4,688 research outputs found

    Neutrophil and lymphocyte responses to oral Streptococcus in Adamantiades-Behcet's disease

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    Immune reactions against microorganisms play an important pathogenic role in Adamantiades-Behçet’s disease (ABD). We had previously obtained Streptococcus sanguinis (strain BD113-20) isolated from the oral cavity of patients with ABD. To investigate the pathogenesis of this isolate, we examined neutrophil 5 reactions and level of cytokine production by lymphocytes after stimulation with the strain. The reactions of neutrophils were examined by chemiluminescence assay using whole blood. The amounts of interferon gamma (IFN-g) and interleukin (IL)-4, IL-8, IL-10, and IL-12 produced by peripheral blood mononuclear cells (PBMCs) were measured by ELISA. 10 Strain BD113-20 activated neutrophils from patients with ABD and healthy volunteers, and, in addition it increased IFN-g production by lymphocytes. Lymphocyte from the patients with ABD showed a dominant T helper 1 (Th-1) immune response. Results indicated that both bacterial stimulation and host hypersensitivity might be involved in the symptoms and pathogenesis of ABD

    Impact of Wind Generation on Transmission Voltage Support during Weak Grid

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    Today, there are concerns about the effects of high wind penetration on electric power system operations. This is due to the more distributed nature of wind turbine generation and the corresponding multi-path power flows on the electric power transmission grid. In particular, the higher line impendences associated with inverter-based wind generation results in larger voltage fluctuation under varying load. This may results in conditions where even after a fault condition has been cleared, the transmission system voltages may not recover. Therefore, this paper concentrates on the impact of weak grid condition for voltage instability. To approach it, a 6-bus system is created in Matlab/Simulink application, and voltage stability of each fault line is simulated. Through the computer-based experiments, voltage instability can be observed. Results show the impact on voltage stability and recovery in terms of the presence of wind generation levels

    Numerical study of transonic flow over oscillating airfoils using the full potential equation

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    The behavior of unsteady aerodynamic loadings on airfoils oscillating in transonic flow has been investigated numerically with particular attention given to supercritical airfoil sections. A previously developed finite difference method, which is based on the full potential equation and which uses a quasi-conservative scheme for proper capture of a shock wave motion, was employed for the present study. The unsteady aerodynamic pressure and load distributions on several different airfoil sections are presented with particular emphasis on the effects of free-stream Mach number, reduced frequency, and mean angle of attack. These parameters are demonstrated to have a significant effect on the behavior of the unsteady aerodynamic loadings. Comparisons of the present calculations with the exact inviscid solution and with the experimental results are also presented

    Analysis and Steps to Mitigate Heat Exchanger Fouling in an Aromatics Plant

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    A heat exchanger, upstream a distillation tower for the separation of BTX (benzene, toluene, xylene) from crude benzene in an aromatics plant, experiences heavy fouling. The fouling mechanism and countermeasures to mitigate or eliminate it, were investigated. An Alcor Hot Liquid Process Simulator (HLPS)was used for the fouling rate measurement. The main mechanism is a combination of precipitation fouling and chemical reaction fouling. Effects, such as temperature, vapor ratio (vapor mole fraction of the fluid), heater materials, surface roughness and the addition of some different types of chemicals were studied. From the experiments, some countermeasures for this fouling were proposed. A decrease in the vapor liquid ratio and a continuous supply of the more effective antifoulant chemical (dispersant) successfully reduced fouling in the plant

    Impact of Skeleton Imports on Hollowing Out Production Bases Outside Japan

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    Many Japanese manufacturing companieshave moved their production facilities partially orcompletely to China and other Asian countries, and theproducts produced at such oversea production bases arereversely imported into Japan. While this hollowing outproduction bases outside Japan enables them to reduce thelabor and other operation costs, it incurs the extra logisticscosts. In addition, the market lead time becomes inevitablylonger, resulting in the increased inventory costs. In order tocompensate these negative effects, certain Japanesecompanies have been implementing the SI (SkeletonImports) strategy, where a variety of products in smallquantity would be designed in such a way that a commonframe (called Skeleton) can be used for all the products andvarious product specifications can be mounted onto thecommon frame to produce a variety of products in smallquantity efficiently. The purpose of this paper is to analyzethe positive effects of the SI strategy via simulation
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