Surface diffusion of metal atoms on polymer substrates during physical vapour deposition

 The surface diffusion of physical-vapour-deposited metal atoms on thermoplastic polymer substrates was investigated. In accordance with the hypothesis of the “classical” atomistic diffusion model, diffusion coefficients are derived from a Monte Carlo simulation. Because the “classical” atomistic diffusion model neglects the desorption of the metal atoms, the absolute diffusion data obtained in our investigations should only be considered as rough estimates. It is more the intention of our work to present relative values in order to correlate the metal surface diffusion on polymer substrates with their physical states (morphologies and surface dynamics). As expected, the diffusivity of metal atoms is strongly influenced by the chemical affinity (“reactivity”) between the metal atoms and the polymer substrate. Furthermore, the diffusivity strongly depends on the physical state of the polymer substrate. On polymer surfaces above the glass-transition temperature the surface diffusivity of metal atoms is 1 order of magnitude higher than the diffusivity below the glass-transition temperature. Received: 9 April 1999/Accepted in revised form: 21 October 1999     

Liquid fluidized bed starter culture ofTrichoderma reesei for cellulase production

A starter culture ofTrichoderma reesei (Rut-C30) prepared in a liquid fluidized bed reactor (LFBR) gave better growth and greater cellulase production in submerged fermentation than a conventional shake flask inoculum. The LFBR starter was prepared by first coatingT. reesei spores to 0.25 mm size corncob (1.0x10⁸g^-1) in a medium containing 1.0% corncob, 0.5 gL^-1 xylose and 0.1 gL^-1 lactose in a balanced salt solution, then fluidizing the particles in the LFBR for 36 h to allow germination of the spores, and covering the particles with an approx 30 μm thick biofilm. This biofilm that developed in constant adherence to the lignocellulosic carrier, apparently became well adapted to grow rapidly on insoluble cellulose substrates (Solca Floc), and had the enzymes of the cellulase complex induced for increased cellulase production. The LFBR starter used in a stirred tank reactor (STR) gave 15 gL^-1 biomass production and 6.5 IU mL^-1 overall cellulase activity with a volumetric productivity of 64 IU L^-1h^-1 in a 5 d fermentation, compared with a 7 d shake flask inoculum that gave 11 gL^-1 biomass and 3.2 IU mL^-1 cellulase activity, with a volumetric productivity of 31IU L^-1h^-1. The LFBR starter culture retained its viability in dry storage for 6–9 mo.     

Ascorbate oxidase

Ascorbate oxidase fromCucurbita sp. was isolated by ammonium sulfate precipitation and DEAE-dextran-silochrome column chromatography. The thermal and pH stabilities of the purified enzyme were investigated. TheK _M forl-ascorbic acid (1.5 mM) and chlorohydroquinone (0.37 mM) was determined. Substrate specificity of ascorbate oxidase was investigated and compared with those of laccases fromCoriolus hirsutus andCerrena maxima. Ascorbate oxidase was covalently bound to a polymeric membrane and used in an enzyme electrode for ascorbic acid.     

W／O型微乳液中超氧化物阴离子的产生——微环境中SOD酶活性测定方法 …

分别在水溶液中和W／O型CTAB／正戊醇／异辛烷／水微乳液体系中研究了测定SOD酶活性的邻苯三酚法,发现在反向微乳液中,"小水池"的低介电常数和pH抑制了底物超氧化物阴离子O2-·的产生．只有提高外加缓冲液的pH或"小水池"的水化度,才能得到所需浓度的O2-·,从而初步解决了在微乳液中SOD作用底物的产生问题,为在微乳液中准确测定SOD酶活性创造了条件．     

尿激酶活性测定方法的比较

根据中国及日本药典,对测定尿激酶活性的两种方法的灵敏度和重复性进行了考察对比,对不同样品测定结果进行了比较。     

New paradigms for synthetic pathways inspired by bioorganometallic chemistry

Two series of particular examples of reactions used in bioorganometallic chemistry are described. One based on a decomplexation-complexation reaction, indicates how, starting from a cymantrenyl derivative, a range of organometallic complexes bearing various metals can be prepared. The second one refers to the easy synthesis in water of the very versatile Alberto's reagent, which leads to new organometallic radiopharmaceuticals of Tc and Re.     

Organoelement Compounds with Al?Al,Ga?Ga,and In?In Bonds

In the attempt to synthesize compounds with aluminum in a low oxidation state and an Al Al bond, by the reduction of alkylaluminum halides with alkali metals, analogous to a Wurtz coupling, in general the deposition of elemental aluminum and the formation of the corresponding trialkylaluminum compounds is observed. Thus, tetrasubstituted dialuminum compounds R₂Al AlR₂, apart from a few poorly characterized examples, were for a long time considered part of an unverified class of substances. Only with the sterically very highly shielded tetrakis[bis(trimethylsilyl)methyl]dialuminum did we achieve the synthesis of the first completely characterized organoelement compound with unlimited stability, which shows aluminum in the oxidation state + II and has an Al Al bond. In the meantime, corresponding compounds for the elements gallium and indium have been obtained. With the simple access to tetrasubstituted dimetal compounds, a fascinating new research area has opened for preparative chemistry, in which the particular interest will naturally lie in the reactive properties of the metal-metal bond.     

引发甲基丙烯酸甲酯聚合的聚丙烯酰胺－氯化铜配合物膜催化剂表征

考察甲基丙烯酸甲酯在室温Ｎａ２ＳＯ３水溶液的聚合能力，发现在该溶液添加聚丙烯酰胺（ＰＡＡｍ）－氯化铜（ＣｕＣｌ２）配合物膜以组成ＰＡＡｍ－ＣｕＣｌ２膜／Ｎａ２ＳＯ３催化引发体系是必不可少的．采用ＥＳＲ、ＩＲ、ＸＰＳ和电导率等手段研究该体系催化剂的表面结构．结果表明，膜的单位面积平均含铜量在一定范围内和配位体种类等对催化活性有显著影响，即催化性能与催化剂的表面结构紧密相关．     

The use of a radiation inactivation method for characterization of the structure and catalytic properties of enzymes

The use of a radiation inactivation method for studies of the properties of enzymes of different classes is discussed. The possibilities of characterization of enzymes on the basis of the radiation-chemical parameters concerned are described.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No, 12, pp. 2828–2836, December, 1996.