BPU 12 Congress

8 Jul 2025, 08:40 → 12 Jul 2025, 13:00 Europe/Bucharest

Politechnica Univ

Tuesday 8 July

09:00 Arrival of the BPU Participants

SEENET-MTP Assessment Meeting and Workshop

July 7-8, 2025, UPB

12:00 Arrival of the BPU Participants

Opening Ceremony

Welcome addresses

Plenary Session 1

1 BPU at its 40th anniversary. A piece of history.

Speaker: Andrei Dorobantu

2 Physics and Spaceflight: A Personal Journey Across Frontiers

Speaker: Dumitru Prunariu

3 Memories of beginnings

Speaker: Ionut Ursu

4 TBA

Speaker: Atish Dabholkar

5 Landscape, swampland and extra dimensions

I will discuss the possibility that the smallness of some physical parameters signals a universe at a large distance corner in the string landscape of vacua. Such parameters can be the scales of dark energy and supersymmetry breaking, which should then be tied to a large `dark' dimension at the micron scale, as dictated by the large distance swampland conjecture.

Speaker: Ignatios Antoniadis

Discussions

Welcome Dinner

Wednesday 9 July

Plenary Session 2

6 Gravitational Waves; the theorists' Swiss knife

I will briefly present how gravitational waves are used to test astrophysical and cosmological models addressing a number of currently open questions about the early stages of our universe. Gravitational waves can test the validity of models of gravity and constrain particle physics models beyond the Standard Model.

Speaker: Mairi Sakellariadou (Physics Department, Strand, London)

7 Terahertz radiation produced by ultraintense laser-solid interactions

Speaker: Luc Bergé (CEA, DAM, DIF)

Round Table “Physics for development – New ways for scientific Cooperation in Europe”

Coffee Break

EPS-TIG hands-on session “Frontier of Quantum Technologies”

Biophysics, Life Sciences, Medical Physics

8 In vitro radiobiological effects of low energy accelerated protons

The unique physical characteristics of hadron therapy—most notably the Bragg peak phenomenon—facilitate highly precise dose deposition that effectively targets tumors while minimizing radiation exposure to adjacent healthy tissues. The advancement of hadron therapy requires thorough research in radiobiology to better understand the complex effects that high doses of charged particles exert on cellular processes. Current studies suggest that the biological effectiveness of hadron therapy exhibits significant variability based on the type of particle utilized and the specific microenvironment of the tumor. Furthermore, the integration of FLASH irradiation regimens, which apply ultra-high dose rates (≥40 Gy/s), with hadron therapy is anticipated to markedly reduce patient exposure while enhancing therapeutic efficacy. This approach aims to minimize damage to normal tissues while maintaining effective tumor control. Understanding key mechanisms such as DNA damage responses, alterations in gene expression, and the effects of tumor oxygenation is crucial for refining treatment protocols in hadron therapy. In this framework, the ion accelerators at IFIN-HH, including two tandem accelerators (9 MV and 3 MV) and one cyclotron (19 MeV for protons), have been adapted to deliver doses ranging from 0 to 10 Gy to biological samples, encompassing both 2D and 3D cell cultures. Notably, a setup for ultra-high dose rate irradiation with protons has been implemented at the 3 MV tandem accelerator, enabling innovative experimental protocols. The results regarding the responses of tumor and normal tissues to accelerated proton irradiation are elucidated and discussed in the context of the prevailing literature, highlighting the potential of proton therapy to improve therapeutic outcomes through tailored approaches.

Speaker: Mihai Radu (1Horia Hulubei National Institute for Physics and Nuclear Engineering, Reactorului 30, Măgurele, Romania)

9 Exploring biophysical and pharmacological properties of Nav1.5 channels with experimental and simulation methods

We performed voltage-clamp experiments on outside-out patches excised from HEK293 cells stably expressing hNav1.5. Upon 3-min exposure to a 808.5 nm laser the peak Na+ current amplitude remained steady (96.64±5.25% of initial values) while in control conditions it decreased (37.95±9.14%); in whole-cell experiments relative amplitudes were 111.2±47.0% (laser) vs. 70.6±33.0% (control). We also titrated the effects of cenobamate on hNav1.5 peak and late current (with ATX-II 100 nM in bath) and found apparent IC50 of 87.6 µM (peak) and 46.5 µM (late). Using a multi-pulse voltage-clamp protocol to assess use-dependent block and recurrence formulae for peak current amplitudes at consecutive pulses obtained with supplementary simplifying assumptions, we estimated state-specific blocking/unblocking rates: for open-state kob=0.00215µM-1ms-1, kob-1=0.189ms-1, for inactivated-state kib=0.0006698µM-1ms-1, kib-1=0.18252ms-1. Applying these and other in vitro pharmacology data (IC50 for hCav1.2, hKv7.1, hERG) to a modified O’Hara-Rudy2011 human ventricular cardiomyocyte electrophysiology model in a 1D string of 50 cardiomyocytes with different connectivities, we found out that at 20-fold reduced intermyocyte gap-junction conductivity (300pS/pF) cenobamate produced significant conduction velocity decreases (0.0148m/s at 0.5 x Cmax vs. 0.0259m/s-control). We obtained an open-conformation 3D model of hNav1.5 using AlphaFold2, we embedded it in a DPPC bilayer model with CHARMM-GUI, corrected residue protonation state (pH7.2) with H++, added 2 Na+ ions in the selectivity filter. By molecular docking we found the cenobamate binding site in the central cavity. We identified 10 mutant variants in the binding site region and explored them via docking and MD followed by MM-PBSA: mutants N1463K/Y and M1766R feature higher predicted inhibitory affinity than wild-type channels.
Acknowledgements: This study was funded by the Romanian Government via UEFISCDI from grant PCE nr. 39/2022: PN-III-P4-PCE-2021-1422 directed by Beatrice Radu.
Competing interests: The authors declare they have no competing interests related to this study.

Speaker: Bogdan Amuzescu (Dept. Biophysics & Physiology, Faculty of Biology, University of Bucharest, Romania)

10 Development of an ultra-high dose rate proton irradiation system for radiobiology studies at a 3 MV TandetronTM

Small accelerators are capable of delivering ultra-high dose rates (UHDR) during proton irradiation, which makes them valuable tools in the development of FLASH radiotherapy. However, achieving accurate in-air irradiation at such dose rates demands exceptionally precise beam characterization. This work describes the way we addressed the challenge of accurate dosimetry while developing a new beamline at the 3 MV Tandetron™ from IFIN-HH, specifically in the context of radiobiology studies. We outline the beamline’s design, construction, and calibration, emphasizing its critical components. Computational work, in the form of FLUKA simulations, blends seamlessly with experiments carried out during the commissioning process. Predicted high spatial precision in dose deposition has been validated through radiochromic film analysis. Accurate dose delivery over time is ensured by stringent regulation of both irradiation duration and dose rate, which we have measured comparatively using a Faraday cup and an Advanced Markus ionization chamber. Finally, we introduce a custom-designed sample holding and manipulation device that significantly improves irradiation efficiency and enhances experimental throughput.

Speaker: Mr Andrei-Theodor Hotnog (Horia Hulubei National Institute for Physics and Nuclear Engineering)

11 BBB-on-a-chip model: new protocols and 3D observations in glass microchips

The blood-brain barrier (BBB) structure is essential for maintaining brain homeostasis by regulating the fluid and substances transport between the bloodstream and central nervous system, while protecting against toxins and pathogens. Disruption of BBB integrity is associated with neurodegenerative diseases like Alzheimer’s and Parkinson’s, in which factors such as inflammation and amyloid-β accumulation impair the barrier function. Accurate in vitro models of the BBB, in particular platforms capable capable of mimicking 3D environment, are essential for studying pathological mechanisms. The evaluation of BBB integrity involves the observation of tight junction proteins like zonula occludens-1 (ZO-1) through immunofluorescence microscopy.
In this study, we investigated the impact of three different fixation protocols, on the immunofluorescent detection of ZO-1 in the b.End3 mouse brain endothelial cell line. We also evaluated how the composition of the culture medium influences ZO-1 expression and visualization. Our results showed that Advanced DMEM cell culture medium provided a more stable environment for ZO-1 expression in comparison with standard DMEM, while methanol and acetone fixation significantly improved the signal intensity and image clarity, regardless of the culture medium used.
We further validated the protocols in a 3D microfluidic glass chip fabricated in photosensitive glass by picosecond laser assisted etching. The microchip allowed the clear visualization of tight junction architecture within a confined 3D microscale environment. Our results may contribute to either standardization of immunofluorescence workflows in 3D spaces or support the use of glass microfluidic platforms for rigorous biophysical studies of BBB integrity

Speaker: Cristina Elena Staicu (Center for Advanced Laser Technologies, National Institute for Laser, Plasma and Radiation Physics, Măgurele, Romania Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania)

Condensed Matter, Materials and Applied Physics

12 Seebeck effect in the charge density wave state of organic conductor α-(BEDT–TTF)2KHg(SCN)4

Detailed studies of the interlayer Seebeck effect of organic conductor α-(BEDT-TTF)2KHg(SCN)4 as a function of temperature, magnetic field strength, and field orientation are reported. We find that the formation of the CDW0 state is mainly due to the Fermi surface reconstruction as a result of the magnetic breakdown effect since the onset magnetic field for this state is near the magnetic breakdown field. However, the electron-phonon coupling might be also an important mechanism in formation of the CDW0 state in α-(BEDT-TTF)2KHg(SCN)4 as evident from the temperature dependence of the interlayer Seebeck effect. We find that a third CDW state develops at low temperatures below 3K, angles above θ = 40° and fields above the kink field B=22 K. At these angles and fields the high field CDWx state with a field dependent wavevector is replaced by the CDWy state with an angle dependent wavevector. In addition, we find that the third CDW state resembles some of the properties of the CDW0 state but the Fermi surface is less imperfectly nested than in the CDW0 state. The temperature measurements reveal substantial differences in the T−dependent profiles of the Seebeck effect depending on the magnetic field orientation. This allows to specify the temperature interval of existence of each of the CDW states for a given magnetic field strength and orientation as well as to reveal the presence of other possible states and transitions in this organic conductor that have not been previously detected by magnetoresistance and/or magnetization measurements.

Speaker: Danica Krstovska (Ss. Cyril and Methodius University, Faculty of Natural Sciences and Mathematics, 1000 Skopje, Macedonia)

Bucharest presentation_Krstovska.pptx

13 Carbon-Silicon- Titanium - Aluminum nanostructures doped with nitrogen: synthesis and characterization

Using Thermionic Vacuum Arc technology were created nanostructured thin films using four material: graphite, titanium, silicon, and aluminum, with the inclusion of nitrogen, on the Si substrate. TDS analysis reveal the presence of nitrogen in all cases. The Raman spectra show that the nitrogen treatment of the films leads to the formation of nitrides for each compound. The infrared absorption spectra are dominated by the formation of C-N bonds exactly as in Raman spectra. EDX and Elemental composition show that the values of atomic percentage depending of the substrate deposition temperature. EDX and STEM mapping was carried out to evaluate sample composition. Based on XPS depth profile it turns out that . the peaks of the three materials Si, Al and Ti are well defined whereas O concentration is much lower, due to the high working temperature. Based on nanoidentation studies, Young modulus and Hardness are measured.The values of the Hardness in the case of N-doped thin films are generally bigger compared with the values in the case of undoped films. The tribology data reveal that the values of the friction coefficient in the case of N-doped thin films are generally smaller compared with the values in the case of undoped films. Electrical conductivity on the Ti-Si-Al-C-N films shows the increase of conductivity with the increase of the nitrogen content.

Speaker: Victor Ciupina (Ovidius University)

14 Nanoscale thermal management with newly proposed 2D MOSFETs

In nano-electronic technology, the overall thermal reliability is recognized by the temperature of the hottest zone on the die. Accordingly, the transistor with a lower maximum temperature is easier kept under the working threshold temperature. Thus, the material selection and also the heat spreader design, as the thermal management solutions for controlling the temperature of the hotspots, are always the issues of concern. While the attempts to find the proper methods for heat removal are being performed, looking for low-dimensional silicon replacement nominees, with the lowest peak temperature, is also developing as the easier and more feasible choice for the transistor industry. The present research investigates the thermal reliability of the 2D MOSFETs, tracking the achieved peak temperature under the influence of self-heating. The framework is the non-equilibrium Monte-Carlo simulation of the phonon Boltzmann equation. This formalism is used to comparative study of the well-known 2D replacements for silicon channels such as graphene, blue phosphorene, germanene, silicene, MoS$_2$, the 2D complex MA$_2$Z$_4$ structures of MoSi2N4 and WSi2N4, and the recently famous 2D silicon carbide. Our calculations establish that ambient stable WSi$_2$N$_4$ presents the lowest peak temperature rise in comparison to the other studied 2D channels with the peak temperature rise of 400 K in response to the heat source of Q=1×10 W/m$^3$. The 2D SiC with a very high melting point of 4050 K, stands in second place with the maximum temperature of 480 K, while MoSi2N4 and blue phosphorene occupy the next places. Consequently, we have obtained that WSi$_2$N$_4$, 2D SiC, MoSi$_2$N$_4$ and blue phosphorene are suitable for thermally efficient transistors. In other words, the limit of the energy and economic cost of producing the verified materials chips meets the value of the product for the enterprises.

References
[1] A. Bahadori and Z. Shomali, Thermal transport in thermoelectric materials of SnSSe and SnS2: A non-equilibrium Monte-Carlo simulation of Boltzmann transport equation, Case Studies in Thermal Engineering, 57, 104377, (2024).

[2] Z. Shomali, An investigation into the reliability of newly proposed MoSi2N4/WSi2N4 field- effect transistors: A Monte Carlo study, Micro and Nanostructures, 182, 207648, (2023).

[3] Z. Shomali, R. Asgari, Effects of low-dimensional material channels on energy consumption of nano-devices, International Communications in Heat and Mass Transfer, 94, 77 (2018).

[4] Z. Shomali, B. Pedar, J. Ghazanfarian, A. Abbassi, Monte-Carlo Parallel Simulation of Phonon Transport for 3D Nano-Devices, International Journal of Thermal Sciences, 114, 139 (2017).

Speaker: Zahra Shomali (Tarbiat Modares University)

15 Molecular modelling of charge transfers in hybrid organic-inorganic photovoltaic devices

We report results of computational studies investigating the electron transfer between the dye and the TiO2 nanocluster as well as between the electrolyte and the dye, to understand the mechanisms that influence the performance of dye-sensitized solar cells. By means of density functional theory calculations, we determine the parameters of Marcus’ theory for charge transfer from a cobalt-based electrolyte to a sensitizing dye with a triphenylamine donor group. We also study TiO2 nanoclusters of various sizes as well as of complex systems with various molecules adsorbed onto these clusters, with the goal to understand charge transfer processes relevant not only for hybrid organic–inorganic photovoltaics but also for the photocatalytic degradation of pollutants. We find acceptable minimal sizes of the (TiO2)n (n = 14, 24, 34, 44, 54) nanoclusters, to model systems and interface processes that occur in hybrid photovoltaics. We illustrate various adsorption cases with a small rigid molecule based on coumarin, a larger rigid oligomethine cyanine dye with indol groups. We argue that cluster sizes with n ≥ 34 are necessary to provide the reliability expected from the calculations but recognize that the use of much larger clusters may bring little improvement at a significantly higher computational cost.

Speaker: Mihai GIRTU (Ovidius University of Constanta)

16 Nonreciprocal transport in Josephson junctions made of d-wave superconductors through ferromagnetic layer in the presence of interfacial Rashba spin-orbit coupling

We have studied theoretically the effect of interfacial Rashba spin-orbit coupling (SOC) on the Josephson effect between two $d$-wave superconductors with ferromagnetic layer in between, based on the Bogoliubov-de Gennes approach, extended McMillan’s Green function formalism, and generalized Furusaki-Tsukada treatment. If both time-reversal and space-inversion symmetries are broken, Josephson junction can exhibit Josephson diode effect (JDE) characterized by nonreciprocal behavior in the critical supercurrent in two opposite directions, as well as finite current at zero phase difference known as anomalous Josephson effect (AJE). We found that the appearance of the JDE and AJE are conditioned by the simultaneous presence of interfacial Rashba SOC, nonzero component of magnetization out of junction plane, and asymmetric orientation of two $d$-wave superconductors. This is in accordance with symmetry analysis of global Hamiltonian of junction. We found that high diode efficiency in this kind of junctions can be realized by tuning the orientations and magnitudes of relevant ingredients. The cumulative ground state of junction is not pure $0$ or $\pi$ because the different transverse channels have different phase differences. We predict that phase transition between $0$-like and $\pi$-like states can be achieved by modulating the strength of the interfacial Rashba SOC. Temperature dependence of JDE is shown and the possibility of a temperature $0$-$\pi$-like crossover is predicted.

Speaker: Stevan Djurdjević (University of Montenegro, Faculty of Science and Mathematics)

High Energy, Particle Physics, Gravitation and Cosmology

17 Evolution and Status of Particle Accelerators Based Studies in Türkiye

This study provides an overview of the evolution and status of particle accelerators and their applications in Türkiye. It presents a comprehensive review of national projects, graduate institutes, research infrastructures, international collaborations, and scientific events. The progress of the Turkish Accelerator Center (TAC) and the establishment and research potential of the TARLA facility are discussed. In addition, the role of particle accelerators in medical and industrial applications is also highlighted, alongside a chronological overview of national scientific activities in this field. Türkiye’s associate membership in CERN and its contributions to CERN experiments, as well as its involvement in SESAME and related R&D efforts, are discussed. Finally, future perspectives on the development of particle accelerators, detectors, and their applications in Türkiye are outlined.

Speaker: Prof. Ömer Yavas (Ankara University (TR))

18 Path integral for non-canonical Lagrangians and its applications

We consider a class of Lagrangians in which the kinetic term has a noncanonical form. Among models based on this class of Lagrangians, usually referred to as k-essence, and in the context of cosmology and inflation theory to k-inflation models, we consider in more details a family of Dirac-Born-Infeld (DBI) Lagrangians.

In the last several decades they find a significant room of application in cosmology and inflation theory. Dynamics governed by DBI Lagrangians are closely related to dynamics of the tachyon fields. We present the new results on path integral formulation of the Inverted Caldirola-Kanai oscillator, using method of the locally equivalent quadratic actions.

Our presentation is completed by a short discussion of DBI Lagrangians dynamics on nonarchimedean spaces, their p-adic and adelic aspects and application in cosmology.

Speaker: Goran S. Djordjevic (Department of Physics, University of Nis, Serbia)

19 Jordan algebras and conformal models

Jordan algebras were invented in a search of an axiomatic system for quantum mechanics.

They turn out to be extremely effective in describing conformal symmetries via the Tits-Kantor-Koecher construction assigning a light cone to each Euclidean Jordan algebra.

Using the Gunaydin oscillator realization we construct quantum mechanics systems with hidden

conformal symmetry in various dimensions such as Hydrogen atom, Dyon-Dyon system, Landau problem.

Speaker: Todor Popov (Bulgarian Academy of Sciences / American University of Bulgaria)

20 Braided BV quantization beyond Moyal deformation: scalar fields in λ-Minkowski NC spacetime

In this talk we will review the newly developed method for quantization of noncommutative (NC) field theories, the braided BV quantization. We will discuss results for the NC QFT on the Moyal space and then we will generalize these to a spacetime with non-constant noncommutativity, the lambda-Minkowski spacetime. We will show that, in the case of scalar field theory, the NC contribution enters in a specific way and we will discuss the obtained results in some detail.

Speaker: Marija Dimitrijevic Ciric (University of Belgrade Faculty of Physics)

Lunch Break

Poster Session 1

21 Synthesis and characterization of NaMgF3:La2O3 NPs

Recently, interest in lanthanum as a dopant in host materials has increased due to its ability to significantly modify the optical and structural properties of its host material. Fluoride nanocrystals doped with rare earth ions are of great interest due to their potential applications in lighting and displays, boost converters, biological fluorescent labels, transparent glass, scintillators, optical amplifiers, solar cell amplification and photodynamic therapy. The NaMgF3 material have been considered an ideal host for getting up- and down-conversion emission. The luminescence properties of Ln-doped NaMgF3 have revealed that the fluoroperovskite host is an excellent compound through which spectral information on various divalent lanthanides may be obtained. In this study NaMgF₃ doped with La₂O₃ rare earth oxide in a mass ratio of 1:0.2 was synthesized through co-precipitation and solid-state reaction (700°C, 6h). The X-ray diffraction pattern was recorded to check the phase purity of the synthesized compound. In order to identify the functional groups, the Fourier Transform Infrared spectral analysis have been performed. Chemical composition of the synthesized compounds was checked by the energy - dispersive X-ray spectra. XRD analysis of undoped NaMgF₃ exhibits crystalline structure with grown crystallite size of 35.7 nm and a strain of 0.27%. Doping NaMgF₃ with La₂O₃ reduces the crystallite size to 34.5 nm, while lattice strain remains unchanged at 0.27%. The decrease in crystal size is influenced by the radius of its constituent ions. La³⁺ doping has no effect on strain, suggesting that La³⁺ ions (103.2 pm) are incorporated without significantly altering the lattice parameters, possibly due to their closer match with Na⁺ ionic radius (102 pm). Analysis of the survey XPS spectra of NaMgF₃ and NaMgF₃:La₂O₃ in the whole binding energy region are discussed. XPS analysis of the O1s core level for NaMgF₃ and NaMgF₃ doped with La₂O₃ reveals distinct oxygen for undoped NaMgF₃, at 539.1 eV, 532.1 eV, 529.3 eV, and 529.5 eV, likely corresponding to surface hydroxyl groups or adsorbed water (539.1 eV), lattice oxygen in NaMgF₃ (532.1 eV), and oxygen in metal-fluoride or oxide-related bonds (529.3–529.5 eV). NaMgF₃:La₂O₃ shows peaks at 539.4 eV, 532.4 eV, and 529.9 eV, with slight shifts suggesting minimal lattice disruption by La³⁺ ions, possibly due to their similar ionic radius of Na⁺. The shifts and peak position variations of all elements of the compound influenced the electronic structure and potentially enhancing physical properties. XPS analysis of the F1s core level for NaMgF₃:La₂O₃ reveals F1s peaks at 687.5 eV and 686.3 eV, with a slight shift to higher binding energy for the main peak and an slightly increase for the secondary peak, suggests minimal lattice perturbation by La³⁺ ions, consistent with its unchanged lattice strain (0.27%) and near-identical crystallite size (34.5 nm). Knowledge of the speciation of La3+ in the lattice of NaMgF₃ is essential to understand how they incorporate, since the local structure of the dopant and its homogeneity within the host, determine its optical properties.
Keywords: NaMgF3 and NaMgF₃:La₂O₃ NPs, X-ray Analysis, Composition.
Acknowledgements:
This paper was financially supported by the National Agency for Research and Development of the Republic of Moldova, project “Nanoparticles Doped with Rare Earth Elements for Applications in Biomedical Imaging and Cancer Cell Therapy”, #20.80012.5007.22SE.

Speaker: Tamara Potlog (Laboratory of Organic/Inorganic Material for Optoelectronics, Moldova State University, A. Mateevici 60 str., 2009, Chisinau, Moldova)

22 "molecularDNA" example application for the simulation of radiation-induced DNA damage using Geant4-DNA

A significant effort is underway in the global scientific community to develop accurate models of DNA damage in cells induced by hadronic particles, in the context of hadrontherapy cancer treatment or for future manned space exploration missions. Several Monte Carlo Track Structure software codes (MCTS) have been developed for simulating early-DNA scale events to macroscopic radiobiological endpoints. These include cell survival, single and double DNA breaks, DNA repair, and other late effects. The Geant4-DNA extension (https://geant4-dna.org/) of the Geant4 (GEometry ANd Tracking) toolkit is the first open-source and general-purpose MCTS code, delivering a framework for simulating the physical interaction of radiation with DNA molecules and the chemical stages of water radiolysis, including the production of oxidative radical species. It also provides a variety of geometrical models of cell nuclei with a complete DNA genome implemented. The geometries of cell nuclei are, by default, seeded from a fractal packing, where the DNA chain is a continuous Hilbert curve made of straight and turned chromatin sections, including nucleosomes. A new model of cell nuclei, named “complexDNA," has been recently created, incorporating all 23 chromosome pairs of a human cell. It shows minimal discrepancies in DNA damage yield compared to the default model and achieves around three times improved CPU time. The geometric models are interfaced with the direct and indirect stages of DNA damage induction, and the advanced example of Geant4-DNA named "molecularDNA" was released in December 2022 (https://moleculardna.org). An overview of the “molecularDNA” application will be provided, covering its design, purpose, and key features, and will include a demonstration of its predictive performance compared to experimental data from helium ion beam irradiation of cancer cells. DNA rejoining and cell survival prediction in V79 cells using Geant4-DNA will also be presented. The new computational approach for generating complex chromosomal DNA geometries will be described along with a discussion of other methods to enhance the modelling of cell geometries.

1. K. P. Chatzipapas, N. H. Tran, M. Dordevic, S. Zivkovic, S. Zein, W.-G. Shin, D. Sakata, N. Lampe, J. M. C. Brown, A. Ristic-Fira, I. Petrovic, I. Kyriakou, D. Emfietzoglou, S. Guatelli, S. Incerti, Simulation of DNA damage using Geant4-DNA: an overview of the “molecularDNA” example application, Prec. Radiat. Oncol. 7 (2023) 4-14.
2. K. Chatzipapas, M. Dordevic, S. Zivkovic, N. H. Tran, N. Lampe, D. Sakata, I. Petrovic, A. Ristic-Fira, W.-G. Shin, S. Zein, J. M. C. Brown, I. Kyriakou, D. Emfietzoglou, S. Guatelli, S. Incerti, Geant4-DNA simulation of human cancer cells irradiation with helium ion beams, Phys. Med. 112 (2023) 102613.
3. K. Chatzipapas, H. N. Tran, M. Dordevic, D. Sakata, S. Incerti, D. Visvikis, J. Bert, Development of a novel computational technique to create DNA and cell geometrical models for Geant4-DNA, Phys. Med. 127 (2024) 104389.
4. D. Sakata, R. Hirayama, W.-G. Shin, M. Belli, M. A. Tabocchini, R. D. Stewart, O. Belov, M. A. Bernal, M.-C. Bordage, J. M.C. Brown, M. Dordevic, D. Emfietzoglou, Z. Francis, S. Guatelli, T. Inaniwa, V. Ivanchenko, M. Karamitros, I. Kyriakou, N. Lampe, Z. Li, S. Meylan, C. Michelet, P. Nieminen, Y. Perrot, I. Petrovic, J. Ramos-Mendez, A. Ristic-Fira, G. Santin, J. Schuemann, H. N. Tran, C. Villagrasa, S. Incerti (2023), Prediction of DNA rejoining kinetics and cell survival after proton irradiation for V79 cells using Geant4-DNA, Phys. Med. 105 (2023) 102508.
5. A. Ristić Fira, O. Keta, V. Petković, M. Đorđević, G. Petringa, S. Fattori, R. Catalano, G. P. Cirrone, G. Cuttone, D. Sakata, H. N. Tran, K. Chatzipapas, S. Incerti, I. Petrović, In vitro validation of helium ion irradiations as a function of linear energy transfer in radioresistant human malignant cells, IJRB 100 (2024) 10:1456-1437.

Speaker: Milos Dordevic (Vinca Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Mike Petrovica Alasa 12-14, 11351 Vinca, Belgrade, Serbia)

23 A New Method and Device Concept for Real-Time, In-Situ Evaluation of Microplastics in Water

Traditional methods for evaluating microplastics in water environments are hindered by
complexity, accuracy issues, and inefficiency in processing large volumes of water
within realistic timeframes and costs. This patented approach introduces a novel
measurement technique—multispectral transmission evaluation using specifically
prepared pulsed, coherent emission in the visible spectrum. This emission interacts with
water and single plastic particles (LDPE, HDPE, and PP) of various sizes and forms as
they pass through the active sensor volume. This work presents the theoretical
foundation of the method, and the initial results obtained from laboratory experiments
conducted in 2024.

Acknowledgements
This document was created with the financial support of the European Union – Next Generation EU, National Recovery and Resilience Plan, BG-RRP-2.012 Funding for PhD studies in the field of green and digital technologies, Contract No. BG-RRP-2.012-0003-C01, "Investigation of the influence of the shape, composition and structure of microplastics (50 micrometers - 5 mm) from PE, PP and PET on the absorption of the visible and near UV spectrum in an aquatic environment". The sole responsibility for the content of the document lies with the Institute of Solid State Physics and under no circumstances can it be assumed that this document reflects the official position of the European Union and the Monitoring and Reporting Structure of the Bulgarian Academy of Sciences.

Speaker: Georgi Vladimirov (Institute of Solid State Physics, BAS)

Title_abstract_bucharest_poster.docx (1).pdf

24 Analysis of equilibrium states in a Pople-Karasz model using mean and Gaussian curvatures

In earlier works on Pople-Karasz model [1, 2], equilibrium states are displayed by contour mapping, where one coordinate is associated with the orientational order parameter $S$ and the other with the positional order parameter $Q$. In this work, we introduce their geometric analysis by determining mean and Gaussian curvatures ($H$, $K$). From the temperature variation of $H$ and $K$ in the disordered state ($S = Q = 1/2$), we have reported the local shapes of equilibrium free energies for the stable and unstable solutions. It is important to mention that a minimal surface for the disordered case with $H = 0$, $K < 0$ is explicitly observed. For the ordered case ($S > 1/2$,$Q > 1/2$), it is found that the curvature $H$ displays a cusp singularity and a convergence of $K$ is observed at the criticality. These results are compared with the similar works [3] and a very good agreement is found.

[1] M. Keskin, Ş. Özgan, A Model for Studying How to Obtain the Metastable States, Physica Scripta 42 (1990) 349-354.
[2] Ş. Özgan, Investigation of stable, metastable and unstable solutions on molecular crystals, Mod. Phys. Lett. B 21 (2007) 817-830.
[3] R. Erdem, Mean and Gaussian curvatures of equilibrium states for a spin-1 Ising system: existence of minimal surface in the paramagnetic solutions, Eur. Phys. J. Plus 138 (2023) 306.

Speaker: Rıza Erdem (Akdeniz University)

25 Application of Digital Industrial Radiographic Testing in the Inspection of Welds Based on European Standards

Industrial Radiographic Testing (RT) is a fundamental method within Non-Destructive Testing (NDT), widely applied for quality assurance and the evaluation of material integrity in metallic structures. This technique is essential for detecting internal welding defects, identifying volumetric discontinuities, and assessing both the external and internal geometries of components. RT primarily relies on X-ray and gamma-ray sources, which possess the ability to penetrate solid materials and reveal hidden flaws. With advancements in imaging technologies, digital radiography has emerged as a superior alternative to traditional film-based methods, offering higher resolution, reduced radiation exposure, and faster image processing. This study presents the core principles and practical applications of digital industrial radiographic testing, with a focus on its implementation for weld inspection in accordance with European standards such as EN ISO 17636-2 and EN ISO 10675. Four metallic blocks were examined using an X-ray tube and advanced digital radiographic systems, including imaging plates and flat-panel detectors. The testing strictly adhered to relevant protocols and procedures defined by international and European standards, including ISO EN 9712, as upheld by the International Committee for Non-Destructive Testing (ICNDT). Key image quality parameters, such as image quality indicators (IQIs) and contrast-to-noise ratio (CNR), were evaluated to ensure the accurate detection and characterization of defects. The results confirm that digital radiographic techniques are highly effective in identifying and characterizing common weld defects such as porosity, lack of fusion, cracks, and slag inclusions. The study underscores the importance of adopting standard-compliant digital radiographic methods to ensure reliable and efficient inspection of welded joints. This approach enhances safety, traceability, and performance in industrial components by minimizing the risk of undetected flaws.

Speaker: Mirela Alushllari (Institute of Applied Nuclear Physics)

alushllarim_abstract_Application of Digital Industrial Radiographic Testing in the Inspection of Welds Based on European Standards.docx

alushllarim_RT-Poster BPU 12 - format 1 pg.ppt

26 Assessment of Indoor Radon Concentrations in Tirana’s Schools and Workplaces Using Passive Techniques

Radon monitoring in Albania has been focused on schools and workplaces, where radon is classified as an existing exposure risk. This study was conducted in Tirana, home to approximately one-third of Albania’s population. The geological profile of Tirana comprising recent volcanic rocks, granitic formations, and permeable soils near seismic zones contributes to increased indoor radon potential and, consequently, in elevated health risks due to higher exposure levels.
The survey included 80 schools and 70 workplaces, with measurements taken on first floors and basements. Passive radon detectors (CR-39) were deployed for three-month periods in two different periods, winter and spring. These measurements were conducted by using passive monitoring methods. In schools, detectors were primarily installed in classrooms, libraries, and gymnasiums; meanwhile in workplaces, they were placed in offices, meeting rooms, and laboratories.
In many cases, indoor radon concentrations exceeded the recommended reference level of 300 Bq/m³. Detected radon levels ranged from 24 to 1000 Bq/m³ in schools and from 22 to 400 Bq/m³ in workplaces. A descriptive analysis revealed a positively skewed and peaked distribution, indicating that the data follow a log-normal distribution. Based on these results was performed the Natural Radiation Background Assessment and Determination in Tirana district and the average dose rate level was 0.063 µSv/h. The findings highlight the need for immediate mitigation measures, such as improving ventilation systems and conducting regular monitoring. Continuous radon surveillance is recommended to maintain safe levels and minimize health risks. Additionally, increasing public awareness especially among vulnerable groups is essential to address the health hazards of radiation exposure to radon.

Speaker: Prof. Kozeta Tushe (University of Tirana)

Albania National Radioactive Waste Storage Facility Contamination Monitoring.-Poster Presentation.pdf

BPU 2025_K.Tushe.pdf

Evaluation of the activity of a ¹³⁷Cs radioactive source utilized in oil-welling in Albania-Poster Presentation.pdf

27 Assessment of X-ray field congruence and beam perpendicularity testing for diagnostic equipment by medical physicists and radiographers in various hospitals in Albania

Institute of Applied Nuclear Physics (IANP) is the first government authority performing QC tests for radiological equipment used in every radiology department in Albania involving adherence to international guidelines and approval by our regulatory authorities. This study aimed at investigating the challenges facing the implementation of the QC program by radiographers and medical physicists in diagnostic radiography and fluoroscopy units used in our country including x-ray projection tests. QC tests results are presented for 23 radiographic and 10 fluoroscopy systems assessing the X ray–light beam alignment and X-ray beam perpendicularity tests using a collimator test tool, a beam alignment - cylinder test tool, a Leeds Test Objects′ FLUORO-4 phantom and coins method. Both tests are performed at a source-to-image distance (SID) of 100 cm. Analysis of the results showed that only 86 % of the radiographic devices evaluated in this study were within acceptable criteria for the light and X-ray field misalignment test being lower than 2% of the SID. For the perpendicularity of X-ray beam test 95.5% of the radiographic devices evaluated were within acceptable criteria showing an angle between the central axis of the X-ray beam and the plane of the image receptor lower than 1.5 degree. All fluoroscopy systems were found to be within acceptable criteria for both tests. It was found that many of the radiological devices included in this study were not under a regular QC program by radiographers due to lack of training and available test tools. It was emphasized to all the radiographers that conducting a regular QC test should be part of their routine work so they can detect at an earlier time any possible defect in the operation of the radiological equipment in use. For the X-ray beam alignment tests they were recommended to use the coins method. It was also suggested to the hospital’s management teams that all radiological devices in use should have performance supervision at a proper periodical time and not take place only during inspection or licensing process.

Speaker: Dr Luljeta Disha (Institute of Applied Nuclear Physics,Unversity of Tirana)

Poster 03.07.2025 BPU 12 CONGRESS ID.Abstract 18.pdf

28 Detection of hydrogen isotopes in fusion-relevant targets via laser ablation and microwave-induced plasma

Abstract. The analysis of plasma facing components (PFCs) of fusion machines using laser-induced breakdown spectroscopy (LIBS) technique is widely distributed in the fusion community. Difficulties arise when the spectroscopic measurements of tritium retention are performed, particularly the resolving of deuterium (Dα) and tritium (Tα) Balmer alpha lines becomes a major issue.
This study explores using microwave-induced plasma (MIP) generated in a custom-designed low-pressure chamber as a potential solution to this problem. The target material is introduced into the MIP via laser ablation using Nd:YAG laser, and the spectral signal is monitored with a high-resolution spectrometer and an ICCD camera. Two silicon-based targets were utilized: the first, coated with carbon (C) and methane (CH4), was used for optimization of the measurement system, whereas the second, coated with C and D, was used for final measurements.
As part of the optimization process, the optimal time window for signal recording was determined relative to the laser Q-switch trigger. Additionally, crater profiles were analyzed using an optical profilometer, yielding the estimated ablation rate of approximately 400 nm per laser pulse at a fluence of 5.4 J/cm^2.
The final measurements indicate that, with the current setup, the lowest detectable tritium level would correspond to a Tα line intensity between 30% and 50% of the Dα line intensity (Fig. 1). These results show that this MIP-based setup is a promising tool for such analyses, providing reliable and fast determination of tritium content retained in fusion-relevant materials.

Speakers: Nikola Vujadinović (Institute of Physics, Belgrade), Dr Ivan Traparić (Institute of Physics, Belgrade)

Abstract for BPU conference 2025.docx

29 Dosimetric Verification of Monte Carlo and Collapsed Cone Models

Monte Carlo and Collapsed Cone algorithms are widely used for dosimetric verification and calibration of linear accelerators in external beam radiotherapy. This study presents a comparative dosimetric verification of both models at different depths and field sizes using an Elekta linear accelerator. The goal is to assess the agreement between theoretical dose distributions and measured data, a crucial aspect in ensuring treatment accuracy in clinical radiotherapy. Measurements were conducted using a photon beam, a Farmer-type ionization chamber, and a water phantom. The experimental results were compared to dose calculations obtained from the Monte Carlo and Collapsed Cone algorithms. These models provide a predictive framework for estimating radiation dose distribution in tissues at varying depths. Verifying their accuracy is essential for confirming the consistency between theoretical planning and physical dose delivery. Our results show a generally acceptable level of agreement between the measured and calculated doses, supporting the validity of both algorithms for clinical use. Differences observed in specific field sizes and depths offer insight into model limitations and potential areas for optimization. This verification contributes to improved confidence in treatment planning systems and enhances the quality assurance process in modern radiotherapy.

Speaker: Mr Eno Bakiri (Aleksandër Xhuvani University Elbasan, Albania)

Dosimetric Verification of Monte Carlo and Collapsed Cone Models.docx

30 Electrical properties and structure of nanocomposite electrolytes of ion-conducting polymer (PEO) doped with nematic liquid crystals (5CB) and single wall carbon nanotubes

We conducted an in-depth investigation of the electrical and structural properties of flexible films (approximately 50 μm in thickness) composed of nematic nanocomposites, which were synthesized from the nematic liquid crystal pentylcyanobiphenyl (5CB), polyethylene oxide (PEO) polymer complexed with sodium metaperiodate (NaIO₄) as an ion donor, and single-walled carbon nanotubes (SWCNTs) incorporated as a conductive filler. The films' composi-tion was as follows: a 70:30 wt.% weight ratio of 5CB:PEO, NaIO₄ at 5 wt.%, and varying concentrations of SWCNTs from 0 to 0.25 wt.%. The SWCNTs exhibited an average diameter of 1.5 nm and an average length of 7 μm. The influence of SWCNT addition at different con-centrations on the properties of the PEO-5CB-NaIO₄-SWCNT films was systematically ana-lyzed. The films' microstructure was characterized using polarized optical microscopy, and their Na+ ion conductivity was determined by complex electrical impedance spectroscopy. Notably, the incorporation of SWCNTs led to a significant enhancement in the morphology and ionic conductivity of the PEO-5CB-NaIO₄-SWCNT films. This improvement positions the nanocomposites as promising candidates for dielectric and ion-conductive applications.

Acknowledgements: Work supported by the Ministry of Education and Science of Bulgaria (MESB), through the National Research Fund of Bulgaria (research project „Liquid crystal nanocomposites for applications in photonics, sensors and biomedicine“, No. KP-06-N58/6/2021).

