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61.
Cornish AS Ng WC Ho VC Wong HL Lam JC Lam PK Leung KM 《The Science of the total environment》2007,376(1-3):335-345
The bamboo shark Chiloscyllium plagiosum is an abundant benthic species along the shallow continental shelf of Southeast Asia. It is commonly taken by fishermen in China, India, Taiwan and Thailand for human consumption. This study measured trace metal and organochlorine concentrations in C. plagiosum collected from the southern waters of Hong Kong, China. Metals (Ag, Cd, Cr, Cu, Mn, Ni, Pb and Zn) were measured in three different tissues: dorsal muscle, spleen and liver. Polychlorinated biphenyls (PCBs) and chlorinated pesticides in the dorsal muscle were identified and quantified using gas chromatography. Metal concentrations varied among the three different tissues, with liver having higher levels of Ag and Cd, and spleen possessing higher levels of Cu and Mn. Both Ni and Pb in all tissues were below the detection limit. Tissue concentrations of Cr, Cu, Mn and Zn generally decreased with increasing body weight whilst no significant concentration-size relationship was found for other metals. In muscle tissues, total PCBs ranged from 1.056-4.771 ng/g (wet wt.) with a median of 1.801 ng/g, while total DDTs ranged from 0.602-23.55 ng/g with a median of 1.109 ng/g, in which p,p'-DDE was the predominant metabolite. Levels of total hexachlorohexanes and cyclodienes were low. The pesticide p,p'-DDT was the only compound found to be positively correlated with body weight, indicating temporal bioaccumulation of this compound. Zn concentrations in the muscle of C. plagiosum were comparatively higher than recorded in other shark species, however, concentrations of other metals and organochlorines were relatively low. C. plagiosum feeds primarily on polychaetes, shrimps and small fishes, and thus is unlikely to contain levels of contaminants of human health concern. 相似文献
62.
Valerie Dupont Martyn V. Twigg Andrew N. Rollinson Jenny M. Jones 《International Journal of Hydrogen Energy》2013
The thermodynamic effects of molar steam to carbon ratio (S:C), of pressure, and of having CaO present on the H2 yield and enthalpy balance of urea steam reforming were investigated. At a S:C of 3 the presence of CaO increased the H2 yield from 2.6 mol H2/mol urea feed at 940 K to 2.9 at 890 K, and decreased the enthalpy of bringing the system to equilibrium. A minimum enthalpy of 180.4 kJ was required to produce 1 mol of H2 at 880 K. This decreased to 94.0 kJ at 660 K with CaO-based CO2 sorption and, when including a regeneration step of the CaCO3 at 1170 K, to 173 kJ at 720 K. The presence of CaO allowed widening the range of viable operation at lower temperature and significantly inhibited carbon formation. The feasibility of producing H2 from renewable urea in a low carbon future is discussed. 相似文献
63.
Grain subdivision and recrystallization in oligocrystalline tantalum during cold swaging and subsequent annealing 总被引:1,自引:0,他引:1
Hugo R. Z. Sandim Angelo F. Padilha Valerie Randle Wolfgang Blum 《International Journal of Refractory Metals and Hard Materials》1999,17(6):431-435
A coarse-grained ingot of high-purity tantalum was deformed by swaging at room temperature to a strain of 1.28. During annealing at 900°C for 30 min two neighboring grains were observed to behave quite differently. Electron backscattering diffraction (EBSD) results show noticeable differences in terms of the misorientations developed in both grains. The grain developing larger misorientations recrystallized much more readily than the other. The result is interpreted in terms of the differences in grain subdivision into strongly misoriented regions. 相似文献
64.
William T. Riley Steven C. Carson Norman Martin Albert Behar Valerie L. Forman-Hoffman Albert Jerome 《Computers in human behavior》2005,21(6):1005-1018
This study sought to evaluate the feasibility of a researcher configurable self-monitoring program. An initial prototype of the program was developed as a Windows-based drag and drop flow chart interface for the researcher to construct the self-monitoring or diary protocol to be scheduled and displayed to the subject on a Pocket PC. The usability of the desktop researcher interface was evaluated in a small sample of medication trial researchers whose ratings of the prototype were generally positive and provided directions for improvement. The subject interface was then evaluated in an “analog” drug trial of 49 smokers using nicotine gum. These subjects were randomly assigned to either paper-based log or Pocket PC self-monitoring for 3 weeks. Pocket PC subjects were significantly more compliant than the log subjects on recording in the second (65% vs. 39%) and third (69% vs. 39%) weeks of the trial but did not differ from the log condition on total recording entries, likely due to the restrictions on retrospective recording in the Pocket PC program. This study provides support for the feasibility of a researcher configurable electronic diary system which should substantially reduce the programming barriers to electronic self-monitoring and increase the use of real-time monitoring in clinical and research venues. 相似文献
65.
