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Sample records for electrolyzed water ice

  1. Application of neutral electrolyzed water to disinfection of alginate impression.

    Science.gov (United States)

    Nagamatsu, Yuki; Chen, Ker-Kong; Nagamatsu, Hiroshi; Kozono, Yoshio; Shimizu, Hiroshi

    2016-01-01

    Neutral electrolyzed water was developed with new concepts of long-term good durability and minimum corrosiveness to metal in addition to its excellent bactericidal activities similar to acid type of electrolyzed waters. The present study examined the bactericidal effects of the neutral electrolyzed water on disinfection of the alginate impression of a dental arch model contaminated by bacteria. Only 1-min immersion in neutral electrolyzed water could sufficiently disinfect the alginate impression including the metallic tray under ultrasonic with no significant differences from acid electrolyzed waters. No bactericidal effects were found in any electrolyzed water when used as mixing water. Considering the advantages and disadvantages of each electrolyzed water in a comprehensive way, it was suggested that neutral electrolyzed water may be the most appropriate for the disinfection of alginate impression.

  2. USE OF ELECTROLYZED WATER IN ANIMAL PRODUCTION

    Directory of Open Access Journals (Sweden)

    Dana Jirotková

    2012-10-01

    Full Text Available The paper deals with the possibility to use the properties of electrolyzed water to disinfect breeding halls and to water animals. The aim of the research was to find out whether elektrolyzed water used for desinfication of breedings hall and watering of animals influences selected indicators of the meat quality. Electrolyzed water is produced in a patent-protected device Envirolyte that produces biocide solution using potable water with added NaCl. The technology of production guarantees the product is entirely ecological, biologically fully degradable, non-toxic that can replace traditional chemical agents. Possibilities of disinfection using this solution have been verified directly in stables at the interval of 20, 40, 60 min. after application. Staphylococci and streptococci and enterococci were inactive always after 60 minutes of effect. There was significant decrease in the number of total number of microorganisms. Further, the solution of electrolyzed water was used to water poultry; and the affect on some of the properties of poultry meat, changes in pH, colour and loss of water (dripping in particular, was observed. Testing was carried out under working conditions in two breeding halls at a time and the technology of electrolyzed water to disinfect premises and to water chickens was used in one of the halls. When the chickens were slaughter mature, the poultry was slaughtered at the standard slaughterhouse and samples (127 pieces were taken in order to measure pH, colour and loss of water (dripping. The values of pH, colour and loss of water (dripping ascertained, processed by the T-test did not confirm the hypothesis of the assumed possible differences in occurrence of critical values of these indicators in both groups observed.

  3. Superconductor made by electrolyzed and oxidized water

    OpenAIRE

    Liu, Chia-Jyi; Wu, Tsung-Hsien; Hsu, Lin-Li; Wang, Jung-Sheng; Chen, Shu-Yo; Chang, Wei Jen; Lin, Jiunn-Yuan

    2006-01-01

    By deintercalation of Na+ followed by inserting bilayers of water molecules into the host lattice, the layered cobalt oxide of gamma-Na0.7CoO2 undergoes a topotactic transformation to a layered cobalt oxyhydrate of Na0.35(H2O)1.3CoO2-delta with the c-axis expanded from c = 10.9 anstrom to c = 19.6 anstrom. In this paper, we demonstrate that the superconducting phase of c = 19.6 anstrom can be directly obtained by simply immersing gamma-Na0.7CoO2 powders in electrolyzed/oxidized (EO) water, wh...

  4. Development of device producing electrolyzed water for home care

    International Nuclear Information System (INIS)

    Umimoto, K; Nagata, S; Yanagida, J

    2013-01-01

    When water containing ionic substances is electrolyzed, electrolyzed water with strong bactericidal ability due to the available chlorine(AC) is generated on the anode side. Slightly acidic to neutral electrolyzed water (pH 6.5 to 7.5) is physiological pH and is suitable for biological applications. For producing slightly acidic to neutral electrolyzed water simply, a vertical-type electrolytic tank with an asymmetric structure was made. As a result, a small amount of strongly alkaline water was generated in the upper cathodic small chamber, and a large amount of weakly acidic water generated in the lower anodic large chamber. The pH and AC concentration in solutin mixed with both electrolyzed water were 6.3 and 39.5 ppm, respectively, This solution was slightly acidic to neutral electrolyzed water and had strong bactericidal activity. This device is useful for producing slightly acidic to neutral electrolyzed water as a disinfectant to employ at home care, when considering economic and environmental factors, since it returns to ordinary water after use.

  5. Effect of electrolyzed reduced water on malondialdehyde levels and ...

    African Journals Online (AJOL)

    Purpose: To evaluate the effects of electrolyzed reduced water (ERW) on .... dehydrated and cleared with alcohol. ... assay tubes were incubated at a temperature of ... oxygen-dependent and oxygen-independent .... Oxidative Medicine and.

  6. Universal cell frame for high-pressure water electrolyzer and electrolyzer including the same

    Science.gov (United States)

    Schmitt, Edwin W.; Norman, Timothy J.

    2013-01-08

    Universal cell frame generic for use as an anode frame and as a cathode frame in a water electrolyzer. According to one embodiment, the universal cell frame includes a unitary annular member having a central opening. Four trios of transverse openings are provided in the annular member, each trio being spaced apart by about 90 degrees. A plurality of internal radial passageways fluidly interconnect the central opening and each of the transverse openings of two diametrically-opposed trios of openings, the other two trios of openings lacking corresponding radial passageways. Sealing ribs are provided on the top and bottom surfaces of the annular member. The present invention is also directed at a water electrolyzer that includes two such cell frames, one being used as the anode frame and the other being used as the cathode frame, the cathode frame being rotated 90 degrees relative to the anode frame.

  7. Electrolyzed water and its application in animal houses

    Directory of Open Access Journals (Sweden)

    Weichao ZHENG,Li NI,Baoming LI

    2016-09-01

    Full Text Available Electrolyzed water (EW can be produced by electrolysis of a dilute salt solution. Slightly acidic electrolyzed water (SAEW, pH 5.0—6.5 and neutral electrolyzed water (NEW, pH 6.5—8.5 are considered healthy and environmentally friendly because no hazardous chemicals are added in its production, there is reduced corrosion of surfaces and it minimizes the potential for damage to animal and human health. Over the last decade, EW has become increasingly popular as an alternative disinfectant for decontamination in animal houses. However, there have been some issues related to EW that are not well known, including different mechanisms for generation of SAEW and NEW, and the antimicrobial mechanism of EW. This review covers the definitions of SAEW and NEW, different generation systems for SAEW and NEW, the antimicrobial mecha- nism of EW, and recent developments related to the application of SAEW and NEW in animal houses.

  8. Effect of electrolyzed reduced water on malondialdehyde levels and ...

    African Journals Online (AJOL)

    Purpose: To evaluate the effects of electrolyzed reduced water (ERW) on malondialdehyde (MDA) levels and neutrophil cells in Wistar rats suffering from aggressive periodontitis. Methods: Wistar rats (Rattus norvegicus) were infected with A. actinomycetemcomitans before being divided into a control group and a treatment ...

  9. Electrolyzed water and its application in the food industry.

    Science.gov (United States)

    Hricova, D; Stephan, R; Zweifel, C

    2008-09-01

    Electrolyzed water (EW) is gaining popularity as a sanitizer in the food industries of many countries. By electrolysis, a dilute sodium chloride solution dissociates into acidic electrolyzed water (AEW), which has a pH of 2 to 3, an oxidation-reduction potential of >1,100 mV, and an active chlorine content of 10 to 90 ppm, and basic electrolyzed water (BEW), which has a pH of 10 to 13 and an oxidation-reduction potential of -800 to -900 mV. Vegetative cells of various bacteria in suspension were generally reduced by > 6.0 log CFU/ml when AEW was used. However, AEW is a less effective bactericide on utensils, surfaces, and food products because of factors such as surface type and the presence of organic matter. Reductions of bacteria on surfaces and utensils or vegetables and fruits mainly ranged from about 2.0 to 6.0 or 1.0 to 3.5 orders of magnitude, respectively. Higher reductions were obtained for tomatoes. For chicken carcasses, pork, and fish, reductions ranged from about 0.8 to 3.0, 1.0 to 1.8, and 0.4 to 2.8 orders of magnitude, respectively. Considerable reductions were achieved with AEW on eggs. On some food commodities, treatment with BEW followed by AEW produced higher reductions than did treatment with AEW only. EW technology deserves consideration when discussing industrial sanitization of equipment and decontamination of food products. Nevertheless, decontamination treatments for food products always should be considered part of an integral food safety system. Such treatments cannot replace strict adherence to good manufacturing and hygiene practices.

  10. Development of a pressurized bipolar alkaline water electrolyzer

    Energy Technology Data Exchange (ETDEWEB)

    Neves Junior, Newton Pimenta; Pinto, Edgar A. de Godoi Rodrigues; Silva, Ennio Peres da; Rapelli, Rubia; Pinto, Cristiano da Silva [Universidade Estadual de Campinas (DFA/ IFGW/UNICAMP), SP (Brazil). Inst. de Fisica Gleb Wataghin. Dept. de Fisica Aplicada], Email: nevesjr@unicamp.br; Marin Neto, Antonio Jose; Lopes, Daniel Gabriel; Camargo, Joao Carlos; Ferreira, Paulo F.P. [Hydrogen Technology (HyTron), Campinas, SP (Brazil); Furlan, Andre Luis [Universidade Estadual de Campinas (DE/FEC/UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica

    2010-07-01

    This paper reports the actual development status of a bipolar alkaline water electrolyzer with maximum production capacity of 1 m3/h of hydrogen and controlled by a PLC (Programmable Logic Controller), which also interfaces the electrolytic system with operators and other equipment, such as gas storage tanks, fuel cells and photovoltaic panels. The project also includes the construction of an electrolysis test bench to record electrical parameters (cathode, anode, separator and electrolyte potentials), the amount of produced gases and gas quality determined by gas chromatography. (author)

  11. Effects of electrolysis time and electric potential on chlorine generation of electrolyzed deep ocean water

    Directory of Open Access Journals (Sweden)

    Guoo-Shyng Wang Hsu

    2017-10-01

    Full Text Available Electrolyzed water is a sustainable disinfectant, which can comply with food safety regulations and is environmentally friendly. A two-factor central composite design was adopted for studying the effects of electrolysis time and electric potential on the chlorine generation efficiency of electrolyzed deep ocean water (DOW. DOW was electrolyzed in a glass electrolyzing cell equipped with platinum–plated titanium anode and cathode. The results showed that chlorine concentration reached maximal level in the batch process. Prolonged electrolysis reduced chlorine concentration in the electrolyte and was detrimental to electrolysis efficiency, especially under high electric potential conditions. Therefore, the optimal choice of electrolysis time depends on the electrolyzable chloride in DOW and cell potential adopted for electrolysis. The higher the electric potential, the faster the chlorine level reaches its maximum, but the lower the electric efficiency will be.

  12. Effects of electrolysis time and electric potential on chlorine generation of electrolyzed deep ocean water.

    Science.gov (United States)

    Hsu, Guoo-Shyng Wang; Lu, Yi-Fa; Hsu, Shun-Yao

    2017-10-01

    Electrolyzed water is a sustainable disinfectant, which can comply with food safety regulations and is environmentally friendly. A two-factor central composite design was adopted for studying the effects of electrolysis time and electric potential on the chlorine generation efficiency of electrolyzed deep ocean water (DOW). DOW was electrolyzed in a glass electrolyzing cell equipped with platinum-plated titanium anode and cathode. The results showed that chlorine concentration reached maximal level in the batch process. Prolonged electrolysis reduced chlorine concentration in the electrolyte and was detrimental to electrolysis efficiency, especially under high electric potential conditions. Therefore, the optimal choice of electrolysis time depends on the electrolyzable chloride in DOW and cell potential adopted for electrolysis. The higher the electric potential, the faster the chlorine level reaches its maximum, but the lower the electric efficiency will be. Copyright © 2016. Published by Elsevier B.V.

  13. Effect of water electrolysis temperature of hydrogen production system using direct coupling photovoltaic and water electrolyzer

    Directory of Open Access Journals (Sweden)

    Tetsuhiko Maeda

    2016-01-01

    Full Text Available We propose control methods of a photovoltaic (PV-water electrolyzer (ELY system that generates hydrogen by controlling the number of ELY cells. The advantage of this direct coupling between PV and ELY is that the power loss of DC/DC converter is avoided. In this study, a total of 15 ELY cells are used. In the previous researches, the electrolyzer temperature was constantly controlled with a thermostat. Actually, the electrolyzer temperature is decided by the balance of the electrolysis loss and the heat loss to the outside. Here, the method to control the number of ELY cells was investigated. Maximum Power Point Tracking efficiency of more than 96% was achieved without ELY temperature control. Furthermore we construct a numerical model taking into account of ELY temperature. Using this model, we performed a numerical simulation of 1-year. Experimental data and the simulation results shows the validity of the proposed control method.

  14. Removal of Foodborne Pathogen Biofilms by Acidic Electrolyzed Water

    Directory of Open Access Journals (Sweden)

    Qiao Han

    2017-06-01

    Full Text Available Biofilms, which are complex microbial communities embedded in the protective extracellular polymeric substances (EPS, are difficult to remove in food production facilities. In this study, the use of acidic electrolyzed water (AEW to remove foodborne pathogen biofilms was evaluated. We used a green fluorescent protein-tagged Escherichia coli for monitoring the efficiency of AEW for removing biofilms, where under the optimal treatment conditions, the fluorescent signal of cells in the biofilm disappeared rapidly and the population of biofilm cells was reduced by more than 67%. Additionally, AEW triggered EPS disruption, as indicated by the deformation of the carbohydrate C-O-C bond and deformation of the aromatic rings in the amino acids tyrosine and phenylalanine. These deformations were identified by EPS chemical analysis and Raman spectroscopic analysis. Scanning electron microscopy (SEM images confirmed that the breakup and detachment of biofilm were enhanced after AEW treatment. Further, AEW also eradicated biofilms formed by both Gram-negative bacteria (Vibrio parahaemolyticus and Gram-positive bacteria (Listeria monocytogenes and was observed to inactivate the detached cells which are a potential source of secondary pollution. This study demonstrates that AEW could be a reliable foodborne pathogen biofilm disrupter and an eco-friendly alternative to sanitizers traditionally used in the food industry.

  15. Modelling electrolyte conductivity in a water electrolyzer cell

    DEFF Research Database (Denmark)

    Caspersen, Michael; Kirkegaard, Julius Bier

    2012-01-01

    An analytical model describing the hydrogen gas evolution under natural convection in an electrolyzer cell is developed. Main purpose of the model is to investigate the electrolyte conductivity through the cell under various conditions. Cell conductivity is calculated from a parallel resistor...

  16. Electrolyzed-water generator 'SaniBoy'; Eisei jokinsuik kyokyu sochi 'SaniBoy'

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, M; Kakiuchi, H; Muto, K [Fuji Electric Co. Ltd., Tokyo (Japan)

    2000-03-10

    In the food industry, injuries due to food poisoning have been increasing. Especially the mass outbreak of food poisoning by Escherichia coli such as O-157 in 1996 gave warning on the importance of food sanitation management. Public efforts such as the Hazard Analysis and Critical Control Point (HACCP) system have been made to prevent food poisoning. Recently, disinfection made by electrolyzing water with some salt added has attracted attention. Fuji Electric has developed the generator 'SaniBoy' that produces weak alkaline electrolyzed water without wasting water. The environment-friendly 'SaniBoy' will contribute to sanitation in various fields. (author)

  17. Real-Time Microscopic Monitoring of Flow, Voltage and Current in the Proton Exchange Membrane Water Electrolyzer.

    Science.gov (United States)

    Lee, Chi-Yuan; Li, Shih-Chun; Chen, Chia-Hung; Huang, Yen-Ting; Wang, Yu-Syuan

    2018-03-15

    Looking for alternative energy sources has been an inevitable trend since the oil crisis, and close attentioned has been paid to hydrogen energy. The proton exchange membrane (PEM) water electrolyzer is characterized by high energy efficiency, high yield, simple system and low operating temperature. The electrolyzer generates hydrogen from water free of any carbon sources (provided the electrons come from renewable sources such as solar and wind), so it is very clean and completely satisfies the environmental requirement. However, in long-term operation of the PEM water electrolyzer, the membrane material durability, catalyst corrosion and nonuniformity of local flow, voltage and current in the electrolyzer can influence the overall performance. It is difficult to measure the internal physical parameters of the PEM water electrolyzer, and the physical parameters are interrelated. Therefore, this study uses micro-electro-mechanical systems (MEMS) technology to develop a flexible integrated microsensor; internal multiple physical information is extracted to determine the optimal working parameters for the PEM water electrolyzer. The real operational data of local flow, voltage and current in the PEM water electrolyzer are measured simultaneously by the flexible integrated microsensor, so as to enhance the performance of the PEM water electrolyzer and to prolong the service life.

  18. Sequential Washing with Electrolyzed Alkaline and Acidic Water Effectively Removes Pathogens from Metal Surfaces.

    Directory of Open Access Journals (Sweden)

    Yuichiro Nakano

    Full Text Available Removal of pathogenic organisms from reprocessed surgical instruments is essential to prevent iatrogenic infections. Some bacteria can make persistent biofilms on medical devices. Contamination of non-disposable equipment with prions also represents a serious risk to surgical patients. Efficient disinfection of prions from endoscopes and other instruments such as high-resolution cameras remains problematic because these instruments do not tolerate aggressive chemical or heat treatments. Herein, we develop a new washing system that uses both the alkaline and acidic water produced by electrolysis. Electrolyzed acidic water, containing HCl and HOCl as active substances, has been reported to be an effective disinfectant. A 0.15% NaCl solution was electrolyzed and used immediately to wash bio-contaminated stainless steel model systems with alkaline water (pH 11.9 with sonication, and then with acidic water (pH 2.7 without sonication. Two bacterial species (Staphylococcus aureus and Pseudomonas aeruginosa and a fungus (Candida albicans were effectively removed or inactivated by the washing process. In addition, this process effectively removed or inactivated prions from the stainless steel surfaces. This washing system will be potentially useful for the disinfection of clinical devices such as neuroendoscopes because electrolyzed water is gentle to both patients and equipment and is environmentally sound.

  19. Physicochemical Properties of Edible Chitosan/Hydroxypropyl Methylcellulose/Lysozyme Films Incorporated with Acidic Electrolyzed Water

    Directory of Open Access Journals (Sweden)

    Ewa Brychcy

    2015-01-01

    Full Text Available The treatment with acidic electrolyzed water (AEW is a promising disinfection method due to its effectiveness in reducing microbial population. The aim of the study was to evaluate physicochemical properties of chitosan/HPMC films incorporated with lysozyme and acidic electrolyzed water. In the composite films, decreasing film solubility and increasing concentration of sodium chloride solution and prolongation of electrolysis time were observed. Electrolysis process with sodium chloride induces spongy network of film structure. The use of AEW has not changed chemical composition of films which was proved by 1H NMR, MALDI-TOF, and FT-IR spectroscopy. The research confirmed that electrolysis significantly improved thermomechanical properties of the examined films. The contact angle values of the films were quite similar and ranged between 56° and 73°. The increase of salt concentration used in the electrolysis process had an impact on increasing flexibility of samples. Application of electrolyzed water in commonly used food processing systems is possible. Fusion of AEW and biopolymers may provide better integration with coated food product and multidirectional protecting effect.

  20. Physicochemical and Antibacterial Properties of Carrageenan and Gelatine Hydrosols and Hydrogels Incorporated with Acidic Electrolyzed Water

    Directory of Open Access Journals (Sweden)

    Ewa Brychcy

    2015-12-01

    Full Text Available The article focuses on investigation of the effects of usage of acidic electrolyzed water (AEW with different sodium chloride concentration (0.001%, 0.01%, and 0.1% for the preparation of carrageenan and gelatine hydrosols and hydrogels. To determine physiochemical properties of hydrosols, the pH, oxidation-reduction potential (ORP, available chloride concentration (ACC and rheological parameters such us gelation and flow temperatures were measured. The samples were also characterized using Fourier transform infrared spectroscopy (FT IR and texture profile analysis (TPA. Additionally, the article contains an analysis of antibacterial activity of carrageenan and gelatine hydrosols incorporated with acidic electrolyzed water, against Staphylococcus aureus and Escherichia coli. The FT IR spectra demonstrated that the structure of gelatine and carrageenan are not significantly affected by electrolyzed NaCl solution components. Furthermore, TPA analysis showed that the use of AEW did not cause undesirable changes in hydrogels layer. The microbiological analysis confirmed inhibition of bacterial growth by hydrosols to about 2.10 log reduction. The results showed that the range of reduction of microorganisms depends on the type AEW used. This might be explained by the fact that the lowest pH and the highest ACC values of hydrosols were obtained for samples with the longest period of exposure to electrolysis (10 min and the highest amount of NaCl (0.1% w/v. These results suggest that hydrogels and hydrosols incorporated with AEW may be used for food preservation.

  1. Compact Water Electrolyzer for Low-Gravity Environments, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA uses a number of water electrolysis units for generating oxygen and hydrogen gas for space applications. These missions range from generating propellants to...

  2. Synthesis of superconducting cobalt oxyhydrates using a novel method: Electrolyzed and oxidized water

    International Nuclear Information System (INIS)

    Liu, C.-J.; Wu, T.-H.; Hsu, L.-L.; Wang, J.-S.; Chen, S.-Y.

    2007-01-01

    By deintercalation of Na + followed by inserting bilayers of water molecules into the host lattice, the layered cobalt oxide of γ-Na 0.7 CoO 2 undergoes a topotactic transformation to a layered cobalt oxyhydrate of Na 0.35 (H 2 O) 1.3 CoO 2-δ with the c-axis expanded from c ∼ 10.9 A to c ∼ 19.6 A. In this paper, we demonstrate that the superconducting phase of c ∼ 19.6 A can be directly obtained by simply immersing γ-Na 0.7 CoO 2 powders in electrolyzed/oxidized (EO) water, which is readily available from a commercial electrolyzed water generator. We found that high oxidation-reduction potential of EO water drives the oxidation of the cobalt ions accompanying by the formation of the superconductive c ∼ 19.6 A phase. Our results demonstrate how EO water can be used to oxidize the cobalt ions and hence form superconducting cobalt oxyhydrates in a clean and simple way and may provide an economic and environment-friendly route to oxidize the transition metal of complex metal oxides

  3. Synthesis of superconducting cobalt oxyhydrates using a novel method: Electrolyzed and oxidized water

    Science.gov (United States)

    Liu, Chia-Jyi; Wu, Tsung-Hsien; Hsu, Lin-Li; Wang, Jung-Sheng; Chen, Shu-Yo

    2007-09-01

    By deintercalation of Na+ followed by inserting bilayers of water molecules into the host lattice, the layered cobalt oxide of γ-Na0.7CoO2 undergoes a topotactic transformation to a layered cobalt oxyhydrate of Na0.35(H2O)1.3CoO2-δ with the c-axis expanded from c ≈ 10.9 Å to c ≈ 19.6 Å. In this paper, we demonstrate that the superconducting phase of c ≈ 19.6 Å can be directly obtained by simply immersing γ-Na0.7CoO2 powders in electrolyzed/oxidized (EO) water, which is readily available from a commercial electrolyzed water generator. We found that high oxidation-reduction potential of EO water drives the oxidation of the cobalt ions accompanying by the formation of the superconductive c ≈ 19.6 Å phase. Our results demonstrate how EO water can be used to oxidize the cobalt ions and hence form superconducting cobalt oxyhydrates in a clean and simple way and may provide an economic and environment-friendly route to oxidize the transition metal of complex metal oxides.

  4. Synthesis of superconducting cobalt oxyhydrates using a novel method: Electrolyzed and oxidized water

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.-J. [Department of Physics, National Changhua University of Education, Changhua 50007, Taiwan (China)], E-mail: liucj@cc.ncue.edu.tw; Wu, T.-H.; Hsu, L.-L.; Wang, J.-S.; Chen, S.-Y. [Department of Physics, National Changhua University of Education, Changhua 50007, Taiwan (China)

    2007-09-01

    By deintercalation of Na{sup +} followed by inserting bilayers of water molecules into the host lattice, the layered cobalt oxide of {gamma}-Na{sub 0.7}CoO{sub 2} undergoes a topotactic transformation to a layered cobalt oxyhydrate of Na{sub 0.35}(H{sub 2}O){sub 1.3}CoO{sub 2-{delta}} with the c-axis expanded from c {approx} 10.9 A to c {approx} 19.6 A. In this paper, we demonstrate that the superconducting phase of c {approx} 19.6 A can be directly obtained by simply immersing {gamma}-Na{sub 0.7}CoO{sub 2} powders in electrolyzed/oxidized (EO) water, which is readily available from a commercial electrolyzed water generator. We found that high oxidation-reduction potential of EO water drives the oxidation of the cobalt ions accompanying by the formation of the superconductive c {approx} 19.6 A phase. Our results demonstrate how EO water can be used to oxidize the cobalt ions and hence form superconducting cobalt oxyhydrates in a clean and simple way and may provide an economic and environment-friendly route to oxidize the transition metal of complex metal oxides.

  5. Sputtering of water ice

    International Nuclear Information System (INIS)

    Baragiola, R.A.; Vidal, R.A.; Svendsen, W.; Schou, J.; Shi, M.; Bahr, D.A.; Atteberrry, C.L.

    2003-01-01

    We present results of a range of experiments of sputtering of water ice together with a guide to the literature. We studied how sputtering depends on the projectile energy and fluence, ice growth temperature, irradiation temperature and external electric fields. We observed luminescence from the decay of H(2p) atoms sputtered by heavy ion impact, but not bulk ice luminescence. Radiolyzed ice does not sputter under 3.7 eV laser irradiation

  6. Behaviour and lifetime of electrolyzers electrolysing enriched tritium containing waste water from reprocessing

    International Nuclear Information System (INIS)

    Riedel, H.J.; Ullrich, W.

    1988-01-01

    In order to define a representative waste composition for the experimental tests, the different streams of tritiated waste water which are expected to arise from the operation of the Wackersdorf reprocessing plant were identified as well as their chemical and radiochemical composition. Results obtained by pretreatment applying distillation and the decontamination factors thus achieved will be presented, as well as data concerning the effects of the remaining contaminations in the distillate on the solid-polymer electrode and the generated hydrogen and oxygen flow of the electrolyser used operating in a neutral solution. Additional investigations were performed using a TELEDYNE electrolyzer which operates in an alkaline solution

  7. Electrolyzed-water generator 'SaniBoy'; Eisei jokinsuik kyokyu sochi 'SaniBoy'

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, M.; Kakiuchi, H.; Muto, K. [Fuji Electric Co. Ltd., Tokyo (Japan)

    2000-03-10

    In the food industry, injuries due to food poisoning have been increasing. Especially the mass outbreak of food poisoning by Escherichia coli such as O-157 in 1996 gave warning on the importance of food sanitation management. Public efforts such as the Hazard Analysis and Critical Control Point (HACCP) system have been made to prevent food poisoning. Recently, disinfection made by electrolyzing water with some salt added has attracted attention. Fuji Electric has developed the generator 'SaniBoy' that produces weak alkaline electrolyzed water without wasting water. The environment-friendly 'SaniBoy' will contribute to sanitation in various fields. (author)

  8. The application of alkaline and acidic electrolyzed water in the sterilization of chicken breasts and beef liver

    OpenAIRE

    Shimamura, Yuko; Shinke, Momoka; Hiraishi, Miki; Tsuchiya, Yusuke; Masuda, Shuichi

    2015-01-01

    Abstract The sterilization effect of a combination treatment with alkaline electrolyzed water (AlEW) and strong acidic electrolyzed water (StAEW) on fresh chicken breasts and beef liver was evaluated. Samples (1, 5, and 10?g) were inoculated with Salmonella Enteritidis NBRC3313, Escherichia coli ATCC 10798, Staphylococcus aureus FDA209P, and S.?aureus C?29 [staphylococcal enterotoxin A (SEA) productive strain] and subjected to a dipping combination treatment (4?C and 25?C for 3?min) with AlEW...

  9. Sputtering of water ice

    DEFF Research Database (Denmark)

    Baragiola, R.A.; Vidal, R.A.; Svendsen, W.

    2003-01-01

    We present results of a range of experiments of sputtering of water ice together with a guide to the literature. We studied how sputtering depends on the projectile energy and fluence, ice growth temperature, irradiation temperature and external electric fields. We observed luminescence from...

  10. Carbon Nitride Materials as Efficient Catalyst Supports for Proton Exchange Membrane Water Electrolyzers

    Directory of Open Access Journals (Sweden)

    Ana Belen Jorge

    2018-06-01

    Full Text Available Carbon nitride materials with graphitic to polymeric structures (gCNH were investigated as catalyst supports for the proton exchange membrane (PEM water electrolyzers using IrO2 nanoparticles as oxygen evolution electrocatalyst. Here, the performance of IrO2 nanoparticles formed and deposited in situ onto carbon nitride support for PEM water electrolysis was explored based on previous preliminary studies conducted in related systems. The results revealed that this preparation route catalyzed the decomposition of the carbon nitride to form a material with much lower N content. This resulted in a significant enhancement of the performance of the gCNH-IrO2 (or N-doped C-IrO2 electrocatalyst that was likely attributed to higher electrical conductivity of the N-doped carbon support.

  11. Effect of Strongly Alkaline Electrolyzed Water on Silk Degumming and the Physical Properties of the Fibroin Fiber.

    Directory of Open Access Journals (Sweden)

    Ting-Ting Cao

    Full Text Available Strongly alkaline electrolyzed water (SAEW was prepared by electrolysis of tap water in a laboratory-made water electrolyzer. The pH of stored SAEW was stable for more than one month. The hardness of the electrolyzed water was 30% lower and the Na(+ concentration was 18% higher than those of the tap water. Silkworm cocoon shells were boiled in pH 11.50 SAEW at a ratio of 1∶40∼80 (W/V for 20 min and the sericin layers around the silk fibroin fibers were removed completely. The tensile properties and thermal decomposition temperature of a single filament of silk fibroin obtained by the SAEW method were almost the same as those for the fiber obtained by the neutral soap, and much higher than those for the fiber obtained by Na2CO3 degumming. The results demonstrate that SAEW is an environmentally friendly and pollution-free silk degumming agent that allows highly efficient, low cost recovery of sericin.

  12. Application of slightly acidic electrolyzed water for inactivating microbes in a layer breeding house.

    Science.gov (United States)

    Hao, X X; Li, B M; Wang, C Y; Zhang, Q; Cao, W

    2013-10-01

    Lots of microorganisms exist in layer houses can cause bird diseases and worker health concerns. Spraying chemical disinfectants is an effective way to decontaminate pathogenic microorganisms in the air and on surfaces in poultry houses. Slightly acidic electrolyzed water (SAEW, pH 5.0-6.5) is an ideal, environmentally friendly broad-spectrum disinfectant to prevent and control bacterial or viral infection in layer farms. The purpose of this work was to investigate the cleaning effectiveness of SAEW for inactivating the microbes in layer houses. The effect of SAEW was evaluated by solid materials and surface disinfection in a hen house. Results indicate that SAEW with an available chlorine concentration of 250 mg/L, pH value of 6.19, and oxygen reduction potential of 974 mV inactivated 100% of bacteria and fungi in solid materials (dusts, feces, feather, and feed), which is more efficient than common chemical disinfectant such as benzalkonium chloride solution (1:1,000 vol/vol) and povidone-iodine solution (1:1,000 vol/vol). Also, it significantly reduced the microbes on the equipment or facility surfaces (P < 0.05), including floor, wall, feed trough, and water pipe surfaces. Moreover, SAEW effectively decreased the survival rates of Salmonella and Escherichia coli by 21 and 16 percentage points. In addition, spraying the target with tap water before disinfection plays an important role in spray disinfection.

  13. Control of spoiler Pseudomonas spp. on fresh cut vegetables by neutral electrolyzed water.

    Science.gov (United States)

    Pinto, Loris; Ippolito, Antonio; Baruzzi, Federico

    2015-09-01

    In the present study, we evaluated the antimicrobial activity of neutral electrolyzed water (NEW) against 14 strains of spoilage Pseudomonas of fresh cut vegetables under cold storage. The NEW, produced from solutions of potassium and sodium chloride, and sodium bicarbonate developed up to 4000 mg/L of free chlorine, depending on the salt and relative concentration used. The antimicrobial effect of the NEW was evaluated against different bacterial strains at 10(5) cells/ml, with different combinations of free chlorine concentration/contact time; all concentrations above 100 mg/L, regardless of the salt used, were found to be bactericidal already after 2 min. When catalogna chicory and lettuce leaves were dipped for 5 min in diluted NEW, microbial loads of mesophilic bacteria and Enterobacteriaceae were reduced on average of 1.7 log cfu/g. In addition, when lettuce leaves were dipped in a cellular suspension of the spoiler Pseudomonas chicorii I3C strain, diluted NEW was able to reduce Pseudomonas population of about 1.0 log cfu/g. Thanks to its high antimicrobial activity against spoilage microorganisms, and low cost of operation, the application of cycles of electrolysis to the washing water looks as an effective tool in controlling fresh cut vegetable microbial spoilage contamination occurring during washing steps. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Suitability of electrolyzed oxidizing water for the disinfection of hard surfaces and equipment in radiology.

    Science.gov (United States)

    Pintaric, Robert; Matela, Joze; Pintaric, Stefan

    2015-01-01

    Hospitals are faced with increasingly resistant strains of micro-organisms. When it comes to disinfection, individual parts of electronic equipment of angiology diagnostics such as patient couches of computer tomography (CT) and magnetic resonance imaging (MRI) scanners prove to be very hard to disinfect. Disinfectants of choice are therefore expected to possess properties such as rapid, residue-free action without any damaging effect on the sensitive electronic equipment. This paper discusses the use of the neutral electrolyzed oxidizing water (EOW) as a biocide for the disinfection of diagnostic rooms and equipment. The CT and MRI rooms were aerosolized with EOW using aerosolization device. The presence of micro-organisms before and after the aerosolization was recorded with the help of sedimentation and cyclone air sampling. Total body count (TBC) was evaluated in absolute and log values. The number of micro-organisms in hospital rooms was low as expected. Nevertheless, a possible TBC reduction between 78.99-92.50% or 50.50-70.60% in log values was recorded. The research has shown that the use of EOW for the air and hard surface disinfection can considerably reduce the presence of micro-organisms and consequently the possibility of hospital infections. It has also demonstrated that the sedimentation procedure is insufficient for the TBC determination. The use of Biocide aerosolization proved to be efficient and safe in all applied ways. Also, no eventual damage to exposed devices or staff was recorded.

  15. Development of Portable Flow-Through Electrochemical Sanitizing Unit to Generate Near Neutral Electrolyzed Water.

    Science.gov (United States)

    Zhang, Jufang; Yang, Hongshun; Chan, Joel Zhi Yang

    2018-03-01

    We developed a portable flow-through, electrochemical sanitizing unit to produce near neutral pH electrolyzed water (producing NEW). Two methods of redirecting cathode yields back to the anode chamber and redirecting anode yields the cathode chamber were used. The NEW yields were evaluated, including: free available chlorine (FAC), oxidation-reduction potential (ORP), and pH. The performances of 2 electrodes (RuO 2 -IrO 2 /TiO 2 and IrO 2 -Ta 2 O 5 /TiO 2 ) were investigated. The unit produced NEW at pH 6.46 to 7.17, an ORP of 805.5 to 895.8 mV, and FAC of 3.7 to 82.0 mg/L. The NEW produced by redirecting cathode yields had stronger bactericidal effects than the NEW produced by redirecting anode yields or NEW produced by mixing the commercial unit's anode and cathode product (P portable flow-through, NEW-producing unit has great potential in a wide range of applications, such as organic farm, households, and small food industries. The examined sanitizing treatments showed effective control of Escherichia coli O157:H7 and Listeria monocytogenes. © 2018 Institute of Food Technologists®.

  16. The use of ultrasound and slightly acidic electrolyzed water as alternative technologies in the meat industry

    Directory of Open Access Journals (Sweden)

    Flores, D. R. M.,

    2017-06-01

    Full Text Available The quality of meat from different animal species is defined by chemical, physical sensory and microbiological characteristics, which can be influenced by procedures during the slaughter of animals. Technologies such as ultrasound (US and slightly acidic electrolyzed water (SAEW are being studied in order to assist in food processing and in developing methods that are economically viable and environmentally sustainable. The aim of this paper is to discuss the relationship between US and SAEW in relation to tenderness, microbiology, and oxidation of meat. The meat industry was a pioneer in the use of the ultrasound, which initially aimed to determine the layer of fat on carcasses and subsequently improve the tenderness of the meat. Recently studies mention that the ultrasound and SAEW can influence the microbiological parameters. The combination of both technologies should also be considered, with the possibility of enhancing the antimicrobial effects. However, there is little information regarding oxidative parameters promoted in meat for these two alternative technologies, where the individual or when interspersed use. Knowing the actions and consequences of ultrasound and SAEW in meat will enable the opening of new perspectives about the application of these technologies in the meat industry.

  17. Efficacy of sanitized ice in reducing bacterial load on fish fillet and in the water collected from the melted ice.

    Science.gov (United States)

    Feliciano, Lizanel; Lee, Jaesung; Lopes, John A; Pascall, Melvin A

    2010-05-01

    This study investigated the efficacy of sanitized ice for the reduction of bacteria in the water collected from the ice that melted during storage of whole and filleted Tilapia fish. Also, bacterial reductions on the fish fillets were investigated. The sanitized ice was prepared by freezing solutions of PRO-SAN (an organic acid formulation) and neutral electrolyzed water (NEW). For the whole fish study, the survival of the natural microflora was determined from the water of the melted ice prepared with PRO-SAN and tap water. These water samples were collected during an 8 h storage period. For the fish fillet study, samples were inoculated with Escherichia coli K12, Listeria innocua, and Pseudomonas putida then stored on crushed sanitized ice. The efficacies of these were tested by enumerating each bacterial species on the fish fillet and in the water samples at 12 and 24 h intervals for 72 h, respectively. Results showed that each bacterial population was reduced during the test. However, a bacterial reduction of fillet samples. A maximum of approximately 2 log CFU and > 3 log CFU reductions were obtained in the waters sampled after the storage of whole fish and the fillets, respectively. These reductions were significantly (P < 0.05) higher in the water from sanitized ice when compared with the water from the unsanitized melted ice. These results showed that the organic acid formulation and NEW considerably reduced the bacterial numbers in the melted ice and thus reduced the potential for cross-contamination.

  18. Effectiveness of Neutral Electrolyzed Water on Incidence of Fungal Rot on Tomato Fruits ( Solanum lycopersicum L.).

    Science.gov (United States)

    Vásquez-López, Alfonso; Villarreal-Barajas, Tania; Rodríguez-Ortiz, Gerardo

    2016-10-01

    We assessed the effect of neutral electrolyzed water (NEW) on the incidence of rot on tomato ( Solanum lycopersicum L.) fruits inoculated with Fusarium oxysporum , Galactomyces geotrichum , and Alternaria sp. at sites with lesions. The inoculated fruits were treated with NEW at 10, 30, and 60 mg liter -1 active chlorine, with copper oxychloride fungicide, and with sterile distilled water (control) for 3, 5, and 10 min. In the experiment with F. oxysporum , 50 to 80% of the control fruits and 50 to 60% of the fruits treated with the fungicide exhibited symptoms of rot at the inoculated sites. The lowest incidence recorded was 30% for fruits treated with NEW at 60 mg liter -1 active chlorine with an immersion time of 5 min. In the experiment with G. geotrichum , incidence of rot on control fruits was 70 to 90%, and for treatment with fungicide rot incidence was 50 to 90%. NEW at 60 mg liter -1 active chlorine significantly reduced incidence of symptomatic fruit: only 30% of the inoculated fruits washed for 5 min had damage from rot. In the experiment with Alternaria sp., 60 to 90% of the fruits in the control group and 60 to 70% of the fruits in the fungicide group were symptomatic. The lowest incidence was recorded for the treatment in which the fruits were submerged in NEW with 60 mg liter -1 active chlorine for 3 min. In this group, 40 to 50% of the fruits exhibited symptoms of rot. These results were obtained 8 days after inoculation. NEW, with 60 mg liter -1 active chlorine, significantly reduced incidence of rot symptoms on fruits inoculated with one of the experimental fungi relative to the control (P ≤ 0.05). NEW at 60 mg liter -1 is effective in the control of fungal rot in tomatoes.

  19. Presence of hydrogen peroxide, a source of hydroxyl radicals, in acid electrolyzed water.

    Directory of Open Access Journals (Sweden)

    Takayuki Mokudai

    Full Text Available BACKGROUND: Acid electrolyzed water (AEW, which is produced through the electrolysis of dilute sodium chloride (NaCl or potassium chloride solution, is used as a disinfectant in various fields because of its potent antimicrobial activity. The hydroxyl radical, an oxygen radical species, is often suggested as a putative active ingredient for AEW antimicrobial activity. METHODOLOGY/PRINCIPAL FINDINGS: The aim of the present study is to detect hydroxyl radicals in AEW. The hydroxyl radicals in AEW prepared under different conditions were determined using an electron spin resonance (ESR technique. A signal from 5,5-dimethyl-1-pyrroline N-oxide (DMPO-OH, an adduct of DMPO and the hydroxyl radical, was detected in AEW prepared by double or triple electrolyses of 1% NaCl but not of 0.1% NaCl solution. Then the presence of hydrogen peroxide as a proposed source of hydroxyl radicals was examined using a combination of ESR and a Fenton reaction. The DMPO-OH signal was clearly detected, even in AEW prepared by single electrolysis of 0.1% NaCl solution, when ferrous sulfate was added to induce a Fenton reaction, indicating the presence of hydrogen peroxide in the AEW. Since sodium formate, a hydroxyl radical scavenger, did not affect the bactericidal activity of AEW, it is concluded that the radical is unlikely to contribute to the antimicrobial activity of AEW, although a small amount of the radical is produced from hydrogen peroxide. Dimethyl sulfoxide, the other hydroxyl radical scavenger used in the present study, canceled the bactericidal activity of AEW, accompanied by complete depletion of free available chlorine, suggesting that hypochlorous acid is probably a major contributor to the antimicrobial activity. CONCLUSIONS: It is strongly suggested that although hydrogen peroxide is present in AEW as a source of hydroxyl radicals, the antimicrobial activity of AEW does not depend on these radicals.

  20. Electrochemical performance of Ni/TiO{sub 2} hollow sphere in proton exchange membrane water electrolyzers system

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, Jayeeta; Srivastava, Rohit; Srivastava, Prem Kumar [Birla Institute of Technology, Jharkhand (India)

    2013-08-15

    This work presents the electrocatalytic evaluation of Ni/TiO{sub 2} hollow sphere materials in PEM water electrolysis cell. All the electrocatalysts have shown remarkably enhanced electrocatalytic properties in comparison with their performance in aqueous electrolysis cell. According to cyclic voltammetric results, 0.36 A cm{sup −2} peak current density has been exhibited in hydrogen evolution reaction (HER) from 30 wt% Ni/TiO{sub 2} electrocatalyst. 15 wt% Ni-doped titania sample has shown the best result in oxygen evolution reaction (OER) with the anodic peak current density of 0.3 A cm{sup −2}. In the anodic polarization curves, the performance of 15 wt% Ni/TiO{sub 2} hollow sphere electrocatalyst was evaluated up to 140 mA cm{sup −2} at comparatively lower over-potential value. 20 wt% Ni/TiO{sub 2} hollow sphere electrocatalyst has also shown electrochemical stability in PEM water electrolyzer for 48 h long analysis. The comparative electrocatalytic behavior of hollow spherical materials with non-sphericals is also presented, which clearly shows the influence of hollow spherical structure in greater electrocatalytic activity of the materials. The physical characterization of all the hollow spherical materials is presented in this work, which has confirmed their better electrochemical behavior in PEM water electrolyzer.

  1. Electrochemical performance of Ni/TiO_2 hollow sphere in proton exchange membrane water electrolyzers system

    International Nuclear Information System (INIS)

    Chattopadhyay, Jayeeta; Srivastava, Rohit; Srivastava, Prem Kumar

    2013-01-01

    This work presents the electrocatalytic evaluation of Ni/TiO_2 hollow sphere materials in PEM water electrolysis cell. All the electrocatalysts have shown remarkably enhanced electrocatalytic properties in comparison with their performance in aqueous electrolysis cell. According to cyclic voltammetric results, 0.36 A cm"−"2 peak current density has been exhibited in hydrogen evolution reaction (HER) from 30 wt% Ni/TiO_2 electrocatalyst. 15 wt% Ni-doped titania sample has shown the best result in oxygen evolution reaction (OER) with the anodic peak current density of 0.3 A cm"−"2. In the anodic polarization curves, the performance of 15 wt% Ni/TiO_2 hollow sphere electrocatalyst was evaluated up to 140 mA cm"−"2 at comparatively lower over-potential value. 20 wt% Ni/TiO_2 hollow sphere electrocatalyst has also shown electrochemical stability in PEM water electrolyzer for 48 h long analysis. The comparative electrocatalytic behavior of hollow spherical materials with non-sphericals is also presented, which clearly shows the influence of hollow spherical structure in greater electrocatalytic activity of the materials. The physical characterization of all the hollow spherical materials is presented in this work, which has confirmed their better electrochemical behavior in PEM water electrolyzer

  2. The application of alkaline and acidic electrolyzed water in the sterilization of chicken breasts and beef liver.

    Science.gov (United States)

    Shimamura, Yuko; Shinke, Momoka; Hiraishi, Miki; Tsuchiya, Yusuke; Masuda, Shuichi

    2016-05-01

    The sterilization effect of a combination treatment with alkaline electrolyzed water (AlEW) and strong acidic electrolyzed water (StAEW) on fresh chicken breasts and beef liver was evaluated. Samples (1, 5, and 10 g) were inoculated with Salmonella Enteritidis NBRC3313, Escherichia coli ATCC 10798, Staphylococcus aureus FDA209P, and S. aureus C-29 [staphylococcal enterotoxin A (SEA) productive strain] and subjected to a dipping combination treatment (4°C and 25°C for 3 min) with AlEW and StAEW. Combination treatment with AlEW and StAEW significantly reduced the bacteria, and reduction of more than 1 log colony-forming units (CFU)/g was achieved. Furthermore, this combination treatment significantly decreased the SEA gene expression level in samples. Some quality variables of the meat samples such as pH, lipid oxidation, color, amino-acid content, texture, and sensory characteristics showed no significant differences between the combination treatment with AlEW and StAEW and the untreated control.

  3. Viability of sublethally injured coliform bacteria on fresh-cut cabbage stored in high CO2 atmospheres following rinsing with electrolyzed water.

    Science.gov (United States)

    Izumi, Hidemi; Inoue, Ayano

    2018-02-02

    The extent of sublethally injured coliform bacteria on shredded cabbage, either rinsed or not rinsed with electrolyzed water, was evaluated during storage in air and high CO 2 controlled atmospheres (5%, 10%, and 15%) at 5°C and 10°C using the thin agar layer (TAL) method. Sublethally injured coliform bacteria on nonrinsed shredded cabbage were either absent or they were injured at a 64-65% level when present. Rinsing of shredded cabbage with electrolyzed water containing 25ppm available chlorine reduced the coliform counts by 0.4 to 1.1 log and caused sublethal injury ranging from 42 to 77%. Pantoea ananatis was one of the species injured by chlorine stress. When shredded cabbage, nonrinsed or rinsed with electrolyzed water, was stored in air and high CO 2 atmospheres at 5°C for 7days and 10°C for 5days, coliform counts on TAL plates increased from 3.3-4.5 to 6.5-9.0 log CFU/g during storage, with the increase being greater at 10°C than at 5°C. High CO 2 of 10% and 15% reduced the bacterial growth on shredded cabbage during storage at 5°C. Although injured coliform bacteria were not found on nonrinsed shredded cabbage on the initial day, injured coliforms at a range of 49-84% were detected on samples stored in air and high CO 2 atmospheres at 5°C and 10°C. Injured cells were detected more frequently during storage at both temperatures irrespective of the CO 2 atmosphere when shredded cabbage was rinsed with electrolyzed water. These results indicated that injured coliform bacteria on shredded cabbage, either rinsed or not rinsed with electrolyzed water, exhibited different degrees of injury during storage regardless of the CO 2 atmosphere and temperature tested. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Fully printed and integrated electrolyzer cells with additive manufacturing for high-efficiency water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Gaoqiang; Mo, Jingke; Kang, Zhenye; Dohrmann, Yeshi; List, Frederick A.; Green, Johney B.; Babu, Sudarsanam S.; Zhang, Feng-Yuan

    2018-04-01

    Using additive manufacturing (AM) technology, a fundamental material and structure innovation was proposed to significantly increase the energy efficiency, and to reduce the weight, volume and component quantity of proton exchange membrane electrolyzer cells (PEMECs). Four conventional parts (liquid/gas diffusion layer, bipolar plate, gasket, and current distributor) in a PEMEC were integrated into one multifunctional AM plate without committing to tools or molds for the first time. In addition, since the interfacial contact resistances between those parts were eliminated, the comprehensive in-situ characterizations of AM cells showed that an excellent energy efficiency of up to 86.48% was achieved at 2 A/cm2 and 80 degrees C, and the hydrogen generation rate was increased by 61.81% compared to the conventional cell. More importantly, the highly complex inner structures of the AM integrated multifunctional plates also exhibit the potential to break limitations of conventional manufacture methods for hydrogen generation and to open a door for the development of other energy conversion devices, including fuel cells, solar cells and batteries.

  5. Operation method study based on the energy balance of an independent microgrid using solar-powered water electrolyzer and an electric heat pump

    International Nuclear Information System (INIS)

    Obara, Shin'ya; Watanabe, Seizi; Rengarajan, Balaji

    2011-01-01

    A completely energy-independent microgrid (green microgrid) was examined in this work with the aims of abating greenhouse gas emissions by spreading the use of green energy, providing energy backup systems for disaster, and increasing the energy utilization efficiency with the use of exhaust heat. This paper analyzed the energy supply to six houses in a cold region. The green microgrid consisted of photovoltaics, water electrolyzers, proton-exchange membrane fuel cells (PEFCs), and heat pumps. To investigate the operation method and the capacity of each piece of equipment in the arrangement, a distributed system with two or more sets of equipment and a central system with one set of equipment were analyzed by a genetic algorithm. By introducing the prior energy need pattern of a cold region into the proposed system, the operation method and equipment capacity based on the power and heat balance were clarified. By introducing the partial load performance of a water electrolyzer and a PEFC into the analysis program, the operation method of each system was investigated. It was found that the area of a solar cell of a distributed system could be reduced by 12% as compared to a central system. -- Highlights: → A completely energy-independent microgrid (green microgrid) was planned. → The green microgrid consisted of photovoltaics, water electrolyzers, PEM-FCs, and heat pumps. → Operation of a concentrated system and a distributed system. → Investigate of the operation method and the capacity of each piece of equipment.

  6. Acidic electrolyzed water as a novel transmitting medium for high hydrostatic pressure reduction of bacterial loads on shelled fresh shrimp

    Directory of Open Access Journals (Sweden)

    Suping eDu

    2016-03-01

    Full Text Available Acidic electrolyzed water (AEW, a novel non-thermal sterilization technology, is widely used in the food industry. In this study, we firstly investigated the effect of AEW as a new pressure transmitting medium for high hydrostatic pressure (AEW-HHP processing on microorganisms inactivation on shelled fresh shrimp. The optimal conditions of AEW-HHP for Vibrio parahaemolyticus inactivation on sterile shelled fresh shrimp were obtained using response surface methodology: NaCl concentration to electrolysis 1.5 g/L, treatment pressure 400 MPa, treatment time 10 min. Under the optimal conditions mentioned above, AEW dramatically enhanced the efficiency of HHP for inactivating V. parahaemolyticus and Listeria monocytogenes on artificially contaminated shelled fresh shrimp, and the log reductions were up to 6.08 and 5.71 log10 CFU/g respectively, while the common HHP could only inactivate the two pathogens up to 4.74 and 4.31 log10 CFU/g respectively. Meanwhile, scanning electron microscopy (SEM showed the same phenomenon. For the naturally contaminated shelled fresh shrimp, AEW-HHP could also significantly reduce the micro flora when examined using plate count and PCR-DGGE. There were also no significant changes, histologically, in the muscle tissues of shrimps undergoing the AEW-HHP treatment. In summary, using AEW as a new transmitting medium for HHP processing is an innovative non thermal technology for improving the food safety of shrimp and other aquatic products.

  7. Acidic Electrolyzed Water as a Novel Transmitting Medium for High Hydrostatic Pressure Reduction of Bacterial Loads on Shelled Fresh Shrimp

    Science.gov (United States)

    Du, Suping; Zhang, Zhaohuan; Xiao, Lili; Lou, Yang; Pan, Yingjie; Zhao, Yong

    2016-01-01

    Acidic electrolyzed water (AEW), a novel non-thermal sterilization technology, is widely used in the food industry. In this study, we firstly investigated the effect of AEW as a new pressure transmitting medium for high hydrostatic pressure (AEW-HHP) processing on microorganisms inactivation on shelled fresh shrimp. The optimal conditions of AEW-HHP for Vibrio parahaemolyticus inactivation on sterile shelled fresh shrimp were obtained using response surface methodology: NaCl concentration to electrolysis 1.5 g/L, treatment pressure 400 MPa, treatment time 10 min. Under the optimal conditions mentioned above, AEW dramatically enhanced the efficiency of HHP for inactivating V. parahaemolyticus and Listeria monocytogenes on artificially contaminated shelled fresh shrimp, and the log reductions were up to 6.08 and 5.71 log10 CFU/g respectively, while the common HHP could only inactivate the two pathogens up to 4.74 and 4.31 log10 CFU/g respectively. Meanwhile, scanning electron microscopy (SEM) showed the same phenomenon. For the naturally contaminated shelled fresh shrimp, AEW-HHP could also significantly reduce the micro flora when examined using plate count and PCR-DGGE. There were also no significant changes, histologically, in the muscle tissues of shrimps undergoing the AEW-HHP treatment. In summary, using AEW as a new transmitting medium for HHP processing is an innovative non thermal technology for improving the food safety of shrimp and other aquatic products. PMID:27014228

  8. 21 CFR 135.160 - Water ices.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Water ices. 135.160 Section 135.160 Food and Drugs... CONSUMPTION FROZEN DESSERTS Requirements for Specific Standardized Frozen Desserts § 135.160 Water ices. (a) Description. Water ices are the foods each of which is prepared from the same ingredients and in the same...

  9. Ameliorative Effects of Neutral Electrolyzed Water on Growth Performance, Biochemical Constituents, and Histopathological Changes in Turkey Poults during Aflatoxicosis

    Directory of Open Access Journals (Sweden)

    Denise Gómez-Espinosa

    2017-03-01

    Full Text Available Different in vitro and in silico approaches from our research group have demonstrated that neutral electrolyzed water (NEW can be used to detoxify aflatoxins. The objective of this investigation was to evaluate the ability of NEW to detoxify B-aflatoxins (AFB1 and AFB2 in contaminated maize and to confirm detoxification in an in vivo experimental model. Batches of aflatoxin-contaminated maize were detoxified with NEW and mixed in commercial feed. A total of 240 6-day-old female large white Nicholas-700 turkey poults were randomly divided into four treatments of six replicates each (10 turkeys per replicate, which were fed ad libitum for two weeks with the following dietary treatments: (1 control feed containing aflatoxin-free maize (CONTROL; (2 feed containing the aflatoxin-contaminated maize (AF; (3 feed containing the aflatoxin-contaminated maize detoxified with NEW (AF + NEW; and (4 control feed containing aflatoxin-free maize treated with NEW (NEW. Compared to the control groups, turkey poults of the AF group significantly reduced body weight gain and increased feed conversion ratio and mortality rate; whereas turkey poults of the AF + NEW group did not present significant differences on productive parameters. In addition, alterations in serum biochemical constituents, enzyme activities, relative organ weight, gross morphological changes and histopathological studies were significantly mitigated by the aflatoxin-detoxification procedure. From these results, it is concluded that the treatment of aflatoxin-contaminated maize with NEW provided reasonable protection against the effects caused by aflatoxins in young turkey poults.

  10. Combination treatment of alkaline electrolyzed water and citric acid with mild heat to ensure microbial safety, shelf-life and sensory quality of shredded carrots.

    Science.gov (United States)

    Rahman, S M E; Jin, Yong-Guo; Oh, Deog-Hwan

    2011-05-01

    The objective of this study was to determine the synergistic effect of alkaline electrolyzed water and citric acid with mild heat against background and pathogenic microorganisms on carrots. Shredded carrots were inoculated with approximately 6-7 log CFU/g of Escherichia coli O157:H7 (932, and 933) and Listeria monocytogenes (ATCC 19116, and 19111) and then dip treated with alkaline electrolyzed water (AlEW), acidic electrolyzed water (AcEW), 100 ppm sodium hypochlorite (NaOCl), deionized water (DaIW), or 1% citric acid (CA) alone or with combinations of AlEW and 1% CA (AlEW + CA). The populations of spoilage bacteria on the carrots were investigated after various exposure times (1, 3, and 5 min) and treatment at different dipping temperatures (1, 20, 40, and 50 °C) and then optimal condition (3 min at 50 °C) was applied against foodborne pathogens on the carrots. When compared to the untreated control, treatment AcEW most effectively reduced the numbers of total bacteria, yeast and fungi, followed by AlEW and 100 ppm NaOCl. Exposure to all treatments for 3 min significantly reduced the numbers of total bacteria, yeast and fungi on the carrots. As the dipping temperature increased from 1 °C to 50 °C, the reductions of total bacteria, yeast and fungi increased significantly from 0.22 to 2.67 log CFU/g during the wash treatment (p ≤ 0.05). The combined 1% citric acid and AlEW treatment at 50 °C showed a reduction of the total bacterial count and the yeast and fungi of around 3.7 log CFU/g, as well as effective reduction of L. monocytogenes (3.97 log CFU/g), and E. Coli O157:H7 (4 log CFU/g). Combinations of alkaline electrolyzed water and citric acid better maintained the sensory and microbial quality of the fresh-cut carrots and enhanced the overall shelf-life of the produce. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Inactivation of E. coli O157:H7 on blueberries by electrolyzed water, ultraviolet light, and ozone.

    Science.gov (United States)

    Kim, Chyer; Hung, Yen-Con

    2012-04-01

    Increased interest in blueberries due to their nutritional and health benefits has led to an increase in consumption. However, blueberries are consumed mostly raw or minimally processed and are susceptible to microbial contamination like other type of fresh produce. This study was, therefore, undertaken to evaluate the efficacy of electrostatic spray of electrolyzed oxidizing (EO) water, UV light, ozone, and a combination of ozone and UV light in killing Escherichia coli O157:H7 on blueberries. A 5-strain mixture of E. coli O157:H7 were inoculated on the calyx and skin of blueberries and then subjected to the treatments. Electrostatic EO water spray reduced initial populations of E. coli O157:H7 by only 0.13 to 0.24 log CFU/g and 0.88 to 1.10 log CFU/g on calyx and skin of blueberries, respectively. Ozone treatment with 4000 mg/L reduced E. coli O157:H7 by only 0.66 and 0.72 log CFU/g on calyx and skin of blueberries, respectively. UV light at 20 mW/cm² for 10 min was the most promising single technology and achieved 2.14 and greater than 4.05 log reductions of E. coli O157:H7 on the calyx and skin of blueberries, respectively. The combination treatment of 1 min ozone and followed by a 2 min UV achieved more than 1 and 2 log additional reductions on blueberry calyx than UV or ozone alone, respectively. Outbreaks of foodborne illnesses have been associated with consumption of fresh produce. Many methods for removing pathogens as well as minimizing their effect on quality of treated produce have been investigated. UV technology and its combination with ozone used in this study to inactive E. coli O157:H7 on blueberries was found effective. Results from this study may help producers and processors in developing hurdle technologies for the delivery of safer blueberries to consumers. © 2012 Institute of Food Technologists®

  12. Experimental provocation of 'ice-cream headache' by ice cubes and ice water.

    Science.gov (United States)

    Mages, Stephan; Hensel, Ole; Zierz, Antonia Maria; Kraya, Torsten; Zierz, Stephan

    2017-04-01

    Background There are various studies on experimentally provoked 'ice-cream headache' or 'headache attributed to ingestion or inhalation of a cold stimulus' (HICS) using different provocation protocols. The aim of this study was to compare two provocation protocols. Methods Ice cubes pressed to the palate and fast ingestion of ice water were used to provoke HICS and clinical features were compared. Results The ice-water stimulus provoked HICS significantly more often than the ice-cube stimulus (9/77 vs. 39/77). Ice-water-provoked HICS had a significantly shorter latency (median 15 s, range 4-97 s vs. median 68 s, range 27-96 s). There was no difference in pain localisation. Character after ice-cube stimulation was predominantly described as pressing and after ice-water stimulation as stabbing. A second HICS followed in 10/39 (26%) of the headaches provoked by ice water. Lacrimation occurred significantly more often in volunteers with than in those without HICS. Discussion HICS provoked by ice water was more frequent, had a shorter latency, different pain character and higher pain intensity than HICS provoked by ice cubes. The finding of two subsequent HICS attacks in the same volunteers supports the notion that two types of HICS exist. Lacrimation during HICS indicates involvement of the trigeminal-autonomic reflex.

  13. Physico-Chemical, Biological and Therapeutic Characteristics of Electrolyzed Reduced Alkaline Water (ERAW

    Directory of Open Access Journals (Sweden)

    Marc Henry

    2013-12-01

    Full Text Available The consumption of alkaline reduced water produced by domestic electrolysis devices was approved in Japan in 1965 by the Ministry of Health, Labour and Welfare for the cure of gastro-intestinal disorders. Today, these devices are freely available in several countries and can be easily purchased without reserve. The commercial information included with the device recommends the consumption of 1–1.5 L of water per day, not only for gastro-intestinal disorders but also for numerous other illnesses such as diabetes, cancer, inflammation, etc. Academic research in Japan on this subject has been undergoing since 1990 only but has established that the active ingredient is dissolved dihydrogen that eliminates the free radical HO• in vivo. In addition, it was demonstrated that degradation of the electrodes during functioning of the device releases very reactive nanoparticles of platinum, the toxicity of which has not yet been clearly proven. This report recommends alerting health authorities of the uncontrolled availability of these devices used as health products, but which generate drug substances and should therefore be sold according to regulatory requirements.

  14. Efficacy of chlorine, acidic electrolyzed water and aqueous chlorine dioxide solutions to decontaminate Escherichia coli O157:H7 from lettuce leaves.

    Science.gov (United States)

    Keskinen, Lindsey A; Burke, Angela; Annous, Bassam A

    2009-06-30

    This study compared the efficacy of chlorine (20-200 ppm), acidic electrolyzed water (50 ppm chlorine, pH 2.6), acidified sodium chlorite (20-200 ppm chlorite ion concentration, Sanova), and aqueous chlorine dioxide (20-200 ppm chlorite ion concentration, TriNova) washes in reducing populations of Escherichia coli O157:H7 on artificially inoculated lettuce. Fresh-cut leaves of Romaine or Iceberg lettuce were inoculated by immersion in water containing E. coli O157:H7 (8 log CFU/ml) for 5 min and dried in a salad spinner. Leaves (25 g) were then washed for 2 min, immediately or following 24 h of storage at 4 degrees C. The washing treatments containing chlorite ion concentrations of 100 and 200 ppm were the most effective against E. coli O157:H7 populations on Iceberg lettuce, with log reductions as high as 1.25 log CFU/g and 1.05 log CFU/g for TriNova and Sanova wash treatments, respectively. All other wash treatments resulted in population reductions of less than 1 log CFU/g. Chlorine (200 ppm), TriNova, Sanova, and acidic electrolyzed water were all equally effective against E. coli O157:H7 on Romaine, with log reductions of approximately 1 log CFU/g. The 20 ppm chlorine wash was as effective as the deionized water wash in reducing populations of E. coli O157:H7 on Romaine and Iceberg lettuce. Scanning electron microscopy indicated that E. coli O157:H7 that was incorporated into biofilms or located in damage lettuce tissue remained on the lettuce leaf, while individual cells on undamaged leaf surfaces were more likely to be washed away.

  15. Viscosity of interfacial water regulates ice nucleation

    International Nuclear Information System (INIS)

    Li, Kaiyong; Chen, Jing; Zhang, Qiaolan; Zhang, Yifan; Xu, Shun; Zhou, Xin; Cui, Dapeng; Wang, Jianjun; Song, Yanlin

    2014-01-01

    Ice formation on solid surfaces is an important phenomenon in many fields, such as cloud formation and atmospheric icing, and a key factor for applications in preventing freezing. Here, we report temperature-dependent nucleation rates of ice for hydrophilic and hydrophobic surfaces. The results show that hydrophilic surface presents a lower ice nucleation rate. We develop a strategy to extract the thermodynamic parameters, J 0 and Γ, in the context of classical nucleation theory. From the extracted J 0 and Γ, we reveal the dominant role played by interfacial water. The results provide an insight into freezing mechanism on solid surfaces

  16. Advanced Oxygen Evolution Catalysts for PEM Electrolyzers, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Future NASA missions require high efficiency, lightweight, long life, and maintenance-free water electrolyzer technologies to generate oxygen and/or hydrogen for...

  17. Electrolyzer for NASA Lunar Regenerative Fuel Cells, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Water electrolyzer stacks are a key component of regenerative fuel cells, designed to replace batteries as a means of storing electric energy on the lunar surface....

  18. Escherichia coli and Cronobacter sakazakii in 'Tommy Atkins' minimally processed mangos: Survival, growth and effect of UV-C and electrolyzed water.

    Science.gov (United States)

    Santo, David; Graça, Ana; Nunes, Carla; Quintas, Célia

    2018-04-01

    These studies were aimed at assessing the growing capacity of Escherichia coli and Cronobacter sakazakii and the effectiveness of Ultraviolet-C (UV-C) radiation, acidic electrolyzed (AEW) and neutral electrolyzed (NEW) waters in the inhibition of these bacteria on minimally processed 'Tommy Atkins' mangoes (MPM). The fruits were contaminated by dip inoculation and kept 10 days at 4, 8, 12 and 20 °C while enumerating bacteria. Contaminated mangoes were disinfected using UV-C (2.5, 5, 7.5 and 10 kJ/m 2 ), AEW, NEW and sodium hypochlorite (SH) and the microorganisms were monitored. None of the enterobacteria grew at 4, 8 and 12 °C regardless of having persisted during the 10-day period. At 20 °C, E. coli and C. sakazakii grew, after adaption phases of 48 h and 24 h, to values of 8.7 and 8.5 log cfu/g at day eight, respectively. E. coli showed the highest reduction counts on the MPM washed with NEW and SH (2.2 log cfu/g). UV-C was more effective in reducing C. sakazakii (2.4-2.6 log cfu/g), when compared to AEW, NEW and SH (1.2-1.8 log cfu/g). The efficacy of decontamination technologies depends on microorganisms, highlighting the importance of preventing contamination at the primary production and of combining different methods to increase the safety of fresh-cut fruits. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. New Approach in Translational Medicine: Effects of Electrolyzed Reduced Water (ERW on NF-κB/iNOS Pathway in U937 Cell Line under Altered Redox State

    Directory of Open Access Journals (Sweden)

    Sara Franceschelli

    2016-09-01

    Full Text Available It is known that increased levels of reactive oxygen species (ROS and reactive nitrogen species (RNS can exert harmful effects, altering the cellular redox state. Electrolyzed Reduced Water (ERW produced near the cathode during water electrolysis exhibits high pH, high concentration of dissolved hydrogen and an extremely negative redox potential. Several findings indicate that ERW had the ability of a scavenger free radical, which results from hydrogen molecules with a high reducing ability and may participate in the redox regulation of cellular function. We investigated the effect of ERW on H2O2-induced U937 damage by evaluating the modulation of redox cellular state. Western blotting and spectrophotometrical analysis showed that ERW inhibited oxidative stress by restoring the antioxidant capacity of superoxide dismutase, catalase and glutathione peroxidase. Consequently, ERW restores the ability of the glutathione reductase to supply the cell of an important endogenous antioxidant, such as GSH, reversing the inhibitory effect of H2O2 on redox balance of U937 cells. Therefore, this means a reduction of cytotoxicity induced by peroxynitrite via a downregulation of the NF-κB/iNOS pathway and could be used as an antioxidant for preventive and therapeutic application. In conclusion, ERW can protect the cellular redox balance, reducing the risk of several diseases with altered cellular homeostasis such as inflammation.

  20. WATER ICE IN THE KUIPER BELT

    International Nuclear Information System (INIS)

    Brown, M. E.; Fraser, W. C.; Schaller, E. L.

    2012-01-01

    We examine a large collection of low-resolution near-infrared spectra of Kuiper Belt objects (KBOs) and centaurs in an attempt to understand the presence of water ice in the Kuiper Belt. We find that water ice on the surface of these objects occurs in three separate manners: (1) Haumea family members uniquely show surfaces of nearly pure water ice, presumably a consequence of the fragmentation of the icy mantle of a larger differentiated proto-Haumea; (2) large objects with absolute magnitudes of H < 3 (and a limited number to H = 4.5) have surface coverings of water ice—perhaps mixed with ammonia—that appears to be related to possibly ancient cryovolcanism on these large objects; and (3) smaller KBOs and centaurs which are neither Haumea family members nor cold-classical KBOs appear to divide into two families (which we refer to as 'neutral' and 'red'), each of which is a mixture of a common nearly neutral component and either a slightly red or very red component that also includes water ice. A model suggesting that the difference between neutral and red objects due to formation in an early compact solar system either inside or outside, respectively, of the ∼20 AU methanol evaporation line is supported by the observation that methanol is only detected on the reddest objects, which are those which would be expected to have the most of the methanol containing mixture.

  1. The effect of ice-cream-scoop water on the hygiene of ice cream.

    Science.gov (United States)

    Wilson, I. G.; Heaney, J. C.; Weatherup, S. T.

    1997-01-01

    A survey of unopened ice cream, ice cream in use, and ice-cream-scoop water (n = 91) was conducted to determine the effect of scoop water hygiene on the microbiological quality of ice cream. An aerobic plate count around 10(6) c.f.u. ml-1 was the modal value for scoop waters. Unopened ice creams generally had counts around 10(3)-10(4) c.f.u. ml-1 and this increased by one order of magnitude when in use. Many scoop waters had low coliform counts, but almost half contained > 100 c.f.u. ml-1. E. coli was isolated in 18% of ice creams in use, and in 10% of unopened ice creams. S. aureus was not detected in any sample. Statistical analysis showed strong associations between indicator organisms and increased counts in ice cream in use. EC guidelines for indicator organisms in ice cream were exceeded by up to 56% of samples. PMID:9287941

  2. Turbulent heat exchange between water and ice at an evolving ice-water interface

    Science.gov (United States)

    Ramudu, Eshwan; Hirsh, Benjamin Henry; Olson, Peter; Gnanadesikan, Anand

    2016-07-01

    We conduct laboratory experiments on the time evolution of an ice layer cooled from below and subjected to a turbulent shear flow of warm water from above. Our study is motivated by observations of warm water intrusion into the ocean cavity under Antarctic ice shelves, accelerating the melting of their basal surfaces. The strength of the applied turbulent shear flow in our experiments is represented in terms of its Reynolds number $\\textit{Re}$, which is varied over the range $2.0\\times10^3 \\le \\textit{Re} \\le 1.0\\times10^4$. Depending on the water temperature, partial transient melting of the ice occurs at the lower end of this range of $\\textit{Re}$ and complete transient melting of the ice occurs at the higher end. Following these episodes of transient melting, the ice reforms at a rate that is independent of $\\textit{Re}$. We fit our experimental measurements of ice thickness and temperature to a one-dimensional model for the evolution of the ice thickness in which the turbulent heat transfer is parameterized in terms of the friction velocity of the shear flow. The melting mechanism we investigate in our experiments can easily account for the basal melting rate of Pine Island Glacier ice shelf inferred from observations.

