活性炭对丙烯酰胺单体水溶液的精制作用

活性炭对丙烯酰胺单体水溶液的精制作用李瑛＊孙文霞季鸿渐郭淑玲＊＊申花英＊＊（中国科学院长春应用化学研究所长春１３００２２）关键词丙烯酰胺，精制，活性炭１９９６－１２－１３收稿，１９９７－０６－１６修回国家“八五”攻关项目专题＊＊现在大庆油田管理局化...     

A comparative study of various computational approaches in calculating the structure of pyridoxal 5'-phosphate (PLP)-dependent beta-lyase protein. The importance of protein environment

Various computational approaches, using molecular mechanics (Amber), semiempirical (AM1), density functional (B3LYP), and various ONIOM methods, have been comparatively investigated for the structure of Escherichia coli NifS CsdB protein. The structure of the entire monomer containing 407 amino acid residues and 579 surrounding water molecules has been optimized. The full geometry optimization in the "active site-only" approach (including only active site atoms) has been found to give the largest root-mean-square (RMS) deviation from the X-ray structure; a much better agreement has been achieved by keeping the atoms leading to the backbones of some amino acids frozen in their positions in the X-ray structure. The best agreement has been attained by including the surrounding protein in the calculations using the two-layer ONIOM (B3LYP:Amber) approach. The results presented in this study conclusively demonstrate the importance of the protein/active-site interaction on the active-site structure of the enzyme. The present theoretical study represents the largest system studied at the ONIOM level to date, containing 7992 atoms, including 84 atoms in the QM region and rest in the MM region.     

OXIDATIVE COUPLING OF METHANE OVER Mn_2O_3-Na_2WO_4/SiO_2 CATALYST Ⅰ.CHARACTERIZATION OF ACTIVE SITES ON THE CATALYST

EPR and Raman spectroscopy have been used to characterize the catalyst. F-centers with EPR parameter of g=2. 0046 form when gas phase oxygen is admitted onto the catalyst reduced with methane at 800℃- Molecular oxygen plays an induced role in the electron transfer from W4 to the oxygen ion vacancy which is produced by methane reduction. Raman spectra give the further evidence for the production of lattice oxygen from molecular oxygen.     

STUDIES OF MULTICOMPONENT COMPLEX OXIDE CATALYSTS FOR OXIDATIVE COUPLING OF METHANE VI.SURFACE BASICITY AND SURFACE ACTIVE OXYGEN SPECIES OF LiTi_xLa_(1-x)O_2 λ MULTICOMPONENT OXIDE CATALYSTS

The surface basicity of Ti-La-Li multicoinponent oxides has been investigated by means of CO2-TPD. The experiment results show that C2 (C2H6 C2H4) selectivity is related to surface basic strength. The surface active oxygen species have also been characterized by means of XPS, O2-TPD and so on. It has been indicated that C2 selectivity and CH4 conversion are correlated with lattice oxygen and the adsorbed oxygen on the surface of the catalyst respectively In the O2-TPD experiments, it has also been found that there are three kinds of oxygen species on the surface of the series catalvsts, which are a (100℃ 750℃) Among them α-oxvgen causes deep oxidation whileβand γ oxygen species are related to oxidalive coupling of methane (OCM).     

Nucleophilic aromatic substitution reactions of fluorobenzenechromium complexes with P-chiral secondary phosphine-boranes: synthesis of optically pure P-chiral (dialkyl)arylphosphine-boranes

Optically pure P-chiral (dialkyl)arylphosphine-boranes having high structural diversity were prepared by two- or three-component coupling of fluorobenzenechromium complexes, P-chiral secondary phosphine-boranes, and other nucleophiles. The stereochemical integrity at the P-stereogenic center was completely retained during the S_NAr process when the reaction was carried out in THF at low temperature.     

