scholarly journals Survivability of Anhydrobiotic Cyanobacteria in Salty Ice: Implications for the Habitability of Icy Worlds

Life ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 86 ◽  
Author(s):  
Barbara Cosciotti ◽  
Amedeo Balbi ◽  
Alessandra Ceccarelli ◽  
Claudia Fagliarone ◽  
Elisabetta Mattei ◽  
...  
Keyword(s):  
Low Temperature ◽  
Eutectic Temperature ◽  
Life Forms ◽  
Dry Valleys ◽  
Nacl Solution ◽  
Microbial Life ◽  
Icy Moons ◽  
Liquid Solutions ◽  
Eutectic Concentration ◽  
Experimental Runs

Two anhydrobiotic strains of the cyanobacterium Chroococcidiopsis, namely CCMEE 029 and CCMEE 171, isolated from the Negev Desert in Israel and from the Dry Valleys in Antarctica, were exposed to salty-ice simulations. The aim of the experiment was to investigate the cyanobacterial capability to survive under sub-freezing temperatures in samples simulating the environment of icy worlds. The two strains were mixed with liquid solutions having sub-eutectic concentration of Na2SO4, MgSO4 and NaCl, then frozen down to different final temperatures (258 K, 233 K and 203 K) in various experimental runs. Both strains survived the exposure to 258 K in NaCl solution, probably as they migrated in the liquid veins between ice grain boundaries. However, they also survived at 258 K in Na2SO4 and MgSO4-salty-ice samples—that is, a temperature well below the eutectic temperature of the solutions, where liquid veins should not exist anymore. Moreover, both strains survived the exposure at 233 K in each salty-ice sample, with CCMEE 171 showing an enhanced survivability, whereas there were no survivors at 203 K. The survival limit at low temperature was further extended when both strains were exposed to 193 K as air-dried cells. The results suggest that vitrification might be a strategy for microbial life forms to survive in potentially habitable icy moons, for example in Europa’s icy crust. By entering a dried, frozen state, they could be transported from niches, which became non-habitable to new habitable ones, and possibly return to metabolic activity.

Effect of Equal Channel Angular Pressing and Annealing on Corrosion Resistance of Al-Cu Alloy

2013 ◽  
Vol 803 ◽  
pp. 226-229
Author(s):  
Da Ran Fang ◽  
Chun Liu ◽  
Feng Fang Liu
Keyword(s):  
Corrosion Resistance ◽  
Low Temperature ◽  
Equal Channel Angular Pressing ◽  
Annealing Treatment ◽  
Coarse Grained ◽  
Nacl Solution ◽  
Angular Pressing ◽  
Cu Alloy ◽  
Low Temperature Annealing ◽  
Ultrafine Grained

Al-3.9wt.%Cu alloy was subjected to equal channel angular pressing (ECAP) and subsequent low temperature annealing treatment, and the corrosion resistance of the samples was investigated by potentiodynamic polarization measurements in 3.5% NaCl solution. The results show that the corrosion rate of the ultrafine-grained alloy increases, in comparison with the coarse-grained alloy. Meanwhile, it is noted that the corrosion resistance of the alloy subjected to ECAP can be improved by relief annealing.

Origin of Clusters: IV. Low Temperature Fast-Atom Bombardment Cluster Patterns Point to the Possible Existence of NaCl Crystalline Hydrates Incorporating Heavy Water

2002 ◽  
Vol 8 (2) ◽  
pp. 157-161 ◽  
Author(s):  
Marina V. Kosevich ◽  
Oleg A. Boryak ◽  
Vadim S. Shelkovsky
Keyword(s):  
Low Temperature ◽  
Heavy Water ◽  
Fast Atom Bombardment ◽  
Reference Data ◽  
Mass Spectrometry Data ◽  
Crystalline Hydrate ◽  
Nacl Solution ◽  
Characteristic Distribution ◽  
Cluster Pattern ◽  
Crystalline Hydrates

