Vol 60, No 7 (2017)

Effect of hydrogen in the concentration range from 10 to 2000 ppm on the characteristics of sensors based on thin films of tin dioxide modified with gold (Au/SnO₂:Sb, Au) is studied in the thermo-cyclic mode at temperatures from 623 to 773 K and absolute humidity from 2.5 to 20 g/m³. Experimental data are discussed using expressions obtained within the framework of a model that takes into account the presence of three types of adsorbed particles (O¯, OH, and OH¯) on the surface of SnO₂ nanocrystals. The characteristics of the sensors based on thin Pt/Pd/SnO₂:Sb films (the first series) are compared with those of Au/SnO₂:Sb, Au films (the second series). It is found that the degree of dissociation of molecular hydrogen into atoms during adsorption on the sensor under interaction with Au particles on the SnO₂ surface is 4 times greater than that under interaction with Pt/Pd particles. The degree of dissociation of H₂O molecules into hydrogen atoms and hydroxyl groups in pure moist air on the surface of the sensors of the second series is 1.6 times greater than that for the sensors of the first series. Thus, gold is a more effective stimulator of the dissociation of H₂ and H₂O molecules than platinum and palladium. A formula is obtained that describes more accurately the dependence of the response of the sensors of both series to the effect of hydrogen on the concentration of this gas and on the temperature of the measuring devices.

Time dependences in the thermo-cyclic mode of the conductivity of CO sensors, constructed in a traditional four-electrode and a planar three-electrode design on the basis of thin nanocrystalline tin dioxide films, are analyzed. The analysis showed that the use of the Pt/Pd/SnO₂:Sb sensors in a planar design in the thermocyclic mode with a long cooling cycle makes it possible to detect smoldering products at a significant reduction of power consumption.

The aim of this paper is to develop a method, described earlier, of solving quantum-mechanical problems into a universal numerical method of modeling fields of various physical nature. This method is based on reducing the initial equation of mathematical physics describing a given physical field to a simpler inhomogeneous equation with a known fundamental solution. This equation is then transformed into an inhomogeneous integral equation with a kernel expressed in terms of the known fundamental solution. The obtained integral equation with boundary conditions is solved numerically. To confirm the efficiency of the proposed numerical method, a two-dimensional and a three-dimensional boundary value problem with known solutions have been solved. Another important illustration of the efficiency of the proposed method is the solution of quantum-mechanical problems for one-dimensional and two-dimensional quantum oscillators. It is shown that the considered method allows one to find the energy eigenvalues and the eigenfunctions with acceptable accuracy.

Within the framework of the modified potential cluster model with classification of orbital states according to the Young tableaux and revised potential parameters for the ³He⁴He, ³H⁴He, and ²H⁴He cluster channels of the nuclei ⁷Be, ⁷Li, and ⁶Li, astrophysical S-factors of processes of radiative ³He⁴He capture from 20 keV, ³H⁴Hе capture from 10 keV, and ²Н⁴Не capture from 5 keV are considered. On the basis of the obtained results, the rates of all of the considered reactions are calculated in the temperature range from 0.05 to 5 T₉ and a comparison with the results of other authors is carried out.

An averaging of the equations of the standard cosmological model (SCM) is carried out. It is shown that the main contribution to the macroscopic energy density of the scalar field comes from its microscopic oscillations with the Compton period. The effective macroscopic equation of state of the oscillations of the scalar field corresponds to the nonrelativistic limit.

An estimate of the flux of prompt atmospheric neutrinos produced in decays of charmed particles is obtained. Cross sections of the production of charmed particles (D, Λ_c) in pA and πA collisions are calculated in the quark-gluon string model (QGSM) for the energy range 1 TeV – 100 PeV. New data on the cross sections of charmed meson production at high energies, obtained in experiments at the Large Hadron Collider, make it possible to refine the values of the free parameters of the QGSM and obtain a preliminary estimate of the prompt atmospheric neutrino flux. A comparison is made with the results of other neutrino flux calculations carried out for other charm production models – the dipole model and SIBYLL 2.3rc1.

