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191.
Parro V de Diego-Castilla G Moreno-Paz M Blanco Y Cruz-Gil P Rodríguez-Manfredi JA Fernández-Remolar D Gómez F Gómez MJ Rivas LA Demergasso C Echeverría A Urtuvia VN Ruiz-Bermejo M García-Villadangos M Postigo M Sánchez-Román M Chong-Díaz G Gómez-Elvira J 《Astrobiology》2011,11(10):969-996
The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5?m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2?m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5?g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260?g kg(-1)) and perchlorate (41.13?μg g(-1) maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14?μg g(-1)) or formate (76.06?μg g(-1)) as electron donors, and sulfate (15875?μg g(-1)), nitrate (13490?μg g(-1)), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars. 相似文献
192.
de Diego-Castilla G Cruz-Gil P Mateo-Martí E Fernández-Calvo P Rivas LA Parro V 《Astrobiology》2011,11(8):759-773
Antibody microarrays are becoming frequently used tools for analytical purposes. A key factor for optimal performance is the stability of the immobilized (capturing) antibodies as well as those that have been fluorescently labeled to achieve the immunological test (tracers). This is especially critical for long-distance transport, field testing, or planetary exploration. A number of different environmental stresses may affect the antibody integrity, such as dryness, sudden temperature shift cycles, or, as in the case of space science, exposure to large quantities of the highly penetrating gamma radiation. Here, we report on the effect of certain stabilizing solutions for long-term storage of printed antibody microarrays under different conditions. We tested the effect of gamma radiation on printed and freeze- or vacuum-dried fluorescent antibodies at working concentrations (tracer antibodies), as well as the effect of multiple cycles of sudden and prolonged temperature shifts on the stability of fluorescently labeled tracer antibody cocktails. Our results show that (i) antibody microarrays are stable at room temperature when printed on stabilizing spotting solutions for at least 6 months, (ii) lyophilized and vacuum-dried fluorescently labeled tracer antibodies are stable for more than 9 months of sudden temperature shift cycles (-20°C to 25°C and 50°C), and (iii) both printed and freeze- or vacuum-dried fluorescent tracer antibodies are stable after several-fold excess of the dose of gamma radiation expected during a mission to Mars. Although different antibodies may exhibit different susceptibilities, we conclude that, in general, antibodies are suitable for use in planetary exploration purposes if they are properly treated and stored with the use of stabilizing substances. 相似文献
193.
Paulino-Lima IG Janot-Pacheco E Galante D Cockell C Olsson-Francis K Brucato JR Baratta GA Strazzulla G Merrigan T McCullough R Mason N Lage C 《Astrobiology》2011,11(9):875-882
In this experimental study, cells of the radiation-resistant bacterium Deinococcus radiodurans were exposed to several different sources of radiation chosen to replicate the charged particles found in the solar wind. Naked cells or cells mixed with dust grains (basalt or sandstone) differing in elemental composition were exposed to electrons, protons, and ions to determine the probability of cell survival after irradiation. Doses necessary to reduce the viability of cell population to 10% (LD(10)) were determined under different experimental conditions. The results of this study indicate that low-energy particle radiation (2-4?keV), typically present in the slow component of the solar wind, had no effect on dehydrated cells, even if exposed at fluences only reached in more than 1000 years at Sun-Earth distance (1 AU). Higher-energy ions (200?keV) found in solar flares would inactivate 90% of exposed cells after several events in less than 1 year at 1 AU. When mixed with dust grains, LD(10) increases about 10-fold. These results show that, compared to the highly deleterious effects of UV radiation, solar wind charged particles are relatively benign, and organisms protected under grains from UV radiation would also be protected from the charged particles considered in this study. 相似文献
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G. S. Booth 《航空制造技术》2004,(Z1):1-4
Developments and opportunities for manufacturing with lasers are considered in three broad themes. Process enhancements, in particular hybrid-laser arc welding and twin spot laser welding are described. Two examples of novel manufacturing processes (laser joining of aluminium to steel and laser direct metal deposition) are considered. Finally, a new laser source (Yb: YAG fibre laser) is introduced as an additional competing processing capability. 相似文献
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本文重点论述了导航和瞄准用的三个重要航空电子设备--地形跟随/地形回避雷达、雷达高度表和前视红外的接收机的飞行试验和评定,并扼要介绍了每个设备所使用的试验程序以及评定的结果,文中提出的建议,可用作研究未来夜间攻击机航空电子设备飞行试验的经验。 相似文献
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1 引言 大家公认,尽管使用电源电子电路有许多优点,如高频、零声频噪声、响应速度等等,但双重稳定性,即这种形式的系统固有的工作转换模式,可能引起不必要的谐波成分。在电源频率范围以内,典型的是高达40倍的电源基频,这样的问题在文献[1,2,3]中充分做了说明,例如各种减轻手段、对策、模拟技术以及性能的可接受程度[4,5]。 相似文献