East European Journal of Physics

A Spectral-Geometric Formulation of Extended Uncertainty Principles in Quantum Mechanics

Balaji Padhy — 2026-03-14

The Heisenberg uncertainty principle is foundational to quantum mechanics, yet its standard formulation is limited to Hilbert space operator commutators. Recent advances in noncommutative geometry (NCG) allow a reformulation of quantum observables and spacetime itself using operator algebras, providing a deeper framework for uncertainty relations. In this paper, we develop a generalized uncertainty relation using spectral triples, extending the Robertson– Schrödinger inequality into the noncommutative regime. Explicit derivations are given for operator-valued distances, modified commutators, and position–momentum operators in a noncommutative configuration space. Our results reveal the emergence of a minimal measurable length scale, consistent with predictions from quantum gravity, and demonstrate that uncertainty is fundamentally geometric in origin.

Exploring Cosmological Consequences and Viability of Varying G and Λ with Deceleration Parameter

Asem Jotin Meitei — 2026-03-14

We give a brief review of a spatially homogeneous and anisotropic Bianchi Type-I cosmological model with varying gravitational constant G(t) and cosmological term Λ(t). The Einstein field equations are solved by considering a time-dependent deceleration parameter(DP) and barotropic equation of state (EoS) p=Wρ. The model universe is fit with a scale factor of the form ɑ(t) = (e^Aζ_ct - 1)^1/ζ_c which provides a smooth evolution from a decelerating to an accelerating phase of cosmic expansion. Analytical expressions for the pressure, energy density, G(t) and Λ(t) are derived and their variations with redshift are analyzed. The behaviour of cosmological parameters such as the Hubble function H(z), deceleration parameter q(z), jerk parameter J(z) and Om(z) diagnostic are examined. The present values H₀ = 67.112^+0.049-_0.11km s^-1Mpc^-1, q₀ = -0.2926 and transition redshift z_t = 0.8626 are obtained, consistent with recent observations. Overall, the proposed variable G and Λ Bianchi Type-I model provides a coherent description of the universe’s transition from deceleration to acceleration, consistent with 46 OHD.

Observational Constraints on Plane Symmetric Renyi Holographic Dark Energy Universe with Scalar Fields and Cosmic Strings

U.Y. Divya Prasanthi — 2026-03-14

In this work, we investigate a cosmological model based on a plane symmetric space–time, where the matter content of the Universe is described by Rényi holographic dark energy within the framework of Einstein’s theory of gravitation in the presence of massive scalar fields and cosmic strings. Exact solutions of the field equations are obtained by assuming a specific relation between the metric potentials. Observational constraints on the model parameters are obtained using the latest Hubble cosmic chronometer data through a Markov Chain Monte Carlo analysis. The resulting contour plots provide tight bounds on the free parameters, and the reconstructed Hubble parameter exhibits excellent agreement with the ΛCDM model over the entire redshift range. A detailed investigation of the cosmological parameters reveals that the model successfully reproduces the standard cosmic evolution. The deceleration parameter indicates a matter-dominated, decelerating phase at early epochs (z ≥ 2), followed by a smooth transition to the present accelerated phase and an asymptotic approach to a de Sitter–like expansion in the future. The dark energy equation-of-state parameter evolves dynamically and crosses the phantom divide, exhibiting quintom-like behavior. The ω_de- ω'_de plane analysis places the model predominantly in the freezing region, indicating a stable and rapidly accelerating dark energy phase. Statefinder diagnostics show consistency with ΛCDM at the present epoch, with deviations toward Chaplygin gas–like behavior at late times. Furthermore, the energy condition analysis supports the accelerated expansion through the violation of the strong energy condition at late times. Overall, the model provides a physically viable and observationally consistent description of cosmic evolution beyond the standard ΛCDM scenario.

The Cosmological Dynamics of Tsallis Holographic Dark Energy in Saez-Ballester Gravity

P.E. Satyanarayana — 2026-03-14

We investigate interacting and non-interacting Tsallis Holographic Dark Energy (THDE) models within the framework of Sáez–Ballester (SB) scalar–tensor gravity for anisotropic Bianchi type(BT) II, VIII, and IX Universes. Employing the Hubble horizon as the infrared cutoff, we examine the models without assuming a particular scale factor law. The analysis covers key cosmological parameters, including the deceleration parameter, Hubble parameter, energy densities, skewness, the Equation of State (EoS), and the Squared sound speed. Our findings indicate a continuous phantom-like acceleration (w < −1) with transition redshift z_t ≈ 0.67 and negligible late-time anisotropy, consistent with cosmic microwave background (CMB) bounds. Compared to ΛCDM, the THDE models predict an earlier onset of acceleration and a more negative present-day EoS. However, the presence of negative squared sound speed at higher redshifts signals a classical instability of the dark energy fluid. These results highlight THDE as a viable alternative to ΛCDM in anisotropic cosmologies, while motivating further work with alternative cutoffs or stabilising mechanisms to overcome the instability issue.

Cosmological Diagnostics of Bianchi Type-II Barrow Holographic Dark Energy Universe

U.Y. Divya Prasanthi — 2026-03-14

In this paper, we investigate a Bianchi type II anisotropic cosmological model in the framework of Barrow holographic dark energy, considering both the Hubble horizon and Granda–Oliveros scale as infrared cutoffs. To obtain exact solutions of the Einstein field equations, we assume a suitable relation between the metric potentials. Using Hubble cosmic chronometer data, we constrain the model parameters and obtain the best-fit values b₄ = −0.091+0.013 −0.012 and H₀ = 72.3±2.7 km s⁻¹Mpc⁻¹. The H(z) fit shows excellent agreement with observational data and overlaps with ΛCDM at low redshifts, with mild deviations at higher z. The physical behaviour of the model is examined through a detailed analysis of cosmological parameters. The deceleration parameter q(z) reveals a smooth transition from an early decelerating phase to the present accelerating epoch. The equation of state parameter ω_de shows quintom-like dynamics, evolving across the cosmological constant boundary and entering the phantom regime, consistent with late-time acceleration. Stability is tested using the squared sound speed v_s² , which remains positive in the recent Universe, ensuring classical stability. The ω_de–ω’_dephase plane indicates that both models lie in the freezing region, corresponding to faster acceleration. The statefinder diagnostics (r,s) and (r,q) further confirm the transition from the standard cold dark matter dominated phase to a de Sitter-like attractor, with trajectories showing clear deviations from ΛCDM.

Conceptual Violation of Energy Conditions in Bouncing Cosmology

A.Y. Shaikh — 2026-03-14

This paper focuses on examining the bouncing model within a flat Friedmann–Robertson–Walker (FRW) Universe. The equation of state (EoS) parameter pertaining to the considered model under consideration specifies the Universe's peculiar functioning. The kinematics along with the physical attributes of the model’s dynamic parameters are investigated comprehensively. We explored several energy conditions (ECs) in this scenario. The diagnostic pair of statefinder and the jerk parameter are investigated to identify significantly different cosmic phases. We used the squared sound speed parameter , designed to meet the needs of our model’s stability analysis. Our analysis revealed that outcomes of our study are in accordance with patterns observed in the bouncing scenarios, offering a method to explain the cosmic acceleration as well as the singularity problem in our Universe.

Hybrid Solitary Waves and Shock Waves for Double-Layered Fluid Flow with Dispersion Triplet: Zaremaoghaddam and Gear-Grimshaw Models (mKdV Equation)

Lakhveer Kaur — 2026-03-14

The current paper recovers hybrid solitary waves for double–layered shallow water waves with the basic platform being the mKdV equation. The selected models are the Zaremaoghaddam equation and the Gear–Grimshaw equation. The integration algorithm adopted is the generalized exponential differential function method. This yields hybrid waves that emerge from solitary waves, shock waves and the singular solitary waves. The existence criteria for such waves are also presented as parameter constraints.

Nonlinear Self-Focusing of q-Gaussian Laser Beams in Plasma with Relativistic and Ponderomotive Effects under Linear Absorption

Keshav Walia — 2026-03-14

The current study presents a theoretical analysis of nonlinear self-focusing of q-Gaussian laser beam transiting through unmagnetized plasma by incorporating simultaneous effects of relativistic mass variation and ponderomotive mechanism. Linear absorption is also included to account for energy dissipation during beam propagation. By applying WKB and paraxial approximations, the problem is reduced to 2^nd order differential equation that governs the evolution of laser beam width as a function of normalized propagation distance. The resulting equation is solved numerically using 4^th order Runge-kutta method. A systematic analysis is performed to examine effect of laser intensity, plasma density, absorption coefficient, q-parameter and initial beam radius on self-focusing dynamics of q-Gaussian laser beam. These findings indicate that laser-plasma parameters substantially affect beam dynamics and critically govern self-focusing process.

