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491.
The objective of this research is to develop a relationship between salt type and concentration to poly(2-methacyloyloxyethyl
phosphorylcholine) (PMPC) zwitterionic polymer solution behaviors. In particular, polyelectrolyte hydrodynamic volumes were
analyzed through size exclusion chromatography in relation to the addition of various salts at various concentrations. The
salt properties examined were salt concentration, ionic strength, solution pH, cation type/size, anion type/size, valency,
and configuration. It was found that the effect of ion properties is related to mechanisms associated with the geometry of
the polyelectrolyte. The negative charge group of the polyelectrolyte situated closer to the backbone (inside) is less important
to the change in hydrodynamic volume than the positive charge group situated at the end of the side chain (outside). The extensive
amount of data generated in this study provides a strong background for possible accurate formulation of a theory based on
the salt effect on PMPC polyelectrolyte solution behavior. 相似文献
492.
Zhang Q Yu G Wang WJ Yuan H Li BG Zhu S 《Langmuir : the ACS journal of surfaces and colloids》2012,28(14):5940-5946
This work reports the development of a reversibly coagulatable and redispersible polystyrene latex system that can be triggered by N(2)/CO(2). The coagulatability and redispersibility of the latexes were achieved by employing 0.9-5.6 wt % (N-amidino)dodecyl acrylamide (DAm), a reactive switchable surfactant, in an emulsion polymerization of styrene under CO(2) atmosphere. The resulted latex particles were readily coagulated by N(2) bubbling at 60 °C and redispersed by CO(2) bubbling and ultrasonication, which switched amidine moieties between neutral and ionic states. The coagulation/redispersion processes were repeatable. The prepared latexes showed good stabilities against electrolytes, especially with higher charges. 相似文献
493.
A novel solution-processed, compositionally and structurally stable dual-layer gate dielectric composed of a UV-cured poly(4-vinyl phenol)-co-poly(methyl methacrylate) bottom layer and a thermally cross-linked poly(methyl silsesquioxane) top layer for organic thin-film transistors is described. This gate dielectric design, coupled with compatible solution-processable semiconductor and conductor materials, has enabled fabrication of all solution-processed, high-performance organic thin-film transistors on flexible substrates. High field-effect mobility and current on/off ratio, together with other desirable transistor properties, are demonstrated. 相似文献
494.
Changfeng Zhu Yanqin Wen Di Li Prof. Lihua Wang Prof. Shiping Song Prof. Chunhai Fan Prof. Itamar Willner Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(44):11898-11903
DNA replication plays a central role in living organisms. Unregulated or uncontrollable DNA replication is well known to result in many pathological states, such as cancer, autoimmune diseases, and viral/bacterial infections. We report that an aptamer–protein complex could indirectly inhibit in vitro replication of DNA. An isothermal DNA machine based on the strand‐displacement amplification is employed to support our assumption. An antithrombin aptamer sequence is rationally encoded into the DNA replication template. Once thrombin binds to the template, the as‐formed aptamer–protein complexes can, in turn, become a barrier to the polymerase and inhibit the DNA replication activities in both static and dynamic modes. The inhibition is successfully confirmed by both fluorescence and gel‐electrophoresis experiments. Considering the availability of a broad library of aptamers and the existence of various DNA/protein interactions, our results imply the possibility for the rational regulation of DNA replication in vivo. 相似文献
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In this paper we establish some new sufficient conditions on the existence of homoclinic solutions for a class of second-order Hamiltonian systems without a coercive potential. The proof is based on a new critical point theorem in combination with periodic approximation. 相似文献
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