  3. Advanced Approaches to Greatly Reduce Hydrogen Gas Crossover Losses in PEM Electrolyzers Operating at High Pressures and Low Current Densities, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — ElectroChem proposes technology advances in its unique PEM IFF water electrolyzer design to meet the NASA requirement for an electrolyzer that will operate very...

  4. Effect of Electrolyzed Water on the Disinfection of Bacillus cereus Biofilms: The Mechanism of Enhanced Resistance of Sessile Cells in the Biofilm Matrix.

    Science.gov (United States)

    Hussain, Mohammad Shakhawat; Kwon, Minyeong; Tango, Charles Nkufi; Oh, Deog Hwan

    2018-05-01

    This study examined the disinfection efficacy and mechanism of electrolyzed water (EW) on Bacillus cereus biofilms. B. cereus strains, ATCC 14579 and Korean Collection for Type Cultures (KCTC) 13153 biofilms, were formed on stainless steel (SS) and plastic slide (PS) coupons. Mature biofilms were treated with slightly acidic EW (SAEW), acidic EW (AEW), and basic EW (BEW). SAEW (available chlorine concentration, 25 ± 1.31 mg L -1 ; pH 5.71 ± 0.16; and oxidation reduction potential, 818 to 855 mV) reduced ATCC 14579 biofilms on plastic slides to below the detection limit within 30 s. However, biofilms on SS coupons showed a higher resistance to the SAEW treatment. When the disinfection activities of three types of EW on biofilms were compared, AEW showed a higher bactericidal activity, followed by SAEW and BEW. In contrast, BEW showed a significantly ( P biofilm dispersal activity than AEW and SAEW. SAEW disinfection of the B. cereus biofilms was due to the disruption of the B. cereus plasma membrane. The higher resistance of biofilms formed on the SS coupon might be due to the higher number of attached cells and extracellular polymeric substances formation that reacts with the active chlorine ions, such as hypochlorous acid and hypochlorite ion of SAEW, which decreased the disinfection efficacy of SAEW. This study showed that the EW treatment effectively disinfected B. cereus biofilms, providing insight into the potential use of EW in the food processing industry to control the biofilm formation of B. cereus.

  5. Control of Listeria innocua Biofilms on Food Contact Surfaces with Slightly Acidic Electrolyzed Water and the Risk of Biofilm Cells Transfer to Duck Meat.

    Science.gov (United States)

    Jeon, Hye Ri; Kwon, Mi Jin; Yoon, Ki Sun

    2018-04-01

    Biofilm formation on food contact surfaces is a potential hazard leading to cross-contamination during food processing. We investigated Listeria innocua biofilm formation on various food contact surfaces and compared the washing effect of slightly acidic electrolyzed water (SAEW) at 30, 50, 70, and 120 ppm with that of 200 ppm of sodium hypochlorite (NaClO) on biofilm cells. The risk of L. innocua biofilm transfer and growth on food at retail markets was also investigated. The viability of biofilms that formed on food contact surfaces and then transferred cells to duck meat was confirmed by fluorescence microscopy. L. innocua biofilm formation was greatest on rubber, followed by polypropylene, glass, and stainless steel. Regardless of sanitizer type, washing removed biofilms from polypropylene and stainless steel better than from rubber and glass. Among the various SAEW concentrations, washing with 70 ppm of SAEW for 5 min significantly reduced L. innocua biofilms on food contact surfaces during food processing. Efficiency of transfer of L. innocua biofilm cells was the highest on polypropylene and lowest on stainless steel. The transferred biofilm cells grew to the maximum population density, and the lag time of transferred biofilm cells was longer than that of planktonic cells. The biofilm cells that transferred to duck meat coexisted with live, injured, and dead cells, which indicates that effective washing is essential to remove biofilm on food contact surfaces during food processing to reduce the risk of foodborne disease outbreaks.

  6. Sensitivity of open-water ice growth and ice concentration evolution in a coupled atmosphere-ocean-sea ice model

    Science.gov (United States)

    Shi, Xiaoxu; Lohmann, Gerrit

    2017-09-01

    A coupled atmosphere-ocean-sea ice model is applied to investigate to what degree the area-thickness distribution of new ice formed in open water affects the ice and ocean properties. Two sensitivity experiments are performed which modify the horizontal-to-vertical aspect ratio of open-water ice growth. The resulting changes in the Arctic sea-ice concentration strongly affect the surface albedo, the ocean heat release to the atmosphere, and the sea-ice production. The changes are further amplified through a positive feedback mechanism among the Arctic sea ice, the Atlantic Meridional Overturning Circulation (AMOC), and the surface air temperature in the Arctic, as the Fram Strait sea ice import influences the freshwater budget in the North Atlantic Ocean. Anomalies in sea-ice transport lead to changes in sea surface properties of the North Atlantic and the strength of AMOC. For the Southern Ocean, the most pronounced change is a warming along the Antarctic Circumpolar Current (ACC), owing to the interhemispheric bipolar seasaw linked to AMOC weakening. Another insight of this study lies on the improvement of our climate model. The ocean component FESOM is a newly developed ocean-sea ice model with an unstructured mesh and multi-resolution. We find that the subpolar sea-ice boundary in the Northern Hemisphere can be improved by tuning the process of open-water ice growth, which strongly influences the sea ice concentration in the marginal ice zone, the North Atlantic circulation, salinity and Arctic sea ice volume. Since the distribution of new ice on open water relies on many uncertain parameters and the knowledge of the detailed processes is currently too crude, it is a challenge to implement the processes realistically into models. Based on our sensitivity experiments, we conclude a pronounced uncertainty related to open-water sea ice growth which could significantly affect the climate system sensitivity.

  7. High Pressure Electrolyzer System Evaluation

    Science.gov (United States)

    Prokopius, Kevin; Coloza, Anthony

    2010-01-01

    This report documents the continuing efforts to evaluate the operational state of a high pressure PEM based electrolyzer located at the NASA Glenn Research Center. This electrolyzer is a prototype system built by General Electric and refurbished by Hamilton Standard (now named Hamilton Sunstrand). It is capable of producing hydrogen and oxygen at an output pressure of 3000 psi. The electrolyzer has been in storage for a number of years. Evaluation and testing was performed to determine the state of the electrolyzer and provide an estimate of the cost for refurbishment. Pressure testing was performed using nitrogen gas through the oxygen ports to ascertain the status of the internal membranes and seals. It was determined that the integrity of the electrolyzer stack was good as there were no appreciable leaks in the membranes or seals within the stack. In addition to the integrity testing, an itemized list and part cost estimate was produced for the components of the electrolyzer system. An evaluation of the system s present state and an estimate of the cost to bring it back to operational status was also produced.

  8. Combined Effect of Thermosonication and Slightly Acidic Electrolyzed Water to Reduce Foodborne Pathogens and Spoilage Microorganisms on Fresh-cut Kale.

    Science.gov (United States)

    Mansur, Ahmad Rois; Oh, Deog-Hwan

    2015-06-01

    This study evaluated the efficacy of individual treatments (thermosonication [TS+DW] and slightly acidic electrolyzed water [SAcEW]) and their combination on reducing Escherichia coli O157:H7, Listeria monocytogenes, and spoilage microorganisms (total bacterial counts [TBC], Enterobacteriaceae, Pseudomonas spp., and yeast and mold counts [YMC]) on fresh-cut kale. For comparison, the antimicrobial efficacies of sodium chlorite (SC; 100 mg/L) and sodium hypochlorite (SH; 100 mg/L) were also evaluated. Each 10 g sample of kale leaves was inoculated to contain approximately 6 log CFU/g of E. coli O157:H7 or L. monocytogenes. Each inoculated or uninoculated samples was then dip treated with deionized water (DW; control), TS+DW, and SAcEW at various treatment conditions (temperature, physicochemical properties, and time) to assess the efficacy of each individual treatment. The efficacy of TS+DW or SAcEW was enhanced at 40 °C for 3 min, with an acoustic energy density of 400 W/L for TS+DW and available chlorine concentration of 5 mg/L for SAcEW. At 40 °C for 3 min, combined treatment of thermosonication 400 W/L and SAcEW 5 mg/L (TS+SAcEW) was more effective in reducing microorganisms compared to the individual treatments (SAcEW, SC, SH, and TS+DW) and combined treatments (TS+SC and TS+SH), which significantly (P 3.24 log CFU/g, respectively. The results suggest that the combined treatment of TS+SAcEW has the potential as a decontamination process in fresh-cut industry. © 2015 Institute of Food Technologists®

  9. Combined effects of thermosonication and slightly acidic electrolyzed water on the microbial quality and shelf life extension of fresh-cut kale during refrigeration storage.

    Science.gov (United States)

    Mansur, Ahmad Rois; Oh, Deog-Hwan

    2015-10-01

    This study evaluated the efficacy of thermosonication combined with slightly acidic electrolyzed water (SAcEW) on the shelf life extension of fresh-cut kale during storage at 4 and 7 °C. Each kale (10 ± 0.2 g) was inoculated to contain approximately 6 log CFU/g of Listeria monocytogenes. Each inoculated or uninoculated samples was dip treated at 40 °C for 3 min with deionized water, thermosonication (400 W/L), SAcEW (5 mg/L), sodium chlorite (SC; 100 mg/L), sodium hypochlorite (SH; 100 mg/L), and thermosonication combined with SAcEW, SC, and SH (TS + SAcEW, TS + SC, and TS + SH, respectively). Growths of L. monocytogenes and spoilage microorganisms and changes in sensory (overall visual quality, browning, and off-odour) were evaluated. The results show that lag time and specific growth rate of each microorganism were not significantly (P > 0.05) affected by treatment and storage temperature. Exceeding the unacceptable counts of spoilage microorganisms did not always result in adverse effects on sensory attributes. This study suggests that TS + SAcEW was the most effective method to prolong the shelf life of kale with an extension of around 4 and 6 days at 4 and 7 °C, respectively, and seems to be a promising method for the shelf life extension of fresh produce. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. A Stability Study of Alkali Doped PBI Membranes for Alkaline Electrolyzer Cells

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Aili, David; Hansen, Martin Kalmar

    2014-01-01

    conductivity was similar to a commercial Zirfon membrane and suitable for a water electrolyzer. Some chemical degradation was seen during the aging period, but the crosslinked and the cured materials were both integral after 176 days of aging. A simplified electrolyzer test cell was operated successfully....

  11. Proceedings of the 19. IAHR international symposium on ice : using new technology to understand water-ice interaction

    International Nuclear Information System (INIS)

    Jasek, M.; Andrishak, R.; Siddiqui, A.

    2008-01-01

    This conference provided a venue for scientists, engineers and researchers an opportunity to expand their knowledge of water-ice interactions with reference to water resources, river and coastal hydraulics, risk analysis, energy and the environment. The the theme of new technology falls into 3 basic groups, notably measurement and instrumentation; remote sensing; and numerical simulation. The thermal regime of rivers was discussed along with ice mechanics, ice hydraulics, ice structures and modelling ice phenomena. The titles of the sessions were: river ice, glaciers and climate change; freeze-up processes on rivers and oceans; river ice-structure interactions; numerical simulations in ice engineering; river-ice break-up and ice jam formation; ice measurement; Grasse River ice evaluation; evaluation of structural ice control alternatives; remote sensing; hydropower and dam decommissioning; mechanical behaviour of river ice, ice covered flow and thermal modelling; mathematical and computer model formulations for ice friction and sea ice; ice bergs and ice navigation; ice crushing processes; sea ice and shore/structure interactions; ice properties, testing and physical modelling; ice actions on compliant structures; oil spills in ice; desalination, ice thickness and climate change; and, sea ice ridges. The conference featured 123 presentations, of which 20 have been catalogued separately for inclusion in this database. refs., tabs., figs

  12. Assimilation of ice and water observations from SAR imagery to improve estimates of sea ice concentration

    Directory of Open Access Journals (Sweden)

    K. Andrea Scott

    2015-09-01

    Full Text Available In this paper, the assimilation of binary observations calculated from synthetic aperture radar (SAR images of sea ice is investigated. Ice and water observations are obtained from a set of SAR images by thresholding ice and water probabilities calculated using a supervised maximum likelihood estimator (MLE. These ice and water observations are then assimilated in combination with ice concentration from passive microwave imagery for the purpose of estimating sea ice concentration. Due to the fact that the observations are binary, consisting of zeros and ones, while the state vector is a continuous variable (ice concentration, the forward model used to map the state vector to the observation space requires special consideration. Both linear and non-linear forward models were investigated. In both cases, the assimilation of SAR data was able to produce ice concentration analyses in closer agreement with image analysis charts than when assimilating passive microwave data only. When both passive microwave and SAR data are assimilated, the bias between the ice concentration analyses and the ice concentration from ice charts is 19.78%, as compared to 26.72% when only passive microwave data are assimilated. The method presented here for the assimilation of SAR data could be applied to other binary observations, such as ice/water information from visual/infrared sensors.

  13. Experimental and thermodynamic study on the performance of water electrolysis by solid oxide electrolyzer cells with Nb-doped Co-based perovskite anode

    International Nuclear Information System (INIS)

    Pan, Zehua; Liu, Qinglin; Zhang, Lan; Zhou, Juan; Zhang, Caizhi; Chan, Siew Hwa

    2017-01-01

    Highlights: • BCFN was applied on traditional YSZ electrolyte with GDC interlayer. • Dense YSZ-GDC bilayer electrolyte was obtained by co-sintering at 1300 °C. • Area specific resistance of full cell is 0.195 Ω cm"2 at 800 °C with 60% water vapor. • Cell voltage is 1.13 V at 1 A cm"−"2 at 800 °C with feedstock of 60% H_2O-40% H_2. • The electricity to hydrogen efficiency is 73% with generation rate of 4180 L h"−"1 m"−"2. - Abstract: In this work, Solid Oxide Electrolyzer Cell (SOEC) based on Ba_0_._9Co_0_._7Fe_0_._2Nb_0_._1O_3_-_δ (BCFN) air electrode and YSZ-GDC bilayer electrolyte was systematically investigated and the efficiency of high-temperature water electrolysis by such a cell was analyzed. Firstly, chemical compatibility test between BCFN and YSZ showed that BaZrO_3 formed after heat treatment at 1000 °C for 5 h, which adversely influenced the performance of BCFN dramatically. A fully dense GDC interlayer was thus developed by co-sintering GDC layer, with addition of 0.5 at.% Fe_2O_3, with YSZ electrolyte at only 1300 °C. The as-prepared fuel electrode-supported eletrolyzer cell consisting of Ni-YSZ fuel electrode, YSZ-GDC bilayer electrolyte and BCFN air electrode was evaluated for water electrolysis. Specifically, at 800 °C using a feedstock of 60% H_2O-40% H_2, the cell showed total area specific resistance of 0.195 Ω cm"2 and the cell voltage was 1.13 V with an electrolysis current of 1 A cm"−"2. After short-term stability test for 120 h with 1 A cm"−"2 electrolysis current at 800 °C, the cell showed no microstructural changes as observed by scanning electron microscopy. At last, a high-temperature water electrolysis system based on the cell studied was proposed and the system analysis shows that the overall electricity to hydrogen efficiency can reach 73% based on lower heating value of hydrogen, with a hydrogen generation rate of 4180 L h"−"1 m"−"2.

  14. Experimental study on the influence of clamping pressure on proton exchange membrane water electrolyzer (PEMWE) cell’s characteristics

    DEFF Research Database (Denmark)

    Al Shakhshir, Saher; Cui, Xiaoti; Kær, Søren Knudsen

    Energy transition can be led by more hydrogen production. Hydrogen offers a clean, sustainable, and flexible option for overcoming different obstacles that face the low-carbon economy [1]. PEMWE is one of the most promising candidate technologies to produce hydrogen from renewable energy sources...... with the circulating water. In the recent few years, PEMWE’s R&D has inched towards; operating conditions; such as increased operating temperature and cathode-anode high differential pressure operation, flow field design, stack development, and numerical modelling [2,3]. In this work the effect of clamping pressure...... on the PEMWE cell characteristics’; performance, conductivity, hydrogen and water cross-over through the membrane electrode assembly (MEA) is studied. A 50 cm2 active area PEMWE cell with double serpentine flow field channels for the anode and cathode side is used. Measurements are carried out at constant cell...

  15. Efficacy of slightly acidic electrolyzed water in killing or reducing Escherichia coli O157:H7 on iceberg lettuce and tomatoes under simulated food service operation conditions.

    Science.gov (United States)

    Pangloli, Philipus; Hung, Yen-Con

    2011-08-01

    The objective of this study was to evaluate the efficacy of slightly acidic electrolyzed (SAEO) water in killing or removing Escherichia coli O157:H7 on iceberg lettuce and tomatoes by washing and chilling treatment simulating protocols used in food service kitchens. Whole lettuce leaves and tomatoes were spot-inoculated with 100 μL of a mixture of 5 strains of E. coli O157:H7. Washing lettuce with SAEO water for 15 s reduced the pathogen by 1.4 to 1.6 log CFU/leaf, but the treatments did not completely inactivate the pathogen in the wash solution. Increasing the washing time to 30 s increased the reductions to 1.7 to 2.3 log CFU/leaf. Sequential washing in SAEO water for 15 s and then chilling in SAEO water for 15 min also increased the reductions to 2.0 to 2.4 log CFU/leaf, and no cell survived in chilling solution after treatment. Washing tomatoes with SAEO water for 8 s reduced E. coli O157:H7 by 5.4 to 6.3 log CFU/tomato. The reductions were increased to 6.6 to 7.6 log CFU/tomato by increasing the washing time to 15 s. Results suggested that application of SAEO water to wash and chill lettuce and tomatoes in food service kitchens could minimize cross-contamination and reduce the risk of E. coli O157:H7 present on the produce. SAEO water is equally or slightly better than acidic electrolyzed (AEO) water for inactivation of bacteria on lettuce and tomato surfaces. In addition, SAEO water may have the advantages over AEO water on its stability, no chlorine smell, and low corrosiveness. Therefore, SAEO water may have potential for produce wash to enhance food safety. © 2011 Institute of Food Technologists®

  16. Free chlorine loss during spraying of membraneless acidic electrolyzed water and its antimicrobial effect on airborne bacteria from poultry house

    Directory of Open Access Journals (Sweden)

    Yang Zhao

    2014-06-01

    Full Text Available introduction. Spray-application of membraneless acidic electrolyzed water (MLAEW is a novel technique for disinfection in livestock houses. This study investigated the loss of free chlorine (FC – the major germicidal component in MLAEW over distance during spraying, as affected by air temperature and initial FC concentration. The anti-microbial effect of MLAEW on airborne bacteria from an aviary laying-hen house was examined. materials and methods. MLAEW was prepared at two FC concentrations: app. 15 and 60 mg L -1 , and sprayed at three air temperatures (18, 25, 32 °C. The original MLAEW solution and MLAEW aerosols collected at 0, 25, and 50 cm from the spray nozzle were analyzed for FC concentrations. Bacteria were immersed into these MLAEW samples and numerated for viable count after 0.5, 2 and 5-min treatments. results. MLAEW aerosols collected at 0 cm lost 11.7–13.2% FC, compared with the original MLAEW solution. This initial loss was affected neither by the initial FC concentration (P = 0.13 nor by air temperature (P = 0.57. The rate of FC loss during travelling was 0.79–0.87 % per cm of aerosol travel distance (% cm -1 at 18 °C, 1.08–1.15 % cm -1 at 25 °C, and 1.35–1.49% cm -1 at 32 °C. This travelling loss was affected by air temperature (P = 0.02, but not by initial FC concentration (P = 0.38. Bacteria were completely inactivated at 0.5 min when treated with MLAEW samples with FC > 16.8 mg L -1 , in 2 min when FC > 13.8 mg L -1 , and in 5 min when FC > 7.2 mg L -1 . conclusion. Airborne bacteria from aviary hen house can be effectively inactivated by MLAEW with adequate FC concentration and contact time. During spraying, the anti-microbial efficacy of MLAEW aerosols decreased over distance due to FC loss which exacerbated at higher air temperatures.

  17. Export of Ice-Cavity Water from Pine Island Ice Shelf, West Antarctica

    Science.gov (United States)

    Thurnherr, Andreas; Jacobs, Stanley; Dutrieux, Pierre

    2013-04-01

    Stability of the West Antarctic Ice Sheet is sensitive to changes in melting at the bottom of floating ice shelves that form the seaward extensions of Antarctic glaciers flowing into the ocean. Not least because observations in the cavities beneath ice shelves are difficult, heat fluxes and melt rates have been inferred from oceanographic measurements obtained near the ice edge (calving fronts). Here, we report on a set of hydrographic and velocity data collected in early 2009 near the calving front of the Amundsen Sea's fast-moving and (until recently) accelerating Pine Island Glacier and its associated ice shelf. CTD profiles collected along the southern half of the meridionally-trending ice front show clear evidence for export of ice-cavity water. That water was carried in the upper ocean along the ice front by a southward current that is possibly related to a striking clockwise gyre that dominated the (summertime) upper-ocean circulation in Pine Island Bay. Signatures of ice-cavity water appear unrelated to current direction along most of the ice front, suggesting that cross-frontal exchange is dominated by temporal variability. However, repeated hydrographic and velocity measurements in a small "ice cove" at the southern end of the calving front show a persistent strong (mean velocity peaking near 0.5 ms-1) outflow of ice-cavity water in the upper 500 m. While surface features (boils) suggested upwelling from deep below the ice shelf, vertical velocity measurements reveal 1) that the mean upwelling within the confines of the cove was too weak to feed the observed outflow, and 2) that large high-frequency internal waves dominated the vertical motion of water inside the cove. These observations indicate that water exchange between the Pine Island Ice Shelf cavity and the Amundsen sea is strongly asymmetric with weak broad inflow at depth and concentrated surface-intensified outflow of melt-laden deep water at the southern edge of the calving front. The lack of

  18. Water, ice and mud: Lahars and lahar hazards at ice- and snow-clad volcanoes

    Science.gov (United States)

    Waythomas, Christopher F.

    2014-01-01

    Large-volume lahars are significant hazards at ice and snow covered volcanoes. Hot eruptive products produced during explosive eruptions can generate a substantial volume of melt water that quickly evolves into highly mobile flows of ice, sediment and water. At present it is difficult to predict the size of lahars that can form at ice and snow covered volcanoes due to their complex flow character and behaviour. However, advances in experiments and numerical approaches are producing new conceptual models and new methods for hazard assessment. Eruption triggered lahars that are ice-dominated leave behind thin, almost unrecognizable sedimentary deposits, making them likely to be under-represented in the geological record.

  19. Could the Hokusai Impact Have Delivered Mercury's Water Ice?

    Science.gov (United States)

    Ernst, C. M.; Chabot, N. L.; Barnouin, O. S.

    2018-05-01

    Hokusai is the best candidate source crater for Mercury’s water-ice inventory if it was primarily delivered by a single impact event. The Hokusai impact could account for the inventory of water ice on Mercury for impact velocities <30 km/s.

  20. Proton dynamics and the phase diagram of dense water ice.

    Science.gov (United States)

    Hernandez, J-A; Caracas, R

    2018-06-07

    All the different phases of water ice between 2 GPa and several megabars are based on a single body-centered cubic sub-lattice of oxygen atoms. They differ only by the behavior of the hydrogen atoms. In this study, we investigate the dynamics of the H atoms at high pressures and temperatures in water ice from first-principles molecular dynamics simulations. We provide a detailed analysis of the O-H⋯O bonding dynamics over the entire stability domain of the body-centered cubic (bcc) water ices and compute transport properties and vibrational density-of-states. We report the first ab initio evidence for a plastic phase of water and we propose a coherent phase diagram for bcc water ices compatible with the two groups of melting curves and with the multiple anomalies reported in ice VII around 15 GPa.

  1. Electrolyzer assembly method and system

    Energy Technology Data Exchange (ETDEWEB)

    Swala, Dana Ray; Bourgeois, Richard Scott; Paraszczak, Steven; Buckley, Donald Joseph

    2017-05-23

    The present techniques provide a novel electrolyzer and methods for welding components of such electrolyzers. The techniques may use conductors, such as resistance wires, placed in paths around the internal structural features and edges of the components. The conductors may be incorporated into the components during manufacture by injection molding, or other molding techniques, or may be tacked or otherwise applied to the surface of the components after manufacture. When current, a field or other excitation is applied to the conductors, the plastic surrounding the wire is melted. If this plastic is in direct contact with an adjoining component, a strong, hermetic seal may be formed between the two components, including the internal structural features.

  2. Composite Bipolar Plate for Unitized Fuel Cell/Electrolyzer Systems

    Science.gov (United States)

    Mittelsteadt, Cortney K.; Braff, William

    2009-01-01

    In a substantial improvement over present alkaline systems, an advanced hybrid bipolar plate for a unitized fuel cell/electrolyzer has been developed. This design, which operates on pure feed streams (H2/O2 and water, respectively) consists of a porous metallic foil filled with a polymer that has very high water transport properties. Combined with a second metallic plate, the pore-filled metallic plates form a bipolar plate with an empty cavity in the center.

  3. Radiation Chemistry in Ammonia-Water Ices

    Science.gov (United States)

    Loeffler, M. J.; Raut, U.; Baragiola, R. A.

    2010-01-01

    We studied the effects of 100 keV proton irradiation on films of ammonia-water mixtures between 20 and 120 K. Irradiation destroys ammonia, leading to the formation and trapping of H2, N2 NO, and N2O, the formation of cavities containing radiolytic gases, and ejection of molecules by sputtering. Using infrared spectroscopy, we show that at all temperatures the destruction of ammonia is substantial, but at higher temperatures (120 K), it is nearly complete (approximately 97% destroyed) after a fluence of 10(exp 16) ions per square centimeter. Using mass spectroscopy and microbalance gravimetry, we measure the sputtering yield of our sample and the main components of the sputtered flux. We find that the sputtering yield depends on fluence. At low temperatures, the yield is very low initially and increases quadratically with fluence, while at 120 K the yield is constant and higher initially. The increase in the sputtering yield with fluence is explained by the formation and trapping of the ammonia decay products, N2 and H2 which are seen to be ejected from the ice at all temperatures.

  4. Water ice grains in comet C/2013 US10 (Catalina)

    Science.gov (United States)

    Protopapa, Silvia; Kelley, Michael S. P.; Yang, Bin; Woodward, Charles E.; Sunshine, Jessica M.

    2017-10-01

    Knowledge of the the physical properties of water ice in cometary nuclei is critical in determining how the Solar System was formed. While it is difficult to directly study the properties of water ice in comet nuclei, we can study comet interiors through their comae. Cometary activity makes the interiors of these objects available for characterization. However, the properties (grain size, abundance, purity, chemical state) of water-ice grains detected in the coma do not necessarily represent the characteristics of the water ice on the surface and/or in the interior of the nucleus. This is due to the potential physical and chemical evolution of the emitted material. Once in the coma, water-ice grains are heated by sunlight, and if temperatures are warm enough, they sublime. In this case, their sizes and potentially their ice-to-dust fractions are reduced.We present IRTF/SpeX measurements of the Oort cloud comet C/2013 US10 (Catalina), which reached perihelion in Nov 2015 at a heliocentric distance Rh=0.822 AU. Observations of US10 were acquired on UT 2014-08-13, 2016-01-12, and 2016-08-13 (Rh=5.9, 1.3, and 3.9 AU). This set of measurements, spanning a broad range in Rh, are rare and fundamental for estimating how ice grains evolve in the coma. The spectrum obtained close to perihelion is featureless and red sloped, which is consistent with a dust-dominated coma. Conversely, the spectra acquired on August 2014 and 2016 display neutral slopes and absorption bands at 1.5 and 2.0 μm, consistent with the presence of water-ice grains. These variations in water ice with heliocentric distance are correlated with sublimation rates. Additionally, the measurements obtained at 5.8 AU and 3.9 AU are nearly identical, suggesting that water-ice grains, once in the coma, do not sublime significantly. Therefore, the properties of these long-lived water-ice grains may represent their state in the nucleus or immediately after insertion into the coma. We will present radiative

  5. Positron Lifetimes in Pure and Doped Ice and in Water

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard; Mogensen, O.; Trumpy, Georg

    1972-01-01

    for the other components show a complex behavior. The spectra for mono- and polycrystalline light ice and for polycrystalline heavy ice are identical. For water long lifetime components attributed to ortho-Ps are 1.86 nsec, 27% for H2O and 2.01 nsec, 22% for D2O. Theoretical explanations are suggested. Fast......Positron lifetime spectra were measured in mono- and polycrystalline light ice, polycrystalline heavy ice, doped light ice, as well as in light and heavy water. All spectra were resolved into three components. At temperatures between −196° and −100°C the lifetimes and relative intensities...... of the spectra are found by heating above approximately −120°C. Measurements on a number of fast frozen aqueous solutions of acids, bases, and salts are reported, none of them showing as strong influence on the ortho-Ps lifetime as HF. ©1972 The American Institute of Physics...

  6. Determination of ice water path in ice-over-water cloud systems using combined MODIS and AMSR-E measurements

    Science.gov (United States)

    Huang, Jianping; Minnis, Patrick; Lin, Bing; Yi, Yuhong; Fan, T.-F.; Sun-Mack, Sunny; Ayers, J. K.

    2006-11-01

    To provide more accurate ice cloud microphysical properties, the multi-layered cloud retrieval system (MCRS) is used to retrieve ice water path (IWP) in ice-over-water cloud systems globally over oceans using combined instrument data from Aqua. The liquid water path (LWP) of lower-layer water clouds is estimated from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) measurements. The properties of the upper-level ice clouds are then derived from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements by matching simulated radiances from a two-cloud-layer radiative transfer model. The results show that the MCRS can significantly improve the accuracy and reduce the over-estimation of optical depth and IWP retrievals for ice-over-water cloud systems. The mean daytime ice cloud optical depth and IWP for overlapped ice-over-water clouds over oceans from Aqua are 7.6 and 146.4 gm-2, respectively, down from the initial single-layer retrievals of 17.3 and 322.3 gm-2. The mean IWP for actual single-layer clouds is 128.2 gm-2.

  7. Ice crystallization in ultrafine water-salt aerosols: nucleation, ice-solution equilibrium, and internal structure.

    Science.gov (United States)

    Hudait, Arpa; Molinero, Valeria

    2014-06-04

    Atmospheric aerosols have a strong influence on Earth's climate. Elucidating the physical state and internal structure of atmospheric aqueous aerosols is essential to predict their gas and water uptake, and the locus and rate of atmospherically important heterogeneous reactions. Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers in the troposphere and tropopause. Nanoscopic aerosols arising from bubble bursting of natural and artificial seawater have been identified in laboratory and field experiments. The internal structure and phase state of these aerosols, however, cannot yet be determined in experiments. Here we use molecular simulations to investigate the phase behavior and internal structure of liquid, vitrified, and crystallized water-salt ultrafine aerosols with radii from 2.5 to 9.5 nm and with up to 10% moles of ions. We find that both ice crystallization and vitrification of the nanodroplets lead to demixing of pure water from the solutions. Vitrification of aqueous nanodroplets yields nanodomains of pure low-density amorphous ice in coexistence with vitrified solute rich aqueous glass. The melting temperature of ice in the aerosols decreases monotonically with an increase of solute fraction and decrease of radius. The simulations reveal that nucleation of ice occurs homogeneously at the subsurface of the water-salt nanoparticles. Subsequent ice growth yields phase-segregated, internally mixed, aerosols with two phases in equilibrium: a concentrated water-salt amorphous mixture and a spherical cap-like ice nanophase. The surface of the crystallized aerosols is heterogeneous, with ice and solution exposed to the vapor. Free energy calculations indicate that as the concentration of salt in the particles, the advance of the crystallization, or the size of the particles increase, the stability of the spherical cap structure increases with respect to the alternative structure in which a core of ice is fully surrounded by

  8. Hexagonal ice in pure water and biological NMR samples

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Thomas; Gath, Julia; Hunkeler, Andreas; Ernst, Matthias, E-mail: maer@ethz.ch [ETH Zurich, Physical Chemistry (Switzerland); Böckmann, Anja, E-mail: a.bockmann@ibcp.fr [UMR 5086 CNRS, Université de Lyon 1, Institut de Biologie et Chimie des Protéines (France); Meier, Beat H., E-mail: beme@ethz.ch [ETH Zurich, Physical Chemistry (Switzerland)

    2017-01-15

    Ice, in addition to “liquid” water and protein, is an important component of protein samples for NMR spectroscopy at subfreezing temperatures but it has rarely been observed spectroscopically in this context. We characterize its spectroscopic behavior in the temperature range from 100 to 273 K, and find that it behaves like pure water ice. The interference of magic-angle spinning (MAS) as well as rf multiple-pulse sequences with Bjerrum-defect motion greatly influences the ice spectra.

  9. When Big Ice Turns Into Water It Matters For Houses, Stores And Schools All Over

    Science.gov (United States)

    Bell, R. E.

    2017-12-01

    When ice in my glass turns to water it is not bad but when the big ice at the top and bottom of the world turns into water it is not good. This new water makes many houses, stores and schools wet. It is really bad during when the wind is strong and the rain is hard. New old ice water gets all over the place. We can not get to work or school or home. We go to the big ice at the top and bottom of the world to see if it will turn to water soon and make more houses wet. We fly over the big ice to see how it is doing. Most of the big ice sits on rock. Around the edge of the big sitting on rock ice, is really low ice that rides on top of the water. This really low ice slows down the big rock ice turning into water. If the really low ice cracks up and turns into little pieces of ice, the big rock ice will make more houses wet. We look to see if there is new water in the cracks. Water in the cracks is bad as it hurts the big rock ice. Water in the cracks on the really low ice will turn the low ice into many little pieces of ice. Then the big rock ice will turn to water. That is water in cracks is bad for the houses, schools and businesses. If water moves off the really low ice, it does not stay in the cracks. This is better for the really low ice. This is better for the big rock ice. We took pictures of the really low ice and saw water leaving. The water was not staying in the cracks. Water leaving the really low ice might be good for houses, schools and stores.

  10. Instability of water-ice interface under turbulent flow

    Science.gov (United States)

    Izumi, Norihiro; Naito, Kensuke; Yokokawa, Miwa

    2015-04-01

    It is known that plane water-ice interface becomes unstable to evolve into a train of waves. The underside of ice formed on the water surface of rivers are often observed to be covered with ice ripples. Relatively steep channels which discharge melting water from glaciers are characterized by beds covered with a series of steps. Though the flowing agent inducing instability is not water but gas including water vapor, a similar train of steps have been recently observed on the Polar Ice Caps on Mars (Spiral Troughs). They are expected to be caused by the instability of water-ice interface induced by flowing fluid on ice. There have been some studies on this instability in terms of linear stability analysis. Recently, Caporeale and Ridolfi (2012) have proposed a complete linear stability analysis in the case of laminar flow, and found that plane water-ice interface is unstable in the range of sufficiently large Reynolds numbers, and that the important parameters are the Reynolds number, the slope angle, and the water surface temperature. However, the flow inducing instability on water-ice interface in the field should be in the turbulent regime. Extension of the analysis to the case of fully developed turbulent flow with larger Reynolds numbers is needed. We have performed a linear stability analysis on the instability of water-ice interface under turbulent flow conditions with the use of the Reynolds-averaged Navier-Stokes equations with the mixing length turbulent model, the continuity equation of flow, the diffusion/dispersion equation of heat, and the Stefan equation. In order to reproduce the accurate velocity distribution and the heat transfer in the vicinity of smooth walls with the use of the mixing length model, it is important to take into account of the rapid decrease in the mixing length in the viscous sublayer. We employ the Driest model (1956) to the formulation. In addition, as the thermal boundary condition at the water surface, we describe the

  11. River ice implications related to water power production in Norway

    Energy Technology Data Exchange (ETDEWEB)

    Asvall, R.P. [Norwegian Water Resources and Energy Directorate, Oslo (Norway). Hydrology Dept.

    2009-07-01

    Nearly 99 per cent of the electricity produced in Norway is based on water power. While the period of large power development is over, the current focus lies in developing small hydroelectric power plants. A new market based energy law was implemented in Norway in 1991 to achieve more efficient use of electricity production by means of market forces. Since water regulation influences ice conditions in lakes and rivers, this paper focused on the implications of changes in ice conditions. In Norway, the expected changes in ice conditions are taken into account when issuing permits for water regulations and schemes for water discharge because some waterways are used as winter roads. Follow-up includes both close and long term observations and measurements. The impact of variable price on power was also discussed, with particular reference to ice conditions in cases where water discharge occurs on rivers. This paper summarized selected ice problems and how they have been handled. The paper also included a summary of anticipated climatic changes relevant to ice conditions.

  12. River ice implications related to water power production in Norway

    International Nuclear Information System (INIS)

    Asvall, R.P.

    2009-01-01

    Nearly 99 per cent of the electricity produced in Norway is based on water power. While the period of large power development is over, the current focus lies in developing small hydroelectric power plants. A new market based energy law was implemented in Norway in 1991 to achieve more efficient use of electricity production by means of market forces. Since water regulation influences ice conditions in lakes and rivers, this paper focused on the implications of changes in ice conditions. In Norway, the expected changes in ice conditions are taken into account when issuing permits for water regulations and schemes for water discharge because some waterways are used as winter roads. Follow-up includes both close and long term observations and measurements. The impact of variable price on power was also discussed, with particular reference to ice conditions in cases where water discharge occurs on rivers. This paper summarized selected ice problems and how they have been handled. The paper also included a summary of anticipated climatic changes relevant to ice conditions.

  13. Dynamics of ice nucleation on water repellent surfaces.

    Science.gov (United States)

    Alizadeh, Azar; Yamada, Masako; Li, Ri; Shang, Wen; Otta, Shourya; Zhong, Sheng; Ge, Liehui; Dhinojwala, Ali; Conway, Ken R; Bahadur, Vaibhav; Vinciquerra, A Joseph; Stephens, Brian; Blohm, Margaret L

    2012-02-14

    Prevention of ice accretion and adhesion on surfaces is relevant to many applications, leading to improved operation safety, increased energy efficiency, and cost reduction. Development of passive nonicing coatings is highly desirable, since current antiicing strategies are energy and cost intensive. Superhydrophobicity has been proposed as a lead passive nonicing strategy, yet the exact mechanism of delayed icing on these surfaces is not clearly understood. In this work, we present an in-depth analysis of ice formation dynamics upon water droplet impact on surfaces with different wettabilities. We experimentally demonstrate that ice nucleation under low-humidity conditions can be delayed through control of surface chemistry and texture. Combining infrared (IR) thermometry and high-speed photography, we observe that the reduction of water-surface contact area on superhydrophobic surfaces plays a dual role in delaying nucleation: first by reducing heat transfer and second by reducing the probability of heterogeneous nucleation at the water-substrate interface. This work also includes an analysis (based on classical nucleation theory) to estimate various homogeneous and heterogeneous nucleation rates in icing situations. The key finding is that ice nucleation delay on superhydrophobic surfaces is more prominent at moderate degrees of supercooling, while closer to the homogeneous nucleation temperature, bulk and air-water interface nucleation effects become equally important. The study presented here offers a comprehensive perspective on the efficacy of textured surfaces for nonicing applications.

  14. Electrolyzers Enhancing Flexibility in Electric Grids

    Directory of Open Access Journals (Sweden)

    Manish Mohanpurkar

    2017-11-01

    Full Text Available This paper presents a real-time simulation with a hardware-in-the-loop (HIL-based approach for verifying the performance of electrolyzer systems in providing grid support. Hydrogen refueling stations may use electrolyzer systems to generate hydrogen and are proposed to have the potential of becoming smarter loads that can proactively provide grid services. On the basis of experimental findings, electrolyzer systems with balance of plant are observed to have a high level of controllability and hence can add flexibility to the grid from the demand side. A generic front end controller (FEC is proposed, which enables an optimal operation of the load on the basis of market and grid conditions. This controller has been simulated and tested in a real-time environment with electrolyzer hardware for a performance assessment. It can optimize the operation of electrolyzer systems on the basis of the information collected by a communication module. Real-time simulation tests are performed to verify the performance of the FEC-driven electrolyzers to provide grid support that enables flexibility, greater economic revenue, and grid support for hydrogen producers under dynamic conditions. The FEC proposed in this paper is tested with electrolyzers, however, it is proposed as a generic control topology that is applicable to any load.

  15. WATER ICE AT THE SURFACE OF THE HD 100546 DISK

    Energy Technology Data Exchange (ETDEWEB)

    Honda, M. [Department of Physics, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830-0011 (Japan); Kudo, T.; Terada, H.; Takato, N. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, Hawaii 96720 (United States); Takatsuki, S.; Nakamoto, T. [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Inoue, A. K. [College of General Education, Osaka Sangyo University, Daito, Osaka 574-8530 (Japan); Fukagawa, M.; Tamura, M. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2016-04-10

    We made near-infrared multicolor imaging observations of a disk around Herbig Be star HD 100546 using Gemini/NICI. K (2.2 μm), H{sub 2}O ice (3.06 μm), and L′ (3.8 μm) disk images were obtained and we found a 3.1 μm absorption feature in the scattered light spectrum, likely due to water ice grains at the disk surface. We compared the observed depth of the ice absorption feature with the disk model based on Oka et al., including the water ice photodesorption effect by stellar UV photons. The observed absorption depth can be explained by both the disk models with and without the photodesorption effect within the measurement accuracy, but the model with photodesorption effects is slightly more favored, implying that the UV photons play an important role in the survival/destruction of ice grains at the Herbig Ae/Be disk surface. Further improvement to the accuracy of the observations of the water ice absorption depth is needed to constrain the disk models.

  16. WATER ICE AT THE SURFACE OF THE HD 100546 DISK

    International Nuclear Information System (INIS)

    Honda, M.; Kudo, T.; Terada, H.; Takato, N.; Takatsuki, S.; Nakamoto, T.; Inoue, A. K.; Fukagawa, M.; Tamura, M.

    2016-01-01

    We made near-infrared multicolor imaging observations of a disk around Herbig Be star HD 100546 using Gemini/NICI. K (2.2 μm), H 2 O ice (3.06 μm), and L′ (3.8 μm) disk images were obtained and we found a 3.1 μm absorption feature in the scattered light spectrum, likely due to water ice grains at the disk surface. We compared the observed depth of the ice absorption feature with the disk model based on Oka et al., including the water ice photodesorption effect by stellar UV photons. The observed absorption depth can be explained by both the disk models with and without the photodesorption effect within the measurement accuracy, but the model with photodesorption effects is slightly more favored, implying that the UV photons play an important role in the survival/destruction of ice grains at the Herbig Ae/Be disk surface. Further improvement to the accuracy of the observations of the water ice absorption depth is needed to constrain the disk models

  17. A scheme for parameterizing ice cloud water content in general circulation models

    Science.gov (United States)

    Heymsfield, Andrew J.; Donner, Leo J.

    1989-01-01

    A method for specifying ice water content in GCMs is developed, based on theory and in-cloud measurements. A theoretical development of the conceptual precipitation model is given and the aircraft flights used to characterize the ice mass distribution in deep ice clouds is discussed. Ice water content values derived from the theoretical parameterization are compared with the measured values. The results demonstrate that a simple parameterization for atmospheric ice content can account for ice contents observed in several synoptic contexts.

  18. Nye Lecture: Water Under Ice: Curiosities, Complexities, and Catastrophes

    Science.gov (United States)

    Clarke, G. K.

    2006-12-01

    Meltwater beneath glaciers and ice sheets activates some of the most curious and impressive phenomena known to glaciology. These range from the generation of miniscule electrokinetic currents by water flow through subglacial sediment to massive outburst floods that rearrange landscapes and deliver freshwater pulses to the ocean. The source of this water varies but is some mix of surface water and water melted from the glacier base by geothermal and frictional heating. The outflow of subglacial water is somewhat affected by bed topography but the dominant influence is from gradients in ice overburden pressure and thus from the surface topography of the ice sheet. Upslope water flow is possible and large adverse bed slopes are required before topographic water traps can exist. As a consequence, subglacial topographic basins tend to be leaky and less than 5% of the area of the contemporary Antarctic Ice Sheet provides suitable habitat for subglacial lakes. Following a variety of subglacial pathways, water can migrate toward the ice margins, either as a liquid or as refrozen meltwater accreted to the ice base. The morphology of the subglacial water system is thought to comprise a combination of sheet-like, channel-like, and vein-like elements, all of which lend themselves to mathematical representation. Water transport processes need not operate in a steady fashion and morphological switching between sheet-like and channel-like endmembers is linked to spectacular events such as glacier surges and outburst floods. Large outbursts of proglacially or subglacially-stored meltwater, the classic Icelandic j{ö}kulhaups, continue to occur in glaciated regions of the world and much larger floods were released during the Late Pleistocene--Early Holocene deglaciation of the Northern Hemisphere. Whether large subglacial lakes like Lake Vostok, Earth's seventh largest lake, have similar potential for delivering cataclysmic floods remains uncertain. The recent detection of a small

  19. Efficacy of Neutral pH Electrolyzed Water in Reducing Escherichia coli O157:H7 and Salmonella Typhimurium DT 104 on Fresh Produce Items using an Automated Washer at Simulated Food Service Conditions.

    Science.gov (United States)

    Afari, George K; Hung, Yen-Con; King, Christopher H

    2015-08-01

    The objective of this study was to determine the efficacy of neutral pH electrolyzed (NEO) water (155 mg/L free chlorine, pH 7.5) in reducing Escherichia coli O157:H7 and Salmonella Typhimurium DT 104 on romaine lettuce, iceberg lettuce, and tomatoes washed in an automated produce washer for different times and washing speeds. Tomatoes and lettuce leaves were spot inoculated with 100 μL of a 5 strain cocktail mixture of either pathogen and washed with 10 or 8 L of NEO water, respectively. Washing lettuce for 30 min at 65 rpm led to the greatest reductions, with 4.2 and 5.9 log CFU/g reductions achieved for E. coli O157:H7 and S. Typhimurium respectively on romaine, whereas iceberg lettuce reductions were 3.2 and 4.6 log CFU/g for E. coli O157:H7 and S. Typhimurium respectively. Washing tomatoes for 10 min at 65 rpm achieved reductions greater than 8 and 6 log CFU/tomato on S. Typhimurium and E. coli O157:H7 respectively. All pathogens were completely inactivated in NEO water wash solutions. No detrimental effects on the visual quality of the produce studied were observed under all treatment conditions. Results show the adoption of this washing procedure in food service operations could be useful in ensuring produce safety. © 2015 Institute of Food Technologists®

  20. Water ice clouds observations with PFS on Mars Express

    Science.gov (United States)

    Moroz, V. I.; Zasova, L. V.; Formisano, V.; Grassi, D.; Ignatiev, N. I.; Giuranna, M.; Maturilli, A.; Pfs Team

    The water ice cloud observation is one of the scientific goals of PFS. Presence and properties of the ice particles are identified from absorption features, observed in both spectral ranges of PFS. Being in the near perihelion condition, the temperature of the Martian atmosphere is pretty high and ice clouds exist only in some places, for example, related to topography or at north high latitudes et etc. The ice clouds are observed often above the tops of the volcanoes. We have found the ice clouds above Olympus (orbit 37) and Ascraeus Mons (orbit 68). Effective radius of particles according to the thermal IR is preliminary estimated of 1 μ m, which leads to the visual opacity of 0.2 -0.3 above Olympus and of maximum of 0.6 above Ascraeus Mons. In the case of Ascraeus Mons the ice clouds are observed on the south slope near the top of the volcano. The maximum surface temperature, observed there, results in the upward flux of warm air, which, cooling, provides the condensation of H2O. We will present a detailed analysis of the ice clouds, observed over the planet in the IR spectral range.

  1. Forced convective melting at an evolving ice-water interface

    Science.gov (United States)

    Ramudu, Eshwan; Hirsh, Benjamin; Olson, Peter; Gnanadesikan, Anand

    2015-11-01

    The intrusion of warm Circumpolar Deep Water into the ocean cavity between the base of ice shelves and the sea bed in Antarctica causes melting at the ice shelves' basal surface, producing a turbulent melt plume. We conduct a series of laboratory experiments to investigate how the presence of forced convection (turbulent mixing) changes the delivery of heat to the ice-water interface. We also develop a theoretical model for the heat balance of the system that can be used to predict the change in ice thickness with time. In cases of turbulent mixing, the heat balance includes a term for turbulent heat transfer that depends on the friction velocity and an empirical coefficient. We obtain a new value for this coefficient by comparing the modeled ice thickness against measurements from a set of nine experiments covering one order of magnitude of Reynolds numbers. Our results are consistent with the altimetry-inferred melting rate under Antarctic ice shelves and can be used in climate models to predict their disintegration. This work was supported by NSF grant EAR-110371.

  2. Exospheric transport restrictions on water ice in lunar polar traps

    Science.gov (United States)

    Hodges, R. R., Jr.

    1991-01-01

    There is little doubt that at least 10 exp 17 g of water has accreted on the moon as a result of the reduction of ferric iron at the regolith surface by solar wind protons, the vaporization of chondrites, and perhaps comet impacts. Lacking an efficient escape mechanism, most of this water (or its progeny) is probably on the moon now. If the water were to have migrated to permanently shaded cold traps near the lunar poles, ice deposts with densities greater than 1000 g/sq cm would cover the traps, providing accessible resources. However, exospheric transport considerations suggest that the actual amount of water ice in the cold traps is probably too small to be of practical interest. The alternative is global assimilation of most of the water into the regolith, a process that must account for about 30 micromoles of water per gram of soil.

  3. Water ice and sub-micron ice particles on Tethys and Mimas

    Science.gov (United States)

    Scipioni, Francesca; Nordheim, Tom; Clark, Roger Nelson; D'Aversa, Emiliano; Cruikshank, Dale P.; Tosi, Federico; Schenk, Paul M.; Combe, Jean-Philippe; Dalle Ore, Cristina M.

    2017-10-01

    IntroductionWe present our ongoing work, mapping the variation of the main water ice absorption bands, and the distribution of the sub-micron particles, across Mimas and Tethys’ surfaces using Cassini-VIMS cubes acquired in the IR range (0.8-5.1 μm). We present our results in the form of maps of variation of selected spectral indicators (depth of absorption bands, reflectance peak height, spectral slopes).Data analysisVIMS acquires hyperspectral data in the 0.3-5.1 μm spectral range. We selected VIMS cubes of Tethys and Mimas in the IR range (0.8-5.1 μm). For all pixels in the selected cubes, we measured the band depths for water-ice absorptions at 1.25, 1.5 and 2.02 μm and the height of the 3.6 μm reflection peak. Moreover, we considered the spectral indictors for particles smaller than 1 µm [1]: (i) the 2 µm absorption band is asymmetric and (ii) it has the minimum shifted to longer λ (iii) the band depth ratio 1.5/2.0 µm decreases; (iv) the reflection peak at 2.6 µm decreases; (v) the Fresnel reflection peak is suppressed; (vi) the 5 µm reflectance is decreased relative to the 3.6 µm peak. To characterize the global variation of water-ice band depths, and of sub-micron particles spectral indicators, across Mimas and Tethys, we sampled the two satellites’ surfacees with a 1°x1° fixed-resolution grid and then averaged the band depths and peak values inside each square cell.3. ResultsFor both moons we find that large geologic features, such as the Odysseus and Herschel impact basins, do not correlate with water ice’s abundance variation. For Tethys, we found a quite uniform surface on both hemispheres. The only deviation from this pattern shows up on the trailing hemisphere, where we notice two north-oriented, dark areas around 225° and 315°. For Mimas, the leading and trailing hemispheres appear to be quite similar in water ice abundance, the trailing portion having water ice absorption bands lightly more suppressed than the leading side

  4. Oxygen exchange and ice melt measured at the ice-water interface by eddy correlation

    DEFF Research Database (Denmark)

    Long, M.H.; Koopmans, D.; Berg, P.

    2012-01-01

    heterotrophic with a daily gross primary production of 0.69 mmol O2 mĝ̂'2 dĝ̂'1 and a respiration rate of ĝ̂'2.13 mmol O2 mĝ̂'2 dĝ̂'1 leading to a net ecosystem metabolism of ĝ̂'1.45 mmol O2 mĝ̂'2 dĝ̂'1. This application of the eddy correlation technique produced high temporal resolution O2 fluxes and ice melt......This study examined fluxes across the ice-water interface utilizing the eddy correlation technique. Temperature eddy correlation systems were used to determine rates of ice melting and freezing, and O2 eddy correlation systems were used to examine O2 exchange rates driven by biological and physical...

  5. Bibliography of Ice Properties and Forecasting Related to Transportation in Ice-Covered Waters.

    Science.gov (United States)

    1980-09-01

    N. and Tabata , T., Ice study in the Gulf of Peschanskii, I.S., Ice science and ice technology, Bothnia, III: observations on large grains of ice...ice and by Sterrett, K.F., The arctic environment and the hitting ice floes. Results of these measurements have arctic surface effect vehicle, Cold...ice growth, temperature 26-3673 effects, ice cover thickness. 28-557 Determining contact stresses when a ship’s stem hits the ice, Kheisin, D.E

  6. The phase diagram of water at negative pressures: virtual ices.

    Science.gov (United States)

    Conde, M M; Vega, C; Tribello, G A; Slater, B

    2009-07-21

    The phase diagram of water at negative pressures as obtained from computer simulations for two models of water, TIP4P/2005 and TIP5P is presented. Several solid structures with lower densities than ice Ih, so-called virtual ices, were considered as possible candidates to occupy the negative pressure region of the phase diagram of water. In particular the empty hydrate structures sI, sII, and sH and another, recently proposed, low-density ice structure. The relative stabilities of these structures at 0 K was determined using empirical water potentials and density functional theory calculations. By performing free energy calculations and Gibbs-Duhem integration the phase diagram of TIP4P/2005 was determined at negative pressures. The empty hydrates sII and sH appear to be the stable solid phases of water at negative pressures. The phase boundary between ice Ih and sII clathrate occurs at moderate negative pressures, while at large negative pressures sH becomes the most stable phase. This behavior is in reasonable agreement with what is observed in density functional theory calculations.

  7. Polyamorphism in Water: Amorphous Ices and their Glassy States

    Science.gov (United States)

    Amann-Winkel, K.; Boehmer, R.; Fujara, F.; Gainaru, C.; Geil, B.; Loerting, T.

    2015-12-01

    Water is ubiquitous and of general importance for our environment. But it is also known as the most anomalous liquid. The fundamental origin of the numerous anomalies of water is still under debate. An understanding of these anomalous properties of water is closely linked to an understanding of the phase diagram of the metastable non-crystalline states of ice. The process of pressure induced amorphization of ice was first observed by Mishima et al. [1]. The authors pressurized hexagonal ice at 77 K up to a pressure of 1.6 GPa to form high density amorphous ice (HDA). So far three distinct structural states of amorphous water are known [2], they are called low- (LDA), high- (HDA) and very high density amorphous ice (VHDA). Since the discovery of multiple distinct amorphous states it is controversy discussed whether this phenomenon of polyamorphism at high pressures is connected to the occurrence of more than one supercooled liquid phase [3]. Alternatively, amorphous ices have been suggested to be of nanocrystalline nature, unrelated to liquids. Indeed inelastic X-ray scattering measurements indicate sharp crystal-like phonons in the amorphous ices [4]. In case of LDA the connection to the low-density liquid (LDL) was inferred from several experiments including the observation of a calorimetric glass-to-liquid transition at 136 K and ambient pressure [5]. Recently also the glass transition in HDA was observed at 116 K at ambient pressure [6] and at 140 K at elevated pressure of 1 GPa [7], using calorimetric measurements as well as dielectric spectroscopy. We discuss here the general importance of amorphous ices and their liquid counterparts and present calorimetric and dielectric measurements on LDA and HDA. The good agreement between dielectric and calorimetric results convey for a clearer picture of water's vitrification phenomenon. [1] O. Mishima, L. D. Calvert, and E. Whalley, Nature 314, 76, 1985 [2] D.T. Bowron, J. L. Finney, A. Hallbrucker, et al., J. Chem

  8. Caltech water-ice dusty plasma: preliminary results

    Science.gov (United States)

    Bellan, Paul; Chai, Kilbyoung

    2013-10-01

    A water-ice dusty plasma laboratory experiment has begun operation at Caltech. As in Ref., a 1-5 watt parallel-plate 13.56 MHz rf discharge plasma has LN2-cooled electrodes that cool the neutral background gas to cryogenic temperatures. However, instead of creating water vapor by in-situ deuterium-oxygen bonding, here the neutral gas is argon and water vapor is added in a controlled fashion. Ice grains spontaneously form after a few seconds. Photography with a HeNe line filter of a sheet of HeNe laser light sheet illuminating a cross section of dust grains shows a large scale whorl pattern composed of concentric sub-whorls having wave-like spatially varying intensity. Each sub-whorl is composed of very evenly separated fine-scale stream-lines indicating that the ice grains move in self-organized lanes like automobiles on a multi-line highway. HeNe laser extinction together with an estimate of dust density from the intergrain spacing in photographs indicates a 5 micron nominal dust grain radius. HeNe laser diffraction patterns indicate the ice dust grains are large and ellipsoidal at low pressure (200 mT) but small and spheroidal at high pressure (>600 mT). Supported by USDOE.

  9. Water/ice phase transition: The role of zirconium acetate, a compound with ice-shaping properties

    Science.gov (United States)

    Marcellini, Moreno; Fernandes, Francisco M.; Dedovets, Dmytro; Deville, Sylvain

    2017-04-01

    Few compounds feature ice-shaping properties. Zirconium acetate is one of the very few inorganic compounds reported so far to have ice-shaping properties similar to that of ice-shaping proteins, encountered in many organisms living at low temperature. When a zirconium acetate solution is frozen, oriented and perfectly hexagonal ice crystals can be formed and their growth follows the temperature gradient. To shed light on the water/ice phase transition while freezing zirconium acetate solution, we carried out differential scanning calorimetry measurements. From our results, we estimate how many water molecules do not freeze because of their interaction with Zr cations. We estimate the colligative properties of the Zr acetate on the apparent critical temperature. We further show that the phase transition is unaffected by the nature of the base which is used to adjust the pH. Our results provide thus new hints on the ice-shaping mechanism of zirconium acetate.

  10. Electrolyzer Performance Analysis of an Integrated Hydrogen Power System for Greenhouse Heating. A Case Study

    Directory of Open Access Journals (Sweden)

    Simone Pascuzzi

    2016-07-01

    Full Text Available A greenhouse containing an integrated system of photovoltaic panels, a water electrolyzer, fuel cells and a geothermal heat pump was set up to investigate suitable solutions for a power system based on solar energy and hydrogen, feeding a self-sufficient, geothermal-heated greenhouse. The electricity produced by the photovoltaic source supplies the electrolyzer; the manufactured hydrogen gas is held in a pressure tank. In these systems, the electrolyzer is a crucial component; the technical challenge is to make it work regularly despite the irregularity of the solar source. The focus of this paper is to study the performance and the real energy efficiency of the electrolyzer, analyzing its operational data collected under different operating conditions affected by the changeable solar radiant energy characterizing the site where the experimental plant was located. The analysis of the measured values allowed evaluation of its suitability for the agricultural requirements such as greenhouse heating. On the strength of the obtained result, a new layout of the battery bank has been designed and exemplified to improve the performance of the electrolyzer. The evaluations resulting from this case study may have a genuine value, therefore assisting in further studies to better understand these devices and their associated technologies.

  11. Radiation Effects in Hydrogen-Laden Porous Water Ice Films: Implications for Interstellar Ices

    Science.gov (United States)

    Raut, Ujjwal; Baragiola, Raul; Mitchell, Emma; Shi, Jianming

    H _{2} molar remains trapped in the ice even upon removal of ambient gas-phase H _{2}, and is stable to 170 K, where the ice film desorbs. We will describe the dependence of net loss of adsorbed hydrogen on important parameters such as ice film thickness and the ratio of ion flux (f) to H _{2} flux (F _{H}). Both fluxes are higher by orders of magnitude than interstellar values. However, the information obtained from these experiments, especially the behavior in the limit of low flux (f Journal, 1983. 275: p. 391-404. 3.Shi, J., B.D. Teolis, and R.A. Baragiola, Irradiation-enhanced adsorption and trapping of O2 on nanoporous water ice. Physical Review B, 2009. 79(23): p. 235422. 4.Raut, U., et al., Compaction of microporous amorphous solid water by ion irradiation. Journal of Chemical Physics, 2007. 126(24): p. 244511.

  12. Optimization of Photovoltaic Electrolyzer Hybrid systems; taking into account the effect of climate conditions

    International Nuclear Information System (INIS)

    Sayedin, Farid; Maroufmashat, Azadeh; Sattari, Sourena; Elkamel, Ali; Fowler, Michael

    2016-01-01

    Highlights: • The optimal size of directly coupled Photovoltaic–Electrolyzer (PV/EL) is studied. • The effect of climate condition on the performance of PV/EL is studied. • PV/EL energy transfer loss and the levelized cost of hydrogen production minimized. • The model is applied to locations with different climate and solar irradiations. • Solar to electricity/electricity to hydrogen/solar to hydrogen efficiencies are derived. - Abstract: Solar energy will make a valuable contribution for power generation in the future. However the intermittency of solar energy has become an important issue in the utilization of PV system, especially small scale distributed solar energy conversion systems. The issue can be addressed through the management of production and storage of the energy in the form of hydrogen. The hydrogen can be produced by solar photovoltaic (PV) powered electrolysis of water. The amount of transferred energy to an electrolyzer from a PV module is a function of the distance between maximum power points (MPP) of PV module and the electrolyzer operating points. The distance can be minimized by optimizing the number of series and parallel units of the electrolyzer. However the maximum power points are subject to PV module characteristics, solar irradiation and ambient temperature. This means the climate condition can substantially influence the MPP and therefore the optimal size of the PV–Electrolyzer (PV/EL) system. On the other hand, system size can affect the levelized cost of hydrogen production as well. In this paper, the impact of climate conditions on the optimal size and operating conditions of a direct coupled photovoltaic–electrolyzer system has been studied. For this purpose, the optimal size of electrolyzer for six cities which have different climate condition is obtained by considering two solution scenarios, regarding two objectives which are annual energy transfer loss and levelized costs of hydrogen production and then the

  13. Corrosion behaviour of some conventional stainless steels in electrolyzing process

    Directory of Open Access Journals (Sweden)

    Amal NASSAR

    2015-12-01

    Full Text Available In this study, attempts were made to increase the amount of hydrogen generated from the water electrolysis process. Some conventional stainless steels (316; 409; 410 and 430 were used as anode and cathode in electrolysis process. Further study was carried out on the corrosion trend in all the investigated metals. It is observed that the electrode material can effect on the amount of hydrogen generate by electrolyzing process and metal composition of the stainless steels effects on the rate of corrosion.

  14. Periodic fluctuations in deep water formation due to sea ice

    Science.gov (United States)

    Saha, R.

    2012-12-01

    During the last ice age, several abrupt warming events took place, known as Dansgaard-Oeschger (D-O) events. Their effects were felt globally, although the North Atlantic experienced the largest temperature increase. The leading hypothesis to explain their occurrence postulates that the warming was caused by abrupt disruptions of the North Atlantic Current due to meltwater discharge from destabilized ice sheets (Heinrich events). However, the number of warming events outnumber the those of ice-sheet collapse. Thus, the majority of D-O events are not attributed to surface freshwater anomalies, and the underlying mechanism behind their occurrence remain unexplained. Using a simple dynamical model of sea ice and an overturning circulation, I show the existence of self-sustained relaxation oscillations in the overturning circulation. The insulating effect of sea ice is shown to paradoxically lead to a net loss of heat from the top layer of the polar ocean when sea ice retreats. Repeated heat loss results in a denser top layer and a destabilized water column, which triggers convection. The convective state pulls the system out of its preferred mode of circulation, setting up relaxation oscillations. The period of oscillations in this case is linked to the geometry of the ocean basin, if solar forcing is assumed to remain constant. If appropriate glacial freshwater forcing is applied to the model, a pattern of oscillation is produced that bears remarkable similarity to the observed fluctuations in North Atlantic climate between 50,000 and 30,000 years before present.; Comparison of NGRIP δ 18-O (proxy for near surface air temperature) between 50,000 and 30,000 years before present, showing Bond cycles (left) with the model output when forced with appropriate glacial freshwater forcing (right).

  15. Snow, ice and water in alpine regions

    International Nuclear Information System (INIS)

    Baumgartner, H.

    2009-01-01

    This article takes a look at how climate change will have a deep impact on alpine regions. The findings discussed at a conference organised by the Swiss Hydrologic Commission are presented and discussed. Flooding incidents that occurred 'once in a century' are now becoming more frequent and were considered at the conference as being an indicator of climate change. Changing hydrological factors are also discussed and the influence of climate factors in alpine regions on the water quantities in the rivers are looked at. Also, the spontaneous emptying of glacial lakes as has already happened in Switzerland and the consequences to be drawn from such incidences are discussed.

  16. Improved Instrument for Detecting Water and Ice in Soil

    Science.gov (United States)

    Buehler, Martin; Chin, Keith; Keymeulen, Didler; McCann, Timothy; Seshadri, Suesh; Anderson, Robert

    2009-01-01

    An instrument measures electrical properties of relatively dry soils to determine their liquid water and/or ice contents. Designed as a prototype of instruments for measuring the liquid-water and ice contents of lunar and planetary soils, the apparatus could also be utilized for similar purposes in research and agriculture involving terrestrial desert soils and sands, and perhaps for measuring ice buildup on aircraft surfaces. This instrument is an improved version of the apparatus described in Measuring Low Concentrations of Liquid Water and Ice in Soil (NPO-41822), NASA Tech Briefs, Vol. 33, No. 2 (February 2009), page 22. The designs of both versions are based on the fact that the electrical behavior of a typical soil sample is well approximated by a network of resistors and capacitors in which resistances decrease and capacitances increase (and the magnitude and phase angle of impedance changes accordingly) with increasing water content. The previous version included an impedance spectrometer and a jar into which a sample of soil was placed. Four stainless-steel screws at the bottom of the jar were used as electrodes of a fourpoint impedance probe connected to the spectrometer. The present instrument does not include a sample jar and can be operated without acquiring or handling samples. Its impedance probe consists of a compact assembly of electrodes housed near the tip of a cylinder. The electrodes protrude slightly from the cylinder (see Figure 1). In preparation for measurements, the cylinder is simply pushed into the ground to bring the soil into contact with the electrodes.

  17. 3 micron spectrophotometry of Comet Halley - Evidence for water ice

    Science.gov (United States)

    Bregman, Jesse D.; Tielens, A. G. G. M.; Witteborn, Fred C.; Rank, David M.; Wooden, Diane

    1988-01-01

    Structure has been observed in the 3-3.6 micron preperihelion spectrum of Comet Halley consistent with either an absorption band near 3.1 microns or emission near 3.3 microns. The results suggest that a large fraction of the water molecules lost by the comet are initially ejected in the form of small ice particles rather than in the gas phase.

  18. Nuclear Data Libraries for Hydrogen in Light Water Ice

    International Nuclear Information System (INIS)

    Torres, L; Gillette, V.H

    2000-01-01

    Nuclear data libraries were produced for hydrogen (H) in light water ice at different temperatures, 20, 30, 50, 77, 112, 180, 230 K.These libraries were produced using the NJOY nuclear data processing system.With this code we produce pointwise cross sections and related quantities, in the ENDF format, and in the ACE format for MCNP.Experimental neutron spectra at such temperatures were compared with MCNP4B simulations, based on the locally produced libraries, leading to satisfactory results

  19. Tracing Atlantic Water Signature in the Arctic Sea Ice Cover East of Svalbard

    Directory of Open Access Journals (Sweden)

    Vladimir V. Ivanov

    2012-01-01

    Full Text Available We focus on the Arctic Ocean between Svalbard and Franz Joseph Land in order to elucidate the possible role of Atlantic water (AW inflow in shaping ice conditions. Ice conditions substantially affect the temperature regime of the Spitsbergen archipelago, particularly in winter. We test the hypothesis that intensive vertical mixing at the upper AW boundary releases substantial heat upwards that eventually reaches the under-ice water layer, thinning the ice cover. We examine spatial and temporal variation of ice concentration against time series of wind, air temperature, and AW temperature. Analysis of 1979–2011 ice properties revealed a general tendency of decreasing ice concentration that commenced after the mid-1990s. AW temperature time series in Fram Strait feature a monotonic increase after the mid-1990s, consistent with shrinking ice cover. Ice thins due to increased sensible heat flux from AW; ice erosion from below allows wind and local currents to more effectively break ice. The winter spatial pattern of sea ice concentration is collocated with patterns of surface heat flux anomalies. Winter minimum sea ice thickness occurs in the ice pack interior above the AW path, clearly indicating AW influence on ice thickness. Our study indicates that in the AW inflow region heat flux from the ocean reduces the ice thickness.

  20. Radiation durability of polymeric materials in solid polymer electrolyzer for fusion tritium plant

    International Nuclear Information System (INIS)

    Iwai, Yasunori; Yamanishi, Toshihiko; Hiroki, Akihiro; Tamada, Masao

    2009-02-01

    This document presents the radiation durability of various polymeric materials applicable to a solid-polymer-electrolyte (SPE) water electrolyzer to be used in the tritium facility of fusion reactor. The SPE water electrolyzers are applied to the water detritiation system (WDS) of the ITER. In the ITER, an electrolyzer should keep its performance during two years operation in the tritiated water of 9TBq/kg, the design tritium concentration of the ITER. The tritium exposure of 9TBq/kg for two years is corresponding to the irradiation of no less than 530 kGy. In this study, the polymeric materials were irradiated with γ-rays or with electron beams at various conditions up to 1600 kGy at room temperature or at 343 K. The change in mechanical and functional properties were investigated by stress-strain measurement, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray photoelectron spectra (XPS), and so on. Our selection of polymeric materials for a SPE water electrolyzer used in a radiation environment was Pt + Ir applied Nafion N117 ion exchange membrane, VITON O-ring seal and polyimide insulator. (author)

  1. The barrier to ice nucleation in monatomic water

    Science.gov (United States)

    Prestipino, Santi

    2018-03-01

    Crystallization from a supercooled liquid initially proceeds via the formation of a small solid embryo (nucleus), which requires surmounting an activation barrier. This phenomenon is most easily studied by numerical simulation, using specialized biased-sampling techniques to overcome the limitations imposed by the rarity of nucleation events. Here, I focus on the barrier to homogeneous ice nucleation in supercooled water, as represented by the monatomic-water model, which in the bulk exhibits a complex interplay between different ice structures. I consider various protocols to identify solidlike particles on a computer, which perform well enough for the Lennard-Jones model, and compare their respective impact on the shape and height of the nucleation barrier. It turns out that the effect is stronger on the nucleus size than on the barrier height. As a by-product of the analysis, I determine the structure of the nucleation cluster, finding that the relative amount of ice phases in the cluster heavily depends on the method used for classifying solidlike particles. Moreover, the phase which is most favored during the earlier stages of crystallization may happen, depending on the nucleation coordinate adopted, to be different from the stable polymorph. Therefore, the quality of a reaction coordinate cannot be assessed simply on the basis of the barrier height obtained. I explain how this outcome is possible and why it just points out the shortcoming of collective variables appropriate to simple fluids in providing a robust method of particle classification for monatomic water.

