卷 43, 编号 5 (2017)

The formation of ion products of single and dissociative ionization of a valine molecule (C₅H₁₁NO₂) by high-energy (11.5 MeV) and low-energy (below 150 eV) electrons has been investigated by mass spectrometry. Mass spectra of this molecule and near-threshold functions of yield of its ion fragments, for which the magnitudes of occurrence energies are determined, have been obtained. The analysis of the changes in mass spectra of valine molecules irradiated with doses of 5 and 20 kGy in comparison with those for unirradiated molecules shows that high-energy irradiation changes irreversibly the structure of some of the initial molecules.

A detailed study of the paramagnetic properties of silicon nanoparticles obtained by laser-induced pyrolysis of monosilane is carried out by the method of electron-paramagnetic-resonance spectroscopy as dependent on the conditions of subsequent processing and storage. Defects of the P_b0-, P_b1-, and D-center types are detected, and their parameters and concentration values are determined. It is established that the defects in the studied structures are centers of nonradiative recombination. It is shown that, to obtain samples with low concentrations of paramagnetic centers and stable luminescence, the procedure of etching the original silicon nanoparticles in an aqueous solution of HF and HNO₃ acid followed by natural oxidation under normal conditions can be used.

For digital magnetic recording of encoded information with longitudinal magnetization of the tape, the connection between the domain structure of a storage medium and magneto-optical image of its stray fields obtained using a magnetic film with a perpendicular anisotropy and a large Faraday rotation has been studied. For two-frequency binary code without returning to zero, an algorithm is developed, that allows uniquely decoding of the information recorded on the tape based on analysis of an image of stray fields.

The curves of thermally stimulated luminescence of Gd₃Ga₃Al₂O₁₂:Ce³⁺ ceramics (a nominally pure sample and samples doped with rare-earth ions) are measured in the temperature range of 80–550 K. The depth and the frequency factor of electron traps established by Eu and Yb impurities are determined. An energy-level diagram of rare-earth ions in the bandgap of Gd₃Ga₃Al₂O₁₂ is presented.

The secondary ion mass-spectroscopy technique was used to study the results of hydration of borosilicate, aluminosilicate, and soda-lime silicate glasses in ¹H₂¹⁸O water vapor containing 97% of the isotope ¹⁸O. It is shown that hydration of the surface of the soda-lime silicate glass occurs as a result of the ion-exchange reaction with alkali metals. In the case of borosilicate and aluminosilicate glasses, water molecules decompose on the glass surface, with the observed formation of hydrogenated layer in the glass being the result of a solid-state chemical reaction—presumably, with the formation of hydroxides from aluminum and boron oxides.

The process of the appearance of forced rotation of an axial core mounted in a modified vortex tube in the direction opposite to the rotation of the air vortex and the precession of its axis have been studied. It has been established that dynamical bending of a metal axial core arises in the process of rotation which causes mechanical wear of its end part and fracture in the fastening area of the bearing without residual curvature of the core axis. The excitation of rotation and observed force effects are not related to the mechanical action of rotating air flow on the axial core.

Barrier-discharge stimulation of chemical reactions has been studied in the case of methane oxidation by atmospheric oxygen with the formation of carbon monoxide and hydrogen. Experiments in a plasmachemical reactor demonstrated the possibility of increasing the yield of synthesis gas (syngas) by means of plasma pretreatment of the initial mixture of air and methane in a 7: 1 ratio at atmospheric pressure. The output-gas composition was determined by gas chromatography. It is established that the plasma-discharge treatment of the initial gas mixture leads to a 15% increase in the amount of syngas at the reactor output and increases the reaction selectivity with respect to hydrogen and carbon monoxide by 3.2 and 6.5%, respectively.

The influence of severe plastic deformation on the structural-phase state of grain boundaries in a Ti–4Al–2V (commercial PT3V grade) pseudo-alpha-titanium alloy has been studied. It is established that increase in the strength, plasticity, and corrosion resistance of this alloy is related to the formation of an ultrafine- grained structure. In particular, it is shown that an increase in the resistance to hot-salt intergranular corrosion is due to diffusion-controlled redistribution of aluminum and vanadium atoms at the grain boundaries of titanium formed during thermal severe plastic deformation.

We present a method for and results of determination of the field of integral density in the structure of flow corresponding to the Mach interaction of shock waves at Mach number M = 3. The optical diagnostics of flow was performed using an interference technique based on self-adjusting Zernike filters (SA–AVT method). Numerical simulations were carried out using the CFS3D program package for solving the Euler and Navier–Stokes equations. Quantitative data on the distribution of integral density on the path of probing radiation in one direction of 3D flow transillumination in the region of Mach interaction of shock waves were obtained for the first time.

We have studied the ability of a liquid-crystal (LC) matrix to visualize and orient DNA molecules. It is established that the relief of the interface between the LC mesophase and conducting contact can be improved without using an additional high-ohmic polymer layer. Spectroscopic and ellipsometric techniques revealed changes in the refractive properties and structure of composites. The obtained results can be used in creating devices for rapid DNA testing with retained form of biostructures.

The problem of current-density distribution over the surface of a microstrip dipole antenna conformally arranged on a dielectric cylinder is reduced to a singular integral equation with a Cauchy kernel. Patterns of current distribution on the antenna surface for various values of dielectric permittivity of the cylinder material are presented.

Isothermal turbulent flows in a layer of viscous incompressible fluid confined between counter-rotating spherical boundaries have been experimentally studied. The influence of modulation of the velocity of inner sphere rotation on the characteristics of turbulence is considered. Measurements of flow velocity were carried out by laser Doppler anemometer. A local minimum is found in the dependence of the magnitude of turbulent pulsations on the amplitude of velocity modulation. It is established that, in the absence of modulation, the slopes of velocity spectra are close to–11/5. Modulation amplitude enhancing can lead to the formation of velocity spectra typical to two-dimensional turbulence, with slopes of–5/3 at low frequencies and–3 at high frequencies.

The phenomenon of intermittent phase synchronization during development of epileptic activity in human beings has been discovered based on EEG data. The presence of synchronous behavior phases has been detected both during spike-wave discharges and in the regions of background activity of the brain. The degree of synchronism in the intermittent phase-synchronization regime in both cases has been determined, and it has been established that spike-wave discharges are characterized by a higher degree of synchronism than exists in the regions of background activity of the brain. To determine the degree of synchronism, a modified method of evaluating zero conditional Lyapunov exponents from time series is proposed.