Collective diffusion

If a steady systematic motion is imposed, those topological arrangements which present barriers to configuration relaxation will come into play. As in dilute solutions the chains are continually drawn into a disturbed distribution of configurations by the external motions and respond by diffusing collectively toward an equilibrium distribution. In concentrated systems each chain must... 

As with diffusion, the same behavior with particle radius is found for the spherical and cylindrical collection efficiencies. This is again a consequence of the similarity of the velocity fields near the collector surfaces. However, in contrast to the diffusion collection efficiency, which decreases with increasing particle radius as the interception collection efficiency increases with... 

Electron Transport 2.1.5.3.1 Electron Diffusion, Collection, and Recombination A unique feature of a porous photoelectrochemical system is the permeation of the solid semiconducting network by an electrolyte solution on a scale smaller than Lmin (Fig- 17b). As a result, one of the photogenerated charge carriers can be transferred to the solution. In the following, we will assume that the hole is transferred to the electrolyte solution and oxidizes a reduced species. Photogenerated electrons are left in the... 

A final geometry exists for directional illumination, diffuse collection integrating sphere measurements. The 30/T geometry (30° incidence, total hemispherical collection) is specified by the American Society for Testing and Materials (ASTM) for the measurement of acoustical ceiling tile reflectance, The author knows of no other applications that specify this integrating sphere geometry. 

Binder K 1983 Collective diffusion, nucleation, and spinodal decomposition in polymer mixtures J. Chem. Phys. 79 6387... 

Ifihe Bath relaxation con start t, t, is greater than 0.1 ps. yon should be able Lo calculate dyriani ic p roperlies, like time correlation fun c-tioris and diffusion constants, from data in the SNP and/or C.SV files (sec "Collecting Averages from Simulations"... 

Monte Carlo simulations require less computer time to execute each iteration than a molecular dynamics simulation on the same system. However, Monte Carlo simulations are more limited in that they cannot yield time-dependent information, such as diffusion coefficients or viscosity. As with molecular dynamics, constant NVT simulations are most common, but constant NPT simulations are possible using a coordinate scaling step. Calculations that are not constant N can be constructed by including probabilities for particle creation and annihilation. These calculations present technical difficulties due to having very low probabilities for creation and annihilation, thus requiring very large collections of molecules and long simulation times. 

Figure 5 relates N j to collection efficiency particle diffusivity from Stokes-Einstein equation assumes Brownian motion same order of magnitude or greater than mean free path of gas molecules (0.1 pm at... 

The diffusion and solubihty coefficients for oxygen and carbon dioxide in selected polymers have been collected in Table 5. Determination of these coefficients is neither common, nor difficult. Methods are discussed later. The values of S for a permeant gas do not vary much from polymer to polymer. The large differences that are found for permeabihty are due almost entirely to differences in D. 

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