  2. Fire, ice, water, and dirt: A simple climate model

    Science.gov (United States)

    Kroll, John

    2017-07-01

    A simple paleoclimate model was developed as a modeling exercise. The model is a lumped parameter system consisting of an ocean (water), land (dirt), glacier, and sea ice (ice) and driven by the sun (fire). In comparison with other such models, its uniqueness lies in its relative simplicity yet yielding good results. For nominal values of parameters, the system is very sensitive to small changes in the parameters, yielding equilibrium, steady oscillations, and catastrophes such as freezing or boiling oceans. However, stable solutions can be found, especially naturally oscillating solutions. For nominally realistic conditions, natural periods of order 100kyrs are obtained, and chaos ensues if the Milankovitch orbital forcing is applied. An analysis of a truncated system shows that the naturally oscillating solution is a limit cycle with the characteristics of a relaxation oscillation in the two major dependent variables, the ocean temperature and the glacier ice extent. The key to getting oscillations is having the effective emissivity decreasing with temperature and, at the same time, the effective ocean albedo decreases with increasing glacier extent. Results of the original model compare favorably to the proxy data for ice mass variation, but not for temperature variation. However, modifications to the effective emissivity and albedo can be made to yield much more realistic results. The primary conclusion is that the opinion of Saltzman [Clim. Dyn. 5, 67-78 (1990)] is plausible that the external Milankovitch orbital forcing is not sufficient to explain the dominant 100kyr period in the data.

  3. Fire, ice, water, and dirt: A simple climate model.

    Science.gov (United States)

    Kroll, John

    2017-07-01

    A simple paleoclimate model was developed as a modeling exercise. The model is a lumped parameter system consisting of an ocean (water), land (dirt), glacier, and sea ice (ice) and driven by the sun (fire). In comparison with other such models, its uniqueness lies in its relative simplicity yet yielding good results. For nominal values of parameters, the system is very sensitive to small changes in the parameters, yielding equilibrium, steady oscillations, and catastrophes such as freezing or boiling oceans. However, stable solutions can be found, especially naturally oscillating solutions. For nominally realistic conditions, natural periods of order 100kyrs are obtained, and chaos ensues if the Milankovitch orbital forcing is applied. An analysis of a truncated system shows that the naturally oscillating solution is a limit cycle with the characteristics of a relaxation oscillation in the two major dependent variables, the ocean temperature and the glacier ice extent. The key to getting oscillations is having the effective emissivity decreasing with temperature and, at the same time, the effective ocean albedo decreases with increasing glacier extent. Results of the original model compare favorably to the proxy data for ice mass variation, but not for temperature variation. However, modifications to the effective emissivity and albedo can be made to yield much more realistic results. The primary conclusion is that the opinion of Saltzman [Clim. Dyn. 5, 67-78 (1990)] is plausible that the external Milankovitch orbital forcing is not sufficient to explain the dominant 100kyr period in the data.

  4. The ancient heritage of water ice in the solar system.

    Science.gov (United States)

    Cleeves, L Ilsedore; Bergin, Edwin A; Alexander, Conel M O'D; Du, Fujun; Graninger, Dawn; Öberg, Karin I; Harries, Tim J

    2014-09-26

    Identifying the source of Earth's water is central to understanding the origins of life-fostering environments and to assessing the prevalence of such environments in space. Water throughout the solar system exhibits deuterium-to-hydrogen enrichments, a fossil relic of low-temperature, ion-derived chemistry within either (i) the parent molecular cloud or (ii) the solar nebula protoplanetary disk. Using a comprehensive treatment of disk ionization, we find that ion-driven deuterium pathways are inefficient, which curtails the disk's deuterated water formation and its viability as the sole source for the solar system's water. This finding implies that, if the solar system's formation was typical, abundant interstellar ices are available to all nascent planetary systems. Copyright © 2014, American Association for the Advancement of Science.

  5. Ice haze, snow, and the Mars water cycle

    International Nuclear Information System (INIS)

    Kahn, R.

    1990-01-01

    Images of the limb of Mars reveal discrete cloud layers between 20 and 80 km above the surface. They appear to be composed of water ice and have a number of characteristics similar to hazes that produce diamond dust precipitation in the continental Antarctic of Earth. Temperatures from 170 K to 190 K are deduced at the condensation levels. Eddy diffusion coefficients around 10 5 cm 2 s -1 , typical of a nonconvecting atmosphere, are also derived in the haze regions at times when the atmosphere is relatively clear of dust. This parameter apparently changes by more than 3 orders of magnitude with season and local conditions, with important implications for vertical transport of water and dust and for models of photochemistry and middle atmosphere dynamics. For the cases studied, particle sizes vary systematically by more than an order of magnitude with condensation level, in such a way that the characteristic fall time for particles is always about 1 Mars day, which is the dominant thermal forcing time. The hazes may play a key role in the seasonal water cycle of Mars. They provide a mechanism for growing particles large enough to move atmospheric water closer to the surface, thereby improving the efficiency of adsorption and ice deposit formation in the regolith. This is particularly likely in late northern summer, when the rapid hemispheric decrease in atmospheric water vapor may reflect the precipitation of snow. This rapid decrease in late summer involves atmospheric water vapor in about the quantities needed to supply the mid-latitude regolith with the water that appears in the atmosphere early in the following spring

  6. Thermodynamic analysis of combined Solid Oxide Electrolyzer and Fischer–Tropsch processes

    International Nuclear Information System (INIS)

    Stempien, Jan Pawel; Ni, Meng; Sun, Qiang; Chan, Siew Hwa

    2015-01-01

    In this paper a thermodynamic analysis and simple optimization of a combined Solid Oxide Electrolyzer Cell and Fisher–Tropsch Synthesis processes for sustainable hydrocarbons fuel production is reported. Comprehensive models are employed to describe effects of temperature, pressure, reactant composition and molar flux and flow on the system efficiency and final production distribution. The electrolyzer model was developed in-house and validated with experimental data of a typical Solid Oxide Electrolyzer. The Fischer–Tropsch Synthesis model employed lumped kinetics of syngas utilization, which includes inhibiting effect of water content and kinetics of Water–Gas Shift reaction. Product distribution model incorporated olefin re-adsorption and varying physisorption and solubility of hydrocarbons with their carbon number. The results were compared with those reported by Becker et al. with simplified analysis of such process. In the present study an opposite effect of operation at elevated pressure was observed. Proposed optimized system achieved overall efficiency of 66.67% and almost equal spread of light- (31%wt), mid-(36%wt) and heavy-hydrocarbons (33%wt). Paraffins contributed the majority of the yield. - Highlights: • Analysis of Solid Oxide Electrolyzer combined with Fisher Tropsch process. • Efficiency of converting water and carbon dioxide into synthetic fuels above 66%. • Effects of process temperature, pressure, gas flux and compositions were analyzed

  7. The modelled liquid water balance of the Greenland Ice Sheet

    Science.gov (United States)

    Steger, Christian R.; Reijmer, Carleen H.; van den Broeke, Michiel R.

    2017-11-01

    Recent studies indicate that the surface mass balance will dominate the Greenland Ice Sheet's (GrIS) contribution to 21st century sea level rise. Consequently, it is crucial to understand the liquid water balance (LWB) of the ice sheet and its response to increasing surface melt. We therefore analyse a firn simulation conducted with the SNOWPACK model for the GrIS and over the period 1960-2014 with a special focus on the LWB and refreezing. Evaluations of the simulated refreezing climate with GRACE and firn temperature observations indicate a good model-observation agreement. Results of the LWB analysis reveal a spatially uniform increase in surface melt (0.16 m w.e. a-1) during 1990-2014. As a response, refreezing and run-off also indicate positive changes during this period (0.05 and 0.11 m w.e. a-1, respectively), where refreezing increases at only half the rate of run-off, implying that the majority of the additional liquid input runs off the ice sheet. This pattern of refreeze and run-off is spatially variable. For instance, in the south-eastern part of the GrIS, most of the additional liquid input is buffered in the firn layer due to relatively high snowfall rates. Modelled increase in refreezing leads to a decrease in firn air content and to a substantial increase in near-surface firn temperature. On the western side of the ice sheet, modelled firn temperature increases are highest in the lower accumulation zone and are primarily caused by the exceptional melt season of 2012. On the eastern side, simulated firn temperature increases are more gradual and are associated with the migration of firn aquifers to higher elevations.

  8. The impact of radiatively active water-ice clouds on Martian mesoscale atmospheric circulations

    Science.gov (United States)

    Spiga, A.; Madeleine, J.-B.; Hinson, D.; Navarro, T.; Forget, F.

    2014-04-01

    Background and Goals Water ice clouds are a key component of the Martian climate [1]. Understanding the properties of the Martian water ice clouds is crucial to constrain the Red Planet's climate and hydrological cycle both in the present and in the past [2]. In recent years, this statement have become all the more true as it was shown that the radiative effects of water ice clouds is far from being as negligible as hitherto believed; water ice clouds plays instead a key role in the large-scale thermal structure and dynamics of the Martian atmosphere [3, 4, 5]. Nevertheless, the radiative effect of water ice clouds at lower scales than the large synoptic scale (the so-called meso-scales) is still left to be explored. Here we use for the first time mesoscale modeling with radiatively active water ice clouds to address this open question.

  9. Increased Ice-age Influence of Antarctic Intermediate Water.

    Science.gov (United States)

    Muratli, J.; McManus, J.; Mix, A.; Chase, Z.

    2008-12-01

    A depth transect of three ODP sites collected along the central Chile Margin constrain Antarctic Intermediate Water (AAIW) distributions and regional export production over the last 30 ka. Reduced Re and Cd, and increased Mn are proxies for higher bottom water oxygenation; 230Th-normalized burial of opal is a proxy for productivity. Mn/Al is high during the glacial interval at all three sites, suggesting high oxygenation and the retreat of the oxygen minimum zone during this period. At Site 1233, within the core of modern AAIW, Re and Cd are unchanged from detrital values throughout the last 30 ky, implying continuously oxic conditions. In contrast, at the northern sites 1234 and 1235, which reside below and above AAIW respectively, Re and Cd rise rapidly from low glacial values at ~15ka, signifying lower oxygen concentrations at the sea floor during Holocene time relative to ice-age conditions. Local productivity, recorded in Th-normalized opal burial, is highest during the glacial interval at both sites 1233 and 1234, and varies independently from the redox proxies. We conclude that local productivity does not drive bottom water oxygenation here, and that ventilation of the shallow subsurface southeast Pacific increased during the last ice age, with an expanded depth range of AAIW relative to the present.

  10. Accretion growth of water-ice grains in astrophysically-relevant dusty plasma experiment

    Science.gov (United States)

    Chai, Kil-Byoung; Marshall, Ryan; Bellan, Paul

    2016-10-01

    The grain growth process in the Caltech water-ice dusty plasma experiment has been studied using a high-speed camera equipped with a long-distance microscope lens. It is found that (i) the ice grain number density decreases four-fold as the average grain length increases from 20 to 80 um, (ii) the ice grain length has a log-normal distribution rather than a power-law dependence, and (iii) no collisions between ice grains are apparent. The grains have a large negative charge so the agglomeration growth is prevented by their strong mutual repulsion. It is concluded that direct accretion of water molecules is in good agreement with the observed ice grain growth. The volumetric packing factor of the ice grains must be less than 0.25 in order for the grain kinetic energy to be sufficiently small to prevent collisions between ice grains; this conclusion is consistent with ice grain images showing a fractal character.

  11. Surfacing behavior and gas release of the physostome sprat (Sprattus sprattus) in ice-free and ice-covered waters

    KAUST Repository

    Solberg, Ingrid

    2013-10-04

    Upward-facing echosounders that provided continuous, long-term measurements were applied to address the surfacing behavior and gas release of the physostome sprat (Sprattus sprattus) throughout an entire winter in a 150-m-deep Norwegian fjord. During ice-free conditions, the sprat surfaced and released gas bubbles at night with an estimated surfacing rate of 3.5 times per fish day-1. The vertical swimming speeds during surfacing were considerably higher (~10 times) than during diel vertical migrations, especially when returning from the surface, and particularly when the fjord was not ice covered. The sprat released gas a few hours after surfacing, suggesting that the sprat gulped atmospheric air during its excursions to the surface. While the surface activity increased after the fjord became ice covered, the records of gas release decreased sharply. The under-ice fish then displayed a behavior interpreted as "searching for the surface" by repeatedly ascending toward the ice, apparently with limited success of filling the swim bladder. This interpretation was supported by lower acoustic target strength in ice-covered waters. The frequent surfacing behavior demonstrated in this study indicates that gulping of atmospheric air is an important element in the life of sprat. While at least part of the population endured overwintering in the ice-covered habitat, ice covering may constrain those physostome fishes that lack a gas-generating gland in ways that remain to be established. 2013 The Author(s).

  12. Pressure Dome for High-Pressure Electrolyzer

    Science.gov (United States)

    Norman, Timothy; Schmitt, Edwin

    2012-01-01

    A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom

  13. On the Formation of Interstellar Water Ice: Constraints from a Search for Hydrogen Peroxide Ice in Molecular Clouds

    Science.gov (United States)

    Smith, R. G.; Charnely, S. B.; Pendleton, Y. J.; Wright, C. M.; Maldoni, M. M.; Robinson, G.

    2011-01-01

    Recent surface chemistry experiments have shown that the hydrogenation of molecular oxygen on interstellar dust grains is a plausible formation mechanism, via hydrogen peroxide (H2O2), for the production of water (H2O) ice mantles in the dense interstellar medium. Theoretical chemistry models also predict the formation of a significant abundance of H2O2 ice in grain mantles by this route. At their upper limits, the predicted and experimental abundances are sufficiently high that H2O2 should be detectable in molecular cloud ice spectra. To investigate this further, laboratory spectra have been obtained for H2O2/H2O ice films between 2.5 and 200 micron, from 10 to 180 K, containing 3%, 30%, and 97% H2O2 ice. Integrated absorbances for all the absorption features in low-temperature H2O2 ice have been derived from these spectra. For identifying H2O2 ice, the key results are the presence of unique features near 3.5, 7.0, and 11.3 micron. Comparing the laboratory spectra with the spectra of a group of 24 protostars and field stars, all of which have strong H2O ice absorption bands, no absorption features are found that can definitely be identified with H2O2 ice. In the absence of definite H2O2 features, the H2O2 abundance is constrained by its possible contribution to the weak absorption feature near 3.47 micron found on the long-wavelength wing of the 3 micron H2O ice band. This gives an average upper limit for H2O2, as a percentage of H2O, of 9% +/- 4%. This is a strong constraint on parameters for surface chemistry experiments and dense cloud chemistry models.

  14. Novel Electrolyzer Applications: Providing More Than Just Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Eichman, J.; Harrison, K.; Peters, M.

    2014-09-01

    Hydrogen can be used for many different applications and can be integrated into many different system architectures. One of the methods for producing the hydrogen is to use an electrolyzer. This work explores the flexibility of electrolyzers to behave as responsive loads. Experimental tests were performed for a proton exchange membrane (PEM) and an alkaline electrolyzer to assess the operational flexibility of electrolyzers to behave as responsive loads. The results are compared to the operational requirements to participate in end-user facility energy management, transmission and distribution system support, and wholesale electricity market services. Electrolyzers begin changing their electricity demand within milliseconds of a set-point change. The settling time after a set-point change is on the order of seconds. It took 6.5 minutes for the PEM unit to execute a cold start and 1 minute to turn off. In addition, a frequency disturbance correction test was performed and electrolyzers were able to accelerate the speed that the grid frequency can be restored. Electrolyzers acting as demand response devices can respond sufficiently fast and for a long enough duration to participate in all of the applications explored. Furthermore, electrolyzers can be operated to support a variety of applications while also providing hydrogen for industrial processes, transportation fuel, or heating fuel. Additionally, favorable operating properties and a variety of potential system architectures showcase the flexibility of electrolyzer systems.

  15. Effects of electrode settings on chlorine generation efficiency of electrolyzing seawater.

    Science.gov (United States)

    Hsu, Guoo-Shyng Wang; Hsia, Chih-Wei; Hsu, Shun-Yao

    2015-12-01

    Electrolyzed water has significant disinfection effects, can comply with food safety regulations, and is environmental friendly. We investigated the effects of immersion depth of electrodes, stirring, electrode size, and electrode gap on the properties and chlorine generation efficiency of electrolyzing seawater and its storage stability. Results indicated that temperature and oxidation-reduction potential (ORP) of the seawater increased gradually, whereas electrical conductivity decreased steadily in electrolysis. During the electrolysis process, pH values and electric currents also decreased slightly within small ranges. Additional stirring or immersing the electrodes deep under the seawater significantly increased current density without affecting its electric efficiency and current efficiency. Decreasing electrode size or increasing electrode gap decreased chlorine production and electric current of the process without affecting its electric efficiency and current efficiency. Less than 35% of chlorine in the electrolyzed seawater was lost in a 3-week storage period. The decrement trend leveled off after the 1 st week of storage. The electrolyzing system is a convenient and economical method for producing high-chlorine seawater, which will have high potential applications in agriculture, aquaculture, or food processing. Copyright © 2015. Published by Elsevier B.V.

  16. Effects of electrode settings on chlorine generation efficiency of electrolyzing seawater

    Directory of Open Access Journals (Sweden)

    Guoo-Shyng Wang Hsu

    2015-12-01

    Full Text Available Electrolyzed water has significant disinfection effects, can comply with food safety regulations, and is environmental friendly. We investigated the effects of immersion depth of electrodes, stirring, electrode size, and electrode gap on the properties and chlorine generation efficiency of electrolyzing seawater and its storage stability. Results indicated that temperature and oxidation-reduction potential (ORP of the seawater increased gradually, whereas electrical conductivity decreased steadily in electrolysis. During the electrolysis process, pH values and electric currents also decreased slightly within small ranges. Additional stirring or immersing the electrodes deep under the seawater significantly increased current density without affecting its electric efficiency and current efficiency. Decreasing electrode size or increasing electrode gap decreased chlorine production and electric current of the process without affecting its electric efficiency and current efficiency. Less than 35% of chlorine in the electrolyzed seawater was lost in a 3-week storage period. The decrement trend leveled off after the 1st week of storage. The electrolyzing system is a convenient and economical method for producing high-chlorine seawater, which will have high potential applications in agriculture, aquaculture, or food processing.

  17. A balanced water layer concept for subglacial hydrology in large-scale ice sheet models

    Directory of Open Access Journals (Sweden)

    S. Goeller

    2013-07-01

    Full Text Available There is currently no doubt about the existence of a widespread hydrological network under the Antarctic Ice Sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux–basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

  18. A balanced water layer concept for subglacial hydrology in large scale ice sheet models

    Science.gov (United States)

    Goeller, S.; Thoma, M.; Grosfeld, K.; Miller, H.

    2012-12-01

    There is currently no doubt about the existence of a wide-spread hydrological network under the Antarctic ice sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain inspired by the Gamburtsev Mountains, Antarctica. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux-basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out, that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

  19. The Contribution of Water Ice Clouds to the Water Cycle in the North Polar Region of Mars: Preliminary Analysis

    Science.gov (United States)

    Bass, D. S.; Tamppari, L. K.

    2000-01-01

    While it has long been known that Mars' north residual polar cap and the Martian regolith are significant sources of atmospheric water vapor, the amount of water vapor observed in the northern spring season by the Viking Mars Atmospheric Water Detector instrument (MAWD) cannot be attributed to cap and regolith sources alone. Kahn suggested that ice hazes may be the mechanism by which additional water is supplied to the Martian atmosphere. Additionally, a significant decrease in atmospheric water vapor was observed in the late northern summer that could not be correlated with the return of the cold seasonal C02 ice. While the detection of water ice clouds on Mars indicate that water exists in Mars' atmosphere in several different phases, the extent to which water ice clouds play a role in moving water through the Martian atmosphere remains uncertain. Work by Bass et. al. suggested that the time dependence of water ice cap seasonal variability and the increase in atmospheric water vapor depended on the polar cap center reaching 200K, the night time saturation temperature. Additionally, they demonstrated that a decrease in atmospheric water vapor may be attributed to deposition of water ice onto the surface of the polar cap; temperatures were still too warm at this time in the summer for the deposition of carbon dioxide. However, whether water ice clouds contribute significantly to this variability is unknown. Additional information is contained in original extended abstract.

  20. Heterogeneous Ice Nucleation: Interplay of Surface Properties and Their Impact on Water Orientations.

    Science.gov (United States)

    Glatz, Brittany; Sarupria, Sapna

    2018-01-23

    Ice is ubiquitous in nature, and heterogeneous ice nucleation is the most common pathway of ice formation. How surface properties affect the propensity to observe ice nucleation on that surface remains an open question. We present results of molecular dynamics studies of heterogeneous ice nucleation on model surfaces. The models surfaces considered emulate the chemistry of kaolinite, an abundant component of mineral dust. We investigate the interplay of surface lattice and hydrogen bonding properties in affecting ice nucleation. We find that lattice matching and hydrogen bonding are necessary but not sufficient conditions for observing ice nucleation at these surfaces. We correlate this behavior to the orientations sampled by the metastable supercooled water in contact with the surfaces. We find that ice is observed in cases where water molecules not only sample orientations favorable for bilayer formation but also do not sample unfavorable orientations. This distribution depends on both surface-water and water-water interactions and can change with subtle modifications to the surface properties. Our results provide insights into the diverse behavior of ice nucleation observed at different surfaces and highlight the complexity in elucidating heterogeneous ice nucleation.

  1. The Distribution of Basal Water Beneath the Greenland Ice Sheet from Radio-Echo Sounding

    Science.gov (United States)

    Jordan, T.; Williams, C.; Schroeder, D. M.; Martos, Y. M.; Cooper, M.; Siegert, M. J.; Paden, J. D.; Huybrechts, P.; Bamber, J. L.

    2017-12-01

    There is widespread, but often indirect, evidence that a significant fraction of the Greenland Ice Sheet is thawed at the bed. This includes major outlet glaciers and around the NorthGRIP ice-core in the interior. However, the ice-sheet-wide distribution of basal water is poorly constrained by existing observations, and the spatial relationship between basal water and other ice-sheet and subglacial properties is therefore largely unexplored. In principle, airborne radio-echo sounding (RES) surveys provide the necessary information and spatial coverage to infer the presence of basal water at the ice-sheet scale. However, due to uncertainty and spatial variation in radar signal attenuation, the commonly used water diagnostic, bed-echo reflectivity, is highly ambiguous and prone to spatial bias. Here we introduce a new RES diagnostic for the presence of basal water which incorporates both sharp step-transitions and rapid fluctuations in bed-echo reflectivity. This has the advantage of being (near) independent of attenuation model, and enables a decade of recent Operation Ice Bride RES survey data to be combined in a single map for basal water. The ice-sheet-wide water predictions are compared with: bed topography and drainage network structure, existing knowledge of the thermal state and geothermal heat flux, and ice velocity. In addition to the fast flowing ice-sheet margins, we also demonstrate widespread water routing and storage in parts of the slow-flowing northern interior. Notably, this includes a quasi-linear `corridor' of basal water, extending from NorthGRIP to Petermann glacier, which spatially correlates with a region of locally high (magnetic-derived) geothermal heat flux. The predicted water distribution places a new constraint upon the basal thermal state of the Greenland Ice Sheet, and could be used as an input for ice-sheet model simulations.

  2. Possible significance of cubic water-ice, H2O-Ic, in the atmospheric water cycle of Mars

    Science.gov (United States)

    Gooding, James L.

    1988-01-01

    The possible formation and potential significance of the cubic ice polymorph on Mars is discussed. When water-ice crystallizes on Earth, the ambient conditions of temperature and pressure result in the formation of the hexagonal ice polymorph; however, on Mars, the much lower termperature and pressures may permit the crystallization of the cubic polymorph. Cubic ice has two properties of possible importance on Mars: it is an excellant nucleator of other volatiles (such as CO2), and it undergoes an exothermic transition to hexagonal ice at temperatures above 170 K. These properties may have significant implications for both martian cloud formation and the development of the seasonal polar caps.

  3. Characterizing Water Ice Clouds on the Coldest Known Brown Dwarf

    Science.gov (United States)

    Luhman, Kevin; Burgasser, Adam; Cushing, Michael; Esplin, Taran; Fortney, Jonathan; Hardegree-Ullman, Kevin; Marley, Mark; Morley, Caroline; Schneider, Adam; Trucks, Jesica

    2014-12-01

    We have conducted a search for high proper motion brown dwarfs using multi-epoch all-sky mid-infrared images from the WISE satellite. Through this work, we have discovered an object with a parallactic distance of 2.3 pc and a temperature of 250 K, making it the 4th closest neighbor of the Sun, and the coldest known brown dwarf. Because of its extreme proximity and temperature, it represents an unparalleled laboratory for studying planet-like atmospheres in an unexplored temperature regime. We propose to photometrically monitor this object with IRAC to 1) detect and characterize water ice clouds in its atmosphere via the short-term variations induced during rotation and 2) constrain the long-term evolution of its clouds across a period of months.

  4. Experimental investigation of ice and snow melting process on pavement utilizing geothermal tail water

    International Nuclear Information System (INIS)

    Wang Huajun; Zhao Jun; Chen Zhihao

    2008-01-01

    Road ice and snow melting based on low temperature geothermal tail water is of significance to realize energy cascading utilization. A small scale ice and snow melting system is built in this work. Experiments of dynamic melting processes of crushed ice, solid ice, artificial snow and natural snow are conducted on concrete pavement. The results show that the melting process of ice and snow includes three phases: a starting period, a linear period and an accelerated period. The critical value of the snow free area ratio between the linear period and the accelerated period is about 0.6. The physical properties of ice and snow, linked with ambient conditions, have an obvious effect on the melting process. The difference of melting velocity and melting time between ice and snow is compared. To reduce energy consumption, the formation of ice on roads should be avoided if possible. The idling process is an effective pathway to improve the performance of melting systems. It is feasible to utilize geothermal tail water of about 40 deg. C for melting ice and snow on winter roads, and it is unnecessary to keep too high fluid temperatures during the practical design and applications. Besides, with the exception of solid ice, the density and porosity of snow and ice tend to be decreasing and increasing, respectively, as the ambient temperature decreases

  5. Heavy ion irradiation of crystalline water ice. Cosmic ray amorphisation cross-section and sputtering yield

    Science.gov (United States)

    Dartois, E.; Augé, B.; Boduch, P.; Brunetto, R.; Chabot, M.; Domaracka, A.; Ding, J. J.; Kamalou, O.; Lv, X. Y.; Rothard, H.; da Silveira, E. F.; Thomas, J. C.

    2015-04-01

    Context. Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. Aims: We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. Methods: We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results: The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions: The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice sputtering rates compete with the UV photodesorption yields reported in the literature. The prevalence of direct cosmic ray sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices. Experiments performed at the Grand Accélérateur National d'Ions Lourds (GANIL) Caen, France. Part of this work has been financed by the French INSU-CNRS programme "Physique et Chimie du Milieu Interstellaire" (PCMI) and the ANR IGLIAS.

  6. Methane excess in Arctic surface water-triggered by sea ice formation and melting.

    Science.gov (United States)

    Damm, E; Rudels, B; Schauer, U; Mau, S; Dieckmann, G

    2015-11-10

    Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas.

  7. Magnetospheric ion sputtering and water ice grain size at Europa

    Science.gov (United States)

    Cassidy, T. A.; Paranicas, C. P.; Shirley, J. H.; Dalton, J. B., III; Teolis, B. D.; Johnson, R. E.; Kamp, L.; Hendrix, A. R.

    2013-03-01

    We present the first calculation of Europa's sputtering (ion erosion) rate as a function of position on Europa's surface. We find a global sputtering rate of 2×1027 H2O s-1, some of which leaves the surface in the form of O2 and H2. The calculated O2 production rate is 1×1026 O2 s-1, H2 production is twice that value. The total sputtering rate (including all species) peaks at the trailing hemisphere apex and decreases to about 1/3rd of the peak value at the leading hemisphere apex. O2 and H2 sputtering, by contrast, is confined almost entirely to the trailing hemisphere. Most sputtering is done by energetic sulfur ions (100s of keV to MeV), but most of the O2 and H2 production is done by cold oxygen ions (temperature ∼ 100 eV, total energy ∼ 500 eV). As a part of the sputtering rate calculation we compared experimental sputtering yields with analytic estimates. We found that the experimental data are well approximated by the expressions of Famá et al. for ions with energies less than 100 keV (Famá, M., Shi, J., Baragiola, R.A., 2008. Sputtering of ice by low-energy ions. Surf. Sci. 602, 156-161), while the expressions from Johnson et al. fit the data best at higher energies (Johnson, R.E., Burger, M.H., Cassidy, T.A., Leblanc, F., Marconi, M., Smyth, W.H., 2009. Composition and Detection of Europa's Sputter-Induced Atmosphere, in: Pappalardo, R.T., McKinnon, W.B., Khurana, K.K. (Eds.), Europa. University of Arizona Press, Tucson.). We compare the calculated sputtering rate with estimates of water ice regolith grain size as estimated from Galileo Near-Infrared Mapping Spectrometer (NIMS) data, and find that they are strongly correlated as previously suggested by Clark et al. (Clark, R.N., Fanale, F.P., Zent, A.P., 1983. Frost grain size metamorphism: Implications for remote sensing of planetary surfaces. Icarus 56, 233-245.). The mechanism responsible for the sputtering rate/grain size link is uncertain. We also report a surface composition estimate using

  8. DISCOVERY OF CRYSTALLIZED WATER ICE IN A SILHOUETTE DISK IN THE M43 REGION

    Energy Technology Data Exchange (ETDEWEB)

    Terada, Hiroshi [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Tokunaga, Alan T., E-mail: terada@subaru.naoj.org [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu 96822 (United States)

    2012-07-01

    We present the 1.9-4.2 {mu}m spectra of the five bright (L {<=} 11.2) young stars associated with silhouette disks with a moderate to high inclination angle of 39 Degree-Sign -80 Degree-Sign in the M42 and M43 regions. The water ice absorption is seen toward d121-1925 and d216-0939, while the spectra of d182-316, d183-405, and d218-354 show no water ice feature around 3.1 {mu}m within the detection limits. By comparing the water ice features toward nearby stars, we find that the water ice absorption toward d121-1925 and d216-0939 most likely originates from the foreground material and the surrounding disk, respectively. The angle of the disk inclination is found to be mainly responsible for the difference of the optical depth of the water ice among the five young stars. Our results suggest that there is a critical inclination angle between 65 Degree-Sign and 75 Degree-Sign for the circumstellar disk where the water ice absorption becomes strong. The average density at the disk surface of d216-0939 was found to be 6.38 Multiplication-Sign 10{sup -18} g cm{sup -3}. The water ice absorption band in the d216-0939 disk is remarkable in that the maximum optical depth of the water ice band is at a longer wavelength than detected before. It indicates that the primary carrier of the feature is purely crystallized water ice at the surface of the d216-0939 disk with characteristic size of {approx}0.8 {mu}m, which suggests grain growth. This is the first direct detection of purely crystallized water ice in a silhouette disk.

  9. Molecular multipole moments of water molecules in ice Ih

    International Nuclear Information System (INIS)

    Batista, E.R.; Xantheas, S.S.; Jonsson, H.

    1998-01-01

    We have used an induction model including dipole, dipole endash quadrupole, quadrupole endash quadrupole polarizability and first hyperpolarizability as well as fixed octopole and hexadecapole moments to study the electric field in ice. The self-consistent induction calculations gave an average total dipole moment of 3.09 D, a 67% increase over the dipole moment of an isolated water molecule. A previous, more approximate induction model study by Coulson and Eisenberg [Proc. R. Soc. Lond. A 291, 445 (1966)] suggested a significantly smaller average value of 2.6 D. This value has been used extensively in recent years as a reference point in the development of various polarizable interaction potentials for water as well as for assessment of the convergence of water cluster properties to those of bulk. The reason for this difference is not due to approximations made in the computational scheme of Coulson and Eisenberg but rather due to the use of less accurate values for the molecular multipoles in these earlier calculations. copyright 1998 American Institute of Physics

  10. Observations of the PCB distribution within and in-between ice, snow, ice-rafted debris, ice-interstitial water, and seawater in the Barents Sea marginal ice zone and the North Pole area.

    Science.gov (United States)

    Gustafsson, O; Andersson, P; Axelman, J; Bucheli, T D; Kömp, P; McLachlan, M S; Sobek, A; Thörngren, J-O

    2005-04-15

    To evaluate the two hypotheses of locally elevated exposure of persistent organic pollutants (POPs) in ice-associated microenvironments and ice as a key carrier for long-range transport of POPs to the Arctic marginal ice zone (MIZ), dissolved and particulate polychlorinated biphenyls (PCBs) were analyzed in ice, snow, ice-interstitial water (IIW), seawater in the melt layer underlying the ice, and in ice-rafted sediment (IRS) from the Barents Sea MIZ to the high Arctic in the summer of 2001. Ultra-clean sampling equipment and protocols were specially developed for this expedition, including construction of a permanent clean room facility and a stainless steel seawater intake system on the I/B ODEN as well as two mobile 370 l ice-melting systems. Similar concentrations were found in several ice-associated compartments. For instance, the concentration of one of the most abundant congeners, PCB 52, was typically on the order of 0.1-0.3 pg l(-1) in the dissolved (melted) phase of the ice, snow, IIW, and underlying seawater while its particulate organic-carbon (POC) normalized concentrations were around 1-3 ng gPOC(-1) in the ice, snow, IIW, and IRS. The solid-water distribution of PCBs in ice was well correlated with and predictable from K(ow) (ice log K(oc)-log K(ow) regressions: p<0.05, r2=0.78-0.98, n=9), indicating near-equilibrium partitioning of PCBs within each local ice system. These results do generally not evidence the existence of physical microenvironments with locally elevated POP exposures. However, there were some indications that the ice-associated system had harbored local environments with higher exposure levels earlier/before the melting/vegetative season, as a few samples had PCB concentrations elevated by factors of 5-10 relative to the typical values, and the elevated levels were predominantly found at the station where melting had putatively progressed the least. The very low PCB concentrations and absence of any significant concentration

  11. Observations of the PCB distribution within and in-between ice, snow, ice-rafted debris, ice-interstitial water, and seawater in the Barents Sea marginal ice zone and the North Pole area

    International Nuclear Information System (INIS)

    Gustafsson, Oe.; Andersson, P.; Axelman, J.; Bucheli, T.D.; Koemp, P.; McLachlan, M.S.; Sobek, A.; Thoerngren, J.-O.

    2005-01-01

    To evaluate the two hypotheses of locally elevated exposure of persistent organic pollutants (POPs) in ice-associated microenvironments and ice as a key carrier for long-range transport of POPs to the Arctic marginal ice zone (MIZ), dissolved and particulate polychlorinated biphenyls (PCBs) were analyzed in ice, snow, ice-interstitial water (IIW), seawater in the melt layer underlying the ice, and in ice-rafted sediment (IRS) from the Barents Sea MIZ to the high Arctic in the summer of 2001. Ultra-clean sampling equipment and protocols were specially developed for this expedition, including construction of a permanent clean room facility and a stainless steel seawater intake system on the I/B ODEN as well as two mobile 370 l ice-melting systems. Similar concentrations were found in several ice-associated compartments. For instance, the concentration of one of the most abundant congeners, PCB 52, was typically on the order of 0.1-0.3 pg l -1 in the dissolved (melted) phase of the ice, snow, IIW, and underlying seawater while its particulate organic-carbon (POC) normalized concentrations were around 1-3 ng gPOC -1 in the ice, snow, IIW, and IRS. The solid-water distribution of PCBs in ice was well correlated with and predictable from K ow (ice log K oc -log K ow regressions: p 2 =0.78-0.98, n=9), indicating near-equilibrium partitioning of PCBs within each local ice system. These results do generally not evidence the existence of physical microenvironments with locally elevated POP exposures. However, there were some indications that the ice-associated system had harbored local environments with higher exposure levels earlier/before the melting/vegetative season, as a few samples had PCB concentrations elevated by factors of 5-10 relative to the typical values, and the elevated levels were predominantly found at the station where melting had putatively progressed the least. The very low PCB concentrations and absence of any significant concentration gradients, both

  12. Ice Water Classification Using Statistical Distribution Based Conditional Random Fields in RADARSAT-2 Dual Polarization Imagery

    Science.gov (United States)

    Zhang, Y.; Li, F.; Zhang, S.; Hao, W.; Zhu, T.; Yuan, L.; Xiao, F.

    2017-09-01

    In this paper, Statistical Distribution based Conditional Random Fields (STA-CRF) algorithm is exploited for improving marginal ice-water classification. Pixel level ice concentration is presented as the comparison of methods based on CRF. Furthermore, in order to explore the effective statistical distribution model to be integrated into STA-CRF, five statistical distribution models are investigated. The STA-CRF methods are tested on 2 scenes around Prydz Bay and Adélie Depression, where contain a variety of ice types during melt season. Experimental results indicate that the proposed method can resolve sea ice edge well in Marginal Ice Zone (MIZ) and show a robust distinction of ice and water.

  13. The study of fresh-water lake ice using multiplexed imaging radar

    Science.gov (United States)

    Leonard, Bryan M.; Larson, R.W.

    1975-01-01

    The study of ice in the upper Great Lakes, both from the operational and the scientific points of view, is receiving continued attention. Quantitative and qualitative field work is being conducted to provide the needed background for accurate interpretation of remotely sensed data. The data under discussion in this paper were obtained by a side-looking multiplexed airborne radar (SLAR) supplemented with ground-truth data.Because of its ability to penetrate adverse weather, radar is an especially important instrument for monitoring ice in the upper Great Lakes. It has previously been shown that imaging radars can provide maps of ice cover in these areas. However, questions concerning both the nature of the surfaces reflecting radar energy and the interpretation of the radar imagery continually arise.Our analysis of ice in Whitefish Bay (Lake Superior) indicates that the combination of the ice/water interlace and the ice/air interface is the major contributor to the radar backscatter as seen on the imagery At these frequencies the ice has a very low relative dielectric permittivity (types studied include newly formed black ice, pancake ice, and frozen and consolidated pack and brash ice.Although ice thickness cannot be measured directly from the received signals, it is suspected that by combining the information pertaining to radar backscatter with data on the meteorological and sea-state history of the area, together with some basic ground truth, better estimates of the ice thickness may be provided. In addition, certain ice features (e.g. ridges, ice-foot formation, areas of brash ice) may be identified with reasonable confidence. There is a continued need for additional ground work to verify the validity of imaging radars for these types of interpretations.

  14. Study on heat transfer performance of water-borne and oily graphene coatings using anti-/de-icing component

    Science.gov (United States)

    Chen, Long; Zhang, Yidu; Wu, Qiong; Jie, Zhang

    2018-02-01

    A graphene coating anti-/de-icing experiment was proposed by employing water-borne and oily graphene coatings on the composite material anti-/de-icing component. Considering the characteristics of helicopter rotor sensitivity to icing, a new graphene coating enhancing thermal conductivity of anti-/de-icing component was proposed. The anti-/de-icing experiment was conducted to validate the effectiveness of graphene coating. The results of the experiment show that the graphene coatings play a prominent role in controlling the heat transfer of anti-/de-icing component. The anti-/de-icing effect of oily graphene coating is superior to water-borne graphene.

  15. Ice haze, snow, and the Mars water cycle

    Science.gov (United States)

    Kahn, Ralph

    1990-01-01

    Light curves and extinction profiles derived from Martian limb observations are used to constrain the atmospheric temperature structure in regions of the atmosphere with thin haze and to analyze the haze particle properties and atmospheric eddy mixing. Temperature between 170 and 190 K are obtained for three cases at levels in the atmosphere ranging from 20 to 50 km. Eddy diffusion coefficients around 100,000 sq cm/s, typical of a nonconvecting atmosphere, are derived in the haze regions at times when the atmosphere is relatively clear of dust. This parameter apparently changes by more than three orders of magnitude with season and local conditions. The derived particle size parameter varies systematically by more than an order of magnitude with condensation level, in such a way that the characteristic fall time is always about one Martian day. Ice hazes provide a mechanism for scavenging water vapor in the thin Mars atmosphere and may play a key role in the seasonal cycle of water on Mars.

  16. ON THE FORMATION OF INTERSTELLAR WATER ICE: CONSTRAINTS FROM A SEARCH FOR HYDROGEN PEROXIDE ICE IN MOLECULAR CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R. G.; Wright, C. M.; Robinson, G. [School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600 (Australia); Charnley, S. B. [Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Pendleton, Y. J. [NASA Lunar Science Institute, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Maldoni, M. M., E-mail: r.smith@adfa.edu.au, E-mail: c.wright@adfa.edu.au, E-mail: g.robinson@adfa.edu.au, E-mail: Steven.B.Charnley@nasa.gov, E-mail: yvonne.pendleton@nasa.gov [Geoscience Australia, Canberra, ACT 2601 (Australia)

    2011-12-20

    Recent surface chemistry experiments have shown that the hydrogenation of molecular oxygen on interstellar dust grains is a plausible formation mechanism, via hydrogen peroxide (H{sub 2}O{sub 2}), for the production of water (H{sub 2}O) ice mantles in the dense interstellar medium. Theoretical chemistry models also predict the formation of a significant abundance of H{sub 2}O{sub 2} ice in grain mantles by this route. At their upper limits, the predicted and experimental abundances are sufficiently high that H{sub 2}O{sub 2} should be detectable in molecular cloud ice spectra. To investigate this further, laboratory spectra have been obtained for H{sub 2}O{sub 2}/H{sub 2}O ice films between 2.5 and 200 {mu}m, from 10 to 180 K, containing 3%, 30%, and 97% H{sub 2}O{sub 2} ice. Integrated absorbances for all the absorption features in low-temperature H{sub 2}O{sub 2} ice have been derived from these spectra. For identifying H{sub 2}O{sub 2} ice, the key results are the presence of unique features near 3.5, 7.0, and 11.3 {mu}m. Comparing the laboratory spectra with the spectra of a group of 24 protostars and field stars, all of which have strong H{sub 2}O ice absorption bands, no absorption features are found that can definitely be identified with H{sub 2}O{sub 2} ice. In the absence of definite H{sub 2}O{sub 2} features, the H{sub 2}O{sub 2} abundance is constrained by its possible contribution to the weak absorption feature near 3.47 {mu}m found on the long-wavelength wing of the 3 {mu}m H{sub 2}O ice band. This gives an average upper limit for H{sub 2}O{sub 2}, as a percentage of H{sub 2}O, of 9% {+-} 4%. This is a strong constraint on parameters for surface chemistry experiments and dense cloud chemistry models.

  17. VOLATILE TRANSPORT INSIDE SUPER-EARTHS BY ENTRAPMENT IN THE WATER-ICE MATRIX

    Energy Technology Data Exchange (ETDEWEB)

    Levi, A.; Podolak, M. [Department of Geophysics and Planetary Science, Tel Aviv University, Tel Aviv 69978 (Israel); Sasselov, D., E-mail: amitlevi.planetphys@gmail.com [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-05-20

    Whether volatiles can be entrapped in a background matrix composing planetary envelopes and be dragged via convection to the surface is a key question in understanding atmospheric fluxes, cycles, and composition. In this paper, we consider super-Earths with an extensive water mantle (i.e., water planets), and the possibility of entrapment of methane in their extensive water-ice envelopes. We adopt the theory developed by van der Waals and Platteeuw for modeling solid solutions, often used for modeling clathrate hydrates, and modify it in order to estimate the thermodynamic stability field of a new phase called methane filled ice Ih. We find that in comparison to water ice VII the filled ice Ih structure may be stable not only at the high pressures but also at the high temperatures expected at the core-water mantle transition boundary of water planets.

  18. ICE911 Research: Floating Safe Inert Materials to Preserve Ice and Conserve Water in Order to Mitigate Climate Change Impacts

    Science.gov (United States)

    Field, L. A.; Manzara, A.; Chetty, S.; Venkatesh, S.; Scholtz, A.

    2015-12-01

    Ice911 Research has conducted years of field testing to develop and test localized reversible engineering techniques to mitigate the negative impacts of polar ice melt. The technology uses environmentally safe materials to reflect energy in carefully selected, limited areas from summertime polar sun. The technology is now being adapted to help with California's drought. We have tested the albedo modification technique on a small scale over seven Winter/Spring seasons at sites including California's Sierra Nevada Mountains, a Canadian lake, and a small artificial pond in Minnesota about 100 ft in diameter and 6 ft deep at the center, using various materials and an evolving array of instrumentation. On the pond in Minnesota, this year's test results for ice preservation, using hollow glass spheres deployed over our largest test areas yet, showed that glass bubbles can provide an effective material for increasing albedo, significantly reducing the melting rate of ice. This year Ice911 also undertook its first small Arctic field test in Barrow, Alaska on a lake in Barrow's BEO area, and results are still coming in. The technology that Ice911 has been developing for ice preservation has also been shown to keep small test areas of water cooler, in various small-scale tests spanning years. We believe that with some adaptations of the technology, the materials can be applied to reservoirs and lakes to help stretch these precious resources further in California's ongoing drought. There are several distinct advantages for this method over alternatives such as large reverse osmosis projects or building new reservoirs, which could possibly allow a drought-stricken state to build fewer of these more-costly alternatives. First, applying an ecologically benign surface treatment of Ice911's materials can be accomplished within a season, at a lower cost, with far less secondary environmental impact, than such capital-and-time-intensive infrastructure projects. Second, keeping

  19. Chlorine-containing salts as water ice nucleating particles on Mars

    Science.gov (United States)

    Santiago-Materese, D. L.; Iraci, L. T.; Clapham, M. E.; Chuang, P. Y.

    2018-03-01

    Water ice cloud formation on Mars largely is expected to occur on the most efficient ice nucleating particle available. Salts have been observed on the Martian surface and have been known to facilitate water cloud formation on Earth. We examined heterogeneous ice nucleation onto sodium chloride and sodium perchlorate substrates under Martian atmospheric conditions, in the range of 150 to 180 K and 10-7 to 10-5 Torr water partial pressure. Sub-155 K data for the critical saturation ratio (Scrit) suggests an exponential model best describes the temperature-dependence of nucleation onset of water ice for all substrates tested. While sodium chloride does not facilitate water ice nucleation more easily than bare silicon, sodium perchlorate does support depositional nucleation at lower saturation levels than other substrates shown and is comparable to smectite-rich clay in its ability to support cloud initiation. Perchlorates could nucleate water ice at partial pressures up to 40% lower than other substrates examined to date under Martian atmospheric conditions. These findings suggest air masses on Mars containing uplifted salts such as perchlorates could form water ice clouds at lower saturation ratios than in air masses absent similar particles.

  20. Circulation and water properties in the landfast ice zone of the Alaskan Beaufort Sea

    Science.gov (United States)

    Weingartner, Thomas J.; Danielson, Seth L.; Potter, Rachel A.; Trefry, John H.; Mahoney, Andy; Savoie, Mark; Irvine, Cayman; Sousa, Leandra

    2017-09-01

    Moorings, hydrography, satellite-tracked drifters, and high-frequency radar data describe the annual cycle in circulation and water properties in the landfast ice zone (LIZ) of the Alaskan Beaufort Sea. Three seasons, whose duration and characteristics are controlled by landfast ice formation and ablation, define the LIZ: ;winter;, ;break-up;, and ;open-water;. Winter begins in October with ice formation and ends in June when rivers commence discharging. Winter LIZ ice velocities are zero, under-ice currents are weak ( 5 cm s-1), and poorly correlated with winds and local sea level. The along-shore momentum balance is between along-shore pressure gradients and bottom and ice-ocean friction. Currents at the landfast ice-edge are swift ( 35 cm s-1), wind-driven, with large horizontal shears, and potentially unstable. Weak cross-shore velocities ( 1 cm s-1) imply limited exchanges between the LIZ and the outer shelf in winter. The month-long break-up season (June) begins with the spring freshet and concludes when landfast ice detaches from the bottom. Cross-shore currents increase, and the LIZ hosts shallow ( 2 m), strongly-stratified, buoyant and sediment-laden, under-ice river plumes that overlie a sharp, 1 m thick, pycnocline across which salinity increases by 30. The plume salt balance is between entrainment and cross-shore advection. Break-up is followed by the 3-month long open-water season when currents are swift (≥20 cm s-1) and predominantly wind-driven. Winter water properties are initialized by fall advection and evolve slowly due to salt rejection from ice. Fall waters and ice within the LIZ derive from local rivers, the Mackenzie and/or Chukchi shelves, and the Arctic basin.

  1. Hydrodynamic analysis and simulation of a flow cell ammonia electrolyzer

    International Nuclear Information System (INIS)

    Diaz, Luis A.; Botte, Gerardine G.

    2015-01-01

    Highlights: • NH_3 electrooxidation mechanism was validated in a bench scale electrolyzer. • All kinetic parameters for NH_3 electro-oxidation were calculated and verified. • Hydrodynamic behavior of the NH_3 electrolyzer was properly described as a CSTR. • CSTR model was successfully applied to simulate a flow ammonia electrolyzer. - Abstract: The hydrodynamic analysis and simulation of a non-ideal single pass flow cell alkaline ammonia electrolyzer was performed after the scale-up of a well-characterized deposited polycrystalline Pt on Ni anode. The hydrodynamic analysis was performed using the residence time distribution (RTD) test. The results of the hydrodynamic investigation provide additional insights for the kinetic analysis of the ammonia electrooxidation reaction on polycrystalline Pt electrocatalysts -which are typically obtained under controlled flow regime, e.g., rotating disk electrode- by including the flow non-uniformity present in the electrolyzer. Based on the RTD function, the ammonia electrolyzer performance was simulated as a non-steady stirred tank reactor (CSTR) and the unknown kinetic parameters were obtained by fitting the simulation results with an experimental current profile, obtaining an adequate prediction of the ammonia conversion. This simplified approach for the simulation of the ammonia electrolyzer could be implemented in process simulation packages and could be used for the design and scale-up of the process for hydrogen production and wastewater remediation.

  2. Direct calculation of ice homogeneous nucleation rate for a molecular model of water

    Science.gov (United States)

    Haji-Akbari, Amir; Debenedetti, Pablo G.

    2015-01-01

    Ice formation is ubiquitous in nature, with important consequences in a variety of environments, including biological cells, soil, aircraft, transportation infrastructure, and atmospheric clouds. However, its intrinsic kinetics and microscopic mechanism are difficult to discern with current experiments. Molecular simulations of ice nucleation are also challenging, and direct rate calculations have only been performed for coarse-grained models of water. For molecular models, only indirect estimates have been obtained, e.g., by assuming the validity of classical nucleation theory. We use a path sampling approach to perform, to our knowledge, the first direct rate calculation of homogeneous nucleation of ice in a molecular model of water. We use TIP4P/Ice, the most accurate among existing molecular models for studying ice polymorphs. By using a novel topological approach to distinguish different polymorphs, we are able to identify a freezing mechanism that involves a competition between cubic and hexagonal ice in the early stages of nucleation. In this competition, the cubic polymorph takes over because the addition of new topological structural motifs consistent with cubic ice leads to the formation of more compact crystallites. This is not true for topological hexagonal motifs, which give rise to elongated crystallites that are not able to grow. This leads to transition states that are rich in cubic ice, and not the thermodynamically stable hexagonal polymorph. This mechanism provides a molecular explanation for the earlier experimental and computational observations of the preference for cubic ice in the literature. PMID:26240318

  3. The role of water ice clouds in the Martian hydrologic cycle

    Science.gov (United States)

    James, Philip B.

    1990-01-01

    A one-dimensional model for the seasonal cycle of water on Mars has been used to investigate the direction of the net annual transport of water on the planet and to study the possible role of water ice clouds, which are included as an independent phase in addition to ground ice and water vapor, in the cycle. The calculated seasonal and spatial patterns of occurrence of water ice clouds are qualitatively similar to the observed polar hoods, suggesting that these polar clouds are, in fact, an important component of water cycle. A residual dry ice in the south acts as a cold trap which, in the absence of sources other than the caps, will ultimately attract the water ice from the north cap; however, in the presence of a source of water in northern midlatitudes during spring, it is possible that the observed distribution of vapor and ice can be in a steady state even if a residual CO2 cap is a permanent feature of the system.

  4. The role of ice dynamics in shaping vegetation in flowing waters.

    Science.gov (United States)

    Lind, Lovisa; Nilsson, Christer; Polvi, Lina E; Weber, Christine

    2014-11-01

    Ice dynamics is an important factor affecting vegetation in high-altitude and high-latitude streams and rivers. During the last few decades, knowledge about ice in streams and rivers has increased significantly and a respectable body of literature is now available. Here we review the literature on how ice dynamics influence riparian and aquatic vegetation. Traditionally, plant ecologists have focused their studies on the summer period, largely ignoring the fact that processes during winter also impact vegetation dynamics. For example, the freeze-up period in early winter may result in extensive formation of underwater ice that can restructure the channel, obstruct flow, and cause flooding and thus formation of more ice. In midwinter, slow-flowing reaches develop a surface-ice cover that accumulates snow, protecting habitats under the ice from formation of underwater ice but also reducing underwater light, thus suppressing photosynthesis. Towards the end of winter, ice breaks up and moves downstream. During this transport, ice floes can jam up and cause floods and major erosion. The magnitudes of the floods and their erosive power mainly depend on the size of the watercourse, also resulting in different degrees of disturbance to the vegetation. Vegetation responds both physically and physiologically to ice dynamics. Physical action involves the erosive force of moving ice and damage caused by ground frost, whereas physiological effects - mostly cell damage - happen as a result of plants freezing into the ice. On a community level, large magnitudes of ice dynamics seem to favour species richness, but can be detrimental for individual plants. Human impacts, such as flow regulation, channelisation, agriculturalisation and water pollution have modified ice dynamics; further changes are expected as a result of current and predicted future climate change. Human impacts and climate change can both favour and disfavour riverine vegetation dynamics. Restoration of streams

  5. A simulation study of homogeneous ice nucleation in supercooled salty water

    Science.gov (United States)

    Soria, Guiomar D.; Espinosa, Jorge R.; Ramirez, Jorge; Valeriani, Chantal; Vega, Carlos; Sanz, Eduardo

    2018-06-01

    We use computer simulations to investigate the effect of salt on homogeneous ice nucleation. The melting point of the employed solution model was obtained both by direct coexistence simulations and by thermodynamic integration from previous calculations of the water chemical potential. Using a seeding approach, in which we simulate ice seeds embedded in a supercooled aqueous solution, we compute the nucleation rate as a function of temperature for a 1.85 NaCl mol per water kilogram solution at 1 bar. To improve the accuracy and reliability of our calculations, we combine seeding with the direct computation of the ice-solution interfacial free energy at coexistence using the Mold Integration method. We compare the results with previous simulation work on pure water to understand the effect caused by the solute. The model captures the experimental trend that the nucleation rate at a given supercooling decreases when adding salt. Despite the fact that the thermodynamic driving force for ice nucleation is higher for salty water for a given supercooling, the nucleation rate slows down with salt due to a significant increase of the ice-fluid interfacial free energy. The salty water model predicts an ice nucleation rate that is in good agreement with experimental measurements, bringing confidence in the predictive ability of the model. We expect that the combination of state-of-the-art simulation methods here employed to study ice nucleation from solution will be of much use in forthcoming numerical investigations of crystallization in mixtures.

  6. Perennial water stratification and the role of freshwater in the mass balance of Arctic ice shelves and multiyear landfast sea ice

    International Nuclear Information System (INIS)

    Jeffries, M.O.

    1991-01-01

    A number of the ice shelves of northern Ellesmere Island in the Canadian High Arctic owe their origin to multiyear landfast sea ice (MLSI) growth during the post-Hypsithermal cooling ca. 3,000-4,000 BP. Since they grew in response to an arctic-wide climatic deterioration and contain evidence of occasional post-4,000 BP climatic ameliorations, they may be expected to be sensitive to future global climate changes manifested in the High Arctic. The purpose of this paper is to examine ice-ocean interactions and feedbacks, and the response of the ice shelves and the MLSI to the improved summer climate of the last ca. 100 years, and implications for the future. There is good evidence that there has been a negative surface mass balance since the turn of the century. Mass balance measurements on the Ward Hunt Ice Shelf between 1966 and 1985 indicate a total ice loss of 1.371 m at a mean annual rate of 68.5 mm. The interannual pattern of accumulation and ablation and the long-term losses on the ice shelf are similar to other Canadian High Arctic glacier mass balance records. It is evident from water and ice core records of salinity, δ 18 0 and tritium, that perennial water stratification is common below and behind the ice shelves and MLSI. The coastal waters are highly stratified, with anything from 0.5 m to 41.0 m of freshwater interposed between the overlying ice and underlying seawater. The primary source of the freshwater is summer run-off of snow-meltwater from the adjacent land and from the ice itself. There is minimal mixing between the influent freshwater and seawater, and the freshwater is either dammed behind the ice shelves and the MLSI, with subsequent under-ice freshwater outflows, or pooled in under-ice depressions

  7. Heterogeneous ice nucleation in aqueous solutions: the role of water activity.

    Science.gov (United States)

    Zobrist, B; Marcolli, C; Peter, T; Koop, T

    2008-05-01

    Heterogeneous ice nucleation experiments have been performed with four different ice nuclei (IN), namely nonadecanol, silica, silver iodide and Arizona test dust. All IN are either immersed in the droplets or located at the droplets surface. The IN were exposed to various aqueous solutions, which consist of (NH4)2SO4, H2SO4, MgCl2, NaCl, LiCl, Ca(NO3)2, K2CO3, CH3COONa, ethylene glycol, glycerol, malonic acid, PEG300 or a NaCl/malonic acid mixture. Freezing was studied using a differential scanning calorimeter and a cold finger cell. The results show that the heterogeneous ice freezing temperatures decrease with increasing solute concentration; however, the magnitude of this effect is solute dependent. In contrast, when the results are analyzed in terms of the solution water activity a very consistent behavior emerges: heterogeneous ice nucleation temperatures for all four IN converge each onto a single line, irrespective of the nature of the solute. We find that a constant offset with respect to the ice melting point curve, Deltaaw,het, can describe the observed freezing temperatures for each IN. Such a behavior is well-known for homogeneous ice nucleation from supercooled liquid droplets and has led to the development of water-activity-based ice nucleation theory. The large variety of investigated solutes together with different general types of ice nuclei studied (monolayers, ionic crystals, covalently bound network-forming compounds, and a mixture of chemically different crystallites) underlines the general applicability of water-activity-based ice nucleation theory also for heterogeneous ice nucleation in the immersion mode. Finally, the ice nucleation efficiencies of the various IN, as well as the atmospheric implication of the developed parametrization are discussed.

  8. Triple Isotope Water Measurements of Lake Untersee Ice using Off-Axis ICOS

    Science.gov (United States)

    Berman, E. S.; Huang, Y. W.; Andersen, D. T.; Gupta, M.; McKay, C. P.

    2015-12-01

    Lake Untersee (71.348°S, 13.458°E) is the largest surface freshwater lake in the interior of the Gruber Mountains of central Queen Maud Land in East Antarctica. The lake is permanently covered with ice, is partly bounded by glacier ice and has a mean annual air temperature of -10°C. In contrast to other Antarctic lakes the dominating physical process controlling ice-cover dynamics is low summer temperatures and high wind speeds resulting in sublimation rather than melting as the main mass-loss process. The ice-cover of the lake is composed of lake-water ice formed during freeze-up and rafted glacial ice derived from the Anuchin Glacier. The mix of these two fractions impacts the energy balance of the lake, which directly affects ice-cover thickness. Ice-cover is important if one is to understand the physical, chemical, and biological linkages within these unique, physically driven ecosystems. We have analyzed δ2H, δ18O, and δ17O from samples of lake and glacier ice collected at Lake Untersee in Dec 2014. Using these data we seek to answer two specific questions: Are we able to determine the origin and history of the lake ice, discriminating between rafted glacial ice and lake water? Can isotopic gradients in the surface ice indicate the ablation (sublimation) rate of the surface ice? The triple isotope water analyzer developed by Los Gatos Research (LGR 912-0032) uses LGR's patented Off-Axis ICOS (Integrated Cavity Output Spectroscopy) technology and incorporates proprietary internal thermal control for high sensitivity and optimal instrument stability. This analyzer measures δ2H, δ18O, and δ17O from water, as well as the calculated d-excess and 17O-excess. The laboratory precision in high performance mode for both δ17O and δ18O is 0.03 ‰, and for δ2H is 0.2 ‰. Methodology and isotope data from Lake Untersee samples are presented. Figure: Ice samples were collected across Lake Untersee from both glacial and lake ice regions for this study.

  9. Great Lakes Daily Ice Observations at NOAA Water Level Gauge Sites, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains daily visual ice observations taken yearly from 1 November to 30 April at NOAA/National Ocean Service water level gauge sites in the Great...

  10. Great Lakes Daily Ice Observations at NOAA Water Level Gauge Sites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains daily visual ice observations taken yearly from 1 November to 30 April at NOAA/National Ocean Service water level gauge sites in the Great...

  11. Petroleum activity in ice covered waters - development and operation phase. Focus of eventual consequential explanation

    International Nuclear Information System (INIS)

    Thomassen, J.; Andresen, K.H.; Moe, K.A.

    1996-06-01

    This report from a seminar relates to the petroleum activities in the Barentshavet north. The focal point was to put on petroleum activities in ice covered waters covering the drilling and operation phase, to identify discharges from various technical solutions, and to classify possible research requirements when mapping the impacts of such components. In addition to this approach, the seminar also focused on other factors regarding drilling and production activities in ice covered waters. 3 refs., 13 figs., 25 tabs

  12. First Detection of Water Ice and Organics on an Asteroid: A Possible Link to the Origin of Earth's Water

    Science.gov (United States)

    Hargrove, Kelsey D.; Campins, H.; Pinilla-Alonso, N.; Howell, E. S.; Kelley, M. S.; Licandro, J.; Mothédiniz, T.; Fernández, Y.; Ziffer, J.

    2010-05-01

    We report the detection of water ice and organics on the surface of asteroid 24 Themis. Our rotationally-resolved infrared (2-4 µm) spectra of this asteroid indicate that the ice and organics are widespread on its surface. The spectral difference with other asteroids observed in the same manner, makes 24 Themis unique so far. Our identification of water ice and organic compounds on this asteroid agrees with independent results (Rivkin and Emery 2010). At first glance, the presence of any surface ice on 24 Themis, particularly over a significant fraction of its surface, is puzzling because of the instability for exposed water ice at Themis's heliocentric distance ( 3.2 AU). Nevertheless, there are several possible sources for this unstable ice and identifying them is likely to be diagnostic of other processes on primitive asteroids. The presence of water ice on 24 Themis supports the idea that ice sublimation drives the cometary activity in two small members of the Themis dynamical family, labeled "Main Belt comets” by Hsieh and Jewitt (2006). It also helps to address other relevant questions, such as, how abundant is water ice in the outer asteroid belt and where was the "snow” line when the solar system formed? The answers to these questions could transform current views of primitive asteroids, delivery of water and organic molecules to Earth, and models of Solar System formation. This research was published in the April 29, 2010 issue of the journal Nature. Hargrove and Campins are visiting astronomers at the Infrared Telescope Facility (IRTF), which is operated by the University of Hawaii under Cooperative Agreement no. NCC 5-538 with the National Aeronautics and Space Administration

  13. Photolytic degradation of methyl-parathion and fenitrothion in ice and water: Implications for cold environments

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Jan [Lancaster Environment Centre, Centre for Chemicals Management, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Kurkova, Romana; Klanova, Jana [RECETOX, Faculty of Science, Masaryk University, Kamenice 3, 625 00 Brno (Czech Republic); Klan, Petr, E-mail: klan@sci.muni.c [Dept of Chemistry, Faculty of Science, Masaryk University, Kamenice 5/A8, 625 00 Brno (Czech Republic); Halsall, Crispin J., E-mail: c.halsall@lancaster.ac.u [Lancaster Environment Centre, Centre for Chemicals Management, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

    2009-12-15

    Here we investigate the photodegradation of structurally similar organophosphorus pesticides; methyl-parathion and fenitrothion in water (20 deg. C) and ice (-15 deg. C) under environmentally-relevant conditions with the aim of comparing these laboratory findings to limited field observations. Both compounds were found to be photolyzed more efficiently in ice than in aqueous solutions, with quantum yields of degradation being higher in ice than in water (fenitrothion > methyl-parathion). This rather surprising observation was attributed to the concentration effect caused by freezing the aqueous solutions. The major phototransformation products included the corresponding oxons (methyl-paraoxon and fenitroxon) and the nitrophenols (3-methyl-nitrophenol and nitrophenol) in both irradiated water and ice samples. The presence of oxons in ice following irradiation, demonstrates an additional formation mechanism of these toxicologically relevant compounds in cold environments, although further photodegradation of oxons in ice indicates that photochemistry of OPs might be an environmentally important sink in cold environments. - Photodegradation of methyl-parathion and fenitrothion in water and ice under environmentally-relevant conditions is described.

  14. Bacterial activity in sea ice and open water of the Weddell Sea, Antarctica: A microautoradiographic study.

    Science.gov (United States)

    Grossmann, S

    1994-07-01

    Metabolic activity of bacteria was investigated in open water, newly forming sea ice, and successive stages of pack ice in the Weddell Sea. Microautoradiography, using [(3)H]leucine as substrate, was compared with incorporation rates of [(3)H]leucine into proteins. Relation of [(3)H]leucine incorporation to the biomass of active bacteria provides information about changes of specific metabolic activity of cells. During a phytoplankton bloom in an ice-free, stratified water column, total numbers of bacteria in the euphotic zone averaged 2.3 × 10(5) ml(-1), but only about 13% showed activity via leucine uptake. Growth rate of the active bacteria was estimated as 0.3-0.4 days(-1). Total cell concentration of bacteria in 400 m depth was 6.6 × 10(4) ml(-1). Nearly 50% of these cells were active, although biomass production and specific growth rate were only about one-tenth that of the surface populations. When sea ice was forming in high concentrations of phytoplankton, bacterial biomass in the newly formed ice was 49.1 ng C ml(-1), exceeding that in open water by about one order of magnitude. Attachment of large bacteria to algal cells seems to cause their enrichment in the new ice, since specific bacterial activity was reduced during ice formation, and enrichment of bacteria was not observed when ice formed at low algal concentration. During growth of pack ice, biomass of bacteria increased within the brine channel system. Specific activity was still reduced at these later stages of ice development, and percentages of active cells were as low as 3-5%. In old, thick pack ice, bacterial activity was high and about 30% of cells were active. However, biomass-specific activity of bacteria remained significantly lower than that in open water. It is concluded that bacterial assemblages different to those of open water developed within the ice and were dominated by bacteria with lower average metabolic activity than those of ice-free water.

  15. Effetively trapping air or lqiud water for anti-icing applications

    Science.gov (United States)

    Wang, Jianjun

    2014-03-01

    Icing on solid surfaces leads to operational difficulties and high maintenance efforts for power networks, aircrafts, ships, ground transportation vehicles and house-hold refrigerators, to name but a few. In extreme cases, icing on surfaces causes disastrous events such as crash of aircrafts and collapse of power networks, which result in severe economic impact and large loss of life. This talk is focused on the fundamentals of the ice formation and adhesion of ice with solid substrates aiming for fighting against icing on solid surfaces. When the supercooling is low, it would be possible to remove supercooled liquid water from the solid surfaces before freezing occurs. To achieve this, we design and constructed surfaces that can trap the air at the subfreezing temperature thus condensed water microdroplets could be spontaneously removed after the coalescence. When the supercooling is high, icing on surfaces occurs spontaniously. In this case, we constructed coatings on which aqueous lubricating layer could be trapped, thus the ice adhesion on the coating is so low that the ice formed atop could be removed by a wind action or its own gravity.

  16. Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

    Science.gov (United States)

    Jones, Elizabeth M.; Bakker, Dorothee C. E.; Venables, Hugh J.; Whitehouse, Michael J.; Korb, Rebecca E.; Watson, Andrew J.

    2010-11-01

    ABSTRACT The effect of sea ice melt on the carbonate chemistry of surface waters in the Weddell-Scotia Confluence, Southern Ocean, was investigated during January 2008. Contrasting concentrations of dissolved inorganic carbon (DIC), total alkalinity (TA) and the fugacity of carbon dioxide (fCO2) were observed in and around the receding sea ice edge. The precipitation of carbonate minerals such as ikaite (CaCO3.6H2O) in sea ice brine has the net effect of decreasing DIC and TA and increasing the fCO2 in the brine. Deficits in DIC up to 12 +/- 3 μmol kg-1 in the marginal ice zone (MIZ) were consistent with the release of DIC-poor brines to surface waters during sea ice melt. Biological utilization of carbon was the dominant processes and accounted for 41 +/- 1 μmol kg-1 of the summer DIC deficit. The data suggest that the combined effects of biological carbon uptake and the precipitation of carbonates created substantial undersaturation in fCO2 of 95 μatm in the MIZ during summer sea ice melt. Further work is required to improve the understanding of ikaite chemistry in Antarctic sea ice and its importance for the sea ice carbon pump.

  17. HOGEN{trademark} proton exchange membrane hydrogen generators: Commercialization of PEM electrolyzers

    Energy Technology Data Exchange (ETDEWEB)

    Smith, W.F.; Molter, T.M. [Proton Energy Systems, Inc., Rocky Hill, CT (United States)

    1997-12-31

    PROTON Energy Systems` new HOGEN series hydrogen generators are Proton Exchange Membrane (PEM) based water electrolyzers designed to generate 300 to 1000 Standard Cubic Feet Per Hour (SCFH) of high purity hydrogen at pressures up to 400 psi without the use of mechanical compressors. This paper will describe technology evolution leading to the HOGEN, identify system design performance parameters and describe the physical packaging and interfaces of HOGEN systems. PEM electrolyzers have served US and UK Navy and NASA needs for many years in a variety of diverse programs including oxygen generators for life support applications. In the late 1970`s these systems were advocated for bulk hydrogen generation through a series of DOE sponsored program activities. During the military buildup of the 1980`s commercial deployment of PEM hydrogen generators was de-emphasized as priority was given to new Navy and NASA PEM electrolysis systems. PROTON Energy Systems was founded in 1996 with the primary corporate mission of commercializing PEM hydrogen generators. These systems are specifically designed and priced to meet the needs of commercial markets and produced through manufacturing processes tailored to these applications. The HOGEN series generators are the first step along the path to full commercial deployment of PEM electrolyzer products for both industrial and consumer uses. The 300/1000 series are sized to meet the needs of the industrial gases market today and provide a design base that can transition to serve the needs of a decentralized hydrogen infrastructure tomorrow.

  18. Martian North Polar Water-Ice Clouds During the Viking Era

    Science.gov (United States)

    Tamppari, L. K.; Bass, D. S.

