Structure and electrical characteristics of Ce4+-doped Ba2In2O5

The In-site of Ba₂In₂O₅ with Brownmillerite structure was partially substituted for Ce⁴⁺ ions in order to examine the doping effect on the order-disorder transition. Ba₂In_{2 – x} Ce _x O_{5 + x/2} (x = 0.1, 0.2, 0.3, 0.5, 1.0, and 1.5) were prepared by solid state reaction. X-Ray diffraction analyses of these powder samples demonstrated that Ba₂In_{2 – x} Ce _x O_{5 + x/2} (x = 0.1 and 0.2) possesses Brownmillerite structure. With increasing content of Ce⁴⁺ ion the crystal system of Ba₂In_{2 – x} Ce _x O_{5 + x/2} (x = 0.3, 0.5, and 1.0) changed to cubic perovskite structure above the order-disorder transition temperature of Ba₂In₂O₅. Arrhenius plots of the electrical conductivities of Ba₂In_{2 – x} Ce _x O_{5 + x/2} (x = 0.2, 0.3, and 1.0) exhibited no discontinuity. These compounds had high transference numbers of oxide ion above 973 k.     

Selective hydrogenation of oleic acid to 9-octadecen-1-ol: Catalyst preparation and optimum reaction conditions

A new catalyst, ruthenium-tin-alumina is found to selectively hydrogenate oleic acid to 9-octadecen-1-ol (oleyl + elaidyl alcohol) at low pressure with high yield. Catalyst preparation methods, catalyst raw materials and activation conditions have a significant effect on the activity of the catalyst. The optimum atomic ratio of ruthenium to tin is about 1:2. Catalyst prepared by an improved sol-gel method shows higher activity and selectivity than catalysts prepared by impregnation and coprecipitation methods. Chloride is found to have a negative effect on catalytic activity. The best catalyst is prepared from chloride-free ruthenium and tin raw materials. Under the optimum reaction conditions of 250°C and 5.6 MPa, the selectivities for 9-octadecen-1-ol and total alcohol (9-octadecen-1-ol + stearyl alcohol) formation are 80.9% and 97%, respectively, at a conversion of 81.3%.     

Relationship between local immune response to Helicobacter pylori and the diversity of disease: investigation of H. pylori-specific IgA in gastric juice

In order to evaluate the relationship between local immune response to Helicobacter pylori and the diversity of disease, 77 asymptomatic subjects who underwent a health examination were studied. Helicobacter pylori-specific IgG in serum and H. pylori-specific IgA in gastric juice were measured by ELISA, and the measured IgA titre was classified into two grades, low or high. Histological classification of gastritis was performed according to the Sydney system. Cytokines in gastric juice were also measured, and the cytotoxin-associated gene A (cagA) status of H. pylori was tested by PCR. Of the 65 subjects who were positive for H. pylori-specific IgG in serum, 38 (58.5%) were classified as H. pylori-specific IgA low titre in gastric juice and 27 (41.5%) had high titres. In the IgG-positive, IgA-low group, the rate of peptic ulcers (especially duodenal ulcers) in endoscopic findings was higher (P < 0.05); the score of activity and the density of H. pylori were higher (P < 0.001 and P < 0.05, respectively); the score of metaplasia was lower (P < 0.05); and the level of interleukin-1 beta was lower (P < 0.05) than in the IgG-positive, IgA-high group. The positive rate of the cagA gene was 84.4% and there was no significant difference between the two groups. There were differences in endoscopic and histological findings between the IgG-positive, IgA-low and the IgG-positive, IgA-high groups. It is suggested that persons infected with H. pylori can be divided into two different states of disease according to local immune response.     

The effect of furosemide on evoked otoacoustic emissions in guinea pigs

After recording transiently evoked otoacoustic emissions (TEOAEs) to a click stimulus in guinea pigs by using the IL088 which was developed by Bray and Kemp (1987) for easy recording and analysis of TEOAE, the changes after intravenous administration of furosemide (30 mg/kg or 50 mg/kg) were examined. The wave of the TEOAE could be detected from 20 of 24 ears (83%). After the i.v. injection of furosemide (30 mg/kg), TEOAE powers (total echo power and highest peak power in FFT pictures) decreased quickly and showed minimum values after 5-10 min. Then they increased rapidly and recovered normally within 60 min after injection. However, no ears showed TEOAEs during the 5- to 10-min period following the injection of the 50-mg/kg dose of furosemide. They then recovered slowly as compared with the group treated with the lower dose of furosemide (30 mg/kg). These changes are similar to those of the endocochlear potential (EP) after furosemide injection. These data support the notion that the EP can contribute to the mechanism of TEOAE generation.     

