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Sample records for hydrated electron-induced inactivation

  1. Electron-induced hydration of an alkene: alternative reaction pathways.

    Science.gov (United States)

    Warneke, Jonas; Wang, Ziyan; Swiderek, Petra; Bredehöft, Jan Hendrik

    2015-03-27

    Electron-induced reactions in condensed mixtures of ethylene and water lead to the synthesis of ethanol, as shown by post-irradiation thermal desorption spectrometry (TDS). Interestingly, this synthesis is not only induced by soft electron impact ionization similar to a previously observed electron-induced hydroamination but also, at low electron energy, by electron attachment to ethylene and a subsequent acid/base reaction with water.

  2. Gas hydrates

    Digital Repository Service at National Institute of Oceanography (India)

    Ramprasad, T.

    and the role it plays in the global climate and the future of fuels. Russia, Japan, Nigeria, Peru, Chile, Pakistan, Indonesia, Korea, etc are various countries who are perusing the gas hydrates studies as a future resource for fuel. Indian Initiative..., 1993, Free gas at the base of the gas hydrate zone in the vicinity of the Chile Triple junction: Geology, v. 21, pp. 905-908. Borowski, W.S., C.K. Paull, and U. William, III, 1999, Global and local variations of interstitial sulfate gradients...

  3. Clathrate hydrates in nature.

    Science.gov (United States)

    Hester, Keith C; Brewer, Peter G

    2009-01-01

    Scientific knowledge of natural clathrate hydrates has grown enormously over the past decade, with spectacular new findings of large exposures of complex hydrates on the sea floor, the development of new tools for examining the solid phase in situ, significant progress in modeling natural hydrate systems, and the discovery of exotic hydrates associated with sea floor venting of liquid CO2. Major unresolved questions remain about the role of hydrates in response to climate change today, and correlations between the hydrate reservoir of Earth and the stable isotopic evidence of massive hydrate dissociation in the geologic past. The examination of hydrates as a possible energy resource is proceeding apace for the subpermafrost accumulations in the Arctic, but serious questions remain about the viability of marine hydrates as an economic resource. New and energetic explorations by nations such as India and China are quickly uncovering large hydrate findings on their continental shelves.

  4. Kinetics and mechanism of electron-induced splitting of a cyclobutane pyrimidine dimer with or without an electron acceptor

    Institute of Scientific and Technical Information of China (English)

    YAN; Liqin(晏利琴); SONG; Qinhua(宋钦华); HEI; Xiaoming(黑晓明); WANG; Wenfeng(王文锋); GUO; Qingxiang(郭庆祥)

    2003-01-01

    Utilizing a pulse radiolysis equipment with time-resolved optical detector, kinetic processes of electron-induced splitting of cis-syn 1,3-dimethyluracil cyclobutane dimer (DMUD) in aqueous solution were investigated in the presence or absence of riboflavin (RF) or flavin adenine dinucleotide (FAD). It has been observed that the cyclobutane pyrimidine dimer reacting with hydrated electron splits spontaneously to give a monomer and a monomer radical anion, and the anion transfers one electron to RF or FAD. From the buildup kinetics of radical species, the rate constants of electron transfer from the monomer radical anion to RF and FAD have been determined. On the basis of comparison of the interactions between DMUD and hydrated electron in the presence and absence of RF or FAD, a chain reaction process in the absence of RF or FAD has been demonstrated.

  5. Hydrated Electron Transfer to Nucleobases in Aqueous Solutions Revealed by Ab Initio Molecular Dynamics Simulations.

    Science.gov (United States)

    Zhao, Jing; Wang, Mei; Fu, Aiyun; Yang, Hongfang; Bu, Yuxiang

    2015-08-03

    We present an ab initio molecular dynamics (AIMD) simulation study into the transfer dynamics of an excess electron from its cavity-shaped hydrated electron state to a hydrated nucleobase (NB)-bound state. In contrast to the traditional view that electron localization at NBs (G/A/C/T), which is the first step for electron-induced DNA damage, is related only to dry or prehydrated electrons, and a fully hydrated electron no longer transfers to NBs, our AIMD simulations indicate that a fully hydrated electron can still transfer to NBs. We monitored the transfer dynamics of fully hydrated electrons towards hydrated NBs in aqueous solutions by using AIMD simulations and found that due to solution-structure fluctuation and attraction of NBs, a fully hydrated electron can transfer to a NB gradually over time. Concurrently, the hydrated electron cavity gradually reorganizes, distorts, and even breaks. The transfer could be completed in about 120-200 fs in four aqueous NB solutions, depending on the electron-binding ability of hydrated NBs and the structural fluctuation of the solution. The transferring electron resides in the π*-type lowest unoccupied molecular orbital of the NB, which leads to a hydrated NB anion. Clearly, the observed transfer of hydrated electrons can be attributed to the strong electron-binding ability of hydrated NBs over the hydrated electron cavity, which is the driving force, and the transfer dynamics is structure-fluctuation controlled. This work provides new insights into the evolution dynamics of hydrated electrons and provides some helpful information for understanding the DNA-damage mechanism in solution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Origins of hydration lubrication.

    Science.gov (United States)

    Ma, Liran; Gaisinskaya-Kipnis, Anastasia; Kampf, Nir; Klein, Jacob

    2015-01-14

    Why is friction in healthy hips and knees so low? Hydration lubrication, according to which hydration shells surrounding charges act as lubricating elements in boundary layers (including those coating cartilage in joints), has been invoked to account for the extremely low sliding friction between surfaces in aqueous media, but not well understood. Here we report the direct determination of energy dissipation within such sheared hydration shells. By trapping hydrated ions in a 0.4-1 nm gap between atomically smooth charged surfaces as they slide past each other, we are able to separate the dissipation modes of the friction and, in particular, identify the viscous losses in the subnanometre hydration shells. Our results shed light on the origins of hydration lubrication, with potential implications both for aqueous boundary lubricants and for biolubrication.

  7. Inactivation Data.xlsx

    Data.gov (United States)

    U.S. Environmental Protection Agency — The data set is a spreadsheet that contains results of inactivation experiments that were conducted to to determine the effectiveness of chlorine in inactivating B....

  8. Hydration Assessment of Athletes

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ KEY POINTS · Although there is no scientific consensus for 1 ) howbest to assess the hydration status of athletes, 2)what criteria to use as acceptable outcome measurements, or 3) the best time to apply practical assessment methods, there are methods that can be used toprovide athletes with useful feedback about their hydration status

  9. Inactivation of Caliciviruses

    Science.gov (United States)

    Nims, Raymond; Plavsic, Mark

    2013-01-01

    The Caliciviridae family of viruses contains clinically important human and animal pathogens, as well as vesivirus 2117, a known contaminant of biopharmaceutical manufacturing processes employing Chinese hamster cells. An extensive literature exists for inactivation of various animal caliciviruses, especially feline calicivirus and murine norovirus. The caliciviruses are susceptible to wet heat inactivation at temperatures in excess of 60 °C with contact times of 30 min or greater, to UV-C inactivation at fluence ≥30 mJ/cm2, to high pressure processing >200 MPa for >5 min at 4 °C, and to certain photodynamic inactivation approaches. The enteric caliciviruses (e.g.; noroviruses) display resistance to inactivation by low pH, while the non-enteric species (e.g.; feline calicivirus) are much more susceptible. The caliciviruses are inactivated by a variety of chemicals, including alcohols, oxidizing agents, aldehydes, and β-propiolactone. As with inactivation of viruses in general, inactivation of caliciviruses by the various approaches may be matrix-, temperature-, and/or contact time-dependent. The susceptibilities of the caliciviruses to the various physical and chemical inactivation approaches are generally similar to those displayed by other small, non-enveloped viruses, with the exception that the parvoviruses and circoviruses may require higher temperatures for inactivation, while these families appear to be more susceptible to UV-C inactivation than are the caliciviruses. PMID:24276023

  10. Inactivation of Caliciviruses

    Directory of Open Access Journals (Sweden)

    Raymond Nims

    2013-03-01

    Full Text Available The Caliciviridae family of viruses contains clinically important human and animal pathogens, as well as vesivirus 2117, a known contaminant of biopharmaceutical manufacturing processes employing Chinese hamster cells. An extensive literature exists for inactivation of various animal caliciviruses, especially feline calicivirus and murine norovirus. The caliciviruses are susceptible to wet heat inactivation at temperatures in excess of 60 °C with contact times of 30 min or greater, to UV-C inactivation at fluence ≥30 mJ/cm2, to high pressure processing >200 MPa for >5 min at 4 °C, and to certain photodynamic inactivation approaches. The enteric caliciviruses (e.g.; noroviruses display resistance to inactivation by low pH, while the non-enteric species (e.g.; feline calicivirus are much more susceptible. The caliciviruses are inactivated by a variety of chemicals, including alcohols, oxidizing agents, aldehydes, and β-propiolactone. As with inactivation of viruses in general, inactivation of caliciviruses by the various approaches may be matrix-, temperature-, and/or contact time-dependent. The susceptibilities of the caliciviruses to the various physical and chemical inactivation approaches are generally similar to those displayed by other small, non-enveloped viruses, with the exception that the parvoviruses and circoviruses may require higher temperatures for inactivation, while these families appear to be more susceptible to UV-C inactivation than are the caliciviruses.

  11. Hydration rate of obsidian.

    Science.gov (United States)

    Friedman, I; Long, W

    1976-01-30

    The hydration rates of 12 obsidian samples of different chemical compositions were measured at temperatures from 95 degrees to 245 degrees C. An expression relating hydration rate to temperature was derived for each sample. The SiO(2) content and refractive index are related to the hydration rate, as are the CaO, MgO, and original water contents. With this information it is possible to calculate the hydration rate of a sample from its silica content, refractive index, or chemical index and a knowledge of the effective temperature at which the hydration occurred. The effective hydration temperature can be either measured or approximated from weather records. Rates have been calculated by both methods, and the results show that weather records can give a good approximation to the true EHT, particularly in tropical and subtropical climates. If one determines the EHT by any of the methods suggested, and also measures or knows the rate of hydration of the particular obsidian used, it should be possible to carry out absolute dating to +/- 10 percent of the true age over periods as short as several years and as long as millions of years.

  12. Hydrate morphology: Physical properties of sands with patchy hydrate saturation

    Science.gov (United States)

    Dai, S.; Santamarina, J.C.; Waite, William F.; Kneafsey, T.J.

    2012-01-01

    The physical properties of gas hydrate-bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate morphology in sediments; this information can be used to significantly constrain estimates of the physical properties of hydrate-bearing sediments, including the coarse-grained sands subjected to high effective stress that are of interest as potential energy resources. Reported data and physical analyses suggest hydrate-bearing sands contain a heterogeneous, patchy hydrate distribution, whereby zones with 100% pore-space hydrate saturation are embedded in hydrate-free sand. Accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate-bearing sands and captures observed physical-property dependencies on hydrate saturation. For example, numerical modeling results of sands with patchy saturation agree with experimental observation, showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations. The hydrate-patch size itself impacts the physical properties of hydrate-bearing sediments; for example, at constant hydrate saturation, we find that conductivity (electrical, hydraulic and thermal) increases as the number of hydrate-saturated patches increases. This increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate-saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross-section of the specimen.

  13. Wet hydrate dissolution plant

    OpenAIRE

    Stanković Mirjana S.; Kovačević Branimir T.; Pezo Lato L.

    2003-01-01

    The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with capacity of 50,000 t/y was manufactured, at "Zeolite Mira", Mira (VE), Italy, in 1997, for increasing detergent zeolite production from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate ...

  14. Hot electron induced NIR detection in CdS films.

    Science.gov (United States)

    Sharma, Alka; Kumar, Rahul; Bhattacharyya, Biplab; Husale, Sudhir

    2016-03-11

    We report the use of random Au nanoislands to enhance the absorption of CdS photodetectors at wavelengths beyond its intrinsic absorption properties from visible to NIR spectrum enabling a high performance visible-NIR photodetector. The temperature dependent annealing method was employed to form random sized Au nanoparticles on CdS films. The hot electron induced NIR photo-detection shows high responsivity of ~780 mA/W for an area of ~57 μm(2). The simulated optical response (absorption and responsivity) of Au nanoislands integrated in CdS films confirms the strong dependence of NIR sensitivity on the size and shape of Au nanoislands. The demonstration of plasmon enhanced IR sensitivity along with the cost-effective device fabrication method using CdS film enables the possibility of economical light harvesting applications which can be implemented in future technological applications.

  15. PART II. HYDRATED CEMENTS

    Directory of Open Access Journals (Sweden)

    Milan Drabik

    2014-09-01

    Full Text Available Essential focus of the study has been to acquire thermoanalytical events, incl. enthalpies of decompositions - ΔH, of technological materials based on two types of Portland cements. The values of thermoanalytical events and also ΔH of probes of technological compositions, if related with the data of a choice of minerals of calcium-silicate-sulfate-aluminate hydrates, served as a valued input for the assessment of phases present and phase changes due to the topical hydraulic processes. The results indicate mainly the effects of "standard humidity" or "wet storage" of the entire hydration/hydraulic treatment, but also the presence of cement residues alongside calcium-silicate-sulfate-aluminate hydrates (during the tested period of treatment. "A diluting" effect of unhydrated cement residues upon the values of decomposition enthalpies in the studied multiphase system is postulated and discussed

  16. Formation of porous gas hydrates

    CERN Document Server

    Salamatin, Andrey N

    2015-01-01

    Gas hydrates grown at gas-ice interfaces are examined by electron microscopy and found to have a submicron porous texture. Permeability of the intervening hydrate layers provides the connection between the two counterparts (gas and water molecules) of the clathration reaction and makes further hydrate formation possible. The study is focused on phenomenological description of principal stages and rate-limiting processes that control the kinetics of the porous gas hydrate crystal growth from ice powders. Although the detailed physical mechanisms involved in the porous hydrate formation still are not fully understood, the initial stage of hydrate film spreading over the ice surface should be distinguished from the subsequent stage which is presumably limited by the clathration reaction at the ice-hydrate interface and develops after the ice grain coating is finished. The model reveals a time dependence of the reaction degree essentially different from that when the rate-limiting step of the hydrate formation at...

  17. Tunneling electron induced luminescence from porphyrin molecules on monolayer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Feng; Kuang, Yanmin; Yu, Yunjie; Liao, Yuan; Zhang, Yao; Zhang, Yang; Dong, Zhenchao, E-mail: zcdong@ustc.edu.cn

    2015-01-15

    Using epitaxially grown graphene on Ru(0001) as a decoupling layer, we investigate the evolution of tunneling electron induced luminescence from different number of layers of porphyrin molecules. Light emission spectra and photon maps, acquired via a combined optical setup with scanning tunneling microscopy (STM), indicate that the electronic decoupling effect of a monolayer (ML) graphene alone is still insufficient for generating molecule-specific emission from both the 1st- and 2nd-layer porphyrin molecules. Nevertheless, interestingly, the plasmonic emission is enhanced for the 1st-layer but suppressed for the 2nd-layer in comparison with the plasmonic emission on the monolayer graphene. Intrinsic intramolecular molecular fluorescence occurs at the 3rd-layer porphyrin. Such molecular thickness is about two MLs thinner than previous reports where molecules were adsorbed directly on metals. These observations suggest that the monolayer graphene does weaken the interaction between molecule and metal substrate and contribute to the reduction of nonradiative decay rates. - Highlights: • Showing molecularly resolved photon maps of graphene and porphyrins on it. • Revealing the influence of spacer thickness on molecular electroluminescence. • Graphene does weaken the interaction between molecules and metal substrate.

  18. [Hydration in clinical practice].

    Science.gov (United States)

    Maristany, Cleofé Pérez-Portabella; Segurola Gurruchaga, Hegoi

    2011-01-01

    Water is an essential foundation for life, having both a regulatory and structural function. The former results from active and passive participation in all metabolic reactions, and its role in conserving and maintaining body temperature. Structurally speaking it is the major contributer to tissue mass, accounting for 60% of the basis of blood plasma, intracellular and intersticial fluid. Water is also part of the primary structures of life such as genetic material or proteins. Therefore, it is necessary that the nurse makes an early assessment of patients water needs to detect if there are signs of electrolyte imbalance. Dehydration can be a very serious problem, especially in children and the elderly. Dehydrations treatment with oral rehydration solution decreases the risk of developing hydration disorders, but even so, it is recommended to follow preventive measures to reduce the incidence and severity of dehydration. The key to having a proper hydration is prevention. Artificial nutrition encompasses the need for precise calculation of water needs in enteral nutrition as parenteral, so the nurse should be part of this process and use the tools for calculating the patient's requirements. All this helps to ensure an optimal nutritional status in patients at risk. Ethical dilemmas are becoming increasingly common in clinical practice. On the subject of artificial nutrition and hydration, there isn't yet any unanimous agreement regarding hydration as a basic care. It is necessary to take decisions in consensus with the health team, always thinking of the best interests of the patient.

  19. Modeling Hydrates and the Gas Hydrate Markup Language

    Directory of Open Access Journals (Sweden)

    Weihua Wang

    2007-06-01

    Full Text Available Natural gas hydrates, as an important potential fuels, flow assurance hazards, and possible factors initiating the submarine geo-hazard and global climate change, have attracted the interest of scientists all over the world. After two centuries of hydrate research, a great amount of scientific data on gas hydrates has been accumulated. Therefore the means to manage, share, and exchange these data have become an urgent task. At present, metadata (Markup Language is recognized as one of the most efficient ways to facilitate data management, storage, integration, exchange, discovery and retrieval. Therefore the CODATA Gas Hydrate Data Task Group proposed and specified Gas Hydrate Markup Language (GHML as an extensible conceptual metadata model to characterize the features of data on gas hydrate. This article introduces the details of modeling portion of GHML.

  20. Overview: Nucleation of clathrate hydrates

    Science.gov (United States)

    Warrier, Pramod; Khan, M. Naveed; Srivastava, Vishal; Maupin, C. Mark; Koh, Carolyn A.

    2016-12-01

    Molecular level knowledge of nucleation and growth of clathrate hydrates is of importance for advancing fundamental understanding on the nature of water and hydrophobic hydrate formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when hydrate structures nucleate will be tremendously beneficial for the development of sustainable hydrate management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of hydrate nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to hydrates. Hydrate nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various hydrate nucleation hypotheses and hydrate nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on hydrate nucleation are discussed in detail followed by potential future research directions.

  1. A study on gas hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Byoung Jae; Jung, Tae Jin; Sunwoo, Don [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1996-12-01

    Sufficient documents were reviewed to understand solid components of water and gaseous hydrocarbon known as gas hydrates, which represent an important potential energy resource of the future. The review provides us with valuable information on crystal structures, kinetics, origin and distribution of gas hydrates. In addition, the review increased our knowledge of exploration and development methods of gas hydrates. Large amounts of methane, the principal component of natural gas, in the form of solid gas hydrate are found mainly offshore in outer continental margin sediment and, to a lesser extent, in polar regions commonly associated with permafrost. Natural gas hydrates are stable in some environments where the hydrostatic pressure exerted by overlying water column is sufficient for hydrate formation and stability. The required high pressures generally restrict gas hydrate to sediments beneath water of approximately 400 m. Higher sediment temperatures at greater subbottom depths destabilize gas hydrates. Based on the pressure- temperature condition, the outer continental margin of East Sea where water depth is deep enough to form gas hydrate is considered to have high potential of gas hydrate accumulations. (author). 56 refs., tabs., figs.

  2. Drilling Gas Hydrates on hydrate Ridge, Oregon continental margin

    Science.gov (United States)

    Trehu, A. M.; Bohrmann, G.; Leg 204 Science Party

    2002-12-01

    During Leg 204, we cored and logged 9 sites on the Oregon continental margin to determine the distribution and concentration of gas hydrates in an accretionary ridge and adjacent slope basin, investigate the mechanisms that transport methane and other gases into the gas hydrate stability zone (GHSZ), and obtain constraints on physical properties of hydrates in situ. A 3D seismic survey conducted in 2000 provided images of potential subsurface fluid conduits and indicated the position of the GHSZ throughout the survey region. After coring the first site, we acquired Logging-While-Drilling (LWD) data at all but one site to provide an overview of downhole physical properties. The LWD data confirmed the general position of key seismic stratigraphic horizons and yielded an initial estimate of hydrate concentration through the proxy of in situ electrical resistivity. These records proved to be of great value in planning subsequent coring. The second new hydrate proxy to be tested was infrared thermal imaging of cores on the catwalk as rapidly as possible after retrieval. The thermal images were used to identify hydrate samples and to estimate the distribution and texture of hydrate within the cores. Geochemical analyses of interstitial waters and of headspace and void gases provide additional information on the distribution and concentration of hydrate within the stability zone, the origin and pathway of fluids into and through the GHSZ, and the rates at which gas hydrate is forming. Bio- and lithostratigraphic description of cores, measurement of physical properties, and in situ pressure core sampling and thermal measurements complement the data set, providing ground-truth tests of inferred physical and sedimentological properties. Among the most interesting preliminary results are: 1) that gas hydrates are distributed through a broad depth range within the GHSZ and that different physical and chemical proxies for hydrate distribution and concentration give generally

  3. Rapid gas hydrate formation process

    Science.gov (United States)

    Brown, Thomas D.; Taylor, Charles E.; Unione, Alfred J.

    2013-01-15

    The disclosure provides a method and apparatus for forming gas hydrates from a two-phase mixture of water and a hydrate forming gas. The two-phase mixture is created in a mixing zone which may be wholly included within the body of a spray nozzle. The two-phase mixture is subsequently sprayed into a reaction zone, where the reaction zone is under pressure and temperature conditions suitable for formation of the gas hydrate. The reaction zone pressure is less than the mixing zone pressure so that expansion of the hydrate-forming gas in the mixture provides a degree of cooling by the Joule-Thompson effect and provides more intimate mixing between the water and the hydrate-forming gas. The result of the process is the formation of gas hydrates continuously and with a greatly reduced induction time. An apparatus for conduct of the method is further provided.

  4. Hydration and physical performance.

    Science.gov (United States)

    Murray, Bob

    2007-10-01

    There is a rich scientific literature regarding hydration status and physical function that began in the late 1800s, although the relationship was likely apparent centuries before that. A decrease in body water from normal levels (often referred to as dehydration or hypohydration) provokes changes in cardiovascular, thermoregulatory, metabolic, and central nervous function that become increasingly greater as dehydration worsens. Similarly, performance impairment often reported with modest dehydration (e.g., -2% body mass) is also exacerbated by greater fluid loss. Dehydration during physical activity in the heat provokes greater performance decrements than similar activity in cooler conditions, a difference thought to be due, at least in part, to greater cardiovascular and thermoregulatory strain associated with heat exposure. There is little doubt that performance during prolonged, continuous exercise in the heat is impaired by levels of dehydration >or= -2% body mass, and there is some evidence that lower levels of dehydration can also impair performance even during relatively short-duration, intermittent exercise. Although additional research is needed to more fully understand low-level dehydration's effects on physical performance, one can generalize that when performance is at stake, it is better to be well-hydrated than dehydrated. This generalization holds true in the occupational, military, and sports settings.

  5. Ductile flow of methane hydrate

    Science.gov (United States)

    Durham, W.B.; Stern, L.A.; Kirby, S.H.

    2003-01-01

    Compressional creep tests (i.e., constant applied stress) conducted on pure, polycrystalline methane hydrate over the temperature range 260-287 K and confining pressures of 50-100 MPa show this material to be extraordinarily strong compared to other icy compounds. The contrast with hexagonal water ice, sometimes used as a proxy for gas hydrate properties, is impressive: over the thermal range where both are solid, methane hydrate is as much as 40 times stronger than ice at a given strain rate. The specific mechanical response of naturally occurring methane hydrate in sediments to environmental changes is expected to be dependent on the distribution of the hydrate phase within the formation - whether arranged structurally between and (or) cementing sediments grains versus passively in pore space within a sediment framework. If hydrate is in the former mode, the very high strength of methane hydrate implies a significantly greater strain-energy release upon decomposition and subsequent failure of hydrate-cemented formations than previously expected.

  6. Some thermodynamical aspects of protein hydration water

    Energy Technology Data Exchange (ETDEWEB)

    Mallamace, Francesco, E-mail: francesco.mallamace@unime.it [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Corsaro, Carmelo [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); CNR-IPCF, Viale F. Stagno D’Alcontres 37, I-98158 Messina (Italy); Mallamace, Domenico [Dipartimento SASTAS, Università di Messina, I-98166 Messina (Italy); Vasi, Sebastiano [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); Vasi, Cirino [CNR-IPCF, Viale F. Stagno D’Alcontres 37, I-98158 Messina (Italy); Stanley, H. Eugene [Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Chen, Sow-Hsin [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-06-07

    We study by means of nuclear magnetic resonance the self-diffusion of protein hydration water at different hydration levels across a large temperature range that includes the deeply supercooled regime. Starting with a single hydration shell (h = 0.3), we consider different hydrations up to h = 0.65. Our experimental evidence indicates that two phenomena play a significant role in the dynamics of protein hydration water: (i) the measured fragile-to-strong dynamic crossover temperature is unaffected by the hydration level and (ii) the first hydration shell remains liquid at all hydrations, even at the lowest temperature.

  7. Hydrazine inactivates bacillus spores

    Science.gov (United States)

    Schubert, Wayne; Plett, G. A.; Yavrouian, A. H.; Barengoltz, J.

    2005-01-01

    Planetary Protection places requirements on the maximum number of viable bacterial spores that may be delivered by a spacecraft to another solar system body. Therefore, for such space missions, the spores that may be found in hydrazine are of concern. A proposed change in processing procedures that eliminated a 0.2 um filtration step propmpted this study to ensure microbial contamination issue existed, especially since no information was found in the literature to substantiate bacterial spore inactivation by hydrazine.

  8. Flow assurance intervention, hydrates remediation

    Energy Technology Data Exchange (ETDEWEB)

    Mancini, Christopher S. [Oceaneering International Inc., Houston, TX (United States)

    2012-07-01

    This paper addresses the issues of removing hydrates in sub sea flow lines and associated equipment with an Remotely Operated Vehicle (ROV) of opportunity and a multi-service-vessel (MSV). The paper is split into three topics: the equipment used with the ROV, assessing the interface points and handling fluids produced from drawing down the pressure. Each section is explained thoroughly and backed up with real world experience. The equipment section details information from actual jobs performed and why the particular components were utilized. The system is generally contained in an ROV mounted skid. Pumps are utilized to draw down the pressure inside the hydrated section of equipment, removing one of the three necessary components for hydrates formation. Once the section is pumped down, several options exist for handling the fluids pumped out of the system: pumping to surface, re-injection into the well, or injection into an operating flow line. This method of hydrates remediation is both economical and timely. Hydrate blockages form in low temperatures and high pressures. Reducing the pressure or increasing the temperature so the conditions lie to the right of the hydrate dissociation curve will slowly decompose the blockage. Depressurization and the use of MEG or methanol will give favorable conditions to remove the hydrate plug. Oceaneering has the capabilities to remove hydrates using the FRS in conjunction with an installation vessel to dispose of the gas and fluid removed from the flow line. Hydrate remediation techniques should be implemented into the initial design to reduce costs later. The cost of stopped production combined with the day rate for equipment needed for hydrate removal outweighs the costs if no technique is utilized. (author)

  9. Investigation on Gas Storage in Methane Hydrate

    Institute of Scientific and Technical Information of China (English)

    Zhigao Sun; Rongsheng Ma; Shuanshi Fan; Kaihua Guo; Ruzhu Wang

    2004-01-01

    The effect of additives (anionic surfactant sodium dodecyl sulfate (SDS), nonionic surfactant alkyl polysaccharide glycoside (APG), and liquid hydrocarbon cyclopentane (CP)) on hydrate induction time and formation rate, and storage capacity was studied in this work. Micelle surfactant solutions were found to reduce hydrate induction time, increase methane hydrate formation rate and improve methane storage capacity in hydrates. In the presence of surfactant, hydrate could form quickly in a quiescent system and the energy costs of hydrate formation were reduced. The critical micelle concentrations of SDS and APG water solutions were found to be 300× 10-6 and 500× 10-6 for methane hydrate formation system respectively. The effect of anionic surfactant (SDS) on methane storage in hydrates is more pronounced compared to a nonionic surfactant (APG). CP also reduced hydrate induction time and improved hydrate formation rate, but could not improve methane storage in hydrates.

  10. Hydrates fighting tools; Des outils de lutte contre les hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2003-04-01

    Shell Exploration and Production company (SEPCo) is the operator of the 'Popeye' deep offshore field in the Gulf of Mexico. Thanks to the introduction of a low dosing hydrates inhibitor (LDHI) elaborated by Shell Global Solutions, the company has added a 7.5 Gpc extra volume of gas to its recoverable reserves. This new technology avoids the plugging of pipes by hydrates formation. (J.S.)

  11. Obsidian Hydration: A New Paleothermometer

    Energy Technology Data Exchange (ETDEWEB)

    Anovitz, Lawrence {Larry} M [ORNL; Riciputi, Lee R [ORNL; Cole, David R [ORNL; Fayek, Mostafa [ORNL; Elam, J. Michael [University of Tennessee, Knoxville (UTK)

    2006-01-01

    The natural hydration of obsidian was first proposed as a dating technique for young geological and archaeological specimens by Friedman and Smith (1960), who noted that the thickness of the hydrated layer on obsidian artifacts increases with time. This approach is, however, sensitive to temperature and humidity under earth-surface conditions. This has made obsidian hydration dating more difficult, but potentially provides a unique tool for paleoclimatic reconstructions. In this paper we present the first successful application of this approach, based on combining laboratory-based experimental calibrations with archaeological samples from the Chalco site in the Basin of Mexico, dated using stratigraphically correlated 14C results and measuring hydration depths by secondary ion mass spectrometry. The resultant data suggest, first, that this approach is viable, even given the existing uncertainties, and that a cooling trend occurred in the Basin of Mexico over the past 1450 yr, a result corroborated by other paleoclimatic data.

  12. Obsidian hydration: A new paleothermometer

    Science.gov (United States)

    Anovitz, Lawrence M.; Riciputi, Lee R.; Cole, David R.; Fayek, Mostafa; Elam, J. Michael

    2006-07-01

    The natural hydration of obsidian was first proposed as a dating technique for young geological and archaeological specimens by Friedman and Smith (1960), who noted that the thickness of the hydrated layer on obsidian artifacts increases with time. This approach is, however, sensitive to temperature and humidity under earth-surface conditions. This has made obsidian hydration dating more difficult, but potentially provides a unique tool for paleoclimatic reconstructions. In this paper we present the first successful application of this approach, based on combining laboratory-based experimental calibrations with archaeological samples from the Chalco site in the Basin of Mexico, dated using stratigraphically correlated 14C results and measuring hydration depths by secondary ion mass spectrometry. The resultant data suggest, first, that this approach is viable, even given the existing uncertainties, and that a cooling trend occurred in the Basin of Mexico over the past 1450 yr, a result corroborated by other paleoclimatic data.

  13. Obsidian hydration dates glacial loading?

    Science.gov (United States)

    Friedman, I; Pierce, K L; Obradovich, J D; Long, W D

    1973-05-18

    Three different groups of hydration rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of hydration rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average hydration rind thicknesses of 14.5 and 7.9 micrometers. These later two hydration rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.

  14. Storing natural gas as frozen hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Gudmundsson, J.S.; Khokhar, A.A. (Univ. of Trondheim (Norway)); Parlaktuna, M. (Middle East Technical Univ., Ankara (Turkey))

    1994-02-01

    The formation of natural gas hydrates is a well-known problem in the petroleum and natural gas industries. Hydrates are solid materials that form when liquid water and natural gas are brought in contact under pressure. Hydrate formation need not be a problem. On the contrary, it can be an advantage. The volume of hydrates is much less than that of natural gas. At standard conditions, hydrates occupy 150 to 170 times less volume than the corresponding gas. Typically, natural gas hydrates contain 15% gas and 85% water by mass. It follows that hydrates can be used for large-scale storage of natural gas. Benesh proposed using hydrates to improve the load factor of natural gas supply systems. The author suggested that hydrates could be produced by bringing liquid water into contact with natural gas at the appropriate temperature and high pressure. The hydrate then would be stored at a temperature and pressure where it was stable. When gas was needed for the supply system, the hydrate would be melted at low pressure. The stability of a natural gas hydrate during storage at atmospheric pressure and below-freezing temperatures was studied in the laboratory. The gas hydrate was produced in a stirred vessel at 2- to 6-MPa pressure and temperatures from 0 to 20 C. The hydrate was refrigerated and stored in deep freezers at [minus]5, [minus]10, and [minus]18 C for up to 10 days. The natural gas hydrate remained stable when kept frozen at atmospheric pressure.

  15. Airway Hydration and COPD

    Science.gov (United States)

    Ghosh, Arunava; Boucher, R.C.; Tarran, Robert

    2015-01-01

    Chronic obstructive pulmonary disease (COPD) is one of the prevalent causes of worldwide mortality and encompasses two major clinical phenotypes, i.e., chronic bronchitis (CB) and emphysema. The most common cause of COPD is chronic tobacco inhalation. Research focused on the chronic bronchitic phenotype of COPD has identified several pathological processes that drive disease initiation and progression. For example, the lung’s mucociliary clearance (MCC) system performs the critical task of clearing inhaled pathogens and toxic materials from the lung. MCC efficiency is dependent on: (i) the ability of apical plasma membrane ion channels such as the cystic fibrosis transmembrane conductance regulator (CFTR) and the epithelial Na+ channel (ENaC) to maintain airway hydration; (ii) ciliary beating; and, (iii) appropriate rates of mucin secretion. Each of these components is impaired in CB and likely contributes to the mucus stasis/accumulation seen in CB patients. This review highlights the cellular components responsible for maintaining MCC and how this process is disrupted following tobacco exposure and with CB. We shall also discuss existing therapeutic strategies for the treatment of chronic bronchitis and how components of the MCC can be used as biomarkers for the evaluation of tobacco or tobacco-like-product exposure. PMID:26068443

  16. Mechanism of gypsum hydration

    Directory of Open Access Journals (Sweden)

    Pacheco, G.

    1991-06-01

    Full Text Available There is an hypothesis that the mechanism o f gypsum hydration and dehydration is performed through two simultaneous phenomena. In this study we try to clear up this phenomenon using chlorides as accelerators or a mixture of ethanol-methanol as retarders to carry out the gypsum setting. Natural Mexican gypsum samples and a hemihydrate prepared in the laboratory are used. The following analytical techniques are used: MO, DRX, DTA, TG and DTG. In agreement with the obtained results, it can be concluded: that colloid formation depends on the action of accelerators or retarders and the crystals are a consequence of the quantity of hemihydrate formed.

    En el mecanismo de hidratación y deshidratación del yeso existe la hipótesis de que éste se efectúa por dos fenómenos simultáneos. Este estudio intenta esclarecer estos fenómenos, empleando: cloruros como aceleradores o mezcla etanol-metanol como retardadores para efectuar el fraguado del yeso. Se emplean muestras de yeso de origen natural mexicano y hemihydrate preparado en laboratorio; se utilizan técnicas analíticas: MO, DRX, DTA, TG y DTG. De acuerdo a los resultados obtenidos se puede deducir: que la formación del coloide depende de la acción de los agentes aceleradores o retardadores y que los cristales son consecuencia de la cantidad de hemihidrato formado.

  17. Dynamics of X Chromosome Inactivation

    NARCIS (Netherlands)

    F. Loos (Friedemann)

    2015-01-01

    markdownabstract__Abstract__ Dosage compensation evolved to account for the difference in expression of sex chromosome-linked genes. In mammals dosage compensation is achieved by inactivation of one X chromosome during early female embryogenesis in a process called X chromosome inactivation (XCI).

  18. Inactivation of Microorganisms

    Science.gov (United States)

    Alzamora, Stella Maris; Guerrero, Sandra N.; Schenk, Marcela; Raffellini, Silvia; López-Malo, Aurelio

    Minimal processing techniques for food preservation allow better retention of product flavor, texture, color, and nutrient content than comparable conventional treatments. A wide range of novel alternative physical factors have been intensely investigated in the last two decades. These physical factors can cause inactivation of microorganisms at ambient or sublethal temperatures (e.g., high hydrostatic pressure, pulsed electric fields, ultrasound, pulsed light, and ultraviolet light). These technologies have been reported to reduce microorganism population in foods while avoiding the deleterious effects of severe heating on quality. Among technologies, high-energy ultrasound (i.e., intensities higher than 1 W/cm2, frequencies between 18 and 100 kHz) has attracted considerable interest for food preservation applications (Mason et al., 1996; Povey and Mason, 1998).

  19. Diverse Electron-Induced Optical Emissions from Space Observatory Materials at Low Temperatures

    Science.gov (United States)

    Dennison, J.R.; Jensen, Amberly Evans; Wilson, Gregory; Dekany, Justin; Bowers, Charles W.; Meloy, Robert

    2013-01-01

    Electron irradiation experiments have investigated the diverse electron-induced optical and electrical signatures observed in ground-based tests of various space observatory materials at low temperature. Three types of light emission were observed: (i); long-duration cathodoluminescence which persisted as long as the electron beam was on (ii) short-duration (affect the performance of space-based observatories.

  20. Sequence dependence of electron-induced DNA strand breakage revealed by DNA nanoarrays

    DEFF Research Database (Denmark)

    Keller, Adrian; Rackwitz, Jenny; Cauët, Emilie;

    2014-01-01

    sections for electron induced single strand breaks in specific 13 mer oligonucleotides we used atomic force microscopy analysis of DNA origami based DNA nanoarrays. We investigated the DNA sequences 5'-TT(XYX)3TT with X = A, G, C and Y = T, BrU 5-bromouracil and found absolute strand break cross sections...

  1. Role of NH3 in the Electron-Induced Reactions of Adsorbed and Solid Cisplatin

    NARCIS (Netherlands)

    Warneke, Jonas; Rohdenburg, Markus; Zhang, Yucheng; Orzagh, Juraj; Vaz, Alfredo; Utke, Ivo; De Hosson, Jeff Th M.; van Dorp, Willem F.; Swiderek, Petra

    2016-01-01

    The electron-induced decomposition of cisplatin (cis-Pt(NH3)(2)Cl-2) was investigated to reveal if ammine (NH3) ligands have a favorable effect on the purity of deposits produced from metal-containing precursor molecules by focused electron beam induced deposition (FEBID). Scanning electron microsco

  2. Tetrahydrofuran hydrate decomposition characteristics in porous media

    Science.gov (United States)

    Song, Yongchen; Wang, Pengfei; Wang, Shenglong; Zhao, Jiafei; Yang, Mingjun

    2016-12-01

    Many tetrahydrofuran (THF) hydrate properties are similar to those of gas hydrates. In the present work THF hydrate dissociation in four types of porous media is studied. THF solution was cooled to 275.15 K with formation of the hydrate under ambient pressure, and then it dissociated under ambient conditions. THF hydrate dissociation experiments in each porous medium were conducted three times. Magnetic resonance imaging (MRI) was used to obtain images. Decomposition time, THF hydrate saturation and MRI mean intensity (MI) were measured and analyzed. The experimental results showed that the hydrate decomposition time in BZ-4 and BZ-3 was similar and longer than that in BZ-02. In each dissociation process, the hydrate decomposition time of the second and third cycles was shorter than that of the first cycle in BZ-4, BZ-3, and BZ-02. The relationship between THF hydrate saturation and time is almost linear.

  3. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben; Lachowski, Eric E.;

    1999-01-01

    Vapour phase hydration of purl cement clinker minerals at reduced relative humidities is described. This is relevant to modern high performance concrete that may self-desiccate during hydration and is also relevant to the quality of the cement during storage. Both the oretical considerations...... and experimental data are presented showing that C(3)A can hydrate at lower humidities than either C3S or C2S. It is suggested that the initiation of hydration during exposure to water vapour is nucleation controlled. When C(3)A hydrates at low humidity, the characteristic hydration product is C(3)AH(6...

  4. Progress of Gas Hydrate Studies in China

    Institute of Scientific and Technical Information of China (English)

    樊栓狮; 汪集旸

    2006-01-01

    A brief overview is given on the gas hydrate-related research activities carried out by Chinese researchers in the past 15 years. The content involves: (1) Historical review. Introducing the gas hydrate research history in China; (2) Gas hydrate research groups in China. There are nearly 20 groups engaged in gas hydrate research now; (3) Present studies.Including fundamental studies, status of the exploration of natural gas hydrate resources in the South China Sea region, and development of hydrate-based new techniques; (4) Future development.

  5. Hydration of fly ash cement

    Energy Technology Data Exchange (ETDEWEB)

    Etsuo Sakai; Shigeyoshi Miyahara; Shigenari Ohsawa; Seung-Heun Lee; Masaki Daimon [Tokyo Institute of Technology, Tokyo (Japan). Department of Metallurgy and Ceramics Science, Graduate School of Science and Engineering

    2005-06-01

    It is necessary to establish the material design system for the utilization of large amounts of fly ash as blended cement instead of disposing of it as a waste. Cement blended with fly ash is also required as a countermeasure to reduce the amount of CO{sub 2} generation. In this study, the influences of the glass content and the basicity of glass phase on the hydration of fly ash cement were clarified and hydration over a long curing time was characterized. Two kinds of fly ash with different glass content, one with 38.2% and another with 76.6%, were used. The hydration ratio of fly ash was increased by increasing the glass content in fly ash in the specimens cured for 270 days. When the glass content of fly ash is low, the basicity of glass phase tends to decrease. Reactivity of fly ash is controlled by the basicity of the glass phase in fly ash during a period from 28 to 270 days. However, at an age of 360 days, the reaction ratios of fly ash show almost identical values with different glass contents. Fly ash also affected the hydration of cement clinker minerals in fly ash cement. While the hydration of alite was accelerated, that of belite was retarded at a late stage.

  6. Comparison of stromal hydration techniques for clear corneal cataract incisions: conventional hydration versus anterior stromal pocket hydration.

    Science.gov (United States)

    Mifflin, Mark D; Kinard, Krista; Neuffer, Marcus C

    2012-06-01

    Anterior stromal pocket hydration was compared with conventional hydration for preventing wound leak after 2.8 mm uniplanar clear corneal incisions (CCIs) in patients having routine cataract surgery. Conventional hydration involves hydration of the lateral walls of the main incision with visible whitening of the stroma. The anterior stromal pocket hydration technique involves creation of an additional supraincisional stromal pocket overlying the main incision, which is then hydrated instead of the main incision. Sixty-six eyes of 48 patients were included in the data analysis with 33 assigned to each study group. The anterior stromal pocket hydration technique was significantly better than conventional hydration in preventing wound leak due to direct pressure on the posterior lip of the incision. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  7. Gas hydrates forming and decomposition conditions analysis

    Directory of Open Access Journals (Sweden)

    А. М. Павленко

    2017-07-01

    Full Text Available The concept of gas hydrates has been defined; their brief description has been given; factors that affect the formation and decomposition of the hydrates have been reported; their distribution, structure and thermodynamic conditions determining the gas hydrates formation disposition in gas pipelines have been considered. Advantages and disadvantages of the known methods for removing gas hydrate plugs in the pipeline have been analyzed, the necessity of their further studies has been proved. In addition to the negative impact on the process of gas extraction, the hydrates properties make it possible to outline the following possible fields of their industrial use: obtaining ultrahigh pressures in confined spaces at the hydrate decomposition; separating hydrocarbon mixtures by successive transfer of individual components through the hydrate given the mode; obtaining cold due to heat absorption at the hydrate decomposition; elimination of the open gas fountain by means of hydrate plugs in the bore hole of the gushing gasser; seawater desalination, based on the hydrate ability to only bind water molecules into the solid state; wastewater purification; gas storage in the hydrate state; dispersion of high temperature fog and clouds by means of hydrates; water-hydrates emulsion injection into the productive strata to raise the oil recovery factor; obtaining cold in the gas processing to cool the gas, etc.

  8. Hydration of highly charged ions.

    Science.gov (United States)

    Hofer, Thomas S; Weiss, Alexander K H; Randolf, Bernhard R; Rode, Bernd M

    2011-08-01

    Based on a series of ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulations, the broad spectrum of structural and dynamical properties of hydrates of trivalent and tetravalent ions is presented, ranging from extreme inertness to immediate hydrolysis. Main group and transition metal ions representative for different parts of the periodic system are treated, as are 2 threefold negatively charged anions. The results show that simple predictions of the properties of the hydrates appear impossible and that an accurate quantum mechanical simulation in cooperation with sophisticated experimental investigations seems the only way to obtain conclusive results.

  9. Great Market Potential of Hydrazine Hydrate

    Institute of Scientific and Technical Information of China (English)

    Shi Yuying

    2007-01-01

    @@ Stable consumption growth worldwide Hydrazine hydrate is an organic chemical raw material with extensive applications. The world's capacity to produce hydrazine hydrate has reached more than 200 thousand t/atoday (based on 100% hydrazine content).

  10. Methods to determine hydration states of minerals and cement hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Baquerizo, Luis G., E-mail: luis.baquerizoibarra@holcim.com [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Matschei, Thomas [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Scrivener, Karen L. [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Saeidpour, Mahsa; Thorell, Alva; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)

    2014-11-15

    This paper describes a novel approach to the quantitative investigation of the impact of varying relative humidity (RH) and temperature on the structure and thermodynamic properties of salts and crystalline cement hydrates in different hydration states (i.e. varying molar water contents). The multi-method approach developed here is capable of deriving physico-chemical boundary conditions and the thermodynamic properties of hydrated phases, many of which are currently missing from or insufficiently reported in the literature. As an example the approach was applied to monosulfoaluminate, a phase typically found in hydrated cement pastes. New data on the dehydration and rehydration of monosulfoaluminate are presented. Some of the methods used were validated with the system Na{sub 2}SO{sub 4}–H{sub 2}O and new data related to the absorption of water by anhydrous sodium sulfate are presented. The methodology and data reported here should permit better modeling of the volume stability of cementitious systems exposed to various different climatic conditions.

  11. Novel understanding of calcium silicate hydrate from dilute hydration

    KAUST Repository

    Zhang, Lina

    2017-05-13

    The perspective of calcium silicate hydrate (C-S-H) is still confronting various debates due to its intrinsic complicated structure and properties after decades of studies. In this study, hydration at dilute suspension of w/s equaling to 10 was conducted for tricalcium silicate (C3S) to interpret long-term hydration process and investigate the formation, structure and properties of C-S-H. Based on results from XRD, IR, SEM, NMR and so forth, loose and dense clusters of C-S-H with analogous C/S ratio were obtained along with the corresponding chemical formulae proposed as Ca5Si4O13∙6.2H2O. Crystalline structure inside C-S-H was observed by TEM, which was allocated at the foil-like proportion as well as the edge of wrinkles of the product. The long-term hydration process of C3S in dilute suspension could be sketchily described as migration of calcium hydroxide and in-situ growth of C-S-H with equilibrium silicon in aqueous solution relatively constant and calcium varied.

  12. Influenza Vaccine, Inactivated or Recombinant

    Science.gov (United States)

    ... die from flu, and many more are hospitalized.Flu vaccine can:keep you from getting flu, make flu ... inactivated or recombinant influenza vaccine?A dose of flu vaccine is recommended every flu season. Children 6 months ...

  13. Molecular Dynamics Modeling of Hydrated Calcium-Silicate-Hydrate (CSH) Cement Molecular Structure

    Science.gov (United States)

    2014-08-30

    properties of key hydrated cement constituent calcium-silicate-hydrate (CSH) at the molecular, nanometer scale level. Due to complexity, still unknown...public release; distribution is unlimited. Molecular Dynamics Modeling of Hydrated Calcium-Silicate- Hydrate (CSH) Cement Molecular Structure The views... Cement Molecular Structure Report Title Multi-scale modeling of complex material systems requires starting from fundamental building blocks to

  14. Hydration and Thermal Expansion in Anatase Nanoparticles.

    Science.gov (United States)

    Zhu, He; Li, Qiang; Ren, Yang; Fan, Longlong; Chen, Jun; Deng, Jinxia; Xing, Xianran

    2016-08-01

    A tunable thermal expansion is reported in nanosized anatase by taking advantage of surface hydration. The coefficient of thermal expansion of 4 nm TiO2 along a-axis is negative with a hydrated surface and is positive without a hydrated surface. High-energy synchrotron X-ray pair distribution function analysis combined with ab initio calculations on the specific hydrated surface are carried out to reveal the local structure distortion that is responsible for the unusual negative thermal expansion.

  15. Hydration and Thermal Expansion in Anatase Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, He [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Li, Qiang [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Ren, Yang [Argonne National Laboratory, X-Ray Science Division, Argonne IL 60439 USA; Fan, Longlong [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Chen, Jun [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Deng, Jinxia [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Xing, Xianran [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China

    2016-06-06

    A tunable thermal expansion is reported in nanosized anatase by taking advantage of surface hydration. The coefficient of thermal expansion of 4 nm TiO2 along a-axis is negative with a hydrated surface and is positive without a hydrated surface. High-energy synchrotron X-ray pair distribution function analysis combined with ab initio calculations on the specific hydrated surface are carried out to reveal the local structure distortion that is responsible for the unusual negative thermal expansion.

  16. Diverse electron-induced optical emissions from space observatory materials at low temperatures

    Science.gov (United States)

    Dennison, J. R.; Evans Jensen, Amberly; Wilson, Gregory; Dekany, Justin; Bowers, Charles W.; Meloy, Robert

    2013-09-01

    Electron irradiation experiments have investigated the diverse electron-induced optical and electrical signatures observed in ground-based tests of various space observatory materials at low temperature. Three types of light emission were observed: (i); long-duration cathodoluminescence which persisted as long as the electron beam was on (ii) short-duration (polyimides, epoxy resins, and silica glasses) and composite dielectric materials (disordered SiO2 thin films, carbon- and fiberglass-epoxy composites, and macroscopically-conductive carbon-loaded polyimides). We conclude that electron-induced optical emissions resulting from interactions between observatory materials and the space environment electron flux can, in specific circumstances, make significant contributions to the stray light background that could possibly adversely affect the performance of space-based observatories.

  17. Terahertz sensing of corneal hydration.

    Science.gov (United States)

    Singh, Rahul S; Tewari, Priyamvada; Bourges, Jean Louis; Hubschman, Jean Pierre; Bennett, David B; Taylor, Zachary D; Lee, H; Brown, Elliott R; Grundfest, Warren S; Culjat, Martin O

    2010-01-01

    An indicator of ocular health is the hydrodyanmics of the cornea. Many corneal disorders deteriorate sight as they upset the normal hydrodynamics of the cornea. The mechanisms include the loss of endothelial pump function of corneal dystophies, swelling and immune response of corneal graft rejection, and inflammation and edema, which accompany trauma, burn, and irritation events. Due to high sensitivity to changes of water content in materials, a reflective terahertz (300 GHz and 3 THz) imaging system could be an ideal tool to measure the hydration level of the cornea. This paper presents the application of THz technology to visualize the hydration content across ex vivo porcine corneas. The corneas, with a thickness variation from 470 - 940 µm, were successfully imaged using a reflective pulsed THz imaging system, with a maximum SNR of 50 dB. To our knowledge, no prior studies have reported on the use of THz in measuring hydration in corneal tissues or other ocular tissues. These preliminary findings indicate that THz can be used to accurately sense hydration levels in the cornea using a pulsed, reflective THz imaging system.

  18. Physical properties of gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Kliner, J.T.R.; Grozic, J.L.H. [Calgary Univ., AB (Canada)

    2003-07-01

    Gas hydrates are naturally occurring, solid crystalline compounds (clathrates) that encapsulate gas molecules inside the lattices of hydrogen bonded water molecules within a specific temperature-pressure stability zone. Estimates of the total quantity of available methane gas in natural occurring hydrates are based on twice the energy content of known conventional fossil fuels reservoirs. Accurate and reliable in-situ quantification techniques are essential in determining the economic viability of this potential energy yield, which is dependent upon several factors such as sensitivity of the temperature-pressure stability zone, sediment type, porosity, permeability, concentration/abundance of free gas, spatial distribution in pore spaces, specific cage occupancy, and the influence of inhibitors. Various techniques like acoustic P and S waves, time domain reflectometry, and electrical resistance have been used to analyze the quantity and spatial distribution of the gas hydrate samples. These techniques were reviewed and the results obtained in the course of gas hydrate research were presented. 34 refs., 8 figs.

  19. Hydration kinetics of transgenic soybeans

    Directory of Open Access Journals (Sweden)

    Aline Francielle Fracasso

    2015-01-01

    Full Text Available The kinetic and experimental analyses of the hydration process of transgenic soybeans (BRS 225 RR are provided. The importance of the hydration process consists of the grain texture modifications which favor grinding and extraction of soybeans. The soaking isotherms were obtained for four different temperatures. Results showed that temperature affected transgenic soybeans´ hydration rate and time. Moisture content d.b. of the soybeans increased from 0.12 ± 0.01 kg kg-1 to 1.45 ± 0.19 kg kg-1 during 270 min. of process. Two models were used to fit the kinetic curves: an empirical model developed by Peleg (1988 and a phenomenological one, proposed by Omoto et al. (2009. The two models adequately represented the hydration kinetics. Peleg model was applied to the experimental data and the corresponding parameters were obtained and correlated to temperature. The model by Omoto et al. (2009 showed a better statistical fitting. Although Ks was affected by temperature (Ks = 0.38079 exp (-2289.3 T-1, the equilibrium concentration remained practically unchanged.

  20. Electron-induced dry reforming of methane in a temperature-controlled dielectric barrier discharge reactor

    KAUST Repository

    Zhang, Xuming

    2013-09-23

    Dry reforming of methane has the potential to reduce the greenhouse gases methane and carbon dioxide and to generate hydrogen-rich syngas. In reforming methane, plasma-assisted reforming processes may have advantages over catalytic processes because they are free from coking and their response time for mobile applications is quick. Although plasma-assisted reforming techniques have seen recent developments, systematic studies that clarify the roles that electron-induced chemistry and thermo-chemistry play are needed for a full understanding of the mechanisms of plasma-assisted reformation. Here, we developed a temperature-controlled coaxial dielectric barrier discharge (DBD) apparatus to investigate the relative importance of electron-induced chemistry and thermo-chemistry in dry reforming of methane. In the tested background temperature range 297-773 K, electron-induced chemistry, as characterized by the physical properties of micro-discharges, was found to govern the conversions of CH4 and CO2, while thermo-chemistry influenced the product selectivities because they were found to depend on the background temperature. Comparisons with results from arc-jet reformation indicated that thermo-chemistry is an efficient conversion method. Our findings may improve designs of plasma-assisted reformers by using relatively hotter plasma sources. However, detailed chemical kinetic studies are needed. © 2013 IOP Publishing Ltd.