    2000-01-01

    The Viking Orbiters determined that the surface of Mars' northern residual cap consists of water ice. Observed atmospheric water vapor abundances in the equatorial regions have been related to seasonal exchange between reservoirs such as the polar caps, the regolith and between different phases in the atmosphere. Kahn modeled the physical characteristics of ice hazes seen in Viking Orbiter imaging limb data, hypothesizing that ice hazes provide a method for scavenging water vapor from the atmosphere and accumulating it into ice particles. Given that Jakosky found that these particles had sizes such that fallout times were of order one Martian sol, these water-ice hazes provided a method for returning more water to the regolith than that provided by adsorption alone. These hazes could also explain the rapid hemispheric decrease in atmospheric water in late northern summer as well as the increase during the following early spring. A similar comparison of water vapor abundance versus polar cap brightness has been done for the north polar region. They have shown that water vapor decreases steadily between L(sub s) = 100-150 deg while polar cap albedo increases during the same time frame. As a result, they suggested that late summer water-ice deposition onto the ice cap may be the cause of the cap brightening. This deposition could be due to adsorption directly onto the cap surface or to snowfall. Thus, an examination of north polar waterice clouds could lend insight into the fate of the water vapor during this time period. Additional information is contained in the original extended abstract.

  19. The Effect of Seasonal Variability of Atlantic Water on the Arctic Sea Ice Cover

    Science.gov (United States)

    Ivanov, V. V.; Repina, I. A.

    2018-01-01

    Under the influence of global warming, the sea ice in the Arctic Ocean (AO) is expected to reduce with a transition toward a seasonal ice cover by the end of this century. A comparison of climate-model predictions with measurements shows that the actual rate of ice cover decay in the AO is higher than the predicted one. This paper argues that the rapid shrinking of the Arctic summer ice cover is due to its increased seasonality, while seasonal oscillations of the Atlantic origin water temperature create favorable conditions for the formation of negative anomalies in the ice-cover area in winter. The basis for this hypothesis is the fundamental possibility of the activation of positive feedback provided by a specific feature of the seasonal cycle of the inflowing Atlantic origin water and the peaking of temperature in the Nansen Basin in midwinter. The recently accelerated reduction in the summer ice cover in the AO leads to an increased accumulation of heat in the upper ocean layer during the summer season. The extra heat content of the upper ocean layer favors prerequisite conditions for winter thermohaline convection and the transfer of heat from the Atlantic water (AW) layer to the ice cover. This, in turn, contributes to further ice thinning and a decrease in ice concentration, accelerated melting in summer, and a greater accumulation of heat in the ocean by the end of the following summer. An important role is played by the seasonal variability of the temperature of AW, which forms on the border between the North European and Arctic basins. The phase of seasonal oscillation changes while the AW is moving through the Nansen Basin. As a result, the timing of temperature peak shifts from summer to winter, additionally contributing to enhanced ice melting in winter. The formulated theoretical concept is substantiated by a simplified mathematical model and comparison with observations.

  20. Water Ice Clouds and Dust in the Martian Atmosphere Observed by Mars Climate Sounder

    Science.gov (United States)

    Benson, Jennifer L.; Kass, David; Heavens, Nicholas; Kleinbohl, Armin

    2011-01-01

    The water ice clouds are primarily controlled by the temperature structure and form at the water condensation level. Clouds in all regions presented show day/night differences. Cloud altitude varies between night and day in the SPH and tropics: (1) NPH water ice opacity is greater at night than day at some seasons (2) The diurnal thermal tide controls the daily variability. (3) Strong day/night changes indicate that the amount of gas in the atmosphere varies significantly. See significant mixtures of dust and ice at the same altitude planet-wide (1) Points to a complex radiative and thermal balance between dust heating (in the visible) and ice heating or cooling in the infrared. Aerosol layering: (1) Early seasons reveal a zonally banded spatial distribution (2) Some localized longitudinal structure of aerosol layers (3) Later seasons show no consistent large scale organization

  1. Competition for water vapour results in suppression of ice formation in mixed-phase clouds

    Directory of Open Access Journals (Sweden)

    E. L. Simpson

    2018-05-01

    Full Text Available The formation of ice in clouds can initiate precipitation and influence a cloud's reflectivity and lifetime, affecting climate to a highly uncertain degree. Nucleation of ice at elevated temperatures requires an ice nucleating particle (INP, which results in so-called heterogeneous freezing. Previously reported measurements for the ability of a particle to nucleate ice have been made in the absence of other aerosol which will act as cloud condensation nuclei (CCN and are ubiquitous in the atmosphere. Here we show that CCN can outcompete INPs for available water vapour thus suppressing ice formation, which has the potential to significantly affect the Earth's radiation budget. The magnitude of this suppression is shown to be dependent on the mass of condensed water required for freezing. Here we show that ice formation in a state-of-the-art cloud parcel model is strongly dependent on the criteria for heterogeneous freezing selected from those previously hypothesised. We have developed an alternative criteria which agrees well with observations from cloud chamber experiments. This study demonstrates the dominant role that competition for water vapour can play in ice formation, highlighting both a need for clarity in the requirements for heterogeneous freezing and for measurements under atmospherically appropriate conditions.

  2. Competition for water vapour results in suppression of ice formation in mixed-phase clouds

    Science.gov (United States)

    Simpson, Emma L.; Connolly, Paul J.; McFiggans, Gordon

    2018-05-01

    The formation of ice in clouds can initiate precipitation and influence a cloud's reflectivity and lifetime, affecting climate to a highly uncertain degree. Nucleation of ice at elevated temperatures requires an ice nucleating particle (INP), which results in so-called heterogeneous freezing. Previously reported measurements for the ability of a particle to nucleate ice have been made in the absence of other aerosol which will act as cloud condensation nuclei (CCN) and are ubiquitous in the atmosphere. Here we show that CCN can outcompete INPs for available water vapour thus suppressing ice formation, which has the potential to significantly affect the Earth's radiation budget. The magnitude of this suppression is shown to be dependent on the mass of condensed water required for freezing. Here we show that ice formation in a state-of-the-art cloud parcel model is strongly dependent on the criteria for heterogeneous freezing selected from those previously hypothesised. We have developed an alternative criteria which agrees well with observations from cloud chamber experiments. This study demonstrates the dominant role that competition for water vapour can play in ice formation, highlighting both a need for clarity in the requirements for heterogeneous freezing and for measurements under atmospherically appropriate conditions.

  3. Sea-ice cover in the Nordic Seas and the sensitivity to Atlantic water temperatures

    Science.gov (United States)

    Jensen, Mari F.; Nisancioglu, Kerim H.; Spall, Michael A.

    2017-04-01

    Changes in the sea-ice cover of the Nordic Seas have been proposed to play a key role for the dramatic temperature excursions associated with the Dansgaard-Oeschger events during the last glacial. However, with its proximity to the warm Atlantic water, how a sea-ice cover can persist in the Nordic Seas is not well understood. In this study, we apply an eddy-resolving configuration of the Massachusetts Institute of Technology general circulation model with an idealized topography to study the presence of sea ice in a Nordic Seas-like domain. We assume an infinite amount of warm Atlantic water present in the south by restoring the southern area to constant temperatures. The sea-surface temperatures are restored toward cold, atmospheric temperatures, and as a result, sea ice is present in the interior of the domain. However, the sea-ice cover in the margins of the Nordic Seas, an area with a warm, cyclonic boundary current, is sensitive to the amount of heat entering the domain, i.e., the restoring temperature in the south. When the temperature of the warm, cyclonic boundary current is high, the margins are free of sea ice and heat is released to the atmosphere. We show that with a small reduction in the temperature of the incoming Atlantic water, the Nordic Seas-like domain is fully covered in sea ice. Warm water is still entering the Nordic Seas, however, this happens at depths below a cold, fresh surface layer produced by melted sea ice. Consequently, the heat release to the atmosphere is reduced along with the eddy heat fluxes. Results suggest a threshold value in the amount of heat entering the Nordic Seas before the sea-ice cover disappears in the margins. We study the sensitivity of this threshold to changes in atmospheric temperatures and vertical diffusivity.

  4. The Large Scale Distribution of Water Ice in the Polar Regions of the Moon

    Science.gov (United States)

    Jordan, A.; Wilson, J. K.; Schwadron, N.; Spence, H. E.

    2017-12-01

    For in situ resource utilization, one must know where water ice is on the Moon. Many datasets have revealed both surface deposits of water ice and subsurface deposits of hydrogen near the lunar poles, but it has proved difficult to resolve the differences among the locations of these deposits. Despite these datasets disagreeing on how deposits are distributed on small scales, we show that most of these datasets do agree on the large scale distribution of water ice. We present data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO), LRO's Lunar Exploration Neutron Detector (LEND), the Neutron Spectrometer on Lunar Prospector (LPNS), LRO's Lyman Alpha Mapping Project (LAMP), LRO's Lunar Orbiter Laser Altimeter (LOLA), and Chandrayaan-1's Moon Mineralogy Mapper (M3). All, including those that show clear evidence for water ice, reveal surprisingly similar trends with latitude, suggesting that both surface and subsurface datasets are measuring ice. All show that water ice increases towards the poles, and most demonstrate that its signature appears at about ±70° latitude and increases poleward. This is consistent with simulations of how surface and subsurface cold traps are distributed with latitude. This large scale agreement constrains the origin of the ice, suggesting that an ancient cometary impact (or impacts) created a large scale deposit that has been rendered locally heterogeneous by subsequent impacts. Furthermore, it also shows that water ice may be available down to ±70°—latitudes that are more accessible than the poles for landing.

  5. Satellite altimetry in sea ice regions - detecting open water for estimating sea surface heights

    Science.gov (United States)

    Müller, Felix L.; Dettmering, Denise; Bosch, Wolfgang

    2017-04-01

    The Greenland Sea and the Farm Strait are transporting sea ice from the central Arctic ocean southwards. They are covered by a dynamic changing sea ice layer with significant influences on the Earth climate system. Between the sea ice there exist various sized open water areas known as leads, straight lined open water areas, and polynyas exhibiting a circular shape. Identifying these leads by satellite altimetry enables the extraction of sea surface height information. Analyzing the radar echoes, also called waveforms, provides information on the surface backscatter characteristics. For example waveforms reflected by calm water have a very narrow and single-peaked shape. Waveforms reflected by sea ice show more variability due to diffuse scattering. Here we analyze altimeter waveforms from different conventional pulse-limited satellite altimeters to separate open water and sea ice waveforms. An unsupervised classification approach employing partitional clustering algorithms such as K-medoids and memory-based classification methods such as K-nearest neighbor is used. The classification is based on six parameters derived from the waveform's shape, for example the maximum power or the peak's width. The open-water detection is quantitatively compared to SAR images processed while accounting for sea ice motion. The classification results are used to derive information about the temporal evolution of sea ice extent and sea surface heights. They allow to provide evidence on climate change relevant influences as for example Arctic sea level rise due to enhanced melting rates of Greenland's glaciers and an increasing fresh water influx into the Arctic ocean. Additionally, the sea ice cover extent analyzed over a long-time period provides an important indicator for a globally changing climate system.

  6. Patterns of ice nuclei from natural water sources in the mountains of Tirol, Austria

    Science.gov (United States)

    Baloh, Philipp; Hanlon, Regina; Pietsch, Renee; Anderson, Christopher; Schmale, David G., III; Grothe, Hinrich

    2017-04-01

    Heterogeneous ice nucleation—the process by which particles can nucleate ice between 0 and -35°C—is important for generating artificial snow. Though abiotic and biotic ice nuclei are present in many different natural and managed ecosystems, little is known about their nature, sources, and ecological roles. We collected samples of water and snow from the mountains of Tyrol, Austria in June, July, and November, 2016. The collected water was mostly from sources with minimal anthropogenic pollution, since most of the water from the sampled streams came from glacial melt. The samples were filtered through a 0.22μm filter, and microorganisms were cultured on different types of media. Resulting colonies were tested for their ice nucleation ability using a droplet freezing assay and identified to the level of the species. The unfiltered water and the filtered water will be subjected to additional assays using cryo microscopy and vibrational microscopy (IR and Raman- spectroscopy). Preliminary analyses suggested that the percentage of ice-nucleating microbes varied with season; greater percentages of ice nucleating microbes were present during colder months. The glacial melt also varies strongly over the year with the fraction of mineral dust suspended in it which serves as an inorganic ice nucleation agent. Further investigation of these samples may help to show the combined ice nuleation abilities of biological and non biological particles present in the mountains of Tirol, Austria. Future work may shed light on how the nucleation properties of the natural water changes with the time of the year and what may be responsible for these changes.

  7. Ice versus liquid water saturation in simulations of the indian summer monsoon

    Science.gov (United States)

    Glazer, Russell H.; Misra, Vasubandhu

    2018-02-01

    At the same temperature, below 0 °C, the saturation vapor pressure (SVP) over ice is slightly less than the SVP over liquid water. Numerical models use the Clausius-Clapeyron relation to calculate the SVP and relative humidity, but there is not a consistent method for the treatment of saturation above the freezing level where ice and mixed-phase clouds may be present. In the context of current challenges presented by cloud microphysics in climate models, we argue that a better understanding of the impact that this treatment has on saturation-related processes like cloud formation and precipitation, is needed. This study explores the importance of the SVP calculation through model simulations of the Indian summer monsoon (ISM) using the regional spectral model (RSM) at 15 km grid spacing. A combination of seasonal and multiyear simulations is conducted with two saturation parameterizations. In one, the SVP over liquid water is prescribed through the entire atmospheric column (woIce), and in another the SVP over ice is used above the freezing level (wIce). When SVP over ice is prescribed, a thermodynamic drying of the middle and upper troposphere above the freezing level occurs due to increased condensation. In the wIce runs, the model responds to the slight decrease in the saturation condition by increasing, relative to the SVP over liquid water only run, grid-scale condensation of water. Increased grid-scale mean seasonal precipitation is noted across the ISM region in the simulation with SVP over ice prescribed. Modification of the middle and upper troposphere moisture results in a decrease in mean seasonal mid-level cloud amount and an increase in high cloud amount when SVP over ice is prescribed. Multiyear simulations strongly corroborate the qualitative results found in the seasonal simulations regarding the impact of ice versus liquid water SVP on the ISM's mean precipitation and moisture field. The mean seasonal rainfall difference over All India between wIce

  8. Polygeneration system based on PEMFC, CPVT and electrolyzer: Dynamic simulation and energetic and economic analysis

    International Nuclear Information System (INIS)

    Calise, Francesco; Figaj, Rafal Damian; Massarotti, Nicola; Mauro, Alessandro; Vanoli, Laura

    2017-01-01

    Highlights: • A novel polygeneration system is presented. • System includes CPVT collectors, PEM fuel cell, absorption chiller and electrolyzer. • The system provides heating/cooling, domestic hot water, electricity, hydrogen and oxygen. • The system simple payback period is 12.5 years, 5.8 years in case of incentive. • The optimal fuel cell nominal power results 100 kW. - Abstract: This paper presents a dynamic simulation model and an energetic and economic analysis of novel polygeneration system. The system integrates: cogenerative Proton Exchange Membrane Fuel Cell (PEMFC), Concentrated PhotoVoltaic-Thermal (CPVT) collectors, alkaline electrolyzer and single-stage LiBr/H_2O absorption chiller. The plant is designed to supply electrical energy, space heating or cooling and domestic hot water for a small university building. The system produces hydrogen and oxygen, the first one is stored and then it is supplied to the fuel cell, while the second one is sold. The electrolyzer system is powered only by the CPVT collectors, only a small amount of the solar electrical energy is available to the user. Such electric energy along with the one produced by the PEM fuel cell are used by the user and/or supplied to the grid. The system is designed and dynamically simulated using TRNSYS software package. This study is based on a model previously developed by the authors. In particular, the system was modified in order to implement the new components (CPVT, alkaline electrolyzer, hydrogen and oxygen system) in this work. Special attention is paid to the control strategy of the proposed system in order to achieve the optimal system configuration. Daily, weekly and yearly results carried out with the dynamic simulation are presented. Finally, a sensitivity analysis was performed in order to determine the system performance as a function of the main design parameters. The energetic and economic analysis shows that the system can ensure significant energy savings and it

  9. The Regional Water Cycle and Water Ice Clouds in the Tharsis - Valles Marineris System

    Science.gov (United States)

    Leung, C. W. S.; Rafkin, S. C.

    2017-12-01

    The regional atmospheric circulation on Mars is highly influenced by local topographic gradients. Terrain-following air parcels forced along the slopes of the major Tharsis volcanoes and the steep canyon walls of Valles Marineris significantly impact the local water vapor concentration and the associated conditions for cloud formation. Using a non-hydrostatic mesoscale atmospheric model with aerosol & cloud microphysics, we investigate the meteorological conditions for water ice cloud formation in the coupled Tharsis - Valles Marineris system near the aphelion season. The usage of a limited area regional model ensures that topographic slopes are well resolved compared to the typical resolutions of a global-coverage general circulation model. The effects of shadowing and slope angle geometries on the energy budget is also taken into account. Diurnal slope winds in complex terrains are typically characterized by the reversal of wind direction twice per sol: upslope during the day, and downslope at night. However, our simulation results of the regional circulation and diurnal water cycle indicate substantial asymmetries in the day-night circulation. The convergence of moist air masses enters Valles Marineris via easterly flows, whereas dry air sweep across the plateau of the canyon system from the south towards the north. We emphasize the non-uniform vertical distribution of water vapor in our model results. Water vapor mixing ratios in the lower planetary boundary layer may be factors greater than the mixing ratio aloft. Water ice clouds are important contributors to the climatic forcing on Mars, and their effects on the mesoscale circulations in the Tharsis - Valles Marineris region significantly contribute to the regional perturbations in the large-scale global atmospheric circulation.

  10. Identification of Accretion as Grain Growth Mechanism in Astrophysically Relevant Water&ice Dusty Plasma Experiment

    Science.gov (United States)

    Marshall, Ryan S.; Chai, Kil-Byoung; Bellan, Paul M.

    2017-03-01

    The grain growth process in the Caltech water-ice dusty plasma experiment has been studied using a high-speed camera and a long-distance microscope lens. It is observed that (I) the ice grain number density decreases fourfold as the average grain major axis increases from 20 to 80 μm, (II) the major axis length has a log-normal distribution rather than a power-law dependence, and (III) no collisions between ice grains are apparent. The grains have a large negative charge resulting in strong mutual repulsion and this, combined with the fractal character of the ice grains, prevents them from agglomerating. In order for the grain kinetic energy to be sufficiently small to prevent collisions between ice grains, the volumetric packing factor (I.e., ratio of the actual volume to the volume of a circumscribing ellipsoid) of the ice grains must be less than ˜0.1 depending on the exact relative velocity of the grains in question. Thus, it is concluded that direct accretion of water molecules is very likely to dominate the observed ice grain growth.

  11. Protozoan Bacterivory in the Ice and the Water Column of a Cold Temperate Lagoon.

    Science.gov (United States)

    Sime-Ngando; Demers; Juniper

    1999-02-01

    > Abstract Bacterial abundance and bacterivorous protist abundance and activity were examined in ice-brine and water column communities of a cold temperate Japanese lagoon (Saroma-Ko Lagoon, Hokkaido, 44 degreesN, 144 degreesE), during the late winter phase of ice community development (February-March 1992). Bacterial abundance averaged 6 and 1 x 10(5) cells ml-1 in the ice-brine and plankton samples, respectively, and generally decreased during the sampling period. Bacterivorous protists, identified based on direct observation of short-term (Protist abundance averaged 4 x 10(3) and 8.1 cells ml-1 in the ice-brine and 0.3 x 10(3) and 1.2 cells ml-1 in the plankton, for flagellates and ciliates, respectively. In contrast to bacteria, the abundance of protists generally increased throughout the sampling period, indicating predator-prey interactions. Protistan bacterivory, measured from the rate of FLB disappearance over 24 h, averaged 36% (ice) and 24% (plankton) of bacterial standing stock and exhibited the same seasonal pattern as for protist abundance. The calculated specific clearance (range, 2-67 nl protozoa-1 h-1) and ingestion (protists" on nonbacterial food items were also provided. Although alternative sources of bacterial loss are likely to be of importance, this study provides evidence for the potential of protozoan assemblages as bacterial grazers in both sea ice-brine biota and water column at the southern limit of sea ice in the northern hemisphere.

  12. Thermal desorption of formamide and methylamine from graphite and amorphous water ice surfaces

    Science.gov (United States)

    Chaabouni, H.; Diana, S.; Nguyen, T.; Dulieu, F.

    2018-04-01

    Context. Formamide (NH2CHO) and methylamine (CH3NH2) are known to be the most abundant amine-containing molecules in many astrophysical environments. The presence of these molecules in the gas phase may result from thermal desorption of interstellar ices. Aims: The aim of this work is to determine the values of the desorption energies of formamide and methylamine from analogues of interstellar dust grain surfaces and to understand their interaction with water ice. Methods: Temperature programmed desorption (TPD) experiments of formamide and methylamine ices were performed in the sub-monolayer and monolayer regimes on graphite (HOPG) and non-porous amorphous solid water (np-ASW) ice surfaces at temperatures 40-240 K. The desorption energy distributions of these two molecules were calculated from TPD measurements using a set of independent Polanyi-Wigner equations. Results: The maximum of the desorption of formamide from both graphite and ASW ice surfaces occurs at 176 K after the desorption of H2O molecules, whereas the desorption profile of methylamine depends strongly on the substrate. Solid methylamine starts to desorb below 100 K from the graphite surface. Its desorption from the water ice surface occurs after 120 K and stops during the water ice sublimation around 150 K. It continues to desorb from the graphite surface at temperatures higher than160 K. Conclusions: More than 95% of solid NH2CHO diffuses through the np-ASW ice surface towards the graphitic substrate and is released into the gas phase with a desorption energy distribution Edes = 7460-9380 K, which is measured with the best-fit pre-exponential factor A = 1018 s-1. However, the desorption energy distribution of methylamine from the np-ASW ice surface (Edes = 3850-8420 K) is measured with the best-fit pre-exponential factor A = 1012 s-1. A fraction of solid methylamine monolayer of roughly 0.15 diffuses through the water ice surface towards the HOPG substrate. This small amount of methylamine

  13. Drag Moderation by the Melting of an Ice Surface in Contact with Water

    KAUST Repository

    Vakarelski, Ivan Uriev

    2015-07-24

    We report measurements of the effects of a melting ice surface on the hydrodynamic drag of ice-shell-metal-core spheres free falling in water at a Reynolds of number Re∼2×104–3×105 and demonstrate that the melting surface induces the early onset of the drag crisis, thus reducing the hydrodynamic drag by more than 50%. Direct visualization of the flow pattern demonstrates the key role of surface melting. Our observations support the hypothesis that the drag reduction is due to the disturbance of the viscous boundary layer by the mass transfer from the melting ice surface.

  14. Drag Moderation by the Melting of an Ice Surface in Contact with Water

    KAUST Repository

    Vakarelski, Ivan Uriev; Chan, Derek Y.  C.; Thoroddsen, Sigurdur T

    2015-01-01

    We report measurements of the effects of a melting ice surface on the hydrodynamic drag of ice-shell-metal-core spheres free falling in water at a Reynolds of number Re∼2×104–3×105 and demonstrate that the melting surface induces the early onset of the drag crisis, thus reducing the hydrodynamic drag by more than 50%. Direct visualization of the flow pattern demonstrates the key role of surface melting. Our observations support the hypothesis that the drag reduction is due to the disturbance of the viscous boundary layer by the mass transfer from the melting ice surface.

  15. Cavitation and water fluxes driven by ice water potential in Juglans regia during freeze-thaw cycles.

    Science.gov (United States)

    Charra-Vaskou, Katline; Badel, Eric; Charrier, Guillaume; Ponomarenko, Alexandre; Bonhomme, Marc; Foucat, Loïc; Mayr, Stefan; Améglio, Thierry

    2016-02-01

    Freeze-thaw cycles induce major hydraulic changes due to liquid-to-ice transition within tree stems. The very low water potential at the ice-liquid interface is crucial as it may cause lysis of living cells as well as water fluxes and embolism in sap conduits, which impacts whole tree-water relations. We investigated water fluxes induced by ice formation during freeze-thaw cycles in Juglans regia L. stems using four non-invasive and complementary approaches: a microdendrometer, magnetic resonance imaging, X-ray microtomography, and ultrasonic acoustic emissions analysis. When the temperature dropped, ice nucleation occurred, probably in the cambium or pith areas, inducing high water potential gradients within the stem. The water was therefore redistributed within the stem toward the ice front. We could thus observe dehydration of the bark's living cells leading to drastic shrinkage of this tissue, as well as high tension within wood conduits reaching the cavitation threshold in sap vessels. Ultrasonic emissions, which were strictly emitted only during freezing, indicated cavitation events (i.e. bubble formation) following ice formation in the xylem sap. However, embolism formation (i.e. bubble expansion) in stems was observed only on thawing via X-ray microtomography for the first time on the same sample. Ultrasonic emissions were detected during freezing and were not directly related to embolism formation. These results provide new insights into the complex process and dynamics of water movements and ice formation during freeze-thaw cycles in tree stems. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  16. Seasonally-Active Water on Mars: Vapour, Ice, Adsorbate, and the Possibility of Liquid

    Science.gov (United States)

    Richardson, M. I.

    2002-12-01

    Seasonally-active water can be defined to include any water reservoir that communicates with other reservoirs on time scales of a year or shorter. It is the interaction of these water reservoirs, under the influence of varying solar radiation and in conjunction with surface and atmospheric temperatures, that determines the phase-stability field for water at the surface, and the distribution of water in various forms below, on, and above the surface. The atmosphere is the critical, dynamical link in this cycling system, and also (fortunately) one of the easiest to observe. Viking and Mars Global Surveyor observations paint a strongly asymmetric picture of the global seasonal water cycle, tied proximately to planetary eccentricity, and the existence of residual ice caps of different composition at the two poles. The northern summer experiences the largest water vapour columns, and is associated with sublimation from the northern residual water ice cap. The southern summer residual carbon dioxide ice cap is cold trap for water. Asymmetry in the water cycle is an unsolved problem. Possible solutions may involve the current timing of perihelion (the water cap resides at the pole experiencing the longer but cooler summer), the trapping of water ice in the northern hemisphere by tropical water ice clouds, and the bias in the annual-average, zonal-mean atmospheric circulation resulting from the zonal-mean difference in the elevation of the northern and southern hemispheres. Adsorbed and frozen water have proven harder to constrain. Recent Odyssey Gamma Ray Spectrometer results suggest substantial ground ice in the mid- and high-latitudes, but this water is likely below the seasonal skin depth for two reasons: the GRS results are best fit with such a model, and GCM models of the water cycle produce dramatically unrealistic atmospheric vapour distributions when such a very near surface, GRS-like distribution is initialized - ultimately removing the water to the northern and

  17. Electron Density Dropout Near Enceladus in the Context of Water-Vapor and Water-Ice

    Science.gov (United States)

    Farrell, W. M.; Kurth, W. S.; Gurnett, D. A.; Johnson, R. E.; Kaiser, M. L.; Wahlund, J.-E.; Waite, J. H., Jr.

    2009-01-01

    On 12 March 2008, the Cassini spacecraft made a close encounter with the Saturnian moon Enceladus, passing within 52 km of the moon. The spacecraft trajectory was intentionally-oriented in a southerly direction to create a close alignment with the intense water-dominated plumes emitted from the south polar region. During the passage, the Cassini Radio and Plasma Wave System (RPWS) detected two distinct radio signatures: 1) Impulses associated with small water-ice dust grain impacts and 2) an upper hybrid (UH) resonance emission that both intensified and displayed a sharp frequency decrease in the near-vicinity of the moon. The frequency decrease of the UH emission is associated with an unexpectedly sharp decrease in electron density from approximately 90 el/cubic cm to below 20 el/cubic cm that occurs on a time scale of a minute near the closest encounter with the moon. In this work, we consider a number of scenarios to explain this sharp electron dropout, but surmise that electron absorption by ice grains is the most likely process.

  18. Radar and infrared remote sensing of terrain, water resources, arctic sea ice, and agriculture

    Science.gov (United States)

    Biggs, A. W.

    1983-01-01

    Radar range measurements, basic waveforms of radar systems, and radar displays are initially described. These are followed by backscatter from several types of terrain and vegetation as a function of frequency and grazing angle. Analytical models for this backscatter include the facet models of radar return, with range-angle, velocity-range, velocity-angle, range, velocity, and angular only discriminations. Several side-looking airborne radar geometries are presented. Radar images of Arctic sea ice, fresh water lake ice, cloud-covered terrain, and related areas are presented to identify applications of radar imagery. Volume scatter models are applied to radar imagery from alpine snowfields. Short pulse ice thickness radar for subsurface probes is discussed in fresh-water ice and sea ice detection. Infrared scanners, including multispectral, are described. Diffusion of cold water into a river, Arctic sea ice, power plant discharges, volcanic heat, and related areas are presented in thermal imagery. Multispectral radar and infrared imagery are discussed, with comparisons of photographic, infrared, and radar imagery of the same terrain or subjects.

  19. Vertical Distribution of Dust and Water Ice Aerosols from CRISM Limb-geometry Observations

    Science.gov (United States)

    Smith, Michael Doyle; Wolff, Michael J.; Clancy, Todd; Kleinbohl, Armin; Murchie, Scott L.

    2013-01-01

    [1] Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board the Mars Reconnaissance Orbiter provide a useful tool for probing atmospheric structure. Specifically, the observed radiance as a function of wavelength and height above the limb enables the vertical distribution of both dust and water ice aerosols to be retrieved. More than a dozen sets of CRISM limb observations have been taken so far providing pole-to-pole cross sections, spanning more than a full Martian year. Radiative transfer modeling is used to model the observations taking into account multiple scattering from aerosols and the spherical geometry of the limb observations. Both dust and water ice vertical profiles often show a significant vertical structure for nearly all seasons and latitudes that is not consistent with the well-mixed or Conrath-v assumptions that have often been used in the past for describing aerosol vertical profiles for retrieval and modeling purposes. Significant variations are seen in the retrieved vertical profiles of dust and water ice aerosol as a function of season. Dust typically extends to higher altitudes (approx. 40-50km) during the perihelion season than during the aphelion season (water ice clouds are common, and water ice aerosols are observed to cap the dust layer in all seasons.

  20. Air-sea flux of CO2 in arctic coastal waters influenced by glacial melt water and sea ice

    DEFF Research Database (Denmark)

    Sejr, Mikael Kristian; Krause-Jensen, Dorte; Rysgaard, Søren

    2011-01-01

    Annual air–sea exchange ofCO2 inYoung Sound,NEGreenlandwas estimated using pCO2 surface-water measurements during summer (2006–2009) and during an ice-covered winter 2008. All surface pCO2 values were below atmospheric levels indicating an uptake of atmospheric CO2. During sea ice formation...... and thereby efficiently blocked air–sea CO2 exchange. During sea ice melt, dissolution of CaCO3 combined with primary production and strong stratification of the water column acted to lower surface-water pCO2 levels in the fjord. Also, a large input of glacial melt water containing geochemically reactive...... year-to-year variation in annual gas exchange....

  1. Electrophysiological and behavioural responses of turbot (Scophthalmus maximus) cooled in ices water

    NARCIS (Netherlands)

    Lambooij, E.; Bracke, M.B.M.; Reimert, H.G.M.; Foss, A.; Imsland, A.; Vis, van de J.W.

    2015-01-01

    Behavioural, neural and physiological aspects related to pre-slaughter cooling of turbot habituated to two environmental temperatures (18.7 and 12.0 °C) were investigated. Six fish in both treatments were immersed in ice water for 75 min. For control, four fish were immersed in water under their

  2. A Molecular Explanation of How the Fog Is Produced When Dry Ice Is Placed in Water

    Science.gov (United States)

    Kuntzleman, Thomas S.; Ford, Nathan; No, Jin-Hwan; Ott, Mark E.

    2015-01-01

    Everyone enjoys seeing the cloudy white fog generated when solid carbon dioxide (dry ice) is placed in water. Have you ever wondered what physical and chemical processes occur to produce this fog? When asked this question, many chemical educators suggest that the fog is produced when atmospheric water vapor condenses on cold carbon dioxide gas…

  3. Water droplet behavior on superhydrophobic SiO2 nanocomposite films during icing/deicing cycles

    NARCIS (Netherlands)

    Lazauskas, A.; Guobiene, A.; Prosycevas, I.; Baltrusaitis, V.; Grigaliunas, V.; Narmontas, P.; Baltrusaitis, Jonas

    2013-01-01

    This work investigates water droplet behavior on superhydrophobic (water contact angle value of 162 ± 1°) SiO2 nanocomposite films subjected to repetitive icing/deicing treatments, changes in SiO2 nanocomposite film surface morphology and their non-wetting characteristics. During the experiment,

  4. Investigation of heterogeneous ice nucleation in pollen suspensions and washing water

    Science.gov (United States)

    Dreischmeier, Katharina; Budke, Carsten; Koop, Thomas

    2014-05-01

    Biological particles such as pollen often show ice nucleation activity at temperatures higher than -20 °C. Immersion freezing experiments of pollen washing water demonstrate comparable ice nucleation behaviour as water containing the whole pollen bodies (Pummer et al., 2012). It was suggested that polysaccharide molecules leached from the grains are responsible for the ice nucleation. Here, heterogeneous ice nucleation in birch pollen suspensions and their washing water was investigated by two different experimental methods. The optical freezing array BINARY (Bielefeld Ice Nucleation ARraY) allows the direct observation of freezing of microliter-sized droplets. The IN spectra obtained from such experiments with birch pollen suspensions over a large concentration range indicate several different ice nucleation active species, two of which are present also in the washing water. The latter was probed also in differential scanning calorimeter (DSC) experiments of emulsified sub-picoliter droplets. Due to the small droplet size in the emulsion samples and at small concentration of IN in the washing water, such DSC experiments can exhibit the ice nucleation behaviour of a single nucleus. The two heterogeneous freezing signals observed in the DSC thermograms can be assigned to two different kinds of ice nuclei, confirming the observation from the BINARY measurements, and also previous studies on Swedish birch pollen washing water (Augustin et al., 2012). The authors gratefully acknowledge funding by the German Research Foundation (DFG) through the project BIOCLOUDS (KO 2944/1-1) and through the research unit INUIT (FOR 1525) under KO 2944/2-1. We particularly thank our INUIT partners for fruitful collaboration and sharing of ideas and IN samples. S. Augustin, H. Wex, D. Niedermeier, B. Pummer, H. Grothe, S. Hartmann, L. Tomsche, T. Clauss, J. Voigtländer, K. Ignatius, and F. Stratmann, Immersion freezing of birch pollen washing water, Atmos. Chem. Phys., 13, 10989

  5. Modelling of destructive ability of water-ice-jet while machine processing of machine elements

    Directory of Open Access Journals (Sweden)

    Burnashov Mikhail

    2017-01-01

    Full Text Available This paper represents the classification of the most common contaminants, appearing on the surfaces of machine elements after a long-term service.The existing well-known surface cleaning methods are described and analyzed in the framework of this paper. The article is intended to provide the reader with an understanding of the process of cleaning and removing contamination from machine elements surface by means of water-ice-jet with preprepared beforehand particles, as well as the process of water-ice-jet formation. The paper deals with the description of such advantages of this method as low costs, wastelessness, high quality of the surface, undergoing processing, minimization of harmful impact upon environment and eco-friendliness, which makes it differ radically from formerly known methods. The scheme of interection between the surface and ice particle is represented. A thermo-physical model of destruction of contaminants by means of a water-ice-jet cleaning technology was developed on its basis. The thermo-physical model allows us to make setting of processing mode and the parameters of water-ice-jet scientifically substantiated and well-grounded.

  6. EPR Evidence of Liquid Water in Ice: An Intrinsic Property of Water or a Self-Confinement Effect?

    Science.gov (United States)

    Thangswamy, Muthulakshmi; Maheshwari, Priya; Dutta, Dhanadeep; Rane, Vinayak; Pujari, Pradeep K

    2018-06-01

    Liquid water (LW) existence in pure ice below 273 K has been a controversial aspect primarily because of the lack of experimental evidence. Recently, electron paramagnetic resonance (EPR) has been used to study deeply supercooled water in a rapidly frozen polycrystalline ice. The same technique can also be used to probe the presence of LW in polycrystalline ice that has formed through a more conventional, slow cooling one. In this context, the present study aims to emphasize that in case of an external probe involving techniques such as EPR, the results are influenced by the binary phase (BP) diagram of the probe-water system, which also predicts the existence of LW domains in ice, up to the eutectic point. Here we report the results of our such EPR spin-probe studies on water, which demonstrate that smaller the concentration of the probe stronger is the EPR evidence of liquid domains in polycrystalline ice. We used computer simulations based on stochastic Liouville theory to analyze the lineshapes of the EPR spectra. We show that the presence of the spin probe modifies the BP diagram of water, at very low concentrations of the spin probe. The spin probe thus acts, not like a passive reporter of the behavior of the solvent and its environment, but as an active impurity to influence the solvent. We show that there exists a lower critical concentration, below which BP diagram needs to be modified, by incorporating the effect of confinement of the spin probe. With this approach, we demonstrate that the observed EPR evidence of LW domains in ice can be accounted for by the modified BP diagram of the probe-water system. The present work highlights the importance of taking cognizance of the possibility of spin probes affecting the host systems, when interpreting the EPR (or any other probe based spectroscopic) results of phase transitions of host, as its ignorance may lead to serious misinterpretations.

  7. Design of the electrolyzer for the solar hydrogen production system

    International Nuclear Information System (INIS)

    Ibrahim, M.; Kamaruzzaman Sopian; Wan Ramli Wan Daud

    2006-01-01

    This paper presents the theoretical design of hydrogen system. Also, it shown the details steps of theoretical calculation to produce the required amount of hydrogen. Hydrogen is considered the fuel of the future. It is promising alternative for fossil fuel. Since, it is non-pollutant and renewable. The system contains and required equipment are photovoltaic panel, energy storage battery, converter, electrolyzer and hydrogen storage. By using 1.7 V supplied by PV, the simulation results gives 89 1/day of hydrogen. Since, the electrolyzer efficiency assumed to be 50%

  8. An Efficiency Model For Hydrogen Production In A Pressurized Electrolyzer

    Energy Technology Data Exchange (ETDEWEB)

    Smoglie, Cecilia; Lauretta, Ricardo

    2010-09-15

    The use of Hydrogen as clean fuel at a world wide scale requires the development of simple, safe and efficient production and storage technologies. In this work, a methodology is proposed to produce Hydrogen and Oxygen in a self pressurized electrolyzer connected to separate containers that store each of these gases. A mathematical model for Hydrogen production efficiency is proposed to evaluate how such efficiency is affected by parasitic currents in the electrolytic solution. Experimental set-up and results for an electrolyzer are also presented. Comparison of empirical and analytical results shows good agreement.

  9. Cloud screening and melt water detection over melting sea ice using AATSR/SLSTR

    Science.gov (United States)

    Istomina, Larysa; Heygster, Georg

    2014-05-01

    With the onset of melt in the Arctic Ocean, the fraction of melt water on sea ice, the melt pond fraction, increases. The consequences are: the reduced albedo of sea ice, increased transmittance of sea ice and affected heat balance of the system with more heat passing through the ice into the ocean, which facilitates further melting. The onset of melt, duration of melt season and melt pond fraction are good indicators of the climate state of the Arctic and its change. In the absence of reliable sea ice thickness retrievals in summer, melt pond fraction retrieval from satellite is in demand as input for GCM as an indicator of melt state of the sea ice. The retrieval of melt pond fraction with a moderate resolution radiometer as AATSR is, however, a non-trivial task due to a variety of subpixel surface types with very different optical properties, which give non-unique combinations if mixed. In this work this has been solved by employing additional information on the surface and air temperature of the pixel. In the current work, a concept of melt pond detection on sea ice is presented. The basis of the retrieval is the sensitivity of AATSR reflectance channels 550nm and 860nm to the amount of melt water on sea ice. The retrieval features extensive usage of a database of in situ surface albedo spectra. A tree of decisions is employed to select the feasible family of in situ spectra for the retrieval, depending on the melt stage of the surface. Reanalysis air temperature at the surface and brightness temperature measured by the satellite sensor are analyzed in order to evaluate the melting status of the surface. Case studies for FYI and MYI show plausible retrieved melt pond fractions, characteristic for both of the ice types. The developed retrieval can be used to process the historical AATSR (2002-2012) dataset, as well as for the SLSTR sensor onboard the future Sentinel-3 mission (scheduled for launch in 2015), to keep the continuity and obtain longer time sequence

  10. Nonthermal ice nucleation observed at distorted contact lines of supercooled water drops.

    Science.gov (United States)

    Yang, Fan; Cruikshank, Owen; He, Weilue; Kostinski, Alex; Shaw, Raymond A

    2018-02-01

    Ice nucleation is the crucial step for ice formation in atmospheric clouds and therefore underlies climatologically relevant precipitation and radiative properties. Progress has been made in understanding the roles of temperature, supersaturation, and material properties, but an explanation for the efficient ice nucleation occurring when a particle contacts a supercooled water drop has been elusive for over half a century. Here, we explore ice nucleation initiated at constant temperature and observe that mechanical agitation induces freezing of supercooled water drops at distorted contact lines. Results show that symmetric motion of supercooled water on a vertically oscillating substrate does not freeze, no matter how we agitate it. However, when the moving contact line is distorted with the help of trace amounts of oil or inhomogeneous pinning on the substrate, freezing can occur at temperatures much higher than in a static droplet, equivalent to ∼10^{10} increase in nucleation rate. Several possible mechanisms are proposed to explain the observations. One plausible explanation among them, decreased pressure due to interface curvature, is explored theoretically and compared with the observational results quasiquantitatively. Indeed, the observed freezing-temperature increase scales with contact line speed in a manner consistent with the pressure hypothesis. Whatever the mechanism, the experiments demonstrate a strong preference for ice nucleation at three-phase contact lines compared to the two-phase interface, and they also show that movement and distortion of the contact line are necessary contributions to stimulating the nucleation process.

  11. Multipole moments of water molecules in clusters and ice Ih from first principles calculations

    International Nuclear Information System (INIS)

    Batista, E.R.; Xantheas, S.S.; Jonsson, H.

    1999-01-01

    We have calculated molecular multipole moments for water molecules in clusters and in ice Ih by partitioning the charge density obtained from first principles calculations. Various schemes for dividing the electronic charge density among the water molecules were used. They include Bader close-quote s zero flux surfaces and Voronoi partitioning schemes. A comparison was also made with an induction model including dipole, dipole-quadrupole, quadrupole-quadrupole polarizability and first hyperpolarizability as well as fixed octopole and hexadecapole moments. We have found that the different density partitioning schemes lead to widely different values for the molecular multipoles, illustrating how poorly defined molecular multipoles are in clusters and condensed environments. For instance, the magnitude of the molecular dipole moment in ice Ih ranges between 2.3 D and 3.1 D depending on the partitioning scheme used. Within each scheme, though, the value for the molecular dipole moment in ice is larger than in the hexamer. The magnitude of the molecular dipole moment in the clusters shows a monotonic increase from the gas phase value to the one in ice Ih, with the molecular dipole moment in the water ring hexamer being smaller than the one in ice Ih for all the partitioning schemes used. copyright 1999 American Institute of Physics

  12. Hydroelectric power development and the ice regime of inland waters: A northern community perspective

    International Nuclear Information System (INIS)

    Gerard, R.

    1989-03-01

    Inland waters play a vital role in the life of the many small northern communities which depend in large measure on the provisions of the natural environment for their sustenance. These communities are therefore particularly vulnerable to changes in the ice regime of these waters, especially changes that are irregular. However, the north is also the site of much of Canada's hydroelectric power development and potential, developments that have a major influence on the ice regime of effected waters. As a contribution to the background information required for the necessary discussions and negotiations associated with such developments, the various aspects of the natural ice regime, the possible effects of hydroelectric development and operation on this regime, and its consequences, are briefly reviewed. The emphasis has been placed on changes that will likely be of most significance to northern communities in the bedrock-controlled country of the western Canadian Shield. The major direct, and in some circumstances life-threatening, impact of changes to the ice regime is on trafficability of the iceways that play such a vital role in the life of the communities. Hence particular emphasis has been placed on this aspect and on the formation of the slush and thin ice conditions that are the bane of over-ice travel and that are subject to unexpected changes by hydroelectric development and operation. To place these changes and their effects in some perspective, the nature of a hydroelectric development is also briefly described and an effort made to indicate the large costs incurred if these developments are restrained in their operation to avoid or mitigate some of the effects on the ice regime. 31 refs., 57 figs., 1 tab

  13. High Ice Water Concentrations in the 19 August 2015 Coastal Mesoconvective System

    Science.gov (United States)

    Proctor, Fred H.; Harrah, Steven; Switzer, George F.; Strickland, Justin K.; Hunt, Patricia J.

    2017-01-01

    During August 2015, NASA's DC-8 research aircraft was flown into High Ice Water Content (HIWC) events as part of a three-week campaign to collect airborne radar data and to obtain measurements from microphysical probes. Goals for this flight campaign included improved characterization of HIWC events, especially from an airborne radar perspective. This paper focuses on one of the flight days, in which a coastal mesoscale convective system (MCS) was investigated for HIWC conditions. The system appears to have been maintained by bands of convection flowing in from the Gulf of Mexico. These convective bands were capped by a large cloud canopy, which masks the underlying structure if viewed from an infrared sensing satellite. The DC-8 was equipped with an IsoKinetic Probe that measured ice concentrations of up to 2.3 g m(exp -3) within the cloud canopy of this system. Sustained measurements of ice crystals with concentrations exceeding 1 g m(exp -3) were encountered for up to ten minutes of flight time. Airborne Radar reflectivity factors were found to be weak within these regions of high ice water concentrations, suggesting that Radar detection of HIWC would be a challenging endeavor. This case is then investigated using a three-dimensional numerical cloud model. Profiles of ice water concentrations and radar reflectivity factor demonstrate similar magnitudes and scales between the flight measurements and model simulation. Also discussed are recent modifications to the numerical model's ice-microphysics that are based on measurements during the flight campaign. The numerical model and its updated ice-microphysics are further validated with a simulation of a well-known case of a supercell hailstorm measured during the Cooperative Convective Precipitation Experiment. Differences in HIWC between the continental supercell and the coastal MCS are discussed.

  14. Ice and water droplets on graphite: A comparison of quantum and classical simulations

    International Nuclear Information System (INIS)

    Ramírez, Rafael; Singh, Jayant K.; Müller-Plathe, Florian; Böhm, Michael C.

    2014-01-01

    Ice and water droplets on graphite have been studied by quantum path integral and classical molecular dynamics simulations. The point-charge q-TIP4P/F potential was used to model the interaction between flexible water molecules, while the water-graphite interaction was described by a Lennard-Jones potential previously used to reproduce the macroscopic contact angle of water droplets on graphite. Several energetic and structural properties of water droplets with sizes between 10 2 and 10 3 molecules were analyzed in a temperature interval of 50–350 K. The vibrational density of states of crystalline and amorphous ice drops was correlated to the one of ice Ih to assess the influence of the droplet interface and molecular disorder on the vibrational properties. The average distance of covalent OH bonds is found 0.01 Å larger in the quantum limit than in the classical one. The OO distances are elongated by 0.03 Å in the quantum simulations at 50 K. Bond distance fluctuations are large as a consequence of the zero-point vibrations. The analysis of the H-bond network shows that the liquid droplet is more structured in the classical limit than in the quantum case. The average kinetic and potential energy of the ice and water droplets on graphite has been compared with the values of ice Ih and liquid water as a function of temperature. The droplet kinetic energy shows a temperature dependence similar to the one of liquid water, without apparent discontinuity at temperatures where the droplet is solid. However, the droplet potential energy becomes significantly larger than the one of ice or water at the same temperature. In the quantum limit, the ice droplet is more expanded than in a classical description. Liquid droplets display identical density profiles and liquid-vapor interfaces in the quantum and classical limits. The value of the contact angle is not influenced by quantum effects. Contact angles of droplets decrease as the size of the water droplet increases

  15. Benchmarking a first-principles thermal neutron scattering law for water ice with a diffusion experiment

    Directory of Open Access Journals (Sweden)

    Holmes Jesse

    2017-01-01

    Full Text Available The neutron scattering properties of water ice are of interest to the nuclear criticality safety community for the transport and storage of nuclear materials in cold environments. The common hexagonal phase ice Ih has locally ordered, but globally disordered, H2O molecular orientations. A 96-molecule supercell is modeled using the VASP ab initio density functional theory code and PHONON lattice dynamics code to calculate the phonon vibrational spectra of H and O in ice Ih. These spectra are supplied to the LEAPR module of the NJOY2012 nuclear data processing code to generate thermal neutron scattering laws for H and O in ice Ih in the incoherent approximation. The predicted vibrational spectra are optimized to be representative of the globally averaged ice Ih structure by comparing theoretically calculated and experimentally measured total cross sections and inelastic neutron scattering spectra. The resulting scattering kernel is then supplied to the MC21 Monte Carlo transport code to calculate time eigenvalues for the fundamental mode decay in ice cylinders at various temperatures. Results are compared to experimental flux decay measurements for a pulsed-neutron die-away diffusion benchmark.

  16. Viscous organic aerosol particles in the upper troposphere: diffusivity-controlled water uptake and ice nucleation?

    Directory of Open Access Journals (Sweden)

    D. M. Lienhard

    2015-12-01

    secondary organic aerosol (SOA material produced by oxidation of α-pinene and in a number of organic/inorganic model mixtures (3-methylbutane-1,2,3-tricarboxylic acid (3-MBTCA, levoglucosan, levoglucosan/NH4HSO4, raffinose are presented. These indicate that water diffusion coefficients are determined by several properties of the aerosol substance and cannot be inferred from the glass transition temperature or bouncing properties. Our results suggest that water diffusion in SOA particles is faster than often assumed and imposes no significant kinetic limitation on water uptake and release at temperatures above 220 K. The fast diffusion of water suggests that heterogeneous ice nucleation on a glassy core is very unlikely in these systems. At temperatures below 220 K, model simulations of SOA particles suggest that heterogeneous ice nucleation may occur in the immersion mode on glassy cores which remain embedded in a liquid shell when experiencing fast updraft velocities. The particles absorb significant quantities of water during these updrafts which plasticize their outer layers such that these layers equilibrate readily with the gas phase humidity before the homogeneous ice nucleation threshold is reached. Glass formation is thus unlikely to restrict homogeneous ice nucleation. Only under most extreme conditions near the very high tropical tropopause may the homogeneous ice nucleation rate coefficient be reduced as a consequence of slow condensed-phase water diffusion. Since the differences between the behavior limited or non limited by diffusion are small even at the very high tropical tropopause, condensed-phase water diffusivity is unlikely to have significant consequences on the direct climatic effects of SOA particles under tropospheric conditions.

  17. PHOTOCHEMISTRY OF POLYCYCLIC AROMATIC HYDROCARBONS IN COSMIC WATER ICE: THE ROLE OF PAH IONIZATION AND CONCENTRATION

    International Nuclear Information System (INIS)

    Cook, Amanda M.; Mattioda, Andrew L.; Roser, Joseph; Bregman, Jonathan; Ricca, Alessandra; Allamandola, Louis J.; Bouwman, Jordy; Linnartz, Harold

    2015-01-01

    Infrared spectroscopic studies of ultraviolet (UV) irradiated, water-rich, cosmic ice analogs containing small polycyclic aromatic hydrocarbons (PAHs) are described. The irradiation studies of anthracene:H 2 O, pyrene:H 2 O, and benzo[ghi]perylene:H 2 O ices (14 K) at various concentrations reported by Bouwman et al. are extended. While aromatic alcohols and ketones have been reported in residues after irradiated PAH:H 2 O ices were warmed to 270 K, it was not known if they formed during ice irradiation or during warm-up when reactants interact as H 2 O sublimes. Recent work has shown that they form in low temperature ice. Using DFT computed IR spectra to identify photoproducts and PAH cations, we tentatively identify the production of specific alcohols [PAH(OH) n ] and quinones [PAH(O) n ] for all PAH:H 2 O ices considered here. Little evidence is found for hydrogenation at 14 K, consistent with the findings of Gudipati and Yang. Addition of O and OH to the parent PAH is the dominant photochemical reaction, but PAH erosion to smaller PAHs (producing CO 2 and H 2 CO) is also important. DFT spectra are used to assess the contribution of PAH-related species to interstellar absorption features from 5 to 9 μm. The case is made that PAH cations are important contributors to the C2 component and PAH(OH) n and PAH(O) n to the C5 component described by Boogert et al. Thus, interstellar ices should contain neutral and ionized PAHs, alcohols, ketones and quinones at the ∼2%-4% level relative to H 2 O. PAHs, their photoproducts, and ion-mediated processes should therefore be considered when modeling interstellar ice processes

  18. PHOTOCHEMISTRY OF POLYCYCLIC AROMATIC HYDROCARBONS IN COSMIC WATER ICE: THE ROLE OF PAH IONIZATION AND CONCENTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Amanda M.; Mattioda, Andrew L.; Roser, Joseph; Bregman, Jonathan [NASA Ames Research Center, PO Box 1, M/S 245-6, Moffett Field, CA 94035 (United States); Ricca, Alessandra; Allamandola, Louis J. [SETI Institute, 189 North Bernardo Avenue, Mountain View, CA 94043 (United States); Bouwman, Jordy [Radboud University Nijmegen, Institute for Molecules and Materials, Toernooiveld 5, 6525 ED Nijmegen (Netherlands); Linnartz, Harold [Sackler Laboratory for Astrophysics, Leiden Observatory, University of Leiden, PO Box 9513, NL2300 RA Leiden (Netherlands)

    2015-01-20

    Infrared spectroscopic studies of ultraviolet (UV) irradiated, water-rich, cosmic ice analogs containing small polycyclic aromatic hydrocarbons (PAHs) are described. The irradiation studies of anthracene:H{sub 2}O, pyrene:H{sub 2}O, and benzo[ghi]perylene:H{sub 2}O ices (14 K) at various concentrations reported by Bouwman et al. are extended. While aromatic alcohols and ketones have been reported in residues after irradiated PAH:H{sub 2}O ices were warmed to 270 K, it was not known if they formed during ice irradiation or during warm-up when reactants interact as H{sub 2}O sublimes. Recent work has shown that they form in low temperature ice. Using DFT computed IR spectra to identify photoproducts and PAH cations, we tentatively identify the production of specific alcohols [PAH(OH) {sub n} ] and quinones [PAH(O) {sub n} ] for all PAH:H{sub 2}O ices considered here. Little evidence is found for hydrogenation at 14 K, consistent with the findings of Gudipati and Yang. Addition of O and OH to the parent PAH is the dominant photochemical reaction, but PAH erosion to smaller PAHs (producing CO{sub 2} and H{sub 2}CO) is also important. DFT spectra are used to assess the contribution of PAH-related species to interstellar absorption features from 5 to 9 μm. The case is made that PAH cations are important contributors to the C2 component and PAH(OH) {sub n} and PAH(O) {sub n} to the C5 component described by Boogert et al. Thus, interstellar ices should contain neutral and ionized PAHs, alcohols, ketones and quinones at the ∼2%-4% level relative to H{sub 2}O. PAHs, their photoproducts, and ion-mediated processes should therefore be considered when modeling interstellar ice processes.

  19. Analysis of the Effect of Water Activity on Ice Formation Using a New Theory of Nucleation

    Science.gov (United States)

    Barahona, Donifan

    2013-01-01

    In this work a new theory of nucleation is developed and used to investigate the effect of water activity on the formation of ice within super-cooled droplets. The new theory is based on a novel concept where the interface is assumed to be made of liquid molecules trapped by the solid matrix. Using this concept new expressions are developed for the critical ice germ size and the nucleation work, with explicit dependencies on temperature and water activity. However unlike previous approaches, the new theory does not depend on the interfacial tension between liquid and ice. Comparison against experimental results shows that the new theory is able to reproduce the observed effect of water activity on nucleation rate and freezing temperature. It allows for the first time a theoretical derivation of the constant shift in water activity between melting and nucleation. The new theory offers a consistent thermodynamic view of ice nucleation, simple enough to be applied in atmospheric models of cloud formation.

  20. Estimating Past Temperature Change in Antarctica Based on Ice Core Stable Water Isotope Diffusion

    Science.gov (United States)

    Kahle, E. C.; Markle, B. R.; Holme, C.; Jones, T. R.; Steig, E. J.

    2017-12-01

    The magnitude of the last glacial-interglacial transition is a key target for constraining climate sensitivity on long timescales. Ice core proxy records and general circulation models (GCMs) both provide insight on the magnitude of climate change through the last glacial-interglacial transition, but appear to provide different answers. In particular, the magnitude of the glacial-interglacial temperature change reconstructed from East Antarctic ice-core water-isotope records is greater ( 9 degrees C) than that from most GCM simulations ( 6 degrees C). A possible source of this difference is error in the linear-scaling of water isotopes to temperature. We employ a novel, nonlinear temperature-reconstruction technique using the physics of water-isotope diffusion to infer past temperature. Based on new, ice-core data from the South Pole, this diffusion technique suggests East Antarctic temperature change was smaller than previously thought. We are able to confirm this result using a simple, water-isotope fractionation model to nonlinearly reconstruct temperature change at ice core locations across Antarctica based on combined oxygen and hydrogen isotope ratios. Both methods produce a temperature change of 6 degrees C for South Pole, agreeing with GCM results for East Antarctica. Furthermore, both produce much larger changes in West Antarctica, also in agreement with GCM results and independent borehole thermometry. These results support the fidelity of GCMs in simulating last glacial maximum climate, and contradict the idea, based on previous work, that the climate sensitivity of current GCMs is too low.

  1. UV/Vis spectroscopy of C60 embedded in water ice

    DEFF Research Database (Denmark)

    Cuylle, Steven; Linnartz, Harold; Thrower, John

    2012-01-01

    Electronic solid state spectra are recorded for C60 embedded in 40 K water ice using broad band direct absorption spectroscopy, and assigned with reference to existing matrix data. The results are interesting in view of the recent gas phase detection of fullerenes in the interstellar medium...

  2. High laser-fluence deposition of organic materials in water ice matrices by ''MAPLE''

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Rodrigo, K.; Schou, Jørgen

    2005-01-01

    Matrix assisted pulsed laser evaporation (MAPLE) is a deposition technique for organic material. Water ice was used as a matrix for the biotechnologically important guest material, polyethylene glycol (PEG), for concentrations from 0.5 to 4 wt.%. The target was irradiated with 6 ns laser pulses...

  3. Oxo Crater on (1) Ceres: Geological History and the Role of Water-ice

    Energy Technology Data Exchange (ETDEWEB)

    Nathues, A.; Platz, T.; Hoffmann, M.; Thangjam, G.; Le Corre, L.; Reddy, V. [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Goettingen (Germany); Cloutis, E. A.; Applin, D. M. [University of Winnipeg, Winnipeg, MB R3B 2E9 (Canada); Mengel, K. [IELF, TU Clausthal, Adolph-Roemer-Straße 2A, D-38678 Clausthal-Zellerfeld (Germany); Protopapa, S. [University of Maryland, Department of Astronomy, College Park, MD 20742 (United States); Takir, D. [SETI Institute, Mountain View, CA 94043 (United States); Preusker, F. [German Aerospace Center (DLR), Institute of Planetary Research, D-12489 Berlin (Germany); Schmidt, B. E. [Georgia Institute of Technology, Atlanta, GA (United States); Russell, C. T., E-mail: nathues@mps.mpg.de [Institute of Geophysics and Planetary Physics, Dept. of Earth, Planetary and Space Sciences, University of California Los Angeles, Los Angeles, CA (United States)

    2017-09-01

    Dwarf planet Ceres (∅ ∼ 940 km) is the largest object in the main asteroid belt. Investigations suggest that Ceres is a thermally evolved, volatile-rich body with potential geological activity, a body that was never completely molten, but one that possibly partially differentiated into a rocky core and an ice-rich mantle, and may contain remnant internal liquid water. Thermal alteration and the infall of exogenic material contribute to producing a (dark) carbonaceous chondritic-like surface containing ammoniated phyllosilicates. Here we report imaging and spectroscopic analyses of data on the bright Oxo crater derived from the Framing Camera and the Visible and Infrared Spectrometer on board the Dawn spacecraft. We confirm that the transitional complex crater Oxo (∅ ∼ 9 km) exhibits exposed surface water-ice. We show that this water-ice-rich material is associated exclusively with two lobate deposits at pole-facing scarps, deposits that also contain carbonates and admixed phyllosilicates. Due to Oxo’s location at −4802 m below the cerean reference ellipsoid and its very young age of only 190 ka (1 σ : +100 ka, −70 ka), Oxo is predestined for ongoing water-ice sublimation.

  4. COMPONENT DEVELOPMENT NEEDS FOR THE HYBRID SULFUR ELECTROLYZER

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D; Hector Colon-Mercado, H; Mark Elvington, M

    2008-05-30

    Fiscal year 2008 studies in electrolyzer component development have focused on the characterization of membrane electrode assemblies (MEA) after performance tests in the single cell electrolyzer, evaluation of electrocatalysts and membranes using a small scale electrolyzer and evaluating the contribution of individual cell components to the overall electrochemical performance. Scanning electron microscopic (SEM) studies of samples taken from MEAs testing in the SRNL single cell electrolyzer test station indicates a sulfur-rich layer forms between the cathode catalyst layer and the membrane. Based on a review of operating conditions for each of the MEAs evaluated, we conclude that the formation of the layer results from the reduction of sulfur dioxide as it passes through the MEA and reaches the catalyst layer at the cathode-membrane interface. Formation of the sulfur rich layer results in partial delamination of the cathode catalyst layer leading to diminished performance. Furthermore we believe that operating the electrolyzer at elevated pressure significantly increases the rate of formation due to increased adsorption of hydrogen on the internal catalyst surface. Thus, identification of a membrane that exhibits much lower transport of sulfur dioxide is needed to reduce the quantity of sulfur dioxide that reaches the cathode catalyst and is reduced to produce the sulfur-rich layer. Three candidate membranes are currently being evaluated that have shown promise from preliminary studies, (1) modified Nafion{reg_sign}, (2) polybenzimidazole (PBI), and (3) sulfonated Diels Alder polyphenylene (SDAPP). Testing examined the activity for the sulfur dioxide oxidation of platinum (Pt) and platinum-alloy catalysts in 30 wt% sulfuric acid solution. Linear sweep voltammetry showed an increase in activity when catalysts in which Pt is alloyed with non-noble transition metals such as cobalt and chromium. However when Pt is alloyed with noble metals, such as iridium or ruthenium

  5. Thermodynamical effects accompanied freezing of two water layers separated by sea ice sheet

    Science.gov (United States)

    Bogorodsky, Petr; Marchenko, Aleksey

    2014-05-01

    The process of melt pond freezing is very important for generation of sea ice cover thermodynamic and mass balance during winterperiod. However, due to significant difficulties of field measurements the available data of model estimations still have no instrumental confirmation. In May 2009 the authors carried out laboratory experiment on freezing of limited water volume in the University Centre in Svalbard ice tank. In the course of experiment fresh water layer of 27.5 cm thickness at freezing point poured on the 24 cm sea ice layer was cooled during 50 hours at the temperature -10º C and then once again during 60 hours at -20º C. For revealing process typical characteristics the data of continuous measurements of temperature and salinity in different phases were compared with data of numerical computations obtained with thermodynamic model which was formulated in the frames of 1-D equation system (infinite extension of water freezing layer) and adapted to laboratory conditions. The known surprise of the experiment became proximity of calculated and measured estimates of process dynamics that confirmed the adequacy of the problem mathematical statement (excluding probably process finale stage). This effect can be explained by formation of cracks on the upper layer of ice at sharp decreases of air temperature, which temporary compensated hydrostatic pressure growth during freezing of closed water volume. Another compensated mechanism can be migration of brine through the lower layer of ice under influence of vertical pressure gradient and also rejection of gas dissolved in water which increased its compressibility. During 110 hours cooling thickness of water layer between ice layers reduced approximately to 2 cm. According to computations this layer is not chilled completely but keeps as thin brine interlayer within ice body whose thickness (about units of mm) is determined by temperature fluctuations of cooled surface. Nevertheless, despite good coincidence of

  6. Microwave radiometric aircraft observations of the Fabry-Perot interference fringes of an ice-water system

    Science.gov (United States)

    Harrington, R. F.; Swift, C. T.; Fedors, J. C.

    1980-01-01

    Airborne stepped-frequency microwave radiometer (SFMR) observations of the Fabry-Perot interference fringes of ice-water systems are discussed. The microwave emissivity at normal incidence of a smooth layered dielectric medium over a semi-infinite dielectric medium is examined for the case of ice over water as a function of ice thickness and attenuation coefficient, and the presence of quarter-wavelength oscillations in emissivity as the ice thickness and frequency are varied is pointed out. Experimental observations of pronounced quarter-wavelength oscillations in radiometric brightness temperature due to the Fabry-Perot interference fringes over smooth sea ice and lake ice varying in roughness as the radiometer frequencies were scanned are then presented.

  7. Observed vulnerability of Filchner-Ronne Ice Shelf to wind-driven inflow of warm deep water

    Science.gov (United States)

    Darelius, E.; Fer, I.; Nicholls, K. W.

    2016-01-01

    The average rate of melting at the base of the large Filchner-Ronne Ice Shelf in the southern Weddell Sea is currently low, but projected to increase dramatically within the next century. In a model study, melt rates increase as changing ice conditions cause a redirection of a coastal current, bringing warm water of open ocean origin through the Filchner Depression and into the Filchner Ice Shelf cavity. Here we present observations from near Filchner Ice Shelf and from the Filchner Depression, which show that pulses of warm water already arrive as far south as the ice front. This southward heat transport follows the eastern flank of the Filchner Depression and is found to be directly linked to the strength of a wind-driven coastal current. Our observations emphasize the potential sensitivity of Filchner-Ronne Ice Shelf melt rates to changes in wind forcing. PMID:27481659

  8. Graphitic Carbon Nitride as a Catalyst Support in Fuel Cells and Electrolyzers

    International Nuclear Information System (INIS)

    Mansor, Noramalina; Miller, Thomas S.; Dedigama, Ishanka; Jorge, Ana Belen; Jia, Jingjing; Brázdová, Veronika; Mattevi, Cecilia; Gibbs, Chris; Hodgson, David; Shearing, Paul R.; Howard, Christopher A.; Corà, Furio; Shaffer, Milo; Brett, Daniel J.L.

    2016-01-01

    Highlights: • Graphitic carbon nitride (gCN) describes many materials with different structures. • gCNs can exhibit excellent mechanical, chemical and thermal resistance. • A major obstacle for pure gCN catalyst supports is limited electronic conductivity. • Composite/Hybrid gCN structures show excellent performance as catalyst supports. • gCNs have great potential for use in fuel calls and water electrolyzers. - Abstract: Electrochemical power sources, such as polymer electrolyte membrane fuel cells (PEMFCs), require the use of precious metal catalysts which are deposited as nanoparticles onto supports in order to minimize their mass loading and therefore cost. State-of-the-art/commercial supports are based on forms of carbon black. However, carbon supports present disadvantages including corrosion in the operating fuel cell environment and loss of catalyst activity. Here we review recent work examining the potential of different varieties of graphitic carbon nitride (gCN) as catalyst supports, highlighting their likely benefits, as well as the challenges associated with their implementation. The performance of gCN and hybrid gCN-carbon materials as PEMFC electrodes is discussed, as well as their potential for use in alkaline systems and water electrolyzers. We illustrate the discussion with examples taken from our own recent studies.

  9. Theoretical Analysis on Marangoni-driven Cavity Formation in Ice during In Situ Burning of Oil Spills in Ice-infested Waters

    Science.gov (United States)

    Farmahini Farahani, H.; Jomaas, G.; Rangwala, A. S.

    2017-12-01

    In situ burning, intentional burning of discharged oil on the water surface, is a promising response method to oil spill accidents in the Arctic. However, burning of the oil adjacent to ice bodies creates a lateral cavity in the ice. As a result of the cavity formation the removal efficiency which is a key success criterion for in situ burning operation will decrease. The formation of lateral cavities are noticed recently and only a few experimental studies have addressed them. These experiments have shown lateral cavities with a length of severe horizontal temperature gradient which in turn generates a Marangoni flow from hot to cold regions. This is found to be the dominant heat transfer mechanism that is providing the heat for the ice to melt. Here, we introduce an order of magnitude analysis on the governing equations of the ice melting problem to estimate the penetration length of a burning oil near ice. This correlation incorporates the flame heat feedback with the surface flow driven by Marangoni convection. The melting energy continuity is also included in the analysis to complete the energy transfer cycle that leads to melting of the ice. The comparison between this correlation and the existing experimental data shows a very good agreement. Therefore, this correlation can be used to estimate the penetration length for burning of an actual spill and can be applied towards improved guidelines of burning adjacent to ice bodies, so as to enhance the chances for successful implantation of in situ burning.

  10. CHEMICAL PROCESSING OF PURE AMMONIA AND AMMONIA-WATER ICES INDUCED BY HEAVY IONS

    Energy Technology Data Exchange (ETDEWEB)

    Bordalo, V.; Da Silveira, E. F. [Departamento de Fisica/Laboratorio do Acelerador Van de Graaff, Pontificia Universidade Catolica do Rio de Janeiro, Rua Marques de S. Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil); Lv, X. Y.; Domaracka, A.; Rothard, H.; Boduch, P. [Centre de Recherche sur les Ions, les Materiaux et la Photonique (CEA/CNRS/ENSICAEN/Universite de Caen-Basse Normandie), CIMAP-CIRIL-GANIL, Boulevard Henri Becquerel, BP 5133, F-14070 Caen Cedex 05 (France); Seperuelo Duarte, E., E-mail: vbordalo@fis.puc-rio.br [Grupo de Fisica e Astronomia, Instituto Federal do Rio de Janeiro, Rua Lucio Tavares 1045, 26530-060 Nilopolis, RJ (Brazil)

    2013-09-10

    Cosmic rays are possibly the main agents to prevent the freeze-out of molecules onto grain surfaces in cold dense clouds. Ammonia (NH{sub 3}) is one of the most abundant molecules present in dust ice mantles, with a concentration of up to 15% relative to water (H{sub 2}O). FTIR spectroscopy is used to monitor pure NH{sub 3} and NH{sub 3}-H{sub 2}O ice samples as they are irradiated with Ni and Zn ion beams (500-600 MeV) at GANIL/France. New species, such as hydrazine (N{sub 2}H{sub 4}), diazene (N{sub 2}H{sub 2} isomers), molecular hydrogen (H{sub 2}), and nitrogen (N{sub 2}) were identified after irradiation of pure NH{sub 3} ices. Nitrous oxide (N{sub 2}O), nitrogen oxide (NO), nitrogen dioxide (NO{sub 2}), and hydroxylamine (NH{sub 2}OH) are some of the products of the NH{sub 3}-H{sub 2}O ice radiolysis. The spectral band at 6.85 {mu}m was observed after irradiation of both types of ice. Besides the likely contribution of ammonium (NH{sub 4}{sup +}) and amino (NH{sub 2}) radicals, data suggest a small contribution of NH{sub 2}OH to this band profile after high fluences of irradiation of NH{sub 3}-H{sub 2}O ices. The spectral shift of the NH{sub 3} ''umbrella'' mode (9.3 {mu}m) band is parameterized as a function of NH{sub 3}/H{sub 2}O ratio in amorphous ices. Ammonia and water destruction cross-sections are obtained, as well as the rate of NH{sub 3}-H{sub 2}O (1:10) ice compaction, measured by the OH dangling bond destruction cross-section. Ammonia destruction is enhanced in the presence of H{sub 2}O in the ice and a power law relationship between stopping power and NH{sub 3} destruction cross-section is verified. Such results may provide relevant information for the evolution of molecular species in dense molecular clouds.

