谷氨酸钠流化床吸附脱色的柱过程研究

以颗粒活性炭(GAC)为吸附剂,采用多柱串联流化床进行味精中和液脱色,对柱过程进行了模拟研究。测定了平衡数据、传质动力学及流体流动参数,建立了具有广泛适应性的,包括颗粒分级、粒度分布、内外扩散及两相返混的宽粒度液固流化床吸附过程模型。对所研究体系的模拟计算与实验结果符合较好。     

感染日本血吸虫小鼠心房特殊颗粒的形态学观察和定量分析

小鼠感染日本血吸虫尾蚴后第２８天,右心耳心房特殊颗粒数目显著减少,且多见膜溶解、断裂,半月形排空和颗粒膜与横管膜及肌膜靠近、融合及颗粒向横管腔及肌膜下突出的现象。心肌细胞内线粒体有肿胀、基质变浅及部分嵴断裂现象。感染组小鼠右心耳心房特殊颗粒的体密度（０．０３２３±０．００２９μｍ３／μｍ３）、面数密度（０．８６４７±０．０６９２μｍ－２）、数密度（３．２３６３±０．１１１４μｍ－３）及颗粒平均直径（０．２６７１±０．０２０７μｍ）均显著小于对照组的０．０９７１±０．０１２７μｍ３／μｍ３、１．９２１±０．１１４５μｍ－２、０．２１８９±０．０８６６μｍ－３和０．３１０８±０．０１９５μｍ。本文阐述了日本血吸虫感染后,促进心房特殊颗粒释放增加。     

Altering coenzyme specificity of <Emphasis Type="Italic">Pichia stipitis</Emphasis> xylose reductase by the semi-rational approach CASTing

Background  

The NAD(P)H-dependent Pichia stipitis xylose reductase (PsXR) is one of the key enzymes for xylose fermentation, and has been cloned into the commonly used ethanol-producing yeast Saccharomyces cerevisiae. In order to eliminate the redox imbalance resulting from the preference of this enzyme toward NADPH, efforts have been made to alter the coenzyme specificity of PsXR by site-directed mutagenesis, with limited success. Given the industrial importance of PsXR, it is of interest to investigate further ways to create mutants of PsXR that prefers NADH rather than NADPH, by the alternative directed evolution approach.     

An evolved xylose transporter from Zymomonas mobilis enhances sugar transport in Escherichia coli

Background  

Xylose is a second most abundant sugar component of lignocellulose besides glucose. Efficient fermentation of xylose is important for the economics of biomass-based biorefineries. However, sugar mixtures are sequentially consumed in xylose co-fermentation with glucose due to carbon catabolite repression (CCR) in microorganisms. As xylose transmembrance transport is one of the steps repressed by CCR, it is therefore of interest to develop a transporter that is less sensitive to the glucose inhibition or CCR.     

Dominant Gene cplsr1 Corresponding to Premature Leaf Senescence Resistance in Cotton (Gossypium hirsutum L.)

Cotton (Gossypium hirsutum L.) premature leaf senescence-resistant inbred XLZ33 and senescencesusceptible inbred lines XLZ13 were selected and crossed to produce F1,F1-reciprocal,F2 and BC1 generations...     

不同刈割强度对牧草地上部和地下部生长性状的影响

研究了不同刈割强度对牧草地上部和地下部生长状况的影响.结果表明,适度刈割可提高牧草地上部植株的再生能力.刈割后牧草再生叶片的叶绿素总量变化不大,而叶绿素a/b比值有所增加,轻刈割和重刈割的牧草叶绿素a/b比值分别增至1.59∶1和1.52∶1、不刈割为1.22∶1,有利于增强植物的光合作用.与不刈割处理相比,在刈割初期,重刈割处理下柱花草根系总长、总表面积和平均直径分别下降了54.9%、66.5%和27.2%,根系活力显著下降;但在中后期,刈割处理的牧草地下部根系形态指标活力可恢复到更高的水平.从一年两次收获的累计生物量来看,以轻刈割最高,为3 179.8 g·m^-2,重刈割次之,为3 006.1 g·m^-2,不刈割最低,为2 936.98 g·m^-2,说明一年两次刈割可以提高牧草产量.     

利用乳化液膜分离丙氨酸的研究

对乳化液膜技术分离丙氨酸进行了实验研究,从而探索了从味精生产过程的。第二次等电点结晶母液”中回收丙氨酸的新途径。采用二(2-乙基已基)磷酸为载体和表面活性剂失水山梨醇单油酸酯、磺化煤油组成液膜体系。研究了影响乳化液膜提取的各种因素,确定了适宜的分离条件。丙氨酸的单级提取率超过60％,浓缩3倍以上。对该液膜体系在交流高压静电场作用下,箱式破乳器的破乳过程,建立了破乳速率和相关操作因素间的定量关系。