N diffusion coefficient

If the diffusion matrix is a diagonal matrix, D = diaglDj,..., D ), then D is just the geometric mean of the n diffusion coefficients. We write D as... 

For large n, diffusion coefficient D is related to x by Einstein s equation. 

Rice, M. E., Gerhardt, G. A., Hierl, P. M., Nagy, G., Adams, R. N., Diffusion-coefficients of neurotrans-mitters and their metabolites in brain extracellular fluid space. Neuroscience 1985, 15(3), 891-902. 

As to donor dopants, only the diffusion of N, O, and Li has been investigated (see Fig. 9 and Table 8). The uncertainty in N diffusion coefficients is caused by problems of measurement due to their low values. For instance, the N diffusion coefficient at 2550°C is about 10-12 cm Vs. 

Umesi, N.O. (1980), Diffusion coefficients of dissoived gases in iiquids -Radius of gyration of solvent and solute . M.S. Thesis, The Pennsylvania State University, PA. 

Note that the effective diffusion coefficient relating N and dc /dz in... 

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. 

Assuming that Eq. (2.67) applies to small molecules in the limit as n 1, calculate To, using D = 3 X 10" m sec" for a typical low molecular weight molecule. Use this value of Tq to estimate t for a polymer with n = 10. Based on Eq. (2.63), evaluate diffusion coefficient for bulk... 

Humidity does not affect the permeabihty, diffusion coefficient, or solubihty coefficient of flavor/aroma compounds in vinyhdene chloride copolymer films. Studies based on /n j -2-hexenal and D-limonene from 0 to 100% rh showed no difference in these transport properties (97,98). The permeabihties and diffusion coefficients of /n j -2-hexenal in two barrier polymers are compared in Table 12. Humidity does not affect the vinyhdene chloride copolymer. In contrast, transport in an EVOH film is strongly plasticized by humidity. 

Umesi, N. O., Coirelating Diffusion Coefficients in Dilute Liquid Mixtures, M.S. Thesis, Penn State University, University Park, PA, 1980. van Velzen, D., R. L. Cardozo, and H. Langenkamp, Ind. Eng. Chem. Fun-dam., 11 (1972) 20. 

The mobility u-can be taken from Table 2-2 for dilute solutions and is proportional to the diffusion coefficient D. It follows, for the transport of anions and cations of an n-n valent salt, that... 

The scaling dependence of the diffusion coefficient on N and Cobs Iso poses a number of questions. While the original scaling predictions, based on reptation dynamics [26,38], oc N, have been verified by some measurements [91,98], significant discrepancies have been reported too [95,96]. Attempts to interpret existing data in terms of alternative models, e.g., by the so-called hydrodynamic scaling model [96], fail to describe observations [100,101]. 

Typical dynamic properties like the scaling of relaxation times, e.g., ri, or diffusion coefficient with N are found in the simulation to change systematically from typical Rouse-like behavior Dj< ocN, t oc to... 

N. C. Bartelt, T. L. Einstein, E. D. Williams. Measuring surface mass diffusion coefficients by observing step fluctuation. Surf Sci 572 411, 1994. 

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