PHYSICS & SPACE SCIENCES
BAKU STATE UNIVERSITY JOURNAL of
PHYSICS & SPACE SCIENCES
ISSN: 3006-6123 (ONLINE);     

Current issue

Current issue: 2024, vol.1, issue 2


Current articles

Spatial structure of the heptapeptide molecule
Published: 21-Jun-2024Download PDF
Larisa I. Ismailova; Namik A. Akhmedov
Abstract
Studying the three-dimensional structure of peptide molecules is important when creat-ing new drugs. Peptides are the human body’s own resource. Understand the mecha-nism of action of these molecules can be, if you solve the problem of their structural and functional activity. Nociceptins are a new type of regulatory peptides of medical interest. Natural nociceptin reduces motor activity, causes a stress response and modu-lates spatial attention. This work is devoted to determining the spatial structure and conformational possibilities of the heptapeptide molecule with the amino acid sequence H-Phe1-Gly2-Gly3-Phe4-Pro5-Gly6-Pro7-OH. It is one of the recently synthesized ana-logues of nociceptin. It was found that the N-terminal tripeptide and tetrapeptide of this molecule are active and very important. Using the method of molecular mechanics, the spatial structure and conformational properties of the heptapeptide molecule were determined. The potential energy of this molecule was estimated as the sum of non-valent, electrostatic, torsion interactions and the energy of hydrogen bonds. 11 low-energy conformations were found for heptapeptide, the values of the dihedral angles of the main and side chains, and the energy of intra- and inter-residue interactions was estimated. It is revealed that low energy conformations of this molecule have the half-folded and folded type of backbone. The side chains of the Phe1 and Phe4 amino acids in low-energy conformations carry out effective interactions and are conformationally labile amino acids, they bring together the regions of the main chain and the side chains of the amino acids included in the heptapeptide. These folded forms bring parts of the backbone and the side chains of the amino acids together, and they result in convenient interactions.
Laser ablation Si thin films
Published: 22-Jun-2024Download PDF
Vusal U. Mammadov
Abstract
The processes of ablation of the surface of single-crystal silicon wafers and the properties of materials obtained because of silicon ablation under irradiation with a scanning beam with a wavelength of λ = 1062 nm were studied with varying laser radiation power and scanning modes. The range of beam scanning modes in which SiO_2 layer growth is observed has been established. Starting from a scanning speed of 2000 mm/s, the formation of silicon oxide stops, and because of the destruction of silicon, nanometer-sized silicon particles are formed. In this case, the destruction of silicon is accompanied by sounds of different frequencies, depending on the scanning speed.th
Ab initio calculation of electronic band structure of Cd1-XFeXSe
Published: 23-Jun-2024Download PDF
Matanat A. Mehrabova; Elshad A. Allahyarov; Niyazi H. Hasanov; Nurana R. Gasimova;
Abstract
The purpose of this work was to calculate the electronic band structure of Cd1–xFexSe. Ab initio, calculations are performed in the Atomistix Toolkit program within the Densi-ty Functional Theory and Local Spin Density Approximation on Tight Tiger basis. We have used Hubbard U potential UFe = 2.42eV for 3d states for Fe ions. Supercells of 8 and 64 atoms were constructed. After the construction of Cd1–xFexSe (x=6.25%; 25%) supercells, atom relaxation and optimization of the crystal structure were carried out. Electronic band structure, and density of states were calculated, and total energy have been defined in antiferromagnetic and ferromagnetic phases. The band gap for the Cd1-xFexSe, x=0.06 in ferromagnetic phase is equal to Eg= 1.77 eV, in antiferromagnetic phase Eg=1.78 eV. For x=0.25 Eg= 1.92 eV. Antiferromagnetic phase considered more stable. Our calculations show that the band gap increases with the increases in Fe ion concentration.
Study of particle acceleration mechanisms in the anisotropic solar wind
Published: 24-Jun-2024Download PDF
Mirnamik M. Bashirov
Abstract
Compton and inverse Compton effect in solar wind plasma, equations obtained on the basis of magnetohydrodynamic theory for one-particle plasma were investigated. The radial dependences of the solar wind speed were obtained and analyzed using MHD equations. The results are important in explaining the acceleration mechanism of cosmic plasma particles, in studying the evolution process of the Sun and stars, as well as in the study of the factors affecting the operation of radio electronic control devices.
Prompt photon production in the bremsstrahlung at NICA energies
Published: 25-Jun-2024Download PDF
Mohsun R. Alizada; Azar I. Ahmadov; Andrey B. Arbuzov
Abstract
The differential cross-section of prompt photon production in the subprocess of bremsstrahlung qq→qqγ of proton-proton collisions at energies √s=10 GeV has been determined without and taking into account of longitudinal polarization of colliding particles. The dependence of differential cross section of bremsstrahlung process on the energy of the colliding particles √s, the transverse momentum pT, the cosine of the scattering angle Cos(θ), the rapidity y of photon and xT has been investigated. The ratio of the differential cross section of bremsstrahlung to the sum of the differential cross sections of Compton scattering of a quark-gluon, annihilation of a quark-antiquark pair, and bremsstrahlung is 0.03%.
