Microbial activity in debris-rich basal ice; adaption to sub-zero, saline conditions

NASA Astrophysics Data System (ADS)

Montross, S. N.; Skidmore, M. L.; Christner, B. C.; Griggs, R.; Tison, J.; Sowers, T. A.

2011-12-01

Polycrystalline ice in glaciers and ice sheets has a high preservation potential for biological material and chemical compounds that can be used to document the presence of active microbial metabolism at sub-zero temperatures. The concentration and isotopic composition of gases, in conjunction with other aqueous chemical species in debris-rich basal glacier ice from Taylor Glacier, Antarctica were used as direct evidence that cells entrained in the ice remain metabolically active at temperatures as low as -17°C, likely in thin films of liquid water along ice crystal and mineral grain boundaries. δ18O2 and δ13CO2 values measured in the ice are consistent with the hypothesis that abrupt changes measured in O2 and CO2 concentrations between debris-rich and debris-poor ice are due to in situ microbial mineralization of organic carbon. Low temperature culture-based experiments conducted using organisms isolated from the ice indicate the ability to respire organic carbon to CO2 under oxic conditions and under anoxic conditions couple carbon mineralization to dissimilatory iron reduction using Fe3+ as an electron acceptor. Microorganisms that are active in the debris-rich basal ice layers in terrestrial polar ice masses need to be adapted to surviving subzero temperatures and saline conditions on extended timescales. Thus these terrestrial glacial systems and the isotopic and geochemical biomarkers therein provide good analogues for guiding exploration and analysis of debris-rich ices in extraterrestrial settings, for example, on Mars.

Freezing resistance in Patagonian woody shrubs: the role of cell wall elasticity and stem vessel size.

PubMed

Zhang, Yong-Jiang; Bucci, Sandra J; Arias, Nadia S; Scholz, Fabian G; Hao, Guang-You; Cao, Kun-Fang; Goldstein, Guillermo

2016-08-01

Freezing resistance through avoidance or tolerance of extracellular ice nucleation is important for plant survival in habitats with frequent subzero temperatures. However, the role of cell walls in leaf freezing resistance and the coordination between leaf and stem physiological processes under subzero temperatures are not well understood. We studied leaf and stem responses to freezing temperatures, leaf and stem supercooling, leaf bulk elastic modulus and stem xylem vessel size of six Patagonian shrub species from two sites (plateau and low elevation sites) with different elevation and minimum temperatures. Ice seeding was initiated in the stem and quickly spread to leaves, but two species from the plateau site had barriers against rapid spread of ice. Shrubs with xylem vessels smaller in diameter had greater stem supercooling capacity, i.e., ice nucleated at lower subzero temperatures. Only one species with the lowest ice nucleation temperature among all species studied exhibited freezing avoidance by substantial supercooling, while the rest were able to tolerate extracellular freezing from -11.3 to -20 °C. Leaves of species with more rigid cell walls (higher bulk elastic modulus) could survive freezing to lower subzero temperatures, suggesting that rigid cell walls potentially reduce the degree of physical injury to cell membranes during the extracellular freezing and/or thaw processes. In conclusion, our results reveal the temporal-spatial ice spreading pattern (from stem to leaves) in Patagonian shrubs, and indicate the role of xylem vessel size in determining supercooling capacity and the role of cell wall elasticity in determining leaf tolerance of extracellular ice formation. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Predehydration and Ice Seeding in the Presence of Trehalose Enable Cell Cryopreservation

PubMed Central

2017-01-01

Conventional approaches for cell cryopreservation require the use of toxic membrane-penetrating cryoprotective agents (pCPA), which limits the clinical application of cryopreserved cells. Here, we show intentionally induced ice formation at a high subzero temperature (> −10 °C) during cryopreservation, which is often referred to as ice seeding, could result in significant cell injury in the absence of any pCPA. This issue can be mitigated by predehydrating cells using extracellular trehalose to their minimal volume with minimized osmotically active water before ice seeding. We further observe that ice seeding can minimize the interfacial free energy that drives the devastating ice recrystallization-induced cell injury during warming cryopreserved samples. Indeed, by combining predehydration using extracellular trehalose with ice seeding at high subzero temperatures, high cell viability or recovery is achieved for fibroblasts, adult stem cells, and red blood cells after cryopreservation without using any pCPA. The pCPA-free technology developed in this study may greatly facilitate the long-term storage and ready availability of living cells, tissues, and organs that are of high demand by modern cell-based medicine. PMID:28824959

Osmotic and elastic adjustments in cold desert shrubs differing in rooting depth: coping with drought and subzero temperatures

Treesearch

Fabian G. Scholz; Sandra J. Bucci; Nadia Arias; Frederick C. Meinzer; Guillermo Goldstein

2012-01-01

Physiological adjustments to enhance tolerance or avoidance of summer drought and winter freezing were studied in shallow- to deep-rooted Patagonian cold desert shrubs. We measured leaf water potential, osmotic potential, tissue elasticity, stem hydraulic characteristics, and stomatal conductance across species throughout the year, and assessed tissue damage by subzero...

Why Earth cryopegs are interesting to astrobiologists?

NASA Astrophysics Data System (ADS)

Rivkina, Elizaveta; Spirina, Elena; Demidov, Nikita; Shcherbakova, Viktoria; Yoshikawa, Kenji; Gilichinsky, David

The lenses of perennially overcooled water brines (cryopegs) derived from ancient marine sedi-ments and sandwiched within permafrost 10 to 120,000 years ago after the placeArctic Ocean regressions. In these lenses freezing is prevented by freezing-point depression due to the dis-solved salt and they remain liquid at the in situ temperatures down to -11oC as a result of their high sodium-chloride concentration (3-5 mol/l). Cryopegs make up the only habitat on Earth that is characterized by permanently subzero temperatures, high salinity, and isolation from the influence of external factors during geological time. During last years the biodiversity of cryopeg's indigenous microbial community along the Arctic coast of placePlaceNamePolar PlaceTypeOcean (Kara and placeEast Siberian Sea, placePla-ceNameJamal PlaceTypePeninsula and placePlaceTypeCape PlaceNameBarrow) were studied and the new species representing the different genera have been isolated and described. There were found both aerobic and anaerobic microorganisms: Psychrobacters, Sulfate-reducers, Clostridia, etc. The isolated bacteria grew at subzero temperatures, and were also tolerant to salt concentra-tions up to metricconverterProductID3 M3 M NaCl. The microorganisms detected in cryopegs are halophilic and psychrophilic organisms at the same time. The microbial activity detected in cryopegs (14C-labeled glucose consumption) at temperatures as low as metricconverterProductID-15?C-15C-15° C documents the fact that subzero temper-atures themselves do not exclude biochemical reactions. In situ microbial activity and survival of microorganisms in a low-temperature high-salt aquatic environment on a geological time scale indicates the special type of microbial adaptation. From the astrobiological perspective, mineral-enriched brines provide the only opportunity for free water within the Martian subsurface permafrost, formed when Mars became dry and cold. These brines, just as terrestrial cryopegs, may contain microorganisms adapted to low tem-perature and high salinity. The halotolerant and halophilic, psychrophilic and psychrotrophic microbial community within Arctic water brines, represent the model of a plausible prototype for Martian microbial life. Based on the maps of temperature and salt distribution on the surface of Mars, areas most favorable for existence of cryopegs may be detected.

Does acute lead (Pb) contamination influence membrane fatty acid composition and freeze tolerance in intertidal blue mussels in arctic Greenland?

PubMed

Thyrring, Jakob; Juhl, Bodil Klein; Holmstrup, Martin; Blicher, Martin E; Sejr, Mikael K

2015-11-01

In their natural habitats, organisms are exposed to multiple stressors. Heavy metal contamination stresses the cell membrane due to increased peroxidation of lipids. Likewise, sub-zero air temperatures potentially reduce membrane functionality in ectothermal animals. We tested if acute lead (Pb) exposure for 7 days would influence survival in intertidal blue mussels (Mytilus edulis) after exposure to realistic sub-zero air temperatures. A full factorial experiment with five tissue Pb concentrations between 0 and 3500 μg Pb/g and six sub-zero temperatures from 0 to -17 °C were used to test the hypothesis that sub-lethal effects of Pb may increase the lethality caused by freezing in blue mussels exposed to temperatures simulating Greenland winter conditions. We found a significant effect of temperature on mortality. However, the short-term exposure to Pb did not result in any effects of Pb, nor did we find interactions between Pb and temperature. We analysed the relative abundance of major phospholipid fatty acids (PLFAs) in the gill tissue, but we found no significant effect of Pb tissue concentration on PLFA composition. Results suggest that Pb accumulation has limited effects on freeze tolerance and does not induce membrane damage in terms of persistent lipid peroxidation.

PLA and single component silicone rubber blends for sub-zero temperature blown film packaging applications

NASA Astrophysics Data System (ADS)

Meekum, Utai; Khiansanoi, Apichart

2018-06-01

The poly(lactic acid) (PLA) blend with single component silicone rubber in the presence of reactive amino silane coupling agent and polyester polyols plasticizer were studied. The manufacturing of film packaging for sub-zero temperature applications from the PLA blend was the main objective. The mechanical properties, especially the impact strengths, of PLA/silicone blends were significantly depended on the silicone loading. The outstanding impact strengths, tested at sub-zero temperature, of the blend having silicone content of 8.0 phr was achieved. It was chosen as the best candidate for the processability improvement. Adding the talc filler into the PLA/silicone blend to enhance the rheological properties was investigated. The ductility of the talc filled blends were decreased with increasing the filler contents. However, the shear viscosity of the blend was raised with talc loading. The blend loaded with 40 phr of talc filler was justified as the optimal formula for the blown film process testing and it was successfully performed with a few difficulties. The obtained blown film showed relative good flexibility in comparison with LDPE but it has low transparency.

Ice and anti-nucleating activities of an ice-binding protein from the annual grass, Brachypodium distachyon.

PubMed

Bredow, Melissa; Tomalty, Heather E; Smith, Lindsay; Walker, Virginia K

2018-05-01

Plants exposed to sub-zero temperatures face unique challenges that threaten their survival. The growth of ice crystals in the extracellular space can cause cellular dehydration, plasma membrane rupture and eventual cell death. Additionally, some pathogenic bacteria cause tissue damage by initiating ice crystal growth at high sub-zero temperatures through the use of ice-nucleating proteins (INPs), presumably to access nutrients from lysed cells. An annual species of brome grass, Brachypodium distachyon (Bd), produces an ice-binding protein (IBP) that shapes ice with a modest depression of the freezing point (~0.1 °C at 1 mg/mL), but high ice-recrystallization inhibition (IRI) activity, allowing ice crystals to remain small at near melting temperatures. This IBP, known as BdIRI, is unlike other characterized IBPs with a single ice-binding face, as mutational analysis indicates that BdIRI adsorbs to ice on two faces. BdIRI also dramatically attenuates the nucleation of ice by bacterial INPs (up to -2.26 °C). This 'anti-nucleating' activity is significantly higher than previously documented for any IBP. © 2016 John Wiley & Sons Ltd.

An Electrochemistry Study of Cryoelectrolysis in Frozen Physiological Saline.

PubMed

Manuel, Thomas J; Munnangi, Pujita; Rubinsky, Boris

2017-07-01

Cryoelectrolysis is a new minimally invasive tissue ablation surgical technique that combines the processes of electrolysis and solid/liquid phase transformation (freezing). This study investigated this new technique by measuring the pH front propagation and the changes in resistance in a tissue simulant made of physiological saline gel with a pH dye as a function of the sample temperature in the high subzero range above the eutectic. Results demonstrated that effective electrolysis can occur in a high subzero freezing milieu and that the propagation of the pH front is only weakly dependent on temperature. These observations are consistent with a mechanism involving ionic movement through the concentrated saline solution channels between ice crystals at subfreezing temperatures above the eutectic. Moreover, results suggest that Joule heating in these microchannels may cause local microscopic melting, the observed weak dependence of pH front propagation on temperature, and the large changes in resistance with time. A final insight provided by the results is that the pH front propagation from the anode is more rapid than from the cathode, a feature indicative of the electro-osmotic flow from the cathode to the anode. The findings in this paper may be critical for designing future cryoelectrolytic ablation surgery protocols.

Inflorescences of alpine cushion plants freeze autonomously and may survive subzero temperatures by supercooling

PubMed Central

Hacker, Jürgen; Ladinig, Ursula; Wagner, Johanna; Neuner, Gilbert

2011-01-01

Freezing patterns in the high alpine cushion plants Saxifraga bryoides, Saxifraga caesia, Saxifraga moschata and Silene acaulis were studied by infrared thermography at three reproductive stages (bud, anthesis, fruit development). The single reproductive shoots of a cushion froze independently in all four species at every reproductive stage. Ice formation caused lethal damage to the respective inflorescence. After ice nucleation, which occurred mainly in the stalk or the base of the reproductive shoot, ice propagated throughout that entire shoot, but not into neighboring shoots. However, anatomical ice barriers within cushions were not detected. The naturally occurring temperature gradient within the cushion appeared to interrupt ice propagation thermally. Consequently, every reproductive shoot needed an autonomous ice nucleation event to initiate freezing. Ice nucleation was not only influenced by minimum temperatures but also by the duration of exposure. At moderate subzero exposure temperatures (−4.3 to −7.7 °C) the number of frozen inflorescences increased exponentially. Due to efficient supercooling, single reproductive shoots remained unfrozen down to −17.4 °C (cooling rate 6 K h−1). Hence, the observed freezing pattern may be advantageous for frost survival of individual inflorescences and reproductive success of high alpine cushion plants, when during episodic summer frosts damage can be avoided by supercooling. PMID:21151351

Cold adaptive traits revealed by comparative genomic analysis of the eurypsychrophile Rhodococcus sp. JG3 isolated from high elevation McMurdo Dry Valley permafrost, Antarctica.

PubMed

Goordial, Jacqueline; Raymond-Bouchard, Isabelle; Zolotarov, Yevgen; de Bethencourt, Luis; Ronholm, Jennifer; Shapiro, Nicole; Woyke, Tanja; Stromvik, Martina; Greer, Charles W; Bakermans, Corien; Whyte, Lyle

2016-02-01

The permafrost soils of the high elevation McMurdo Dry Valleys are the most cold, desiccating and oligotrophic on Earth. Rhodococcus sp. JG3 is one of very few bacterial isolates from Antarctic Dry Valley permafrost, and displays subzero growth down to -5°C. To understand how Rhodococcus sp. JG3 is able to survive extreme permafrost conditions and be metabolically active at subzero temperatures, we sequenced its genome and compared it to the genomes of 14 mesophilic rhodococci. Rhodococcus sp. JG3 possessed a higher copy number of genes for general stress response, UV protection and protection from cold shock, osmotic stress and oxidative stress. We characterized genome wide molecular adaptations to cold, and identified genes that had amino acid compositions favourable for increased flexibility and functionality at low temperatures. Rhodococcus sp. JG3 possesses multiple complimentary strategies which may enable its survival in some of the harshest permafrost on Earth. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Health Impacts of Climate Change-Induced Subzero Temperature Fires.

PubMed

Metallinou, Maria-Monika; Log, Torgrim

2017-07-20

General fire risk and the special risk related to cold climate cellulosic drying processes are outlined. Four recent subzero temperatures fires are studied with respect to health impacts: a wooden village fire, a single wood structure fire, a wildland urban interface (WUI) fire and a huge wildland fire. The health impacts range from stress related to loss of jobs, psychological effects of lost possessions, exposure to smoke and heat as well as immediate, or delayed, loss of lives. These four fires resulted in 32 fatalities, 385 persons hospitalized for shorter or longer periods, 104 structures lost and 1015 km² of wildland burned north of, and just south of, the Arctic Circle. It is shown that the combination of subzero temperature dry weather, strong winds, changing agricultural activities and declining snowpack may lead to previously anticipated threats to people and the environment. There are reasons to believe that these fires are a result of the ongoing climate changes. Risk impacts are discussed. Rural districts and/or vulnerable populations seem to be most affected. Training methods to identify and better monitor critical fire risk parameters are suggested to mitigate the health impacts of a possibly increasing number of such fires.

Health Impacts of Climate Change-Induced Subzero Temperature Fires

PubMed Central

Metallinou, Maria-Monika; Log, Torgrim

2017-01-01

General fire risk and the special risk related to cold climate cellulosic drying processes are outlined. Four recent subzero temperatures fires are studied with respect to health impacts: a wooden village fire, a single wood structure fire, a wildland urban interface (WUI) fire and a huge wildland fire. The health impacts range from stress related to loss of jobs, psychological effects of lost possessions, exposure to smoke and heat as well as immediate, or delayed, loss of lives. These four fires resulted in 32 fatalities, 385 persons hospitalized for shorter or longer periods, 104 structures lost and 1015 km2 of wildland burned north of, and just south of, the Arctic Circle. It is shown that the combination of subzero temperature dry weather, strong winds, changing agricultural activities and declining snowpack may lead to previously anticipated threats to people and the environment. There are reasons to believe that these fires are a result of the ongoing climate changes. Risk impacts are discussed. Rural districts and/or vulnerable populations seem to be most affected. Training methods to identify and better monitor critical fire risk parameters are suggested to mitigate the health impacts of a possibly increasing number of such fires. PMID:28726752

AN EVALUATION OF PERSONAL SAMPLING PUMPS IN SUB-ZERO TEMPERATURES

EPA Science Inventory

Personal sampling pumps suitable for industrial hygiene surveys were evaluated to discover their characteristics as a function of temperature for temperatures between 25 and -50C. The pumps evaluated were significantly influenced by low temperatures. In general, most provided a s...

Freezing-induced cellular and membrane dehydration in the presence of cryoprotective agents.

PubMed

Akhoondi, Maryam; Oldenhof, Harriëtte; Sieme, Harald; Wolkers, Willem F

2012-09-01

FTIR and cryomicroscopy have been used to study mouse embryonic fibroblast cells (3T3) during freezing in the absence and presence of DMSO and glycerol. The results show that cell volume changes as observed by cryomicroscopy typically end at temperatures above -15°C, whereas membrane phase changes may continue until temperatures as low as -30°C. This implies that cellular dehydration precedes dehydration of the bound water surrounding the phospholipid head groups. Both DMSO and glycerol increase the membrane hydraulic permeability at subzero temperature and reduce the activation energy for water transport. Cryoprotective agents facilitate dehydration to continue at low subzero temperatures thereby decreasing the incidence of intracellular ice formation. The increased subzero membrane hydraulic permeability likely plays an important role in the cryoprotective action of DMSO and glycerol. In the presence of DMSO water permeability was found to be greater compared to that in the presence of glycerol. Two temperature regimes were identified in an Arrhenius plot of the membrane hydraulic permeability. The activation energy for water transport at temperature ranging from 0 to -10°C was found to be greater than that below -10°C. The non-linear Arrhenius behavior of Lp has been implemented in the water transport model to simulate cell volume changes during freezing. At a cooling rate of 1°C min(-1), ∼5% of the initial osmotically active water volume is trapped inside the cells at -30°C.

Probing anode degradation in automotive Li-ion batteries

NASA Astrophysics Data System (ADS)

Kwon, Ou Jung

The lithium-ion battery is drawing attention as a power source for future clean and fuel-efficient vehicles. Although the Li-ion battery presently shows best performance for energy density and power density compared to other rechargeable batteries, some degradation problems still remain as key challenges for long-term durability in automotive applications. Among those problems, Li deposition is well known for causing permanent capacity loss. Fundamental mechanisms of Li deposition in the carbon anode are, however, not fully understood, especially at subzero temperature and/or under high rate charge. This dissertation introduces comprehensive study of Li deposition using automotive 18650 Li-ion cells. The mechanism and relevant diagnostic methods as well as preventive charging protocol are discussed. In part one, a new diagnostic tool is introduced utilizing 3-electrode cell system, which measures thermodynamic and kinetic parameters of cathode and anode, respectively, as a function of temperature and SOC (state of charge): open circuit potential (OCP); Li diffusion coefficient in active particles; and internal resistance. These data are employed to understand electrochemical reaction and its thermal interaction under charging conditions that result in Li deposition. Part two provides a threshold parameter for the onset of Li deposition, which is not commonly used anode potential but charge capacity, or more specifically the amount of Li+ ions participating in intercalation reaction without Li deposition at given charging circumstances. This is called the critical charge capacity in this thesis, beyond which capacity loss at normal operating condition is observed, which becomes more serious as temperature is lowered and/or charge C-rate increases. Based on these experimental results, the mechanism of Li deposition is proposed as the concept of anode particle surface saturation, meaning that once the anode particle surface is saturated with Li in any charging circumstances, no more Li+ ions can be intercalated but should be reduced to metallic form on the anode particle surface. This is validated by calculating the distribution of Li concentration inside the anode particle with electrochemical modeling. In part three, a novel pulse charge protocol is developed, which consists of two steps. First high current charge/discharge pulses increase the cell temperature from a subzero temperature up to above room temperature in a short time, and next, high current charge provides the net charge capacity. Sluggish Li diffusion at low temperature becomes fast thanks to cell temperature elevation by high current pulses (1st step), which plays a role of preventing surface saturation during high current charge (2nd step). Thus, this charge protocol is not only Li deposition-free but also leads to rapid charge at subzero temperatures.

Mutagenic effect of freezing on nuclear DNA of Saccharomyces cerevisiae.

PubMed

Todorova, T; Pesheva, M; Stamenova, R; Dimitrov, M; Venkov, P

2012-05-01

Although fragmentation of DNA has been observed in cells undergoing freezing procedures, a mutagenic effect of sub-zero temperature treatment has not been proved by induction and isolation of mutants in nuclear DNA (nDNA). In this communication we supply evidence for mutagenicity of freezing on nDNA of Saccharomyces cerevisiae cells. In the absence of cryoprotectors, cooling for 2 h at +4°C and freezing for 1 h at -10°C and 16 h at -20°C, with a cooling rate of 3°C/min, resulted in induction of frame-shift and reverse mutations in microsatellite and coding regions of nDNA. The sub-zero temperature exposure also has a strong recombinogenic effect, evidenced by induction of gene-conversion and crossing-over events. Freezing induces mutations and enhances recombination with a frequency equal to or higher than that of methylmethanesulphonate at comparable survival rates. The signals for the appearance of nDNA lesions induced by freezing are detected and transduced by the DNA damage pathway. Extracellular cryoprotectors did not prevent the mutagenic effect of freezing, while accumulation of trehalose inside cells reduced nDNA cryodamage. Freezing of cells is accompanied by generation of high ROS levels, and the oxidative stress raised during the freeze-thaw process is the most likely reason for the DNA damaging effect. Experiments with mitochondrial rho⁻ mutants or scavengers of ROS indicated that mutagenic and recombinogenic effects of sub-zero temperatures can be decreased but not eliminated by reduction of ROS level. The complete protection against cryodamage in nDNA required simultaneous usage of intracellular cryoprotector and ROS scavenger during the freeze-thaw process. Copyright © 2012 John Wiley & Sons, Ltd.

Soil carbon distribution in Alaska in relation to soil-forming factors

Treesearch

Kristofer D. Johnson; Jennifer Harden; A. David McGuire; Norman B. Bliss; James G. Bockheim; Mark Clark; Teresa Nettleton-Hollingsworth; M. Torre Jorgenson; Evan S. Kane; Michelle Mack; Johathan ODonnell; Chien-Lu Ping; Edward A.G. Schuur; Merritt R. Turetsky; David W. Valentine

2011-01-01

The direction and magnitude of soil organic carbon (SOC) changes in response to climate change remain unclear and depend on the spatial distribution of SOC across landscapes. Uncertainties regarding the fate of SOC are greater in high-latitude systems where data are sparse and the soils are affected by sub-zero temperatures. To address these issues in Alaska, a first-...

The Effect of Prestrain Temperature on Kinetics of Static Recrystallization, Microstructure Evolution, and Mechanical Properties of Low Carbon Steel

NASA Astrophysics Data System (ADS)

Akbari, Edris; Karimi Taheri, Kourosh; Karimi Taheri, Ali

2018-05-01

In this research, the samples of a low carbon steel sheet were rolled up to a thickness prestrain of 67% at three different temperatures consisted of room, blue brittleness, and subzero temperature. Microhardness, SEM, and tensile tests were carried out to evaluate the static recrystallization kinetics defined by the Avrami equation, microstructural evolution, and mechanical properties. It was found that the Avrami exponent is altered with change in prestrain temperature and it achieves the value of 1 to 1. 5. Moreover, it was indicated that prestraining at subzero temperature followed by annealing at 600 °C leads to considerable enhancement in tensile properties and kinetics of static recrystallization compared to room and blue brittleness temperatures. The prestraining at blue brittleness temperature followed by annealing treatment caused, however, a higher strength and faster kinetics compared with that at room temperature. It was concluded that although from the steel ductility point of view, the blue brittleness temperature is called an unsuitable temperature, but it can be used as prestraining temperature to develop noticeable combination of strength and ductility in low carbon steel.

Effect of cryogenic treatment on microstructure, mechanical and wear behaviors of AISI H13 hot work tool steel

NASA Astrophysics Data System (ADS)

Koneshlou, Mahdi; Meshinchi Asl, Kaveh; Khomamizadeh, Farzad

2011-01-01

This paper focuses on the effects of low temperature (subzero) treatments on microstructure and mechanical properties of H13 hot work tool steel. Cryogenic treatment at -72 °C and deep cryogenic treatment at -196 °C were applied and it was found that by applying the subzero treatments, the retained austenite was transformed to martensite. As the temperature was decreased more retained austenite was transformed to martensite and it also led to smaller and more uniform martensite laths distributed in the microstructure. The deep cryogenic treatment also resulted in precipitation of more uniform and very fine carbide particles. The microstructural modification resulted in a significant improvement on the mechanical properties of the H13 tool steel.

Enhanced Microbial Survivability in Subzero Brines.

PubMed

Heinz, Jacob; Schirmack, Janosch; Airo, Alessandro; Kounaves, Samuel P; Schulze-Makuch, Dirk

2018-04-17

It is well known that dissolved salts can significantly lower the freezing point of water and thus extend habitability to subzero conditions. However, most investigations thus far have focused on sodium chloride as a solute. In this study, we report on the survivability of the bacterial strain Planococcus halocryophilus in sodium, magnesium, and calcium chloride or perchlorate solutions at temperatures ranging from +25°C to -30°C. In addition, we determined the survival rates of P. halocryophilus when subjected to multiple freeze/thaw cycles. We found that cells suspended in chloride-containing samples have markedly increased survival rates compared with those in perchlorate-containing samples. In both cases, the survival rates increase with lower temperatures; however, this effect is more pronounced in chloride-containing samples. Furthermore, we found that higher salt concentrations increase survival rates when cells are subjected to freeze/thaw cycles. Our findings have important implications not only for the habitability of cold environments on Earth but also for extraterrestrial environments such as that of Mars, where cold brines might exist in the subsurface and perhaps even appear temporarily at the surface such as at recurring slope lineae. Key Words: Brines-Halophile-Mars-Perchlorate-Subzero-Survival. Astrobiology 18, xxx-xxx.

Carbonate mineral solubility at low temperatures in the Na-K-Mg-Ca-H-Cl-SO 4-OH-HCO 3-CO 3-CO 2-H 2O system

NASA Astrophysics Data System (ADS)

Marion, Giles M.

2001-06-01

Carbonate minerals have played an important role in the geochemical evolution of Earth, and may have also played an important role in the geochemical evolution of Mars and Europa. Several models have been published in recent years that describe chloride and sulfate mineral solubilities in concentrated brines using the Pitzer equations. Few of these models are parameterized for subzero temperatures, and those that are do not include carbonate chemistry. The objectives of this work are to estimate Pitzer-equation bicarbonate-carbonate parameters and carbonate mineral solubility products and to incorporate them into the FREZCHEM model to predict carbonate mineral solubilities in the Na-K-Mg-Ca-H-Cl-SO 4-OH-HCO 3-CO 3-CO 2-H 2O system at low temperatures (≤25°C) with a special focus on subzero temperatures. Most of the Pitzer-equation parameters and equilibrium constants are taken from the literature and extrapolated into the subzero temperature range. Solubility products for 14 sodium, potassium, magnesium, and calcium bicarbonate and carbonate minerals are included in the model. Most of the experimental data are at temperatures ≥ -8°C; only for the NaHCO 3-NaCl-H 2O and Na 2CO 3-NaCl-H 2O systems are there bicarbonate and carbonate data to temperatures as low as -21.6°C. In general, the fit of the model to the experimental data is good. For example, calculated eutectic temperatures and compositions for NaHCO 3, Na 2CO 3, and their mixtures with NaCl and Na 2SO 4 salts are in good agreement with experimental data to temperatures as low as -21.6°C. Application of the model to eight saline, alkaline carbonate waters give predicted pHs ranging from 9.2 to 10.2, in comparison with measured pHs that range from 8.7 to 10.2. The model suggests that the CaCO 3 mineral that precipitates during seawater freezing is probably calcite and not ikaite. The model demonstrates that a proposed salt assemblage for the icy surface of Europa consisting of highly hydrated MgSO 4 salts and natron (Na 2CO 3 · 10H 2O) is an incompatible salt assemblage.

Ice nucleation and antinucleation in nature.

PubMed

Zachariassen, K E; Kristiansen, E

2000-12-01

Plants and ectothermic animals use a variety of substances and mechanisms to survive exposure to subfreezing temperatures. Proteinaceous ice nucleators trigger freezing at high subzero temperatures, either to provide cold protection from released heat of fusion or to establish a protective extracellular freezing in freeze-tolerant species. Freeze-avoiding species increase their supercooling potential by removing ice nucleators and accumulating polyols. Terrestrial invertebrates and polar marine fish stabilize their supercooled state by means of noncolligatively acting antifreeze proteins. Some organisms also depress their body fluid melting point to ambient temperature by evaporation and/or solute accumulation. Copyright 2000 Academic Press.

Animal ice-binding (antifreeze) proteins and glycolipids: an overview with emphasis on physiological function.

PubMed

Duman, John G

2015-06-01

Ice-binding proteins (IBPs) assist in subzero tolerance of multiple cold-tolerant organisms: animals, plants, fungi, bacteria etc. IBPs include: (1) antifreeze proteins (AFPs) with high thermal hysteresis antifreeze activity; (2) low thermal hysteresis IBPs; and (3) ice-nucleating proteins (INPs). Several structurally different IBPs have evolved, even within related taxa. Proteins that produce thermal hysteresis inhibit freezing by a non-colligative mechanism, whereby they adsorb onto ice crystals or ice-nucleating surfaces and prevent further growth. This lowers the so-called hysteretic freezing point below the normal equilibrium freezing/melting point, producing a difference between the two, termed thermal hysteresis. True AFPs with high thermal hysteresis are found in freeze-avoiding animals (those that must prevent freezing, as they die if frozen) especially marine fish, insects and other terrestrial arthropods where they function to prevent freezing at temperatures below those commonly experienced by the organism. Low thermal hysteresis IBPs are found in freeze-tolerant organisms (those able to survive extracellular freezing), and function to inhibit recrystallization - a potentially damaging process whereby larger ice crystals grow at the expense of smaller ones - and in some cases, prevent lethal propagation of extracellular ice into the cytoplasm. Ice-nucleator proteins inhibit supercooling and induce freezing in the extracellular fluid at high subzero temperatures in many freeze-tolerant species, thereby allowing them to control the location and temperature of ice nucleation, and the rate of ice growth. Numerous nuances to these functions have evolved. Antifreeze glycolipids with significant thermal hysteresis activity were recently identified in insects, frogs and plants. © 2015. Published by The Company of Biologists Ltd.

77 FR 73415 - Approval for Manufacturing Authority; Foreign-Trade Zone 277; Sub-Zero, Inc. (Refrigerators and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-10

... Authority; Foreign-Trade Zone 277; Sub-Zero, Inc. (Refrigerators and Freezers); Goodyear, AZ Pursuant to its... Foreign Trade Zone, Inc., grantee of FTZ 277, has requested manufacturing authority on behalf of Sub-Zero... procedures within FTZ 277 on behalf of Sub-Zero, Inc., as described in the application and Federal Register...

Low-temperature Ignition-delay Characteristics of Several Rocket Fuels with Mixed Acid in Modified Open-cup-type Apparatus

NASA Technical Reports Server (NTRS)

Miller, Riley O

1950-01-01

Summaries of low-temperature self-ignition data of various rocket fuels with mixed acid (nitric plus sulfuric) are presented. Several fuels are shown to have shorter ignition-delay intervals and less variation in delay intervals at moderate and sub-zero temperatures than crude N-ethylaniline (monoethylaniline),a rocket fuel in current use.

76 FR 71335 - Publication of the Petition for Waiver and Notice of Granting the Application for Interim Waiver...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-17

...] Publication of the Petition for Waiver and Notice of Granting the Application for Interim Waiver of Sub-Zero... notice announces receipt of and publishes the Sub-Zero, Inc. (Sub-Zero) petition for waiver (hereafter... pertains to the basic models set forth in Sub-Zero's petition that incorporate dual compressors. In its...

Toward understanding life under subzero conditions: the significance of exploring psychrophilic "cold-shock" proteins.

PubMed

Kuhn, Emanuele

2012-11-01

Understanding the behavior of proteins under freezing conditions is vital for detecting and locating extraterrestrial life in cold environments, such as those found on Mars and the icy moons of Jupiter and Saturn. This review highlights the importance of studying psychrophilic "cold-shock" proteins, a topic that has yet to be explored. A strategy for analyzing the psychrophilic RNA helicase protein CsdA (Psyc_1082) from Psychrobacter arcticus 273-4 as a key protein for life under freezing temperatures is proposed. The experimental model presented here was developed based on previous data from investigations of Escherichia coli, P. arcticus 273-4, and RNA helicases. P. arcticus 273-4 is considered a model for life in freezing environments. It is capable of growing in temperatures as cold as -10°C by using physiological strategies to survive not only in freezing temperatures but also under low-water-activity and limited-nutrient-availability conditions. The analyses of its genome, transcriptome, and proteome revealed specific adaptations that allow it to inhabit freezing environments by adopting a slow metabolic strategy rather than a cellular dormancy state. During growth at subzero temperatures, P. arcticus 273-4 genes related to energy metabolism and carbon substrate incorporation are downregulated, and genes for maintenance of membranes, cell walls, and nucleic acid motion are upregulated. At -6°C, P. arcticus 273-4 does not upregulate the expression of either RNA or protein chaperones; however, it upregulates the expression of its cold-shock induced DEAD-box RNA helicase protein A (CsdA - Psyc_1082). CsdA - Psyc_1082 was investigated as a key helper protein for sustaining life in subzero conditions. Proving CsdA - Psyc_1082 to be functional as a key protein for life under freezing temperatures may extend the known minimum growth temperature of a mesophilic cell and provide key information about the mechanisms that underlie cold-induced biological systems in icy worlds.

Motility of Colwellia psychrerythraea Strain 34H at Subzero Temperatures

PubMed Central

Junge, Karen; Eicken, Hajo; Deming, Jody W.

2003-01-01

We examined the Arctic bacterium Colwellia psychrerythraea strain 34H for motility at temperatures from −1 to −15°C by using transmitted-light microscopy in a temperature-controlled laboratory. The results, showing motility to −10°C, indicate much lower temperatures to be permissive of motility than previously reported (5°C), with implications for microbial activity in frozen environments. PMID:12839815

Full temperature single event upset characterization of two microprocessor technologies

NASA Technical Reports Server (NTRS)

Nichols, Donald K.; Coss, James R.; Smith, L. S.; Rax, Bernard; Huebner, Mark

1988-01-01

Data for the 9450 I3L bipolar microprocessor and the 80C86 CMOS/epi (vintage 1985) microprocessor are presented, showing single-event soft errors for the full MIL-SPEC temperature range of -55 to 125 C. These data show for the first time that the soft-error cross sections continue to decrease with decreasing temperature at subzero temperatures. The temperature dependence of the two parts, however, is very different.

Magnetic resonance tells microbiology where to go; bacterial teichoic acid protects liquid water at sub-zero temperatures

NASA Astrophysics Data System (ADS)

Rice, Charles V.; Wickham, Jason R.; Eastman, Margaret A.; Harrison, William; Pereira, Mark P.; Brown, Eric D.

2008-08-01

Numerous chemical additives lower the freezing point of water, but life at sub-zero temperatures is sustained by a limited number of biological cryoprotectants. Antifreeze proteins in fish, plants, and insects provide protection to a few degrees below freezing. Microbes have been found to survive at even lower temperatures, although, with a few exceptions, antifreeze proteins are missing. Survival has been attributed to external factors, such as high salt concentration (brine veins) and adhesion to particulates or ice crystal defects. Teichoic acid is a phosphodiester polymer ubiquitous in Gram positive bacteria, composing 50% of the mass of the bacterial cell wall and excreted into the extracellular space of biofilm communities. We have found that when bound to the peptidoglycan cell wall (wall teichoic acid) or as a free molecule (lipoteichoic acid), teichoic acid is surrounded by liquid water at temperatures significantly below freezing. Using solid-state NMR, we are unable to collect 31P CPMAS spectra for frozen solutions of lipoteichoic acid at temperatures above -60 °C. For wall teichoic acid in D2O, signals are not seen above -30 °C. These results can be explained by the presence of liquid water, which permits rapid molecular motion to remove 1H/31P dipolar coupling. 2H quadrupole echo NMR spectroscopy reveals that both liquid and solid water are present. We suggest that teichoic acids could provide a shell of liquid water around biofilms and planktonic bacteria, removing the need for brine veins to prevent bacterial freezing.

Bending cyclic load test for crystalline silicon photovoltaic modules

NASA Astrophysics Data System (ADS)

Suzuki, Soh; Doi, Takuya; Masuda, Atsushi; Tanahashi, Tadanori

2018-02-01

The failures induced by thermomechanical fatigue within crystalline silicon photovoltaic modules are a common issue that can occur in any climate. In order to understand these failures, we confirmed the effects of compressive or tensile stresses (which were cyclically loaded on photovoltaic cells and cell interconnect ribbons) at subzero, moderate, and high temperatures. We found that cell cracks were induced predominantly at low temperatures, irrespective of the compression or tension applied to the cells, although the orientation of cell cracks was dependent on the stress applied. The fracture of cell interconnect ribbons was caused by cyclical compressive stress at moderate and high temperatures, and this failure was promoted by the elevation of temperature. On the basis of these results, the causes of these failures are comprehensively discussed in relation to the viscoelasticity of the encapsulant.

Subzero-Temperature Liquid-Liquid Extraction Coupled with UPLC-MS-MS for the Simultaneous Determination of 12 Bioactive Components in Traditional Chinese Medicine Gegen-Qinlian Decoction.

PubMed

Shi, Zhihong; Li, Zhimin; Zhang, Shulan; Fu, Hongna; Zhang, Hongyi

2015-09-01

Based on the phase separation phenomenon of acetonitrile-water system at subzero temperature, a subzero-temperature liquid-liquid extraction coupled with ultra-performance liquid chromatography tandem quadrupole mass spectrometry : UPLC-MS-MS) method was developed for the simultaneous determination of 12 bioactive components in Gegen-Qinlian decoction. After optimization, the extraction conditions were set as follows: 3.0 mL of aqueous sample solution (pH 5.86) was extracted with 2 mL of acetonitrile at -35°C for 35 min. The separated acetonitrile phase was diluted 10-fold with water before UPLC-MS-MS analysis. Separation was performed on a Waters ACQUITY UPLC(®)BEH C18 column (2.1 × 100 mm i.d., 1.7 µm) with ammonium formate buffer solution (20 mmol L(-1), pH 3.2, adjusted by formic acid) and acetonitrile as mobile phase with gradient elution. Twelve target components could be separated within 10 min and quantified in multiple reaction monitoring mode, both positive and negative ionization modes were employed. Limits of detection were in the range of 0.0003-0.0451 μg mL(-1). Relative standard deviation values for intra- and interday precision were <2.71 and 8.94%, respectively. The established method provides a simple and effective framework for the quality control of Gegen-Qinlian decoction and related traditional Chinese medicinal preparations. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

POSS-Based Electrolyte for Efficient Solid-State Dye-Sensitized Solar Cells at Sub-Zero Temperatures.

PubMed

Lv, Kai; Zhang, Wei; Zhang, Lu; Wang, Zhong-Sheng

2016-03-02

To expand the application of solid-state dye-sensitized solar cells (ssDSSCs) to low temperatures, it is necessary to develop new solid electrolytes with low glass transition temperature (Tg). The Tg is regulated by varying the length of alkyl chain that is connected with the nitrogen atom in the imidazolium ring linked to the polyhedral oligomeric silsesquioxane (POSS). The Tg as low as -8.8 °C is achieved with the POSS grafted with methyl-substituted imidazolium. The effect of alkyl group on the conductivity, Tg, and photovoltaic performance has also been investigated. The conductivity and power conversion efficiency increase with the alkyl length, while the Tg first increases and then decreases with the alkyl length. Among the synthesized POSS-based ionic conductors, the POSS grafted with the methyl-substituted imidazolium yields the highest power conversion efficiency of 6.98% at RT due to its highest conductivity, and the efficiency (6.52%) is still good at -4 °C, as its Tg (-8.8 °C) is lower than the working temperature (-4 °C). This finding suggests that the POSS-based solid electrolyte is promising for subzero-temperature applications of ssDSSCs.

Cryosurgery with pulsed electric fields.

PubMed

Daniels, Charlotte S; Rubinsky, Boris

2011-01-01

This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to ablate cells in the high subzero freezing region of a cryosurgical lesion.

Physiological characteristics of bacteria isolated from water brines within permafrost

NASA Astrophysics Data System (ADS)

Shcherbakova, V.; Rivkina, E.; Laurinavichuis, K.; Pecheritsina, S.; Gilichinsky, D.

2004-01-01

In the Arctic there are lenses of overcooled water brines (cryopegs) sandwiched within permafrost marine sediments 100 120 thousand years old. We have investigated the physiological properties of the pure cultures of anaerobic Clostridium sp. strain 14D1 and two strains of aerobic bacteria Psychrobacter sp. isolated from these cryopegs. The structural and physiological characteristics of new bacteria from water brines have shown their ability to survive and develop under harsh conditions, such as subzero temperatures and high salinity.

Membrane stability of winter wheat plants exposed to subzero temperatures for variable lengths of time

USDA-ARS?s Scientific Manuscript database

The ability to survive episodes of subfreezing temperature is essential to winter wheat. Fully cold-acclimated plants of six lines of winter wheat were exposed to -12, -14, -16 or -18° C, four 1-5 hours. Electrolyte leakage and plant survival were used to assess damage to the plants. Plants exposed ...

Freezing avoidance by supercooling in Olea europaea cultivars: the role of apoplastic water, solute content and cell wall rigidity.

PubMed

Arias, Nadia S; Bucci, Sandra J; Scholz, Fabian G; Goldstein, Guillermo

2015-10-01

Plants can avoid freezing damage by preventing extracellular ice formation below the equilibrium freezing temperature (supercooling). We used Olea europaea cultivars to assess which traits contribute to avoid ice nucleation at sub-zero temperatures. Seasonal leaf water relations, non-structural carbohydrates, nitrogen and tissue damage and ice nucleation temperatures in different plant parts were determined in five cultivars growing in the Patagonian cold desert. Ice seeding in roots occurred at higher temperatures than in stems and leaves. Leaves of cold acclimated cultivars supercooled down to -13 °C, substantially lower than the minimum air temperatures observed in the study site. During winter, leaf ice nucleation and leaf freezing damage (LT50 ) occurred at similar temperatures, typical of plant tissues that supercool. Higher leaf density and cell wall rigidity were observed during winter, consistent with a substantial acclimation to sub-zero temperatures. Larger supercooling capacity and lower LT50 were observed in cold-acclimated cultivars with higher osmotically active solute content, higher tissue elastic adjustments and lower apoplastic water. Irreversible leaf damage was only observed in laboratory experiments at very low temperatures, but not in the field. A comparative analysis of closely related plants avoids phylogenetic independence bias in a comparative study of adaptations to survive low temperatures. © 2015 John Wiley & Sons Ltd.

Startup of air-cooled condensers and dry cooling towers at low temperatures of the cooling air

NASA Astrophysics Data System (ADS)

Milman, O. O.; Ptakhin, A. V.; Kondratev, A. V.; Shifrin, B. A.; Yankov, G. G.

2016-05-01

The problems of startup and performance of air-cooled condensers (ACC) and dry cooling towers (DCT) at low cooling air temperatures are considered. Effects of the startup of the ACC at sub-zero temperatures are described. Different options of the ACC heating up are analyzed, and examples of existing technologies are presented (electric heating, heating up with hot air or steam, and internal and external heating). The use of additional heat exchanging sections, steam tracers, in the DCT design is described. The need for high power in cases of electric heating and heating up with hot air is noted. An experimental stand for research and testing of the ACC startup at low temperatures is described. The design of the three-pass ACC unit is given, and its advantages over classical single-pass design at low temperatures are listed. The formation of ice plugs inside the heat exchanging tubes during the start-up of ACC and DCT at low cooling air temperatures is analyzed. Experimental data on the effect of the steam flow rate, steam nozzle distance from the heat-exchange surface, and their orientation in space on the metal temperature were collected, and test results are analyzed. It is noted that the surface temperature at the end of the heat up is almost independent from its initial temperature. Recommendations for the safe start-up of ACCs and DCTs are given. The heating flow necessary to sufficiently heat up heat-exchange surfaces of ACCs and DCTs for the safe startup is estimated. The technology and the process of the heat up of the ACC with the heating steam external supply are described by the example of the startup of the full-scale section of the ACC at sub-zero temperatures of the cooling air, and the advantages of the proposed start-up technology are confirmed.

Effect of 0.1 wt.% Co on the Hot Deformation and Toughness of Fine-Grained Low-Carbon Steel at Sub-zero Temperatures

NASA Astrophysics Data System (ADS)

Liu, Xiqin; Zhou, Shuangshuang; Liu, Zili; Hou, Zhiguo; Tian, Qingchao

2017-12-01

The effect of 0.1 wt.% Co on the hot deformation behavior of fine-grained low-carbon microalloyed steel was investigated at temperatures of 850-1200 °C and a strain rate of 5 s-1. Furthermore, the toughness of the steel with and without Co at sub-zero temperatures was evaluated. The results suggest that the addition of 0.1 wt.% Co increases the flow stress and delays the occurrence of dynamic recrystallization (DRX) at the same deformation temperature and strain. The DRX fraction of steel specimens without and with 0.1 wt.% Co was about 67.4 and 43.9% at 850 °C, respectively. Then, it increased to 100% at 1100 °C. Compared with steel without Co, cementite particles in the tempered sorbite of steel with 0.1 wt.% Co decreased in size but increased in quantity, yield strength increased from 756 to 787 MPa, and Charpy V-notch energy at - 20 and - 50 °C improved from 69 and 41 to 102 and 65 J, respectively. The fracture morphology and crack propagation characteristics were consistent with the variation in impact energy.

Effect of 0.1 wt.% Co on the Hot Deformation and Toughness of Fine-Grained Low-Carbon Steel at Sub-zero Temperatures

NASA Astrophysics Data System (ADS)

Liu, Xiqin; Zhou, Shuangshuang; Liu, Zili; Hou, Zhiguo; Tian, Qingchao

2018-01-01

The effect of 0.1 wt.% Co on the hot deformation behavior of fine-grained low-carbon microalloyed steel was investigated at temperatures of 850-1200 °C and a strain rate of 5 s-1. Furthermore, the toughness of the steel with and without Co at sub-zero temperatures was evaluated. The results suggest that the addition of 0.1 wt.% Co increases the flow stress and delays the occurrence of dynamic recrystallization (DRX) at the same deformation temperature and strain. The DRX fraction of steel specimens without and with 0.1 wt.% Co was about 67.4 and 43.9% at 850 °C, respectively. Then, it increased to 100% at 1100 °C. Compared with steel without Co, cementite particles in the tempered sorbite of steel with 0.1 wt.% Co decreased in size but increased in quantity, yield strength increased from 756 to 787 MPa, and Charpy V-notch energy at - 20 and - 50 °C improved from 69 and 41 to 102 and 65 J, respectively. The fracture morphology and crack propagation characteristics were consistent with the variation in impact energy.

Clinical trial of a novel surface cooling system for fever control in neurocritical care patients.

PubMed

Mayer, Stephan A; Kowalski, Robert G; Presciutti, Mary; Ostapkovich, Noeleen D; McGann, Elaine; Fitzsimmons, Brian-Fred; Yavagal, Dileep R; Du, Y Evelyn; Naidech, Andrew M; Janjua, Nazli A; Claassen, Jan; Kreiter, Kurt T; Parra, Augusto; Commichau, Christopher

2004-12-01

To compare the efficacy of a novel water-circulating surface cooling system with conventional measures for treating fever in neuro-intensive care unit patients. Prospective, unblinded, randomized controlled trial. Neurologic intensive care unit in an urban teaching hospital. Forty-seven patients, the majority of whom were mechanically ventilated and sedated, with fever > or =38.3 degrees C for >2 consecutive hours after receiving 650 mg of acetaminophen. Subjects were randomly assigned to 24 hrs of treatment with a conventional water-circulating cooling blanket placed over the patient (Cincinnati SubZero, Cincinnati OH) or the Arctic Sun Temperature Management System (Medivance, Louisville CO), which employs hydrogel-coated water-circulating energy transfer pads applied directly to the trunk and thighs. Diagnoses included subarachnoid hemorrhage (60%), cerebral infarction (23%), intracerebral hemorrhage (11%), and traumatic brain injury (4%). The groups were matched in terms of baseline variables, although mean temperature was slightly higher at baseline in the Arctic Sun group (38.8 vs. 38.3 degrees C, p = .046). Compared with patients treated with the SubZero blanket (n = 24), Arctic Sun-treated patients (n = 23) experienced a 75% reduction in fever burden (median 4.1 vs. 16.1 C degrees -hrs, p = .001). Arctic Sun-treated patients also spent less percent time febrile (T > or =38.3 degrees C, 8% vs. 42%, p < .001), spent more percent time normothermic (T < or =37.2 degrees C, 59% vs. 3%, p < .001), and attained normothermia faster than the SubZero group median (2.4 vs. 8.9 hrs, p = .008). Shivering occurred more frequently in the Arctic Sun group (39% vs. 8%, p = .013). The Arctic Sun Temperature Management System is superior to conventional cooling-blanket therapy for controlling fever in critically ill neurologic patients.

Membrane hydraulic permeability changes during cooling of mammalian cells.

PubMed

Akhoondi, Maryam; Oldenhof, Harriëtte; Stoll, Christoph; Sieme, Harald; Wolkers, Willem F

2011-03-01

In order to predict optimal cooling rates for cryopreservation of cells, the cell-specific membrane hydraulic permeability and corresponding activation energy for water transport need to be experimentally determined. These parameters should preferably be determined at subzero temperatures in the presence of ice. There is, however, a lack of methods to study membrane properties of cells in the presence of ice. We have used Fourier transform infrared spectroscopy to study freezing-induced membrane dehydration of mouse embryonic fibroblast (3T3) cells and derived the subzero membrane hydraulic permeability and the activation energy for water transport from these data. Coulter counter measurements were used to determine the suprazero membrane hydraulic permeability parameters from cellular volume changes of cells exposed to osmotic stress. The activation energy for water transport in the ice phase is about three fold greater compared to that at suprazero temperatures. The membrane hydraulic permeability at 0 °C that was extrapolated from suprazero measurements is about five fold greater compared to that extrapolated from subzero measurements. This difference is likely due to a freezing-induced dehydration of the bound water around the phospholipid head groups. Using Fourier transform infrared spectroscopy, two distinct water transport processes, that of free and membrane bound water, can be identified during freezing with distinct activation energies. Dimethylsulfoxide, a widely used cryoprotective agent, did not prevent freezing-induced membrane dehydration but decreased the activation energy for water transport. Copyright © 2010 Elsevier B.V. All rights reserved.

Successful introgression of abiotic stress tolerance from wild tepary bean to common bean

USDA-ARS?s Scientific Manuscript database

Common bean (Phaseolus vulgaris L.) production is severely limited due to abiotic stresses, including drought and sub-zero temperatures. Tepary bean (Phaseolus acutifolius Gray), a relative of common bean, has demonstrated tolerance to these stresses. Preliminary studies screening tepary accessions ...

High post-thaw survival of ram sperm after partial freeze-drying.

PubMed

Arav, Amir; Idda, Antonella; Nieddu, Stefano Mario; Natan, Yehudit; Ledda, Sergio

2018-03-14

Recrystallization damages occur when a frozen sample is held at high subzero temperatures and when the warming process is too slow. In this work, ram semen diluted in two different concentrations of sugar solutions (Lyo A consisted of 0.4 M sorbitol and 0.25 M trehalose, and the second, Lyo B composed of 0.26 M sorbitol and 0.165 M trehalose) in egg yolk and Tris medium were compared after freezing 10 μL samples to: (1) - 10, - 25, and - 35 °C and thawing. (2) Freezing to - 10 and - 25 °C, holding for 1 h and then thawing, and (3) freezing to - 10 and - 25 °C and drying for 1 h at these temperatures at a vacuum of 80 mTorr, prior thawing. For drying, we used a new freeze-drying apparatus (Darya, FertileSafe, Israel) having a condensation temperature below - 110 °C and a vacuum pressure of 10-100 mTorr that is reached in less than 10s. Results showed that samples in Lyo B solution frozen at - 25 °C had significantly higher sperm motility in partially freeze-dried samples than frozen samples (46.6 ± 2.8% vs 1.2 ± 2.5%, P < 0.001). Moreover, partially dried samples in Lyo B showed higher motility than Lyo A at - 25 °C (46.6 ± 2.8% vs 35 ± 4%). Cryomicroscopy and low-temperature/low-pressure environmental scanning electronic microscope demonstrated that the amount of the ice crystals present in partially dried samples was lower than in the frozen samples. Holding the sperm at high subzero temperatures is necessary for the primary drying of cells during the freeze-drying process. Rapid freeze-drying can be achieved using this new device, which enables to reduce recrystallization damages.

Evidence for marine origin and microbial-viral habitability of sub-zero hypersaline aqueous inclusions within permafrost near Barrow, Alaska.

PubMed

Colangelo-Lillis, J; Eicken, H; Carpenter, S D; Deming, J W

2016-05-01

Cryopegs are sub-surface hypersaline brines at sub-zero temperatures within permafrost; their global extent and distribution are unknown. The permafrost barrier to surface and groundwater advection maintains these brines as semi-isolated systems over geological time. A cryopeg 7 m below ground near Barrow, Alaska, was sampled for geochemical and microbiological analysis. Sub-surface brines (in situtemperature of -6 °C, salinity of 115 ppt), and an associated sediment-infused ice wedge (melt salinity of 0.04 ppt) were sampled using sterile technique. Major ionic concentrations in the brine corresponded more closely to other (Siberian) cryopegs than to Standard seawater or the ice wedge. Ionic ratios and stable isotope analysis of water conformed to a marine or brackish origin with subsequent Rayleigh fractionation. The brine contained ∼1000× more bacteria than surrounding ice, relatively high viral numbers suggestive of infection and reproduction, and an unusually high ratio of particulate to dissolved extracellular polysaccharide substances. A viral metagenome indicated a high frequency of temperate viruses and limited viral diversity compared to surface environments, with closest similarity to low water activity environments. Interpretations of the results underscore the isolation of these underexplored microbial ecosystems from past and present oceans. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Investigation on the Effect of Sub-Zero Treatment on Micro-Hardness and Microstructure of GTAW Welded Al-Si-Mg-Mn Alloy

NASA Astrophysics Data System (ADS)

Devanathan, R.; Yuvarajan, D.; Christopher Selvam, D.; Venkatamuni, T.

2018-02-01

In this work, the effect of sub-zero treatment on the mechanical properties of an Al-Si-Mg-Mn alloy welded by GTAW (gas tungsten arc welding) leads to significant softening in the welded region. The latter is due to melting and resolidification in the welded region, which have resulted in decomposition of the strengthening precipitates. The experiments were performed on GTAW welded plates of 6 mm thickness by varying the heat inputs, namely, of 370, 317.1, 277.5, 246.4, and 222 J/mm, and sub-zero treatment time periods. The Sub-Zero treatment was performed at-45°C using dry ice; hardness and microstructure investigations were performed in the welded region of the Al‒Si-Mg-Mn alloy that was studied in two different conditions, namely, as-welded and in that formed after post weld sub-zero treatment with artificial aging. It was found that the post weld Sub-Zero treatment followed by artificial aging had led to realization of significantly higher hardness values in the welded region due to the recurrence of the precipitation sequence.

Cryosurgery with Pulsed Electric Fields

PubMed Central

Daniels, Charlotte S.; Rubinsky, Boris

2011-01-01

This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to ablate cells in the high subzero freezing region of a cryosurgical lesion. PMID:22087224

Frostbite of the liver: an unrecognized cause of primary non-function?

PubMed

Potanos, Kristina; Kim, Heung Bae

2014-02-01

Appropriate hypothermic packaging techniques are an essential part of organ procurement. We present a case in which deviation from standard packaging practice may have caused sub-zero storage temperatures during transport, resulting in a clinical picture resembling PNF. An 18-month-old male with alpha-1-antitrypsin deficiency underwent liver transplant from a size-matched pediatric donor. Upon arrival at the recipient hospital, ice crystals were noted in the UW solution. The transplant proceeded uneventfully with short ischemia times. Surprisingly, transaminases, INR, and total bilirubin were markedly elevated in the postoperative period but returned to near normal by discharge. Follow-up of over five yr has demonstrated normal liver function. Upon review, it was discovered that organ packaging during recovery included storage in the first bag with only 400 mL of UW solution, and pure ice in the second bag instead of slush. This suggests that the postoperative delayed graft function was related to sub-zero storage of the graft during transport. This is the first report of sub-zero cold injury, or frostbite, following inappropriate packaging of an otherwise healthy donor liver. The clinical picture closely resembled PNF, perhaps implicating this mechanism in other unexpected cases of graft non-function. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Persistent supercooling of reproductive shoots is enabled by structural ice barriers being active despite an intact xylem connection

USDA-ARS?s Scientific Manuscript database

Extracellular ice nucleation usually occurs at mild subzero temperatures in most plants. For persistent supercooling of certain plant parts ice barriers are necessary that prevent the entry of ice from otherwise already frozen tissues. The reproductive shoot of the evergreen woody dwarf shrub Callun...

DOE Office of Scientific and Technical Information (OSTI.GOV)

New inverter-driven ASHPs are gaining ground in colder climates. These systems operate at sub-zero temperatures without the use of electric resistance backup. There are still uncertainties, however, about cold-climate capacity and efficiency in cold weather and questions such as measuring: power consumption, supply, return, and outdoor air temperatures, and air flow through the indoor fan coil. CARB observed a wide range of operating efficiencies and outputs from site to site. Maximum capacities were found to be generally in line with manufacturer's claims as outdoor temperatures fell to -10 degrees F. The reasons for the wide range in heating performance likelymore » include: low indoor air flow rates, poor placement of outdoor units, relatively high return air temperatures, thermostat set back, integration with existing heating systems, and occupants limiting indoor fan speed. Even with lower efficiencies than published in other studies, most of the heat pumps here still provide heat at lower cost than oil, propane, or certainly electric resistance systems.« less

Physiological Mechanisms Only Tell Half Story: Multiple Biological Processes are involved in Regulating Freezing Tolerance of Imbibed Lactuca sativa Seeds

PubMed Central

Jaganathan, Ganesh K.; Han, Yingying; Li, Weijie; Song, Danping; Song, Xiaoyan; Shen, Mengqi; Zhou, Qiang; Zhang, Chenxue; Liu, Baolin

2017-01-01

The physiological mechanisms by which imbibed seeds survive freezing temperatures in their natural environment have been categorized as freezing avoidance by supercooling and freezing tolerance by extracellular freeze-desiccation, but the biochemical and molecular mechanisms conferring seed freezing tolerance is unexplored. In this study, using imbibed Lactuca sativa seeds we show that fast cooled seeds (60 °C h−1) suffered significantly higher membrane damage at temperature between −20 °C and −10 °C than slow cooled (3 °Ch−1) seeds (P < 0.05), presumably explaining viability loss during fast cooling when temperature approaches −20 °C. Total soluble sugars increase in low temperature environment, but did not differ significantly between two cooling rates (P > 0.05). However, both SOD activity and accumulation of free proline were induced significantly after slow cooling to −20 °C compared with fast cooling. RNA-seq demonstrated that multiple pathways were differentially regulated between slow and fast cooling. Real-time verification of some differentially expressed genes (DEGs) revealed that fast cooling caused mRNA level changes of plant hormone and ubiquitionation pathways at higher sub-zero temperature, whilst slow cooling caused mRNA level change of those pathways at lower sub-zero ttemperatures. Thus, we conclude that imbibed seed tolerate low temperature not only by physiological mechanisms but also by biochemical and molecular changes. PMID:28287125

Strength of initially virgin martensites at - 196 °C after aging and tempering

NASA Astrophysics Data System (ADS)

Eldis, George T.; Cohen, Morris

1983-06-01

The compressive strength at -196°C of martensites in Fe-0.26 pct C-24 pct Ni, Fe-0.4 pct C-21 pct Ni, and Fe-0.4 pct C-18 pct Ni-3 pct Mo alloys, all with subzero M temperatures, has been determined in the virgin condition and after one hour at temperatures from -80 to +400 °C. The effects of ausforming (20 pct reduction in area of the austenite by swaging at room temperature prior to the martensitic transformation) were also investigated. For the unausformed martensites, aging at temperatures up to 0 °C results in relatively small increases in strength. Above 0 °C, the age hardening increment increases rapidly, reaching a maximum at 100 °C. Above 100 °C, the strength decreases continuously with increasing tempering temperature except for the molybdenum-containing alloy, which exhibits secondary hardening on tempering at 400 °C. For the ausformed martensites, the response to aging at subzero temperatures is greater than for unausformed material. Strength again passes through a maximum on aging at 100 °C. However, on tempering just above 100 °C, the ausformed materials show a slower rate of softening than the unausformed martensites. The strengthening produced by the ausforming treatment is largest for the Fe-0.4 pct C-18 pct Ni-3 pct Mo alloy, but there is no evidence of carbide precipitation in the deformed austenite to a°Count for this effect of molybdenum.

Physiological Mechanisms Only Tell Half Story: Multiple Biological Processes are involved in Regulating Freezing Tolerance of Imbibed Lactuca sativa Seeds.

PubMed

Jaganathan, Ganesh K; Han, Yingying; Li, Weijie; Song, Danping; Song, Xiaoyan; Shen, Mengqi; Zhou, Qiang; Zhang, Chenxue; Liu, Baolin

2017-03-13

The physiological mechanisms by which imbibed seeds survive freezing temperatures in their natural environment have been categorized as freezing avoidance by supercooling and freezing tolerance by extracellular freeze-desiccation, but the biochemical and molecular mechanisms conferring seed freezing tolerance is unexplored. In this study, using imbibed Lactuca sativa seeds we show that fast cooled seeds (60 °C h -1 ) suffered significantly higher membrane damage at temperature between -20 °C and -10 °C than slow cooled (3 °Ch -1 ) seeds (P < 0.05), presumably explaining viability loss during fast cooling when temperature approaches -20 °C. Total soluble sugars increase in low temperature environment, but did not differ significantly between two cooling rates (P > 0.05). However, both SOD activity and accumulation of free proline were induced significantly after slow cooling to -20 °C compared with fast cooling. RNA-seq demonstrated that multiple pathways were differentially regulated between slow and fast cooling. Real-time verification of some differentially expressed genes (DEGs) revealed that fast cooling caused mRNA level changes of plant hormone and ubiquitionation pathways at higher sub-zero temperature, whilst slow cooling caused mRNA level change of those pathways at lower sub-zero ttemperatures. Thus, we conclude that imbibed seed tolerate low temperature not only by physiological mechanisms but also by biochemical and molecular changes.

Effect of water on the low temperature conductivity of polymer electrolytes.

PubMed

Siu, Ana; Schmeisser, Jennifer; Holdcroft, Steven

2006-03-30

The proton conductivity of radiation-grafted ethylenetetrafluoroethylene-grafted-poly(styrene sulfonic) acid (ETFE-g-PSSA) and Nafion 117 membranes between 25 and -37 degrees C is reported. The freezing of water in the membranes, which strongly depends on the internal acid concentration, results in a 4-fold decrease in proton conductivity. The activation energies before and after the freezing of the membranes are approximately 0.15 and 0.4 eV, consistent with proton transport through liquid water and strongly bound water, respectively. Differential scanning calorimetry data show that up to 14 H(2)O molecules per H(+)/SO(3)(-) group remain unfrozen at subzero temperatures and are believed to be responsible for the low temperature conductivity that is observed. These results indicate that proton conductivity in membranes may be achieved via strongly bound and highly polarized water.

The effect of undissolved air on isochoric freezing.

PubMed

Perez, Pedro A; Preciado, Jessica; Carlson, Gary; DeLonzor, Russ; Rubinsky, Boris

2016-06-01

This study evaluates the effect of undissolved air on isochoric freezing of aqueous solutions. Isochoric freezing is concerned with freezing in a constant volume thermodynamic system. A possible advantage of the process is that it substantially reduces the percentage of ice in the system at every subzero temperature, relative to atmospheric freezing. At the pressures generated by isochoric freezing, or high pressure isobaric freezing, air cannot be considered an incompressible substance and the presence of undissolved air substantially increases the amount of ice that forms at any subfreezing temperature. This effect is measurable at air volumes as low as 1%. Therefore eliminating the undissolved air, or any separate gaseous phase, from the system is essential for retaining the properties of isochoric freezing. Copyright © 2016. Published by Elsevier Inc.

Fundamental modeling the performance and degradation of HEV Lithium-ion battery

NASA Astrophysics Data System (ADS)

Fang, Weifang

Li-ion battery is now replacing nickel-metal hydride (NiMH) for hybrid electric vehicles (HEV). The advantages of Li-ion battery over NiMH are that it can provide longer life, higher cell voltage and higher energy density, etc. However, there are still some issues unsolved for Li-ion battery to fully satisfy the HEV requirement. At high temperature, thermal runaway may cause safety issues. At low temperature, however, its performance is dramatically reduced and also Li deposition may occur. Furthermore, degradation due to side reactions in the electrodes during cycling and storage results in capacity loss and impedance rise. An electrochemical-thermal coupled model is first used to predict performance of individual electrodes of Li-ion cells under HEV conditions that encompass a wide range of ambient temperatures. The model is validated against experimental data of not only the full cell but also individual electrodes and then used to study lithium deposition on the negative electrode during charging Li-ion battery at subzero temperature. The simulated property evolution, e.g. Li concentrations in electrode and electrolyte, shows that either low temperature or high charge rate may force Li insertion (into the negative carbon electrode) to occur in a narrow region near the separator. Therefore, Li deposition is mostly like to happen in this location. Modeling simulation shows that reduction of the negative electrode particle size can reduce Li deposition, which has same effect as improvement of the Li diffusion coefficient in the negative electrode. The model is also used to study charge protocols at subzero temperature. Model simulation shows that employing pulse current can improve cell temperature by the heat generated inside the cell, thus this designed charge protocol is able to reduce Li deposition and improve the charge efficiency as well. Individual aging mechanism is then implemented into each electrode to study Li-ion battery degradation during accelerated aging tests. The experimentally observed aging phenomena are interpreted using the degradation model. The simulated results show that the positive electrode active material loss is the main cause of capacity loss and impedance growth. And this is the key step for a model to well catch the experimentally observed aging phenomena in the two electrodes. In the future work, the degradation model will further help to prolong battery life through engineering and optimization in HEV applications.

The effect of low temperature on Antarctic endolithic green algae

NASA Technical Reports Server (NTRS)

Meyer, M. A.; Morris, G. J.; Friedmann, E. I.

1988-01-01

Laboratory experiments show that undercooling to about -5 degrees C occurs in colonized Beacon sandstones of the Ross Desert, Antarctica. High-frequency temperature oscillations between 5 degrees C and -5 degrees C or -10 degrees C (which occur in nature on the rock surface) did not damage Hemichloris antarctica. In a cryomicroscope, H. antarctica appeared to be undamaged after slow or rapid cooling to -50 degrees C. 14CO2 incorporation after freezing to -20 degrees C was unaffected in H. antarctica or in Trebouxia sp. but slightly depressed in Stichococcus sp. (isolated from a less extreme Antarctic habitat). These results suggest that the freezing regime in the Antarctic desert is not injurious to endolithic algae. It is likely that the freezing-point depression inside the rock makes available liquid water for metabolic activity at subzero temperatures. Freezing may occur more frequently on the rock surface and contribute to the abiotic nature of the surface.

Li + -Desolvation Dictating Lithium-Ion Battery’s Low-Temperature Performances

DOE PAGES

Li, Qiuyan; Lu, Dongping; Zheng, Jianming; ...

2017-11-17

Lithium (Li) ion battery (LIB) has penetrated almost every aspects of human life, from portable electronics, vehicles to grids, and its operation stability in extreme environments becomes increasingly important. Among these, sub-zero temperature presents a kinetic challenge to the electrochemical reactions required to deliver the stored energy. Here, in this work, we attempted to identify the rate-determining process for Li + migration under such low temperatures, so that an optimum electrolyte formulation could be designed to maximize the energy output. Substantial increase in available capacities from graphite||LiNi 0.80Co 0.15Al 0.05O 2 chemistry down to -40°C is achieved by reducing themore » solvent molecule that more tightly binds to Li + and thus constitutes high desolvation energy barrier. Lastly, the fundamental understanding is applicable universally to a wide spectrum of electrochemical devices that have to operate in similar environments.« less

Li+-Desolvation Dictating Lithium-Ion Battery's Low-Temperature Performances.

PubMed

Li, Qiuyan; Lu, Dongping; Zheng, Jianming; Jiao, Shuhong; Luo, Langli; Wang, Chong-Min; Xu, Kang; Zhang, Ji-Guang; Xu, Wu

2017-12-13

Lithium (Li) ion battery has penetrated almost every aspect of human life, from portable electronics, vehicles, to grids, and its operation stability in extreme environments is becoming increasingly important. Among these, subzero temperature presents a kinetic challenge to the electrochemical reactions required to deliver the stored energy. In this work, we attempted to identify the rate-determining process for Li + migration under such low temperatures, so that an optimum electrolyte formulation could be designed to maximize the energy output. Substantial increase in the available capacities from graphite∥LiNi 0.80 Co 0.15 Al 0.05 O 2 chemistry down to -40 °C is achieved by reducing the solvent molecule that more tightly binds to Li + and thus constitutes a high desolvation energy barrier. The fundamental understanding is applicable universally to a wide spectrum of electrochemical devices that have to operate in similar environments.

Li + -Desolvation Dictating Lithium-Ion Battery’s Low-Temperature Performances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Qiuyan; Lu, Dongping; Zheng, Jianming

Lithium (Li) ion battery (LIB) has penetrated almost every aspects of human life, from portable electronics, vehicles to grids, and its operation stability in extreme environments becomes increasingly important. Among these, sub-zero temperature presents a kinetic challenge to the electrochemical reactions required to deliver the stored energy. In this work, we attempted to identify the rate-determining process for Li+ migration under such low temperatures, so that an optimum electrolyte formulation could be designed to maximize the energy output. Substantial increase in available capacities from graphite||LiNi0.80Co0.15Al0.05O2 chemistry down to -40°C is achieved by reducing the solvent molecule that more tightly bindsmore » to Li+ and thus constitutes high desolvation energy barrier. The fundamental understanding is applicable universally to all electrochemical devices that have to operate in similar environments.« less

Li + -Desolvation Dictating Lithium-Ion Battery’s Low-Temperature Performances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Qiuyan; Lu, Dongping; Zheng, Jianming

Lithium (Li) ion battery (LIB) has penetrated almost every aspects of human life, from portable electronics, vehicles to grids, and its operation stability in extreme environments becomes increasingly important. Among these, sub-zero temperature presents a kinetic challenge to the electrochemical reactions required to deliver the stored energy. Here, in this work, we attempted to identify the rate-determining process for Li + migration under such low temperatures, so that an optimum electrolyte formulation could be designed to maximize the energy output. Substantial increase in available capacities from graphite||LiNi 0.80Co 0.15Al 0.05O 2 chemistry down to -40°C is achieved by reducing themore » solvent molecule that more tightly binds to Li + and thus constitutes high desolvation energy barrier. Lastly, the fundamental understanding is applicable universally to a wide spectrum of electrochemical devices that have to operate in similar environments.« less

Superelastic and pH-Responsive Degradable Dendrimer Cryogels Prepared by Cryo-aza-Michael Addition Reaction.

PubMed

Wang, Juan; Yang, Hu

2018-05-08

Dendrimers exhibit super atomistic features by virtue of their well-defined discrete quantized nanoscale structures. Here, we show that hyperbranched amine-terminated polyamidoamine (PAMAM) dendrimer G4.0 reacts with linear polyethylene glycol (PEG) diacrylate (575 g/mol) via the aza-Michael addition reaction at a subzero temperature (-20 °C), namely cryo-aza-Michael addition, to form a macroporous superelastic network, i.e., dendrimer cryogel. Dendrimer cryogels exhibit biologically relevant Young's modulus, high compression elasticity and super resilience at ambient temperature. Furthermore, the dendrimer cryogels exhibit excellent rebound performance and do not show significant stress relaxation under cyclic deformation over a wide temperature range (-80 to 100 °C). The obtained dendrimer cryogels are stable at acidic pH but degrade quickly at physiological pH through self-triggered degradation. Taken together, dendrimer cryogels represent a new class of scaffolds with properties suitable for biomedical applications.

An investigation into the impact of cryogenic environment on mechanical stresses in FRP composites

NASA Astrophysics Data System (ADS)

Fifo, O.; Basu, B.

2015-07-01

Fibre reinforced polymer (FRP) composites are fast becoming a highly utilised engineering material for high performance applications due to their light weight and high strength. Carbon fibre and other high strength fibres are commonly used in design of aerospace structures, wind turbine blades, etc. and potentially for propellant tanks of launch vehicles. For the aforementioned fields of application, stability of the material is essential over a wide range of temperature particularly for structures in hostile environments. Many studies have been conducted, experimentally, over the last decade to investigate the mechanical behaviour of FRP materials at varying subzero temperature. Likewise, tests on aging and cycling effect (room to low temperature) on the mechanical response of FRP have been reported. However, a relatively lesser focused area has been the mechanical behaviour of FRP composites under cryogenic environment. This article reports a finite element method of investigating the changes in the mechanical characteristics of an FRP material when temperature based analysis falls below zero. The simulated tests are carried out using a finite element package with close material properties used in the cited literatures. Tensile test was conducted and the results indicate that the mechanical responses agree with those reported in the literature sited.

Operational Lessons Learned in the Korean War

DTIC Science & Technology

2011-12-01

per response, including the time for reviewing instructions, searching existing data sources , gathering and maintaining the data needed, and...marines and soldiers faced sub-zero temperatures and heavy snowfall that blocked mountain passes and clogged main supply routes. Fifty years later...soldiers and airmen serving in Korea experienced another such harsh winter that limited operations because of heavy snowfall and had an impact their

How Circulation of Water Affects Freezing in Ponds

ERIC Educational Resources Information Center

Moreau, Theresa; Lamontagne, Robert; Letzring, Daniel

2007-01-01

One means of preventing the top of a pond from freezing involves running a circulating pump near the bottom to agitate the surface and expose it to air throughout the winter months. This phenomenon is similar to that of the flowing of streams in subzero temperatures and to the running of taps to prevent pipe bursts in winter. All of these cases…

Porphyrin-Based Symmetric Redox-Flow Batteries towards Cold-Climate Energy Storage.

PubMed

Ma, Ting; Pan, Zeng; Miao, Licheng; Chen, Chengcheng; Han, Mo; Shang, Zhenfeng; Chen, Jun

2018-03-12

Electrochemical energy storage with redox-flow batteries (RFBs) under subzero temperature is of great significance for the use of renewable energy in cold regions. However, RFBs are generally used above 10 °C. Herein we present non-aqueous organic RFBs based on 5,10,15,20-tetraphenylporphyrin (H 2 TPP) as a bipolar redox-active material (anode: [H 2 TPP] 2- /H 2 TPP, cathode: H 2 TPP/[H 2 TPP] 2+ ) and a Y-zeolite-poly(vinylidene fluoride) (Y-PVDF) ion-selective membrane with high ionic conductivity as a separator. The constructed RFBs exhibit a high volumetric capacity of 8.72 Ah L -1 with a high voltage of 2.83 V and excellent cycling stability (capacity retention exceeding 99.98 % per cycle) in the temperature range between 20 and -40 °C. Our study highlights principles for the design of RFBs that operate at low temperatures, thus offering a promising approach to electrochemical energy storage under cold-climate conditions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein cold adaptation strategy via a unique seven-amino acid domain in the icefish (Chionodraco hamatus) PEPT1 transporter

PubMed Central

Rizzello, Antonia; Romano, Alessandro; Kottra, Gabor; Acierno, Raffaele; Storelli, Carlo; Verri, Tiziano; Daniel, Hannelore; Maffia, Michele

2013-01-01

Adaptation of organisms to extreme environments requires proteins to work at thermodynamically unfavorable conditions. To adapt to subzero temperatures, proteins increase the flexibility of parts of, or even the whole, 3D structure to compensate for the lower thermal kinetic energy available at low temperatures. This may be achieved through single-site amino acid substitutions in regions of the protein that undergo large movements during the catalytic cycle, such as in enzymes or transporter proteins. Other strategies of cold adaptation involving changes in the primary amino acid sequence have not been documented yet. In Antarctic icefish (Chionodraco hamatus) peptide transporter 1 (PEPT1), the first transporter cloned from a vertebrate living at subzero temperatures, we came upon a unique principle of cold adaptation. A de novo domain composed of one to six repeats of seven amino acids (VDMSRKS), placed as an extra stretch in the cytosolic COOH-terminal region, contributed per se to cold adaptation. VDMSRKS was in a protein region uninvolved in transport activity and, notably, when transferred to the COOH terminus of a warm-adapted (rabbit) PEPT1, it conferred cold adaptation to the receiving protein. Overall, we provide a paradigm for protein cold adaptation that relies on insertion of a unique domain that confers greater affinity and maximal transport rates at low temperatures. Due to its ability to transfer a thermal trait, the VDMSRKS domain represents a useful tool for future cell biology or biotechnological applications. PMID:23569229

A carrot leucine-rich-repeat protein that inhibits ice recrystallization.

PubMed

Worrall, D; Elias, L; Ashford, D; Smallwood, M; Sidebottom, C; Lillford, P; Telford, J; Holt, C; Bowles, D

1998-10-02

Many organisms adapted to live at subzero temperatures express antifreeze proteins that improve their tolerance to freezing. Although structurally diverse, all antifreeze proteins interact with ice surfaces, depress the freezing temperature of aqueous solutions, and inhibit ice crystal growth. A protein purified from carrot shares these functional features with antifreeze proteins of fish. Expression of the carrot complementary DNA in tobacco resulted in the accumulation of antifreeze activity in the apoplast of plants grown at greenhouse temperatures. The sequence of carrot antifreeze protein is similar to that of polygalacturonase inhibitor proteins and contains leucine-rich repeats.

Ammonia volatilization from farm tanks containing anaerobically digested animal slurry

NASA Astrophysics Data System (ADS)

Sommer, S. G.

Ammonia (NH 3) volatilization from three full-scale tanks containing anaerobically digested animal slurry from one biogas plant was determined with a meteorological mass balance technique. No surface crust developed on the slurry. This provided an ideal system for analysing loss patterns from slurries without cover and to study the effect of a cover of straw and air-filled clay granules. Ammonia volatilization from uncovered slurry ranged from zero at subzero temperatures to 30 g N m -2 d -1 during summer. The high volatilization rate was attributed to a lack of surface cover, high slurry pH and high TAN (NH 3 + NH 4+) concentration. Ammonia volatilization from the covered slurry was insignificant. From the uncovered slurry the annual loss of NH3 was 3.3 kg N m -2 There was a significant effect of incident global radiation (ICR), air temperature at 20 cm (T_20) and rain on NH3 volatilization from the uncovered slurry. The straw covered slurry was significantly affected by T_20.

Pressure in isochoric systems containing aqueous solutions at subzero Centigrade temperatures.

PubMed

Ukpai, Gideon; Năstase, Gabriel; Șerban, Alexandru; Rubinsky, Boris

2017-01-01

Preservation of biological materials at subzero Centigrade temperatures, cryopreservation, is important for the field of tissue engineering and organ transplantation. Our group is studying the use of isochoric (constant volume) systems of aqueous solution for cryopreservation. Previous studies measured the pressure-temperature relations in aqueous isochoric systems in the temperature range from 0°C to - 20°C. The goal of this study is to expand the pressure-temperature measurement beyond the range reported in previous publications. To expand the pressure-temperature measurements beyond the previous range, we have developed a new isochoric device capable of withstanding liquid nitrogen temperatures and pressures of up to 413 MPa. The device is instrumented with a pressure transducer than can monitor and record the pressures in the isochoric chamber in real time. Measurements were made in a temperature range from - 5°C to liquid nitrogen temperatures for various solutions of pure water and Me2SO (a chemical additive used for protection of biological materials in a frozen state and for vitrification (glass formation) of biological matter). Undissolved gaseous are is carefully removed from the system. Temperature-pressure data from - 5°C to liquid nitrogen temperature for pure water and other solutions are presented in this study. Following are examples of some, temperature-pressure values, that were measured in an isochoric system containing pure water: (- 20°C, 187 MPa); (-25°C, 216 MPa); (- 30°C, 242.3 MPa); (-180°C, 124 MPa). The data is consistent with the literature, which reports that the pressure and temperature at the triple point, between ice I, ice III and water is, - 21.993°C and 209.9 MPa, respectively. It was surprising to find that the pressure in the isochoric system increases at temperatures below the triple point and remains high to liquid nitrogen temperatures. Measurements of pressure-temperature relations in solutions of pure water and Me2SO in different concentrations show that, for concentrations in which vitrification is predicted, no increase in pressure was measured during rapid cooling to liquid nitrogen temperatures. However, ice formation either during cooling or warming to and from liquid nitrogen temperatures produced an increase in pressure. The data obtained in this study can be used to aid in the design of isochoric cryopreservation protocols. The results suggest that the pressure measurement is important in the design of "constant volume" systems and can provide a simple means to gain information on the occurrence of vitrification and devitrification during cryopreservation processes of aqueous solutions in an isochoric system.

