Addition-curable type liquid silicone rubbers based on phenyl-containing organopolysiloxanes with terminal vinyl groups

Russian Chemical Bulletin - A series of organosilicon rubbers of the addition-curable type containing dimethyland methylphenylsiloxy, or diphenylsiloxy units with terminal vinyl groups were...     

29Si NMR spectra of methylphenylcyclotri-and -tetrasilazanes

²⁹Si NMR spectra of various methylphenyl-substituted cyclotri- and -tetrasilazanes, composed of different combinations of the units d = Me₂SiNH, d^ph = MePhSiNH and d = Ph₂SiNH, have been investigated. For most of the compounds having more than one asymmetric centre, the spectra of both the individual isomers and their mixtures have been studied, and the signals of the individual isomers have been assigned. The effect of a different arrangement of phenyl groups in the rings, and the influence of the stereochemistry of the isomers on the ²⁹Si chemical shifts in cyclotri- and -tetrasilazanes have been studied. The ²⁹Si chemical shifts in cyclotrisilazanes are additive and can be represented as the sum of increments corresponding to the number and positions of the phenyl groups in the rings. In these compounds, the spatial structure of the isomers does not exert any noticeable effect on the spectra. On the contrary, chemical shifts are not simply additive in cyclotetrasilazanes: a pronounced stereochemical dependence is apparent.     

Hydration of sodium and copper forms of carboxyl-containing ion exchange fibers

The state of water in VION KN-1 carboxyl-containing ion exchange fibers was estimated by the thermogravimetric analysis and isopiestic methods. The presence of water with different degrees of binding was confirmed, and the hydrartion numbers of fiber corresponding to each stage of water removal were determined. The Gibbs free energies of hydration of sodium and copper forms of fiber were calculated.     

Buckling of a bar on an elastic base

Novosibirsk. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 5, pp. 106–112, September–October, 1994.     

Elimination of Diurnal,Annual, and Solar Variations in the Matrix Observations of the URAGAN Muon Hodoscope

Physics of Atomic Nuclei - A method for elimination of periodical diurnal, annual, and 27-day and 11-year solar variations in the matrix observations of the URAGAN muon hodoscope was developed. The...     

Shear strain effects on the theoretical strength of an atomic lattice

A four-atomic unit cell corresponding to a close-packed layer of atoms is considered. It is shown that with occurrence of a shear the system prematurely loses stability. It is concluded that in Novozhilov-type integral criteria for brittle strength, it is reasonable to take into account shear strains. Lavrent’ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 4, pp. 208–213, July–August, 1999.