空间光学遥感器遮光罩结构方案选择

利用有限元工程分析技术对空间光学遥感器的遮光罩结构方案进行了选择。应用MSC.Patran/Nastran软件对遮光罩进行了模态分析,应用TMG软件对遮光罩进行了热分析。根据模态分析和热分析的结果对遮光罩材料的铺层方式、遮光罩的结构形式和遮光罩的长度进行了优选。结果表明,[-45°/90°/45°/0°]s交叉对称铺层方式、一条轴向筋和1mm厚度、200mm长度的四棱台式遮光罩的结构方案是合理可行的。其结果为遮光罩的结构设计提供了必要的指导。     

壁面约束对裙带气泡动力学的影响

基于流体体积法(volume of fluid,VOF),数值模拟了装满黏性液体的圆柱形汽缸中的裙带气泡的浮升运动,研究了侧壁面约束对裙带气泡浮升动力学的影响.用雷诺数(Re)、韦伯数(We)、长宽比(χ)、裙带厚度(T/d)和裙带长度(L/d)等参数来表征不同约束比条件下(1.1≤Cr≤10)裙带气泡的运动和变形特性,分别在全局参考系和局部参考系下分析了壁面对气泡内外流场的影响.模拟结果显示,当Cr≥8时,裙带气泡的行为特性与在无界流域条件下的情况相当,可视作壁面无关的.当Cr8时,壁面对裙带气泡的浮升速度和形状演化有显著影响.随着壁面的靠近,裙带气泡受到的阻力增大,造成浮升速度下降.约束比降低使裙带厚度增厚而长度变短直至裙带消失,裙带气泡受挤压而被拉长并逐渐变为椭圆球帽形最后到子弹形.相反,约束比增大时,裙带气泡尾流效应增强,气泡边缘处流场产生明显的循环流动(涡环),促使裙带的形成.研究表明壁面会加剧裙带气泡产生破碎,印证了前人的推断.模拟结果与已有的经验公式吻合良好,分析了前人公式的适用性.     

微波消解-ICP-MS测定动物血清和组织器官中的微量银元素

银的应用在当代生物医学领域得到极大地推广,其生物安全性也受到密切关注,明确银离子在生物体内分布以及其安全阈值显得格外重要。因此,需要一种高灵敏度的分析方法来确定医学生物样品中银的含量。电感耦合等离子体质谱(ICP-MS)法对于金属离子检测具有很高的灵敏度,非常适用于医学生物样品中所含痕量银元素的检测,但具体方法的开发,包括样品前处理和检测过程,尚处于起步阶段。本研究建立了一套简便易行的微波消解处理机体血清和组织器官样品,通过ICP-MS法测定样品内微量银元素的检测方法。血清和肌肉、骨髓、骨骼组织,以及心脏、肝脏、脾脏、肾脏器官样品经5 mL硝酸-2 mL过氧化氢体系微波消解。消解程序采用2 000 W功率3步式温度梯度,样品最终消解完全,获得的数据重复性好,且耗费时间短,为大批量样品处理节省了时间。消解溶液经稀释定容,在优化仪器工作参数后,用ICP-MS对溶液中的107Ag进行测定,以钇(Y)为内标元素补偿基体效应和准确度漂移。测定结果显示,107Ag元素检出限为0.98 μg·kg-1,标准曲线相关系数为0.999 9,回收率为98%～107%,相对标准偏差(RSD)为2.0%～4.3%。用该法测定了动物血清和组织器官中的银元素含量,发现机体摄入银离子后,主要蓄积在肝脏。检测结果表明ICP-MS方法可以准确地测定机体的微量银元素,所建立的方法适用性强,可满足不同类型医学生物样品中微量银元素的测定,操作简便快捷,结果准确且灵敏度高,尤其适合于大批量生物样品的检测,为其他生物样品微量元素的检测提供了指导。     

Improvement of Nickel-Stanogermanide Contact Properties by Platinum Interlayer

We report an effective method to improve the formation of nickel stanogermanide(Ni Ge Sn) by the incorporation of a platinum(Pt) interlayer. After the Ni/Pt/Ge Sn samples are annealed we obtain uniform Ni Ge Sn thin films,which are characterized by means of sheet resistance, atomic force microscopy, scanning electron microscopy,cross-section transmission electron microscopy, and energy dispersive x-ray spectroscopy. These results show that the presence of Pt increases the smoothness and uniform morphology of Ni Ge Sn films.     

