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71.
Martine Decloux Manuel Dornier & Isabelle Gratius 《International Journal of Food Science & Technology》1996,31(2):153-166
Gum arabic is a natural gum exuded mainly by the trees Acacia senegal , currently used in the food industries for its emulsifying, thickening and stabilizing properties. Its present processing includes various operations providing a quite turbid product. Crossflow microfiltration could be interesting for the clarification and the cold-pasteurization of the gum arabic solutions. Several experiments were therefore made with the crossflow microfiltration unit at ENSIA, using two different systems: the classical one (without permeate circulation), and the co-current permeate flow system (CCPF) allowing the exploration of the low transmembrane pressures range. With gum arabic solutions of 0.17g solids g−1 solution and 70°C, the best results after 60 min of filtration (105.7 L h−1 m−2 , 4.4% of solids retention and 83.4% of clarification) were obtained with the CCPF system at low transmembrane pressure and high crossflow velocity (0.3 bar and 7.5ms−1 ). 相似文献
72.
本文介绍核孔膜生产线,重点描述了膜微孔制备工艺的实验研究。对于PC和PES膜,已得到32种工况下的扩孔公式,其形式为D=A+Bt,其中D——孔径,t——扩孔时间,A,B为特定工艺参数下的常数值.通过实验。得到了膜孔密度N与300~#核反应堆功率P、热柱辐照位置L的经验公式,即N=6.97×10~5×10~3×101~(1.18L).在本生产线上可生产最大幅面为3 140mm×240mm,孔径为0.04~10 μm的多系列多规格的核孔膜产品。 相似文献
73.
The effect of antioxidants contained in poly(ethylene glycol) (PEG) on cell fusion was studied using L929 cells in the monolayer state. Hydroquinone monomethyl ether (HQME), 2-mercaptobenzimidazole (MB), butyl hydroxyanisole (BHA) and 2,6-di-(t-butyl)-4-methylphenol (BHT) were chosen from the antioxidants that have currently been used to protect commercially available PEG from oxidation. Cell culture was conducted in 40% w/w aqueous solution of PEG with a molecular weight of 3000 in the presence of different concentrations of antioxidants. BHA clearly enhanced membrane fusion of L929 cells with increasing concentration in PEG solution, whereas HQME, MB and BHT had no significant effect on cell fusion. The enhancement of cell fusion by BHA might be ascribed to balanced hydrophobicity and high water solubility in comparison with the other three antioxidants. 相似文献
74.
The hydrodynamic characteristics and mass transfers of halide quaternary salts between two immiscible phases in a stirred membrane permeation cell were investigated. The concentration of quaternary salt, temperature, solvent and the four kinds of halide quaternary salts were evaluated to achieve the extractive optimum condition. The diffusivity, overall mass‐transfer coefficients and individual mass‐transfer coefficients were determined and correlated in terms of the conventional Sh‐Re‐Sc relationship. The transfer time of quaternary salts across the membrane and the thickness of the hydrodynamic diffusion boundary layer were determined as well, so as to characterize the extractive phenomenon of quaternary salts between the two phases that is useful in phase‐transfer catalysis. 相似文献
75.
P. Bocchetta C. Sunseri A. Bottino G. Capannelli G. Chiavarotti S. Piazza F. Di Quarto 《Journal of Applied Electrochemistry》2002,32(9):977-985
Alumina membranes were fabricated by anodizing aluminium metal in 0.15 M oxalic acid. The growth kinetics of the porous layer were investigated in the temperature range –1 to 16 °C using linear potential scans up to 70 V. The faradaic efficiencies of metal oxidation and of porous layer formation, determined by applying Faraday's law, were found to be independent of both temperature and electrical charge. SEM analysis of the metal-side and solution-side surfaces revealed different morphologies. After dissolution of the barrier layer in phosphoric acid, the metal-side surface showed circular pores whose size of about 90 nm was found to be uniform and independent of temperature. The pore population was also practically independent of temperature and a value of about 4 × 1013 pores m–2 was determined. On the solution-side surface the presence of a deposit partially occluding the mouths of pores was observed. This coating could be removed by chemical etching in NaOH or thermal treatment at 870 °C, where decomposition of oxalate occurs. This supports the hypothesis that the deposit consists of an aluminium salt containing oxalate anions precipitated from the solution. The results show that it is possible to control the morphological characteristics of the anodic alumina membranes by careful choice of experimental conditions. 相似文献
76.
77.
78.
Sei-Ichi Aiba Masato Izume Norihiko Minoura Yukihiko Fujiwara 《Polymer International》1985,17(1):38-40
Chitin membrane was prepared by casting a N,N-dimethyl acetamide, N-methyl 2-pyrrolidone and lithium chloride (DMA-NMP-LiCl)solution of chitin and coagulating with several media. The effect of the coagulants on membrane formation was studied. 2-Propanol was found to be more favourable than methanol, ethanol, acetone and mixtures of 2-propanol and water. The membrane obtained in 2-propanol was subjected to annealing. Annealing made the membrane dense and strong. The tensile strength of the membrane annealed at 145°C for 2hr was about twice that of an unannealed membrane. The solute permeability of the annealed membranes was lower than that of the original one. These phenomena could be clearly interpreted in terms of crystallinity. 相似文献
79.
80.
将LambdaDNA引入活化的非洲爪蟾卵提取物中,在由磷酸肌酸与磷酸肌酸激酶构成的ATP再生系统的参与下,在这种非细胞体系中能够围绕由LambdaDNA诱导形成的染色质重建核被膜结构,同时在染色质外出现类似核被膜结构的环形片层。在这两种膜结构中核孔复合体的形成都与直径200nm左右的单层圆形小膜泡密切相关,这些小膜泡可以附着在染色质表面或独立于染色质之外相互融合成扁平囊状的双层膜片层,双层膜进一步融合形成核孔,与此同时,核孔复合体在核孔上完成装配。 相似文献