One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific object...One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific objectives,measurement targets,and measurement requirements for the proposed Gas and Ion Analyzer(GIA).The GIA is designed for in-situ mass spectrometry of neutral gases and low-energy ions,such as hydrogen,carbon,and oxygen,in the vicinity of 311P.Ion sampling techniques are essential for the GIA's Time-of-Flight(TOF)mass analysis capabilities.In this paper,we present an enhanced ion sampling technique through the development of an ion attraction model and an ion source model.The ion attraction model demonstrates that adjusting attraction grid voltage can enhance the detection efficiency of low-energy ions and mitigate the repulsive force of ions during sampling,which is influenced by the satellite's surface positive charging.The ion source model simulates the processes of gas ionization and ion multiplication.Simulation results indicate that the GIA can achieve a lower pressure limit below 10-13Pa and possess a dynamic range exceeding 10~9.These performances ensure the generation of ions with stable and consistent current,which is crucial for high-resolution and broad dynamic range mass spectrometer analysis.Preliminary testing experiments have verified GIA's capability to detect gas compositions such as H2O and N2.In-situ measurements near 311P using GIA are expected to significantly contribute to our understanding of asteroid activity mechanisms,the evolution of the atmospheric and ionized environments of main-belt comets,the interactions with solar wind,and the origin of Earth's water.展开更多
An experimental technique for research on spherical divergent wave propagation in a solid has been developed, in which the source of generating spherical wave is a center initiating explosive charge designed in a mini...An experimental technique for research on spherical divergent wave propagation in a solid has been developed, in which the source of generating spherical wave is a center initiating explosive charge designed in a mini-spherical shape with yield equivalent to 0.125?g and 0.486?g TNT and a set of circular electromagnetic particle velocity gages is used to record the particle velocity histories. By using the circular electromagnetic particle velocity gages, the signal outputs not only are unattenuated due to the geometrical divergence, but also represent the average of the measured dynamic states of the medium over a circle on the wavefront. The distinctive features of this technique are very useful for the study of spherical divergent wave propagation in a solid, especially in an inhomogeneous solid, and the corresponding material dynamics. Many experimental measurements were conducted in polymethylmethacrylate (PMMA) and granite by means of the technique, and the reproducibility of tests was shown to be good. The measurement technique of the circular electromagnetic particle velocity gages is also suitable to the case of cylindrical wave.展开更多
目的应用定量CT(quantitative computed tomography,QCT)技术测量腰椎骨密度(bone mineral density,BMD),探讨体格测量、体成分分析指标与中老年男性腰椎BMD的相关性。方法本研究为横断面研究,选取2018年1月至2023年2月在河南省人民医...目的应用定量CT(quantitative computed tomography,QCT)技术测量腰椎骨密度(bone mineral density,BMD),探讨体格测量、体成分分析指标与中老年男性腰椎BMD的相关性。方法本研究为横断面研究,选取2018年1月至2023年2月在河南省人民医院健康管理中心接受体格检查的1152名中老年男性体检者为研究对象,采集受试者年龄、身高、体重、血压、腰围、臀围、体脂肪质量与体肌肉质量数据,并计算体质量指数(body mass index,BMI)、体脂率(body fat percentage,BFP)与骨骼肌质量指数(skeletal muscle mass index,SMI)。同时使用QCT技术测量受试者腰椎BMD值,按照BMI进行分组,分为BMI正常组(18.5≤BMI<24 kg/m^(2))、超重及肥胖组(BMI为>24 kg/m^(2)),并在两组中分别按照骨量诊断标准进行讨论。采用单因素方差分析,Pearson相关性分析和偏相关分析体格测量、体成分分析指标与腰椎BMD的相关性。结果在BMI正常组中,骨质疏松组的年龄、收缩压、腰臀比、BFP显著高于骨量正常组,SMI显著低于骨量正常组与骨量减少组(P均<0.05);超重及肥胖组中,骨质疏松组的年龄、收缩压、腰围、腰臀比与BFP显著高于骨量正常组,SMI显著低于骨量正常组与骨量减少组(P均<0.05)。Pearson相关性分析结果显示,BMI正常组中腰椎BMD值与年龄、腰围、腰臀比、BFP呈显著负相关关系(r=-0.385,r=-0.122,r=-0.199,r=-0.168,P均<0.05),与SMI呈正相关(r=0.226,P<0.05);超重及肥胖组中腰椎BMD值与年龄、收缩压、腰围、腰臀比、BFP呈显著负相关关系(r=-0.379,r=-0.087,r=-0.101,r=-0.187,r=-0.199,P均<0.05),与SMI呈正相关(r=0.251,P<0.05)。在校正年龄因素后,偏相关分析分析结果显示,BMI正常组中腰椎BMD值与腰围、腰臀比、BFP呈显著负相关关系(r=-0.157,r=-0.212,r=-0.134,P均<0.05),与SMI呈正相关(r=0.167,P<0.05);超重及肥胖组中腰椎BMD值与腰围、腰臀比、BFP呈显著负相关关系(r=-0.120,r=-0.163,r=-0.126,P均<0.05),与SMI呈正相关(r=0.159,P<0.05)。结论腰围、腰臀比、BFP、SMI与中老年男性体检人群腰椎BMD值密切相关,对肥胖和骨质疏松症的预防与管理具有一定临床价值。展开更多