Speaker: Yordan Marinov

31 Evaluation of the activity of a ¹³⁷Cs radioactive source utilized in oil-welling in Albania.

The Institute of Applied Nuclear Physics (IANP) is responsible for the national management of radioactive waste and disused sealed radioactive sources (DSRS) in Albania. It collaborates with public and private entities to ensure the safe transport and storage of radioactive materials.
This study outlines the procedure used to evaluate the total activity of two ¹³⁷Cs sources with unknown activity. In 2018, IANP received five DSRS from the Geophysical Service Center in Fier, following the closure of their temporary storage facility. Based on source certificates and on-site measurements, the inventory included: two ²⁴¹Am-Be sources (5 Ci each), one ¹³⁷Cs source (300 mCi), and two ¹³⁷Cs sources (52 mCi and 51 mCi, dated July 1978) stored together in a single container.
To verify whether both ¹³⁷Cs sources were encapsulated together, activity was estimated using point-source geometry. The measured total activity was 1.418 GBq, closely matching the decay-corrected certificate value of 1.528 GBq (as of March 2018), confirming the presence of both sources in one capsule.
All sources were subsequently transferred to the National Radioactive Waste Storage Facility in Tirana.

Speaker: Prof. Kozeta Tushe (University of Tirana, Institute of Applied Nuclear Physics)

Evaluation of the activity of a ¹³⁷Cs radioactive source utilized in oil-welling in Albania..docx

32 Gamma Spectrometry Evaluation of Soil Radioactivity in the City of Veles and Its Environs

To obtain the baseline levels of soil radioactivity in the city of Veles and its environs, 53 topsoil samples were collected from uniformly distributed sites across an area of $1200\;\mathrm{km^2}$. Following appropriate laboratory preparation, gamma spectrometry was used to determine the activity concentrations of the radionuclides present in the soil samples. The analysis focused on the three most relevant naturally occurring radionuclides $^{40}$K, $^{226}$Ra, and $^{232}$Th, along with the artificial radionuclide $^{137}$Cs. Based on the measurement results, the absorbed dose rate in air and the annual effective dose rate were calculated. After descriptive statistics was made, the mean, median, minimum, and maximum values of the activity concentrations and radiation hazard indices were compared with results from similar studies conducted in Macedonia and across the Balkans, revealing no significant increases or potential health risk to residents. Spatial distribution maps illustrated significant variability in radionuclide concentrations, indicating the influence of geographical location, geology, and lithology as the main contributing factors.

Speaker: Irena Zlatanovska (Institute of physics, Faculty of natural sciences and mathematics - Skopje, Ss. Cyril and Methodius University in Skopje, Macedonia)

33 Hidden colours of Albania: Fresco pigments study from an isolated church in Leshnicë, 18th–19th century

In the 18th and 19th centuries, fresco painting in the Balkans evolved under the influence of political shifts, religious continuity, and cultural exchange. Despite Ottoman rule, Orthodox Christian traditions remained strong, blending with local and folk elements to create a unique artistic language. These frescoes became not only religious symbols but also quiet affirmations of cultural identity and resilience, foreshadowing the region’s modern art movements. Artists primarily used natural pigments like lead white, calcite, and ochre due to their availability and durability, while rare pigments such as azurite and lapis lazuli appeared only occasionally. Although synthetic colors like Prussian blue and chrome yellow spread across Europe in the 19th century, their use in the Balkans remained limited, reflecting regional preferences and the enduring legacy of Byzantine art.
The frescoes in the Monastery of the Presentation of Christ (Ipapandia) in Leshnicë e Sipërme were analyzed in situ using portable µ-XRF across 34 points, revealing that different painters likely worked at different times. The church pigments show distinct elemental profiles tied to their colors, with Fe-rich ochers and Cu-containing greens being most common. Elevated levels of Pb, Hg, and Sb suggest the use of hazardous minerals such as cinnabar, stibnite, or minium, possibly indicating regional practices or environmental contamination. The high antimony content in red and black pigments points to the deliberate use of Sb-rich materials. Overall, the results reveal complex pigment mixtures shaped by local sources and historical techniques.

Speaker: Prof. Olta Çakaj (Department of Physics, Faculty of Natural Sciences, University of Tirana)

Olta Çakaj et al.pdf

34 Implementation of quality control procedure for Computed Tomography imaging modalities in radiology departments in Albania

CT scanning examination is rapidly increased in Albania especially during and after coronavirus pandemic crisis. Having the highest dose procedures encountered in medical imaging, radiation dose in CT scans is of crucial consideration so, by prioritizing quality control (QC) of these x-ray medical devices all healthcare professionals can ensure not only optimal image quality but also protection of patients from radiation risks. QC of radiological medical devices in Albania has started only during the last ten years and is applicated every three years from the Institute of Applied Nuclear Physics (IANP) according to our national radiation protection regulation. Procedure of QC testing for CT scanners in our country includes the measurements of CT numbers and uniformity expressed in Hounsfield unit (HU), Volume Computed Tomography Dose Index (CTDI vol) and irradiated slice thickness. Measurements are carried out using an ACR Gammex 464 phantom containing five inserts of different tissue materials (polyethylene, solid water, air, acrylic, bone) equivalent to human tissue, a pencil ionization chamber together with a standard body and head phantoms with 32 and 16 cm diameter respectively. The aim of this study was to investigate the QC implementation on 13 CT scanners used in different radiology departments in Albania. All the data are taken during the performance of quality control tests for the first time and based on the analysis of the results it was found that CT number accuracy tests were within tolerance for 92% of CT scanners. CT number uniformity for water values and irradiated slice thickness tests were within the tolerances for all the CT scanners. CTDI volume measurements for body phantom ranged from 8.1 mGy to 24.6 mGy while CTDI volume for head phantom ranged from 24.3 mGy to 66.1 mGy. Deviations of measured dose from indicated dose in CT scanner display were also within tolerance being lower than 20 % for all CT scanners included in this study. The results of this study will be used to establish baselines, providing in this way a standard for comparison which can help in tracking changes of CT equipment performance over time, optimization of imaging protocol and as a guidance on establishing national diagnostic reference levels.

Key wards; Quality control, CT scanner, radiation dose, CT number, uniformity, slice thickness

Speaker: Luljeta Disha (Institute of Applied Nuclear Physics,Unversity of Tirana)

Poster BPU 12 CONGRESS 03.07.2025 ID.Abstract 38.pdf

35 Investigations on hyperspectral images segmentation for cells from cavity serous fluids

Rapid identification of malignant cells from cavity serous fluids (pleural, peritoneal, pericardial, etc.) stand for rich sources of diagnostic information and treatment strategies. High content information embedded in the hyperspectral images taken with CytoViva microscope facility and analyzed with automated statistical algorithms, meet the needs for fast and accurate classification of normal/abnormal cells.
Since the critical step of the process is the precise segmentation of the cells/nuclei in the images, here we compared our approach based on spectral profiles (SPs) and the commercial one in ENVI software. Our home-made code mathematically analyzes reference SPs specific to the nucleus and cytoplasm and extracts several features: maximum intensities and corresponding spectral bands, areas under SPs, skewness and kurtosis of statistical intensity distributions, etc. In ENVI software we used spectral angle mapper which identifies pixels with similar SPs by computing the angle between the vectors.
Acknowledgement: project 8PED/2025, PN-IV-P7-7_1-PED-2024-1895.

Speakers: Mona Mihailescu (National University for Science and Technology Politehnica Bucharest), Andrei Ungureanu (National University for Science and Technology Politehnica Bucharest), Ion Gabriel Vladu (National University for Science and Technology Politehnica Bucharest), Darius Cristea (National University for Science and Technology Politehnica Bucharest), Vlad Fechete

MMihailescu BPU.pdf

36 MRI-Based Characterization of Pelvic Masses: A Physics Perspective

Nowadays, magnetic resonance imaging (MRI) is frequently used in diagnosis, due to its non-invasiveness on the one hand and its high soft tissue contrast on the other. Due to these attributes, MRI is an important method for the characterization of pelvic masses.
This study explores the role of various MRI sequences in characterizing pelvic masses, focusing on the physical principles underlying tissue contrast, signal intensity variations, and diffusion properties. Image quality is closely related to the trade-off-parameters, spatial resolution, signal-to-noise ratio and total scan time. Balancing these factors can be challenging but understanding the physical principles and their applicable limits can aid in their optimal use. These aspects are important in the characterization of pelvic masses where the appropriate selection of sequences and parameters plays a crucial role in differentiating benign from malignant tumors and establishing an accurate diagnosis. The present study examines the impact of sequences selection and parameters optimization on image quality and highlights how the resulting images with different contrast mechanisms (e.g., T1-weighted, T2-weighted, Dixon, Diffusion- weighted imaging, STIR) contribute to the differentiation of various pathologies.
In conclusion, this study provides a deeper understanding of how parameters and sequences influence the quality of acquired images, as well as an integrated medical perspective, contributing to the enhancement of diagnostic and clinical management of pelvic masses.

Keywords: MRI, pelvic tumors, gynecological tumors, diffusion-weighted imaging, Dixon, STIR.

Speaker: Dr Nicoleta Cazacu (Smeeni Chronic Disease Hospital)

37 Phase transitions in bionanocomposites functionalized by nanoparticles

We investigated the thermal and structural behaviour of the phospholipid 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) in the presence of amide-functionalized single-walled carbon nanotubes (af-SWCNTs) using differential scanning calorimetry (DSC) and the surface photo-charge effect (SPCE) 1. Our study focused on the formation of the cooperative unit (CU), which is the basic structural element of the amide-functionalized bionanocomposite across the gel-to-liquid crystal (LC) phase transition, as a function of af-SWCNT concentration. We identified an intermediate state between the gel and LC phases, shaped by steric, van der Waals, and hydrogen bonding interactions. This state was characterized by van’t Hoff (VH) enthalpy, reflecting the cooperativity of the phase transition 2. By analyzing the asymmetry of the DSC endothermic peak and comparing calorimetric and VH enthalpies, we quantified the contribution of VH enthalpy to CU formation.

ACKNOWLEDGMENTS: This work was supported by the project PVU – 58/12.12.2024 /BG-RRP-2.017-0041-C01/ “Development of photonic sensor effects at the interface solid surface/bionanocomposite for detection and control of biogenic impacts” (PhotonSensorEffect) in implementation of an investment under C2.I2: “Increasing the innovation capacity of the Bulgarian Academy of Sciences in the field of green and digital technologies”. This publication has been created with the financial support of the European Union – NextGenerationEU. The sole responsibility for the content of the document lies with ISSP-BAS and under no circumstances can it be assumed that this document reflects the official position of the European Union and MRS-BAS.

References
1 V.I. Pustovoit, et al., Solid State Comm 72, 613 (1989).
2 M.H. Chiu et al., J Pharm Bioallied Sci. 3, 39 (2011).

Speaker: Yordan Marinov

38 Polarization Mapping of Elements with Spatially-Varying Birefringence

Polarization mapping refers to the process of measuring and visualizing the spatial distribution of the polarization state across a light beam. It reveals how the polarization varies from point to point in space showing, e.g., regions with radial, azimuthal, or elliptical polarization [1-3]. Polarization mapping is essential in analyzing vector beams, structured light, and beams with spatially varying polarization such as those produced by q-plates or metasurfaces. It typically involves elements like rotating polarizers, wave plates, and imaging detectors to reconstruct the Stokes parameters or polarization ellipses across the beam profile.

In this work, however, we report a method for parallel determination (mapping) of the polarization change introduced by an unknown optical element using arrays of linearly polarized Gaussian beams. More precisely, we present an experimental technique for polarization mapping of birefringent elements generating polarization vortices, such as vortex retarders. The approach is applicable also for clear determination of the polarization response of spatial light modulators. Experimental data will be presented and discussed, focusing on benefits and the limitations of the demonstrated approach.

We acknowledge funding of the Bulgarian National Science Fund (project KΠ-06-H78/6). The work was also supported by the Bulgarian Ministry of Education and Science as a part of National Roadmap for Research Infrastructure, project ELI ERIC BG and by the European Regional Development Fund under "Research Innovation and Digitization for Smart Transformation" program 2021-2027 under the Project BG16RFPR002-1.014-0006 "National Centre of Excellence Mechatronics and Clean Technologies". L.S. and A.D. were also supported by the European Union NextGenerationEU through the “National Recovery and Resilience Plan of the Republic of Bulgaria, project BG-RRP-2.004-0008-C01”.

REFERENCES
[1] X.Wang, F. Yang, J. Yin, “Mapping the polarization distribution of arbitrary vector polarization beam”, Optik, 144, 124-131, (2017).
[2] B. Schaefer, E. Collett, R. Smyth, D. Barrett, B. Fraher, “Measuring the Stokes polarization parameters” Am. J. Phys.75 (2), 163–168 (2007)
[3] J. Yang, D. Lin, D. Bao, S.Tao, “Pixel level control of amplitude, phase, and polarization of an arbitrary vector beam” Appl. Phys. Lett., 121 (19), (2022).

Speaker: Dr Lyubomir Stoyanov (Department of Quantum electronics, Faculty of Physics, Sofia University "St. Kliment Ohridski")

39 Sensing Interactions of Chlorella Vulgaris and Model Lipid Membranes Using Gold and Carbon Screen-Printed Electrodes

The main objective of this study is to evaluate electrochemical gold and carbon screen-printed electrodes (SPEs) as potential platforms to investigate interactions of lipids model systems with biologically important molecules.
The system under examination consists of model lipid membrane and Chlorella Vulgaris microalgae solution. Two types of working electrodes were used – gold and carbon, and their advantages and restrictions have been analyzed. The applied electrochemical methods were cyclic voltammetry and electrochemical impedance spectroscopy. The behavior of the model membrane system was studied in response to three different concentrations of Chlorella whole cell samples, as well as over time. Our investigations reveal that the Chlorella Vulgaris sample interacts significantly with the model membrane. The observed with cyclic voltammetry (CV) reduction peaks express a shift in voltage with different concentrations of the substance. The response of the membrane system differed significantly between the two electrode types. On the gold electrode, membrane disruption occurred and did not recover over time, indicating strong and possibly irreversible interaction.
In contrast, the carbon electrode allowed the system to gradually return to its original state, suggesting transient processes. This suggests that the lipids interact with the carbon electrode and the microalgae remains in the solution.
Those changes were confirmed by the electrochemical impedance data. Suitable electrochemical equivalent circuits were found to represent the processes on the electrodes interface. The reported results show that gold SPEs, compared to carbon ones, are more suitable for studying the interactions of lipid model systems and Chlorella Vulgaris solution.
The authors are thankful to MU-Varna, project No. 23003 “Development of a green method for the production of phycocyanin from Spirulina with potential applicability in pharmacy and food technologies”.

Speaker: Desislava Popstoyanova (Medical University - Varna)

40 Spectrophotometric Evaluation of Sun Protection Factor (SPF) of Wild Sideritis raeseri under Variable Solvent and Temperature Conditions

Skin cancer, classified into basal cell carcinoma (BCC), squamous cell carcinoma (SCC) (both nonmelanoma), and melanoma, is the most prevalent form of cancer worldwide. The pathogenesis of skin cancer is multifactorial, but the main causative agent is ultraviolet (UV) radiation[1]. The growing interest in natural UV photoprotective agents highlights the significance of phytochemicals as potential sunscreens[2]. This study evaluated the endemic Albanian mountain tea (Sideritis raeseri) for its UV photoprotective properties, specifically the SPF, under various solvent environments[4], temperature storage, and at different times utilizing spectrophotometry (UV-VIS 756s ) and the Mansur method for SPF estimation.
The aqueous extracts of wild S. raeseri were first centrifuged, then filtered, and mixed in two different Erlenmeyer flasks with distilled water and a mixture of distilled water-ethanol as solvents in a ratio of 1:4 v/v. UV absorbance was measured for two different solvents (water and a mixture of water-ethanol) at different temperatures and over six consecutive days, in the 290–320 nm range, a critical window for erythemogenic UVB radiation[3].
Results showed that in the tea aqueous extracts stored at ambient temperature (29-31°C), the SPF value dropped gradually from 26.426 (the first day) to 17.930(sixth day).In contrast, the refrigerated tea aqueous extracts (4-6°C) dropped from 26.426 to 22.469, suggesting enhanced stability and photoprotective capacity at lower temperatures. Conversely, in the mixture of water-ethanolic solvent at ambient temperature, the SPF value drops from 23.281 to 13.387, while in the refrigerated one, the drop was from 23.281 to 16.958. These results underscore the dual role of temperature and solvent polarity in modulating the photoprotective efficacy of S. raeseri. The notable shield life preservation in SPF values at refrigerated conditions could be attributed to the reduced photodegradation of phenolic compounds. Our analysis confirms that the choice of solvent and temperature during extraction significantly affects the photoprotective potential of herbal extracts [4,5]. Refrigeration or cool storage helps preserve both chemical integrity and biological efficacy of phenolic compounds.
The SPF values suggest that S. raeseri extracts could be a valuable natural additive in topical sunscreen formulations where solvent selection and storage conditions must be optimized for maximal efficacy. It has enhanced performance in refrigerated water solvent extracts and less in water-ethanol solvents. This is particularly relevant for formulations seeking to minimize synthetic UV filters due to concerns over allergenicity and environmental toxicity [5].
Keywords: Sideritis raeseri, Sun Protection Factor (SPF), UV photoprotection, solvent effect, temperature stability
References
[1] Fabris MR, et al., An. Bras. Dermato.l 87, 36-43 (2012). [2] Mary K. Montes de Oca et al., Photochem. and Photobiol., 93, 956–974(2017)
[3] A. Mansur et al., An. Bras. Dermatol. 61, 121 (1986).
[4] https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32009R1223 Official Journal of the European Union, REGULATION (EC) No 1223/2009
[5] C. Stiefel and W. Schwack, Intern. Journ. of Cosmet. Scie., 37, 2–30 (2015)

Speaker: Dr Emil Xhuvani (University of Tirana, Physics Department)

41 Structural and optical properties of tin oxide thin films

Tin oxide thin films with different thicknesses were deposited under vacuum on glass substrates by thermal evaporation technique. Transmission electron microscopy was used to study the structural properties of thin films. Atomic force microscopy method was used to study the surface morphology of thin films of tin oxide. The optical constants such as the absorption coefficient and optical band gap energy of thin films were obtained from the analysis of the experimental recorded transmission spectral data over the wavelength range 300-1100 nm. The correlations between optical constants and the structure of tin oxide thin films are discussed.

Speaker: Simona Condurache-Bota (1Dunarea de Jos University of Galati, Faculty of Sciences and Environment; 2Dunarea de Jos University REXDAN research infrastructure, Galati, Romania)

abstract_BPU_2025_Tigau_Condurache_et_al.pdf

42 The effects of red/infrared light treatment on the total protein concentration in lymphocytes

The effectiveness of red light therapy (RLT) on cellular activity is important in determining if its usage is suitable for the treatment of various health conditions.
In order to better understand the molecular and metabolic mechanisms related to RLT, our preliminary study of the effect of LED light sources 660 nm and 850 nm on the proliferation of human lymphocyte cells was further extended to analyze its effect on the synthesis of cellular enzymes.
Using the Bradford method, the total concentration of proteins in lymphocytes was monitored for different time parameters and conditions of exposure and in relation to the untreated (non-irradiated) control cells.
Our results show a higher protein concentration for all irradiated samples when compared to the unirradiated samples and it was especially increased for multiple exposures to red/infrared light.
Since the used method cannot answer whether the increased protein concentration has positive or negative connotations, it is important to continue the research and include additional methods that test oxidative stress and the structure of chromosomes on a larger number of samples in order to gain additional understanding of the beneficial impact of RLT on lymphocyte cells.

Speaker: Amela Softic

Softic online poster presentation.pdf

43 The SPF Determination of Albanian Sideritis Raeseri Aqueous Solutions And Correlation With Phenolic Compounds

Abstract
The rise in skin cancer incidence, notably melanoma and nonmelanoma types, is a significant global public health concern. This increase has been attributed to greater ultraviolet (UV) exposure and insufficient use of photoprotection, particularly in older adults and men [1]. While synthetic sunscreens are widely used, concerns about their safety and environmental persistence have motivated a search for natural alternatives. The wild Albanian “mountain tea”, Sideritis raeseri belongs to Lamiaceae family was studied in this paper for its potential protective effects against direct sunlight, particularly UV radiation, and indirectly through its antioxidant properties with the “in vitro” method. This plant, typically found at elevations above 600 meters, is a mostly perennial herb that flourishes in calcareous, well-drained, slightly alkaline soils. This study evaluates the UV protective properties of S. raeseri through in vitro Sun Protection Factor (SPF) determination, correlating photoprotective activity with phenolic content. Aqueous extracts were prepared from dried aerial parts, leaves, flowers, stems, and the whole plant, following standardized infusion, filtration, and centrifugation protocols. UV-VIS spectrophotometry (290–320 nm, 5 nm intervals) was conducted on 20% v/v dilutions (5% for leaves, corrected by dilution factor), and SPF values were calculated using the Mansur equation [2].
Results revealed that leaf extracts exhibited the highest SPF (43.17), followed by flowers (13.14), the whole plant (8.29), and stems (4.92). These variations aligned strongly with phenolic content, as confirmed by a Pearson correlation coefficient (r = 0.958, p < 0.01). Phenolic compounds such as Carvacrol (36.7%) and Thymol (0.5%) known for their aromatic rings and hydroxyl groups, contribute to effective π → π* transitions responsible for UV absorption [3]. A marked absorption peak at 278–279 nm was observed, likely representing phenolic content and affected by aqueous solvent polarity, which causes a bathochromic shift when compared to spectra in methanol [4].
In addition to direct UV absorption, antioxidant activity plays a crucial secondary role in protection by neutralizing free radicals produced under UV exposure. Previous studies have established that phenolic-rich Sideritis species, especially the leaves, exhibit high antioxidant capacity, further enhancing their photoprotection efficacy [5].
In conclusion, this study supports the use of Sideritis raeseri, especially its leaf extracts, as a promising natural ingredient in sun-protective cosmetic formulations. The dual mechanism, direct UV filtering and antioxidant defense, suggests strong potential for safe, plant-based sunscreen development.
Keywords: Sideritis raeseri, SPF, UV protection, phenolic compounds, antioxidant, Mansur method

Speaker: Dr Emil Xhuvani (University of Tirana, Physics Department)

44 Fabrication and characterization of novel iron oxide aeromaterial

In this work, we report the fabrication of a novel aeromaterial based on Fe₃O₄, synthesized via spray pyrolysis and drop infiltration techniques. The process involves the deposition of Fe₃O₄ onto sacrificial ZnO microtetrapod templates. The precursor solution consisted of 0.15 M FeCl₃ dissolved in ethanol. For the spray pyrolysis approach, a custom-built setup was used, with the substrate maintained at 480 °C and the deposition time being 3 minutes, yielding Fe₃O₄ thin films with an approximate thickness of 400 nm. In the drop infiltration method, 150 μL of precursor solution was droped on the ZnO microtetrapods substrate at a rate of one drop per second, at room temperature. The samples were subsequently annealed at 500 °C for one hour in air in order to improve the material’s crystallinity and eliminate residual chlorine. The ultraporous structure of Fe₃O₄ was achieved by selectively etching the ZnO templates using 0.1 M citric acid. The final three-dimensional architecture was obtained through a controlled drying process in a lyophilizer at –55 °C for 8 hours. The structural characterization of the material using XRD showed the presence of both Fe3O4 and ZnFe2O4 mixed phases. The photoelectrical characterization at 150 K and 300 K and excitation using an Nd:YAG laser (355 nm) has shown the remanent photoconductivity, with a more pronounced effect at lower temperatures.

Speaker: Catalin Creciunel (Technical University of Moldova)

45 Functionalization of Titanium-based surfaces with 3D polymeric microstructures fabricated by Laser Direct Writing via Two Photon Polymerization

Titanium-based implants are frequently used in medical practice for bone-associated injuries and disorders. However, the osteointegration of Titanium is limited by its lack of bioactivity. To overcome this drawback, in this study we functionalized titanium-based surfaces with 3D polymeric microstructures fabricated by laser direct writing via two-photon photopolymerization (LDW via TPP), which improved the osteogenic response of osteoblast-like cells . The microstructures consisted of 64 vertical microtubes, arranged on 5 layers of different heights ( from 10 to 170 μm), having a porosity ranging from 94% to 99% (consistent with the upper limit porosity of natural bone). The microstructures were made from a biocompatible photopolymerizable photopolymer (Ip-Dip). MG-63 osteoblast like cells were seeded on the 3D polymeric microstructures and analyzed at 1, 2, 7 and 14 days. For comparison, we also studied the behaviour of MG-63 cells seeded on non-functionalized Titanium-based surfaces. Scanning electron microscopy (SEM) investigations showed that the 3D polymeric microstructures promoted the three-dimensional organisation of the seeded cells, which is characteristic of bone tissue, whereas the cells on non-functionalized titanium surfaces were arranged only in 2D. In addition, SEM analysis evidenced earlier signs of collagen fibrils synthesis (namely after only 7 days) in the cells from Titaniun surfaces functionalized with 3D polymeric microstructure, as compared to slower collagen synthesis (after 14 days) for cells on non-functionalized Titanium. Moreover, Energy Dispersive X-ray Spectroscopy (EDX) indicated incipient signs of mineralization, as shown by early-stage presence of calcium and phosphorus within seeded cells, that for Titanium-based surfaces functionalized with 3D polymeric microstructureshat started from two weeks of cells cultures. Finally, we determined the traction forces exerted by the osteoblast cells on the 3D polymeric microstructures, given that these forces are known to strongly influence the cellular behaviour. To this end, we performed finite element analysis (FEA) simulations in the FEBio Studio environment. First, we simulated, as close as possible ,the in vitro experiment, using the mechanical properties of Titanium and of Ip-Dip photopolymer. The displacements of microtubes’s tips during in vitro experiments were measured by SEM (namely, 17.6 ± 0.2 μm displacement for 130 μm microtubes’s height). The simulation indicated that the traction force required to induce such a displacament was of approximately 600 μN, which is approximately three orders of magnitude higher than the traction forces reported for osteoblast cells in vitro. We believed that this difference arrised from the fact that the mechanical properties of Ip-Dip photopolymer were much different than the values of materials encountered in vivo. As such, to validate our approach, the simulation was repeated using the mechanical parameters specific to bone extracellular matrix, in which case the estimated force was of 5.5 nN – a value consistent with the traction forces reported in the literature. In all, these results highlight the promising premises of the proposed approach of functionalizing titanium-based surfaces with 3D polymeric microstructures fabricated by LDW via TPP , to support the osteointegration process of bone implants and, consequently, to improve the patient’s quality of life.

Speaker: Roxana Gabriela Ghita (Center for Advanced Laser Technologies (CETAL), National Institute for Lasers, Plasma and Radiation Physics, Magurele-Ilfov, RO-077125, Romania)

46 Synthesis, optical and morphological characterization of different sizes gold nanoparticles for the development of viromimetic particles

Nanoparticles have gained significant interest in various scientific fields due to their unique physicochemical properties, adjustable size and potential for targeted functionalization.
In comparison to bulk materials, these particles exhibit different characteristics, such as quantum effects, large specific surface area and enhanced optical, magnetic and mechanical behavior.

The aim of this work is the synthesis of gold nanoparticles (GNPs) for the development of cargo loaded viromimetic nanoparticles, followed by their characterization and assembly with target biomolecules. Virus like particles (VLPs) are engineered to be used in medical applications such as targeted drug delivery or gene therapy.

We report results of the studies regarding the influence of fabrication parameters, namely the size and shape of the gold nanoparticles, on the optical and morphological properties. The particles were synthesized using different concentrations of tannic acid leading to a shift in the nanoparticles’ sizes. Thus, stable gold nanoparticles (Au NPs) obtained by this method were found to have average sizes between 8 and 20 nm, depending on the reducing agent’s concentration. The optical properties were evaluated using UV-Vis absorption spectra of gold nanoparticles solutions and the morphological evaluation was made by using scanning electron microscopy (SEM) technique.
For determination of physical parameters associated with virus shell self-assembly process, the method initially used was Surface Plasmon Resonance (SPR) for gold nanoparticles and protein in order to monitor the molecular interactions of the assembly process in real-time.

Speaker: Maria-Lorena Jinga (International Center for Advanced Training and Research in Physics (CIFRA), Magurele, Romania, National Institute of Materials Physics (NIMP), Magurele, 077125, Romania, University of Bucharest, Doctoral School of Physics, Magurele, Romania)

EPS-TIG hands-on session “Frontier of Quantum Technologies”

Interdisciplinary Physics, Mathematical and Computational Methods

47 Decoding the Geodynamo: Quantitative Dependence of Magnetic Field Diagnostics on Dimensionless Control Parameters

Understanding the generation and evolution of planetary magnetic fields requires a quantitative grasp of how key dynamo diagnostics respond to variations in fundamental hydrodynamic control parameters. In this study, we perform a systematic numerical investigation of convection-driven dynamo models in rotating spherical shells, using a suite of simulations spanning several orders of magnitude in Ekman number (E), Rayleigh number (Ra), and magnetic Prandtl number (Pm). Our primary aim is to unravel the dependencies of magnetic energy, dipolarity, field symmetry, and temporal variability on these dimensionless parameters, which collectively govern the balance of forces and transport mechanisms in the system. We quantify the scaling laws of magnetic energy and dipole tilt angle as functions of Ra and Pm, revealing sharp transitions from stable, Earth-like dipoles to multipolar and fluctuating regimes. Spectral diagnostics further demonstrate how kinetic and magnetic energy cascade characteristics evolve with decreasing E, indicating the emergence of rotationally constrained turbulence and quasi-geostrophic behavior. By bridging local and global diagnostic perspectives, this work offers a refined parameter map for dynamo behavior and delineates the physical mechanisms that control magnetic field morphology. Our findings contribute to constraining geophysical models of the Earth's core and guiding future studies toward more Earth-relevant regimes.

Speaker: Klaudio Peqini (Physics Department, Faculty of Natural Sciences, University of Tirana)

Peqini_et_al_paper_2025.docx

48 UAV LiDAR and Photogrammetry for Accurate 3D Mapping and Modeling in Environmental Physics

UAV-based LiDAR equipment was designed as a high-performance drone equipped with a LiDAR system, which operates on electric batteries with a period of flight up to 45 minutes (with a payload) and can transport equipment with an operational weight of 27 kg, the maximum weight of take-off being up to 50 kg. The drone control is done through an advanced system that allows monitoring its position and image processing in real time. The drone can be manually piloted, assisted or fully autonomous within a range of about 50 km. The drone is incorporated with a Geosun GS 100C LiDAR system, which is a complete and compact air LiDAR solution specially designed for UAV integration. Equipped with Livox Avia sensor, this system offers a detection ray of up to 450 meters, multiple returns and an accuracy of up to 10-15 cm at average flight altitudes. With a high precision GNSS/IMU and an integrated 26 MP camera, Geosun GS 100C allows the simultaneous processing of LiDAR data and georeferential images, being ideal for mapping, topography, infrastructure inspection and 3D modeling. The drone was built to operate under difficult weather conditions such as winds up to 12 m/s and temperatures between -20 °C and +55 °C.
The technology offers high-resolution mapping, vegetation penetration, and the ability to generate accurate 3D terrain models by leveraging integrating UAV LiDAR terrain mapping with real photogrammetry data, and its application in terrain mapping and 3D photogrammetry modeling, fast creation of precise digital elevation map models and in monitoring based on the airborne LiDAR and photogrammetry measurements for rapid inspection, assessment, and environmental data collection and analysis.
We present a detailed analysis based on a 3D model generated and visualized in the CloudCompare, an open-source software for processing 3D point clouds. The obtained precise image represents a developing urban area, located in the vicinity of the “Alexandru Ciubotaru” National Botanical Garden (Institute) in Chisinau city, the image being obtained through photogrammetry and LiDAR scanning. The study highlights the characteristics of this point cloud and its potential applications in urban and environmental analysis. We were able to underline two distinct areas: an urban area that contains several tall buildings, some under construction, and a second area represented by the National Botanical Garden, which contains well-defined paths, trees of various sizes and a terrain with varied relief. The model retains a high degree of detail for this natural habitat, which allows precise topographic analysis. Using aerial imagery and LiDAR scanning have proved to be an accurate method for digital reconstruction of the urban and natural environment, in environmental monitoring and urban ecosystem management, as well as in the analysis of terrain changes caused by natural or anthropic factors.
Authors gratefully acknowledge support provided by the NATO SPS G6140 APRIORI project and the Ministry of Education and Research (MD) through the grant number 011210.

Speaker: Dr Sprincean Veaceslav (Moldova State University)

BPU12_abstract.docx

49 Generalization of a special class of interacting 2d BF models to an arbitrary even spacetime dimension from a BRST cohomology-based approach

Here, we generalize the 2d description of gravity theory via a self-interacting class of topological BF models to an arbitrary, even spacetime dimension, greater or equal to 8 (the 4d and 6d cases have been analyzed previously and were shown to lead to several types of couplings). Our methodology relies on a variant of deformation method based on a local cohomological BRST approach in the framework of the antibracket-antifield formalism computed in connection to a free, non-interacting collection of BF models with a special field spectrum. This spectrum is restricted such that to reveal only the interaction vertices that strictly generalize the 2d findings and thus ‘hide’ the expected zoo of vertices allowed in the case of a larger, for instance maximal BF field spectrum. If we denote the (even) spacetime dimension by 2k>6, then the restricted BF field spectrum leading to the searched for generalized vertices comprises only two collections of pairs of fields of minimum-maximum form degrees with respect to the maximally allowed spectrum, namely, (0,1) and (k-1,k). The main features of the generalized, interacting BF model can be synthesized into: 1. the self-couplings are parameterized by a unique set of functions allowed to depend at most on the undifferentiated zero-forms from the BF field spectrum with special symmetry properties (antisymmetric for k odd and symmetric for k even), 2. these parameterizing functions are not restricted by further conditions, normally needed to ensure the consistency of first-order deformations to all orders in the coupling constant (like in the initial 2d setting), and 3. all the relevant (gauge) quantities of the coupled model, including the interaction vertices, are nonlinear and may display some very general features related to the deformed set of generating gauge symmetries (an open gauge algebra and some on-shell reducibility relations) as long as the parametrizing function set is not further constrained (such as having a polynomial form).

Speakers: Prof. Constantin Bizdadea (University of Craiova, Romania), Eugen-Mihaita Cioroianu (University of Craiova, Department of Physics), Solange-Odile Saliu (University of Craiova, Romania)

50 Hamiltonian origins of a special class of interacting BF models in an arbitrary even spacetime dimension

Starting from the Lagrangian formulation of a special class of interacting topological BF models in an arbitrary even spacetime dimension deduced previously by a particular deformation method, here we investigate its Hamiltonian roots in the light of the general result according to which each theory with nontrivial gauge symmetries at the Lagrangian level always originates in a system subject to at least a set of first-class constraints (and possibly also some second-class ones, although not necessarily). The coupled model and its free (non-interacting) limit are compared and contrasted within the Hamiltonian setting. We find that the Hamiltonian properties of the two systems (the self-coupled one and its free limit) are completely complementary in the sense that if one displays a first-class constraint set with an open gauge algebra that is on-shell reducible, then the other exhibits an Abelian algebra and a set of reducibility relations that holds off-shell at the level of its corresponding first-class constraints.

Speakers: Constantin Bizdadea (University of Craiova), Prof. Eugen-Mihaita Cioroianu (University of Craiova, Department of Physics), Solange-Odile Saliu (University of Craiova, Romania)

51 Geometric structures for various fermionic fields from a Faddeev-Jackiw argument

Invoking the specificity of first-order dynamics for fermionic fields and using a Darboux argument, one avoids the Dirac prescription for inferring the geometric structures of various fermionic fields on a 4-dimensional Minkowski spacetime.

Speaker: Stefan Manolescu (University of Craiova)

52 Vortices and water waves

The study of rotational flows of an inviscid incompressible fluid with free boundary is of high theoretical and practical interest (e.g., the evolution of surface waves on the ocean, their approximation by model equations, the dynamics of wave interactions). The vorticity is the key quantity in the analysis of the fluid motion.

We consider a two-dimensional water-wave problem with a general non-zero vorticity field in a fluid volume with a flat bed and a free surface.

The nonlinear equations of motion for the specified surface and volume variables are expressed in closed form. These equations describe a complicated interaction between the surface and the volume, so that a simple reduction of the model only to the surface variables is not possible.

As an example we present a point vortex and its interaction with the free surface of the fluid. In the small-amplitude long-wave Boussinesq and KdV regimes, we obtain a simplified system of coupled equations for the motion of the vortex and the time evolution of the free surface.

References

D. Ionescu-Kruse, R. Ivanov, Nonlinear two-dimensional water waves with arbitrary vorticity,Journal of Differential Equations 368 (2023) Pages 317--349,
https://doi.org/10.1016/j.jde.2023.05.047

Speaker: Rossen Ivanov (Technological University Dublin)

Nuclear Physics, Energy Science and Technology, Accelerators and beams

53 Differential Cross-sections Measurement of the 12C(d, p0)13C Reaction

In this work we present a new and reliable set of differential cross-sections for 12C(d, p0)13C reaction in the energy range of 600 –200 keV at a detection angle of 165º, all in the laboratory reference system.
Several experimental cross-section datasets for the 12C(d, p0)13C (Q=2.73 MeV) reaction have been published at various deuteron beam energies and different angles of detection [1-3]. The observed discrepancies between the existing cross section datasets, especially at resonances, have motivated us to conduct new measurements.
All measurements were conducted using the deuteron beam of the 3 MV Van de Graaff electrostatic accelerator of Nuclear Science and Technology Research Institute (NSTRI) in Tehran. The energy of the incident deuteron beam was varied with 30 keV energy steps off-resonance regions and 2 keV steps in the narrow resonance regions. The backscattered protons were collected by an ion implanted Si detector at a scattering angle of 165º with respect to the beam direction.
Two thin-targets, of natural isotopic composition, were used to measure the cross sections in different energy regions: a C/Ag target for the deuteron energy region Ed =1.25-1.5 MeV where the resonances are narrower, and a C3H6N6/Ag target for the rest of the deuteron energies [4].
The present data were compared with the existing experimental data in literature and discussed.
The comparison our data with the evaluated differential cross sections obtained from the online R-matrix calculator SigmaCalc (http://sigmacalc.iate.obninsk.ru) reveals the there is a good agreement in shape and values of both excitation functions. The obtained resonances at Ed = 948, 1190, 1313, 1446 and 1782 keV, are in close agreement with excited states of 14N compound nucleus.
The overall systematic uncertainty of the measured cross section data was estimated to be better than 5%.
References:
[1] M. Kokkoris et al. Nuclear Instruments and Methods in Physics Research B 249 (2006) 77.
[2] D. Abriola, A.F. Gurbich, M. Kokkoris, Nuclear Instruments and Methods in Physics Research B 301 (2013) 41.
[3] J.A.R. Pacheco de Carvalho, A.D. Reis, Nucl. Instr. Meth. Phys. Res. B 266 (2008) 2263.
[4] A. Jokar, Hafez Taghipour Aslani, Nucl. Instr. Methods Phys. Res. B557, (2024) 165549.

Speaker: Dr Hafez Taghipour Aslani (ELI-NP)

54 FLUKA-simulations for the optimization of an ion irradiation platform for radiation hardness studies

An experimental platform dedicated to radiation hardness experiments is currently under development at the 3 MV Tandetron™ from IFIN-HH. Following installation, the system will undergo commissioning through monitoring of the response of CARD-SAT satellite components exposed to extreme irradiation conditions, such as high dose and flux. A key aspect of the setup involves detailed FLUKA simulations, which are being used to evaluate proton transport, energy deposition profiles including the Bragg peak, and the generation of secondary particles that may influence Total Ionizing Dose (TID) and Single Event Effects (SEE). This tool support accurate assessment of Linear Energy Transfer (LET) distributions and radiation effects on space-grade electronics.