21 CFR 101.95 - “Fresh,” “freshly frozen,” “fresh frozen,” “frozen fresh.”

Code of Federal Regulations, 2010 CFR

2010-04-01

... fresh.â 101.95 Section 101.95 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... Descriptive Claims That Are Neither Nutrient Content Claims nor Health Claims § 101.95 “Fresh,” “freshly... frozen by a freezing system such as blast-freezing (sub-zero Fahrenheit temperature with fast moving air...

Permafrost Meta-Omics and Climate Change

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mackelprang, Rachel; Saleska, Scott R.; Jacobsen, Carsten Suhr

2016-06-29

Permafrost (i.e., soil that has been frozen for at least 2 consecutive years) represents a habitat for microbial life at subzero temperatures (Gilichinsky et al. 2008). Approximately one quarter of the Earth’s surface is underlain by permafrost, which contains 25-50% of the total global soil carbon pool (Schuur et al. 2008, Tarnocai et al. 2009). This carbon is largely protected from microbial decomposition by reduced microbial activity in frozen conditions, but climate change is threatening to induce large-scale permafrost thaw thus exposing it to degradation. The resulting emissions of greenhouse gasses (GHGs) can produce a positive feedback loop and significantlymore » amplify the effects of global warming. Increasing temperatures at high latitudes, changes in precipitation patterns, and frequent fire events have already initiated a widespread degradation of permafrost (Schuur et al. 2015).« less

Experimental investigations of an AC pulse heating method for vehicular high power lithium-ion batteries at subzero temperatures

NASA Astrophysics Data System (ADS)

Zhu, Jiangong; Sun, Zechang; Wei, Xuezhe; Dai, Haifeng; Gu, Weijun

2017-11-01

Effect of the AC (alternating current) pulse heating method on battery SoH (state of health) for large laminated power lithium-ion batteries at low temperature is investigated experimentally. Firstly, excitation current frequencies, amplitudes, and voltage limitations on cell temperature evolution are studied. High current amplitudes facilitate the heat accumulation and temperature rise. Low frequency region serves as a good innovation to heat the battery because of the large impedance. Wide voltage limitations also enjoy better temperature evolution owing to the less current modulation, but the temperature difference originated from various voltage limitations attenuates due to the decrement of impedance resulting from the temperature rise. Experiments with the thermocouple-embedded cell manifest good temperature homogeneity between the battery surface and interior during the AC heating process. Secondly, the cell capacity, Direct Current resistance and Electrochemical Impedance Spectroscopy are all calibrated to assess the battery SoH after the hundreds of AC pulse heating cycles. Also, all cells are disassembled to investigate the battery internal morphology with the employment of Scanning Electron Microscope and Energy-Dispersive x-ray Spectroscopy techniques. The results indicate that the AC heating method does not aggravate the cell degradation even in the low frequency range (0.5 Hz) under the normal voltage protection limitation.

Evidence of in situ microbial activity and sulphidogenesis in perennially sub-0 °C and hypersaline sediments of a high Arctic permafrost spring.

PubMed

Lamarche-Gagnon, Guillaume; Comery, Raven; Greer, Charles W; Whyte, Lyle G

2015-01-01

The lost hammer (LH) spring perennially discharges subzero hypersaline reducing brines through thick layers of permafrost and is the only known terrestrial methane seep in frozen settings on Earth. The present study aimed to identify active microbial communities that populate the sediments of the spring outlet, and verify whether such communities vary seasonally and spatially. Microcosm experiments revealed that the biological reduction of sulfur compounds (SR) with hydrogen (e.g., sulfate reduction) was potentially carried out under combined hypersaline and subzero conditions, down to -20 °C, the coldest temperature ever recorded for SR. Pyrosequencing analyses of both 16S rRNA (i.e., cDNA) and 16S rRNA genes (i.e., DNA) of sediments retrieved in late winter and summer indicated fairly stable bacterial and archaeal communities at the phylum level. Potentially active bacterial and archaeal communities were dominated by clades related to the T78 Chloroflexi group and Halobacteria species, respectively. The present study indicated that SR, hydrogenotrophy (possibly coupled to autotrophy), and short-chain alkane degradation (other than methane), most likely represent important, previously unaccounted for, metabolic processes carried out by LH microbial communities. Overall, the obtained findings provided additional evidence that the LH system hosts active communities of anaerobic, halophilic, and cryophilic microorganisms despite the extreme conditions in situ.

Cryoprotection in dampwood termites (Termopsidae, Isoptera).

PubMed

Lacey, Michael J; Lenz, Michael; Evans, Theodore A

2010-01-01

In contrast to the majority of the Order, the dampwood termites of the family Termopsidae found in colder regions can experience frost and snow, either in cool temperate areas at high latitudes (45 degrees ), or alpine areas at high elevations (>1000m). This suggests that dampwood termites are adapted to cold climates. We investigated this hypothesis in two dampwood termites, Porotermes adamsoni Froggatt and Stolotermes victoriensis Hill. We measured nest temperatures and atmospheric temperatures of their alpine habitat during winter, and measured survival and recovery at subzero temperatures. We also determined the minimum temperature at which these species remain active and the LT50 values. We used a novel gas chromatographic strategy to examine eight metabolites from individuals of both species collected in winter and summer to identify possible cryoprotectants. Both P. adamsoni and S. victoriensis had significantly higher levels of trehalose, a known cryoprotectant, in winter than in summer; in addition S. victoriensis also had higher levels of unsaturated fatty acid ligands in winter than in summer, consistent with patterns observed for cold adaptation in other organisms. These results are the first to reveal that dampwood termites are adapted to cold climates and use trehalose and unsaturated lipids as cryoprotectants.

Dynamics of water in sulfonated poly(phenylene) membranes

NASA Astrophysics Data System (ADS)

Osti, Naresh; Etampawala, Thusitha; Shrestha, Umesh; Perahia, Dvora; Cornelius, Christopher

2011-03-01

The dynamics of water in networks formed by highly rigid ionic polymers, sulfonated poly(phenylene) as observed by quasi elastic neutron scattering (QENS) is presented. These rigid ionic polymers have potential as effective ion exchange membranes with impact on a large number of applications from water purification to clean energy, where its rigidity distinguishes it from other ionic polymers. Its transport characteristics are affected by its rigidness as well as by direct interactions with the solvent. Our QENS studies as a function of sulfonation levels, temperature and solvent content have shown that on the time scale of the measurement, the polymers are rigid. While macroscopically all samples swell, and transport water, the water molecules appear locally rather confined. Water however remind non-frozen to subzero temperatures. The results will be discussed in view of theoretical models including continues diffusion and hopping of solvent molecules.

Cold machining of high density tungsten and other materials

NASA Technical Reports Server (NTRS)

Ziegelmeier, P.

1969-01-01

Cold machining process, which uses a sub-zero refrigerated cutting fluid, is used for machining refractory or reactive metals and alloys. Special carbide tools for turning and drilling these alloys further improve the cutting performance.

76 FR 72675 - Foreign-Trade Zone 277, Temporary/Interim Manufacturing Authority, Sub-Zero, Inc., (Refrigerators...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-25

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [Docket T-5-2011] Foreign-Trade Zone 277, Temporary/Interim Manufacturing Authority, Sub-Zero, Inc., (Refrigerators), Notice of Approval On October 3... manufacturing (T/IM) authority, on behalf of Sub- Zero, Inc., to manufacture refrigerators under FTZ procedures...

Pressure in isochoric systems containing aqueous solutions at subzero Centigrade temperatures

PubMed Central

Șerban, Alexandru; Rubinsky, Boris

2017-01-01

Objective Preservation of biological materials at subzero Centigrade temperatures, cryopreservation, is important for the field of tissue engineering and organ transplantation. Our group is studying the use of isochoric (constant volume) systems of aqueous solution for cryopreservation. Previous studies measured the pressure-temperature relations in aqueous isochoric systems in the temperature range from 0°C to – 20°C. The goal of this study is to expand the pressure-temperature measurement beyond the range reported in previous publications. Materials and methods To expand the pressure-temperature measurements beyond the previous range, we have developed a new isochoric device capable of withstanding liquid nitrogen temperatures and pressures of up to 413 MPa. The device is instrumented with a pressure transducer than can monitor and record the pressures in the isochoric chamber in real time. Measurements were made in a temperature range from – 5°C to liquid nitrogen temperatures for various solutions of pure water and Me2SO (a chemical additive used for protection of biological materials in a frozen state and for vitrification (glass formation) of biological matter). Undissolved gaseous are is carefully removed from the system. Results Temperature-pressure data from – 5°C to liquid nitrogen temperature for pure water and other solutions are presented in this study. Following are examples of some, temperature-pressure values, that were measured in an isochoric system containing pure water: (- 20°C, 187 MPa); (-25°C, 216 MPa); (- 30°C, 242.3 MPa); (-180°C, 124 MPa). The data is consistent with the literature, which reports that the pressure and temperature at the triple point, between ice I, ice III and water is, - 21.993°C and 209.9 MPa, respectively. It was surprising to find that the pressure in the isochoric system increases at temperatures below the triple point and remains high to liquid nitrogen temperatures. Measurements of pressure-temperature relations in solutions of pure water and Me2SO in different concentrations show that, for concentrations in which vitrification is predicted, no increase in pressure was measured during rapid cooling to liquid nitrogen temperatures. However, ice formation either during cooling or warming to and from liquid nitrogen temperatures produced an increase in pressure. Conclusions The data obtained in this study can be used to aid in the design of isochoric cryopreservation protocols. The results suggest that the pressure measurement is important in the design of “constant volume” systems and can provide a simple means to gain information on the occurrence of vitrification and devitrification during cryopreservation processes of aqueous solutions in an isochoric system. PMID:28817681

Translational diffusion coefficients of volatile compounds in various aqueous solutions at low and subzero temperatures.

PubMed

Covarrubias-Cervantes, Marco; Champion, Dominique; Debeaufort, Frédéric; Voilley, Andrée

2005-08-24

Translational diffusion coefficients (D(12)) of volatile compounds were measured in model media with the profile concentration method. The influence of sample temperature (from 25 to -10 degrees C) was studied on translational diffusion in sucrose or maltodextrin solutions at various concentrations. Results show that diffusivity of volatile compounds in sucrose solutions is controlled by temperature, molecule size, and the viscosity of the liquid phase as expected with the Stokes-Einstein equation; moreover, physicochemical interactions between volatile compounds and the medium are determinant for diffusion estimation. At negative temperature, the winding path induced by an ice crystal content of >70% lowered volatile compound diffusion. On the contrary, no influence on translational diffusion coefficients was observed for lower ice content.

Water dynamics in rigid ionomer networks.

PubMed

Osti, N C; Etampawala, T N; Shrestha, U M; Aryal, D; Tyagi, M; Diallo, S O; Mamontov, E; Cornelius, C J; Perahia, D

2016-12-14

The dynamics of water within ionic polymer networks formed by sulfonated poly(phenylene) (SPP), as revealed by quasi-elastic neutron scattering (QENS), is presented. These polymers are distinguished from other ionic macromolecules by their rigidity and therefore in their network structure. QENS measurements as a function of temperature as the fraction of ionic groups and humidity were varied have shown that the polymer molecules are immobile while absorbed water molecules remain dynamic. The water molecules occupy multiple sites, either bound or loosely constrained, and bounce between the two. With increasing temperature and hydration levels, the system becomes more dynamic. Water molecules remain mobile even at subzero temperatures, illustrating the applicability of the SPP membrane for selective transport over a broad temperature range.

Computational design and refinement of self-heating lithium ion batteries

NASA Astrophysics Data System (ADS)

Yang, Xiao-Guang; Zhang, Guangsheng; Wang, Chao-Yang

2016-10-01

The recently discovered self-heating lithium ion battery has shown rapid self-heating from subzero temperatures and superior power thereafter, delivering a practical solution to poor battery performance at low temperatures. Here, we describe and validate an electrochemical-thermal coupled model developed specifically for computational design and improvement of the self-heating Li-ion battery (SHLB) where nickel foils are embedded in its structure. Predicting internal cell characteristics, such as current, temperature and Li-concentration distributions, the model is used to discover key design factors affecting the time and energy needed for self-heating and to explore advanced cell designs with the highest self-heating efficiency. It is found that ohmic heat generated in the nickel foil accounts for the majority of internal heat generation, resulting in a large internal temperature gradient from the nickel foil toward the outer cell surface. The large through-plane temperature gradient leads to highly non-uniform current distribution, and more importantly, is found to be the decisive factor affecting the heating time and energy consumption. A multi-sheet cell design is thus proposed and demonstrated to substantially minimize the temperature gradient, achieving 30% more rapid self-heating with 27% less energy consumption than those reported in the literature.

TOPICAL REVIEW: Protein stability and enzyme activity at extreme biological temperatures

NASA Astrophysics Data System (ADS)

Feller, Georges

2010-08-01

Psychrophilic microorganisms thrive in permanently cold environments, even at subzero temperatures. To maintain metabolic rates compatible with sustained life, they have improved the dynamics of their protein structures, thereby enabling appropriate molecular motions required for biological activity at low temperatures. As a consequence of this structural flexibility, psychrophilic proteins are unstable and heat-labile. In the upper range of biological temperatures, thermophiles and hyperthermophiles grow at temperatures > 100 °C and synthesize ultra-stable proteins. However, thermophilic enzymes are nearly inactive at room temperature as a result of their compactness and rigidity. At the molecular level, both types of extremophilic proteins have adapted the same structural factors, but in opposite directions, to address either activity at low temperatures or stability in hot environments. A model based on folding funnels is proposed accounting for the stability-activity relationships in extremophilic proteins.

Behavioural adaptations of Rana temporaria to cold climates.

PubMed

Ludwig, Gerda; Sinsch, Ulrich; Pelster, Bernd

2015-01-01

Environmental conditions at the edge of a species' ecological optimum can exert great ecological or evolutionary pressure at local populations. For ectotherms like amphibians temperature is one of the most important abiotic factors of their environment as it influences directly their metabolism and sets limits to their distribution. Amphibians have evolved three ways to cope with sub-zero temperatures: freeze tolerance, freeze protection, freeze avoidance. The aim of this study was to assess which strategy common frogs at mid and high elevation use to survive and thrive in cold climates. In particular we (1) tested for the presence of physiological freeze protection, (2) evaluated autumnal activity and overwintering behaviour with respect to freeze avoidance and (3) assessed the importance of different high-elevation microhabitats for behavioural thermoregulation. Common frogs did not exhibit any signs of freeze protection when experiencing temperatures around 0 °C. Instead they retreated to open water for protection and overwintering. High elevation common frogs remained active for around the same period of time than their conspecifics at lower elevation. Our results suggest that at mid and high elevation common frogs use freeze avoidance alone to survive temperatures below 0 °C. The availability of warm microhabitats, such as rock or pasture, provides high elevation frogs with the opportunity of behavioural thermoregulation and thus allows them to remain active at temperatures at which common frogs at lower elevation cease activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

MANIFESTATIONS OF INJURY IN YEAST CELLS EXPOSED TO SUBZERO TEMPERATURES II.

PubMed Central

Mazur, Peter

1961-01-01

Mazur, Peter (Oak Ridge National Laboratory, Oak Ridge, Tenn.). Manifestations of injury in yeast cells exposed to subzero temperatures. II. Changes in specific gravity and in the concentration and quantity of cell solids. J. Bacteriol. 82:673–684. 1961.—It has previously been established that subjecting cells of Saccharomyces cerevisiae to rapid cooling to −30 C results in cell death and in certain morphological alterations. The alterations consisted of the loss of the central vacuole and a 50% decrease in volume. The present experiments were concerned with determining whether the volume decrease was the result of the loss of water alone or of water plus cellular solutes. The density of the “frozenthawed” cells was found to increase from 1.14 to 1.25 g/cm3 on the basis of measurements of the sedimentation rate of the cells. Interferometric and refractometric measurements indicated, furthermore, that the concentration of cell solids increased from 20 to 28%, whereas the total mass of cell solids decreased from 25 to 17 μμg/cell. The decrease in cell volume was thus shown to be the result of loss of solution from the cells, a solution containing 11 to 16% solids. Measurements of the rate of dialysis suggested that most or all of these solids had a molecular weight below 600. The findings are consistent with the view that low-temperature exposure destroyed the vacuolar membrane and sufficiently damaged the permeability barriers of the cell to permit escape of low molecular weight compounds. The damage was present a few seconds after thawing, and may, therefore, have been a direct result of intracellular ice crystals which, on the basis of previous studies, are believed to be responsible for death from low-temperature exposure. PMID:14471819

Conventional freezing plus high pressure-low temperature treatment: Physical properties, microbial quality and storage stability of beef meat.

PubMed

Fernández, Pedro P; Sanz, Pedro D; Molina-García, Antonio D; Otero, Laura; Guignon, Bérengère; Vaudagna, Sergio R

2007-12-01

Meat high-hydrostatic pressure treatment causes severe decolouration, preventing its commercialisation due to consumer rejection. Novel procedures involving product freezing plus low-temperature pressure processing are here investigated. Room temperature (20°C) pressurisation (650MPa/10min) and air blast freezing (-30°C) are compared to air blast freezing plus high pressure at subzero temperature (-35°C) in terms of drip loss, expressible moisture, shear force, colour, microbial quality and storage stability of fresh and salt-added beef samples (Longissimus dorsi muscle). The latter treatment induced solid water transitions among ice phases. Fresh beef high pressure treatment (650MPa/20°C/10min) increased significantly expressible moisture while it decreased in pressurised (650MPa/-35°C/10min) frozen beef. Salt addition reduced high pressure-induced water loss. Treatments studied did not change fresh or salt-added samples shear force. Frozen beef pressurised at low temperature showed L, a and b values after thawing close to fresh samples. However, these samples in frozen state, presented chromatic parameters similar to unfrozen beef pressurised at room temperature. Apparently, freezing protects meat against pressure colour deterioration, fresh colour being recovered after thawing. High pressure processing (20°C or -35°C) was very effective reducing aerobic total (2-log(10) cycles) and lactic acid bacteria counts (2.4-log(10) cycles), in fresh and salt-added samples. Frozen+pressurised beef stored at -18°C during 45 days recovered its original colour after thawing, similarly to just-treated samples while their counts remain below detection limits during storage.

78 FR 35899 - Decision and Order Granting a Waiver to Samsung From the Department of Energy Residential...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-14

... acknowledged that its products are different from the ones addressed by the Sub-Zero waiver in that they... waiver was submitted contains one or more design characteristics that prevent testing according to the... its petition that DOE has already granted Sub-Zero a similar waiver pertaining to the use of dual...

A Novel Approach Toward Fabrication of High Performance Thin Film Composite Polyamide Membranes.

PubMed

Khorshidi, Behnam; Thundat, Thomas; Fleck, Brian A; Sadrzadeh, Mohtada

2016-02-29

A practical method is reported to enhance water permeability of thin film composite (TFC) polyamide (PA) membranes by decreasing the thickness of the selective PA layer. The composite membranes were prepared by interfacial polymerization (IP) reaction between meta-phenylene diamine (MPD)-aqueous and trimesoyl chloride (TMC)-organic solvents at the surface of polyethersulfone (PES) microporous support. Several PA TFC membranes were prepared at different temperatures of the organic solution ranging from -20 °C to 50 °C. The physico-chemical and morphological properties of the synthesized membranes were carefully characterized using serval analytical techniques. The results confirmed that the TFC membranes, synthesized at sub-zero temperatures of organic solution, had thinner and smoother PA layer with a greater degree of cross-linking and wettability compared to the PA films prepared at 50 °C. We demonstrated that reducing the temperature of organic solution effectively decreased the thickness of the PA active layer and thus enhanced water permeation through the membranes. The most water permeable membrane was prepared at -20 °C and exhibited nine times higher water flux compared to the membrane synthesized at room temperature. The method proposed in this report can be effectively applied for energy- and cost-efficient development of high performance nanofiltration and reverse osmosis membranes.

Effect of Bainitic Microstructure on Ballistic Performance of Armour Steel Weld Metal Using Developed High Ni-Coated Electrode

NASA Astrophysics Data System (ADS)

Pramanick, A. K.; Das, H.; Reddy, G. M.; Ghosh, M.; Nandy, S.; Pal, T. K.

2018-05-01

Welding of armour steel has gained significant importance during the past few years as recent civilian and military requirements demand weld metal properties matching with base metal having good ballistic performance along with high strength and toughness at - 40 °C as per specification. The challenge of armour steel welding therefore lies in controlling the weld metal composition which is strongly dependent on welding electrode/consumables, resulting in desired weld microstructure consisting of lower bainite along with retained austenite. The performance of butt-welded armour steel joints produced by the developed electrodes was evaluated using tensile testing, ballistic testing, impact toughness at room temperature and subzero temperature. Microstructures of weld metals are exclusively characterized by x-ray diffraction technique, scanning electron microscope and transmission electron microscopy with selected area diffraction pattern. Experimental results show that weld metal with relatively lower carbon, higher manganese and lower nickel content was attributed to lower bainite with film type of retained austenite may be considered as a most covetable microstructure for armour steel weld metal.

Effect of Bainitic Microstructure on Ballistic Performance of Armour Steel Weld Metal Using Developed High Ni-Coated Electrode

NASA Astrophysics Data System (ADS)

Pramanick, A. K.; Das, H.; Reddy, G. M.; Ghosh, M.; Nandy, S.; Pal, T. K.

2018-04-01

Welding of armour steel has gained significant importance during the past few years as recent civilian and military requirements demand weld metal properties matching with base metal having good ballistic performance along with high strength and toughness at - 40 °C as per specification. The challenge of armour steel welding therefore lies in controlling the weld metal composition which is strongly dependent on welding electrode/consumables, resulting in desired weld microstructure consisting of lower bainite along with retained austenite. The performance of butt-welded armour steel joints produced by the developed electrodes was evaluated using tensile testing, ballistic testing, impact toughness at room temperature and subzero temperature. Microstructures of weld metals are exclusively characterized by x-ray diffraction technique, scanning electron microscope and transmission electron microscopy with selected area diffraction pattern. Experimental results show that weld metal with relatively lower carbon, higher manganese and lower nickel content was attributed to lower bainite with film type of retained austenite may be considered as a most covetable microstructure for armour steel weld metal.

Comparative study of carbon free and carbon containing Li4Ti5O12 electrodes

NASA Astrophysics Data System (ADS)

Pohjalainen, Elina; Kallioinen, Jani; Kallio, Tanja

2015-04-01

Traditionally electrodes for lithium ion batteries are manufactured using carbon additives to increase the conductivity. However, in case of lithium titanate, Li4Ti5O12 (LTO), carbon free electrodes have gathered some interest lately. Therefore two LTO materials synthesized using the same synthesis but different end milling process resulting in materials with different particle size and surface area are compared here using electrodes manufactured with and without carbon additives. Both LTO samples (LTO-SP with small primary particle size and high surface area, and LTO-LP with larger primary particle size and small surface area) produce similar capacities and voltages with or without carbon additives at low C-rates at the room temperature. However, at high C-rates and/or sub-zero temperatures electrodes with carbon additives produce higher capacities and smaller ohmic losses and this behavior is more pronounced for the LTO electrodes with smaller primary particle size and larger surface area. These results show that the feasibility of carbon free LTO electrodes depends on the properties of LTO affecting the morphology of the electrode and consequently, the transport properties. This is most pronounced under conditions where electron and Li+ ion transfer become limiting (high C-rates and low temperature).

Ice-binding proteins: a remarkable diversity of structures for stopping and starting ice growth.

PubMed

Davies, Peter L

2014-11-01

Antifreeze proteins (AFPs) were discovered in marine fishes that need protection from freezing. These ice-binding proteins (IBPs) are widespread across biological kingdoms, and their functions include freeze tolerance and ice adhesion. Consistent with recent independent evolution, AFPs have remarkably diverse folds that rely heavily on hydrogen- and disulfide-bonding. AFP ice-binding sites are typically flat, extensive, relatively hydrophobic, and are thought to organize water into an ice-like arrangement that merges and freezes with the quasi-liquid layer next to the ice lattice. In this article, the roles, properties, and structure-function interactions of IBPs are reviewed, and their relationship to ice nucleation proteins, which promote freezing at high subzero temperatures, is explored. Copyright © 2014 Elsevier Ltd. All rights reserved.

Aroma volatility from aqueous sucrose solutions at low and subzero temperatures.

PubMed

Covarrubias-Cervantes, Marco; Champion, Dominique; Debeaufort, Frédéric; Voilley, Andrée

2004-11-17

The gas-liquid partition coefficients of ethyl acetate and ethyl hexanoate have been measured in water and aqueous sucrose solutions from 25 to -10 degrees C by dynamic headspace. Experiments were carried out on sucrose solutions at temperatures where no ice formation was possible. Results showed that when sucrose concentration increased, aroma volatility increased except for ethyl hexanoate and in the highest sucrose concentration solution (57.5%). A quasi-linear temperature decrease on aroma volatility was observed in sucrose solutions from 25 to around 4 and 0 degrees C. Then, from 0 to -10 degrees C, aroma volatility did not decrease: ethyl acetate volatility remained constant but that of ethyl hexanoate increased. Enthalpy of vaporization and activity coefficients of the aroma compounds were calculated.

Chlorophyll fluorescence emission as a reporter on cold tolerance in Arabidopsis thaliana accessions

PubMed Central

Mishra, Anamika; Höermiller, Imke I; Heyer, Arnd G; Nedbal, Ladislav

2011-01-01

Non-invasive, high-throughput screening methods are valuable tools in breeding for abiotic stress tolerance in plants. Optical signals such as chlorophyll fluorescence emission can be instrumental in developing new screening techniques. In order to examine the potential of chlorophyll fluorescence to reveal plant tolerance to low temperatures, we used a collection of nine Arabidopsis thaliana accessions and compared their fluorescence features with cold tolerance quantified by the well established electrolyte leakage method on detached leaves. We found that, during progressive cooling, the minimal chlorophyll fluorescence emission rose strongly and that this rise was highly dependent on the cold tolerance of the accessions. Maximum quantum yield of PSII photochemistry and steady state fluorescence normalized to minimal fluorescence were also highly correlated to the cold tolerance measured by the electrolyte leakage method. In order to further increase the capacity of the fluorescence detection to reveal the low temperature tolerance, we applied combinatorial imaging that employs plant classification based on multiple fluorescence features. We found that this method, by including the resolving power of several fluorescence features, can be well employed to detect cold tolerance already at mild sub-zero temperatures. Therefore, there is no need to freeze the screened plants to the largely damaging temperatures of around −15°C. This, together with the method's easy applicability, represents a major advantage of the fluorescence technique over the conventional electrolyte leakage method. PMID:21427532

Kinetics of ikaite precipitation and dissolution in seawater-derived brines at sub-zero temperatures to 265 K

NASA Astrophysics Data System (ADS)

Papadimitriou, Stathys; Kennedy, Hilary; Kennedy, Paul; Thomas, David N.

2014-09-01

The kinetics of calcium carbonate hexahydrate (ikaite) precipitation and dissolution were investigated in seawater and seawater-derived brines at sub-zero temperatures using the constant addition experimental technique. The steady state rate of these two processes was found to be a function of the deviation of the solution from equilibrium with respect to ikaite and conformed to the same empirical rate law as the anhydrous CaCO3 polymorphs, calcite and aragonite. In addition to the saturation state of the brine with respect to ikaite, the salinity of the brine and the temperature of the reaction evidently exerted some control on the ikaite precipitation kinetics, while the dissolution kinetics of the polymorph were not noticeably influenced by these two parameters. The experimental salinity and temperature conditions were equivalent to those at thermal equilibrium between brine and ice in the sea ice cover of polar seas. Simple modelling of the CO2 system by extrapolation of the oceanic equivalent to sea ice brines showed that the physical concentration of seawater ions and the changes in ikaite solubility as a function of salinity and temperature, both inherent in the sea ice system, would be insufficient to drive the emergent brines to ikaite supersaturation and precipitation in sea ice down to -8 °C. The loss of dissolved inorganic carbon to the gas phase of sea ice and to sympagic autotrophs are two independent mechanisms which, in nature, could prompt the brine CO2 system towards ikaite supersaturation and precipitation. Under these conditions, the steady state precipitation rate of ikaite was found to be fast enough for rapid formation within short time scales (days to weeks) in sea ice. The observed ikaite dissolution kinetics were also found conducive to short turn-over time scales of a few hours to a few days in corrosive solutions, such as surface seawater.

Cold-hearted bats: uncoupling of heart rate and metabolism during torpor at sub-zero temperatures.

PubMed

Currie, Shannon E; Stawski, Clare; Geiser, Fritz

2018-01-04

Many hibernating animals thermoregulate during torpor and defend their body temperature ( T b ) near 0°C by an increase in metabolic rate. Above a critical temperature ( T crit ), animals usually thermoconform. We investigated the physiological responses above and below T crit for a small tree-dwelling bat ( Chalinolobus gouldii , ∼14 g) that is often exposed to sub-zero temperatures during winter. Through simultaneous measurement of heart rate ( f H ) and oxygen consumption ( V̇ O 2 ), we show that the relationship between oxygen transport and cardiac function is substantially altered in thermoregulating torpid bats between 1 and -2°C, compared with thermoconforming torpid bats at mild ambient temperatures ( T a 5-20°C). T crit for this species was at a T a of 0.7±0.4°C, with a corresponding T b of 1.8±1.2°C. Below T crit , animals began to thermoregulate, as indicated by a considerable but disproportionate increase in both f H and V̇ O 2 The maximum increase in f H was only 4-fold greater than the average thermoconforming minimum, compared with a 46-fold increase in V̇ O 2 The differential response of f H and V̇ O 2  to low T a was reflected in a 15-fold increase in oxygen delivery per heart beat (cardiac oxygen pulse). During torpor at low T a , thermoregulating bats maintained a relatively slow f H and compensated for increased metabolic demands by significantly increasing stroke volume and tissue oxygen extraction. Our study provides new information on the relationship between metabolism and f H in an unstudied physiological state that may occur frequently in the wild and can be extremely costly for heterothermic animals. © 2018. Published by The Company of Biologists Ltd.

Intrusion of Subarctic Currents into a Perpetual Sub-zero Cold Pool Allows Recruitment and Export of Snow Crabs in the Northern Bering Sea

NASA Astrophysics Data System (ADS)

Kolts, J. M.; Lovvorn, J. R.; North, C. A.; Janout, M. A.

2016-02-01

Snow crabs (Chionoecetes opilio) are quite productive at suitable temperatures, but can also be abundant in water cold enough to depress settlement of larvae, growth, and reproduction. In much of the northern Bering Sea, bottom water temperatures are <-1°C for most or all of the year. Crab pelagic larvae prefer to settle at temperatures >0°C, so we found high densities of juveniles only where intruding warm currents deposited larvae in localized areas. After settlement, maturing crabs appeared to exhibit ontogenetic migration toward deeper, warmer water. Cold temperatures excluded key predators, but decreased fecundity by restricting females to small body size (with associated small clutches) and to breeding every 2 years. Migration to warmer water may allow females to breed annually, and to encounter more adult males needed to fertilize subsequent clutches. Because older males also emigrate, remaining adolescent males probably inseminate newly maturing females. Without localized intrusion of warmer currents, snow crabs might not persist at high densities in such cold waters. However, they are currently very abundant there, and export many pelagic larvae and adults. In this region of Arctic temperatures, the combination of localized intrusion of warm, Subarctic currents and ontogenetic migration toward warmer Subarctic waters allows this area to contribute importantly to adult crab populations in adjacent areas.

Patterns of variation in glycogen, free glucose and lactate in organs of supercooled hatchling painted turtles (Chrysemys picta).

PubMed

Packard, Mary J; Packard, Gary C

2005-08-01

Hatchling painted turtles (Chrysemys picta) typically spend their first winter of life in a shallow, subterranean hibernaculum (the natal nest), where they may be exposed for extended periods to ice and cold. The key to their survival seems to be to avoid freezing and to sustain a state of supercooling. As temperature declines below 0 degrees C, however, the heart of an unfrozen turtle beats progressively slower, the diminished perfusion of peripheral tissues with blood induces a functional hypoxia, and anaerobic glycolysis assumes ever greater importance as a source of ATP. We hypothesized that diminished circulatory function in supercooled turtles also reduces the delivery of metabolic substrates to peripheral tissues from central stores in the liver, so that the tissues depend increasingly on endogenous stores to fuel their metabolism. We discovered in the current investigation that part of the glycogen reserve in hearts and brains of hatchlings is mobilized during the first 10 days of exposure to -6 degrees C but that glucose from hepatic glycogen supports metabolism of the organs thereafter. Hatchlings that were held at -6 degrees C for 10 days and then at +3 degrees C for another 10 days were able to reconstitute some of the reserve of glycogen in heart and liver but not the glycogen reserve in brain. Patterns of accumulation of lactate in individual organs were very similar to those reported for whole animals in a companion study, and point to a high degree of reliance on anaerobic metabolism at -6 degrees C and to a lesser degree of reliance on anaerobiosis at higher subzero temperatures. Lactate had returned to baseline levels in organs of animals that were held for 10 days at -6 degrees C and for another 10 days at +3 degrees C, but free glucose remained elevated. Indeed, carbohydrate metabolism probably does not return to the pre-exposure state in any of the major organs until well after the exposure to subzero temperatures has ended, circulatory sufficiency has been restored, and aerobic respiration has fully supplanted anaerobic respiration as a source of ATP.

Cold Tolerance of the Male Gametophyte during Germination and Tube Growth Depends on the Flowering Time

PubMed Central

Wagner, Johanna; Gastl, Evelyn; Kogler, Martin; Scheiber, Michaela

2016-01-01

In temperate climates, most plants flower during the warmer season of the year to avoid negative effects of low temperatures on reproduction. Nevertheless, few species bloom in midwinter and early spring despite severe and frequent frosts at that time. This raises the question of adaption of sensible progamic processes such as pollen germination and pollen tube growth to low temperatures. The performance of the male gametophyte of 12 herbaceous lowland species flowering in different seasons was examined in vitro at different test temperatures using an easy to handle testing system. Additionally, the capacity to recover after the exposure to cold was checked. We found a clear relationship between cold tolerance of the activated male gametophyte and the flowering time. In most summer-flowering species, pollen germination stopped between 1 and 5 °C, whereas pollen of winter and early spring flowering species germinated even at temperatures below zero. Furthermore, germinating pollen was exceptionally frost tolerant in cold adapted plants, but suffered irreversible damage already from mild sub-zero temperatures in summer-flowering species. In conclusion, male gametophytes show a high adaptation potential to cold which might exceed that of female tissues. For an overall assessment of temperature limits for sexual reproduction it is therefore important to consider female functions as well. PMID:28036058

A Leech Capable of Surviving Exposure to Extremely Low Temperatures

PubMed Central

Suzuki, Dai; Miyamoto, Tomoko; Kikawada, Takahiro; Watanabe, Manabu; Suzuki, Toru

2014-01-01

It is widely considered that most organisms cannot survive prolonged exposure to temperatures below 0°C, primarily because of the damage caused by the water in cells as it freezes. However, some organisms are capable of surviving extreme variations in environmental conditions. In the case of temperature, the ability to survive subzero temperatures is referred to as cryobiosis. We show that the ozobranchid leech, Ozobranchus jantseanus, a parasite of freshwater turtles, has a surprisingly high tolerance to freezing and thawing. This finding is particularly interesting because the leach can survive these temperatures without any acclimation period or pretreatment. Specifically, the leech survived exposure to super-low temperatures by storage in liquid nitrogen (−196°C) for 24 hours, as well as long-term storage at temperatures as low as −90°C for up to 32 months. The leech was also capable of enduring repeated freeze-thaw cycles in the temperature range 20°C to −100°C and then back to 20°C. The results demonstrated that the novel cryotolerance mechanisms employed by O. jantseanus enable the leech to withstand a wider range of temperatures than those reported previously for cryobiotic organisms. We anticipate that the mechanism for the observed tolerance to freezing and thawing in O. jantseanus will prove useful for future studies of cryopreservation. PMID:24466250

Kinetics of Water Loss from Cells at Subzero Temperatures and the Likelihood of Intracellular Freezing

PubMed Central

Mazur, Peter

1963-01-01

The survival of various cells subjected to low temperature exposure is higher when they are cooled slowly. This increase is consistent with the view that slow cooling decreases the probability of intracellular freezing by permitting water to leave the cell rapidly enough to keep the protoplasm at its freezing point. The present study derives a quantitative relation between the amount of water in a cell and temperature. The relation is a differential equation involving cooling rate, surface-volume ratio, membrane permeability to water, and the temperature coefficient of the permeability constant. Numerical solutions to this equation give calculated water contents which permit predictions as to the likelihood of intracellular ice formation. Both the calculated water contents and the predictions on internal freezing are consistent with the experimental observations of several investigators. PMID:14085017

Physical-Chemical Basis of the Protection of Slowly Frozen Human Erythrocytes by Glycerol

PubMed Central

Rall, W. F.; Mazur, Peter; Souzu, Hiroshi

1978-01-01

One theory of freezing damage suggests that slowly cooled cells are killed by being exposed to increasing concentrations of electrolytes as the suspending medium freezes. A corollary to this view is that protective additives such as glycerol protect cells by acting colligatively to reduce the electrolyte concentration at any subzero temperature. Recently published phase-diagram data for the ternary system glycerol-NaCl-water by M. L. Shepard et al. (Cryobiology, 13:9-23, 1976), in combination with the data on human red cell survival vs. subzero temperature presented here and in the companion study of Souzu and Mazur (Biophys. J., 23:89-100), permit a precise test of this theory. Appropriate liquidus phase-diagram information for the solutions used in the red cell freezing experiments was obtained by interpolation of the liquidus data of Shepard and his co-workers. The results of phase-diagram analysis of red cell survival indicate that the correlation between the temperature that yields 50% hemolysis (LT50) and the electrolyte concentration attained at that temperature in various concentrations of glycerol is poor. With increasing concentrations of glycerol, the cells were killed at progressively lower concentrations of NaCl. For example, the LT50 for cells frozen in the absence of glycerol corresponds to a NaCl concentration of 12 weight percent (2.4 molal), while for cells frozen in 1.75 M glycerol in buffered saline the LT50 corresponds to 3.0 weight percent NaCl (1.3 molal). The data, in combination with other findings, lead to two conclusions: (a) The protection from glycerol is due to its colligative ability to reduce the concentration of sodium chloride in the external medium, but (b) the protection is less than that expected from colligative effects; apparently glycerol itself can also be a source of damage, probably because it renders the red cells susceptible to osmotic shock during thawing. PMID:667300

Influence of cryogenic treatment on microstructure and mechanical properties of high strength AISI D2 tool steel =

NASA Astrophysics Data System (ADS)

Ghasemi Nanesa, Hadi

Cryogenic treatment, known as treating materials at sub-zero temperatures, has been added to conventional heat treatment cycle of high alloyed steels where martensitic transformation is incomplete after quenching to room temperature. Incomplete martensitic transformation occurs due to the effect of high content of alloying elements on pushing down martensite start and finish temperatures to very low values, specifically, on tool steels. In spite of obtaining significant improvements in mechanical and wear properties after cryogenic treatment, there is no cohesive picture about what exactly modifies the microstructure of tool steels during cryogenic treatment and therefore divergent opinions on the influence of process parameters are still reported. For example, the suggested time length for cryogenic treatment starts from few seconds to several days indicating the lack of understanding about micromechanisms responsible for microstructural evolution while holding at cryogenic temperatures. In this regard, the main objective of this project is to develop a better understanding on the fundamental micromechanisms operating during cryogenic treatment. To attain this objective, the following milestones are pursued. - To study the conventional cryogenic treatment and finding challenges. - To identify and characterize the optimum starting microstructure before cryogenic treatment. - To determine the important processing parameters those control the evolution of microstructure and hardness. - To investigate the interaction between carbide precipitation and martensitic transformation in the AISI D2 steel. - To propose an optimal cryogenic treatment for AISI D2 steel.

Bacterial Activity at −2 to −20°C in Arctic Wintertime Sea Ice

PubMed Central

Junge, Karen; Eicken, Hajo; Deming, Jody W.

2004-01-01

Arctic wintertime sea-ice cores, characterized by a temperature gradient of −2 to −20°C, were investigated to better understand constraints on bacterial abundance, activity, and diversity at subzero temperatures. With the fluorescent stains 4′,6′-diamidino-2-phenylindole 2HCl (DAPI) (for DNA) and 5-cyano-2,3-ditoyl tetrazolium chloride (CTC) (for O2-based respiration), the abundances of total, particle-associated (>3-μm), free-living, and actively respiring bacteria were determined for ice-core samples melted at their in situ temperatures (−2 to −20°C) and at the corresponding salinities of their brine inclusions (38 to 209 ppt). Fluorescence in situ hybridization was applied to determine the proportions of Bacteria, Cytophaga-Flavobacteria-Bacteroides (CFB), and Archaea. Microtome-prepared ice sections also were examined microscopically under in situ conditions to evaluate bacterial abundance (by DAPI staining) and particle associations within the brine-inclusion network of the ice. For both melted and intact ice sections, more than 50% of cells were found to be associated with particles or surfaces (sediment grains, detritus, and ice-crystal boundaries). CTC-active bacteria (0.5 to 4% of the total) and cells detectable by rRNA probes (18 to 86% of the total) were found in all ice samples, including the coldest (−20°C), where virtually all active cells were particle associated. The percentage of active bacteria associated with particles increased with decreasing temperature, as did the percentages of CFB (16 to 82% of Bacteria) and Archaea (0.0 to 3.4% of total cells). These results, combined with correlation analyses between bacterial variables and measures of particulate matter in the ice as well as the increase in CFB at lower temperatures, confirm the importance of particle or surface association to bacterial activity at subzero temperatures. Measuring activity down to −20°C adds to the concept that liquid inclusions in frozen environments provide an adequate habitat for active microbial populations on Earth and possibly elsewhere. PMID:14711687

Marsupials don't adjust their thermal energetics for life in an alpine environment

PubMed Central

Cooper, Christine E.; Withers, Philip C.; Hardie, Andrew; Geiser, Fritz

2016-01-01

ABSTRACT Marsupials have relatively low body temperatures and metabolic rates, and are therefore considered to be maladapted for life in cold habitats such as alpine environments. We compared body temperature, energetics and water loss as a function of ambient temperature for 4 Antechinus species, 2 from alpine habitats and 2 from low altitude habitats. Our results show that body temperature, metabolic rate, evaporative water loss, thermal conductance and relative water economy are markedly influenced by ambient temperature for each species, as expected for endothermic mammals. However, despite some species and individual differences, habitat (alpine vs non-alpine) does not affect any of these physiological variables, which are consistent with those for other marsupials. Our study suggests that at least under the environmental conditions experienced on the Australian continent, life in an alpine habitat does not require major physiological adjustments by small marsupials and that they are physiologically equipped to deal with sub-zero temperatures and winter snow cover. PMID:28349088

Marsupials don't adjust their thermal energetics for life in an alpine environment.

PubMed

Cooper, Christine E; Withers, Philip C; Hardie, Andrew; Geiser, Fritz

2016-01-01

Marsupials have relatively low body temperatures and metabolic rates, and are therefore considered to be maladapted for life in cold habitats such as alpine environments. We compared body temperature, energetics and water loss as a function of ambient temperature for 4 Antechinus species, 2 from alpine habitats and 2 from low altitude habitats. Our results show that body temperature, metabolic rate, evaporative water loss, thermal conductance and relative water economy are markedly influenced by ambient temperature for each species, as expected for endothermic mammals. However, despite some species and individual differences, habitat (alpine vs non-alpine) does not affect any of these physiological variables, which are consistent with those for other marsupials. Our study suggests that at least under the environmental conditions experienced on the Australian continent, life in an alpine habitat does not require major physiological adjustments by small marsupials and that they are physiologically equipped to deal with sub-zero temperatures and winter snow cover.

Cryoprotection from lipoteichoic acid

NASA Astrophysics Data System (ADS)

Rice, Charles V.; Middaugh, Amy; Wickham, Jason R.; Friedline, Anthony; Thomas, Kieth J.; Johnson, Karen; Zachariah, Malcolm; Garimella, Ravindranth

2012-10-01

Numerous chemical additives lower the freezing point of water, but life at sub-zero temperatures is sustained by a limited number of biological cryoprotectants. Antifreeze proteins in fish, plants, and insects provide protection to a few degrees below freezing. Microbes have been found to survive at even lower temperatures, and with a few exceptions, antifreeze proteins are missing. Survival has been attributed to external factors, such as the high salt concentration of brine veins and adhesion to particulates or ice crystal defects. We have discovered an endogenous cryoprotectant in the cell wall of bacteria, lipoteichoic acid biopolymers. Adding 1% LTA to bacteria cultures immediately prior to freezing provides 50% survival rate, similar to the results obtained with 1% glycerol. In the absence of an additive, bacterial survival is negligible as measured with the resazurin cell viability assay. The mode of action for LTA cryoprotection is unknown. With a molecular weight of 3-5 kDa, it is unlikely to enter the cell cytoplasm. Our observations suggest that teichoic acids could provide a shell of liquid water around biofilms and planktonic bacteria, removing the need for brine veins to prevent bacterial freezing.

Alternative Fuels Data Center: Alternative Fuel Vehicles Beat the Heat,

Science.gov Websites

standard for biodiesel, American Society for Testing Materials (ASTM) D675 fuel. "E85 is widely maintenance, Roaring Fork Transit Authority, Aspen, Colorado When thinking about buying an alternative fuel Gas Vehicles in Subzero Temps Up in the high terrain of the Colorado mountains, the Roaring Fork

Multi-decadal survival of an Antarctic nematode, Plectus murrayi, in a -20°C stored moss sample.

PubMed

Kagoshima, H; Kito, K; Aizu, T; Shin-i, T; Kanda, H; Kobayashi, S; Toyoda, A; Fujiyama, A; Kohara, Y; Convey, P; Niki, H

2012-01-01

It is not clear for how long Antarctic soil nematodes might tolerate freezing. Samples of the Antarctic moss, Bryum argenteum, were collected on 1 October 1983 at Langhovde, Soya coast, eastern Antarctica and were stored at -20°C. After 25.5 years of storage, living nematodes were recovered from the samples and were identified as Plectus murrayi by morphological examination and nucleotide sequencing of ribosomal RNA loci. The nematodes can grow and reproduce in a water agar plate with bacteria (mainly Pseudomonas sp.) cultured from the moss extract. They showed freezing tolerance at -20°C and -80°C and their survival rate after exposure to -20°C, but not -80°C, was increased if they were initially frozen slowly at a high sub-zero temperature. They also showed some ability to tolerate desiccation stress.

Alginate cryogel based glucose biosensor

NASA Astrophysics Data System (ADS)

Fatoni, Amin; Windy Dwiasi, Dian; Hermawan, Dadan

2016-02-01

Cryogel is macroporous structure provides a large surface area for biomolecule immobilization. In this work, an alginate cryogel based biosensor was developed to detect glucose. The cryogel was prepared using alginate cross-linked by calcium chloride under sub-zero temperature. This porous structure was growth in a 100 μL micropipette tip with a glucose oxidase enzyme entrapped inside the cryogel. The glucose detection was based on the colour change of redox indicator, potassium permanganate, by the hydrogen peroxide resulted from the conversion of glucose. The result showed a porous structure of alginate cryogel with pores diameter of 20-50 μm. The developed glucose biosensor was showed a linear response in the glucose detection from 1.0 to 5.0 mM with a regression of y = 0.01x+0.02 and R2 of 0.994. Furthermore, the glucose biosensor was showed a high operational stability up to 10 times of uninterrupted glucose detections.

Adaptive and freeze-tolerant heteronetwork organohydrogels with enhanced mechanical stability over a wide temperature range

NASA Astrophysics Data System (ADS)

Gao, Hainan; Zhao, Ziguang; Cai, Yudong; Zhou, Jiajia; Hua, Wenda; Chen, Lie; Wang, Li; Zhang, Jianqi; Han, Dong; Liu, Mingjie; Jiang, Lei

2017-06-01

Many biological organisms with exceptional freezing tolerance can resist the damages to cells from extra-/intracellular ice crystals and thus maintain their mechanical stability at subzero temperatures. Inspired by the freezing tolerance mechanisms found in nature, here we report a strategy of combining hydrophilic/oleophilic heteronetworks to produce self-adaptive, freeze-tolerant and mechanically stable organohydrogels. The organohydrogels can simultaneously use water and oil as a dispersion medium, and quickly switch between hydrogel- and organogel-like behaviours in response to the nature of the surrounding phase. Accordingly, their surfaces display unusual adaptive dual superlyophobic in oil/water system (that is, they are superhydrophobic under oil and superoleophobic under water). Moreover, the organogel component can inhibit the ice crystallization of the hydrogel component, thus enhancing the mechanical stability of organohydrogel over a wide temperature range (-78 to 80 °C). The organohydrogels may have promising applications in complex and harsh environments.

The effect of surface charge on the thermal stability and ice recrystallization inhibition activity of antifreeze protein III (AFP III).

PubMed

Deller, R C; Carter, B M; Zampetakis, I; Scarpa, F; Perriman, A W

2018-01-01

The aim of this study was to examine the effect of chemical cationization on the structure and function of antifreeze protein III (AFP III) over an extreme temperature range (-40°C to +90°C) using far-UV synchrotron radiation circular dichroism (SRCD) and ice recrystallization inhibition (IRI) assays. Chemical cationization was able to produce a modified AFP III with a net cationic charge at physiological pH that had enhanced resistance to denaturation at elevated temperatures, with no immediate negative impact on protein structure at subzero temperatures. Furthermore, cationized AFP III retained an IRI activity similar to that of native AFP III. Consequently, chemical cationization may provide a pathway to the development of more robust antifreeze proteins as supplementary cryoprotectants in the cryopreservation of clinically relevant cells. Copyright © 2017. Published by Elsevier Inc.

Temperature evolution, injury enhancement and treatment planning in cryosurgery

NASA Astrophysics Data System (ADS)

Rewcastle, John Cameron

Cryosurgery is the in situ ablation of target tissues by exposing them to low subzero temperatures. The last ten years have seen a resurgence of the interest in low temperature medicine and an advancement in the technologies used to inflict a freezing injury. Based on a comparative study, a new Joule-Thompson based cryomachine was found to have superior control than the standard liquid nitrogen cryomachine tested. The ability of the new generation of machines to quickly change temperatures led to the hypothesis that Dynamic Cryosurgery, the generation of thermal waves by oscillating cryoprobe tip temperatures, may increase the direct injury to cells within a cryosurgical iceball. An alternative means of accomplishing the same goal is to hold the iceball at a constant size once the critical temperature has been reached by the target tissue thereby increasing the hold time of cells at subzero temperatures. This alternative was tested in-vivo with an AT-1 Dunning rat prostate model and was found to increase the lethality of the iceball. To further the understanding of the cell damage mechanisms occurring during cryosurgery freezing and thawing rates that would be experienced clinically were mimicked on a cryostage and an in-vitro map of cellular damage was created, again using the Dunning cell line. Single and double freeze-thaw cycle experiments were performed. No intracellular ice was observed during the first freeze thaw cycle and viable cells were found in all regions of the iceball. This finding supports the role of ischemia resulting from post-treatment vascular stasis as a major contributor to cell killing. Cryosurgery is currently preformed with the goal of enclosing the target tissue within a critical isotherm assumed to insure necrosis. A three dimensional model of temperatures about multiple cryoprobes was developed to predict temperatures during cryosurgery and compared to experimental data. Predictions of this model were found to be accurate within experimental error. The ablative ratio, a measure of iceball potency, was calculated for one, three and five cryoprobe configurations. Multiple cryoprobe arrays produce an iceball with an ablative ratio that increases with time then plateaus. This contrasts with the ablative ratio for a single cryoprobe which is a continually decreasing as a function of time. In an attempt to simulate the thermal environment which occurs during prostate cryosurgery a thermal model was created taking into account the heating effects of the bladder and urethra. Computer generated three-dimensional visualization of isotherms overlaid on the relevant anatomy with temperature-volume-histograms and regions of concern maps allowed quantitative assessment of the planned treatment.

Photoperiod is the main cue that triggers supercooling ability in the land snail, Helix aspersa (Gastropoda: Helicidae).

PubMed

Ansart, A; Vernon, P; Daguzan, J

2001-06-01

Helix aspersa hibernates in Brittany (western France), where it may experience subzero temperatures. Studies on cold hardiness, although scarce in land snails, have shown a seasonal variation in supercooling ability, associated with high temperatures of crystallization (Tc). In the present work, two key environmental factors, temperature and photoperiod, were studied to elucidate, how they may affect the enhancement of supercooling ability in the snails from the end of summer to winter. Nine groups of adult snails were acclimated to different combinations of photoperiod (LD-16:8, LD-12:12, and LD-8:16 h) and temperature (15, 10, and 5 degrees C). Temperature of crystallization, hemolymph osmolality, and water content were measured. The results demonstrate a significant effect of the photoperiod on Tc, i.e., shorter photoperiods induce lower Tc (LD-16:8 h, mean Tc = -3.0 degrees C, SD = 2.0; LD-12:12 h, mean Tc = -4.3 degrees C, SD = 1.9; LD-8:16 h, mean Tc = -5.2 degrees C, SD = 1.9; n = 90), whereas the acclimation temperature had no effect. Measurements of hemolymph osmolality and water content showed that osmolality is negatively correlated with water content. Mechanisms such as dehydration are involved in the decrease of Tc. A declining photoperiod triggers a lower Tc, long before the onset of winter conditions. This response may have an adaptive component, allowing individuals to cope with the mild winters typically observed in oceanic regions. Copyright 2001 Elsevier Science.

Viability, diversity and composition of the bacterial community in a high Arctic permafrost soil from Spitsbergen, Northern Norway.

PubMed

Hansen, Aviaja A; Herbert, Rodney A; Mikkelsen, Karina; Jensen, Lars Liengård; Kristoffersen, Tommy; Tiedje, James M; Lomstein, Bente Aa; Finster, Kai W

2007-11-01

The viable and non-viable fractions of the bacterial community in a 2347-year-old permafrost soil from Spitsbergen were subjected to a comprehensive investigation using culture-independent and culture-dependent methods. LIVE/DEAD BacLight staining revealed that 26% of the total number of bacterial cells were viable. Quantitatively, aerobic microcolonies, aerobic colony-forming units and culturable anaerobic bacteria comprised a minor fraction of the total number of viable bacteria, which underlines the necessity for alternative cultivation approaches in bacterial cryobiology. Sulfate reduction was detected at temperatures between -2 degrees C and 29 degrees C while methanogenesis was not detected. Bacterial diversity was high with 162 operational taxonomic units observed from 800 16S rDNA clone sequences. The 158 pure cultures isolated from the permafrost soil affiliated with 29 different bacterial genera, the majority of which have not previously been isolated from permafrost habitats. Most of the strains isolated were affiliated to the genera Cellulomonas and Arthrobacter and several of the pure cultures were closely related to bacteria reported from other cryohabitats. Characterization of viable bacterial communities in permafrost soils is important as it will enable identification of functionally important groups together with the as yet undescribed adaptations that bacteria have evolved for surviving subzero temperatures for millennia.

Dissociation and preservation of preantral follicles and immature oocytes from female dasyurid marsupials.

PubMed

Czarny, N A; Harris, M S; Rodger, J C

2009-01-01

The mammalian ovary contains numerous immature preantral follicles that are not dependent on endocrine support, unlike the more mature hormone-dependent antral follicles. Preantral follicles can be enzymatically dissociated to yield immature oocytes that survive sub-zero preservation better as they lack a temperature-sensitive meiotic spindle. These techniques are highly applicable to gamete banking, which is an urgent requirement for Australian carnivorous marsupials as several species have rapidly declining populations and risk extinction. The present study developed protocols for the transport, dissociation, preservation and culture of granulosa cell-oocyte complexes (GOC) from the ovaries of dasyurid marsupials. High viability of GOC following enzymatic dissociation is reported and it was demonstrated that GOC are of significantly better quality following refrigerated storage for 24 h compared with storage at room temperature. Oocytes from primary follicles were not damaged by cold shock or the toxicity of vitrification media and following vitrification in liquid nitrogen 69.42+/-2.44% of oocytes were viable. However, the surrounding granulosa cells demonstrated significant damage post-thaw. These granulosa cells proliferated during a 48-h culture period resulting in significant improvements in GOC quality. The present study is a valuable step towards cryostorage of dasyurid gametes and represents fundamentally important methods by which we can contribute to the conservation of Australia's native predators.

Response of selected microoganisms to experimental planetary environments

NASA Technical Reports Server (NTRS)

Foster, T. L.

1975-01-01

A microbial population profile of mixed Cape Canaveral soil samples is presented. During this investigation a few organisms were isolated which exhibit the ability to grow at 3 C, 32 C, and 55 C. Growth curves are shown for three of these isolates, one of which grows extremely well at all three temperatures. Also included are studies dealing with growth of soil populations at zero and subzero temperatures. Results indicate growth at 0 C and -5 C, but not at 15 C or -65 C. The effect of storage temperature on dry soil is presented, and results show that psychrophilic populations decrease when soil is stored at room temperature, but do not decrease when soil is stored at -65 C. Results of an experiment with the simulated Martian environment are presented and indicate that nonsporeforming rods, sporeforming rods, and cocci can reproduce in the simulated environment when nutrients and moisture are supplied. The sporeforming rods are the predominant suvivors when dry soil is subjected to this environment.

A Microfluidic Study of Megakaryocytes Membrane Transport Properties to Water and Dimethyl Sulfoxide at Suprazero and Subzero Temperatures

PubMed Central

Sun, Sijie; Shu, Zhiquan; Ding, Weiping; Reems, Jo-Anna

2011-01-01

Megakaryocytes (MKs) are the precursor cells of platelets. Cryopreservation of MKs is critical for facilitating research investigations about the biology of this important cell and may help for scaling-up ex-vivo production of platelets from MKs for clinical transfusion. Determining membrane transport properties of MKs to water and cryoprotectant agents (CPAs) is essential for developing optimal conditions for cryopreserving MKs. To obtain these unknown parameters, membrane transport properties of the human UT-7/TPO megakaryocytic cell line were investigated using a microfluidic perfusion system. UT-7/TPO cells were immobilized in a microfluidic system on poly-D-lysine-coated glass substrate and perfused with various hyper-osmotic salt and CPA solutions at suprazero and subzero temperatures. The kinetics of cell volume changes under various extracellular conditions were monitored by a video camera and the information was processed and analyzed using the Kedem–Katchalsky model to determine the membrane transport properties. The osmotically inactive cell volume (Vb=0.15), the permeability coefficient to water (Lp) at 37°C, 22°C, 12°C, 0°C, −5°C, −10°C, and −20°C, and dimethyl sulfoxide (DMSO; Ps) at 22, 12, 0, −10, −20, as well as associated activation energies of water and DMSO at different temperature regions were obtained. We found that MKs have relatively higher membrane permeability to water (Lp=2.62 μm/min/atm at 22°C) and DMSO (Ps=1.8×10−3 cm/min at 22°C) than most other common mammalian cell types, such as lymphocytes (Lp=0.46 μm/min/atm at 25°C). This information could suggest a higher optimal cooling rate for MKs cryopreservation. The discontinuity effect was also found on activation energy at 0°C–12°C in the Arrhenius plots of membrane permeability by evaluating the slope of linear regression at each temperature region. This phenomenon may imply the occurrence of cell membrane lipid phase transition. PMID:22232706

A Vivens Ex Vivo Study on the Synergistic Effect of Electrolysis and Freezing on the Cell Nucleus.

PubMed

Lugnani, Franco; Zanconati, Fabrizio; Marcuzzo, Thomas; Bottin, Cristina; Mikus, Paul; Guenther, Enric; Klein, Nina; Rubinsky, Liel; Stehling, Michael K; Rubinsky, Boris

2015-01-01

Freezing-cryosurgery, and electrolysis-electrochemical therapy (EChT), are two important minimally invasive surgery tissue ablation technologies. Despite major advantages they also have some disadvantages. Cryosurgery cannot induce cell death at high subzero freezing temperatures and requires multiple freeze thaw cycles, while EChT requires high concentrations of electrolytic products-which makes it a lengthy procedure. Based on the observation that freezing increases the concentration of solutes (including products of electrolysis) in the frozen region and permeabilizes the cell membrane to these products, this study examines the hypothesis that there could be a synergistic effect between freezing and electrolysis in their use together for tissue ablation. Using an animal model we refer to as vivens ex vivo, which may be of value in reducing the use of animals for experiments, combined with a Hematoxylin stain of the nucleus, we show that there are clinically relevant protocols in which the cell nucleus appears intact when electrolysis and freezing are used separately but is affected by certain combinations of electrolysis and freezing.

A Vivens Ex Vivo Study on the Synergistic Effect of Electrolysis and Freezing on the Cell Nucleus

PubMed Central

Lugnani, Franco; Zanconati, Fabrizio; Marcuzzo, Thomas; Bottin, Cristina; Mikus, Paul; Guenther, Enric; Klein, Nina; Rubinsky, Liel; Stehling, Michael K.; Rubinsky, Boris

2015-01-01

Freezing—cryosurgery, and electrolysis—electrochemical therapy (EChT), are two important minimally invasive surgery tissue ablation technologies. Despite major advantages they also have some disadvantages. Cryosurgery cannot induce cell death at high subzero freezing temperatures and requires multiple freeze thaw cycles, while EChT requires high concentrations of electrolytic products—which makes it a lengthy procedure. Based on the observation that freezing increases the concentration of solutes (including products of electrolysis) in the frozen region and permeabilizes the cell membrane to these products, this study examines the hypothesis that there could be a synergistic effect between freezing and electrolysis in their use together for tissue ablation. Using an animal model we refer to as vivens ex vivo, which may be of value in reducing the use of animals for experiments, combined with a Hematoxylin stain of the nucleus, we show that there are clinically relevant protocols in which the cell nucleus appears intact when electrolysis and freezing are used separately but is affected by certain combinations of electrolysis and freezing. PMID:26695185

Physiological and biochemical responses to cold and drought in the rock-dwelling pulmonate snail, Chondrina avenacea.

PubMed

Koštál, Vladimír; Rozsypal, Jan; Pech, Pavel; Zahradníčková, Helena; Šimek, Petr

2013-08-01

The pulmonate snail Chondrina avenacea lives on exposed rock walls where it experiences drastic daily and seasonal fluctuations of abiotic conditions and food availability. We found that tolerance to dry conditions was maintained at a very high level throughout the year and was mainly based on the snails' ability to promptly enter into estivation (quiescence) whenever they experienced drying out of their environment. Snails rapidly suppressed their metabolism and minimized their water loss using discontinuous gas exchange pattern. The metabolic suppression probably included periods of tissue hypoxia and anaerobism as indicated by accumulation of typical end products of anaerobic metabolism: lactate, alanine and succinate. Though the drought-induced metabolic suppression was sufficient to stimulate moderate increase of supercooling capacity, the seasonally highest levels of supercooling capacity and the highest tolerance to subzero temperatures were tightly linked to hibernation (diapause). Hibernating snails did not survive freezing of their body fluids and instead relied on supercooling strategy which allowed them to survive when air temperatures dropped to as low as -21 °C. No accumulation of low-molecular weight compounds (potential cryoprotectants) was detected in hibernating snails except for small amounts of the end products of anaerobic metabolism.

Heat exchanger development at Reaction Engines Ltd.

NASA Astrophysics Data System (ADS)

Varvill, Richard

2010-05-01

The SABRE engine for SKYLON has a sophisticated thermodynamic cycle with heat transfer between the fluid streams. The intake airflow is cooled in an efficient counterflow precooler, consisting of many thousand small bore thin wall tubes. Precooler manufacturing technology has been under investigation at REL for a number of years with the result that flightweight matrix modules can now be produced. A major difficulty with cooling the airflow to sub-zero temperatures at low altitude is the problem of frost formation. Frost control technology has been developed which enables steady state operation. The helium loop requires a top cycle heat exchanger (HX3) to deliver a constant inlet temperature to the main turbine. This is constructed in silicon carbide and the feasibility of manufacturing various matrix geometries has been investigated along with suitable joining techniques. A demonstration precooler will be made to run in front of a Viper jet engine at REL's B9 test facility in 2011. This precooler will incorporate full frost control and be built from full size SABRE engine modules. The facility will incorporate a high pressure helium loop that rejects the absorbed heat to a bath of liquid nitrogen.

Influence of Block Copolymerization on the Antifreeze Protein Mimetic Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol).

PubMed

Congdon, Thomas R; Notman, Rebecca; Gibson, Matthew I

2016-09-12

Antifreeze (glyco) proteins are produced by many cold-acclimatized species to enable them to survive subzero temperatures. These proteins have multiple macroscopic effects on ice crystal growth which makes them appealing for low-temperature applications-from cellular cryopreservation to food storage. Poly(vinyl alcohol) has remarkable ice recrystallization inhibition activity, but its mode of action is uncertain as is the extent at which it can be incorporated into other high-order structures. Here the synthesis and characterization of well-defined block copolymers containing poly(vinyl alcohol) and poly(vinylpyrrolidone) by RAFT/MADIX polymerization is reported, as new antifreeze protein mimetics. The effect of adding a large second hydrophilic block is studied across a range of compositions, and it is found to be a passive component in ice recrystallization inhibition assays, enabling retention of all activity. In the extreme case, a block copolymer with only 10% poly(vinyl alcohol) was found to retain all activity, where statistical copolymers of PVA lose all activity with very minor changes to composition. These findings present a new method to increase the complexity of antifreeze protein mimetic materials, while retaining activity, and also to help understand the underlying mechanisms of action.

Influence of Block Copolymerization on the Antifreeze Protein Mimetic Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol)

PubMed Central

2016-01-01

Antifreeze (glyco) proteins are produced by many cold-acclimatized species to enable them to survive subzero temperatures. These proteins have multiple macroscopic effects on ice crystal growth which makes them appealing for low-temperature applications—from cellular cryopreservation to food storage. Poly(vinyl alcohol) has remarkable ice recrystallization inhibition activity, but its mode of action is uncertain as is the extent at which it can be incorporated into other high-order structures. Here the synthesis and characterization of well-defined block copolymers containing poly(vinyl alcohol) and poly(vinylpyrrolidone) by RAFT/MADIX polymerization is reported, as new antifreeze protein mimetics. The effect of adding a large second hydrophilic block is studied across a range of compositions, and it is found to be a passive component in ice recrystallization inhibition assays, enabling retention of all activity. In the extreme case, a block copolymer with only 10% poly(vinyl alcohol) was found to retain all activity, where statistical copolymers of PVA lose all activity with very minor changes to composition. These findings present a new method to increase the complexity of antifreeze protein mimetic materials, while retaining activity, and also to help understand the underlying mechanisms of action. PMID:27476873

Growth of the Facultative Anaerobes from Antarctica, Alaska, and Patagonia at Low Temperatures

NASA Technical Reports Server (NTRS)

Pikuta, Elena V.; Hoover, Richard B.

2004-01-01

Psychotolerance, as an adaptation for surviving in extreme environments, is widespread among mesophilic microorganisms. Physico-chemical factors such as pressure, red-ox potential, pH and salinity could significantly alter the features of ecosystems by providing liquid water at subzero temperatures. Furthermore, organisms can respond to temperature changes by several known mechanisms, including changing the conformation capacities of constitutional proteins or by the synthesis of mucopolysaccharides around the cell wall and membrane. Such protective mechanisms make it possible for cells to not only passively survive low temperatures in a state of anabiosis, but also to be capable of actively metabolizing substrates and reproducing normally. The physiological and biochemical characteristics of the species, as well as genetics, could be remarkably changed due to adaptation and surviving in extreme environments. The cold shock genes of some of the studied strains of psychotolerant facultative anaerobes were reported previously. In this paper we present experimental data for psychotolerant, non spore-forming, facultative anaerobes isolated from geographically different cold regions of our planet. We show the growth response on changing from anaerobic conditions to aerobic with cultivation at low temperatures.

Intracellular ice formation in mouse zygotes and early morulae vs. cooling rate and temperature-experimental vs. theory.

PubMed

Jin, Bo; Seki, Shinsuke; Paredes, Estefania; Qiu, Juan; Shi, Yanbin; Zhang, Zhenqiang; Ma, Chao; Jiang, Shuyan; Li, Jiaqi; Yuan, Feng; Wang, Shu; Shao, Xiaoguang; Mazur, Peter

2016-10-01

In this study, mature female mice of the ICR strain were induced to superovultate, mated, and collected at either zygote or early morula stages. Embryos suspended in 1 M ethylene glycol in PBS containing 10 mg/L Snomax for 15 min, then transferred in sample holder to Linkam cryostage, cooled to and seeded at 7 °C, and then observed and photographed while being cooled to -70 °C at 0.5-20 °C/min. Intracellular ice formation (IIF) was observed as abrupt ''flashing''. Two types of flashing or IIF were observed in this study. Extracellular freezing occurred at a mean of -7.7 °C. In morulae, about 25% turned dark within ±1 °C of extracellular ice formation (EIF). These we refer to as "high temperature'' flashers. In zygotes, there were no high temperature flashers. All the zygotes flashed at temperatures well below the temperature for EIF. Presumably high temperature flashers were a consequence of membrane damage prior to EIF or damage from EIF. We shall not discuss them further. In the majority of cases, IIF occurred well below -7.7 °C; these we call ''low temperature'' flashers. None flashed with cooling rate (CR) of 0.5 °C/min in either zygotes or morulae. Nearly all flashed with CR of 4 °C/min or higher, but the distribution of temperatures is much broader with morulae than with zygotes. Also, the mean flashing temperature is much higher with morulae (-20.9 °C) than with zygotes (-40.3 °C). We computed the kinetics of water loss with respect to CR and temperature in both mouse zygotes and in morulae based on published estimates of Lp and it is Ea. The resulting dehydration curves combined with knowledge of the embryo nucleation temperature permits an estimate of the likelihood of IIF as a function of CR and subzero temperature. The agreement between these computed probabilities and the observed values are good. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Prebiotic chemistry in eutectic solutions at the water-ice matrix.

PubMed

Menor-Salván, César; Marín-Yaseli, Margarita R

2012-08-21

A crystalline ice matrix at subzero temperatures can maintain a liquid phase where organic solutes and salts concentrate to form eutectic solutions. This concentration effect converts the confined reactant solutions in the ice matrix, sometimes making condensation and polymerisation reactions occur more favourably. These reactions occur at significantly high rates from a prebiotic chemistry standpoint, and the labile products can be protected from degradation. The experimental study of the synthesis of nitrogen heterocycles at the ice-water system showed the efficiency of this scenario and could explain the origin of nucleobases in the inner Solar System bodies, including meteorites and extra-terrestrial ices, and on the early Earth. The same conditions can also favour the condensation of monomers to form ribonucleic acid and peptides. Together with the synthesis of these monomers, the ice world (i.e., the chemical evolution in the range between the freezing point of water and the limit of stability of liquid brines, 273 to 210 K) is an under-explored experimental model in prebiotic chemistry.

Behavioural and physiological adaptations to low-temperature environments in the common frog, Rana temporaria.

PubMed

Muir, Anna P; Biek, Roman; Mable, Barbara K

2014-05-23

Extreme environments can impose strong ecological and evolutionary pressures at a local level. Ectotherms are particularly sensitive to low-temperature environments, which can result in a reduced activity period, slowed physiological processes and increased exposure to sub-zero temperatures. The aim of this study was to assess the behavioural and physiological responses that facilitate survival in low-temperature environments. In particular, we asked: 1) do high-altitude common frog (Rana temporaria) adults extend the time available for larval growth by breeding at lower temperatures than low-altitude individuals?; and 2) do tadpoles sampled from high-altitude sites differ physiologically from those from low-altitude sites, in terms of routine metabolic rate (RMR) and freeze tolerance? Breeding date was assessed as the first day of spawn observation and local temperature recorded for five, paired high- and low-altitude R. temporaria breeding sites in Scotland. Spawn was collected and tadpoles raised in a common laboratory environment, where RMR was measured as oxygen consumed using a closed respiratory tube system. Freeze tolerance was measured as survival following slow cooling to the point when all container water had frozen. We found that breeding did not occur below 5°C at any site and there was no significant relationship between breeding temperature and altitude, leading to a delay in spawning of five days for every 100 m increase in altitude. The relationship between altitude and RMR varied by mountain but was lower for individuals sampled from high- than low-altitude sites within the three mountains with the highest high-altitude sites (≥900 m). In contrast, individuals sampled from low-altitudes survived freezing significantly better than those from high-altitudes, across all mountains. Our results suggest that adults at high-altitude do not show behavioural adaptations in terms of breeding at lower temperatures. However, tadpoles appear to have the potential to adapt physiologically to surviving at high-altitude via reduced RMR but without an increase in freeze tolerance. Therefore, survival at high-altitude may be facilitated by physiological mechanisms that permit faster growth rates, allowing completion of larval development within a shorter time period, alleviating the need for adaptations that extend the time available for larval growth.

Conservation at a slow pace: terrestrial gastropods facing fast-changing climate

PubMed Central

Ansart, Armelle

2017-01-01

Abstract The climate is changing rapidly, and terrestrial ectotherms are expected to be particularly vulnerable to changes in temperature and water regime, but also to an increase in extreme weather events in temperate regions. Physiological responses of terrestrial gastropods to climate change are poorly studied. This is surprising, because they are of biodiversity significance among litter-dwelling species, playing important roles in ecosystem function, with numerous species being listed as endangered and requiring efficient conservation management. Through a summary of our ecophysiological work on snail and slug species, we gained some insights into physiological and behavioural responses to climate change that we can organize into the following four threat categories. (i) Winter temperature and snow cover. Terrestrial gastropods use different strategies to survive sub-zero temperatures in buffered refuges, such as the litter or the soil. Absence of the insulating snow cover exposes species to high variability in temperature. The extent of specific cold tolerance might influence the potential of local extinction, but also of invasion. (ii) Drought and high temperature. Physiological responses involve high-cost processes that protect against heat and dehydration. Some species decrease activity periods, thereby reducing foraging and reproduction time. Related costs and physiological limits are expected to increase mortality. (iii) Extreme events. Although some terrestrial gastropod communities can have a good resilience to fire, storms and flooding, an increase in the frequency of those events might lead to community impoverishment. (iv) Habitat loss and fragmentation. Given that terrestrial gastropods are poorly mobile, landscape alteration generally results in an increased risk of local extinction, but responses are highly variable between species, requiring studies at the population level. There is a great need for studies involving non-invasive methods on the plasticity of physiological and behavioural responses and the ability for local adaptation, considering the spatiotemporally heterogeneous climatic landscape, to allow efficient management of ecosystems and conservation of biodiversity. PMID:28852510

Conservation at a slow pace: terrestrial gastropods facing fast-changing climate.

PubMed

Nicolai, Annegret; Ansart, Armelle

2017-01-01

The climate is changing rapidly, and terrestrial ectotherms are expected to be particularly vulnerable to changes in temperature and water regime, but also to an increase in extreme weather events in temperate regions. Physiological responses of terrestrial gastropods to climate change are poorly studied. This is surprising, because they are of biodiversity significance among litter-dwelling species, playing important roles in ecosystem function, with numerous species being listed as endangered and requiring efficient conservation management. Through a summary of our ecophysiological work on snail and slug species, we gained some insights into physiological and behavioural responses to climate change that we can organize into the following four threat categories. (i) Winter temperature and snow cover. Terrestrial gastropods use different strategies to survive sub-zero temperatures in buffered refuges, such as the litter or the soil. Absence of the insulating snow cover exposes species to high variability in temperature. The extent of specific cold tolerance might influence the potential of local extinction, but also of invasion. (ii) Drought and high temperature. Physiological responses involve high-cost processes that protect against heat and dehydration. Some species decrease activity periods, thereby reducing foraging and reproduction time. Related costs and physiological limits are expected to increase mortality. (iii) Extreme events. Although some terrestrial gastropod communities can have a good resilience to fire, storms and flooding, an increase in the frequency of those events might lead to community impoverishment. (iv) Habitat loss and fragmentation. Given that terrestrial gastropods are poorly mobile, landscape alteration generally results in an increased risk of local extinction, but responses are highly variable between species, requiring studies at the population level. There is a great need for studies involving non-invasive methods on the plasticity of physiological and behavioural responses and the ability for local adaptation, considering the spatiotemporally heterogeneous climatic landscape, to allow efficient management of ecosystems and conservation of biodiversity.

High pressure inactivation of Pseudomonas in black truffle - comparison with Pseudomonas fluorescens in tryptone soya broth

NASA Astrophysics Data System (ADS)

Ballestra, Patricia; Verret, Catherine; Cruz, Christian; Largeteau, Alain; Demazeau, Gerard; El Moueffak, Abdelhamid

2010-03-01

Pseudomonas is one of the most common genera in black Perigord truffle. Its inactivation by high pressure (100-500 MPa/10 min) applied on truffles at sub-zero or low temperatures was studied and compared with those of Pseudomonas fluorescens in tryptone soya broth. Pressurization of truffles at 300 MPa/4 °C reduced the bacterial count of Pseudomonas by 5.3 log cycles. Higher pressures of 400 or 500 MPa, at 4 °C or 20 °C, allowed us to slightly increase the level of destruction to the value of ca. 6.5 log cycles but did not permit us to completely inactivate Pseudomonas. The results showed a residual charge of about 10 CFU/g. Pressure-shift freezing of truffles, which consists in applying a pressure of 200 MPa/-18 °C for 10 min and then quickly releasing this pressure to induce freezing, reduced the population of Pseudomonas by 3.3 log cycles. The level of inactivation was higher than those obtained with conventional freezing. Endogenous Pseudomonas in truffle was shown to be more resistant to high pressure treatments than P. fluorescens used for inoculation of broths.

Nonionic diethanolamide amphiphiles with isoprenoid-type hydrocarbon chains: thermotropic and lyotropic liquid crystalline phase behaviour

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sagnella, Sharon M.; Conn, Charlotte E.; Krodkiewska, Irena

2014-09-24

The thermotropic and lyotropic liquid crystalline phase behaviour of a series of diethanolamide amphiphiles with isoprenoid-type hydrocarbon chains (geranoyl, H-farnesoyl, and phytanoyl) has been investigated. When neat, both H-farnesoyl and phytanoyl diethanolamide form a smectic liquid crystalline structure at sub-zero temperatures. In addition, all three diethanolamides exhibit a glass transition temperature at around -73 C. Geranoyl diethanolamide forms a lamellar crystalline phase with a lattice parameter of 17.4 {angstrom} following long term storage accompanied by the loss of the glass transition. In the presence of water, H-farnesoyl and phytanoyl diethanolamide form lyotropic liquid crystalline phases, whilst geranoyl diethanolamide forms anmore » L{sub 2} phase. H-farnesoyl diethanolamide forms a fluid lamellar phase (L{sub {alpha}}) at room temperature and up to {approx} 40 C. Phytanoyl diethanolamide displays a rich mesomorphism forming the inverse diamond (Q{sub II}{sup D}) and gyroid (Q{sub II}{sup G}) bicontinuous cubic phases in addition to an L{sub {alpha}} phase.« less

Effect of solution non-ideality on erythrocyte volume regulation.

PubMed

Levin, R L; Cravalho, E G; Huggins, C E

1977-03-01

A non-ideal, hydrated, non-dilute pseudo-binary salt-protein-water solution model of the erythrocyte intracellular solution is presented to describe the osmotic behavior of human erythrocytes. Existing experimental activity data for salts and proteins in aqueous solutions are used to formulate van Laar type expressions for the solvent and solute activity coefficients. Reasonable estimates can therefore be made of the non-ideality of the erythrocyte intracellular solution over a wide range of osmolalities. Solution non-ideality is shown to affect significantly the degree of solute polarization within the erythrocyte intracellular solution during freezing. However, the non-ideality has very little effect upon the amount of water retained within erythrocytes cooled at sub-zero temperatures.

Accumulation of lactate by supercooled hatchlings of the painted turtle (Chrysemys picta): implications for overwinter survival.

PubMed

Hartley, L M; Packard, M J; Packard, G C

2000-02-01

Hatchlings of the North American painted turtle (Chrysemys picta) typically spend their first winter of life inside the shallow, subterranean nest where they completed embryogenesis the preceding summer. Neonates at northern localities consequently may be exposed during winter to subzero temperatures and frozen soil. Hatchlings apparently survive exposure to such conditions by supercooling, but the physiological consequences of this adaptive strategy have not been examined. We measured lactate in hatchling painted turtles after exposure to each of three temperatures (0 degree C, -4 degrees C, and -8 degrees C) for three time periods (5 days, 15 days, and 25 days) to determine the extent to which overwintering hatchlings might rely on anaerobic metabolism to regenerate ATP. Whole-body lactate increased with increasing duration of exposure and decreasing temperature, and the highest levels were associated with the group that experienced the highest mortality. These results indicate that animals may develop a considerable lactic acidosis during a winter in which temperatures fall below 0 degree C for weeks or months and that accumulation of lactate may contribute to mortality of overwintering animals.

Expression of genes involved in energy mobilization and osmoprotectant synthesis during thermal and dehydration stress in the Antarctic midge, Belgica antarctica.

PubMed

Teets, Nicholas M; Kawarasaki, Yuta; Lee, Richard E; Denlinger, David L

2013-02-01

The Antarctic midge, Belgica antarctica, experiences sub-zero temperatures and desiccating conditions for much of the year, and in response to these environmental insults, larvae undergo rapid shifts in metabolism, mobilizing carbohydrate energy reserves to promote synthesis of low-molecular-mass osmoprotectants. In this study, we measured the expression of 11 metabolic genes in response to thermal and dehydration stress. During both heat and cold stress, we observed upregulation of phosphoenolpyruvate carboxykinase (pepck) and glycogen phosphorylase (gp) to support rapid glucose mobilization. In contrast, there was a general downregulation of pathways related to polyol, trehalose, and proline synthesis during both high- and low-temperature stress. Pepck was likewise upregulated in response to different types of dehydration stress; however, for many of the other genes, expression patterns depended on the nature of dehydration stress. Following fast dehydration, expression patterns were similar to those observed during thermal stress, i.e., upregulation of gp accompanied by downregulation of trehalose and proline synthetic genes. In contrast, gradual, prolonged dehydration (both at a constant temperature and in conjunction with chilling) promoted marked upregulation of genes responsible for trehalose and proline synthesis. On the whole, our data agree with known metabolic adaptations to stress in B. antarctica, although a few discrepancies between gene expression patterns and downstream metabolite contents point to fluxes that are not controlled at the level of transcription.

Metal-Organic Frameworks in Adsorption-Driven Heat Pumps: The Potential of Alcohols as Working Fluids.

