17 research outputs found
Studies on CuCe0.75Zr0.25Ox preparation using bacterial cellulose and its application in toluene complete oxidation
A series of CuCe0.75Zr0.25Ox catalysts (CCZ) were synthesized based on the environmentalâfriendly bacterial cellulose (BC) by using the solâgel method. The corresponding synthesis mechanism, physicochemical properties of the catalysts and catalytic performances for toluene oxidation were comprehensively studied. In the presence of BC without sugar, the CCZâA synthesized by ethanolâgel exhibits better catalytic activity than the CCZâW synthesized by waterâgel, which may be due to the different roles of BC in different solvents. However, it is worth noting that the graft copolymerization between BC and active metal (Ce4+, Cu2+) is the same process in both waterâgel and ethanolâgel. The activity of CCZâSW synthesized by waterâgel using BC with sugar is obviously higher than that of CCZâW and CCZâA. The temperature of complete degradation of toluene over CCZâSW is 205â°C, which is 35â°C lower than that of CCZâW. The results from BET, Raman and H2âTPR indicate that the larger the specific surface area, the more oxygen vacancies and better lowâtemperature reducibility, that are mainly responsible for the excellent activity of CCZâSW. The existence of sugar in BC could hinder the agglomeration of active metal particles during the calcination process. Combined with the results of inâ
situ DRIFT, the adsorbed toluene on the catalyst surface is oxidized into alkoxide, aldehydic and carboxylic acid species as intermediates before the complete oxidation into CO2 and H2O.
Occurrence of cataract and fatty liver in captive plains viscachas (Lagostomus maximus) in relation to diet
An increased incidence of cataract and fatty liver in plains viscachas (Lagostomus maximus) was noted for many years at the Zurich Zoo. Based on elevated serum fructosamine and glucose, diabetes mellitus was diagnosed, and these parameters normalized when the diet of the animals was changed from a low-fiber to a high-fiber diet. Here, we evaluate 177 necropsy reports from before and after the diet change for the incidence of cataracts and fatty liver. Sixteen of 56 animals (29%) that were born before the diet change developed cataract. In contrast, only two of 121 animals (1.65%) that were born after the diet change developed cataracts. The prevalence of cataract and fatty liver in animals born after the diet change (1% and 0%, respectively) was significantly lower than in animals born before (9% and 6%, respectively) the diet change. The results suggest that the plains viscachas at Zurich Zoo were affected by an alimentary induced diabetes mellitus (type 2) before the diet was changed