Remote detection of HF molecules in open atmosphere with the use of tunable diode lasers

This paper sets out to present the results of a study of the feasibility of building a prototype device for prompt (on-line mode) remote measurements of HF trace quantities in atmosphere (with the optical length of up to 100 m, and a cat’s eye as a reflector) making use of near-infrared range diode lasers (DLs). The gas analyzer consisted of DLs operating at λ=1.28 μ, a telescopic system and a retro-reflector. The remotely measured HF sensitivity in atmosphere was better than 10 ppb.     

Quasi-nanowires from fluorescent semiconductor nanocrystals on the surface of oriented DNA molecules

Ordered structures in the form of quasi-nanowires were obtained from CdSe/ZnS fluorescent semiconductor nanoparticles of spherical (quantum dots) or rodlike (quantum rods) form by their electrostatic deposition on DNA molecules with subsequent stretching of the molecules on a solid substrate. Positively charged nanoparticles were fixed along the negatively charged backbones of DNA molecules by electrostatic interactions in an aqueous solution of a mixture of DNA with quantum particles at different stoichiometric ratios. Strands of single DNA molecules with quantum particles fixed along them were immobilized and stretched on hydrophobic surfaces using the molecular combing technique. It is shown that, by varying the nanoparticle charge and the stoichiometry of complexes of DNA with particles, it is possible to create fluorescent structures with predetermined morphology and properties.     

Steady streaming around a spherical drop displaced from the velocity antinode in an acoustic levitation field

The steady (acoustic) streaming associated with a sphericaldrop displaced from the velocity antinode of a standing waveis studied. The ratio of the particle size to the acoustic wavelengthis treated as small but non-zero, and the solution is developedin the form of a two-term expansion in terms of the correspondingsmallness parameter. The drop viscosity is assumed to be muchhigher than that of the surrounding fluid, which is the casefor a drop in a gas medium. There are essentially three distinctregions where the steady streaming flow is analysed: insidethe drop (internal circulation), in the Stokes shear-wave layerat the surface on the gas side, and the gas outside the Stokeslayer (the outer streaming region). Solutions for the internalcirculation and the outer streaming are obtained in the limitof small Reynolds number. Despite the gas-to-liquid viscosity ratio being small, the outerstreaming may be dramatically affected by the fact that thesphere is liquid as opposed to solid. The parameter that measuresthe effect of liquidity is essentially the viscosity ratio dividedby the relative (to the particle size) thickness of the Stokeslayer. The case of a solid sphere is recovered by letting thisparameter go to zero.     

Separation of the lignocellulose of nonwoody plants into its main components and study of their properties

Hemicellulose fractions possessing biological activity have been isolated from the lignocellulose of nonwoody plants (kenaf tow, cotton stems) by alkaline extraction.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 364–367, May–June, 1998.     

Accelerator-driven sub-critical reactor system (ADS) for nuclear energy generation

In this talk we present an overview of accelerator-driven sub-critical reactor systems (ADS), and bring out their attractive features for the elimination of troublesome long-lived components of the spent fuel, as well as for nuclear energy generation utilizing thorium as fuel. In India, there is an interest in the programmes of development of high-energy and high-current accelerators due to the potential of ADS in utilizing the vast resources of thorium in the country for nuclear power generation. The accelerator related activities planned in this direction will be outlined.     

Synthesis and spectral properties of hexafluoroaurates

It is established that krypton difluoride (KrF₂) interacts with metallic gold in anhydrous hydrogen fluoride (HF) in the presence of alkaline and alkaline-earth metal fluorides with the formation of complex hexafluoroaurates with the general formula M^IAu^VF₆ (M^I = Li, Na, K, Rb, Cs) and bis-hexafluoroaurates M^II(Au^VF₆)₂ (M^II = Mg, Ca, Sr, Ba). As a result of the subsequent interaction of bis-hexafluoroaurates with krypton difluoride, new coordination compounds with the composition M^II(Au^VF₆)₂ · nKrF₂ (M^II = Ca, Sr, Ba; n = 0–4) were synthesized. The Raman spectra were studied and a comparative analysis of the Raman spectra of the obtained compounds was performed. The possible variants of the structural transformation of the AuF ₆ ^? anions in compounds and the position and character of the chemical bond of the “guest” (KrF₂) in these compounds are discussed.     

Reaction of phenols with methylcycloalkenes in the presence of KU-23 catalyst

Cycloalkylation of phenol, p-methylphenol, and p-hexylphenol with 1-methylcyclopentene and 1- and 3-methylcyclohexenes in the presence of KU-23 catalyst in the H form was studied.     

Spectral and Spatial Characteristics of the Electromagnetic Modes in a Tunable Optical Microcavity Cell for Studying Hybrid Light–Matter States

JETP Letters - Studies of resonance interaction between matter and localized electromagnetic field in a cavity have recently attracted much interest because they offer the possibility of...