Benjamin--Feir Instability of Interfacial Gravity--Capillary Waves in a Two-Layer Fluid. Part II. Surface-Tension Effects

Olga Avramenko — 2026-03-14

This second part of the study develops a complete geometric and asymptotic description of how surface tension governs the modulational stability of interfacial waves in a two-layer fluid. Extending the analytical framework of Part~I, surface tension is treated as a freely adjustable parameter, making it possible to trace the nonlinear and dispersive properties of the system across the full range of depth ratios and density contrasts. Using the nonlinear Schrödinger reduction together with long-wave asymptotics, the mechanisms that shape the boundaries between stable and unstable regimes are identified and their dependence on surface tension is quantified.

The long-wave structure is controlled by two special density values that mark the bases of the loop and the corridor on the stability diagrams. Their ordering switches at a threshold that exists only when the lower layer is deeper, and loop-type structures occur only in this regime. A second organising parameter is the classical Bond threshold, at which the dispersive and nonlinear singularities coincide. When surface tension exceeds this value and the upper layer is sufficiently deep, the interaction between resonant and dispersive effects produces a capillary cut that replaces the corridor and characterises strongly capillary, upper-layer-dominated configurations. To unify these observations, the full three-dimensional critical surfaces that separate different types of nonlinear and dispersive behaviour are computed. The familiar loop, corridor, and cut appear as planar sections of these surfaces, and their transitions follow directly from the deformation of the intersection between the resonant and dispersive sheets. Two depth ratios correspond to genuine geometric degeneracies: equal layer depths, where the intersection reduces to a straight line, and the golden-ratio configuration, where the critical surface becomes horizontally tangent at the Bond threshold. Overall, Part~II completes the geometric and physical classification of modulational stability in two-layer interfacial waves and provides a framework for future extensions incorporating shear, external forcing, flexible boundaries, or variable bathymetry.

Self-Focusing Dynamics of Cosh-Gaussian Laser Beams in Absorptive Cold Quantum Plasma Under Relativistic and Ponderomotive Nonlinearities

Deepak Tripathi — 2026-03-14

The current study examines self-focusing behavior of Cosh-Gaussian laser beams in absorptive cold quantum plasma, incorporating merged influence of relativistic mass variation and ponderomotive effects. Applying WKB approximation in combination with paraxial theory, 2^nd order propagation equation describing variation of beam width as a function of normalized distance is derived incorporating effect of linear absorption. The numerical solution of resulting differential equation is obtained by 4^th order Runge-kutta method. Further, a comprehensive parametric study is performed to access effect of laser-plasma parameters such as beam intensity, plasma density, initial beam radius, decentered parameter and absorption coefficient on beam dynamics. The results show that relativistic and ponderomotive nonlinearities enhance self-focusing, whereas absorption reduces it. Comparison with classical relativistic plasma underscores the key role of quantum effects in laser propagation through dense plasmas.

Impact of Hexadecapole Deformation on Fusion Cross Sections of Some Spherical + Deformed Systems in 3S-CMD Model

Jignasha Patel — 2026-03-14

The effect of quadrupole deformation (β₂) on heavy ion fusion is a fact that is well recognized phenomenon. In addition to the influence of quadrupole deformation (β₂), the potential impact of hexadecapole deformation (β₄) on sub-barrier fusion has been a topic of frequent discussion. Recently, a theoretical analysis was performed to examine the impact of hexadecapole deformations (β₄), employing the simplified coupled channels code CCFUS, which incorporates static deformations. In this study, we analyzes the effect of the β₄of the target nucleus on fusion cross sections within the framework of the 3S-CMD model. For this purpose, we have chosen the reactions ¹⁶O + ¹⁵⁴Sm and ¹⁶O + ¹⁷⁴Yb. The present research has calculated the fusion cross sections using the SBPM model as well. The calculated fusion cross sections using 3S-CMD model and SBPM are compared with each other as well as experiment.

Fusion of Weakly-Bound ⁹Be With Heavy Nuclei ²⁰⁸PB: A Multi-Body Three-Stage Classical Molecular Dynamics Approach

Vipul B. Katariya — 2026-03-14

The fusion of the weakly bound ⁹Be nucleus with ²⁰⁸Pb is investigated using a multi-body three-stage classical molecular dynamics (3S-CMD) approach. This model explicitly treats ⁹Be as a cluster of ⁴He and ⁵He, allowing for the relaxation of rigid-body constraints on both projectile fragments and the target. In this paper, the influence of these constraints on the complete fusion (CF) cross-section, considering both central and non-central collisions is studied. Systematic removal of rigidity constraints, particularly on the target and the 9Be fragments, significantly affects the CF cross-section, especially at sub-barrier energies. Calculations show that relaxing these constraints enhances CF, indicating the important role of breakup and internal degrees of freedom. The multibody 3S-CMD model provides a tool for understanding the interplay of breakup and fusion in reactions involving weakly bound nuclei.

Relativistic Configuration-Interaction Photoionization Data for Ne-Like Isoelectronic Sequence

O. Abu Haija — 2026-03-14

Photoionization data for the 1s² 2s²2p⁶(¹S₀) ground state of neon like Ca¹⁰⁺, Sc¹¹⁺, Ti¹²⁺, V¹³⁺, and Cr¹⁴⁺ions are reported. The values of ionization threshold limits, resonance energies, quantum defects, transition rates, and oscillator strengths for various Rydberg series are tabulated. The Relativistic configuration-interaction (RCI) approach, implemented in the Flexible Atomic Code (FAC), was employed to perform all calculations. The RCI results for 2s 2p⁶ (²S_1/2) np resonance series show very good agreement with reported values in the literature. In addition, new calculations on K-shell photoexcitations (1s 2s²2p⁶(²S_1/2) np) in these ions are reported. These results would be valuable for high-precision spectral modeling in astrophysical or laboratory plasmas.

Photometrıc Observatıons of Symbıotıc Star AG PEG

Kh.M. Mikailov — 2026-03-14

In the article, using the AAVSO (American Association of Variable Star Observers) photometric database of the AG Pegasi symbiotic star, a light curve was constructed in the Vis filter for a period of 68 (1954-2022) years. During this period, the brightness of the Ag Peg star changed by approximately 2 magnitudes, reaching from 7.5^m to 9.5^m. Using the Scargle method, the possible periodicities in the light curve were investigated by applying statistical spectral Fourier analysis. Two P=17857^d long and P=815^d short periodic variations were detected in the light curve.

Investigations of the ¹⁴N(γ,2α)⁶Li Reaction

Inna Afanasieva — 2026-03-14

A digital measurement technique of points coordinates along the tracks was developed for the stereo frame photonuclear reaction data bank created in KIPT. The main procedure is the analysis of pixel intensity in the area of tracks. The ¹⁴N(γ,2α) ⁶Li reaction was chosen as a test reaction for measurement. A kinematic scheme for calculating the physical parameters of the reaction was created assuming a two-particle decay mode with the formation of an intermediate excited state. Experimental data and kinematic calculation were compared. Events corresponding to the partial channel of the ¹⁴N(γ,⁶Li)⁸Be₀ reaction with the subsequent two-particle decay ⁸Be → α +α were identified and the partial cross section of this channel was measured. The energy and angular distributions of particles at each decay stage were analyzed.

Determination of ¹⁰B/¹¹B Isotopic Ratio and Concentration of Boron in Stainless Steel by ICP MS

Inna Afanasieva — 2026-03-14

The large thermal neutron absorption cross-section of the ¹⁰B enables the use of boron as a neutron absorber for reactivity control in nuclear reactors. Precise information on both the isotopic composition and boron concentration in absorbing materials is crucial, as the degree of reactivity control depends directly on the ¹⁰B content. In the work, a series of experiments were conducted to determine the boron concentration and isotopic ratio in samples of corrosion-resistant chromium-nickel stainless steel, which is used in the control and protection system rods of nuclear reactors. The study was performed using an inductively coupled plasma mass spectrometer on 5 stainless steel samples with a certified boron mass fraction. The external standard method was used to determine the ¹⁰B/¹¹B isotopic ratio, using the ICP-MS-68A Standard (with a natural ¹⁰B:¹¹B ratio of 19.9:80.1) as a reference. To determine the boron concentration in steel, the isotope dilution method (internal standard method) was used. A known amount of a spike with a specific isotopic ratio was added to samples of unknown boron content. Elemental amorphous boron powder with a ¹⁰B:¹¹B isotopic ratio of 95.0:5.0 was used as the spike. The proposed methods allow determining the isotope ratio and boron concentration in a sample by measuring only the ¹⁰B and ¹¹B isotopes. The results obtained were compared with the manufacturer's certified data. The values coincide within the measurement uncertainty, confirming the reliability of the proposed methods for steel analysis.

