Vol 62, No 4 (2019)

The results of investigations of low-voltage burning modes of a non-self-sustained glow discharge with a ~0.2 m³ hollow cathode at low (≈1 Pa) pressure, which is assisted by an external injection of electrons from the electric-arc plasma. The current-voltage characteristics recorded at low burning voltages 20–80 V demonstrate that there is a threshold glow-discharge burning voltage, at which a stepwise transition takes place from the burning conditions with high plasma inhomogeneity to the conditions of homogeneous plasma glow in the entire volume of the hollow cathode. This transition, accompanied by an enhanced hollow-cathode effect, is characterized by a 20–40% increase in the main discharge current. The glow discharge burning voltage, at which this current jump takes place lies within the range 45–60 V and depends on the value of the auxiliary discharge current and working pressure.

Using the wave functions of the quantum chemical INDO method, the molecular electrostatic potential (MESP) of hydroxyl substituted benzaldehydes and related compounds exhibiting the ability to inhibit the reproduction of the herpes simplex virus type I has been calculated. It has been established that the degree of biological activity correlates not only with the magnitude of the proton-acceptor capacity of the substituted, but also with the geometry of biologically active molecules. The correspondence between the MESP values of hydroxyl groups and the effectiveness of the inhibitory ability of the investigated substitutions has been established.

Results of measurements of the conductivity in the laser radiation propagation channel not only in laboratory, but also outdoors for laser radiation focused in the free atmosphere are presented. An experimental setup and geometry are described. The possibility of forming ionized channels with enhanced conductivity in the atmosphere using relatively low-energy beams of CO₂ lasers is shown.

A possibility of manufacturing ⁹⁹Mo via a nuclear reaction with ⁹⁶Zr (α, n) in the R-7 cyclotron of the Tomsk polytechnic university is investigated. The beam energy of α-particles is 27 MeV for the beam current values 13, 15 and 22 μA. The targets are manufactured from natural zirconium shaped as disks measuring 30 mm in diameter and 1.5 mm in thickness. As a result of the experiments the designed yield of ⁹⁹Mo is found to be on the order of (1.62 ± 0.15) (MBq/(μA·h) for ⁹⁶Zr targets with 100% enrichment, which closely agrees with the yields reported by other authors. It is shown that a sufficient amount of ⁹⁹Mo can be output for technetium-99m to be manufactured at a regional level.

A detailed analysis of the phase trajectories of cosmological models based on classical and scalar fields near surfaces of zero effective energy has been carried out. A study of the differential parameters of the convergence of phase trajectories to a zero-energy surface boundary shows that the phase trajectories merge within a finite time with the phase trajectories of free oscillations corresponding to zero effective energy. This confirms the assumption formulated in a number of previous works by one of the authors about the existence of Euclidean limit cycles in cosmological models based on scalar fields with a Higgs interaction potential.

It is shown that in classical physics there is a time analog of a spatial quantum-mechanical problem with periodic boundary conditions. On this basis, it is shown that the corresponding energy quantity has a band structure.

Electrical and thermal properties of single crystalline and extruded samples of a p-type Bi0.5Sb1.5Te3 solid solution with various grain sizes are studied in a wide temperature range of 80–300 K. It is revealed that the grain sizes significantly affect the values of the thermal-e. m. f. (α), electrical conductivity (σ), and thermal conductivity (χ) coefficients of the samples under study.

Dissipation of the kinetic energy of accelerated charged particles during their motion in the material causes its response to the external radiation effect, which, in turn, can significantly affect the kinetics of mass transfer. The effect of the electron flow and non-equilibrium phonons formed in the gradient field of temperature on the defect migration is considered for the first time. The heating temperature is calculated nearby the ion track as well as gradients of temperature and forces affecting the interstitial atoms and their migration.

