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91.
Stevie Brown Dr. Ewan Cruickshank Prof. John M. D. Storey Prof. Corrie T. Imrie Prof. Damian Pociecha Dr. Magdalena Majewska Dr. Anna Makal Prof. Ewa Gorecka 《Chemphyschem》2021,22(24):2506-2510
Liquid-crystal materials exhibiting up to three nematic phases are reported. Dielectric response measurements show that while the lower temperature nematic phase has ferroelectric order and the highest temperature nematic phase is apolar, the intermediate phase has local antiferroelectric order. The modification of the molecular structure by increasing the number of lateral fluorine substituents leads to one of the materials showing a direct isotropic-ferronematic phase transition. 相似文献
92.
Graham R. Rideal Jamie Storey Thomas R. Morris 《Particle & Particle Systems Characterization》2000,17(2):77-82
This paper describes the preparation, measurement and use of microspheres for calibrating individual test sieves. Using a 63 µm sieve as an example, 2.5 million apertures, or 80% of the surface is examined in under 2 minutes. Because of the narrowness of the size distribution, a 5% difference in percent passing only results in a mean aperture difference of 1 µm, indeed, the measurement uncertainty for all 24 tests performed was only 0.7 µm. The calibration is independent of the method of shaking and can be used for most sieves. 相似文献
93.
Maeda K Wedge CJ Storey JG Henbest KB Liddell PA Kodis G Gust D Hore PJ Timmel CR 《Chemical communications (Cambridge, England)》2011,47(23):6563-6565
We determine the spin-selective kinetics of a carotenoid-porphyrin-fullerene triad that has previously been used to establish the principle that a photochemical reaction could form the basis of the magnetic compass sensor of migratory birds and show that its magnetic sensitivity can be understood without invoking quantum Zeno effects. 相似文献
94.
In this paper, low-order Newton methods are proposed that make use of previously obtained second-derivative information by suitable preconditioning. When applied to a particular 2-dimensional Newton method (the LS method), it is shown that a member of the Broyden family of quasi-Newton methods is obtained. Algorithms based on this preconditioned LS model are tested against some variations of the BFGS method and shown to be much superior in terms of number of iterations and function evaluations, but not so effective in terms of number of gradient evaluations. 相似文献
95.
Heinrich JG Matthies Qiao Han Angela Shields Jane Wright Jessica L Moore Danny G Winder Aurelio Galli Randy D Blakely 《BMC neuroscience》2009,10(1):65-19
Background
Reuptake of synaptic norepinephrine (NE) via the antidepressant-sensitive NE transporter (NET) supports efficient noradrenergic signaling and presynaptic NE homeostasis. Limited, and somewhat contradictory, information currently describes the axonal transport and localization of NET in neurons. 相似文献96.
97.
Classical molecular dynamics modelling has been used to obtain new models of 50CaO·50P2O5 and 50MgO·50SiO2 glasses and, together with previously published models of 63CaO·37Al2O3, and 50CaO·50SiO2 glasses, these have been inspected to evaluate structural features. For the first time, models of glasses near the eutectic in three systems, aluminate, silicate, and phosphate, with the same modifier, Ca, have been compared. All have short range order which is similar to that in crystals of the same composition, 5CaO·3Al2O3, CaSiO3 and Ca(PO3)2. There is a clear trend in bonding of bridging oxygen to Ca, which is dominant in aluminate glass, common in silicate glass, and absent in phosphate glass. Preliminary results for 50MgO·50SiO2 glass show unusual behaviour because ~ 5% of oxygen is present as “non-network” oxygen, i.e. bonded only to Mg. The models show broader Qn distributions than seen in NMR experiments, and this remains an area for improvement of MD modelling of glasses. The distributions of Ca in the models have been studied using the pair distribution function TCaCa(r) which is found to be similar in the three glasses, and also similar to the previous experimental measurement for 50CaO·50SiO2 glass. The distributions of Ca are markedly different in the glasses compared to the crystals, being isotropic in the former and anisotropic in the latter, which should be a factor in glass forming ability. 相似文献
98.
We develop a simple Landau-Ginzburg-type continuum theory of solvent-free ionic liquids and use it to predict the structure of the electrical double layer. The model captures overscreening from short-range correlations, dominant at small voltages, and steric constraints of finite ion sizes, which prevail at large voltages. Increasing the voltage gradually suppresses overscreening in favor of the crowding of counterions in a condensed inner layer near the electrode. This prediction, the ion profiles, and the capacitance-voltage dependence are consistent with recent computer simulations and experiments on room-temperature ionic liquids, using a correlation length of order the ion size. 相似文献
99.
E. Butler G. B. Andresen M. D. Ashkezari M. Baquero-Ruiz W. Bertsche P. D. Bowe C. C. Bray C. L. Cesar S. Chapman M. Charlton J. Fajans T. Friesen M. C. Fujiwara D. R. Gill J. S. Hangst W. N. Hardy R. S. Hayano M. E. Hayden A. J. Humphries R. Hydomako S. Jonsell L. Kurchaninov R. Lambo N. Madsen S. Menary P. Nolan K. Olchanski A. Olin A. Povilus P. Pusa F. Robicheaux E. Sarid D. M. Silveira C. So J. W. Storey R. I. Thompson D. P. van der Werf D. Wilding J. S. Wurtele Y. Yamazaki 《Hyperfine Interactions》2011,199(1-3):39-48
Spectroscopy of antihydrogen has the potential to yield high-precision tests of the CPT theorem and shed light on the matter-antimatter imbalance in the Universe. The ALPHA antihydrogen trap at CERN??s Antiproton Decelerator aims to prepare a sample of antihydrogen atoms confined in an octupole-based Ioffe trap and to measure the frequency of several atomic transitions. We describe our techniques to directly measure the antiproton temperature and a new technique to cool them to below 10 K. We also show how our unique position-sensitive annihilation detector provides us with a highly sensitive method of identifying antiproton annihilations and effectively rejecting the cosmic-ray background. 相似文献
100.
Abstract Living polymerization of isobutylene was achieved using an initiation system based on either 1,3-di(1-chloro-l-methylethyl)-5-tert-butylbenzene (tert-butyl-dicumyl chloride) or 1,3,5-tris(l-chloro-l-methylethyl)benzene (tricumyl chloride) in conjunction with TiCl4, and pyridine in hexanes/methyl chloride (60/40, v/v) cosolvents. TiCl4/pyridine was found to yield narrow molecular weight distribution (MWD ≈ 1.1) and quantitative initiation efficiency (Ieff < 90%). The living nature of the polymerization system was demonstrated by the linearity of molecular weight vs conversion plots and first-order kinetic plots up to about 90% monomer conversion. If polymerization was allowed to proceed further, a departure from first-order kinetics and a broadening of the molecular weight distribution was observed to occur. The living polymerization was investigated as a function of temperature, reaction time, and the concentration of TiCl4/pyridine. Polymerization rates were observed to increase with decreasing temperature and/or increasing concentration of TiCl4/pyridine. Number-average molecular weights of the polyisobutylenes ranged from 5,000 to 100,000 under the conditions employed. 相似文献