East European Journal of Physics

Reconstruction of Kaniadakis Holographic Dark Energy Model in Self Creation Theory of Gravity

Y. Aditya — 2025-03-03

The primary objective of this paper is to examine a Kaniadakis holographic dark energy universe of Bianchi type-II within the framework of self-creation gravity theory. In this dark energy model, the Hubble horizon is used as the infrared cutoff, following Kaniadakis' holographic dark energy concept. We calculate various dynamical parameters in this model, including the statefinder (r,s) plane, the deceleration parameter q, the equation of state (ω_de), the square speed of sound, and the ω_de-ω'_deprime plane. A graphical analysis of these parameters is provided across a range of free parameter values. The results reveal that the deceleration parameter demonstrates the universe's smooth transition from an early decelerated phase to the current accelerated expansion, while the equation of state parameter suggests a phantom phase. The ω_de-ω'_de plane reaches the thawing region, and the statefinder plane aligns with both the phantom model and Chaplygin gas. The current values of the parameters are consistent with existing observational data, and the strong energy conditions are found to be violated.

Accelerating the Cosmological Model with Zero-Mass Scalar Field in Lyra’s Geometry

R. Santhikumar — 2025-03-03

Examining Bianchi's type-III cosmological model involves incorporating a zero-mass scalar field in the context of Lyra's geometry. The source of energy-momentum tensor is supposed to be a bulk viscous fluid. A barotropic equation of state is applied to characterize the Pressure and density, seeking a specific solution to the field equations. This solution is derived using the distinctive variation principle for Hubble's parameter proposed by [M.S. Berman, Il Nuovo Cimento B, 74, 182 (1983)]. The ensuing analysis delves into the physical properties inherent in this model.

FLRW Cosmological Model with Quadratic Functional Form in f(R, T) Theory of Gravity

Chandra Rekha Mahanta — 2025-03-03

This work investigates a spatially homogeneous and isotropic flat Friedmann-Lemaître-Robertson-Walker (FLRW) universe within the context of f(R, T) gravity as introduced by Harko et al., [Phys. Rev. D, 84, 024020 (2011)]. The present work deals with the functional form f(R, T) = f₁(R) + f₂(T) with f₁(R) = R + λ₁R₂ and f₂(T) = 2λ₂T where λ₁ and λ₂ are arbitrary constants, R and T being the Ricci scalar and the trace of the stress-energy tensor T_ij respectively. We present a novel cosmological model in the framework of f(R, T) gravity, exploring the dynamics of the FLRW universe through an exact solution to the gravitational field equations. By employing an innovative ansatz for the Hubble parameter, H = α (1 + 1/t) where α is a positive constant, we capture a evolutionary history of the universe. This approach provides a natural pathway to investigate key cosmological parameters, such as the scale factor, deceleration parameter, jerk, snap, lerk parameters and energy conditions, revealing intriguing insights into the universe’s expansion dynamics. We also discuss the statefinder diagnostic. Our results offer a deeper understanding of cosmic evolution within the f(R, T) gravity framework.

Thermodynamics of Homogeneous and Isotropic Universe for Various Dark Energy Conditions

Neeru Goyal — 2025-03-03

The thermodynamic properties of homogeneous and isotropic universe for various dark energy conditions with decaying cosmological term Λ(t) are investigated. To obtain the explicit solution of Einstein’s field equations, we have considered a linearly varying deceleration parameter in the form of q =-αt + m - 1 with α and m as scalar constants. We have constrained the model parameters H₀ and m as 68.495 km/s/Mpc and 1.591 respectively by bounding the derived model with combined pantheon compilation of SN Ia and H(z) data sets. Furthermore, we have studied the time varying dark energy states for two different assumptions i) Λ = Λ₁t^-2 and ii) Λ ꭀ [R(t)]⁻²ⁿ. For a specific assumption, our models indicate a dark energy like behaviour in in open, flat and closed space - time geometry. The temperature and entropy density of the model remain positive for both the cases i) Λ = Λ₁t^-2 and ii) Λ ꭀ [R(t)]⁻²ⁿ. Some physical properties of the universe are also discussed.

Bianchi Type VI0 Generalized Ghost Pilgrims Dark Energy Cosmological Model in Saez-Ballester Theory of Gravitation

Tenneti Ramprasad — 2025-03-03

The Generalized Ghost Pilgrim Dark Energy (GGPDE) in the Saez-Ballester Theory of Gravitation (SBTG) and the Bianchi type VI₀ space-time framework serve as the foundation for this work. We used Mishra and Dua's [Astrophys. Space Sci. 366, 6 (2021)] straightforward parameterization of average scale factor a(t) = exp{(αt+β)^p} to find precise solutions to the field equations. We have looked into the GGPDE and dark matter (DM), both when they interact and when they don't. For both models, some significant and well-known parameters are produced, including the Hubble parameter, the equation of state (EOS) parameter, the deceleration parameter, etc. It is discovered that for both models, the deceleration parameter denotes an accelerated phase and the EOS parameter a cosmological constant. For both the non-interacting and interacting models, the stability analysis and energy conditions are examined.

Dynamics of String Cosmological Model in f(R,Lm) Theory of Gravity

S.D. Katore — 2025-03-03

The present paper examines the FLRW model with cosmic string within the framework of f(R, L_m) gravity, considering two different forms of f(R, L_m) gravity such as f(R, L_m) = R/2 + L^η_m + β and f(R, L_m) = Λe^{[(R/2Λ)+(Lm/Λ)]}, where η, β and Λ are free model parameters. The solutions of the models are obtained using both, the power law and the hybrid expansion law. The resulting physical and dynamical parameters of the models analyzed and presented through graphical representations.

The Eigen ICRF signals localized at Alfven resonances in a tokamak low-density scrape-off layer

Oleksandr Trush — 2025-03-03

Abstract – Eigen electromagnetic waves with small toroidal wave indices and positive poloidal wave indices are considered in the Ion Cyclotron Range of Frequencies (ICRF) in a tokamak Scrape-Off Layer (SOL). The waves are shown theoretically to exist in the form of the signals localized at the local Alfven Resonances (ARs). The evanescent regions in the direction of lower plasma density are provided by the presence of the wave nonzero poloidal wave indices. The narrow evanescent regions in the direction of higher plasma density are caused by strong plasma variation. The latter regions separate ARs from the high-density SOL and plasma core which are propagating regions for ICRF waves. The dispersion relation of ICRF signals is derived analytically and solved numerically. Possible relevance of the obtained results to experimental measurements is discussed. An exhaustive definition of the signals’ excitation sources is out of scope of the present study.

Generation of Electromagnetic Ion Cyclotron Wave by Hot Injection of Ion Beam for Ring Distribution with A.C. Electric Field in Jovian Magnetosphere

Garima Yadav — 2025-03-03

This paper investigates the electromagnetic ion-cyclotron waves detected by the Ulysses spacecraft within the Jovian magnetosphere. Various types of high-frequency radio emissions resulting from resonant interactions have been identified in this region. The study focuses on the wave-particle interactions between electromagnetic ion-cyclotron waves and fully ionized magnetospheric plasma particles, considering the parallel propagation of these waves. This allows for a detailed evaluation of the dispersion relation with a ring distribution in the presence of a parallel alternating current (AC) electric field within a collisionless magnetosphere of Jupiter. Using a method of characteristics and a kinetic approach, we derive an expression for the relativistic growth rate. Additionally, we analyze injection events recorded by the Galileo spacecraft through its energetic particle detector (EPD) in the Jovian magnetosphere. Following the injection of a hot ion beam, we conduct a parametric analysis of various plasma parameters, such as temperature anisotropy, AC frequency, and relativistic factors, to examine their effects on the growth rate, which is illustrated through plotted graphs.

