Relative viscosity and the solvation number in solutions

It has been shown that part of the free volume of a solvent attaching to the solvation shell must be excluded from the total free volume in the Bachinskii equation. This determines the increase of viscosities of solutions with positive solvation. An equation has been obtained for the inverse relative viscosity of solutions ₀/ = 1-zN₂/(1-N₂), where no and are the dynamic viscosities respectively of the solvent and the solution; z is the solvation number, N₂ is the mole fraction of dissolved material. A method is proposed for determining the solvation number (hydration) from solution viscosity data. Solvation numbers obtained by this method are in good agreement with values of z obtained from the literature and determined by other methods.Translated from Teoreticheskaya i Experimental'naya Khimiya, Vol. 21, No. 5, pp. 627–631, September–October, 1985.The author wish to express their gratitude to professors Yu. Ya. Fialkov and M. A. kvadrigin for fruitful discussions of the result of the current work.     

Synthesis of methyl 2,6-dideoxy-β-D-arabino-, 3,6-dideoxy-β-D-ribo-, and 4,6-dideoxy-β-D-xylo-hexopyranosides

A convenient method is proposed for the synthesis of methyl 1,6-dideoxy-β-D-arabino-, 3,6-dideoxy-β-D-ribo-, and 4,6,dideoxy-β-D-xylo-hexopyranosides by the partial deoxygenation of methyl β-D-quinovopyranoside followed by liquid chromatography of the dideoxysugars. Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 741–743, November–December, 1991.     

Variation of physicochemical properties in the aggregates of structual isomers

The regions of variation of density, enthalpy of formation, and detonation velocity of all of the formally possible structual isomers were determined for several molecular formulas of C,H,N,O-containing explosives. The histograms of the distribution of the structual isomers over these parameters were constructed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 859–862, May, 1995.The authors are grateful to Mrs. I. D. Solodukhina for the design of the graphical material.The work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 94-03-09323).     

CuBr-Ne-HBr laser with a high repetition frequency of the lasing pulses at a reduced energy deposition in the discharge

Experimental and computer studies of the CuBr laser with periodic-pulse pumping are performed with and without addition of HBr. The analysis based on the numerical simulation reveals how additions improve the lasing characteristics of this laser at both typical (10 to 20 kHz) and higher (up to 100 kHz) excitation pulse repetition frequencies during the operation with a low energy deposition in the discharge. This allows the lasing pulse repetition frequency to be increased in the experiment to 750 kHz, which does not seem to be a limit as yet.     

Computer generation and theoretical study of alicyclic caged structures without small-size cycles

Computer design was concocted for a series of caged alicyclic structures without small cycles. With the help of molecular-mechanical calculations, the enthalpies of formation and the strain energies were determined for the corresponding compounds. The possibility of tile existence of highly strained frameworks without small cycles was analyzed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2430–2437, October, 1996.     

Simulation of mesospheric-composition disturbances under the action of high-altitude discharges (sprites)

Recent measurements show that a mesospheric electric discharge (sprite) can provoke disturbances in the chemical composition of the mesosphere. In this paper, we propose a plasmachemical system of equations which allows one to describe the complex relationship among chemical components during the discharge. Disturbances of the mesospheric ion composition are analyzed under the night-time and daytime conditions at an altitude of 75 km, which is typical of the sprite initiation and at an altitude of 85 km where the diffuse region of discharge is usually observed. The most probable scenarios of development of the electric-field and electron-temperature disturbances, which are characteristic of the diffusive and streamer regions of the sprite, are simulated. The value and characteristic time of disturbances of the main ion components (O₂ ⁺, NO⁺, H₃O⁺, H₅O₂ ⁺, and N₂ ⁺) are evaluated. The obtained values of the electron-density disturbances are in agreement with experimental and theoretical data. It was established that the sprite series, which are recorded over the vast stratified regions of mesoscale convection systems, can lead to generation of comparatively long-lived disturbances in the ion composition of mesospheric plasma.     

Influence of convective cooling of the external surface of a plane-parallel layer on the temperature distribution on a layer–base tribosystem

An analytic solution of the boundary-value problem of heat conduction for a tribosystem that consists of a plane-parallel layer sliding over the surface of a semiinfinite base with a constant velocity is obtained. For the materials of an aluminum–steel friction pair, we investigate the evolution of temperature and its distribution in the layer and base along the normal to the friction surface.     

Study of a Pulsed Air Flow in a Large Vacuum Chamber by Means of a Commercial Ionization Gauge

Technical Physics - A method for creating a pressure gradient by pulsed injection of air into a large vacuum chamber for laboratory simulation of plasma phenomena in a vertically nonuniform...