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651.
Michael Bartke Sebastian Kröner Annette Wittebrock Karl-Heinz Reichert Ilias Illiopoulus Christoph Johannes Dittrich 《Macromolecular Symposia》2007,259(1):327-336
Summary: Sorption experiments of ethylene and propylene in different polypropylene powder samples, both homopolymer and heterophasic copolymers with different rubber content, have been carried out in a high-pressure magnetic suspension balance at 10 bars pressure and 70 °C. The gross solubilities measured can be well correlated with the rubber content of the polymer samples. Solubility of ethylene and propylene in the rubber phase differ from solubility in the amorphous fraction of the homopolymer, especially the concentration ratio of propylene to ethylene differs significantly between rubber phase and amorphous fraction of the homopolymer. From the slope of monomer uptake, information on kinetics of mass-transfer can be gained. No significant differences were observed in terms of mass-transfer for ethylene and propylene. With increasing rubber content, effective diffusion coefficients increased slightly. By combined sorption studies with powder samples and compressed films, information about both effective diffusion coefficients and the effective length scale of diffusion could be gained. It could be shown, that the particle radius is not the characteristic length of diffusion in the studied powder samples. Mass transfer of nearly all samples could be described by a constant diffusion length of 120 to 130 µm, independently on particle size. This indicates that the effective scale of diffusion in polymer particles is in between microparticle and macroparticle scale used in classical particle modeling. 相似文献
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Palma Marcia B. Pinto Annette L. Gombert Andreas K. Seitz Karina H. Kivatinitz Silvia C. Castilho Leda R. Freire Denise M. G. 《Applied biochemistry and biotechnology》2000,84(1-9):1137-1145
Lipase, protease, and amylase production by Penicillium restrictum in solid-state fermentation was investigated. The basal medium was an industrial waste of babassu oil (Orbignya oleifera) production. It was enriched with peptone, oliveoil, and Tween-80. The supplementation positively influenced both enzyme
production and fungal growth. Media enriched with Tween-80 provided the highest protease activity (8.6 U/g), whereas those
enriched with peptone and olive oil led to the highest lipase (27.8 U/g) and amylase (31.8 U/g) activities, respectively. 相似文献
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For finitep-groupsG we study the conjugation representation γG which is defined by lettingG act on itself by conjugation. Roth conjectured that every irreducible representation ofG which is trivial on the center ofG, occurs in γG. However, this is not true in general. We construct minimal counterexamples and verify Roth's conjecture for various classes
of finitep-groups, for instance those of maximal class.
Dedicated to Professor George Maltese on the occasion of his 60th birthday 相似文献
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Källström K Hedberg C Brandt P Bayer A Andersson PG 《Journal of the American Chemical Society》2004,126(44):14308-14309
A new class of chiral N,P-ligands for the Ir-catalyzed asymmetric hydrogenation of aryl alkenes has been developed. These new ligands proved to be highly efficient and tolerates a broad range of substrates. The enantiomeric excesses are in the range of the best ever reported. The results can be rationalized with the proposed selectivity model. 相似文献