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41.
A method for bromine, chlorine, and iodine determination in soybean and related products was developed by inductively coupled plasma mass spectrometry (ICP-MS) after digestion by microwave-induced combustion (MIC). Samples were pressed as pellets and combusted using pressurized oxygen (20 bar) and ammonium nitrate solution (50 μL of 6 mol L?1) as the igniter. Analytes were absorbed in alkaline solution (100 mmol L?1 NH4OH), and a reflux step of 5 min, microwave power of 1,400 W, was applied after combustion in order to improve analyte recoveries. For Cl determination by ICP-MS, a dynamic reaction cell was used with ammonia as the reaction gas. The accuracy was evaluated using certified reference materials (CRMs) and spiked samples. Using MIC, the agreement with CRM values and spike recoveries was higher than 95 % for all analytes for certified reference materials of a similar composition (National Institute of Standards and Technology (NIST), corn bran and NIST, whole milk). Limits of detection were 0.03, 1.2, and 0.002 μg g?1 for Br, Cl, and I, respectively. The residual carbon content in the digests obtained after MIC procedure was lower than 0.5 %. Blanks were always negligible and no memory effects were observed. Digestion by MIC allowed processing up to eight samples by each run in 25 min with high efficiency of digestion providing a suitable medium for further bromine, chlorine, and iodine determination by ICP-MS.  相似文献   
42.
A feasibility study on hydrogen production from wind power on the site of Ghardaia is carried out. This study is based on the estimation of the hydrogen rate produced by a 5 kW electrolyser fed by the electricity provided by a 10 kW wind turbine.Wind speed data were used to study the monthly variation of the wind power delivered and its variation according to the height of the wind turbine tower.The obtained results show that it is possible to improve the system output by increasing the height of the wind turbine tower. Indeed, it has been obtained 3200 Nm3 of hydrogen production for a 30 m wind turbine height and 4200 Nm3 at 60 m.In addition, it has been noticed that hydrogen production varies strongly with the months of the year. Thus, the production has reached a maximum of 395 Nm3 in May and a minimum of 187 Nm3 during November and October.  相似文献   
43.
The authors draw on stress and coping theory to understand patterns of individual response to workplace incivility. According to data from 3 employee samples, incivility tended to trigger mildly negative appraisals, which could theoretically differentiate incivility from other categories of antisocial work behavior. Employees experiencing frequent and varied incivility from powerful instigators generally appraised their uncivil encounters more negatively. They responded to this stressor using a multifaceted array of coping strategies, which entailed support seeking, detachment, minimization, prosocial conflict avoidance, and assertive conflict avoidance. These coping reactions depended on the target’s appraisal of the situation, the situation’s duration, and the organizational position and power of both target and instigator. Implications for organizational science and practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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The objective of this study was to quantify and assess whether push/pull tasks in the workplace are risk factors for lower back pain etiology. A case‐control study was conducted of 231 industrial workers 18–55 years old who were insured by the Mexican Social Security Institute (MSSI) in the Guadalajara Metropolitan Area of Jalisco, Mexico. Exposure was evaluated via a questionnaire. Multivariate analysis using conditional logistic regression showed risks for push/pull tasks (odds ratio = 5.7, 95% confidence interval, 1.4–23.1) adjusted for lifting, carrying, and driving work. The fraction attributable to push/pull tasks was 0.58, suggesting that the risk of developing lumbar spondyloarthrosis might be reduced by 58% with ergonomic redesign for pushing and pulling tasks at workstations. Additional research is needed to confirm this relationship and will ideally incorporate a greater number of subjects to assure detailed analyses of exposure categories and facilitate new comparisons with the results of the present study. © 2012Wiley Periodicals, Inc.  相似文献   
46.
In this paper, we aim at exploiting the power computing of a graphics processing unit (GPU) cluster for solving large sparse linear systems. We implement the parallel algorithm of the generalized minimal residual iterative method using the Compute Unified Device Architecture programming language and the MPI parallel environment. The experiments show that a GPU cluster is more efficient than a CPU cluster. In order to optimize the performances, we use a compressed storage format for the sparse vectors and the hypergraph partitioning. These solutions improve the spatial and temporal localization of the shared data between the computing nodes of the GPU cluster.  相似文献   
47.
The biaxial molecular orientation of blown films made of blends of linear low density polyethylene (LLDPE) with low density polyethylene (LDPE) was characterized by two different methods: complete pole figures obtained by wide angle X‐rays diffraction (WAXD) and polarized infrared spectroscopy (IR) using the Krishnaswamy approach. The molecular orientation of the blends amorphous phase was also evaluated by polarized IR. The crystallinity of the blown films was determined by WAXD. A good correlation between the X‐ray pole figures and the polarized IR results was obtained. At all blends compositions, it was shown that the a‐axis of the polyethylene orthorhombic cell was preferentially oriented along the machine direction, the orientation degree along this direction increasing with the increase of the LDPE amount in the blends. The b‐axis changed its preferential orientation from film thickness in the 100/0 LLDPE/LDPE film to along the transverse direction with increasing LDPE in the blends. The c‐axis changed its orientation from orthogonal to normal direction in the 100/0 LLDPE/LDPE film to along the film thickness with increasing LDPE in the blends. Polarized IR characterization showed a negligible orientation of the amorphous phase. The amount of crystallinity was dependent on blend composition decreasing with the increase of LDPE content in the blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2760–2767, 2006  相似文献   
48.
Increasingly, countries around the world are adopting policies that emphasize the importance of partnerships for disaster resilience. The overarching questions that this paper investigates are how to form and sustain (1) effective collaborative arrangements involving governments, businesses, non‐governmental organizations and communities to ensure development of disaster resilient communities, and (2) governance institutions that can effectively mobilize geographically dispersed disaster response resources with fragmented ownership. We have reviewed case studies of alternative inter‐sectoral collaborative arrangements that were formed to (1) promote the development of resilient communities and critical physical and social systems; (2) mitigate or respond to emerging crises; or (3) facilitate post‐disaster recovery and learning. We have developed grounded propositions articulating the antecedents of performance of inter‐sectoral collaborative arrangements.  相似文献   
49.
Valley polarization of multi‐valleyed materials is of significant interest for potential applications in electronic devices. The main challenge is removing the valley degeneracy in some controllable way. The unique properties of bismuth, including its anisotropic electronic structure and Dirac valley degeneracy, make this material an excellent system for valleytronics. It is demonstrated theoretically that the direction of an externally applied magnetic field in the binary‐bisectrix plane has a profound effect not only on the charge, but also on the thermal transport along the trigonal direction. The rotating field probes the electronic mass anisotropy and tunes the contribution from a particular Dirac valley in the electrical resistivity, Seebeck coefficient, and thermal conductivity at moderate temperatures and field strengths. It is further shown that the field polarization of the transport properties is accompanied by selective filtering of the carriers type providing further opportunities for thermoelectric transport control.  相似文献   
50.
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