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121.
Parveen S Taabodi M Schwarz JG Oscar TP Harter-Dennis J White DG 《Journal of food protection》2007,70(11):2466-2472
This study was conducted to determine the prevalence and antimicrobial resistance of Salmonella isolates recovered from processed poultry. Four hundred eighty pre- and postchill whole broiler chicken carcasses were collected from a poultry processing plant between July 2004 and June 2005. Water samples also were collected at the entrance and exit of the chiller. After preenrichment, carcass and water samples were analyzed for the presence of Salmonella using the automated BAX system followed by traditional culture methods. The proportions of pre- and postchill carcasses that were positive for Salmonella were 88.4 and 84.1%, respectively. Ninety-two percent of water samples collected at the entrance of the chiller were positive for Salmonella, but all exit samples were negative. There was no significant difference in the prevalence of Salmonella between pre- and postchill carcasses (P > 0.05). Salmonella isolates recovered were serotyped and tested for susceptibility to antimicrobials. Thirteen serotypes were identified; the most common were Salmonella Kentucky (59.5%) and Salmonella Typhimurium (17.8%). Three hundred thirty-nine (79.8%) of the isolates were resistant to at least one antimicrobial, and 53.4% were resistant to three or more antimicrobials. Resistance was most often observed to tetracycline (73.4% of isolates), ampicillin (52.9%), amoxicillin-clavulanic acid (52%), ceftiofur (51.7%), streptomycin (35.2%), and sulfisoxazole (21.8%). These results indicate the high prevalence of Salmonella contamination in whole broiler carcasses, and a large number of these Salmonella isolates were resistant to commonly used antimicrobials. 相似文献
122.
In this paper, a wind farm controller is developed that distributes power references among wind turbines while it reduces their structural loads. The proposed controller is based on a spatially discrete model of the farm, which delivers an approximation of wind speed in the vicinity of each wind turbine. The control algorithm determines the reference signals for each individual wind turbine controller in two scenarios based on low and high wind speed. In low wind speed, the reference signals for rotor speed are adjusted, taking the trade-off between power maximization and load minimization into account. In high wind speed, the power and pitch reference signals are determined while structural loads are minimized. To the best of authors’ knowledge, the proposed dynamical model is a suitable framework for control, since it provides a dynamic structure for behavior of the flow in wind farms. Moreover, the controller has been proven exceptionally useful in solving the problem of both power and load optimization on the basis of this model. 相似文献
123.
This paper compares the hot corrosion performance of yttria stabilized zirconia (YSZ), Gd2Zr2O7, and YSZ + Gd2Zr2O7 composite coatings in the presence of molten mixture of Na2SO4 + V2O5 at 1050 °C. These YSZ and rare earth zirconate coatings were prepared by atmospheric plasma spray (APS). Chemical interaction is found to be the major corrosive mechanism for the deterioration of these coatings. Characterizations using X-ray diffraction (XRD) and scanning electron microscope (SEM) indicate that in the case of YSZ, the reaction between NaVO3 and Y2O3 produces YVO4 and leads to the transformation of tetragonal ZrO2 to monoclinic ZrO2. For the Gd2Zr2O7 + YSZ composite coating, by the formation of GdVO4, the amount of YVO4 formed on the YSZ + Gd2Zr2O7 composite coating is significantly reduced. Molten salt also reacts with Gd2Zr2O7 to form GdVO4. Under a temperature of 1050 °C, Gd2Zr2O7 based coatings are more stable, both thermally and chemically, than YSZ, and exhibit a better hot corrosion resistance. 相似文献
124.
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126.
In this study we present Monte Carlo method for obtaining the time-resolved energy spectra of neutrons emitted by D-D reaction
in plasma focus devices. Angular positions of detectors obtained to maximum reconstruction of neutron spectrum. The detectors
were arranged over a range of 0–22.5 m from the source and also at 0°, 30°, 60°, and 90° with respect to the central axis.
