East European Journal of Physics

Quantum Information and Energy Spectrum of the Ultra Generalized Exponential–Hyperbolic Potential via the Nikiforov–Uvarov Method

Etido P. Inyang, Jonathan E. Osang, Samuel E. Mopta — Mon, 07 Sep 2026 00:00:00 +0000

This study presents a comprehensive investigation of quantum information measures for the one-dimensional Ultra Generalized Exponential–Hyperbolic Potential (UGEHP) within the framework of the Schrödinger equation. Analytical solutions for the energy eigenvalues and corresponding wave functions are obtained using the Nikiforov–Uvarov method. These solutions serve as the basis for evaluating Shannon entropy and Fisher information in both position and momentum spaces. The numerical results show that the total Shannon entropy satisfies the Beckner–Białynicki-Birula–Mycielski (BBM) inequality, while the Fisher information adheres to the Stam–Cramér–Rao bounds, thereby confirming consistency with fundamental quantum uncertainty principles. In addition, the energy spectrum exhibits a pronounced dependence on the screening parameter and quantum numbers, indicating the tunable confinement properties of the potential. The combined analysis establishes a clear connection between energy quantization, wavefunction localization, and information-theoretic measures, offering deeper insight into the effectiveness of the UGEHP model in describing complex quantum systems.

Theoretical Study of the Vibrational Spectrum of the Cesium Dimer Using a Hybrid Interaction Model

Samuel E. Mopta, Victor C. Onuabuchi, Etido P. Inyang — Mon, 07 Sep 2026 00:00:00 +0000

The present study investigates the quantum properties of the cesium dimer (Cs₂) using a hybrid interaction model that combines the Möbius square potential with the screened Kratzer potential (MSSKP). The vibrational energy levels are obtained analytically by solving the Schrödinger equation within the framework of the parametric Nikiforov–Uvarov (pNU) method. The calculated spectra exhibit excellent agreement with available experimental Rydberg–Klein–Rees (RKR) data, demonstrating the validity of the proposed model. Comparative analysis with established potential models, namely the Morse and Manning–Rosen potentials, reveals the superior predictive performance of the MSSKP approach. In particular, the MSSKP model achieves a minimum mean absolute error (MAE) of 0.0234 cm⁻¹, compared with 0.2364 cm⁻¹ and 0.0517 cm⁻¹ for the Morse and Manning–Rosen potentials, respectively. These results highlight the enhanced accuracy and reliability of the MSSKP model in describing the vibrational spectrum of Cs₂. The findings further provide valuable insights into molecular structure, bonding interactions, and quantum behavior, underscoring the potential of the proposed framework for applications in quantum chemistry, molecular spectroscopy, and the theoretical modeling of diatomic molecular systems.

Exact Traveling Waves and Bifurcation Structure of a Coupled Kudryashov-Type Nonlinear Schrödinger System via the Modified Extended Mapping Method

Wafy M. Hasan, Hamdy M. Ahmed, Ahmed M. Ahmed, Haytham M. Rezk, Wafaa B. Rabie — Mon, 07 Sep 2026 00:00:00 +0000

This study obtains exact traveling wave solutions and conducts a bifurcation analysis for the coupled (1+1)-dimensional Kudryashov’s equation. This system of nonlinear Schröodinger-type equations models the simultaneous propagation of optical pulses in a birefringent fiber, incorporating critical higher-order effects like cubic-quartic dispersion and nonlinearities for enhanced physical accuracy. By applying the modified extended mapping method (MEMM), the coupled partial differential equations are systematically reduced to a
manageable ordinary differential equation. This reduction allows for the construction of a broad spectrum of exact solutions such as bright and dark solitons, periodic waves, periodic singular solutions, along with singular solitons, in addition to hyperbolic, exponential, rational, and Weierstrass elliptic function solutions. A key component of the work is a detailed bifurcation analysis of the resulting planar dynamical system. This analysis identifies critical parameter thresholds and classifies all possible qualitative behaviors of the wave solutions, mapping out regions of existence for different solution types. The physical implications of both the derived solutions and the bifurcation structure are discussed in the context of nonlinear optics, particularly for pulse dynamics and stability in dualpolarization optical communication systems. The results demonstrate the efficacy of MEMM and provide new insights that contribute to the understanding and design of advanced optical waveguides.

On the Nuclear Structure and Stellar Weak Rates of Neutron-Rich ¹⁰⁴ˉ¹¹⁶Rh Isotopes

Abdul Kabir, Jameel-Un Nabi, Rahat Badshah, Ayesha Anjum — Mon, 07 Sep 2026 00:00:00 +0000

The nuclear ground state and beta decay properties of neutron-rich odd-odd and odd-A ^104−116Rh isotopes are studied by utilizing the relativistic mean-field (RMF) and proton-neutron quasi-particle random phase approximation (pn-QRPA) models. Potential energy surfaces and potential energy curves are examined to investigate the nuclear deformations, nuclear stability, and shape phase transitions. The Gamow-Teller (GT) strength distributions and β-decay properties are obtained based on a deformed pn-QRPA framework. The computed half-lives and log ft values are in good agreement with existing experimental data, supporting the utilization of nuclear models. Additionally, stellar weak interaction rates are calculated as a function of density and temperature, emphasizing their influence on nucleosynthesis in astrophysical environments. For neutron-rich Rh isotopes, the results provide useful nuclear structural data and reliable inputs for the r-process modeling.

Cosmological Model with Polytropic Bulk Viscosity and Varying Gravitational and Cosmological Constants

Mon, 07 Sep 2026 00:00:00 +0000

This paper investigates Einstein’s field equations within a cosmological model that incorporates a polytropic bulk viscous fluid, with the gravitational and cosmological constants varying in a Bianchi type-I universe. It is observed that different time-dependent scenarios yield variations in physical parameters, which hold significant implications for cosmic evolution. Key physical parameters, including energy density, the gravitational constant, expansion scalar, the cosmological constant, the bulk viscosity coefficient and shear scalar are examined for their physical significance. The geometrical and observational interpretations of the cosmological model are also investigated.

Anisotropic Cosmic Evolution and Statefinder Diagnostics of a Bianchi Type VI0 Universe with Hybrid Scale Factor in f(R, Lm) Gravity

V. R. Patil, A.S. Panurkar, P. A. Bolke — Mon, 07 Sep 2026 00:00:00 +0000

We investigate the dynamics of an anisotropic Bianchi type VI₀ cosmological model within the framework of f(R, L_m) gravity by adopting a curvature–matter coupled form f(R, L_m) = R/2 + L^α_m. A hybrid expansion law a(t) = exp^βt t^γ is employed to describe the cosmic evolution, allowing a smooth transition from an early decelerated phase to a late-time accelerated expansion. The parameter α = 0.4 is chosen to ensure stable and physically viable behavior of the model. The analysis shows that the scale factor and spatial volume increase monotonically with cosmic time, indicating a continuously expanding universe. The deceleration parameter exhibits a transition from positive to negative values and approaches the de Sitter limit at late times. The equation of state parameter evolves from a matter-dominated regime toward the quintessence region and asymptotically approaches ω = −1. The energy density remains positive and decreases with time, while the pressure stays negative throughout the evolution, supporting accelerated expansion. Furthermore, the statefinder diagnostics in the {r, s} and {r, q} planes demonstrate that the model deviates from standard cosmology at intermediate epochs and converges to the ΛCDM fixed points at late times. These results indicate that the proposed model provides a consistent and viable description of dark energy-driven cosmic evolution.

Cosmic Acceleration and Stability of Kaluza-Klein Universe in f (Q, T) Gravity

M.T. Sarode, V.G. Mete, A.S. Nimkar — Mon, 07 Sep 2026 00:00:00 +0000

The f (Q, T) gravity has been used in this research to study Kaluza-Klein universe in presence of macroscopic body. In this theory of gravity, the action contains an arbitrary function f (Q, T) where Q and T respectively denote the non-metricity and the trace of energy momentum tensor. The linear and additive form of f (Q, T) gravity, f (Q, T) =αQ+βT where α and β are arbitrary constants, is taken into account in this work. To achieve a physically viable solution of the field equations, we have considered power law and exponential expansion law. We investigate the evolving character of the universe with physical and geometrical properties within this theoretical framework. To enhance clarity, statefinder diagnostic and EoS parameter are examined, to characterize different phases of the universe. The energy conditions of the models are also analyzed and found to be consistent with recent cosmological observations. Besides, one of our models inherently allows a phantom region for dark energy. Further the models examined in this work are confirmed through stability analysis.

Cosmological Evolution of an Anisotropic Bianchi Type-VI0 Universe with Rényi Holographic Dark Energy

Chandra Rekha Mahanta, Rajashree Mahanta — Mon, 07 Sep 2026 00:00:00 +0000

In this work, we investigate a spatially homogeneous and anisotropic Bianchi type VI₀ cosmological model within the framework of General Relativity by considering a non-interacting mixture of pressureless dark matter and R'enyi holographic dark energy (RHDE), with the Hubble horizon serving as the infrared cutoff. Exact solutions of the Einstein field equations are obtained by adopting the hyperbolic scale factor a(t)=(sinh(βt))^1/n. The model parameters are constrained through a Markov Chain Monte Carlo (MCMC) analysis using 77 Observational Hubble Data (OHD) measurements of the Hubble parameter, yielding the best-fit values H₀=67.9km/s^-1Mpc^-1 and n=1.3. A comparison with the standard ΛCDM model reveals a slightly lower minimum χ² value together with negative values of ΔAIC and ΔBIC, indicating a modest statistical preference for the proposed model. The reconstructed cosmic evolution exhibits a smooth transition from a matter-dominated decelerating phase to the present accelerated epoch, with the transition redshift lying within the observationally favored range 0.5≤z_t≤0.7. Furthermore, the evolution of the matter and RHDE energy densities, dark energy pressure, equation-of-state parameter, anisotropy parameter and skewness parameter demonstrates that the model successfully reproduces the observed late-time accelerated expansion while undergoing a gradual isotropization. Overall, the proposed RHDE model provides a physically consistent and observationally viable framework for describing the late-time evolution of the Universe.

Viscous String Cosmological Model with Electromagnetic Field in Saez Ballester Theory

Mohini R. Ugale, Sagar A. Bhakte — Mon, 07 Sep 2026 00:00:00 +0000

The framework of Saez-Ballester formalism is employed to study Bianchi Type III metrics, which is homogeneous and anisotropic, wherein the energy-momentum tensor is derived from a bulk viscous fluid containing one-dimensional strings embedded within an electromagnetic field. To obtain exact solutions, we utilized the proportionality relation between the expansion and shear scalars, as well as the average scale factor of a special form. In addition to the energy conditions, several dynamical and physical parameters were calculated, and their physical implications on cosmology were examined.

