Quantitative Transfer of In-Gel Digest Products to Liquid Chromatography-Electrospray Mass Spectrometry Using On-Line Coupled Extraction

A system is described for the on-line extraction of a digested protein in a gel spot. The extract obtained was on-line transferred to a precolumn, used to desalinate and preconcentrate the sample. The precolumn was switched in-line with an LC-ESI-MS system to separate the digest products prior to detection. By using this approach sample losses were minimized and the sample was quantitatively transferred. The benefits of the system were shown for the in-gel tryptic digest of several model proteins. Using this system, the sensitivity was 13-fold increased compared to the off-line extraction of in-gel digest products leading to a higher sequence coverage and thus a better identification potential. Also, the within day repeatability was a factor 2.5 improvement using the on-line procedure compared to the off-line extraction procedure.     

Imidazole facilitates electron transfer from organic reductants

In cyclic voltammetry studies at pH 8, imidazole facilitates oxidation of organic compounds that normally lose hydrogen atoms. High concentrations of imidazole shift the oxidizing wave of ascorbic acid, 2,3-dimethoxy-5-methyl-1,4-hydroquinone, and the vitamin E analogue Trolox toward lower potentials. By contrast, imidazole has no effect on the cyclic voltammogram of methyl viologen, which undergoes electron rather than hydrogen-atom transfer. The effect of imidazole is observed at pH 8.0 but only to a lesser extent at pH 5.5 indicating that imidazole must be unprotonated to facilitate oxidation. Digital simulation shows that these results are consistent with a mechanism in which imidazole acts as a proton acceptor permitting concerted proton/electron transfer by the organic reductant.     

碱金属和重金属叠氮化物的感度和导电性研究

分别用EHCO和DV－X_α方法，计算研究了α－NaN_3、β-NaN_3和AgN_3的能带结构和原子簇电子结构. AgN_3与NaN_3相比：带隙(△Eg)较小、带宽(BW)较大，因而电导率较大. 比较前沿晶体轨道(CO)和前沿分子轨道(MO)的能级、组成及电子在其间的跃迁；预示AgN_3比NaN_3更敏感、更易分解和起爆．还从电子微观层次揭示了金属叠氮化物的导电性和爆炸性之间的联系．     

白卡奴鸽动脉粥样硬化模型微量元素谱的计算机多元分析

用ＩＣＰ－ＡＥＳ测定了白卡奴鸽动脉粥样硬化模型和对照组的器官和组织中１９种元素含量，通过因子分析，取得一系列因子得分图，结果表明，动脉粥样硬化和对照组样品点分布在不同区域，且可分辨。     

High performance organic field-effect transistors based on amphiphilic tris(phthalocyaninato) rare earth triple-decker complexes

LB films of three amphiphilic tris(phthalocyaninato) rare earth triple-decker complexes with crown-ethers as hydrophilic heads and long alkyl chains as hydrophobic tails have been prepared and found to display very well ordered layer structures, as proved by pi-A isotherms, UV-vis and polarized absorption spectra, X-ray diffraction experiments, and microscopic morphology characterization. These LB films have been fabricated into field-effect transistor (FET) devices, which show carrier mobilities as high as 0.24-0.60 cm2 V-1 s-1, among the highest mobilities achieved thus far for all LB film-based OFETs.     

Synthesis and Crystal Structure of Mixed-Ligand Ni(II) Complex of N-(1-Phenyl-3-methyl-4-benzylidene-5-pyrazolone) p-Nitrobezoylhydrazide and Pyridine

A novel mixed-ligand nickel complex, [Ni(PMBP—PNH) (Py)₃], [PMBP—PNH=N-(1-phenyl-3-methyl-4-benzylidene-5-pyrazolone) p-nitrobezoylhydrazide; Py = pyridine], has been synthesized by the hydrothermal method and characterized by elemental analysis, IR spectrum, thermal analysis, and single-crystal X-ray diffraction. The X-ray diffraction reveals that the nickel (II) ion in the title complex is in a slightly distorted octahedral arrangement of the ONO donor atoms of primary ligand PMBP-PNH and three N-donor atoms in the secondary ligand pyridine.     

Phase Selectively Soluble Dendritic Derivative of 4-(Dimethylamino)- pyridine: An Easily Recyclable Catalyst for Baylis-Hillman Reactions

Among the reactions in which C-C bonds are formed, the Baylis-Hillman coupling of aldehydes with α, β-unsaturated carbonylic compounds is currently attracting much interest due to the atom economy, the mild conditions and the generation of functional groups1,2. Furthermore, compared to the Heck, Suzuki and other palladium catalyzed C-C bond forming reaction3, the Baylis-Hillman reaction can be promoted by using organic bases in the complete absence of any metal4. However, almost all the …     

偏最小二乘及双波长K系数光度法同时测定矿物中钛,铁

本文运用化学计量学中的偏最小二乘法及双波长Ｋ系数法实现了Ｔｉ、Ｆｅ的同时测定，方法用于铝钒土及钛铁矿中Ｔｉ、Ｆｅ同时测定，结果满意。     

硼烷结构规则的量子化学计算

利用EHMO方法,对n=5～12的完整多面体硼烷骨架、缺一个和两个顶点以及戴一个和两个帽原子的各种异构体进行了量子化学计算。直接对硼烷的价成键轨道数公式BMO=4n-[f+3(s+1)]进行了验证。在对计算结果讨论的基础上,进一步探讨了骨架几何结构与成键轨道数之间的关系。     

偶极积分与Boys法分子轨道定域化

定域分子轨道在分子体系的化学图象和物理图象之间充当重要的桥梁作用,它的产生依赖于定域化准则,其中最普遍使用的是Foster-Boys和Edmiston-Ruedenberg(E—R)提出的两种定域化准则。这两种定域化准则是等价的,因而结果也是一致的。但对于E—R定域化来说,由于涉及到大量的多中心积分的计算,计算极为费时,因而远不如Foster-Boys定