East European Journal of Physics

Investigation of the Processes of Retention and Release of Implanted Deuterium and Helium Ions for Tungsten and Tantalum Coatings

2024-03-04T14:01:38+00:00

The analysis of main published results of studies of retention and migration of ion-implanted hydrogen isotopes and helium in tungsten and tantalum coatings, formation of radiation damages of the crystal lattice and their interaction with implanted gases, as well as the influence of helium and deuterium on various properties and surface morphology of coatings was carried out. The irradiation of samples was performed by beams of accelerated ions of hydrogen isotopes or He⁺, and in a plasma containing these ions, at various fluences and energies of incident ions, and at various temperatures of targets during implantation. Special attention was paid to the research results obtained at simultaneous irradiation of W both in bulk and in thin-film form. The used methods were electron microscopy, reemission mass spectrometry, thermal desorption spectrometry, X-ray photoelectron spectroscopy, X-ray diffraction, nuclear reaction analysis and Rutherford ion scattering.

Thermally Activated Delayed Fluorescence in Organic Semiconductors and Its Application in Light-Emitting Diodes

2024-03-04T14:01:38+00:00

The presence of the effect of thermally activated delayed fluorescence (TADF) in organic light-emitting materials (emitters), manifested in the "collecting" of triplet excitons in organic semiconductor complexes that do not contain noble metals, creates excellent prerequisites for the application of TADF materials in the technology of manufacturing organic light-emitting diodes (OLED). The significant progress in solving theoretical and technical problems, achieved in the process of development of highly efficient TADF materials, paves the way for the formation of the future of organic electronics. This review presents the analyses of the nature of the long-term fluorescence generation mechanism at the molecular level and the up-to-date strategies for designing TADF donor-acceptor materials, as well as exciplex intermolecular complexes. Special attention is focused on the analysis of TADF emitter ambipolar materials with a highly twisted, rigid molecular structure, which reveal a tendency towards the multi-channel emission mechanisms and their implementation in a variety of OLED structure architectures.

Cosmological Evolution of Bianchi type-VIₒ Kaniadakis Holographic Dark Energy Model

2024-03-04T14:01:35+00:00

The purpose of this paper is to construct anisotropic and spatially homogeneous Bianchi type-VI₀ Kaniadakis holographic dark energy (KHDE) model in general relativity. For this purpose, we consider Hubble horizons as the IR cutoff. To obtain a deterministic solution of the field equations of the model we assume a relationship between the metric potentials which leads to an exponential solution and accelerated expansion. In order to investigate the physical behavior of our dark energy model, we obtain some important cosmological parameters like Hubble, deceleration, equation of state and statefinder as well as ω_khde-ω'_khde, r-s and r-q planes. We also included the stability analysis for the dark energy model through the squared speed of sound. It is observed that the equation of state parameter shows ΛCDM model at late times. Also, the squared speed of sound gives the stability of KHDE model at initial epoch and model is unstable at late times. Statefinder diagnostic and deceleration parameters exhibit a smooth transition of the universe from decelerating phase to current accelerated expansion of the universe and also correspond to the ΛCDM model at late times. All these cosmological parameters support recent observational data.

Barrow Holographic Dark Energy Model in Bianchi Type-III Universe with Quintessence

2024-03-04T14:01:28+00:00

In this paper, we study a spatially homogeneous and anisotropic Bianchi type-III universe containing cold dark matter and Barrow holographic dark energy within the framework of General Relativity. We assume the cold dark matter and Barrow holographic dark energy to be non-interacting and obtain exact solutions of the Einstein field equations by considering a hybrid expansion law and assuming that the expansion scalar is proportional to the shear scalar. We examine the physical and kinematical properties of the resulting model using parameters such as the Hubble parameter, the anisotropic parameter, the deceleration parameter, the equation of state parameter, the jerk parameter etc. We also examine whether the energy conditions are violated or validated. We find that the Null, Weak, and Dominant energy conditions are fulfilled, while the Strong Energy Condition is violated, which supports the accelerated expansion of the universe. The Statefinder diagnostics have been conducted based on recent cosmological observations. In addition, we
reformulated the correspondence between quintessence scalar field and Barrow holographic dark energy model.

Reinterpretation of Friedmann-Robertson-Walker Universe with Variable Gravitational and Cosmological Term in Bouncing Cosmology

2024-03-04T14:01:30+00:00

This paper is devoted to investigate five dimensional homogeneous and isotropic FRW model with varying gravitational and cosmological constant with cosmic time. Exact solution of the Einstein field equations are obtained by using the equation of state p = (γ −1)ρ (gamma law), where γ which is an adiabatic parameter varies continuously as the universe expands. We obtained the solutions for different values of curvature K = 0, 1,−1 by using a(t) = R₀(1 + α²t²)n, where α, n and R₀ are positive constants. Behaviour of the cosmological parameters are presented for different cases of the models. Physical interpretation of the derived model are presented in details. Interestingly the proposed model justified the current cosmological observations with dark energy.

Cosmic Aspects of Sharma-Mittal Holographic Dark Energy Model in Brans-Dicke Theory of Gravity

2024-03-04T14:01:31+00:00

We investigate the cosmological scenario involving spatially homogeneous and anisotropic Bianchi type-V I₀ space-time in the context of the Sharma-Mittal holographic dark energy model within the framework of Brans-Dicke’s theory of gravitation. In order to achieve this objective, the Hubble, deceleration, equation-of-state parameters have been discussed. The deceleration parameter (q) is used to measure the pace at which the expansion of the universe is accelerating. The equation-of-state parameter (ω_smhde) characterizes the quintessence and vacuum areas of the universe. All the parameters demonstrate consistent behaviour following the Planck 2018 data. We assess the dynamical stability by defining the squared speed of sound and examining its behaviour. In addition, the energy conditions and the variation of ω_smhde and ω′_smhde in the model indicate the present accelerating expansion of the universe.

Spectral and Temporal Properties of CXOUJ122956.7+075728 (ULX-1), an Ultraluminous X-Ray Source in NGC 4472

2024-03-04T14:01:30+00:00

This report presents a comprehensive analysis of the spectral and temporal characteristics of a highly significant Ultraluminous X-ray Source (ULX) designated as CXOUJ122956.7+075728 (ULX-1) situated in the elliptical galaxy NGC 4472 within the Virgo cluster. ULX-1 exhibits a soft spectral state, featuring a cool accretion disk component with kT_in ∼ 0.15 keV, accompanied by a power-law tail displaying a steep power-law photon index, Γ ∼ 2.8. The spectral findings strongly support an estimated black hole mass of approximately 3.30 × 10³ M_⊙ under an isotropic emission model, and around 1.47 × 103 M_⊙ in an extreme beaming scenario. Temporally, ULX-1 displays significant variability on time scales of 0.5, 1, and 2 ks, suggesting the possibility of instabilities within the accretion disk contributing to this behavior. However, despite this temporal variability, the power spectra analysis of this soft ULX reveals no signatures of pulsations, distinguishing it from certain pulsating ULXs (PULXs) typically associated with neutron stars. This absence of pulsations in ULX-1 further underscores its unique spectral and temporal characteristics within the broader context of ULX phenomena.

Perfect Fluid with Heat Flow in f(T) Theory of Gravity

2024-03-04T14:01:33+00:00

Bianchi Type-I cosmological models have been a subject of extensive research in cosmology due to their simplicity and relevance in understanding the dynamics of the early Universe. In this study, we investigate the dynamics of such models within the framework of f(T) gravity, an alternative theory of gravity that extends teleparallel gravity by introducing a general function of the torsion scalar, T. We focus on the presence of a perfect fluid with heat flow in the cosmic medium. By solving the field equations of f(T) gravity, we obtain exact solutions for the Bianchi Type-I cosmological models. These solutions provide valuable insights into the evolution of the Universe and how it is influenced by the modified gravity theory. Furthermore, we derive cosmological parameters in terms of redshift, offering a convenient way to interpret observational data and connect theoretical predictions to empirical measurements. Our findings not only contribute to a deeper understanding of the dynamics of Bianchi Type-I cosmological models but also provide a foundation for comparing f(T) gravity with standard general relativity in the context of observational cosmology. This research paves the way for further exploration of alternative gravity theories and their implications for the early Universe’s evolution and structure.