Influence of Thermal Radiation on MHD Casson Nanofluid Flow over a Non-Linear Stretching Sheet with the Presence of Chemical Reaction

P. Raja Shekar — 2025-03-03

The focus of this research is to examine how the Casson and chemical reaction parameter impact the variable radiative flow of MHD Nanofluid across a stretching sheet. Through the use of similarity functions, the modelling equations (PDEs) of the motion of fluid are transformed into simple differential equations. The MATLAB tool is adopted to compute the equations numerically. Graphs and descriptions have been provided for velocity, concentration, and temperature outlines, showing the effects of important fluid flow constraints. Different factors are analysed to provide data and explanations for Prandtl, Lewis numbers, slip and chemical decomposition parameters. The current results are in good in good align with existed reports. The viscosity of the fluid and thermal boundary stratum decreases as enhancing of Casson, Magnetic parameter & Prandtl number. Skin friction increasing as enhancing of suction, stretching, magnetic and Casson parameter while decreasing as enhancing of velocity slip quantity. Rate of heat transmission enhancing as increment of thermal radiation and surface temperature while decreasing as enhancing chemical reaction and thermal slip quantities. Rate of mass transfer raising as enhancing of chemical reaction, thermal slip, thermal radiation while decreasing as enhancing of surface temperature parameter.

Effects of Hall Current on Darcy-Forchheimer MHD Mixed Convective Flow Over a Vertical Surface with Rotation in Porous Medium

Satyabhushan Roy — 2025-03-03

The analysis of Darcy-Forchheimer MHD flow has been a concern of consideration for research scientists and engineers. This work examines the unsteady hydrodynamic mixed convective flow of an incompressible, viscous, electrically conducting fluid as well as the transfer of heat and mass in a vertical surface with the Hall current, rotation, and Darcy-Forchheimer effect. Through similarity transformation, the dimensionless unstable governing equation's exact solution is found. Then, using the Matlab method Bvp4c, the similarity ordinary differential equation was solved. When the exact solution and those produced by Elgazery and Stanford were compared to the numerical result for a few exceptional circumstances, there was a fair degree of agreement. Graphs are used to show the temperature, concentration, and fluid velocity. In contrast, skin friction, the Sherwood number, and the Nusselt number are calculated in tabular form.

Biomagneto-Hydrodynamic Williamson Fluid Flow and Heat Transfer Over a Stretching Surface: A Spectral Quasi-Linearization Approach

Kairavadi Suresh Babu — 2025-03-03

The flow and heat transfer of a Williamson fluid subjected to a magnetic field are analyzed and investigated through the spectral quasilinearization method (SQLM). The equations concerned with momentum and energy are obtained from the Navier-Stokes equations, accounting for non-Newtonian effects, viscous dissipation, magnetic forces, and the Lorentz force. The electrically conductive fluid’s interaction with the magnetic field produces the Lorentz force, which strongly modifies flow behaviour by exerting a resistive force against the fluid’s velocity. The method efficiently linearises the non-linear equations, enabling accurate solutions through the spectral method. Numerical results highlight the influence of Williamson fluid parameters, magnetic field intensity, and heat sources on velocity and temperature fields, offering insights into the fluid’s behaviour in industrial applications involving non-Newtonian fluids and magnetic fields.

Numerical Investigation of Joule Heating Effect on Micropolar Nanofluid Flow Over an Inclined Surface in Presence of Heat Source

Keshab Borah — 2025-03-03

The MHD boundary layer flow of a micropolar nanofluid across an inclined stretching surface in the presence of a heat source is examined in this paper. This study employs permeable inclined surfaces with energy flow as its primary observation with heat radiation and the Dufour impact. The impact of Joule heating, viscous dissipation and heat source on the porous media are also considered. This study uses similarity transformations to convert nonlinear partial differential equations that governs the flow to ordinary differential equations. The bvp4c computational technique in MATLAB is used to illustrate the numerical findings. Based on the findings we were able to determine that the velocity and angular velocity of the fluid increases with the angle of inclination, the temperature profile increases with the increasing values of Eckert number whereas the concentration profile decreases with Eckert number. These findings are further illustrated through numerical data presented in table and visual representations in figures. These findings will enable engineers and scientists to better control fluid flow, leading to improvements in complex systems that rely on it.

Performance Enhancement of InGaP/GaAs Dual-Junction Solar Cells Through BSF Layer Optimization and Hetero-Tunnel Junction

Ikram Zidani — 2025-03-03

This study focuses on the simulation and optimization of an InGaP/GaAs dual-junction solar cells using Silvaco Atlas software, with a special emphasis on the incorporation of a hetero tunnel junction. The hetero-tunnel junction plays a pivotal role in enabling efficient charge carrier transport between the sub-cells, significantly improving the overall cell efficiency. Additionally, a new back-surface field (BSF) layer was integrated into the GaAs bottom sub-cell to further enhance performance. Various material combinations for the hetero-tunnel junction such as GaInP/GaAs, AlGaInP/GaInP, and AlGaInP/GaAs were systematically tested to assess their influence on device efficiency. The optimized structure demonstrated a short-circuit current density of 1.780 mA/cm², an open-circuit voltage of 2.310 V, a fill factor of 86.501%, and a conversion efficiency of 35.57% under AM1.5G illumination at 300 K. Recombination losses were minimized by the BSF layer optimization in the top and bottom cell, particularly with AlGaInP, leading to improved charge collection. Elevated temperatures were found to reduce both the open-circuit voltage and efficiency, highlighting the necessity of thermal management. These optimizations represent significant improvements over prior designs.

Optimization of Organic Photodetectors Using SCAPS-1D Simulation: Enhancing Performance of PBDB-T-2F Based Devices Through Layer Configuration and Doping Adjustments

Ahmet Sait Alali — 2025-03-03

In this study, we conducted an exploration of the optimization of various parameters of a photodetector using SCAPS-1D simulation to enhance its overall performance. The photodetector structure was modified based on the structure proposed by N.I.M. Ibrahim et al. (AMPC, 14(04), 55–65 (2024) by changing the order of the hole transport layer (HTL) and electron transport layer (ETL). Through the optimization of layer thicknesses and doping concentrations, we significantly improved the photovoltaic parameters of our optimized structure (FTO/PFN/PBDB-T-2F/PEDOT/Ag). The optimized device exhibited V_OC of 1.02V, J_SC of 35.20 mA/cm², FF of 84.61%, and an overall efficiency of 30.40%. Additionally, the device demonstrated a high quantum efficiency (EQ) of over 99% and responsivity peaking at 0.65 A/W, covering a broad spectral region from 300 nm to 900 nm. The results indicate the critical role of meticulous optimization in developing high-performance photodetectors, providing valuable insights into the design and fabrication of devices with superior performance characteristics.

