The quasi-elastic neutron scattering (QENS) technique was first used to derive self-diffusivities of hydrocarbons in zeolites, but transport diffusivities of deuterated molecules and of molecules which do not contain hydrogen atoms can now be measured. The technique allows to probe diffusion over length scales ranging from an Å to hundreds of Å. The mechanism of diffusion can thus be followed f...

To modify water absorption properties of bamboo fiber (BF) and high density polyethylene (HDPE) composites, heat treatment of BFs was performed prior to compounding them with HDPE to form the composites. The moisture sorption property of the composites was measured and their diffusion coefficients (Dm) were evaluated using a one-dimensional diffusion model. Moisture diffusion coefficient values...

The dissolution of polymer-coated, controlled-release urea fertilisers by means a simple, Fickian diffusion-based model is described. This in contrast to prior contributions that invoke non-Fickian mechanisms or take more quantitative view. Within quasi-static approximation, simple expressions for the granule radius and release profile as function time are obtained terms experimentally accessib...

1. Introduction The growing interest in the application of one-dimensional (1D) molecular sieves both as solid catalysts and selective adsorbents has stimulated considerable attention in the study of diffusive transport of guest molecules in the 1D pores. It has been established that normal Fickian diffusion is not necessarily applicable to describe the diffusion mechanism of guest-host interac...

In a recent study, Chen and Liu [Comput. Phys. Comm. 150 (2003) 31] considered a one-dimensional, linear non-Fickian diffusion problem with a potential field, which, upon application of the Laplace transform, resulted in a second-order linear ordinary differential equation which was solved by means of a control-volume finite difference method that employs exponential shape functions. It is firs...

Numerical evidence of nondiffusive transport in three-dimensional, resistive pressure-gradient-driven plasma turbulence is presented. It is shown that the probability density function (pdf) of tracer particles' radial displacements is strongly non-Gaussian and exhibits algebraic decaying tails. To model these results we propose a macroscopic transport model for the pdf based on the use of fract...