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61.
Nature of the porosity in American coals 总被引:9,自引:0,他引:9
The nature of the porosity in a number of 40 × 70 (i.e. − 40 + 70) mesh size American coals, varying in rank from anthracite to lignite, has been studied using the following characterization techniques: gas adsorption, helium and mercury displacement, and mercury porosimetry. Surface areas calculated from carbon dioxide adsorption at 298 K are consistently higher than those calculated from nitrogen at 77 K, indicating the molecular sieve character of the coals. Total pore volumes have been measured in the diameter range 12–29 600 Å and then divided into macropores (300-29 600 Å), transitional pores (12–300 Å), and micropores (4–12 Å). Coals vary widely in their total pore volumes (porosities range between 4.1 and 23.2%). In the lower-rank coals (carbon content less than 75%), porosity is primarily due to the presence of macropores. In coals having a carbon content in the range 76–84%, about 80% of the total open pore volume is due to micro and transitional pores, whereas in the coals of higher carbon content microporosity predominates. Coals having about 35–55% of their total open pore volume in the transitional range are expected to be most suitable for use for adsorption of organic molecules from solution. Thus, they are of interest as possible materials to be used in water purification. In general, these results are considered to be of importance in understanding the extent and rate of interaction of coals with gases and liquids. 相似文献
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Parker Jeffrey G.; Low Christine M.; Walker Alisha R.; Gamm Bridget K. 《Canadian Metallurgical Quarterly》2005,41(1):235
Children's vulnerability to jealousy surrounding their best friends was explored in 2 studies. Study 1 involved 94 adolescents who reported on their friendship jealousy on a newly created measure. Results indicated that the jealousy measure had sound psychometric properties and produced individual differences that were robust over time and free from socially desirable responding. As expected, girls and adolescents with low self-worth reported the greatest friendship jealousy. Study 2 involved 399 young adolescents and extended the measurement of self-report jealousy to a broader age range. In addition, Study 2 included assessments of jealousy provided by friends and other peers. Self- and peer-reported jealousy were only modestly associated and had somewhat distinct correlates. Structural modeling revealed that young adolescents' reputation for friendship jealousy was linked to behaving aggressively and to broader peer adjustment difficulties. Both self- and peer-reported jealousy contributed to loneliness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Ford J.E. Goossen K.W. Walker J.A. Neilson D.T. Tennant D.M. Seo Yeon Park Sulhoff J.W. 《IEEE journal of selected topics in quantum electronics》2004,10(3):579-587
Dynamic gain equalization filters (DGEFs) are important for high-performance wavelength division multiplexed (WDM) communications. One of the first demonstrated DGEF used a micromechanical etalon filter array illuminated with free-space spectral demultiplexing optics. Here, we present subsequent research on etalon-based dynamic spectral filters, including vertical device structures which linearize and reduce the drive voltage from 70 to 40 V, and spatially-segmented etalons which allow channelized spectral equalization and further reduce drive voltage. We describe a prototype using a simplified cylindrical optomechanical package with a 104-nm broadband spectral response, 7.5-dB insertion loss and less than 16-V operation voltage. Finally, we show the use of a 42-nm bandwidth DGEF prototype with feedback stabilization to more than double the number of channels and operating bandwidth of a conventional Erbium-doped fiber amplifier while maintaining < 1-dB power uniformity. 相似文献
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People's conceptions of different types of moral exemplarity were examined in an attempt to augment the current emphasis on moral rationality with a fuller understanding of moral personality. In Study 1 (with 805 adults), a free-listing procedure was used to generate the attributes of 3 types of moral exemplars (just, brave, and caring). In Study 2 (with 401 undergraduates), prototypicality- and personality-rating procedures were used to generate a personality profile for each type of moral exemplar and to examine the relations among them. In Study 3 (with 240 undergraduates), a similarity-sorting procedure was used to identify the typologies implicit in people's understanding of these different types of moral exemplarity. The findings indicate that moral excellence can be exemplified in rather divergent ways and that understanding of moral functioning would be enhanced by attention to this wider range of moral virtues. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Douglas A Stow Allen Hope David Verbyla Fred Huemmrich Charles Racine Kenneth Tape Kenji Yoshikawa Brian Noyle David Douglas Gensuo Jia Donald Walker Aaron Petersen Ranga Myneni 《Remote sensing of environment》2004,89(3):281-308
