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31.
Stan Alama Lia Bronsard Etienne Sandier 《Transactions of the American Mathematical Society》2008,360(1):1-34
We consider the Lawrence-Doniach model for layered superconductors, in which stacks of parallel superconducting planes are coupled via the Josephson effect. To model experiments in which the superconductor is placed in an external magnetic field oriented parallel to the superconducting planes, we study the structure of isolated vortices for a doubly periodic problem. We consider a singular limit which simulates certain experimental regimes in which isolated vortices have been observed, corresponding to letting the interlayer spacing of the superconducting planes tend to zero and the Ginzburg-Landau parameter simultaneously, but at a fixed relative rate.
32.
Goff GS Brodnax LF Cisneros MR Peper SM Field SE Scott BL Runde WH 《Inorganic chemistry》2008,47(6):1984-1990
In alkaline carbonate solutions, hydrogen peroxide can selectively replace one of the carbonate ligands in UO2(CO3)3(4-) to form the ternary mixed U(VI) peroxo-carbonato species UO2(O2)(CO3)2(4-). Orange rectangular plates of K4[UO2(CO3)2(O2)].H2O were isolated and characterized by single crystal X-ray diffraction studies. Crystallographic data: monoclinic, space group P2(1)/ n, a = 6.9670(14) A, b = 9.2158(10) A, c = 18.052(4) A, Z = 4. Spectrophotometric titrations with H 2O 2 were performed in 0.5 M K 2CO 3, with UO2(O2)(CO3)2(4-) concentrations ranging from 0.1 to 0.55 mM. The molar absorptivities (M(-1) cm(-1)) for UO2(CO3)3(4-) and UO2(O2)(CO3)2(4-) were determined to be 23.3 +/- 0.3 at 448.5 nm and 1022.7 +/- 19.0 at 347.5 nm, respectively. Stoichiometric analyses coupled with spectroscopic comparisons between solution and solid state indicate that the stable solution species is UO2(O2)(CO3)2(4-), which has an apparent formation constant of log K' = 4.70 +/- 0.02 relative to the tris-carbonato complex. 相似文献
33.
Yamaguti-Sasaki E Ito LA Canteli VC Ushirobira TM Ueda-Nakamura T Dias Filho BP Nakamura CV de Mello JC 《Molecules (Basel, Switzerland)》2007,12(8):1950-1963
Chemical evaluation of the semi-purified fraction from the seeds of guaraná, Paullinia cupana H.B.K. var. sorbilis (Mart.) Ducke, yielded the following compounds: caffeine, catechin, epicatechin, ent-epicatechin, and procyanidins B1, B2, B3, B4, A2, and C1. Measurement of the antioxidant activity by reduction of the DPPH radical confirmed the anti-radical properties of the aqueous (AqE) and crude (EBPC) extracts and semi-purified (EPA and EPB) fractions. The EPA fraction showed radical-scavenging activity (RSA) and protected DPPH from discoloration at 5.23 +/- 0.08 (RSD% = 1.49) microg/mL, and for the phosphomolybdenum complex showed a higher Relative Antioxidant Capacity (RAC) at 0.75 +/- 0.01 (1.75). The EPA fraction had a total polyphenolics content of 65.80% +/- 0.62 (RSD% = 0.93). The plant drug showed 5.47% +/- 0.19 (RSD% = 3.51) and 6.19% +/- 0.08 (RSD% = 1.29) for total polyphenolics and methylxanthines, respectively. In vitro assessment of the antibacterial potential of the Paullinia cupana extracts against Streptococcus mutans showed that these could be used in the prevention of bacterial dental plaque. 相似文献
34.
Phosphor of KMgF_3:Ce~(3+)is synthesized through solvothermal method at 180℃and characterized by means of X-ray powder diffraction(XRD)and environment scanning electron microscopy(ESEM).X-ray photoelectron spectroscopy(XPS)is applied to the study of the energy band structure of KMgF_3:Ce~(3+)and confirms the oxygen content of the product is very low.The fluorescence spectra of the rare-earth ion-doped KMgF_3 is investigated by the fluorescence spectrophotometer.In the emission spectra,there is a broadban... 相似文献
35.