A Pythagorean-Fuzzy Nonlocal Reformulation of Quantum Electrodynamics

Supratim Mukherjee — 2026-03-14

Quantum Electrodynamics (QED) is the most precise theory in physics, yet its assumption of pointlike interactions between charged particles and photons leads to ultraviolet divergences that require renormalization. This paper proposes a Pythagorean-Fuzzy Nonlocal Reformulation of QED, embedding structured uncertainty directly into the interaction framework. Each spacetime region is described by a Pythagorean fuzzy field with degrees of membership, non-membership, and hesitation, quantifying how strongly an event participates in an interaction and how precisely it can be localized. The conventional point vertex is replaced by a smooth, gauge-covariant nonlocal coupling modulated by a Lorentz-invariant kernel and the fuzzy field’s defuzzified weight. This structure preserves all symmetries of QED while automatically suppressing short-distance divergences. Ultraviolet divergences are suppressed at their origin, yielding finite self-energy and vacuum-polarization contributions within the nonlocal framework, without the appearance of divergent counter terms. Physically, the formulation interprets quantum interactions as finite “fuzzy” processes distributed over regions of limited definability. Mathematically, it unites the logic of Pythagorean fuzzy sets with the geometry of field theory, providing a natural regularization mechanism that remains fully consistent with standard QED in the sharp-local limit.

Fission Time Scales and Distributions Studied Using a Langevin Dynamical Model

Charmi Vadagama — 2026-03-14

The fission time scale and associated distributions play a crucial role in investigating the full dynamical evolution of the excited compound nucleus. In the present work, we have performed a one-dimensional Langevin dynamical model calculation to simulate the fission time scale and corresponding fission time distributions (FTDs) for ¹²⁵Cs, ²¹³Fr, and ²⁴³Am. The time evolution of the collective deformation coordinate from the ground state to scission is followed under the influence of dissipation, fluctuations, and realistic fission barriers, and a large ensemble of trajectories is used to construct fission–time distributions for each compound nucleus. The results reveal distinct differences in the shapes and widths of the distributions, characterized by extended long-time components that significantly impact the average fission time. Particle evaporation is found to play an important role in shaping the fission time distributions by modifying the excitation energy during the dynamical evolution. These findings emphasize the importance of analyzing the full fission time distribution, rather than relying solely on average values, for a realistic description of fission dynamics.

DFT Study of the Stability, Electronic, Optical, and Thermal Properties of Two-Dimensional BiBr₃ Semiconductor

Yadgar Hussein Shwan — 2026-03-14

Density functional theory (DFT) serves as a first-principles method to thoroughly investigate the stability of the structure and analyse the electronic, optical, and thermal characteristics of two-dimensional bismuth tribromide (2D BiBr₃). Ab-initio molecular dynamic (AIMD) simulations reveal that the structure is thermally stable at 300 K. The BiBr₃ behaves as a semiconductor with a 2.84 eV band gap according to its electronic band structure and partial density of state (PDOS) analysis. Optical characterisation reveals that BiBr₃ has strong interactions in visible and ultraviolet wavelength domains, which shows its potential in the next-generation of optical and optoelectronic devices. A remarkable Seebeck value estimated via Boltzmann transport calculations, highlights the promise of BiBr₃ in low-temperature thermoelectric management. This investigation implies temperature-driven power factor improvement, peaking at 3.25 ×10¹² W/K²·cm·s at 300K. The BiBr₃ exhibits moderate heat capacity at intermediate to high temperatures while keeping very
low thermal conductivity. This highlights its ability to effectively manage heat and serve as an insulator in various applications. The detailed results show that 2D BiBr₃ is a potentially favorable material with diverse possibilities in most technological applications.

Effect of Impurity Clusters on Optical Properties of Nickel and Copper Doped Single-Crystal Silicon

Sirajidin Z. Zainabidinov — 2026-03-14

This paper deals with the influence of impurity atoms on the optical properties of single-crystal silicon doped with nickel and copper during high-temperature diffusion doping. And also, the processes of formation of various chemical compounds involving oxygen, carbon, and atoms of nickel, copper, and silicon. By means of FTIR spectrometry and X-ray diffraction analysis, it was revealed that the concentrations of optically active oxygen and carbon in the volume of silicon samples doped with nickel and copper significantly increase compared to the original samples.

Composition and Radiation-Induced Variations of Thermal Conductivity in Sn₁-ₓTbₓSe Solid Solutions

T.A. Jafarov — 2026-03-14

In this work, the structural, physicochemical, and thermal transport properties of Sn_1-xTb_xSe (0 ≤ x ≤ 0.05) alloys were investigated with respect to terbium concentration and γ-irradiation dose. X-ray diffraction and DTA analyses confirmed the formation of orthorhombic substitutional solid solutions following Vegard’s law, with a slight increase in lattice parameters and microhardness as Tb content increased. The introduction of Tb atoms into the SnSe matrix enhances phonon–defect scattering due to mass fluctuations and lattice distortions, resulting in a pronounced reduction in thermal conductivity, particularly at low doping levels (x ≤ 0.02). Thermal conductivity measurements performed after γ-irradiation (0–6.5 Mrad, ⁶⁰Co source) revealed a general decreasing trend for all compositions. In undoped SnSe, the relative decrease reached ~6%, while in Tb-doped samples, the sensitivity to irradiation was significantly reduced. For doses above 5 Mrad, the dependence k(D) is well described by a linear model with high correlation coefficients. These results demonstrate that Tb incorporation not only suppresses phonon transport, enhancing thermoelectric potential, but also increases the radiation resistance of SnSe-based materials.

Acoustic Properties of Triglycine Sulphate Crystals with Alanine Impurity

E.U. Arzikulov — 2026-03-14

The frequency- and concentration-dependent absorption coefficients of longitudinal and transverse ultrasonic waves in pure and α-alanine-doped triglycine sulfate (α-TGS) crystals (α-alanine content in crystals is: 5, 10, 15, 20, 25, 30, and 35 mol%) grown from solution at room temperature were studied. It is established that absorption coefficients of ultrasonic waves in α-TGS crystals with L and S polarization with the increase in concentration of α-alanine about 1.57 and 1.88 times decrease, and propagation velocity increases by 3.24 and 13.38%, respectively. Decrease of absorption coefficients of transverse ultrasonic waves caused by elastic scattering of phonons on impurity, i.e., decrease of τ, at the corresponding dispersive properties of a phonon subsystem.

First-Principles Investigation of The Electronic Properties of Monolayer MoS₂ Using DFT-Based QuantumATK Simulations

Makhkam Khalilloev — 2026-03-14

In this work, the electronic properties of monolayer molybdenum disulfide (MoS₂) were investigated using density functional theory (DFT) within the QuantumATK simulation environment. The band structure and density of states (DOS) calculations reveal that MoS₂ possesses a direct band gap of 1.74 eV and an indirect band gap of 1.27 eV. Further analysis including partial DOS and charge density distribution was performed to examine the orbital contributions and bonding characteristics. The influence of biaxial strain (±3%) on the electronic structure was also studied, showing a tunable band gap behavior. These results provide valuable insight into the electronic characteristics of MoS2 and support its potential applications in nanoelectronic and flexible device technologies.

Study of the Formation of Radiation Defects in Irradiated Silicon Samples, Doped with Chromium Atoms

Sh.I. Nabiyev — 2026-03-14

This work presents an investigation of radiation-induced defect formation in single-crystal n-type silicon doped with chromium (n-Si<Cr>) using positron annihilation spectroscopy. The initial silicon samples, phosphorus-doped during crystal growth, were subsequently modified by chromium diffusion and then irradiated with 2 MeV protons at a beam current of 0.5 μA using the EG-5 accelerator facility. The measurements revealed the formation of characteristic radiation-induced vacancy-type defects, including A-centers, E-centers, divacancies, and their stable complexes. A comparative analysis of chromium-doped and undoped samples demonstrated a pronounced difference in the accumulation rate of these defects. It was established that the presence of chromium atoms in the bulk of n-type silicon significantly suppresses radiation defect formation: the concentration of vacancy-related defects in n-Si<Cr> was found to be approximately 1.5–2 times lower than in the reference n-Si samples irradiated under identical conditions. These results confirm that chromium doping enhances the radiation resistance of silicon and can be considered an effective approach for modifying semiconductor materials intended for operation in environments with high radiation exposure.

Features of the Thermal Behavior and Phase Formation of BiFeO₃ Using Precursors Activated by Solar Melting

M.S. Payzullakhanov — 2026-03-14

The effect of pretreatment of Bi₂O₃ and Fe₂O₃ oxides on the synthesis and structural characteristics of bismuth ferrite BiFeO3 was studied. It was found that BiFeO3 formation begins at 790÷850 °C, and decomposition occurs above ~920 °C. Preliminary melting of the oxides in a solar furnace shifts the thermal effects to higher temperatures and increases the thermodynamic stability of the phase. X-ray phase analysis revealed the formation of a perovskite-like structure with orthorhombic distortion, high crystallinity, and a crystallite size of 40±10 nm. Phase analysis confirmed an increase in the content of the main phase to 97 % and a decrease in the impurity phase Bi₂Fe₄O₉. The obtained results confirm the efficiency of preliminary solar melting of oxides for the synthesis of high-quality ceramic materials based on BiFeO₃.

