Dynamic reflection holograms in CdF2 crystals with bistable centers

The diffraction efficiency and the recording and relaxation times of dynamic reflection holograms, recorded in CdF₂ crystals with bistable centers are studied experimentally in the temperature range 20–100°C. In the model experiments which measured the quality of the wave reflected from the hologram, the dynamic wavefront distortions are demonstrated to be efficiently compensated using a holographic corrector based on these crystals. CdF₂ crystals with bistable centers are likely to be useful in solving problems of correction of laser light wavefront and image correction in observation telescopes with nonideal primary mirrors.     

Algebraic methods in quantum mechanics: from molecules to polymers

We present a brief review of algebraic techniques developed and applied in molecular spectroscopy in the last five years. We also outline perspectives for new applications of the Lie algebraic method in the first decade of the new century. Received 21 November 2001     

The cardinality of manifold atlases

It is shown that any finite dimensionalC ⁰ manifold (connected and Hausdorff but otherwise unrestricted) has an atlas of cardinality not greater than that of the continuum; while if it has a Hölder continuous pseudo-Riemannian metric then there is a countable atlas.     

Some experiences in controlling contamination of environmental materials during sampling and processing for low-level actinide analysis

Selected experiences in the control of contamination and the threat it poses to the quality of analytical date are discussed in the context of the whole analytical process from collection of marine environmental samples, through handling and radiochemical separation, to the final interpretation of results. Examples include a demonstration of the contamination introduced during sediment core sectioning, contamination of sea water by a ship's pumping system, and the effect of filtration on the apparent partitioning of radionuclides between solid and liquid phases of sea water.     

Synthesis and biological activity of S-oxo-[(methylthio)-methyl]cysteinols

A convenient route was developed to synthesize S-oxo-[(methylthio)-methyl]cysteinols on a large scale from cheap l-serine as the starting material. The structures of diastereoisomers were determined by NMR, CD spectra, and X-ray diffraction analysis. All four diastereoisomers were examined for their ability to inhibit certain bacteria from growing.     

An efficient synthesis of isothiazolidines via sulfonium ylides formed by the reaction of thietanes and nitrene

An efficient synthesis of isothiazolidines in good yields is described.     

A thermodynamic description of the distribution of water in H2O-tributyl phosphate and H2O-tributyl phosphate-solvent systems

Various methods for describing the distribution of water in the H₂O-tributyl phosphate (TBP) system were considered. An equation for describing the deviations from the Henry law was proposed. A three-parameter equation for calculating the distribution of water in H₂O-TBP-solvent systems was derived. It is based on the additive solubility model and allows for the dependence of the activity coefficients on the TBP concentration. Based on the published data, the parameters of the equation for a number of systems were calculated.