Intrinsic microwave dielectric loss of lanthanum aluminate.

The intrinsic dielectric properties of LaAlO3 were investigated to understand the microwave properties of several materials containing LaAlO3. In this study, LaAlO3 single crystals were prepared by the Czochralski method. The temperature dependence of the dielectric properties and neutron inelastic scattering of the single crystals were measured. From these data, the intrinsic dielectric properties were evaluated and it was found that the dielectric loss of the LaAlO3 includes two types of dielectric loss. One is a phonon absorption-related loss and the other is a component of the loss arising from Debye- type orientation polarization. The latter affects the room temperature dielectric loss in materials containing LaAlO3. The present study suggests that avoiding this polarization loss is an important goal in decreasing the total dielectric loss.

Observation of hydrogen in deuterated methane hydrate by maximum entropy method with neutron powder diffraction.

The crystal structure of deuterated methane hydrate (structure I, space group: Pm(-)3n) was investigated by neutron powder diffraction at temperatures of 7.7-185 K. The scattering amplitude density distribution was examined by a combination of Rietveld method and maximum entropy method (MEM). The distribution of the D atoms in both D(2)O and CD(4) molecules was clarified from three-dimensional graphic images of the scattering amplitude density. The MEM results showed that there were low-density sites for the D atom of D(2)O in a particular location within the D(2)O cage at low temperatures. The MEM provided more reasonable results because of the decrease in the R factor that is attainable by this method. Accordingly, the low-density sites for the D atom of D(2)O probably exist within the D(2)O cage. This suggests that a spatial disorder of the D atom of D(2)O occurs at these sites and that hydrogen bonds between D(2)O molecules become partially weakened. With regard to the CD(4) molecules, there were high-density sites for the D atom of CD(4), and the density distribution of the C and D atoms was observed separately in the scattering amplitude density image. Consequently, the C-D bonds of CD(4) were not observed clearly because the CD(4) molecules had an orientational disorder. The D atoms of CD(4) were displaced from the line between the C and O atoms, and were located near the face center of the polygon in the cage. Accordingly, the D atoms of CD(4) were not bonded to specific O atoms. This result is consistent with the hydrophobicity of the CD(4) molecule. We also report the difference between the small and the large cages in the density distribution map and the temperature dependence of the scattering amplitude density.

Clinical features of liver disturbance in rheumatoid diseases: clinicopathological study with special reference to the cause of liver disturbance.

BACKGROUND: Liver disturbance in rheumatoid diseases results not only from liver disease associated with the rheumatoid diseases themselves but also from various other causes. This study aimed to elucidate the clinical features of liver disturbance in rheumatoid diseases, focusing on the cause of this disturbance. METHODS: A clinicopathological study was performed in 306 patients (106 with systemic lupus erythematosus, 71 with Sjögren's syndrome, 59 with rheumatoid arthritis, 27 with scleroderma, 30 with polymyositis, and 13 with polyarteritis nodosa). RESULTS: Liver disturbance occurred in 43% of these patients and resulted from various causes. Its degree and duration varied from one cause to another. Liver disease associated with rheumatoid diseases was the leading cause of the liver disturbance in these patients and was characterized by mild and transient liver disturbance (maximum alanine aminotransferase [ALT] level during the study period, 68 +/- 8 IU/ml; maximum alkaline phosphatase [ALP] level, 410 +/- 31 IU/ml; duration of liver disturbance, 6 +/- 2 months). Most patients with this type of liver disease showed minimal change in liver histology, although two-thirds of those evaluated by the international scoring system for autoimmune hepatitis (AIH) were classified as "probable" or "definite". Eight of 14 patients with histologically proven chronic hepatitis or cirrhosis were infected with hepatotropic virus (7 with hepatitis C virus [HCV] and 1 with hepatitis B virus [HBV]). Five of 9 patients in whom the hepatic lesion progressed had hepatotropic virus infection (4 with HCV and 1 with HBV), and the other 4 patients suffered from autoimmune liver diseases. CONCLUSIONS: Liver disease associated with rheumatoid diseases was the leading cause of liver disturbance in these patients and was characterized by mild and transient liver disturbance, whereas progressive liver diseases were often associated with hepatotropic virus, mainly HCV, or autoimmune liver diseases. Liver histology is indispensable for differentiating AIH from liver disease associated with rheumatoid diseases.