An extrusion-ploughing process was presented to fabricate the integral fin function-surface. Cutting edge inclination angle and rake angle can be calculated from the tool’s geometry relationship. The description of f...An extrusion-ploughing process was presented to fabricate the integral fin function-surface. Cutting edge inclination angle and rake angle can be calculated from the tool’s geometry relationship. The description of fins’ geometry characters was standardized. The experiments show that, when the middle cutting edge’s inclination angle η is less than 35°, continuous fin will come out; when η is between 35° and 55°, the fins will be saw-tooth ones, and the fins will be torn when this angle is above 55°; when the extrusion angle θ is between 60° and 150°, the fins will appear, or else, the fins will be torn into chips from the base. Forming angle and clearance angle have little effect on fin’s formation. For continuous fin, its height is close to cutting depth when it is small, but it will become approximately constant as cutting depth grows; for saw-tooth fins, the width, the height, as well as the clearance will increase with the increase of cutting depth, but the increment of clearance is small; neither for continuous fin, nor for saw-tooth ones, cutting velocity has little influence on their structure parameters.展开更多
The formation mechanism of methane （CH4） during coal evolution has been investigated by density functional theory （DFT） of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of med...The formation mechanism of methane （CH4） during coal evolution has been investigated by density functional theory （DFT） of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of medium rank coal, is the main source of coalbed methane （CBM）. Ethylbenzene （A） and 6,7-dimethyl-5,6,7,8-tetrahydro-1-hydroxynaphthalene （B） have been used as model compounds to study the pyrolysis mechanism of highly volatile bituminous coal （R）, according to the similarity of bond orders and bond lengths. All possible paths are designed for each model. It can be concluded that the activation energies for H-assisted paths are lower than others in the process of methane formation; an H radical attacking on β-C to yield CH4 is the dominant path for the formation of CH4 from highly volatile bituminous coal. In addition, the calculated results also reveal that the positions on which H radical attacks and to which intramolecular H migrates have effects on methyl cleavage.展开更多
To screen for additional treatment targets against tongue cancer, we evaluated the contributions of extracellular signal-related kinase(ERK), AKT and ezrin in cancer development. Immunohistochemical staining showed th...To screen for additional treatment targets against tongue cancer, we evaluated the contributions of extracellular signal-related kinase(ERK), AKT and ezrin in cancer development. Immunohistochemical staining showed that ERK and ezrin expressions were significantly higher in invasive squamous cell carcinoma than in carcinoma in situ. To investigate the roles of ERK and ezrin in cancer development, we used the non-woven silica fibre sheet Cellbedwith a structure resembling the loose connective tissue morphology in a novel 3 D culture system. We confirmed that the 3 D system using CellbedTMaccurately mimicked cancer cell morphology in vivo. Furthermore, cell projections were much more apparent in 3 D-cultured tongue cancer cell lines than in 2 D cultures. Typically, under conventional 2 D culture conditions, F-actin and cortactin are colocalized in the form of puncta within cells.However, in the 3 D-cultured cells, colocalization was mainly observed at the cell margins, including the projections. Projections containing F-actin and cortactin colocalization were predicted to be invadopodia. Although suppressing ezrin expression with small interfering RNA transfection caused no marked changes in morphology, cell projection formation was decreased, and the tumour thickness in vertical sections after 3 D culture was markedly decreased after suppressing ERK activity because both the invasion ability and proliferation were inhibited. An association between cortactin activation as well as ERK activity and invadopodia formation was detected. Our novel 3 D culture systems using Cellbed? are simple and useful for in vitro studies before conducting animal experiments. ERK contributes to tongue cancer development by increasing both cancer cell proliferation and migration via cortactin activation.展开更多
Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O3-5 （LSGM） with various crystal symmetries （cubic, rhombohedral, orthorhombic, and monoclinic） are studied by employing first-principles calculations ...Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O3-5 （LSGM） with various crystal symmetries （cubic, rhombohedral, orthorhombic, and monoclinic） are studied by employing first-principles calculations based on density functional theory （DFT）. It is shown that the cubic LSGM has the smallest band gap, oxygen vacancy formation energy, and migration barrier, while the other three structures give rise to much larger values for these quantities, implying the best oxygen ion conductivity of the cubic LSGM among the four crystal structures. In out calculations, one oxygen vacancy migration pathway is considered in the cubic and rhombohedral structures due to all the oxygen sites being equivalent in them, while two vacancy migration pathways with different migration barriers are found in the orthorhombic and monoclinic symmetries owing to the existence of nonequivalent O1 and 02 oxygen sites. The migration energies along the migration pathway linking the two 02 sites are obviously lower than those along the pathway linking the O1 and 02 sites. Considering the phase transitions at high temperatures, the results obtained in this paper can not only explain the experimentally observed different behaviours of the oxygen ionic conductivity of LSGM with different symmetries, but also predict the rational crystal structures of LSGM for solid oxide fuel cell applications.展开更多