  1. Physical activity, hydration and health

    Directory of Open Access Journals (Sweden)

    Ascensión Marcos

    2014-06-01

    Full Text Available Since the beginning of mankind, man has sought ways to promote and preserve health as well as to prevent disease. Hydration, physical activity and exercise are key factors for enhancing human health. However, either a little dose of them or an excess can be harmful for health maintenance at any age. Water is an essential nutrient for human body and a major key to survival has been to prevent dehydration. However, there is still a general controversy regarding the necessary amount to drink water or other beverages to properly get an adequate level of hydration. In addition, up to now the tools used to measure hydration are controversial. To this end, there are several important groups of variables to take into account such as water balance, hydration biomarkers and total body water. A combination of methods will be the most preferred tool to find out any risk or situation of dehydration at any age range. On the other hand, physical activity and exercise are being demonstrated to promote health, avoiding or reducing health problems, vascular and inflammatory diseases and helping weight management. Therefore, physical activity is also being used as a pill within a therapy to promote health and reduce risk diseases, but as in the case of drugs, dose, intensity, frequency, duration and precautions have to be evaluated and taken into account in order to get the maximum effectiveness and success of a treatment. On the other hand, sedentariness is the opposite concept to physical activity that has been recently recognized as an important factor of lifestyle involved in the obesogenic environment and consequently in the risk of the non-communicable diseases. In view of the literature consulted and taking into account the expertise of the authors, in this review a Decalogue of global recommendations is included to achieve an adequate hydration and physical activity status to avoid overweight/obesity consequences.

  2. Seismic reflections associated with submarine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Andreassen, K.

    1995-12-31

    Gas hydrates are often suggested as a future energy resource. This doctoral thesis improves the understanding of the concentration and distribution of natural submarine gas hydrates. The presence of these hydrates are commonly inferred from strong bottom simulating reflection (BSR). To investigate the nature of BSR, this work uses seismic studies of hydrate-related BSRs at two different locations, one where gas hydrates are accepted to exist and interpreted to be very extensive (in the Beaufort Sea), the other with good velocity data and downhole logs available (offshore Oregon). To ascertain the presence of free gas under the BSR, prestack offset data must supplement near-vertical incidence seismic data. A tentative model for physical properties of sediments partially saturated with gas hydrate and free gas is presented. This model, together with drilling information and seismic data containing the BSR beneath the Oregon margin and the Beaufort Sea, made it possible to better understand when to apply the amplitude-versus-offset (AVO) method to constrain BSR gas hydrate and gas models. Distribution of natural gas hydrates offshore Norway and Svalbard is discussed and interpreted as reflections from the base of gas hydrate-bearing sediments, overlying sediments containing free gas. Gas hydrates inferred to exist at the Norwegian-Svalbard continental margin correlate well with Cenozoic depocenters, and the associated gas is assumed to be mainly biogenic. Parts of that margin have a high potential for natural gas hydrates of both biogenic and thermogenic origin. 235 refs., 86 figs., 4 tabs.

  3. Handbook of gas hydrate properties and occurrence

    Energy Technology Data Exchange (ETDEWEB)

    Kuustraa, V.A.; Hammershaimb, E.C.

    1983-12-01

    This handbook provides data on the resource potential of naturally occurring hydrates, the properties that are needed to evaluate their recovery, and their production potential. The first two chapters give data on the naturally occurring hydrate potential by reviewing published resource estimates and the known and inferred occurrences. The third and fourth chapters review the physical and thermodynamic properties of hydrates, respectively. The thermodynamic properties of hydrates that are discussed include dissociation energies and a simplified method to calculate them; phase diagrams for simple and multi-component gases; the thermal conductivity; and the kinetics of hydrate dissociation. The final chapter evaluates the net energy balance of recovering hydrates and shows that a substantial positive energy balance can theoretically be achieved. The Appendices of the Handbook summarize physical and thermodynamic properties of gases, liquids and solids that can be used in designing and evaluating recovery processes of hydrates. 158 references, 67 figures, 47 tables.

  4. Separation of water through gas hydrate formation

    DEFF Research Database (Denmark)

    Boch Andersen, Torben; Thomsen, Kaj

    2009-01-01

    Gas hydrate is normally recognized as a troublemaker in the oil and gas industry. However, gas hydrate has some interesting possibilities when used in connection with separation of water. Nordic Sugar has investigated the possibility of using gas hydrates for concentration of sugar juice. The goa...... volumes and the needs for high pressure. The process could be interesting for concentration of heat sensitive, high value products......Gas hydrate is normally recognized as a troublemaker in the oil and gas industry. However, gas hydrate has some interesting possibilities when used in connection with separation of water. Nordic Sugar has investigated the possibility of using gas hydrates for concentration of sugar juice. The goal...... of the project was to formulate an alternative separation concept, which can replace the traditional water evaporation process in the sugar production. Work with the separation concept showed that gas hydrates can be used for water separation. The process is not suitable for sugar production because of large...

  5. Well log characterization of natural gas hydrates

    Science.gov (United States)

    Collett, Timothy S.; Lee, Myung W.

    2011-01-01

    In the last 25 years we have seen significant advancements in the use of downhole well logging tools to acquire detailed information on the occurrence of gas hydrate in nature: From an early start of using wireline electrical resistivity and acoustic logs to identify gas hydrate occurrences in wells drilled in Arctic permafrost environments to today where wireline and advanced logging-while-drilling tools are routinely used to examine the petrophysical nature of gas hydrate reservoirs and the distribution and concentration of gas hydrates within various complex reservoir systems. The most established and well known use of downhole log data in gas hydrate research is the use of electrical resistivity and acoustic velocity data (both compressional- and shear-wave data) to make estimates of gas hydrate content (i.e., reservoir saturations) in various sediment types and geologic settings. New downhole logging tools designed to make directionally oriented acoustic and propagation resistivity log measurements have provided the data needed to analyze the acoustic and electrical anisotropic properties of both highly inter-bedded and fracture dominated gas hydrate reservoirs. Advancements in nuclear-magnetic-resonance (NMR) logging and wireline formation testing have also allowed for the characterization of gas hydrate at the pore scale. Integrated NMR and formation testing studies from northern Canada and Alaska have yielded valuable insight into how gas hydrates are physically distributed in sediments and the occurrence and nature of pore fluids (i.e., free-water along with clay and capillary bound water) in gas-hydrate-bearing reservoirs. Information on the distribution of gas hydrate at the pore scale has provided invaluable insight on the mechanisms controlling the formation and occurrence of gas hydrate in nature along with data on gas hydrate reservoir properties (i.e., permeabilities) needed to accurately predict gas production rates for various gas hydrate

  6. Thermal conductivity of hydrate-bearing sediments

    Science.gov (United States)

    Cortes, Douglas D.; Martin, Ana I.; Yun, Tae Sup; Francisca, Franco M.; Santamarina, J. Carlos; Ruppel, Carolyn

    2009-11-01

    A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate-bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces.

  7. Thermal conductivity of hydrate-bearing sediments

    Science.gov (United States)

    Cortes, D.D.; Martin, A.I.; Yun, T.S.; Francisca, F.M.; Santamarina, J.C.; Ruppel, C.

    2009-01-01

    A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate-bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces. Copyright 2009 by the American Geophysical Union.

  8. The effect of hydrate saturation on water retention curves in hydrate-bearing sediments

    Science.gov (United States)

    Mahabadi, Nariman; Zheng, Xianglei; Jang, Jaewon

    2016-05-01

    The experimental measurement of water retention curve in hydrate-bearing sediments is critically important to understand the behavior of hydrate dissociation and gas production. In this study, tetrahydrofuran (THF) is selected as hydrate former. The pore habit of THF hydrates is investigated by visual observation in a transparent micromodel. It is confirmed that THF hydrates are not wetting phase on the quartz surface of the micromodel and occupy either an entire pore or part of pore space resulting in change in pore size distribution. And the measurement of water retention curves in THF hydrate-bearing sediments with hydrate saturation ranging from Sh = 0 to Sh = 0.7 is conducted for excess water condition. The experimental results show that the gas entry pressure and the capillary pressure increase with increasing hydrate saturation. Based on the experimental results, fitting parameters for van Genuchten equation are suggested for different hydrate saturation conditions.

  9. Synthesis of hydrated lutetium carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Song Liu [South China Univ. of Technology, Dept. of Applied Chemistry, Guangdong (China); Rong-jun Ma [Changsha Research Institute of Minig and Metallurgy, Hunan (China)

    1997-09-01

    Crystalline lutetium carbonate was synthesized for the corresponding chloride using ammonium bicarbonate as precipitant. The chemical analyses suggest that the synthesized lutetium carbonate is a hydrated basic carbonate or oxycarbonate. The X-ray powder diffraction data are presented. The IR data for the compound show the presence of two different carbonate groups. There is no stable intermediate carbonate in the process of thermal decomposition of the lutetium carbonate. (au) 15 refs.

  10. Crystallite size distributions of marine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Klapp, S.A.; Bohrmann, G.; Abegg, F. [Bremen Univ., Bremen (Germany). Research Center of Ocean Margins; Hemes, S.; Klein, H.; Kuhs, W.F. [Gottingen Univ., Gottingen (Germany). Dept. of Crystallography

    2008-07-01

    Experimental studies were conducted to determine the crystallite size distributions of natural gas hydrate samples retrieved from the Gulf of Mexico, the Black Sea, and a hydrate ridge located near offshore Oregon. Synchrotron radiation technology was used to provide the high photon fluxes and high penetration depths needed to accurately analyze the bulk sediment samples. A new beam collimation diffraction technique was used to measure gas hydrate crystallite sizes. The analyses showed that gas hydrate crystals were globular in shape. Mean crystallite sizes ranged from 200 to 400 {mu}m for hydrate samples taken from the sea floor. Larger grain sizes in the hydrate ridge samples suggested differences in hydrate formation ages or processes. A comparison with laboratory-produced methane hydrate samples showed half a lognormal curve with a mean value of 40{mu}m. Results of the study showed that a cautious approach must be adopted when transposing crystallite-size sensitive physical data from laboratory-made gas hydrates to natural settings. It was concluded that crystallite size information may also be used to resolve the formation ages of gas hydrates when formation processes and conditions are constrained. 48 refs., 1 tab., 9 figs.

  11. IMPORTANCE OF HYDRATION IN SPORTS

    Directory of Open Access Journals (Sweden)

    Goran Vasić

    2008-08-01

    Full Text Available Importance of hydration is detrmined by importance of functions of water in the human organism: i.e. regulation of body temperature, transport, excretion of waste materials through urine, digestion of food which is facilititated by saliva and gastric juices, maintenance of flexibility of organs and tissues About 60 % body mass of an adult person (males: 61 %, females: 54 % is made up of water. Water content of a newly born baby reaches 77 %, and it is up to 50 % in adults. It is very important for sportsmen to provide adequate hydration during and after the time of bodily activities. A symptom of water shortage is thirst. However, thirst is a late response of an organism and it occurs when dehydration has already taken place. Minimum in take of fluids in humans should range between one-and-half to two liters. It has been known for a long time that there is no success in sport without proper hydration in a sportsman.

  12. High gas pressure: an innovative method for the inactivation of dried bacterial spores.

    Science.gov (United States)

    Colas de la Noue, A; Espinasse, V; Perrier-Cornet, J-M; Gervais, P

    2012-08-01

    In this article, an original non-thermal process to inactivate dehydrated bacterial spores is described. The use of gases such as nitrogen or argon as transmission media under high isostatic pressure led to an inactivation of over 2 logs CFU/g of Bacillus subtilis spores at 430 MPa, room temperature, for a 1 min treatment. A major requirement for the effectiveness of the process resided in the highly dehydrated state of the spores. Only a water activity below 0.3 led to substantial inactivation. The solubility of the gas in the lipid components of the spore and its diffusion properties was essential to inactivation. The main phenomenon involved seems to be the sorption of the gas under pressure by the spores' structures such as residual pores and plasma membranes, followed by a sudden drop in pressure. Observation by phase-contrast microscopy suggests that internal structures have been affected by the treatment. Some parallels with polymer permeability to gas and rigidity at various water activities offer a few clues about the behavior of the outer layers of spores in response to this parameter and provide a good explanation for the sensitivity of spores to high gas pressure discharge at low hydration levels. Specificity of microorganisms such as size, organization, and composition could help in understanding the differences between spores and yeast regarding the parameters required for inactivation, such as pressure or maintenance time.

  13. Study of Formation Mechanisms of Gas Hydrate

    Science.gov (United States)

    Yang, Jia-Sheng; Wu, Cheng-Yueh; Hsieh, Bieng-Zih

    2015-04-01

    Gas hydrates, which had been found in subsurface geological environments of deep-sea sediments and permafrost regions, are solid crystalline compounds of gas molecules and water. The estimated energy resources of hydrates are at least twice of that of the conventional fossil fuel in the world. Gas hydrates have a great opportunity to become a dominating future energy. In the past years, many laboratory experiments had been conducted to study chemical and thermodynamic characteristics of gas hydrates in order to investigate the formation and dissociation mechanisms of hydrates. However, it is difficult to observe the formation and dissociation of hydrates in a porous media from a physical experiment directly. The purpose of this study was to model the dynamic formation mechanisms of gas hydrate in porous media by reservoir simulation. Two models were designed for this study: 1) a closed-system static model with separated gas and water zones; this model was a hydrate equilibrium model to investigate the behavior of the formation of hydrates near the initial gas-water contact; and 2) an open-system dynamic model with a continuous bottom-up gas flow; this model simulated the behavior of gas migration and studied the formation of hydrates from flowed gas and static formation water in porous media. A phase behavior module was developed in this study for reservoir simulator to model the pressure-volume-temperature (PVT) behavior of hydrates. The thermodynamic equilibriums and chemical reactions were coupled with the phase behavior module to have functions modelling the formation and dissociation of hydrates from/to water and gas. The simulation models used in this study were validated from the code-comparison project proposed by the NETL. According to the modelling results of the closed-system static model, we found that predominated location for the formation of hydrates was below the gas-water contact (or at the top of water zone). The maximum hydrate saturation

  14. SEISMIC STUDIES OF MARINE GAS HYDRATES

    Institute of Scientific and Technical Information of China (English)

    SONG Haibin

    2003-01-01

    We give a brief introduction of developments of seismic methods in the studies of marine gas hydrates. Then we give an example of seismic data processing for BSRs in western Nankai accretionary prism, a typical gas hydrate distribution region. Seismic data processing is proved to be important to obtain better images of BSRs distribution. Studies of velocity structure of hydrated sediments are useful for better understanding the distribution of gas hydrates. Using full waveform inversion, we successfully derived high-resolution velocity model of a double BSR in eastern Nankai Trough area. Recent survey and research show that gas hydrates occur in the marine sediments of the South China Sea and East China Sea.But we would like to say seismic researches on gas hydrate in China are very preliminary.

  15. Development of Alaskan gas hydrate resources

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, V.A.; Sharma, G.D.; Patil, S.L.

    1991-06-01

    The research undertaken in this project pertains to study of various techniques for production of natural gas from Alaskan gas hydrates such as, depressurization, injection of hot water, steam, brine, methanol and ethylene glycol solutions through experimental investigation of decomposition characteristics of hydrate cores. An experimental study has been conducted to measure the effective gas permeability changes as hydrates form in the sandpack and the results have been used to determine the reduction in the effective gas permeability of the sandpack as a function of hydrate saturation. A user friendly, interactive, menu-driven, numerical difference simulator has been developed to model the dissociation of natural gas hydrates in porous media with variable thermal properties. A numerical, finite element simulator has been developed to model the dissociation of hydrates during hot water injection process.

  16. Terahertz Time Domain Spectroscopy for Structure-II Gas Hydrates

    DEFF Research Database (Denmark)

    Takeya, Kei; Zhang, Caihong; Kawayama, Iwao

    2009-01-01

    For the nondestructive inspection of gas hydrates, terahertz (THz) time-domain spectroscopy (TDS) was applied to tetrahydrofuran (THF) hydrate and propane hydrate. The absorption of propane hydrate monotonically increases with frequency, similar to the case of ice, while THF hydrate has a charact...

  17. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    1998-01-01

    This report deals with gas phase hydration of pure cement clinker minerals at reduced relative humidities. This is an important subject in relation to modern high performance concrete which may self-desiccate during hydration. In addition the subject has relevance to storage stability where...... prehydration may occur. In the report both theoretical considerations and experimental data are presented. It is suggested that the initiation of hydration during water vapour exposure is nucleation controlled....

  18. PP-EPDM thermoplastic vulcanisates (TPVs by electron induced reactive processing

    Directory of Open Access Journals (Sweden)

    2009-11-01

    Full Text Available Reactive processing combines melt mixing process and chemical reaction simultaneously. TPVs are produced by such reactive processing. Polymer modification with high energy electrons is based on generation of excited atoms or molecules and ions for subsequent molecular changes via radical induced chemical reactions. In the present study, electron induced reactive processing is used for the development of TPVs. A 1.5 MeV electron accelerator was directly coupled to an internal mixer in order to induce chemical reactions by energy input via high energy electrons under dynamic conditions of melt mixing of polypropylene (PP and ethylene propylene diene monomer rubber (EPDM. The influence of absorbed dose (25 to 100 kGy as well as electron energy (1.5 and 0.6 MeV and electron treatment time (15 to 60 s have been studied. Increased values of both tensile strength and elongation at break of the TPVs indicate in-situ compatibilisation of PP and EPDM as well as cross-linking in the EPDM phase upon electron induced reactive processing. Dynamic mechanical analyses showed a decrease in value of glass transition temperature peak of EPDM in tangent delta curve with increasing dose. This also indicates higher degree of cross-linking in EPDM phase, which is further supported by a gel content that is higher than the EPDM content itself in the blend.

  19. Prediction of Refrigerant Gas Hydrates Formation Conditions

    Institute of Scientific and Technical Information of China (English)

    Deqing Liang; Ruzhu Wang; Kaihua Guo; Shuanshi Fan

    2001-01-01

    A fugacity model was developed for prediction of mixed refrigerant gas hydrates formation conditions based on the molecule congregation and solution theories. In this model, g as hydrates were regarded as non-ideal solid solution composed of water groups and guest molecules, and the expressions of fugacity of guest molecules in hydrate phase was proposed accordingly. It has been shown that the developed model can indicate successfully the effect of guest-guest molecule interaction. The results showed that the model can describe better the characteristics of phase equilibrium of mixed refrigerant gas hydrates and predictions are in good agreement with experimental data.

  20. Desalination utilizing clathrate hydrates (LDRD final report).

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Blake Alexander; Bradshaw, Robert W.; Dedrick, Daniel E.; Cygan, Randall Timothy (Sandia National Laboratories, Albuquerque, NM); Greathouse, Jeffery A. (Sandia National Laboratories, Albuquerque, NM); Majzoub, Eric H. (University of Missouri, Columbia, MO)

    2008-01-01

    Advances are reported in several aspects of clathrate hydrate desalination fundamentals necessary to develop an economical means to produce municipal quantities of potable water from seawater or brackish feedstock. These aspects include the following, (1) advances in defining the most promising systems design based on new types of hydrate guest molecules, (2) selection of optimal multi-phase reactors and separation arrangements, and, (3) applicability of an inert heat exchange fluid to moderate hydrate growth, control the morphology of the solid hydrate material formed, and facilitate separation of hydrate solids from concentrated brine. The rate of R141b hydrate formation was determined and found to depend only on the degree of supercooling. The rate of R141b hydrate formation in the presence of a heat exchange fluid depended on the degree of supercooling according to the same rate equation as pure R141b with secondary dependence on salinity. Experiments demonstrated that a perfluorocarbon heat exchange fluid assisted separation of R141b hydrates from brine. Preliminary experiments using the guest species, difluoromethane, showed that hydrate formation rates were substantial at temperatures up to at least 12 C and demonstrated partial separation of water from brine. We present a detailed molecular picture of the structure and dynamics of R141b guest molecules within water cages, obtained from ab initio calculations, molecular dynamics simulations, and Raman spectroscopy. Density functional theory calculations were used to provide an energetic and molecular orbital description of R141b stability in both large and small cages in a structure II hydrate. Additionally, the hydrate of an isomer, 1,2-dichloro-1-fluoroethane, does not form at ambient conditions because of extensive overlap of electron density between guest and host. Classical molecular dynamics simulations and laboratory trials support the results for the isomer hydrate. Molecular dynamics simulations

  1. Waters of Hydration of Cupric Hydrates: A Comparison between Heating and Absorbance Methods

    Science.gov (United States)

    Barlag, Rebecca; Nyasulu, Frazier

    2011-01-01

    The empirical formulas of four cupric hydrates are determined by measuring the absorbance in aqueous solution. The Beer-Lambert Law is verified by constructing a calibration curve of absorbance versus known Cu[superscript 2+](aq) concentration. A solution of the unknown hydrate is prepared by using 0.2-0.3 g of hydrate, and water is added such…

  2. Hydration in soccer: a review

    Directory of Open Access Journals (Sweden)

    Monteiro Cristiano Ralo

    2003-01-01

    Full Text Available Hydration should be considered before, during and after the exercise. This review intends to approach the main points of hydration process in soccer. The replacement of fluids during exercise is proportional to some factors, such as: exercise intensity; climatic conditions; the athlete's acclimatization; the athlete's physical conditioning; physiologic individual characteristics and the player's biomechanics. Performance is improved when players ingest not only water but also carbohydrate. The rates that carbohydrate and water are absorbed by the organism are limited by the rates of gastric emptying and intestinal absorption. The composition of drinks offered to the players should be influenced by the relative importance of the need of supplying carbohydrates or water; it should be remembered that the depletion of carbohydrate can result in fatigue and decrease of performance, but it is not usually a life-threatening condition. The addition of carbohydrate in these drinks increases the concentrations of blood glucose, increases the use of external fuel through the increase of the glucose oxidation in the muscles and it spares muscle glycogen. So, the ingestion of carbohydrate before and during the exercise can delay the emergence of fatigue and increase the players' performance. Several tactics can be used to avoid dehydration, like hyperhydration before exercise and player's acclimatization. The ideal situation to restore the player's fluid losses is between the sessions of exercises. Since soccer is a sport with quite peculiar characteristics related to hydration, the players should be concerned and educated about the importance of fluid ingestion before, during and after the exercise.

  3. Hydration behaviour of polyhydroxylated fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Zavala, J G [Departamento de Ciencias Exactas y Tecnologicas, Centro Universitario de Los Lagos, Universidad de Guadalajara, Enrique Diaz de Leon S/N, 47460 Jalisco (Mexico); Barajas-Barraza, R E [Departamento de Matematicas y Fisica, Instituto Tecnologico y de Estudios Superiores de Occidente, Periferico Sur, Manuel Gomez MorIn No 8585, 45604 Jalisco (Mexico); Padilla-Osuna, I; Guirado-Lopez, R A, E-mail: jgrz@culagos.udg.mx, E-mail: ebarajas@iteso.mx, E-mail: ismael@ifisica.uaslp.mx, E-mail: guirado@ifisica.uaslp.mx [Instituto de Fisica ' Manuel Sandoval Vallarta' , Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi (Mexico)

    2011-10-28

    We have performed semi-empirical as well as density functional theory calculations in order to analyse the hydration properties of both bare C{sub 60} and highly hydroxylated C{sub 60}(OH){sub 26} fullerenes. In all of our calculations, a total of 42 and 98 water molecules are always surrounding our here-considered carbon nanostructures. We found different wetting properties as a function of the chemical composition and structure of the OH-molecular over-layer covering the fullerene surface. In the case of bare C{sub 60}, water adsorption reveals that the H{sub 2}O species are not uniformly arranged around the carbon network but rather forms water droplets of different sizes, clearly revealing the hydrophobic nature of the C{sub 60} structure. In contrast, in the polyhydroxylated C{sub 60}(OH){sub 26} fullerenes, the degree of wetting is strongly influenced by the precise location of the hydroxyl groups. We found that different adsorbed configurations for the OH-molecular coating can lead to the formation of partially hydrated or completely covered C{sub 60}(OH){sub 26} compounds, a result that could be used to synthesize fullerene materials with different degrees of wettability. By comparing the relative stability of our hydroxylated structures in both bare and hydrated conditions we obtain that the energy ordering of the C{sub 60}(OH){sub 26} isomers can change in the presence of water. The radial distribution function of our hydrated fullerenes reveals that water near these kinds of surfaces is densely packed. In fact, by counting the number of H{sub 2}O molecules which are adsorbed, by means of hydrogen bonds, to the surface of our more stable C{sub 60}(OH){sub 26} isomer, we found that it varies in the range of 5-10, in good agreement with experiments. Finally, by comparing the calculated optical absorption spectra of various C{sub 60}(OH){sub 26} structures in the presence and absence of water molecules, we note that only slight variations in the position and

  4. Protein dynamics: hydration and cavities

    Directory of Open Access Journals (Sweden)

    K. Heremans

    2005-08-01

    Full Text Available The temperature-pressure behavior of proteins seems to be unique among the biological macromolecules. Thermodynamic as well as kinetic data show the typical elliptical stability diagram. This may be extended by assuming that the unfolded state gives rise to volume and enthalpy-driven liquid-liquid transitions. A molecular interpretation follows from the temperature and the pressure dependence of the hydration and cavities. We suggest that positron annihilation spectroscopy can provide additional quantitative evidence for the contributions of cavities to the dynamics of proteins. Only mature amyloid fibrils that form from unfolded proteins are very resistant to pressure treatment.

  5. Formation rate of natural gas hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Mork, Marit

    2002-07-01

    The rate of methane hydrate and natural gas hydrate formation was measured in a 9.5 litre stirred tank reactor of standard design. The experiments were performed to better understand the performance and scale-up of a reactor for continuous production of natural gas hydrates. The hydrate formation rate was measured at steady-state conditions at pressures between 70 and 90 bar and temperatures between 7 and 15 deg C. Between 44 and 56 % of the gas continuously supplied to the reactor was converted to hydrate. The experimental results show that the rate of hydrate formation is strongly influenced by gas injection rate and pressure. The effect of stirring rate is less significant and subcooling has no observable effect on the formation rate. Hydrate crystal concentration and gas composition do not influence the hydrate formation rate. Observations of produced hydrate crystals indicate that the crystals are elongated, about 5 micron in diameter and 10 micron long. Analysis of the results shows that the rate of hydrate formation is dominated by gas-liquid mass transfer. A mass transfer model, the bubble-to-crystal model, was developed for the hydrate formation rate in a continuous stirred tank reactor, given in terms of concentration driving force and an overall mass transfer coefficient. The driving force is the difference between the gas concentration at the gas-liquid interface and at the hydrate crystal surface. These concentrations correspond to the solubility of gas in water at experimental temperature and pressure and the solubility of gas at hydrate equilibrium temperature and experimental pressure, respectively. The overall mass transfer coefficient is expressed in terms of superficial gas velocity and impeller power consumption, parameters commonly used in study of stirred tank reactors. Experiments and modeling show that the stirred tank reactor has a considerable potential for increased production capacity. However, at higher hydrate production rates the

  6. Reductive defluorination of perfluorooctanoic acid by hydrated electrons in a sulfite-mediated UV photochemical system

    Energy Technology Data Exchange (ETDEWEB)

    Song, Zhou [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan 430074 (China); College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Tang, Heqing, E-mail: tangheqing@mail.scuec.edu.cn [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan 430074 (China); Wang, Nan, E-mail: nwang83@sina.com [College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhu, Lihua [College of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-11-15

    Highlights: • A new reductive method for PFOA defluorination was established by sulfite-mediated photolysis. • The defluorination of PFOA was dependent on sulfite concentration and solution pH. • A defluorination ratio of PFOA as high as 88.5% was achieved after reaction of 24 h. • A few of perfluorinated sulfonates were detected as intermediates during the degradation of PFOA. • A mechanism was proposed for the reductive defluorination of PFOA by hydrated electrons. -- Abstract: A method for reductive degradation of perfluorooctanoic acid (PFOA) was established by using a sulfite/UV process. This process led to a PFOA removal of 100% at about 1 h and a defluorination ratio of 88.5% at reaction time of 24 h under N{sub 2} atmosphere, whereas the use of either UV irradiation or SO{sub 3}{sup 2−} alone induced little defluorination of PFOA under the same conditions. It was confirmed that the reductive defluorination of PFOA was achieved by hydrated electrons being generated from the photo-conversion of SO{sub 3}{sup 2−} as a mediator. Theoretical reaction kinetic analysis demonstrated that the generation of hydrated electrons was promoted by increasing either SO{sub 3}{sup 2−} concentration or solution pH, leading to the acceleration of the PFOA defluorination. Accompanying the reduction of PFOA, a small amount of short-chain perfluorocarboxylic acids, less fluorinated carboxylic acids and perfluorinated alkyl sulfonates were generated, all of which were able to be further degraded with further releasing of fluoride ions. Based on the generation, accumulation and distribution of intermediates, hydrated electrons induced defluorination pathway of PFOA was proposed in a sulfite-mediated UV photochemical system.

  7. Bacterial inactivation of the anticancer drug doxorubicin.

    Science.gov (United States)

    Westman, Erin L; Canova, Marc J; Radhi, Inas J; Koteva, Kalinka; Kireeva, Inga; Waglechner, Nicholas; Wright, Gerard D

    2012-10-26

    Microbes are exposed to compounds produced by members of their ecological niche, including molecules with antibiotic or antineoplastic activities. As a result, even bacteria that do not produce such compounds can harbor the genetic machinery to inactivate or degrade these molecules. Here, we investigated environmental actinomycetes for their ability to inactivate doxorubicin, an aminoglycosylated anthracycline anticancer drug. One strain, Streptomyces WAC04685, inactivates doxorubicin via a deglycosylation mechanism. Activity-based purification of the enzymes responsible for drug inactivation identified the NADH dehydrogenase component of respiratory electron transport complex I, which was confirmed by gene inactivation studies. A mechanism where reduction of the quinone ring of the anthracycline by NADH dehydrogenase leads to deglycosylation is proposed. This work adds anticancer drug inactivation to the enzymatic inactivation portfolio of actinomycetes and offers possibilities for novel applications in drug detoxification. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Dynamics of a photoexcited hydrated electron

    NARCIS (Netherlands)

    Pshenichnikov, M.S.; Baltuška, A.; Wiersma, D.A.; Kärtner, F.X.

    2004-01-01

    Combining photon-echo and frequency-resolved pump-probe techniques with extremely short laser pulses that consist of only few optical cycles, we investigate the dynamics of the equilibrated hydrated electron. The pure dephasing time of the hydrated electron deduced from the photon-echo measurements

  9. Gas hydrate inhibition of drilling fluid additives

    Energy Technology Data Exchange (ETDEWEB)

    Xiaolan, L.; Baojiang, S.; Shaoran, R. [China Univ. of Petroleum, Dongying (China). Inst. of Petroleum Engineering

    2008-07-01

    Gas hydrates that form during offshore well drilling can have adverse impacts on well operational safety. The hydrates typically form in the risers and the annulus between the casing and the drillstring, and can stop the circulation of drilling fluids. In this study, experiments were conducted to measure the effect of drilling fluid additives on hydrate inhibition. Polyalcohols, well-stability control agents, lubricating agents, and polymeric materials were investigated in a stirred tank reactor at temperatures ranging from -10 degree C to 60 degrees C. Pressure, temperature, and torque were used to detect onset points of hydrate formation and dissociation. The inhibitive effect of the additives on hydrate formation was quantified. Phase boundary shifts were measured in terms of temperature difference or sub-cooling gained when chemicals were added to pure water. Results showed that the multiple hydroxyl groups in polyalcohol chemicals significantly inhibited hydrate formation. Polymeric and polyacrylamide materials had only a small impact on hydrate formation, while sulfonated methyl tannins were found to increase hydrate formation. 6 refs., 1 tab., 4 figs.

  10. Hydration shells exchange charge with their protein

    DEFF Research Database (Denmark)

    Abitan, Haim; Lindgård, Per-Anker; Nielsen, Bjørn Gilbert;

    2010-01-01

    Investigation of the interaction between a protein and its hydration shells is an experimental and theoretical challenge. Here, we used ultrasonic pressure waves in aqueous solutions of a protein to explore the conformational states of the protein and its interaction with its hydration shells. In...

  11. A new geotechnical gas hydrates research laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Grozic, J.L.H. [Calgary Univ., AB (Canada)

    2003-07-01

    Gas hydrates encapsulate natural gas molecules in a very compact form, as ice-like compounds composed of water molecules. Permafrost environments and offshore areas contain vast quantities of gas hydrates within soil and rock. This paper describes the role played by gas hydrates in submarine slope instability, their potential as a sustainable energy source, and their effects on global climate change. A new state-of-the-art laboratory located at the University of Calgary, which was developed to study the geomechanical behaviour of gas hydrate-sediment mixtures, was also presented. A specialized high pressure low temperature triaxial apparatus capable of performing a suite of tests on gas hydrate-sediment mixtures is housed in this laboratory. Extensive renovations were required in order to enable the use of methane gas to simulate natural hydrate formation conditions. The laboratory is specifically designed to examine the properties and behaviour of reconstituted gas hydrate-sediment mixtures and natural gas hydrate core samples. 26 refs., 9 figs.

  12. Investigations into surfactant/gas hydrate relationship

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Rudy; Zhang, Guochang; Dearman, Jennifer; Woods, Charles [Swalm School of Chemical Engineering, Mississippi State University, Mississippi State, MS 39762 (United States)

    2007-03-15

    Gas hydrates have unique physical properties portending useful industrial applications of gas storage, gas separation, or water desalination. When gas hydrates were found in the early 1990s to occur naturally and abundantly in seafloors, three other primary interests and concerns emerged: potential new energy source, climate threat from their greenhouse gases, and seafloor instabilities. This paper presents research showing how anionic synthetic surfactants helped develop an industrial gas hydrate storage process for natural gas and how naturally-occurring in-situ anionic biosurfactants influence the formation and placement of gas hydrates in ocean sediments. The catalytic effects, mechanisms, and surface specificities imparted by synthetic surfactants in the gas storage process and imparted by biosurfactants in porous media are discussed. The Bacillus subtilis bacterium that is indigenous to gas hydrate mounds in the Gulf of Mexico was cultured in the laboratory. Its biosurfactant was separated and found to catalyze gas hydrates in porous media. The experiments indicate that seafloor-biosurfactants can be produced rapidly in-situ to achieve threshold concentrations whereby hydrates are promoted. The biosurfactants accumulate and promote hydrate formation on specific mineral surfaces such as sodium montmorillonite. (author)

  13. Raman Spectroscopic Studies of Methane Gas Hydrates

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.

    2009-01-01

    A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory.......A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory....

  14. Inactivated Schmallenberg virus prototype vaccines.

    Science.gov (United States)

    Wernike, Kerstin; Nikolin, Veljko M; Hechinger, Silke; Hoffmann, Bernd; Beer, Martin

    2013-08-02

    Schmallenberg virus (SBV), a novel Orthobunyavirus, is an insect-transmitted pathogen and was first described in Europe in 2011. SBV causes a mild transient disease in adult ruminants, but severe foetal malformation and stillbirth were observed after an infection of naive cows and ewes, which is responsible for considerable economic losses. The virus is now widely distributed in Europe, and no vaccines were available to stop transmission and spread. In the present study, 16 calves and 25 sheep, the major target species of SBV infection, were vaccinated twice 3 weeks apart with one of 5 newly developed, inactivated vaccine candidates. Six calves and 5 sheep were kept as unvaccinated controls. All animals were clinically, serologically and virologically examined before and after challenge infection. Immunisation with the inactivated preparations resulted in a neutralising antibody response three weeks after the second vaccination without any side effects. The number of animals that seroconverted in each group and the strength of the antibody response were dependent on the cell line used for virus growth and on the viral titre prior to inactivation. Four vaccine prototypes completely prevented RNAemia after challenge infection, a fifth candidate reduced RNAemia considerably. Although further evaluations e.g. regarding duration of immunity will be necessary, the newly developed vaccines are promising candidates for the prevention of SBV-infection and could be a valuable tool in SBV control strategies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Hydrazine vapor inactivates Bacillus spores

    Science.gov (United States)

    Schubert, Wayne W.; Engler, Diane L.; Beaudet, Robert A.

    2016-05-01

    NASA policy restricts the total number of bacterial spores that can remain on a spacecraft traveling to any planetary body which might harbor life or have evidence of past life. Hydrazine, N2H4, is commonly used as a propellant on spacecraft. Hydrazine as a liquid is known to inactivate bacterial spores. We have now verified that hydrazine vapor also inactivates bacterial spores. After Bacillus atrophaeus ATCC 9372 spores deposited on stainless steel coupons were exposed to saturated hydrazine vapor in closed containers, the spores were recovered from the coupons, serially diluted, pour plated and the surviving bacterial colonies were counted. The exposure times required to reduce the spore population by a factor of ten, known as the D-value, were 4.70 ± 0.50 h at 25 °C and 2.85 ± 0.13 h at 35 °C. These inactivation rates are short enough to ensure that the bioburden of the surfaces and volumes would be negligible after prolonged exposure to hydrazine vapor. Thus, all the propellant tubing and internal tank surfaces exposed to hydrazine vapor do not contribute to the total spore count.

  16. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Donn McGuire; Steve Runyon; Richard Sigal; Bill Liddell; Thomas Williams; George Moridis

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. Hot Ice No. 1 was planned to test the Ugnu and West Sak sequences for gas hydrates and a concomitant free gas accumulation on Anadarko's 100% working interest acreage in section 30 of Township 9N, Range 8E of the Harrison Bay quadrangle of the North Slope of Alaska. The Ugnu and West Sak intervals are favorably positioned in the hydrate-stability zone over an area extending from Anadarko's acreage westward to the vicinity of the aforementioned gas-hydrate occurrences. This suggests that a large, north-to-south trending gas-hydrate accumulation may exist in that area. The presence of gas shows in the Ugnu and West Sak reservoirs in wells situated eastward and down dip of the Hot Ice location indicate that a free-gas accumulation may be trapped by gas hydrates. The Hot Ice No. 1 well was designed to core from the surface to the base of the West Sak interval using the

  17. Low-Energy Electron-Induced Transformations in Organolead Halide Perovskite.

    Science.gov (United States)

    Milosavljević, Aleksandar R; Huang, Weixin; Sadhu, Subha; Ptasinska, Sylwia

    2016-08-16

    Methylammonium lead iodide perovskite (MAPbI3 ), a prototype material for potentially high-efficient and low-cost organic-inorganic hybrid perovskite solar cells, has been investigated intensively in recent years. A study of low-energy electron-induced transformations in MAPbI3 is presented, performed by combining controlled electron-impact irradiation with X-ray photoelectron spectroscopy and scanning electron microscopy. Changes were observed in both the elemental composition and the morphology of irradiated MAPbI3 thin films as a function of the electron fluence for incident energies from 4.5 to 60 eV. The results show that low-energy electrons can affect structural and chemical properties of MAPbI3 . It is proposed that the transformations are triggered by the interactions with the organic part of the material (methylammonium), resulting in the MAPbI3 decomposition and aggregation of the hydrocarbon layer.

  18. Polypropylene/natural rubber thermoplastic vulcanizates by eco-friendly and sustainable electron induced reactive processing

    Science.gov (United States)

    Mondal, Manas; Gohs, Uwe; Wagenknecht, Udo; Heinrich, Gert

    2013-07-01

    TPVs are a special class of thermoplastic and elastomer blend where cross-linking of elastomeric phase takes place during melt mixing process known as dynamic vulcanization (DV). A 50/50 blend of natural rubber (NR) and polypropylene (PP) were dynamically vulcanized using Electron Induced Reactive Processing (EIReP) as a function of absorbed dose (150, 250, and 350 kGy) at fixed electron energy (1.5 MeV) and dose per rotation. Different methods like tensile test, DSC, melt rheology, and SEM have been employed to understand the structure-property relationship of the prepared samples. The results suggest that EIReP is a novel technique to offer handful of additional features without compromising the end user property.

  19. Compound Natural Gas Hydrate: A Natural System for Separation of Hydrate-Forming Gases

    Science.gov (United States)

    Max, M. D.; Osegovic, J. P.

    2007-12-01

    Natural processes that separate materials from a mixture may exert a major influence on the development of the atmospheres and surfaces of planets, moons, and other planetary bodies. Natural distillation and gravity separation, amongst others, are well known means of differentiating materials through liquid-gas partitioning. One of the least known attributes of clathrate (gas) hydrates is their potential effect on the evolution of planetary system oceans and atmospheres. Gas hydrates separate gases from mixtures of gases by concentrating preferred hydrate-forming materials (HFM) guests within the water-molecule cage structure of crystalline hydrate. Different HFMs have very different fields of stability. When multiple hydrate formers are present, a preference series based on their selective uptake exists. Compound hydrate, which is formed from two or more species of HFM, extract preferred HFM from a mixture in very different proportions to their relative percentages of the original mixture. These compound hydrates can have different formation and dissociation conditions depending on the evolution of the environment. That is, the phase boundary of the compound hydrate that is required for dissociation lies along a lower pressure - higher temperature course. Compound hydrates respond to variations in temperature, pressure, and HFM composition. On Earth, the primary naturally occurring hydrate of interest to global climate modeling is methane hydrate. Oceanic hydrate on Earth is the largest store of carbon in the biosphere that is immediately reactive to environmental change, and is capable of releasing large amounts of methane into the atmosphere over a short geological time span. Hydrate formation is essentially metastable and is very sensitive to environmental change and to gas flux. Where natural variations in temperature and pressure varies so that hydrate will form and dissociate in some cyclical manner, such as in oceans where sea level is capable of rising and

  20. Overview on Hydrate Coring, Handling and Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Jon Burger; Deepak Gupta; Patrick Jacobs; John Shillinglaw

    2003-06-30

    Gas hydrates are crystalline, ice-like compounds of gas and water molecules that are formed under certain thermodynamic conditions. Hydrate deposits occur naturally within ocean sediments just below the sea floor at temperatures and pressures existing below about 500 meters water depth. Gas hydrate is also stable in conjunction with the permafrost in the Arctic. Most marine gas hydrate is formed of microbially generated gas. It binds huge amounts of methane into the sediments. Worldwide, gas hydrate is estimated to hold about 1016 kg of organic carbon in the form of methane (Kvenvolden et al., 1993). Gas hydrate is one of the fossil fuel resources that is yet untapped, but may play a major role in meeting the energy challenge of this century. In June 2002, Westport Technology Center was requested by the Department of Energy (DOE) to prepare a ''Best Practices Manual on Gas Hydrate Coring, Handling and Analysis'' under Award No. DE-FC26-02NT41327. The scope of the task was specifically targeted for coring sediments with hydrates in Alaska, the Gulf of Mexico (GOM) and from the present Ocean Drilling Program (ODP) drillship. The specific subjects under this scope were defined in 3 stages as follows: Stage 1: Collect information on coring sediments with hydrates, core handling, core preservation, sample transportation, analysis of the core, and long term preservation. Stage 2: Provide copies of the first draft to a list of experts and stakeholders designated by DOE. Stage 3: Produce a second draft of the manual with benefit of input from external review for delivery. The manual provides an overview of existing information available in the published literature and reports on coring, analysis, preservation and transport of gas hydrates for laboratory analysis as of June 2003. The manual was delivered as draft version 3 to the DOE Project Manager for distribution in July 2003. This Final Report is provided for records purposes.

  1. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    2005-03-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Oil-field engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in Arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrates agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to help identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. As part of the project work scope, team members drilled and cored the HOT ICE No. 1 on Anadarko leases beginning in January 2003 and completed in March 2004. Due to scheduling constraints imposed by the Arctic drilling season, operations at the site were suspended between April 21, 2003 and January 30, 2004. An on-site core analysis laboratory was designed, constructed and used for determining physical characteristics of frozen core immediately after it was retrieved from the well. The well was drilled from a new and innovative Anadarko Arctic Platform that has a greatly reduced footprint and environmental impact. Final efforts of the project were to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists for future hydrate operations. Unfortunately, no gas hydrates were encountered in this well; however, a wealth of information was generated

  2. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Buddy King

    2004-07-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope drilled and cored a well The HOT ICE No.1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report.

  3. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Buddy King

    2004-06-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope drilled and cored a well The HOT ICE No.1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report.

  4. Experimental Study of Natural Gas Storage in Hydrates

    Institute of Scientific and Technical Information of China (English)

    孙志高; 王如竹; 郭开华; 樊栓狮

    2004-01-01

    Hydrate formation rate plays an important role in the making of hydrates for natural gas storage. The effect of sodium dodecyl sulfate (SDS), alkyl polysaccharide glycoside (APG) and cyclopentane (CP) on natural gas hydrate formation rate, induction time and storage capacity was studied. Micellar surfactant solutions were found to increase hydrate formation rate in a quiescent system and improve hydrate formation rate and natural gas storage capacity. The process of hydrate formation includes two stages with surfactant presence. Hydrate forms quickly in the first stage, and then the formation rate is slowed down. Surfactants (SDS or APG) reduce the induction time of hydrate formation. The effect of an anionic surfactant (SDS) on gas storage in hydrates is more pronounced compared to a nonionic surfactant (APG). CP also reduces the induction time of hydrate formation, but can not improve the natural gas storage capacity in hydrates.

  5. Methane Recovery from Hydrate-bearing Sediments

    Energy Technology Data Exchange (ETDEWEB)

    J. Carlos Santamarina; Costas Tsouris

    2011-04-30

    Gas hydrates are crystalline compounds made of gas and water molecules. Methane hydrates are found in marine sediments and permafrost regions; extensive amounts of methane are trapped in the form of hydrates. Methane hydrate can be an energy resource, contribute to global warming, or cause seafloor instability. This study placed emphasis on gas recovery from hydrate bearing sediments and related phenomena. The unique behavior of hydrate-bearing sediments required the development of special research tools, including new numerical algorithms (tube- and pore-network models) and experimental devices (high pressure chambers and micromodels). Therefore, the research methodology combined experimental studies, particle-scale numerical simulations, and macro-scale analyses of coupled processes. Research conducted as part of this project started with hydrate formation in sediment pores and extended to production methods and emergent phenomena. In particular, the scope of the work addressed: (1) hydrate formation and growth in pores, the assessment of formation rate, tensile/adhesive strength and their impact on sediment-scale properties, including volume change during hydrate formation and dissociation; (2) the effect of physical properties such as gas solubility, salinity, pore size, and mixed gas conditions on hydrate formation and dissociation, and it implications such as oscillatory transient hydrate formation, dissolution within the hydrate stability field, initial hydrate lens formation, and phase boundary changes in real field situations; (3) fluid conductivity in relation to pore size distribution and spatial correlation and the emergence of phenomena such as flow focusing; (4) mixed fluid flow, with special emphasis on differences between invading gas and nucleating gas, implications on relative gas conductivity for reservoir simulations, and gas recovery efficiency; (5) identification of advantages and limitations in different gas production strategies with

  6. Gas Hydrate Storage of Natural Gas

    Energy Technology Data Exchange (ETDEWEB)

    Rudy Rogers; John Etheridge

    2006-03-31

    Environmental and economic benefits could accrue from a safe, above-ground, natural-gas storage process allowing electric power plants to utilize natural gas for peak load demands; numerous other applications of a gas storage process exist. A laboratory study conducted in 1999 to determine the feasibility of a gas-hydrates storage process looked promising. The subsequent scale-up of the process was designed to preserve important features of the laboratory apparatus: (1) symmetry of hydrate accumulation, (2) favorable surface area to volume ratio, (3) heat exchanger surfaces serving as hydrate adsorption surfaces, (4) refrigeration system to remove heat liberated from bulk hydrate formation, (5) rapid hydrate formation in a non-stirred system, (6) hydrate self-packing, and (7) heat-exchanger/adsorption plates serving dual purposes to add or extract energy for hydrate formation or decomposition. The hydrate formation/storage/decomposition Proof-of-Concept (POC) pressure vessel and supporting equipment were designed, constructed, and tested. This final report details the design of the scaled POC gas-hydrate storage process, some comments on its fabrication and installation, checkout of the equipment, procedures for conducting the experimental tests, and the test results. The design, construction, and installation of the equipment were on budget target, as was the tests that were subsequently conducted. The budget proposed was met. The primary goal of storing 5000-scf of natural gas in the gas hydrates was exceeded in the final test, as 5289-scf of gas storage was achieved in 54.33 hours. After this 54.33-hour period, as pressure in the formation vessel declined, additional gas went into the hydrates until equilibrium pressure/temperature was reached, so that ultimately more than the 5289-scf storage was achieved. The time required to store the 5000-scf (48.1 hours of operating time) was longer than designed. The lower gas hydrate formation rate is attributed to a

  7. On the problem of electron-induced anisotropy effect in As{sub 2}S{sub 3}-based glasses

    Energy Technology Data Exchange (ETDEWEB)

    Balitska, V.O.; Shpotyuk, O.I. E-mail: karat@ipm.lviv.ua

    2000-05-02

    Effect of electron-induced anisotropy was observed in glassy As{sub 2}S{sub 3}-based samples irradiated by accelerated electrons (E=2.8 MeV) in the perpendicular plane to the probe light. Spectral and compositional dependences of this effect and its time stability at room temperature were discussed. It was supposed that the microstructural mechanism of the anisotropy effect was connected with electron-induced formation of new oriented (relatively to the electron flow) defects in the form of broken chemical bonds.

  8. Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation

    Science.gov (United States)

    Hunt, Andrew G.; Stern, Laura; Pohlman, John W.; Ruppel, Carolyn; Moscati, Richard J.; Landis, Gary P.

    2013-01-01

    As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sediments (some newly thawed), coal beds, and other sources. Carbon and deuterium stable isotopic fractionation during methane formation provides a first-order constraint on the processes (microbial or thermogenic) of methane generation. However, because gas hydrate formation and dissociation do not cause significant isotopic fractionation, a stable isotope-based hydrate-source determination is not possible. Here, we investigate patterns of mass-dependent noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

  9. Hydration Properties of Ground Granulated Blast-Furnace Slag (GGBS Under Different Hydration Environments

    Directory of Open Access Journals (Sweden)

    Shuhua LIU

    2017-02-01

    Full Text Available The hydration properties of various cementitious materials containing Ground Granulated Blast-furnace Slag (GGBS, two alkali-activated slag cements (AAS-1 and AAS-2 in which sodium silicate and sodium hydroxide act as alkaline activators respectively, supersulfated cement (SSC and slag Portland cement(PSC, are compared with ordinary Portland cement (OPC to investigate the effect of activating environment on the hydration properties in this study by determining the compressive strength of the pastes, the hydration heat of binders within 96 hours, and the hydration products at age of 28 days. The results show that C-S-H gels are the main hydrated products for all cementitious systems containing GGBS. Ca(OH2 is the hydration products of OPC and PSC paste. However, ettringite and gypsum crystals instead of Ca(OH2 are detected in SSC paste. Additionally, tobermorite, a crystalline C-S-H, and calcite are hydrated products in AAS-1. Tobermorite, cowlesite and calcite are hydrated products of AAS-2 as well. Based on strength results, AAS-1 paste exhibits the highest compressive strength followed by POC, PSC, SSC in order at all testing ages and AAS-2 give the lowest compressive strength except for the early age at 3 days, which is higher than SSC but still lower than PSC. From hydration heat analysis, alkalinity in the reaction solution is a vital factor influencing the initial hydration rate and the initial hydration rate from higher to lower is AAS-2, AAS-1, OPC, PSC and SSC. Although AAS possesses a faster reaction rate in the initial hours, cumulative hydration heat of AAS is comparably lower than that of OPC, but higher than those of PSC and SSC in turn, which indicates that the hydration heat of clinkers is much higher than that of slag.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.14934

  10. Detection and Production of Methane Hydrate

    Energy Technology Data Exchange (ETDEWEB)

    George Hirasaki; Walter Chapman; Gerald Dickens; Colin Zelt; Brandon Dugan; Kishore Mohanty; Priyank Jaiswal

    2011-12-31

    This project seeks to understand regional differences in gas hydrate systems from the perspective of as an energy resource, geohazard, and long-term climate influence. Specifically, the effort will: (1) collect data and conceptual models that targets causes of gas hydrate variance, (2) construct numerical models that explain and predict regional-scale gas hydrate differences in 2-dimensions with minimal 'free parameters', (3) simulate hydrocarbon production from various gas hydrate systems to establish promising resource characteristics, (4) perturb different gas hydrate systems to assess potential impacts of hot fluids on seafloor stability and well stability, and (5) develop geophysical approaches that enable remote quantification of gas hydrate heterogeneities so that they can be characterized with minimal costly drilling. Our integrated program takes advantage of the fact that we have a close working team comprised of experts in distinct disciplines. The expected outcomes of this project are improved exploration and production technology for production of natural gas from methane hydrates and improved safety through understanding of seafloor and well bore stability in the presence of hydrates. The scope of this project was to more fully characterize, understand, and appreciate fundamental differences in the amount and distribution of gas hydrate and how this would affect the production potential of a hydrate accumulation in the marine environment. The effort combines existing information from locations in the ocean that are dominated by low permeability sediments with small amounts of high permeability sediments, one permafrost location where extensive hydrates exist in reservoir quality rocks and other locations deemed by mutual agreement of DOE and Rice to be appropriate. The initial ocean locations were Blake Ridge, Hydrate Ridge, Peru Margin and GOM. The permafrost location was Mallik. Although the ultimate goal of the project was to understand

  11. Prospecting for marine gas hydrate resources

    Science.gov (United States)

    Boswell, Ray; Shipp, Craig; Reichel, Thomas; Shelander, Dianna; Saeki, Tetsuo; Frye, Matthew; Shedd, William; Collett, Timothy S.; McConnell, Daniel R.

