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Discrete PT-symmetric lattices: spectral properties and stability of solitons
In this work, the spectral properties of discrete PT-symmetric lattices and ring-shaped lattices, as well as the linear stability of PT-symmetric solitons in the nonlinear regime, are analyzed. In this case, the PT-symmetric potential is given in the form of a Gaussian potential, whose real part is equal to zero and whose imaginary part takes positive and negative values at each point. The results show that a phase transition occurs in the system at the PT-symmetry breaking point, which is characterized by the transition of the energy spectrum from real to complex values. It was shown that in the nonlinear regime, solitons are linearly stable in the unbroken PT-symmetric phase and linearly unstable in the broken PT-symmetric phase.
Copyright (c) 2026 https://creativecommons.org/licenses/by/4.0
Mechanisms of perylene pre-nucleation on Ni(111) and SiO2(0001) surfaces
Organic semiconductor thin films are crucial for next-generation electronics, yet their early-stage nucleation on inorganic substrates is poorly understood. We employ reactive molecular dynamics simulations to study the pre-nucleation (clustering) of perylene on Ni(111) and SiO2(0001). Strong chemisorption on Ni(111) stabilizes a flat-lying wetting layer (Stranski–Krastanov mode), whereas weak adhesion and strong π–π cohesion on SiO2(0001) directly yield vertically oriented 3D islands (Volmer–Weber mode). Thermodynamic analysis of cohesive energy and molar Gibbs free energy quantitatively supports these transitions, providing a predictive framework for designing stable organic–inorganic interfaces.
Unraveling the structural and electronic reorganization of oxidized cellulose: a density functional theory perspective on carboxyl-induced modifications
Controlled oxidation of cellulose introduces carboxyl functionalities at the C6 position, significantly modifying its hydrogen-bonding network, crystalline structure, and electronic properties. In this work, density functional theory (DFT) is employed to investigate pristine cellulose Iβ and an oxidized model where the C6 hydroxymethyl group (–CH₂OH) is converted into a carboxyl group (–COOH), mimicking dichromate-induced oxidation. Structural optimization reveals anisotropic lattice distortion, including contraction along the a-axis, slight expansion along the b-axis, and increased lattice angles, indicating rearrangement of interchain packing. Hydrogen-bond analysis shows that oxidation increases the total number of hydrogen bonds from 18 to 24 while shortening the shortest H•••O distance from 1.78 Å to 1.70 Å, reflecting stronger intermolecular interactions. Bader charge analysis indicates significant electron depletion at the oxidized C6 sites, consistent with the electron-withdrawing nature of carboxyl groups. Electronic structure calculations reveal a reduction in the band gap and a downward shift of the chemical potential, suggesting enhanced electron-accepting behavior. Optical absorption spectra demonstrate increased intensity and pronounced anisotropy in the oxidized system. These findings provide atomistic insight into oxidation-induced transformations and establish a theoretical basis for designing functionalized cellulose materials with tailored properties.
Molecular masses and rheological properties of chitosan and sodium carboxymethylcellulose polymers
This study investigates the molecular characteristics of Na-SMC (sodium carboxymethyl cellulose) and chitosan (ChS), as well as the rheological properties of their polyelectrolyte solutions and mixtures. The molecular characteristics were determined using an Ubbelohde viscometer, while the rheological behavior of the gels under shear conditions was examined using a Reotest-2 rheometer. These studies are primarily related to the fields of materials science, polymer chemistry, and rheology, and are aimed at an in-depth investigation of the physical and chemical properties of these polymer systems.
Classical and modern interpretation of nanofluid stability
In this work, the relationships between DLVO theory and dynamic light scattering (DLS) were investigated for a Fe-Cr-Ni-Mn-Si-Mo-Cu nanofluid system obtained through electro-erosive dispersion under the influence of 30 kHz electrical pulses. The increase in hydrodynamic diameter up to 8 $\mu$m in DLS measurements proves that attractive forces (VA) outweigh repulsive forces ($V_R$), while the autocorrelation function demonstrates a sharp deceleration of Brownian motion and a total loss of stability. Although the low charge magnitude ($\zeta$ < 15 mV) and high ion concentration indicate a reduction in the Debye length, there is a possibility of restoring the nano-scale characteristics of these agglomerates through ultrasonic treatment.
