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971.
Tokuda H Tsuzuki S Susan MA Hayamizu K Watanabe M 《The journal of physical chemistry. B》2006,110(39):19593-19600
Room-temperature ionic liquids (RTILs) are liquids consisting entirely of ions, and their important properties, e.g., negligible vapor pressure, are considered to result from the ionic nature. However, we do not know how ionic the RTILs are. The ionic nature of the RTILs is defined in this study as the molar conductivity ratio (Lambda(imp)/Lambda(NMR)), calculated from the molar conductivity measured by the electrochemical impedance method (Lambda(imp)) and that estimated by use of pulse-field-gradient spin-echo NMR ionic self-diffusion coefficients and the Nernst-Einstein relation (Lambda(NMR)). This ratio is compared with solvatochromic polarity scales: anionic donor ability (Lewis basicity), E(T)(30), hydrogen bond donor acidity (alpha), and dipolarity/polarizability (pi), as well as NMR chemical shifts. The Lambda(imp)/Lambda(NMR) well illustrates the degree of cation-anion aggregation in the RTILs at equilibrium, which can be explained by the effects of anionic donor and cationic acceptor abilities for the RTILs having different anionic and cationic backbone structures with fixed counterparts, and by the inductive and dispersive forces for the various alkyl chain lengths in the cations. As a measure of the electrostatic interaction of the RTILs, the effective ionic concentration (C(eff)), which is a dominant parameter for the electrostatic forces of the RTILs, was introduced as the product of Lambda(imp)/Lambda(NMR) and the molar concentration and was compared with some physical properties, such as reported normal boiling points and distillation rates, glass transition temperature, and viscosity. A decrease in C(eff) of the RTILs is well correlated with the normal boiling point and distillation rate, whereas the liquid-state dynamics is controlled by a subtle balance between the electrostatic and other intermolecular forces. 相似文献
972.
W. Scandale A. Vomiero E. Bagli S. Baricordi P. Dalpiaz M. Fiorini V. Guidi A. Mazzolari D. Vincenzi R. Milan Gianantonio Della Mea E. Vallazza A.G. Afonin Yu.A. Chesnokov V.A. Maisheev I.A. Yazynin V.M. Golovatyuk A.D. Kovalenko A.M. Taratin A.S. Denisov Yu.A. Gavrikov Yu.M. Ivanov L.P. Lapina L.G. Malyarenko V.V. Skorobogatov V.M. Suvorov S.A. Vavilov D. Bolognini S. Hasan M. Prest 《Physics letters. [Part B]》2010
Different kinds of deflection in a silicon crystal bent along the 〈111〉 axis was observed for 150 GeV/c negative particles, mainly π− mesons, at one of the secondary beams of the CERN SPS. The whole beam was deflected to one side in quasi-bound states of doughnut scattering (DSB) by atomic strings with the efficiency (95.4 ± 0.2)% and with the peak position close to the bend crystal angle, α=185 μrad. It was observed volume capture of π− mesons into the DSB states with a probability higher than 7%. A beam deflection opposite to the crystal bend was observed for some orientations of the crystal axis due to doughnut scattering and subsequent multiple volume reflections of π− mesons by different bent planes crossing the axis. 相似文献
973.
Resistance memory devices based on a Cu/Mg‐doped ZnO/indium‐tin‐oxide structure on a PET (polyethylene terephthalate) flexible substrate were fabricated. The devices showed stable bipolar resistance switching property and good flexibility. The high to low resistance ratio was larger than 30 times, the endurance was more than 102 cycles, and the resistance retention was longer than 104 s. The resistance values of both high and low resistance states were not significantly changed by bending in a radius (≥20 mm) for more than 103 times. This resistance switching phenomenon of our devices can be explained by creation/rupture of metal conductive channels induced by electrochemical migration of Cu ions. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
974.
A. A. Usmani Z. Hasan F. Rahaman Sk. A. Rakib Saibal Ray Peter K. F. Kuhfittig 《General Relativity and Gravitation》2010,42(12):2901-2912
This paper discusses a new type of thin-shell wormhole constructed by applying the cut-and-paste technique to two copies of
a charged black hole in generalized dilaton-axion gravity, which was inspired by low-energy string theory. After analyzing
various aspects of this thin-shell wormhole, we discuss its stability to linearized spherically symmetric perturbations. 相似文献
975.
Hasan Efeog
lu Tevhit Karacali Kadem Meral brahim Y. Erdog
an Yavuz Onganer 《Journal of luminescence》2010,130(1):157-162
Photoluminescence (PL) of Al2O3 films obtained by anodization of thermally evaporated and annealed thin Al films on p++Si in 0.3 M oxalic acid has been investigated. Thermal annealing at 200–950 °C under the dry nitrogen atmosphere was used for deactivation of luminescence centres. Luminescence from as grown films was broad and located at 425 nm. This luminescence reached to highest level after annealing at 600 °C. Maximum 10 min was required for full optical activation and prolonged annealing up to 4 h did not change the luminescence intensity. Because of deep levels, absorption band edge of as grown films was shifted to the lower energy which is 3.25 eV. Annealing above 800 °C reduced the PL intensity and this observation was correlated with the blue shift of band edge as the defects annealed out. Disappearing PL intensity and blue shift of band edge absorption after annealing at 950 °C was mainly attributed to the oxygen-related defects and partly to impurities that may be originated from oxalic acid. AFM results did not show any hexagonally ordered holes but uniformly distributed nanosized Al2O3 clusters that were clearly seen. XRD measurements on as grown Al2O3 showed only [1 1 0] direction of α phase. Debye–Scherer calculation for this line indicates that cluster size is 35.7 nm. XRD and AFM pictures suggest that nanocrystalline Al2O3 are embedded in amorphous Al2O3. 相似文献
976.
977.
978.
Li Qiu MAO Tong Lai ZHANG Chang Gen FENG Qing Ze JIAO Da Zhen JIANG Department of mechano-electronic Engineering Beijing Institute of Technology Beijing Department of Chemistry Jilin University Changchun 《中国化学快报》2001,(6)
Silicon-magnesium catalyst, aluminum phosphate, ZSM, synthetical mordenite exchanged with alkaline-earth metals ion and acidic oxide, their catalytic properties in the ammoniation of methanol have been reported1~5. However, so far the ammoniation of methanol catalyzed by natural mordenite has not been reported. In the present work, we report the characterization and catalytic properties of natural mordenite catalysts.NH3-TPD was used to measure the acidic properties of these zeolites. The a… 相似文献
979.
980.