Speaker: Marta Petruneac (Horia Hulubei National Institute for Physics and Nuclear Engineering)

55 New insights on the nuclear matter behaviour using CBM experimental set-up

At GSI Darmstadt (Germany) there is in construction a new and very performant accelerator system, namely the Facility for Antiproton and Ion Research (FAIR). The performances of this facility, related to the beam intensity and energy, interaction rate, around 1 MHz, etc will provide remarkable research opportunities in Nuclear and Particle Physics, in Atomic Physics and Nuclear Astrophysics, as well as in materials research, plasma Physics and radiation Biophysics, including developments of novel medical treatments and applications for space science. This accelerator system will produce, too, high-intensity secondary beams using s a large acceptance Superconducting Fragment Separator (SFS). Therefore, major experiments have been proposed during the time, as: NUSTAR (NUclear STructure, Astrophysics and Reactions), PANDA (AntiProton ANnihilation at Darmstadt), at the High-Energy Storage Ring (HESR), APPA and CBM (Compressed Baryonic Matter).
The CBM Experiment includes detector systems for investigation of the high-energy heavy-ion collisions. These investigations will help in the knowledge of the properties of very dense and hot nuclear matter formed in the overlapping region of the two colliding nuclei. Interesting connections among different fields will be possible. As members of this collaboration, we are involved in different research directions of the collaboration. Some of the most interesting predictions obtained during two decades of participation at the activities of the CBM Collaboration are included in this work. These results reflect de connections between collision geometry and collision dynamics, influences of the thermodynamic equilibrium of the conditions in the participant region and the equation of state, nuclear matter flow and specific phases etc

Speaker: Alexandru Jipa (1University of Bucharest, Faculty of Physics, Department of Structure of Matter, Earth and Atmosphere Physics, Astrophysics)

56 Transition densities in odd-A nuclei

We present new analytical results on transition densities and charge radii of odd-even spherical and transitional nuclei obtained using a microscopic approach. The results show a pronounced influence of the collective modes in the ground and excited states. Our main contribution is assessing the new terms and exemplifying their effects on several nuclei in the cadmium region.

Speaker: Stoyan Mishev (New Bulgarian University and Institute for Advanced Physical Studies)

57 Electromagnetic Field Measurements Around High-Voltage Substations in Residential Areas: A Case Study from Tirana

The operation of high-voltage electrical substations in or near residential areas has raised public concern about potential adverse health effects from chronic exposure to power-frequency electromagnetic fields. This study aims to assess the intensity of electromagnetic fields around several substations in Tirana city, Albania, and evaluate compliance with international safety guidelines. Measurements of the electric field strength (E, in V/m) and magnetic flux density (B, in µT) were carried out at multiple points and distances around five representative substations using an isotropic field analyzer (Narda EHP-50F probe, 1 Hz–400 kHz range). The measurement campaign spanned different times of day (08:00–18:00) to capture typical operating conditions. The resulting data indicate that the electromagnetic field levels around these substations remain below the reference limits recommended by ICNIRP for general public exposure (5 kV/m for electric fields, 100 µT for magnetic fields). Peak electric field values on substation perimeters approached ~5 kV/m, while peak magnetic field values were on the order of a few µT, which is only a few percent of the allowed limit. These results provide evidence that typical urban substations, even when located near populated areas, do not exceed established safety limits, thereby offering reassurance regarding public electromagnetic exposure. The study’s methodology and findings serve as a basis for informed guidelines and communication about environmental electromagnetic fields around power infrastructure.

Speaker: Margarita Kuqali (Polytechnic University of Tirana, Albania)

58 In memoriam Professor Dr. Călin BEȘLIU

Professor Dr. Călin BEȘLIU (23.VII.1930-30.XI.20204) is one of the remarkable Romanian physicists and was, for many decades, an excellent Professor for the students of the Faculty of Physics from the University of Bucharest. He dedicated his activity to Physics, Nuclear and Particle Physics, mainly, both in research and academic fields. His activity was complex, diverse and intense, and, therefore, he was in the top of the many research fields opened at the national and international levels, fact reflected by the scientific data bases. He worked from Neutron and Reactor Physics to Relativistic and Ultrarelativistic Nuclear Physics with significant results at the national and international levels. The very deep knowledge of the fields permitted him to transfer to his students. Therefore, he conducted more than 400 hundred of diploma and dissertation theses, as well as more than 35 PhD theses. He was disciple of Academician Professor Dr. Horia HULUBEI, the founder of the Atomic and Nuclear Physics fields in Romania.
On July 23rd Professor Dr. Călin BEȘLIU could have 95 years. This work is an homage of the entire life and activity dedicated to Physics by Professor Dr. Călin BEȘLIU.

Speaker: Alexandru Jipa (University of Bucharest, Faculty of Physics, Department of Structure of Matter, Earth and Atmosphere Physics, Astrophysics)

Plasma, Statistical and Nonlinear Physics

59 From laboratory to space: proton irradiation of carbonaceous dust analogues deposited by atmospheric pressure plasma

‘Fluffy’ hydrogenated amorphous carbon (a-C:H) was synthesized using a dielectric barrier discharge plasma, driven by nanosecond high-voltage pulses at 1 kHz frequency in a helium–butane mixture [1,2,3]. The a-C:H samples were characterized by various microscopy and spectroscopic techniques. The results show that a-C:H samples exhibit infrared absorption features that closely match those observed for carbonaceous dust in the IRAS 08572+3915 galaxy. We discuss the nano- to microscale structure of the analogues and a method to derive the hydrogen-to-carbon (H/C) from FTIR data, corelated with results from three different experimental characterization techniques. By relying on the average H/C value determined through mass spectrometry and Raman spectroscopy, the absorption strength values were constrained to best match the dust analogue, allowing the calculation of the H/C ratio from the infrared spectra. The analysis indicates that the dust analogue predominantly consists of a hydrogen-rich aliphatic network with small, isolated aromatic regions.
The a-C:H dust analogue was then irradiated with 3 MeV protons and analysed ex situ. Morphological and chemical changes were observed, including variations in H/C, CH₂/CH₃, and sp²/sp³ ratios, indicating dehydrogenation and graphitization. Proton bombardment shifted the initial location of a-C:H in the hydrocarbon ternary phase diagram toward the region defined by IRAS 08572+3915 observations. The decay of the 3.4 μm band due to proton fluence was used to calculate CH destruction cross-sections, which are consistent with the direct effects of cosmic rays on the disappearance of this feature.

[1] I. C. Gerber, I. Mihaila, V. Pohoata, A. Sandu, C. Agheorghiesei, L. V. Soroaga, … & I. Topala, The Monthly Notices of the Royal Astronomical Society 538, 266 (2025).
[2] I. C. Gerber, A. Chiper, V. Pohoata, I. Mihaila & I. Topala, The Proceedings of the International Astronomical Union 15, 237 (2019).
[3] B. Hodoroaba, I. C. Gerber, D. Ciubotaru, I. Mihaila, M. Dobromir, V. Pohoata, & Topala, I. (2018). The Monthly Notices of the Royal Astronomical Society 481, 2841 (2018).

Speaker: Ionut Topala (Alexandru Ioan Cuza University of Iasi, Faculty of Physics)

60 Coupled semidiscrete solitonic equations of the first multiplicative Bogoyavlensky and its soliton solutions

A coupled extension of the first multiplicative Bogoyavlensky equation is analyzed using the Hirota bilinear formalism. Considering an appropriate substitution, we first construct the Hirota bilinear form. Once we coupled semidiscrete system is written in terms of the Hirota operator, we construct the 3-soliton solutions. The existance of the multi-soliton solutions, obtained via generalization, proves the complete integrability of the analyzed system.

Speaker: CORINA NICOLETA BABALIC (University din Craiova)

61 Classical and Quantum Description of the Kapitza–Dirac Effect

In this presentation, we explore the classical and quantum descriptions of the Kapitza-Dirac effect: the scattering of particles, such as electrons or atoms, by a standing wave electromagnetic field. In the classical case we integrate the equation of motion, both in its exact form and using the ponderomotive approximation, for a statistical ensemble of electrons. We present graphical representations of the final momentum distribution as a function of the particles' initial positions. For the quantum description, we integrate the Klein–Gordon equation for a charged particle interacting with the standing wave. Using a method inspired by the work of Gavrila [1], we show that the Klein–Gordon equation reduces to a linear Goursat problem, which we solve numerically. We present a comparison between the classical and quantum results.

[1] M. Gavrila, “Crossed-laser-beam solutions for the Klein-Gordon equation”, Phys. Rev. A 99, 012120 (2019)

Speaker: Darius-Matei Banu (University of Bucharest)

62 About test particle diffusion in a sheared magnetic field

In our paper we have studied the transport of particles moving in a sheared stochastic magnetic field considering also the particle collisions. The transport is influenced by the collisional Kubo number and the shear Kubo number that gives an asymmetry of the trajectories. We have studied only a few cases given by the collisional Kubo number and different values of the shear Kubo. An analogy with some characteristics of the interaction between patients and the medical system was presented.

Speaker: Marian Negrea (Department of Physics, University of Craiova, Association EURATOM-MEC, Romania)

63 Exact critical temperature of Ising models with external field

On the squares of two lattices, square and 4-8 lattice, besides the interactions between nearest neighbour spins, additional diagonal and four-spin interactions are present. Under some restrictions, by introducing central decorating spins on each square, the square lattice is transformed to another square lattice, while the 4-8 model becomes a square lattice with decorated bonds. Exact critical temperatures are obtained. In the case of antiferromagnetic interactions this is also possible in the case when an external magnetic field is acting on all lattice sites.

Speaker: Viktor Urumov (Partenij Zografski 46, Skopje, Macedonia)

Physics Education, History and Philosophy of Physics

64 Analyzing Trends in High School Physics and Mathematics Competitions in Macedonia: A Data Driven Perspective

The study presents a comprehensive data-driven analysis of student participation in national high school physics and mathematics competitions in Macedonia over the recent years. According to official datasets collected, we examine participation rates, performance trends, gender distribution, and international achievements. The analysis highlights significant patterns, including regional disparities, variations in engagement and overlapping across disciplines. A comparative perspective between physics and mathematics competitions is employed to identify common challenges and discipline-specific dynamics. The findings provide valuable insights for educators, policymakers, and competition organizing societies seeking to improve competition structures, talent identification processes, and current educational strategies. The paper identifies areas for improvement recommendations for enhancing outreach and support strategies to nurture gifted students in physics and mathematics.

Speaker: Prof. Lambe Barandovski (Institute of physics, Faculty of natural sciences and mathematics - Skopje, Ss. Cyril and Methodius University in Skopje)

65 A Simple Experimental Setup for the Demonstration of Fresnel–Arago Laws and the Realization of a Laboratory Exercise

The primary goal of this work was to create an experimental setup for an easily feasible demonstration of Fresnel–Arago laws and the realization of a laboratory exercise using red and green laser light. Modern theoretical explanations of the interference of polarized light use complex mathematical apparatus for their derivation, with which many students are not acquainted. On the other hand, the formulations of Fresnel-Arago laws, which have played a basic role in elucidating the concept of polarization of light, are much more accessible for students. In our setup a birefringent calcite is used as a beam splitter, and by adding a diverging lens (commonly used for image magnification), a large image of overlapping spots is obtained at a short screen distance. Depending on the level of beams overlapping at the position where the divergent lens is placed, a different intensity distribution of the interference fringes will be obtained. The same setup also allows the reconstruction of the original Fresnel and Arago experiment with a thin metal wire (cylinder). Quick and easy construction, relatively simple processing of the interference image, without the use of expensive devices and obtaining a clear, sharp and large interference image, make this setup very suitable for realization of a demonstrations and exercise for high school, undergraduate and master’s students.

Speaker: Jelena Jovanović (University of Belgrade, Faculty of Physics)

Abstract.BPU12.docx

66 Writing as an integral part of experimental physics

The paper reports results from a project designed to investigate the difficulties that sixty-four undergraduate students experienced while learning to write lab reports after having performed lab experiments. The participants had the opportunity to design and perform experiments in their own design (without being given guidelines). At the same time, they were giving feedback in the form of written comments to peers. Peer review is seen as one of the processes of science. Sources of data included lab reports, weekly reflective journals, interviews with the participants and peer-to-peer feedback. Results suggest that physics students experienced a variety of difficulties related to writing and that feedback enhanced the quality of lab reports throughout one semester. Yet, the use of exemplars helped the participants to internalize the expected quality and provide feedback focused on the assessment criteria. Recommendations are made about instruction and assessment criteria through which lab reports are assessed.

Speaker: Olga Gkioka (Boğaziçi University, Istanbul, Turkey)

Quantum Physics, Information and Communication

67 Probing and Controlling Many-Body Quantum Dynamics and Chaos

The notions of chaos and order are central to understanding the statistical physics of many-body systems. Thermalization and the spread of quantum information in chaotic many-body dynamics is presently attracting a lot of attention across various fields, ranging from statistical physics via cold atom physics to quantum gravity. Starting from the concept of a ”quantum butterfly effect”, this includes questions of how many-body quantum interference affects equilibration, more generally non-classicality in ergodic many-particle quantum physics. Vice versa, it is long known how to harness exponential sensitivity to changes in initial conditions for control purposes in classically chaotic systems. We will generalize this concept, using chaos as a resource for steering many-body quantum dynamics. We will address the above phenomena using semiclassical methods based on interfering Feynman paths, thereby bridging the classical and quantum chaotic many-body world.

Speaker: Klaus Richter (University of Regensburg)

68 Quantum Dynamics in Multiple Quantum Dots Systems

Quantum Dynamics in Multiple Quantum Dots Systems

Tatiana Mihaescu^{1}, Aurelian Isar^{1}, and Mihai A. Macovei^{2}

{}^{1} National Institute of Physics and Nuclear Engineering, Reactorului 30, RO-077125, Măgurele-Bucharest, Romania
{}^{2} Institute of Applied Physics, Moldova State University, Chișinău, Moldova
*E-mail: mihai.macovei@ifa.usm.md

Light-matter interactions have been always considered as a promising platform for novel applications. Therefore, here, we shall report our recent results obtained in a compound sample consisting from a semiconductor double quantum dot system, non-linearly coupled with a leaking single-mode microresonator. One demonstrates that this complex non-linear system exhibits a variety of interesting effects. Particularly, we have found the relationship among the electrical current through the double quantum dot and the microwave field inside the resonator that is nonlinearly coupled to it, with a corresponding emphasizing on their critical behaviors. Additionally, it is demonstrated that the quantum correlations of the photon flux generated into the resonator mode vary from super-Poissonian to Poissonian photon statistics, leading to single-qubit lasing phenomena at microwave frequencies [1].
The second part of the presentation focuses on a dense and dipole-dipole coupled ensemble of two-level emitters interacting via their environmental thermostat. The established thermal equilibrium of ensemble's quantum dynamics is described with respect to the dipole-dipole coupling strengths. Actually, we have demonstrated the quantum nature of the spontaneously scattered light field in this process for weaker thermal baths as well as non-negligible dipole-dipole couplings compared to the emitter's transition frequency [2].

[1] T. Mihaescu, A. Isar, and M. A. Macovei, (submitted) arxiv:2501.05967 (2025).
[2] M. A. Macovei, Phys. Rev. A. 110, 023712 (2024).

Speaker: Mihai Macovei (Institute of Applied Physics)

69 Sequre quantum teleportation of a squeezed thermal state

Secure quantum teleportation is essential for reliable transfer of quantum information across distant locations. It paves the way for future quantum networks and quantum communication systems. Consideration of an input squeezed thermal state is more realistic and appropriate for many applications because of losses caused by interaction with environment. The secure teleportation is conditioned by presence of two-way steering between the two parties and fidelity of teleportation being higher than the threshold value.

In this work, we deduce using the characteristic function approach, the analytical expression for fidelity of teleportation of an input squeezed thermal state using as a resource state an initially entangled bimodal Gaussian state. The resource is a two-mode Gaussian state.State modes are put in contact with a general Gaussian environment. As an example, we investigate secure quantum teleportation when the two modes are embedded each in its own thermal bath.

We use the Markovian Kossakowski-Lindblad master equation for describing the time evolution of the open system, quantum steering and quantum fidelity of teleportation. The studies are implemented in the framework of the theory of open systems based on completely positive quantum dynamical semigroups.

Moreover, we study the dependence of fidelity of teleportation and steering on time, bath parameters, and resource state properties. In most cases, the success of teleportation is defined by the steering presence during the experiment, because the fidelity is greater than the threshold value when the steering disappears.

Speaker: Marina Cuzminschi (Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH))

70 Optical control of single-mode phonons via artificial atoms

There is a plethora of mechanisms in quantum optics that allow for the optical control of the atomic decay. In this way, the spontaneous emission responsible for the population decay of the excited atom, can be enhanced or slowed-down. These control mechanisms can be, as well, applied to hybrid optomechanical devices that contain an emitter such as an artificial atom or a molecule. For such devices, changes in the spontaneous emission dynamics of the emitter influences the phonon dynamics as well. Here, we present how phonon dynamics behaves when optically manipulating the atomic spontaneous emission within an emitter based optomechanical device.

Speaker: Dr Victor Ceban (Institute of Applied Physics, Moldova State University)

71 Dynamics of strongly coupled harmonic oscillators in Gaussian noisy channels

We investigate the Markovian evolution of Gaussian entanglement and steering in a system consisting
of two strongly coupled harmonic oscillators immersed in a structured environment. Specically, we analyze
the contribution of the interaction between modes when the magnitude of the intermode coupling strength
is comparable to the local frequencies of the modes, and the rotating wave approximation does not apply.
Previously, the intermode strong coupling was considered in the case of a common thermal bath [1],
and presently we extend this investigation to a generalized Gaussian channel, when the environment is
modeled by a collection of squeezed bosonic modes. We also provide an extended comparison of the
evolution of entanglement and steering in weak and strong coupling regimes [2].

Speaker: Tatiana Mihaescu

72 Environment-assisted generation of quantum correlations in open quantum systems

Hellinger geometric quantum discord and interferometric power are analyzed for an open system
consisting of two bosonic modes, while interacting with four different environments: vacuum, squeezed
vacuum, thermal and squeezed thermal, taking the initial state of the open system to be either a singlemode
squeezed state, which presents no initial correlations or a squeezed vacuum state. The description
of the evolution of the correlations is formulated in the framework of the theory of open systems, based on
completely positive quantum dynamical semigroups, using the Gorini-Kossakowski-Lindblad-Sudarshan
equation. We showed that both quantum correlations can be generated from an initial factorized state
and even amplified, while also studying the back and forth impact of the squeezing parameters on the
considered correlations. For certain environments, the difference between the squeezing of the initial
state and the squeezing of the environment can either destroy the correlations or enhance them. We also
studied the presence of decoherence free states (DFS) if initial parameters are chosen suitably.

Speaker: Alina-Alexandra Stoica (1National Institute of Physics and Nuclear Engineering, Reactorului 30, RO-077125, Bucharest-Magurele, Romania)

73 Werner states in non inertial frames

We investigated the separability of a general Werner state in the framework of non-inertial frames
of references. We considered bimodal and trimodal quantum systems described by modes of different
field theories. Our analysis include the study of a free scalar quantum field for describing bosons and
a free Dirac field associated with the description of Fermions. We provided condition of separability
for both bosons and Fermions in bipartite and tripartite systems, showing that the separability of a
general Werner state is regulated by the acceleration parameters in both cases. We shown that for
bosons and Fermions the acceleration parameter decreases the logarithmic negativity between the
modes having two distinct behaviours. Bosons are supposed to undergo the entanglement sudden
death phenomena as the acceleration parameter grows, Fermions decrease but remain entangled
even in the limit of infinite acceleration. We provided graphical representation of the separability
conditions for both Fermionic and bosonic modes and we compute the purity of both cases.

Speaker: Madalin Calamanciuc (National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania, Faculty of Physics, University of Bucharest, Romania)

74 Quantum entanglement of two bosonic modes in de Sitter space

In recent years, extensive studies on quantum correlations in various scenarios, such as non-inertial
frames, curved spacetime, and an expanding universe have been performed [1–6]. In the framework
of the theory of open systems based on completely positive quantum dynamical semigroups, we
investigate the time evolution of Gaussian quantum entanglement of two bosonic modes associated
with a scalar quantum field in de Sitter space and in interaction with a thermal reservoir. We show
that quantum entanglement strongly depends on the squeezing of the bimodal state, the parameters
characterizing the thermal environment, the curvature parameter of de Sitter space, and the mass
parameter. The thermal environment and the curvature have a destructive influence on the entangle-
ment, whose survival time depends on the competition between the contrary effects provided by the
squeezing of the bimodal state, the curvature, and the thermal bath. The entanglement is minimized
for values 1/2 and 3/2 of the mass parameter, corresponding to the conformally coupled scalar field,
respectively minimally coupled massless field [7].

[1] P.M. Alsing, I. Fuentes-Schuller, R.B. Mann, T.E. Tessier, Phys. Rev. A 74, 032326 (2006).
[2] D.E. Bruschi, A. Dragan, I. Fuentes, J. Louko, Phys. Rev. D 86, 025026 (2012).
[3] G. Adesso, S. Raga, D. Girolami, Class. Quantum Grav. 29, 224002 (2012).
[4] J. Doukas, E.G. Brown, A. Dragan, R.B. Mann, Phys. Rev. A 84, 012306 (2013).
[5] B. Richter, Y. Omar Phys. Rev. A 92, 022334 (2015).
[6] M. Calamanciuc, A. Isar, Results Phys. 55, 107167 (2023).
[7] M. Calamanciuc, A. Isar, submitted for publication.

Speaker: Aurelian Isar (National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania, Faculty of Physics, University of Bucharest, Romania)

17:00 Coffee Break

EPS-TIG hands-on session “Frontier of Quantum Technologies”

Environmental and Solar Physics, Meteorology and Geophysics

75 A causal analysis between ground-level ozone and meteorological and other pollutant variables: A deep AI-based approach applied to the climate of Craiova City, Romania

Abstract:
Ground-level zone (O₃) is a key air pollutant influenced by air pollutants and meteorological conditions. Understanding the causal relationships between ground-level ozone and (i) meteorological factors and (ii) other air pollutants is critical for two reasons: 1) accurately predicting and forecasting and 2) air quality management. This research investigates the causality and time-lagged effects of air pollutants and meteorological factors on ozone formation and depletion using Granger causality tests, cross-correlation analysis, multiple linear regression (MLR), deep NARMAX model, and structural equation modelling (SEM). A time-series dataset containing hourly meteorological and ozone concentration data over multiple years is analysed to determine key drivers of ozone fluctuations. The dataset was downloaded from the Romanian Environmental Agency’s website (https://calitateaer.ro/) from four air quality monitoring stations from Dolj County. It spans five years (January 1, 2020 – December 31, 2024). The results provide insights into the delayed effects of air pollutants and meteorological conditions on ozone pollution and help develop more effective predictive models for air quality management.
Keywords: ground-level ozone, causal analysis, meteorological variables, time-series analysis, Granger causality, cross-correlation, structural equation modelling, air pollution, forecasting.
References:
[1] El Mghouchi Y, Udristioiu MT, Yildizhan H, Brancus M. Forecasting ground-level ozone and fine particulate matter concentrations at Craiova city using a meta-hybrid deep learning model. Urban Climate 2024;57:102099.
[2] Udristioiu MT, EL Mghouchi Y, Yildizhan H. Prediction, modelling, and forecasting of PM and AQI using hybrid machine learning. Journal of Cleaner Production 2023;421:138496.

Speaker: Dr Mihaela Tinca Udristioiu (University of Craiova, Faculty of Sciences, Department of Physics)

Abstract for paper 2.docx

76 Seasonal and diurnal variations of ozone concentration and influencing factors: an application of deep hybrid AI models in Craiova, Romania

Abstract:
The problem of seasonal and diurnal variations of ozone concentrations and their relationship with meteorological parameters is investigated for Craiova, Romania. By analysing hourly and seasonal trends, this study aims to identify peak ozone formation periods and the key environmental factors influencing their variability. The dataset comprises hourly ozone and meteorological data, enabling a comprehensive assessment of ozone pollution dynamics. The dataset spans five years (2020 – 2024) and comprises two categories of data: (i) 7 meteorological parameters and (ii) 13 air pollutants. The open-source data comes from four air quality monitoring stations located in Craiova. The dataset was downloaded from the Romanian Environmental Agency’s website (https://calitateaer.ro/). Statistical and Machine and Deep Learning techniques, including time-series decomposition, correlation analysis, regression modelling, and spectral analysis, are employed to extract meaningful insights. The findings will enhance understanding ozone formation mechanisms, aiding policymakers in designing effective air quality management strategies.
Keywords: ozone, air pollution, diurnal cycle, seasonal trends, meteorological influence, time-series analysis, feature selection, air quality assessment.
[1] El Mghouchi Y, Udristioiu MT, Yildizhan H, Brancus M. Forecasting ground-level ozone and fine particulate matter concentrations at Craiova city using a meta-hybrid deep learning model. Urban Climate 2024;57:102099.
References:
[2] Udristioiu MT, EL Mghouchi Y, Yildizhan H. Prediction, modelling, and forecasting of PM and AQI using hybrid machine learning. Journal of Cleaner Production 2023;421:138496.

Speaker: Dr Mihaela Tinca Udristioiu (University of Craiova, Faculty of Sciences, Department of Physics)

Abstract for paper 1.docx

77 Tracing Tornadoes Through Time: Enhancing Tornado Climatology in Romania with Historical Data and Modern Analysis

"How tornadoes form?" is a seemingly simple question, yet the answer is quite complex. Much remains to be discovered about tornadoes, tornadogenesis and the forecasting of tornadoes. One way of improving our current understanding about tornadoes is to develop detailed tornado climatologies. In this study, we are expanding the existing Romanian tornado database by meticulously documenting additional tornadic events found in historical sources.

Thus, we have conducted searches in recently available digital newspaper archives for tornado reports using keywords such as "tornado", "waterspout"( "tromba" in Romanian, a term also used in newspaper for tornadoes over land), "hurricane" (uragan), "cyclone" (ciclon), and "orcane" (orcan). The search yielded records dating as far back as the late nineteenth century, with the earliest events recorded in 1880. To the existing 199 tornadoes from the Romanian tornado database, we have added another 46 verified events. These 245 tornadoes reported between 1634 and 2024 were then used construct a new climatology of tornadoes in Romania (i.e., spatial, annual, monthly, hourly distribution). The evironments in which some of these tornadoes (after 1940) developed and evolved were analyzed using the ERA5 reanalysis data. Based on ERA5 data between 1940 and 2024, a series of convective indices were derived (e.g., CAPE, CIN, verical wind shear). The comprehensive analysis of tornado records spanning over three centuries and the inclusion of newly documented events significantly contribute to our understanding of tornado climatology in Romania.

This study not only enhances our knowledge of tornadic events in the region but also provides valuable insights into the environmental conditions conducive to tornado formation, thereby improving tornado forecasting and mitigation strategies.

Speaker: Ms Andreea Bărăscu (Faculty of Physics, University of Bucharest)

78 Solar Contribution To Earth's Global Warming?

Global warming is a phenomenon threatening humanity. Can we fight it? It appears that humanity has accepted as true the notion that the phenomenon is caused by the release of greenhouse gases as a consequence of human activity, and that if we stop emitting them, global warming will cease. For this purpose, the world allocates approximately $ 3 trillion annually. Are these funds being directed correctly? The answer in this article is negative – the phenomenon has a natural cosmic origin, and its consequences can be mitigated through measures different from those applied so far.
Continuous series of air temperature data with a length of tens of years are available as a result of the work of ground-based meteorological stations, mainly in Europe but also in other parts of the world. The study used data from over 800 stations worldwide. The cyclicity in the solar magnetic field with a basic 11-year cycle has been monitored regularly for at least 250 years by counting the sunspot number (SSN), which increases at the beginning of the cycle (“rise” phase), then decreases until the beginning of the next cycle. The joint analysis of the two series of data – ground temperature and SSN in the "rise" phase of the solar cycle shows that there is a high inverse correlation between them, i.e., the surface air temperature decreases during the day during the “rise” phase of the solar cycle. Such a relationship is not observed during the "fall" phase of the solar cycle. Satellite data show that this relationship is probably due to some synchronous increase in the Earth's cloud cover during the day during the "rise" phase. Increased cloud cover by 1 - 2% during the day and during the "rise" phase leads to a decrease in the electromagnetic radiation reaching and absorbed by the Earth's surface. As a result, the air temperature at the Earth's surface decreases. During the rest of the cycle, the cloud cover decreases, and the temperature returns to its normal value. This process would be stationary if the cyclicity of solar activity were constant over time. In the last 70 years, a decrease in the intensity of solar activity has been observed, in particular during the "rise" phase. SSN for the last 6 – 8 solar cycles has decreased. This decrease is associated with a decrease in cloud cover; as a result, the temperature of the ground air increases, indicating the phenomenon of global warming. The study contains observational arguments and analysis showing that if greenhouse gases in the atmosphere, released as a result of human activity, contribute to global warming, then their contribution is insignificant and the phenomenon is due to causes of cosmic origin. Arguments are presented in favor of the hypothesis that the reason for the increased cloudiness during the "rise" phase of solar activity is the increased number of condensation nuclei in the atmosphere. They owe their origin to the increased flows of energetic solar positively charged particles during this phase, reaching the Earth's atmosphere and penetrating it to the depth of cloud formation.

Speaker: Dr Nikolay Takuchev (Trakia University)

79 MAPPING INDOOR RADON CONCENTRATION IN GROUND-FLOOR ROOMS OF DWELLINGS IN ALBANIA

Abstract
Introduction
Materials and Methods
Results and Discussion
Conclusion
Reference

Speakers: Blerim Rrakaqi (ALAM MATER EUROPAEA CAMPUS REZONANCA), Prof. Gerti Xhixha (1Faculty of Natural Sciences, University of Tirana, Tirana, Albania)

MAPPING INDOOR RADON CONCENTRATION IN GROUND-FLOOR ROOMS OF DWELLINGS IN ALBANIA.docx

80 Forecasting PM₂.₅, PM₁₀ & AQI Using TCN: A UAE Case Study

Desert-dust events in the United Arab Emirates (UAE) frequently cause sharp increases in particulate matter (PM) pollution, posing significant risks to public health and aviation safety.
This study focuses on next-day forecasting of daily PM₂.₅ and PM₁₀ concentrations and their corresponding Air Quality Index (AQI) categories across Abu Dhabi Emirate.
We are using five years of air quality data (2015–2019) from ten monitoring stations operated by the Environmental Agency – Abu Dhabi (EAD) as well as meteorological inputs derived from METAR reports—including temperature, relative humidity, wind speed/direction, and atmospheric pressure—available as both daily aggregates and raw hourly data.
We compare traditional statistical models (SARIMA, linear regression) with deep learning approaches (Gated Recurrent Unit [GRU], Temporal Convolutional Network [TCN]). Additionally, we propose a two-tier AQI classification framework that considers both the most likely and second-most likely predicted classes to enhance robustness.
Results show that a multi-station TCN model, integrating hourly meteorological data and station characteristics, achieves superior performance. Specifically, it correctly identifies the PM₂.₅ AQI class in the first or second guess predictions 96% of the time, with errors greater than one class being exceedingly rare.
To our knowledge, this is the first application of TCNs for PM forecasting and AQI classification in the UAE. Our findings demonstrate the TCN model’s effectiveness, computational efficiency, and resilience in handling moderate-sized environmental datasets, providing a practical solution for air quality forecasting and public health readiness in arid environments.

Speaker: Mr georgios gousteris (Aristotle University of Thessaloniki, Department of Physics, Laboratory of Atmospheric Physics, 54124 Thessaloniki, Greece))

High Energy, Particle Physics, Gravitation and Cosmology

81 Degrees of freedom and quantization of higher derivative extensions of MCSP model

Higher derivatives extensions of MCSP model are considered. The Hamiltonian structure and the equivalence with some first class theories will be investigated, from the point of view of the Hamiltonian path integral quantization.

Speaker: Silviu-Constantin Sararu (University of Craiova)

82 A 2D gravity `facet' of a BF theory in the presence of some massless real scalar fields

The analysis of consistent interactions that can be introduced between a collection of BF models and a system of massless scalar fields, done in the context of antifield-antibracket symmetry by deformation to the solution to the classical master equation, exhibits two geometric structures related to the target manifold of the BF scalar fields: i) a Poisson one, due exclusively to BF sector and ii) a non-symmetric 2-tensor valued on the real scalar fields superspace manifold.

Speakers: Prof. Constantin Bizdadea (University of Craiova, Department of Physics), Eugen-Mihaita Cioroianu (University of Craiova, Department of Physics), Prof. Solange-Odile Saliu (University of Craiova, Department of Physics)

83 Drell–Yan Production Using a New Approach PDF2ISR in the PYTHIA Event Generator

A new approach, PDF2ISR, constructing an initial state parton shower which is fully consistent with the parton densities is applied to Drell-Yan production.
PDF2ISR is implemented inside the Pythia8 event generator and allows a full comparison with measurements.

This new approach is systematically cross checked with predictions using the same parton densities, including Transverse Momentum Dependent (TMD) parton density functions, inside the CASCADE event generator. After completing the systematic analysis using the toy model, the PDF2ISR approach will be applied to the simulation of real Drell-Yan pairs and compared with the most recent experimental measurements of Drell–Yan production cross sections as a function of the pair's transverse momentum.

Speaker: Dušan Subotić (University of Montenegro, Faculty of Mathematics and Natural Sciences)

Subotic_BPU12.pdf

84 Establishment of a National Laboratory for gaseous detectors in support of the cooperation between Albanian universities and the European project Compact Muon Solenoid (CMS) at CERN, specially for the Muon subsystem of the RPC (Resistive Plate Chambers).

The project aiming to establish the essential infrastructure needed to support the participation of the Albanian Scientific Cluster in the CMS experiment at CERN is in an advanced phase. It will provide the necessary tools and research infrastructure that will enable the CMS Albania UT-UPT Group to carry out its duties with high quality and efficiency. The laboratory will offer Albanian researchers hands-on experience with fundamental particle detection technologies for gaseous detectors, especially for the Resistive Plate Chambers (RPC), helping them build and enhance their expertise in developing both hardware and software systems in compliance with CERN's standards. In addition to supporting fundamental or applied research, this research infrastructure will play a key role in promoting further applications to advanced technologies. The laboratory will be a platform for students to conduct research for their Master’s theses and Ph.D. dissertations. This infrastructure is the following step, the first being the establishment of a computational center, in creating the rich environment that will boost high-quality scientific research in Albania, also advancing the application process for full membership at CERN.

Speaker: Enkelejd Çaça (Polytechnic University of Tirana)

A_Basic_Conference_Abstract_Booklet.pdf

85 Tensor models

Random tensor models, seen as quantum field theoretical (QFT) models, are a natural generalization in dimension higher than 2 of the celebrated random matrix models (known, amongst other, to be related to 2D quantum gravity). Moreover, it was discovered by Witten that tensor models are also related to the holographic Sachdev-Ye-Kitaev model.
I this talk I will present an overview of various old and new results on tensor models seen as QFT models.

Speaker: Adrian Tanasa

86 Thermodynamic Mapping of Italy’s Green Energy Transition: An Exergy-Based Leontief Input-Output Analysis of Sectoral Emissions and Entropy Flows

The transition to low-carbon energy systems requires analytical tools that integrate economic interdependencies with the laws of thermodynamics. This study develops a thermodynamically extended Leontief Input-Output (I-O) model, incorporating Environmentally Extended Input-Output Tables (EE-IOTs), to quantify exergy flows, emissions intensities, and entropy generation across Italy’s key economic sectors during its green energy transition.
By treating the national economy as an open thermodynamic system, we trace how energy carriers of differing exergy quality are allocated, transformed, and degraded across intersectoral production networks. Emphasis is placed on electricity, manufacturing, and construction—sectors critical to both economic output and energy throughput. Sector-specific exergy destruction and entropy generation rates are derived from transformation efficiencies, energy balances, and emissions data.
Results show that renewable electricity—particularly solar and wind—achieves the highest exergy efficiency and the lowest entropy generation per unit of output, generating positive systemic spillovers. In contrast, fossil-dependent manufacturing sectors emerge as thermodynamically irreversible nodes, with substantial exergy losses. The construction sector, while moderate in exergy terms, plays a pivotal enabling role in infrastructure deployment.
Scenario analysis indicates that aligning renewable energy investment with sectors characterized by low entropy-to-output ratios yields maximum decarbonization efficiency. By embedding thermodynamic constraints into macroeconomic modeling, this work presents a novel exergy-based framework for assessing the sustainability of national energy transitions. It advances the integration of physical energy metrics into economic policy design, enabling more physically consistent and systems-informed decarbonization strategies.

Keywords: Exergy analysis, Entropy generation, Thermodynamic economics, Leontief Input-Output model

Speaker: Ms Esmeralda Sinaj (University of Tirana)

ESMERALDA SINAJ Thermodynamic Mapping of Italy’s Green Energy Transition An Exergy-Based Leontief Input-Output Analysis of Sectoral Emissions and Entropy Flows.docx

Interdisciplinary Physics, Mathematical and Computational Methods

87 Balkan Web of Physics 2025

We present an updated analysis of scientific productivity in physics across the Balkan countries, continuing and expanding earlier studies based on bibliometric data. The current study is primarily based on data retrieved from the OpenAlex database, covering the period from 1996 to 2024, with an accent on last 20 years, from 2005 to 2024. To evaluate database consistency and coverage, OpenAlex results are compared with data from the Scimago database. Furthermore, preliminary data from the Web of Science will be presented.
For each country, we examine the total number of publications in physics and selected subfields (Astronomy, Condensed Matter, Nuclear Physics, and Particle Physics). We use normalization of the scientific productivity, using World Bank indicators, that enables a more accurate assessment of research intensity and national investment in science. We compare productivity and trends among the Balkan countries and more global worldwide trends, as well as trends in the selected subfields.
This analysis provides a broader context and helps identify long-term regional trends, disparities, and the relative position of the Balkan countries in global scientific activity.

Acknowledgments

G.S. Djordjevic, and M. Milosevic acknowledge the support by the Ministry of Science, Technological Development and Innovation of the Republic of Serbia under contract 451-03-137/2025-03/200124.

References:

1. Milan Milosevic, Goran S Djordjevic, Viktor Urumov, Balkan web of physics, AIP Conf. Proc. 2075, 180011 (2019) https://doi.org/10.1063/1.5091408

Speaker: Goran Djordjević (Faculty of Science, University of Nis)

Abstract_WoS_f.docx

88 Spectra of Optical Magnons in Bulk Iron

We present the results of the numerical studies of the spectra of optical magnons in bcc Fe at room conditions (𝑇 ≈ 298 K and 𝑃 ≈ 1 bar). Recently, we modelled spectra of phonons and magnons in bcc-iron at these conditions by dynamic structure factors (DSF) calculations and with the aid of Chamati potential [1-3]. It has been shown that use of this potential developed within the embedded-atom method gives the best agreement between our calculated in DSF procedure and experimental phonon and magnon spectra. The exchange parameter has been evaluated on the base of the calculated magnon spectra in the long wavelength limit. Then, the spectrum of optical magnons has been obtained numerically with the aid of the exchange parameter determined. We expect strong phonon-magnon interaction owing to peculiarities in their spectra. Our findings provide valuable insights for theorists, experimentalists and developers of new magnetic and phononic materials and devices.
Acknowledgment: This work was supported by the Grant No KP-06-N78/2 of 05.12.2023 from the Ministry of Education and Science of Bulgaria.

[1] Elena L. Angelova, Hassan Chamati, Dynamic Simulation of the Energy Spectrum of Phonons in the Magnetic BCC Iron, Comptes rendus de l’Academie bulgare des Sciences 75, 197 (2022).

[2] E. Angelova, H. Chamati, Dynamic simulation of the quasiparticle excitations spectra in the magnetic bcc iron, Journal of Physics: Conference Series 2436, 012011 (2023).

[3] E. Angelova, H. Chamati, Spectra of elementary excitations in bulk iron, ACS Omega (2025) (in print).

Speaker: Dr Elena Angelova (Georgi Nadjakov Institute of Solid State Physics – Bulgarian Academy of Sciences, Theoretical Department)

BPU12.docx

89 Inversion Algorithms for Boriçi – Creutz fermions

In this work we present some inversion algorithms used for minimally doubled fermions and a comparative study of them in the case of a specific class of MDF: Boriçi – Creutz fermions.
We have studied three main algorithms: Biconjugate gradient stabilized method BICGStab, the Conjugate Gradient method applied to the Normal Equations CGNE and Generalized minimal residual method GMRES, used for the inversion of the Dirac operator (BC operator in this case) and have seen how suitable are for non-hermitian operators, how fast they converge, the memory use and the preconditioning options.
The tests are performed in the cluster of the Faculty of Natural Sciences, in a 64^4 lattice for five different mass quarks.
The results show that the BICGStab algorithm converges faster than the other algorithm tested for Boriçi – Creutz fermions, has a low memory use and turns to be one of the more efficient for MDF uses. In the chiral limit each one of them, presents specific challenges, but in the overall BICGStab algorithm seems to be better than the others, making it the default solver for BC fermions.

