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1.
V. Degiorgio M. Corti R. Piazza L. Cantú A. R. Rennie 《Colloid and polymer science》1991,269(5):501-505
The structure of aqueous solutions of two polyoxyethylene non-ionic amphiphiles, C10E5 and C8E4, is studied by small-angle neutron-scattering along isothermal paths crossing the isotropic single-phase region from 0% to 100% amphiphile volume fractions. The scattered intensityI(k) shows a peak at a valuek
m
, which grows monotonically as the amphiphile volume fraction increases. The interpretation of the scattering data lead to the following conclusion: as increases the micellar structure becomes less and less sharp, but some orientational correlations between neighboring amphiphile molecules are preserved even in the pure amphiphile phase. 相似文献
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Cyclodehydration of achiral or racemic aryl-delta-oxoacids with (R)-phenylglycinol stereoselectively affords chiral non-racemic bicyclic lactams, from which the enantiodivergent synthesis of (R)- and (S)-2-phenylpiperidine, the diastereodivergent synthesis of cis- and trans-3-ethyl-2-phenylpiperidine, and the enantioselective synthesis of the piperidine alkaloid (-)-anabasine is reported. 相似文献
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B. Cantó C. Coll E. Sánchez S. C. Cardona J. Navarro-Laboulais 《Journal of mathematical chemistry》2014,52(4):1023-1035
The dynamics of the composition of chemical species in reacting systems can be characterized by a set of autonomous differential equations derived from mass conservation principles and some elementary hypothesis related to chemical reactivity. These sets of ordinary differential equations (ODEs) are basically non-linear, their complexity grows as much increases the number of substances present in the reacting media and can be characterized by a set of phenomenological constants (kinetic rate constants) which contains all the relevant information about the physical system. The determination of these kinetic constants is critical for the design or control of chemical systems from a technological point of view but the non-linear nature of the ODEs implies that there are hidden correlations between the parameters which maybe can be revealed with a identifiability analysis. 相似文献
6.
On the Decay of Turbulence in the 20-Liter Explosion Sphere 总被引:1,自引:0,他引:1
The transient flow field in the standard 20-liter explosion sphere was investigated by means of laser Doppler anemometry.
Velocities were measured at various locations within the flow field, and this information was used to quantify the transient
behavior of the root-mean-square of the velocity fluctuations and to investigate the spatial homogeneity and the directional
isotropy of the turbulence. The investigation involved the transient flow fields generated by the three most widely used dust
dispersion systems, namely, the Perforated Dispersion Ring, the Rebound Nozzle, and the Dahoe Nozzle. With all three dispersion
dust devices, the decay of turbulence could be correlated by a decay law of the form
It was found that no formal cube-root-law agreement exists between the 20-liter explosion sphere and the 1-m3 vessel. The results of this work also call into question the widely held belief that the cube-root-law is a valid scaling
relationship between dust explosion severities measured in laboratory test vessels and the severity of industrial dust explosions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
P. Anselmo-Filho S. Hochgreb R.S. Barlow R.S. Cant 《Proceedings of the Combustion Institute》2009,32(2):1763-1770
Combustion under stratified conditions is common in many systems. However, relatively little is known about the structure and dynamics of turbulent stratified flames. Two-dimensional imaging diagnostics are applied to premixed and stratified V-flames at a mean equivalence ratio of 0.77, and low turbulent intensity, within the corrugated flame range. The present results show that stratification affects the mean turbulent flame speed, structure and geometric properties. Stratification increases the flame surface density above the premixed flame levels in all cases, with a maximum reached at intermediate levels of stratification. The flame surface density (FSD) of stratified flames is higher than that of premixed flames at the same mean equivalence ratio. Under the present conditions, the FSD peaks at a stratification ratio around 3.0. The FSD curves for stratified flames are further skewed towards the product side. The distribution of flame curvature in stratified flames is broader and more symmetric relative to premixed flames, indicating an additional mechanism of curvature generation, which is not necessarily due to cusping. These experiments indicate that flame stratification affects the intrinsic behaviour of turbulent flames and suggest that models may need to be revised in the light of the current evidence. 相似文献
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