5-Oxohexahydroquinolines,condensed analogs of 1,4-dihydropyridines. Preparation and properties

The optimum conditions for the preparation of 5-oxohexahydroquinolines have been established, and a probable reaction mechanism for their formation is proposed. Some reactions of these compounds have been examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 511–514, April, 1990.     

Investigation of a compressible turbulent boundary layer and a region of separation at M=5 by a laser Doppler anemometer

Results are cited of an experimental investigation of the structure of a compressible turbulent boundary layer on a thermally insulated cylinder placed longitudinally in the flow. The experiments were conducted at M=5 and Re_x10⁷. In order to establish a longitudinal positive pressure gradient and a region of separation at the end of the cylinder, a tailpiece in the shape of an axisymmetric isentropic compression surface, or conical flaps with various half angles, were mounted. Profiles of the longitudinal velocity component were measured using p_o' and t_o probes, and also using a laser Doppler anemometer (LDA) with a Fabry-Perot interferometer. In the absence of a longitudinal pressure gradient the velocity profiles measured by the different methods were in satisfactory agreement among themselves and with the results of calculations. In the presence of a longitudinal positive pressure gradient, the velocity profiles become less filled and the static pressure, calculated according to the results of measurements of the velocity with the aid of the LDA and the pressure p_o', varied across the thickness of the boundary layer. In the separated region, the recirculating velocity of the flow was measured with the aid of the LDA.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 175–178, March–April, 1976.     

Measurements of the velocity field of a hypersonic flow by a laser Doppler velocimeter

An experimental apparatus is described for measuring the local velocities of gas flows in the range from 100 to 10,000 m/sec by means of the Doppler effect. The results of investigations of a free flow and of the same flow over a sphere in a hypersonic wind tunnel at M = 5 are cited and are compared with measurements of velocity using temperature and pressure probes and with theoretical calculations. The behavior of light scattering-particles in the flow is also investigated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 69–73, July–August, 1974.     

Effect of amino acids on corrosion of copper and steel in acid medium

Efficiency of four amino acids (glycine, threonine, phenylalanine, and glutamic acid) in inhibition of corrosion of M3 copper and St.3 low-carbon steel in a 0.5 M HCl solution was evaluated.     

Investigation of the mechanism of the recyclization of furans to thiophenes and selenophenes under acid-catalysis conditions. 3. Investigation of the recyclization of homologs and functional derivatives of furan. Quantum-chemical calculations of the objects of the recyclization

The kinetics of the conversion of di-, tri-, and tetraalkylfurans to the corresponding thiophenes were investigated. A correlation between the reactivities and structures of the investigated furans was established. Quantum-chemical calculations of the objects of the recyclization were made. The calculated and experimental data on the reactivities of the investigated compounds were compared. The most likely pathway of the protonation of furans in their recyclization was determined on the basis of calculations of the total energies of the protonated forms.For Communication 2 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1614–1620, December, 1993.     

Galois subrings of simple rings

Suppose R is a finite direct sum of simple associative rings and G is a finite group of auto-morphisms of the ring R. It is shown that if there is no additive ¦G¦-torsion in R, then the subring of elements of R that are fixed under G is a finite direct sum of simple rings.