针对四旋翼无人机队形保持、编队避障问题,在双向、时不变通信拓扑结构下,基于领航跟随策略,利用安全攸关模型预测控制(safety-critical model predictive control,S-MPC)和一致性理论,设计编队控制器并实现了具有避障能力的队形保持。...针对四旋翼无人机队形保持、编队避障问题,在双向、时不变通信拓扑结构下,基于领航跟随策略,利用安全攸关模型预测控制(safety-critical model predictive control,S-MPC)和一致性理论,设计编队控制器并实现了具有避障能力的队形保持。采用分散式S-MPC算法,每架无人机在满足避碰条件无人机的可行区域内,仅规划自身运动来跟踪编队控制算法指定的轨迹。研究了各解耦后的无人机如何与其他无人机并行求解带有耦合约束的优化问题,从而保证了各无人机独立决策的一致性。同时,所提算法将控制障碍函数(control barrier function,CBF)引入到MPC控制器的约束中,从而保证无人机飞行在远离障碍物的安全集合内,规划出的轨迹更为平滑,减小了系统能耗。最后,通过仿真实验验证了所提方法的有效性。展开更多
基金Projects(50436010 50375055) supported by the National Natural Science Foundation of China+1 种基金 Project(04105942) supported by the Natural Science Foundation of Guangdong Province, China Project(2005B10201002) supported by Scientific and Technological Project of Guangdong Province, China
文摘An extrusion-ploughing process was presented to fabricate the integral fin function-surface. Cutting edge inclination angle and rake angle can be calculated from the tool’s geometry relationship. The description of fins’ geometry characters was standardized. The experiments show that, when the middle cutting edge’s inclination angle η is less than 35°, continuous fin will come out; when η is between 35° and 55°, the fins will be saw-tooth ones, and the fins will be torn when this angle is above 55°; when the extrusion angle θ is between 60° and 150°, the fins will appear, or else, the fins will be torn into chips from the base. Forming angle and clearance angle have little effect on fin’s formation. For continuous fin, its height is close to cutting depth when it is small, but it will become approximately constant as cutting depth grows; for saw-tooth fins, the width, the height, as well as the clearance will increase with the increase of cutting depth, but the increment of clearance is small; neither for continuous fin, nor for saw-tooth ones, cutting velocity has little influence on their structure parameters.
基金supported by the Major Projects of National Science and Technology(Grant No.2011ZX05040-005-002-001)the National Natural Science Foundation of China(Grant No.21276171 and 21276003)+1 种基金the National Younger Natural Science Foundation of China(Grant No.21103120)China Postdoctoral Science Foundation(Grant No.2012M520608)
文摘The formation mechanism of methane （CH4） during coal evolution has been investigated by density functional theory （DFT） of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of medium rank coal, is the main source of coalbed methane （CBM）. Ethylbenzene （A） and 6,7-dimethyl-5,6,7,8-tetrahydro-1-hydroxynaphthalene （B） have been used as model compounds to study the pyrolysis mechanism of highly volatile bituminous coal （R）, according to the similarity of bond orders and bond lengths. All possible paths are designed for each model. It can be concluded that the activation energies for H-assisted paths are lower than others in the process of methane formation; an H radical attacking on β-C to yield CH4 is the dominant path for the formation of CH4 from highly volatile bituminous coal. In addition, the calculated results also reveal that the positions on which H radical attacks and to which intramolecular H migrates have effects on methyl cleavage.
文摘To screen for additional treatment targets against tongue cancer, we evaluated the contributions of extracellular signal-related kinase(ERK), AKT and ezrin in cancer development. Immunohistochemical staining showed that ERK and ezrin expressions were significantly higher in invasive squamous cell carcinoma than in carcinoma in situ. To investigate the roles of ERK and ezrin in cancer development, we used the non-woven silica fibre sheet Cellbedwith a structure resembling the loose connective tissue morphology in a novel 3 D culture system. We confirmed that the 3 D system using CellbedTMaccurately mimicked cancer cell morphology in vivo. Furthermore, cell projections were much more apparent in 3 D-cultured tongue cancer cell lines than in 2 D cultures. Typically, under conventional 2 D culture conditions, F-actin and cortactin are colocalized in the form of puncta within cells.However, in the 3 D-cultured cells, colocalization was mainly observed at the cell margins, including the projections. Projections containing F-actin and cortactin colocalization were predicted to be invadopodia. Although suppressing ezrin expression with small interfering RNA transfection caused no marked changes in morphology, cell projection formation was decreased, and the tumour thickness in vertical sections after 3 D culture was markedly decreased after suppressing ERK activity because both the invasion ability and proliferation were inhibited. An association between cortactin activation as well as ERK activity and invadopodia formation was detected. Our novel 3 D culture systems using Cellbed? are simple and useful for in vitro studies before conducting animal experiments. ERK contributes to tongue cancer development by increasing both cancer cell proliferation and migration via cortactin activation.
基金supported by the National Natural Science Foundation of China (Grant No.10974183)
文摘Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O3-5 （LSGM） with various crystal symmetries （cubic, rhombohedral, orthorhombic, and monoclinic） are studied by employing first-principles calculations based on density functional theory （DFT）. It is shown that the cubic LSGM has the smallest band gap, oxygen vacancy formation energy, and migration barrier, while the other three structures give rise to much larger values for these quantities, implying the best oxygen ion conductivity of the cubic LSGM among the four crystal structures. In out calculations, one oxygen vacancy migration pathway is considered in the cubic and rhombohedral structures due to all the oxygen sites being equivalent in them, while two vacancy migration pathways with different migration barriers are found in the orthorhombic and monoclinic symmetries owing to the existence of nonequivalent O1 and 02 oxygen sites. The migration energies along the migration pathway linking the two 02 sites are obviously lower than those along the pathway linking the O1 and 02 sites. Considering the phase transitions at high temperatures, the results obtained in this paper can not only explain the experimentally observed different behaviours of the oxygen ionic conductivity of LSGM with different symmetries, but also predict the rational crystal structures of LSGM for solid oxide fuel cell applications.
