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991.
Paul Dalhaimer Harry Bermudez Dennis E. Discher 《Journal of Polymer Science.Polymer Physics》2004,42(1):168-176
Giant and stable wormlike micelles formed in water from a series of poly(ethylene oxide) (PEO)-based diblock copolymer amphiphiles mimicked the flexibility of various cytoskeletal filaments. The worm diameter (d) was found by cryo-transmission electron microscopy to scale with the length of the hydrophobic chain (Nh) of the copolymer as d ∼ Nh0.61. By fluorescence video imaging of worm dynamics, we also showed that the persistence length (lP) of wormlike micelles scaled as lP ∼ d2.8, consistent with a fluid aggregate (∼d3) rather than a solid rod (∼d4). By polymerizing the unsaturated bonds of assembled copolymers, fluid worms were converted to solid-core worms, extending the bending rigidity from that of intermediate filament biopolymers to actin filaments and, in principle, microtubules. Through partial crosslinking, polymerized worms further locked in spontaneous curvature at a novel fluid-to-solid percolation point. The dynamics of distinct, branched conformations were also imaged for recently discovered Y-junctioned wormlike micelles composed of diblocks of high molecular weight (>10–15 kg/mol). Finally, block copolymers of hydrophilic weight fraction close to the transition between a vesicle- and worm-former assembled into both structures, allowing encapsulation of wormlike micelles in giant vesicles reminiscent of cytoskeletal filaments enclosed within cells. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 168–176, 2004 相似文献
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The source of a rate retardation of the trimethylsilyl substituent in an alkylation reaction is probed. 相似文献
995.
Dennis Dieks 《Foundations of Physics Letters》1990,3(4):347-357
When a quantummechanical wavepacket undergoes a series of Galilean boosts, the Schrödinger theory predicts the occurrence of a geometrical phase effect that is an example of Berry's phase (Sagnac's phase). In the present paper the conceptual consequences of this phenomenon are considered, in particular for the status of Galilean invariance in nonrelativistic quantum mechanics, and for the relation between that theory and classical physics. 相似文献
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997.
Dennis Piet Serge De Bruijn Jane Sum Gerrit Lodder 《Journal of heterocyclic chemistry》2005,42(2):227-231
The intermolecular meta photocycloaddition of 1,3‐dihydroisobenzofuran and 1,3‐dihydroisoindole‐2‐carboxylic acid methyl ester with cyclopentene and 2,5‐dihydrofuran affords two new classes of photoadducts. The photoadducts were identified by the SORT&gen algorithm as New Molecular Entities in two‐dimensional scaffold space. The structures of the adducts were established by NMR spectroscopy and the stereo‐, regio‐ and chemoselectivity of the reactions is discussed. 相似文献
998.
Dennis F Karney 《Advances in Applied Mathematics》1981,2(1):7-12
In 1961, Clark proved that if either the feasible region of a linear program or its dual is nonempty and bounded, then the other is unbounded. Recently, Duffin has extended this result to a convex program and its Lagrangian dual. Moreover, Duffin showed that under this boundedness assumption there is no duality gap. The purpose of this paper is to extend Duffin's results to semi-infinite programs. 相似文献
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