Effect of the Porosity of a PSi Substrate on the Characteristics of CdS Nanoparticles Produced by the CBD Method

F. Saker — 2025-03-03

The motivation for research to study the potential offered by semiconductor materials such as silicon is their use as a substrate for the manufacture of thin films. In this work the chemical bath deposition (CBD) method was used to synthesize Cadmium sulphide (CdS) thin films on glass, silicon (Si), and porous silicon (PSi) substrates. The PSi substrates were prepared by an electrochemical etching method using different current densities at constant etching time of 5 minutes. The obtained results demonstrated that the morphology of the deposited materials was influenced by the porosity of the PSi substrates. The average crystallite dimensions for CdS/glass and CdS/Si were determined to be 46.12 nm and 23.08 nm, respectively. In CdS/PSi structures, the average value of the grain size decreases with increasing porosity. The smallest one is obtained for the CdS/PSi structure with 70% porosity, amounting to 11.55 nm. The measured current-voltage characteristics in coplanar structure on the CdS/PSi/Si sample showed that the photocurrent of the CdS/Si structure is of 3.17 µA and increases up to 600 µA for the CdS/PSi/60% structure.

Fast and Cheap Synthesis of CuO/ZnO Thin Films Made with The Spray Pyrolysis Technique

Y. Bellal — 2025-03-03

In this paper, CuO/ZnO nanocomposites thin films were elaborated with different combination ratio of precursors (copper chloride, zinc chloride) dissolved in distilled water using the spray pyrolysis method in order to study their physicochemical properties. Nanocomposites were elaborated as thin films deposited on the surface of ordinary glass at 550°C using a cheaper and fast technique. Optical, structural and morphological properties of the latter have been examined by UV-vis, X-ray diffraction (XRD), RAMAN, SEM/EDS and AFM. XRD peaks prove the attendance of the polycrystalline models of CuO and ZnO with preferential orientation. Raman shift spectrum confirms the attendance of CuO and ZnO nanocomposites. SEM/EDS and AFM support that there is same roughness on the surface of the ordinary glass RMS=106 nm, which is suitable for the mechanism of photodegradation. In the visible region, we notice a high absorbance and high optical band gaps (Egap= 4.07 eV) that is suitable for the photodegradation of undesirable substances.

Impact of Resistivity on Electrical Characteristics of Al-Doped ZnO/p Si Heterostructures

Fakhriddin T. Yusupov — 2025-03-03

This study investigates the impact of the resistivity of Aluminum-doped Zinc Oxide (AZO) films on the electrical characteristics of AZO/p-Si heterojunctions. AZO films were deposited using a thermal evaporation technique on p-Si substrates, with varying deposition temperatures to control film morphology and resistivity. Comprehensive current-voltage (I-V) and capacitance-voltage (C-V) measurements were conducted to evaluate the diode performance and interface state dynamics. The results show that samples with higher resistivity, particularly those deposited at room temperature (S1 and S2), exhibit MOS-like behavior, indicating higher concentrations of interface states and defects. In contrast, samples deposited at elevated temperatures (S3, S4, and S5) demonstrate improved diode characteristics, with lower resistivity, enhanced carrier mobility, and better crystalline quality. Mott-Schottky and capacitance-frequency (C-f) analyses further reveal the significant role of interface states in determining the heterojunction's electrical response, especially at lower frequencies where charge trapping dominates. Additionally, photoluminescence (PL) spectra confirm the presence of oxygen vacancies in the AZO films, with strong visible emission observed in S1 and S2, linked to deep-level defect states. This work highlights the critical influence of deposition conditions on the resistivity and performance of AZO films in heterojunction-based optoelectronic devices, offering valuable insights into optimizing material properties for improved device efficiency.

Physical and Magnetic Properties of Silicon Doped with Impurity Germanium Atoms

Nurulla F. Zikrillaev — 2025-03-03

This paper presents the results of a study of silicon diffusion-doped with germanium impurity atoms. For the diffusion of germanium impurity atoms, the original single-crystal silicon of the KEF-100 brand was used, in which the phosphorus concentration was equal to Np≈5ꞏ10¹³cm^-3. The selection of such a concentration of phosphorus impurity atoms was justified by the fact that this concentration of phosphorus atoms has practically no effect on the electrophysical properties of the obtained samples of silicon doped with germanium impurity atoms (Si<Ge>) due to the high solubility of germanium impurity atoms in silicon. As shown by the conducted experimental studies in silicon samples doped by the developed new technology, there are a number of important practical features as well as, the time of the diffusion process of impurity atoms of germanium in silicon according to the developed new technology is reduced by 2‑2.5 times, the power consumption during diffusion is reduced by 2 times, the formation of various impurities, silicides, both on the surface and at the surface region of silicon and surface erosion are almost completely eliminated. The study of the electrophysical and magnetic properties of silicon doped with impurity atoms of germanium showed that on the surface and in the near-surface, in addition to the formation of saturated layers of impurity atoms of germanium, binary compounds Ge_xSi_1-xare also formed. Based on the X-ray energy dispersive microanalysis, it was determined that the concentration of silicon atoms on the surface is ~44.32%, germanium atoms ~38.11%, oxygen atoms ~15.58% and carbon atoms ~1.98%. These data showed that the number of germanium atoms on the surface is almost half the number of the main silicon atoms. The presence of impurity germanium atoms leads to a strong change in the fundamental parameters of the original silicon. The results of the study showed that in the samples of silicon doped with impurity germanium atoms, ferromagnetic properties are observed at relatively high temperatures (T = 300 K). For the first time in the samples of silicon doped with impurity germanium atoms, galvanomagnetic parameters such as M_s-saturation magnetization, M_r-residual magnetization and H_c-coercive force were determined. It was shown that in samples of silicon doped with impurity atoms of germanium, the fundamental parameters (the value of the width of the forbidden zone, mobility and band structure) of the original silicon change in a wide range, which leads to an expansion of the spectral range of photosensitivity, as well as magnetic properties, i.e. ferromagnetism is observed at relatively high temperatures (T=300 K).

Strain-Resistive Properties of (Bi0.23Sb0.75)2Te3 Films at One-Sided Cyclic Alternating Strains

Rustamjon U. Siddikov — 2025-03-03

The results of a study of the deformation characteristics of polycrystalline films from the (Bi_0.25Sb_0.75)₂Te₃ solid solution at one-sided cyclic alternating mechanical stresses is presented. The films were obtained on a polyamide substrate by the method of thermal vacuum condensation of molecular beams and had a columnar porous structure with the dimensions of individual crystalline grains of 2.0-2.5 µm. The effect of static and cyclic deformations on the electrical resistance and volt-ampere characteristics of strain gauge films was studied in order to manufacture strain gauges for fatigue damage accumulation on their basis. It was shown that at room temperature such films have an abnormally high static strain sensitivity G ≈ 10³ arb. units and a significant hysteresis of their resistance change was detected at small numbers of alternating deformation cycles. As a result of N = 5∙10⁵ deformation cycles, the linear section of the volt-ampere characteristic expands from (0-5) V at N = 0 to (0‑12) V. And the temperature coefficient of resistance in the range of 293 K-T_min changes from α = -5.6∙10^-3 K^-1 to α = -2.5∙10^-4 K^-1. The characteristic value of T_min, at which α = 0, increases with the growth of N. The studied strain gauge films can be successfully used as a sensor of fatigue stress accumulation in the temperature range of T = 273-413 K and the value of N = 0 – 5∙10⁵.

