Finite difference modeling of the gas transport process in glassy polymers

Finite difference modeling has been used to predict the results of gas transport experiments for a concentration-dependent diffusion coefficient. Experiments on the transport of CO₂ in poly(ethylene terephthalate) and poly(ethylene naphthalate) had previously shown a difference between the effective diffusion coefficients for absorption and desorption runs of a double-sided experiment, but this effect had not been seen for single-sided experiments. The finite difference calculations show that such results are to be expected, and the parameters included in the models that attempt to describe the diffusion process in glassy polymers, such as the dual-mode model, and which lead to concentration-dependent diffusion coefficients, can be found by fitting the experimental data for the double-sided experiment using finite difference modeling. The dependence of the effective diffusion coefficient on pressure for the single-sided experiment can be correctly predicted using results from the double-sided experiment for an identical sample. © 1996 John Wiley & Sons, Inc.     

Transmutation: Towards solving problem of spent nuclear fuel

An Accelerator Driven Subcritical System (ADS) is a promising, new concept for transmutation of long-lived isotopes originating from spent nuclear fuel. In the mainstream of research is the proton accelerator-driven ADS, however, on smaller scale an electron accelerator-driven machine could be an alternative. Using international codes we started to investigate the reactor physical aspects of such a device. In our paper we present the results of the first step of the modelling: the target optimization.     

TLC Analysis of the In-Vitro Reaction of Beech (Fagus sylvatica L.) Wood Enzyme Extract with Catechins

JPC – Journal of Planar Chromatography – Modern TLC - The factors affecting the economically and sylviculturally disadvantageous formation of red heartwood in beech are only partly...