With diffusion tensor MRI one has access to the organization in space of tissue microstructural components. This outstanding potential adds, however, another layer of complexity to the diffusion MRI data acquisition and analysis processes. Over the last few years many articles have been published dealing with those matters. This special issue is thus timely to provide readers with the synthesis...

We start from the many-chain Smoluchowski equation that describes dynamics of dense polymer solutions and derive an effective diffusion equation for a tagged ~probe! chain distribution function. In the tagged chain diffusion equation the effects of the inter-chain interactions are incorporated through an effective friction tensor. We propose a simple phenomenological formula for the friction te...

A new modified diffusi on coefficient (MDC) technique for solv ing conve ction diffusion equation is proposed. The Galerkin finite-element discretization process is applied on the modified equation rather than the original one. For a class of one-dimensional convec-tion–diffusion equations, we derive the modi fied diffusion coefficient analytically as a function of the equation coefficients and...

Diffusion filters are widely used to reduce noise on images. In [1] a new diffusion method for image filtering based on incorporating an integral of image intensity over a point neighborhood into the diffusion coefficient was suggested. Here we start by introducing two modified diffusion filters. Next we illustrate on number of images the advantages of modified filters comparing with not modifi...

The equilibrium partition coefficient (K) and diffusion coefficient (Dgel) of two proteins and two linear polymers were measured as a function of polymer content of a 2.7% cross-linked polyacrylamide (PA) gel. The gel concentration, expressed as a volume percentage of PA in the gel (phi), varied between 0 and 14%. The measurements were made by fluorescence spectroscopy; fluorescent dyes were co...

Electrochemical impedance spectroscopy (EIS) was used to measure the solid-state diffusion coefficient of protons in nickel hydroxide films at room temperature as a function of state of charge (SOC). A model for the complex faradaic impedance of the nickel hydroxide active material is presented and used to extract the diffusion coefficient of protons from the EIS data. Impedance data over a ran...

The diffusive motion of foreign particles dispersed in a premelting solid is analyzed within the framework of irreversible thermodynamics. We determine the mass diffusion coefficient, thermal diffusion coefficient and Soret coefficient of the particles in the dilute limit, and find good agreement with experimental data. In contrast to liquid suspensions, the unique nature of premelting solids a...

An investigation of the drying of spherical food particles was performed, using peas as the model material. In the development of a mathematical model for drying curves, moisture diffusion was modelled using Fick’s second law for mass transfer. The resulting partial differential equation was solved using a forward-time central-space finite difference approximation, with the assumption of variab...