Open Access
The "Journal of Fundamental and Applied Research" is the only specialized journal in the Republic in the fields of fundamental and applied research and covers all the major areas of research and development across various scientific domains.
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Nozima Juraeva, Malika XudoyberdiyevaIn this article, we study the Hayward black hole surrounded by quintessence. The Hayward metric is a spherically symmetric charged regular black hole, a modification of the Reisnner–Nordström black holes of Einstein equations coupled to nonlinear electrodynamics. The critical mass values and the normalization factor are obtained. We also describe the horizons and the extremal condition of the Hayward black hole surrounded by quintessence. Setting the quintessence state parameter in the particular case of \(\omega_q=-2/3\), we study the effective potential. We discuss its essential geometrical properties such as scalar invariants and the size of innermost stable circular orbits. The dynamics of test particles around the Hayward black hole is also studied.
M.S. Nadirbekov, S.N. Kudiratov
A model with effective triaxiality even-even nuclei with quadrupole and octupole deformations is used to explain energy levels of yrast and first-non-yrast alternating-parity bands. The Davidson potential is used to solve the radial part of the vibration-rotational Schr\"{o}dinger equation in polar coordinates. The yrast and first-non-yrast alternating-parity bands of the even-even nuclei \(^{154}\)Sm, \(^{162}\)Er, \(^{228,230,232}\)Th, \(^{236,238}\)U and \(^{240}\)Pu are described by the proposed model. The peculiarity of simultaneous consideration of quadrupole and octupole deformed even-even nuclei with effective triaxiality is shown. The importance of taking into account collective quadrupole-octupole modes is presented.
Nafisa Yuldasheva, Lola Yusupova
The extraction of natural bitumen using green solvents presents a sustainable alternative to conventional methods that rely on hazardous organic chemicals. This study investigates the optimal conditions for extracting natural bitumen through environmentally friendly solvents such as d-limonene, ethanol, ethyl lactate, and ethanol--water mixtures. Key process parameters---including solvent type, solvent-to-bitumen ratio, temperature, and extraction time---were systematically varied to evaluate their effects on extraction yield. The highest efficiency (78.5\%) was achieved using d-limonene at 70\({}^\circ\)C with a solvent-to-bitumen ratio of 15:1 and an extraction time of 60 minutes. The extracted bitumen was analyzed for physicochemical properties, confirming its suitability for industrial applications. The results highlight the potential of green solvents in promoting cleaner and more sustainable bitumen recovery methods, aligning with global environmental and safety standards. This study contributes to the advancement of eco-friendly technologies in the bitumen and asphalt industries.
Alexander Rogachev, Bobirjon Adizov, Nasiba Bayrayeva, Sayyora Ganieva
This study investigates the temperature--frequency dependencies of the dielectric properties of polymer composite materials (PCMs) based on modified thermoplastics filled with kaolin (AKT-10) particles. Kaolin powders (AKT-10) with effective particle sizes of 2 \(\mu\)m and 20 \(\mu\)m were used as fillers. The structure formation processes of the PCMs were carried out under a magnetic field at elevated temperatures. Temperature--frequency dependencies of the relative dielectric permittivity and the loss tangent were established depending on the filler concentration, particle size distribution, structural organization technologies, and the conditions of magnetic field exposure.
Alexander Rogachev, Bobirjon Adizov, Nasiba Bayrayeva, Alisher Auyesbayev, Sayyora Ganieva
This article explores key methods for enhancing the strength of components manufactured using 3D printing technologies. The relevance of the topic stems from the growing demand for functional parts capable of withstanding various mechanical loads. Special attention is given to the selection of high-performance materials, including reinforced polymers and metals. Parameters such as tensile strength, flexural strength, impact toughness, Young's modulus, and elongation at break are analyzed. Comparative data on the properties of various materials, including polymers reinforced with carbon or Kevlar fibers, are provided. Practical aspects of improving the strength of 3D-printed parts are discussed, including optimization of print settings, model orientation, infill density, and thermal post-processing (particularly annealing). The article concludes that material selection should be guided by the nature of expected loads, and offers recommendations for designing structurally robust components. The findings may be useful in the development of durable and reliable parts in the field of additive manufacturing.
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