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排序方式: 共有375条查询结果,搜索用时 218 毫秒
21.
Annia H. Kycia Kallum Koczkur J. Jay Leitch Jacek Lipkowski Vlad Zamlynny Michael W. P. Petryk 《Analytical and bioanalytical chemistry》2013,405(5):1537-1546
Polarization modulation–infrared reflection absorption spectroscopy (PM-IRRAS) was employed to analyze two unique samples: (1) an industrially prepared alkoxysilane-pretreated aluminum alloy (AA6111) in the absence and presence of a ~600-nm-thick lubricant coating and (2) a chemical warfare agent simulant, triethyl phosphate (TEP), on glass. For the pretreated aluminum samples, PM-IRRAS spectra were analyzed for three distinct regions; the SiO stretching vibration around 1120 cm?1, the NH2 bending mode at ~1600 cm?1 and the CH stretching region around 2900 cm?1. Our results showed that increasing the curing temperature (from 55 to 100 °C) improved the overall extent of cross-linking within the siloxane network. In addition, the spectra of lubricant (top coating) and the underlying siloxane layer for the aluminum samples with lubricant were collected for the same sample. Our results show that the nature of the siloxane film remains intact and unaltered after deposition of the lubricant top-coat. For detection of TEP on glass, the band at 1268 cm?1, corresponding to the P═O vibration, was monitored. A droplet of TEP solution in dichloromethane was deposited on glass. After solvent evaporation had occurred, the intensity of the P═O vibration band was used to construct calibration curves to determine the experimental limit of detection, which was found to be ~200 μg for TEP on glass. Figure
Schematic of a akoxysilane network and PM-IRRAS spectrum of the alkoxysilane film at aluminum surface 相似文献
22.
Pavel F. Vlad Alexandru G. Ciocarlan Mihai N. Coltsa Alexandr V. Baranovsky Natalya B. Khripach 《合成通讯》2013,43(22):3960-3972
This article describes a new efficient synthesis of drim-7,9(11)-diene and its hydroxylated derivates from drim-8-en-7-one. Reduction of this ketone with NaBO4 in the presence of CeCl3 · 7H2O afforded regio- and stereoselectively drim-8-en-7β-ol in a high yield. Its dehydration with H2SO4 under mild conditions led to drim-7,9(11)-diene. Noncatalytic oxidation of drim-7,9(11)-diene with OsO4 and the catalytic oxidation with the pair OsO4–NMO gave, in a high yield, depending on conditions, driman-7β,8β,9α,11-tetraol or its mixture with drim-7-en-9α,11-diol and drim-9(11)-en-7α,8α-diol. Under optimal conditions the total yield of these diols reached 89%. The separate, noncatalytic oxidation of drim-7-en-9α,11-diol and of drim-9(11)-en-7α,8α-diol with OsO4 afforded driman-7α,8α,9α,11-tetraol. 相似文献
23.
Vlad Ionescu 《Integral Equations and Operator Theory》1999,34(1):45-55
Based on the Ben Artzi-Gohberg result concerning the equivalence between the invertibility of theL
2-operator
and the exponential dichotomic evolution defined byA(t), the time-varying counterpart of the Redheffer theorem is considered under relaxed conditions. 相似文献
24.
Using the method of positions of the complex singularities, we identify a class of new, exact solutions of the Flierl-Petviashvili equation. The solutions are periodic and have the geometry of the zonal flow. We examine the physical properties and find that the solution can reproduce data from experimental observations and numerical simulations. 相似文献
25.
Mitlin V 《Journal of colloid and interface science》2004,278(1):173-183
We consider a general form of the local gradient theory for structural forces in thin fluid films near the critical point. A complete analytical solution of this problem at separation distances substantially larger than the molecular size is presented. That is, pi= -[330Psi(-4)H(8.8923-Psi) + 384exp(-Psi)H(Psi-8.8923)]H(-Gamma)+[1134.36Psi(-4)H(8.8923-Psi + 192exp(-Psi)H(Psi-8.8923)]H(Gamma) where Gamma <0 for similar (both attractive or both repulsive) and Gamma >0 for dissimilar (one attractive, another repulsive) bounding surfaces. Here pi and Psi are the structural force and the separation distance scaled in a certain way, and H(.) is a unit step function. For binary polymer films, the results are further elaborated to include a scaling dependence of the structural force on polymerization degrees of components. 相似文献
26.
The statistical properties of the turbulent field consisting of drift waves randomly interacting with a coherent structure are investigated. By using a nonperturbative method (analogous to the "semiclassical" approach in quantum mechanics), we calculate explicitly the generating functional of the correlations. 相似文献
27.
20-Deoxoluteone has been synthesized from sclareol. Sclareol was brominated with phosphorus tribromide to form a mixture of
primary allyl bromides, from which, by the malonic synthesis, a mixture of bicyclogeranylgeranylacetic acids was obtained
which was cyclized with fluorosulfonic acid to form a mixture of two diastereomeric δ-lactones. The predominating lactone
was converted by successive reduction with lithium tetrahydroaluminate, oxidation with oxalyl chloride in dimethyl sulfoxide,
reaction with methylmagnesium iodide, and oxidation by the chromium trioxide/pyridine complex into 20-deoxyluteone.
Institute of Chemistry, Moldavian SSR Academy of Science, Kishinev. Translated from Khimiya Prirodnykh Soedinenii, No. 3,
pp. 346–353, May–June, 1990. 相似文献
28.
It has been shown that the opening of the cyclopropane ring in (1R, 2S, 7S, 10S, 11R, 12S, 13S)-2,6,6,10,12-pentamethylpentacyclo[10.2.1.01,10.02,7.011,13]pentadecane takes place under the action of fluorosulfonic acid at all three carbon-carbon bonds, but at low temperatures the main isomerization product is (1R, 2S, 7S, 10S, 12S, 13S)-2,6,6,10,12-pentamethyltetracyclo[10.2.1.01,10.02,7]pentadecan-13-ol, and at the ordinary temperature the main products are (1R, 2S, 7S, 11S, 12R, 13R)-2,6,6,11,13-pentamethyltetracyclo[10.2.1.01,10.02,7]pentadeca-9-ene and (1S, 2R, 11S, 12R, 15R)-2,7,7,11,15-pentamethyltetracyclo[10.2.1.02,11.03,8]pentadeca-3(8)-ene. 相似文献
29.
30.
This paper describes a coupling framework for parallel execution of different solvers for multi-physics and multi-domain simulations with an arbitrary number of adjacent zones connected by different physical or overlapping interfaces. The coupling architecture is based on the execution of several instances of the same coupling code and relies on the use of smart edges (i.e., separate processes) dedicated to managing the exchange of information between two adjacent regions. The collection of solvers and coupling sessions forms a flexible and modular system, where the data exchange is handled by independent servers that are dedicated to a single interface connecting two solvers’ sessions. Accuracy and performance of the strategy is considered for turbomachinery applications involving Conjugate Heat Transfer (CHT) analysis and Sliding Plane (SP) interfaces. 相似文献