卷 62, 编号 2 (2019)

Quasi-resonant parametric decay of a magnetoacoustic wave into two Alfvén waves in a heat-releasing plasma is considered. It is shown that in the case of isentropical instability under the resonant conditions (zero frequency detuning) the Alfvén waves undergo bi-exponential amplification. The presence of frequency detuning prior to this amplification gives rise to parametric modulation of the Alfvén wave amplitude, whose duration increases with detuning. A boundary frequency detuning is determined, at which there is no amplification of the Alfvén waves.

The results of topological characteristics for the cases of a critical state of inert gases and a two-stage condensation of low-temperature helium are obtained. The unsatisfiability of Trouton’s rule is proven for the critical state of helium. The results of calculations of the velocity of light propagation in vacuum and the formulas for calculating the largest and smallest sizes of nano- and microparticles of a substance, at which their extraordinary properties are manifested compared to a bulk body, are reported.

The precession of the perihelion of Mercury’s orbit is simulated numerically within the framework of the generalized law of universal gravitation in the field of the Sun and planets taking into account the ellipticity of the planet orbits and new data on the flattening, the mass of the Sun, and the gravitational constant. Calculations were carried out with increased accuracy (up to 19–20 decimal places) and iteration steps of 0.00005 s and 0.0001 s starting from the asteroid belt. It has been shown that the average precession of the perihelion of Mercury’s orbit in 100 years calculated within the framework of the generalized law of universal gravitation and averaged over long time periods from several hundred years to several thousand years taking into account the ellipticity of planet orbits is ~554.2”. This is less than the observed shift of the perihelion of Mercury’s orbit by ~19.9”. As is well known, the observed shift is ~574.1”. That is, the question on the adequacy of the generalized law of universal gravitation to the observances still remains open. However, it is possible that an object of small size (or several such objects) may be located inside Mercury’s orbit, and one more object, whose mass should not exceed at least ~0.2 of the Earth mass may be located at the diametrically opposite point of the Earth orbit behind the Sun. The results obtained are valid to within 1–2 decimal places.

In this paper, general analytical expressions are obtained for the differential elastic scattering cross sections of two nuclear particles with allowance for spin-orbit splitting for channels with the half-integer spins 3/2 and 5/2, which are parameterized with respect to the orbital quantum number l. This representation makes it possible to take into account explicitly a definite, energy-dependent number of scattering partial waves and to consider the relative contribution of each partial wave. The obtained expressions can be used when performing phase shift analysis in elastic scattering of nonidentical particles, for example, N²H, N⁶Li, ²H⁷Li, and ²H⁹Be at low energies.

The results of measurements of three tensor analyzing power components of the reaction of incoherent photoproduction of a π⁰-meson on a deuteron in the ranges of proton and neutron energies, 15–200 and 15–150 MeV, respectively, are presented. The experiment is performed on an internal tensor-polarized gaseous deuterium target of a VEPP-3 electron storage ring using the method of proton and neutron coincidence counting. The results of measurements of tensor analyzing power components are compared with those obtained by statistical modeling performed within a theoretical model.

From the viewpoint of general relativity theory (GRT), the obstacles are discussed that do not allow gravitational and electromagnetic fields to be used to create a model of elementary particles and atomic nuclei, including vanishingly small gravitational interaction in comparison with electromagnetic one on microcosm scales, incomplete geometrizability of the electromagnetic field itself, its long-range action in comparison with short-range action of nuclear forces, and the Coulomb repulsion of likely charged protons in a nucleus (it seems so natural that it cannot provide focusing of nucleons and holding nuclei in a compact state) – all these phenomena are differently interpreted in GRT primarily due to universality of gravitational interaction that plays the dominant role at any micro- and macrocosm scales. Based on exact solution of the Einstein–Maxwell equations for a centrally symmetric free electromagnetic field and a dust-like substance, gravitational models of a proton, an electron, and a neutron are suggested in the form of pulsing unclosed wormholes with two static necks – electric charges of opposite signs – emerging into two parallel asymptotically flat vacuum spaces. The neutron is represented in the form of a double wormhole. The calculated radii are 0.8412 fm for the proton, 386.17 fm for the electron, and 1.0049 fm for the neutron. The proton radius coincides within 4% with its experimental value equal to 0.8409 fm measured from the Lamb shift of muon-hydrogen. The electron radius is 459 times greater than the proton radius. However, when the proton is scattered on the electron, its wormhole penetrates into the center of the electron wormhole, the curvature radius of its neck decreases down to the above-indicated neutron radius at the expense of a portion of the relativistic rotational proton energy and the energy of the curved space, that is, the energy of the gravitational field transferred to the electron.

A classification is performed of the spaces with plane-wave metrics in accordance with the presence of three-dimensional subgroups of the group of space-time motion with three-dimensional spatial orbits. In order to obtain spatially-homogeneous models, exact solutions to Einstein’s vacuum equations are found. To obtain these solutions, the Petrov and Bianchi classifications are performed. The results obtained on the classification of the plane-wave metrics using the assumed or three-dimensional subgroups of the group of motion with three-dimensional spatial orbits can be used for any metric gravitational theories.

The absorption activity of silver nanoparticles (AgNPs) on the surface of fibers of natural and artificial origin is estimated. In addition, it is determined that the sorption activity of natural or artificial fibers with respect to silver nanoparticles depends on their size, fabrication method, and properties of the gelling agent. It is found that the highest absorption of silver nanoparticles is observed when using natural silk fibers, which possess a significantly higher activity as compared with an artificial fiber (fluoroex).

