Model Predictive Anti-Surge Control of Centrifugal Compressors with Variable-Speed Drives

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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 environmental‐friendly bacterial cellulose (BC) by using the sol‐gel 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 CCZ−A synthesized by ethanol‐gel exhibits better catalytic activity than the CCZ−W synthesized by water‐gel, 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 water‐gel and ethanol‐gel. The activity of CCZ‐SW synthesized by water‐gel using BC with sugar is obviously higher than that of CCZ−W and CCZ−A. The temperature of complete degradation of toluene over CCZ‐SW is 205 °C, which is 35 °C lower than that of CCZ−W. The results from BET, Raman and H2‐TPR indicate that the larger the specific surface area, the more oxygen vacancies and better low‐temperature reducibility, that are mainly responsible for the excellent activity of CCZ‐SW. The existence of sugar in BC could hinder the agglomeration of active metal particles during the calcination process. Combined with the results of in 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.

Demonstrating coprophagy with passage markers? The example of the plains viscacha (Lagostomus maximus)

Coprophagy, or the ingestion of a certain fraction of the faeces, is a well-known strategy of small herbivores. However, the question of whether a particular species actually uses this cryptic strategy or not is not easily answered experimentally. In this study we introduce the use of ingesta passage markers as a tool to verify coprophagy in species where individual observation might be difficult. In two captive adult plains viscachas (Lagostomus maximus), we demonstrate recurrent excretion peaks for both a fluid (cobald-EDTA) and a particle (chromium-mordanted fibre) marker, the most parsimonious explanation for which is faeces re-ingestion. In addition, a literature review of graphical presentations of passage marker excretion revealed such recurrent marker peaks in a large number of studies; however, these observations were rarely explicitly contributed to a coprophagic digestion strategy. The widespread use of semi-logarithmic plots or cumulative marker excretion curves in displaying passage studies makes recurrent marker excretion peaks less evident. We conclude that passage markers offer a comparatively easy way of assessing the incidence of coprophagy. Due to the reported absence of coprophagy in rabbits, a species well-known for using this strategy, on high-protein, low-fibre diets, it is recommended that investigations of the occurrence of coprophagy should be made with animals fed challenging, high-fibre diets

Transgenic mice overexpressing XIAP in neurons show better outcome after transient cerebral ischemia

Copyright 2003 ACADEMIC PRESS INC ELSEVIER SCIENC

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