Effect of primary structure on permselectivity of ultrathin semipermeable polybenzimidazole membrane

A series of polybenzimidazoles (PBIs) with different main chains and sulfonated PBI were successfully synthesized from the corresponding dicarboxylic acids and 3,3'‐diaminobenzidine for the formation of ultrathin, single‐component, and semipermeable membranes. Furthermore, the covalently crosslinked PBI membrane was prepared by the reaction of sulfonated PBI with divinyl sulfone. Their water transport properties were evaluated under a reverse osmosis mode and compared with the primary structure based on the water permeability (A) and salt permeability (B) values normalized by the membrane thickness. It was found that the A and B values of the PBIs were improved with increasing the weight ratio of the imidazole rings per repeating unit, the introduction of sulfonate group as the hydrophilic group to the PBI was an effective way to enhance the A value, and the crosslinked structure enhanced the salt rejection rate (R) value while maintaining the water flux. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41531.     

1,8-Cineole Ameliorates Steatosis of Pten Liver Specific KO Mice via Akt Inactivation

Hepatocyte-specific Phosphatase and tensin homolog (Pten)-knockout (KO) mice exhibit hepatic lesions analogous to non-alcoholic steatohepatitis (NASH). 1,8-cineole is a monoterpene oxide and it has several biological effects including hepatoprotective effects. In this study we revealed that 1,8-cineole ameliorates NASH of Pten KO mice. Pten KO mice were assigned to a control group without any medication or to a 1,8-cineole group injected with 50 mg/kg i.p. twice per week for eight weeks. At eight weeks, livers from each group were processed to measure triglyceride (TG) content, gene expression analysis, western blot analysis, and histological examination including Oil red O staining. 1,8-cineole ameliorated hepatic steatosis in Pten KO mice, revealed by TG content and Oil red O staining. Moreover, 1,8-cineole downregulated collagen 1a1 expression and improved liver fibrosis. Thus, 1,8-cineole has potential as a candidate to treat NASH by inactivating the Akt/PI3-kinase pathway.     

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大学是人类最纯净的精神家园,它们除了有一个象牙塔的统一标识外,每所大学还有各自所代表的建筑景观,被人们津津乐道,就像剑桥的国王礼拜堂,麻省理工的无尽长廊,北大一塔湖图的博雅塔,清华的二校门??那些耳熟能详的建筑之所以能被推崇为标志,是因为它们是历史     

Beef texture characterization using internationally established texture vocabularies in ISO5492:1992: Differences among four different end-point temperatures in three muscles of Holstein steers

‘Tenderness’ has been an important sensory characteristic for beef, although ‘tenderness’ has not been commonly defined. On the other hand, ISO5492:1992 provides internationally established vocabularies for sensory analysis with simple definition. The aim of this study was texture characterization for three beef muscles cooked to four end-point temperatures using ISO5492:1992 texture terms in Japanese to develop objective sensory evaluation terms for beef texture other than ‘tenderness.’ Longissimus, semitendinosus, and psoas major muscles harvested from three Holstein steers were cooked to 45, 60, 72, and 92 °C end-point temperatures and evaluated by a trained sensory panel. Correspondence analysis indicated that the ‘chewiness’ and ‘hardness’ defined in ISO5492 were distinguished in each muscle. Changes in the ‘chewiness’ and ‘hardness’ qualities during cooking were different from each other. These findings suggest that both ‘chewiness’ and ‘hardness’ as defined in ISO5492:1992 should be evaluated simultaneously to determine the sensory texture of beef.     

Effects of buckwheat sprouts on plasma and hepatic parameters in type 2 diabetic db/db mice

We examined the effects of buckwheat sprouts (BS) (Fagopyrum esculentum Moench) on lipid and carbohydrate metabolism and on in vivo oxidative stress in type 2 diabetic mice. Mice (C57BL/KsJ-lepr(db)/lepr(db), db/db) were fed a diet containing 0%, 5%, or 10% BS based on AIN-93G for 21 d. Plasma parameters, such as total cholesterol, arteriosclerotic index, thiobarbituric acid reactive substances (TBARS), and the HbA1c concentration of whole blood in the diabetic BS-fed groups were lower than those in the diabetic control (AIN-93G) group. Concentrations of hepatic parameters, such as lipids, total cholesterol, triglyceride, and TBARS levels in BS-fed groups, were lower than those in the diabetic control group. Although gene expressions of the hepatic lipid regulation enzymes such as 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoAR) and cholesterol 7α-hydroxylase (CYP7A1) in diabetic BS-fed groups were higher than in the diabetic control group, the elevation of mRNA level of CYP7A1 was greater than that of HMG-CoAR. In addition, concentration of bile acids in feces was higher in the diabetic BS-fed groups than in the diabetic control group. These results suggest that BS have various in vivo activities in relation to antidiabetic effects in type 2 diabetic mice, especially for improvement in lipid metabolism. It was deduced that excretion of bile acids in feces by feeding the BS diet would contribute to the suppression of the cholesterol concentration in the plasma and liver tissues of mice.     

Chaotic oscillations of a shallow cylindrical shell with a concentrated mass under periodic excitation

This paper presents effects of a concentrated mass on chaotic oscillations of a shallow cylindrical shell under gravity and periodic acceleration. The rectangular shell is simply supported and is elastically in-plane constrained. Assuming mode functions, the Donnell equation with inertia force is reduced to non-linear coupled differential equations by the Galerkin method. The chaotic response is calculated numerically and is examined by the maximum Lyapunov exponent. Dominant chaotic responses are generated within restricted frequency regions of sub-harmonic resonance of 1/2 order. As the concentrated mass increases, the chaotic response is shifted to the lower frequency region. The increment of the concentrated mass decreases the maximum Lyapunov exponent.     