Improving the morphology and structure of perovskite solar cells using different hole-carrying layers
In this work, the morphological and structural properties of PEDOT:PSS and PTAA materials as hole-transporting layers (HTLs) were analyzed. Optical measurements showed that the PTAA film has high transmittance in the visible light region. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy(SEM) images confirmed that the perovskite grain size and density in the perovskite composition of the PTAA-based perovskite solar cells (PSCs) were larger. The PSCs using PTAA had better charge separation and higher energy storage. Therefore, this material is better than PEDOT:PSS and is considered a promising option for PSCs in the future.
Copyright (c) 2026 Boburbek G.Khidirov, Sanobar R.Reymbayeva , Lobar R.Nurumbetova, Muhibjon Kh. Imomov https://creativecommons.org/licenses/by/4.0
Electronic and Transport Properties of Ag3PO4 as a basis for catalytic applications
The electronic, structural and transport properties of the semiconductor silver phosphate Ag3PO4 have been investigated using first-principles methods. The influence of deformation on the band gap width, effective masses of charge carriers, their lifetimes and mobilities, elastic modulus constants, and deformation potentials has been studied. It has been shown that silver phosphate with a cubic crystal lattice is a semiconductor with both direct and indirect transitions (energy gaps of 2.54 eV and 2.47 eV respectively), that is consistent with experimental data. It has been established that the effective masses of electrons are approximately three times smaller than those of holes, and the electron lifetime (21.8 fs) significantly exceeds the hole one (2.9 fs), indicating the electronic conductivity of Ag3PO4. With increasing deformation, the effective mass of electrons rises, while the effective mass of holes remains practically unchanged under compressive deformation, decreases under tensile deformation, and then returns to the initial value with further increase in tension. Electron mobility is maximum in the absence of deformation (66.14 cm2/(V · s)) and significantly decreases when deformation is applied. The obtained results can be used in the design of photocatalytic and strain-sensing materials containing silver phosphate.
Excitation of isomeric 4+ states in the photonuclear (γ,n) reaction on the 113In nucleus
This paper presents the results of a study of the excitation of 4+ isomeric states in a (γ, n) photoneutron reaction on the 113In nucleus, as well as an analysis of the energy and probability characteristics of the formation of these states. Using the induced activity method, the energy dependences of the isomeric yield ratio and the reaction cross section for the (γ, n) reaction on the 113In nucleus were determined in the energy range of 1435 MeV with a step of 1 MeV. The obtained experimental data are compared with theoretical calculations. Theoretical calculations of the nuclear reaction cross sections and isomeric cross section ratios were performed using the TALYS-1.6 software package. The calculations were performed over a wide range of incident particle energies, taking into account various nuclear reaction mechanisms, including direct, presumably equilibrium, and pre-equilibrium processes. Standard models implemented in the TALYS code were used to describe the nuclear structure and level density.
Modeling of ammonia dosing processes in the primary circuit of a VVER-1000 reactor using the MATLAB Simulink environment
This paper presents the development and simulation of a control system for ammonia concentration in the primary circuit of a VVER-1000 reactor using Matlab Simulink. The objective of the study is to design a mathematical model of the dosing system, including the pump and control regulator, and to investigate its dynamic behavior under various operating conditions. The research emphasizes the importance of maintaining optimal ammonia concentration to suppress water radiolysis, reduce corrosion rates of structural materials, and ensure the safe and reliable operation of the reactor. A detailed simulation was performed in Simulink, where transfer functions and difference equations describing the object of control were implemented. The study examined system responses to step inputs with different controller gains, analyzing the impact on transient processes and steady- state accuracy. Results demonstrated that the system requires proportional regulation to achieve stable performance. The optimal regulator coefficient was determined. The findings confirm the effectiveness of Matlab Simulink as a modeling environment for control systems in nuclear power applications and lay the groundwork for future integration into real-time environments such as MWBridge.
Theoretical study of the electronic and optical properties of Cu-doped anatase TiO2 using DFT
Using density functional theory (GGA-PBE) as implemented in CASTEP, we present a first-principles study of Cu-doped anatase TiO2. Changes in electronic structure and optical response were investigated using a primitive unit cell model with one Ti atom replaced by Cu (at about 5% of doping). Our calculations show that the corresponding charge-density isosurfaces show strong localization around the dopant site, and that Cu incorporation introduces well-defined impurity states around mid-gap, arising mostly due to Cu-3d orbitals. An examination of the complex dielectric function shows that the transitions involving the Cu-induced mid-gap levels are responsible for the noticeable redshift of the optical absorption edge. By extending its photoresponse into the visible spectrum, Cu doping may significantly improve the photocatalytic performance of anatase TiO2, according to this visible-light activation.
