目的建立并评价分枝杆菌液体培养基质辅助激光解吸电离飞行时间质谱(matrix assisted laser desorption ionization time of flight mass spectrometry,MALDI-TOF MS)直接鉴定技术。方法收集2014年6月至2016年5月首都医科大学附属北京...目的建立并评价分枝杆菌液体培养基质辅助激光解吸电离飞行时间质谱(matrix assisted laser desorption ionization time of flight mass spectrometry,MALDI-TOF MS)直接鉴定技术。方法收集2014年6月至2016年5月首都医科大学附属北京同仁医院1 466例呼吸科住院患者痰标本,进行BactecTMMGITTM960分枝杆菌快速液体培养(简称液体培养),以其中报警并经萋-尼抗酸染色确认为抗酸杆菌的105例(无重复病例)为研究对象,对比本实验室自行设计并改良的"同仁"分枝杆菌液体培养直接鉴定法(培养液经特殊前处理后直接进行MALDI-TOF MS鉴定)及传统鉴定法(培养液转种于L-J固体培养基,得到菌落后再进行MALDI-TOF MS鉴定),并通过16S rRNA基因及16S^23S rRNA基因间隔区测序验证。结果以基因测序鉴定为金标准,液体培养直接鉴定与传统鉴定法结果一致率为100%;二者鉴定至属的准确率均为100%(105/105),鉴定至种的准确率均为99.05%(104/105)。液体培养后直接鉴定与传统鉴定法MALDI-TOF MS鉴定分值≥2.000分的比例差异无统计学意义(χ~2=2.952,P=0.086)。4例分值<1.700分的菌株谱图杂峰较多而有效峰较少。结论本实验室自行设计的"同仁"分枝杆菌液体培养MALDI-TOF MS直接鉴定法鉴定结果准确,缩短了分枝杆菌培养和鉴定的时间,且可保证生物安全,对分枝杆菌感染的快速诊断和及时治疗意义重大,适用于我国各级临床实验室。展开更多
In order to meet the demand of CubeSats for low power and high-performance micro-propulsion system,a porous ionic liquid electrospray thruster prototype is developed in this study.1010 conical emitter arrays are fabri...In order to meet the demand of CubeSats for low power and high-performance micro-propulsion system,a porous ionic liquid electrospray thruster prototype is developed in this study.1010 conical emitter arrays are fabricated on an area of 3.24 cm^(2) by computer numerical control machining technology.The propellant is 1-ethyl-3-methylimidazolium tetrafluoroborate.The over-all dimension of the assembled prototype is 3 cm×3 cm×1 cm,with a total weight of about 15 g(with propellant).The performance of this prototype is tested under vacuum.The results show that it can work in the voltage range of±2.0 kV to±3.0 kV,and the maximum emission current and input power are about 355 lA and 1.12 W.Time of Flight(TOF)mass spectrometry results show that cationic monomers and dimers dominate the beam in positive mode,while a higher proportion of higher-order solvated ion clusters in negative mode.The maximum specific impulse is 2992 s in positive mode and 849 s in negative mode.The thrust is measured in two methods:one is calculated by TOF results and the other is directly measured by high-precision torsional thrust stand.The thrust(T)obtained by these two methods conforms to a certain scaling law with respect to the emis-sion current(I_(em))and the applied voltage(V_(app)),following the scale of T-Iem_(Vapp)^(0.5),and the thrust range is from 2.1 lN to 42.6 lN.Many thruster performance parameters are significantly different in positive and negative modes.We speculate that due to the higher solvation energy of the anion,more solvated ion clusters are formed rather than pure ions under the same electric field.It may help to improve thruster performance if porous materials with smaller pore sizes are used as reservoirs.Although there are still many problems,most of the performance parameters of ILET-3 are good,which can theoretically meet the requirements of CubeSats for micro-propulsion system.展开更多
Constant fraction discriminator （CFD） is one of theoretic method which can locate timing point at same fraction of echo pulse in pulsed time-of-flight （TOF） laser rangefinding. In this paper, the theory of CFD met...Constant fraction discriminator （CFD） is one of theoretic method which can locate timing point at same fraction of echo pulse in pulsed time-of-flight （TOF） laser rangefinding. In this paper, the theory of CFD method was analyzed in reality condition. The design, simulation and printed-circuit-board （PCB） performance of CFD circuit were shown. Finally, an over amplified method was introduced, by which the influence of direct-current （DC） bias error could be reduced. The experimental results showed that timing discriminator could set the timing point to a certain point on echo pulse, which did not depend on the amplitude of echo pulse.展开更多
基金supported by the National Key R&D Program of China(No.2020YFC2201103).
文摘In order to meet the demand of CubeSats for low power and high-performance micro-propulsion system,a porous ionic liquid electrospray thruster prototype is developed in this study.1010 conical emitter arrays are fabricated on an area of 3.24 cm^(2) by computer numerical control machining technology.The propellant is 1-ethyl-3-methylimidazolium tetrafluoroborate.The over-all dimension of the assembled prototype is 3 cm×3 cm×1 cm,with a total weight of about 15 g(with propellant).The performance of this prototype is tested under vacuum.The results show that it can work in the voltage range of±2.0 kV to±3.0 kV,and the maximum emission current and input power are about 355 lA and 1.12 W.Time of Flight(TOF)mass spectrometry results show that cationic monomers and dimers dominate the beam in positive mode,while a higher proportion of higher-order solvated ion clusters in negative mode.The maximum specific impulse is 2992 s in positive mode and 849 s in negative mode.The thrust is measured in two methods:one is calculated by TOF results and the other is directly measured by high-precision torsional thrust stand.The thrust(T)obtained by these two methods conforms to a certain scaling law with respect to the emis-sion current(I_(em))and the applied voltage(V_(app)),following the scale of T-Iem_(Vapp)^(0.5),and the thrust range is from 2.1 lN to 42.6 lN.Many thruster performance parameters are significantly different in positive and negative modes.We speculate that due to the higher solvation energy of the anion,more solvated ion clusters are formed rather than pure ions under the same electric field.It may help to improve thruster performance if porous materials with smaller pore sizes are used as reservoirs.Although there are still many problems,most of the performance parameters of ILET-3 are good,which can theoretically meet the requirements of CubeSats for micro-propulsion system.
基金This work was sponsored by the National Natural Science Foundation of China （Grant No. 40801123）.
文摘Constant fraction discriminator （CFD） is one of theoretic method which can locate timing point at same fraction of echo pulse in pulsed time-of-flight （TOF） laser rangefinding. In this paper, the theory of CFD method was analyzed in reality condition. The design, simulation and printed-circuit-board （PCB） performance of CFD circuit were shown. Finally, an over amplified method was introduced, by which the influence of direct-current （DC） bias error could be reduced. The experimental results showed that timing discriminator could set the timing point to a certain point on echo pulse, which did not depend on the amplitude of echo pulse.
基金Supported by the National Nature Science Foundation of China (30 2 716 1730 0 70 913) and Beijing Science andTechnology Commission Project (H0 10 2 10 2 2 0 113)