Exploring Bianchi Type-VI0 Viscous Holographic Ricci Dark Energy Cosmological Model in Brans-Dicke Theory of Gravitation

Suryanarayana K.P.S. , Sireesha K.V.S., Sathibabu R. — Mon, 07 Sep 2026 00:00:00 +0000

We investigate a viscous holographic Ricci dark energy (VHRDE) model in Bianchi type (BT) -
VIo spacetime within Brans–Dicke (BD) gravity, incorporating a pressure-less matter component. Assuming
a relationship between metric potentials and a parameterised bulk viscosity coefficient, exact solutions of
the BD field equations are found. The combined effects of anisotropy, Ricci holographic cutoff, and bulk
viscosity yield a dynamical framework that can describe multiple phases of cosmic evolution. We examine the
progression of significant measurements, including the scalar field, energy densities, bulk viscosity, viscous
pressure, equation of state (EoS), expansion variables, and the deceleration parameter, revealing a transition
from a decelerated, matter-dominated epoch to an accelerated, dark-energy-dominated phase. Bulk viscosity
generates effective negative pressure driving acceleration, while the BD scalar field modulates gravitational
coupling. Comparison with previous studies confirms that this model provides a viable mechanism for cosmic
acceleration without requiring a cosmological constant.

Traversable Wormhole Solutions through Decoupling Approach in Rastall Theory

Muhammad Sharif, Malick Sallah, Tayyab Naseer — Mon, 07 Sep 2026 00:00:00 +0000

This paper explores the construction of traversable wormhole solutions in the context of Rastall’s gravity using the extended gravitational decoupling method. Based on the modified field equations of this new theory, we apply the present scheme to incorporate an extra gravitational source, which leads to a fully transformed version of the Schwarzschild solution. By means of an appropriate coordinate transformation, this modified geometry is reinterpreted as a wormhole spacetime. The analysis proceeds by investigating the resulting configuration’s fundamental physical and geometric features, specifically, null energy conditions’ violation, gravitational mass behavior, volume integral quantifier evaluation, and embedding diagram. A key finding is that the wormhole neck arises obviously from the distorted geometry while also satisfying the traversability-required flare-out criterion. Plotting the energy conditions for various Rastall parameter values reveal localized null energy condition violations near the throat, which is consistent with the presence of exotic matter. However, the total exotic matter content is shown to be minimal and highly sensitive to the choice of model parameters. These results underscore the potential of Rastall gravity, in conjunction with gravitational decoupling, to support physically plausible wormhole geometries with reduced exotic matter requirements.

Finite-Size Scaling of Thermal Susceptibility and Specific Heat Density Near the QCD Deconfinement Phase Transition

B. Moussaoui, A. Ait El Djoudi, H. Mouloudj, M.A. Lakehal — Mon, 07 Sep 2026 00:00:00 +0000

The properties of the thermally driven deconfinement phase transition (DPT) from a hadronic gas (HG) to a color-singlet quark-gluon plasma (QGP) containing gluons and massless up and down quarks, at a nonzero quark chemical potential μ, are investigated by considering the volumetric coexistence of the hadronic gas and the QGP in a finite-size system. Finite-size effects are analyzed for the thermally driven DPT at different μ values. The critical exponents are determined using a numerical finite-size scaling (FSS) analysis, by fitting the results as a function of the system size. The effective transition temperature (T_c) exhibits a shift toward higher values as the system size decreases, indicating a critical behavior in the region of the thermally driven DPT from a HG to the QGP. Crucially, all three scaling critical exponents are found to be independent of the quark chemical potential μ, establishing the universality of the finite-size scaling structure with respect to μ.

Finite-Size Scaling Analysis for the QCD Deconfining Phase Transition to a Color-Singlet Quark-Gluon Plasma with the Three u, d, and s Quark Flavors

Amal Ait El Djoudi, Hayet Sahi, Abdelkader Cheddad — Mon, 07 Sep 2026 00:00:00 +0000

In this work, we calculate the partition function of the Quark-Gluon plasma (QGP) projected on the SU(3) color-singlet representation, using the projection method, within a density of states for quarks and gluons given by the Multiple Reflexion Expansion (MRE) approximation. We examine the impact of incorporating the area and curvature terms, in addition to the volume term in the density of states, on the behavior of several physical quantities characterizing the deconfining phase transition from a hadronic gas phase of massive pions, to a Quark-Gluon plasma (QGP) phase made up of gluons, massless up and down quarks, and massive strange quarks along with their antiquarks, within the Bag model and a phenomenological phase coexistence model. By means of a finite-size scaling analysis, we investigate the behavior of some scaling exponents relevant to the occurring deconfining phase transition in a finite volume, especially that of the scaling exponent relative to the shift of the effective transition temperature, by considering contributions of the curvature term only, the area term only in the density of states additionally to the volume term, then the contribution of all three terms, by analyzing the value of the shift critical exponent λ compared to that obtained previously using the volume term only in the quarks and gluons density of states.

Optical Solitons for the Concatenation Model with Differential Group Delay by Lie Symmetry and Kumar Malik Approach

Mon, 07 Sep 2026 00:00:00 +0000

This work examines a generalized concatenation model for birefringent optical fibers and obtains new exact soliton solutions. Using Lie symmetry analysis, the coupled evolution equations are transformed through suitable similarity variables into a manageable system of ordinary differential equations. The resulting reduced system is then treated with the Kumar–Malik method to derive multiple classes of explicit solutions written in Jacobi elliptic, bright soliton, dark soliton, and trigonometric solutions. With appropriate parameter restrictions, these classes simplify to the familiar bright, dark, and periodic soliton waves. To illustrate the physical behavior of the derived structures, representative plots are presented that highlight their propagation features and qualitative stability. Overall, combining symmetry reduction with the Kumar–Malik scheme expands the catalogue of analytical solutions for the concatenation model and deepens understanding of nonlinear pulse dynamics in birefringent media.

Multiform Solitary Wave Structures and Bifurcation Analysis of an Extended Modified (3+1)-Dimensional Kadomtsev–Petviashvili Equation via Hybrid Analytical Approaches

Ibrahim Saber, Hamdy M. Ahmed, Niveen Badra, Islam Samir — Wed, 26 Aug 2026 12:21:05 +0000

This work presents the derivation of exact analytical solutions for a (3+1)-dimensional modified Kadomtsev–Petviashvili equation using two effective analytical schemes, namely the Improved Simple Equation Method and the exponential expansion approach. The considered model is relevant for describing complex nonlinear wave propagation in incompressible fluid environments, where dispersive and nonlinear effects are strongly coupled. The implemented techniques yield a rich variety of wave structures with distinct physical characteristics, including singular and non-singular localized formations, periodic patterns, and exponentially decaying profiles. In addition, hyperbolic and trigonometric configurations are obtained, reflecting different propagation regimes of the system. The qualitative behavior of these solutions is further clarified through three-dimensional surface representations and contour mappings. To ensure the physical admissibility of the obtained solutions, a detailed stability investigation is carried out, highlighting their robustness under perturbations. The findings confirm that the adopted analytical frameworks are highly efficient in constructing diverse nonlinear wave forms and provide deeper insight into the governing mechanisms of multidimensional wave evolution.

Accelerating Five-Dimensional Bianchi Type-I Cosmology in Saez–Ballester Theory with Hyperbolic Expansion

Jagat Daimary, Rajshekhar Roy Baruah — Mon, 07 Sep 2026 00:00:00 +0000

We present a five-dimensional anisotropic Bianchi type-I cosmological model in Saez--Ballester scalar--tensor theory employing the hyperbolic expansion law α(t)=sinh^α(βt). Exact solutions of the field equations are derived and their cosmological behavior is examined. The model evolves from an initial singular state to a late-time accelerated phase, with anisotropy diminishing and isotropization achieved asymptotically. The deceleration parameter approaches (q = - 1), while (ω_de ≈ -1.308) indicates phantom dark-energy behavior. The null, weak, and dominant energy conditions remain satisfied, whereas the strong energy condition is violated, supporting the observed cosmic acceleration. Furthermore, the statefinder and Om diagnostics reveal that the model asymptotically approaches the ΛCDM scenario.

Unified symmetry classification, conservation laws and soliton dynamics for a class of variable-coefficient higher-order nonlinear evolution equations

Suares Clovis Oukouomi Noutchie — Mon, 07 Sep 2026 00:00:00 +0000

Variable-coefficient higher-order nonlinear evolution equations constitute an important class of mathematical models for the description of nonlinear dispersive wave propagation in inhomogeneous media, including shallow water flows, plasmas, optical systems and elastic structures. This paper develops a unified analytical framework for a broad family of such equations incorporating nonlinear convection, third-order dispersion, fifth-order dispersion, BBM-type mixed dispersion and nonlinear dispersive modulation. Admissible equivalence transformations are first constructed and used to reduce the general class, under non-vanishing fifth-order dispersion, to a canonical normalized form. The normalization yields a simplified group-classification problem by establishing an explicit compatibility condition for the temporal component of every admitted Lie point symmetry. Complete Lie symmetry classifications are obtained for the kernel, power-law, exponential and constant-coefficient subclasses, followed by the construction of optimal systems and similarity reductions. Conservation laws are derived from the conservative structure of the governing equation, including a universal mass invariant and a regularized energy conservation law for an important canonical subclass. Furthermore, an exact bright-soliton solution is derived for the constant-coefficient equation, rigorously verified by direct substitution, and employed to validate numerical simulations. The proposed framework unifies equivalence transformations, Lie symmetry analysis, conservation laws, similarity reductions and soliton dynamics within a single parameterized setting, providing a systematic methodology for the analytical investigation of higher-order nonlinear dispersive wave equations.

Particles with Internal Degrees of Freedom

Kostyantyn M. Kulyk, Maryna A. Ratner, Volodymyr V. Yanovsky — Mon, 07 Sep 2026 00:00:00 +0000

A development of a structurally complex particle concept to the case of general interaction potentials between its components is proposed. A structurally complex particle is defined by the restricted problem of N+1 bodies of different masses, which is reduced to the N body problem. Based on the Lagrangian description, a Hamiltonian formalism is formulated and the resulting first integrals of motion are discussed. The absence of equipartition among the degrees of freedom is demonstrated. Using the virial theorem, it is
proved that the energy of internal degrees of freedom does not exceed a certain fraction of the initial energy, depending on the ratio of the masses of internal particles to the mass of the shell. An exactly integrable case of a one-dimensional particle with two internal degrees of freedom is considered. The oscillation frequencies of such a structurally complex particle are determined by their masses and the mass of the shell. The energy distribution over them is not uniform. Universal relations are obtained for the distribution of the kinetic and potential energies of internal particles, which are independent of the choice of initial conditions. These relations provide
more detailed information about the energy distribution than the virial relations.