Traversable Wormholes in f(R) Gravity Sourced by a Cloud of Strings

2024-03-05T22:51:15+00:00

Wormhole solutions in General Relativity (GR) require exotic matter sources that violate the null energy condition (NEC), and it is well-known that higher-order modifications of GR and some alternative matter sources can support wormholes. In this study, we explore the possibility of formulating traversable wormholes in f (R) modified gravity, which is perhaps the most widely discussed modification of GR, with two approaches. First, to investigate the effects of geometrical constraints on the global characteristics, we gauge the rr–component of the metric tensor and employ Padè approximation to check whether a well–constrained shape function can be formulated in this manner. We then derive the field equations with a background of string cloud and numerically analyse the energy conditions, stability, and amount of exotic matter in this space-time. Next, as an alternative source in a simple f (R) gravity model, we use the background cloud of strings to estimate the wormhole shape function and analyse the relevant properties of the space-time. These results are then compared with those of wormholes threaded by normal matter in the simple f (R) gravity model considered. The results demonstrate that string cloud is a viable source for wormholes with NEC violations; however, the wormhole space-times in the simple f (R) gravity model considered in this study are unstable.

Bianchi Type-III Viscous Holographic Ricci Dark energy Cosmological model in Brans-Dicke theory of Gravitation

2024-03-04T14:01:34+00:00

This paper investigates and examines a wide range of findings related to the description of holographic Ricci dark energy (HRDE) with the bulk viscosity within Universe's late-time accelerated expansion in the framework of an anisotropic Bianchi type-III cosmological model with pressure-less matter content in the Brans-Dicke theory of gravity. We are using the relationship between the metric potentials to obtain a precise conclusion to the field equations, resulting in a rapid expansion. Several major cosmological parameters, including Hubble, deceleration, matter energy density, Ricci dark energy density (RDE), and Equation of state (EoS), are used to investigate the physical behavior of our dark energy model. We detected some of the viscosity of the holographic Ricci dark energy model using current cosmological observations. We describe how the model's physical and geometric properties are compatible with recent compilations.

Effective Semiclassical Evolution of Bose Einstein Condensates

2024-03-04T14:01:39+00:00

In this work we analyze the effective evolution of a one dimensional Bose-Einstein Condensate (BEC) within a semiclassical description of quantum systems based on expectation values of quantum dispersions and physical observables, known as momentous quantum mechanics. We show that the most prominent features and physical parameters of the system can be determined from the dynamics of the corresponding semiclassical system, consisting of an extended phase space including original classical observables and quantum dispersions, and we also show that particle trajectories for expectation values of observables are a particular characteristic in this framework. We also demonstrate that interactions with several potentials can be implemented in an intuitive way.

Nonclassicalities of the Superposition State of Coherent and Photon-Added-Coherent State

2024-03-04T14:01:29+00:00

The nonclassical properties of the hybrid coherent state (HCS), which is the superposition state of the coherent state and photon-added coherent (PAC) state, is investigated analytically. We evaluated the photon number statistics, the Wigner-Yanase skew information, the Mandel Q factor and the quadrature squeezing of the HCS to quantify its nonclassicality. This superposition state exhibits more nonclassical properties than the PAC state and even the superposition state of coherent state and single-photon-added coherent (SPAC) state. We reported that the addition of more photons to the PAC state part of the HCS generally quantifies more nonclassicalities. The nonclassical properties of the HCS also depend on the amplitudes of coherent state and the PAC state in the HCS.

Thermal Properties and Mass Spectra of Heavy Mesons in the Presence of a Point-Like Defect

2024-03-04T14:01:37+00:00

In this research, the radial Schr¨odinger equation is solved analytically using the Nikiforov-Uvarov method with the Cornell potential. The energy spectrum and the corresponding wave function are obtained in close form. The effect of Topological Defect on the thermal properties and mass spectra of heavy mesons such as charmonium and bottomonium are studied with the obtained energy spectrum. It is found that the presence of the Topological Defect increases the mass spectra and moves the values close to the experimental data. Our results agreed with the experimental data and are seen to be improved when compared with other works.

Effects of Topological Defects and Magnetic Flux on Dissociation Energy of Quarkonium in an Anisotropic Plasma

2024-03-04T14:01:37+00:00

In this paper, we investigate the effects of anisotropic parameters, topological defects, and magnetic flux on the dissociation energy of bottomonium in an anisotropic quark-gluon plasma. We use the three-dimensional Schrödinger equation and derive the energy eigenvalues. Our findings show that the dissociation energy decreases with increasing temperature, but there is a slight shift towards higher values when the magnetic flux is increased. Furthermore, the inclusion of topological defects causes further shifts in the dissociation energy at high temperatures. Additionally, we analyze the impact of anisotropic medium on dissociation energy, both with and without considering topological defects. We observe that including topological defects results in higher values for the dissociation energy across all temperatures, while ignoring them leads to lower values at all temperatures studied. Moreover, we consider the baryonic chemical potential and find that its effect on dissociation is negligible compared to temperature variations. These findings provide valuable insights into the behavior of heavy quarkonium systems under different physical conditions and contribute to our understanding of topological effects in anisotropic media.

Weakly Nonlinear Bio-Thermal Convection in a Porous Media Layer Under Rotation, Gravity Modulation, and Heat Source

2024-03-04T14:01:36+00:00

In this paper, the influence of gravitational modulation on weakly nonlinear biothermal convection in a porous rotating layer is investigated. We consider a layer of porous medium saturated with Newtonian fluid, containing gyrotactic microorganisms, and subject to gravitational modulation, rotation, and internal heating. To analyze linear stability, it is sufficient to represent disturbances in the form of normal modes, while nonlinear analysis includes a truncated Fourier series containing a harmonic of the nonlinear interaction. A six-dimensional nonlinear Lorentz-type model is constructed, exhibiting both reflection symmetry and dissipation. We determined heat and mass transfer using a weakly nonlinear theory based on the representation of a truncated Fourier series. Additionally, the behavior of nonstationary Nusselt and Sherwood numbers was investigated by numerically solving finite amplitude equations. Applying the expansion of regular perturbations in a small parameter to a six-dimensional model of Lorentz equations with periodic coefficients, we obtained the Ginzburg-Landau (GL) equation. This equation describes the evolution of the finite amplitude of the onset of convection. The amplitude of convection in the unmodulated case is determined analytically and serves as a standard for comparison. The study examines the effect of various parameters on the system, including the Vadasz number, modified Rayleigh-Darcy number, Taylor number, cell eccentricity, and modulation parameters such as amplitude and frequency. By varying these parameters, in different cases, we analyzed heat and mass transfer, quantitatively expressed by the Nusselt and Sherwood numbers. It has been established that the modulation amplitude has a significant effect on the enhancement of heat and mass transfer, while the modulation frequency has a decreasing effect.