PubMed

de Lange, Martijn F; van Velzen, Benjamin L; Ottevanger, Coen P; Verouden, Karlijn J F M; Lin, Li-Chiang; Vlugt, Thijs J H; Gascon, Jorge; Kapteijn, Freek

2015-11-24

A large fraction of global energy is consumed for heating and cooling. Adsorption-driven heat pumps and chillers could be employed to reduce this consumption. MOFs are often considered to be ideal adsorbents for heat pumps and chillers. While most published works to date on this topic have focused on the use of water as a working fluid, the instability of many MOFs to water and the fact that water cannot be used at subzero temperatures pose certain drawbacks. The potential of using alcohol-MOF pairs in adsorption-driven heat pumps and chillers is investigated. To this end, 18 different selected MOF structures in combination with either methanol or ethanol as a working fluid are considered, and their potential is assessed on the basis of adsorption measurements and thermodynamic efficiencies. If alcohols are used instead of water, then (1) adsorption occurs at lower relative pressures for methanol and even lower pressure for ethanol, (2) larger pores can be utilized efficiently, as hysteresis is absent for pores smaller than 3.4 nm (2 nm for water), (3) larger pore sizes need to be employed to ensure the desired stepwise adsorption, (4) the effect of (polar/apolar) functional groups in the MOF is far less pronounced, (5) the energy released or taken up per cycle is lower, but heat and mass transfer may be enhanced, (6) stability of MOFs seems to be less of an issue, and (7) cryogenic applications (e.g., ice making) become feasible. From a thermodynamic perspective, UiO-67, CAU-3, and ZIF-8 seem to be the most promising MOFs for both methanol and ethanol as working fluids. Although UiO-67 might not be completely stable, both CAU-3 and ZIF-8 have the potential to be applied, especially in subzero-temperature adsorption chillers (AC).

Cloning and characterization of aquaglyceroporin genes from rainbow smelt (Osmerus mordax) and transcript expression in response to cold temperature.

PubMed

Hall, Jennifer R; Clow, Kathy A; Rise, Matthew L; Driedzic, William R

2015-09-01

Aquaglyceroporins (GLPs) are integral membrane proteins that facilitate passive movement of water, glycerol and urea across cellular membranes. In this study, GLP-encoding genes were characterized in rainbow smelt (Osmerus mordax mordax), an anadromous teleost that accumulates high glycerol and modest urea levels in plasma and tissues as an adaptive cryoprotectant mechanism in sub-zero temperatures. We report the gene and promoter sequences for two aqp10b paralogs (aqp10ba, aqp10bb) that are 82% identical at the predicted amino acid level, and aqp9b. Aqp10bb and aqp9b have the 6 exon structure common to vertebrate GLPs. Aqp10ba has 8 exons; there are two additional exons at the 5' end, and the promoter sequence is different from aqp10bb. Molecular phylogenetic analysis suggests that the aqp10b paralogs arose from a gene duplication event specific to the smelt lineage. Smelt GLP transcripts are ubiquitously expressed; however, aqp10ba transcripts were highest in kidney, aqp10bb transcripts were highest in kidney, intestine, pyloric caeca and brain, and aqp9b transcripts were highest in spleen, liver, red blood cells and kidney. In cold-temperature challenge experiments, plasma glycerol and urea levels were significantly higher in cold- compared to warm-acclimated smelt; however, GLP transcript levels were generally either significantly lower or remained constant. The exception was significantly higher aqp10ba transcript levels in kidney. High aqp10ba transcripts in smelt kidney that increase significantly in response to cold temperature in congruence with plasma urea suggest that this gene duplicate may have evolved to allow the re-absorption of urea to concomitantly conserve nitrogen and prevent freezing. Copyright © 2015 Elsevier Inc. All rights reserved.

Activation of photoprotective winter photoinhibition in plants from different environments: a literature compilation and meta-analysis.

PubMed

Míguez, Fátima; Fernández-Marín, Beatriz; Becerril, José María; García-Plazaola, José Ignacio

2015-12-01

Overwintering plants face a pronounced imbalance between light capture and use of that excitation for photosynthesis. In response, plants upregulate thermal dissipation, with concomitant reductions in photochemical efficiency, in a process characterized by a slow recovery upon warming. These sustained depressions of photochemical efficiency are termed winter photoinhibition (WPI) here. WPI has been extensively studied in conifers and in few overwintering crops, but other plant species have received less attention. Furthermore, the literature shows some controversies about the association of WPI with xanthophylls and the environmental conditions that control xanthophylls conversion. To overview current knowledge and identify knowledge gaps on WPI mechanisms, we performed a comprehensive meta-analysis of literature published over the period 1991-2011. All publications containing measurements of Fv/Fm for a cold period and a corresponding warm control were included in our final database of 190 studies on 162 species. WPI was estimated as the relative decrease in Fv/Fm. High WPI was always accompanied by a high (A + Z)/(V + A + Z). Activation of lasting WPI was directly related to air temperature, with a threshold of around 0°C. Tropical plants presented earlier (at a temperature of >0°C) and higher WPI than non-tropical plants. We conclude that (1) activation of a xanthophyll-dependent mechanism of WPI is a requisite for maintaining photosynthetic structures at sub-zero temperatures, while (2) absence (or low levels) of WPI is not necessarily related to low (A + Z)/(V + A + Z); and (3) the air temperature that triggers lasting WPI, and the maximum level of WPI, do not depend on plant growth habit or bioclimatic origin of species. © 2015 Scandinavian Plant Physiology Society.

Long-term growth of Ginkgo with CO(2) enrichment increases leaf ice nucleation temperatures and limits recovery of the photosynthetic system from freezing.

PubMed

Terry, A C; Quick, W P; Beerling, D J

2000-09-01

The importance of subzero temperature interactions with elevated CO(2) on plant carbon metabolism has received rather little attention, despite their likely role in influencing future vegetation productivity and dynamics. Here we focused on the critical issues of CO(2)-enrichment effects on leaf-freezing temperatures, subsequent membrane damage, and recovery of the photosynthetic system. We show that growth in elevated CO(2) (70 Pa) results in a substantial and significant (P<0.01) increase (up to 4 degrees C) in the ice nucleation temperature of leaves of Maidenhair tree (Ginkgo biloba), which was observed consistently throughout the 1999 growing season relative to their ambient CO(2) (35 Pa) counterparts. We suggest that increased sensitivity of leaves to ice damage after growth in elevated CO(2) provides an explanation for increased photoinhibition observed in the field early and late in the growing season when low nighttime temperatures are experienced. This new mechanism is proposed in addition to the earlier postulated explanation for this phenomenon involving a reduction in the rate of triose-P utilization owing to a decrease in the rate of carbohydrate export from the leaf.

Long-Term Growth of Ginkgo with CO2 Enrichment Increases Leaf Ice Nucleation Temperatures and Limits Recovery of the Photosynthetic System from Freezing1

PubMed Central

Terry, Andrew C.; Quick, W. Paul; Beerling, David J.

2000-01-01

The importance of subzero temperature interactions with elevated CO2 on plant carbon metabolism has received rather little attention, despite their likely role in influencing future vegetation productivity and dynamics. Here we focused on the critical issues of CO2-enrichment effects on leaf-freezing temperatures, subsequent membrane damage, and recovery of the photosynthetic system. We show that growth in elevated CO2 (70 Pa) results in a substantial and significant (P < 0.01) increase (up to 4°C) in the ice nucleation temperature of leaves of Maidenhair tree (Ginkgo biloba), which was observed consistently throughout the 1999 growing season relative to their ambient CO2 (35 Pa) counterparts. We suggest that increased sensitivity of leaves to ice damage after growth in elevated CO2 provides an explanation for increased photoinhibition observed in the field early and late in the growing season when low nighttime temperatures are experienced. This new mechanism is proposed in addition to the earlier postulated explanation for this phenomenon involving a reduction in the rate of triose-P utilization owing to a decrease in the rate of carbohydrate export from the leaf. PMID:10982433

A Low Temperature Limit for Life on Earth

PubMed Central

Clarke, Andrew; Morris, G. John; Fonseca, Fernanda; Murray, Benjamin J.; Price, Hannah C.

2013-01-01

There is no generally accepted value for the lower temperature limit for life on Earth. We present empirical evidence that free-living microbial cells cooling in the presence of external ice will undergo freeze-induced desiccation and a glass transition (vitrification) at a temperature between −10°C and −26°C. In contrast to intracellular freezing, vitrification does not result in death and cells may survive very low temperatures once vitrified. The high internal viscosity following vitrification means that diffusion of oxygen and metabolites is slowed to such an extent that cellular metabolism ceases. The temperature range for intracellular vitrification makes this a process of fundamental ecological significance for free-living microbes. It is only where extracellular ice is not present that cells can continue to metabolise below these temperatures, and water droplets in clouds provide an important example of such a habitat. In multicellular organisms the cells are isolated from ice in the environment, and the major factor dictating how they respond to low temperature is the physical state of the extracellular fluid. Where this fluid freezes, then the cells will dehydrate and vitrify in a manner analogous to free-living microbes. Where the extracellular fluid undercools then cells can continue to metabolise, albeit slowly, to temperatures below the vitrification temperature of free-living microbes. Evidence suggests that these cells do also eventually vitrify, but at lower temperatures that may be below −50°C. Since cells must return to a fluid state to resume metabolism and complete their life cycle, and ice is almost universally present in environments at sub-zero temperatures, we propose that the vitrification temperature represents a general lower thermal limit to life on Earth, though its precise value differs between unicellular (typically above −20°C) and multicellular organisms (typically below −20°C). Few multicellular organisms can, however, complete their life cycle at temperatures below ∼−2°C. PMID:23840425

A Low Temperature Limit for Life on Earth.

PubMed

Clarke, Andrew; Morris, G John; Fonseca, Fernanda; Murray, Benjamin J; Acton, Elizabeth; Price, Hannah C

2013-01-01

There is no generally accepted value for the lower temperature limit for life on Earth. We present empirical evidence that free-living microbial cells cooling in the presence of external ice will undergo freeze-induced desiccation and a glass transition (vitrification) at a temperature between -10°C and -26°C. In contrast to intracellular freezing, vitrification does not result in death and cells may survive very low temperatures once vitrified. The high internal viscosity following vitrification means that diffusion of oxygen and metabolites is slowed to such an extent that cellular metabolism ceases. The temperature range for intracellular vitrification makes this a process of fundamental ecological significance for free-living microbes. It is only where extracellular ice is not present that cells can continue to metabolise below these temperatures, and water droplets in clouds provide an important example of such a habitat. In multicellular organisms the cells are isolated from ice in the environment, and the major factor dictating how they respond to low temperature is the physical state of the extracellular fluid. Where this fluid freezes, then the cells will dehydrate and vitrify in a manner analogous to free-living microbes. Where the extracellular fluid undercools then cells can continue to metabolise, albeit slowly, to temperatures below the vitrification temperature of free-living microbes. Evidence suggests that these cells do also eventually vitrify, but at lower temperatures that may be below -50°C. Since cells must return to a fluid state to resume metabolism and complete their life cycle, and ice is almost universally present in environments at sub-zero temperatures, we propose that the vitrification temperature represents a general lower thermal limit to life on Earth, though its precise value differs between unicellular (typically above -20°C) and multicellular organisms (typically below -20°C). Few multicellular organisms can, however, complete their life cycle at temperatures below ∼-2°C.

Long-term preservation of anammox bacteria.

PubMed

Rothrock, Michael J; Vanotti, Matias B; Szögi, Ariel A; Gonzalez, Maria Cruz Garcia; Fujii, Takao

2011-10-01

Deposit of useful microorganisms in culture collections requires long-term preservation and successful reactivation techniques. The goal of this study was to develop a simple preservation protocol for the long-term storage and reactivation of the anammox biomass. To achieve this, anammox biomass was frozen or lyophilized at two different freezing temperatures (-60°C and in liquid nitrogen (-200°C)) in skim milk media (with and without glycerol), and the reactivation of anammox activity was monitored after a 4-month storage period. Of the different preservation treatments tested, only anammox biomass preserved via freezing in liquid nitrogen followed by lyophilization in skim milk media without glycerol achieved stoichiometric ratios for the anammox reaction similar to the biomass in both the parent bioreactor and in the freshly harvested control treatment. A freezing temperature of -60°C alone, or in conjunction with lyophilization, resulted in the partial recovery of the anammox bacteria, with an equal mixture of anammox and nitrifying bacteria in the reactivated biomass. To our knowledge, this is the first report of the successful reactivation of anammox biomass preserved via sub-zero freezing and/or lyophilization. The simple preservation protocol developed from this study could be beneficial to accelerate the integration of anammox-based processes into current treatment systems through a highly efficient starting anammox biomass.

Preservation of potassium balance is strongly associated with insect cold tolerance in the field: a seasonal study of Drosophila subobscura.

PubMed

MacMillan, Heath A; Schou, Mads F; Kristensen, Torsten N; Overgaard, Johannes

2016-05-01

There is interest in pinpointing genes and physiological mechanisms explaining intra- and interspecific variations in cold tolerance, because thermal tolerance phenotypes strongly impact the distribution and abundance of wild animals. Laboratory studies have highlighted that the capacity to preserve water and ion homeostasis is linked to low temperature survival in insects. It remains unknown, however, whether adaptive seasonal acclimatization in free-ranging insects is governed by the same physiological mechanisms. Here, we test whether cold tolerance in field-caught Drosophila subobscura is high in early spring and lower during summer and whether this transition is associated with seasonal changes in the capacity of flies to preserve water and ion balance during cold stress. Indeed, flies caught during summer were less cold tolerant, and exposure of these flies to sub-zero temperatures caused a loss of haemolymph water and increased the concentration of K(+) in the haemolymph (as in laboratory-reared insects). This pattern of ion and water balance disruption was not observed in more cold-tolerant flies caught in early spring. Thus, we here provide a field verification of hypotheses based on laboratory studies and conclude that the ability to maintain ion homeostasis is important for the ability of free-ranging insects to cope with chilling. © 2016 The Author(s).

Chitosan-co-Hyaluronic acid porous cryogels and their application in tissue engineering.

PubMed

Kutlusoy, Tuğçe; Oktay, Burcu; Apohan, Nilhan Kayaman; Süleymanoğlu, Mediha; Kuruca, Serap Erdem

2017-10-01

In this work, the usability of chitosan-co-hyaluronic acid cryogels as a tissue-engineering scaffold was investigated. Chitosan-co-hyaluronic acid cryogels were synthesized at subzero temperature. Cryogels which were composed of various compositions of chitosan and hyaluronic acid (0, 10, 20, 30 and 50wt% hyaluronic acid) was prepared. Morphological studies showed that the macroporous cryogels have been developed with 90-95% porosity. Particularly, the mechanical and biomaterial property of pure chitosan was improved by making copolymer with hyaluronic acid in different concentration. The MTT cell viability results demonstrated that the cryogels have no significant cytotoxicity effect on 3T3 fibroblast and SAOS-2 cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Microorganisms from Permafrost Viable and Detectable by 16SRNA Analysis: A Model for Mars

NASA Technical Reports Server (NTRS)

Tsapin, A. I.; McDonald, G. D.; Andrews, M.; Bhartia, R.; Douglas, S.; Gilichinsky, D.

1999-01-01

Preliminary studies of Arctic and Antarctic permafrost have shown that this environment harbors microorganisms which can be isolated in pure culture, and that these organisms can survive for a long period of time (up to 20 Ma) in permafrost. It is believed that the permanent subzero temperatures in permafrost and ice environments are the main parameters ensuring the longevity of microbes. In this project we studied permafrost cores from different areas of the Siberian Arctic and Antarctic, with ages from several thousand years up to several millions years (Ma). In general, Antarctic permafrost has a higher sand content, while Siberian permafrost has a texture more characteristic of clay or normal soil. Additional information is contained in the original extended abstract.

Winter cold-tolerance thresholds in field-grown Miscanthus hybrid rhizomes

PubMed Central

Peixoto, Murilo de Melo; Friesen, Patrick Calvin; Sage, Rowan F.

2015-01-01

The cold tolerance of winter-dormant rhizomes was evaluated in diploid, allotriploid, and allotetraploid hybrids of Miscanthus sinensis and Miscanthus sacchariflorus grown in a field setting. Two artificial freezing protocols were tested: one lowered the temperature continuously by 1°C h–1 to the treatment temperature and another lowered the temperature in stages of 24h each to the treatment temperature. Electrolyte leakage and rhizome sprouting assays after the cold treatment assessed plant and tissue viability. Results from the continuous-cooling trial showed that Miscanthus rhizomes from all genotypes tolerated temperatures as low as –6.5 °C; however, the slower, staged-cooling procedure enabled rhizomes from two diploid lines to survive temperatures as low as –14 °C. Allopolyploid genotypes showed no change in the lethal temperature threshold between the continuous and staged-cooling procedure, indicating that they have little ability to acclimate to subzero temperatures. The results demonstrated that rhizomes from diploid Miscanthus lines have superior cold tolerance that could be exploited to improve performance in more productive polyploid lines. With expected levels of soil insulation, low winter air temperatures should not harm rhizomes of tolerant diploid genotypes of Miscanthus in temperate to sub-boreal climates (up to 60°N); however, the observed winter cold in sub-boreal climates could harm rhizomes of existing polyploid varieties of Miscanthus and thus reduce stand performance. PMID:25788733

Microbial survival strategies in ancient permafrost: insights from metagenomics

USGS Publications Warehouse

Mackelprang, Rachel; Burkert, Alexander; Haw, Monica; Mahendrarajah, Tara; Conaway, Christopher H.; Douglas, Thomas A.; Waldrop, Mark P.

2017-01-01

In permafrost (perennially frozen ground) microbes survive oligotrophic conditions, sub-zero temperatures, low water availability and high salinity over millennia. Viable life exists in permafrost tens of thousands of years old but we know little about the metabolic and physiological adaptations to the challenges presented by life in frozen ground over geologic time. In this study we asked whether increasing age and the associated stressors drive adaptive changes in community composition and function. We conducted deep metagenomic and 16 S rRNA gene sequencing across a Pleistocene permafrost chronosequence from 19 000 to 33 000 years before present (kyr). We found that age markedly affected community composition and reduced diversity. Reconstruction of paleovegetation from metagenomic sequence suggests vegetation differences in the paleo record are not responsible for shifts in community composition and function. Rather, we observed shifts consistent with long-term survival strategies in extreme cryogenic environments. These include increased reliance on scavenging detrital biomass, horizontal gene transfer, chemotaxis, dormancy, environmental sensing and stress response. Our results identify traits that may enable survival in ancient cryoenvironments with no influx of energy or new materials.

Microbial survival strategies in ancient permafrost: insights from metagenomics.

PubMed

Mackelprang, Rachel; Burkert, Alexander; Haw, Monica; Mahendrarajah, Tara; Conaway, Christopher H; Douglas, Thomas A; Waldrop, Mark P

2017-10-01

In permafrost (perennially frozen ground) microbes survive oligotrophic conditions, sub-zero temperatures, low water availability and high salinity over millennia. Viable life exists in permafrost tens of thousands of years old but we know little about the metabolic and physiological adaptations to the challenges presented by life in frozen ground over geologic time. In this study we asked whether increasing age and the associated stressors drive adaptive changes in community composition and function. We conducted deep metagenomic and 16 S rRNA gene sequencing across a Pleistocene permafrost chronosequence from 19 000 to 33 000 years before present (kyr). We found that age markedly affected community composition and reduced diversity. Reconstruction of paleovegetation from metagenomic sequence suggests vegetation differences in the paleo record are not responsible for shifts in community composition and function. Rather, we observed shifts consistent with long-term survival strategies in extreme cryogenic environments. These include increased reliance on scavenging detrital biomass, horizontal gene transfer, chemotaxis, dormancy, environmental sensing and stress response. Our results identify traits that may enable survival in ancient cryoenvironments with no influx of energy or new materials.

Microbial survival strategies in ancient permafrost: insights from metagenomics

PubMed Central

Mackelprang, Rachel; Burkert, Alexander; Haw, Monica; Mahendrarajah, Tara; Conaway, Christopher H; Douglas, Thomas A; Waldrop, Mark P

2017-01-01

In permafrost (perennially frozen ground) microbes survive oligotrophic conditions, sub-zero temperatures, low water availability and high salinity over millennia. Viable life exists in permafrost tens of thousands of years old but we know little about the metabolic and physiological adaptations to the challenges presented by life in frozen ground over geologic time. In this study we asked whether increasing age and the associated stressors drive adaptive changes in community composition and function. We conducted deep metagenomic and 16 S rRNA gene sequencing across a Pleistocene permafrost chronosequence from 19 000 to 33 000 years before present (kyr). We found that age markedly affected community composition and reduced diversity. Reconstruction of paleovegetation from metagenomic sequence suggests vegetation differences in the paleo record are not responsible for shifts in community composition and function. Rather, we observed shifts consistent with long-term survival strategies in extreme cryogenic environments. These include increased reliance on scavenging detrital biomass, horizontal gene transfer, chemotaxis, dormancy, environmental sensing and stress response. Our results identify traits that may enable survival in ancient cryoenvironments with no influx of energy or new materials. PMID:28696425

Studies of evolutionary temperature adaptation: muscle function and locomotor performance in Antarctic fish.

PubMed

Franklin, C E

1998-09-01

1. Studies of evolutionary temperature adaptation of muscle and locomotor performance in fish are reviewed with a focus on the Antarctic fauna living at subzero temperatures. 2. Only limited data are available to compare the sustained and burst swimming kinematics and performance of Antarctic, temperate and tropical species. Available data indicate that low temperatures limit maximum swimming performance and this is especially evident in fish larvae. 3. In a recent study, muscle performance in the Antarctic rock cod Notothenia coriiceps at 0 degree C was found to be sufficient to produce maximum velocities during burst swimming that were similar to those seen in the sculpin Myoxocephalus scorpius at 10 degrees C, indicating temperature compensation of muscle and locomotor performance in the Antarctic fish. However, at 15 degrees C, sculpin produce maximum swimming velocities greater than N. coriiceps at 0 degree C. 4. It is recommended that strict hypothesis-driven investigations using ecologically relevant measures of performance are undertaken to study temperature adaptation in Antarctic fish. Recent detailed phylogenetic analyses of the Antarctic fish fauna and their temperate relatives will allow a stronger experimental approach by helping to separate what is due to adaptation to the cold and what is due to phylogeny alone.

Imaging cold-induced vasodynamic behaviour in skin using OCT for microangiography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Casper, Malte; Schulz-Hildebrandt, Hinnerk; Evers, Michael; Nguyen, Cuc; Birngruber, Reginald; Hüttmann, Gereon; Manstein, Dieter

2017-02-01

In dermatology the reflexes of vasoconstriction and vasodilation are known as important mechanisms of thermoregulation of the inner body. Imaging the physiology of microvasculature of the skin with high spatial resolution in three dimensions while reacting to changes in temperature is crucial for understanding the complex processes of vasodynamics, which result in constriction and dilation of vessels. However, previous studies using Laser-Doppler flowmetry and -imaging could not provide reliable angiographic images which allow to quantify changes in blood vessel diameter. Here, we report a different approach for angiographic imaging of microvasculature of a anaesthetized rodent model using speckle variance optical coherence tomography (svOCT) during and after localized cooling. Therefore a commercial OCT with a center wavelength of 1.3 μm and a spatial resolution of 13µm was used in combination with a custom built cooling device to image such reflexes at the mouse ear pinna and dorsal skinfold. Cooling was applied in steps of 2-5° C starting at the baseline temperature of 27° C down to -10° C. To our surprise and in contrast to the general opinion in literature, we were able to observe that the majority of vessels with a diameter larger than 20 μm maintain perfused with a constant diameter when the tissue is cooled from baseline to subzero temperatures. However, vasoconstriction was observed very rarely and only in veins, which led to their occlusion. The results of this experiment lead us to reconsider essential aspects of previous understanding of temperature-induced vasodynamics in cutaneous microvasculature.

Designed synergetic effect of electrolyte additives to improve interfacial chemistry of MCMB electrode in propylene carbonate-based electrolyte for enhanced low and room temperature performance.

PubMed

Wotango, Aselefech Sorsa; Su, Wei-Nien; Haregewoin, Atetegeb Meazah; Chen, Hung-Ming; Cheng, Ju-Hsiang; Lin, Ming-Hsien; Wang, Chia-Hsin; Hwang, Bing-Joe

2018-05-09

The performance of lithium ion batteries rapidly falls at lower temperatures due to decreasing conductivity of electrolytes and Solid Electrolyte Interphase (SEI) on graphite anode. Hence, it limits the practical use of lithium ion batteries at sub-zero temperatures and also affects the development of lithium ion batteries for widespread applications. The SEI formed on the graphite surface is very influential in determining the performance of the battery. Herein, a new electrolyte additive, 4-Chloromethyl-1,3,2-dioxathiolane-2-oxide (CMDO), is prepared to improve the properties of commonly used electrolyte constituents - ethylene carbonate (EC), and fluoroethylene carbonate (FEC). The formation of an efficient passivation layer in propylene carbonate (PC) -based electrolyte for MCMB electrode was investigated. The addition of CMDO resulted in a much less irreversible capacity loss and induces thin SEI formation. However, the combination of the three additives played a key role to enhance reversible capacity of MCMB electrode at lower or ambient temperature. The electrochemical measurement analysis showed that the SEI formed from a mixture of the three additives gave better intercalation-deintercalation of lithium ions.

Investigation of the reaction of 5Al-2.5Sn titanium with hydrogen at subzero temperature

NASA Technical Reports Server (NTRS)

Williams, D. N.; Wood, R. A.

1972-01-01

An investigation of the effect of temperature on the surface hydriding reaction of 5Al-2.5Sn titanium exposed to hydrogen at 250 psig was made. The temperature range studied extended from 160 F to -160 F. Reaction conditions were controlled so as to expose a vacuum-cleaned, oxide-free alloy surface to an ultrapure hydrogen atmosphere. Reaction times up to 1458 hours were studied. The hydriding reaction was extremely sensitive to experimental variables and the reproducibility of reaction behavior was poor. However, it was demonstrated that the reaction proceeded quite rapidly at 160 F; as much as 1 mil surface hydriding being observed after exposure for 162 hours. The amount of hydriding appeared to decrease with decreasing temperature at 75 F, -36 F, and -76 F. No surface hydriding was detected either by vacuum fusion analysis or by metallographic examination after exposure for 1458 hours at -110 F or -160 F. Tensile properties were unaffected by surface hydriding of the severity developed in this program (up to 1 mil thick) as determined by slow strain rate testing of hydrided sheet tensile samples.

Thermal Destabilization of Collagen Matrix Hierarchical Structure by Freeze/Thaw

PubMed Central

Ozcelikkale, Altug; Han, Bumsoo

2016-01-01

This study aims to characterize and understand the effects of freezing on collagen structures and functionality. Specifically, thermodynamic destabilization of collagen at molecular- and fibril-levels by combination of low temperatures and freezing were experimentally characterized using modulated differential scanning calorimetry. In order to delineate the effects of sub-zero temperature and water-ice phase change, we hypothesized that the extent of destabilization can be determined based on post-thaw heat induced thermal denaturation of collagen. It is found that thermal denaturation temperature of collagen in hydrogel decreases by 1.4–1.6°C after freeze/thaw while no such decrease is observed in the case of molecular solution. The destabilization is predominantly due to ice formation. Exposure to low temperatures in the absence of ice has only minimal effect. Calorimetry measurements combined with morphological examination of collagen matrices by scanning electron microscopy suggest that freezing results in destabilization of collagen fibrils due to expansion of intrafibrillar space by ice formation. This fibril-level damage can be alleviated by use of cryoprotectant DMSO at concentrations as low as 0.5 M. A theoretical model explaining the change in collagen post-thaw thermal stability by freezing-induced fibril expansion is also proposed. PMID:26765741

Rapid tenderisation of lamb M. longissimus with very fast chilling depends on rapidly achieving sub-zero temperatures.

PubMed

Jacob, Robin; Rosenvold, Katja; North, Michael; Kemp, Robert; Warner, Robyn; Geesink, Geert

2012-09-01

A study was undertaken to determine whether variations within the defined temperature-by-time profile for very fast chilling (VFC), might explain variations in tenderness found with VFC. Loins from 32 lambs were subjected to one of five cooling regimes; defined by the average temperature between the meat surface and centre reached at a specific time post mortem. These were: -0.3 °C at 22 h (Control), 2.6 °C at 1.5 h (Fast(supra-zero)), 0.7 °C at 5.5 h (Slow(supra-zero)), -1.6 °C at 1.5 h (Fast(sub-zero)) and -2.3 °C at 5.5 h (Slow(sub-zero)), respectively. Shear force values considered very tender by consumers (less than 50 N, MIRINZ tenderometer) were found 2 days post mortem in Fast(sub-zero) loins only. Both time and temperature at the end of the cooling period contributed to variations in shear force. To achieve low shear force, the loins needed to be cooled to less than 0 °C at 1.5 h post mortem. Copyright © 2012 Elsevier Ltd. All rights reserved.

Characterization of the ice nucleation activity of an airborne Penicillium species

NASA Astrophysics Data System (ADS)

Yordanova, Petya; Hill, Thomas C. J.; Pummer, Bernhard G.; Franc, Gary D.; Pöschl, Ulrich; Fröhlich-Nowoisky, Janine

2016-04-01

Microorganisms are ubiquitous both on and above the Earth. Several bacterial and fungal spe-cies are the focus of atmospheric studies due to their ability to trigger ice formation at high subzero temperatures. Thus, they have potential to modify cloud albedo, lifetime and precipita-tion, and ultimately the hydrological cycle. Several fungal strains have already been identified as possessing ice nucleation (IN) activity, and recent studies have shown that IN active fungi are present in the cultivable community of air and soil samples [1, 2]. However, the abundance, diversity, and sources of fungal ice nuclei in the atmosphere are still poorly characterized. In this study, fungal colonies obtained from air samples were screened for IN activity in the droplet-freezing assay described in Fröhlich-Nowoisky et al., 2015 [2]. Out of 128 tested iso-lates, two were found to catalyze ice formation at temperatures up to -4°C. By DNA analysis, both isolates were classified as Penicillium spp. The freezing activity of both was further char-acterized after different filtration, heat, and enzymatic treatments in the temperature range from -4°C to -15°C. Preliminary results show that a proteinaceous compound is responsible for the IN activity. Furthermore, ongoing experiments indicate that the activity is associated only with the hyphae. [1] Huffman, et al. (2013): Atmos. Chem. Phys., 13, 6151-6164. [2] Fröhlich-Nowoisky et al. (2015): Biogeosciences, 12: 1057-1071.

Kinetics of water loss and the likelihood of intracellular freezing in mouse ova

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazur, P.; Rall, W.F.; Leibo, S.P.

To avoid intracellular freezing and its usually lethal consequences, cells must lose their freezable water before reaching their ice-nucleation temperature. One major factor determining the rate of water loss is the temperature dependence of water permeability, L/sub p/ (hydraulic conductivity). Because of the paucity of water permeability measurements at subzero temperatures, that temperature dependence has usually been extrapolated from above-zero measurements. The extrapolation has often been based on an exponential dependence of L/sub p/ on temperature. This paper compares the kinetics of water loss based on that extrapolation with that based on an Arrhenius relation between L/sub p/ and temperature,more » and finds substantial differences below -20 to -25/sup 0/C. Since the ice-nucleation temperature of mouse ova in the cryoprotectants DMSO and glycerol is usually below -30/sup 0/C, the Arrhenius form of the water-loss equation was used to compute the extent of supercooling in ova cooled at rates between 1 and 8/sup 0/C/min and the consequent likelihood of intracellular freezing. The predicted likelihood agrees well with that previously observed. The water-loss equation was also used to compute the volumes of ova as a function of cooling rate and temperature. The computed cell volumes agree qualitatively with previously observed volumes, but differed quantitatively. 25 references, 5 figures, 3 tables.« less

Soil carbon distribution in Alaska in relation to soil-forming factors

USGS Publications Warehouse

Johnson, K.D.; Harden, J.; McGuire, A.D.; Bliss, N.B.; Bockheim, James G.; Clark, M.R.; Nettleton-Hollingsworth, T.; Jorgenson, M.T.; Kane, E.S.; Mack, M.; O'Donnell, J.; Ping, C.-L.; Schuur, E.A.G.; Turetsky, M.R.; Valentine, D.W.

2011-01-01

The direction and magnitude of soil organic carbon (SOC) changes in response to climate change remain unclear and depend on the spatial distribution of SOC across landscapes. Uncertainties regarding the fate of SOC are greater in high-latitude systems where data are sparse and the soils are affected by sub-zero temperatures. To address these issues in Alaska, a first-order assessment of data gaps and spatial distributions of SOC was conducted from a recently compiled soil carbon database. Temperature and landform type were the dominant controls on SOC distribution for selected ecoregions. Mean SOC pools (to a depth of 1-m) varied by three, seven and ten-fold across ecoregion, landform, and ecosystem types, respectively. Climate interactions with landform type and SOC were greatest in the uplands. For upland SOC there was a six-fold non-linear increase in SOC with latitude (i.e., temperature) where SOC was lowest in the Intermontane Boreal compared to the Arctic Tundra and Coastal Rainforest. Additionally, in upland systems mineral SOC pools decreased as climate became more continental, suggesting that the lower productivity, higher decomposition rates and fire activity, common in continental climates, interacted to reduce mineral SOC. For lowland systems, in contrast, these interactions and their impacts on SOC were muted or absent making SOC in these environments more comparable across latitudes. Thus, the magnitudes of SOC change across temperature gradients were non-uniform and depended on landform type. Additional factors that appeared to be related to SOC distribution within ecoregions included stand age, aspect, and permafrost presence or absence in black spruce stands. Overall, these results indicate the influence of major interactions between temperature-controlled decomposition and topography on SOC in high-latitude systems. However, there remains a need for more SOC data from wetlands and boreal-region permafrost soils, especially at depths > 1 m in order to fully understand the effects of climate on soil carbon in Alaska.

Bacterial Ice Crystal Controlling Proteins

PubMed Central

Lorv, Janet S. H.; Rose, David R.; Glick, Bernard R.

2014-01-01

Across the world, many ice active bacteria utilize ice crystal controlling proteins for aid in freezing tolerance at subzero temperatures. Ice crystal controlling proteins include both antifreeze and ice nucleation proteins. Antifreeze proteins minimize freezing damage by inhibiting growth of large ice crystals, while ice nucleation proteins induce formation of embryonic ice crystals. Although both protein classes have differing functions, these proteins use the same ice binding mechanisms. Rather than direct binding, it is probable that these protein classes create an ice surface prior to ice crystal surface adsorption. Function is differentiated by molecular size of the protein. This paper reviews the similar and different aspects of bacterial antifreeze and ice nucleation proteins, the role of these proteins in freezing tolerance, prevalence of these proteins in psychrophiles, and current mechanisms of protein-ice interactions. PMID:24579057

Bacterial ice crystal controlling proteins.

PubMed

Lorv, Janet S H; Rose, David R; Glick, Bernard R

2014-01-01

Across the world, many ice active bacteria utilize ice crystal controlling proteins for aid in freezing tolerance at subzero temperatures. Ice crystal controlling proteins include both antifreeze and ice nucleation proteins. Antifreeze proteins minimize freezing damage by inhibiting growth of large ice crystals, while ice nucleation proteins induce formation of embryonic ice crystals. Although both protein classes have differing functions, these proteins use the same ice binding mechanisms. Rather than direct binding, it is probable that these protein classes create an ice surface prior to ice crystal surface adsorption. Function is differentiated by molecular size of the protein. This paper reviews the similar and different aspects of bacterial antifreeze and ice nucleation proteins, the role of these proteins in freezing tolerance, prevalence of these proteins in psychrophiles, and current mechanisms of protein-ice interactions.

On the mechanism of injury to slowly frozen erythrocytes.

PubMed Central

Pegg, D E; Diaper, M P

1988-01-01

When cells are frozen slowly in aqueous suspensions, the solutes in the suspending solution concentrate as the amount of ice increases; the cells undergo osmotic dehydration and are sequestered in ever-narrowing liquid-filled channels. Cryoprotective solutes, such as glycerol, reduce the amount of ice that forms at any specified subzero temperature, thereby controlling the buildup in concentration of those other solutes present, as well as increasing the volume of the channels that remain to accommodate the cells. It has generally been thought that freezing injury is mediated by the increase in electrolyte concentration in the milieu surrounding the cells, rather than reduction of temperature or any direct action of ice. In this study we have frozen human erythrocytes in isotonic solutions of sodium chloride and glycerol and have demonstrated a correlation between the extent of damage at specific subzero temperatures, and that caused by the action at 0 degrees C of solutions having the same composition as those produced by freezing. The cell lysis observed increased directly with glycerol concentration, both in the freezing experiments and when the cells were exposed to corresponding solutions at 0 degrees C, showing that the concentration of sodium chloride alone is not sufficient to account quantitatively for the damage observed. We then studied the effect of freezing in anisotonic solutions to break the fixed relationship between solute concentration and the volume of the unfrozen fraction, as described by Mazur, P., W. F. Rall, and N. Rigopoulos (1981. Biophys. J. 653-675). We confirmed their experimental findings, but we explain them differently. We ascribe the apparently dominant effect of the unfrozen fraction to the fact that the cells were frozen in, and returned to, anisotonic solutions in which their volume was either less than, or greater than, their physiological volume. When similar cell suspensions were subjected to a similar cycle of increase and then decrease in solution strength, but in the absence of ice (at 20 degrees C), a similar pattern of hemolysis was observed. We conclude that freezing injury to human erythrocytes is due solely to changes that occur in the composition of their surrounding milieu, and is most probably mediated by a temporary leak in the plasma membrane that occurs during the thawing (reexpansion) phase. PMID:3207835

Winter cold-tolerance thresholds in field-grown Miscanthus hybrid rhizomes.

PubMed

Peixoto, Murilo de Melo; Friesen, Patrick Calvin; Sage, Rowan F

2015-07-01

The cold tolerance of winter-dormant rhizomes was evaluated in diploid, allotriploid, and allotetraploid hybrids of Miscanthus sinensis and Miscanthus sacchariflorus grown in a field setting. Two artificial freezing protocols were tested: one lowered the temperature continuously by 1°C h(-1) to the treatment temperature and another lowered the temperature in stages of 24h each to the treatment temperature. Electrolyte leakage and rhizome sprouting assays after the cold treatment assessed plant and tissue viability. Results from the continuous-cooling trial showed that Miscanthus rhizomes from all genotypes tolerated temperatures as low as -6.5 °C; however, the slower, staged-cooling procedure enabled rhizomes from two diploid lines to survive temperatures as low as -14 °C. Allopolyploid genotypes showed no change in the lethal temperature threshold between the continuous and staged-cooling procedure, indicating that they have little ability to acclimate to subzero temperatures. The results demonstrated that rhizomes from diploid Miscanthus lines have superior cold tolerance that could be exploited to improve performance in more productive polyploid lines. With expected levels of soil insulation, low winter air temperatures should not harm rhizomes of tolerant diploid genotypes of Miscanthus in temperate to sub-boreal climates (up to 60°N); however, the observed winter cold in sub-boreal climates could harm rhizomes of existing polyploid varieties of Miscanthus and thus reduce stand performance. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Cold tolerance of first-instar nymphs of the Australian plague locust, Chortoicetes terminifera.

PubMed

Woodman, James D

2010-04-01

The cold tolerance of first-instar nymphs of the Australian plague locust, Chortoicetes terminifera, was examined using measures of total body water content, supercooling point and mortality for a range of sub-zero temperature exposure regimes. The supercooling points for starved and fed nymphs were -13.1+/-0.9 and -12.6+/-1.6 degrees C, and freezing caused complete mortality. Above these temperatures, nymphs were cold tolerant to different degrees based on whether they were starved or given access to food and water for 24h prior to exposure. The rate of cooling also had a significant effect on mortality. Very rapid cooling to -7 degrees C caused 84 and 87% mortality for starved and fed nymphs respectively, but this significantly decreased for starved nymphs if temperature declined by more ecologically realistic rates of 0.5 and 0.1 degrees C min(-1). These results are indicative of a rapid cold hardening response and are discussed in terms of the likely effects of cold nights and frost on first-instar nymphal survival in the field. Crown Copyright (c) 2009. Published by Elsevier Ltd. All rights reserved.

Effect of long term chilled (up to 5 weeks) then frozen (up to 12 months) storage at two different sub-zero holding temperatures on beef: 3. Protein structure degradation and a marker of protein oxidation.

PubMed

Holman, Benjamin W B; Coombs, Cassius E O; Morris, Stephen; Kerr, Matthew J; Hopkins, David L

2018-05-01

Different chilled (~0.1 °C for up to 5 weeks) then frozen storage (up to 12 months) combinations and two frozen storage holding temperatures (-12 °C and -18 °C) effects on beef M. longissimus lumborum (LL) protein structure degradation and a marker of protein oxidation were tested. Particle size (PS) analysis and protein solubility results found storage combination effects on protein degradation to be significant (P < 0.05), although the influence of frozen holding temperatures was negligible. LL carbonyl, and nitrate and nitrite content responses were variable and yet broadly reflected an increased incidence of protein oxidation across increasing chilled storage and ensuing frozen storage periods - this aspect meriting future exploration. Total myoglobin content and the estimated myoglobin redox fractions (metmyoglobin, deoxymyoglobin, and oxymyoglobin) were also subject to storage treatment. These findings demonstrate the capacity for beef storage selection (chilled-then-frozen) to manage compositional protein changes and its implications on sensory quality traits across comparative 'long term' durations. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Effect of long term chilled (up to 5weeks) then frozen (up to 12months) storage at two different sub-zero holding temperatures on beef: 1. Meat quality and microbial loads.

PubMed

Holman, Benjamin W B; Coombs, Cassius E O; Morris, Stephen; Kerr, Matthew J; Hopkins, David L

2017-11-01

Beef loins (LL) stored under different chilled-then-frozen storage combinations (up to 5 and 52weeks, respectively) and two frozen holding temperatures were evaluated for microbial load and meat quality parameters. We found holding temperature effects to be negligible, which suggest -12°C could deliver comparable quality LL to -18°C across these same storage periods. Meat quality parameters varied significantly, but when compared to existing consumer thresholds these may not be perceptible, colour being the exception which proved unacceptable, earlier into retail display when either chilled and subsequent frozen storage periods were increased. There was insufficient detection of key spoilage microbes to allow for statistical analysis, potentially due to the hygienic and commercially representative LL source, although variation in water activity, glycogen content, pH and other moisture parameters conducive to microbial proliferation were influenced by chilled-then-frozen storage. These outcomes could be applied to defining storage thresholds that assure beef quality within export networks, leveraging market access, and improving product management. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Effect of long term chilled (up to 5weeks) then frozen (up to 12months) storage at two different sub-zero holding temperatures on beef: 2. Lipid oxidation and fatty acid profiles.

PubMed

Holman, Benjamin W B; Coombs, Cassius E O; Morris, Stephen; Bailes, Kristy; Hopkins, David L

2018-02-01

Lipid oxidation and fatty acid (FA) profiles were evaluated for beef M. longissimus lumborum (LL) stored under different chilled-then-frozen storage combinations (up to 5 and 52weeks, respectively) and two frozen holding temperatures (-12°C and -18°C). FA profile variation was observed, with increasing frozen storage periods resulting in unsaturated FA levels declining as saturated FA levels increased. Polyunsaturated and health claimable FA levels also tended to decline with increasing chilled storage period, albeit insignificant within the constraints of the experimental design. Peroxidase activity, TBARS and oxidation-reduction potential analyses reflected these FA changes. These, when compared against existing consumer thresholds, suggest a perceptible detraction from LL held under long-term frozen storage durations that are less evident earlier as dependent on the preceding chilled storage period. Negligible impact of frozen storage holding temperatures was observed on measured traits. These results suggest long-term chilled-then-frozen storage can influence beef lipid stability, healthy FA profile and therefore the healthiness of beef. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Search for extraterrestrial life using chiral molecules: mandelate racemase as a test case.

PubMed

Thaler, Tracey L; Gibbs, Phillip R; Trebino, Rick P; Bommarius, Andreas S

2006-12-01

We have investigated an enzymatic racemization reaction as a marker for extraterrestrial life, which resulted in a change in optical rotation of a mandelic acid over time, as measured by polarimetry. Mandelate racemase was active in aqueous buffer in a temperature range between 0 degrees C and 70 degrees C and also in concentrated ammonium salt solutions and water-in-oil microemulsions in a temperature range between -30 degrees C and 60-70 degrees C; however, the enzyme was not active in several organic cryosolvents. Thus, we have demonstrated that concentrated ammonium salt solutions and water-in-oil microemulsions, both of which are able to form on extraterrestrial planets and moons in the presence of liquid water, are suitable media for enzyme reactions at subzero temperatures. Kinetic data for the mandelate racemase reaction obtained by polarimetry, while reproducible and internally consistent, differed significantly from several sets of data obtained previously by other methods such as chromatography and hydrogen-deuterium exchange. However, we conclude that reactions yielding a polarimetric signal, such as the racemizations employed in this work, are suitable mechanisms by which to utilize a change in chirality over time as a tool to detect signs of life.

Spores of most common airborne fungi reveal no ice nucleation activity

NASA Astrophysics Data System (ADS)

Pummer, B. G.; Atanasova, L.; Bauer, H.; Bernardi, J.; Druzhinina, I. S.; Grothe, H.

2013-06-01

Fungal spores are ubiquitous biological aerosols, which are considered to show ice nucleation (IN) activity. In this study the respective IN activity was tested in oil emulsion in the immersion freezing mode. The focus was laid on species of economical, ecological or sanitary significance. For the first time, not only common moulds, but also edible mushrooms (Basidiomycota, Agaricomycetes) were investigated, as they contribute massively to the total amount of fungal spores in the atmosphere. Only Fusarium avenaceum showed freezing events at low subzero-temperatures, while the other investigated fungal spores showed no significant IN activity. Furthermore, we selected a set of fungal strains from different sites and exposed them to occasional freezing stress during cultivation. Although the total protein expression was altered by this treatment, it had no significant impact on the IN activity.

Metabolic Response of Soil Microorganisms to Frost: A New Perspective from Position-specific 13C Labeling

NASA Astrophysics Data System (ADS)

Bore, E. K.; Apostel, C.; Halicki, S.; Dippold, M. A.; Kuzyakov, Y.

2016-12-01

Cold adapted organisms and their biomolecules have received considerable attention in the last few decades, particularly in light of the perceived biotechnological potential. Mostly, these studies are based on pure isolated cultures from permafrost or permafrost samples with inherently adapted microbes. However, microbial activities in agricultural soils that are predominantly exposed to freeze conditions during winter in temperate ecosystems remain unclear. To analyze microbial metabolism at low soil temperatures, isotopomeres of position-specifically 13C labeled glucose were incubated at three temperature; 5 (control), -5 -20 oC. Soils were sampled after 1, 3 and 10 days (and after 30 days for samples at -20 °C). 13C was quantifed in CO2, bulk soil, microbial biomass and dissolved organic carbon (DOC). Highest 13C recovery in CO2 was obtained from C-1 position in control soil. Consequently, metabolic activity was dominated by pentose phosphate pathway at 5 °C. In contrast, metabolic behaviors switched towards a preferential respiration of the glucose C-4 position at -5 and -20 °C. High 13C recovery from C-4 position confirms previous studies suggesting that fermentation increases at subzero temperature. A 3-fold higher 13C recovery in microbial biomass at -5 °C than under control conditions points towards synthesis of intracellular antifreeze metabolites such as glycerol and ethanol and it is consistent with fermentative metabolism. A 5-fold higher 13C in bulk soil than microbial biomass at -20 °C does not reflect non-metabolized glucose because 13C recovery in DOC was less than 0.4% at day 1. Therefore, high 13C recovery in bulk soil at -20 °C was attributed to extracellular metabolites secreted to overcome frost. The shift in antifreeze mechanisms with temperature was brought about by shift in microbial community structure as indicated by incorporation into 13C into PLFA which was 2-fold higher in gram negative bacteria under control than frozen conditions, but inverted in gram positives. The results confirm that catabolic and anabolic processes continue under frozen conditions, but, mechanisms differ with temperature. This information is not only useful in modelling C dynamics in permafrost, but also in food industry where shelf-life depends on frozen conditions. Cold adapted organisms and their biomolecules have received considerable attention in the last few decades, particularly in light of the perceived biotechnological potential. Mostly, these studies are based on pure isolated cultures from permafrost or permafrost samples with inherently adapted microbes. However, microbial activities in agricultural soils that are predominantly exposed to freeze conditions during winter in temperate ecosystems remain unclear. To analyze microbial metabolism at low soil temperatures, isotopomeres of position-specifically 13C labeled glucose were incubated at three temperature; 5 (control), -5 -20 oC. Soils were sampled after 1, 3 and 10 days (and after 30 days for samples at -20 °C). 13C was quantifed in CO2, bulk soil, microbial biomass and dissolved organic carbon (DOC). Highest 13C recovery in CO2 was obtained from C-1 position in control soil. Consequently, metabolic activity was dominated by pentose phosphate pathway at 5 °C. In contrast, metabolic behaviors switched towards a preferential respiration of the glucose C-4 position at -5 and -20 °C. High 13C recovery from C-4 position confirms previous studies suggesting that fermentation increases at subzero temperature. A 3-fold higher 13C recovery in microbial biomass at -5 °C than under control conditions points towards synthesis of intracellular antifreeze metabolites such as glycerol and ethanol and it is consistent with fermentative metabolism. A 5-fold higher 13C in bulk soil than microbial biomass at -20 °C does not reflect non-metabolized glucose because 13C recovery in DOC was less than 0.4% at day 1. Therefore, high 13C recovery in bulk soil at -20 °C was attributed to extracellular metabolites secreted to overcome frost. The shift in antifreeze mechanisms with temperature was brought about by shift in microbial community structure as indicated by incorporation into 13C into PLFA which was 2-fold higher in gram negative bacteria under control than frozen conditions, but inverted in gram positives. The results confirm that catabolic and anabolic processes continue under frozen conditions, but, mechanisms differ with temperature. This information is not only useful in modelling C dynamics in permafrost, but also in food industry where shelf-life depends on frozen conditions.

Systematic size study of an insect antifreeze protein and its interaction with ice.

PubMed

Liu, Kai; Jia, Zongchao; Chen, Guangju; Tung, Chenho; Liu, Ruozhuang

2005-02-01

Because of their remarkable ability to depress the freezing point of aqueous solutions, antifreeze proteins (AFPs) play a critical role in helping many organisms survive subzero temperatures. The beta-helical insect AFP structures solved to date, consisting of multiple repeating circular loops or coils, are perhaps the most regular protein structures discovered thus far. Taking an exceptional advantage of the unusually high structural regularity of insect AFPs, we have employed both semiempirical and quantum mechanics computational approaches to systematically investigate the relationship between the number of AFP coils and the AFP-ice interaction energy, an indicator of antifreeze activity. We generated a series of AFP models with varying numbers of 12-residue coils (sequence TCTxSxxCxxAx) and calculated their interaction energies with ice. Using several independent computational methods, we found that the AFP-ice interaction energy increased as the number of coils increased, until an upper bound was reached. The increase of interaction energy was significant for each of the first five coils, and there was a clear synergism that gradually diminished and even decreased with further increase of the number of coils. Our results are in excellent agreement with the recently reported experimental observations.

Systematic Size Study of an Insect Antifreeze Protein and Its Interaction with Ice

PubMed Central

Liu, Kai; Jia, Zongchao; Chen, Guangju; Tung, Chenho; Liu, Ruozhuang

2005-01-01

Because of their remarkable ability to depress the freezing point of aqueous solutions, antifreeze proteins (AFPs) play a critical role in helping many organisms survive subzero temperatures. The β-helical insect AFP structures solved to date, consisting of multiple repeating circular loops or coils, are perhaps the most regular protein structures discovered thus far. Taking an exceptional advantage of the unusually high structural regularity of insect AFPs, we have employed both semiempirical and quantum mechanics computational approaches to systematically investigate the relationship between the number of AFP coils and the AFP-ice interaction energy, an indicator of antifreeze activity. We generated a series of AFP models with varying numbers of 12-residue coils (sequence TCTxSxxCxxAx) and calculated their interaction energies with ice. Using several independent computational methods, we found that the AFP-ice interaction energy increased as the number of coils increased, until an upper bound was reached. The increase of interaction energy was significant for each of the first five coils, and there was a clear synergism that gradually diminished and even decreased with further increase of the number of coils. Our results are in excellent agreement with the recently reported experimental observations. PMID:15713600

Do ice nucleating agents limit the supercooling ability of the land snail Cornu aspersum?

PubMed

Ansart, A; Nicolai, A; Vernon, P; Madec, L

2010-01-01

The supercooling ability of adults and eggs of the partially freezing tolerant land snail Cornu aspersum remains limited to high subzero temperatures (ca. -5 degree C) whatever the conditions, suggesting the presence of ice nucleating agents (INAs). In this study, we investigated the nucleation activity of the digestive tract of adult snails, eggs and their direct environment: food, faeces and soil. The mucous ribbon always present in the distal intestine of adults exhibited a heat-sensitive (i.e. organic) nucleation activity, close to that of the entire snails during dormant states (aestivation and hibernation). However, a microbial nature of these INAs could not be established in inactive snails. The food provided to active snails contained ice nucleating bacteria, which followed the digestive tract to be found in the intestine and in the faeces, but with a decreasing concentration along the transit. Eggshells also presented a heat-sensitive nucleation activity, which could be related to its structure. Moreover, eggs are laid directly in the soil which contained both organic and mineral INAs. This study is the first to demonstrate the implication of organic INAs in the cold hardiness of a terrestrial gastropod.

Intracellular Freezing in the Infective Juveniles of Steinernema feltiae: An Entomopathogenic Nematode

PubMed Central

Ali, Farman; Wharton, David A.

2014-01-01

Taking advantage of their optical transparency, we clearly observed the third stage infective juveniles (IJs) of Steinernema feltiae freezing under a cryo-stage microscope. The IJs froze when the water surrounding them froze at −2°C and below. However, they avoid inoculative freezing at −1°C, suggesting cryoprotective dehydration. Freezing was evident as a sudden darkening and cessation of IJs' movement. Freeze substitution and transmission electron microscopy confirmed that the IJs of S. feltiae freeze intracellularly. Ice crystals were found in every compartment of the body. IJs frozen at high sub-zero temperatures (−1 and −3°C) survived and had small ice crystals. Those frozen at −10°C had large ice crystals and did not survive. However, the pattern of ice formation was not well-controlled and individual nematodes frozen at −3°C had both small and large ice crystals. IJs frozen by plunging directly into liquid nitrogen had small ice crystals, but did not survive. This study thus presents the evidence that S. feltiae is only the second freeze tolerant animal, after the Antarctic nematode Panagrolaimus davidi, shown to withstand extensive intracellular freezing. PMID:24769523

76 FR 62760 - Foreign-Trade Zone 277-Western Maricopa County, AZ; Application for Temporary/Interim...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-11

...), fasteners (7318.14, 7318.15, 7318.29), hinges (8302.10), brackets (8302.50), plates (8310.00), compressors..., Sub-Zero would be able to choose the duty rate during customs entry procedures that applies to...

Mortality from desiccation contributes to a genotype–temperature interaction for cold survival in Drosophila melanogaster

PubMed Central

Kobey, Robert L.; Montooth, Kristi L.

2013-01-01

SUMMARY Survival at cold temperatures is a complex trait, primarily because of the fact that the physiological cause of injury may differ across degrees of cold exposure experienced within the lifetime of an ectothermic individual. In order to better understand how chill-sensitive insects experience and adapt to low temperatures, we investigated the physiological basis for cold survival across a range of temperature exposures from −4 to 6°C in five genetic lines of the fruit fly Drosophila melanogaster. Genetic effects on cold survival were temperature dependent and resulted in a significant genotype–temperature interaction for survival across cold temperature exposures that differ by as little as 2°C. We investigated desiccation as a potential mechanism of injury across these temperature exposures. Flies were dehydrated following exposures near 6°C, whereas flies were not dehydrated following exposures near −4°C. Furthermore, decreasing humidity during cold exposure decreased survival, and increasing humidity during cold exposure increased survival at 6°C, but not at −4°C. These results support the conclusion that in D. melanogaster there are multiple physiological mechanisms of cold-induced mortality across relatively small differences in temperature, and that desiccation contributes to mortality for exposures near 6°C but not for subzero temperatures. Because D. melanogaster has recently expanded its range from tropical to temperate latitudes, the complex physiologies underlying cold tolerance are likely to be important traits in the recent evolutionary history of this fruit fly. PMID:23197100

RSRM nozzle fixed housing cooldown test

NASA Technical Reports Server (NTRS)

Bolieau, D. J.

1989-01-01

Flight 5 aft segments with nozzles were exposed to -17 F temperatures while awaiting shipment to KSC in February, 1989. No records were found which show that any previous nozzles were exposed to air temperatures as low as those seen by the Flight 5 nozzles. Thermal analysis shows that the temperature of the fixed housing, and forward and aft exit cone components dropped as low as -10 F. Structural analysis of the nozzles at these low temperatures show the forward and aft exit cone adhesive bonds to have a positive margin of safety, based on a 2.0 safety factor. These analyses show the normal and shear stresses in the fixed housing bond as low values. However, the hoop and meridinal stresses were predicted to be in the 4000 psi range; the failure stress allowable of EA913NA adhesive at -7 F. If the bonds did break in directions perpendicular to the surfaces, called bond crazing, no normal bond strength would be lost. Testing was conducted in two phases, showing that no degradation to the adhesive bonds occurred while the Flight 5 nozzles were subjected to subzero temperatures. The results of these tests are documented. Phase 1 testing cooled a full-scale RSRM insulated fixed housing to -13 F, with extensive bondline inspections. Phase 2 testing cooled the witness panel adhesive tensile buttions to -13 F, with failure strengths recorded before, during, and after the cooldown.

Conservation of coconut (Cocos nucifera L.) germplasm at sub-zero temperature.

PubMed

Sisunandar; Sopade, Peter A; Samosir, Yohannes M S; Rival, Alain; Adkins, Steve W

2012-01-01

Protocols are proposed for the low (-20 degree C) and ultra-low (-80 degree C) temperature storage of coconut (Cocos nucifera L.) embryos. A tissue dehydration step prior to storage, and a rapid warming step upon recovery optimized the protocol. The thermal properties of water located within embryos were monitored using differential scanning calorimetry (DSC). In the most efficient version of the protocol, embryos were dehydrated under a sterile air flow in a dehydration solution containing glucose (3.33 M) and glycerol (15 percent) for 16 hours. This protocol decreased the embryo water content from 77 to 29 percent FW and at the same time reduced the amount of freezable water down to 0.03 percent. The dehydrated embryos could be stored for up to 3 weeks at -20 degree C (12 percent producing normal plants upon recovery) or 26 weeks at -80 degree C (28 percent producing normal plants upon recovery). These results indicate that it is possible to store coconut germplasm on a medium term basis using an ultra-deep freezer unit. However for more efficient, long term storage, cryopreservation remains the preferred option.

Enhanced Radiation Resistance of Methanosarcina soligelidi SMA-21, a New Methanogenic Archaeon Isolated from a Siberian Permafrost-Affected Soil in Direct Comparison to Methanosarcina barkeri.

PubMed

Morozova, Daria; Moeller, Ralf; Rettberg, Petra; Wagner, Dirk

2015-11-01

Permafrost-affected soils are characterized by a high abundance and diversity of methanogenic communities, which are considered suitable model organisms for potential life on Mars. Methanogens from Siberian permafrost have been proven to be highly resistant against divers stress conditions such as subzero temperatures, desiccation, and simulated thermophysical martian conditions. Here, we studied the radiation resistance of the currently described new species Methanosarcina soligelidi SMA-21, which was isolated from a Siberian permafrost-affected soil, in comparison to Methanosarcina barkeri, which is used as a reference organism from a nonpermafrost soil environment. Both strains were exposed to solar UV and ionizing radiation to assess their limits of survival. Methanosarcina soligelidi exhibit an increase in radiation resistance to UV (2.5- to 13.8-fold) and ionizing radiation (46.6-fold) compared to M. barkeri. The F10 (UVC) and D10 (X-rays) values of M. soligelidi are comparable to values for the well-known, highly radioresistant species Deinococcus radiodurans. In contrast, the radiation response of M. barkeri was highly sensitive to UV and ionizing radiation comparably to Escherichia coli and other radiosensitive microorganisms. This study showed that species of the same genus respond differently to UV and ionizing radiation, which might reflect the adaptation of Methanosarcina soligelidi SMA-21 to the harsh environmental conditions of the permafrost habitat. Methanogenic archaea-Environmental UV-Ionizing radiation-Permafrost-Radiation resistance-Mars.

Frequent exposure to suboptimal temperatures in vaccine cold-chain system in India: results of temperature monitoring in 10 states.

PubMed

Murhekar, Manoj V; Dutta, Srihari; Kapoor, Ambujam Nair; Bitragunta, Sailaja; Dodum, Raja; Ghosh, Pramit; Swamy, Karumanagounder Kolanda; Mukhopadhyay, Kalyanranjan; Ningombam, Somorjit; Parmar, Kamlesh; Ravishankar, Devegowda; Singh, Balraj; Singh, Varsha; Sisodiya, Rajesh; Subramanian, Ramaratnam; Takum, Tana

2013-12-01

To estimate the proportion of time the vaccines in the cold-chain system in India are exposed to temperatures of < 0 or > 8 °C. In each of 10 states, the largest district and the one most distant from the state capital were selected for study. Four boxes, each containing an electronic temperature recorder and two vials of diphtheria, pertussis and tetanus vaccine, were placed in the state or regional vaccine store for each study state. Two of these boxes were then shipped - one per facility - towards the two most peripheral health facilities where vaccine was stored in each study district. The boxes were shipped, handled and stored as if they were routine vaccine supplies. In state, regional and district vaccine stores and peripheral health facilities, respectively, the temperatures in the boxes exceeded 8 °C for 14.3%, 13.2%, 8.3% and 14.7% of their combined storage times and fell below 0 °C for 1.5%, 0.2%, 0.6% and 10.5% of these times. The boxes also spent about 18% and 7% of their combined times in transit at < 0 and > 8 °C, respectively. In shake tests conducted at the end of the study, two thirds of the vaccine vials in the boxes showed evidence of freezing. While exposure to temperatures above 8 °C occurred at every level of vaccine storage, exposure to subzero temperatures was only frequent during vaccine storage at peripheral facilities and vaccine transportation. Systematic efforts are needed to improve temperature monitoring in the cold-chain system in India.

Stabilization of tetanus toxoid formulation containing aluminium hydroxide adjuvant against freeze-thawing.

PubMed

Solanki, Vipul A; Jain, Nishant K; Roy, Ipsita

2011-07-29

Exposure to subzero temperature leads to loss of vaccine potency. This can happen due to degradation of adjuvant surface and/or inactivation of the antigen. When adsorbed on aluminium hydroxide and subjected to freeze-thawing, tetanus toxoid was desorbed from the gel matrix and the preparation was found to lose its antigenicity. Analyses showed that the gel particles were denatured after freezing. When freeze-thawing was carried out in the presence of glucose, sorbitol and arginine, the degradation of gel particles was inhibited. A higher fraction of the protein could be retained on the gel. However, the antigenicity of these preparations was quite low. In the presence of trehalose, the protein could be partially retained on aluminium hydroxide. Being a cryoprotectant, trehalose was also able to inhibit the freezing-induced denaturation of tetanus toxoid, which resulted in retention of antigenicity of the adjuvanted toxoid. Copyright © 2011 Elsevier B.V. All rights reserved.

Interior ice/mineral/water interface dynamics (Invited)

NASA Astrophysics Data System (ADS)

Rempel, A. W.

2009-12-01

The search for life begins with the search for liquid water. In our solar system, persistent water reservoirs are invariably found together with ice. On Earth, organisms have evolved to thrive at sub-zero temperatures in ice-bound habitats that have numerous analogues throughout our solar system and beyond. To assess the potential for life requires a thorough investigation of the dynamic interactions within these deposits. Well-established thermodynamic principles govern the stable coexistence of premelted liquid at the interface between ice and other minerals. Foreign constituents are efficiently rejected from the ice crystal lattice and are concentrated in residual liquid regions instead. This gains added importance with the recognition that the most fundamental requirements for survival include a food source and the removal of waste. This talk reviews the astrobiological implications of the availability, behavior, and properties of liquid water in association with the interiors of icy bodies and ice-mineral interfacial regions.

Cold hardiness in molluscs

NASA Astrophysics Data System (ADS)

Ansart, Armelle; Vernon, Philippe

2003-05-01

Molluscs inhabit all types of environments: seawater, intertidal zone, freshwater and land, and of course may have to deal with subzero temperatures. Ectotherm animals survive cold conditions by avoiding it by extensive supercooling (freezing avoidant species) or by bearing the freezing of their extracellular body fluids (freezing tolerant species). Although some studies on cold hardiness are available for intertidal molluscs, they are scarce for freshwater and terrestrial ones. Molluscs often exhibit intermediary levels of cold hardiness, with a moderate or low ability to supercool and a limited survival to the freezing of their tissues. Several factors could be involved: their dependence on water, their ability to enter dormancy, the probability of inoculative freezing in their environment, etc. Size is an important parameter in the development of cold hardiness abilities: it influences supercooling ability in land snails, which are rather freezing avoidant and survival to ice formation in intertidal organisms, which generally tolerate freezing.

The 70 kDa Heat Shock Protein Assists during the Repair of Chilling Injury in the Insect, Pyrrhocoris apterus

PubMed Central

Koštál, Vladimír; Tollarová-Borovanská, Michaela

2009-01-01

Background The Pyrrhocoris apterus (Insecta: Heteroptera) adults attain high levels of cold tolerance during their overwintering diapause. Non-diapause reproducing adults, however, lack the capacity to express a whole array of cold-tolerance adaptations and show relatively low survival when exposed to sub-zero temperatures. We assessed the competence of non-diapause males of P. apterus for responding to heat- and cold-stresses by up-regulation of 70 kDa heat shock proteins (Hsps) and the role of Hsps during repair of heat- and cold-induced injury. Principal Findings The fragments of P. apterus homologues of Hsp70 inducible (PaHsp70) and cognate forms (PaHsc70) were cloned and sequenced. The abundance of mRNA transcripts for the inducible form (qPCR) and corresponding protein (Western blotting) were significantly up-regulated in response to high and low temperature stimuli. In the cognate form, mRNA was slightly up-regulated in response to both stressors but very low or no up-regulation of protein was apparent after heat- or cold-stress, respectively. Injection of 695 bp-long Pahsp70 dsRNA (RNAi) caused drastic suppression of the heat- and cold-stress-induced Pahsp70 mRNA response and the up-regulation of corresponding protein was practically eliminated. Our RNAi predictably prevented recovery from heat shock and, in addition, negatively influenced repair of chilling injuries caused by cold stress. Cold tolerance increased when the insects were first exposed to a mild heat shock, in order to trigger the up-regulation of PaHsp70, and subsequently exposed to cold stress. Conclusion Our results suggest that accumulation of PaHsp70 belongs to a complex cold tolerance adaptation in the insect Pyrrhocoris apterus. PMID:19229329

Field Performance of Inverter-Driven Heat Pumps in Cold Climates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williamson, James; Aldrich, Robb

2015-08-19

Traditionally, air-source heat pumps (ASHPs) have been used more often in warmer climates; however, some new ASHPs are gaining ground in colder areas. These systems operate at subzero (Fahrenheit) temperatures and many do not include backup electric resistance elements. There are still uncertainties, however, about capacity and efficiency in cold weather. Also, questions such as “how cold is too cold?” do not have clear answers. These uncertainties could lead to skepticism among homeowners; poor energy savings estimates; suboptimal system selection by heating, ventilating, and air-conditioning contractors; and inconsistent energy modeling. In an effort to better understand and characterize the heatingmore » performance of these units in cold climates, the U.S. Department of Energy Building America team, Consortium for Advanced Residential Buildings (CARB), monitored seven inverter-driven, ductless ASHPs across the Northeast. Operating data were collected for three Mitsubishi FE18 units, three Mitsubishi FE12 units, and one Fujitsu 15RLS2 unit. The intent of this research was to assess heat output, electricity consumption, and coefficients of performance (COPs) at various temperatures and load conditions. This assessment was accomplished with long- and short-term tests that measured power consumption; supply, return, and outdoor air temperatures; and airflow through the indoor fan coil.« less

Warming increases methylmercury production in an Arctic soil

DOE PAGES

Yang, Ziming; Fang, Wei; Lu, Xia; ...

2016-04-29

The rapid temperature rise in Arctic permafrost concerns not only the degradation of stored soil organic carbon (SOC) and climate feedback, but also the production and bioaccumulation of methylmercury (MeHg) that may endanger humans, as well as wildlife in terrestrial, aquatic, and marine ecosystems. Decomposition of SOC provides an energy source for microbial methylation, although little is known how rapid permafrost thaw affects Hg methylation and how SOC degradation is coupled to MeHg biosynthesis. We describe rates of MeHg production in Arctic soils from an 8-month warming microcosm experiment under anoxic conditions. MeHg production increased >10 fold in both organic-more » and the mineral-rich soil layers at a warmer temperature (8 C) compared to a sub-zero temperature ( 2 C). MeHg production was positively correlated to methane and ferrous ion concentrations, suggesting that Hg methylation is coupled with methanogenesis and iron reduction. Labile SOC, such as reducing sugars and alcohol, were particularly effective in fueling the initial rapid biosynthesis of MeHg. In freshly amended Hg we found that there was more bioavailable than existing Hg in the mineral soil. Finally, the data indicate that climate warming and permafrost thaw could greatly enhance MeHg production, thereby impacting Arctic aquatic and marine ecosystems through biomagnification in the food web.« less

Environmental Stress Testing of the Single Sample Cylinder: A Proven Consensus Standard for Internal Gas Analysis (IGA) or Residual Gas Analysis (RGA)

NASA Technical Reports Server (NTRS)

Schuessler, Philipp WH

2010-01-01

In August 2008, Schuessler Consulting was contracted by NASA GSFC in support of the NASA Electronic Parts and Packaging (NEPP) program to perform two separate studies on moisture laden air in a stainless steel cylinder that had been designed to become a consensus standard for Test Method 1018. This Test Method was originally released for hybrids under Mil. Std. 883 but was quickly utilized on other microelectronic devices under the auspice of Mil. Std. 750. The cylinder had subsequently been fabricated for the 750 community. It was back-filled with moist air and subsequently analyzed over a period of time under a previous NASA contract. It had been shown that moisture in the 4000 - 5000 ppm range could be analyzed rather precisely with a mass spectrometer, commonly referred to as a Residual Gas Analyzer (RGA). The scope of this study was to ascertain if the composition and precision varied as a function of thermal shock at sub-zero temperatures and whether there was consensus when the standard was submitted to other RGA units. It was demonstrated and published that the consensus standard would yield precise RGA data for moisture within +/- 1% when optimized for a given RGA unit. It has been subsequently shown in this study at Oneida Research Services, that sub-zero storage did not affect that precision when a well-defined protocol for the analysis was followed. The consensus standard was taken to a second facility for analysis where it was found that moisture adsorption on the transfer lines caused precision to drop to +/- 12%. The Single Sample Cylinder (SSC) is a one liter stainless steel cylinder with associated sampling valves and has considerable weight and volume. But this considerable size allows for approximately 300 gas samples of the same composition to be delivered to any RGA unit. Lastly, a smaller cylinder, approximately 75 cc, of a second consensus standard was fabricated and tested with a different mix of fixed gases where moisture was kept in the 100 ppm range. This second standard has the potential of providing 30 gaseous samples and can be readily shipped to any analytical facility that desires to generate comparison RGA data. A series of comparison residual gas analyses was performed at the Honeywell Federal Manufacturing & Technologies facility in the National Nuclear Facility Administration s plant in Kansas City to complete this project. It was shown that improvements in the precision of a given RGA unit can be done by controlling the cycle time for each analysis and increasing analysis temperatures to minimize moisture adsorption. It was also found that a "one time event" in the subzero storage of the large SSC did not effect the units ability to continuously supply precise samples of the same chemistry, however the "event" caused a permanent +8% shift in the reported value of the moisture content. Lastly, a set of SSC RGA results was plotted on a common graph with DSCC "correlation study" RGA data. The result demonstrates the ability of the SSC to remove many of the individual variances that single, individual samples introduce. The consensus standards are now in storage at Oneida Research Services, one of the DSCC certified houses that does RGA to Military Standards, where they await future studies. The analytical data and the operational parameters of the instruments used are provided in the following discussion. Limitations and suggested means for improvement of both precision and accuracy are provided.

Low-temperature tolerance and cold hardening of cacti

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nobel, P.S.

Reduced uptake by the chlorenchyma cells of cacti of a stain (neutral red) was used as an indicator of low-temperature damage resulting from cooling stems in the laboratory. Necrosis set in a few degrees below the temperature at which the fraction of cells accumulating stain was reduced by 50%. Coryphantha vivipara, Opuntia polyacantha, and Pediocactus simpsonii, which range to over 300 m altitude in southern Wyoming, were quite cold tolerant. Relationships among tissue cold sensitivity, morphological features which protect the stems from low temperatures, and the occurrence of species in progressively colder regions were investigated. Differences in tissue cold sensitivitymore » accounted for the approx. = 600 m higher elevational limit of Coryphantha vivipara var. rosea compared to the morphologically similar var. deserti in southern Nevada. In contrast, morphological differences alone could adequately explain the relative northern limits of the columnar cacti Carnegiea gigantea vs Stenocereus gummosus and the barrel cacti Ferocactus acanthodes vs. F. wislizenii in the southwestern United States, as previously indicated using a computer model. Cold hardening in response to decreasing day/night air temperatures was observed for 10 species. A decrease from 50/sup 0//40/sup 0/ to 10/sup 0//0/sup 0/ lowered by 4/sup 0/ the temperature at which the fraction of the chlorenchyma cells taking up stain was reduced 50% for both D. rhodacantha and T. candicans, with a half-time for the shift of approx. = 3 d. The tolerance of subzero temperatures and the ability to cold harden allow cacti to range into regions with considerable wintertime freezing.« less

Confocal microscopy and 3-D distribution of dead cells in cryopreserved pancreatic islets

NASA Astrophysics Data System (ADS)

Merchant, Fatima A.; Aggarwal, Shanti J.; Diller, Kenneth R.; Bartels, Keith A.; Bovik, Alan C.

1992-06-01

Our laboratory is involved in studies of changes in shape and size of biological specimens under osmotic stress at ambient and sub-zero temperatures. This paper describes confocal microscopy, image processing and analysis of 3-D distribution of cells in acridine orange/propidium iodide (AO/PI) fluorescent stained frozen-thawed islet of Langerhans. Isolated and cultured rat pancreatic islets were frozen and thawed in 2 M dimethylsulfoxide and examined under a Zeiss laser scanning confocal microscope. Two micrometers to five micrometers serial sections of the islets were obtained and processed to obtain high contrast images which were later processed in two steps. The first step consisted of the isolation of the region of interest by template masking followed by grey level thresholding to obtain a binary image. Three-dimensional blob coloring algorithm was applied and the number of voxels in each region and the number of regions were counted. The volumetric distribution of the dead cells in the islets was computed by calculating the distance from the center of each blob to the centroid of the 3-D image. An increase in the number of blobs moving from the center toward the periphery of the islet was observed indicating that the freeze damage was more concentrated in the outer edges of the islet.

Perturbation of bacterial ice nucleation activity by a grass antifreeze protein.

PubMed

Tomalty, Heather E; Walker, Virginia K

2014-09-26

Certain plant-associating bacteria produce ice nucleation proteins (INPs) which allow the crystallization of water at high subzero temperatures. Many of these microbes are considered plant pathogens since the formed ice can damage tissues, allowing access to nutrients. Intriguingly, certain plants that host these bacteria synthesize antifreeze proteins (AFPs). Once freezing has occurred, plant AFPs likely function to inhibit the growth of large damaging ice crystals. However, we postulated that such AFPs might also serve as defensive mechanisms against bacterial-mediated ice nucleation. Recombinant AFP derived from the perennial ryegrass Lolium perenne (LpAFP) was combined with INP preparations originating from the grass epiphyte, Pseudomonas syringae. The presence of INPs had no effect on AFP activity, including thermal hysteresis and ice recrystallization inhibition. Strikingly, the ice nucleation point of the INP was depressed up to 1.9°C in the presence of LpAFP, but a recombinant fish AFP did not lower the INP-imposed freezing point. Assays with mutant LpAFPs and the visualization of bacterially-displayed fluorescent plant AFP suggest that INP and LpAFP can interact. Thus, we postulate that in addition to controlling ice growth, plant AFPs may also function as a defensive strategy against the damaging effects of ice-nucleating bacteria. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

Inhibiting ice recrystallization and optimization of cell viability after cryopreservation.

PubMed

Chaytor, Jennifer L; Tokarew, Jacqueline M; Wu, Luke K; Leclère, Mathieu; Tam, Roger Y; Capicciotti, Chantelle J; Guolla, Louise; von Moos, Elisabeth; Findlay, C Scott; Allan, David S; Ben, Robert N

2012-01-01

The ice recrystallization inhibition activity of various mono- and disaccharides has been correlated with their ability to cryopreserve human cell lines at various concentrations. Cell viabilities after cryopreservation were compared with control experiments where cells were cryopreserved with dimethylsulfoxide (DMSO). The most potent inhibitors of ice recrystallization were 220 mM solutions of disaccharides; however, the best cell viability was obtained when a 200 mM d-galactose solution was utilized. This solution was minimally cytotoxic at physiological temperature and effectively preserved cells during freeze-thaw. In fact, this carbohydrate was just as effective as a 5% DMSO solution. Further studies indicated that the cryoprotective benefit of d-galactose was a result of its internalization and its ability to mitigate osmotic stress, prevent intracellular ice formation and/or inhibit ice recrystallization. This study supports the hypothesis that the ability of a cryoprotectant to inhibit ice recrystallization is an important property to enhance cell viability post-freeze-thaw. This cryoprotective benefit is observed in three different human cell lines. Furthermore, we demonstrated that the ability of a potential cryoprotectant to inhibit ice recrystallation may be used as a predictor of its ability to preserve cells at subzero temperatures.

77 FR 5784 - Decision and Order Granting a Waiver to Sub-Zero From the Department of Energy Residential...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-06

... electric refrigerator and refrigerator-freezer test procedures for determining the energy consumption of... compressors using an alternate test procedure that takes this technology into account when measuring energy.... Bryan Berringer, U.S. Department of Energy, Building Technologies Program, Mailstop EE-2J, 1000...

A low membrane lipid phase transition temperature is associated with a high cryotolerance of Lactobacillus delbrueckii subspecies bulgaricus CFL1.

PubMed

Gautier, J; Passot, S; Pénicaud, C; Guillemin, H; Cenard, S; Lieben, P; Fonseca, F

2013-09-01

The mechanisms of cellular damage that lactic acid bacteria incur during freeze-thaw processes have not been elucidated to date. Fourier transform infrared spectroscopy was used to investigate in situ the lipid phase transition behavior of the membrane of Lactobacillus delbrueckii ssp. bulgaricus CFL1 cells during the freeze-thaw process. Our objective was to relate the lipid membrane behavior to membrane integrity losses during freezing and to cell-freezing resistance. Cells were produced by using 2 different culture media: de Man, Rogosa, and Sharpe (MRS) broth (complex medium) or mild whey-based medium (minimal medium commonly used in the dairy industry), to obtain different membrane lipid compositions corresponding to different recovery rates of cell viability and functionality after freezing. The lipid membrane behavior studied by Fourier transform infrared spectroscopy was found to be different according to the cell lipid composition and cryotolerance. Freeze-resistant cells, exhibiting a higher content of unsaturated and cyclic fatty acids, presented a lower lipid phase transition temperature (Ts) during freezing (Ts=-8°C), occurring within the same temperature range as the ice nucleation, than freeze-sensitive cells (Ts=+22°C). A subzero value of lipid phase transition allowed the maintenance of the cell membrane in a relatively fluid state during freezing, thus facilitating water flux from the cell and the concomitant volume reduction following ice formation in the extracellular medium. In addition, the lipid phase transition of freeze-resistant cells occurred within a short temperature range, which could be ascribed to a reduced number of fatty acids, representing more than 80% of the total. This short lipid phase transition could be associated with a limited phenomenon of lateral phase separation and membrane permeabilization. This work highlights that membrane phase transitions occurring during freeze-thawing play a fundamental role in the cryotolerance of Lb. delbrueckii ssp. bulgaricus CFL1 cells. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Positive selection in octopus haemocyanin indicates functional links to temperature adaptation.

PubMed

Oellermann, Michael; Strugnell, Jan M; Lieb, Bernhard; Mark, Felix C

2015-07-05

Octopods have successfully colonised the world's oceans from the tropics to the poles. Yet, successful persistence in these habitats has required adaptations of their advanced physiological apparatus to compensate impaired oxygen supply. Their oxygen transporter haemocyanin plays a major role in cold tolerance and accordingly has undergone functional modifications to sustain oxygen release at sub-zero temperatures. However, it remains unknown how molecular properties evolved to explain the observed functional adaptations. We thus aimed to assess whether natural selection affected molecular and structural properties of haemocyanin that explains temperature adaptation in octopods. Analysis of 239 partial sequences of the haemocyanin functional units (FU) f and g of 28 octopod species of polar, temperate, subtropical and tropical origin revealed natural selection was acting primarily on charge properties of surface residues. Polar octopods contained haemocyanins with higher net surface charge due to decreased glutamic acid content and higher numbers of basic amino acids. Within the analysed partial sequences, positive selection was present at site 2545, positioned between the active copper binding centre and the FU g surface. At this site, methionine was the dominant amino acid in polar octopods and leucine was dominant in tropical octopods. Sites directly involved in oxygen binding or quaternary interactions were highly conserved within the analysed sequence. This study has provided the first insight into molecular and structural mechanisms that have enabled octopods to sustain oxygen supply from polar to tropical conditions. Our findings imply modulation of oxygen binding via charge-charge interaction at the protein surface, which stabilize quaternary interactions among functional units to reduce detrimental effects of high pH on venous oxygen release. Of the observed partial haemocyanin sequence, residue 2545 formed a close link between the FU g surface and the active centre, suggesting a role as allosteric binding site. The prevalence of methionine at this site in polar octopods, implies regulation of oxygen affinity via increased sensitivity to allosteric metal binding. High sequence conservation of sites directly involved in oxygen binding indicates that functional modifications of octopod haemocyanin rather occur via more subtle mechanisms, as observed in this study.

Life at extreme elevations on Atacama volcanoes: the closest thing to Mars on Earth?

