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951.
952.
William T. Murray Anne Pautard-cooper Nita A. Eskew Slayton A. Evans Jr 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):101-104
Abstract The kinetics of Lewis acid-mediated decomposition and definitions of the synthetic applicability of 1,3,2λ5-dioxaphospholanes for (i) the syntheses of highly-hindered epoxides, and (ii) the stereospecific functionalizations of stereocenters in 1,2-diol arrays are described. 相似文献
953.
954.
Stephen L. De Wall Eric S. Meadows Clare L. Murray Hossein Shabany George W. Gokel 《Supramolecular chemistry》2013,25(1):13-22
Abstract A family of tris(macrocyclic) compounds of the form sidearm<N18N>Cn<N18N>Cn<N18N>sidearm, has been prepared, characterized chemically, and assayed by dynamic 23Na-NMR for the ability to transport sodium cations in a mixed phosphatidylglycerol/phosphatidylcholine vesicle system. A number of control experiments have been conducted that reinforce the hypothesis that cation transport occurs by a channel mechanism. The tris(macrocycle) channels proved to be functional at a level of 25–50% of that found for the natural pentadecapeptide channel gramicidin. Fluorescence data confirm the expected position of the channel within the bilayer. 相似文献
955.
956.
957.
Mass spectrometry (MS) analysis, after enzymatic or chemical deglycosylation, requires preparatory steps to remove salts and buffers. In this work, the glycosylated protein fetuin and a lectin protein isolated from the serum of Alligator mississippiensis were used to evaluate methods for desalting samples after an enzymatic or chemical deglycosylation. Precipitation and dialysis were used to prepare the deglycosylated samples for MS analysis. Both the precipitation and dialysis methods were suitable for sample preparation prior to analysis by matrix assisted laser desorption ionization (MALDI) MS. 相似文献
958.
Stephen F. Bartolucci Karen E. Supan Jeffrey S. Wiggins Lawrence LaBeaud Jeffrey M. Warrender 《Polymer Degradation and Stability》2013
Polypropylene based nanocomposites filled with montmorillonite nanoclay prepared by twin screw extrusion have been studied for thermal stability at high heating rates. In contrast to traditional thermal stability and flammability studies of polymer nanocomposites using heating rates on the order of tens of degrees per minute, this study achieves heating rates that are six orders of magnitude higher. This was accomplished using laser pulse heating. The results show that the nanoclay increases thermal stability of the polymer, as measured by a decrease in the mass loss for a laser pulse at a given energy and intensity. Electron microscopy and various spectroscopic techniques show that a silicate-rich char layer may provide the mechanism for protection of the polymer and decreased degradation rates. The results of the study are compared to the typical results found in traditional thermal stability testing. 相似文献
959.
960.
Michael A. Drahl Prof. Madhuri Manpadi Prof. Lawrence J. Williams 《Angewandte Chemie (International ed. in English)》2013,52(43):11222-11251
It has been 60 years since Eschenmoser and Frey disclosed the archetypal C? C fragmentation reaction. New fragmentations and several variants of the original quickly followed. Many of these variations, which include the Beckmann, Grob, Wharton, Marshall, and Eschenmoser–Tanabe fragmentations, have been reviewed over the intervening years. A close examination of the origins of fragmentation has not been described. Recently, useful new methods have flourished, particularly fragmentations that give alkynes and allenes, and such reactions have been applied to a range of complex motifs and natural products. This Review traces the origins of fragmentation reactions and provides a summary of the methods, applications, and new insights of heterolytic C? C fragmentation reactions advanced over the last 20 years. 相似文献