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AA Yan LI Kai CAO ZhongHua & HU WenRui Key Laboratory of Microgravity 《中国科学:物理学 力学 天文学(英文版)》2011,(2)
The dependency of the critical Marangoni number on the geometrical aspect ratio of the floating half zone is essential to predict the onset of oscillatory thermocapillary convection.The experimental studies in the microgravity conditions on floating half zones of several centimeters in diameter have predicted that the critical Marangoni number increases with the increasing aspect ratio,and the terrestrial experimental studies have predicted the contradictory conclusion for floating half zones of several mil... 相似文献
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Non-Gravitational Effects with Density-Matching in Evaluating the Influence of Sedimentation on Colloidal Coagulation 下载免费PDF全文
The method of density matching between the solid and liquid phases is often adopted to effectively eliminate the effect of sedimentation of suspensions in studies on dynamic behaviour of a colloidal system. However, the associated changes in the solvent composition may bring side effects to the properties investigated and therefore might lead to a faulty conclusion if the relevant correction is not made. To illustrate the importance of this side effect, we present an example of the sedimentation influence on the coagulation rate of suspensions of 2μm (diameter) polystyrene. The liquid mixtures, in the proper proportions of water (H2O), deuterium oxide (D2O) and methanol (MeOH) as the liquid phase, density-matched and unmatched experiments are performed. Besides the influence of viscosity, the presence of methanol in solvent media, used to enhance the sedimentation effect, causes significant changes (reduction) in rapid coagulation rates compared to that in pure water. Without the relevant corrections for those non-gravitational factors it seems that gravitational sedimentation would retard the coagulation. The magnitude of the contribution from the non-gravitational factor is quantitatively determined, making the relevant correction possible. After necessary the influence of the sedimentation on coagulation rates at corrections for all factors, our experiments show that the initial stage of the coagulation is not observable. 相似文献
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We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented
states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among
the spinors in the coupled state. 相似文献
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V. N. Tikhonovich O. M. Zharkovskaya E. N. Naumovich I. A. Bashmakov V. V. Kharton A. A. Vecher 《Solid State Ionics》2003,160(3-4):259-270
The p(O2)–T–δ diagram of perovskite-type SrCo0.85Fe0.10Cr0.05O3−δ was determined by the coulometric titration technique in the temperature range 770–1250 K at oxygen partial pressures from 8 10−10 to 0.5 atm. Stability of the cubic perovskite phase of SrCo0.85Fe0.10Cr0.05O3−δ, existing down to the oxygen pressures of 10−3–10−5 atm, was found to be slightly higher than that of SrCo0.80Fe0.20O3−δ, probably due to stabilization of oxygen octahedra neighboring Cr4+ cations. When the oxygen nonstoichiometry of the Cr-containing perovskite decreases from 0.47 to 0.38, the partial molar enthalpy and entropy for overall oxygen incorporation reaction vary in the ranges −165 to −60 kJ mol−1 and 90 to 150 J mol−1 K−1, respectively. Within the stability limits of the single perovskite phase, the p(O2)–T–δ diagram can be adequately described by equilibrium processes of oxygen incorporation, cobalt disproportionation and interaction of cobalt and iron cations, with the thermodynamic functions independent of defect concentrations. Increasing grain size in SrCo0.85Fe0.10Cr0.05O3−δ ceramics from submicron size to 100–200 μm has no effect on the oxygen thermodynamics. The two-electrode coulometric titration technique, based on the alternate use of electrodes for oxygen pumping and e.m.f. measurements, is described and verified by studying oxygen nonstoichiometry of La0.3Sr0.7CoO3−δ and PrOx. 相似文献
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