    2016-01-01

    As gas hydrate energy assessment matures worldwide, emphasis has evolved away from confirmation of the mere presence of gas hydrate to the more complex issue of prospecting for those specific accumulations that are viable resource targets. Gas hydrate exploration now integrates the unique pressure and temperature preconditions for gas hydrate occurrence with those concepts and practices that are the basis for conventional oil and gas exploration. We have aimed to assimilate the lessons learned to date in global gas hydrate exploration to outline a generalized prospecting approach as follows: (1) use existing well and geophysical data to delineate the gas hydrate stability zone (GHSZ), (2) identify and evaluate potential direct indications of hydrate occurrence through evaluation of interval of elevated acoustic velocity and/or seismic events of prospective amplitude and polarity, (3) mitigate geologic risk via regional seismic and stratigraphic facies analysis as well as seismic mapping of amplitude distribution along prospective horizons, and (4) mitigate further prospect risk through assessment of the evidence of gas presence and migration into the GHSZ. Although a wide range of occurrence types might ultimately become viable energy supply options, this approach, which has been tested in only a small number of locations worldwide, has directed prospect evaluation toward those sand-hosted, high-saturation occurrences that were presently considered to have the greatest future commercial potential.

  12. Gas Hydrates Research Programs: An International Review

    Energy Technology Data Exchange (ETDEWEB)

    Jorge Gabitto; Maria Barrufet

    2009-12-09

    Gas hydrates sediments have the potential of providing a huge amount of natural gas for human use. Hydrate sediments have been found in many different regions where the required temperature and pressure conditions have been satisfied. Resource exploitation is related to the safe dissociation of the gas hydrate sediments. Basic depressurization techniques and thermal stimulation processes have been tried in pilot efforts to exploit the resource. There is a growing interest in gas hydrates all over the world due to the inevitable decline of oil and gas reserves. Many different countries are interested in this valuable resource. Unsurprisingly, developed countries with limited energy resources have taken the lead in worldwide gas hydrates research and exploration. The goal of this research project is to collect information in order to record and evaluate the relative strengths and goals of the different gas hydrates programs throughout the world. A thorough literature search about gas hydrates research activities has been conducted. The main participants in the research effort have been identified and summaries of their past and present activities reported. An evaluation section discussing present and future research activities has also been included.

  13. Gas hydrate dissociation structures in submarine slopes

    Energy Technology Data Exchange (ETDEWEB)

    Gidley, I.; Grozic, J.L.H. [Calgary Univ., AB (Canada). Dept. of Civil Engineering

    2008-07-01

    Studies have suggested that gas hydrates may play a role in submarine slope failures. However, the mechanics surrounding such failures are poorly understood. This paper discussed experimental tests conducted on a small-scale physical model of submarine soils with hydrate inclusions. The laboratory tests investigated the effects of slope angle and depth of burial of the hydrate on gas escape structures and slope stability. Laponite was used to model the soils due to its ability to swell and produce a clear, colorless thixotropic gel when dispersed in water. An R-11 refrigerant was used to form hydrate layers and nodules. The aim of the experiment was to investigate the path of the fluid escape structures and the development of a subsequent slip plane caused by the dissociation of the R-11 hydrates. Slope angles of 5, 10, and 15 degrees were examined. Slopes were examined using high-resolution, high-speed imaging techniques. Hydrate placement and slope inclinations were varied in order to obtain stability data. Results of the study showed that slope angle influenced the direction of travel of the escaping gas, and that the depth of burial affected sensitivity to slope angle. Theoretical models developed from the experimental data have accurately mapped deformations and stress states during testing. Further research is being conducted to investigate the influence of the size, shape, and placement of the hydrates. 30 refs., 15 figs.

  14. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Buddy King

    2004-03-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the second year of a three-year endeavor being sponsored by Maurer Technology, Noble, and Anadarko Petroleum, in partnership with the DOE. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition. We plan to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. We also plan to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope is to drill and core a well on Anadarko leases in FY 2003 and 2004. We are also using an on-site core analysis laboratory to determine some of the physical characteristics of the hydrates and surrounding rock. The well is being drilled from a new Anadarko Arctic Platform that will have minimal footprint and environmental impact. We hope to correlate geology, geophysics, logs, and drilling and production data to allow reservoir models to be calibrated. Ultimately, our goal is to form an objective technical and economic evaluation of reservoir potential in Alaska.

  15. Methane hydrate stability and anthropogenic climate change

    Directory of Open Access Journals (Sweden)

    D. Archer

    2007-07-01

    Full Text Available Methane frozen into hydrate makes up a large reservoir of potentially volatile carbon below the sea floor and associated with permafrost soils. This reservoir intuitively seems precarious, because hydrate ice floats in water, and melts at Earth surface conditions. The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth's radiation budget equivalent to a factor of 10 increase in atmospheric CO2.

    Hydrates are releasing methane to the atmosphere today in response to anthropogenic warming, for example along the Arctic coastline of Siberia. However most of the hydrates are located at depths in soils and ocean sediments where anthropogenic warming and any possible methane release will take place over time scales of millennia. Individual catastrophic releases like landslides and pockmark explosions are too small to reach a sizable fraction of the hydrates. The carbon isotopic excursion at the end of the Paleocene has been interpreted as the release of thousands of Gton C, possibly from hydrates, but the time scale of the release appears to have been thousands of years, chronic rather than catastrophic.

    The potential climate impact in the coming century from hydrate methane release is speculative but could be comparable to climate feedbacks from the terrestrial biosphere and from peat, significant but not catastrophic. On geologic timescales, it is conceivable that hydrates could release as much carbon to the atmosphere/ocean system as we do by fossil fuel combustion.

  16. Methane hydrate stability and anthropogenic climate change

    Directory of Open Access Journals (Sweden)

    D. Archer

    2007-04-01

    Full Text Available Methane frozen into hydrate makes up a large reservoir of potentially volatile carbon below the sea floor and associated with permafrost soils. This reservoir intuitively seems precarious, because hydrate ice floats in water, and melts at Earth surface conditions. The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth's radiation budget equivalent to a factor of 10 increase in atmospheric CO2.

    Hydrates are releasing methane to the atmosphere today in response to anthropogenic warming, for example along the Arctic coastline of Siberia. However most of the hydrates are located at depths in soils and ocean sediments where anthropogenic warming and any possible methane release will take place over time scales of millennia. Individual catastrophic releases like landslides and pockmark explosions are too small to reach a sizable fraction of the hydrates. The carbon isotopic excursion at the end of the Paleocene has been interpreted as the release of thousands of Gton C, possibly from hydrates, but the time scale of the release appears to have been thousands of years, chronic rather than catastrophic.

    The potential climate impact in the coming century from hydrate methane release is speculative but could be comparable to climate feedbacks from the terrestrial biosphere and from peat, significant but not catastrophic. On geologic timescales, it is conceivable that hydrates could release much carbon to the atmosphere/ocean system as we do by fossil fuel combustion.

  17. Proton percolation on hydrated lysozyme powders

    OpenAIRE

    Careri, G; Giansanti, A; Rupley, John A.

    1986-01-01

    The framework of percolation theory is used to analyze the hydration dependence of the capacitance measured for protein samples of pH 3-10, at frequencies from 10 kHz to 4 MHz. For all samples there is a critical value of the hydration at which the capacitance sharply increases with increase in hydration level. The threshold hc = 0.15 g of water per g of protein is independent of pH below pH 9 and shows no solvent deuterium isotope effect. The fractional coverage of the surface at hc is in cl...

  18. Glass powder blended cement hydration modelling

    Science.gov (United States)

    Saeed, Huda

    The use of waste materials in construction is among the most attractive options to consume these materials without affecting the environment. Glass is among these types of potential waste materials. In this research, waste glass in powder form, i.e. glass powder (GP) is examined for potential use in enhancing the characteristics of concrete on the basis that it is a pozzolanic material. The experimental and the theoretical components of the work are carried out primarily to prove that glass powder belongs to the "family" of the pozzolanic materials. The chemical and physical properties of the hydrated activated glass powder and the hydrated glass powder cement on the microstructure level have been studied experimentally and theoretically. The work presented in this thesis consists of two main phases. The first phase contains experimental investigations of the reaction of glass powder with calcium hydroxide (CH) and water. In addition, it includes experiments that are aimed at determining the consumption of water and CH with time. The reactivity, degree of hydration, and nature of the pore solution of the glass powder-blended cement pastes and the effect of adding different ratios of glass powder on cement hydration is also investigated. The experiments proved that glass powder has a pozzolanic effect on cement hydration; hence it enhances the chemical and physical properties of cement paste. Based on the experimental test results, it is recommended to use a glass powder-to-cement ratio (GP/C) of 10% as an optimum ratio to achieve the best hydration and best properties of the paste. Two different chemical formulas for the produced GP C-S-H gel due to the pure GP and GP-CH pozzolanic reaction hydration are proposed. For the pure GP hydration, the produced GP C-S-H gel has a calcium-to-silica ratio (C/S) of 0.164, water-to-silica ratio (H/S) of 1.3 and sodium/silica ratio (N/S) of 0.18. However, for the GP-CH hydration, the produced GP C-S-H gel has a C/S ratio of 1

  19. Effect of Some Admixtures on the Hydration of Silica Fume and Hydrated Lime

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effects of sodium salt of naphthalene formaldehyde sulfonic acid and stearic acid on the hydration of silica fume and Ca(0H)2 have been investigated. The hydration was carried out at 60℃ and W/S ratio of 4 for various time intervals namely, 1, 3, 7 and 28 days and in the presence of 0.2% and 5% superplasticizer and stearic acid. The results of the hydration kinetics show that both admixtures accelerate the hydration reaction of silica fume and calcium hydroxide during the first 7 days. Whereas, after 28 days hydration there is no significant effect. Generally, most of free calcium hydroxide seems to be consumed after 28 days. In addition, the phase composition as well as the microstructure of the formed hydrates was examined by using X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) respectively.

  20. X-chromosome inactivation and escape

    Indian Academy of Sciences (India)

    Christine M. Disteche; Joel B. Berletch

    2015-12-01

    X-chromosome inactivation, which was discovered by Mary Lyon in 1961 results in random silencing of one X chromosome in female mammals. This review is dedicated to Mary Lyon, who passed away last year. She predicted many of the features of X inactivation, for e.g., the existence of an X inactivation center, the role of L1 elements in spreading of silencing and the existence of genes that escape X inactivation. Starting from her published work here we summarize advances in the field.

  1. Three-dimensional distribution of gas hydrate beneath southern Hydrate Ridge: Constraints from ODP Leg 204

    Science.gov (United States)

    Trehu, A.M.; Long, P.E.; Torres, M.E.; Bohrmann, G.; Rack, F.R.; Collett, T.S.; Goldberg, D.S.; Milkov, A.V.; Riedel, M.; Schultheiss, P.; Bangs, N.L.; Barr, S.R.; Borowski, W.S.; Claypool, G.E.; Delwiche, M.E.; Dickens, G.R.; Gracia, E.; Guerin, G.; Holland, M.; Johnson, J.E.; Lee, Y.-J.; Liu, C.-S.; Su, X.; Teichert, B.; Tomaru, H.; Vanneste, M.; Watanabe, M. E.; Weinberger, J.L.

    2004-01-01

    Large uncertainties about the energy resource potential and role in global climate change of gas hydrates result from uncertainty about how much hydrate is contained in marine sediments. During Leg 204 of the Ocean Drilling Program (ODP) to the accretionary complex of the Cascadia subduction zone, we sampled the gas hydrate stability zone (GHSZ) from the seafloor to its base in contrasting geological settings defined by a 3D seismic survey. By integrating results from different methods, including several new techniques developed for Leg 204, we overcome the problem of spatial under-sampling inherent in robust methods traditionally used for estimating the hydrate content of cores and obtain a high-resolution, quantitative estimate of the total amount and spatial variability of gas hydrate in this structural system. We conclude that high gas hydrate content (30-40% of pore space or 20-26% of total volume) is restricted to the upper tens of meters below the seafloor near the summit of the structure, where vigorous fluid venting occurs. Elsewhere, the average gas hydrate content of the sediments in the gas hydrate stability zone is generally <2% of the pore space, although this estimate may increase by a factor of 2 when patchy zones of locally higher gas hydrate content are included in the calculation. These patchy zones are structurally and stratigraphically controlled, contain up to 20% hydrate in the pore space when averaged over zones ???10 m thick, and may occur in up to ???20% of the region imaged by 3D seismic data. This heterogeneous gas hydrate distribution is an important constraint on models of gas hydrate formation in marine sediments and the response of the sediments to tectonic and environmental change. ?? 2004 Published by Elsevier B.V.

  2. Experimental Investigation of Effect on Hydrate Formation in Spray Reactor

    Directory of Open Access Journals (Sweden)

    Jianzhong Zhao

    2015-01-01

    Full Text Available The effects of reaction condition on hydrate formation were conducted in spray reactor. The temperature, pressure, and gas volume of reaction on hydrate formation were measured in pure water and SDS solutions at different temperature and pressure with a high-pressure experimental rig for hydrate formation. The experimental data and result reveal that additives could improve the hydrate formation rate and gas storage capacity. Temperature and pressure can restrict the hydrate formation. Lower temperature and higher pressure can promote hydrate formation, but they can increase production cost. So these factors should be considered synthetically. The investigation will promote the advance of gas storage technology in hydrates.

  3. A Hydrate Database: Vital to the Technical Community

    Directory of Open Access Journals (Sweden)

    D Sloan

    2007-06-01

    Full Text Available Natural gas hydrates may contain more energy than all the combined other fossil fuels, causing hydrates to be a potentially vital aspect of both energy and climate change. This article is an overview of the motivation, history, and future of hydrate data management using a CODATA vehicle to connect international hydrate databases. The basis is an introduction to the Gas Hydrate Markup Language (GHML to connect various hydrate databases. The accompanying four articles on laboratory hydrate data by Smith et al., on field hydrate data by L?wner et al., on hydrate modeling by Wang et al., and on construction of a Chinese gas hydrate system by Xiao et al. provide details of GHML in their respective areas.

  4. Vibrational dynamics of hydration water in amylose

    CERN Document Server

    Cavatorta, F; Albanese, G; Angelini, N

    2002-01-01

    We present a study of the dynamical properties of hydration water associated with amylose helices, based on low-temperature vibrational spectra collected using the TOSCA inelastic spectrometer at ISIS. The structural constraints of the polysaccharidic chains favour the formation of a high-density structure for water, which has been suggested by Imberty and Perez on the basis of conformational analysis. According to this model, hydration water can only enter the pores formed by six adjacent helices and completely fills the pores at a hydration level of about 0.27-g water/g dry amylose. Our measurements show that the dynamical behaviour of hydration water is similar to that observed in high-density amorphous ice. (orig.)

  5. ConocoPhillips Gas Hydrate Production Test

    Energy Technology Data Exchange (ETDEWEB)

    Schoderbek, David; Farrell, Helen; Howard, James; Raterman, Kevin; Silpngarmlert, Suntichai; Martin, Kenneth; Smith, Bruce; Klein, Perry

    2013-06-30

    Work began on the ConocoPhillips Gas Hydrates Production Test (DOE award number DE-NT0006553) on October 1, 2008. This final report summarizes the entire project from January 1, 2011 to June 30, 2013.

  6. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Donn McGuire; Thomas Williams; Bjorn Paulsson; Alexander Goertz

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a drilling hazard by the oil and gas industry for years. Drilling engineers working in Russia, Canada and the USA have documented numerous problems, including drilling kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrates as a potential energy source agree that the resource potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained from physical samples taken from actual hydrate-bearing rocks. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The project team drilled and continuously cored the Hot Ice No. 1 well on Anadarko-leased acreage beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and used for determining physical characteristics of hydrates and surrounding rock. After the well was logged, a 3D vertical seismic profile (VSP) was recorded to calibrate the shallow geologic section with seismic data and to investigate techniques to better resolve lateral subsurface variations of potential hydrate-bearing strata. Paulsson Geophysical Services, Inc. deployed their 80 level 3C clamped borehole seismic receiver array in the wellbore to record samples every 25 ft. Seismic vibrators were successively positioned at 1185 different surface positions in a circular pattern around the wellbore. This technique generated a 3D image of the subsurface. Correlations were

  7. Hydration states of AFm cement phases

    Energy Technology Data Exchange (ETDEWEB)

    Baquerizo, Luis G., E-mail: luis.baquerizoibarra@holcim.com [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Matschei, Thomas [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Scrivener, Karen L. [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Saeidpour, Mahsa; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)

    2015-07-15

    The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered double hydrate (LDH) family having positively charged layers and water plus charge-balancing anions in the interlayer. It is known that these phases present different hydration states (i.e. varying water content) depending on the relative humidity (RH), temperature and anion type, which might be linked to volume changes (swelling and shrinkage). Unfortunately the stability conditions of these phases are insufficiently reported. This paper presents novel experimental results on the different hydration states of the most important AFm phases: monocarboaluminate, hemicarboaluminate, strätlingite, hydroxy-AFm and monosulfoaluminate, and the thermodynamic properties associated with changes in their water content during absorption/desorption. This data opens the possibility to model the response of cementitious systems during drying and wetting and to engineer systems more resistant to harsh external conditions.

  8. Polyethylene oxide hydration in grafted layers

    Science.gov (United States)

    Dormidontova, Elena; Wang, Zilu

    Hydration of water soluble polymers is one of the key-factors defining their conformation and properties, similar to biopolymers. Polyethylene oxide (PEO) is one of the most important biomedical-applications polymers and is known for its reverse temperature solubility due to hydrogen bonding with water. As in many practical applications PEO chains are grafted to surfaces, e.g. of nanoparticles or planar surfaces, it is important to understand PEO hydration in such grafted layers. Using atomistic molecular dynamic simulations we investigate the details of molecular conformation and hydration of PEO end-grafted to gold surfaces. We analyze polymer and water density distribution as a function of distance from the surface for different grafting densities. Based on a detailed analysis of hydrogen bonding between polymer and water in grafted PEO layers, we will discuss the extent of PEO hydration and its implication for polymer conformation, mobility and layer properties. This research is supported by NSF (DMR-1410928).

  9. Formulating formation mechanism of natural gas hydrates.

    Science.gov (United States)

    Palodkar, Avinash V; Jana, Amiya K

    2017-07-25

    A large amount of energy, perhaps twice the total amount of all other hydrocarbon reserves combined, is trapped within gas hydrate deposits. Despite emerging as a potential energy source for the world over the next several hundred years and one of the key factors in causing future climate change, gas hydrate is poorly known in terms of its formation mechanism. To address this issue, a mathematical formulation is proposed in the form of a model to represent the physical insight into the process of hydrate growth that occurs on the surface and in the irregular nanometer-sized pores of the distributed porous particles. To evaluate the versatility of this rigorous model, the experimental data is used for methane (CH4) and carbon dioxide (CO2) hydrates grown in different porous media with a wide range of considerations.

  10. Hydrate Control for Gas Storage Operations

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Savidge

    2008-10-31

    The overall objective of this project was to identify low cost hydrate control options to help mitigate and solve hydrate problems that occur in moderate and high pressure natural gas storage field operations. The study includes data on a number of flow configurations, fluids and control options that are common in natural gas storage field flow lines. The final phase of this work brings together data and experience from the hydrate flow test facility and multiple field and operator sources. It includes a compilation of basic information on operating conditions as well as candidate field separation options. Lastly the work is integrated with the work with the initial work to provide a comprehensive view of gas storage field hydrate control for field operations and storage field personnel.

  11. Quantifying hydrate formation and kinetic inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Sloan, E.D.; Subramanian, S.; Matthews, P.N.; Lederhos, J.P.; Khokhar, A.A. [Colorado School of Mines, Golden, CO (United States). Center for Hydrate Research

    1998-08-01

    In the Prausnitz tradition, molecular and macroscopic evidence of hydrate formation and kinetic inhibition is presented. On the microscopic level, the first Raman spectra are presented for the formation of both uninhibited and inhibited methane hydrates with time. This method has the potential to provide a microscopic-based kinetics model. Three macroscopic aspects of natural gas hydrate kinetic inhibition are also reported: (1) The effect of hydrate dissociation residual structures was measured, which has application in decreasing the time required for subsequent formation. (2) The performance of a kinetic inhibitor (poly(N-vinylcaprolactam) or PVCap) was measured and correlated as a function of PVCap molecular weight and concentrations of PVCap, methanol, and salt in the aqueous phase. (3) Long-duration test results indicated that the use of PVCap can prevent pipeline blockage for a time exceeding the aqueous phase residence time in some gas pipelines.

  12. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Ali Kadaster; Bill Liddell; Tommy Thompson; Thomas Williams; Michael Niedermayr

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project was a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope included drilling and coring a well (Hot Ice No. 1) on Anadarko leases beginning in FY 2003 and completed in 2004. During the first drilling season, operations were conducted at the site between January 28, 2003 to April 30, 2003. The well was spudded and drilled to a depth of 1403 ft. Due to the onset of warmer weather, work was then suspended for the season. Operations at the site were continued after the tundra was re-opened the following season. Between January 12, 2004 and March 19, 2004, the well was drilled and cored to a final depth of 2300 ft. An on-site core analysis laboratory was built and implemented for determining physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. Final efforts of the project are to correlate geology, geophysics, logs, and drilling and

  13. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    2004-11-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to help identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. As part of the project work scope, team members drilled and cored a well (the Hot Ice No. 1) on Anadarko leases beginning in January 2003 and completed in March 2004. Due to scheduling constraints imposed by the Arctic drilling season, operations at the site were suspended between April 21, 2003 and January 30, 2004. An on-site core analysis laboratory was constructed and used for determining physical characteristics of frozen core immediately after it was retrieved from the well. The well was drilled from a new and innovative Anadarko Arctic Platform that has a greatly reduced footprint and environmental impact. Final efforts of the project were to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists for future hydrate operations. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained

  14. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to help identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. As part of the project work scope, team members drilled and cored a well (the Hot Ice No. 1) on Anadarko leases beginning in January 2003 and completed in March 2004. Due to scheduling constraints imposed by the Arctic drilling season, operations at the site were suspended between April 21, 2003 and January 30, 2004. An on-site core analysis laboratory was constructed and used for determining physical characteristics of frozen core immediately after it was retrieved from the well. The well was drilled from a new and innovative Anadarko Arctic Platform that has a greatly reduced footprint and environmental impact. Final efforts of the project were to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists for future hydrate operations. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained

  15. Experimental Dissociation of Methane Hydrates Through Depressurization

    Science.gov (United States)

    Borgfeldt, T.; Flemings, P. B.; Meyer, D.; You, K.

    2015-12-01

    We dissociated methane hydrates by stepwise depressurization. The initial hydrates were formed by injecting gas into a cylindrical sample of brine-saturated, coarse-grained sand at hydrate-stable conditions with the intention of reaching three-phase equilibrium. The sample was initially at 1°C with a pore pressure of 1775 psi and a salinity of 7 wt. % NaBr. The depressurization setup consisted of one pump filled with tap water attached to the confining fluid port and a second pump attached to the inlet port where the methane was injected. Depressurization was conducted over sixteen hours at a constant temperature of 1°C. The pore pressure was stepwise reduced from 1775 psi to atmospheric pressure by pulling known volumes of gas from the sample. After each extraction, we recorded the instantaneous and equilibrium pore pressure. 0.503 moles of methane were removed from the sample. The pore pressure decreased smoothly and nonlinearly with the cumulative gas withdrawn from the sample. We interpret that hydrate began to dissociate immediately with depressurization, and it continued to dissociate when the pressure decreased below the three-phase pressure for 1°C and 0 wt. % salinity. Two breaks in slope in the pressure vs. mass extracted data are bounded by smooth, nonlinear curves with differing slopes on either side. We attribute the breaks to dissociation of three zones of hydrate concentration. We created a box model to simulate the experimental behavior. For a 10% initial gas saturation (estimated from the hydrate formation experiment and based on mass conservation), an initial hydrate saturation of 55% is required to match the total methane extracted from the sample. Future experiments will be conducted over a longer timespan while monitoring hydrate dissociation with CT imaging throughout the process.

  16. Hydration of polyethylene glycol-grafted liposomes.

    OpenAIRE

    Tirosh, O; Barenholz, Y.; Katzhendler, J; Priev, A

    1998-01-01

    This study aimed to characterize the effect of polyethylene glycol of 2000 molecular weight (PEG2000) attached to a dialkylphosphatidic acid (dihexadecylphosphatidyl (DHP)-PEG2000) on the hydration and thermodynamic stability of lipid assemblies. Differential scanning calorimetry, densitometry, and ultrasound velocity and absorption measurements were used for thermodynamic and hydrational characterization. Using a differential scanning calorimetry technique we showed that each molecule of PEG...

  17. Exploitation of subsea gas hydrate reservoirs

    Science.gov (United States)

    Janicki, Georg; Schlüter, Stefan; Hennig, Torsten; Deerberg, Görge

    2016-04-01

    Natural gas hydrates are considered to be a potential energy resource in the future. They occur in permafrost areas as well as in subsea sediments and are stable at high pressure and low temperature conditions. According to estimations the amount of carbon bonded in natural gas hydrates worldwide is two times larger than in all known conventional fossil fuels. Besides technical challenges that have to be overcome climate and safety issues have to be considered before a commercial exploitation of such unconventional reservoirs. The potential of producing natural gas from subsea gas hydrate deposits by various means (e.g. depressurization and/or injection of carbon dioxide) is numerically studied in the frame of the German research project »SUGAR«. The basic mechanisms of gas hydrate formation/dissociation and heat and mass transport in porous media are considered and implemented into a numerical model. The physics of the process leads to strong non-linear couplings between hydraulic fluid flow, hydrate dissociation and formation, hydraulic properties of the sediment, partial pressures and seawater solution of components and the thermal budget of the system described by the heat equation. This paper is intended to provide an overview of the recent development regarding the production of natural gas from subsea gas hydrate reservoirs. It aims at giving a broad insight into natural gas hydrates and covering relevant aspects of the exploitation process. It is focused on the thermodynamic principles and technological approaches for the exploitation. The effects occurring during natural gas production within hydrate filled sediment layers are identified and discussed by means of numerical simulation results. The behaviour of relevant process parameters such as pressure, temperature and phase saturations is described and compared for different strategies. The simulations are complemented by calculations for different safety relevant problems.

  18. Preservation of methane hydrate at 1 atm

    Science.gov (United States)

    Stern, L.A.; Circone, S.; Kirby, S.H.; Durham, W.B.

    2001-01-01

    A "pressure-release" method that enables reproducible bulk preservation of pure, porous, methane hydrate at conditions 50 to 75 K above its equilibrium T (193 K) at 1 atm is refined. The amount of hydrate preserved by this method appears to be greatly in excess of that reported in the previous citations, and is likely the result of a mechanism different from ice shielding.

  19. Electron-induced chemistry of methyl chloride caged within amorphous solid water

    Science.gov (United States)

    Horowitz, Yonatan; Asscher, Micha

    2013-10-01

    The interaction of low energy electrons (1.0-25 eV) with methyl-chloride (CD3Cl) molecules, caged within Amorphous Solid Water (ASW) films, 10-120 monolayer (ML) thick, has been studied on top of a Ru(0001) substrate under Ultra High Vacuum (UHV) conditions. While exposing the ASW film to 3 eV electrons a static electric field up to 8 × 108 V/m is developed inside the ASW film due to the accumulation of trapped electrons that produce a plate capacitor voltage of exactly 3 V. At the same time while the electrons continuously strike the ASW surface, they are transmitted through the ASW film at currents of ca. 3 × 10-7 A. These electrons transiently attach to the caged CD3Cl molecules leading to C-Cl bond scission via Dissociative Electron Attachment (DEA) process. The electron induced dissociation cross sections and product formation rate constants at 3.0 eV incident electrons at ASW film thicknesses of 10 ML and 40 ML were derived from model simulations supported by Thermal Programmed Desorption (TPD) experimental data. For 3.0 eV electrons the CD3Cl dissociation cross section is 3.5 × 10-16 cm2, regardless of ASW film thickness. TPD measurements reveal that the primary product is deuterated methane (D3CH) and the minor one is deuterated ethane (C2D6).

  20. Low energy electron induced reactions in fluorinated acetamide - probing negative ions and neutral stable counterparts*

    Science.gov (United States)

    Kopyra, Janina; König-Lehmann, Constanze; Illenberger, Eugen; Warneke, Jonas; Swiderek, Petra

    2016-06-01

    Electron impact to trifluoroacetamide (CF3CONH2, TFAA) in the energy range 0-12 eV leads to a variety of negative fragment ions which are formed via dissociative electron attachment (DEA). The underlying reactions range from single bond cleavages to remarkably complex reactions that lead to loss of the neutral units HF, H2O and HNCO as deduced from their directly observed ionic counterparts (M - H2O)-, (M - HF)- and (M - HNCO)-. Also formed are the pseudo-halogen ions CN- and OCN-. All these reactions proceed dominantly via a resonance located near 1 eV, i.e., electrons at subexcitation energies trigger reactions involving multiple bond cleavages. The electron induced generation of the neutral molecules HF, H2O and HNCO in condensed TFAA films is probed by temperature controlled thermal desorption spectrometry (TDS) which can be viewed as a complementary techniques to gas-phase experiments in DEA to directly probe the neutral counterparts. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  1. Bond selectivity in electron-induced reaction due to directed recoil on an anisotropic substrate

    Science.gov (United States)

    Anggara, Kelvin; Huang, Kai; Leung, Lydie; Chatterjee, Avisek; Cheng, Fang; Polanyi, John C.

    2016-12-01

    Bond-selective reaction is central to heterogeneous catalysis. In heterogeneous catalysis, selectivity is found to depend on the chemical nature and morphology of the substrate. Here, however, we show a high degree of bond selectivity dependent only on adsorbate bond alignment. The system studied is the electron-induced reaction of meta-diiodobenzene physisorbed on Cu(110). Of the adsorbate's C-I bonds, C-I aligned `Along' the copper row dissociates in 99.3% of the cases giving surface reaction, whereas C-I bond aligned `Across' the rows dissociates in only 0.7% of the cases. A two-electronic-state molecular dynamics model attributes reaction to an initial transition to a repulsive state of an Along C-I, followed by directed recoil of C towards a Cu atom of the same row, forming C-Cu. A similar impulse on an Across C-I gives directed C that, moving across rows, does not encounter a Cu atom and hence exhibits markedly less reaction.

  2. Surfactant effects on SF6 hydrate formation.

    Science.gov (United States)

    Lee, Bo Ram; Lee, Ju Dong; Lee, Hyun Ju; Ryu, Young Bok; Lee, Man Sig; Kim, Young Seok; Englezos, Peter; Kim, Myung Hyun; Kim, Yang Do

    2009-03-01

    Sulfur hexafluoride (SF(6)) has been widely used in a variety of industrial processes, but it is one of the most potent greenhouse gases. For this reason, it is necessary to separate or collect it from waste gas streams. One separation method is through hydrate crystal formation. In this study, SF(6) hydrate was formed in aqueous surfactant solutions of 0.00, 0.01, 0.05, 0.15 and 0.20 wt% to investigate the effects of surfactants on the hydrate formation rates. Three surfactants, Tween 20 (Tween), sodium dodecyl sulfate (SDS) and linear alkyl benzene sulfonate (LABS), were tested in a semi-batch stirred vessel at the constant temperature and pressures of 276.2 K and 0.78 MPa, respectively. All surfactants showed kinetic promoter behavior for SF(6) hydrate formation. It was also found that SF(6) hydrate formation proceeded in two stages with the second stage being the most rapid. In situ Raman spectroscopy analysis revealed that the increased gas consumption rate with the addition of surfactant was possibly due to the increased gas filling rate in the hydrate cavity.

  3. In Situ Raman Analyses of Natural Gas and Gas Hydrates at Hydrate Ridge, Oregon

    Science.gov (United States)

    Peltzer, E. T.; White, S. N.; Dunk, R. M.; Brewer, P. G.; Sherman, A. D.; Schmidt, K.; Hester, K. C.; Sloan, E. D.

    2004-12-01

    During a July 2004 cruise to Hydrate Ridge, Oregon, MBARI's sea-going laser Raman spectrometer was used to obtain in situ Raman spectra of natural gas hydrates and natural gas venting from the seafloor. This was the first in situ analysis of gas hydrates on the seafloor. The hydrate spectra were compared to laboratory analyses performed at the Center for Hydrate Research, Colorado School of Mines. The natural gas spectra were compared to MBARI gas chromatography (GC) analyses of gas samples collected at the same site. DORISS (Deep Ocean Raman In Situ Spectrometer) is a laboratory model laser Raman spectrometer from Kaiser Optical Systems, Inc modified at MBARI for deployment in the deep ocean. It has been successfully deployed to depths as great as 3600 m. Different sampling optics provide flexibility in adapting the instrument to a particular target of interest. An immersion optic was used to analyze natural gas venting from the seafloor at South Hydrate Ridge ( ˜780 m depth). An open-bottomed cube was placed over the vent to collect the gas. The immersion optic penetrated the side of the cube as did a small heater used to dissociate any hydrate formed during sample collection. To analyze solid hydrates at both South and North Hydrate Ridge ( ˜590 m depth), chunks of hydrate were excavated from the seafloor and collected in a glass cylinder with a mesh top. A stand-off optic was used to analyze the hydrate inside the cylinder. Due to the partial opacity of the hydrate and the small focal volume of the sampling optic, a precision underwater positioner (PUP) was used to focus the laser spot onto the hydrate. PUP is a stand-alone system with three degrees-of-freedom, capable of moving the DORISS probe head with a precision of 0.1 mm. In situ Raman analyses of the gas indicate that it is primarily methane. This is verified by GC analyses of samples collected from the same site. Other minor constituents (such as CO2 and higher hydrocarbons) are present but may be in

  4. Photodynamic inactivation of mammalian viruses and bacteriophages.

    Science.gov (United States)

    Costa, Liliana; Faustino, Maria Amparo F; Neves, Maria Graça P M S; Cunha, Angela; Almeida, Adelaide

    2012-07-01

    Photodynamic inactivation (PDI) has been used to inactivate microorganisms through the use of photosensitizers. The inactivation of mammalian viruses and bacteriophages by photosensitization has been applied with success since the first decades of the last century. Due to the fact that mammalian viruses are known to pose a threat to public health and that bacteriophages are frequently used as models of mammalian viruses, it is important to know and understand the mechanisms and photodynamic procedures involved in their photoinactivation. The aim of this review is to (i) summarize the main approaches developed until now for the photodynamic inactivation of bacteriophages and mammalian viruses and, (ii) discuss and compare the present state of the art of mammalian viruses PDI with phage photoinactivation, with special focus on the most relevant mechanisms, molecular targets and factors affecting the viral inactivation process.

  5. Photodynamic Inactivation of Mammalian Viruses and Bacteriophages

    Directory of Open Access Journals (Sweden)

    Liliana Costa

    2012-06-01

    Full Text Available Photodynamic inactivation (PDI has been used to inactivate microorganisms through the use of photosensitizers. The inactivation of mammalian viruses and bacteriophages by photosensitization has been applied with success since the first decades of the last century. Due to the fact that mammalian viruses are known to pose a threat to public health and that bacteriophages are frequently used as models of mammalian viruses, it is important to know and understand the mechanisms and photodynamic procedures involved in their photoinactivation. The aim of this review is to (i summarize the main approaches developed until now for the photodynamic inactivation of bacteriophages and mammalian viruses and, (ii discuss and compare the present state of the art of mammalian viruses PDI with phage photoinactivation, with special focus on the most relevant mechanisms, molecular targets and factors affecting the viral inactivation process.

  6. Photodynamic Inactivation of Mammalian Viruses and Bacteriophages

    Science.gov (United States)

    Costa, Liliana; Faustino, Maria Amparo F.; Neves, Maria Graça P. M. S.; Cunha, Ângela; Almeida, Adelaide

    2012-01-01

    Photodynamic inactivation (PDI) has been used to inactivate microorganisms through the use of photosensitizers. The inactivation of mammalian viruses and bacteriophages by photosensitization has been applied with success since the first decades of the last century. Due to the fact that mammalian viruses are known to pose a threat to public health and that bacteriophages are frequently used as models of mammalian viruses, it is important to know and understand the mechanisms and photodynamic procedures involved in their photoinactivation. The aim of this review is to (i) summarize the main approaches developed until now for the photodynamic inactivation of bacteriophages and mammalian viruses and, (ii) discuss and compare the present state of the art of mammalian viruses PDI with phage photoinactivation, with special focus on the most relevant mechanisms, molecular targets and factors affecting the viral inactivation process. PMID:22852040

  7. Using magnetic resonance imaging to monitor CH4 hydrate formation and spontaneous conversion of CH4 hydrate to CO2 hydrate in porous media.

    Science.gov (United States)

    Baldwin, Bernard A; Stevens, Jim; Howard, James J; Graue, Arne; Kvamme, Bjorn; Aspenes, Erick; Ersland, Geir; Husebø, Jarle; Zornes, David R

    2009-06-01

    Magnetic resonance imaging was used to monitor and quantify methane hydrate formation and exchange in porous media. Conversion of methane hydrate to carbon dioxide hydrate, when exposed to liquid carbon dioxide at 8.27 MPa and approximately 4 degrees C, was experimentally demonstrated with MRI data and verified by mass balance calculations of consumed volumes of gases and liquids. No detectable dissociation of the hydrate was measured during the exchange process.

  8. Controls on Gas Hydrate Formation and Dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Miriam Kastner; Ian MacDonald

    2006-03-03

    The main objectives of the project were to monitor, characterize, and quantify in situ the rates of formation and dissociation of methane hydrates at and near the seafloor in the northern Gulf of Mexico, with a focus on the Bush Hill seafloor hydrate mound; to record the linkages between physical and chemical parameters of the deposits over the course of one year, by emphasizing the response of the hydrate mound to temperature and chemical perturbations; and to document the seafloor and water column environmental impacts of hydrate formation and dissociation. For these, monitoring the dynamics of gas hydrate formation and dissociation was required. The objectives were achieved by an integrated field and laboratory scientific study, particularly by monitoring in situ formation and dissociation of the outcropping gas hydrate mound and of the associated gas-rich sediments. In addition to monitoring with the MOSQUITOs, fluid flow rates and temperature, continuously sampling in situ pore fluids for the chemistry, and imaging the hydrate mound, pore fluids from cores, peepers and gas hydrate samples from the mound were as well sampled and analyzed for chemical and isotopic compositions. In order to determine the impact of gas hydrate dissociation and/or methane venting across the seafloor on the ocean and atmosphere, the overlying seawater was sampled and thoroughly analyzed chemically and for methane C isotope ratios. At Bush hill the pore fluid chemistry varies significantly over short distances as well as within some of the specific sites monitored for 440 days, and gas venting is primarily focused. The pore fluid chemistry in the tub-warm and mussel shell fields clearly documented active gas hydrate and authigenic carbonate formation during the monitoring period. The advecting fluid is depleted in sulfate, Ca Mg, and Sr and is rich in methane; at the main vent sites the fluid is methane supersaturated, thus bubble plumes form. The subsurface hydrology exhibits both

  9. Solid state tungsten oxide hydrate/tin oxide hydrate electrochromic device prepared by electrochemical reactions

    Science.gov (United States)

    Nishiyama, Kentaro; Matsuo, Ryo; Sasano, Junji; Yokoyama, Seiji; Izaki, Masanobu

    2017-03-01

    The solid state electrochromic device composed of tungsten oxide hydrate (WO3(H2O)0.33) and tin oxide hydrate (Sn(O,OH)) has been constructed by anodic deposition of WO3(H2O)0.33 and Sn(O,OH) layers and showed the color change from clear to blue by applying voltage through an Au electrode.

  10. Kinetic studies of gas hydrate formation with low-dosage hydrate inhibitors

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Pipeline blockage by gas hydrates is a serious problem in the petroleum industry.Low-dosage inhibitors have been developed for its cost-effective and environmentally acceptable characteristics.In a 1.072-L reactor with methane,ethane and propane gas mixture under the pressure of about 8.5 MPa at 4 °C,hydrate formation was investigated with low-dosage hydrate inhibitors PVP and GHI1,the change of the compressibility factor and gas composition in the gas phase was analyzed,the gas contents in hydrates were compared with PVP and GHI1 added,and the inhibition mechanism of GHI1 was discussed.The results show that PVP and GHI1 could effectively inhibit the growth of gas hydrates but not nucleation.Under the experimental condition with PVP added,methane and ethane occupied the small cavities of the hydrate crystal unit and the ability of ethane entering into hydrate cavities was weaker than that of methane.GHI1 could effectively inhibit molecules which could more readily form hydrates.The ether and hydroxy group of diethylene glycol monobutyl ether have the responsibility for stronger inhibition ability of GHI1 than PVP.

  11. Experimental characterization of production behavior accompanying the hydrate reformation in methane hydrate bearing sediments

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, T.; Kang, J.M.; Nguyen, H.T. [Seoul National Univ., Seoul (Korea, Republic of); Park, C. [Kangwon National Univ., (Korea, Republic of); Lee, J. [Korea Inst., of Geoscience and Mineral Resources (Korea, Republic of)

    2010-07-01

    This study investigated the production behaviour associated with gas hydrate reformation in methane hydrate-bearing sediment by hot-brine injection. A range of different temperature and brine injection rates were used to analyze the pressure and temperature distribution, the gas production behaviour and the movement of the dissociation front. The study showed that hydrate reformation reduces the production rate considerably at an early time. However, gas production increases during the dissociation, near the outlet because the dissociated methane around the inlet is consumed in reforming the hydrate and increases the hydrate saturation around the outlet. Higher temperature also increases the gas production rate and the speed of the dissociation front. 12 refs., 2 tabs., 4 figs.

  12. Effect of formaldehyde inactivation on poliovirus.

    Science.gov (United States)

    Wilton, Thomas; Dunn, Glynis; Eastwood, David; Minor, Philip D; Martin, Javier

    2014-10-01

    Inactivated polio vaccines, which have been used in many countries for more than 50 years, are produced by treating live poliovirus (PV) with formaldehyde. However, the molecular mechanisms underlying virus inactivation are not well understood. Infection by PV is initiated by virus binding to specific cell receptors, which results in viral particles undergoing sequential conformational changes that generate altered structural forms (135S and 80S particles) and leads to virus cell entry. We have analyzed the ability of inactivated PV to bind to the human poliovirus receptor (hPVR) using various techniques such as ultracentrifugation, fluorescence-activated cell sorting flow cytometry and real-time reverse transcription-PCR (RT-PCR). The results showed that although retaining the ability to bind to hPVR, inactivated PV bound less efficiently in comparison to live PV. We also found that inactivated PV showed resistance to structural conversion in vitro, as judged by measuring changes in antigenicity, the ability to bind to hPVR, and viral RNA release at high temperature. Furthermore, viral RNA from inactivated PV was shown to be modified, since cDNA yields obtained by RT-PCR amplification were severely reduced and no infectious virus was recovered after RNA transfection into susceptible cells. Importance: This study represents a novel insight into the molecular mechanisms responsible for poliovirus inactivation. We show that inactivation with formaldehyde has an effect on early steps of viral replication as it reduces the ability of PV to bind to hPVR, decreases the sensitivity of PV to convert to 135S particles, and abolishes the infectivity of its viral RNA. These changes are likely responsible for the loss of infectivity shown by PV following inactivation. Techniques used in this study represent new approaches for the characterization of inactivated PV products and could be useful in developing improved methods for the production and quality control testing of

  13. Authigenic gypsum found in gas hydrate-associated sediments from Hydrate Ridge, the eastern North Pacific

    Institute of Scientific and Technical Information of China (English)

    WANG; Jiasheng; Erwin; Suess; Dirk; Rickert

    2004-01-01

    Characteristic gypsum micro-sphere and granular mass were discovered by binocular microscope in the gas hydrate-associated sediments at cores SO143-221 and SO143/TVG40-2A respectively on Hydrate Ridge of Cascadia margin, the eastern North Pacific. XRD patterns and EPA analyses show both micro-sphere and granular mass of the crystals have the typical peaks and the typical main chemical compositions of gypsum, although their weight percents are slightly less than the others in the non-gas hydrate-associated marine regions. SEM pictures show that the gypsum crystals have clear crystal boundaries, planes, edges and cleavages of gypsum in form either of single crystal or of twin crystals. In view of the fact that there are meanwhile gas hydrate-associated authigenic carbonates and SO42(-rich pore water in the same sediment cores, it could be inferred reasonably that the gypsums formed also authigenically in the gas hydrate-associated environment too, most probably at the interface between the downward advecting sulfate-rich seawater and the below gas hydrate, which spilled calcium during its formation on Hydrate Ridge. The two distinct forms of crystal intergrowth, which are the granular mass of series single gypsum crystals at core SO143/TVG40-2A and the microsphere of gypsum crystals accompanied with detrital components at core SO143-221 respectively, indicate that they precipitated most likely in different interstitial water dynamic environments. So, the distinct authigenic gypsums found in gas hydrate-associated sediments on Hydrate Ridge could also be believed as one of the parameters which could be used to indicate the presence of gas hydrate in an unknown marine sediment cores.

  14. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Richard Sigal; Kent Newsham; Thomas Williams; Barry Freifeld; Timothy Kneafsey; Carl Sondergeld; Shandra Rai; Jonathan Kwan; Stephen Kirby; Robert Kleinberg; Doug Griffin

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. The work scope drilled and cored a well The Hot Ice No. 1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report. The Hot Ice No. 1 well was drilled from the surface to a measured depth of 2300 ft. There was almost 100% core recovery from the bottom of surface casing at 107 ft to total depth. Based on the best estimate of the bottom of the methane hydrate stability zone (which used new data obtained from Hot Ice No. 1 and new analysis of data from adjacent wells), core was recovered over its complete range. Approximately 580 ft of porous, mostly frozen, sandstone and 155 of conglomerate were recovered in the Ugnu Formation and approximately 215 ft of porous sandstone were recovered in the West Sak Formation. There were gas shows in the bottom

  15. Experimental Determination of Refractive Index of Gas Hydrates

    DEFF Research Database (Denmark)

    Bylov, Martin; Rasmussen, Peter

    1997-01-01

    The refractive indexes of methane hydrate and natural gas hydrate have been experimentally determined. The refractive indexes were determined in an indirect manner making use of the fact that two non-absorbing materials will have the same refractive index if they cannot be distinguished visually....... For methane hydrate (structure I) the refractive index was found to be 1.346 and for natural gas hydrate (structure II) it was found to be 1.350. The measurements further suggest that the gas hydrate growth rate increases if the water has formed hydrates before. The induction time, on the other hand, seems...

  16. Complex admixtures of clathrate hydrates in a water desalination method

    Science.gov (United States)

    Simmons, Blake A.; Bradshaw, Robert W.; Dedrick, Daniel E.; Anderson, David W.

    2009-07-14

    Disclosed is a method that achieves water desalination by utilizing and optimizing clathrate hydrate phenomena. Clathrate hydrates are crystalline compounds of gas and water that desalinate water by excluding salt molecules during crystallization. Contacting a hydrate forming gaseous species with water will spontaneously form hydrates at specific temperatures and pressures through the extraction of water molecules from the bulk phase followed by crystallite nucleation. Subsequent dissociation of pure hydrates yields fresh water and, if operated correctly, allows the hydrate-forming gas to be efficiently recycled into the process stream.

  17. Correlation-Mediated Processes for Electron-Induced Switching between Néel States of Fe Antiferromagnetic Chains

    Science.gov (United States)

    Gauyacq, Jean-Pierre; Yaro, Simeón Moisés; Cartoixà, Xavier; Lorente, Nicolás

    2013-02-01

    The controlled switching between two quasistable Néel states in adsorbed antiferromagnetic Fe chains has recently been achieved by Loth et al. [Science 335, 196 (2012)SCIEAS0036-8075] using tunneling electrons from an STM tip. In order to rationalize their data, we evaluate the rate of tunneling electron-induced switching between the Néel states. Good agreement is found with the experiment, permitting us to identify three switching mechanisms: (i) low STM voltage direct electron-induced transitions, (ii) intermediate STM voltage switching via spin-wave-like excitation, and (iii) high STM voltage transitions mediated by domain-wall formation. Spin correlations in the antiferromagnetic chains are the switching driving force, leading to a marked chain-size dependence.

  18. Efficient electron-induced removal of oxalate ions and formation of copper nanoparticles from copper(II oxalate precursor layers

    Directory of Open Access Journals (Sweden)

    Kai Rückriem

    2016-06-01

    Full Text Available Copper(II oxalate grown on carboxy-terminated self-assembled monolayers (SAM using a step-by-step approach was used as precursor for the electron-induced synthesis of surface-supported copper nanoparticles. The precursor material was deposited by dipping the surfaces alternately in ethanolic solutions of copper(II acetate and oxalic acid with intermediate thorough rinsing steps. The deposition of copper(II oxalate and the efficient electron-induced removal of the oxalate ions was monitored by reflection absorption infrared spectroscopy (RAIRS. Helium ion microscopy (HIM reveals the formation of spherical nanoparticles with well-defined size and X-ray photoelectron spectroscopy (XPS confirms their metallic nature. Continued irradiation after depletion of oxalate does not lead to further particle growth giving evidence that nanoparticle formation is primarily controlled by the available amount of precursor.

  19. First-principles elasticity of monocarboaluminate hydrates

    KAUST Repository

    Moon, J.

    2014-07-01

    The elasticity of monocarboaluminate hydrates, 3CaO·Al2O3·CaCO3·xH2O (x = 11 or 8), has been investigated by first-principles calculations. Previous experimental study revealed that the fully hydrated monocarboaluminate (x = 11) exhibits exceptionally low compressibility compared to other reported calcium aluminate hydrates. This stiff hydration product can contribute to the strength of concrete made with Portland cements containing calcium carbonates. In this study, full elastic tensors and mechanical properties of the crystal structures with different water contents (x = 11 or 8) are computed by first-principles methods based on density functional theory. The results indicate that the compressibility of monocarboaluminate is highly dependent on the water content in the interlayer region. The structure also becomes more isotropic with the addition of water molecules in this region. Since the monocarboaluminate is a key hydration product of limestone added cement, elasticity of the crystal is important to understand its mechanical impact on concrete. Besides, it is put forth that this theoretical calculation will be useful in predicting the elastic properties of other complex cementitous materials and the influence of ion exchange on compressibility.

  20. Interfacial phenomena in gas hydrate systems.

    Science.gov (United States)

    Aman, Zachary M; Koh, Carolyn A

    2016-03-21

    Gas hydrates are crystalline inclusion compounds, where molecular cages of water trap lighter species under specific thermodynamic conditions. Hydrates play an essential role in global energy systems, as both a hinderance when formed in traditional fuel production and a substantial resource when formed by nature. In both traditional and unconventional fuel production, hydrates share interfaces with a tremendous diversity of materials, including hydrocarbons, aqueous solutions, and inorganic solids. This article presents a state-of-the-art understanding of hydrate interfacial thermodynamics and growth kinetics, and the physiochemical controls that may be exerted on both. Specific attention is paid to the molecular structure and interactions of water, guest molecules, and hetero-molecules (e.g., surfactants) near the interface. Gas hydrate nucleation and growth mechanics are also presented, based on studies using a combination of molecular modeling, vibrational spectroscopy, and X-ray and neutron diffraction. The fundamental physical and chemical knowledge and methods presented in this review may be of value in probing parallel systems of crystal growth in solid inclusion compounds, crystal growth modifiers, emulsion stabilization, and reactive particle flow in solid slurries.

  1. Stability evaluation of hydrate-bearing sediments during thermally-driven hydrate dissociation

    Science.gov (United States)

    Kwon, T.; Cho, G.; Santamarina, J.; Kim, H.; Lee, J.

    2009-12-01

    Hydrate-bearing sediments may destabilize spontaneously as part of geological processes, unavoidably during petroleum drilling/production operations, or intentionally as part of gas extraction from the hydrate itself. In all cases, high pore fluid pressure generation is anticipated during hydrate dissociation. This study examined how thermal changes destabilize gas hydrate-bearing sediments. First, an analytical formulation was derived for predicting fluid pressure evolution in hydrate-bearing sediments subjected to thermal stimulation without mass transfer. The formulation captures the self-preservation behavior, calculates the hydrate and free gas quantities during dissociation, considering effective stress-controlled sediment compressibility and gas solubility in aqueous phase. Pore fluid pressure generation is proportional to the initial hydrate fraction and the sediment bulk stiffness; is inversely proportional to the initial gas fraction and gas solubility; and is limited by changes in effective stress that cause the failure of the sediment. Second, the analytical formulation for hydrate dissociation was incorporated as a user-defined function into a verified finite difference code (FLAC2D). The underlying physical processes of hydrate-bearing sediments, including hydrate dissociation, self-preservation, pore pressure evolution, gas dissolution, and sediment volume expansion, were coupled with the thermal conduction, pore fluid flow, and mechanical response of sediments. We conducted the simulations for a duration of 20 years, assuming a constant-temperature wellbore transferred heat to the surrounding hydrate-bearing sediments, resulting in dissociation of methane hydrate in the well vicinity. The model predicted dissociation-induced excess pore fluid pressures which resulted in a large volume expansion and plastic deformation of the sediments. Furthermore, when the critical stress was reached, localized shear failure of the sediment around the borehole was

  2. Dynamics of surface-migration: Electron-induced reaction of 1,2-dihaloethanes on Si(100)

    Science.gov (United States)

    Huang, Kai; MacLean, Oliver; Guo, Si Yue; McNab, Iain R.; Ning, Zhanyu; Wang, Chen-Guang; Ji, Wei; Polanyi, John C.

    2016-10-01

    Scanning Tunneling Microscopy was used to investigate the electron-induced reaction of 1,2-dibromoethane (DBE) and 1,2-dichloroethane (DCE) on Si(100).We observed a long-lived physisorbed molecular state of DBE at 75 K and of DCE at 110 K. As a result we were able to characterize by experiment and also by ab initio theory the dynamics of ethylene production in the electron-induced surface-reaction of these physisorbed species. For both DBE and DCE the ethylene product was observed to migrate across the surface. In the case of DBE the recoil of the ethylene favored the silicon rows, migrating by an average distance of 22 Å, and up to 100 Å. Trajectory calculations were performed for this electron-induced reaction, using an 'Impulsive Two-State' model involving an anionic excited state and a neutral ground-potential. The model agreed with experiment in reproducing both migration and desorption of the ethylene product. The computed migration exhibited a 'ballistic' launch and subsequent 'bounces', thereby accounting for the observed long-range migratory dynamics.