Optical Investigation of ZnS/GaAs and CuGaS2/GaP Systems

Kh.N. Ahmadova — 2025-03-03

ZnS and CuGaS₂ are materials with a wide range of applications in modern optoelectronics. These materials are used for IR windows as well as lenses in the thermal band, where multispectral maximum transmission and lowest absorption are required. Precisely because of these characteristics, extensive and accurate optical research is necessary. This work has developed an ellipsometric approach for ZnS/GaAs and CuGaS₂/GaP film/substrate systems to address direct ellipsometry tasks. The proposed approach enables us to determine the effects of lattice mismatch on the optical indicatrix of the stressed film being considered through ellipsometric parameters.

Analytic Analysis of the Features of GaAs/Si Radial Heterojunctions: Influence of Temperature and Concentration

Jo`shqin Sh. Abdullayev — 2025-03-03

In this article, we analytically study the electrophysical features of the p-Si/n-GaAs radial heterojunction (RHJ) over a temperature range of 50 K to 500 K, in increments of 50 K while considering various doping concentrations. The analysis encompasses band gap narrowing (BGN), the differences in the band gap between GaAs and Si as a function of temperature, and the built-in potential relative to temperature. In particular, we focus on core p-Si with a radius of 0.5 μm and shell n-GaAs with a radius of 1 μm within the structure. Our findings indicate that the thickness of the depletion region in the p-Si/n-GaAs (RHJ) increases with rising temperature. The band gap difference between GaAs and Si is 0.31 eV at 300 K in our model, which is in good agreement with the experimental results. Additionally, the conduction band offset ∆E_C=0.04 eV and the valence band offset ∆E_V=0.27eV were calculated at 300 K. When the doping concentration changes from 2∙10¹⁵ to 2∙10¹⁸ band gap narrowing (BGN) decreases by 2 meV. Additionally, the built-in potential of the p-Si/n-GaAs (RHJ) decreases by 76 mV with increasing temperature.

Modeling and Theoretical Study of p-n Heterojunctions Based on CdTe/Si: Band Alignment, Carrier Transport, and Temperature-Dependent Electrophysical Properties

Sadula O. Sadullaev — 2025-03-03

This paper presents a comprehensive theoretical study of p-n heterojunctions formed between cadmium telluride (CdTe) and silicon (Si) over the temperature range of 0 K to 800 K. We focus on band alignment, carrier transport mechanisms, and the temperature-dependent electrophysical properties of the heterojunctions. Through modeling approaches, we explore the energy band structure, intrinsic concentration, intrinsic electrical conductivity, and the impact of temperature variations on the heterojunction characteristics. Our findings provide insights into optimizing the performance of CdTe/Si heterojunctions for applications in photovoltaics and optoelectronics.

Graphene Oxide and Reduced Graphene Oxide as Hole Transport Layers for Improved

Denet Davis — 2025-03-03

A growing area of research in recent years has focused on improving the efficiency of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) fullerene-based bulk heterojunction organic solar cells (BHJOSC) using poly 3-hexylthiophene-2,5-diyl (P3HT) as the donor and graphene derivatives as the hole transport layer (HTL). Graphene derivatives, mainly graphene oxide (GO) and reduced graphene oxide (RGO), possess similar exceptional characteristics as that of graphene, and are good candidates as HTL in P3HT:PCBM based BHJOSC’s. In this work, we use, One-Dimensional Solar Cell Capacitance Simulator (SCAPS1D) for the extensive and detailed study of two configurations, namely ITO/GO/P3HT:PCBM/Al and ITO/RGO/P3HT: PCBM/Al. Both configurations are optimized, and enhanced efficiencies are achieved by varying electrical input parameters of the device. Thereafter, design, simulation and analysis of different device combinations are done using nine distinct ETL’s and three metal electrodes. ITO/GO/P3HT:PCBM/LiF/Ca and ITO/RGO/ P3HT:PCBM/LiF/Ca gave improved efficiencies of 8.00% and 12.00% respectively. Then, the influence of varying donor density of Lithium Fluoride (LiF), and effect of varying work function of Indium Tin oxide (ITO), on the device performance of these two devices is studied. A record efficiency of 16.47%, is attained for increased donor density of LiF in ITO/RGO/P3HT:PCBM/LiF/Ca configuration.

Obtaining and Measuring Impedance Characteristics of the Ag8SiSe6 Compound

R.М. Sardarly — 2025-03-03

Samples of the Ag₈SiSe₆ compound were obtained by direct alloying of initial components and subsequent pressing of powders under a pressure of 0.7 GPa. Temperature dependences of conductivity (σ(T)) and permittivity (ε(T)) of the Ag₈SiSe₆ compound were studied in constant and alternating electric fields. In a constant field, the electrical conductivity is found to decrease over time (σ(t)). This phenomenon is associated with the process of charge accumulation at the interface of the ion sample and the blocking electrode. Complex impedance spectra were studied in the frequency range of 20–10⁶ Hz.

Effect of Impurity and Radiation Defects on Anisotropy of Yb-Doped GaS Single Crystal

R.S. Madatov — 2025-03-03

The effect of γ-quanta on the anisotropy of GaS layered single crystal, pure and alloyed with 0.1at% Yb, has been studied at a temperature range of 125-300K. Since the difference between the ionic radius of the Yb-atom and the ionic radius of the component atoms is relatively small when the studied GaS monocrystal is added with itterbium ions, the additive atom is likely to be located both inside the layers (replacing the Ga atom or between nodes) and in interlayer space. The location of impurity atoms and radiation defects in the interlayer region of the layered GaS (Yb) crystal weakens the anisotropic properties of the crystals, and the location inside the layer strengthens them. The mechanism of current flow in high electric fields follows the Frenkel model, regardless of the nature of the impurity atom.

Influence of Linear Doping Profiles on the Electrophysical Features of p-n Junctions

Jo`shqin Abdullayev — 2025-03-03

This study investigated the impact of linear graded doping concentrations on the electrophysical properties of p-n junctions based on Si and GaAs. Doping gradients ranged from 1∙10¹⁶ to 1∙10²⁰ cm⁻⁴, and the analysis was performed at temperatures between 200 K and 500 K, in 100 K increments. The Poisson equation was solved for linear doping profiles, with analytical solutions derived for both Si and GaAs materials. These solutions provided detailed insights into the electric field, potential distributions, built-in potential, and the width of the depletion region. For both materials, the built-in potential was temperature-dependent, with Si exhibiting a more significant variation due to its higher intrinsic carrier concentration. The depletion region width was influenced by both doping concentration and temperature, with GaAs showing a more pronounced variation in width, owing to its distinct material properties compared to Si. The results highlight the crucial role of doping gradients and temperature variations in shaping the performance of the linear graded p-n junctions, offering valuable implications for the design of semiconductor devices such as diodes and transistors optimized for different temperature conditions.

