Diffraction of a two-shock configuration by a convex cylindrical surface

The subject of this work is numerical investigation into the diffraction of a shock-wave configuration by a convex cylindrical surface. The diffraction is a stage of interaction of a shock wave with a two-dimensional body. It is preceded by the stage of shock wave reflection from the front surface of the body, the back surface of which has a convex cylindrical shape. The two-or three-shock configuration formed on the front surface diffracts by the back cylindrical surface. The emphasis is on studying the diffraction of the two-shock wave configuration with the diffraction angle varying continuously. The object under study a wedge with an inclined front surface and convex cylindrical back surface. The results of numerical investigation are obtained by integrating the Euler equations. Flow features associated with the simultaneous diffraction of the incident and reflected shock waves are revealed. The evolution of the gasdynamic system (stagnation wave + TU layer) arising inside the diffraction area is studied. Breakaway and vorticity initiation are considered. It is shown that the positions of the line of separation and TU layer change in the course of diffraction. They merge together at the stage of steady flow. Comparison is made between the flow formed upon diffraction of the two-shock configuration by the cylindrical surface and the flow generated upon diffraction by horizontal and vertical surfaces.     

Natural antioxidants. Furanoeremophilanes from Cacalia roots

Sesquiterpene compounds of the furanoeremophilane series have been isolated from extracts of the roots ofCacalia sp. growing in the Soviet Far East. The presence of antioxidant and antiradical activities in two representatives of the series has been established. Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 643–646, September–October, 1989.     

Production of condensed phosphate by plasma chemical treatment of phosphate raw material

Thermodynamic calculations and experimental studies have demonstrated that dissociation of natural phosphates in a low-temperature plasma involves partial calcium oxide evaporation. As a result, upon cooling gaseous products of the dissociated phosphate raw material, compounds containing condensed calcium phosphate are formed. The composition and properties of condensed calcium phosphates, which can be used as fertilizers, are discussed.     

Cross-couplings of alkyl halides with heteroaromatic halides, in water at room temperature

Zn-mediated, Pd-catalyzed cross-coupling reactions between heteroaromatic and alkyl halides can be done at room temperature in pure water using a commercially available Pd catalyst and PTS, a nanomicelle-forming amphiphile. Notably, zinc metal inserts selectively into a carbon sp³-halide bond, while palladium adds oxidatively to a carbon sp²-bond.     

Mass spectrometry of stereoisomeric 3-hydroxy-4-piperidones

The existence of several sites of charge localization upon the mass spectrometric decomposition of stereoisomeric 3-hydroxy-4-piperidones leads to a large number of fragmentation products both with retention and destruction of the piperidine ring. Analysis of the mass spectra of the compounds studied showed that the appearance of [M — CO]⁺ ion peaks for isomers with an axial hydroxyl group may serve as a method for determining the configuration of the carbinol site of such cyclic structures.Translated from Khimiya Geterotsiklichesikh Soedinenii, No. 3, pp. 375–379, March, 1986.