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991.
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993.
Iannucci NB Navarro del Cañizo AA Cascone O 《Applied biochemistry and biotechnology》2003,104(3):173-183
Twenty triazinic dyes were assayed as ligands for the chromatographic affinity purification of a neutral protease from Flavourzyme™, a commercial preparation. Screening at pH 4.0 allowed the selection of eight dyes on the basis of their high protease adsorption.
When the pH was set to 5.0 in order to increase selectivity, only Yellow HE-4R, Red HE-3B, and Cibacron Blue F3G-A maintained
protease adsorption at high values. Neither maximum capacities nor dissociation constants calculated from isotherms measured
at 8 and 25°C showed great differences. By contrast, a strong temperature effect was evidenced in the elution step: elution
at 8°C allowed 70, 81, and 98% recovery of adsorbed protease with Yellow HE-4R, Red HE-3B, and Cibacron Blue F3G-A, respectively,
whereas only 20% recovery was attained at 25°C. Based on the results obtained, a purification process for the neutral protease
contained in Flavourzyme with Cibacron Blue F3G-A as the affinity ligand was developed, yielding 96% of electrophoretically
pure enzyme in a single step, the specific activity rising from 850 to 3650 U/mg. 相似文献
994.
LeiLi Xiao-dongZhao Jing-lunZhou Xing-heFan Xiao-fangChen Xin-huaWan Qi-fengZhou 《高分子科学》2004,(4):349-353
Aromatic polybenzoxazole (PBO) precursor, hydroxy-substituted polyenaminonitrile, was prepared by direct polycondensation of 1,4-bis(l-chloro-2,2-dicyanovinyl)benzene (CCB) and 4,6-diaminoresorcinol dihydrochloride (DAR) using pyridine and N,N-dimethylacetamide as condensing agent and solvent. The precursor has good solubility in polar aprotic solvent which is due to the strong dipolar nature of the main chain. The soluble precursor was subjected to thermal cyclization in an inert atmosphere to convert it into the corresponding PBO, which has its 5% weight loss temperature at 540℃ The fully cyclized PBO were characterized by FT-IR and TGA. The introduction of 10% mol 1,3,5-benzenetricarboxylic chloride (BTC) into the main chain not only has little effect on the solubility of PBO precursor but also raises its 5% weight loss temperature to 552℃ and char yield at 700℃ for the cyclized PBO with BTC. 相似文献
995.
Xi-yan Liu Dong Qiu Mei-li Guo Zhen-zhong Yang 《高分子科学》2005,(5):561-566
Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples possessed one glass transition temperature (Tg) and two exothermal processes during DSC heating scannings. After being thermally treated above the exothermal peak temperature, they possessed two glass transition temperatures with the disappearance of exothermal peaks, whilst a core/shell structure was formed. This was likely related with the outward diffusion of reactive oligomers to the outer layer of particles. 相似文献
996.
997.
998.
Summary This research has demonstrated that the dielectric method can be used successfully for grain moisture measurements for diverse
grain types over wide ranges of temperatures if the grain moisture content is below certain (grain-specific) threshold values.
These high-moisture limits were estimated. Optimum temperature correction coefficients for 149 MHz moisture measurements were
determined for grain samples at different moisture levels. This information should be very helpful for grain moisture meter
manufacturers and for moisture meter users who need to determine grain moisture contents at temperature extremes to be able
to market grain more efficiently. 相似文献
999.
Grafting polymer glycols onto nano-silica surface through one-step procedure was investigated. The major characteristic of this procedure is that all the materials and reagents (silica, PEG, TDI, DBTDL, solvent) required for grafting were added simultaneously into the reaction vessel. TDI and DBTDL were used as coupling agent and catalyst, respectively.The products were characterized by FTIR, TGA, elemental analyses and TEM, giving evidence for successful grafting of PEG. Possible mechanism of this grafting was studied and two grafting processes were proposed. The process through which the grafting proceeds depends on the reaction temperature. Effect of molecular weight of PEG on grafting was also investigated. 相似文献
1000.