Recently, the effect of ligand receptor interaction on the membrane structure of liposomes has been studied extensively. However, little is known about how it exists on biological membranes. In this paper, the effect ...Recently, the effect of ligand receptor interaction on the membrane structure of liposomes has been studied extensively. However, little is known about how it exists on biological membranes. In this paper, the effect of Con-canavalin A (ConA) receptor interaction on the structure of cell membranes was studied by Circular Dichroism (CD) and 3lP Nuclear Magnetic Resonance (NMR).CD results of both the purified macrophage membranes and human erythrocyte ghosts (EG) showed that the conformation of membrane proteins changed after ConA bind ing.For further research, 31P-NMR was used to detect the organization of phospholipid molecules on macrophage mem branes. After ConA binding, the tendency to form non bi-layer structure increased with the amount of ConA. The changes of 31P-NMR spectra of living macrophages might be partly due to the above stated reason too.In addition, ConA-receptor interaction also induced similar results of 31P-NMR spectra in EG. In contrast, wheat germ agglutinin (WGA ), another kind of lectin, rarely showed the same influence.展开更多
为完善拱形明洞结构可靠性设计方法,利用模型试验、数值模拟及理论分析等,结合现场实际,开展了落石冲击下无回填土拱形明洞破坏特征及失效模式、极限承载力、落石冲击荷载及极限状态表达式等的研究.首先,根据落石冲击下无回填土拱形明...为完善拱形明洞结构可靠性设计方法,利用模型试验、数值模拟及理论分析等,结合现场实际,开展了落石冲击下无回填土拱形明洞破坏特征及失效模式、极限承载力、落石冲击荷载及极限状态表达式等的研究.首先,根据落石冲击下无回填土拱形明洞结构失效破坏特征,将结构局部失效范围部分简化为四边固支方形钢筋混凝土板结构,利用塑性极限原理按刚塑性板进行准静态极限荷载计算,得到结构极限承载力即抗力;其次,将离散元颗粒流数值模拟方法得到的落石冲击力最大峰值作为钢筋混凝土板顶部落石冲击力,通过回归分析,得到用落石重力势能的幂函数表示的落石冲击荷载表达式;再次,将得到的结构抗力与落石冲击荷载联立得到极限状态方程,利用MABLAB软件编程求得结构可靠指标,通过与目标可靠指标的比较,进行结构可靠度设计与优化;最后,利用所建立的结构可靠度设计方法,对某客专双线拱形明洞设计进行了可靠度检算.研究结果表明:当落石高度为5~15 m、落石重量为1~2 k N时,原设计明洞结构可靠指标可达到4.2;当将原设计的C35混凝土调整为C40,钢筋由HRB335调整为HRB500后,落石高度为5~20 m、落石重量为1~2 k N范围时的结构可靠指标可达到5.4以上.展开更多
文摘Recently, the effect of ligand receptor interaction on the membrane structure of liposomes has been studied extensively. However, little is known about how it exists on biological membranes. In this paper, the effect of Con-canavalin A (ConA) receptor interaction on the structure of cell membranes was studied by Circular Dichroism (CD) and 3lP Nuclear Magnetic Resonance (NMR).CD results of both the purified macrophage membranes and human erythrocyte ghosts (EG) showed that the conformation of membrane proteins changed after ConA bind ing.For further research, 31P-NMR was used to detect the organization of phospholipid molecules on macrophage mem branes. After ConA binding, the tendency to form non bi-layer structure increased with the amount of ConA. The changes of 31P-NMR spectra of living macrophages might be partly due to the above stated reason too.In addition, ConA-receptor interaction also induced similar results of 31P-NMR spectra in EG. In contrast, wheat germ agglutinin (WGA ), another kind of lectin, rarely showed the same influence.
文摘为完善拱形明洞结构可靠性设计方法,利用模型试验、数值模拟及理论分析等,结合现场实际,开展了落石冲击下无回填土拱形明洞破坏特征及失效模式、极限承载力、落石冲击荷载及极限状态表达式等的研究.首先,根据落石冲击下无回填土拱形明洞结构失效破坏特征,将结构局部失效范围部分简化为四边固支方形钢筋混凝土板结构,利用塑性极限原理按刚塑性板进行准静态极限荷载计算,得到结构极限承载力即抗力;其次,将离散元颗粒流数值模拟方法得到的落石冲击力最大峰值作为钢筋混凝土板顶部落石冲击力,通过回归分析,得到用落石重力势能的幂函数表示的落石冲击荷载表达式;再次,将得到的结构抗力与落石冲击荷载联立得到极限状态方程,利用MABLAB软件编程求得结构可靠指标,通过与目标可靠指标的比较,进行结构可靠度设计与优化;最后,利用所建立的结构可靠度设计方法,对某客专双线拱形明洞设计进行了可靠度检算.研究结果表明:当落石高度为5~15 m、落石重量为1~2 k N时,原设计明洞结构可靠指标可达到4.2;当将原设计的C35混凝土调整为C40,钢筋由HRB335调整为HRB500后,落石高度为5~20 m、落石重量为1~2 k N范围时的结构可靠指标可达到5.4以上.