Influence of PBTE Addition on the Electric Charge and Heat Transport in AgSbSe₂

A.A. Saddinova — 2026-03-14

The aim of this study is to investigate the influence of PbTe addition on the thermoelectric properties and band parameters of AgSbSe₂ at temperatures below room temperature. For this purpose, the polycrystalline (AgSbSe₂)_x(PbTe)_1-x(x=1; 0.9; 0.85) samples were prepared by direct fusion method. The temperature dependences of electrical conductivity, Seebeck coefficient and thermal conductivity of (AgSbSe₂)_x(PbTe)_1-x (x=1; 0.9; 0.85) samples were investigated in the temperature range 80-350K. The value of electrical conductivity of PbTe added samples decreased compared to AgSbSe₂. Simultaneously, the inversion of the sign of Seebeck coefficient (n→p) in (AgSbSe₂)_x(PbTe)_1-x(x=0.9; 0.85) solid solutions at temperatures of T>110K was observed. It was determined that the effective mass of holes value in (AgSbSe₂)_x(PbTe)_1-x(x=0.9; 0.85) solid solutions increased compared to AgSbSe₂. It has been found that the lattice thermal conductivity of (AgSbSe₂)_x(PbTe)_1-x(x=0.9; 0.85) solid solutions decreases significantly with increasing PbTe amount in AgSbSe₂.

Investigation of the Physical Properties of Yb³⁺ Doped ZnFe₂O₄ Nanopowders Synthesized by Sol-Gel Method

M. Guettaf — 2026-03-14

ZnFe_2-xYb_xO₄ with (x = 0, 0.01, 0.02, 0.03, 0.05, 0.07, and 0.09) have been successfully synthesized by the sol-gel method at 750°C. X-ray diffraction results showed a single phase and crystalline nanopowders of spinel-type structure with cubic symmetry and space group . The lattice parameters increase with Yb³⁺ concentrations. The BET specific area of ZnxFe_2-xYb_xO₄ (x = 0.03) was determined to be the larger 13.59 m²/g. The crystallite size was determined by Rietveld to be in the range of 29-104 nm. FTIR spectra showed two strong absorption bands, a common characteristic of the spinel structure. Further, the shifting of the lower absorption band toward a higher frequency confirms that Yb³⁺ ions predominantly replaced Fe³⁺ ions in octahedral sites. The formation of the spinel phase in the samples was also validated by Raman scattering, with asymmetric broadening, and a systematic shift in the Raman spectra was observed as a function of Yb3+ concentration. Scanning electron microscopy SEM showed that powders consist of micrometric aggregation of smaller particles. EDS examinations verified that the chemical elements Zn, Fe, Yb, and O are present in all samples. The direct bandgap energy values are calculated by Tauc’s plot, and it indicates a semiconductor character of our compound, revealing an increase and enhancement in bandgap energy values from 1.82 to 2.4 eV with Yb³⁺ substitution.

The Enhancing the Yield of Carbon Nanotubes Through the Nanocatalyst-Substrate Interface

Ilyos J. Abdisaidov — 2026-03-14

In this study, the effect of the nanocatalyst/substrate interface on the yield and quality of carbon nanotubes (CNTs) synthesized by chemical vapor deposition (CVD) was investigated. Nickel oxide (NiO) nanoparticles were prepared using the sol–gel spin-coating method and deposited as thin films with different masses (66 mg, 99 mg, and 132 mg) on SiO₂/Si substrates with an identical surface area of 12,56 cm². The NiO nanoparticle thin films on the substrate surface were then placed into a CVD reactor and reduced in a hydrogen atmosphere, resulting in the formation of nickel nanoparticles that acted as active catalysts during CNTs synthesis. Ethanol vapor was used as the sole carbon source without any carrier gas, which enabled precise and comparative evaluation of the CNTs yield. X-ray diffraction (XRD) and Raman spectroscopy were employed to characterize the obtained CNTs. XRD results showed that CNTs with high crystallinity were produced when a 51,7 mg catalyst thin film was used. Raman spectroscopy confirmed the presence of RBM, G, D, and G′ peaks characteristic of CNTs structures. Increasing the catalyst mass led to a rise in RBM frequency and a decrease in CNTs diameter. However, an increase in catalyst mass also caused a reduction in CNTs yield. The highest yield (445%) was observed for Ni nanocatalysts with a mass of 51,7 mg. These findings demonstrate that the thickness of the catalyst layer and its surface distribution density on the substrate play a crucial role in determining the growth efficiency and structural quality of CNTs.

Field Properties of Diode Structures Based on Solid Solution “Silicon-Tin”

Khurshidjon M. Madaminov — 2026-03-14

This article presents the results of studies of the conductivity mechanism in pSi-nSi_1-_δSn_δ (0 ≤ δ ≤ 0.04) structures based on the Si_1-_δSn_δ solid solution with base n-layer thicknesses W ≈ 20-30 μm. The studied samples were obtained in a single technological cycle by the liquid-phase epitaxy method on single-crystal p-Si substrates with the (111) orientation. The results of experimental and computational studies showed that the Poole-Frenkel effect is observed in pSi-nSi_1-_δSn_δ (0 ≤ δ ≤ 0.04) structures at room temperature. This circumstance allows the use of high voltage effects on the parameters of various devices based on the solid solution Si_1-δSn_δ. Thus, there is interest in using this effect in the conversion of thermal energy to electrical energy based on the thermovoltaic effect. Also, the obtained results show the potential of using solid solutions Si_1-δSn_δ (0 ≤ δ ≤ 0.04), grown on silicon substrates, as an active material in thermal energy converters.

Investigation of Physical, Opto-Electronics and Insulating Properties of PPPCC Liquid Crystal Molecule by Density Functional Theory (DFT) Method: A Theoretical Approach

Tikaram — 2026-03-14

In this paper, we have studied the physical, electro-optical and thermal properties of PPPCC liquid crystal molecule. Density functional theory (DFT) with the B3LYP functional and the 6-31G(d,p) basis set is employed for the optimization and analysis of the p-Propoxyphenyl trans-4-pentylcyclohexanecarboxylate (PPPCC) LC molecule. Various physical properties, such as HOMO-LUMO energy levels, electro-optical properties, and global parameters, are computed and analysed for the PPPCC liquid crystal. We have reported the birefringence of p-Propoxyphenyl trans-4-pentylcyclohexanecarboxylate (PPPCC) liquid crystal under the effect of an external electric field. The UV-Visible analysis leaves a strong peak at 252 nm due to π-π* transitions. HOMO-LUMO band gap found to be 5.1 eV. The maximum stretching was observed at 1000 cm^-1 due to the C-O stretching caused by the Ether in the PPPCC liquid crystal. The C-C stretching around 1600 cm^-1is found due to phenyl group present in PPPCC. The temperature-sensitive birefringence value of PPPCC makes it a suitable choice for modern optical technology applications. The refractive index remains unchanged at large applied electric fields, making it a suitable choice for opto-electronic devices in THz applications. Due to the large band gap, this molecule could be a suitable choice for insulating applications.

Modeling of Thermal Effects in a Polyimide Target Under Pulsed Laser Irradiation

J.O. Sadullayev — 2026-03-14

Polyimide is widely valued in modern technology due to its excellent thermal stability and mechanical strength. Understanding how it responds to pulsed laser irradiation is crucial for precise laser-based microfabrication and for interpreting the conditions that can lead to laser induced graphene (LIG) formation. In this study, we use COMSOL Multiphysics to simulate the temperature evolution and heat transfer in a polyimide sample exposed to pulsed laser radiation. The model takes into account temperature dependent thermal properties, laser absorption following the Beer-Lambert law, and the Gaussian energy profile of the laser beam. Our results show how laser fluence and pulse overlap influence heat accumulation within the polymer. While the actual graphene formation process is not modeled here, the thermal analysis provides valuable insight into the photothermal conditions relevant to LIG-related processes.

Photoelectronic Properties of CdGa₂S₄ Single Crystals

Zafar Kadiroglu — 2026-03-14

Experimental investigations of the photoelectric properties of CdGa₂S₄ single crystals were carried out. The study examined the temperature dependence of the photocurrent (within the 110–420 K range), as well as the spectral dependence and transient characteristics of optical quenching at T = 300 K. Optical quenching of the photocurrent was observed within a secondary light beam energy range of 0.6 - 2.49 eV. Measurements revealed energy levels at Ec - 0.21 eV, Ec - 0.42 eV, and Ec - 1.06 eV, as well as sensitizing levels at Ev + 0.89 eV. The decrease in photocurrent at temperatures above 300 K is attributed to thermal quenching. Both optical and thermal quenching of photoconductivity in CdGa₂S₄ crystals are ascribed to changes in the charge state and exchange dynamics of sensitizing and recombination centers.