High resolution spectrum of the ¹³С₂H₄ molecule recorded in the region of 1980–2080 cm^–1 with a resolution of 0.0025 cm^–1 using a Bruker IFS 120HR Fourier spectrometer is analyzed. As a result of solving the inverse spectroscopic problem, spectroscopic parameters of the vibrational state ( ν₆ = ν₁₀ = 1, B_3u) of the examined molecule are obtained for the first time that allows rotational energy levels to be reproduced with an accuracy close to the experimental one (a total of 677 rovibrational energies corresponding to 2300 transitions up to J^max = 40 and \( {K}_a^{\mathrm{max}}=15 \)).

The paper deals with the formation of the dislocation structure of a heavy-wall pipe made of dispersionhardened Cu-based alloy and subjected to the uniform internal pressure. The increasing generation of shear dislocations and prismatic dislocation loops lead to the expansion of the plastic range with the pressure growth. With increasing size of strengthening particles and decreasing distance between them, the elements of the dislocation structure begin to generate more intensively similar to the strength properties of the material.

The authors consider and evaluate the physical parameters and regularities of the process of consolidation of Fe–Cu, Cu–Nb, Ag–Ni, Fe–Pb nanoparticles when creating composite materials by means of shock wave compaction. As a result of theoretical consideration of explosive compaction process, researchers established and discussed the physical process conditions, established a number of threshold pressure values corresponding to different target indicators of the state of the compact. The time of shock wave impact on powders for powder consolidation was estimated.

Results of investigation of the plasma processes proceeding upon cooling of the heterogeneous low-temperature argon-oxygen arc discharge plasma in an external magnetic field are presented. The oxygen content is kept on the level insufficient for complete oxidation of carbon vapors. Upon cooling of the low-temperature plasma containing comparable amounts of C and Fe atoms, the dispersed particles containing mixed microcrystals of carbon and iron oxides are formed. The particles formed from Cu and SiO₂ vapors in the arc discharge plasma are also studied. It is established that in the presence of the external magnetic field, the dispersed particles of mixed C and Fe or Cu and SiO₂ microcrystals have larger sizes than the particles formed in the absence of the magnetic field.

New robust adaptive estimations (AE) of the shift and scale parameters are synthesized based on the weighted maximum likelihood method. The potential AE efficiencies are determined on classes of local and global Tukey distributions (supermodels). They are compared with the efficiencies of classical and robust estimations on the local and global supermodels of distributions. It is demonstrated that the efficiencies of the adaptive estimations of the shift and scale parameters are significantly higher than of the classical parametrical and robust estimations.

Within the framework of GRT, properties of stationary distributions of self-gravitating magnetic fields are considered under the condition that a vortex component is present in the gravitational field. It is shown that in this case, cylindrically symmetric configurations of the considered fields always lead to the formation of a wormhole geometry. The properties of such formations are investigated.

Colloidal solutions of nanoparticles (NPs) are prepared by nanosecond pulsed laser ablation (upon exposure to Nd:YAG laser radiation at a wavelength of 1064 nm with a pulse duration of 7 ns) of a copper target in water and ethyl alcohol. Their composition, structure, and optical properties are investigated. It is shown that monovalent Cu₂O NPs are mainly formed in water, whereas metal Cu NPs are mainly formed in ethanol. The nonlinear transmission of colloids at wavelengths of 532 and 1064 nm is investigated. It is established that they effectively limit the nanosecond laser pulse power at a wavelength of 532 nm.

The paper presents the results of theoretical investigations of the equilibrium atomic configurations and electronic properties of dimers and trimers of p-elements of IV (Pb), V (Bi) and VI (Te) groups as well as their cations and anions. The density functional theory calculations are used to obtain the equilibrium bond lengths and binding energies, vibrational frequencies, the HOMO-LUMO gaps for heavy element clusters with a strong relativistic effect. It is shown that spin-orbit coupling should be taken into consideration due to its substantial effect on energy and oscillating parameters of clusters.

There was a misprint in the third author’s name. It should read Yangyang Ju instead of Yu Yang yang.