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...

Due to the fact that many application processes take place at different temperature, better examining and understanding of swelling properties as a function of temperature is essential for such application. The temperature effect on the swelling properties of commercial polyacrylic acid (PAA) hydrogel beads was investigated as a function of time and temperature. Gel bead size, swelling equilibr...

Due to the fact that many application processes take place at different temperature, better examining and understanding of swelling properties as a function of temperature is essential for such application. The temperature effect on the swelling properties of commercial polyacrylic acid (PAA) hydrogel beads was investigated as a function of time and temperature. Gel bead size, swelling equilibr...

The effect of ionic and non-ionic excipients and additives as modulators of swelling and erosion kinetics and verapamil HCl release from guar-based matrix tablets was investigated. Tablet dissolution, erosion and water uptake studies were carried out using a modified USP 23 Apparatus 2 method. The kinetics of gel strength and texture development were studied by textural analysis. Near linear dr...

A fractional step numerical method is developed for the nonlinear partial differential equations arising in chemotaxis models, which include density-dependent diffusion terms for chemotaxis, as well as reaction and Fickian diffusion terms. We take the novel approach of viewing the chemotaxis term as an advection term which is possible in the context of fractional steps. This method is applied t...

This paper investigates whether spontaneous, stationary velocity fluctuations can lead to deviations from the regular Fickian diffusion. A kinematic analysis reveals that anomalous diffusion, both fast and slow, arises from long-tailed velocity auto-correlation functions (VACF). This infinite span of interdependence of the random velocity leads to the breakdown of the central limit theorem for ...

The diffusion behavior of interacting particles determines the behavior of a large number of systems ranging from pedestrians crossing a road to ions passing through channels in living cells. Here we present a system in which the nature of the diffusion process varies with changes in the external conditions. We find this special behavior in a colloidal model system, consisting of micron sized p...

Thymol, an important and advantageous component of many essential oils, has been applied as an antimicrobial agent in animals. To increase the duration of action of this compound in ruminants, it was decided here to prepare a controlled release carrier for thymol. Hydroxy propyl methyl cellulose (HPMC) and ethyl cellulose (EC) were used as the matrix polymer here. Mixtures of thymol with eight ...