PubMed

Schmidt, S K; Gendron, E M S; Vincent, K; Solon, A J; Sommers, P; Schubert, Z R; Vimercati, L; Porazinska, D L; Darcy, J L; Sowell, P

2018-03-20

Here we describe recent breakthroughs in our understanding of microbial life in dry volcanic tephra ("soil") that covers much of the surface area of the highest elevation volcanoes on Earth. Dry tephra above 6000 m.a.s.l. is perhaps the best Earth analog for the surface of Mars because these "soils" are acidic, extremely oligotrophic, exposed to a thin atmosphere, high UV fluxes, and extreme temperature fluctuations across the freezing point. The simple microbial communities found in these extreme sites have among the lowest alpha diversity of any known earthly ecosystem and contain bacteria and eukaryotes that are uniquely adapted to these extreme conditions. The most abundant eukaryotic organism across the highest elevation sites is a Naganishia species that is metabolically versatile, can withstand high levels of UV radiation and can grow at sub-zero temperatures, and during extreme diurnal freeze-thaw cycles (e.g. - 10 to + 30 °C). The most abundant bacterial phylotype at the highest dry sites sampled (6330 m.a.s.l. on Volcán Llullaillaco) belongs to the enigmatic B12-WMSP1 clade which is related to the Ktedonobacter/Thermosporothrix clade that includes versatile organisms with the largest known bacterial genomes. Close relatives of B12-WMSP1 are also found in fumarolic soils on Volcán Socompa and in oligotrophic, fumarolic caves on Mt. Erebus in Antarctica. In contrast to the extremely low diversity of dry tephra, fumaroles found at over 6000 m.a.s.l. on Volcán Socompa support very diverse microbial communities with alpha diversity levels rivalling those of low elevation temperate soils. Overall, the high-elevation biome of the Atacama region provides perhaps the best "natural experiment" in which to study microbial life in both its most extreme setting (dry tephra) and in one of its least extreme settings (fumarolic soils).

Numerical investigation of the coagulation mixing between dust and hygroscopic aerosol particles and its impacts

NASA Astrophysics Data System (ADS)

Tsai, I.-Chun; Chen, Jen-Ping; Lin, Yi-Chiu; Chung-Kuang Chou, Charles; Chen, Wei-Nai

2015-05-01

A statistical-numerical aerosol parameterization was incorporated into the Community Multiscale Air Quality modeling system to study the coagulation mixing process focusing on a dust storm event that occurred over East Asia. Simulation results show that the coagulation mixing process tends to decrease aerosol mass, surface area, and number concentrations over the dust source areas. Over the downwind oceanic areas, aerosol concentrations generally increased due to enhanced sedimentation as particles became larger upon coagulation. The mixture process can reduce the overall single-scattering albedo by up to 10% as a result of enhanced core with shell absorption by dust and reduction in the number of scattering particles. The enhanced dry deposition speed also altered the vertical distribution. In addition, the ability of aerosol particles to serve as cloud condensation nuclei (CCN) increased from around 107 m-3 to above 109 m-3 over downwind areas because a large amount of mineral dust particles became effective CCN with solute coating, except over the highly polluted areas where multiple collections of hygroscopic particles by dust in effect reduced CCN number. This CCN effect is much stronger for coagulation mixing than by the uptake of sulfuric acid gas on dust, although the nitric acid gas uptake was not investigated. The ability of dust particles to serve as ice nuclei may decrease or increase at low or high subzero temperatures, respectively, due to the switching from deposition nucleation to immersion freezing or haze freezing.

Microbial cell retention in a melting High Arctic snowpack, Svalbard

NASA Astrophysics Data System (ADS)

Zarsky, Jakub; Björkman, Mats; Kühnel, Rafael; Hell, Katherina; Hodson, Andy; Sattler, Birgit; Psenner, Roland

2014-05-01

Introduction The melting snow pack represents a highly dynamic system not only for chemical compounds but also for bacterial cells. Microbial activity was found at subzero temperatures in ice veins when liquid water persists due to high concentration of ions on the surface of snow crystals and brine channels between large ice crystals in ice. Several observations also suggest microbial activity under subzero temperatures in seasonal snow. Even with regard to the spatial and temporal relevance of snow ecosystems, microbial activity in such an extreme habitat represents a relatively small proportion in the carbon flux of the global ecosystem and even of the glacial ecosystems specifically. On the other hand, it represents a remarkable piece of mosaic of the microbial activity in glacial ecosystems because the snow pack represents the first contact between the atmosphere and cryosphere. This topic also embodies vital crossovers to biogeochemistry and ecotoxicology, offering a quantitative view of utilization of various substrates relevant for downstream ecosystems. Here we present our study of the dynamics of both solvents and cells suspended in meltwater of the melting snowpack on a high arctic glacier to demonstrate the spatio-temporal constraint of interaction between solvent and bacterial cells in this environment. Method We used 6 lysimeters inserted into the bottom of the snowpack to collect replicated samples of melt water before it comes into contact with basal ice or slush layer at the base of the snow pack. The sampling site was chosen at Midre Lovénbreen (Svalbard, Kongsfjorden, MLB stake 6) where the snow pack showed melting on the surface but the basal ice was still dry. Sampling was conducted in June 2010 for a period of 10 days once per day and the snow profile was sampled according to distinguished layers in the profile at the beginning of the field mission and as bulk at its end. The height of snow above the lysimeters dropped from the initial 74 cm to the final 38 cm. The major ion composition (IC), pH, conductivity and cell abundances were measured. Results and conlusions The removal of microbial cells from a high arctic snowpack resembles an elution sequence similar to that of hydrophobic compounds a process that helps glaciers retain a microbial biomass upon their surface, even after the demise of the snow cover. The snowpack and the glacier surface therefore act as an accumulator of cells during the melt season. This suggests that wet snowpacks, even on the surface of high arctic glaciers, are likely to be dynamic ecosystems in their own right. In our study, a clear ion elution sequence was observed that resembled earlier reports and caused high concentrations of ions in snowpack runoff at the start of the snow melt, which rapidly decreased as snow melt proceeded. Chloride, sulfate, nitrate, sodium and potassium experienced a 50 % elution before 20 - 25 % of the snowpack water content was lost. By contrast, cell removal only reached the 50 % level after ~70 % snowpack depletion. In contrast to our expectations, the calculated cell budget between the initial and final snowpack (including the cell loss by elution), revealed a significant increase of the total cell numbers, i.e. more than twice the original number. Assuming aeolian deposition processes to be low, this suggests cell proliferation as a contribution to the observed "retention effect". Precipitation was the major cell contributor to the snowpack upon Midtre Lovénbreen. An overall low cell concentration was therefore found within the snowpack stratigraphy, where snow layers frequently showed cell abundances similar to those of cloud water. This was in contrast to the nearby and more wind exposed sites examined in the Kongsfjorden area in 2007. However, layers of higher dust deposition were concomitant with one order of magnitude higher cell abundances, indicating that wind dispersal from locally exposed rocks supplements the atmospheric cell input.

Tolerance of subzero winter cold in kudzu (Pueraria montana var. lobata) and its implications for northward migration in a warming climate

USDA-ARS?s Scientific Manuscript database

Kudzu (Pueraria montana var. lobata) is an important invasive species that was planted throughout southeastern North America until the mid-20th century. Winter survival is commonly assumed to control its distribution; however, its cold tolerance thresholds have not been determined. Here, we used bio...

Ice-Binding Proteins in Plants

PubMed Central

Bredow, Melissa; Walker, Virginia K.

2017-01-01

Sub-zero temperatures put plants at risk of damage associated with the formation of ice crystals in the apoplast. Some freeze-tolerant plants mitigate this risk by expressing ice-binding proteins (IBPs), that adsorb to ice crystals and modify their growth. IBPs are found across several biological kingdoms, with their ice-binding activity and function uniquely suited to the lifestyle they have evolved to protect, be it in fishes, insects or plants. While IBPs from freeze-avoidant species significantly depress the freezing point, plant IBPs typically have a reduced ability to lower the freezing temperature. Nevertheless, they have a superior ability to inhibit the recrystallization of formed ice. This latter activity prevents ice crystals from growing larger at temperatures close to melting. Attempts to engineer frost-hardy plants by the controlled transfer of IBPs from freeze-avoiding fish and insects have been largely unsuccessful. In contrast, the expression of recombinant IBP sequences from freeze-tolerant plants significantly reduced electrolyte leakage and enhanced freezing survival in freeze-sensitive plants. These promising results have spurred additional investigations into plant IBP localization and post-translational modifications, as well as a re-evaluation of IBPs as part of the anti-stress and anti-pathogen axis of freeze-tolerant plants. Here we present an overview of plant freezing stress and adaptation mechanisms and discuss the potential utility of IBPs for the generation of freeze-tolerant crops. PMID:29312400

Ice-Binding Proteins in Plants.

PubMed

Bredow, Melissa; Walker, Virginia K

2017-01-01

Sub-zero temperatures put plants at risk of damage associated with the formation of ice crystals in the apoplast. Some freeze-tolerant plants mitigate this risk by expressing ice-binding proteins (IBPs), that adsorb to ice crystals and modify their growth. IBPs are found across several biological kingdoms, with their ice-binding activity and function uniquely suited to the lifestyle they have evolved to protect, be it in fishes, insects or plants. While IBPs from freeze-avoidant species significantly depress the freezing point, plant IBPs typically have a reduced ability to lower the freezing temperature. Nevertheless, they have a superior ability to inhibit the recrystallization of formed ice. This latter activity prevents ice crystals from growing larger at temperatures close to melting. Attempts to engineer frost-hardy plants by the controlled transfer of IBPs from freeze-avoiding fish and insects have been largely unsuccessful. In contrast, the expression of recombinant IBP sequences from freeze-tolerant plants significantly reduced electrolyte leakage and enhanced freezing survival in freeze-sensitive plants. These promising results have spurred additional investigations into plant IBP localization and post-translational modifications, as well as a re-evaluation of IBPs as part of the anti-stress and anti-pathogen axis of freeze-tolerant plants. Here we present an overview of plant freezing stress and adaptation mechanisms and discuss the potential utility of IBPs for the generation of freeze-tolerant crops.

3D-macroporous chitosan-based scaffolds with in situ formed Pd and Pt nanoparticles for nitrophenol reduction.

PubMed

Berillo, Dmitriy; Cundy, Andrew

2018-07-15

3D-macroporous chitosan-based scaffolds (cryogels) were produced via growth of metal-polymer coordinated complexes and electrostatic interactions between oppositely charged groups of chitosan and metal ions under subzero temperatures. A mechanism of reduction of noble metal complexes inside the cryogel walls by glutaraldehyde is proposed, which produces discrete and dispersed noble metal nanoparticles. 3D-macroporous scaffolds prepared under different conditions were characterised using TGA, FTIR, nitrogen adsorption, SEM, EDX and TEM, and the distribution of platinum nanoparticles (PtNPs) and palladium nanoparticles (PdNPs) in the material assessed. The catalytic activity of the in situ synthesised PdNPs, at 2.6, 12.5 and 21.0 μg total mass, respectively, was studied utilising a model system of 4-nitrophenol reduction. The kinetics of the reaction under different conditions (temperature, concentration of catalyst) were examined, and a decrease of catalytic activity was not observed over 17 treatment cycles. Increasing the temperature of the catalytic reaction from 10 to 22 and 35 °C by PdNPs supported within the cryogel increased the kinetic rate by 44 and 126%, respectively. Turnover number and turnover frequency of the PdNPs catalysts at room temperature were in the range 0.20-0.53 h -1 . The conversion degree of 4-nitrophenol at room temperature reached 98.9% (21.0 μg PdNPs). Significantly less mass of palladium nanoparticles (by 30-40 times) was needed compared to published data to obtain comparable rates of reduction of 4-nitrophenol. Copyright © 2018 Elsevier Ltd. All rights reserved.

Cryoprotective ability of betaine-type metabolite analogs during freezing denaturation of enzymes.

PubMed

Nakagawa, Yuichi; Sota, Masahiro; Koumoto, Kazuya

2015-08-01

To evaluate an analog library of betaine-type cellular metabolites, which are naturally found in polar fish for survival in subzero temperatures, for preventing denaturation of enzymes during freezing. Comparison of the cryoprotective ability of reported cryoprotectants, such as dimethylsulfoxide, glycerol, ectoine, hydroxyectoine, and trehalose, with betaine-type analogs using α-glucosidase revealed that analogs introducing C3-C6 alkyl chains into an ammonium cation retained 20 % higher activity than the control cryoprotectants at the same concentration. In particular, the analog possessing triplicate n-butyl chains showed a profound effect. It allowed retention of enzyme activity to 95 % even after 100 freeze-thaw cycles, while addition of the control cryoprotectants decreased the activity to 10-20 %. The cryoprotective ability of betaine-type analogs can be applied not only to α-glucosidase but also other enzymes such as β-glucosidase, alkaline phosphatase, lactose dehydrogenase, sulfatase, and horseradish peroxidase. Synthetic betaine-type metabolite analogs possess practicable cryoprotective ability for various enzymes, and are considerably superior to previously reported cryoprotectants.

Temperature control during therapeutic hypothermia for newborn encephalopathy using different Blanketrol devices.

PubMed

Laptook, Abbot R; Kilbride, Howard; Shepherd, Edward; McDonald, Scott A; Shankaran, Seetha; Truog, William; Das, Abhik; Higgins, Rosemary D

2014-12-01

Therapeutic hypothermia improves the survival and neurodevelopmental outcome of infants with newborn encephalopathy of a hypoxic-ischemic origin. The NICHD Neonatal Research Network (NRN) Whole Body Cooling trial used the Cincinnati Sub-Zero Blanketrol II to achieve therapeutic hypothermia. The Blanketrol III is now available and provides additional cooling modes that may result in better temperature control. This report is a retrospective comparison of infants undergoing hypothermia using two different cooling modes of the Blanketrol device. Infants from the NRN trial were cooled with the Blanketrol II using the Automatic control mode (B2 cohort) and were compared with infants from two new NRN centers that adopted the NRN protocol and used the Blanketrol III in a gradient mode (B3 cohort). The primary outcome was the percent time the esophageal temperature stayed between 33°C and 34°C (target 33.5°C) during maintenance of hypothermia. Cohorts had similar birth weight, gestational age, and level of encephalopathy at the initiation of therapy. Baseline esophageal temperature differed between groups (36.6°C ± 1.0°C for B2 vs. 33.9°C ± 1.2°C for B3, p<0.0001) reflecting the practice of passive cooling during transport prior to initiation of active device cooling in the B3 cohort. This difference prevented comparison of temperatures during induction of hypothermia. During maintenance of hypothermia the mean and standard deviation of the percent time between 33°C and 34°C was similar for B2 compared to B3 cohorts (94.8% ± 0.1% vs. 95.8% ± 0.1%, respectively). Both the automatic and gradient control modes of the Blanketrol devices appear comparable in maintaining esophageal temperature within the target range during maintenance of therapeutic hypothermia.

Temperature Control During Therapeutic Hypothermia for Newborn Encephalopathy Using Different Blanketrol Devices

PubMed Central

Kilbride, Howard; Shepherd, Edward; McDonald, Scott A.; Shankaran, Seetha; Truog, William; Das, Abhik; Higgins, Rosemary D.

2014-01-01

Therapeutic hypothermia improves the survival and neurodevelopmental outcome of infants with newborn encephalopathy of a hypoxic-ischemic origin. The NICHD Neonatal Research Network (NRN) Whole Body Cooling trial used the Cincinnati Sub-Zero Blanketrol II to achieve therapeutic hypothermia. The Blanketrol III is now available and provides additional cooling modes that may result in better temperature control. This report is a retrospective comparison of infants undergoing hypothermia using two different cooling modes of the Blanketrol device. Infants from the NRN trial were cooled with the Blanketrol II using the Automatic control mode (B2 cohort) and were compared with infants from two new NRN centers that adopted the NRN protocol and used the Blanketrol III in a gradient mode (B3 cohort). The primary outcome was the percent time the esophageal temperature stayed between 33°C and 34°C (target 33.5°C) during maintenance of hypothermia. Cohorts had similar birth weight, gestational age, and level of encephalopathy at the initiation of therapy. Baseline esophageal temperature differed between groups (36.6°C±1.0°C for B2 vs. 33.9°C±1.2°C for B3, p<0.0001) reflecting the practice of passive cooling during transport prior to initiation of active device cooling in the B3 cohort. This difference prevented comparison of temperatures during induction of hypothermia. During maintenance of hypothermia the mean and standard deviation of the percent time between 33°C and 34°C was similar for B2 compared to B3 cohorts (94.8%±0.1% vs. 95.8%±0.1%, respectively). Both the automatic and gradient control modes of the Blanketrol devices appear comparable in maintaining esophageal temperature within the target range during maintenance of therapeutic hypothermia. PMID:25285767

Effects of warming rate, temperature, and antifreeze proteins on the survival of mouse spermatozoa frozen at an optimal rate.

PubMed

Koshimoto, Chihiro; Mazur, Peter

2002-08-01

We have recently reported that the survival of mouse spermatozoa is decreased when they are warmed at a suboptimal rate after being frozen at an optimal rate. We proposed that this drop in survival is caused by physical damage derived from the recrystallization of extracellular ice during slow warming. The first purpose of the present study was to determine the temperatures over which the decline in survival occurs during slow warming and the kinetics of the decline at fixed subzero temperatures. The second purpose was to examine the effects of antifreeze proteins (AFP) on the survival of slowly warmed mouse spermatozoa, the rationale being that AFP have the property of inhibiting ice recrystallization. With respect to the first point, a substantial loss in motility occurred when slow warming was continued to higher than -50 degrees C and the survival of the sperm decreased with an increase in the temperature at which slow warming was terminated. In contrast, the motility of sperm that were warmed rapidly to these temperatures remained high initially but dropped with increased holding time. At -30 degrees C, most of the drop occurred in 5 min. These results are consistent with the hypothesis that damage develops as a consequence of the recrystallization of the external ice. AFP ought to inhibit such recrystallization, but we found that the addition of AFP-I, AFP-III, and an antifreeze glycoprotein at concentrations of 1-100 microg/ml did not protect the frozen-thawed cells; rather it led to a decrease in survival that was proportional to the concentration. There was no decrease in survival from exposure to the AFP in the absence of freezing. AFP are known to produce changes in the structure and habit of ice crystals, and some have reported deleterious consequences associated with those structural changes. We suggest that such changes may be the basis of the adverse effects of AFP on the survival of the sperm, especially since mouse sperm are exquisitely sensitive to a variety of mechanical stresses.

Identification of irradiated mushrooms (in French)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bugyaki, L.

1973-01-01

From international colloquium: the identification of irradiated foodstuffs; Karlsruhe, Germany (24 Oct 1973). Cuttings from non-irradiated mushrooms, when kept at normal or sub-zero temperatares, produce new hyphae in solld culture media even after slx days, thus proving that they are living. On the other hand, cultures from mushrooms irradiated with 250 krad never show any sign of cellular proliferation. (auth)

Gypsum and hydrohalite dynamics in sea ice brines

NASA Astrophysics Data System (ADS)

Butler, Benjamin M.; Papadimitriou, Stathys; Day, Sarah J.; Kennedy, Hilary

2017-09-01

Mineral authigenesis from their dissolved sea salt matrix is an emergent feature of sea ice brines, fuelled by dramatic equilibrium solubility changes in the large sub-zero temperature range of this cryospheric system on the surface of high latitude oceans. The multi-electrolyte composition of seawater results in the potential for several minerals to precipitate in sea ice, each affecting the in-situ geochemical properties of the sea ice brine system, the habitat of sympagic biota. The solubility of two of these minerals, gypsum (CaSO4 ·2H2O) and hydrohalite (NaCl · 2H2O), was investigated in high ionic strength multi-electrolyte solutions at below-zero temperatures to examine their dissolution-precipitation dynamics in the sea ice brine system. The gypsum dynamics in sea ice were found to be highly dependent on the solubilities of mirabilite and hydrohalite between 0.2 and - 25.0 ° C. The hydrohalite solubility between - 14.3 and - 25.0 ° C exhibits a sharp change between undersaturated and supersaturated conditions, and, thus, distinct temperature fields of precipitation and dissolution in sea ice, with saturation occurring at - 22.9 ° C. The sharp changes in hydrohalite solubility at temperatures ⩽-22.9 °C result from the formation of an ice-hydrohalite aggregate, which alters the structural properties of brine inclusions in cold sea ice. Favourable conditions for gypsum precipitation in sea ice were determined to occur in the region of hydrohalite precipitation below - 22.9 ° C and in conditions of metastable mirabilite supersaturation above - 22.9 ° C (investigated at - 7.1 and - 8.2 ° C here) but gypsum is unlikely to persist once mirabilite forms at these warmer (>-22.9 °C) temperatures. The dynamics of hydrohalite in sea ice brines based on its experimental solubility were consistent with that derived from thermodynamic modelling (FREZCHEM code) but the gypsum dynamics derived from the code were inconsistent with that indicated by its experimental solubility in this system. Incorporation of hydrohalite solubility into a 1D thermodynamic model of the growth of first-year Arctic sea ice showed its precipitation to initiate once the incoming shortwave radiation dropped to 0 W m-2, and that it can reach concentrations of 9.9 g kg-1 within the upper and coldest layers of the ice pack. This suggests a limited effect of hydrohalite on the albedo of sea ice. The insights provided by the solubility measurements into the behaviour of gypsum and hydrohalite in the ice-brine system cannot be gleaned from field investigations at present.

Microbial genesis, life and death in glacial ice.

PubMed

Price, P Buford

2009-01-01

Arguments are given that terrestrial RNA and DNA may have originated in a frozen environment more than 4 billion years ago. Scenarios are developed for atmospheric transport of microbes onto glacial ice, their adaptation to subzero temperatures in the ice, and their incorporation into one of three habitats - liquid veins, mineral grain surfaces, or isolated inside 1 of the crystals that make up polycrystalline ice. The Arrhenius dependence of microbial metabolic rate on temperature is shown to match that required to repair damage owing to spontaneous DNA depurination and amino acid racemization. Even for the oldest glacial ice, microbial lifetime is shown not to be shortened by radiation damage from 238U, 232Th, or 40K in mineral dust in ice, by phage-induced lysis, or by penetrating cosmic radiation. Instead, death of those cells adapted to the hostile conditions in glacial ice is probably due to exhaustion of available nutrients. By contrast, in permafrost microbial death is more likely due to alpha-particle radiation damage from U and Th in the soil and rocks intermixed with ice. For residence times in ice longer than a million years, spore formers may be unable to compete in longevity with vegetative cells that are able to repair DNA damage via survival metabolism.

Antifreeze Peptides and Glycopeptides, and Their Derivatives: Potential Uses in Biotechnology

PubMed Central

Bang, Jeong Kyu; Lee, Jun Hyuck; Murugan, Ravichandran N.; Lee, Sung Gu; Do, Hackwon; Koh, Hye Yeon; Shim, Hye-Eun; Kim, Hyun-Cheol; Kim, Hak Jun

2013-01-01

Antifreeze proteins (AFPs) and glycoproteins (AFGPs), collectively called AF(G)Ps, constitute a diverse class of proteins found in various Arctic and Antarctic fish, as well as in amphibians, plants, and insects. These compounds possess the ability to inhibit the formation of ice and are therefore essential to the survival of many marine teleost fishes that routinely encounter sub-zero temperatures. Owing to this property, AF(G)Ps have potential applications in many areas such as storage of cells or tissues at low temperature, ice slurries for refrigeration systems, and food storage. In contrast to AFGPs, which are composed of repeated tripeptide units (Ala-Ala-Thr)n with minor sequence variations, AFPs possess very different primary, secondary, and tertiary structures. The isolation and purification of AFGPs is laborious, costly, and often results in mixtures, making characterization difficult. Recent structural investigations into the mechanism by which linear and cyclic AFGPs inhibit ice crystallization have led to significant progress toward the synthesis and assessment of several synthetic mimics of AFGPs. This review article will summarize synthetic AFGP mimics as well as current challenges in designing compounds capable of mimicking AFGPs. It will also cover our recent efforts in exploring whether peptoid mimics can serve as structural and functional mimics of native AFGPs. PMID:23752356

Ciliates from ancient permafrost: Assessment of cold resistance of the resting cysts.

PubMed

Shatilovich, Anastasia; Stoupin, Daniel; Rivkina, Elizaveta

2015-06-01

There is evidence that resting cysts of soil ciliates and numerous taxa of other protists can survive in permafrost for thousands of years at subzero temperatures; however, our knowledge about mechanisms of long term cryobiosis remains incomplete. In order to better understand the means by which ancient cysts survive, we investigated resistance to cyclical supercooling stress of resting cysts of the soil ciliate Colpoda steinii (Colpodida, Ciliophora). Three clonal strains were used for comparison, isolated from Siberian tundra soil, ancient Holocene (5-7,000 y) and late Pleistocene (32-35,000 y) permafrost sediments. To determine the viability of the ancient and contemporary ciliate cysts we improved and validated a cultivation-independent method of vital fluorescent staining with a combination of two nucleic acid binding dyes, acridine orange and propidium iodide. The viability of Colpoda steinii cysts during low-temperature experiments was measured using both the proposed vital fluorescent staining method and standard germination test. Our results indicate that the dual-fluorescence technique is a more accurate, rapid, and efficient method for estimating cyst viability. We found that cysts of ancient ciliates display lower tolerance to the impact of cyclical cold compared to cysts of contemporary ciliates from Siberian permafrost affected soils. Copyright © 2015 Elsevier GmbH. All rights reserved.

Light requirements of Australian tropical vs. cool-temperate rainforest tree species show different relationships with seedling growth and functional traits.

PubMed

Lusk, Christopher H; Kelly, Jeff W G; Gleason, Sean M

2013-03-01

A trade-off between shade tolerance and growth in high light is thought to underlie the temporal dynamics of humid forests. On the other hand, it has been suggested that tree species sorting on temperature gradients involves a trade-off between growth rate and cold resistance. Little is known about how these two major trade-offs interact. Seedlings of Australian tropical and cool-temperate rainforest trees were grown in glasshouse environments to compare growth versus shade-tolerance trade-offs in these two assemblages. Biomass distribution, photosynthetic capacity and vessel diameters were measured in order to examine the functional correlates of species differences in light requirements and growth rate. Species light requirements were assessed by field estimation of the light compensation point for stem growth. Light-demanding and shade-tolerant tropical species differed markedly in relative growth rates (RGR), but this trend was less evident among temperate species. This pattern was paralleled by biomass distribution data: specific leaf area (SLA) and leaf area ratio (LAR) of tropical species were significantly positively correlated with compensation points, but not those of cool-temperate species. The relatively slow growth and small SLA and LAR of Tasmanian light-demanders were associated with narrow vessels and low potential sapwood conductivity. The conservative xylem traits, small LAR and modest RGR of Tasmanian light-demanders are consistent with selection for resistance to freeze-thaw embolism, at the expense of growth rate. Whereas competition for light favours rapid growth in light-demanding trees native to environments with warm, frost-free growing seasons, frost resistance may be an equally important determinant of the fitness of light-demanders in cool-temperate rainforest, as seedlings establishing in large openings are exposed to sub-zero temperatures that can occur throughout most of the year.

Seasonal acclimatization of the cardiac potassium currents (IK1 and IKr) in an arctic marine teleost, the navaga cod (Eleginus navaga).

PubMed

Abramochkin, Denis V; Vornanen, Matti

2015-12-01

Several freshwater fishes of north-temperate latitudes exhibit marked seasonal changes in cardiac action potential (AP) waveform as an outcome of temperature-dependent changes in the density of delayed rectifiers (IKr, IKs) and inward rectifier (IK1) potassium currents. Thus far, ionic mechanisms of cardiac excitability in arctic marine fishes have not been examined. To this end we examined ventricular AP and the role of two major potassium currents (IK1, IKr) in repolarization of cardiac AP in winter-acclimatized (WA, caught in March) and summer-acclimatized (SA, caught in September) navaga cod (Eleginus navaga) of the White Sea. The duration of ventricular AP of WA navaga at 3 °C (APD50 = 659.5 ± 32.8 ms) was similar to the AP duration of SA navaga at 12 °C (APD50 = 543.9 ± 14.6 ms) (p > 0.05) indicating complete thermal compensation of AP duration. This acclimation effect was associated with strong up-regulation of the cardiac potassium currents in winter. Densities of ventricular IK1 (at -120 mV) and IKr (at +50 mV) of the WA navaga at 3 °C were 2.9 times and 2.8 times, respectively, higher than those of the SA navaga at 12 °C, thus indicating marked thermal overcompensation. Qualitatively similar results were obtained from atrial myocytes. Seasonal changes in IK1 and IKr are more than sufficient to explain the complete thermal compensation of ventricular AP duration. The excellent acclimation capacity of cardiac excitability of the navaga cod is probably needed to maintain high cardiac performance at subzero temperatures in winter and to increase thermal resilience of cardiac function under seasonally variable arctic temperature conditions.

Enhanced rates of enzymatic saccharification and catalytic synthesis of biofuel substrates in gelatinized cellulose generated by trifluoroacetic acid

DOE PAGES

Shiga, Tânia M.; Xiao, Weihua; Yang, Haibing; ...

2017-12-27

The crystallinity of cellulose is a principal factor limiting the efficient hydrolysis of biomass to fermentable sugars or direct catalytic conversion to biofuel components. We evaluated the impact of TFA-induced gelatinization of crystalline cellulose on enhancement of enzymatic digestion and catalytic conversion to biofuel substrates. Low-temperature swelling of cotton linter cellulose in TFA at subzero temperatures followed by gentle heating to 55 degrees C dissolves the microfibril structure and forms composites of crystalline and amorphous gels upon addition of ethanol. The extent of gelatinization of crystalline cellulose was determined by reduction of birefringence in darkfield microscopy, loss of X-ray diffractability,more » and loss of resistance to acid hydrolysis. Upon freeze-drying, an additional degree of crystallinity returned as mostly cellulose II. Both enzymatic digestion with a commercial cellulase cocktail and maleic acid/AlCl3-catalyzed conversion to 5-hydroxymethylfurfural and levulinic acid were markedly enhanced with the low-temperature swollen cellulose. Only small improvements in rates and extent of hydrolysis and catalytic conversion were achieved upon heating to fully dissolve cellulose. Low-temperature swelling of cellulose in TFA substantially reduces recalcitrance of crystalline cellulose to both enzymatic digestion and catalytic conversion. In a closed system to prevent loss of fluorohydrocarbons, the relative ease of recovery and regeneration of TFA by distillation makes it a potentially useful agent in large-scale deconstruction of biomass, not only for enzymatic depolymerization but also for enhancing rates of catalytic conversion to biofuel components and useful bio-products.« less

Enhanced rates of enzymatic saccharification and catalytic synthesis of biofuel substrates in gelatinized cellulose generated by trifluoroacetic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiga, Tânia M.; Xiao, Weihua; Yang, Haibing

The crystallinity of cellulose is a principal factor limiting the efficient hydrolysis of biomass to fermentable sugars or direct catalytic conversion to biofuel components. We evaluated the impact of TFA-induced gelatinization of crystalline cellulose on enhancement of enzymatic digestion and catalytic conversion to biofuel substrates. Low-temperature swelling of cotton linter cellulose in TFA at subzero temperatures followed by gentle heating to 55 degrees C dissolves the microfibril structure and forms composites of crystalline and amorphous gels upon addition of ethanol. The extent of gelatinization of crystalline cellulose was determined by reduction of birefringence in darkfield microscopy, loss of X-ray diffractability,more » and loss of resistance to acid hydrolysis. Upon freeze-drying, an additional degree of crystallinity returned as mostly cellulose II. Both enzymatic digestion with a commercial cellulase cocktail and maleic acid/AlCl3-catalyzed conversion to 5-hydroxymethylfurfural and levulinic acid were markedly enhanced with the low-temperature swollen cellulose. Only small improvements in rates and extent of hydrolysis and catalytic conversion were achieved upon heating to fully dissolve cellulose. Low-temperature swelling of cellulose in TFA substantially reduces recalcitrance of crystalline cellulose to both enzymatic digestion and catalytic conversion. In a closed system to prevent loss of fluorohydrocarbons, the relative ease of recovery and regeneration of TFA by distillation makes it a potentially useful agent in large-scale deconstruction of biomass, not only for enzymatic depolymerization but also for enhancing rates of catalytic conversion to biofuel components and useful bio-products.« less

Cold tolerance of Littorinidae from southern Africa: intertidal snails are not constrained to freeze tolerance.

PubMed

Sinclair, Brent J; Marshall, David J; Singh, Sarika; Chown, Steven L

2004-11-01

All intertidal gastropods for which cold tolerance strategies have been assessed have been shown to be freeze tolerant. Thus, freeze tolerance is considered an adaptation to the intertidal environment. We investigated the cold tolerance strategies of three species of subtropical and temperate snails (Gastropoda: Littorinidae) to determine whether this group is phylogenetically constrained to freeze tolerance. We exposed 'dry' acclimated and 'wet' rehydrated snails to low temperatures to determine temperature of crystallisation (Tc), lower lethal temperature and LT(50) and to examine the relationship between ice formation and mortality. Tc was lowest in dry Afrolittorina knysnaensis (-13.6+/-0.4 degrees C), followed by dry Echinolittorina natalensis (-10.9+/-0.2 degrees C) and wet A. knysnaensis (-10.2+/-0.2 degrees C) . The Tc of both A. knysnaensis and E. natalensis increased with rehydration, whereas Tc of dry and wet Afrolittorina africana did not differ (-9.6+/-0.2 and -9.0+/-0.2 degrees C respectively). Wet snails of all species exhibited no or low survival of inoculative freezing, whereas dry individuals of A. knysnaensis could survive subzero temperatures above -8 degrees C when freezing was inoculated with ice . In the absence of external ice, Afrolittorina knysnaensis employs a freeze-avoidance strategy of cold tolerance, the first time this has been reported for an intertidal snail, indicating that there is no family-level phylogenetic constraint to freeze tolerance. Echinolittorina natalensis and A. africana both showed pre-freeze mortality and survival of some internal ice formation, but were not cold hardy in any strict sense.

The role of Southern Ocean mixing and upwelling in glacial-interglacial atmospheric CO2 change

NASA Astrophysics Data System (ADS)

Watson, Andrew J.; Naveira Garabato, Alberto C.

2006-02-01

Decreased ventilation of the Southern Ocean in glacial time is implicated in most explanations of lower glacial atmospheric CO2. Today, the deep (>2000 m) ocean south of the Polar Front is rapidly ventilated from below, with the interaction of deep currents with topography driving high mixing rates well up into the water column. We show from a buoyancy budget that mixing rates are high in all the deep waters of the Southern Ocean. Between the surface and ~2000 m depth, water is upwelled by a residual meridional overturning that is directly linked to buoyancy fluxes through the ocean surface. Combined with the rapid deep mixing, this upwelling serves to return deep water to the surface on a short time scale. We propose two new mechanisms by which, in glacial time, the deep Southern Ocean may have been more isolated from the surface. Firstly, the deep ocean appears to have been more stratified because of denser bottom water resulting from intense sea ice formation near Antarctica. The greater stratification would have slowed the deep mixing. Secondly, subzero atmospheric temperatures may have meant that the present-day buoyancy flux from the atmosphere to the ocean surface was reduced or reversed. This in turn would have reduced or eliminated the upwelling (contrary to a common assumption, upwelling is not solely a function of the wind stress but is coupled to the air-sea buoyancy flux too). The observed very close link between Antarctic temperatures and atmospheric CO2 could then be explained as a natural consequence of the connection between the air-sea buoyancy flux and upwelling in the Southern Ocean, if slower ventilation of the Southern Ocean led to lower atmospheric CO2. Here we use a box model, similar to those of previous authors, to show that weaker mixing and reduced upwelling in the Southern Ocean can explain the low glacial atmospheric CO2 in such a formulation.

Petroleum hydrocarbon biodegradation under seasonal freeze-thaw soil temperature regimes in contaminated soils from a sub-Arctic site.

PubMed

Chang, Wonjae; Klemm, Sara; Beaulieu, Chantale; Hawari, Jalal; Whyte, Lyle; Ghoshal, Subhasis

2011-02-01

Several studies have shown that biostimulation in ex situ systems such as landfarms and biopiles can facilitate remediation of petroleum hydrocarbon contaminated soils at sub-Arctic sites during summers when temperatures are above freezing. In this study, we examine the biodegradation of semivolatile (F2: C10-C16) and nonvolatile (F3: C16-C34) petroleum hydrocarbons and microbial respiration and population dynamics at post- and presummer temperatures ranging from -5 to 14 °C. The studies were conducted in pilot-scale tanks with soils obtained from a historically contaminated sub-Arctic site in Resolution Island (RI), Canada. In aerobic, nutrient-amended, unsaturated soils, the F2 hydrocarbons decreased by 32% during the seasonal freeze-thaw phase where soils were cooled from 2 to -5 °C at a freezing rate of -0.12 °C d(-1) and then thawed from -5 to 4 °C at a thawing rate of +0.16 °C d(-1). In the unamended (control) tank, the F2 fraction only decreased by 14% during the same period. Biodegradation of individual hydrocarbon compounds in the nutrient-amended soils was also confirmed by comparing their abundance over time to that of the conserved diesel biomarker, bicyclic sesquiterpanes (BS). During this period, microbial respiration was observed, even at subzero temperatures when unfrozen liquid water was detected during the freeze-thaw period. An increase in culturable heterotrophs and 16S rDNA copy numbers was noted during the freezing phase, and the (14)C-hexadecane mineralization in soil samples obtained from the nutrient-amended tank steadily increased. Hydrocarbon degrading bacterial populations identified as Corynebacterineae- and Alkanindiges-related strains emerged during the freezing and thawing phases, respectively, indicating there were temperature-based microbial community shifts.

Thermophysical properties of carboxylic and amino acid buffers at subzero temperatures: relevance to frozen state stabilization.

PubMed

Sundaramurthi, Prakash; Suryanarayanan, Raj

2011-06-02

Macromolecules and other thermolabile biologicals are often buffered and stored in frozen or dried (freeze-dried) state. Crystallization of buffer components in frozen aqueous solutions and the consequent pH shifts were studied in carboxylic (succinic, malic, citric, tartaric acid) and amino acid (glycine, histidine) buffers. Aqueous buffer solutions were cooled from room temperature (RT) to -25 °C and the pH of the solution was measured as a function of temperature. The thermal behavior of frozen solutions was investigated by differential scanning calorimetry (DSC), and the crystallized phases were identified by X-ray diffractometry (XRD). Based on the solubility of the neutral species of each buffer system over a range of temperatures, it was possible to estimate its degree of supersaturation at the subambient temperature of interest. This enabled us to predict its crystallization propensity in frozen systems. The experimental and the predicted rank orderings were in excellent agreement. The malate buffer system was robust with no evidence of buffer component crystallization and hence negligible pH shift. In the citrate and tartrate systems, at initial pH < pK(a)(2), only the most acidic buffer component (neutral form) crystallized on cooling, causing an increase in the freeze-concentrate pH. In glycine buffer solutions, when the initial pH was ∼3 units < isoelectric pH (pI = 5.9), β-glycine crystallization caused a small decrease in pH, while a similar effect but in the opposite direction was observed when the initial pH was ∼3 units > pI. In the histidine buffer system, depending on the initial pH, either histidine or histidine HCl crystallized.

Could behaviour and not physiological thermal tolerance determine winter survival of aphids in cereal fields?

PubMed

Alford, Lucy; Andrade, Thiago Oliveira; Georges, Romain; Burel, Françoise; van Baaren, Joan

2014-01-01

Traits of physiological thermotolerance are commonly measured in the laboratory as predictors of the field success of ectotherms at unfavourable temperatures (e.g. during harsh winters, heatwaves, or under conditions of predicted global warming). Due to being more complicated to measure, behavioural thermoregulation is less commonly studied, although both physiology and behaviour interact to explain the survival of ectotherms. The aphids Metopolophium dirhodum, Rhopalosiphum padi and Sitobion avenae are commercially important pests of temperate cereal crops. Although coexisting, these species markedly differ in winter success, with R. padi being the most abundant species during cold winters, followed by S. avenae and lastly M. dirhodum. To better understand the thermal physiology and behavioural factors contributing to differential winter success, the lethal temperature (physiological thermotolerance) and the behaviour of aphids in a declining temperature regime (behavioural thermotolerance) of these three species were investigated. Physiological thermotolerance significantly differed between the three species, with R. padi consistently the least cold tolerant and S. avenae the most cold tolerant. However, although the least cold tolerant of the study species, significantly more R. padi remained attached to the host plant at extreme sub-zero temperatures than S. avenae and M. dirhodum. Given the success of anholocyclic R. padi in harsh winters compared to its anholocyclic counterparts, this study illustrates that behavioural differences could be more important than physiological thermotolerance in explaining resistance to extreme temperatures. Furthermore it highlights that there is a danger to studying physiological thermotolerance in isolation when ascertaining risks of ectotherm invasions, the establishment potential of exotic species in glasshouses, or predicting species impacts under climate change scenarios.

Biological ice nucleation initiates hailstone formation

NASA Astrophysics Data System (ADS)

Michaud, Alexander B.; Dore, John E.; Leslie, Deborah; Lyons, W. Berry; Sands, David C.; Priscu, John C.

2014-11-01

Cloud condensation and ice nuclei in the troposphere are required precursors to cloud and precipitation formation, both of which influence the radiative balance of Earth. The initial stage of hailstone formation (i.e., the embryo) and the subsequent layered growth allow hail to be used as a model for the study of nucleation processes in precipitation. By virtue of the preserved particle and isotopic record captured by hailstones, they represent a unique form of precipitation that allows direct characterization of the particles present during atmospheric ice nucleation. Despite the ecological and economic consequences of hail storms, the dynamics of hailstone nucleation, and thus their formation, are not well understood. Our experiments show that hailstone embryos from three Rocky Mountain storms contained biological ice nuclei capable of freezing water at warm, subzero (°C) temperatures, indicating that biological particles can act as nucleation sites for hailstone formation. These results are corroborated by analysis of δD and δ18O from melted hailstone embryos, which show that the hailstones formed at similarly warm temperatures in situ. Low densities of ice nucleation active abiotic particles were also present in hailstone embryos, but their low concentration indicates they were not likely to have catalyzed ice formation at the warm temperatures determined from water stable isotope analysis. Our study provides new data on ice nucleation occurring at the bottom of clouds, an atmospheric region whose processes are critical to global climate models but which has challenged instrument-based measurements.

Supermacroprous chitosan–agarose–gelatin cryogels: in vitro characterization and in vivo assessment for cartilage tissue engineering

PubMed Central

Bhat, Sumrita; Tripathi, Anuj; Kumar, Ashok

2011-01-01

The study focuses on the synthesis of a novel polymeric scaffold having good porosity and mechanical characteristics synthesized by using natural polymers and their optimization for application in cartilage tissue engineering. The scaffolds were synthesized via cryogelation technology using an optimized ratio of the polymer solutions (chitosan, agarose and gelatin) and cross-linker followed by the incubation at sub-zero temperature (−12°C). Microstructure examination of the chitosan–agarose–gelatine (CAG) cryogels was done using scanning electron microscopy (SEM) and fluorescent microscopy. Mechanical analysis, such as the unconfined compression test, demonstrated that cryogels with varying chitosan concentrations, i.e. 0.5–1% have a high compression modulus. In addition, fatigue tests revealed that scaffolds are suitable for bioreactor studies where gels are subjected to continuous cyclic strain. In order to confirm the stability, cryogels were subjected to high frequency (5 Hz) with 30 per cent compression of their original length up to 1 × 105 cycles, gels did not show any significant changes in their mass and dimensions during the experiment. These cryogels have exhibited degradation capacity under aseptic conditions. CAG cryogels showed good cell adhesion of primary goat chondrocytes examined by SEM. Cytotoxicity of the material was checked by MTT assay and results confirmed the biocompatibility of the material. In vivo biocompatibility of the scaffolds was checked by the implantation of the scaffolds in laboratory animals. These results suggest the potential of CAG cryogels as a good three-dimensional scaffold for cartilage tissue engineering. PMID:20943683

Distinct microbial communities associated with buried soils in the Siberian tundra

PubMed Central

Gittel, Antje; Bárta, Jiří; Kohoutová, Iva; Mikutta, Robert; Owens, Sarah; Gilbert, Jack; Schnecker, Jörg; Wild, Birgit; Hannisdal, Bjarte; Maerz, Joeran; Lashchinskiy, Nikolay; Čapek, Petr; Šantrůčková, Hana; Gentsch, Norman; Shibistova, Olga; Guggenberger, Georg; Richter, Andreas; Torsvik, Vigdis L; Schleper, Christa; Urich, Tim

2014-01-01

Cryoturbation, the burial of topsoil material into deeper soil horizons by repeated freeze–thaw events, is an important storage mechanism for soil organic matter (SOM) in permafrost-affected soils. Besides abiotic conditions, microbial community structure and the accessibility of SOM to the decomposer community are hypothesized to control SOM decomposition and thus have a crucial role in SOM accumulation in buried soils. We surveyed the microbial community structure in cryoturbated soils from nine soil profiles in the northeastern Siberian tundra using high-throughput sequencing and quantification of bacterial, archaeal and fungal marker genes. We found that bacterial abundances in buried topsoils were as high as in unburied topsoils. In contrast, fungal abundances decreased with depth and were significantly lower in buried than in unburied topsoils resulting in remarkably low fungal to bacterial ratios in buried topsoils. Fungal community profiling revealed an associated decrease in presumably ectomycorrhizal (ECM) fungi. The abiotic conditions (low to subzero temperatures, anoxia) and the reduced abundance of fungi likely provide a niche for bacterial, facultative anaerobic decomposers of SOM such as members of the Actinobacteria, which were found in significantly higher relative abundances in buried than in unburied topsoils. Our study expands the knowledge on the microbial community structure in soils of Northern latitude permafrost regions, and attributes the delayed decomposition of SOM in buried soils to specific microbial taxa, and particularly to a decrease in abundance and activity of ECM fungi, and to the extent to which bacterial decomposers are able to act as their functional substitutes. PMID:24335828

The relationship between gut contents and supercooling capacity in hatchling painted turtles (Chrysemys picta).

PubMed

Packard, Gary C; Packard, Mary J

2006-05-01

Painted turtles (Chrysemys picta) typically spend their first winter of life in a shallow, subterranean hibernaculum (the natal nest) where they seemingly withstand exposure to ice and cold by resisting freezing and becoming supercooled. However, turtles ingest soil and fragments of eggshell as they are hatching from their eggs, and the ingestate usually contains efficient nucleating agents that cause water to freeze at high subzero temperatures. Consequently, neonatal painted turtles have only a modest ability to undergo supercooling in the period immediately after hatching. We studied the limit for supercooling (SCP) in hatchlings that were acclimating to different thermal regimes and then related SCPs of the turtles to the amount of particulate matter in their gastrointestinal (GI) tract. Turtles that were transferred directly from 26 degrees C (the incubation temperature) to 2 degrees C did not purge soil from their gut, and SCPs for these animals remained near -4 degrees C for the 60 days of the study. Animals that were held at 26 degrees C for the duration of the experiment usually cleared soil from their GI tract within 24 days, but SCPs for these turtles were only slightly lower after 60 days than they were at the outset of the experiment. Hatchlings that were acclimating slowly to 2 degrees C cleared soil from their gut within 24 days and realized a modest reduction in their SCP. However, the limit of supercooling in the slowly acclimating animals continued to decline even after all particulate material had been removed from their GI tract, thereby indicating that factors intrinsic to the nucleating agents themselves also may have been involved in the acclimation of hatchlings to low temperature. The lowest SCPs for turtles that were acclimating slowly to 2 degrees C were similar to SCPs recorded in an earlier study of animals taken from natural nests in late autumn, so the current findings affirm the importance of seasonally declining temperatures in preparing animals in the field to withstand conditions that they will encounter during winter.

Reducing the loss of vaccines from accidental freezing in the cold chain: the experience of continuous temperature monitoring in Tunisia.

PubMed

Lloyd, John; Lydon, Patrick; Ouhichi, Ramzi; Zaffran, Michel

2015-02-11

Accidental freezing of vaccines is a growing threat and a real risk for national immunization programs when the potency of many vaccines can be compromised if these are exposed to sub-zero temperatures in the cold chain. In Tunisia, this issue is compounded by using sub-standard domestic cold chain equipment instead of equipping the program with medical refrigerators designed specifically for storing vaccines and temperature sensitive pharmaceuticals. Against this backdrop, this paper presents the findings of a demonstration project conducted in Tunisia in 2012 that tested the impact of introducing several freeze prevention solutions to mitigate the risk of accidental freezing of vaccines. The main finding is that, despite the continued use of underperforming domestic refrigerators, continuous temperature monitoring using new technologies combined with other technological interventions significantly reduced the prevalence of accidental exposure to freezing temperatures. These improvements were noticed for cold chain storage at regional, district and health center levels, and during the transport legs that were part of the demonstration conducted in the regions of Kasserine in the South-Eastern part of Tunisia. Subsequent to introducing these freeze prevention solutions, the incidence of freeze alarms was reduced and the percent of time the temperatures dropped below the 2 °C recommended threshold. The incidence of freeze alarms at health center level was reduced by 40%. Lastly, the solutions implemented reduced risk of freezing during transport from 13.8% to 1.7%. Although the solution implemented is not optimal in the longer term because domestic refrigerators are used extensively in district stores and health centers, the risk of accidental freezing is significantly reduced by introducing the practice of continuous temperature monitoring as a standard. The management of the cold chain equipment was strengthened as a result which helps protect the potency of vaccines to the areas of most difficult access. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Monitoring an Induced Permafrost Warming Experiment Using ERT, Temperature, and NMR in Fairbanks, Alaska

NASA Astrophysics Data System (ADS)

Ulrich, C.; Ajo Franklin, J. B.; Ekblaw, I.; Lindsey, N.; Wagner, A. M.; Saari, S.; Daley, T. M.; Freifeld, B. M.

2016-12-01

As global temperatures continue to rise, permafrost landscapes will experience more rapid changes than other global climate zones. Permafrost thaw is a result of increased temperatures in arctic settings resulting in surface deformation and subsurface hydrology changes. From an engineering perspective, surface deformation poses a threat to the stability of existing infrastructure such as roads, utility piping, and building structures. Preemptively detecting or monitoring subsurface thaw dynamics presents a difficult challenge due to the long time scales as deformation occurs. Increased subsurface moisture content results from permafrost thaw of which electrical resistivity tomography (ERT), soil temperature, and nuclear magnetic resonance (NMR) are directly sensitive. In this experiment we evaluate spatial and temporal changes in subsurface permafrost conditions (moisture content and temperature) at a experimental heating plot in Fairbanks, AK. This study focuses on monitoring thaw signatures using multiple collocated electrical resistivity (ERT), borehole temperature, and borehole nuclear magnetic resonance (NMR) measurements. Timelapse ERT (sensitive to changes in moisture content) was inverted using collocated temperature and NMR to constrain ERT inversions. Subsurface thermal state was monitored with timelapse thermistors, sensitive to soil ice content. NMR was collected in multiple boreholes and is sensitive to changes in moisture content and pore scale distribution. As permafrost thaws more hydrogen, in the form of water, is available resulting in a changing NMR response. NMR requires the availability of liquid water in order to induce spin of the hydrogen molecule, hence, if frozen water molecules will be undetectable. In this study, the permafrost is poised close to 0oC and is mainly silt with small pore dimensions; this combination makes NMR particularly useful due to the possibility of sub-zero thaw conditions within the soil column. Overall this experiment presents a complementary suite of methods that provides feedback on subsurface permafrost state even in cases where soil texture might control unfrozen water content.

Influence of antifreeze proteins on the ice/water interface.

PubMed

Todde, Guido; Hovmöller, Sven; Laaksonen, Aatto

2015-02-26

Antifreeze proteins (AFP) are responsible for the survival of several species, ranging from bacteria to fish, that encounter subzero temperatures in their living environment. AFPs have been divided into two main families, moderately and hyperactive, depending on their thermal hysteresis activity. We have studied one protein from both families, the AFP from the snow flea (sfAFP) and from the winter flounder (wfAFP), which belong to the hyperactive and moderately active family, respectively. On the basis of molecular dynamics simulations, we have estimated the thickness of the water/ice interface for systems both with and without the AFPs attached onto the ice surface. The calculation of the diffusion profiles along the simulation box allowed us to measure the interface width for different ice planes. The obtained widths clearly show a different influence of the two AFPs on the ice/water interface. The different impact of the AFPs here studied on the interface thickness can be related to two AFPs properties: the protein hydrophobic surface and the number of hydrogen bonds that the two AFPs faces form with water molecules.

PLA and two components silicon rubber blends aiming for frozen foods packaging applications

NASA Astrophysics Data System (ADS)

Meekum, Utai; Khiansanoi, Apichart

2018-03-01

Designing of PLA and two components silicone rubber blends was studies. Frozen food packaging application is the main ultimate aim. The statistical method using 23 DOE was conducted. The standard testing methods, in particular impact testing at sub-zero temperature, were performed. The preliminary blend formula comprised 1.0 phr of silane and polyester polyols, respectively, was initially resolved. Then, the optimize the silicone portion in the blends was determined. Blending formula using 8.0 phr of silicone with respect to PLA matrix gave rise to the overall satisfactory properties. 3. TETA was used as the silicone curing agent and reactively blended onto the ingredients. TETA at 0.4 phr, with respect to the silicone, enhanced the mechanical properties, especially flexibility and toughness, of the PLA/silicone blend. Exceeding the optimal TETA loading would cause the chain scission and also the dilution effects. Hence, marginal inferior properties of the blends were be experienced. The preliminary biodegradability investigation found that the PLA/silicone blend initially triggered at the second week. Its degradation rate was likely to be faster than neat PLA.

Microbial taxonomic diversity and adaptation mechanisms in lithic ecosystems of the northern Victoria Land, Antarctica

NASA Astrophysics Data System (ADS)

Kim, O. S.; Lee, J.; Cho, J. H.; Kwon, M.; Cho, A.; Kim, M.; Woo, J.; Hong, S. G.; Lee, J.

2016-12-01

Rock is one of the best habitat for microorganisms in Antarctica, providing the good condition to avoid strong sunlight and wind. Furthermore, geochemistry in rock can provide as nutrients for microorganisms. Barren rock can be considered as an ecosystem by fouling, which is defined as the settlement of organisms and their growth. These life forms have the specialized mechanism to adapt the harsh environmental conditions such as a below subzero temperature, a unique annual light/dark cycle, wind chill and limited water availability and nutrient supply. However, little is known about the microbial communities and their adaptation mechanisms in this harsh environments. In this study, we focus on the microbial ecology in order to understand what kind of microorganisms are present based on culture-dependent and -independent methods collected barren rock samples from the northern Victoria Land, Antarctica. Additionally, we present the complete genome sequence of Cryobacterium arcticum PAMC 27867, one of the isolates from these rock samples, in order to understand the microbial adaptation strategies in lithic ecosystems, Antarctica.

Diversity and community structure of fungi through a permafrost core profile from the Qinghai-Tibet Plateau of China.

PubMed

Hu, Weigang; Zhang, Qi; Li, Dingyao; Cheng, Gang; Mu, Jing; Wu, Qingbai; Niu, Fujun; An, Lizhe; Feng, Huyuan

2014-12-01

While a vast number of studies have addressed the prokaryotic diversity in permafrost, characterized by subzero temperatures, low water activity, and extremely low rates of nutrient and metabolite transfer, fungal patterns have received surprisingly limited attention. Here, the fungal diversity and community structure were investigated by culture-dependent technique combined with cloning-restriction fragment length polymorphism (RFLP) analysis of sediments in a 10-m-long permafrost core from the Qinghai-Tibet Plateau of China. A total of 62 fungal phylotypes related to 10 distinct classes representing three phyla were recovered from 5031 clones generated in 13 environmental gene libraries. A large proportion of the phylotypes (25/62) that were distantly related to described fungal species appeared to be novel diversity. Ascomycota was the predominant group of fungi, with respect to both clone and phylotype number. Our results suggested there was the existence of cosmopolitan psychrophilic or psychrotolerant fungi in permafrost sediments, the community composition of fungi varied with increasing depth, while these communities largely distributed according to core layers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PELS (Planetary Environmental Liquid Simulator): a new type of simulation facility to study extraterrestrial aqueous environments.

PubMed

Martin, Derek; Cockell, Charles S

2015-02-01

Investigations of other planetary bodies, including Mars and icy moons such as Enceladus and Europa, show that they may have hosted aqueous environments in the past and may do so even today. Therefore, a major challenge in astrobiology is to build facilities that will allow us to study the geochemistry and habitability of these extraterrestrial environments. Here, we describe a simulation facility (PELS: Planetary Environmental Liquid Simulator) with the capability for liquid input and output that allows for the study of such environments. The facility, containing six separate sample vessels, allows for statistical replication of samples. Control of pressure, gas composition, UV irradiation conditions, and temperature allows for the precise replication of aqueous conditions, including subzero brines under martian atmospheric conditions. A sample acquisition system allows for the collection of both liquid and solid samples from within the chamber without breaking the atmospheric conditions, enabling detailed studies of the geochemical evolution and habitability of past and present extraterrestrial environments. The facility we describe represents a new frontier in planetary simulation-continuous flow-through simulation of extraterrestrial aqueous environments.

The Structure of Resting Bacterial Populations in Soil and Subsoil Permafrost

NASA Astrophysics Data System (ADS)

Soina, Vera S.; Mulyukin, Andrei L.; Demkina, Elena V.; Vorobyova, Elena A.; El-Registan, Galina I.

2004-09-01

The structure of individual cells in microbial populations in situ of the Arctic and Antarctic permafrost was studied by scanning and transmission electron microscopy methods and compared with that of cyst-like resting forms generated under special conditions by the non-sporeforming bacteria Arthrobacter and Micrococcus isolated from the permafrost. Electron microscopy examination of microorganisms in situ revealed several types of bacterial cells having no signs of damage, including "dwarf" curved forms similar to nanoforms. Intact bacterial cells in situ and frozen cultures of the permafrost isolates differed from vegetative cells by thickened cell walls, the altered structure of cytoplasm, and the compact nucleoid, and were similar in these features to cyst-like resting forms of non-spore-forming "permafrost" bacterial strains of Arthrobacter and Micrococcus spp. Cyst-like cells, being resistant to adverse external factors, are regarded as being responsible for survival of the non-spore-formers under prolonged exposure to subzero temperatures and can be a target to search for living microorganisms in natural environments both on the Earth and on extraterrestrial bodies.

Is warmer better? Decreased oxidative damage in notothenioid fish after long-term acclimation to multiple stressors.

PubMed

Enzor, Laura A; Place, Sean P

2014-09-15

Antarctic fish of the suborder Notothenioidei have evolved several unique adaptations to deal with subzero temperatures. However, these adaptations may come with physiological trade-offs, such as an increased susceptibility to oxidative damage. As such, the expected environmental perturbations brought on by global climate change have the potential to significantly increase the level of oxidative stress and cellular damage in these endemic fish. Previous single stressor studies of the notothenioids have shown they possess the capacity to acclimate to increased temperatures, but the cellular-level effects remain largely unknown. Additionally, there is little information on the ability of Antarctic fish to respond to ecologically relevant environmental changes where multiple variables change concomitantly. We have examined the potential synergistic effects that increased temperature and Ṗ(CO2) have on the level of protein damage in Trematomus bernacchii, Pagothenia borchgrevinki and Trematomus newnesi, and combined these measurements with changes in total enzymatic activity of catalase (CAT) and superoxide dismutase (SOD) in order to gauge tissue-specific changes in antioxidant capacity. Our findings indicate that total SOD and CAT activity levels displayed only small changes across treatments and tissues. Short-term acclimation to decreased seawater pH and increased temperature resulted in significant increases in oxidative damage. Surprisingly, despite no significant change in antioxidant capacity, cellular damage returned to near-basal levels, and significantly decreased in T. bernacchii, after long-term acclimation. Overall, these data suggest that notothenioid fish currently maintain the antioxidant capacity necessary to offset predicted future ocean conditions, but it remains unclear whether this capacity comes with physiological trade-offs. © 2014. Published by The Company of Biologists Ltd.

Deep-sequencing transcriptome analysis of field-grown Medicago sativa L. crown buds acclimated to freezing stress.

PubMed

Song, Lili; Jiang, Lin; Chen, Yue; Shu, Yongjun; Bai, Yan; Guo, Changhong

2016-09-01

Medicago sativa L. (alfalfa) 'Zhaodong' is an important forage legume that can safely survive in northern China where winter temperatures reach as low as -30 °C. Survival of alfalfa following freezing stress depends on the amount and revival ability of crown buds. In order to investigate the molecular mechanisms of frost tolerance in alfalfa, we used transcriptome sequencing technology and bioinformatics strategies to analyze crown buds of field-grown alfalfa during winter. We statistically identified a total of 5605 differentially expressed genes (DEGs) involved in freezing stress including 1900 upregulated and 3705 downregulated DEGs. We validated 36 candidate DEGs using qPCR to confirm the accuracy of the RNA-seq data. Unlike other recent studies, this study employed alfalfa plants grown in the natural environment. Our results indicate that not only the CBF orthologs but also membrane proteins, hormone signal transduction pathways, and ubiquitin-mediated proteolysis pathways indicate the presence of a special freezing adaptation mechanism in alfalfa. The antioxidant defense system may rapidly confer freezing tolerance to alfalfa. Importantly, biosynthesis of secondary metabolites and phenylalanine metabolism, which is of potential importance in coordinating freezing tolerance with growth and development, were downregulated in subzero temperatures. The adaptive mechanism for frost tolerance is a complex multigenic process that is not well understood. This systematic analysis provided an in-depth view of stress tolerance mechanisms in alfalfa.

Reversible adsorption of catalase onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogels.

PubMed

Aktaş Uygun, Deniz; Uygun, Murat; Akgöl, Sinan; Denizli, Adil

2015-05-01

In this presented study, poly(acrylamide-glycidyl methacrylate) [poly(AAm-GMA)] cryogels were synthesized by cryopolymerization technique at sub-zero temperature. Prepared cryogels were then functionalized with iminodiacetic acid (IDA) and chelated with Fe(3+) ions in order produce the metal chelate affinity matrix. Synthesized cryogels were characterized with FTIR, ESEM and EDX analysis, and it was found that the cryogel had sponge like structure with interconnected pores and their pore diameter was about 200 μm. Fe(3+) chelated poly(AAm-GMA)-IDA cryogels were used for the adsorption of catalase and optimum adsorption conditions were determined by varying the medium pH, initial catalase concentration, temperature and ionic strength. Maximum catalase adsorption onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was found to be 12.99 mg/g cryogel at 25 °C, by using pH 5.0 acetate buffer. Adsorbed catalase was removed from the cryogel by using 1.0M of NaCl solution and desorption yield was found to be 96%. Additionally, reusability profile of the Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was also investigated and it was found that, adsorption capacity of the cryogels didn't decrease significantly at the end of the 40 reuses. Catalase activity studies were also tested and it was demonstrated that desorbed catalase retained 70% of its initial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Low temperature stress modulated secretome analysis and purification of antifreeze protein from Hippophae rhamnoides, a Himalayan wonder plant.

PubMed

Gupta, Ravi; Deswal, Renu

2012-05-04

Plants' distribution and productivity are adversely affected by low temperature (LT) stress. LT induced proteins were analyzed by 2-DE-nano-LC-MS/MS in shoot secretome of Hippophae rhamnoides (seabuckthorn), a Himalayan wonder shrub. Seedlings were subjected to direct freezing stress (-5 °C), cold acclimation (CA), and subzero acclimation (SZA), and extracellular proteins (ECPs) were isolated using vacuum infiltration. Approximately 245 spots were reproducibly detected in 2-DE gels of LT treated secretome, out of which 61 were LT responsive. Functional categorization of 34 upregulated proteins showed 47% signaling, redox regulated, and defense associated proteins. LT induced secretome contained thaumatin like protein and Chitinase as putative antifreeze proteins (AFPs). Phase contrast microscopy with a nanoliter osmometer showed hexagonal ice crystals with 0.13 °C thermal hysteresis (TH), and splat assay showed 1.5-fold ice recrystallization inhibition (IRI), confirming antifreeze activity in LT induced secretome. A 41 kDa polygalacturonase inhibitor protein (PGIP), purified by ice adsorption chromatography (IAC), showed hexagonal ice crystals, a TH of 0.19 °C, and 9-fold IRI activity. Deglycosylated PGIP retained its AFP activity, suggesting that glycosylation is not required for AFP activity. This is the first report of LT modulated secretome analysis and purification of AFPs from seabuckthorn. Overall, these findings provide an insight in probable LT induced signaling in the secretome.

Harnessing hyperthermostable lactonase from Sulfolobus solfataricus for biotechnological applications

PubMed Central

Rémy, Benjamin; Plener, Laure; Poirier, Laetitia; Elias, Mikael; Daudé, David; Chabrière, Eric

2016-01-01

Extremozymes have gained considerable interest as they could meet industrial requirements. Among these, SsoPox is a hyperthermostable enzyme isolated from the archaeon Sulfolobus solfataricus. This enzyme is a lactonase catalyzing the hydrolysis of acyl-homoserine lactones; these molecules are involved in Gram-negative bacterial communication referred to as quorum sensing. SsoPox exhibits promiscuous phosphotriesterase activity for the degradation of organophosphorous chemicals including insecticides and chemical warfare agents. Owing to its bi-functional catalytic abilities as well as its intrinsic stability, SsoPox is appealing for many applications, having potential uses in the agriculture, defense, food and health industries. Here we investigate the biotechnological properties of the mutant SsoPox-W263I, a variant with increased lactonase and phosphotriesterase activities. We tested enzyme resistance against diverse process-like and operating conditions such as heat resistance, contact with organic solvents, sterilization, storage and immobilization. Bacterial secreted materials from both Gram-negative and positive bacteria were harmless on SsoPox-W263I activity and could reactivate heat-inactivated enzyme. SsoPox showed resistance to harsh conditions demonstrating that it is an extremely attractive enzyme for many applications. Finally, the potential of SsoPox-W263I to be active at subzero temperature is highlighted and discussed in regards to the common idea that hyperthermophile enzymes are nearly inactive at low temperatures. PMID:27876889

Heterologous expression of antifreeze protein gene AnAFP from Ammopiptanthus nanus enhances cold tolerance in Escherichia coli and tobacco.

PubMed

Deng, Long-Qun; Yu, Hao-Qiang; Liu, Yan-Ping; Jiao, Pei-Pei; Zhou, Shu-Feng; Zhang, Su-Zhi; Li, Wan-Chen; Fu, Feng-Ling

2014-04-10

Antifreeze proteins are a class of polypeptides produced by certain animals, plants, fungi and bacteria that permit their survival under the subzero environments. Ammopiptanthus nanus is the unique evergreen broadleaf bush endemic to the Mid-Asia deserts. It survives at the west edge of the Tarim Basin from the disappearance of the ancient Mediterranean in the Tertiary Period. Its distribution region is characterized by the arid climate and extreme temperatures, where the extreme temperatures range from -30 °C to 40 °C. In the present study, the antifreeze protein gene AnAFP of A. nanus was used to transform Escherichia coli and tobacco, after bioinformatics analysis for its possible function. The transformed E. coli strain expressed the heterologous AnAFP gene under the induction of isopropyl β-D-thiogalactopyranoside, and demonstrated significant enhancement of cold tolerance. The transformed tobacco lines expressed the heterologous AnAFP gene in response to cold stress, and showed a less change of relative electrical conductivity under cold stress, and a less wilting phenotype after 16 h of -3 °C cold stress and thawing for 1h than the untransformed wild-type plants. All these results imply the potential value of the AnAFP gene to be used in genetic modification of commercially important crops for improvement of cold tolerance. Copyright © 2014 Elsevier B.V. All rights reserved.

The Temperature of Intracellular Ice Formation in Mouse Oocytes vs. the Unfrozen Fraction at that Temperature ⋆

PubMed Central

Mazur, Peter; Pinn, Irina L.; Kleinhans, F.W.

2009-01-01

We have previously reported [11] that intracellular ice formation (IIF) in mouse oocytes suspended in various concentrations of glycerol and ethylene glycol (EG) occurs at temperatures where the percentage of unfrozen water is about 6% and 12% respectively even though the IIF temperatures varied from −14° to −41°C. However, because of the way the solutions were prepared, the concentrations of salt and glycerol or EG in that unfrozen fraction at IIF were also rather tightly grouped. The experiments reported in the present paper were designed to separate the effects of the unfrozen fraction at IIF from that of the solute concentration in the unfrozen fraction. This separation makes use of two facts. One is that the concentration of solutes in the residual liquid at a given subzero temperature is fixed regardless of their concentration in the initial unfrozen solution. However, second, the fraction unfrozen at a given temperature is dependent on the initial solute concentration. Experimentally, oocytes were suspended in solutions of glycerol/buffered saline and EG/buffered saline of varying total solute concentration with the restriction that the mass ratio of glycerol and EG to salts are held constant. The oocytes were then cooled rapidly enough (20°C/min) to avoid significant osmotic shrinkage, and the temperature at which IIF occurred as noted. When this is done, we find, as previously that the fraction of water remaining unfrozen at the temperature of IIF remains nearly constant at 5 to 8% for both glycerol and EG even though the IIF temperatures vary from −14°C to −50°C. But unlike the previous results, the salt and CPA concentrations in the unfrozen fraction vary by a factor of three. The present procedure for preparing the solutions produces a potentially complicating factor; namely, the cell volumes vary substantially prior to freezing: Substantially greater than isotonic in some solution; substantially smaller in others. However, the data in toto demonstrate that cell volume is not a determining factor in the IIF temperature. PMID:17379206

The temperature of intracellular ice formation in mouse oocytes vs. the unfrozen fraction at that temperature.

PubMed

Mazur, Peter; Pinn, Irina L; Kleinhans, F W

2007-04-01

We have previously reported [Cryobiology 51 (2005) 29-53] that intracellular ice formation (IIF) in mouse oocytes suspended in various concentrations of glycerol and ethylene glycol (EG) occurs at temperatures where the percentage of unfrozen water is about 6% and 12%, respectively, even though the IIF temperatures varied from -14 to -41 degrees C. However, because of the way the solutions were prepared, the concentrations of salt and glycerol or EG in that unfrozen fraction at IIF were also rather tightly grouped. The experiments reported in the present paper were designed to separate the effects of the unfrozen fraction at IIF from that of the solute concentration in the unfrozen fraction. This separation makes use of two facts. One is that the concentration of solutes in the residual liquid at a given subzero temperature is fixed regardless of their concentration in the initial unfrozen solution. However, second, the fraction unfrozen at a given temperature is dependent on the initial solute concentration. Experimentally, oocytes were suspended in solutions of glycerol/buffered saline and EG/buffered saline of varying total solute concentration with the restriction that the mass ratios of glycerol and EG to salts are held constant. The oocytes were then cooled rapidly enough (20 degrees C/min) to avoid significant osmotic shrinkage, and the temperature at which IIF occurred was noted. When this is done, we find, as previously that the fraction of water remaining unfrozen at the temperature of IIF remains nearly constant at 5-8% for both glycerol and EG even though the IIF temperatures vary from -14 to -50 degrees C. But unlike the previous results, the salt and CPA concentrations in the unfrozen fraction vary by a factor of three. The present procedure for preparing the solutions produces a potentially complicating factor; namely, the cell volumes vary substantially prior to freezing: substantially greater than isotonic in some solutions; substantially smaller in others. However, the data in toto demonstrate that cell volume is not a determining factor in the IIF temperature.

Studies on the Effect of Sub-zero Temperatures on the Formation of Extremely Low Volatility Dimer Esters in Secondary Organic Aerosol from Alpha-Pinene

NASA Astrophysics Data System (ADS)

Kristensen, Kasper; Normann Jensen, Louise; Bilde, Merete

2016-04-01

The oxidation of volatile organic compounds (VOC) is considered a major source of secondary organic aerosols (SOA) in the atmosphere. Recently, extremely low volatility organic compounds, or ELVOC, formed from the oxidation of VOCs have been shown to play a crucial role in new particle formation (Ehn et al., 2014). In addition, higher molecular weight dimer esters originating from the oxidation of the biogenic VOC alpha-pinene have been observed in both laboratory-generated and ambient SOA (Kristensen et al., 2013). The low volatility of the dimer esters along with an observed rapid formation makes these high molecular weight compounds likely candidates involved in new particle formation from the oxidation of alpha-pinene. Furthermore, laboratory experiments show that the dimer esters only form in the presence of ozone, thus may be used as tracers for the ozone-initiated oxidation of alpha-pinene, and are therefore indicative of enhanced anthropogenic activities. In this work, we present the results of a series of oxidation experiments performed in the newly constructed cold-room smog chamber at Aarhus University. This unique and state-of-the-art Teflon chamber allows for atmospheric simulations of the oxidation VOCs and subsequent SOA formation at temperatures down to -16 °C. In this study, ozonolysis and photochemical oxidations of alpha-pinene are performed at temperatures ranging from +20 to -16 °C. Chemical characterization of the formed SOA is performed using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. The results show significant differences in the chemical composition related to the experiment temperature. In particularly, the concentration of the high molecular weight dimer esters showed to be highly affected by temperature. Interestingly, preliminary results show higher formation of dimer esters related to increased SOA formation rate, thus indicating that these particle-phase ELVOCs may be linked with new particle formation. Ehn, M., Thornton, J. A., Kleist, E., Sipila, M., Junninen, H., Pullinen, I., Springer, M., Rubach, F., Tillmann, R., Lee, B., Lopez-Hilfiker, F., Andres, S., Acir, I. H., Rissanen, M., Jokinen, T., Schobesberger, S., Kangasluoma, J., Kontkanen, J., Nieminen, T., Kurten, T., Nielsen, L. B., Jorgensen, S., Kjaergaard, H. G., Canagaratna, M., Dal Maso, M., Berndt, T., Petaja, T., Wahner, A., Kerminen, V. M., Kulmala, M., Worsnop, D. R., Wildt, J., and Mentel, T. F.: A large source of low-volatility secondary organic aerosol, Nature, 506, 476-+, 10.1038/nature13032, 2014. Kristensen, K., Enggrob, K. L., King, S. M., Worton, D. R., Platt, S. M., Mortensen, R., Rosenoern, T., Surratt, J. D., Bilde, M., Goldstein, A. H., and Glasius, M.: Formation and occurrence of dimer esters of pinene oxidation products in atmospheric aerosols, Atmospheric Chemistry and Physics, 13, 3763-3776, 2013.

Free and total thyroid hormones in humans at extreme altitude

NASA Astrophysics Data System (ADS)

Basu, Minakshi; Pal, K.; Malhotra, A. S.; Prasad, R.; Sawhney, R. C.

1995-03-01

Alterations in circulatory levels of total T4 (TT4), total T3 (TT3), free T4 (FT4), free T3 (FT3), thyrotropin (TSH) and T3 uptake (T3U) were studied in male and female sea-level residents (SLR) at sea level, in Armed forces personnel staying at high altitude (3750 m) for prolonged duration (acclimatized lowlanders, ALL) and in high-altitude natives (HAN). Identical studies were also performed on male ALL who trekked to an extreme altitude of 5080 m and stayed at an altitude of more than 6300 m for about 6 months. The total as well as free thyroid hormones were found to be significantly higher in ALL and HAN as compared to SLR values. Both male as well as female HAN had higher levels of thyroid hormones. The rise in hormone levels in different ALL ethnic groups drawn from amongst the southern and northern parts of the country was more or less identical. In both HAN and ALL a decline in FT3 and FT4 occurred when these subjects trekked at subzero temperatures to extreme altitude of 5080 m but the levels were found to be higher in ALL who stayed at 6300 m for a prolonged duration. Plasma TSH did not show any appreciable change at lower altitudes but was found to be decreased at extreme altitude. The increase in thyroid hormones at high altitude was not due to an increase in hormone binding proteins, since T3U was found to be higher at high altitudes. A decline in TSH and hormone binding proteins and an increase in the free moiety of the hormones is indicative of a subtle degree of tissue hyperthyroidism which may be playing an important role in combating the extreme cold and hypoxic environment of high altitudes.

Preservation of Differentiation and Clonogenic Potential of Human Hematopoietic Stem and Progenitor Cells during Lyophilization and Ambient Storage

PubMed Central

Buchanan, Sandhya S.; Pyatt, David W.; Carpenter, John F.

2010-01-01

Progenitor cell therapies show great promise, but their potential for clinical applications requires improved storage and transportation. Desiccated cells stored at ambient temperature would provide economic and practical advantages over approaches employing cell freezing and subzero temperature storage. The objectives of this study were to assess a method for loading the stabilizing sugar, trehalose, into hematopoietic stem and progenitor cells (HPC) and to evaluate the effects of subsequent freeze-drying and storage at ambient temperature on differentiation and clonogenic potential. HPC were isolated from human umbilical cord blood and loaded with trehalose using an endogenous cell surface receptor, termed P2Z. Solution containing trehalose-loaded HPC was placed into vials, which were transferred to a tray freeze-dryer and removed during each step of the freeze-drying process to assess differentiation and clonogenic potential. Control groups for these experiments were freshly isolated HPC. Control cells formed 1450±230 CFU-GM, 430±140 BFU-E, and 50±40 CFU-GEMM per 50 µL. Compared to the values for the control cells, there was no statistical difference observed for cells removed at the end of the freezing step or at the end of primary drying. There was a gradual decrease in the number of CFU-GM and BFU-E for cells removed at different temperatures during secondary drying; however, there were no significant differences in the number of CFU-GEMM. To determine storage stability of lyophilized HPC, cells were stored for 4 weeks at 25°C in the dark. Cells reconstituted immediately after lyophilization produced 580±90 CFU-GM (∼40%, relative to unprocessed controls p<0.0001), 170±70 BFU-E (∼40%, p<0.0001), and 41±22 CFU-GEMM (∼82%, p = 0.4171), and cells reconstituted after 28 days at room temperature produced 513±170 CFU-GM (∼35%, relative to unprocessed controls, p<0.0001), 112±68 BFU-E (∼26%, p<0.0001), and 36±17 CFU-GEMM (∼82%, p = 0.2164) These studies are the first to document high level retention of CFU-GEMM following lyophilization and storage for 4 weeks at 25°C. This type of flexible storage stability would potentially permit the ability to ship and store HPC without the need for refrigeration. PMID:20824143

Preservation of differentiation and clonogenic potential of human hematopoietic stem and progenitor cells during lyophilization and ambient storage.

PubMed

Buchanan, Sandhya S; Pyatt, David W; Carpenter, John F

2010-09-01

Progenitor cell therapies show great promise, but their potential for clinical applications requires improved storage and transportation. Desiccated cells stored at ambient temperature would provide economic and practical advantages over approaches employing cell freezing and subzero temperature storage. The objectives of this study were to assess a method for loading the stabilizing sugar, trehalose, into hematopoietic stem and progenitor cells (HPC) and to evaluate the effects of subsequent freeze-drying and storage at ambient temperature on differentiation and clonogenic potential. HPC were isolated from human umbilical cord blood and loaded with trehalose using an endogenous cell surface receptor, termed P2Z. Solution containing trehalose-loaded HPC was placed into vials, which were transferred to a tray freeze-dryer and removed during each step of the freeze-drying process to assess differentiation and clonogenic potential. Control groups for these experiments were freshly isolated HPC. Control cells formed 1450+/-230 CFU-GM, 430+/-140 BFU-E, and 50+/-40 CFU-GEMM per 50 microL. Compared to the values for the control cells, there was no statistical difference observed for cells removed at the end of the freezing step or at the end of primary drying. There was a gradual decrease in the number of CFU-GM and BFU-E for cells removed at different temperatures during secondary drying; however, there were no significant differences in the number of CFU-GEMM. To determine storage stability of lyophilized HPC, cells were stored for 4 weeks at 25 degrees C in the dark. Cells reconstituted immediately after lyophilization produced 580+/-90 CFU-GM ( approximately 40%, relative to unprocessed controls p<0.0001), 170+/-70 BFU-E (approximately 40%, p<0.0001), and 41+/-22 CFU-GEMM (approximately 82%, p = 0.4171), and cells reconstituted after 28 days at room temperature produced 513+/-170 CFU-GM (approximately 35%, relative to unprocessed controls, p<0.0001), 112+/-68 BFU-E (approximately 26%, p<0.0001), and 36+/-17 CFU-GEMM ( approximately 82%, p = 0.2164) These studies are the first to document high level retention of CFU-GEMM following lyophilization and storage for 4 weeks at 25 degrees C. This type of flexible storage stability would potentially permit the ability to ship and store HPC without the need for refrigeration.

In vitro assessment of induced phrenic nerve cryothermal injury.

PubMed

Goff, Ryan P; Bersie, Stephanie M; Iaizzo, Paul A

2014-10-01

Phrenic nerve injury, both left and right, is considered a significant complication of cryoballoon ablation for treatment of drug-refractory atrial fibrillation, and functional recovery of the phrenic nerve can take anywhere from hours to months. The purpose of this study was to focus on short periods of cooling to determine the minimal amount of cooling that may terminate nerve function related to cryo ablation. Left and/or right phrenic nerves were dissected from the pericardium and connective tissue of swine (n = 35 preparations). Nerves were placed in a recording chamber modified with a thermocouple array. This apparatus was placed in a digital water bath to maintain an internal chamber temperature of 37°C. Nerves were stimulated proximally with a 1-V, 0.1-ms square wave. Bipolar compound action potentials were recorded proximal and distal to the site of ablation both before and after ablation, then analyzed to determine changes in latency, amplitude, and duration. Temperatures were recorded at a rate of 5 Hz, and maximum cooling rates were calculated. Phrenic nerves were found to elicit compound action potentials upon stimulation for periods up to 4 hours minimum. Average conduction velocity was 56.7 ± 14.7 m/s preablation and 49.8 ± 16.6 m/s postablation (P = .17). Cooling to mild subzero temperatures ceased production of action potentials for >1 hour. Taking into account the data presented here, previous publications, and a conservative stance, during cryotherapy applications, cooling of the nerve to below 4°C should be avoided whenever possible. Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Winter severity and phenology of spring emergence from the nest in freshwater turtles.

PubMed

Baker, Patrick Joseph; Iverson, John B; Lee, Richard E; Costanzo, Jon P

2010-07-01

Although many species of freshwater turtles emigrate to water soon after hatching, the offspring of some species overwinter on land and move to aquatic habitats in the following spring. Timing of emigration can affect the hatchlings' fitness, but the factors underlying phenology of nest emergence are incompletely understood. We tested the supposition that cold stress imposed during hibernation can influence the timing of nest emergence in three species of turtles in the central USA. In each year of the 6-year study, Chrysemys picta emerged in late March and early April and, on average, these hatchlings left their nests 2 weeks earlier than those of Graptemys geographica and 4 weeks earlier than those of Trachemys scripta. Emergence of conspecific hatchlings from different nests usually occurred over 3-7 weeks, but in some years lasted several additional weeks. Relatively few nests had siblings that emerged on the same day (i.e., synchronously); complete emergence of the typical sibling group required 1 to 2 weeks. In winter, subzero cold occurred with regularity in the nests of all species, though C. picta experienced the lowest temperatures owing to their shallower nests. However, for no species did emergence date or length of the emergence period correlate with winter minimum temperature and, at the level of the individual nest, neither did emergence synchrony or duration. Despite encountering lower temperatures, hatchlings of C. picta emigrated from their nests before those of sympatric species, suggesting that the fitness benefits of early emergence may lead to the improvement of cold-hardiness adaptations in northern populations of turtles.

