On Potentially Abelian Geometric Representations

The finiteness is proved of the set of isomorphism classes of potentially abelian geometric Galois representations with a given set of data. This is a special case of the finiteness conjecture of Fontaine and Mazur.     

Achievement of laser fusion of biological cells using UV pulsed dye laser beams

This paper reports a successful achievement of laser-induced biological cell fusion using an excimer laser excited dye laser. To our knowledge, we examined for the first time the dependence of fusion rate on laser pulse energy, number of laser pulses, and laser wavelength. Maximum fusion rate of approximately 50% was obtained by this laser fusion technology.     

Micro-phase sorbent extraction for trace analysis via in situ sorbent formation: application to the spectrophotometric determination of nitrite in environmental waters.

A micro-phase sorbent in situ formation from an aqueous solution was proposed for the sensitive spectrophotometric determination of nitrite in environmental waters. Nitrite in a 10 mL sample solution was converted into a cationic azo dye by the reaction with 4-trifluoromethylanilinium ion and N-1-naphthylethylenediammonium ion in an acidic medium. Addition of dodecylbenzenesulfonate ion caused the formation of a suspension of ion associate in the solution. Centrifugation of the solution led to the isolation of a liquid organic phase that extracted the azo dye at the bottom of the centrifuge tube. The volume of the new phase was ca. 5 microL. After the aqueous phase was discarded, the organic phase was dissolved with 1 mL of 2-methoxyethanol to measure the absorbance. Nitrogen as NO2- at concentrations from 1.5 to 30 microg L(-1) was determined with sufficient precision. When 0.2 mL of 2-methoxyethanol was applied to dissolve the organic phase, 0.3-4.8 microg NO2--N L(-1) was determined. The recovery tests for nitrite added to some river water and seawater were satisfactory. This method is very simple and rapid. It takes only 30 min from the dye formation to the measurement of the absorbance.     

Lewis acid promoted reactions of γ,γ-dialkoxyallylic zirconium species with various carbonyl compounds

The reactions of γ,γ-dialkoxyallylic zirconium species with carbonyl compounds in the presence of Lewis acid are reported. The reactivity of γ,γ-dialkoxyallylic zirconium species and reaction pathway were strongly dependent on the structure and electrostatic nature of the carbonyl compounds.     

Action of phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis is significantly influenced by coexisting lipids in substrate-detergent micelles.

The effects of phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyelin (SM), and cholesterol on the activity of phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus thuringiensis were studied in detail in phosphatidylinositol (PI)/detergent mixed micelles. By addition of PC, the enzymatic hydrolysis of PI was significantly stimulated in PI/Triton X-100 as well as PI/sodium deoxycholate (SDC) mixed micelles. SM stimulated enzyme activity toward PI/Triton X-100 micelles at a lower molar ratio of SM to PI, but was rather inhibitory at a ratio higher than 2.0. The enzyme activity became significantly lower with an increase of PE or cholesterol in PI/Triton X-100 micelles. Actually, both PE and cholesterol were intensively inhibitory when added at a higher molar ratio to PI in Triton X-100-containing micelles. In the system of PI/SDC mixed micelles, not only PC but also SM, PE and cholesterol enhanced the enzymatic hydrolysis of PI. The difference between PI/Triton X-100 and PI/SDC micelles regarding the effects of these lipids on PI-PLC action, must be dependent on the physical state of micelles formed by these detergents and lipids.     

Rapid ruthenium-catalyzed synthesis of pyranopyrandiones by reconstructive carbonylation of cyclopropenones involving C[bond]C bond cleavage

Pyranopyrandiones were prepared by a novel ruthenium-catalyzed carbonylative dimerization of cyclopropenones via C-C bond cleavage. For example, treatment of dipropylcyclopropenone with a catalytic amount of Ru3(CO)12 and NEt3 in THF under 15 atm of carbon monoxide at 140 degrees C for 20 h gave a novel functional monomer, 3,4,7,8-tetrapropylpyrano[6,5-e]pyran-2,6-dione, in an isolated yield of 81%. Unsymmetrically substituted pyranopyrandiones were also obtained by ruthenium-catalyzed carbonylative coupling of cyclopropenones with alkynes under similar reaction conditions.     

Determination of trace moisture in hydrogen chloride gas by Karl Fischer titration

Moisture of several ppm in hydrogen chloride gas has been accurately determined by a new method using the Karl Fischer reagent, which hitherto had a limitation in accuracy because of a partial reaction with hydrogen chloride when direct titration was employed.The moisture in the sample gas was collected in a cold trap kept at about ?80 °C while the hydrogen chloride gas passed through and the frozen moisture was dissolved by pyridine-methanol (1:1) solvent. a KF Reagent of factoe: 0.35 mg H₂O/ml.Titration by the Karl Fischer reagent having the equivalency factor of, e.g., 0.5 mg H₂O/ml was carried out and the concentration of the moisture was calculated from the sample volume used.     

Radical [3 + 2] cycloaddition reaction with various alkenes using iodomethylcyclopropane derivatives as new homoallyl radical precursors

Radical iodine atom transfer [3 + 2] cycloaddition with various alkenes using dimethyl 2-(iodomethyl)cyclopropane-1,1-dicarboxylate and 1,1-bis(phenylsulfonyl)-2-(iodomethyl)cyclopropane as new precursors of a homoallyl radical species smoothly proceeds to give functionalized cyclopentane derivatives in good yields.