Speaker: Rudina Osmanaj (Zeqirllari) (Faculty of Natural Sciences, University of Tirana)

Inversion Algorithms for BC fermions.docx

90 Smart Driving Assistant: Real-time Safety Distance and RPM Guidance

Abstract
This study presents the design and implementation of a novel vehicle safety system leveraging an ESP32 microcontroller and an array of environmental and motion sensors to dynamically calculate and display optimal following distances. Addressing critical factors influencing braking performance, the device integrates real-time data on vehicle speed, ambient temperature, and humidity to provide an adaptive safety margin, thereby significantly enhancing road safety. Furthermore, for vehicles equipped with manual transmissions, the system incorporates a unique feature that calculates and suggests the optimal engine revolutions per minute (RPM) for up-shifting, aiming to improve fuel efficiency and prolong engine life. This paper details the system architecture, sensor integration, algorithmic approach for distance and RPM calculations, and the practical implications for driver assistance and accident prevention. The developed prototype demonstrates a robust, cost-effective solution for enhancing driver awareness and optimizing vehicle operation under varying conditions. This project successfully integrates computational physics applied with driving assistant systems.
Keywords: Safety Distance, Braking Performance, Microcontroller, Sensors.
‬‬
Reference:
[1] Gaherwar, P., Dhuture, R., & Dhenge, A. (2024). Design and Implementation of Clusters of Microcontroller for various sensors data on real time using Embedded System. International Journal of Innovative Research in Engineering, 5(2), 99-102.
[2] Ali, F. M., & Abbas, N. H. (2024). Adaptive Cruise Control System: A Literature Survey. Journal of Engineering, 30(9), 239-272.
[3] Tavares, J. M. (2009). Dynamics of braking vehicles: from Coulomb friction to anti-lock braking systems. European journal of physics, 30(4), 697.

Speaker: Nicolae Florian (National University of Science and Technology Politehnica Bucharest, Doctoral School of Automatics and Computers, 060042, Bucharest, Romania)

Smart Driving Assistant. Real-time Safety Distance and RPM Guidance.docx

91 Traffic Modeling using Neural Networks: Convolution Neural Network - Long Short Term Memory

Abstract
This study opens new directions on Traffic Modeling using Neural Networks, their limitations and exploring existing research on the use of FNN, RNN and CNN architectures in this domain. Our proposed hybrid model leverages the strengths of both CNNs for recognizing spatial patterns and RNNs for capturing temporal dependencies in traffic data. The paper details our methodology, including data collection, network architecture design, training process, hyperparameter tuning, and performance evaluation. We compare our results with traditional methods and discuss their implications for intelligent transportation systems (ITS) and urban planning.
Keywords: Safety Distance, Braking Performance, Microcontroller, Sensors.
‬‬
Reference:
[1] Ferriol-Galmés, M., Paillisse, J., Suárez-Varela, J., Rusek, K., Xiao, S., Shi, X., ... & Cabellos-Aparicio, A. (2023). RouteNet-Fermi: Network modeling with graph neural networks. IEEE/ACM transactions on networking, 31(6), 3080-3095.
[2] Chan, R. K. C., Lim, J. M. Y., & Parthiban, R. (2021). A neural network approach for traffic prediction and routing with missing data imputation for intelligent transportation system. Expert Systems With Applications, 171, 114573.
[3] Abdullah, S. M., Periyasamy, M., Kamaludeen, N. A., Towfek, S. K., Marappan, R., Kidambi Raju, S., Alharbi, A. H., & Khafaga, D. S. (2023). Optimizing Traffic Flow in Smart Cities: Soft GRU-Based Recurrent Neural Networks for Enhanced Congestion Prediction Using Deep Learning. Sustainability, 15(7), 5949.

Speaker: Nicolae Florian (National University of Science and Technology Politehnica Bucharest, Doctoral School of Automatics and Computers, 060042, Bucharest, Romania)

Traffic Modeling using Neural Networks_CNN - LSTM.docx

Plasma, Statistical and Nonlinear Physics

92 The direct and inverse Lie symmetry techniques for nonlinear physical systems

The paper presents both monographic aspects and new results on how a given nonlinear differential equation can be generalized to an equation with stronger nonlinearities but with an imposed class of solutions. More precisely we are considering a general form of 2D reaction-diffusion equation and, by imposing a pre-defined class of symmetry, we are obtaining the most general equations from the considered class that accept the imposed symmetry.

The procedure is based on the Lie symmetry method and it allows us to obtain the conditions in which a given model accepts nontrivial symmetries. On the other hand, we can to identify and to solve equations that generalize well known solvable nonlinear models.

How the procedure is functioning is illustrated on the model with a mixed second order spatial derivative and with general source term, respectively on the transfer equation with power law nonlinearities.

Speaker: Alina Pauna (University of Craiova)

93 Solutions of the fractional Chafee-Infante equation by various analytical methods

The paper proposes an exhaustive investigation of how different analytical methods can be applied to solve nonlinear fractional differential equations. The considered dynamical system is described by the Chafee-Infante fractional equation. We will review the approaches that have been used previously, with a focus on two general approaches introduced quite recently by our group. One of them is known as the attached flow method, while the second is based on the so-called "optimal choice" that does not impose an a priori choice of the form of the solutions nor of the auxiliary equation.

Speaker: Dr Alina-Maria Pauna (University of Craiova)

94 Edge-core interaction via vorticity filaments emerging from ion inertial dynamics in tokamak plasma

The regime of the tokamak plasma that is relevant for the achievement of thermonuclear fusion strongy exhibits interplay between turbulence and structures. The complexity of the relation between edge and the core regions is underlined by the turbulence inward spreading from the region near the Last Closed Magnetic Surface. It has been observed that structures consisting of pairs of blobs and voids (in density) arise at relaxation of gradients, with the voids propagating toward the core and being absorbed after emission of Cherenkov-like (drift waves) radiation. The generation and the displacement of the two perturbations (blobs and voids) is not fully understood but it is considered as related to the vectorial nonlinearity, i.e. a regime described by Hasegawa-Wakatani equation.
We propose a model in which the random plumes (as in Rayleigh Benard convection) are the source of the formation of the Larichev-Reznik dipolar solution of the Hasegawa-Mima equation, which is known as resulting from the ion inertial dynamics. Either including the density (i.e. Hasegawa Wakatani eq.) or using Ertel's theorem, we connect the vorticity with the density perturbations (blob-void). Next we discuss the separation into monopolar vortices that move in opposite direction on the background of the gradient of vorticity (sheared velocity). The processes that are involved are: clusterization of like-sign vorticity and tendency to self-organization of the vorticity field. The turbulence-induced dissipation of the vorticity can sustain plasma rotation, in particular Zonal Flow

Speaker: Florin Spineanu

95 Coherence and memory in turbulence

The evolution of turbulence in magnetically confined plasmas is a complex problem that is not completely understood in spite of a huge amount of work. Low-frequency drift type turbulence, which has a significant influence on fusion plasma confinement, is analyzed here with the aim of understanding the memory effects on turbulence evolution.
We present a theoretical study based on a statistical Lagrangian approach. Essentially, the growth rates of test modes are determined as functions of the statistics of ion trajectories. The original contribution in this method consists of the deep statistical analysis of the ions, which relies on conditioned averages (on subensembles of trajectories) and reveals the coherence of their motion. Coherent (average) displacements and velocities are found in each subensemble, but they are hidden in the sense that their contributions compensate on the whole space of trajectories. However, the dispersion of the trajectories and the transport are essentially determined by these coherent elements. We have shown that a slow time variation of the potential has not the expected effect of attenuation of the coherent components. A surprising enhancement of coherence appears, associated to long-time memory of the Lagrangian potential. The memory time is much longer than the correlation time of the turbulence. As a consequence, the growth rates and the frequencies of the test modes are intrinsically time-dependent. They determine oscillatory behavior of the amplitude of turbulence with the characteristic memory time. Such evolution is in agreement with the results of numerical simulations and experimental measurement.
In conclusion, the main finding of this work is the explanation of the small frequency oscillations of drift turbulence amplitude as the effect of the memory associated to the coherent components of the ion motion.

Speaker: Madalina Vlad

Physics Education, History and Philosophy of Physics

96 Role of microcontrollers in teaching physics

Abstract: Technical and technological innovations are increasingly finding their application in modern education, making it more attractive and economically accessible. Namely, especially in nuclear physics, instruments can be extremely expensive and very sensitive, which makes it significantly difficult for schools to use them [1]. Also, schools cannot own radioactive sources, which is an additional aggravating circumstance for conducting nuclear physics experiments in schools. As physics is based on empirical tests of theoretical laws, experiments occupy a crucial place in the teaching of physics. In order to bridge the gap between the theoretical study of abstract concepts caused by the lack of equipment, which is especially present in nuclear physics, and the application of those concepts in the real world, microcontrollers have begun to be used in the teaching process. Microcontrollers with appropriate sensors can replace very expensive and sophisticated instruments, while fully displaying the corresponding physical phenomenon or process. Thus, in paper [2], an example of how students can get acquainted with gamma spectroscopy in an inexpensive way is given. Depending on the student's ability and the complexity of the laboratory exercise, the application of microcontrollers in teaching, as a student-centered approach, can promote the development of critical thinking in students, creativity and fostering problem-solving skills. In this way, through the interdisciplinary approach provided by microcontrollers, the student develops higher levels of thinking and prepares more thoroughly for future technological challenges. Also, as a student-centered approach, the use of microcontrollers can create an environment for the fuller development of potentially gifted students [3], who are often neglected in heterogeneous classrooms. Therefore, by placing the student in the active role of researcher, microcontrollers are an important tool for teaching physics.
Key words: microcontrollers, physics teaching, teaching nuclear physics.
Acknowledge
The paper was created within the framework of the Development of interactive multimedia educational and outreach projects for supporting the development of JINR-Republic Serbia collaboration. The authors gratefully acknowledge the financial support of the Ministry of Science, Technological Development and Innovation of the Republic of Serbia (Grants No. ‪451-03-137/2025-03/ 200125 & 451-03-136/2025-03/ 200125). ‬‬
Reference:
[1] Krmar, M., Šiđanin, P., Arsenić, I., Jovanović, N., Panebrattsev, Y., Klygina, K., Semchukov, P., Kamanin, D. & Radulović, B. (2023). Problems and suggestions for teaching a higher course in nuclear physics. Romanian Reports in Physics, 75 (2), Article number 903.
[2] Arsenić, I., Krmar, M., Radulović, B., Semchukov, P., Yarygin, G., & Sidorov, N. (2024). An inexpensive way to introduce students to gamma spectroscopy. European Journal of Physics, 45(6), Article number 065801.
[3] Radulović, B., & Krstić, I. (2022). Plasma speaker as an example for work with gifted students. Romanian Reports in Physics, 74(1), Article number 901.

Speaker: Branka Radulović (University of Novi Sad, Faculty of Sciences, Department of Physics)

role of microcontroller in teaching physics_.docx

97 Using Discrepant Events to Teach the Center of Mass: A Structured Inquiry Approach with the 5E Model

A discrepant event is a demonstration or phenomenon that produces an unexpected outcome, for example, an object that appears to be rolling uphill. The purpose of this research paper is to study the effect of such phenomena on the learning process, to determine whether they can improve students’ understanding of a certain concept.

In this study, the learning subject proposed is the center of mass in Secondary Education. Using the setup provided, students are called to complete two worksheets, designed according to the 5E educational model, with each activity corresponding to one of five phases: Engage, Explore, Explain, Elaborate, and Evaluate. They are also called to answer pre- and post-tests, which aim to evaluate their understanding of the concept before and after the learning process. The entire teaching module follows the guidelines of Structured Inquiry, where students experiment on the provided setup and collect data. In the end, they are asked to make appropriate conclusions based solely on the results of their investigation.

Keywords: Inquiry, Discrepant events, 5E model, Secondary Education

Speaker: Myrto Terpsiadou (Aristotle University of Thessaloniki)

98 TEACHING MOTION CONCEPTS THROUGH TRACKER - BASED VIDEO ANALYSIS

Difficulties in understanding concepts of kinematics are widespread among students at various educational levels as documented in physics educational research. Also, students find it challenging to connect the concepts of motion with equations and graphs that describe these concepts. Such difficulties often originate from intuitive understanding, shaped by their everyday experiences, which can conflict with scientific explanations. Without appropriate instructional intervention students’ misunderstandings regarding motion concepts are likely to persist and become reinforced over time, making it increasingly difficult for students to grasp more advanced topics in physics.
This work presents a learning model that utilizes Tracker software to examine videos of the free fall and oscillatory motion experiments. By directly observing and tracking object motion, this approach helps students to develop a deeper understanding of the concepts of position, velocity, and acceleration. The method combines hands-on experiments with computer modeling, allowing students to analyze data and represent motion graphically and analytically. The accuracy of using Tracker software is evaluated through the measurement of the magnitude of gravitational acceleration. In the first method, where free fall experiment video was analyzed by Tracker, an average value of g=9.984\pm\ 0.611\ m/s^2 resulted. In the second method, analyzing the video of a simple pendulum experiment by using Tracker resulted in g=9.864\ \pm\ 0.094m/s^2. Both results are in agreement with generally accepted gravitational acceleration and support the validity of using Tracker video analysis as an effective tool for school laboratory purposes.

Keywords: Tracker, experiment, video analysis, position, velocity, acceleration, free fall, oscillations.

Speaker: Prof. Silvana Mico (University of Tirana)

BPU12_ Abstract_Mico_Silvana.docx

99 Do we need new ways of promoting/teaching astrophysics, cosmology and space sciences ?

TAB

Speaker: Dumitru Vulcanov (West University of Timisoara)

Poster Session 2

100 THE PHOTOELECTRIC PROPERTIES of Sb2Se3 THIN-FILM HETEROSTRUCTURES

Sb₂Se₃ (antimony selenide) thin films are gaining attention for their potential in thin-film solar cells due to their favorable optoelectronic properties, including a suitable bandgap (~1-1.5 eV), high absorption coefficient, and relatively low toxicity compared to other materials like CdTe and CIGS. Antimony selenide compound exhibits a unique quasi-one-dimensional structure with chains of (Sb₄Se₆)n, which can influence carrier transport. For the fabrication of ZnSe/Sb2Se3 devices, close spaced sublimation method was used. In our study a Sb2Se3 source and a substrate are separated by a 2 cm distance in a controlled atmosphere 5×10-6 Torr, and the source is maintained at a higher temperature than the substrate. The low distance between the source and substrate reduces the loss probability of mass transport during sublimation. The Sb2Se3 source materials dissociate into Sb atoms and Se2 molecules which collide several times with gas molecules and then condense on the substrate surface. This process provides direct transport of each component of the source across the space to the substrate, and in most cases, the rate of transport is diffusion-limited. Both thin films were prepared by close space sublimation method. ZnSe and Sb2Se3 thin films were consecutively deposited onto ITO-coated glass substrates. A careful balance of substrate and source temperatures defines growth rate. The structural properties of Sb2Se3 are very sensitive to substrate temperature, therefore accurate control of Tsub is of significant importance. The thickness value of the ZnSe buffer layer was varied in the interval 400-900 nm, while for Sb2Se3 is taken ~ 2 μm. The substrates, purchased from Merck (Germany), had a 200 nm-thick ITO layer with a surface resistivity of 60 Ω/sq. As ohmic contact for Sb2Se3 was used Ag.
The photovoltaic characteristics of ZnSe/Sb2Se3 thin film solar cells were investigated through the wide band gap components at the room temperature (300 K) and 100 mW/cm2 illumination. The highest efficiency of 0.96 % was achieved for ZnSe/Sb2Se3 thin film solar cells with a thicker ZnSe buffer layer. The value of the open circuit voltage (Voc) and the current density (Jsc) achieve ~ 0.32 V and 5.39 mA/cm2, respectively. The fill factor (FF) is low in general, approximately 0.34. According to the theory the fill factor is influenced by the shunt (Rsh) and the series resistance (Rs), the saturated dark current density and the diode quality factor. Ohmic shunting paths, likely caused by pinholes and grain boundaries, are represented by the shunt resistance (Rsh) of 81 Ω⋅cm². The devices are having relatively high ideality factor compared to ideal values near 1, indicating high recombination pathways in the devices due to the effects of Rs and Rsh, and recombination at the ZnSe/Sb2Se3 interface, which partly explains the low Voc and FF parameters of the devices.

Acknowledgments: This study was financially supported by the Ministry of Education and Research of the Republic of Moldova, MSU, under the subprogram “Designing Supramolecular Architectures Based on Metal Phthalocyanine Derivatives and Functionalized Nanoparticles for Medical Applications,” #011209.

Keywords: Sb2Se3, thin-film heterostructures, close-spaced sublimation method.

Speaker: Ivan Gadiac (Laboratory of Organic/Inorganic Material for Optoelectronics, Moldova State University, 60, A. Mateevici str., 2009, Chisinau, Moldova)

101 Aerosols under heat waves: Interactions between pollution peaks and heat waves

Extreme weather events, particularly heatwaves, are becoming more frequent and intense in urban environments due to climate change. Tirana, a fast-growing metropolitan area, has experienced a notable rise in heatwave frequency and air pollution episodes in recent decades. This study analyses the relationship between elevated aerosol loads and extreme heat waves, aiming to understand the mutual interactions between these two extremes in this rapidly urbanizing city.
Using a combination of numerical model data for different pollutant concentrations, satellite products, and ERA5 reanalysis dataset, here are identified several heat wave events occurring during the last decades. Results show a strong correlation between hottest events and high aerosol loads. Synoptic-scale analysis suggests an increase of air pollution under stagnant air conditions during heat waves, contribute. Furthermore, urban heat island effects amplify and intensify both heat waves and pollution extremes, particularly in the city's central area.
The results of the close relationship between these extremes, emphasize an elevated risk to public health during co-occurring heat and pollution extremes, highlighting the need for continuous and appropriate environmental monitoring and early advertising systems, underscoring the importance of the strategies to mitigate the combined impacts of climate and pollution extremes in the major urban areas.
Keywords: aerosols, air pollution, heat waves, extreme events, correlation.

Speaker: Prof. Silvana Mico (Department of Physics, University of Tirana)

BPU12_abstract.docx

102 Assessing Climate Change Impacts on Crops and Livestock in Greece with Regional Climate Modeling: Model Setup, Evaluation and Future Projections

Climate change significantly affects primary production by imposing various types of stress on crops and livestock, increasing food safety and scarcity risks. The purpose of this work is to produce regional climate simulations for Greece, which aim to provide the necessary parameters required to calculate crop and livestock stress indices and their changes until the middle of the century, and thus provide guidance for mitigation and adaptation policies with regards to cultivation and animal husbandry. For that purpose, the Weather Research and Forecasting (WRF) model was employed to dynamically downscale global climate projections from the Coupled Model Intercomparison Project 6 (CMIP6), producing high resolution climate simulations (10 km) for Greece, under the most recent scenario framework for greenhouse gases emissions, the Shared Socio-economic Pathways (SSP). A reference simulation, covering the decade 2005-2014, has been produced as representative of the present climate and also as a basis for the evaluation of model performance. The future climate conditions have been examined by simulating the decade 2046-2055 under two different SSP Scenarios: SSP2-4.5, a middle-of-the-road scenario and SSP5-8.5, a high-end scenario which assumes little to no mitigation measures. In order to reduce biases related to the large scale forcing from individual global models, a bias-corrected global dataset, based on 18 models from CMIP6, has been used as initial-boundary conditions input for WRF. Finally, the ERA5-Land reanalysis dataset (~9 km resolution) was employed as reference for the performance evaluation of the WRF model. The model setup and preliminary results for model evaluation, crop water stress and livestock thermal stress in Greece are presented and discussed.

Speaker: Mr Giorgos Papadopoulos (Laboratory of Atmospheric Physics, School of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece)

103 Assessing the contribution of solar proxies to cloud cover, as differentiated by height and season

Even though decades of thorough studies have passed, there are still contradictions between scientists both concerning the main factors influencing cloud formation, and on cloud contribution to climate. Thus, until not long ago, it was considered that clouds have an overall cooling effect, while the results of the most recent studies show that clouds have a net positive forcing effect, contributing to global warming. Locally, cloud formation is due to a combination between the water uptake and the aerosol distribution and characteristics in the atmosphere. Also, other factors play indirect, but relevant roles on cloud formation and cloud cover, such as local meteorological parameters, ocean currents etc. Globally, the state of the terrestrial atmosphere is influenced by solar activity and galactic cosmic rays through the global electric circuit. This paper investigates the significance of the correlation between cloud cover and various solar proxies, namely: sunspot number (SSN), solar wind speed (SWS), and the associated interplanetary electric and magnetic fields (IEF, IMF). Each of this solar indicators have different mechanisms through which they influence atmospheric electricity and, thus, cloud cover. The study uses the first long-term cloud database, namely that provided by the International Satellite Cloud Climatology Project (ISCCP), since these data had sufficient time for validation. The values for the solar proxies were taken from NASA’s OMNIWeb database, as resulted from measurements with instruments onboard several spacecraft with geocentric orbits. Clouds types were individually-investigated as possibly-correlated with solar proxies, as cloud composites-computed global distribution maps. The study reveals that the cloud cover response to changes in various solar indicator depends on local conditions, also varying with season. E.g. high clouds cover exhibited anticorrelation with IEF in January on large areas, while low cloud cover was moderately positively correlated with SWS on extended regions in July.

Speaker: Simona Condurache-Bota (1Dunarea de Jos University of Galati, Faculty of Sciences and Environment; 2Dunarea de Jos University REXDAN research infrastructure, Galati, Romania)

Abstract_BPU_2025_Condurache_Voiculescu.pdf

104 Assessment of the urban heat island in the city of Galati

This article evaluates the urban heat island in the city of Galati, in Southeastern Romania, for the months of March and April 2023. Temperature measurements were taken every day in 10 points: five points in the city of Galati and five in the periurban and rural areas. The layout of the 10 points covered the north-south transect, between Galati and Braila, the neighboring city. Other parameters were also measured, such as humidity, pressure, heat index, wind speed, Dew point. Regarding the measured temperature, it was observed that in April there was a more balanced temperature distribution, with values around the average. March showed greater variability, with more frequent thermal extremes. Strong positive correlations were obtained between temperature and the heat index, and between temperature and Dew point. The relative humidity varied inversely with temperature, the coefficient of variation being -0.54. For wind, no consistent relationship was established with the other parameters, possibly due to the fact that it depends more significantly on several local factors (topography, buildings etc.). The t-test for Independent Samples revealed significant differences between point 4 and the other points (p < 0.05), indicating a consistent heat island effect. The Tukey HSD test was applied to identify which stations differ significantly from each other in terms of temperature. Thus, differences appeared between points, some quite large (>8 °C). The study revealed a clear north–south and west–east temperature gradient, with the city's urban center being the thermal core. Water and vegetation determined local temperature drops.

Speaker: Ms Romana Drasovean (“Dunǎrea de Jos” University of Galaţi)

abstract_BPU_2025_Drasovean_et_al_1.docx

105 Broad-Line Pulsed Powerful Laser Diodes of NIR Band for Compact DIAL Scheme

A new type of differential absorption lidar is developed that utilizes the properties of multi-chip-stack pulsed, broadband laser diode of microjoule energetic range. The laser wavelengths are tuned on/off a monitored integral resonance molecular absorption spectrum in the selected near-infrared band. The method is based on comprehensive theoretical analysis of molecular absorption implementing correlation spectroscopy and HITRAN high-resolution spectral database for remote sensing of atmospheric methane.

Acknowledgements
This research was supported by the Ministry of Education and Science of Bulgaria (support for ACTRIS BG, part of the Bulgarian National Roadmap for Research Infrastructure)

Speaker: Dr Stoyan Penchev (Emil Djakov Institute of Electronics Bulgarian Academy of Sciences)

CH4_DIAL_Pencheva_Penchev_Dreischuh_supplement.mp4

S04-107_Pencheva_Penchev_Dreischuh.pdf

106 Carbon Bricks

Energy is very important due to the fact that the need for its exploitation has increased in recent decades. The utilization of various energy resources and the focus on environmentally friendly energy sources represents a major interest in today's world. In this material, we will demonstrate how biomass and other waste can be used to produce carbon bricks for use as an energy source in Albania. We will present concrete results of carbon brick production, relying on biomass and other waste, by presenting their energy characteristics. The production of carbon bricks goes through several processes until the final product is obtained and utilized as an energy source. The use of carbon bricks, in addition to being used as an energy source, also contributes to environmental preservation by dealing with various agricultural and other waste. The production of these bricks in this study is based on the use of a simple technology, taking advantage of the raw material opportunities offered by our country, which would be of interest for energy exploitation. Carbon bricks can be produced in various sizes, offering different amounts of energy in KJ during their combustion and use as an energy source.

Speaker: Mr Taulant Taragjini (Elbasan Cement Factory)

Carbon bricks.docx

107 Comparative Stress Field Analysis in the Durrës Region, Albania: Ambient Tectonic Stress versus the November 26, 2019 Mw 6.3 Seismic Sequence

We present a comparative stress field analysis in the Durrës region of Albania based on three datasets: (i) two regional focal mechanism datasets (dr_planA and dr_planB) inverted using GISOLA and StressInverse v1.1.3, and (ii) moment tensor solutions from the November 26, 2019 Mw 6.3 Durrës earthquake sequence provided by the National Observatory of Athens. For each dataset, we estimate the principal stress orientations (σ₁, σ₂, σ₃), shape ratio φ, and friction coefficient μ. The regional field shows a stable NW–SE compressional regime with high friction (μ ≈ 0.95) and moderate differential stress (φ ≈ 0.75). In contrast, the 2019 seismic sequence displays increased differential stress (φ ≈ 0.55) and lower friction (μ ≈ 0.45), consistent with coseismic weakening and transient stress redistribution. Additionally, a stress analysis for the Mw 6.3 mainshock using the TENSOR program confirms a dominant reverse faulting mechanism with NW–SE compression. Our results reveal both the persistence of the Adriatic–Albanide compressive regime and the significant perturbation induced by the Mw 6.3 rupture, providing insights into earthquake mechanics and stress evolution in active collision zones.

Speaker: Edmond DUSHI (Department of Seismology, Institute of Geosciences, Polytechnic University of Tirana)

BPU_S04_P159_S2_DushiE_IGEO.pdf

Stress_Field_Durres_BPU12_2025_Dushi_Poster.pdf

108 CORRELATION BETWEEN TEN-DAY AIR AND SOIL TEMPERATURE VALUES DURING THE SPRING SEASON IN THE AGRICULTURAL REGIONS OF SOUTHEASTERN BULGARIA

Keywords: Southeastern Bulgaria; air and soil temperatures; correlation analysis, ten-day data; soil temperature forecast
Air and soil temperatures are of paramount importance for both the growth and development of agricultural crops, as well as for organizing some basic ago-technical activities. Any change in air temperature leads to such a change in the soil surface and the layers for sowing and planting of most spring and winter crops. Average in situ ground measurements were used for each day, and ten-day average values were calculated for multi-year periods (1992-2015 and 1986-2015). Pearson coefficients and regression equations for the spring season between air temperature and sowing soil layers have been established for each agricultural region. The results show a strong positive correlation (r > 0.90) between air and soil temperature in all layers (5, 10, 20 cm). The established regression models will contribute to a better understanding of the timing of the initial stages of plant development, while at the same time being of good practical application in choosing the optimal sowing and planting time for spring and cereal crops. In addition, a method for indirect prediction of soil temperature in shallow layers during each ten-day period of the spring months has been proposed.

Speaker: Nadezhda Shopova (Climate, Atmosphere and Water Research Institute at Bulgarian Academy of Sciences (CAWRI-BAS))

109 Determination of Radon Gas Activity Level in Unpacked Drinking Water from Different Locations in Albania

Abstract
In many countries, groundwater is the primary source of drinking water. As these waters remain in constant contact with rocks, the presence of high uranium concentrations can lead to the release of radon gas, which then dissolves into the water. While radon exposure through inhalation poses a greater risk than ingestion, raising awareness among national authorities and the public about the potential health hazards of radon in drinking water is crucial. According to Decision No. 957 of the Council of Ministers, dated December 2, 2015, the regulation "On the Guideline Levels of Radon Concentration in Indoor Environments and Radionuclide Concentrations in Consumer Goods" sets a reference level of 100 Bq/L for radon concentration in water intended for public consumption (Article 6, Point 2). However, Albania currently lacks a systematic monitoring plan for radon levels in water samples.
This study aims to determine the activity levels of radon gas in unpackaged drinking water, one of the most consumed water sources in Albania. Water samples from various natural sources across different regions of the country were analysed, with each sample undergoing two parallel measurements. The results indicate that the radon concentration levels in all unpackaged drinking water samples remained within the reference limit of 100 Bq/L.

Keywords: radon gas, drinking water, Rn-222, unpackaged drinking water

Speaker: Mrs Luljeta Disha

B.Daci-BPU 12 abstract radon.odt

110 Exploring Galaxy Mass Profiles in Strongly Lensed Quasars Observed by the Roman Space Telescope

Strong gravitational lensing of quasars is a powerful technique for probing cosmological parameters, tracing galaxy evolution, and investigating the internal structure of quasars. In this work, we explore the galaxy mass profile in lensed quasars expected to be detected by the Roman Space Telescope. Relying on estimates from previous studies, it is expected that approximately one in every 180 observed quasars will be strongly lensed by foreground galaxies, with about 85% of these events involving a single lensing galaxy. To simulate such systems, we employ Monte Carlo techniques, generating quasar–galaxy pairs based on observed redshift distributions, galaxy stellar masses, and the empirical relation between stellar mass and velocity dispersion. We model the lensing using three mass density profiles: the Singular Isothermal Sphere (SIS), Non-Singular Isothermal Sphere (NIS), and Singular Isothermal Ellipsoid (SIE). For each configuration, we compute the resulting image geometries, time delays, and magnification ratios. Our results show that the SIS and NIS models yield comparable time delays, typically ranging from a few hours to several years. In contrast, the SIE model—accounting for galactic ellipticity—produces a broader range of time delays, double-image configurations generally exhibiting longer delays. We also compute the magnification for each image and calculate their magnification ratios, which span several orders of magnitude across the three models. Notably, the largest magnification contrasts occur in double quasar systems. These findings are valuable for constraining galaxy mass distributions in lensed quasars and enhancing our understanding of large-scale cosmic structure.

Speaker: Esmeralda Guliqani (Department of Mathematics and Physics, ''Fan S. Noli'' University of Korça, Albania)

111 Factors influencing the regional climate variability of the South-Еastern Europe

This study investigates the primary factors influencing regional climate variability in South-Eastern Europe, focusing on the role of the North Atlantic Oscillation (NAO) and its internal and external drivers. The analysis considers the impacts of the lower stratospheric ozone, geomagnetic field variations, solar activity, galactic cosmic rays (GCR), and atmospheric CO2. By applying both linear and nonlinear Artificial Neural Networks (ANNs) statistical methods, the study identifies ozone and geomagnetic variability as the most influential factors shaping NAO behaviour over the last century.
The working hypothesis, considering the mechanism of the above factors on NAO variability, suggests that changes of the geomagnetic field modulate cosmic ray fluxes, which in turn affect ozone production near the tropopause. Resulting ozone variations influence atmospheric temperature and moisture structure, contributing to changes in surface pressure and indirectly affecting climate conditions in South-Eastern Europe through the NAO-related dynamics.
In addition to pressure anomalies, NAO phase shifts are accompanied by distinct changes in wind circulation over the region, influencing the transport of heat and moisture. While not part of the underlying mechanism, these wind changes reflect the broader impact of NAO variability on the regional climate.
Keywords: North Atlantic Oscillation, South-Eastern Europe, stratospheric ozone, geomagnetic field, climate variability

Speaker: Tsvetelina Velichkova (Climate, Atmosphere and Water Research Institute at Bulgarian Academy of Sciences)

Velichkova et al_Abstract_BPU 12 Congress.pdf

Velichkova et al._Poster.pdf

112 Greenhouse Gas Emissions Analysis and Forecast evaluation in the South Eastern part of Europe

Recently, greenhouse gases (GHG), which include: carbon dioxide, methane, nitrous oxide and other gases, are considered to be the fundamental cause of global climate change. This issue related to climate change has received conclusive attention at a global level. In the specialized literature, carbon dioxide has been considered the most significant gas contributing to global climate change. In this regard, our paper presents an analysis of greenhouse gas emissions in Romania, together with a prediction component for the following period. For this study, data were taken from the National Air Quality Monitoring Network in Romania, with historical data series selected for analysis. In order to structure the results, the collected data were initially analyzed using statistical investigation methods. The trends in greenhouse gas emissions (GHG) in Romania were analyzed both by ANOVA and multivariate analysis methods. In the second part, we implemented a numerical algorithm of the FIR -LRS type to build a dynamic model that allows the investigation of the dynamics with an error below 10%. The results obtained for the set of selected monitoring points showed that the numerical analysis of the FIR type of total GHG emissions in Romania had a higher forecast accuracy than the statistical analysis method. From the set of statistical and numerical methods used we can conclude that emissions are on a descending scale, and the choice of an appropriate method is important in data analysis.

Speaker: Romana Drasovean (“Dunǎrea de Jos” University of Galaţi)

abstract_BPU_2025_Drasovean_et_al_2.docx

113 Lightning Frequency over the Bulgarian Black Sea Coast

Analyses of the annual global lightning distribution show that, depending on the underlying surface, lightning frequency over continents is 1–2 orders of magnitude higher than over oceans.
However, studies in specific regions indicate that lightning frequency over water surfaces can exceed that over land, depending on orographic features, the respective season, and the diurnal cycle. This highlights the need for regional-scale studies.
In addition, each coastal zone is a unique transitional area between land and sea, characterized by its own diurnal wind circulation. Therefore, it is of particular interest to study the distribution of
lightning over the Bulgarian Black Sea coast, which is the aim of this work.
The results show that the annual lightning frequency over the Bulgarian Black Sea coast is higher than over the entire Black Sea coastline and the Black Sea itself, but lower than over the land territory of Bulgaria.
According to the seasonal distribution of lightning frequency:
- In spring and summer, lightning activity over the coastal areas (the Bulgarian Black Sea coast and the entire Black Sea coastline) follows the annual trend—being higher than over the sea, but lower than over land.
- In autumn, lightning is most frequent along the entire Black Sea coastline, with activity over the Black Sea exceeding that over both the Bulgarian coast and the territory of Bulgaria.
The monthly lightning distribution reveals that July is characterized by the highest lightning frequency over the Bulgarian coast, while December has the lowest.

Speaker: Natalia Doktorova (Sofia University)

Abstract_Coast_KDP_BPU12_2025.pdf

114 Long-range transported Canadian biomass-burning aerosol observed over Sofia, Bulgaria

Studying biomass-burning aerosols is essential for assessing their impact on climate, air quality, and human health due to their complex interactions with atmospheric processes and radiation. Annually, huge amounts of biomass-burning aerosols are released into the atmosphere as a result of large-scale seasonal wildfires, particularly in regions of the United States and Canada. These aerosols are frequently subjected to long-range atmospheric transport, often reaching Europe. The 2023 wildfire season in Canada was the most extensive and prolonged on record, with exceptionally high emissions of biomass-burning particles from mid-April to late October. These emissions considerably deteriorated the air quality both locally and across large portions of the Northern Hemisphere.
In this work, we present results of a multi-sensor study of long-range-transported smoke aerosols originating from Canadian wildfires observed over Sofia, Bulgaria, in October 2023. The measurements were conducted at the Sofia aerosol remote sensing station (42.653N, 23.387E, 610 m ASL) located within the Institute of Electronics at the Bulgarian Academy of Sciences (IE – BAS) in the southeastern part of the city. The station is contributing to several international networks, including the European Aerosol Research LIdar NETwork (EARLINET), the AErosol RObotic NETwork (AERONET), the program E-Profile, and the Pan-European research infrastructure ACTRIS (The Aerosol, Clouds and Trace Gases Research Infrastructure). A comprehensive set of ground-based remote sensing instruments (lidar, ceilometer, and sun photometer) was employed in the investigations, supported by model, forecast, satellite and meteorological data. The source and type of the detected aerosols are confirmed through air mass backward trajectory analysis and global satellite-based fire maps. The optical and microphysical characteristics of the registered aerosol layers, such as the backscatter coefficients, backscatter-related Ångström exponents (BAE) and volume linear depolarization ratio were vertically profiled with a high range resolution by lidar. The registered high BAE values of the order of 1.5–2 indicate a dominance of fine, submicron particles in the smoke layers. In support of the lidar data, the sun-photometer-provided columnar optical and microphysical characteristics show that the contribution of the fine-mode aerosols to the total aerosol optical depth is more significant than that of the coarse-mode particles. The low depolarization ratios observed by both lidar and photometer indicate that the smoke particles were mostly spherical. Additionally, the experimental data revealed coarse-aerosol presence within the local planetary boundary layer, likely associated with regional continental sources. The results presented contribute to a deeper understanding of the dynamics and impacts of long-range biomass-burning aerosol transport in the context of European air quality and atmospheric composition.
This work was supported by the Ministry of Education and Science of Bulgaria (support for ACTRIS BG, part of the National Roadmap for Research Infrastructure) and by the European Commission under the Horizon 2020 – Research and Innovation Framework Program, Grant Agreement No. 871115 (ACTRIS IMP).

Speaker: Tanja Dreischuh (Institute of Electronics, Bulgarian Academy of Sciences)

115 Recent HERA Standard Model results

Although the HERA experiments finished data collection more than 15 years ago, there is still a lively program ongoing within the H1 Collaboration, with maximum effort put into learning as much as possible from the deep inelastic scattering experiments. This report presents the most recent measurements of Standard Model physics from the H1 experiment, emphasizing new techniques based on deep learning applied to obtain these measurements.

Speaker: Nataša Raičević (University of Montenegro)

116 Solar-induced stratospheric circulation changes

The incoming solar radiation and heating depend on the solar activity (SA), which undergoes cyclic changes with a period of about 11 years. Variability in solar ultraviolet (UV) radiation influences stratospheric dynamics through photochemical and radiative processes. Changes in the SA can affect the temperature and circulation, changing the conditions for the propagation and reflection of planetary waves (PW) and gravity waves (GW) in the upper atmosphere. This paper explores the mechanisms by which solar-induced changes in UV flux alter the temperature structure and circulation of the stratosphere, focusing on the Brewer-Dobson circulation, zonal wind variability, and their tropospheric coupling. Using both observational data and model results, we discuss how changes in solar activity affect climate variability.

Speaker: Prof. Gordana Jovanovic (Faculty of Science and Mathematics, University of Montenegro)

117 Systematic Analysis of Multi-Planet Systems: The EXO-RESTART Project

The EXO-Restart project at Sofia University aims to detect and dynamically characterize multi-planetary systems using various methods, including transit, radial velocities (RVs), and transit timing variations (TTVs). Studying the dynamical architecture of multiple-planet systems is vital since it reveals information about their formation mechanism and evolution. To gain deeper insights into planet formation, we focus on the dynamical properties of these systems, particularly retrieving the osculating orbital parameters using N-body models, as opposed to relying solely on the Keplerian best-fit parameters reported in the literature. We developed the "Exo-Striker" toolbox as a powerful and efficient Python library designed for exoplanet orbital analysis and N-body simulations for our needs. In our project, we combine original exoplanetary data from spectroscopic facilities like HARPS, HIRES, and CARMENES, which include more than 5000 unique stars, as well as the TESS transit photometry survey data. Finally, our work includes extensive long-term stability and dynamical analysis to ensure accurate modeling and predictions of planetary system behavior.

Speaker: Elena Vchkova Bebekovska (Institute of Physics, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius, University in Skopje, Macedonia)

118 Tentative Spatio-Temporal Correlation Between Indoor Radon Concentration Variations and Moderate Earthquakes in Albania: A Case-Based Statistical Approach

This study investigates the potential correlation between long-term indoor radon concentration changes and moderate seismicity (Mw ≥ 4.0) in Albania. Radon measurements conducted during three independent campaigns (1999–2000, 2014, and 2022) were analyzed at repeated sites to assess temporal variations, and were matched with seismic events within a 50 km radius and within a 0.2-year temporal window. Among 50 repeated radon measurement points, only one site (Zall Bastar, NE of Tirana) demonstrated a compelling spatio-temporal correlation with a local earthquake (Mw 3.7, June 2022). This case suggests that, under specific conditions of dense spatial coverage and improved temporal resolution, radon anomalies may offer valuable insights into crustal stress variations. However, the overall weak correlation across the dataset highlights the limitations of campaign-based measurements and reinforces the need for continuous monitoring in active tectonic zones. The findings support the integration of geochemical and seismological observations to enhance earthquake hazard assessments in Albania.

