Comparative study of holographic recording in cholesteric and nematic azo-containing side-chain polymers

For the first time a comparative study of holographic recording in planarly oriented films of nematic and cholesteric azobenzene-containing polymers was performed. The influence of temperature and light intensity on the values of diffraction efficiencies of holographic gratings was investigated. The kinetics of grating relaxation at different temperatures was studied. It was shown that the helical supramolecular structure of cholesteric copolymer causes a significant decrease of the diffraction efficiency in comparison with the one observed for the nematic state of the homopolymer.     

High-frequency magnetoimpedance in nanocomposites

The transmission of millimeter-range electromagnetic waves (30–50 GHz) through a magnetic nanocomposite thin film exhibiting tunnel magnetoresistance (TMR) is calculated. The relative change of transmission coefficient in an applied magnetic field due to the magnetorefractive effect is approximately linear with TMR and strongly depends on nanocomposite resistivity and film thickness. The obtained results are in a good agreement with experiment.     

On the possibility of terahertz wave generation upon dense gas optical breakdown

The possibility of applying the physical principles underlying the operation of a solid-state terahertz oscillator to plasma gas-discharge media is analyzed. A new method of electromagnetic wave generation in the terahertz frequency range is proposed. It is based on the excitation of plasma-oscillation current by a static electric field in a laser spark produced by an axicon lens, followed by the radiation of an electromagnetic pulse through the Cherenkov mechanism.     

Crystallographic report: Crystal structure of 1‐bromo‐1′‐[(2S)‐N‐(1‐hydroxy‐3‐methylbutane‐2‐yl)]‐ferroceneamide

For the unsymmetrical title compound, 1‐bromo‐1′‐[(2S)‐N‐(1‐hydroxy‐3‐methylbutane‐2‐yl)]‐ferroceneamide, two independent molecules were found in the asymmetric unit. Copyright © 2003 John Wiley & Sons, Ltd.     

Bisindoles 34. Preparation and reactions of dehydrazides of the benzo[e]pyrrolo[3,8-g]-indole and indolo[4,5-e]indole series

Summary 2, 9 -Di (carbohydrazide)-1 H, IOH-benzo[elpyrrolo[3, 2-g]indole and 2, 9-di (carbohydrazide)-3H, 8H-indolo[4, 5-e]indole have been prepared. Nitrosation of the dihydrazides has been effected. The aryl azides do not undergo the curtius rearrangment.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1048-1051, August, 1994.Communication 33, see [1].     

Condensation of Ketones in the Presence of Titanium Alkoxides

itanium alkoxides promote successful condensation of aromatic and aliphatic ketones provided that the liberated alcohol is selectively removed from the reaction mixture.