BULLETIN OF THE L.N. GUMILYOV EURASIAN NATIONAL UNIVERSITY. PHYSICS. ASTRONOMY SERIES

Fixed point analysis with steep exponential potential

Muskan Khan — 2025-12-25

We investigate the dynamics of the steep exponential cosmological model by recasting it as a
Newtonian-type dynamical system. Our analysis focuses on the autonomous dynamical
system with particular attention to the asymptotic behavior of the cosmological model. We
introduce a set of first-order differential equations governing the evolution of the variables.
We identify the critical points of this system and examine their stability using eigenvalue
analysis. The classification of these points—stable, unstable, or saddle—provides insight into
the qualitative evolution of the universe. The dynamics of the scalar field, characterized by a
potential V(ϕ), are analyzed using dimensionless variables within an autonomous system
framework. We find that the steep exponential potential yields a stable critical point for
certain parameter ranges, representing a late-time attractor. Using phase-space analysis, we
visualize the trajectories and stability properties of the model, offering a comprehensive
picture of scalar-field-driven cosmological evolution.

Slow–roll inflation in the power-law scalar model

Aisara Ratbay — 2025-12-25

In this work, we examine an inflationary model driven by a scalar field that evolves according to a power–law dependence on cosmological time. This assumption allows the Einstein–Klein–Gordon equations to be solved analytically within a flat FLRW metric and makes it possible to obtain closed-form expressions for the key dynamical quantities of the early Universe. Based on the chosen scalar field profile, the Hubble function and the scale factor are computed, enabling a detailed analysis of the emergence of accelerated expansion. The potential of the field and its derivatives are reconstructed directly from the equation of motion, which in turn allows us to derive analytical formulas for the Hubble and potential slow-roll parameters. The time evolution of these parameters is analyzed in order to determine the regime of validity of the slow-roll approximation and to identify the natural endpoint of the inflationary phase. The obtained results demonstrate that a power-law configuration of the scalar field can sustain a prolonged stage of inflation and accurately reproduce the main features of slow-roll dynamics within the framework of General Relativity.

Extending the Covariant Confined Quark Model to Describe Radial Excitations of Heavy Quarkonia

Zhomart Tyulemissov — 2025-12-25

We present an extension of the Covariant Confined Quark Model (CCQM) that enables a consistent description of radial excitations of heavy quarkonia. The conventional CCQM formulation, based on static constituent quark masses, faces a limitation in describing states whose squared mass exceeds the sum of the squared constituent masses. To overcome this, we introduce a running constituent quark mass in the quark loop, allowing an accurate representation of excited hadronic decays. The binding energy of an excited state is assumed equal to that of the corresponding ground state, leading to a simple mass relation between quarkonia and their constituents. Model parameters are determined from experimental data on leptonic decays of charmonia and bottomonia, showing excellent agreement with observations. Furthermore, an orthogonality condition for radial excitations is implemented through modified vertex functions, ensuring that distinct excited states do not mix. This refinement leads to improved internal consistency and predictive power of the CCQM for excited hadronic systems.

the ELECTROSPINNING-ASSISTED FABRICATION OF ZNO NANOSTRUCTURES: OPTIMIZATION OF PARAMETERS FOR TAILORED PARTICLE SIZE

Aizhan Rakhmanova — 2025-12-25

The present study focuses on the synthesis of ZnO nanostructures via an electrospinning-assisted technique, followed by calcination under carefully controlled thermal conditions. The electrospinning process resulted in the formation of continuous, uniform, and bead-free polymeric precursor fibers, with a noticeable reduction in average fiber diameter. This clearly demonstrates the influence of electrospinning parameters, such as applied voltage, solution concentration, and flow rate, on the resulting fiber morphology. Subsequent calcination not only removed the polymeric matrix but also induced the crystallization of ZnO, transforming the fibrous structure into well-defined nanoparticles. The crystallite size of the obtained ZnO was strongly dependent on the calcination temperature, with the smallest crystallites achieved under optimized thermal treatment, thereby offering a route to fine-tune the nanostructure dimensions. Elemental analysis by energy-dispersive X-ray spectroscopy (EDS) confirmed the exclusive presence of zinc and oxygen, verifying the high purity and compositional integrity of the synthesized material. Furthermore, X-ray diffraction (XRD) analysis revealed sharp and intense diffraction peaks corresponding solely to the hexagonal wurtzite phase of ZnO, with no evidence of secondary phases or impurities. These results collectively demonstrate that electrospinning, coupled with controlled calcination, provides a robust, cost-effective, and scalable approach for producing high-quality ZnO nanostructures with desirable structural and compositional features. Such nanostructures hold significant promise for diverse applications, including gas sensing.