Cold tolerance of the Australian spur-throated locust, Austracris guttulosa.

PubMed

Woodman, James D

2012-03-01

The cold tolerance of overwintering adult Spur-throated locusts, Austracris guttulosa, was examined using measures of supercooling point relative to gender, environmental acclimation and feeding state as well as mortality for a range of sub-zero temperature exposure treatments. Freezing was lethal and supercooling points ranged from -6 to -12.8°C, but were statistically independent of fresh mass, body water content, acclimation, and/or gut content in fed and starved individuals. A significant interaction effect of gender and feeding status showed that the larger bodied females had decreased supercooling capacity with increased food material in the digestive tract. Post-freezing dissections revealed differences in the amount of freshly consumed and retained food material in the digestive tract between fed and starved individuals of each gender, which could explain this effect based on inoculation of ice crystallisation by food particles. Above supercooling temperatures, neither gender nor the rate of cooling had a significant effect on mortality. When cooled from 25°C at 0.1 or 0.5°Cmin(-1) to a range of experimental minimum temperatures held for 3h, survival was ~74% to -7°C, but declined sharply to ~37% when cooled to -8°C or lower. Although the laboratory experiments reported here suggest that A. guttulosa is not freeze tolerant and unable to rapidly cold harden, exposure to typical cold and frosty nights that very rarely reach below -8°C as a night minimum in the field would be unlikely to cause mortality in the vast majority of overwintering aggregations. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Effect of glycosylation on hydration behavior at the ice-binding surface of the Ocean Pout type III antifreeze protein: a molecular dynamics simulation.

PubMed

Halder, Swagata; Mukhopadhyay, Chaitali

2017-12-01

Antifreeze proteins (AFPs), found in certain vertebrates, plants, fungi and bacteria have the ability to permit their survival in subzero environments by thermal hysteresis mechanism. However, the exact mechanism of ice growth inhibition is still not clearly understood. Here, four long explicit molecular dynamics (MD) simulations have been carried out at two different temperatures (277 and 298 K) with and without glycan to study the conformational rigidity of the Ocean pout type III antifreeze protein in aqueous medium and the structural arrangements of water molecules hydrating its ice-binding surface. It is found that irrespective of the temperature the ice-binding surface (IBS) of the protein is relatively more rigid than its non ice-binding surface (NonIBS) in its native and glycosylated form. Hydrophilic residues N14, T18 and Q44 are essential to antifreeze activity. Radial distribution, density distribution function and nearest neighbor orientation plots with respect to individual two surfaces confirm that density of water molecule near these binding surface in native and glycosylated form are relatively more than the nonbinding surface. The glycosylated form shows a strong peak than the native one. From rotational auto correlation function of water molecules around ice-binding sites, it is prominent that with increase in temperature, strong interaction between the water oxygen and the hydrogen bond acceptor group on the protein-binding surface decreases. This provides a possible molecular reason behind the ice-binding activity of ocean pout at the prism plane of ice.

Winter severity and phenology of spring emergence from the nest in freshwater turtles

NASA Astrophysics Data System (ADS)

Baker, Patrick Joseph; Iverson, John B.; Lee, Richard E.; Costanzo, Jon P.

2010-07-01

Although many species of freshwater turtles emigrate to water soon after hatching, the offspring of some species overwinter on land and move to aquatic habitats in the following spring. Timing of emigration can affect the hatchlings’ fitness, but the factors underlying phenology of nest emergence are incompletely understood. We tested the supposition that cold stress imposed during hibernation can influence the timing of nest emergence in three species of turtles in the central USA. In each year of the 6-year study, Chrysemys picta emerged in late March and early April and, on average, these hatchlings left their nests 2 weeks earlier than those of Graptemys geographica and 4 weeks earlier than those of Trachemys scripta. Emergence of conspecific hatchlings from different nests usually occurred over 3-7 weeks, but in some years lasted several additional weeks. Relatively few nests had siblings that emerged on the same day (i.e., synchronously); complete emergence of the typical sibling group required 1 to 2 weeks. In winter, subzero cold occurred with regularity in the nests of all species, though C. picta experienced the lowest temperatures owing to their shallower nests. However, for no species did emergence date or length of the emergence period correlate with winter minimum temperature and, at the level of the individual nest, neither did emergence synchrony or duration. Despite encountering lower temperatures, hatchlings of C. picta emigrated from their nests before those of sympatric species, suggesting that the fitness benefits of early emergence may lead to the improvement of cold-hardiness adaptations in northern populations of turtles.

Preservation of rat hearts in subfreezing temperature isochoric conditions to - 8 °C and 78 MPa.

PubMed

Wan, Lili; Powell-Palm, Matthew J; Lee, Charles; Gupta, Anshal; Weegman, Bradley P; Clemens, Mark G; Rubinsky, Boris

2018-02-12

Isochoric (constant volume) preservation at subfreezing temperatures is being investigated as a novel method for preserving cells and organs. This study is a first initial effort to evaluate the efficacy of this method for heart preservation, and to provide a preliminary outline of appropriate preservation parameters. To establish a baseline for further studies, rat hearts were preserved in a University of Wisconsin (UW) intracellular solution for one hour under isochoric conditions at: 0 °C (atmospheric pressure - 0.1 MPa), - 4 °C (41 MPa), - 6 °C (60 MPa) and - 8 °C (78 MPa). The viability of the heart was evaluated using Langendorff perfusion and histological examination. The physiological performance of hearts preserved at - 4 °C (41 MPa) was comparable to that of a heart preserved on ice at atmospheric pressure, with no statistically significant difference in histological injury score. However, hearts preserved at -4 °C displayed substantially reduced interstitial edema compared to hearts preserved by conventional hypothermic preservation in UW on ice at atmospheric pressure, suggesting significant protection from increased vascular permeability following preservation. Hearts preserved at - 6 °C (60 MPa) suffered injury from cellular swelling and extensive edema, and at - 8 °C (78 MPa) hearts experienced significant morphological disruption. To the best of our knowledge, this is the first publication showing that a mammalian organ can survive low subfreezing temperatures without the use of a cryoprotective additive. Lowering the preservation temperature reduces metabolism and improves preservation quality, and these results suggest that improvements in preservation are possible at subzero temperatures with low to moderate pressures observed at -4 °C. Notably, tissue damage was observed at lower temperatures (-6 °C or below) accompanying further elevation of pressure associated with isochoric preservation that may prove detrimental. Therefore, subfreezing temperature isochoric preservation protocols should optimize, a combination of temperature and pressure that will minimize the negative effects of elevated pressure while retaining the beneficial effect of lower temperatures and reduced metabolism. Copyright © 2018. Published by Elsevier Inc.

Supercooling ability in two populations of the land snail Helix pomatia (Gastropoda: Helicidae) and ice-nucleating activity of gut bacteria.

PubMed

Nicolai, Annegret; Vernon, Philippe; Lee, Marcia; Ansart, Armelle; Charrier, Maryvonne

2005-02-01

The land snail Helix pomatia (Gastropoda: Helicidae) is widely distributed in Northern and Central Europe where it may experience subzero temperatures during winter months. Its supercooling ability was studied in two populations of H. pomatia. One population originated from Southern Sweden (Gotaland) and the other from Central France (Auvergne). In the experimental design, they were acclimated, over 2 weeks, to artificial winter conditions (hibernation, T=5 degrees C). The Swedish snails showed a rather limited supercooling ability (temperature of crystallization, T(c)=-6.4+/-0.8 degrees C), significantly greater, however, than the supercooling capacity of the population from France (T(c)=-4.6+/-1.4 degrees C). In artificial spring conditions (3 months of hibernation followed by a progressive acclimation, over 2 weeks, to activity at T=20 degrees C), both populations exhibited a similar high T(c) (-2.0+/-1.0 degrees C). The lower T(c) of hibernating Swedish snails could be due to a greater loss of body water, accompanied by a higher concentration of solutes in the hemolymph. In both populations, the variation in hemolymph osmolality measured between hibernating (250-270 mOsm kg(-1)) and active (165-215 mOsm kg(-1)) snails may be explained by the variation in body water mass and did not suggest the production of colligative cryoprotectants. Moreover, the three bacterial strains, Buttiauxella sp., Kluyvera sp., and Tatumella sp. (Enterobacteriaceae) which were isolated from fed snails, but absent in starved snails, did not show any ice-nucleating activity at temperatures higher than -9 degrees C. Only the strain Kluyvera sp. initiated nucleation at -9 degrees C. This strain, therefore, is a weak, also termed a Type III or Class C ice-nucleating active bacterium, but with no influence on the supercooling ability of individual snails. In summary, fluctuations in body water mass of hibernating snail populations, triggering changes in osmolyte concentration, rather than the presence of endogenous ice-nucleating-active bacteria, accounts for fluctuations in their T(c).

Hibernation in an antarctic fish: on ice for winter.

PubMed

Campbell, Hamish A; Fraser, Keiron P P; Bishop, Charles M; Peck, Lloyd S; Egginton, Stuart

2008-03-05

Active metabolic suppression in anticipation of winter conditions has been demonstrated in species of mammals, birds, reptiles and amphibians, but not fish. This is because the reduction in metabolic rate in fish is directly proportional to the decrease in water temperature and they appear to be incapable of further suppressing their metabolic rate independently of temperature. However, the Antarctic fish (Notothenia coriiceps) is unusual because it undergoes winter metabolic suppression irrespective of water temperature. We assessed the seasonal ecological strategy by monitoring swimming activity, growth, feeding and heart rate (f(H)) in N. coriiceps as they free-ranged within sub-zero waters. The metabolic rate of wild fish was extrapolated from f(H )recordings, from oxygen consumption calibrations established in the laboratory prior to fish release. Throughout the summer months N. coriiceps spent a considerable proportion of its time foraging, resulting in a growth rate (G(w)) of 0.18 +/- 0.2% day(-1). In contrast, during winter much of the time was spent sedentary within a refuge and fish showed a net loss in G(w) (-0.05 +/- 0.05% day(-1)). Whilst inactive during winter, N. coriiceps displayed a very low f(H), reduced sensory and motor capabilities, and standard metabolic rate was one third lower than in summer. In a similar manner to other hibernating species, dormancy was interrupted with periodic arousals. These arousals, which lasted a few hours, occurred every 4-12 days. During arousal activity, f(H) and metabolism increased to summer levels. This endogenous suppression and activation of metabolic processes, independent of body temperature, demonstrates that N. coriiceps were effectively 'putting themselves on ice' during winter months until food resources improved. This study demonstrates that at least some fish species can enter a dormant state similar to hibernation that is not temperature driven and presumably provides seasonal energetic benefits.

Thermal experiments with the Asian bush mosquito (Aedes japonicus japonicus) (Diptera: Culicidae) and implications for its distribution in Germany.

PubMed

Reuss, Friederike; Wieser, Andreas; Niamir, Aidin; Bálint, Miklós; Kuch, Ulrich; Pfenninger, Markus; Müller, Ruth

2018-02-05

As ectothermic animals, temperature influences insects in almost every aspect. The potential disease spreading Asian bush mosquito (Aedes japonicus japonicus) is native to temperate East Asia but invasive in several parts of the world. We report on the previously poorly understood temperature-dependence of its life history under laboratory conditions to understand invasion processes and to model temperature niches. To evaluate winter survival, eggs were exposed between 1 day and 14 days to low temperatures (5 °C, 0 °C, -5 °C and -9 °C). Hatching success was drastically decreased after exposure to 0 °C and -5 °C, and the minimal hatching success of 0% was reached at -9 °C after two days. We then exposed larvae to 14 temperatures and assessed their life trait parameters. Larval survival to adulthood was only possible between 10 °C and 31 °C. Based on this, we modelled the optimal (25 °C), minimal (7 °C) and maximal (31 °C) temperature for cumulative female survival. The time to adult emergence ranges from 12 days to 58 days depending on temperature. We used an age-at-emergence-temperature model to calculate the number of potential generations per year for the Asian bush mosquito in Germany with an average of 4.72 potential generations. At lower temperatures, individuals grew larger than at higher temperatures with female R1 length ranging from 3.04 ± 0.1 mm at 31 °C to 4.26 ± 0.2 mm at 15 °C. Reduced egg hatch after exposure to sub-zero temperatures prohibits the establishment of the Asian bush mosquito in large parts of Germany. Larval overwintering is not possible at temperature ≤ 5 °C. The many potential generations displayed per year may contribute to the species' invasion success. This study on the thermal ecology of the Asian bush mosquito adds to our knowledge on the temperature dependence of the species and data could be incorporated in epidemiological and population dynamic modelling.

Non-Toxic, Low-Freezing, Drop-In Replacement Heat Transfer Fluids

NASA Technical Reports Server (NTRS)

Cutbirth, J. Michael

2012-01-01

A non-toxic, non-flammable, low-freezing heat transfer fluid is being developed for drop-in replacement within current and future heat transfer loops currently using water or alcohol-based coolants. Numerous water-soluble compounds were down-selected and screened for toxicological, physical, chemical, compatibility, thermodynamic, and heat transfer properties. Two fluids were developed, one with a freezing point near 0 C, and one with a suppressed freezing point. Both fluids contain an additive package to improve material compatibility and microbial resistance. The optimized sub-zero solution had a freezing point of 30 C, and a freezing volume expansion of 10-percent of water. The toxicity of the solutions was experimentally determined as LD(50) greater than 5g/kg. The solutions were found to produce minimal corrosion with materials identified by NASA as potentially existing in secondary cooling loops. Thermal/hydrodynamic performance exceeded that of glycol-based fluids with comparable freezing points for temperatures Tf greater than 20 C. The additive package was demonstrated as a buffering agent to compensate for CO2 absorption, and to prevent microbial growth. The optimized solutions were determined to have physically/chemically stable shelf lives for freeze/thaw cycles and longterm test loop tests.

Effect of slurry ice on the functional properties of proteins related to quality loss during skipjack tuna (Katsuwonus pelamis) chilled storage.

PubMed

Zhang, Bin; Deng, Shang-gui; Gao, Meng; Chen, Jing

2015-04-01

The effect of slurry ice on the quality of Skipjack tuna (Katsuwonus pelamis) during chilling storage was investigated and compared to flake ice. Slurry ice-treated samples showed significantly higher springiness and chewiness variables than the blank and flake ice-treated samples (P < 0.05). The growth of microorganisms in tuna muscle treated with slurry ice was also down significantly (P < 0.05), and the total aerobic counts didn't reach higher scores than 5.0 log CFU/g during the whole chilling storage. Additionally, the myofibrillar protein, Ca(2+)-ATPase activity, and total sulfydryl (SH) content in muscle treated with slurry ice were all significantly higher than the blank and flake-iced samples (P < 0.05). This was probably due to the faster cooling, subzero final-temperature, and larger heat exchange derived from slurry ice. Standard error of mean and sodium dodecyl sulfate-polyacrylamide gel electrophoresis results also confirmed that slurry ice treatment could effectively retard the degradation of myofibrillar proteins and showed a positive effect on the stability of tissue structures. © 2015 Institute of Food Technologists®

In situ expression of eukaryotic ice-binding proteins in microbial communities of Arctic and Antarctic sea ice.

PubMed

Uhlig, Christiane; Kilpert, Fabian; Frickenhaus, Stephan; Kegel, Jessica U; Krell, Andreas; Mock, Thomas; Valentin, Klaus; Beszteri, Bánk

2015-11-01

Ice-binding proteins (IBPs) have been isolated from various sea-ice organisms. Their characterisation points to a crucial role in protecting the organisms in sub-zero environments. However, their in situ abundance and diversity in natural sea-ice microbial communities is largely unknown. In this study, we analysed the expression and phylogenetic diversity of eukaryotic IBP transcripts from microbial communities of Arctic and Antarctic sea ice. IBP transcripts were found in abundances similar to those of proteins involved in core cellular processes such as photosynthesis. Eighty-nine percent of the IBP transcripts grouped with known IBP sequences from diatoms, haptophytes and crustaceans, but the majority represented novel sequences not previously characterized in cultured organisms. The observed high eukaryotic IBP expression in natural eukaryotic sea ice communities underlines the essential role of IBPs for survival of many microorganisms in communities living under the extreme conditions of polar sea ice.

Eddy Covariance Measurements of Methane Flux Using an Open-Path Gas Analyzer

NASA Astrophysics Data System (ADS)

Burba, G.; Anderson, T.; Zona, D.; Schedlbauer, J.; Anderson, D.; Eckles, R.; Hastings, S.; Ikawa, H.; McDermitt, D.; Oberbauer, S.; Oechel, W.; Riensche, B.; Starr, G.; Sturtevant, C.; Xu, L.

2008-12-01

Methane is an important greenhouse gas with a warming potential of about 23 times that of carbon dioxide over a 100-year cycle (Houghton et al., 2001). Measurements of methane fluxes from the terrestrial biosphere have mostly been made using flux chambers, which have many advantages, but are discrete in time and space and may disturb surface integrity and air pressure. Open-path analyzers offer a number of advantages for measuring methane fluxes, including undisturbed in- situ flux measurements, spatial integration using the Eddy Covariance approach, zero frequency response errors due to tube attenuation, confident water and thermal density terms from co-located fast measurements of water and sonic temperature, and remote deployment due to lower power demands in the absence of a pump. The prototype open-path methane analyzer is a VCSEL (vertical-cavity surface-emitting laser)-based instrument. It employs an open Herriott cell and measures levels of methane with RMS noise below 6 ppb at 10 Hz sampling in controlled laboratory environment. Field maintenance is minimized by a self-cleaning mechanism to keep the lower mirror free of contamination. Eddy Covariance measurements of methane flux using the prototype open-path methane analyzer are presented for the period between 2006 and 2008 in three ecosystems with contrasting weather and moisture conditions: (1) Fluxes over a short-hydroperiod sawgrass wetland in the Florida Everglades were measured in a warm and humid environment with temperatures often exceeding 25oC, variable winds, and frequent heavy dew at night; (2) Fluxes over coastal wetlands in an Arctic tundra were measured in an environment with frequent sub-zero temperatures, moderate winds, and ocean mist; (3) Fluxes over pacific mangroves in Mexico were measured in an environment with moderate air temperatures high winds, and sea spray. Presented eddy covariance flux data were collected from a co-located prototype open-path methane analyzer, LI-7500, and sonic anemometer at a 10 Hz rate. Data were processed using EdiRe software following standard FluxNet methodology, including stationarity tests, frequency response, and Webb- Pearman-Leuning density terms. Further details are provided in the extended conference paper at: ftp://ftp.licor.com/public/GBurba/AGU LI- 7700 Paper-2008.pdf

Microscopic observation of intracellular ice formation in unfertilized mouse ova as a function of cooling rate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leibo, S.P.; McGrath, J.J.; Cravalho, E.G.

A physical-chemical analysis of water loss from cells at subzero temperatures has shown that the likelihood of intracellular ice formation increased with increasing cooling rate. We have now used a modified version of a unique conduction-cooled cryomicroscope stage to observe the freezing of unfertilized mouse ova suspended in dimethyl sulfoxide. Survival measurements showed that the respective survivals of ova were about 65, 56, and 0% when they were cooled at rates of 0.2 to 1.5, 2.5, and 5.4/sup 0/C/min. Direct microscopic observation of mouse ova during freezing showed that the respective fractions of cells that foze intracellularly were 13, 72,more » and 100% when they were cooled at rates of 1.3, 2.9, and 4.8/sup 0/C/min or faster. These values agree with those predicted from the physical-chemical analysis for cells the size of mouse ova. The microscopic observations have also shown that intracellular freezing generally occurred at about -40 to -45/sup 0/C. We had previously observed that mouse embryos must be cooled slowly to -50/sup 0/C or below if they are to survive subsequent rapid cooling to -196/sup 0/C. The observation of intracellular ice formation at -45/sup 0/C supports the interpretation that at temperatures above -50/sup 0/C the embryos still contain water capable of freezing intracellulary.« less

Seventy-five years of masting and rodent population peaks in Norway: Why do wood mice not follow the rules?

PubMed

Selås, Vidar

2016-09-01

Wood mouse (Apodemus sylvaticus) populations are expected to show a peak in autumn in the year after a mast year of sessile oak (Quercus petraea), because stored acorns increase winter survival. In Aust-Agder, South Norway, only 16 of 34 mast years from 1939-2014 were followed by a year with a peak in the wood mouse population. For many of the remaining instances, there rather was a minor peak 2 or 3 years after the mast. In multiple logistic regression models, the probability of a wood mouse population peak after a mast year of sessile oak was positively related to a snow-corrected temperature index of the previous winter and negatively to a small rodent population index of the previous autumn. The present study thus supports the hypothesis that longer periods with snow-free ground and subzero temperatures negatively affect wood mouse winter survival. Because it may be difficult for wood mice to survive on a diet consisting of acorns alone, the negative relationship with the rodent population index of the previous year is most likely caused by an over-exploitation of necessary alternative food resources, such as other plant seeds and arthropods. Stored acorns not utilized during one winter are assumed to benefit wood mice in a succeeding winter, giving a delayed population peak relative to the mast year. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

Comparative higher-order structure analysis of antibody biosimilars using combined bottom-up and top-down hydrogen-deuterium exchange mass spectrometry.

PubMed

Pan, Jingxi; Zhang, Suping; Borchers, Christoph H

2016-12-01

Hydrogen/deuterium exchange (HDX) coupled with mass spectrometry (MS) is a powerful technique for higher-order structural characterization of antibodies. Although the peptide-based bottom-up HDX approach and the protein-based top-down HDX approach have complementary advantages, the work done so far on biosimilars has involved only one or the other approach. Herein we have characterized the structures of two bevacizumab (BEV) biosimilars and compared them to the reference BEV using both methods. A sequence coverage of 87% was obtained for the heavy chain and 74% for the light chain in the bottom-up approach. The deuterium incorporation behavior of the peptic peptides from the three BEVs were compared side by side and showed no differences at various HDX time points. Top-down experiments were carried out using subzero temperature LC-MS, and the deuterium incorporation of the intact light chain and heavy chain were obtained. Top-down ETD was also performed to obtain amino acid-level HDX information that covered 100% of the light chain, but only 50% coverage is possible for the heavy chain. Consistent with the intact subunit level data, no differences were observed in the amino acid level HDX data. All these results indicate that there are no differences between the three BEV samples with respect to their high-order structures. The peptide level information from the bottom-up approach, and the residue level and intact subunit level information from the top-down approach were complementary and covered the entire antibody. Copyright © 2016 Elsevier B.V. All rights reserved.

Ice-binding proteins confer freezing tolerance in transgenic Arabidopsis thaliana.

PubMed

Bredow, Melissa; Vanderbeld, Barbara; Walker, Virginia K

2017-01-01

Lolium perenne is a freeze-tolerant perennial ryegrass capable of withstanding temperatures below -13 °C. Ice-binding proteins (IBPs) presumably help prevent damage associated with freezing by restricting the growth of ice crystals in the apoplast. We have investigated the expression, localization and in planta freezing protection capabilities of two L. perenne IBP isoforms, LpIRI2 and LpIRI3, as well as a processed IBP (LpAFP). One of these isoforms, LpIRI2, lacks a conventional signal peptide and was assumed to be a pseudogene. Nevertheless, both LpIRI2 and LpIRI3 transcripts were up-regulated following cold acclimation. LpIRI2 also demonstrated ice-binding activity when produced recombinantly in Escherichia coli. Both the LpIRI3 and LpIRI2 isoforms appeared to accumulate in the apoplast of transgenic Arabidopsis thaliana plants. In contrast, the fully processed isoform, LpAFP, remained intracellular. Transgenic plants expressing either LpIRI2 or LpIRI3 showed reduced ion leakage (12%-39%) after low-temperature treatments, and significantly improved freezing survival, while transgenic LpAFP-expressing lines did not confer substantial subzero protection. Freeze protection was further enhanced by with the introduction of more than one IBP isoform; ion leakage was reduced 26%-35% and 10% of plants survived temperatures as low as -8 °C. Our results demonstrate that apoplastic expression of multiple L. perenne IBP isoforms shows promise for providing protection to crops susceptible to freeze-induced damage. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Seepage phenomena on Mars at subzero temperature

NASA Astrophysics Data System (ADS)

Kereszturi, Akos; Möhlmann, Diedrich; Berczi, Szaniszlo; Ganti, Tibor; Horvath, Andras; Kuti, Adrienn; Pocs, Tamas; Sik, Andras; Szathmary, Eors

At the southern hemisphere of Mars seasonal slope structures emanating from Dark Dune Spots are visible on MGS MOC, and MRO HiRISE images. Based on their analysis two groups of streaks could be identified: diffuse and fan shaped ones forming in an earlier phase of local spring, probably by CO2 gas jets, and confined streaks forming only on steep slopes during a later seasonal phase. The dark color of the streaks may arise from the dark color of the dune grains where surface frost disappeared above them, or caused by the phase change of the water ice to liquid-like water, or even it may be influenced by the solutes of salts in the undercooled interfacial water The second group's morphology (meandering style, ponds at their end), morphometry, and related theoretical modelling suggest they may form by undercooled water that remains in liquid phase in a thin layer around solid grains. We analyzed sequence of images, temperature and topographic data of Russel (54S 12E), Richardson (72S 180E) and an unnamed crater (68S 2E) during southern spring. The dark streaks here show slow motion, with an average speed of meter/day, when the maximal daytime temperature is between 190 and 220 K. Based on thermophysical considerations a thin layer of interfacial water is inevitable on mineral surfaces under the present conditions of Mars. With 10 precipitable micrometer of atmospheric water vapor, liquid phase can be present down about 190 K. Under such conditions dark streaks may form by the movement of grains lubricatred by interfacial water. This possibility have various consequences on chemical, mechanical or even possible astrobiological processes on Mars. Acknowledgment: This work was supported by the ESA ECS-project No. 98004 and the Pro Renovanda Cultura Hungariae Foundation.

Antifreeze Proteins Modify the Freezing Process In Planta12

PubMed Central

Griffith, Marilyn; Lumb, Chelsey; Wiseman, Steven B.; Wisniewski, Michael; Johnson, Robert W.; Marangoni, Alejandro G.

2005-01-01

During cold acclimation, winter rye (Secale cereale L. cv Musketeer) plants accumulate antifreeze proteins (AFPs) in the apoplast of leaves and crowns. The goal of this study was to determine whether these AFPs influence survival at subzero temperatures by modifying the freezing process or by acting as cryoprotectants. In order to inhibit the growth of ice, AFPs must be mobile so that they can bind to specific sites on the ice crystal lattice. Guttate obtained from cold-acclimated winter rye leaves exhibited antifreeze activity, indicating that the AFPs are free in solution. Infrared video thermography was used to observe freezing in winter rye leaves. In the absence of an ice nucleator, AFPs had no effect on the supercooling temperature of the leaves. However, in the presence of an ice nucleator, AFPs lowered the temperature at which the leaves froze by 0.3°C to 1.2°C. In vitro studies showed that apoplastic proteins extracted from cold-acclimated winter rye leaves inhibited the recrystallization of ice and also slowed the rate of migration of ice through solution-saturated filter paper. When we examined the possible role of winter rye AFPs in cryoprotection, we found that lactate dehydrogenase activity was higher after freezing in the presence of AFPs compared with buffer, but the same effect was obtained by adding bovine serum albumin. AFPs had no effect on unstacked thylakoid volume after freezing, but did inhibit stacking of the thylakoids, thus indicating a loss of thylakoid function. We conclude that rye AFPs have no specific cryoprotective activity; rather, they interact directly with ice in planta and reduce freezing injury by slowing the growth and recrystallization of ice. PMID:15805474

NASA Snaps Picture of Eastern U.S. in a Record-Breaking "Freezer"

NASA Image and Video Library

2015-02-20

NASA's Terra satellite captured an image of the snow-covered eastern U.S. that looks like the states have been sitting in a freezer. In addition to the snow cover, Arctic and Siberian air masses have settled in over the Eastern U.S. triggering many record low temperatures in many states. On Feb. 19 at 16:40 UTC (11:40 a.m. EST), the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument that flies aboard NASA's Terra satellite captured a picture of the snowy landscape. The snow cover combined with the frosty air mass made the eastern U.S. feel like the inside of freezer. The MODIS image was created at NASA's Goddard Space Flight Center in Greenbelt, Maryland. On the morning of Feb. 20, NOAA's Weather Prediction Center (WPC) noted, "There were widespread subzero overnight lows Thursday night (Feb. 19) extending from Illinois to western Virginia, and numerous record lows were set. Bitterly-cold arctic air is setting numerous temperature records across the eastern U.S. and will keep temperatures well below normal on Friday (Feb. 20)." In Baltimore, Maryland, a low temperature of 1F broke the record low for coldest morning recorded at the Thurgood Marshall Baltimore Washington-International Airport. In Louisville, Kentucky, temperatures dropped to -6F, breaking the old record low of 0F, according to meteorologist Brian Goode of WAVE-TV. Meanwhile, Richmond Kentucky bottomed out at a frigid -32F. In North Carolina, a record low temperature was set at Charlotte where the overnight temperature bottomed out at 7F breaking the old record of 13F in 1896. In Asheville, temperatures dropped to just 4F breaking the old record of 10F in 1979. Temperature records for Asheville extend back to 1876. Several records were also broken in Georgia, according to Matt Daniel, a meteorologist at WMAZ-TV, Macon Georgia, who cited data from the National Weather Service. Daniel said that Macon set a new record low when the temperature dropped to 18F, beating the previous record of 21F set in 1958. Athens broke a new record low, too dropping to 14F and beating the old record of 18F set in 1958/1928. NOAA's NPC noted that "Highs on Friday (Feb. 20) will struggle to get out of the teens from the Ohio Valley to the Mid-Atlantic region. After Friday, temperatures are forecast to moderate and get closer to February averages as a storm system approaches from the west." Image Credit: NASA Goddard MODIS Rapid Response Team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Teleost fish models in membrane transport research: the PEPT1(SLC15A1) H+–oligopeptide transporter as a case study

PubMed Central

Romano, Alessandro; Barca, Amilcare; Storelli, Carlo; Verri, Tiziano

2014-01-01

Human genes for passive, ion-coupled transporters and exchangers are included in the so-called solute carrier (SLC) gene series, to date consisting of 52 families and 398 genes. Teleost fish genes for SLC proteins have also been described in the last two decades, and catalogued in preliminary SLC-like form in 50 families and at least 338 genes after systematic GenBank database mining (December 2010–March 2011). When the kinetic properties of the expressed proteins are studied in detail, teleost fish SLC transporters always reveal extraordinary ‘molecular diversity’ with respect to the mammalian counterparts, which reflects peculiar adaptation of the protein to the physiology of the species and/or to the environment where the species lives. In the case of the H+–oligopeptide transporter PEPT1(SLC15A1), comparative analysis of diverse teleost fish orthologs has shown that the protein may exhibit very eccentric properties in terms of pH dependence (e.g. the adaptation of zebrafish PEPT1 to alkaline pH), temperature dependence (e.g. the adaptation of icefish PEPT1 to sub-zero temperatures) and/or substrate specificity (e.g. the species-specificity of PEPT1 for the uptake of l-lysine-containing peptides). The revelation of such peculiarities is providing new contributions to the discussion on PEPT1 in both basic (e.g. molecular structure–function analyses) and applied research (e.g. optimizing diets to enhance growth of commercially valuable fish). PMID:23981715

Structural Investigation of the Oligosaccharide Portion Isolated from the Lipooligosaccharide of the Permafrost Psychrophile Psychrobacter arcticus 273-4.

PubMed

Casillo, Angela; Parrilli, Ermenegilda; Filomena, Sannino; Lindner, Buko; Lanzetta, Rosa; Parrilli, Michelangelo; Tutino, Maria Luisa; Corsaro, Maria Michela

2015-07-22

Psychrophilic microorganisms have successfully colonized all permanently cold environments from the deep sea to mountain and polar regions. The ability of an organism to survive and grow in cryoenviroments depends on a number of adaptive strategies aimed at maintaining vital cellular functions at subzero temperatures, which include the structural modifications of the membrane. To understand the role of the membrane in the adaptation, it is necessary to characterize the cell-wall components, such as the lipopolysaccharides, that represent the major constituent of the outer membrane. The aim of this study was to investigate the structure of the carbohydrate backbone of the lipooligosaccharide (LOS) isolated from the cold-adapted Psychrobacter arcticus 273-4. The strain, isolated from a 20,000-to-30,000-year-old continuously frozen permafrost in Siberia, was cultivated at 4 °C. The LOS was isolated from dry cells and analyzed by means of chemical methods. In particular, it was degraded either by mild acid hydrolysis or by hydrazinolysis and investigated in detail by (1)H and (13)C NMR spectroscopy and by ESI FT-ICR mass spectrometry. The oligosaccharide was characterized by the substitution of the heptose residue, usually linked to Kdo in the inner core, with a glucose, and for the unusual presence of N-acetylmuramic acid.

Structure and Dynamics of Antifreeze Protein--Model Membrane Interactions: A Combined Spectroscopic and Molecular Dynamics Study.

PubMed

Kar, Rajiv K; Mroue, Kamal H; Kumar, Dinesh; Tejo, Bimo A; Bhunia, Anirban

2016-02-11

Antifreeze proteins (AFPs) are the key biomolecules that enable species to survive under subzero temperature conditions. The physiologically relevant activities of AFPs are based on the adsorption to ice crystals, followed by the inhibition of subsequent crystal layer growth of ice, routed with depression in freezing point in a noncolligative manner. The functional attributes governing the mechanism by which AFPs inhibit freezing of body fluids in bacteria, fungi, plants, and fishes are mainly attributed to their adsorption onto the surface of ice within the physiological system. Importantly, AFPs are also known for their application in cryopreservation of biological samples that might be related to membrane interaction. To date, there is a paucity of information detailing the interaction of AFPs with membrane structures. Here, we focus on elucidating the biophysical properties of the interactions between AFPs and micelle models that mimic the membrane system. Micelle model systems of zwitterionic DPC and negatively charged SDS were utilized in this study, against which a significant interaction is experienced by two AFP molecules, namely, Peptide 1m and wfAFP (the popular AFP sourced from winter flounder). Using low- and high-resolution biophysical characterization techniques, such as circular dichroism (CD) and NMR spectroscopy, a strong evidence for the interactions of these AFPs with the membrane models is revealed in detail and is corroborated by in-depth residue-specific information derived from molecular dynamics simulation. Altogether, these results not only strengthen the fact that AFPs interact actively with membrane systems, but also demonstrate that membrane-associated AFPs are dynamic and capable of adopting a number of conformations rendering fluidity to the system.

Widespread surface meltwater drainage in Antarctica

NASA Astrophysics Data System (ADS)

Kingslake, J.; Ely, J.; Das, I.; Bell, R. E.

2016-12-01

Surface meltwater is thought to cause ice-shelf disintegration, which accelerates the contribution of ice sheets to sea-level rise. Antarctic surface melting is predicted to increase and trigger further ice-shelf disintegration during this century. These climate-change impacts could be modulated by an active hydrological network analogous to the one in operation in Greenland. Despite some observations of Antarctic surface and sub-surface hydrological systems, large-scale active surface drainage in Antarctica has rarely been studied. We use satellite imagery and aerial photography to reveal widespread active hydrology on the surface of the Antarctic Ice Sheet as far south as 85o and as high as 1800 m a.s.l., often near mountain peaks that protrude through the ice (nunataks) and relatively low-albedo `blue-ice areas'. Despite predominantly sub-zero regional air temperatures, as simulated by a regional climate model, Antarctic active drainage has persisted for decades, transporting water through surface streams and feeding vast melt ponds up to 80 km long. Drainage networks (the largest are over 100 km in length) form on flat ice shelves, steep outlet glaciers and ice-sheet flanks across the West and East Antarctica Ice Sheets. Motivated by the proximity of many drainage systems to low-albedo rock and blue-ice areas, we hypothesize a positive feedback between exposed-rock extent, BIA formation, melting and ice-sheet thinning. This feedback relies on drainage moving water long distances from areas near exposed rock, across the grounding line onto and across ice shelves - a process we observe, but had previously thought to be unlikely in Antarctica. This work highlights previously-overlooked processes, not captured by current regional-scale models, which may accelerate the retreat of the Antarctic Ice Sheet.

Comparison of forced-air warming systems with upper body blankets using a copper manikin of the human body.

PubMed

Bräuer, A; English, M J M; Steinmetz, N; Lorenz, N; Perl, T; Braun, U; Weyland, W

2002-09-01

Forced-air warming with upper body blankets has gained high acceptance as a measure for the prevention of intraoperative hypothermia. However, data on heat transfer with upper body blankets are not yet available. This study was conducted to determine the heat transfer efficacy of eight complete upper body warming systems and to gain more insight into the principles of forced-air warming. Heat transfer of forced-air warmers can be described as follows: Qdot;=h. DeltaT. A, where Qdot;= heat flux [W], h=heat exchange coefficient [W m-2 degrees C-1], DeltaT=temperature gradient between the blanket and surface [ degrees C], and A=covered area [m2]. We tested eight different forced-air warming systems: (1) Bair Hugger and upper body blanket (Augustine Medical Inc. Eden Prairie, MN); (2) Thermacare and upper body blanket (Gaymar Industries, Orchard Park, NY); (3) Thermacare (Gaymar Industries) with reusable Optisan upper body blanket (Willy Rüsch AG, Kernen, Germany); (4) WarmAir and upper body blanket (Cincinnati Sub-Zero Products, Cincinnati, OH); (5) Warm-Gard and single use upper body blanket (Luis Gibeck AB, Upplands Väsby, Sweden); (6) Warm-Gard and reusable upper body blanket (Luis Gibeck AB); (7) WarmTouch and CareDrape upper body blanket (Mallinckrodt Medical Inc., St. Luis, MO); and (8) WarmTouch and reusable MultiCover trade mark upper body blanket (Mallinckrodt Medical Inc.) on a previously validated copper manikin of the human body. Heat flux and surface temperature were measured with 11 calibrated heat flux transducers. Blanket temperature was measured using 11 thermocouples. The temperature gradient between the blanket and surface (DeltaT) was varied between -8 and +8 degrees C, and h was determined by linear regression analysis as the slope of DeltaT vs. heat flux. Mean DeltaT was determined for surface temperatures between 36 and 38 degrees C, as similar mean skin surface temperatures have been found in volunteers. The covered area was estimated to be 0.35 m2. Total heat flow from the blanket to the manikin was different for surface temperatures between 36 and 38 degrees C. At a surface temperature of 36 degrees C the heat flows were higher (4-26.6 W) than at surface temperatures of 38 degrees C (2.6-18.1 W). The highest total heat flow was delivered by the WarmTouch trade mark system with the CareDrape trade mark upper body blanket (18.1-26.6 W). The lowest total heat flow was delivered by the Warm-Gard system with the single use upper body blanket (2.6-4 W). The heat exchange coefficient varied between 15.1 and 36.2 W m-2 degrees C-1, and mean DeltaT varied between 0.5 and 3.3 degrees C. We found total heat flows of 2.6-26.6 W by forced-air warming systems with upper body blankets. However, the changes in heat balance by forced-air warming systems with upper body blankets are larger, as these systems are not only transferring heat to the body but are also reducing heat losses from the covered area to zero. Converting heat losses of approximately 37.8 W to heat gain, results in a 40.4-64.4 W change in heat balance. The differences between the systems result from different heat exchange coefficients and different mean temperature gradients. However, the combination of a high heat exchange coefficient with a high mean temperature gradient is rare. This fact offers some possibility to improve these systems.

Diversity and physiology of culturable bacteria associated with a coastal Antarctic ice core.

PubMed

Antony, Runa; Krishnan, K P; Laluraj, C M; Thamban, Meloth; Dhakephalkar, P K; Engineer, Anupama S; Shivaji, S

2012-06-20

Microbiological studies of polar ice at different depths may provide important comparisons, as they preserve records of microbial cells and past climate. In this study, we examined bacterial abundance, diversity and glaciochemical composition from three depths of an ice core from coastal Dronning Maud Land, East Antarctica. Higher bacterial abundance corresponded with high in situ sea-salt Na(+) and dust concentration, suggesting that bacteria might have been transported and deposited into ice along with dust particles and marine aerosols. Fourteen bacterial isolates belonging to the genera Methylobacterium, Brevundimonas, Paenibacillus, Bacillus and Micrococcus were retrieved. Frequent isolation of similar bacterial genera from different cold environments suggests that they possess features that enable survival and metabolism for extended periods of time at sub-zero temperatures. The highest number and diversity of recoverable bacteria was obtained from 49 m depth corresponding to 1926 AD and consisted of bacteria from 4 different genera whereas at 11 m (1989 AD) and 33 m (1953 AD) samples only species belonging to the genera Bacillus was recovered. Among the Bacillus species, Bacillus aryabhattai which has been reported only from the upper stratosphere, was isolated and is the first record from the Earth's surface. Methylobacterium was the most dominant genera at 49 m depth and its prevalence is attributable to a combination of high in situ methanesulfonate concentration, specialized metabolism and environmental hardiness of Methylobacterium. Some of the isolated bacteria were found to respire and grow using methanesulfonate, suggesting that they may utilize this substrate to sustain growth in ice. In addition, NO(3)(-) (2.93-3.69 μM), NH(4)(+) (1.45-3.90 μM) and PO(4)(3-) (0.01-0.75 μM) present in the ice could be potential sources fueling bacterial metabolism in this environment. It could be deduced from the study that variation in bacterial abundance and diversity was probably associated with the prevailing in situ conditions in ice. Copyright © 2012 Elsevier GmbH. All rights reserved.

Knockdown of Ice-Binding Proteins in Brachypodium distachyon Demonstrates Their Role in Freeze Protection

PubMed Central

Bredow, Melissa; Vanderbeld, Barbara; Walker, Virginia K.

2016-01-01

Sub-zero temperatures pose a major threat to the survival of cold-climate perennials. Some of these freeze-tolerant plants produce ice-binding proteins (IBPs) that offer frost protection by restricting ice crystal growth and preventing expansion-induced lysis of the plasma membranes. Despite the extensive in vitro characterization of such proteins, the importance of IBPs in the freezing stress response has not been investigated. Using the freeze-tolerant grass and model crop, Brachypodium distachyon, we characterized putative IBPs (BdIRIs) and generated the first ‘IBP-knockdowns’. Seven IBP sequences were identified and expressed in Escherichia coli, with all of the recombinant proteins demonstrating moderate to high levels of ice-recrystallization inhibition (IRI) activity, low levels of thermal hysteresis (TH) activity (0.03−0.09°C at 1 mg/mL) and apparent adsorption to ice primary prism planes. Following plant cold acclimation, IBPs purified from wild-type B. distachyon cell lysates similarly showed high levels of IRI activity, hexagonal ice-shaping, and low levels of TH activity (0.15°C at 0.5 mg/mL total protein). The transfer of a microRNA construct to wild-type plants resulted in the attenuation of IBP activity. The resulting knockdown mutant plants had reduced ability to restrict ice-crystal growth and a 63% reduction in TH activity. Additionally, all transgenic lines were significantly more vulnerable to electrolyte leakage after freezing to −10°C, showing a 13−22% increase in released ions compared to wild-type. IBP-knockdown lines also demonstrated a significant decrease in viability following freezing to −8°C, with some lines showing only two-thirds the survival seen in control lines. These results underscore the vital role IBPs play in the development of a freeze-tolerant phenotype and suggests that expression of these proteins in frost-susceptible plants could be valuable for the production of more winter-hardy crops. PMID:27959937

Knockdown of Ice-Binding Proteins in Brachypodium distachyon Demonstrates Their Role in Freeze Protection.

PubMed

Bredow, Melissa; Vanderbeld, Barbara; Walker, Virginia K

2016-01-01

Sub-zero temperatures pose a major threat to the survival of cold-climate perennials. Some of these freeze-tolerant plants produce ice-binding proteins (IBPs) that offer frost protection by restricting ice crystal growth and preventing expansion-induced lysis of the plasma membranes. Despite the extensive in vitro characterization of such proteins, the importance of IBPs in the freezing stress response has not been investigated. Using the freeze-tolerant grass and model crop, Brachypodium distachyon, we characterized putative IBPs (BdIRIs) and generated the first 'IBP-knockdowns'. Seven IBP sequences were identified and expressed in Escherichia coli, with all of the recombinant proteins demonstrating moderate to high levels of ice-recrystallization inhibition (IRI) activity, low levels of thermal hysteresis (TH) activity (0.03-0.09°C at 1 mg/mL) and apparent adsorption to ice primary prism planes. Following plant cold acclimation, IBPs purified from wild-type B. distachyon cell lysates similarly showed high levels of IRI activity, hexagonal ice-shaping, and low levels of TH activity (0.15°C at 0.5 mg/mL total protein). The transfer of a microRNA construct to wild-type plants resulted in the attenuation of IBP activity. The resulting knockdown mutant plants had reduced ability to restrict ice-crystal growth and a 63% reduction in TH activity. Additionally, all transgenic lines were significantly more vulnerable to electrolyte leakage after freezing to -10°C, showing a 13-22% increase in released ions compared to wild-type. IBP-knockdown lines also demonstrated a significant decrease in viability following freezing to -8°C, with some lines showing only two-thirds the survival seen in control lines. These results underscore the vital role IBPs play in the development of a freeze-tolerant phenotype and suggests that expression of these proteins in frost-susceptible plants could be valuable for the production of more winter-hardy crops.

Aspects of the tribological behaviour of powders recycled from rapid steel treated sub-zero

NASA Astrophysics Data System (ADS)

Radu, S.; Ciobanu, M.

2017-02-01

The recycling of high-alloyed steels represents a significant opportunity in Powder Metallurgy as it permits the use of raw materials with relatively low prices compared to the conventional methods. Recycling can be achieved by two methods: from spraying debris resulted from worn cutting tools and processes obtained from processing chip drilling and re-sharpening of tools. The research aims to confirm that wastes from rapid steels can become, by the successive processing, metal powders that can thereafter be used for cutting tools of lathe type removable plate. After pressing and sintering the recycling powder, cylindrical samples were obtained that were subsequently applied a subcritical annealing. Wear tests conducted on a tribometer type TRB-01-02541 confirmed that their wear resistance is superior to the same samples that were sintered, hardened and tempered in oil. This paper was accepted for publication in Proceedings after double peer reviewing process but was not presented at the Conference ROTRIB’16.

Supercooling Preservation Of The Rat Liver For Transplantation

PubMed Central

Bruinsma, Bote G.; Berendsen, Tim A.; Izamis, Maria-Louisa; Yeh, Heidi; Yarmush, Martin L.; Uygun, Korkut

2015-01-01

The current standard for liver preservation is limited in duration. Employing a novel subzero preservation technique that includes supercooling and machine perfusion can significantly improve preservation and prolong storage times. By loading rat livers with cryoprotectants to prevent both intra- and extracellular ice formation and protect against hypothermic injury, livers can be cooled to −6 °C without freezing and kept viable for up to 96 hours. Here, we describe the procedures of loading cryoprotectants by means of subnormothermic machine perfusion (SNMP), controlled cooling to a supercooled state, followed by SNMP recovery and orthotopic liver transplantation. PMID:25692985

Biogeochemistry and Genetic Potential related to Denitrification of Heterotrophic Bacteria isolated from Lake Vida Cryobrine

NASA Astrophysics Data System (ADS)

Trubl, G.; Kuhn, E.; Ichimura, A.; Fritsen, C. H.; Murray, A. E.

2012-12-01

Lake Vida, one of the largest lakes in McMurdo Dry Valleys, Antarctica, is a thick block of ice permeated by brine channels below 16 m that contain the highest levels of nitrous oxide (N2O) that have been reported from a terrestrial environment (86.6 ± 5.9 μM). The subzero -13.4oC brine (18% salinity) has an unusual geochemistry with high levels of iron, dissolved organic carbon, nitrate, and ammonium. A number of heterotrophic bacteria were cultivated from this unusual, extreme ecosystem that has been isolated for at least three thousand years. The aim of this research was to phylogenetically characterize the bacterial isolates (using 16S ribosomal RNA analysis) and investigate their denitrifying abilities and genetic potential related to key reactions in the denitrification cycle. Fifteen phylotypes were isolated from Lake Vida brine among three phyla: Gammaproteobacteria, Actinobacteria, and Firmicutes. Based on the 16S ribosomal RNA analysis, Marinobacter was the most abundant (56%) genus identified among the 57 isolates. The other isolates were related to the genera Psychrobacter, Exiguobacterium, Kocuria, and Microbacterium. Representatives of each phylotype were characterized and verified for: (1) Nitrate (NO3-) reduction to either N2O or dinitrogen (N2) by Gas Chromatography; (2) presence of the genes nirK or nirS for NO3- reduction and nosZ for nitric oxide (NO) reduction by polymerase chain reaction (PCR); and (3) growth response to salinity and temperature gradients. Thirty five of the Lake Vida isolates produced either N2O or N2 coupled to cell growth. All 57 isolates have grown across a 32°C temperature range (-10°C to 22°C) and 54 isolates were halotolerant bacteria (growing in 0% to 16% salinity), while the last three isolates were halophilic. Electron microscopy revealed membrane vesicles and extracellular polymeric substances (EPS) around the Lake Vida isolates, which may be a survival adaptation. Investigating the denitrification and other biogeochemical cycles of Lake Vida can help us comprehend the origin of the high levels of N2O in the brine, provide insight into the origin of the Lake and the culture collection established from this isolated cryoecosystem will be useful for future physiological and biogeochemical experimentation to explore the limits of life.

Comparison of forced-air warming systems with lower body blankets using a copper manikin of the human body.

PubMed

Bräuer, A; English, M J M; Lorenz, N; Steinmetz, N; Perl, T; Braun, U; Weyland, W

2003-01-01

Forced-air warming has gained high acceptance as a measure for the prevention of intraoperative hypothermia. However, data on heat transfer with lower body blankets are not yet available. This study was conducted to determine the heat transfer efficacy of six complete lower body warming systems. Heat transfer of forced-air warmers can be described as follows:[1]Qdot;=h.DeltaT.A where Qdot; = heat transfer [W], h = heat exchange coefficient [W m-2 degrees C-1], DeltaT = temperature gradient between blanket and surface [ degrees C], A = covered area [m2]. We tested the following forced-air warmers in a previously validated copper manikin of the human body: (1) Bair Hugger and lower body blanket (Augustine Medical Inc., Eden Prairie, MN); (2) Thermacare and lower body blanket (Gaymar Industries, Orchard Park, NY); (3) WarmAir and lower body blanket (Cincinnati Sub-Zero Products, Cincinnati, OH); (4) Warm-Gard(R) and lower body blanket (Luis Gibeck AB, Upplands Väsby, Sweden); (5) Warm-Gard and reusable lower body blanket (Luis Gibeck AB); and (6) WarmTouch and lower body blanket (Mallinckrodt Medical Inc., St. Luis, MO). Heat flux and surface temperature were measured with 16 calibrated heat flux transducers. Blanket temperature was measured using 16 thermocouples. DeltaT was varied between -10 and +10 degrees C and h was determined by a linear regression analysis as the slope of DeltaT vs. heat flux. Mean DeltaT was determined for surface temperatures between 36 and 38 degrees C, because similar mean skin temperatures have been found in volunteers. The area covered by the blankets was estimated to be 0.54 m2. Heat transfer from the blanket to the manikin was different for surface temperatures between 36 degrees C and 38 degrees C. At a surface temperature of 36 degrees C the heat transfer was higher (between 13.4 W to 18.3 W) than at surface temperatures of 38 degrees C (8-11.5 W). The highest heat transfer was delivered by the Thermacare system (8.3-18.3 W), the lowest heat transfer was delivered by the Warm-Gard system with the single use blanket (8-13.4 W). The heat exchange coefficient varied between 12.5 W m-2 degrees C-1 and 30.8 W m-2 degrees C-1, mean DeltaT varied between 1.04 degrees C and 2.48 degrees C for surface temperatures of 36 degrees C and between 0.50 degrees C and 1.63 degrees C for surface temperatures of 38 degrees C. No relevant differences in heat transfer of lower body blankets were found between the different forced-air warming systems tested. Heat transfer was lower than heat transfer by upper body blankets tested in a previous study. However, forced-air warming systems with lower body blankets are still more effective than forced-air warming systems with upper body blankets in the prevention of perioperative hypothermia, because they cover a larger area of the body surface.

Effect of Different Chromium Additions on the Microstructure and Mechanical Properties of Multipass Weld Joint of Duplex Stainless Steel

NASA Astrophysics Data System (ADS)

Kang, Dong Hoon; Lee, Hae Woo

2012-12-01

The correlation between the mechanical properties and ferrite volume fraction (approximately 40, 50, and 60 Ferrite Number [FN]) in duplex stainless steel weld metals were investigated by changing the Cr content in filler wires with a flux-cored arc-welding (FCAW) process. The interpass temperature was thoroughly maintained under a maximum of 423 K (150 °C), and the heat input was also sustained at a level under 15 KJ/cm in order to minimize defects. The microstructure examination demonstrated that the δ-ferrite volume fraction in the deposited metals increased as the Cr/Ni equivalent ratio increased, and consequently, chromium nitride (Cr2N) precipitation was prone to occur in the ferrite domains due to low solubility of nitrogen in this phase. Thus, more dislocations are pinned by the precipitates, thereby lowering the mobility of the dislocations. Not only can this lead to the strength improvement, but also it can accentuate embrittlement of the weld metal at subzero temperature. Additionally, the solid-solution strengthening by an increase of Cr and Mo content in austenite phase depending on the reduction of austenite proportion also made an impact on the increase of the tensile and yield strength. On the other hand, the impact test (at 293 K, 223 K, and 173 K [20 °C, -50 °C, and -100 °C]) showed that the specimen containing about 40 to 50 FN had the best result. The absorbed energy of about 40 to 50 J sufficiently satisfied the requirements for industrial applications at 223 K (-50 °C), while the ductile-to-brittle transition behavior exhibited in weldment containing 60 FN. As the test temperature decreased under 223 K (-50 °C), a narrow and deep dimple was transformed into a wide and shallow dimple, and a significant portion of the fracture surface was occupied by a flat cleavage facet with river patterns.

Mineral solubilities in the Na-K-Mg-Ca-Cl-SO 4-H 2O system: a re-evaluation of the sulfate chemistry in the Spencer-Møller-Weare model

NASA Astrophysics Data System (ADS)

Marion, Giles M.; Farren, Ronald E.

1999-05-01

The Spencer-Møller-Weare (SMW) (1990) model is parameterized for the Na-K-Mg-Ca-Cl-SO 4-H 2O system over the temperature range from -60° to 25°C. This model is one of the few complex chemical equilibrium models for aqueous solutions parameterized for subzero temperatures. The primary focus of the SMW model parameterization and validation deals with chloride systems. There are problems with the sulfate parameterization of the SMW model, most notably with sodium sulfate and magnesium sulfate. The primary objective of this article is to re-estimate the Pitzer-equation parameters governing interactions among sodium, potassium, magnesium, and calcium with sulfate in the SMW model. A mathematical algorithm is developed to estimate 22 temperature-dependent Pitzer-equation parameters. The sodium sulfate reparameterization reduces the overall standard error (SE) from 0.393 with the SMW Pitzer-equation parameters to 0.155. Similarly, the magnesium sulfate reparameterization reduces the SE from 0.335 to 0.124. In addition to the sulfate reparameterization, five additional sulfate minerals are included in the model, which allows a more complete treatment of sulfate chemistry in the Na-K-Mg-Ca-Cl-SO 4-H 2O system. Application of the model to seawater evaporation predicts gypsum precipitation at a seawater concentration factor (SCF) of 3.37 and halite precipitation at an SCF of 10.56, which are in good agreement with previous experimental and theoretical estimates. Application of the model to seawater freezing helps explain the two pathways for seawater freezing. Along the thermodynamically stable "Gitterman pathway," calcium precipitates as gypsum and the seawater eutectic is -36.2°C. Along the metastable "Ringer-Nelson-Thompson pathway," calcium precipitates as antarcticite and the seawater eutectic is -53.8°C.

Comparative analysis of the cold acclimation and freezing tolerance capacities of seven diploid Brachypodium distachyon accessions

PubMed Central

Colton-Gagnon, Katia; Ali-Benali, Mohamed Ali; Mayer, Boris F.; Dionne, Rachel; Bertrand, Annick; Do Carmo, Sonia; Charron, Jean-Benoit

2014-01-01

Background and Aims Cold is a major constraint for cereal cultivation under temperate climates. Winter-hardy plants interpret seasonal changes and can acquire the ability to resist sub-zero temperatures. This cold acclimation process is associated with physiological, biochemical and molecular alterations in cereals. Brachypodium distachyon is considered a powerful model system to study the response of temperate cereals to adverse environmental conditions. To date, little is known about the cold acclimation and freezing tolerance capacities of Brachypodium. The main objective of this study was to evaluate the cold hardiness of seven diploid Brachypodium accessions. Methods An integrated approach, involving monitoring of phenological indicators along with expression profiling of the major vernalization regulator VRN1 orthologue, was followed. In parallel, soluble sugars and proline contents were determined along with expression profiles of two COR genes in plants exposed to low temperatures. Finally, whole-plant freezing tests were performed to evaluate the freezing tolerance capacity of Brachypodium. Key Results Cold treatment accelerated the transition from the vegetative to the reproductive phase in all diploid Brachypodium accessions tested. In addition, low temperature exposure triggered the gradual accumulation of BradiVRN1 transcripts in all accessions tested. These accessions exhibited a clear cold acclimation response by progressively accumulating proline, sugars and COR gene transcripts. However, whole-plant freezing tests revealed that these seven diploid accessions only have a limited capacity to develop freezing tolerance when compared with winter varieties of temperate cereals such as wheat and barley. Furthermore, little difference in terms of survival was observed among the accessions tested despite their previous classification as either spring or winter genotypes. Conclusions This study is the first to characterize the freezing tolerance capacities of B. distachyon and provides strong evidence that some diploid accessions such as Bd21 have a facultative growth habit. PMID:24323247

Ikaite solubility in seawater-derived brines at 1 atm and sub-zero temperatures to 265 K

NASA Astrophysics Data System (ADS)

Papadimitriou, Stathys; Kennedy, Hilary; Kennedy, Paul; Thomas, David N.

2013-05-01

The concentration-based (stoichiometric) equilibrium solubility product of ikaite (CaCO3·6H2O) in seawater and cryogenic seawater-derived brines was determined at 1 atm total pressure over the temperature range from -1.1 to -7.5 °C and the salinity range from 34 to 124 in temperature-salinity pairs representative of sea ice brines. The solubility measurements were obtained in solutions that were undersaturated and supersaturated with respect to ikaite by equilibration with CO2/N2 gas mixtures of known pCO2 (20-400 μatm). The solutions were then equilibrated with synthetic ikaite (seed) for up to 3 months in a closed system. Arrival of the solid-solution system at a long-term chemical equilibrium was indicated by attainment of constant chemical solution composition with respect to total dissolved calcium, total dissolved inorganic carbon, and total alkalinity. Using these measurements, the stoichiometric equilibrium solubility product of ikaite (Ksp,ikaite∗=[Ca][CO32-], in molkgsolution-2) was determined, with the carbonate ion concentration computed from the measured total alkalinity and total dissolved inorganic carbon concentrations. The computed carbonate ion concentration and, by extension, the Ksp,ikaite∗ are both contingent on solving the system of equations that describe the parameters of the CO2 system in seawater by extrapolation to the experimental salinity and temperature conditions. The results show that the pKsp,ikaite∗=-logKsp,ikaite∗ in seawater of salinity 34 at -1.1 °C was 5.362 ± 0.004 and that the pKsp,ikaite∗ in sea ice at the freezing point of brines of salinity greater than 34 can be described as a function of temperature (T, in K) by the equation, pKsp,ikaite∗=-15489.09608+623443.70216T-1+2355.14596lnT, in the temperature range of 265.15 K < T < 271.15 K (-8 °C < t < -2 °C). Brines of low pCO2 (20 μatm) yielded a much slower (>1 month) approach to chemical equilibrium when incubated without seeding ikaite crystals. Simple modeling indicated that ikaite should not precipitate from sea ice brines evolving under closed system conditions with respect to CO2 exchange. To facilitate ikaite precipitation, brine pCO2 reduction due to photosynthesis or CO2 degassing, or both, is necessary.

Cooling rate and starvation affect supercooling point and cold tolerance of the Khapra beetle, Trogoderma granarium Everts fourth instar larvae (Coleoptera: Dermestidae).

PubMed

Mohammadzadeh, M; Izadi, H

2018-01-01

Trogoderma granarium Everts (Coleoptera: Dermestidae) is an important insect pest of stored products. In this study, the survival strategies of T. granarium fourth instar larvae were investigated at different sub-zero temperatures following different cooling rates, acclimation to different relative humidity (RH) and different starvation times. Our results show that larvae of T. granarium are freeze-intolerant. There was a strong link between cooling rates and supercooling point, which means the slower the decrease in temperature, the lower the supercooling point. Trehalose content was greater in insects cooled at a rate of 0.5°C/min. According to results, the RH did not affect supercooling point. However, acclimation to an RH of 25% increased mortality following exposure to - 10°C/24h. The time necessary to reach 95% mortality was 1737h and 428h at - 5°C and - 10°C. The lowest lipid and trehalose content was detected in insects acclimated to 25% RH, although, the different RH treatments did not significantly affect glycogen content of T. granarium larvae. The supercooling point of larvae was gradually increased following starvation. By contrast, fed larvae had the greatest lipid, glycogen, and trehalose content, and insects starved for eight days had the lowest energy contents. There was a sharp decline in the survival of larvae between - 11 and - 18°C after 1h exposure. Our results indicate the effects of cooling rate and starvation on energy reserves and survival of T. granarium. We conclude that T. granarium may not survive under similar stress conditions of the stored products. Copyright © 2017 Elsevier Ltd. All rights reserved.

An Extrapolation of a Radical Equation More Accurately Predicts Shelf Life of Frozen Biological Matrices.

PubMed

De Vore, Karl W; Fatahi, Nadia M; Sass, John E

2016-08-01

Arrhenius modeling of analyte recovery at increased temperatures to predict long-term colder storage stability of biological raw materials, reagents, calibrators, and controls is standard practice in the diagnostics industry. Predicting subzero temperature stability using the same practice is frequently criticized but nevertheless heavily relied upon. We compared the ability to predict analyte recovery during frozen storage using 3 separate strategies: traditional accelerated studies with Arrhenius modeling, and extrapolation of recovery at 20% of shelf life using either ordinary least squares or a radical equation y = B1x(0.5) + B0. Computer simulations were performed to establish equivalence of statistical power to discern the expected changes during frozen storage or accelerated stress. This was followed by actual predictive and follow-up confirmatory testing of 12 chemistry and immunoassay analytes. Linear extrapolations tended to be the most conservative in the predicted percent recovery, reducing customer and patient risk. However, the majority of analytes followed a rate of change that slowed over time, which was fit best to a radical equation of the form y = B1x(0.5) + B0. Other evidence strongly suggested that the slowing of the rate was not due to higher-order kinetics, but to changes in the matrix during storage. Predicting shelf life of frozen products through extrapolation of early initial real-time storage analyte recovery should be considered the most accurate method. Although in this study the time required for a prediction was longer than a typical accelerated testing protocol, there are less potential sources of error, reduced costs, and a lower expenditure of resources. © 2016 American Association for Clinical Chemistry.

UV Radiation and Visible Light Induce hsp70 Gene Expression in the Antarctic Psychrophilic Ciliate Euplotes focardii.

PubMed

Fulgentini, Lorenzo; Passini, Valerio; Colombetti, Giuliano; Miceli, Cristina; La Terza, Antonietta; Marangoni, Roberto

2015-08-01

The psychrophilic ciliate Euplotes focardii inhabits the shallow marine coastal sediments of Antarctica, where, over millions of years of evolution, it has reached a strict molecular adaptation to such a constant-temperature environment (about -2 °C). This long evolution at sub-zero temperatures has made E. focardii unable to respond to heat stress with the activation of its heat shock protein (hsp) 70 genes. These genes can, however, be expressed in response to other stresses, like the oxidative one, thus indicating that the molecular adaptation has exclusively altered the heat stress signaling pathways, while it has preserved hsp70 gene activation in response to other environmental stressors. Since radiative stress has proved to be affine to oxidative stress in several organisms, we investigated the capability of UV radiation to induce hsp70 transcription. E. focardii cell cultures were exposed to several different irradiation regimes, ranging from visible only to a mixture of visible, UV-A and UV-B. The irradiation values of each spectral band have been set to be comparable with those recorded in a typical Antarctic spring. Using Northern blot analysis, we measured the expression level of hsp70 immediately after irradiation (0-h-labeled samples), 1 h, and 2 h from the end of the irradiation. Surprisingly, our results showed that besides UV radiation, the visible light was also able to induce hsp70 expression in E. focardii. Moreover, spectrophotometric measurements have revealed no detectable endogenous pigments in E. focardii, making it difficult to propose a possible explanation for the visible light induction of its hsp70 genes. Further research is needed to conclusively clarify this point.

Deleterious effects of repeated cold exposure in a freeze-tolerant sub-Antarctic caterpillar.

PubMed

Sinclair, Brent J; Chown, Steven L

2005-03-01

Multiple freeze-thaw cycles are common in alpine, polar and temperate habitats. We investigated the effects of five consecutive cycles of approx. -5 degrees C on the freeze-tolerant larvae of Pringleophaga marioni Viette (Lepidoptera: Tineidae) on sub-Antarctic Marion Island. The likelihood of freezing was positively correlated with body mass, and decreased from 70% of caterpillars that froze on initial exposure to 55% of caterpillars that froze on subsequent exposures; however, caterpillars retained their freeze tolerance and did not appear to switch to a freeze-avoiding strategy. Apart from an increase in gut water, there was no difference in body composition of caterpillars frozen 0 to 5 times, suggesting that the observed effects were not due to freezing, but rather to exposure to cold per se. Repeated cold exposure did not result in mortality, but led to decreased mass, largely accounted for by a decreased gut mass caused by cessation of feeding by caterpillars. Treatment caterpillars had fragile guts with increased lipid content, suggesting damage to the gut epithelium. These effects persisted for 5 days after the final exposure to cold, and after 30 days, treatment caterpillars had regained their pre-exposure mass, whereas their control counterparts had significantly gained mass. We show that repeated cold exposure does occur in the field, and suggest that this may be responsible for the long life cycle in P. marioni. Although mean temperatures are increasing on Marion Island, several climate change scenarios predict an increase in exposures to sub-zero temperatures, which would result in an increased generation time for P. marioni. Coupled with increased predation from introduced house mice on Marion Island, this could have severe consequences for the P. marioni population.

Recombinant Dendroides canadensis antifreeze proteins as potential ingredients in cryopreservation solutions.

PubMed

Halwani, Dina O; Brockbank, Kelvin G M; Duman, John G; Campbell, Lia H

2014-06-01

Expanding cryopreservation methods to include a wider range of cell types, such as those sensitive to freezing, is needed for maintaining the viability of cell-based regenerative medicine products. Conventional cryopreservation protocols, which include use of cryoprotectants such as dimethylsulfoxide (Me2SO), have not prevented ice-induced damage to cell and tissue matrices during freezing. A family of antifreeze proteins (AFPs) produced in the larvae of the beetle, Dendroides canadensis allow this insect to survive subzero temperatures as low as -26°C. This study is an assessment of the effect of the four hemolymph D. canadensis AFPs (DAFPs) on the supercooling (nucleating) temperature, ice structure patterns and viability of the A10 cell line derived from the thoracic aorta of embryonic rat. Cryoprotectant solution cocktails containing combinations of DAFPs in concentrations ranging from 0 to 3mg/mL in Unisol base mixed with 1M Me2SO were first evaluated by cryomicroscopy. Combining multiple DAFPs demonstrated significant supercooling point depressing activity (∼9°C) when compared to single DAFPs and/or conventional 1M Me2SO control solutions. Concentrations of DAFPs as low as 1 μg/mL were sufficient to trigger this effect. In addition, significantly improved A10 smooth muscle cell viability was observed in cryopreservation experiments with low DAFP-6 and DAFP-2 concentrations in combination with Me2SO. No significant improvement in viability was observed with either DAFP-1 or DAFP-4. Low and effective DAFP concentrations are advantageous because they minimize concerns regarding cell cytotoxicity and manufacturing cost. These findings support the potential of incorporating DAFPs in solutions used to cryopreserve cells and tissues. Copyright © 2014 Elsevier Inc. All rights reserved.

The mineralogic evolution of the Martian surface through time: Implications from chemical reaction path modeling studies

NASA Technical Reports Server (NTRS)

Plumlee, G. S.; Ridley, W. I.; Debraal, J. D.; Reed, M. H.

1993-01-01

Chemical reaction path calculations were used to model the minerals that might have formed at or near the Martian surface as a result of volcano or meteorite impact driven hydrothermal systems; weathering at the Martian surface during an early warm, wet climate; and near-zero or sub-zero C brine-regolith reactions in the current cold climate. Although the chemical reaction path calculations carried out do not define the exact mineralogical evolution of the Martian surface over time, they do place valuable geochemical constraints on the types of minerals that formed from an aqueous phase under various surficial and geochemically complex conditions.

A revised Pitzer model for low-temperature soluble salt assemblages at the Phoenix site, Mars

NASA Astrophysics Data System (ADS)

Toner, J. D.; Catling, D. C.; Light, B.

2015-10-01

The Wet Chemistry Laboratory (WCL) on the Mars Phoenix Lander measured ions in a soil-water extraction and found Na+, K+, H+ (pH), Ca2+, Mg2+, SO42-, ClO4-, and Cl-. Equilibrium models offer insights into salt phases that were originally present in the Phoenix soil, which dissolved to form the measured WCL solution; however, there are few experimental datasets for single cation perchlorates (ClO4-), and none for mixed perchlorates, at low temperatures, which are needed to build models. In this study, we measure ice and salt solubilities in binary and ternary solutions in the Na-Ca-Mg-ClO4 system, and then use this data, along with existing data, to construct a low-temperature Pitzer model for perchlorate brines. We then apply our model to a nominal WCL solution. Previous studies have modeled either freezing of a WCL solution or evaporation at a single temperature. For the first time, we model evaporation at subzero temperatures, which is relevant for dehydration conditions that might occur at the Phoenix site. Our model indicates that a freezing WCL solution will form ice, KClO4, hydromagnesite (3MgCO3·Mg(OH)2·3H2O), calcite (CaCO3), meridianiite (MgSO4·11H2O), MgCl2·12H2O, NaClO4·2H2O, and Mg(ClO4)2·6H2O at the eutectic (209 K). The total water held in hydrated salt phases at the eutectic is ∼1.2 wt.%, which is much greater than hydrated water contents when evaporation is modeled at 298.15 K (∼0.3 wt.%). Evaporation of WCL solutions at lower temperatures (down to 210 K) results in lower water activities and the formation of more dehydrated minerals, e.g. kieserite (MgSO4·H2O) instead of meridianiite. Potentially habitable brines, with water activity aw > 0.6, can occur when soil temperatures are above 220 K and when the soil liquid water content is greater than 0.4 wt.% (100 ×gH2O gsoil-1). In general, modeling indicates that mineral assemblages derived from WCL-type solutions are characteristic of the soil temperature, water content, and water activity conditions under which they formed, and are useful indicators of past environmental conditions.

Presence of supercooling-facilitating (anti-ice nucleation) hydrolyzable tannins in deep supercooling xylem parenchyma cells in Cercidiphyllum japonicum.

PubMed

Wang, Donghui; Kasuga, Jun; Kuwabara, Chikako; Endoh, Keita; Fukushi, Yukiharu; Fujikawa, Seizo; Arakawa, Keita

2012-04-01

Xylem parenchyma cells (XPCs) in trees adapt to subzero temperatures by deep supercooling. Our previous study indicated the possibility of the presence of diverse kinds of supercooling-facilitating (SCF; anti-ice nucleation) substances in XPCs of katsura tree (Cercidiphyllum japonicum), all of which might have an important role in deep supercooling of XPCs. In the previous study, a few kinds of SCF flavonol glycosides were identified. Thus, in the present study, we tried to identify other kinds of SCF substances in XPCs of katsura tree. SCF substances were purified from xylem extracts by silica gel column chromatography and Sephadex LH-20 column chromatography. Then, four SCF substances isolated were identified by UV, mass and nuclear magnetic resonance analyses. The results showed that the four kinds of hydrolyzable gallotannins, 2,2',5-tri-O-galloyl-α,β-D-hamamelose (trigalloyl Ham or kurigalin), 1,2,6-tri-O-galloyl-β-D-glucopyranoside (trigalloyl Glc), 1,2,3,6-tetra-O-galloyl-β-D-glucopyranoside (tetragalloyl Glc) and 1,2,3,4,6-penta-O-galloyl-β-D-glucopyranoside (pentagalloyl Glc), in XPCs exhibited supercooling capabilities in the range of 1.5-4.5°C, at a concentration of 1 mg mL⁻¹. These SCF substances, including flavonol glycosides and hydrolyzable gallotannins, may contribute to the supercooling in XPCs of katsura tree.

Precipitation of salts in freezing seawater and ozone depletion events: a status report

NASA Astrophysics Data System (ADS)

Morin, S.; Marion, G. M.; von Glasow, R.; Voisin, D.; Bouchez, J.; Savarino, J.

2008-12-01

In springtime, the polar marine boundary layer exhibits drastic ozone depletion events (ODEs), associated with elevated bromine oxide (BrO) mixing ratios. The current interpretation of this peculiar chemistry requires the existence of acid and bromide-enriched surfaces to heterogeneously promote and sustain ODEs. Sander et al. (2006) have proposed that calcium carbonate (CaCO3) precipitation in any seawater-derived medium could potentially decrease its alkalinity, making it easier for atmospheric acids such as HNO3 and H2SO4 to acidify it. We performed simulations using the state-of-the-art FREZCHEM model, capable of handling the thermodynamics of concentrated electrolyte solutions, to try to reproduce their results, and found that when ikaite (CaCO3·6H2O) rather than calcite (CaCO3) precipitates, there is no such effect on alkalinity. Given that ikaite has recently been identified in Antarctic brines (Dieckmann et al., 2008), our results show that great caution should be exercised when using the results of Sander et al. (2006), and reveal the urgent need of laboratory investigations on the actual link(s) between bromine activation and the pH of the surfaces on which it is supposed to take place at subzero temperature. In addition, the evolution of the Cl/Br ratio in the brine during freezing was computed using FREZCHEM, taking into account Br substitutions in Cl-containing salts.

Long-term variability of dust events in Iceland (1949-2011)

NASA Astrophysics Data System (ADS)

Dagsson-Waldhauserova, P.; Arnalds, O.; Olafsson, H.

2014-06-01

Long-term frequency of atmospheric dust observations was investigated for the southern part of Iceland and merged with results obtained from the Northeast Iceland (Dagsson-Waldhauserova et al., 2013). In total, over 34 dust days per year on average occurred in Iceland based on conventionally used synoptic codes for dust. Including codes 04-06 into the criteria for dust observations, the frequency was 135 dust days annually. The Sea Level Pressure (SLP) oscillation controlled whether dust events occurred in NE (16.4 dust days annually) or in southern part of Iceland (about 18 dust days annually). The most dust-frequent decade in S Iceland was the 1960s while the most frequent decade in NE Iceland was the 2000s. A total of 32 severe dust storms (visibility < 500 m) was observed in Iceland with the highest frequency during the 2000s in S Iceland. The Arctic dust events (NE Iceland) were typically warm and during summer/autumn (May-September) while the Sub-Arctic dust events (S Iceland) were mainly cold and during winter/spring (March-May). About half of dust events in S Iceland occurred in winter or at sub-zero temperatures. A good correlation was found between PM10 concentrations and visibility during dust observations at the stations Vik and Storhofdi. This study shows that Iceland is among the dustiest areas of the world and dust is emitted the year-round.

Effects of using slurry ice during transportation on the microbiological, chemical, and sensory assessments of aquacultured sea bass (Dicentrarchus labrax) stored at 4 degrees C.

PubMed

Cakli, Sukran; Kilinc, Berna; Dincer, Tolga; Tolasa, Sebnem

2006-01-01

Slurry ice, a biphasic system consisting of small spherical ice crystals surrounded by seawater at subzero temperature, was evaluated as a new chilled storage method for whole sea bass (Dicentrarchus labrax) a sparidae fish species of remarkable commercial interests. In this study two different group of chilling methods were used during transportation; in slurry ice packaged (Group A), and flake ice packaged (Group B). The effect of this advanced system during transportation on quality losses and the shelf life of aquacultured sea bass was evaluated. Mesophilic counts for sea bass exceeded 7 log cfu/g, which is considered the maximum level for acceptability for freshwater and marine fish after 13 days for groups A and B. On day 13 TVB-N values of groups A and B, reached the legal limits (35 mg/100 g set for TVB-N) for consumption. According to the results of sensory analyses, up to day 9 all the groups were determined as "acceptable" but on day 13 the groups A and B were no longer acceptable. The main negative aspect related to quality loss in slurry ice group corresponded to the appearance of eyes and gills. Using slurry ice during transportation did not extend the shelf life of sea bass stored at 4 degrees C.

Telemedicine in the Himalayas: Operational Challenges-A Preliminary Report.

PubMed

Ganapathy, Krishnan; Chawdhry, Vineet; Premanand, Satgunam; Sarma, Arunabh; Chandralekha, Jothivaithilingam; Kumar, Kotte Yogesh; Kumar, Saroj; Guleri, Rajesh

2016-10-01

Nonavailability of quality healthcare in mountainous, isolated, inaccessible sparsely populated regions is a universal problem. In this project, remote virtual healthcare was provided at Keylong and Kaza in Himachal Pradesh (HP) in North India. This innovative public-private partnership (PPP) provides 24/7 affordable healthcare to an alpine community where people commute 20-50 km for primary and 250 km for secondary healthcare services. Following a need assessment study, an MoU was signed by Apollo Hospitals in January 2015 with the National Health Mission. The government paid for all services delivered, Capital Expenditure (CAPEX) and Operating Expenditure (OPEX). Noncompliance to auditable weekly and monthly program MIS would result in penalties. Apollo Telehealth Services customized a turnkey solution, end-to-end, on a program management approach with measurable milestones and monthly reports. Key health issues in the region were identified. Very Small Aperture Terminals were installed amidst landslides and subzero temperatures. In February and March 2015, staff recruited from the community and local government staff were trained in Chennai. A major cultural transformation had to be effected. Urban teleconsultants were sensitized for community interaction, while deploying cutting- edge technology. Case records were audited. In the first 42 weeks, 2,213 teleconsults were provided, including 171 emergencies. Telelaboratory services and telehealth education programs have also been added. Evaluation confirms that delivering remote healthcare in inhospitable terrains in a PPP mode is effective.

Testing and ground calibration of DREAMS-H relative humidity device

NASA Astrophysics Data System (ADS)

Genzer, Maria; Hieta, Maria; Nikkanen, Timo; Schmidt, Walter; Kemppinen, Osku; Harri, Ari-Matti; Haukka, Harri

2015-04-01

DREAMS (Dust Characterization, Risk Assessment and Environmental Analyzer on the Martian Surface) instrument suite is to be launched as part of the ESA ExoMars 2016/Schiaparelli lander. DREAMS consists of an environmental package for monitoring temperature, pressure, relative humidity, winds and dust opacity, as well as atmospheric electricity of Martian atmosphere. The DREAMS instruments and scientific goals are described in [1]. Here we describe testing and ground calibration of the relative humidity device, DREAMS-H, provided to the DREAMS payload by the Finnish Meteorological Institute and based on proprietary technology of Vaisala, Inc. The same kind of device is part of the REMS instrument package onboard MSL Curiosity Rover [2][3]. DREAMS-H is based on Vaisala Humicap® technology adapted for use in Martian environment by the Finnish Meteorological Institute. The device is very small and lightweighed, with total mass less than 20 g and consuming only 15 mW of power. The Humicap® sensor heads contain an active polymer film that changes its capacitance as function of relative humidity, with 0% to 100% RH measurement range. The dynamic range of the device gets smaller with sensor temperature, being in -70°C approximately 30% of the dynamic range in 0°C [3]. Good-quality relative humidity measurements require knowing the temperature of the environment in which relative humidity is measured. An important part of DREAMS-H calibration was temperature calibration of Vaisala Thermocap® temperature sensors used for housekeeping temperature measurements of the DREAMS-H device. For this, several temperature points in the desired operational range were measured with 0.1°C accuracy traceable to national standards. The main part of humidity calibration of DREAMS-H flight models was done in subzero temperatures in a humidity generator of the Finnish Center of Metrology and Accreditation (MIKES). Several relative humidity points ranging from almost dry to almost wet were measured at several temperature points between 0°C and -70°C. Dry baseline was established in vacuum measurements at the Finnish Meteorological Institute. In addition to stable relative humidity points, measurements in changing relative humidity and temperature were done in order to get information about the lag of the sensor. References: 1] Esposito, F. et al: The DREAMS Experiment on the ExoMars 2016 Mission for the Study of Martian Environment during the Dust Storm Season, The Fifth International Workshop on the Mars Atmosphere, 13-16 January 2014, Oxford, UK, 2014. [2] Gómez-Elvira, J. et al.: REMS: The Environmental Sensor Suite for the Mars Science Laboratory Rover, Space Sci. Rev., 170, pp. 583-640, 2012. [3] Harri, A.-M. et al.: Mars Science Laboratory Relative Humidity Observations - Initial Results, JGR Planets, Vol 119 Issue 9, pp. 2132-2147, 2014.