  11. Survival of organic materials in hypervelocity impacts of ice on sand, ice, and water in the laboratory.

    Science.gov (United States)

    Burchell, Mark J; Bowden, Stephen A; Cole, Michael; Price, Mark C; Parnell, John

    2014-06-01

    The survival of organic molecules in shock impact events has been investigated in the laboratory. A frozen mixture of anthracene and stearic acid, solvated in dimethylsulfoxide (DMSO), was fired in a two-stage light gas gun at speeds of ~2 and ~4 km s(-1) at targets that included water ice, water, and sand. This involved shock pressures in the range of 2-12 GPa. It was found that the projectile materials were present in elevated quantities in the targets after impact and in some cases in the crater ejecta as well. For DMSO impacting water at 1.9 km s(-1) and 45° incidence, we quantify the surviving fraction after impact as 0.44±0.05. This demonstrates successful transfer of organic compounds from projectile to target in high-speed impacts. The range of impact speeds used covers that involved in impacts of terrestrial meteorites on the Moon, as well as impacts in the outer Solar System on icy bodies such as Pluto. The results provide laboratory evidence that suggests that exogenous delivery of complex organic molecules from icy impactors is a viable source of such material on target bodies.

  12. Monitoring Forsmark. Snow depth, snow water content and ice cover during the winter 2010/2011

    International Nuclear Information System (INIS)

    Wass, Eva

    2011-07-01

    Snow depth and ice cover have been measured and observed during the winter 2010/2011. This type of measurements started in the winter 2002/2003 and has been ongoing since then. In addition to these parameters, the water content of the snow was calculated at each measurement occasion from the weight of a snow sample. Measurements and observations were conducted on a regular basis from the beginning of November 2010 until the middle of April 2011. A persistent snow cover was established in the end of November 2010 and remained until the beginning of April 2011 at the station with longest snow cover duration. The period of ice cover was 160 days in Lake Eckarfjaerden, whereas the sea bay at SFR was ice covered for 135 days

  13. Monitoring Forsmark. Snow depth, snow water content and ice cover during the winter 2010/2011

    Energy Technology Data Exchange (ETDEWEB)

    Wass, Eva (Geosigma AB (Sweden))

    2011-07-15

    Snow depth and ice cover have been measured and observed during the winter 2010/2011. This type of measurements started in the winter 2002/2003 and has been ongoing since then. In addition to these parameters, the water content of the snow was calculated at each measurement occasion from the weight of a snow sample. Measurements and observations were conducted on a regular basis from the beginning of November 2010 until the middle of April 2011. A persistent snow cover was established in the end of November 2010 and remained until the beginning of April 2011 at the station with longest snow cover duration. The period of ice cover was 160 days in Lake Eckarfjaerden, whereas the sea bay at SFR was ice covered for 135 days

  14. SHARAD detection and characterization of subsurface water ice deposits in Utopia Planitia, Mars

    Science.gov (United States)

    Stuurman, C. M.; Osinski, G. R.; Holt, J. W.; Levy, J. S.; Brothers, T. C.; Kerrigan, M.; Campbell, B. A.

    2016-09-01

    Morphological analyses of Utopia Planitia, Mars, have led to the hypothesis that the region contains a substantial amount of near-surface ice. This paper tests this hypothesis using ground-penetrating radar techniques. We have identified an expansive radar reflective region spanning approximately 375,000 km2 in SHAllow RADar (SHARAD) data over western Utopia Planitia. The SHARAD reflective regions coincides with high densities of scalloped depressions and polygonal terrain. The reflectors are associated with layered mesas ˜80-170 m thick. We find a value of 2.8 ± 0.8 for the dielectric constant of the material overlying the reflectors. This work finds that the dielectric constant is consistent with a mixture of ice, air, and dust, containing a water ice volume up to 14,300 km3 in this unit.

  15. Synoptic Traveling Weather Systems on Mars: Effects of Radiatively-Active Water Ice Clouds

    Science.gov (United States)

    Hollingsworth, Jeffery; Kahre, Melinda; Haberle, Robert; Urata, Richard

    2017-01-01

    Atmospheric aerosols on Mars are critical in determining the nature of its thermal structure, its large-scale circulation, and hence the overall climate of the planet. We conduct multi-annual simulations with the latest version of the NASA Ames Mars global climate model (GCM), gcm2.3+, that includes a modernized radiative-transfer package and complex water-ice cloud microphysics package which permit radiative effects and interactions of suspended atmospheric aerosols (e.g., water ice clouds, water vapor, dust, and mutual interactions) to influence the net diabatic heating. Results indicate that radiatively active water ice clouds profoundly affect the seasonal and annual mean climate. The mean thermal structure and balanced circulation patterns are strongly modified near the surface and aloft. Warming of the subtropical atmosphere at altitude and cooling of the high latitude atmosphere at low levels takes place, which increases the mean pole-to-equator temperature contrast (i.e., "baroclinicity"). With radiatively active water ice clouds (RAC) compared to radiatively inert water ice clouds (nonRAC), significant changes in the intensity of the mean state and forced stationary Rossby modes occur, both of which affect the vigor and intensity of traveling, synoptic period weather systems.Such weather systems not only act as key agents in the transport of heat and momentum beyond the extent of the Hadley circulation, but also the transport of trace species such as water vapor, water ice-clouds, dust and others. The northern hemisphere (NH) forced Rossby waves and resultant wave train are augmented in the RAC case: the modes are more intense and the wave train is shifted equatorward. Significant changes also occur within the subtropics and tropics. The Rossby wave train sets up, combined with the traveling synoptic period weather systems (i.e., cyclones and anticyclones), the geographic extent of storm zones (or storm tracks) within the NH. A variety of circulation

  16. Bio-optical properties of Arctic drift ice and surface waters north of Svalbard from winter to spring

    Science.gov (United States)

    Kowalczuk, Piotr; Meler, Justyna; Kauko, Hanna M.; Pavlov, Alexey K.; Zabłocka, Monika; Peeken, Ilka; Dybwad, Christine; Castellani, Giulia; Granskog, Mats A.

    2017-06-01

    We have quantified absorption by CDOM, aCDOM(λ), particulate matter, ap(λ), algal pigments, aph(λ), and detrital material, aNAP(λ), coincident with chlorophyll a in sea ice and surface waters in winter and spring 2015 in the Arctic Ocean north of Svalbard. The aCDOM(λ) was low in contrast to other regions of the Arctic Ocean, while ap(λ) has the largest contribution to absorption variability in sea ice and surface waters. ap(443) was 1.4-2.8 times and 1.3-1.8 times higher than aCDOM(443) in surface water and sea ice, respectively. aph(λ) contributed 90% and 81% to ap(λ), in open leads and under-ice waters column, and much less (53%-74%) in sea ice, respectively. Both aCDOM(λ) and ap(λ) followed closely the vertical distribution of chlorophyll a in sea ice and the water column. We observed a tenfold increase of the chlorophyll a concentration and nearly twofold increase in absorption at 443 nm in sea ice from winter to spring. The aCDOM(λ) dominated the absorption budget in the UV both in sea ice and surface waters. In the visible range, absorption was dominated by aph(λ), which contributed more than 50% and aCDOM(λ), which contributed 43% to total absorption in water column. Detrital absorption contributed significantly (33%) only in surface ice layer. Algae dynamics explained more than 90% variability in ap(λ) and aph(λ) in water column, but less than 70% in the sea ice. This study presents detailed absorption budget that is relevant for modeling of radiative transfer and primary production.

  17. Using polyatomic primary ions to probe an amino acid and a nucleic base in water ice

    Energy Technology Data Exchange (ETDEWEB)

    Conlan, X.A. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)]. E-mail: x.conlan@postgrad.manchester.ac.uk; Biddulph, G.X. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)]. E-mail: G.Biddulph@postgrad.manchester.ac.uk; Lockyer, N.P. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom); Vickerman, J.C. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)]. E-mail: John.Vickerman@manchester.ac.uk

    2006-07-30

    In this study on pure water ice, we show that protonated water species [H{sub 2}O] {sub n}H{sup +} are more prevalent than (H{sub 2}O) {sub n} {sup +} ions after bombardment by Au{sup +} monoatomic and Au{sub 3} {sup +} and C{sub 60} {sup +} polyatomic projectiles. This data also reveals significant differences in water cluster yields under bombardment by these three projectiles. The amino acid alanine and the nucleic base adenine in solution have been studied and have been shown to have an effect on the water cluster ion yields observed using an Au{sub 3} {sup +} ion beam.

  18. Archival processes of the water stable isotope signal in East Antarctic ice cores

    Science.gov (United States)

    Casado, Mathieu; Landais, Amaelle; Picard, Ghislain; Münch, Thomas; Laepple, Thomas; Stenni, Barbara; Dreossi, Giuliano; Ekaykin, Alexey; Arnaud, Laurent; Genthon, Christophe; Touzeau, Alexandra; Masson-Delmotte, Valerie; Jouzel, Jean

    2018-05-01

    The oldest ice core records are obtained from the East Antarctic Plateau. Water isotopes are key proxies to reconstructing past climatic conditions over the ice sheet and at the evaporation source. The accuracy of climate reconstructions depends on knowledge of all processes affecting water vapour, precipitation and snow isotopic compositions. Fractionation processes are well understood and can be integrated in trajectory-based Rayleigh distillation and isotope-enabled climate models. However, a quantitative understanding of processes potentially altering snow isotopic composition after deposition is still missing. In low-accumulation sites, such as those found in East Antarctica, these poorly constrained processes are likely to play a significant role and limit the interpretability of an ice core's isotopic composition. By combining observations of isotopic composition in vapour, precipitation, surface snow and buried snow from Dome C, a deep ice core site on the East Antarctic Plateau, we found indications of a seasonal impact of metamorphism on the surface snow isotopic signal when compared to the initial precipitation. Particularly in summer, exchanges of water molecules between vapour and snow are driven by the diurnal sublimation-condensation cycles. Overall, we observe in between precipitation events modification of the surface snow isotopic composition. Using high-resolution water isotopic composition profiles from snow pits at five Antarctic sites with different accumulation rates, we identified common patterns which cannot be attributed to the seasonal variability of precipitation. These differences in the precipitation, surface snow and buried snow isotopic composition provide evidence of post-deposition processes affecting ice core records in low-accumulation areas.

  19. Response of faults to climate-driven changes in ice and water volumes on Earth's surface.

    Science.gov (United States)

    Hampel, Andrea; Hetzel, Ralf; Maniatis, Georgios

    2010-05-28

    Numerical models including one or more faults in a rheologically stratified lithosphere show that climate-induced variations in ice and water volumes on Earth's surface considerably affect the slip evolution of both thrust and normal faults. In general, the slip rate and hence the seismicity of a fault decreases during loading and increases during unloading. Here, we present several case studies to show that a postglacial slip rate increase occurred on faults worldwide in regions where ice caps and lakes decayed at the end of the last glaciation. Of note is that the postglacial amplification of seismicity was not restricted to the areas beneath the large Laurentide and Fennoscandian ice sheets but also occurred in regions affected by smaller ice caps or lakes, e.g. the Basin-and-Range Province. Our results do not only have important consequences for the interpretation of palaeoseismological records from faults in these regions but also for the evaluation of the future seismicity in regions currently affected by deglaciation like Greenland and Antarctica: shrinkage of the modern ice sheets owing to global warming may ultimately lead to an increase in earthquake frequency in these regions.

  20. Consequences of long-distance swimming and travel over deep-water pack ice for a female polar bear during a year of extreme sea ice retreat

    Science.gov (United States)

    Durner, George M.; Whiteman, J.P.; Harlow, H.J.; Amstrup, Steven C.; Regehr, E.V.; Ben-David, M.

    2011-01-01

    Polar bears (Ursus maritimus) prefer to live on Arctic sea ice but may swim between ice floes or between sea ice and land. Although anecdotal observations suggest that polar bears are capable of swimming long distances, no data have been available to describe in detail long distance swimming events or the physiological and reproductive consequences of such behavior. Between an initial capture in late August and a recapture in late October 2008, a radio-collared adult female polar bear in the Beaufort Sea made a continuous swim of 687 km over 9 days and then intermittently swam and walked on the sea ice surface an additional 1,800 km. Measures of movement rate, hourly activity, and subcutaneous and external temperature revealed distinct profiles of swimming and walking. Between captures, this polar bear lost 22% of her body mass and her yearling cub. The extraordinary long distance swimming ability of polar bears, which we confirm here, may help them cope with reduced Arctic sea ice. Our observation, however, indicates that long distance swimming in Arctic waters, and travel over deep water pack ice, may result in high energetic costs and compromise reproductive fitness.

  1. Atypical water lattices and their possible relevance to the amorphous ices: A density functional study

    Science.gov (United States)

    Anick, David J.

    2013-04-01

    Of the fifteen known crystalline forms of ice, eleven consist of a single topologically connected hydrogen bond network with four H-bonds at every O. The other four, Ices VI-VIII and XV, consist of two topologically connected networks, each with four H-bonds at every O. The networks interpenetrate but do not share H-bonds. This article presents two new periodic water lattice families whose topological connectivity is "atypical": they consist of many two-dimensional layers that share no H-bonds. Layers are held together only by dispersion forces. Within each layer there are still four H-bonds at each O. Called "Hexagonal Bilayer Water" (HBW) and "Pleated Sheet Water" (PSW), they have computed densities of about 1.1 g/mL and 1.3 g/mL respectively, and nearest neighbor O-coordination is 4.5 to 5.5 and 6 to 8 respectively. Using density functional theory (BLYP-D/TZVP), various proton ordered forms of HBW and PSW are optimized and categorized. There are simple pathways connecting Ice-Ih to HBW and HBW to PSW. Their computed properties suggest similarities to the high density and very high density amorphous ices (HDA and VHDA) respectively. It is unknown whether HDA, VHDA, and Low Density Amorphous Ice (LDA) are fully disordered glasses down to the molecular level, or whether there is some short-range local order. Based on estimated radial distribution functions (RDFs), one proton ordered form of HBW matches HDA best. The idea is explored that HDA could contain islands with this underlying structure, and likewise, that VHDA could contain regions of PSW. A "microlattice model version 1" (MLM1) is presented as a device to compare key experimental data on the amorphous ices with these atypical structures and with a microlattice form of Ice-XI for LDA. Resemblances are found with the amorphs' RDFs, densities, Raman spectra, and transition behaviors. There is not enough information in the static models to assign either a microlattice structure or a partial microlattice

  2. Laboratory determination of the infrared band strengths of pyrene frozen in water ice: Implications for the composition of interstellar ices

    Energy Technology Data Exchange (ETDEWEB)

    Hardegree-Ullman, E. E. [New York Center for Astrobiology and Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States); Gudipati, M. S.; Werner, M. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Boogert, A. C. A. [Infrared Processing and Analysis Center, Mail Code 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Lignell, H. [Department of Chemistry, University of California Irvine, Irvine, CA 92697-2025 (United States); Allamandola, L. J. [Space Science Division, Mail Stop 245-6, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Stapelfeldt, K. R., E-mail: hardee@rpi.edu, E-mail: gudipati@jpl.nasa.gov [NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory, Code 667, Greenbelt, MD 20771 (United States)

    2014-04-01

    Broad infrared emission features (e.g., at 3.3, 6.2, 7.7, 8.6, and 11.3 μm) from the gas phase interstellar medium have long been attributed to polycyclic aromatic hydrocarbons (PAHs). A significant portion (10%-20%) of the Milky Way's carbon reservoir is locked in PAH molecules, which makes their characterization integral to our understanding of astrochemistry. In molecular clouds and the dense envelopes and disks of young stellar objects (YSOs), PAHs are expected to be frozen in the icy mantles of dust grains where they should reveal themselves through infrared absorption. To facilitate the search for frozen interstellar PAHs, laboratory experiments were conducted to determine the positions and strengths of the bands of pyrene mixed with H{sub 2}O and D{sub 2}O ices. The D{sub 2}O mixtures are used to measure pyrene bands that are masked by the strong bands of H{sub 2}O, leading to the first laboratory determination of the band strength for the CH stretching mode of pyrene in water ice near 3.25 μm. Our infrared band strengths were normalized to experimentally determined ultraviolet band strengths, and we find that they are generally ∼50% larger than those reported by Bouwman et al. based on theoretical strengths. These improved band strengths were used to reexamine YSO spectra published by Boogert et al. to estimate the contribution of frozen PAHs to absorption in the 5-8 μm spectral region, taking into account the strength of the 3.25 μm CH stretching mode. It is found that frozen neutral PAHs contain 5%-9% of the cosmic carbon budget and account for 2%-9% of the unidentified absorption in the 5-8 μm region.

  3. Photochemistry of Coronene in Cosmic Water Ice Analogs at Different Concentrations

    Energy Technology Data Exchange (ETDEWEB)

    De Barros, A. L. F. [Departamento de Física, Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Av. Maracanã 229, 20271-110 Rio de Janeiro, RJ (Brazil); Mattioda, A. L.; Ricca, A.; Cruz-Diaz, G.A.; Allamandola, L. J. [NASA Ames Research Center, Mail Stop 245-6, Moffett Field, CA 94035-1000 (United States)

    2017-10-20

    This work presents the photochemistry of ultraviolet (UV) irradiated coronene in water ices at 15 K studied using mid-infrared Fourier transform (FTIR) spectroscopy for C{sub 24}H{sub 12}:H{sub 2}O at concentrations of (1:50), (1:150), (1:200), (1:300), and (1:400). Previous UV irradiation studies of anthracene:H{sub 2}O, pyrene:H{sub 2}O, and benzo[ghi]perylene:H{sub 2}O ices at 15 K have shown that aromatic alcohols and ketones, as well as CO{sub 2} and H{sub 2}CO, are formed at very low temperatures. Likewise, here, in addition to the coronene cation, hydroxy-, keto-, and protonated coronene (coronene H{sup +}) are formed. The rate constants for the decay of neutral coronene and for the formation of photoproducts have been derived. It is shown that Polycyclic Aromatic Hydrocarbons (PAHs) and their UV induced PAH:H{sub 2}O photoproducts have mid-infrared spectroscopic signatures in the 5–8 μ m region that can contribute to the interstellar ice components described by Boogert et al. as C1–C5. Our results suggest that oxygenated and hydrogenated PAHs could be in UV-irradiated regions of the interstellar medium where water-rich ices are important.

  4. Photochemistry of Coronene in Cosmic Water Ice Analogs at Different Concentrations

    Science.gov (United States)

    de Barros, A. L. F.; Mattioda, A. L.; Ricca, A.; Cruz-Diaz, G. A.; Allamandola, L. J.

    2017-10-01

    This work presents the photochemistry of ultraviolet (UV) irradiated coronene in water ices at 15 K studied using mid-infrared Fourier transform (FTIR) spectroscopy for C24H12:H2O at concentrations of (1:50), (1:150), (1:200), (1:300), and (1:400). Previous UV irradiation studies of anthracene:H2O, pyrene:H2O, and benzo[ghi]perylene:H2O ices at 15 K have shown that aromatic alcohols and ketones, as well as CO2 and H2CO, are formed at very low temperatures. Likewise, here, in addition to the coronene cation, hydroxy-, keto-, and protonated coronene (coronene H+) are formed. The rate constants for the decay of neutral coronene and for the formation of photoproducts have been derived. It is shown that Polycyclic Aromatic Hydrocarbons (PAHs) and their UV induced PAH:H2O photoproducts have mid-infrared spectroscopic signatures in the 5-8 μm region that can contribute to the interstellar ice components described by Boogert et al. as C1-C5. Our results suggest that oxygenated and hydrogenated PAHs could be in UV-irradiated regions of the interstellar medium where water-rich ices are important.

  5. Photochemistry of Coronene in Cosmic Water Ice Analogs at Different Concentrations

    International Nuclear Information System (INIS)

    De Barros, A. L. F.; Mattioda, A. L.; Ricca, A.; Cruz-Diaz, G.A.; Allamandola, L. J.

    2017-01-01

    This work presents the photochemistry of ultraviolet (UV) irradiated coronene in water ices at 15 K studied using mid-infrared Fourier transform (FTIR) spectroscopy for C 24 H 12 :H 2 O at concentrations of (1:50), (1:150), (1:200), (1:300), and (1:400). Previous UV irradiation studies of anthracene:H 2 O, pyrene:H 2 O, and benzo[ghi]perylene:H 2 O ices at 15 K have shown that aromatic alcohols and ketones, as well as CO 2 and H 2 CO, are formed at very low temperatures. Likewise, here, in addition to the coronene cation, hydroxy-, keto-, and protonated coronene (coronene H + ) are formed. The rate constants for the decay of neutral coronene and for the formation of photoproducts have been derived. It is shown that Polycyclic Aromatic Hydrocarbons (PAHs) and their UV induced PAH:H 2 O photoproducts have mid-infrared spectroscopic signatures in the 5–8 μ m region that can contribute to the interstellar ice components described by Boogert et al. as C1–C5. Our results suggest that oxygenated and hydrogenated PAHs could be in UV-irradiated regions of the interstellar medium where water-rich ices are important.

  6. Vertical distribution and diel vertical migration of krill beneath snow-covered ice and in ice-free waters

    KAUST Repository

    Vestheim, Hege; Rø stad, Anders; Klevjer, Thor A.; Solberg, Ingrid; Kaartvedt, Stein

    2013-01-01

    A bottom mounted upward looking Simrad EK60 120-kHz echo sounder was used to study scattering layers (SLs) and individuals of the krill Meganyctiphanes norvegica. The mooring was situated at 150-m depth in the Oslofjord, connected with an onshore cable for power and transmission of digitized data. Records spanned 5 months from late autumn to spring. A current meter and CTD was associated with the acoustic mooring and a shore-based webcam monitored ice conditions in the fjord. The continuous measurements were supplemented with intermittent krill sampling campaigns and their physical and biological environment.The krill carried out diel vertical migration (DVM) throughout the winter, regardless of the distribution of potential prey. The fjord froze over in mid-winter and the daytime distribution of a mid-water SL of krill immediately became shallower associated with snow fall after freezing, likely related to reduction of light intensities. Still, a fraction of the population always descended all the way to the bottom, so that the krill population by day seemed to inhabit waters with light levels spanning up to six orders of magnitude. Deep-living krill ascended in synchrony with the rest of the population in the afternoon, but individuals consistently reappeared in near-bottom waters already? 1 h after the ascent. Thereafter, the krill appeared to undertake asynchronous migrations, with some krill always being present in near-bottom waters even though the entire population appeared to undertake DVM. The Author 2013. Published by Oxford University Press. All rights reserved.

  7. Vertical distribution and diel vertical migration of krill beneath snow-covered ice and in ice-free waters

    KAUST Repository

    Vestheim, Hege

    2013-11-11

    A bottom mounted upward looking Simrad EK60 120-kHz echo sounder was used to study scattering layers (SLs) and individuals of the krill Meganyctiphanes norvegica. The mooring was situated at 150-m depth in the Oslofjord, connected with an onshore cable for power and transmission of digitized data. Records spanned 5 months from late autumn to spring. A current meter and CTD was associated with the acoustic mooring and a shore-based webcam monitored ice conditions in the fjord. The continuous measurements were supplemented with intermittent krill sampling campaigns and their physical and biological environment.The krill carried out diel vertical migration (DVM) throughout the winter, regardless of the distribution of potential prey. The fjord froze over in mid-winter and the daytime distribution of a mid-water SL of krill immediately became shallower associated with snow fall after freezing, likely related to reduction of light intensities. Still, a fraction of the population always descended all the way to the bottom, so that the krill population by day seemed to inhabit waters with light levels spanning up to six orders of magnitude. Deep-living krill ascended in synchrony with the rest of the population in the afternoon, but individuals consistently reappeared in near-bottom waters already? 1 h after the ascent. Thereafter, the krill appeared to undertake asynchronous migrations, with some krill always being present in near-bottom waters even though the entire population appeared to undertake DVM. The Author 2013. Published by Oxford University Press. All rights reserved.

  8. Heterogeneous primary nucleation of ice in water and aqueous solutions

    NARCIS (Netherlands)

    Thijssen, H.A.C.; Vorstman, M.A.G.; Roels, J.A.

    1968-01-01

    The effect of the volume of the liquid sample, the degree of turbulence in the liquid, and the rate of cooling upon the probability of nucleation has been studied for water and aqueous solutions. Nucleation rates were measured for droplets nearly instantaneously cooled to a predetermined

  9. Kinetic Monte Carlo simulations of water ice porosity: extrapolations of deposition parameters from the laboratory to interstellar space

    Science.gov (United States)

    Clements, Aspen R.; Berk, Brandon; Cooke, Ilsa R.; Garrod, Robin T.

    2018-02-01

    Using an off-lattice kinetic Monte Carlo model we reproduce experimental laboratory trends in the density of amorphous solid water (ASW) for varied deposition angle, rate and surface temperature. Extrapolation of the model to conditions appropriate to protoplanetary disks and interstellar dark clouds indicate that these ices may be less porous than laboratory ices.

  10. ERS-1 SAR monitoring of ice growth on shallow lakes to determine water depth and availability in north west Alaska

    Science.gov (United States)

    Jeffries, Martin; Morris, Kim; Liston, Glen

    1996-01-01

    Images taken by the ERS-1 synthetic aperture radar (SAR) were used to identify and to differentiate between the lakes that freeze completely to the bottom and those that do not, on the North Slope, in northwestern Alaska. The ice thickness at the time each lake froze completely is determined with numerical ice growth model that gives a maximum simulated thickness of 2.2 m. A method combining the ERS-1 SAR images and numerical ice growth model was used to determine the ice growth and the water availability in these regions.

  11. Cascading water underneath Wilkes Land, East Antarctic ice sheet, observed using altimetry and digital elevation models

    Science.gov (United States)

    Flament, T.; Berthier, E.; Rémy, F.

    2014-04-01

    We describe a major subglacial lake drainage close to the ice divide in Wilkes Land, East Antarctica, and the subsequent cascading of water underneath the ice sheet toward the coast. To analyse the event, we combined altimetry data from several sources and subglacial topography. We estimated the total volume of water that drained from Lake CookE2 by differencing digital elevation models (DEM) derived from ASTER and SPOT5 stereo imagery acquired in January 2006 and February 2012. At 5.2 ± 1.5 km3, this is the largest single subglacial drainage event reported so far in Antarctica. Elevation differences between ICESat laser altimetry spanning 2003-2009 and the SPOT5 DEM indicate that the discharge started in November 2006 and lasted approximately 2 years. A 13 m uplift of the surface, corresponding to a refilling of about 0.6 ± 0.3 km3, was observed between the end of the discharge in October 2008 and February 2012. Using the 35-day temporal resolution of Envisat radar altimetry, we monitored the subsequent filling and drainage of connected subglacial lakes located downstream of CookE2. The total volume of water traveling within the theoretical 500-km-long flow paths computed with the BEDMAP2 data set is similar to the volume that drained from Lake CookE2, and our observations suggest that most of the water released from Lake CookE2 did not reach the coast but remained trapped underneath the ice sheet. Our study illustrates how combining multiple remote sensing techniques allows monitoring of the timing and magnitude of subglacial water flow beneath the East Antarctic ice sheet.

  12. The minimal ice water caloric test compared with established vestibular caloric test procedures.

    Science.gov (United States)

    Schmäl, Frank; Lübben, Björn; Weiberg, Kerstin; Stoll, Wolfgang

    2005-01-01

    Caloric testing of the vestibular labyrinth is usually performed by classical caloric test procedures (CCTP) using water warmed to 30 degrees C and 44 degrees C. Ice water irrigation (4 degrees C) is usually not performed, although it might be useful as a bedside test. To verify the validity of the Minimal Ice Water Caloric Test (MIWCT), comparative video-oculographic investigations were performed in 22 healthy subjects using ice water (0.5 ml, 1.0 ml, 2 ml), CCTP, and cold air (27 degrees C). Frequency, amplitude, slow phase velocity (SPV), the onset, and the duration of nystagmus were documented. After addition of three ice cubes, the temperature of conventional tap water (16 degrees C) fell within 13 min to 4 degrees C. In pessimum position the subjects demonstrated no nystagmus response. Compared to CCTP, MIWCT was associated with a significantly later onset of nystagmus and a significant prolongation of the nystagmus reaction. In contrast to air stimulation (27 degrees C), a significant Spearman's correlation was noted between MIWCT (1 and 2 ml) and established CCTP in respect of essential nystagmus parameters (frequency, amplitude and SPV). Furthermore, MIWCT (0.5 and 1 ml) showed a higher sensitivity and specificity with regard to the detection of canal paresis based on Jongkees' formula compared to stimulation with air 27 degrees C. Thus, MIWCT appears to be a suitable procedure for bedside investigation of vestibular function outside the vestibular laboratory, e.g. in a hospital ward, where bedridden patients with vertigo occasionally require vestibular testing.

  13. New measurements on water ice photodesorption and product formation under ultraviolet irradiation

    Science.gov (United States)

    Cruz-Diaz, Gustavo A.; Martín-Doménech, Rafael; Moreno, Elena; Muñoz Caro, Guillermo M.; Chen, Yu-Jung

    2018-03-01

    The photodesorption of icy grain mantles has been claimed to be responsible for the abundance of gas-phase molecules towards cold regions. Being water a ubiquitous molecule, it is crucial to understand its role in photochemistry and its behaviour under an ultraviolet field. We report new measurements on the ultraviolet (UV) photodesorption of water ice and its H2, OH, and O2 photoproducts using a calibrated quadrupole mass spectrometer. Solid water was deposited under ultra-high-vacuum conditions and then UV-irradiated at various temperatures starting from 8 K with a microwave discharged hydrogen lamp. Deuterated water was used for confirmation of the results. We found a photodesorption yield of 1.3 × 10-3 molecules per incident photon for water and 0.7 × 10-3 molecules per incident photon for deuterated water at the lowest irradiation temperature, 8 K. The photodesorption yield per absorbed photon is given and comparison with astrophysical scenarios, where water ice photodesorption could account for the presence of gas-phase water towards cold regions in the absence of a thermal desorption process, is addressed.

  14. Computational studies of atmospherically-relevant chemical reactions in water clusters and on liquid water and ice surfaces.

    Science.gov (United States)

    Gerber, R Benny; Varner, Mychel E; Hammerich, Audrey D; Riikonen, Sampsa; Murdachaew, Garold; Shemesh, Dorit; Finlayson-Pitts, Barbara J

    2015-02-17

    CONSPECTUS: Reactions on water and ice surfaces and in other aqueous media are ubiquitous in the atmosphere, but the microscopic mechanisms of most of these processes are as yet unknown. This Account examines recent progress in atomistic simulations of such reactions and the insights provided into mechanisms and interpretation of experiments. Illustrative examples are discussed. The main computational approaches employed are classical trajectory simulations using interaction potentials derived from quantum chemical methods. This comprises both ab initio molecular dynamics (AIMD) and semiempirical molecular dynamics (SEMD), the latter referring to semiempirical quantum chemical methods. Presented examples are as follows: (i) Reaction of the (NO(+))(NO3(-)) ion pair with a water cluster to produce the atmospherically important HONO and HNO3. The simulations show that a cluster with four water molecules describes the reaction. This provides a hydrogen-bonding network supporting the transition state. The reaction is triggered by thermal structural fluctuations, and ultrafast changes in atomic partial charges play a key role. This is an example where a reaction in a small cluster can provide a model for a corresponding bulk process. The results support the proposed mechanism for production of HONO by hydrolysis of NO2 (N2O4). (ii) The reactions of gaseous HCl with N2O4 and N2O5 on liquid water surfaces. Ionization of HCl at the water/air interface is followed by nucleophilic attack of Cl(-) on N2O4 or N2O5. Both reactions proceed by an SN2 mechanism. The products are ClNO and ClNO2, precursors of atmospheric atomic chlorine. Because this mechanism cannot result from a cluster too small for HCl ionization, an extended water film model was simulated. The results explain ClNO formation experiments. Predicted ClNO2 formation is less efficient. (iii) Ionization of acids at ice surfaces. No ionization is found on ideal crystalline surfaces, but the process is efficient on

  15. Metal-ion catalyzed polymerization in the eutectic phase in water-ice

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain; Szostak, Jack W.

    2008-01-01

    The emergence of an RNA world requires among other processes the non-enzymatic, template-directed replication of genetic polymers such as RNA or related nucleic acids, possibly catalyzed by metal ions. The absence of uridilate derivative polymerization on adenine containing templates has been...... the main issue preventing an efficient template-directed RNA polymerization. We report here the investigation of template-directed RNA polymerization in the eutectic phase in water-ice. In particular, it was found that activated Uridilate monomers in the presence of metal-ion catalysts could efficiently......-pairing opportunities. These results suggest that a template-directed RNA polymerization catalyzed by metal-ions could be carried out under eutectic phase in water-ice conditions....

  16. Plugging of drinking water flow into horizontal high diameter pipeline with artificial ice plug

    International Nuclear Information System (INIS)

    Gyongyosi, T.; Valeca, S.; Panaitescu, V. N.; Prisecaru, I.

    2013-01-01

    Local isolation of a pipeline section, placed horizontally into a loop of drinking water supply network, can be made with an ice plug resulting after controlled process inside of pipeline without stopping the consumer supply. The technique is applying in order to perform repairs or items replacement, without closing the drinking water supply network at the same time decreasing the fluid loss resulted after discharge of the affected loop. In facts, the technique is simple one and assumes to apply a special device sized for each case using a freezing liquid agent injected continuously. The paper contains a constructive description of the experimental technological facilities and of the experimental model for ice plugging device used. The test, the first results get and some conclusion are following. The paper is dedicated to the specialists working in the research and technological engineering. (authors)

  17. Water on Mars: Inventory, distribution, and possible sources of polar ice

    Science.gov (United States)

    Clifford, S. M.

    1992-01-01

    Theoretical considerations and various lines of morphologic evidence suggest that, in addition to the normal seasonal and climatic exchange of H2O that occurs between the Martian polar caps, atmosphere, and mid to high latitude regolith, large volumes of water have been introduced into the planet's long term hydrologic cycle by the sublimation of equatorial ground ice, impacts, catastrophic flooding, and volcanism. Under the climatic conditions that are thought to have prevailed on Mars throughout the past 3 to 4 b.y., much of this water is expected to have been cold trapped at the poles. The amount of polar ice contributed by each of the planet's potential crustal sources is discussed and estimated. The final analysis suggests that only 5 to 15 pct. of this potential inventory is now in residence at the poles.

  18. Production of sustainable methane from renewable energy and captured carbon dioxide with the use of Solid Oxide Electrolyzer: A thermodynamic assessment

    International Nuclear Information System (INIS)

    Stempien, Jan Pawel; Ni, Meng; Sun, Qiang; Chan, Siew Hwa

    2015-01-01

    A possible pathway for renewable and sustainable methane production from captured carbon dioxide, water (or seawater) and renewable electricity is proposed and analysed. The proposed system includes Solid Oxide Electrolyzer Cell combined with ex-situ methane synthesis reactor comprising Sabatier, Methanation and Water-Gas Shift reactions. A well validated electrochemical model is used to describe the behaviour of the electrolyzer for steam/carbon dioxide co-electrolysis. The methane synthesis reactor is modelled by a set of equations based on thermodynamic equilibrium reaction constants. Effects of current density, temperature, pressure and initial steam to carbon dioxide ratio on system performance are analysed and their effects are discussed. It is found that a simple, single-pass system without heat recuperation could achieve a maximum overall energy efficiency of 60.87% (based on lower heating value), a maximum electrical energy efficiency of 81.08% (based on lower heating value), and a maximum amount of methane production of ∼1.52 Nm 3  h −1  m −2 of electrolyzer. It is also found that conversion of ∼100% captured carbon dioxide is possible in the proposed system. - Highlights: • Analysis of Solid Oxide Electrolyzer combined with methane synthesis process. • Efficiency of converting water and carbon dioxide into synthetic, renewable methane above 81%. • Effects of process temperature, pressure, gas flux and compositions were analysed. • Methane production of ∼1.52 [Nm 3 h −1 m −2 of electrolyzer]. • Conversion of ∼100% of captured CO 2 is possible

  19. Water ice as a matrix for film production by matrix-assisted pulsed laser evaporation (MAPLE)

    International Nuclear Information System (INIS)

    Rodrigo, K; Schou, J; Toftmann, B; Pedrys, R

    2007-01-01

    We have studied water ice as a matrix for the production of PEG (polyethylene glycol) films by MAPLE at 355 nm. The deposition rate is small compared with other matrices typically used in MAPLE, but the deposition of photofragments from the matrix can be avoided. At temperatures above -50deg. C of the target holder the deposition rate increases strongly, but the evaporation pressure in the MAPLE chamber also increases drastically

  20. Water ice as a matrix for film production by matrix assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Rodrigo, Katarzyna Agnieszka; Schou, Jørgen; Christensen, Bo Toftmann

    2007-01-01

    We have studied water ice as a matrix for the production of PEG (polyethylene glycol) films by MAPLE at 355 nm. The deposition rate is small compared with other matrices typically used in MAPLE, but the deposition of photofragments from the matrix can be avoided. At temperatures above -50 degrees C...... of the target holder the deposition rate increases strongly, but the evaporation pressure in the MAPLE chamber also increases drastically....

  1. Atypical water lattices and their possible relevance to the amorphous ices: A density functional study

    Energy Technology Data Exchange (ETDEWEB)

    Anick, David J. [Laboratory for Water and Surface Studies, Department of Chemistry, Pearson Lab, Tufts University, Medford, MA 02155 (United States)

    2013-04-15

    Of the fifteen known crystalline forms of ice, eleven consist of a single topologically connected hydrogen bond network with four H-bonds at every O. The other four, Ices VI–VIII and XV, consist of two topologically connected networks, each with four H-bonds at every O. The networks interpenetrate but do not share H-bonds. This article presents two new periodic water lattice families whose topological connectivity is “atypical”: they consist of many two-dimensional layers that share no H-bonds. Layers are held together only by dispersion forces. Within each layer there are still four H-bonds at each O. Called “Hexagonal Bilayer Water” (HBW) and “Pleated Sheet Water” (PSW), they have computed densities of about 1.1 g/mL and 1.3 g/mL respectively, and nearest neighbor O-coordination is 4.5 to 5.5 and 6 to 8 respectively. Using density functional theory (BLYP-D/TZVP), various proton ordered forms of HBW and PSW are optimized and categorized. There are simple pathways connecting Ice-Ih to HBW and HBW to PSW. Their computed properties suggest similarities to the high density and very high density amorphous ices (HDA and VHDA) respectively. It is unknown whether HDA, VHDA, and Low Density Amorphous Ice (LDA) are fully disordered glasses down to the molecular level, or whether there is some short-range local order. Based on estimated radial distribution functions (RDFs), one proton ordered form of HBW matches HDA best. The idea is explored that HDA could contain islands with this underlying structure, and likewise, that VHDA could contain regions of PSW. A “microlattice model version 1” (MLM1) is presented as a device to compare key experimental data on the amorphous ices with these atypical structures and with a microlattice form of Ice-XI for LDA. Resemblances are found with the amorphs’ RDFs, densities, Raman spectra, and transition behaviors. There is not enough information in the static models to assign either a microlattice structure or a partial

  2. Atypical water lattices and their possible relevance to the amorphous ices: A density functional study

    Directory of Open Access Journals (Sweden)

    David J. Anick

    2013-04-01

    Full Text Available Of the fifteen known crystalline forms of ice, eleven consist of a single topologically connected hydrogen bond network with four H-bonds at every O. The other four, Ices VI–VIII and XV, consist of two topologically connected networks, each with four H-bonds at every O. The networks interpenetrate but do not share H-bonds. This article presents two new periodic water lattice families whose topological connectivity is “atypical”: they consist of many two-dimensional layers that share no H-bonds. Layers are held together only by dispersion forces. Within each layer there are still four H-bonds at each O. Called “Hexagonal Bilayer Water” (HBW and “Pleated Sheet Water” (PSW, they have computed densities of about 1.1 g/mL and 1.3 g/mL respectively, and nearest neighbor O-coordination is 4.5 to 5.5 and 6 to 8 respectively. Using density functional theory (BLYP-D/TZVP, various proton ordered forms of HBW and PSW are optimized and categorized. There are simple pathways connecting Ice-Ih to HBW and HBW to PSW. Their computed properties suggest similarities to the high density and very high density amorphous ices (HDA and VHDA respectively. It is unknown whether HDA, VHDA, and Low Density Amorphous Ice (LDA are fully disordered glasses down to the molecular level, or whether there is some short-range local order. Based on estimated radial distribution functions (RDFs, one proton ordered form of HBW matches HDA best. The idea is explored that HDA could contain islands with this underlying structure, and likewise, that VHDA could contain regions of PSW. A “microlattice model version 1” (MLM1 is presented as a device to compare key experimental data on the amorphous ices with these atypical structures and with a microlattice form of Ice-XI for LDA. Resemblances are found with the amorphs’ RDFs, densities, Raman spectra, and transition behaviors. There is not enough information in the static models to assign either a microlattice structure

  3. Atypical water lattices and their possible relevance to the amorphous ices: A density functional study

    International Nuclear Information System (INIS)

    Anick, David J.

    2013-01-01

    Of the fifteen known crystalline forms of ice, eleven consist of a single topologically connected hydrogen bond network with four H-bonds at every O. The other four, Ices VI–VIII and XV, consist of two topologically connected networks, each with four H-bonds at every O. The networks interpenetrate but do not share H-bonds. This article presents two new periodic water lattice families whose topological connectivity is “atypical”: they consist of many two-dimensional layers that share no H-bonds. Layers are held together only by dispersion forces. Within each layer there are still four H-bonds at each O. Called “Hexagonal Bilayer Water” (HBW) and “Pleated Sheet Water” (PSW), they have computed densities of about 1.1 g/mL and 1.3 g/mL respectively, and nearest neighbor O-coordination is 4.5 to 5.5 and 6 to 8 respectively. Using density functional theory (BLYP-D/TZVP), various proton ordered forms of HBW and PSW are optimized and categorized. There are simple pathways connecting Ice-Ih to HBW and HBW to PSW. Their computed properties suggest similarities to the high density and very high density amorphous ices (HDA and VHDA) respectively. It is unknown whether HDA, VHDA, and Low Density Amorphous Ice (LDA) are fully disordered glasses down to the molecular level, or whether there is some short-range local order. Based on estimated radial distribution functions (RDFs), one proton ordered form of HBW matches HDA best. The idea is explored that HDA could contain islands with this underlying structure, and likewise, that VHDA could contain regions of PSW. A “microlattice model version 1” (MLM1) is presented as a device to compare key experimental data on the amorphous ices with these atypical structures and with a microlattice form of Ice-XI for LDA. Resemblances are found with the amorphs’ RDFs, densities, Raman spectra, and transition behaviors. There is not enough information in the static models to assign either a microlattice structure or a partial

  4. Rate of Homogenous Nucleation of Ice in Supercooled Water.

    Science.gov (United States)

    Atkinson, James D; Murray, Benjamin J; O'Sullivan, Daniel

    2016-08-25

    The homogeneous freezing of water is of fundamental importance to a number of fields, including that of cloud formation. However, there is considerable scatter in homogeneous nucleation rate coefficients reported in the literature. Using a cold stage droplet system designed to minimize uncertainties in temperature measurements, we examined the freezing of over 1500 pure water droplets with diameters between 4 and 24 μm. Under the assumption that nucleation occurs within the bulk of the droplet, nucleation rate coefficients fall within the spread of literature data and are in good agreement with a subset of more recent measurements. To quantify the relative importance of surface and volume nucleation in our experiments, where droplets are supported by a hydrophobic surface and surrounded by oil, comparison of droplets with different surface area to volume ratios was performed. From our experiments it is shown that in droplets larger than 6 μm diameter (between 234.6 and 236.5 K), nucleation in the interior is more important than nucleation at the surface. At smaller sizes we cannot rule out a significant contribution of surface nucleation, and in order to further constrain surface nucleation, experiments with smaller droplets are necessary. Nevertheless, in our experiments, it is dominantly volume nucleation controlling the observed nucleation rate.

  5. Heterogeneous Ice Nucleation by Soufriere Hills Volcanic Ash Immersed in Water Droplets.

    Directory of Open Access Journals (Sweden)

    T P Mangan

    Full Text Available Fine particles of ash emitted during volcanic eruptions may sporadically influence cloud properties on a regional or global scale as well as influencing the dynamics of volcanic clouds and the subsequent dispersion of volcanic aerosol and gases. It has been shown that volcanic ash can trigger ice nucleation, but ash from relatively few volcanoes has been studied for its ice nucleating ability. In this study we quantify the efficiency with which ash from the Soufriere Hills volcano on Montserrat nucleates ice when immersed in supercooled water droplets. Using an ash sample from the 11th February 2010 eruption, we report ice nucleating efficiencies from 246 to 265 K. This wide range of temperatures was achieved using two separate droplet freezing instruments, one employing nanolitre droplets, the other using microlitre droplets. Soufriere Hills volcanic ash was significantly more efficient than all other ash samples that have been previously examined. At present the reasons for these differences are not understood, but may be related to mineralogy, amorphous content and surface chemistry.

  6. Heterogeneous Ice Nucleation by Soufriere Hills Volcanic Ash Immersed in Water Droplets.

    Science.gov (United States)

    Mangan, T P; Atkinson, J D; Neuberg, J W; O'Sullivan, D; Wilson, T W; Whale, T F; Neve, L; Umo, N S; Malkin, T L; Murray, B J

    2017-01-01

    Fine particles of ash emitted during volcanic eruptions may sporadically influence cloud properties on a regional or global scale as well as influencing the dynamics of volcanic clouds and the subsequent dispersion of volcanic aerosol and gases. It has been shown that volcanic ash can trigger ice nucleation, but ash from relatively few volcanoes has been studied for its ice nucleating ability. In this study we quantify the efficiency with which ash from the Soufriere Hills volcano on Montserrat nucleates ice when immersed in supercooled water droplets. Using an ash sample from the 11th February 2010 eruption, we report ice nucleating efficiencies from 246 to 265 K. This wide range of temperatures was achieved using two separate droplet freezing instruments, one employing nanolitre droplets, the other using microlitre droplets. Soufriere Hills volcanic ash was significantly more efficient than all other ash samples that have been previously examined. At present the reasons for these differences are not understood, but may be related to mineralogy, amorphous content and surface chemistry.

  7. Gradient Meshed and Toughened SOEC (Solid Oxide Electrolyzer Cell) Composite Seal with Self-Healing Capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Kathy Lu; W. T. Reynolds, Jr.

    2010-06-08

    High-temperature electrolysis of water steam is a promising approach for hydrogen production. The potential is even more promising when abundant heat source from nuclear power reactors can be efficiently utilized. Hydrogen production through the above approach also allows for low electric consumption. Overall energy conversion efficiencies for high temperature electrolysis are in the 45-50% range compared to ~30% for the conventional electrolysis. Under such motivation, this research is focused on increasing the operation time and high temperature stability of solid oxide electrolyzer cells (SOEC) for splitting water into hydrogen. Specifically, our focus is to improve the SOEC seal thermal stability and performances by alleviating thermal stress and seal cracking issues.

  8. AN INVESTIGATION INTO THE EFFECT OF PHOTOVOLTAIC MODULE ELECTRIC PROPERTIES ON MAXIMUM POWER POINT TRAJECTORY WITH THE AIM OF ITS ALIGNMENT WITH ELECTROLYZER U-I CHARACTERISTIC

    Directory of Open Access Journals (Sweden)

    Mihajlo Firak

    2010-01-01

    Full Text Available In order to combine a photovoltaic module and an electrolyzer to produce hydrogen from water, an intermediate DC/DC converter can be used to adapt output power features of the module to input power features of the electrolyzer. This can also be done without using electronics, which results in saving as much as 700 USD/kW, as previous investigation has shown. A more sophisticated investigation should be carried out with the aim of improving high system efficiency, resulting in matching the photovoltaic module maximum power point trajectory (the maximum power point path in the U-I plane as a result of solar irradiance change to the operating characteristic of the electrolyzer. This paper presents an analysis of the influences of photovoltaic module electric properties, such as series and parallel resistance and non-ideality factor, on the maximum power point trajectory at different levels of solar irradiance. The possibility of various inclinations (right - vertical - left in relation to an arbitrary chosen operating characteristic of the electrolyzer is also demonstrated. Simulated results are obtained by using Matlab/Simulink simulations of the well known one-diode model. Simulations have been confirmed with experiments on a real photovoltaic module where solar irradiance, solar cell temperature, electric current, and voltage in the circuit with variable ohmic resistance have been measured.

  9. Up-going Red Water in the Ice at the Bottom of the World: Picture Taking Boxes and Listening Boxes Tell Us How and Why

    Science.gov (United States)

    Carr, C. G.; Pettit, E. C.

    2017-12-01

    Blood Falls is a place where red water comes out from under ice to the top of the ice and makes a strange red water fall. This ice is part of the big ice at the bottom of the world. The red water only comes out at some times and not every year, but it always comes out at the same place. The red water is important because it has tiny tiny not-animal life that tells us how life could be on other worlds. Knowing about the ice and red water is important because this ice is cold, colder than other ice in other places, and we want to know how water can get through. We didn't know why the red water comes up from under the ice when it does or how. We wanted to understand how the ice breaks and we watched the ice by taking pictures all year to see when the red water comes out. We found out that in the cold part of one year, the red water came out even though the air was not warm enough for water to be water! We think the red water comes out because the red water is blocked under the heavy ice and gets pushed tight. In the cold part of the year, cracks break down from the air into the ice and other cracks break up from under the ice because the red water is so pushed. The cracks from the top and bottom of the ice join, and the red water comes out. We used listening boxes that can feel how the ground moves to understand that the ice is breaking at the bottom and we can see that it breaks at the top of the ice. The red water can stay water and not ice inside the big ice because the red water has tiny pieces of the same stuff that can turn ice into water on the roads. If the ice breaks in the cold time, no water can get in from the top of the ice, so the red water under the ice stays clean from the air water. If the ice breaks in the warm time of year, water could get in from the top of the ice and make the red water under the ice not clean from the air. Since we saw in our pictures that the red water came out in the cold time of year, this means the red water could stay clean

  10. STICKING OF MOLECULES ON NONPOROUS AMORPHOUS WATER ICE

    Energy Technology Data Exchange (ETDEWEB)

    He, Jiao; Vidali, Gianfranco [Physics Department, Syracuse University, Syracuse, NY 13244 (United States); Acharyya, Kinsuk, E-mail: gvidali@syr.edu [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States)

    2016-05-20

    Accurate modeling of physical and chemical processes in the interstellar medium (ISM) requires detailed knowledge of how atoms and molecules adsorb on dust grains. However, the sticking coefficient, a number between 0 and 1 that measures the first step in the interaction of a particle with a surface, is usually assumed in simulations of ISM environments to be either 0.5 or 1. Here we report on the determination of the sticking coefficient of H{sub 2}, D{sub 2}, N{sub 2}, O{sub 2}, CO, CH{sub 4}, and CO{sub 2} on nonporous amorphous solid water. The sticking coefficient was measured over a wide range of surface temperatures using a highly collimated molecular beam. We showed that the standard way of measuring the sticking coefficient—the King–Wells method—leads to the underestimation of trapping events in which there is incomplete energy accommodation of the molecule on the surface. Surface scattering experiments with the use of a pulsed molecular beam are used instead to measure the sticking coefficient. Based on the values of the measured sticking coefficient, we suggest a useful general formula of the sticking coefficient as a function of grain temperature and molecule-surface binding energy. We use this formula in a simulation of ISM gas–grain chemistry to find the effect of sticking on the abundance of key molecules both on grains and in the gas phase.

  11. Reduced cerebral perfusion on sudden immersion in ice water: a possible cause of drowning

    DEFF Research Database (Denmark)

    Mantoni, Teit; Belhage, Bo; Pedersen, Lars M

    2007-01-01

    INTRODUCTION: Near-drowning incidents and drowning deaths after accidental immersion in open waters have been linked to cold shock response. It consists of inspiratory gasps, hyperventilation, tachycardia, and hypertension in the first 2-3 min of cold-water immersion. This study explored the imme......INTRODUCTION: Near-drowning incidents and drowning deaths after accidental immersion in open waters have been linked to cold shock response. It consists of inspiratory gasps, hyperventilation, tachycardia, and hypertension in the first 2-3 min of cold-water immersion. This study explored...... cerebral artery (MCA) was measured together with ventilatory parameters and heart rate before, during, and after immersion. RESULTS: Within seconds after immersion in ice water, heart rate increased from 74 +/- 16 to 107 +/- 18 bpm (mean +/- SD; p elevation...

  12. Earth's field NMR detection of oil under arctic ice-water suppression

    Science.gov (United States)

    Conradi, Mark S.; Altobelli, Stephen A.; Sowko, Nicholas J.; Conradi, Susan H.; Fukushima, Eiichi

    2018-03-01

    Earth's field NMR has been developed to detect oil trapped under or in Arctic sea-ice. A large challenge, addressed here, is the suppression of the water signal that dominates the oil signal. Selective suppression of water is based on relaxation time T1 because of the negligible chemical shifts in the weak earth's magnetic field, making all proton signals overlap spectroscopically. The first approach is inversion-null recovery, modified for use with pre-polarization. The requirements for efficient inversion over a wide range of B1 and subsequent adiabatic reorientation of the magnetization to align with the static field are stressed. The second method acquires FIDs at two durations of pre-polarization and cancels the water component of the signal after the data are acquired. While less elegant, this technique imposes no stringent requirements. Similar water suppression is found in simulations for the two methods. Oil detection in the presence of water is demonstrated experimentally with both techniques.

  13. Structural Models of Water and Ice Regarding the Energy of Hydrogen Bonding

    OpenAIRE

    Ignat Ignatov; Oleg Mosin

    2015-01-01

    In this review it is reported about the research on the structure of water and ice and intermolecular water cyclic associates (clusters) with general formula (Н2О)n and their charged ionic clusters [(Н2О)n]+ and [(Н2О)n]- by means of computer modelling and spectroscopy methods as 1Н-NMR, IR-spectroscopy, DNES, EXAFS-spectroscopy, X-Ray and neurons diffraction. The computer calculation of polyhedral nanoclusters (Н2О)n, where n = 3–20 are carried out. Based on this data the main structural mat...

  14. Voluntary respiratory control and cerebral blood flow velocity upon ice-water immersion

    DEFF Research Database (Denmark)

    Mantoni, Teit; Rasmussen, Jakob Højlund; Belhage, Bo

    2008-01-01

    INTRODUCTION: In non-habituated subjects, cold-shock response to cold-water immersion causes rapid reduction in cerebral blood flow velocity (approximately 50%) due to hyperventilation, increasing risk of syncope, aspiration, and drowning. Adaptation to the response is possible, but requires...... velocity (CBFV) was measured together with ventilatory parameters and heart rate before, during, and after immersion. RESULTS: Within seconds after immersion in ice-water, heart rate increased significantly from 95 +/- 8 to 126 +/- 7 bpm (mean +/- SEM). Immersion was associated with an elevation...

  15. Experimental study of natural convection adjacent to an isothermal vertical ice cylinder in cold pure water

    International Nuclear Information System (INIS)

    Riu, Kap Jong; Yea, Yong Taeg; Park, Sang Hee

    1991-01-01

    A natural convection adjacent to an isothermal vertical ice cylinder is studied experimentally in cold pure water. The experiments are carried out as changing the temperature of the ambient water and then the flow and heat transfer characteristics is visualized and observed. It is shown that flow patterns are steady state upflow, unsteady state flow, steady state dual flow, and steady state downflow. There is also obtained a heat transfer coefficient and mean Nusselt number at various ambient temperature. These results are in good agreement with the theoretical ones. (Author)

  16. A water activity based model of heterogeneous ice nucleation kinetics for freezing of water and aqueous solution droplets.

    Science.gov (United States)

    Knopf, Daniel A; Alpert, Peter A

    2013-01-01

    Immersion freezing of water and aqueous solutions by particles acting as ice nuclei (IN) is a common process of heterogeneous ice nucleation which occurs in many environments, especially in the atmosphere where it results in the glaciation of clouds. Here we experimentally show, using a variety of IN types suspended in various aqueous solutions, that immersion freezing temperatures and kinetics can be described solely by temperature, T, and solution water activity, a(w), which is the ratio of the vapour pressure of the solution and the saturation water vapour pressure under the same conditions and, in equilibrium, equivalent to relative humidity (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, J(het), to be uniquely expressed by T and a(w), a result we term the a(w) based immersion freezing model (ABIFM). This method is independent of the nature of the solute and accounts for several varying parameters, including cooling rate and IN surface area, while providing a holistic description of immersion freezing and allowing prediction of freezing temperatures, J(het), frozen fractions, ice particle production rates and numbers. Our findings are based on experimental freezing data collected for various IN surface areas, A, and cooling rates, r, of droplets variously containing marine biogenic material, two soil humic acids, four mineral dusts, and one organic monolayer acting as IN. For all investigated IN types we demonstrate that droplet freezing temperatures increase as A increases. Similarly, droplet freezing temperatures increase as the cooling rate decreases. The log10(J(het)) values for the various IN types derived exclusively by Tand a(w), provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Lastly, we demonstrate that ABIFM can

  17. A modified QWASI model for fate and transport modeling of mercury between the water-ice-sediment in Lake Ulansuhai.

    Science.gov (United States)

    Liu, Yu; Li, Changyou; Anderson, Bruce; Zhang, Sheng; Shi, Xiaohong; Zhao, Shengnan

    2017-06-01

    Mercury contamination from industrial and agricultural drainage into lakes and rivers is a growing concern in Northern China. Lake Ulansuhai, located in Hetao irrigation district in Inner Mongolia, is the only sink for the all industrial and agricultural drainage and sole outlet for this district to the Yellow River, which is one of the main source of drinking water for the numerous cities and towns downstream. Because Ulansuahi is ice-covered during winter, the QWASI model was modified by adding an ice equation to get a more accurate understanding of the fate and transport of mercury within the lake. Both laboratory and field tests were carried out during the ice growth period. The aquivalence and mass balance approaches were used to develop the modified QWASI + ice model. The margins of error between the modelled and the measured average concentrations of Hg in ice, water, and sediment were 30%, 26.2%, and 19.8% respectively. These results suggest that the new QWASI + ice model could be used to more accurately represent the fate and transport of mercury in the seasonally ice-covered lakes, during the ice growth period. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Comparison of carbon monoxide levels during heating of ice and water to boiling point with a camping stove.

    Science.gov (United States)

    Leigh-Smith, Simon; Watt, Ian; McFadyen, Angus; Grant, Stan

    2004-01-01

    To determine whether using a camping stove to bring a pan of ice to boiling point produces higher carbon monoxide (CO) concentration than would bringing a pan of water to boiling point. The hypothesis was that ice would cause greater CO concentration because of its greater flame-cooling effect and, consequently, more incomplete combustion. This was a randomized, prospective observational study. After an initial pilot study, CO concentration was monitored during 10 trials for each of ice and water. A partially ventilated 200-L cardboard box model was developed and then used inside a chamber at -6 degrees C. Ice temperature and volume, water temperature and volume, pan size, and flame characteristics were all standardized. Temperature of the heated medium was monitored to determine time to boiling point. Carbon monoxide concentration was monitored every 30 seconds for the first 3 minutes, then every minute until the end of each 10-minute trial. There was no significant difference (P > .05) in CO production levels between ice and water. Each achieved a similar mean plateau level of approximately 400 ppm CO concentration with a similar rate of rise. However, significantly higher (P = .014) CO concentration occurred at 4 and 5 minutes when the flame underwent a yellow flare; this occurred only on 3 occasions when ice was the medium. There were no significant differences for CO production between bringing a pan of ice or water to boiling point. In a small number of ice trials, the presence of a yellow flame resulted in high CO concentration. Yellow flares might occur more often with ice or snow melting, but this has not been proven.

  19. Optimal Electromagnetic (EM) Geophysical Techniques to Map the Concentration of Subsurface Ice and Adsorbed Water on Mars and the Moon

    Science.gov (United States)

    Stillman, D. E.; Grimm, R. E.

    2013-12-01

    Water ice is ubiquitous in our Solar System and is a probable target for planetary exploration. Mapping the lateral and vertical concentration of subsurface ice from or near the surface could determine the origin of lunar and martian ice and quantify a much-needed resource for human exploration. Determining subsurface ice concentration on Earth is not trivial and has been attempted previously with electrical resistivity tomography (ERT), ground penetrating radar (GPR), airborne EM (AEM), and nuclear magnetic resonance (NMR). These EM geophysical techniques do not actually detect ice, but rather the absence of unfrozen water. This causes a non-unique interpretation of frozen and dry subsurface sediments. This works well in the arctic because most locations are not dry. However, for planetary exploration, liquid water is exceedingly rare and subsurface mapping must discriminate between an ice-rich and a dry subsurface. Luckily, nature has provided a unique electrical signature of ice: its dielectric relaxation. The dielectric relaxation of ice creates a temperature and frequency dependence of the electrical properties and varies the relative dielectric permittivity from ~3.1 at radar frequencies to >100 at low frequencies. On Mars, sediments smaller than silt size can hold enough adsorbed unfrozen water to complicate the measurement. This is because the presence of absorbed water also creates frequency-dependent electrical properties. The dielectric relaxation of adsorbed water and ice can be separated as they have different shapes and frequency ranges as long as a spectrum spanning the two relaxations is measured. The volume concentration of ice and adsorbed water is a function of the strength of their relaxations. Therefore, we suggest that capacitively-coupled dielectric spectroscopy (a.k.a. spectral induced polarization or complex resistivity) can detect the concentration of both ice and adsorbed water in the subsurface. To prove this concept we have collected

  20. Hydrogen by electrolysis of water

    Science.gov (United States)

    1975-01-01

    Hydrogen production by electrolytic decomposition of water is explained. Power efficiency, efficient energy utilization, and costs were emphasized. Four systems were considered: two were based on current electrolyzer technology using present efficiency values for electrical generation by fossil fired and nuclear thermal stations, and two using projected electrolyzer technology with advanced fossil and nuclear plants.

  1. Photochemistry of PAHs in cosmic water ice. The effect of concentration on UV-VIS spectroscopy and ionization efficiency

    Science.gov (United States)

    Cuylle, Steven H.; Allamandola, Louis J.; Linnartz, Harold

    2014-02-01

    Context. Observations and models show that polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the interstellar medium. Like other molecules in dense clouds, PAHs accrete onto interstellar dust grains, where they are embedded in an ice matrix dominated by water. In the laboratory, mixed molecular ices (not containing PAHs) have been extensively studied using Fourier transform infrared absorption spectroscopy. Experiments including PAHs in ices have started, however, the concentrations used are typically much higher than the concentrations expected for interstellar ices. Optical spectroscopy offers a sensitive alternative. Aims: We report an experimental study of the effect PAH concentration has on the electronic spectra and the vacuum UV (VUV) driven processes of PAHs in water-rich ices. The goal is to apply the outcome to cosmic ices. Methods: Optical spectroscopic studies allow us to obtain in-situ and quasi real-time electronic solid state spectra of two prototypical PAHs (pyrene and coronene) embedded in water ice under VUV photoprocessing. The study is carried out on PAH:H2O concentrations in the range of 1:30 000 to pure PAH, covering the temperature range from 12 to 125 K. Results: PAH concentration strongly influences the efficiency of PAH cation formation. At low concentrations, ionization efficiencies are over 60% dropping to about 15% at 1:1000. Increasing the PAH concentration reveals spectral broadening in neutral and cation PAH spectra attributed to PAH clustering inside the ice. At the PAH concentrations expected for interstellar ices, some 10 to 20% may be present as cations. The presence of PAHs in neutral and ion form will add distinctive absorption bands to cosmic ice optical spectra and this may serve as a tool to determine PAH concentrations.

  2. Homogeneous ice nucleation from aqueous inorganic/organic particles representative of biomass burning: water activity, freezing temperatures, nucleation rates.

    Science.gov (United States)

    Knopf, Daniel A; Rigg, Yannick J

    2011-02-10

    Homogeneous ice nucleation plays an important role in the formation of cirrus clouds with subsequent effects on the global radiative budget. Here we report on homogeneous ice nucleation temperatures and corresponding nucleation rate coefficients of aqueous droplets serving as surrogates of biomass burning aerosol. Micrometer-sized (NH(4))(2)SO(4)/levoglucosan droplets with mass ratios of 10:1, 1:1, 1:5, and 1:10 and aqueous multicomponent organic droplets with and without (NH(4))(2)SO(4) under typical tropospheric temperatures and relative humidities are investigated experimentally using a droplet conditioning and ice nucleation apparatus coupled to an optical microscope with image analysis. Homogeneous freezing was determined as a function of temperature and water activity, a(w), which was set at droplet preparation conditions. The ice nucleation data indicate that minor addition of (NH(4))(2)SO(4) to the aqueous organic droplets renders the temperature dependency of water activity negligible in contrast to the case of aqueous organic solution droplets. The mean homogeneous ice nucleation rate coefficient derived from 8 different aqueous droplet compositions with average diameters of ∼60 μm for temperatures as low as 195 K and a(w) of 0.82-1 is 2.18 × 10(6) cm(-3) s(-1). The experimentally derived freezing temperatures and homogeneous ice nucleation rate coefficients are in agreement with predictions of the water activity-based homogeneous ice nucleation theory when taking predictive uncertainties into account. However, the presented ice nucleation data indicate that the water activity-based homogeneous ice nucleation theory overpredicts the freezing temperatures by up to 3 K and corresponding ice nucleation rate coefficients by up to ∼2 orders of magnitude. A shift of 0.01 in a(w), which is well within the uncertainty of typical field and laboratory relative humidity measurements, brings experimental and predicted freezing temperatures and homogeneous ice

  3. Decompression-induced melting of ice IV and the liquid-liquid transition in water

    Science.gov (United States)

    Mishima, Osamu; Stanley, H. Eugene

    1998-03-01

    Although liquid water has been the focus of intensive research for over 100 years, a coherent physical picture that unifies all of the known anomalies of this liquid, is still lacking. Some of these anomalies occur in the supercooled region, and have been rationalized on the grounds of a possible retracing of the liquid-gas spinodal (metastability limit) line into the supercooled liquid region, or alternatively the presence of a line of first-order liquid-liquid phase transitions in this region which ends in a critical point,. But these ideas remain untested experimentally, in part because supercooled water can be probed only above the homogeneous nucleation temperature TH at which water spontaneously crystallizes. Here we report an experimental approach that is not restricted by the barrier imposed by TH, involving measurement of the decompression-induced melting curves of several high-pressure phases of ice in small emulsified droplets. We find that the melting curve for ice IV seems to undergo a discontinuity at precisely the location proposed for the line of liquid-liquid phase transitions. This is consistent with, but does not prove, the coexistence of two different phases of (supercooled) liquid water. From the experimental data we calculate a possible Gibbs potential surface and a corresponding equation of state for water, from the forms of which we estimate the coordinates of the liquid-liquid critical point to be at pressure Pc ~ 0.1GPa and temperature Tc ~ 220K.

  4. Ice-water convection in an inclined rectangular cavity filled with a porous medium

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X. (Dept. of Mechanical Engineering, Ecole Polytechnique de Montreal (Canada)); Kahawita, R. (Dept. of Civil Engineering, Ecole Polytechnique de Montreal (Canada))

    1994-10-01

    This paper reports on the results of a numerical study on the equilibrium state of the convection of water in the presence of ice in an inclined rectangular cavity filled with a porous medium. One side of the cavity is maintained at a temperature higher than the fusion temperature while the opposite side is cooled to a temperature lower than the fusion temperature. The two remaining sides are insulated. Results are analysed in terms of the density inversion parameter, the tilt angle, and the cooling temperature. It appears that the phenomenon of density inversion plays an important role in the equilibrium of an ice-water system when the heating temperature is below 20 . In a vertical cavity, the density inversion causes the formation of two counter-rotating vortices leading to a water volume which is wider at the bottom than at the top. When the cavity is inclined, there exist two branches of solutions which exhibit the bottom heating and the side heating characteristics, respectively (the Benard and side heating branches). Due to the inversion of density, the solution on the Benard branch may fail to converge to a steady state at small tilt angles and exhibits an oscillating behavior. On the side heating branch, a maximum heat transfer rate is obtained at a tilt angle of about 70 but the water volume was found to depend very weakly on the inclination of the cavity. Under the effect of subcooling, the interplay between conduction in the solid phase and convection in the liquid leads to an equilibrium ice-water interface which is most distorted at some intermediate cooling temperature. (orig.)

  5. Volcanic flows versus water- and ice-related outburst deposits in eastern Hellas: A comparison

    Science.gov (United States)

    Voelker, M.; Hauber, E.; Stephan, K.; Jaumann, R.

    2018-06-01

    Hellas Planitia is one of the major topographic sinks on Mars for the deposition of any kind of sediments. We report on our observations of sheet deposits in the eastern part of the basin that are apparently related to the Dao Vallis outflow channel. The deposits have lobate flow fronts and a thickness of a few decameters. Despite their generally smooth surface, some distinctive textures and patterns can be identified, such as longitudinal lineations, distributive channels, and polygons. We compared these deposits to other sheet deposits on Mars and tested three hypotheses of their origin: volcanic flows as well as water- and ice-related mass wastings. Despite some similarities to volcanic sheet flows on Mars, we found several morphological characteristics that are not known for sheet lava flows; for example conically arranged lineations and channel systems very similar to fluvial incisions. We also reject an ice-related formation similar to terrestrial rock-ice avalanches, as there is no sufficient relief energy to explain their extent and location. A water-related origin appears most consistent with our observations, and we favor an emplacement by fluvially-driven mass wasting processes, e.g., debris flows. Assuming a water-related origin, we calculated the amount of water that would be required to deposit such large sedimentary bodies for different flow types. Our calculations show a large range of possible water volumes, from 64 to 2,042 km³, depending on the specific flow mechanism. The close link to Dao Vallis makes these deposits a unique place to study the deposition of outflow channel sediments, as the deposits of other outflow channels on Mars, such as those around Chryse Planitia, are mostly buried by younger sediments and volcanic flows.

  6. GLERL Radiation Transfer Through Freshwater Ice

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Radiation transmittance (ratio of transmitted to incident radiation) through clear ice, refrozen slush ice and brash ice, from ice surface to ice-water interface in...

  7. Reassessment of the Upper Fremont Glacier ice-core chronologies by synchronizing of ice-core-water isotopes to a nearby tree-ring chronology

    Science.gov (United States)

    Chellman, Nathan J.; McConnell, Joseph R.; Arienzo, Monica; Pederson, Gregory T.; Aarons, Sarah; Csank, Adam

    2017-01-01

    The Upper Fremont Glacier (UFG), Wyoming, is one of the few continental glaciers in the contiguous United States known to preserve environmental and climate records spanning recent centuries. A pair of ice cores taken from UFG have been studied extensively to document changes in climate and industrial pollution (most notably, mid-19th century increases in mercury pollution). Fundamental to these studies is the chronology used to map ice-core depth to age. Here, we present a revised chronology for the UFG ice cores based on new measurements and using a novel dating approach of synchronizing continuous water isotope measurements to a nearby tree-ring chronology. While consistent with the few unambiguous age controls underpinning the previous UFG chronologies, the new interpretation suggests a very different time scale for the UFG cores with changes of up to 80 years. Mercury increases previously associated with the mid-19th century Gold Rush now coincide with early-20th century industrial emissions, aligning the UFG record with other North American mercury records from ice and lake sediment cores. Additionally, new UFG records of industrial pollutants parallel changes documented in ice cores from southern Greenland, further validating the new UFG chronologies while documenting the extent of late 19th and early 20th century pollution in remote North America.