Photoelectric Properties of ZnₓCd₁-ₓS-Based Photosensitive Semiconductor Structures with Enhanced Ultraviolet Response

R.R. Kabulov — 2026-03-14

The work is devoted to the study of the photoelectric characteristics of an Au-Zn_xCd_1-xS-Mo structured film injection photodetector sensitive in the ultraviolet and visible region of the spectrum of electromagnetic radiation, with maximum sensitivity in the utraviolet region. It has been established that the spectral sensitivity of the Au-Zn_xCd_1-xS-Mo structured film injection photodetector depends on the temperatures on the ZnS and CdS evaporators, which affect the composition of the photoactive layer Zn_xCd_1-xS (x= zn / (Zn + Cd)) in Au-Zn_xCd_1-xS-Mo -structured film injection photodetector. By changing the temperature on the ZnS evaporator, during the growth of the Zn_xCd_1-xS layer, a Zn_xCd_1-xS layer was synthesized on a molybdenum substrate, which served as a photoactive layer for the Au-Zn_xCd_1-xS-Mo photodetector. The created photodetector had sensitivity in the ultraviolet and visible regions of the spectrum of electromagnetic radiation, the maximum value of which was in the ultraviolet region. An analysis of the spectral sensitivity indicates that in the created photodetector the photoactive layer is graded-gap, the band gap of which decreases from E_g = 3.05 eV to E_g = 2.45 eV . A study of light current-voltage characteristics for monochromatic radiation showed that they are characterized by different values of the diode ideality factor ( n) and reverse saturation current (J_o ). The synthesized Zn_xCd_1-xS layer can be used as a buffer layer in thin-film solar cells, such as CdTe, CIGS and others, instead of the CdS layer, which will make it possible to increase both the short-circuit current value and the open-circuit voltage of thin-film solar cells.

Modeling the Temperature and Magnetic Field Dependence of the Band Gap in Narrow-Zone Quantum Well Semiconductors

U.I. Erkaboev — 2026-03-14

The fundamental physical parameter of both bulk and low-dimensional semiconductor structures is the band gap (E^3d_g, E^2d_g), whose energetic width allows the prediction of the operational parameters of semiconductor-based devices in advance. Therefore, the determination of E^3d_gand E^2d_g (in cases where the band gap of newly synthesized materials is not known) is considered one of the primary tasks in semiconductor heterostructure technology. Furthermore, another important feature of E_g is its strong sensitivity to external influences. Indeed, variations in E_g resulting from such effects can fundamentally alter the physical and chemical properties of semiconductor devices.

Optimization of a Vacuum Thermal Evaporation System for the Deposition of Bi–Sb–Te Thin Films

Bunyodjon U. Omonov — 2026-03-14

In this study, thin films based on bismuth and antimony chalcogenides (Bi₂Te₃–Sb₂Te₃) were synthesized using an optimized thermal evaporation vacuum system, and their morphological characteristics were thoroughly investigated. Atomic force microscopy (AFM) results revealed nanoscale granularity on the film surface (in the range of 50–150 nm) and a distinct stepped morphology. Longitudinal profile analyses indicated that the height variations lie within the range of 0.790–0.798 μm. Scanning electron microscopy (SEM) observations confirmed the formation of grains, larger particles, and surface voids, indicating a dual-level morphological structure. Such a structure is critically important for enhancing thermoelectric efficiency by intensifying phonon scattering, thereby reducing thermal conductivity while preserving electron transport properties. The findings demonstrate that Bi₂Te₃–Sb₂Te₃-based thin films possess high scientific and practical potential as thermoelectric materials.

First-Principles Investigation of Electronic and Magnetic Properties in Ga-Doped Silicon Carbide Nanotubes

Vusala Nabi Jafarova — 2026-03-14

This work explores the electronic and magnetic characteristics of gallium (Ga)-doped silicon carbide nanotubes (SiCNTs) through first-principles calculations. Two doping levels (8.3% and 16.6%) are considered, with Ga atoms substituting silicon sites in single-walled (6,0) SiCNTs. Spin-polarized band structure analysis shows that the system transitions from semiconducting at low doping to half-metallic at high doping, suggesting strong potential for spintronic applications. Density of states and Bader charge analyses reveal that Ga incorporation alters charge distribution and orbital interactions, particularly between Ga 5d and carbon 2p states. Magnetic moment calculations indicate that Ga induces localized magnetism primarily on neighboring carbon atoms, with the overall net magnetization increasing with increasing doping level. Energy comparisons between ferromagnetic and antiferromagnetic configurations point to an antiferromagnetic ground state, while formation energy evaluations confirm that Ga substitution at Si sites is thermodynamically favorable. Collectively, these results underscore Ga-doped SiCNTs as promising, tunable materials for future nanoscale electronic and spintronic devices.

Influence of Deformation on Quantum Oscillations in Low-Dimensional Semiconductor

U.Sh. Turdiev — 2026-03-14

In this article, the effect of deformation on the Landau levels of electrons and holes in quantum semiconductors is considered. The effect of deformation on the temperature dependence of quantum oscillation effects in small-sized semiconductors obeying the quadratic dispersion law has been applied. Also, the dependence of the surface density of states on temperature and magnetic field for semiconductor heterostructure materials is theoretically explained. A new analytical expression is proposed to calculate the effect of a magnetic field on the surface density of states at the semiconductor-dielectric interface. A mathematical model is developed to determine the effect of a strong magnetic field on the temperature dependence of the surface density of states in semiconductor heterostructures. As a result, the separation of continuous energy spectra measured at room temperature under the influence of a strong magnetic field into discrete levels at low temperatures is explained on the basis of the proposed model.

Formation of Cu₁₅Si₄/Si Nanophase Films on Silicon Surfaces

K. Dovranov — 2026-03-14

We report on the formation of copper silicide nanofilms using different magnetron sputtering modes. Copper silicide thin films were formed by sputtering Cu onto a Si(111) surface heated to 467^oC in high vacuum using the mid-RFMS method at a frequency of 100 kHz and a D=70% efficiency. The thickness of the resulting heteroepitaxial Cu/Cu₁₅Si₄/Si film was measured using SEM. Also, a Cu₁₅Si₄ film was formed by thermally annealing Cu/Si(111) nanofilms in a vacuum at 800 K for 1.5 hours using the DCMS method. The thickness and surface morphology of the obtained samples were studied using SEM. The formation of silicide films is confirmed by the results of energy-dispersive spectra. The formation of a copper (Cu) silicide film depends on the copper crystal size and substrate temperature, and at 467℃, a 75 nm-thick Cu₁₅Si₄ film was formed under a 130 nm-thick copper layer. These findings provide new insights into the mechanisms governing copper-silicon interface reactions and highlight the potential of copper silicide nanofilms to improve the performance of metal-oxide-semiconductor transistors and high-speed integrated circuits.

Mathematical Modeling of Electrostatic Potential in Radial and Planar p–n Junctions: A Comparative Study

Dildora A. Qalandarova — 2026-03-14

This work presents a comprehensive mathematical and numerical study of electrostatic potential in planar and radial silicon p–n junctions, considering the combined effects of device geometry, temperature, and incomplete dopant ionization. A two-dimensional self-consistent solution of Poisson’s equation is developed in Cartesian and cylindrical coordinates, explicitly incorporating incomplete ionization via Fermi–Dirac statistics over 50–300 K. At 100 K, incomplete ionization reduces effective space-charge density by 38‑45%, increases depletion width by 55–70%, and modifies the built-in potential by up to 42% compared to room-temperature predictions. Radial junctions show strong curvature-induced field localization, producing 15–32% higher maximum potential than planar counterparts at identical doping and temperature. For N = 10²³ m⁻³, maximum potential rises from 1.95 → 2.85 V (planar) and 2.45 → 3.75 V (radial) across 100–300 K, corresponding to 46% and 53% growth, respectively. Peak electric fields reach 3.2×10⁶ V·m⁻¹, with radial junctions exceeding planar values by ~7–12%, consistently showing 25–32% stronger electrostatic confinement. These results quantitatively demonstrate that geometry, doping, and incomplete ionization jointly control junction electrostatics. Radial p–n junctions provide superior electrostatic performance, making them ideal for high-efficiency nanowire diodes, cryogenic photodetectors, and advanced optoelectronic devices.

Cryogenic Material and Electrophysical Changes in Si and GaAs

Jonibek Sh. Abdullayev — 2026-03-14

This study presents a comprehensive investigation of the cryogenic electrical and material behavior of silicon (Si) and gallium arsenide (GaAs) over a wide temperature range from 4 to 300 K and doping concentrations spanning intrinsic conditions up to 1×10¹⁸ cm⁻³. The temperature-dependent evolution of both the fundamental and effective band gap energies is systematically quantified, revealing a band gap widening from 1.12 to 1.17 eV in Si and from 1.42 to 1.51 eV in GaAs as the temperature is reduced from room temperature to 4 K. Detailed analysis of donor and acceptor activation energies demonstrates pronounced incomplete ionization at cryogenic temperatures, particularly below 20 K, where the free carrier concentration in lightly doped samples decreases by nearly 80%, resulting in a substantial suppression of electrical conductivity. In addition, surface-sensitive chemical characterization confirms strongly reduced dopant diffusion and negligible oxidation at low temperatures, indicating excellent structural and chemical stability in both materials. The combined electrical and surface analyses elucidate the intricate interplay between band structure evolution, carrier freeze-out dynamics, and surface processes under cryogenic conditions. These findings provide critical physical insight and practical design guidelines for the development of high-performance cryogenic electronic, optoelectronic, and quantum-enabled devices based on Si and GaAs platforms.