Importance of Reflected Solar Energy Loaded with SWCNTs-MWCNTs/EG Darcy Porous Stretched Surface: Midrich Scheme

2024-03-04T14:01:35+00:00

Saving energy, shortening processing times, maximizing thermal efficiency, and lengthening the life of industrial equipment are all possible outcomes of heating and cooling optimization. In recent years, there has been a rise in interest regarding the development of high-efficiency thermal systems for the purpose of enhancing heat and mass movement. This study presents an investigation on the non-linear flow of a hybrid nanofluid comprising of Multi Walled Carbon Nanotubes (MWCNTs) and Single Walled Carbon Nanotubes (SWCNTs) over an extended surface, considering the effects of Magnetohydrodynamics (MHD) and porosity, with engine oil serving as the base fluid. Also, radiation and Darcy-Forchheimer flow is considered. The problem of regulating flow is transformed into ordinary differential equations (ODEs) by employing similarity variables. The Midrich Scheme is then used to implement a numerical solution to these equations in the program Maple. Through visual representations of fluid velocities and temperatures, the inquiry addresses several important factors, including magnetic parameters, porosity parameters, radiation parameters, Eckert numbers, inertia coefficients, and Biot numbers. The research has important implications in a number of real-world contexts. Due to its exceptional characteristics, such as reduced erosion, reduced compression drops difficulties, and greatly increased heat transfer rates, hybrid nanofluids are frequently used in heat exchangers. For instance, various cooling devices such as electromagnetic cooling systems, as well as heat exchangers including condensers, boilers, chillers, air conditioners, evaporators, coil preheaters, and radiators. Furthermore, it has the potential to be employed in pharmaceutical businesses and the field of biomedical nanoscience.

Hysteresis and Bistability Bifurcation Induced by Combined Fluid Shear Thickening and Double-Diffusive Convection in Shallow Porous Enclosures Filled with Non-Newtonian Power-Law Fluids

2024-03-04T14:01:31+00:00

This paper presents a numerical study of the linear and non-linear stability of thermosolutal convection within a porous medium saturated by a non-Newtonian binary fluid. The power-law model is utilized for modeling the behavior of the working medium. The given statement implies that the horizontal boundaries experience thermal and solutal flow rates, whereas the vertical walls are impermeable and thermally isolated. The relevant factors that govern the problem being investigated are the Rayleigh number, , the power-law index, , the cavity aspect ratio, , the Lewis number, , and the buoyancy ratio, . An analytical solution is obtained for shallow enclosures ( ) using the parallel flow approximation and a modified form of the Darcy equation. By solving the entire set of governing equations, a numerical investigation of the same phenomenon was conducted. One of the most intriguing discoveries from this research is that it identifies a bi-stability phenomenon, this particular phenomenon signifies the existence of two stable solutions. The results obtained from both methods demonstrate a good level of agreement across a diverse range of these governing parameters.

Effect of Stratification and Joule Heating on MHD Dusty Viscoelastic Fluid Flow Through Inclined Channels in Porous Medium in Presence of Molecular Diffusivity

2024-03-04T14:01:29+00:00

An analysis is carried out to study laminar MHD convection flow of a second order dusty viscoelastic fluid in porous medium through an inclined parallel plate channel in the presence of molecular diffusivity. The plates are maintained at two different temperatures that decay with time. The study is done under the consideration that viscosity and density of the fluid are variable to the extent that it causes stratification and joule heating effect in the process of the flow. The purpose of the study is to examine how stratification and joule heating affect the flow in relation to the physical quantities namely, Stratification factor, Hartmann number, Viscoelastic coefficient, Joule heating parameter, Prandtl number, Eckert number, Schmidt number and Porosity of the medium etc. The non-dimensional governing equations are solved analytically by using regular perturbation technique, and the graphs are plotted using MATLAB programming language. The mathematical expressions for fluid and particle velocity, fluid temperature, fluid concentration, skin friction for fluid and particle, flow flux for fluid and particle, Nusselt number, Sherwood number at the plates are evaluated and their nature of variations for different numerical values of physical parameters are shown graphically, discussed and conclusions are drawn.

A Numerical Study on the MHD Ternary Hybrid Nanofluid (Cu-Al2O3-TiO2/H2O) in presence of Thermal Stratification and Radiation across a Vertically Stretching Cylinder in a Porous Medium

2024-03-04T14:01:31+00:00

The primary objective of this study is to investigate the influence of thermal stratification on the magnetohydrodynamics (MHD) flow of water-based nano, hybrid, and ternary hybrid nanofluids, as they pass a vertically stretching cylinder within a porous media. The nanoparticles Cu, Al₂O₃, and TiO₂ are suspended in a base fluid H₂O, leading to the formation of a ternary hybrid nanofluid (Cu + Al₂O₃ + TiO₂/H₂O). The use of a relevant similarity variable has been utilized to simplify the boundary layer equations which control the flow and transform the coupled nonlinear partial differential equations into a collection of nonlinear ordinary differential equations. The numerical results are calculated with the 3-stage Lobatto IIIa approach, specifically implemented by Bvp4c in MATLAB. This study presents a graphical and numerical analysis of the effects of various non-dimensional parameters, such as the Prandtl number, radiation parameter, heat source/sink parameter, magnetic parameter, porosity parameter, curvature parameter, thermal stratification parameter, and thermal buoyancy parameter, on the velocity, temperature, skin-friction coefficient, and Nusselt number. The impacts of these parameters are visually depicted through graphs and quantitatively represented in tables. The ternary hybrid nanofluid has a higher heat transfer rate than the hybrid nanofluid, and the hybrid nanofluids has a higher heat transfer rate than ordinary nanofluids.

Casson Fluid Flow Past a Shrinking Surface with Heat and Mass Transfers

2024-03-04T14:01:34+00:00

In this study, we have numerically investigated the heat and mass transfers behaviour of Casson fluid flow past a porous shrinking sheet in existence of a magnetic field, thermal radiation, and suction or blowing at the surface. Applying suitable similarity transformations, the leading partial nonlinear differential equations of mass, flow, and heat transfer are converted into solvable ordinary differential equations, which can then be solved numerically with the help of the MATLAB bvp4c scheme. We have analyzed and shown graphically the implications of several non-dimensional controlling factors on the profiles of temperature, concentration, and velocity. Additionally, the Sherwood, Nusselt, and Skin friction for Casson fluids are examined and tabulated. The current study's findings for Casson fluid exhibit great consistency with previous research under specific circumstances.

A Comparative Study on MHD Forced Convective Flow of Different Nanofluids with Water (H2O) as Base Fluid in a Vertical Rectangular Duct

2024-03-04T14:01:33+00:00

In this paper, a comparative study on MHD forced convective flow for heat transfer efficiency of different nanofluids with water (H₂O) as base fluid has been carried out. Here, in this study flow through vertical rectangular has been considered in presence of strong magnetic field. In this laminar flow we consider duct walls as electrically non-conducting where the transverse magnetic field acting normally on the duct walls. Joule heat and the viscous dissipation effects are included in the energy equation and furthermore the walls of the duct are kept at constant temperature. An explicit finite difference method has been adopted with fine grid in the control volume for solving the governing equations of this MHD nanofluid flow. Computational processes are carried out using MATLAB code. In this present work we have plotted the flow fields velocity, induced magnetic field, and temperature for various values of MHD flow parameters graphically by varing thermal Grashof number (G_r), Hartmann number (H_a), Reynold number (R_e), Eckert number (E_c), Prandtl number (P_r), magnetic Reynold number (R_m), and nanoparticle volume fraction (ϕ) respectively.

Effect of Induced Magnetic Field on MHD Flow Between Two Parallel Porous Plates at Constant Temperature Gradient in Presence of Inclined Magnetic Field

2024-03-04T14:01:32+00:00

The paper studies effect of induced magnetic field on laminar convection flow of a viscous electrically conducting incompressible fluid between two parallel porous plates at constant temperature gradient in presence of a uniform inclined magnetic field. An angle (θ) is formed with the vertical line by applying a magnetic field in that direction and field is strong enough to induce another field along the line of flow. Using the proper similarity transformations, the flow equations are converted into ordinary differential equations, which are then numerically solved by using MATLAB's bvp4c solver. Plotting of the graphs allows one to examine the effects of several critical parameters such as Hartmann number, Darcy number, Magnetic Reynolds number, Prandtl number, and Field inclination on velocity field, induced magnetic field, temperature field at the plates. The acquired results demonstrate that the flow system is effectively influenced by the field inclination, the magnetic parameter, and the plate porosity. The rise in field inclination leads to an increase in magnetic drag force.