The objective of this paper is to review research conducted over the past decade on the application of multi-temporal remote sensing for monitoring changes of Arctic tundra lands. Emphasis is placed on results from the National Science Foundation Land-Air-Ice Interactions (LAII) program and on optical remote sensing techniques. Case studies demonstrate that ground-level sensors on stationary or moving track platforms and wide-swath imaging sensors on polar orbiting satellites are particularly useful for capturing optical remote sensing data at sufficient frequency to study tundra vegetation dynamics and changes for the cloud prone Arctic. Less frequent imaging with high spatial resolution instruments on aircraft and lower orbiting satellites enable more detailed analyses of land cover change and calibration/validation of coarser resolution observations.The strongest signals of ecosystem change detected thus far appear to correspond to expansion of tundra shrubs and changes in the amount and extent of thaw lakes and ponds. Changes in shrub cover and extent have been documented by modern repeat imaging that matches archived historical aerial photography. NOAA Advanced Very High Resolution Radiometer (AVHRR) time series provide a 20-year record for determining changes in greenness that relates to photosynthetic activity, net primary production, and growing season length. The strong contrast between land materials and surface waters enables changes in lake and pond extent to be readily measured and monitored. 相似文献
67.
The electron backscattering factor was measured from 24 different elements at low primary beam energy (250-5,000 eV). The results were compared with Monte Carlo simulations from a variety of freely available programs and an in-house developed program. The results suggest that a thin film of oxide can modify the backscattering factor at low primary energy. In addition, a number of problems have been identified with the freely available programs. 相似文献
68.
Excessive ingestion of licorice induces a syndrome of hypokalemia and hypertension that reflects increased activation of renal mineralocorticoid receptors by cortisol. A similar syndrome of cortisol-dependent mineralocorticoid excess occurs in congenital deficiency of the enzyme 11 beta-hydroxysteroid dehydrogenase, which normally inactivates cortisol to cortisone. It has been shown that licorice inhibits 11 beta-dehydrogenase, preventing local inactivation of cortisol and allowing cortisol inappropriate access to intrinsically nonspecific renal mineralocorticoid receptors. Further studies with licorice and its derivatives have revealed a widespread role for 11 beta-dehydrogenase in regulating tissue sensitivity to cortisol. Deficient 11 beta-dehydrogenase activity provides a novel pathogenetic mechanism for hypertension, and current research suggests that several common forms of hypertension can be explained by the mechanisms that operate in licorice-induced hypertension. 相似文献
69.
Food allergy,a summary of eight cases in the UK criminal and civil courts: effective last resort for vulnerable consumers? 下载免费PDF全文
M. Hazel Gowland Michael J Walker 《Journal of the science of food and agriculture》2015,95(10):1979-1990
Food allergy has a forensic context. The authors describe eight cases in the UK courts involving fatalities, personal injury or criminal non‐compliance with food law from mainly ‘grey’ literature sources. The potentially severe consequences for people with food allergy of contraventions of labelling law have led to enforcement action up to criminal prosecution for what might otherwise be regarded as ‘trivial’ non‐compliance. The authors suggest there should be central collation of such cases. Non‐compliances should be followed up in a more rapid and robust manner. Evidence of fraud in the catering supply chain supports recent calls for zero tolerance of food fraud. Businesses must guard against gaps in allergen management, for which there are readily available sources of training and guidance, but also against fraudulent substitution in the supply chain, about which training and guidance should be developed. New allergen labelling legislation and case law appear to place responsibility on food businesses even for the forensically problematic area of allergen cross‐contamination. The courts can be an effective last resort for vulnerable consumers; however, there is evidence of knowledge and skill gaps in both the investigation and prosecution of potentially serious incidents of food allergen mismanagement and mislabelling. Thorough investigation of food allergy deaths is required with a tenacious and skilled approach, including early realisation that samples of the food and/or stomach contents from a post mortem examination should be retained and analysed. The supply chain must be rigorously examined to find out where adulteration or contamination with the fatal allergen occurred. © 2014 Society of Chemical Industry 相似文献
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