Liquid crystal side chain polysiloxanes containing various proportions of non-mesogenic units

Recent studies have established that side chain polymeric liquid crystals composed of mesogenic and non-mesogenic side groups keep their liquid-crystalline properties even for a low proportion of mesogens. We show that the detailed structures of three kinds of new diluted liquid crystal polysiloxanes depend on the nature of the co-substituent as well as on the proportion of the silicon sites occupied by the mesogenic groups. Mixtures of these systems with low molar mass liquid crystals were also investigated in terms of compatibility and/or stabilization of smectic A phases.     

Development of the Bogolyubov-Mitropol'skii method of integral manifolds

A survey is presented of some results relating to the development of the Bogolyubov-Mitropol'skii method of integral manifolds.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 44, No. 1, pp. 33–46, January, 1992.     

Evaluation of peroxyoxalate chemiluminescence postcolumn detection of fluphenazine in urine and blood plasma using high performance liquid chromatography

Peroxyoxalate chemiluminescence may be used for sensitive postcolumn detection of phenothiazine analytes separated by high performance liquid chromatography with appropriate optimization of measurement conditions such as solvent, pH and oxalate ester. Detectability of fluorescent analytes by chemical excitation varies greatly, but analytes with low oxidation potentials are generally more readily detected at low levels, as demonstrated for phenothiazines, an important class of fluorescent drugs. Some improvement in detection limits is observed for fluphenazine when chemiluminescence detection is compared to conventional fluorescence detection. Because of the specificity of chemical excitation, fewer interferences from fluorescent impurities in a urine matrix are observed.     

Effect of plasma treatment of the dielectric on electroforming of a thin-film MIM system

It was found that when a thin dielectric film is exposed to the plasma of a low-voltage gas discharge, channels with elevated conductivity form in the film and these channels significantly facilitate the subsequent electroforming of the MIM system. It is concluded from the experimental data that even in the case of metallic electrodes highly conducting channels are formed in the dielectric by electronic processes occurring under the conditions of a strong electric field and not by diffusion of the electrode material.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 94–98, October, 1991.     

Mössbauer gamma echo

By applying stepwise phase modulation of recoilless gamma radiation in a coincidence experiment, constructive interference is produced in transmission geometry between the source and the absorber fields. The resulting regenerated decay signal is called a gamma echo. Here it is demonstrated that during the decay of the 14.4 keV state of⁵⁷Fe multiple echo signals can be generated.     

Weak antilocalization in a 2D electron gas with chiral splitting of the spectrum

Motivated by the recent observation of the metal-insulator transition in Si MOSFETs, a study is made of the quantum interference correction to the conductivity in the presence of the Bychkov-Rashba spin splitting. For a small splitting, a crossover from the localizing to antilocalizing regime is obtained. The antilocalization correction vanishes, however, in the limit of a large separation between the chiral branches. The relevance of the chiral splitting for the 2D electron gas in Si MOSFETs is discussed. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 2, 118–123 (25 January 1998) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Strings at nonzero temperature

String theory at nonzero temperature is reviewed. A bosonic string at nonzero temperature is studied and the calculation of its free energy in both the one-loop approximation and the case of arbitrary genus (multiloop analysis) is discussed. A string at nonzero temperature is compared with a string compacted on a one-dimensional torus. The properties of modular invariance and dual symmetry are discussed at both the one-loop and multiloop levels. The thermodynamics of superstrings, including also superstrings compactified on a torus, is also studied. Possible cosmological applications are briefly considered. It is shown that many features of string thermodynamics (in particular, the existence of the Hagedorn temperature and dual symmetry) also occur in the theory of noncritical strings.Translated from Izvestiya Vysshykh Uchebnykh Zavedenii, Fizika, No. 12, pp. 3–49, December, 1991.