Modelling of point defects in monoclinic zirconia

We present the results of plane wave density functional theory calculations of oxygen vacancies and interstitial oxygen atoms in monoclinic zirconia. After calculating the incorporation energies and structures of interstitial oxygen atoms and formation energies of neutral oxygen vacancies, we consider the electron affinities and ionisation potentials of these defects. These properties are especially important at the silicon/oxide interface in MOSFET devices, where silicon may serve as an electron and hole source. The results demonstrate that interstitial oxygen atoms and positively charged oxygen vacancies can trap electrons if the electron source (band offset) is higher than ∼2 eV above the top of the zirconia valence band.     

Simultaneous determination of swertiamarin and its metabolites (5Z)-5-ethylidene-8-hydroxy-3,4,5,6,7,8-hexahydro-1H-pyrano[3,4-c]pyridin-1-one and erythrocentaurin in broth of Aspergillus niger by HPLC

When cultivated with Aspergillus niger, swertiamarin, an important drug, is rapidly transformed into erythrocentaurin and (5Z)-5-ethylidene-8-hydroxy-3,4,5,6,7,8-hexahydro-1H-pyrano[3,4-c]pyridin-1-one (M(1)), a new compound with high anti-inflammatory activity. A simple and rapid HPLC method for simultaneous determination of swertiamarin and its two metabolites in broth of A. niger is described. The chromatographic separation was achieved on a C(18) ODS column (250 x 4.6 mm i.d.) by gradient elution with 0.04% formic acid in water and 0.04% formic acid in acetonitrile as the gradient mixtures. The flow rate was 1 mL/min, the detection wavelength was 237 nm and the column temperature was kept at 30 degrees C. The retention times of swertiamarin, erythrocentaurin and M(1) were 14.6, 16.8 and 24.8 min, respectively. The mean absolute recoveries of three analysts were over 96%. Quantification limits were 0.02 microg/mL for swertiamarin and 0.05 microg/mL for both of the two metabolites. The method was applied for the quantification of swertiamarin and its two metabolites during the fermentation process and the evaluation of the bioavailabilities in the Caco-2 monolayer.     

Complete 1H and 13C NMR assignments and Z/E-stereoconfiguration determination of isomers of 1,4-diketone derivatives

Complete 1H and 13C NMR assignments and Z/E-stereoconfiguration determination for a series of new isomers of 1,4-diketone derivatives obtained via self-sorting tandem reaction were accomplished by means of one- and two-dimentional NMR experiments including 1H, 13C, gCOSY, gHSQC, gHMBC, and NOESY.     

The role of aromatic groups in the Tobey-Simon additivity rule for vinylic protons

The Tobey-Simon (additivity) rule for aromatic groups which was devised about 40 years ago has been found to need revision. The rule shows an aromatic group attached to a C==C double bond as causing a downfield chemical shift of a cis-related vinylic proton and a small upfield shift of a trans-related proton. A search of data in the recent literature has shown that this rule should apply mainly to monosubstituted phenyl groups and some polynuclear aromatics. In contrast with them, 2,6-disubstituted phenyl, 2,4,6-trisubstituted phenyl and 9-anthracenyl groups cause cis-related vinylic protons to resonate upfield of comparable trans-related protons. Further, the current rule for o-substituted phenyl groups has been found to be inaccurate. In writing a rule for aromatic groups, therefore, greater attention needs to be given to the diversity of effects that these groups have on chemical shifts of vinylic protons.     

Pulsed laser evaporation: equation-of-state effects

Theoretical study of laser ablation is usually based on the assumption that the vapor is an ideal gas. Its flow is described by gas dynamics equations [1, 2]. The boundary conditions at vaporization front are derived from the solution of the Boltzmann equation that describes the vapor flow in the immediate vicinity of the vaporizing surface (so-called Knudsen layer) [1]. This model is applicable within the range of temperatures much lower than the critical temperature of target material. In the present work, a general case is considered when the temperature of the condensed phase is comparable to or higher than the critical temperature. The dynamics of both condensed and gaseous phases can be described in this case by the equations of hydrodynamics. The dynamics of vaporization of a metal heated by an ultrashort laser pulse is studied both analytically and numerically. The analysis reveals that the flow consists of two domains: thin liquid shell moving with constant velocity, and thick low-density layer of material in two-phase state. Received: 2 March 1999 / Accepted: 28 May 1999 / Published online: 21 October 1999     

薄层色谱法分离烷基芳基酮肟立体异构体

我们对酮肟中间体及肟醚类拟除虫菊酯进行了分析。经核磁共振证明,酮肟中间体在生成肟醚南反应过程中其立体构型木发生变化。目前分离酮肟立体异构物的工作报道较少。我们通过薄层色谱对不同取代的具有活性的几种酮肟异构体的分离进行了探讨。 1 实验部分     

One-pot synthesis of(Z)-4-(2-bromovinyl)benezenesulfonamides by microwave-induced simultaneous debrominative decarboxylation and sulfamation of anti-2,3-dibromo-3-(4-chlorosulfonylphenyl)propanoic acid

One-pot simultaneous debrominative decarboxylation and sulfamation of anti-2,3-dibromo-3-(4-chlorosulfonylphenyl)propa-noic acid in DMF (for alkyl amines) or DMF-pyridine (for aryl amines) using a diverse range of alkyl and aryl amines under microwave irradiation condition stereoselectively afforded (Z)-4-(2-bromovinyl)benzenesulfonamides in good yields.     

QD128燃气轮机发电机组在超大型IDC／EDC机房的应用

简要介绍了QD30C和QD128燃气轮机发电机组的构成和主要技术参数,初步探讨了QD30C和QD128燃气轮机发电机组在超大型IDC／EDC机房的配置。提出了QD128燃气轮机发电机组在超大型IDC／EDC机房应用的建议。     

某市数据中心供电规划

为进一步推动中国移动集中化,实现低成本高效运营,中国移动借鉴国内外成功经验,探索研究中国移动未来的集中化建设,提出建设专业化、集中化和低成本化的IDC基地。本文针对数据中心选址和供电规划要点,提出其市电引入规划和供电规划思路。