基金Supported by the National Natural Science Foundation of China(42474239,41204128)China National Space Administration(Pre-research project on Civil Aerospace Technologies No.D010301)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA17010303)。
文摘One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific objectives,measurement targets,and measurement requirements for the proposed Gas and Ion Analyzer(GIA).The GIA is designed for in-situ mass spectrometry of neutral gases and low-energy ions,such as hydrogen,carbon,and oxygen,in the vicinity of 311P.Ion sampling techniques are essential for the GIA's Time-of-Flight(TOF)mass analysis capabilities.In this paper,we present an enhanced ion sampling technique through the development of an ion attraction model and an ion source model.The ion attraction model demonstrates that adjusting attraction grid voltage can enhance the detection efficiency of low-energy ions and mitigate the repulsive force of ions during sampling,which is influenced by the satellite's surface positive charging.The ion source model simulates the processes of gas ionization and ion multiplication.Simulation results indicate that the GIA can achieve a lower pressure limit below 10-13Pa and possess a dynamic range exceeding 10~9.These performances ensure the generation of ions with stable and consistent current,which is crucial for high-resolution and broad dynamic range mass spectrometer analysis.Preliminary testing experiments have verified GIA's capability to detect gas compositions such as H2O and N2.In-situ measurements near 311P using GIA are expected to significantly contribute to our understanding of asteroid activity mechanisms,the evolution of the atmospheric and ionized environments of main-belt comets,the interactions with solar wind,and the origin of Earth's water.
文摘An experimental technique for research on spherical divergent wave propagation in a solid has been developed, in which the source of generating spherical wave is a center initiating explosive charge designed in a mini-spherical shape with yield equivalent to 0.125?g and 0.486?g TNT and a set of circular electromagnetic particle velocity gages is used to record the particle velocity histories. By using the circular electromagnetic particle velocity gages, the signal outputs not only are unattenuated due to the geometrical divergence, but also represent the average of the measured dynamic states of the medium over a circle on the wavefront. The distinctive features of this technique are very useful for the study of spherical divergent wave propagation in a solid, especially in an inhomogeneous solid, and the corresponding material dynamics. Many experimental measurements were conducted in polymethylmethacrylate (PMMA) and granite by means of the technique, and the reproducibility of tests was shown to be good. The measurement technique of the circular electromagnetic particle velocity gages is also suitable to the case of cylindrical wave.
文摘目的应用定量CT(quantitative computed tomography,QCT)技术测量腰椎骨密度(bone mineral density,BMD),探讨体格测量、体成分分析指标与中老年男性腰椎BMD的相关性。方法本研究为横断面研究,选取2018年1月至2023年2月在河南省人民医院健康管理中心接受体格检查的1152名中老年男性体检者为研究对象,采集受试者年龄、身高、体重、血压、腰围、臀围、体脂肪质量与体肌肉质量数据,并计算体质量指数(body mass index,BMI)、体脂率(body fat percentage,BFP)与骨骼肌质量指数(skeletal muscle mass index,SMI)。同时使用QCT技术测量受试者腰椎BMD值,按照BMI进行分组,分为BMI正常组(18.5≤BMI<24 kg/m^(2))、超重及肥胖组(BMI为>24 kg/m^(2)),并在两组中分别按照骨量诊断标准进行讨论。采用单因素方差分析,Pearson相关性分析和偏相关分析体格测量、体成分分析指标与腰椎BMD的相关性。结果在BMI正常组中,骨质疏松组的年龄、收缩压、腰臀比、BFP显著高于骨量正常组,SMI显著低于骨量正常组与骨量减少组(P均<0.05);超重及肥胖组中,骨质疏松组的年龄、收缩压、腰围、腰臀比与BFP显著高于骨量正常组,SMI显著低于骨量正常组与骨量减少组(P均<0.05)。Pearson相关性分析结果显示,BMI正常组中腰椎BMD值与年龄、腰围、腰臀比、BFP呈显著负相关关系(r=-0.385,r=-0.122,r=-0.199,r=-0.168,P均<0.05),与SMI呈正相关(r=0.226,P<0.05);超重及肥胖组中腰椎BMD值与年龄、收缩压、腰围、腰臀比、BFP呈显著负相关关系(r=-0.379,r=-0.087,r=-0.101,r=-0.187,r=-0.199,P均<0.05),与SMI呈正相关(r=0.251,P<0.05)。在校正年龄因素后,偏相关分析分析结果显示,BMI正常组中腰椎BMD值与腰围、腰臀比、BFP呈显著负相关关系(r=-0.157,r=-0.212,r=-0.134,P均<0.05),与SMI呈正相关(r=0.167,P<0.05);超重及肥胖组中腰椎BMD值与腰围、腰臀比、BFP呈显著负相关关系(r=-0.120,r=-0.163,r=-0.126,P均<0.05),与SMI呈正相关(r=0.159,P<0.05)。结论腰围、腰臀比、BFP、SMI与中老年男性体检人群腰椎BMD值密切相关,对肥胖和骨质疏松症的预防与管理具有一定临床价值。
