Objectives: To quantitatively study the adhesive pro- perties of hepatoma cells to collagen Ⅳ coated artifi- cial basement membrane and to investigate the rele- vance of cell adhesive forces to the concentration of c...Objectives: To quantitatively study the adhesive pro- perties of hepatoma cells to collagen Ⅳ coated artifi- cial basement membrane and to investigate the rele- vance of cell adhesive forces to the concentration of collagen Ⅳ. Methods: Synchronous G1 and S phase cells were a- chieved using thymine-2-desoxyriboside and cochicine sequential blockage method and double thymine-2- desoxyriboside blockage method respectively. The adhesive forces of hepatoma cells were investigated by micropipette aspiration technique. Results: The adhesive forces of hepatoma cells to ar- tificial basement membrane were (107.78±65.44) ×10^(-10)N, (182.60±107.88)×10^(-10)N, (298.91± 144.13)×10^(-10)N when the concentration of the membrane coated by 1, 2, 5μg/ml collagen Ⅳ re- spectively (P<0.001). The adhesive forces of G1 and S phases hepatoma cells to artificial basement membrane were (275.86±232.80)×10^(-10)N and (161.16±120.40)×10^(-10)N respectively when the concentration of the membrane coated by 5μg/ml collagen Ⅳ (P<0.001). Conclusions: The adhesive forces of hepatoma cells to artifical basement membrane in direct proportion to the concentration of collagen Ⅳ suggests that the in- crease of basement membrane might be conducive to the chemotactic motion and adhesiveness of tumor cells. G1 phase cells are more capable of adhering to basement membrane than S phase cells. Hepatoma cells, especially G1 phase cells, may survive in blood circulation, and sequest and adhere in microcircula- tion, and get through basement membrane for re- mote metastasis.展开更多
Event detection is one of the major applications of wireless sensor networks （WSNs）. Most of existing medium access control （MAC） protocols are mainly optimized for the situation under which an event only generate...Event detection is one of the major applications of wireless sensor networks （WSNs）. Most of existing medium access control （MAC） protocols are mainly optimized for the situation under which an event only generates one packet on a single sensor node. When an event generates multiple packets on a single node, the performance of these MAC protocols degrades rapidly. In this paper, we present a new synchronous duty-cycle MAC protocol called SR-MAC for the event detection applications in which multiple packets are generated on a single node. SR-MAC introduces a new scheduling mechanism that reserves few time slots during the SLEEP period for the nodes to transmit multiple packets. By this approach, SR-MAC can schedule multiple packets generated by an event on a single node to be forwarded over multiple hops in one operational cycle without collision. We use event delivery latency （EDL） and event delivery ratio （EDR） to measure the event detection capability of the SR-MAC protocol. Through detailed ns-2 simulation, the results show that SR-MAC can achieve lower EDL, higher EDR and higher network throughput with guaranteed energy efficiency compared with R-MAC, DW-MAC and PR-MAC.展开更多
In this paper, the mathematical dynamical model of a PEMFC （proton exchange membrane fuel cells） stack, integrated with an automotive synchronous electrical power drive, developed in Matlab environment, is shown. Lo...In this paper, the mathematical dynamical model of a PEMFC （proton exchange membrane fuel cells） stack, integrated with an automotive synchronous electrical power drive, developed in Matlab environment, is shown. Lots of simulations have been executed in many load conditions. In this paper, the load conditions regarding an electrical vehicle for disabled people is reported. The innovation in this field concerns the integration, in the PEMFC stack mathematical dynamic model, of a synchronous electrical power drive for automotive purposes. Goal of the simulator design has been to create an useful tool which is able to evaluate the behaviour of the whole system so as to optimize the components choose. As regards the simulations with a synchronous electrical power drive, the complete mathematical model allows to evaluate the PEMFC stack performances and electrochemical efficiency.展开更多
基金This work was supported by a grant from the National Natural Science Foundation of China (No. 39500037).
文摘Objectives: To quantitatively study the adhesive pro- perties of hepatoma cells to collagen Ⅳ coated artifi- cial basement membrane and to investigate the rele- vance of cell adhesive forces to the concentration of collagen Ⅳ. Methods: Synchronous G1 and S phase cells were a- chieved using thymine-2-desoxyriboside and cochicine sequential blockage method and double thymine-2- desoxyriboside blockage method respectively. The adhesive forces of hepatoma cells were investigated by micropipette aspiration technique. Results: The adhesive forces of hepatoma cells to ar- tificial basement membrane were (107.78±65.44) ×10^(-10)N, (182.60±107.88)×10^(-10)N, (298.91± 144.13)×10^(-10)N when the concentration of the membrane coated by 1, 2, 5μg/ml collagen Ⅳ re- spectively (P<0.001). The adhesive forces of G1 and S phases hepatoma cells to artificial basement membrane were (275.86±232.80)×10^(-10)N and (161.16±120.40)×10^(-10)N respectively when the concentration of the membrane coated by 5μg/ml collagen Ⅳ (P<0.001). Conclusions: The adhesive forces of hepatoma cells to artifical basement membrane in direct proportion to the concentration of collagen Ⅳ suggests that the in- crease of basement membrane might be conducive to the chemotactic motion and adhesiveness of tumor cells. G1 phase cells are more capable of adhering to basement membrane than S phase cells. Hepatoma cells, especially G1 phase cells, may survive in blood circulation, and sequest and adhere in microcircula- tion, and get through basement membrane for re- mote metastasis.
基金supported the National Natural Science Foundation of China under Grant No. 61103011
文摘Event detection is one of the major applications of wireless sensor networks （WSNs）. Most of existing medium access control （MAC） protocols are mainly optimized for the situation under which an event only generates one packet on a single sensor node. When an event generates multiple packets on a single node, the performance of these MAC protocols degrades rapidly. In this paper, we present a new synchronous duty-cycle MAC protocol called SR-MAC for the event detection applications in which multiple packets are generated on a single node. SR-MAC introduces a new scheduling mechanism that reserves few time slots during the SLEEP period for the nodes to transmit multiple packets. By this approach, SR-MAC can schedule multiple packets generated by an event on a single node to be forwarded over multiple hops in one operational cycle without collision. We use event delivery latency （EDL） and event delivery ratio （EDR） to measure the event detection capability of the SR-MAC protocol. Through detailed ns-2 simulation, the results show that SR-MAC can achieve lower EDL, higher EDR and higher network throughput with guaranteed energy efficiency compared with R-MAC, DW-MAC and PR-MAC.
文摘In this paper, the mathematical dynamical model of a PEMFC （proton exchange membrane fuel cells） stack, integrated with an automotive synchronous electrical power drive, developed in Matlab environment, is shown. Lots of simulations have been executed in many load conditions. In this paper, the load conditions regarding an electrical vehicle for disabled people is reported. The innovation in this field concerns the integration, in the PEMFC stack mathematical dynamic model, of a synchronous electrical power drive for automotive purposes. Goal of the simulator design has been to create an useful tool which is able to evaluate the behaviour of the whole system so as to optimize the components choose. As regards the simulations with a synchronous electrical power drive, the complete mathematical model allows to evaluate the PEMFC stack performances and electrochemical efficiency.