Temperatures of the central stars of planetary Nebulae NGC 2392, NGC1535, NGC 3242, IC 418
Published: 26-Jun-2024Download PDF
Aynur H. Alili; Kamala I. Alisheva; Khidir M. Mikailov
Abstract
According to the HeII lines, Zanstra temperatures were calculated of the central stars of planetary nebulae NGC 2392, NGC 1535, IC 418, NGC 3242. Respectively, the tempera-tures of 83596 K, 70079 K, 44061K and 87858 K were found for the central stars. The flux in the HeII radiation line used in the calculations have determined from the spectra taken from the archive of the European Southern Observatory. With this aim, were pro-cessed the spectra of the studied nebulae, energy distribution curves in absolute flux units according to magnitude were constructed in different filters (UBVR), determined the equivalent widths of the HeII lines and the values of the fluxes in the continuum near the line. The temperatures obtained from the calculations are listed in comparison with the temperatures obtained by other authors.
Photoluminescence spectra of polycrystalline CVD ZnSe when changing the wavelength of excitation light
Published: 27-Jun-2024Download PDF
Musavar A. Musayev; Jahangir I. Huseynov; Dunyamaddin J. Askerova; Ibrahim I. Abbasov; Aynura A. Hadiyeva; Aitaj J. Mammadova; Narmin N. Hasimova
Abstract
In this work, we investigated the photoluminescence spectra of polycrystalline CVD ZnSe observed by stepwise variation of excitation energy in the region of the fundamental absorption edge, first from 420 nm to 455 nm in 5 nm steps, then 10 nm from 455 nm to 475 nm and finally 20 nm from 475 nm to 515 nm.
Synthesis of nickel nanoparticles with magnetic properties using the carbothermy method
Published: 28-Jun-2024Download PDF
V.A. Bohatyrenko; Dmitry S. Kamenskyh; Maarif A. Jafarov; Tatiana V. Tkachenko; Vitalii O. Yevdokymenko
Abstract
The article discusses a method for producing nickel-based nano-microparticles with magnetic properties using the carbothermic reduction of precursors - nickel hydroxides. The possibility of a fairly simple and labor-intensive method for producing nickel (II) hydroxide by contact precipitation from a nickel-containing electrolyte on the surface of magnesium particles has been demonstrated. The method is based on the formation of local corrosive microgalvanic cells with predominant hydrogen depolarization. Both precursors and magnetic nickel powders were analyzed by SEM microscopy, X-ray dif-fraction and X-ray fluorescence analyses. Using the SEM microscopy method, it was found that, depending on the surface structure of the reducing agent particles, both lamellar structures of α/β-Ni(OH)2 and three-dimensional (3D) micro-nanostructures flower-like of β-Ni(OH)2 with varying degrees of crystallinity can be obtained. Thermal reduction annealing of α/β-Ni(OH)2 using the carbothermic method makes it possible to obtain a non-pyrophoric highly dispersed magnetic nickel-containing powder in a com-posite with microparticles of porous carbon, stabilized by the kotoite phase.
Viscous flow and thermal characteristics of N-Amyl alcohol
Published: 29-Jun-2024Download PDF
Bakhtiyar G. Pashayev; Mammad R. Rajabov; Aida B. Ahmadova; Nilufar F. Orujova
Abstract
Based on experimental values of dynamic viscosity and density of n-amyl alcohol in the pressure range of 11.09 MPa-49.14 MPa and temperature range of 288.95 K-567.35 K the activation Gibbs energy of viscous flow, the activation enthalpy of viscous flow, the activation entropy of viscous flow, the isobaric expansion coefficient and the isothermal compression coefficient were calculated and the changes of these parameters depending on temperature and pressure were analyzed. It was determined that with the increase in temperature at a given pressure, the activation Gibbs energy of viscous flow first decreases and then increases, the activation enthalpy of viscous flow and the activation of entropy of viscous flow only decrease, and the isobaric expansion coefficient and isothermal compression coefficient only increase.
Could quark stars be a source of ultra high energy cosmic rays
Published: 30-Jun-2024Download PDF
Mais K. Suleymanov
Abstract
The origin of cosmic rays with ultra-high energies (UHE) remains mystery.In our paper*, we have discussed whether dense quark matter – quark-gluon plasma, formed in the centers of neutron stars or Quark Stars (QS), could be a source of these UHE cosmic rays. QS, in particular, are more likely candidates for being the source of UHE cosmic rays, although for a long time, they remained unobserved. A recent study** proposed that the low-mass companion of the black hole in GW190814 might be a strange quark star. In the talk we continue to discuss that the QS’s matter, could be a source of the UHE particles. Results from the RHIC and LHC experiments on ultrarelativistic heavy ion collisions suggest that the quark-gluon matter produced in such collisions displaying collective behavior. This behavior could lead to the formation of a coherent group of partons (CGP). A collision between a parton and the CGP, similar to a photon colliding with a high-energy electron, could result in the parton gaining energy through the in-verse Compton effect, thereby accelerating without an external field.
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