Te–Ge reactive diffusion has been studied by in situ XRD, TEM, and atom probe tomography a sample made of poly-Te layer deposited on an amorphous Ge layer, compared to the reverse case a-Ge layer.

Diffusion is interesting because it is slow. As a result, many studies of diffusion seek ways to make the process fast and selective. For example, most membrane separations use thin polymer films to recover particular chemicals. Nitrogen is separated from air, and water is purified by ultrafiltration. This is an active and important area of diffusion research. However, in other cases, we may se...

Cross-diffusion, the phenomenon in which a gradient in the concentration of one species induces a flux of another chemical species, has generally been neglected in the study of reaction-diffusion systems. We summarize experiments that demonstrate that cross-diffusion coefficients can be quite significant, even exceeding "normal," diagonal diffusion coefficients in magnitude in systems that invo...

We propose a new conceptual model of fractureflow-enhanced matrix diffusion, which correlates with fracture-flow velocity, i.e., matrix diffusion enhancement induced by rapid fluid flow within fractures. According to the boundary-layer or film theory, fracture flow enhanced matrix diffusion may dominate mass-transfer processes at fracture-matrix interfaces, because rapid flow along fractures re...

Compaction in reactive porous media is modelled as a reaction-diffusion process with a moving boundary. Asymptotic analysis is used to find solutions for the coupled nonlinear compaction equations, and a traveling wave solution is obtained above the reaction zone.

Reaction diffusion systems are extremely useful for studying pattern formation in biological systems. We carry out a Lorenz like few mode truncation of a reaction diffusion system and show that it not only gives the same qualitative behaviour as the more complicated systems but also indicates of the existence of a Hopf-bifurcation in the turing region. PACS. 87.10.+e General theory and mathemat...