Optical Performance and Crystal Structure of TiO2 Thin Film on Glass Substrate Grown by Atomic Layer Deposition

Temur K, Turdaliev — 2025-03-03

This study investigates the formation of the optical properties and crystal structure of TiO₂ thin films, with a thickness of approximately 1.5 micrometers, grown on a glass substrate using the atomic layer deposition method with titanium tetraisopropoxide and water as precursors. X-ray diffraction and Raman spectroscopy analyses confirmed that the TiO₂ films crystallize in the anatase polymorphic phase. The films exhibit a nanocrystalline structure with an average crystallite size of approximately 28 nanometers, as established by X-ray diffraction measurements. The X-ray diffraction pattern revealed distinct peaks at 2θ angles of 25.3°, 38.6°, 48.0°, 55.0°, and 70.4°, corresponding to the (101), (112), (020), (121), and (220) crystallographic planes, while the Raman spectra exhibited pronounced peaks at frequencies of 143, 194, 392, 514, and 637 cm⁻¹, all characteristic of the anatase phase of TiO₂. The Tauc method applied to the absorption spectra of the thin film showed that it has a direct bandgap of 3.2 eV and an indirect bandgap of 2.3 eV.

Morphological Studies of (Ge2)1-X(ZnSe)X Solid Solutions

A.Sh. Razzokov — 2025-03-03

Single-crystal films of the (Ge₂)_1-x(ZnSe)_x solid solution from a limited tin solution-melt in the temperature range from 1023 K to 803 K at a cooling rate of 1-1.5 K/min on an EPOC installation were grown on Ge substrates and GaAs. The gap between the substrates was 0.65÷1.2 mm. It was established that the lowest values of dislocation density (N_D=2·10⁴÷10⁵cm^-2) were recorded in epitaxial films at T_NC = 893 K. Technological conditions for obtaining GaAs- (Ge₂)_1-x(ZnSe)_x heterostructure with a smooth boundary have been achieved. Film substrate and the supercooling temperature was ΔT = 7.2°C.

Influence of Implantation of Active Metal Ions on the Composition, Emission and Optical Properties of MgO Films

M.B. Yusupjonova — 2025-03-03

The composition, electronic structure, emission and optical properties of MgO/Mg films implanted with Ba+ and Na+ ions before and after annealing were studied by using a combination of secondary and photoelectron spectroscopy methods. It has been shown that after ion implantation, amorphous films consisting of Mg – Ba – O, Mg – O, Ba – O compounds, as well as unbound Ba and Mg atoms, are formed in the surface layers. In this case, ej of the surface decreases. It has been determined that the emission efficiency of ion-doped layers is higher than that of MgO layers. Post-implantation annealing at T = 900 K leads to the formation of a homogeneous Mg_0.4Ba_0.6O film with a thickness of 30 – 35 Å in the case of Ba⁺ ion implantation. It has been revealed that the photoelectron escape depth l of the three-component film is 1.5 times greater than that of Mg oxide. The main mechanisms of changes in the electronic structure, emission and optical properties of MgO during ion implantation and subsequent annealing have been identified.

Influence of SiO2 Nanoparticles on the Characteristics of a Polyvinyl Alcohol-Based Proton Exchange Composite Membrane

U.F. Berdiev — 2025-03-03

This paper presents a study of nanocomposite membranes based on cross-linked polyvinyl alcohol with silica nanoparticles, fabricated by solution casting, for application in vanadium redox batteries (VRFBs). The structure of the membranes was studied by Fourier transform infrared spectroscopy (FT-IR). It was found that the nanoparticles were successfully integrated into the matrix of the proton exchange membrane to improve its performance. The synthesis of silica nanoparticles by in situ sol-gel method in polymer solution showed better performance compared to the addition of prepared nanoparticles. The membrane properties such as mechanical properties, water absorption, ion exchange material (IEM), proton conductivity and permeability to vanadium ions were investigated. The nanocomposite membranes showed higher water absorption, IEM and lower permeability for vanadium ions compared to Nafion117 membrane. The test results of single cell VRFB with nanocomposite membranes showed higher Coulomb yield (CE) and efficiency (EE) up to 81.51% compared to Nafion117. The self-discharge rate of VRFBs with nanocomposite membranes was lower than that of Nafion117. After 50 test cycles, the nanocomposite membrane showed stable battery performance. The results indicate that nanocomposite membranes are a promising and affordable alternative material for Nafion117 in VRFBs.

The Analysis of the Ion Beam Composition of InSb and (InSb)0.98Bi0.02 Obtained by Liquid Metal Ion Source

F.E. Mammadov — 2025-03-03

To investigate the mass composition of the ion beam obtained through field ion emission, a mass analyzer designed analogous to the Wien velocity filter was utilized. This Wien filter analyzer operates based on the principle of intersecting mutually perpendicular electric and magnetic fields (E×B) to classify charged particles according to their mass and charge. The ion beam was obtained using mInSb and InSb_0.98Bi_0.02as the working The mass composition of the ion group was analyzed using this method. In the experiments, it was found that the ion beam obtained using InSb as the working substance had a homogeneous composition, consisting solely of (InSb)⁺ ions. However, in contrast, when the working substance was (InSb)_0.98Bi_0.02, it was determined that the ion beam had a miscellaneous composition. In addition to (InSb)⁺ ions, the ion beam was found to contain ((InSb)_0.98Bi_0.02)⁺ and (Bi)⁺ ions.

Doping of Silicon with Gadolinium Atoms – Structural Distribution and Raman Spectral Changes

Sh.B. Utamuradova — 2025-03-03

In this study, we investigated silicon samples doped with gadolinium using two different methods: incorporation during growth and diffusion treatment at elevated temperatures. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to analyze the surface microstructure and impurity atom distribution, while Raman spectroscopy revealed characteristic phonon mode shifts induced by gadolinium doping. It was found that doping during growth results in a more uniform structure with fewer large defects, although localized regions enriched in carbon and oxygen remain. In contrast, diffusion doping leads to the formation of pronounced inhomogeneities, indicating significant dislocation formation and structural defects due to lattice parameter mismatches. The results demonstrate the influence of the doping method on the silicon surface state, elastic stress distribution, and the emergence of new vibrational modes, which can be utilized for the targeted modification of material properties in spintronic, optoelectronic, and sensor devices.

Comparative Study and Analytical Modeling of AlGaN/GaN HEMT and MOSHEMT Based Biosensors for Biomolecules Detection

Abdellah Bouguenna — 2025-03-03

In this study, a model has been developed to analyze AlGaN/GaN high-electron-transistor (HEMT) and metal-oxide semiconductor high-electron-transistor (MOSHEMT) based biosensors. The model focuses on detecting biomolecules such as ChOx, protein, streptavidin and uricase by modulating the dielectric constant. The sensitivity parameters used for biomolecule detection include drain current, transconductance, and drain off sensitivity. The dielectric constant is adjusted based on the specific biomolecule being sensed by the biosensor. The variation in dielectric leads to changes in drain current, with an increase or decrease depending on the positive charge of the biomolecules. The HEMT device exhibits greater variations in drain current, transconductance, and drain off sensitivity compared to the MOSHEMT device when the biomolecule is present in the cavity region. The simulation results are validated by comparing them with Atlas-TCAD (atlas-technology computer aided design) and experimental data, showing excellent agreement.

