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191.
D Nicoll-Griffith R Zamboni J B Rasmussen D Ethier S Charleson P Tagari 《Journal of chromatography. A》1990,526(2):341-354
BIO-Fully Automated Sample Treatment (BIO-FAST) high-performance liquid chromatography (HPLC) is a sophisticated column-switching technique in which a fresh pre-column is used for each sample prior to reversed-phase HPLC. The pre-columns, Varian Advanced Automated Sample Processor (AASP) cartridges, are held and automatically advanced by the Varian AASP. A rapid and efficient extraction and separation for leukotrienes C4 and E4 from human urine has been developed using a C8 cartridge and subsequent C18 analytical HPLC column. Quantitation of leukotriene E4, accomplished by post-column radioimmunoassay, shows significantly increased leukotriene E4 concentrations in urine samples from asthmatics after antigen challenge. This further confirms an active role for leukotrienes in the pathogenesis of bronchial asthma. 相似文献
192.
Christian Lund Rasmussen Karin Hedebo Wassard Kim Dam-Johansen Peter Glarborg 《国际化学动力学杂志》2008,40(7):423-441
The oxidation of methanol in a flow reactor has been studied experimentally under diluted, fuel-lean conditions at 650–1350 K, over a wide range of O2 concentrations (1%–16%), and with and without the presence of nitric oxide. The reaction is initiated above 900 K, with the oxidation rate decreasing slightly with the increasing O2 concentration. Addition of NO results in a mutually promoted oxidation of CH3OH and NO in the 750–1100 K range. The experimental results are interpreted in terms of a revised chemical kinetic model. Owing to the high sensitivity of the mutual sensitization of CH3OH and NO oxidation to the partitioning of CH3O and CH2OH, the CH3OH + OH branching fraction could be estimated as α = 0.10 ± 0.05 at 990 K. Combined with low-temperature measurements, this value implies a branching fraction that is largely independent of temperature. It is in good agreement with recent theoretical estimates, but considerably lower than values employed in previous modeling studies. Modeling predictions with the present chemical kinetic model is in quantitative agreement with experimental results below 1100 K, but at higher temperatures and high O2 concentration the model underpredicts the oxidation rate. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 423–441, 2008 相似文献
193.
A. V. Daniel J. H. Hamilton A. V. Ramayya A. S. Fomichev Yu. Ts. Oganessian G. S. Popeko A. M. Rodin G. M. Ter-Akopian J. K. Hwang D. Fong C. Goodin K. Li J. O. Rasmussen D. Seweryniak M. Carpenter C. J. Lister Sh. Zhu R. V. F. Janssens J. Batchelder J. Kliman L. Krupa W. -C. Ma S. J. Zhu L. Chaturvedi J. D. Cole 《Physics of Atomic Nuclei》2006,69(8):1405-1408
A new experiment devoted to the fission of 252Cf is described. It continued a series of our experiments based on correlation measurements of γ rays emitted by fission fragment pairs. The measurements of γ-γ and γ-γ-γ coincidences were done at Gammasphere with closed 252Cf sources. The open source was used for the first time in the last experiment. Fission fragment detectors were arranged in
the center hole of Gammasphere. Correlations between fission fragment masses, total kinetic energy, and γ rays were observed. The first, preliminary results of data analysis are discussed.
The text was submitted by the authors in English. 相似文献
194.
Local probing of second-order susceptibilities with a near-field optical microscope is demonstrated for the first time. Using an uncoated fiber tip as a light source, near-field images of a surface of y-cut LiNbO3 crystal and of a multilayer Langmuir–Blodgett film of 2-docosylamino-5-nitropyridine are obtained at the fundamental pump and second harmonic wavelengths while simultaneously recording surface topography. It is shown that optical second-harmonic images for different polarizations of the pump light reflect the difference in magnitude of the corresponding components of the second-order susceptibility tensor. Various degrees of correlation in contrast of optical (fundamental and second harmonic) and topographical images are observed and discussed. 相似文献
195.
Zeming He Kjeld B?hm Andersen Li Keel Frederik Berg Nygaard Mohan Menon Kent Kammer Hansen 《Ionics》2009,15(4):427-431
In the present work, porous electrode materials lanthanum strontium manganate (LSM)-gadolinium-doped cerium oxide (CGO) and
electrochemical cells LSM-CGO + CGO were fabricated via the processes of slurry preparation, tape casting and lamination,
and sintering. Graphite, wheat starch, and polyamide powders were used as pore formers, respectively, in order to investigate
their effects on shrinkage, flow rate, porosity, and average pore size of the sintered samples. The observation from scanning
electronic microscope (SEM) revealed different microstructures caused by different pore formers. Porous, flat, and crack-free
electrochemical cells were successfully achieved using the present ceramic processing route. The produced cells could potentially
be used for flue gas purification. 相似文献
196.
Two-dimensional fluid simulations of interchange turbulence for geometry and parameters relevant for the scrape-off layer of magnetized plasmas are presented. The computations, which have distinct plasma production and loss regions, reveal bursty ejection of particles and heat from the bulk plasma in the form of blobs. These structures propagate far into the scrape-off layer where they are dissipated due to transport along open magnetic field lines. From single-point recordings it is shown that the blobs have asymmetric conditional wave forms and lead to positively skewed and flattened probability distribution functions. The radial propagation velocity may reach one-tenth of the sound speed. These results are in excellent agreement with recent experimental measurements. 相似文献
197.
We present experiments and theory for the "bathtub vortex," which forms when a fluid drains out of a rotating cylindrical container through a small drain hole. The fast down-flow is found to be confined to a narrow and rapidly rotating "drainpipe" from the free surface down to the drain hole. Surrounding this drainpipe is a region with slow upward flow generated by the Ekman layer at the bottom of the container. This flow structure leads us to a theoretical model similar to one obtained earlier by Lundgren [J. Fluid Mech. 155, 381 (1985)]], but here including surface tension and Ekman upwelling, comparing favorably with our measurements. At the tip of the needlelike surface depression, we observe a bubble-forming instability at high rotation rates. 相似文献
198.
199.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
200.
Carl Th. Pedersen Erik G. Frandsen Kjeld Schaumburg 《Magnetic resonance in chemistry : MRC》1977,9(9):546-552
1H and 13C n.m.r. studies of a series of twelve 1,2-dithiole-3-ylidene ketones and aldehydes have shown that the geometry of the carbon backbone is the same as found in 1,6,6aλ4-trithiapentalenes. No evidence has been found which favours a bicyclic structure for the system. A linear correlation of observed 13C chemical shifts with calculated charge densities is found to be valid. The observations are in agreement with a structure which is a hybrid between a true ketonic structure and a true mesoionic structure. By using the difference in the 13C chemical shifts of ortho and meta carbon atoms in substituent phenyl groups it is possible to qualify the degree of coplanarity of the phenyl groups with the backbone of the molecule. 相似文献