Fabrication of Transparent Lead Lanthanum Zirconate Titanate Ceramics from Fine Powders by Two-Stage Sintering

Transparent lead lanthanum zirconate titanate (PLZT) ceramics were fabricated from fine powders using an inexpensive two-stage sintering technique. The powders were prepared by hydrolysis from low-cost inorganic precursors. In the two-stage sintering method, uniaxially pressed green pellets were densified to nearly theoretical values in an oxygen gas atmosphere during the first-stage sintering, at 1000°C for 1 h, and then residual, free lead oxide in the pellets was removed by second-stage sintering at 1100°C for 12 h. Transparent ceramic with an average grain size of 1.6 μm and a porosity of 1.3% was obtained. The transparency and dielectric characteristics of the present samples were compared with those of hot-pressed samples: The study of the polarization–field hysteresis loops of the present samples yielded a remanent polarization of 6.8 μC/m² and a coercive field of 1.6 kV/cm. The low coercive field of PLZT ceramics could potentially reduce the driving voltage of electrooptic devices in many applications.     

Effects of Samarium Oxide Addition on the Phase Composition, Microstructure, and Electrical Resistivity of Aluminum Nitride Ceramics

The phase composition, microstructure, and electrical resistivity of hot-pressed AlN ceramics with 0–4.8 wt% Sm₂O₃ additive were investigated. The phase composition was approximately consistent with that estimated from the Sm₂O₃–Al₂O₃ phase diagram using the amount of added Sm₂O₃ and oxygen content of the AlN raw material. When sintered at more than 1800°C, the AlN ceramics with 1.0–2.9 wt% Sm₂O₃ additive contained an Sm-β-alumina phase wetting the grain boundaries, and their electrical resistivity considerably decreased to 10¹⁰–10¹²Ω·cm. This resistivity decrease was caused by the continuity of the Sm-β-alumina phase with a resistivity lower than that of bulk AlN.     

Contribution of primary radical termination to radical polymerization of diethyl fumarate estimated from absolute rate constants

Summary Diethyl fumarate was radically polymerized under UV irradiation and concentration of the propagating radical was determined to be of the order of 10^-5 mol/L by scavenge with a stable free radical. The absolute rate constant for propagation (k_p) was evaluated from the overall rate of polymerization at 30°C: K_p =(2.9 ± 0.3) × 10^-2 L/mol · s. The rate constant for mutual termination of the polymer radical (k_t) was calculated from the decreasing rate of the radical concentration in the dark: k_t=8.0 L/mol·s. The k_t value determined is one twentieth of that evaluated previously by a rotating sector method. This discrepancy is accounted for by contribution of much faster primary radical termination.     

Application and development of synthetic polymer membranes. VI. Pervaporation of aqueous ethanol solution through quaternized poly[3-(N′,N′-dimethyl) aminopropylacrylamide-co-acrylonitrile] membranes

Membranes obtained from polymers, quaternized poly[3-(N′,N′-dimethyl) aminopropylacrylamide-co-acrylonitrile]s, showed selective separation of water from aqueous ethanol solution by pervaporation. The separation factor toward water reached over 15,000. Membrane performance showed a good correlation to membrane polarity. Differential scanning calorimetric melting endotherms of the water-swollen membranes were studied to clarify the state of water in the membranes. The results suggested that there are two states of water in the membrane: bound and free. The higher the fraction of bound water in the membrane, clearly, the more preferentially was water permeated.     

A wind-tunnel study on exhaust gas dispersion from road vehicles—Part I: Velocity and concentration fields behind single vehicles

By a reduced-scale model in a wind tunnel, we investigate the dispersion behavior of exhaust gas from automobiles. Two types of vehicles are considered, a passenger car and a small-size truck. Tracer gas experiments show that the exhaust gas dispersion is enhanced significantly by the vehicle wake compared to the case when the vehicle body is absent. The passenger car and the truck promote dispersion in the horizontal and the vertical direction, respectively. The wake field is analyzed by particle image velocimetry (PIV), and the distribution of the mean and the fluctuation fields is found to conform to the concentration field of the exhaust gas. The buoyancy of the exhaust gas has minor effect except on the vertical spread behind the truck whose wake flow amplifies the vertical displacement generated near the pipe exit.     

Perceived group devaluation, depression, and HIV-risk behavior among Asian gay men.