Low temperature fast-atom bombardment study of frozen D2O–NaCl solutions gave results similar to those obtained earlier for the H2O–NaCl system. Thus, sets of clusters (D2O) n•D+, (D2O) n•Na+, (D2O) n•NaCl•Na+, (NaCl) m•Na+ with a characteristic distribution depending on the composition of the sample and phase transitions on its thawing were recorded. A typical cluster pattern, attributed in the case of the H2O–NaCl system to a phase of a crystalline hydrate NaCl•2H2O, was observed for the D2O–NaCl system as well. At the same time, recently available reference data on the solubility of NaCl do not contain a specification for the formation of a crystalline hydrate on cooling of NaCl solution in D2O. Considering the present mass spectrometry data, the possibility of incorporation of heavy water into NaCl crystalline hydrates is discussed.

Possible evidence for panspermia: the labelled release experiment

2007 ◽  
Vol 6 (2) ◽  
pp. 95-108 ◽  
Author(s):  
Gilbert V. Levin
Keyword(s):  
Active Agent ◽  
Life Forms ◽  
Current Data ◽  
Release Experiment ◽  
Microbial Life ◽  
Martian Soil ◽  
Life On Mars ◽  
Biological Interpretation ◽  
Life Question ◽  
Chiral Specificity

Abstract30 years after the Viking Mission landed on Mars (20 July 1976) to search for life, despite the positive findings of the Labelled Release (LR) experiment, the issue remains unresolved. The controversial history, following the immediate dismissal of the LR’s evidence for microbial activity in the Martian soil, and the later claim to its having found living microorganisms are reviewed. The bearing of post-Viking-to-current data on the issue is discussed in the context of the scientific community’s growing interest in the long-dismissed possibility of microbial life on Mars. Objections raised over the years to the biological interpretation of the Mars LR, those currently maintained, and their rebuttals are reviewed. A case is presented that enough evidence now exists for an objective review by astrobiologists to resolve this key issue, a review, surprisingly, not yet held. The results could greatly influence NASA’s currently shifting plans for Mars exploration. A variation of the LR experiment to test for chiral specificity in the metabolism of substrates by the active agent found in the Martian soil, and thus having the capability of obtaining an unambiguous answer to the life question, is proposed. Confirmation of life on Mars by this experiment can also determine whether Martian and Earth life forms share a common heritage. Together with mounting evidence for the viable transfer of microorganisms between the two planets, this would be evidence for panspermia, and establish the presence of a common biosphere in which the two planets participate. Should Martian microorganisms show a different chiral specificity than that of Earth life then this would indicate separate origins of the two neighbouring life forms, thereby strongly implying that life occurs widely throughout the cosmos. Any one of these possible outcomes would be a paradigm-breaking event.

Improved calcium sulfate recovery from a reverse osmosis retentate using eutectic freeze crystallization

2013 ◽  
Vol 67 (1) ◽  
pp. 139-146 ◽  
Author(s):  
D. G. Randall ◽  
R. Mohamed ◽  
J. Nathoo ◽  
H. Rossenrode ◽  
A. E. Lewis
Keyword(s):  
Low Temperature ◽  
Reverse Osmosis ◽  
Calcium Sulfate ◽  
Crystallization Process ◽  
Eutectic Temperature ◽  
Water Recovery ◽  
Recovery Rates ◽  
Low Temperature Crystallization ◽  
Operating Temperatures ◽  
Temperature Crystallization

A novel low temperature crystallization process called eutectic freeze crystallization (EFC) can produce both salt(s) and ice from a reverse osmosis (RO) stream by operating at the eutectic temperature of a solution. The EFC reject stream, which is de-supersaturated with respect to the scaling component, can subsequently be recycled back to the RO process for increased water recovery. This paper looks at the feasibility of using EFC to remove calcium sulfate from an RO retentate stream and compares the results to recovery rates at 0 and 20 °C. The results showed that there was a greater yield of calcium sulfate obtained at 0 °C as compared with 20 °C. Operation under eutectic conditions, with only a 20% ice recovery, resulted in an even greater yield of calcium sulfate (48%) when compared with yields obtained at operating temperatures of 0 and 20 °C (15% at 0 °C and 13% at 20 °C). The theoretical calcium recoveries were found to be 75 and 70% at 0 and 20 °C respectively which was higher than the experimentally determined values. The EFC process has the added advantage of producing water along with a salt.