The effect of rare earths(Sm,Pr,Ce,Nd and La)on the hydrogenation properties of p-chloronitrobenzene(CNB)over Pt/CNTs catalyst was studied in ethanol at 303 K and normal pressure.The results exhibited that the hydrogenation of p-CNB could be carded out over PtMOx/CNTs catalysts.Both catalytic activities and yields of p-chloroaniline(CAN)were all improved.PtCeOx/ CNTs catalyst exhibited the best catalytic activity(TOF was 0.47 s~(-1))and the highest yield of p-CAN(97.5 mol%).PtCeOx/CNTs (1.0 wt%)catalyst ... 相似文献
36.
In this study,right-handed dicinnamate isosorbide was synthesized via the esterification reaction between optically active isosorbide and cinnamate.The chiral dopant was characterized by FT-IR,~1H NMR,elemental analysis,SEM,UV absorption spectrum.After dissolving in a nematic liquid crystal mixture,the chiral dopant exhibited a temperature-dependent solubility in the chiral nematic liquid crystal mixture.Meanwhile,a relatively high value of helical twisting power of the polymerizable chiral dopant was de... 相似文献
37.
Stan Alama Lia Bronsard Xavier Lamy 《Archive for Rational Mechanics and Analysis》2016,222(1):427-450
We consider energy minimizing configurations of a nematic liquid crystal around a spherical colloid particle, in the context of the Landau–de Gennes model. The nematic is assumed to occupy the exterior of a ball Br0, and satisfy homeotropic weak anchoring at the surface of the colloid and approach a uniform uniaxial state as \({|x|\to\infty}\). We study the minimizers in two different limiting regimes: for balls which are small \({r_0\ll L^{\frac12}}\) compared to the characteristic length scale \({L^{\frac 12}}\), and for large balls, \({r_0\gg L^{\frac12}}\). The relationship between the radius and the anchoring strength W is also relevant. For small balls we obtain a limiting quadrupolar configuration, with a “Saturn ring” defect for relatively strong anchoring, corresponding to an exchange of eigenvalues of the Q-tensor. In the limit of very large balls we obtain an axisymmetric minimizer of the Oseen–Frank energy, and a dipole configuration with exactly one point defect is obtained. 相似文献
38.
The integration of multiscale and multicomponent of molecules and nanoparticles into thin films for applications requires the abilities of controlled their processing and assembly,which has been an great challenge because of the difficulty in manipulating the various materials such as small molecules,complexes,polymers,and inorganic nanomaterials through synergetic combinations of chemical or physical fabrications.Eletropolymerization is of great significance to fabricate polymeric film materials straight on the conductive substrates with tunable morphologies and thicknesses.However,unlimited electrochemical reactions(polymerization)have been usually leading to disadvantageous in ill-defined structure and highly doped state.Thanks to finding of exceptional electrochemical reaction(oligomerization)of N-alkylcarbazole,electrochemical layer by layer assembly has emerged as a promising strategy for a wide library of applications.The capability of this strategy can manipulate various molecules and nanoparticles into the scale and component controllable thin films.Unlike other electropolymerizable precursors such as aniline and thiophene,the resulting di-N-alkylcarbazole is transparent in the visible light region and thus does not impair the intrinsic properties of the components in the film.This account highlights of the typical findings in investigating both single-and multi-components thin films as a forum for discussing new opportunities in exploiting novel designs and applications of optical thin films. 相似文献
39.
Functional in-chain silyl-hydride(Si-H) SBR copolymers of 4-vinyiphenyldimethylsilanol(VPDMS) and butadiene were synthesized by living anionic polymerization,in which active group Si-H was not lost and its content was controllable. Corresponding self-crosslinking elastomers were obtained by hydrosilation of Si-H group with vinyl bonds in chain.The copolymers and elastomers were characterized by ~1H NMR,size exclusion chromatography(SEC),Fourier transform infrared (FTIR) spectroscopy,differential scanning calorimetry(DSC),and thermogravimetry analysis(TGA) techniques. 相似文献
40.
Gui Rong Wang Yong Li Li Wei Dong Zhang Xian Wen Yang Wen Cong Liu Ji Ye Zhi Jun Zhu Hong Chen 《中国化学快报》2012,23(11):1251-1253
One new and 16 known compounds were isolated from Abies sibirica.Their structures were assigned mainly on the basis of NMR and MS spectroscopic data.In bioassay for anti-proliferative activity against four human tumor cells,compound 7 exhibited selective anti-proliferative activity against COLO-205 tumor cell with an IC50 value of 0.9μg/mL. 相似文献