Opioid receptors altered binding nature in guinea-pig brain following the development of morphine dependence

Morphine is well known to produce tolerance and dependence. The mechanisms for these phenomena are not clearly understood and there are a number of conflicting reports that chronic morphine administration decreases, increases, or leaves unchanged the number of opioid binding sites. We examined the potency of MScontin (oral controlled-release preparation of morphine) to induce morphine dependence and also determined the change of mu, delta and kappa opioid receptor types in brain homogenates obtained from morphine-dependent guinea-pigs. 1. Guinea-pigs were implanted subcutaneously with MScontin (300 mg.kg-1) and naloxone was employed to precipitate jumping behavior of withdrawal symptoms at various times. The highest degree of physical dependence was observed on the 2nd day after implantation. Therefore, this period was chosen to investigate opioid receptor binding assay. 2. Two days after implantation, the binding of 3H-DAGO (mu agonist), 3H-DPDPE (delta agonist) and 3H-U69593 (kappa agonist) to brain membranes prepared from morphine dependent and control guinea-pigs was determined. Scatchard plot of the saturation binding data revealed an increase in Bmax values (maximum specific binding) and no change in the Kd values (equilibrium dissociation constants) of 3H-opioid ligand bindings obtained from morphine-dependent animals as compared to controls. These results indicate that brain mu, delta and kappa opioid receptors are up-regulated in morphine dependent guinea-pigs.     

Catalytic activity and solid acidity of vanadium oxide thin layer loaded on TiO2, ZrO2, and SnO2

Vanadium oxide spread highly on TiO₂ (anatase, A) and SnO₂, and rather densely on TiO₂ (rutile, R) and ZrO₂ to make the monolayer in less than 4–5 V nm⁻². Profile of acid site of the monolayer was measured by temperature programmed desorption of ammonia, and its relation with the surface oxidation state was studied. The acid site density was high on the V₂O₅/TiO₂ (A) independent of the degree of oxidation. On the other hand, that of V₂O₅/TiO₂ (R) and V₂O₅/ZrO₂ depended on the oxidation state, and the high value of the concentration was observed on the oxidized one. The strength of acid site generated on the V₂O₅ monolayer on TiO₂ was as high as on the HZSM-5 zeolite. Turnover frequency (TOF) of propane conversion, and product selectivity were measured in propane oxidation. Among tested oxides, the V₂O₅/TiO₂ (A) showed the high TOF and selectivity to form propylene, while those loaded on TiO₂ (R) and ZrO₂ the small TOF and poor selectivity. Therefore, the reaction profile of activity and selectivity could be related with the extent of spreading and solid acidity. An idea of limit of the acid site density ca. 1.5 nm⁻² on the monolayer was elucidated.     

Decomposition of chlorofluorocarbons on TiO2ZrO2

The decomposition of chlorofluorocarbons (CFCs) in the presence of water was examined over a variety of solid acid catalysts. The TiO₂ZrO₂ catalyst was found to have the highest activity and longest life among the catalysts examined. The activity of the TiO₂ZrO₂ catalysts depended upon the content of TiO₂. At the contents of TiO₂ from 58 to 90 mole%, the TiO₂ZrO₂ catalysts exhibited high activity, and these catalysts were proven to contain TiZrO₄ crystal. From the study of the XRD peak intensity of the TiZrO₄ crystal, it was highest on the TZ-58 which contained 58 mole% of TiO₂, and decreased with increasing the content of TiO₂. Furthermore, the conversion of CFC113 measured at 673 K was highest at TZ-58, and decreased gradually with increasing TiO₂ content. Therefore, the TiZrO₄ crystal influences the activity of decomposition of CFC113. However, the TiO₂ZrO₂ catalyst was gradually deactivated during the reaction due to the elimination of titanium atoms. A good relationship was found between the activity on TiO₂ZrO₂ catalyst and bond energy of CCl in the compounds of chlorofluorocarbons and hydrochlorocarbons, suggesting that the rate controlling step was the cleavage of CCl bond.     

High-speed melt spinning of bicomponent fibers: Mechanism of fiber structure development in poly(ethylene terephthalate)/polypropylene system

High-speed bicomponent spinning of poly(ethylene terephthalate)(PET)(core) and poly-propylene (PP) (sheath) was carried out and the structure development in the individual components, PET and PP, was investigated. The orientation and crystallinity development in the PET component was enhanced as compared to that of the single-component spinning while the PP component remained in a low orientation state and had a pseudohexagonal crystal structure even at high take-up speeds. To clarify the mutual interaction between the two components in bicomponent spinning, a semiquantitative numerical simulation was performed. The simulation results obtained using the Newtonian fluid model showed that the solidification stress in the PET component was enhanced while that of the PP component was decreased in comparison with the corresponding single-component spinning. This is due to the difference in the temperature dependence of their elongational viscosity. Simulation with an upper-convected Maxwell model as the constitutive equation suggested that significant stress relaxation of the PP component can occur in the spinline if the PET component solidifies earlier than does PP. Based on the structural characterization results, and the simulation results, it was concluded that the difference in the activation energy of the elongational viscosity and solidification temperature between the two polymers are the main factors influencing the mutual interaction in the bicomponent spinning process. © 1996 John Wiley & Sons, Inc.