The paper presents modeling and simulation of the Gruneisen parameter depending on the volume and temperature using the principal Hugoniot, isentropes and the Gruneisen parameter at the initial density. The evaluation of the Gruneisen parameter for gold and silver is carried out in a wide parameter range. The Gruneisen parameter is compared with the results obtained by other researchers. The proposed modeling procedure differs from early-published results by the absence of groundless assumptions. The approximate dependencies are suggested for the Gruneisen parameter, the cold equation of state and the shock velocity on the particle velocity within the wide range of parameters.

Fourier spectra of the C₂D₄ molecule in the region 2250–3040 cm^–1, in which the fundamental ν₉ band and the combinational ν₂ + ν₇ + ν₈ band are located, are studied. The parameters of the effective Hamiltonian of the (v₉ = 1) and (v₂ = v₇ = v₈ = 1) states of the C₂D₄ molecule are determined based on the analysis of the experimental data.

Using the results of a paper previously published by the author, general expressions have been obtained for the energy and screening constant for a two-electron atom for arbitrary sets of quantum numbers of the electrons. In the particular case of the ground state of the atom, the well-known classical result is obtained from the general formulas.

The current-voltage characteristics and admittance of multilayer structures for organic LEDs based on the PEDOT:PSS/NPD/YAK-203/BCP system have been experimentally investigated in a wide range of the measurement conditions. It is shown that at voltages corresponding to the effective radiative recombination of charge carriers, a significant decrease in the differential capacitance of the structures is observed. The frequency dependences of the normalized conductance of LED structures are in good agreement with the results of numerical simulation in the framework of the equivalent circuit method. Changes in the frequency dependences of the admittance with a change in temperature are most pronounced in the temperature range of 200–300 K and less noticeable in the temperature range of 8–200 K. From the frequency dependences of the imaginary part of impedance, the charge carrier mobilities are found at various voltages and temperatures. The mobility values obtained by this method are somewhat lower than those determined by the transient electroluminescence method. The dependence of the mobility on the electric field is well approximated by a linear function. As the temperature decreases from 300 to 220 K, the mobility decreases several times.

An analysis of the influence of a deviation of atomic composition from stoichiometry performed by the Monte Carlo method using a NiAl intermetallide as an example in the course of its cooling demonstrates that such deviation is an important factor in the region of pretransitional low-stability structural-phase states preceding transformation. The short-range order parameter values in non-stoichiometric alloys in their absolute values are essentially lower than those of a stoichiometric intermetallide; hence the tendency towards atomic ordering in non-stoichiometric intermetallics is noticeably lower than that in the stoichiometric alloys. The behavior of the temperature plots of the long-range order parameter in non-stoichiometric alloys during their cooling is considerably different from that of a stoichiometric intermetallide. In the case of cooling of non-stoichiometric alloys, a considerable degree of overcooling is required for the long-range order to set, and the formation of ordered phases occurs at much lower temperatures. Moreover, the temperature plot of long-range parameter of the Ni45Al55 alloy lies somewhat lower than that of the Ni₅₅Al₄₅ alloy, which implies that setting of the longrange order in these non-stoichiometric alloys occurs in different ways. It is underlined that a deviation of the system’s composition from stoichiometry gives rise to an essential refinement of the ordered and disordered regions.

The paper presents a theoretical study of the harmonic power evolution in a single-pass free-electron laser (FEL) and a comparison with some of the experimental results. The phenomenological approach which considers the main FEL parameters (current density, the Lorentz factor, electron energy spread, and the beam geometry) provides a description of any undulator. With due regard to the real laser beam parameters, the effect from high-order harmonic radiation and the beam deviation from the undulator axis on the FEL irradiation is investigated. The Bessel coefficients are calculated for the undulator in the presence of the second periodic field. The phenomenological approach provides the free-electron laser simulation experiments at Sorgente Pulsata Auto-amplificata di Radiazione Coerente (SPARC), SPring-8 Angstrom Compact Free-Electron Laser (SACLA) and Linac Coherent Light Source (LCLS). These studies include the high-harmonic generation, a comparison of the emission power evolution with the experimentally obtained data on the harmonic generation including even and odd high-order harmonics, gain and saturation lengths and the respective power. A possible effect from the third harmonic of the planar undulator magnetic field is studied in relation to the FEL irradiation. It is shown that this effect is insignificant even at the magnetic-field harmonic amplitude equaling ~1/10 of the amplitude of the ideal magnetic field in the periodic undulator. It is found that the second-harmonic generation in FEL lasing is rather weak, that is in good agreement with the measurement results as well as the behavior of the high-order harmonics.

The spectrum of the cis-ethylene-d2 molecule (C₂H₂D₂-cis) has been recorded with a Bruker IFS 120 HR Fourier spectrometer in the wavelength region 1100–2000 cm^–1 with a resolution of 0.0025 cm^–1. The region 1620–1780 cm^–1, in which the weak 2ν₇ (А1) and ν₆ + ν₁₀ (В₁) bands with centers at (1685.28900 ± 0.00069) cm^–1 and (1698.06400 ± 0.00033) cm^–1 are located, is considered. These bands have not been analyzed previously and are studied in the present work for the first time. The spectroscopic parameters are fitted using energies of 164 upper levels corresponding to the examined states. As a result, 10 parameters of diagonal blocks of the effective Hamiltonian describing the rovibrational structures of the 2ν₇ and ν₆ + ν₁₀ bands and 5 resonance parameters of the c-type Coriolis interaction are obtained.