Copyright (c) 2025 https://creativecommons.org/licenses/by/4.0
Modeling of atmospheric phase screens taking into account random wind dynamics
A method for generating nonlinearly changing phase screens of atmospheric turbulence is presented, which is easy to implement and fast in computational load. The method is based on an autoregressive first-order model taking into account the displacement of screens under the influence of a crosswind. In contrast to the classical algorithm described in [1], the proposed approach preserves the correct von Karman spectrum and the physically justified coherence time τ₀ of fluctuations in the refractive index of the atmosphere. In contrast to the classical algorithm described in [1], the proposed approach preserves the correct von Karman spectrum and the physically justified coherence time τ₀ of fluctuations in the refractive index of the atmosphere.
Copyright (c) 2025 А.К. Касимов (Автор) https://creativecommons.org/licenses/by/4.0
The effect of thermal treatment on the optical properties of active layers based on D18:Y6
This study presents the experimental findings aimed at enhancing the performance of polymer solar cells (PSCs). The optical and photovoltaic properties of the D18 donor polymer and the Y6 acceptor were systematically investigated. Detailed analyses were conducted on the absorption spectra, energy level alignment, and intermolecular interactions of the donor and acceptor materials. The experimental results demonstrated that the D18 polymer possesses superior light-harvesting capabilities and photovoltaic performance. When employed as a photoactive layer in combination with the Y6 acceptor, the PSCs achieved a notable power conversion efficiency (PCE) of 15.7%. Furthermore, it was revealed that solvent vapor annealing of the active layer significantly influences the overall device efficiency, suggesting its critical role in optimizing the morphological and electronic properties of PSCs.
Study of the velocities of ejection of jet from the nucleus of comet 67P/Churyumov-Gerasimenko based on the results of observations in Tajikistan
Based on observations of comet 67P/Churyumov-Gerasimenko from October 5 to 8, 2021, conducted at the Sanglokh International Astronomical Observatory of the Institute of Astrophysics, National Academy of Sciences of Tajikistan, an analysis of the obtained digital images was carried out. A detailed analysis using the R filter with an exposure time of 180 seconds revealed gas-dust jets. The distribution of particle ejection velocities was determined using the Whipple method, and the ejection velocity of gas-dust particles was determined using the Jones method. By tracking changes in the positions of the jets, the rotation period of the comet’s nucleus around its axis was determined to be 11 hours, 48 minutes. Based on the constructed isophotes of comet 67P, the activity of the nucleus was established. The isophote analysis revealed an accurate brightness distribution of the comet from the center to the periphery, with the tail clearly visible. The thermal velocities of H2O, CO, O2, and CO2 molecules were determined, and a graph of the temperature dependence on molecular mass was constructed. Based on photometric processing, the size of the comet 67P’s photometric nucleus using the R filter was determined to be 4.51 km, the volume of the nucleus was 22.587 km3, and the overall density of the nucleus was found to be 4.51 g/cm3. The results obtained using the optical telescope are very close to those acquired by the Rosetta spacecraft.
Some Results of Simultaneous Photographic, Television, Spectral, and Radar Observations of Meteors in Tajikistan
The Institute of Astrophysics of the National Academy of Sciences of Tajikistan is one of the first research institutions where, since the late 1960s, various optical observational instruments were introduced at the Hisar Astronomical Observatory (HisAO), including photographic, spectral, and television systems, as well as a radar complex: MIR-2 and MIR-3. From 1977 to 1980, the Institute carried out comprehensive photographic, spectral, television, and radar observations of major annual meteor showers and the sporadic background for the first time. Analysis of the collected data revealed: one simultaneously recorded photo-television meteor, eight photo-radar meteors (meteor No. 770954 having a spectrum obtained via instantaneous exposure), and 57 jointly recorded radio-television meteors. The results of simultaneous radio-optical observations of meteors allowed the authors to obtain for the first time: (a) light and ionization curves for the same meteors; (b) measurements of meteor velocities using two methods: (1) radar; and (2) based on combined radio-television observations; (c) determination of the photometric and ionization masses of meteoroids; and (d) a study of the structure of stream and sporadic meteoroids. Combining the results of simultaneous radio-optical observations of meteors in Tajikistan with similar data obtained in Harvard, Ottawa, and Jodrell Bank made it possible to investigate the dependence of the logarithm of the light-to-ionization intensity ratio on velocity for two groups of meteors by stellar magnitude: (a) bright and (b) faint meteors. The results also made it possible to analyze the dependence of meteor radio magnitude on velocity, which is crucial for the mutual interpretation of optical and radar observational data.
photometric and ionization mass of meteoroids
Investigation of Absorption Effects in the Parametric Amplification of Laser Radiation in MgO:LiTaO₃ Crystal.
