CaL-B a highly selective biocatalyst for the kinetic resolution of furylbenzthiazole-2-yl-ethanols and acetates

A highly stereoselective enzymatic kinetic resolution of novel various substituted racemic furylbenzthiazole-2-yl-ethanols and their acetates has been developed. Both processes, the enzymatic acylation of the racemic alcohols and the enzymatic methanolysis of racemic acetates yielded highly enantiomerically enriched (ee >98%) resolution product, when CaL-B was used as a biocatalyst in acetonitrile. The absolute configuration of the obtained (R)-(+)-1-(5-(4-chlorobenzo[d]thiazol-2-yl)furan-2-yl)ethanol was determined by a detailed ¹H NMR study of rac- and (+)-1-(5-(4-chlorobenzo[d]thiazol-2-yl)furan-2-yl)ethanol Mosher derivatives.     

An amperometric ethanol sensor based on foam nickel electrode

An amperometric sensor using foam nickel electrode as the working electrode for the measurement of ethanol in alkaline solution has been developed. Cyclic voltammetry and chronoamperometry are employed to analyze electrochemical behavior of the electrode. The results show that the oxidation of ethanol is more efficient on the foam nickel electrode than that on the nickel foil electrode. The sensor exhibits a good linear relationship between response current and ethanol concentration in the range of 4 to 1400 ppm with a detection limit of 0.8 ppm. The sensitivity and the response time of the sensor are 4.63 μA/ppm and 10 s respectively. Additionally, the sensor has 60 days shelf-life time at least.     

Evaluating the Thermal Hazard of Double-Base Propellant SQ-2 by Using Microcalorimetry Method

The thermal decomposition behavior of double‐base rocket propellant SQ‐2 was studied by a Calvet microcalorimeter at four different heating rates. The kinetic and thermodynamic parameters were obtained from the analysis of the heat flow curves. The critical temperature of thermal explosion (T_b), the self acceleration decomposition temperature (T_SADT), the adiabatic decomposition temperature rise (ΔT_ad), the time‐to‐explosion of adiabatic system (t), critical temperature of hot‐spot initiation (T_cr), critical thermal explosion ambient temperature (T_acr), safety degree (SD) and thermal explosive probability (P_TE) were presented to evaluate the thermal hazard of SQ‐2.     

Oxidation effect on double H-bonded imidazole–adenine–imidazole trimer

The geometry, the IR spectra, the molecular orbital, and the related energy of the planar double hydrogen-bonded imidazole–adenine–imidazole trimer are investigated employing the reliable B3LYP/6-311+G* method. The H bonds generated by NH group of adenine reduce significantly upon oxidation and the H atoms transfer in different degree for three isomers. Significant IR spectra red-shift occurs upon oxidation for all N–H···N H bonds. The HOMO orbital is employed to explain the variation of H-bond alkalescence, as is effective to reveal the geometry variations and the IR spectra shifts. The adiabatic ionization potential obtained in experiment should be lower than our reported value for the possible higher degree of polymerization.     

Taxayuntin I from Thous Yunnanensis

Sinceexcellentantitumoractivityanduniquemechanismofactionofpaclitaxel(taxol@)werediscovered,chemicalstudiesonTaxusspecieshavebeenextensivelycarriedoutl'2.About300taxoidshavebeenisolatedfromGeneraTaxusandAustrotaxusplants'.Insearchforbioactivetaxoidsa...     

Solvent Effects on Aza‐anionic Cycloaromatization of 2‐(2‐Substituted‐ethynyl)benzonitriles

The methanolysis of 2‐(2‐aryl ethynyl)benzonitriles is accelerated when the polar aprotic solvents are added, which could enhance the 6‐endo pathway and give isoquinolones, though the 5‐exo pathway is occupied mostly. The yields of products would also be in creased.     

Bistable reflectivity in bulky semiconductors due to two photon-biexciton transitions

A new mechanism has been proposed for optical bistability in a bulk system of interacting photons and biexcitons. Bistable behaviour can occur for very low pumping intensities if the input light frequency is clearly less than the two-photon resonance of the biexciton.     

智能化霍尔效应实验仪

本文介绍了单片计算机控制的组合多功能霍尔效应实验仪的原理、结构、功能特点。