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271.
G. Brammertz A. Golubov A. Peacock P. Verhoeve D. J. Goldie R. Venn 《Physica C: Superconductivity and its Applications》2001,350(3-4):227-236
We present an application of the generalised proximity effect theory. The theory has been used to determine the energy gap (Δg) in proximised transition metal/aluminium bilayer structures such as Nb/Al, Ta/Al, V/Al and Mo/Al. These bilayers have different film thicknesses ranging from 5 to 260 nm. For the cases of Nb/Al, Ta/Al and V/Al bilayers, the interface parameters γ and γBN (here we define γ as the ratio of the products of normal state resistivity and coherence length in each film of the bilayer while γBN is the ratio of the boundary resistance between films 1 and 2 to the product of the resistivity and coherence length in the second film), which were used as input parameters to the model, were inferred experimentally from an existing bilayer of each kind and then suitably modified for different film thicknesses. This experimental assessment is therefore based on a comparison of measurements of the critical temperature and the energy gap at 300 mK with the predictions from the model for various values of γ, γBN. The energy gap of the bilayer was experimentally determined by using symmetrical superconducting tunnel junctions (STJs) of the form S–Al–AlOx–Al–S, where each electrode corresponds to a proximised bilayer. However for the case of Mo/Al bilayers the interface parameters were determined theoretically since currently no STJ data for this configuration are available. The results for the Nb/Al, Ta/Al and V/Al bilayers have also then been compared to experimentally determined energy gaps found for a series of STJs with different film thicknesses. The correspondence between experiment and theory is very good. 相似文献
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G. Bruce Guise W. David Ollis Judith A. Peacock Julia Stephanidou Stephanatou J. Fraser Stoddart 《Tetrahedron letters》1980,21(43):4203-4206
The trithiosalicylide derivatives () - () have been synthesised and shown to exist in solution as ring inverting (?*) enantiomeric helical conformations. 相似文献
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276.
Subcritical water has been recently employed as the mobile phase to eliminate the use of organic solvents in reversed-phase liquid chromatography. Although the influence of temperature on retention in subcritical water chromatography has been reported, the temperature effect on peak width and column efficiency has not yet been quantitatively studied. In this work, several polar and chlorinated compounds are separated using pure subcritical water on Zorbax RX-C8, PRP-1 (polystyrene-divinylbenzene), Hypersil ODS, and ZirChrom-polybutadiene columns. Isothermal separations are performed at temperatures ranging from 60 degrees C to 160 degrees C. The retention time and peak width of analytes are reduced with increasing temperature. However, the column efficiency is either improved or almost unchanged with the increasing temperature in the low-temperature range (lower than the 100 degrees C to 120 degrees C range), but it is decreased when temperature is further raised in the high-temperature range (higher than the 100 degrees C to 120 degrees C range). Therefore, a maximum in column efficiency is obtained at temperatures within the 100 degrees C to 120 degrees C range in most cases. 相似文献
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Karina Van Sickle Lori Marie Culberson Jeremy Levin Holzmacher Mauricio Cafiero 《International journal of quantum chemistry》2007,107(6):1523-1531
In an effort to evaluate and design fast, accurate density functional theory (DFT) methods for calculating electrostatic and dispersion interactions between proteins and ligands, we have set up a model system examining interactions between mono‐substituted benzene and indole in seven different stable conformations. We first optimized the geometries of the monomers at the B3LYP/6‐31G level, and then scanned the potential curves with MP2, HF, B3LYP, SVWN, and HCTH407 [all at the 6‐311++G(d,p) level] to find the optimum separation. We used the approximate counterpoise method to calculate the basis set superposition error‐corrected interaction energies at the optimum geometries. We then applied these methods to the interactions between aromatic active site residues of horseradish peroxidase C with indole‐3‐propionic acid at two different binding sites. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
280.
C. R. Chen Randall L. Knight Lori Pollock 《Journal of polymer science. Part A, Polymer chemistry》1987,25(1):127-136
The radicals formed in poly(methyl methacrylate) (PMMA) under vacuum by UV irradiation at room temperature were carefully examined from 77 K to 300 K by electron spin resonance (ESR). The conventional nine-line spectrum was observed with significant overall intensity changes in contrast to previous reports. The intensity decreases greatly as the temperature increases from 77 K to 100 K. The intensity of the ESR spectrum increases as the temperature increases gradually from 100 K to 260 K. The spectral changes were reversible at all temperatures. Three different models are considered to interpret the temperature dependence of the intensity of the ESR spectrum. The results indicate that the ESR spectrum depends on (1) the steady-state concentration of the propagating radical in the polymer, (2) the conformational distributions of the radicals, and (3) the environmental structures of the polymer matrix. 相似文献