Methods of Correction of Spectral Characteristics of Silicon Photodetectors

Mykola S. Kukurudziak — 2025-03-03

The paper investigates methods for shifting the spectral characteristics of silicon photodiodes toward longer wavelengths. It is established that with increasing the reverse bias voltage of the photodiode, the maximum spectral characteristic shifts towards longer wavelengths due to an increase in the collection coefficient of minority charge carriers, which determines the appearance of the spectral characteristic. With an increase in the lifetime of minor charge carriers and the resistivity of the photodiode base material, the maximum of its spectral characteristic also shifts towards longer wavelengths. Increasing the n⁺-junction depth of the photodiode reduces the effect of background short-wave radiation on the useful signal of the photodiode. Silicon cut-off adsorption light filters have been proposed that eliminate the influence of background radiation with a wavelength of less than 800 nm on the photodiode signal and have a transmittance of about 75% at a wavelength of 1064 nm.

Possibilities of Using Ukrainian Clinoptilolite (Sokyrnytsia Deposit) in Nuclear Energy

Oleksii Yu. Lonin — 2025-03-03

The clinoptilolite from the Sokyrnytsia deposit belongs to the zeolite family and is known for its application as sorbents in nuclear energy. The sorption of cesium, strontium, cobalt, and europium ions by clinoptilolite has been studied. The research examined how the composition and structure of clinoptilolite influence sorption. Sorption properties were assessed using the sorption coefficient, which quantitatively measures clinoptilolite's interaction with radionuclides. The results revealed that clinoptilolite exhibits the highest sorption efficiency for cesium (87.0%) and strontium (80.5%). Europium showed a sorption efficiency of 73.0%, while cobalt exhibited a lower sorption efficiency of 60.0%. The study established an ion exchange sequence for these ions in the sorption process and observed a dependency on the ionic radius of the sorbed ions. The presence and concentration of competing ions significantly affected the sorption efficiency. For instance, sodium ions in the solution reduced sorption by up to 25%, depending on the radionuclide. Increased sodium ion concentration caused an additional 26% to 40% sorption reduction. Similarly, tripling the strontium concentration in the solution reduced the sorption effect. The sorption experiments were conducted under both static and dynamic conditions. Radionuclide content was determined using the characteristic X-ray emission (XRE) method. This technique analyzes the characteristic X-ray radiation of radionuclides excited by a proton beam. The experiments were carried out at the analytical nuclear-physical complex "Sokil." Samples were irradiated in the XRE channel, where targets were placed in a cassette within an irradiation chamber under a vacuum of 10⁻⁴ Pa. The proton beam, with a current of 200 nA and an energy of 1600 keV, was used to excite the X-ray radiation of cesium, strontium, and cobalt atoms. The characteristic X-ray radiation of the K-series of strontium atoms was detected using two detectors: the XR-100CR Si-PIN X-ray detector and the Ge(HP) detector. Considering its established radionuclide selectivity sequence, the clinoptilolite from the Sokyrnytsia deposit can be utilized in Ukraine's nuclear energy industry.

Determination of Setup Margin for Nasopharyngeal Carcinoma by Using Electroinc Portal Imaging Device

Safa Elfaramawy — 2025-03-03

Introduction: This study aimed to assess three-dimensional (3D) setup mistakes and provide optimal margins for planned target volume (PTV) coverage in head and neck radiation. Methods: Ten patients participated in the trial, receiving IMRT in conjunction with weekly electronic portal imaging (EPI). A total of 170 portal pictures were analyzed. The systematic (S) and random (s) errors in the population of patients with head and neck cancer were assessed using portal images in the caudocranial longitudinal (CC) and left-right lateral (LR) orientations, measured within the anterior-posterior (AP) field. The clinical-to-planning target volume (CTV-PTV) margins were determined in accordance with ICRU Report 62 guidelines and van Herk’s formulae. Results: The group systematic errors and random errors were 0.19 and 0.26 cm , respectively in the anteroposterior direction; the group systematic errors and random errors were 0.15 cm and 0.24 cm in SI direction, respectively; the group systematic errors and random errors were 0.13 cm and 0.25 cm in LR direction, respectively; According to the classical van-Herk formula MPTV =2.5Σ +0.7σ, we figured out the ideal PTV margins (MPTV) based on the setup errors and 0.65 cm, 0.55 cm, and 0.5 cm were required in the AP, SI, and RL directions. Discussion and conclusions: we can conclude that a 6-mm extension of CTV to PTV margin, as the optimal margin and can be reduced with increasing frequency of online verification (daily imaging) or for patients where the prescribed does not exceed tolerance doses for organs at risk.

Casson Flow of Blood Containing Au and Ta Nanoparticles Over a Stenotic Artery

Suneetha Sangapatnam — 2025-03-03

Computational fluid dynamics focuses a premium on investigations of blood flow via narrowed arteries due to the relevance of these issues to biological investigations. The main goal of this study is to find out how nanoparticles affect blood flow via a constricted artery. As part of our investigation into the theoretical flow scenario, we examine the significance of Casson nanofluid movement via a cardiac artery. By using the suitable delf similarity variables the PDEs transformed into ODEs. Following that, the dimensionless equations are handled employing the MATLAB computer program in the Bvp5c method. The magnetic properties of the blood flow cells were investigated by increasing the magnetic field parameter, which resulted in a reduction in blood flow as predicted. The movement trend reduced when the Casson liquid parameter increased. To improve the transmission of heat efficiency, the concentration of gold particles in the constricted artery should be increased. One may argue that iron nanoparticles are useful for delivering medications. Presently available methods may be useful for distributing drugs throughout the circulatory system. The theoretical consequences of this medication delivery method are presented in a manner that is made easier by the utilization of an illustration representation

Blood Flow Analysis Through an Inclined Artery Having Multiple Stenosis with Variable Nano Fluid Viscosity Using Single Wall Carbon Nanotube (SWCNT)

Syed Nisar Ahmed — 2025-03-03

The steady flow of viscous fluid flow through an inclined tube of the non-uniform cross-section including multiple stenoses has been investigated under the influence of a single-wall carbon Nanotube (SWCNT). We linearized the flow equations and determined the flow resistance and wall shear stress expressions assuming mild stenoses. Studies have examined how parameters affect flow variables. It is found that the resistance of the flow increases with stenoses height. It is also interesting to notice that the wall shear stress decreases with the increase of the height of stenoses. It is also observed that the resistance to the flow (λ^–) increases with inclination (α), source and sink parameter (β), Grashof number (B_r) , dynamic viscosity (μ) and flux (q). The velocity profiles are presented in the form of streamlines.