Heat And Mass Transfer on Flow Past an Accelerated Plate Through Porous Medium with Variable Temperature and Mass Diffusion in Presence of Heat Source/Sink

2024-03-04T14:01:30+00:00

A study to look at how heat and mass transfer affect unsteady MHD flow across an accelerated plate with changing temperature and mass diffusion in the appearance of a heat source (or sink) through a porous medium is presented. Initially, the temperature and concentration of the fluid and plate are considered to be the same at t′ ≤ 0. At t′ > 0, an impulsive uniform acceleration A is applied to the plate in a vertical upward direction. The non-dimensionalised governing equations defining the flow problem are solved using Laplace transform approach. Effect of various physical quantities involved in the velocity, concentration, temperature, the rate of heat transfer and also the rate of mass transfer are investigated through graphs and tables and discussed.

La0.8Bi0.2FeO3 Perovskite-Type: High-Performance of Photocatalytic Degradation of Ortho-Toluidine Blue Under Visible Light Irradiation

2024-03-04T14:01:29+00:00

In this study, La_1-xBi_xFeO₃ (x=0.0, 0.2, 0.4, and 0.6) perovskite nanoparticles were synthesized by a modified Pechini method. Rigorous analysis through XRD and SEM/EDX confirmed the absence of secondary phases in both pure and Bi-substituted LaFeO₃ samples, indicating the formation of a single-phase perovskite. SEM images revealed the quasi-spherical shape of the particles. The photocatalytic activity of La_1-xBi_xFeO₃ (x=0.0, 0.2, 0.4, and 0.6) was evaluated by the degradation of ortho-Toluidine Blue under visible light irradiation, indicating that La_0.8Bi_0.2FeO₃ exhibited excellent photocatalytic activity. The overall removal rate of o-Toluidine Blue reached 90.09% after visible light irradiation lasting for 60 min. We attribute this heightened photocatalytic activity to the grain size and optical properties of prepared sample. Consequently, the La_0.8Bi_0.2FeO₃ can be considered as a very promising photocatalyst in future industrial application to treat effectively wastewater of dyes.

Influence of Exchange and Correlation Interactions on the Spin Polarized Electronic Structure and Magnetic Properties of Ga0.75Mn0.25P in the B3 Blende Structure

2024-03-04T14:01:37+00:00

This study focuses on investigating the influence of exchange and correlation interactions on the spin polarized electronic structure and magnetic properties of Ga_0.75Mn_0.25P in the B3 Zinc Blende phase. First-principle calculations were performed by systematically varying the Hartree-Fock (HF) exchange (α) value from 0 to 25% using the onsite exact-exchange functional for the treatment of the correlated electrons. The electronic and magnetic properties unveil that Ga_0.75Mn_0.25P manifests a half-metallic ferromagnetic behaviour at deferent values of HF exchange. Moreover, as the fraction (α) parameter increases, the band gap increases, leading to modifications in the spin polarized band structures. Additionally, our investigations indicate that exchange and correlation interactions cause an increase in the lattice parameter and volume of the compound. Furthermore, these interactions result in a decrease in the magnetic moments of P and Ga atoms, while the Mn moments increase. These findings provide valuable insights into the behavior of Ga_0.75Mn_0.25P and offer potential applications in the design of spintronic devices.

DFT Studies on Electronic, Elastic, Thermoelectric and Optical Properties of New Half-Heusler XRhZ (X = V, Nb and Z = Si, Ge) Semiconductors

2024-03-04T14:01:36+00:00

Density functional theory is used to explore the physical properties of the new half-Heusler alloys XRhZ (X =V, Nb and Z = Si, Ge). The exchange-correlation effects were treated by the TB-mBJ potential. The four studied compounds are nonmagnetic semiconductor with an indirect band gap. The formation enthalpy, cohesive energy and phonon band structures demonstrated that these semiconductors are structurally and dynamically stable. It was predicted by the elastic study that the XRhZ compounds (X = V, Nb and Z = Si, Ge) have stable mechanical properties, they possess an anisotropic character and reveal the ductile nature with a B/G ratio >1.75. The optical results show an interesting photocatalytic potential for the NbRhSi and NbRhGe semiconductors; they exhibit a high absorption coefficient in the visible domain, which is around 112.10⁴ cm^-1. For energies greater than 10 eV (UV domain), the refractive index is less than one. The thermoelectric results confirmed that the XRhZ (X=V, Nb and Z=Si, Ge) compounds are very attractive for thermoelectric devices working in large temperature range including ambient temperature.

Effect of Gadolinium Content on Magnetic and Structural Characteristics of NFGO Nano-Particles

2024-03-04T14:01:37+00:00

Sol gel auto-combustion was used to create gadolinium doped nickel ferrite nano-particles, which have chemical composition NiFe_2‑xGd_xO₄ (x = 0.00, 0.010, 0.15, 0.20 & 0.25). The investigation focused on how the composition of Gd⁺³ affected the magnetic properties and structural parameters. Magnetic properties were investigated using VSM technique, structural properties were determined using XRD and SEM techniques. XRD graphs verified the establishment of the spinel ferrite phase. With an increase in Gd composition, the crystallite size and lattice parameter increased from 21.0288 to 27.04125 nm and 8.3325 to 8.3367Å, respectively. It was also evident how the composition of Gd⁺³ affected the estimation of bond-angles and lengths in tetrahedral and octahedral structures. SEM micrographs showed that all of the grains had a small amount of agglomeration and that all of the synthesized compositions were homogenous. The range of 140.5–176.2 nm was found to be the average grain size. Using VSM at 300K, magnetic parameters like coercivity, residual magnetization, and saturation magnetization were computed. Until the composition was 0.20, the saturation magnetization and residual magnetization dropped from 30.28 emu/g to 15.35 emu/g and 5.07 emu/g to 3.65 emu/g, respectively. After that, they increased to 34.40 emu/g and 6.52 emu/g, respectively. Until composition 0.20, coercivity was raised from 154 to 261 Oe; after that, it was lowered to 233 Oe.

Effect of Biosynthesized Silver Nanoparticles on The Optical, Structural, and Morphological Properties of TiO2 Nanocrystals

2024-03-04T14:01:28+00:00

The development of efficient metal doped semiconductors for Photovoltaic applications has gained a lot of research attention. In this present paper, pure and silver nanoparticles (AgNPs)-modified TiO₂ nanocrystals (NCs) with different amount of AgNPs (say 50, 100, 150, 200, and 250 µL) were achieved and the effects of AgNPs on the TiO₂ NCs were explored systematically. The optical, structural and morphological properties were probed using UV-visible spectrophotometer, X-ray diffraction (XRD), and scanning electron microscope (SEM). The results of the optical studies showed a characteristic peak of TiO₂ and the redshifting of the peak position was observed by introducing AgNPs. The synergetic effects from AgNPs and TiO₂ results to diminished band gap. The XRD result confirmed the formation of a tetragonal anatase TiO₂ phase with a decrease in crystallite size with increasing AgNPs content. The SEM images show enhanced nucleation and film growth with presence of shining surface which can be seen to contribute to good photon management by enhancing light scattering. The unadulterated TiO₂ and AgNPs-modified TiO₂ have spherical morphology and uniform size distribution ranging from 20 to 30 nm. This study established the view that surface modification of TiO₂ with AgNPs is a viable approach towards achieving an efficient light photocatalyst.

Preparation of N-Si-P-GaSe Heterojunctions Based on an Amorphous GaSe Layer Without Impurities and Study of Their Electrical Properties

2024-03-04T14:01:39+00:00

The electrical and photoelectric properties of anisotype n-Si−p-GaSe heterojunctions obtained as a result of the deposition of a GaSe thin layer on a cold n-Si single crystal substrate by the thermal evaporation method were studied. It was determined that the height of the potential barrier in thermal annealing structures at T = 200 °C during t = 3 hours occurs due to the decrease in the density of states of local levels located near the Fermi level in the amorphous layer. The mechanism of photosensitivity in an isotype heterostructures was analyzed and it was found that the photosensitivity of the heterojunction increases as a result of a decrease in the surface density of state at the contact boundary of the components, by thermal means. The spectral distribution of the quantum efficiency in the n‑Si – p‑GaSe heterojunction was studied and their perspective was determined.