Emergence of Negative Dispersion of Electromagnetic Waves on a Solid-State Structure Containing a Plasma-Like Medium and Plasmonic Metasurfaces

Yu.O. Averkov, O.Yu. Averkov, N.N. Beletskii — Mon, 07 Sep 2026 00:00:00 +0000

This study provides a detailed theoretical and numerical account of the dispersion properties of p-polarized electromagnetic waves in a complex multilayered solid-state structure. The system under investigation is a six-layer stack featuring two isotropic plasmonic metasurfaces, separated by dielectric spacers and supported by a semi-infinite plasma-like substrate—either a heavily doped semiconductor or a metal. By combining the transfer-matrix formalism with Maxwell’s equations and rigorous boundary conditions, we derive exact dispersion relations for both surface and bulk-surface eigenmodes. Our numerical results point to a cascaded hybridization process between the fundamental metasurface resonances and the surface plasmon-polariton (SPP) modes inherent to the substrate. A particularly significant finding is that adjusting the effective oscillator strengths of the metasurfaces triggers a pronounced dispersion asymmetry. This occurs when one metasurface exhibits a capacitive response while the other becomes effectively inductive. Such an electrodynamic imbalance leads to an anomalous negative frequency dispersion regime characterized by the propagation of backward waves. Furthermore, we demonstrate that modifying the dielectric environment or swapping the semiconductor substrate for a metallic one shifts the regions of resonant interaction, offering a versatile means of controlling the spectral intervals of mode splitting. These findings establish a solid theoretical groundwork for the design of tunable nanophotonic devices and the generation of distributed internal feedback, which is essential for the emergence of absolute electromagnetic wave instabilities in beam-coupled systems.

Gold-Induced Magnetism and Thermal Stability in SiC Nanosheets: A First-Principles DFT+U Study

Mon, 07 Sep 2026 00:00:00 +0000

Gold-doped two-dimensional silicon carbide (SiC) nanosheets are investigated using spin-polarized density functional theory (DFT+U) to examine their electronic structure, induced magnetism, and thermal stability. Single (1Au@Si) and double (2Au@2Si) substitutional configurations are modeled within a 4×4 supercell to ensure reliable evaluation of intrinsic properties. Au incorporation significantly narrows the band gap while preserving the semiconducting character of the SiC nanosheet. Spin-resolved density-of-states analysis shows that Au 5d orbitals dominate the electronic states near the Fermi level. Despite nearly spin-degenerate band dispersions, Mulliken spin population analysis reveals dopant-induced magnetism mediated by neighboring carbon atoms. The 1Au@Si system exhibits a magnetic moment of ~3 μ_B, while the 2Au@2Si configuration stabilizes a ferrimagnetic-like state with a total magnetic moment of ~6 μB. Within the mean-field approximation, the estimated Curie temperature is approximately 510 K, suggesting the possibility of magnetic stability above room temperature and potential applications in spintronic devices.

Thermodynamic and Exergy Analysis of an AP1000-Based Steam Turbine Unit with Optimized Cycle Configuration

Mon, 07 Sep 2026 00:00:00 +0000

According to the strategic importance of Ukraine’s nuclear energy sector modernization, the results of investigation in the development and analysis of the cycle configuration of a steam turbine unit (STU) intended for operation with the AP1000 nuclear reactor are given in the paper. The K-1000-60/1500-2 turbine unit was selected as the reference configuration. Based on this design, a new cycle configuration that includes a combined single-flow high- and intermediate-pressure turbine (HIPT), two low-pressure turbines (LPTs), a steam separator, and a two-stage steam reheating system, was proposed. A thermodynamic and exergy analysis of the proposed STU configurations was performed to evaluate the influence of steam extraction pressures, regenerative feedwater heating parameters, and turbine stage distribution on the cycle performance. Numerical simulation and flow-path calculations of the turbine sections were carried out using modern gas-dynamic design methods. The results show that the optimal selection of steam extraction parameters and intermediate reheating conditions significantly improves the cycle efficiency. The maximum internal efficiency of the STU cycle reached 38.96 %. Exergy analysis demonstrated that the largest exergy destruction occurs in the low-pressure turbine section, while both investigated configurations exhibit high exergy efficiency. A comparative analysis of the turbine stage configurations and axial dimensions of the turbine flow parts was also carried out. The developed approaches can be applied in the design and optimization of next-generation steam turbine units for nuclear power plants.

A High-Sensitivity, Zero-Bias Silicon Photodiode for Detection of Eco-Friendly AgInS2 та CuInS2 Quantum Dot Emission

Mon, 07 Sep 2026 00:00:00 +0000

Silicon p-n photodiodes optimized for detecting a broad spectrum of photoluminescent radiation from AgInS₂ and CuInS₂ quantum dots have been developed and fabricated. By adjusting fabrication parameters and carefully selecting the substrate material, the sensor’s spectral sensitivity peak (0.34 A/W) aligns with the nanocrystal emission range (550–700 nm). To maximize resolution, we operated the detector in zero-bias mode. This minimized dark current to approximately 6 pA, reduced thermal noise, and enabled high detection sensitivity. It has been experimentally established that, with a load resistance of 10 kΩ, the cutoff frequency of the photodiode is 1 MHz and is entirely limited by the RC time constant of the circuit. This frequency response is sufficient not only for steady-state radiometry of colloids and films with a radiation power of 0.29–0.35 mW, but also for precise study of the microsecond kinetics of quantum dot luminescence decay without risking photodegradation.

TCAD-Based Capacitance Analysis for Identifying Longitudinally Localized Oxide-Trapped Charge in SOI FinFETS

Mon, 07 Sep 2026 00:00:00 +0000

This study examines the effect of the spatial position of locally trapped oxide charge on the gate-to-source and gate-to-drain capacitances of an SOI FinFET using three-dimensional TCAD Sentaurus simulations. The results reveal that the location of the trapped charge strongly influences the gate-to-source capacitance via charge-carrier redistribution near the channel surface, whereas a distinct response is observed when the trapped charge is near the oxide edge. Moreover, the gate-drain-to-gate-source capacitance ratio varies systematically with the trapped-charge position along the channel, suggesting that this parameter can serve as a reliable electrical indicator for detecting oxide-trapped charge and estimating its spatial distribution in FinFET devices.

Bidirectional Band Gap Modulation in ZnO-Based Thin Films Via Cation and Anion-Induced Lattice Engineering

Mon, 07 Sep 2026 00:00:00 +0000

Zn₁₋ₓMgₓO and ZnO₁₋ᵧSᵧ thin films were synthesized by ultrasonic spray pyrolysis and investigated to achieve bidirectional band gap engineering in ZnO-based materials. X-ray diffraction confirmed a single-phase wurtzite structure with strong c-axis orientation for all samples. Mg incorporation induced a shift of the (002) peak toward higher angles, indicating lattice contraction, whereas S substitution caused a shift toward lower angles, corresponding to lattice expansion. UV–Vis analysis revealed a systematic blue shift of the band gap with Mg doping (from ~3.26 eV to ~3.33 eV) and a red shift with S incorporation (down to ~3.01 eV). These changes are attributed to lattice deformation and its influence on the electronic structure. Additionally, increased dopant concentration led to reduced crystallite size and increased microstrain and disorder. The results establish a clear correlation between lattice deformation and optical band gap modulation, demonstrating an effective approach for tuning ZnO-based thin films for optoelectronic applications.

Cluster-Induced Ferromagnetism in Manganese-Doped Silicon

Mon, 07 Sep 2026 00:00:00 +0000

The integration of magnetic functionality into silicon remains a key challenge for the development of spintronic devices. In this work, we investigate the structural, electrical, and magnetic properties of Mn-diffused silicon fabricated via a two-step thermal diffusion process that enables controlled incorporation and redistribution of Mn within the Si matrix. Magnetic measurements reveal clear ferromagnetic behavior at room temperature, characterized by a well-defined hysteresis loop with finite coercivity and remanent magnetization. The temperature dependence of magnetization indicates a Curie temperature of approximately 360 K, confirming the stability of magnetic ordering above room temperature. Electrical transport measurements show a systematic evolution of carrier properties with increasing diffusion temperature, including a transition from p-type to n-type conductivity. This behavior is attributed to the activation of Mn-related donor states and defect complexes leading to compensation and overcompensation of boron acceptors. A strong correlation between carrier concentration and magnetic properties is observed, indicating the crucial role of free carriers in mediating magnetic interactions. Based on the combined experimental results, the observed ferromagnetism is attributed to a cluster-induced mechanism, in which Mn-rich regions act as localized magnetic centers coupled via carrier-mediated exchange interactions, consistent with an RKKY-type mechanism. These findings demonstrate that two-step thermal diffusion provides an effective route to tune both the electrical and magnetic properties of silicon, highlighting its potential for silicon-based spintronic applications.

Structural Features of Epitaxial Solid Solution Films (Si2)1-X(GaN)X Grown on Si Substrates

Mon, 07 Sep 2026 00:00:00 +0000

On Si (111) substrates with a diameter of 20 mm, continuous monocrystalline epitaxial layers of (Si₂)_1-x(GaN)_x solid solutions were grown by liquid-phase epitaxy from a limited volume of a tin solution-melt. The grown films had n-type conductivity. An analysis of the X-ray diffraction pattern showed that the grown epitaxial film has (111) crystallographic orientation with evident single-crystal sings. The size of the film subcrystallites is ̴ 40 nm. Due to the replacement of paired Si atoms by a molecule consisting of Ga and N atoms, a slight bending of the film towards the perpendicular to the reflecting surface was observed. Coherently arranged nanocrystals of cubic (c - GaN) and hexagonal (h - GaN) modification of gallium nitride with a crystallite size of L_GaN≈47 nm are formed in the crystal lattice of the epitaxial film.

Radiation-Induced Modification of III–V and II–VI Quantum Heterostructures Under High-Energy X Ray, Gamma-Ray, and Electron Irradiation

Mon, 07 Sep 2026 00:00:00 +0000

Low-dimensional III–V and II–VI quantum heterostructures are important active media for optoelectronic devices operating under radiation environments. In this work, the effects of high-energy X-ray, gamma-ray, and electron irradiation on excitonic recombination and exciton–phonon interaction were investigated in GaAs/AlGaAs and ZnTe/CdZnTe-based quantum heterostructures using low-temperature photoluminescence spectroscopy. The spectra showed pronounced excitonic emission bands accompanied by longitudinal optical phonon replicas, indicating phonon-assisted recombination processes. After irradiation, a substantial reduction in photoluminescence intensity was observed, which was attributed to the formation of radiation-induced non-radiative recombination centers. In ZnTe/CdZnTe structures, electron irradiation produced a slight blue shift (approximately 0.7 meV) of the quantum-well emission, whereas X-ray irradiation resulted in a small red shift (approximately 0.6 meV), suggesting irradiation-dependent modification of exciton localization and defect-related potential fluctuations. A semi-quantitative analysis based on integrated PL intensity ratios, an effective non-radiative recombination parameter, and the Huang–Rhys factor (S≈1–2) was performed to correlate PL quenching, spectral shifts, and LO-phonon replicas with radiation-induced defect formation. The relative changes in excitonic, impurity-related, and phonon-assisted emission bands indicate a redistribution of radiative and non-radiative recombination channels after irradiation. A phenomenological interpretation based on radiative and non-radiative recombination rates and the Huang–Rhys description of LO-phonon replicas was used to discuss the observed spectral changes. The results provide a comparative experimental assessment of irradiation-induced modifications in III–V and II–VI quantum heterostructures and may be useful for evaluating the radiation tolerance of semiconductor optoelectronic structures.

