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排序方式: 共有225条查询结果,搜索用时 46 毫秒
141.
R. N. Vannier R. J. Chater S. J. Skinner J. A. Kilner G. Mairesse 《Solid State Ionics》2003,160(3-4):327-334
Oxygen isotopic exchange has been studied for a number of materials in the BIMEVOX family of compounds. The exchanges were undertaken at 620 °C with gold grid electrodes on the samples and with a constant current flowing through the samples during the exchange anneals. These conditions simulate those used when these materials are employed in oxygen separation devices where substantial oxygen fluxes can be sustained using such simple gold grid electrodes.The results showed that samples exchanged under current flow conditions exhibit substantial oxygen exchange at the cathode, in contrast to samples where no electrical bias is applied. This effect was sustained in regions remote from the sputtered gold electrode. Complementary studies of the samples using X-ray diffraction revealed subtle changes in the diffraction patterns following experiments with current flow. These changes are ascribed to a reduction of V5+ to V4+ at the cathode locally transforming the BIMEVOX material into a mixed conducting material, and hence enhancing the oxygen isotopic exchange process. 相似文献
142.
J.M. Lavigne P. Jean B. Kandel V. Borrel J.P. Roques G. Lichti V. Schönfelder R. Diehl R. Georgii T. Kirchner Ph. Durouchoux B. Cordier N. Diallo F. Sanchez B. Payne P. Leleux P. Caraveo B. Teegarden J. Matteson S. Slassi-Sennou G. Skinner P. Connell 《Nuclear Physics B - Proceedings Supplements》1998,60(3):69-79
143.
George B. Butler David L. Skinner William C. Bond Jr. C. Lawson Rogers 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6):1437-1451
A wide variety of diunsaturated phosphonium salts have been synthesized in order to determine whether or not such structures undergo cyclopolymerization. As intermediates for these monomers, a number of previously unreported unsaturated phosphines have been prepared and characterized. Polymerization studies using a wide variety of free radical initiating conditions led to polymers in those cases which were predicted to undergo cyclopolymerization leading to five-, six-, or seven-membered rings with one exception. The properties of the polymers are consistent with the cyclopolymerization mechanism. The conversion of poly(diallyldiphenylphosphonium bromide) to polfidiallyldiphenylphosphine oxide) offers additional evidence for cyclopolymerization. Di-3-butenyldiphenylphosphonium bromide, a monomer functionally capable of forming a polymer containing an eight-membered ring, did not polymerize. Divinylphenylphosphine was found to undergo copolymerization with acrylonitrile in accordance with the cyclo-copolymerization mechanism. 相似文献
144.
A Two‐Armed Lanthanoid‐Chelating Paramagnetic NMR Probe Linked to Proteins via Thioether Linkages
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Dr. Wei‐Min Liu Dr. Simon P. Skinner Dr. Monika Timmer Anneloes Blok Dr. Mathias A. S. Hass Dr. Dmitri V. Filippov Dr. Mark Overhand Prof. Dr. Marcellus Ubbink 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(21):6256-6258
Paramagnetic NMR probes provide valuable long‐range structural information on proteins and protein complexes. A new, stable, two‐armed lanthanoid probe is reported that can be attached to a protein site‐specifically via chemically inert thioether linkages. 相似文献
145.
Dr. Franz Schilling Dr. Lisa R. Warner Dr. Naum I. Gershenzon Prof. Dr. Thomas E. Skinner Prof. Dr. Michael Sattler Prof. Dr. Steffen J. Glaser 《Angewandte Chemie (International ed. in English)》2014,53(17):4475-4479
Ultra‐high‐field NMR spectroscopy requires an increased bandwidth for heteronuclear decoupling, especially in biomolecular NMR applications. Composite pulse decoupling cannot provide sufficient bandwidth at practical power levels, and adiabatic pulse decoupling with sufficient bandwidth is compromised by sideband artifacts. A novel low‐power, broadband heteronuclear decoupling pulse is presented that generates minimal, ultra‐low sidebands. The pulse was derived using optimal control theory and represents a new generation of decoupling pulses free from the constraints of periodic and cyclic sequences. In comparison to currently available state‐of‐the‐art methods this novel pulse provides greatly improved decoupling performance that satisfies the demands of high‐field biomolecular NMR spectroscopy. 相似文献
146.
We present a two-player game with restricted information for one of the players. The game takes place on a transitive group action. The winning strategies depend on chains of structures in the group action. We also study a modification of the game with further restrictions on one of the players. 相似文献
147.
I. M. Skinner 《Optical and Quantum Electronics》1995,27(1):49-57
Use of the variational approximation to describe soliton propagation in a nonlinear optical coupler is shown formally to reduce the problem to one with the same form as CW operation of a coupler, albeit with a different form of nonlinearity. 相似文献
148.
The thermal decomposition of ethane has been reinvestigated using the single pulse, reflected shock technique. Reflected shock temperatures were corrected for boundary layer-induced nonidealities using the thermal decomposition of cyclohexene as a kinetic standard. The rate constant for the reaction was calculated from the rate of formation of methane under conditions of very low extent of reaction, over a temperature range of 1000–1241 K. Ethane compositions of 1% and 3% in argon at total reaction pressures of 3 and 9 atm were used, and a small pressure dependence of k1 was observed. An RRKM model is described which gives excellent agreement with this and other recent dissociation and recombination rate constant data in light of a recent revision to the thermochemistry of the methyl radical. In the range of 1000–1300 K an RRKM extrapolated k is given by the expression, log k = 17.2 ? 91,000/2.3RT, while at 298 K the calculation gives log k (l/mol sec) = 10.44, where k is calculated from k and the equilibrium constant. 相似文献
149.
150.
Motivated by recent work on the Ruddlesden–Popper material, which was shown to be a superior oxide-ion conductor than conventional solid-oxide fuel cell cathode perovskite materials,
we undertook A- and B-site doping studies of the Ruddlesden–Popper nickelate series in an attempt to identify other candidates
for cathode application. In this paper, we summarize our most significant results for the and systems and more recently, the higher-order Ruddlesden–Popper phases La
n+1Ni
n
O3n+1 (n=2 and 3), which show greater promise as cathode materials than the n=1 compositions. 相似文献