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61.
A new reference material (RM), RM 8504, has been prepared for use as a diluent oil with Aroclors in transformer oil Standard Reference Materials (SRMs) 3075 to 3080 and SRM 3090 when developing and validating methods for the determination of polychlorinated biphenyls (PCBs) as Aroclors in transformer oil or similar matrices. SRMs 3075-3080 and SRM 3090 consist of individual Aroclors in the same transformer oil that was used to prepare RM 8504. A unit of RM 8504 consists of one bottle containing approximately 100 mL of transformer oil. No additional constituents have been added to the oil.  相似文献   
62.
Fluid flow in liquid molding processes and in other applications involving porous media is often characterized with a permeability tensor and modeled by d'Arcy's law. The permeability is a sensitive function of pore structure, which, in deformable materials, is influenced by compression and extension. The majority of previous permeability measurements on composite reinforcement fabrics did not account for deformations imposed on them by corners and curves in the mold. In the present study, transparent molds were designed with a single 90° bend in which the gap between plates was held constant throughout the flow path. Thus, the effects of fabric curvature on permeability were investigated independently of the effects of fabric compression in the thickness direction. A new experimental system was developed to visualize and quantify fluid flow in fabrics mounted in transparent molds. The reported measurements were conducted with fluid flowing through a (vertical) flat region of fabric, around the 90° curve, and then along a second (horizontal) flat region. Permeability was found to be reduced by the imposed curvature for a nonwoven polyester and three-dimensional woven glass fabric. We were able to quantify the effect of curvature on permeability for the former, but not for the latter because of an enduring, dominant nonlinear entrance resistance. For the glass, comparison of two flow rates indicates that the faster flow is characterized by a two stage filling process, whereas, at the slower rate, the liquid front fills all pores at the same time.  相似文献   
63.
Three methacryloyl hydroxamic acids were prepared and homopolymerized yielding polymers which readily formed complexes with Fe3+. The amount of hydroxamic acid available for complexation was found to be low (29–32% of theoretical). Copolymers of methacryloyl hydroxamic acid with methyl methacrylate were also synthesized. The low amount of free hydroxamic acid functionality in the copolymers was ascribed to transfer reactions in the radical polymerization which resulted in branching and deactivation of the hydroxamic acid functionality. In addition, methacryloyl hydroxamic acid was copolymerized with N‐isopropyl acrylamide to yield thermotropic polymers capable of complexing with metal ions. At low concentrations of hydroxamic acid functionality, the lower critical solution temperature of the copolymers remained similar to that reported for poly(N‐isopropyl acrylamide). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 751–758, 2000  相似文献   
64.
The present work suggests that self-control relies on glucose as a limited energy source. Laboratory tests of self-control (i.e., the Stroop task, thought suppression, emotion regulation, attention control) and of social behaviors (i.e., helping behavior, coping with thoughts of death, stifling prejudice during an interracial interaction) showed that (a) acts of self-control reduced blood glucose levels, (b) low levels of blood glucose after an initial self-control task predicted poor performance on a subsequent self-control task, and (c) initial acts of self-control impaired performance on subsequent self-control tasks, but consuming a glucose drink eliminated these impairments. Self-control requires a certain amount of glucose to operate unimpaired. A single act of self-control causes glucose to drop below optimal levels, thereby impairing subsequent attempts at self-control. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
65.
Patients with panic disorder with agoraphobia (n = 40) or obsessive- compulsive disorder (n = 61) participated in a 10-min problem-solving interaction with their primary relative. Relatives were categorized as hostile or nonhostile toward the patient on the basis of a measure of expressed emotion (EE). Observed interactions between patients and their hostile relatives, relative to those of dyads with a nonhostile relative, were marked by higher rates of relatives' criticism and of patients' negativity but not by higher rates of negative reciprocity. Analyses of sequences indicated that the dyads with a hostile relative had a higher rate of sequences in which the relative was first critical and the patient then negative than was the case for dyads with nonhostile relatives. Moreover, hostile relatives were more frequently critical than nonhostile relatives whether patients' preceding behavior was positive, negative, or neutral. The findings are consistent with the stress-vulnerability model of the effect of EE on mental health, in that patients living with a high EE relative appear to be exposed to higher levels of interpersonal stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
66.
