Optical density and photonic efficiency of silica-supported TiO2 photocatalysts.

Over the last years, many research groups have developed supported TiO2-based materials in order to improve the engineering applications of photocatalytic technologies. However, not many attempts have been made to evaluate the optical behavior of these materials. This work focuses on the study of the photonic efficiencies of silica-supported TiO2 photocatalysts following the photodegradation of dichloroacetic acid (DCA) as model compound. Catalysts with different types of silica support and titania loadings were tested and their activity was found to be in correlation with the results of the clusters size distribution of the TiO2 nanocrystals. The photonic efficiency of the supported photocatalysts depends extremely on the optical density of the solid suspensions. Influence of the textural properties of the support and the titania loading on the optical density as well as on the photonic efficiency of the materials are discussed. The dependence of the absorption of radiation by the suspension on the catalyst concentration is also analyzed.

Photocatalytic water treatment: fundamental knowledge required for its practical application.

This review attempts to present a state-of-the art overview of the underlying principles of photocatalysis that should not be neglected when designing pilot-scale facilities. In particular, the roles and properties of the primary charge carriers generated upon bandgap illumination within a photocatalyst particle, i.e. valence band hole and conduction band electron, are discussed. The chemical nature of the primary oxidant is critically assessed.

Safety of ponazuril 15% oral paste in horses.

Ponazuril, a triazine-derivative compound, is proposed as a treatment for equine protozoal myeloencephalitis caused by Sarcocystis neurona. Ponazuril 15% oral paste was administered to 24 horses at 0, 10, or 30 mg/kg body weight for either 28 or 56 days, representing zero, two, and six times the proposed dosage rate and one and two times the recommended duration of treatment, respectively. Serum chemistry analysis, coagulation profile, and hematology measurements were performed weekly and necropsy evaluations, including histopathology, were conducted for all animals at the end of the study. Minimal reactions were noted during the treatment period. Soft stools were observed in four of 16 treated horses and three of eight control animals. Serum blood urea nitrogen levels increased and serum sodium levels decreased in horses receiving 10 mg/kg; however, these changes were not associated with number of days on treatment and no value for either variable was outside the normal reference range. No signs of colic were observed in any treated animal during the study. At necropsy, uterine edema was noted in three of the four mares treated with ponazuril at 30 mg/kg. No other treatment-related postmortem or histologic abnormalities were identified in any of the horses. These findings suggest that ponazuril has minimal toxic potential when dosed at levels up to six times the recommended clinical dosage and for one or two times longer than the recommended duration.