Influence of Doping Conditions on the Properties of Nickel Atom Clusters

2024-03-04T14:01:39+00:00

It is shown that the dynamics of changes in the state of nickel clusters depends on the temperature of the diffusion maximum and the cooling rate. It was found that with increasing annealing temperature and cooling rate, an increase in density and a decrease in cluster size are observed. In this case, the main attention was paid to the determination of the laws governing the change in the density, size, and structure of clusters from temperature and cooling. The process and dynamics of the interaction of clusters depends on the diffusion coefficient of impurity atoms in the lattice and the level of supersaturation of the solid solution. It has been established that with a change in the annealing temperature from T = 1100℃ to 1250℃, the cluster density increases by almost 1-1.5 orders of magnitude, and their size decreases by a factor of 5–6. It seems to us that to obtain clusters with stable parameters, the optimal cooling rate is 200–300℃.

Effect of Electron Transport Layers, Interface Defect Density and Working Temperature on Perovskite Solar Cells Using SCAPS 1-D Software

2024-03-04T14:01:35+00:00

Perovskite solar cells have garnered significant attention from solar cell researchers due to their potential for achieving high efficiency, primarily attributed to their exceptional Electron Transport layer (ETL). One of the key elements of perovskite solar cells for transporting electrons to generate current is the ETL material. Moreover, there is a promising avenue for enhancing stability and reducing fabrication costs by substituting the transport layer. In this study, TiO₂ and SnO₂ were used as ETL materials in the architecture of perovskite solar cells for a comparative analysis between two devices featuring distinct structures: TiO₂/CH₃NH₃PbI₃/Spiro-OMeTAD and SnO₂/CH₃NH₃PbI₃/Spiro-OMeTAD. To evaluate the performance of each electron transport layer (ETL), the SCAPS 1D tool was employed. The investigation involved varying the thickness of the electron transport layers, interface defect density and working temperature, allowing for a comprehensive assessment of key parameters such as voltage at open circuit (Voc), short circuit current density (Jsc), fill factor (FF), and overall efficiency (PCE%). Remarkably, when employing SnO₂ as the ETL, the achieved efficiency stands at 10.10 %. In contrast, utilizing TiO₂ as the ETL yields a slightly higher efficiency of 12.84%. These findings underline the nuanced influence of transport layer materials on the overall performance of perovskite solar cells.

Synthesis, Characterization and Functionalization of P3HT-CNT Nanocomposite Thin Films with Doped Ag2O

2024-03-04T14:01:34+00:00

This research focuses on the synthesis of carbon nanotube (CNT) and Poly(3-hexylthiophene) (P₃HT) (pristine polymer) with Ag doped (CNT/ P₃HT@Ag) nanocomposite thin films to be utilised in various practical applications. First, four samples of CNT solution and different ratios of the polymer (P₃HT) [0.1, 0.3, 0.5, and 0.7 wt.%] are prepared to form thin layer of P₃HT@CNT nanocomposites by dip-coating method of Ag. To investigate the absorption and conductivity properties for use in various practical applications, structure, morphology, optical, and photoluminescence properties of CNT/P₃HT @Ag nanocomposite are systematically evaluated in this study. In this regard, the UV/Vis/NIR spectrophotometer in the wavelength range of 350 to 700 nm is used to investigate the absorption, transmission spectrum, extinction coefficient (k) and refractive index of the samples prepared at room temperature. The XRD results indicate a slight increase in the crystallite size of the synthesized (CNT/ P₃HT@Ag) nanocomposite compared to CNT/P₃HT nanocomposite, which can be attributed to the better dispersion of the P₃HT and its favorable wrapping around the carbon nanotube structures. FESEM results show that the Ag nanoparticles are acting as a bridge between the CNT and P₃HT, creating a strong bond between the two materials that is strong enough to form thicker tubular structures. An appreciable increase in absorbance intensity (approximately 552 nm) is obtained by adding silver nanoparticles to the CNT/P3HT matrix at 0.5% of P3HT. Additionally, the prepared CNT/P3HT@Ag thin films show greater transmittance – more than 42%, 45%, 49%, and 48% for P3HT concentrations of 1%, 3%, 5%, and 7%, respectively. The preparation of the samples' extinction coefficient (k) and refractive index data show that the inclusion of silver nanoparticles to the CNT/P3HT nanocomposite matrix has a significant improvement over the previous samples (CNT/P3HT composite).

Study of Structural and Electronic Properties of CsMgCl3 Compound

2024-03-04T14:01:35+00:00

In this report, we have investigated the CsMgCl₃ compound with the help of the WIEN2K software package. The structural and electronic properties are performed using the full potential augmented plane wave (FP-LAPW) method with the generalised gradient approximation (GGA) approximation as exchange correlation potentials. We used the Birch-Murnaghan equation (BME) to find the structural properties of the material. These include the lattice parameter, the bulk modulus, the first derivative of the bulk modulus, the minimum energy, and the volume. The structural properties match up with the experimental data. Electronic properties in terms of the band structure (BS) and total and partial density of state (T-DOS and P-DOS) profiles of CsMgCl₃ using GGA potentials exhibit an indirect wide energy band gap of 5.35 eV. All these properties show that the CsMgCl₃compound is used as a perovskite in solar cells.

Nitrogen Adsorption on Double-Walled Carbon Nanotube at Different Temperatures: Mechanistic Insights from Molecular Dynamics Simulations

2024-03-04T14:01:33+00:00

Nitrogen-adsorbing carbon nanotubes have received considerable attention in the field of materials science due to their unique properties and potential applications. In particular, nitrogen-adsorbed double-walled carbon nanotubes (DWNTs) can exhibit a wide range of tunable electronic and optoelectronic properties. In this study, the effect of different temperatures (i.e., 300, 600, and 900 K) of DWNT on nitrogen adsorption is investigated through molecular dynamics simulations using the ReaxFF potential. The simulation results show a good nitrogen storage capacity of DWNT, particularly at 600 K, reaching a maximum gravimetric density of 12.4 wt%. This study contributes to a better understanding of the mechanisms governing nitrogen adsorption onto DWNTs at different temperatures.

Properties of Single Crystal Silicon Doped with Vanadium

2024-03-04T14:01:33+00:00

The paper reports the sharp increase in resistivity and the conductivity change (type) in the single-crystal silicon sample doped with vanadium. The electrical and optical properties of single-crystalline silicon were determined Hall- and four-probe measurements and infrared (IR-) spectroscopy. Relative resistance, charge carrier concentration, mobility, and concentration of optically active oxygen and carbon in the samples were determined layer-by-layer. It is shown that in silicon samples doped with vanadium the concentration of optically active oxygen atoms tends to reduce.

Growing Sb2Se3 Films Enriched with Selenium Using Chemical Molecular Beam Deposition

2024-04-10T11:49:50+00:00

This study explores the growth of Sb₂Se₃ films on soda-lime glass (SLG) surfaces using the chemical molecular beam deposition (CMPD) method at a substrate temperature of 500°C. High-purity binary compounds, Sb₂Se₃ and Se, were employed as source materials for film deposition. Scanning electron microscopy (SEM) was employed to investigate the morphological characteristics of the Sb₂Se₃ films. Furthermore, the influence of temperature on the grain size and crystallographic orientation in selenium films was examined. Samples were obtained from a selenium source at temperatures of 370°C and 430°C. The results indicate that increasing the temperature of the selenium source results in the formation of larger grains and the presence of rod-shaped grains of Sb₂Se₃ aligned parallel to the substrate. A sample obtained at 370°C exhibited grains larger than 2 µm in size, evenly distributed across the substrate surface, indicating a uniform growth process. In contrast, when the temperature of the selenium source was raised to 430°C, considerably larger grains measuring approximately 4 μm were detected on the film surface substrate. X-ray diffraction analysis was conducted to gain insights into the crystalline phases and crystal structure of the Sb₂Se₃ films synthesized under different temperatures of the selenium source. The X-ray diffraction patterns displayed prominent peaks corresponding to the crystallographic planes (221) and (211), indicating the presence of strong crystalline phases. Additionally, peaks such as (020), (120), and (310) were observed in the X-ray patterns, further confirming the crystallinity of the films.