STUDY OF SORPTION PROPERTIES AND QUANTUM-CHEMICAL MODELING OF COMPOSITE MATERIALS IN RELATION TO URANIUM (VI) IONS

Balzhan Satanova — 2025-12-25

One of the most pressing issues in the field of environmental safety today is the protection of surface and groundwater from pollution of heavy metals and radionuclides, most of which can be found in industrial wastewater. That is, sorption technologies are widely used to remove pollutants. In most cases, these technologies provide access to scientifically based standards for the maximum permissible amount of pollutants in water. Natural and wastewater treatment technologies make it possible to widely use various layered raw materials, including clay minerals. The advantage of their use is due to the low cost of raw materials with sufficiently high sorption characteristics in relation to inorganic toxicants. So, in some cases, due to the insufficient selectivity of such sorbents, it is necessary to remove traces of pollutants, especially from waters of complex chemical composition, which contain complex-forming components of natural and man-made origin.

Synthetic inorganic silicon-based sorbents are obtained by various methods of surface functionalization of sorbents to increase selectivity. Such methods include the use of organosilicon compounds containing active acid groups (SH, COOH, P(O)(OH)₂), basic groups (primary,secondary and tertiary amino groups, pyridine) and their combinations.

Stochastic interpretation of quantum mechanics

Молдир Алиева — 2025-12-25

The paper addresses the problem of expressing (describing and interpreting) quantum mechanics in terms of probability theory. The solution is demonstrated through computational results based on certain principles, (viewpoints and postulates). In particular, the expectation value of a quantity corresponding to a quantum mechanical operator in the momentum representation is expressed via a complex quasi-probability function. A relation for the quasi-probability function is obtained for the case where the state of the system is described by a density matrix. The numerical representation of the Hamiltonian operator is examined, both in forms that correspond to and deviate from the classical model. Averaged expressions with respect to the quasi-probability function are derived for the stationary case. The problem of describing a stochastic process occurring in complex phase space using a quasi-probability function was addressed by means of a differential equation for the density matrix. It was proven that this equation reduces to the Liouville equation for quantum phenomena in the limit of a vanishing Planck constant, and that the quasi-probability function transforms into an ordinary probability distribution (a specific positive function). Conditions were established under which the equation for the probability density transitions into an approximate complex equation structurally analogous to the Fokker–Planck equation for a diffusive Markov process. Stochastic differential equations corresponding to this complex equation were presented, which define the connections between random processes and the quasi-probability function and incorporate all necessary information for quantum-mechanical calculations. Finally, a system of motion equations in the quasi-classical approximation and stochastic differential equations relevant to the general case and characteristics of the wave function were derived. All computational results and theoretical assertions were thoroughly discussed, and the necessary conclusions were drawn.

Study of the influence of ionic modification of composite ceramics on resistance to high-temperature degradation and thermal shock tests

Artem Kozlovskiy — 2025-12-25

The paper presents the results of studies of the effect of ion modification of near-surface layers of ceramics based on zinc titanate on high-temperature corrosion processes and thermal shock effects simulating critical situations when using this type of ceramics as anode materials for solid oxide fuel cells. The creation of a modified layer in ceramics was carried out by irradiation with O+ ions with different fluences, the variation of which caused different degrees of structural damage created as a result of the interaction of incident ions with the crystalline structure of the near-surface layer with a thickness of about 13 – 13.5 μm. During the thermal stability tests carried out on ceramic samples, involving long-term exposure to high temperatures, it was found that the creation of a modified layer through ion irradiation allows for increased resistance to corrosion and degradation processes, as well as a reduction in the degree of destruction of the strength properties of the near-surface layer of ceramics. It was determined that the optimal conditions for modification are ion irradiation with fluences of 10¹² - 5×10¹² ion/cm², at which the degree of structural changes created in the near-surface layer makes it possible to minimize the negative effect associated with thermally induced corrosion and degradation processes.

Л.Н.Гумилев атындағы ЕҰУ космофизикалық кешен қондырғысының деректері бойынша ғарыштық сәулелер қарқындылының өзгеруін тіркеу және талдау

Ержан Алтаевич Тулеков — 2025-12-25

This paper presents the main technical characteristics of the CARPET installation, which forms part of the Cosmophysical Experimental Complex at L. N. Gumilyov Eurasian National University. It reports the results of experimental studies carried out between 2017 and 2024, along with selected aspects of the analysis of recorded variations in cosmic ray fluxes and parameters of the geomagnetic and interplanetary environment. A comparative analysis of temporal variations in secondary cosmic ray fluxes is provided, employing geomagnetic indices (Kp, Ap, Dst), solar wind plasma velocity (Fs), and data from ground-based neutron monitors during major geomagnetic disturbances in 2017, 2021, and 2024, as registered by CARPET detector modules at the university’s scientific complex. The study also incorporates data on solar flare activity, including graphical representation, and examines the characteristics and parameters of solar flares responsible for geomagnetic disturbances. In addition, information on magnetic storms is presented. The analysis reveals the occurrence of Forbush decreases, with their specific features and properties discussed. The findings demonstrate that variations in cosmic ray intensity are driven by solar surface activity and are linked to subsequent changes in elements of the geomagnetic field

