Synthesis of bulk, dense, nanocrystalline yttrium aluminum garnet from amorphous powders

Amorphous powders of Al2O3x2014;37.5 mol% Y2O3 (yttrium aluminum garnet (YAG)) were prepared by coprecipitation, decomposed at 800xB0;C, and hot-pressed uniaxally at low temperature (600xB0;C) and a moderate pressure (750 MPa). Optimum conditions yielded microstructures with only 2% porosity and partial crystallization of YAG. Further processing using high quasi-hydrostatic pressure (1 GPa) at 1000xB0;C enabled the production of fully crystallized YAG with gt;96% relative density and a nanocrystalline grain size of x223C;70 nm. 13

Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 3: Energy Conversion subsystems and components. Part 2: Primary heat input systems and heat exchangers

Primary heat input systems and heat exchangers were evaluated for advanced energy conversion systems. Results are presented and discussed

Liver Allograft: Its Use in Chronic Active Hepatitis with Macronodular Cirrhosis, Hepatitis B Surface Antigen

A patient suffering from chronic active hepatitis with macronodular cirrhosis, positive for hepatitis B surface antigen (HBsAg), was treated with an orthotopic liver allograft. The HBs antigenemia, as measured with several precipitation tests and by complement fixation, became negative after transplantation and remained so for about 2½ months. During the interval, very low titers of the antigen were detectable by radioimmunoassay. At about three months after transplantation, she had an attack of acute hepatitis, at which time HBsAg became detectable by all tests. She recovered, but progressive liver disease developed during the remaining 1½ years of her life. She died of disseminated nocardiosis and candidiasis with deteriorating hepatic function. The homograft at autopsy showed no evidence of rejection, but was the site of chronic active liver disease, although of a different pathologic pattern than that affecting her native liver. The differences in histology may reflect the influence of chronic immunosuppression on the features of chronic active hepatitis. © 1979, American Medical Association. All rights reserved

The quantized Hall conductance of a single atomic wire: A proposal based on synthetic dimensions

We propose a method by which the quantization of the Hall conductance can be directly measured in the transport of a one-dimensional atomic gas. Our approach builds on two main ingredients: (1) a constriction optical potential, which generates a mesoscopic channel connected to two reservoirs, and (2) a time-periodic modulation of the channel, specifically designed to generate motion along an additional synthetic dimension. This fictitious dimension is spanned by the harmonic-oscillator modes associated with the tightly-confined channel, and hence, the corresponding "lattice sites" are intimately related to the energy of the system. We analyze the quantum transport properties of this hybrid two-dimensional system, highlighting the appealing features offered by the synthetic dimension. In particular, we demonstrate how the energetic nature of the synthetic dimension, combined with the quasi-energy spectrum of the periodically-driven channel, allows for the direct and unambiguous observation of the quantized Hall effect in a two-reservoir geometry. Our work illustrates how topological properties of matter can be accessed in a minimal one-dimensional setup, with direct and practical experimental consequences.

Article and method for making complex shaped preform and silicon carbide composite by melt infiltration

Small diameter silicon carbide-containing fibers are provided in a bundle such as a fiber tow that can be formed into a structure where the radii of curvature is not limited to 10-20 inches. An aspect of this invention is directed to impregnating the bundles of fibers with the slurry composition to substantially coat the outside surface of an individual fiber within the bundle and to form a complex shaped preform with a mass of continuous fibers