Theoretical study of the mechanism of acetaldehyde hydroxylation by compound I of CYP2E1

Recent experimental studies revealed that cytochrome P450 2E1 (CYP2E1) could metabolize not only ethanol but also its primary product, acetaldehyde, accompanying the well-known acetaldehyde dehydrogenases (ALDH) in the metabolism of acetaldehyde. Mechanistic aspects of acetaldehyde hydroxylation by Compound I model active species of CYP2E1 were investigated by means of B3LYP DFT calculations in the present paper. Our study results demonstrate that acetaldehyde hydroxylation by CYP2E1 is in accord with the effectively concerted mechanisms both on the high quartet spin state (HS) and on the low doublet spin state (LS). The rate-limiting step is H-abstraction, and the activation energy is about 11.7 approximately 14.0 kcal/mol on the quartet (doublet) reaction route, which is about one-half to one-third of that needed by methane hydroxylation. The phenomenon that the HS and LS reaction routes are both effectively concerted was shown for the first time to occur in trans-2-phenyl-iso-propylcyclopropane hydroxylation by Kumar et al. (see Figure 7 in the paper of Kumar, D.; de Visser, S. P.; Sharma, P. K.; Cohen, S.; Shaik, S. J. Am. Chem. Soc. 2004, 126, 1907) and was confirmed in our work of acetaldehyde hydroxylation by cytochrome P450. Theoretical exploration of the HS O-rebound barrier degradation is also presented in the present paper on the basis of Shaik's valence bond (VB) model.     

Heterogeneous electron-transfer kinetics for ruthenium and ferrocene redox moieties through alkanethiol monolayers on gold

The standard heterogeneous electron-transfer rate constants between substrate gold electrodes and either ferrocene or pentaaminepyridine ruthenium redox couples attached to the electrode surface by various lengths of an alkanethiol bridge as a constituent of a mixed self-assembled monolayer were measured as a function of temperature. The ferrocene was either directly attached to the alkanethiol bridge or attached through an ester (CO(2)) linkage. For long bridge lengths (containing more than 11 methylene groups) the rate constants were measured using either chronoamperometry or cyclic voltammetry; for the shorter bridges, the indirect laser induced temperature jump technique was employed to measure the rate constants. Analysis of the distance (bridge length) dependence of the preexponential factors obtained from an Arrhenius analysis of the rate constant versus temperature data demonstrates a clear limiting behavior at a surprisingly small value of this preexponential factor (much lower than would be expected on the basis of aqueous solvent dynamics). This limit is independent of both the identity of the redox couple and the nature of the linkage of the couple to the bridge, and it is definitely different (smaller) from the limit derived from an equivalent analysis of the rate constant (versus temperature) data for the interfacial electron-transfer reaction through oligophenylenevinylene bridges between gold electrodes and ferrocene. There are a number of possible explanations for this behavior including, for example, the possible effects of bridge conformational flexibility upon the electron-transfer kinetics. Nevertheless, conventional ideas regarding electronic coupling through alkane bridges and solvent dynamics are insufficient to explain the results reported here.     

Synthesis and luminescence of zinc and europium alpha-thiophene carboxylate polymer

The zinc and europium alpha-thiophene carboxylate polymer with very strong red luminescence was prepared by rheological phase reaction method from zinc acetate, europium oxide and alpha-thiophenecarboxylic acid. Molecular weight, thermal analyses and X-ray diffraction pattern were measured. 1H NMR, 13C NMR, IR, XPS, UV, excitation and emission spectra were studied. The polymer with amorphous structure and 7.565x10(5) g/mol weight-average molecular exhibited excellent solubility in common organic solvents and better thermal stability under 270 degrees C in air. The quantum yield of the polymer in acetone was 0.6 relative to quinoline in 0.05 mol/l H(2)SO(4) solution. The energy of the pi,pi(*) excited state of C(4)H(3)SCO(2)(-) can be transferred to Eu(3+) ion resulting in emission from the 5D(0)-->(7)F(j) of Eu(3+) ion through the polymeric chains. Zn(2+) can effectively enhance the luminescence of Eu(3+) in alpha-thiophenecarboxylate polymer.     

