The diffusion of fractal aggregates constructed with the method by Thouy and Jullien [J. Phys. A 27, 2953 (1994)] comprised of N(p) spherical primary particles was studied as a function of the aggregate mass and fractal dimension using molecular dynamics simulations. It is shown that finite-size effects have a strong impact on the apparent value of the diffusion coefficient (D), but these can b...

The effects of segment-segment interactions on the static and dynamical properties of model polymer solutions are examined by Brownian dynamics simulations in the free-draining limit over a wide concentration range. A bead-and-spring model is used to describe the polymer chains at a coarse-grained level, in which segment-segment interactions are represented by a bead-bead pair potential with a ...

Time-resolved transmittance spectroscopy was performed in the wavelength range of 610 or 700 to 1050 nm on phantom parallelepipeds and bone tissue cubes of different sizes. The data were best fitted with solutions of the diffusion equation for a laterally infinite slab and for a parallelepiped to investigate how size and optical properties of the samples affect the results obtained with the two...

We consider a two-species simple exclusion process on periodic lattice. use the method of matched asymptotics to derive evolution equations for two population densities in dilute regime, namely cross-diffusion system partial differential species densities. First, our result captures non-trivial interaction terms neglected mean-field approach, including non-diagonal mobility matrix with explicit...

Diffusion magnetic resonance imaging provides a measure of the average distance travelled by water molecules in a medium and can give useful information on cellular structure and structural change when the medium is biological tissue. In this paper, two approximate models for the apparent diffusion coefficient at low b-values and long diffusion times are formulated and validated. The first is a...

In this paper we investigate the m s p o r t proses for rigid spherically symmetric macromolecules, having a segment densiry distribution falling off as rrA. We calculate the rotational and translational diffusion coefficient for P spbaically symmetric polymer and the shear viscosiiy for a dilute suspension of these molecules, s m i n g from a continuum description based on the Debye-Brink" equ...

Measurements of electron transport, effective ionization, and attachment coefficients are reported for C2F4' In addition, measurements of the electron drift velocity and the effective ionization coefficient as a function of the density-reduced electric field E/N are reported for mixtures of C2F4 with Ar. The measured effective ionization coefficients in C2F4/Armixtures indicates a contribution ...

1. Introduction Our understanding of polymer dynamics has greatly improved due to the reptation model and the scaling ideas. [1] According to scaling and reptation theory, the diffusion coefficient in semidilute or concentrated regimes is related to the molar mass and polymer concentration by D ~ M-2 c-1.75 and D ~ M-2 c-3 for good-solvent and θ-solvent conditions, respectively. In a limited ra...

We introduce a simplified expression for the diffusion coefficient (D) of a multicomponent Lattice Boltzmann model. For dilute solutions, this expression is reduced to have dependence only on the molecular mass and relaxation time of the solute. By altering the molecular mass, the value of D can be varied by several orders of magnitude, thus, providing an additional parameter for use in tuning ...