Analysis of the Properties of Vacancy Mediated Methyl Ammonium Lead Iodide Perovskite: A DFT Based Study

Md. Abdullah Al Asad — 2025-03-03

Intrinsic defects have a significant impact on carrier transport properties of Methyl Ammonium Lead Iodide (MAPI) Perovskite CH₃NH₃PbI₃. In this paper, we investigated how lead vacancies affect the photovoltaic properties of MAPI using density functional theory (DFT) studies. Lead vacancies in perovskite materials can significantly impact carrier dynamics and device efficiency. Our findings indicate that the lower energy configuration of the Pb vacancy does not create deep trap states that would otherwise reduce carrier lifetime. This suggests that Pb vacancies in MAPI might not be as detrimental to carrier dynamics as previously thought. Pb vacancies could potentially be compensated by other defects or dopants in the material, which might mitigate their negative effects on carrier dynamics. The introduction of a Pb vacancy leads to additional electronic states near the conduction band minimum (CBM) within the fundamental band gap. This indicates that the vacancy introduces localized electronic states that influence carrier behavior. The Highest Occupied Molecular Orbital (HOMO) becomes more localized around the vacant area, while the Least Unoccupied Molecular Orbitals (LUMOs) are only partially localized. This localization around the vacancy does not create strong trapping states that could hinder carrier movement. The presence of vacancies causes atomic movements that result in a more distorted optimized structure. This structural distortion can influence the overall material properties and potentially impact device performance. The HOMO and LUMO levels are primarily derived from the p orbitals of the atoms involved. This highlights the importance of p orbital interactions in determining the electronic properties of the material

A New Fourth Order Compression Dependent Equation of State

Abhay P. Srivastava — 2025-03-03

This study introduces a new first- to fourth-order exponential equation of state (EOS) to enhance accuracy across varying compression levels. The proposed exponential EOS is compared to the widely used fourth-order Birch-Murnaghan EOS, and it not only matches but surpasses precision, especially at high compression. This comparison serves as a clear benchmark for the readers to understand the superiority of the new model. The findings of this study are crucial, as they reveal that the fourth-order exponential EOS provides an unmatched accuracy level at higher compression, notably for materials like HCP-iron and sodium halides. The Birch-Murnaghan EOS, though effective at low compression, deviates from experimental values at higher levels. Additionally, the study examines the Shanker EOS, in which M. Kumar et al. [Physica B: Condensed Matter, 239(3-4), 337-344 (1997)] suggest the requirement to improve at high compression and improve by fitting parameters that vary from material to material. This limitation is removed by developing the fourth-order exponential EOS, which is more versatile, offering reliable results across both low- and high-compression scenarios in high-pressure physics.

Analysis of Higher Overtone Vibrational Frequencies in Cyclohexane Using a Lie Algebraic Approach

J. Vijayasekhar — 2025-03-03

This study contains a sophisticated computational approach to predict cyclohexane while maintaining the D3d point group symmetry higher overtone vibrational frequencies (C₆H₁₂), precisely, third, fourth, and fifth. We utilize a Lie algebraic approach within the context of the vibrational Hamiltonian. The method uses cyclohexane's carbon-hydrogen (C-H) and carbon-carbon (C-C) bonds as unitary Lie algebras, accurately modelling the molecular vibrational structure. Thus, the vibrational Hamiltonian takes Casimir and Majorana's invariant operators and parameters and successfully outlines the molecules' vibrational modes. This Lie algebraic approach clearly outlined cyclohexane's higher overtone vibrational dynamics and provided helpful information that can be applied in other fields of study and technology.

On the Influence of Vacuum Conditions on The Power Level of Electromagnetic Waves Generated by A Relativistic Magnetron

A.B. Batrakov — 2025-03-03

The high-power microwave radiation, generated in a relativistic high-voltage pulsed magnetron with the range of 8 mm, was experimentally investigated. The factors that negatively affect the generation of microwave radiation were experimentally studied and analyzed. It was determined that the low pressure in the vacuum diode of the magnetron also was associated with the processes reducing the efficiency and duration of the pulse generation. The air components are known to be the major residual gases in the magnetron vacuum diode. During the magnetron operation, a significant increase in the pressure of the residual atmosphere of hydrocarbons, water vapor, and hydrogen is to be observed. A vacuum system was composed to pump them out, thus ensuring the magnetron optimal operation. A cryogenic condensation-adsorption pump was developed and applied for the new vacuum system allowing to increase the evacuation rate of the main residual gases. The peculiarity of the developed pump is that the pumping element with the adsorbent has a double working surface due to the use of a corrugated form of the sorption cartridge. Another feature of the pump is its efficiency, which is achieved due to the use of nitrogen vapors for cooling the space between the walls. Due to the use of the cryogenic means of pumping, it became possible to obtain the pressure at the level of 1·10^-6 Torr, thus achieving an increase in the microwave radiation of the relativistic magnetron by 25 percent.

Ultrasound Doppler System's Resolution Using Coherent Plane-Wave Compounding Technique

Evgen A. Barannik — 2025-03-03

Among modern ultrasound technologies for medical diagnostics, a special place is held by the technology of compounding plane waves with different propagation directions, which form synthesized images. In this work, based on the previously developed theory of Doppler response formation, the resolution of a system that uses plane wave compounding is investigated. In this case, small nonlinear components in the angle of inclination of the wave vectors of different plane waves were taken into account for the phase of the synthesized response and for the envelope of the radiation pulses. As a result of the study, it was found that the dimensions of the measuring volume in the longitudinal and transverse directions do not change. Taking into account small components leads to a slight change in the shape of the measuring volume, which ceases to be exactly spherical. This is explained by the fact that the resolution is determined not only by the interference of plane waves, but also by the area of their intersection at a certain point in space. The results obtained indicate that neglecting small inclination angles in the envelope is fully justified and allows simplifying the process of obtaining Doppler signal spectra in plane wave compounding technology.

Anisotropic Cosmological Model in a Modified Theory of Gravitation

G. Satyanarayana — 2025-03-03

In this research, spatially homogeneous and anisotropic LRS Bianchi type-I cosmological model in f(R, T) theory is discussed by choosing the specific form as f(R, T) = R + μe^-γR + λT, here R is the Ricci scalar, T is the trace of the energy-momentum tensor, μ, γ, and λ are constants. In this research the functional form consists of an exponential function which is more generalised than linear, quadratic and other polynomials. The solutions of the field equations are derived by considering the following two conditions (i) the scale factor ɑ(t) is considered as a hybrid expansion law. By assumption of this scale factor, we can obtain the deceleration parameter as a function of the time dependent variable (ii) σ ꭀ θ (the proportionality of shear scalar with expansion scalar). For the obtained model, the physical and geometrical properties like as Hubble parameter (H), expansion scalar (θ), volume (V), pressure (p), the energy density (ρ), equation of state (ω) parameter, state-finder parameter (r, s), deceleration parameter (q), jerk parameter (j) are discussed. The graphical behavior of all the parameters of the model is examined with respect to redshift (z) by taking two different values of μ =−2.985, −2.902. In the discussion of all energy conditions, it is noticed that DEC is satisfied for both the values of μ, whereas NEC is satisfied in past (z > 0), present (z = 0), and violated in future (z < 0) for μ = −2.985, −2.902. For both values of μ, the SEC is violated. The violation of SEC represents the accelerating expansion of the cosmos. The obtained results in the model match with recent observational data.