A New Convenient Method for the Resolution of 1, 1''''-Binaphthalene-2, 2''''-diol Via a Phosphite Using (-)-Menthol as Resolving Agent

Optically active 1,1-binaphthalene-2, 2-diol has become a quite important chiral source in different fields of chirotechnology, especially in asymmetric synthesis1. Its synthesis and resolution has been extensively studied and various resolution methods have been reported2. Among the reported resolution methods, the following three, namely, via the formation of phosphoric acid derivatives3, boric acid derivatives4 and inclusion complexes5, are the most important. OHOH+_( )-1(-)-(S)-1(+)-(R)…     

Synthesis of Naturally Occurring Pyrazine and Imidazole Alkaloids from Botryllus LeachiRID=”a”ID=”a”?Dedicated to Prof. G. M?rkl on the occasion of his 75th birthday

The synthesis of the naturally occurring and biologically active alkaloids 1 and 2, first isolated from the red ascidian Botryllus leachi by Duran et al. [1], is described and the structure proposed for Botryllazine B (1) is confirmed. The analytical data for 2-(p-hydroxybenzoyl)-4-(p-hydroxyphenyl)imidazole (2) are discussed and compared with the literature. With special emphasis of ¹H NMR data the tautomerism of aroylimidazolemethanones is described.     

微量元素活性剂口服液对中老年人血液脂蛋白和脂质过氧化反应的影响

30名受试者平均年龄59．5±6．9岁．其中女性11名。每名受试者连续饮用微量元素活性剂口服液1个月。结果表明．血清总胆固醇由6．037mmol／L减少到4.867mmol／L，P＜0.01。低密度脂蛋白由4.470mmol／L减少到3．667mmol／L．P＜0．O1．甘油三脂和极低密度脂蛋白也分别降低了9．8％和10．6％；而高密度脂蛋白由0.720mmol／L增至1．003mmol／L，P＜O．O5；血浆丙二醛浓度由4．435mmol／L降至4.081mmol／L，P＜0．05：红细胞谷胱甘肽过氧化物酶和超氧化物歧化酶浓度均升高。血脂和血脂蛋白的变化表明．微量元素活性剂口服液对中老年人防治脑动脉硬化和冠心病具有良好作用。     

The application of levulinic acid and 5-nitro-2-furylmethylene diacetate in the total synthesis of some novel biologically active (5-nitro-2-furyl)azomethines

Summary The syntheses andin vitro antibacterial and antifungal evaluation of certain (5-nitro-2-furyl)azomethines with different heterocyclic nuclei are described.

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Die Anwendung von Lävulinsäure und 5-Nitro-2-furylmethylendiacetat in der Totalsynthese einiger neuer biologisch aktiver (5-Nitro-2-furyl)azomethine

Zusammenfassung Es wird die Synthese und diein-vitro-antibakterielle und antifungale Wirksamkeit für bestimmte (5-Nitro-2-furyl)azomethine mit verschiedenen heterocyclischen Kernen beschrieben.

     

Controlled-rate thermal analysis

Controlled-rate thermal analysis (CRTA) and differential scanning calorimetry (DSC) were used to investigate the adsorbed water layers and the surface properties of different commercial activated carbons. A simple method is proposed to obtain information on the properties of the adsorbed water film and the surface heterogeneity of the materials studied. This method utilizes TG mass loss and the first derivative of the DTG mass loss curves with respect to temperature and time, obtained during programmed liquid thermodesorption. The obtained TG mass loss curves, which reflect the energetic heterogeneity, consisted of steps and inflections which were associated with the mechanism of wetting of the solid surfaces. The heights of these steps and inflections depend on the adsorption capacity, the adsorption potential and the nature and number of the active centers of the carbon samples studied. The values of the total porosity and the surface phase capacity obtained by this method are in good agreement with those estimated on the basis of independent methods. The behaviour of water/carbon samples was studied by means of DSC at subambient and elevated temperatures. The experimental results provided novel data on the structural heterogeneity, the thermal stability of the water/carbon interface and its phase and structural transitions.Support from the Research Council of Kent State University (Ohio, USA) is acknowledged. The author is pleased to thank Drs M. Jaroniec, R. K. Gilpin, J. Choma and R. Dobrowolski for fruitful discussions and the active carbon samples.