Structural Properties of Silicon Doped Rare Earth Elements Ytterbium

2024-03-04T14:01:30+00:00

This paper presents the results of a study of the state of ytterbium atoms in silicon, carried out using the methods of Fourier transform infrared spectroscopy (IR) and Raman spectroscopy (RS). Silicon samples doped with ytterbium impurities were analyzed using FSM-2201 and SENTERRA II Bruker spectrometers. Registration and identification of both crystalline and amorphous phase components in the samples was carried out. The results of the study confirm that doping silicon with ytterbium impurities leads to a decrease in the concentration of optically active oxygen by 30-40%, depending on the concentration of the introduced impurities. It was also found that an increase in the number of defects leads to a broadening of the amorphous zone. It is assumed that similar dependencies exist for the Si-Yb system; however, to the best of our knowledge, similar results have not been reported previously. It is noted that the relative intensity of the three Raman bands in Si-Yb systems in the LTIOS (The light and temperature induced ordered state) state changes, and the relative intensity of Si-Si decreases. This indicates that pendant bonds are mainly formed by the breaking of Si-Si bonds. It was also observed that the light intensity causing this condition is far from that required for laser or solid phase crystallization. Using the Raman spectroscopy method, a structural transformation was discovered, expressed in a densely packed array of nanocrystals with a size of less than 11 lattice parameters. Small clusters were under strong internal stress (up to 3 GPa), which probably prevents the cluster size from increasing beyond the critical value for irreversible crystallization.

Tribological Properties at 20 and 500°C of TiN and CrN Cathodic ARC Coatings Deposited on Ti-6Al-4V Alloy

2024-03-04T14:01:30+00:00

Tribological properties of TiN and CrN coatings deposited by cathodic arc method at three different bias potentials -50, -150 and -300V on Ti-6Al-4V alloy in pair with alumina have been investigated. X-ray diffraction analysis showed that single-phase textured cubic nitrides of TiN and CrN were formed in these coatings. It is shown that the friction coefficient of the coatings is practically equal to that established for the Ti6Al4V alloy, but the wear rate is more than an order of magnitude lower than for the titanium alloy substrate. Coatings deposited at a potential of -50 V show optimal tribological properties at temperatures 20 and 500°C. Friction coefficients for TiN coatings are 0.4-0.8 at 20°C and 0,75 at 500°C; for CrN coatings they are 0.5 at 20°C and 0,7 at 500°C. Wear rates for TiN coatings are 0.86·10^-5 мм³/Нм at 20°C and 3.56·10^-5 мм³/Нм at 500°C; for CrN coatings they are 1.43·10^-5 мм³/Нм at 20°C and 7.13·10^-5 мм³/Нм at 500°C.

Study of the Charge Carrier Collection Coefficient of Silicon p-i-n Photodiodes

2024-03-04T14:01:28+00:00

The paper investigates the collection coefficient of minority charge carriers in silicon p-i-n photodiodes and the influence of certain technological factors on it. It has been found that the diffusion length of minority charge carriers and the resistivity of the material have a significant effect on the value of the collection coefficient, since the collection area of photogenerated charge carriers increases with increasing these parameters. It was also found that an effective method to increase the collection coefficient of photodiodes is to ensure that the thickness of the high-resistance region of the photodiode is equal to the sum of the diffusion length of minority charge carriers and the width of the space charge region. The effect of the concentration of dopants on the responsivity and collection coefficient is investigated. It was found that, in contrast to the calculated data, in which the collection coefficient increases with decreasing concentrations of phosphorus and boron, in the experimental data, with decreasing concentrations of impurities, the responsivity and, accordingly, the collection coefficient decrease due to a decrease in the degree of heterogenization and, as a result, a decrease in the width of the space charge region and the diffusion length of minority charge carriers.

Single and Multiphoton Optical Transitions in Atomically Thin Layers of Transition Metal Dichalcogenides

2024-03-04T14:01:32+00:00

The article discusses the production and properties of two-dimensional atomic layers of transition metal dichalcogenides (TMDs), focusing on the optical properties of monolayers. It begins with an introduction to the discovery of graphene production methods and the subsequent interest in TMDs. The basic properties of TMD monolayers, their crystal structure, and Brillouin zone are detailed. The article explores the energy spectrum of electrons in different valleys and the effective Hamiltonian describing states in parallel spin bands. The discussion extends to the matrix elements of interband optical transitions, including single-, two-, and three-photon transitions. Equations are provided to calculate probabilities of optical transitions, incorporating factors such as polarization vector, frequency of light, and temperature of the sample. Theoretical analysis of constituent matrix elements for these transitions is outlined, emphasizing quantum mechanical aspects. The article contributes researching of the optical behavior of transition metal dichalcogenides (TMDs) monolayers, particularly in structures with complex compositions.

Thermographic Method of Activated Carbon Packing Quality Diagnostics in NPP Air Filters

2024-03-04T14:01:38+00:00

The work is devoted to the tasks of safe operation of nuclear power plants, namely the prevention of inert radioactive gases, iodine, and its compounds from entering the air. The latter is particularly dangerous because it can accumulate in the human body. One of the methods of air purification is the use of air filters filled with activated carbon granules that have undergone preliminary treatment of thermal expansion and impregnation. At the same time, there is a problem with evaluating the change in local aerodynamic resistance as a result of the shape change of granules and their compaction when activated carbon is filled into the filter. For this purpose, the model that calculates the spatial field of movement of ventilation gases through a chamber that simulates an adsorber of the AU-1500 type filled with carbon granules was created. To verify the model, it was necessary to develop approaches to the assessment of the topology of the intergranular space and to draw up ideas about the possible inhomogeneities of such topology due to inhomogeneities in the compaction of granules during backfilling and vibration effects during operation. Therefore, an experimental model based on the assumption that air passage channels are spatially contiguous with electric current passage channels if a potential difference is applied to the "input-output" sections was proposed. Clusters of areas with heterogeneous packing by measuring the temperature distribution, which is released in the form of Joule heat were identified. Correlations between the characteristics of the spread of temperature fields and modes of current trans-mission have been established. It is shown that the obtained experimental data correlate with theoretical calculations of the flow of ventilation gases. The created set of methods allows optimization of the aerodynamic characteristics of the filter to improve their functional properties.

Identification of Heavy Metals Pollution Sources in The Territory Adjacent to NSC “Kharkiv Institute of Physics & Technology” by PMF Method

2024-03-05T22:50:44+00:00

In this paper the content of heavy metals at the territory of Pyatihatki settlement, where the National Scientific Center Kharkiv Institute of Physics & Technology (NSC KIPT) is located. The nuclear-physical methods were used to determine the content of chemical elements in the soil samples taken in 30 points at the territory of Pyatihatki settlement in 2011-2021. The elemental analysis was carried out on the analytical nuclear-physical complex "Sokol". The methods, based on registration of characteristic X-ray radiation of atoms and g-radiation of nuclei excited by accelerated protons, were used. After the measurements completion, the data arrays on the content of 15 chemical elements (N, Na, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, Zr, Br, Sr, Pb) in the soil samples were obtained. The data arrays processing was carried out using the EPA (Environmental Protection Agency) PMF v3.0.2.2.2 software based on the application of the PMF (Positive matrix factorisation) algorithm. ArcView 3.2a was chosen as the basic software product for the analysis of spatial distribution of the major polluting chemical elements. As a result of the performed work, the pollution sources, which have an impact on the territory near the NSC KIPT, have been identified. The source of the soil pollution is the autostrades, among which the road around the city Kharkiv stands out, where an increase in the content of Pb, Sr, Zr, Cr and Cu was detected. A source of chromium contamination, located presumably to the north-east of Pyatihatki settlement, was identified. The analyses of the obtained data showed that the PMF method allows to identify the factors that affect the soil contamination, and to determine the presumptive sources of pollution with the help of wind rose.

