Phototransduction and light-iinducted mitochondrial activation in blowfly compound eyes

The present thesis considered two aspects of phototransduction in the blowfly Calliphora vicina mutant chalky. First, we studied the mechanism of the basis process, conversion of light to an electrical signal. And second, we examined the light-induced actvation of mitochrondial respiration, necessary to support phototransduction. Zie: Summar

The effect of potassium addition to Pt supported on YSZ on steam reforming of mixtures of methane and ethane

The influence of potassium addition on Pt supported on yttrium-stabilized zirconia (YSZ) was studied with FT-IR CO adsorption and CO-FT-IR-TPD, in order to understand the effect of potassium on the performance of the catalyst in reforming of mixtures of methane and ethane. Potassium modification of PtYSZ strongly influenced the conversion and rate determining steps in methane and ethane in steam reforming. Water activation is the rate determining step on PtYSZ, resulting in high surface coverage of hydrocarbon fragments during steam reforming of mixtures of methane and ethane. This led to blocking of active sites by ethane fragments and consequently low conversion of methane. If potassium is added to the catalyst, hydrocarbon activation on Pt is rate determining, resulting in low surface coverage of methane and ethane. As a result, competition effects of methane and ethane diminished on potassium modified PtYSZ, enabling simultaneous conversion of methane and ethane. The weakening of the interaction of the hydrocarbons with the Pt surface as a result of potassium addition is supported by the fact that the interaction with CO is weakened, as observed with FT-IR-TPD

Effects of Morphology of Cerium Oxide Catalysts for Reverse Water Gas Shift Reaction

Reverse water gas shift reaction (RWGS) was investigated over cerium oxide catalysts of distinct morphologies: cubes, rods and particles. Catalysts were characterized by X-ray diffraction, Raman spectroscopy and temperature programmed reduction (TPR) in hydrogen. Nanoshapes with high concentration of oxygen vacancies contain less surface oxygen removable in TPR. Cerium oxide cubes exhibited two times higher activity per surface area as compared to rods and particles. Catalytic activity of these nanoshapes in RWGS reaction exhibited a relation with the lattice microstrain increase, however a causal relationship remained unclear. Results presented in this study suggest that superior catalytic activity of ceria cubes in RWGS originates from the greater inherent reactivity of (100) crystal planes enclosing cubes, contrary to less inherently reactive (111) facets exposed at rods and particles