One-electron oxidation of the iron(II) complex of 1,10-phenanthroline-5,6-quinone A pulse radiolysis study

One-electron oxidation of the ferrous tris-PQ complex, a model for lipoxygenase, was attempted using oxidants such as •OH, N^•₃, Br^•-₂, Tl²⁺ and TlOH⁺. •OH was found to react with the complex with a bimolecular rate constant of (3.9±0.6)x10⁹dm³mol^-1s^-1, a rate which is not very dissimilar to that for the reaction with the ligand PQ. However the product of the reaction was found to be a OH-adduct rather than a cation radical. No reaction was found to occur with N^•₃ or Br^•-₂. Both Tl²⁺ and TlOH⁺ reacted with the complex to form its oxidised species with rate constants of (7.0±1)x10⁸dm³mol^-1s^-1 and (4.0±0.8)x10⁸dm³mol^-1s^-1, respectively. From a comparison of the rate constants and the transient spectra it was concluded that the centre of oxidation is the ligand rather than the metal.     

环氧烷化合物在有机合成中的应用

综述了近年来环氧烷化合物在有机合成中的应用。环氧烷化合物的开环反应可以用来合成其它方法难以合成的多官能团化合物，或通过开环和修饰合成其他环状化合物。另外，利用该反应还可以提供保护基以及立体、区域选择性地合成各种有机化合物。参考文献23篇。     

有机元素微量分析标准物质——茴香酸的研制

茴香酸的分子式为C_8H_8O_3,碳含量63.15%、氢含量5.30%、氧含量31.55%、甲氧基含量20.40%。该标样与日本元素分析恳谈会委员会、英国化学协会微量化学委员会所公布的微量化学标样之一——香草醛一样,都具有相同的碳、氢、氧和甲氧基含量,美国国家标准局(NBS)发行SRM142茴香酸作为微量分析中甲氧基的分析标样。     

A new study of the enzymatic hydrolysis of carboxymethyl cellulose with a bulk acoustic wave sensor

A new bulk acoustic wave (BAW) cellulase sensing technique, which is based on the enzymatic hydrolysis process of sodium carboxymethylcellulose (CMC) by cellulase, was established. The frequency shift curves of BAW sensor indicated that the viscosity of the tested solutions decreased during the hydrolysis process. The hydrolysis rate of CMC by cellulase was calculated from the frequency shift curves. The hydrolysis rate of CMC under different pH conditions at 30°C showed that cellulase had high hydrolysis ability approximately at pH 5.0. Kinetic parameters (the Michaelis constant K_m and the maximum rate V_max) of the process were estimated by using a linear method of Lineweaver–Burk plot. K_m is 1.95±0.25 mg ml⁻¹ and V_max is −(4.25±0.58)×10⁻³ g^1/2 cm^−3/2 cP^1/2 min⁻¹. Also the activation energy (E_a) of the enzymatic hydrolysis, with a value of 51.99±1.26 kJ mol⁻¹, was estimated in this work.     

Rapid detection of Escherichia coliform with a bulk acoustic wave sensor based on the gelation of Tachypleus amebocyte lysate

A new sensing method (BAW-TAL technique), which combined the bulk acoustic wave (BAW) technique with the gelation reaction of Tachypleus amebocyte lysate (TAL), was used for viscosity and density measurement and applied to the detection of Escherichia coliform (E. coli). This method depended on the fact that the viscosity and density of the mixture increased, and as a result, the resonance frequency decreased correspondingly after TAL was mixed with the heated E. coli solution that contained endotoxin. Results showed that the frequency shift was linearly related to the logarithm of E. coli concentration in the range of 2.7x10(4)-2.7x10(8) cells/ml. The correlation coefficient was 0.996. This BAW-TAL method was compared with the standard pour plate counts (PPC) method. The proposed method was much more rapid and simpler for detection of E. coli than the traditional methods.     

Systematic studies of fission fragment kinetic energy distributions by Langevin simulations

Fission fluctuation-dissipation dynamics of heavy nuclei has been studied using Langevin Monte Carlo simulations. The covariant form of the fission transport equation and the coefficients related to it are investigated. To learn about the influence of the dynamics from the ground state to the saddle point on the kinetic energy distributions we have studied various systems and compared the calculations both starting from the ground state and from the saddle point. Both the mean total kinetic energy of the fission fragments and its variances can fit with the experimental values in terms of a finite neck radius as scission condition.This work was supported by the National Natural Science Foundation of China.