Speaker: Irena Dushi (Department of Seismology, Institute of Geosciences, Polytechnic University of Tirana, Albania)

Poster_Po97_DushiIrena_IGEO-1.pdf

Radon_Earthquakes_Rumania2025_DushiIrena.pdf

119 The spatiotemporal distribution and polymer composition of microplastics in the Ishmi River in Albania

Abstract
In recent years, research on microplastics in rivers has undergone rapid expansion, resulting in the revelation of widespread contamination and the subsequent emergence of concerns regarding ecological and human health impacts. A multitude of studies have confirmed the presence of microplastics in European rivers, with microplastic density demonstrating seasonal variations. The reported concentrations of microplastic in surface waters vary considerably, ranging from as low as 0.03 particles per cubic meter up to extreme values of nearly 187,000 particles/m³. The presence of microplastic pollution in Albania's freshwater systems represents a novel and growing concern. Albania has not yet established a comprehensive river estuary cleaning system, incorporating automated stations or permanent structures. Current initiatives are predominantly pilot investments from voluntary and non-governmental organizations. The objective of this study is to investigate the spatiotemporal distribution and polymer composition of microplastics in the Ishmi River, which drains the Tirana-Fushe Kruja region with a delta into the Adriatic Sea.
Surface water samples were collected at six stations along the Ishmi River in a two-time sampling calendar, September 2024 and March 2025. It is noteworthy that microplastic levels exhibited an increase at four of the six stations between 2024 and 2025, with the highest concentration (~4 particles/m³) being recorded at a mid-river station situated in proximity to urban areas in 2025. Polymer analysis revealed a diverse mix of plastics; polyethylene, polystyrene and polypropylene fragments, film and synthetic fibers were commonly identified. These results indicate that microplastic pollution in Ishmi River is significant and appears to have worsened over time, likely driven by urban runoff and inadequate waste management. The findings emphasize the necessity for ongoing monitoring of Albanian rivers and the implementation of mitigation measures, such as enhanced waste management and wastewater treatment, to minimize plastic inputs. A comprehensive reduction in land-based plastic pollution will contribute to the preservation of riverine and coastal ecosystems downstream.

Key words: microplastics, spatiotemporal distribution, polymer, river water, waste management.

Speaker: Alda Osmeni (European University of Tirana)

Alda Osmeni Bpu12.pdf

120 The velocity in static spherical metric of f(R) quadratic langrangian gravity

Nenad Dj. Lazarov
Department of Theoretical Physics and Condensed Matter Physics (020), Institute of Nuclear Sciences Vinča-National Institute of the Republic of Serbia, University of Belgrade, P.O. Box 522, 11001 Belgrade, Serbia.

Email:lazarov@vinca.rs

ORCID ID Nenad Dj. Lazarov is: 0000-0003-3173-9636

Abstract. This paper will consider the behavior of the velocity obtained from the static spherically symmetric metric resulting from the square langragian of f(R) gravity. Metric is given by E. Pachlaner and R. Sexl in their paper [1]. Also It will be shown the expressions for radial and total velocity of cosmos in one and two space dimensions and to discuss their behavior. The metric obtained from the langragian which is different from Einstein’s by the square term of the Ricci scalar. The exact equations of fields are too complicated to be solved, it solved in weak field approximation.

[1] E. Pachlaner and R. Sexl: On quadratic langragians in general relativity. Communication mathematics physics 2 (1966), pp. 165-175.

Speaker: Dr Nenad Lazarov (Institute of Nuclear Sciences Vinca, University of Belgrade,)

abstract BPU12 Nenad Dj. Lazarov S05.doc

The velocity in static spherical metric of f(R) quadratic langrangian gravity A0 format Nenad Lazarov.pdf

121 Visual Modeling of Radon Concentrations in Muğla Province (Southwestern Turkey)

Radon (²²²Rn) is a carcinogenic, inert noble gas that is undetectable indoors by human senses due to its odorless, colorless, tasteless, and silent nature.
This study aims to (1) measure the Indoor Radon Concentration (IRC) in 840 Mosque-Minarets (MMs) across Muğla Province (13 districts) in Southwestern Turkey, (2) examine the relationship between IRC and Soil Radon Concentration (SRC) in relation to underlying geological formations, building materials, and active faults, and (3) compare IRC values with the European Indoor Radon Reference Value (EIRRV) of 200 Bq/m³ to identify high-risk areas (> 200 Bq/m³) for human health, particularly lung cancer.
IRC measurements were conducted using the RadonEye device, while SRC measurements were taken with the Markus 10 device, both employing the active method. These measurements were carried out in Muğla Province between 2018 and 2020. The results, along with geological formations and active fault data, were visualized and analyzed using the ArcGIS program.
The highest IRC (2809 Bq/m³) was recorded in an MM in the Muğla-Marmaris district, constructed from uranium-rich volcanic rocks. In the Muğla-Bodrum district, the highest SRC (120,000 Bq/m³) was found in alluvium derived from uranium-rich volcanic rocks near active faults. Conversely, the lowest SRC (1000 Bq/m³) was detected in the Muğla-Datça district, in alluvium originating from partially serpentinized peridotite.
Analysis revealed that 10% of MMs in Muğla Province exceeded 200 Bq/m³, 30% exceeded 300 Bq/m³, and 40% exceeded 400 Bq/m³. The study emphasizes the need for regular and systematic IRC measurements in buildings worldwide, with relevant institutions ensuring levels remain below 200 Bq/m³. If IRC exceeds this threshold, immediate mitigation measures should be implemented to reduce radon exposure and associated health risks.

Speaker: Türkan Alkan (İzmir University of Economics)

BPU-Visual Modeling of Radon Concentrations in Muğla Province.docx

122 Public effective dose assessment using gross alpha and beta radioactivity levels of drinking water in Albania

The presence of radionuclides in water poses potential risk for health effects, especially when these radionuclides are deposited in human body through drinking. To assesspublic effective dose due to gross alpha and beta in water, 56 tap water samples were collected from different areas in the different cities of Albania. According to Albanian legislation, Article 6, the gross alpha/beta radioactivity concentration in water, should be below the level of 0.1 Bq/L and 1 Bq/L respectively for human consumption.
The instrumentation used to count the gross α and gross β activities was an α/β counter of the Ultra-Low Level α/β Counter, MPC 9604, Protean Instrument Corporation, multiple detector type with 4 sample. The activity concentrations vary in the interval 0.011 ± 0.002 Bq/l to 0.092 ± 0.012 Bq/l for gross α and 0.090 ± 0.009 Bq/l to 0.643 ± 0.067 Bq/l for gross β in drinking water. The public effective dose assessment showed values of dose to ingestion of alpha and beta emitter radionuclides lower then the recommended value of dose for drinking water 0.1 mSv/y. For all samples the gross β activity is always higher than the gross α activity.
Keywords: Effective dose, Gross alpha beta radioactivity, Water sample, Gas proportional counters

Speaker: Florinda Cfarku (Department of Radiometry and Radiochemistry, Institute of Applied Nuclear Physics, University of Tirana)

Florinda_Cfarku_poster_BPU_12_2025_online_final.pdf

123 RADON LEVELS IN ALEKSANDËR MOISIU UNIVERSITY CAMPUS, DURRËS (ALBANIA)

The activity concentrations of indoor radon were assessed in the three structures of the University of Aleksandër Moisiu Durrës. The measurements were conducted utilizing a passive technique that relies on CR-39 solid-state nuclear track detectors. Measurements were taken at various floor heights under typical usage scenarios during both warm and cold weather conditions. In a specific case, the active method was employed, and measurements were compared between day and night over a span of approximately two weeks. The yearly average concentrations were observed to vary between 20 and 92 Bq m-3. The average dose from exposure to indoor radon is estimated at 0.6 mSv annually. These findings suggest there is no significant radiological health risk, since the observed activity levels are far below the reference level set in the Albanian legislation for workplaces.

Speaker: merita xhixha

Poster-BPU12 MXH.pdf

Thursday 10 July

Plenary Session 3

124 Perpectives and opportunties at ELI-NP

Extreme Light Infrastructure - Nuclear Physics (ELI-NP) was implemented as part of the pan-European Extreme Light Infrastructure project with the aim to use extreme electromagnetic fields for nuclear physics studies and related topics. The physics case of ELI-NP is based on two state-of-the-art sources of extreme light: a high-power laser system and an intense gamma beam system. A broad range of research topics is being developed at ELI-NP aiming to push scientific and technological knowledge beyond nowadays frontiers. The main research field pursued at ELI-NP is nuclear photonics.
The ELI-NP high-power laser system consisting of two 10 PW ultra-short pulses laser arms represents a unique system worldwide and it is operational since 2020. The main research topics are focused on: understanding the fundaments of the laser-matter interactions, new paradigms for the acceleration of electrons and ions driven by high-power lasers, nuclear reactions in plasma of astrophysical interest, generation of brilliant neutron sources, applications in medicine and industry. Since 2022 the high-power laser system is operated as user facility at the power exits of 100 TW and 1 PW. The experimental setups dedicated to 10 PW laser power levels are in the final stage of testing their performance. An overview of the laser experimental setups and of the first results will be presented. Extreme acceleration fields as high as 100 GV/m were achieved during the first experiments. The capability of reaching unprecedented laser intensities of the order of 10 W/cm was demonstrated. A rich scientific program dedicated to the development of technologies with potential use in medical applications will be illustrated.
The intense gamma beam system, is under implementation aiming to provide quasi-monochromatic gamma beams with high spectral densities tailored for nuclear physics experiments covering a range of energies of interest up to Pygmy and Giant Dipole Resonances. A set of complex experimental devices for high resolution and high efficiency detection of gamma rays, charged particles and neutrons was developed to take advantage of the properties of the gamma beams.

Speaker: Calin Alexandru Ur (ELI-NP / IFIN-HH)

125 Testing physics beyond the standard model in the study of weak interaction processes

Weak interaction processes such us beta and double-beta decays provide a rich testing ground for physics beyond the Standard Model. In this talk, I review current investigations to obtain key insights about still unknown properties of neutrinos and possible violations of some fundamental symmetries in physics. In particular, I show how the precise calculation of phase space factors, electron spectra and their correlations and nuclear matrix elements are key ingredients for the much-needed theoretical support in beta, double-beta, and dark matter experiments.

Speaker: Sabin Stoica (CIFRA)

126 Shear-driven anomalous diffusion

Shear-driven diffusion represents a form of turbulent diffusion of a diffusing impurity in a stream with a velocity gradient. This issue has attracted much attention and has been studied for years. However, the linear shear flow in two-dimensional anomalous motion is not well studied. We study such anomalous process by introducing a memory kernel in the corresponding Fokker–Planck equation, which occurs due to the the long-tailed waiting time of the particle while performing a two-dimensional Brownian motion in a linear shear flow. Thus, the corresponding motion becomes non-Markovian. By analysis of the probability density function and the moments, we showed that the system exhibits characteristic crossover anomalous dynamics. Additionally, we introduce a stochastic resetting of the particle performing a shear-driven anomalous motion to the initial position, and we showed that the system reaches a non-equilibrium stationary state in the long time limit.

[1] T. Sandev, A. Iomin, J. Kurths, and L. Kocarev, Phys. Fluids 37, 067101 (2025).

Speaker: Trifce Sandev

bpu2025.pdf

10:30 Coffee Break

EPS-TIG hands-on session “Frontier of Quantum Technologies”

Atomic, Molecular and Optical Physics

127 A Review of Lead Contamination in Environmental Matrices

Lead, a toxic heavy metal, poses significant threats to both environmental ecosystems and human health. Its persistence in the environment, coupled with its potential for bioaccumulation, are key factors contributing to its harmful impact. Given the interrelated nature of environmental components, lead can easily infiltrate the food chain, resulting in serious health risks for both humans and animals. This study aims to assess the concentration of lead across various environmental matrices including soil (both surface and profile), water (drinking, surface, groundwater, and packaged), vegetation, and aerosols in selected urban and industrial areas of Albania. A total of 250 samples were collected and analyzed using Atomic Absorption Spectrometry (AAS), with both flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrometry (GFAAS) employed for accurate and sensitive quantification of lead. The results reveal substantial variation in lead concentrations across the analyzed environmental components. The highest concentrations were detected in surface soils, profile soils, and aerosols, particularly in regions near industrial activities such as the metallurgical complex in Elbasan, the former battery production plant in Berat, and certain locations in Tirana. These findings highlight the elevated risk of lead contaminating the food chain and pinpoint specific areas at increased environmental and public health risk. Certified reference materials (CRMs) from the International Atomic Energy Agency (IAEA), which correspond to the environmental matrices being analyzed, were used to ensure the accuracy, precision, and reliability of the analytical procedures. This study underscores the critical need for continuous environmental monitoring and provides crucial data for identifying specific urban and industrial zones in Albania at risk of lead contamination. The results support the development of evidence-based strategies for environmental management and public health protection, promoting a cleaner, healthier environment by mitigating heavy metal pollution, especially lead, which remains highly toxic even at low concentrations.

Speaker: Mirela Alushllari (Institute of Applied Nuclear Physics, University of Tirana, Tirana, Albania)

alushllarim_abstrakt_A Review of Lead Contamination in Environmental Matrices.docx

128 Using structured light for controllable splitting and coherent beam recombining of intense femtosecond beams/pulses

Ultra-short laser pulse generation, along with extreme nonlinear processes such as high-harmonic generation, are extensively studied and actively evolving areas in modern photonics. Since their discovery, researchers have been addressing challenges like spectral broadening, filamentation, pulse and beam diagnostics, pulse amplification, and coherent beam recombination.

A key application that deserves special focus is the spectral broadening of intense femtosecond pulses, essential for their subsequent temporal compression. At high intensities, beams can become unstable, a challenge that can be mitigated by controllably splitting the beam into sub-beams. However, this approach is only viable if there is a reliable method to coherently recombine the sub-beams after spectral broadening, allowing for pulse compression just before they enter the laser-matter interaction zone.
Meanwhile, singular optics is another rapidly advancing field, focused on shaping laser beams by embedding phase singularities within them. In this work we implement known objects from the area of singular optics, like optical vortex arrays in the fields of ultra-short laser pulses in attempt to solve the problem of beam splitting and their subsequent coherent recombining.

We will present our recent advances in addressing spectral broadening and temporal compression of high-energy femtosecond pulses by controllable splitting and coherent beam recombining of femtosecond beams/pulses using structured light, more precisely optical vortex lattices. This controllable and reversable beam reshaping technique known from the field of singular optics is the key feature in the presented approach. Using fused silica vortex phase plates, etched with square-shaped optical vortex lattices we achieved an experimental realization of controllable beam splitting, followed by nonlinear spectral broadening (both in ambient air and in fused silica substrate) and a final coherent beam recombination. Moreover, the compression in time (down to the Fourier transform limit) of the spectrally broadened pulses is demonstrated as well. In our view, the results confirm the feasibility of the proposed idea and provide strong motivation for further optimization and investigation serving as potential alternative to the established methods for coherent beam recombining.

We acknowledge funding of the Bulgarian National Science Fund (project KΠ-06-H78/6). The work was also supported by the Bulgarian Ministry of Education and Science as a part of National Roadmap for Research Infrastructure, project ELI ERIC BG. L.S. and A.D. were also supported by the European Union NextGenerationEU through the “National Recovery and Resilience Plan of the Republic of Bulgaria, project BG-RRP-2.004-0008-C01”. L.S. would like to gratefully acknowledge the Return Grant awarded by the Alexander von Humboldt Foundation.

Speaker: Dr Lyubomir Stoyanov (Department of Quantum electronics, Faculty of Physics, Sofia University "St. Kliment Ohridski")

129 LASER-INDUCED BREAKDOWN SPECTROSCOPY (LIBS) FOR COINS ANALYSIS

Laser-induced breakdown spectroscopy (LIBS) is a powerful and rapid optical emission spectroscopy used for the elemental analysis of a wide variety of materials. In contrast to spectroscopic methods dependent on X-rays (e.g. XRF), LIBS offers the ability for trace analysis even for light elements. The emission from microplasma created by a focused 30 fs pulse laser beam at λ=800nm, is collected and analyzed. The identification of the recorded spectral features allows the determination of the elemental composition and structural formation of the irradiated samples. Eleven coins, originating from different countries and spanning a chronological range of over one hundred years, were studied. The primary objective of the study is to demonstrate the effectiveness of LIBS as a tool for rapid qualitative elemental analysis in cultural heritage studies.
The analysis revealed that most of the coins contained copper (Cu) as the predominant element, which is consistent with common coining practices. In addition to copper, minor elements such as iron (Fe), nickel (Ni) and manganese (Mn), were detected in several samples. Trace levels of other elements, including zinc (Zn), lead (Pb), aluminum (Al) and calcium (Ca), were also observed in some coins, suggesting either intentional alloying or contamination during manufacturing. The subsequent consequences of laser ablation on the coin surfaces were also explored. For three selected coins, the diameter of the created craters was measured, providing information on the surface response.

KEYWORDS:Laser-induced breakdown spectroscopy (LIBS), coins, structural analysis, ablation

Speaker: Prof. Silvana Mico (Department of Physics, University of Tirana)

BPU12_Abstract_SilvanaMico_2.docx

130 An annual dataset of atmospheric 7Be and 210Pb measurements in air concentration

7Be and 210Pb air concentrations were measured by gamma spectrometer with a High Purity Germanium detector (HPGe). The data obtained on activity concentration for both radionuclides provide key information on the origins and movements of air masses. A routine air radioactivity monitoring has started since 2021 in a typical aerosol sampling station, ASS -500, located at the Institute of Applied Nuclear Physics in Tirana, Albania. For this paper, the activity concentration of 7Be and 210Pb in ground level air during last year, from January 2024 to December 2024, was considered. We are under working with data processing to see the variation of radionuclides during these five years. The cylinder geometry efficiency curve generated by Canberra’s Laboratory Sourceless Calibration Software (LabSOCS) was used to analyze the air filters. The obtained results show the activity concentrations of cosmogenic 7Be ranged from 1.19 to 5.95 mBq m–3 with a maximum in the summer period. The activity concentrations for 210Pb were in the range of 0.34 to 1.93 mBq m–3. The obtained results in the determination of activity concentrations are comparable with those reported by other investigators and show seasonal variation for 7Be and 210Pb.

Speaker: Prof. Manjola Shyti (University of Tirana, Institute of Applied Nuclear Physics)

BPU 12 Congress oral Presentation_M.Shyti.pdf

131 Preplasma influence on laser prepulse interaction with flat and 1D-grated targets.

Laser-driven experiments are strongly influenced by non ideal temproral profile of laser pulse. Laser main pulse is preceded by by low a long low intensity prepulse. Prepulse intensity is up to $10^{14}$ times smaller then main pulse intensity but its duration can reach 2.5 ns [1]. During the prepulse the target is heated up and preplasma appears in front of the target. Preplasma influences optical properties.

In our work we study the preplasma generation and expansion in front of grated and flat targets, and the reflectivity evolution during the prepulse-target interaction. We used radiation-hydrodynamic FLASH code to evaluate numerically the preplasma behavior. We use real temporal laser profile, to make simulation results closer to experiment. We compare the preplasma distribution in front of flat and 1D-grated targets. The preplasa in front of flat target reperestnt a thin dense layer along the targets surface. The preplasma density in front of grated target has nonuniform distribution, and is located between the grating elements and in front of the target. The analysis of preplasma evolution in time show that grated targets are heated more uniform and more efficient than the flat ones.

Moreover, we analyzed analytically and numerically the radiation absorption in preplasma-target ensemble. We deduced the reflectivity of grated targets using effective refractive index model and Bloch waves approximation. The reflectivity of grated target first decrease with preplasma generation and after increase, when the preplasma density reaches the critical value. The analytical model predictions are confirmet by numerical simulations.

• The results presented in this work were obtained during the state at Extreme Light Infrastructure (ELI-NP).
  The authors thanks J. F Ong and O. Tesileanu for useful discussions.

References:
[1] Ong, J. F., et al. "Nanowire implosion under laser amplified spontaneous emission pedestal irradiation." Scientific Reports 13.1 (2023): 20699.
[2] Fryxell, Bruce, et al. "FLASH: An Adaptive Mesh Hydrodynamics Code for Modeling Astrophysical Thermonuclear Flashes." The Astrophysical Journal Supplement Series 131.1 (2000): 273.
[3] Khan, Muhammad Umar, and Brian Corbett. "Bloch surface wave structures for high sensitivity detection and compact waveguiding." Science and technology of advanced materials 17.1 (2016): 398-409.

Speaker: Alexei Zubarev (National Institute for Plasma Laser nd Radiation Physics (INFLPR))

132 Generation of Long-Range Quasi-Non-Diffracting Bessel-Gaussian Beams in Few-Cycle Femtosecond Laser Fields

In this talk we will describe a new, simple and robust method for generating long-range Bessel-Gaussian beams with divergences on the microradian scale. The approach is entirely based on singular and Fourier optics. Initially, an optical vortex (OV) with a high topological charge (~20 and higher; [1]) is formed on the input Gaussian laser beam with a flat wavefront. Due to the modulation instability (which plays a positive role here), the vortices decay into single-charged ones. Repulsing, they transform the Gaussian beam into a ring-shaped beam with a large radius-to-width-ratio. Once the vortices are annihilated (erased), the ring-shaped beam is focused with a thin lens and a Bessel-Gaussian beam is sculpted behind the lens’ focus [2,3]. We will present experimental and numerical evidences supporting the claims that: (i) these beams are long-range and quasi-non-diffracting, (ii) can be generated in both - continuous-wave beams and in the fields of ultrashort (femtosecond) laser pulses [4], (iii) the approach is non-wavelength-selective, independently of the used approach for generation highly-charged OVs - spiral phase or spatial light modulators, and (iv) can be created in femtosecond laser fields by generating the second harmonic of ring-shaped, strongly azimuthally modulated necklace beams Fourier-transforming them in space [5]. We believe that these results are of interest for e.g. free-space optical communications.

This research is based upon work supported by the Bulgarian Ministry of Education and Science as a part of National Roadmap for Research Infrastructure, project ELI ERIC BG. The work was also supported by the Bulgarian National Science Fund (project KΠ-06-H78/6) and was achieved partially thanks to equipment provided by the European Regional Development Fund within the Operational Programme “Science and Education for Smart Growth 2014-2020” under the Project CoE “National center of mechatronics and clean technologies” BG05M2OP001-1.001-0008-C01.

References:
[1] L. Stoyanov et al., European Physical Journal Plus 138, 702 (2023).
[2] L. Stoyanov et al., Scientific Reports 10, 21981 (2020).
[3] L. Stoyanov et al., Optics Communications 480, 126510 (2021).
[4] L. Stoyanov et al., Optics Express 29, 10997 (2021).
[5] N. Dimitrov et al., Photonics 12, 119 (2025).

Speaker: Prof. Alexander Dreischuh (Department of Quantum Electronics, Faculty of Physics, Sofia University, Sofia, Bulgaria, National Centre of Excellence Mechatronics and Clean Technologies, Bulgaria, and Bulgarian Academy of Sciences, Sofia, Bulgaria)

Biophysics, Life Sciences, Medical Physics

133 Integrated Platform for Single-Cell Electrical and Optical Characterization via Dielectrophoresis and Optical Tweezers

We present a novel, integrated platform for high-resolution single-cell biophysical characterization that combines dielectrophoresis (DEP) and optical tweezers (OT) within a single, synchronized experimental setup. This dual-modality system enables simultaneous, real-time extraction of both electrical and optical properties from individual, living cells in suspension—without the need for external calibration beads, fluorescent labels, or cell adhesion to surfaces. By integrating DEP and OT, we overcome the limitations of traditional bulk DEP approaches, which average responses across heterogeneous populations and obscure cell-to-cell variability. Our method provides clean, interpretable DEP spectra from single cells, allowing direct and quantitative computation of intrinsic electrical parameters such as membrane conductivity, membrane permittivity, and cytoplasmic conductivity.

The platform is specifically designed to accommodate optically and structurally complex cell types that challenge conventional spherical models used in DEP calibration. It supports repeated measurements on the same cell over time, enabling longitudinal studies of cellular responses to external stimuli, such as drug exposure or environmental changes

The method was validated by comparing DEP spectra obtained through the presented method with DEP spectra obtained on cell populations already validated methods. Moreover, OT stiffness measured by our method was validated by classical drag force measurements. All measurements were done on murine fibroblast cells NIH 3T3.

Importantly, our system is complemented by a suite of custom-built, open-source software tools for automated image-based cell tracking, real-time data acquisition, and finite element modeling of electric fields. It is compatible with a range of electrode geometries, offering flexibility in experimental design and integration with microfluidic platforms. Together, these features make the system broadly adaptable and scalable for diverse research applications.

To our knowledge, this is the first DEP-based technique capable of extracting such dielectric properties from live, non-adherent cells at single-cell resolution. Simultaneously, optical trap stiffness is measured dynamically, offering insight into optical properties (i.e., refractive index of the cell).

Overall, this platform represents a significant advancement in label-free, non-destructive single-cell analysis. By bridging electrical and optical profiling in a single assay, it opens new opportunities for basic research in cell biophysics, high-content screening, and the development of diagnostic and therapeutic technologies.

Speaker: Tudor Savopol (Biophysics and Cellular Biotechnology Department, Excellence Center for Research in Biophysics and Cellular Biotechnology, Faculty of Medicine, University of Medicine and Pharmacy Carol Davila, 8 Eroii Sanitari Blvd., Bucharest, 050474, Romania)

134 THE DOSIMETRIC IMPACTS OF CT-BASED AUTOCONTOURING ALGORITHM FOR BREAST CANCER RADIOTHERAPY PLANNING

PURPOSE:
In many institutions, tumors, and organs at risk contours are delineated manually; this is also costly and time-consuming. Recently, various automatic contouring methods have been developed to address these problems. However, these methods may not provide accurate contours for the physicians. One of the reasons is that most autocontouring algorithm results have been produced on CT images and are not optimal for the task of automated contouring.
Recently, artificial intelligence-based models have emerged that provide high accuracy in many anatomical regions in a shorter time. In study, it was aimed to dosimetrically evaluate the usability of a new generation autocontouring algorithm (DirectORGANS) that automatically identifies organs and contours them directly in the computed tomography (CT) simulator before creating breast radiotherapy plans.
METHODS:
The CT images of 30 patients were used in this study. All of the patients who underwent BCS (breast conserving surgery) were given radiotherapy. The breast as a target volume of 30 patients were automatically contoured based on DirectORGANS algorithm at the CT simulator. The CT scans were imported into the Eclipse treatment planning system for contouring. On the same CT image sets, the same breast volumes and contours of organs at risk were manually contoured RTOG-atlas based by an experienced physician and used as a reference structure. For each patient, volumetric arc therapy plans were generated using the reference contours (RefPlan). The dose scheme of 40 Gy/15 fractions were administered to the clinical target volume. The doses of manually delineated contours of the target volume and the doses of auto contours of the target volume were obtained from the dose volume histogram of the same plan.
To evaluate the target volumes, conformity index (CI) and homogeneity index (HI) were calculated. The Wilcoxon test was employed for statistical comparison with statistical package SPSS (P<0.05).
RESULTS:
Compared to the doses of the manual contours (MC) with auto contours (AC), there were statistically significant differences between HI and CI and clinical target volume covered by the 95% isodose line values due to differences in breast contouring (p < 0.001).
CONCLUSION:
To evaluate the dosimetric impact of using potentially inaccurate auto contours directly for treatment planning, the breast doses were evaluated from planned RefPlan. The current results indicate that automatically contoured breast target volume based on DirectORGANS algorithm is not reasonably concordant with clinician manual contouring based on RTOG Atlas. The differences between clinician contours and auto contours may be due to the DirectORGANS algorithm contour a larger breast volume than RTOG-atlas guidelines adhered to by clinicians. Consequentially, this volumetric discordance can cause meaningful dosimetric differences. Whilst DirectORGANS algorithm could be utilized as a starting point, contours will require modification by clinicians to conform to the RTOG atlas.

Speaker: Serap Çatlı Dinç (Gazi Üniversitesi Tıp Fakültesi)

abstractson.docx

135 Testing the reliability of gamma analysis used for the control of IMRT and VMAT plans with the incorrect dose method

Purpose Gamma index analysis and equipment are the most commonly used
methods and equipment for dosimetric control. Gamma index analysis is influenced
by multiple factors, and its accuracy is contingent upon various parameters and
variables. However, there has been limited research on how variations or errors in
dose delivery impact the results of gamma analysis, especially when conducted on
a faulty system. The purpose of this work is to determine Gamma Pass Rate (GPR)
consistency when across a dosimetric error and compare the different equipment
results. Method A total of 12 plans were selected. For each IMRT and VMAT plans dose
distribution measured with both electronic portal imaging device (EPID) and
MapCHECK 2 (MC2). 49 fields evaluated. These measurements are taken with 2
different output values (100 cGy = 100 MU / 104 cGy = 100 MU). %3/3mm and
gamma index > %95 used for the evaluation. Results All our measurements were pass at 100 cGy = 100 MU for the two
equipment. In case of 4% error (104 cGy = 100 MU), 38 fields were acceptable for
EPID and 15 fields were acceptable for MapCHECK 2. Many fields were acceptable
level even if there was an error in the dose. Conclusion It is important to realize the results of gamma index analysis are not
directly proportional to the decrease or increase at dose. Although the dose was
incorrect, the plans were found to be feasible. Also, the results may vary depending
on the equipment used. the presence of different results in each variable reduces
the reliability of the results. For this reason innovative approaches should be
investigated to improve results.

Speaker: selami eken

abstrackt3.pdf

136 DECOMMISSIONING AND CLEARANCE ASSESSMENT OF A DIAGNOSTIC AND THERAPEUTIC NUCLEAR MEDICINE DEPARTMENT IN ALBANIA

This paper presents the decommissioning process of a diagnostic and therapeutic nuclear medicine department located within “Mother Theresa” University Hospital. This department, operated for more than 25 years and served as the sole public provider of nuclear medicine services in the country, using radiopharmaceuticals based on iodine-131 and technetium-99m. Following the relocation of all clinical services to a newly constructed Hospital, a comprehensive radiation monitoring was conducted as part of the clearance protocol. Gamma dose rate measurements, alfa and beta contamination checks and swipe tests were performed across all clinical and storage areas. The results indicated no presence of contamination above national and international clearance levels. This work provides a practical case study on the safe closure and radiological assessment of a nuclear medicine facility and may serve as a guideline for similar future activities in diagnostic imaging and radionuclide therapy services.

Speaker: Brikena Vucaj (University Hospital Centre "Mother Tereza")

Abstract Brikena.docx

137 Perspectives on Breast Cancer Diagnosis Assisted by Convolutional Neural Networks Applied to High-Sensitivity Talbot-Lau Interferometric Imaging

Early detection of breast cancer remains a crucial objective in modern medicine. High-sensitive X-ray imaging based on Talbot-Lau interferometry offers enhanced soft-tissue contrast compared to conventional mammography, making it a promising tool for non-invasive diagnostics. This work explores the integration of Convolutional Neural Networks (CNNs) with high-sensitivity Talbot-Lau imaging to support and improve automatic tumor detection.
We propose a methodological approach consisting of three parts: pre-processing and filtering of raw images to enhance the contrast-to-noise ratio (CNR); classification of scattering images using a ResNet50 model to distinguish between tumors, calcifications, and fibrous tissue; and a precise segmentation of tumor regions using a U-Net architecture.
Experimental results demonstrate a significant improvement in both detection accuracy and lesion localization. These findings highlight the considerable potential of integrating advanced phase-contrast imaging with deep learning techniques as a possible decision-support tool for breast cancer screening and diagnosis.

Speaker: Ionuț-Cristian Ciobanu (Horia Hulubei National Institute for Physics and Nuclear Engineering)

138 3D Mapping of Folate-Functionalized Silica Nanoparticles in Cells via Combined Fluorescence, Dark Field, and Hyperspectral Microscopy

The development of efficient drug delivery systems is important in modern medicine to improve therapeutic efficacy while minimizing side effects. Among various nanocarriers, mesoporous silica nanoparticles (MSNs) have emerged as versatile platforms due to their high surface area, tunable pore size, and capacity for surface modification. Surface functionalization of MSNs with targeting ligands, such as folic acid, enhances their specificity by exploiting receptor-mediated endocytosis – particularly in cancer cells that overexpress folate receptors.
Targeted delivery becomes especially valuable in the administration of potent chemotherapeutics like Irinotecan (Iri), a topoisomerase I inhibitor widely used in colorectal cancer treatment. However, its systemic toxicity poses significant challenges. By encapsulating Iri within MSNs and decorating them with folate, it is possible to achieve selective cytotoxicity toward tumor cells while sparing healthy tissue.
This in vitro study aims to assess both the cytotoxic potential and intracellular mapping of folate-functionalized, Iri-loaded MSNs. By combining advanced imaging techniques, including hyperspectral and fluorescence-based enhanced dark field microscopy, with quantitative image analysis, this research investigates how nanoparticle surface chemistry influences cellular uptake and subcellular localization in cancerous versus non-cancerous cells.
Caco-2 (human colon adenocarcinoma) and NIH3T3 (mouse fibroblast) cells were used as cancerous and non-cancerous models, respectively. After 24 hours of seeding, the cells were incubated with the folate-functionalized, Iri-loaded MSNs for 24 or 48 hours continuously (24h+, 48h+). A separate experimental category was assigned to a discontinuous incubation with the nanoparticles, after the first 24h of incubation the culture medium containing MSNs being replaced with physiological culture medium (24h+/-). Cell viability was measured at mitochondrial level using the colorimetric MTS assay (formazan based).
Microscopy analyses were conducted using enhanced dark field microscopy (eDFM) from Cytoviva®, operating in hyperspectral imaging (HSI) and fluorescence imaging modes. Fluorescence imaging included cytoskeletal staining with AlexaFluor488 Phalloidin and nuclear staining with DAPI, enabling 3D reconstruction of cellular structures. For hyperspectral analysis, non-stained Caco-2 cells were examined and spectral profiles at pixel level were generated. Image processing was done using Cytoviva® software and custom MATLAB routines leading to 3D cell reconstructions and quantifications of MSN localization in nuclear and cytoplasmic regions.
Folate-functionalized MSNs demonstrated significantly enhanced cytotoxicity compared to non-functionalized controls, with greater effects observed in Caco-2 cells than in NIH3T3 cells. This outcome aligns with the known overexpression of folate receptors in cancer cells. Hyperspectral and fluorescence microscopy revealed that folate conjugation facilitated greater MSN uptake and preferential localization near the nucleus. The custom image analysis pipeline enabled detailed 3D visualization and quantification of MSNs within cellular compartments.
This study demonstrates that folate-functionalized, non-fluorescent MSNs significantly enhance the delivery and cytotoxicity of Irinotecan, particularly in human colon adenocarcinoma cells. The application of advanced microscopy techniques, combined with a novel processing approach for Z-stack images, enabled quantitative evaluation of nanoparticle uptake and intracellular distribution. These findings highlight the potential of folate-targeted MSNs for efficient and selective cancer therapy.

Acknowledgments: This work was supported by projects PN-III-P2-2.1-PED2019 (contract no. 525PED/2020) and Project No. P_36_611, MySMIS code 107066.

Speaker: Luminita Claudia Miclea (Biophysics and Cellular Biotechnology Department, Excellence Center for Research in Biophysics and Cellular Biotechnology, Faculty of Medicine, University of Medicine and Pharmacy Carol Davila, 8 Eroii Sanitari Blvd., Bucharest, 050474, Romania)

Condensed Matter, Materials and Applied Physics

139 Towards the Shockley-Queisser limit for single-junction crystalline silicon based solar cells

In 2024, the newly installed photovoltaic solar power plant capacity was about 600GWp, together with this the
total global PV power capacity was over 2 Terawatt peak. In 2025, it is expected that a new photovoltaic
installation could reach 700Gwp in 2025 [1]. The last two decades, p-n junctions manufactured on single
crystal (mono) silicon wafers have been dominating silicon photovoltaic (PV) cells technologies with over 95%
share [2]. The scenarios for annual global PV installations towards 2050 have been made according to the new
and innovative technologies and cost reduction. In the case of high technology and innovation scenario, a CAGR
is expected to be ~6% and the 2050 annual would reach ~1000GWp [3]. In 2024 in Türkiye, the cumulative
solar power plant installations have overpassed 20GWp, and the 77Wp planned cumulative PV power
installations in the next ten years is announced in 2025 [4].
For a single-junction PV cell, the maximum theoretical the Shockley-Queasier efficiency limit efficiency is
around 33.7%. Towards the Shockley-Queisser limit for single-junction crystalline silicon based solar cells
efficiencies with commercially acceptable stabilities have been a challenge for over the years. [5]. In recent
decades, the evolution of PV cell technologies on single crystalline silicon had been starting from Aluminium
Back Surface Field (Al-BSF), continuing as Passivated Emitter and Rear Contact (PERC), Passivated Emitter Rear
Totally-Diffused (PERT), Tunnel Oxide Passivated Contact (TOPCon), Heterojunction Technology (HJT),
Interdigitated Back Contact (IBC), Heterojunction Back Contact (HBC), Metal-wrap through (MWT), Tunnelling
Oxide Passivated Back Contact (TBC). Although each technology has its own manufacturing, stability and
commercial strengths and weaknesses [6,7].
This review discusses the technological differences in the front runner silicon photovoltaic cells and makes an
attempt to foresee a direction of the race in short-term, mid-term and long-term utilizing the available data
and reviews in 2025.

Speaker: Prof. Şener Oktik (Maltepe University)

Abstract_Sener Oktik 02.05.2025.pdf

140 Quantum dynamics of phonon-limited charge and energy transport: Numerically exact and approximate approaches*

Recent interest in quantum dynamics of electronic excitations in molecular semiconductors and photosynthetic molecular aggregates [1] is motivated by the prospect of optoelectronic applications that could harness quantum effects and enhance charge and energy transport. Typically, the coupling of charges or excitons to quantum lattice vibrations lies in the intermediate regime, whose reasonable description necessitates computationally expensive numerically exact approaches. Meanwhile, coupled electronic–vibrational dynamics occurring on a wide range of timescales is inaccessible to most existing methods, suggesting a need for new (approximate) approaches.
In this talk, I give a synthetic overview of my recent methodological breakthroughs [2–4] concerning electronic quantum dynamics in the field of phonons.
I present the applications of the numerically exact hierarchical equations of motion (HEOM) method to the Holstein [2] and Peierls models [3]. I discuss how to overcome the method’s numerical instabilities stemming from strong non-Markovian effects [2] and handle the phonon-assisted current in the Peierls model [3]. These developments enable us to answer long-standing questions such as the importance of vertex corrections to conductivity in the Holstein model [2] or the appropriateness of the transient localization scenario for charge transport in the Peierls model [3]. Finally, I show how the synergy between the theory of open quantum systems and diagrammatics of condensed matter physics can be used to devise an approximate approach to exciton dynamics in multichromophoric aggregates [4]. I discuss the application to laser-triggered exciton dynamics the Fenna–Matthews–Olson complex immersed in a realistic structured bosonic environment.

[1] T. Nematiaram and A. Troisi, J. Chem. Phys. 152, 190902 (2020); J. Cao et al., Sci. Adv. 6, eaaz4888 (2020).
[2] V. Jankovic, J. Chem. Phys. 159, 094113 (2023); V. Jankovic, P. Mitric, D. Tanaskovic, and N. Vukmirovic, Phys. Rev. B 109, 214312 (2024).
[3] V. Jankovic, arXiv:2501.05054 (2025); 2501.05055 (2025).
[4] V. Jankovic and T. Mancal, J. Chem. Phys. 161, 204108 (2024).

*This research is supported by the Science Fund of the Republic of Serbia (Grant No. 5468—PolMoReMa) and Serbian Ministry of Science.

Speaker: Dr Veljko Jankovic (Institute of Physics Belgrade, University of Belgrade, Serbia)

141 Theoretical Insight into Strongly Suppressed Thermal Conduction in Fully Dense Crystalline Solids

The thermal properties of materials are important for the development of various modern technologies. In particular, thermoelectric energy conversion and thermal barrier require materials with ultra-low thermal conductivity. Lattice vibration dominates heat transport in insulating solids; recent theoretical studies suggested that both propagation and diffuson-like behaviors of phonons can play a critical role when the phonon mean free path is close to the atomic distance. In this presentation, I will discuss abnormal thermal transport behaviors in complex argyrodite compounds and our theoretical insight into the phenomena. Based on the more in-depth understanding, we propose alternative principles to explore fully dense crystalline solids with ultra-low thermal conductivities. We performed our research based on the thermal transport unified theory, first-principles calculations of anharmonic lattice dynamics, and machine-learned interatomic potentials. This presentation will focus on discussing nonconventional phonon transport mechanisms in technologically important solids.

