A three-dimensional Eulerian multiphase model, with closure law according to the kinetic theory of granular flow, was used to study the gas/solid flow behaviors in spout-fluid beds. The influences of the coefficient o...A three-dimensional Eulerian multiphase model, with closure law according to the kinetic theory of granular flow, was used to study the gas/solid flow behaviors in spout-fluid beds. The influences of the coefficient of restitution due to non-ideal particle collisions on the simulated results were tested. It is demonstrated that the simulated result is strongly affected by the coefficient of restitution. Comparison of simulations with experiments in a small spout-fluid bed showed that an appropriate coefficient of restitution of 0.93 was necessary to simulate the flow characteristics in an underdesigned large size of spout-fluid bed coal gasifier with diameter of lm and height of 6m. The internal jet and gas/solid flow patterns at different operating conditions were obtained. The simulations show that an optimal gas/solid flow pattern for coal gasification is found when the spouting gas flow rate is equal to the fluidizing gas flow rate and the total of them is two and a half times the minimum fluidizing gas flow rate. Besides, the radial distributions of particle velocity and gas velocity show similar tendencies; the radial distributions of particle phase pressure due to particle collisions and the particle pseudo-temperature corresponding to the macroscopic kinetic energy of the random particle motion also show similar tendencies. These indicate that both gas drag force and particle collisions dominate the movement of particles.展开更多
Considering the bad condition and shortage of medical resource in Sudan peacekeeping mission area, the author contrives the procedure of CASEVAC/MEDEVAC, including definition, request, authorization, operation and mis...Considering the bad condition and shortage of medical resource in Sudan peacekeeping mission area, the author contrives the procedure of CASEVAC/MEDEVAC, including definition, request, authorization, operation and miscellaneous, and stipulates the responsibility of parties concerned. The aim is to ensure systematic, organized and timely evacuation of patients to the most suitable medical facility for each individual case,thereby to minimize the loss of lives and limbs.展开更多
Perforin is a pore-forming protein engaged mainly in mediating target T cell death and is employed by cytotoxic T lymphocytes （CTLs） and natural killer cells. However, whether it also plays a role in conventional C...Perforin is a pore-forming protein engaged mainly in mediating target T cell death and is employed by cytotoxic T lymphocytes （CTLs） and natural killer cells. However, whether it also plays a role in conventional CD4^＋ T cell function remains unclear. Here we report that in perforin-deficient （PKO） mice, CD4^＋ T cells are hyperproliferative in response to T cell receptor （TCR） stimulation. This feature of hyperproliferation is accompanied by the enhancement both in cell division and in IL-2 secretion. It seems that the perforin deficiency does not influence T cell development in thymus spleen and lymph node. In vivo, perforin deficiency results in increased antigen-specific T cell proliferation and antibody production. Furthermore, PKO mice are more susceptible to experimental autoimmune uveitis. To address the molecular mechanism, we found that after TCR stimulation, CD4^＋ T cells from PKO mice display an increased intracellular calcium flux and subsequently enhance activation of transcription factor NFAT1. Our results indicate that perforin plays a negative role in regulating CD4^＋ T cell activation and immune response by affecting TCR-dependent Ca^2＋ signaling.展开更多
基金Supported by the National Key Program of Basic Research in China (No.2004CB217702, No.2005CB221202, No.2006CB20030201) and the National Natural Science Foundation of China (No.20590367, No.50676021, No.50606006).
文摘A three-dimensional Eulerian multiphase model, with closure law according to the kinetic theory of granular flow, was used to study the gas/solid flow behaviors in spout-fluid beds. The influences of the coefficient of restitution due to non-ideal particle collisions on the simulated results were tested. It is demonstrated that the simulated result is strongly affected by the coefficient of restitution. Comparison of simulations with experiments in a small spout-fluid bed showed that an appropriate coefficient of restitution of 0.93 was necessary to simulate the flow characteristics in an underdesigned large size of spout-fluid bed coal gasifier with diameter of lm and height of 6m. The internal jet and gas/solid flow patterns at different operating conditions were obtained. The simulations show that an optimal gas/solid flow pattern for coal gasification is found when the spouting gas flow rate is equal to the fluidizing gas flow rate and the total of them is two and a half times the minimum fluidizing gas flow rate. Besides, the radial distributions of particle velocity and gas velocity show similar tendencies; the radial distributions of particle phase pressure due to particle collisions and the particle pseudo-temperature corresponding to the macroscopic kinetic energy of the random particle motion also show similar tendencies. These indicate that both gas drag force and particle collisions dominate the movement of particles.
文摘Considering the bad condition and shortage of medical resource in Sudan peacekeeping mission area, the author contrives the procedure of CASEVAC/MEDEVAC, including definition, request, authorization, operation and miscellaneous, and stipulates the responsibility of parties concerned. The aim is to ensure systematic, organized and timely evacuation of patients to the most suitable medical facility for each individual case,thereby to minimize the loss of lives and limbs.
基金Acknowledgments We thank Drs Hua Gu （Columbia University, USA）, Weiguo Zhang （Duke University Medical Center, USA）, and Youhai H Chen （University of Pennsylvania, USA） for reviewing the manuscript and for suggestions, and Dr Ilia Voskoboinik （Peter MacCallum Cancer Centre, Australia） for providing the mouse perforin cDNA in pKS（＋） Bluescript. Ragl^-/- mice were gifts from Xiaolong Liu （Shanghai Institutes for Biological Sciences, China）. This work was supported by grants from the National Natural Science Foundation of China （30325018, 30530700, 30623003, and 30421005） and CAS project （KSCX1-YW-R-43）, grants from the National Key Project 973 （2006CB504300 and 2007CB512404）, grants from the Technology Commission of Shanghai Municipality （04DZ14902, 04DZ19108, 06DZ22032, 04DZ19112, 07XD14033, and 07DZ22916）, 863 key project （2006AA02A247）, and a grant from the E-institutes of Shanghai Universities Immunology Division.
文摘Perforin is a pore-forming protein engaged mainly in mediating target T cell death and is employed by cytotoxic T lymphocytes （CTLs） and natural killer cells. However, whether it also plays a role in conventional CD4^＋ T cell function remains unclear. Here we report that in perforin-deficient （PKO） mice, CD4^＋ T cells are hyperproliferative in response to T cell receptor （TCR） stimulation. This feature of hyperproliferation is accompanied by the enhancement both in cell division and in IL-2 secretion. It seems that the perforin deficiency does not influence T cell development in thymus spleen and lymph node. In vivo, perforin deficiency results in increased antigen-specific T cell proliferation and antibody production. Furthermore, PKO mice are more susceptible to experimental autoimmune uveitis. To address the molecular mechanism, we found that after TCR stimulation, CD4^＋ T cells from PKO mice display an increased intracellular calcium flux and subsequently enhance activation of transcription factor NFAT1. Our results indicate that perforin plays a negative role in regulating CD4^＋ T cell activation and immune response by affecting TCR-dependent Ca^2＋ signaling.