Arctic Haze Analysis

NASA Astrophysics Data System (ADS)

Mei, Linlu; Xue, Yong

2013-04-01

The Arctic atmosphere is perturbed by nature/anthropogenic aerosol sources known as the Arctic haze, was firstly observed in 1956 by J. Murray Mitchell in Alaska (Mitchell, 1956). Pacyna and Shaw (1992) summarized that Arctic haze is a mixture of anthropogenic and natural pollutants from a variety of sources in different geographical areas at altitudes from 2 to 4 or 5 km while the source for layers of polluted air at altitudes below 2.5 km mainly comes from episodic transportation of anthropogenic sources situated closer to the Arctic. Arctic haze of low troposphere was found to be of a very strong seasonal variation characterized by a summer minimum and a winter maximum in Alaskan (Barrie, 1986; Shaw, 1995) and other Arctic region (Xie and Hopke, 1999). An anthropogenic factor dominated by together with metallic species like Pb, Zn, V, As, Sb, In, etc. and nature source such as sea salt factor consisting mainly of Cl, Na, and K (Xie and Hopke, 1999), dust containing Fe, Al and so on (Rahn et al.,1977). Black carbon and soot can also be included during summer time because of the mix of smoke from wildfires. The Arctic air mass is a unique meteorological feature of the troposphere characterized by sub-zero temperatures, little precipitation, stable stratification that prevents strong vertical mixing and low levels of solar radiations (Barrie, 1986), causing less pollutants was scavenged, the major revival pathway for particulates from the atmosphere in Arctic (Shaw, 1981, 1995; Heintzenberg and Larssen, 1983). Due to the special meteorological condition mentioned above, we can conclude that Eurasian is the main contributor of the Arctic pollutants and the strong transport into the Arctic from Eurasia during winter caused by the high pressure of the climatologically persistent Siberian high pressure region (Barrie, 1986). The paper intends to address the atmospheric characteristics of Arctic haze by comparing the clear day and haze day using different dataset, including satellite remote sensing, ground-based observations and modelling. The key question is which information should be used for analysis and how to integrate the source information. The behavior of different atmospheric parameters as described in the paper is consistent and the analysis using satellite atmospheric parameters is in line with synoptic charts. Hence the different data sources are complementary and the results support each other (Mei et al., 2011). In the paper, Aerosol Optical Depth (AOD) from both satellite retrieval data and ground-based measurements were analyzed the characteristic, especially the absorption. We also discuss the effect of Arctic haze to the Arctic temperature, snow albedo and arctic flux in details.

Mobilization of retrotransposons as a cause of chromosomal diversification and rapid speciation: the case for the Antarctic teleost genus Trematomus.

PubMed

Auvinet, J; Graça, P; Belkadi, L; Petit, L; Bonnivard, E; Dettaï, A; Detrich, W H; Ozouf-Costaz, C; Higuet, D

2018-05-09

The importance of transposable elements (TEs) in the genomic remodeling and chromosomal rearrangements that accompany lineage diversification in vertebrates remains the subject of debate. The major impediment to understanding the roles of TEs in genome evolution is the lack of comparative and integrative analyses on complete taxonomic groups. To help overcome this problem, we have focused on the Antarctic teleost genus Trematomus (Notothenioidei: Nototheniidae), as they experienced rapid speciation accompanied by dramatic chromosomal diversity. Here we apply a multi-strategy approach to determine the role of large-scale TE mobilization in chromosomal diversification within Trematomus species. Despite the extensive chromosomal rearrangements observed in Trematomus species, our measurements revealed strong interspecific genome size conservation. After identifying the DIRS1, Gypsy and Copia retrotransposon superfamilies in genomes of 13 nototheniid species, we evaluated their diversity, abundance (copy numbers) and chromosomal distribution. Four families of DIRS1, nine of Gypsy, and two of Copia were highly conserved in these genomes; DIRS1 being the most represented within Trematomus genomes. Fluorescence in situ hybridization mapping showed preferential accumulation of DIRS1 in centromeric and pericentromeric regions, both in Trematomus and other nototheniid species, but not in outgroups: species of the Sub-Antarctic notothenioid families Bovichtidae and Eleginopsidae, and the non-notothenioid family Percidae. In contrast to the outgroups, High-Antarctic notothenioid species, including the genus Trematomus, were subjected to strong environmental stresses involving repeated bouts of warming above the freezing point of seawater and cooling to sub-zero temperatures on the Antarctic continental shelf during the past 40 millions of years (My). As a consequence of these repetitive environmental changes, including thermal shocks; a breakdown of epigenetic regulation that normally represses TE activity may have led to sequential waves of TE activation within their genomes. The predominance of DIRS1 in Trematomus species, their transposition mechanism, and their strategic location in "hot spots" of insertion on chromosomes are likely to have facilitated nonhomologous recombination, thereby increasing genomic rearrangements. The resulting centric and tandem fusions and fissions would favor the rapid lineage diversification, characteristic of the nototheniid adaptive radiation.

D:L-AMINO Acids and the Turnover of Microbial Biomass

NASA Astrophysics Data System (ADS)

Lomstein, B. A.; Braun, S.; Mhatre, S. S.; Jørgensen, B. B.

2015-12-01

Decades of ocean drilling have demonstrated wide spread microbial life in deep sub-seafloor sediment, and surprisingly high microbial cell numbers. Despite the ubiquity of life in the deep biosphere, the large community sizes and the low energy fluxes in the vast buried ecosystem are still poorly understood. It is not know whether organisms of the deep biosphere are specifically adapted to extremely low energy fluxes or whether most of the observed cells are in a maintenance state. Recently we developed and applied a new culture independent approach - the D:L-amino acid model - to quantify the turnover times of living microbial biomass, microbial necromass and mean metabolic rates. This approach is based on the built-in molecular clock in amino acids that very slowly undergo chemical racemization until they reach an even mixture of L- and D- forms, unless microorganisms spend energy to keep them in the L-form that dominates in living organisms. The approach combines sensitive analyses of amino acids, the unique bacterial endospore marker (dipicolinic acid) with racemization dynamics of stereo-isomeric amino acids. Based on a heating experiment, we recently reported kinetic parameters for racemization of aspartic acid, glutamic acid, serine and alanine in bulk sediment from Aarhus Bay, Denmark. The obtained racemization rate constants were faster than the racemization rate constants of free amino acids, which we have previously applied in Holocene sediment from Aarhus Bay and in up to 10 mio yr old sediment from ODP Leg 201. Another important input parameter for the D:L-amino acid model is the cellular carbon content. It has recently been suggested that the cellular carbon content most likely is lower than previously thought. In recognition of these new findings, previously published data based on the D:L-amino acid model were recalculated and will be presented together with new data from an Arctic Holocene setting with constant sub-zero temperatures.

Polar Gateways Arctic Circle Sunrise Conference 2008, Barrow, Alaska: IHY-IPY Outreach on Exploration of Polar and Icy Worlds in The Solar System

NASA Astrophysics Data System (ADS)

Cooper, John F.; Kauristie, K.; Weatherwax, A. T.; Sheehan, G. W.; Smith, R. W.; Sandahl, I.; Østgaard, N.; Chernouss, S.; Moore, M. H.; Peticolas, L. M.; Senske, D. A.; Thompson, B. J.; Tamppari, L. K.; Lewis, E. M.

2008-09-01

Polar, heliophysical, and planetary science topics related to the International Heliophysical and Polar Years 2007-2009 were addressed during this circumpolar video conference hosted January 23-29, 2008 at the new Barrow Arctic Research Center of the Barrow Arctic Science Consortium in Barrow, Alaska. This conference was planned as an IHY-IPY event science outreach event bringing together scientists and educational specialists for the first week of sunrise at subzero Arctic temperatures in Barrow. Science presentations spanned the solar system from the polar Sun to Earth, Moon, Mars, Jupiter, Saturn, and the Kuiper Belt. On-site participants experienced look and feel of icy worlds like Europa and Titan by being in the Barrow tundra and sea ice environment and by going "on the ice" during snowmobile expeditions to the near-shore sea ice environment and to Point Barrow, closest geographic point in the U.S. to the North Pole. Many science presentations were made remotely via video conference or teleconference from Sweden, Norway, Russia, Canada, Antarctica, and the United States, spanning up to thirteen time zones (Alaska to Russia) at various times. Extensive educational outreach activities were conducted with the local Barrow and Alaska North Slope communities and through the NASA Digital Learning Network live from the "top of the world" at Barrow. The Sun-Earth Day team from Goddard, and a videographer from the Passport to Knowledge project, carried out extensive educational interviews with many participants and native Inupiaq Eskimo residents of Barrow. Video and podcast recordings of selected interviews are available at http://sunearthday.nasa.gov/2008/multimedia/podcasts.php. Excerpts from these and other interviews will be included in a new high definition video documentary called "From the Sun to the Stars: The New Science of Heliophysics" from Passport to Knowledge that will later broadcast on NASA TV and other educational networks. Full conference proceedings are accessible at http://polargateways2008.org/.

Ice nucleation properties of atmospheric aerosol particles collected during a field campaign in Cyprus

NASA Astrophysics Data System (ADS)

Yordanova, Petya; Maier, Stefanie; Lang-Yona, Naama; Tamm, Alexandra; Meusel, Hannah; Pöschl, Ulrich; Weber, Bettina; Fröhlich-Nowoisky, Janine

2017-04-01

Atmospheric aerosol particles, including desert and soil dust as well as marine aerosols, are well known to act as ice nuclei (IN) and thus have been investigated in numerous ice nucleation studies. Based on their cloud condensation nuclei potential and their impacts on radiative properties of clouds (via scattering and absorption of solar radiation), aerosol particles may significantly affect the cloud and precipitation development. Atmospheric aerosols of the Eastern Mediterranean have been described to be dominated by desert dust, but only little is known on their composition and ice nucleating properties. In this study we investigated the ice nucleating ability of total suspended particles (TSP), collected at the remote site Agia Marina Xyliatou on Cyprus during a field campaign in April 2016. Airborne TSP samples containing air masses of various types such as African (Saharan) and Arabian dust and European and Middle Eastern pollution were collected on glass fiber filters at 24 h intervals. Sampling was performed ˜5 m above ground level and ˜521 m above sea level. During the sampling period, two major dust storms (PM 10max 118 μg/m3 and 66 μg/m3) and a rain event (rainfall amount: 3.4 mm) were documented. Chemical and physical characterizations of the particles were analyzed experimentally through filtration, thermal, chemical and enzyme treatments. Immersion freezing experiments were performed at relatively high subzero temperatures (-1 to -15˚ C) using the mono ice nucleation array. Preliminary results indicate that highest IN particle numbers (INPs) occurred during the second dust storm event with lower particle concentrations. Treatments at 60˚ C lead to a gradual IN deactivation, indicating the presence of biological INPs, which were observed to be larger than 300 kDa. Additional results originating from this study will be shown. Acknowledgement: This work was funded by the DFG Ice Nuclei Research Unit (INUIT).

Hydrocarbon-degrading bacteria in deep-water subarctic sediments (Faroe-Shetland Channel).

PubMed

Gontikaki, Evangelia; Potts, Lloyd; Anderson, James A; Witte, Ursula

2018-06-21

The aim of this study was the baseline description of oil-degrading sediment bacteria along a depth transect in the Faroe-Shetland Channel (FSC) and the identification of biomarker taxa for the detection of oil contamination in FSC sediments. Oil-degrading sediment bacteria from 135, 500 and 1000 m were enriched in cultures with crude oil as the sole carbon source (at 12, 5 and 0°C respectively). The enriched communities were studied using culture-dependent and culture-independent (clone libraries) techniques. Isolated bacterial strains were tested for hydrocarbon degradation capability. Bacterial isolates included well-known oil-degrading taxa and several that are reported in that capacity for the first time (Sulfitobacter, Ahrensia, Belliella, Chryseobacterium). The orders Oceanospirillales and Alteromonadales dominated clone libraries in all stations but significant differences occurred at genus level particularly between the shallow and the deep, cold-water stations. Alcanivorax constituted 64% of clones at FSC135 but was absent at deeper stations. Pseudoalteromonas and Oleispira dominated the bacterial community at 500 and 1000 m. The genus Oleispira emerged as a major player in the early stages of crude oil degradation in deep-sea sediments of the FSC particularly at sub-zero temperatures. This finding is offering a direction for future research into biomonitoring tools for the detection of low levels of crude oil contamination in the deep FSC, and possibly high latitude cold waters in general. Oil and gas exploration in the FSC occurs at depths >1000 m but baseline environmental data necessary for the assessment of ecosystem recovery to pre-spill conditions in the event of an oil spill are lacking. This study will contribute to our ability to assess the impact of oil release in the FSC and guide the direction of bioremediation strategies tailored to the area. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Polar Gateways Arctic Circle Sunrise Conference 2008, Barrow, Alaska: IHY-IPY Outreach on Exploration of Polar and Icy Worlds in the Solar System

NASA Technical Reports Server (NTRS)

Cooper, John F.; Kauristie, Kirsti; Weatherwax, Allan T.; Sheehan, Glenn W.; Smith, Roger W.; Sandahl, Ingrid; Ostgaard, Nikolai; Chernouss, Sergey; Thompson, Barbara J.; Peticolas, Laura;

Analysis of ice-binding sites in fish type II antifreeze protein by quantum mechanics.

PubMed

Cheng, Yuhua; Yang, Zuoyin; Tan, Hongwei; Liu, Ruozhuang; Chen, Guangju; Jia, Zongchao

2002-10-01

Many organisms living in cold environments can survive subzero temperatures by producing antifreeze proteins (AFPs) or antifreeze glycoproteins. In this paper we investigate the ice-binding surface of type II AFP by quantum mechanical methods, which, to the best of our knowledge, represents the first time that molecular orbital computational approaches have been applied to AFPs. Molecular mechanical approaches, including molecular docking, energy minimization, and molecular dynamics simulation, were used to obtain optimal systems for subsequent quantum mechanical analysis. We selected 17 surface patches covering the entire surface of the type II AFP and evaluated the interaction energy between each of these patches and two different ice planes using semi-empirical quantum mechanical methods. We have demonstrated the weak orbital overlay phenomenon and the change of bond orders in ice. These results consistently indicate that a surface patch containing 19 residues (K37, L38, Y20, E22, Y21, I19, L57, T56, F53, M127, T128, F129, R17, C7, N6, P5, G10, Q1, and W11) is the most favorable ice-binding site for both a regular ice plane and an ice plane where water O atoms are randomly positioned. Furthermore, for the first time the computation results provide new insights into the weakening of the ice lattice upon AFP binding, which may well be a primary factor leading to AFP-induced ice growth inhibition.

Analysis of ice-binding sites in fish type II antifreeze protein by quantum mechanics.

PubMed Central

Cheng, Yuhua; Yang, Zuoyin; Tan, Hongwei; Liu, Ruozhuang; Chen, Guangju; Jia, Zongchao

2002-01-01

Many organisms living in cold environments can survive subzero temperatures by producing antifreeze proteins (AFPs) or antifreeze glycoproteins. In this paper we investigate the ice-binding surface of type II AFP by quantum mechanical methods, which, to the best of our knowledge, represents the first time that molecular orbital computational approaches have been applied to AFPs. Molecular mechanical approaches, including molecular docking, energy minimization, and molecular dynamics simulation, were used to obtain optimal systems for subsequent quantum mechanical analysis. We selected 17 surface patches covering the entire surface of the type II AFP and evaluated the interaction energy between each of these patches and two different ice planes using semi-empirical quantum mechanical methods. We have demonstrated the weak orbital overlay phenomenon and the change of bond orders in ice. These results consistently indicate that a surface patch containing 19 residues (K37, L38, Y20, E22, Y21, I19, L57, T56, F53, M127, T128, F129, R17, C7, N6, P5, G10, Q1, and W11) is the most favorable ice-binding site for both a regular ice plane and an ice plane where water O atoms are randomly positioned. Furthermore, for the first time the computation results provide new insights into the weakening of the ice lattice upon AFP binding, which may well be a primary factor leading to AFP-induced ice growth inhibition. PMID:12324437

Magnetic resonance diffusion and relaxation characterization of water in the unfrozen vein network in polycrystalline ice and its response to microbial metabolic products

NASA Astrophysics Data System (ADS)

Brown, Jennifer R.; Brox, Timothy I.; Vogt, Sarah J.; Seymour, Joseph D.; Skidmore, Mark L.; Codd, Sarah L.

2012-12-01

Polycrystalline ice, as found in glaciers and the ice sheets of Antarctica, is a low porosity porous media consisting of a complicated and dynamic pore structure of liquid-filled intercrystalline veins within a solid ice matrix. In this work, Nuclear Magnetic Resonance measurements of relaxation rates and molecular diffusion, useful for probing pore structure and transport dynamics in porous systems, were used to physically characterize the unfrozen vein network structure in ice and its response to the presence of metabolic products produced by V3519-10, a cold tolerant microorganism isolated from the Vostok ice core. Recent research has found microorganisms that can remain viable and even metabolically active within icy environments at sub-zero temperatures. One potential mechanism of survival for V3519-10 is secretion of an extracellular ice binding protein that binds to the prism face of ice crystals and inhibits ice recrystallization, a coarsening process resulting in crystal growth with ice aging. Understanding the impact of ice binding activity on the bulk vein network structure in ice is important to modeling of frozen geophysical systems and in development of ice interacting proteins for biotechnology applications, such as cryopreservation of cell lines, and manufacturing processes in food sciences. Here, we present the first observations of recrystallization inhibition in low porosity ice containing V3519-10 extracellular protein extract as measured with Nuclear Magnetic Resonance and Magnetic Resonance Imaging.

Identification of Plant Ice-binding Proteins Through Assessment of Ice-recrystallization Inhibition and Isolation Using Ice-affinity Purification.

PubMed

Bredow, Melissa; Tomalty, Heather E; Walker, Virginia K

2017-05-05

Ice-binding proteins (IBPs) belong to a family of stress-induced proteins that are synthesized by certain organisms exposed to subzero temperatures. In plants, freeze damage occurs when extracellular ice crystals grow, resulting in the rupture of plasma membranes and possible cell death. Adsorption of IBPs to ice crystals restricts further growth by a process known as ice-recrystallization inhibition (IRI), thereby reducing cellular damage. IBPs also demonstrate the ability to depress the freezing point of a solution below the equilibrium melting point, a property known as thermal hysteresis (TH) activity. These protective properties have raised interest in the identification of novel IBPs due to their potential use in industrial, medical and agricultural applications. This paper describes the identification of plant IBPs through 1) the induction and extraction of IBPs in plant tissue, 2) the screening of extracts for IRI activity, and 3) the isolation and purification of IBPs. Following the induction of IBPs by low temperature exposure, extracts are tested for IRI activity using a 'splat assay', which allows the observation of ice crystal growth using a standard light microscope. This assay requires a low protein concentration and generates results that are quickly obtained and easily interpreted, providing an initial screen for ice binding activity. IBPs can then be isolated from contaminating proteins by utilizing the property of IBPs to adsorb to ice, through a technique called 'ice-affinity purification'. Using cell lysates collected from plant extracts, an ice hemisphere can be slowly grown on a brass probe. This incorporates IBPs into the crystalline structure of the polycrystalline ice. Requiring no a priori biochemical or structural knowledge of the IBP, this method allows for recovery of active protein. Ice-purified protein fractions can be used for downstream applications including the identification of peptide sequences by mass spectrometry and the biochemical analysis of native proteins.

Hydro-thermal processes and thermal offsets of peat soils in the active layer in an alpine permafrost region, NE Qinghai-Tibet plateau

NASA Astrophysics Data System (ADS)

Wang, Qingfeng; Jin, Huijun; Zhang, Tingjun; Cao, Bin; Peng, Xiaoqing; Wang, Kang; Xiao, Xiongxin; Guo, Hong; Mu, Cuicui; Li, Lili

2017-09-01

Observation data of the hydrothermal processes in the active layer are vital for the verification of permafrost formation and evolution, eco-hydrology, ground-atmosphere interactions, and climate models at various time and spatial scales. Based on measurements of ground temperatures in boreholes, of temperatures and moisture contents of soils in the active layer, and of the mean annual air temperatures at the Qilian, Yeniugou and Tuole meteorological stations in the upper Heihe River Basin (UHRB) and the adjacent areas, a series of observations were made concerning changes in the lower limit of permafrost (LLP) and the related hydrothermal dynamics of soils in the active layer. Because of the thermal diode effect of peat soils, the LLP (at 3600 m) was lower on the northern slope of the Eboling Mountains at the eastern branch of the UHRB than that (at 3650-3700 m) on the alluvial plain at the western branch of the UHRB. The mean temperature of soils at depths of 5 to 77 cm in the active layer on peatlands was higher during periods with subzero temperatures and lower during periods with above-zero temperatures in the vicinity of the LLP on the northern slope of the Eboling Mountains than those at the LLP at the western branch of the UHRB. The thawing and downward freezing rates of soils in the active layer near the LLP on the northern slope of the Eboling Mountains were 0.2 and 1.6 times those found at the LLP at the western branch of the UHRB. From early May to late August, the soil water contents at the depths of 20 to 60 cm in the active layer near the LLP on the northern slope of the Eboling Mountains were significantly lower than those found at the LLP at the western branch of the UHRB. The annual ranges of soil temperatures (ARSTs), mean annual soil temperatures (MASTs) in the active layer on peatlands, and the mean annual ground temperature (MAGT) at a depth of 14 m of the underlying permafrost were all significantly lower near the LLP on the northern slope of the Eboling Mountains. Moreover, the thermophysical properties of peat soils and high moisture contents in the active layer on peatlands resulted in the lower soil temperatures in the active layer close to the LLP on the northern slope of the Eboling Mountains than those found at the LLP at the western branch of the UHRB in the warm season, especially at the deeper depths (20-77 cm). They also resulted in the smaller freezing index (FI) and thawing index (TI) and larger FI/TI ratios of soils at the depths of 5 to 77 cm in the active layer near the LLP on the northern slope of the Eboling Mountains. In short, peatlands have unique thermophysical properties for reducing heat absorption in the warm season and for limiting heat release in the cold season as well. However, the permafrost zone has shrunk by 10-20 km along the major highways at the western branch of the UHRB since 1985, and a medium-scale retrogressive slump has occurred on the peatlands on the northern slope of the Eboling Mountains in recent decades. The results can provide basic data for further studies of the hydrological functions of different landscapes in alpine permafrost regions. Such studies can also enable evaluations and forecasts the hydrological impacts of changing frozen ground in the UHRB and of other alpine mountain regions in West China.

The effect of volcanic eruptions on the chemistry of surface waters: The 1991 and 2000 eruptions of Mt. Hekla, Iceland

NASA Astrophysics Data System (ADS)

Flaathen, Therese K.; Gislason, Sigurdur R.

2007-08-01

The Mt. Hekla eruptions in 1991 and 2000 have provided a unique opportunity to study the local environmental effects of high latitude volcanic eruptions in the middle of winter. Both eruptions started around sunset at sub-zero temperatures. In order to define better these effects we studied the chemistry of surface waters in the vicinity of the volcano. Additionally, we describe and predict the environmental consequences of these volcanic eruptions on the chemistry of surface waters on land and in the ocean. Several dissolved elements in the polluted snow melt from the 2000 eruption (Cl, F, Al, Fe, Mn, As, Cd, Pb, Zn, and U) exceeded the limits for water intended for human consumption. The volcanic ash, the primary minerals and secondary mineral phases that commonly form in the weathering environment of Iceland were undersaturated in the polluted snow melts with the exception of fluorite, barite, goethite and amorphous FeOOH. These minerals can constrain the maximum initial concentration of the respective dissolved constituents in the meltwaters. It took few days after the first rainfall on the volcanic ash to flush out the readily soluble constituents in the vicinity of the headwaters of the Ytri-Rangá River. The polluted river waters were oversaturated with respect to several secondary minerals, resulting in precipitation of amorphous Al hydroxide and FeOOH and further, scavenging of some trace elements on the Al and Fe surfaces. Dissolved Al and F were the main contaminants in the Ytri-Rangá river water. Previous studies have shown that combined Al-F toxicity is directly related to the predominance of specific Al-F species in solution. Model calculations for mixing of a Hekla-type volcanic cloud with 4 surface water end-members shows Al-F species to be most important in rain and dilute river waters. This makes Al and F phyto-available but diminishes the concentration of the Al 3+ species, the most toxic Al species. Mixing with high alkalinity river waters or seawater results in the domination of non toxic Al(OH) 4- species at dilutions greater than 800, thus hindering Al toxicity and bioavailability. This study indicates that H 2SO 4 contamination from volcanic eruptions is time and place dependent. Volcanic eruptions that take place during winter at high latitudes result in relatively high global sulfur contamination and relatively low local sulfur contamination due to the low oxidation rate of SO 2 into H 2SO 4 because of the low solar radiation.

Diversity and cold adaptation of microorganisms isolated from the Schirmacher Oasis, Antarctica

NASA Astrophysics Data System (ADS)

Mojib, Nazia; Bej, Asim K.; Hoover, Richard

2008-08-01

We have investigated the feasibility of the PCR amplification of the 16S rRNA genes from eubacteria and Archea on samples collected on Whatman FTA filters from Schirmacher Oasis for the study of culture-independent analysis of the microbial diversity. Both conventional PCR and real-time TaqmaTM PCR successfully amplified the targeted genes. A number of diverse groups of psychrotolerant microorganisms with various pigments have been isolated when cultured on agar medium. 16S rRNA gene analysis of these isolates helped us to identify closest taxonomic genus Pseudomonas, Frigoribacterium, Arthrobacter, Flavobacterium, and Janthinobacterium. It is possible that the pigments play protective role from solar UV radiation, which is prevalent in Antarctic continent especially during Austral summer months. Study of the expression of cold adaptive protein CapB and ice-binding protein IBP using western blots showed positive detection of both or either of these proteins in 6 out of 8 isolates. Since the CapB and IBP protein structure greatly varies in microorganisms, it is possible that the 2 isolates with negative results could have a different class of these proteins. The expression of the CapB and the IBP in these isolates suggest that these proteins are essential for the survival in the Antarctic cold and subzero temperatures and protect themselves from freeze-damage. The current study provided sufficient data to further investigate the rich and diverse biota of psychrotolerant extremophiles in the Antarctic Schirmacher Oasis using both culture-independent and culture-based approaches; and understand the mechanisms of cold tolerance.

Additional freeze hardiness in wheat acquired by exposure to -3 degreesC is associated with extensive physiological, morphological, and molecular changes.

PubMed

Herman, Eliot M; Rotter, Kelsi; Premakumar, Ramaswamy; Elwinger, G; Bae, Hanhong; Bae, Rino; Ehler-King, Linda; Chen, Sixue; Livingston, David P

2006-01-01

Cold-acclimated plants acquire an additional 3-5 degrees C increase in freezing tolerance when exposed to -3 degrees C for 12-18 h before a freezing test (LT50) is applied. The -3 degrees C treatment replicates soil freezing that can occur in the days or weeks leading to overwintering by freezing-tolerant plants. This additional freezing tolerance is called subzero acclimation (SZA) to differentiate it from cold acclimation (CA) that is acquired at above-freezing temperatures. Using wheat as a model, results have been obtained indicating that SZA is accompanied by changes in physiology, cellular structure, the transcriptome, and the proteome. Using a variety of assays, including DNA arrays, reverse transcription-polymerase chain reaction (RT-PCR), 2D gels with mass spectroscopic identification of proteins, and electron microscopy, changes were observed to occur as a consequence of SZA and the acquisition of added freezing tolerance. In contrast to CA, SZA induced the movement of intracellular water to the extracellular space. Many unknown and stress-related genes were upregulated by SZA including some with obvious roles in SZA. Many genes related to photosynthesis and plastids were downregulated. Changes resulting from SZA often appeared to be a loss of rather than an appearance of new proteins. From a cytological perspective, SZA resulted in alterations of organelle structure including the Golgi. The results indicate that the enhanced freezing tolerance of SZA is correlated with a wide diversity of changes, indicating that the additional freezing tolerance is the result of complex biological processes.

Evolution of Microstructure in Brazed Joints of Austenitic-Martensitic Stainless Steel with Pure Silver Obtained with Ag-27Cu-5Sn Brazing Filler Material

NASA Astrophysics Data System (ADS)

Gangadharan, S.; Sivakumar, D.; Venkateswaran, T.; Kulkarni, Kaustubh

2016-12-01

Brazing of an austenitic-martensitic stainless steel (AMSS) with pure silver was carried out at 1053 K, 1073 K, and 1093 K (780 °C, 800 °C, and 820 °C) with Ag-27Cu-5Sn (wt pct) as brazing filler material (BFM). Wettability of the liquid BFM over base AMSS surface was found to be poor. Application of nickel coating to the steel was observed to enhance the wettability and to enable the formation of a good bond between BFM and the steel. The mechanism responsible for enhanced metallurgical bonding of the BFM with AMSS in the presence of nickel coating was explained based on diffusional interactions and uphill diffusion of iron, chromium and nickel observed in the brazed microstructure. Good diffusion-assisted zone was observed to form on silver side at all three temperatures. Four phases were encountered within the joint including silver solid solution, copper solid solution, Cu3Sn intermetallic and Ni-Fe solid solution. The Cu3Sn intermetallic was present in small amounts in the joints brazed at 1053 K and 1073 K (780 °C and 800 °C). The joint formed at 1093 K (820 °C) exhibited the absence of Cu3Sn, fewer defects and larger diffusion-assisted zone. Hardness of base AMSS was found to reduce during brazing due to austenite reversion and post-brazing sub-zero treatment for 2.5 hours was found suitable to recover the hardness.

Theoretical study of interaction of winter flounder antifreeze protein with ice

PubMed Central

Jorov, Alexander; Zhorov, Boris S.; Yang, Daniel S.C.

2004-01-01

Antifreeze proteins (AFPs) are synthesized by various organisms to enable their cells to survive subzero environment. These proteins bind to small ice crystals and inhibit their growth, which if left uncontrolled would be fatal to cells. The crystal structures of a number of AFPs have been determined; however, crystallographic analysis of AFP–ice complex is nearly impossible. Molecular modeling studies of AFPs’ interaction with ice surface is therefore invaluable. Early models of AFP–ice interaction suggested H-bond as the primary driving force behind such interaction. Recent experimental evidence, however, suggested that hydrophobic interactions could be the main contributor to AFP–ice association. All computational studies published to date were carried out to verify the H-bond model, and no works attempting to verify the hydrophobic interaction model have been published. In this work, we Monte Carlo–minimized complexes of several AFPs with ice taking into account nonbonded interactions, H-bonds, and the hydration potential for proteins. Parameters of the hydration potential for ice were developed with the assumption that the free energy of the water–ice association should be close to zero at equilibrium melting temperature. Our calculations demonstrate that desolvation of hydrophobic groups in the AFPs upon their binding to the grooves at the ice surface is indeed the major stabilizing contributor to the free energy of AFP–ice binding. This study is consistent with available structural and mutation data on AFPs. In particular, it explains the paradoxical finding that substitution of Thr residues with Val does not affect the potency of winter flounder AFP whereas substitution with Ser abolished its antifreeze activity. PMID:15152087

Anti-apoptotic response during anoxia and recovery in a freeze-tolerant wood frog (Rana sylvatica)

PubMed Central

Gerber, Victoria E.M.; Wijenayake, Sanoji

2016-01-01

The common wood frog, Rana sylvatica, utilizes freeze tolerance as a means of winter survival. Concealed beneath a layer of leaf litter and blanketed by snow, these frogs withstand subzero temperatures by allowing approximately 65–70% of total body water to freeze. Freezing is generally considered to be an ischemic event in which the blood oxygen supply is impeded and may lead to low levels of ATP production and exposure to oxidative stress. Therefore, it is as important to selectively upregulate cytoprotective mechanisms such as the heat shock protein (HSP) response and expression of antioxidants as it is to shut down majority of ATP consuming processes in the cell. The objective of this study was to investigate another probable cytoprotective mechanism, anti-apoptosis during oxygen deprivation and recovery in the anoxia tolerant wood frog. In particular, relative protein expression levels of two important apoptotic regulator proteins, Bax and p-p53 (S46), and five anti-apoptotic/pro-survival proteins, Bcl-2, p-Bcl-2 (S70), Bcl-xL, x-IAP, and c-IAP in response to normoxic, 24 Hr anoxic exposure, and 4 Hr recovery stages were assessed in the liver and skeletal muscle using western immunoblotting. The results suggest a tissue-specific regulation of the anti-apoptotic pathway in the wood frog, where both liver and skeletal muscle shows an overall decrease in apoptosis and an increase in cell survival. This type of cytoprotective mechanism could be aimed at preserving the existing cellular components during long-term anoxia and oxygen recovery phases in the wood frog. PMID:27042393

Biophysical characterization of the Lactobacillus delbrueckii subsp. bulgaricus membrane during cold and osmotic stress and its relevance for cryopreservation.

PubMed

Meneghel, Julie; Passot, Stéphanie; Dupont, Sébastien; Fonseca, Fernanda

2017-02-01

Freezing lactic acid bacteria often leads to cell death and loss of technological properties. Our objective was to provide an in-depth characterization of the biophysical properties of the Lactobacillus delbrueckii subsp. bulgaricus membrane in relation to its freeze resistance. Freezing was represented as a combination of cold and osmotic stress. This work investigated the relative incidence of increasing sucrose concentrations coupled or not with subzero temperatures without ice nucleation on the biological and biophysical responses of two strains with different membrane fatty acid compositions and freeze resistances. Following exposure of bacterial cells to the highest sucrose concentration, the sensitive strain exhibited a survival rate of less than 10 % and 5 h of acidifying activity loss. Similar biological activity losses were observed upon freeze-thawing and after osmotic treatment for each strain thus highlighting osmotic stress as the main source of cryoinjury. The direct measurement of membrane fluidity by fluorescence anisotropy was linked to membrane lipid organization characterized by FTIR spectroscopy. Both approaches made it possible to investigate the specific contributions of the membrane core and the bilayer external surface to cell degradation caused by cold and osmotic stress. Cold-induced membrane rigidification had no significant implication on bacterial freeze-thaw resistance. Interactions between extracellular sucrose and membrane phospholipid headgroups under osmotic stress were also observed. Such interactions were more evident in the sensitive strain and when increasing sucrose concentration, thus suggesting membrane permeabilization. The relevance of biophysical properties for elucidating mechanisms of cryoinjury and cryoprotection is discussed.

Preliminary results from a microvolume, dynamically heated analytical column for preconcentration and separation of simple gases prior to stable isotopic analysis

NASA Astrophysics Data System (ADS)

Panetta, Robert James; Seed, Mike

2016-04-01

Stable isotope applications that call for preconcentration (i.e., greenhouse gas measurements, small carbonate samples, etc.) universally call for cryogenic fluids such as liquid nitrogen, dry ice slurries, or expensive external recirculation chillers. This adds significant complexity, first and foremost in the requirements to store and handle such dangerous materials. A second layer of complexity is the instrument itself - with mechanisms to physically move either coolant around the trap, or move a trap in or out of the coolant. Not to mention design requirements for hardware that can safely isolate the fluid from other sensitive areas. In an effort to simplify the isotopic analysis of gases requiring preconcentration, we have developed a new separation technology, UltiTrapTM (patent pending), which leverage's the proprietary Advanced Purge & Trap (APT) Technology employed in elemental analysers from Elementar Analysensysteme GmbH products. UltiTrapTM has been specially developed as a micro volume, dynamically heated GC separation column. The introduction of solid-state cooling technology enables sub-zero temperatures without cryogenics or refrigerants, eliminates all moving parts, and increases analytical longevity due to no boiling losses of coolant . This new technology makes it possible for the system to be deployed as both a focussing device and as a gas separation device. Initial data on synthetic gas mixtures (CO2/CH4/N2O in air), and real-world applications including long-term room air and a comparison between carbonated waters of different origins show excellent agreement with previous technologies.

Long-term variability of dust events in Iceland (1949-2011)

NASA Astrophysics Data System (ADS)

Dagsson-Waldhauserova, P.; Arnalds, O.; Olafsson, H.

2014-12-01

The long-term frequency of atmospheric dust observations was investigated for the southern part of Iceland and interpreted together with earlier results obtained from northeastern (NE) Iceland (Dagsson-Waldhauserova et al., 2013). In total, over 34 dust days per year on average occurred in Iceland based on conventionally used synoptic codes for dust observations. However, frequent volcanic eruptions, with the re-suspension of volcanic materials and dust haze, increased the number of dust events fourfold (135 dust days annually). The position of the Icelandic Low determined whether dust events occurred in the NE (16.4 dust days annually) or in the southern (S) part of Iceland (about 18 dust days annually). The decade with the most frequent dust days in S Iceland was the 1960s, but the 2000s in NE Iceland. A total of 32 severe dust storms (visibility < 500 m) were observed in Iceland with the highest frequency of events during the 2000s in S Iceland. The Arctic dust events (NE Iceland) were typically warm, occurring during summer/autumn (May-September) and during mild southwesterly winds, while the subarctic dust events (S Iceland) were mainly cold, occurring during winter/spring (March-May) and during strong northeasterly winds. About half of the dust events in S Iceland occurred in winter or at sub-zero temperatures. A good correlation was found between particulate matter (PM10) concentrations and visibility during dust observations at the stations Vík and Stórhöfði. This study shows that Iceland is among the dustiest areas of the world and that dust is emitted year-round.

Evidence for mechanical and chemical alteration of iron-nickel meteorites on Mars: Process insights for Meridiani Planum

USGS Publications Warehouse

Ashley, James W.; Golombek, M.P.; Christensen, P.R.; Squyres, S. W.; McCoy, T.J.; Schroder, C.; Fleischer, I.; Johnson, J. R.; Herkenhoff, K. E.; Parker, T.J.

2011-01-01

The weathering of meteorites found on Mars involves chemical and physical processes that can provide clues to climate conditions at the location of their discovery. Beginning on sol 1961, the Opportunity rover encountered three large iron meteorites within a few hundred meters of each other. In order of discovery, these rocks have been assigned the unofficial names Block Island, Shelter Island, and Mackinac Island. Each rock presents a unique but complimentary set of features that increase our understanding of weathering processes at Meridiani Planum. Significant morphologic characteristics interpretable as weathering features include (1) a large pit in Block Island, lined with delicate iron protrusions suggestive of inclusion removal by corrosive interaction; (2) differentially eroded kamacite and taenite lamellae in Block Island and Shelter Island, providing relative timing through crosscutting relationships with deposition of (3) an iron oxide-rich dark coating; (4) regmaglypted surfaces testifying to regions of minimal surface modification, with other regions in the same meteorites exhibiting (5) large-scale, cavernous weathering (in Shelter Island and Mackinac Island). We conclude that the current size of the rocks is approximate to their original postfall contours. Their morphology thus likely results from a combination of atmospheric interaction and postfall weathering effects. Among our specific findings is evidence supporting (1) at least one possible episode of aqueous acidic exposure for Block Island; (2) ripple migration over portions of the meteorites; (3) a minimum of two separate episodes of wind abrasion; alternating with (4) at least one episode of coating-forming chemical alteration, most likely at subzero temperatures. Copyright 2011 by the American Geophysical Union.

Implications of subzero metabolic activity on long-term microbial survival in terrestrial and extraterrestrial permafrost.

PubMed

Amato, Pierre; Doyle, Shawn M; Battista, John R; Christner, Brent C

2010-10-01

The survival of microorganisms over extended time frames in frozen subsurface environments may be limited by chemical (i.e., via hydrolysis and oxidation) and ionizing radiation-induced damage to chromosomal DNA. In an effort to improve estimates for the survival of bacteria in icy terrestrial and extraterrestrial environments, we determined rates of macromolecular synthesis at temperatures down to -15°C in bacteria isolated from Siberian permafrost (Psychrobacter cryohalolentis K5 and P. arcticus 273-4) and the sensitivity of P. cryohalolentis to ionizing radiation. Based on experiments conducted over ≈400 days at -15°C, the rates of protein and DNA synthesis in P. cryohalolentis were <1 to 16 proteins cell(-1) d(-1) and 83 to 150 base pairs (bp) cell(-1) d(-1), respectively; P. arcticus synthesized DNA at rates of 20 to 1625 bp cell(-1) d(-1) at -15°C under the conditions tested. The dose of ionizing radiation at which 37% of the cells survive (D(37)) of frozen suspensions of P. cryohalolentis was 136 Gy, which was ∼2-fold higher (71 Gy) than identical samples exposed as liquid suspensions. Laboratory measurements of [(3)H]thymidine incorporation demonstrate the physiological potential for DNA metabolism at -15°C and suggest a sufficient activity is possible to offset chromosomal damage incurred in near-subsurface terrestrial and martian permafrost. Thus, our data imply that the longevity of microorganisms actively metabolizing within permafrost environments is not constrained by chromosomal DNA damage resulting from ionizing radiation or entropic degradation over geological time.

Bioreactor Landfill Research and Demonstration Project Northern Oaks Landfill, Harrison, MI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Xiando; Voice, Thomas; and Hashsham, Syed A.

2006-08-29

A bioreactor landfill cell with 1.2-acre footprint was constructed, filled, operated, and monitored at Northern Oaks Recycling and Disposal Facility (NORDF) at Harrison, MI. With a filled volume of 74,239 cubic yards, the cell contained approximately 35,317 tons of municipal solid waste (MSW) and 20,777 tons of cover soil. It was laid on the slope of an existing cell but separated by a geosynthetic membrane liner. After the cell reached a design height of 60 feet, it was covered with a geosynthetic membrane cap. A three-dimensional monitoring system to collect data at 48 different locations was designed and installed duringmore » the construction phase of the bioreactor cell. Each location had a cluster of monitoring devices consisting of a probe to monitor moisture and temperature, a leachate collection basin, and a gas sampling port. An increase in moisture content of the MSW in the bioreactor cell was achieved by pumping leachate collected on-site from various other cells, as well as recirculation of leachate from the bioreactor landfill cell itself. Three types of leachate injection systems were evaluated in this bioreactor cell for their efficacy to distribute pumped leachate uniformly: a leachate injection pipe buried in a 6-ft wide horizontal stone mound, a 15-ft wide geocomposite drainage layer, and a 60-ft wide geocomposite drainage layer. All leachate injection systems were installed on top of the compacted waste surface. The distribution of water and resulting MSW moisture content throughout the bioreactor cell was found to be similar for the three designs. Water coming into and leaving the cell (leachate pumped in, precipitation, snow, evaporation, and collected leachate) was monitored in order to carry out a water balance. Using a leachate injection rate of 26 – 30 gal/yard3, the average moisture content increased from 25% to 35% (wet based) over the period of this study. One of the key aspects of this bioreactor landfill study was to evaluate bioreactor start up and performance in locations with colder climate. For lifts filled during the summer months, methane generation started within three months after completion of the lift. For lifts filled in winter months, very little methane production occurred even eight months after filling. The temperature data indicated that subzero or slightly above zero (oC) temperatures persisted for unusually long periods (more than six months) in the lifts filled during winter months. This was likely due to the high thermal insulation capability of the MSW and the low level of biological activity during start up. This observation indicates that bioreactor landfills located in cold climate and filled during winter months may require mechanisms to increase temperature and initiate biodegradation. Thus, besides moisture, temperature may be the next important factor controlling the biological decomposition in anaerobic bioreactor landfills. Spatial and temporal characterization of leachate samples indicated the presence of low levels of commonly used volatile organic compounds (including acetone, methyl ethyl ketone, methyl isobutyl ketone, and toluene) and metals (including arsenic, chromium, and zinc). Changes and leachate and gaseous sample characteristics correlated with enhanced biological activity and increase in temperature. Continued monitoring of this bioreactor landfill cell is expected to yield critical data needed for start up, design, and operation of this emerging process.« less

Practical water production from desert air.

PubMed

Fathieh, Farhad; Kalmutzki, Markus J; Kapustin, Eugene A; Waller, Peter J; Yang, Jingjing; Yaghi, Omar M

2018-06-01

Energy-efficient production of water from desert air has not been developed. A proof-of-concept device for harvesting water at low relative humidity was reported; however, it used external cooling and was not desert-tested. We report a laboratory-to-desert experiment where a prototype using up to 1.2 kg of metal-organic framework (MOF)-801 was tested in the laboratory and later in the desert of Arizona, USA. It produced 100 g of water per kilogram of MOF-801 per day-and-night cycle, using only natural cooling and ambient sunlight as a source of energy. We also report an aluminum-based MOF-303, which delivers more than twice the amount of water. The desert experiment uncovered key parameters pertaining to the energy, material, and air requirements for efficient production of water from desert air, even at a subzero dew point.

Ice barriers promote supercooling and prevent frost injury in reproductive buds, flowers and fruits of alpine dwarf shrubs throughout the summer.

PubMed

Kuprian, Edith; Briceño, Verónica F; Wagner, Johanna; Neuner, Gilbert

2014-10-01

Over-wintering reproductive buds of many woody plants survive frost by supercooling. The bud tissues are isolated from acropetally advancing ice by the presence of ice barriers that restrict ice growth. Plants living in alpine environments also face the risk of ice formation in summer months. Little knowledge exists, how reproductive structures of woody alpine plants are protected from frost injury during episodic summer frosts. In order to address this question, frost resistance of three common dwarf shrubs, Calluna vulgaris , Empetrum hermaphroditum and Loiseleuria procumbens was measured and ice formation and propagation were monitored in twigs bearing reproductive shoots during various stages of reproductive development (bud, anthesis, and fruit) throughout the alpine summer. Results indicated that, in the investigated species, ice barriers were present at all reproductive stages, isolating the reproductive shoots from ice advancing from the subtending vegetative shoot. Additionally, in the reproductive stems ice nucleating agents that are active at warm, sub-zero temperatures, were absent. The ice barriers were 100% effective, with the exception of L. procumbens , where in 13% of the total observations, the ice barrier failed. The ice barriers were localized at the base of the pedicel, at the anatomical junction of the vegetative and reproductive shoot. There, structural aspects of the tissue impede or prevent ice from advancing from the frozen stem into the pedicel of the reproductive shoot. Under the experimental conditions used in this study, ice nucleation initially occurred in the stem of the vegetative shoot at species-specific mean temperatures in the range of -4.7 to -5.8 °C. Reproductive shoots, however, remained supercooled and ice free down to a range of -7.2 to -18.2 °C or even below -22 °C, the lowest temperature applied in the study. This level of supercooling is sufficient to prevent freezing of reproductive structures at the lowest air temperature occurring at the altitude of the upper distribution boundary of the natural habitat of the investigated species which is between -8 and -10 °C in summer. Frost resistance assays indicated that reproductive shoots are much less frost resistant than vegetative stems, and in contrast to vegetative shoots, are not ice tolerant. Supercooling of reproductive shoots in alpine, woody plant species is an effective mechanism that protects developing offspring from potential frost damage resulting from episodic summer freezing events.

Ice barriers promote supercooling and prevent frost injury in reproductive buds, flowers and fruits of alpine dwarf shrubs throughout the summer☆

PubMed Central

Kuprian, Edith; Briceño, Verónica F.; Wagner, Johanna; Neuner, Gilbert

2014-01-01

Over-wintering reproductive buds of many woody plants survive frost by supercooling. The bud tissues are isolated from acropetally advancing ice by the presence of ice barriers that restrict ice growth. Plants living in alpine environments also face the risk of ice formation in summer months. Little knowledge exists, how reproductive structures of woody alpine plants are protected from frost injury during episodic summer frosts. In order to address this question, frost resistance of three common dwarf shrubs, Calluna vulgaris, Empetrum hermaphroditum and Loiseleuria procumbens was measured and ice formation and propagation were monitored in twigs bearing reproductive shoots during various stages of reproductive development (bud, anthesis, and fruit) throughout the alpine summer. Results indicated that, in the investigated species, ice barriers were present at all reproductive stages, isolating the reproductive shoots from ice advancing from the subtending vegetative shoot. Additionally, in the reproductive stems ice nucleating agents that are active at warm, sub-zero temperatures, were absent. The ice barriers were 100% effective, with the exception of L. procumbens, where in 13% of the total observations, the ice barrier failed. The ice barriers were localized at the base of the pedicel, at the anatomical junction of the vegetative and reproductive shoot. There, structural aspects of the tissue impede or prevent ice from advancing from the frozen stem into the pedicel of the reproductive shoot. Under the experimental conditions used in this study, ice nucleation initially occurred in the stem of the vegetative shoot at species-specific mean temperatures in the range of −4.7 to −5.8 °C. Reproductive shoots, however, remained supercooled and ice free down to a range of −7.2 to −18.2 °C or even below −22 °C, the lowest temperature applied in the study. This level of supercooling is sufficient to prevent freezing of reproductive structures at the lowest air temperature occurring at the altitude of the upper distribution boundary of the natural habitat of the investigated species which is between −8 and −10 °C in summer. Frost resistance assays indicated that reproductive shoots are much less frost resistant than vegetative stems, and in contrast to vegetative shoots, are not ice tolerant. Supercooling of reproductive shoots in alpine, woody plant species is an effective mechanism that protects developing offspring from potential frost damage resulting from episodic summer freezing events. PMID:25284910

Formation of Gas Traps in the Martian Soil and Implications for Methane Variability on Mars.

NASA Astrophysics Data System (ADS)

Pavlov, A.; Davis, J.; Redwing, E.; Trainer, M. G.; Johnson, C.

2017-12-01

Several independent groups have reported on the detection of methane in the Martian atmosphere. Mars Science Laboratory (MSL) methane observations display rapid increase of the atmospheric methane abundance from 1 ppb to 7 ppb levels followed by an abrupt disappearance suggest the possibility of small, local, near-surface sources of methane. Such sources may take the form of shallow subsurface cemented soil caps which can trap gases and are readily activated by either motion of the MSL rover itself, by impacts of small meteorites, or even annual climate oscillations. We have simulated the formation of such soil caps in the shallow subsurface Martian-like condition. We show that the initially uniform sample of icy soil (JSC-Mars-1A) with Mg perchlorate exhibit quick stratification on the scale of several cm under Martian pressures over the period of several days. Briny water migrates towards the top of the sample resulting in the enhanced abundance of perchlorates in the top few cm. As water evaporates and ice sublimates from the top of the sample, perchlorate remains in the top layer of soil causing soil cementation and formation of the cap. The observed caps were solid, ice-free and effectively shut off sublimation of ice from underneath the cap. We tested whether similar soil caps can trap various gases (including methane) in the shallow subsurface of Mars. We injected neon gas at the bottom of the soil sample and monitored neon gas permeability through the soil sample by measuring gas pressure differential above and below the soil sample. We found that a mixture of JSC-Mars-1A and 5% of Mg perchlorate produce gas impermeable soil cap capable of withstanding an excess of 5 mbars of neon under the cap at the soil temperatures +0.5 C - +9 C. The cap remained gas impermeable after subsequent cooling of the sample soil sample to the subzero temperatures. Gas permeability of the soil caps under various temperatures and atmospheric pressures will be reported. Our results suggest that the formation of cemented soil caps can be widespread phenomena on Mars in the areas of shallow permafrost and abundant perchlorates or RSL slopes. Potentially, soil caps can form gas pockets for trace species (like methane) which can be relatively easily disturbed causing abrupt changes in the atmospheric methane abundance detected by MSL's Curiosity rover.

Observed temporal hydrate-pingo alteration at pockmark G11, Nyegga, - an important climate-change signal?

NASA Astrophysics Data System (ADS)

Hovland, M. T.

2010-12-01

Complex pockmark G11 at Nyegga, occurs adjacent to the northern flank of the Storegga Slide, off mid-Norway. It is a 12 m deep and 200 - 250 m wide oval-shaped depression at ~750 m water depth. The crater-like depression contains at least six up to 4 m wide and 2 m high hydrate-pingoes in addition to large, rugged methane-derived carbonate rock ridges. Despite an ambient sub-zero water temperature (~ - 0.7 °C), the pockmark teems with life, ranging from primary producers, e.g., chemosynthetic bacteria to higher trophic animals, including filter-feeders, stalked crinoids, large pycnogonids, and various kinds of teleostei, mainly skate and eel pout. One of the circular, cylinder-shaped hydrate pingoes (‘Ice1’, Hovland and Svensen, 2006), was measured in 2004 to be about 1 m in diameter and 25 cm high. It was re-visited with ROV (remotely operated vehicle) in 2009 and was found to have slightly altered its shape and become slightly smaller. The features of the G11-pockmark, including bacterial mats, sampled gas hydrates, high biodiversity, and hydrate-pingoes documents that active fluid flow (seepage) occurs through the seafloor. Although the currently observed activity at G11 seems to be in a mode of slow, steady-state flux, e.g., ‘micro-seepage’, slightly warmer bottom water expected as a consequence of the global warming trend may induce a ‘galloping melting’ or dramatically increased seepage flux in the near future. During the last few years, there has been a trend of ocean bottom water warming along most of the 1500 km long western Norwegian coastline with up to 0.8°C above normal (www.imr.no). If this same trend also occurs at 750 m water depth at Nyegga, about 170 km west of the coastline, then there is a danger of escalating pingo-alteration at G11. Because of its easy access for research vessels and its well-documented near-surface features, G11/Nyegga represents an ideal location for the early-warning documentation of incipient hydrate destabilization in the North Atlantic ocean. Therefore, an initiative to instrument the area with auto-recording instruments will now be taken. - Hovland, M., Svensen, H., 2006. Submarine pingoes: Indicators of shallow gas hydrates in a pockmark at Nyegga, Norwegian Sea. Marine Geology, 228, 15-23. The figure illustrates hydrate-pingoes (dark ‘blobs’) located between up-turned carbonate blocks (C1 and C2) at G11, Nyegga (Hovland and Svensen, 2006).

Solution structures, dynamics, and ice growth inhibitory activity of peptide fragments derived from an antarctic yeast protein.

PubMed

Shah, Syed Hussinien H; Kar, Rajiv K; Asmawi, Azren A; Rahman, Mohd Basyaruddin A; Murad, Abdul Munir A; Mahadi, Nor M; Basri, Mahiran; Rahman, Raja Noor Zaliha A; Salleh, Abu B; Chatterjee, Subhrangsu; Tejo, Bimo A; Bhunia, Anirban

2012-01-01

Exotic functions of antifreeze proteins (AFP) and antifreeze glycopeptides (AFGP) have recently been attracted with much interest to develop them as commercial products. AFPs and AFGPs inhibit ice crystal growth by lowering the water freezing point without changing the water melting point. Our group isolated the Antarctic yeast Glaciozyma antarctica that expresses antifreeze protein to assist it in its survival mechanism at sub-zero temperatures. The protein is unique and novel, indicated by its low sequence homology compared to those of other AFPs. We explore the structure-function relationship of G. antarctica AFP using various approaches ranging from protein structure prediction, peptide design and antifreeze activity assays, nuclear magnetic resonance (NMR) studies and molecular dynamics simulation. The predicted secondary structure of G. antarctica AFP shows several α-helices, assumed to be responsible for its antifreeze activity. We designed several peptide fragments derived from the amino acid sequences of α-helical regions of the parent AFP and they also showed substantial antifreeze activities, below that of the original AFP. The relationship between peptide structure and activity was explored by NMR spectroscopy and molecular dynamics simulation. NMR results show that the antifreeze activity of the peptides correlates with their helicity and geometrical straightforwardness. Furthermore, molecular dynamics simulation also suggests that the activity of the designed peptides can be explained in terms of the structural rigidity/flexibility, i.e., the most active peptide demonstrates higher structural stability, lower flexibility than that of the other peptides with lower activities, and of lower rigidity. This report represents the first detailed report of downsizing a yeast AFP into its peptide fragments with measurable antifreeze activities.

Calcium interacts with antifreeze proteins and chitinase from cold-acclimated winter rye.

PubMed

Stressmann, Maja; Kitao, Satoshi; Griffith, Marilyn; Moresoli, Christine; Bravo, León A; Marangoni, Alejandro G

2004-05-01

During cold acclimation, winter rye (Secale cereale) plants accumulate pathogenesis-related proteins that are also antifreeze proteins (AFPs) because they adsorb onto ice and inhibit its growth. Although they promote winter survival in planta, these dual-function AFPs proteins lose activity when stored at subzero temperatures in vitro, so we examined their stability in solutions containing CaCl2, MgCl2, or NaCl. Antifreeze activity was unaffected by salts before freezing, but decreased after freezing and thawing in CaCl2 and was recovered by adding a chelator. Ca2+ enhanced chitinase activity 3- to 5-fold in unfrozen samples, although hydrolytic activity also decreased after freezing and thawing in CaCl2. Native PAGE, circular dichroism, and Trp fluorescence experiments showed that the AFPs partially unfold after freezing and thawing, but they fold more compactly or aggregate in CaCl2. Ruthenium red, which binds to Ca(2+)-binding sites, readily stained AFPs in the absence of Ca2+, but less stain was visible after freezing and thawing AFPs in CaCl2. We conclude that the structure of AFPs changes during freezing and thawing, creating new Ca(2+)-binding sites. Once Ca2+ binds to those sites, antifreeze activity, chitinase activity and ruthenium red binding are all inhibited. Because free Ca2+ concentrations are typically low in the apoplast, antifreeze activity is probably stable to freezing and thawing in planta. Ca2+ may regulate chitinase activity if concentrations are increased locally by release from pectin or interaction with Ca(2+)-binding proteins. Furthermore, antifreeze activity can be easily maintained in vitro by including a chelator during frozen storage.

Sub-zero cold tolerance of Spartina pectinata (prairie cordgrass) and Miscanthus × giganteus: candidate bioenergy crops for cool temperate climates

PubMed Central

Peixoto, Murilo de Melo; Lee, D. K.; Sage, Rowan F.

2015-01-01

Miscanthus × giganteus grown in cool temperate regions of North America and Europe can exhibit severe mortality in the year after planting, and poor frost tolerance of leaves. Spartina pectinata (prairie cordgrass), a productive C4 perennial grass native to North America, has been suggested as an alternative biofuel feedstock for colder regions; however, its cold tolerance relative to M. × giganteus is uncertain. Here, we compare the cold tolerance thresholds for winter-dormant rhizomes and spring/summer leaves of M. × giganteus and three accessions of S. pectinata. All genotypes were planted at a field site in Ontario, Canada. In November and February, the temperatures corresponding to 50% rhizome mortality (LT50) were near −24°C for S. pectinata and −4°C for M. × giganteus. In late April, the LT50 of rhizomes rose to −10°C for S. pectinata but remained near −4°C for M. × giganteus. Twenty percent of the M. × giganteus rhizomes collected in late April were dead while S. pectinata rhizomes showed no signs of winter injury. Photosynthesis and electrolyte leakage measurements in spring and summer demonstrate that S. pectinata leaves have greater frost tolerance in the field. For example, S. pectinata leaves remained viable above −9°C while the mortality threshold was near −5°C for M. × giganteus. These results indicate M. × giganteus will be unsuitable for production in continental interiors of cool-temperate climate zones unless freezing and frost tolerance are improved. By contrast, S. pectinata has the freezing and frost tolerance required for a higher-latitude bioenergy crop. PMID:25873680

Characterization of the Paleoenvironmental Evolution of the Mallik Area From Gas Geochemistry Data

NASA Astrophysics Data System (ADS)

Wiersberg, T.; Erzinger, J.

2007-12-01

During drilling of the JAPEX/JNOC/GCS et al. Mallik Gas Hydrate Production Research wells (NWT, Canada), up to 35 vol-% CH4 were found in drill mud gas at 106 m depth within the permafrost. The carbon isotope composition of CH4 implies that this gas is of microbial origin (δ13C from -75‰ to - 77‰ PDB). Surprisingly, noble gas data suggest that at least some of this gas could be trapped in gas hydrates, at a depth distinctly shallower than the predicted gas hydrate stability field. Although microbes are capable of some metabolic activities at subzero temperatures, it is unlikely that production of methane under permafrost conditions can account for that amount of natural gas at this depth. Therefore, we suggest that the formation of this gas must have occurred under non-permafrost conditions. Furthermore, this gas reservoir was sealed from mixing with thermogenic gas, migrating from depth, which could be identified at the base of the permafrost at approx. 620m depth (δ13C=-42.5‰). We interpret the observed features by partially thawing of existing permafrost at least down to 106 m depth during a period of warming where the area was covered by a lake or by the ocean through inundation of the shoreline. Once the lake was drained or the shoreline was uplifted, the surface became again exposed to air and permafrost again developed on top of the unfrozen ground. As the permafrost gradually advanced downward, the water below was pressurized due to freezing and expansion of the newly formed ice, leading to pressure conditions that stabilize gas hydrates.

Solution Structures, Dynamics, and Ice Growth Inhibitory Activity of Peptide Fragments Derived from an Antarctic Yeast Protein

PubMed Central

Asmawi, Azren A.; Rahman, Mohd Basyaruddin A.; Murad, Abdul Munir A.; Mahadi, Nor M.; Basri, Mahiran; Rahman, Raja Noor Zaliha A.; Salleh, Abu B.; Chatterjee, Subhrangsu; Tejo, Bimo A.; Bhunia, Anirban

2012-01-01

Exotic functions of antifreeze proteins (AFP) and antifreeze glycopeptides (AFGP) have recently been attracted with much interest to develop them as commercial products. AFPs and AFGPs inhibit ice crystal growth by lowering the water freezing point without changing the water melting point. Our group isolated the Antarctic yeast Glaciozyma antarctica that expresses antifreeze protein to assist it in its survival mechanism at sub-zero temperatures. The protein is unique and novel, indicated by its low sequence homology compared to those of other AFPs. We explore the structure-function relationship of G. antarctica AFP using various approaches ranging from protein structure prediction, peptide design and antifreeze activity assays, nuclear magnetic resonance (NMR) studies and molecular dynamics simulation. The predicted secondary structure of G. antarctica AFP shows several α-helices, assumed to be responsible for its antifreeze activity. We designed several peptide fragments derived from the amino acid sequences of α-helical regions of the parent AFP and they also showed substantial antifreeze activities, below that of the original AFP. The relationship between peptide structure and activity was explored by NMR spectroscopy and molecular dynamics simulation. NMR results show that the antifreeze activity of the peptides correlates with their helicity and geometrical straightforwardness. Furthermore, molecular dynamics simulation also suggests that the activity of the designed peptides can be explained in terms of the structural rigidity/flexibility, i.e., the most active peptide demonstrates higher structural stability, lower flexibility than that of the other peptides with lower activities, and of lower rigidity. This report represents the first detailed report of downsizing a yeast AFP into its peptide fragments with measurable antifreeze activities. PMID:23209600

Practical water production from desert air

PubMed Central

Kalmutzki, Markus J.; Kapustin, Eugene A.

2018-01-01

Energy-efficient production of water from desert air has not been developed. A proof-of-concept device for harvesting water at low relative humidity was reported; however, it used external cooling and was not desert-tested. We report a laboratory-to-desert experiment where a prototype using up to 1.2 kg of metal-organic framework (MOF)–801 was tested in the laboratory and later in the desert of Arizona, USA. It produced 100 g of water per kilogram of MOF-801 per day-and-night cycle, using only natural cooling and ambient sunlight as a source of energy. We also report an aluminum-based MOF-303, which delivers more than twice the amount of water. The desert experiment uncovered key parameters pertaining to the energy, material, and air requirements for efficient production of water from desert air, even at a subzero dew point. PMID:29888332

Ice-shell purification of ice-binding proteins.

PubMed

Marshall, Craig J; Basu, Koli; Davies, Peter L

2016-06-01

Ice-affinity purification is a simple and efficient method of purifying to homogeneity both natural and recombinant ice-binding proteins. The purification involves the incorporation of ice-binding proteins into slowly-growing ice and the exclusion of other proteins and solutes. In previous approaches, the ice was grown around a hollow brass finger through which coolant was circulated. We describe here an easily-constructed apparatus that employs ice affinity purification that not only shortens the time for purification from 1-2 days to 1-2 h, but also enhances yield and purity. In this apparatus, the surface area for the separation was increased by extracting the ice-binding proteins into an ice-shell formed inside a rotating round-bottom flask partially submerged in a sub-zero bath. In principle, any ice-binding compound can be recovered from liquid solution, and the method is readily scalable. Copyright © 2016 Elsevier Inc. All rights reserved.

Computer routines for probability distributions, random numbers, and related functions

USGS Publications Warehouse

Kirby, W.H.

1980-01-01

Use of previously codes and tested subroutines simplifies and speeds up program development and testing. This report presents routines that can be used to calculate various probability distributions and other functions of importance in statistical hydrology. The routines are designed as general-purpose Fortran subroutines and functions to be called from user-written main programs. The probability distributions provided include the beta, chisquare, gamma, Gaussian (normal), Pearson Type III (tables and approximation), and Weibull. Also provided are the distributions of the Grubbs-Beck outlier test, Kolmogorov 's and Smirnov 's D, Student 's t, noncentral t (approximate), and Snedecor F tests. Other mathematical functions include the Bessel function I (subzero), gamma and log-gamma functions, error functions and exponential integral. Auxiliary services include sorting and printer plotting. Random number generators for uniform and normal numbers are provided and may be used with some of the above routines to generate numbers from other distributions. (USGS)

Microbial diversity in European alpine permafrost and active layers.

PubMed

Frey, Beat; Rime, Thomas; Phillips, Marcia; Stierli, Beat; Hajdas, Irka; Widmer, Franco; Hartmann, Martin

2016-03-01

Permafrost represents a largely understudied genetic resource. Thawing of permafrost with global warming will not only promote microbial carbon turnover with direct feedback on greenhouse gases, but also unlock an unknown microbial diversity. Pioneering metagenomic efforts have shed light on the permafrost microbiome in polar regions, but temperate mountain permafrost is largely understudied. We applied a unique experimental design coupled to high-throughput sequencing of ribosomal markers to characterize the microbiota at the long-term alpine permafrost study site 'Muot-da-Barba-Peider' in eastern Switzerland with an approximate radiocarbon age of 12 000 years. Compared to the active layers, the permafrost community was more diverse and enriched with members of the superphylum Patescibacteria (OD1, TM7, GN02 and OP11). These understudied phyla with no cultured representatives proposedly feature small streamlined genomes with reduced metabolic capabilities, adaptations to anaerobic fermentative metabolisms and potential ectosymbiotic lifestyles. The permafrost microbiota was also enriched with yeasts and lichenized fungi known to harbour various structural and functional adaptation mechanisms to survive under extreme sub-zero conditions. These data yield an unprecedented view on microbial life in temperate mountain permafrost, which is increasingly important for understanding the biological dynamics of permafrost in order to anticipate potential ecological trajectories in a warming world. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Testing the Late Noachian Icy Highlands Model: Geological Observations, Processes and Origin of Fluvial and Lacustrine Features.

NASA Astrophysics Data System (ADS)

Head, James; Wordsworth, Robin; Forget, Francis; Madeleine, Jean-Baptiste; Halvey, Italy

2014-05-01

A new reconstruction of the Late Noachian Mars atmosphere and climate shows atmosphere-surface thermal coupling and an adiabatic cooling effect producing preferential distribution of snow and ice in the highlands. In this Late Noachian Icy Highlands (LNIH) scenario, snow and ice accumulate in the south circumpolar region and in the higher altitudes of the southern uplands, but the mean annual temperature is everywhere below freezing. How can the abundant evidence for water-related fluvial and lacustrine activity (valley networks, VN; open-basin lakes, OBL; closed-basin lakes; CBL) be reconciled with the icy highlands model? We investigate the nature of geologic processes operating in the icy highlands and use the Antarctic McMurdo Dry Valleys (MDV) as guidance in understanding and assessing how melting might be taking place. In the MDV, mean annual temperatures (MAT) are well below freezing. This results in a thick regional permafrost layer, the presence of an ice-table at shallow depths, and an overlying dry active layer. This configuration produces a perched aquifer and a horizontally stratified hydrologic system, where any melting results in local saturation of the dry active layer and channelized flow on top of the ice table. Top-down melting results in the dominance of lateral water transport, in contrast to temperate climates with vertical infiltration and transport to the groundwater table. Despite subzero MAT, MDV peak seasonal and peak daytime temperatures can exceed 273K and have a strong influence on the melting of available water ice. We present maps of the predicted distribution of LNIH snow and ice, compare these to the distribution of VN, OBL and CBL, and assess how top-down and bottom-up melting processes might explain the formation of these features in an otherwise cold and icy LN Mars. We assess the global near-surface water budget, analyze thickness estimates to distinguish areas of cold-based and wet-based glaciation, analyze the state of the ice cover and its susceptibility to melting and runoff, and describe top-down melting and fluvial channel formation processes in a LNIH environment. We find that: 1) episodic top-down melting of the LNIH is a robust mechanism to produce the observed fluvial and lacustrine features; 2) the characteristics and distribution of features in the Dorsa Argentea Formation are consistent with an extensive circum-polar ice cap during LNIH time; and 3) the nature of preserved LN impact craters is consistent with impact cratering processes in the LNIH environment. 393 words.

Nucleation via an unstable intermediate phase.

PubMed

Sear, Richard P

2009-08-21

The pathway for crystallization from dilute vapors and solutions is often observed to take a detour via a liquid or concentrated-solution phase. For example, in moist subzero air, droplets of liquid water form, which then freeze. In this example and in many others, an intermediate phase (here liquid water) is dramatically accelerating the kinetics of a phase transition between two other phases (water vapor and ice). Here we study this phenomenon via exact computer simulations of a simple lattice model. Surprisingly, we find that the rate of nucleation of the new equilibrium phase is actually fastest when the intermediate phase is slightly unstable in the bulk, i.e., has a slightly higher free energy than the phase we start in. Nucleation occurs at a concave part of the surface and microscopic amounts of the intermediate phase can form there even before the phase is stable in the bulk. As the nucleus of the equilibrium phase is microscopic, this allows nucleation to occur effectively in the intermediate phase before it is stable in the bulk.

Continuous pCO2 time series from Ocean Networks Canada cabled observatories at the northeast Pacific shelf edge and in the sub-tidal Arctic

NASA Astrophysics Data System (ADS)

Juniper, S. Kim; Sastri, Akash; Mihaly, Steven; Duke, Patrick; Else, Brent; Thomas, Helmuth; Miller, Lisa

2017-04-01

Marine pCO2 sensor technology has progressed to the point where months-long time series from remotely-deployed pCO2 sensors can be used to document seasonal and higher frequency variability in pCO2 and its relationship to oceanographic processes. Ocean Networks Canada recently deployed pCO2 sensors on two cabled platforms: a bottom-moored (400 m depth), vertical profiler at the edge of the northeast Pacific continental shelf off Vancouver Island, Canada, and a subtidal seafloor platform in the Canadian High Arctic (69˚ N) at Cambridge Bay, Nunavut. Both platforms streamed continuous data to a shore-based archive from Pro-Oceanus pCO2 sensors and other oceanographic instruments. The vertical profiler time series revealed substantial intrusions of corrosive (high CO2/low O2), saltier, colder water masses during the summertime upwelling season and during winter-time reversals of along-slope currents. Step-wise profiles during the downcast provided the most reliable pCO2 data, permitting the sensor to equilibrate to the broad range of pCO2 concentrations encountered over the 400 metre depth interval. The Arctic pCO2 sensor was deployed in August 2015. Reversing seasonal trends in pCO2 and dissolved oxygen values can be related to the changing balance of photosynthesis and respiration under sea ice, as influenced by irradiance. Correlation of pCO2 and dissolved oxygen sensor data and the collection of calibration samples have permitted evaluation of sensor performance in relation to operational conditions encountered in vertical profiling and lengthy exposure to subzero seawater.

Subzero water permeability parameters and optimal freezing rates for sperm cells of the southern platyfish, Xiphophorus maculatus.

PubMed

Pinisetty, D; Huang, C; Dong, Q; Tiersch, T R; Devireddy, R V

2005-06-01

This study reports the subzero water transport characteristics (and empirically determined optimal rates for freezing) of sperm cells of live-bearing fishes of the genus Xiphophorus, specifically those of the southern platyfish Xiphophorus maculatus. These fishes are valuable models for biomedical research and are commercially raised as ornamental fish for use in aquariums. Water transport during freezing of X. maculatus sperm cell suspensions was obtained using a shape-independent differential scanning calorimeter technique in the presence of extracellular ice at a cooling rate of 20 degrees C/min in three different media: (1) Hanks' balanced salt solution (HBSS) without cryoprotective agents (CPAs); (2) HBSS with 14% (v/v) glycerol, and (3) HBSS with 10% (v/v) dimethyl sulfoxide (DMSO). The sperm cell was modeled as a cylinder with a length of 52.35 microm and a diameter of 0.66 microm with an osmotically inactive cell volume (Vb) of 0.6 V0, where V0 is the isotonic or initial cell volume. This translates to a surface area, SA to initial water volume, WV ratio of 15.15 microm(-1). By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the best fit membrane permeability parameters (reference membrane permeability to water at 0 degrees C, Lpg or Lpg [cpa] and the activation energy, E(Lp) or E(Lp) [cpa]) were found to range from: Lpg or Lpg [cpa] = 0.0053-0.0093 microm/minatm; E(Lp) or E(Lp) [cpa] = 9.79-29.00 kcal/mol. By incorporating these membrane permeability parameters in a recently developed generic optimal cooling rate equation (optimal cooling rate, [Formula: see text] where the units of B(opt) are degrees C/min, E(Lp) or E(Lp) [cpa] are kcal/mol, L(pg) or L(pg) [cpa] are microm/minatm and SA/WV are microm(-1)), we determined the optimal rates of freezing X. maculatus sperm cells to be 28 degrees C/min (in HBSS), 47 degrees C/min (in HBSS+14% glycerol) and 36 degrees C/min (in HBSS+10% DMSO). Preliminary empirical experiments suggest that the optimal rate of freezing X. maculatus sperm in the presence of 14% glycerol to be approximately 25 degrees C/min. Possible reasons for the observed discrepancy between the theoretically predicted and experimentally determined optimal rates of freezing X. maculatus sperm cells are discussed.

Evaluating the effect of soil dust particles from semi-arid areas on clouds and climate

NASA Astrophysics Data System (ADS)

Kristjansson, J. E.; Hummel, M.; Lewinschal, A.; Grini, A.

2016-12-01

Primary ice production in mixed-phase clouds predominantly takes place by heterogeneous freezing of mineral dust particles. Therefore, mineral dust has a large impact on cloud properties. Organic matter attached to mineral dust particles can expand their already good freezing ability further to warmer subzero temperatures. These dust particles are called "soil dust". Dusts emitted from deserts contribute most to the total dust concentration in the atmosphere and they can be transported over long distances. Soil dust is emitted from semi-arid regions, e.g. agricultural areas. Besides wind erosion, human activities like tillage or harvest might be a large source for soil dust release into the atmosphere. In this study, we analyze the influence of soil dust particles on clouds with the Norwegian Earth System Model (NorESM; Bentsen et al., 2013: GMD). The parameterization of immersion freezing on soil dust is based on findings from the AIDA cloud chamber (Steinke et al., in prep.). Contact angle and activation energy for soil dust are estimated in order to be used in the dust immersion freezing scheme of the model, which is based on classical nucleation theory. Our first results highlight the importance of soil dust for ice nucleation on a global scale. Its influence is expected to be highest in the northern hemisphere due to its higher area for soil dust emission. The immersion freezing rates due to additional soil dust can on average increase by a factor of 1.2 compared to a mineral dust-only simulation. Using a budget tool for NorESM, influences of soil dust ice nuclei on single tendencies of the cloud microphysics can be identified. For example, accretion to snow is sensitive to adding soil dust ice nuclei. This can result in changes e.g. in the ice water path and cloud radiative properties.

Persistent Supercooling of Reproductive Shoots Is Enabled by Structural Ice Barriers Being Active Despite an Intact Xylem Connection

PubMed Central

Pfaller, Kristian; Wagner, Johanna

2016-01-01

Extracellular ice nucleation usually occurs at mild subzero temperatures in most plants. For persistent supercooling of certain plant parts ice barriers are necessary to prevent the entry of ice from already frozen tissues. The reproductive shoot of Calluna vulgaris is able to supercool down to below -22°C throughout all developmental stages (shoot elongation, flowering, fruiting) despite an established xylem conductivity. After localization of the persistent ice barrier between the reproductive and vegetative shoot at the base of the pedicel by infrared differential thermal analysis, the currently unknown structural features of the ice barrier tissue were anatomically analyzed on cross and longitudinal sections. The ice barrier tissue was recognized as a 250 μm long constriction zone at the base of the pedicel that lacked pith tissue and intercellular spaces. Most cell walls in this region were thickened and contained hydrophobic substances (lignin, suberin, and cutin). A few cell walls had what appeared to be thicker cellulose inclusions. In the ice barrier tissue, the area of the xylem was as much as 5.7 times smaller than in vegetative shoots and consisted of tracheids only. The mean number of conducting units in the xylem per cross section was reduced to 3.5% of that in vegetative shoots. Diameter of conducting units and tracheid length were 70% and 60% (respectively) of that in vegetative shoots. From vegetative shoots water transport into the ice barrier must pass pit membranes that are likely impermeable to ice. Pit apertures were about 1.9 μm x 0.7 μm, which was significantly smaller than in the vegetative shoot. The peculiar anatomical features of the xylem at the base of the pedicel suggest that the diameter of pores in pit membranes could be the critical constriction for ice propagation into the persistently supercooled reproductive shoots of C. vulgaris. PMID:27632365

Light Weight Design Nickel-Alkaline Cells Using Fiber Electrodes

NASA Technical Reports Server (NTRS)

Pickett, David F.; Willis, Bob; Britton, Doris; Saelens, Johan

2005-01-01

Using fiber electrode technology, currently produced by Bekaert Corporation (Bekaert), Electro Energy, Inc., (EEI) Mobile Energy Products Group (formerly, Eagle-Picher Technologies, LLC., Power Systems Department) in Colorado Springs, CO has demonstrated that it is feasible to manufacture flight weight nickel-hydrogen cells having about twice the specific energy (80 vs. 40 watt-hr/kg) as state-of-the-art nickel-hydrogen cells that are flown on geosynchronous communications satellites. Although lithium-ion battery technology has made large in-roads to replace the nickel-alkaline technology (nickel-cadmium, nickel-metal hydride), the technology offered here competes with lithium-ion weight and offers alternatives not present in the lithium-ion chemistry such as ability to undergo continuous overcharge, reversal on discharge and sustain rate capability sufficient to start automotive and aircraft engines at subzero temperatures. In development to date seven 50 ampere-hour nickel-hydrogen have been constructed, acceptance tested and briefly tested in a low earth orbit (LEO) cycle regime. The effort was jointly funded by Electro Energy, Inc. and NASA Glenn Research Center, Cleveland, OH. Five of the seven cells have been shipped to NASA GRC for further cycle testing. Two of the cells experienced failure due to internal short circuits during initial cycle testing at EEL Destructive Physical Analysis (DPA) of one of the cells has shown the failure mode to be due to inadequate hydrogen catalyst electrodes that were not capacity balanced with the higher energy density nickel oxide electrodes. In the investigators opinion, rebuild of the cells using proper electrode balance would result in cells that could sustain over 30,000 cycles at moderate depths-of-discharge in a LEO regime or endure over 20 years of geosynchronous orbit (GEO) cycling while realizing a two-fold increase in specific energy for the battery or a 1.1 kg weight savings per 50 ampere-hour cell. Additional information is included in the original extended abstract.

Persistent Supercooling of Reproductive Shoots Is Enabled by Structural Ice Barriers Being Active Despite an Intact Xylem Connection.

PubMed

Kuprian, Edith; Tuong, Tan D; Pfaller, Kristian; Wagner, Johanna; Livingston, David P; Neuner, Gilbert

2016-01-01

Extracellular ice nucleation usually occurs at mild subzero temperatures in most plants. For persistent supercooling of certain plant parts ice barriers are necessary to prevent the entry of ice from already frozen tissues. The reproductive shoot of Calluna vulgaris is able to supercool down to below -22°C throughout all developmental stages (shoot elongation, flowering, fruiting) despite an established xylem conductivity. After localization of the persistent ice barrier between the reproductive and vegetative shoot at the base of the pedicel by infrared differential thermal analysis, the currently unknown structural features of the ice barrier tissue were anatomically analyzed on cross and longitudinal sections. The ice barrier tissue was recognized as a 250 μm long constriction zone at the base of the pedicel that lacked pith tissue and intercellular spaces. Most cell walls in this region were thickened and contained hydrophobic substances (lignin, suberin, and cutin). A few cell walls had what appeared to be thicker cellulose inclusions. In the ice barrier tissue, the area of the xylem was as much as 5.7 times smaller than in vegetative shoots and consisted of tracheids only. The mean number of conducting units in the xylem per cross section was reduced to 3.5% of that in vegetative shoots. Diameter of conducting units and tracheid length were 70% and 60% (respectively) of that in vegetative shoots. From vegetative shoots water transport into the ice barrier must pass pit membranes that are likely impermeable to ice. Pit apertures were about 1.9 μm x 0.7 μm, which was significantly smaller than in the vegetative shoot. The peculiar anatomical features of the xylem at the base of the pedicel suggest that the diameter of pores in pit membranes could be the critical constriction for ice propagation into the persistently supercooled reproductive shoots of C. vulgaris.

Oscillations and accelerations of ice crystal growth rates in microgravity in presence of antifreeze glycoprotein impurity in supercooled water.

PubMed

Furukawa, Yoshinori; Nagashima, Ken; Nakatsubo, Shun-Ichi; Yoshizaki, Izumi; Tamaru, Haruka; Shimaoka, Taro; Sone, Takehiko; Yokoyama, Etsuro; Zepeda, Salvador; Terasawa, Takanori; Asakawa, Harutoshi; Murata, Ken-Ichiro; Sazaki, Gen

2017-03-06

The free growth of ice crystals in supercooled bulk water containing an impurity of glycoprotein, a bio-macromolecule that functions as 'antifreeze' in living organisms in a subzero environment, was observed under microgravity conditions on the International Space Station. We observed the acceleration and oscillation of the normal growth rates as a result of the interfacial adsorption of these protein molecules, which is a newly discovered impurity effect for crystal growth. As the convection caused by gravity may mitigate or modify this effect, secure observations of this effect were first made possible by continuous measurements of normal growth rates under long-term microgravity condition realized only in the spacecraft. Our findings will lead to a better understanding of a novel kinetic process for growth oscillation in relation to growth promotion due to the adsorption of protein molecules and will shed light on the role that crystal growth kinetics has in the onset of the mysterious antifreeze effect in living organisms, namely, how this protein may prevent fish freezing.

Oscillations and accelerations of ice crystal growth rates in microgravity in presence of antifreeze glycoprotein impurity in supercooled water

PubMed Central

Furukawa, Yoshinori; Nagashima, Ken; Nakatsubo, Shun-ichi; Yoshizaki, Izumi; Tamaru, Haruka; Shimaoka, Taro; Sone, Takehiko; Yokoyama, Etsuro; Zepeda, Salvador; Terasawa, Takanori; Asakawa, Harutoshi; Murata, Ken-ichiro; Sazaki, Gen

2017-01-01

The free growth of ice crystals in supercooled bulk water containing an impurity of glycoprotein, a bio-macromolecule that functions as ‘antifreeze’ in living organisms in a subzero environment, was observed under microgravity conditions on the International Space Station. We observed the acceleration and oscillation of the normal growth rates as a result of the interfacial adsorption of these protein molecules, which is a newly discovered impurity effect for crystal growth. As the convection caused by gravity may mitigate or modify this effect, secure observations of this effect were first made possible by continuous measurements of normal growth rates under long-term microgravity condition realized only in the spacecraft. Our findings will lead to a better understanding of a novel kinetic process for growth oscillation in relation to growth promotion due to the adsorption of protein molecules and will shed light on the role that crystal growth kinetics has in the onset of the mysterious antifreeze effect in living organisms, namely, how this protein may prevent fish freezing. PMID:28262787

Design and Development of a Sub-Zero Fluid System for Demonstration of Orion's Phase Change Material Heat Exchangers on ISS

NASA Technical Reports Server (NTRS)

Sheth, Rubik B.; Ahlstrom, Thomas D.; Le, Hung V.