Speaker: Yue Chen (The University of Hong Kong)

142 Nonlinear excitation interaction with extended inhomogeneities in anisotropic ferromagnets

The effect of the interaction of nonlinear excitations with extended inhomogeneities in an on-site anisotropic Heisenberg spin chain is probed numerically. Inhomogeneity corresponds to a segment consisting of consecutive spins on the chain that are subjected to an inhomogeneous magnetic field. To describe the behavior of the spin chain, we derive the nonlinear Schrödinger equation (NLS) of the spin amplitude for classical spin vectors and wide nonlinear excitations. For a homogeneous chain with an easy axis anisotropy the NLS possesses a bright soliton solution. It is found that homogeneities with positive coefficients act as a potential barrier and yield transmission or reflection of the incident soliton. When the coefficients are negative, the extended inhomogeneities act as potential wells and for a given range of parameters the interactions exhibit periodically repeating windows of transmissions and trapping as a function of the length of the inhomogeneous segment. The observed scattering patterns have been explained in terms of the frequency and decay analyses of the shape oscillations of the soliton within the inhomogeneity. It is shown that the outgoing soliton follows a resonance between the period of oscillations and the length of the inhomogeneity.

Speaker: Hassan Chamati (Institute of Solid State Physics, Bulgarian Academy of Sciences)

BPU2025.docx

143 Temporal Airy Pulses for Precision Processing of High-Bandgap Dielectric Materials

High bandgap materials like fused silica and soda-lime glass are widely utilized in optics, optoelectronics, and microfluidics due to their advantageous properties, such as transparency, thermal stability, and chemical resistance. However, conventional methods of processing these materials pose significant challenges. Ultrashort pulse lasers are now essential for precise micromachining of these materials, due to their ability to induce nonlinear absorption with minimal thermal damage. Bandwidth-limited pulses with Gaussian temporal and spatial profiles predominantly result in surface ablation craters when interacting with dielectric materials. Our previous study demonstrated that Temporal Airy Pulses (TAP), generated by imposing cubic spectral phase on 30 fs pulses from a Ti:Sapphire laser at 790 nm, enabled sub-diffraction-limited processing of fused silica [2]. A theoretical model was also developed to explain how positive and negative TAP modulate the balance between multiphoton and avalanche ionization during laser-induced breakdown [1]. This model was experimentally validated by time-resolved measurements of transient electron plasma density [3].
In this study, we expand TAP to address the precision dicing of ultrathin soda-lime glass plates. We conducted a comparative analysis of three distinct pulse types: bandwidth-limited (BWL) of 30 fs pulses and TAP with positive and negative cubic phase of 600,000fs (TAP+ and TAP-). These pulses were evaluated at various fluences and two focusing conditions, 50× and 20× microscope objectives. The performance of the cutting process was evaluated by measuring the breaking force using a custom four-point bending setup. We also assessed the surface and cross-sectional quality through visual analysis using optical microscopy.
Our findings show that TAP+ provides clean, flat-cut edges with superior breaking strength, significantly outperforming BWL and TAP- pulses [4]. A close examination of these results suggests that TAP laser processing has the potential to serve as a promising non-contact alternative to mechanical cutting methods, particularly in the context of thin dielectric and semiconductor substrates.

Speaker: Cristian Sarpe

Environmental and Solar Physics, Meteorology and Geophysics

144 Enhancing air pollution level assessment with community-based air quality monitoring network data – case study for Brasov City, Romania

Air pollution in Brasov city is a subject of high interest for authorities and researchers due to its impact on human activities as well as due to the specific conditions found in this region – from geographical conditions affecting the pollutant dispersion to the sustained high air pollution levels. Of particular concern were the infringement procedures from the European Commission against Romania for not assuring a proper level of air quality for the population – in particular with respect to PM10 and NO2 pollutants - not only in Brasov, but also in other major cities (e.g., Bucharest, Iasi) (Iorga, 2021), especially during the period 2007-2020. Among the response measures, the City Hall in collaboration with community-based UradMonitor network (www.uradmonitor.com) (Velea et al, 2023) started to provide, from 2022, a real-time information service to citizen on air quality status. The present analysis investigates the added-value of these measurements in assessing the air pollution level at yearly and monthly scale, as well as with respect to high-pollution events. To this end, community-based PM10 and PM2.5 measurements, covering the period 2022-2023, are used to build three indicators recommended by the European Environment Agency (EEA), namely the annual mean (P1Y), monthly mean (P1M) and 3-consecutive days exceeding concentration thresholds (P1Y-3daysAbove). Data from the national monitoring network (www.calitateaer.ro) is used as reference. The results highlight the increased capability of higher-density community-based network to characterize the spatial distribution of pollution level within the city and to identify high-pollution events. These features open opportunities for a spatially detailed characterization of air pollution hazard, which, combined with socio-economic data, may provide the basis for an air-pollution risk assessment. Preliminary results of this approach are also presented.
The results are partly obtained in the project Climate-Resilient Development Pathways in Metropolitan Regions of Europe (CARMINE), funded by the Εuropean Union under the Horizon Europe Programme (Grant agreement 101137851).
Keywords: air pollution, PM10, PM2.5, hazard, risk assessment, Brasov city
References
Velea, L., Udriștioiu, M.T., Puiu, S., Motișan, R., Amarie, D. (2023): A Community-Based Sensor Network for Monitoring the Air Quality in Urban Romania. Atmosphere, 14, 840. https://doi.org/10.3390/atmos14050840 (Q3)
Iorga, G. (2021). Air Pollution and Environmental Policies, EU and Romania: Where We Stand, What the Data Reveals, What Should Be Done in the Future?. In: Todor, A., Helepciuc, F.E. (eds) Europeanization of Environmental Policies and their Limitations. Springer, Cham. https://doi.org/10.1007/978-3-030-68586-7_4

Speaker: Liliana Velea (Administratia Nationala de Metorologie, Romania)

LVelea-et-al-BPU2025-abstract.docx

145 RISK ASSESSMENT AND MANAGEMENT STRATEGIES FOR RADON AND THORON EXPOSURE IN SOME HEALTHCARE ENVIRONMENTS IN KOSOVO

Abstract
Indoor exposure to radon and thoron in healthcare environments, such as hospitals and clinics, is a significant concern due to the potential health risks to patients and staff. This study aims to measure and analyze the activity concentrations of radon and thoron and calculate the values of the effective dose received from patients and staff in selected healthcare facilities across Kosovo, using both active and passive detection methods. The findings of this study will provide insights into the potential health risks associated with prolonged exposure to elevated radon and thoron levels in healthcare settings. Based on the results we will propose strategies for mitigating radiation exposure, such as improving ventilation systems and implementing regular monitoring protocols, to enhance the safety and well-being of both patients and healthcare workers.

Keywords: healthcare, radiation protection, risk assessment, radon, thoron

Speaker: Ylli Kaçiu

BPU_2025.docx

146 A Synoptic Analysis of Severe Weather Events in South-Western Romania. Case studies: 13 June 2024, 6 and 8 May 2025.

Severe convective events are often driven by specific synoptic patterns, which influence the initiation, further development, and movement direction of the cloud structures that generate them. The days of June 13, 2024, and May 6 and 8, 2025, brought such phenomena: heavy rainfall over short periods of time, frequent lightning, and in some areas, strong wind gusts and medium to large hail (also wind-driven hail), which caused various material damages in southern Romanian counties (the regions of Banat, Oltenia, and Muntenia).
This study presents the synoptic patterns that favored the development of west-northwest to east-southeast (WNW–ESE) moving mesoscale convective systems, which triggered severe weather events in southern Romania.

Speakers: Mr Alexandru Cristian Szatmari, Mr Elias Andrei Călugăru, Mr Sergiu Daniel Pavel (National Meteorological Administration of Romania)

147 Danube Wetlands Restoration: Expected Impacts with regard to Climate Changes

Human activities have negatively affected more than 70% of the Danube wetlands. Their restoration will benefit ecosystem services, including wetland and river biodiversity and carbon sequestration. The European Commission’s Mission “Restore our ocean and waters by 20230” targets not only Danube and Black Sea areas, but also meets a number of the UN sustainable development goals (SDGs), such as climate resilient cities, nature conservation of land and waters, access to resources and wellbeing of the local population. In addition, Black Sea Basin wetlands and floodplains contribute fish resources, ensure flood prevention and mitigation, biomass production, water purification, and reduction of eutrophication processes. European Commissin international collaborative research and innovation projects support scientists in their interdisciplinary studies of the Danube River Basin – one of Europe’s largest (801.463 km²) basins, which drains areas and affects nature and human wellbeing in 19 countries.
The DaWetRest (Danube Wetlands and flood plains Restoration through systemic, community-engaged, and sustainable innovative actions) project (Grant 101113015) performs research and innovation actions to improve the linkage of the Danube and its tributaries with the neighboring wetlands. Its activities include the use of new methods and technologies for freshwater monitoring and governance of fresh and brackish water ecosystems. Specific efforts take the engagement and active participation of the local communities in the research and innovation activities to higher levels.

Speaker: Ekaterina Batchvarova (Climate, atmosphere and water research institute at Bulgarian Academy of sciences)

High Energy, Particle Physics, Gravitation and Cosmology

148 Extended Standard Model as a 2HDM with six fermion generations

Based on two recent papers [1]-[2] we discuss the enlarging of the Standard Model - up to six fermion generations and two different Higgs doublets, while keeping the same gauge group $SU(3)_{c}\otimes SU(2)_{L}\otimes U(1)_{Y}$ undergoing the SSB to $SU(3)_{c}\otimes U(1)_{em}$ - in order to have it predicting (i) the quantization of both electric and weak charges; (ii) the muon anomalous magnetic moment discrepancy; (iii) the appropriate massive neutrinos ensuring the seesaw mechanism; (iv) the unaltered CKM matrix in the quark sector; (v) the FCNC cancellation; and (vi) a viable Higgs spectrum providing us with two breaking scales - the old SM one $v\simeq 246$ GeV and a new one at about $V\simeq 1-100$ TeV.

[1] A.Palcu, J. Phys. G: Nucl. Part. Phys. 48, 055003 (2021).
[2] A.Palcu, J. Phys. G: Nucl. Part. Phys. 51, 065002 (2024).

Speaker: Adrian Palcu ("Aurel Vlaicu" University of Arad)

149 Insights into freeze-out properties of systems produced in relativistic heavy-ion collisions

An important way to characterize the overall features of high-energy nuclear collisions is to analyze the transverse momentum distributions of produced particles. In these collisions, the differences in shape between the positive and negative pion transverse momentum spectra at low pT can be used to study the Coulomb final-state interaction. The charged pions, as the most abundantly produced and lightest species, are the particles most strongly influenced by the Coulomb field generated by the positive net-charge of the stopped participant protons. The effects of the Coulomb interaction on charged pion production in Au+Au collisions at sqrt(sNN)=2.4 GeV and measured with HADES experiment are investigated. The negative-to-positive pion ratios as a function of transverse momentum are obtained and used to analyze the Coulomb interaction. The “coulomb kick” (a momentum change due to Coulomb interaction) and initial pion ratio for different rapidity intervals were obtained. In order to study the non-equilibrium degree of these collisions, the pT spectra are studied using Tsallis distribution as a parametrization. The rapidity dependence of the Tsallis fit parameters, Tsallis temperature, and non-extensivity parameter, a parameter characterizing the degree of non-equilibrium for the systems produced in these collisions will be presented. These results are connected with the kinetic freeze-out dynamics.

Speaker: Oana Ristea (University of Bucharest, Faculty of Physics)

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150 Recent Results on Standard Model Physics from CMS

The LHC experiments provide measurements of Standard Model production cross sections with unprecedented precision, which is essential for making new discoveries and exploring potential new physics. These measurements offer crucial input for cutting-edge theoretical model calculations, as well as for the development of new models. This presentation reviews recent Standard Model physics measurements from the CMS experiment, with a focus on QCD and electroweak phenomena.

Speaker: Nataša Raičević (University of Montenegro)

Raicevic_BPU12.pdf

151 Nonlocal de Sitter gravity and its verification

Despite its great success, the general theory of relativity is not the final theory of gravity. In addition to other problems, some shortcomings of the standard model of cosmology led to the search for a more general theory of gravity. One of the promising lines of research is the nonlocal theory of gravity. In this talk, I will present a simple nonlocal de Sitter gravity, its several exact vacuum cosmological solutions and an approximate solution for describing the rotation curves of spiral galaxies. One of cosmological solutions mimics effects that are usually assigned to dark matter and dark energy. Some other cosmological solutions are examples of the bounce and cyclic universes. The rotation curves of the Milky Way and M33 spiral galaxy, as well as some other aspects, will be also presented.

Based mainly on joint work with I. Dimitrijevic, Z. Rakic and J. Stankovic:

1. PLB 797 (2019) 134848, arXiv:1906.07560 [gr-qc].
2. JHEP 12 (2022) 054, arXiv:2206.13515 [gr-qc].
3. Symmetry 16 (2024) 544, arXiv:2404.05848 [physics.gen-ph].

Speaker: Prof. Branko Dragovich (Institute of Physics, University of Belgrade, Belgrade, Serbia)

Dragovich.Abstract,BPU.8-12.25.docx

152 Investigating small collision system properties using balance functions

Two particle correlations have shown the presence of long-range rapidity correlations in small collision systems. Several other measurements provided insight into the unexpected collective behaviour similar to the one exhibited in heavy-ion collisions. These properties can be explained by several models, which consider a microscopic description like PYTHIA 8 and a macroscopic treatment as EPOS4. Balance functions have been regarded in the past as a method of investigating the late-stage hadronization found in the presence of a strongly-coupled medium. We present balance functions confronting EPOS4 and PYTHIA 8 in pp collisions at $\sqrt{s} = 13.6$ TeV to distinguish between these models.

Speaker: Alexandru Manea (Institute of Space Science)

BPU12_AManea.pdf

153 Polarimetric Signatures in Microlensing Events Induced by Primordial Black Holes in the Roman Space Telescope Survey

Microlensing is an effective tool for constraining the properties of compact dark matter candidates, such as Primordial Black Holes (PBHs). Standard photometric observations of microlensing events offer valuable insights into the mass and spatial distribution of PBHs. However, degeneracies among lensing parameters often limit the precision of these measurements. A promising approach to alleviate these limitations involves detecting polarization signals generated during microlensing events.

 In this study, we investigate the expected polarimetric signatures of PBH-induced microlensing events, focusing on those that may be identified through photometric monitoring by the upcoming Nancy Grace Roman Space Telescope (Roman). The strength of the polarization signal depends on the geometry of the source–lens system and the structure of the circumstellar envelope. The signal typically reaches its maximum when the lens passes near the outer edge of the envelope—a configuration that can be effectively probed using high-sensitivity ground-based polarimeters such as FORS2 at the Very Large Telescope (VLT).

  Using Monte Carlo simulations, we model a population of PBHs distributed according to a Galactic halo profile. The source stars are assumed to be cool red giant branch (RGB) stars, each surrounded by an extended dusty envelope that generates intrinsic polarization through scattering by dust and molecules. Given Roman’s photometric precision and its planned survey of the Galactic center, we find that PBHs with masses in the range of 10⁻⁵ to 10 M☉ are most likely to induce detectable polarization in RGB stars. Our simulations indicate a polarization detection probability of approximately 8.4%, underscoring the importance of ground-based polarimetric follow-up with instruments like VLT/FORS2 for placing tighter constraints on the PBH population in the Milky Way.

Speaker: Prof. Lindita Hamolli (Department of Physics, University of Tirana, Albania)

13:00 Lunch Break

Poster Session 3

154 Exploring X17 and dark charges in the context of Standard Model tension

We demonstrate how the hypothetical X17 boson could influence the muon g−2 anomaly and the Lamb shift. Furthermore, by considering kinetic mixing between this new boson and the U(1)Y gauge field, we establish a possible contribution of the X17 to the W boson mass

Speaker: Raoul Serao (University of Salerno and INFN)

155 55 years of relativistic heavy ion collisions with accelerator systems. Contributions of the Faculty of Physics from the University of Bucharest

In 1948 Dr. Phyllis Freier and his team discovered the relativistic heavy ions component of the primary cosmic rays. A new field in Nuclear and Particle Physics became. In August 1970, the first heavy ions beam was used at the JINR Dubna to evidence the cumulative negative pions production in d-C collisions at 5 A GeV, using a linear accelerator and the Synchrophasotron U-10. Members of the Atomic and Nuclear Physics Chair staff were involved in these experiments. Since the beginning of the accelerator systems era, other important laboratories have been involved in research in this fascinating field High Energy Physics and Nuclear Physics. Members of the chair staff have been involved during this time in a few international experiments.
Taking into account these facts, in this work, a synthesis of the interesting results obtained in more than 5 decades, beginning with experiments from JINR Dubna and continuing with SPS-CERN, BNL-RHIC experiments, as well as the expectations from CBM Experiment at GSI-FAIR, will be presented.

Speaker: Alexandru Jipa (University of Bucharest, Faculty of Physics, Department of Structure of Matter, Earth and Atmosphere Physics, Astrophysics)

156 Albania National Radioactive Waste Storage Facility Contamination Monitoring

The Albanian National Radioactive Waste Storage Facility (NRWSF) is operated by the Institute of Applied Nuclear Physics (IANP) in accordance with internationally acceptance criteria, and is situated within IANP territory. This facility consists of two main parts: a] operational area; b] interim storage facility (area). Apart from office and sanitary space the building contains the following areas: An area for preparing the cement mixture at the top of the drawing; a waste receipt area for checking delivered waste and their documentation; an operating area for conditioning the wastes; a decay-storage area for waste with short half-lives; an operational storage area for the storage of delivered wastes prior to their conditioning.

The Albanian National Radioactive Waste Storage Facility (NRWSF) is licensed to receive low level waste/intermediate level waste (LLW/ILW) of non-nuclear power plant origin (health care, industry, agriculture, education and research).

In the IAEA TC Programme cycle 2018-2019 Albania had a National Project ALB 9010 titled “Upgrading the Radioactive Waste Storage Building According to International Standards”. In the frame of this project since 2018 was prepared and implemented a Radiological Monitoring Program for the National Radioactive Waste Storage Facility. This monitoring programme included contamination control of the NRWSF floor surface, conditioned drums surface and of DSRS surface contamination by Smear Test.

All the contamination monitoring results showed that there is no contamination in the floor surface, on the conditioned drums or DSRS stored inside NRWSF. These results show that the operation of the storage facility is safe for the environment, public and employes working in Albanian National Radioactive Waste Storage Facility.

Speaker: Prof. Kozeta Tushe (Institute of Applied Nuclear Physics, Tirana University)

157 Dynamics of Amyloid Beta Protein Signaling under Complexity Reduction: A Mathematical Modeling and BooleSim Simulation Approach

Understanding how complex biological systems behave over time is essential for predicting their future states, especially in diseases like Alzheimer’s disease. Mathematical modeling of such systems offers a valuable approach to exploring not only the theoretical aspects of network behavior but also their biological and medical implications. This study investigates how reducing the complexity of the Amyloid Beta (Aβ) signaling pathways influences its dynamic behavior, using a Boolean network model built from data curated in the SIGNOR database. Boolean rules were applied, and network simulations were performed in BooleSim under different initial conditions reflecting healthy and disease-related cellular states. Complexity reduction involved removing non-essential interactions and simplifying regulatory motifs. Our findings show that while simplification can shorten the time to reach steady states, it may also result in the loss of important regulatory pathways, potentially affecting the biological validity of the model. Nevertheless, key nodes such as BACE1 and GSK3β retained their functional significance even in the simplified models, confirming their central role in Alzheimer’s pathology. Simulated interventions targeting these molecules disrupted apoptosis-related signaling patterns, highlighting their relevance as potential therapeutic targets, consistent with current Alzheimer’s drug development strategies targeting BACE1 and GSK3β. This work illustrates how careful simplification of biological networks can offer a practical framework for modeling complex neurodegenerative processes at the intersection of biology and computation.

Keywords: Mathematical modeling, Complexity, Alzheimer’s disease, Boolean model, Signaling pathway

Speaker: Dr Inva Kociaj (Western Balkans University)

Kociaj-Poster - Presentation-paper BPU.pdf

158 Efficient U-Net Model on FPGAs: A VitisAI Approach with Xilinx ZCU104

Field programmable gate arrays (FPGA) are reconfigurable and serve as prototyping platforms for application-specific integrated circuits (ASIC). FPGA are composed of configurable logic blocks and programmable interconnects and allow rapid testing of digital designs. Many challenges in medical field, in agriculture and in security are solved by the implementation of artificial intelligence techniques in high performance computing units with an inherently higher quantitative accuracy than any user. The implementation of these techniques on portable computing units (including FPGA) has gained great attention in the new field of tinyML. Here, we present an efficient FPGA implementation of UNET architecture segmentation of unstained brightfield cell images achieving a 97% accuracy. Quantization and pruning are used by effectively reducing the model size without a significant decrease in the accuracy. This work indicates the importance of combining algorithmic based compression techniques with hardware-aware optimizations.

Keywords: FPGA, tinyML, deep learning, Medical image segmentation.

References:

[1] Ng, W. S., Goh, W. L., & Gao, Y. (2024, May). High Accuracy and Low Latency Mixed Precision Neural Network Acceleration for TinyML Applications on Resource-Constrained FPGAs. In 2024 IEEE International Symposium on Circuits and Systems (ISCAS) (pp. 1-5). IEEE.
[2] Uka, A., Topalli, G., Hoxha, J., & Vrana, N. E. (2021). FPGA Implementation of Filters in Medical Imaging. In BIODEVICES (pp. 195-200).
[3] Prakash, S., Callahan, T., Bushagour, J., Banbury, C., Green, A. V., Warden, P., ... & Reddi, V. J. (2023, April). Cfu playground: Full-stack open-source framework for tiny machine learning (tinyml) acceleration on fpgas. In 2023 IEEE International Symposium on Performance Analysis of Systems and Software (ISPASS) (pp. 157-167). IEEE.

Speaker: Arban Uka (Epoka University)

BPU12_UKA_FPGA_Poster.pptx

Uka_et_al_FPGA.docx

159 Evaluating the robustness of the Hopfield Neural Networks against noise in Image Classification

Griselda Alushllari 1, Arban Uka 1, Margarita Ifti 2, Alvin Kollcaku 1
1 Department of Computer Engineering, EPOKA University, Tirana, Albania
2 Department of Physics, Tirana University, Tirana, Albania

Abstract

Hopfield neural networks (HNN) are fully connected networks of binary neurons that can store patterns in an energy landscape. Collective properties of large systems are only weakly sensitive to details and this property can be used to test the robustness of HNN to noise. In this work their robustness to various types of noise in classification tasks is evaluated. While HNNs have demonstrated remarkable pattern recognition capabilities through their associative memory properties, their vulnerability to noise-induced parasitic memories remains a significant challenge, particularly in high-dimensional classification problems. We propose a comprehensive framework for evaluating HNN resilience by examining the interplay between noise tolerance and the formation of parasitic attractor states that can compromise classification accuracy. The experiments are conducted on MNIST dataset classifying numbers and on unstained brightfield BALB 3T3 cell images classifying them based on health state. An attention based memory module that allows dynamic associative retrieval and a Hopfield classifier are used to integrate learned memory slots with deep visual features. Validation accuracy of 95.83% was achieved for the classification of cell images. Memory slot ablation is used to determine the essential memory patterns for robust cell classification.

References

1. Hopfield, J. J. (1982). Neural networks and physical systems with emergent collective computational abilities. Proceedings of the national academy of sciences, 79(8), 2554-2558.
2. Uka, A., Ndreu Halili, A., Polisi, X., Topal, A. O., Imeraj, G., & Vrana, N. E. (2021). Basis of image analysis for evaluating cell biomaterial interaction using brightfield microscopy. Cells Tissues Organs, 210(2), 77-104.
3. Ramsauer, H., Schäfl, B., Lehner, J., Seidl, P., Widrich, M., Adler, T., ... & Hochreiter, S. (2020). Hopfield networks is all you need. arXiv preprint arXiv:2008.02217.
4. Krotov, D. (2023). A new frontier for Hopfield networks. Nature Reviews Physics, 5(7), 366-367.
5. Uka, A., Polisi, X., Barthes, J., Halili, A. N., Skuka, F., & Vrana, N. E. (2020, August). Effect of preprocessing on performance of neural networks for microscopy image classification. In 2020 International Conference on Computing, Electronics & Communications Engineering (iCCECE) (pp. 162-165). IEEE.

Speaker: Griselda Alushllari (Epoka University)

HNN_poster.pdf

160 Evaluation of parameters of different architectures for segmentation of cell images

Griselda Alushllari 1,2, Arban Uka 1, Margarita Ifti 2
1 Department of Computer Engineering, EPOKA University, Tirana, Albania
2 Department of Physics, Tirana University, Tirana, Albania

Abstract

Unstained brightfield images pose a significant challenge for image analysis. U-Net architectures are a family of fully convolutional neural network which are used for image segmentation. These architectures are widely used for segmenting biomedical images due to their ability to detect fine spatial details in microscopy data. Understanding the impact different biomaterials have on cell images requires reliable segmentation methods. In this study, different architectures are used to segment brightfield microscopy images to determine cell confluence and assess the impact of various biomaterial concentrations on cell health. Results were compared for different loss functions, batch sizes to identify the optimal parameters for cell segmentation. Manual labelling of the images from an original dataset was conducted under the supervision of the medical practitioners. Among all the trained models, the ones achieving highest accuracy results were chosen for further analysis and cell confluence. Hybrid function with different weights of a combination of binary cross entropy and dice loss was found the best one.

References

1. Caicedo, J. C., Goodman, A., Karhohs, K. W., Cimini, B. A., Ackerman, J., Haghighi, M., ... & Carpenter, A. E. (2019). Nucleus segmentation across imaging experiments: the 2018 Data Science Bowl. Nature methods, 16(12), 1247-1253.
2. Uka, A., Ndreu Halili, A., Polisi, X., Topal, A. O., Imeraj, G., & Vrana, N. E. (2021). Basis of image analysis for evaluating cell biomaterial interaction using brightfield microscopy. Cells Tissues Organs, 210(2), 77-104.
3. Uka, A., Polisi, X., Barthes, J., Halili, A. N., Skuka, F., & Vrana, N. E. (2020, August). Effect of preprocessing on performance of neural networks for microscopy image classification. In 2020 International Conference on Computing, Electronics & Communications Engineering (iCCECE) (pp. 162-165). IEEE.
4. Duro, X. P., Uka, A., Alushllari, G., Halili, A. N., Karras, D. A., & Vrana, N. E. (2025). Optimizing combination of feature extraction and classifiers in supervised classification of cells images. Edelweiss Applied Science and Technology, 9(2), 682-707.

Speaker: Griselda Alushllari (Epoka University)

Poster_UNET2.pdf

161 Mathematical Model for Asymmetrical Pulses Passing through Active Medium

This study presents basic aspects of discrete asymmetrical pulses generated by using delay operator applied on certain dynamical system. It is shown that the asymmetry of position for significant values inside the pulse time interval can be modelled using a binomial written as {(a+b)}^n, with a≠b and a+b=1.
This binomial model proves useful when pulses become shorter each time when they pass through a certain material medium. In a previous study [1], a certain delay operator denoted as τ has been included in a binomial as (1+τ)^n. A certain dynamical system has been considered to start from an initial state S_i at zero-time moment. Describing the interaction generating pulses by an operator (1+τ)^n acting upon the initial state S_i of this system, it was shown that the corresponding time evolution of this system could be characterized by a state S determined through power n of this binomial applied upon the initial state. Connecting the coefficient multiplying power k of τ to a certain amplitude, a discrete-time function is generated which can be extended through interpolation in order to obtain a continuous function (easily to be represented graphically).
In another study [2] a graphical method for determining the parameters of this model based on tangent line in inflection point has been presented.
These previous studies are continued within this paper by extending the research upon asymmetrical pulses. It is shown how the point of maximum amplitude is shifted as related to the middle of the interval on which the pulse is defined as function of the difference a-b. The inflexion points k_{1,2}are determined for the case a≠b and the derivative of the pulse amplitude in these inflexion points (for a discrete function extended by continuity) is computed. It is shown that the derivatives in these points slightly differs to the value 2×Pulse Amplitude (the result previously obtained for symmetrical pulses) for great values of exponent n, but the difference becomes significant for lower values of n.
For a preliminary analysis of asymmetrical pulses, it is shown that from ratio k_{1,2}/n can be used for determining δ=(b-a)/2, and the difference D=k_2-k_1 can be further used for determining n. It must be mentioned that finally an optimization procedure should be performed (by searching the best possible values for a, b, n for validating the combinatorial model (the first approximation can yield for a, b, n values which differ to the real ones). An additional method based on a linear dependence of a Certain Response Time Constant when passing from a certain amplitude to the subsequent one is also presented. for justifying modelling supplementary asymmetries of derivatives (slopes) situated left/right as related to the point of maximum.
This asymmetrical binomial model provides a good extension for modelling pulses which time length varies when passing through active medium to the case when the symmetrical pattern of pulse amplitudes along the time axis is also altered.
This research was funded by the project: Advanced Infrastructure for Nuclear Photonics research experiments at ELI-NP / ELI-INFRA (Bucharest-Magurele).
[1] B. Dumitru and all, Scientific Bulletin Politehnica University, Bucharest, Series A-Applied Mathematics and Physics. 85 (1), 189 (2023)\
[2] C.Toma, Scientific Bulletin Politehnica University, Bucharest, Series A-Applied Mathematics and Physics, 86 (2), 147 (2024)

Speaker: Alexandru Toma (Honeywell Inc)

162 Overview on radiochemical purity control for 99mTc radiopharmaceuticals commonly used in nuclear medicine.

Most radiopharmaceuticals are used for the purpose of
medical diagnosis. These radiopharmaceuticals contain
small amount of the active substances with a
radionuclide attached to them to allow scintigraphic
imaging or measurement of biodistribution. Radiation is
a general property of all radiopharmaceuticals, which
when administered give the patient an imminent
radiation dose. Quality control (QC) tests are mandatory
for radioactive drugs which are intended for human
administration [1]. The safety and efficacy of
radiopharmaceuticals are important factor of the quality
assurance protocol. QA in radiopharmacy is critical for
practice. A poor-quality diagnostic radiopharmaceutical,
while not in itself unsafe, it could give incorrect
information about the patient’s condition leading to an
inappropriate choice of therapy [2]
In this study a considerable number of DMSA, PYP,
MAG-3, DTPA and HMPAO radiopharmaceuticals
samples are analyzed for their radiochemical purity using
radiochemical purity standard procedure. These products
used in nuclear medicine Department of University
Hospital Centre “Mother Theresa” and some private
clinics in Albania are collected and tested for 5 years
period. The aim of the work is to present the results for
their radiochemical purity and to emphasize the need for
the radiopharmaceutical quality control. The mean
radiochemical purity was 96.94% (standard deviation
7.82%) and 4.52% of all tested preparations failed to
meet radiochemical preparation limits.
Most radiopharmaceutical kits are prepared using

Speaker: Brunilda Daci (Institute of Applied Nuclear Physics, Albania)

Poster 2025-BPU-RF PDF.pdf

163 Searching for mirror neutrons and dark matter with cold neutron interferometry

We present a novel neutron interferometry scheme designed to probe the potential existence of mirror neutrons, which have been proposed as viable dark matter candidates. Our theoretical analysis shows that, if mirror neutrons exist, ordinary neutrons would acquire a detectable geometric phase due to their mixing with these mirror partners

Speaker: Gabriele Pisacane (University of Salerno and INFN)

164 The effect of spacetime torsion on neutrino mixing

Within the framework of quantum field theory, we investigate neutrino oscillations in the presence of a torsion background. Adopting the Einstein–Cartan theory, we analyze both the cases of constant torsion and torsion that varies linearly with time. We derive new neutrino oscillation formulae that depend on the spin orientation and obtain an expression for CP asymmetry.

Speaker: Simone Monda (University of Salerno and INFN)

165 Assessing the energy performance and decarbonization potential of hybrid nuclear-renewable energy systems

In this paper, we analyzed the environmental and economic impact of implementing a hybrid nuclear-renewable energy system in Romania, in order to support national decarbonization goals and contribute to the global energy transition. Using Romanian-specific generation data and energy supply/demand models we simulated a nuclear- solar/wind system. The simulations were conducted using the Nuclear–Solar/Wind Hybrid Energy System Part-Task Simulator developed by the International Atomic Energy Agency (IAEA). We analyzed the energy impact of such a system on the electricity grid and industrial processes in Romania, as well as possible integration challenges.We analyzed a nuclear-solar configuration combining a nuclear reactor with a Concentrated Solar Power (CSP) field. This system led to an increase in thermodynamic cycle efficiency from 34.6% to 38.1%, and a rise in net electrical output from 706 MWe to 837 MWe. These improvements highlight the value of the solar input for feedwater preheating or additional steam generation, achieved without altering the core thermodynamic structure of the plant. For the nuclear-wind configuration, we examined system behavior under varying wind speeds (0 m/s, 9 m/s, and 25 m/s). The results demonstrated the system’s operational flexibility, with the wind farm supplying up to 78% of the grid load at optimal wind conditions (25 m/s), allowing the nuclear reactor to operate in a reduced mode. Additionally, 213.99 MWe of surplus energy was utilized for hydrogen production. In the extended configuration, with the integration of a biomass processing plant, the hybrid system operated in a completely closed regime, where renewable and nuclear energy is converted into: biofuel, hydrogen and process heat. Thus, the ability of the proposed model to simultaneously meet electricity demand, produce unpolluted fuels and actively contribute to the circular economy was demonstrated. Our study demonstrates significant potential of hybrid nuclear-renewable systems to enhance energy efficiency, flexibility, and sustainability. By integrating solar and wind energy into a CANDU-based nuclear infrastructure, Romania can make substantial progress toward its decarbonization and energy transition objectives

Speaker: Sanda Voinea (University of Bucharest, Faculty of Physics, PO Box MG-11, Bucharest, Măgurele, Romania)

166 Digital Twins in Mechatronics: A Symmetry-Based Approach to System Modeling and Analysis

This paper explores the integration of symmetry principles into digital twin models for complex mechatronic systems, highlighting their potential to enhance modeling efficiency, anomaly detection, and system scalability. By leveraging structural and functional symmetries, the proposed approach supports modular system design, reduces computational overhead, and improves predictive maintenance capabilities. A comprehensive case study is presented, featuring a modular automated production line composed of a conveyor with 90 FIFO buffer positions, multiple CNC machining centers, and two 7-axis robots controlled via Siemens Sinumerik RunMyRobot/Direct Control. The simulation framework combines Software-in-the-Loop (SiL) and Model-in-the-Loop (MiL) methodologies, employing a CMVM digital twin of the CNC controller, Simit for communication simulation, and Mechatronic Concept Designer (MCD) for behavior modeling. Hierarchical physical and functional decomposition, aligned with Weiss and Qiao’s methodology, is applied to facilitate the development of a Component Mapping Matrix and to ensure simulation fidelity. The proposed approach demonstrates how incorporating symmetry and modularity in digital twins can accelerate deployment, enhance robustness, and improve decision-making in cyber-physical manufacturing environments.

Speaker: Nicu George Bîzdoacă (University of Craiova)

167 Modeling a Reactive Power Compensation System for Renewable-Based Grid Stabilization

The integration of renewable energy sources into isolated power systems presents significant challenges related to voltage stability and power quality. This study focuses on modeling a reactive power compensation system to stabilize a solar-powered grid in the isolated region of Crișan, Tulcea County, within the Danube Delta. Two simulation models were developed using MATLAB/Simulink: one employing capacitor banks and the other utilizing a Static VAR Compensator (SVC). The simulations incorporated both dynamic phasor and steady-state analysis methods. Results indicate that while capacitor banks offer a cost-effective solution for steady-state reactive power compensation, SVCs provide superior dynamic response and voltage regulation through real-time control using a PI regulator. The study concludes that a hybrid approach, combining both technologies, can enhance grid stability and ensure reliable integration of renewable energy sources in remote areas. This work underscores the importance of reactive power management in the transition to sustainable, emission-free energy systems.

Speaker: Sanda Voinea (University of Bucharest, Faculty of Physics, PO Box MG-11, Bucharest, Măgurele, Romania)

168 Optimizing Fourier ptychographic reconstruction for illumination wavelength and noise reduction

Microscopy is an important field that has seen significant improvements over the last decades to overcome unique inherent limitations. Some times the physical limitations could be overcome by using computational imaging. Fourier Ptychography is a powerful computational imaging technique that overcomes the resolution limitations of traditional microscopy by combining multiple low-resolution images captured under varied illumination angles. It overcomes the limitations of the traditional microscopes numerical aperture and reconstruct high-resolution image. The essence of this method lies in the reconstruction of images that go up to gigapixels using series of low-quality images. The traditional microscopic technique involves illumination by white light of the samples that are fixed on uniform glass slides. Here we test whether the Fourier Ptychography implemented on microscopic images acquired from a microfluidic chamber system depends on the wavelength of the illumination. We conclude that a shorter wavelength leads to a higher resolution of the images that are reconstructed. Results are combined with careful noise removal techniques involving different wavelets.

References
[1] Zheng, G., Horstmeyer, R., & Yang, C. (2013). Wide-field, high-resolution Fourier ptychographic microscopy. Nature photonics, 7(9), 739-745.
[2] Zheng, G., Shen, C., Jiang, S., Song, P., & Yang, C. (2021). Concept, implementations and applications of Fourier ptychography. Nature Reviews Physics, 3(3), 207-223.
[3] Uka, A., Imeraj, G., Qesaraku, B., & Shehu, B. (2022). Fourier Ptychography Microscopy Resolution Improvement Employing Refocusing. In BIODEVICES (pp. 191-195).

Speaker: Prof. Arban Uka (Epoka University)

BPU12_UKA_Fourier_Ptycho_Poster.pptx

Optimizing Fourier ptychographic reconstruction for illumination wavelength and noise reduction.docx

169 The Quantum Spectral-Model and Humphreys α-Multiplet Spectral Composition in H-I Spectrum

Starting from the quantum model of the hydrogen atom, we calculate and tabulate the peaks of Humphreys α-multiplet in fine-structure approximation (fs-approximation) [1,2]. We determine the spectral line peaks of this multiplet using a new MaximumLocalisation-spectral-Model which is based on several spectroscopic and statistical hypotheses [2-4]. By statistical analysis of the NIST and ACE data, we evaluate the parameters of the regression curves for the multiples of Lyman..Pfund and Humphreys spectral series (Fig.1). Furthermore, an algorithm for the quantum spectral reconstruction of multiplets in fs-approximation for any Sn spectral series of H-I is provided, n being the order of the spectral series. A plot representation is used to give a statistical global view of the first six series of H-I spectrum. The results confirm the measurements provided of the solar data from ACE mission [5].

Keywords: Humphreys series, solar data, NIST, spectral model, algorithm, statistics-regression.

Reference :

[1] A.E. Kramida, A critical compilation of experimental data on spectral lines and energy levels of hydrogen, deuterium, and tritium, Atomic Data and Nuclear Data Tables (2010).
[2] D. R. Constantin, L. Preda, M. Rushton, U.P.B. Sci. Bull. Series A 85-1, 167 (2023).
[3] D. R. Constantin, L. Preda, M. Rushton, U.P.B. Sci. Bull. Series A 85-4, 201 (2023).
[4] Marius Iosifescu et al., Mica enciclopedie de statistica, Ed. Stiintifica si Enciclopedica (1985).
[5] Frank Hase et al., Journal of Quantitative Spectroscopy & Radiative Transfer 111, 521 (2010).

Speaker: Dr Diana Rodica Radnef-Constantin (Institutul Astronomic al Academiei Romane)

titlu abs BalkanPhy25.pdf

EPS-TIG hands-on session “Frontier of Quantum Technologies”

Biophysics, Life Sciences, Medical Physics

170 Investigation of Customizable Radiation Shielding Materials: DLP 3D Printed Boron-doped Polymer Composites

Radiation shielding is essential to reduce the biological, technological and environmental risks associated with radiation exposure. Recently, Digital Light Processing (DLP) 3D printing has gained increasing attention as a flexible and rapidly expanding additive manufacturing technique, offering the capability to produce customized, lightweight protective components using UV-curable resins combined with high-resolution and functional additives. In this study, the potential of boron-rich polymer composites fabricated via DLP 3D printing as advanced radiation shielding materials was investigated.