  8. COMPUTATIONAL STUDY OF INTERSTELLAR GLYCINE FORMATION OCCURRING AT RADICAL SURFACES OF WATER-ICE DUST PARTICLES

    International Nuclear Information System (INIS)

    Rimola, Albert; Sodupe, Mariona; Ugliengo, Piero

    2012-01-01

    Glycine is the simplest amino acid, and due to the significant astrobiological implications that suppose its detection, the search for it in the interstellar medium (ISM), meteorites, and comets is intensively investigated. In the present work, quantum mechanical calculations based on density functional theory have been used to model the glycine formation on water-ice clusters present in the ISM. The removal of either one H atom or one electron from the water-ice cluster has been considered to simulate the effect of photolytic radiation and of ionizing particles, respectively, which lead to the formation of OH . radical and H 3 O + surface defects. The coupling of incoming CO molecules with the surface OH . radicals on the ice clusters yields the formation of the COOH . radicals via ZPE-corrected energy barriers and reaction energies of about 4-5 kcal mol –1 and –22 kcal mol –1 , respectively. The COOH . radicals couple with incoming NH=CH 2 molecules (experimentally detected in the ISM) to form the NHCH 2 COOH . radical glycine through energy barriers of 12 kcal mol –1 , exceedingly high at ISM cryogenic temperatures. Nonetheless, when H 3 O + is present, one proton may be barrierless transferred to NH=CH 2 to give NH 2 =CH 2 + . This latter may react with the COOH . radical to give the NH 2 CH 2 COOH +. glycine radical cation which can then be transformed into the NH 2 CHC(OH) 2 +. species (the most stable form of glycine in its radical cation state) or into the NH 2 CHCOOH . neutral radical glycine. Estimated rate constants of these events suggest that they are kinetically feasible at temperatures of 100-200 K, which indicate that their occurrence may take place in hot molecular cores or in comets exposed to warmer regions of solar systems. Present results provide quantum chemical evidence that defects formed on water ices due to the harsh-physical conditions of the ISM may trigger reactions of cosmochemical interest. The relevance of surface H 3 O

  9. Computational Study of Interstellar Glycine Formation Occurring at Radical Surfaces of Water-ice Dust Particles

    Science.gov (United States)

    Rimola, Albert; Sodupe, Mariona; Ugliengo, Piero

    2012-07-01

    Glycine is the simplest amino acid, and due to the significant astrobiological implications that suppose its detection, the search for it in the interstellar medium (ISM), meteorites, and comets is intensively investigated. In the present work, quantum mechanical calculations based on density functional theory have been used to model the glycine formation on water-ice clusters present in the ISM. The removal of either one H atom or one electron from the water-ice cluster has been considered to simulate the effect of photolytic radiation and of ionizing particles, respectively, which lead to the formation of OH• radical and H3O+ surface defects. The coupling of incoming CO molecules with the surface OH• radicals on the ice clusters yields the formation of the COOH• radicals via ZPE-corrected energy barriers and reaction energies of about 4-5 kcal mol-1 and -22 kcal mol-1, respectively. The COOH• radicals couple with incoming NH=CH2 molecules (experimentally detected in the ISM) to form the NHCH2COOH• radical glycine through energy barriers of 12 kcal mol-1, exceedingly high at ISM cryogenic temperatures. Nonetheless, when H3O+ is present, one proton may be barrierless transferred to NH=CH2 to give NH2=CH2 +. This latter may react with the COOH• radical to give the NH2CH2COOH+• glycine radical cation which can then be transformed into the NH2CHC(OH)2 +• species (the most stable form of glycine in its radical cation state) or into the NH2CHCOOH• neutral radical glycine. Estimated rate constants of these events suggest that they are kinetically feasible at temperatures of 100-200 K, which indicate that their occurrence may take place in hot molecular cores or in comets exposed to warmer regions of solar systems. Present results provide quantum chemical evidence that defects formed on water ices due to the harsh-physical conditions of the ISM may trigger reactions of cosmochemical interest. The relevance of surface H3O+ ions to facilitate chemical

  10. COMPUTATIONAL STUDY OF INTERSTELLAR GLYCINE FORMATION OCCURRING AT RADICAL SURFACES OF WATER-ICE DUST PARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    Rimola, Albert; Sodupe, Mariona [Departament de Quimica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Ugliengo, Piero, E-mail: albert.rimola@uab.cat [Dipartimento di Chimica, NIS Centre of Excellence and INSTM (Materials and Technology National Consortium), UdR Torino, Universita di Torino, Via P. Giuria 7, 10125 Torino (Italy)

    2012-07-20

    Glycine is the simplest amino acid, and due to the significant astrobiological implications that suppose its detection, the search for it in the interstellar medium (ISM), meteorites, and comets is intensively investigated. In the present work, quantum mechanical calculations based on density functional theory have been used to model the glycine formation on water-ice clusters present in the ISM. The removal of either one H atom or one electron from the water-ice cluster has been considered to simulate the effect of photolytic radiation and of ionizing particles, respectively, which lead to the formation of OH{sup .} radical and H{sub 3}O{sup +} surface defects. The coupling of incoming CO molecules with the surface OH{sup .} radicals on the ice clusters yields the formation of the COOH{sup .} radicals via ZPE-corrected energy barriers and reaction energies of about 4-5 kcal mol{sup -1} and -22 kcal mol{sup -1}, respectively. The COOH{sup .} radicals couple with incoming NH=CH{sub 2} molecules (experimentally detected in the ISM) to form the NHCH{sub 2}COOH{sup .} radical glycine through energy barriers of 12 kcal mol{sup -1}, exceedingly high at ISM cryogenic temperatures. Nonetheless, when H{sub 3}O{sup +} is present, one proton may be barrierless transferred to NH=CH{sub 2} to give NH{sub 2}=CH{sub 2}{sup +}. This latter may react with the COOH{sup .} radical to give the NH{sub 2}CH{sub 2}COOH{sup +.} glycine radical cation which can then be transformed into the NH{sub 2}CHC(OH){sub 2}{sup +.} species (the most stable form of glycine in its radical cation state) or into the NH{sub 2}CHCOOH{sup .} neutral radical glycine. Estimated rate constants of these events suggest that they are kinetically feasible at temperatures of 100-200 K, which indicate that their occurrence may take place in hot molecular cores or in comets exposed to warmer regions of solar systems. Present results provide quantum chemical evidence that defects formed on water ices due to the harsh

  11. Demineralized water flow cancelling experiments with ice plug into high diameter horizontal tube (300 nominal diameter)

    International Nuclear Information System (INIS)

    Gyongyosi, T.; Valeca, S.; Corbescu, B.; Puiu, D.; Panaitescu, V. N.

    2015-01-01

    The isolation with ice plug of a high diameter horizontal pipeline section is a specific technique for repairs activities/ replacements of components owning to thermo-hydraulic installations working with liquid agents. The application of such technique don.t assumes stopping of the entire system. The ice plugging inside of the pipeline assumes using of a special device and of an own specific technology for application. The paper contains a brief description of the experimental technological facilities used, followed by setting off the main moments in evolution of two experimental tests carried out on the test section with 300 mm nominal diameter for demineralized water and, finally, by a brief results analysis and some conclusions. The paper is dedicated to the specialists working in the research and technological engineering. (authors)

  12. Fungal spores as potential ice nuclei in fog/cloud water and snow

    Science.gov (United States)

    Bauer, Heidi; Goncalves, Fabio L. T.; Schueller, Elisabeth; Puxbaum, Hans

    2010-05-01

    INTRODUCTION: In discussions about climate change and precipitation frequency biological ice nucleation has become an issue. While bacterial ice nucleation (IN) is already well characterized and even utilized in industrial processes such as the production of artificial snow or to improve freezing processes in food industry, less is known about the IN potential of fungal spores which are also ubiquitous in the atmosphere. A recent study performed at a mountain top in the Rocky Mountains suggests that fungal spores and/or pollen might play a role in increased IN abundance during periods of cloud cover (Bowers et al. 2009). In the present work concentrations of fungal spores in fog/cloud water and snow were determined. EXPERIMENTAL: Fog samples were taken with an active fog sampler in 2008 in a traffic dominated area and in a national park in São Paulo, Brazil. The number concentrations of fungal spores were determined by microscopic by direct enumeration by epifluorescence microscopy after staining with SYBR Gold nucleic acid gel stain (Bauer et al. 2008). RESULTS: In the fog water collected in the polluted area at a junction of two highly frequented highways around 22,000 fungal spores mL-1 were counted. Fog in the national park contained 35,000 spores mL-1. These results were compared with cloud water and snow samples from Mt. Rax, situated at the eastern rim of the Austrian Alps. Clouds contained on average 5,900 fungal spores mL-1 cloud water (1,300 - 11,000) or 2,200 spores m-3 (304 - 5,000). In freshly fallen snow spore concentrations were lower than in cloud water, around 1,000 fungal spores mL-1 were counted (Bauer et al. 2002). In both sets of samples representatives of the ice nucleating genus Fusarium could be observed. REFERENCES: Bauer, H., Kasper-Giebl, A., Löflund, M., Giebl, H., Hitzenberger, R., Zibuschka, F., Puxbaum, H. (2002). The contribution of bacteria and fungal spores to the organic carbon content of cloud water, precipitation and aerosols

  13. Effects of convective ice evaporation on interannual variability of tropical tropopause layer water vapor

    Science.gov (United States)

    Ye, Hao; Dessler, Andrew E.; Yu, Wandi

    2018-04-01

    Water vapor interannual variability in the tropical tropopause layer (TTL) is investigated using satellite observations and model simulations. We break down the influences of the Brewer-Dobson circulation (BDC), the quasi-biennial oscillation (QBO), and the tropospheric temperature (ΔT) on TTL water vapor as a function of latitude and longitude using a two-dimensional multivariate linear regression. This allows us to examine the spatial distribution of the impact of each process on TTL water vapor. In agreement with expectations, we find that the impacts from the BDC and QBO act on TTL water vapor by changing TTL temperature. For ΔT, we find that TTL temperatures alone cannot explain the influence. We hypothesize a moistening role for the evaporation of convective ice from increased deep convection as the troposphere warms. Tests using a chemistry-climate model, the Goddard Earth Observing System Chemistry Climate Model (GEOSCCM), support this hypothesis.

  14. Amorphous ices explained in terms of nonequilibrium phase transitions in supercooled water

    Science.gov (United States)

    Limmer, David; Chandler, David

    2013-03-01

    We analyze the phase diagram of supercooled water out-of-equilibrium using concepts from space-time thermodynamics and the dynamic facilitation theory of the glass transition, together with molecular dynamics simulations. We find that when water is driven out-of-equilibrium, it can exist in multiple amorphous states. In contrast, we find that when water is at equilibrium, it can exist in only one liquid state. The amorphous non-equilibrium states are solids, distinguished from the liquid by their lack of mobility, and distinguished from each other by their different densities and local structure. This finding explains the experimentally observed polyamorphism of water as a class of nonequilibrium phenomena involving glasses of different densities. While the amorphous solids can be long lived, they are thermodynamically unstable. When allowed to relax to equilibrium, they crystallize with pathways that pass first through liquid state configurations and then to ordered ice.

  15. McCall Glacier record of Arctic climate change: Interpreting a northern Alaska ice core with regional water isotopes

    Science.gov (United States)

    Klein, E. S.; Nolan, M.; McConnell, J.; Sigl, M.; Cherry, J.; Young, J.; Welker, J. M.

    2016-01-01

    We explored modern precipitation and ice core isotope ratios to better understand both modern and paleo climate in the Arctic. Paleoclimate reconstructions require an understanding of how modern synoptic climate influences proxies used in those reconstructions, such as water isotopes. Therefore we measured periodic precipitation samples at Toolik Lake Field Station (Toolik) in the northern foothills of the Brooks Range in the Alaskan Arctic to determine δ18O and δ2H. We applied this multi-decadal local precipitation δ18O/temperature regression to ∼65 years of McCall Glacier (also in the Brooks Range) ice core isotope measurements and found an increase in reconstructed temperatures over the late-20th and early-21st centuries. We also show that the McCall Glacier δ18O isotope record is negatively correlated with the winter bidecadal North Pacific Index (NPI) climate oscillation. McCall Glacier deuterium excess (d-excess, δ2H - 8*δ18O) values display a bidecadal periodicity coherent with the NPI and suggest shifts from more southwestern Bering Sea moisture sources with less sea ice (lower d-excess values) to more northern Arctic Ocean moisture sources with more sea ice (higher d-excess values). Northern ice covered Arctic Ocean McCall Glacier moisture sources are associated with weak Aleutian Low (AL) circulation patterns and the southern moisture sources with strong AL patterns. Ice core d-excess values significantly decrease over the record, coincident with warmer temperatures and a significant reduction in Alaska sea ice concentration, which suggests that ice free northern ocean waters are increasingly serving as terrestrial precipitation moisture sources; a concept recently proposed by modeling studies and also present in Greenland ice core d-excess values during previous transitions to warm periods. This study also shows the efficacy and importance of using ice cores from Arctic valley glaciers in paleoclimate reconstructions.

  16. An Assessment of the Icing Blade and the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

    Science.gov (United States)

    Steen, Laura E.; Ide, Robert F.; Van Zante, Judith Foss

    2017-01-01

    The Icing Research Tunnel at NASA Glenn has recently switched to from using the Icing Blade to using the SEA Multi-Element Sensor (also known as the multi-wire) for its calibration of cloud liquid water content. In order to perform this transition, tests were completed to compare the Multi-Element Sensor to the Icing Blade, particularly with respect to liquid water content, airspeed, and drop size. The two instruments were found to compare well for the majority of Appendix C conditions. However, it was discovered that the Icing Blade under-measures when the conditions approach the Ludlam Limit. This paper also describes data processing procedures for the Multi-Element Sensor in the IRT, including collection efficiency corrections, mounting underneath a splitter plate, and correcting for a jump in the compensation wire power. Further data is presented to describe the repeatability of the IRT with the Multi-Element sensor, health-monitoring checks for the instrument, and a sensing-element configuration comparison.

  17. Salt partitioning between water and high-pressure ices. Implication for the dynamics and habitability of icy moons and water-rich planetary bodies

    Science.gov (United States)

    Journaux, Baptiste; Daniel, Isabelle; Petitgirard, Sylvain; Cardon, Hervé; Perrillat, Jean-Philippe; Caracas, Razvan; Mezouar, Mohamed

    2017-04-01

    Water-rich planetary bodies including large icy moons and ocean exoplanets may host a deep liquid water ocean underlying a high-pressure icy mantle. The latter is often considered as a limitation to the habitability of the uppermost ocean because it would limit the availability of nutrients resulting from the hydrothermal alteration of the silicate mantle located beneath the deep ice layer. To assess the effects of salts on the physical properties of high-pressure ices and therefore the possible chemical exchanges and habitability inside H2O-rich planetary bodies, we measured partitioning coefficients and densities in the H2O-RbI system up to 450 K and 4 GPa; RbI standing as an experimentally amenable analog of NaCl in the H2O-salt solutions. We measured the partitioning coefficient of RbI between the aqueous fluid and ices VI and VII, using in-situ Synchrotron X-ray Fluorescence (XRF). With in-situ X-ray diffraction, we measured the unit-cell parameters and the densities of the high-pressure ice phases in equilibrium with the aqueous fluid, at pressures and temperatures relevant to the interior of planetary bodies. We conclude that RbI is strongly incompatible towards ice VI with a partitioning coefficient Kd(VI-L) = 5.0 (± 2.1) ṡ10-3 and moderately incompatible towards ice VII, Kd(VII-L) = 0.12 (± 0.05). RbI significantly increases the unit-cell volume of ice VI and VII by ca. 1%. This implies that RbI-poor ice VI is buoyant compared to H2O ice VI while RbI-enriched ice VII is denser than H2O ice VII. These new experimental results might profoundly impact the internal dynamics of water-rich planetary bodies. For instance, an icy mantle at moderate conditions of pressure and temperature will consist of buoyant ice VI with low concentration of salt, and would likely induce an upwelling current of solutes towards the above liquid ocean. In contrast, a deep and/or thick icy mantle of ice VII will be enriched in salt and hence would form a stable chemical boundary

  18. Ergogenic effects of precooling with cold water immersion and ice ingestion: A meta-analysis.

    Science.gov (United States)

    Choo, Hui C; Nosaka, Kazunori; Peiffer, Jeremiah J; Ihsan, Mohammed; Abbiss, Chris R

    2018-03-01

    This review evaluated the effects of precooling via cold water immersion (CWI) and ingestion of ice slurry/slushy or crushed ice (ICE) on endurance performance measures (e.g. time-to-exhaustion and time trials) and psychophysiological parameters (core [T core ] and skin [T skin ] temperatures, whole body sweat [WBS] response, heart rate [HR], thermal sensation [TS], and perceived exertion [RPE]). Twenty-two studies were included in the meta-analysis based on the following criteria: (i) cooling was performed before exercise with ICE or CWI; (ii) exercise longer than 6 min was performed in ambient temperature ≥26°C; and (iii) crossover study design with a non-cooling passive control condition. CWI improved performance measures (weighted average effect size in Hedges' g [95% confidence interval] + 0.53 [0.28; 0.77]) and resulted in greater increase (ΔEX) in T skin (+4.15 [3.1; 5.21]) during exercise, while lower peak T core (-0.93 [-1.18; -0.67]), WBS (-0.74 [-1.18; -0.3]), and TS (-0.5 [-0.8; -0.19]) were observed without concomitant changes in ΔEX-T core (+0.19 [-0.22; 0.6]), peak T skin (-0.67 [-1.52; 0.18]), peak HR (-0.14 [-0.38; 0.11]), and RPE (-0.14 [-0.39; 0.12]). ICE had no clear effect on performance measures (+0.2 [-0.07; 0.46]) but resulted in greater ΔEX-T core (+1.02 [0.59; 1.45]) and ΔEX-T skin (+0.34 [0.02; 0.67]) without concomitant changes in peak T core (-0.1 [-0.48; 0.28]), peak T skin (+0.1 [-0.22; 0.41]), peak HR (+0.08 [-0.19; 0.35]), WBS (-0.12 [-0.42; 0.18]), TS (-0.2 [-0.49; 0.1]), and RPE (-0.01 [-0.33; 0.31]). From both ergogenic and thermoregulatory perspectives, CWI may be more effective than ICE as a precooling treatment prior to exercise in the heat.

  19. Cordilleran Ice Sheet meltwater delivery to the coastal waters of the northeast Pacific Ocean

    Science.gov (United States)

    Hendy, I. L.; Taylor, M.; Gombiner, J. H.; Hemming, S. R.; Bryce, J. G.; Blichert-Toft, J.

    2014-12-01

    Cordilleran Ice Sheet (CIS) delivered meltwater to the NE Pacific Ocean off BC and WA via glacial lake outburst floods (GLOFs), ice rafting and subglacial meltwater discharge. A deglacial glaciomarine sedimentation record is preserved in the well dated ~50-kyr core MD02-2496 (48˚58.47' N, 127˚02.14' W, water depth 1243 m), collected off Vancouver Island. To understand the history of the relationship between the CIS, climate and meltwater discharge, high resolution, multi-proxy geochemical records from the interval that captures the Fraser Glaciation (~30-10 ka) were generated. These proxies include Mg/Ca temperatures and δ18Oseawater from planktonic foraminiferal sp. N. pachyderma and G. bulloides, elemental and organic carbon (Corg) geochemistry of bulk sediments, ɛNd and K/Ar dating of the rose by > 3°C to 10-12°C in association with an additional IRD event at ~14.8 ka sourced from a ~75 Ma felsic volcanic source, likely the Southern Coast Plutonic Complex. At no point in the δ18Oseawater reconstruction is an obvious meltwater isotopic signature recorded despite the sedimentary evidence for both ice rafting and outburst flooding. Thus CIS meltwater likely entered the NE Pacific Ocean via hyperpycnal flow.

  20. Regions of open water and melting sea ice drive new particle formation in North East Greenland.

    Science.gov (United States)

    Dall Osto, M; Geels, C; Beddows, D C S; Boertmann, D; Lange, R; Nøjgaard, J K; Harrison, Roy M; Simo, R; Skov, H; Massling, A

    2018-04-17

    Atmospheric new particle formation (NPF) and growth significantly influences the indirect aerosol-cloud effect within the polar climate system. In this work, the aerosol population is categorised via cluster analysis of aerosol number size distributions (9-915 nm, 65 bins) taken at Villum Research Station, Station Nord (VRS) in North Greenland during a 7 year record (2010-2016). Data are clustered at daily averaged resolution; in total, we classified six categories, five of which clearly describe the ultrafine aerosol population, one of which is linked to nucleation events (up to 39% during summer). Air mass trajectory analyses tie these frequent nucleation events to biogenic precursors released by open water and melting sea ice regions. NPF events in the studied regions seem not to be related to bird colonies from coastal zones. Our results show a negative correlation (r = -0.89) between NPF events and sea ice extent, suggesting the impact of ultrafine Arctic aerosols is likely to increase in the future, given the likely increased sea ice melting. Understanding the composition and the sources of Arctic aerosols requires further integrated studies with joint multi-component ocean-atmosphere observation and modelling.

  1. Water, ice, and meteorological measurements at South Cascade glacier, Washington, balance year 2003

    Science.gov (United States)

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2005-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass-balance quantities for balance year 2003. The 2003 glacier-average maximum winter snow balance was 2.66 meters water equivalent, which was about equal to the average of such balances for the glacier since balance year 1959. The 2003 glacier summer balance (-4.76 meters water equivalent) was the most negative reported for the glacier, and the 2003 net balance (-2.10 meters water equivalent), was the second-most negative reported. The glacier 2003 annual (water year) balance was -1.89 meters water equivalent. The area of the glacier near the end of the balance year was 1.89 square kilometers, a decrease of 0.03 square kilometer from the previous year. The equilibrium-line altitude was higher than any part of the glacier; however, because snow remained along part of one side of the upper glacier, the accumulation-area ratio was 0.07. During September 13, 2002-September 13, 2003, the glacier terminus retreated at a rate of about 15 meters per year. Average speed of surface ice, computed using a series of vertical aerial photographs dating back to 2001, ranged from 2.2 to 21.8 meters per year. Runoff from the subbasin containing the glacier and from an adjacent non-glacierized basin was gaged during part of water year 2003. Air temperature, precipitation, atmospheric water-vapor pressure, wind speed, and incoming solar radiation were measured at selected locations on and near the glacier. Summer 2003 at the glacier was among the warmest for which data are available.

  2. Sea ice - Multiyear cycles and white ice

    Science.gov (United States)

    Ledley, T. S.

    1985-01-01

    The multiyear thickness cycles represent one of the interesting features of the sea ice studies performed by Semtner (1976) and Washington et al. (1976) with simple thermodynamic models of sea ice. In the present article, a description is given of results which show that the insulating effect of snow on the surface of the sea ice is important in producing these multiyear cycles given the physics included in the model. However, when the formation of white ice is included, the cycles almost disappear. White ice is the ice which forms at the snow-ice interface when the snow layer becomes thick enough to depress the ice below the water level. Water infiltrates the snow by coming through the ice at leads and generally freezes there, forming white ice.

  3. Vulnerability of Southeast Greenland Glaciers to Warm Atlantic Water From Operation IceBridge and Ocean Melting Greenland Data

    Science.gov (United States)

    Millan, R.; Rignot, E.; Mouginot, J.; Wood, M.; Bjørk, A. A.; Morlighem, M.

    2018-03-01

    We employ National Aeronautics and Space Administration (NASA)'s Operation IceBridge high-resolution airborne gravity from 2016, NASA's Ocean Melting Greenland bathymetry from 2015, ice thickness from Operation IceBridge from 2010 to 2015, and BedMachine v3 to analyze 20 major southeast Greenland glaciers. The results reveal glacial fjords several hundreds of meters deeper than previously thought; the full extent of the marine-based portions of the glaciers; deep troughs enabling warm, salty Atlantic Water (AW) to reach the glacier fronts and melt them from below; and few shallow sills that limit the access of AW. The new oceanographic and topographic data help to fully resolve the complex pattern of historical ice front positions from the 1930s to 2017: glaciers exposed to AW and resting on retrograde beds have retreated rapidly, while glaciers perched on shallow sills or standing in colder waters or with major sills in the fjords have remained stable.

  4. The Longevity of Water Ice on Ganymedes and Europas around Migrated Giant Planets

    International Nuclear Information System (INIS)

    Lehmer, Owen R.; Catling, David C.; Zahnle, Kevin J.

    2017-01-01

    The gas giant planets in the Solar System have a retinue of icy moons, and we expect giant exoplanets to have similar satellite systems. If a Jupiter-like planet were to migrate toward its parent star the icy moons orbiting it would evaporate, creating atmospheres and possible habitable surface oceans. Here, we examine how long the surface ice and possible oceans would last before being hydrodynamically lost to space. The hydrodynamic loss rate from the moons is determined, in large part, by the stellar flux available for absorption, which increases as the giant planet and icy moons migrate closer to the star. At some planet–star distance the stellar flux incident on the icy moons becomes so great that they enter a runaway greenhouse state. This runaway greenhouse state rapidly transfers all available surface water to the atmosphere as vapor, where it is easily lost from the small moons. However, for icy moons of Ganymede’s size around a Sun-like star we found that surface water (either ice or liquid) can persist indefinitely outside the runaway greenhouse orbital distance. In contrast, the surface water on smaller moons of Europa’s size will only persist on timescales greater than 1 Gyr at distances ranging 1.49–0.74 au around a Sun-like star for Bond albedos of 0.2 and 0.8, where the lower albedo becomes relevant if ice melts. Consequently, small moons can lose their icy shells, which would create a torus of H atoms around their host planet that might be detectable in future observations.

  5. The Longevity of Water Ice on Ganymedes and Europas around Migrated Giant Planets

    Energy Technology Data Exchange (ETDEWEB)

    Lehmer, Owen R.; Catling, David C. [Dept. of Earth and Space Sciences/Astrobiology Program, University of Washington, Seattle, WA (United States); Zahnle, Kevin J., E-mail: olehmer@gmail.com [NASA Ames Research Center, Moffett Field, CA (United States)

    2017-04-10

    The gas giant planets in the Solar System have a retinue of icy moons, and we expect giant exoplanets to have similar satellite systems. If a Jupiter-like planet were to migrate toward its parent star the icy moons orbiting it would evaporate, creating atmospheres and possible habitable surface oceans. Here, we examine how long the surface ice and possible oceans would last before being hydrodynamically lost to space. The hydrodynamic loss rate from the moons is determined, in large part, by the stellar flux available for absorption, which increases as the giant planet and icy moons migrate closer to the star. At some planet–star distance the stellar flux incident on the icy moons becomes so great that they enter a runaway greenhouse state. This runaway greenhouse state rapidly transfers all available surface water to the atmosphere as vapor, where it is easily lost from the small moons. However, for icy moons of Ganymede’s size around a Sun-like star we found that surface water (either ice or liquid) can persist indefinitely outside the runaway greenhouse orbital distance. In contrast, the surface water on smaller moons of Europa’s size will only persist on timescales greater than 1 Gyr at distances ranging 1.49–0.74 au around a Sun-like star for Bond albedos of 0.2 and 0.8, where the lower albedo becomes relevant if ice melts. Consequently, small moons can lose their icy shells, which would create a torus of H atoms around their host planet that might be detectable in future observations.

  6. Towards a probabilistic model for predicting ship besetting in ice in Arctic waters

    International Nuclear Information System (INIS)

    Fu, Shanshan; Zhang, Di; Montewka, Jakub; Yan, Xinping; Zio, Enrico

    2016-01-01

    Recently, the melting of sea ice due to global warming has made it possible for merchant ships to navigate through Arctic Waters. However, Arctic Marine Transportation System remains a very demanding, dynamic and complex system due to challenging hydro-meteorological conditions, poorly charted waters and remoteness of the area resulting in lack of appropriate response capacity in case of emergency. In order to ensure a proper safety level for operations such as ship transit within the area, a risk analysis should be carried out, where the relevant factors pertaining to a given operation are defined and organized in a model. Such a model can assist onshore managers or ships’ crews in planning and conducting an actual sea passage through Arctic waters. However, research in this domain is scarce, mainly due to lack of data. In this paper, we demonstrate the use of a dataset and expert judgment to determine the risk influencing factors and develop a probabilistic model for a ship besetting in ice along the Northeast Passage. For that purpose, we adopt Bayesian belief Networks (BBNs), due to their predominant feature of reasoning under uncertainty and their ability to accommodate data from various sources. The obtained BBN model has been validated showing good agreement with available state-of-the-art models, and providing good understanding of the analyzed phenomena.

  7. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, balance year 2002

    Science.gov (United States)

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2004-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass balance quantities for balance year 2002. The 2002 glacier-average maximum winter snow balance was 4.02 meters, the second largest since 1959. The 2002 glacier summer, net, and annual (water year) balances were -3.47, 0.55, and 0.54 meters, respectively. The area of the glacier near the end of the balance year was 1.92 square kilometers, and the equilibrium-line altitude and the accumulation area ratio were 1,820 meters and 0.84, respectively. During September 20, 2001 to September 13, 2002, the terminus retreated 4 meters, and computed average ice speeds in the ablation area ranged from 7.8 to 20.7 meters per year. Runoff from the subbasin containing the glacier and from an adjacent non-glacierized basin were measured during part of the 2002 water year. Air temperature, precipitation, atmospheric water-vapor pressure, wind speed and incoming solar radiation were measured at selected locations near the glacier.

  8. Correlation between thermodynamic anomalies and pathways of ice nucleation in supercooled water

    International Nuclear Information System (INIS)

    Singh, Rakesh S.; Bagchi, Biman

    2014-01-01

    The well-known classical nucleation theory (CNT) for the free energy barrier towards formation of a nucleus of critical size of the new stable phase within the parent metastable phase fails to take into account the influence of other metastable phases having density/order intermediate between the parent metastable phase and the final stable phase. This lacuna can be more serious than capillary approximation or spherical shape assumption made in CNT. This issue is particularly significant in ice nucleation because liquid water shows rich phase diagram consisting of two (high and low density) liquid phases in supercooled state. The explanations of thermodynamic and dynamic anomalies of supercooled water often invoke the possible influence of a liquid-liquid transition between two metastable liquid phases. To investigate both the role of thermodynamic anomalies and presence of distinct metastable liquid phases in supercooled water on ice nucleation, we employ density functional theoretical approach to find nucleation free energy barrier in different regions of phase diagram. The theory makes a number of striking predictions, such as a dramatic lowering of nucleation barrier due to presence of a metastable intermediate phase and crossover in the dependence of free energy barrier on temperature near liquid-liquid critical point. These predictions can be tested by computer simulations as well as by controlled experiments

  9. Complex astrophysical experiments relating to jets, solar loops, and water ice dusty plasma

    Science.gov (United States)

    Bellan, P. M.; Zhai, X.; Chai, K. B.; Ha, B. N.

    2015-10-01

    > Recent results of three astrophysically relevant experiments at Caltech are summarized. In the first experiment magnetohydrodynamically driven plasma jets simulate astrophysical jets that undergo a kink instability. Lateral acceleration of the kinking jet spawns a Rayleigh-Taylor instability, which in turn spawns a magnetic reconnection. Particle heating and a burst of waves are observed in association with the reconnection. The second experiment uses a slightly different setup to produce an expanding arched plasma loop which is similar to a solar corona loop. It is shown that the plasma in this loop results from jets originating from the electrodes. The possibility of a transition from slow to fast expansion as a result of the expanding loop breaking free of an externally imposed strapping magnetic field is investigated. The third and completely different experiment creates a weakly ionized plasma with liquid nitrogen cooled electrodes. Water vapour injected into this plasma forms water ice grains that in general are ellipsoidal and not spheroidal. The water ice grains can become quite long (up to several hundred microns) and self-organize so that they are evenly spaced and vertically aligned.

  10. Very high elevation water ice clouds on Mars: Their morphology and temporal behavior

    Science.gov (United States)

    Jaquin, Fred

    1988-01-01

    Quantitative analysis of Viking images of the martian planetary limb has uncovered the existence and temporal behavior of water ice clouds that form between 50 and 90 km elevation. These clouds show a seasonal behavior that may be correlated with lower atmosphere dynamics. Enhanced vertical mixing of the atmosphere as Mars nears perihelion is hypothesized as the cause of the seasonal dependence, and the diurnal dependence is explained by the temporal behavior of the martian diurnal thermal tide. Viking images also provide a data set of the vertical distribution of aerosols in the martian atmosphere. The temporal and spatial distribution of aerosols are characterized.

  11. The Inferred Distribution of Liquid Water in Europa's Ice Shell: Implications for the Europa Lander Mission

    Science.gov (United States)

    Noviello, J. L.; Torrano, Z. A.; Rhoden, A.; Manga, M.

    2017-12-01

    A key objective of the Europa lander mission is to identify liquid water within 30 km of the lander (Europa Lander SDT report, 2017), to provide essential context with which to evaluate samples and enable assessment of Europa's overall habitability. To inform lander mission development, we utilize a model of surface feature formation that invokes liquid water within Europa's ice shell to map out the implied 3D distribution of liquid water and assess the likelihood of a lander to be within 30 km of liquid water given regional variability. Europa's surface displays a variety of microfeatures, also called lenticulae, including pits, domes, spots, and microchaos. A recent model by Manga and Michaut (2017) attributes these features to various stages in the thermal-mechanical evolution of liquid water intrusions (i.e. sills) within the ice shell, from sill emplacement to surface breaching (in the case of microchaos) to freezing of the sill. Pits are of particular interest because they appear only when liquid water is still present. Another key feature of the model is that the size of a microfeature at the surface is controlled by the depth of the sill. Hence, we can apply this model to regions of Europa that contain microfeatures to infer the size, depth, and spatial distribution of liquid water within the ice shell. We are creating a database of microfeatures that includes digitized, collated data from previous mapping efforts along with our own mapping study. We focus on images with 220 m/pixel resolution, which includes the regional mapping data sets. Analysis of a preliminary study area suggests that sills are typically located at depths of 2km or less from the surface. We will present analysis of the full database of microfeatures and the corresponding 3D distribution of sills implied by the model. Our preliminary analysis also shows that pits are clustered in some regions, consistent with previous results, although individual pits are also observed. We apply a

  12. Simultaneous measurement of unfrozen water content and ice content in frozen soil using gamma ray attenuation and TDR

    Science.gov (United States)

    Zhou, Xiaohai; Zhou, Jian; Kinzelbach, Wolfgang; Stauffer, Fritz

    2014-12-01

    The freezing temperature of water in soil is not constant but varies over a range determined by soil texture. Consequently, the amounts of unfrozen water and ice change with temperature in frozen soil, which in turn affects hydraulic, thermal, and mechanical properties of frozen soil. In this paper, an Am-241 gamma ray source and time-domain reflectometry (TDR) were combined to measure unfrozen water content and ice content in frozen soil simultaneously. The gamma ray attenuation was used to determine total water content. The TDR was used to determine the dielectric constant of the frozen soil. Based on a four-phase mixing model, the amount of unfrozen water content in the frozen soil could be determined. The ice content was inferred by the difference between total water content and unfrozen water content. The gamma ray attenuation and the TDR were both calibrated by a gravimetric method. Water contents measured by gamma ray attenuation and TDR in an unfrozen silt column under infiltration were compared and showed that the two methods have the same accuracy and response to changes of water content. Unidirectional column freezing experiments were performed to apply the combined method of gamma ray attenuation and TDR for measuring unfrozen water content and ice content. The measurement error of the gamma ray attenuation and TDR was around 0.02 and 0.01 m3/m3, respectively. The overestimation of unfrozen water in frozen soil by TDR alone was quantified and found to depend on the amount of ice content. The higher the ice content, the larger the overestimation. The study confirmed that the combined method could accurately determine unfrozen water content and ice content in frozen soil. The results of soil column freezing experiments indicate that total water content distribution is affected by available pore space and the freezing front advance rate. It was found that there is similarity between the soil water characteristic and the soil freezing characteristic of

  13. Relationship between ice water path and downward longwave radiation for clouds optically thin in the infrared: Observations and model calculations

    Science.gov (United States)

    Uttal, Taneil; Matrosov, Sergey Y.; Snider, Jack B.; Kropfli, Robert A.

    1994-01-01

    A vertically pointing 3.2-cm radar is used to observe altostratus and cirrus clouds as they pass overhead. Radar reflectivities are used in combination with an empirical Z(sub i)-IWC (ice water content) relationship developed by Sassen (1987) to parameterize IWC, which is then integrated to obtain estimates of ice water path (IWP). The observed dataset is segregated into all-ice and mixed-phase periods using measurements of integrated liquid water paths (LWP) detected by a collocated, dual-channel microwave radiometer. The IWP values for the all ice periods are compared to measurements of infrared (IR) downward fluxes measured by a collocated narrowband (9.95-11.43 microns) IR radiometer, which results in scattergrams representing the observed dependence of IR fluxes on IWP. A two-stream model is used to calculate the infrared fluxes expected from ice clouds with boundary conditions specified by the actual clouds, and similar curves relating IWP and infrared fluxes are obtained. The model and observational results suggest that IWP is one of the primary controls on infrared thermal fluxes for ice clouds.

  14. Adsorption and structure of water on kaolinite surfaces: possible insight into ice nucleation from grand canonical monte carlo calculations.

    Science.gov (United States)

    Croteau, T; Bertram, A K; Patey, G N

    2008-10-30

    Grand canonical Monte Carlo calculations are used to determine water adsorption and structure on defect-free kaolinite surfaces as a function of relative humidity at 235 K. This information is then used to gain insight into ice nucleation on kaolinite surfaces. Results for both the SPC/E and TIP5P-E water models are compared and demonstrate that the Al-surface [(001) plane] and both protonated and unprotonated edges [(100) plane] strongly adsorb at atmospherically relevant relative humidities. Adsorption on the Al-surface exhibits properties of a first-order process with evidence of collective behavior, whereas adsorption on the edges is essentially continuous and appears dominated by strong water lattice interactions. For the protonated and unprotonated edges no structure that matches hexagonal ice is observed. For the Al-surface some of the water molecules formed hexagonal rings. However, the a o lattice parameter for these rings is significantly different from the corresponding constant for hexagonal ice ( Ih). A misfit strain of 14.0% is calculated between the hexagonal pattern of water adsorbed on the Al-surface and the basal plane of ice Ih. Hence, the ring structures that form on the Al-surface are not expected to be good building-blocks for ice nucleation due to the large misfit strain.

  15. Freshwater ice as habitat: partitioning of phytoplankton and bacteria between ice and water in central European reservoirs

    Czech Academy of Sciences Publication Activity Database

    McKay, R.M.L.; Prášil, Ondřej; Pechar, L.; Lawrenz, Evelyn; Rozmarynowycz, M.; Bullerjahn, G. S.

    2015-01-01

    Roč. 7, č. 6 (2015), s. 887-898 ISSN 1758-2229 R&D Projects: GA MŠk LO1416; GA MŠk EE2.3.30.0059 Institutional support: RVO:61388971 Keywords : COVERED LAKE-ERIE * ANTARCTIC SEA-ICE * LONG-TERM CHANGES Subject RIV: EE - Microbiology, Virology Impact factor: 3.500, year: 2015

  16. Diazotroph Diversity in the Sea Ice, Melt Ponds, and Surface Waters of the Eurasian Basin of the Central Arctic Ocean.

    Science.gov (United States)

    Fernández-Méndez, Mar; Turk-Kubo, Kendra A; Buttigieg, Pier L; Rapp, Josephine Z; Krumpen, Thomas; Zehr, Jonathan P; Boetius, Antje

    2016-01-01

    The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

  17. Diazotroph diversity in the sea ice, melt ponds and surface waters of the Eurasian Basin of the Central Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Mar Fernández-Méndez

    2016-11-01

    Full Text Available The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing towards a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77ºN. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

  18. Determining ice water content from 2D crystal images in convective cloud systems

    Science.gov (United States)

    Leroy, Delphine; Coutris, Pierre; Fontaine, Emmanuel; Schwarzenboeck, Alfons; Strapp, J. Walter

    2016-04-01

    Cloud microphysical in-situ instrumentation measures bulk parameters like total water content (TWC) and/or derives particle size distributions (PSD) (utilizing optical spectrometers and optical array probes (OAP)). The goal of this work is to introduce a comprehensive methodology to compute TWC from OAP measurements, based on the dataset collected during recent HAIC (High Altitude Ice Crystals)/HIWC (High Ice Water Content) field campaigns. Indeed, the HAIC/HIWC field campaigns in Darwin (2014) and Cayenne (2015) provide a unique opportunity to explore the complex relationship between cloud particle mass and size in ice crystal environments. Numerous mesoscale convective systems (MCSs) were sampled with the French Falcon 20 research aircraft at different temperature levels from -10°C up to 50°C. The aircraft instrumentation included an IKP-2 (isokinetic probe) to get reliable measurements of TWC and the optical array probes 2D-S and PIP recording images over the entire ice crystal size range. Based on the known principle relating crystal mass and size with a power law (m=α•Dβ), Fontaine et al. (2014) performed extended 3D crystal simulations and thereby demonstrated that it is possible to estimate the value of the exponent β from OAP data, by analyzing the surface-size relationship for the 2D images as a function of time. Leroy et al. (2015) proposed an extended version of this method that produces estimates of β from the analysis of both the surface-size and perimeter-size relationships. Knowing the value of β, α then is deduced from the simultaneous IKP-2 TWC measurements for the entire HAIC/HIWC dataset. The statistical analysis of α and β values for the HAIC/HIWC dataset firstly shows that α is closely linked to β and that this link changes with temperature. From these trends, a generalized parameterization for α is proposed. Finally, the comparison with the initial IKP-2 measurements demonstrates that the method is able to predict TWC values

  19. Dielectric constant and low-frequency infrared spectra for liquid water and ice Ih within the E3B model

    Energy Technology Data Exchange (ETDEWEB)

    Shi, L.; Ni, Y.; Drews, S. E. P.; Skinner, J. L. [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

    2014-08-28

    Two intrinsic difficulties in modeling condensed-phase water with conventional rigid non-polarizable water models are: reproducing the static dielectric constants for liquid water and ice Ih, and generating the peak at about 200 cm{sup −1} in the low-frequency infrared spectrum for liquid water. The primary physical reason for these failures is believed to be the missing polarization effect in these models, and consequently various sophisticated polarizable water models have been developed. However, in this work we pursue a different strategy and propose a simple empirical scheme to include the polarization effect only on the dipole surface (without modifying a model's intermolecular interaction potential). We implement this strategy for our explicit three-body (E3B) model. Our calculated static dielectric constants and low-frequency infrared spectra are in good agreement with experiment for both liquid water and ice Ih over wide temperature ranges, albeit with one fitting parameter for each phase. The success of our modeling also suggests that thermal fluctuations about local minima and the energy differences between different proton-disordered configurations play minor roles in the static dielectric constant of ice Ih. Our analysis shows that the polarization effect is important in resolving the two difficulties mentioned above and sheds some light on the origin of several features in the low-frequency infrared spectra for liquid water and ice Ih.

  20. Use of water stable isotopes in climatology and paleoclimatology illustrated from polar ice cores studies

    International Nuclear Information System (INIS)

    Jouzel, J.; Lorius, C.

    1994-01-01

    The isotopic content of ancient waters (deuterium and oxygen 18) gives a key access to past climatic changes. An essentially linear relationship exists between the isotopic content of a precipitation and the temperature of the site (at least for medium and high latitudes). This link between water isotope atmospheric cycle and climate is presented through various isotopic models and illustrated from the deuterium profile obtained along the Vostok ice core in East Antarctica. This 2 km record which covers a full glacial-interglacial cycle (160000 years) confirms the existence of a link between insolation changes and climate (Milankovitch theory). It shows also that the greenhouse effect has played a role in glacial-interglacial changes in amplifying this orbital forcing. (authors). 10 figs., 23 refs

  1. Changes of brachial arterial doppler waveform during immersion of the hand of young men in ice-cold water

    International Nuclear Information System (INIS)

    Kim, Young Goo

    1994-01-01

    To evaluate the changes of brachial arterial Doppler waveform during immersion of the hand of young men in ice-cold water. Doppler waveforms of brachial arteries in 11 young male patients were recorded before and during immersion of ipsilateral hand in ice-cold water(4-5 .deg. C). The procedure was repeated on separate days. Patterns of waveform during immersion were compared with the changes of pulsatility index. Four men showed high impedance waveforms, and 5 men showed low impedance waveforms during immersion both at the first and at the second study. Two men, however, showed high impedance waveforms at the first study and tow impedance waveforms at the second study. The pulsatility index rose and fell in high and low impedance waveforms, respectively. The changes of brachial arterial Doppler waveforms could be classified into high and low impedance patterns, probably reflecting the acute changes in downstream impedance during immersion of hand in ice-cold water

  2. Raman lidar measurement of water vapor and ice clouds associated with Asian dust layer over Tsukuba, Japan

    Science.gov (United States)

    Sakai, Tetsu; Nagai, Tomohiro; Nakazato, Masahisa; Matsumura, Takatsugu

    2004-03-01

    The vertical distributions of particle extinction, backscattering, depolarization, and water vapor mixing ratio were measured using a Raman lidar over Tsukuba (36.1°N, 140.1°E), Japan, on 23-24 April 2001. Ice clouds associated with the Asian dust layer were observed at an altitude of ~6-9 km. The relative humidities in the cloud layer were close to the ice saturation values and the temperature at the top of the cloud layer was ~-35°C, suggesting that the Asian dust acted as ice nuclei at the high temperatures. The meteorological analysis suggested that the ice-saturated region was formed near the top of the dust layer where the moist air ascended in slantwise fashion above the cold-frontal zone associated with extratropical cyclone.

  3. Preparation of water and ice samples for 39Ar dating by atom trap trace analysis (ATTA)

    Science.gov (United States)

    Schwefel, R.; Reichel, T.; Aeschbach-Hertig, W.; Wagenbach, D.

    2012-04-01

    Atom trap trace analysis (ATTA) is a new and promising method to measure very rare noble gas radioisotopes in the environment. The applicability of this method for the dating of very old groundwater with 81Kr has already been demonstrated [1]. Recent developments now show its feasibility also for the analysis of 39Ar [2,3], which is an ideal dating tracer for the age range between 50 and 1000 years. This range is of interest in the fields of hydro(geo)logy, oceanography, and glaciology. We present preparation (gas extraction and Ar separation) methods for groundwater and ice samples for later analysis by the ATTA technique. For groundwater, the sample size is less of a limitation than for applications in oceanography or glaciology. Large samples are furthermore needed to enable a comparison with the classical method of 39Ar detection by low-level counting. Therefore, a system was built that enables gas extraction from several thousand liters of water using membrane contactors. This system provides degassing efficiencies greater than 80 % and has successfully been tested in the field. Gas samples are further processed to separate a pure Ar fraction by a gas-chromatographic method based on Li-LSX zeolite as selective adsorber material at very low temperatures. The gas separation achieved by this system is controlled by a quadrupole mass spectrometer. It has successfully been tested and used on real samples. The separation efficiency was found to be strongly temperature dependent in the range of -118 to -130 °C. Since ATTA should enable the analysis of 39Ar on samples of less than 1 ccSTP of Ar (corresponding to about 100 ml of air, 2.5 l of water or 1 kg of ice), a method to separate Ar from small amounts of gas was developed. Titanium sponge was found to absorb 60 ccSTP of reactive gases per g of the getter material with reasonably high absorption rates at high operating temperatures (~ 800 ° C). Good separation (higher than 92 % Ar content in residual gas) was

  4. Azimuthal Structure of the Sand Erg that Encircles the North Polar Water-Ice Cap

    Science.gov (United States)

    Teodoro, L. A.; Elphic, R. C.; Eke, V. R.; Feldman, W. C.; Maurice, S.; Pathare, A.

    2011-12-01

    The sand erg that completely encircles the perennial water-ice cap that covers the Martian north geographic pole displays considerable azimuthal structure as seen in visible and near-IR images. Much of this structure is associated with the terminations of the many steep troughs that cut spiral the approximately 3 km thick polar ice cap. Other contributions come from the katabatic winds that spill over steep-sided edges of the cap, such as what bounds the largest set of dunes that comprise Olympia Undae. During the spring and summer months when these winds initiate from the higher altitudes that contain sublimating CO2 ice, which is very cold and dry, heat adiabatically when they compress as they lose altitude. These winds should then remove H2O moisture from the uppermost layer of the sand dunes that are directly in their path. Two likely locations where this desiccation may occur preferentially is at the termination of Chasma Boreale and the ice cap at Olympia Undae. We will search for this effect by sharpening the spatial structure of the epithermal neutron counting rates measured at northern high latitudes using the Mars Odyssey Neutron Spectrometer (MONS). The epithermal range of neutron energies is nearly uniquely sensitive to the hydrogen content of surface soils, which should likely be in the form of H2O/OH molecules/radicals. We therefore convert epithermal counting rates in terms of Water-Equivalent-Hydrogen, WEH. However, MONS counting-rate data have a FWHM of ~550 km., which is sufficiently broad to prevent a close association of WEH variability with images of geological features. In this study, we reduce spurious features in the instrument smeared neutron counting rates through deconvolution. We choose the PIXON numerical deconvolution technique for this purpose. This technique uses a statistical approach (Pina 2001, Eke 2001), which is capable of removing spurious features in the data in the presence of noise. We have previously carried out a detailed

  5. Isolation and characterization of coliforms from glacial ice and water in Canada's High Arctic.

    Science.gov (United States)

    Dancer, S J; Shears, P; Platt, D J

    1997-05-01

    Ellesmere Island is the northern most member of the Canadian Arctic Archipelago with over one-third of the land mass covered by ice. A joint services expedition to the island's Blue Mountains offered a unique opportunity for microbiological studies of resident bacteria in an environment uninhabited by man. Over 100 samples of water and ice were collected from stream, lake and glacier and the filtrate cultured under canvas. Bacterial growth was harvested onto swabs for transport back to the UK and 50 coliforms chosen at random for identification and antibiotic susceptibility testing. Most of the glacial strains were capsulated, pigmented and some over 2000 years old. Genera such as Serratia, Enterobacter, Klebsiella and Yersinia were found; speciation was inconclusive and some organisms remain unidentified. Ampicillin resistance was evident in 80% of water isolates as opposed to 30% of the glacial organisms, but the isolates were generally exquisitely susceptible to antibiotics. The facility for ampicillin resistance did not appear to be transferable. Plasmid DNA was found in 33% of the glacial organisms and over 50% of the water isolates. Similar profiles were identified within and apparently between species and required plasmid restriction analysis to help establish identity. Plasmid-free Serratia spp. were subjected to genomic fingerprinting. Indistinguishable patterns were found within sets of isolates both widely spaced by distance and collection date and it was postulated that coliforms able to survive an Arctic environment had spread extensively throughout the expedition area. In conclusion, this study contributes towards knowledge of naturally occurring antibiotic resistance, confirms the presence of plasmids and genotypic data provided evidence that potentially ancient organisms from glaciers can be cultured from water samples significantly distant.

  6. Heavy water production by alkaline water electrolysis

    International Nuclear Information System (INIS)

    Kamath, Sachin; Sandeep, K.C.; Bhanja, Kalyan; Mohan, Sadhana; Sugilal, G.

    2014-01-01

    Several heavy water isotope production processes are reported in literature. Water electrolysis in combination with catalytic exchange CECE process is considered as a futuristic process to increase the throughput and reduce the cryogenic distillation load but the application is limited due to the high cost of electricity. Any improvement in the efficiency of electrolyzers would make this process more attractive. The efficiency of alkaline water electrolysis is governed by various phenomena such as activation polarization, ohmic polarization and concentration polarization in the cell. A systematic study on the effect of these factors can lead to methods for improving the efficiency of the electrolyzer. A bipolar and compact type arrangement of the alkaline water electrolyzer leads to increased efficiency and reduced inventory in comparison to uni-polar tank type electrolyzers. The bipolar type arrangement is formed when a number of single cells are stacked together. Although a few experimental studies have been reported in the open literature, CFD simulation of a bipolar compact alkaline water electrolyzer with porous electrodes is not readily available.The principal aim of this study is to simulate the characteristics of a single cell compact electrolyzer unit. The simulation can be used to predict the Voltage-Current Density (V-I) characteristics, which is a measure of the efficiency of the process.The model equations were solved using COMSOL multi-physics software. The simulated V-I characteristic is compared with the experimental data

  7. The Calculated and Measured Performance Characteristics of a Heated-Wire Liquid-Water-Content Meter for Measuring Icing Severity

    Science.gov (United States)

    Neel, Carr B.; Steinmetz, Charles P.

    1952-01-01

    Ground tests have been made of an instrument which, when assembled in a more compact form for flight installation, could be used to obtain statistical flight data on the liquid-water content of icing clouds and to provide an indication of icing severity. The sensing element of the instrument consists of an electrically heated wire which is mounted in the air stream. The degree of cooling of the wire resulting from evaporation of the impinging water droplets is a measure. of the liquid-water content of the cloud. Determination of the value of the liquid-water content from the wire temperature at any instant requires a knowledge of the airspeed, altitude, and air temperature. An analysis was made of the temperature response of a heated wire exposed to an air stream containing water drops. Comparisons were made of the liquid-water content as measured with several heated wires and absorbent cylinders in an artificially produced cloud. For one of the wires, comparative tests were made with a rotating-disk icing-rate meter in an icing wind tunnel. From the test results, it was shown that an instrument for measuring the concentration of liquid water in an air stream can be built using an electrically heated wire of known temperatureresistance characteristics, and that the performance of such a device can be predicted using appropriate theory. Although an instrument in a form suitable for gathering statistical data in flight was not built, the practicability of constructing such an instrument was illustrated. The ground-test results indicated that a flight heated-wire instrument would be simple and durable, would respond rapidly to variations in liquid-water content, and could be used for the measurement of water content in clouds which are above freezing temperature, as well as in icing clouds.

  8. Lattice Boltzmann Simulation of Water Isotope Fractionation During Growth of Ice Crystals in Clouds

    Science.gov (United States)

    Lu, G.; Depaolo, D.; Kang, Q.; Zhang, D.

    2006-12-01

    The isotopic composition of precipitation, especially that of snow, plays a special role in the global hydrological cycle and in reconstruction of past climates using polar ice cores. The fractionation of the major water isotope species (HHO, HDO, HHO-18) during ice crystal formation is critical to understanding the global distribution of isotopes in precipitation. Ice crystal growth in clouds is traditionally treated with a spherically- symmetric steady state diffusion model, with semi-empirical modifications added to account for ventilation and for complex crystal morphology. Although it is known that crystal growth rate, which depends largely on the degree of vapor over-saturation, determines crystal morphology, there are no existing quantitative models that directly relate morphology to the vapor saturation factor. Since kinetic (vapor phase diffusion-controlled) isotopic fractionation also depends on growth rate, there should be a direct relationship between vapor saturation, crystal morphology, and crystal isotopic composition. We use a 2D Lattice-Boltzmann model to simulate diffusion-controlled ice crystal growth from vapor- oversaturated air. In the model, crystals grow solely according to the diffusive fluxes just above the crystal surfaces, and hence crystal morphology arises from the initial and boundary conditions in the model and does not need to be specified a priori. The input parameters needed are the isotope-dependent vapor deposition rate constant (k) and the water vapor diffusivity in air (D). The values of both k and D can be computed from kinetic theory, and there are also experimentally determined values of D. The deduced values of k are uncertain to the extent that the sticking coefficient (or accommodation coefficient) for ice is uncertain. The ratio D/k is a length that determines the minimum scale of dendritic growth features and allows us to scale the numerical calculations to atmospheric conditions using a dimensionless Damkohler number

  9. Effectiveness of a chemical herder in association with in-situ burning of oil spills in ice-infested water

    DEFF Research Database (Denmark)

    van Gelderen, Laurens; Fritt-Rasmussen, Janne; Jomaas, Grunde

    2017-01-01

    The average herded slick thickness, surface distribution and burning efficiency of a light crude oil were studied in ice-infested water to determine the effectiveness of a chemical herder in facilitating the in-situ burning of oil. Experiments were performed in a small scale (1.0m2) and an interm......The average herded slick thickness, surface distribution and burning efficiency of a light crude oil were studied in ice-infested water to determine the effectiveness of a chemical herder in facilitating the in-situ burning of oil. Experiments were performed in a small scale (1.0m2...

  10. Ice-nucleation negative fluorescent pseudomonads isolated from Hebridean cloud and rain water produce biosurfactants

    Science.gov (United States)

    Ahern, H. E.; Walsh, K. A.; Hill, T. C. J.; Moffett, B. F.

    2006-10-01

    Microorganisms were discovered in clouds over 100 years ago but information on bacterial community structure and function is limited. Clouds may not only be a niche within which bacteria could thrive but they might also influence dynamic processes using ice nucleating and cloud condensing abilities. Cloud and rain samples were collected from two mountains in the Outer Hebrides, NW Scotland, UK. Community composition was determined using a combination of amplified 16S ribosomal DNA restriction analysis and sequencing. 256 clones yielded 100 operational taxonomic units (OTUs) of which half were related to bacteria from terrestrial psychrophilic environments. Cloud samples were dominated by a mixture of fluorescent Pseudomonas spp., some of which have been reported to be ice nucleators. It was therefore possible that these bacteria were using the ice nucleation (IN) gene to trigger the Bergeron-Findeisen process of raindrop formation as a mechanism for dispersal. In this study the IN gene was not detected in any of the isolates using both polymerase chain reaction (PCR) and differential scanning calorimetry (DSC). Instead 55% of the total isolates from both cloud and rain samples displayed significant biosurfactant activity when analyzed using the drop-collapse technique. All were characterised as fluorescent pseudomonads. Surfactants have been found to be very important in lowering atmospheric critical supersaturations required for the activation of aerosols into cloud condensation nuclei (CCN). It is also known that surfactants influence cloud droplet size and increase cloud lifetime and albedo. Some bacteria are known to act as CCN and so it is conceivable that these fluorescent pseudomonads are using surfactants to facilitate their activation from aerosols into CCN. This would allow water scavenging, countering desiccation, and assist in their widespread dispersal.

  11. The potential influence of Asian and African mineral dust on ice, mixed-phase and liquid water clouds

    Directory of Open Access Journals (Sweden)

    A. Wiacek

    2010-09-01

    Full Text Available This modelling study explores the availability of mineral dust particles as ice nuclei for interactions with ice, mixed-phase and liquid water clouds, also tracking the particles' history of cloud-processing. We performed 61 320 one-week forward trajectory calculations originating near the surface of major dust emitting regions in Africa and Asia using high-resolution meteorological analysis fields for the year 2007. Dust-bearing trajectories were assumed to be those coinciding with known dust emission seasons, without explicitly modelling dust emission and deposition processes. We found that dust emissions from Asian deserts lead to a higher potential for interactions with high ice clouds, despite being the climatologically much smaller dust emission source. This is due to Asian regions experiencing significantly more ascent than African regions, with strongest ascent in the Asian Taklimakan desert at ~25%, ~40% and 10% of trajectories ascending to 300 hPa in spring, summer and fall, respectively. The specific humidity at each trajectory's starting point was transported in a Lagrangian manner and relative humidities with respect to water and ice were calculated in 6-h steps downstream, allowing us to estimate the formation of liquid, mixed-phase and ice clouds. Downstream of the investigated dust sources, practically none of the simulated air parcels reached conditions of homogeneous ice nucleation (T≲−40 °C along trajectories that have not experienced water saturation first. By far the largest fraction of cloud forming trajectories entered conditions of mixed-phase clouds, where mineral dust will potentially exert the biggest influence. The majority of trajectories also passed through atmospheric regions supersaturated with respect to ice but subsaturated with respect to water, where so-called "warm ice clouds" (T≳−40 °C theoretically may form prior to supercooled water or mixed-phase clouds. The importance of "warm ice

  12. Significance analysis of the regional differences on icing time of water onto fire protective clothing

    Science.gov (United States)

    Zhao, L. Z.; Jing, L. S.; Zhang, X. Z.; Xia, J. J.; Chen, Y.; Chen, T.; Hu, C.; Bao, Z. M.; Fu, X. C.; Wang, R. J.; Wang, Y.; Wang, Y. J.

    2017-09-01

    The object of this work was to determine the icing temperature in icing experiment. Firstly, a questionnaire investigation was carried out on 38 fire detachments in different regions. These Statistical percentage results were divided into northern east group and northern west group. Secondly, a significance analysis between these two results was made using Mann-Whitney U test. Then the icing temperature was determined in different regions. Thirdly, the icing experiment was made in the environment of -20°C in Daxing’an Mountain. The anti-icing effect of new fire protective clothing was verified in this icing.

  13. Evaporation Rates for Liquid Water and Ice Under Current Martian Conditions

    Science.gov (United States)

    Sears, D. W. G.; Moore, S. R.; Meier, A.; Chittenden, J.; Kareev, M.; Farmer, C. B.

    2004-01-01

    A number of studies have been concerned with the evaporation rates under martian conditions in order to place limits on the possible survival time of both liquid water and ice exposed on the surface of Mars. Such studies also aid in assessing the efficacy of an overlying layer of dust or loose regolith material in providing a barrier to free evaporation and thus prolong the lifetime of water in locations where its availability to putative living organisms would be significant. A better quantitative understanding of the effects of phase changes of water in the near surface environment would also aid the evaluation of the possible role of water in the formation of currently observed features, such as gullies in cliff walls and relatively short-term changes in the albedo of small surface areas ('dark stains'). Laboratory measurements aimed at refinement of our knowledge of these values are described here. The establishment of accurate values for evaporation rates and their dependence on the physical conditions of temperature, pressure and energy input, is an important benchmark for the further investigation of the efficacy of barriers to free evaporation in providing a prolonged period of survival of the water, particularly as a liquid.

  14. An Assessment of the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

    Science.gov (United States)

    Steen, Laura E.; Ide, Robert F.; Van Zante, Judith F.

    2015-01-01

    The NASA Glenn Icing Research tunnel has been using an Icing Blade technique to measure cloud liquid water content (LWC) since 1980. The IRT conducted tests with SEA Multi-Element sensors from 2009 to 2011 to assess their performance in measuring LWC. These tests revealed that the Multi-Element sensors showed some significant advantages over the Icing Blade, particularly at higher water contents, higher impingement rates, and large drop sizes. Results of these and other tests are presented here.

  15. Assessment of electrical stunning in fresh water of African Catfish (Clarias gariepinus) and chilling in ice water for loss of consciousness and sensibility

    NARCIS (Netherlands)

    Lambooij, E.; Kloosterboer, R.J.; Gerritzen, M.A.; Vis, van de J.W.

    2006-01-01

    The overall objective of the study was to evaluate loss of consciousness and sensibility after electrical stunning in fresh water and live chilling in ice water for slaughter of African catfish using measurement of electrical brain and heart activity. To provoke immediate loss of consciousness and

  16. A new technique for the remediation of oil spills from ice infested waters

    International Nuclear Information System (INIS)

    Mustafiz, S.; Bjorndalen, N.; Basu, A.; Islam, M.R.; Lee, K.

    2003-01-01

    The petroleum industry is concerned about remediating oil spills in an environmentally sound manner, particularly when oil has to be removed from ice-infested waters where traditional remediation methods are ineffectual due to frigid temperatures. The authors propose using fish scale powder as an environmentally friendly and economically viable remediation medium for oil spills on ice. Tests have been conducted and results were compared to results obtained using bentonite, the conventional remediation medium. Fish-scale was found to absorb the oil spill and form fine emulsions that can readily biodegrade. The oil-fish scale media can also be re-used for other applications, such as drilling mud. The soaking time was much faster using fish scale than bentonite (less than 3 minutes for all weights of fish scale studied). Fish scale powder is an inexpensive material widely available in coastal regions. It was concluded that fish scale could be an alternate remediation medium which could yield great savings in oil spill clean up operations. 25 refs., 10 figs

  17. A COMPREHENSIVE STUDY OF HYDROGEN ADSORBING TO AMORPHOUS WATER ICE: DEFINING ADSORPTION IN CLASSICAL MOLECULAR DYNAMICS

    Energy Technology Data Exchange (ETDEWEB)

    Dupuy, John L.; Lewis, Steven P.; Stancil, P. C. [Department of Physics and Astronomy and the Center for Simulational Physics, University of Georgia, Athens, GA 30602 (United States)

    2016-11-01

    Gas–grain and gas–phase reactions dominate the formation of molecules in the interstellar medium (ISM). Gas–grain reactions require a substrate (e.g., a dust or ice grain) on which the reaction is able to occur. The formation of molecular hydrogen (H{sub 2}) in the ISM is the prototypical example of a gas–grain reaction. In these reactions, an atom of hydrogen will strike a surface, stick to it, and diffuse across it. When it encounters another adsorbed hydrogen atom, the two can react to form molecular hydrogen and then be ejected from the surface by the energy released in the reaction. We perform in-depth classical molecular dynamics simulations of hydrogen atoms interacting with an amorphous water-ice surface. This study focuses on the first step in the formation process; the sticking of the hydrogen atom to the substrate. We find that careful attention must be paid in dealing with the ambiguities in defining a sticking event. The technical definition of a sticking event will affect the computed sticking probabilities and coefficients. Here, using our new definition of a sticking event, we report sticking probabilities and sticking coefficients for nine different incident kinetic energies of hydrogen atoms [5–400 K] across seven different temperatures of dust grains [10–70 K]. We find that probabilities and coefficients vary both as a function of grain temperature and incident kinetic energy over the range of 0.99–0.22.

  18. Surface studies of water isotopes in Antarctica for quantitative interpretation of deep ice core data

    Science.gov (United States)

    Landais, Amaelle; Casado, Mathieu; Prié, Frédéric; Magand, Olivier; Arnaud, Laurent; Ekaykin, Alexey; Petit, Jean-Robert; Picard, Ghislain; Fily, Michel; Minster, Bénédicte; Touzeau, Alexandra; Goursaud, Sentia; Masson-Delmotte, Valérie; Jouzel, Jean; Orsi, Anaïs

    2017-07-01

    Polar ice cores are unique climate archives. Indeed, most of them have a continuous stratigraphy and present high temporal resolution of many climate variables in a single archive. While water isotopic records (δD or δ18O) in ice cores are often taken as references for past atmospheric temperature variations, their relationship to temperature is associated with a large uncertainty. Several reasons are invoked to explain the limitation of such an approach; in particular, post-deposition effects are important in East Antarctica because of the low accumulation rates. The strong influence of post-deposition processes highlights the need for surface polar research programs in addition to deep drilling programs. We present here new results on water isotopes from several recent surface programs, mostly over East Antarctica. Together with previously published data, the new data presented in this study have several implications for the climatic reconstructions based on ice core isotopic data: (1) The spatial relationship between surface mean temperature and mean snow isotopic composition over the first meters in depth can be explained quite straightforwardly using simple isotopic models tuned to d-excess vs. δ18O evolution in transects on the East Antarctic sector. The observed spatial slopes are significantly higher (∼ 0.7-0.8‰·°C-1 for δ18O vs. temperature) than seasonal slopes inferred from precipitation data at Vostok and Dome C (0.35 to 0.46‰·°C-1). We explain these differences by changes in condensation versus surface temperature between summer and winter in the central East Antarctic plateau, where the inversion layer vanishes in summer. (2) Post-deposition effects linked to exchanges between the snow surface and the atmospheric water vapor lead to an evolution of δ18O in the surface snow, even in the absence of any precipitation event. This evolution preserves the positive correlation between the δ18O of snow and surface temperature, but is

  19. Monitoring and Quantifying Subsurface Ice and Water Content in Permafrost Regions Based on Geophysical Data Sets

    Science.gov (United States)

    Hauck, C.; Bach, M.; Hilbich, C.

    2007-12-01

    Based on recent observational evidence of climate change in permafrost regions, it is now recognised that a detailed knowledge of the material composition of the subsurface in permafrost regions is required for modelling of the future evolution of the ground thermal regime and an assessment of the hazard potential due to degrading permafrost. However, due to the remote location of permafrost areas and the corresponding difficulties in obtaining high-quality data sets of the subsurface, knowledge about the material composition in permafrost areas is scarce. In frozen ground subsurface material may consist of four different phases: rock/soil matrix, unfrozen pore water, ice and air-filled pore space. Applications of geophysical techniques for determining the subsurface composition are comparatively cheap and logistically feasible alternatives to the single point information from boreholes. Due to the complexity of the subsurface a combination of complementary geophysical methods (e.g. electrical resistivity tomography (ERT) and refraction seismic tomography) is often favoured to avoid ambiguities in the interpretation of the results. The indirect nature of geophysical soundings requires a relation between the measured variable (electrical resistivity, seismic velocity) and the rock-, water-, ice- and air content. In this contribution we will present a model which determines the volumetric fractions of these four phases from tomographic electrical and seismic data sets. The so-called 4-phase model is based on two well-known geophysical mixing rules using observed resistivity and velocity data as input data on a 2-dimensional grid. Material properties such as resistivity and P- wave velocity of the host rock material and the pore water have to be known beforehand. The remaining free model parameters can be determined by a Monte-Carlo approach, the results of which are used additionally as indicator for the reliability of the model results. First results confirm the

  20. Pain during ice water test distinguishes clinical bladder hypersensitivity from overactivity disorders

    Directory of Open Access Journals (Sweden)

    Bountra Chas

    2006-12-01

    Full Text Available Abstract Background The Bladder cooling reflex (BCR i.e. uninhibited detrusor contractions evoked by intravesical instillation of cold saline, is a segmental reflex believed to be triggered by menthol sensitive cold receptors in the bladder wall, with the afferent signals transmitted by C fibres. The BCR is a neonatal reflex that becomes suppressed by descending signals from higher centres at approximately the time when the child gains full voluntary control of voiding. It re-emerges in adults with neurogenic detrusor overactivity as a consequence of loss of central descending inhibition, resulting from conditions such as spinal cord injury or multiple sclerosis. We have recently shown an increase of nerve fibres expressing the cool and menthol receptor TRPM8 in both overactive (IDO and painful bladder syndrome (PBS, but its functional significance is unknown. We have therefore studied the bladder cooling reflex and associated sensory symptoms in patients with PBS and overactivity disorders. Methods The BCR, elicited by ice water test (IWT was performed in patients with painful bladder syndrome (PBS, n = 17, idiopathic detrusor overactivity (IDO, n = 22, neurogenic detrusor overactivity (NDO, n = 4 and stress urinary incontinence (as controls, n = 21. The IWT was performed by intravesical instillation of cold saline (0 – 4°C. A positive IWT was defined as presence of uninhibited detrusor contraction evoked by cold saline, associated with urgency or with fluid expulsion. Patients were asked to report and rate any pain and cold sensation during the test. Results A positive IWT was observed in IDO (6/22, 27.3% and NDO (4/4, 100% patients, but was negative in all control and PBS patients. Thirteen (76.5% PBS patients reported pain during the IWT, with significantly higher pain scores during ice water instillation compared to the baseline (P = 0.0002, or equivalent amount of bladder filling (100 mls with saline at room temperature (P = 0.015. None

  1. Assessing modelled spatial distributions of ice water path using satellite data

    Science.gov (United States)

    Eliasson, S.; Buehler, S. A.; Milz, M.; Eriksson, P.; John, V. O.

