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A rapid, sensitive and selective method for the determination of carbamazepine and its major metabolite in plasma has been developed. Other commonly used anticonvulsants can be determined in the same procedure without interference. After extraction with dichloromethane, the components are separated by high-pressure liquid chromatography without further clean-up or concentration on a column packed with small-particle silica gel. The mean recovery from plasma is 98.6% with a relative standard deviation of 1.6%. The detection limit for carbamazepine is approximately 2 ng/ml, requiring 1 ml of plasma. 相似文献
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Vessel diameter measurements in gadolinium contrast-enhanced three-dimensional MRA of peripheral arteries 总被引:4,自引:0,他引:4
Westenberg JJ van der Geest RJ Wasser MN van der Linden EL van Walsum T van Assen HC de Roos A Vanderschoot J Reiber JH 《Magnetic resonance imaging》2000,18(1):13-22
In this study, the possibilities for quantification of vessel diameters of peripheral arteries in gadolinium contrast-enhanced magnetic resonance angiography (Gd CE MRA) were evaluated. Absolute vessel diameter measurements were assessed objectively and semi-automatically in maximum intensity projections (MIPs) of contrast-enhanced T1-weighted 3D spoiled gradient-echo datasets, studied with digital subtraction techniques. In vivo, the complete peripheral arterial bed of six patients was studied, from the aorto-iliac bifurcation down to the distal run-off. By measuring the signal intensity (SI) over the lumen of a vessel in the MIP, an SI-plot was obtained. Next, the vessel boundaries were determined using a threshold algorithm; from these boundary points individual diameter values could be obtained along the trajectory of the vessel. In an in vitro study, an optimal threshold value of 30% of the range of SI-values between the background and the maximal SI in the vessel was obtained for accurate diameter measurement in Gd CE MRA (i.e., full-width 30%-maximum). Furthermore, the relationship between the accuracy of these measurements and the scan resolution was investigated. Accuracy was found to be acceptable (i.e., less than 10% over/underestimation) for vessel sizes covering at least 3 pixels. In six patients, diameters were measured in MIPs of the total datasets (i.e., D(T)) as well as in selective MIPs of the clipped datasets (i.e., D(S)) (n = 209). D(T) and D(S) were statistically significantly correlated (p < 0.01) with a Pearson correlation coefficient rP = 0.98. Measurements in the total MIPs yielded statistically significant (p < 0.01) smaller diameter values compared with measurements in selective MIPs, with a mean difference of 0.15 mm. Diameter values from the selective MIPs of the aorto-iliac arteries were also compared with diameter values measured at corresponding anatomic positions in X-ray angiograms of these patients (i.e., D(x)) (n = 70). D(X) and D(S) were statistically significantly correlated (p < 0.01) with a Pearson correlation coefficient rP = 0.92. Diameters measured in the selective MIPs were smaller than those measured in the X-ray angiograms (mean difference 0.49 mm) and this difference was statistically significant (p < 0.01). In conclusion, diameter values can be evaluated accurately in MIPs of vessels with at least 3 pixels in diameter, using the full-width 30%-maximum criterion. 相似文献
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Gary Pozarnsky Enrico Westenberg Odile Zarembowitch Alon McCormick 《Journal of Sol-Gel Science and Technology》1994,2(1-3):7-10
This article presents a short review of current and future trends in the synthesis of non-stoichiometric, transparent aluminosilicate gels. An overview of currently accessible compositions is also provided. 相似文献
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Werner Uhl Christian Appelt Jana Backs Hans Klöcker Andrej Vinogradov Hauke Westenberg 《无机化学与普通化学杂志》2014,640(1):106-109
The synthesis of dineopentylaluminum hydride, H‐Al(CH2CMe3)2, is known in the literature since 1988. We determined the crystal structure of this important starting material and found different ring sizes with dimeric versus trimeric formula units. The molecular shape depends on the polarity of the solvent used for recrystallization (n‐pentane or 1,2‐difluorobenzene). The synthesis of diphenylaluminum hydride, which is also long known in the literature, was optimized. It has a trimeric structure in the solid state with an Al3H3 heterocycle. 相似文献
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N. H. Furman E. R. Caley I. C. Schoonover R. A. Mc Cance H. L. Shipp G. van der Lingen G. B. van Kampen L. Westenberg W. U. Behrens E. M. Emmert E. Rupp A. Poggendorf G. F. Smith A. C. Shead H. Tollert B. Kamiénski K. Karczewski T. Gaspar 《Analytical and bioanalytical chemistry》1933,94(9-10):350-355
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Chen Dinguo Yan Yongan Westenberg Enrico Niebauer Dan Sakaitani Norikazu Chaudhuri S. Ray Sato Yoshitake Takamatsu Masahiro 《Journal of Sol-Gel Science and Technology》2000,19(1-3):77-82
Traditionally, various vacuum-based processes have been used for producing interference-type anti-reflection (AR) coatings on large area substrates for different commercial applications. In this paper, the development of sol-gel derived AR coating on large plastic substrates for display application is presented. The sol-gel dip coating process was used to deposit thin films on large size plastic panels. By developing sols with different refractive indices, multi-layer thin-film AR coating stacks were designed and fabricated. These coatings possess good uniformity and meet stringent automotive specifications. This technology has been commercialized successfully for dashboard instrument panel application in Toyota's new hybrid engine car, named Prius.In this paper, AR coatings prepared by the sol-gel process are reviewed. The basic design concept for an AR coating, the coating preparation procedure, and important parameters of the solution coating process are discussed. Optical constants of the coating materials were characterized by using spectroscopic ellipsometry. Optical, mechanical and environmental tests were performed on the sol-gel derived AR coating stack. The sol-gel derived AR coating possesses equivalent or superior properties when compared to the major commercially available AR coating products. 相似文献
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Dimeric aluminum-phosphorus compounds as masked frustrated Lewis pairs for small molecule activation
Roters S Appelt C Westenberg H Hepp A Slootweg JC Lammertsma K Uhl W 《Dalton transactions (Cambridge, England : 2003)》2012,41(30):9033-9045
Hydroalumination of aryldialkynylphosphines RP(C≡C-(t)Bu)(2) (R = Ph, Mes) with equimolar quantities of diethylaluminum hydride afforded mixed alkenyl-alkynyl cyclic dimers in which the dative aluminum-phosphorus bonds are geminal to the exocyclic alkenyl groups. Addition of triethylaluminum to isolated 1 (R = Ph) or to the in situ generated species (R = Mes) caused diethylaluminum ethynide elimination to yield the arylethylphosphorus dimers 2 and 3. These possess a chair-like Al(2)C(2)P(2) heterocycle with intermolecular Al-P interactions. The boat conformation (4) was obtained by the reaction of (t)Bu-P(C≡C-(t)Bu)(2) with di(tert-butyl)aluminum hydride. Despite being dimeric, 2 behaves as a frustrated Lewis pair and activates small molecules. The reaction with carbon dioxide gave cis/trans isomeric AlPC(2)O heterocycles that differ only by the configuration of the exocyclic alkenyl unit. Four isomers resulted from the reaction with phenyl isocyanate. This is caused by cis/trans isomerization of the initial C=O adduct and subsequent rearrangement to the AlPC(2)N heterocycle, being the C=N adduct. 相似文献
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