Colemanite, a naturally occurring boron mineral, was doped into a photopolymer resin at concentrations of 0, 1, 2, and 5 wt% to enhance its radiation attenuation performance. Radiation shielding measurements of the colemanite-doped composites were performed against 356, 662, 1173, and 1333 keV gamma energies using a NaI(Tl) detector. The results demonstrated that increasing the colemanite content significantly improved gamma-ray absorption performance.

In addition to radiation shielding, the morphological and mechanical properties of the produced composites were examined through XRD, SEM, and EDX analyses. The findings revealed that colemanite-doped composites produced via DLP 3D printing exhibited effective radiation shielding performance, highlighting their potential for modern protective applications.

Speaker: Selami Eken (Kahramanmaraş Sütçü İmam University Faculty of Medicine)

2Investigation of Customizable Radiation Shielding.pdf

171 Insight from the analysis of the occupational exposure of personnel in the nuclear medicine department

This study focuses the retrospective analysis of the past 6 years of the occupational exposure at the Nuclear Medicine Department of the University Hospital Center “Mother Tereza” in Tirana (Albania). The effects of the relocation to a new building and the changes in the use of radiopharmaceuticals regarding radiological protection were analyzed. The personnel is monitored using chest badges equipped with TLD dosimeters, resulting in a total of 237 dose measurements. It was noted that the monitoring was not conducted systematically as expected by the legislation with a bimonthly cadence. The technicians and nurses were generally found to be the most exposed group of professionals, while occasionally the sanitary personnel received relatively high annual dose rates. Generally, the physicians received relatively low annual dose rates. The highest dose recorded was 1.32 mSv, reflecting a temporary increase of the use of radiopharmaceuticals due to the management of increased demand. Particular cases of minor incidents and their impact on the recorded dose were examined. There were no cases of an exceeded dose limits, with the highest annual dose found to be 2.2 mSv. Nevertheless, careful focus is essential to optimize workflow and workload allocation and ensure continuous training of the personnel in response to an increase of the procedures and changes in the radiopharmaceuticals utilized.

Speaker: Zeliha Muço (Department of Nuclear Medicine, University Hospital Center “Mother Teresa”, Tirana, Albania)

Abstract INSIGHTS FROM THE ANALYSIS OF THE OCCUPATIONAL EXPOSURE OF PERSONNEL IN THE NUCLEAR MEDICINE DEPARTMENT,Zeliha.Muco.doc

172 Enhanced Photophysics of Zinc Phthalocyanine Derivative by Conjugating to Noble Nanoparticles

Zinc phthalocyanine (ZnPc) derivatives have many interested
properties, such as high absorption capacity in the first
near-infrared region, good reactive oxygen species (ROS) generation
efficiency, and excellent photostability [1-3]. However, ZnPc are
highly hydrophobic and tend to aggregate, which decreases their
photosensitivity. Therefore, many attempts have been made to
increase the water solubility of phthalocyanine derivatives. The
simplest approach is to conjugate hydrophilic elements, such as
sulfo, carboxyl, amino, ammonium, hydroxy and as well as
polyethylene glycol groups at peripheral and non-peripheral
positions. Recent studies highlight the potential of ZnPc to be
combined with various nanoparticles, such as Ag, Au, or different
polymers, to enhance biodistribution and photodynamic activity [1].
In this study, zinc phthalocyanine was functionalized with chitosan
surface modified gold nanoparticles and were characterized using
UV-Vis absorption spectroscopy, X-ray diffraction (XRD), zeta
potential measurements, and dynamic light scattering (DLS). The
results demonstrated that the reaction temperature plays a crucial
role in controlling the size, shape, and crystalline structure of
the gold nanoparticles (GNPs). Moreover, it was shown that chitosan
can act as a scaffold for the assembly of GNPs, which were
successfully used for ZnPc functionalization. The first optical
indication of GNP formation was a visible color change over time,
from violet to light pink. This visible color arises from the
resonant interaction of light with GNPs via surface plasmon
excitation. Since the optical spectrum of GNPs strongly depends on
their size, shape, local environment, and electronic coupling, their
formation was monitored not only visually but more accurately
through UV-Vis extinction spectroscopy, showing a characteristic
absorption maximum at 520 nm. The zeta potential was approximately
–32.25 mV, and DLS analysis revealed a mean GNP diameter of
approximately 272.2 nm. All diffraction peaks could be attributed to
the (111), (200), (220), (311), and (222) planes of a face-centered
cubic (fcc) gold crystal. Also, photophysical parameters of
chitosan-functionalized noble nanoparticles conjugated with zinc
phthalocyanine derivative will be discussed.The UV-Vis absorption
spectra of ZnPc(COOH)₄ and ZnPc(COOH)₄:AuNPs structures showed a
well-defined B-band absorption maximum at around 364 nm and only a
slight attenuation for the Q-band of ZnPc(COOH)₄:AuNPs systems
compared to the pure ZnPc. Additionally, a minor red shift in the
characteristic Q-band-of ZnPc(COOH)₄ from 700 nm to 708 nm in
ZnPc(COOH)₄ AuNPs structures was observed.

Speaker: Dr Tamara Potlog (Moldova State University)

Abstract BPU 12 _Potlog.docx

173 Investigation of Gamma Radiation Absorption Parameters and Comfort Properties of Woven Fabrics with Hybrid Yarns Containing Haynes 25/L625 Alloy

The increasing use of X-rays and gamma rays in medical applications has heightened the demand for effective radiation shielding materials to mitigate the harmful effects of ionizing radiation. While traditional lead aprons are effective in providing radiation protection, their significant weight and inflexibility, coupled with the toxicity of lead, pose considerable health risks. This study investigates the potential of woven fabrics containing hybrid yarns made from Haynes 25/L625 alloy as a lightweight, flexible, and non-toxic alternative for gamma radiation shielding. The research focuses on the production of technical fabrics using hybrid yarns composed of Haynes 25/L625 alloy wires and recycled cotton/polyester blend yarns, woven in different patterns (3/1 twill, plain, and 5-harness satin), and evaluates their radiation absorption parameters and comfort properties.
The gamma radiation shielding properties of the fabrics were tested using a NaI(Tl) scintillation detector. The study measured key parameters, including transmission, absorption, linear attenuation coefficients, mass attenuation coefficients, half-value layer, tenth-value layer, mean free path, and radiation protection efficiency, across 15 gamma photon energies ranging from 32 to 1408 keV. The results revealed that the 5-harness satin weave fabric, which has the highest wire weight, exhibited the highest radiation absorption rates, particularly at lower energies, with a mass attenuation coefficient of 6.649 cm²/g at 32 keV. The 3/1 twill weave fabric, with moderate wire weight, demonstrated significant shielding effectiveness, especially at higher energies, achieving a linear attenuation coefficient of 0.291 cm-1 at 356 keV. In contrast, the plain-woven fabric with the lowest wire weight demonstrated the weakest radiation absorption performance among the three fabrics, with a half-value thickness of 1.106 cm at an energy level of 121 keV.
In addition to radiation shielding performance, the comfort properties of the fabrics, including air permeability, thermal behavior, and porosity, were also examined. Air permeability tests conducted in accordance with ISO 9237 standards showed that satin and twill weaves, characterized by floating yarns due to the low number of connections on the fabric surface, exhibit higher air permeability. In contrast, the plain weave, with its tightly woven structure, displayed the lowest air permeability. Thermal measurements, revealed that the plain weave fabric had the highest heat dissipation, while the twill weave exhibited the lowest. Microscopic porosity analysis further confirmed that the satin weave had the highest porosity (22%), followed by the twill (19%) and plain weaves (12%).
The findings show that the weaving type and the varying amount of Haynes 25/L625 alloy per unit area significantly affect both the fabric's radiation shielding performance and comfort properties. The 5-harness satin weave, with its high alloy amount and dense structure, provided superior radiation shielding, making it ideal for high-protection applications. The 3/1 twill weave offered a balanced combination of radiation protection and comfort, while the plain weave with the lowest amount of alloy demonstrated low breathability and high thermal diffusivity.
This study concludes that woven fabrics with Haynes 25/L625 alloy hybrid yarns offer a promising alternative to traditional lead aprons, offering radiation protection, reduced weight, and improved comfort.

Speaker: Dr Meryem Cansu Şahin (Vocational School of Health Services, Department of Medical Services and Techniques, Usak University, Usak, Turkey)

Abstract_MCS_BPU.docx

174 Virus like Particles: Core-controlled polymorphism and assembly mechanisms through titration

The T-number icosahedral configurations are considered to be given by a minimal mean-field thermodynamic model for the equilibrium structure of protein shells consisting of only pentamers and hexamers and correspond to the local free energy minima when the capsomers can switch freely between pentamer and hexamer.
Brome mosaic virus is one of the simplest and most thoroughly studied plant viruses. The capsid of BMV has a T=3 structure composed of 180 identical protein molecules which are clustered into hexamers and pentamers on the surface. The capsids diameter is about 28 nm and has an 18 nm inner cavity.
These capsids can be used for specific and localized treatment; therefore, it is important to study the thermodynamics of their assembling processes. Thus, GNPs whose diameter can be controlled from the synthesis were used as a cargo model.

Speaker: Anca Aldea (International Center for Advanced Training and Research in Physics (CIFRA), Magurele, Romania National Institute of Materials Physics (NIMP), Magurele, 077125, Romania)

175 Towards high sensitivity and low dose breast radiography with laser-driven X-ray sources

Interferometric X-ray imaging based on differential phase contrast offers greater sensitivity to soft tissue differences than conventional absorption-based radiography. This makes it a promising technique for the early detection of breast lesions, including those with minimal contrast, such as micro-calcifications. Additionally, since grating-based interferometry utilizes transmitted radiation and is effective at higher X-ray energies, where soft tissue becomes nearly transparent, it can enable a significant reduction in radiation dose. The grating interferometry method is the most clinically feasible form of X-ray phase imaging. However, current setups utilize interferometers about a meter long and relatively high radiation doses to produce clinical-quality images. We show that by extending the interferometer length to several meters and using gratings with micrometer-scale periods, the sensitivity of the system can be improved while further decreasing the dose. Such long interferometers need highly coherent and intense X-ray beams, which are beyond the capabilities of standard X-ray tubes. High-power (100-200-TW class) laser systems can meet these requirements by generating directional, bright X-rays through laser-plasma interactions. Finally, we introduce the Dr. LASER project at ELI-NP, which will develop a laser-driven X-ray source optimized for high-sensitivity, low-dose interferometric breast radiography, having the potential to improve breast cancer detection by combining advanced laser technology with X-ray interferometry.

Speaker: Nicoleta Safca (Extreme Light Infrastructure – Nuclear Physics, Bucharest-Magurele, Romania)

176 Phantom-Based Evaluation of Treatment Accuracy for Lung-like Targets in Ultrahypofractionated Stereotactic Treatments using Elekta Unity 1.5 T MR-Linac

Purpose
The integration of magnetic resonance imaging with linear accelerators (MR-Linac) has introduced a significant advancement in precision radiotherapy, especially for small field lung treatments where air-tissue interfaces present substantial dosimetric complexities. This study investigates the accuracy of dose calculation and delivery in ultrahypofractionated stereotactic body radiotherapy (SBRT) for lung-like targets using the Elekta Unity 1.5 T MR-Linac, supported by comprehensive phantom-based dosimetric evaluations.
Methods
Four identical spherical targets (1.5 cm in diameter) were placed within rectangular air cavities of a heterogeneous plastic water-equivalent phantom to simulate lung-like conditions. Two targets were placed at the center of the cavities and two were positioned at off-axis corners of the cavities adjacent to high-density phantom slabs. Each target was prescribed a mean dose of 650 cGy in a single fraction, with steep dose gradients beyond the target, reflecting ultrahypofractionated SBRT protocols. Treatment planning was performed using Monaco v6.2 with the GPU-based Monte Carlo Dose (GPUMCD) algorithm, employing eight equidistant isocentric coplanar beams and step-and-shoot intensity modulated radiotherapy (IMRT) delivery. Automatically segmented IMRT fields consisted of 4–20 segments with areas ranging from 0.279 to 9.975 cm² (mean: 3.124 cm²).
Dosimetric validation was conducted using a PTW microDiamond (MD) detector placed in a water-filled plastic phantom insert for direct dose measurements (five repetitions per target) and EBT4 Gafchromic films for entrance and exit dose verification. Measurement data were compared with GPUMCD calculations using mean percentage differences with standard deviations (MD detector) and gamma analysis with 3%/3 mm and 2%/2 mm criteria (EBT4 films).
Results
PTW microDiamond measurements demonstrated strong concordance with Monaco GPUMCD dose calculations. Off-axis targets yielded mean dose deviations of +1.2% ± 0.3% and −0.9% ± 0.2%, while central targets showed slightly greater, yet clinically acceptable, differences of +1.7% ± 0.6% and −1.8% ± 0.5%. EBT4 film-based gamma analysis demonstrated a minimum passing rate of 96.7% (3%/3 mm) and 94.6% (2%/2 mm) across all measured planes. Localized dose perturbations up to 4.2% were observed in regions immediately adjacent to air-tissue interfaces, consistent with the expected electron return effect (ERE).
Conclusions
This comprehensive dosimetric validation confirms that the GPUMCD algorithm delivers clinically acceptable dose calculation accuracy for small targets (≥1.5 cm) treated with small-field ultrahypofractionated protocols on the 1.5 T Elekta Unity MR-Linac. Target dose discrepancies remained below 2.5%, and gamma analysis consistently exceeded 94% pass rates, surpassing conventional clinical acceptance thresholds. The slightly higher deviations observed for centrally placed targets and at air-tissue interfaces highlight the necessity of meticulous treatment planning and robust quality assurance for anatomically complex regions. These results support the clinical feasibility of MR-guided SBRT for lung-like targets and establish baseline metrics to inform future quality assurance frameworks.
Keywords: MR-guided radiotherapy, MR-Linac, Small field dosimetry, EBT4 gafchromic film, Air-tissue interface

Speaker: Uğur AKBAYIRLI (Sakarya University of Applied Sciences)

Phantom-Based Evaluation of Treatment Accuracy for Lung-like Targets in Ultrahypofractionated Stereotactic Treatments using Elekta Unity 1.5 T MR-Linac.pdf

Condensed Matter, Materials and Applied Physics

177 Towards a better understanding of emergent materials

Emergent dynamics of solids has been the focus of research in condensed-matter physics for
the past decades. The interest is due to the fact that condensed-matter physics is expected
to serve both technological application and answer fundamental questions: On one hand, it
should provide guide lines for material design which implies that theory should give
quantitative microscopic predictions. On the other hand, the large number of interacting
degrees of freedom can lead to novel states of matter with unusual often enigmatic
properties whose characterization require the development of new concepts and methods.
In this talk, I will start with a historic overview. The main part will be devoted to materials
with heavy fermions. Since their discovery almost half a century ago, heavy fermion systems
have been a continuous source of surprising discoveries often challenging the theoretical
understanding at the time. While heavy fermion systems in their “normal” state can be
approximately described as Fermi liquids and therefore share common qualitative properties
it is important to emphasize that there are different routes to heavy fermions. The focus of
the present talk will be on intermetallic lanthanide (4f) and actinide (5f) compounds. I will
present results on the recently discovered compound CeRh2As2 [1] that exhibits a complex
phase diagram with rather unusual states at low temperatures. A prominent example is
multi-phase superconductivity which seems to develop inside a normal state involving by
itinerant multi-polar order [2]. The narrow quasiparticle bands arise from the Ce-4f degrees
of freedom via the Kondo effect. We conjecture that the Kondo-induced quasi-quartet CEF
ground state [3] in combination with pronounced nesting features of the Fermi surface [4,5]
may give rise to ordered states involving multipolar degrees of freedom [6]. Consequences
of topologically protected inter-band pairing in close analogy to UPt3 [7] will be discussed.
References
1. S. Khim et al., Science 373, 1012 (2021)
2. D. Hafner et al., Phys. Rev. X 12, 011023 (2022)
3. Denise S. Christovam et al., Phys. Rev. Lett. 132, 046401 (2024)
4. Yi Wu et al, Chinese Physics Letters (2024)
DOI 10.1088/0256-307x/41/9/097403
5. B. Chen et al., Phys. Rev. B 110, L041120 (2024)
6. P. Khanenko et al, arXiv:2409.11894
7. Z. Wang et al., Phys. Rev. B 96, 174511 (2017)

Speaker: Gertrud Zwicknagl (TU Braunschweig, Braunschweig, Germany)

178 Resonant and non-resonant transfers of Frenkel excitons in Helical DNA-like regular structures

Abstract. Frenkel excitons (FEs) as collectivized electronic excitations are studied using the models of two-strands regular structures with B-DNA geometry. As basic excitations we consider the excitations of the pairs of complementary bases, not the excitations of separate bases, because of the following reasons: 1. Permanent pairing of complementary bases A-T and C-G; 2. Small inter-bases distances. The following cases are treated:
A. Resonant transfer of FEs between equal pairs of complementary bases, e.g. A-T. The models of homopolymers are supposed to contain the equal pair at each step of double helix and one strand contains one base (A-A-A- ...) or alternatively ordered bases (A-T-A-T-…).
B. Non resonant transfer of FEs between different pairs AT↔CG. Two models are studied: a) two-step order sequence with bases in one strand A-C-A-C…; b) four-step order sequence in one strand A-C-T-G-A-C-…
The studied FEs originate from electronic excitations of the pair with transition electric dipole moment perpendicular to the helical axis (for π-π transitions) or parallel to the axis (for n-π transitions).
The corresponding Hamiltonians for each case allow to calculate the tensors of dielectric permittivity and gyration tensors, by using Green functions method (at temperature T=0). The calculations give formulas for excitonic spectra and the manifestation of FEs in linear absorption and in Circular Dichroism spectra.

Speaker: Ivan Lalov (Professor, Sofia University)

179 Some particularities of heat and oxygen transport in a 200mm Czochralski growth of silicon crystals

Nowadays Si-wafer based PV technology accounted for more than 95% of the total production. The market share of mono-crystalline technology is about 84% of total c-Si production. In order to meet the low-cost manufacturing criterion the Czochralski (CZ) crystal growth method which is the dominant technology for growing high quality monocrystalline silicon should be optimized. Defects and impurities incorporated in grown crystals during the growth process at the solid-liquid(S-L) interface limits the efficiency potential of the grown crystals because they reduce the minority carrier lifetime. The solar cell efficiencies achieved by the different techniques correlate directly with the material quality. Therefore, in order to increase the efficiency, a deep understanding of the underlying chemo-physical phenomena occurring during the crystallization process and their influence on the material properties is of utmost importance. Melt convection is acknowledged to be a very important factor in the field of crystal growth: Convective flows contribute to heat transfer and thus control the rate of solidification; The resulting temperature field in the vicinity of the S-L interface affects its shape and therefore the generation of thermal stress and the formation of dislocations; Convection controls the species transport in the melt; It affects the dissolution rate of crucible materials, It affects the formation and transport of particles in the melt; Furthermore, in a complex interaction of both heat and species transport, convection strongly influences the morphology and stability of the S-L interface. In a Cz process, time-fluctuations in temperature and in the concentration of impurities are mainly due to the melt convection with its two components: the natural convection and the forced convection generated by the rotation of the crystal and the crucible. In this contribution a numerical study using STHAMAS 3D software of the influence of different growth parameters (crucible and crystal rotations, pull rate) on the temperature and oxygen distribution will be presented for a 200mm Cz-configuration.

Speaker: Daniel Vizman (West University of Timisoara)

180 Molecular Dynamics Studies of Small Molecule Adsorption on Iron Oxide

High-temperature corrosion protection of low-alloy steel in steam generators of nuclear power plants is provided by a layer of magnetite. The presence of various small molecules in the cooling system affects the flow-assisted corrosion processes. The molecular dynamics (MD) method allows for an in-depth analysis of the mechanism and extent of adsorption of such molecules on magnetite at the molecular level. In the present work, a model surface {111} of magnetite with a layer thickness of 2.50 nm and a side length of 3.39 nm is constructed. The incorporation of such a complex system into MD simulation requires a modification in the imposed molecular mechanical force field (Clay FF). Two model systems consisting of a magnetite surface in the presence of an aqueous medium with ammonia or ethanolamine molecules are considered. MD calculations were performed in the NPT ensemble at a pressure of 90 bar using the TIP3P water model. For the two systems, different temperature ranges are simulated – for ammonia the temperature range is up to 473 K [1], for ethanolamine it is up to 503K. Data on the extent of adsorption have been obtained, the root mean square deviation (RMSD) of the target molecules has been calculated and their minimum distance to the magnetite surface has been traced. A comparison has been made with existing experimental results [2] and similar MD simulations.

References:
1 N. Ivanova, V. Karastoyanov, I. Betova, M. Bojinov, Molecules, 29, 3276 (2024).
2 M. Bojinov, I. Betova, N. Ivanova, V. Karastoyanov, Materials, 18, 944 (2025).

Acknowledgment: This study is funded by the European Union-NextGenerationEU, through the National Recovery and Resilience Plan of the Republic of Bulgaria, project № BG-RRP-2.004-0002 (BiOrgaMCT).

Speaker: Dr Nikoleta Ivanova (Department of Physical Chemistry, University of Chemical Technology and Metallurgy)

BPU 12 Congress_NIvanova.docx

181 An assessment of metal contamination in the Ishmi River sediments using XRF spectrometry

River sediments function as significant conduits and repositories for metallic materials originating from diverse sources, including agricultural treatments, industrial effluents, sewage discharge, and atmospheric deposition. In the presence of specific environmental conditions, the release of these metallic materials into the aquatic ecosystem can occur, thereby posing a risk of entry into the food chain and, consequently, endangering the health of organisms.
This study is based on a four-month monitoring of Ishmi river water quality, including the presence of microplastics and the presence of metallic materials. The geochemical status of the Ishmi River (Central Albania) sediments is hereby presented. The X-ray fluorescence (XRF) technique was employed to ascertain the concentrations of major and trace metallic elements.
In order to interpret the data, this study employed a multi-faceted approach. First, a quantitative analysis was performed using empirical coefficients. Second, an assessment of contamination was conducted using the Enrichment Factor (EF) and the Geoaccumulation Index (I_geo). Third, an analysis of elemental relationships using Pearson’s correlation coefficients was used. The results revealed significant enrichment of specific trace metals when normalized against the natural geological background.
The correlation analysis facilitated the differentiation between probable natural and anthropogenic sources of these pollutant elements in the Ishmi River, thereby offering a more nuanced understanding of the environmental pressures exerted on the river system.

Speaker: Ramadan Firanj (Institute of Applied Nuclear Physics, Albania)

High Energy, Particle Physics, Gravitation and Cosmology

182 W and Z production and properties

We present recent measurements of W and Z boson production using the CMS detector at the LHC at CERN. The production mechanisms of these processes are well understood within the Standard Model, and their high-precision measurements help confirm the fundamental principles of particle physics. Moreover, they serve as “standard candles” for probing other processes and for the search for signs of new physics. The results shown here are based on data collected during the Run 2 period.

Speaker: Itana Bubanja

IB_BPU.pdf

183 CMS High Level Trigger performance in LHC Run 2 and Run 3

The CMS experiment at CERN uses a two-level triggering system to select and store important events for physics. This system is made of the Level-1 (L1) stage, based on custom-designed electronics, and the High Level Trigger (HLT) stage, a sped-up version of the offline software reconstruction running on a computer farm. New trigger algorithms, coupled with advanced technological developments such as heterogeneous computing in GPUs and an optimized trigger menu at the HLT level, are essential to successfully record the events at higher data loads due to increasing luminosity and pileup at the LHC in Run 3. The performance of the CMS HLT during the entire Run 2 data-taking phase will be presented in this talk, together with the improvements and performance of this system in the ongoing LHC Run 3.

Speaker: Milos Dordevic on behalf of the CMS Collaboration (Vinca Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade)

BPU12 - CMS High Level Trigger in Run 2 and 3 - M. Dordevic.pdf

184 Optimal Control of Finite-Time Transformations in Black Hole Thermodynamics

We analyze optimal finite-time thermodynamic transformations in black hole spacetimes using geometric control theory. For Schwarzschild and Kerr black holes, we study protocols minimizing entropy production or energy cost under constraints set by thermodynamic metrics. We compare Hessian and Legendre-invariant thermodynamic geometries, focusing on their influence on thermodynamic length and process probability. Our results show how the choice of metric affects optimal paths and dissipation bounds in these systems.

Speaker: Tsvetan Vetsov (Sofia University "St. Kliment Ohridski")

185 A Two-Field Model for Cosmological Inflation

We study cosmological inflation with two real scalar fields. We start from one scalar field with the DBI-type Lagrangian, which is of non-canonical form This scalar field can be related to a perfect fluid which describes (dominant) matter in the Universe at a time of interest.

We then extend the model introducing auxiliary real scalar field. The second field does not carry any dynamics, i.e. the equation of motion (at the background level) for the first field will not change.

Finally, we promote the second field to be dynamical, adding its kinetic term. This model, with now two dynamical fields is used to study cosmological inflation. We discuss scalar cosmological perturbation and estimate the scalar spectral index for the two-field model.

References:
[1] D. Dimitrijevic, M. Dimitrijevic, G. Djordjevic, and M. Milosevic, AIP Conference Proceedings 2071, 020008 (2019).
[2] D. Langlois and S. Renaux-Petel, JCAP 0804, 017 (2008).
[3] C. M. Peterson and M. Tegmark, Physical Review D, 83(2):023522 (2011).

Speaker: Dragoljub Dimitrijević (Faculty of Sciences and Mathematics, University of Niš, Serbia)

Coffee Break

EPS-TIG hands-on session “Frontier of Quantum Technologies”

High Energy, Particle Physics, Gravitation and Cosmology

186 Overview of the 3D Si fast timing technology enabling 4D tracking under extreme radiation conditions and Multi-photon TCT as promissing 3D chatacterisation tool for spatialy resolved timing features

In this presentation we will briefly overview the most recent progress in the 3D Si technologies, developed within DRD3 (and RD50) CERN collaborations with emphasis on the 3D Si Double Side Double Type column technology. The presentation includes remarkable features of the multi-photon absorption transient current techniques used as 3D probing tool to spatially resolve the time of signal arrival. The potential of the Three-Photon Absorption - Transient Current Technique as a 3D Tomography of the radiation defects will be explored too. 3D Si devices may play a crucial role as timing technicity in HEP experiments enabling 4D tracking at future colliders.

Speaker: Gordana Lastovicka-Medin (University of Montenegro)

3Dsensors_GM_BPU12.pdf

187 Complete Theory of Simplicial Discrete Informational Spacetime: Towards a Predictive and Testable Theory of Quantum Spacetime

This paper introduces the Complete Theory of Simplicial Discrete Informational Spacetime. This meticulously constructed and self-contained theoretical framework is designed to address the profound challenges at the intersection of quantum mechanics and gravity. It offers a novel perspective on cosmology and the emergence of spacetime. The framework is rigorously developed and exhaustively defined, proposing a paradigm shift beyond the classical continuum to a fundamentally discrete and informational spacetime. At its core is the concept of simplicial chronotopes, indivisible quanta of spacetime and information, mathematically realized as regular 4-simplices. This work provides a complete and detailed exposition of the theory, from its primitive definitions rooted in Planck-scale quantization to its dynamical laws, emergent phenomena, and testable predictions. Crucially, the framework provides detailed derivations for key parameters, such as the Poisson ratio and spacetime stiffness, grounded in the symmetry and elastic response of the 4-simplex and linked to Planckian energy density and holographic entropy scaling. Through a synergistic combination of Non-commutative Geometry and Quantum Information Theory, the theory addresses the quantum-to-classical transition, singularity avoidance, and the emergence of classical gravity. It offers a mathematically rigorous and physically plausible pathway towards a predictive and testable theory of quantum spacetime and gravity

Speaker: Miltiadis Karazoupis (Independent Researcher)

Complete Theory of Simplicial Discrete Informational Spacetime.pptx

The Complete Theory of Simplicial Discrete Informational Spacetime BPU12 Review.pdf

The complete collection of papers of the SDIS theory

• Asymptotic Freedom in SU(3) Yang-Mills Theory within the Simplicial Discrete Informational Spacetime Framework.pdf
• Baryogenesis via Entropically Driven Asymmetric Network Stabilization in Simplicial Discrete Informational Spacetime.pdf
• Causal Structure in Simplicial Discrete Informational Spacetime.pdf
• Complete Theory of Simplicial Discrete Informational Spacetime.pdf
• Dark Matter as an Emergent Phenomenon in Simplicial Discrete Informational Spacetime.pdf
• Discrete Quantum Gravity with R2 Corrections.pdf
• Dynamic Self-Optimization of Simplicial Discrete Informational Spacetime and the Emergent Origin of the Speed of Light.pdf
• Emergence of Semi Dirac Quasiparticles in a Simplicial Discrete Informational Spacetime.pdf
• Existence of a Mass Gap in SU.pdf
• Fundamental Incompatibility of the Yang-Mills Mass Gap and Asymptotic Freedom within Continuum Quantum Field Theory.pdf
• Simplicial Complex and Monte Carlo Simulation.pdf
• The Emergence of the Standard Model from the First Principles of Simplicial Discrete Informational Spacetime.pdf
• The Simplicial Discrete Informational Spacetime.pdf
• Transient Wormhole Topologies in Simplicial Discrete Informational Spacetime.pdf

188 Physics potential for the measurement of Higgs to ZZ at FCC

Future electron-positron colliders can determine the absolute couplings of the Higgs boson to Standard Model particles in a model-independent manner and obtain a precise measurement of the Higgs boson’s decay width. Two key ingredients are the determination of the absolute Higgs to Z boson coupling, gHZZ, using the recoil method in the Higgsstrahlung Higgs production channel and the measurement of the Higgs decay to the pair of Z bosons in the same Higgs production mode.
The first results of the measurement of the Higgs to ZZ in Higgsstrahlung at the Future Circular Collider (FCC) are presented. We assume the nominal centre of mass energy, 240 GeV, unpolarized beams and integrated luminosity of 10.8 ab-1.

Speaker: Mila Pandurovic (Vinca Institute of Nuclear Sciences, Belgrade , Serbia)

HZZ_BPU12_MPandurovic.pdf

189 Recent results on Heavy-Ion physics from CMS

Heavy-ion collisions at the LHC provide valuable insights into the behavior of nuclear matter under extreme conditions. The heavy-ion program offers a wide set of measurements with the goal of studying different properties of the quark-gluon plasma. This presentation gives an overview of recent heavy-ion results from the CMS experiment. In addition, the prospects of CMS in heavy-ion physics, including upcoming data and detector upgrades, will be discussed.

Speaker: Jelena Mijuskovic

JMijuskovic_BPU2025.pdf

190 HyperScout-H: The Hyperspectral Imager for ESA - Hera Mission

The HyperScout-H (HS-H) instrument is one of the payloads aboard ESA's Hera spacecraft. Hera is a planetary defence mission that aims to provide detailed characterization of the near-Earth binary asteroid (65803) Didymos - Dimorphos following the NASA DART planed impact. HS-H is a dual-use payload that captures both images and spectral data within the 0.65–0.95 μm wavelength range. Observations from this instrument will offer key insights into the composition, space weathering effects, and the potential presence of exogenous material on the Didymos–Dimorphos system. Thanks to its wide field of view (15.5° × 8.3°), HS-H will be able to monitor the system’s orbital dynamics and dust environment, with both components of the binary asteroid remaining in the field of view for most of the asteroid phase of the mission.
The ESA Hera mission was launched on October 7, 2024, and is expected to arrive at its target by the end of 2026. During the commissioning phase, three days after launch, HyperScout-H obtained images of the Earth–Moon system. Later, during the Mars flyby (on March 12, 2025), additional images were acquired featuring Mars and its two moons. Calibration images are regularly scheduled throughout the cruise phase, prior to arrival at the asteroid.
In this talk, I will present the instrument’s functionality and discuss the images acquired during the in-flight phase.

Speaker: Marcel Popescu (University of Craiova)

Interdisciplinary Physics, Mathematical and Computational Methods

191 Spin 1 particle with two additional electromagnetic characteristics in presence of the both magnetic and electric fields

We study a generalized Duffin--Kemmer equation for spin 1 particle with two characteristics, anomalous magnetic moment and polarizability in presence of external uniform magnetic and electric fields.

After separating the variables in cylindrical coordinates, we get the system of ten first order partial differential equations for 10 functions $f_i(r,z)$. To describe the $r$-dependence of 10 functions $f_A(r,z), A=1,...,10$, we apply special method: the complete 10-component wave function is decomposed into the sum of three projective constituents, dependence of each constituent on the polar coordinate $r$ is determined by only one corresponding function, $F_{i}(r), i=1,2,3$; these three basic functions are constructed in terms of the confluent hypergeometric functions, there arises the quantization rule due to the presence of magnetic field.

After that we derive a system of 10 ordinary differential equations for 10 functions $f_A(z)$. This system is solved by using the elimination method and with the help of special linear combining of the involved functions.

As the result, we find three separated second order differential equations, their solutions are constructed in the terms of the confluent hypergeometric functions. Thus, the three types of solutions for a vector particle with two additional electromagnetic characteristics in presence of external uniform magnetic and electric fields are found.

Speaker: Alexander Chichurin (The John Paul II Catholic University of Lublin, Poland)

192 Linear Hamiltonians in generators of the Jacobi group GJ n(R) on the extended Siegel-Jacobi domain X˜J n

The energy function and the equations of motion on the extended
upper Siegel-Jacobi half space of order n attached to a linear Hamiltonians
in the generators of the real Jacobi group of order n are studied. The case
n = 1 is presented separately.

Speaker: Stefan Berceanu (IFIN-HH, Departmemnt of Theoretical Physics Bucharest)

Nuclear Physics, Energy Science and Technology, Accelerators and beams

193 Dipole response in neutron rich nuclei

This study investigates the dipole response of neutron rich nuclei with a focus on the role played by the symmetry energy, particularly its density dependence below saturation. Employing several theoretical approaches, linear response theory and the Migdal model, semiclassical simulations based on the Vlasov equation and Random Phase Approximation with separable interactions, we explore the evolution of dipole polarizability across the chain of nickel and tin isotopes as a function of symmetry energy parametrization with density. Our studies, by comparing with the experimental data, may provide additional constraints on the nuclear equation of state below saturation density.

Speaker: Cosmin-Marian Cipu-Drăghici (University of Bucharest)

194 High Entropy Alloys in Nuclear Applications: Radiation Shielding and Structural Integrity

Melisa Ozkan1, Baki Akkus 1, H.O. Tekin 2,3
1 Department of Physics, Faculty of Science, Istanbul University, 34134, Istanbul, Türkiye
2 Department of Medical Diagnostic Imaging, College of Health Sciences, University of Sharjah, 27272, Sharjah, United Arab Emirates
3Istinye University, Faculty of Engineering and Natural Sciences, Computer Engineering Department, Istanbul 34396, Türkiye

Abstract
Materials used in nuclear reactors must withstand harsh operating conditions such as high temperature, extreme radiation and mechanical stress. Conventional engineering materials tend to degrade under prolonged radiation exposure, directly affecting reactor safety and lifetime. In recent years, high entropy alloys (HEAs) have emerged as a revolutionary alternative in nuclear technologies due to their unique atomic structure and outstanding physical properties.
In this study, the radiation shielding capabilities and structural integrity of high-entropy alloys are investigated. In particular, the interactions, radiation-induced damage mechanisms and long-term stability of HEAs against neutron and gamma radiation are discussed. According to experimental and computational studies reported in the literature, high-entropy alloys (HEAs) demonstrate lower radiation-induced damage, higher mechanical strength, and superior thermal stability compared to conventional alloy systems.
A better understanding of the advantages of this new generation of materials in terms of radiation resistance is an important step for advanced reactor designs and safety standards.
Keywords: High Entropy Alloys; Nuclear applications; Radiation shielding

Speaker: Melisa Özkan (Istanbul University)

MELİSA ÖZKAN_ABSTRACT.rtf

195 Investigation of Radiation Absorption Behavior of Some Refractory High Entropy Alloys for Use in Nuclear Technology

In this study, a total of 13 refractory high-entropy alloys (HEAs) intended for use in nuclear technology were designed and their radiation shielding performances were systematically evaluated. The study focused on investigating the radiation attenuation characteristics of HEAs composed of refractory elements such as Zirconium, Tungsten, Niobium, Tantalum, and Molybdenum using PhyX/PSD software and MCNP simulation code. Among the designed compositions, the alloy coded ZrWNbTaMo₀.₄ demonstrated superior compatibility in terms of shielding parameters compared to the others. The findings of this research contribute valuable insights into the potential use of refractory HEAs in nuclear applications and present the ZrWNbTaMo₀.₄ alloy as a promising candidate, supporting its inclusion in the scientific literature.

Speaker: Gizem Öztürk (İstanbul University)

Physics Education, History and Philosophy of Physics

196 Balkans: Challenges and Perspectives in Secondary School Physics Education

Physics education across the Balkan region is confronted with persistent and complex challenges that affect both the quality of teaching and student engagement. Despite being a foundational discipline within the natural sciences, physics attracts a critically low number of students to pursue it further in higher education. In most Balkan countries, fewer than 10% of secondary school graduates go on to study physics or engineering at the university level. Of this small group, only 20–30% are female, reflecting a significant gender gap that continues to resist efforts toward greater inclusion in STEM (science, technology, engineering, and mathematics).
Several factors contribute to this disinterest in physics and broader STEM fields. High school physics curricula are often highly theoretical and disconnected from practical applications, making it difficult for students to see the relevance of the subject. Crucially, many Balkan education systems still lack interdisciplinary programs that integrate STEM disciplines, such as biophysics, bioengineering, or computational biology, missing opportunities to illustrate how science functions in todays interconnected world.
This disconnect has broader implications. The absence of modern, interdisciplinary content contributes to persistently low scores on international assessments like PISA, reflecting gaps not just in knowledge but in critical thinking and problem-solving. While technology initiatives like "One Laptop/Tablet per Child" are often discussed, they remain largely absent in practice—and even when devices are available, they are no substitute for quality educational content. As the saying goes, “the laptop/tablet is not the strength; it is the content that’s the strength.” Without investment in meaningful, integrated STEM curricula, like initiative Youth@STEM4SF [1] showcases, the region risks falling further behind in cultivating a scientifically literate and innovative next generation.
Outdated teaching methods, limited access to laboratory facilities, and insufficient teacher training compound the problem. Moreover, students often lack exposure to real-world applications and career opportunities in physics-related fields, especially within the regional context. The broader societal undervaluation of science professions, coupled with economic instability, further disincentivizes students from choosing STEM paths.
These challenges have broader implications. The outdated education systems in many Balkan countries limit innovation potential and hinder the development of STEM literacy among youth. Cross-border collaboration and networking opportunities for students interested in STEM are also rare. This is especially relevant in the Balkans, where scientific collaboration can support peacebuilding and regional cooperation. Projects like SEEIIST [2] - modeled after CERN and focused on cancer research—highlight the power of science diplomacy and multidisciplinary STEM synergy. By uniting experts from fields like physics, biology, engineering, and medicine, SEEIIST shows how breaking disciplinary boundaries can drive innovative solutions to urgent health challenges.
This paper outlines the current state of physics education in the Balkans and identifies systemic barriers within secondary STEM education. It argues for a coordinated, cross-national effort to modernize and strengthen science teaching, drawing on insights from both Balkan stakeholders and Swiss STEM education experts. The analysis is structured around several guiding questions that emerged from recent dialogues:
• What proportion of high school graduates pursue university studies in physics and engineering in each country, and what percentage of these students are female?
• What are the root causes of low student interest—are there identifiable gaps in high school science education?
• What methods and interventions have proven effective in raising interest, and how can they be better integrated into classrooms?
• What are the current trends and planned actions to embed sustainable development into science teaching?
• To what extent are physics-based industries involved in high school education, and how can these links be strengthened?
• What governance structures and stakeholders are needed to initiate and sustain reforms in science education across the Balkans?
By addressing these questions, the paper seeks to support policy innovation and foster collaborative regional responses that can shape a more inclusive and future-ready STEM education system in the Balkans - following international pioneering STEM education trends successfully piloted in other countries, such as Switzerland [1,3,4].