  3. Inactivation of a solid-state detergent protease by hydrogen peroxide vapor and humidity.

    Science.gov (United States)

    Biran, Suzan; Jensen, Anker Degn; Kiil, Søren; Bach, Poul; Simonsen, Ole

    2009-04-20

    An experimental study on solid-state stability of a detergent protease (Savinase) is reported. The inactivation kinetics of technical grade enzyme powder was determined as a function of gas phase H(2)O(2) concentration and humidity by employing a quick assay running over few hours instead of several weeks as typical in industry. The results indicated that enzymes adsorbed significant amounts of moisture and H(2)O(2) during exposure. The amount of adsorbed H(2)O(2) did not depend on humidity in the gas stream, which implied that water and H(2)O(2) were not competing for the same adsorption sites. Inactivation of the solid-state enzyme was caused by the mutual effect of increasing hydration and H(2)O(2) (g) concentration. No auto-proteolytic activity or covalently bound aggregate formation was detected. A simple mechanism for solid-state enzyme oxidation was proposed and the kinetic parameters in the resulting rate expression of inactivation were derived. A good agreement between the derived equation and experimental data was obtained. The oxidative alterations on Savinase were investigated by peptide mapping. Molecular mass examination of CNBr-cleaved fragments by MALDI-TOF mass spectroscopy located the oxidation-labile residue. Only one methionine (Met 222) was oxidized, while other residues remained unaffected. The study provides practical information on solid-state stability measurements of biocatalysts in oxidative environments.

  4. Methane hydrates in nature - Current knowledge and challenges

    Science.gov (United States)

    Collett, Timothy S.

    2014-01-01

    Recognizing the importance of methane hydrate research and the need for a coordinated effort, the United States Congress enacted the Methane Hydrate Research and Development Act of 2000. At the same time, the Ministry of International Trade and Industry in Japan launched a research program to develop plans for a methane hydrate exploratory drilling project in the Nankai Trough. India, China, the Republic of Korea, and other nations also have established large methane hydrate research and development programs. Government-funded scientific research drilling expeditions and production test studies have provided a wealth of information on the occurrence of methane hydrates in nature. Numerous studies have shown that the amount of gas stored as methane hydrates in the world may exceed the volume of known organic carbon sources. However, methane hydrates represent both a scientific and technical challenge, and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of methane hydrates in nature, (2) assessing the volume of natural gas stored within various methane hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural methane hydrates, (5) analyzing the methane hydrate role as a geohazard, (6) establishing the means to detect and characterize methane hydrate accumulations using geologic and geophysical data, and (7) establishing the thermodynamic phase equilibrium properties of methane hydrates as a function of temperature, pressure, and gas composition. The U.S. Department of Energy (DOE) and the Consortium for Ocean Leadership (COL) combined their efforts in 2012 to assess the contributions that scientific drilling has made and could continue to make to advance

  5. Apparatus investigates geological aspects of gas hydrates

    Science.gov (United States)

    Booth, J.S.; Winters, W.J.; Dillon, William P.

    1999-01-01

    The US Geological Survey has developed a laboratory research system which allows the study of the creation and dissociation of gas hydrates under deepwater conditions and with different sediment types and pore fluids. The system called GHASTLI (gas hydrate and sediment test laboratory instrument) comprises a pressure chamber which holds a sediment specimen, and which can simulate water depths to 2,500m and different sediment overburden. Seawater and gas flow through a sediment specimen can be precisely controlled and monitored. It can simulate a wide range of geology and processes and help to improve understanding of gas hydrate processes and aid prediction of geohazards, their control and potential use as an energy source. This article describes GHASTLI and how it is able to simulate natural conditions, focusing on fluid volume, acoustic velocity-compressional and shear wave, electric resistance, temperature, pore pressure, shear strength, and permeability.

  6. Simulation of Methane Recovery from Gas Hydrates Combined with Storing Carbon Dioxide as Hydrates

    Directory of Open Access Journals (Sweden)

    Georg Janicki

    2011-01-01

    Full Text Available In the medium term, gas hydrate reservoirs in the subsea sediment are intended as deposits for carbon dioxide (CO2 from fossil fuel consumption. This idea is supported by the thermodynamics of CO2 and methane (CH4 hydrates and the fact that CO2 hydrates are more stable than CH4 hydrates in a certain P-T range. The potential of producing methane by depressurization and/or by injecting CO2 is numerically studied in the frame of the SUGAR project. Simulations are performed with the commercial code STARS from CMG and the newly developed code HyReS (hydrate reservoir simulator especially designed for hydrate processing in the subsea sediment. HyReS is a nonisothermal multiphase Darcy flow model combined with thermodynamics and rate kinetics suitable for gas hydrate calculations. Two scenarios are considered: the depressurization of an area 1,000 m in diameter and a one/two-well scenario with CO2 injection. Realistic rates for injection and production are estimated, and limitations of these processes are discussed.

  7. Ribosome Inactivating Proteins from Rosaceae.

    Science.gov (United States)

    Shang, Chenjing; Rougé, Pierre; Van Damme, Els J M

    2016-08-22

    Ribosome-inactivating proteins (RIPs) are widespread among higher plants of different taxonomic orders. In this study, we report on the RIP sequences found in the genome/transcriptome of several important Rosaceae species, including many economically important edible fruits such as apple, pear, peach, apricot, and strawberry. All RIP domains from Rosaceae share high sequence similarity with conserved residues in the catalytic site and the carbohydrate binding sites. The genomes of Malus domestica and Pyrus communis contain both type 1 and type 2 RIP sequences, whereas for Prunus mume, Prunus persica, Pyrus bretschneideri, and Pyrus communis a complex set of type 1 RIP sequences was retrieved. Heterologous expression and purification of the type 1 as well as the type 2 RIP from apple allowed to characterize the biological activity of the proteins. Both RIPs from Malus domestica can inhibit protein synthesis. Furthermore, molecular modelling suggests that RIPs from Rosaceae possess three-dimensional structures that are highly similar to the model proteins and can bind to RIP substrates. Screening of the recombinant type 2 RIP from apple on a glycan array revealed that this type 2 RIP interacts with terminal sialic acid residues. Our data suggest that the RIPs from Rosaceae are biologically active proteins.

  8. Population Dynamics of Viral Inactivation

    Science.gov (United States)

    Freeman, Krista; Li, Dong; Behrens, Manja; Streletzky, Kiril; Olsson, Ulf; Evilevitch, Alex

    We have investigated the population dynamics of viral inactivation in vitrousing time-resolved cryo electron microscopy combined with light and X-ray scattering techniques. Using bacteriophage λ as a model system for pressurized double-stranded DNA viruses, we found that virions incubated with their cell receptor eject their genome in a stochastic triggering process. The triggering of DNA ejection occurs in a non synchronized manner after the receptor addition, resulting in an exponential decay of the number of genome-filled viruses with time. We have explored the characteristic time constant of this triggering process at different temperatures, salt conditions, and packaged genome lengths. Furthermore, using the temperature dependence we determined an activation energy for DNA ejections. The dependences of the time constant and activation energy on internal DNA pressure, affected by salt conditions and encapsidated genome length, suggest that the triggering process is directly dependent on the conformational state of the encapsidated DNA. The results of this work provide insight into how the in vivo kinetics of the spread of viral infection are influenced by intra- and extra cellular environmental conditions. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1252522.

  9. Nanostructure of Calcium Silicate Hydrates in Cements

    KAUST Repository

    Skinner, L. B.

    2010-05-11

    Calcium silicate hydrate (CSH) is the major volume phase in the matrix of Portland cement concrete. Total x-ray scattering measurements with synchrotron x rays on synthetic CSH(I) shows nanocrystalline ordering with a particle diameter of 3.5(5) nm, similar to a size-broadened 1.1 nm tobermorite crystal structure. The CSH component in hydrated tricalcium silicate is found to be similar to CSH(I). Only a slight bend and additional disorder within the CaO sheets is required to explain its nanocrystalline structure. © 2010 The American Physical Society.

  10. Simulation of subsea gas hydrate exploitation

    Science.gov (United States)

    Janicki, Georg; Schlüter, Stefan; Hennig, Torsten; Deerberg, Görge

    2014-05-01

    The recovery of methane from gas hydrate layers that have been detected in several subsea sediments and permafrost regions around the world is a promising perspective to overcome future shortages in natural gas supply. Being aware that conventional natural gas resources are limited, research is going on to develop technologies for the production of natural gas from such new sources. Thus various research programs have started since the early 1990s in Japan, USA, Canada, India, and Germany to investigate hydrate deposits and develop required technologies. In recent years, intensive research has focussed on the capture and storage of CO2 from combustion processes to reduce climate impact. While different natural or man-made reservoirs like deep aquifers, exhausted oil and gas deposits or other geological formations are considered to store gaseous or liquid CO2, the storage of CO2 as hydrate in former methane hydrate fields is another promising alternative. Due to beneficial stability conditions, methane recovery may be well combined with CO2 storage in the form of hydrates. Regarding technological implementation many problems have to be overcome. Especially mixing, heat and mass transfer in the reservoir are limiting factors causing very long process times. Within the scope of the German research project »SUGAR« different technological approaches for the optimized exploitation of gas hydrate deposits are evaluated and compared by means of dynamic system simulations and analysis. Detailed mathematical models for the most relevant chemical and physical processes are developed. The basic mechanisms of gas hydrate formation/dissociation and heat and mass transport in porous media are considered and implemented into simulation programs. Simulations based on geological field data have been carried out. The studies focus on the potential of gas production from turbidites and their fitness for CO2 storage. The effects occurring during gas production and CO2 storage within

  11. GLASS TRANSITION OF HYDRATED WHEAT GLIADIN POWDERS

    Institute of Scientific and Technical Information of China (English)

    Shao-min Sun; Li Zhao; Yi-hu Song; Qiang Zheng

    2011-01-01

    Modulated-temperature differential scanning calorimetric and dynamic mechanical analyses and dielectric spectroscopy were used to investigate the glass transition of hydrated wheat gliadin powders with moisture absorption ranged from 2.30 db% to 18.21 db%. Glass transition temperature (Tg) of dry wheat gliadin was estimated according to the GordonTaylor equation. Structural heterogeneity at high degrees of hydration was revealed in dielectric temperature and frequency spectra. The activation energies (Ea) of the two relaxations were calculated from Arrhenius equation.

  12. Component analysis of the protein hydration entropy

    Science.gov (United States)

    Chong, Song-Ho; Ham, Sihyun

    2012-05-01

    We report the development of an atomic decomposition method of the protein solvation entropy in water, which allows us to understand global change in the solvation entropy in terms of local changes in protein conformation as well as in hydration structure. This method can be implemented via a combined approach based on molecular dynamics simulation and integral-equation theory of liquids. An illustrative application is made to 42-residue amyloid-beta protein in water. We demonstrate how this method enables one to elucidate the molecular origin for the hydration entropy change upon conformational transitions of protein.

  13. Inactivation of jack bean urease by allicin.

    Science.gov (United States)

    Juszkiewicz, Adam; Zaborska, Wiesława; Sepioł, Janusz; Góra, Maciej; Zaborska, Anna

    2003-10-01

    Allicin--diallyl thiosulfinate--is the main biologically active component of freshly crushed garlic. Allicin was synthesized as described elsewhere and was tested for its inhibitory ability against jack bean urease in 20 mM phosphate buffer, pH 7.0 at 22 degrees C. The results indicate that allicin is an enzymatic inactivator. The loss of urease activity was irreversible, time- and concentration dependent and the kinetics of the inactivation was biphasic; each phase, obeyed pseudo-first-order kinetics. The rate constants for inactivation were measured for the fast and slow phases and for several concentrations of allicin. Thiol reagents, and competitive inhibitor (boric acid) protected the enzyme from loss of enzymatic activity. The studies demonstrate that urease inactivation results from the reaction between allicin and the SH-group, situated in the urease active site (Cys592).

  14. Photosensitizers mediated photodynamic inactivation against virus particles.

    Science.gov (United States)

    Sobotta, Lukasz; Skupin-Mrugalska, Paulina; Mielcarek, Jadwiga; Goslinski, Tomasz; Balzarini, Jan

    2015-01-01

    Viruses cause many diseases in humans from the rather innocent common cold to more serious or chronic, life-threatening infections. The long-term side effects, sometimes low effectiveness of standard pharmacotherapy and the emergence of drug resistance require a search for new alternative or complementary antiviral therapeutic approaches. One new approach to inactivate microorganisms is photodynamic antimicrobial chemotherapy (PACT). PACT has evolved as a potential method to inactivate viruses. The great challenge for PACT is to develop a methodology enabling the effective inactivation of viruses while leaving the host cells as untouched as possible. This review aims to provide some main directions of antiviral PACT, taking into account different photosensitizers, which have been widely investigated as potential antiviral agents. In addition, several aspects concerning PACT as a tool to assure viral inactivation in human blood products will be addressed.

  15. Gas hydrate of Lake Baikal: Discovery and varieties

    Science.gov (United States)

    Khlystov, Oleg; De Batist, Marc; Shoji, Hitoshi; Hachikubo, Akihiro; Nishio, Shinya; Naudts, Lieven; Poort, Jeffrey; Khabuev, Andrey; Belousov, Oleg; Manakov, Andrey; Kalmychkov, Gennаdy

    2013-01-01

    This paper summarizes the results of recent gas-hydrate studies in Lake Baikal, the only fresh-water lake in the world containing gas hydrates in its sedimentary infill. We provide a historical overview of the different investigations and discoveries and highlight some recent breakthroughs in our understanding of the Baikal hydrate system. So far, 21 sites of gas hydrate occurrence have been discovered. Gas hydrates are of structures I and II, which are of thermogenic, microbial, and mixed origin. At the 15 sites, gas hydrates were found in mud volcanoes, and the rest six - near gas discharges. Additionally, depending on type of discharge and gas hydrate structure, they were visually different. Investigations using MIR submersibles allowed finding of gas hydrates at the bottom surface of Lake Baikal at the three sites.

  16. Microbial Inactivation by Ultrasound Assisted Supercritical Fluids

    Science.gov (United States)

    Benedito, Jose; Ortuño, Carmen; Castillo-Zamudio, Rosa Isela; Mulet, Antonio

    A method combining supercritical carbon dioxide (SC-CO2) and high power ultrasound (HPU) has been developed and tested for microbial/enzyme inactivation purposes, at different process conditions for both liquid and solid matrices. In culture media, using only SC-CO2, the inactivation rate of E. coli and S. cerevisiae increased with pressure and temperature; and the total inactivation (7-8 log-cycles) was attained after 25 and 140 min of SC-CO2 (350 bar, 36 °C) treatment, respectively. Using SC-CO2+HPU, the time for the total inactivation of both microorganisms was reduced to only 1-2 min, at any condition selected. The SC-CO2+HPU inactivation of both microorganisms was slower in juices (avg. 4.9 min) than in culture media (avg. 1.5 min). In solid samples (chicken, turkey ham and dry-cured pork cured ham) treated with SC-CO2 and SC-CO2+HPU, the inactivation rate of E. coli increased with temperature. The application of HPU to the SC-CO2 treatments accelerated the inactivation rate of E. coli and that effect was more pronounced in treatments with isotonic solution surrounding the solid food samples. The application of HPU enhanced the SC-CO2 inactivation mechanisms of microorganisms, generating a vigorous agitation that facilitated the CO2 solubilization and the mass transfer process. The cavitation generated by HPU could damage the cell walls accelerating the extraction of vital constituents and the microbial death. Thus, using the combined technique, reasonable industrial processing times and mild process conditions could be used which could result into a cost reduction and lead to the minimization in the food nutritional and organoleptic changes.

  17. Inactivation of Viruses by Benzalkonium Chloride

    Science.gov (United States)

    Armstrong, J. A.; Froelich, E. J.

    1964-01-01

    Benzalkonium chloride (as Roccal or Zephiran) was found to inactivate influenza, measles, canine distemper, rabies, fowl laryngotracheitis, vaccinia, Semliki Forest, feline pneumonitis, meningopneumonitis, and herpes simplex viruses after 10 min of exposure at 30 C or at room temperature. Poliovirus and encephalomyocarditis virus were not inactivated under the same conditions. It was concluded that all viruses tested were sensitive except members of the picorna group. The literature was reviewed. PMID:4288740

  18. Inactivation of human myeloperoxidase by hydrogen peroxide.

    Science.gov (United States)

    Paumann-Page, Martina; Furtmüller, Paul G; Hofbauer, Stefan; Paton, Louise N; Obinger, Christian; Kettle, Anthony J

    2013-11-01

    Human myeloperoxidase (MPO) uses hydrogen peroxide generated by the oxidative burst of neutrophils to produce an array of antimicrobial oxidants. During this process MPO is irreversibly inactivated. This study focused on the unknown role of hydrogen peroxide in this process. When treated with low concentrations of H2O2 in the absence of reducing substrates, there was a rapid loss of up to 35% of its peroxidase activity. Inactivation is proposed to occur via oxidation reactions of Compound I with the prosthetic group or amino acid residues. At higher concentrations hydrogen peroxide acts as a suicide substrate with a rate constant of inactivation of 3.9 × 10(-3) s(-1). Treatment of MPO with high H2O2 concentrations resulted in complete inactivation, Compound III formation, destruction of the heme groups, release of their iron, and detachment of the small polypeptide chain of MPO. Ten of the protein's methionine residues were oxidized and the thermal stability of the protein decreased. Inactivation by high concentrations of H2O2 is proposed to occur via the generation of reactive oxidants when H2O2 reacts with Compound III. These mechanisms of inactivation may occur inside neutrophil phagosomes when reducing substrates for MPO become limiting and could be exploited when designing pharmacological inhibitors.

  19. Hydrate bearing clayey sediments: Formation and gas production concepts

    KAUST Repository

    Jang, Jaewon

    2016-06-20

    Hydro-thermo-chemo and mechanically coupled processes determine hydrate morphology and control gas production from hydrate-bearing sediments. Force balance, together with mass and energy conservation analyses anchored in published data provide robust asymptotic solutions that reflect governing processes in hydrate systems. Results demonstrate that hydrate segregation in clayey sediments results in a two-material system whereby hydrate lenses are surrounded by hydrate-free water-saturated clay. Hydrate saturation can reach ≈2% by concentrating the excess dissolved gas in the pore water and ≈20% from metabolizable carbon. Higher hydrate saturations are often found in natural sediments and imply methane transport by advection or diffusion processes. Hydrate dissociation is a strongly endothermic event; the available latent heat in a reservoir can sustain significant hydrate dissociation without triggering ice formation during depressurization. The volume of hydrate expands 2-to-4 times upon dissociation or CO2single bondCH4 replacement. Volume expansion can be controlled to maintain lenses open and to create new open mode discontinuities that favor gas recovery. Pore size is the most critical sediment parameter for hydrate formation and gas recovery and is controlled by the smallest grains in a sediment. Therefore any characterization must carefully consider the amount of fines and their associated mineralogy.

  20. Foam drilling in natural gas hydrate

    Directory of Open Access Journals (Sweden)

    Wei Na

    2015-01-01

    Full Text Available The key problem of foam drilling in natural gas hydrate is prediction of characteristic parameters of bottom hole. The simulation shows that when the well depth increases, the foam mass number reduces and the pressure increases. At the same depth, pressure in drill string is always higher than annulus. The research findings provide theoretical basis for safety control.

  1. Alkali binding in hydrated Portland cement paste

    NARCIS (Netherlands)

    Chen, W.; Brouwers, H.J.H.

    2010-01-01

    The alkali-binding capacity of C–S–H in hydrated Portland cement pastes is addressed in this study. The amount of bound alkalis in C–S–H is computed based on the alkali partition theories firstly proposed by Taylor (1987) and later further developed by Brouwers and Van Eijk (2003). Experimental data

  2. A positron annihilation study of hydrated DNA

    DEFF Research Database (Denmark)

    Warman, J. M.; Eldrup, Morten Mostgaard

    1986-01-01

    Positron annihilation measurements are reported for hydrated DNA as a function of water content and as a function of temperature (20 to -180.degree. C) for samples containing 10 and 50% wt of water. The ortho-positronium mean lifetime and its intensity show distinct variations with the degree...

  3. Hydration of protein–RNA recognition sites

    Science.gov (United States)

    Barik, Amita; Bahadur, Ranjit Prasad

    2014-01-01

    We investigate the role of water molecules in 89 protein–RNA complexes taken from the Protein Data Bank. Those with tRNA and single-stranded RNA are less hydrated than with duplex or ribosomal proteins. Protein–RNA interfaces are hydrated less than protein–DNA interfaces, but more than protein–protein interfaces. Majority of the waters at protein–RNA interfaces makes multiple H-bonds; however, a fraction do not make any. Those making H-bonds have preferences for the polar groups of RNA than its partner protein. The spatial distribution of waters makes interfaces with ribosomal proteins and single-stranded RNA relatively ‘dry’ than interfaces with tRNA and duplex RNA. In contrast to protein–DNA interfaces, mainly due to the presence of the 2′OH, the ribose in protein–RNA interfaces is hydrated more than the phosphate or the bases. The minor groove in protein–RNA interfaces is hydrated more than the major groove, while in protein–DNA interfaces it is reverse. The strands make the highest number of water-mediated H-bonds per unit interface area followed by the helices and the non-regular structures. The preserved waters at protein–RNA interfaces make higher number of H-bonds than the other waters. Preserved waters contribute toward the affinity in protein–RNA recognition and should be carefully treated while engineering protein–RNA interfaces. PMID:25114050

  4. Binding Hydrated Anions with Hydrophobic Pockets.

    Science.gov (United States)

    Sokkalingam, Punidha; Shraberg, Joshua; Rick, Steven W; Gibb, Bruce C

    2016-01-13

    Using a combination of isothermal titration calorimetry and quantum and molecular dynamics calculations, we demonstrate that relatively soft anions have an affinity for hydrophobic concavity. The results are consistent with the anions remaining partially hydrated upon binding, and suggest a novel strategy for anion recognition.

  5. Obsidian Hydration Dating in the Undergraduate Curriculum.

    Science.gov (United States)

    Manche, Emanuel P.; Lakatos, Stephen

    1986-01-01

    Provides an overview of obsidian hydration dating for the instructor by presenting: (1) principles of the method; (2) procedures; (3) applications; and (4) limitations. The theory of the method and one or more laboratory exercises can be easily introduced into the undergraduate geology curriculum. (JN)

  6. Obsidian Hydration Dating in the Undergraduate Curriculum.

    Science.gov (United States)

    Manche, Emanuel P.; Lakatos, Stephen

    1986-01-01

    Provides an overview of obsidian hydration dating for the instructor by presenting: (1) principles of the method; (2) procedures; (3) applications; and (4) limitations. The theory of the method and one or more laboratory exercises can be easily introduced into the undergraduate geology curriculum. (JN)

  7. [Terminal phase hydration, pain and delirium

    DEFF Research Database (Denmark)

    Heick, A.

    2009-01-01

    Hydration of the terminal patient may relieve confusion and complaints of "dry mouth". But it may worsen oedema of the brain, lungs, and extremities, worsen terminal rattling and cause a need for frequent changing of diapers. The decision of whether and how to treat a dying patient with fluids...

  8. Acoustic Determination of Methane Hydrate Disssociation Pressures

    Science.gov (United States)

    2011-07-01

    centered- cubic orientation which forms naturally in deep oceans from biogenic gases. It is worth not- ing that this molecular geometry can trap great...until January 2010. At that time, the hydrates were packed in a dewar with liquid nitrogen and shipped from the storage fa- cility at the Naval Research

  9. Hydration of Acetylene: A 125th Anniversary

    Science.gov (United States)

    Ponomarev, Dmitry A.; Shevchenko, Sergey M.

    2007-01-01

    The year 2006 is the 125th anniversary of a chemical reaction, the discovery of which by Mikhail Kucherov had a profound effect on the development of industrial chemistry in the 19-20th centuries. This was the hydration of alkynes catalyzed by mercury ions that made possible industrial production of acetaldehyde from acetylene. Historical…

  10. Hydration dynamics near a model protein surface

    Energy Technology Data Exchange (ETDEWEB)

    Russo, Daniela; Hura, Greg; Head-Gordon, Teresa

    2003-09-01

    The evolution of water dynamics from dilute to very high concentration solutions of a prototypical hydrophobic amino acid with its polar backbone, N-acetyl-leucine-methylamide (NALMA), is studied by quasi-elastic neutron scattering and molecular dynamics simulation for both the completely deuterated and completely hydrogenated leucine monomer. We observe several unexpected features in the dynamics of these biological solutions under ambient conditions. The NALMA dynamics shows evidence of de Gennes narrowing, an indication of coherent long timescale structural relaxation dynamics. The translational water dynamics are analyzed in a first approximation with a jump diffusion model. At the highest solute concentrations, the hydration water dynamics is significantly suppressed and characterized by a long residential time and a slow diffusion coefficient. The analysis of the more dilute concentration solutions takes into account the results of the 2.0M solution as a model of the first hydration shell. Subtracting the first hydration layer based on the 2.0M spectra, the translational diffusion dynamics is still suppressed, although the rotational relaxation time and residential time are converged to bulk-water values. Molecular dynamics analysis shows spatially heterogeneous dynamics at high concentration that becomes homogeneous at more dilute concentrations. We discuss the hydration dynamics results of this model protein system in the context of glassy systems, protein function, and protein-protein interfaces.

  11. Anaerobic oxidation of methane above gas hydrates at Hydrate Ridge, NE Pacific Ocean

    DEFF Research Database (Denmark)

    Treude, T.; Boetius, A.; Knittel, K.;

    2003-01-01

    At Hydrate Ridge (HR), Cascadia convergent margin, surface sediments contain massive gas hydrates formed from methane that ascends together with fluids along faults from deeper reservoirs. Anaerobic oxidation of methane (AOM), mediated by a microbial consortium of archaea and sulfate-reducing...... bacteria, generates high concentrations of hydrogen sulfide in the surface sediments. The production of sulfide supports chemosynthetic communities that gain energy from sulfide oxidation. Depending on fluid flow, the surface communities are dominated either by the filamentous sulfur bacteria Beggiatoa...

  12. Modeling DNA hydration: comparison of calculated and experimental hydration properties of nuclic acid bases.

    Science.gov (United States)

    Poltev, V I; Malenkov, G G; Gonzalez, E J; Teplukhin, A V; Rein, R; Shibata, M; Miller, J H

    1996-02-01

    Hydration properties of individual nucleic acid bases were calculated and compared with the available experimental data. Three sets of classical potential functions (PF) used in simulations of nucleic acid hydration were juxtaposed: (i) the PF developed by Poltev and Malenkov (PM), (ii) the PF of Weiner and Kollman (WK), which together with Jorgensen's TIP3P water model are widely used in the AMBER program, and (iii) OPLS (optimized potentials for liquid simulations) developed by Jorgensen (J). The global minima of interaction energy of single water molecules with all the natural nucleic acid bases correspond to the formation of two water-base hydrogen bonds (water bridging of two hydrophilic atoms of the base). The energy values of these minima calculated via PM potentials are in somewhat better conformity with mass-spectrometric data than the values calculated via WK PF. OPLS gave much weaker water-base interactions for all compounds considered, thus these PF were not used in further computations. Monte Carlo simulations of the hydration of 9-methyladenine, 1-methyluracil and 1-methylthymine were performed in systems with 400 water molecules and periodic boundary conditions. Results of simulations with PM potentials give better agreement with experimental data on hydration energies than WK PF. Computations with PM PF of the hydration energy of keto and enol tautomers of 9-methylguanine can account for the shift in the tautomeric equilibrium of guanine in aqueous media to a dominance of the keto form in spite of nearly equal intrinsic stability of keto and enol tautomers. The results of guanine hydration computations are discussed in relation to mechanisms of base mispairing errors in nucleic acid biosynthesis. The data presented in this paper along with previous results on simulation of hydration shell structures in DNA duplex grooves provide ample evidence for the advantages of PM PF in studies of nucleic-acid hydration.

  13. Inactivation of pathogenic bacteria in food matrices: high pressure processing, photodynamic inactivation and pressure-assisted photodynamic inactivation

    Science.gov (United States)

    Cunha, A.; Couceiro, J.; Bonifácio, D.; Martins, C.; Almeida, A.; Neves, M. G. P. M. S.; Faustino, M. A. F.; Saraiva, J. A.

    2017-09-01

    Traditional food processing methods frequently depend on the application of high temperature. However, heat may cause undesirable changes in food properties and often has a negative impact on nutritional value and organoleptic characteristics. Therefore, reducing the microbial load without compromising the desirable properties of food products is still a technological challenge. High-pressure processing (HPP) can be classified as a cold pasteurization technique, since it is a non-thermal food preservation method that uses hydrostatic pressure to inactivate spoilage microorganisms. At the same time, it increases shelf life and retains the original features of food. Photodynamic inactivation (PDI) is also regarded as promising approach for the decontamination of food matrices. In this case, the inactivation of bacterial cells is achieved by the cytotoxic effects of reactive oxygens species (ROS) produced from the combined interaction of a photosensitizer molecule, light and oxygen. This short review examines some recent developments on the application of HPP and PDI with food-grade photosensitizers for the inactivation of listeriae, taken as a food pathogen model. The results of a proof-of-concept trial of the use of high-pressure as a coadjutant to increase the efficiency of photodynamic inactivation of bacterial endospores is also addressed.

  14. Direct measurement of methane hydrate composition along the hydrate equilibrium boundary

    Science.gov (United States)

    Circone, S.; Kirby, S.H.; Stern, L.A.

    2005-01-01

    The composition of methane hydrate, namely nW for CH 4??nWH2O, was directly measured along the hydrate equilibrium boundary under conditions of excess methane gas. Pressure and temperature conditions ranged from 1.9 to 9.7 MPa and 263 to 285 K. Within experimental error, there is no change in hydrate composition with increasing pressure along the equilibrium boundary, but nW may show a slight systematic decrease away from this boundary. A hydrate stoichiometry of n W = 5.81-6.10 H2O describes the entire range of measured values, with an average composition of CH4??5.99(??0.07) H2O along the equilibrium boundary. These results, consistent with previously measured values, are discussed with respect to the widely ranging values obtained by thermodynamic analysis. The relatively constant composition of methane hydrate over the geologically relevant pressure and temperature range investigated suggests that in situ methane hydrate compositions may be estimated with some confidence. ?? 2005 American Chemical Society.

  15. Clathrate Hydrates for Thermal Energy Storage in Buildings: Overview of Proper Hydrate-Forming Compounds

    Directory of Open Access Journals (Sweden)

    Beatrice Castellani

    2014-09-01

    Full Text Available Increasing energy costs are at the origin of the great progress in the field of phase change materials (PCMs. The present work aims at studying the application of clathrate hydrates as PCMs in buildings. Clathrate hydrates are crystalline structures in which guest molecules are enclosed in the crystal lattice of water molecules. Clathrate hydrates can form also at ambient pressure and present a high latent heat, and for this reason, they are good candidates for being used as PCMs. The parameter that makes a PCM suitable to be used in buildings is, first of all, a melting temperature at about 25 °C. The paper provides an overview of groups of clathrate hydrates, whose physical and chemical characteristics could meet the requirements needed for their application in buildings. Simulations with a dynamic building simulation tool are carried out to evaluate the performance of clathrate hydrates in enhancing thermal comfort through the moderation of summer temperature swings and, therefore, in reducing energy consumption. Simulations suggest that clathrate hydrates have a potential in terms of improvement of indoor thermal comfort and a reduction of energy consumption for cooling. Cooling effects of 0.5 °C and reduced overheating hours of up to 1.1% are predicted.

  16. MORPHOLOGY OF METHANE HYDRATE HOST SEDIMENTS.

    Energy Technology Data Exchange (ETDEWEB)

    JONES,K.W.; FENG,H.; TOMOV,S.; WINTER,W.J.; EATON,M.; MAHAJAN,D.

    2004-12-01

    Results from simulated experiments in several laboratories show that host sediments influence hydrate formation in accord with known heterogeneity of host sediments at sites of gas hydrate occurrence (1). For example, in Mackenzie Delta, NWT Canada (Mallik 2L-38 well), coarser-grained units (pore-filling model) are found whereas in the Gulf of Mexico, the found hydrate samples do not appear to be lithologically controlled. We have initiated a systematic study of sediments, initially focusing on samples from various depths at a specific site, to establish a correlation with hydrate occurrence (or variations thereof) to establish differences in their microstructure, porosity, and other associated properties. The synchrotron computed microtomography (CMT) set-up at the X-27A tomography beam line at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory was used as a tool to study sediments from Blake Ridge at three sub bottom depths of 0.2, 50, and 667 meters. Results from the tomographic analysis of the deepest sample (667 m) are presented here to illustrate how tomography can be used to obtain new insights into the structures of methane hydrate host sediments. The investigation shows the internal grain/pore space resolution in the microstructure and a 3-D visualization of the connecting pathways obtained following data segmentation into pore space and grains within the sediment sample. The analysis gives the sample porosity, specific surface area, mean particle size, and tortuosity, as well. An earlier report on the experimental program has been given by Mahajan et al. (2).

  17. China's Research on Non-conventional Energy Resources- Gas Hydrate

    Institute of Scientific and Technical Information of China (English)

    Pu Ming; Ma Jianguo

    2002-01-01

    @@ Methane exists in ice-like formations called gas hydrate. Hydrate traps methane molecules inside a cage of frozen water. The magnitude of this previously unknown global storehouse of methane is truly staggering and has raised serious inquiry into the possibility of using methane hydrate as a substitute source of energy for oil and conventional natural gas. According to the estimation by PGC, gas hydrate deposits amount to 7.6 × 1018m3 and contain more than twice as much organic carbon as all the world's coal, oil and non-hydrate natural gas combined.

  18. Indian National Gas Hydrate Program Expedition 01 report

    Science.gov (United States)

    Collett, Timothy S.; Riedel, M.; Boswell, R.; Presley, J.; Kumar, P.; Sathe, A.; Sethi, A.; Lall, M.; ,

    2015-01-01

    Gas hydrate is a naturally occurring “ice-like” combination of natural gas and water that has the potential to serve as an immense resource of natural gas from the world’s oceans and polar regions. However, gas-hydrate recovery is both a scientific and a technical challenge and much remains to be learned about the geologic, engineering, and economic factors controlling the ultimate energy resource potential of gas hydrate. The amount of natural gas contained in the world’s gas-hydrate accumulations is enormous, but these estimates are speculative and range over three orders of magnitude from about 2,800 to 8,000,000 trillion cubic meters of gas. By comparison, conventional natural gas accumulations (reserves and undiscovered, technically recoverable resources) for the world are estimated at approximately 440 trillion cubic meters. Gas recovery from gas hydrate is hindered because the gas is in a solid form and because gas hydrate commonly occurs in remote Arctic and deep marine environments. Proposed methods of gas recovery from gas hydrate generally deal with disassociating or “melting” in situ gas hydrate by heating the reservoir beyond the temperature of gas-hydrate formation, or decreasing the reservoir pressure below hydrate equilibrium. The pace of energy-related gas hydrate assessment projects has accelerated over the past several years.

  19. Solid state interconversion between anhydrous norfloxacin and its hydrates.

    Science.gov (United States)

    Chongcharoen, Wanchai; Byrn, Stephen R; Sutanthavibul, Narueporn

    2008-01-01

    This work is focused on characterizing and evaluating the solid state interconversion of norfloxacin (NF) hydrates. Four stoichiometric NF hydrates, dihydrate, hemipentahydrate, trihydrate, pentahydrate and a disordered NF state, were generated by various methods and characterized by X-ray powder diffractometry (XRPD), thermal analysis and Karl Fisher titrimetry. XRPD patterns of all NF hydrates exhibited crystalline structures. NF hydrate conversion was studied with respect to mild elevated temperature and various degrees of moisture levels. NF hydrates transformed to anhydrous NF Form A after gentle heating at 60 degrees C for 48 h except dihydrate and trihydrate where mixture in XRPD patterns between anhydrous NF Form A and former structures existed. Desiccation of NF hydrates at 0% RH for 7 days resulted in only partial removal of water molecules from the hydrated structures. The hydrated transitional phase and the disordered NF state were obtained from the incomplete dehydration of NF hydrates after thermal treatment and pentahydrate NF after desiccation, respectively. Anhydrous NF Form A and NF hydrates transformed to pentahydrate NF when exposed to high moisture environment except dihydrate. In conclusion, surrounding moisture levels, temperatures and the duration of exposure strongly influenced the interconversion pathways and stoichiometry of anhydrous NF and its hydrates. (c) 2007 Wiley-Liss, Inc.

  20. Characterization of un-hydrated and hydrated BioAggregate™ and MTA Angelus™.

    Science.gov (United States)

    Camilleri, J; Sorrentino, F; Damidot, D

    2015-04-01

    BioAggregate™ is a novel material introduced for use as a root-end filling material. It is tricalcium silicate-based, free of aluminium and uses tantalum oxide as radiopacifier. BioAggregate contains additives to enhance the material performance. The purpose of this research was to characterize the un-hydrated and hydrated forms of BioAggregate using a combination of techniques, verify whether the additives if present affect the properties of the set material and compare these properties to those of MTA Angelus™. Un-hydrated and hydrated BioAggregate and MTA Angelus were assessed. Un-hydrated cement was tested for chemical composition, specific surface area, mineralogy and kinetics of hydration. The set material was investigated for mineralogy, microstructure and bioactivity. Scanning electron microscopy, X-ray energy dispersive spectroscopic analysis, X-ray fluorescence spectroscopy, X-ray diffraction and isothermal calorimetry were employed. The specific surface area was investigated using a gas adsorption method with nitrogen as the probe. BioAggregate was composed of tricalcium silicate, tantalum oxide, calcium phosphate and silicon dioxide and was free of aluminium. On hydration, the tricalcium silicate produced calcium silicate hydrate and calcium hydroxide. The former was deposited around the cement grains, while the latter reacted with the silicon dioxide to form additional calcium silicate hydrate. This resulted in reduction of calcium hydroxide in the aged cement. MTA Angelus reacted in a similar fashion; however, since it contained no additives, the calcium hydroxide was still present in the aged cement. Bioactivity was demonstrated by deposition of hydroxyapatite. BioAggregate exhibited a high specific surface area. Nevertheless, the reactivity determined by isothermal calorimetry appeared to be slow compared to MTA Angelus. The tantalum oxide as opposed to bismuth oxide was inert, and tantalum was not leached in solution. BioAggregate exhibited

  1. Natural Gas Evolution in a Gas Hydrate Melt: Effect of Thermodynamic Hydrate Inhibitors.

    Science.gov (United States)

    Sujith, K S; Ramachandran, C N

    2017-01-12

    Natural gas extraction from gas hydrate sediments by injection of hydrate inhibitors involves the decomposition of hydrates. The evolution of dissolved gas from the hydrate melt is an important step in the extraction process. Using classical molecular dynamics simulations, we study the evolution of dissolved methane from its hydrate melt in the presence of two thermodynamic hydrate inhibitors, NaCl and CH3OH. An increase in the concentration of hydrate inhibitors is found to promote the nucleation of methane nanobubbles in the hydrate melt. Whereas NaCl promotes bubble formation by enhancing the hydrophobic interaction between aqueous CH4 molecules, CH3OH molecules assist bubble formation by stabilizing CH4 bubble nuclei formed in the solution. The CH3OH molecules accumulate around the nuclei leading to a decrease in the surface tension at their interface with water. The nanobubbles formed are found to be highly dynamic with frequent exchange of CH4 molecules between the bubble and the surrounding liquid. A quantitative analysis of the dynamic behavior of the bubble is performed by introducing a unit step function whose value depends on the location of CH4 molecules with respect to the bubble. It is observed that an increase in the concentration of thermodynamic hydrate inhibitors reduces the exchange process, making the bubble less dynamic. It is also found that for a given concentration of the inhibitor, larger bubbles are less dynamic compared to smaller ones. The dependence of the dynamic nature of nanobubbles on bubble size and inhibitor concentration is correlated with the solubility of CH4 and the Laplace pressure within the bubble. The effect of CO2 on the formation of nanobubble in the CH4-CO2 mixed gas hydrate melt in the presence of inhibitors is also examined. The simulations show that the presence of CO2 molecules significantly reduces the induction time for methane nanobubble nucleation. The role of CO2 in the early nucleation of bubble is explained

  2. Towards a green hydrate inhibitor: imaging antifreeze proteins on clathrates.

    Directory of Open Access Journals (Sweden)

    Raimond Gordienko

    Full Text Available The formation of hydrate plugs in oil and gas pipelines is a serious industrial problem and recently there has been an increased interest in the use of alternative hydrate inhibitors as substitutes for thermodynamic inhibitors like methanol. We show here that antifreeze proteins (AFPs possess the ability to modify structure II (sII tetrahydrofuran (THF hydrate crystal morphologies by adhering to the hydrate surface and inhibiting growth in a similar fashion to the kinetic inhibitor poly-N-vinylpyrrolidone (PVP. The effects of AFPs on the formation and growth rate of high-pressure sII gas mix hydrate demonstrated that AFPs are superior hydrate inhibitors compared to PVP. These results indicate that AFPs may be suitable for the study of new inhibitor systems and represent an important step towards the development of biologically-based hydrate inhibitors.

  3. Water retention curve for hydrate-bearing sediments

    Science.gov (United States)

    Dai, Sheng; Santamarina, J. Carlos

    2013-11-01

    water retention curve plays a central role in numerical algorithms that model hydrate dissociation in sediments. The determination of the water retention curve for hydrate-bearing sediments faces experimental difficulties, and most studies assume constant water retention curves regardless of hydrate saturation. This study employs network model simulation to investigate the water retention curve for hydrate-bearing sediments. Results show that (1) hydrate in pores shifts the curve to higher capillary pressures and the air entry pressure increases as a power function of hydrate saturation; (2) the air entry pressure is lower in sediments with patchy rather than distributed hydrate, with higher pore size variation and pore connectivity or with lower specimen slenderness along the flow direction; and (3) smaller specimens render higher variance in computed water retention curves, especially at high water saturation Sw > 0.7. Results are relevant to other sediment pore processes such as bioclogging and mineral precipitation.

  4. A Wearable Hydration Sensor with Conformal Nanowire Electrodes.

    Science.gov (United States)

    Yao, Shanshan; Myers, Amanda; Malhotra, Abhishek; Lin, Feiyan; Bozkurt, Alper; Muth, John F; Zhu, Yong

    2017-01-27

    A wearable skin hydration sensor in the form of a capacitor is demonstrated based on skin impedance measurement. The capacitor consists of two interdigitated or parallel electrodes that are made of silver nanowires (AgNWs) in a polydimethylsiloxane (PDMS) matrix. The flexible and stretchable nature of the AgNW/PDMS electrode allows conformal contact to the skin. The hydration sensor is insensitive to the external humidity change and is calibrated against a commercial skin hydration system on an artificial skin over a wide hydration range. The hydration sensor is packaged into a flexible wristband, together with a network analyzer chip, a button cell battery, and an ultralow power microprocessor with Bluetooth. In addition, a chest patch consisting of a strain sensor, three electrocardiography electrodes, and a skin hydration sensor is developed for multimodal sensing. The wearable wristband and chest patch may be used for low-cost, wireless, and continuous monitoring of skin hydration and other health parameters.

  5. Comparative Assessment of Advanced Gay Hydrate Production Methods

    Energy Technology Data Exchange (ETDEWEB)

    M. D. White; B. P. McGrail; S. K. Wurstner

    2009-06-30

    Displacing natural gas and petroleum with carbon dioxide is a proven technology for producing conventional geologic hydrocarbon reservoirs, and producing additional yields from abandoned or partially produced petroleum reservoirs. Extending this concept to natural gas hydrate production offers the potential to enhance gas hydrate recovery with concomitant permanent geologic sequestration. Numerical simulation was used to assess a suite of carbon dioxide injection techniques for producing gas hydrates from a variety of geologic deposit types. Secondary hydrate formation was found to inhibit contact of the injected CO{sub 2} regardless of injectate phase state, thus diminishing the exchange rate due to pore clogging and hydrate zone bypass of the injected fluids. Additional work is needed to develop methods of artificially introducing high-permeability pathways in gas hydrate zones if injection of CO{sub 2} in either gas, liquid, or micro-emulsion form is to be more effective in enhancing gas hydrate production rates.

  6. Inactivation of enteroviruses in sewage with ozone

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, O.E.; Bogdanov, M.V.; Kazantseva, V.A.; Gabrilevskaia, L.N.; Kodkind, G.K.H.

    The study of ozone inactivation of enteroviruses in sewage showed the presence in sewage of suspensions of organic origin and bacterial flora to influence the rate of inactivation. The inactivation rate of poliomyelitis virus in sewage free from organic suspension and bacterial flora was significantly higher than that in sewage containing such suspension and bacterial flora. The inactivation rate of enteroviruses was found not to depend upon the protein and salt composition and pH of sewage or strain appurtenance of viruses. The inactivation rate of enteroviruses directly depended upon the dose of ozone and time of contact with it. Differences in the resistance of different types of poliomyelitis virus, ECHO and Coxsackie viruses to the effect of ozone are likely exist. These differences are manifested within the range of relatively small doses of ozone. E. coli is more resistant to ozone than entero-viruses. The results of laboratory studies were used to choose the regimen of sanitation of urban sewage to be used in technological cycles of industrial enterprises.

  7. Genes that escape from X inactivation.

    Science.gov (United States)

    Berletch, Joel B; Yang, Fan; Xu, Jun; Carrel, Laura; Disteche, Christine M

    2011-08-01

    To achieve a balanced gene expression dosage between males (XY) and females (XX), mammals have evolved a compensatory mechanism to randomly inactivate one of the female X chromosomes. Despite this chromosome-wide silencing, a number of genes escape X inactivation: in women about 15% of X-linked genes are bi-allelically expressed and in mice, about 3%. Expression from the inactive X allele varies from a few percent of that from the active allele to near equal expression. While most genes have a stable inactivation pattern, a subset of genes exhibit tissue-specific differences in escape from X inactivation. Escape genes appear to be protected from the repressive chromatin modifications associated with X inactivation. Differences in the identity and distribution of escape genes between species and tissues suggest a role for these genes in the evolution of sex differences in specific phenotypes. The higher expression of escape genes in females than in males implies that they may have female-specific roles and may be responsible for some of the phenotypes observed in X aneuploidy.

  8. In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    Science.gov (United States)

    Lee, M.W.; Collett, T.S.

    2011-01-01

    In 2006, the U.S. Geological Survey (USGS) completed detailed analysis and interpretation of available 2-D and 3-D seismic data and proposed a viable method for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area of northern Alaska. To validate the predictions of the USGS and to acquire critical reservoir data needed to develop a long-term production testing program, a well was drilled at the Mount Elbert prospect in February, 2007. Numerous well log data and cores were acquired to estimate in-situ gas hydrate saturations and reservoir properties.Gas hydrate saturations were estimated from various well logs such as nuclear magnetic resonance (NMR), P- and S-wave velocity, and electrical resistivity logs along with pore-water salinity. Gas hydrate saturations from the NMR log agree well with those estimated from P- and S-wave velocity data. Because of the low salinity of the connate water and the low formation temperature, the resistivity of connate water is comparable to that of shale. Therefore, the effect of clay should be accounted for to accurately estimate gas hydrate saturations from the resistivity data. Two highly gas hydrate-saturated intervals are identified - an upper ???43 ft zone with an average gas hydrate saturation of 54% and a lower ???53 ft zone with an average gas hydrate saturation of 50%; both zones reach a maximum of about 75% saturation. ?? 2009.

  9. Hydration index--a better parameter for explaining small molecule hydration in inhibition of ice recrystallization.

    Science.gov (United States)

    Tam, Roger Y; Ferreira, Sandra S; Czechura, Pawel; Chaytor, Jennifer L; Ben, Robert N

    2008-12-24

    Several simple mono- and disaccharides have been assessed for their ability to inhibit ice recrystallization. Two carbohydrates were found to be effective recrystallization inhibitors. D-galactose (1) was the best monosaccharide and D-melibiose (5) was the most active disaccharide. The ability of each carbohydrate to inhibit ice growth was correlated to its respective hydration number reported in the literature. A hydration number reflects the number of tightly bound water molecules to the carbohydrate and is a function of carbohydrate stereochemistry. It was discovered that using the absolute hydration number of a carbohydrate does not allow one to accurately predict its ability to inhibit ice recrystallization. Consequently, we have defined a hydration index in which the hydration number is divided by the molar volume of the carbohydrate. This new parameter not only takes into account the number of water molecules tightly bound to a carbohydrate but also the size or volume of a particular solute and ultimately the concentration of hydrated water molecules. The hydration index of both mono- and disaccharides correlates well with experimentally measured RI activity. C-Linked derivatives of the monosaccharides appear to have RI activity comparable to that of their O-linked saccharides but a more thorough investigation is required. The relationship between carbohydrate concentration and RI activity was shown to be noncolligative and a 0.022 M solution of D-galactose (1) and C-linked galactose derivative (10) inhibited recrystallization as well as a 3% DMSO solution. The carbohydrates examined in this study did not possess any thermal hysteresis activity (selective depression of freezing point relative to melting point) or dynamic ice shaping. As such, we propose that they are inhibiting recrystallization at the interface between bulk water and the quasi liquid layer (a semiordered interface between ice and bulk water) by disrupting the preordering of water.

  10. Geologic implications of gas hydrates in the offshore of India: results of the National Gas Hydrate Program Expedition 01

    Science.gov (United States)

    Collett, Timothy S.; Boswell, Ray; Cochran, J.R.; Kumar, Pushpendra; Lall, Malcolm; Mazumdar, Aninda; Ramana, Mangipudi Venkata; Ramprasad, Tammisetti; Riedel, Michael; Sain, Kalachand; Sathe, Arun Vasant; Vishwanath, Krishna

    2014-01-01

    The Indian National Gas Hydrate Program Expedition 01 (NGHP-01) is designed to study the occurrence of gas hydrate along the passive continental margin of the Indian Peninsula and in the Andaman convergent margin, with special emphasis on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these two diverse settings. The NGHP-01 expedition established the presence of gas hydrates in the Krishna-Godavari and Mahanadi Basins, and the Andaman Sea. The expedition discovered in the Krishna-Godavari Basin one of the thickest gas hydrate accumulations ever documented, in the Andaman Sea one of the thickest and deepest gas hydrate stability zones in the world, and established the existence of a fully developed gas hydrate petroleum system in all three basins.

  11. Origin and character of gaseous hydrocarbons in the hydrate and non-hydrate charged sediments on the Norway - Svalbard margins

    Energy Technology Data Exchange (ETDEWEB)

    Vaular, Espen Nesheim

    2011-05-15

    Gas incubated in clathrate water-structures, stabilizes the hydrogen bonded substance termed gas hydrate. In the marine environment vast amount of carbon is stored as gas hydrates within the temperature and pressure zone these ice-like structures are stable. Natural gas hydrate mapping and characterization is important basic research that brings about critical knowledge concerning various topics. Natural gas hydrates is a vital part of the carbon cycle, it is a potential energy resource (and thereby a potential climate agent) and it is a potential geo-hazard. One of the goals the GANS initiative aimed at exploring, was the hydrate bearing sediment of the Norway -Svalbard margins, to investigate the character and expansion of natural gas hydrates. Part of the investigation was to define how the gas in the hydrated sediment was produced and where it came from. As a result this thesis addresses the matter of light hydrocarbon characterization and origin in two Norwegian hydrate deposits. On cruises to Vestnesa on the Svalbard margin and to Nyegga in the mid-Norwegian margin, samples of hydrate charged and non-hydrate charged sediments were obtained and analyzed. Through compositional and isotopic analyses the origin of the hydrate bound gas in the fluid escape feature G11 at Nyegga was determined. The hydrate incubated methane is microbial produced as well as parts of the hydrate bound ethane. The compositional analysis in both the Nyegga area and at the Vestnesa Ridge points at thermogenic contributions in the sediment interstitials and pore water. The two hydrate bearing margins show large differences in hydrocarbon content and microbial activity in the pockmarks investigated. The gravity cores from the penetrated pockmark at Vestnesa showed low hydrocarbon content and thus suggest ceased or periodic venting. The fluid flow escape features at Nyegga show large variety of flux rates based on ROV monitoring and headspace analysis of the sediment and pore water. The

  12. A statistical mechanical description of biomolecular hydration

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    We present an efficient and accurate theoretical description of the structural hydration of biological macromolecules. The hydration of molecules of almost arbitrary size (tRNA, antibody-antigen complexes, photosynthetic reaction centre) can be studied in solution and in the crystal environment. The biomolecular structure obtained from x-ray crystallography, NMR, or modeling is required as input information. The structural arrangement of water molecules near a biomolecular surface is represented by the local water density analogous to the corresponding electron density in an x-ray diffraction experiment. The water-density distribution is approximated in terms of two- and three-particle correlation functions of solute atoms with water using a potentials-of-mean-force expansion.

  13. Experimental techniques for cement hydration studies

    Directory of Open Access Journals (Sweden)

    Andreas Luttge

    2011-10-01

    Full Text Available Cement hydration kinetics is a complex problem of dissolution, nucleation and growth that is still not well understood, particularly in a quantitative way. While cement systems are unique in certain aspects they are also comparable to natural mineral systems. Therefore, geochemistry and particularly the study of mineral dissolution and growth may be able to provide insight and methods that can be utilized in cement hydration research. Here, we review mainly what is not known or what is currently used and applied in a problematic way. Examples are the typical Avrami approach, the application of Transition State Theory (TST to overall reaction kinetics and the problem of reactive surface area. Finally, we suggest an integrated approach that combines vertical scanning interferometry (VSI with other sophisticated analytical techniques such as atomic force microscopy (AFM and theoretical model calculations based on a stochastic treatment.

  14. Predicting hydration energies for multivalent ions

    DEFF Research Database (Denmark)

    Andersson, Martin Peter; Stipp, Susan Louise Svane

    2014-01-01

    (TZVP) level. Agreement with experimental data for monovalent and divalent ions is good and shows no significant systematic errors. Predictions are noticeably better than with standard COSMO. The agreement with experimental data for trivalent and tetravalent ions is slightly worse and shows systematic...... errors. Our results indicate that quantum chemical calculations combined with COSMO-RS solvent treatment is a reliable method for treating multivalent ions in solution, provided one hydration shell of explicit water molecules is included for metal cations. The accuracy is not high enough to allow...... absolute predictions of hydration energies but could be used to investigate trends for several ions, thanks to the low computational cost, in particular for ligand exchange reactions....

