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361.
It has been demonstrated that the Mott-Littleton theory of dielectric constant is consistent with the recent experimental data on the pressure dependence of dielectric constant of alkali halides. On the other hand, the Clausius-Mossotti and Drude models yield large deviations from the observed data. 相似文献
362.
[formula: see text] Enzymatic resolution in combination with ruthenium-catalyzed racemization of the substrate led to dynamic kinetic resolution of alpha-hydroxy esters in good yields and excellent ee's. Studies of different parameters showed that the best results were obtained using Pseudomonas cepacia lipase, ruthenium catalyst 3, and 4-chlorophenyl acetate as acyl donor in cyclohexane. 相似文献
363.
In this paper, we study a renewal input working vacations queue with state dependent services and Bernoulli-schedule vacations. The model is analyzed with single and multiple working vacations. The server goes for exponential working vacation whenever the queue is empty and the vacation rate is state dependent. At the instant of a service completion, the vacation is interrupted and the server resumes a regular busy period with probability 1???q (if there are customers in the queue), or continues the vacation with probability q (0?≤?q?≤?1). We provide a recursive algorithm using the supplementary variable technique to numerically compute the stationary queue length distribution of the system. Finally, using some numerical results, we present the parameter effect on the various performance measures. 相似文献
364.
Chanyi Song Soo Jai Shin Hyung Jin Sung Keun-Shik Chang 《Journal of Fluids and Structures》2011,27(3):438-455
The unsteady behavior of a 2-D circular elastic capsule was investigated in three viscous shear flows. An immersed boundary method (IBM) has been used to solve the dynamic fluid-structure interaction of the capsule. Computations were carried out in finite parameter ranges where the Reynolds number is Re=1-40 and the capillary number is Ca=0.0005-0.05, which is the ratio of the external viscous shear stress to the resistant elastic tensions of the membrane. For the simple shear flow, the effect of inertia on the transient behavior of the capsule was studied. For the pulsatile shear flow, two values of the peak fluid strain, Tf=1 and 5, were considered for the quasi-steady capsule mechanics. The capsule shows a cyclic structural response that includes subharmonics as the Reynolds number is elevated to 10 and 40. The capsule dynamic response includes a phase lag, which is a function of the capillary number, the Reynolds number, and the peak fluid strain. Finally, the capsule flowing in the Couette flow shows lateral migration due to the transient lift force, which is higher for lower Ca and higher Re. When capsules with diverse elasticity are dispersed along the velocity gradient, the capsule with a hard membrane experienced greater lift than the one with a soft membrane. 相似文献
365.
Iacopi F Choi JH Terashima K Rice PM Dubois G 《Physical chemistry chemical physics : PCCP》2011,13(9):3634-3637
Plasma processing at cryogenic temperatures tremendously suppresses the depth penetration of plasma radical species within nanoporous materials. We demonstrate that this confining effect is surprisingly unrelated to changes in the phase diffusivity of radical species gas, but is determined by the increase of the sticking coefficient and the radical recombination and reaction factors, favoring an early irreversible surface adsorption of the plasma radical species. 相似文献
366.
Tumarkin E Park JI Nie Z Kumacheva E 《Chemical communications (Cambridge, England)》2011,47(47):12712-12714
This communication describes a novel strategy for the continuous microfluidic generation of highly monodispersed particle-coated microbubbles using temperature-dependent dissolution of carbon dioxide. 相似文献
367.
Lansoprazole (Prevacid) is an antiulcerative drug used for the treatment of duodenal and gastric ulcers, reflux oesophagitis, and Zollinger–Ellison syndrome. During the bulk synthesis of lansoprazole, we have observed five impurities: lansoprazole N-oxide, lansoprazole sulfone N-oxide, lansoprazole sulfide, lansoprazole sulfone and N-aralkyl lansoprazole. The present work describes the synthesis and characterization of these impurities. 相似文献
368.
Xanthan sulfuric acid (XSA) is employed as a recyclable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones. These syntheses were performed via a one-pot, three-component condensation of aldehydes, amines, and urea/thiourea under solvent-free conditions. 相似文献
369.
A. V. Belushkin A. A. Bogdzel V. V. Zhuravlev Ts. Ts. Panteleev Li Yong Jai A. N. Chernikov A. V. Churakov V. N. Shvetsov 《Technical Physics》2008,53(1):117-121
Development of new high-flux-intensity neutron sources and the need to equip them with efficient spectrometers raises the problem of designing special-purpose direct-beam monitors-detectors. These detectors feature an extremely low efficiency and a very low attenuation of the incident neutron beam. In this work, a two-coordinate position-sensitive monitor-detector is described that was developed for real-time recording of the profile of neutron beams generated by both steady and pulsed neutron sources. The basic parameters of this device are the following: a coordinate resolution of 4 × 4 mm2, a sensitive area of 100 × 100 mm2, and a recording efficiency of 10?6?10?2. Use of nitrogen as a converter makes it possible to achieve a record low efficiency and still maintain other parameters at a desired level. The device can be combined not only with high-flux-intensity neutron sources already in use worldwide but also with next-generation sources being developed in the United States (SNS) and Japan (JPARC). 相似文献
370.