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This paper describes exact solutions to the response of both the elastic and rigid dumbbell models to a steady simple shear flow in a channel having a length scale comparable to the dumbbells themselves. Results are given for rheological properties over the entire range of the ratio of the channel width to the length of the dumbbell. It is found that both models lead to a decrease in viscosity as the channel is reduced in size with the elastic dumbbell predicting a stronger dependence on that parameter compared with the rigid dumbbell. The elastic dumbbell predicts shear independent rheological properties whereas the rigid dumbell predicts shear thinning as in the case of unbounded flows. The rate of shear thinning, however, decreases with decreasing channel width. 相似文献
114.
Structural and electrochemical characterization of 1,3-bis-(4-methylphenyl)imidazolium chloride 总被引:1,自引:0,他引:1
The structure of 1,3-bis(4-methylphenyl)imidazolium chloride was determined and compared to its related imidazole-based carbene. The important structural difference is the greater N2–C2–N3 angle in the salt (109.6°) than in the carbene (101.2°). An electrochemical investigation of the salt revealed a single reduction at –2.32 V in the forward scan and two oxidations at –0.89 and –0.54 V following scan reversal. 相似文献
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C.R. Fuller 《Journal of sound and vibration》1981,75(2):207-228
The transmission of flexural type waves through various discontinuities in the walls of cylindrical shells is investigated. Theoretical curves of transmission loss are obtained for different circumferential wavenumbers and wave types, as functions of frequency. Material stiffness and extensional phase speed, together with the relationship between radial vibration amplitude and total wave power of propagation, are important factors which are found to strongly influence wave transmission through discontinuities. Some practical results useful for predicting the performance of typical pipe isolators (in vacuo) are obtained. 相似文献
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The bonding in closo-boron hydrides, BnH2?n (where n = 5–12), is considered to be the sum of all possible n(n ? 1)/2 boron-boron interactions. The bonding energy u between any pair of boron atoms is taken to depend only upon the internuclear distance d, and to be given by u = 1/d2 ? 1/d. This scheme can be used to rationalize details of molecular geometry and also allows the relative importance of various intramolecular rearrangement pathways to be assessed. This method is compared with alternative approaches to treating the bonding in these molecules. 相似文献
119.
The copper(II) carboxylate-promoted intramolecular carboamination reactions of variously substituted gamma-alkenyl amides have been investigated. These oxidative cyclization reactions efficiently provide polycyclic lactams, useful intermediates in nitrogen heterocycle synthesis, in good to excellent yields. The efficiency of the carboamination process is dependent upon the structure of the amide backbone as well as the nitrogen substituent. 相似文献
120.
Monteux C Kirkwood J Xu H Jung E Fuller GG 《Physical chemistry chemical physics : PCCP》2007,9(48):6344-6350
The mechanical response of particle-laden fluid interfaces is determined by measuring the internal pressures of particle-coated drops as a function of the drop volume. The particle monolayers undergoing compression-expansion cycles exhibit three distinct states: fluid state, jammed state, and buckled state. The P-V curves are compared to the surface pressure isotherms Pi-A that are measured using a Langmuir trough and a Wilhelmy plate on a flat water-decane interface covered with the same particles. We find that in the fluid and jammed states, the water drop in decane can be described by the Young-Laplace equation. Therefore in these relatively low compression states, the bulk pressure measurements can be used to deduce the interfacial tension of the droplets and yield similar surface pressure isotherms to the ones measured with the Wilhelmy plate. In the buckled state, the internal pressure of the drop yields a zero value, which is consistent with the zero interfacial tension measured with the Wilhelmy plate. Moreover we find that the compressibility in the jammed state does not depend on the particle size. 相似文献