In this study, the optical parametric amplification (OPA) process of laser radiation in magnesium oxide-doped lithium tantalate (MgO:LiTaO3) crystal was numerically simulated using MATLAB software. The research focused on identifying the key limiting factors in signal wave amplification within the infrared spectral range, taking into account linear absorption, third-order nonlinearity, and dispersion effects. The results demonstrated that dispersion significantly limits amplification efficiency when the pulse duration is below 10 fs, while absorption becomes the dominant limiting factor when the crystal thickness exceeds 1.2 mm. These findings pave the way for the development of advanced optical amplifiers for telecommunications and ultrashort-pulse laser systems, distinguishing this material from conventional alternatives such as BBO. Background. To derive an analytical expression for the signal wave efficiency considering domain thickness variations and nonlinear effects, and to propose a new approach for optimizing frequency conversion in MgO:LiTaO3. Materials and methods. The reduced nonlinear coupled-wave equations under quasi-phase matching (QPM) conditions were solved using the split-step method, the fourth-order Runge–Kutta algorithm, and fast Fourier transforms (FFT). Results. When the pulse duration is shorter than 10 fs, dispersion reduces the efficiency by 15–20%, while absorption leads to losses of up to 30% when the crystal thickness exceeds 1.2 mm. Conclusion. The derived analytical expression serves as a foundation for optimizing the OPA process in MgO:LiTaO3 and paves the way for the development of novel optical amplifiers that can enhance efficiency by up to 50% in telecommunications and ultrashort-pulse laser systems.
Orbits and Atmospheric Trajectories of 6544 Radiometeors Registered at the Hisar Astronomical Observatory
This work presents the results of radar observations of 6544 radiometeors conducted at the Hisar Astronomical Observatory (HisAO) between December 1969 and February 1970. The coordinates of radiants, velocities, and orbital parameters were analyzed. The observed meteors cover a sky region with ecliptic latitudes ranging from +90° to -23° and have magnitudes brighter than +5m. The measured geocentric parameters include the equatorial coordinates of the radiants and velocities, while the heliocentric parameters are represented by Keplerian orbital elements. The distribution of solar ecliptic longitudes revealed three distinct peaks corresponding to the meteor showers Geminids, Quadrantids, and sporadic meteors. Analysis using the Southworth–Hawkins D-criterion for orbital similarity identified 223 meteoroids belonging to the Geminid stream, with an average geocentric velocity of Vg = 35.1 ± 2.1 km/s. A looser criterion (D = 0.20) increased the number of identified meteoroids to 400, with Vg = 34.6 ± 3.1 km/s. The distribution of geocentric velocities showed a bimodal pattern caused by the influence of heliocentric velocities and Earth’s motion. Analysis of heliocentric orbits revealed 340 meteoroids with hyperbolic orbits, some of which may be attributed to measurement uncertainties. The distribution of geocentric radiants showed concentrations corresponding to major meteor showers. Daily and seasonal variations in meteor counts were analyzed, confirming the presence of a morning maximum in sporadic meteor activity. Analysis of orbital parameters indicated that most meteoroids have large semi-major axes (a > 1.67 AU), characteristic of cometary bodies. The distribution of perihelion distances showed two peaks corresponding to the Geminid and Quadrantid streams. The eccentricity distribution revealed an exponential increase in the number of orbits with increasing e, with a maximum concentration in the range 0.85–1. The inclination distribution was found to be uneven, with a predominance of meteors on low-inclination orbits. The obtained results broaden our understanding of the structure of meteor streams and the distribution of meteoroid orbits in interplanetary space.
Optical properties of 2D Dirac materials (BeN4, IrN4, MgN4, PtN4 and RhN4): a density functional theory study
Using density functional theory calculations, the optical properties of recently discovered 2D Dirac materials BeN4, IrN4, MgN4, PtN4, and RhN4 were examined. The study revealed that the metallic components significantly influence the electronic and optical properties of these materials. For instance, the absorption spectra of the experimentally synthesized material BeN4 can be increased by more than three orders of magnitude in the broad spectral range by substituting Be atoms with other metallic atoms such as Rh. This enhanced absorption is attributed to the substantial contribution of the metal atoms to the density of states of the system. Other optical parameters, such as refractive index and reflectivity, are also modified by the replacement of metal atoms. These findings highlight the possibility of manipulating the optical properties of such low-dimensional materials through metal atom substitutions.