    2010-05-01

    The climate models used in the IPCC AR4 show large differences in monthly mean cloud ice. The most valuable source of information that can be used to potentially constrain the models is global satellite data. For this, the data sets must be long enough to capture the inter-annual variability of Ice Water Path (IWP). PATMOS-x was used together with ISCCP for the annual cycle evaluation in Fig. 7 while ECHAM-5 was used for the correlation with other models in Table 3. A clear distinction between ice categories in satellite retrievals, as desired from a model point of view, is currently impossible. However, long-term satellite data sets may still be used to indicate the climatology of IWP spatial distribution. We evaluated satellite data sets from CloudSat, PATMOS-x, ISCCP, MODIS and MSPPS in terms of monthly mean IWP, to determine which data sets can be used to evaluate the climate models. IWP data from CloudSat cloud profiling radar provides the most advanced data set on clouds. As CloudSat data are too short to evaluate the model data directly, it was mainly used here to evaluate IWP from the other satellite data sets. ISCCP and MSPPS were shown to have comparatively low IWP values. ISCCP shows particularly low values in the tropics, while MSPPS has particularly low values outside the tropics. MODIS and PATMOS-x were in closest agreement with CloudSat in terms of magnitude and spatial distribution, with MODIS being the best of the two. As PATMOS-x extends over more than 25 years and is in fairly close agreement with CloudSat, it was chosen as the reference data set for the model evaluation. In general there are large discrepancies between the individual climate models, and all of the models show problems in reproducing the observed spatial distribution of cloud-ice. Comparisons consistently showed that ECHAM-5 is the GCM from IPCC AR4 closest to satellite observations.

  2. ALES+: Adapting a homogenous ocean retracker for satellite altimetry to sea ice leads, coastal and inland waters

    DEFF Research Database (Denmark)

    Passaro, Marcello; Kildegaard Rose, Stine; Andersen, Ole B.

    2018-01-01

    ice retracker used for fitting specular echoes. Compared to an existing open ocean altimetry dataset, the presented strategy increases the number of sea level retrievals in the sea ice-covered area and the correlation with a local tide gauge. Further tests against in-situ data show that also......Water level from sea ice-covered oceans is particularly challenging to retrieve with satellite radar altimeters due to the different shapes assumed by the returned signal compared with the standard open ocean waveforms. Valid measurements are scarce in large areas of the Arctic and Antarctic Oceans...... the fitting of the signal depending on the sea state and on the slope of its trailing edge. The algorithm modifies the existing Adaptive Leading Edge Subwaveform retracker originally designed for coastal waters, and is applied to Envisat and ERS-2 missions. The validation in a test area of the Arctic Ocean...

  3. Less ice on the Baltic reduces the extent of hypoxic bottom waters and sedimentary phosphorus release

    NARCIS (Netherlands)

    Vermaat, J.E.; Bouwer, L.M.

    2009-01-01

    A significant relation was established between the maximum extent of sea ice covering the Baltic Sea and the hypoxic area in the deeper parts of the Baltic Proper, with a lag of 2 years: for the period 1970-2000, less ice was correlated with a smaller anoxic area. At the same time, maximum ice

  4. Prebiotic water/ice as medium for peptide catlysis and RNA world

    DEFF Research Database (Denmark)

    Wieczorek, Rafal

    The emergence of RNA chains from prebiotic soup is considered a stumbling block in the RNA world theory (Orgel 2004). Both the activation of RNA monomers and their subsequent oligomerization is hard to achieve in accepted early Earth conditions, thus putting doubt on the prebiotic plausibility....... As an environment medium we have used water/ice eutectic phase – conditions believed to be present on the early Earth and many icy moons. In this work we describe a prebiotically plausible system in which L-dipeptides containing a histidine residue, primarily the SerHis dipeptide act as catalyst for the formation...... able to succesfully demonstratate formation of short oligomers of RNA. During the oligomerization, an active intermediate (dipeptide-mononucleotide) is produced, which is the reactive species. Details of the mechanism and kinetics, which could be elucidated with a set of control experiments, further...

  5. Illumination Conditions at the Asteroid 4 Vesta: Implications for the Presence of Water Ice

    Science.gov (United States)

    Stubbs, Timothy J.; Wang, Yongli

    2011-01-01

    The mean illumination conditions and surface temperatures over one orbital period are calculated for the Asteroid 4 Vesta using a coarse digital elevation model produced from Hubble Space Telescope images. Even with the anticipated effects of finer-scale topography taken into account, it is unlikely that any significant permanently shadowed regions currently exist on Vesta due to its large axial tilt (approx. = 27deg). However, under present day conditions, it is predicted that about half of Vesta's surface has an average temperature of less than 145 K, which, based on previous thermal modeling of main belt asteroids, suggests that water ice could survive in the top few meters of the vestal regolith on billion-year timescales.

  6. Extratropical Weather Systems on Mars: Radiatively-Active Water Ice Effects

    Science.gov (United States)

    Hollingsworth, J. L.; Kahre, M. A.; Haberle, R. M.; Urata, R. A.; Montmessin, F.

    2017-01-01

    Extratropical, large-scale weather disturbances, namely transient, synoptic-period,baroclinic barotropic eddies - or - low- (high-) pressure cyclones (anticyclones), are components fundamental to global circulation patterns for rapidly rotating, differentially heated, shallow atmospheres such as Earth and Mars. Such "wave-like" disturbances that arise via (geophysical) fluid shear instability develop, mature and decay, and travel west-to-east in the middle and high latitudes within terrestrial-like planetary atmospheres. These disturbances serve as critical agents in the transport of heat and momentum between low and high latitudes of the planet. Moreover, they transport trace species within the atmosphere (e.g., water vapor/ice, other aerosols (dust), chemical species, etc). Between early autumn through early spring, middle and high latitudes on Mars exhibit strong equator-to-pole mean temperature contrasts (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that such strong baroclinicity supports vigorous, large-scale eastward traveling weather systems [Banfield et al., 2004; Barnes et al., 1993]. A good example of traveling weather systems, frontal wave activity and sequestered dust activity from MGS/MOC image analyses is provided in Figure 1 (cf. Wang et al. [2005]). Utilizing an upgraded and evolving version of the NASA Ames Research Center (ARC) Mars global climate model, investigated here are key dynamical and physical aspects of simulated northern hemisphere (NH) large-scale extratropica lweather systems,with and without radiatively-active water ice clouds. Mars Climate Model:

  7. A prototype method for diagnosing high ice water content probability using satellite imager data

    Science.gov (United States)

    Yost, Christopher R.; Bedka, Kristopher M.; Minnis, Patrick; Nguyen, Louis; Strapp, J. Walter; Palikonda, Rabindra; Khlopenkov, Konstantin; Spangenberg, Douglas; Smith, William L., Jr.; Protat, Alain; Delanoe, Julien

    2018-03-01

    Recent studies have found that ingestion of high mass concentrations of ice particles in regions of deep convective storms, with radar reflectivity considered safe for aircraft penetration, can adversely impact aircraft engine performance. Previous aviation industry studies have used the term high ice water content (HIWC) to define such conditions. Three airborne field campaigns were conducted in 2014 and 2015 to better understand how HIWC is distributed in deep convection, both as a function of altitude and proximity to convective updraft regions, and to facilitate development of new methods for detecting HIWC conditions, in addition to many other research and regulatory goals. This paper describes a prototype method for detecting HIWC conditions using geostationary (GEO) satellite imager data coupled with in situ total water content (TWC) observations collected during the flight campaigns. Three satellite-derived parameters were determined to be most useful for determining HIWC probability: (1) the horizontal proximity of the aircraft to the nearest overshooting convective updraft or textured anvil cloud, (2) tropopause-relative infrared brightness temperature, and (3) daytime-only cloud optical depth. Statistical fits between collocated TWC and GEO satellite parameters were used to determine the membership functions for the fuzzy logic derivation of HIWC probability. The products were demonstrated using data from several campaign flights and validated using a subset of the satellite-aircraft collocation database. The daytime HIWC probability was found to agree quite well with TWC time trends and identified extreme TWC events with high probability. Discrimination of HIWC was more challenging at night with IR-only information. The products show the greatest capability for discriminating TWC ≥ 0.5 g m-3. Product validation remains challenging due to vertical TWC uncertainties and the typically coarse spatio-temporal resolution of the GEO data.

  8. Sea Ice Ecosystems

    Science.gov (United States)

    Arrigo, Kevin R.

    2014-01-01

    Polar sea ice is one of the largest ecosystems on Earth. The liquid brine fraction of the ice matrix is home to a diverse array of organisms, ranging from tiny archaea to larger fish and invertebrates. These organisms can tolerate high brine salinity and low temperature but do best when conditions are milder. Thriving ice algal communities, generally dominated by diatoms, live at the ice/water interface and in recently flooded surface and interior layers, especially during spring, when temperatures begin to rise. Although protists dominate the sea ice biomass, heterotrophic bacteria are also abundant. The sea ice ecosystem provides food for a host of animals, with crustaceans being the most conspicuous. Uneaten organic matter from the ice sinks through the water column and feeds benthic ecosystems. As sea ice extent declines, ice algae likely contribute a shrinking fraction of the total amount of organic matter produced in polar waters.

  9. Wave excited motion of a body floating on water confined between two semi-infinite ice sheets

    Science.gov (United States)

    Ren, K.; Wu, G. X.; Thomas, G. A.

    2016-12-01

    The wave excited motion of a body floating on water confined between two semi-infinite ice sheets is investigated. The ice sheet is treated as an elastic thin plate and water is treated as an ideal and incompressible fluid. The linearized velocity potential theory is adopted in the frequency domain and problems are solved by the method of matched eigenfunctions expansion. The fluid domain is divided into sub-regions and in each sub-region the velocity potential is expanded into a series of eigenfunctions satisfying the governing equation and the boundary conditions on horizontal planes including the free surface and ice sheets. Matching is conducted at the interfaces of two neighbouring regions to ensure the continuity of the pressure and velocity, and the unknown coefficients in the expressions are obtained as a result. The behaviour of the added mass and damping coefficients of the floating body with the effect of the ice sheets and the excitation force are analysed. They are found to vary oscillatorily with the wave number, which is different from that for a floating body in the open sea. The motion of the body confined between ice sheets is investigated, in particular its resonant behaviour with extremely large motion found to be possible under certain conditions. Standing waves within the polynya are also observed.

  10. Temperature distribution of a water droplet moving on a heated super-hydrophobic surface under the icing condition

    Science.gov (United States)

    Yamazaki, Masafumi; Sumino, Yutaka; Morita, Katsuaki

    2017-11-01

    In the aviation industry, ice accretion on the airfoil has been a hazardous issue since it greatly declines the aerodynamic performance. Electric heaters and bleed air, which utilizes a part of gas emissions from engines, are used to prevent the icing. Nowadays, a new de-icing system combining electric heaters and super hydrophobic coatings have been developed to reduce the energy consumption. In the system, the heating temperature and the coating area need to be adjusted. Otherwise, the heater excessively consumes energy when it is set too high and when the coating area is not properly located, water droplets which are once dissolved possibly adhere again to the rear part of the airfoil as runback ice In order to deal with these problems, the physical phenomena of water droplets on the hydrophobic surface demand to be figured out. However, not many investigations focused on the behavior of droplets under the icing condition have been conducted. In this research, the temperature profiling of the rolling droplet on a heated super-hydrophobic surface is experimentally observed by the dual luminescent imaging.

  11. Improving the gas productivity of the alkaline electrolyzer through the circulation technique

    Directory of Open Access Journals (Sweden)

    Kitipong Tangphant

    2014-03-01

    Full Text Available This research aims to study and improve the efficiency of a KOH electrolyzer through the gas productivity of the electrolyzer with different the circulation technique. In this work, the conceptual design of an electrolyzer falls into 2 categories; without pumping and with pumping. Direct current electricity at 5 different levels of 10, 15, 20, 25 and 30 A are charged into the system and the gas flow rate generated from the electrolyzer is subsequently monitored. The results show that at 30 A the gas generated from the circulation with pumping and the circulation without pumping are 2.31 litre/min and 1.76 litre/min, respectively. It is also found that the energy consumed by both techniques is the same; however, the circulation with pumping design shows the better gas productivity than that of the circulation without pumping design.

  12. Original deep convection in the atmosphere of Mars driven by the radiative impact of dust and water-ice particles

    Science.gov (United States)

    Spiga, A.; Madeleine, J. B.; Hinson, D.; Millour, E.; Forget, F.; Navarro, T.; Määttänen, A.; Montmessin, F.

    2017-09-01

    We unveil two examples of deep convection on Mars - in dust storms and water-ice clouds - to demonstrate that the radiative effect of aerosols and clouds can lead to powerful convective motions just as much as the release of latent heat in moist convection

  13. Near-Surface Profiles of Water Stable Isotope Components and Indicated Transitional History of Ice-Wedge Polygons Near Barrow

    Science.gov (United States)

    Iwahana, G.; Wilson, C.; Newman, B. D.; Heikoop, J. M.; Busey, R.

    2017-12-01

    Wetlands associated with ice-wedge polygons are commonly distributed across the Arctic Coastal Plain of northern Alaska, a region underlain by continuous permafrost. Micro-topography of the ice-wedge polygons controls local hydrology, and the micro-topography could be altered due to factors such like surface vegetation, wetness, freeze-thaw cycles, and permafrost degradation/aggradation under climate change. Understanding status of the wetlands in the near future is important because it determines biogeochemical cycle, which drives release of greenhouse gases from the ground. However, transitional regime of the ice-wedge polygons under the changing climate is not fully understood. In this study, we analyzed geochemistry of water extracted from frozen soil cores sampled down to about 1m depth in 2014 March at NGEE-Arctic sites in the Barrow Environmental Observatory. The cores were sampled from troughs/rims/centers of five different low-centered or flat-centered polygons. The frozen cores are divided into 5-10cm cores for each location, thawed in sealed plastic bags, and then extracted water was stored in vials. Comparison between the profiles of geochemistry indicated connection of soil water in the active layer at different location in a polygon, while it revealed that distinctly different water has been stored in permafrost layer at troughs/rims/centers of some polygons. Profiles of volumetric water content (VWC) showed clear signals of freeze-up desiccation in the middle of saturated active layers as low VWC anomalies at most sampling points. Water in the active layer and near-surface permafrost was classified into four categories: ice wedge / fresh meteoric / transitional / highly fractionated water. The overall results suggested prolonged separation of water in the active layer at the center of low-centered polygons without lateral connection in water path in the past.

  14. Summary of Market Opportunities for Electric Vehicles and Dispatchable Load in Electrolyzers

    Energy Technology Data Exchange (ETDEWEB)

    Denholm, Paul [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Eichman, Joshua [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Markel, Tony [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ma, Ookie [U.S Department of Energy, Washington, DC (United States)

    2015-05-19

    Electric vehicles (EVs) and electrolyzers are potentially significant sources of new electric loads. Both are flexible in that the amount of electricity consumed can be varied in response to a variety of factors including the cost of electricity. Because both EVs and electrolyzers can control the timing of electricity purchases, they can minimize energy costs by timing the purchases of energy to periods of lowest costs.

  15. Dazzled by ice and snow: improving medium ocean color images in Arctic waters

    Science.gov (United States)

    Babin, M.; Goyens, C.; Belanger, S.

    2016-02-01

    The importance of phytoplankton blooms for the Arctic marine ecosystem is well recognized but studies disagree as the consequences of sea ice melt on the phytoplankton distribution and growth. This limited understanding in actual and future Arctic phytoplankton dynamics mostly results from a lack of accurate data at the receding ice-edges where phytoplankton blooms are known to occur. Ocean color sensors on-board satellites represent therefore a crucial tool providing a synoptic view of the ocean systems over broad spatio-temporal scales. However, today the use of ocean color data in Arctic environments remains strongly compromised due to, among others, sea ice contamination. Indeed, medium ocean color data along the receding ice edge are "dazzled" by nearby and/or sub-pixel highly reflective ice floes. Standard ocean color data methods ignore ice-contamination during data processing which deteriorates the quality of the radiometric data and subsequent satellite derived bio-geochemical products. Moreover, since Arctic phytoplankton spring blooms typically develop along the receding ice-edges, ignoring ice-contaminated pixels may lead to wrong interpretation of satellite data. The present study shows how adjacent and sub-pixel sea-ice floes affect the retrieved ocean color data. A correction approach is also suggested to improve the "dazzled" ocean color pixels along the receding ice edge in the aim to provide additional support to better understand current and future trends in phytoplankton dynamics.

  16. Differences in plankton community structure and carbon cycling along a climate gradient from the Greenland Ice Sheet to offshore waters

    DEFF Research Database (Denmark)

    Arendt, K.E.; Nielsen, Torkel Gissel; Rysgaard, S.

    Huge differences in plankton community structures and biomasses are observed along a climate gradient from the Greenland Ice Sheet to offshore waters at the West Greenland coast. The offshore region has a high biomass of copepods dominated by Calanus spp., which are capable of consuming 55....... Protozooplankton accounts for 20-38% of the carbon turnover in the offshore and inland areas. However, protozooplankton like copepods has low ability to turn over the primary production close to the Ice Sheet. Increased run of from the Greenland Ice Sheet due to global warming could displace the existing climate...... gradient. This would have a profound influence on the future plankton community structure as well as the energy transfer to higher trophic levels in Arctic coastal ecosystems....

  17. Ground-Penetrating-Radar Profiles of Interior Alaska Highways: Interpretation of Stratified Fill, Frost Depths, Water Table, and Thaw Settlement over Ice-Rich Permafrost

    Science.gov (United States)

    2016-08-01

    along either massive ice surfaces or within sections of segregated ice. The uninsulated ice surface at Tok in Figure 17B is irregular. All of the...ER D C/ CR RE L TR -1 6- 14 ERDC’s Center-Directed Research Program Ground -Penetrating-Radar Profiles of Interior Alaska Highways...August 2016 Ground -Penetrating-Radar Profiles of Interior Alaska Highways Interpretation of Stratified Fill, Frost Depths, Water Table, and Thaw

  18. Influence of sea ice cover and icebergs on circulation and water mass formation in a numerical circulation model of the Ross Sea, Antarctica

    Science.gov (United States)

    Dinniman, Michael S.; Klinck, John M.; Smith, Walker O.

    2007-11-01

    Satellite imagery shows that there was substantial variability in the sea ice extent in the Ross Sea during 2001-2003. Much of this variability is thought to be due to several large icebergs that moved through the area during that period. The effects of these changes in sea ice on circulation and water mass distributions are investigated with a numerical general circulation model. It would be difficult to simulate the highly variable sea ice from 2001 to 2003 with a dynamic sea ice model since much of the variability was due to the floating icebergs. Here, sea ice concentration is specified from satellite observations. To examine the effects of changes in sea ice due to iceberg C-19, simulations were performed using either climatological ice concentrations or the observed ice for that period. The heat balance around the Ross Sea Polynya (RSP) shows that the dominant term in the surface heat budget is the net exchange with the atmosphere, but advection of oceanic warm water is also important. The area average annual basal melt rate beneath the Ross Ice Shelf is reduced by 12% in the observed sea ice simulation. The observed sea ice simulation also creates more High-Salinity Shelf Water. Another simulation was performed with observed sea ice and a fixed iceberg representing B-15A. There is reduced advection of warm surface water during summer from the RSP into McMurdo Sound due to B-15A, but a much stronger reduction is due to the late opening of the RSP in early 2003 because of C-19.

  19. Effects of sea-ice and biogeochemical processes and storms on under-ice water fCO2 during the winter-spring transition in the high Arctic Ocean: Implications for sea-air CO2 fluxes

    Science.gov (United States)

    Fransson, Agneta; Chierici, Melissa; Skjelvan, Ingunn; Olsen, Are; Assmy, Philipp; Peterson, Algot K.; Spreen, Gunnar; Ward, Brian

    2017-07-01

    We performed measurements of carbon dioxide fugacity (fCO2) in the surface water under Arctic sea ice from January to June 2015 during the Norwegian young sea ICE (N-ICE2015) expedition. Over this period, the ship drifted with four different ice floes and covered the deep Nansen Basin, the slopes north of Svalbard, and the Yermak Plateau. This unique winter-to-spring data set includes the first winter-time under-ice water fCO2 observations in this region. The observed under-ice fCO2 ranged between 315 µatm in winter and 153 µatm in spring, hence was undersaturated relative to the atmospheric fCO2. Although the sea ice partly prevented direct CO2 exchange between ocean and atmosphere, frequently occurring leads and breakup of the ice sheet promoted sea-air CO2 fluxes. The CO2 sink varied between 0.3 and 86 mmol C m-2 d-1, depending strongly on the open-water fractions (OW) and storm events. The maximum sea-air CO2 fluxes occurred during storm events in February and June. In winter, the main drivers of the change in under-ice water fCO2 were dissolution of CaCO3 (ikaite) and vertical mixing. In June, in addition to these processes, primary production and sea-air CO2 fluxes were important. The cumulative loss due to CaCO3 dissolution of 0.7 mol C m-2 in the upper 10 m played a major role in sustaining the undersaturation of fCO2 during the entire study. The relative effects of the total fCO2 change due to CaCO3 dissolution was 38%, primary production 26%, vertical mixing 16%, sea-air CO2 fluxes 16%, and temperature and salinity insignificant.

  20. Abrupt Greenland Ice Sheet runoff and sea water temperature changes since 1821, recorded by coralline algae

    Science.gov (United States)

    Kamenos, N.; Hoey, T.; Bedford, J.; Claverie, T.; Fallick, A. E.; Lamb, C. M.; Nienow, P. W.; O'Neill, S.; Shepherd, I.; Thormar, J.

    2012-12-01

    The Greenland Ice Sheet (GrIS) contains the largest store of fresh water in the northern hemisphere, equivalent to ~7.4m of eustatic sea level rise, but its impacts on current, past and future sea level, ocean circulation and European climate are poorly understood. Previous estimates of GrIS melt, from 26 years of satellite observations and temperature driven melt-models over 48 years, show a trend of increasing melt. There are however no runoff data of comparable duration with which to validate temperature-based runoff models, or relationships between the spatial extent of melt and runoff. Further, longer runoff records that extend GrIS melt records to centennial timescales will enable recently observed trends to be put into a better historical context. We measured Mg/Ca, δ18O and structural cell size in annual growth bands of red coralline algae to reconstruct: (1) near surface sea water temperature; and, (2) melt/runoff from the GrIS. (1) Temperature: we reconstructed the longest (1821-2009) sub-annual resolution record of water temperature in Disko Bugt (western Greenland) showing an abrupt change in temperature oscillation patterns during the 1920s which may be attributable to the interaction between atmospheric temperature and mass loss from Jakobshavn Isbrae glacier. (2) GrIS runoff: using samples from distal parts of Søndre Strømfjord we produced the first reconstruction of decadal (1939-2002) GrIS runoff. We observed significant negative relationships between historic runoff, relative salinity and marine summer temperature. Our reconstruction shows a trend of increasing reconstructed runoff since the mid 1980s. In situ summer marine temperatures followed a similar trend. We suggest that since 1939 atmospheric temperatures have been important in forcing runoff. Subject to locating in situ coralline algae samples, these methods can be applied across hundreds to thousands of years. These results show that our technique has significant potential to enhance

  1. Energetic evaluation of high pressure PEM electrolyzer systems for intermediate storage of renewable energies

    International Nuclear Information System (INIS)

    Bensmann, B.; Hanke-Rauschenbach, R.; Peña Arias, I.K.; Sundmacher, K.

    2013-01-01

    Three pathways for high pressure hydrogen production by means of water electrolysis are energetically compared. Besides the two classic paths, comprising either the pressurization of the product gas (path I) or the mechanical pressurization of the feed water (path II), a third path is discussed. It involves the electrochemical co-compression during the electrolysis. The energetic evaluation is based on a uniform model description of the different hydrogen production pathways. It consists of integral, steady-state balances for energy, entropy and mass as well as a modern equation of state. From this the reversible energy demand is used to identify the inherent thermodynamic drawbacks of the pathways. The additional consideration of irreversibilities allows for the determination of efficiency losses due to device specific characteristics. For hydrogen delivery pressures of up to 40 bar the classical pathways are out-performed by path III. Since the hydrogen is already produced at elevated pressure this eliminates the need for an energy consuming mechanical hydrogen compression and spares the additional energy demand due to the oxygen pressurization. However, with increasing pressure differences the hydrogen back-diffusion strongly decreases the Faradaic efficiency of the asymmetric electrolyzer that has to be compensated by an additional energy supply

  2. Experimental study of the polyamorphism of water. I. The isobaric transitions from amorphous ices to LDA at 4 MPa

    Science.gov (United States)

    Handle, Philip H.; Loerting, Thomas

    2018-03-01

    The existence of more than one solid amorphous state of water is an extraordinary feature. Since polyamorphism might be connected to the liquid-liquid critical point hypothesis, it is particularly important to study the relations amongst the different amorphous ices. Here we study the polyamorphic transformations of several high pressure amorphous ices to low-density amorphous ice (LDA) at 4 MPa by isobaric heating utilising in situ volumetry and ex situ X-ray diffraction. We find that very-high density amorphous ice (VHDA) and unannealed high density amorphous ice (HDA) show significant relaxation before transforming to LDA, whereby VHDA is seen to relax toward HDA. By contrast, expanded HDA shows almost no relaxation prior to the transformation. The transition to LDA itself obeys criteria for a first-order-like transition in all cases. In the case of VHDA, even macroscopic phase separation is observed. These findings suggest that HDA and LDA are two clearly distinct polyamorphs. We further present evidence that HDA reaches the metastable equilibrium at 140 K and 0.1 GPa but only comes close to that at 140 K and 0.2 GPa. The most important is the path independence of the amorphous phase reached at 140 K and 0.1 GPa.

  3. The effects of sub-ice-shelf melting on dense shelf water formation and export in idealized simulations of Antarctic margins

    Science.gov (United States)

    Marques, Gustavo; Stern, Alon; Harrison, Matthew; Sergienko, Olga; Hallberg, Robert

    2017-04-01

    Dense shelf water (DSW) is formed in coastal polynyas around Antarctica as a result of intense cooling and brine rejection. A fraction of this water reaches ice shelves cavities and is modified due to interactions with sub-ice-shelf melt water. This modified water mass contributes to the formation of Antarctic Bottom Water, and consequently, influences the large-scale ocean circulation. Here, we investigate the role of sub-ice-shelf melting in the formation and export of DSW using idealized simulations with an isopycnal ocean model (MOM6) coupled with a sea ice model (SIS2) and a thermodynamic active ice shelf. A set of experiments is conducted with variable horizontal grid resolutions (0.5, 1.0 and 2.0 km), ice shelf geometries and atmospheric forcing. In all simulations DSW is spontaneously formed in coastal polynyas due to the combined effect of the imposed atmospheric forcing and the ocean state. Our results show that sub-ice-shelf melting can significantly change the rate of dense shelf water outflows, highlighting the importance of this process to correctly represent bottom water formation.

  4. Water, Ice, and Meteorological Measurements at South Cascade Glacier, Washington, Balance Years 2004 and 2005

    Science.gov (United States)

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2007-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass-balance quantities for balance years 2004 and 2005. The North Cascade Range in the vicinity of South Cascade Glacier accumulated smaller than normal winter snowpacks during water years 2004 and 2005. Correspondingly, the balance years 2004 and 2005 maximum winter snow balances of South Cascade Glacier, 2.08 and 1.97 meters water equivalent, respectively, were smaller than the average of such balances since 1959. The 2004 glacier summer balance (-3.73 meters water equivalent) was the eleventh most negative during 1959 to 2005 and the 2005 glacier summer balance (-4.42 meters water equivalent) was the third most negative. The relatively small winter snow balances and unusually negative summer balances of 2004 and 2005 led to an overall loss of glacier mass. The 2004 and 2005 glacier net balances, -1.65 and -2.45 meters water equivalent, respectively, were the seventh and second most negative during 1953 to 2005. For both balance years, the accumulation area ratio was less than 0.05 and the equilibrium line altitude was higher than the glacier. The unusually negative 2004 and 2005 glacier net balances, combined with a negative balance previously reported for 2003, resulted in a cumulative 3-year net balance of -6.20 meters water equivalent. No equal or greater 3-year mass loss has occurred previously during the more than 4 decades of U.S. Geological Survey mass-balance measurements at South Cascade Glacier. Accompanying the glacier mass losses were retreat of the terminus and reduction of total glacier area. The terminus retreated at a rate of about 17 meters per year during balance year 2004 and 15 meters per year during balance year 2005. Glacier area near the end of balance years 2004 and 2005 was 1.82 and 1.75 square kilometers, respectively. Runoff from the basin containing the glacier and from an adjacent nonglacierized basin was

  5. Advanced alkaline water electrolysis

    International Nuclear Information System (INIS)

    Marini, Stefania; Salvi, Paolo; Nelli, Paolo; Pesenti, Rachele; Villa, Marco; Berrettoni, Mario; Zangari, Giovanni; Kiros, Yohannes

    2012-01-01

    A short review on the fundamental and technological issues relevant to water electrolysis in alkaline and proton exchange membrane (PEM) devices is given. Due to price and limited availability of the platinum group metal (PGM) catalysts they currently employ, PEM electrolyzers have scant possibilities of being employed in large-scale hydrogen production. The importance and recent advancements in the development of catalysts without PGMs are poised to benefit more the field of alkaline electrolysis rather than that of PEM devices. This paper presents our original data which demonstrate that an advanced alkaline electrolyzer with performances rivaling those of PEM electrolyzers can be made without PGM and with catalysts of high stability and durability. Studies on the advantages/limitations of electrolyzers with different architectures do show how a judicious application of pressure differentials in a recirculating electrolyte scheme helps reduce mass transport limitations, increasing efficiency and power density.

  6. Maximum Evaporation Rates of Water Droplets Approaching Obstacles in the Atmosphere Under Icing Conditions

    Science.gov (United States)

    Lowell, H. H.

    1953-01-01

    When a closed body or a duct envelope moves through the atmosphere, air pressure and temperature rises occur ahead of the body or, under ram conditions, within the duct. If cloud water droplets are encountered, droplet evaporation will result because of the air-temperature rise and the relative velocity between the droplet and stagnating air. It is shown that the solution of the steady-state psychrometric equation provides evaporation rates which are the maximum possible when droplets are entrained in air moving along stagnation lines under such conditions. Calculations are made for a wide variety of water droplet diameters, ambient conditions, and flight Mach numbers. Droplet diameter, body size, and Mach number effects are found to predominate, whereas wide variation in ambient conditions are of relatively small significance in the determination of evaporation rates. The results are essentially exact for the case of movement of droplets having diameters smaller than about 30 microns along relatively long ducts (length at least several feet) or toward large obstacles (wings), since disequilibrium effects are then of little significance. Mass losses in the case of movement within ducts will often be significant fractions (one-fifth to one-half) of original droplet masses, while very small droplets within ducts will often disappear even though the entraining air is not fully stagnated. Wing-approach evaporation losses will usually be of the order of several percent of original droplet masses. Two numerical examples are given of the determination of local evaporation rates and total mass losses in cases involving cloud droplets approaching circular cylinders along stagnation lines. The cylinders chosen were of 3.95-inch (10.0+ cm) diameter and 39.5-inch 100+ cm) diameter. The smaller is representative of icing-rate measurement cylinders, while with the larger will be associated an air-flow field similar to that ahead of an airfoil having a leading-edge radius

  7. Effects of sea-ice light attenuation and CDOM absorption in the water below the Eurasian sector of central Arctic Ocean (>88°N)

    NARCIS (Netherlands)

    Lund-Hansen, L.C.; Markager, S.; Hancke, K.; Stratmann, T.; Rysgaard, S.; Ramløv, H.; Sorrell, B.K.

    2015-01-01

    This is a study of the optical, physical and biological parameters of sea ice and the water below it at stations (n=25) in the central (>88°N) Eurasian sector of the Arctic Ocean during the summer 2012 record low sea-ice minimum extent. Results show that photosynthetically active radiation (PAR)

  8. Attempts to isolate a horizontal high diameter (300 mm nominal diameter) pipeline with an ice plug at minimum water flow and without water flow

    International Nuclear Information System (INIS)

    Corbescu, B.; Gyongyosi, T.; Puiu, D.; Panaitescu, V. N.

    2016-01-01

    The ice plug isolation technique used for high diameter horizontal pipes is used for repair and maintenance activities on hydraulic installations that use liquid working agents. These techniques do not require shutting down the entire plant. The ice plug development inside the pipe requires using custom specialized equipment for each individual application. This paper briefly describes the experimental technological facilities used for conducting the experiments and highlights the important aspects in an experiment conducted on a horizontal NPS 12 testing section running demineralized water followed by the result analysis and conclusions. The paper is dedicated to specialists working in research and technological engineering. (authors)

  9. ADAPTIVE OPTICS OBSERVATIONS OF 3 {mu}m WATER ICE IN SILHOUETTE DISKS IN THE ORION NEBULA CLUSTER AND M43

    Energy Technology Data Exchange (ETDEWEB)

    Terada, Hiroshi; Pyo, Tae-Soo; Minowa, Yosuke; Hayano, Yutaka; Oya, Shin; Hattori, Masayuki; Takami, Hideki [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Tokunaga, Alan T. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Watanabe, Makoto [Department of Cosmosciences, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan); Saito, Yoshihiko [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551 (Japan); Ito, Meguru [Department of Mechanical Engineering, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8P 5C2 (Canada); Iye, Masanori, E-mail: terada@subaru.naoj.org [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2012-12-01

    We present the near-infrared images and spectra of four silhouette disks in the Orion Nebula Cluster (M42) and M43 using the Subaru Adaptive Optics system. While d053-717 and d141-1952 show no water ice feature at 3.1 {mu}m, a moderately deep ({tau}{sub ice} {approx} 0.7) water ice absorption is detected toward d132-1832 and d216-0939. Taking into account the water ice so far detected in the silhouette disks, the critical inclination angle to produce a water ice absorption feature is confirmed to be 65 Degree-Sign -75 Degree-Sign . As for d216-0939, the crystallized water ice profile is exactly the same as in the previous observations taken 3.63 years ago. If the water ice material is located at 30 AU, then the observations suggest it is uniform at a scale of about 3.5 AU.

  10. A Novel Concrete-Based Sensor for Detection of Ice and Water on Roads and Bridges.

    Science.gov (United States)

    Tabatabai, Habib; Aljuboori, Mohammed

    2017-12-14

    Hundreds of people are killed or injured annually in the United States in accidents related to ice formation on roadways and bridge decks. In this paper, a novel embedded sensor system is proposed for the detection of black ice as well as wet, dry, and frozen pavement conditions on roads, runways, and bridges. The proposed sensor works by detecting changes in electrical resistance between two sets of stainless steel poles embedded in the concrete sensor to assess surface and near-surface conditions. A preliminary decision algorithm is developed that utilizes sensor outputs indicating resistance changes and surface temperature. The sensor consists of a 102-mm-diameter, 38-mm-high, concrete cylinder. Laboratory results indicate that the proposed sensor can effectively detect surface ice and wet conditions even in the presence of deicing chlorides and rubber residue. This sensor can further distinguish black ice from ice that may exist within concrete pores.

  11. A Novel Concrete-Based Sensor for Detection of Ice and Water on Roads and Bridges

    Directory of Open Access Journals (Sweden)

    Habib Tabatabai

    2017-12-01

    Full Text Available Hundreds of people are killed or injured annually in the United States in accidents related to ice formation on roadways and bridge decks. In this paper, a novel embedded sensor system is proposed for the detection of black ice as well as wet, dry, and frozen pavement conditions on roads, runways, and bridges. The proposed sensor works by detecting changes in electrical resistance between two sets of stainless steel poles embedded in the concrete sensor to assess surface and near-surface conditions. A preliminary decision algorithm is developed that utilizes sensor outputs indicating resistance changes and surface temperature. The sensor consists of a 102-mm-diameter, 38-mm-high, concrete cylinder. Laboratory results indicate that the proposed sensor can effectively detect surface ice and wet conditions even in the presence of deicing chlorides and rubber residue. This sensor can further distinguish black ice from ice that may exist within concrete pores.

  12. Laboratory and modeling studies on the effects of water and soot emissions and ambient conditions on the properties of contrail ice particles in the jet regime

    Directory of Open Access Journals (Sweden)

    H.-W. Wong

    2013-10-01

    Full Text Available Contrails and contrail-induced cirrus clouds are identified as the most uncertain components in determining aviation impacts on global climate change. Parameters affecting contrail ice particle formation immediately after the engine exit plane (< 5 s in plume age may be critical to ice particle properties used in large-scale models predicting contrail radiative forcing. Despite this, detailed understanding of these parametric effects is still limited. In this paper, we present results from recent laboratory and modeling studies conducted to investigate the effects of water and soot emissions and ambient conditions on near-field formation of contrail ice particles and ice particle properties. The Particle Aerosol Laboratory (PAL at the NASA Glenn Research Center and the Aerodyne microphysical parcel model for contrail ice particle formation were employed. Our studies show that exhaust water concentration has a significant impact on contrail ice particle formation and properties. When soot particles were introduced, ice particle formation was observed only when exhaust water concentration was above a critical level. When no soot or sulfuric acid was introduced, no ice particle formation was observed, suggesting that ice particle formation from homogeneous nucleation followed by homogeneous freezing of liquid water was unfavorable. Soot particles were found to compete for water vapor condensation, and higher soot concentrations emitted into the chamber resulted in smaller ice particles being formed. Chamber conditions corresponding to higher cruising altitudes were found to favor ice particle formation. The microphysical model captures trends of particle extinction measurements well, but discrepancies between the model and the optical particle counter measurements exist as the model predicts narrower ice particle size distributions and ice particle sizes nearly a factor of two larger than measured. These discrepancies are likely due to particle

  13. Anomalous diffusion of water molecules at grain boundaries in ice Ih.

    Science.gov (United States)

    Moreira, Pedro Augusto Franco Pinheiro; Veiga, Roberto Gomes de Aguiar; Ribeiro, Ingrid de Almeida; Freitas, Rodrigo; Helfferich, Julian; de Koning, Maurice

    2018-05-23

    Using ab initio and classical molecular dynamics simulations, we study pre-melting phenomena in pristine coincident-site-lattice grain boundaries (GBs) in proton-disordered hexagonal ice Ih at temperatures just below the melting point Tm. Concerning pre-melt-layer thicknesses, the results are consistent with the available experimental estimates for low-disorder impurity-free GBs. With regard to molecular mobility, the simulations provide a key new insight: the translational motion of the water molecules is found to be subdiffusive for time scales from ∼10 ns up to at least 0.1 μs. Moreover, the fact that the anomalous diffusion occurs even at temperatures just below Tm where the bulk supercooled liquid still diffuses normally suggests that it is related to the confinement of the GB pre-melt layers by the surrounding crystalline environment. Furthermore, we show that this behavior can be characterized by continuous-time random walk models in which the waiting-time distributions decay according to power-laws that are very similar to those describing dynamics in glass-forming systems.

  14. Approximating Matsubara dynamics using the planetary model: Tests on liquid water and ice

    Science.gov (United States)

    Willatt, Michael J.; Ceriotti, Michele; Althorpe, Stuart C.

    2018-03-01

    Matsubara dynamics is the quantum-Boltzmann-conserving classical dynamics which remains when real-time coherences are taken out of the exact quantum Liouvillian [T. J. H. Hele et al., J. Chem. Phys. 142, 134103 (2015)]; because of a phase-term, it cannot be used as a practical method without further approximation. Recently, Smith et al. [J. Chem. Phys. 142, 244112 (2015)] developed a "planetary" model dynamics which conserves the Feynman-Kleinert (FK) approximation to the quantum-Boltzmann distribution. Here, we show that for moderately anharmonic potentials, the planetary dynamics gives a good approximation to Matsubara trajectories on the FK potential surface by decoupling the centroid trajectory from the locally harmonic Matsubara fluctuations, which reduce to a single phase-less fluctuation particle (the "planet"). We also show that the FK effective frequency can be approximated by a direct integral over these fluctuations, obviating the need to solve iterative equations. This modification, together with use of thermostatted ring-polymer molecular dynamics, allows us to test the planetary model on water (gas-phase, liquid, and ice) using the q-TIP4P/F potential surface. The "planetary" fluctuations give a poor approximation to the rotational/librational bands in the infrared spectrum, but a good approximation to the bend and stretch bands, where the fluctuation lineshape is found to be motionally narrowed by the vibrations of the centroid.

  15. Microstructures and mechanical behavior of magnesium processed by ECAP at ice-water temperature

    Science.gov (United States)

    Zuo, Dai; Li, Taotao; Liang, Wei; Wen, Xiyu; Yang, Fuqian

    2018-05-01

    Magnesium of high purity is processed by equal channel angular pressing (ECAP) up to eight passes at the ice-water temperature, in which a core–shell-like structure is used. The core–shell-like structure consists of pure iron (Fe) of 1.5 mm in thickness as the shell and magnesium (Mg) as the core. The microstructure, texture and mechanical behavior of the ECAP-processed Mg are studied. The ECAP processing leads to the formation of fine and equiaxed grains of ~1.1 µm. The basal planes initially parallel to the extrusion direction evolve to slanted basal planes with the tilting angle in a range of 25°–45° to the extrusion direction. Increasing the number of the extrusion passes leads to the decreasing of twins and dislocation density in grains, while individual grains after eight passes still have high dislocation density. The large decreases of twins and the dislocation density make dynamic recrystallization (DRX) difficult, resulting in the decrease of the degree of DRX. Tension test reveals that the mechanical behavior of the ECAP-processed Mg is dependent on grain refinement and textures. The yield strength of the ECAP-extruded Mg first increases with the decrease of the grain size, and then decreases with further decrease of the grain size.

  16. Luminescence as a new detection method for non-relativistic highly ionizing particles in water/ice neutrino telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Pollmann, Anna [Bergische Universitaet Wuppertal (Germany); Collaboration: IceCube-Collaboration

    2016-07-01

    Cosmic ray detectors use air as a radiator for luminescence. In water and ice detectors Cherenkov light is the dominant light producing mechanism when the particle velocity exceeds the Cherenkov threshold, approximately three quarters of the speed of light. Luminescence is produced by highly ionizing particles passing through matter due to the excitation of the surrounding atoms. The observables of luminescence, such as the wavelength spectrum and decay times, are highly dependent on the properties of the medium. Therefore, the results of measurements, in which luminescence was produced by particles passing through water or ice, vary by two orders of magnitude in intensity. It is shown that, even for the most conservative intensity value, luminescence can be used as a detection method for highly ionizing particles with velocities below the Cherenkov threshold. These could be magnetic monopoles or other massive and highly penetrating exotic particles. In the most optimistic case, luminescence contributes even to the light output of standard model particles.

  17. Ikaite crystals in melting sea ice - implications for pCO2 and pH levels in Arctic surface waters

    Science.gov (United States)

    Rysgaard, S.; Glud, R. N.; Lennert, K.; Cooper, M.; Halden, N.; Leakey, R. J. G.; Hawthorne, F. C.; Barber, D.

    2012-08-01

    A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO3·6H2O) in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km2 (0.5-1 m thick) drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice floe thickness by 0.2 m per week and resulted in an estimated 3.8 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 10.6 mmol m-2 sea ice d-1 or to 3.3 ton km-2 ice floe week-1. This is markedly higher than the estimated primary production within the ice floe of 0.3-1.3 mmol m-2 sea ice d-1. Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO2 uptake.

  18. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    Directory of Open Access Journals (Sweden)

    R. J. G. Leakey

    2012-08-01

    Full Text Available A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air–sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO3·6H2O in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km2 (0.5–1 m thick drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice floe thickness by 0.2 m per week and resulted in an estimated 3.8 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air–sea CO2 uptake of 10.6 mmol m−2 sea ice d−1 or to 3.3 ton km−2 ice floe week−1. This is markedly higher than the estimated primary production within the ice floe of 0.3–1.3 mmol m−2 sea ice d−1. Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO2 uptake.

  19. Characterization of the permittivity of controlled porous water ice-dust mixtures to support the radar exploration of icy bodies

    Science.gov (United States)

    Brouet, Y.; Neves, L.; Sabouroux, P.; Levasseur-Regourd, A. C.; Poch, O.; Encrenaz, P.; Pommerol, A.; Thomas, N.; Kofman, W.

    2016-12-01

    The internal properties of porous and icy bodies in the solar system can be investigated by ground-penetrating radars (GPRs), like the COmet Nucleus Sounding Experiment by Radiowave Transmission instrument on board the Rosetta spacecraft which has sounded the interior of the nucleus of comet 67P/Churyumov-Gerasimenko. Accurate constraints on the permittivity of icy media are needed for the interpretation of the data. We report novel permittivity measurements performed on water ice samples and icy mixtures with porosities in the 31-91% range. The measurements have been performed between 50 MHz and 2 GHz with a coaxial cell on a total of 38 samples with a good reproducibility. We used controlled procedures to produce fine-grained and coarse-grained ice samples with a mean diameter of 4.5 μm and 67 μm, respectively, and to prepare icy mixtures. The JSC-1A lunar regolith simulant was used as the dust component in the mixtures. The results are focused on the real-part ɛ' of the permittivity, which constrains the phase velocity of the radio waves in low-loss media. The values of ɛ' show a nondispersive behavior and are within the range of 1.1 to 2.7. They decrease with the increasing porosity Φ according to E(1 - Φ), with E equal to about 3.13 for pure water ice, and in the 3.8-7.5 range for ice-dust mixtures with a dust-to-ice volumetric ratio in the 0.1-2.8 range, respectively. These measurements are also relevant for radiometers operating in the millimeter-submillimeter domains, as suggested by the nondispersive behavior of the mixtures and of the pure components.

  20. Water-Searchers: A Reconfigurable and Self Sustaining Army of Subsurface Exploration Robots Searching for Water/Ice Using Multiple Sensors

    Science.gov (United States)

    Youk, G. U.; Whittaker, W. (Red); Volpe, R.

    2000-01-01

    Perhaps the most promising site for extant life on Mars today is where subsurface water has been maintained. Therefore, searching for underground water will provide a good chance to find evidence of life on Mars. The following are scientific/engineering questions that we want to answer using our approach: (1) Is there subsurface water/ice? How deep is it? How much is there? Is it frozen? (2) What kinds of underground layers exist in the Martian crust? (3) What is the density of Martian soil or regolith? Can we dig into it? Should we drill into it? (4) Can a sudden release of underground water occur if a big asteroid hits Mars? Our approach provides essential information to answer these questions. Moreover, dependence on the water content and depth in soil, not only resultant scientific conclusions but also proper digging/drilling methods, are suggested. 'How much water is in the Martian soil?' There can be several possibilities: (1) high water content that is enough to form permafrost; (2) low water content that is not enough to form permafrost; or (3) different layers with different moisture contents. 'How deep should a rover dig into soil to find water/ice?' The exact size-frequency distribution has not been measured for the soil particles. On-board sensors can provide not only the water content but also the density (or porosity) of Martian soil as a function of depth.

  1. Trapping of CH4, CO, and CO2 in Amorphous Water Ice

    Science.gov (United States)

    Mastrapa, R. M. E.; Brown, R. H.; Anicich, V. G.; Cohen, B. A.; Dai, W.; Lunine, J. I.

    1999-09-01

    In this study, CO, CH4, and CO2 were trapped in H2O at temperatures as low as 20 K and pressures between 10-5 and 10-8 Torr. IR spectra were taken of each sample before sublimation to confirm the presence of volatiles. The samples were then heated at rates from 0.25 K/min to 1 K/min and the escape ranges were measured with a mass spectrometer. The volatiles escaped from the ice mixtures in temperature ranges similar to those found in previous work (1, 2, 3), namely 48-52 K, 145-160 K, 170-185 K. H2O is released from 150 K to 185 K. However, the temperature range of escape is strongly dependent on deposition temperature and heating rate. If the deposition temperature is below the point where the solid volatile rapidly sublimates in the ambient environment of our experiment, then the first range of volatile escape is centered around it's sublimation point, and there is little of the volatile remaining from 170-185 K. The location of the third escape range shifts to lower temperatures with slower sublimation rate. It was determined that 0.5 K/min is the ideal sample heating rate to determine these escape ranges. In our data, the infrared spectrum of CO trapped in water ice shows a splitting of the 2145 cm-1 solid CO line into two bands at 2343 cm-1 and 2135 cm-1. These shifts are similar to those seen by Sandford, et al. (4). (1) Bar-Nun, A., G. Herman, D. Laufer, and M. L. Rappaport, (1985), Icarus, 63, 317-332. (2) Bar-Nun, A., J. Dror, E. Kochavi, and D. Laufer, (1987), Physical Review B, 35, no. 5, 2427-2435. (3) Hudson, R. L., and B. Donn, (1991), Icarus, 94, 326-332. (4) Sandford, S. A., L. J. Allamandola, A. G. G. M. Tielens, and G. J. Valero, (1988), Astrophysical Journal, 329, 498-510.

  2. Characterization of the permittivity of controlled porous water ice-dust mixtures to support the radar exploration of icy bodies

    OpenAIRE

    Brouet, Y.; Neves, L.; Sabouroux, P.; Levasseur-Regourd, A. C.; Poch, O.; Encrenaz, P.; Pommerol, Antoine; Thomas, N.; Kofman, W.

    2016-01-01

    The internal properties of porous and icy bodies in the solar system can be investigated by ground-penetrating radars (GPRs), like the COmet Nucleus Sounding Experiment by Radiowave Transmission instrument on board the Rosetta spacecraft which has sounded the interior of the nucleus of comet 67P/Churyumov-Gerasimenko. Accurate constraints on the permittivity of icy media are needed for the interpretation of the data. We report novel permittivity measurements performed on water ice samples and...

  3. Treatment of infectious skin defects or ulcers with electrolyzed strong acid aqueous solution.

    Science.gov (United States)

    Sekiya, S; Ohmori, K; Harii, K

    1997-01-01

    A chronic ulcer with an infection such as methicillin-resistant Staphylococcus aureus is hard to heal. Plastic and reconstructive surgeons often encounter such chronic ulcers that are resistant to surgical or various conservative treatments. We applied conservative treatment using an electrolyzed strong acid aqueous solution and obtained satisfactory results. The lesion was washed with the solution or soaked in a bowl of the solution for approximately 20 min twice a day. Fresh electrolyzed strong acid aqueous solution is unstable and should be stored in a cool, dark site in a sealed bottle. It should be used within a week after it has been produced. Here we report on 15 cases of infectious ulcers that were treated by electrolyzed strong acid aqueous solution. Of these cases, 7 patients were healed, 3 were granulated, and in 5, infection subsided. In most cases the lesion became less reddish and less edematous. Discharge or foul odor from the lesion was decreased. Electrolyzed strong acid aqueous solution was especially effective for treating a chronic refractory ulcer combined with diabetes melitus or peripheral circulatory insufficiency. This clinically applied therapy of electrolyzed strong acid aqueous solution was found to be effective so that this new therapeutic technique for ulcer treatment can now be conveniently utilized.

  4. Geostatistical analysis and isoscape of ice core derived water stable isotope records in an Antarctic macro region

    Science.gov (United States)

    Hatvani, István Gábor; Leuenberger, Markus; Kohán, Balázs; Kern, Zoltán

    2017-09-01

    Water stable isotopes preserved in ice cores provide essential information about polar precipitation. In the present study, multivariate regression and variogram analyses were conducted on 22 δ2H and 53 δ18O records from 60 ice cores covering the second half of the 20th century. Taking the multicollinearity of the explanatory variables into account, as also the model's adjusted R2 and its mean absolute error, longitude, elevation and distance from the coast were found to be the main independent geographical driving factors governing the spatial δ18O variability of firn/ice in the chosen Antarctic macro region. After diminishing the effects of these factors, using variography, the weights for interpolation with kriging were obtained and the spatial autocorrelation structure of the dataset was revealed. This indicates an average area of influence with a radius of 350 km. This allows the determination of the areas which are as yet not covered by the spatial variability of the existing network of ice cores. Finally, the regional isoscape was obtained for the study area, and this may be considered the first step towards a geostatistically improved isoscape for Antarctica.

  5. Chemistry in the Dunes of Titan: Tribochemical Reactions of Complex Organics and Water Ice

    Science.gov (United States)

    Beauchamp, J. L.; Thomas, D. A.

    2010-12-01

    Titan’s N2-CH4 atmosphere provides the starting material for a wide array of organic compounds to be formed via photochemistry, and the presence of unsaturated hydrocarbon, amine, and polycyclic aromatic species has been supported by data from the Cassini-Huygens mission [1,2]. Production of tholins by UV irradiation of a simulated N2-CH4 environment has yielded products that match the observed optical properties of Titan haze, suggesting that these compounds provide suitable analogs to Titan aerosol compounds [3, 4, 5]. Organics produced in Titan’s atmosphere eventually settle to the surface and very likely contribute to the particulate matter comprising the expansive longitudinal dune features observed at mid-latitudes [6]. Once on the surface, conditions that lead to incorporation of oxygen via contact with water ice or liquid water in Titan’s low temperature environment are of particular interest and have important implications for astrobiology [7; 8]. In this work, we postulate that the mechanical energy from wind-driven grains in the dunes of Titan can ultimately drive chemical processes and lead to the incorporation of oxygen into organic compounds via tribochemical reactions [9] and describe experiments designed to test this hypothesis. While the exact composition of the dunes of Titan is unknown, it is likely that they mainly comprise organic and water ice particles approximately 0.2 mm in diameter, the ideal size for saltation by the winds of Titan [6]. During the saltation process, organic particles undergo charging due to friction between particles, leading in turn to formation of ions and free radicals in localized electrical discharges at particle interfaces [10]. These reactive intermediates can initiate processes such as free radical and ionic polymerization that further transform organics. Of particular interest is the incorporation of oxygen into organic molecules, providing a pathway to the synthesis of biologically relevant compounds

  6. Laser-induced plasma from pure and doped water-ice at high fluence by ultraviolet and infrared radiation - art. no. 70050X

    DEFF Research Database (Denmark)

    Schou, Jørgen; Matei, A.; Rodrigo, Katarzyna Agnieszka

    2008-01-01

    Ice made of ultrapure water or water doped with 1 % polymer (polyethylene glycol, "PEG") was irradiated by laser light with fluences between 2 and 80 J/cm(2) in the ultraviolet (UV) regime at 355 nm and in the infrared (IR) regime at 1064 nm in vacuum. In the UV regime there is a threshold for pl...... of ionization breakdown at the ice surface....

  7. JAWS: Just Add Water System - A device for detection of nucleic acids in Martian ice caps

    DEFF Research Database (Denmark)

    Hansen, Anders J.; Willerslev, Eske; Mørk, Søren

    2002-01-01

    with a regulation of pH and salt concentrations e.g. the MOD systems and could be installed on a planetary probe melting its way down the Martian ice caps e.g. the NASA Cryobot. JAWS can be used for detection of remains of ancient life preserved in the Martian ice as well as for detection of contamination brought...... to the planet from Earth....

  8. Design of electrodes in geometrical control type electrolyzer for oxide electrowinning process

    International Nuclear Information System (INIS)

    Nobuo Okamura; Kenji Koizumi; Tadahiro Washiya; Shinnichi Aose

    2005-01-01

    Japan Nuclear Cycle Development Institute (JNC) has been developing a commercial scale electrolyzer with a throughput of 25 tHM/y for an oxide electrowinning process, a kind of pyrochemical reprocessing process. But it had some significant subjects to be solved before the application to a commercial reprocessing plant. The electrolyzer has some innovative characteristics, such as cold crucible induction melting (CCIM) technology and criticality safety control by shape of the vessel, in order to solve those subjects. These characteristics make a crucible narrow and deep. Therefore an arrangement of the internal components in the crucible is difficult. Two kinds of computer cords that evaluate the temperature distribution and the current density distribution were improved to help a design of the internal constitution. Finally, the internal constitution of the commercial scale electrolyzer was designed by using them in this study. (authors)

  9. Application of electrolyzer system to enhance frequency stabilization effect of microturbine in a microgrid system

    Energy Technology Data Exchange (ETDEWEB)

    Vachirasricirikul, Sitthidet [Department of Electrical Engineering, Faculty of Engineering, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Ngamroo, Issarachai; Kaitwanidvilai, Somyot [Center of Excellence for Innovative Energy Systems, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand)

    2009-09-15

    It is well known that the power output of microturbine can be controlled to compensate for load change and alleviate the system frequency fluctuations. Nevertheless, the microturbine may not adequately compensate rapid load change due to its slow dynamic response. Moreover, when the intermittent power generations from wind power and photovoltaic are integrated into the system, they may cause severe frequency fluctuation. In order to study the fast dynamic response, this paper applies electrolyzer system to absorb these power fluctuations and enhance the frequency control effect of microturbine in the microgrid system. The robust coordinated controller of electrolyzer and microturbine for frequency stabilization is designed based on a fixed-structure H{sub {infinity}} loop shaping control. Simulation results exhibit the robustness and stabilizing effects of the proposed coordinated electrolyzer and microturbine controllers against system parameters variation and various operating conditions. (author)

  10. Observing Ice Sublimation From Water-Doped Lunar Simulant at Cryogenic Temperatures

    Science.gov (United States)

    Roush, T. L.; Teodoro, L. F. A.; Colaprete, A.; Cook, A. M.; Elphic, R.

    2018-01-01

    NASA's Resource Prospector (RP) mission is intended to characterize the three-dimensional nature of volatiles in lunar polar and permanently shadowed regions. The Near-Infrared Volatile Spectrometer System (NIRVSS) observes while a drill penetrates to a maximum depth of 1 m. Any 10 cm increment of soil identified as containing water ice can be delivered to a heating crucible with the evolved gas delivered to a gas chromatograph / mass spectrometer. NIRVSS consists of two components; a spectrometer box (SB) and bracket assembly (BA), connected by two fiber optic cables. The SB contains separate short- and long-wavelength spectrometers, SW and LW respectively, that collectively span the 1600-3400 nm range. The BA contains an IR emitter (lamp), drill observation camera (DOC, 2048 x 2048 CMOS detector), 8 different wavelength LEDs, and a longwave calibration sensor (LCS) measuring the surface emissivity at four IR wavelengths. Tests of various RP sub-systems have been under-taken in a large cryo-vacuum chamber at Glenn Re-search Center. The chamber accommodates a tube (1.2 m high x 25.4 cm diameter) filled with lunar simulant, NU-LHT-3M, prepared with known abundances of water. Thermocouples are embedded at different depths, and also across the surface of the soil tube. In the chamber the tube is cooled with LN2 as the pressure is reduced to approx. 5-6x10(exp -6) Torr. For the May 2016 tests two soil tubes were prepared with initially 2.5 Wt.% water. The shroud surrounding the soil tube was held at different temperatures for each tube to simulate a warm and cold lunar environment. Table 1 provides a summary of experimental conditions and Figure 1 shows the nominal view of the NIRVSS components, the drill foot, and the top of the soil tube. Once the average soil temperature reached approx. 178 K, drilling commenced. During drilling activities NIRVSS was alternating between obtaining spectra and obtaining images. Here we discuss NIRVSS spectral data obtained during

  11. Phase separation of acetonitrile-water mixtures and minimizing of ice crystallites from there in confinement of MCM-41.

    Science.gov (United States)

    Kittaka, Shigeharu; Kuranishi, Miki; Ishimaru, Shinji; Umahara, Osamu

    2007-03-07

    The effect of confinement of an acetonitrile-water mixture, whose correlation length was comparable to the pore size of the mesopores of MCM-41 (d=2.4-3.6 nm), on the phase changes was studied. Used techniques were low temperature differential scanning calorimetry and Fourier transform infrared spectroscopy, where the phase separation, lowering of the freezing and melting temperatures, and phase transitions of the acetonitrile were detected. The latter occurred in the mesopores at temperatures similar to that of the pure liquid, while the melting temperature of the water in the mesopores<3.1 nm decreased markedly at higher acetonitrile contents, suggesting a marked lowering of ice crystallite size.

  12. Open-water and under-ice seasonal variations in trace element content and physicochemical associations in fluvial bed sediment.

    Science.gov (United States)

    Doig, Lorne E; Carr, Meghan K; Meissner, Anna G N; Jardine, Tim D; Jones, Paul D; Bharadwaj, Lalita; Lindenschmidt, Karl-Erich

    2017-11-01

    Across the circumpolar world, intensive anthropogenic activities in the southern reaches of many large, northward-flowing rivers can cause sediment contamination in the downstream depositional environment. The influence of ice cover on concentrations of inorganic contaminants in bed sediment (i.e., sediment quality) is unknown in these rivers, where winter is the dominant season. A geomorphic response unit approach was used to select hydraulically diverse sampling sites across a northern test-case system, the Slave River and delta (Northwest Territories, Canada). Surface sediment samples (top 1 cm) were collected from 6 predefined geomorphic response units (12 sites) to assess the relationships between bed sediment physicochemistry (particle size distribution and total organic carbon content) and trace element content (mercury and 18 other trace elements) during open-water conditions. A subset of sites was resampled under-ice to assess the influence of season on these relationships and on total trace element content. Concentrations of the majority of trace elements were strongly correlated with percent fines and proxies for grain size (aluminum and iron), with similar trace element grain size/grain size proxy relationships between seasons. However, finer materials were deposited under ice with associated increases in sediment total organic carbon content and the concentrations of most trace elements investigated. The geomorphic response unit approach was effective at identifying diverse hydrological environments for sampling prior to field operations. Our data demonstrate the need for under-ice sampling to confirm year-round consistency in trace element-geochemical relationships in fluvial systems and to define the upper extremes of these relationships. Whether contaminated or not, under-ice bed sediment can represent a "worst-case" scenario in terms of trace element concentrations and exposure for sediment-associated organisms in northern fluvial systems

  13. The Mars Dust Cycle: Investigating the Effects of Radiatively Active Water Ice Clouds on Surface Stresses and Dust Lifting Potential with the NASA Ames Mars General Circulation Model

    Science.gov (United States)

    Kahre, Melinda A.; Hollingsworth, Jeffery

    2012-01-01

    The dust cycle is a critically important component of Mars' current climate system. Dust is present in the atmosphere of Mars year-round but the dust loading varies with season in a generally repeatable manner. Dust has a significant influence on the thermal structure of the atmosphere and thus greatly affects atmospheric circulation. The dust cycle is the most difficult of the three climate cycles (CO2, water, and dust) to model realistically with general circulation models. Until recently, numerical modeling investigations of the dust cycle have typically not included the effects of couplings to the water cycle through cloud formation. In the Martian atmosphere, dust particles likely provide the seed nuclei for heterogeneous nucleation of water ice clouds. As ice coats atmospheric dust grains, the newly formed cloud particles exhibit different physical and radiative characteristics. Thus, the coupling between the dust and water cycles likely affects the distributions of dust, water vapor and water ice, and thus atmospheric heating and cooling and the resulting circulations. We use the NASA Ames Mars GCM to investigate the effects of radiatively active water ice clouds on surface stress and the potential for dust lifting. The model includes a state-of-the-art water ice cloud microphysics package and a radiative transfer scheme that accounts for the radiative effects of CO2 gas, dust, and water ice clouds. We focus on simulations that are radiatively forced by a prescribed dust map, and we compare simulations that do and do not include radiatively active clouds. Preliminary results suggest that the magnitude and spatial patterns of surface stress (and thus dust lifting potential) are substantial influenced by the radiative effects of water ice clouds.

  14. Freezing on a Chip—A New Approach to Determine Heterogeneous Ice Nucleation of Micrometer-Sized Water Droplets

    Directory of Open Access Journals (Sweden)

    Thomas Häusler

    2018-04-01

    Full Text Available We are presenting a new approach to analyze the freezing behavior of aqueous droplets containing ice nucleating particles. The freezing chip consists of an etched and sputtered (15 × 15 × 1 mm gold-plated silicon or pure gold chip, enabling the formation of droplets with defined diameters between 20 and 80 µm. Several applications like an automated process control and an automated image evaluation were implemented to improve the quality of heterogeneous freezing experiments. To show the functionality of the setup, we compared freezing temperatures of aqueous droplets containing ice nucleating particles (i.e., microcline, birch pollen washing water, juniper pollen, and Snomax® solution measured with our setup, with literature data. The ice nucleation active surface/mass site density (ns/m of microcline, juniper pollen, and birch pollen washing water are shown to be in good agreement with literature data. Minor variations can be explained by slight differences in composition and droplet generation technique. The nm values of Snomax® differ by up to one order of magnitude at higher subzero temperatures when compared with fresh samples but are in agreement when compared with reported data of aged Snomax® samples.

  15. Introducing the North Water: Histories of exploration, ice dynamics, living resources, and human settlement in the Thule Region.

    Science.gov (United States)

    Hastrup, Kirsten; Mosbech, Anders; Grønnow, Bjarne

    2018-04-01

    The North Water is a recurrent polynya in the High Arctic situated between Northwest Greenland and Ellesmere Island of Canada. The North Water makes a dynamic space, where various processes may enhance or obstruct each other, accelerating or halting particular modes of human-animal relations in the region, where life itself depends on the North Water. This will be discussed in four steps. The first step posits the North Water as a perceived oasis for explorers and whalers hailing from Europe or America in the nineteenth century. The second step concentrates on the diverse rhythms inherent in the ice conditions, as affected by trends that are set in motion elsewhere. The third step highlights the implications of the dynamics of the ice and sea currents for animal life in the region. The fourth step gives an overview of human settlement patterns around the North Water across the ages. The article shows how natural and social features are deeply implicated in each other, even if they are not directly co-variant.

  16. High Performance Fuel Cell and Electrolyzer Membrane Electrode Assemblies (MEAs) for Space Energy Storage Systems

    Science.gov (United States)

    Valdez, Thomas I.; Billings, Keith J.; Kisor, Adam; Bennett, William R.; Jakupca, Ian J.; Burke, Kenneth; Hoberecht, Mark A.

    2012-01-01

    Regenerative fuel cells provide a pathway to energy storage system development that are game changers for NASA missions. The fuel cell/ electrolysis MEA performance requirements 0.92 V/ 1.44 V at 200 mA/cm2 can be met. Fuel Cell MEAs have been incorporated into advanced NFT stacks. Electrolyzer stack development in progress. Fuel Cell MEA performance is a strong function of membrane selection, membrane selection will be driven by durability requirements. Electrolyzer MEA performance is catalysts driven, catalyst selection will be driven by durability requirements. Round Trip Efficiency, based on a cell performance, is approximately 65%.

  17. Regenerative Hydrogen-oxygen Fuel Cell-electrolyzer Systems for Orbital Energy Storage

    Science.gov (United States)

    Sheibley, D. W.

    1984-01-01

    Fuel cells have found application in space since Gemini. Over the years technology advances have been factored into the mainstream hardware programs. Performance levels and service lives have been gradually improving. More recently, the storage application for fuel cell-electrolyzer combinations are receiving considerable emphasis. The regenerative system application described here is part of a NASA Fuel Cell Program which was developed to advance the fuel cell and electrolyzer technology required to satisfy the identified power generation and energy storage need of the Agency for space transportation and orbital applications to the year 2000.

  18. On the observation of unusual high concentration of small chain-like aggregate ice crystals and large ice water contents near the top of a deep convective cloud during the CIRCLE-2 experiment

    Science.gov (United States)

    Gayet, J.-F.; Mioche, G.; Bugliaro, L.; Protat, A.; Minikin, A.; Wirth, M.; Dörnbrack, A.; Shcherbakov, V.; Mayer, B.; Garnier, A.; Gourbeyre, C.

    2012-01-01

    During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/-58 °C). The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique set of instruments for the extensive in situ cloud measurements of microphysical and optical properties (Polar Nephelometer, FSSP-300, Cloud Particle Imager and PMS 2-D-C) and nadir looking remote sensing observations (DLR WALES Lidar). Quasi-simultaneous space observations from MSG/SEVIRI, CALIPSO/CALIOP-WFC-IIR and CloudSat/CPR combined with airborne RASTA radar reflectivity from the French Falcon aircraft flying above the DLR Falcon depict very well convective cells which overshoot by up to 600 m the tropopause level. Unusual high values of the concentration of small ice particles, extinction, ice water content (up to 70 cm-3, 30 km-1 and 0.5 g m-3, respectively) are experienced. The mean effective diameter and the maximum particle size are 43 μm and about 300 μm, respectively. This very dense cloud causes a strong attenuation of the WALES and CALIOP lidar returns. The SEVIRI retrieved parameters confirm the occurrence of small ice crystals at the top of the convective cell. Smooth and featureless phase functions with asymmetry factors of 0.776 indicate fairly uniform optical properties. Due to small ice crystals the power-law relationship between ice water content (IWC) and radar reflectivity appears to be very different from those usually found in cirrus and anvil clouds. For a given equivalent reflectivity factor, IWCs are significantly larger for the overshooting cell than for the cirrus. Assuming the same prevalent microphysical properties over the depth of the overshooting cell, RASTA reflectivity profiles scaled into ice water content show that retrieved IWC up to 1 g m-3 may be observed near the cloud top

  19. On the observation of unusual high concentration of small chain-like aggregate ice crystals and large ice water contents near the top of a deep convective cloud during the CIRCLE-2 experiment

    Directory of Open Access Journals (Sweden)

    J.-F. Gayet

    2012-01-01

    Full Text Available During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/−58 °C. The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique set of instruments for the extensive in situ cloud measurements of microphysical and optical properties (Polar Nephelometer, FSSP-300, Cloud Particle Imager and PMS 2-D-C and nadir looking remote sensing observations (DLR WALES Lidar. Quasi-simultaneous space observations from MSG/SEVIRI, CALIPSO/CALIOP-WFC-IIR and CloudSat/CPR combined with airborne RASTA radar reflectivity from the French Falcon aircraft flying above the DLR Falcon depict very well convective cells which overshoot by up to 600 m the tropopause level. Unusual high values of the concentration of small ice particles, extinction, ice water content (up to 70 cm−3, 30 km−1 and 0.5 g m−3, respectively are experienced. The mean effective diameter and the maximum particle size are 43 μm and about 300 μm, respectively. This very dense cloud causes a strong attenuation of the WALES and CALIOP lidar returns. The SEVIRI retrieved parameters confirm the occurrence of small ice crystals at the top of the convective cell. Smooth and featureless phase functions with asymmetry factors of 0.776 indicate fairly uniform optical properties. Due to small ice crystals the power-law relationship between ice water content (IWC and radar reflectivity appears to be very different from those usually found in cirrus and anvil clouds. For a given equivalent reflectivity factor, IWCs are significantly larger for the overshooting cell than for the cirrus. Assuming the same prevalent microphysical properties over the depth of the overshooting cell, RASTA reflectivity profiles scaled into ice water content show that retrieved

  20. Creep of ice: further studies

    International Nuclear Information System (INIS)

    Heard, H.C.; Durham, W.B.; Kirby, S.H.

    1987-01-01

    Detailed studies have been done of ice creep as related to the icy satellites, Ganymede and Callisto. Included were: (1) the flow of high-pressure water ices II, III, and V, and (2) frictional sliding of ice I sub h. Work was also begun on the study of the effects of impurities on the flow of ice. Test results are summarized

  1. Pronounced anomalies of air, water, ice conditions in the Barents and Kara Seas, and the Sea of Azov

    Directory of Open Access Journals (Sweden)

    Gennady G. Matishov

    2014-06-01

    Full Text Available This paper analyses the anomalous hydrometeorological situation that occurred at the beginning of 2012 in the seas of the Russian Arctic and Russian South. Atmospheric blocking in the temperate zone and the extension of the Siberian High to the Iberian Peninsula (known as the Voeikov et al. axis led to a positive anomaly of air and water temperatures and a decrease in the ice extent in the Barents and Kara Seas. At the same time a prolonged negative air temperature anomaly was recorded in central and southern Europe and led to anomalously severe ice conditions in the Sea of Azov. Winter hydrographic conditions in the Barents and Kara Seas are illustrated by a unique set of observations made using expendable bathythermosalinographs (XCTD.