The influence of thermomechanical treatments, including low-temperature and subsequent warm deformation, on the microstructure and mechanical properties of an austenitic reactor steel (Russian Grade EK-164) is investigated. It is shown that low-temperature plastic deformation (after cooling in liquid nitrogen) gives rise to the formation of a high density of microtwins. In the course of subsequent warm deformation (at T = 600 or 700° C) the localized deformation bands, having an internal fragmented nano-sized structure, propagate in the microtwin structure. It is demonstrated that these microstructure characteristics ensure a multiple (by 3–5 factors) yield strength increase at 20 and 650°C.

The Adomian decomposition method is applied to construct an approximate solution of the generalized one-dimensional Fisher–Kolmogorov–Petrovsky–Piskunov equation describing the population dynamics with nonlocal competitive losses. An approximate solution is constructed in the class of decreasing functions. The diffusion operator is taken as a reversible linear operator. The inverse operator is presented in terms of the diffusion propagator. An example of the approximate solution of the Cauchy problem for the function of competitive losses and for the initial function of the Gaussian type is considered.

The paper presents a study of the phase composition, morphology, magnetic and electromagnetic properties both of Y-type hexaferrites Ba₂Ni_2–xCu_xFe₁₂O₂₂ (x = 0.4, 1.0, 1.2) and composites produced therefrom. Hexaferrites are synthesized via standard ceramic method. Ferromagnetic resonance technique is applied to measure the magnetocrystalline anisotropy of synthesized hexaferrites. The spectra of permeability and permittivity and the frequency dependences of the reflection coefficients of composite materials are studied at the microwave frequency band. It is shown that these materials can be used in the production of radarabsorbing materials and coatings in the frequency range of 3.5–12.2 GHz.

Within the framework of the variational method, as the result of a numerical calculation we have found the energy of the excited state and the screening constant of the helium atom in the electron configuration 1s 2s, which is metastable with respect to the single-photon transition to the 1s² state, and also in the 1s 3s configuration. The results of numerical calculation of the energy are in approximate agreement with other values given for these states in the literature which are available to us. For the first time, numerical calculations have also been carried out for 1s ns configurations in the range of values n = 4, …, 9, in which the corresponding values of the energy E_n and the screening constant σ_n were obtained. It was found, in particular, that σ_n and |E_n| for the excited states in the range n = 2, 3, …, 9 fall monotonically with increasing n, where σ_n → 0 in the formal limit n → ∞, and E_n tends to the energy of a hydrogenlike atom with nuclear charge (2e), as it should be in accordance with the physical meaning of these quantities. The results of the calculations are illustrated graphically. The present study has important methodological significance in terms of the development and application of the basic principles of quantum mechanics to the helium atom.

In the present work, new robust adaptive estimates (AE) and confidence intervals have been synthesized for quantiles of physical quantity distributions based on the maximum likelihood method. The AE relative efficiency and a number of the classical and robust estimates have been found by the statistical simulation method on classes of the Tukey local and global supermodels. It is demonstrated that the efficiencies of the adaptive estimates and of the confidence intervals of the distribution quantile are significantly higher than those of the classical parametric, nonparametric, and robust estimates.

The paper describes the technology of surface doping of the X-cut plate of lithium niobate by high-temperature diffusion of copper ions from a metal film. The results of experiments on aggregation of dielectric nanoparticles on the surface of the sample by electric fields of photorefractive holographic gratings formed due to the photovoltaic mechanism by laser beams with a wavelength of 532 nm are presented.

The physical principles of formation of phase composition and defect substructure of a surface alloy in a low-stability state formed as a result of irradiation of the film (Si) - substrate (Grade 3 steel) system with a high -intensity electron beam are revealed. The formation of a multiphase submicro- and nanocrystalline layer is observed. It is shown that irradiation of metals and alloys with a pulsed electron beam in a regime of the surface-layer melting followed by high-rate crystallization frequently gives rise to the formation of local low-stability regions exhibiting a tendency towards the formation of metastable states up to amorphization of the material. A treatment regime is identified, which allows increasing the material microhardness and wear resistance by about 3 and 7.5 factors, respectively.