Modelling of Optical and Surface Properties of Aluminum Thin Films Using Spectroscopic Ellipsometry

Kh.N. Ahmadova, S.H. Jabarov, M.A. Musayev, I.F. Yusibova, Sh.N. Aliyeva — Mon, 07 Sep 2026 00:00:00 +0000

In this study, aluminum (Al) thin films deposited on soda lime glass substrates were investigated using spectroscopic ellipsometry with a focus on optical modeling and surface characteristics. The films were fabricated by thermal deposition under controlled vacuum conditions. A multilayer optical model, including Al, native oxide (Al₂O₃), and surface-roughness layers, was developed to accurately fit the experimental ellipsometric data.The analysis was performed in the photon energy range of 0.5–6 eV at multiple incidence angles. The Cauchy and Lorentz dispersion models were applied to represent the dielectric response of the oxide and metallic layers, respectively. The surface roughness was modeled using the effective medium approximation. The obtained results demonstrate that surface morphology and oxide layer formation play a significant role in determining the optical behavior of Al thin films. Variations in surface roughness and interface properties were found to influence the refractive index and extinction coefficient. The developed optical model showed good agreement with experimental data, confirming its reliability in describing complex thin-film systems. These findings highlight the importance of accurate optical modeling for the design and optimization of thin film materials in engineering and optoelectronic applications.

Multifunctional Bulk Metallic Glass: An Ab Initio Study on Pd₃₉Ni₁₀Cu₃₀P₂₁ for Enhanced Mechanical Strength and Optical Shielding

Mon, 07 Sep 2026 00:00:00 +0000

Bulk metallic glasses (BMGs) are a type of solid material with amorphous atomic structures that exhibit favorable mechanical, thermal, and functional properties. This study presents the attributes of the glass, examining first-principles details of the Pd₃₉Ni₁₀Cu₃₀P₂₁ bulk metallic glass structure, its elastic properties, thermodynamics, and electronic–optical performance. Density functional theory calculations were performed for a comparison with the amorphous atomic configuration and energy–volume relation through a third-order Birch–Murnaghan equation of state. The very high bulk modulus of approximately 159 GPa and >6 pressure derivatives demonstrated uniformity, resistance, and strong pressure strengthening. All three elastic moduli, Poisson’s ratio, and Pugh’s criterion are constantly demonstrating ductile mechanical response dependent on shear transformation zone–mediated plasticity. The results of the thermophysical examination show stable anharmonic lattice behavior, a Debye temperature of approximately 395 K, and favorable thermal expansion, indicating good predictability of the thermomechanical response. Electronic studies revealed a very metallic phase with low pseudogap around the Fermi level—mainly the hybridization between transition metal d-states and phosphorus p-states into a stable, amorphous phase. Optical spectra that contain a wide band, excellent reflectivity at low photon energies, and an isotropic optical response are typical of metallic glasses. In conclusion, these results prove Pd₃₉Ni₁₀Cu₃₀P₂₁ as a highly mechanically stable material for progress in various mechanical, optical, and energy applications in a lightweight frame.

Effect of Pressure on the Energy Band Structure of AlAs Using sp3s* Model

Ali A. Mohammed, Mumtaz M.S. Hussien, Abbas Hussein Rostam — Mon, 07 Sep 2026 00:00:00 +0000

We used the sp3s* tight-bonding method as a computational approach to calculate the energy band structure of AlAs crystals in the absence of pressure and analyzed the effect of pressure on the energy band structure under low pressure (1-7) GPa. We used two forms of the Birch-Maugham equation of state (third- and fourth-order) to calculate the changes in the elements of the Hamiltonian matrix resulting from changes in crystal volume and lattice constant. The dispersion relationships for the high-symmetry directions in the first Brillouin zone were found by numerically calculating the Hamiltonian diagonal under pressure. The present computations are performed using a routine written in MATLAB. We found that the effects of both forms of the equation of state on the band structure differ only slightly (by 0.01) at low pressure, as shown in the band structure diagrams. The conduction-band valleys creep downward under low pressure, decreasing both the direct and indirect energy gaps. The results obtained were consistent with other experimental and theoretical results.

Structural and Optical Properties of LiGd1-xLux(WO4)2 Co-Doped with Yb3+/Er3+ Synthesized via Solid State Reaction Method

N. Naimi, B. Rekik, I. Lanez, M. Derbal, L. Benharrat, Z. Bendaoud — Mon, 07 Sep 2026 00:00:00 +0000

Double tungstate materials have been extensively studied and have attracted much attention as solid state lighting hosts. These materials with general formula AB(WO₄)₂ (A: alkali metal and B: trivalent rare earth ion) are widely used for their great optical properties. In this work, Gd³⁺ions were partially substituted with Lu³⁺ ions to synthesize the LiGd_1-xLu_x(WO₄)₂ compounds in order to study the structural, vibrational and optical behaviors of LiGd_1-xLu_x(WO₄)₂ co doped with Yb³⁺ and Er³⁺ ions. Using the solid-state reaction, different concentrations of Lu³⁺ (x=2.5%, 5%, 80%, 90%, and 95%) were selected to synthesize our compounds. These concentrations influence the vibrational characteristics of the W-O bond through both band broadening and a shift in the symmetric stretching mode (ν₁). For the optical properties, green up-conversion under 980 nm excitation and down-conversion under 380 nm excitation of the double tungstate co-doped with Yb³⁺ and Er³⁺ were observed in the range of 530-552 nm. The lifetimes of the ²H_11/2and ⁴S_3/2levels, as well as the effect of Lu³⁺substitution on the green emission of Er³⁺ in these compounds, were compared and discussed.

Synthesis of NH4I-Doped Bi2Te3-Based Thermoelectric Materials in an Inert Gas Atmosphere Using an Automated System

Mon, 07 Sep 2026 00:00:00 +0000

This article presents a comprehensive approach aimed at the full automation of the technology for producing semiconductor thermoelectric materials. The main stages of the technological chain—automatic dosing of high-purity raw materials in precise stoichiometric ratios. The combined use of vacuum at 10⁻³ Torr and an inert gas atmosphere (argon at 1.5 atm), holding at a temperature of 720 °C for 5–6 hours, crystal growth by the zone melting method and the cooling (annealing) regime—are analyzed as a single optimized process. The temperature–time profile, diffusion processes, and cooling dynamics are substantiated on the basis of physical models, including Fick’s law and Newton’s law of cooling. It is shown that real-time control of technological parameters using PLC controllers, SCADA systems, and artificial intelligence algorithms ensures phase homogeneity of the material, reduces defect density, and stabilizes electrophysical parameters. In ammonium iodide–doped Bi2Te3 thermoelement samples, the stability of electrical conductivity, the Seebeck coefficient, and the power factor along the entire sample length confirms the homogeneous distribution of dopant additives and the formation of a high-quality crystal structure. The obtained results demonstrate the high potential of the proposed automated technology for the effective application of Bi2Te3-based materials in low- and medium-temperature thermoelectric devices.

Effect Of Electrolyte Concentration and Discharge Frequency on Ti-6Al-4V Powder Particle Size Distribution Obtained by ECDM

Mon, 07 Sep 2026 00:00:00 +0000

This study investigates the distribution of Ti-6Al-4V alloy powder microparticles used in 3D printing under different discharge frequencies and NaCl electrolyte concentrations. This work analyzed the process of obtaining monodisperse Ti-6Al-4V alloy powders using the ECDM method. The results showed that an optimal NaCl electrolyte concentration of 30 g/L ensures stable plasma channel formation and a narrow particle size distribution. Regression analysis and low standard error values (0.00386–0.00834) confirm the process's high controllability. The effect of frequency on particle size was also investigated: at 3.2 kHz, the minimum average particle size of 16.598 µm was recorded, whereas increasing the frequency to 32 kHz increased particle size to 28.063 µm due to thermal accumulation. The results indicate that at both 3.2 kHz and 32 kHz frequencies, 58.24% to 68.89% of the produced powders fall within the 15–55 µm range required for PBF-LB/M technology. These findings demonstrate the suitability of the obtained powders for additive manufacturing technologies.

XRD Study of Phase Evolution in Electrospun PVDF Nanofibers at Different CNT/β-Ga₂O₃ Ratios

Mon, 07 Sep 2026 00:00:00 +0000

Electrospun poly(vinylidene fluoride) (PVDF)-based nanofibrous mats containing carbon nanotubes (CNTs) and β-Ga₂O₃ nanoparticles were fabricated to investigate composition-dependent phase evolution in the PVDF matrix. Pristine PVDF and composite mats with CNT/β-Ga₂O₃ ratios of 1:1, 1.5:0.5, and 0.5:1.5 wt% were prepared under identical electrospinning conditions using a DMF/acetone solvent system. The crystalline structure and phase composition were studied by X-ray diffraction with Co Kα radiation. The pristine PVDF mat exhibited a multiphase structure composed of α, β, and γ phases. After the incorporation of CNTs and β-Ga₂O₃, clear composition-dependent changes in diffraction peak position and intensity were observed. The 1:1 composition reduced the α-phase contribution and enhanced the γ-phase reflections, while the β phase remained dominant. Increased CNT content favored β-phase development, whereas increased β-Ga₂O₃ content promoted γ-phase formation. The results indicate that CNTs mainly support β-phase stabilization, while β-Ga₂O₃ has a stronger effect on γ-phase evolution and structural rearrangement. These findings show that the crystalline phase balance of electrospun PVDF nanofibers can be effectively tailored by controlled CNT/β-Ga₂O₃ incorporation.

Effects of Adsorption of Submonolayer Cs Coatings on the Electronic Structure and Physical Properties of NiO and MoO₃

Mon, 07 Sep 2026 00:00:00 +0000

Using methods for measuring the dependence of the true secondary electron yield δ on the primary electron energy E_p, as well as Auger-electron and photoelectron spectroscopy, the effects of Cs deposition with thickness θ from 0.2 to 4 monolayers on the composition, valence-electron density of states, and energy-band parameters of NiO and MoO₃ films were studied. It is shown that at θ = 1 monolayer (ML), the largest decrease in the electron affinity χ, the largest increase in the secondary electron yield δ, and the photoelectron quantum yield Y occur. At the same time, the band gap width E_g and the positions of peaks in the valence-electron spectra remain practically unchanged. It was shown for the first time that, for NiO, at θ = 1 ML, the surface electron affinity χ approaches zero. It is found that at θ > 1 ML, changes in the composition, structure, emission, and optical properties of the Cs–NiO system begin to be influenced by the thickness of the Cs film.

