Resonance excitation of intense acoustic beams in crystals of different syngonies

The resonance excitation of an intense elastic wave in a crystal, arising under conditions of the nonspecular reflection of an incident pump wave is described for a crystal geometry close to a cut that allows the existence of a bulk eigenwave satisfying the free boundary condition. It is shown that choosing a crystal surface parallel to the plane of symmetry optimizes reflection resonance due to the coincidence of the excited wave’s intensity maximum and the reflected (parasite) wave’s intensity minimum in the same geometry of reflection. Parameters of resonance are given for a number of crystals with monoclinic, orthorhombic, and hexagonal syngonies.     

Hydraulic modeling of the flow in the delta of the River Neva and in the eastern part of the Gulf of Finland

In connection with the construction of Leningrad's flood defenses the flow in the mouth of River Neva has been investigated on hydraulic models of different scales both unpressurized (see, for example, [1, 2]) and pressurized (see, for example, [3]). Since the results of these investigations are being intensively debated in connection with the discussion of the effect of defensive structures on the ecology of the Leningrad region, it is important to analyze the scientific basis for the hydraulic modeling of such flows.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 57–65, September–October, 1990.     

Onset of convection in a horizontal fluid layer in the presence of density inversion under given heat fluxes at its boundaries

The onset of convection in a horizontal fluid layer in the presence of density inversion is studied under given heat fluxes at the layer boundaries. The stability diagram is obtained and the nature of disturbances is studied in the linear approximation. Depending on the density maximum position within the layer the instability may be both long-wave and cellular in nature.     

The use of triethanolamine ammonium salts as catalysts for the addition of carbon dioxide to epoxides

Russian Chemical Bulletin - Ammonium derivatives of triethanolamine have been effectively used as catalysts for the addition of CO2 to epoxides. The iodine additive was found to exert a positive...     

Specific features of statistical characteristics of photon trajectories in a strongly scattering medium near an object surface

Results of a detailed study of statistical characteristics of photon trajectories in a strongly scattering medium near an object surface are presented. The properties found in the study may be useful for developing an algorithm of reconstruction in real time for the optical tomography of strongly scattering (biological) object.     

Asymmetric hydrogenation of 3-methylbenz[b][1,4]oxazin-2-ones catalyzed by iridium complexes with phosphite-type ligands

Russian Chemical Bulletin - The chiral amidophosphite ligand in the iridium-catalyzed hydrogenation of 3-methylbenz[b][1,4]oxazin-2-ones in ethanol provides higher conversion and enantioselectivity...     

Stability of the Interface of a Liquid-Suspension System under High-Frequency Nonlinearly Polarized Vibration

The stability of the state of a two-layer system consisting of a homogeneous liquid and a solid particle suspension in the same liquid with a plane interface between them is investigated. The system performs both horizontal and vertical high-frequency vibration with an arbitrary phase shift. It is shown that a mean flow develops under the simultaneous action of both horizontal and vertical vibration; quantitative flow stability characteristics are determined numerically using the differential sweep method. It is shown that a traveling wave relief exists on the liquid-suspension interface. Transverse oscillations in phase with longitudinal oscillations destabilize the entire system. The presence of an oscillation phase shift can lead to an increase in the stability limit; the direction of motion of the wave relief can differ depending on the value of the phase shift. Instability of the system in the presence of strictly vertical vibration is observed, the crisis being associated with longwave monotonic perturbations.__________Translated from Izvestiya Rossiiskoi Academii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, 2005, pp. 3–13.Original Russian Text Copyright © 2005 by Lobov, Lyubimov, and Lyubimova.     

System of equations for describing dynamical problems associated with the mechanics of lung parenchyma

In [1], which is an expanded version of the paper [2], the equations of conservation of mass and momentum are shown to be valid for dynamical problems of lung parenchyma. This system of equations is now closed by means of the heat flux equation. As in [1, 2], the heat flux equation is obtained on the basis of the methods of the mechanics of heterogeneous media [3] and anatomical data on the structure of lung parenchyma.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 21–29, May–June, 1988.     

Asymmetric hydrogenation with the use of chiral carborane amidophosphite derivatives in supercritical carbon dioxide and CH2Cl2

New chiral carborane-containing amidophosphites containing the BINOL fragment (BINOL stands for 2,2′-dihydroxy-1,1′-binaphthyl) have been synthesized. The study of efficiency of these compounds as ligands in the Rh-catalyzed asymmetric hydrogenation of enamides in supercritical carbon dioxide (scCO₂) and CH₂Cl₂ showed that enantioselectivity of the process is considerably higher in scCO₂.     

Carborane-derived diphosphites: New ligands for Pd-catalyzed allylic amination

A series of chiral diphosphite ligands bearing sterically congested carborane fragments have been prepared and applied in the Pd-catalyzed allylic amination of 1,3-diphenylallyl acetate with pyrrolidine and di-n-propylamine (up to 83% ee).