Hydrothermal in situ synthesis and characterization of Cu(II) complexes

The hydrothermal in situ Cu(II)/2,3-pyrazine dicarboxylic acid reactions at 100 and 140 degrees C result in Cu(II) 3-hydroxy-2-pyrazinecarboxylate and oxalate complexes, respectively. This is the first example of a combination of experimental and theoretical study on in situ metal/ligand reactions under hydro- and solvothermal conditions.     

Establishment of a Charge Reversal Derivatization Strategy to Improve the Ionization Efficiency of Limaprost and Investigation of the Fragmentation Patterns of Limaprost Derivatives Via Exclusive Neutral Loss and Survival Yield Method

Sensitivity is generally an issue in bioassays of prostaglandins and their synthetic analogs due to their extremely low concentration in vivo. To improve the ionization efficiency of limaprost, an oral prostaglandin E1 (PGE1) synthetic analog, we investigated a charge reversal derivatization strategy in electrospray ionization mass spectrometry (ESI-MS). We established that the cholamine derivative exhibits much greater signal intensity in the positive-ion mode compared with limaprost in the negative ion mode. Collision-induced dissociation (CID) involved exclusive neutral mass loss and positive charge migration to form stable cationic product ions with the positive charge on the limaprost residue rather than on the modifying group. This has the effect of maintaining the efficiency and specificity of multiple reaction monitoring (MRM) and avoiding cross talk. CID fragmentation patterns of other limaprost derivatives allowed us to relate the dissociation tendency of different neutral leaving groups to an internal energy distribution scale based on the survival yield method. Knowledge of the energy involved in the production of stabilized positive ions will potentially assist the selection of suitable derivatization reagents for the analysis of a wide variety of lipid acids.

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High-throughput bioanalysis of sitagliptin in plasma using direct analysis in real time mass spectrometry and its application in the pharmacokinetic study thereof

Sitagliptin is a dipeptidyl peptidase-IV inhibitor for the treatment of type 2 diabetes mellitus. In the present study, a sensitive and high-throughput quantitative method based on the direct analysis in real time tandem mass spectrometry has been developed and validated for the bioanalysis of sitagliptin in rat plasma without chromatographic separation. Sitagliptin and its internal standard retagliptin were detected in positive ion mode by multiple reaction monitoring transitions at m/z 408.2→235.0 and 465.2→260.1, respectively. The method includes a simple solid-phase extraction sample preparation procedure, through which appropriate and reproducible analytical results within the linear concentration range of 20–2000 ng/mL have been achieved. The intra- and interday precisions were <10.6% and the accuracies were ranging from −8.17 to 2.60%. This method has been successfully applied to the pharmacokinetic study of sitagliptin after single intravenous administration in rats. This approach shows considerable promise of direct analysis in real time tandem mass spectrometry method in the high-throughput bioanalysis.     

TEMPO-catalyzed oxidative dimerization and cyanation of indoles for the synthesis of 2-(1H-indol-3-yl)-3-oxoindoline-2-carbonitriles

A method for the combinative oxidative homo dimerization and cyanation of free indole derivatives catalysed by TEMPO along with silver carbonate was demonstrated for the first time This new methodology is both atom and step efficient and is applicable to a broad scope of substrates, allowing the synthesis of a range of synthetically valuable 2-(1H-indol-3-yl)-3-oxoindoline- 2-carbonitriles in moderate to excellent yields. Furthermore, selected compounds 6b and 6g exhibit moderate to good anti-schistosomicidal activities.     

符合ISO/IEC指南25-1990的实验室质量体系向ISO/IEC 17025-1999标准过渡的文件修改

按照ISO／IEC指南25－1990建立起较完善的质量体系的实验室,可通过对质量体系文件进行适当增补或少量删减,以实现向ISO／IEC 17025－1999标准的过渡。对质量手册,按照ISO／IEC指南25－1990的13个要素逐个讨论了具体的增删内容;对程序文件,则按ISO／IEC 17025－1999要求逐个列出了应有的程序。     

CF2BrCl分子近域轨道的电子动量谱学研究

The frontier molecular orbitals (HOMO and NHOMO) of CF2BrCl molecule have been firstly investigated by (e,2e) electron momentum spectroscopy. The experimental momentum profiles are compared with the theoretical profiles employing Hartree-Fock and density functional theory with 6-31G and 6-311+G(d) basis sets. Both HF and DFT calculations using 6-311+G(d) basis set can well describe the experiment, whereas those calculated using 6-31G basis set largely underestimate the experiment at the low momentum region. Furthermore, orbital electron density images show that HOMO and NHOMO have a mixed character of the bromine and chlorine lone pairs.     

Improved illumination for vision-based defect inspection of highly reflective metal surface

Specular and strong reflections are the main problems encountered during part image defect inspection of shiny or highly reflective surfaces. In this letter, we propose an improved illumination method for defect inspection. A diffuse light source is designed based on the physics analysis of light reflection. The distribution of intensity is simulated according to a known model to verify the illumination uniformity of the source. Experiments show that defect expressivity when using the proposed illumination method has a better performance. The optical model is not only suitable for the defect detection of metal balls but also for the defect detection of planes and cylinders.     

具有拟理想恰当断面的富足半群

利用格林*-关系刻画R和L并给出与它们相关的一些性质.利用R和L,得到恰当断面是拟理想的几个等价条件.最后,用两个结构构件R和L给出具有拟理想恰当断面的富足半群的一个结构定理.它比陈建飞在2000年给出的要简单.     

微波消解-火焰原子吸收光谱法对鼠曲草中六种微量元素的测定

用浓硝酸微波消解法处理样品,采用火焰原子吸收光谱法测定了鼠曲草全草及花中Fe、Cu、Mg、Ca、Mn、Zn6种微量元素的含量。结果表明,鼠曲草全草及花中含有丰富的人体必需微量元素,各元素的回收率在98．9％-104．0％之间。该法操作简单,结果准确,是鼠曲草中微量元素测定的理想方法。     

生姜、大蒜和辣椒中六种微量元素的测定

用浓硝酸和双氧水微波消解处理样品,采用火焰原子吸收光谱法测定了生姜、大蒜和辣椒中Fe、Cu、Mg、Ca、Mn、Zn6种元素的含量。结果表明,这3种植物中含有丰富的人体必需微量元素,样品回收率在94．O％～101．8％之间。该法操作简单,结果准确。