Experimentally tracing the key steps in the origin of life: The aromatic world

Life is generally believed to emerge on Earth, to be at least functionally similar to life as we know it today, and to be much simpler than modern life. Although minimal life is notoriously difficult to define, a molecular system can be considered alive if it turns resources into building blocks, replicates, and evolves. Primitive life may have consisted of a compartmentalized genetic system coupled with an energy-harvesting mechanism. How prebiotic building blocks self-assemble and transform themselves into a minimal living system can be broken into two questions: (1) How can prebiotic building blocks form containers, metabolic networks, and informational polymers? (2) How can these three components cooperatively organize to form a protocell that satisfies the minimal requirements for a living system? The functional integration of these components is a difficult puzzle that requires cooperation among all the aspects of protocell assembly: starting material, reaction mechanisms, thermodynamics, and the integration of the inheritance, metabolism, and container functionalities. Protocells may have been self-assembled from components different from those used in modern biochemistry. We propose that assemblies based on aromatic hydrocarbons may have been the most abundant flexible and stable organic materials on the primitive Earth and discuss their possible integration into a minimal life form. In this paper we attempt to combine current knowledge of the composition of prebiotic organic material of extraterrestrial and terrestrial origin, and put these in the context of possible prebiotic scenarios. We also describe laboratory experiments that might help clarify the transition from nonliving to living matter using aromatic material. This paper presents an interdisciplinary approach to interface state of the art knowledge in astrochemistry, prebiotic chemistry, and artificial life research.     

SOLID3: a multiplex antibody microarray-based optical sensor instrument for in situ life detection in planetary exploration

The search for unequivocal signs of life on other planetary bodies is one of the major challenges for astrobiology. The failure to detect organic molecules on the surface of Mars by measuring volatile compounds after sample heating, together with the new knowledge of martian soil chemistry, has prompted the astrobiological community to develop new methods and technologies. Based on protein microarray technology, we have designed and built a series of instruments called SOLID (for "Signs Of LIfe Detector") for automatic in situ detection and identification of substances or analytes from liquid and solid samples (soil, sediments, or powder). Here, we present the SOLID3 instrument, which is able to perform both sandwich and competitive immunoassays and consists of two separate functional units: a Sample Preparation Unit (SPU) for 10 different extractions by ultrasonication and a Sample Analysis Unit (SAU) for fluorescent immunoassays. The SAU consists of five different flow cells, with an antibody microarray in each one (2000 spots). It is also equipped with an exclusive optical package and a charge-coupled device (CCD) for fluorescent detection. We demonstrated the performance of SOLID3 in the detection of a broad range of molecular-sized compounds, which range from peptides and proteins to whole cells and spores, with sensitivities at 1-2?ppb (ng?mL?1) for biomolecules and 10? to 103 spores per milliliter. We report its application in the detection of acidophilic microorganisms in the Río Tinto Mars analogue and report the absence of substantial negative effects on the immunoassay in the presence of 50?mM perchlorate (20 times higher than that found at the Phoenix landing site). Our SOLID instrument concept is an excellent option with which to detect biomolecules because it avoids the high-temperature treatments that may destroy organic matter in the presence of martian oxidants.     

A two-tiered approach to assessing the habitability of exoplanets

In the next few years, the number of catalogued exoplanets will be counted in the thousands. This will vastly expand the number of potentially habitable worlds and lead to a systematic assessment of their astrobiological potential. Here, we suggest a two-tiered classification scheme of exoplanet habitability. The first tier consists of an Earth Similarity Index (ESI), which allows worlds to be screened with regard to their similarity to Earth, the only known inhabited planet at this time. The ESI is based on data available or potentially available for most exoplanets such as mass, radius, and temperature. For the second tier of the classification scheme we propose a Planetary Habitability Index (PHI) based on the presence of a stable substrate, available energy, appropriate chemistry, and the potential for holding a liquid solvent. The PHI has been designed to minimize the biased search for life as we know it and to take into account life that might exist under more exotic conditions. As such, the PHI requires more detailed knowledge than is available for any exoplanet at this time. However, future missions such as the Terrestrial Planet Finder will collect this information and advance the PHI. Both indices are formulated in a way that enables their values to be updated as technology and our knowledge about habitable planets, moons, and life advances. Applying the proposed metrics to bodies within our Solar System for comparison reveals two planets in the Gliese 581 system, GJ 581 c and d, with an ESI comparable to that of Mars and a PHI between that of Europa and Enceladus.     

微型战术陀螺——低成本陀螺的替代物

固态光学陀螺的优势正受到一种新型的旋转质量装置的挑战，这种较低成本的器件具有良好的低噪声漂移及高可靠性的性能。微型战术陀螺是一种性能优良的双轴陀螺，它采用先进的旋转质量装置的技术，以建立新的低成本标准。它具有不不带挠性支撑系统的调谐转子陀螺的低噪声性能。综合了球形动压气浮轴承及三轴永磁直流电机和力矩器的优点，设计成动态范围大于１０＾７的微型双轴陀螺。本文介绍了该设计及验证这种低成本下一代速率陀螺性     

在SA条件下利用GPS的轨道确定和点定位

GPS精度控制(SA)措施降低了GPS标准定位业务(SPS)非差分用户的定位精度。常说的SPS可达精度在正常条件下为100米(2DRMS)。在缺乏更多具体条件下,许多未来的SPS用户在他们的规划中采用了100米这一精度值,但多数情况下,是夸大了实际定位误差。在本文中,我们针对轨道用户星的点定位和动力学轨道确定来研究SA带来的误差。要使SA带来的误差减至最小,非差分用户有几种选择:扩大接收视场;观测尽可能多的GPS卫星;在时间上平滑误差;选用独立计算的GPS精密轨道星历(如NASA和美国测绘局计算的),而不采用广播星历。仿真计算表明,3维点位误差可保持在30米,并且在几小时内能平滑到3米。     

玻璃碳断裂性能的一些研究

本文简要介绍用“声共振法”测材料的杨氏模量,用“控制裂纹法”测材料的断裂韧性以及材料的极限应变能释放率的计算。对三种玻璃碳的室温-1023°K的杨氏模量和断裂韧性进行了测定,用电子扫描显微镜对玻璃碳的断裂、氧化和加工表面进行研究观察,分析了玻璃碳的极限应变能释放率并与多晶石墨及碳-碳复合材料进行比较。     

三轴激光陀螺惯性敏感组件

用整体式的三轴ＰＩＸＹＺ代替三个单轴激光陀螺构成的惯性导航系统有很多优点。与传统的结构相比，ＰＩＸＹＺ惯性灵敏组件存在固有的对称性和平衡性。数据处理过程被简化，高频振动补偿更简单，圆锥运动更低，需使用的计算机频率较低，挠曲的影响也可以被修正过来。     

在特定条件下的激波风洞中的压力测量

1.引言激波风洞实质上是由与轴线垂直安装的气密膜片分两部分的刚性圆筒组成,膜片两边各加以不同的压力。当膜片被爆破时,由于激波传入低压部分(被驱动段)稀疏波传入高压部分(驱动段),而使压力渐趋相等。如果管子有恒定的截面。激波强度不随距离而衰减。在激波后面的一定区域内,压力和质点速度也不变。正是由于激波风洞能提供可控制的激波和气流,使它在很多的研究工作中,成为很宝贵