On isometric immersions with flat normal connection of the hyperbolic space L n into Euclidean space E n+m

We prove that the hyperbolic space L ⁿ cannot be immersed in an Euclidean space E ^n+m with a flat normal connection provided the module of the mean curvature vector is bounded.     

Macroscopic Dimension of 3-Manifolds

In this paper we give the answer to the Gromov's question about the macroscopic dimension of universal coverings of closed manifolds in dimension 3. We prove that the macroscopic dimension of a universal covering of a closed Riemannian 3-manifold cannot be equal to 2.     

Study of vibrational relaxation of CO2 molecules at the surface of a BaF2 crystal by the phase method

The phase method is used to experimentally study vibrational relaxation of CO₂ molecules found at the vibrational energy level 00°1 when they collide with the surface of a BaF₂ crystal. The probability of heterogeneous deactivation is determined for the temperature T=300°K in a calculation for one collision with an active center of the crystal of the surface _s=0.46±0.04 and with a surface layer of adsorbed molecules _g=0.06±0.01. The pressure of the gas in the working cell was varied in the range from 1 to 15 torr.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 49–53, July, 1986.     

New Sensory Materials Based on Chalcogenide Glasses Containing Zinc,Cadmium, and Manganese Sulfides

New chalcogenide glasses of the system 0.5AgI-(0.5 - x)Sb₂S_3-x MS containing cadmium, man- ganese, and zinc sulfides were obtained. The high purity of these materials and their glassy state were proved by X-ray analysis and X-ray fluorescence energy-dispersive spectroscopy. The impedance of the glasses obtained was measured within a wide range of frequencies, and the dependences of the conductivity on the composition of glasses were studied. New potentiometric sensors based the new glasses were developed, and an electrochemical experiment was carried out.     

XANES and XPS studies of processes initiated by high-vacuum annealing in SnO x /MWCNT composite layers

The initial and thermally treated composites based on SnO _x /MWCNT have been studied by the XANES and XPS methods using the equipment of the BESSY II Russian-German beamline of synchrotron radiation and by the AES and HRTEM methods. The characteristic mechanisms of chemical and structural transformations in the SnO _x phase have been determined depending on the vacuum annealing temperature. It has been found that the basic process in the metal-oxide component at annealing temperatures not exceeding 500°C is the tin monoxide SnO disproportionation reaction with the formation of the dioxide SnO₂ phase and metallic tin. An increase in the annealing temperature to 800°C results in the activation of carbothermal reduction of metallic tin in contact areas of oxide clusters and MWCNT, as well as in the formation of nanocrystalline structures in the metal-oxide component of composite.     

Study of K^ - \to \pi ^0 e^ - \overline \nu _e \gamma decay with ISTRA+ setup

Results of study of the $K^ - \to \pi ^0 e^ - \overline \nu \gamma $ decay at the ISTRA+ setup are presented. We observed 4476 events of this decay. The branching ratio is found to be $R = \frac{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e \gamma )}}{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e )}}$ = (1.81±0.03(stat.)±0.07(syst.)) × 10^?2 for E*_γ > 10 MeV and θ*_eγ > 10°. For comparison with the previous experiment the branching ratio with cuts E*_γ > 10 MeV, 0.6 < cos θ*_eγ < 0.9 is calculated: R = $\frac{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e \gamma )}}{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e )}}$ = (0.47±0.02(stat.) ± 0.03(syst.)) × 10^?2. For the cuts E*_γ > 30 MeV and θ*_eγ > 20°, used in most theoretical papers, Br = (3.06 ± 0.09(stat.) ± 0.14(syst.)) × 10^?4. For the asymmetry we get A _ξ = ?0.015 ± 0.021. At present it is the best estimate of this asymmetry.     

Fractal communication system

Complex electromagnetic situation and the need in protecting information from unauthorized access require new engineering solutions in the development of communication system. One of such approaches is associated with fractal communication systems (FCSs) employing antijamming waveforms with fractal spectra as information carriers. Basic concepts of an FCS are considered and the results of its practical implementation for computer communication via an aerial or a coaxial cable are discussed.     

p-V-T parameters of propylencarbonate and cis-,trans-decahydronaphthalene in temperature and pressure ranges of 20–50°C and 1–1000 bar

The condensability of propylencarbonate and cis-,trans-decalin (40: 60 wt %) were measured using the liquid weighting method in the temperature and pressure ranges of 20–50°C and 1–1000 bar, respectively. The Tait equation coefficients C and B for this temperature interval were calculated. Taking pro-pylencarbonate as an example, it was demonstrated that equation 1/β _T = 0.9759 × (1000V ₀/ΔV _{1 kbar}) — 4386 proposed earlier for liquids allows us to predict C and B coefficients with good precision.     

Formation of por-Si/SnOx nanocomposite by high-power ion beams of nanosecond duration

Layers of por-Si/SnO _x nanocomposite formed by high-power ion beam irradiation with nanosecond duration have been studied. The results of structural and elemental analyses of these layers are presented. The high sensitivity of this nanocomposite to low NO₂ concentrations at room temperature has been revealed.     

Spectroscopic ellipsometry study of porous silicon-tin oxide nanocomposite layers

The layer-by-layer distribution of components in a porous silicon-tin oxide nanocomposite produced by the following three methods is studied by spectroscopic ellipsometry: chemical vapor deposition, atomic layer deposition, and magnetron sputtering. It is shown that, in the nanocomposites fabricated by these methods, SnO _x penetrates to a depth more than 400 nm and is nonuniformly distributed over the porous layer thickness. The nanocomposite prepared by magnetron sputtering followed by heat treatment has the maximum penetration depth and the maximum uniformity of layer-by-layer SnO _x distribution.