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21.
Synchrotron-source X-ray computerized microtomography (CMT) was used to evaluate the adsorptive properties of aggregate soil samples. A linear relationship between measured mean mass attenuation coefficient (sigma) and mass fraction iron was generated by imaging mineral standards with known iron contents. On the basis of reported stoichiometries of the clay minerals and identifications of iron oxyhydroxides (1), we calculated the mass fraction iron and iron oxyhydroxide in the intergranular material. The mass fractions of iron were estimated to range from 0.17 to 0.22 for measurements made at 18 keV and from 0.18 to 0.21 for measurements made at 26 keV. One aggregate sample also contained regions within the intergranular material with mass fraction iron ranging from 0.29 to 0.31 and from 0.33 to 0.36 for the 18 and 26 keV measurements, respectively. The mass fraction iron oxyhydroxide ranged from 0.18 to 0.35 for the low-iron intergranular material and from 0.40 to 0.59 for the high-iron intergranular material. Using absorption edge difference imaging with CMT, we visualized cesium on the intergranular material, presumably because of adsorption and possible exchange reactions. By characterizing the mass fraction iron, the mass fraction iron oxyhydroxide, and the adsorptive capacity of these soil mineral aggregates, we provide information useful for conceptualization, development, and parametrization of transport models.  相似文献   
22.
One of the three national games of Ireland, hurling is a contact team sport (15 a side) played with a metre long ash stick and a small hard leather ball. Over a 12 month period, 413 players were treated for hurling-related injuries at Cork Regional Hospital. While hand and facial trauma predominate, the proportion between the two sites has changed substantially from previous reports with a reduction in the level of facial injuries. The wearing of a helmet, and optionally a supplementary faceguard, is seen to have contributed to this trend. Despite this welcome reduction of facial injuries, a certain resistance to the use of protective headgear is evident, particularly among older players.  相似文献   
23.
The economic relationship between China and Myanmar is regarded as a win–win cooperation. However, Chinese investments, especially in extractive and natural resource sectors, are associated with a number of unwanted environmental consequences. Moreover, the environmental impact assessment (EIA) quality of Chinese enterprises has often been criticized. EIA identifies adverse impacts to the environment through evidence-based decision making. On this basis, this paper provides an evaluation of Chinese EIA performance within the natural resources sector through a structured review of 15 environmental impact statements (EISs). This research also evaluates the EISs of the three largest and most controversial projects, the Myitsone Hydropower Dam, Lappadaung Copper Mine and Sino-Myanmar oil and gas pipelines. The findings reveal several omissions, inadequacies and deficiencies in all the projects with a significant number of EISs falling short of satisfactory quality. Through the analysis, the paper summarizes the factors affecting the EIA performance and proposes feasible recommendations to improve EIA practices in Chinese development projects in Myanmar.  相似文献   
24.
Human Ishikawa endometrial cells form domes when confluent monolayers are stimulated with fresh fetal bovine serum. Extensive structural and biochemical changes have been detected during the approximately 30 h differentiation period. The earliest detectable change involves the formation of multinucleated structures and the appearance of "granules" that stain for biotin within those structures. Nuclei become associated with each other and are ultimately enclosed within a biotin-containing membrane. Aggregated membrane-sheathed nuclei and the cells containing them begin to elevate from the dish as biotin staining becomes apparent in apical membranes. The elevated structures are called predomes and consist of one or more very large cells containing the sheathed nuclei. Apical membranes of these unusual cells extend far out into the medium in structures that resemble endometrial pinopods. A lumen under the elevated cells fills with transcytosed fluid. As differentiation proceeds, highly concentrated chromatin material that was flattened against apical and lateral membranes of the predome cells begins to disperse. Small mononuclear cells evolve from larger predome cells. Apical membranes of predome and dome cells continue to stain for biotin. Gel electrophoresis of SDS-solubilized biotin-containing membranes, followed by Western blot analysis using avidin-linked peroxidase, resulted in three stained bands with molecular weights similar to those of the mitochondrial carboxylases: propionyl carboxylase, methylmalonyl carboxylase, and pyruvate carboxylase.  相似文献   
25.
The solid and thermally instable azoinitiators V‐65 and VR‐110 were embedded within a polymer particle by using the miniemulsion process and afterwards quickly decomposed by thermal treatment below the glass temperature of the polymer. The resulting nitrogen gas overpressure inside the particles leads to a disruption of the polymer particle and a possible sudden release of encapsulated substances. It is shown, by electron microscopic measurements, that the number of burst particles correlates with the applied temperatures as well as the heating time. The surface deformation could be verified by scanning electron microscope analyses.

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26.
Reducing cost and increasing energy density are two barriers for widespread application of lithium-ion batteries in electric vehicles. Although the cost of electric vehicle batteries has been reduced by ~70% from 2008 to 2015, the current battery pack cost ($268/kWh in 2015) is still >2 times what the USABC targets ($125/kWh). Even though many advancements in cell chemistry have been realized since the lithium-ion battery was first commercialized in 1991, few major breakthroughs have occurred in the past decade. Therefore, future cost reduction will rely on cell manufacturing and broader market acceptance. This article discusses three major aspects for cost reduction: (1) quality control to minimize scrap rate in cell manufacturing; (2) novel electrode processing and engineering to reduce processing cost and increase energy density and throughputs; and (3) material development and optimization for lithium-ion batteries with high-energy density. Insights on increasing energy and power densities of lithium-ion batteries are also addressed.  相似文献   
27.
This article examines item stability when the same item appears in different contexts. The 1st section considers the assumptions in classical test theory and item response theory concerning the relationship between the item and the trait it is presumed to measure. The 2nd section presents contextualist challenges to the measurement theory assumptions about item properties and shows the instability of item characteristics across different testing contexts. The 3rd section describes methods for checking the relationship between items and traits. Classical test methods, item response methods, and structural equation methods for assessing item stability are reviewed. The instability of item characteristics across contexts should caution researchers to assess, and not assume, that items operate the same way on different test versions. Item instability also indicates the need for a more detailed understanding of the psychological processes that occur between item and answer. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
28.
Enterococci are natural residents of human and animal intestinal tracts and grow to high levels in a variety of artisanal cheeses. The aim of this study was to determine the diversity of enterococci in a farmhouse raw-milk cheese production unit. Putative enterococci were isolated from the faeces of all the cows and all the people associated with the cheesemaking, from the milk and cheese during manufacture and ripening and from the environment in three separate trials. Almost 1400 isolates were screened using a genus-specific primer. The results indicated that all the human, milk, curd and cheese isolates but only 33.7%, 6.7% and 4.4% of the bovine isolates from the three trials, respectively, were members of the genus Enterococcus. RAPD-PCR was used to type the enterococcal isolates. In general, only E. faecium was found in the bovine faeces while E. casseliflavus dominated the human faeces, milk and cheese followed by lower numbers of E. faecalis. Environmental sampling of the water in the milking parlour and rinses of the cows' teats, the bulk-milk storage tank and the milking machine corroborated these results as E. casseliflavus and E. faecalis were the only Enterococcus species found in these samples. The putative vancomycin-resistant enterococci (VRE), isolated in Trial 1, were shown to be Pediococcus spp. by genotypic and phenotypic analysis.  相似文献   
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30.
Night shift paralysis in air traffic control officers   总被引:3,自引:0,他引:3  
S Folkard  R Condon 《Ergonomics》1987,30(9):1353-1363
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