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91.
用四种修饰纤维素酶Cell-MAL(5,10,20 K)和Cell-SPA 5 K和天然纤维素酶在p H=13.63,T=45℃反应时间为1 h的7%(wt)Na OH/12%(wt)尿素溶液中降解羧甲基纤维素。得到四种修饰纤维素酶的活性均比天然纤维素酶的活性高。其中Cell-MAL 5 K的活性最高。然后浓度分别为1/100、1/300、1/500和1/700的7%(wt)Na OH/12%(wt)尿素水溶液中分别测定了天然纤维素酶和四种修饰纤维素酶的米氏常数分别为2.853、1.735、1.777、4.622和10.01 mg/L。 相似文献
92.
J. Clifford Jones 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1996,65(2):176-178
Previously presented ignition data for raw cotton are used in order to make predictions of hazards from hot particle entry into a previously thermally quiescent cotton bale. The calculations make use of a numerical approach to ignition by a heat source. 相似文献
93.
Haem derived from animal blood is a valuable source of organic iron which may be used as a supplement in foods. The purpose of this study was to examine the effects of sodium carboxymethyl cellulose (NaCMC), propylene glycol alginate (PGA) and sodium alginate (SA) as viscosity enhancers on the separation of haem from porcine red blood cells, and on the distribution of iron between the haem and non-haem fractions of the extracts. Iron determinations were carried out spectrophotometrically on the supernatants obtained by centrifuging the cell suspensions and on two successive washings of the cells. In the first washings the total extracted iron content using NaCMC was highest when a high-viscosity grade was used; there were no significant differences (P>0·05) between the results obtained with this material and those obtained using PGA or SA. There were also no significant differences (P>0·05) among the three treatments in terms of non-haem content. The absorbances at 540nm of the first washings were lower when the washing was carried out at pH 1·4 rather than at pH 1·0 or 2·0. There were no significant differences associated with changes in the viscosity enhancer in the absorbances of the second washings, but the absorbances at pH 1·4 were generally higher than those at pH 1·0 or 2·0. Enhancement of the absorbances on the addition of 1,10-o-phenanthroline indicated that the extracted iron was present in the ferrous form. 相似文献
94.
In this study, we compare the effect of twin-screw extrusion processing on the attrition of wood fibers (WFs) with glass fiber. The effects of process variables and screw design on fiber length were investigated by performing a range of dead-stop experiments where the extruder was stopped, opened-up, and compound removed from the screw elements. Fibers, chemically extracted from the polypropylene matrix, were analyzed for length and width using a commercial fiber analyzer. It was found that WF length attrition and composite properties were less affected by screw design and twin-screw processing conditions (feed rate and screw speed) than glass fiber. Length weighted fiber length and X50 length (a measure used in particle size analysis) were equally correlated with process conditions and composite performance for both fiber types. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48551. 相似文献
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鱼油脂肪酸乙酯化工艺研究 总被引:11,自引:0,他引:11
比较三种不同鱼油原料脂肪酸组成、含量和各项品质指标,选取步鱼油用碱催化法进行乙酯化反应。通过单因素实验和响应面分析,步鱼油乙酯化工艺最优条件为:无水乙醇/鱼油反应物摩尔比为6:1,反应温度为75℃~77℃,反应时间2小时,碱催化剂浓度为0.8N~1.0N,由分子蒸馏得到乙酯化得率为96%。 相似文献
98.
Effect of ‘wheat Qu’ addition on the formation of ethyl carbamate in Chinese rice wine with enzymatic extrusion liquefaction pretreatment 下载免费PDF全文
Enbo Xu Zhengzong Wu Fang Wang Jie Long Xueming Xu Zhengyu Jin Aiquan Jiao 《Journal of the Institute of Brewing》2016,122(1):55-62
Ethyl carbamate (EC), which has been confirmed as probably carcinogenic to humans, can be formed during the alcoholic fermentation of Chinese rice wine. In this study, EC and two possible precursors (urea and arginine) were analysed in wines fermented from rice processed by enzymatic extrusion liquefaction pretreatment, with different wheat Qu content gradients from 6 to 18% (dry basis, d.b.). The EC concentration decreased 22.5% with the addition of wheat Qu reduced to 6% for the enzymatic extrusion‐processed rice wine (EE). Moreover, although the arginine was generated 6.33–8.39 times higher in the enzymatic extruded rice, instead of the traditional treated rice at the same wheat Qu level, the corresponding level of urea formed from arginine was not high in the EE. In addition, rice treated by extrusion combined with enzymatic hydrolysis was found to be more utilizable and fermentable, and the lost quality of the final traditional rice wine with the low wheat Qu level (6–14%) could be improved using enzymatically extruded rice as the fermenting material. Therefore, it may be feasible to inhibit EC accumulation in Chinese rice wine by wheat Qu control, combined with enzymatic extrusion pretreatment for rice. Copyright © 2015 The Institute of Brewing & Distilling 相似文献
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In the common woodlouse Porcellio scaber different parts of the gut were observed with respect to microbial counts, cellulose activity, and degradation of cellulose. Cellulose is mainly digested in the anterior part of the hindgut, as was indicated by the distribution of cellulolytic activity and the decrease of cellulose content inside the gut. The cellulases woodlice utilize for the degradation of litter are mainly produced by endosymbiotic bacteria in the hepatopancreas rather than by microorganisms ingested with the food. Microorganisms ingested with the litter are digested in the anterior part of the hindgut and may provide an important food source. In the posterior hindgut, bacterial proliferation ensures microbial colonization of feces. 相似文献