  2. Diurnal variations of humidity and ice water content in the tropical upper troposphere

    Directory of Open Access Journals (Sweden)

    P. Eriksson

    2010-12-01

    Full Text Available Observational results of diurnal variations of humidity from Odin-SMR and AURA-MLS, and cloud ice mass from Odin-SMR and CloudSat are presented for the first time. Comparisons show that the retrievals of humidity and cloud ice from these two satellite combinations are in good agreement. The retrieved data are combined from four almost evenly distributed times of the day allowing mean values, amplitudes and phases of the diurnal variations around 200 hpa to be estimated. This analysis is applied to six climatologically distinct regions, five located in the tropics and one over the subtropical northern Pacific Ocean. The strongest diurnal cycles are found over tropical land regions, where the amplitude is ~7 RHi for humidity and ~50% for ice mass. The greatest ice mass for these regions is found during the afternoon, and the humidity maximum is observed to lag this peak by ~6 h. Over tropical ocean regions the variations are smaller and the maxima in both ice mass and humidity are found during the early morning. Observed results are compared with output from three climate models (ECHAM, EC-EARTH and CAM3. Direct measurement-model comparisons were not possible because the measured and modelled cloud ice masses represent different quantities. To make a meaningful comparison, the amount of snow had to be estimated from diagnostic parameters of the models. There is a high probability that the models underestimate the average ice mass (outside the 1-σ uncertainty. The models also show clear deficiencies when it comes to amplitude and phase of the regional variations, but to varying degrees.

  3. Phytodesalinization potential of Typha angustifolia, Juncus maritimus, and Eleocharis palustris for removal of de-icing salts from runoff water.

    Science.gov (United States)

    Guesdon, Gaëlle; de Santiago-Martín, Ana; Galvez-Cloutier, Rosa

    2016-10-01

    Typha angustifolia, Juncus maritimus, and Eleocharis palustris were evaluated for de-icing salt removal from runoff water. Plants were exposed to a range of de-icing salt levels (0.2, 0.7, 4, 8, and 13 dS m(-1)) in laboratory-scale subsurface constructed wetlands (CWs) for 2 months under greenhouse conditions. Effluent characteristics, plant height, biomass, and Cl and Na removal rates and uptake were monitored. More water volume was retained in CWs of T. angustifolia (∼60 %) than of J. maritimus and E. palustris (∼37.5 %), which accounted for the electrical conductivity increase in effluents (1.3-1.9-fold). Based on the NaCl removal rate, T. angustifolia showed the greatest phytodesalinization ability (31-60 %) with the highest removal at the lowest salt levels (0.2-0.7 dS m(-1)), followed by J. maritimus (22-36 %) without differences in removal among levels, and E. palustris (3-26 %) presenting a removal rate highly decreased with increasing salt levels. Plant height and biomass were stimulated at low de-icing salt levels, but, at higher levels, T. angustifolia and E. palustris growth was inhibited (tolerance index ∼67 and 10 %, respectively, in the worst cases). Salt amounts in aboveground biomass in g m(-2) differed among levels and ranged as follows: 13.6-29.1 (Cl), 4.2-9.3 (Na; T. angustifolia); 7.0-12.0 (Cl), 2.7-6.4 (Na; J. maritimus); and 0.9-7.6 (Cl), 0.3-1.6 (Na; E. palustris). Chloride and Na translocation decreased with de-icing salt increase in T. angustifolia, while no significant differences were found in J. maritimus, which is interesting for harvesting purposes.

  4. Muscle Reaction Time During a Simulated Lateral Ankle Sprain After Wet-Ice Application or Cold-Water Immersion.

    Science.gov (United States)

    Thain, Peter K; Bleakley, Christopher M; Mitchell, Andrew C S

    2015-07-01

    Cryotherapy is used widely in sport and exercise medicine to manage acute injuries and facilitate rehabilitation. The analgesic effects of cryotherapy are well established; however, a potential caveat is that cooling tissue negatively affects neuromuscular control through delayed muscle reaction time. This topic is important to investigate because athletes often return to exercise, rehabilitation, or competitive activity immediately or shortly after cryotherapy. To compare the effects of wet-ice application, cold-water immersion, and an untreated control condition on peroneus longus and tibialis anterior muscle reaction time during a simulated lateral ankle sprain. Randomized controlled clinical trial. University of Hertfordshire human performance laboratory. A total of 54 physically active individuals (age = 20.1 ± 1.5 years, height = 1.7 ± 0.07 m, mass = 66.7 ± 5.4 kg) who had no injury or history of ankle sprain. Wet-ice application, cold-water immersion, or an untreated control condition applied to the ankle for 10 minutes. Muscle reaction time and muscle amplitude of the peroneus longus and tibialis anterior in response to a simulated lateral ankle sprain were calculated. The ankle-sprain simulation incorporated a combined inversion and plantar-flexion movement. We observed no change in muscle reaction time or muscle amplitude after cryotherapy for either the peroneus longus or tibialis anterior (P > .05). Ten minutes of joint cooling did not adversely affect muscle reaction time or muscle amplitude in response to a simulated lateral ankle sprain. These findings suggested that athletes can safely return to sporting activity immediately after icing. Further evidence showed that ice can be applied before ankle rehabilitation without adversely affecting dynamic neuromuscular control. Investigation in patients with acute ankle sprains is warranted to assess the clinical applicability of these interventions.

  5. A natural ice boom

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, H.R. [Manitoba Hydro, Winnipeg, MB (Canada)

    1998-10-01

    Planning for ice jams and ice movements are critical on the Nelson River in northern Manitoba in designing cofferdams. Experience on the St. Lawrence River demonstrated the possibility of exercising some control over ice action by judicious placement of log booms or ice control structures. The success of experiments with man-made controls led to field tests in which an ice sheet of sufficient magnitude and competence was introduced into the open water stream of the Nelson River. The ice sheet was subsequently jammed in a narrow channel, thereby creating a natural ice bridge or boom upstream of a proposed hydro development. Under favourable conditions, this boom would initiate the progression of the ice cover from its location upstream, cutting off the downstream reach from the ice producing potential of the upstream reach. Although ice would still be generated downstream, the length of the reach between the ice boom and the development site would be short enough that ice jamming at the development site would never occur. Although problems in blasting prevented the introduction of a competent ice sheet into the main stream of the river at the location chosen, sufficient confidence in the theory was gained to warrant further consideration. 4 refs., 1 tab., 10 figs.

  6. A simple trapping method of exhaled water using an ice-cooled tube to monitor the tritium level in human body

    International Nuclear Information System (INIS)

    Nogawa, Norio; Makide, Yoshihiro

    1994-01-01

    A convenient and efficient method is developed for the trapping of water in exhaled air. A bent-V-shaped glass sampling tube was immersed in iced water and exhaled air was introduced into the tube through a plastic straw. The trapping efficiency of exhaled water was equivalent to those with more complex and troublesome methods. Using anywhere available ice, the water in exhaled air can be rapidly collected with this method and the tritium level in the body will be quickly obtained. (author)

  7. Rate of ice accumulation during ice storms

    Energy Technology Data Exchange (ETDEWEB)

    Feknous, N. [SNC-Lavalin, Montreal, PQ (Canada); Chouinard, L. [McGill Univ., Montreal, PQ (Canada); Sabourin, G. [Hydro-Quebec, Montreal, PQ (Canada)

    2005-07-01

    The rate of glaze ice accumulation is the result of a complex process dependent on numerous meteorological and physical factors. The aim of this paper was to estimate the distribution rate of glaze ice accumulation on conductors in southern Quebec for use in the design of mechanical and electrical de-icing devices. The analysis was based on direct observations of ice accumulation collected on passive ice meters. The historical database of Hydro-Quebec, which contains observations at over 140 stations over period of 25 years, was used to compute accumulation rates. Data was processed so that each glaze ice event was numbered in a chronological sequence. Each event consisted of the time series of ice accumulations on each of the 8 cylinders of the ice meters, as well as on 5 of its surfaces. Observed rates were converted to represent the average ice on a 30 mm diameter conductor at 30 m above ground with a span of 300 m. Observations were corrected to account for the water content of the glaze ice as evidenced by the presence of icicles. Results indicated that despite significant spatial variations in the expected severity of ice storms as a function of location, the distribution function for rates of accumulation were fairly similar and could be assumed to be independent of location. It was concluded that the observations from several sites could be combined in order to obtain better estimates of the distribution of hourly rates of ice accumulation. However, the rates were highly variable. For de-icing strategies, it was suggested that average accumulation rates over 12 hour periods were preferable, and that analyses should be performed for other time intervals to account for the variability in ice accumulation rates over time. In addition, accumulation rates did not appear to be highly correlated with average wind speed for maximum hourly accumulation rates. 3 refs., 2 tabs., 10 figs.

  8. Measurements of the Ice Water Content of Cirrus in the Tropics and Subtropics. I; Instrument Details and Validation

    Science.gov (United States)

    Weinstock, E. M.; Smith, J. B.; Sayres, D.; Pittman, J. V.; Allen, N.; Demusz, J.; Greenberg, M.; Rivero, M.; Anderson, J. G.

    2003-01-01

    We describe an instrument mounted in a pallet on the NASA WB-57 aircraft that is designed to measure the sum of gas phase and solid phase water, or total water, in cirrus clouds. Using an isokinetic inlet, a 600-watt heater mounted directly in the flow, and Lyman-alpha photofragment fluorescence technique for detection, accurate measurements of total water have been made over almost three orders of magnitude. Isokinetic flow is achieved with an actively controlled roots pump by referencing aircraft pressure, temperature, and true air speed, together with instrument flow velocity, temperature, and pressure. During CRYSTAL FACE, the instrument operated at duct temperatures sufficiently warm to completely evaporate particles up to 150 microns diameter. In flight diagnostics, intercomparison with water measured by absorption in flight, as well as intercomparisons in clear air with water vapor measured by the Harvard water vapor instrument and the JPL infrared tunable diode laser hygrometer validate the detection sensitivity of the instrument and illustrate minimal hysteresis from instrument surfaces. The simultaneous measurement of total water and water vapor in cirrus clouds yields their ice water content.

  9. A reversible electrolyzer-fuel cell system based on PEM technology

    International Nuclear Information System (INIS)

    Grigoriev, S.A.; Millet, P.; Fateev, V.N.

    2009-01-01

    'Full text': A reversible electrolyzer-fuel cell is an electrochemical system which can be alternatively operated in water electrolysis or H 2 /O 2 (air) fuel cell modes. Whereas proton-exchange membrane (PEM) water electrolysis and PEM fuel cell technologies are individually well-established, it is still a very challenging task to develop efficient reversible systems which can maintain interesting electrochemical performances during a significant number of cycles. Results reported in this communication are related to R and D on bi-functional catalysts, electrocatalytic layers, gas diffusion layers/current collectors and reversible PEM stack design. Electrodes which do not change their redox status when the operation mode of the cell is switched from electrolysis to fuel cell are more specifically considered. In particular, it is shown that, when the anode is composed of Pt-Ir layers (ca. 0.5/0.5 wt. ratio), best electrochemical performances are obtained (for both for water and hydrogen oxidation reactions) when an Ir layer is placed face-to-face with the membrane. Cathodic electrocatalytic layers made of Pt/C were prepared and optimized by adding PTFE to obtain the required hydrophobic-hydrophilic properties for effective oxygen and protons electro-reduction. Gas diffusion electrodes made of porous carbon materials and bi-porous titanium sheets with appropriate water management properties have also been developed. A two-cell stack with 250 cm 2 active area electrodes has been assembled using the optimized components and successfully tested. Results are rather close to those obtained for individual water electrolysis and H 2 /O 2 fuel cells with the same noble metal loadings and similar operating conditions. For instance, at a current density of 0.2 A/cm 2 , typical cell voltages of ca. 1.55 and 0.70 V were respectively obtained during water electrolysis and H 2 /O 2 fuel cell operation, using Nafion-1135 as solid polymer electrolyte and noble metal loadings 2

  10. Effect of cryotherapy on the ankle temperature in athletes: ice pack and cold water immersion

    Directory of Open Access Journals (Sweden)

    Vanessa Batista da Costa Santos

    Full Text Available Introduction Cryotherapy is often used for rehabilitation of injured athletes. Objective To compare the effectiveness of ice pack (IP and cold water immersion (CWI on lowering the ankle skin surface temperature in athletes. Materials and methods Thirteen athletes (seven women and six men, age 19.53 (± 2.9 years. IP and CWI were applied on the anterior talofibular ligament (ATFL of the dominant leg for 30 minutes. The skin surface temperature was measured with an infrared digital thermometer prior to the application and during cryotherapy (10, 15, 20, 25 and 30 minutes and up to two hours of rewarming. During rewarming, the athletes remained at rest and the temperature was measured every 1 minute until 10 minutes, every 5 minutes for up to an hour and every 15 minutes until 2 hours. Results The two types of cold application were effective in lowering the skin surface temperature after the 30-minute procedure. Significant differences were observed among the following temperatures: pre-application (IP = 29.8 ± 2.4 °C and CWI = 27.5 ± 3 °C – P < 0.05; after 30 minutes (IP = 5 ± 2.4 °C and CWI = 7.8 ± 3 °C – P < 0.01. For rewarming, after 25 minutes (IP = 20.8 ± 3.3 °C and CWI = 18.2 ± 2.7 °C – P < 0.04; after 45 minutes (IP = 24.5 ± 2.3 °C and IP = 22.1 ± 3.5 °C – P < 0.05; after 75 minutes (IP = 26.4 ± 2.2 °C and CWI = 24 ± 2.7 °C – P < 0.02. Conclusion After the 30-minute application, both IP and CWI produced the appropriate temperature; however the application of CWI produced the lowest temperature during rewarming.

  11. Invited: A Stability Study of Alkali Doped PBI Membranes for Alkaline Electrolyzer Cells

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Aili, David; Hansen, Martin Kalmar

    2014-01-01

    Alkaline fuel cells and electrolyzers are attracting increasing interest. This is to a large extent due to the broad selection of catalyst materials not based on resource limited and expensive noble metals. The first fuel cells in practical use were Francis Thomas Bacon’s based on an alkaline...

  12. Computational model for a high temperature electrolyzer coupled to a HTTR for efficient nuclear hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Daniel; Rojas, Leorlen; Rosales, Jesus; Castro, Landy; Gamez, Abel; Brayner, Carlos, E-mail: danielgonro@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Garcia, Lazaro; Garcia, Carlos; Torre, Raciel de la, E-mail: lgarcia@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba); Sanchez, Danny [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil)

    2015-07-01

    High temperature electrolysis process coupled to a very high temperature reactor (VHTR) is one of the most promising methods for hydrogen production using a nuclear reactor as the primary heat source. However there are not references in the scientific publications of a test facility that allow to evaluate the efficiency of the process and other physical parameters that has to be taken into consideration for its accurate application in the hydrogen economy as a massive production method. For this lack of experimental facilities, mathematical models are one of the most used tools to study this process and theirs flowsheets, in which the electrolyzer is the most important component because of its complexity and importance in the process. A computational fluid dynamic (CFD) model for the evaluation and optimization of the electrolyzer of a high temperature electrolysis hydrogen production process flowsheet was developed using ANSYS FLUENT®. Electrolyzer's operational and design parameters will be optimized in order to obtain the maximum hydrogen production and the higher efficiency in the module. This optimized model of the electrolyzer will be incorporated to a chemical process simulation (CPS) code to study the overall high temperature flowsheet coupled to a high temperature accelerator driven system (ADS) that offers advantages in the transmutation of the spent fuel. (author)

  13. Computational model for a high temperature electrolyzer coupled to a HTTR for efficient nuclear hydrogen production

    International Nuclear Information System (INIS)

    Gonzalez, Daniel; Rojas, Leorlen; Rosales, Jesus; Castro, Landy; Gamez, Abel; Brayner, Carlos; Garcia, Lazaro; Garcia, Carlos; Torre, Raciel de la; Sanchez, Danny

    2015-01-01

    High temperature electrolysis process coupled to a very high temperature reactor (VHTR) is one of the most promising methods for hydrogen production using a nuclear reactor as the primary heat source. However there are not references in the scientific publications of a test facility that allow to evaluate the efficiency of the process and other physical parameters that has to be taken into consideration for its accurate application in the hydrogen economy as a massive production method. For this lack of experimental facilities, mathematical models are one of the most used tools to study this process and theirs flowsheets, in which the electrolyzer is the most important component because of its complexity and importance in the process. A computational fluid dynamic (CFD) model for the evaluation and optimization of the electrolyzer of a high temperature electrolysis hydrogen production process flowsheet was developed using ANSYS FLUENT®. Electrolyzer's operational and design parameters will be optimized in order to obtain the maximum hydrogen production and the higher efficiency in the module. This optimized model of the electrolyzer will be incorporated to a chemical process simulation (CPS) code to study the overall high temperature flowsheet coupled to a high temperature accelerator driven system (ADS) that offers advantages in the transmutation of the spent fuel. (author)

  14. Hydrogen-oxygen proton-exchange membrane fuel cells and electrolyzers

    Science.gov (United States)

    Baldwin, R.; Pham, M.; Leonida, A.; Mcelroy, J.; Nalette, T.

    1990-01-01

    A flight experiment is planned for the validation, in a microgravity environment, of several ground-proven simplification features relating to SPE fuel cells and SPE electrolyzers. With a successful experiment, these features can be incorporated into equipment designs for specific extraterrestrial energy storage applications.

  15. OPTICAL CONSTANTS AND LAB SPECTRA OF WATER ICE V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Transmission spectra of amorphous and crystalline H2O-ice at temperatures from 20-150 K for a wavelength range from 1.11 to 2.63 microns. These spectra have not been...

  16. OPTICAL CONSTANTS AND LAB SPECTRA OF WATER ICE V1.1

    Data.gov (United States)

    National Aeronautics and Space Administration — Transmission spectra of amorphous and crystalline H2O-ice at temperatures from 20-150 K for a wavelength range from 1.11 to 2.63 microns. These spectra have not been...

  17. Development of antioxidative effect in ice cream with Kalakai (Stenochlaena palustris) water extract

    Science.gov (United States)

    Hadhiwaluyo, Kristania; Rahmawati, Della; Gunawan Puteri, Maria D. P. T.

    2017-11-01

    Kalakai (Stenochlaena. palustris) extract was used to develop the ice cream. The antioxidant activity of the extracts and its stability over process and storage were evaluated through various antioxidant assay including DPPH assay, Folin-Ciocalteau assay and aluminum chloride colorimetric method. In general, the leaves of S. palustris had a significantly higher antioxidant activity (p ice cream without affecting the sensory properties of the ice cream. In addition, the high phenolic and flavonoid content also suggest the more compounds that were capable to act as an antioxidant. The result of the stability test also suggested the ability low temperature storage and processing in maintaining the stability of the antioxidant activity of the extract (p > 0.05) over processing and storage. Thus, this strengthen the feasibility of S. palustris to be used as a potential functional food ingredient that is low cost and easily accessible with an antioxidant activity and safe iron content that is beneficial to increase the quality of food produced including in ice cream.

  18. Does Hot Water Freeze Faster Than Cold? Or Why Mpemba's Ice Cream Is a Discrepant Event

    Science.gov (United States)

    Palmer, Bill

    1993-01-01

    A discrepant event is a happening contrary to our current beliefs. Discrepant events are said to be useful in clarifying concepts. This is one of the interesting features of current theories of constructivism. The story of Mpemba's ice cream is quite well known, but it is the educational aspects of the experiment that are of interest in this…

  19. The Antartic Ice Borehole Probe

    Science.gov (United States)

    Behar, A.; Carsey, F.; Lane, A.; Engelhardt, H.

    2000-01-01

    The Antartic Ice Borehole Probe mission is a glaciological investigation, scheduled for November 2000-2001, that will place a probe in a hot-water drilled hole in the West Antartic ice sheet. The objectives of the probe are to observe ice-bed interactions with a downward looking camera, and ice inclusions and structure, including hypothesized ice accretion, with a side-looking camera.

  20. Ice Sheets & Ice Cores

    DEFF Research Database (Denmark)

    Mikkelsen, Troels Bøgeholm

    Since the discovery of the Ice Ages it has been evident that Earth’s climate is liable to undergo dramatic changes. The previous climatic period known as the Last Glacial saw large oscillations in the extent of ice sheets covering the Northern hemisphere. Understanding these oscillations known....... The first part concerns time series analysis of ice core data obtained from the Greenland Ice Sheet. We analyze parts of the time series where DO-events occur using the so-called transfer operator and compare the results with time series from a simple model capable of switching by either undergoing...

  1. The interaction of radio frequency electromagnetic fields with atmospheric water droplets and applications to aircraft ice prevention. Thesis

    Science.gov (United States)

    Hansman, R. J., Jr.

    1982-01-01

    The feasibility of computerized simulation of the physics of advanced microwave anti-icing systems, which preheat impinging supercooled water droplets prior to impact, was investigated. Theoretical and experimental work performed to create a physically realistic simulation is described. The behavior of the absorption cross section for melting ice particles was measured by a resonant cavity technique and found to agree with theoretical predictions. Values of the dielectric parameters of supercooled water were measured by a similar technique at lambda = 2.82 cm down to -17 C. The hydrodynamic behavior of accelerated water droplets was studied photograhically in a wind tunnel. Droplets were found to initially deform as oblate spheroids and to eventually become unstable and break up in Bessel function modes for large values of acceleration or droplet size. This confirms the theory as to the maximum stable droplet size in the atmosphere. A computer code which predicts droplet trajectories in an arbitrary flow field was written and confirmed experimentally. The results were consolidated into a simulation to study the heating by electromagnetic fields of droplets impinging onto an object such as an airfoil. It was determined that there is sufficient time to heat droplets prior to impact for typical parameter values. Design curves for such a system are presented.

  2. Cumulative and Synergistic Effects of Physical, Biological, and Acoustic Signals on Marine Mammal Habitat Use Physical Oceanography Component: Soundscapes Under Sea Ice: Can We Listen for Open Water?

    Science.gov (United States)

    2013-09-30

    Physical, Biological, and Acoustic Signals on Marine Mammal Habitat Use Physical Oceanography Component: Soundscapes Under Sea Ice: Can we listen for... Soundscapes Under Sea Ice: Can we listen for open water? 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...the source. These different sounds can be described as “ soundscapes ”, and graphically represented by comparing two or more features of the sound

  3. Fabrication of stable and durable superhydrophobic surface on copper substrates for oil-water separation and ice-over delay.

    Science.gov (United States)

    Guo, Jie; Yang, Fuchao; Guo, Zhiguang

    2016-03-15

    We report a simple and rapid method to fabricate superhydrophobic films on copper substrates via Fe(3+) etching and octadecanethiol (ODT) modification. The etching process can be as short as 5 min and the ODT treatment only takes several seconds. In addition, the whole process is quite flexible in reaction time. The superhydrophobicity of as-prepared surfaces is mechanically durable and chemically stable, which have great performance in oil-water separation and ice-over resistance. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. The Search for Eight Glacial Cycles of Deep-Water Temperatures and Global ice Volume From the Southern Hemisphere

    Science.gov (United States)

    Ferretti, P.; Elderfield, H.; Greaves, M.; McCave, N.

    2007-12-01

    It has been recently suggested "a substantial portion of the marine 100-ky cycle that has been object of so much attention over the past quarter of a century is, in reality, a deep-water temperature signal and not an ice volume signal" (Shackleton, 2000). There are currently few records available of deep-water temperature variations during the Pleistocene and most of our understanding is inferred from the oxygen isotopic composition (δ18O) of benthic foraminifera from deep-sea sediments. However, variations in benthic δ18O reflect some combination of local to regional changes in water mass properties (largely deep- water temperature) as well as global changes in seawater δ18O (δ18Osw) resulting from the growth and decay of continental ice. Recent studies suggest that benthic foraminiferal Mg/Ca may be useful in reconstructing deep-water temperature changes, but the application of this method to benthic species has been hampered by a number of unresolved issues, such as uncertainties related to the calibration for benthic Mg at the coldest temperatures. Here we present deep-sea Mg/Ca and δ18O records for the past eight glacial cycles in benthic foraminiferal ( Uvigerina spp.) calcite from a marine sediment core recovered in the mid Southern latitudes. Ocean Drilling Program Site 1123 was retrieved from Chatham Rise, east of New Zealand in the Southwest Pacific Ocean (3290 m water depth). This site lies under the Deep Western Boundary Current (DWBC) that flows into the Pacific Ocean, and is responsible for most of the deep water in that ocean; DWBC strength is directly related to processes occurring around Antarctica. Temperatures derived via pore fluid modeling of the last glacial maximum are available from Site 1123 and represent an important tool to constrain deep-water temperatures estimates using Mg/Ca. In selected time slices, we measured B/Ca ratios in Uvigerina in order to gain information on the deep-water carbonate saturation state and have data of Mg

  5. Semiempirical self-consistent polarization description of bulk water, the liquid-vapor interface, and cubic ice.

    Science.gov (United States)

    Murdachaew, Garold; Mundy, Christopher J; Schenter, Gregory K; Laino, Teodoro; Hutter, Jürg

    2011-06-16

    We have applied an efficient electronic structure approach, the semiempirical self-consistent polarization neglect of diatomic differential overlap (SCP-NDDO) method, previously parametrized to reproduce properties of water clusters by Chang, Schenter, and Garrett [ J. Chem. Phys. 2008 , 128 , 164111 ] and now implemented in the CP2K package, to model ambient liquid water at 300 K (both the bulk and the liquid-vapor interface) and cubic ice at 15 and 250 K. The SCP-NDDO potential retains its transferability and good performance across the full range of conditions encountered in the clusters and the bulk phases of water. In particular, we obtain good results for the density, radial distribution functions, enthalpy of vaporization, self-diffusion coefficient, molecular dipole moment distribution, and hydrogen bond populations, in comparison to experimental measurements. © 2011 American Chemical Society

  6. Effects of sea-ice light attenuation and CDOM absorption in the water below the Eurasian sector of central Arctic Ocean (> 880N)

    DEFF Research Database (Denmark)

    Lund-Hansen, Lars Chresten; Markager, Stiig; Hancke, Kasper

    2015-01-01

    This is a study of the optical, physical and biological parameters of sea ice and the water below it at stations (n=25) in the central (>88°N) Eurasian sector of the Arctic Ocean during the summer 2012 record low sea-ice minimum extent. Results show that photosynthetically active radiation (PAR......) transmittance of the ice was low (0.09) and apparently related to a high degree of backscattering by air-filled brine channels left by brine draining. The under-ice PAR was also low (8.4±4.5 SD µmol photons m−2 s−1) and partly related to the low transmittance. There were no significant differences in multi......-year and first-year PAR transmittances. In spite of this low under-ice PAR, only 3% of the transmitted PAR through the ice was absorbed by phytoplankton in the water. On average, chlorophyll-a concentrations were low (0.34±0.69 SD mg chl-a m−3) in the water compared to the high (a375=0.52 m−1) coloured dissolved...

  7. Radiation effects in ice: New results

    International Nuclear Information System (INIS)

    Baragiola, R.A.; Fama, M.; Loeffler, M.J.; Raut, U.; Shi, J.

    2008-01-01

    Studies of radiation effects in ice are motivated by intrinsic interest and by applications in astronomy. Here we report on new and recent results on radiation effects induced by energetic ions in ice: amorphization of crystalline ice, compaction of microporous amorphous ice, electrostatic charging and dielectric breakdown and correlated structural/chemical changes in the irradiation of water-ammonia ices

  8. Ice slurry applications

    Energy Technology Data Exchange (ETDEWEB)

    Kauffeld, M. [Karlsruhe University of Applied Sciences, Moltkestr. 30, 76133 Karlsruhe (Germany); Wang, M.J.; Goldstein, V. [Sunwell Technologies Inc., 180 Caster Avenue, Woodbridge, L4L 5Y (Canada); Kasza, K.E. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2010-12-15

    The role of secondary refrigerants is expected to grow as the focus on the reduction of greenhouse gas emissions increases. The effectiveness of secondary refrigerants can be improved when phase changing media are introduced in place of single-phase media. Operating at temperatures below the freezing point of water, ice slurry facilitates several efficiency improvements such as reductions in pumping energy consumption as well as lowering the required temperature difference in heat exchangers due to the beneficial thermo-physical properties of ice slurry. Research has shown that ice slurry can be engineered to have ideal ice particle characteristics so that it can be easily stored in tanks without agglomeration and then be extractable for pumping at very high ice fraction without plugging. In addition ice slurry can be used in many direct contact food and medical protective cooling applications. This paper provides an overview of the latest developments in ice slurry technology. (author)

  9. DETECTIONS OF WATER ICE, HYDROCARBONS, AND 3.3 μm PAH IN z ∼ 2 ULIRGs

    International Nuclear Information System (INIS)

    Sajina, Anna; Spoon, Henrik; Yan Lin; Imanishi, Masatoshi; Fadda, Dario; Elitzur, Moshe

    2009-01-01

    We present the first detections of the 3 μm water ice and 3.4 μm amorphous hydrocarbon (HAC) absorption features in z ∼ 2 ULIRGs. These are based on deep rest-frame 2-8 μm Spitzer Infrared Spectrograph spectra of 11 sources selected for their appreciable silicate absorption. The HAC-to-silicate ratio for our z ∼ 2 sources is typically higher by a factor of 2-5 than that observed in the Milky Way. This HAC 'excess' suggests compact nuclei with steep temperature gradients as opposed to predominantly host obscuration. Beside the above molecular absorption features, we detect the 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission feature in one of our sources with three more individual spectra showing evidence for it. Stacking analysis suggests that water ice, hydrocarbons, and PAH are likely present in the bulk of this sample even when not individually detected. The most unexpected result of our study is the lack of clear detections of the 4.67 μm CO gas absorption feature. Only three of the sources show tentative signs of this feature at significantly lower levels than has been observed in local ULIRGs. Overall we find that the closest local analogs to our sources, in terms of 3-4 μm color, HAC-to-silicate and ice-to-silicate ratios, as well as low PAH equivalent widths, are sources dominated by deeply obscured nuclei. Such sources form only a small fraction of ULIRGs locally and are commonly believed to be dominated by buried active galactic nuclei (AGNs). Our sample suggests that, in an absolute number, such buried AGNs are at least an order of magnitude more common at z ∼ 2 than today. The presence of PAH suggests that significant levels of star formation are present even if the obscured AGNs typically dominate the power budget.

  10. The photoexcitation of crystalline ice and amorphous solid water: A molecular dynamics study of outcomes at 11 K and 125 K

    Energy Technology Data Exchange (ETDEWEB)

    Crouse, J.; Loock, H.-P., E-mail: hploock@chem.queensu.ca; Cann, N. M., E-mail: ncann@chem.queensu.ca [Department of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6 (Canada)

    2015-07-21

    Photoexcitation of crystalline ice Ih and amorphous solid water at 7-9 eV is examined using molecular dynamics simulations and a fully flexible water model. The probabilities of photofragment desorption, trapping, and recombination are examined for crystalline ice at 11 K and at 125 K and for amorphous solid water at 11 K. For 11 K crystalline ice, a fully rigid water model is also employed for comparison. The kinetic energy of desorbed H atoms and the distance travelled by trapped fragments are correlated to the location and the local environment of the photoexcited water molecule. In all cases, H atom desorption is found to be the most likely outcome in the top bilayer while trapping of all photofragments is most probable deeper in the solid where the likelihood for recombination of the fragments into H{sub 2}O molecules also rises. Trajectory analysis indicates that the local hydrogen bonding network in amorphous solid water is more easily distorted by a photodissociation event compared to crystalline ice. Also, simulations indicate that desorption of OH radicals and H{sub 2}O molecules are more probable in amorphous solid water. The kinetic energy distributions for desorbed H atoms show a peak at high energy in crystalline ice, arising from photoexcited water molecules in the top monolayer. This peak is less pronounced in amorphous solid water. H atoms that are trapped may be displaced by up to ∼10 water cages, but migrate on average 3 water cages. Trapped OH fragments tend to stay near the original solvent cage.

  11. Ice, Ice, Baby!

    Science.gov (United States)

    Hamilton, C.

    2008-12-01

    The Center for Remote Sensing of Ice Sheets (CReSIS) has developed an outreach program based on hands-on activities called "Ice, Ice, Baby". These lessons are designed to teach the science principles of displacement, forces of motion, density, and states of matter. These properties are easily taught through the interesting topics of glaciers, icebergs, and sea level rise in K-8 classrooms. The activities are fun, engaging, and simple enough to be used at science fairs and family science nights. Students who have participated in "Ice, Ice, Baby" have successfully taught these to adults and students at informal events. The lessons are based on education standards which are available on our website www.cresis.ku.edu. This presentation will provide information on the activities, survey results from teachers who have used the material, and other suggested material that can be used before and after the activities.

  12. AERATION OF THE ICE-COVERED WATER POOLS USING THE WAVE FLOW AERATOR

    Directory of Open Access Journals (Sweden)

    Solomin E.E

    2013-12-01

    Full Text Available This article describes the technical advantages and economic benefits of the ice-covered pool aeration plants consuming power from renewable energy sources. We made a comparative evaluation of the wave flow-aeration method and other methods of pool aeration. We showed the indexes and the characteristics of the wave flow-maker for aeration of ice-covered pools on the territory of Russia. We also made calculations of the economic benefits of aeration plants using the devices converting renewable energy. The project can be scaled and extended to the territory of the CIS, Europe, USA and Canada in the changing climate conditions and the variety of feed reservoirs around the world.

  13. Monitoring ice nucleation in pure and salty water via high-speed imaging and computer simulations

    Czech Academy of Sciences Publication Activity Database

    Bauerecker, S.; Ulbig, P.; Buch, V.; Vrbka, Luboš; Jungwirth, Pavel

    2008-01-01

    Roč. 112, č. 20 (2008), s. 7631-7636 ISSN 1932-7447 R&D Projects: GA MŠk LC512; GA ČR(CZ) GD203/05/H001 Grant - others:DFG(DE) 529278 Institutional research plan: CEZ:AV0Z40550506 Keywords : ice freezing * high speed imaging * molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.396, year: 2008

  14. Economics of liquid hydrogen from water electrolysis

    Science.gov (United States)

    Lin, F. N.; Moore, W. I.; Walker, S. W.

    1985-01-01

    An economical model for preliminary analysis of LH2 cost from water electrolysis is presented. The model is based on data from vendors and open literature, and is suitable for computer analysis of different scenarios for 'directional' purposes. Cost data associated with a production rate of 10,886 kg/day are presented. With minimum modification, the model can also be used to predict LH2 cost from any electrolyzer once the electrolyzer's cost data are available.

  15. Water Vapor, Temperature, and Ice Particles in Polar Mesosphere as Measured by SABER/TIMED and OSIRIS/Odin Instruments

    Science.gov (United States)

    Feofilov, A. G.; Petelina, S. V.; Kutepov, A. A.; Pesnell, W. D.; Goldberg, R. A.

    2009-01-01

    Although many new details on the properties of mesospheric ice particles that farm Polar Mesospheric Clouds (PMCs) and also cause polar mesospheric summer echoes have been recently revealed, certain aspects of mesospheric ice microphysics and dynamics still remain open. The detailed relation between PMC parameters and properties of their environment, as well as interseasonal and interhemispheric differences and trends in PMC properties that are possibly related to global change, are among those open questions. In this work, mesospheric temperature and water vapor concentration measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite are used to study the properties of PMCs with respect to the surrounding atmosphere. The cloud parameters, namely location, brightness, and altitude, are obtained from the observations made by the Optical Spectrograph and Infrared Imager System (OSIRIS) on the Odin satellite. About a thousand of simultaneous common volume measurements made by SABER and OSIRIS in both hemispheres from 2002 until 2008 are used. The correlation between PMC brightness (and occurrence rate) and temperatures at PMC altitudes and at the mesopause is analysed. The relation between PMC parameters, frost point temperature, and gaseous water vapor content in and below the cloud is also discussed. Interseasonal and interhemispheric differences and trends in the above parameters, as well as in PMC peak altitudes and mesopause altitudes are evaluated.

  16. 199 bacteriological quality of water used for ice making in some

    African Journals Online (AJOL)

    DR. AMINU

    2010-06-01

    Jun 1, 2010 ... from water related diseases like typhoid and para typhoid fevers, cholera bacillary dysentery and gastroenteritis. Water borne or related pathogens including bacteria are spread in water either through human ingestion of contaminated water or because water provides the habitat for intermediate host.

  17. Laurentide Ice-Sheet Meltwater Sources to the Gulf of Mexico During the Last Deglaciation: Assessing Data Reconstructions Using Water Isotope Enabled Simulations

    Science.gov (United States)

    Vetter, L.; LeGrande, A. N.; Ullman, D. J.; Carlson, A. E.

    2017-12-01

    Sediment cores from the Gulf of Mexico show evidence of meltwater derived from the Laurentide Ice Sheet during the last deglaciation. Recent studies using geochemical measurements of individual foraminifera suggest changes in the oxygen isotopic composition of the meltwater as deglaciation proceeded. Here we use the water isotope enabled climate model simulations (NASA GISS ModelE-R) to investigate potential sources of meltwater within the ice sheet. We find that initial melting of the ice sheet from the southern margin contributed an oxygen isotope value reflecting a low-elevation, local precipitation source. As deglacial melting proceeded, meltwater delivered to the Gulf of Mexico had a more negative oxygen isotopic value, which the climate model simulates as being sourced from the high-elevation, high-latitude interior of the ice sheet. This study demonstrates the utility of combining stable isotope analyses with climate model simulations to investigate past changes in the hydrologic cycle.

  18. Improved regional sea-level estimates from Ice Sheets, Glaciers and land water storage using GRACE time series and other data

    Science.gov (United States)

    He, Z.; Velicogna, I.; Hsu, C. W.; Rignot, E. J.; Mouginot, J.; Scheuchl, B.; Fettweis, X.; van den Broeke, M. R.

    2017-12-01

    Changes in ice sheets, glaciers and ice caps (GIC) and land water mass cause regional sea level variations that differ significantly from a uniform re-distribution of mass over the ocean, with a decrease in sea level compared to the global mean sea level contribution (GMSL) near the sources of mass added to the ocean and an increase up to 30% larger than the GMSL in the far field. The corresponding sea level fingerprints (SLF) are difficult to separate from ocean dynamics on short time and spatial scales but as ice melt continues, the SLF signal will become increasingly dominant in the pattern of regional sea level rise. It has been anticipated that it will be another few decades before the land ice SLF could be identified in the pattern of regional sea level rise. Here, we combine 40 years of observations of ice sheet mass balance for Antarctica (1975-present) and Greenland (1978-present), along with surface mass balance reconstructions of glacier and ice caps mass balance (GIC) from 1970s to present to determine the contribution to the SLF from melting land ice (MAR and RACMO). We compare the results with observations from GRACE for the time period 2002 to present for evaluation of our approach. Land hydrology is constrained by GRACE data for the period 2002-present and by the GLDAS-NOAH land hydrology model for the longer time period. Over the long time period, we find that the contribution from land ice dominates. We quantify the contribution to the total SLF from Greenland and Antarctica in various parts of the world over the past 40 years. More important, we compare the cumulative signal from SLF with tide gauge records around the world, corrected for earth dynamics, to determine whether the land ice SLF can be detected in that record. Early results will be reported at the meeting. This work was performed at UC Irvine and at Caltech's Jet Propulsion Laboratory under a contract with NASA's Cryospheric Science Program.

  19. Numerical implementation and oceanographic application of the thermodynamic potentials of liquid water, water vapour, ice, seawater and humid air – Part 1: Background and equations

    Directory of Open Access Journals (Sweden)

    R. Feistel

    2010-07-01

    Full Text Available A new seawater standard referred to as the International Thermodynamic Equation of Seawater 2010 (TEOS-10 was adopted in June 2009 by UNESCO/IOC on its 25th General Assembly in Paris, as recommended by the SCOR/IAPSO Working Group 127 (WG127 on Thermodynamics and Equation of State of Seawater. To support the adoption process, WG127 has developed a comprehensive source code library for the thermodynamic properties of liquid water, water vapour, ice, seawater and humid air, referred to as the Sea-Ice-Air (SIA library. Here we present the background information and equations required for the determination of the properties of single phases and components as well as of phase transitions and composite systems as implemented in the library. All results are based on rigorous mathematical methods applied to the Primary Standards of the constituents, formulated as empirical thermodynamic potential functions and, except for humid air, endorsed as Releases of the International Association for the Properties of Water and Steam (IAPWS. Details of the implementation in the TEOS-10 SIA library are given in a companion paper.

  20. High-resolution continuous flow analysis setup for water isotopic measurement from ice cores using laser spectroscopy

    Science.gov (United States)

    Emanuelsson, B. D.; Baisden, W. T.; Bertler, N. A. N.; Keller, E. D.; Gkinis, V.

    2014-12-01

    Here we present an experimental setup for water stable isotopes (δ18O and δD) continuous flow measurements. It is the first continuous flow laser spectroscopy system that is using Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS; analyzer manufactured by Los Gatos Research - LGR) in combination with an evaporation unit to continuously analyze sample from an ice core. A Water Vapor Isotopic Standard Source (WVISS) calibration unit, manufactured by LGR, was modified to: (1) increase the temporal resolution by reducing the response time (2) enable measurements on several water standards, and (3) to reduce the influence from memory effects. While this setup was designed for the Continuous Flow Analysis (CFA) of ice cores, it can also continuously analyze other liquid or vapor sources. The modified setup provides a shorter response time (~54 and 18 s for 2013 and 2014 setup, respectively) compared to the original WVISS unit (~62 s), which is an improvement in measurement resolution. Another improvement compared to the original WVISS is that the modified setup has a reduced memory effect. Stability tests comparing the modified WVISS and WVISS setups were performed and Allan deviations (σAllan) were calculated to determine precision at different averaging times. For the 2013 modified setup the precision after integration times of 103 s are 0.060 and 0.070‰ for δ18O and δD, respectively. For the WVISS setup the corresponding σAllan values are 0.030, 0.060 and 0.043‰ for δ18O, δD and δ17O, respectively. For the WVISS setup the precision is 0.035, 0.070 and 0.042‰ after 103 s for δ18O, δD and δ17O, respectively. Both the modified setups and WVISS setup are influenced by instrumental drift with δ18O being more drift sensitive than δD. The σAllan values for δ18O of 0.30 and 0.18‰ for the modified (2013) and WVISS setup, respectively after averaging times of 104 s (2.78 h). The Isotopic Water Analyzer (IWA)-modified WVISS setup used during the

  1. High-resolution continuous-flow analysis setup for water isotopic measurement from ice cores using laser spectroscopy

    Science.gov (United States)

    Emanuelsson, B. D.; Baisden, W. T.; Bertler, N. A. N.; Keller, E. D.; Gkinis, V.

    2015-07-01

    Here we present an experimental setup for water stable isotope (δ18O and δD) continuous-flow measurements and provide metrics defining the performance of the setup during a major ice core measurement campaign (Roosevelt Island Climate Evolution; RICE). We also use the metrics to compare alternate systems. Our setup is the first continuous-flow laser spectroscopy system that is using off-axis integrated cavity output spectroscopy (OA-ICOS; analyzer manufactured by Los Gatos Research, LGR) in combination with an evaporation unit to continuously analyze water samples from an ice core. A Water Vapor Isotope Standard Source (WVISS) calibration unit, manufactured by LGR, was modified to (1) enable measurements on several water standards, (2) increase the temporal resolution by reducing the response time and (3) reduce the influence from memory effects. While this setup was designed for the continuous-flow analysis (CFA) of ice cores, it can also continuously analyze other liquid or vapor sources. The custom setups provide a shorter response time (~ 54 and 18 s for 2013 and 2014 setup, respectively) compared to the original WVISS unit (~ 62 s), which is an improvement in measurement resolution. Another improvement compared to the original WVISS is that the custom setups have a reduced memory effect. Stability tests comparing the custom and WVISS setups were performed and Allan deviations (σAllan) were calculated to determine precision at different averaging times. For the custom 2013 setup the precision after integration times of 103 s is 0.060 and 0.070 ‰ for δ18O and δD, respectively. The corresponding σAllan values for the custom 2014 setup are 0.030, 0.060 and 0.043 ‰ for δ18O, δD and δ17O, respectively. For the WVISS setup the precision is 0.035, 0.070 and 0.042 ‰ after 103 s for δ18O, δD and δ17O, respectively. Both the custom setups and WVISS setup are influenced by instrumental drift with δ18O being more drift sensitive than δD. The

  2. Overcoming the Instability of Nanoparticle-Based Catalyst Films in Alkaline Electrolyzers by using Self-Assembling and Self-Healing Films.

    Science.gov (United States)

    Barwe, Stefan; Masa, Justus; Andronescu, Corina; Mei, Bastian; Schuhmann, Wolfgang; Ventosa, Edgar

    2017-07-10

    Engineering stable electrodes using highly active catalyst nanopowders for electrochemical water splitting remains a challenge. We report an innovative and general approach for attaining highly stable catalyst films with self-healing capability based on the in situ self-assembly of catalyst particles during electrolysis. The catalyst particles are added to the electrolyte forming a suspension that is pumped through the electrolyzer. Particles with negatively charged surfaces stick onto the anode, while particles with positively charged surfaces stick to the cathode. The self-assembled catalyst films have self-healing properties as long as sufficient catalyst particles are present in the electrolyte. The proof-of-concept was demonstrated in a non-zero gap alkaline electrolyzer using NiFe-LDH and Ni x B catalyst nanopowders for anode and cathode, respectively. Steady cell voltages were maintained for at least three weeks during continuous electrolysis at 50-100 mA cm -2 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Micrometer-sized Water Ice Particles for Planetary Science Experiments: Influence of Surface Structure on Collisional Properties

    Science.gov (United States)

    Gaertner, Sabrina; Gundlach, Bastian; Headen, Thomas F.; Ratte, Judy; Oesert, Joachim; Gorb, Stanislav N.; Youngs, Tristan G. A.; Bowron, Daniel T.; Blum, Jürgen; Fraser, Helen

    2018-06-01

    Models and observations suggest that particle aggregation at and beyond the snowline is aided by water ice. As icy particles play such a crucial role in the earliest stages of planet formation, many laboratory studies have exploited their collisional properties across a wide range of parameters (particle size, impact velocity, temperature T, and pressure P).However, not all of these parameters have always been varied systematically, leading to apparently contradictory results on collision outcomes. Previous experiments only agreed that a temperature dependence set in above ≈210 K. Open questions remain as to what extent the structural properties of the particles themselves dictate collision outcomes. The P–T gradients in protoplanetary disks mean that the ices are constantly processed, undergoing phase changes between different solid phases and the gas phase. To understand how effectively collision experiments reproduce protoplanetary disk conditions, environmental impacts on particle structure need to be investigated.We characterized the bulk and surface structure of icy particles used in collision experiments, exploiting the unique capabilities of the NIMROD neutron scattering instrument. Varying temperature at a constant pressure of around 30 mbar, we studied structural alterations to determine which of the observed properties matches the temperature dependencies observed in collisional behaviour.Our icy grains are formed under liquid nitrogen and heated from 103 to 247 K. As a result, they undergo changes in the crystalline ice-phase, sublimation, sintering and surface pre-melting. An increase in the thickness of the diffuse surface layer from ≈10 to ≈30 Å (≈2.5 to 12 bilayers) suggests increased molecular mobility at temperatures above ≈210 K.Because none of the other changes ties in with the temperature trends in collisional outcomes, we conclude that the diffuse interface plays a key role in collision experiments at these temperatures

  4. Fluorescent pseudomonads isolated from Hebridean cloud and rain water produce biosurfactants but do not cause ice nucleation

    Science.gov (United States)

    Ahern, H. E.; Walsh, K. A.; Hill, T. C. J.; Moffett, B. F.

    2007-02-01

    Microorganisms were discovered in clouds over 100 years ago but information on bacterial community structure and function is limited. Clouds may not only be a niche within which bacteria could thrive but they might also influence dynamic processes using ice nucleating and cloud condensing abilities. Cloud and rain samples were collected from two mountains in the Outer Hebrides, NW Scotland, UK. Community composition was determined using a combination of amplified 16S ribosomal DNA restriction analysis and sequencing. 256 clones yielded 100 operational taxonomic units (OTUs) of which half were related to bacteria from terrestrial psychrophilic environments. Cloud samples were dominated by a mixture of fluorescent Pseudomonas spp., some of which have been reported to be ice nucleators. It was therefore possible that these bacteria were using the ice nucleation (IN) gene to trigger the Bergeron-Findeisen process of raindrop formation as a mechanism for dispersal. In this study the IN gene was not detected in any of the isolates using both polymerase chain reaction (PCR) and differential scanning calorimetry (DSC). Instead 55% of the total isolates from both cloud and rain samples displayed significant biosurfactant activity when analyzed using the drop-collapse technique. All isolates were characterised as fluorescent pseudomonads. Surfactants have been found to be very important in lowering atmospheric critical supersaturations required for the activation of aerosols into cloud condensation nuclei (CCN). It is also known that surfactants influence cloud droplet size and increase cloud lifetime and albedo. Some bacteria are known to act as CCN and so it is conceivable that these fluorescent pseudomonads are using surfactants to facilitate their activation from aerosols into CCN. This would allow water scavenging,~countering desiccation, and assist in their widespread dispersal.

  5. Reactions of hot nitrogen in water-ice at 77 K

    International Nuclear Information System (INIS)

    Roessler, K.; Schurwanz, K.

    1985-04-01

    The reactions of hot nitrogen atoms were studied in H 2 O-ice at 77 K. The nitrogen atoms were generated via the nuclear process 16 O(p,α) 13 N with 20 MeV protons from a cyclotron and by implantation of 250 keV 14 N + ions. The formation of chemical compounds of 13 N was studied over a wide dose range of the energy deposited by the protons from Dsup(*)=10 -2 to 26 eV per target molecule. The 13 N-labeled products and their yields as depending on the dose were determined via high performance liquid chromatography (HPLC) and radio-gaschromatography (GC). The reactions of implanted 14 N + ions were studied in H 2 O-ice at 6 K. The analysis of the products was achieved by optical low-temperature spectroscopy in the near UV, visible and infrared spectral regions. Primary (original hot) products of 13 N were: 13 NH 4 + with a radiochemical yield of 51%, 13 NO 2 - (37%), and 13 NO 3 - (9%) as detected after irradiation with the lowest proton dose applied of Dsup(*)=10 -2 eV. With increasing dose the 13 NH 4 + -yield rose to a broad maximum at 95%. Correspondingly the yields of nitrite and nitrate decreased. Applications of the studies are the preparation of 13 N-labeled precursor compounds for the fast synthesis of 13 N-radiopharmaceuticals and the laboratory simulations of chemical processes in the interplanetary and interstellar ice bodies. The ion implantation studies gave first information on the hot formation of nitrogen-oxygen compounds. NH-compounds could not be found in the spectra. This reflects the 13 N-product distribution at high doses in the nuclear recoil experiments. (orig./RB) [de

  6. Turning into Ice

    Science.gov (United States)

    Pietsch, Renée B.; Hanlon, Regina; Bohland, Cynthia; Schmale, David G., III

    2016-01-01

    This article describes an interdisciplinary unit in which students explore biological "ice nucleation"--by particles that cause water to freeze at temperatures above -38°C--through the lens of the microbial ice nucleator "Pseudomonas syringae." Such This activity, which aligns with the "Next Generation Science…

  7. Control and Analysis for a Self-Excited Induction Generator for Wind Turbine and Electrolyzer Applications

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Na, Woonki [California State University, Fresno; Leighty, Bill [The Leighty Foundation; Kim, Jonghoon [Chungnam National University

    2017-12-14

    Self-Excited Induction Generation(SEIG) is very rugged, simple, lightweight, and it is easy and inexpensive to implement, very simple to control, and requires a very little maintenance. In this variable-speed operation, the SEIG needs a power electronics interface to convert from the variable frequency output voltage of the generator to a DC output voltage for battery or other DC applications. In our study, a SEIG is connected to the power electronics interface such as diode rectifier and DC/DC converter and then an electrolyzer is connected as a final DC load for fuel cell applications. An equivalent circuit model for an electrolyzer is utilized for our application. The control and analysis for the proposed system is carried out by using PSCAD and MATLAB software. This study would be useful for designing and control analysis of power interface circuits for SEIG for a variable speed wind turbine generation with fuel cell applications before the actual implementation.

  8. Ice nucleation activity of silicates and aluminosilicates in pure water and aqueous solutions - Part 1: The K-feldspar microcline

    Science.gov (United States)

    Kumar, Anand; Marcolli, Claudia; Luo, Beiping; Peter, Thomas

    2018-05-01

    Potassium-containing feldspars (K-feldspars) have been considered as key mineral dusts for ice nucleation (IN) in mixed-phase clouds. To investigate the effect of solutes on their IN efficiency, we performed immersion freezing experiments with the K-feldspar microcline, which is highly IN active. Freezing of emulsified droplets with microcline suspended in aqueous solutions of NH3, (NH4)2SO4, NH4HSO4, NH4NO3, NH4Cl, Na2SO4, H2SO4, K2SO4 and KCl, with solute concentrations corresponding to water activities aw = 0.9-1.0, were investigated by means of a differential scanning calorimeter (DSC). The measured heterogeneous IN onset temperatures, Thet(aw), deviate strongly from ThetΔawhet(aw), the values calculated from the water-activity-based approach (where ThetΔawhet(aw) = Tmelt(aw + Δawhet) with a constant offset Δawhet with respect to the ice melting point curve). Surprisingly, for very dilute solutions of NH3 and NH4+ salts (molalities ≲1 mol kg-1 corresponding to aw ≳ 0.96), we find IN temperatures raised by up to 4.5 K above the onset freezing temperature of microcline in pure water (Thet(aw = 1)) and 5.5 K above ThetΔawhet(aw), revealing NH3 and NH4+ to significantly enhance the IN of the microcline surface. Conversely, more concentrated NH3 and NH4+ solutions show a depression of the onset temperature below ThetΔawhet(aw) by as much as 13.5 K caused by a decline in IN ability accompanied with a reduction in the volume fraction of water frozen heterogeneously. All salt solutions not containing NH4+ as cation exhibit nucleation temperatures Thet(aw) NH4+). However, the presence of a similar increase in IN efficiency in dilute ammonia solutions indicates that the cation exchange cannot explain the increase in IN temperatures. Instead, we hypothesize that NH3 molecules hydrogen bonded on the microcline surface form an ice-like overlayer, which provides hydrogen bonding favorable for ice to nucleate on, thus enhancing both the freezing temperatures and the

  9. An integrated approach to the remote sensing of floating ice

    Science.gov (United States)

    Campbell, W. J.; Ramseier, R. O.; Weeks, W. F.; Gloersen, P.

    1976-01-01

    Review article on remote sensing applications to glaciology. Ice parameters sensed include: ice cover vs open water, ice thickness, distribution and morphology of ice formations, vertical resolution of ice thickness, ice salinity (percolation and drainage of brine; flushing of ice body with fresh water), first-year ice and multiyear ice, ice growth rate and surface heat flux, divergence of ice packs, snow cover masking ice, behavior of ice shelves, icebergs, lake ice and river ice; time changes. Sensing techniques discussed include: satellite photographic surveys, thermal IR, passive and active microwave studies, microwave radiometry, microwave scatterometry, side-looking radar, and synthetic aperture radar. Remote sensing of large aquatic mammals and operational ice forecasting are also discussed.

  10. Sensation of Cold during the Ice Water Test Corresponds to the Perception of Pain during Botulinum Toxin Bladder Wall Injections.

    Science.gov (United States)

    Reitz, André; Hüsch, Tanja; Doggweiler, Regula; Buse, Stephan; Haferkamp, Axel

    2018-01-01

    To investigate the association of bladder cold sensation (BCS) during the ice water test (IWT) and pain perception when botulinum toxin injections (BTI) are administered into the bladder wall. In 86 patients with idiopathic overactive bladder, the BCS during the IWT was investigated. Patients were divided into 2 groups: with and without BCS. During subsequent administration of BTI, the number of perceived and painful injections as well as the pain levels on a 0-100 pain scale were compared in both groups using Student t test. Thirty-five patients reported a BCS, while 51 did not. After 10 BTI, the mean number of perceived injections was 7.9 in patients with and 2.4 in patients without BCS (p sensation (p perceptions of cold and pain in the urinary bladder may use similar receptors and neuronal pathways. © 2018 S. Karger AG, Basel.

  11. Synergistic multi-sensor and multi-frequency retrieval of cloud ice water path constrained by CloudSat collocations

    International Nuclear Information System (INIS)

    Islam, Tanvir; Srivastava, Prashant K.

    2015-01-01

    The cloud ice water path (IWP) is one of the major parameters that have a strong influence on earth's radiation budget. Onboard satellite sensors are recognized as valuable tools to measure the IWP in a global scale. Albeit, active sensors such as the Cloud Profiling Radar (CPR) onboard the CloudSat satellite has better capability to measure the ice water content profile, thus, its vertical integral, IWP, than any passive microwave (MW) or infrared (IR) sensors. In this study, we investigate the retrieval of IWP from MW and IR sensors, including AMSU-A, MHS, and HIRS instruments on-board the N19 satellite, such that the retrieval is consistent with the CloudSat IWP estimates. This is achieved through the collocations between the passive satellite measurements and CloudSat scenes. Potential benefit of synergistic multi-sensor multi-frequency retrieval is investigated. Two modeling approaches are explored for the IWP retrieval – generalized linear model (GLM) and neural network (NN). The investigation has been carried out over both ocean and land surface types. The MW/IR synergy is found to be retrieved more accurate IWP than the individual AMSU-A, MHS, or HIRS measurements. Both GLM and NN approaches have been able to exploit the synergistic retrievals. - Highlights: • MW/IR synergy is investigated for IWP retrieval. • The IWP retrieval is modeled using CloudSat collocations. • Two modeling approaches are explored – GLM and ANN. • MW/IR synergy performs better than the MW or IR only retrieval

  12. Suppression of the water ice and snow albedo feedback on planets orbiting red dwarf stars and the subsequent widening of the habitable zone.

    Science.gov (United States)

    Joshi, Manoj M; Haberle, Robert M

    2012-01-01

    M stars comprise 80% of main sequence stars, so their planetary systems provide the best chance for finding habitable planets, that is, those with surface liquid water. We have modeled the broadband albedo or reflectivity of water ice and snow for simulated planetary surfaces orbiting two observed red dwarf stars (or M stars), using spectrally resolved data of Earth's cryosphere. The gradual reduction of the albedos of snow and ice at wavelengths greater than 1 μm, combined with M stars emitting a significant fraction of their radiation at these same longer wavelengths, means that the albedos of ice and snow on planets orbiting M stars are much lower than their values on Earth. Our results imply that the ice/snow albedo climate feedback is significantly weaker for planets orbiting M stars than for planets orbiting G-type stars such as the Sun. In addition, planets with significant ice and snow cover will have significantly higher surface temperatures for a given stellar flux if the spectral variation of cryospheric albedo is considered, which in turn implies that the outer edge of the habitable zone around M stars may be 10-30% farther away from the parent star than previously thought.

  13. Template Directed Oligomer Ligation in Eutectic Phases in Water-Ice

    DEFF Research Database (Denmark)

    Dörr, Mark; Löffler, Philipp M. G.; Wieczorek, Rafal

    2011-01-01

    achieved, if small, activated, oligonucleotides are ligated on a template. A template directed ligation can lead to autocatalytic or cross- catalytic replication and thus maintain a certain pool of catalyitc species. Important for these processes is a destabilization of the formed douplex....../multiplex to overcome product inhibition. The latest results of our template directed ligation experiments in the eutectic ice phase are presented. Different activation strategies are compared and an outlook towards applications in molecular evolution and artifical cell systems (« protocells ») will be given. Figure 1....... (a) Reaction scheme of the condensation reaction of two oligoribonucleotides : The leaving group in this example is imidazole. (b) Illustration of a possible spatial arrangement of a template (15nt) directed ligation. The 7-mer is activated with imidazole at the 5' phosphate (apical moiety...

  14. Modeling of Waves Propagating in Water with a Crushed Ice Layer on the Free Surface

    Science.gov (United States)

    Szmidt, Kazimierz

    2017-12-01

    A transformation of gravitational waves in fluid of constant depth with a crushed ice layer floating on the free fluid surface is considered. The propagating waves undergo a slight damping along their path of propagation. The main goal of the study is to construct an approximate descriptive model of this phenomenon.With regard to small displacements of the free surface, a viscous type model of damping is considered, which corresponds to a continuous distribution of dash-pots at the free surface of the fluid. A constant parameter of the dampers is assumed in advance as known parameter of damping. This parameter may be obtained by means of experiments in a laboratory flume.

  15. ARKTOS amphibious oil spill response craft for mixed ice/water conditions

    Energy Technology Data Exchange (ETDEWEB)

    Seligman, Bruce H.J.W. [ARKTOS International S.A., Tavannes (Switzerland)], email: bruce.seligman@arktoscraft.com; Hall, T.A. [Hall Marine Design Ltd., Vancouver B.C. (Canada)], email: thallhmd@telus.net

    2010-07-01

    The oil spill which occurred recently in the Gulf of Mexico highlighted the lack of efficient oil spill clean-up equipment for an offshore environment. With the increase in industrial operations in the Arctic Seas it is of high importance to develop an efficient oil spill response as the absence of reliable oil spill contingency plans will not be tolerated in such environmentally sensitive areas. The aim of this paper is to present the use of the ARKTOS amphibious craft for cleaning up an oil spill in the Arctic. This craft is usually used for logistical services and evacuation purposes; its use for clean-up purposes has been under study since 2000. This study showed that the ARKTOS craft could be an efficient means for oil spill clean-up in the Arctic because of its proven ice capable amphibious platforms and its hydraulic power; however oil collection trials should be performed to validate it.

  16. ARKTOS amphibious oil spill response craft for mixed ice/water conditions

    International Nuclear Information System (INIS)

    Seligman, Bruce H.J.W.; Hall, T.A.

    2010-01-01

    The oil spill which occurred recently in the Gulf of Mexico highlighted the lack of efficient oil spill clean-up equipment for an offshore environment. With the increase in industrial operations in the Arctic Seas it is of high importance to develop an efficient oil spill response as the absence of reliable oil spill contingency plans will not be tolerated in such environmentally sensitive areas. The aim of this paper is to present the use of the ARKTOS amphibious craft for cleaning up an oil spill in the Arctic. This craft is usually used for logistical services and evacuation purposes; its use for clean-up purposes has been under study since 2000. This study showed that the ARKTOS craft could be an efficient means for oil spill clean-up in the Arctic because of its proven ice capable amphibious platforms and its hydraulic power; however oil collection trials should be performed to validate it.

  17. Premelting, fluctuations, and coarse-graining of water-ice interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Limmer, David T., E-mail: dlimmer@princeton.edu [Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08540 (United States); Chandler, David [Department of Chemistry, University of California, Berkeley, California 94609 (United States)

    2014-11-14

    Using statistical field theory supplemented with molecular dynamics simulations, we consider premelting on the surface of ice as a generic consequence of broken hydrogen bonds at the boundary between the condensed and gaseous phases. A procedure for coarse-graining molecular configurations onto a continuous scalar order parameter field is discussed, which provides a convenient representation of the interface between locally crystal-like and locally liquid-like regions. A number of interfacial properties are straightforwardly evaluated using this procedure such as the average premelting thickness and surface tension. The temperature and system size dependence of the premelting layer thickness calculated in this way confirms the characteristic logarithmic growth expected for the scalar field theory that the system is mapped onto through coarse-graining, though remains finite due to long-ranged interactions. Finally, from explicit simulations the existence of a premelting layer is shown to be insensitive to bulk lattice geometry, exposed crystal face, and curvature.

  18. Premelting, fluctuations, and coarse-graining of water-ice interfaces

    Science.gov (United States)

    Limmer, David T.; Chandler, David

    2014-11-01

    Using statistical field theory supplemented with molecular dynamics simulations, we consider premelting on the surface of ice as a generic consequence of broken hydrogen bonds at the boundary between the condensed and gaseous phases. A procedure for coarse-graining molecular configurations onto a continuous scalar order parameter field is discussed, which provides a convenient representation of the interface between locally crystal-like and locally liquid-like regions. A number of interfacial properties are straightforwardly evaluated using this procedure such as the average premelting thickness and surface tension. The temperature and system size dependence of the premelting layer thickness calculated in this way confirms the characteristic logarithmic growth expected for the scalar field theory that the system is mapped onto through coarse-graining, though remains finite due to long-ranged interactions. Finally, from explicit simulations the existence of a premelting layer is shown to be insensitive to bulk lattice geometry, exposed crystal face, and curvature.

  19. Premelting, fluctuations, and coarse-graining of water-ice interfaces

    International Nuclear Information System (INIS)

    Limmer, David T.; Chandler, David

    2014-01-01

    Using statistical field theory supplemented with molecular dynamics simulations, we consider premelting on the surface of ice as a generic consequence of broken hydrogen bonds at the boundary between the condensed and gaseous phases. A procedure for coarse-graining molecular configurations onto a continuous scalar order parameter field is discussed, which provides a convenient representation of the interface between locally crystal-like and locally liquid-like regions. A number of interfacial properties are straightforwardly evaluated using this procedure such as the average premelting thickness and surface tension. The temperature and system size dependence of the premelting layer thickness calculated in this way confirms the characteristic logarithmic growth expected for the scalar field theory that the system is mapped onto through coarse-graining, though remains finite due to long-ranged interactions. Finally, from explicit simulations the existence of a premelting layer is shown to be insensitive to bulk lattice geometry, exposed crystal face, and curvature

  20. Premelting, fluctuations, and coarse-graining of water-ice interfaces.

    Science.gov (United States)

    Limmer, David T; Chandler, David

    2014-11-14

    Using statistical field theory supplemented with molecular dynamics simulations, we consider premelting on the surface of ice as a generic consequence of broken hydrogen bonds at the boundary between the condensed and gaseous phases. A procedure for coarse-graining molecular configurations onto a continuous scalar order parameter field is discussed, which provides a convenient representation of the interface between locally crystal-like and locally liquid-like regions. A number of interfacial properties are straightforwardly evaluated using this procedure such as the average premelting thickness and surface tension. The temperature and system size dependence of the premelting layer thickness calculated in this way confirms the characteristic logarithmic growth expected for the scalar field theory that the system is mapped onto through coarse-graining, though remains finite due to long-ranged interactions. Finally, from explicit simulations the existence of a premelting layer is shown to be insensitive to bulk lattice geometry, exposed crystal face, and curvature.

  1. Reduced cerebral perfusion on sudden immersion in ice water: a possible cause of drowning

    DEFF Research Database (Denmark)

    Mantoni, Teit; Belhage, Bo; Pedersen, Lars M

    2007-01-01

    Near-drowning incidents and drowning deaths after accidental immersion in open waters have been linked to cold shock response. It consists of inspiratory gasps, hyperventilation, tachycardia, and hypertension in the first 2-3 min of cold-water immersion. This study explored the immediate changes...... in cerebral blood flow velocity (Vmean) during cold-water immersion since cold shock induced hyperventilation may diminish Vmean and lead to syncope and drowning....

  2. Neurobehavioral Grand Rounds introduction: Does near drowning in ice water prevent anoxic induced brain injury?

    Science.gov (United States)

    Hopkins, Ramona O

    2008-07-01

    Cold water near-drowning is often thought to be neuroprotective in individuals with anoxia of a longer duration than that usually required to produce irreversible neurologic damage. There is a paucity of data in adults with cold water near-drowning that assess neuropsychological outcomes. Information regarding long-term effects of near cold water near-drowning on neuropathology, neuropsychological and neurobehavioral outcomes are uncommon. This paper provides an introduction to two cases of cold water near-drowning reported in this issue of JINS by Sameulson and colleagues and provides background information for interpretation of the findings of these cases in the context of outcomes following anoxia.

  3. A rapid transition from ice covered CO2–rich waters to a biologically mediated CO2 sink in the eastern Weddell Gyre

    Directory of Open Access Journals (Sweden)

    W. Geibert

    2008-09-01

    Full Text Available Circumpolar Deep Water (CDW, locally called Warm Deep Water (WDW, enters the Weddell Gyre in the southeast, roughly at 25° E to 30° E. In December 2002 and January 2003 we studied the effect of entrainment of WDW on the fugacity of carbon dioxide (fCO2 and dissolved inorganic carbon (DIC in Weddell Sea surface waters. Ultimately the fCO2 difference across the sea surface drives air-sea fluxes of CO2. Deep CTD sections and surface transects of fCO2 were made along the Prime Meridian, a northwest-southeast section, and along 17° E to 23° E during cruise ANT XX/2 on FS Polarstern. Upward movement and entrainment of WDW into the winter mixed layer had significantly increased DIC and fCO2 below the sea ice along 0° W and 17° E to 23° E, notably in the southern Weddell Gyre. Nonetheless, the ice cover largely prevented outgassing of CO2 to the atmosphere. During and upon melting of the ice, biological activity rapidly reduced surface water fCO2 by up to 100 μatm, thus creating a sink for atmospheric CO2. Despite the tendency of the surfacing WDW to cause CO2 supersaturation, the Weddell Gyre may well be a CO2 sink on an annual basis due to this effective mechanism involving ice cover and ensuing biological fCO2 reduction. Dissolution of calcium carbonate (CaCO3 in melting sea ice may play a minor role in this rapid reduction of surface water fCO2.

  4. Supercooled Liquid Water Content Instrument Analysis and Winter 2014 Data with Comparisons to the NASA Icing Remote Sensing System and Pilot Reports

    Science.gov (United States)

    King, Michael C.

    2016-01-01

    The National Aeronautics and Space Administration (NASA) has developed a system for remotely detecting the hazardous conditions leading to aircraft icing in flight, the NASA Icing Remote Sensing System (NIRSS). Newly developed, weather balloon-borne instruments have been used to obtain in-situ measurements of supercooled liquid water during March 2014 to validate the algorithms used in the NIRSS. A mathematical model and a processing method were developed to analyze the data obtained from the weather balloon soundings. The data from soundings obtained in March 2014 were analyzed and compared to the output from the NIRSS and pilot reports.

  5. New evidence for surface water ice in small-scale cold traps and in three large craters at the north polar region of Mercury from the Mercury Laser Altimeter

    Science.gov (United States)

    Deutsch, Ariel N.; Neumann, Gregory A.; Head, James W.

    2017-09-01

    The Mercury Laser Altimeter (MLA) measured surface reflectance, rs, at 1064 nm. On Mercury, most water-ice deposits have anomalously low rs values indicative of an insulating layer beneath which ice is buried. Previous detections of surface water ice (without an insulating layer) were limited to seven possible craters. Here we map rs in three additional permanently shadowed craters that host radar-bright deposits. Each crater has a mean rs value >0.3, suggesting that water ice is exposed at the surface without an overlying insulating layer. We also identify small-scale cold traps (rs >0.3 and permanent shadows have biannual maximum surface temperatures <100 K. We suggest that a substantial amount of