ӘР ТҮРЛІ ПІШІНДЕГІ ТОЗАҢДЫ БӨЛШЕКТЕРДІҢ МЕЗОСФЕРА БИІКТІКТЕРІНДЕ ЗАРЯДТАЛУЫН САЛЫСТЫРУ

Гульнур Шиникулова — 2025-12-25

Abstract. This work considers the charging process of dust particles depending on their shape when interacting with plasma particles of O, O₂, O₃, and OH gases, among the many surrounding gases at mesosphere altitudes. For the purpose of comparison with spherical particles, the dependence of their charge on electron temperature was determined, taking into account the capacitances of cylindrical and disc-shaped particles. Calculations were performed for the ionospheric plasma at an altitude of 85 km, with a temperature of 150 K, electron and ion concentrations of 10¹⁰ м^-3 and an ion frequency of 10⁵ с^-1. The OML theory was used to model the charging of dust particles. The calculation results showed that the shape of the dust particles in the mesospheric plasma affects the magnitude of the charge: spherical particles have the largest negative charge, cylindrical particles have a somewhat smaller charge, and disc-shaped particles have the smallest charge.

Альфа-бөлшектердің көміртегі ядроларында шашырауы кезіндегі зат алмасу процестері

Нұрдәулет Тулешов — 2025-12-25

Abstract

This article provides a comprehensive analysis of the mass–energy exchange processes and nuclear interactions occurring during the scattering of alpha particles by carbon nuclei. The study examines the penetration mechanism of alpha particles into the nucleus, the changes in their energy, and the specific features of elastic and inelastic scattering processes. In particular, the work describes in detail the modifications in the level structure of the carbon nucleus resulting from collisions with alpha particles, the formation of excited states, and the redistribution of energy within the nucleus.

The article discusses the theoretical foundations of Rutherford scattering, the Coulomb barrier, quantum-mechanical tunneling phenomena, and the characteristics of interactions determined by the nature of nuclear forces. The role of experimental methods-such as particle detection detectors, scattering angle measurement techniques, and spectroscopic energy analysis-is also highlighted.

The research findings demonstrate the significance of alpha-particle interactions with carbon nuclei for understanding nuclear structure physics. These processes play a crucial role in clarifying nuclear reaction mechanisms, investigating the properties of light nuclei, and improving applied studies in the fields of nuclear energy, medicine, and materials science.

Keywords: alpha particle, carbon nucleus, scattering, nuclear reaction, elastic and inelastic collision, nuclear excitation levels, nuclear forces, energy transfer.

The role of the formation of buffer V2O5 inclusions in the composition of composite ZrO2 – Al2O3 ceramics on the change in strength characteristics

Seitmaganbet G.B. — 2025-12-25

The paper presents the assessment results of the effect of addition of V₂O₅ dopant to the composition of composite ZrO₂ – Al₂O₃ ceramics and the formation of buffer inclusions on resistance to external mechanical influences and enhancement of resistance to cracking under mechanical loads. During the studies conducted, it was established that the addition of the V₂O₅ dopant to the composition of ceramics with a concentration above 0.1 M leads to the formation of buffer inclusions in the intergranular space formed by ZrO₂ grains and the Al₂O₃ matrix, while the formation of buffer inclusions is due to the low melting point of V₂O₅, resulting in the melting of vanadium oxide during sintering and subsequent vitrification and crystallization during cooling in the intergranular space. During assessment of the strength characteristics, in particular hardness, crack resistance and compressive strength, it was found that at low dopant concentrations, strengthening is caused by structural changes associated with size effects, which are expressed in the growth and coarsening of ZrO₂ grains in the Al₂O₃ matrix. At concentrations above 0.1 M, the growth in resistance to external influences is due to the formation of buffer inclusions, the filling of the intergranular space with which leads to the inhibition of crack formation processes and an increase in resistance to mechanical loads.

Photoluminescence of gallium antimonide (GaSb) crystals doped with selenium (Se) and tellurium (Te)

Maikul Kusherbayeva — 2025-12-25

Abstract. This paper provides a brief overview of main works, dedicated to the study of photoluminescence in gallium antimonide crystals, as well as the features of the band structure and classification of impurity states. Photoluminescence of gallium antimonide doped with selenium and tellurium in the concentration range is presented (. ) for selenium and tellurium respectively. It is shown that GaSb photoluminescence is determined by changes from the conduction band to the second ionized state of the double natural acceptor. The shape and position of the maximum of the emission lines is determined by the Coulomb potential of the impurity, additional minima of the conduction band and resonant impurity states associated with them. It was revealed that the difference in the photoluminescence spectra of gallium antimonide crystals containing different donor impurities (selenium, tellurium) is due to the influence of resonant impurity levels associated with the L-minima of the conduction band. Theoretical calculations of the shape of GaSb photoluminescence spectra were performed. The position of the peak and the short-wavelength wing of the emission lines are essentially determined by the position of the Fermi level, which is due to the sharp increase in barrier transparency with increasing electron energy. The practical significance of the results in this article is also related to the widespread use of optical and photoluminescence phenomena in various types of semiconductor devices.