  15. Obsidian hydration dating of volcanic events

    Science.gov (United States)

    Friedman, I.; Obradovich, J.

    1981-01-01

    Obsidian hydration dating of volcanic events had been compared with ages of the same events determined by the 14C and KAr methods at several localities. The localities, ranging in age from 1200 to over 1 million yr, include Newberry Craters, Oregon; Coso Hot Springs, California; Salton Sea, California; Yellowstone National Park, Wyoming; and Mineral Range, Utah. In most cases the agreement is quite good. A number of factors including volcanic glass composition and exposuretemperature history must be known in order to relate hydration thickness to age. The effect of composition can be determined from chemical analysis or the refractive index of the glass. Exposure-temperature history requires a number of considerations enumerated in this paper. ?? 1981.

  16. Methane hydrates and contemporary climate change

    Science.gov (United States)

    Ruppel, Carolyn D.

    2011-01-01

    As the evidence for warming climate became better established in the latter part of the 20th century (IPCC 2001), some scientists raised the alarm that large quantities of methane (CH4) might be liberated by widespread destabilization of climate-sensitive gas hydrate deposits trapped in marine and permafrost-associated sediments (Bohannon 2008, Krey et al. 2009, Mascarelli 2009). Even if only a fraction of the liberated CH4 were to reach the atmosphere, the potency of CH4 as a greenhouse gas (GHG) and the persistence of its oxidative product (CO2) heightened concerns that gas hydrate dissociation could represent a slow tipping point (Archer et al. 2009) for Earth's contemporary period of climate change.

  17. Advances in understanding hydration of Portland cement

    Energy Technology Data Exchange (ETDEWEB)

    Scrivener, Karen L., E-mail: Karen.scrivener@epfl.ch [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 (Switzerland); Juilland, Patrick [Sika Technology AG, Zürich (Switzerland); Monteiro, Paulo J.M. [Department of Civil and Environmental Engineering, University of California at Berkeley (United States)

    2015-12-15

    Progress in understanding hydration is summarized. Evidence supports the geochemistry dissolution theory as an explanation for the induction period, in preference to the inhibiting layer theory. The growth of C–S–H is the principal factor controlling the main heat evolution peak. Electron microscopy indicates that C–S–H “needles” grow from the surface of grains. At the peak, the surface is covered, but deceleration cannot be attributed to diffusion control. The shoulder peak comes from renewed reaction of C{sub 3}A after depletion of sulfate in solution, but release of sulfate absorbed on C–S–H means that ettringite continues to form. After several days space becomes the major factor controlling hydration. The use of new analytical technique is improving our knowledge of the action of superplasticizers and leading to the design of molecules for different applications. Atomistic modeling is becoming a topic of increasing interest. Recent publications in this area are reviewed.

  18. Propane hydrate nucleation: Experimental investigation and correlation

    DEFF Research Database (Denmark)

    Jensen, Lars; Thomsen, Kaj; von Solms, Nicolas

    2008-01-01

    In this work the nucleation kinetics of propane gas hydrate has been investigated experimentally using a stirred batch reactor. The experiments have been performed isothermally recording the pressure as a function of time. Experiments were conducted at different stirring rates, but in the same......) to the aqueous phase was found to reduce the gas dissolution rate slightly. However the induction times were prolonged quite substantially upon addition of PVP.The induction time data were correlated using a newly developed induction time model based on crystallization theory also capable of taking into account...... the presence of additives. In most cases reasonable agreement between the data and the model could be obtained. The results revealed that especially the effective surface energy between propane hydrate and water is likely to change when the stirring rate varies from very high to low. The prolongation...

  19. A Proposed Unified Theory of Hydrated Asteroids

    Science.gov (United States)

    Rivkin, Andrew S.

    2016-10-01

    The last decade has seen tremendous growth in the study of hydrated and hydroxylated minerals (hereafter simply called "hydrated minerals") on asteroids. Several workers have used absorptions in the 3-µm region and a correlated absorption near 0.7 µm to determine not only the presence or absence of these minerals but gain insight into the compositions of asteroid surfaces. Spectra of hundreds of asteroids have been measured and published or presented at meetings, and we are in a position to use these newer datasets to globally assess the patterns and relationships we see, as previously done by Jones et al. (1990) and Takir et al. (2012). There are several points to be addressed by any such assessment. Several different band shapes are seen in the 3-µm region, only one of which is seen in the hydrated meteorites in our collections. However, each of the main 3-µm band shapes is represented among parent bodies of collisional families. There seems to be little correlation in general between asteroid spectral class and 3-µm band shape, save for the Ch meteorites which are overwhelmingly likely to share the same band shape as the CM meteorites. Ceres has an unusual but not unique band shape, which has thus far only been found on the largest asteroids. I will present an outline scenario for the formation and evolution of hydrated asteroids, where aqueous alteration serves to lithify some objects while other objects remain unlithified and still others differentiate and suffer collisional modification. While some details will no doubt be altered to account for better or new information, this scenario is offered as a starting point for discussion.

  20. Bioimpedance in medicine: Measuring hydration influence

    Science.gov (United States)

    Hlubik, J.; Hlubik, P.; Lhotska, L.

    2010-04-01

    The aim of the paper is to present results of our ongoing research focused on the influence of body hydration on the body impedance measurements and also on the influence of the frequency used for the measurement. The question is why to measure human body composition and if these values have beneficial results. First goal of the work deals with a question of measuring human body composition. The performed measurements showed certain influence which must be verified by repeated experiments.

  1. Methane storage in dry water gas hydrates.

    Science.gov (United States)

    Wang, Weixing; Bray, Christopher L; Adams, Dave J; Cooper, Andrew I

    2008-09-03

    Dry water stores 175 v(STP)/v methane at 2.7 MPa and 273.2 K in a hydrate form which is close to the Department of Energy volumetric target for methane storage. Dry water is a silica-stabilized free-flowing powder (95% wt water), and fast methane uptakes were observed (90% saturation uptake in 160 min with no mixing) as a result of the relatively large surface-to-volume ratio of this material.

  2. Effect of Gemini-type surfactant on methane hydrate formation

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, K.E.; Park, J.M.; Kim, C.U.; Chae, H.J.; Jeong, S.Y. [Korea Research Inst. of Chemical Technology, Jang-Dong, Yuseong-Gu, Daejeon (Korea, Republic of)

    2008-07-01

    Natural gas hydrates are formed from water and natural gas molecules at particular temperatures and pressures that become ice-like inclusion compounds. Gas hydrates offer several benefits such as energy resource potential and high storage capacity of natural gas in the form of hydrates. However, the application of natural gas hydrates has been deterred by its low formation rate and low conversion ratio of water into hydrate resulting in low actual storage capacity. This paper presented an experimental study to determine the effect of adding a novel Gemini-type surfactant on methane hydrate formation. The experimental study was described with reference to the properties of prepared diols and properties of prepared disulfonates. Gemini surfactant is the family of surfactant molecules possessing more than one hydrophobic tail and hydrophilic head group. They generally have better surface-active properties than conventional surfactants of equal chain length. The paper presented the results of the study in terms of the reactions of diols with propane sultone; storage capacity of hydrate formed with and without surfactant; and methane hydrate formation with and without disulfonate. It was concluded that the methane hydrate formation was accelerated by the addition of novel anionic Gemini-type surfactants and that hydrate formation was influenced by the surfactant concentration and alkyl chain length. For a given concentration, the surfactant with the highest chain length demonstrated the highest formation rate and storage capacity. 5 refs., 3 tabs., 4 figs.

  3. Hydration process in Portland cement blended with activated coal gangue

    Institute of Scientific and Technical Information of China (English)

    Xian-ping LIU; Pei-ming WANG; Min-ju DING

    2011-01-01

    This paper deals with the hydration of a blend of Portland cement and activated coal gangue in order to determine the relationship between the degree of hydration and compressive strength development.The hydration process was investigated by various means:isothermal calorimetry,thermal analysis,non-cvaporable water measurement,and X-ray diffraction analysis.The results show that the activated coal gangue is a pozzolanic material that contributes to the hydration of the cement blend.The pozzolanic reaction occurs over a period of between 7 and 90 d,consuming portlandite and forming both crystal hydrates and ill-crystallized calcium silicate hydrates.These hydrates are similar to those found in pure Portland cement.The results show that if activated coal gangue is substituted for cement at up to 30% (w/w),it does not significantly affect the final compressive strength of the blend.A long-term compressive strength improvement can in fact be achieved by using activated coal gangue as a supplementary cementing material.The relationship between compressive strength and degree of hydration for both pure Portland cement and blended cement can be described with the same equation.However,the parameters are different since blended cement produces fewer calcium silicate hydrates than pure Portland cement at the same degree of hydration.

  4. Gas Hydrate Growth Kinetics: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Remi-Erempagamo Tariyemienyo Meindinyo

    2016-12-01

    Full Text Available Gas hydrate growth kinetics was studied at a pressure of 90 bars to investigate the effect of temperature, initial water content, stirring rate, and reactor size in stirred semi-batch autoclave reactors. The mixing energy during hydrate growth was estimated by logging the power consumed. The theoretical model by Garcia-Ochoa and Gomez for estimation of the mass transfer parameters in stirred tanks has been used to evaluate the dispersion parameters of the system. The mean bubble size, impeller power input per unit volume, and impeller Reynold’s number/tip velocity were used for analyzing observed trends from the gas hydrate growth data. The growth behavior was analyzed based on the gas consumption and the growth rate per unit initial water content. The results showed that the growth rate strongly depended on the flow pattern in the cell, the gas-liquid mass transfer characteristics, and the mixing efficiency from stirring. Scale-up effects indicate that maintaining the growth rate per unit volume of reactants upon scale-up with geometric similarity does not depend only on gas dispersion in the liquid phase but may rather be a function of the specific thermal conductance, and heat and mass transfer limitations created by the limit to the degree of the liquid phase dispersion is batched and semi-batched stirred tank reactors.

  5. Intermolecular Hydrogen Transfer in Isobutane Hydrate

    Directory of Open Access Journals (Sweden)

    Takeshi Sugahara

    2012-05-01

    Full Text Available Electron spin resonance (ESR spectra of butyl radicals induced with γ-ray irradiation in the simple isobutane (2-methylpropane hydrate (prepared with deuterated water were investigated. Isothermal annealing results of the γ-ray-irradiated isobutane hydrate reveal that the isobutyl radical in a large cage withdraws a hydrogen atom from the isobutane molecule through shared hexagonal-faces of adjacent large cages. During this “hydrogen picking” process, the isobutyl radical is apparently transformed into a tert-butyl radical, while the sum of isobutyl and tert-butyl radicals remains constant. The apparent transformation from isobutyl to tert-butyl radicals is an irreversible first-order reaction and the activation energy was estimated to be 35 ± 3 kJ/mol, which was in agreement with the activation energy (39 ± 5 kJ/mol of hydrogen picking in the γ-ray-irradiated propane hydrate with deuterated water.

  6. The interaction of climate change and methane hydrates

    Science.gov (United States)

    Ruppel, Carolyn D.; Kessler, John D.

    2017-01-01

    Gas hydrate, a frozen, naturally-occurring, and highly-concentrated form of methane, sequesters significant carbon in the global system and is stable only over a range of low-temperature and moderate-pressure conditions. Gas hydrate is widespread in the sediments of marine continental margins and permafrost areas, locations where ocean and atmospheric warming may perturb the hydrate stability field and lead to release of the sequestered methane into the overlying sediments and soils. Methane and methane-derived carbon that escape from sediments and soils and reach the atmosphere could exacerbate greenhouse warming. The synergy between warming climate and gas hydrate dissociation feeds a popular perception that global warming could drive catastrophic methane releases from the contemporary gas hydrate reservoir. Appropriate evaluation of the two sides of the climate-methane hydrate synergy requires assessing direct and indirect observational data related to gas hydrate dissociation phenomena and numerical models that track the interaction of gas hydrates/methane with the ocean and/or atmosphere. Methane hydrate is likely undergoing dissociation now on global upper continental slopes and on continental shelves that ring the Arctic Ocean. Many factors—the depth of the gas hydrates in sediments, strong sediment and water column sinks, and the inability of bubbles emitted at the seafloor to deliver methane to the sea-air interface in most cases—mitigate the impact of gas hydrate dissociation on atmospheric greenhouse gas concentrations though. There is no conclusive proof that hydrate-derived methane is reaching the atmosphere now, but more observational data and improved numerical models will better characterize the climate-hydrate synergy in the future.

  7. Inactivation of Bacillus atrophaeus by OH radicals

    Science.gov (United States)

    Ono, Ryo; Yonetamari, Kenta; Tokumitsu, Yusuke; Yonemori, Seiya; Yasuda, Hachiro; Mizuno, Akira

    2016-08-01

    The inactivation of Bacillus atrophaeus by OH radicals is measured. This study aims to evaluate the bactericidal effects of OH radicals produced by atmospheric-pressure nonthermal plasma widely used for plasma medicine; however, in this study, OH radicals are produced by vacuum ultraviolet (VUV) photolysis of water vapor instead of plasma to allow the production of OH radicals with almost no other reactive species. A 172 nm VUV light from a Xe2 excimer lamp irradiates a He-H2O mixture flowing in a quartz tube to photodissociate H2O to produce OH, H, O, HO2, H2O2, and O3. The produced reactive oxygen species (ROS) flow out of the quartz tube nozzle to the bacteria on an agar plate and cause inactivation. The inactivation by OH radicals among the six ROS is observed by properly setting the experimental conditions with the help of simulations calculating the ROS densities. A 30 s treatment with approximately 0.1 ppm OH radicals causes visible inactivation.

  8. Pulsed electric field inactivation in a microreactor

    NARCIS (Netherlands)

    Fox, M.B.

    2006-01-01

    Pulsed electric fields (PEF) is a novel, non-thermal pasteurization method which uses short, high electric field pulses to inactivate microorganisms. The advantage of a pasteurization method like PEF compared to regular heat pasteurization is that the taste, flavour, texture and nutritional value ar

  9. Inactivation of Effector Caspases through Nondegradative Polyubiquitylation

    DEFF Research Database (Denmark)

    Ditzel, Mark; Broemer, Meike; Tenev, Tencho;

    2008-01-01

    Ubiquitin-mediated inactivation of caspases has long been postulated to contribute to the regulation of apoptosis. However, detailed mechanisms and functional consequences of caspase ubiquitylation have not been demonstrated. Here we show that the Drosophila Inhibitor of Apoptosis 1, DIAP1, block...

  10. Inactivation of prion infectivity by ionizing rays

    Science.gov (United States)

    Gominet, M.; Vadrot, C.; Austruy, G.; Darbord, J. C.

    2007-11-01

    Inactivation of prion deposits on medical devices or prion contamination in pharmaceutical raw materials is considered as impossible by using gamma irradiation. Early, the guideline WHO/CDS/CSR/APH/2000 has described irradiation as an ineffective process. But, in 2003, S. Miekka et al. noted radiation inactivation of prions in a particular application to purify human albumin, shown by the physical denaturation of the infectious protein (PrP). The aim of our study was to determine the inactivation of prions with a scrapie model (strain C506M3) by irradiating standardised preparations. Results: Gamma irradiation was partially effective, showing a 4-5 log reduction on exposure to 50 kGy. A characteristic effect-dose curve was not observed (25, 50 and 100 kGy), only an increase in the incubation period of the murine disease (229 days with 25 kGy to 290 days with 100 kGy) compared with 170 days without irradiation. Since the inactivation was not a total one, the observed effect is significant. It is proposed that further work be undertaken with the model to investigate the application of gamma radiation known levels of prion contamination.

  11. Temperature Tolerance and Inactivation of Chikungunya Virus.

    Science.gov (United States)

    Huang, Yan-Jang S; Hsu, Wei-Wen; Higgs, Stephen; Vanlandingham, Dana L

    2015-11-01

    In late 2013, chikungunya virus (CHIKV) was introduced to the New World and large outbreaks occurred in the Caribbean islands causing over a million suspected and over 20,000 laboratory-confirmed cases. Serological analysis is an essential component for the diagnosis of CHIKV infection together with virus isolation and detection of viral nucleic acid. Demonstrating virus neutralizing by serum antibodies in a plaque reduction neutralization test (PRNT) is the gold standard of all serological diagnostic assays. Prior to the testing, heat inactivation of serum at 56°C for 30 min is required for the inactivation of complement activity and adventitious viruses. The presence of adventitious contaminating viruses may interfere with the results by leading to a higher number of plaques on the monolayers and subsequent false-negative results. This procedure is widely accepted for the inactivation of flaviviruses and alphaviruses. In this study, the thermostability of CHIKV was evaluated. Heat inactivation at 56°C for 30 min was demonstrated to be insufficient for the complete removal of infectious CHIKV virions present in the samples. This thermotolerance of CHIKV could compromise the accuracy of serum tests, and therefore longer treatment for greater than 120 min is recommended.

  12. Female meiotic sex chromosome inactivation in chicken

    NARCIS (Netherlands)

    S. Schoenmakers (Sam); E. Wassenaar (Evelyne); J.W. Hoogerbrugge (Jos); J.S.E. Laven (Joop); J.A. Grootegoed (Anton); W.M. Baarends (Willy)

    2009-01-01

    textabstractDuring meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI) leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (Z

  13. Inactivation of prion infectivity by ionizing rays

    Energy Technology Data Exchange (ETDEWEB)

    Gominet, M. [Ionisos, ZI les Chatinieres, F01120 Dagneux (France); Vadrot, C.; Austruy, G. [Paris V University, Central Pharmacy of Hospitals, 4 avenue de l' Observatoire, F-75006, Paris (France); Darbord, J.C. [Paris V University, Central Pharmacy of Hospitals, 4 avenue de l' Observatoire, F-75006, Paris (France)], E-mail: darbord@pharmacie.univ-paris5.fr

    2007-11-15

    Inactivation of prion deposits on medical devices or prion contamination in pharmaceutical raw materials is considered as impossible by using gamma irradiation. Early, the guideline WHO/CDS/CSR/APH/2000 has described irradiation as an ineffective process. But, in 2003, S. Miekka et al. noted radiation inactivation of prions in a particular application to purify human albumin, shown by the physical denaturation of the infectious protein (PrP). The aim of our study was to determine the inactivation of prions with a scrapie model (strain C506M3) by irradiating standardised preparations. Results: Gamma irradiation was partially effective, showing a 4-5 log reduction on exposure to 50 kGy. A characteristic effect-dose curve was not observed (25, 50 and 100 kGy), only an increase in the incubation period of the murine disease (229 days with 25 kGy to 290 days with 100 kGy) compared with 170 days without irradiation. Since the inactivation was not a total one, the observed effect is significant. It is proposed that further work be undertaken with the model to investigate the application of gamma radiation known levels of prion contamination.

  14. Sex chromosome inactivation in the male.

    Science.gov (United States)

    Yan, Wei; McCarrey, John R

    2009-10-01

    Mammalian females have two X chromosomes, while males have only one X plus a Y chromosome. In order to balance X-linked gene dosage between the sexes, one X chromosome undergoes inactivation during development of female embryos. This process has been termed X-chromosome inactivation (XCI). Inactivation of the single X chromosome also occurs in the male, but is transient and is confined to the late stages of first meiotic prophase during spermatogenesis. This phenomenon has been termed meiotic sex chromosome inactivation (MSCI). A substantial portion ( approximately 15-25%) of X-linked mRNA-encoding genes escapes XCI in female somatic cells. While no mRNA genes are known to escape MSCI in males, approximately 80% of X-linked miRNA genes have been shown to escape this process. Recent results have led to the proposal that the RNA interference mechanism may be involved in regulating XCI in female cells. We suggest that some MSCI-escaping miRNAs may play a similar role in regulating MSCI in male germ cells.

  15. High Pressure Inactivation of HAV within Mussels

    Science.gov (United States)

    The potential of hepatitis A virus (HAV) to be inactivated within Mediterranean mussels (Mytilus galloprovincialis) and blue mussels (Mytilus edulis) by high pressure processing was evaluated. HAV was bioaccumulated within mussels to approximately 6-log10 PFU by exposure of mussels to HAV-contamina...

  16. Radiation-induced inactivation of enzymes - Molecular mechanism based on inactivation of dehydrogenases

    Science.gov (United States)

    Rodacka, Aleksandra; Gerszon, Joanna; Puchala, Mieczyslaw; Bartosz, Grzegorz

    2016-11-01

    Proteins, which have enzymatic activities play a fundamental role in the cell due to participation in most of biological processes. Oxidative-induced damage of enzymes often have marked effects on cellular processes, which in consequence determine cell functioning and survival. In this review, we focused on the radiation-induced inactivation of enzymes with particular emphasis on the inactivation of dehydrogenases. For a better understanding of this issue, the efficiency of products of water radiolysis (•OH, O2•- and H2O2) in enzyme inactivation has been analysed. Reactions of reactive oxygen species (ROS) with amino acids present in the active site of enzymes appear to have the greatest impact on enzyme inactivation.

  17. Octa-coordination and the hydrated Ba2+(aq) ion

    CERN Document Server

    Chaudhari, Mangesh I; Rempe, Susan B

    2014-01-01

    The hydration structure of Ba^{2+} ion is important for understanding blocking mechanisms in potassium ion channels. Here, we combine statistical mechanical theory, ab initio molecular dynamics simulations, and electronic structure methods to calculate the hydration free energy and local hydration structure of Ba^{2+}(aq). The predicted hydration free energy (-302.9$\\pm$0.7 kcal/mol) matches the experimental value (-302.56 kcal/mol) when the fully occupied and exclusive inner solvation shell is treated. In the local environment defined by the inner and first shell of hydrating waters, Ba^{2+} is directly coordinated by eight (8) waters. Octa-coordination resembles the structure of Ba^{2+} and K^+ bound in potassium ion channels, but differs from the local hydration structure of K^+(aq) determined earlier.

  18. Focus on the Development of Natural Gas Hydrate in China

    Directory of Open Access Journals (Sweden)

    Zhongfu Tan

    2016-05-01

    Full Text Available Natural gas hydrate, also known as combustible ice, and mainly composed of methane, is identified as a potential clean energy for the 21st century. Due to its large reserves, gas hydrate can ease problems caused by energy resource shortage and has gained attention around the world. In this paper, we focus on the exploration and development of gas hydrate as well as discussing its status and future development trend in China and abroad. We then analyze its opportunities and challenges in China from four aspects, resource, technology, economy and policy, with five forces model and Politics Economics Society Technology method. The results show China has abundance gas hydrate resource; however, backward technologies and inadequate investment have seriously hindered the future development of gas hydrate; thus, China should establish relevant cooperation framework and intuitional arrangement to attract more investment as well as breaking through technical difficulties to commercialization gas hydrate as soon as possible.

  19. Methane Production and Carbon Capture by Hydrate Swapping

    DEFF Research Database (Denmark)

    Mu, Liang; von Solms, Nicolas

    2016-01-01

    gas molecules in the structural lattice. In this work, we quantitatively investigate the swapping behavior from injection of pure carbon dioxide and the (CO2 + N2) binary gas mixture through artificial hydrate-bearing sandstone samples by use of a core-flooding experimental apparatus. A total of 13...... of pure carbon dioxide in swapping methane from its hydrate phase; the methane recovery efficiency in brine water systems is enhanced relative to pure water systems. The replenishment of a fresh (CO2 + N2) gas mixture into the vapor phase can be considered as an efficient extraction method because 46...... in small hydrate cages, as long as the equilibrium formation pressure of (CO2 + N2) binary gas hydrate is below that of methane hydrate, even though adding nitrogen to carbon dioxide reduces the thermodynamic driving force for the formation of a new hydrate. When other conditions are similar, the methane...

  20. [Raman spectroscopic investigation of hydrogen storage in nitrogen gas hydrates].

    Science.gov (United States)

    Meng, Qing-guo; Liu, Chang-ling; Ye, Yu-guang; Li, Cheng-feng

    2012-08-01

    Recently, hydrogen storage using clathrate hydrate as a medium has become a hotspot of hydrogen storage research In the present paper, the laser Raman spectroscopy was used to study the hydrogen storage in nitrogen hydrate. The synthetic nitrogen hydrate was reacted with hydrogen gas under relatively mild conditions (e.g., 15 MPa, -18 degrees C). The Raman spectra of the reaction products show that the hydrogen molecules have enclathrated the cavities of the nitrogen hydrate, with multiple hydrogen cage occupancies in the clathrate cavities. The reaction time is an important factor affecting the hydrogen storage in nitrogen hydrate. The experimental results suggest that nitrogen hydrates are expected to be an effective media for hydrogen storage.

  1. Development of Alaskan gas hydrate resources. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, V.A.; Sharma, G.D.; Patil, S.L.

    1991-06-01

    The research undertaken in this project pertains to study of various techniques for production of natural gas from Alaskan gas hydrates such as, depressurization, injection of hot water, steam, brine, methanol and ethylene glycol solutions through experimental investigation of decomposition characteristics of hydrate cores. An experimental study has been conducted to measure the effective gas permeability changes as hydrates form in the sandpack and the results have been used to determine the reduction in the effective gas permeability of the sandpack as a function of hydrate saturation. A user friendly, interactive, menu-driven, numerical difference simulator has been developed to model the dissociation of natural gas hydrates in porous media with variable thermal properties. A numerical, finite element simulator has been developed to model the dissociation of hydrates during hot water injection process.

  2. STUDY FOR NATURAL GAS HYDRATE CONVERSED FROM ICE

    Institute of Scientific and Technical Information of China (English)

    WANG Shengjie; SHEN Jiandong; HAO Miaoli; LIU Furong

    2003-01-01

    Natural gas hydrates are crystalline clathrate compounds composed of water and gases of small molecular diameters that can be used for storage and transport of natural gas as a novel method. In the paper a series of experiments of aspects and kinetics for hydrate formed from natural gas and ice were carried out on the industrial small scale production apparatus. The experimental results show that formation conditions of hydrate conversed from ice are independent of induction time, and bigger degrees of supersaturation and supercooling improved the driving force and advanced the hydrate formation.Superpressure is also favorable for ice particle conversion to hydrate. In addition, it was found there have an optimal reaction time during hydrate formation.

  3. Dielectric dispersion and protonic conduction in hydrated purple membrane.

    Science.gov (United States)

    Kovács, I; Váró, G

    1988-01-01

    Dielectric dispersion effects were studied in purple membranes of different hydration levels. The capacitance and conductivity were measured over the frequency range of 10(2) Hz to 10(5) Hz. With increase in the hydration level, the conductivity increases sharply above the critical hydration of hc = 0.06 g H2O/g protein. This critical hydration is close to the extent of the first continuous strongly bound water layer and is interpreted as the threshold for percolative proton transfer. The capacitance increases continuously with increasing hydration and a larger increase above the water content of 0.1 g H2O/g protein can be seen only at low frequencies. Maxwell-Wagner relaxation also appears above this hydration, showing the presence of a bulk water phase.

  4. Pore capillary pressure and saturation of methane hydrate bearing sediments

    Institute of Scientific and Technical Information of China (English)

    SUN Shicai; LIU Changling; YE Yuguang; LIU Yufeng

    2014-01-01

    To better understand the relationship between the pore capillary pressure and hydrate saturation in sedi-ments, a new method was proposed. First, the phase equilibria of methane hydrate in fine-grained silica sands were measured. As to the equilibrium data, the pore capillary pressure and saturation of methane hydrate were calculated. The results showed that the phase equilibria of methane hydrates in fine-grained silica sands changed due to the depressed activity of pore water caused by the surface group and negatively charged characteristic of silica particles as well as the capillary pressure in small pores together. The capil-lary pressure increased with the increase of methane hydrate saturation due to the decrease of the available pore space. However, the capillary-saturation relationship could not yet be described quantitatively because of the stochastic habit of hydrate growth.

  5. Simulation of Na channel inactivation by thiazine dyes

    OpenAIRE

    1982-01-01

    Some dyes of the methylene blue family serve as artificial inactivators of the sodium channels when present inside squid axons at a concentration of approximately 0.1 mM. The dyes restore a semblance of inactivation after normal inactivation has been destroyed by pronase. In fibers that inactivate normally, the dyes hasten the decay of sodium current. Many dye-blocked channels conduct transiently on exit of the dye molecule after repolarization to the holding potential. In contrast, normally ...

  6. Cortical inactivation by cooling in small animals

    Directory of Open Access Journals (Sweden)

    Ben eCoomber

    2011-06-01

    Full Text Available Reversible inactivation of the cortex by surface cooling is a powerful method for studying the function of a particular area. Implanted cooling cryoloops have been used to study the role of individual cortical areas in auditory processing of awake-behaving cats. Cryoloops have also been used in rodents for reversible inactivation of the cortex, but recently there has been a concern that the cryoloop may also cool non-cortical structures either directly or via the perfusion of blood, cooled as it passed close to the cooling loop. In this study we have confirmed that the loop can inactivate most of the auditory cortex without causing a significant reduction in temperature of the auditory thalamus or other sub-cortical structures. We placed a cryoloop on the surface of the guinea pig cortex, cooled it to 2°C and measured thermal gradients across the neocortical surface. We found that the temperature dropped to 20-24°C among cells within a radius of about 2.5mm away from the loop. This temperature drop was sufficient to reduce activity of most cortical cells and led to the inactivation of almost the entire auditory region. When the temperature of thalamus, midbrain, and middle ear were measured directly during cortical cooling, there was a small drop in temperature (about 4°C but this was not sufficient to directly reduce neural activity. In an effort to visualise the extent of neural inactivation we measured the uptake of thallium ions following an intravenous injection. This confirmed that there was a large reduction of activity across much of the ipsilateral cortex and only a small reduction in subcortical structures.

  7. Arguments for a Comprehensive Laboratory Research Subprogram on Hydrocarbon Gas Hydrates and Hydrate-Sediment Aggregates in the 2005-2010 DOE Methane Hydrate R & D Program

    Science.gov (United States)

    Kirby, S. H.

    2005-12-01

    Field observations of natural hydrocarbon clathrate hydrates, including responses to drilling perturbations of hydrates, well logging and analysis of drill core, and field geophysics are, combined with theoretical modeling, justifiably key activities of the authorized 2005-2010 DOE Methane Hydrate Program. It is argued in this presentation that sustained fundamental laboratory research amplifies, extends and verifies results obtained from field and modeling investigations and does so in a cost-effective way. Recent developments of hydrocarbon clathrate hydrate and sediment aggregate synthesis methods, applications of in-situ optical cell, Raman, NMR, x-ray tomography and neutron diffraction techniques, and cryogenic x-ray and SEM methods re-enforce the importance of such lab investigations. Moreover, there are large data gaps for hydrocarbon-hydrate and hydrate-sediment-aggregate properties. We give three examples: 1) All natural hydrocarbon hydrates in sediment core have been altered to varying degrees by their transit, storage, depressurization, and subsequent lab investigations, as are well-log observations during drilling operations. Interpretation of drill core properties and structure and well logs are also typically not unique. Emulations of the pressure-temperature-deformation-time histories of synthetic samples offer a productive way of gaining insight into how natural samples and logging measurements may be compositionally and texturally altered during sampling and handling. 2) Rock physics models indicate that the effects of hydrates on sediment properties depend on the manner in which hydrates articulate with the sediment matrix (their conformation). Most of these models have not been verified by direct testing using hydrocarbon hydrates with conformation checked by optical cell observations or cryogenic SEM. Such tests are needed and technically feasible. 3) Modeling the effects of exchanges of heat, multiphase fluid fluxes, and deformation involve

  8. In situ investigation of Geobacillus stearothermophilus spore germination and inactivation mechanisms under moderate high pressure.

    Science.gov (United States)

    Georget, Erika; Kapoor, Shobhna; Winter, Roland; Reineke, Kai; Song, Youye; Callanan, Michael; Ananta, Edwin; Heinz, Volker; Mathys, Alexander

    2014-08-01

    Bacterial spores are a major concern for food safety due to their high resistance to conventional preservation hurdles. Innovative hurdles can trigger bacterial spore germination or inactivate them. In this work, Geobacillus stearothermophilus spore high pressure (HP) germination and inactivation mechanisms were investigated by in situ infrared spectroscopy (FT-IR) and fluorometry. G. stearothermophilus spores' inner membrane (IM) was stained with Laurdan fluorescent dye. Time-dependent FT-IR and fluorescence spectra were recorded in situ under pressure at different temperatures. The Laurdan spectrum is affected by the lipid packing and level of hydration, and provided information on the IM state through the Laurdan generalized polarization. Changes in the -CH2 and -CH3 asymmetric stretching bands, characteristic of lipids, and in the amide I' band region, characteristic of proteins' secondary structure elements, enabled evaluation of the impact of HP on endospores lipid and protein structures. These studies were complemented by ex situ analyses (plate counts and microscopy). The methods applied showed high potential to identify germination mechanisms, particularly associated to the IM. Germination up to 3 log10 was achieved at 200 MPa and 55 °C. A molecular-level understanding of these mechanisms is important for the development and validation of multi-hurdle approaches to achieve commercial sterility.

  9. The characteristics of gas hydrates occurring in natural environment

    Science.gov (United States)

    Lu, H.; Moudrakovski, I.; Udachin, K.; Enright, G.; Ratcliffe, C.; Ripmeester, J.

    2009-12-01

    In the past few years, extensive analyses have been carried out for characterizing the natural gas hydrate samples from Cascadia, offshore Vancouver Island; Mallik, Mackenzie Delta; Mount Elbert, Alaska North Slope; Nankai Trough, offshore Japan; Japan Sea and offshore India. With the results obtained, it is possible to give a general picture of the characteristics of gas hydrates occurring in natural environment. Gas hydrate can occur in sediments of various types, from sands to clay, although it is preferentially enriched in sediments of certain types, for example coarse sands and fine volcanic ash. Most of the gas hydrates in sediments are invisible, occurring in the pores of the sediments, while some hydrates are visible, appearing as massive, nodular, planar, vein-like forms and occurring around the seafloor, in the fractures related to fault systems, or any other large spaces available in sediments. Although methane is the main component of most of the natural gas hydrates, C2 to C7 hydrocarbons have been recognized in hydrates, sometimes even in significant amounts. Shallow marine gas hydrates have been found generally to contain minor amounts of hydrogen sulfide. Gas hydrate samples with complex gas compositions have been found to have heterogeneous distributions in composition, which might reflect changes in the composition of the available gas in the surrounding environment. Depending on the gas compositions, the structure type of a natural gas hydrate can be structure I, II or H. For structure I methane hydrate, the large cages are almost fully occupied by methane molecules, while the small cages are only partly occupied. Methane hydrates occurring in different environments have been identified with almost the same crystallographic parameters.

  10. New Methods for Gas Hydrate Energy and Climate Studies

    Science.gov (United States)

    Ruppel, C. D.; Pohlman, J.; Waite, W. F.; Hunt, A. G.; Stern, L. A.; Casso, M.

    2015-12-01

    Over the past few years, the USGS Gas Hydrates Project has focused on advancements designed to enhance both energy resource and climate-hydrate interaction studies. On the energy side, the USGS now manages the Pressure Core Characterization Tools (PCCTs), which includes the Instrumented Pressure Testing Chamber (IPTC) that we have long maintained. These tools, originally built at Georgia Tech, are being used to analyze hydrate-bearing sediments recovered in pressure cores during gas hydrate drilling programs (e.g., Nankai 2012; India 2015). The USGS is now modifying the PCCTs for use on high-hydrate-saturation and sand-rich sediments and hopes to catalyze third-party tool development (e.g., visualization). The IPTC is also being used for experiments on sediments hosting synthetic methane hydrate, and our scanning electron microscope has recently been enhanced with a new cryo-stage for imaging hydrates. To support climate-hydrate interaction studies, the USGS has been re-assessing the amount of methane hydrate in permafrost-associated settings at high northern latitudes and examined the links between methane carbon emissions and gas hydrate dissociation. One approach relies on the noble gas signature of methane emissions. Hydrate dissociation uniquely releases noble gases partitioned by molecular weight, providing a potential fingerprint for hydrate-sourced methane emissions. In addition, we have linked a DOC analyzer with an IRMS at Woods Hole Oceanographic Institution, allowing rapid and precise measurement of DOC and DIC concentrations and carbon isotopic signatures. The USGS has also refined methods to measure real-time sea-air flux of methane and CO2 using cavity ring-down spectroscopy measurements coupled with other data. Acquiring ~8000 km of data on the Western Arctic, US Atlantic, and Svalbard margins, we have tested the Arctic methane catastrophe hypothesis and the link between seafloor methane emissions and sea-air methane flux.

  11. Preventing Coal and Gas Outburst Using Methane Hydration

    Institute of Scientific and Technical Information of China (English)

    吴强; 何学秋

    2003-01-01

    According to the characteristics of the methane hydrate condensing and accumulating methane, authors put forward a new technique thought way to prevent the accident of coal and gas outburst by urging the methane in the coal seams to form hydrate. The paper analyzes the feasibility of forming the methane hydrate in the coal seam from the several sides, such as, temperature,pressure, and gas components, and the primary trial results indicate the problems should be settled before the industrialization appliance realized.

  12. Effects of salinity on methane gas hydrate system

    Institute of Scientific and Technical Information of China (English)

    YANG; DingHui; XU; WenYue

    2007-01-01

    Using an approximately analytical formation,we extend the steady state model of the pure methane hydrate system to include the salinity based on the dynamic model of the methane hydrate system.The top and bottom boundaries of the methane hydrate stability zone (MHSZ) and the actual methane hydrate zone (MHZ),and the top of free gas occurrence are determined by using numerical methods and the new steady state model developed in this paper.Numerical results show that the MHZ thickness becomes thinner with increasing the salinity,and the stability is lowered and the base of the MHSZ is shifted toward the seafloor in the presence of salts.As a result,the thickness of actual hydrate occurrence becomes thinner compared with that of the pure water case.On the other hand,since lower solubility reduces the amount of gas needed to form methane hydrate,the existence of salts in seawater can actually promote methane gas hydrate formation in the hydrate stability zone.Numerical modeling also demonstrates that for the salt-water case the presence of methane within the field of methane hydrate stability is not sufficient to ensure the occurrence of gas hydrate,which can only form when the methane concentration dissolved in solution with salts exceeds the local methane solubility in salt water and if the methane flux exceeds a critical value corresponding to the rate of diffusive methane transport.In order to maintain gas hydrate or to form methane gas hydrate in marine sediments,a persistent supplied methane probably from biogenic or thermogenic processes,is required to overcome losses due to diffusion and advection.

  13. Hydration behaviour of synthetic saponite at variable relative humidity

    Indian Academy of Sciences (India)

    Karmous Mohamed Salah; Jean Louis Robert

    2011-10-01

    Hydration behaviour of synthetic saponite was examined by X-ray powder diffraction simulation at various relative humidities (RH). The basal spacing of the Ca-saponite increased stepwise with increase in RH. The (00) reflections observed reflect single or dual hydration states of smectite. Quasi-rational, intermediate, or asymmetrical reflections were observed for all XRD patterns and reflecting heterogeneity of the samples, especially along the transition between two hydration states.

  14. Obsidian hydration profiles measured by sputter-induced optical emission.

    Science.gov (United States)

    Tsong, I S; Houser, C A; Yusef, N A; Messier, R F; White, W B; Michels, J W

    1978-07-28

    The variation of concentrations of hydrogen, sodium, potassium, lithium, calcium, magnesium, silicon, and aluminum as a function of depth in the hydration layer of obsidian artifacts has been determined by sputter-induced optical emission. The surface hydration is accompanied by dealkalization, and there is a buildup of alkaline earths, calcium and magnesium in the outermost layers. These results have clarified the phenomena underlying the obsidian hydration dating technique.

  15. Inactivation of Escherichia coli phage by pulsed electric field treatment and analysis of inactivation mechanism

    Science.gov (United States)

    Tanino, Takanori; Yoshida, Tomoki; Sakai, Kazuki; Ohshima, Takayuki

    2013-03-01

    Inactivation of bacteriophage by pulsed electric field (PEF) treatment, one of the effective procedures for bacteria nonthermal inactivation, was studied. Model phage particles Escherichia coli bacteriophages M13mp18 and λ phage, were successfully inactivated by PEF treatment. The survival ratios of both bacteriophages decreased depending on the PEF treatment time when applied peak voltage was 5 or 7 kV, and the survival ratios after 12 min PEF treatment were 10-4 - 10-5. Electrophoresis analyses of biological molecules of inactivated λ phage detected no degradation of total protein and genomic DNA. These results suggested that the factor of phage inactivation by PEF treatment was not based on the degradation of protein or DNA, but on the destruction of phage particle structure. Sensitivity of E. coli phage to PEF treatment was compared with that of E. coli cell. Phage and MV1184 cell were treated with same condition PEF at 5 kV, respectively. After 12 min treatment, the survival ration of λ phage and MV1184 were 4.0 × 10-5 and 1.7 × 10-3, respectively. The survival ratio of phage was lower than that of MV1184. E. coli cell is more tolerant to inactivation with PEF treatment than coli phage.

  16. Mechanical properties of sand, silt, and clay containing tetrahydrofuran hydrate

    Science.gov (United States)

    Yun, T.S.; Santamarina, C.J.; Ruppel, C.

    2007-01-01

    The mechanical behavior of hydrate-bearing sediments subjected to large strains has relevance for the stability of the seafloor and submarine slopes, drilling and coring operations, and the analysis of certain small-strain properties of these sediments (for example, seismic velocities). This study reports on the results of comprehensive axial compression triaxial tests conducted at up to 1 MPa confining pressure on sand, crushed silt, precipitated silt, and clay specimens with closely controlled concentrations of synthetic hydrate. The results show that the stress-strain behavior of hydrate-bearing sediments is a complex function of particle size, confining pressure, and hydrate concentration. The mechanical properties of hydrate-bearing sediments at low hydrate concentration (probably 50% of pore space), the behavior becomes more independent of stress because the hydrates control both stiffness and strength and possibly the dilative tendency of sediments by effectively increasing interparticle coordination, cementing particles together, and filling the pore space. The cementation contribution to the shear strength of hydrate-bearing sediments decreases with increasing specific surface of soil minerals. The lower the effective confining stress, the greater the impact of hydrate formation on normalized strength.

  17. Ethylene Separation via Hydrate Formation in W/O Emulsions

    Directory of Open Access Journals (Sweden)

    Yong Pan

    2015-05-01

    Full Text Available An hybrid absorption-hydration method was adopted to recover C2H4 from C2H4/CH4 binary gas mixtures and the hydrate formation conditions of C2H4/CH4 mixtures was studied experimentally in diesel in water (w/o emulsions. Span 20 at a concentration of 1.0 wt% in the aqueous phase was added to form water in diesel emulsions before hydrate formation and then hydrate in diesel slurry was separated after hydrate formation. The influences of initial gas-liquid volume ratio (53–142, pressure (3.4–5.4 MPa, temperature (274.15–278.15 K, water cuts (10–30 vol%, and the mole fraction of C2H4 in feed gas (13.19–80.44 mol% upon the C2H4 separation efficiency were systematically investigated. The experimental results show that ethylene can be enriched in hydrate slurry phase with high separation factor (S and recovery ratio (R. Most hydrate formation finished in 20 min, after that, the hydrate formation rate became very slow. The conclusion is useful for determining the suitable operation conditions when adopting an absorption-hydration method to separate C2H4/CH4.

  18. Kinetics of hydrate formation using gas bubble suspended in water

    Institute of Scientific and Technical Information of China (English)

    马昌峰; 陈光进; 郭天民

    2002-01-01

    An innovative experimental technique, which was devised to study the effects of temperature and pressure on the rate of hydrate formation at the surface of a gas bubble suspended in a stagnant water phase, was adapted in this work. Under such conditions, the hydrate-growth process is free from dynamic mass transfer factors. The rate of hydrate formation of methane and carbon dioxide has been systematically studied. The measured hydrate-growth data were correlated by using the molar Gibbs free energy as driving force. In the course of the experiments, some interesting surface phenomena were observed.

  19. Continuous production of CO2 hydrate slurry added antifreeze proteins

    Energy Technology Data Exchange (ETDEWEB)

    Tokunaga, Y.; Ota, M.; Murakami, K. [Tokyo Metropolitan Univ., Tokyo (Japan). Dept. of Mechanical Engineering; Ferdows, M. [Dhaka Univ., Dhaka (Bangladesh). Dept. of Mathematics; Endou, H. [Technova Co. Ltd., Tokyo (Japan). Dept. of Mechanical Engineering

    2008-07-01

    Ocean storage of carbon dioxide (CO{sub 2}) hydrate is possible in deep seas where low temperature and high pressure conditions exist. However, when hydrates are produced in large quantities, they can plug pipelines. The addition of antifreeze proteins (AFPs) can prevent hydrate crystals from forming. The hydrate may then behave like a slurry which can be transported from a production place to a place of storage with minimal pressure loss. This study developed a production method for a CO{sub 2} hydrate slurry and presented the prospect of the inhibition effect for CO{sub 2} hydrate formation by adding AFPs. It revealed the shift in induction time, the formation rate and the torque of the agitator under conditions of AFPs at 0.01 mg/ml. It was concluded that compared to pure water, the induction time for hydrate production increased 244 per cent, the formation rate decreased 76 per cent and the ratio of the torque decreased 48 per cent by adding AFPs. The AFPs rendered the hydrate particles small and well dispersed. It was concluded that type 3 AFPs can effectively inhibit the production of structure s1 type hydrates. 4 refs., 6 figs.

  20. Geomechanical Performance of Hydrate-Bearing Sediment in Offshore Environments

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Holditch; Tad Patzek; Jonny Rutqvist; George Moridis; Richard Plumb

    2008-03-31

    The objective of this multi-year, multi-institutional research project was to develop the knowledge base and quantitative predictive capability for the description of geomechanical performance of hydrate-bearing sediments (hereafter referred to as HBS) in oceanic environments. The focus was on the determination of the envelope of hydrate stability under conditions typical of those related to the construction and operation of offshore platforms. We have developed a robust numerical simulator of hydrate behavior in geologic media by coupling a reservoir model with a commercial geomechanical code. We also investigated the geomechanical behavior of oceanic HBS using pore-scale models (conceptual and mathematical) of fluid flow, stress analysis, and damage propagation. The objective of the UC Berkeley work was to develop a grain-scale model of hydrate-bearing sediments. Hydrate dissociation alters the strength of HBS. In particular, transformation of hydrate clusters into gas and liquid water weakens the skeleton and, simultaneously, reduces the effective stress by increasing the pore pressure. The large-scale objective of the study is evaluation of geomechanical stability of offshore oil and gas production infrastructure. At Lawrence Berkeley National Laboratory (LBNL), we have developed the numerical model TOUGH + Hydrate + FLAC3D to evaluate how the formation and disassociation of hydrates in seafloor sediments affects seafloor stability. Several technical papers were published using results from this model. LBNL also developed laboratory equipment and methods to produce realistic laboratory samples of sediments containing gas hydrates so that mechanical properties could be measured in the laboratory. These properties are required to run TOUGH + Hydrate + FLAC3D to evaluate seafloor stability issues. At Texas A&M University we performed a detailed literature review to determine what gas hydrate formation properties had been measured and reported in the literature. We

  1. Nuclear Well Log Properties of Natural Gas Hydrate Reservoirs

    Science.gov (United States)

    Burchwell, A.; Cook, A.

    2015-12-01

    Characterizing gas hydrate in a reservoir typically involves a full suite of geophysical well logs. The most common method involves using resistivity measurements to quantify the decrease in electrically conductive water when replaced with gas hydrate. Compressional velocity measurements are also used because the gas hydrate significantly strengthens the moduli of the sediment. At many gas hydrate sites, nuclear well logs, which include the photoelectric effect, formation sigma, carbon/oxygen ratio and neutron porosity, are also collected but often not used. In fact, the nuclear response of a gas hydrate reservoir is not known. In this research we will focus on the nuclear log response in gas hydrate reservoirs at the Mallik Field at the Mackenzie Delta, Northwest Territories, Canada, and the Gas Hydrate Joint Industry Project Leg 2 sites in the northern Gulf of Mexico. Nuclear logs may add increased robustness to the investigation into the properties of gas hydrates and some types of logs may offer an opportunity to distinguish between gas hydrate and permafrost. For example, a true formation sigma log measures the thermal neutron capture cross section of a formation and pore constituents; it is especially sensitive to hydrogen and chlorine in the pore space. Chlorine has a high absorption potential, and is used to determine the amount of saline water within pore spaces. Gas hydrate offers a difference in elemental composition compared to water-saturated intervals. Thus, in permafrost areas, the carbon/oxygen ratio may vary between gas hydrate and permafrost, due to the increase of carbon in gas hydrate accumulations. At the Mallik site, we observe a hydrate-bearing sand (1085-1107 m) above a water-bearing sand (1107-1140 m), which was confirmed through core samples and mud gas analysis. We observe a decrease in the photoelectric absorption of ~0.5 barnes/e-, as well as an increase in the formation sigma readings of ~5 capture units in the water-bearing sand as

  2. Hydration of Portoguese cements, measurement and modelling of chemical shrinkage

    DEFF Research Database (Denmark)

    Maia, Lino; Geiker, Mette Rica; Figueiras, Joaquim A.

    2008-01-01

    form of the dispersion model. The development of hydration varied between the investigated cements; based on the measured data the degree of hydration after 24 h hydration at 20 C varied between 40 and 50%. This should be taken into account when comparing properties of concrete made from the different......Development of cement hydration was studied by measuring the chemical shrinkage of pastes. Five types of Portuguese Portland cement were used in cement pastes with . Chemical shrinkage was measured by gravimetry and dilatometry. In gravimeters results were recorded automatically during at least...

  3. Hydrate control for WAG injection in the Ekofisk field

    Energy Technology Data Exchange (ETDEWEB)

    Lekvam, Knut; Surguchev, Leonid M.; Ekrann, Steinar; Svartaas, Thor Martin; Kelland, Malcolm; Nilsson, Svante; Oevsthus, Jorun; Gjoevikli, Nils B.

    1997-12-31

    The report relates to a hydrate formation project for the Ekofisk field on the Norwegian continental shelf. To remove the possible hydrate formation problems during WAG (Water Alternating Gas) treatment, the following project was conducted to estimate roughly the distance from the injection well that hydrate formation can be prevented by whatever treatment is most appropriate. The first aim was to test experimentally whether selected kinetic hydrate inhibitors could be used, and in which concentrations and quantities. In addition evaluations were done to calculate the required volume of the inhibitor solutions that have to be injected to prevent mixing of uninhibited water and gas. 8 figs., 8 tabs.

  4. XPS study of thermal and electron-induced decomposition of Ni and Co acetylacetonate thin films for metal deposition

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Theodor; Warneke, Jonas; Zielasek, Volkmar, E-mail: zielasek@uni-bremen.de; Swiderek, Petra; Bäumer, Marcus [Institut für Angewandte und Physikalische Chemie, Universität Bremen, Postfach 330440, D-28334 Bremen (Germany)

    2016-07-15

    Optimizing thin metal film deposition techniques from metal-organic precursors such as atomic layer deposition, chemical vapor deposition (CVD), or electron beam-induced deposition (EBID) with the help of surface science analysis tools in ultrahigh vacuum requires a contamination-free precursor delivery technique, especially in the case of the less volatile precursors. For this purpose, the preparation of layers of undecomposed Ni(acac){sub 2} and Co(acac){sub 2} was tried via pulsed spray evaporation of a liquid solution of the precursors in ethanol into a flow of nitrogen on a CVD reactor. Solvent-free layers of intact precursor molecules were obtained when the substrate was held at a temperature of 115 °C. A qualitative comparison of thermally initiated and electron-induced precursor decomposition and metal center reduction was carried out. All deposited films were analyzed with respect to chemical composition quasi in situ by x-ray photoelectron spectroscopy. Thermally initiated decomposition yielded higher metal-to-metal oxide ratios in the deposit than the electron-induced process for which ratios of 60:40 and 20:80 were achieved for Ni and Co, resp. Compared to continuous EBID processes, all deposits showed low levels of carbon impurities of ∼10 at. %. Therefore, postdeposition irradiation of metal acetylacetonate layers by a focused electron beam and subsequent removal of intact precursor by dissolution in ethanol or by heating is proposed as electron beam lithography technique on the laboratory scale for the production of the metal nanostructures.

  5. Effects of Bacterial Inactivation Methods on Downstream Proteomic Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Andy; Merkley, Eric D.; Clowers, Brian H.; Hutchison, Janine R.; Kreuzer, Helen W.

    2015-05-01

    Inactivation of pathogenic microbial samples is often necessary for the protection of researchers and to comply with local and federal regulations. By its nature, biological inactivation causes changes to microbial samples, potentially affecting observed experimental results. While inactivation induced damage to materials such as DNA has been evaluated, the effect of various inactivation strategies on proteomic data, to our knowledge, has not been discussed. To this end, we inactivated samples of Yersinia pestis and Escherichia coli by autoclave, ethanol, or irradiation treatment to determine how inactivation changes liquid chromatography tandem mass spectrometry data quality as well as apparent protein content of cells. Proteomic datasets obtained from aliquots of samples inactivated by different methods were highly similar, with Pearson correlation coefficients ranging from 0.822 to 0.985 and 0.816 to 0.985 for E. coli and Y. pestis, respectively, suggesting that inactivation had only slight impacts on the set of proteins identified. In addition, spectral quality metrics such as distributions of various database search algorithm scores remained constant across inactivation methods, indicating that inactivation does not appreciably degrade spectral quality. Though overall changes resulting from inactivation were small, there were detectable trends. For example, one-sided Fischer exact tests determined that periplasmic proteins decrease in observed abundance after sample inactivation by autoclaving (α = 1.71x10-2 for E. coli, α = 4.97x10-4 for Y. pestis) and irradiation (α = 9.43x10-7 for E. coli, α = 1.21x10-5 for Y. pestis) when compared to controls that were not inactivated. Based on our data, if sample inactivation is necessary, we recommend inactivation with ethanol treatment with secondary preference given to irradiation.

