Hydrothermal Synthesis of Yttria-Stabilized Zirconia Nanocrystals with Controlled Yttria Content.

In this study, we demonstrate for the first time the hydrothermal synthesis of yttria-stabilized zirconia (YSZ) nanocrystals with controlled yttria content (x = 3-12 mol %; xYSZ) with negligible aggregation from aqueous solution. The nanocrystals were grown via the hydrothermal treatment of basic Zr(IV) and Y(III) carbonate complex aqueous solutions in the presence of a cationic ligand, N(CH3)4(+). The nanocrystals were characterized in detail by dynamic light scattering, ζ-potential measurement, X-ray diffraction, specific surface area measurement based on the Brunauer-Emmett-Teller theory, transmission electron microscopy, energy dispersive X-ray spectroscopy, and Raman spectroscopy.

Deoxycholic acid formation in gnotobiotic mice associated with human intestinal bacteria.

In humans and animals, intestinal flora is indispensable for bile acid transformation. The goal of our study was to establish gnotobiotic mice with intestinal bacteria of human origin in order to examine the role of intestinal bacteria in the transformation of bile acids in vivo using the technique of gnotobiology. Eight strains of bile acid-deconjugating bacteria were isolated from ex-germ-free mice inoculated with a human fecal dilution of 10(-6), and five strains of 7alpha-dehydroxylating bacteria were isolated from the intestine of limited human flora mice inoculated only with clostridia.