Radiation-Induced Phase Transformations, Point Defect Aggregation, and Nanoparticle Formation in Gamma-Irradiated NaCl Crystals

Shovkat Buzrikov — 2026-03-14

For the first time, the influence of growth Na/Cl non-stoichiometry at the surface of a NaCl single crystal on its phase composition, gamma-irradiation-induced point-defect aggregation in both sublattices, and nanoparticle growth was studied using a combination of experimental methods and modern analytical instruments. It was found that under irradiation with doses <1 MR, the initial impurity nanophases NaClO₃ and Na₂O on the surface are ruptured, and instead Na2Cl, NaCl, NaOH, and metallic Na and NaH are formed.

The Improving Carbon Nanotube Synthesis by the Removal of Amorphous Carbon

Sevarakhon G. Gulomjanova — 2026-03-14

In this study, carbon nanotubes (CNTs) were synthesized on Ni-coated sapphire substrates using conventional and water-assisted chemical vapor deposition (CVD and WA-CVD) methods to evaluate the effect of water vapor on amorphous carbon removal and catalyst activity at low temperatures. Reduced nickel nanocatalysts were prepared by the sol–gel method and activated in a hydrogen atmosphere. Raman spectroscopy confirmed that CNTs synthesized by WA-CVD exhibited a higher degree of graphitization (ID/IG ≈ 1.18) and the absence of amorphous carbon peaks around 794 cm⁻¹, indicating improved purity. X-ray diffraction (XRD) analysis revealed the formation of graphitic carbon (002) and Ni₃C crystalline phases, as well as a rightward shift of the (002) peak to 2θ = 26.2°, suggesting lattice contraction caused by water-vapor-induced stress. Transmission electron microscopy (TEM) images showed that CNTs synthesized under WA-CVD conditions were thinner (17–25 nm), longer (≥ 1 µm), and cleaner than those obtained by conventional CVD, which exhibited thick amorphous carbon coatings. These results demonstrate that the controlled addition of water vapor during CVD suppresses amorphous carbon formation, regenerates catalyst active sites, and significantly enhances CNT crystallinity and morphological uniformity. The findings provide an efficient approach for synthesizing high-purity, well-aligned CNTs suitable for thermal interface materials, nanocomposites, and electronic device applications.

Unveiling Pressure-Driven Transitions in Cs₂AgBiBr₆: Insights from DFT into a Lead-Free Solar Perovskite

Sagita Gupta — 2026-03-14

Using the Vienna Ab initio Simulation Package, we investigate the lead-free double perovskite Cs₂AgBiBr₆. We used first-principles density functional theory under pressures up to 30 GPa. Optimization of the structure proves an obvious cubic symmetry in the ambient environment. However, compression appears to promote transitions to lower-symmetry phases, and we observe that the bulk and Young's moduli increase, followed by a decrease in Poisson's ratio. This implies more stiffness but reduced ductility. It is concluded that, as temperature increases, the Debye temperature rises and the thermal expansion decreases. Thus, higher temperature stability is suggested. The electronic bandgap becomes even thinner. It spans 1.95 eV to 1.12 eV, making it more or less direct, which may enhance its optoelectronic usability. Above 15 GPa, we observe a weak magnetic moment, apparently due to Bi–Ag hybridization, and a higher density of states at the Fermi level. Cs₂AgBiBr₆ combines these characteristics, making it a potential material for pressure-tuned photovoltaics and potentially for magneto-optoelectronic applications.

Development of a Single-Layer TiO₂ Photoanode for Dye-Sensitized Solar Cell (DSSC)

S.S. Sharipbaev — 2026-03-14

Dye-sensitized solar cells (DSSC) are considered a promising low-cost and flexible alternative to conventional silicon-based photovoltaic technologies. This work reports the fabrication and analysis of DSSC based on a single-layer nanostructured TiO₂ photoanode. The proposed cell architecture is simplified by eliminating the conventional double-layer configuration, which reduces fabrication complexity and material consumption. The electrochemical and photovoltaic characteristics of the devices were systematically investigated. The energy conversion efficiency of the developed single-layer design is approximately twice that of a conventional two-layer cell. The performance enhancement is attributed to reduced internal resistance, improved electron transport, and suppressed charge recombination. The results demonstrate the potential of simplified single-layer DSSC architectures for transparent, flexible, and low-cost energy-harvesting applications.

Topological Features of Conductive Network Formation in Metal–Polymer Composites with Varying Filler Particle Sizes

Zafarjon M. Khusanov — 2026-03-14

The topology of the infinite cluster in polymer composites containing micro- and nanoparticles of Ni was investigated, enabling a quantitative evaluation of how the size of conducting particles influences the percolation transition and the structure of the conductive network. The use of nanosized Ni reduces the critical concentration to Vs ≈ 0.105, compared with Vs ≈ 0.21 for microparticles, increases the parameter σ₁ by more than an order of magnitude, and results in a sharper, more localized percolation transition. The cluster structure exhibits pronounced fractal–hierarchical features: the fractal dimension of the backbone is 1.6-1.8 and that of the dangling ends is 1.9-2.1. The cluster density, correlation radius, and topological parameters follow power-law relations typical of three-dimensional percolation (ν = 0.85). At high concentrations of the conducting phase (V ≥ 0.3), the asymptotic conductivity reaches 63 Ω⁻¹·cm⁻¹ in nanocomposites versus 8 Ω⁻¹·cm⁻¹for microparticle-based materials. These findings confirm the high efficiency of Ni nanoparticles in forming an extended, interconnected, and branched conductive network, providing the foundation for next-generation high-conductivity composites.

Thermal Expansion Characteristics of Planar and Radial Si/GaAs p–n Heterojunctions

Jonibek Sh. Abdullayev — 2026-03-14

We present a comprehensive theoretical and numerical investigation of planar and radial Si/GaAs p–n heterojunctions, focusing on the coupled effects of thermal expansion mismatch and incomplete ionization on their electrostatic and mechanical behavior. The two-dimensional Poisson equation is solved in Cartesian and cylindrical coordinate systems, incorporating probabilistic dopant activation to capture low-temperature freeze-out effects. At 100 K, incomplete ionization reduces the built-in potential by up to 40% and expands the depletion width by over 50%, with radial junctions showing 15–25% higher potential due to curvature-induced field enhancement. Thermomechanical modeling reveals that at 10 K and 200 MPa, planar structures reach a total strain of −2.8 × 10⁻³ and stress of ≈280 MPa, whereas radial designs sustain −3.9 × 10⁻³ strain but lower stress (≈234 MPa) due to their reduced elastic modulus. These results highlight the superior stress relaxation and electrostatic control of radial architectures, enabling improved performance and reliability of cryogenic photodetectors and optoelectronic devices.

Room-Temperature Ferromagnetism and Spin Polarization in Silicon Doped with Manganese

Olmas E. Sattarov — 2026-03-14

In this study, we investigate the magnetic properties of silicon doped with manganese via thermal diffusion. The results demonstrate clear evidence of room-temperature ferromagnetism in p-type Si, arising from the spin alignment of Mn atoms and hole-mediated conductivity. Magnetoresistance and hysteresis analyses confirm spin-dependent transport, indicating that carrier-mediated exchange interactions are responsible for the observed magnetic ordering. The combination of atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) confirms the successful incorporation of Mn atoms into the Si lattice without evidence of large secondary precipitates. The hysteresis loops measured at both 150 K and 300 K for the sample processed at T = 1050 °C (ρ = 4.2×10³ Ω·cm) reveal stable ferromagnetic behavior, with coercive fields of 115 Oe and 87 Oe, respectively. These findings open promising perspectives for the development of silicon-based spintronic devices using CMOS-compatible thermal-diffusion technology.

Study of Cathode-Anode Spraying in a Gas Discharge Light-Sensitive System Based on CdTe-SnO2

Sharifa B. Utamuradova — 2026-03-14

This paper investigates the physical phenomena occurring in a gas discharge photosensitive system that uses cathode-anode sputtering. This system consists of a single-crystal cadmium telluride and a glass plate coated with SnO₂, separated by a gas gap. The thickness of the gas gap is 100 µm. The materials under study are sputtered onto the glass plate's surface in a vacuum chamber. Changes in the optical density of bismuth, tellurium, aluminum, and tin under the action of gas discharge are examined. It has been demonstrated that decreasing bismuth thickness results in a sharp increase in the 'current' sensitivity of the gas discharge cell, reaching a value of q_m = 10^‑4 C/cm²at an optical density of D = 0.5.

