1,452 research outputs found

    From filter to mid-range wireless power transfer system

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    In this paper, a wireless power transfer (WPT) system based on two spiral magnetic-coupled resonators is studied and realized on the printed circuit board (PCB). For the mid-range energy transfer, the microwave filter design theory can be employed to explain the basic principle of magnetic induction in WPT system. Based on the filtering transfer function, the power transfer efficiency is defined by Scattering matrix. In particular, the transfer distance between two resonators can be easily optimized according to the filtering specifications. As an example, Chebyshev function is selected to synthesize the two-pole transmission peaks, which is so-called frequency splitting in power community. Then, the transfer distances can be determined from the required external Q-factor and coupling coefficient. Finally, a PCB-based WPT system fed by two loops is designed, implemented, and verified experimentally. © 2012 IEEE.published_or_final_versio

    Main Progress of Microgravity Sciences and Space Life Sciences Research in China

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    The progress of the research activities on space material sciences, microgravity ‰uid physics and combustion, space life sciences and biotechnology research, fundamental Physics in China are brie‰y summarized in the present paper. The major space missions and experimental results obtained on board the Chinese recoverable/non-recoverable satellites and the Chinese manned spaceship named ``Shen-Zhou'' are presented summarily. The recent main activities of the ground-based studies in China are introduced in brief

    Isolation of flavonoids from mulberry (Morus alba L.) leaves with macroporous resins

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    Flavonoids are major active constituents in mulberry (Morus alba L.) leaves and possess various pharmacological activities. In the present study, the extraction technology and preparative separation oftotal flavonoids (TFs) in mulberry leaves extracts by macroporous resins were studied systematically, and the column packed with selected resin was used to perform dynamic adsorption and desorptiontests to optimize the separation process. The research results indicated that the maximal yield of TFs was achieved when mulberry leaves were extracted under the optimized conditions of a pH of 8, asolid-liquid ratio of 1:40, a temperature of 90oC and a time of 4 h. H103 resin is the most appropriate for the separation of TFs from other components in mulberry leaves extracts, which adsorption behavior canbe described with Langmuir and Freundlich isotherms and two-step adsorption kinetics model. The optimum parameters for TFs separation by H103 were achieved, after one run treatment. The recoveryand purity of TFs in the final product were 90.57 and 76.33%, respectively. In conclusion, the preparative separation of TFs in mulberry leaves can be easily and effectively done by H103 resin

    Characterization of Chlorinated Aliphatic Hydrocarbons and Environmental Variables in a Shallow Groundwater in Shanghai Using Kriging Interpolation and Multifactorial Analysis

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    CAHs, as a cleaning solvent, widely contaminated shallow groundwater with the development of manufacturing in China's Yangtze River Delta. This study focused on the distribution of CAHs, and correlations between CAHs and environmental variables in a shallow groundwater in Shanghai, using kriging interpolation and multifactorial analysis. The results showed that the overall CAHs plume area (above DIV) was approximately 9,000 m(2) and located in the 2-4 m underground, DNAPL was accumulated at an area of approximately 1,400 m(2) and located in the 6-8m sandy silt layer on the top of the muddy silty clay. Heat-map of PPC for CAHs and environmental variables showed that the correlation between 'Fe2+' and most CAHs such as '1,1,1-TCA', '1,1-DCA', '1,1-DCE' and '% TCA' were significantly positive (p<0.001), but '% CA' and/or '% VC' was not, and 'Cl-' was significantly positive correlated with '1,1-DCA' and '1,1-DCE' (p<0.001). The PCA demonstrated that the relative proportions of CAHs in groundwater were mostly controlled by the sources and the natural attenuation. In conclusion, the combination of geographical and chemometrics was helpful to establishing an aerial perspective of CAHs and identifying reasons for the accumulation of toxic dechlorination intermediates, and could become a useful tool for characterizing contaminated sites in general.published_or_final_versio

    Three-Dimensional Linear Instability Analysis of Thermocapillary Return Flow on a Porous Plane

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    A three-dimensional linear instability analysis of thermocapillary convection in a fluid-porous double layer system, imposed by a horizontal temperature gradient, is performed. The basic motion of fluid is the surface-tension-driven return flow, and the movement of fluid in the porous layer is governed by Darcy's law. The slippery effect of velocity at the fluid-porous interface has been taken into account, and the influence of this velocity slippage on the instability characteristic of the system is emphasized. The new behavior of the thermocapillary convection instability has been found and discussed through the figures of the spectrum

