Anion-exchange separation and spectrophotometric determination of vanadium in silicate rocks

A combined anion-exchange-spectrophotometric method has been developed for the determination of vanadium in silicate rocks. A rock sample weighing about 0.1 g is decomposed with a mixture of sulphuric and hydrofluoric acids and after removal of HF the residue is taken up with dilute sulphuric acid. This solution is adjusted to be 0.05M in sulphuric acid and contain 0.3% hydrogen peroxide, and is passed through a column of Amberlite CG 400 (sulphate form). The sorbed vanadium is eluted with 30 ml of 1M hydrochloric acid. The effluent is evaporated to dryness, made 0.1M in hydrochloric acid and 3% in hydrogen peroxide content, and passed through a column of Amberlite CG 400 (chloride form) to get rid of accompanying thorium and zirconium. Vanadium is stripped by elution with 20 ml of 1M hydrochloric acid and subsequently determined spectrophotometrically with 4-(2-pyridylazo)resorcinol. The detection limit is 0.4 ppm.     

Room-temperature phosphorimetric determination of biogenic indole compounds adsorbed on a thin-layer chromatographic plate

A simple and sensitive method is described for the determination of biogenic indole compounds adsorbed on cellulose or alumina plates for thin-layer chromatography by room-temperature phosphorimetry. The optimum conditions were investigated for 5-hydroxyindole-3-acetic acid and indole-3-acetic acid. The compounds are spotted on the plates, which are then sprayed successively with sodium citrate or sodium acetate, and sodiu iodide solutions. The plates are dried completely under a stream of dry nitrogen, and immediately dipped in molten paraffin. The phosphorescence is stable for at least 3 h even in moist air. The limits of detection for nine biogenic indole compounds tested are between 2 and 300 pmol per sample spot.     

High-Density Excitons in a Diluted Magnetic Semiconductor: Cd 1 − x Mn x Te

Time-resolved magneto photoluminescence in a diluted magnetic semiconductor Cd 0.9 Mn 0.1 Te has been carried out with varying exciton density from 10 14 to 10 19 cm m 3 . The reduction of the Zeeman shift and that of the magnetic polaron energy was found under strong photoexcitation. The spectral feature is interpreted in terms of the heating of the manganese spin subsystem. Polarization dependence of the spin heating is observed for the first time, revealing the contribution of the spin flip between excitons and magnetic ions to the heating process.     

Single Nucleotide Polymorphism Typing with a Surface Plasmon Resonance-Based Sensor Using Hybridization Enhancement Blockers

We constructed a simple method for discrimination of single nucleotide polymorphism (SNP) with a surface plasmon resonance (SPR)-based sensor by determining the binding volume (BV) between a target SNP allele and a probe complementary to the target. In the method, a novel additive termed “blocker,” which is a short single-stranded DNA complementary to the target, was used. The blocker enhanced the BV of the target only to the full-match probe 10-fold or more, so the SNP alleles could be discriminated readily. The effect of the blocker concentration was also examined. The BV to only a full-match probe increased with increasing the blocker concentration and reached a plateau at the concentration of 300–500 nM. To assess the effectiveness of this method, the SNP associated with progressive rod-cone degeneration in dog was determined. The results of genotyping with the method were in good agreement with those obtained by direct sequencing.     

Molecular Chirality Recognized by Achiral Compounds

Abstract

Three cases are described where chirality is recognized by achiral molecules, where chirality is induced into achiral compounds through interactions with chiral compounds, and lastly where induced chirality in the solid-state is utilized for an enantio-selective photoreaction. In the first instance, the thermodynamically and kinetically preferred diastereoisomer of an optically labile chromium complex depended on the nature of the achiral solvent. In the second case, for the first time 1,2-chloroethane was trapped and observed in a chiral near-eclipsed form and 1-chloropropane in the truly eclipsed form at room temperature in a 1:1 inclusion complex with an optically active host molecule. Finally, induced chirality in a prochiral compound in the solid-state was successfully employed in an enantio-selective photoreaction. In the two cases, solid-state CD provided valuable information.     

A Synthetic Method for Preparing 3,3-Dialkyl-1,2,3,8-tetrahydroazulen-1-one

The trimethylsilyl enol ether of l-acetylcyclohepta-1,3,5-triene was transformed to 3,3-dialkyl-1,2,3,8-tetrahydroazulen-1-one by a two-step sequence involving the Mukaiyama aldol reaction with ketones and the subsequent Nazarov cyclization.     

Enormously extended π-electronic conjugation system of dimeric octaethylporphyrin transmitted with anthracene

Based on the fact that anthracene (Anth) possesses much higher similarity in electron-releasing ability to porphyrin nucleus than the other polyacenes, the dimeric octaethylporphyrin (OEP) derivatives 4 and 5 (OEP–Anth–OEP) were synthesized and their structure–property relationships were examined, as compared with related OEP dimers 1–3. Among them, the derivative 4 showed enormously high electronic communication between two terminal OEP rings, potentially providing a suitable unit of the electronic structure for molecular design of the OEP devices operating with less energy and with higher sensitivity to outside stimuli.