Modulating Effects of Polyphenols on The Interactions Between Functional Proteins and Amyloid Fibrils

U. Malovytsia — 2025-03-03

The present study was focused on the investigation of the binary and ternary systems containing the functional proteins, polyphenols and amyloid fibrils using the differential absorption spectroscopy, intrinsic protein fluorescence and fluorescent probe techniques. The group of polyphenols (PF) included the representatives of four different classes: flavonoid quercetin (QR), phenolic acid (salicylic acid, SA), curcuminoid curcumin (CR) and tannin gallic acid (GA). The functionally important proteins were represented by hemoglobin (Hb), cytochrome c (Ct) and serum albumin (BSA). The amyloid fibrils were prepared from the N-terminal (1-83) fragment of apolipoprotein A-I with amyloidogenic mutation G26R (ApoA-IF). It was demonstrated that the spectral markers such as the position and intensity of the bands in differential absorption spectra, fluorescence intensity and emission maxima of the intrinsic (Trp) and extrinsic (TDV) fluorophores can be regarded as sensitive indicators of the protein structural modifications induced by amyloid fibrils and polyphenols. The observed changes in the Trp and TDV fluorescence were interpreted in terms of several processes: i) PF-induced conformational changes of the protein molecules accompanied by the alterations in microenvironment of Trp residues; ii) competition between PF and TDV for the protein binding sites; iii) non-resonance quenching of Trp or TDV fluorescence by PF; iv) resonance quenching (Forster resonance energy transfer) between Trp or TDV and PF. Taken together, the results obtained suggest that polyphenolic compounds can modulate the interaсtions between functional proteins and amyloid fibrils and can be considered as perspective agents for reducing the amyloid toxicity.

Computational Study of Drug Delivery Systems with Radionuclide and Fluorescence Imaging Modalities. II. Doxorubicin Delivery Systems Based on Albumin and Transferrin

V. Trusova — 2025-03-03

This study explores the development of advanced protein-based drug delivery systems for doxorubicin (DOX), an anticancer agent, incorporating both radionuclide (technetium-99m complexes) and fluorescence (Methylene Blue (MB), Indocyanine Green (IG), cyanine AK7-5 and squaraine SQ1) imaging modalities. Building upon previous research on albumin-based carriers, this work expands the scope by introducing transferrin (TRF) as a complementary protein component to create a more sophisticated and targeted delivery platform. Molecular docking technique was employed to design and characterize the multimodal delivery systems that incorporate radiopharmaceuticals and near-infrared fluorescent dyes. The results demonstrate that technetium-99m-based radiopharmaceuticals are capable of strong noncovalent binding to human serum albumin (HSA) and its complexes with transferrin. A comprehensive analysis of docking scores and interacting amino acid residues reveals that HSA-TRF-TcHyn/TcMEB/TcDIS-DOX-IG/SQ1 systems show the highest potential for experimental testing and further development. These findings support the potential of HSA-TRF complexes as nanocarriers with dual imaging capabilities for DOX delivery, offering an approach to enhance therapeutic efficacy while reducing systemic toxicity in anticancer treatment.

Slow Surface Electromagnetic Waves on a mu-Negative Cylinder

Victor Galaydych — 2025-03-03

This paper presents the theoretical study of metamaterials with negative magnetic permeability. The electrodynamics phenomenological description has been chosen. The dispersion properties of slow surface electromagnetic waves propagating along a circular cylinder made of mu-negative metamaterial are studied. We neglect energy losses in the metamaterial. Negativity of permeability occurs in relatively bounded frequency intervals, and for all modes, a normal dispersion occurs, regardless of parameter values. The values of phase velocities of these waves lie between c and 0.3c. The phase velocity dependencies of the studied modes versus their frequency have a diverse appearance. The directions of group and phase velocities coincide. The values of group velocity are less than 0.002c. The wave fields are the superposition of transverse-electric and transverse-magnetic parts and decay exponentially in a radial direction away from the separating boundary. The wave fields penetrate mu- negative metamaterial much weaker than into a vacuum. Wave propagation in the structure does not require an external magnetic field. The variety of these wave features on the cylinder parameters can be used for different applications.

Interaction Between a Spherical Particle and Atmospheric Pressure Currentless Argon Plasma

Shiyi Gao — 2025-03-03

The interaction between a spherical particle of radius 10−5 − 10−3 m and atmospheric pressure currentless argon plasma was studied numerically within the hydrodynamic approach. The nonlinear problem was solved taking into account the temperature dependencies of transport and kinetic coefficients. A two-temperature model, which considers plasma thermal and ionization non-equilibrium near the particle, was used. The boundary condition for electron heat flux on the outer boundary of the space charge sheath is discussed in detail. The spatial distributions of plasma characteristics, such as temperature and number density, near the particle were determined and analyzed. The heat flux from plasma to the particle was calculated over a wide temperature range of singly ionized argon plasma.

Multilayer WNbN/WNbC, WN/WC and NbN/NbC Coatings: Vacuum-Arc Deposition Strategy and Microstructure Assessment

O.V. Maksakova — 2025-03-03

Reactive gases such as nitrogen, oxygen, and carbon-based gases (e.g., acetylene) are introduced into the generated plasma flow to create coatings with chemical compounds including nitrides, oxides, and carbides. By managing the rate of gas addition, the stoichiometric composition of the material, which influences its crystal structure and range of properties, can be controlled. In light of this, the vacuum-arc PVD technique was utilised to deposit carbide/nitride multilayer coatings based on W and Nb in a dynamically changing atmosphere of nitrogen and acetylene gases. The two-channel control device – “evaporator-injector” – was employed to control the functions of vacuum-arc evaporators and the gas introduction ports in the vacuum chamber of the installation. The material of the substrates for the deposition of coatings was corrosion-resistant high-temperature steel (grade 12X18H9T). The W (99.97 wt.%) and Nb (98.2 wt.%) cathodes were produced through mechanical boring of ingots made from the respective metals obtained via electron beam re-melting. The present work reports on the deposition strategy of vacuum-arc multilayer WNbN/WNbC, WN/WC, and NbN/NbC coatings with nanometre layer thicknesses and a preliminary assessment of their microstructure. The multilayer systems presented have yet to be studied and hold considerable scientific interest regarding synthesis and experimental investigation.

Interaction of Heavy Metals with 7S Soybean Globulin: Molecular Dynamics Study

O. Zhytnyakivska — 2025-03-03

Molecular dynamics (MD) simulations were performed to examine the structural and dynamic effects of Cd²⁺ and Co³⁺ binding on 7S soybean globulin. Using a 200 ns simulation at 300 K with GROMACS and the CHARMM General Force Field, key structural parameters—including root-mean-square deviation (RMSD), radius of gyration (Rg), solvent-accessible surface area (SASA), and root-mean-square fluctuations (RMSF)—were analyzed to assess protein stability, flexibility, and compactness under varying metal ion concentrations. The results of the MD simulation indicate: i) at low metal concentrations, the protein maintained structural stability with minimal deviations; ii) increasing metal ion concentrations induced distinct structural changes in the protein structure depending on the ion type; iii) lower metal concentrations primarily affected specific regions of the α-subunit, whereas higher concentrations influenced both the α- and β-subunits; iv) fluctuations in secondary structure elements—α-helices, 3₁₀-helices, and β-strands—suggested potential destabilization, particularly in systems with high metal concentrations; v) α-helical content remained stable throughout the simulation, a slight decrease in β-sheet content was observed at higher metal concentrations. This suggests that heavy metal binding may have a destabilizing effect on β-sheet structures, altering the overall conformation of 7S globulin. These insights are valuable for the development of protein-based nanomaterials for heavy metal detection and sorption.