Age Determination of Low-Enriched Uranium in Various Physical Forms Using Gamma Spectrometry Methods

Mon, 07 Sep 2026 00:00:00 +0000

This paper presents the research results on the age determination of low-enriched uranium in various physical forms using gamma spectrometry methods. The objects of study were uranium working reference materials (uranium oxide powders, uranium alloys, fuel pellets, and microspherical fuel) with ²³⁵U enrichment levels ranging from 0.47% to 19.75%, developed at the NSC KIPT. Two analytical approaches for uranium age dating were proposed and tested: Approach 1 is based on a broad-energy germanium detector (BEGe3830) and the ²¹⁴Bi/²³⁴U chronometer; this method demonstrated efficiency across a wide range of enrichments, from natural to enriched uranium. Approach 2 utilizes a low-energy detector (GL1015R) and the ²²³Ra/²³⁵U chronometer; it was established that this approach is limited to enriched uranium only. The results for the calculated age and model production dates obtained by both approaches show good agreement. The average measurement uncertainty was approximately 10% with an exposure time of 400,000 s.

Modeling and Optimization Validation of Sb₂2Se₃ Thin Film Solar Cells In SCAPS-1D Software

Mon, 07 Sep 2026 00:00:00 +0000

This analytical essay discusses antimony selenide (Sb₂Se₃) as a potential candidate material to be used as a thin-film photovoltaic absorber. Sb₂Se₃ has provided significant ecological/economic benefits, including large optical absorption, an adjustable band gap of about 1.13 eV, and a lack of toxic elements. A parametric exploration was carried out in the current study based on the platform SCAPS-1D in order to identify ideal layer designs, interfaces, carrier dynamics, and band alignments. This analysis has focused on loss mechanisms which constrain photovoltaic performance in an effort to isolate and come up with strategies to inhibit Shockley-Read-Hall recombination, surface recombination, band-offset differences, and internal diffusion effects. The results provide practical suggestions for minimizing voltage losses, such as minimizing absorber/buffer thicknesses, minimizing acceptor densities, optimizing the conduction band offset as close to zero as possible, and minimizing surface recombination and defect densities.

Influence of Hall Current, Thermal Dispersion and Heat Generation on Kerosene-Based TiO₂ Nanofluid Flow Through a Rotating Porous Channel

Venkateswarlu Malapati, Mohammed Almakki, V.B. Rajakumar Komaravolu — Mon, 07 Sep 2026 00:00:00 +0000

In contrast to heat generation and thermal dispersal, the Hall current and rotation factors of a kerosene-based titanium dioxide nanoliquid discharge across two parallel walls embedded in a porous channel are inspected. Suction and hydromagnetic factors are contemplated. Using appropriate initial and boundary conditions, the perturbation approach can yield a precise analytical solution to the governing equations for the nanofluid velocity, temperature, and concentration. Expressions for the shear stress, mass transfer rate, and heat transfer rate at the plates can be obtained. On the one hand, a graphical representation of the primary and secondary velocities, the nanoliquid temperature, and the species concentration is shown. However, for distinct values of the related flow factors, the numerical estimates of shear stress, mass transfer rate, and heat transfer rate for the walls are presented in tabular form. Because of the solute buoyancy force's contribution, the resulting primary and secondary velocity profiles continuously rise to a high level. The concentration increases in conjunction with increases in heat generation and thermal diffusion characteristics throughout the nanofluid. When the thermal buoyancy force is high enough, the primary and secondary velocity profiles diminish. Hall current and the Darcy parameter raise the primary and secondary skin friction coefficients at the upper wall while decreasing them at the lower wall. However, the primary and secondary skin friction coefficients are affected in opposite ways by thermal buoyancy force and magnetic parameter. Results are compared with existing literature.

The Influence of Joule Heating Effect and Thermal Stratification on MHD Ternary Hybrid Nanofluid in a Porous Medium over a Vertically Stretching Cylinder: A Numerical Investigation

Surajit Dutta, Nitul Kalita, Rupam Shankar Nath, Rudra Kanta Deka — Mon, 07 Sep 2026 00:00:00 +0000

The aspects of flow in a magnetohydrodynamic (MHD) ternary hybrid nanofluid consisting of suspended (Cu), aluminum oxide (Al₂O₃), and titanium dioxide (TiO₂) nanoparticles in water (H₂O) were numerically investigated in this study. The effects of thermal stratification and Joule heating are incorporated by passing the nanofluid through a vertically extending cylinder in a porous medium. By implementing an appropriate transformation, the energy and boundary layer equations are simplified to a nonlinear ODE system. The resulting system is solved using MATLAB's fourth-order accurate bvp4c solver. from MATLAB is employed to solve the altered system. The effects are illustrated graphically the change in velocity and temperature and quantitatively tabulate the changes in friction factor, and heat transfer rate for important values of the dimensionless physical factors related to the problem. Crucial findings show that, hybrid nanofluids outperform nanofluids in terms of thermal conductivity. Temperature and velocity of the ternary hybrid nanofluid are both decreased when the heat stratification factor is present, as compared to the absence of stratification. There is a noticeable increase in the heat transfer rate when the ternary hybrid nanofluid is compared with the hybrid nanofluid, which in turn surpasses that of traditional nanofluids. The acquired results are valuable for applications in geothermal energy extraction, chemical processing, and materials synthesis.

Numerical Investigation of Jeffrey Nanofluid over a Moving Thin Needle with Exothermic Chemical Reaction: A Levenberg-Marquardt Neural Network Approach

R. Krishnakumari, V. Sugunamma, M. Jayachandra Babu, J. Girish Kumar — Mon, 07 Sep 2026 00:00:00 +0000

This study examines the heat and mass transmission properties of a Jeffrey nanofluid traveling across a moving slender needle. The main aim is to examine how essential parameters, such as Hall current, couple stress, activation energy, and thermophoresis, affect the fluid's velocity, temperature, concentration, and corresponding entropy generation. The flow configuration of a slender needle is critically pertinent to practical applications, including the thermal design of microneedles for regulated medication delivery, the aerodynamic profiling of slender structural elements in aerospace engineering, and the optimization of delicate sensor probes. With the aid of suitable similarity transformations, the equations which were meant to describe the problem, were transmuted as a framework with nonlinear ordinary equations, and then solved using the bvp4c solver. A notable discovery is that fluid velocity is hindered by augmented magnetic field strength and coupling stresses, while the temperature profile is improved by elevated viscous dissipation and thermophoresis effects. Moreover, the heat transfer rate at the surface decreases as the thermophoresis parameter increases, whereas the mass transfer rate diminishes with higher activation energy. The study indicates that entropy formation, representing energy loss, increases with heightened viscous dissipation and thermal radiation. It is found that the Sherwood number declines by 24.1% when activation energy rises from 0 to 0.8. It is found that the Nusselt number declines by 26.3% when thermophoresis parameter rises from 0 to 2. It is discovered that the friction factor raises by 2.32% when magnetic field parameter escalates from 0 to 2.

A Modified Runge–Kutta and Compact Spatial Scheme for Darcy Forchheimer Prandtl–Eyring Fluid Flow Over a Riga Plate

Yasir Nawaz, Muhammad Shoaib Arif, Muavia Mansoor, Kamal Abodayeh — Mon, 07 Sep 2026 00:00:00 +0000

A modification of existing third order Runge-Kutta method, is proposed. The scheme is explicit, and its first stage consists of a nonstandard denominator, while the last two stages are the same as those of the Runge-Kutta method. For discretizing space-dependent terms, a compact, high-order scheme is employed. The proposed scheme with spatial discretization is employed to find the stability condition of the proposed scheme. The scheme is applied to a dimensionless model in the form of partial differential equations for the slip flow of a non-Newtonian fluid over a Riga plate with heat and mass transfer. Different types of graphs are obtained using the proposed scheme for velocity, temperature, and concentration profiles. Some of the results obtained by the proposed scheme are compared with those obtained by the numerical solution using the MATLAB PDEPE solver. The scheme is also compared with an existing third-order Runge-Kutta scheme, and it produces more accurate results than the existing scheme at specific time and space step sizes.

Electrothermal Modeling of Self-Heating in Si/GaAs p–n Heterojunctions

Mon, 07 Sep 2026 00:00:00 +0000

This work presents a comprehensive electro-thermal analysis of Si/GaAs heterojunctions, focusing on the coupled effects of self-heating, thermal transport, and junction behavior under varying power and temperature conditions. The developed model reveals strong localization of heat near the heterointerface, where Joule heating (10⁶–10⁸ W·m⁻³) generates significant temperature rises of ΔT ≈ 50–150 K and steep gradients up to 10⁵–10⁶ K·m⁻¹. A transition from weak to highly nonlinear electro-thermal behavior is observed as device temperature increases from ~340 K to ~400 K, with hotspot formation at x ≈ 4 μm. The p-Si/n-GaAs configuration reduces peak temperature by 20–30%, indicating improved thermal performance. Thermal conductivity analysis shows that silicon maintains 3–5× higher conductivity than GaAs over 50–600 K, confirming a strong material mismatch that limits heat dissipation in the GaAs region. Additionally, the built-in potential exhibits pronounced dependence on temperature and doping, decreasing from ~0.5–0.9 eV at low temperature (50–150 K) to ~0.1–0.3 eV at 300 K, and collapsing near 0 eV at ~500 K due to intrinsic carrier effects, while increasing doping (10¹⁴–10¹⁸ cm⁻³) enhances the barrier logarithmically by ~5–6×. The model demonstrates high accuracy (RMSE ≈ 1.5–3.2 K, MAPE < 2.5%, R² ≈ 0.99), validating its predictive capability. Overall, the results highlight that electro-thermal coupling, thermal conductivity mismatch, and temperature-driven barrier degradation critically impact device performance. These findings provide important guidelines for optimizing thermal management, interface design, and doping strategies to ensure reliable operation of Si/GaAs heterostructures in high-power and high-temperature applications.

Ab-initio Investigation of the Physical features of Pt-Co Intermetallic Compounds

Tue, 01 Sep 2026 17:27:08 +0000

This article explores the structural, electronic, mechanical, magnetic, and thermodynamic features of the Pt-Co intermetallic compounds with the help of the FP-LAPW (full-potential linearized augmented plane wave) method in the framework of DFT (density functional theory), as executed through Wien2k code. The negative formation enthalpies and cohesive energies indicate that Pt₃Co (L1₂), PtCo (L1₀) and PtCo₃ (L1₂) are stable in the ferromagnetic (FM) phase. The calculations of the lattice constants and bulk modulus align fit with existing theoretical and experimental values. The resulting electronic band structure establishes the metallic nature and the magnetic character of all three studied compounds. The DOS at Fermi level, electronic specific heat coefficient γ_th, polarization P%, and magnetic moment are determined. The investigation of the elastic and mechanical features illustrates that the selected materials are stable and slightly anisotropic. The Pt₃Co and PtCo₃ materials are inherently ductile and the PtCo is the harder compound. To enhance understanding of these materials, the quasi-harmonic Debye model is applied to scrutinize their thermal features.