scholarly journals Salt Priming Protects Photosynthetic Electron Transport against Low-Temperature-Induced Damage in Wheat

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 62 ◽  
Author(s):  
Hui Li ◽  
Huawei Li ◽  
Yanjie Lv ◽  
Yongjun Wang ◽  
Zongshuai Wang ◽  
...  
Keyword(s):  
Electron Transport ◽  
Low Temperature ◽  
Reaction Center ◽  
Early Stage ◽  
Photochemical Efficiency ◽  
Photosynthetic Electron Transport ◽  
Nacl Solution ◽  
Wheat Seedlings ◽  
Germinating Seeds ◽  
Salt Priming

Low temperature limits the photochemical efficiency of photosystems in wheat plants. To test the effect of salt priming on the photosynthetic electron transport in wheat under low temperature, the germinating seeds of a winter wheat cv. Jimai44 were primed with varying concentrations of NaCl solutions (0, 10, 30, and 50 mM NaCl, indicated by S0, S10, S30, and S50, respectively) for 6 d, and after 11 d of recovery, the seedlings were subsequently exposed to 24-h low-temperature stress (2 °C). Under low temperature, the S30 plants possessed the highest absorption flux per reaction center and higher density of reaction center per cross-section among the treatments. In addition, S30 plants had higher trapped energy flux for reducing QA and fraction of QA-reducing reaction centers and non-QB reducing center than the non-primed plants under low temperature, indicating that S30 plants could maintain the energy balance of photosystems and a relatively higher maximum quantum efficiency of photosystem II under low temperature. In addition, the low temperature-induced MDA accumulation and cell death were alleviated by salt priming in S30 plants. It was suggested that salt priming with an optimal concentration of NaCl solution (30 mM) during seed germination enhanced the photochemical efficiency of photosystems in wheat seedlings, which could be a potential approach to improve cold tolerance in wheat at an early stage.

scholarly journals The Orestes Melt Zone, McMurdo Dry Valleys, Antarctica: Spatially Distributed Melting Regimes in a Contact Melt Zone, with Implications for the Formation of Rapakivi and Albite Granites

2019 ◽  
Vol 60 (11) ◽  
pp. 2077-2100
Author(s):  
R M Currier ◽  
T P Flood
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Late Stage ◽  
Eutectic Composition ◽  
Thermal Modeling ◽  
Mcmurdo Dry Valleys ◽  
Contact Temperature ◽  
Dry Valleys ◽  
Spatially Distributed ◽  
Water Saturated

Abstract The Orestes Melt Zone (OMZ) is a massive contact melt zone (∼20 m thick by several kilometers long), located in the McMurdo Dry Valleys of Antarctica. The OMZ formed at shallow crustal depths by melting of the A-type Orestes Granite owing to intrusion of the underlying, doleritic Basement Sill. The OMZ can be divided broadly into two melting facies. The upper melting facies is distal from the contact and formed by melting at low temperature and water-saturated, or near water-saturated, conditions. The lower melting facies is proximal to the contact and formed by melting at high temperature and water-undersaturated conditions. Separate melting reactions occurred in both of the melting facies, resulting in distinct textures and melt compositions. Melting in the distal facies generated melts with compositions that plot near a predicted eutectic composition. Melting in the proximal facies was accomplished in part by replacement reactions in restitic feldspars. These reactions resulted in the development of plagioclase mantles on both restitic plagioclase and K-feldspar, and melt compositions that diverged from predicted minimum melt along an unexpected path, towards enrichment in orthoclase component. Thermal modeling indicates that this melt zone was active for a minimum of ∼150 years, with a contact temperature of ∼900 °C. Upon cooling, recrystallization generated ocellar textures around restitic quartz, as well as faceted albite as a late-stage product. Observations of the OMZ, combined with thermal modeling, provide new insights into the origin of rapakivi and albite granites. This study has implications for the origin of these two associated granite types in other geological settings.