  6. Life Origination Hydrate Hypothesis (LOH-Hypothesis

    Directory of Open Access Journals (Sweden)

    Victor Ostrovskii

    2012-01-01

    Full Text Available The paper develops the Life Origination Hydrate Hypothesis (LOH-hypothesis, according to which living-matter simplest elements (LMSEs, which are N-bases, riboses, nucleosides, nucleotides, DNA- and RNA-like molecules, amino-acids, and proto-cells repeatedly originated on the basis of thermodynamically controlled, natural, and inevitable processes governed by universal physical and chemical laws from CH4, niters, and phosphates under the Earth's surface or seabed within the crystal cavities of the honeycomb methane-hydrate structure at low temperatures; the chemical processes passed slowly through all successive chemical steps in the direction that is determined by a gradual decrease in the Gibbs free energy of reacting systems. The hypothesis formulation method is based on the thermodynamic directedness of natural movement and consists ofan attempt to mentally backtrack on the progression of nature and thus reveal principal milestones alongits route. The changes in Gibbs free energy are estimated for different steps of the living-matter origination process; special attention is paid to the processes of proto-cell formation. Just the occurrence of the gas-hydrate periodic honeycomb matrix filled with LMSEs almost completely in its final state accounts for size limitation in the DNA functional groups and the nonrandom location of N-bases in the DNA chains. The slowness of the low-temperature chemical transformations and their “thermodynamic front” guide the gross process of living matter origination and its successive steps. It is shown that the hypothesis is thermodynamically justified and testable and that many observed natural phenomena count in its favor.

  7. A realistic molecular model of cement hydrates

    OpenAIRE

    PELLENQ, Roland J.-M.; Kushima, Akihiro; Shahsavari, Rouzbeh; Van Vliet, Krystyn J.; Markus J. Buehler; Yip, Sidney; Ulm, Franz-Josef

    2009-01-01

    Despite decades of studies of calcium-silicate-hydrate (C-S-H), the structurally complex binder phase of concrete, the interplay between chemical composition and density remains essentially unexplored. Together these characteristics of C-S-H define and modulate the physical and mechanical properties of this “liquid stone” gel phase. With the recent determination of the calcium/silicon (C/S = 1.7) ratio and the density of the C-S-H particle (2.6 g/cm3) by neutron scattering measurements, there...

  8. The characteristics of gas hydrates recovered from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    Science.gov (United States)

    Lu, H.; Lorenson, T.D.; Moudrakovski, I.L.; Ripmeester, J.A.; Collett, T.S.; Hunter, R.B.; Ratcliffe, C.I.

    2011-01-01

    Systematic analyses have been carried out on two gas hydrate-bearing sediment core samples, HYPV4, which was preserved by CH4 gas pressurization, and HYLN7, which was preserved in liquid-nitrogen, recovered from the BPXA-DOE-USGS Mount Elbert Stratigraphic Test Well. Gas hydrate in the studied core samples was found by observation to have developed in sediment pores, and the distribution of hydrate saturation in the cores imply that gas hydrate had experienced stepwise dissociation before it was stabilized by either liquid nitrogen or pressurizing gas. The gas hydrates were determined to be structure Type I hydrate with hydration numbers of approximately 6.1 by instrumentation methods such as powder X-ray diffraction, Raman spectroscopy and solid state 13C NMR. The hydrate gas composition was predominantly methane, and isotopic analysis showed that the methane was of thermogenic origin (mean ??13C=-48.6??? and ??D=-248??? for sample HYLN7). Isotopic analysis of methane from sample HYPV4 revealed secondary hydrate formation from the pressurizing methane gas during storage. ?? 2010 Elsevier Ltd.

  9. Are seafloor pockmarks on the Chatham Rise, New Zealand, linked to CO2 hydrates? Gas hydrate stability considerations.

    Science.gov (United States)

    Pecher, I. A.; Davy, B. W.; Rose, P. S.; Coffin, R. B.

    2015-12-01

    Vast areas of the Chatham Rise east of New Zealand are covered by seafloor pockmarks. Pockmark occurrence appears to be bathymetrically controlled with a band of smaller pockmarks covering areas between 500 and 700 m and large seafloor depressions beneath 800 m water depth. The current depth of the top of methane gas hydrate stability in the ocean is about 500 m and thus, we had proposed that pockmark formation may be linked to methane gas hydrate dissociation during sealevel lowering. However, while seismic profiles show strong indications of fluid flow, geochemical analyses of piston cores do not show any evidence for current or past methane flux. The discovery of Dawsonite, indicative of significant CO2 flux, in a recent petroleum exploration well, together with other circumstantial evidence, has led us to propose that instead of methane hydrate, CO2 hydrate may be linked to pockmark formation. We here present results from CO2 hydrate stability calculations. Assuming water temperature profiles remain unchanged, we predict the upper limit of pockmark occurrence to coincide with the top of CO2 gas hydrate stability during glacial-stage sealevel lowstands. CO2 hydrates may therefore have dissociated during sealevel lowering leading to gas escape and pockmark formation. In contrast to our previous model linking methane hydrate dissociation to pockmark formation, gas hydrates would dissociate beneath a shallow base of CO2 hydrate stability, rather than on the seafloor following upward "grazing" of the top of methane hydrate stability. Intriguingly, at the water depths of the larger seafloor depressions, the base of gas hydrate stability delineates the phase boundary between CO2 hydrates and super-saturated CO2. We caution that because of the high solubility of CO2, dissociation from hydrate to free gas or super-saturated CO2 would imply high concentrations of CO2 and speculate that pockmark formation may be linked to CO2 hydrate dissolution rather than dissociation

  10. Electrical properties of methane hydrate + sediment mixtures: The σ of CH4 Hydrate + Sediment

    Energy Technology Data Exchange (ETDEWEB)

    Du Frane, Wyatt L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Stern, Laura A. [U. S. Geological Survey, Menlo Park, CA (United States); Constable, Steven [Scripps Institution of Oceanography, La Jolla, CA (United States); Weitemeyer, Karen A. [Scripps Institution of Oceanography, La Jolla, CA (United States); National Oceanography Centre Southampton (United Kingdom), Univ. of Southampton Waterfront Campus, Southampton (United Kingdom); Smith, Megan M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Roberts, Jeffery J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-30

    Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. We built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (σ) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EM field surveys. We report σ measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low σ but is found to increase the overall σ of mixtures with well-connected methane hydrate. Alternatively, the overall σ decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. Finally, these results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems.

  11. Well log characterization of natural gas-hydrates

    Science.gov (United States)

    Collett, Timothy S.; Lee, Myung W.

    2012-01-01

    In the last 25 years there have been significant advancements in the use of well-logging tools to acquire detailed information on the occurrence of gas hydrates in nature: whereas wireline electrical resistivity and acoustic logs were formerly used to identify gas-hydrate occurrences in wells drilled in Arctic permafrost environments, more advanced wireline and logging-while-drilling (LWD) tools are now routinely used to examine the petrophysical nature of gas-hydrate reservoirs and the distribution and concentration of gas hydrates within various complex reservoir systems. Resistivity- and acoustic-logging tools are the most widely used for estimating the gas-hydrate content (i.e., reservoir saturations) in various sediment types and geologic settings. Recent integrated sediment coring and well-log studies have confirmed that electrical-resistivity and acoustic-velocity data can yield accurate gas-hydrate saturations in sediment grain-supported (isotropic) systems such as sand reservoirs, but more advanced log-analysis models are required to characterize gas hydrate in fractured (anisotropic) reservoir systems. New well-logging tools designed to make directionally oriented acoustic and propagation-resistivity log measurements provide the data needed to analyze the acoustic and electrical anisotropic properties of both highly interbedded and fracture-dominated gas-hydrate reservoirs. Advancements in nuclear magnetic resonance (NMR) logging and wireline formation testing (WFT) also allow for the characterization of gas hydrate at the pore scale. Integrated NMR and formation testing studies from northern Canada and Alaska have yielded valuable insight into how gas hydrates are physically distributed in sediments and the occurrence and nature of pore fluids(i.e., free water along with clay- and capillary-bound water) in gas-hydrate-bearing reservoirs. Information on the distribution of gas hydrate at the pore scale has provided invaluable insight on the mechanisms

  12. Investigating the Metastability of Clathrate Hydrates for Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Carolyn Ann [Colorado School of Mines

    2014-11-18

    Important breakthrough discoveries have been achieved from the DOE award on the key processes controlling the synthesis and structure-property relations of clathrate hydrates, which are critical to the development of clathrate hydrates as energy storage materials. Key achievements include: (i) the discovery of key clathrate hydrate building blocks (stable and metastable) leading to clathrate hydrate nucleation and growth; (ii) development of a rapid clathrate hydrate synthesis route via a seeding mechanism; (iii) synthesis-structure relations of H2 + CH4/CO2 binary hydrates to control thermodynamic requirements for energy storage and sequestration applications; (iv) discovery of a new metastable phase present during clathrate hydrate structural transitions. The success of our research to-date is demonstrated by the significant papers we have published in high impact journals, including Science, Angewandte Chemie, J. Am. Chem. Soc. Intellectual Merits of Project Accomplishments: The intellectual merits of the project accomplishments are significant and transformative, in which the fundamental coupled computational and experimental program has provided new and critical understanding on the key processes controlling the nucleation, growth, and thermodynamics of clathrate hydrates containing hydrogen, methane, carbon dioxide, and other guest molecules for energy storage. Key examples of the intellectual merits of the accomplishments include: the first discovery of the nucleation pathways and dominant stable and metastable structures leading to clathrate hydrate formation; the discovery and experimental confirmation of new metastable clathrate hydrate structures; the development of new synthesis methods for controlling clathrate hydrate formation and enclathration of molecular hydrogen. Broader Impacts of Project Accomplishments: The molecular investigations performed in this project on the synthesis (nucleation & growth)-structure-stability relations of clathrate

  13. Inactivation of Microorganisms by Gamma Irradiation

    Science.gov (United States)

    2005-12-01

    L’inactivation cbimique (ex :formald6hyde) et thermique (ex :autoclave) peut atre utilis~e dans la pr6paration des antig~nes mais la structure d’antig~ne...change overtime. Due to 60Co having a half life of 5.24 years, the time required to achieve the initial central dose rate (kGy/hr) at 0.00 years from

  14. Female meiotic sex chromosome inactivation in chicken.

    Science.gov (United States)

    Schoenmakers, Sam; Wassenaar, Evelyne; Hoogerbrugge, Jos W; Laven, Joop S E; Grootegoed, J Anton; Baarends, Willy M

    2009-05-01

    During meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI) leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (ZW), whereas males have the homogametic ZZ constitution. During chicken oogenesis, the heterologous ZW pair reaches a state of complete heterologous synapsis, and this might enable maintenance of transcription of Z- and W chromosomal genes during meiotic prophase. Herein, we show that the ZW pair is transiently silenced, from early pachytene to early diplotene using immunocytochemistry and gene expression analyses. We propose that ZW inactivation is most likely achieved via spreading of heterochromatin from the W on the Z chromosome. Also, persistent meiotic DNA double-strand breaks (DSBs) may contribute to silencing of Z. Surprisingly, gammaH2AX, a marker of DSBs, and also the earliest histone modification that is associated with XY body formation in mammalian and marsupial spermatocytes, does not cover the ZW during the synapsed stage. However, when the ZW pair starts to desynapse, a second wave of gammaH2AX accumulates on the unsynapsed regions of Z, which also show a reappearance of the DSB repair protein RAD51. This indicates that repair of meiotic DSBs on the heterologous part of Z is postponed until late pachytene/diplotene, possibly to avoid recombination with regions on the heterologously synapsed W chromosome. Two days after entering diplotene, the Z looses gammaH2AX and shows reactivation. This is the first report of meiotic sex chromosome inactivation in a species with female heterogamety, providing evidence that this mechanism is not specific to spermatogenesis. It also indicates the presence of an evolutionary force that drives meiotic sex chromosome inactivation independent of the final achievement of synapsis.

  15. Inactivating CUX1 mutations promote tumorigenesis

    OpenAIRE

    2013-01-01

    A major challenge for cancer genetics is to determine which low frequency somatic mutations are drivers of tumorigenesis. Here we interrogate the genomes of 7,651 diverse human cancers to identify novel drivers and find inactivating mutations in the homeodomain transcription factor CUX1 (cut-like homeobox 1) in ~1-5% of tumors. Meta-analysis of CUX1 mutational status in 2,519 cases of myeloid malignancies reveals disruptive mutations associated with poor survival, highlighting the clinical si...

  16. Female meiotic sex chromosome inactivation in chicken.

    Directory of Open Access Journals (Sweden)

    Sam Schoenmakers

    2009-05-01

    Full Text Available During meiotic prophase in male mammals, the heterologous X and Y chromosomes remain largely unsynapsed, and meiotic sex chromosome inactivation (MSCI leads to formation of the transcriptionally silenced XY body. In birds, the heterogametic sex is female, carrying Z and W chromosomes (ZW, whereas males have the homogametic ZZ constitution. During chicken oogenesis, the heterologous ZW pair reaches a state of complete heterologous synapsis, and this might enable maintenance of transcription of Z- and W chromosomal genes during meiotic prophase. Herein, we show that the ZW pair is transiently silenced, from early pachytene to early diplotene using immunocytochemistry and gene expression analyses. We propose that ZW inactivation is most likely achieved via spreading of heterochromatin from the W on the Z chromosome. Also, persistent meiotic DNA double-strand breaks (DSBs may contribute to silencing of Z. Surprisingly, gammaH2AX, a marker of DSBs, and also the earliest histone modification that is associated with XY body formation in mammalian and marsupial spermatocytes, does not cover the ZW during the synapsed stage. However, when the ZW pair starts to desynapse, a second wave of gammaH2AX accumulates on the unsynapsed regions of Z, which also show a reappearance of the DSB repair protein RAD51. This indicates that repair of meiotic DSBs on the heterologous part of Z is postponed until late pachytene/diplotene, possibly to avoid recombination with regions on the heterologously synapsed W chromosome. Two days after entering diplotene, the Z looses gammaH2AX and shows reactivation. This is the first report of meiotic sex chromosome inactivation in a species with female heterogamety, providing evidence that this mechanism is not specific to spermatogenesis. It also indicates the presence of an evolutionary force that drives meiotic sex chromosome inactivation independent of the final achievement of synapsis.

  17. Surfactant process for promoting gas hydrate formation and application of the same

    Science.gov (United States)

    Rogers, Rudy E.; Zhong, Yu

    2002-01-01

    This invention relates to a method of storing gas using gas hydrates comprising forming gas hydrates in the presence of a water-surfactant solution that comprises water and surfactant. The addition of minor amounts of surfactant increases the gas hydrate formation rate, increases packing density of the solid hydrate mass and simplifies the formation-storage-decomposition process of gas hydrates. The minor amounts of surfactant also enhance the potential of gas hydrates for industrial storage applications.

  18. Rapid inactivation of SARS-like coronaviruses.

    Energy Technology Data Exchange (ETDEWEB)

    Kapil, Sanjay (Kansas State University, Manhattan, KS); Oberst, R. D. (Kansas State University, Manhattan, KS); Bieker, Jill Marie; Tucker, Mark David; Souza, Caroline Ann; Williams, Cecelia Victoria

    2004-03-01

    Chemical disinfection and inactivation of viruses is largely understudied, but is very important especially in the case of highly infectious viruses. The purpose of this LDRD was to determine the efficacy of the Sandia National Laboratories developed decontamination formulations against Bovine Coronavirus (BCV) as a surrogate for the coronavirus that causes Severe Acute Respiratory Syndrome (SARS) in humans. The outbreak of SARS in late 2002 resulted from a highly infectious virus that was able to survive and remain infectious for extended periods. For this study, preliminary testing with Escherichia coli MS-2 (MS-2) and Escherichia coli T4 (T4) bacteriophages was conducted to develop virucidal methodology for verifying the inactivation after treatment with the test formulations following AOAC germicidal methodologies. After the determination of various experimental parameters (i.e. exposure, concentration) of the formulations, final testing was conducted on BCV. All experiments were conducted with various organic challenges (horse serum, bovine feces, compost) for results that more accurately represent field use condition. The MS-2 and T4 were slightly more resistant than BCV and required a 2 minute exposure while BCV was completely inactivated after a 1 minute exposure. These results were also consistent for the testing conducted in the presence of the various organic challenges indicating that the test formulations are highly effective for real world application.

  19. Developmental regulation of X-chromosome inactivation.

    Science.gov (United States)

    Payer, Bernhard

    2016-08-01

    With the emergence of sex-determination by sex chromosomes, which differ in composition and number between males and females, appeared the need to equalize X-chromosomal gene dosage between the sexes. Mammals have devised the strategy of X-chromosome inactivation (XCI), in which one of the two X-chromosomes is rendered transcriptionally silent in females. In the mouse, the best-studied model organism with respect to XCI, this inactivation process occurs in different forms, imprinted and random, interspersed by periods of X-chromosome reactivation (XCR), which is needed to switch between the different modes of XCI. In this review, I describe the recent advances with respect to the developmental control of XCI and XCR and in particular their link to differentiation and pluripotency. Furthermore, I review the mechanisms, which influence the timing and choice, with which one of the two X-chromosomes is chosen for inactivation during random XCI. This has an impact on how females are mosaics with regard to which X-chromosome is active in different cells, which has implications on the severity of diseases caused by X-linked mutations.

  20. [NMF and cosmetology of cutaneous hydration].

    Science.gov (United States)

    Marty, J-P

    2002-01-01

    In the stratum corneum, the water binds to the intracellular hygroscopic and hydrosoluble substances called "natural moisturizing factors" or NMF. These "natural moisturizing factors" contained in the corneocytes are formed during epidermal differentiation and may represent up to 10 p. cent of the corneocyte mass. They are principally amino acids, carboxylic pyrrolidone acid, lactic acid, urea, glucose and mineral ions. Keratinization plays an important part in the formation of NMF that exhibit strong osmotic potential attracting the water molecules. The binding of water to NMF is the static aspect of cutaneous hydration. The second, dynamic, aspect is related to the selective permeability of the stratum corneum and to its lipid barrier properties, the permeability of which depends on the integrity and nature of the inter-corneocyte lipids and their lamellar organization between the cells. In these conditions, hydration cosmetics rely on two concepts that can be isolated or associated: the supply of hydrophilic substances to the stratum corneum, capable of attracting and retaining water (moisturizer) or capable of restoring the barrier in order to restore normal water loss or of protecting it against aggression (occlusive).

  1. Reaction of disodium cromoglycate with hydrated electrons

    Energy Technology Data Exchange (ETDEWEB)

    Carmichael, A.J.; Arroyo, C.M.; Cockerham, L.G.

    1988-01-01

    A possible mechanism by which disodium cromoglycate (DSCG) prevents a decrease in regional cerebral blood flow but not hypotension in primates following whole body gamma-irradiation was studied. Several studies have implicated superoxide radicals (O/sub 2//sup -/.) in intestinal and cerebral vascular disorders following ischemia and ionizing radiation, respectively. O/sub 2//sup -/. is formed during radiolysis in the reaction between hydrated electrons (e-aq) and dissolved oxygen. For this reason, the efficiency of DSCG to scavenge e-q and possibly prevent the formation of O/sub 2//sup -/. was studied. Hydrated electrons were produced by photolysis of potassium ferrocyanide solutions. The rate constant, k = 2.92 x 10(10) M-1s-1 for the reaction between e-aq and DSCG was determined in competition experiments using the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). This spin trap reacts rapidly with e-aq followed by protonation to yield the ESR observable DMPO-H spin adduct. The results show that DSCG is an efficient e-aq scavenger and may effectively compete with oxygen for e-aq preventing the radiolytic formation of O/sub 2//sup -/..

  2. The impact of hydrate saturation on the mechanical, electrical, and thermal properties of hydrate-bearing sand, silts, and clay

    Energy Technology Data Exchange (ETDEWEB)

    Santamarina, J.C. [Georgia Inst. of Technology, Atlanta, GA (United States). School of Civil and Environmental Engineering; Ruppel, C. [United States Geological Survey, Woods Hole, MA (United States)

    2008-07-01

    A study was conducted to provide an internally-consistent, systematically-acquired database that could help in evaluating gas hydrate reservoirs. Other objectives were to assist in geomechanical analyses, hazards evaluation and the development of methane hydrate production techniques in sandy lithologies and fine-grained sediments that exist in the northern Gulf of Mexico. An understanding of the physical properties of hydrate-bearing sediments facilitates the interpretation of geophysical field data, borehole and slope stability analyses, and reservoir simulation and production models. This paper reported on the key findings derived from 5 years of laboratory experiments conducted on synthetic samples of sand, silts, or clays subjected to various confining pressures. The samples contained controlled saturations of tetrahydrofuran hydrate formed from the dissolved phase. This internally-consistent data set was used to conduct a comprehensive analysis of the trends in geophysical and geotechnical properties as a function of hydrate saturation, soil characteristics, and other parameters. The experiments emphasized measurements of seismic velocities, electrical conductivity and permittivity, large strain deformation and strength, and thermal conductivity. The impact of hydrate formation technique on the resulting physical properties measurements were discussed. The data set was used to identify systematic effects of sediment characteristics, hydrate concentration, and state of stress. The study showed that the electrical properties of hydrate-bearing sediments are less sensitive to the method used to form hydrate in the laboratory than to hydrate saturation. It was concluded that mechanical properties are strongly influenced by both soil properties and the hydrate loci. Since the thermal conductivity depends on the interaction of several factors, it cannot be readily predicted by volume average formulations. 23 refs., 2 tabs., 9 figs.

  3. Characteristics of shallow gas hydrate in Okhotsk Sea

    Institute of Scientific and Technical Information of China (English)

    LUAN XiWu; JIN YoungKeun; Anatoly OBZHIROV; YUE BaoJing

    2008-01-01

    Multidisciplinary field investigations were carried out in Okhotsk Sea by R/V Akademik M.A. Lavrentyev (LV) of the Russian Academy of Sciences (RAS) in May 2006, supported by funding agencies from Korea, Russia, Japan and China. Geophysical data including echo-sounder, bottom profile, side-scansonar, and gravity core sample were obtained aimed to understand the characteristics and formation mechanism of shallow gas hydrates. Based on the geophysical data, we found that the methane flare detected by echo-sounder was the evidence of free gas in the sediment, while the dome structure detected by side-scan sonar and bottom profile was the root of gas venting. Gas hydrate retrieved from core on top of the dome structure which was interbedded as thin lamination or lenses with thickness varying from a few millimeters to 3 cm. Gas hydrate content in hydrate-bearing intervals visually amounted to 5%-30% of the sediment volume. This paper argued that gases in the sediment core were not all from gas hydrate decomposition during the gravity core lifting process, free gases must existed in the gas hydrate stability zone, and tectonic structure like dome structure in this paper was free gas central, gas hydrate formed only when gases over-saturated in this gas central, away from these struc tures, gas hydrate could not form due to low gas concentration.

  4. Characteristics of shallow gas hydrate in Okhotsk Sea

    Institute of Scientific and Technical Information of China (English)

    Anatoly; OBZHIROV

    2008-01-01

    Multidisciplinary field investigations were carried out in Okhotsk Sea by R/V Akademik M.A. Lavrentyev (LV) of the Russian Academy of Sciences (RAS) in May 2006, supported by funding agencies from Ko- rea, Russia, Japan and China. Geophysical data including echo-sounder, bottom profile, side-scan- sonar, and gravity core sample were obtained aimed to understand the characteristics and formation mechanism of shallow gas hydrates. Based on the geophysical data, we found that the methane flare detected by echo-sounder was the evidence of free gas in the sediment, while the dome structure de- tected by side-scan sonar and bottom profile was the root of gas venting. Gas hydrate retrieved from core on top of the dome structure which was interbedded as thin lamination or lenses with thickness varying from a few millimeters to 3 cm. Gas hydrate content in hydrate-bearing intervals visually amounted to 5%―30% of the sediment volume. This paper argued that gases in the sediment core were not all from gas hydrate decomposition during the gravity core lifting process, free gases must existed in the gas hydrate stability zone, and tectonic structure like dome structure in this paper was free gas central, gas hydrate formed only when gases over-saturated in this gas central, away from these struc- tures, gas hydrate could not form due to low gas concentration.

  5. Ultrasonic sound speed analysis of hydrating calcium sulphate hemihydrate

    NARCIS (Netherlands)

    Korte, de A.C.J.; Brouwers, H.J.H.

    2011-01-01

    This article focuses on the hydration, and associated microstructure development, of b-hemihydrate to dihydrate (gypsum). The sound velocity is used to quantify the composition of the fresh slurry as well as the hardening and hardened—porous—material. Furthermore, an overview of available hydration

  6. Putting the Deep Biosphere and Gas Hydrates on the Map

    Science.gov (United States)

    Sikorski, Janelle J.; Briggs, Brandon R.

    2016-01-01

    Microbial processes in the deep biosphere affect marine sediments, such as the formation of gas hydrate deposits. Gas hydrate deposits offer a large source of natural gas with the potential to augment energy reserves and affect climate and seafloor stability. Despite the significant interdependence between life and geology in the ocean, coverage…

  7. Spectroscopic determination of optimal hydration time of zircon surface

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez R, E. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Garcia R, G. [Instituto Tecnologico de Toluca, Division de Estudios del Posgrado, Av. Tecnologico s/n, Ex-Rancho La Virgen, 52140 Metepec, Estado de Mexico (Mexico); Garcia G, N., E-mail: eduardo.ordonez@inin.gob.m [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Av. Colon y Av. Tollocan, 50180 Toluca, Estado de Mexico (Mexico)

    2010-07-01

    When a mineral surface is immersed in an aqueous solution, it develops and electric charge produced by the amphoteric dissociation of hydroxyl groups created by the hydration of the solid surface. This is one influential surface property. The complete hydration process takes a time which is specific for each mineral species. The knowledge of the aqueous solution contact time for complete surface hydration is mandatory for further surface phenomena studies. This study deals with the optimal hydration time of the raw zircon (ZrSiO{sub 4}) surface comparing the classical potentiometric titrations with a fluorescence spectroscopy technique. The latter is easy and rea liable as it demands only one sample batch to determine the optimal time to ensure a total hydration of the zircon surface. The analytical results of neutron activation analysis showed the presence of trace quantities of Dy{sup 3+}, Eu{sup 3+} and Er{sup 3} in the bulk of zircon. The Dy{sup 3+} is structured in the zircon crystalline lattice and undergoes the same chemical reactions as zircon. Furthermore, the Dy{sup 3+} has a good fluorescent response whose intensity is enhanced by hydration molecules. The results show that, according to the potentiometric analysis, the hydration process for each batch (at least 8 sample batches) takes around 2 h, while the spectrometric method indicates only 5 minutes from only one batch. Both methods showed that the zircon surface have a 16 h optimal hydration time. (Author)

  8. The effect of stereochemistry on carbohydrate hydration in aqueous solutions

    NARCIS (Netherlands)

    Galema, Saskia Alexandra

    1992-01-01

    Although-carbohydrates are widely used, not much is known about the stereochemical aspects of hydration of carbohydrates. For D-aldohexoses, for example, there are eight different stereoisomers. Just how the hydroxy topology of a carbohydrate molecule influences the hydration behaviour in water is r

  9. Strengthening mechanism of cemented hydrate-bearing sand at microscales

    Science.gov (United States)

    Yoneda, Jun; Jin, Yusuke; Katagiri, Jun; Tenma, Norio

    2016-07-01

    On the basis of hypothetical particle-level mechanisms, several constitutive models of hydrate-bearing sediments have been proposed previously for gas production. However, to the best of our knowledge, the microstructural large-strain behaviors of hydrate-bearing sediments have not been reported to date because of the experimental challenges posed by the high-pressure and low-temperature testing conditions. Herein, a novel microtriaxial testing apparatus was developed, and the mechanical large-strain behavior of hydrate-bearing sediments with various hydrate saturation values (Sh = 0%, 39%, and 62%) was analyzed using microfocus X-ray computed tomography. Patchy hydrates were observed in the sediments at Sh = 39%. The obtained stress-strain relationships indicated strengthening with increasing hydrate saturation and a brittle failure mode of the hydrate-bearing sand. Localized deformations were quantified via image processing at the submillimeter and micrometer scale. Shear planes and particle deformation and/or rotation were detected, and the shear band thickness decreased with increasing hydrate saturation.

  10. Determination of the Formula of a Hydrate: A Greener Alternative

    Science.gov (United States)

    Klingshirn, Marc A.; Wyatt, Allison F.; Hanson, Robert M.; Spessard, Gary O.

    2008-01-01

    We are currently in the process of incorporating green chemistry throughout the chemistry curriculum. In this article we describe how we applied the principles of green chemistry in one of our first-semester general chemistry courses, specifically in relation to the determination of the formula of a hydrate. We utilize a copper hydrate salt that…

  11. Hydration dynamics of the collagen triple helix by NMR.

    Science.gov (United States)

    Melacini, G; Bonvin, A M; Goodman, M; Boelens, R; Kaptein, R

    2000-07-28

    The hydration of the collagen-like Ac-(Gly-Pro-Hyp)(6)-NH(2) triple-helical peptide in solution was investigated using an integrated set of high-resolution NMR hydration experiments, including different recently developed exchange-network editing methods. This approach was designed to explore the hydration dynamics in the proximity of labile groups, such as the hydroxyproline hydroxyl group, and revealed that the first shell of hydration in collagen-like triple helices is kinetically labile with upper limits for water molecule residence times in the nanosecond to sub-nanosecond range. This result is consistent with a "hopping" hydration model in which solvent molecules are exchanged in and out of solvation sites at a rate that is not directly correlated to the degree of site localization. The hopping model thus reconciles the dynamic view of hydration revealed by NMR with the previously suggested partially ordered semi-clathrate-like cylinder of hydration. In addition, the nanosecond to sub-nanosecond upper limits for water molecule residence times imply that hydration-dehydration events are not likely to be the rate-limiting step for triple helix self-recognition, complementing previous investigations on water dynamics in collagen fibers. This study has also revealed labile proton features expected to facilitate the characterization of the structure and folding of triple helices in collagen peptides.

  12. INFLUENCE OF CHEMICAL ADDITIVES ON GAS HYDRATE FORMATION

    Institute of Scientific and Technical Information of China (English)

    TANG Cuiping; FAN Shuanshi

    2003-01-01

    One surfactant as sodium dodecyl sulfate (SDS) and one synthesized sample as gas hydrate inhibitor are introduced in this paper. Through experiments we prove sodium dodecyl sulfate can accelerate the formation rate of gas hydrate and the synthesized sample can inhibit the formation and growth.

  13. Lactate Dehydrogenase Catalysis: Roles of Keto, Hydrated, and Enol Pyruvate

    Science.gov (United States)

    Meany, J. E.

    2007-01-01

    Many carbonyl substrates of oxidoreductase enzymes undergo hydration and enolization so that these substrate systems are partitioned between keto, hydrated (gem-diol), and enol forms in aqueous solution. Some oxidoreductase enzymes are subject to inhibition by high concentrations of substrate. For such enzymes, two questions arise pertaining to…

  14. Lactate Dehydrogenase Catalysis: Roles of Keto, Hydrated, and Enol Pyruvate

    Science.gov (United States)

    Meany, J. E.

    2007-01-01

    Many carbonyl substrates of oxidoreductase enzymes undergo hydration and enolization so that these substrate systems are partitioned between keto, hydrated (gem-diol), and enol forms in aqueous solution. Some oxidoreductase enzymes are subject to inhibition by high concentrations of substrate. For such enzymes, two questions arise pertaining to…

  15. Gas hydrates and magnetism : comparative geological settings for diagenetic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Esteban, L.; Enkin, R.J. [Natural Resources Canada, Sidney, BC (Canada). Geological Survey of Canada; Hamilton, T. [Camosun College, Victoria, BC (Canada)

    2008-07-01

    Geophysical and geochemical methods assist in locating and quantifying natural gas hydrate deposits. They are also useful in understanding these resources, their climate impacts and their potential role in geohazards. In order to understand the mechanisms of gas hydrate formation and its natural distribution in sediments, magnetic studies were conducted on cores from three different geological settings. This paper presented the results of a detailed magnetic investigation, as well as petrological observations, that were conducted on cores from a permafrost setting in the Mackenzie Delta located in the Canadian Northwest Territories Mallik region, and two marine settings, from the Cascadia margin off Vancouver Island and the Indian National Gas Hydrate Program from the Bengal Fan. The paper provided background information on the permafrost setting in Mallik region of the Mackenzie Delta as well as the Cascadia margin. The magnetic properties of gas hydrate bearing sediments were found to be a combination of the original detrital content and the diagenetic transformations of iron minerals caused by the unique environment produced by gas hydrate formation. The availability of methane to provide food for bacteria coupled with the concentration of solutes outside gas hydrate accumulation zones led to the creation of iron sulphides. These new minerals were observable using magnetic techniques, which help in delineating the gas hydrate formation mechanism and may be developed into new geophysical methods of gas hydrate exploration. 7 refs., 7 figs.

  16. Salinity-buffered methane hydrate formation and dissociation in gas-rich systems

    Science.gov (United States)

    You, Kehua; Kneafsey, Timothy J.; Flemings, Peter B.; Polito, Peter; Bryant, Steven L.

    2015-02-01

    Methane hydrate formation and dissociation are buffered by salinity in a closed system. During hydrate formation, salt excluded from hydrate increases salinity, drives the system to three-phase (gas, water, and hydrate phases) equilibrium, and limits further hydrate formation and dissociation. We developed a zero-dimensional local thermodynamic equilibrium-based model to explain this concept. We demonstrated this concept by forming and melting methane hydrate from a partially brine-saturated sand sample in a controlled laboratory experiment by holding pressure constant (6.94 MPa) and changing temperature stepwise. The modeled methane gas consumptions and hydrate saturations agreed well with the experimental measurements after hydrate nucleation. Hydrate dissociation occurred synchronously with temperature increase. The exception to this behavior is that substantial subcooling (6.4°C in this study) was observed for hydrate nucleation. X-ray computed tomography scanning images showed that core-scale hydrate distribution was heterogeneous. This implied core-scale water and salt transport induced by hydrate formation. Bulk resistivity increased sharply with initial hydrate formation and then decreased as the hydrate ripened. This study reproduced the salinity-buffered hydrate behavior interpreted for natural gas-rich hydrate systems by allowing methane gas to freely enter/leave the sample in response to volume changes associated with hydrate formation and dissociation. It provides insights into observations made at the core scale and log scale of salinity elevation to three-phase equilibrium in natural hydrate systems.

  17. Seismic-Scale Rock Physics of Methane Hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Amos Nur

    2009-01-08

    We quantify natural methane hydrate reservoirs by generating synthetic seismic traces and comparing them to real seismic data: if the synthetic matches the observed data, then the reservoir properties and conditions used in synthetic modeling might be the same as the actual, in-situ reservoir conditions. This approach is model-based: it uses rock physics equations that link the porosity and mineralogy of the host sediment, pressure, and hydrate saturation, and the resulting elastic-wave velocity and density. One result of such seismic forward modeling is a catalogue of seismic reflections of methane hydrate which can serve as a field guide to hydrate identification from real seismic data. We verify this approach using field data from known hydrate deposits.

  18. AN EXPERIMENTAL STUDY ON HYDRATION OF VARIOUS MAGNESIA RAW MATERIALS

    Directory of Open Access Journals (Sweden)

    Ilona Jastrzebska

    2015-03-01

    Full Text Available Hydration of various commercially available magnesia raw materials were studied under hydrothermal conditions. Raw materials were characterized by XRD, XRF, TG/DTA and SEM/EDS methods. Subsequently, they were subjected to hydration test conducted at temperature of 162oC and presuure of 552 kPa according to ASTM C 554-92 standard. The evolution of phase, microstructure and physicochemical behaviour after hydration test were analysed by XRD, DTA/TG and SEM/EDS. The results showed that presence of the specific secondary phases plays a crucial role in preventing MgO grains against the hydration. Merwinite, monticellite, magnesioferrite and srebrnodolskite were found to constitute protector-like phases that inibit hydration process of magnesia.

  19. Calorimetric Determination of Enthalpy of Formation of Natural Gas Hydrates

    Institute of Scientific and Technical Information of China (English)

    高军; KennethN.Marsh

    2003-01-01

    This paper reports the measurements of enthalpies of natural gas hydrates in typical natural gas mixture containing methane, ethane, propane and iso-butane at pressure in the vicinity of 2000 kPa (300 psi) and 6900 kPa(1000psi). The measurements were made in a multi-cell differential scanning calorimeter using modified high pressure cells. The enthalpy of water and the enthalpy of dissociation of the gas hydrate were determined from the calorimeter response during slow temperature scanning at constant pressure. The amount of gas released from the dissociation of hydrate was determined from the pumped volume of the high pressure pump. The occupation ratio (mole ratio) of the water to gas and the enthalpy of hydrate formation are subject to uncertainty of 1.5%.The results show that the enthalpy of hydrate formation and the occupation ratio are essentially independent of pressure.

  20. Methane hydrate formation and dissociation in synthetic seawater

    Institute of Scientific and Technical Information of China (English)

    Vikash Kumar Saw; Iqbal Ahmad; Ajay Mandal; G.Udayabhanu; Sukumar Laik

    2012-01-01

    The formation and dissociation of methane gas hydrate at an interface between synthetic seawater (SSW) and methane gas have been experimentally investigated in the present work.The amount of gas consumed during hydrate formation has been calculated using the real gas equation.Induction time for the formation of hydrate is found to depend on the degree of subcooling.All the experiments were conducted in quiescent system with initial cell pressure of 11.14 MPa.Salinity effects on the onset pressure and temperature of hydrate formation are also observed.The dissociation enthalpies of methane hydrate in synthetic seawater were determined by Clausius-Clapeyron equation based on the measured phase equilibrium data.The dissociation data have been analyzed by existing models and compared with the reported data.

  1. Fundamental challenges to methane recovery from gas hydrates

    Science.gov (United States)

    Servio, P.; Eaton, M.W.; Mahajan, D.; Winters, W.J.

    2005-01-01

    The fundamental challenges, the location, magnitude, and feasibility of recovery, which must be addressed to recover methane from dispersed hydrate sources, are presented. To induce dissociation of gas hydrate prior to methane recovery, two potential methods are typically considered. Because thermal stimulation requires a large energy input, it is less economically feasible than depressurization. The new data will allow the study of the effect of pressure, temperature, diffusion, porosity, tortuosity, composition of gas and water, and porous media on gas-hydrate production. These data also will allow one to improve existing models related to the stability and dissociation of sea floor hydrates. The reproducible kinetic data from the planned runs together with sediment properties will aid in developing a process to economically recover methane from a potential untapped hydrate source. The availability of plentiful methane will allow economical and large-scale production of methane-derived clean fuels to help avert future energy crises.

  2. Theoretical description of biomolecular hydration - Application to A-DNA

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, A.E.; Hummer, G. [Los Alamos National Laboratory, NM (United States); Soumpasis, D.M. [Max Planck Inst. for Biophysical Chemistry, Goettingen (Germany)

    1994-12-31

    The local density of water molecules around a biomolecule is constructed from calculated two- and three-points correlation functions of polar solvents in water using a Potential-of-Mean-Force (PMF) expansion. As a simple approximation, the hydration of all polar (including charged) groups in a biomolecule is represented by the hydration of water oxygen in bulk water, and the effect of non-polar groups on hydration are neglected, except for excluded volume effects. Pair and triplet correlation functions are calculated by molecular dynamics simulations. We present calculations of the structural hydration for ideal A-DNA molecules with sequences [d(CG){sub 5}]{sub 2} and [d(C{sub 5}G{sub 5})]{sub 2}. We find that this method can accurately reproduce the hydration patterns of A-DNA observed in neutron diffraction experiments on oriented DNA fibers.

  3. Hydration of Portland cement with additions of calcium sulfoaluminates

    Energy Technology Data Exchange (ETDEWEB)

    Le Saout, Gwenn, E-mail: gwenn.le-saout@mines-ales.fr [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Lothenbach, Barbara [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Hori, Akihiro [DENKA Chemicals GmbH, Wehrhahn-Center, Cantadorstr. 3, D-40211 Duesseldorf (Germany); Higuchi, Takayuki [Denki Kagaku Kogyo Kabushiki Kaisha (DENKA), Omi, Itoigawa, Niigata, 949-0393 (Japan); Winnefeld, Frank [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)

    2013-01-15

    The effect of mineral additions based on calcium aluminates on the hydration mechanism of ordinary Portland cement (OPC) was investigated using isothermal calorimetry, thermal analysis, X-ray diffraction, scanning electron microscopy, solid state nuclear magnetic resonance and pore solution analysis. Results show that the addition of a calcium sulfoaluminate cement (CSA) to the OPC does not affect the hydration mechanism of alite but controls the aluminate dissolution. In the second blend investigated, a rapid setting cement, the amorphous calcium aluminate reacts very fast to ettringite. The release of aluminum ions strongly retards the hydration of alite but the C-S-H has a similar composition as in OPC with no additional Al to Si substitution. As in CSA-OPC, the aluminate hydration is controlled by the availability of sulfates. The coupling of thermodynamic modeling with the kinetic equations predicts the amount of hydrates and pore solution compositions as a function of time and validates the model in these systems.

  4. The Pore Structure and Hydration Performance of Sulphoaluminate MDF Cement

    Institute of Scientific and Technical Information of China (English)

    HUANG Cong-yun; YUAN Run-zhang; LONG Shi-zong

    2004-01-01

    The hydration and pore structure of sulphoaluminate MDF cement were studied by X-ray diffractometer ( XRD ), scanning electron microscope (SEM) and mercury intrusion porosimeter ( MIP ) etc. The ex-perimental results indicate that hydration products of the materials are entringites ( Aft ), aluminium hydroxide andCSH (Ⅰ) gel etc. Due to its very low water-cement ratio, hydration function is only confined to the surfaces of ce-ment grains, and there is a lot of sulphoaluminate cement in the hardenite which is unhydrated yet. Hydration re-action was rapidly carried under the condition of the heat-pressing. Therefore cement hydrates Aft, CSH (Ⅰ) andaluminium hydroxide gel fill in pores. The expansibility of Aft makes the porosity of MDF cement lower ( less than1 percent ) and the size of pore smaller (80 percent pore was less than 250A), and enhances its strength.

  5. Volatile inventories in clathrate hydrates formed in the primordial nebula

    CERN Document Server

    Mousis, O; Picaud, S; Cordier, D

    2010-01-01

    Examination of ambient thermodynamic conditions suggest that clathrate hydrates could exist in the martian permafrost, on the surface and in the interior of Titan, as well as in other icy satellites. Clathrate hydrates probably formed in a significant fraction of planetesimals in the solar system. Thus, these crystalline solids may have been accreted in comets, in the forming giant planets and in their surrounding satellite systems. In this work, we use a statistical thermodynamic model to investigate the composition of clathrate hydrates that may have formed in the primordial nebula. In our approach, we consider the formation sequence of the different ices occurring during the cooling of the nebula, a reasonable idealization of the process by which volatiles are trapped in planetesimals. We then determine the fractional occupancies of guests in each clathrate hydrate formed at given temperature. The major ingredient of our model is the description of the guest-clathrate hydrate interaction by a spherically a...

  6. Heat of Hydration of Low Activity Cementitious Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Nasol, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-07-23

    During the curing of secondary waste grout, the hydraulic materials in the dry mix react exothermally with the water in the secondary low-activity waste (LAW). The heat released, called the heat of hydration, can be measured using a TAM Air Isothermal Calorimeter. By holding temperature constant in the instrument, the heat of hydration during the curing process can be determined. This will provide information that can be used in the design of a waste solidification facility. At the Savannah River National Laboratory (SRNL), the heat of hydration and other physical properties are being collected on grout prepared using three simulants of liquid secondary waste generated at the Hanford Site. From this study it was found that both the simulant and dry mix each had an effect on the heat of hydration. It was also concluded that the higher the cement content in the dry materials mix, the greater the heat of hydration during the curing of grout.

  7. Nasogastric Hydration in Infants with Bronchiolitis Less Than 2 Months of Age.

    Science.gov (United States)

    Oakley, Ed; Bata, Sonny; Rengasamy, Sharmila; Krieser, David; Cheek, John; Jachno, Kim; Babl, Franz E

    2016-11-01

    To determine whether nasogastric hydration can be used in infants less than 2 months of age with bronchiolitis, and characterize the adverse events profile of these infants compared with infants given intravenous (IV) fluid hydration. A descriptive retrospective cohort study of children with bronchiolitis under 2 months of age admitted for hydration at 3 centers over 3 bronchiolitis seasons was done. We determined type of hydration (nasogastric vs IV fluid hydration) and adverse events, intensive care unit admission, and respiratory support. Of 491 infants under 2 months of age admitted with bronchiolitis, 211 (43%) received nonoral hydration: 146 (69%) via nasogastric hydration and 65 (31%) via IV fluid hydration. Adverse events occurred in 27.4% (nasogastric hydration) and 23.1% (IV fluid hydration), difference of 4.3%; 95%CI (-8.2 to 16.9), P = .51. The majority of adverse events were desaturations (21.9% nasogastric hydration vs 21.5% IV fluid hydration, difference 0.4%; [-11.7 to 12.4], P = .95). There were no pulmonary aspirations in either group. Apneas and bradycardias were similar in each group. IV fluid hydration use was positively associated with intensive care unit admission (38.5% IV fluid hydration vs 19.9% nasogastric hydration; difference 18.6%, [5.1-32.1], P = .004); and use of ventilation support (27.7% IV fluid hydration vs 15.1% nasogastric hydration; difference 12.6 [0.3-23], P = .03). Fewer infants changed from nasogastric hydration to IV fluid hydration than from IV fluid hydration to nasogastric hydration (12.3% vs 47.7%; difference -35.4% [-49 to -22], P bronchiolitis. Nasogastric hydration and IV fluid hydration had similar rates of complications. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Linking basin-scale and pore-scale gas hydrate distribution patterns in diffusion-dominated marine hydrate systems

    Science.gov (United States)

    Nole, Michael; Daigle, Hugh; Cook, Ann E.; Hillman, Jess I. T.; Malinverno, Alberto

    2017-02-01

    The goal of this study is to computationally determine the potential distribution patterns of diffusion-driven methane hydrate accumulations in coarse-grained marine sediments. Diffusion of dissolved methane in marine gas hydrate systems has been proposed as a potential transport mechanism through which large concentrations of hydrate can preferentially accumulate in coarse-grained sediments over geologic time. Using one-dimensional compositional reservoir simulations, we examine hydrate distribution patterns at the scale of individual sand layers (1-20 m thick) that are deposited between microbially active fine-grained material buried through the gas hydrate stability zone (GHSZ). We then extrapolate to two-dimensional and basin-scale three-dimensional simulations, where we model dipping sands and multilayered systems. We find that properties of a sand layer including pore size distribution, layer thickness, dip, and proximity to other layers in multilayered systems all exert control on diffusive methane fluxes toward and within a sand, which in turn impact the distribution of hydrate throughout a sand unit. In all of these simulations, we incorporate data on physical properties and sand layer geometries from the Terrebonne Basin gas hydrate system in the Gulf of Mexico. We demonstrate that diffusion can generate high hydrate saturations (upward of 90%) at the edges of thin sands at shallow depths within the GHSZ, but that it is ineffective at producing high hydrate saturations throughout thick (greater than 10 m) sands buried deep within the GHSZ. Furthermore, we find that hydrate in fine-grained material can preserve high hydrate saturations in nearby thin sands with burial.Plain Language SummaryThis study combines one-, two-, and three-dimensional simulations to explore one potential process by which methane dissolved in water beneath the seafloor can be converted into solid methane hydrate. This work specifically examines one end-member methane transport

  9. Evaluation of a rapid hydration protocol: Safety and effectiveness.

    Science.gov (United States)

    Meredith, Sean; Hilliard, Jane; Vaillancourt, Regis

    2017-06-01

    Background The Children's Hospital of Eastern Ontario (CHEO) has implemented a rapid hydration protocol that may reduce the time required to achieve urine specific gravity and pH targets prior to chemotherapy. Objective The aim of this study was to determine if a rapid hydration protocol resulted in a shorter time to chemotherapy administration and during peak staffing levels without increasing adverse effects. Methods A retrospective chart review was conducted using data from electronic and paper medical charts, the hematology/oncology whiteboard, and video recordings. Patients who received cyclophosphamide, methotrexate, cisplatin and ifosfamide during the study period were included in the chart review. A urine specific gravity of ≤1.01, and in most cases a urine pH ≥7 was required to begin chemotherapy. Differences in time parameters between the standard and rapid hydration protocols were measured. Comparable parameters included the time from the start of pre-chemotherapy hydration to meeting urine targets, time from starting hydration to administration of chemotherapy, length of hospital stay and the number of chemotherapy administrations that were initiated prior to the nursing shift change at 19:30 h. Results Data were collected from 116 pre-chemotherapy intravenous hydration events administered to 25 different patients. There was a shorter time required to reach urine specific gravity and pH targets with the rapid hydration protocol compared to the standard hydration protocol, which translated into initiating chemotherapy sooner. There was also a shorter overall length of hospital stay and administration of chemotherapy occurred before the nursing shift change more often in the rapid hydration cohort compared to those patients who received the standard hydration protocol. There were no significant differences in adverse effects between the groups. Conclusion Patients receiving rapid hydration had a shorter time to chemotherapy administration and had a

  10. Electron-Induced Secondary Electron Emission Properties of MgO/Au Composite Thin Film Prepared by Magnetron Sputtering

    Science.gov (United States)

    Li, Jie; Hu, Wenbo; Wei, Qiang; Wu, Shengli; Hua, Xing; Zhang, Jintao

    2016-12-01

    As a type of electron-induced secondary electron emitter, MgO/Au composite thin film was prepared by reactive magnetron sputtering of individual Mg target and Au target, and the effects of key process parameters on its surface morphology and secondary electron emission (SEE) properties were investigated. It is found that to deposit a NiO buffer layer on the substrate is conducive to the subsequent growth of MgO grains owing to the lattice matching. The gold addition can raise the electrical conductivity of MgO film and further suppress the surface charging. However, the gold deposition would interfere with the MgO crystallization and increase the surface roughness of MgO/Au film. Therefore, MgO/Au composite thin film with a NiO buffer layer and proper deposition times of MgO and Au can achieve superior SEE properties due to good MgO crystallization, low surface roughness and reasonable electrical conductivity. The optimized MgO/Au composite thin film has a higher SEE coefficient and a lower 1-h SEE degradation rate under electron beam bombardment in comparison with MgO film.

  11. Disentangling volumetric and hydrational properties of proteins.

    Science.gov (United States)

    Voloshin, Vladimir P; Medvedev, Nikolai N; Smolin, Nikolai; Geiger, Alfons; Winter, Roland

    2015-02-05

    We used molecular dynamics simulations of a typical monomeric protein, SNase, in combination with Voronoi-Delaunay tessellation to study and analyze the temperature dependence of the apparent volume, Vapp, of the solute. We show that the void volume, VB, created in the boundary region between solute and solvent, determines the temperature dependence of Vapp to a major extent. The less pronounced but still significant temperature dependence of the molecular volume of the solute, VM, is essentially the result of the expansivity of its internal voids, as the van der Waals contribution to VM is practically independent of temperature. Results for polypeptides of different chemical nature feature a similar temperature behavior, suggesting that the boundary/hydration contribution seems to be a universal part of the temperature dependence of Vapp. The results presented here shine new light on the discussion surrounding the physical basis for understanding and decomposing the volumetric properties of proteins and biomolecules in general.

  12. Irradiation effects in hydrated zirconium molybdate

    Science.gov (United States)

    Fourdrin, C.; Esnouf, S.; Dauvois, V.; Renault, J.-P.; Venault, L.; Tabarant, M.; Durand, D.; Chenière, A.; Lamouroux-Lucas, C.; Cochin, F.

    2012-07-01

    Hydrated zirconium molybdate is a precipitate formed during the process of spent nuclear fuel dissolution. In order to study the radiation stability of this material, we performed gamma and electron irradiation in a dose range of 10-100 kGy. XRD patterns showed that the crystalline structure is not affected by irradiation. However, the yellow original sample exhibits a blue-grey color after exposure. The resulting samples were analyzed by means of EPR and diffuse reflectance spectroscopy. Two sites for trapped electrons were evidenced leading to a d1 configuration responsible for the observed coloration. Moreover, a third defect corresponding to a hole trapped on oxygen was observed after electron irradiation at low temperature.

  13. High-pressure structures of methane hydrate

    CERN Document Server

    Hirai, H; Fujihisa, H; Sakashita, M; Katoh, E; Aoki, K; Yamamoto, Y; Nagashima, K; Yagi, T

    2002-01-01

    Three high-pressure structures of methane hydrate, a hexagonal structure (str. A) and two orthorhombic structures (str. B and str. C), were found by in situ x-ray diffractometry and Raman spectroscopy. The well-known structure I (str. I) decomposed into str. A and fluid at 0.8 GPa. Str. A transformed into str. B at 1.6 GPa, and str. B further transformed into str. C at 2.1 GPa which survived above 7.8 GPa. The fluid solidified as ice VI at 1.4 GPa, and the ice VI transformed to ice VII at 2.1 GPa. The bulk moduli, K sub 0 , for str. I, str. A, and str. C were calculated to be 7.4, 9.8, and 25.0 GPa, respectively.

  14. DNA under Force: Mechanics, Electrostatics, and Hydration

    Directory of Open Access Journals (Sweden)

    Jingqiang Li

    2015-02-01

    Full Text Available Quantifying the basic intra- and inter-molecular forces of DNA has helped us to better understand and further predict the behavior of DNA. Single molecule technique elucidates the mechanics of DNA under applied external forces, sometimes under extreme forces. On the other hand, ensemble studies of DNA molecular force allow us to extend our understanding of DNA molecules under other forces such as electrostatic and hydration forces. Using a variety of techniques, we can have a comprehensive understanding of DNA molecular forces, which is crucial in unraveling the complex DNA functions in living cells as well as in designing a system that utilizes the unique properties of DNA in nanotechnology.

  15. THz Medical Imaging: in vivo Hydration Sensing

    Science.gov (United States)

    Taylor, Zachary D.; Singh, Rahul S.; Bennett, David B.; Tewari, Priyamvada; Kealey, Colin P.; Bajwa, Neha; Culjat, Martin O.; Stojadinovic, Alexander; Lee, Hua; Hubschman, Jean-Pierre; Brown, Elliott R.; Grundfest, Warren S.