Preparation, thermal decomposition and lifetime of Eu(III)-phenanthroline complex doped xerogel

The main purpose of this work is proposing a new method of using non-isothermal formal kinetics analysis to predict the lifetime of luminescent complex materials. The Eu(III)-phenanthroline complex doped xerogel has been in situ synthesized by a catalyst-free sol-gel method. The photoluminescence spectra and TG curves of the xerogel verify the formation and decomposition of Eu(III)-phenanthroline complex in xerogel. The decomposition of the xerogel formally occurs in three steps. The Friedman and FWO isoconversional methods and multivariate non-linear regression method are used for formal kinetic analysis. The overall decomposition process below 800 °C is fitted by three-step consecutive reaction. The best fitted model for each step is F_n (n order reaction, the corresponding function f(α) is (1 − α)ⁿ). Correlation coefficient is 0.99956. The lifetime values of xerogel at different temperatures are predicted based on non-isothermal kinetic models by the 5% decomposition of europium organic complex.     

Application of dynamical Lie algebraic method to atom–diatomic molecule scattering

The dynamical Lie algebraic approach developed by Alhassid and Levine combined with intermediate picture is applied to the study of translational–vibrational energy transfer in the collinear collision between an atom and an anharmonic oscillator. We find that the presence of the anharmonic terms indeed has an effect on the vibrational probabilities of the oscillator. The computed probabilities are in good agreement with those obtained using exact quantum method. It is shown that the approach of dynamical Lie algebra combining with intermediate picture is reasonable in the treating of atom–anharmonic oscillator scattering.     

单光子LIF方法研究亚硝基苯266 nm光解动力学

用266 nm激光解离亚硝基苯（C6H5NO) 产生光解碎片NO,并利用单光子激光诱导荧光(LIF)技术（X2Πν″=0→A2Σ+ν′=0）测得初生态光解产物NO的振转光谱。根据计算所得的模拟光谱对光解碎片NO（X,ν″＝0)的转动量子数J″进行了归属,得到量子数最大到J″＝50.5的各转动能级的相对布居,这表明光解碎片NO具有较高的转动激发。提出了C6H5NO在266 nm下可能的光解机理。     

CoMoS<Subscript>4</Subscript> Nanoflowers as Anode for Secondary Lithium Batteries

CoMoS₄ nanoflowers was synthesized by precipitation method from Na₂MoO₄, CoCl₂ · 6H₂O and CH₃CSNH₂ as starting materials. X-ray diffraction (XRD) analysis showed that the prepared samples is amorphous structure, X-ray photoelectron spectrometer data of Co, Mo and S in CoMoS₄ revealed that the valences of the corresponding elements are almost +2, +6, and −2, respectively. Scanning electron microscope gave the result that the morphologies of the as-prepared powder is flower-like nanostructure. Moreover, electrochemical tests were also carried out, the initial discharge was 1547 mA h g⁻¹, even after 20 cycles, it still remains 461 mA h g⁻¹.     

ClO/ClO~-耦合体系结构性质及反应通道研究

利用从头算法和密度泛函理论对ClO/ClO~-体系进行了研究。首先应用密度泛 函理论的六种方法(B3LYP,BLYP,B3P86,BP86,BHLYP,LSDA)和从头算理论的CCSD方法 在6-3+G~*,6-311+G~*及6-311+G(3df)基组水平上对单体进行了优化,选出最适合 该体系的方法和基组B3LYP/6-311+G(3df);然后在B3LYP/6-311+G(3df)水平上计算 了沿各种反应通道的离解能,并且进行了校正。找出了存在的中间体及中间体异构 化的过渡态,并进行了IRC路径解析。对各稳定体进行了频率分析和成键分析。结 果表明,单体ClO和单体ClO~-结合为稳定的中间体后,其离解方式主要是向着 ClOO+Cl~-和ClOO~-+Cl两种方式进行,两种离解方式的离解能分别为-33.39和82. 88kJ/mol,并且前者是一个离解性电子转移过程,经历一个电子转移过渡态。     

关于超代数$(\alpha,\beta,\gamma)$-超导子的一个注记

This paper is concerned with two results for （α, β, γ）-superderivations of general superalgebras over the field of complex numbers.