The Influence of a Magnetic Field on the Sorption of Radionuclides by Clinoptilolite and Composite Sorbents Based on Zeolites

2024-03-04T14:01:37+00:00

Two methods of using permanent NdFeB magnets and their impact on the sorption of radionuclides (Cs, Sr, Co) by clinoptilolite and composite sorbents based on zeolites are discussed. Sorption processes were considered under dynamic conditions with liquid circulation. No changes in sorption processes were observed when magnetic treatment was applied to solutions containing radionuclide ions. The natural zeolite clinoptilolite and synthetic zeolites NaX and NaA were considered at this stage. In the work, clinoptilolite from the Sokirnitske deposit in the Zakarpattia region of Ukraine was used. Ukraine possesses significant deposits of clinoptilolite. When magnets were applied to the sorbent during the sorption process, an increase in cobalt sorption of 10% was observed for clinoptilolite, and strontium sorption increased by 17%. The influence of a magnet on clinoptilolite is due to the presence of iron ions in the composition of clinoptilolite. The iron content ranges from 0.9% to 2.5%. The composition of the composite sorbent included clinoptilolite and synthetic zeolite NaX. No increase in radionuclide sorption was observed for composite sorbents, likely due to the presence of clinoptilolite in the sorbent composition and the corresponding iron content. The analytical part of the study was carried out using the PIXE (Particle Induced X-ray Emission) method on the analytical nuclear-physics complex "Sokil." The energy range of the accelerator was 200-2000 keV. The complex made it possible to carry out all the main methods of analysis using ion beams. The targets were placed in the exit, at the Chamber for PIXE. To excite the atoms of cesium, strontium, and cobalt a proton beam with an energy of Ер≈1400 keV was used.

Investigation of Temperature and Channel Dimension Effects on CMOS Circuit Performance

2024-03-04T14:01:38+00:00

This paper presents the impact of temperature variations and alterations in transistor channel dimensions on CMOS (Complementary Metal-Oxide-Semiconductor) circuit technology. To facilitate this investigation, we first identified critical parameters characterizing the device's performance, which could exhibit susceptibility to these influences. The analysis encompassed critical metrics such as the transfer characteristic, drain current, logic levels, inflection points, and truncation points. These parameters enabled us to validate the results obtained from the PSPICE simulator, which demonstrated unequivocal effectiveness. Notably, our simulation results unveiled significant effects resulting from a wide temperature range spanning from -100°C to 270°C, offering valuable in-sights into thermal-induced failures. Additionally, the influence of channel dimension changes on factors like drain current and transfer characteristics, as well as temporal parameters including signal propagation delay and rise and fall times, were meticulously examined and appreciated.

Developments of Nanoporous AAO Based Capacitive-Type Sensors for Heavy Metal Ion (Arsenic) Sensing Application

2024-03-04T14:01:32+00:00

In this work the evolution of a capacitive type sensor based on nanoporous anodic aluminum oxide (AAO) fabricated by a two-step anodization process using a low-cost customized setup designed in-house is reported. The parallel plate capacitors were fabricated using aluminum (Al) as base electrode and gold as top electrode, where the porous AAO was used as the dielectric material. This demonstrated the clear dependence of the capacitance values of the as prepared different sensors on the dielectric material’s thickness. The as developed sensors were tested for the detection of arsenic (As) ions.An increase in the capacitance was observed while increasing the concentration of the As ion in aqueous solutions. The presence of As ion was confirmed through EDS (Energy dispersive X-ray spectroscopy) mapping carried out in a FESEM. This change in capacitance can be attributed to the change in dielectric constant of the active material with the incorporation of metal ions.

Vibrational Hamiltonian of Carbonyl Sulphide and Hydrogen Cyanide

2024-03-04T14:01:32+00:00

This study thoroughly investigates the vibrational frequencies of carbonyl sulphide (¹²C¹⁶O³²S) and hydrogen cyanide (HCN) up to the fifth harmonic level. It offers comprehensive insights into vibrational modes by using the Hamiltonian operator formalism and concentrating on invariant operators and algebraic parameters with a one-dimensional Lie algebraic method. The findings are significant for atmospheric chemistry, spectroscopy, and quantum chemistry, contributing to a deeper understanding of molecular dynamics. This research sets the groundwork for future studies in comparable compounds and applications.

Isothermal Decay Analysis of Thermoluminescence Peaks of Quartz for Kinetic Parameter Determination

2024-03-04T14:01:28+00:00

This study delves into the intricacies of isothermal decay analysis applied to thermoluminescence (TL) peaks, focusing on determining kinetic parameters. The study challenges the conformity of the trap responsible for the ITL signals to first, second, or general-order kinetics, supported by the non-conforming decay pattern and the inference of two overlapping first-order TL peaks. This work enhances the understanding of TL peaks and establishes a reliable methodology for characterizing luminescence mechanisms in materials, contributing to advancements in luminescence dosimetry research. These observations lead to the conclusion that the TL data originates from more than one trap, and based on existing literature, it is inferred that there are two overlapping first-order TL peaks. The investigation involves the consideration of isothermal decay data at distinct temperatures (T = 250, 260, 270, 280, and 290°C) and explores challenges associated with achieving precise linear fits for different kinetic order values (b). The nature of decay is interpreted based on the monomolecular theory, suggesting adherence to a first-order process. ITL curves were deconvoluted into two exponential decay curves. The slopes of the regression lines provide activation energy (E) values for curve1 and curve2, respectively: E₁ = 0.99±0.16 eV and E₂ = 1.32±0.18 eV. The frequency factor (s) is determined from the intercept of the regression line: s₁ = 1.32×10⁸ s⁻¹ and s₂ = 1.77×10¹² s⁻¹.

Comparative EPR Analysis of Modern and Fossil Tooth Enamel: Unveiling Aging-Induced Components

2024-03-04T14:01:34+00:00

This study involves comparing EPR signals from three-year-old modern cow tooth enamel with the spectra of fossil tooth enamel exposed to natural background radiation over an extended period. The EPR spectrum of the significantly aged fossil tooth enamel displays additional components absent in the EPR spectra of the modern tooth enamel. Specifically, the septet signal associated with isopropyl (or alanine) radicals is not observed in the EPR signals of modern tooth enamel when irradiated up to 1.3 kGy. It is hypothesized that the isopropyl radicals present in fossil tooth enamel are not a result of radiation but rather stem from the natural breakdown of organic components due to the aging process. This characteristic is proposed as a dependable tool for authenticating tooth samples.

Interaction of Very Thin Double-Layer Fibres with Electromagnetic Radiation. 1. Numerical Simulation

2024-03-04T14:01:27+00:00

Very thin conductive fibers, whose diameter is much smaller than the wavelength, strongly absorb and scatter electromagnetic radiation. The efficiency factors of absorption, scattering and radiation pressure of metal fibers with a diameter of several micrometers in the centimeter wavelength range reach several thousand. The absorption of electromagnetic radiation in two-layer fibers has been studied. In fibers with a metal core and a lossless dielectric cladding, the absorption is the same as in solid metal fibers. In lossy cladding fibers, strong absorption occurs when the fiber diameter is several nanometers. Fibers with a dielectric core and a metal cladding strongly absorb radiation when the thickness of the cladding is comparable to the thickness of the skin layer.