    2015-01-01

    The application of THz to medical imaging is experiencing a surge in both interest and federal funding. A brief overview of the field is provided along with promising and emerging applications and ongoing research. THz imaging phenomenology is discussed and tradeoffs are identified. A THz medical imaging system, operating at ~525 GHz center frequency with ~125 GHz of response normalized bandwidth is introduced and details regarding principles of operation are provided. Two promising medical applications of THz imaging are presented: skin burns and cornea. For burns, images of second degree, partial thickness burns were obtained in rat models in vivo over an 8 hour period. These images clearly show the formation and progression of edema in and around the burn wound area. For cornea, experimental data measuring the hydration of ex vivo porcine cornea under drying is presented demonstrating utility in ophthalmologic applications. PMID:26085958

  16. Hydration Structure of the Quaternary Ammonium Cations

    KAUST Repository

    Babiaczyk, Wojtek Iwo

    2010-11-25

    Two indicators of the hydropathicity of small solutes are introduced and tested by molecular dynamics simulations. These indicators are defined as probabilities of the orientation of water molecules\\' dipoles and hydrogen bond vectors, conditional on a generalized distance from the solute suitable for arbitrarily shaped molecules. Using conditional probabilities, it is possible to distinguish features of the distributions in close proximity of the solute. These regions contain the most significant information on the hydration structure but cannot be adequately represented by using, as is usually done, joint distance-angle probability densities. Our calculations show that using our indicators a relative hydropathicity scale for the interesting test set of the quaternary ammonium cations can be roughly determined. © 2010 American Chemical Society.

  17. Phase behavior and hydration of silk fibroin.

    Science.gov (United States)

    Sohn, Sungkyun; Strey, Helmut H; Gido, Samuel P

    2004-01-01

    The osmotic stress method was applied to study the thermodynamics of supramolecular self-assembly phenomena in crystallizable segments of Bombyx mori silkworm silk fibroin. By controlling compositions and phases of silk fibroin solution, the method provided a means for the direct investigation of microscopic and thermodynamic details of these intermolecular interactions in aqueous media. It is apparent that as osmotic pressure increases, silk fibroin molecules are crowded together to form silk I structure and then with further increase in osmotic pressure become an antiparallel beta-sheet structure, silk II. A partial ternary phase diagram of water-silk fibroin-LiBr was constructed based on the results. The results provide quantitative evidence that the silk I structure must contain water of hydration. The enhanced control over structure and phase behavior using osmotic stress, as embodied in the phase diagram, could potentially be utilized to design a new route for water-based wet spinning of regenerated silk fibroin.

  18. Chlorine inactivation of Tubifex tubifex in drinking water and the synergistic effect of sequential inactivation with UV irradiation and chlorine.

    Science.gov (United States)

    Nie, Xiao-Bao; Li, Zhi-Hong; Long, Yuan-Nan; He, Pan-Pan; Xu, Chao

    2017-06-01

    The inactivation of Tubifex tubifex is important to prevent contamination of drinking water. Chlorine is a widely-used disinfectant and the key factor in the inactivation of T. tubifex. This study investigated the inactivation kinetics of chlorine on T. tubifex and the synergistic effect of the sequential use of chlorine and UV irradiation. The experimental results indicated that the Ct (concentration × timereaction) concept could be used to evaluate the inactivation kinetics of T. tubifex with chlorine, thus allowing for the use of a simpler Ct approach for the assessment of T. tubifex chlorine inactivation requirements. The inactivation kinetics of T. tubifex by chlorine was found to be well-fitted to a delayed pseudo first-order Chick-Watson expression. Sequential experiments revealed that UV irradiation and chlorine worked synergistically to effectively inactivate T. tubifex as a result of the decreased activation energy, Ea, induced by primary UV irradiation. Furthermore, the inactivation effectiveness of T. tubifex by chlorine was found to be affected by several drinking water quality parameters including pH, turbidity, and chemical oxygen demand with potassium permanganate (CODMn) concentration. High pH exhibited pronounced inactivation effectiveness and the decrease in turbidity and CODMn concentrations contributed to the inactivation of T. tubifex.

  19. Influence of Physical Activity and Ambient Temperature on Hydration: The European Hydration Research Study (EHRS

    Directory of Open Access Journals (Sweden)

    Ricardo Mora-Rodriguez

    2016-04-01

    Full Text Available This study explored the effects of physical activity (PA and ambient temperature on water turnover and hydration status. Five-hundred seventy three healthy men and women (aged 20–60 years from Spain, Greece and Germany self-reported PA, registered all food and beverage intake, and collected 24-h urine during seven consecutive days. Fasting blood samples were collected at the onset and end of the study. Food moisture was assessed using nutritional software to account for all water intake which was subtracted from daily urine volume to allow calculation of non-renal water loss (i.e., mostly sweating. Hydration status was assessed by urine and blood osmolality. A negative association was seen between ambient temperature and PA (r = −0.277; p < 0.001. Lower PA with high temperatures did not prevent increased non-renal water losses (i.e., sweating and elevated urine and blood osmolality (r = 0.218 to 0.163 all p < 0.001. When summer and winter data were combined PA was negatively associated with urine osmolality (r = −0.153; p = 0.001. Our data suggest that environmental heat acts to reduce voluntary PA but this is not sufficient to prevent moderate dehydration (increased osmolality. On the other hand, increased PA is associated with improved hydration status (i.e., lower urine and blood osmolality.

  20. Virus inactivation by protein denaturants used in affinity chromatography.

    Science.gov (United States)

    Roberts, Peter L; Lloyd, David

    2007-10-01

    Virus inactivation by a number of protein denaturants commonly used in gel affinity chromatography for protein elution and gel recycling has been investigated. The enveloped viruses Sindbis, herpes simplex-1 and vaccinia, and the non-enveloped virus polio-1 were effectively inactivated by 0.5 M sodium hydroxide, 6 M guanidinium thiocyanate, 8 M urea and 70% ethanol. However, pH 2.6, 3 M sodium thiocyanate, 6 M guanidinium chloride and 20% ethanol, while effectively inactivating the enveloped viruses, did not inactivate polio-1. These studies demonstrate that protein denaturants are generally effective for virus inactivation but with the limitation that only some may inactivate non-enveloped viruses. The use of protein denaturants, together with virus reduction steps in the manufacturing process should ensure that viral cross contamination between manufacturing batches of therapeutic biological products is prevented and the safety of the product ensured.

  1. Detection and Appraisal of Gas Hydrates: Indian Scenario

    Science.gov (United States)

    Sain, K.

    2009-04-01

    Gas hydrates, found in shallow sediments of permafrost and outer continental margins, are crystalline form of methane and water. The carbon within global gas hydrates is estimated two times the carbon contained in world-wide fossil fuels. It is also predicted that 15% recovery of gas hydrates can meet the global energy requirement for the next 200 years. Several parameters like bathymetry, seafloor temperature, sediment thickness, rate of sedimentation and total organic carbon content indicate very good prospect of gas hydrates in the vast offshore regions of India. Methane stored in the form of gas hydrates within the Indian exclusive economic zone is estimated to be few hundred times the country's conventional gas reserve. India produces less than one-third of her oil requirement and gas hydrates provide great hopes as a viable source of energy in the 21st century. Thus identification and quantitative assessment of gas hydrates are very important. By scrutiny and reanalysis of available surface seismic data, signatures of gas hydrates have been found out in the Kerala-Konkan and Saurashtra basins in the western margin, and Krishna-Godavari, Mahanadi and Andaman regions in the eastern margin of India by mapping the bottom simulating reflector or BSR based on its characteristic features. In fact, the coring and drilling in 2006 by the Indian National Gas Hydrate Program have established the ground truth in the eastern margin. It has become all the more important now to identify further prospective regions with or without BSR; demarcate the lateral/areal extent of gas hydrate-bearing sediments and evaluate their resource potential in both margins of India. We have developed various approaches based on seismic traveltime tomography; waveform inversion; amplitude versus offset (AVO) modeling; AVO attributes; seismic attributes and rock physics modeling for the detection, delineation and quantification of gas-hydrates. The blanking, reflection strength, instantaneous

  2. RESEARCH ON COUPLED RELATIONSHIP BETWEEN HYDRATION NUMBER WITH RAMAN SPECTRUM

    Institute of Scientific and Technical Information of China (English)

    LEI Huaiyan; LIU Zhihong; FAN Shuanshi; XU Maoquan; GUAN Baocong

    2003-01-01

    As we know, there are three structures-sⅠ, sⅡ, and sH, with hydrocarbonate gas hydrate.Because of those special structures characteristics and potentail large fossil energy resource, gas hydrate play an important role in natural carbonate cycle system. In this paper, CH4, CO2, C3H8, and CH4 +CO2 system have been experimental performed in order to model hydrate formation and discomposition and to obtain hydrate stability conditions of tempreature and pressure. The results from laboratory using Raman spectra show that Raman spectrascopy is a effective tool to identify hydrate structure. Raman spectra of clathrate hydrate guest molecules are presented for two structure (sⅠ and sⅡ) in the following systems: CH4, CO2, C3 H8. Relatively occupancy of CH4 in the large and small cavities of sⅠ were determined by deconvoluting the v1 symmetric bands, resulting in hydration numbers of 6.04±0.03. The freqyuency of the v1 bands for CH4 in structures Ⅰ and Ⅱ differ statistically. The large cavities were measured to be almost fully occupied by CH4 and CO2, whereas only a small fraction of the small cavities are occupied by CH4. No CO2 was found in the small cavities.

  3. The effect of hydrate promoters on gas uptake.

    Science.gov (United States)

    Xu, Chun-Gang; Yu, Yi-Song; Ding, Ya-Long; Cai, Jing; Li, Xiao-Sen

    2017-08-16

    Gas hydrate technology is considered as a promising technology in the fields of gas storage and transportation, gas separation and purification, seawater desalination, and phase-change thermal energy storage. However, to date, the technology is still not commercially used mainly due to the low gas hydrate formation rate and the low gas uptake. In this study, the effect of hydrate promoters on gas uptake was systematically studied and analyzed based on hydrate-based CH4 storage and CO2 capture from CO2/H2 gas mixture experiments. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and gas chromatography (GC) were employed to analyze the microstructures and gas compositions. The results indicate that the effect of the hydrate promoter on the gas uptake depends on the physical and chemical properties of the promoter and gas. A strong polar ionic promoter is not helpful towards obtaining the ideal gas uptake because a dense hydrate layer is easily formed at the gas-liquid interface, which hinders gas diffusion from the gas phase to the bulk solution. For a weak polar or non-polar promoter, the gas uptake depends on the dissolution characteristics among the different substances in the system. The lower the mutual solubility among the substances co-existing in the system, the higher the independence among the substances in the system; this is so that each phase has an equal chance to occupy the hydrate cages without or with small interactions, finally leading to a relatively high gas uptake.

  4. Dynamics of Hydration Water in Sugars and Peptides Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Perticaroli, Stefania [ORNL; Nakanishi, Masahiro [ORNL; Pashkovski, Eugene [Unilever R& D Trumbull, Trumbull CT; Sokolov, Alexei P [ORNL

    2013-01-01

    We analyzed solute and solvent dynamics of sugars and peptides aqueous solutions using extended epolarized light scattering (EDLS) and broadband dielectric spectroscopies (BDS). Spectra measured with both techniques reveal the same mechanism of rotational diffusion of peptides molecules. In the case of sugars, this solute reorientational relaxation can be isolated by EDLS measurements, whereas its ontribution to the dielectric spectra is almost negligible. In the presented analysis, we characterize the hydration water in terms of hydration number and retardation ratio between relaxation times of hydration and bulk water. Both techniques provide similar estimates of . The retardation imposed on the hydration water by sugars is 3.3 1.3 and involves only water molecules hydrogen-bonded (HB) to solutes ( 3 water molecules per sugar OH-group). In contrast, polar peptides cause longer range erturbations beyond the first hydration shell, and between 2.8 and 8, increasing with the number of chemical groups engaged in HB formation. We demonstrate that chemical heterogeneity and specific HB interactions play a crucial role in hydration dynamics around polar solutes. The obtained results help to disentangle the role of excluded volume and enthalpic contributions in dynamics of hydration water at the interface with biological molecules.

  5. Hydrates of nat­ural gas in continental margins

    Science.gov (United States)

    Kvenvolden, K.A.; Barnard, L.A.

    1982-01-01

    Natural gas hydrates in continental margin sediment can be inferred from the widespread occurrence of an anomalous seismic reflector which coincides with the predicted transition boundary at the base of the gas hydrate zone. Direct evidence of gas hydrates is provided by visual observations of sediments from the landward wall of the Mid-America Trench off Mexico and Guatemala, from the Blake Outer Ridge off the southeastern United States, and from the Black Sea in the U.S.S.R. Where solid gas hydrates have been sampled, the gas is composed mainly of methane accompanied by CO2 and low concentrations of ethane and hydrocarbons of higher molecular weight. The molecular and isotopic composition of hydrocarbons indicates that most of the methane is of biolog cal origin. The gas was probably produced by the bacterial alteration of organic matter buried in the sediment. Organic carbon contents of the sediment containing sampled gas hydrates are higher than the average organic carbon content of marine sediments. The main economic importance of gas hydrates may reside in their ability to serve as a cap under which free gas can collect. To be producible, however, such trapped gas must occur in porous and permeable reservoirs. Although gas hydrates are common along continental margins, the degree to which they are associated with significant reservoirs remains to be investigated.

  6. Determination of hydration film thickness using atomic force microscopy

    Institute of Scientific and Technical Information of China (English)

    PENG Changsheng; SONG Shaoxian; GU Qingbao

    2005-01-01

    Dispersion of a solid particle in water may lead to the formation of hydration film on the particle surface, which can strongly increase the repulsive force between the particles and thus strongly affect the stability of dispersions. The hydration film thickness, which varies with the variation of property of suspension particles, is one of the most important parameters of hydration film, and is also one of the most difficult parameters that can be measured accurately. In this paper, a method, based on force-distance curve of atomic force microscopy, for determining the hydration film thickness of particles is developed. The method utilizes the difference of cantilever deflection before, between and after penetrating the hydration films between tip and sample, which reflect the difference of slope on the force-distance curve. 3 samples, mica, glass and stainless steel, were used for hydration thickness determination, and the results show that the hydration film thickness between silicon tip and mica, glass and stainless steel are 30.0(2.0, 29.0(1.0 and 32.5(2.5 nm, respectively.

  7. Hydration status of pregnant women in West Jakarta.

    Science.gov (United States)

    Mulyani, Erry Yudhya; Hardinsyah; Briawan, Dodik; Santoso, Budi Iman

    2017-06-01

    During pregnancy, the body exhibits dynamic changes in fluid composition. More than 50%of women experience nausea and vomiting during the first trimester. Studies of hydration status in pregnant women are limited, and not in tropical countries, like in Indonesia. The objective of this study was to investigate the hydration status and appropriate biomarkers for determination of hydration status in pregnant women in West Jakarta. This study was cross-sectional. A total of 35 pregnant women aged (19-35 years) at the early second trimester of pregnancy was recruited. Urine osmolality, urine specific gravity, and serum osmolality were used to determine hydration status. Subjects then were divided into a hydration group (HG) and a dehydration group (DG). We used independent t tests, chi-square and Spearman rank correlation coefficient to analyse the data. The population was comparably divided between dehydration and hydration groups (57.1% and 42.9%, respectively). The proportions by age, parity, gestational age, height, weight, upper arm circumference, waist circumference, pelvic circumference, body temperature, blood pressure, and fundal height did not differ between groups (p>=0.05). There was a relationship between urine colour and hydration status (ppregnant women.

  8. NIST Gas Hydrate Research Database and Web Dissemination Channel.

    Science.gov (United States)

    Kroenlein, K; Muzny, C D; Kazakov, A; Diky, V V; Chirico, R D; Frenkel, M; Sloan, E D

    2010-01-01

    To facilitate advances in application of technologies pertaining to gas hydrates, a freely available data resource containing experimentally derived information about those materials was developed. This work was performed by the Thermodynamic Research Center (TRC) paralleling a highly successful database of thermodynamic and transport properties of molecular pure compounds and their mixtures. Population of the gas-hydrates database required development of guided data capture (GDC) software designed to convert experimental data and metadata into a well organized electronic format, as well as a relational database schema to accommodate all types of numerical and metadata within the scope of the project. To guarantee utility for the broad gas hydrate research community, TRC worked closely with the Committee on Data for Science and Technology (CODATA) task group for Data on Natural Gas Hydrates, an international data sharing effort, in developing a gas hydrate markup language (GHML). The fruits of these efforts are disseminated through the NIST Sandard Reference Data Program [1] as the Clathrate Hydrate Physical Property Database (SRD #156). A web-based interface for this database, as well as scientific results from the Mallik 2002 Gas Hydrate Production Research Well Program [2], is deployed at http://gashydrates.nist.gov.

  9. X Inactivation and Progenitor Cancer Cells

    Directory of Open Access Journals (Sweden)

    Ruben Agrelo

    2011-04-01

    Full Text Available In mammals, silencing of one of the two X chromosomes is necessary to achieve dosage compensation. The 17 kb non-coding RNA called Xist triggers X inactivation. Gene silencing by Xist can only be achieved in certain contexts such as in cells of the early embryo and in certain hematopoietic progenitors where silencing factors are present. Moreover, these epigenetic contexts are maintained in cancer progenitors in which SATB1 has been identified as a factor related to Xist-mediated chromosome silencing.

  10. Scanning electron microscopy investigations of laboratory-grown gas clathrate hydrates formed from melting ice, and comparison to natural hydrates

    Science.gov (United States)

    Stern, L.A.; Kirby, S.H.; Circone, S.; Durham, W.B.

    2004-01-01

    Scanning electron microscopy (SEM) was used to investigate grain texture and pore structure development within various compositions of pure sI and sII gas hydrates synthesized in the laboratory, as well as in natural samples retrieved from marine (Gulf of Mexico) and permafrost (NW Canada) settings. Several samples of methane hydrate were also quenched after various extents of partial reaction for assessment of mid-synthesis textural progression. All laboratory-synthesized hydrates were grown under relatively high-temperature and high-pressure conditions from rounded ice grains with geometrically simple pore shapes, yet all resulting samples displayed extensive recrystallization with complex pore geometry. Growth fronts of mesoporous methane hydrate advancing into dense ice reactant were prevalent in those samples quenched after limited reaction below and at the ice point. As temperatures transgress the ice point, grain surfaces continue to develop a discrete "rind" of hydrate, typically 5 to 30 ??m thick. The cores then commonly melt, with rind microfracturing allowing migration of the melt to adjacent grain boundaries where it also forms hydrate. As the reaction continues under progressively warmer conditions, the hydrate product anneals to form dense and relatively pore-free regions of hydrate grains, in which grain size is typically several tens of micrometers. The prevalence of hollow, spheroidal shells of hydrate, coupled with extensive redistribution of reactant and product phases throughout reaction, implies that a diffusion-controlled shrinking-core model is an inappropriate description of sustained hydrate growth from melting ice. Completion of reaction at peak synthesis conditions then produces exceptional faceting and euhedral crystal growth along exposed pore walls. Further recrystallization or regrowth can then accompany even short-term exposure of synthetic hydrates to natural ocean-floor conditions, such that the final textures may closely mimic

  11. CO2 hydrate: Synthesis, composition, structure, dissociation behavior, and a comparison to structure I CH4 hydrate

    Science.gov (United States)

    Circone, S.; Stern, L.A.; Kirby, S.H.; Durham, W.B.; Chakoumakos, B.C.; Rawn, C.J.; Rondinone, A.J.; Ishii, Y.

    2003-01-01

    Structure I (sI) carbon dioxide (CO2) hydrate exhibits markedly different dissociation behavior from sI methane (CH4) hydrate in experiments in which equilibrated samples at 0.1 MPa are heated isobarically at 13 K/h from 210 K through the H2O melting point (273.15 K). The CO2 hydrate samples release only about 3% of their gas content up to temperatures of 240 K, which is 22 K above the hydrate phase boundary. Up to 20% is released by 270 K, and the remaining CO2 is released at 271.0 plusmn; 0.5 K, where the sample temperature is buffered until hydrate dissociation ceases. This reproducible buffering temperature for the dissociation reaction CO2??nH2O = CO2(g) + nH2O(1 to s) is measurably distinct from the pure H2O melting point at 273.15 K, which is reached as gas evolution ceases. In contrast, when si CH4 hydrate is heated at the same rate at 0.1 MPa, >95% of the gas is released within 25 K of the equilibrium temperature (193 K at 0.1 MPa). In conjunction with the dissociation study, a method for efficient and reproducible synthesis of pure polycrystalline CO2 hydrate with suitable characteristics for material properties testing was developed, and the material was characterized. CO2 hydrate was synthesized from CO2 liquid and H2O solid and liquid reactants at pressures between 5 and 25 MPa and temperatures between 250 and 281 K. Scanning electron microscopy (SEM) examination indicates that the samples consist of dense crystalline hydrate and 50-300 ??m diameter pores that are lined with euhedral cubic hydrate crystals. Deuterated hydrate samples made by this same procedure were analyzed by neutron diffraction at temperatures between 4 and 215 K; results confirm that complete conversion of water to hydrate has occurred and that the measured unit cell parameter and thermal expansion are consistent with previously reported values. On the basis of measured weight gain after synthesis and gas yields from the dissociation experiments, approximately all cages in the

  12. Electronically Induced Phase Transformations

    Science.gov (United States)

    1980-12-01

    ries (w hen the Slater free-electron exchange is used). A systematic the active researcher. study of relativistic electron densities and isomer...comp:wrees aux mesures actuelles d’effet dHvA d’Arko et Schirber. Le calu; du facteur de forme neutronique en presence d’un champ magnetique est en bon

  13. Inactivation of virus in solution by cold atmospheric pressure plasma: identification of chemical inactivation pathways

    Science.gov (United States)

    Aboubakr, Hamada A.; Gangal, Urvashi; Youssef, Mohammed M.; Goyal, Sagar M.; Bruggeman, Peter J.

    2016-05-01

    Cold atmospheric pressure plasma (CAP) inactivates bacteria and virus through in situ production of reactive oxygen and nitrogen species (RONS). While the bactericidal and virucidal efficiency of plasmas is well established, there is limited knowledge about the chemistry leading to the pathogen inactivation. This article describes a chemical analysis of the CAP reactive chemistry involved in the inactivation of feline calicivirus. We used a remote radio frequency CAP produced in varying gas mixtures leading to different plasma-induced chemistries. A study of the effects of selected scavengers complemented with positive control measurements of relevant RONS reveal two distinctive pathways based on singlet oxygen and peroxynitrous acid. The first mechanism is favored in the presence of oxygen and the second in the presence of air when a significant pH reduction is induced in the solution by the plasma. Additionally, smaller effects of the H2O2, O3 and \\text{NO}2- produced were also found. Identification of singlet oxygen-mediated 2-imidazolone/2-oxo-His (His  +14 Da)—an oxidative modification of His 262 comprising the capsid protein of feline calicivirus links the plasma induced singlet oxygen chemistry to viral inactivation.

  14. Modeling the pressure inactivation dynamics of Escherichia coli

    Directory of Open Access Journals (Sweden)

    Yamamoto K.

    2005-01-01

    Full Text Available Escherichia coli, as a model microorganism, was treated in phosphate-buffered saline under high hydrostatic pressure between 100 and 300 MPa, and the inactivation dynamics was investigated from the viewpoint of predictive microbiology. Inactivation data were curve fitted by typical predictive models: logistic, Gompertz and Weibull functions. Weibull function described the inactivation curve the best. Two parameters of Weibull function were calculated for each holding pressure and their dependence on holding pressure was obtained by interpolation. With the interpolated parameters, inactivation curves were simulated and compared with the experimental data sets.

  15. The effect of polymethylsiloxanes on hydration of clinker phases

    Science.gov (United States)

    Stoch, A.; Zdaniewicz, M.; Paluszkiewicz, Cz.

    1999-11-01

    The effect of the polydimethylsiloxane (PDMS) admixture on hydration of pure clinker phases: alite, belite or tricalcium aluminate was studied by means of FTIR spectroscopy. It was shown that PDMS, introduced to a clinker phase paste during the hydration process reduces the carbonation reaction, improves the crystallization of hydrates in tricalcium aluminate and considerably increases water resistance without significantly changing the mechanical parameters. Our FTIR results were also confirmed by XRD, DTA and SEM study of the morphology of the newly formed phases. Introduction of as much as 5 wt.% of the PDMS increases the wetting angle by up to 80-120°.

  16. Gas hydrate dissociation prolongs acidification of the Anthropocene oceans

    OpenAIRE

    Boudreau, B.P.; Luo, Yiming; Filip J R Meysman; J. J. Middelburg; G. R. Dickens

    2015-01-01

    Anthropogenic warming of the oceans can release methane (CH4) currently stored in sediments as gas hydrates. This CH4 will be oxidized to CO2, thus increasing the acidification of the oceans. We employ a biogeochemical model of the multimillennial carbon cycle to determine the evolution of the oceanic dissolved carbonate system over the next 13 kyr in response to CO2 from gas hydrates, combined with a reasonable scenario for long-term anthropogenic CO2 emissions. Hydrate-derived CO2 will appr...

  17. Effect on Hydration and Hardening of Tricalcium Phosphate Bone Cement

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The bioactive α-Ca3 (PO4)2 bone cement was studied by XRD , SEM and isothermal calorimetric measurements. The results showed that a mixed pattern of TCP and hydroxylapatite were obtained after hydration and hardening. The mechanism of hydration and hardening of the α-Ca3 ( PO4 )2 was dissolution-precipitation,(NH4) H2 PO4 was the best set accelerator to the α-Ca3 ( PO4 )2 cement, and the HAP powers and the(NH4) H2 PO4 concentration had a great effect on the hydration rate of α-Ca3 ( PO4 )2.

  18. Examination of Hydrate Formation Methods: Trying to Create Representative Samples

    Energy Technology Data Exchange (ETDEWEB)

    Kneafsey, T.J.; Rees, E.V.L.; Nakagawa, S.; Kwon, T.-H.

    2011-04-01

    Forming representative gas hydrate-bearing laboratory samples is important so that the properties of these materials may be measured, while controlling the composition and other variables. Natural samples are rare, and have often experienced pressure and temperature changes that may affect the property to be measured [Waite et al., 2008]. Forming methane hydrate samples in the laboratory has been done a number of ways, each having advantages and disadvantages. The ice-to-hydrate method [Stern et al., 1996], contacts melting ice with methane at the appropriate pressure to form hydrate. The hydrate can then be crushed and mixed with mineral grains under controlled conditions, and then compacted to create laboratory samples of methane hydrate in a mineral medium. The hydrate in these samples will be part of the load-bearing frame of the medium. In the excess gas method [Handa and Stupin, 1992], water is distributed throughout a mineral medium (e.g. packed moist sand, drained sand, moistened silica gel, other porous media) and the mixture is brought to hydrate-stable conditions (chilled and pressurized with gas), allowing hydrate to form. This method typically produces grain-cementing hydrate from pendular water in sand [Waite et al., 2004]. In the dissolved gas method [Tohidi et al., 2002], water with sufficient dissolved guest molecules is brought to hydrate-stable conditions where hydrate forms. In the laboratory, this is can be done by pre-dissolving the gas of interest in water and then introducing it to the sample under the appropriate conditions. With this method, it is easier to form hydrate from more soluble gases such as carbon dioxide. It is thought that this method more closely simulates the way most natural gas hydrate has formed. Laboratory implementation, however, is difficult, and sample formation is prohibitively time consuming [Minagawa et al., 2005; Spangenberg and Kulenkampff, 2005]. In another version of this technique, a specified quantity of gas

  19. Experimental studies for the cyclability of salt hydrates for thermochemical heat storage

    NARCIS (Netherlands)

    Donkers, P.A.J.; Pel, L.; Adan, O.C.G.

    2016-01-01

    Salt hydrates have promising potential as heat storage materials by use of their hydration/dehydration reaction. These hydration/dehydration reactions are studied in this paper for CuCl2, CuSO4, MgCl2 and MgSO4. During a hydration/dehydration reaction, the salt shrinks and expands as a result of the

  20. Protection against Japanese encephalitis by inactivated vaccines.

    Science.gov (United States)

    Hoke, C H; Nisalak, A; Sangawhipa, N; Jatanasen, S; Laorakapongse, T; Innis, B L; Kotchasenee, S; Gingrich, J B; Latendresse, J; Fukai, K

    1988-09-01

    Encephalitis caused by Japanese encephalitis virus occurs in annual epidemics throughout Asia, making it the principal cause of epidemic viral encephalitis in the world. No currently available vaccine has demonstrated efficacy in preventing this disease in a controlled trial. We performed a placebo-controlled, blinded, randomized trial in a northern Thai province, with two doses of monovalent (Nakayama strain) or bivalent (Nakayama plus Beijing strains) inactivated, purified Japanese encephalitis vaccine made from whole virus derived from mouse brain. We examined the effect of these vaccines on the incidence and severity of Japanese encephalitis and dengue hemorrhagic fever, a disease caused by a closely related flavivirus. Between November 1984 and March 1985, 65,224 children received two doses of monovalent Japanese encephalitis vaccine (n = 21,628), bivalent Japanese encephalitis vaccine (n = 22,080), or tetanus toxoid placebo (n = 21,516), with only minor side effects. The cumulative attack rate for encephalitis due to Japanese encephalitis virus was 51 per 100,000 in the placebo group and 5 per 100,000 in each vaccine group. The efficacy in both vaccine groups combined was 91 percent (95 percent confidence interval, 70 to 97 percent). Attack rates for dengue hemorrhagic fever declined, but not significantly. The severity of cases of dengue was also reduced. We conclude that two doses of inactivated Japanese encephalitis vaccine, either monovalent or bivalent, protect against encephalitis due to Japanese encephalitis virus and may have a limited beneficial effect on the severity of dengue hemorrhagic fever.

  1. FEF inactivation with improved optogenetic methods.

    Science.gov (United States)

    Acker, Leah; Pino, Erica N; Boyden, Edward S; Desimone, Robert

    2016-11-15

    Optogenetic methods have been highly effective for suppressing neural activity and modulating behavior in rodents, but effects have been much smaller in primates, which have much larger brains. Here, we present a suite of technologies to use optogenetics effectively in primates and apply these tools to a classic question in oculomotor control. First, we measured light absorption and heat propagation in vivo, optimized the conditions for using the red-light-shifted halorhodopsin Jaws in primates, and developed a large-volume illuminator to maximize light delivery with minimal heating and tissue displacement. Together, these advances allowed for nearly universal neuronal inactivation across more than 10 mm(3) of the cortex. Using these tools, we demonstrated large behavioral changes (i.e., up to several fold increases in error rate) with relatively low light power densities (≤100 mW/mm(2)) in the frontal eye field (FEF). Pharmacological inactivation studies have shown that the FEF is critical for executing saccades to remembered locations. FEF neurons increase their firing rate during the three epochs of the memory-guided saccade task: visual stimulus presentation, the delay interval, and motor preparation. It is unclear from earlier work, however, whether FEF activity during each epoch is necessary for memory-guided saccade execution. By harnessing the temporal specificity of optogenetics, we found that FEF contributes to memory-guided eye movements during every epoch of the memory-guided saccade task (the visual, delay, and motor periods).

  2. Ribosome Inactivating Proteins from Plants Inhibiting Viruses

    Institute of Scientific and Technical Information of China (English)

    Inderdeep Kaur; R C Gupta; Munish Puri

    2011-01-01

    Many plants contain ribosome inactivating proteins (RIPs) with N-glycosidase activity,which depurinate large ribosomal RNA and arrest protein synthesis.RIPs so far tested inhibit replication of mRNA as well as DNA viruses and these proteins,isolated from plants,are found to be effective against a broad range of viruses such as human immunodeficiency virus (HIV),hepatitis B virus (HBV) and herpes simplex virus (HSV).Most of the research work related to RIPs has been focused on antiviral activity against HIV; however,the exact mechanism of antiviral activity is still not clear.The mechanism of antiviral activity was thought to follow inactivation of the host cell ribosome,leading to inhibition of viral protein translation and host cell death.Enzymatic activity of RIPs is not hmited to depurination of the large rRNA,in addition they can depurinate viral DNA as well as RNA.Recently,Phase Ⅰ/Ⅱ clinical trials have demonstrated the potential use of RIPs for treating patients with HIV disease.The aim of this review is to focus on various RIPs from plants associated with anti-HIV activity.

  3. Formation of natural gas hydrates in marine sediments 1. Conceptual model of gas hydrate growth conditioned by host sediment properties

    Science.gov (United States)

    Clennell, M.B.; Hovland, M.; Booth, J.S.; Henry, P.; Winters, W.J.

    1999-01-01

    The stability of submarine gas hydrates is largely dictated by pressure and temperature, gas composition, and pore water salinity. However, the physical properties and surface chemistry of deep marine sediments may also affect the thermodynamic state, growth kinetics, spatial distributions, and growth forms of clathrates. Our conceptual model presumes that gas hydrate behaves in a way analogous to ice in a freezing soil. Hydrate growth is inhibited within fine-grained sediments by a combination of reduced pore water activity in the vicinity of hydrophilic mineral surfaces, and the excess internal energy of small crystals confined in pores. The excess energy can be thought of as a "capillary pressure" in the hydrate crystal, related to the pore size distribution and the state of stress in the sediment framework. The base of gas hydrate stability in a sequence of fine sediments is predicted by our model to occur at a lower temperature (nearer to the seabed) than would be calculated from bulk thermodynamic equilibrium. Capillary effects or a build up of salt in the system can expand the phase boundary between hydrate and free gas into a divariant field extending over a finite depth range dictated by total methane content and pore-size distribution. Hysteresis between the temperatures of crystallization and dissociation of the clathrate is also predicted. Growth forms commonly observed in hydrate samples recovered from marine sediments (nodules, and lenses in muds; cements in sands) can largely be explained by capillary effects, but kinetics of nucleation and growth are also important. The formation of concentrated gas hydrates in a partially closed system with respect to material transport, or where gas can flush through the system, may lead to water depletion in the host sediment. This "freeze-drying" may be detectable through physical changes to the sediment (low water content and overconsolidation) and/or chemical anomalies in the pore waters and metastable

  4. Relation between relative permeability and hydrate saturation in Shenhu area, South China Sea

    Institute of Scientific and Technical Information of China (English)

    Li Chuan-Hui; Zhao Qian; Xu Hong-Jun; Feng Kai; Liu Xue-Wei

    2014-01-01

    Nuclear magnetic resonance measurements in hydrate-bearing sandstone samples from the Shenhu area, South China Sea were used to study the effect of gas hydrates on the sandstone permeability. The hydrate-bearing samples contain pore-fi lling hydrates. The data show that the pore-fi lling hydrates greatly affect the formation permeability while depending on many factors that also bear on permeability; furthermore, with increasing hydrate saturation, the formation permeability decreases. We used the Masuda model and an exponent N = 7.9718 to formulate the empirical equation that describes the relation between relative permeability and hydrate saturation for the Shenhu area samples.

  5. The assessment of efficacy of porcine reproductive respiratory syndrome virus inactivated vaccine based on the viral quantity and inactivation methods

    National Research Council Canada - National Science Library

    Kim, Hyunil; Kim, Hye Kwon; Jung, Jung Ho; Choi, Yoo Jung; Kim, Jiho; Um, Chang Gyu; Hyun, Su Bin; Shin, Sungho; Lee, Byeongchun; Jang, Goo; Kang, Bo Kyu; Moon, Hyoung Joon; Song, Dae Sub

    2011-01-01

    ...). Although inactivated PRRSV vaccines are preferred for their safety, they are weak at inducing humoral immune responses and controlling field PRRSV infection, especially when heterologous viruses are involved...

  6. Energy from gas hydrates - assessing the opportunities and challenges for Canada: report of the expert panel on gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-09-15

    Gas hydrates form when water and natural gas combine at low temperatures and high pressures in regions of permafrost and in marine subseafloor sediments. Estimates suggest that the total amount of natural gas bound in hydrate form may exceed all conventional gas resources, or even the amount of all combined hydrocarbon energy. Gas from gas hydrate could provide a potentially vast new source of energy to offset declining supplies of conventional natural gas in North America and to provide greater energy security for countries such as Japan and India that have limited domestic sources. However, complex issues would need to be addressed if gas hydrate were to become a large part of the energy future of Canada. Natural Resources Canada asked the Council of Canadian Academies to assemble a panel of experts to examine the challenges for an acceptable operational extraction of gas hydrates in Canada. This report presented an overview of relevant contextual background, including some basic science; the medium-term outlook for supply and demand in markets for natural gas; broad environmental issues related to gas hydrate in its natural state and as a fuel; and an overview of Canada's contribution to knowledge about gas hydrate in the context of ongoing international research activity. The report also presented current information on the subject and what would be required to delineate and quantify the resource. Techniques for extracting gas from gas hydrate were also outlined. The report also addressed safety issues related to gas hydrate dissociation during drilling operations or release into the atmosphere; the environmental issues associated with potential leakage of methane into the atmosphere and with the large volumes of water produced during gas hydrate dissociation; and jurisdictional and local community issues that would need to be resolved in order to proceed with the commercial exploitation of gas hydrate. It was concluded that there does not appear to be

  7. Fragmentation of Singly, Doubly, and Triply Charged Hydrogen Deficient Peptide Radical Cations in Infrared Multiphoton Dissociation and Electron Induced Dissociation

    Science.gov (United States)

    Kalli, Anastasia; Hess, Sonja

    2012-02-01

    Gas phase fragmentation of hydrogen deficient peptide radical cations continues to be an active area of research. While collision induced dissociation (CID) of singly charged species is widely examined, dissociation channels of singly and multiply charged radical cations in infrared multiphoton dissociation (IRMPD) and electron induced dissociation (EID) have not been, so far, investigated. Here, we report on the gas phase dissociation of singly, doubly and triply charged hydrogen deficient peptide radicals, [M + nH](n+1)+· ( n = 0, 1, 2), in MS3 IRMPD and EID and compare the observed fragmentation pathways to those obtained in MS3 CID. Backbone fragmentation in MS3 IRMPD and EID was highly dependent on the charge state of the radical precursor ions, whereas amino acid side chain cleavages were largely independent of the charge state selected for fragmentation. Cleavages at aromatic amino acids, either through side chain loss or backbone fragmentation, were significantly enhanced over other dissociation channels. For singly charged species, the MS3 IRMPD and EID spectra were mainly governed by radical-driven dissociation. Fragmentation of doubly and triply charged radical cations proceeded through both radical- and charge-driven processes, resulting in the formation of a wide range of backbone product ions including, a-, b-, c-, y-, x-, and z-type. While similarities existed between MS3 CID, IRMPD, and EID of the same species, several backbone product ions and side chain losses were unique for each activation method. Furthermore, dominant dissociation pathways in each spectrum were dependent on ion activation method, amino acid composition, and charge state selected for fragmentation.

  8. Early hydration cement Effect of admixtures superplasticizers

    Directory of Open Access Journals (Sweden)

    Puertas, F.

    2001-06-01

    Full Text Available Early hydration of portland cement with superplasticizer admixtures of different nature has been studied. These admixtures were: one based on melamine synthetic, other based on vinyl copolymer and other based on polyacrylate copolymers. The dosage of the formers were constant (1% weigth of cement and for the third, the influence of admixture dosage was also evaluated, giving dosage values among 1-0.3%. The pastes obtained were studied by conduction calorimetry, XRD and FTIR. Also the apparent fluidity was determined by "Minislump" test. The main results obtained were: a superplasticizers admixtures used, regardless of their nature and for the polycarboxilate one the dosage, retard the silicate hydration (specially, alite phase, b The ettringite formation is affected by the nature of the admixture. cA relationship between the dosage of admixture based on polycarboxilates and the time at the acceleration has been established. A lineal relation (y = 11.03 + 16.05x was obtained. From these results is possible to know, in function of dosage admixture, the time when the masive hydration products and the setting times are produced. Also the total heat releases in these reactions is independent of the nature and dosage of admixture, saying that in all cases the reactions are the same.

    En el presente trabajo se ha estudiado la hidratación inicial de un cemento portland aditivado con superplastificantes de diferente naturaleza. Dichos aditivos fueron: uno basado en melaminas sintéticas, otro en copolímeros vinilicos y otro en policarboxilatos. La dosificación de los dos primeros se fijó constante en 1% en peso con relación al cemento, mientras que para el tercero se evaluó, también, la influencia de la dosificación, tomando proporciones desde el 1% hasta el 0,3%. Las pastas obtenidas se estudiaron por: calorimetría de conducción, DRX y FTIR. También se determinó la fluidez de la pasta a través del ensayo del "Minislump ". Los

  9. Low-δD hydration rinds in Yellowstone perlites record rapid syneruptive hydration during glacial and interglacial conditions

    Science.gov (United States)

    Bindeman, Ilya N.; Lowenstern, Jacob B.

    2016-01-01

    Hydration of silicic volcanic glass forms perlite, a dusky, porous form of altered glass characterized by abundant “onion-skin” fractures. The timing and temperature of perlite formation are enigmatic and could plausibly occur during eruption, during post-eruptive cooling, or much later at ambient temperatures. To learn more about the origin of natural perlite, and to fingerprint the hydration waters, we investigated perlitic glass from several synglacial and interglacial rhyolitic lavas and tuffs from the Yellowstone volcanic system. Perlitic cores are surrounded by a series of conchoidal cracks that separate 30- to 100-µm-thick slivers, likely formed in response to hydration-induced stress. H2O and D/H profiles confirm that most D/H exchange happens together with rapid H2O addition but some smoother D/H variations may suggest separate minor exchange by deuterium atom interdiffusion following hydration. The hydrated rinds (2–3 wt% H2O) transition rapidly (within 30 µm, or by 1 wt% H2O per 10 µm) to unhydrated glass cores. This is consistent with quenched “hydration fronts” where H2O diffusion coefficients are strongly dependent on H2O concentrations. The chemical, δ18O, and δD systematics of bulk glass records last equilibrium between ~110 and 60 °C without chemical exchange but with some δ18O exchange. Similarly, the δ18O of water extracted from glass by rapid heating suggests that water was added to the glass during cooling at C. Our observations support fast hydration at temperatures as low as 60 °C; prolonged exposure to high temperature of 175°–225° during water addition is less likely as the glass would lose alkalies and should alter to clays within days. A compilation of low-temperature hydration diffusion coefficients suggests ~2 orders of magnitude higher rates of diffusion at 60–110 °C temperatures, compared with values expected from extrapolation of high-temperature (>400 °C) experimental data. The thick hydration

  10. Influence of Cellulose Ethers on Hydration Products of Portland Cement

    Institute of Scientific and Technical Information of China (English)

    MA Baoguo; OU Zhihua; JIAN Shouwei; XU Rulin

    2011-01-01

    Cellulose ethers are widely used to mortar formulations, and it is significant to understand the interaction between cellulose ethers and cement pastes. FT-IR spectra, thermal analysis and SEM are used to investigate hydration products in the cement pastes modified by HEMC and HPMC in this article. The results show that the hydration products in modified cement pastes were finally identical with those in the unmodified cement paste, but the major hydration products, such as CH (calcium hydroxide), ettringite and C-S-H, appeared later in the modified cement pastes than in the unmodified cement paste. The cellulose ethers decrease the outer products and increase inner products of C-S-H gels. Compared to unmodified cement pastes, no new products are found in the modified cement pastes in the present experiment. The HEMC and HPMC investigation shows almost the same influence on the hydration products of Portland cement.

  11. Geo-scientific investigations of gas-hydrates in India

    Digital Repository Service at National Institute of Oceanography (India)

    Sain, K.; Gupta, H.; Mazumdar, A.; Bhaumik, A.K.; Bhowmick, P.K.

    The best solution to meet India's overwhelming energy requirement is to tap the nuclear and solar power to the maximum extent possible. Another feasible major energy resource is gas-hydrates (crystalline substances of methane and water) that have...

  12. Methods of gas hydrate concentration estimation with field examples

    Digital Repository Service at National Institute of Oceanography (India)

    Kumar, D.; Dash, R.; Dewangan, P.

    different methods of gas hydrate concentration estimation that make use of data from the measurements of the seismic properties, electrical resistivity, chlorinity, porosity, density, and temperature are summarized in this paper. We demonstrate the methods...

  13. Application of various water soluble polymers in gas hydrate inhibition

    DEFF Research Database (Denmark)

    Kamal, Muhammad Shahzad; Hussein, Ibnelwaleed A.; Sultan, Abdullah S.

    2016-01-01

    . This review presents the various types of water soluble polymers used for hydrate inhibition, including conventional and novel polymeric inhibitors along with their limitations. The review covers the relevant properties of vinyl lactam, amide, dendrimeric, fluorinated, and natural biodegradable polymers...

  14. Infrared spectroscopy for monitoring gas hydrates in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Dobbs, G.T.; Luzinova, Y.; Mizaikoff, B. [Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemistry and Biochemistry; Raichlin, Y.; Katzir, A. [Tel-Aviv Univ., Tel-Aviv (Israel). Shool of Physics and Astronomy

    2008-07-01

    This paper introduced the first principles for monitoring gas hydrate formation and dissociation in aqueous solution by evaluating state-responsive infrared (IR) absorption features of water with fiberoptic evanescent field spectroscopy. A first order linear functional relationship was also derived according to Lambert Beer's law in order to quantify the percentage gas hydrate within the volume of water probed via the evanescent field. In addition, spectroscopic studies evaluating seafloor sediments collected from a gas hydrate site in the Gulf of Mexico revealed minimal spectral interferences from sediment matrix components. As such, evanescent field sensing strategies were established as a promising perspective for monitoring the dynamics of gas hydrates in oceanic environments. 21 refs., 5 figs.

  15. Methane Hydrates: More Than a Viable Aviation Fuel Feedstock Option

    Science.gov (United States)

    Hendricks, Robert C.

    2007-01-01

    Demand for hydrocarbon fuels is steadily increasing, and greenhouse gas emissions continue to rise unabated with the energy demand. Alternate fuels will be coming on line to meet that demand. This report examines the recovering of methane from methane hydrates for fuel to meet this demand rather than permitting its natural release into the environment, which will be detrimental to the planet. Some background on the nature, vast sizes, and stability of sedimentary and permafrost formations of hydrates are discussed. A few examples of the severe problems associated with methane recovery from these hydrates are presented along with the potential impact on the environment and coastal waters. Future availability of methane from hydrates may become an attractive option for aviation fueling, and so future aircraft design associated with methane fueling is considered.

  16. The hydration/dehydration behavior of aspartame revisited.

    Science.gov (United States)

    Guguta, C; Meekes, H; de Gelder, R

    2008-03-13

    Aspartame, l-aspartyl-l-phenylalanine methyl ester, has two hydrates (IA and IB), a hemi-hydrate (IIA) and an anhydrate (IIB). The hydration/dehydration behavior of aspartame was investigated using hot-humidity stage X-ray powder diffraction (XRPD) and molecular mechanics modeling in combination with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results of this study are compared to earlier studies on aspartame as described in literature. It is shown that earlier transition studies were hampered by incomplete conversions and wrong assignment of the forms. The combination of the techniques applied in this study now shows consistent results for aspartame and yields a clear conversion scheme for the hydration/dehydration behavior of the four forms.

  17. Gas hydrate detection and mapping on the US east coast

    Energy Technology Data Exchange (ETDEWEB)

    Ahlbrandt, T.S.; Dillon, W.P.

    1993-12-31

    Project objectives are to identify and map gas hydrate accumulations on the US eastern continental margin using remote sensing (seismic profiling) techniques and to relate these concentrations to the geological factors that-control them. In order to test the remote sensing methods, gas hydrate-cemented sediments will be tested in the laboratory and an effort will be made to perform similar physical tests on natural hydrate-cemented sediments from the study area. Gas hydrate potentially may represent a future major resource of energy. Furthermore, it may influence climate change because it forms a large reservoir for methane, which is a very effective greenhouse gas; its breakdown probably is a controlling factor for sea-floor landslides; and its presence has significant effect on the acoustic velocity of sea-floor sediments.

  18. Critical state soil constitutive model for methane hydrate soil

    National Research Council Canada - National Science Library

    S. Uchida; K. Soga; K. Yamamoto

    2012-01-01

      This paper presents a new constitutive model that simulates the mechanical behavior of methane hydrate-bearing soil based on the concept of critical state soil mechanics, referred to as the Methane...

  19. Perspective: Structure and ultrafast dynamics of biomolecular hydration shells

    Directory of Open Access Journals (Sweden)

    Damien Laage

    2017-07-01

    Full Text Available The structure and function of biomolecules can be strongly influenced by their hydration shells. A key challenge is thus to determine the extent to which these shells differ from bulk water, since the structural fluctuations and molecular excitations of hydrating water molecules within these shells can cover a broad range in both space and time. Recent progress in theory, molecular dynamics simulations, and ultrafast vibrational spectroscopy has led to new and detailed insight into the fluctuations of water structure, elementary water motions, and electric fields at hydrated biointerfaces. Here, we discuss some central aspects of these advances, focusing on elementary molecular mechanisms and processes of hydration on a femto- to picosecond time scale, with some special attention given to several issues subject to debate.

  20. The Hydrated Electron -- Jekyll And Hyde In A Test Tube

    Science.gov (United States)

    Robinson, G. W.; Hameka, H. F.

    1987-01-01

    Experimental evidence pertaining to the structure of the hydrated electron is reviewed. In agreement with recent picosecond optoelectronic data, it is concluded that at low or moderate temperatures the hydrated electron is not an electron at all! Rather, it is very likely a hydrated semi-ionic pair (OH...H30)(aq), having the chemical properties of either OH-(aq) or H(aq). However, under certain conditions, where the hydrogen-bond structure of the solvent is weak, the hydrated electron may delocalize somewhat into the surrounding water medium.to become "its old self", behaving more like an electron in a cavity. This fragmented personality of one of chemistry's most celebrated fundamental particles is further substantiated by ab initio quantum mechanical calculations.

  1. Evaluation of Heat Induced Methane Release from Methane Hydrates

    Science.gov (United States)

    Leeman, J.; Elwood-Madden, M.; Phelps, T. J.; Rawn, C. J.

    2010-12-01

    Clathrates, or gas hydrates, structurally are guest gas molecules populating a cavity in a cage of water molecules. Gas hydrates naturally occur on Earth under low temperature and moderate pressure environments including continental shelf, deep ocean, and permafrost sediments. Large quantities of methane are trapped in hydrates, providing significant near-surface reserves of carbon and energy. Thermodynamics predicts that hydrate deposits may be destabilized by reducing the pressure in the system or raising the temperature. However, the rate of methane release due to varying environmental conditions remains relatively unconstrained and complicated by natural feedback effects of clathrate dissociation. In this study, hydrate dissociation in sediment due to localized increases in temperature was monitored and observed at the mesoscale (>20L) in a laboratory environment. Experiments were conducted in the Seafloor Process Simulator (SPS) at Oak Ridge National Laboratory (ORNL) to simulate heat induced dissociation. The SPS, containing a column of Ottawa sand saturated with water containing 25mg/L Sno-Max to aid nucleation, was pressurized and cooled well into the hydrate stability field. A fiber optic distributed sensing system (DSS) was embedded at four depths in the sediment column. This allowed the temperature strain value (a proxy for temperature) of the system to be measured with high spatial resolution to monitor the clathrate formation/dissociation processes. A heat exchanger embedded in the sediment was heated using hot recirculated ethylene glycol and the temperature drop across the exchanger was measured. These experiments indicate a significant and sustained amount of heat is required to release methane gas from hydrate-bearing sediments. Heat was consumed by hydrate dissociated in a growing sphere around the heat exchanger until steady state was reached. At steady state all heat energy entering the system was consumed in maintaining the temperature profile

  2. Interaction Study of Guest with Host in Clathrate Hydrate

    Institute of Scientific and Technical Information of China (English)

    Lin Wang; Shunle Dong

    2007-01-01

    Lattice dynamical simulations of noble gas hydrate structures I and II have been performed. Potential energies were investigated to study the influence of guest species on the stability of the hydrate structure. Results show that when the diameter of inclusion molecules is between 3 A and 4.2 A, such as Ar and Kr, the critical role of the 512 cage in the stabilization of hydrates becomes effective. For Xe hydrates SI and SII, with the help of lattice dynamical calculations, the modes attributions are identified directly. We proposed the resonant effect of the fingerprint frequency at about 7 meV and 10 meV which arise from the coupling of Xe molecules in the 512 cage with the host lattice.

  3. Multicomponent seismic forward modeling of gas hydrates beneath the seafloor

    Institute of Scientific and Technical Information of China (English)

    Yang Jia-Jia; He Bing-Shou; Zhang Jian-Zhong

    2014-01-01

    We investigated the effect of microscopic distribution modes of hydrates in porous sediments, and the saturation of hydrates and free gas on the elastic properties of saturated sediments. We simulated the propagation of seismic waves in gas hydrate-bearing sediments beneath the seafloor, and obtained the common receiver gathers of compressional waves (P-waves) and shear waves (S-waves). The numerical results suggest that the interface between sediments containing gas hydrates and free gas produces a large-amplitude bottom-simulating reflector. The analysis of multicomponent common receiver data suggests that ocean-bottom seismometers receive the converted waves of upgoing P-and S-waves, which increases the complexity of the wavefield record.

  4. Clinical study on orofacial photonic hydration using phototherapy and biomaterials

    Science.gov (United States)

    Lizarelli, Rosane F. Z.; Grandi, Natália D. P.; Florez, Fernando L. E.; Grecco, Clovis; Lopes, Luciana A.

    2015-06-01

    Skin hydration is important to prevent aging and dysfunction of orofacial system. Nowadays, it is known that cutaneous system is linked to muscle system, then every dentist need to treat healthy facial skin, as lips, keeping orofacial functions healthy. Thirty-two patients were treated using laser and led therapy single or associated to biomaterials (dermo-cosmetics) searching for the best protocol to promote skin hydration. Using a peace of equipment to measure electric impedance, percentage of water and oil from skin, before and after different treatments were analyzed. Statistic tests using 5% and 0.1% of significance were applied and results showed that light could improve hydration of epidermis layer of facial skin. Considering just light effect, using infrared laser followed by blue led system is more effective to hydration than just blue led system application. Considering dermo-cosmetic and light, the association between both presented the best result.