The results show that an arrangement with five detectors placed at 0, 2, 7.5, 15 and 22.5 m around the central electrode of
plasma focus as an anisotropic neutron source is required. As it shown in reconstructed spectrum, the distance between the
neutron source and detectors is reduced and also the final reconstructed signal obtained with a very fine accuracy. 相似文献
127.
B. Jaleh M. Valieghbal S. Habibi M. J. Torkamany 《Journal of Superconductivity and Novel Magnetism》2012,25(8):2665-2669
Amorphous metallic alloys (AMAS) have found wide application in various fields. Laser is used to modify materials. In this work, we have prepared an amorphous metallic alloy with composition Fe77Co21Si2 using the melt spinning method. The prepared specimens have irradiated by a Nd:YAG laser at 1064?nm, with various fluences to investigate the corresponding induced change. The structures of specimens are verified by X-ray diffraction (XRD) before and after laser irradiated. Then magnetic parameters are measured using a vibrating sample magnetometer. Morphology reference and laser treated samples are investigated by the scanning electron microscope (SEM). The use of laser beam of relatively low energy, but with a subsequent overlapping of heated areas, resulted in a much more homogeneous structure in the heated areas of the ribbon. These measurements show that initially the magnetic properties are altered due to laser processing. The surface alteration was being simultaneously monitored by laser induced breakdown spectroscopy (LIBS). 相似文献
128.
Julien Fatisson Sania Mansouri Daniel Yacoub Yahye Merhi Maryam Tabrizian 《Journal of the Royal Society Interface》2011,8(60):988-997
Platelet adhesion and activation rates are frequently used to assess the thrombogenicity of biomaterials, which is a crucial step for the development of blood-contacting devices. Until now, electron and confocal microscopes have been used to investigate platelet activation but they failed to characterize this activation quantitatively and in real time. In order to overcome these limitations, quartz crystal microbalance with dissipation (QCM-D) was employed and an explicit time scale introduced in the dissipation versus frequency plots (Df–t) provided us with quantitative data at different stages of platelet activation. The QCM-D chips were coated with thrombogenic and non-thrombogenic model proteins to develop the methodology, further extended to investigate polymer thrombogenicity. Electron microscopy and immunofluorescence labelling were used to validate the QCM-D data and confirmed the relevance of Df–t plots to discriminate the activation rate among protein-modified surfaces. The responses showed the predominant role of surface hydrophobicity and roughness towards platelet activation and thereby towards polymer thrombogenicity. Modelling experimental data obtained with QCM-D with a Matlab code allowed us to define the rate at which mass change occurs (A/B), to obtain an A/B value for each polymer and correlate this value with polymer thrombogenicity. 相似文献
129.
Maryam Moshkelani Mariya Marinova Michel Perrier Jean Paris 《Applied Thermal Engineering》2013,50(2):1427-1436
Incorporating a biorefinery unit to an operating Kraft pulping process has significant technological, economic and social advantages over the construction of a grassroot biorefinery. Also, the conversion of a Kraft mill from total pulp making to complete biorefinery can be done in a stepwise fashion and so give a company that envisages such transformation the opportunity to master the new technologies, evaluate options and develop an appropriate business plan. In all cases however, the road to conversion presents serious challenges. As components of the wood such as lignin or hemicelluloses are withdrawn from the Kraft pulp line, the heat production capacity from the recovery boiler where they are currently burnt is diminished. At the same time the operation of the added biorefinery unit increases the steam demand. In order to avoid fossil fuel dependency, the total site must be highly integrated and optimized. The application of an intensive and innovative energy optimization methodology to actual case studies has shown that the green, low GHG emissions biorefinery is feasible. The economics can be attractive for a site combining specialty wood pulp and bio-product, biomass gasification, power cogeneration and heat upgrading by optimally positioned and designed absorption heat cycles. The methodology has been applied to biorefining technologies for lignin and hemicelluloses extraction and valorisation, both technologies being coupled with gasification of wood residue. 相似文献
130.