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91.
We investigated the water present in a series of radiation‐grafted fluoropolymers with similar poly(styrene sulfonic acid) (PSSA) contents with the aim of determining the influence of the initial fluoropolymer. Radiation‐grafted membranes were compared with Nafion 117 and 105. Sorption curves and differential scanning calorimetry thermograms showed that all the membranes contained the same number of water molecules tightly bound to the sulfonic acid groups; this water did not freeze. In radiation‐grafted membranes, the content of freezing water absorbed from the liquid‐phase water varied according to the swelling abilities of the membrane, which were dependent on the initial fluoropolymer. Larger pores accompanied high water uptakes and high conductivity. The amount of water absorbed from the vapor phase was similar for all radiation‐grafted membranes with similar PSSA contents, irrespective of matrix material. Nafion membranes had higher conductivities at intermediate hydration levels, and the relaxation times measured by NMR were longer than for the radiation‐grafted materials. This suggests that the channels for water and proton conduction are different in the two types of materials. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 33–42, 2002  相似文献   
92.
As a contribution to the wider use of biodegradable materials, this article reports the synthesis and testing of cationic polyelectrolyte cellulose derivatives for use as flocculation chemicals. Cellulose macroinitiator is synthesized in DMAc/LiCl solvent system by direct acylation of cellulose with 2‐bromoisobutyryl bromide. Cellulose‐graft‐poly(N,N‐dimethyl aminoethyl methacrylate) (cellulose‐g‐PDMAEMA) copolymers are prepared by copper‐mediated radical polymerization in homogeneous medium. Formation of the macroinitiator and graft copolymers is confirmed by ATR‐FTIR and 1H NMR. Quaternization of the graft chains to poly(methacryloxyethyl trimethylammonium chloride) (PMOTAC) produces cellulose‐g‐PMOTAC, which performs similarly to a commercial product in flocculation of pulp and kaolin. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40448.  相似文献   
93.
The RH devices used for ITER divertor maintenance are movers or manipulators composed of electro-hydraulic and electrical actuators. Such devices are CMM, CTM and WHMAN to assist CMM and CTM. These devices execute complex and safety-critical operations while supporting ITER reactor elements weighting several tons. Despite the differences in the load capacity and functionality, the control system of these devices can be categorized as position servo control or force servo control. In this paper we propose the use of unified software development approach currently developed and demonstrated at the DTP2. This new approach takes into account the ITER RH requirements for all maintenance devices, not only the water-hydraulic maintenance devices. The need for extensive software verification and validation utilizing international standards for safety-critical systems is addressed. This applies both to control software architecture and user interface design. In principle, we propose that all ITER maintenance devices are developed and tested with the common software architecture and user interface. This makes it possible to reuse generic software modules that are well documented and tested, resulting decreased verification and validation period and development cost. Utilising this approach also improves reliability and safety of the maintenance operations.  相似文献   
94.
The effects of cooking, baking, fermentation and drying on the extractability of β-glucan were studied. The β-glucan was isolated from porridge, bread and fermentate both fresh and dry. Analyses were performed using three hydrolysis methods: acid hydrolysis (AH) with H2SO4, lichenase hydrolysis (LH) and the modified AOAC 995.15 method (MH). As shown by the DP3:DP4 ratio, processing did not affect the structure of soluble β-glucan. Cooking increased the amount of soluble β-glucan but baking decreased it. Thus, cooking appears to be the most favourable process when health effects are concerned.  相似文献   
95.
以森林为基础的产业是一个巨大的产业并且越来越具有挑战性.需要做的是提高现有产品和服务的附加值以及开发新型的以林业为基础的产品.要达到此目的,就需要像生物技术这样的先进制造技术,并且还需要利用已有的科学发展成果.先进的以林业为基础的产品,以及高附加值产品,取决于新的、改进的制造体系和工艺.如今已经用生物技术工具,尤其是酶,来改善传统的制浆造纸工艺,提高产品质量.将来,特殊和专用的酶将为创造新附加值产品开辟新的途径.  相似文献   
96.
Gonadal and stress hormones modulate neuroplasticity and behaviour. This review focuses on our findings over the past decade on the effects of estrogens and androgens on hippocampal neurogenesis, hippocampus-dependent learning and memory and the effects of reproductive experience in the rodent. Evidence suggests that acute estradiol initially enhances and subsequently suppresses cell proliferation in the dentate gyrus of adult female rodents. Repeated exposure to estradiol modulates hippocampal neurogenesis and cell death in adult female, but not male, rodents while, testosterone and dihydrotestosterone upregulate hippocampal neurogenesis in adult male rodents. Estradiol dose-dependently affects different brain regions involved in working memory (prefrontal cortex, hippocampus), reference memory (hippocampus) and conditioned place preference (amygdala). Pregnancy and motherhood differentially regulate adult hippocampal neurogenesis and spatial working memory in the dam after weaning. These studies and others demonstrate that the female brain responds to steroid hormones differently than the male brain. It is of the upmost importance to investigate the effects on neuroplasticity and behaviour in both the male and the female, particularly when modelling diseases that exhibit sex differences in incidence, etiology or treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
97.
Model for practical prediction of creep and shrinkage of normal strength concrete, developed previously, is extended to high strength concrete. It is found that only a minor adjustment for the concrete strength effect is needed in the formulas for drying creep. The formulas for basic creep and shrinkage need no adjustment. The prediction model is compared with test data for creep and shrinkage obtained recently by Ngab, Nilson and Slate, and by Collepardi, Corradi and Valente, and a satisfactory agreement is demonstrated. The coefficient of variation of the deviations from test data is not larger than that for the normal cient of variation of the deviations from test data is not larger than that for the normal strength range. However, the existing data are rather limited and further testing is desirable.  相似文献   
98.
The exponential dilution method has been tested as a rapid means for estimation of the solubility coefficient of oxygen in liquids. The relative standard deviation of the method was 5.7%. The method is not influenced by the presence of peroxides, which interfere with chemical oxygen determinations by ferrous-ferric ion titration. Values ranging from 0.07 to 0.17 were obtained for the coefficient of solubility of oxygen in raw and refined sunflower and soybean oils of different state of oxidation at room temperature.  相似文献   
99.
100.
[Correction Notice: An erratum for this article was reported in Vol 16(2) of Journal of Occupational Health Psychology (see record 2011-06502-001). The order of authorship was listed incorrectly. The correct order is listed in the correction.] Evidence of the association between job strain, that is, a combination of high psychological demands and low job control, and markers of atherosclerosis is mixed, but few studies with repeat measures are available. The purpose of this study was to examine cross-sectional and longitudinal associations between job strain and atherosclerosis. The participants were 335 men and 374 women from the prospective Cardiovascular Risk in Young Finns study (mean age 38.5 years). Two sequential measurements of job strain and carotid intima-media thickness (IMT) were analyzed. No cross-sectional or longitudinal association between job strain and IMT was observed in women. In men, a cross-sectional association was found in 2001, but not in 2007. No dose-response effect was visible, nor a simple association between progression of job strain and progression of IMT. Instead, a more complex pattern of correlation was found in men with large decreases in job strain being associated with slower progression of IMT and combined decreases in job control and demands (a change toward passive jobs) being associated with greater IMT progression. These data suggest that temporal changes in job demands and control are associated with IMT in men via multiple mechanisms. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
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