Microwave interrogation cavity for the rubidium space cold atom clock

The performance of space cold atom clocks(SCACs) should be improved thanks to the microgravity environment in space.The microwave interrogation cavity is a key element in a SCAC.In this paper,we develop a microwave interrogation cavity especially for the rubidium SCAC.The interrogation cavity has two microwave interaction zones with a single feedin source,which is located at the center of the cavity for symmetric coupling excitation and to ensure that the two interaction zones are in phase.The interrogation cavity has a measured resonance frequency of 6.835056471 GHz with a loaded quality factor of nearly 4200,which shows good agreement with simulation results.We measure the Rabi frequency of the clock transition of the rubidium atom in each microwave interaction zone,and subsequently demonstrate that the distributions of the magnetic field in the two interaction zones are the same and meet all requirements of the rubidium SCAC.     

活性氧化锰的制备及表征

采用不同方法制备了五种活性氧化锰，并对它们进行了苯六酚氧化实验、锰氧分析、粉末XRD分析和差热-热重分析，测定了比表面积，指出组成与结构以及比表面积是影响活性氧化锰氧化活性的主要因素，为活性氧化锰的选择与使用提供了依据。     

Molecular beam epitaxy growth of monolayer hexagonal MnTe2 on Si(111) substrate

Monolayer MnTe₂ stabilized as 1T structure has been theoretically predicted to be a two-dimensional (2D) ferromagnetic metal and can be tuned via strain engineering. There is no naturally van der Waals (vdW) layered MnTe₂ bulk, leaving mechanical exfoliation impossible to prepare monolayer MnTe₂. Herein, by means of molecular beam epitaxy (MBE), we successfully prepared monolayer hexagonal MnTe₂ on Si(111) under Te rich condition. Sharp reflection high-energy electron diffraction (RHEED) and low-energy electron diffraction (LEED) patterns suggest the monolayer is atomically flat without surface reconstruction. The valence state of Mn⁴⁺ and the atom ratio of ([Te]:[Mn]) further confirm the MnTe₂ compound. Scanning tunneling spectroscopy (STS) shows the hexagonal MnTe₂ monolayer is a semiconductor with a large bandgap of ~2.78 eV. The valence-band maximum (VBM) locates at the Γ point, as illustrated by angle-resolved photoemission spectroscopy (ARPES), below which three hole-type bands with parabolic dispersion can be identified. The successful synthesis of monolayer MnTe₂ film provides a new platform to investigate the 2D magnetism.     

由圆柱和正方柱导体组成的同轴线的新研究

本文对由圆柱和正方柱导体组成的同轴线作了进一步研究.并将其中的某些方法推广应用于研究由圆柱和正N棱柱导体组成的同轴线.我们在文献[1]的启示和指导下,利用中值等位线得到了内圆外方同轴线特性阻抗的严格计算公式.同时修正了文献[1]点匹配值.我们还通过假想一个导体存在于第一次保角变换后的图形之中,再作一次变换,改进了文献[1]的阻抗上下限.     

Integrated,reliable laser system for an 87Rb cold atom fountain clock

We designed, assembled, and tested a reliable laser system for ⁸⁷Rb cold atom fountain clocks. The laser system is divided into four modules according to function, which are convenient for installing, adjusting, maintaining, and replacing of the modules. In each functional module, all optical components are fixed on a baseplate with glue and screws, ensuring the system's structural stability. Mechanical stability was verified in a 6.11g RMS randomvibration test, where the change in output power before and after vibration was less than 5%. Thermal stability was realized by optimizing of the structure and appropriate selection of component materials of the modules through thermal simulation. In the laser splitting and output module, the change in laser power was less than 20% for each fiber in thermal cycles from 5 ℃ to 43 ℃. Finally, the functionality of the laser system was verified for a rubidium fountain clock.     

钛酸盐ATiO3钙钛矿的铁电和反铁畸变

钛酸盐钙钛矿氧化物体系的研究对理解具有铁电极化的功能材料具有非常重要的科学意义.本文对ATiO3(A=Ca,Sr,Ba,Pb,Cd)体系的低温相、结构相变、及其对应的位移模式进行综述.我们着重比较了该体系存在的两类不稳定声子模式,即铁电极化模式(Ferroelectric,FE)和反铁畸变模式(Antiferrodistortive,AFD),在不同体系中所起到的作用.我们举例阐述了晶格失配应变、人工构造超晶格和化学掺杂等方法对这两种模式的调控思路.最后我们给出本文的总结讨论及研究展望.