[Correction Notice: An erratum for this article was reported in Vol 27(3) of Health Psychology (see record 2008-08834-013). In the aforementioned article, the second sentence of the Results portion of the abstract should read: Among participants most attracted to Whites, group devaluation was associated with higher levels of nonprimary partner UAI; but was associated with lower levels of nonprimary partner UAI among those most attracted to non-Whites.] Objective: This study examined depressive mood and HIV-risk behavior in relation to perceived group devaluation and group identity. Design: Cross-sectional survey of 192 Asian gay men. Main Outcome Measures: Depressive mood assessed using the Centers for Epidemiological Studies Depression Scale (CES-D) and self-reported receptive or insertive unprotected anal intercourse (UAI) in the past 3 months. Results: Group devaluation was positively associated with depressive mood. Among participants most attracted to Whites, group devaluation was associated with higher levels of nonprimary partner UAI, among those most attracted to non-Whites. Among participants reporting higher levels of group devaluation, those with more positive personal evaluations of the Asian gay community had lower levels of total UAI compared to those with more negative personal evaluations of the Asian gay community. Conclusions: Results suggest that group devaluation is associated with higher levels of depressive mood among Asian gay men. Asian gay men most attracted to non-Whites or hold more positive evaluations of their group may be buffered from the influence of high perceived group devaluation on UAI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Perceived group devaluation, depression, and HIV-risk behavior among Asian gay men": Correction to Chae and Yoshikawa (2008).

Reports an error in "Perceived group devaluation, depression, and HIV-risk behavior among Asian gay men" by David H. Chae and Hirokazu Yoshikawa (Health Psychology, 2008[Mar], Vol 27[2], 140-148). In the aforementioned article, the second sentence of the Results portion of the abstract should read: Among participants most attracted to Whites, group devaluation was associated with higher levels of nonprimary partner UAI; but was associated with lower levels of nonprimary partner UAI among those most attracted to non-Whites. (The following abstract of the original article appeared in record 2008-03424-002.) Objective: This study examined depressive mood and HIV-risk behavior in relation to perceived group devaluation and group identity. Design: Cross-sectional survey of 192 Asian gay men. Main Outcome Measures: Depressive mood assessed using the Centers for Epidemiological Studies Depression Scale (CES-D) and self-reported receptive or insertive unprotected anal intercourse (UAI) in the past 3 months. Results: Group devaluation was positively associated with depressive mood. Among participants most attracted to Whites, group devaluation was associated with higher levels of nonprimary partner UAI, among those most attracted to non-Whites. Among participants reporting higher levels of group devaluation, those with more positive personal evaluations of the Asian gay community had lower levels of total UAI compared to those with more negative personal evaluations of the Asian gay community. Conclusions: Results suggest that group devaluation is associated with higher levels of depressive mood among Asian gay men. Asian gay men most attracted to non-Whites or hold more positive evaluations of their group may be buffered from the influence of high perceived group devaluation on UAI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A [meso-tetrakis(4-sulfonatophenyl)porphyrinato]zinc(ii) complex as an oral therapeutic for the treatment of type 2 diabetic KKA(y) mice

We prepared and characterized [meso-tetrakis(4-sulfonatophenyl)porphyrinato]zinc(II) ([Zn(tpps)]), and investigated its in vitro insulin-mimetic activity and in vivo hypoglycemic effect in type 2 diabetic KKA(y) mice. The results were compared with those of previously proposed insulin-mimetic zinc(II) complexes and zinc sulfate (ZnSO(4)). The in vitro insulin-mimetic activity of [Zn(tpps)] was considerably better than that of bis(allixinato)zinc(II) ([Zn(alx)(2)]), bis(maltolato)zinc(II) ([Zn(mal)(2)]), bis(2-aminomethylpyridinato)zinc(II) ([Zn(2-ampy)(2)](2+)), and ZnSO(4). In particular, the order of in vitro insulin-mimetic activity of the complexes was determined to be: [Zn(tpps)]>[Zn(alx)(2)]>[Zn(mal)(2)]>[Zn(2-ampy)](2+)>ZnSO(4). [Zn(tpps)] normalized the hyperglycemia of KKA(y) mice within 21 days when administered orally at doses of 10-20 mg (0.15-0.31 mmol) Zn per kg body mass for 28 days. In addition, metabolic syndromes such as insulin resistance, the degree of renal disturbance, and the degree of liver disturbance were significantly improved in [Zn(tpps)]-treated KKA(y) mice relative to those administered with saline and ZnSO(4). The improvement in diabetes was validated by the results of oral glucose-tolerance tests and the decrease in the HbA(1c) level observed. In contrast, ZnSO(4) and the ligand H(2)tpps did not lower the elevated blood glucose level under the same experimental conditions. Based on these observations, [Zn(tpps)] is proposed to be the first orally active zinc(II)-porphyrin complex for the efficacious treatment of not only type 2 diabetes but also metabolic syndromes in animals.     

Purification and some properties of beta-fructofuranosidase I formed by Aureobasidium pullulans DSM 2404

beta-Fructofuranosidase I (FFase I) formed by Aureobasidium pullulans DSM 2404 was purified. The enzyme had a molecular weight of about 430 kDa, was not affected by various metal ions and showed high transfructosylating activity. The yield of fructooligosaccharides production using purified FFase I was 62%.