We study minimizers of the Lawrence–Doniach energy, which describes equilibrium states of superconductors with layered structure, assuming Floquet-periodic boundary conditions. Specifically, we consider the effect of a constant magnetic field applied obliquely to the superconducting planes in the limit as both the layer spacing s → 0 and the Ginzburg–Landau parameter \({\kappa = \epsilon^{-1} \to \infty}\), under the hypotheses that \({s=\epsilon^\alpha}\) with 0 < α < 1. By deriving sharp matching upper and lower bounds on the energy of minimizers, we determine the lower critical field and the orientation of the flux lattice, to leading order in the parameter \({\epsilon}\). To leading order, the induced field is characterized by a convex minimization problem in \({\mathbb {R}^3}\). We observe a “flux lock-in transition”, in which flux lines are pinned to the horizontal direction for applied fields of small inclination, and which is not present in minimizers of the anisotropic Ginzburg–Landau model. The energy profile we obtain suggests the presence of “staircase vortices”, which have been described qualitatively in the physics literature. 相似文献
Plant cystoliths are mineralized objects that are formed by specialized cells in the leaves of certain plants. The main mineral component of cystoliths by volume is amorphous calcium carbonate (ACC) and the minor component is silica. We show that the silica stalk is formed first and is essential for ACC formation. Furthermore, the cystolith is shown to be composed of four distinct mineral phases with different chemical properties: an almost pure silica phase grades into a Mg-rich silica phase. This Mg-rich silica is overlaid by a relatively stable ACC phase. A bulky and less stable ACC phase encapsulates the first ACC phase. This architecture poses interesting questions about the role of Mg in the silica phase and suggests a strategy for ACC stabilization that takes advantage of a precise regulation of the mineral-growth microenvironment. 相似文献
A Keggin-type tungstosilicate compound [Co^Ⅱ(2,2′-bipy)2(H2O)]2[SiW^Ⅵ12O40]·2H2O 1 (bipy = bipyridine) was prepared by a hydrothermal method for the first time. Single-crystal X-ray diffraction revealed that 1 (C40H40Co2N8O44SiW12) crystallizes in the triclinic system, space group P1 with a = 10.4979(6), b = 13.3946(7), c = 13.5756(8)A, α= 70.0769(18), β = 68.910(3), γ = 74.186(4)°, V = 1649.84(16)A^3, Mr = 3688.95, Z = 1, Dc = 3.713 mg·m^-3, μ = 21.432 mm^-1, F(000) = 1644, S = 1.058, the final R = 0.0511 and wR =0.1023 for 6523 observed reflections (I 〉 2σ(I)). Compound 1 consists of two coordinated cation fragments [Co^Ⅱ(2,2′-bipy)2(H2O)]^2+, one normal Keggin polyanion unit [SiW^Ⅵ12O40]^4- and two lattice water molecules. To be noted, each polyanion unit is linked to two cation fragments by its two surface terminal oxygen atoms and two cobalt atoms of two cation fragments forming an organic-inorganic hybrid unit in 1. Furthermore, the compound shows strong photoluminescence property in the solid state at room temperature. 相似文献
6-(2-Hydroxy-5-acetylphenyl)-apigenin (1),a new flavonoid with a phenyl substituent,was first isolated from Selaginella tamariscina.Its structure was elucidated on the basis of 1D and 2D NMR as well as ESI-HR-MS spectroscopic analysis. 相似文献
In an attempt to search for more potent positive inotropic agents,a series of 1-(benzylamino)-3-(4,5-dihydro[1,2,4]trizaolo[4,3- a]quinolin-7-yloxy)propan-2-ol derivatives was synthesized in four steps using 6-hydroxy-3,4-dihydro-2(1H)-quinolinone as a starting material,and their positive inotropic activities were evaluated by measuring the coronary blood flow(CBF)and the left ventricular pressure(LVP)followed by calculating the rate of pressure development(dp/dt_(max)values)in the preparation of rat Lan... 相似文献
A hydrophobic hypercrosslinked polymeric resin LC-1 was prepared and characterized.The properties of LC-1 resin were compared with those of a commercial hypercrosslinked polymer NDA-201 resin.In addition,the dynamic adsorption of trichloroethylene(TCE)onto LC.1 under dry and humid conditions at 303 K was investigated,the result shows that LC-1possesses high hydrophobic property and can remove TCE from gas stream without effect of high humidity efficiently. 相似文献
Vinasse, from sugar and ethanol production, stands out as one of the most problematic agroindustry wastes due to its high chemical oxygen demand, large production volume, and recalcitrant compounds. Therefore, the viability of using glycerin as a co-substrate in vinasse anaerobic digestion was tested, to increase process efficiency and biogas productivity. The effect of feeding strategy, influent concentration, cycle length, and temperature were assessed to optimize methane production. Glycerin (1.53% v/v) proved to be a good co-substrate since it increased the overall methane production in co-digestion assays. CH4 productivity enhanced exponentially as influent concentration increased, but when temperature was increased to 35 °C, biogas production was impaired. The highest methane productivity and yield were achieved using fed-batch mode, at 30 °C and at an organic loading rate of 10.1 kg COD m−3 day−1: 139.32 mol CH4 m−3 day−1, 13.86 mol CH4 kg CODapplied, and 15.30 mol CH4 kg CODremoved. Methane was predominantly produced through the hydrogenotrophic route. In order to treat all the vinasse produced by a mid-size sugar and ethanol plant, nine reactors with 7263.4 m3 each would be needed. The energy generated by burning the biogas in boilers would reach approximately 92,000 MW h per season and could save up to US$ 240,000.00 per month in diesel oil demand.