Temperature Dependence of Dielectric Relaxation of Absorption Spectra in the Chlorobenzene Iodobenzene System

2024-03-04T14:01:35+00:00

The article presents the results of a study of the temperature dependence of the dielectric constant ε' and the dielectric loss index ε" of the chlorobenzene-iodobenzene system at wavelengths λ = 6.32; 4.01; 3.21; 2.14; 1.18 and 0.75 V temperature range ‑40℃÷+30℃. The static dielectric constant was determined at a frequency of 7 MHz. The temperature dependence of the time of dielectric relaxation of molecules in the liquid state was determined. It was established that in the specified temperature‑frequency range the dispersion region consists of two parts. Analysis of the temperature dependence of dielectric polarization relaxation in the system chlorobenzene-iodobenzene shows that the relaxation times of the components do not depend on their short-range order. It was also discovered that the rate graph showing the dependence of the logarithm of the relaxation time on the reciprocal of the temperature logτ ~ 1/T, consists of two parts and the value of the static dielectric permeability ε_∞ is non-additive. To explain these results, it is assumed that clusters are formed in this system, the same as in the pure components.

Mechanism of Hydrogen Production in The Processes of Radiation Heterogeneous Splitting of Water with the Presence of Nano-Metal and Nano-MeO

2024-03-04T14:01:34+00:00

In the study, the optimal values of the ratio of the distance between particles to the particle size in the radiation-heterogeneous radiolysis of water in nano-Me and nano-MeO systems were determined. In those systems, the effect of water density and system temperature on the radiation-chemical release of molecular hydrogen obtained from thermal and radiation-thermal decomposition of water was considered. The article also determined the effect of particle sizes and the type of sample taken on the radiation chemical yield of molecular hydrogen. In the presented article, the change of molecular hydrogen according to adsorbed water and catalyst was studied. Thus, in the case of a suspension of nano-zirconium in water, the energy of electrons emitted from the metal is completely transferred to water molecules, which leads to an increase in the yield of hydrogen. When radiolysis of water in the presence of nano-metals, energy transfer can be carried out mainly with the participation of emitted electrons. Therefore, in the case of radiolysis of water in suspension with n-Zr, the yield of hydrogen increases by 5.4 times compared to the processes of radiolysis in an adsorbed state. However, in radiation-heterogeneous processes of obtaining hydrogen from water in contact with metal systems, it is necessary to take into account that as a result of these processes surface oxidation occurs and after a certain time the systems are converted to n-Me-MeO+H₂O_liq.systems. For nano sized oxide compounds, the mean free path of secondary electrons formed as a result of primary processes of interaction of quanta with atoms is commensurate with the particle sizes of nano-oxides (λ ≈ R_(H-оxides)). Further, these electrons interact with the electronic subsystem of silicon. For nanocatalysts, the length of free paths of secondary and subsequent generations of electrons is greater than the size of catalyst particles (R_cat≤100nm). Usually, their energy is sufficient to conduct independent radiolytic processes in the contact medium of the catalyst.

Spectra of Ultrasound Doppler Response Using Plane-Wave Compounding Technique

2024-03-04T14:01:28+00:00

Within the framework of a simple model of the sensitivity function, the Doppler spectra are considered for different ways of generating response signals using plane wave compounding. A Doppler spectrum is obtained for coherent compounding of signals received at different steering angles of waves during their period of changing. Compared to traditional diagnostic systems, the Doppler spectrum width is increased only by limiting the duration of the signals. There is no additional increase in the spectrum width if the compound signals are formed by adding with cyclic permutation, in which signals from each new wave angle are compounded. When a Doppler signal is formed directly from Doppler signals at different steering angles, the spectral width increases both in comparison with the traditional method of sensing with stationary focused ultrasound fields and with the case of coherent signal compouding. The obtained increase in the spectral width has an intrinsic physical meaning. The increase in width is connected with a dynamic change in the Doppler angle, which increases the interval of apparent projections of the velocities of motion of inhomogeneities along the direction of transmitting of a plane wave without inclination.

Modeling the Temperature Dependence of Shubnikov-De Haas Oscillations in Light-Induced Nanostructured Semiconductors

2024-03-05T22:52:14+00:00

In this work, the influence of light on the temperature dependence of transverse magnetoresistance oscillations is studied. A generalized mathematical expression that calculates the temperature and light dependence of the quasi-Fermi levels of small-scale p-type semiconductor structures in a quantizing magnetic field is derived. New analytical expressions have been found to represent the temperature dependence of transverse differential magnetoresistance oscillations in dark and light situations, taking into account the effect of light on the oscillations of the Fermi energy of small-scale semiconductor structures. A mathematical model has been developed that determines the light dependence of the second-order derivative of the transverse magnetoresistance oscillations of p‑type semiconductors with quantum wells by magnetic field induction. A new theory is proposed, which explains the reasons for the significant shift of the differential magnetoresistance oscillations along the vertical axis measured in the experiment for dark and light conditions.

Phase Formation Process in CdSe Thin Films

2024-03-04T14:01:29+00:00

In this work, thin films of cadmium selenide of difrent thicknesses were obtained by chemical deposition and the processes of phase formation in them were studied. Thin layers with a thickness of d = 150 – 500 nm were obtained. Structural studies were carried out using X-ray diffraction. The spectra obtained at room temperature were analyzed. The presence of structural features of the CdSe compound in thin layers has been established. After a thickness d = 400 nm, the process of phase formation begins. The observed atomic planes and Miller indices during the phase formation process are determined.

Molecular Dynamics Study of The Lysozyme-Based Drug Delivery Nanosystems Loaded with Antiviral Drugs and Cyanine Dyes

2024-03-04T14:01:27+00:00

Protein-based drug nanocarriers are increasingly recognized as promising candidates for effective drug delivery, owing to a multitude of beneficial advantages over synthetic materials including low cytotoxicity, biocompatibility, biodegradability, abundance, renewability, and high drug loading capacity mediated by diverse functional groups and interactions. In the present study the molecular dynamics simulation was employed to explore the stability of lysozyme-based drug delivery nanosystems functionalized by the antiviral drugs (favipiravir, molnupiravir, nirmatrelvir and ritonavir) and cyanine dyes (AK7-5, AK5-6, AK3-11). A series of 5 ns or 100 ns MD simulations for the top-scored docked drug-dye-protein complexes, obtained using the PatchDock server was performed at 310 K with GROMACS software using the CHARMM General Force Field. The MD results have been analyzed in terms of the parameters, such as the backbone root mean-square deviation, gyration radius, solvent accessible surface area, the root means square fluctuations. The analysis of calculated parameters for the studied systems enabled us to improve the previously acquired molecular docking data. Taken together, the results obtained indicate that Lz-F-AK3-11, Lz-R-AK75, Lz-R-AK56, Lz-N-AK75, Lz-N-AK3-11, and Lz-M-AK75 systems exhibit the highest stability among the examined dye-drug-protein systems and represent potential candidates for the targeted delivery of the explored antiviral agents.

Characteristics of Nonlinear Dust Acoustic Waves (DAWs) Propagating in an Inhomogeneous Collisionless Magnetized Dusty Plasma

2024-03-05T22:50:15+00:00

In this paper, we have presented our investigation on the characteristics of nonlinear dust acoustic waves (DAWs) propagating in an inhomogeneous collisionless magnetized dusty plasma (MDP). In this problem, we have considered a collisionless plasma consisting of nonthermal ions, non-extensive electrons and negatively charged dust grains. Using the reductive perturbation theory (RPT) we have derived the modified Zakharov-Kuznetsov (m-ZK) equation. The solution of m-ZK equation indicates the nonlinear characteristics of the DASWs in plasma. Our investigation also predicts how the amplitudes of nonlinear DASWs are significantly modified due to the influence of magnetic field, non-extensive electrons and inhomogeneity parameters in plasma. The results obtained in this investigation may be useful for understanding the propagation characteristics and modification of structures of nonlinear waves in both laboratory and astrophysical plasmas.