Optical, morphological and photovoltaic properties of CsPbI3 PSCs prepared using two different solutions
The inorganic CsPbI3 active layers used as the active layer in perovskite solar cells (PSC) were investigated by varying the heating temperature and solvents. The optical, morphological, and photovoltaic properties of CsPbI3-based PSCs prepared in DMF and MAAc solvents were studied. The heating temperature of the CsPbI3 active layers was varied from 80 to 120◦C, and the photovoltaic parameters were monitored along with their optical properties. The optimal temperature for heating the CsPbI3 perovskite active layer was determined, leading to the formation of the black phase of CsPbI3. At the optimal heating temperature, the power conversion efficiencies (PCE) of CsPbI3-based PSCs prepared in DMF and MAAc solvents were found to be 8.8% and 9.9%, respectively.
Semi-transparent organic solar cells based on D18 and DEH-X series prepared in different solvents
This study investigates the optical and photovoltaic properties of D18 and DEH-X series donor polymers in semi-transparent organic solar cells (ST-OSCs). Active layers were prepared by mixing D18, DEH-3, DEH-10, DEH-20 donor polymers with L8-Bo acceptor in a 1:1 ratio by dissolving them in toluene and chloroform solvent. Absorption spectra, external quantum efficiency (EQE) and photovoltaic parameters, including short-circuit current (Jsc), open-circuit voltage (Voc), energy conversion efficiency (PCE) and average visible transmittance (AVT), were analyzed. The DEH-X series increases light absorption and improves charge transport, which improves the efficiency of the device.
Copyright (c) 2024 https://creativecommons.org/licenses/by/4.0
The center-of-mass energy of colliding charged particles
In the mathematical characterization of black holes, there are various solutions both within the framework of general relativity and in alternative theories of gravity. These solutions can be theoretically studied by analyzing the behavior of test particles moving around black holes. If a magnetic field exists around a black hole, and if the particles possess electric charge or magnetic properties, such processes become crucial in testing gravity theories and understanding the nature of black holes. This research focuses on the electromagnetic fields and the motion of charged and test particles around axially symmetric black holes located in an external magnetic field. It also studies how the effective potentials of particles change, particularly through the example of the Kerr–Taub–NUT metric. Background. To explore black hole solutions in quasi-Schwarzschild and conformal gravity settings by studying the motion of particles around black holes. Materials and methods. The mathematical framework of macroscopic electrodynamics in general relativity; analytical and numerical methods for solving the equations of motion for particles and fields; analysis of the influence of spacetime parameters on particle motion; examination of how these solutions differ from those in general relativity and their ability to reveal new effects; assessment of the contribution of an external magnetic field to the problem. Results. For the first time, the motion of particles in external magnetic fields around black holes in quasi-Schwarzschild and conformal gravity contexts has been studied. The extent to which these solutions differ from those in general relativity has been analyzed. The influence of the external electromagnetic field on these effects was evaluated for the first time for the considered solutions. The deformation parameter of the quasi-Schwarzschild solution was assessed for both the presence and absence of an external magnetic field, in terms of how well it substitutes the spin parameter in the Kerr solution of general relativity. Conclusion. We demonstrated the degeneracy relations between the magnetic parameter and the ISCO radius values and found that for two different positive values of the deviation parameter, the ISCO radius can be the same for specific magnetic parameter values. The study can be applied to the dynamics of magnetized matter and neutron stars in environments close to SMQT. The investigation of magnetic dipole dynamics showed that the maximum value of the quasi-Schwarzschild field of a black hole in an external magnetic field is effective. The values of the singular angular momentum of magnetic dipoles and the deviation parameter of spacetime around the black hole increase with the magnetic parameter.