Environmentally degradable, high-performance thermoplastics from phenolic phytomonomers

Aliphatic polyesters, such as poly(lactic acid), which degrade by hydrolysis, from naturally occurring molecules form the main components of biodegradable plastics. However, these polyesters have become substitutes for only a small percentage of the currently used plastic materials because of their poor thermal and mechanical properties. Polymers that degrade into natural molecules and have a performance closer to that of engineering plastics would be highly desirable. Although the use of a high-strength filler such as a bacterial cellulose or modified lignin greatly increases the plastic properties, it is the matrix polymer that determines the intrinsic properties of the composite. The introduction of an aromatic component into the thermoplastic polymer backbone is an efficient method to intrinsically improve the material performance. Here, we report the preparation of environmentally degradable, liquid crystalline, wholly aromatic polyesters. The polyesters were derived from polymerizable plant-derived chemicals--in other words, 'phytomonomers' that are widely present as lignin biosynthetic precursors. The mechanical performance of these materials surpasses that of current biodegradable plastics, with a mechanical strength, sigma, of 63 MPa, a Young's modulus, E, of 16 GPa, and a maximum softening temperature of 169 degrees C. On light irradiation, their mechanical properties improved further and the rate of hydrolysis accelerated.     

Analyzing the influence of changes in land use and management practices on the lag time of peak flows for tropical watersheds of Ethiopia

Changes in peak flow response time governed by rainfall and physical configurations of watersheds have been the topic of many studies, but other factors are also important. We aimed to analyze the dynamics in the lag time (T_L) of peak flow for a tropical watershed (Kecha) and its sub-watersheds (Dokmit, Zenjero Maderia, and Wotit Minch) in Ethiopia, as influenced by land-use changes from 1982 to 2017 and the implementation of soil and water conservation (SWC) practices since 2011. Layered maps of land use, soil type, and SWC practices were used to determine the curve number, and the Natural Resource Conservation Service hydrologic model was used to estimate T_L. We compared the estimated values against measured median values of T_L for 30 rainfall–runoff events. The estimated T_L of 1982, 2005, and 2017 varied from 9 to 19 min, 8 to 18 min, and 10 to 22 min, respectively, in the Dokmit, Zenjero Maderia, and Wotit Minch sub-watersheds. The smallest (8 min) and greatest (22 min) values of T_L were observed during 2005 and 2017, respectively. These results are likely attributable to the increased amount of cultivated area at the expense of bushland and forest in 2005 as compared to 1982, and the implementation of SWC practices in 2011–2017. Dokmit had the lowest T_L values of the three sub-watersheds, most likely because of its greater coverage of grazing and cultivated lands and degraded Nitic Luvisol. The variation in T_L values among the sub-watersheds was related to changes in both land use and SWC practices but also to the presence of degraded areas inherited from past human activities. Overall, such spatiotemporal flow response time analysis can provide useful information for the proper design of sustainable development strategies for particular niches in tropical regions of Ethiopia and elsewhere.     

Digestibility of Sweet Potato Raw Starches by Glucoamylase

Three crude glucoamylase preparations from Rhizopus sp., Chalara paradoxa and Aspergillus sp. K-27 were used to determine the digestibility of raw starches from eight sweet potato varieties. Granule sizes and amylose contents were also measured. The average granule sizes ranged between 10.5 and 14.2 μm. The amylose contents varied between 18.2 and 21.8%. The hydrolysis rates for the raw starches by any of the three glucoamylases were similar. However, starch of the variety Hi-starch had a slightly lower hydrolysis rate than other starches when Rhizopus sp, enzyme was used.     

GaAs solar cells grown on Si substrates for space use

GaAs single‐junction and InGaP/GaAs multi‐junction thin‐film solar cells fabricated on Si substrates have great potential for high‐efficiency, low‐cost, lightweight and large‐area space solar cells. Heteroepitaxy of GaAs thin films on Si substrates has been examined and high‐efficiency GaAs thin‐film solar cells with total‐area efficiencies of 18·3% at AM0 and 20·0% at AM 1·5 on Si substrates (GaAs‐on‐Si solar cells) have been fabricated. In addition, 1‐MeV electron irradiation damage to GaAs‐on‐Si cells has been studied. The GaAs‐on‐Si cells are found to show higher end‐of‐life efficiency than the conventional GaAs cells fabricated on GaAs substrates (GaAs‐ on‐GaAs cells) under high‐fluence 1‐MeV electron irradiation of more than 1 × 10¹⁵ cm⁻². The first space flight to make use of them has been carried out. Forty‐eight 2 × 2 cm GaAs‐on‐Si cells with an average AM0 total‐area efficiency of 16·9% have been evaluated in the Engineering Test Satellite No.6 (ETS‐VI). The GaAs‐on‐Si cells have been demonstrated to be more radiation‐resistant in space than GaAs‐on‐GaAs cells and 50, 100 and 200‐μm‐thick Si cells. These results show that the GaAs‐on‐Si single‐junction and InGaP/GaAs‐on‐Si multi‐junction cells have great potential for space applications. Copyright © 2001 John Wiley & Sons, Ltd.