The Stopping Powers and CSDA Range for Positron and Electron in Human Kidney, Lung and Thyroid Organs

Hawar M. Dlshad — 2026-03-14

This study computed the stopping power of positrons in a few biological tissues in the energy range of 100 eV to 1 MeV. The base of the method is using the modified Bethe-Bloch expression for stopping power and effective atomic number analytical expression including key parameters such as the mean excitation energies of the target atoms that significantly impact stopping power results. Analytical formulas were mostly used to calculate the stopping power and continuous slowing down approximation CSDA range. The calculated results of the stopping power and range for positrons in a few compounds, such as kidney, lung and thyroid tissue are compared with other calculation results like Penelope 2012 program. Monte Carlo simulation was used for the calculations. The results were plotted in graphs to show the contrasts. And they satisfy a recognized need in the medical physics community for tissue-specific positron interaction data, with immediate applications in improving positron emission tomography (PET) image quantification accuracy and refining radiation dose for emitting radiopharmaceuticals.

Deep Learning-Based MRI Denoising Using Noise Statistics Derived from Physical Phantom Measurements

D.G. Sliusarenko — 2026-03-03

High-quality MRI images are essential for accurate definition of target volumes and organs at risk, as well as for correct registration with CT scans when planning radiotherapy. The aim of this work is to develop a robust denoising method that improves visualization of brain structures and preserves anatomical details. A model based on a modified U-Net architecture with residual blocks, attention modules (CBAM) and spatial pyramidal pooling is proposed. The approach is characterized by the integration of statistical noise characteristics obtained from phantom measurements and modeling of degradations in pseudo-k-space (including Gaussian and Rayleigh noise distributions). The validation was performed on 1000 anonymized clinical DICOM images with variable noise levels. The proposed model provided an increase in PSNR by 8–10 dB and an increase in SSIM from 0.72 to 0.97. The edge preservation index (EPI), which reached values of 8.0 on noisy images due to artifacts, stabilized at 1.0 after processing, indicating effective removal of pseudo-contours without blurring true anatomical boundaries. In addition, an average SNR improvement of 7% and a CV reduction of 4–7% were observed on real images, confirming the stability of the method. The combination of physically based noise modeling in the frequency domain and modern deep learning architectures allows for effective noise removal while preserving critical anatomical boundaries. The method has high potential for clinical implementation in radiotherapy planning procedures, in particular to improve the accuracy of MRI/CT fusion.

Numerical Investigation of Heat Transfer Analysis Using Electromagnetohydrodynamics with Aggregated Nanoparticles

Peri K. Kameswaran — 2026-03-14

Optimizing heat transmission remains a significant contemporary challenge in modern technological applications. Nanofluids exhibit strong potential thermal conductivity for enhancing heat transfer and improving energy system efficiency. In comparison to dispersed nanoparticles, aggregated nanoparticles are noteworthy for evaluating the thermal behavior of nanoparticles at the nanoscale. In spite of that aggregation effect, the fractal dimension of the aggregated nanoparticles will have a transformative effect on heat transfer. The objective of the present study is to investigate the influence of electromagnetohydrodynamic effects on heat transfer in a nanofluid containing aggregated nanoparticles over an exponentially stretching sheet. The governing equations for momentum and energy are transformed into a system of nonlinear ordinary differential equations with specified boundary conditions. An analytical solution is presented for a specific instance where the electric field parameter is absent. Numerical solutions are achieved for various ranges of physical parameters, and computed results are validated with existing literature. The findings indicate that nanoparticle aggregation leads to thickening the thermal boundary layer and improving heat transfer. In addition to this synergistic effect of aggregation and electric field, it leads to the decrease in velocity profiles. At 5% volume fraction, aggregated nanoparticles provide a heat transfer
enhancement of approximately 34% over dispersed nanoparticles. The temperature profiles exhibit a rising trend with an increasing volume fraction. In the presence of aggregated nanoparticles, both the skin friction coefficient and the Nusselt number increase with rising magnetic field strength.

Finite Difference Analysis of Prandtl Number and Particle Volume Fraction Effects on Skin Friction and Heat Transfer in Buoyancy Driven Two-Phase Flow with Suspended Particulate Matter (SPM)

Sasanka Sekhar Bishoyi — 2026-03-14

A numerical investigation has been conducted on incompressible, laminar two-phase buoyancy driven flow containing suspended particles around a vertical plate. Despite the relevance of such systems, prior studies have largely overlooked natural convection two-phase flows with particulate matter, particularly concerning the roles of parameters like the Prandtl number and volume fraction. Addressing this research gap is crucial, as these parameters significantly influence flow behavior and heat transfer, which are vital in environmental, industrial, and thermal applications. This study focuses on exploring the effects of volume fraction and Prandtl number on two-phase flow characteristics using an implicit finite difference method applied on a non-uniform grid. The analysis evaluates boundary layer behavior, heat transfer rates, and skin friction coefficients. Streamline patterns are illustrated for different Prandtl number values, while contour topologies are presented to demonstrate the combined influence of the Prandtl number and volume fraction on skin friction and the heat transfer rate. Results show that increasing the volume fraction reduces both the Nusselt number and the skin friction coefficient, while a higher Prandtl number enhances both. The enhanced thermal response observed with higher Prandtl numbers is particularly beneficial in manufacturing processes involving flat wall-like structures that are susceptible to thermal stress. These findings hold practical significance for the design and optimization of heat exchangers, lubrication systems, and thermal management solutions in electronic devices.

A Study on Thermo-Viscous Steady Fluid Motion through a Moving Rectangular Flat Plate – A Numerical Approach

N. Pothanna — 2026-03-14

This study presents a novel numerical approach for analysis on thermo-viscous steady fluid motion over the moving rectangular permeable objects . The numerical results have been found employing Runge-Kutta method of order 6 shooting techniques developed in Mathematica software Numerical differentiation(ND) solve for the flow adaptable equations comprising temperature and velocity. The flow behavior and the impacts of material constraints on the flow region for governed equations of airflow around the aircrafts wings have been analyzed and deliberated taking the help from the generated graphs. The nonlinear coupled Partial differential equations(PDE’s) in terms of temperature and velocity, subject to the corresponding boundary conditions, control the fluid motion. The numerical computations of Runge-Kutta(R-K) 6^th order results are presented in form of tables and also represented for numerous thermo physical coefficient values. The variations of these flow fields have been studied for wide spectrum of physical characteristics which influences the nature of thermo-viscous fluid. The impact of suction/injection parameter, dimensionless viscosity factor, constant pressure and temperature gradients, thermo physical factors and the Prandtl parameter effect on flow region have explored using graphical illustrations with the wide range of values. The Explicit numerical calculations also been calculated and results are associated through the current outcomes in the literature. To improve heat transfer rates in systems such as heat exchangers and aerospace components, engineers can optimize surface textures and flow conditions by taking coefficients effects on flow considerations into account.

FDM Simulation of Cu–Al₂O₃/Water Casson Hybrid Nanofluid Flow and Thermal Transport in a Couette System

Khasim Ali — 2026-03-14

This paper numerically inspects the unsteady Couette Casson hybrid nanofluid (HNF) containing copper (Cu) and aluminum oxide (Al₂O₃) nanoparticles dissolved in water. The upper wall is set in uniform motion, and the lower wall is taken as stationary and stretchable. Finite difference method (FDM) is used to integrate the governed nonlinear partial differential equations. The results are explored through streamlines, isotherms, Nusselt number and skin friction. The impact of key dimensionless numbers such as Grashof number, Biot number, stretching parameter, Casson parameter, and Eckert number on Cu-Al₂O₃-water HNF is discussed. The results disclose that the flow and heat transfer(HT) can be controlled considerably by the key parameters.

Implementation of Harmonic Mapping to a Cloak Phenomenon

Najma Abdul Rehman — 2026-03-14

In this work, a novel physical transformation-based approach has been employed to realize the cloak effect. The transformation mapping is derived for the first time by minimizing the energy functional subject to specified geometric constraints on the scatterer's boundaries. This variational problem has been solved using a physics-informed neural network to solve the boundary-value problem for the Laplace equation. Numerical analysis and graphical visualization of the obtained results clearly demonstrate weak scattering and distortion, as well as negligible perturbation to exterior fields. Furthermore, we show that the proposed mapping achieves considerably improved performance compared with conventional transformation-based cloaking methods, which can be used to mask compact radiating devices, particularly patch antennas.

Optimization of the Optical Properties of Black Silicon Solar Cell

M. Azouza — 2026-03-14

Black silicon (BSi) is an important texturized form of a semiconducting material used in photovoltaic solar cell technology. It is characterized by surface structuration of silicon with very low reflectance. In this paper, we study the optical properties of black silicon in the visible-near infrared wavelength range. Our work focuses on texturing the silicon surface using cryogenic etching in an inductively coupled plasma (ICP) system. The surface structure of black silicon is formed by varying several parameters of the cryo-etching process, like wafer temperature, / ratio and bias voltage. The microstructure surfaces of BSi can be formed in various shapes (Pyramids, Columns, and Cones forms). The optical properties of the micro-structures were studied by spectrophotometer measurements. The results obtained show that columnar microstructures (CMS) exhibit different texturing shapes under different plasma etching process conditions. The CMS obtained without HF chemical treatment process have a reflectance value as high as about 14%. However, the surface reflectance is reduced to less than 2% in the VIS-NIR range by processing the samples in HF solution.