Copyright (c) 2024 https://creativecommons.org/licenses/by-nc-sa/4.0
Nanocrystals in silicate glass as potential wells for charge carrier localization
Background. Nanocrystals spontaneously appearing in silicate glass during its melting are considered as potential wells where free charge carriers are localized. For the first time the depth of these potential wells is estimated based on the duration of crystallization of silicate glasses at different temperatures. For silicate glass of different compositions, the depth of such potential wells was found to be equal to 0.26-0.87 eV, while the width of the band gap of the glass itself, determined by the edge of optical absorption, is more than 3 eV. Apparently, the optical width of the band gap of glass is an average value including the depth of potential wells. At the same time these wells are essential for the mechanism of electrical conductivity of thick-film resistors (silicate glasses doped with oxide compounds of ruthenium), creating conditions for variable range hopping (Mott mechanism). Study of the influence of the nanocrystalline structure on the depth of potential wells in the material under investigation, as well as the identification of the relationship between the nanoparticle size and the energetic characteristics of the system. Materials and methods. X-ray diffraction methods were used in the study to determine the phase composition and sizes of the nanocrystals, as well as spectroscopic methods to investigate the energetic characteristics of the potential traps. Numerical calculations based on quantum-mechanical approaches were applied to model the electronic states. The experimental data were processed using statistical methods to ensure the reliability of the obtained results. Results. The study established that a decrease in the size of the nanocrystals leads to an increase in the depth of the potential wells, which is attributed to quantum-size effects. X-ray diffraction analysis confirmed the formation of the nanocrystalline structure, while spectroscopic measurements showed a shift in the energy levels depending on the nanoparticle size. Numerical calculations are in agreement with the experimental data, confirming the influence of the nanocrystals on the electronic properties of the material. Conclusion. The conducted study showed that the nanocrystalline structure significantly affects the depth of potential wells, which is associated with the manifestation of quantum-size effects. Both experimental and theoretical results confirmed that a decrease in the nanoparticle size leads to an increase in the energy gap and changes in the electronic properties of the material. The obtained data could be useful for the development of new nanostructured materials with specific energetic characteristics.
Fabrication of zinc oxide nanostructures via a low-temperature method and investigation of their photoluminescence properties
ZnO nanorods were successfully synthesized by the low-temperature hydrothermal method on a grid formed by cross-weaving stainless-steel wires. Our method includes seeding process by simple dip-coating technique, followed by post annealing process and hydrothermal growth process of ZnO nanostructures. When the nanorods were synthesized a second time, their size increased and the maximum of the photoluminescence spectrum shifted toward the larger wavelength. It was observed that the shift of the PL emission band was associated with the increase in the size of the nanostructures. At the same time, the photoluminescence spectra of the samples showed an increase in the emission band associated with defects. Considering that the defect observed in the PL spectrum is interstitial oxygen, the increase in the emission band corresponding to this defect in the doubly synthesized samples indicates that they are a bulk defect.
Copyright (c) 2024 ​Р. Жалолов, ​Б. Рустамова (Автор) https://creativecommons.org/licenses/by/4.0
Enhancing the efficiency of physics education in military institutions using mobile applications and robotics
This article explores the use of mobile applications and robotics to improve the efficiency of physics education in military institutions. Pedagogical experiments were conducted to assess the impact of these technologies on students learning outcomes. The findings indicate a significant improvement in students understanding and engagement with physics concepts when these tools were integrated into the curriculum. Today, it is important to improve the quality of teaching physics in educational institutions, introduce modern teaching methods into the educational process, select talented students, prepare competitive specialists for the labor market, develop scientific research and innovation, and direct their attention to practical results. The structure, content, methods, and organizational forms of implementing the polytechnic direction of education are undergoing changes in the framework of teaching physics. The use of robotics and mobile applications is a new direction in the theory of polytechnic education. Modeling a new series of laboratory devices using robotics elements based on the content of physical science for cadets of higher military educational institutions, as well as the delivery of educational literature and simulation classes related to physics through mobile applications in pedagogical research “Educational robotics” and is associated with the concept of “educational mobile application”. In this regard, the study of the basics of robotics and mobile applications should become one of the necessary elements of the content of modern polytechnic education.
robotics in teaching and physical practice
Copyright (c) 2024 Д. Насриддинов, Д. Бегматова (Автор) https://creativecommons.org/licenses/by/4.0
Role of metal atom doping on the transport properties of zigzag graphene nanoribbon with a vacancy defect
Graphene nanoribbons (GNRs) with structural defects have attracted significant interest due to their tunable electronic and magnetic properties. In this study, we investigate the role of transition metal (Co and Fe) doping on the transport properties of zigzag GNRs containing single vacancy defects, terminated either by unsaturated carbon atoms or pyridinic nitrogen atoms. Using density functional theory (DFT) combined with non-equilibrium Green’s function formalism, we analyze the electronic transport characteristics and spin-dependent effects. Our findings reveal that metal atom doping has a contrasting impact depending on the defect type: in carbon-terminated vacancies, metal atoms reduce conductivity due to enhanced localization of electronic states, while in pyridinic defects, they enhance conductivity by extending transmission states. Additionally, metal doping significantly improves spin filtering efficiency, making doped GNRs promising for spintronic applications. These results emphasize the importance of defect engineering in graphene-based nanodevices and provide insights into optimizing electronic transport properties through selective doping strategies.
