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31.
Alexopoulos T Allen C Anderson EW Balamurali V Banerjee S Beery PD Bhat P Bishop JM Biswas NN Bujak A Carmony DD Carter T Choi Y Cole P DeBonte R DeCarlo V Erwin AR Findeisen C Goshaw AT Gutay LJ Hirsch AS Hojvat C Jennings JR Kenney VP Lindsey CS Loomis C LoSecco JM McMahon T McManus AP Morgan N Nelson K Oh SH Porile NT Reeves D Rimai A Robertson WJ Scharenberg RP Stampke SR Stringfellow BC Thompson M Turkot F Walker WD Wang CH Warchol J Wesson DK Zhan Y 《Physical review D: Particles and fields》1993,48(3):984-997
32.
D. W. Schwendeman M. C. A. Kropinski J. D. Cole 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1993,44(3):556-571
Numerical calculations are carried out in the hodograph plane to construct optimal critical airfoil shapes and the flow about them. These optimal airfoil shapes give the highest free-stream Mach numberM
for a given thickness ratio and tail angle
t
(nonlifting) for which the flow is nowhere supersonic. A relationship betweenM
and for various
t
is given. Analytical and numerical solutions to the same problem are found on the basis of transonic small-disturbance theory. These results provide a limiting case asM
1, 0 and agree well with the calculations of the full problem. Using a numerical method to calculate the flow about general (subsonic) airfoils, a comparison is made between the critical free-stream Mach numbers for some standard airfoil shapes and the optimal free stream Mach number of the corresponding and
t
. A significant increase in the critical free-stream Mach number is found for the optimal airfoils. 相似文献
33.
34.
Electrospray ionization (ESI) combined with tandem mass spectrometry (MS/MS) was utilized for the structural confirmation of lipid A derived from Enterobacter agglomerans, a Gram-negative bacterium commonly found in field cotton. Previous ESI-MS studies conducted in our laboratory found that similarities exist between the fatty acid side-chains in the lipid A of E. agglomerans and that of Salmonella minnesota. It was noted that heterogeneity at the fatty acyl chain at position 3' of the diglucosamine backbone of E. agglomerans can take the form of either a myristyloxymyristyl group or, less commonly, a hydroxymyristyloxymyristyl moiety. In this work, tandem mass spectra obtained from heptaacyl and hexaacyl lipid A precursors derived from E. agglomerans and a known standard S. minnesota were compared to assist in structural elucidation. These ESI-MS/MS experiments confirmed the previously reported structure for lipid A derived from E. agglomerans. Moreover, MS/MS data indicated that the additional hydroxyl group of the 3'-position hydroxymyristyloxymyristyl moiety is present as the alpha-isomer. 相似文献
35.
36.
37.
The reaction between Cr(CO)5[C6H6] and ethyl diazoacetate (EDA) has been studied using the technique of laser flash photolysis. Results indicate that the Cr(CO)5 fragment reacts very rapidly with the EDA ligand. Low temperature spectroscopic studies suggest that in the case of W(CO)5, and by analogy also in the case of Cr(CO)5, the initial adduct between the pentacarbonyl fragment and EDA is one where the oxygen atom of the diazocarbonyl ligand is bound to the metal center. This kinetic product is then converted to a thermodynamically favored complex which is tentatively assigned as the nitrogen bound W(CO)5-EDA complex that appears to be stable at r.t. 相似文献
38.
Semimicro titrimetric procedures and micro high-performance liquid chromatographic procedures are described for the determination of aliphatic and aromatic thiols, based on the highly selective reaction with aromatic thiosulfonates. The reaction products, a sulfinic acid and a mixed disulfide, contain an aromatic moiety, permitting the use of an u.v. detector. The chromatographic procedure offers the advantages of application to mixtures, coupled with cross-checking of the determination by material balance from simultaneous measurement of the two reaction products. 相似文献
39.
The effect of adding linear polymers to a novel reversible electrophoretic was measured. Reversible gels are formed using the polyanionic carbohydrate polymer, gellan gum. Gellan gum forms strong stable gels in the presence of divalent cations or diamines. The gels are reversible (return to solution) by changing the ionic environment or pH. Gellan gum is an anionic polymer, and the electrophoresis gels have considerable electroosmotic flow (EOF) toward the negative electrode. We measured the EOF in gellan gum electrophoresis gels as a function of gel concentration, buffer composition, and linear polymer additive. The linear polymers used in this study were polyethylene oxide and hydroxyethyl cellulose. Both polymers reduced EOF in the gels, in a manner dependent on molecular weight. Polymers with high molecular weight were more effective at reducing EOF. The addition of polymers increased the resolution of low molecular weight DNA. Native gellan gum resolved DNA from approx 50,000 to 1000 bp. Addition of the polymers resolved DNA down to approx 50 bp, in some instances. The influence of the polymers on circular plasmid DNA was also investigated. Addition of high molecular weight polyethylene oxide reduced the electrophoretic mobility of the nicked circular form compared to the supercoiled form. 相似文献
40.
Weawkamol Leelapornpisit Minh‐Tan Ton‐That Florence Perrin‐Sarazin Kenneth C. Cole Johanne Denault Benoit Simard 《Journal of Polymer Science.Polymer Physics》2005,43(18):2445-2453
The effect of different concentrations of single‐walled carbon nanotubes (SWNTs) on the nonisothermal crystallization kinetics, morphology, and mechanical properties of polypropylene (PP) matrix composites obtained by melt compounding was investigated by means of X‐ray diffraction, differential scanning calorimetry, optical and scanning electron microscopy, and dynamic mechanical thermal analysis. Microscopy showed well‐dispersed nanotube ropes together with small and large aggregates. The modulus was found to increase by about 75% at a level of 0.5 wt % nanotubes. The SWNTs displayed a clear nucleating effect on the PP crystallization, favoring the α crystalline form rather than the β form. The crystallization kinetics analysis showed a significant increase in activation energy on incorporating nanotubes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2445–2453, 2005 相似文献