    Interfacial temperature discontinuities in a thin liquid layer during evaporation

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    Recent measurements of the temperature profiles across the liquid-vapor interface of a steady evaporating liquid were performed in a thin planar liquid layer subjected to externally imposed horizontal temperature differences when the interface was open to air. Temperature discontinuities have been found to exist at the interface with an growing tendency as the imposed horizontal temperature difference increasing. Under the co-influence of thermocapillary convection and evaporation effect, a thin layer of 0.5 mm thick with approximate uniform temperature was found just below the liquid-vapor interface. Repeated experiments and further comparisons of the interfacial temperature profiles for different spatial positions along the streamwise center line and varying depths of the liquid layer were also carried out. And the temperature discontinuity was found related to the temperature in liquid phase, which was strongly influenced by the coupling of thermocapillary convection and evaporation effect

    Three-Dimensional Linear Instability Analysis of Thermocapillary Return Flow on a Porous Plane

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    A three-dimensional linear instability analysis of thermocapillary convection in a fluid-porous double layer system, imposed by a horizontal temperature gradient, is performed. The basic motion of fluid is the surface-tension-driven return flow, and the movement of fluid in the porous layer is governed by Darcy's law. The slippery effect of velocity at the fluid-porous interface has been taken into account, and the influence of this velocity slippage on the instability characteristic of the system is emphasized. The new behavior of the thermocapillary convection instability has been found and discussed through the figures of the spectrum

    Studies on Anti-Hepatoma Effect of Gan-Ai-Xiao Decoction

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    Purpose: To explore the anti-hepatoma effect of Gan-Ai-Xiao Decoction (GAXD), a folk remedy.Methods: High performance liquid chromatography (HPLC) was used to identify the major chemical components of GAXD ethanol extract (EE). The cytotoxic effect of GAXD EE against HepG2 cells was measured by methyl thiazolyl tetrazolium (MTT) assay. Flow cytometry and Western blot were used to study the effect of GAXD EE on apoptosis and apoptotic proteins (Bcl-2, Bax and caspase-3) in HepG2 cells. Xenograft assay was used to evaluate the anti-hepatoma effect of GAXD EE in vivo.Results: Four components were identified in GAXD EE by HPLC. The results of MTT and flow cytometry assays indicated that GAXD EE significantly reduced HepG2 cells viability (p &lt; 0.05) and induced its apoptosis. The results of Western blot assay suggested that GAXD EE down-regulated the expression of anti-apoptotic protein (Bcl-2) and up-regulated the expression of pro-apoptotic proteins (Bax and caspase-3) in HepG2 cells. Furthermore, the results of xenograft assay showed that GAXD EE significantly inhibited the growth of HepG2 cells-induced tumor (p &lt; 0.05) without any effect on the body weight of nude mice.Conclusion: GAXD has anti-hepatoma activity, and the mechanism is associated with apoptosis.Keywords: Gan-Ai-Xiao Decoction, Anti-hepatoma, Flow Cytometry, Western Blot, Xenograft, HepG2 cells, Apoptosi

    The Convective Instabilities in a Liquid-Vapor System with a Non-equilibrium Evaporation Interface

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    Rayleigh-Marangoni-B,nard instability in a system consisting of a horizontal liquid layer and its own vapor has been investigated. The two layers are separated by a deformable evaporation interface. A linear stability analysis is carried out to study the convective instability during evaporation. In previous works, the interface is assumed to be under equilibrium state. In contrast with previous works, we give up the equilibrium assumption and use Hertz-Knudsen's relation to describe the phase change under non-equilibrium state. The influence of Marangoni effect, gravitational effect, degree of non-equilibrium and the dynamics of the vapor on the instability are discussed

    Experimental Study on the Combined Evaporation Effect and Thermocapillary Convection in a Thin Liquid Layer

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    The coupling mechanisms and flow characteristics of thermocapillary convection in a thin liquid layer with evaporating interface were studied. The planar liquid layer, with the upper surface open to air, was imposed externally horizontal temperature differences. The measured average evaporating rates and interfacial temperature profiles indicated the relative importance of evaporation effect and thermocapillary convection under different temperature gradients. A temperature jump was found at the interface, which was thought to be related to the influence of evaporation effect. All above mentioned results were repeated in a rarely evaporating liquid to compare the influence of evaporation effect
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