2016-01-01

NASA's Orion Multipurpose Crew Vehicle's Exploration Mission 2 is expected to loiter in Lunar orbit for a relatively long period of time. In low Lunar orbit (LLO) the thermal environment is cyclic - extremely cold in the eclipse and relatively hot near the subsolar point. Phase change material heat exchangers (PCM HXs) are the best option for long term missions in these environments. A PCM HX allows a vehicle to store excess waste energy by thawing a phase change material such as n-pentadecane wax. During portions of the orbit that are extremely cold, the excess energy is rejected, resolidifying the wax. Due to the inherent risk of compromising the heat exchanger during multiple freeze and thaw cycles, a unique payload was designed for the International Space Station to test and demonstration the functions of a PCM HX. The payload incorporates the use of a pumped fluid system and a thermoelectric heat exchanger to promote the freezing and thawing of the PCM HX. This paper shall review the design and development undertaken to build such a system.

The Effects of Cryogenic Treatment on Cutting Tools

NASA Astrophysics Data System (ADS)

Kumar, Satish; Khedkar, Nitin K.; Jagtap, Bhushan; Singh, T. P.

2017-08-01

Enhancing the cutting tool life is important and economic factor to reduce the tooling as well as manufacturing cost. The tool life is improved considerably by 92 % after cryogenic treatment. The cryogenic treatment is a one-time permanent, sub-zero heat treatment that entirely changes cross-section of cutting tool. The cryogenic treatment is carried out with deep freezing of cutting tool materials to enhance physical and mechanical properties. The cryogenic treatment improves mechanical such as hardness, toughness and tribological properties such as wear resistance, coefficient of friction, surface finish, dimensional stability and stress relief. The deep cryogenic treatment is the most beneficial treatment applied on cutting tools. The cryogenic treatment is the most advanced heat treatment and popular to improve performance of the cutting tool. The optimization of cryogenic treatment variables is necessary to improve tool life. This study reviews the effects of cryogenic treatment on microstructure, tribological properties of tool steels and machining applications of cutting tool by investigating the surface and performing the surface characterization test like SEM. The economy of cutting tool can be achieved by deep cryogenic treatment.

Terrestrial Permafrost Models of Martian Habitats and Inhabitants

NASA Astrophysics Data System (ADS)

Gilichinsky, D.

2011-12-01

The terrestrial permafrost is the only rich depository of viable ancient microorganisms on Earth, and can be used as a bridge to possible Martian life forms and shallow subsurface habitats where the probability of finding life is highest. Since there is a place for water, the requisite condition for life, the analogous models are more or less realistic. If life ever existed on Mars, traces might have been preserved and could be found at depth within permafrost. The age of the terrestrial isolates corresponds to the longevity of the frozen state of the embedding strata, with the oldest known dating back to the late Pliocene in Arctic and late Miocene in Antarctica. Permafrost on Earth and Mars vary in age, from a few million years on Earth to a few billion years on Mars. Such a difference in time scale would have a significant impact on the possibility of preserving life on Mars, which is why the longevity of life forms preserved within terrestrial permafrost can only be an approximate model for Mars. 1. A number of studies indicate that the Antarctic cryosphere began to develop on the Eocene-Oligocene boundary, after the isolation of the continent. Permafrost degradation is only possible if mean annual ground temperature, -28°C now, rise above freezing, i.e., a significant warming to above 25°C is required. There is no evidence of such sharp temperature increase, which indicates that the climate and geological history was favorable to persistence of pre-Pliocene permafrost. These oldest relics (~30Myr) are possibly to be found at high hypsometric levels of ice-free areas (Dry Valleys and nearby mountains). It is desirable to test the layers for the presence of viable cells. The limiting age, if one exists, within this ancient permafrost, where the viable organisms were no longer present, could be established as the limit for life preservation below 0oC. Positive results will extend the known temporal limits of life in permafrost. 2. Even in this case, the age of Martian permafrost is still 100 times older. Only one terrestrial environment is close to Mars in age - volcanoes in permafrost areas. The age of volcanic deposits frozen after eruption is much younger than the age of surrounding permafrost. Culture- and culture-independent methods show the presence of viable thermophiles and their genes within pyroclastic frozen material on Deception Island, Antarctica and Kamchatka peninsula. These bacteria and archeae have not been found in permafrost outside the volcanic areas. The only way for thermophiles to get into frozen soil is through deposition during eruption, i.e. the catastrophic geological events transport microbes from the depths to the surface and they survive at subzero temperatures. The past activity of Martian volcanoes periodically burned through the frozen strata and products of eruptions rose from the depths to the surface and froze. Images taken by the Stereo Camera on board the Mars Express discovered volcanoes 2-15Myr old that date back to ages close to permafrost on Earth. Terrestrial communities might serve as a model of inhabitants for these young volcanoes. 3. The only opportunity for free water on Mars is the overcooled water brines, and halo/psychrophilc community of Arctic cryopegs, sandwiched within permafrost, represents a plausible prototype for Martian microbial life.

Use Of Amino Acid Racemization To Investigate The Metabolic Activity Of ?Dormant? Microorganisms In Siberian Permafrost

NASA Astrophysics Data System (ADS)

Tsapin, A.; McDonald, G.

2002-12-01

Permafrost occupies a significant part of North America and Eurasia, and accounts for around 20% of Earth?s land surface. Permafrost represents a temperature-stable environment that allows the prolonged survival of microbial lineages at subzero temperatures. Microorganisms from ancient permafrost have been revived and isolated in pure cultures. Permafrost is a unique environment serving as a "natural gene bank", with many species frozen in time (i.e. preserved in an unchanging evolutionary state). Permafrost presents a golden niche for future biotechnology, and is also a unique environment for studying longevity and survivability microorganisms (pro- and eukaryotes). Permafrost, alone among cold environments, offers a sedimentary column in which, in one borehole made in the thick permafrost, we can observe in the preserved genetic material the history of biological evolution during the last several hundred thousand or maybe even a few million years. A thorough study of the phylogenetic relationships of organisms at each depth, as well as comparisons between different depths of permafrost, using molecular evolution techniques, will give us a unique window into the process of evolution of microbial communities over geologic time. The longevity of (micro)organisms in cold environments is of great interest to astrobiology since cryospheres are common phenomena in the solar system, particularly on satellites, comets and asteroids, and on some of the planets. Recent data from the Mars Global Surveyor mission suggest the possibility of permafrost or perhaps even liquid water under the Martian surface. The probability of finding life on Mars, if it exists, is probably higher in such environments. In addition, the evaluation of the possibility of transfer of living organisms between planets via impact ejecta needs the information on the maximum time over which microorganisms in cold environments can remain dormant and subsequently revive and reproduce. Our strategy for the search for extraterrestrial life or its remnants is based on studying the most probable environments in which life (extant or extinct) may be found, and determining the maximum period of time over which such life could be preserved. The terrestrial permafrost, inhabited by cold adapted microbes, can be considered as an extraterrestrial analog environment. The cells and their metabolic end-products in Earth's permafrost can be used in the search for possible ecosystems and potential inhabitants on extraterrestrial cryogenic bodies. The study of microorganisms (or their remnants) that were buried for a few million years in permafrost provides us with a unique opportunity to determine the long-term viability of (micro)organisms. We have analyzed the degree of racemization of aspartic acid in permafrost samples from Northern Siberia (Brinton et al. 2002, Astrobiology 2, 77), an area from which microorganisms of apparent ages up to a few million years have previously been isolated and cultured. We find that the extent of aspartic acid racemization in permafrost cores increases very slowly up to an age of approximately 25,000 years (around 5 m depth). The apparent temperature of racemization over the age range 0-25,000 years, determined using measured aspartic acid racemization rate constants, is ?19 C. This apparent racemization temperature is significantly lower than the measured environmental temperature (?11 to ?13 C), and suggests active recycling of D-aspartic acid in Siberian permafrost up to an age of around 25,000 years. This indicates that permafrost organisms are capable of repairing some molecular damage incurred while they are in a ?dormant? state over geologic time.

Cold weather effects on Dresden Unit 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anagnostopoulos, H.

1995-03-01

Dresden Unit 1 is in the final stages of a decommissioning effort directed at preparing the unit to enter a SAFSTOR status. Following an extended sub-zero cold wave, about 55,000 gallons of water were discovered in the lowest elevation of the spherical reactor enclosure. Cold weather had caused the freezing and breaking of several service water lines that had not been completely isolated. Two days later, at a regularly scheduled decommissioning meeting, the event was communicated to the decommissioning team, who quickly recognized the potential for freezing of a 42 inches diameter Fuel Transfer Tube that connects the sphere tomore » the Spent Fuel Pool. The team directed that the pool gates between the adjacent Spent Fuel Pool and the Fuel Transfer Pool be installed, and a portable source of heat was installed on the Fuel Transfer Tube. It was later determined that, with the fuel pool gates removed, and with a worst case freeze break at the 502 elevation on the Fuel Transfer Tube (in the Sphere), the fuel in the Spent Fuel Pool could be uncovered to a level 3 below the top of active fuel.« less

Determination of 14C age of inorganic and organic carbon in ancient Siberian permafrost

NASA Astrophysics Data System (ADS)

Onstott, T. C.; Liang, R.; Lau, M.; Vishnivetskaya, T. A.; Lloyd, K. G.; Pfiffner, S. M.; Hodgins, G.; Rivkina, E.

2017-12-01

Permafrost represents a large reservoir of ancient carbon that could have an important impact on the global carbon budget during climate warming. Due to the low turnover rate of carbon by microorganisms at subzero temperatures, the persistence of ancient carbon in younger permafrost deposits could also pose challenges for radiocarbon dating of permafrost sediment. We utilized Accelerator Mass Spectrometry to determine the 14C age of inorganic carbon, labile and recalcitrant organic carbon in Siberian permafrost sediment sampled at various depths from 2.9 to 5.6m. The fraction of inorganic carbon (CO2) was collected after acidification using phosphoric acid. The labile (younger) and recalcitrant (old) organic carbon in the subsequent residues were collected after combustion at 400 ºC and 800 ºC, respectively. The percentages of inorganic carbon increased from the youngest (2.9m) to the oldest (5.6m), whereas the fractions for organic carbon varied significantly at different depths. The 14C age determined in the inorganic fraction in the top sample (2.9 m) was 21,760 yr BP and gradually increased to 33,900 yr BP in the relative deeper sediment (3.5 and 5.6 m). Surprisingly, the fraction of "younger" carbon liberated at 400 oC was older than the more recalcitrant and presumably older organic carbon liberated at 800 oC in all cases. Moreover, the 14C age of the younger and older organic carbon fractions did not increase with depth as observed in the carbonate fraction. In particular, the 14C age of the organic carbon in the top sample (38,590-41,700 yr BP) was much older than the deeper samples at depth of 3.5m (18,228-20,158 yr BP) and 5.6m (29,040-38,020 yr BP). It should be noticed that the metabolism of ancient carbon in frozen permafrost may vary at different depths due to the different proportion of necromass and metabolically active microbes. Therefore, additional knowledge about the carbon dynamics of permafrost and more investigation would be required to resolve these unexpected 14C observations relative to stratigraphic ages.

Diversity and survivability of microbial community in ancient permafrost sediment of northeast Siberia

NASA Astrophysics Data System (ADS)

Liang, R.; Lau, M.; Vishnivetskaya, T. A.; Lloyd, K. G.; Pfiffner, S. M.; Rivkina, E.; Onstott, T. C.

2017-12-01

The prevalence of microorganisms in frozen permafrost has been well documented in ancient sediment up to several million years old. However, the long term survivability and metabolic activity of microbes over geological timespans remain underexplored. Siberian permafrost sediment was collected at various depths (1.4m, 11.8 m and 24.8m) to represent a wide range of geological time from thousands to millions of years. Extracellular (eDNA) and intracellular DNA (iDNA) was simultaneously recovered for sequencing to characterize the potentially extinct and extant microbial community. Additionally, aspartic acid racemization assay (D/L Asp) was used to infer the metabolic activity of microbes in ancient permafrost. As compared with the young sample (1.4m), DNA yield and content of aspartic acid dramatically decreased in old samples (11.8m and 24.8m). However, D/L Asp and eDNA/iDNA significantly increased with the geological age. Such findings suggested that ancient microbiomes might be subjected to racemization or even DNA/proteins degradation at subzero temperature over the wide geological time scale. Preliminary characterization of microbial community indicated that the majority of sequences in old samples were identified as bacteria and only a small fraction was identified as archaea from the iDNA pool. While the eDNA and iDNA fractions shared similar dominant taxa at phylum level, the relative abundance of Proteobacteria in eDNA library was much higher than iDNA. By contrast, the phylum affiliated with Firmicutes was more numerically abundant in the iDNA fraction. More dramatic differences were observed between eDNA and iDNA library at lower taxonomic levels. Particularly, the microbial lineages affiliated with the genera Methanoregula, Desulfosporosinus and Syntrophomonas were only detected in the iDNA library. Such taxonomic difference between the relic eDNA and iDNA suggested that numerous species become locally "extinct" whereas many other taxa might survive in ancient sediment. Ultimately, when coupling our current findings to the D/L Asp in cellular proteins and metaproteomics, a better understanding will be achieved about the microbial activity of the extant microbial community and their roles in biogeochemical cycling in ancient permafrost.

Does winter desiccation account for seasonal increases in supercooling capacity of Norway spruce bud primordia?

PubMed Central

Koch, Sabrina; Munkler, Caspar; Resnyak, Anna; Buchner, Othmar; Oberhammer, Marian; Neuner, Gilbert

2018-01-01

Abstract Bud primordia of Picea abies (L.) H. Karst. remain ice free at subzero temperatures by supercooling. Once ice forms inside the primordium, it is immediately injured. Supercooling capacity increases seasonally from ~−5 °C to as much as −50 °C by currently unknown mechanisms. Among other prerequisites, dehydration of tissues over the winter months has been considered to play a key role in freezing tolerance. In this regard, the water content of bud primordia may be crucial, especially in reference to supercooling. In order to assess the role of dehydration in supercooling capacity, seasonal changes in supercooling capacity and the water potential of bud primordia of Picea abies (L.) H. Karst were measured at two sites that differed by 1298 m in elevation, after artificial frost hardening and dehardening treatments and after controlled bench drying. The extent of supercooling of bud primordia varied from −7 °C in summer to −24.6 °C in winter, a difference of 17.6 –19.3 K. Total actual water potential (Ψtact) of bud primordia was −2 MPa in summer and decreased to a mean of −3.8 MPa in midwinter. The decline involved dehydration, and to a lesser extent, osmoregulation. At decreased Ψtact values (<3.0 MPa), supercooling capacity significantly increased <−19.5 °C, however, the correlation between actual water potential and supercooling capacity was poor. Frost-hardening treatments increased the supercooling capacity of bud primordia (−0.6 K day−1) and lowered Ψtact (−0.2 MPa day−1). Frost-dehardening treatments reduced supercooling capacity (+1.1 K day−1), and at the same time, increased Ψtact (+0.3 MPa day−1). In contrast, artificial drying of bud primordia in the range observed seasonally (−2.0 MPa) had no effect on supercooling capacity. These results suggest that there is no causal relationship between desiccation and the supercooling capacity of bud primordia in P. abies, but rather it involves other compounds within the cells of the bud primordium that reduce the water potential. PMID:29182788

Advances in heterogeneous ice nucleation research: Theoretical modeling and measurements

NASA Astrophysics Data System (ADS)

Beydoun, Hassan

In the atmosphere, cloud droplets can remain in a supercooled liquid phase at temperatures as low as -40 °C. Above this temperature, cloud droplets freeze via heterogeneous ice nucleation whereby a rare and poorly understood subset of atmospheric particles catalyze the ice phase transition. As the phase state of clouds is critical in determining their radiative properties and lifetime, deficiencies in our understanding of heterogeneous ice nucleation poses a large uncertainty on our efforts to predict human induced global climate change. Experimental challenges in properly simulating particle-induced freezing processes under atmospherically relevant conditions have largely contributed to the absence of a well-established model and parameterizations that accurately predict heterogeneous ice nucleation. Conversely, the sparsity of reliable measurement techniques available struggle to be interpreted by a single consistent theoretical or empirical framework, which results in layers of uncertainty when attempting to extrapolate useful information regarding ice nucleation for use in atmospheric cloud models. In this dissertation a new framework for describing heterogeneous ice nucleation is developed. Starting from classical nucleation theory, the surface of an ice nucleating particle is treated as a continuum of heterogeneous ice nucleating activity and a particle specific distribution of this activity g is derived. It is hypothesized that an individual particle species exhibits a critical surface area. Above this critical area the ice nucleating activity of a particle species can be described by one g distribution, g, while below it g expresses itself expresses externally resulting in particle to particle variability in ice nucleating activity. The framework is supported by cold plate droplet freezing measurements for dust and biological particles in which the total surface area of particle material available is varied. Freezing spectra above a certain surface area are shown to be successfully fitted with g while a process of random sampling from g can predict the freezing behavior below the identified critical surface area threshold. The framework is then extended to account for droplets composed of multiple particle species and successfully applied to predict the freezing spectra of a mixed proxy for an atmospheric dust-biological particle system. The contact freezing mode of ice nucleation, whereby a particle induces freezing upon collision with a droplet, is thought to be more efficient than particle initiated immersion freezing from within the droplet bulk. However, it has been a decades' long challenge to accurately measure this ice nucleation mode, since it necessitates reliably measuring the rate at which particles hit a droplet surface combined with direct determination of freezing onset. In an effort to remedy this longstanding deficiency a temperature controlled chilled aerosol optical tweezers capable of stably isolating water droplets in air at subzero temperatures has been designed and implemented. The new temperature controlled system retains the powerful capabilities of traditional aerosol optical tweezers: retrieval of a cavity enhanced Raman spectrum which could be used to accurately determine the size and refractive index of a trapped droplet. With these capabilities, it is estimated that the design can achieve ice supersaturation conditions at the droplet surface. It was also found that a KCl aqueous droplet simultaneously cooling and evaporating exhibited a significantly higher measured refractive index at its surface than when it was held at a steady state temperature. This implies the potential of a "salting out" process. Sensitivity of the cavity enhanced Raman spectrum as well as the visual image of a trapped droplet to dust particle collisions is shown, an important step in measuring collision frequencies of dust particles with a trapped droplet. These results may pave the way for future experiments of the exceptionally poorly understood contact freezing mode of ice nucleation.

Formation of lobate debris aprons on Mars: Assessment of regional ice sheet collapse and debris-cover armoring

NASA Astrophysics Data System (ADS)

Fastook, James L.; Head, James W.; Marchant, David R.

2014-01-01

Lobate debris aprons (LDA) are lobate-shaped aprons surrounding scarps and isolated massifs that are concentrated in the vicinity of the northern Dichotomy Boundary on Mars. LDAs have been interpreted as (1) ice-cemented talus aprons undergoing viscous flow, (2) local debris-covered alpine-like glaciers, or (3) remnants of the collapse of a regional retreating ice sheet. We investigate the plausibility that LDAs are remnants of a more extensive regional ice sheet by modeling this process. We find that as a regional ice sheet collapses, the surface drops below cliff and massif bedrock margins, exposing bedrock and regolith, and initiating debris deposition on the surface of a cold-based glacier. Reduced sublimation due to debris-cover armoring of the proto-LDA surface produces a surface slope and consequent ice flow that carries the armoring debris away from the rock outcrops. As collapse and ice retreat continue the debris train eventually reaches the substrate surface at the front of the glacier, leaving the entire LDA armored by debris cover. Using a simplified ice flow model we are able to characterize the temperature and sublimation rate that would be necessary to produce LDAs with a wide range of specified lateral extents and thicknesses. We then apply this method to a database of documented LDA parameters (height, lateral extent) from the Dichotomy Boundary region, and assess the implications for predicted climate conditions during their formation and the range of formation times implied by the model. We find that for the population examined here, typical temperatures are in the range of -85 to -40 °C and typical sublimation rates lie in the range of 6-14 mm/a. Lobate debris apron formation times (from the point of bedrock exposure to complete debris cover) cluster near 400-500 ka. These results show that LDA length and thickness characteristics are consistent with climate conditions and a formation scenario typical of the collapse of a regional retreating ice sheet and exposure of bedrock cliffs. This scenario helps resolve many of the unusual characteristics of lobate debris aprons (LDA) and lineated valley fill (LVF). For example, the distribution of LVF is very consistent with extensive flow of glacial ice from plateau icefields, and the acquisition of a debris cover in the waning stages of retreat of the regional cover as the bedrock scarps are exposed. The typical concentric development of LDA around massifs is much more consistent with ice sheet retreat than insolation-related local accumulation and flow. We thus conclude that the retreating ice-sheet model is robust and should be investigated and tested in more detail. In addition, these results clearly show that the lobate debris aprons in the vicinity of the Dichotomy Boundary could not have attained temperatures near or above the ice melting point and retained their current shape, a finding that supports subzero temperatures for the last several hundred million years, the age of the LDA surfaces. A further implication is that the LDA ice has been preserved for at least several hundred million years, and could potentially contain the record of the climate of Mars, preserved since that time below a sublimation lag deposit.

500 C Electronic Packaging and Dielectric Materials for High Temperature Applications

NASA Technical Reports Server (NTRS)

Chen, Liang-yu; Neudeck, Philip G.; Spry, David J.; Beheim, Glenn M.; Hunter, Gary W.

2016-01-01

High-temperature environment operable sensors and electronics are required for exploring the inner solar planets and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500C. A compatible packaging system is essential for long-term testing and application of high temperature electronics and sensors. High temperature passive components are also necessary for high temperature electronic systems. This talk will discuss ceramic packaging systems developed for high temperature electronics, and related testing results of SiC circuits at 500C and silicon-on-insulator (SOI) integrated circuits at temperatures beyond commercial limit facilitated by these high temperature packaging technologies. Dielectric materials for high temperature multilayers capacitors will also be discussed. High-temperature environment operable sensors and electronics are required for probing the inner solar planets and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500C. A compatible packaging system is essential for long-term testing and eventual applications of high temperature electronics and sensors. High temperature passive components are also necessary for high temperature electronic systems. This talk will discuss ceramic packaging systems developed for high electronics and related testing results of SiC circuits at 500C and silicon-on-insulator (SOI) integrated circuits at temperatures beyond commercial limit facilitated by high temperature packaging technologies. Dielectric materials for high temperature multilayers capacitors will also be discussed.

Research and Development in the Anthropogenic Cryosphere

NASA Astrophysics Data System (ADS)

de Jong, C.; Luthe, T.; Hohenwallne, D.

2009-04-01

Much of todays cryosphere research is oriented towards the polar regions and is strongly supported by large associations and funding. On the other hand, funding and institutional support is still limited for mountains. In Europe, mountain research is mainly funded through Alpine Space Interregs, FP7, ESF and COST. However, there is growing global change pressure on mountain regions, particularly in the more fragile, higher altitudes such as between 1000 - 3200 m in the Alps. Although these zones are comparable to the Arctic in terms of climatic and physiographic conditions, they are not in terms of human pressures and atmospheric pollution released from surrounding agglomerations. A re-orientation of research into more applied projects that tackle present day problems is necessary. Not only is climate change rapidly changing the face of mountains, socio-economic multipliers are also acting fast. New problems such as conflicts over natural resources are evolving at a rapid rate, requiring research funding and projects to respond at according rates if timely and efficient solutions are to be proposed. Other problems include contamination of high altitude lakes and ecosystems through atmospheric precipitation of persistent organic pollutants and concentration of radio-active substances. The rapid melt of glacier ice is also releasing pollutants that have been captured for many decades. Many of the present day problems develop due to a miscomprehension of the cryosphere. Short-term economical reasoning outweighs the long-term ecological impacts that could be very counter-productive at the long term. Both the glaciological, snow, permafrost, geomorphological, ecological, hydrological and atmospheric conditions are increasingly heavily modified by human impacts. The effects include the alteration of the ice cover (by artificial covering of glaciers), production of artificial snow cover, snow and ground compaction, erosion, landsliding, change in vegetation cover and fauna, modification of local hydrological cycle and modification of local climate and atmospheric pollution. Research in mountains should balance the needs of scientists and stakeholders alike, but this requires re-orientation of mountain research into multi-disciplinary projects next to basic science. Unlike the polar regions (with exceptions like Longyearbyen, Spitzbergen), seasonal population pressure in mountains is intense, causing local problems such as water scarcity. Research in these areas therefore requires close collaboration with stakeholders. Large-scale events such as Winter Olympics that have benefited from the classical mountain cryosphere in the past are now increasingly becoming internationally competitive and independent of the natural cryospheric conditions. New ski areas are developed world-wide in zones that do not offer natural climatological conditions for maintaining ski runs. Sub-zero temperatures are used as a basis for snow-making even in those regions that do not benefit from sufficient natural snow-fall. Large-scale landscape modification results in motorway like ski runs, large snow water reservoirs and extensive housing projects on vulnerable slopes. Due to steep and remote topography, transport is often dominated by cars and increases CO2 emissions intensively at local hot spots. In future, mountain slopes that have been heavily modified for winter tourism, may rapidly become neglected zones due to rapid snowline retreat. As the summer season extends, the modifications to the cryosphere will become more and more evident. Even with positive temperatures and snow-free ground, the vegetation season will not be extensive enough to enable rapid recovery, especially at altitudes above 2000 m a.s.l and north-facing aspects. Several decades of anthropogenic modification may require several centuries of recovery to provide new economical benefits.

FEM Modeling of the Relationship between the High-Temperature Hardness and High-Temperature, Quasi-Static Compression Experiment.

PubMed

Zhang, Tao; Jiang, Feng; Yan, Lan; Xu, Xipeng

2017-12-26

The high-temperature hardness test has a wide range of applications, but lacks test standards. The purpose of this study is to develop a finite element method (FEM) model of the relationship between the high-temperature hardness and high-temperature, quasi-static compression experiment, which is a mature test technology with test standards. A high-temperature, quasi-static compression test and a high-temperature hardness test were carried out. The relationship between the high-temperature, quasi-static compression test results and the high-temperature hardness test results was built by the development of a high-temperature indentation finite element (FE) simulation. The simulated and experimental results of high-temperature hardness have been compared, verifying the accuracy of the high-temperature indentation FE simulation.The simulated results show that the high temperature hardness basically does not change with the change of load when the pile-up of material during indentation is ignored. The simulated and experimental results show that the decrease in hardness and thermal softening are consistent. The strain and stress of indentation were analyzed from the simulated contour. It was found that the strain increases with the increase of the test temperature, and the stress decreases with the increase of the test temperature.

FEM Modeling of the Relationship between the High-Temperature Hardness and High-Temperature, Quasi-Static Compression Experiment

PubMed Central

Zhang, Tao; Jiang, Feng; Yan, Lan; Xu, Xipeng

2017-01-01

The high-temperature hardness test has a wide range of applications, but lacks test standards. The purpose of this study is to develop a finite element method (FEM) model of the relationship between the high-temperature hardness and high-temperature, quasi-static compression experiment, which is a mature test technology with test standards. A high-temperature, quasi-static compression test and a high-temperature hardness test were carried out. The relationship between the high-temperature, quasi-static compression test results and the high-temperature hardness test results was built by the development of a high-temperature indentation finite element (FE) simulation. The simulated and experimental results of high-temperature hardness have been compared, verifying the accuracy of the high-temperature indentation FE simulation.The simulated results show that the high temperature hardness basically does not change with the change of load when the pile-up of material during indentation is ignored. The simulated and experimental results show that the decrease in hardness and thermal softening are consistent. The strain and stress of indentation were analyzed from the simulated contour. It was found that the strain increases with the increase of the test temperature, and the stress decreases with the increase of the test temperature. PMID:29278398

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Bo; Nelson, Kevin; Lipinski, Ronald J.

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-temperature high-strain-rate performance are needed for understanding high-speed impacts in severe elevated-temperature environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain-rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. Current high-temperature Kolsky compression bar techniques are not capable of obtaining satisfactory high-temperature high-strain-rate stress-strain response of thin iridium specimens investigated in this study. We analyzedmore » the difficulties encountered in high-temperature Kolsky compression bar testing of thin iridium alloy specimens. Appropriate modifications were made to the current high-temperature Kolsky compression bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high strain rates (300 – 10000 s -1) and temperatures (750°C and 1030°C). Uncertainties in such high-temperature high-strain-rate experiments on thin iridium specimens were also analyzed. The compressive stress-strain response of the iridium alloy showed significant sensitivity to strain rate and temperature.« less

Reliability Evaluation of Low Power Schottky Clamped Microcircuits.

DTIC Science & Technology

1980-02-01

Temperature 52 15. 54LS191: ICC Versus Temperature 53 16. 54LS181: ICC Versus Temperature 54 17. High Temperature ...Response, Vendor A, 54LS181 56 18. High Temperature Response, Vendor B, 54LS181 57 19. High Temperature Response, Vendor A, 54LS191 58 20. High ... Temperature Response, Vendor B, 54LS191 59 21. High Temperature Response, Vendor A, 54LS251 60 3 LIST OF FIGURES (continued) Figure No. Title Page 22. High

Divergence of brain and retinal anatomy and histology in pelagic antarctic notothenioid fishes of the sister taxa Dissostichus and Pleuragramma.

PubMed

Eastman, Joseph T; Lannoo, Michael J

2011-04-01

The neutrally buoyant Antarctic fishes of the sister taxa Dissostichus (D. eleginoides and D. mawsoni) and Pleuragramma antarcticum diverged early in the notothenioid radiation and filled different niches in the pelagic realm of the developing Southern Ocean. To assess the influence of phylogenetic and ecological factors in shaping neural morphology in these taxa, we studied the anatomy and histology of the brains and retinae, and determined the proportional weights of brain regions. With the brain of the non-Antarctic sister taxon Eleginops maclovinus as plesiomorphic, statistically significant departures in the brains of the two Antarctic taxa include reduction of the corpus cerebelli and expansion of the mesencephalon and medulla. Compared to Eleginops, both species also have a relatively smaller telencephalon, although this is significant only in Dissostichus. There are a number of apomorphic features in the brain of Pleuragramma including reduced olfactory nerves and bulbs, an extremely small corpus cerebelli and an expanded mesencephalon. Although there is not a significant difference in the relative weights of the medulla in the two taxa, the prominence of the eminentia granularis and bulging cap-like appearance of the crista cerebellaris are distinctive in Pleuragramma. Brain histology of Dissostichus and Pleuragramma reflects typical perciform patterns and the two species of Dissostichus are histologically identical. Lateral compression in Pleuragramma and notable lobation in Dissostichus also contribute to differences between the taxa. Compression in Pleuragramma is attributable to convergence on an anchovy/herring body shape and to the relatively large brain in this small fish. The less prominent pattern of lobation of the telencephalon, inferior lobes and corpus cerebelli in Pleuragramma probably reflects underlying histology, specifically a reduction in cellularity of the neuropil in the nuclei and lobes. The retinal histology of Dissostichus and Pleuragramma encompasses the extremes seen in Antarctic notothenioids. Dissostichus has a thin scotopic retina with few cones and a high degree of summation. The retina of Pleuragramma is thick and cellular with many small single cones and rods and resembles that of Eleginops. Pedomorphy has not influenced brain morphology in these species but Pleuragramma has superficial neuromasts that are pedomorphic. Although Dissostichus and Pleuragramma are sympatric in the water column, their brains and retinae are highly divergent and reflect the influences of both phylogeny and ecological partitioning of the pelagic realm. Compared to Eleginops, the relatively smaller corpus cerebelli but relatively larger medulla probably indicates, respectively, reduced activity levels of notothenioids in subzero temperatures and expansion of the mechanosensory lateral line system as a supplement to vision under conditions of reduced light. Compared to Dissostichus, Pleuragramma has reduced olfactory bulbs and corpus cerebelli and an expanded mesencephalon. The reduction of the corpus to a small round knob is consistent with physiological parameters and video observations suggesting that, although pelagic, it is relatively inactive. Because mesencephalic weights also include the valvula cerebelli, the relatively large value for Pleuragramma may be attributable to its role in integration and sensorimotor coordination of information from the highly cellular duplex retina and to integration of signals from thewell-developed octavolateralis system. The brain of Dissostichus displays considerable persistent morphology in its overall resemblance to that of Eleginops, especially the large olfactory bulbs and the relatively large caudally projecting corpus, and Dissostichus exhibits olfactory tracking ability and migratory behavior in common with Eleginops. Copyright © 2011 Wiley-Liss, Inc.

Characterization and quantification of bioaerosols in Saharan dust transported across the Atlantic

NASA Astrophysics Data System (ADS)

Yordanova, Petya; Maier, Stefanie; Rodriguez-Caballero, Emilio; Ditas, Florian; Klimach, Thomas; Prass, Maria; Hrabe de Angelis, Isabella; Blades, Edmund; Holanda, Bruna; Pöhlker, Mira; Maurus, Isabel; Kopper, Gila; Farrell, David; Stevens, Bjorn; Prospero, Joseph M.; Ulrich, Pöschl; Andreae, Meinrat O.; Fröhlich-Nowoisky, Janine; Pöhlker, Christopher; Weber, Bettina

2017-04-01

Primary biological aerosols (bioaerosols), forming a subset of atmospheric particles, are directly released from the biosphere into the atmosphere. They comprise living and dead organisms (e.g., algae, bacteria, archaea), reproduction units (e.g., pollen, seeds, spores) as well as organism fragments and excretions. They play a key role in the dispersal of otherwise mostly sessile organisms (e.g. plants), but also in the spread of pathogens and diseases. Recently, also soil dust has been described to frequently occur in a close connection with biological particles (Conen et al., 2011). Bioaerosols can serve as nuclei for cloud droplets and ice crystals and may influence the radiative properties of the atmosphere, thus influencing the hydrological cycle and climate (Fröhlich-Nowoisky et al., 2016). It has been well described that dust masses are transported across the Atlantic comprising a large variety of bacteria and fungi, but the origin of the biological material remained largely unknown (Prospero et al., 2005). In the present study we aim to accomplish three major tasks, i.e., 1) Thorough identification and quantification of bioaerosol particles, 2) Characterization of ice nucleating (IN) properties of bioaerosols, and 3) Evaluation of similarities between bioaerosols and biological material in source regions of dust. For our field work we utilized filter techniques to collect aerosol samples of transatlantically transported dust at the easternmost site (Ragged Point) on the Caribbean island Barbados. Sampling took place from July to August 2016, when dust transport volumes were expected to reach peak amounts. Total suspended particles were collected ˜30 m above sea level using a high volume sampler (˜ 500 L min-1) and a micro-orifice uniform deposit impactor (MOUDI™) to obtain size-resolved samples. Directly after sampling at different time intervals (i.e. 24-hour, 48-hour, and 7-day samples) the filters were frozen until further analyses. In a complementary approach, soil material was collected in dust source regions in the African Sahel. These filter and soil samples are currently being used to investigate the microbial composition of the aerosols by means of genetic techniques (NGS-sequencing). We also investigate and characterize the IN properties of the filter samples utilizing filtration, thermal, chemical and enzyme treatments. Immersion freezing experiments are performed at relatively high subzero temperatures (-1 to -15˚ C) using the mono ice nucleation array (MINA). Utilizing microscopy, we want to understand the connection between biological organisms and dust particles. Cited literature: Conen, F., Morris, C.E., Leifeld, J., Yakutin, M.V., Alewell, C.: Biological residues define the ice nucleation properties of soil dust. Atmospheric Chemistry and Physics 11, 9643-9648, 2011. Fröhlich-Nowoisky, J., Kampf, C.J., Weber, B., Huffman, A., Pöhlker, C., Andreae, M.O., Lang-Yona, N., Gunthe, S.S., Elbert, W., Su, H., Hoor, P., Thines, E., Hoffmann, T., Despres, V.R., Pöschl, U.: Bioaerosols in the Earth System: Climate, Health, and Ecosystem Interactions. Atmospheric Research 182, 346-376, 2016. Prospero, J. M., Blades, E., Mathison, G., and Naidu, R.: Interhemispheric transport of viable fungi and bacteria from Africa to the Caribbean with soil dust, Aerobiologia, 21, 1-19, 2005.

Dynamic High-temperature Testing of an Iridium Alloy in Compression at High-strain Rates: Dynamic High-temperature Testing

DOE PAGES

Song, B.; Nelson, K.; Lipinski, R.; ...

2014-08-21

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-strain -rate performance are needed for understanding high-speed impacts in severe environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain -rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. In our study, we analyzed the difficulties encountered in high-temperature Kolsky bar testing of thin iridium alloy specimens in compression. We made appropriate modifications using themore » current high-temperature Kolsky bar technique in order to obtain reliable compressive stress–strain response of an iridium alloy at high-strain rates (300–10 000 s -1) and temperatures (750 and 1030°C). The compressive stress–strain response of the iridium alloy showed significant sensitivity to both strain rate and temperature.« less

Relative contributions of the fraction of unfrozen water and of salt concentration to the survival of slowly frozen human erythrocytes.

PubMed Central

Mazur, P; Rall, W F; Rigopoulos, N

1981-01-01

As suspensions of cells freeze, the electrolytes and other solutes in the external solution concentrate progressively, and the cells undergo osmotic dehydration if cooling is slow. The progressive concentration of solute comes about as increasing amounts of pure ice precipitate out of solution and cause the liquid-filled channels in which the cells are sequestered to dwindle in size. The consensus has been that slow freezing injury is related to the composition of the solution in these channels and not to the amount of residual liquid. The purpose of the research reported here was to test this assumption on human erythrocytes. Ordinarily, solute concentration and the amount of liquid in the unfrozen channels are inversely coupled. To vary them independently, one must vary the initial solute concentration. Two solutes were used here: NaCl and the permeating protective additive glycerol. To vary the total initial solute concentration while holding the mass ratio of glycerol to NaCl constant, we had to allow the NaCl tonicity to depart from isotonic. Specifically, human red cells were suspended in solutions with weight ratios of glycerol to NaCl of either 5.42 or 11.26, where the concentrations of NaCl were 0.6, 0.75, 1.0, 2.0, 3.0, or 4.0 times isotonic. Samples were then frozen to various subzero temperatures, which were chosen to produce various molalities of NaCl (0.24-3.30) while holding the fraction of unfrozen water constant, or conversely to produce various unfrozen fractions (0.03-0.5) while holding the molality of salt constant. (Not all combinations of these values were possible). The following general findings emerged: (a) few cells survived the freezing of greater than 90% of the extracellular water regardless of the salt concentration in the residual unfrozen portion. (b) When the fraction of frozen water was less than 75% the majority of the cells survived even when the salt concentration in the unfrozen portion exceeded 2 molal. (c) Salt concentration affected survival significantly only when the frozen fraction lay between 75 and 90%. To find a major effect on survival of the fraction of water that remains unfrozen was unexpected. It may require major modifications in how cryobiologists view solution-effect injury and its prevention. PMID:7326328

Testing the effects of temperature and humidity on printed passive UHF RFID tags on paper substrate

NASA Astrophysics Data System (ADS)

Linnea Merilampi, Sari; Virkki, Johanna; Ukkonen, Leena; Sydänheimo, Lauri

2014-05-01

This article is an interesting substrate material for environmental-friendly printable electronics. In this study, screen-printed RFID tags on paper substrate are examined. Their reliability was tested with low temperature, high temperature, slow temperature cycling, high temperature and high humidity and water dipping test. Environmental stresses affect the tag antenna impedance, losses and radiation characteristics due to their impact on the ink film and paper substrate. Low temperature, temperature cycling and high humidity did not have a radical effect on the measured parameters: threshold power, backscattered signal power or read range of the tags. However, the frequency response and the losses of the tags were slightly affected. Exposure to high temperature was found to even improve the tag performance due to the positive effect of high temperature on the ink film. The combined high humidity and high temperature had the most severe effect on the tag performance. The threshold power increased, backscattered power decreased and the read range was shortened. On the whole, the results showed that field use of these tags in high, low and changing temperature conditions and high humidity conditions is possible. Use of these tags in combined high-humidity and high-temperature conditions should be carefully considered.

Ultrasonic Al₂O₃ Ceramic Thermometry in High-Temperature Oxidation Environment.

PubMed

Wei, Yanlong; Gao, Yubin; Xiao, Zhaoqian; Wang, Gao; Tian, Miao; Liang, Haijian

2016-11-11

In this study, an ultrasonic temperature measurement system was designed with Al₂O₃ high-temperature ceramic as an acoustic waveguide sensor and preliminarily tested in a high-temperature oxidation environment. The test results indicated that the system can indeed work stably in high-temperature environments. The relationship between the temperature and delay time of 26 °C-1600 °C ceramic materials was also determined in order to fully elucidate the high-temperature oxidation of the proposed waveguide sensor and to lay a foundation for the further application of this system in temperatures as high as 2000 °C.

High-temperature responses of North American cacti

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, S.D.; Didden-Zopfy, B.; Nobel, P.S.

1984-04-01

High-temperature tolerances of 14 species of North American cacti were investigated. A reduction in the proportion of chlorenchyma cells taking up a vital stain (neutral red) and reduced nocturnal acid accumulation were used as indicators of high-temperature damage. All species tolerated relatively high tissue temperatures, the mean maximum tolerance being 64/sup 0/C, with an absolute maximum of 69/sup 0/ for two species of ferocactus. Such tissue tolerances to high temperature may be unsurpassed in vascular plants. Morphological features can affect tissue temperatures. Specifically, thin-stemmed species such as the cylindropuntias attain lower maximum temperatures under identical microclimatic conditions than do moremore » massive species; they also tend to be less tolerant of high-temperature stress. Stem diameter changes of three species of columnar ceriod cacti along a Sonoran Desert latitudinal transect were previously attributed to adaptation to progressively colder temperatures northward. Such changes can also be interpreted as a morphological adaptation to high temperatures, particularly in the southern Sonoran Desert. Interspecific differences in high-temperature tolerance may account for distributional differences among other species. Acclimation of high-temperature tolerances in response to increasing day/night air temperatures was observed in all 14 species, especially at higher growh temperatures. From 40/sup 0/ day/30/sup 0/ night to 50/sup 0//40/sup 0/, the tolerable tissue temperatures increased an average of 6/sup 0/. Half-times for the acclimation shifts were 1-3d. Although cacti attain extremely high tissue temperatures in desert habitats, tolerance of high temperatures and pronounced acclimation potential allow them to occur in some of the hottest habitats in North America.« less

Effect of In-situ Cure on Measurement of Glass Transition Temperatures in High-temperature Thermosetting Polymers

DTIC Science & Technology

2015-01-01

TEMPERATURES IN HIGH-TEMPERATURE THERMOSETTING POLYMERS 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...illustrated the difficulties inherent in measurement of the glass transition temperature of this high-temperature thermosetting polymer via dynamic...copyright protection in the United States. EFFECT OF IN-SITU CURE ON MEASUREMENT OF GLASS TRANSITION TEMPERATURES IN HIGH-TEMPERATURE THERMOSETTING

High-Temperature Piezoelectric Sensing

PubMed Central

Jiang, Xiaoning; Kim, Kyungrim; Zhang, Shujun; Johnson, Joseph; Salazar, Giovanni

2014-01-01

Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented. PMID:24361928

Anther response to high-temperature stress during development and pollen thermotolerance heterosis as revealed by pollen tube growth and in vitro pollen vigor analysis in upland cotton.

PubMed

Song, Guicheng; Wang, Miaomiao; Zeng, Bin; Zhang, Jing; Jiang, Chenliang; Hu, Qirui; Geng, Guangtao; Tang, Canming

2015-05-01

Pollen tube growth in styles was strongly inhibited by temperature above 35 °C, and the yield of cotton decreased because of the adverse effect of high temperatures during square development. High-temperature stress during flowering influences the square development of upland cotton (Gossypium hirsutum L.) and cotton yield. Although it is well known that square development is sensitive to high temperature, high-temperature sensitive stages of square development and the effects of high temperature on pollen tube growth in the styles are unknown. The effect of high temperature on anther development corresponding to pollen vigor is unknown during anther development. The objectives of this study were to identify the stages of square development that are sensitive to high temperatures (37/30 and 40/34 °C), to determine whether the abnormal development of squares influenced by high temperature is responsible for the variation in the in vitro germination percent of pollen grains at anthesis, to identify the effect of high temperature on pollen germination in the styles, and to determine pollen thermotolerance heterosis. Our results show that the stages from the sporogenous cell to tetrad stage (square length <6.0 mm) were the most sensitive to high temperature, and the corresponding pollen viability at anthesis was consistent with the changes in the square development stage. Pollen tube growth in the styles was strongly inhibited by temperature above 35 °C, and the yield of cotton decreased because of the effect of high temperature during square development. The thermotolerance of hybrid F1 pollen showed heterosis, and pollen viability could be used as a criterion for screening for high-temperature tolerance cultivars. These results can be used in breeding to develop new cotton cultivars that can withstand high-temperature conditions, particularly in a future warmer climate.

Body temperature and resistance to evaporative water loss in tropical Australian frogs.

PubMed

Tracy, Christopher R; Christian, Keith A; Betts, Gregory; Tracy, C Richard

2008-06-01

Although the skin of most amphibians measured to date offers no resistance to evaporative water loss (EWL), some species, primarily arboreal frogs, produce skin secretions that increase resistance to EWL. At high air temperatures, it may be advantageous for amphibians to increase EWL as a means to decrease body temperature. In Australian hylid frogs, most species do not decrease their resistance at high air temperature, but some species with moderate resistance (at moderate air temperatures) gradually decrease resistance with increasing air temperature, and some species with high resistance (at moderate air temperatures) abruptly decrease resistance at high air temperatures. Lower skin resistance at high air temperatures decreases the time to desiccation, but the lower body temperatures allow the species to avoid their critical thermal maximum (CT(Max)) body temperatures. The body temperatures of species with low to moderate resistances to EWL that do not adjust resistance at high air temperatures do not warm to their CT(Max), although for some species, this is because they have high CT(Max) values. As has been reported previously for resistance to EWL generally, the response pattern of change of EWL at high air temperatures has apparently evolved independently among Australian hylids. The mechanisms involved in causing resistance and changes in resistance are unknown.

Effects of high temperature after pollination on physicochemical properties of waxy maize flour during grain development.

PubMed

Lu, Dalei; Cai, Xuemei; Yan, Fabao; Sun, Xuli; Wang, Xin; Lu, Weiping

2014-05-01

Waxy maize is grown in South China, where high temperatures frequently prevail. The effect of high-temperature stress on grain development of waxy maize is not known. High temperature decreased the grain fresh weight and volume, and lowered the grain dry weight and water content after 22 days after pollination (DAP). Plants exposed to high temperature had low starch content, and high protein and soluble sugar contents at maturity. Starch iodine binding capacity and granule size were increased by heat stress at all grain-filling stages. The former parameter decreased, while the latter parameter increased gradually with grain development. High temperature increased the peak and breakdown viscosity before 30 DAP, but the value decreased at maturity. Pasting and gelatinization temperatures at different stages were increased by heat stress and gradually decreased with grain development under both high-temperature and control conditions. Gelatinization enthalpy increased initially but decreased after peaking at 22 DAP under both control and heat stress conditions. High temperature decreased gelatinization enthalpy after 10 DAP. Retrogradation percentage value increased with high temperature throughout grain development. High temperature after pollination changes the dynamics of grain filling of waxy maize, which may underlie the observed changes in its pasting and thermal properties. © 2013 Society of Chemical Industry.

The Analysis and Modeling of Phase Stability and Multiphase Designs in High Temperature Refractory Metal-Silicon-Boron Alloys

DTIC Science & Technology

2009-01-27

high temperature mechanical properties , it was confirmed that the three phase eutectic structure exhibited exceptionally high strength and creep...microstructurc constituent, offer an attractive property balance of high melting temperature, oxidation resistance and useful high temperature mechanical ...design of new multiphase high-temperature alloys with balanced environmental and mechanical properties . 15. SUBJECT TERMS Phase Stability, Alloying

Decreased photosynthetic rate under high temperature in wheat is due to lipid desaturation, oxidation, acylation, and damage of organelles.

PubMed

Djanaguiraman, M; Boyle, D L; Welti, R; Jagadish, S V K; Prasad, P V V

2018-04-05

High temperature is a major abiotic stress that limits wheat (Triticum aestivum L.) productivity. Variation in levels of a wide range of lipids, including stress-related molecular species, oxidative damage, cellular organization and ultrastructural changes were analyzed to provide an integrated view of the factors that underlie decreased photosynthetic rate under high temperature stress. Wheat plants of cultivar Chinese Spring were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of the booting stage. Thereafter, plants were exposed to high temperature (35/25 °C) for 16 d. Compared with optimum temperature, a lower photosynthetic rate was observed at high temperature which is an interplay between thylakoid membrane damage, thylakoid membrane lipid composition, oxidative damage of cell organelle, and stomatal and non-stomatal limitations. Triacylglycerol levels were higher under high temperature stress. Polar lipid fatty acyl unsaturation was lower at high temperature, while triacylglycerol unsaturation was the same at high temperature and optimum temperature. The changes in lipid species indicates increases in activities of desaturating, oxidizing, glycosylating and acylating enzymes under high temperature stress. Cumulative effect of high temperature stress led to generation of reactive oxygen species, cell organelle and membrane damage, and reduced antioxidant enzyme activity, and imbalance between reactive oxygen species and antioxidant defense system. Taken together with recent findings demonstrating that reactive oxygen species are formed from and are removed by thylakoid lipids, the data suggest that reactive oxygen species production, reactive oxygen species removal, and changes in lipid metabolism contribute to decreased photosynthetic rate under high temperature stress.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Bo; Nelson, Kevin; Jin, Helena

Iridium alloys have been utilized as structural materials for certain high-temperature applications, due to their superior strength and ductility at elevated temperatures. The mechanical properties, including failure response at high strain rates and elevated temperatures of the iridium alloys need to be characterized to better understand high-speed impacts at elevated temperatures. A DOP-26 iridium alloy has been dynamically characterized in compression at elevated temperatures with high-temperature Kolsky compression bar techniques. However, the dynamic high-temperature compression tests were not able to provide sufficient dynamic high-temperature failure information of the iridium alloy. In this study, we modified current room-temperature Kolsky tension barmore » techniques for obtaining dynamic tensile stress-strain curves of the DOP-26 iridium alloy at two different strain rates (~1000 and ~3000 s-1) and temperatures (~750°C and ~1030°C). The effects of strain rate and temperature on the tensile stress-strain response of the iridium alloy were determined. The DOP-26 iridium alloy exhibited high ductility in stress-strain response that strongly depended on both strain rate and temperature.« less

Molecular cloning, sequence analysis and homology modeling of the first caudata amphibian antifreeze-like protein in axolotl (Ambystoma mexicanum).

PubMed

Zhang, Songyan; Gao, Jiuxiang; Lu, Yiling; Cai, Shasha; Qiao, Xue; Wang, Yipeng; Yu, Haining

2013-08-01

Antifreeze proteins (AFPs) refer to a class of polypeptides that are produced by certain vertebrates, plants, fungi, and bacteria and which permit their survival in subzero environments. In this study, we report the molecular cloning, sequence analysis and three-dimensional structure of the axolotl antifreeze-like protein (AFLP) by homology modeling of the first caudate amphibian AFLP. We constructed a full-length spleen cDNA library of axolotl (Ambystoma mexicanum). An EST having highest similarity (∼42%) with freeze-responsive liver protein Li16 from Rana sylvatica was identified, and the full-length cDNA was subsequently obtained by RACE-PCR. The axolotl antifreeze-like protein sequence represents an open reading frame for a putative signal peptide and the mature protein composed of 93 amino acids. The calculated molecular mass and the theoretical isoelectric point (pl) of this mature protein were 10128.6 Da and 8.97, respectively. The molecular characterization of this gene and its deduced protein were further performed by detailed bioinformatics analysis. The three-dimensional structure of current AFLP was predicted by homology modeling, and the conserved residues required for functionality were identified. The homology model constructed could be of use for effective drug design. This is the first report of an antifreeze-like protein identified from a caudate amphibian.

A Eu/Tb-mixed MOF for luminescent high-temperature sensing

NASA Astrophysics Data System (ADS)

Wang, Huizhen; Zhao, Dian; Cui, Yuangjing; Yang, Yu; Qian, Guodong

2017-02-01

Temperature measurements and thermal mapping using luminescent MOF operating in the high-temperature range are of great interest in the micro-electronic diagnosis. In this paper, we report a thermostable Eu/Tb-mixed MOF Eu0.37Tb0.63-BTC-a exhibiting strong luminescence at elevated temperature, which can serve as a ratiometric luminescent thermometer for high-temperature range. The high-temperature operating range (313-473 K), high relative sensitivity and accurate temperature resolution, make such a Eu/Tb-mixed MOF useful for micro-electronic diagnosis.

Community Proteogenomics of a Cold-methane Seep Sediment at Nyegga, Mid-Norwegian Margin

NASA Astrophysics Data System (ADS)

Stokke, R.; Roalkvam, I.; Lanzen, A.; Chen, Y.; Haflidason, H.; Steen, I.

2010-12-01

Anaerobic oxidation of methane (AOM) is limited to anoxic environments and differs in its rates from a few pmol cm-3day-1 in subsurface SMTZ (sulfate-methane transition zone) of deep margins, to a few μmol cm-3 day-1 in surface sediments above gas hydrates [1]. This process is catalyzed by consortia of anaerobic methane oxidizing archaea (ANME) in association with sulfate-reducing bacteria. The Nyegga area is located on the Mid-Norwegian continental slope at the northern flank of the Storegga Slide at 700-800 mbsl. Hundreds of pockmarks are widespread on the seabed in Nyegga and sub-zero temperatures (-0.7 °C), and pingo-structures within the pockmarks are indicators of active fluid flow locations. Preliminary microbial and geochemical profiling of a 22 cm push-core within the G11 pockmark gave strong indications of an ANME-1 dominated community at 14-16 cmbsf. In light of these findings we submitted extracted DNA to 454-pyrosequencing. Sequencing data (829,527 reads) was assembled using the Newbler v2.3, resulting in 13,151 contigs (357,530 reads) over 500 bp with the longest contig being 24,521 bp. MEGAN taxonomic analysis supported the high abundance of Euryarchaea (70%) with 66% of the assembled metagenome belonging to ANME-1. In order to obtain functional information of the ANME-1 community, protein extraction protocols from sediment samples was established. Extracted proteins was separated on a large (18cm) 1D-SDS-PAGE and subsequently cut in 30 gel slices. Peptides extracted after In-gel tryptic digest was injected into an Ultimate 3000 nanoLC system connected to a linear quadropole ion trap-orbitrap (LTQ-Orbitrap XL) mass spectrometer equipped with a nanoelectrospray ion source. A custom database of open reading frames (ORFs) from the metagenome including known contaminants such as trypsin and human keratin was search against using Mascot 2.2. IRMa tool box [2] was used in peptide validation and peptides whose score >= 25.0 (i.e avg identity, p<0.05) and rank <= 1 was marked as significant. Validated protein ORFs were subjected to a local Blastp search against NCBInr with an E-value cut-off 0.001. A total of 370 proteins met the criteria with 254 of the proteins belonging to ANME-1. The protein dataset contained enzymes involved in C1-metabolism in the reverse metanogenesis pathway of ANME-1 as well as the enzymes sulfite reductase and APS-reductase (of presumably bacterial origin). Hence, the key enzymes involved in anaerobic methane oxidation were expressed in the environment. Results will be further discussed. [1] Knittel, K., and Boetius, A. (2009) Anaerobic Oxidation of Methane: Progress with an Unknown Process. Annu. Rev. Microbiol. 63, 311-334. [2] Dupierris, V., Masselon, C., Court, M., Kieffer-Jaquinod, S., and Bruley, C. (2009) A toolbox for validation of mass spectrometry peptides identification and generation of database: IRMa. Bioinformatics 25, 1980-1981.

Relative sensitivity of five Hawaiian coral species to high temperature under high-pCO2 conditions

NASA Astrophysics Data System (ADS)

Bahr, Keisha D.; Jokiel, Paul L.; Rodgers, Ku'ulei S.

2016-06-01

Coral reef ecosystems are presently undergoing decline due to anthropogenic climate change. The chief detrimental factors are increased temperature and increased pCO2. The purpose of this study was to evaluate the effect of these two stressors operating independently and in unison on the biological response of common Hawaiian reef corals. Manipulative experiments were performed using five species ( Porites compressa, Pocillopora damicornis, Fungia scutaria, Montipora capitata, and Leptastrea purpurea) in a continuous-flow mesocosm system under natural sunlight conditions. Corals were grown together as a community under treatments of high temperature (2 °C above normal maximum summer temperature), high pCO2 (twice present-day conditions), and with both factors acting in unison. Control corals were grown under present-day pCO2 and at normal summer temperatures. Leptastrea purpurea proved to be an extremely hardy coral. No change in calcification or mortality occurred under treatments of high temperature, high pCO2, or combined high temperature-high pCO2. The remaining four species showed reduced calcification in the high-temperature treatment. Two species ( L. purpurea and M. capitata) showed no response to increased pCO2. Also, high pCO2 ameliorated the negative effect of high temperature on the calcification rates of P. damicornis. Mortality was driven primarily by high temperature, with a negative synergistic effect in P. compressa only in the high-pCO2-high-temperature treatment. Results support the observation that biological response to temperature and pCO2 elevation is highly species-specific, so generalizations based on response of a single species might not apply to a diverse and complex coral reef community.

High temperature superconducting composite conductor and method for manufacturing the same

DOEpatents

Holesinger, Terry G.; Bingert, John F.

2002-01-01

A high temperature superconducting composite conductor is provided including a high temperature superconducting material surrounded by a noble metal layer, the high temperature superconducting composite conductor characterized as having a fill factor of greater than about 40. Additionally, the conductor can be further characterized as containing multiple cores of high temperature superconducting material surrounded by a noble metal layer, said multiple cores characterized as having substantially uniform geometry in the cross-sectional dimensions. Processes of forming such a high temperature superconducting composite conductor are also provided.

[Multi-temporal scale analysis of impacts of extreme high temperature on net carbon uptake in subtropical coniferous plantation.

PubMed

Zhang, Mi; Wen, Xue Fa; Zhang, Lei Ming; Wang, Hui Min; Guo, Yi Wen; Yu, Gui Rui

2018-02-01

Extreme high temperature is one of important extreme weathers that impact forest ecosystem carbon cycle. In this study, applying CO 2 flux and routine meteorological data measured during 2003-2012, we examined the impacts of extreme high temperature and extreme high temperature event on net carbon uptake of subtropical coniferous plantation in Qianyanzhou. Combining with wavelet analysis, we analyzed environmental controls on net carbon uptake at different temporal scales, when the extreme high temperature and extreme high temperature event happened. The results showed that mean daily cumulative NEE decreased by 51% in the days with daily maximum air temperature range between 35 ℃ and 40 ℃, compared with that in the days with the range between 30 ℃ and 34 ℃. The effects of the extreme high temperature and extreme high temperature event on monthly NEE and annual NEE related to the strength and duration of extreme high tempe-rature event. In 2003, when strong extreme high temperature event happened, the sum of monthly cumulative NEE in July and August was only -11.64 g C·m -2 ·(2 month) -1 . The value decreased by 90%, compared with multi-year average value. At the same time, the relative variation of annual NEE reached -6.7%. In July and August, when the extreme high temperature and extreme high temperature event occurred, air temperature (T a ) and vapor press deficit (VPD) were the dominant controller for the daily variation of NEE. The coherency between NEE T a and NEE VPD was 0.97 and 0.95, respectively. At 8-, 16-, and 32-day periods, T a , VPD, soil water content at 5 cm depth (SWC), and precipitation (P) controlled NEE. The coherency between NEE SWC and NEE P was higher than 0.8 at monthly scale. The results indicated that atmospheric water deficit impacted NEE at short temporal scale, when the extreme high temperature and extreme high temperature event occurred, both of atmospheric water deficit and soil drought stress impacted NEE at long temporal scales in this ecosystem.

Economic status and temperature-related mortality in Asia

NASA Astrophysics Data System (ADS)

Lim, Youn-Hee; Bell, Michelle L.; Kan, Haidong; Honda, Yasushi; Guo, Yue-Liang Leon; Kim, Ho

2015-10-01

In developed countries, low latitude and high temperature are positively associated with the population's ability to adapt to heat. However, few studies have examined the effect of economic status on the relationship between long-term exposure to high temperature and health. We compared heterogeneous temperature-related mortality effects relative to the average summer temperature in high-socioeconomic-status (SES) cities to temperature-related effects in low-SES cities. In the first stage of the research, we conducted a linear regression analysis to quantify the mortality effects of high temperature (at or above the 95th percentile) in 32 cities in Taiwan, China, Japan, and Korea. In the second stage, we used a meta-regression to examine the association between mortality risk with average summer temperature and gross domestic product (GDP) per capita. In cities with a low GDP per capita (less than 20,000 USD), the effects of temperature were detrimental to the population if the long-term average summer temperature was high. In contrast, in cities with a high GDP per capita, temperature-related mortality risk was not significantly related to average summer temperature. The relationship between long-term average summer temperature and the short-term effects of high temperatures differed based on the city-level economic status.

Responses of Rapid Viscoanalyzer Profile and Other Rice Grain Qualities to Exogenously Applied Plant Growth Regulators under High Day and High Night Temperatures

PubMed Central

Fahad, Shah; Hussain, Saddam; Saud, Shah; Hassan, Shah; Chauhan, Bhagirath Singh; Khan, Fahad; Ihsan, Muhammad Zahid; Ullah, Abid; Wu, Chao; Bajwa, Ali Ahsan; Alharby, Hesham; Amanullah; Nasim, Wajid; Shahzad, Babar; Tanveer, Mohsin; Huang, Jianliang

2016-01-01

High-temperature stress degrades the grain quality of rice; nevertheless, the exogenous application of plant growth regulators (PGRs) might alleviate the negative effects of high temperatures. In the present study, we investigated the responses of rice grain quality to exogenously applied PGRs under high day temperatures (HDT) and high night temperatures (HNT) under controlled conditions. Four different combinations of ascorbic acid (Vc), alpha-tocopherol (Ve), brassinosteroids (Br), methyl jasmonates (MeJA) and triazoles (Tr) were exogenously applied to two rice cultivars (IR-64 and Huanghuazhan) prior to the high-temperature treatment. A Nothing applied Control (NAC) was included for comparison. The results demonstrated that high-temperature stress was detrimental for grain appearance and milling qualities and that both HDT and HNT reduced the grain length, grain width, grain area, head rice percentage and milled rice percentage but increased the chalkiness percentage and percent area of endosperm chalkiness in both cultivars compared with ambient temperature (AT). Significantly higher grain breakdown, set back, consistence viscosity and gelatinization temperature, and significantly lower peak, trough and final viscosities were observed under high-temperature stress compared with AT. Thus, HNT was more devastating for grain quality than HDT. The exogenous application of PGRs ameliorated the adverse effects of high temperature in both rice cultivars, and Vc+Ve+MejA+Br was the best combination for both cultivars under high temperature stress. PMID:27472200

Reduction of pyruvate orthophosphate dikinase activity is associated with high temperature-induced chalkiness in rice grains.

PubMed

Wang, Zhen-mei; Li, Hai-xia; Liu, Xiong-feng; He, Ying; Zeng, Han-lai

2015-04-01

Global warming affects both rice (Oryza sativa) yields and grain quality. Rice chalkiness due to high temperature during grain filling would lower the grain quality. The biochemical and molecular mechanisms responsible for the increased occurrence of chalkiness under high temperature are not fully understood. Previous research suggested that cytosolic pyruvate orthophosphate dikinase (cyPPDK, EC 2.7.9.1) in rice modulates carbon metabolism. The objective of this study was to determine the relationship between cyPPDK and high temperature-induced chalkiness. High temperature treatments were applied during the grain filling of two rice cultivars (9311 and TXZ-25) which had different sensitivity of chalkiness to high temperature. Chalkiness was increased significantly under high temperature treatment, especially for TXZ-25. A shortened grain filling duration and a decreased grain weight in both cultivars were caused by high temperature treatment. A reduction in PPDK activities due to high temperature was observed during the middle and late grain filling periods, accompanied by down regulated cyPPDK mRNA and protein levels. The temperature effects on the developmental regulation of PPDK activity were confirmed at transcription, translation and post-translational levels. PPDK activities were insensitive to variation in PPDK levels, suggesting the rapid phosphorylation mechanism of this protein. The two varieties showed similar responses to the high temperature treatment in both PPDK activities and chalkiness. We concluded that high temperature-induced chalkiness was associated with the reduction of PPDK activity. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Identification of High-Temperature-Responsive Genes in Cereals1[C][W

PubMed Central

Hemming, Megan N.; Walford, Sally A.; Fieg, Sarah; Dennis, Elizabeth S.; Trevaskis, Ben

2012-01-01

High temperature influences plant development and can reduce crop yields. We examined how ambient temperature influences reproductive development in the temperate cereals wheat (Triticum aestivum) and barley (Hordeum vulgare). High temperature resulted in rapid progression through reproductive development in long days, but inhibited early stages of reproductive development in short days. Activation of the long-day flowering response pathway through day-length-insensitive alleles of the PHOTOPERIOD1 gene, which result in high FLOWERING LOCUS T-like1 transcript levels, did not allow rapid early reproductive development at high temperature in short days. Furthermore, high temperature did not increase transcript levels of FLOWERING LOCUS T-like genes. These data suggest that genes or pathways other than the long-day response pathway mediate developmental responses to high temperature in cereals. Transcriptome analyses suggested a possible role for vernalization-responsive genes in the developmental response to high temperature. The MADS-box floral repressor HvODDSOC2 is expressed at elevated levels at high temperature in short days, and might contribute to the inhibition of early reproductive development under these conditions. FLOWERING PROMOTING FACTOR1-like, RNase-S-like genes, and VER2-like genes were also identified as candidates for high-temperature-responsive developmental regulators. Overall, these data suggest that rising temperatures might elicit different developmental responses in cereal crops at different latitudes or times of year, due to the interaction between temperature and day length. Additionally, we suggest that different developmental regulators might mediate the response to high temperature in cereals compared to Arabidopsis (Arabidopsis thaliana). PMID:22279145

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, B.; Nelson, K.; Lipinski, R.

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-strain -rate performance are needed for understanding high-speed impacts in severe environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain -rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. In our study, we analyzed the difficulties encountered in high-temperature Kolsky bar testing of thin iridium alloy specimens in compression. We made appropriate modifications using themore » current high-temperature Kolsky bar technique in order to obtain reliable compressive stress–strain response of an iridium alloy at high-strain rates (300–10 000 s -1) and temperatures (750 and 1030°C). The compressive stress–strain response of the iridium alloy showed significant sensitivity to both strain rate and temperature.« less

Technology Requirements and Development for Affordable High-Temperature Distributed Engine Controls

DTIC Science & Technology

2012-06-04

long lasting, high temperature modules is to use high temperature electronics on ceramic modules. The electronic components are “ brazed ” onto the...Copyright © 2012 by ISA Technology Requirements and Development for Affordable High - Temperature Distributed Engine Controls Alireza Behbahani 1...with regards to high temperature capability. The Government and Industry Distributed Engine Controls Working Group (DECWG) [5] has been established

Optimization of Multilayer Laminated Film and Absorbent of Vacuum Insulation Panel for Use at High Temperature

NASA Astrophysics Data System (ADS)

Araki, Kuninari; Echigoya, Wataru; Tsuruga, Toshimitsu; Kamoto, Daigorou; Matsuoka, Shin-Ichi

For the energy saving regulation and larger capacity, Vacuum Insulation Panel (VIP) has been used in refrigerators with urethane foam in recent years. VIP for low temperature is constructed by laminated plastic film, using heat welding of each neighboring part for keeping vacuum, so that the performance decrement is very large under high temperature. But recently high efficiency insulation material is desired for high temperature water holding devices (automatic vending machine, heat pump water heater, electric hot-water pot water, etc.), and we especially focused on cost and ability of the laminated plastic film and absorbent for high temperature VIP. We measured the heatproof temperature of plastic films and checked the amount of water vapor and out coming gas on temperature-programmed adsorption in absorbent. These results suggest the suitable laminated film and absorbent system for VIP use at high temperature, and the long-term reliability was evaluated by measuring thermal conductivity of high temperature. As a result it was found that high-retort pouch of CPP (cast polypropylene film) and adding of aluminum coating are the most suitable materials for use in the welded layers of high-temperature VIPs (105°C).

ABA-insensitive3, ABA-insensitive5, and DELLAs Interact to activate the expression of SOMNUS and other high-temperature-inducible genes in imbibed seeds in Arabidopsis.

PubMed

Lim, Soohwan; Park, Jeongmoo; Lee, Nayoung; Jeong, Jinkil; Toh, Shigeo; Watanabe, Asuka; Kim, Junghyun; Kang, Hyojin; Kim, Dong Hwan; Kawakami, Naoto; Choi, Giltsu

2013-12-01

Seeds monitor the environment to germinate at the proper time, but different species respond differently to environmental conditions, particularly light and temperature. In Arabidopsis thaliana, light promotes germination but high temperature suppresses germination. We previously reported that light promotes germination by repressing SOMNUS (SOM). Here, we examined whether high temperature also regulates germination through SOM and found that high temperature activates SOM expression. Consistent with this, som mutants germinated more frequently than the wild type at high temperature. The induction of SOM mRNA at high temperature required abscisic acid (ABA) and gibberellic acid biosynthesis, and ABA-insensitive3 (ABI3), ABI5, and DELLAs positively regulated SOM expression. Chromatin immunoprecipitation assays indicated that ABI3, ABI5, and DELLAs all target the SOM promoter. At the protein level, ABI3, ABI5, and DELLAs all interact with each other, suggesting that they form a complex on the SOM promoter to activate SOM expression at high temperature. We found that high-temperature-inducible genes frequently have RY motifs and ABA-responsive elements in their promoters, some of which are targeted by ABI3, ABI5, and DELLAs in vivo. Taken together, our data indicate that ABI3, ABI5, and DELLAs mediate high-temperature signaling to activate the expression of SOM and other high-temperature-inducible genes, thereby inhibiting seed germination.

Packaging Technology for SiC High Temperature Electronics

NASA Technical Reports Server (NTRS)

Chen, Liang-Yu; Neudeck, Philip G.; Spry, David J.; Meredith, Roger D.; Nakley, Leah M.; Beheim, Glenn M.; Hunter, Gary W.

2017-01-01

High-temperature environment operable sensors and electronics are required for long-term exploration of Venus and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500 C. A compatible packaging system is essential for long-term testing and application of high temperature electronics and sensors in relevant environments. This talk will discuss a ceramic packaging system developed for high temperature electronics, and related testing results of SiC integrated circuits at 500 C facilitated by this high temperature packaging system, including the most recent progress.

Study Progress of Physiological Responses in High Temperature Environment

NASA Astrophysics Data System (ADS)

Li, K.; Zheng, G. Z.; Bu, W. T.; Wang, Y. J.; Lu, Y. Z.

2017-10-01

Certain workers are exposed to high temperatures for a long time. Heat stress will result in a series of physiological responses, and cause adverse effects on the health and safety of workers. This paper summarizes the physiological changes of cardiovascular system, core temperature, skin temperature, water-electrolyte metabolism, alimentary system, neuroendocrine system, reaction time and thermal fatigue in high temperature environments. It can provide a theoretical guidance for labor safety in high temperature environment.

High temperature furnace

DOEpatents

Borkowski, Casimer J.

1976-08-03

A high temperature furnace for use above 2000.degree.C is provided that features fast initial heating and low power consumption at the operating temperature. The cathode is initially heated by joule heating followed by electron emission heating at the operating temperature. The cathode is designed for routine large temperature excursions without being subjected to high thermal stresses. A further characteristic of the device is the elimination of any ceramic components from the high temperature zone of the furnace.

Identification of microRNAs associated with the exogenous spermidine-mediated improvement of high-temperature tolerance in cucumber seedlings (Cucumis sativus L.).

PubMed

Wang, Ying; Guo, Shirong; Wang, Lei; Wang, Liwei; He, Xueying; Shu, Sheng; Sun, Jin; Lu, Na

2018-04-24

High-temperature stress inhibited the growth of cucumber seedlings. Foliar spraying of 1.0 mmol·L - 1 exogenous spermidine (Spd) to the sensitive cucumber cultivar 'Jinchun No. 2' grown at high-temperature (42 °C/32 °C) in an artificial climate box improved the high-temperature tolerance. Although there have been many reports on the response of microRNAs (miRNAs) to high-temperature stress, the mechanism by which exogenous Spd may mitigate the damage of high-temperature stress through miRNA-mediated regulation has not been studied. To elucidate the regulation of miRNAs in response to exogenous Spd-mediated improvement of high-temperature tolerance, four small RNA libraries were constructed from cucumber leaves and sequenced: untreated-control (CW), Spd-treated (CS), high-temperature stress (HW), and Spd-treated and high-temperature stress (HS). As a result, 107 known miRNAs and 79 novel miRNAs were identified. Eight common differentially expressed miRNAs (miR156d-3p, miR170-5p, miR2275-5p, miR394a, miR479b, miR5077, miR5222 and miR6475) were observed in CS/CW, HW/CW, HS/CW and HS/HW comparison pairs, which were the first set of miRNAs that responded to not only high-temperature stress but also exogenous Spd in cucumber seedlings. Five of the eight miRNAs were predicted to target 107 potential genes. Gene function and pathway analyses highlighted the integral role that these miRNAs and target genes probably play in the improvement of the high-temperature tolerance of cucumber seedlings through exogenous Spd application. Our study identified the first set of miRNAs associated with the exogenous Spd-mediated improvement of high-temperature tolerance in cucumber seedlings. The results could help to promote further studies on the complex molecular mechanisms underlying high-temperature tolerance in cucumber and provide a theoretical basis for the high-quality and efficient cultivation of cucumber with high-temperature resistance.

High Temperature Chemistry at NASA: Hot Topics

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.

2014-01-01

High Temperature issues in aircraft engines Hot section: Ni and Co based Superalloys Oxidation and Corrosion (Durability) at high temperatures. Thermal protection system (TPS) and RCC (Reinforced Carbon-Carbon) on the Space Shuttle Orbiter. High temperatures in other worlds: Planets close to their stars.

High-temperature testing of high performance fiber reinforced concrete

NASA Astrophysics Data System (ADS)

Fořt, Jan; Vejmelková, Eva; Pavlíková, Milena; Trník, Anton; Čítek, David; Kolísko, Jiří; Černý, Robert; Pavlík, Zbyšek

2016-06-01

The effect of high-temperature exposure on properties of High Performance Fiber Reinforced Concrete (HPFRC) is researched in the paper. At first, reference measurements are done on HPFRC samples without high-temperature loading. Then, the HPFRC samples are exposed to the temperatures of 200, 400, 600, 800, and 1000 °C. For the temperature loaded samples, measurement of residual mechanical and basic physical properties is done. Linear thermal expansion coefficient as function of temperature is accessed on the basis of measured thermal strain data. Additionally, simultaneous difference scanning calorimetry (DSC) and thermogravimetry (TG) analysis is performed in order to observe and explain material changes at elevated temperature. It is found that the applied high temperature loading significantly increases material porosity due to the physical, chemical and combined damage of material inner structure, and negatively affects also the mechanical strength. Linear thermal expansion coefficient exhibits significant dependence on temperature and changes of material structure. The obtained data will find use as input material parameters for modelling the damage of HPFRC structures exposed to the fire and high temperature action.

Low temperature superconductor and aligned high temperature superconductor magnetic dipole system and method for producing high magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Ramesh; Scanlan, Ronald; Ghosh, Arup K.

A dipole-magnet system and method for producing high-magnetic-fields, including an open-region located in a radially-central-region to allow particle-beam transport and other uses, low-temperature-superconducting-coils comprised of low-temperature-superconducting-wire located in radially-outward-regions to generate high magnetic-fields, high-temperature-superconducting-coils comprised of high-temperature-superconducting-tape located in radially-inward-regions to generate even higher magnetic-fields and to reduce erroneous fields, support-structures to support the coils against large Lorentz-forces, a liquid-helium-system to cool the coils, and electrical-contacts to allow electric-current into and out of the coils. The high-temperature-superconducting-tape may be comprised of bismuth-strontium-calcium-copper-oxide or rare-earth-metal, barium-copper-oxide (ReBCO) where the rare-earth-metal may be yttrium, samarium, neodymium, or gadolinium. Advantageously, alignment of themore » large-dimension of the rectangular-cross-section or curved-cross-section of the high-temperature-superconducting-tape with the high-magnetic-field minimizes unwanted erroneous magnetic fields. Alignment may be accomplished by proper positioning, tilting the high-temperature-superconducting-coils, forming the high-temperature-superconducting-coils into a curved-cross-section, placing nonconducting wedge-shaped-material between windings, placing nonconducting curved-and-wedge-shaped-material between windings, or by a combination of these techniques.« less

Low to moderate temperature nanolaminate heater

DOEpatents

Eckels, J Del [Livermore, CA; Nunes, Peter J [Danville, CA; Simpson, Randall L [Livermore, CA; Hau-Riege, Stefan [Fremont, CA; Walton, Chris [Oakland, CA; Carter, J Chance [Livermore, CA; Reynolds, John G [San Ramon, CA

2011-01-11

A low to moderate temperature heat source comprising a high temperature energy source modified to output low to moderate temperatures wherein the high temperature energy source modified to output low to moderate temperatures is positioned between two thin pieces to form a close contact sheath. In one embodiment the high temperature energy source modified to output low to moderate temperatures is a nanolaminate multilayer foil of reactive materials that produces a heating level of less than 200.degree. C.

Hydrogen Production from Nuclear Energy via High Temperature Electrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

James E. O'Brien; Carl M. Stoots; J. Stephen Herring

2006-04-01

This paper presents the technical case for high-temperature nuclear hydrogen production. A general thermodynamic analysis of hydrogen production based on high-temperature thermal water splitting processes is presented. Specific details of hydrogen production based on high-temperature electrolysis are also provided, including results of recent experiments performed at the Idaho National Laboratory. Based on these results, high-temperature electrolysis appears to be a promising technology for efficient large-scale hydrogen production.

Separating heat stress from moisture stress: analyzing yield response to high temperature in irrigated maize

NASA Astrophysics Data System (ADS)

Carter, Elizabeth K.; Melkonian, Jeff; Riha, Susan J.; Shaw, Stephen B.

2016-09-01

Several recent studies have indicated that high air temperatures are limiting maize (Zea mays L.) yields in the US Corn Belt and project significant yield losses with expected increases in growing season temperatures. Further work has suggested that high air temperatures are indicative of high evaporative demand, and that decreases in maize yields which correlate to high temperatures and vapor pressure deficits (VPD) likely reflect underlying soil moisture limitations. It remains unclear whether direct high temperature impacts on yields, independent of moisture stress, can be observed under current temperature regimes. Given that projected high temperature and moisture may not co-vary the same way as they have historically, quantitative analyzes of direct temperature impacts are critical for accurate yield projections and targeted mitigation strategies under shifting temperature regimes. To evaluate yield response to above optimum temperatures independent of soil moisture stress, we analyzed climate impacts on irrigated maize yields obtained from the National Corn Growers Association (NCGA) corn yield contests for Nebraska, Kansas and Missouri. In irrigated maize, we found no evidence of a direct negative impact on yield by daytime air temperature, calculated canopy temperature, or VPD when analyzed seasonally. Solar radiation was the primary yield-limiting climate variable. Our analyses suggested that elevated night temperature impacted yield by increasing rates of phenological development. High temperatures during grain-fill significantly interacted with yields, but this effect was often beneficial and included evidence of acquired thermo-tolerance. Furthermore, genetics and management—information uniquely available in the NCGA contest data—explained more yield variability than climate, and significantly modified crop response to climate. Thermo-acclimation, improved genetics and changes to management practices have the potential to partially or completely offset temperature-related yield losses in irrigated maize.

High-temperature microphone system. [for measuring pressure fluctuations in gases at high temperature

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J. (Inventor)

1979-01-01

Pressure fluctuations in air or other gases in an area of elevated temperature are measured using a condenser microphone located in the area of elevated temperature and electronics for processing changes in the microphone capacitance located outside the area the area and connected to the microphone by means of high-temperature cable assembly. The microphone includes apparatus for decreasing the undesirable change in microphone sensitivity at high temperatures. The high temperature cable assembly operates as a half-wavelength transmission line in an AM carrier system and maintains a large temperature gradient between the two ends of the cable assembly. The processing electronics utilizes a voltage controlled oscillator for automatic tuning thereby increasing the sensitivity of the measuring apparatus.

Passive Resistor Temperature Compensation for a High-Temperature Piezoresistive Pressure Sensor.

PubMed

Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Li, Wangwang; Zhang, Diya; Xiong, Jijun

2016-07-22

The main limitation of high-temperature piezoresistive pressure sensors is the variation of output voltage with operating temperature, which seriously reduces their measurement accuracy. This paper presents a passive resistor temperature compensation technique whose parameters are calculated using differential equations. Unlike traditional experiential arithmetic, the differential equations are independent of the parameter deviation among the piezoresistors of the microelectromechanical pressure sensor and the residual stress caused by the fabrication process or a mismatch in the thermal expansion coefficients. The differential equations are solved using calibration data from uncompensated high-temperature piezoresistive pressure sensors. Tests conducted on the calibrated equipment at various temperatures and pressures show that the passive resistor temperature compensation produces a remarkable effect. Additionally, a high-temperature signal-conditioning circuit is used to improve the output sensitivity of the sensor, which can be reduced by the temperature compensation. Compared to traditional experiential arithmetic, the proposed passive resistor temperature compensation technique exhibits less temperature drift and is expected to be highly applicable for pressure measurements in harsh environments with large temperature variations.

