Single cylindrical submicron pores in PMMA polymer membranes are micropatterned by electron beam lithography and integrated into all PMMA-based electrophoretic flow detector systems. Pore dimensions are 450 nm in diam...Single cylindrical submicron pores in PMMA polymer membranes are micropatterned by electron beam lithography and integrated into all PMMA-based electrophoretic flow detector systems. Pore dimensions are 450 nm in diameter and 1 μm in length. The pores are electrically characterized in aqueous KCl electrolyte, exhibiting a stable time-independent ionic current through the pore with a noise level of less than 1% of the open-pore current. The current-voltage curves are linear and scale with electrolyte concentration. The negative surface charge of the membrane over-proportionally decreases pore conductance at low electrolyte concentrations (≤0.1 M) that are still beyond those typically applied in biological experiments. Pores do not exhibit rectification of current flowing through them, allowing for operation with either polarity. To allow for detection of yet much smaller particles, the described PMMA-based system also was successfully equipped with pores of 1.5 nm instead of 450 nm in diameter. This was achieved by introducing naturally occurring biological protein pores of α-hemolysin on a lipid bilayer into the prepatterned PMMA membrane of an assembled PMMA-based electrophoretic flow detector system. Characteristics of translocation events of single-stranded linear plasmid DNA molecules through the pores were recorded, and ionic current deductions during biomolecule translocation were clear and distinguished. Based on the presented submicron scale open pore ionic current transport properties, as well as the observed passage of DNA molecules through protein pores inserted into PMMA membranes, our current research proposes that all PMMA electrophoretic flow detectors exhibit an excellent potential for future use as biomedical resistive-pulse sensors, as long as pore dimensions match those of biomolecules to be detected.展开更多
结合无锡地铁1、2号线中电气火灾监控系统的设计、施工、调试、运营等情况,阐述城市轨道交通电气火灾监控系统的具体设计方案,主要包括系统设置范围的变电所400 V柜及环控电控柜出线;系统预警和报警整定值300 m A和500 m A;系统直接与...结合无锡地铁1、2号线中电气火灾监控系统的设计、施工、调试、运营等情况,阐述城市轨道交通电气火灾监控系统的具体设计方案,主要包括系统设置范围的变电所400 V柜及环控电控柜出线;系统预警和报警整定值300 m A和500 m A;系统直接与综合监控系统做通信接口等。另外,还指出城市轨道交通电气火灾监控系统在实际设计和施工过程中需要注意的事项,主要包括在设计中只对故障回路进行检测、报警而不联动故障回路断路器跳闸,建议选择一体式监控探测器并且事先预留安装位置等;在施工中N线需穿过探测器,而PE线则不能穿过探测器等,为后续城市轨道交通电气火灾监控系统的设计和施工提供参考。展开更多
文摘Single cylindrical submicron pores in PMMA polymer membranes are micropatterned by electron beam lithography and integrated into all PMMA-based electrophoretic flow detector systems. Pore dimensions are 450 nm in diameter and 1 μm in length. The pores are electrically characterized in aqueous KCl electrolyte, exhibiting a stable time-independent ionic current through the pore with a noise level of less than 1% of the open-pore current. The current-voltage curves are linear and scale with electrolyte concentration. The negative surface charge of the membrane over-proportionally decreases pore conductance at low electrolyte concentrations (≤0.1 M) that are still beyond those typically applied in biological experiments. Pores do not exhibit rectification of current flowing through them, allowing for operation with either polarity. To allow for detection of yet much smaller particles, the described PMMA-based system also was successfully equipped with pores of 1.5 nm instead of 450 nm in diameter. This was achieved by introducing naturally occurring biological protein pores of α-hemolysin on a lipid bilayer into the prepatterned PMMA membrane of an assembled PMMA-based electrophoretic flow detector system. Characteristics of translocation events of single-stranded linear plasmid DNA molecules through the pores were recorded, and ionic current deductions during biomolecule translocation were clear and distinguished. Based on the presented submicron scale open pore ionic current transport properties, as well as the observed passage of DNA molecules through protein pores inserted into PMMA membranes, our current research proposes that all PMMA electrophoretic flow detectors exhibit an excellent potential for future use as biomedical resistive-pulse sensors, as long as pore dimensions match those of biomolecules to be detected.
文摘结合无锡地铁1、2号线中电气火灾监控系统的设计、施工、调试、运营等情况,阐述城市轨道交通电气火灾监控系统的具体设计方案,主要包括系统设置范围的变电所400 V柜及环控电控柜出线;系统预警和报警整定值300 m A和500 m A;系统直接与综合监控系统做通信接口等。另外,还指出城市轨道交通电气火灾监控系统在实际设计和施工过程中需要注意的事项,主要包括在设计中只对故障回路进行检测、报警而不联动故障回路断路器跳闸,建议选择一体式监控探测器并且事先预留安装位置等;在施工中N线需穿过探测器,而PE线则不能穿过探测器等,为后续城市轨道交通电气火灾监控系统的设计和施工提供参考。
