Effect of laser erosion on the element concentration in the surface layer of a solid

SEM data (obtained under a RÉMMA 102 microscope configured with an energy-dispersive analyzer) demonstrating the effect of surface erosion due to focused laser radiation on the elemental composition of the surface (eroded) layer are presented.     

Polarization insensitive linear intensity modulation in a Sagnac fiber-optic loop with an electro-optic cell and optoelectronic feedback

We present a modulation scheme consisting of a fiber-optic Sagnac interferometer, which has an electro-optic modulator (Pockels cell) in the loop of the interferometer. In order to diminish the nonlinearity of the Sagnac interferometer transmittance function, we monitor a very small part of the output light intensity by means of a photodiode and then amplify this signal by a constant factor ξ. This amplified signal is added to the electrical modulating signal that is being applied to the electro-optical modulator. The consequence of introducing this feedback loop is that by properly choosing the amplifying factor ξ, we can increase the linearity of the modulation. The device is insensitive to the polarization state of the input light, so it should be used for intensity modulation of nonpolarized light with up to 100% modulation depth. The theoretical and experimental examination of the device is presented.     

Investigation of nitrogen-containing heterocyclic free radicals

Dimers of 4(5)-phenyl-5(4)-β-naphthyl-2-phenyl-substituted imidazolyl radicals were synthesized in order to study the effect of a β-naphthyl group on the stability of triaryl-imidazolyl radicals, and the rate constants and energies of activation for dissociation of the dimers were determined. The presence of a β-naphthyl group in the bistriarylimid-azolyl molecule facilitates its dissociation into radicals as compared with bistriphenyl-imidazolyl.     

Chemical investigation of biomass of a culture of ginseng cells III. Polysaccharides of a callus culture of ginseng

A water-soluble polysaccharide fraction has been isolated from a callus culture of ginseng with a yield of 16–20%. It has been shown that it included starch a and acidic polysaccharides — arabinogalactans and a xyloglucan.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, USSR Academy of Sciences, Vladivostok, All-Union Scientific Research Institute of Biochemical Machinery Design, USSR Ministry of the Medical Industry, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 771–772, November–December, 1989.     

A new method for the preparation of the organic superconductor,bis(ethylenedithio)tetrathiofulvalene triiodide,β H-(ET)2I3 with critical temperature 7 K

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1690–1691, July, 1990.