Effect of Equal Channel Angular Pressing and Annealing on Corrosion Resistance of Cu-Zn Alloy

2013 ◽  
Vol 706-708 ◽  
pp. 78-81 ◽  
Author(s):  
D.R. Fang ◽  
F.F. Liu ◽  
Chun Liu
Keyword(s):  
Corrosion Resistance ◽  
Low Temperature ◽  
Equal Channel Angular Pressing ◽  
Annealing Treatment ◽  
Coarse Grained ◽  
Nacl Solution ◽  
Angular Pressing ◽  
Low Temperature Annealing ◽  
Ultrafine Grained ◽  
Zn Alloy

Cu-32wt.%Zn alloy was subjected to equal channel angular pressing (ECAP) and subsequent low temperature annealing treatment, and the corrosion resistance of the samples was investigated by potentiodynamic polarization measurements in 3.5% NaCl solution. The results show that the corrosion rate of the ultrafine-grained alloy decreases, in comparison with the coarse-grained alloy. Meanwhile, it is noted that the corrosion resistance of the sample subjected to ECAP can be further improved by relief annealing.

scholarly journals Biologically–induced elemental variations in Antarctic sandstones: a potential test for Martian micro-organisms

2004 ◽  
Vol 3 (2) ◽  
pp. 97-106 ◽  
Author(s):  
Rebecca L. Blackhurst ◽  
Kym Jarvis ◽  
Monica M. Grady
Keyword(s):  
Host Rock ◽  
Inductively Coupled Plasma ◽  
Pore Space ◽  
Atomic Emission ◽  
Life Forms ◽  
Dry Valleys ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Trace Element Study ◽  
Micro Organisms

Lichen-dominated cryptoendolithic communities from the Dry Valleys of Antarctica have been the subject of much research over recent years owing to their potential as analogues of Martian life forms. Their ability to mobilize iron compounds and organize themselves into distinct coloured biotic zones suggests that they may alter the chemistry of their host rock. By conducting a major, minor and trace element study utilizing inductively coupled plasma atomic emission spectroscopy (ICP-AES) and mass spectrometry (ICP-MS) techniques, we have been investigating the relationship between the microbes and the chemistry of the sandstones. Different layers within a suite of sandstones collected from six localities in the Dry Valleys have been analysed to establish if or how the microbes influence or directly affect the chemical composition of the rocks. Background petrographic studies have shown significant differences in mineralogical maturity between rocks colonized by the communities and those that are not, and the chemistry results have shown significant elemental disparity between colonized and uncolonized rocks. By obtaining accurate percentages of the minerals present in each sample the differences in elemental concentrations could be construed to be caused by the differences in mineralogy between samples. The nature and extent of the concentration differences has led to the conclusion that either the cryptoendolith communities are able to alter their host rock by the solubilization and mobilization of elements that are then subsequently removed or that the organisms are simple opportunists that can only successfully colonize rocks that provide the ideal substrate, being mineralogically mature with ample pore space and less concentrated in the elements tested for.

ESR Linewidths of Vanadyl β-Diketonate Complexes in Liquid Solutions

1975 ◽  
Vol 53 (15) ◽  
pp. 1492-1498
Author(s):  
T. E. Eagles ◽  
R. E. D. McClung
Keyword(s):  
Electron Spin Resonance ◽  
Low Temperature ◽  
Temperature Region ◽  
Low Temperatures ◽  
Esr Spectra ◽  
Simple Description ◽  
Solvent Viscosity ◽  
Spin Resonance ◽  
Liquid Solutions ◽  
Rotational Interaction

The electron spin resonance (ESR) spectra of a series of vanadyl β-diketonate complexes in dilute solutions in several inert solvents have been investigated. The widths of the lines in these spectra have been interpreted in terms of the Kivelson linewidth theory. Significant discrepancies between the experimental linewidths and those predicted by the theory were found at low temperatures and high solvent viscosities. It is concluded that the Stokes–Einstein relationship, which relates the reorientational correlation time to the solvent viscosity, is not valid in the low temperature region and that the simple description of spin relaxation by the spin–rotational interaction given by Atkins and Kivelson is inadequate.

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