Copyright (c) 2024 Гафур Эшонкулов, Анора Мейлиева, Голибжон Бердияров (Автор) https://creativecommons.org/licenses/by/4.0
The dynamics of charged particles and magnetic dipoles around magnetized quasi-Schwarzschild black holes.
Annotation: Since the theory of general relativity is a classical theory, it is not without problems. One of the main problems is singularity. Singularities occur at the centers of black holes or in cosmological models, resulting in infinite values. For example, in cosmology, at the initial point, there is infinite curvature, infinite density, and infinite temperature. This implies that cosmological singularity is present in the theory of general relativity. From an astrophysical perspective, singularity also exists at the center of black holes. When calculating the Kretschmann scalar, the curvature at the center tends to infinity. However, the presence of infinity indicates problems in physics and shows that the theory of general relativity cannot be applied universally. There are various solutions for describing black holes mathematically within the framework of general relativity and alternative theories of gravity. These solutions can be studied by examining how test particles behave around black holes. If a magnetic field is assumed to exist around a black hole and particles are considered to have electric charge or magnetic properties, studying such processes is essential for testing theories of gravity, particularly for understanding the nature of black holes. This research involves studying the electromagnetic fields around axially symmetric black holes located in external magnetic fields and analyzing the changes in the effective potentials of charged and test particles during their motion, as well as examining this in the context of the Kerr-Taub-NUT metric. Objective: To study the solutions of black holes under quasi-Schwarzschild and conformal gravity conditions by analyzing the motion of particles around black holes. Methodology and methods: The mathematical apparatus of macroscopic electrodynamics within the framework of general relativity; analytical and numerical methods for solving the equations of motion for particles and fields. Studying the impact of space-time parameters involved in the solutions on the motion of particles; evaluating how these solutions differ from those in general relativity and their ability to exhibit effects; assessing the contribution of the presence of an external magnetic field to the problem. Novelty of the results: For the first time, the motion of particles around black holes under quasi-Schwarzschild and conformal gravity conditions with an external magnetic field has been studied, and the degree to which these solutions differ from those in general relativity has been analyzed. The influence of the external electromagnetic field on these effects has been evaluated for the first time for the considered solutions. The deformation parameter of the quasi-Schwarzschild solution has been assessed in terms of how well it substitutes the spin parameter of the Kerr solution in general relativity, both with and without an external magnetic field. Introduction: Despite attempts to detect neutron stars, the gravitational interactions at the center of the Milky Way have led to the presence of an ultra-massive black hole, Sagittarius A*, which is observed as processed radio emissions. One reason for the absence of pulsars around Sgr A* could be the propagation of radio waves in the plasma environment surrounding the black hole, while another could be the effect of the magnetic field between the dipole moment of a neutron star and the magnetic field generated by the magnetic charge or electric current of the central black hole. The stable orbital and chaotic motion of neutral particles, the dynamics of charged particles around static and rotating black holes, and their quasi-harmonic oscillations in asynchronous uniform external magnetic fields and the plasma magnetosphere encompass various black holes. The Lyapunov method, in particular, can be used to demonstrate the difference between regular and chaotic orbits. Moreover, minor system effects and gravitational influences lead to the reduction of chaotic motion.
Copyright (c) 2024 М. Худойбердиева (Автор); Н. Джураева (Переводчик) https://creativecommons.org/licenses/by/4.0
Integrated approach in teaching the subject "EARTH'S MAGNETIC FIELD".
Integration of educational subjects in the educational process is a requirement of the present time. Because the integration of educational subjects is important for the integration of education and upbringing, for the development of students as a person who is patriotic, kind to nature and the environment, and embodies spiritual and moral qualities. In our opinion, in this regard, the training conducted on the basis of interdisciplinary integration classes will have a very good effect. Because the basis of the process of integrating sciences and scientific knowledge is the unity of the material world, i.e. nature, society and the mutual coherence of its determination. In this article, we describe the method of conducting an integrated conference lesson on the topic "Earth’s magnetic field" using integrative sciences: physics-geography-biology. Through this lesson, students can develop ideas about the causes of geomagnetism and the geomagnetic field.