Passive Resistor Temperature Compensation for a High-Temperature Piezoresistive Pressure Sensor

PubMed Central

Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Li, Wangwang; Zhang, Diya; Xiong, Jijun

2016-01-01

The main limitation of high-temperature piezoresistive pressure sensors is the variation of output voltage with operating temperature, which seriously reduces their measurement accuracy. This paper presents a passive resistor temperature compensation technique whose parameters are calculated using differential equations. Unlike traditional experiential arithmetic, the differential equations are independent of the parameter deviation among the piezoresistors of the microelectromechanical pressure sensor and the residual stress caused by the fabrication process or a mismatch in the thermal expansion coefficients. The differential equations are solved using calibration data from uncompensated high-temperature piezoresistive pressure sensors. Tests conducted on the calibrated equipment at various temperatures and pressures show that the passive resistor temperature compensation produces a remarkable effect. Additionally, a high-temperature signal-conditioning circuit is used to improve the output sensitivity of the sensor, which can be reduced by the temperature compensation. Compared to traditional experiential arithmetic, the proposed passive resistor temperature compensation technique exhibits less temperature drift and is expected to be highly applicable for pressure measurements in harsh environments with large temperature variations. PMID:27455271

Climate Change: A New Metric to Measure Changes in the Frequency of Extreme Temperatures using Record Data

NASA Technical Reports Server (NTRS)

Munasinghe, L.; Jun, T.; Rind, D. H.

2012-01-01

Consensus on global warming is the result of multiple and varying lines of evidence, and one key ramification is the increase in frequency of extreme climate events including record high temperatures. Here we develop a metric- called "record equivalent draws" (RED)-based on record high (low) temperature observations, and show that changes in RED approximate changes in the likelihood of extreme high (low) temperatures. Since we also show that this metric is independent of the specifics of the underlying temperature distributions, RED estimates can be aggregated across different climates to provide a genuinely global assessment of climate change. Using data on monthly average temperatures across the global landmass we find that the frequency of extreme high temperatures increased 10-fold between the first three decades of the last century (1900-1929) and the most recent decade (1999-2008). A more disaggregated analysis shows that the increase in frequency of extreme high temperatures is greater in the tropics than in higher latitudes, a pattern that is not indicated by changes in mean temperature. Our RED estimates also suggest concurrent increases in the frequency of both extreme high and extreme low temperatures during 2002-2008, a period when we observe a plateauing of global mean temperature. Using daily extreme temperature observations, we find that the frequency of extreme high temperatures is greater in the daily minimum temperature time-series compared to the daily maximum temperature time-series. There is no such observable difference in the frequency of extreme low temperatures between the daily minimum and daily maximum.

ABA-INSENSITIVE3, ABA-INSENSITIVE5, and DELLAs Interact to Activate the Expression of SOMNUS and Other High-Temperature-Inducible Genes in Imbibed Seeds in Arabidopsis[W

PubMed Central

Lim, Soohwan; Park, Jeongmoo; Lee, Nayoung; Jeong, Jinkil; Toh, Shigeo; Watanabe, Asuka; Kim, Junghyun; Kang, Hyojin; Kim, Dong Hwan; Kawakami, Naoto; Choi, Giltsu

2013-01-01

Seeds monitor the environment to germinate at the proper time, but different species respond differently to environmental conditions, particularly light and temperature. In Arabidopsis thaliana, light promotes germination but high temperature suppresses germination. We previously reported that light promotes germination by repressing SOMNUS (SOM). Here, we examined whether high temperature also regulates germination through SOM and found that high temperature activates SOM expression. Consistent with this, som mutants germinated more frequently than the wild type at high temperature. The induction of SOM mRNA at high temperature required abscisic acid (ABA) and gibberellic acid biosynthesis, and ABA-INSENSITIVE3 (ABI3), ABI5, and DELLAs positively regulated SOM expression. Chromatin immunoprecipitation assays indicated that ABI3, ABI5, and DELLAs all target the SOM promoter. At the protein level, ABI3, ABI5, and DELLAs all interact with each other, suggesting that they form a complex on the SOM promoter to activate SOM expression at high temperature. We found that high-temperature-inducible genes frequently have RY motifs and ABA-responsive elements in their promoters, some of which are targeted by ABI3, ABI5, and DELLAs in vivo. Taken together, our data indicate that ABI3, ABI5, and DELLAs mediate high-temperature signaling to activate the expression of SOM and other high-temperature-inducible genes, thereby inhibiting seed germination. PMID:24326588

High-Temperature Resistance Strain Gauges

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen

1994-01-01

Resistance strain gauges developed for use at high temperatures in demanding applications like testing aircraft engines and structures. Measures static strains at temperatures up to 800 degrees C. Small and highly reproducible. Readings corrected for temperature within small tolerances, provided temperatures measured simultaneously by thermocouples or other suitable devices. Connected in wheatstone bridge.

Refractory thermowell for continuous high temperature measurement of molten metal

DOEpatents

Thiesen, Todd J.

1992-01-01

An apparatus for the continuous high temperature measurement of materials in vessels lined with rammed or cast refractory materials. A refractory housing member is integral with the refractory lining of the vessel and contains a plurality of high temperature sensing means, such as thermocouples. A face of the housing is flush with the refractory lining and contacts the high temperature material contained in the vessel. Continuous temperature measurement is achieved by a means which is coupled to the thermocouples for indicating the temperature.

HIGH-TEMPERATURE AND HIGH-PRESSURE PARTICULATE CONTROL REQUIREMENTS

EPA Science Inventory

The report reviews and evaluates high-temperature and high-pressure particulate cleanup requirements of existing and proposed energy processes. The study's aims are to define specific high-temperature and high-pressure particle removal problems, to indicate potential solutions, a...

High-temperature langatate elastic constants and experimental validation up to 900 degrees C.

PubMed

Davulis, Peter M; da Cunha, Mauricio Pereira

2010-01-01

This paper reports on a set of langatate (LGT) elastic constants extracted from room temperature to 1100 degrees C using resonant ultrasound spectroscopy techniques and an accompanying assessment of these constants at high temperature. The evaluation of the constants employed SAW device measurements from room temperature to 900 degrees C along 6 different LGT wafer orientations. Langatate parallelepipeds and wafers were aligned, cut, ground, and polished, and acoustic wave devices were fabricated at the University of Maine facilities along specific orientations for elastic constant extraction and validation. SAW delay lines were fabricated on LGT wafers prepared at the University of Maine using 100-nm platinumrhodium- zirconia electrodes capable of withstanding temperatures up to 1000 degrees C. The numerical predictions based on the resonant ultrasound spectroscopy high-temperature constants were compared with SAW phase velocity, fractional frequency variation, and temperature coefficients of delay extracted from SAW delay line frequency response measurements. In particular, the difference between measured and predicted fractional frequency variation is less than 2% over the 25 degrees C to 900 degrees C temperature range and within the calculated and measured discrepancies. Multiple temperature-compensated orientations at high temperature were predicted and verified in this paper: 4 of the measured orientations had turnover temperatures (temperature coefficient of delay = 0) between 200 and 420 degrees C, and 2 had turnover temperatures below 100 degrees C. In summary, this work reports on extracted high-temperature elastic constants for LGT up to 1100 degrees C, confirmed the validity of those constants by high-temperature SAW device measurements up to 900 degrees C, and predicted and identified temperature-compensated LGT orientations at high temperature.

Consecutive record-breaking high temperatures marked the handover from hiatus to accelerated warming

PubMed Central

Su, Jingzhi; Zhang, Renhe; Wang, Huijun

2017-01-01

Closely following the hiatus warming period, two astonishing high temperature records reached in 2014 and 2015 consecutively. To investigate the occurrence features of record-breaking high temperatures in recent years, a new index focusing the frequency of the top 10 high annual mean temperatures was defined in this study. Analyses based on this index shown that record-breaking high temperatures occurred over most regions of the globe with a salient increasing trend after 1960 s, even during the so-called hiatus period. Overlapped on the ongoing background warming trend and the interdecadal climate variabilities, the El Niño events, particularly the strong ones, can make a significant contribution to the occurrence of high temperatures on interannual timescale. High temperatures associated with El Niño events mainly occurred during the winter annual period. As the Pacific Decadal Oscillation (PDO) struggled back to its positive phase since 2014, the global warming returned back to a new accelerated warming period, marked by the record-breaking high temperatures in 2014. Intensified by the super strong El Niño, successive high records occurred in 2015 and 2016. Higher frequencies of record high temperatures would occur in the near future because the PDO tends to maintain a continuously positive phase. PMID:28256561

Review on fatigue behavior of high-strength concrete after high temperature

NASA Astrophysics Data System (ADS)

Zhao, Dongfu; Jia, Penghe; Gao, Haijing

2017-06-01

The fatigue of high-strength concrete after high temperature has begun to attract attention. But so far the researches work about the fatigue of high-strength concrete after high temperature have not been reported. This article based on a large number of literature. The research work about the fatigue of high-strength concrete after high temperature are reviewed, analysed and expected, which can provide some reference for the experimental study of fatigue damage analysis.

Dynamic, High-Temperature, Flexible Seal

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Sirocky, Paul J.

1989-01-01

New seal consists of multiple plies of braided ceramic sleeves filled with small ceramic balls. Innermost braided sleeve supported by high-temperature-wire-mesh sleeve that provides both springback and preload capabilities. Ceramic balls reduce effect of relatively high porosity of braided ceramic sleeves by acting as labyrinth flow path for gases and thereby greatly increasing pressure gradient seal can sustain. Dynamic, high-temperature, flexible seal employed in hypersonic engines, two-dimensional convergent/divergent and vectorized-thrust exhaust nozzles, reentry vehicle airframes, rocket-motor casings, high-temperature furnaces, and any application requiring non-asbestos high-temperature gaskets.

Alumina ceramic based high-temperature performance of wireless passive pressure sensor

NASA Astrophysics Data System (ADS)

Wang, Bo; Wu, Guozhu; Guo, Tao; Tan, Qiulin

2016-12-01

A wireless passive pressure sensor equivalent to inductive-capacitive (LC) resonance circuit and based on alumina ceramic is fabricated by using high temperature sintering ceramic and post-fire metallization processes. Cylindrical copper spiral reader antenna and insulation layer are designed to realize the wireless measurement for the sensor in high temperature environment. The high temperature performance of the sensor is analyzed and discussed by studying the phase-frequency and amplitude-frequency characteristics of reader antenna. The average frequency change of sensor is 0.68 kHz/°C when the temperature changes from 27°C to 700°C and the relative change of twice measurements is 2.12%, with high characteristic of repeatability. The study of temperature-drift characteristic of pressure sensor in high temperature environment lays a good basis for the temperature compensation methods and insures the pressure signal readout accurately.

[Response and adaptation of photosynthesis of cucumber seedlings to high temperature stress].

PubMed

Sun, Sheng Nan; Wang, Qiang; Sun, Chen Chen; Liu, Feng Jiao; Bi, Huan Gai; Ai, Xi Zhen

2017-05-18

Cucumber seedlings (Cucumis sativus Jinyou 35) were used to study the effects of high temperature (HT: 42 ℃/32 ℃) and sub-high temperature (SHT: 35 ℃/25 ℃) on its photosynthesis and growth. The results showed that the growth of cucumber seedlings was dramatically inhibited by the high and sub-high temperature stresses. The photosynthetic rate (P n ) was gradually reduced, while intercellular CO 2 concentration (C i ) was increased as heat stress lasted. Under heat stress, stomatal conductance (g s ), transpiration rate (T r ), photorespiration rate (P r ) and dark respiration rate (D r ) showed a trend from rise to decline in cucumber seedlings, which implied that heat-induced decline of photosynthesis was mainly due to non-stomatal limitation. Maximal photochemical efficiency of PS2 in darkness (F v /F m ), actual photochemical efficiency (χ PS 2 ), photochemical quenching (q P ) and electron transport rate (ETR) were severely hampered, while initial fluorescence (F o ) and non-chemical quenching (NPQ) were increased as a result of high and sub-high temperature stresses. Under extended high temperature stress, the activities of RuBP carboxylase (RuBPCase) and Rubisco activase (RCA) as well as the mRNA abundance of Rubisco and RCA were in the trend of decrease, while they were reduced 3 days following the sub-high temperature treatment. The activities and mRNA expressions of sedoheptulose-1,7-bisphosphatase (SBPase) and fructose 1,6-bisphosphate aldolase (FBA) increased initially, but decreased afterwards under heat stress. Taken together, our data suggested that short-term sub-high temperature did not cause photoinhibition under optimal light conditions, however, high temperature led to severe damage to PS2 reaction center in cucumber seedlings. The photosynthetic enzymes were induced by high temperature stress and the induction was affected by temperature and stress duration.

High Speed, High Temperature, Fault Tolerant Operation of a Combination Magnetic-Hydrostatic Bearing Rotor Support System for Turbomachinery

NASA Technical Reports Server (NTRS)

Jansen, Mark; Montague, Gerald; Provenza, Andrew; Palazzolo, Alan

2004-01-01

Closed loop operation of a single, high temperature magnetic radial bearing to 30,000 RPM (2.25 million DN) and 540 C (1000 F) is discussed. Also, high temperature, fault tolerant operation for the three axis system is examined. A novel, hydrostatic backup bearing system was employed to attain high speed, high temperature, lubrication free support of the entire rotor system. The hydrostatic bearings were made of a high lubricity material and acted as journal-type backup bearings. New, high temperature displacement sensors were successfully employed to monitor shaft position throughout the entire temperature range and are described in this paper. Control of the system was accomplished through a stand alone, high speed computer controller and it was used to run both the fault-tolerant PID and active vibration control algorithms.

Nonlinear Constitutive Relations for High Temperature Application, 1984

NASA Technical Reports Server (NTRS)

1985-01-01

Nonlinear constitutive relations for high temperature applications were discussed. The state of the art in nonlinear constitutive modeling of high temperature materials was reviewed and the need for future research and development efforts in this area was identified. Considerable research efforts are urgently needed in the development of nonlinear constitutive relations for high temperature applications prompted by recent advances in high temperature materials technology and new demands on material and component performance. Topics discussed include: constitutive modeling, numerical methods, material testing, and structural applications.

A High Temperature Silicon Carbide mosfet Power Module With Integrated Silicon-On-Insulator-Based Gate Drive

DOE PAGES

Wang, Zhiqiang; Shi, Xiaojie; Tolbert, Leon M.; ...

2014-04-30

Here we present a board-level integrated silicon carbide (SiC) MOSFET power module for high temperature and high power density application. Specifically, a silicon-on-insulator (SOI)-based gate driver capable of operating at 200°C ambient temperature is designed and fabricated. The sourcing and sinking current capability of the gate driver are tested under various ambient temperatures. Also, a 1200 V/100 A SiC MOSFET phase-leg power module is developed utilizing high temperature packaging technologies. The static characteristics, switching performance, and short-circuit behavior of the fabricated power module are fully evaluated at different temperatures. Moreover, a buck converter prototype composed of the SOI gate drivermore » and SiC power module is built for high temperature continuous operation. The converter is operated at different switching frequencies up to 100 kHz, with its junction temperature monitored by a thermosensitive electrical parameter and compared with thermal simulation results. The experimental results from the continuous operation demonstrate the high temperature capability of the power module at a junction temperature greater than 225°C.« less

Effect of In-Situ Cure on Measurement of Glass Transition Temperatures in High-Temperature Thermosetting Polymers (Briefing Charts)

DTIC Science & Technology

2015-05-20

TEMPERATURES IN HIGH-TEMPERATURE THERMOSETTING POLYMERS 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...temperature thermosetting polymer via dynamic mechanical analysis alone. These difficulties result from the residual cure of samples heated beyond their...98) Prescribed by ANSI Std. 239.18 Effect of In-Situ Cure on Measurement of Glass Transition Temperatures in High-Temperature Thermosetting

A measurement system of high-temperature oxidation environment with ultrasonic Ir0.6Rth0.4 alloy thermometry.

PubMed

Wei, Yanlong; Wang, Gao; Gao, Yubin; Liu, Zhengguang; Xu, Lin; Tian, Miao; Yuan, Dongfang; Ren, Haiping; Zhou, Hanchang; Yang, Lu; Shi, Xueshun; Xiao, Zhaoqian

2018-04-03

Iridium-rhodium is generally applied as a thermocouple material, with max operating temperature about 2150 °C. In this study, a ultrasonic temperature measurement system was designed by using Iridium-rhodium (60%Ir-40%Rh) alloy as an acoustic waveguide sensor material, and the system was preliminarily tested in a high-temperature oxidation environment. The result of ultrasonic temperature measurement shows that this system can indeed work stably in high-temperature oxidation environments. The relationship between temperature and delay time of ultrasonic thermometry up to 2200 °C was illustrated. Iridium-rhodium materials were also investigated in order to fully elucidate the proposed waveguide sensor's performance in a high-temperature oxidation environment. This system lays a foundation for further application of high-temperature measurement. Copyright © 2018. Published by Elsevier B.V.

Deep Trek High Temperature Electronics Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruce Ohme

2007-07-31

This report summarizes technical progress achieved during the cooperative research agreement between Honeywell and U.S. Department of Energy to develop high-temperature electronics. Objects of this development included Silicon-on-Insulator (SOI) wafer process development for high temperature, supporting design tools and libraries, and high temperature integrated circuit component development including FPGA, EEPROM, high-resolution A-to-D converter, and a precision amplifier.

Acousto-optic Imaging System for In-situ Measurement of the High Temperature Distribution in Micron-size Specimens

NASA Astrophysics Data System (ADS)

Machikhin, Alexander S.; Zinin, Pavel V.; Shurygin, Alexander V.

We developed a unique acousto-optic imaging system for in-situ measurement of high temperature distribution on micron-size specimens. The system was designed to measure temperature distribution inside minerals and functional material phases subjected to high pressure and high temperatures in a diamond anvil cell (DAC) heated by a high powered laser.

Shear wave EMAT thickness measurements of low carbon steel at 450 °C without cooling

NASA Astrophysics Data System (ADS)

Lunn, Natasha; Potter, Mark; Dixon, Steve

2017-02-01

Performing high temperature online inspection without plant shutdown is highly desirable, yet, development of portable or permanently installed high temperature ultrasonic sensors, without the need for sample surface preparation, remains a key challenge. Low carbon steel pipelines operating at elevated temperatures often develop a magnetostrictive oxide coating (magnetite), which improves electromagnetic acoustic transducer (EMAT) efficiency below the Curie temperature of magnetite (575 °C), via a magnetostrictive mechanism. Coupling the inherent non-contacting nature of EMATs with the enhanced efficiency from a magnetite coating, we are able to continuously operate an uncoded EMAT at elevated temperatures without permanent installation or surface preparation. In this work, a high temperature shear wave EMAT utilizing a high field, high Curie point, permanent magnet has been developed to generate ultrasonic bulk thickness measurements on magnetite coated steel at temperatures of up to 450 °C, without cooling. Relatively high signal-to-noise ratios, in the region of 30 dB for single shot data, have been measured at 450 °C using this technique. The EMAT design and results from high temperature trials, including the performance with change in temperature, sample thickness and EMAT-sample lift-off, are presented here.

Measurement of high-dynamic temperature field using high-speed quadriwave lateral shearing interferometer

NASA Astrophysics Data System (ADS)

Cui, Bo-chuan; Wang, Jian-li; Yao, Kai-nan; Chen, Tao

2018-03-01

An approach to measure a high-dynamic two-dimensional (2D) temperature field using a high-speed quadriwave lateral shearing interferometer (QWLSI) is proposed. The detailed theoretical derivation to express the wavefront reconstruct principle of the proposed method is presented. The comparison experiment with thermocouples shows that the temperature field measurement using QWLSI has a precision of ±0.5 °C. An experiment for measuring the highdynamic temperature field generated by an electrical heater is carried out. A 200 frame rate temperature field video with 512 × 512 resolution is obtained finally. Experimental results show that the temperature field measurement system using a QWLSI has the advantage of high sensitivity and high resolution.

Impact of high temperature stress on floret fertility and individual grain weight of grain sorghum: sensitive stages and thresholds for temperature and duration

PubMed Central

Prasad, P. V. V.; Djanaguiraman, Maduraimuthu; Perumal, Ramasamy; Ciampitti, Ignacio A.

2015-01-01

Sorghum [Sorghum bicolor (L.) Moench] yield formation is severely affected by high temperature stress during reproductive stages. This study pursues to (i) identify the growth stage(s) most sensitive to high temperature stress during reproductive development, (ii) determine threshold temperature and duration of high temperature stress that decreases floret fertility and individual grain weight, and (iii) quantify impact of high daytime temperature during floret development, flowering and grain filling on reproductive traits and grain yield under field conditions. Periods between 10 and 5 d before anthesis; and between 5 d before- and 5 d after-anthesis were most sensitive to high temperatures causing maximum decreases in floret fertility. Mean daily temperatures >25°C quadratically decreased floret fertility (reaching 0% at 37°C) when imposed at the start of panicle emergence. Temperatures ranging from 25 to 37°C quadratically decreased individual grain weight when imposed at the start of grain filling. Both floret fertility and individual grain weights decreased quadratically with increasing duration (0–35 d or 49 d during floret development or grain filling stage, respectively) of high temperature stress. In field conditions, imposition of temperature stress (using heat tents) during floret development or grain filling stage also decreased floret fertility, individual grain weight, and grain weight per panicle. PMID:26500664

Comparison of the temperature accuracy between smart phone based and high-end thermal cameras using a temperature gradient phantom

NASA Astrophysics Data System (ADS)

Klaessens, John H.; van der Veen, Albert; Verdaasdonk, Rudolf M.

2017-03-01

Recently, low cost smart phone based thermal cameras are being considered to be used in a clinical setting for monitoring physiological temperature responses such as: body temperature change, local inflammations, perfusion changes or (burn) wound healing. These thermal cameras contain uncooled micro-bolometers with an internal calibration check and have a temperature resolution of 0.1 degree. For clinical applications a fast quality measurement before use is required (absolute temperature check) and quality control (stability, repeatability, absolute temperature, absolute temperature differences) should be performed regularly. Therefore, a calibrated temperature phantom has been developed based on thermistor heating on both ends of a black coated metal strip to create a controllable temperature gradient from room temperature 26 °C up to 100 °C. The absolute temperatures on the strip are determined with software controlled 5 PT-1000 sensors using lookup tables. In this study 3 FLIR-ONE cameras and one high end camera were checked with this temperature phantom. The results show a relative good agreement between both low-cost and high-end camera's and the phantom temperature gradient, with temperature differences of 1 degree up to 6 degrees between the camera's and the phantom. The measurements were repeated as to absolute temperature and temperature stability over the sensor area. Both low-cost and high-end thermal cameras measured relative temperature changes with high accuracy and absolute temperatures with constant deviations. Low-cost smart phone based thermal cameras can be a good alternative to high-end thermal cameras for routine clinical measurements, appropriate to the research question, providing regular calibration checks for quality control.

Method of manufacturing a high temperature superconductor with improved transport properties

DOEpatents

Balachandran, Uthamalingam; Siegel, Richard W.; Askew, Thomas R.

2001-01-01

A method of preparing a high temperature superconductor. A method of preparing a superconductor includes providing a powdered high temperature superconductor and a nanophase paramagnetic material. These components are combined to form a solid compacted mass with the paramagnetic material disposed on the grain boundaries of the polycrystaline high temperature superconductor.

[Study of high temperature water vapor concentration measurement method based on absorption spectroscopy].

PubMed

Chen, Jiu-ying; Liu, Jian-guo; He, Jun-feng; He, Ya-bai; Zhang, Guang-le; Xu, Zhen-yu; Gang, Qiang; Wang, Liao; Yao, Lu; Yuan, Song; Ruan, Jun; Dai, Yun-hai; Kan, Rui-feng

2014-12-01

Tunable diode laser absorption spectroscopy (TDLAS) has been developed to realize the real-time and dynamic measurement of the combustion temperature, gas component concentration, velocity and other flow parameters, owing to its high sensitivity, fast time response, non-invasive character and robust nature. In order to obtain accurate water vapor concentration at high temperature, several absorption spectra of water vapor near 1.39 μm from 773 to 1273 K under ordinary pressure were recorded in a high temperature experiment setup using a narrow band diode laser. The absorbance of high temperature absorption spectra was calculated by combined multi-line nonlinear least squares fitting method. Two water vapor absorption lines near 7154.35 and 7157.73 cm(-1) were selected for measurement of water vapor at high temperature. A model method for high temperature water vapor concentration was first proposed. Water vapor concentration from the model method at high temperature is in accordance with theoretical reasoning, concentration measurement standard error is less than 0.2%, and the relative error is less than 6%. The feasibility of this measuring method is verified by experiment.

Development of Metal Oxide Nanostructure-based Optical Sensors for Fossil Fuel Derived Gases Measurement at High Temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Kevin P.

2015-02-13

This final technical report details research works performed supported by a Department of Energy grant (DE-FE0003859), which was awarded under the University Coal Research Program administrated by National Energy Technology Laboratory. This research program studied high temperature fiber sensor for harsh environment applications. It developed two fiber optical sensor platform technology including regenerative fiber Bragg grating sensors and distributed fiber optical sensing based on Rayleigh backscattering optical frequency domain reflectometry. Through the studies of chemical and thermal regenerative techniques for fiber Bragg grating (FBG) fabrication, high-temperature stable FBG sensors were successfully developed and fabricated in air-hole microstructured fibers, high-attenuation fibers,more » rare-earth doped fibers, and standard telecommunication fibers. By optimizing the laser processing and thermal annealing procedures, fiber grating sensors with stable performance up to 1100°C have been developed. Using these temperature-stable FBG gratings as sensor platform, fiber optical flow, temperature, pressure, and chemical sensors have been developed to operate at high temperatures up to 800°C. Through the integration of on-fiber functional coating, the use of application-specific air-hole microstructural fiber, and application of active fiber sensing scheme, distributed fiber sensor for temperature, pressure, flow, liquid level, and chemical sensing have been demonstrated with high spatial resolution (1-cm or better) with wide temperature ranges. These include the demonstration of 1) liquid level sensing from 77K to the room temperature, pressure/temperature sensing from the room temperature to 800C and from the 15psi to 2000 psi, and hydrogen concentration measurement from 0.2% to 10% with temperature ranges from the room temperature to 700°C. Optical sensors developed by this program has broken several technical records including flow sensors with the highest operation temperature up to 750°C, first distributed chemical measurements at the record high temperature up to 700°C, first distributed pressure measurement at the record high temperature up to 800°C, and the fiber laser sensors with the record high operation temperature up to 700°C. The research performed by this program dramatically expand the functionality, adaptability, and applicability of distributed fiber optical sensors with potential applications in a number of high-temperature energy systems such as fossil-fuel power generation, high-temperature fuel cell applications, and potential for nuclear energy systems.« less

Application of TL dosemeters for dose distribution measurements at high temperatures in nuclear reactors.

PubMed

Osvay, M; Deme, S

2006-01-01

Al2O3:Mg,Y ceramic thermoluminescence dosemeters were developed at the Institute of Isotopes for high dose applications at room temperatures. The glow curve of Al2O3:Mg,Y exhibits two peaks--one at 250 degrees C (I) and another peak at approximately 400 degrees C (II). In order to extend the application of these dosemeters to high temperatures, the effect of irradiation temperature was investigated using temperature controlled heating system during high dose irradiation at various temperatures (20-100 degrees C). The new calibration and measuring method has been successfully applied for dose mapping within the hermetic zone of the Paks Nuclear Power Plant even at high temperature parts of blocks.

High- and low-temperature-stable thermite composition for producing high-pressure, high-velocity gases

DOEpatents

Halcomb, Danny L.; Mohler, Jonathan H.

1990-10-16

A high- and low-temperature-stable thermite composition for producing high-pressure and high-velocity gases comprises an oxidizable metal, an oxidizing reagent, and a high-temperature-stable gas-producing additive selected from the group consisting of metal carbides and metal nitrides.

High refractive index and temperature sensitivity LPGs for high temperature operation

NASA Astrophysics Data System (ADS)

Nascimento, I. M.; Gouveia, C.; Jana, Surnimal; Bera, Susanta; Baptista, J. M.; Moreira, Paulo; Biwas, Palas; Bandyopadhyay, Somnath; Jorge, Pedro A. S.

2013-11-01

A fiber optic sensor for high sensitivity refractive index and temperature measurement able to withstand temperature up to 450 °C is reported. Two identical LPG gratings were fabricated, whereas one was coated with a high refractive index (~1.78) sol-gel thin film in order to increase its sensitivity to the external refractive index. The two sensors were characterized and compared in refractive index and temperature. Sensitivities of 1063 nm/RIU (1.338 - 1.348) and 260 pm/°C were achieved for refractive index and temperature, respectively.

Temperature compensated high-temperature/high-pressure Merrill--Bassett diamond anvil cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schiferl, D.

1987-07-01

A Merrill--Bassett diamond anvil cell for high-temperature/high-pressure studies up to 5 GPa at 1000 K and 13 GPa at 725 K is described. To maintain uniform, well-characterized temperatures, and to protect the diamond anvils from oxidation and graphitization, the entire cell is heated in a vacuum oven. The materials are chosen so that the pressure remains constant to within +-10% over the entire temperature range.

Germanium resistance thermometer calibration at superfluid helium temperatures

NASA Technical Reports Server (NTRS)

Mason, F. C.

1985-01-01

The rapid increase in resistance of high purity semi-conducting germanium with decreasing temperature in the superfluid helium range of temperatures makes this material highly adaptable as a very sensitive thermometer. Also, a germanium thermometer exhibits a highly reproducible resistance versus temperature characteristic curve upon cycling between liquid helium temperatures and room temperature. These two factors combine to make germanium thermometers ideally suited for measuring temperatures in many cryogenic studies at superfluid helium temperatures. One disadvantage, however, is the relatively high cost of calibrated germanium thermometers. In space helium cryogenic systems, many such thermometers are often required, leading to a high cost for calibrated thermometers. The construction of a thermometer calibration cryostat and probe which will allow for calibrating six germanium thermometers at one time, thus effecting substantial savings in the purchase of thermometers is considered.

Silicon Carbide-Based Hydrogen Gas Sensors for High-Temperature Applications

PubMed Central

Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

2013-01-01

We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures. PMID:24113685

Silicon carbide-based hydrogen gas sensors for high-temperature applications.

PubMed

Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

2013-10-09

We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

Thermodynamics and Transport Phenomena in High Temperature Steam Electrolysis Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

James E. O'Brien

2012-03-01

Hydrogen can be produced from water splitting with relatively high efficiency using high temperature electrolysis. This technology makes use of solid-oxide cells, running in the electrolysis mode to produce hydrogen from steam, while consuming electricity and high temperature process heat. The overall thermal-to-hydrogen efficiency for high temperature electrolysis can be as high as 50%, which is about double the overall efficiency of conventional low-temperature electrolysis. Current large-scale hydrogen production is based almost exclusively on steam reforming of methane, a method that consumes a precious fossil fuel while emitting carbon dioxide to the atmosphere. An overview of high temperature electrolysis technologymore » will be presented, including basic thermodynamics, experimental methods, heat and mass transfer phenomena, and computational fluid dynamics modeling.« less

Des-acyl ghrelin prevents heatstroke-like symptoms in rats exposed to high temperature and high humidity.

PubMed

Inoue, Yoshiyuki; Hayashi, Yujiro; Kangawa, Kenji; Suzuki, Yoshihiro; Murakami, Noboru; Nakahara, Keiko

2016-02-26

We have shown previously that des-acyl ghrelin decreases body temperature in rats through activation of the parasympathetic nervous system. Here we investigated whether des-acyl ghrelin ameliorates heatstroke in rats exposed to high temperature. Peripheral administration of des-acyl ghrelin significantly attenuated hyperthermia induced by exposure to high-temperature (35°C) together with high humidity (70-80%). Although biochemical analysis revealed that exposure to high temperature significantly increased hematocrit and the serum levels of aspartate amino transferase (AST), alanine transaminase (ALT), blood urea nitrogen (BUN), creatinine and electrolytes (Na(+), K(+), Cl(-)), most of these heatstroke-associated reactions were significantly reduced by treatment with des-acyl ghrelin. The level of des-acyl ghrelin in plasma was also found to be significantly increased under high-temperature conditions. These results suggest that des-acyl ghrelin could be useful for preventing heatstroke under high temperature condition. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Suppression of OsMADS7 in rice endosperm stabilizes amylose content under high temperature stress.

PubMed

Zhang, Hua; Xu, Heng; Feng, Mengjie; Zhu, Ying

2018-01-01

High temperature significantly alters the amylose content of rice, resulting in mature grains with poor eating quality. However, only few genes and/or quantitative trait loci involved in this process have been isolated and the molecular mechanisms of this effect remain unclear. Here, we describe a floral organ identity gene, OsMADS7, involved in stabilizing rice amylose content at high temperature. OsMADS7 is greatly induced by high temperature at the early filling stage. Constitutive suppression of OsMADS7 stabilizes amylose content under high temperature stress but results in low spikelet fertility. However, rice plants with both stable amylose content at high temperature and normal spikelet fertility can be obtained by specifically suppressing OsMADS7 in endosperm. GBSSI is the major enzyme responsible for amylose biosynthesis. A low filling rate and high expression of GBSSI were detected in OsMADS7 RNAi plants at high temperature, which may be correlated with stabilized amylose content in these transgenic seeds under high temperature. Thus, specific suppression of OsMADS7 in endosperm could improve the stability of rice amylose content at high temperature, and such transgenic materials may be a valuable genetic resource for breeding rice with elite thermal resilience. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Transcriptomic study to understand thermal adaptation in a high temperature-tolerant strain of Pyropia haitanensis

PubMed Central

Wang, Wenlei; Teng, Fei; Lin, Yinghui; Ji, Dehua; Xu, Yan; Chen, Changsheng

2018-01-01

Pyropia haitanensis, a high-yield commercial seaweed in China, is currently undergoing increasing levels of high-temperature stress due to gradual global warming. The mechanisms of plant responses to high temperature stress vary with not only plant type but also the degree and duration of high temperature. To understand the mechanism underlying thermal tolerance in P. haitanensis, gene expression and regulation in response to short- and long-term temperature stresses (SHS and LHS) was investigated by performing genome-wide high-throughput transcriptomic sequencing for a high temperature tolerant strain (HTT). A total of 14,164 differential expression genes were identified to be high temperature-responsive in at least one time point by high-temperature treatment, representing 41.10% of the total number of unigenes. The present data indicated a decrease in the photosynthetic and energy metabolic rates in HTT to reduce unnecessary energy consumption, which in turn facilitated in the rapid establishment of acclimatory homeostasis in its transcriptome during SHS. On the other hand, an increase in energy consumption and antioxidant substance activity was observed with LHS, which apparently facilitates in the development of resistance against severe oxidative stress. Meanwhile, ubiquitin-mediated proteolysis, brassinosteroids, and heat shock proteins also play a vital role in HTT. The effects of SHS and LHS on the mechanism of HTT to resist heat stress were relatively different. The findings may facilitate further studies on gene discovery and the molecular mechanisms underlying high-temperature tolerance in P. haitanensis, as well as allow improvement of breeding schemes for high temperature-tolerant macroalgae that can resist global warming. PMID:29694388

Transcriptomic study to understand thermal adaptation in a high temperature-tolerant strain of Pyropia haitanensis.

PubMed

Wang, Wenlei; Teng, Fei; Lin, Yinghui; Ji, Dehua; Xu, Yan; Chen, Changsheng; Xie, Chaotian

2018-01-01

Pyropia haitanensis, a high-yield commercial seaweed in China, is currently undergoing increasing levels of high-temperature stress due to gradual global warming. The mechanisms of plant responses to high temperature stress vary with not only plant type but also the degree and duration of high temperature. To understand the mechanism underlying thermal tolerance in P. haitanensis, gene expression and regulation in response to short- and long-term temperature stresses (SHS and LHS) was investigated by performing genome-wide high-throughput transcriptomic sequencing for a high temperature tolerant strain (HTT). A total of 14,164 differential expression genes were identified to be high temperature-responsive in at least one time point by high-temperature treatment, representing 41.10% of the total number of unigenes. The present data indicated a decrease in the photosynthetic and energy metabolic rates in HTT to reduce unnecessary energy consumption, which in turn facilitated in the rapid establishment of acclimatory homeostasis in its transcriptome during SHS. On the other hand, an increase in energy consumption and antioxidant substance activity was observed with LHS, which apparently facilitates in the development of resistance against severe oxidative stress. Meanwhile, ubiquitin-mediated proteolysis, brassinosteroids, and heat shock proteins also play a vital role in HTT. The effects of SHS and LHS on the mechanism of HTT to resist heat stress were relatively different. The findings may facilitate further studies on gene discovery and the molecular mechanisms underlying high-temperature tolerance in P. haitanensis, as well as allow improvement of breeding schemes for high temperature-tolerant macroalgae that can resist global warming.

The effects of gender on circadian rhythm of human physiological indexes in high temperature environment

NASA Astrophysics Data System (ADS)

Zheng, G. Z.; Li, K.; Bu, W. T.; Lu, Y. Z.; Wang, Y. J.

2018-03-01

In the context of frequent high temperature weather in recent years, peoples’ physical health is seriously threatened by the indoor high temperature. The physiological activities of human body show a certain changes of circadian rhythm. In this paper, the circadian rhythms of the physiological indexes in indoor high temperature environment were quantified and compared between the male subjects and female subjects. Ten subjects (five males and five females) were selected. The temperature conditions were set at 28°C, 32°C, 36°C and 38°C, respectively. The blood pressure, heart rate, rectal temperature, eardrum temperature, forehead temperature and mean skin temperature were measured for 24 hours continuously. The medians, amplitudes and acrophases of the circadian rhythms were obtained by the cosinor analysis method. Then the effects of gender on the circadian rhythm of the human body in high temperature environment were analyzed. The results indicate that, compared with the female subjects, the male medians of the systolic pressure and diastolic pressure were higher, and the male medians of heart rate and rectal temperature were lower, however, no significant differences were found between eardrum temperature, forehead temperature and mean skin temperature. This study can provide scientific basis for the health protection of the indoor relevant personnel.

High temperature deformation of NiAl and CoAl

NASA Technical Reports Server (NTRS)

Nix, W. D.

1982-01-01

The high temperature mechanical properties of the aluminides are reviewed with respect to their potential as high temperature structural materials. It is shown that NiAl and CoAl are substantially stronger than the pure metals Ni and Co at high temperatures and approach the strength of some superalloys, particularly when those superalloys are tested in "weak" directions. The factors that limit and control the high temperature strengths of NiAl and CoAl are examined to provide a basis for the development of intermetallic alloys of this type.

A high-temperature superconducting transformer with localized magnetic field

NASA Astrophysics Data System (ADS)

Volkov, E. P.; Dzhafarov, E. A.

2013-12-01

This paper describes a high-temperature superconducting transformer with a bar-type magnetic core and concentric windings with alternating layers, with single-channel and multi-channel arrangements. There is given the design concept of high-temperature superconducting windings of the transformer, made in the form of newly developed first-generation high-temperature superconducting ribbon wires, with localized magnetic field intended for producing maximum transport currents in the windings, as well as for reducing the consumption of a high-temperature superconducting material, cooling agent, and energy losses in these windings.

Copper Alloy For High-Temperature Uses

NASA Technical Reports Server (NTRS)

Dreshfield, Robert L.; Ellis, David L.; Michal, Gary

1994-01-01

Alloy of Cu/8Cr/4Nb (numbers indicate parts by atom percent) improved over older high-temperature copper-based alloys in that it offers enhanced high temperature strength, resistance to creep, and ductility while retaining most of thermal conductivity of pure copper; in addition, alloy does not become embrittled upon exposure to hydrogen at temperatures as high as 705 degrees C. Designed for use in presence of high heat fluxes and active cooling; for example, in heat exchangers in advanced aircraft and spacecraft engines, and other high-temperature applications in which there is need for such material. High conductivity and hardness of alloy exploited in welding electrodes and in high-voltage and high-current switches and other applications in which wear poses design problem.

High Temperature Ultrasonic Probe and Pulse-Echo Probe Mounting Fixture for Testing and Blind Alignment on Steam Pipes

NASA Technical Reports Server (NTRS)

Lih, Shyh-Shiuh (Inventor); Takano, Nobuyuki (Inventor); Lee, Hyeong Jae (Inventor); Bao, Xiaoqi (Inventor); Badescu, Mircea (Inventor); Bar-Cohen, Yoseph (Inventor); Sherrit, Stewart (Inventor); Ostlund, Patrick N. (Inventor)

2017-01-01

A high temperature ultrasonic probe and a mounting fixture for attaching and aligning the probe to a steam pipe using blind alignment. The high temperature ultrasonic probe includes a piezoelectric transducer having a high temperature. The probe provides both transmitting and receiving functionality. The mounting fixture allows the high temperature ultrasonic probe to be accurately aligned to the bottom external surface of the steam pipe so that the presence of liquid water in the steam pipe can be monitored. The mounting fixture with a mounted high temperature ultrasonic probe are used to conduct health monitoring of steam pipes and to track the height of condensed water through the wall in real-time.

High Ambient Temperature Represses Anthocyanin Biosynthesis through Degradation of HY5

PubMed Central

Kim, Sara; Hwang, Geonhee; Lee, Seulgi; Zhu, Jia-Ying; Paik, Inyup; Nguyen, Thom Thi; Kim, Jungmook; Oh, Eunkyoo

2017-01-01

Anthocyanins are flavonoid compounds that protect plant tissues from many environmental stresses including high light irradiance, freezing temperatures, and pathogen infection. Regulation of anthocyanin biosynthesis is intimately associated with environmental changes to enhance plant survival under stressful environmental conditions. Various factors, such as UV, visible light, cold, osmotic stress, and pathogen infection, can induce anthocyanin biosynthesis. In contrast, high temperatures are known to reduce anthocyanin accumulation in many plant species, even drastically in the skin of fruits such as grape berries and apples. However, the mechanisms by which high temperatures regulate anthocyanin biosynthesis in Arabidopsis thaliana remain largely unknown. Here, we show that high ambient temperatures repress anthocyanin biosynthesis through the E3 ubiquitin ligase CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) and the positive regulator of anthocyanin biosynthesis ELONGATED HYPOCOTYL5 (HY5). We show that an increase in ambient temperature decreases expression of genes required in both the early and late steps of the anthocyanin biosynthesis pathway in Arabidopsis seedlings. As a result, seedlings grown at a high temperature (28°C) accumulate less anthocyanin pigment than those grown at a low temperature (17°C). We further show that high temperature induces the degradation of the HY5 protein in a COP1 activity-dependent manner. In agreement with this finding, anthocyanin biosynthesis and accumulation do not respond to ambient temperature changes in cop1 and hy5 mutant plants. The degradation of HY5 derepresses the expression of MYBL2, which partially mediates the high temperature repression of anthocyanin biosynthesis. Overall, our study demonstrates that high ambient temperatures repress anthocyanin biosynthesis through a COP1-HY5 signaling module. PMID:29104579

Ultra-High Temperature Materials Characterization for Space and Missile Applications

NASA Technical Reports Server (NTRS)

Rogers, Jan; Hyers, Robert

2007-01-01

Numerous advanced space and missile technologies including propulsion systems require operations at high temperatures. Some very high-temperature materials are being developed to meet these needs, including refractory metal alloys, carbides, borides, and silicides. System design requires data for materials properties at operating temperatures. Materials property data are not available at the desired operating temperatures for many materials of interest. The objective of this work is to provide important physical property data at ultra-high temperatures. The MSFC Electrostatic Levitation (ESL) facility can provide measurements of thermophysical properties which include: creep strength, emissivity, density and thermal expansion. ESL uses electrostatic fields to position samples between electrodes during processing and characterization experiments. Samples float between the electrodes during studies and are free from any contact with a container or test apparatus. This provides a high purity environment for the study of high-temperature, reactive materials. ESL can be used to process a wide variety of materials including metals, alloys, ceramics, glasses and semiconductors. A system for the determination of total hemispherical emissivity is being developed for the MSFC ESL facility by AZ Technology Inc. The instrument has been designed to provide emissivity measurements for samples during ESL experiments over the temperature range 700-3400K. A novel non-contact technique for the determination of high-temperature creep strength has been developed. Data from selected ESL-based characterization studies will be presented. The ESL technique could advance space and missile technologies by advancing the knowledge base and the technology readiness level for ultra-high temperature materials. Applications include non-eroding nozzle materials and lightweight, high-temperature alloys for turbines and structures.

Friction Durability of Extremely Thin Diamond-Like Carbon Films at High Temperature

PubMed Central

Miyake, Shojiro; Suzuki, Shota; Miyake, Masatoshi

2017-01-01

To clarify the friction durability, both during and after the high-temperature heating of nanometer-thick diamond-like carbon (DLC) films, deposited using filtered cathodic vacuum arc (FCVA) and plasma chemical vapor deposition (P-CVD) methods, the dependence of the friction coefficient on the load and sliding cycles of the DLC films, were evaluated. Cluster-I consisted of a low friction area in which the DLC film was effective, while cluster-II consisted of a high friction area in which the lubricating effect of the DLC film was lost. The friction durability of the films was evaluated by statistical cluster analysis. Extremely thin FCVA-DLC films exhibited an excellent wear resistance at room temperature, but their friction durability was decreased at high temperatures. In contrast, the durability of the P-CVD-DLC films was increased at high temperatures when compared with that observed at room temperature. This inverse dependence on temperature corresponded to the nano-friction results obtained by atomic force microscopy. The decrease in the friction durability of the FCVA-DLC films at high temperatures, was caused by a complex effect of temperature and friction. The tribochemical reaction produced by the P-CVD-DLC films reduced their friction coefficient, increasing their durability at high temperatures. PMID:28772520

Friction Durability of Extremely Thin Diamond-Like Carbon Films at High Temperature.

PubMed

Miyake, Shojiro; Suzuki, Shota; Miyake, Masatoshi

2017-02-10

To clarify the friction durability, both during and after the high-temperature heating of nanometer-thick diamond-like carbon (DLC) films, deposited using filtered cathodic vacuum arc (FCVA) and plasma chemical vapor deposition (P-CVD) methods, the dependence of the friction coefficient on the load and sliding cycles of the DLC films, were evaluated. Cluster-I consisted of a low friction area in which the DLC film was effective, while cluster-II consisted of a high friction area in which the lubricating effect of the DLC film was lost. The friction durability of the films was evaluated by statistical cluster analysis. Extremely thin FCVA-DLC films exhibited an excellent wear resistance at room temperature, but their friction durability was decreased at high temperatures. In contrast, the durability of the P-CVD-DLC films was increased at high temperatures when compared with that observed at room temperature. This inverse dependence on temperature corresponded to the nano-friction results obtained by atomic force microscopy. The decrease in the friction durability of the FCVA-DLC films at high temperatures, was caused by a complex effect of temperature and friction. The tribochemical reaction produced by the P-CVD-DLC films reduced their friction coefficient, increasing their durability at high temperatures.

Data center thermal management

DOEpatents

Hamann, Hendrik F.; Li, Hongfei

2016-02-09

Historical high-spatial-resolution temperature data and dynamic temperature sensor measurement data may be used to predict temperature. A first formulation may be derived based on the historical high-spatial-resolution temperature data for determining a temperature at any point in 3-dimensional space. The dynamic temperature sensor measurement data may be calibrated based on the historical high-spatial-resolution temperature data at a corresponding historical time. Sensor temperature data at a plurality of sensor locations may be predicted for a future time based on the calibrated dynamic temperature sensor measurement data. A three-dimensional temperature spatial distribution associated with the future time may be generated based on the forecasted sensor temperature data and the first formulation. The three-dimensional temperature spatial distribution associated with the future time may be projected to a two-dimensional temperature distribution, and temperature in the future time for a selected space location may be forecasted dynamically based on said two-dimensional temperature distribution.

The stress relaxation of cement clinkers under high temperature

NASA Astrophysics Data System (ADS)

Wang, Xiufang; Bao, Yiwang; Liu, Xiaogen; Qiu, Yan

2015-12-01

The energy consumption of crushing is directly affected by the mechanical properties of cement materials. This research provides a theoretical proof for the mechanism of the stress relaxation of cement clinkers under high temperature. Compression stress relaxation under various high temperatures is discussed using a specially developed load cell, which can measure stress and displacement under high temperatures inside an autoclave. The cell shows that stress relaxation dramatically increases and that the remaining stress rapidly decreases with an increase in temperature. Mechanical experiments are conducted under various temperatures during the cooling process to study the changes in the grinding resistance of the cement clinker with temperature. The effects of high temperature on the load-displacement curve, compressive strength, and elastic modulus of cement clinkers are systematically studied. Results show that the hardening phenomenon of the clinker becomes apparent with a decrease in temperature and that post-peak behaviors manifest characteristics of the transformation from plasticity to brittleness. The elastic modulus and compressive strength of cement clinkers increase with a decrease in temperature. The elastic modulus increases greatly when the temperature is lower than 1000 °C. The compressive strength of clinkers increases by 73.4% when the temperature drops from 1100 to 800 °C.

The Effect of Acclimation to Sublethal Temperature on Subsequent Susceptibility of Sitophilus zeamais Mostchulsky (Coleoptera: Curculionidae) to High Temperatures

PubMed Central

Lü, Jianhua; Zhang, Huina

2016-01-01

Heat treatment is a popular alternative to synthetic pesticides in disinfesting food-processing facilities and empty grain storages. Sitophilus zeamais Mostchulsky is one of the most cosmopolitan and destructive insects found in empty grain storage facilities and processing facilities. The effect of acclimation in S. zeamais adults to sublethal high temperature on their subsequent susceptibility to high temperatures was investigated. S. zeamais adults were acclimated to 36°C for 0 (as a control), 1, 3, and 5 h, and then were exposed at 43, 47, 51, and 55°C for different time intervals respectively. Acclimation to sublethal high temperature significantly reduced subsequent susceptibility of S. zeamais adults to lethal high temperatures of 43, 47, 51, and 55°C, although the mortality of S. zeamais adults significantly increased with increasing exposure time at lethal high temperatures. The mortality of S. zeamais adults with 1, 3, and 5 h of acclimation to 36°C was significantly lower than that of S. zeamais adults without acclimation when exposed to the same lethal high temperatures. The present results suggest that the whole facility should be heated to target lethal high temperature as soon as possible, avoiding decreasing the control effectiveness of heat treatment due to the acclimation in stored product insects to sublethal temperature. PMID:27462906

Boron application improves yield of rice cultivars under high temperature stress during vegetative and reproductive stages.

PubMed

Shahid, Mohammad; Nayak, Amaresh Kumar; Tripathi, Rahul; Katara, Jawahar Lal; Bihari, Priyanka; Lal, Banwari; Gautam, Priyanka

2018-04-12

It is reported that high temperatures (HT) would cause a marked decrease in world rice production. In tropical regions, high temperatures are a constraint to rice production and the most damaging effect is on spikelet sterility. Boron (B) plays a very important role in the cell wall formation, sugar translocation, and reproduction of the rice crop and could play an important role in alleviating high temperature stress. A pot culture experiment was conducted to study the effect of B application on high temperature tolerance of rice cultivars in B-deficient soil. The treatments comprised of four boron application treatments viz. control (B0), soil application of 1 kg B ha -1 (B1), soil application of 2 kg B ha -1 (B2), and foliar spray of 0.2% B (Bfs); three rice cultivars viz. Annapurna (HT stress tolerant), Naveen, and Shatabdi (both HT stress susceptible); and three temperature regimes viz. ambient (AT), HT at vegetative stage (HTV), and HT at reproductive stage (HTR). The results revealed that high temperature stress during vegetative or flowering stage reduced grain yield of rice cultivars mainly because of low pollen viability and spikelet fertility. The effects of high temperature on the spikelet fertility and grain filling varied among cultivars and the growth stages of plant when exposed to the high temperature stress. Under high temperature stress, the tolerant cultivar displays higher cell membrane stability, less accumulation of osmolytes, more antioxidant enzyme activities, and higher pollen viability and spikelet fertility than the susceptible cultivars. In the present work, soil application of boron was effective in reducing the negative effects of high temperature both at vegetative and reproductive stages. Application of B results into higher grain yield under both ambient and high temperature condition over control for all the three cultivars; however, more increase was observed for the susceptible cultivar over the tolerant one. The results suggest that the exogenous application of boron had a substantial effect on cell membrane stability, sugar mobilization, pollen viability, and spikelet fertility, hence the yield. The cultivars due to their variation in the tolerance level for high temperature stress behaved differently, and at high temperature stress, more response of the application of boron was seen in susceptible cultivars.

Boron application improves yield of rice cultivars under high temperature stress during vegetative and reproductive stages

NASA Astrophysics Data System (ADS)

Shahid, Mohammad; Nayak, Amaresh Kumar; Tripathi, Rahul; Katara, Jawahar Lal; Bihari, Priyanka; Lal, Banwari; Gautam, Priyanka

2018-04-01

It is reported that high temperatures (HT) would cause a marked decrease in world rice production. In tropical regions, high temperatures are a constraint to rice production and the most damaging effect is on spikelet sterility. Boron (B) plays a very important role in the cell wall formation, sugar translocation, and reproduction of the rice crop and could play an important role in alleviating high temperature stress. A pot culture experiment was conducted to study the effect of B application on high temperature tolerance of rice cultivars in B-deficient soil. The treatments comprised of four boron application treatments viz. control (B0), soil application of 1 kg B ha-1 (B1), soil application of 2 kg B ha-1 (B2), and foliar spray of 0.2% B (Bfs); three rice cultivars viz. Annapurna (HT stress tolerant), Naveen, and Shatabdi (both HT stress susceptible); and three temperature regimes viz. ambient (AT), HT at vegetative stage (HTV), and HT at reproductive stage (HTR). The results revealed that high temperature stress during vegetative or flowering stage reduced grain yield of rice cultivars mainly because of low pollen viability and spikelet fertility. The effects of high temperature on the spikelet fertility and grain filling varied among cultivars and the growth stages of plant when exposed to the high temperature stress. Under high temperature stress, the tolerant cultivar displays higher cell membrane stability, less accumulation of osmolytes, more antioxidant enzyme activities, and higher pollen viability and spikelet fertility than the susceptible cultivars. In the present work, soil application of boron was effective in reducing the negative effects of high temperature both at vegetative and reproductive stages. Application of B results into higher grain yield under both ambient and high temperature condition over control for all the three cultivars; however, more increase was observed for the susceptible cultivar over the tolerant one. The results suggest that the exogenous application of boron had a substantial effect on cell membrane stability, sugar mobilization, pollen viability, and spikelet fertility, hence the yield. The cultivars due to their variation in the tolerance level for high temperature stress behaved differently, and at high temperature stress, more response of the application of boron was seen in susceptible cultivars.

High Work Output Ni-Ti-Pt High Temperature Shape Memory Alloys and Associated Processing Methods

NASA Technical Reports Server (NTRS)

Noebe, Ronald D. (Inventor); Draper, Susan L. (Inventor); Nathal, Michael V. (Inventor); Garg, Anita (Inventor)

2009-01-01

According to the invention, compositions of Ni-Ti-Pt high temperature, high force, shape memory alloys are disclosed that have transition temperatures above 100 C.; have narrow hysteresis; and produce a high specific work output.

Mechanical and Microstructure Study of Nickel-Based ODS Alloys Processed by Mechano-Chemical Bonding and Ball Milling

NASA Astrophysics Data System (ADS)

Amare, Belachew N.

Due to the need to increase the efficiency of modern power plants, land-based gas turbines are designed to operate at high temperature creating harsh environments for structural materials. The elevated turbine inlet temperature directly affects the materials at the hottest sections, which includes combustion chamber, blades, and vanes. Therefore, the hottest sections should satisfy a number of material requirements such as high creep strength, ductility at low temperature, high temperature oxidation and corrosion resistance. Such requirements are nowadays satisfied by implementing superalloys coated by high temperature thermal barrier coating (TBC) systems to protect from high operating temperature required to obtain an increased efficiency. Oxide dispersive strengthened (ODS) alloys are being considered due to their high temperature creep strength, good oxidation and corrosion resistance for high temperature applications in advanced power plants. These alloys operating at high temperature are subjected to different loading systems such as thermal, mechanical, and thermo-mechanical combined loads at operation. Thus, it is critical to study the high temperature mechanical and microstructure properties of such alloys for their structural integrity. The primary objective of this research work is to investigate the mechanical and microstructure properties of nickel-based ODS alloys produced by combined mechano-chemical bonding (MCB) and ball milling subjected to high temperature oxidation, which are expected to be applied for high temperature turbine coating with micro-channel cooling system. Stiffness response and microstructure evaluation of such alloy systems was studied along with their oxidation mechanism and structural integrity through thermal cyclic exposure. Another objective is to analyze the heat transfer of ODS alloy coatings with micro-channel cooling system using finite element analysis (FEA) to determine their feasibility as a stand-alone structural coating. During this project it was found that stiffness response to increase and remain stable to a certain level and reduce at latter stages of thermal cyclic exposure. The predominant growth and adherent Ni-rich outer oxide scale was found on top of the alumina scale throughout the oxidation cycles. The FEA analysis revealed that ODS alloys could be potential high temperature turbine coating materials if micro-channel cooling system is implemented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Huizhen; Zhao, Dian; Cui, Yuangjing, E-mail: cuiyj@zju.edu.cn

Temperature measurements and thermal mapping using luminescent MOF operating in the high-temperature range are of great interest in the micro-electronic diagnosis. In this paper, we report a thermostable Eu/Tb-mixed MOF Eu{sub 0.37}Tb{sub 0.63}-BTC-a exhibiting strong luminescence at elevated temperature, which can serve as a ratiometric luminescent thermometer for high-temperature range. The high-temperature operating range (313–473 K), high relative sensitivity and accurate temperature resolution, make such a Eu/Tb-mixed MOF useful for micro-electronic diagnosis. - Graphical abstract: A thermostable Eu/Tb-mixed MOF Eu{sub 0.37}Tb{sub 0.63}-BTC-a was developed as a ratiometric luminescent thermometers in the high-temperature range of 313–473 K. - Highlights: • Amore » thermostable Eu/Tb-codoped MOF exhibiting strong luminescent at elevated temperature is reported. • The high-temperature operating range of Eu{sub 0.37}Tb{sub 0.63}-BTC-a is 313–473 K. • The mechanism of Eu{sub 0.37}Tb{sub 0.63}-BTC-a used as thermometers are also discussed.« less

Advanced high temperature heat flux sensors

NASA Technical Reports Server (NTRS)

Atkinson, W.; Hobart, H. F.; Strange, R. R.

1983-01-01

To fully characterize advanced high temperature heat flux sensors, calibration and testing is required at full engine temperature. This required the development of unique high temperature heat flux test facilities. These facilities were developed, are in place, and are being used for advanced heat flux sensor development.

Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

DOEpatents

Westerfield, Curtis L.; Morris, John S.; Agnew, Stephen F.

1997-01-01

Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear.

Hyperscaling violating black hole solutions and magneto-thermoelectric DC conductivities in holography

NASA Astrophysics Data System (ADS)

Ge, Xian-Hui; Tian, Yu; Wu, Shang-Yu; Wu, Shao-Feng

2017-08-01

We derive new black hole solutions in Einstein-Maxwell-axion-dilaton theory with a hyperscaling violation exponent. We then examine the corresponding anomalous transport exhibited by cuprate strange metals in the normal phase of high-temperature superconductors via gauge-gravity duality. Linear-temperature-dependence resistivity and quadratic-temperature-dependence inverse Hall angle can be achieved. In the high-temperature regime, the heat conductivity and Hall Lorenz ratio are proportional to the temperature. The Nernst signal first increases as temperature goes up, but it then decreases with increasing temperature in the high-temperature regime.

High Temperature Resistant Organopolysiloxane Coating for Protecting and Repairing Rigid Thermal Insulation

NASA Technical Reports Server (NTRS)

Leiser, Daniel B. (Inventor); Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

1999-01-01

Ceramics are protected from high temperature degradation, including high temperature, oxidative, aeroconvective degradation by a high temperature and oxidation resistant coating of a room temperature curing, hydrolyzed and partially condensed liquid polyorganosiloxane to the surface of the ceramic. The liquid polyorganosiloxane is formed by the hydrolysis and partial condensation of an alkyltrialkoxysilane with water or a mixture of an alkyltrialkoxysilane and a dialkyldialkoxysilane with water. The liquid polyorganosiloxane cures at room temperature on the surface of the ceramic to form a hard, protective, solid coating which forms a high temperature environment, and is also used as an adhesive for adhering a repair plug in major damage to the ceramic. This has been found useful for protecting and repairing porous, rigid ceramics of a type used on reentry space vehicles.

High-temperature optical fiber sensors for characterization of advanced composite aerospace materials

NASA Astrophysics Data System (ADS)

Wavering, Thomas A.; Greene, Jonathan A.; Meller, Scott A.; Bailey, Timothy A.; Kozikowski, Carrie L.; Lenahan, Shannon M.; Murphy, Kent A.; Camden, Michael P.; Simmons, Larry W.

1999-01-01

Optical fiber sensors have numerous advantages over conventional sensing technologies. One such advantage is that optical fiber sensors can operate in high temperature environments. While most conventional electrical-based sensors do not operate reliably over 300 degrees C, fused silica based optical fiber sensors can survive up to 900 degrees C, and sapphire based optical fiber sensors can survive up to 2000 degrees C. Using both fused silica and sapphire technologies, we present result for high temperature strain, pressure, and temperature sensors using Extrinsic Fabry-Perot INterferometric-based and Bragg grating sensors. High temperature strain and temperature sensors were used to conduct fatigue testing of composite coupons at 600 degrees C. The results from these specific high temperature applications are presented along with future applications and directions for these sensors.

High-temperature effects on the light transmission through sapphire optical fiber

DOE PAGES

Wilson, Brandon A.; Petrie, Christian M.; Blue, Thomas E.

2018-03-13

Single crystal sapphire optical fiber was tested at high temperatures (1500°C) to determine its suitability for optical instrumentation in high-temperature environments. Broadband light transmission (450-2300 nm) through sapphire fiber was measured as a function of temperature as a test of the fiber's ability to survive and operate in high-temperature environments. Upon heating sapphire fiber to 1400°C, large amounts of light attenuation were measured across the entire range of light wavelengths that were tested. SEM and TEM images of the heated sapphire fiber indicated that a layer had formed at the surface of the fiber, most likely due to a chemicalmore » change at high temperatures. The microscopy results suggest that the surface layer may be in the form of aluminum hydroxide. Subsequent tests of sapphire fiber in an inert atmosphere showed minimal light attenuation at high temperatures along with the elimination of any surface layers on the fiber, indicating that the air atmosphere is indeed responsible for the increased attenuation and surface layer formation at high temperatures.« less

High-temperature effects on the light transmission through sapphire optical fiber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, Brandon A.; Petrie, Christian M.; Blue, Thomas E.

Single crystal sapphire optical fiber was tested at high temperatures (1500°C) to determine its suitability for optical instrumentation in high-temperature environments. Broadband light transmission (450-2300 nm) through sapphire fiber was measured as a function of temperature as a test of the fiber's ability to survive and operate in high-temperature environments. Upon heating sapphire fiber to 1400°C, large amounts of light attenuation were measured across the entire range of light wavelengths that were tested. SEM and TEM images of the heated sapphire fiber indicated that a layer had formed at the surface of the fiber, most likely due to a chemicalmore » change at high temperatures. The microscopy results suggest that the surface layer may be in the form of aluminum hydroxide. Subsequent tests of sapphire fiber in an inert atmosphere showed minimal light attenuation at high temperatures along with the elimination of any surface layers on the fiber, indicating that the air atmosphere is indeed responsible for the increased attenuation and surface layer formation at high temperatures.« less

High-Temperature Adhesives for Thermally Stable Aero-Assist Technologies

NASA Technical Reports Server (NTRS)

Eberts, Kenneth; Ou, Runqing

2013-01-01

Aero-assist technologies are used to control the velocity of exploration vehicles (EVs) when entering Earth or other planetary atmospheres. Since entry of EVs in planetary atmospheres results in significant heating, thermally stable aero-assist technologies are required to avoid the high heating rates while maintaining low mass. Polymer adhesives are used in aero-assist structures because of the need for high flexibility and good bonding between layers of polymer films or fabrics. However, current polymer adhesives cannot withstand temperatures above 400 C. This innovation utilizes nanotechnology capabilities to address this need, leading to the development of high-temperature adhesives that exhibit high thermal conductivity in addition to increased thermal decomposition temperature. Enhanced thermal conductivity will help to dissipate heat quickly and effectively to avoid temperature rising to harmful levels. This, together with increased thermal decomposition temperature, will enable the adhesives to sustain transient high-temperature conditions.

Evaluation of high temperature dielectric films for high voltage power electronic applications

NASA Technical Reports Server (NTRS)

Suthar, J. L.; Laghari, J. R.

1992-01-01

Three high temperature films, polyimide, Teflon perfluoroalkoxy and poly-P-xylene, were evaluated for possible use in high voltage power electronic applications, such as in high energy density capacitors, cables and microelectronic circuits. The dielectric properties, including permittivity and dielectric loss, were obtained in the frequency range of 50 Hz to 100 kHz at temperatures up to 200 C. The dielectric strengths at 60 Hz were determined as a function of temperature to 250 C. Confocal laser microscopy was performed to diagnose for voids and microimperfections within the film structure. The results obtained indicate that all films evaluated are capable of maintaining their high voltage properties, with minimal degradation, at temperatures up to 200 C. However, above 200 C, they lose some of their electrical properties. These films may therefore become viable candidates for high voltage power electronic applications at high temperatures.

Laser-machined microcavities for simultaneous measurement of high-temperature and high-pressure.

PubMed

Ran, Zengling; Liu, Shan; Liu, Qin; Huang, Ya; Bao, Haihong; Wang, Yanjun; Luo, Shucheng; Yang, Huiqin; Rao, Yunjiang

2014-08-07

Laser-machined microcavities for simultaneous measurement of high-temperature and high-pressure are demonstrated. These two cascaded microcavities are an air cavity and a composite cavity including a section of fiber and an air cavity. They are both placed into a pressure chamber inside a furnace to perform simultaneous pressure and high-temperature tests. The thermal and pressure coefficients of the short air cavity are ~0.0779 nm/°C and ~1.14 nm/MPa, respectively. The thermal and pressure coefficients of the composite cavity are ~32.3 nm/°C and ~24.4 nm/MPa, respectively. The sensor could be used to separate temperature and pressure due to their different thermal and pressure coefficients. The excellent feature of such a sensor head is that it can withstand high temperatures of up to 400 °C and achieve precise measurement of high-pressure under high temperature conditions.

Simulation of the real efficiencies of high-efficiency silicon solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sachenko, A. V., E-mail: sach@isp.kiev.ua; Skrebtii, A. I.; Korkishko, R. M.

The temperature dependences of the efficiency η of high-efficiency solar cells based on silicon are calculated. It is shown that the temperature coefficient of decreasing η with increasing temperature decreases as the surface recombination rate decreases. The photoconversion efficiency of high-efficiency silicon-based solar cells operating under natural (field) conditions is simulated. Their operating temperature is determined self-consistently by simultaneously solving the photocurrent, photovoltage, and energy-balance equations. Radiative and convective cooling mechanisms are taken into account. It is shown that the operating temperature of solar cells is higher than the ambient temperature even at very high convection coefficients (~300 W/m{sup 2}more » K). Accordingly, the photoconversion efficiency in this case is lower than when the temperature of the solar cells is equal to the ambient temperature. The calculated dependences for the open-circuit voltage and the photoconversion efficiency of high-quality silicon solar cells under concentrated illumination are discussed taking into account the actual temperature of the solar cells.« less

Exogenously Applied Plant Growth Regulators Enhance the Morpho-Physiological Growth and Yield of Rice under High Temperature.

PubMed

Fahad, Shah; Hussain, Saddam; Saud, Shah; Hassan, Shah; Ihsan, Zahid; Shah, Adnan N; Wu, Chao; Yousaf, Muhammad; Nasim, Wajid; Alharby, Hesham; Alghabari, Fahad; Huang, Jianliang

2016-01-01

A 2-year experiment was conducted to ascertain the effects of exogenously applied plant growth regulators (PGR) on rice growth and yield attributes under high day (HDT) and high night temperature (HNT). Two rice cultivars (IR-64 and Huanghuazhan) were subjected to temperature treatments in controlled growth chambers and four different combinations of ascorbic acid (Vc), alpha-tocopherol (Ve), brassinosteroids (Br), methyl jasmonates (MeJA), and triazoles (Tr) were applied. High temperature severely affected rice morphology, and also reduced leaf area, above-, and below-ground biomass, photosynthesis, and water use efficiency, while increased the leaf water potential of both rice cultivars. Grain yield and its related attributes except number of panicles, were reduced under high temperature. The HDT posed more negative effects on rice physiological attributes, while HNT was more detrimental for grain formation and yield. The Huanghuazhan performed better than IR-64 under high temperature stress with better growth and higher grain yield. Exogenous application of PGRs was helpful in alleviating the adverse effects of high temperature. Among PGR combinations, the Vc+Ve+MejA+Br was the most effective treatment for both cultivars under high temperature stress. The highest grain production by Vc+Ve+MejA+Br treated plants was due to enhanced photosynthesis, spikelet fertility and grain filling, which compensated the adversities of high temperature stress. Taken together, these results will be of worth for further understanding the adaptation and survival mechanisms of rice to high temperature and will assist in developing heat-resistant rice germplasm in future.

Generating high temperature tolerant transgenic plants: Achievements and challenges.

PubMed

Grover, Anil; Mittal, Dheeraj; Negi, Manisha; Lavania, Dhruv

2013-05-01

Production of plants tolerant to high temperature stress is of immense significance in the light of global warming and climate change. Plant cells respond to high temperature stress by re-programming their genetic machinery for survival and reproduction. High temperature tolerance in transgenic plants has largely been achieved either by over-expressing heat shock protein genes or by altering levels of heat shock factors that regulate expression of heat shock and non-heat shock genes. Apart from heat shock factors, over-expression of other trans-acting factors like DREB2A, bZIP28 and WRKY proteins has proven useful in imparting high temperature tolerance. Besides these, elevating the genetic levels of proteins involved in osmotic adjustment, reactive oxygen species removal, saturation of membrane-associated lipids, photosynthetic reactions, production of polyamines and protein biosynthesis process have yielded positive results in equipping transgenic plants with high temperature tolerance. Cyclic nucleotide gated calcium channel proteins that regulate calcium influxes across the cell membrane have recently been shown to be the key players in induction of high temperature tolerance. The involvement of calmodulins and kinases in activation of heat shock factors has been implicated as an important event in governing high temperature tolerance. Unfilled gaps limiting the production of high temperature tolerant transgenic plants for field level cultivation are discussed. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

High temperature superconducting fault current limiter

DOEpatents

Hull, J.R.

1997-02-04

A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.

High Temperature Silicon Carbide (SiC) Traction Motor Drive

DTIC Science & Technology

2011-08-09

UNCLASSIFIED Distribution Statement A. Approved for public release; distribution is unlimited. UNCLASSIFIED HIGH TEMPERATURE SILICON CARBIDE...be modular and conveniently distributed. Small component size and operation with high - temperature liquid coolant are essential factors in the...these densities, power modules capable of high - temperature operation were developed using SiC normally-off JFETs. This paper will discuss the unique

Conical Magnetic Bearing Development and Magnetic Bearing Testing for Extreme Temperature Environments

NASA Technical Reports Server (NTRS)

Keith, Theo G., Jr.; Jansen, Mark

2004-01-01

The main proposed research of this grant were: to design a high-temperature, conical magnetic bearing facility, to test the high-temperature, radial magnetic bearing facility to higher speeds, to investigate different backup bearing designs and materials, to retrofit the high-temperature test facility with a magnetic thrust bearing, to evaluate test bearings at various conditions, and test several lubricants using a spiral orbit tribometer. A high-temperature, conical magnetic bearing facility has been fully developed using Solidworks. The facility can reuse many of the parts of the current high-temperature, radial magnetic bearing, helping to reduce overall build costs. The facility has the ability to measure bearing force capacity in the X, Y, and Z directions through a novel bearing mounting design. The high temperature coils and laminations, a main component of the facility, are based upon the current radial design and can be fabricated at Texas A&M University. The coil design was highly successful in the radial magnetic bearing. Vendors were contacted about fabrication of the high temperature lamination stack. Stress analysis was done on the laminations. Some of the components were procured, but due to budget cuts, the facility build up was stopped.

Cycle analysis of planar SOFC power generation with serial connection of low and high temperature SOFCs

NASA Astrophysics Data System (ADS)

Araki, Takuto; Ohba, Takahiro; Takezawa, Shinya; Onda, Kazuo; Sakaki, Yoshinori

Solid oxide fuel cells (SOFCs) can be composed of solid components for stable operation, and high power generation efficiency is obtained by using high temperature exhaust heat for fuel reforming and bottoming power generation by a gas turbine. Recently, low-temperature SOFCs, which run in the temperature range of around 600 °C or above and give high power generation efficiency, have been developed. On the other hand, a power generation system with multi-staged fuel cells has been proposed by the United States DOE to obtain high efficiency. In our present study, a power generation system consisting of two-staged SOFCs with serial connection of low and high temperature SOFCs was investigated. Overpotential data for the low-temperature SOFC used in this study are based on recently published data, while data for high-temperature SOFC are based on our previous study. The numerical results show that the power generation efficiency of the two-staged SOFCs is 50.3% and the total efficiency of power generation with gas turbine is 56.1% under standard operating conditions. These efficiencies are a little higher than those by high-temperature SOFC only.

Silicon Carbide Nanotube Oxidation at High Temperatures

NASA Technical Reports Server (NTRS)

Ahlborg, Nadia; Zhu, Dongming

2012-01-01

Silicon Carbide Nanotubes (SiCNTs) have high mechanical strength and also have many potential functional applications. In this study, SiCNTs were investigated for use in strengthening high temperature silicate and oxide materials for high performance ceramic nanocomposites and environmental barrier coating bond coats. The high · temperature oxidation behavior of the nanotubes was of particular interest. The SiCNTs were synthesized by a direct reactive conversion process of multiwall carbon nanotubes and silicon at high temperature. Thermogravimetric analysis (TGA) was used to study the oxidation kinetics of SiCNTs at temperatures ranging from 800degC to1300degC. The specific oxidation mechanisms were also investigated.

High-temperature testing of glass/ceramic matrix composites

NASA Technical Reports Server (NTRS)

Mandell, John F.; Grande, Dodd H.; Dannemann, Kathryn A.

1989-01-01

Recent advances in ceramic and other high-temperature composites have created a need for test methods that can be used at 1000 C and above. Present test methods usually require adhesively bonded tabs that cannot be used at high temperatures. This paper discusses some of the difficulties with high-temperature test development and describes several promising test methods. Stress-strain data are given for Nicalon ceramic fiber reinforced glass and glass-ceramic matrix composites tested in air at temperatures up to 1000 C.

In Situ Observation of Gypsum-Anhydrite Transition at High Pressure and High Temperature

NASA Astrophysics Data System (ADS)

Liu, Chuan-Jiang; Zheng, Hai-Fei

2012-04-01

An in-situ Raman spectroscopic study of gypsum-anhydrite transition under a saturated water condition at high pressure and high temperature is performed using a hydrothermal diamond anvil cell (HDAC). The experimental results show that gypsum dissolvs in water at ambient temperature and above 496 MPa. With increasing temperature, the anhydrite (CaSO4) phase precipitates at 250-320°C in the pressure range of 1.0-1.5GPa, indicating that under a saturated water condition, both stable conditions of pressure and temperature and high levels of Ca and SO4 ion concentrations in aqueous solution are essential for the formation of anhydrite. A linear relationship between the pressure and temperature for the precipitation of anhydrite is established as P(GPa) = 0.0068T-0.7126 (250°C<=T<=320°C). Anhydrite remained stable during rapid cooling of the sample chamber, showing that the gypsum-anhydrite transition involving both dissolution and precipitation processes is irreversible at high pressure and high temperature.

Fabrication and modeling of bismuth titanate-PZT ceramic transducers for high temperature applications

NASA Astrophysics Data System (ADS)

Reinhardt, B.; Searfass, C.; Cyphers, R.; Sinding, K.; Pheil, C.; Tittmann, B.

2013-01-01

Utilization of a spray-on deposition technique of ferroelectric bismuth titanate (Bi4Ti3O12) composites has a competitive advantage to standard ultrasonic transducers. These can conform to curved surfaces, can operate at high temperature (Curie-Weiss temperature 685 °C) and are mechanically well-coupled to a substrate. However, an issue with many high temperature transducers such as bismuth titanate ceramics is that they have relatively low transduction efficiency, i.e. d33 is about 12-14 pC/F in Bi4Ti3O12 versus 650 pC/F in PZT-5H. It is a common conception that high-temperature capability comes at the cost of electro-mechanical coupling. It will be shown that the high temperature capability of bismuth-titanate-PZT composite transducers using the spray-on deposition technique previously developed, improves the electro-mechanical coupling while maintaining the high temperature performance and mechanical coupling. This material could provide advantages in harsh environments where high signal-to-noise ratios are needed.

Three-Dimensional Printable High-Temperature and High-Rate Heaters.

PubMed

Yao, Yonggang; Fu, Kun Kelvin; Yan, Chaoyi; Dai, Jiaqi; Chen, Yanan; Wang, Yibo; Zhang, Bilun; Hitz, Emily; Hu, Liangbing

2016-05-24

High temperature heaters are ubiquitously used in materials synthesis and device processing. In this work, we developed three-dimensional (3D) printed reduced graphene oxide (RGO)-based heaters to function as high-performance thermal supply with high temperature and ultrafast heating rate. Compared with other heating sources, such as furnace, laser, and infrared radiation, the 3D printed heaters demonstrated in this work have the following distinct advantages: (1) the RGO based heater can operate at high temperature up to 3000 K because of using the high temperature-sustainable carbon material; (2) the heater temperature can be ramped up and down with extremely fast rates, up to ∼20 000 K/second; (3) heaters with different shapes can be directly printed with small sizes and onto different substrates to enable heating anywhere. The 3D printable RGO heaters can be applied to a wide range of nanomanufacturing when precise temperature control in time, placement, and the ramping rate are important.

High skin temperature and hypohydration impair aerobic performance.

PubMed

Sawka, Michael N; Cheuvront, Samuel N; Kenefick, Robert W

2012-03-01

This paper reviews the roles of hot skin (>35°C) and body water deficits (>2% body mass; hypohydration) in impairing submaximal aerobic performance. Hot skin is associated with high skin blood flow requirements and hypohydration is associated with reduced cardiac filling, both of which act to reduce aerobic reserve. In euhydrated subjects, hot skin alone (with a modest core temperature elevation) impairs submaximal aerobic performance. Conversely, aerobic performance is sustained with core temperatures >40°C if skin temperatures are cool-warm when euhydrated. No study has demonstrated that high core temperature (∼40°C) alone, without coexisting hot skin, will impair aerobic performance. In hypohydrated subjects, aerobic performance begins to be impaired when skin temperatures exceed 27°C, and even warmer skin exacerbates the aerobic performance impairment (-1.5% for each 1°C skin temperature). We conclude that hot skin (high skin blood flow requirements from narrow skin temperature to core temperature gradients), not high core temperature, is the 'primary' factor impairing aerobic exercise performance when euhydrated and that hypohydration exacerbates this effect.

Evidence for a high temperature differentiation in a molten earth: A preliminary appraisal

NASA Technical Reports Server (NTRS)

Murthy, V. Rama

1992-01-01

If the earth were molten during its later stages of accretion as indicated by the present understanding of planetary accretion process, the differentiation that led to the formation of the core and mantle must have occurred at high temperatures in the range of 3000-5000 K because of the effect of pressure on the temperature of melting in the interior of the earth. This calls into question the use of low-temperature laboratory measurements of partition coefficients of trace elements to make inferences about earth accretion and differentiation. The low temperature partition coefficients cannot be directly applied to high temperature fractionations because partition coefficients refer to an equilibrium specific to a temperature for a given reaction, and must change in some proportion to exp 1/RT. There are no laboratory data on partition coefficients at the high temperatures relevant to differentiation in the interior of the earth, and an attempt to estimate high temperature distribution coefficients of siderophile elements was made by considering the chemical potential of a given element at equilibrium and how this potential changes with temperature, under some specific assumptions.

Development of high temperature acoustic emission sensing system using fiber Bragg grating

NASA Astrophysics Data System (ADS)

Pang, Dandan; Sui, Qingmei; Wang, Ming; Guo, Dongmei; Sai, Yaozhang

2018-03-01

In some applications in structural health monitoring (SHM), the acoustic emission (AE) detection technology is used in the high temperature environment. In this paper, a high-temperature-resistant AE sensing system is developed based on the fiber Bragg grating (FBG) sensor. A novel high temperature FBG AE sensor is designed with a high signal-to-noise ratio (SNR) compared with the traditional FBG AE sensor. The output responses of the designed sensors with different sensing fiber lengths also are investigated both theoretically and experimentally. Excellent AE detection results are obtained using the proposed FBG AE sensing system over a temperature range from 25 ° to 200 °. The experimental results indicate that this FBG AE sensing system can well meet the application requirement in AE detecting areas at high temperature.

Safe and Durable High-Temperature Lithium-Sulfur Batteries via Molecular Layer Deposited Coating.

PubMed

Li, Xia; Lushington, Andrew; Sun, Qian; Xiao, Wei; Liu, Jian; Wang, Biqiong; Ye, Yifan; Nie, Kaiqi; Hu, Yongfeng; Xiao, Qunfeng; Li, Ruying; Guo, Jinghua; Sham, Tsun-Kong; Sun, Xueliang

2016-06-08

Lithium-sulfur (Li-S) battery is a promising high energy storage candidate in electric vehicles. However, the commonly employed ether based electrolyte does not enable to realize safe high-temperature Li-S batteries due to the low boiling and flash temperatures. Traditional carbonate based electrolyte obtains safe physical properties at high temperature but does not complete reversible electrochemical reaction for most Li-S batteries. Here we realize safe high temperature Li-S batteries on universal carbon-sulfur electrodes by molecular layer deposited (MLD) alucone coating. Sulfur cathodes with MLD coating complete the reversible electrochemical process in carbonate electrolyte and exhibit a safe and ultrastable cycle life at high temperature, which promise practicable Li-S batteries for electric vehicles and other large-scale energy storage systems.

Torsional ultrasonic wave based level measurement system

DOEpatents

Holcomb, David E [Oak Ridge, TN; Kisner, Roger A [Knoxville, TN

2012-07-10

A level measurement system suitable for use in a high temperature and pressure environment to measure the level of coolant fluid within the environment, the system including a volume of coolant fluid located in a coolant region of the high temperature and pressure environment and having a level therein; an ultrasonic waveguide blade that is positioned within the desired coolant region of the high temperature and pressure environment; a magnetostrictive electrical assembly located within the high temperature and pressure environment and configured to operate in the environment and cooperate with the waveguide blade to launch and receive ultrasonic waves; and an external signal processing system located outside of the high temperature and pressure environment and configured for communicating with the electrical assembly located within the high temperature and pressure environment.