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The bed depth service time (BDST) design model, which accounts for the change of bed adsorption capacity with service time, has been modified to expand its application and overcome the limiting assumptions of the original BDST analysis. Column experiments were undertaken to test the new model for two adsorption systems, namely zinc ion-bone char and Acid Blue 80 dye-activated carbon. It was found that the percentage of saturation capacity could be correlated using a square-root dependence on the service time and this correlation was incorporated into the original BDST analysis to replace the total sorption capacity term, giving the model a much wider application to real systems. The empty bed residence time optimization approach was modified using the same time-dependent capacity expression and was successfully applied to the metal ion-bone char and the dye-activated carbon system with the use of equilibrium saturated bed capacity. These modifications to the BDST design model and the EBRT optimization model will give more accurate scale-up data for the design of large-scale column adsorption systems.
© 2002 Society of Chemical Industry

Oral gavage of pregnant C57BL/6J mice with N, N1-bis(dichloroacetyl)-1,8-octa-methylene diamine on day 10 of gestation alters the morphology of a primary lymphoid organ, i.e., thymus, of the offspring when observed at 36 days of postnatal life. Thymuses obtained from the experimental offspring exhibited an overall reduction in size and cortical hypoplasia. Morphology of the spleen, a secondary lymphoid organ, is also affected in the offspring obtained from dams treated with this compound on day 10 of gestation. Spleens exhibited diffusely distributed white pulp areas compared to the distinctly nodular appearance in control spleens. Furthermore, it has been shown for the first time that prenatal administration of N, N1-bis(dichloroacetyl)-1,8-octamethylene diamine on day 12 of gestation alters the functional responsiveness of splenocytes obtained from the offspring of treated dams to a variety of mitogens when examined at 3, 5, 9 and 16 weeks of postnatal life. Administration of the compound prenatally on day 12 of gestation did not alter the postnatal morphological appearance of either thymus or spleen.

The genetic relatedness of 18 human and 29 ovine isolates of Bordetella parapertussis was examined by macrorestriction digestion of DNA with the rarely cutting enzyme XbaI and resolution by pulsed-field gel electrophoresis. There was clear separation of human and ovine isolates and variation within host types. The human isolates were separated into three types as were the 24 Scottish ovine isolates. Species-specific bands were observed with the human isolates at 114, 134, 166, 213, 346 and 372 kb. No species-specific bands were found in the B. parapertussis ovine isolates. Isolates of B. parapertussis recovered from sheep in New Zealand gave a further two DNA banding patterns which were clearly different from the Scottish ovine and the human isolates. These results indicate that human and ovine isolates of B. parapertussis are genetically distinct and that variation exists within isolates from the same host species. Pulsed-field gel electrbphoresis therefore appears to be a powerful discriminatory tool for the classification of B. parapertussis.