The orientation invariance of visual pattern recognition in pigeons and humans was studied using a conditioned matching-to-sample procedure. A rotation effect, a lengthening of choice latencies with increasing angular disparities between sample and comparison stimuli, was replicated with humans. The choice speed and accuracy of pigeons was not affected by orientation disparities. Novel mirror-image stimuli, rotation of sample shapes, a delayed display of comparison shapes, and a mixed use of original and reflected sample shapes did not lead to a rotation effect in pigeons. With arbitrarily different odd comparison shapes, neither humans nor pigeons showed a rotation effect. Final experiments supported the possibility that the complete absence of a rotation effect in pigeons is because they are relatively better than humans at discriminating mirror-image shapes compared with arbitrary shapes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
66.
Robertson Ian H.; Ridgeway Valerie; Greenfield Eve; Parr Alice 《Canadian Metallurgical Quarterly》1997,11(2):290
The functional recovery of 47 right-brain-damaged stroke patients was studied over a 2-year period. The researchers hypothesized that sustained attention capacity should predict the degree of motor and functional recovery over this period because of a proposed privileged role of sustained attention in learning-based recovery of function. As predicted, significant correlations were found between sustained attention capacity at 2 months and functional status (including the Barthel Index) at 2 years. This relationship was shown to exist independently of 2-month functional status. Furthermore, compared with a left-brain-damaged group of cerebrovascular accident (CVA) patients, the right-brain CVA group did not recover functional ability as well over the 2-year period. This increasing difference in functional status over a 2-year period was mirrored by an emerging difference in sustained attention capacity, in favor of the left-brain CVA group. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
67.
Event-based prospective memory requires responding to cues in the environment that are associated with a previously established intention. Some researchers believe that intentions reside in memory with an above baseline level of activation, a phenomenon called the intention superiority effect. The authors of this study predicted that intention superiority would be masked by additional cognitive processes associated with successful event-based prospective memory. These additional processes include noticing the cue, retrieving the intention, and coordinating intention execution with the ongoing activity, In 3 experiments, intention superiority was demonstrated by faster latencies to the ongoing activity on failed prospective trials and the existence of the additional processes was demonstrated by slower latencies on successful trials. This study demonstrates the importance of investigating the microstructure of the cognitive components involved with processing and responding to an event-based prospective memory cue. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
68.
Yung-Sheng Huang Dave E. Mills Ron P. Ward David F. Horrobin Valerie A. Simmons 《Lipids》1989,24(7):565-571
Weanling male spontaneously hypertensive (SHR) and normotensive (WKY) rats were maintained on a fat-free semisynthetic diet
and killed at various intervals. The effects of fat-depletion on the appearance of essential fatty acid (EFA) deficiency symptoms,
the progressive changes of major fatty acids in plasma, liver, heart, and kidney phospholipids (PL), and in skin total lipids
were compared between these two strains. After five weeks on the diet, the slower growth and the appearance of EFA deficiency
symptoms became evident in SHR. In general, fat-depletion reduced the levels of n−6 fatty acids, whereas it increased those
of 20∶3n−9. However, the fat-depletion induced reduction of 18∶2n−6 in heart PL and 20∶4n−6 in kidney, while the elevation
of 20∶3n−9 in plasma, heart, and kidney PL were greater in WKY than in SHR. As a result, the elevation of biochemical EFA
deficiency index—20∶3n−9/20∶4n−6 ratio—was greater in WKY than in SHR. In comparison with WKY, the concentrations of liver
triacylglycerols and the weights of adipose tissues in SHR were reduced to a greater extent, indicating an active catabolism
of triacylglycerols in SHR. This study suggests that the earlier appearance of morphological symptoms of EFA deficiency in
SHR was not associated with the reducing n−6 EFA levels or with an elevation of triene/tetraene ratio, but possibly to a reduced
supply of n−6 EFA for skin prostaglandin synthesis. 相似文献
69.
Microbial hazards related to rice sprouting 总被引:3,自引:0,他引:3
Valerie Piernas & Joseph P. Guiraud 《International Journal of Food Science & Technology》1997,32(1):33-39
The microbiology of rice seeds selected for commercial production of sprouts was studied. Bacteria were numerous but generally nonpathogenic: almost all were gram-negative rods, predominantly pseudomonads. There were also several enterobacteria, in particular Enterobacter and Klebsiella species. Escherichia coli was present in very few samples and its serotype was not enteropathogenic. Moulds were infrequent. Storage of seeds under laboratory conditions did not greatly modify the composition of the microflora but counts decreased with time. When grains were stored in a cold room, the microflora remained almost unchanged quantitatively and qualitatively. After 2 days of germination, mesophilic aerobic plate counts increased by about 2 log cycles; thermotolerant coliforms and faecal enterococci increased by up to 6 log cycles. No foodborne pathogens were detected on sprouts. Moreover, both dry seeds and sprouts were negative for aflatoxins. Experiments with artificially inoculated seeds showed that Bacillus cereus and Listeria sp. could develop without any antagonistic effect from the background flora of germinating rice. 相似文献
70.
Valerie M. Muller Rita V. Burke Helen Arbogast Perla C. Ruiz Nellie M. Nunez Katherine R. San Mateo Francesca Cazzulino Jeffrey S. Upperman 《Accident; analysis and prevention》2014