Electron States in a Five-Layer Semiconductor Structure. Part 1

Mon, 07 Sep 2026 00:00:00 +0000

Transcendental equations have been obtained to determine the electron energy spectrum in a five-layer semiconductor structure with an energy dip at its center for various energy ranges. It is shown that the presence of this dip leads to an increase in the energy gaps calculated within first-order perturbation theory. It is pointed out that the origin of the energy-level shift is associated with the dependence of the electron Hamiltonian not only on the potential-energy operator but also on the kinetic-energy operator, which depends on the effective masses in each layer of the structure. As has been shown, the modification of the potential profile of a simple well due to the dip should result in a lowering of the level, whereas the difference in kinetic energies for promotes an upward shift of the levels, where is the effective electron mass in the -th layer.

Electron States in Five-Layer Semiconductor Structures. Part 2

Mon, 07 Sep 2026 00:00:00 +0000

Transcendental equations for determining the electron energy spectrum in a five-layer semiconductor structure with a potential barrier located at its center have been derived and analyzed for different energy ranges. It is shown that the origin of the energy-level shift is associated with the dependence of the electron Hamiltonian not only on the potential energy but also on the kinetic energy, which is governed by the effective masses of electrons in each layer of the structure. Changes in the electron energy spectrum of a five-layer semiconductor structure whose layers have different values of physical quantities characterizing the band and geometrical parameters of the sample as a function of temperature have been analyzed.

Fundamental Role of Incomplete Dopant Ionization in Governing Electrostatics and Capacitance Response of n-β-Ga₂O₃/p-Si HeterojunctiONS

Mon, 07 Sep 2026 00:00:00 +0000

Incomplete dopant ionization plays a decisive role in determining the electrostatic behavior and capacitance characteristics of n-type β-Ga₂O₃/p-type Si heterojunctions, particularly under cryogenic operating conditions. In this work, a comprehensive physics-based analytical framework incorporating temperature-dependent dopant activation, band alignment, carrier freeze-out, and mobility degradation is developed to investigate junction electrostatics over the 77–300 K range. The analysis reveals that incomplete ionization significantly modifies carrier distribution, depletion dynamics, and electric-field formation at low temperatures. For moderately doped structures (N_A = N_D = 4×10¹⁷ cm⁻³), freeze-out effects at 100 K reduce forward-bias capacitance by approximately 17%, increase depletion width by nearly 0.10 µm, and suppress the peak electric field by about 0.5 MV/cm. In contrast, heavily doped junctions (N_A = N_D = 1×10¹⁸ cm⁻³) exhibit comparatively weak temperature sensitivity, with electrostatic variations below 5% due to enhanced dopant activation stability. Temperature-dependent Cp–n(V) characteristics demonstrate gradual convergence toward full-ionization behavior above 250–300 K, confirming the transition from partial to near-complete dopant activation. Furthermore, the junction capacitance follows a hyperbolic voltage dependence (C ∝ 1/√ΔV), with strong capacitance compression observed under extreme forward bias. The presented results establish a quantitative understanding of freeze-out-controlled electrostatics in Si/β-Ga₂O₃ heterostructures and provide a predictive foundation for the optimization of cryogenic, high-frequency, and high-voltage ultra-wide-bandgap semiconductor devices.

Geometry-Induced Electric Field Enhancement in Planar and Radial Si/GaAs Heterojunctions Under Incomplete Ionization

Mon, 07 Sep 2026 00:00:00 +0000

This work presents a comprehensive electrostatic and transport analysis of planar and radial Si/GaAs heterojunctions over the cryogenic-to-room-temperature regime (20–300 K) using self-consistent solutions of the Poisson and carrier continuity equations implemented within advanced semiconductor device simulation frameworks. Particular emphasis is placed on the role of incomplete dopant ionization and its coupling with junction geometry in determining electric-field distribution and carrier transport characteristics. The results demonstrate that incomplete ionization significantly alters the electrostatic behavior of the heterojunctions at cryogenic temperatures, whereas its influence progressively diminishes near room temperature due to enhanced dopant activation. For planar heterojunctions under complete ionization, the maximum electric field decreases from approximately 1.55∙10³ V/cm at 20 K to 8.5∙10² V/cm at 300 K. Incorporation of incomplete ionization reduces the peak field by nearly 50–100 V/cm below 50 K, while producing negligible deviations above 200 K. In contrast, radial heterojunctions exhibit pronounced electric-field localization arising from curvature-induced geometric confinement. Under incomplete ionization, the peak electric field remains within 3.2∙10⁴–3.6∙10⁴ V/cm, increasing to 4.2∙10⁴–4.6∙10⁴ V/cm for fully activated dopants, corresponding to a geometry-enhanced field amplification of approximately 28–38%. Carrier transport analysis further reveals strong temperature sensitivity of minority carrier injection, which increases by nearly seven orders of magnitude, from 10² cm^-3 at 50 K to 10⁹cm^-3 at 300 K, whereas majority carrier concentration remains nearly constant at 10¹⁶ cm^-3. The radial architecture additionally produces localized depletion-field enhancement near the cylindrical interface, indicating superior electrostatic confinement compared with conventional planar configurations. These findings establish the coupled influence of geometry, dopant activation, and temperature-dependent transport mechanisms on Si/GaAs heterojunction performance and provide a rigorous framework for the optimization of cryogenic optoelectronic, nanoelectronic, and high-field semiconductor devices.

Theoretical and experimental analysis of Rayleigh–Taylor instability and Marangoni convection in copper foil under laser irradiation

Mon, 07 Sep 2026 00:00:00 +0000

This study investigates the physical phenomena occurring on the surface of copper foil under high-intensity pulsed irradiation of a Nd: YAG laser, (λ = 1064nm, τ = 28ps), with particular focus on plasma formation, Rayleigh–Taylor (RT) instability, and the influence of Marangoni convection on crater morphology. The plasma temperature and electron density are determined using experimental methods through spectral emission lines. These parameters evaluate the pressure gradient in the plasma, temperature variations, and changes in surface tension. The RT instability is modeled based on density contrasts arising under strong pressure differentials, while Marangoni convection is described as a mechanism for surface flow formation driven by temperature gradients. The paper analyzes the interplay between these two instabilities, their role in material redistribution, and their influence on the final geometric shape of the laser-induced crater, supported by theoretical calculations and spectroscopic measurements. The results contribute to a deeper understanding of the complex thermohydrodynamic processes involved in laser ablation.

Photon-Induced Fermi Level Shifts and Energetic Modulation of Resonant States in Double-Barrier Resonant Tunneling Nanostructures

Mon, 07 Sep 2026 00:00:00 +0000

This paper presents a theoretical analysis of quantum tunneling mechanisms under photon energy excitation within the framework of the Landauer–Büttiker formalism. The study considers the effects of photon absorption during resonant tunneling, leading to modifications of the Fermi–Dirac distribution and shifts in the chemical potentials. It is shown that photogeneration processes induced by optical excitation enhance the tunneling probability, cause an energy broadening of the transmission function, and result in a shift of the resonant peak in the current–voltage (I–V) characteristics. Based on the proposed model, a nonlinear dependence of quantum conductance on photon energy is established, and it is theoretically demonstrated that an increase in photon energy leads to enhanced tunneling conductance. The developed approach provides a deeper insight into optically excited quantum transport phenomena and establishes a new theoretical basis for the design of light-controlled transport systems in nanoelectronic devices.

Multi-Field Modulation of Tunneling Current, Differential Resistance and Noise in n⁺–GaAs/AlGaAs Tunnel Diodes

Mon, 07 Sep 2026 00:00:00 +0000

This work presents a theoretical study of differential resistance and noise in tunnel diodes under combined optical, magnetic, and high-frequency electromagnetic fields. The tunneling current is modeled using the Tsu–Esaki approach with WKB approximation, while magnetic field effects are introduced via Landau quantization. Optical excitation leads to quasi-Fermi-level splitting and enhances the tunneling current, thereby modulating and smoothing the negative differential resistance (NDR) region. High-frequency fields further modify the barrier transparency, thereby affecting the device's dynamic behavior. Noise analysis based on shot noise and Fano factor shows that a high signal-to-noise ratio (SNR) can be maintained under external perturbations. A generalized multi-field model for n⁺–GaAs/AlGaAs heterostructures is proposed, demonstrating controllable tunneling dynamics, low noise, and stable operation in the sub-THz range. The results indicate strong potential for applications in high-speed optoelectronics and radiation-resistant space electronics.

Temperature-Driven Phase Evolution and Lattice Strain Dynamics During Ga–Sb Co-Diffusion in Single-Crystal Silicon

Mon, 07 Sep 2026 00:00:00 +0000

This study examines the effect of annealing temperature on the microstructure and lattice dynamics of single-crystal silicon co-diffused with gallium and antimony. Samples were annealed in the 1000–1250°C range for a fixed duration of 10 h and analyzed by SEM imaging, EDS elemental mapping, and Raman spectroscopy. With increasing temperature, the samples show four successive microstructural states: (I) sparse Ga-rich clustering at 1000°C, (II) formation of large GaSb droplets (25–60 µm) at 1100°C, (III) refinement into smaller, faceted precipitates (~5 µm) at 1200°C, and (IV) substantial re-dissolution of the secondary phase, leaving only residual domains of ~1.5 µm, at 1250°C. Raman measurements of the Si optical phonon track this sequence: a small tensile shift (~518–519 cm⁻¹) at 1000 °C, a return to the unstrained position (~520 cm⁻¹) at 1100°C when GaSb droplets accommodate most of the lattice mismatch, and increasing compressive shifts (524–525 cm⁻¹, corresponding to ~0.6% strain) at 1200–1250°C as the GaSb phase redissolves into the matrix. Phonon-confinement analysis of the Raman linewidth further indicates crystalline coherence lengths of 3–5 nm within the micrometer-scale precipitates. Taken together, these results indicate that annealing temperature governs a reproducible sequence of clustering, droplet segregation, precipitate refinement, and re-homogenization in the Ga–Sb–Si system, and that this sequence can be tracked quantitatively through the correlated SEM/EDS and Raman signatures reported here.

