Genesis and preservation of a uranium-rich paleozoic epithermal system with a surface expression (Northern Flinders Ranges, South Australia): radiogenic heat driving regional hydrothermal circulation over geological timescales

The surface expressions of hydrothermal systems are prime targets for astrobiological exploration, and fossil systems on Earth provide an analogue to guide this endeavor. The Paleozoic Mt. Gee-Mt. Painter system (MGPS) in the Northern Flinders Ranges of South Australia is exceptionally well preserved and displays both a subsurface quartz sinter (boiling horizon) and remnants of aerial sinter pools that lie in near-original position. The energy source for the MGPS is not related to volcanism but to radiogenic heat produced by U-Th-K-rich host rocks. This radiogenic heat source drove hydrothermal circulation over a long period of time (hundreds of millions of years, from Permian to present), with peaks in hydrothermal activity during periods of uplift and high water supply. This process is reflected by ongoing hot spring activity along a nearby fault. The exceptional preservation of the MGPS resulted from the lack of proximal volcanism, coupled with tectonics driven by an oscillating far-field stress that resulted in episodic basement uplift. Hydrothermal activity caused the remobilization of U and rare earth elements (REE) in host rocks into (sub)economic concentrations. Radiogenic-heat-driven systems are attractive analogues for environments that can sustain life over geological times; the MGPS preserves evidence of episodic fluid flow for the past ～300 million years. During periods of reduced hydrothermal activity (e.g., limited water supply, quiet tectonics), radiolytic H(2) production has the potential to support an ecosystem indefinitely. Remote exploration for deposits similar to those at the MGPS systems can be achieved by combining hyperspectral and gamma-ray spectroscopy.     

Characterization of Bacilli isolated from the confined environments of the Antarctic Concordia station and the International Space Station

Bacillus and related genera comprise opportunist and pathogen species that can threaten the health of a crew in confined stations required for long-term missions. In this study, 43 Bacilli from confined environments, that is, the Antarctic Concordia station and the International Space Station, were characterized in terms of virulence and plasmid exchange potentials. No specific virulence feature, such as the production of toxins or unusual antibiotic resistance, was detected. Most of the strains exhibited small or large plasmids, or both, some of which were related to the replicons of the Bacillus anthracis pXO1 and pXO2 virulence elements. One conjugative element, the capacity to mobilize and retromobilize small plasmids, was detected in a Bacillus cereus sensu lato isolate. Six out of 25 tested strains acquired foreign DNA by conjugation. Extremophilic bacteria were identified and exhibited the ability to grow at high pH and salt concentrations or at low temperatures. Finally, the clonal dispersion of an opportunist isolate was demonstrated in the Concordia station. Taken together, these results suggest that the virulence potential of the Bacillus isolates in confined environments tends to be low but genetic transfers could contribute to its capacity to spread.     

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.     

纤维陶瓷复合材料强度和热稳定性的提高

最近研制了一代新型的刚性好重量轻的先进纤维陶瓷复合材料。这类材料在力学性能和热稳定性方面有很大提高。它的抗弯强度是当前能得到的氧化硅纤维绝热材料的2-3倍,而密度减小10％。该材料短时间的重复使用温度高于2600°F,而连续使用温度为2600°F。     

陆军战术无人侦察机（下）——苏联／俄罗斯战术无人侦察机

在当今世界，无人机以其独特的优势日益受到各国军方的青睐。无人机的研制，运用和发展也可谓方兴未艾。但对世人来讲，世界航空大国俄罗斯的无人机长期以来却一直是个谜……早在20世纪50年代初，随着喷气式发动机的诞生，苏联开始研制中远程巡航导弹和洲际弹道导弹以及军用无人机。军用无人机拥有有人驾驶飞机不可替代的许多优点：结构设汁简单、起降简便等，从而在军用航空武器中占据了特殊的地位。其无人机的发展大致可分为三个阶段。[编者按]     

设备分公司价值工程

价值工程是认识产品的基本功能并创造出成本较低的可靠的替代方案的一项技术.在产品研制阶段,通过价值工程来改进利润增长是靠避免不必要的费用来实现的.价值工程的目的是改进产品价值和利润这两个方面.按基本功能设计并消除次要功能的做法既能简化设计,又能避免不必要的费用.结果是产品价值比较好,其所得节余表明利润增长.买主总在寻求较好的产品价值和较少的费用,雷锡思公司则竭力设法满     

待发式运载工具推进方式的评价

未来的地球—轨道运载工具应能在作出决定后的几小时、甚至几分钟内发射.这种运载工具的研究工作已经开始.在第一阶段的研究中,设计出了11种能将2.27t载荷送入极轨道的运载工具,并验证了设计参数的变化(增加轨道机动飞行动作、增加载荷重量等).根据第一阶段研究结果,第二阶段的设计工作选择了两种方案,即垂直起飞的两级系统和水平起飞的两级系统.给出了几种推进方式的评估结果,包括起飞时的推重比效果、水平起飞的双燃料推进方案和使用氟的效果等.