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The interfacial compatibility of composite membrane is an important factor to its structural stability, andseparation performance. In this study, poly (ether sulfone) (PES) support layer was first hydrophilically modified with poly(vinyl alcohol) (PVA) via surface segregation during the phase inversion process. Gelatin (GE) was then cast on the PVA-modified PES support layer as the active layer followed by crosslinking to fabricate composite membranes for ethanol dehydration. The enrichment of PVA on the surface of support layer improved interfacial compatibility of the as-prepared GE/PVA-PES composite membrane. The water contact angle measurement and X-ray photoelectron spectroscopy (XPS) data confirmed the surface segregation of PVA with a surface coverage density of -80%. T-peel test showed that the maxima/force to separate the support layer and the active layer was enhanced by 3 times compared with the GE/PES membrane. The effects of PVA content in the support layer, crosslinking of GE active layer and operating parameters on the pervaporative dehydration performance were investigated. The operational stability of the composite membrane was tested by immersing the membrane in ethanol aqueous solution for a period of time. Stable pervaporation performance for dehydration of 90% ethanol solution was obtained for GE/PVA-PES membrane with a separation factor of -60 and a permeation flux of -1910 g.m^-2.h1 without peeling over 28 days immersion. 相似文献
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为了适应多媒体技术的发展,国际标准化组织(ISO)制定了新一代的静止图像压缩标准JPEG2000。本文介绍了该标准产生的背景及其要达到的目的。详细论述了该标准体系结构的各组成部分及关键技术。最后举例说明了它的应用前景。 相似文献
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以甜菜红苷(Bt)为对象,采用-荧光光谱、傅里叶变换红外光谱以及圆二色谱技术分析乳清蛋白(WP)和牛血清白蛋白(BSA)与Bt作用生成的复合物中乳蛋白组分对Bt热稳定性的影响。结果表明:添加WP和BSA能有效抑制甜菜红苷的热降解作用,其中WP对甜菜红苷的保护作用优于BSA。同时,体系环境的pH值变化也明显影响甜菜红苷的热降解,在pH 5.0时甜菜红苷复合物的半衰期最长,其中Bt-WP复合物的半衰期达2.99 h。荧光光谱、傅里叶变换红外光谱以及圆二色谱分析表明,复合物中Bt组分的作用导致WP和BSA发生静态荧光猝灭,WP和BSA色氨酸残基和酪氨酸残基所处微环境的疏水性减弱,极性变强。此外,添加Bt使两种蛋白质的构象结构发生改变,酰胺Ι带和酰胺Ⅱ带的特征峰位置改变,二级结构中各类构象组成发生不同程度的变化。 相似文献
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芦霞 《河南机电高等专科学校学报》2011,19(4):86-89
对某高校大学生的职业决策困难状况以及归因风格对他们职业决策困难的影响进行了研究。结果表明:大学生职业决策困难的总体水平不是很高;大学生的职业决策困难程度呈现出性别、年级、专业、是否接受就业指导训练的群体差异;归因风格类型对职业决策困难的不确定性维度、自我认知维度、职业目标维度、职业自我探索维度和社会支持维度的影响差异显... 相似文献