Copyright (c) 2024 Dilfuza A. Begmatova (Author); Bonu A. Yakubova (Translator) https://creativecommons.org/licenses/by/4.0
Raman spectroscopy of the interaction of molecules (atoms) with the surface of a transparent solid
Raman spectroscopy is a powerful method for studying the interaction of atoms and molecules with the surface of solid materials. This method provides information about the structure, chemical activity, and physical properties of the surface at the molecular level. The study examined the spectral properties of xenon atoms on the surface of quartz glass under the influence of monochromatic coherent resonant radiation. The main results of the experimental investigation of the processes involving the interaction of xenon atoms with the surface of a transparent solid using Raman spectroscopy are presented, allowing us to literally observe the atomic structure of xenon under laser radiation. Xenon, being an inert gas, does not exhibit noticeable behavior under normal conditions. However, under the interaction with laser radiation, vibrational states of the xenon atom can occur due to its interaction with pore walls. This interaction with the surface leads to characteristic changes in its spectra. In this case, the frequency shifts of the Stokes and anti-Stokes bands, being less than 100 cm^-1, indicate the relatively weak force of such interaction and corresponding changes in the adsorption potential of the atoms. The significance of this research also lies in the determination of molecular constants, which are absent in the gaseous state of xenon, by using photo-stimulated deepening of the adsorption potential of adsorbed atoms.
polarization interaction with the surface
Copyright (c) 2024 М.А.Захидова (Автор) https://creativecommons.org/licenses/by/4.0
Electrical properties of organic semiconductors based on polyacrylonitrile
Conductivity and static permittivity of heat-treated polyacrylonitrile products with polyconjugation regions are measured in the vicinity of the percolation threshold. It is found that below this threshold, the experimentally obtained dependences of conductivity and static permittivity on the volume content of polyconjugation regions in these materials differ from the dependences calculated within the percolation theory. The origin of this discrepancy is discussed in terms of the spatial-structural hierarchical model proposed by Balberg et al. for composite materials. Analysis of the temperature dependence of conductivity within the local activation energy of conductivity in them shows the formation of a continuous spatial structure of tunnel-connected polyconjugation regions.
Semiconductor heat-treated polyacrylonitrile
Copyright (c) 2024 Д. Саидкулов (Автор); М.Карабаева, Я.М. Рахимова , Ш. Камилов , У.Абдурахманов (Переводчик) https://creativecommons.org/licenses/by/4.0
Excitation of isomeric states in the reactions (γ, n) and (n, 2n) on the 59Co nucleus
The cross sections for the formation of isomeric states in the reactions (γ, n) and (n, 2n) on the 59Co nuclei were measured using the induced activity method. The energy dependencies of the isomeric ratio of the yields of the (γ, n) reactions in the energy range of 1435 MeV with a step of 1 MeV were obtained. The experimental results are compared with the data from other studies and the TALYS-1.6 calculations.
Copyright (c) 2024 С.Р. Палванов (Автор); Т. Ахмаджанов, С. Ашуров, О. Тожибоев (Переводчик) https://creativecommons.org/licenses/by/4.0
Aggregation mechanisms of vacuum NI and NIO nanoparticles
Вывод ограниченность измерительных возможностей экспериментальных приборов затрудняет полное понимание процессов агрегации наночастиц. Особенно актуальным остается изучение механизмов агрегации нанокомпозитов, таких как Ni / NIO, для контроля образования и относительного состава композитов. В этом отношении в этой статье используется моделирование реактивной молекулярной динамики для изучения механизмов агрегации нанокластеров NI и NIO. Результаты показали, что атомы кислорода оказывают значительное влияние на процесс агрегации. В частности, стабильность нанокластера NIO высока за счет атомов кислорода, а атомы кислорода снижают степень связывания атомов никеля в нанокластере NIO с другими атомами нанокластера. В результате, в то время как нанокластеры Ni имеют тенденцию стабилизироваться, образуя взаимную химическую связь из-за агрегации, нанокластеры NIO пытаются войти в агрегацию через слабые силы Ван-дер-Ваальса. В целом, это исследование приобретает все большее значение для будущих исследований, направленных на разработку нанокомпозитов металлов/оксидов металлов с желаемыми свойствами, помогая лучше понять процесс агрегации нанокластеров NI и NIO на атомарном уровне.
Copyright (c) 2024 Ф.М. Сафаров (Автор); Ф.Х. Хайдаров, K.Б. Эгамбердиев, Т.А. Ахмаджанов, У.Б. Халилов (Переводчик) https://creativecommons.org/licenses/by/4.0