[1] B. Bruant Gulejova, Shaping high school science education with tech industry in action for sustainable development, Communications de la Société Suisse de Physique 73, 61 (2024);
https://www.sps.ch/articles/various_articles/
[2] SEEIIST – The South East European International Institute for Sustainable Technologies, https://seeiist.eu/
[3] Youth@STEM4SF (Youth at STEM for Sustainable Future) project, 2024 video: https://www.youtube.com/watch?v=uCvYcsR8qkE;
[4] B. Bruant Gulejova, Role of research and industry to attract future workforce, Europhysics News 56/2, May 2024, https://epn.eps.org/epn-56-2/#14

Speakers: Barbora Bruant Gulejova, Dr Konstantinos Vourlias (Aristotle University of Thessaloniki)

197 Bridging STEM, Sustainability, and Peacebuilding: Youth@STEM4SF from Swiss high school pilot towards Balkans

In response to declining student interest in physics and STEM fields, particularly among girls, the pioneering initiative Youth@STEM4SF (Youth at STEM for Sustainable Future) [1,2,3] developed with the international multidisciplinary community, was launched as Swiss pilot in 2023 under the auspices of the UNESCO International Year of Basic Sciences for Sustainable Development. Developed in partnership with the Swiss Physical Society (SPS), and Swiss educational authorities, Big Science Business community and other important partners, this innovative program introduces high school students to physics and STEM subjects through real-life applications, sustainability challenges, and encounters with inspiring role models from academia and industry.
During 2023-2024 the program has been successfully implemented in several Swiss schools reaching over 200 students from diverse schools and more than 100 Slovenian and Italian students through the pre-event of Big Science Business Forum in Trieste in 2024. It connects physics to pressing societal needs, such as climate change, energy, medical technologies, and environmental protection, by offering thematic days that include interactive talks and visits to tech industries and actors of innovation ecosystem; scaled up by student competition on the co-creation of new education materials connecting natural sciences with sustainable development. The most promising ideas from students are co-developed into digital teaching resources aligned with official education strategies. A majority of participating students, especially girls, reported a significantly increased interest in STEM fields, citing the visibility of relatable role models and societal relevance as key motivational factors.
This paper presents the outcomes of the Swiss pilot as a proof of concept and outlines a vision to expand the program to the Balkans during the UNESCO International Decade of Science for Sustainable Development (2024–2033) [4]. The project’s methodology – context based STEM teaching, connection to sustainable development and major societal challenges, modular thematic days, co-creation of teaching materials with target audience (students and teachers), digital user-friendly resources creation, teacher empowerment, multistakeholder collaboration and dive into the real innovation ecosystem (research and industry), gender equality in real action, capacity building for informed careers’ decisions - offers a scalable and adaptable model. Its application in the Balkan context seeks not only to raise STEM interest and appreciation, but also to promote regional peacebuilding, inspired by CERN’s model of international scientific collaboration and initiatives like SEEIIST [5], which is extremely relevant specifically in Balkan post-war countries. Therefore, the paper will discuss the program’s potential for cross-border engagement and science diplomacy.

By fostering a network of engaged students, teachers, scientists, and policymakers, Youth@STEM4SF aims to reform how STEM is taught and perceived. It strengthens links between science education and sustainable innovation ecosystems, helping to mitigate brain drain and build a new generation of informed, empowered leaders. This paper explores how this Swiss-born initiative can be adapted to support education reform, scientific literacy, and peace through science in the Balkan region and beyond, following the success of pioneering STEM education trends already successfully piloted in Switzerland, Slovenia and Italy.

[1] B. Bruant Gulejova, Shaping high school science education with tech industry in action for sustainable development, Communications de la Société Suisse de Physique 73, 61 (2024);
https://www.sps.ch/articles/various_articles/
[2] Youth@STEM4SF (Youth at STEM for Sustainable Future) project, 2024 video: https://www.youtube.com/watch?v=uCvYcsR8qkE;
[3] B. Bruant Gulejova, Role of research and industry to attract future workforce, Europhysics News 56/2, May 2024, https://epn.eps.org/epn-56-2/#14
[4] UNESCO International Decade of Sciences for Sustainable Development (2024-2033), www.un-sciences-decade.org
[5] SEEIIST – The South East European International Institute for Sustainable Technologies, https://seeiist.eu/

Speaker: Barbora Bruant Gulejova

198 The Relative Mechanical Motion and Inertiality - Bodies in Outer Space

The paper addresses the issue of mechanical representation of relative motions without direct reference to an inertial reference system. Even though classical mechanics states that it is not possible to find an inertial reference frame, relative measurements are used to determine the mechanical behaviour of celestial bodies with very small dimensions compared to the distances between them. This paper aims to demonstrate that the two fundamental theorems of mechanics, the momentum theorem and the angular momentum theorem, remain valid if we use only observations, measurements, and determinations of the distances, velocities, and relative accelerations between these celestial bodies along with the corresponding forces. The starting point for developing such a result is that the basic assumptions of Newtonian mechanics are considered to be valid and are used with the assumption that an inertial reference frame can exist, even if only hypothetically. In a first stage, the representation of relative motion was analysed using observations and measurements in an inertial frame. Then, in the next stage, relative motion was analysed using observations and measurements in a non-inertial reference frame that could be in a physical relationship with point bodies in relative motion.. Relationships are established between the relative accelerations and the corresponding global forces acting on each body in a two-body assembly, and the reduced mass is deduced as a physical quantity representing the inertia manifested in the relative motion. Based on this result, the other properties of relative motion are then expressed, including the two fundamental theorems of mechanics.

Keywords: inertial reference frames, inertiality in relative motions, equations of relative motion

Reference :
[1] Radnef Sorinn:tefan, The Relative Inertiality - The Relative Mechanical Movement of Bodies in Outer Space, INCAS Buletin, 17, 2 (2025).
[2] R. Voinea, D. Voiculescu, P. Simion, Introducere in Mecanica Solidului cu Aplicatii in Inginerie, Ed. Academiei Romane, (1989).
[3] G. W. Housner, D. E. Hudson, Applied Mechanics Dynamics, Division of Engineering California Institute of Technology, (1980).
[4] J. A. Shapiro, Classical Mechanics, (2010).
[5] M. M. Niță, Teoria Zborului Spațial, Ed. Academiei București, (1973).

Speaker: Dr Sorin Ștefan Radnef (INCAS-National Institute for Aerospace Research ”Elie Carafoli”)

Abstract_BalkanPhy25.pdf

199 A relativistic simulator in python

We present a 3D simulator developed using the Ursina Engine, inspired by sandbox-style games like Minecraft. The simulator incorporates core principles of special relativity—such as time dilation, length contraction, and the relativistic Doppler effect. It is designed as PoV game, in which
both the player and the surrounding objects can move; this allows phenomena as the Terrell rotation [1], [2] to be explained in an intuitive manner.

The main elements of theory which are illustrated in our simulator are presented in the documentation that accompanies code.

Our simulator can serve as an educational tool for university or high school students. The software is modular and designed for extensibility, allowing future integration of general relativistic effects, as well as elements from related fields like particle physics.

[1] Terrell, J. Invisibility of the Lorentz contraction. Phys. Rev. 116, 1041–1045 (1959).

[2] R. Penrose, The apparent shape of a relativistically moving sphere. Math. Proc. Camb. Philos. Soc. 55, 137–139 (1959).

Speaker: Maria Alexandra Boboaca (University of Bucharest)

200 Physics Education in Decline: A Two-Decade Mixed-Methods Investigation of Trends and Factors Influencing Albanian Students' Interest

Over the past two decades, Albania has seen a significant decline in interest in studying physics among primary and secondary school students. Physics, once considered a prestigious discipline, studied by the best and offering an intellectually rewarding career, is increasingly perceived by students as a tedious, highly abstract, and difficult subject that offers no prestige or income today. This declining trend, although it began much earlier, after the fall of communism, seems to have accelerated rapidly over the past two decades. This study undertakes a comprehensive mixed-methods analysis, integrating national quantitative data with qualitative findings from audits of curricula, physics textbooks, interviews with teachers and students, and policy reviews. The research identifies a series of interrelated causes: outdated curricula and inconsistent with the needs of the time and technological developments, poor textbooks on topics with incorrect linguistic and scientific terminology, a large shortage of qualified physics teachers - especially in rural areas - insufficient professional development and chronically insufficient investments in laboratory and school infrastructure, etc. The paper concludes by proposing a series of recommendations aimed at curricular reform, teacher support and learning infrastructure through experience and the implementation of projects related to actual real-world issues and technological developments, with the aim of restoring physics as a vital discipline in Albanian pre-university education.

Keywords: Physics, Pre-University Education, Students’ Engagement, Teaching and Learning

Speaker: Dr Inva Kociaj (Western Balkans University)

Physics Education in Decline - Presentation- Kociaj.pptx

201 Neutrons and Photons Elevating Worldwide Science (NEPHEWS) – Trans-National Access For Excellent Curiosity Driven Research

NEPHEWS – the Neutrons and Photons Elevating Worldwide Science – is an Horizon Europe Co-funded project-based access program targeting new and non-expert users and user communities, driven by the neutron and photon European user communities [1]. It delivers access to the world-class collective of Europe’s premiere open advanced neutron, synchrotron and free-electron laser complementary research infrastructures (RI), to promote curiosity driven excellence in research. The bottom-up User-to-User-oriented approach aims to build an integrated European RI landscape involving LEAPS [2] and LENS [3] consortia and their European scientific user communities. New and non-expert users receive in-depth hands-on expert training in twinning research experiments with expert-users, complimented with support in virtual access, workshops, schools and proposal writing. All build expertise, foster collaborations, and widen user access across the European Research Area. NEPHEWS specifically engages user and scientific communities of selected priority countries – of which Romania, Serbia and Greece are among those selected – via outreach visits, priority access, and supporting political dialogue of national user communities with national funding authorities. The simultaneous effort for neutrons, free electron lasers and synchrotrons across Europe reduces the access barrier for using these techniques, sustains the user communities and helps to provide knowledge transfer between the user communities, to industry and the wider society researchers of neutron and photon sources worldwide is provided. Specific reference and statistics of the participation by Romanian,Serbian and Greek researchers in worldwide neutron and photon facilities will be highlighted [4] along with opportunities for participation in NEPHEWS programmes for all Balkan researchers.

[1] NEPHEWS project webpage, https://beamtime.eu/
[2] LEAPS – the League of European Accelerator-based Photon Sources – https://www.leaps-initiative.eu/
[3] LENS – the League of Advanced European Neutron Sources – https://lens-initiative.org/
[4] Stankovski, M and Khotbehsara, F. A. P, “What is the size of the global light- and neutron source research communities?”, Lund Institute of Advanced Neutron and X-ray Science, May 2024, https://www.linxs.se/news/article-series-i/size-of-the-global-light-and-neutron-source-communities

Speaker: Cormac McGuinness (European Synchrotron and Free Electron Laser USer Organisation (ESUO) / Trinity College Dublin, Ireland)

Poster Session 4

202 INSEPARABLE TWO-QUBIT STATES via PHONON RESERVOIR

Here, we demonstrate the feasibilities to create inseparable quantum states among laser pumped pairs of two-level quantum dots embedded in a semiconductor substrate. The laser wave-vector is being normal to the line connecting the qubits, while the two-level emitters interact with both the environmental electromagnetic field reservoir as well as the phonon’s thermostat. Surprisingly, we have found that the entanglement between the qubit’s subsystem components significantly enhances due to the environmental phonon reservoir. This occurs because phonons open an additional decay channel that facilitates the entanglement creation [1].
Particularly, Figure 1 shows the concurrence C [2,3] which characterizes the entanglement among the qubit pair in the presence of phonons. Larger values for the concurrence are due to phonon population of the anti-symmetrical two-qubit cooperative state [1].

Speaker: Elena Cecoi (1Institute of Applied Physics, Moldova State University, Academiei str. 5, Chisinau, Moldova)

203 Quantum Reference frame and particle mixing

We examine the need for, and the emergence of, quantum reference frames in the context of defining a rest frame for mixed particles. We explore the related notion of frame-dependent entanglement and discuss its potential impact on measurements involving mixed mesons and neutrinos

Speaker: Antonio Capolupo (University of Salerno and INFN)

204 Rethinking WebQuests in the AI Era

In a physics classroom, students were given a classic WebQuest task designed to guide them through online research and reflection, using physics questions directly related to sustainable development principles, specifically solar cooking. The task aimed to examine the impact of modern technologies on students' curiosity and ability to explore curated resources and answer open-ended questions such as "What is your opinion about solar cookers?". However, instead of engaging with the provided materials, many 14–15-year-old students turned to ChatGPT for quick answers—effectively skipping over the thinking and research process entirely.
This experience highlighted a growing disconnect between traditional digital learning tools and the realities of today’s classroom. WebQuests, once innovative tools for structured online inquiry, were created for a very different internet—one based on fixed websites and static content. Now, with generative AI tools offering instant explanations and summaries, students can easily bypass the core of the WebQuest: the process of searching, evaluating, and synthesising information.
This poster explores the implications of this shift and suggests how WebQuests might be adapted for a world where AI is part of every student’s digital toolkit. It doesn’t argue that AI should be avoided—in fact, quite the opposite. If used thoughtfully, AI tools can support learning by offering feedback, sparking discussion, and expanding access to information. But to be effective, these tools need to be integrated into the learning design, not treated as threats or shortcuts.
We propose several adaptations to help bring WebQuests into the AI age:
- AI as a research partner: Students use AI to explain a concept (e.g. how a solar cooker works), then verify and critique the response using other sources.
- Prompt design challenges: Students compete to create prompts that get the most accurate or useful explanations from ChatGPT, and discuss what makes a good question.
- Peer teaching with AI: Students evaluate and improve an AI-generated explanation of solar energy for a younger audience, then present their version to classmates.
- Devil’s advocate arguments: Students ask ChatGPT to argue against using solar cookers, then write scientific rebuttals using both physical principles and societal arguments.
- Fact-checking AI: Students analyse an AI-generated text full of false or misleading claims, and work to correct the errors.
These activities emphasize process, not just product. Students are asked to reflect on their interaction with AI, explain how they arrived at their conclusions, and demonstrate that they understand the content—not just that they can reproduce it.
Alongside the opportunities, the poster also points out key challenges: students may overly rely on AI, lose opportunities for peer collaboration, or fail to develop critical thinking skills if the AI’s answers go unquestioned. There are concerns around academic integrity, misconceptions from AI errors, and reduced engagement if students feel AI can “do it better.”
Ultimately, this case study suggests that integrating AI into tools like WebQuests is not just a technical update—it’s a shift in how we think about learning. Teachers remain essential as guides, helping students use these new tools critically and creatively. If we can adapt our teaching to embrace AI without losing sight of the learning journey, we open the door to deeper engagement and more meaningful inquiry.

Speaker: Jana Bogdanoska (Ss. Cyril and Methodius University in Skopje)

205 Artificial Intelligence-assisted study of light diffraction: from observation to prediction

Abstract
This study presents new approaches to the phenomenon of light diffraction, combining traditional methods of physical investigation with modern Artificial Intelligence (AI) tools. The integration of AI in the study of wave optics allows an interdisciplinary approach that contributes to the development of STEM skills, stimulates scientific curiosity and gives the student the possibility to visualize, simulate and interpret complex phenomena with the help of digital technologies.
Keywords: Wave Optics, Light Diffraction, Artificial Intelligence.
‬‬
Reference:
[1] Rane, N., Choudhary, S., & Rane, J. (2023). Education 4.0 and 5.0: Integrating artificial intelligence (AI) for personalized and adaptive learning.
[2] Khonina, S. N., Kazanskiy, N. L., Efimov, A. R., Nikonorov, A. V., Oseledets, I. V., Skidanov, R. V., & Butt, M. A. (2024). A perspective on the artificial intelligence’s transformative role in advancing diffractive optics. iscience, 27(7).

Speaker: Gabriel Florian (1 Dolj County School Inspectorate, 200760, Craiova, Dolj, Romania 2 National High School “Carol I”, 200418, Craiova, Dolj, Romania)

Artificial Intelligence-assisted study of light diffraction_from observation to prediction.pdf

206 Atmospheric pressure DBD plasma source with flowing liquid films for degradation of antifungal drug traces from water

The widespread use of antifungal drugs, such as Nystatin, has contributed to the emergence of resistant Candida strains, posing a significant challenge to public health. The presence of antifungal residues in wastewater further exacerbates this issue, necessitating effective removal strategies. The atmospheric pressure plasma generates reactive oxygen and nitrogen species, which might interact with the antifungal compounds, leading to degradation and removal from aqueous solutions.
In this study we discuss the technical concept and preliminary rests on an atmospheric pressure DBD plasma source with flowing liquid film, as a solution for degradation of antifungal drug traces from water. The dielectric barrier discharge (DBD) plasma source is diagnosed using electrical and optical methods.
To evaluate the efficacy of Nystatin degradation in aqueous solutions of this method, UV-VIS spectroscopy was employed to monitor changes in Nystatin concentration before and after plasma exposure. The results demonstrated a significant reduction in the absorption spectra of Nystatin after treatment. These findings suggest that atmospheric pressure DBD plasma technology is a viable approach for the removal of antifungal drug residues from wastewater. This method could complement existing water treatment techniques, offering an environmentally friendly and efficient solution to mitigate the risks associated with pharmaceutical contamination. Future research should focus on optimizing treatment parameters, assessing potential byproducts, and evaluating the scalability of this plasma-based approach for large-scale wastewater treatment.

Speaker: Ionut Topala (Alexandru Ioan Cuza University of Iasi, Faculty of Physics)

207 DFT Parametrized Spin Hamiltonians for Simple Paramagnetic Molecules

This work will first present our results from the computational studies of the spin properties of selected paramagnetic molecular species, and then briefly study the combination of these results with analytical methods to compute the exact solutions of the studied systems. The molecular species we will work with are nitrogen monoxide and diboron, both of which are paramagnetic. First, Density Functional Theory (DFT) is used to evaluate parameters such as the $\mathbf{g}$-tensor values, including the diamagnetic correction, orbital Zeeman and spin-orbit coupling contributions. For this purpose, the Gaussian 09 software is used. Subsequently, a model Hamiltonian, specifically a spin Hamiltonian, which consists of the dominant magnetic interactions within the systems, is constructed. This Hamiltonian relies on the previously obtained parameters. The parametrized calculations of the diagonalized Spin Hamiltonian are performed using Wolfram Mathematica 11.

Speaker: Ljubica Dimova (Ss. Cyril and Methodius University in Skopje, Faculty of Natural Sciences and Mathematics)

208 Funding for Excellent Curiosity Driven Research via the Neutrons and Photons Elevating Worldwide Science (NEPHEWS) Trans-National Access Project

NEPHEWS – the Neutrons and Photons Elevating Worldwide Science – is an Horizon Europe Co-funded project-based access program targeting new and non-expert users and user communities, driven by the neutron and photon European user communities [1]. It delivers access to the world-class collective of Europe’s premiere open advanced neutron, synchrotron and free-electron laser complementary research infrastructures (RI), to promote curiosity driven excellence in research. The bottom-up User-to-User-oriented approach aims to build an integrated European RI landscape involving LEAPS [2] and LENS [3] consortia and their European scientific user communities. New and non-expert users receive in-depth hands-on expert training in twinning research experiments with expert-users, complimented with support in virtual access, workshops, schools and proposal writing. All build expertise, foster collaborations, and widen user access across the European Research Area. NEPHEWS specifically engages user and scientific communities of selected priority countries – of which Romania, Serbia and Greece are among those selected – via outreach visits, priority access, and supporting political dialogue of national user communities with national funding authorities. The simultaneous effort for neutrons, free electron lasers and synchrotrons across Europe reduces the access barrier for using these techniques, sustains the user communities and helps to provide knowledge transfer between the user communities, to industry and the wider society researchers of neutron and photon sources worldwide is provided. Specific reference and statistics of the participation by Romanian,Serbian and Greek researchers in worldwide neutron and photon facilities will be highlighted [4] along with opportunities for participation in NEPHEWS programmes for all Balkan researchers.

[1] NEPHEWS project webpage, https://beamtime.eu/
[2] LEAPS – the League of European Accelerator-based Photon Sources – https://www.leaps-initiative.eu/
[3] LENS – the League of Advanced European Neutron Sources – https://lens-initiative.org/
[4] Stankovski, M and Khotbehsara, F. A. P, “What is the size of the global light- and neutron source research communities?”, Lund Institute of Advanced Neutron and X-ray Science, May 2024, https://www.linxs.se/news/article-series-i/size-of-the-global-light-and-neutron-source-communities

Speaker: Cormac McGuinness (European Synchrotron and Free Electron Laser USer Organisation (ESUO) / Trinity College Dublin, Ireland)

209 Physics of soap films – inquiry problems for 12th grade of the Bulgarian school

Abstract: For centuries, soap bubbles have captured people's imagination. Bubbles have been entertainment, inspiration for paintings, an incentive for philosophers and poets to compare their short life to human life, and of course a huge challenge for scientists. Newton studied iridescent colors, Joseph Plateau proved the existence of a minimal two-dimensional surface with a given closed boundary, Lord Kelvin in 1887 searched for the arrangement of cells or bubbles with a minimal total surface area between them. According to him, one can dedicate their whole life to discovering physical laws just by blowing a soap bubble. Studying soap bubbles at school is useful from both theoretical and practical point of view. The report discusses the application of an inquiry approach to studying the topics of liquid properties and surface tension. The topic is studied in grade twelve of the profiled physics curriculum. Teaching takes place at several levels. Students are introduced to basic concepts, principles, and laws of fluids. A structured study is then conducted in which the surface tension coefficient is determined by several different methods. The properties of soap films obtained with different wire configurations are studied through guided investigation, in which students are presented with research questions, and they develop research procedures. The geometric and optical properties of two-dimensional membranes and the interaction between them are studied. From the two-dimensional membrane between soap bubbles, we move on to three-dimensional bubbles and the study of their properties. Advantages of the approach under consideration are the creation of interest and engagement of students, deepening of their mathematical knowledge, and the opportunity for interdisciplinary lessons in chemistry and art.
Keywords: inquiry approach, surface tension, surface energy, wave interference

Speaker: Daniela Ivanova

210 Pulse Envelope Forces in Linear Media: From Confinement to Collision Dynamics

The interaction of ultrashort femtosecond laser pulses with dielectric media reveals a new mechanism for trapping particles into the pulse envelope through a longitudinal optical force [1]. The effect is due to the linear and nonlinear polarization of the media and works for pulses with intensities, significantly below from the well-studied multiphoton and tunnel ionization regimes. Unlike tunnel ionization, which depends on high field amplitudes and low frequency, or multiphoton processes driven by nonlinear intensity scaling, the proposed collision-driven ionization regime is a result of kinetic energy accumulation due to this confinement. When the trapped particles reach sufficient density, the kinetic energy of the collision with ambient molecules in air is of order of 12-24 GeV and lead to ionization of the media for intensity of the pulse below than typical ionization thresholds. This presents a qualitatively new ionization regime, offering potential applications in directed particle acceleration and plasma generation, bridging the gap between linear optics and high-energy density physics. [1, 2]
In this work, we explore more precisely as the longitudinal radiation forces arising from the time derivative of the Poynting vector, depends from diffraction and dispersion of the optical pulse by solving analytically the 3D+1 paraxial equation in linear regime [3].

Speaker: Maria-Gabriela Zheleva (Georgi Nadjakov Institute of Solid State Physics, Sofia, Bulgaria)

Poster presentation_REV.docx

211 SMART PHONE USE IN A PHYSICS PROJECT ON MAGNETIC FIELD MEASUREMENTS

This paper presents a detailed teaching and experimental project on magnetism designed for high school students. The project aims to help students to measure magnetic fields using the “Phyphox” smartphone application and explore how magnetic field strength depends on various physical quantities such as distance, electric current, number of coil turns, and especially the size of the electromagnet core.

Speaker: Rilinda Doli (Albanian)

Tema dhe abstrakti R. Doli.doc

212 The contribution Hans Adolph Buchdahl f(R) gravity

Nenad Dj. Lazarov
Department of Theoretical Physics and Condensed Matter Physics (020), Institute of Nuclear Sciences Vinča-National Institute of the Republic of Serbia, University of Belgrade, P.O. Box 522, 11001 Belgrade, Serbia.

Email:lazarov@vinca.rs

ORCID ID Nenad Dj. Lazarov is: 0000-0003-3173-9636

Abstract. Hans Adolph Buchdahl was born in Mainz in German in a Jewish family. He was Australian Physicist and he was born 7 July 1919 and died 7 January 2010. He worked on general relativity, thermodynamics and optics. He was the founder of the modified theory of gravity of the f(R) type, where f(R) is general functions of Ricci scalar, unlike Einstain’s general theory of relativity f(R)=R. He proposed f(R) gravity first in in his paper 1970 [1]. He set up the field equations of f(R) gravity. Also he is known for developing Buchdahl’s theorem which is an relation between the mass and radius in the static, spherically symmetric matter configurations.
This paper will present his historical work on the creation of f(R) gravity as the founder of f(R) gravity, and also in one chapter it will be represented Buchdahl’s theorem.

[1] H. A. Buchdahl: Non linear langragians and cosmological theory. MNRAS 150 (1970),1(8).

Speaker: Dr Nenad Lazarov (Institute of Nuclear Sciences Vinca, University of Belgrade,)

abstract BPU 12 Nenad Dj. Lazarov S09.doc

The contribution Hans Adolph Buchdahl f(R) gravity A0 format Nenad Lazarov.pdf

The contribution Hans Adolph Buchdahl f(R) gravity A4 format Nenad lazarov.pdf

213 The Hubbard Model in Social Networks: Understanding Opinion Dynamics Through Many-Body Interactions

The Hubbard model, originally formulated to describe electron interactions in lattices, provides a powerful framework for understanding collective phenomena in complex systems. In this work, we adapt the Hubbard model to the study of social networks, drawing parallels between quantum many-body interactions and the dynamics of opinion formation, influence propagation, and polarization. The hopping term (t) represents the probability of individuals adopting or influencing opinions within their social connections, while the on-site interaction (U) models internal cognitive resistance to change. By incorporating external stimuli as driving forces, we explore phase transitions in social structures, such as consensus formation, polarization, and fragmentation. Furthermore, we investigate the impact of network topology—ranging from sparse, scale-free structures to fully connected networks—on the emergent collective behaviors. Using numerical simulations and analytical techniques, we analyze how variations in hopping strength and cognitive resistance influence stability and bifurcations in opinion dynamics. This adaptation offers insights into designing more effective interventions for mitigating polarization and enhancing information diffusion in social systems. The Hubbard model adaption provides a richer framework by including both local stability (U) and social dynamics (t), if we compare with other models that already have been investigating the behaviour of social systems.

Speaker: Klotilda Nikaj (University of Shkodra "Luigj Gurakuqi")

214 The Impact of Python Usage in the Teaching of Physics

The teaching of natural sciences in general, and physics in particular, has been transformed over the past decades under the influence of technology. The flexible working environments provided by programming languages have a considerable influence on the comprehension of Physics. This paper aims to demonstrate, through concrete results, the impact of using Python on improving the teaching-learning process of Physics for first-year students in Computer Engineering and Information Technology, whose curriculum includes Physics as part of their foundational education. The modeling and simulation of physical phenomena during exercise and laboratory sessions, using readily available and accessible GitHub repositories, contributed significantly to deepening conceptual understanding, increasing classroom participation and interaction, as well as enhancing students' analytical and technological skills-making Physics more accessible and relevant to their academic profiles.

Speaker: Dr Lorena Kelo ("Fan S. Noli" University, Korca, Albania)

215 THE INTERRELATION OF PHYSICS AND PHILOSOPHY: A DIALOGUE BETWEEN SCIENCE AND THOUGHT

This paper examines the profound and enduring relationship between physics and philosophy, a relationship that has shaped the trajectory of human inquiry from antiquity to the present day. By tracing their shared historical roots, the paper highlights how early philosophical speculation laid the foundation for scientific reasoning. Despite the modern institutional separation between the two disciplines, physics continues to grapple with questions that are fundamentally philosophical in nature, questions concerning the essence of time, space, causality, determinism, and the nature of reality itself. The study investigates the epistemological structures underpinning scientific knowledge, such as the criteria for theory confirmation and falsifiability, and explores the ontological assumptions embedded within classical and modern physics. Special attention is given to paradigm, shifting moments in the history of science, including the contributions of figures like Aristotle, Newton, Popper, and Kuhn, as well as the radical implications of quantum mechanics and general relativity. Through an analysis of contemporary debates, such as those surrounding the interpretation of quantum mechanics, the multiverse, and the conceptual validity of string theory, the paper argues that philosophy remains indispensable for critically examining and contextualizing scientific thought. Far from being outdated, philosophical reflection serves as a compass for navigating the conceptual challenges of theoretical physics. Ultimately, the dialogue between philosophy and physics is portrayed as a dynamic and reciprocal exchange, one that not only enriches both fields but is essential for advancing our understanding of the universe.

Speaker: Prof. Mara Scepanovic (University of Montenegro, Faculty of Natural sciences and Mathematics)

abstract_Mara_Scepanovic_BPU12.docx

216 EDUCATIONAL SOFTWARE FOR ASTRONOMICAL OBSERVATIONS

In recent years, it has become increasingly clear that national education is trying to find a favorable way to evolve, so that specialized institutions can provide the opportunity to carry out the educational process through consistent, modern, resonant methods, which want to be materialized. at the company level. The education system has many connections and interdependencies with the political and economic system of the state, which determines a wide range of influences, based on which education is in a perpetual process of change. Thus, it is very clear that, although there seems to be a desire for improvement, the optimal conditions for development must be created so that a synchronization between the steps of making proposals and the centralization of efforts results. Our country is showing interest in modernizing the educational information system and also has the ability to participate in wide competitions opened by European and international education systems.
This paper presents some educational aspects of the application of modern teaching methods, depending on the number of teaching hours, respectively the research practice, in the disciplines of Astronomy and Applied Informatics, from the point of view of Didactics. Both in our country and abroad, the effectiveness of these modern, computational teaching methods has been proven, as well as their importance, in adapting the new curriculum to the guidelines of modern international education. There are important differences between our education system and the European education system; For example, in our country, the competitive mentality is promoted, while in other European countries, students are recommended by the school or assigned to a new level of education.
In this paper is presented a software application, which through certain computational methods manages to systematically process information and return results from complex calculations based on data collected from the observations of cosmic bodies. This application has been designed as an illustrative site for how to manage the transfer and processing of astronomical observations of asteroids. Two areas are addressed, Educational Informatics and Astronomy, which may have many common areas of study. After applying research methods for students of the University of Craiova, from Computer Science specialization to Astronomy, we find that most mathematical models used in the study of astronomical phenomena have a solution by numerical means, based on the two fields being Mathematics. The Dutch computer scientist Edsger Dijkstra stated: "In Computer Science you are dealing with the computer, as you have in Telescope Astronomy", today the two tools have become just as important for those who practice in the field of Educational and Research Astronomy. Professional astronomers use both powerful telescopes and powerful computers. Astronomers first collect information using these tools, then analyze the information and then compare it with existing theories.

Speaker: Afrodita Liliana Boldea (National Institute for R&D in Physics and Nuclear Engineering, Magurele, Bucharest, Romania)

217 HANDS-ON EXPLORATION OF VIBRATIONS AND RESONANCE THROUGH MOBILE TECHNOLOGY

This paper presents a teaching experimental project on oscilations designed for physics students. The project aims to help students to study oscilations using the smartphone applications.
The smartphones, with their built-in sensors, are well-suited for use as reliable and versatile tools in simple educational experiments.
In this study, a smartphone is used to measure the vibration frequencies of rods with different lengths. The results obtained with the smartphone are compared with theoretical calculations and the agreement is good.
Another experiment is study of phenomenon of resonance with simple laboratory equipments. In this case, another smartphone’s application is used to measure the natural oscillations frequency of a system and the frequency of the forcing factor. Again, the results obtained are comparable to theoretical predictions and with a good level of agreement.
In this paper, special attention is paid to the use of the applications “Phyphox” and “Strobe light” and the benefits that students have.
The paper concludes with an evaluation from a pedagogical perspective and provides related recommendations.

Keywords: oscillations, smartphone, sensors, “Phyphox”, “Strobe Light”, experiment, active learning, autonomous work, resonance, frequency measurement, vibrations, frequency analysis

Speaker: Elsida Haxhiu

ABSTRACT Elsida Haxhiu, Albania.doc

218 The Future of Physics in the Age of Artificial Intelligence

The Future of Physics in the Age of Artificial Intelligence

This paper explores the evolving role of physics education in the context of rapid advancements in artificial intelligence (AI), with a particular focus on the current situation in Albania. Physics, as a fundamental science, remains crucial for understanding natural phenomena and driving technological innovation. The teaching of physics has undergone significant transformations over time — from classical lecture-based approaches to more interactive, experimental, and technology-enhanced methodologies. However, in Albania, the physics teaching profession faces serious challenges, including limited labor market analysis, difficulties in teacher integration due to ongoing education reforms, a prolonged qualification cycle, and relatively low salaries. These factors have contributed to a decline in student interest and a shortage of qualified physics teachers. Meanwhile, AI technologies offer promising tools to enhance teaching and learning, automate complex data analysis, and personalize educational experiences. This paper argues that while AI will transform physics education, it will not replace the essential role of human educators and researchers. Instead, a collaborative approach that leverages AI tools alongside skilled physics professionals is necessary to advance the discipline and improve educational outcomes in Albania and beyond.

Speaker: Klotilda Nikaj (University of Shkodra "Luigj Gurakuqi")

Friday 11 July

Condensed Matter, Materials and Applied Physics

219 An Overview of Groundwater Chemical Facies and Quality for Sustainable Water Resource Management in Albania

Groundwater is the lifeline of tap water for many cities in Albania, but its safety depends on regular assessments of its chemical quality. Pollution and overuse can silently affect its quality, putting both people’s health and the environment at risk. Safeguarding this essential resource aligns with SDG 6, which calls for the protection and sustainable management of water for current and future generations. This study aimed to investigate the chemical quality of the Lushnja aquifer by analyzing samples collected during the autumn 2010 campaign. The results presented in this paper highlight the unique hydrochemical facies of the Lushnja aquifer, which are crucial for the effective management and protection of this important water resource. Understanding the groundwater’s chemical facies is essential for assessing its suitability for drinking and irrigation, ensuring the well-being of the local population and the preservation of dependent ecosystems. This research also offers a clear picture of the groundwater’s drinkability in the Lushnja region—an important step toward smarter water management.
Different groundwater facies were identified. The dominant group mainly consists of bicarbonate-alkaline-earth waters, or more specifically, Mg-Ca-HCO₃ facies. A second group, is characterized by Ca-Mg-Cl⁻/SO₄²⁻ waters. Additionally, some samples exhibit with chemical characteristics of the Na-Cl facies, and finally, only few samples show a Na-HCO₃ facies.

Speaker: Dr Iris Bakiri (Institute of Applied Nuclear Physics, University of Tirana)

220 Low-Temperature Transport and Magnetoresistance in Bismuth Chalcogenide Topological Insulators

Bismuth/antimony-based chalcogenides such as $\mathrm{Bi_2Te_3}$, $\mathrm{BiSbTe_3}$, and $\mathrm{Sb_2Te_3}$ serve as prototypical compounds where the interplay of strong spin-orbit coupling$^[$$^1$$^]$ and crystal symmetry gives rise to both thermoelectric efficiency and topologically non-trivial surface states.$^[$$^2$$^]$$^[$$^3$$^]$ In this study, high-quality single crystals of these materials were synthesized via a modified Bridgman technique and comprehensively characterized using X-ray diffraction (XRD), SEM, TEM, and EDS.$^[$$^4$$^]$ Rietveld refinement of XRD data reveals a systematic variation in lattice parameters, with $a = b$ ranging from 4.27 $A^o$ in $\mathrm{Sb_2Te_3}$ to 4.38 $A^o$ in $\mathrm{Bi_2Te_3}$, and a corresponding unit cell volume expansion from 482.05 $A^o$$^3$ to 508.5 $A^o$$^3$, confirming successful isovalent doping and phase purity.

Temperature-dependent resistivity measurements ($4$K–$300$K) show metallic conduction in all samples, with clear Fermi liquid behavior below 50K. Fitting the low-temperature region to the expression $\rho = \rho_0 + AT^2$ yields coefficients $a$ ranging from 9.0 * $10^-$$^5$ to 20.5 * $10^-$$^5$ $\mu\Omega\cdot$cm/K$^2$, indicating enhanced electron-electron scattering in $\mathrm{Bi_2Te_3}$. Magnetoresistance (MR) measurements exhibit a prominent weak antilocalization (WAL) effect at low fields$^[$$^5$$^]$, which was quantitatively modeled using the Hikami–Larkin–Nagaoka (HLN) formalism. The $\alpha$ values, if around $-0.5$ to $-1$, confirm strong spin-orbit interaction with minimal magnetic scattering. Notably, $\mathrm{BiSbTe_3}$ displayed clear quantum oscillations resembling Shubnikov-de Haas behavior above 5T and a remarkably high MR of 140% at 2K and 9T, pointing to well-defined Fermi surfaces and high carrier mobility.

REFERENCES
[1] J. E. Moore, Nature 464, 194 (2010).
[2] L. Fu and C. L. Kane, Phys. Rev. B - Condens. Matter Mater. Phys. 76, 1 (2007).
[3] L. Fu, C. L. Kane, and E. J. Mele, Phys. Rev. Lett. 98,1 (2007).
[4] M. D. Anoop et al., Mater. Today Proc. 31, 616 (2019).
[5] H. K. Pal, V. I. Yudson, and D. L. Maslov, Phys. Rev.B Condens. Matter Mater. Phys. 85, 2 (2012).

Speaker: Ayush R. Mokashi (Department of Physics, Malaviya National Institute of Technology Jaipur (302017), India.)

221 Exciton Dynamics in I₂-Intercalated MoSe₂ crystals: Temperature-Dependent Luminescence and Kinetic Model

MoSe₂ layered crystals intercalated with iodine (MoSe₂:I₂) exhibit distinct photoluminescence (PL) due to excitons bound to the halogen molecules, which form neutral isoelectronic centers in the van der Waals gap [1]. At low temperatures, the luminescence is dominated by two sharp zero-phonon lines (ZPLs) labeled A and B at 1.036 and 1.042 eV, respectively, due to exciton recombination bound on iodine [2]. These lines, separated by Δ_AB = 5.6 meV are accompanied by a phonon sidebands.
With increasing temperature, a pronounced redistribution of intensity occurs between the A and B spectral components. Initially, the lower-energy A line dominates, but as temperature rises the higher-energy B line grows in intensity at the expense of A. This spectral evolution signifies thermally activated population exchange between the two exciton levels. Notably, the B state (higher energy) has a much faster radiative recombination rate (shorter lifetime) than the A state. Consequently, as thermal excitation promotes excitons from A to B state, the luminescence increasingly originates from the higher level.
Time-resolved measurements show that at low temperatures (T < 30K) the two-level exciton system is not in thermal equilibrium. The decay lifetimes of the A and B emissions differ by nearly a factor of two in this regime, indicating that the decay cannot be described by a single equilibrium lifetime. This nonequilibrium arises because inter-level exciton transfer is slow relative to radiative recombination at low T, owing to the sizable energy barrier Δ_AB. A kinetic model incorporating finite inter-level exchange is developed to account for this behaviour. By contrast, in previously studied halogen-intercalated TMDs with smaller Δ_AB, exciton populations remain near-equilibrium and a single radiative lifetime suffices to describe the decay. MoSe₂:I₂ thus exemplifies a process requiring an explicit two-level rate-equation model for exciton dynamics.
At higher temperatures (above ~60 K), the bound exciton PL intensity drops rapidly, with an activation energy of ~0.14 eV for this thermal quenching, that is attributed to thermally activated escape of the electrons from the I₂-bound state – an extrinsic self-trapping mechanism [3].
The developed kinetic model quantitatively reproduces the spectral and temporal characteristics of MoSe₂:I₂ exciton luminescence across the 10–150 K range. It captures the temperature-dependent A–B intensity ratio and the distinct A and B decay profiles, including the low-T non-equilibrium and high-T quenching behaviours. Our findings highlight that molecular intercalation can cause unique excitonic dynamics, and demonstrate the importance of including thermally activated population exchange in modeling exciton recombination in such two-level systems.

[1] A. Colev, et al, J. Luminescence, 129 (2009) 1945 and ref. therein.
[2] N. Siminel, et al., Optical Materials Express, 13, (2023) 887.
[3] M. Stavola, et al., Phys. Rev. B 30 (1984) 832

Speakers: Dr Nikita Siminel (Moldova State University, Institute of Applied Physics), Prof. Leonid Kulyuk (Moldova State University, Institute of Applied Physics)

Coffee Break

EPS - EIC Meeting

Closing Ceremony

14:00 Launch break

BPU Council Meeting

17:00 Farewell Dinner (only for the BPU representatives)

Saturday 12 July

Visit of the Parliament House (Optional)

Farewell Lunch