Three-dimensional dynamics of a vortex array in rotating superfluid

This work studies numerically three-dimensional formation of a vortex array in a rotating cylindrical vessel. The formation process and the resulting equilibrium pattern are affected by pinning sites on the vessel’s bottom.     

Preconcentration and selective determination of traces of tin in natural waters

A combined preconcentration-photometric determination technique has been worked out for trace concentration of tin in fresh and sea waters. After refluxing the sample acidified to 1M HCl for 2 h, tin is preconcentrated by anion-exchange in the presence of thiocyanate and recovered by elution with dilute HNO₃. Tin is then generated as stannane, caught in permanganate solution, and determined spectrpphotometrically with phenylfluorone. The results are quoted on the determination of tin in several fresh and sea waters in the order of submicrogram of tin per litre. The results for tin are in good agreement with those obtained for these samples by manganese dioxide coprecipitation-hydride generation-phenylfluorone spectrophotometric method that is also newly developed.     

An improved procedure for syntheses of silyl derivatives of the cubeoctameric silicate anion

The reaction of the Si₈O₂₀^8? silicate anion with X(CH₃)₂SiCl (X?H or CH₃) has been studied to develop a cost‐effective procedure for synthesizing Si₈O₂₀[Si(CH₃)₂X]₈ in high yield. Use of hexane as solvent and adjustment of the reaction temperature to ca 20 °C were found to be effective in promoting the reaction, by which Si₈O₂₀[Si(CH₃)₂X]₈ could be produced in good yield employing 24 mol of X(CH₃)₂SiCl per mole of Si₈O₂₀^8?. It was also demonstrated that the yield of Si₈O₂₀[Si(CH₃)₂X]₈ depends on the amount of solvent, suggesting that the amount is an important factor when scaling up the reaction to produce a large quantity of Si₈O₂₀[Si(CH₃)₂X]₈. Copyright © 2003 John Wiley & Sons, Ltd.     

FLASH-INDUCED FAST CHANGE IN SURFACE POTENTIAL AND FLUIDITY OF PURPLE MEMBRANE STUDIED BY SPIN LABEL METHOD

Abstract— Flash-induced changes in surface potential and fluidity of purple membrane were studied by a spin label method. Changes in surface potential and fluidity were monitored by observing the distribution of charged and uncharged spin labels between the purple membrane and the aqueous phase.
On flash illumination, a transient hyperpolarization of the surface potential and a transient fluidization of the membrane hydrophobic region are induced. The former may probably reflect the proton movement near the purple membrane surface, while the latter may result from photo-induced conformational changes of bacteriorhodopsin.
The two events are different in time course. The relationships between the two events, and the formation and decay of the intermediates of bacteriorhodopsin in the photoreaction cycle are discussed.     

Electrochemical determination of the superoxide ion concentration from KO2 dissolved in dimethyl sulfoxide.

An electrochemical determination of the O2- concentration from KO2 in DMSO solution using steady state microelectrode voltammetry shows that the KO2/DMSO method with the combined use of a crown compound or sonication is a reliable and simple technique for introduction of O2- to the biomimitic reaction system.     

Determination of elements in lithium potassium niobate and lithium niobate containing vanadium by ICP-AES

The elements in lithium potassium niobate and lithium niobate containing vanadium (such as aluminum, lithium, niobium, potassium and vanadium) were determined by inductively coupled plasma atomic emission spectrometry after fusion of the sample with ammonium hydrogensulfate. The samples were completely decomposed and high precision results were obtained for the metallic elements. Oxygen has been determined by a helium carrier fusion thermal conductivity method using both a nickel capsule and tin as a melting flux in a graphite crucible.     

Preparation of immobilized tannins for protein adsorption

Preparation and adsorption specificity of tannins immobilized by covalent binding on water-insoluble matrices were investigated. Immobilized tannins were prepared by condensing cyanogen bromide activated tannins with aminohexyl derivatives of several kinds of matrices. The most suitable matrix for the immobilization of tannin was alkali-treated cellulose powder. The concentration of sodium hydroxide solution for alkali treatment influenced the adsorption capacity of immobilized tannin for a protein, but temperature and time for alkali treatment did not. Immobilized tannins having spacers of long chain length exhibited high adsorption capacity for a protein. Chinese gallotannin was the most favorable ligand for protein adsorption. The immobilization of tannin on aminohexyl matrices was also possible by using epichlorohydrin instead of cyanogen bromide. The maximum adsorption capacity of the immobilized tannin for a protein was about 50 mg/ml of the absorbent. Immobilized tannin adsorbed proteins specifically but did not absorb low molecular weight compounds.     

Current reversal in the thermally stimulated current spectra of polyethylene

Polyethylene thermoelectrets were prepared under static electric fields ranging from 70 to 750 kV/cm at various polarization temperatures. Thermally stimulated current (TSC) spectra were observed for those samples in the high-temperature region above room temperature. The TSC spectra of polyethylene were complex and were composed of two current peaks, of opposite polarity and dependent on the applied voltage and temperature. This result suggests that there are two trapping mechanisms which result in different charge injection modes. In addition, TSC spectra were obtained on polyethylenes of various morphologies to examine the relationship between the mechanical relaxations and the trapping mechanisms.