A survey questionnaire was used to ascertain the views of 1932 UK drivers aged between 50 and 90 on a range of measures designed to promote safer driving among the elderly. Factor analysis of the items produced six factors, relating to statistically distinct types of measure. Differences in acceptability on the basis of age and sex were explored. Ratings of the effectiveness of each measure revealed little consensus about which measures would be most effective. Compulsory re-testing after a driving ban, a police power to require an assessment of the driving of anyone observed driving in a risky manner, and a requirement for opticians to report to the licensing authority any driver with sight problems likely to affect driving emerged as the individual measures offering the best combination of acceptability and perceived effectiveness.  相似文献   
67.
Biochemical changes in living cells are detected using a fiber probe system composed of a single chalcogenide fiber acting as both the sensor and transmission line for infrared optical signals. The signal is collected via evanescent wave absorption along the tapered sensing zone of the fiber. We spectroscopically monitored the effects of the surfactant Triton X-100, which serves as a toxic agent simulant on a transformed human lung carcinoma type II epithelial cell line (A549). We observe spectral changes between 2800-3000 cm(-1) in four absorptions bands, which are assigned to hydrocarbon vibrations of methylene and methyl groups in membrane lipids. Comparison of fiber and transmission spectra shows that the present technique allows one to locally probe the cell plasma membrane in the lipid spectral region. These optical responses are correlated with cellular metabolic activity measurements and LDH (lactate dehydrogenase) release assays that indicate a loss of cellular function and membrane integrity as would be expected in response to the membrane solubilizing Triton. The spectroscopic technique shows a significantly greater detection resolution in time and concentration.  相似文献   
68.
For brittle composite materials, a mixed experimental and structural model is developed to determine a consistent interlaminar shear fracture toughness (GIIc) in an end notched flexure (ENF) test. The ENF procedure presented here differs from the customary ENF test in that one specimen is used for multiple measurements of compliances and the corresponding critical loads and crack growths; this procedure reduces the number of specimens needed to determine GIIc. Using this test procedure, GIIc is difficult to compute from only the experimental results because the critical load is sensitive to the inhomogeneity of the material and the specimen variation; thus a model that integrates the experimental results with structural beam theory is developed. Using the experimental results, a functional relationship between the critical load and the important geometric and material properties is obtained. A structural model is developed from Castigliano′s second theorem to compute the flexural and transverse shear deflection of the delaminated beam. Experimental results are presented for three 32‐ply multidirectional graphite‐epoxy laminates: 0°32; 0°4, 90°8, 0°4; and 0°4, ±45°2, ?45°2, ldquo;0°4. The structural model is compared with the experimental compliance and deflection results, and GIIc is determined using the experimental and structural model. GIIc obtained by this experimental procedure is compared to the GIIc determined using the customary ENF test procedure.  相似文献   
69.
This study investigated prospective risk factors for increases in body dissatisfaction in adolescent girls and boys in the Eating Among Teens Project. At the time of first assessment (Time 1), participants were a cohort of early adolescent girls (N=440) and boys (N=366) and a cohort of middle adolescent girls (N=946) and boys (N=764). Participants were followed up 5 years later (Time 2). Potential prospective risk factors examined included body mass index, socioeconomic status, ethnicity, parent dieting environment, peer environment, and psychological factors. Predictors of Time 2 body dissatisfaction were Time 1 body dissatisfaction, body mass index, socioeconomic status, being African American, friend dieting and teasing, self-esteem, and depression. However, the profile of predictors differed across the samples. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
70.
Continuing urbanisation is triggering an increase in multi-titled housing internationally. This trend has given rise to a substantial research interest in the social consequences of higher density living. Fewer enquiries have been directed to examining how property title subdivisions generate social issues in multi-titled housing. This is a significant gap in the literature, as the tensions inherent in multi-title developments have significant implications for individuals, developments and entire metropolitan areas. This article employs a life cycle framework to examine the profound operational and governance challenges that are associated with the fusion of private lot ownership with common property ownership. The article calls for a more explicit recognition of these challenges by academics, policymakers, practitioners and the broader community.  相似文献   
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