Incomplete Ionization Effects in C–V Characteristics of Radial p–n and p-i-n Junction Structures

Mon, 07 Sep 2026 00:00:00 +0000

This work presents a comprehensive numerical investigation of incomplete dopant ionization effects on the capacitance–voltage (C‑V) response of radial p–n and p–i–n junctions fabricated from silicon (Si) and gallium arsenide (GaAs). A self-consistent finite element method (FEM) framework was developed to solve Poisson’s equation while explicitly incorporating temperature-dependent dopant ionization statistics. Simulations were performed for doping concentrations of 2×10¹⁵ cm⁻³ and 2×10¹⁶ cm⁻³ over a wide temperature range of 100–300 K. The results demonstrate a monotonic increase in junction capacitance with both dopant density and temperature, with capacitance variations exceeding 35–60% across the studied temperature interval, depending on material system and geometry. At 100–150 K, incomplete ionization reduces the effective carrier concentration by up to 48% in Si and 41% in GaAs at 2×10¹⁶ cm⁻³, leading to pronounced deviations in the C–V characteristics compared with conventional full-ionization assumptions. In contrast, at 300 K, the ionization efficiency exceeds 97%, rendering incomplete ionization effects negligible. Geometrical dependencies were evaluated for core radii of R = 0.5, 1.0, and 1.5 μm. Furthermore, p–i–n structures with intrinsic layer thicknesses of i = 0.1, 0.3, and 0.5 μm were analyzed at R = 1.5 μm, revealing that increasing the intrinsic region thickness suppresses the impact of incomplete ionization by reducing the space-charge sensitivity to dopant activation, lowering capacitance deviations by more than 30%. Two modeling regimes were systematically compared: (A) full dopant ionization and (B) temperature-dependent incomplete ionization.

Changes in the Optical Properties of Semiconductor Quantum Dots under an External Electric Field

Mon, 07 Sep 2026 00:00:00 +0000

The influence of quantum confinement on the energy spectra of spherical semiconductor quantum dots (QDs) made of CdSe, GaP, and GaAs is investigated using the particle-in-a-spherical-box model. We derive discrete energy levels for electrons and holes, demonstrating that the level spacing increases quadratically as the dot radius decreases (∝1/R²). Analytical expressions for the linear and third-order nonlinear interlevel optical absorption coefficients are obtained via the density-matrix formalism, incorporating intraband relaxation and Stark shifts induced by an external static electric field. Numerical results for GaAs QDs reveal that an applied field of F = 100 kV/cm causes significant spectral broadening and a peak reduction of up to $50\%$ at high optical intensities. Our findings demonstrate that both dot size and external fields provide efficient tuning knobs for QD optical responses, with implications for tunable lasers and electro-optic modulators.

Experimental Characterization of Sol–Gel Spin-Coated Al-Doped ZnO/CdTe Heterojunction Thin Films

Mon, 07 Sep 2026 00:00:00 +0000

Al-doped zinc oxide (AZO) has attracted sustained interest as a low-cost, earth-abundant n-type transparent conducting oxide for solution-processed heterojunction photovoltaics. In the present work, undoped ZnO and AZO (2 mol% Al/Zn) thin films were deposited on p-CdTe by a sol–gel spin-coating route and examined as direct, CdS-free ZnO(AZO)/CdTe heterojunctions – a configuration for which experimental reports remain scarce. The structural, optical, electrical, and morphological responses were investigated by XRD, UV–Vis absorbance spectroscopy with first-derivative band-edge analysis, dark and illuminated J–V measurements with Cheung–Cheung diode-parameter extraction, and SEM. XRD confirmed the coexistence of zinc-blende CdTe and c-axis-oriented wurtzite ZnO, with Scherrer crystallite sizes of 27 ± 5 nm. The derivative absorbance maximum shifted from 3.31 eV (ZnO) to 3.33 eV (AZO). Under illumination, the AZO/CdTe device yielded J_sc ≈ 4.2mA·cm^-2, V_oc ≈ 0.43V, with n ≈ 3.1, R_s ≈ 28 Ω·cm², R_sh ≈ 310 Ω·cm², F_F ≈ 27%, η ≈ 0.49%. SEM revealed a pinhole-free polycrystalline AZO overlayer (30–80 nm grains). The results establish a baseline characterization of buffer-free, solution-processed AZO/CdTe heterojunctions.

Comparative Analysis of Incomplete Ionization Effects in P-SiC/n-Ga₂O₃ and P-GaN/n-Ga₂O₃ Heterojunctions Over 77–400 K

O.A. Sattarova, M.Sh. Ibragimova, A.Kh. Choriev, A. Abdukarimov, Jurabek Kamolov — Mon, 07 Sep 2026 00:00:00 +0000

This study presents a comprehensive comparative investigation of wide-bandgap heterojunctions p-SiC/n-Ga₂O₃ and p-GaN/n-Ga₂O₃, with particular emphasis on the influence of incomplete dopant ionization over the temperature range of 77–400 K. The temperature-dependent bandgap energies of GaN, SiC, and Ga₂O₃ were modeled using the Varshni relation, yielding excellent agreement with reported experimental data, with correlation coefficients (R²) of 0.981, 0.975, and 0.978, respectively. The calculated bandgaps decreased slightly with increasing temperature, varying from 3.51 to 3.40 eV for GaN, 3.33 to 3.25 eV for SiC, and 4.90 to 4.87 eV for Ga₂O₃. Corresponding heterojunction band offsets were determined to be approximately 1.36–1.50 eV for Ga₂O₃/GaN and 1.57‑1.62 eV for Ga₂O₃/SiC, confirming the consistency and reliability of the adopted band-alignment model. Electric-field analysis demonstrated strong thermal robustness in both heterostructures. The maximum electric field reached 3.92 × 10⁵ V/cm for the p-GaN/n-Ga₂O₃ heterojunction and 3.98×10⁵ V/cm for the p-SiC/n-Ga₂O₃ heterojunction at 77 K, while exhibiting less than a 3% variation up to 400 K. In addition, the electric field showed a predictable dependence on doping concentration, increasing from approximately 25 kV/cm to 80 kV/cm as the doping level increased from 2×10¹⁴ to 2×10¹⁶ cm⁻³. At room temperature, the p-GaN/n-Ga₂O₃ heterojunction exhibited slightly higher electric-field strength due to its larger conduction-band offset, whereas the p-SiC/n-Ga₂O₃ structure demonstrated enhanced low-temperature performance attributed to incomplete dopant ionization and the resulting carrier redistribution effects. The results provide new insight into the influence of incomplete dopant ionization on the temperature-dependent behavior of p-SiC/n-Ga₂O₃ and p-GaN/n-Ga₂O₃ heterojunctions, providing a theoretical basis for the design of wide-bandgap power devices. These characteristics highlight the strong potential of Ga₂O₃-based heterojunctions for next-generation high-voltage and high-temperature power electronic applications, including electric-vehicle power converters, aerospace electronics, and harsh-environment industrial systems. Nevertheless, further studies incorporating interface-state effects, breakdown-voltage analysis, leakage-current mechanisms, thermal resistance, and long-term reliability assessments are required to fully evaluate their practical device performance and optimize heterojunction design.

Lateral Photoeffect in Metal–Oxide–Semiconductor Structures Based on Monocrystalline Silicon

Mon, 07 Sep 2026 00:00:00 +0000

This paper presents the fabrication technology and experimental results of the lateral photoeffect (LPE) study in Co/SiO₂/n-Si⟨P, Zn⟩ metal-oxide-semiconductor (MOS) structures. The structures were prepared based on initial n-type silicon samples (ρ=1.05 Ω×cm), thermally annealed samples (ρ=1.07 Ω×cm), and highly Zn-compensated n-type silicon samples with specific resistivities of 5.04 Ω×cm, 156.86 Ω×cm, and 1800 Ω×cm, respectively. According to the experimental results, the dependence of the lateral photovoltage (LPV) magnitude on the distance between the contacts in the fabricated MOS structures exhibits a linear character. It was found that the maximum value of the lateral photovoltage increases significantly with increasing specific electrical resistivity in highly Zn-compensated n-type silicon samples. In particular, for the sample with ρ = 1800 Ω×cm, the maximum LPV reached ±16.83 mV at a distance of ±2.3 mm. This result demonstrates the high sensitivity of the LPE in structures based on highly compensated silicon. The obtained results are in good agreement with the energy band diagrams that consider the influence of deep energy levels associated with zinc atoms at the SiO₂/Si interface and the charge carrier concentration.

Electrical, mechanical and optical properties of polyamide-6 composites with carbon nanotubes under irradiation

Mon, 07 Sep 2026 00:00:00 +0000

The dependence of the degree of crystallinity, the dynamic mechanical modulus, and the shear at frequency of ~1 MHz on the content of nanotubes was investigated for unirradiated PA-6/MWCNT nanocomposites. An increase in the degree of crystallinity and a decrease in these moduli with increasing CNT content were found, which is explained by the fact that CNTs in the polymer matrix act as nucleation centers of the crystalline α-phase, as well as nanoparticles disrupting interatomic bonds in chains and between macromolecules. These nanocomposites were irradiated with electrons E_e ≈ 1.8 MeV and an absorption dose of 10 MRad (100 kGy), 20 MRad (200 kGy). The dependence of electrical conductivity, dynamic mechanical moduli, Raman scattering, and fast photoluminescence emission on the CNT content was measured. Irradiation has been shown to have complex effects on the properties mentioned above. Electrons can contribute to both the destruction of chains and the establishment of the crystalline phase, as well as the healing of damage caused by nanotubes through the recombination of electrons with free radicals. Radiation functionalization often leads to changes in the Raman spectra and the energy structure of electrons within the band gap. These changes are associated with the presence of local states related to the amorphous phase and structural defects. The restructuring of the FL spectra can also be affected, which may impact the formation of the conducting cluster.

Nanoparticles as Probes of the Electron Energy Relaxation Length in a DC Glow Discharge

V. Lisovskiy, S. Dudin, A. Shakhnazarian, S. Rezunenko — Mon, 07 Sep 2026 00:00:00 +0000

A new method is proposed for determining the electron energy relaxation length in a DC glow discharge using nanoparticles as diagnostic probes. The method is based on nanoparticle confinement near the first field reversal point in the negative glow. At this position, a local maximum of the plasma potential forms a shallow potential pit for negatively charged nanoparticles. The position of the field reversal point can therefore be determined from the location of a nanoparticle cloud visualized by laser light scattering. Together with the measured cathode-layer thickness and the known interelectrode distance, this allows the electron energy relaxation length to be estimated using an analytical relation between these quantities. The method was demonstrated experimentally in an acetylene discharge, where nanoparticles are naturally formed by plasma polymerization. The electron energy relaxation length was found to increase, on average, with increasing discharge voltage. The experimentally estimated values were approximately 1.5 times larger than those calculated using an analytical model based on the first Townsend ionization coefficient. The discrepancy may partly result from the assumption of a constant electric field in the cathode layer adopted in the analytical model. The proposed method can also be extended to gases that do not form nanoparticles naturally by introducing preformed nanoparticles or by producing them initially in a suitable gas mixture.

