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Norfloxacin, a nalidixic acid analog with antimicrobial properties, exists in different hydrated forms. Three of these crystal forms were reproducibly prepared and characterized by analytical techniques that included infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, solution microcalorimetry and pulsed nuclear-magnetic resonance spectroscopy.These studies showed that the dihydrate is the thermodynamically stable entity at ambient temperatures and humidities. 相似文献
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Self-injection length in La0.7Ca0.3MnO3-YBa2Cu3O7-δ ferromagnet-superconductor multilayer thin films
We have carried out extensive studies on the self-injection problem in barrierless heterojunctions between La0.7Ca0.3MnO3 (LCMO) and YBa2Cu3O7-δ (YBCO) thin films. The heterojunctions were formed in situ by sequentially growing LCMO and YBCO films on 〈100〉 LaAlO3 (LAO) substrate using a pulsed laser deposition (PLD) system. YBCO micro-bridges with 64 μm width were patterned both on
the LAO (control) and LCMO side of the substrate. Critical current, I
c, was measured at 77 K on both the control side as well as the LCMO side for different YBCO film thickness. It was observed
that while the control side showed a J
c of ∼ 2 × 106 A/cm2, the LCMO side showed about half the value for the same thickness (1800 ?). The difference in J
c indicates that a certain thickness of YBCO has become ‘effectively’ normal due to self-injection. From the measurement of
J
c at two different thicknesses (1800 ? and 1500 ?) of YBCO films both on the LAO as well as the LCMO side, the value of self-injection
length (at 77 K) was estimated to be ∼ 900 ?. To the authors’ best knowledge, this is the first time that self-injection length
has been quantified. A control experiment carried out with LaNiO3 deposited by PLD on YBCO did not show any evidence of self-injection. 相似文献
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Study of magnetoresistance and conductance of bicrystal grain boundary in La0.67Ba0.33MnO3 thin film
La0.67Ba0.33MnO3 (LBMO) thin film is deposited on a 36.7°C SrTiO3 bicrystal substrate using laser ablation technique. A microbridge is created across bicrystal grain boundary and its characteristics
are compared with a microbridge on the LBMO film having no grain boundary. Presence of grain boundary exhibits substantial
magnetoresistance ratio (MRR) in the low field and low temperature region. Bicrystal grain boundary contribution in MRR disappears
at temperature T>175 K. At low temperature, I-V characteristic of the microbridge across bicrystal grain boundary is nonlinear. Analysis of temperature dependence of dynamic
conductance-voltage characteristics of the bicrystal grain boundary indicates that at low temperatures (T<175 K) carrier transport across the grain boundary in LBMO film is dominated by inelastic tunneling via pairs of manganese
atoms and tunneling through disordered oxides. At higher temperatures (T>175 K), magnetic scattering process is dominating. Decrease of bicrystal grain boundary contribution in magnetoresistance
with the increase in temperature is due to enhanced spin-flip scattering process. 相似文献
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Molar extinction coefficients of some carbohydrates viz. l-arabinose (C5H10O5), d-glucose (C6H12O6), d-mannose (C6H12O6), d-galactose (C6H12O6), d(-) fructose (C6H12O6) and maltose (C12H24O12) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a
narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter
polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying
within experimental uncertainty. Within concentration ranges studied, Beer-Lambert law is obeyed very well. 相似文献
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de Alwis SP 《Physical review D: Particles and fields》1992,46(12):5429-5438
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Paradigm confirmed: the first use of ionic liquids to dramatically influence the outcome of chemical reactions 总被引:3,自引:0,他引:3
It has been an unproven paradigm that the choice of which ionic liquid to use in a chemical reaction can have a dramatic effect on the outcome of that chemical reaction. We demonstrate, for the first time, that the reaction of toluene and nitric acid in three different ionic liquids gives rise to three completely different products in high yield. Furthermore, ionic liquids can catalyze these reactions with the only byproduct being water. [reaction: see text] 相似文献
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Arce A Earle MJ Katdare SP Rodríguez H Seddon KR 《Physical chemistry chemical physics : PCCP》2008,10(18):2538-2542
The recently discovered class of ionic liquids--mutually immiscible ionic liquids--are explored in this work for their first practical application: the separation of aromatic and aliphatic hydrocarbons by solvent extraction. For this preliminary approach, benzene and hexane were chosen as representatives of each group of hydrocarbons; the ionic liquids 1-ethyl-3-methylimidazolium bis( (trifluoromethyl)sulfonyl)amide and trihexyl(tetradecyl)phosphonium bis( (trifluoromethyl)sulfonyl)amide, which are both liquid at room temperature and hydrophobic, were selected as potential solvents. Liquid-liquid equilibrium experiments were carried out at 25 degrees C for the quaternary system formed by the two hydrocarbons and the two ionic liquids. Typical extraction parameters were calculated and analysed in order to evaluate the possibilities of the mutual immiscible ionic liquids in accomplishing the separation target. A comparison with the case of using just one of the ionic liquids was made. 相似文献