Overequilibrium heating of the surface of a heat-shield tile in a subsonic jet of dissociated air

The results of measuring and numerically calculating the surface temperature distributions of heat-shield tiles with uniform and nonuniform catalytic coatings exposed to subsonic dissociated-air flows in an induction plasmotron are presented. The measurements are consistent with the calculated surface temperature profiles obtained from a numerical solution of the Navier-Stokes equations for a chemical-nonequilibrium flow of dissociated nitrogen. The results are compared with the data of a space shuttle flight experiment on the effect of a discontinuity of heat shield catalyticity on the overequilibrium surface temperature jump.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 144–150, May–June, 1991.     

Bimodal dependence of light scattering/fluctuations on the concentration of aqueous solutions

Two concentration ranges (from 10^?5 to 10^?9 and from 10^?13 to 10^?18 M) corresponding to enhanced fluctuations of Rayleigh and Raman scattering of second-harmonic (527 nm) pulses of YVO₄:Nd³⁺ laser are found for aqueous solutions of antioxidant potassium phenosan. A correlation is revealed between the rise in elastic Rayleigh scattering intensity and its fluctuations and the shift of the center of OH Raman band of water toward the ice component characteristic frequency (3200 cm^?1). The development of phase-equilibrium instabilities is analyzed based on the model of fluctuations of the number of hydrogen bonds on the assumption of formation/destruction of ordered hydration layer of phenosan molecules in water.     

Nonlinear induced reflection of light waves in semiconductors

A scheme of nonlinear optical four-wave mixing of two counterpropagating laser beams on the surface of a semiconductor is proposed and analyzed. It is shown that the density modulation of the electron-hole plasma current carriers in the light-induced grating manifests itself in the probe beam depolarization signal after the reflection from the surface, which is sensitive to the state of the surface and presence of complex molecules on it.     

Eleuthesides and their analogs: XI. Final stage of the synthesis of sarcodictyin A analog with 14-methylcyclohex-12-ene ring A

Proceeding from derivatives of levoglucosenone and piperilene Diels–Alder adduct a total chemical synthesis was completed of sarcodictyin A analog possessing a 14-methylcyclohex-12-ene ring А. A practical version was developed of N(τ)-methylation of urocanic acid.