Journal of Contemporary Physics (Armenian Academy of Sciences)最新文献

Expressions for the phase of a spherical wave in the near, middle, and far zones of observation are obtained. It is proved that in the Fresnel approximation a spherical wave is approximated by a paraboloid wave, which in its turn is approximated by a plane wave in the Fraunhofer approximation. Based on this, the problem of the description of a wave field generated by a system of many coherently radiating point sources is considered. An expression is obtained for the intensity distribution in the interference problem for the near-field approximation. It is shown that the distribution of intensity maxima is determined by solving a cubic equation, which, in the Fresnel approximation, transforms into a linear equation expressing the classical result on a uniform distribution of intensity maxima.

Samples of natural zeolite from the Nor-Kokhb deposit (Armenia), as well as its chemically and thermally modified by the microwave method in comparison with the traditional method, were studied. It was shown that the process of microwave processing proceeds 3 times faster than the traditional one. X-ray diffraction analysis shows that the main mineral in the zeolite samples under study is clinoptilolite. According to the results of optical and EPR spectroscopy, the presence of Fe³⁺ ions in the framework and extraframework positions of the zeolite was revealed. The study of diffuse reflection spectra allows to conclude that zeolite is a wide-band material with a bandgap of 4.14 eV.

We propose in this paper a method for the synthesis of α-WC powder by the method of electric spark discharge, where WC–8% Co (anode) and W (cathode) are used as electrode materials, and deionized water is used as a dielectric liquid. The synthesized powder was subjected to thermal annealing after drying in an air atmosphere at temperatures of 250, 400, and 600°C for 2 h in order to analyze its thermal stability and identify possible temperature-dependent phase transitions. The phase composition, morphology, and particle sizes of the synthesized powder and powders subjected to thermal annealing were studied by powder X-ray diffraction and scanning electron microscopy. The synthesized powder contained two phases: the dominant α-WC phase and the α-W₂C phase. Both α-WC and α-W₂C phases almost completely transformed into the CoWO₄ phase at an annealing temperature of 600°C. The processes of formation of the phase components of the synthesized powder and the transition of these components to the CoWO₄ phase as a result of thermal annealing are discussed.

The densities of a water-salt solution without and a water-salt solution with DNA were studied depending on the concentration of NaCl in the solution when they were irradiated with millimeter electromagnetic waves of non-thermal intensity, which are resonant for vibrations of hexagonal water molecular structures with a frequency of 50.3 GHz. Studies have shown that the density of solutions increases with irradiation. Density change due to irradiation is minimal for 0.9% NaCl solution (saline). Viscometric measurements have shown that irradiation (which leads to dehydration of DNA) does not lead to a noticeable change in the secondary and tertiary structure of DNA for a physiological solution of DNA.

Conventional glucose testing methods require the analysis of a droplet of blood from the patient’s finger, which is painful and inconvenient. Such a one-time method carries an infectious risk and is not suitable for the long-term, daily continuous glucose monitoring often required today. Continuous glucose monitoring can provide timely information about the success of therapy during treatment and make appropriate adjustments. Currently, there is no single method of continuous monitoring. Currently, there is no single method of continuous monitoring. Glucose concentrations, although different kinds of non-invasive sensors have been developed for such monitoring on different physical principles. Such devices can provide painless, risk-free, inexpensive and frequent testing. This article discusses recent advances in non-invasive glucose control techniques.

Oriented liquid crystal (LC) cells in crossed polarizers without applying voltage have a uniform appearance. But when a voltage is applied, a mosaic texture with sections of different orientations of LC molecules can be observed. The smooth and consistent movement of the air bubble, was formed at the LC cell making, allows for obtaining a uniform orientation pattern. It is shown that the bubble’s surface tension is comparable with the force of LC molecules anchoring with orienting layer.

The paper briefly describes the projects for the modernization and modification of the Yerevan Electron Synchrotron ARUS of the A. Alikhanyan National Science Laboratory (Yerevan Physics Institute). The described work proposed in different years is of interest related to the discussion of the issue of creating a new accelerator base in Armenia for solving actual applied and fundamental physical problems.

The quantum dynamics of the number of photons, of the quantum entropy, and the Wigner functions of field interacting modes are studied for the process of non-degenerate parametric decay in an optical cavity, where a quantum with energy (hbar {{omega }_{3}}) decays into two photons with energies (hbar {{omega }_{2}}) and (hbar {{omega }_{1}}) ((hbar {{omega }_{3}} = hbar {{omega }_{2}} + hbar {{omega }_{1}})). It is shown that the mode with frequency ({{omega }_{3}}) can localize in a squeezed state in the region of very strong coupling between the interacting modes, and the modes with frequencies ({{omega }_{1}}) and ({{omega }_{2}}) localize in states that are statistical mixtures of Fock states regardless of the value of the coupling coefficient

Theoretical study of spectroscopic properties of LiNbO₃:Er³⁺ crystal in the wavelength range of 1470–1635 nm was carried out taking into account the Stark structure of the optical spectrum of the impurity ion. Wave functions of the Stark sublevels of both ground ({}^{4}{{I}_{{15/2}}}) and first excited ({}^{4}{{I}_{{13/2}}}) manifolds of the Er³⁺ ion were constructed in the LSJM representation, line strengths induced by indirect electric-dipole inter-Stark transitions were computed, and the main spectroscopic characteristics of emission and absorption spectra of impurity ion were determined.