Black holes in multidimensional theory with Ricci plane internal spaces

A generalization of the solution of Tangherlini [1] to the case of internal Ricci plane spaces is obtained. It is shown that a horizon exists in the (2 + d)-dimensional section only in the trivial case where the scale factors of the internal spaces are constant. The p-adic analog of the solution is considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 62–65, September, 1991.     

Synthesis of halo-substituted sym-polynitropentanes

Conclusions The fluorination, chlorination, and bromination of the 1,1,1,3,5,5,5-heptanitropentane and l,5-difluoro-1,1,3,5,5-pentanitropentane ions gave the corresponding 3-halo derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2163–2164, September, 1982.     

Triterpene glycosides of Astragalus and their genins XLII. Cycloartanes of Astragalus tragacantha

Another six components ofAstragalus tragacantha Habl. have been identified on the basis of spectral characteristics and chemical transformations. We have previously described cyclocanthagenin and its 3-0--D-xylopyranoside — cyclocanthoside A — as products of the acid hydrolysis of cyclocanthoside D. Cyclocanthosides B, C, E, and G are here described for the first time and are (24S)-cycloartane-3,6,16,24,25-pentol 3-O-(4-O-acetyl--D-xylopyranoside) 6-O--D-glucopyranoside, (24S)-cycloartane-3,6,16,24,25-pentol 6-O-(6-O-acetyl--D-glucopyranoside) 3-O--D-xylopyranoside, (24S)-cycloartane-3,6, 16,24,25-pentol 6-O--D-glucopyranoside, and (24S)-cycloartane-3, 6, 16, 24, 25-pentol 6-O--D-glucopyranoside 3-O-[O--D-glucopyranosyl-(12)--D-xylopyranoside], respectively.Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Institute of Ecological Genetics, Moldavian Academy of Sciences, Kishenev. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 360–367, May–August, 1992.     

Structural characteristics of fluoronitro derivatives of pentane

Division of the Institute of Chemical Physics, Academy of Sciences of the USSR. Translated from Zhurnal Struckturnoi Khimii, Vol. 31, No. 1, pp. 126–131, January–February, 1990.     

Mixed polynitroorthocarbonates

The reaction of-nitro- and-fluoro--nitrodichloroformals with -nitroalcohols in the presence of ferric chloride gave mixed 22-polynitroorthocarbonates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 198–200, January, 1991.     

Reaction of organosilicon hydrides with solid surfaces: an example of surface-catalyzed self-assembly

The solution-phase reactions of octadecylsilane (C(18)H(37)SiH(3)) with 10 high surface area metal oxides (groups II-VIII) were investigated. C(18)H(37)SiH(3) reacted with most metal oxides at room temperature and produced supported monolayers (self-assembled monolayers, SAMs) with a high grafting density of C(18), approximately 4.5-5 groups/nm(2). According to the FTIR and (29)Si NMR spectra, molecules in the SAMs demonstrated "horizontal" cross-linking (Si-O-Si and Si-OH.HO-Si bonds) and little or no "vertical" bonds with the metal oxide forming an amorphous, yet ordered film. Also, approximately 3 mol of H(2) was formed per each mole of grafted C(18), indicating complete hydrolysis of C(18)H(37)SiH(3) during the reaction. On the basis of the activity of different metal oxides, we concluded that the hydrolysis of C(18)H(37)SiH(3), the key step in the reaction mechanism, is catalyzed by water adsorbed on acidic and basic centers (Lewis and Br?nsted) of the surface of metal oxide. Metal oxides and solids with weak acidic and basic properties, like silica, carbon, and organic polymers, do not react with C(18)H(37)SiH(3). Increasing the temperature of the reaction or doping neutral surfaces with acids or bases greatly increases their activity in the reaction with RSiH(3).