Reduction of Amplitude and Duration of Post-Pulse Oscillations in Bow Tie Active Radiating Antenna

Gennadiy P. Pochanin — 2026-03-05

The paper investigates one of the ways of suppressing post-pulse oscillations in ultra-wideband (UWB) electromagnetic pulses radiated by a bow-tie type antenna excited in active mode (the pulse generator is located directly on the radiator). Since this excitation method does not require balancing or other elements that match the impedances, conditions are created for increasing the radiated power with the same power consumption. To suppress post-pulse oscillations in the radiated field, resistive elements with high resistance are used. They are located near the excitation region in order to absorb the non-radiated part of the excitation signal energy accumulated in the antenna. The influence of the antenna form factor and load resistance on the shape of the radiated signal is experimentally analyzed.

Quantum-Chemical Calculations of Technetium Radiopharmaceuticals

K. Vus — 2026-03-14

The synthesis of radiopharmaceuticals is a major task of nuclear medicine, and Technetium-99m (^99mTc) has ideal nuclear properties for non-invasive nuclear medical diagnostics by single-photon emission computed tomography (SPECT) – a cheaper method than CT, MRI, and PET, suitable for developing countries. Of particular relevance today is the design of various covalently labelled ^99mTc radiopharmaceuticals for the diagnosis and theranostics of oncological diseases. However, the correct selection of ligands and the development of high-quality ^99mTc-based imaging agents that will not disrupt the functions of biologically active molecules requires a good understanding of the coordination chemistry of group 7 transition metals. In this work, the quantum-chemical characteristics of ten ^99mTc radiopharmaceuticals were calculated using ab initio (a combined basis set: SBKJC on the Tc atom and 6-31G (d,p)/DFT – on other atoms, Gamess) and semi-empirical (PM6, MOPAC) methods. Negative (for Tc-Exametazime, Tc-ECD) and positive (for other ^99mTc complexes) values of the Е_LUMO parameter indicated the electrophilic and nucleophilic properties of the radiopharmaceuticals, respectively. Analysis of the absolute hardness values of the complexes revealed that the studied radiopharmaceuticals are soft reagents, with Pertechnetate having the lowest reactivity, which is consistent with the literature data. Dipole moments of most of the ^99mTc radiopharmaceuticals were similar or up to one order of magnitude greater as compared to that of a water molecule. Finally, a strong correlation was established between the ground state dipole moments, lipophilicity and the percentage of nonspecific binding of five radiopharmaceuticals (Tc-Exametazime, Tc-MAG3, Tc-MDP, Tc(III)-DMSA, Tc-DTPA) to plasma proteins (Pearson’s correlation coefficients were ca. -0.719 and 0.611, respectively). The obtained results could be employed for the design of new ^99mTc-based theranostic agents suitable for cancer treatment, in particular those with high nonspecific binding to plasma proteins.

Interactions of Pertechnetate with Proteins: An in-Silico Study

V. Trusova — 2026-03-14

Technetium 99m is a radionuclide extensively used in clinical practice due to a range of its properties among which are short half-life, reduced radiation exposure and toxicity, short labeling time, high target to non-target ratio and low cost. In its highest oxidation state +VII, technetium exists in the form of pertechnetate ([TcO₄]⁻) that serves as an effective imaging agent. One important determinant of pharmacokinetics and bioavailability of pertechnetate involves the possibility of its complexation with blood proteins. In the present work we performed in silico study of the pertechnentate complexes with three blood proteins, deoxyhemoglobin, albumin and transferrin. The molecular docking of [TcO₄]⁻ to the examined proteins provided evidence for pertechnetate localization in the protein structural cavities containing positively charged amino acid residues, with the highest binding affinity being obverved for deoxyhemoglobin. At the same time, the molecular dynamics simulations indicated that, in contrast to deoxyhemoglobin, only the complexes of pertechnetate with plasma proteins albumin and transferrin remain stable and do not show significant variations in root mean square deviation of atomic positions, solvent accessible surface area, radius of gyration and secondary structure per residue. The results obtained may help in better understaning of pertechnetate pharmacokinetic behavior and enhancing its efficiency as an imaging agent.

A Molecular Docking Study of Amyloid-Polysaccharide Composites: I. Interactions with Polyphenols

Valeriya Trusova — 2026-03-14

Filamentous protein aggregates, amyloid fibrils, currently attract considerable interest as a prospective nanomaterial for a variety of biomedical and industrial applications. Among their advantages are biocompatibility, high stability and mechanical strength, self-assembly capability, etc. The integration of other biopolymers such as polysaccharides into amyloid matrix enables creating novel nanomaterials with improved mechanical characteristics and higher loading capacity for biologically active compounds. In the present study we employed the molecular docking technique to ascertain the molecular details of the interactions between the lysozyme amyloid fibrils and a series of polyphenolic compounds including curcumin, gallic acid, salicylic acid, quercetin, resveratrol and sesamin, and to explore the effect of polysaccharide chitosan on such kind of interactions. It was shown that curcumin in enol form has the highest binding affinity for fibrillar lysozyme, while the lowest affinity was observed for salicylic acid. The binding sites for curcumin, gallic acid, quercetin, resveratrol and sesamin appear to occupy the groove on the wet fibril surface, while salicylic acid binds to the dry surface of the fibril. The interfacial amino acid residues in the fibril complexes with polyphenols and chitosan are identified. Chitosan was found to display the ability to interact with polyphenolic compounds within amyloid matrix, resulting in the enhancement of polyphenol binding. The data obtained provide a basis for further designing and experimental testing of the amyloid-chitosan nanocomposites loaded with polyphenols.

Impact of Barium Doping on the Structural and Optical Properties of NiO Thin Films

Mohamed Begui — 2026-03-14

This study investigates the influence of barium (Ba) doping on the structural and optical properties of nickel oxide (NiO) thin films synthesized via spray pyrolysis . NiO films with Ba concentrations of 0%, 2%, 4%, 6%, and 8% were analyzed using XRD, FT-IR, and UV–Vis spectroscopy. XRD results confirmed the formation of cubic NiO with a preferred (111) orientation. Increasing Ba content led to a reduction in peak intensities and the introduction of lattice strain, indicating the insertion of Ba2+ ions into the NiO lattice. Optical measurements showed high transparency of the films in the visible region, while the direct band gap decreased from 3.55 eV to 3.13 eV as the Ba concentration increased. These findings highlight the potential applicability of Ba-doped NiO in various optoelectronic devices.

Influence of Nitrogen Pressure on the Adhesion and Scratch Failure Mechanisms of TiMoN/NbN Multilayer Coatings Deposited by Cathodic ARC PVD

O.V. Maksakova — 2026-03-14

Multilayer nitride coatings are widely used to improve the mechanical performance and durability of engineering components subjected to severe tribological loading. In the present work, the adhesion behaviour and failure mechanisms of nanolayered TiMoN/NbN multilayer coatings deposited by cathodic arc PVD were investigated as a function of nitrogen working pressure. Two coatings were synthesized at nitrogen pressures of 0.52 Pa and 0.13 Pa under otherwise identical deposition conditions. Microscopy analysis revealed that both coatings exhibit a well-defined nanolayered architecture consisting of alternating TiMoN and NbN layers with a modulation period of approximately 85 nm and a total thickness of about 9.5 μm. The decreasing of nitrogen pressure results in a higher density of macroparticles due to the longer mean free path of cathodic arc plasma species. Scratch adhesion tests performed under progressive loading conditions allowed identification of two characteristic failure events corresponding to buckling crack initiation and buckling spallation. The multilayer coating deposited at 0.13 Pa demonstrated slightly improved resistance to crack initiation (5.41 N) compared with the multilayer coating deposited at 0.52 Pa (4.72 N). However, both coatings exhibited similar values of the second critical load (12.4–12.5 N). The multilayer coating deposited at higher nitrogen pressure mainly undergoes adhesive failure with extensive substrate exposure. In contrast, the multilayer coating deposited at lower nitrogen pressure exhibits predominantly cohesive damage within the multilayer structure. The obtained results demonstrate that nitrogen pressure during cathodic arc deposition significantly affects the microstructure evolution and the mechanisms of adhesion failure in TiMoN/NbN multilayer coatings. The study provides insight into the optimization of deposition parameters for improving the mechanical reliability of multilayer nitride coatings.

Comprehensive Analysis of Bianchi Type V Model in f(R,Lm) Theory of Gravity

Prachi Agrawal — 2026-03-14

In this article, a homogenous Bianchi Type V cosmological model has been investigated within the framework of f(R, L_m) gravity. The solution of the field equations has been obtained by considering the special case f(R,Lm)=R/2 + L_mⁿ, where n is free model parameter. The physical as well as the dynamical properties of the model have been analyzed, and graphical representations are provided to illustrate the properties of these parameters.