Hydration and proton conduction in Nafion/ceramic nanocomposite membranes produced by solid‐state processing of powders from mechanical attrition

A solid‐state method of Nafion/ceramic nanocomposite membrane preparation was used. Nanocomposite powders from Nafion pellets and a zirconium phosphate ceramic were formed by mechanical attrition. The powders were consolidated into membrane form by mechanical pressing. A decrease in the particle size and improved dispersion of the ceramic within the polymer phase were confirmed with scanning electron microscopy. An evaluation of membrane hydration by thermogravimetric analysis indicated that the prepared membranes had increased water uptake in comparison with a commercially available membrane. However, as the distribution of the ceramic was improved, the hydration of the sample was reduced. Low‐temperature differential scanning calorimetry indicated that the additional water contributed to an increase in the contents of both freezing and nonfreezing water in the membranes. Proton conductivity testing at various relative humidities and temperatures revealed that the prepared membranes had conductivities comparable to but somewhat lower than those of the commercial membranes. An increase in conductivity was seen with decreased particle size and improved dispersion of the ceramic. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Protein docking using continuum electrostatics and geometric fit

The computer program DOT quickly finds low-energy docked structuresfor two proteins by performing a systematic search over sixdegrees of freedom. A novel feature of DOT is its energy function,which is the sum of both a Poisson–Boltzmann electrostaticenergy and a van der Waals energy, each represented as a grid-basedcorrelation function. DOT evaluates the energy of interactionfor many orientations of the moving molecule and maintains separatelists scored by either the electrostatic energy, the van derWaals energy or the composite sum of both. The free energy isobtained by summing the Boltzmann factor over all rotationsat each grid point. Three important findings are presented.First, for a wide variety of protein–protein interactions,the composite-energy function is shown to produce larger clustersof correct answers than found by scoring with either van derWaals energy (geometric fit) or electrostatic energy alone.Second, free-energy clusters are demonstrated to be indicatorsof binding sites. Third, the contributions of electrostaticand attractive van der Waals energies to the total energy termappropriately reflect the nature of the various types of protein–proteininteractions studied.     

Effect of Lubricant on the Surface Structure of Aluminosilicate Fibers

Commercial aluminosilicate fibers of the nominal composition 45 wt% Al₂O₃, 54 wt% SiO₂ have similar bulk properties but different surface chemistries, depending on whether they were formed with (WL) or without (NL) the aid of a mineral-oil lubricant. Both fiber samples are X-ray amorphous as formed; they have similar crystallization temperatures and have activation energies for crystallization of 751 and 854 kJ/mol for samples NL and WL, respectively. Fiber surface properties differ markedly, as indicated by diffuse reflectance infrared transmission spectroscopy and X-ray photoelectron spectroscopy. These techniques show that carbon from the lubricant degradation and/or combustion is incorporated into the melt, whereupon it reacts with nonbonding oxygens in the Al-O network to form network carbonates.     

The current state of empirical support for the pharmacological treatment of selective mutism.

This article reviews the current state of evidence for the psychopharmacological treatment of children diagnosed with selective mutism within the context of its link to social anxiety disorder. An increased focus on potential medication treatment for this disorder has resulted from significant monetary and resource limitations in typical practice, parental choice in utilizing treatment from medical personnel, and children who fail to respond to psychosocial interventions. A total of 21 publications within the English literature were located. From these, data for only 57 children between the ages of 4 to 17 years have been reported, with the majority of studies utilizing single-case design or case study methodology. Yet, pharmacological data appear promising for treatment resistant cases of selective mutism. The need for additional research via efficacy/effectiveness methodologies remains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Blockade of tetrahydrobiopterin synthesis protects neurons after transient forebrain ischemia in rat: a novel role for the cofactor

The generation of nitric oxide (NO) aggravates neuronal injury. (6R)-5,6,7,8-Tetrahydro-L-biopterin (BH4) is an essential cofactor in the synthesis of NO by nitric oxide synthase (NOS). We attempted to attenuate neuron degeneration by blocking the synthesis of the cofactor BH4 using N-acetyl-3-O-methyldopamine (NAMDA). In vitro data demonstrate that NAMDA inhibited GTP cyclohydrolase I, the rate-limiting enzyme for BH4 biosynthesis, and reduced nitrite accumulation, an oxidative metabolite of NO, without directly inhibiting NOS activity. Animals exposed to transient forebrain ischemia and treated with NAMDA demonstrated marked reductions in ischemia-induced BH4 levels, NADPH-diaphorase activity, and caspase-3 gene expression in the CA1 hippocampus. Moreover, delayed neuronal injury in the CA1 hippocampal region was significantly attenuated by NAMDA. For the first time, these data demonstrate that a cofactor, BH4, plays a significant role in the generation of ischemic neuronal death, and that blockade of BH4 biosynthesis may provide novel strategies for neuroprotection.     

Expression of fibroblast growth factor family during postnatal skeletal muscle hypertrophy

The potential role of the fibroblast growth factor (FGF) family during stretch-induced postnatal skeletal muscle hypertrophy was analyzed by using an avian wing-weighting model. After 2 or 11 days of weighted stretch, anterior latissimus dorsi (ALD) muscles were, on average, 34 (P < 0.01) and 85% (P < 0.01) larger, respectively, than unweighted ALD control muscles. By using quantitative RT-PCR, FGF-1 mRNA expression was found to be significantly decreased in ALD muscles stretched for 2 or 11 days. In contrast, FGF-4 and FGF-10 mRNA expression was significantly increased 2 days after initiation of stretch. FGF-2, FGF-10, fibroblast growth factor receptor 1, and FREK mRNA expression was significantly increased at 11 days poststretch. Increases in FGF-2 and FGF-4 protein could be detected throughout the myofiber periphery after 11 days of stretch. On a cellular level, FGF-2 and FGF-4 proteins were differentially localized. This differential expression pattern and protein localization of the FGF family in response to stretch-induced hypertrophy suggest distinct roles for individual FGFs during the postnatal hypertrophy process.     

大卫的戏剧舞台Magic Life

<正>沿着位伦敦东区的Mile End路走到大卫卡特的五层楼房,那景象就像小说《绿野仙踪》中描述的那样:一切均在瞬间从黑白色调变成了缤纷多彩的画面。徜徉于这所房间之内,你会看到弯曲的廊道、大理     

Shortening for the cake baker

A discussion of shortening requirements based on the problems of commercial cake baking. The author attempts to briefly indicate what properties are sought for by the baker in his effort to produce superior results. The influence of shortening on finished products and the suitability of types of shortening to meet shop practices are reviewed. This discussion was presented at the Fall Convention of the American Oil Chemists Society, Chicago, October, 1938.     

Fast reactor decay heat removal: approach to the safety system design in Japan and Europe

In the framework of the cooperation on fast reactor between the European and Japanese electrical utilities, the design companies responsible for the demonstration fast breeder reactor (DFBR) in Japan and the European fast reactor (EFR) have performed a comparative evaluation of the safety qualified decay heat removal systems of the two reactor designs. At the level of overall safety and concept design there is an obvious similarity between the two DHR systems. In both cases heat is removed directly from the reactor vessel primary sodium by systems designed according to a similar deterministic methodology, with a probabilistic assessment performed to demonstrate achievement of the required reliability. Nevertheless, the evaluation revealed a number of differences resulting from different national practices. These include the application of diversity and redundancy philosophy, the extent of passivity taken into account, the consequences of postulated maintenance outage on the design and the decay heat curve.