Influences Of Precursor Constitution And Processing Speed On Microstructure And Wear Behavior During Laser Clad Composite Coatings On Gamma-Tial Intermetallic Alloy

The effects of constitution of precursor mixed powders and scan speed on microstructure and wear properties were designed and investigated during laser clad gamma/Cr7C3/TiC composite coatings on gamma-TiAl intermetallic alloy substrates with NiCr-Cr3C2 precursor mixed powders. The results indicate that both the constitution of the precursor mixed powders and the beam scan rate have remarkable influence on microstructure and attendant hardness as well as wear resistance of the formed composite coatings. The wear mechanisms of the original TiAl alloy and laser clad composite coatings were investigated. The composite coating with an optimum compromise between constitution of NiCr-Cr3C2 precursor mixed powders as well as being processed under moderate scan speed exhibits the best wear resistance under dry sliding wear test conditions. (C) 2008 Elsevier Ltd. All rights reserved.

Purification and characterization of a new L-amino acid oxidase from Daboia russellii siamensis venom

A new L-amino acid oxidase (designated as DRS-LAAO) was purified from Daboia russellii siamensis venom by ion-exchange, gel filtration and affinity chromatographies. DRS-LAAO is a homodimeric enzyme with a molecular weight of 120.0 kDa as measured by size

Purif ication and Characterization of Jerdonitin ,a Non2hemorrhagic Metalloproteinase fromTrimeresurus jerdonii Venom

以前从菜花烙铁头蛇毒中分离纯化到J erdonitin 。与其他Ⅱ型蛇毒金属蛋白酶相比, J erdonitin 由金属蛋白酶和去整合素两个结构域组成。但没有检测到其出血和纤维蛋白原降解活性, 推测可能高压液相色谱的有机溶液影响了其酶活性。采用不含高压液相色谱柱层析的新分离手段分离得到J erdonitin 。J erdonitin 在还原和非还原SDS2PAGE 电泳中分别呈现一条表观分子量为38 和36 kDa 的条带。像其他典型的蛇毒金属蛋白酶一样, J erdonitin 优先降解人纤维蛋白原的alpha 链, 并且该活性能被EDTA 完全抑制, 而PMSF 对其没有影响。J er2 donitin 不诱导小白鼠皮下出血。