Producing High-Purity Lead by a Comprehensive Refining Method

Olexii P. Shcherban, Olexandr I. Kondrik, Dmytro O. Solopikhin — Mon, 07 Sep 2026 00:00:00 +0000

The thermodynamics of redox reactions of the formation of lead oxide and impurity oxides during filtration in an argon atmosphere and Pb distillation under vacuum (~0.5 Pa) was studied. The strength of impurity oxides relative to lead oxide during oxidizing refining and distillation of lead was estimated by the absolute value of the change in Gibbs free energy. A comprehensive distillation refining process of lead was investigated, which includes the stages, such as filtration (oxidizing refining) in an argon atmosphere and lead purification from non-volatile and volatile impurities by evaporation of the metal in a vacuum with condensation of the vapor into a hot liquid phase (T_cond. ≈ 0.85 T_evap.). Experimental results of the application of a comprehensive process for obtaining high-purity lead of the C000 grade with a total content of majority impurities (in the amount) of 99.9996 mass % are presented.

Electronic Structure and Intermolecular Interactions of the Benzoic Acid–Ethanol Complex: Raman Spectroscopy, DFT, and Molecular Docking Analysis

Mon, 07 Sep 2026 00:00:00 +0000

In this work, we investigated intermolecular interactions in benzoic acid and its ethanol solutions using Raman spectroscopy and quantum-chemical approaches. Analysis of the Raman spectra revealed that adding ethanol induces significant changes in benzoic acid's vibrational spectrum. These changes are primarily due to solvent effects and hydrogen-bond formation and are most pronounced in the vibrational modes corresponding to the carboxyl group. The near-invariance of the aromatic ring confirms the preservation of the structural integrity of the molecule. Theoretical calculations were performed at the DFT level, providing a thorough analysis of the system's electronic structure and energetic characteristics. The molecular electrostatic potential (MEP) surface was used to identify reactive sites within the molecule; the oxygen atoms of the carboxyl group emerged as the principal electron-rich nucleophilic centers, while the –OH group of ethanol played a significant role in hydrogen bond formation. HOMO–LUMO orbital analysis demonstrated a redistribution of electron density during complex formation and an increase in the reactivity of the system. Molecular docking results also confirmed benzoic acid's ability to interact with a biologically active binding site. During the calculations, the molecule adopted a stable conformation within the protein's active site, forming a complex through hydrogen bonds and other weak intermolecular interactions. These findings align with the MEP and electronic structure analyses, showing a close link between the molecule's quantum-chemical properties and its potential biological activity. The investigations reveal the mechanism of intermolecular interactions in the benzoic acid–ethanol system and provide a comprehensive explanation of how these interactions influence the molecule's vibrational properties, electronic structure, and behavior in a biological environment.

Interactions Between Technetium-99m Radiopharmaceuticals and Plasma Proteins: A Molecular Docking Study

V. Trusova, P. Kuznietsov, I. Yakymenko, G. Gorbenko — Mon, 07 Sep 2026 00:00:00 +0000

Technetium-99m (^99mTc) is the most widespread radionuclide with physicochemical characteristics highly suitable for diagnostic nuclear medicine. The radiopharmaceuticals obtained by complexation of ^99mTc with ligating agents or targeting biomolecules are increasingly used for diagnostic purposes in oncology, cardiology, nephrology, neurology and other fields of medical practice. One factor that may influence clinical efficiency of ^99mTc radiotracers involves their interactions with the proteins of human blood plasma. Most studies of such kind of interactions have been focused on albumin, while much less attention was given to other protein components of blood plasma. In the present work the molecular docking technique was employed to evaluate the possibility of association between a series of ^99mTc radiopharmaceuticals and plasma proteins including transthyretin, fibrinogen, alpha1-acid glycoprotein, Fc and Fab fragments of immunoglobulin G. It was found that the investigated ^99mTc compounds (except pertechnetate) form the strongest complexes with alpha1-acid glycoprotein and fibrinogen. The affinities of TcMED, TcDTPA, TcMAG, TcECD, TcDIS and TcMEB for alpha1-acid glycoprotein and fibrinogen appeared to be higher than those for albumin. The structural characteristics of both plasma proteins and ^99mTc radiotracers were demonstrated to determine the amino acid composition of the binding sites. The presence of peptide fragments in the structure of ^99mTc compounds was assumed to markedly increase their affinity for plasma proteins. The results obtained may be helpful for gaining deeper insights into biodistribution pattern of ^99mTc radiopharmaceuticals.

Quantitative Transmission Electron Microscopy Analysis of Amyloid Fibril Morphology

Mon, 07 Sep 2026 00:00:00 +0000

Amyloid fibrils are increasingly regarded as versatile protein-based nanomaterials whose functional properties depend not only on their molecular cross-β architecture but also on their supramolecular morphology. The present study was undertaken to compare the mesoscale organization of albumin, insulin, and lysozyme fibrillar assemblies using quantitative transmission electron microscopy. Representative TEM images were analyzed by a standardized image-processing workflow based on segmentation, skeletonization, orientation analysis, and connected-object morphometry. The resulting descriptors included projected fibril/aggregate area fraction, skeleton length density, apparent junction/crossover and endpoint densities, local width, object density, Feret length, aspect ratio, and orientation anisotropy. Insulin displayed the highest projected area fraction, skeleton length density, object density, endpoint density, and apparent junction/crossover density, indicating a compact and highly fragmented architecture dominated by numerous short rod-like elements. In contrast, lysozyme fibrils exhibited the greatest median Feret length and aspect ratio, consistent with a stronger contribution of longitudinal elongation and the formation of more anisometric structures. Albumin showed an intermediate morphology characterized by comparatively sparse, curvilinear fibrils and lower densities of discrete objects and endpoints. Orientation distributions were broad for all three systems, and the corresponding anisotropy indices remained low, demonstrating predominantly isotropic rather than globally aligned organization. These findings indicate that the three protein systems occupy distinct regimes of amyloid assembly, ranging from fragmentation-dominated architectures to more elongated fibrillar networks. The quantitative framework established here provides a basis for relating amyloid morphology to surface accessibility, connectivity, mechanical behavior, and the design of fibril-based hydrogels, biosensors, drug-delivery platforms, and nanocomposites.

DFT Insights into Structural, Optoelectronic and Thermodynamic Characteristics of Chalcopyrite AgAl(S₁₋ₓSeₓ)₂

Mon, 07 Sep 2026 00:00:00 +0000

In this study, we have investigated the structural, optoelectronic, and thermodynamic properties of the quaternary compound AgAl(S_xSe_1-x)₂. This research employed the FP-LAPW method implemented in the Wien2k program and integrated into the density functional theory (DFT) framework. The generalized gradient approximation (WC-GGA) is used to handle the exchange and correlation potential. We have studied the impact of composition on the formation strength, apparent elastic modulus, and volume of the crystal lattice. According to the data collected, no deviation is noted in the compressibility modulus compared to the LCD law, nor in the lattice constant compared to Vegard's law. The approach of Zunger and his collaborators was used to determine the microscopic source of spatial curvature. Compared to previous theoretical research, the band gap values derived from band structure calculations based on the modified Becke-Johnson (mBJ) potential approximation show notable improvements and align much better with experimental results for ternary compounds. The optical properties indicate that the static dielectric constant ε₁(0) increases with an increase in concentration x, while the optical gap energy decreases simultaneously; meanwhile, the dielectric function exhibits significant anisotropy in the zz direction. The study of the effects of thermal energy on certain macroscopic characteristics was carried out using Debye's quasi-harmonic model. Nevertheless, the alloys examined showed stability at intermediate temperatures ranging from 0 to 800 K.

Stoichiometric Evolution of Multi-Phase Tungsten Nitrides under Variable Gas Flow and Auxiliary Plasma Assistance During Magnetron Sputtering

Mon, 07 Sep 2026 00:00:00 +0000

In this work, the influence of Ar/N₂ gas mixture composition and auxiliary plasma-assisted activation on the structural-phase evolution of tungsten nitride (WN) coatings deposited via planar magnetron sputtering was systematically investigated. The coatings were synthesized using a 100-mm diameter tungsten target under varying reactive gas regimes (from 50% to 10% N₂) and two electrical configurations: an additional biased anode (+200 V) and a standard grounded anode setup. X-ray diffraction coupled with qualitative and quantitative optimization proved that the coatings possess a complex heterophase structure composed of hexagonal hcp-WN and cubic fcc-W₂N phases. It has been established that the persistent dominance of the hcp-WN phase with a highly stable (111) texture acts as a rigid energetically favored framework across all gas flow ratios. Decreasing the nitrogen content primarily affects the secondary, more compliant cubic phase component. At a critical nitrogen deficiency of 10%, the growth of the preferred (200) cubic planes becomes heavily suppressed, forcing the matrix towards grain refinement (nanocrystallization) and stimulating the structural integration of mixed-phase (220)fcc + (102)hcp configuration. Furthermore, shifting to the grounded anode configuration collapses the auxiliary glow discharge zone, dropping the near-substrate plasma density from 7.5 × 10¹⁰ cm⁻³ to 4 × 10¹⁰ cm⁻³. The resulting reduction in adatom surface diffusion length causes rapid thermal quenching, leading to complete texture randomization, a sharp fourfold increase in the isotropic (111)fcc + (100)hcp reflection, and the accumulation of structurally imperfect phase boundaries. The application of an auxiliary biased anode serves as an effective tool to decouple the destructive effects of high-energy ion bombardment from the beneficial structural ordering induced by high-flux, low-energy plasma activation.

Nondestructive Ultrasonic Evaluation of Temperature-Dependent Mechanical and Elastic Properties of PbX (X = S, Se) compounds

Mon, 07 Sep 2026 17:34:06 +0000

A comprehensive investigation of the elastic, mechanical, and thermo-acoustic properties of lead monochalcogenides PbX (X = S, Se) has been carried out along the principal crystallographic directions , and within the temperature range of 0–300 K using ultrasonic nondestructive evaluation method. The second- and third-order elastic constants (SOECs and TOECs) were computed using the Coulomb and Born–Mayer potential frameworks, confirming the elastic stability of the materials under study. Derived mechanical parameters and ultrasonic velocities were obtained from SOECs, indicating brittle mechanical behavior based on the Pugh’s ratio. At 300 K, the Debye temperature, Debye velocity, lattice thermal conductivity, acoustic nonlinearity parameter, and ultrasonic attenuation coefficient were evaluated along the studied orientations. Among all the directions, the orientation exhibited the highest Debye temperature and Debye velocity. The dominant mechanism of ultrasonic attenuation was identified as Akhiezer-type, emphasizing its relevance in thermal dissipation and acoustic damping. The findings suggest that PbSe possesses superior elastic stiffness, whereas PbS exhibits enhanced thermal conductivity and stronger phonon interactions. These characteristics underscore the potential of PbS and PbSe for applications in thermoelectric and ultrasonic sensing technologies.