Surface properties and photocatalytic activity of Pt core/Ag shell nanoparticle-loaded TiO2.
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Journal Article↗
Biomedical subjects
Ayako Takao
Publications and source records attributed to Ayako Takao.
Kinetic and DFT studies on the Ag/TiO2-photocatalyzed selective reduction of nitrobenzene to aniline.
TiO2 particles loaded with silver nanoparticles with a mean diameter of 1.5 nm exhibit a high photocatalytic activity (84 % conversion after 1 h irradiation) for the reduction of nitrobenzene to aniline with 100 % selectivity in the presence of CH3OH (concentration=100 mM). High-resolution transmission electron microscopic studies of Pt-photodeposited Ag/TiO2 demonstrate that the Ag nanoparticles act as reduction sites in the photocatalytic reaction. Both spectroscopic measurements and density functional theory (DFT) calculations reveal that nitrobenzene is selectively adsorbed onto the Ag surfaces of Ag/TiO2 via partial electron transfer from Ag to nitrobenzene, whereas the interaction between aniline and Ag/TiO2 is weak. The kinetic analysis indicates that the recombination between the electrons flowing into the Ag nanoparticle and the holes left in the TiO2 valence band is significantly suppressed, particularly in the presence of CH3OH. The high activity and selectivity in the present Ag/TiO2-photocatalyzed reduction are rationalized in terms of the charge separation efficiency, the selective adsorption of the reactants on the catalyst surfaces, and the restriction of the product readsorption.
Aniline Compounds↗
Drastic enhancement of TiO2-photocatalyzed reduction of nitrobenzene by loading Ag clusters.
Ag clusters (mean diameter = 1.5 nm, standard deviation = 0.37 nm) were photodeposited on TiO(2) particles in a highly dispersed state. The loading of a small amount of the Ag clusters (0.24 wt %) dramatically enhanced both the activity for the TiO(2) photocatalytic reduction of nitrobenzene and the product selectivity of aniline. The essential action mechanism of the Ag clusters is discussed.
Absorption↗
[Phenotypic variation in Actinobacillus actinomycetemcomitans].
OBJECTIVE: To investigate the colony variation in Actinobacillus actinomycetemcomitans (Aa) from rough to smooth and recognize its different morphology during laboratory translations. METHODS: Primary strains isolated from subgingival plaque of two juvenile periodontitis patients were repeatedly subcultured on agar plates and broth; for broth culture, every generation was translated in broth and on solid medium separately to observe the corresponding morphologies of Aa grow in broth. RESULTS: Three smooth strains of Aa from the broth culture were obtained. The process was about 7-8 generations: colonies changed from a small and adherence phenotype to a bigger and sediment ones and finally the culture supernatant became turbid; the corresponding morphologies grow on agar exhibiting an adherent, small rough colony phenotype which had a star-shaped internal structure converted gradually to a kind of bigger, opaque, nonadherent, smooth phenotype, then the colony extended out from the margin of the colony and finally converted to a flat, almost parent morphology and the same time the star-like inner structure converted to a simpler and smaller type and finally disappeared. We could not get completely smooth variants of Aa from agar. CONCLUSIONS: The variation in colony morphology of Aa from rough to smooth is a process, in which the colony was gradually wetter and bigger and at the same time gradually lost the inner structure. During this process three colony morphologies at least can be seen, including rough, opaque smooth and almost translucent smooth.
Aggregatibacter actinomycetemcomitans↗