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301.
Summary A new method for quantitating urinary estrogen by gasliquid chromatography is described. A minimum of 50 cm3 of urine sample is required for the preliminary enzyme hydrolysis. The hydrolysate is extracted with a mixture of ether and ethyl acetate followed by multiple washes or rotary evaporation to eliminate interfering emulsions. The estrogen fractions are silylated, concentrated and chromatographed on a 3% OV-225 column. This method combines the advantages of several procedures while eliminating many of the adverse reactions previously encountered. The method is sufficiently sensitive to quantitate estrogens in the nanogram range. 相似文献
302.
Brian Potter Rex A. Palmer Robert Withnall Michael J. Leach Babur Z. Chowdhry 《Journal of chemical crystallography》1999,29(6):701-706
The crystal and molecular structure of lamotrigine isethionate, C9H8Cl2N5
+ .HOC2H4SO3
– has been determined by direct methods. The compound crystallizes in the tetragonal space group I41/a. The isethionate moiety forms multiple hydrogen bonds to the lamotrigine nucleus, three from one isethionate, two from a symmetry related isethionate and a further two from two different symmetry related molecules. Protonation of N(2) in the triazine ring, not observed in the native lamotrigine structure is presumably associated with the interaction of the isethionate moiety. Both rings in the lamotrigine moiety are essentially planar, with a dihedral angle of 66.08(7)° compared to 80.70° in native lamotrigine. The connecting bond length C(1)—C(6) = 1.493(3) Å also correlates well with values in related compounds (1.480(3) Å) in the native structures. 相似文献
303.
Deposition of sub-monolayer silicon on SiO2/Si(1 0 0) greatly facilitates nucleation in subsequent thermal chemical vapor deposition (CVD) of silicon nanoparticles. Sub-monolayer seeding is accomplished using silicon atoms generated via disilane decomposition over a hot tungsten filament. The hot-wire process is nonselective towards deposition on silicon and SiO2, is insensitive to surface temperature below 825 K, and gives controlled coverages well below 1 ML. Thermal CVD of nanoparticles at 1×10−4 Torr disilane and temperatures ranging from 825 to 925 K was studied over SiO2/Si(1 0 0) surfaces that had been subjected to predeposition of Si or were bare. Seeding of the SiO2 surface with as little as 0.01 ML is shown to double the nanoparticle density at 825 K, and densities are increased twenty fold at 875 K after seeding the surface with 30% of a monolayer. 相似文献
304.
Finlay P Ettenauer S Ball GC Leslie JR Svensson CE Andreoiu C Austin RA Bandyopadhyay D Cross DS Demand G Djongolov M Garrett PE Green KL Grinyer GF Hackman G Leach KG Pearson CJ Phillips AA Sumithrarachchi CS Triambak S Williams SJ 《Physical review letters》2011,106(3):032501
A high-precision half-life measurement for the superallowed β+ emitter 26Al(m) was performed at the TRIUMF-ISAC radioactive ion beam facility yielding T 1/2 6346.54 ± 0.46(stat) ± 0.60 (syst) ms, consistent with, but 2.5 times more precise than, the previous world average. The 26Al(m) half-life and ft value, 3037.53(61) s, are now the most precisely determined for any superallowed β decay. Combined with recent theoretical corrections for isospin-symmetry-breaking and radiative effects, the corrected Ft value for (26)Al(m), 3073.0(12) s, sets a new benchmark for the high-precision superallowed Fermi β-decay studies used to test the conserved vector current hypothesis and determine the V(ud) element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. 相似文献
305.
C. Sophocleous P.G.L. Leach 《Journal of Computational and Applied Mathematics》2011,235(14):4158-4164
We provide the solutions for the Heston model of stochastic volatility when the parameters of the model are constant and when they are functions of time. In the former case, the solution follows immediately from the determination of the Lie point symmetries of the governing 1+1 evolution partial differential equation. This is not the situation in the latter case, but we are able to infer the essential structure of the required nonlocal symmetry from that of the autonomous problem and hence can present the solution to the nonautonomous problem. As in the case of the standard Black-Scholes problem the presence of time-dependent parameters is not a hindrance to the demonstration of a solution. 相似文献
306.
307.
W. Sinkala P. G. L. Leach J. G. O'Hara 《Mathematical Methods in the Applied Sciences》2011,34(2):152-159
The Cox–Ingersoll–Ross (CIR) model and the Vasicek model are two well‐known single factor models of the interest spot rate. In this paper, we construct a mapping by means of which the price of a zero‐coupon bond in the CIR model may be obtained from a corresponding price in the Vasicek model. We use symmetry analysis to construct this mapping and verify it by transforming three arbitrary solutions of the pricing equation in the Vasicek model into solutions of the corresponding equation in the CIR model. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
308.
Xian Zhou Sualiha Afzal Hans Wohlmuth Gerald Münch David Leach Mitchell Low Chun Guang Li 《Molecules (Basel, Switzerland)》2022,27(12)
This study aims to investigate the combined anti-inflammatory activity of ginger and turmeric extracts. By comparing the activities of individual and combined extracts in lipopolysaccharide and interferon-γ-induced murine RAW 264.7 cells, we demonstrated that ginger-turmeric combination was optimal at a specific ratio (5:2, w/w) in inhibiting nitric oxide, tumour necrosis factor and interleukin 6 with synergistic interaction (combination index < 1). The synergistic inhibitory effect on TNF was confirmed in human monocyte THP-1 cells. Ginger-turmeric combination (5:2, w/w) also upregulated nuclear factor erythroid 2–related factor 2 activity and heme oxygenase-1 protein expression. Additionally, 6-shogaol, 8-shogaol, 10-shogaol and curcumin were the leading compounds in reducing major proinflammatory mediators and cytokines, and a simplified compound combination of 6-s, 10-s and curcumin showed the greatest potency in reducing LPS-induced NO production. Our study provides scientific evidence in support of the combined use of ginger and turmeric to alleviate inflammatory processes. 相似文献