The development of cement and concrete additive

The present work attempted to utilize xylose by converting it to an aldonic acid. In the present study, xylose was converted to xyloni acid by using commercial glucose oxidase enzyme, palladium catalysis, and microbial bioconversion. The enzyme conversion was successfully done using a commercial glucose oxidase. The microbial conversion with Gluconobactor oxydans proceeded even with the presence of a large amount of lignosulfonate. Thus obtained xylonic acid products were evaluated as a cement dispersing agent in cement and concrete tests. It was found that xylonic acid is approximately twice as effective as lignosulfonate. Xylonic acid can be effectively utilized in concrete water reducer application. A part of the work was presented at American Chemical Society Annual Meeting at Anaheim in 2004.     

THE DESIGN AND IN VITRO RELEASE CHARACTERIZATION OF HUMAN CROSS-LINKED HAEMOSLDBIN MICROCAPSULES CONTAINING DOXORUBICIN FOR POTENTIAL CHEMOEMBOLIZATION USE

Cross-linked human haemoglobin microcapsules were prepared by reacting native haemoglobin with terephthaloyl chloride using an interfacial polymerization process. Low cross-linking agent concentration, and short time reaction produced weakly cross-linked microcapsules which incorporated 707. of the doxorubicin by adsorption from aqueous solution. Only small amounts of doxorubicin were released from the microcapsules in distilled water over 24 hours. However, the presence of electalytes in the aqueous sink solution altered profoundly the release profile of doxorubicin and significantly increased the release rate of the drug. These results suggest that there was a competitive fixation of the cation an the binding sites, identified as carboxyl groups available to the drug molecules. Release profile of doxorubicin from the microcapsules was analyzed according to kinetic models using the non-linear regression search procedure. Doxorubicin release from the microcapsules was found to be controlled by an ion-exchange particle diffusion process. This was confirmed by the “interruption test” which is considered the best technique for distinguishing between particle and film diffusion controlled kinetic process     

The development of cement and concrete additive

The present work attempted to utilize xylose by converting it to an aldonic acid. In the present study, xylose was converted to xyloni acid by using commercial glucose oxidase enzyme, palladium catalysis, and microbial bioconversion. The enzyme conversion was successfully done using a commercial glucose oxidase. The microbial conversion with Gluconobactor oxydans proceeded even with the presence of a large amount of lignosulfonate. Thus obtained xylonic acid products were evaluated as a cement dispersing agent in cement and concrete tests. It was found that xylonic acid is approximately twice as effective as lignosulfonate. Xylonic acid can be effectively utilized in concrete water reducer application.     

Determination of Copper in Mineral Waters from Galicia, Spain, by Flame Atomic Absorption Spectrometry Using Preconcentration with Diethyldithiocarbamate Loaded on Silica Gel

Solid phase extraction using sodium diethyldithiocarbamate (DDC) loaded on silica gel has been used for preconcentration of trace amounts of copper from commercial mineral waters prior to its determination by flame atomic absorption spectrometry. The sorption and releasing of copper have been studied under both static and dynamic conditions. A short shaking time is required for quantitative sorption using the batch method, and a high flow-rate (6 ml min⁻¹) can be used in the column method due to the fast sorption and desorption kinetics. The copper concentration found in several mineral waters from Galicia (Spain) ranged from 8.4 to 23.8 μg L⁻¹. There were no significant differences between the solid-phase extraction method and the conventional solvent extraction method which uses DDC as chelating agent.