  5. Methane hydrates and the future of natural gas

    Science.gov (United States)

    Ruppel, Carolyn

    2011-01-01

    For decades, gas hydrates have been discussed as a potential resource, particularly for countries with limited access to conventional hydrocarbons or a strategic interest in establishing alternative, unconventional gas reserves. Methane has never been produced from gas hydrates at a commercial scale and, barring major changes in the economics of natural gas supply and demand, commercial production at a large scale is considered unlikely to commence within the next 15 years. Given the overall uncertainty still associated with gas hydrates as a potential resource, they have not been included in the EPPA model in MITEI’s Future of Natural Gas report. Still, gas hydrates remain a potentially large methane resource and must necessarily be included in any consideration of the natural gas supply beyond two decades from now.

  6. Thermal Stability and Proton Conductivity of Rare Earth Orthophosphate Hydrates

    DEFF Research Database (Denmark)

    Anfimova, Tatiana; Li, Qingfeng; Jensen, Jens Oluf

    2014-01-01

    Hydrated orthophosphate powders of three rare earth metals, lanthanum, neodymium and gadolinium, were prepared and studied as potential proton conducting materials for intermediate temperature electrochemical applications. The phosphates undergo a transformation from the rhabdophane structure...

  7. Simteche Hydrate CO2 Capture Process

    Energy Technology Data Exchange (ETDEWEB)

    Nexant and Los Alamos National Laboratory

    2006-09-30

    As a result of an August 4, 2005 project review meeting held at Los Alamos National Laboratory (LANL) to assess the project's technical progress, Nexant/Simteche/LANL project team was asked to meet four targets related to the existing project efforts. The four targets were to be accomplished by the September 30, 2006. These four targets were: (1) The CO{sub 2} hydrate process needs to show, through engineering and sensitivity analysis, that it can achieve 90% CO{sub 2} capture from the treated syngas stream, operating at 1000 psia. The cost should indicate the potential of achieving the Sequestration Program's cost target of less than 10% increase in the cost of electricity (COE) of the non-CO{sub 2} removal IGCC plant or demonstrate a significant cost reduction from the Selexol process cost developed in the Phase II engineering analysis. (2) The ability to meet the 20% cost share requirement for research level efforts. (3) LANL identifies through equilibrium and bench scale testing a once-through 90% CO{sub 2} capture promoter that supports the potential to achieve the Sequestration Program's cost target. Nexant is to perform an engineering analysis case to verify any economic benefits, as needed; no ETM validation is required, however, for this promoter for FY06. (4) The CO{sub 2} hydrate once-through process is to be validated at 1000 psia with the ETM at a CO{sub 2} capture rate of 60% without H{sub 2}S. The performance of 68% rate of capture is based on a batch, equilibrium data with H{sub 2}S. Validation of the test results is required through multiple runs and engineering calculations. Operational issues will be solved that will specifically effect the validation of the technology. Nexant was given the primary responsibility for Target No.1, while Simteche was mainly responsible for Target No.2; with LANL having the responsibility of Targets No.3 and No.4.

  8. EXPERIMENTAL INVESTIGATION ON GAS HYDRATE FORMATION IN PRESENCE OF ADDITIVE COMPONENTS

    Institute of Scientific and Technical Information of China (English)

    SUN Zhigao; FAN Shuanshi; GUO Kaihua

    2003-01-01

    Additives were used to increase gas hydrate formation rate and storage capacity. Experimental tests of methane hydrate formation were carried out in surfactant water solutions in a high-pressure cell.Sodium dodecyl sulfate (SDS) and alkyl polysaccharide glycoside (APG) were used to increase hydrate formation. The effect of SDS on hydrate formation is more pronounced compared APG. Cyclopentane (CP) also improves hydrate formation rates while it cannot increase methane gas storage capacity.

  9. Hydration Effects on Human Physiology and Exercise-Heat Performance

    Science.gov (United States)

    1989-11-01

    AD REPORT NO T7-90 HYDRATION EFFECTS :N HUMAN PHYSIOLOGY AND EXERCISE-HEA PERFORMANCE Co U S ARMY RESEARCH INSTITUTE N OF I ENVIRONMENTAL MEDICINE...effects on human physiology and exercise.-heat performance 12 PERSONAL AUTHOR(S) Michael N. Sawka, Andrew J. Young. William A. Latzka, P. Darrell...acknowledge Ms. Patricia DeMusis for preparing the manuscript. AD Report No. HYDRATION EFFECTS ON HUMAN PHYSIOLOGY AND EXERCISE-HEAT PERFORMANCE by Michael N

  10. Electrical Measurement to Assess Hydration Process and the Porosity Formation

    Institute of Scientific and Technical Information of China (English)

    WEI Xiaosheng; XIAO Lianzhen; LI Zongjin

    2008-01-01

    The change of electrical resistivity with time at early ages was used to investigate the hydration process and the porosity development. Porosity reduction process of cement-based materials hydration was developed by a proposed method. The porosity reduction is fast at the setting period. The results find that the pore discontinuity occurs faster at lower water/cement ratios than at higher water/cement ratios which is similar to the results of the Percolation method.

  11. Life Origination Hydrate Theory (LOH-Theory) and Mitosis and Replication Hydrate Theory (MRH-Theory): three-dimensional PC validation

    Science.gov (United States)

    Kadyshevich, E. A.; Dzyabchenko, A. V.; Ostrovskii, V. E.

    2014-04-01

    Size compatibility of the CH4-hydrate structure II and multi-component DNA fragments is confirmed by three-dimensional simulation; it is validation of the Life Origination Hydrate Theory (LOH-Theory).

  12. The role of water in gas hydrate dissociation

    Science.gov (United States)

    Circone, S.; Stern, L.A.; Kirby, S.H.

    2004-01-01

    When raised to temperatures above the ice melting point, gas hydrates release their gas in well-defined, reproducible events that occur within self-maintained temperature ranges slightly below the ice point. This behavior is observed for structure I (carbon dioxide, methane) and structure II gas hydrates (methane-ethane, and propane), including those formed with either H2O- or D2O-host frameworks, and dissociated at either ambient or elevated pressure conditions. We hypothesize that at temperatures above the H2O (or D2O) melting point: (1) hydrate dissociation produces water + gas instead of ice + gas, (2) the endothermic dissociation reaction lowers the temperature of the sample, causing the water product to freeze, (3) this phase transition buffers the sample temperatures within a narrow temperature range just below the ice point until dissociation goes to completion, and (4) the temperature depression below the pure ice melting point correlates with the average rate of dissociation and arises from solution of the hydrate-forming gas, released by dissociation, in the water phase at elevated concentrations. In addition, for hydrate that is partially dissociated to ice + gas at lower temperatures and then heated to temperatures above the ice point, all remaining hydrate dissociates to gas + liquid water as existing barriers to dissociation disappear. The enhanced dissociation rates at warmer temperatures are probably associated with faster gas transport pathways arising from the formation of water product.

  13. Anomalous preservation of pure methane hydrate at 1 atm

    Science.gov (United States)

    Stern, L.A.; Circone, S.; Kirby, S.H.; Durham, W.B.

    2001-01-01

    Direct measurement of decomposition rates of pure, polycrystalline methane hydrate reveals a thermal regime where methane hydrate metastably `preserves' in bulk by as much as 75 K above its nominal equilibrium temperature (193 K at 1 atm). Rapid release of the sample pore pressure at isothermal conditions between 242 and 271 K preserves up to 93% of the hydrate for at least 24 h, reflecting the greatly suppressed rates of dissociation that characterize this regime. Subsequent warming through the H2O ice point then induces rapid and complete dissociation, allowing controlled recovery of the total expected gas yield. This behavior is in marked contrast to that exhibited by methane hydrate at both colder (193-240 K) and warmer (272-290 K) test conditions, where dissociation rates increase monotonically with increasing temperature. Anomalous preservation has potential application for successful retrieval of natural gas hydrate or hydrate-bearing sediments from remote settings, as well as for temporary low-pressure transport and storage of natural gas.

  14. Gas hydrates: entrance to a methane age or climate threat?

    Energy Technology Data Exchange (ETDEWEB)

    Krey, Volker; Nakicenovic, Nebojsa; Grubler, Arnulf; O' Neill, Brian; Riahi, Keywan [International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, 2361 Laxenburg (Austria); Canadell, Josep G [Global Carbon Project, CSIRO Marine and Atmospheric Research, GPO Box 3023, Canberra, ACT 2601 (Australia); Abe, Yuichi [Social Science Consulting Unit, Japan Nus Co. Ltd, Loop-X Building 7F, 9-15 Kaigan 3-Chome, Minato-ku, Tokyo 108-0022 (Japan); Andruleit, Harald [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Stilleweg 2, 30655 Hannover (Germany); Archer, David [Department of the Geophysical Sciences at the University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States); Hamilton, Neil T M [WWF International Arctic Programme, Kristian Augusts gate 7a, 0130 Oslo (Norway); Johnson, Arthur [Hydrate Energy International, 612 Petit Berdot Drive, Kenner, LA 70065 (United States); Kostov, Veselin [Department of Physics and Astronomy, Johns Hopkins University, 3400 N Charles Street Baltimore, MD 21218 (United States); Lamarque, Jean-Francois [Atmospheric Chemistry Division, National Center for Atmospheric Research (NCAR), PO Box 3000, Boulder, CO 80307 (United States); Langhorne, Nicholas [US Office of Naval Research Global, Edison House, 223 Old Marylebone Road, London (United Kingdom); Nisbet, Euan G [Department of Geology, Royal Holloway, University of London, Egham, Surrey TW20 0EX (United Kingdom); Riedel, Michael [Earth and Planetary Sciences, McGill University, 3450 University Street, Montreal, QC, H3A 2A7 (Canada); Wang Weihua [Computer Network Information Center, Chinese Academy of Sciences, No. 4, 4th South Street, ZhongGuanCun, PO Box 349, Haidian District, Beijing 100080 (China); Yakushev, Vladimir, E-mail: krey@iiasa.ac.a [Gazprom VNIIGAZ LLC, Razvilka, Leninsky District, Moscow Region, 142717 (Russian Federation)

    2009-09-15

    Methane hydrates, ice-like compounds in which methane is held in crystalline cages formed by water molecules, are widespread in areas of permafrost such as the Arctic and in sediments on the continental margins. They are a potentially vast fossil fuel energy source but, at the same time, could be destabilized by changing pressure-temperature conditions due to climate change, potentially leading to strong positive carbon-climate feedbacks. To enhance our understanding of both the vulnerability of and the opportunity provided by methane hydrates, it is necessary (i) to conduct basic research that improves the highly uncertain estimates of hydrate occurrences and their response to changing environmental conditions, and (ii) to integrate the agendas of energy security and climate change which can provide an opportunity for methane hydrates-in particular if combined with carbon capture and storage-to be used as a 'bridge fuel' between carbon-intensive fossil energies and zero-emission energies. Taken one step further, exploitation of dissociating methane hydrates could even mitigate against escape of methane to the atmosphere. Despite these opportunities, so far, methane hydrates have been largely absent from energy and climate discussions, including global hydrocarbon assessments and the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.

  15. Postglacial response of Arctic Ocean gas hydrates to climatic amelioration

    Science.gov (United States)

    Serov, Pavel; Vadakkepuliyambatta, Sunil; Mienert, Jürgen; Patton, Henry; Portnov, Alexey; Silyakova, Anna; Panieri, Giuliana; Carroll, Michael L.; Carroll, JoLynn; Andreassen, Karin; Hubbard, Alun

    2017-06-01

    Seafloor methane release due to the thermal dissociation of gas hydrates is pervasive across the continental margins of the Arctic Ocean. Furthermore, there is increasing awareness that shallow hydrate-related methane seeps have appeared due to enhanced warming of Arctic Ocean bottom water during the last century. Although it has been argued that a gas hydrate gun could trigger abrupt climate change, the processes and rates of subsurface/atmospheric natural gas exchange remain uncertain. Here we investigate the dynamics between gas hydrate stability and environmental changes from the height of the last glaciation through to the present day. Using geophysical observations from offshore Svalbard to constrain a coupled ice sheet/gas hydrate model, we identify distinct phases of subglacial methane sequestration and subsequent release on ice sheet retreat that led to the formation of a suite of seafloor domes. Reconstructing the evolution of this dome field, we find that incursions of warm Atlantic bottom water forced rapid gas hydrate dissociation and enhanced methane emissions during the penultimate Heinrich event, the Bølling and Allerød interstadials, and the Holocene optimum. Our results highlight the complex interplay between the cryosphere, geosphere, and atmosphere over the last 30,000 y that led to extensive changes in subseafloor carbon storage that forced distinct episodes of methane release due to natural climate variability well before recent anthropogenic warming.

  16. Three-phase flow of submarine gas hydrate pipe transport

    Institute of Scientific and Technical Information of China (English)

    李立; 徐海良; 杨放琼

    2015-01-01

    In the hydraulic transporting process of cutter-suction mining natural gas hydrate, when the temperature−pressure equilibrium of gas hydrate is broken, gas hydrates dissociate into gas. As a result, solid−liquid two-phase flow (hydrate and water) transforms into gas−solid−liquid three-phase flow (methane, hydrate and water) inside the pipeline. The Euler model and CFD-PBM model were used to simulate gas−solid−liquid three-phase flow. Numerical simulation results show that the gas and solid phase gradually accumulate to the center of the pipe. Flow velocity decreases from center to boundary of the pipe along the radial direction. Comparison of numerical simulation results of two models reveals that the flow state simulated by CFD-PBM model is more uniform than that simulated by Euler model, and the main behavior of the bubble is small bubbles coalescence to large one. Comparison of numerical simulation and experimental investigation shows that the values of flow velocity and gas fraction in CFD-PBM model agree with experimental data better than those in Euler model. The proposed PBM model provides a more accurate and effective way to estimate three-phase flow state of transporting gas hydrate within the submarine pipeline.

  17. SCHEMES OF GAS PRODUCTION FROM NATURAL GAS HYDRATES

    Institute of Scientific and Technical Information of China (English)

    李淑霞; 陈月明; 杜庆军

    2003-01-01

    Natural gas hydrates are a kind of nonpolluting and high quality energy resources for future, the reserves of which are about twice of the carbon of the current fossil energy (petroleum, natural gas and coal) on the earth. And it will be the most important energy for the 21st century. The energy balance and numerical simulation are applied to study the schemes of the natural gas hydrates production in this paper,and it is considered that both depressurization and thermal stimulation are effective methods for exploiting natural gas hydrates, and that the gas production of the thermal stimulation is higher than that of the depressurization. But thermal stimulation is non-economic because it requires large amounts of energy.Therefore the combination of the two methods is a preferable method for the current development of the natural gas hydrates. The main factors which influence the production of natural gas hydrates are: the temperature of injected water, the injection rate, the initial saturation of the hydrates and the initial temperature of the reservoir which is the most important factor.

  18. Nonequilibrium adiabatic molecular dynamics simulations of methane clathrate hydrate decomposition

    Science.gov (United States)

    Alavi, Saman; Ripmeester, J. A.

    2010-04-01

    Nonequilibrium, constant energy, constant volume (NVE) molecular dynamics simulations are used to study the decomposition of methane clathrate hydrate in contact with water. Under adiabatic conditions, the rate of methane clathrate decomposition is affected by heat and mass transfer arising from the breakup of the clathrate hydrate framework and release of the methane gas at the solid-liquid interface and diffusion of methane through water. We observe that temperature gradients are established between the clathrate and solution phases as a result of the endothermic clathrate decomposition process and this factor must be considered when modeling the decomposition process. Additionally we observe that clathrate decomposition does not occur gradually with breakup of individual cages, but rather in a concerted fashion with rows of structure I cages parallel to the interface decomposing simultaneously. Due to the concerted breakup of layers of the hydrate, large amounts of methane gas are released near the surface which can form bubbles that will greatly affect the rate of mass transfer near the surface of the clathrate phase. The effects of these phenomena on the rate of methane hydrate decomposition are determined and implications on hydrate dissociation in natural methane hydrate reservoirs are discussed.

  19. Wound healing and hyper-hydration: a counterintuitive model.

    Science.gov (United States)

    Rippon, M G; Ousey, K; Cutting, K F

    2016-02-01

    Winter's seminal work in the 1960s relating to providing an optimal level of moisture to aid wound healing (granulation and re-epithelialisation) has been the single most effective advance in wound care over many decades. As such the development of advanced wound dressings that manage the fluidic wound environment have provided significant benefits in terms of healing to both patient and clinician. Although moist wound healing provides the guiding management principle, confusion may arise between what is deemed to be an adequate level of tissue hydration and the risk of developing maceration. In addition, the counter-intuitive model 'hyper-hydration' of tissue appears to frustrate the moist wound healing approach and advocate a course of intervention whereby tissue is hydrated beyond what is a normally acceptable therapeutic level. This paper discusses tissue hydration, the cause and effect of maceration and distinguishes these from hyper-hydration of tissue. The rationale is to provide the clinician with a knowledge base that allows optimisation of treatment and outcomes and explains the reasoning behind wound healing using hyper-hydration. Declaration of interest: K. Cutting is a Clinical Research Consultant to the medical device and biotechnology industry. M. Rippon is Visiting Clinical Research Fellow, University of Huddersfield and K. Ousey provides consultancy for a range of companies through the University of Huddersfield including consultancy services for Paul Hartmann Ltd on HydroTherapy products.

  20. Pectin as an Extraordinary Natural Kinetic Hydrate Inhibitor

    Science.gov (United States)

    Xu, Shurui; Fan, Shuanshi; Fang, Songtian; Lang, Xuemei; Wang, Yanhong; Chen, Jun

    2016-03-01

    Pectin as a novel natural kinetic hydrate inhibitor, expected to be eco-friendly and sufficiently biodegradable, was studied in this paper. The novel crystal growth inhibition (CGI) and standard induction time methods were used to evaluate its effect as hydrate inhibitor. It could successfully inhibit methane hydrate formation at subcooling temperature up to 12.5 °C and dramatically slowed the hydrate crystal growth. The dosage of pectin decreased by 66% and effective time extended 10 times than typical kinetic inhibitor. Besides, its maximum growth rate was no more than 2.0%/h, which was far less than 5.5%/h of growth rate for PVCap at the same dosage. The most prominent feature was that it totally inhibited methane hydrate crystal rapid growth when hydrate crystalline occurred. Moreover, in terms of typical natural inhibitors, the inhibition activity of pectin increased 10.0-fold in induction time and 2.5-fold in subcooling temperature. The extraordinary inhibition activity is closely related to its hydrogen bonding interaction with water molecules and the hydrophilic structure. Finally, the biodegradability and economical efficiency of pectin were also taken into consideration. The results showed the biodegradability improved 75.0% and the cost reduced by more than 73.3% compared to typical commercial kinetic inhibitors.

  1. Hydration Dependence of Energy Relaxation Time for Cytochrome C

    Science.gov (United States)

    Ye, Shuji; Chen, Jing-Yin; Knab, Joseph R.; Markelz, Andrea

    2006-03-01

    Hydration plays a critical role in protein dynamics. Here we consider the effects of hydration on energy relaxation for an electronically excited heme protein cytochrome c. We measure the hydration dependence of energy relaxation time of cytochrome C films after photoexcitation in the Soret regionusing two-color pump/probe time resolved transmission measurements. Thin films were prepared from cytochrome C/ Trizma buffer solutions and mounted in a hydration controlled cell. We used 400nm (˜3 mW) to pump the B band and 800 nm (˜1 mW) to probe the III band. The III band corresponds to the charge-transfer transition between heme π and iron d orbital, and is assigned to the ground electronic state of the heme. Therefore this band can be used to probe the ground state population. Three separate dynamic components were observed: a very fast transient τ1 ˜ 200 fs; a several hundred femtosecond component (τ2); and a recovery of the ground state absorption(τ3). We find τ3 apparently decreases with decreasing hydration while τ1 and τ2 are independent of hydration.

  2. Scale down of the inactivated polio vaccine production process

    NARCIS (Netherlands)

    Thomassen, Y.E.; Oever, van 't R.; Vinke, C.M.; Spiekstra, A.; Wijffels, R.H.; Pol, van der L.A.; Bakker, W.A.M.

    2013-01-01

    The anticipated increase in the demand for inactivated polio vaccines resulting from the success in the polio eradication program requires an increase in production capacity and cost price reduction of the current inactivated polio vaccine production processes. Improvement of existing production pro

  3. Mechanisms of Escherichia coli inactivation by several disinfectants.

    Science.gov (United States)

    Cho, Min; Kim, Jaeeun; Kim, Jee Yeon; Yoon, Jeyong; Kim, Jae-Hong

    2010-06-01

    The objective of this study was to elucidate dominant mechanisms of inactivation, i.e. surface attack versus intracellular attack, during application of common water disinfectants such as ozone, chlorine dioxide, free chlorine and UV irradiation. Escherichia coli was used as a representative microorganism. During cell inactivation, protein release, lipid peroxidation, cell permeability change, damage in intracellular enzyme and morphological change were comparatively examined. For the same level of cell inactivation by chemical disinfectants, cell surface damage was more pronounced with strong oxidant such as ozone while damage in inner cell components was more apparent with weaker oxidant such as free chlorine. Chlorine dioxide showed the inactivation mechanism between these two disinfectants. The results suggest that the mechanism of cell inactivation is primarily related to the reactivity of chemical disinfectant. In contrast to chemical disinfectants, cell inactivation by UV occurred without any changes measurable with the methods employed. Understanding the differences in inactivation mechanisms presented herein is critical to identify rate-limiting steps involved in the inactivation process as well as to develop more effective disinfection strategies.

  4. Scale down of the inactivated polio vaccine production process

    NARCIS (Netherlands)

    Thomassen, Y.E.; Oever, van 't R.; Vinke, C.M.; Spiekstra, A.; Wijffels, R.H.; Pol, van der L.A.; Bakker, W.A.M.

    2013-01-01

    The anticipated increase in the demand for inactivated polio vaccines resulting from the success in the polio eradication program requires an increase in production capacity and cost price reduction of the current inactivated polio vaccine production processes. Improvement of existing production pro

  5. Scale down of the inactivated polio vaccine production process

    NARCIS (Netherlands)

    Thomassen, Y.E.; Oever, van 't R.; Vinke, C.M.; Spiekstra, A.; Wijffels, R.H.; Pol, van der L.A.; Bakker, W.A.M.

    2013-01-01

    The anticipated increase in the demand for inactivated polio vaccines resulting from the success in the polio eradication program requires an increase in production capacity and cost price reduction of the current inactivated polio vaccine production processes. Improvement of existing production

  6. Contribution of hydration to protein folding thermodynamics. I. The enthalpy of hydration.

    Science.gov (United States)

    Makhatadze, G I; Privalov, P L

    1993-07-20

    The enthalpy of hydration of polar and non-polar groups upon protein unfolding has been estimated for four globular proteins in the temperature range 5 to 125 degrees C, using structural information on the groups in these proteins exposed to water in the native and unfolded states and volume-corrected calorimetric information on the enthalpy and heat capacity of transfer into water of various model compounds. It has been shown that the enthalpy of hydration of polar groups greatly exceeds the enthalpy of hydration of non-polar groups. At low temperatures both these enthalpies are negative and change in opposite direction with increasing temperature. Subtracting the total enthalpy of hydration of polar and non-polar groups from the calorimetrically determined enthalpy of protein unfolding, the total enthalpy of internal interactions maintaining the native protein structure has been determined. Using thermodynamic information on the sublimation of organic crystals, the total enthalpy was divided into two components: one associated with the interactions between the non-polar groups (van der Waals interaction) and the rest associated with the interactions between polar groups (hydrogen bonding). This made it possible to estimate the overall enthalpies of disruption of contacts between the polar groups with their exposure to water and between the non-polar groups with their exposure to water. It appears that these enthalpies have opposite signs in the temperature range considered and change in opposite directions with increasing temperature. The enthalpy of transfer of non-polar groups from the protein interior into water is negative below 25 degrees C and positive above. The enthalpy of transfer of polar groups from the protein interior into water is positive at low temperatures and becomes negative at higher temperatures. Over the considered temperature range, however, the enthalpy of transfer of non-polar groups dominates. This results in a positive enthalpy of

  7. On the free energy of ionic hydration

    CERN Document Server

    Hummer, G; García, A E; Hummer, Gerhard; Pratt, Lawrence R.; Garcia, Angel E.

    1995-01-01

    The hydration free energies of ions exhibit an approximately quadratic dependence on the ionic charge, as predicted by the Born model. We analyze this behavior using second-order perturbation theory. This provides effective methods to calculating free energies from equilibrium computer simulations. The average and the fluctuation of the electrostatic potential at charge sites appear as the first coefficients in a Taylor expansion of the free energy of charging. Combining the data from different charge states allows calculation of free-energy profiles as a function of the ionic charge. The first two Taylor coefficients of the free-energy profiles can be computed accurately from equi- librium simulations; but they are affected by a strong system-size dependence. We apply corrections for these finite-size effects by using Ewald lattice sum- mation and adding the self-interactions consistently. Results are presented for a model ion with methane-like Lennard-Jones parameters in SPC water. We find two very closely ...

  8. Coupled analysis of a backfill hydration test

    Science.gov (United States)

    Alonso, E. E.; Lloret, A.; Delahaye, C. H.; Vaunat, J.; Gens, A.; Volckaert, G.

    1998-01-01

    BACCHUS2 in situ isothermal wetting experiment has been analysed by means of a coupled flow-deformation approach. Backfill material, a mixture of Boom clay powder and high density pellets, has been extensively tested in the laboratory in order to determine its hydraulic and mechanical properties. Parameters of constitutive equations were derived from this experimental data base. Two mechanical constitutive models have been used in the simulation of the in situ experiment: a state surface approach and an elastoplastic model. Calculations have shown several features of the hydration process which help to understand the behaviour of expansive clay barriers. Predictions using both models have been compared with each other and with actual measurement records. This has allowed a discussion of the comparative mertis of both approaches and the identification of some critical parameters of backfill behaviour. Overall agreement between calculations and field measurements is encouraging and shows the potential of the methods developed to model the behaviour of engineered clay barriers in the context of nuclear waste disposal.

  9. Mechanism and kinetics of hydrated electron diffusion

    CERN Document Server

    Tay, Kafui A; Boutin, Anne; 10.1063/1.2964101

    2012-01-01

    Molecular dynamics simulations are used to study the mechanism and kinetics of hydrated electron diffusion. The electron center of mass is found to exhibit Brownian-type behavior with a diffusion coefficient considerably greater than that of the solvent. As previously postulated by both experimental and theoretical works, the instantaneous response of the electron to the librational motions of surrounding water molecules constitutes the principal mode of motion. The diffusive mechanism can be understood within the traditional framework of transfer diffusion processes, where the diffusive step is akin to the exchange of an extramolecular electron between neighboring water molecules. This is a second-order process with a computed rate constant of 5.0 ps^{-1} at 298 K. In agreement with experiment the electron diffusion exhibits Arrhenius behavior over the temperature range of 298-400 K. We compute an activation energy of 8.9 kJ/mol. Through analysis of Arrhenius plots and the application of a simple random walk...

  10. DNA hydration studied by neutron fiber diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, W.; Forsyth, V.T.; Mahendrasingam, A.; Langan, P.; Pigram, W.J. [Keele Univ. (United Kingdom)] [and others

    1994-12-31

    The development of neutron high angle fiber diffraction to investigate the location of water around the deoxyribonucleic acid (DNA) double-helix is described. The power of the technique is illustrated by its application to the D and A conformations of DNA using the single crystal diffractometer, D19, at the Institute Laue-Langevin, Grenoble and the time of flight diffractometer, SXD, at the Rutherford Appleton ISIS Spallation Neutron Source. These studies show the existence of bound water closely associated with the DNA. The patterns of hydration in these two DNA conformations are quite distinct and are compared to those observed in X-ray single crystal studies of two-stranded oligodeoxynucleotides. Information on the location of water around the DNA double-helix from the neutron fiber diffraction studies is combined with that on the location of alkali metal cations from complementary X-ray high angle fiber diffraction studies at the Daresbury Laboratory SRS using synchrotron radiation. These analyses emphasize the importance of viewing DNA, water and ions as a single system with specific interactions between the three components and provide a basis for understanding the effect of changes in the concentration of water and ions in inducing conformations] transitions in the DNA double-helix.

  11. Dissolution Rates of Synthetic Methane Hydrate and Carbon Dioxide Hydrate in Undersaturated Seawater at 1000m depth

    Science.gov (United States)

    Rehder, G.; Kirby, S. H.; Durham, W. B.; Brewer, P. G.; Stern, L.; Peltzer, E. T.; Pinkston, J.

    2001-12-01

    Dissolution of synthetic methane and carbon dioxide hydrates was monitored after their transport to the ocean floor at 1000m depth. Cylindrical test specimens were initially grown in the laboratory by combining either cold, pressurized methane gas or pressurized liquid CO2 with sieved granular water ice, then heating the reactants through the H2O melting point. Samples were then hydrostatically compacted to near-zero porosity, with resulting geometry of approximately 2.5 cm in diameter by 3-4 cm in length. Two samples each of methane and carbon dioxide hydrate were placed in a custom-made sample display rack having individual compartments for each sample with a transparent polycarbonate front window, and side and back walls of a flexible fine-mesh screen that permitted seawater flow around the hydrates. The sample rack was then transferred to the ocean in a stainless steel transport vessel pressurized with 10 MPa methane using the (ROV) Ventana. On the seafloor, the sample display rack was removed from the pressure vessel and secured in a stand attached to an autonomous underwater video recorder system using a time-programmable Hi8 video recorder. The samples were continuously monitored for 2.30 h using VentanaIs HDTV camera system, then followed by 20.75 h observation with the autonomous Hi8 time-lapse camera system (15 s every 0.25 h), and additional 3.33 h HDTV observation at the end of the experiment. Loss of volume and dissolution rates of the hydrates were derived from the measurement of the change of the projected diameter of the individual samples over time. During the first 2.30 h, the diameter of the two CO2 hydrates decreased from 22 mm to 15 and 13 mm, respectively. Diameter loss followed a generally linear trend of 0.94 and 1.20 μ m/sec, corresponding to a dissolution rate of 13 to 17 mole CO2/m2h. Similar short-term oscillations about this linear trend were observed on both samples, suggesting a link to bottom current velocity. The CH4 hydrates

  12. Dynamic morphology of gas hydrate on a methane bubble in water: Observations and new insights for hydrate film models

    National Research Council Canada - National Science Library

    Warzinski, Robert P; Lynn, Ronald; Haljasmaa, Igor; Leifer, Ira; Shaffer, Frank; Anderson, Brian J; Levine, Jonathan S

    2014-01-01

    Predicting the fate of subsea hydrocarbon gases escaping into seawater is complicated by potential formation of hydrate on rising bubbles that can enhance their survival in the water column, allowing...

  13. Chlorophyll mediated photodynamic inactivation of blue laser on Streptococcus mutans

    Science.gov (United States)

    Astuti, Suryani Dyah; Zaidan, A.; Setiawati, Ernie Maduratna; Suhariningsih

    2016-03-01

    Photodynamic inactivation is an inactivation method in microbial pathogens that utilize light and photosensitizer. This study was conducted to investigate photodynamic inactivation effects of low intensity laser exposure with various dose energy on Streptococcus mutans bacteria. The photodynamic inactivation was achieved with the addition of chlorophyll as photosensitizers. To determine the survival percentage of Streptococcus mutans bacteria after laser exposure, the total plate count method was used. For this study, the wavelength of the laser is 405 nm and variables of energy doses are 1.44, 2.87, 4.31, 5.74, 7.18, and 8.61 in J/cm2. The results show that exposure to laser with energy dose of 7.18 J/cm2 has the best photodynamic inactivation with a decrease of 78% in Streptococcus

  14. Pathogen Inactivation of red cells: challenges and opportunities

    Institute of Scientific and Technical Information of China (English)

    Stephen J. Wagner

    2006-01-01

    @@ Introduction Virus inactivation methods for blood have been explored as a means to further reduce the risk from tested agents and to decrease the risk of emerging or variant agents for whom no deferral or effective screening methods are available. Although inactivation methods promise to reduce transfusion-related infectious disease risk, these methods are not perfect. Most techniques for pathogen reduction will not kill bacterial spores, or inactivate bacterial endotoxin, prion protein, or certain non-enveloped viruses whose tightly packed capsid proteins prevent access of the virucidal agent to its nucleic acid target. In addition,various inactivation methods have been known to decrease blood cell yield, affect blood cell recovery or survival, and may pose risk to recipients or blood center workers. My presentation today will review two methods for pathogen inactivation of red cells.

  15. Factors affecting cellulose hydrolysis based on inactivation of adsorbed enzymes.

    Science.gov (United States)

    Ye, Zhuoliang; Berson, R Eric

    2014-09-01

    The rate of enzymatic hydrolysis of cellulose reaction is known to decrease significantly as the reaction proceeds. Factors such as reaction temperature, time, and surface area of substrate that affect cellulose conversion were analyzed relative to their role in a mechanistic model based on first order inactivation of adsorbed cellulases. The activation energies for the hydrolytic step and inactivation step were very close in magnitude: 16.3 kcal mol(-1) for hydrolysis and 18.0 kcal mol(-1) for inactivation, respectively. Therefore, increasing reaction temperature would cause a significant increase in the inactivation rate in addition to the catalytic reaction rate. Vmax,app was only 20% or less of the value at 72 h compared to at 2h as a result of inactivation of adsorbed cellulases, suggesting prolonged hydrolysis is not an efficient way to improve cellulose hydrolysis. Hydrolysis rate increased with corresponding increases in available substrate surface binding area. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. [Inactivation of T4 phage in water environment using proteinase].

    Science.gov (United States)

    Lü, Wen-zhou; Yang, Qing-xiang; Zhang, Yu; Yang, Min; Zhu, Chun-fang

    2004-09-01

    The inactivation effectiveness of proteinase to viruses was investigated by using T4 phage as a model virus. The results showed that the inactivation effectiveness of proteinase to T4 phage was obvious. In the optimum conditions and 67.5 u/mL concentration, the inactivation rate of proteinase K to T4 phage in sterilized water and in sewage achieved 99.4% and 49.4% respectively in an hour, and achieved >99.9% and 81.1% in three hours. The inactivation rate of the industrial proteinase 1398 to T4 phage in sterilized water achieved 74.4% in an hour. The effects of pH and temperature on the inactivation effectiveness was not evident.

  17. Inactivation of Chikungunya virus by 1,5 iodonapthyl azide

    Directory of Open Access Journals (Sweden)

    Sharma Anuj

    2012-12-01

    Full Text Available Abstract Background Chikungunya virus (CHIKV is an arthropod borne alphavirus of the family Togaviridae. CHIKV is a reemerging virus for which there is no safe prophylactic vaccine. A live attenuated strain of CHIKV, CHIK181/25, was previously demonstrated to be highly immunogenic in humans, however, it showed residual virulence causing transient arthralgia. Findings In this study, we demonstrate the complete inactivation of CHIKV181/25 by 1,5 iodonapthyl azide (INA. No cytopathic effect and virus replication was observed in cells infected with the INA-inactivated CHIKV. However, a reduction in the INA-inactivated CHIK virus-antibody binding capacity was observed by western blot analysis. Conclusion INA completely inactivated CHIKV and can further be explored for developing an inactivated-CHIKV vaccine.

  18. Strong purifying selection at genes escaping X chromosome inactivation.

    Science.gov (United States)

    Park, Chungoo; Carrel, Laura; Makova, Kateryna D

    2010-11-01

    To achieve dosage balance of X-linked genes between mammalian males and females, one female X chromosome becomes inactivated. However, approximately 15% of genes on this inactivated chromosome escape X chromosome inactivation (XCI). Here, using a chromosome-wide analysis of primate X-linked orthologs, we test a hypothesis that such genes evolve under a unique selective pressure. We find that escape genes are subject to stronger purifying selection than inactivated genes and that positive selection does not significantly affect the evolution of these genes. The strength of selection does not differ between escape genes with similar versus different expression levels in males versus females. Intriguingly, escape genes possessing Y homologs evolve under the strongest purifying selection. We also found evidence of stronger conservation in gene expression levels in escape than inactivated genes. We hypothesize that divergence in function and expression between X and Y gametologs is driving such strong purifying selection for escape genes.

  19. UV inactivation of pathogenic and indicator microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Chang, J.C.; Ossoff, S.F.; Lobe, D.C.; Dorfman, M.H.; Dumais, C.M.; Qualls, R.G.; Johnson, J.D.

    1985-06-01

    Survival was measured as a function of the dose of germicidal UV light for the bacteria Escherichia coli, Salmonella typhi, Shigella sonnei, Streptococcus faecalis, Staphylococcus aureus, and Bacillus subtilis spores, the enteric viruses poliovirus type 1 and simian rotavirus SA11, the cysts of the protozoan Acanthamoeba castellanii, as well as for total coliforms and standard plate count microorganisms from secondary effluent. The doses of UV light necessary for a 99.9% inactivation of the cultured vegetative bacteria, total coliforms, and standard plate count microorganisms were comparable. However, the viruses, the bacterial spores, and the amoebic cysts required about 3 to 4 times, 9 times, and 15 times, respectively, the dose required for E. coli. These ratios covered a narrower relative dose range than that previously reported for chlorine disinfection of E. coli, viruses, spores, and cysts.

  20. Inactivation of microbes using ultrasound: a review.

    Science.gov (United States)

    Piyasena, P; Mohareb, E; McKellar, R C

    2003-11-01

    Alternative methods for pasteurization and sterilization are gaining importance, due to increased consumer demand for new methods of food processing that have a reduced impact on nutritional content and overall food quality. Ultrasound processing or sonication is one of the alternative technologies that has shown promise in the food industry. Sonication alone is not very effective in killing bacteria in food; however, the use of ultrasound coupled with pressure and/or heat is promising. Thermosonic (heat plus sonication), manosonic (pressure plus sonication), and manothermosonic (heat and pressure plus sonication) treatments are likely the best methods to inactivate microbes, as they are more energy-efficient and effective in killing microorganisms. Ultrasonic processing is still in its infancy and requires a great deal of future research in order to develop the technology on an industrial scale, and to more fully elucidate the effect of ultrasound on the properties of foods.

  1. Esterase resistant to inactivation by heavy metals

    KAUST Repository

    El, Dorry Hamza

    2014-09-25

    EstATII is an esterase that a halotolerant, thermophilic and resistant to a spectrum of heavy metals including toxic concentration of metals. It was isolated from the lowest convective layer of the Atlantis II Red Sea brine pool. The Atlantis II brine pool is an extreme environment that possesses multiple harsh conditions such as; high temperature, salinity, pH and high concentration of metals, including toxic heavy metals. A fosmid metagenomic library using DNA isolated from the lowest convective layer this pool was used to identify EstATII. Polynucleotides encoding EstATII and similar esterases are disclosed and can be used to make EstATII. EstATII or compositions or apparatuses that contain it may be used in various processes employing lipases/esterases especially when these processes are performed under harsh conditions that inactivate other kinds of lipases or esterases.

  2. Formation and Dissociation of Methane Hydrates from Seawater in Consolidated Sand: Mimicking Methane Hydrate Dynamics beneath the Seafloor

    Directory of Open Access Journals (Sweden)

    Prasad B. Kerkar

    2013-11-01

    Full Text Available Methane hydrate formation and dissociation kinetics were investigated in seawater-saturated consolidated Ottawa sand-pack under sub-seafloor conditions to study the influence of effective pressure on formation and dissociation kinetics. To simulate a sub-seafloor environment, the pore-pressure was varied relative to confining pressure in successive experiments. Hydrate formation was achieved by methane charging followed by sediment cooling. The formation of hydrates was delayed with increasing degree of consolidation. Hydrate dissociation by step-wise depressurization was instantaneous, emanating preferentially from the interior of the sand-pack. Pressure drops during dissociation and in situ temperature controlled the degree of endothermic cooling within sediments. In a closed system, the post-depressurization dissociation was succeeded by thermally induced dissociation and pressure-temperature conditions followed theoretical methane-seawater equilibrium conditions and exhibited excess pore pressure governed by the pore diameter. These post-depressurization equilibrium values for the methane hydrates in seawater saturated consolidated sand-pack were used to estimate the enthalpy of dissociation of 55.83 ± 1.41 kJ/mol. These values were found to be lower than those reported in earlier literature for bulk hydrates from seawater (58.84 kJ/mol and pure water (62.61 kJ/mol due to excess pore pressure generated within confined sediment system under investigation. However, these observations could be significant in the case of hydrate dissociation in a subseafloor environment where dissociation due to depressurization could result in an instantaneous methane release followed by slow thermally induced dissociation. The excess pore pressure generated during hydrate dissociation could be higher within fine-grained sediments with faults and barriers present in subseafloor settings which could cause shifting in geological layers.

  3. Ion channels to inactivate neurons in Drosophila

    Directory of Open Access Journals (Sweden)

    James J L Hodge

    2009-08-01

    Full Text Available Ion channels are the determinants of excitability; therefore, manipulation of their levels and properties provides an opportunity for the investigator to modulate neuronal and circuit function. There are a number of ways to suppress electrical activity in Drosophila neurons, for instance, over-expression of potassium channels (i.e. Shaker Kv1, Shaw Kv3, Kir2.1 and DORK that are open at resting membrane potential. This will result in increased potassium efflux and membrane hyperpolarisation setting resting membrane potential below the threshold required to fire action potentials. Alternatively over-expression of other channels, pumps or co-transporters that result in a hyperpolarised membrane potential will also prevent firing. Lastly, neurons can be inactivated by, disrupting or reducing the level of functional voltage-gated sodium (Nav1 paralytic or calcium (Cav2 cacophony channels that mediate the depolarisation phase of action potentials. Similarly, strategies involving the opposite channel manipulation should allow net depolarisation and hyperexcitation in a given neuron. These changes in ion channel expression can be brought about by the versatile transgenic (i.e. Gal4/UAS based systems available in Drosophila allowing fine temporal and spatial control of (channel transgene expression. These systems are making it possible to electrically inactivate (or hyperexcite any neuron or neural circuit in the fly brain, and much like an exquisite lesion experiment, potentially elucidate whatever interesting behaviour or phenotype each network mediates. These techniques are now being used in Drosophila to reprogram electrical activity of well-defined circuits and bring about robust and easily quantifiable changes in behaviour, allowing different models and hypotheses to be rapidly tested.

  4. Human male meiotic sex chromosome inactivation.

    Science.gov (United States)

    de Vries, Marieke; Vosters, Sanne; Merkx, Gerard; D'Hauwers, Kathleen; Wansink, Derick G; Ramos, Liliana; de Boer, Peter

    2012-01-01

    In mammalian male gametogenesis the sex chromosomes are distinctive in both gene activity and epigenetic strategy. At first meiotic prophase the heteromorphic X and Y chromosomes are placed in a separate chromatin domain called the XY body. In this process, X,Y chromatin becomes highly phosphorylated at S139 of H2AX leading to the repression of gonosomal genes, a process known as meiotic sex chromosome inactivation (MSCI), which has been studied best in mice. Post-meiotically this repression is largely maintained. Disturbance of MSCI in mice leads to harmful X,Y gene expression, eventuating in spermatocyte death and sperm heterogeneity. Sperm heterogeneity is a characteristic of the human male. For this reason we were interested in the efficiency of MSCI in human primary spermatocytes. We investigated MSCI in pachytene spermatocytes of seven probands: four infertile men and three fertile controls, using direct and indirect in situ methods. A considerable degree of variation in the degree of MSCI was detected, both between and within probands. Moreover, in post-meiotic stages this variation was observed as well, indicating survival of spermatocytes with incompletely inactivated sex chromosomes. Furthermore, we investigated the presence of H3K9me3 posttranslational modifications on the X and Y chromatin. Contrary to constitutive centromeric heterochromatin, this heterochromatin marker did not specifically accumulate on the XY body, with the exception of the heterochromatic part of the Y chromosome. This may reflect the lower degree of MSCI in man compared to mouse. These results point at relaxation of MSCI, which can be explained by genetic changes in sex chromosome composition during evolution and candidates as a mechanism behind human sperm heterogeneity.

  5. Human male meiotic sex chromosome inactivation.

    Directory of Open Access Journals (Sweden)

    Marieke de Vries

    Full Text Available In mammalian male gametogenesis the sex chromosomes are distinctive in both gene activity and epigenetic strategy. At first meiotic prophase the heteromorphic X and Y chromosomes are placed in a separate chromatin domain called the XY body. In this process, X,Y chromatin becomes highly phosphorylated at S139 of H2AX leading to the repression of gonosomal genes, a process known as meiotic sex chromosome inactivation (MSCI, which has been studied best in mice. Post-meiotically this repression is largely maintained. Disturbance of MSCI in mice leads to harmful X,Y gene expression, eventuating in spermatocyte death and sperm heterogeneity. Sperm heterogeneity is a characteristic of the human male. For this reason we were interested in the efficiency of MSCI in human primary spermatocytes. We investigated MSCI in pachytene spermatocytes of seven probands: four infertile men and three fertile controls, using direct and indirect in situ methods. A considerable degree of variation in the degree of MSCI was detected, both between and within probands. Moreover, in post-meiotic stages this variation was observed as well, indicating survival of spermatocytes with incompletely inactivated sex chromosomes. Furthermore, we investigated the presence of H3K9me3 posttranslational modifications on the X and Y chromatin. Contrary to constitutive centromeric heterochromatin, this heterochromatin marker did not specifically accumulate on the XY body, with the exception of the heterochromatic part of the Y chromosome. This may reflect the lower degree of MSCI in man compared to mouse. These results point at relaxation of MSCI, which can be explained by genetic changes in sex chromosome composition during evolution and candidates as a mechanism behind human sperm heterogeneity.

  6. Pressure-Inactivated Virus: A Promising Alternative for Vaccine Production.

    Science.gov (United States)

    Silva, Jerson L; Barroso, Shana P C; Mendes, Ygara S; Dumard, Carlos H; Santos, Patricia S; Gomes, Andre M O; Oliveira, Andréa C

    2015-01-01

    In recent years, many applications in diverse scientific fields with various purposes have examined pressure as a thermodynamic parameter. Pressure studies on viruses have direct biotechnological applications. Currently, most studies that involve viral inactivation by HHP are found in the area of food engineering and focus on the inactivation of foodborne viruses. Nevertheless, studies of viral inactivation for other purposes have also been conducted. HHP has been shown to be efficient in the inactivation of many viruses of clinical importance and the use of HHP approach has been proposed for the development of animal and human vaccines. Several studies have demonstrated that pressure can result in virus inactivation while preserving immunogenic properties. Viruses contain several components that can be susceptible to the effects of pressure. HHP has been a valuable tool for assessing viral structure function relationships because the viral structure is highly dependent on protein-protein interactions. In the case of small icosahedral viruses, incremental increases in pressure produce a progressive decrease in the folding structure when moving from assembled capsids to ribonucleoprotein intermediates (in RNA viruses), free dissociated units (dimers and/or monomers) and denatured monomers. High pressure inactivates enveloped viruses by trapping their particles in a fusion-like intermediate state. The fusogenic state, which is characterized by a smaller viral volume, is the final conformation promoted by HHP, in contrast with the metastable native state, which is characterized by a larger volume. The combined effects of high pressure with other factors, such as low or subzero temperature, pH and agents in sub-denaturing conditions (urea), have been a formidable tool in the assessment of the component's structure, as well as pathogen inactivation. HHP is a technology for the production of inactivated vaccines that are free of chemicals, safe and capable of inducing

  7. Study on molecular controlled mining system of methane hydrate; Methane hydrate no bunshi seigyo mining ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Kuriyagawa, M.; Saito, T.; Kobayashi, H.; Karasawa, H.; Kiyono , F.; Nagaoki, R.; Yamamoto, Y.; Komai, T.; Haneda, H.; Takahashi, Y. [National Institute for Resources and Environment, Tsukuba (Japan); Nada, H. [Science and Technology Agency, Tokyo (Japan)

    1997-02-01

    Basic studies are conducted for the collection of methane from the methane hydrate that exists at levels deeper than 500m in the sea. The relationship between the hydrate generation mechanism and water cluster structure is examined by use of mass spectronomy. It is found that, among the stable liquid phase clusters, the (H2O)21H{sup +} cluster is the most stable. Stable hydrate clusters are in presence in quantities, and participate in the formation of hydrate crystal nuclei. For the elucidation of the nucleus formation mechanism, a kinetic simulation is conducted of molecules in the cohesion system consisting of water and methane molecules. Water molecules that array near methane molecules at the normal pressure is disarrayed under a higher pressure for rearray into a hydrate structure. Hydrate formation and breakdown in the three-phase equilibrium state of H2O, CH4, and CO2 at a low temperature and high pressure are tested, which discloses that supercooling is required for formation, that it is possible to extract CH4 first for replacement by guest molecule CO2 since CO2 is stabler than CH4 at a lower pressure or higher temperature, and that formation is easier to take place when the grain diameter is larger at the formation point since larger grain diameters result in a higher formation temperature. 3 figs.

  8. Hydrate Evolution in Response to Ongoing Environmental Shifts

    Energy Technology Data Exchange (ETDEWEB)

    Rempel, Alan [Univ. of Oregon, Eugene, OR (United States)

    2015-12-31

    Natural gas hydrates have the potential to become a vital domestic clean-burning energy source. However, past changes in environmental conditions have caused hydrates to become unstable and trigger both massive submarine landslides and the development of crater-like pockmarks, thereby releasing methane into the overlying seawater and atmosphere, where it acts as a powerful greenhouse gas. This project was designed to fill critical gaps in our understanding of domestic hydrate resources and improve forecasts for their response to environmental shifts. Project work can be separated into three interrelated components, each involving the development of predictive mathematical models. The first project component concerns the role of sediment properties on the development and dissociation of concentrated hydrate anomalies. To this end, we developed numerical models to predict equilibrium solubility of methane in twophase equilibrium with hydrate as a function of measureable porous medium characteristics. The second project component concerned the evolution of hydrate distribution in heterogeneous reservoirs. To this end, we developed numerical models to predict the growth and decay of anomalies in representative physical environments. The third project component concerned the stability of hydrate-bearing slopes under changing environmental conditions. To this end, we developed numerical treatments of pore pressure evolution and consolidation, then used "infinite-slope" analysis to approximate the landslide potential in representative physical environments, and developed a "rate-and-state" frictional formulation to assess the stability of finite slip patches that are hypothesized to develop in response to the dissociation of hydrate anomalies. The increased predictive capabilities that result from this work provide a framework for interpreting field observations of hydrate anomalies in terms of the history of environmental forcing that led to their development. Moreover

  9. Cryopegs as destabilization factor of intra-permafrost gas hydrates

    Science.gov (United States)

    Chuvilin, Evgeny; Bukhanov, Boris; Istomin, Vladimir

    2016-04-01

    A characteristic feature of permafrost soils in the Arctic is widespread intra-permafrost unfrozen brine lenses - cryopegs. They are often found in permafrost horizons in the north part of Western Siberia, in particular, on the Yamal Peninsula. Cryopegs depths in permafrost zone can be tens and hundreds of meters from the top of frozen strata. The chemical composition of natural cryopegs is close to sea waters, but is characterized by high mineralization. They have a sodium-chloride primary composition with a minor amount of sulphate. Mineralization of cryopegs brine is often hundreds of grams per liter, and the temperature is around -6…-8 °C. The formation of cryopegs in permafrost is associated with processes of long-term freezing of sediments and cryogenic concentration of salts and salt solutions in local areas. The cryopegs' formation can take place in the course of permafrost evolution at the sea transgressions and regressions during freezing of saline sea sediments. Very important feature of cryopegs in permafrost is their transformation in the process of changing temperature and pressure conditions. As a result, the salinity and chemical composition are changed and in addition the cryopegs' location can be changed during their migration. The cryopegs migration violates the thermodynamic conditions of existence intra-permafrost gas hydrate formations, especially the relic gas hydrates deposits, which are situated in the shallow permafrost up to 100 meters depth in a metastable state [1]. The interaction cryopegs with gas hydrates accumulations can cause decomposition of intra-permafrost hydrates. Moreover, the increasing of salt and unfrozen water content in sedimentary rocks sharply reduce the efficiency of gas hydrates self-preservation in frozen soils. It is confirmed by experimental investigations of interaction of frozen gas hydrate bearing sediments with salt solutions [2]. So, horizons with elevated pressure can appear, as a result of gas hydrate

  10. Kinetic modelling of enzyme inactivation Kinetics of heat inactivation of the extracellular proteinase from Pseudomonas fluorescens 22F.

    NARCIS (Netherlands)

    Schokker, E.P.

    1997-01-01

    The kinetics of heat inactivation of the extracellular proteinase from Pseudomonas fluorescens 22F was studied. It was established, by making use of kinetic modelling, that heat inactivation in the temperature range 35 - 70 °C was most likely caused by intermolecular autoproteolysis, where unfolded

  11. Sunlight inactivation of viruses in open-water unit process treatment wetlands: modeling endogenous and exogenous inactivation rates.

    Science.gov (United States)

    Silverman, Andrea I; Nguyen, Mi T; Schilling, Iris E; Wenk, Jannis; Nelson, Kara L

    2015-03-03

    Sunlight inactivation is an important mode of disinfection for viruses in surface waters. In constructed wetlands, for example, open-water cells can be used to promote sunlight disinfection and remove pathogenic viruses from wastewater. To aid in the design of these systems, we developed predictive models of virus attenuation that account for endogenous and exogenous sunlight-mediated inactivation mechanisms. Inactivation rate models were developed for two viruses, MS2 and poliovirus type 3; laboratory- and field-scale experiments were conducted to evaluate the models' ability to estimate inactivation rates in a pilot-scale, open-water, unit-process wetland cell. Endogenous inactivation rates were modeled using either photoaction spectra or total, incident UVB irradiance. Exogenous inactivation rates were modeled on the basis of virus susceptibilities to singlet oxygen. Results from both laboratory- and field-scale experiments showed good agreement between measured and modeled inactivation rates. The modeling approach presented here can be applied to any sunlit surface water and utilizes easily measured inputs such as depth, solar irradiance, water matrix absorbance, singlet oxygen concentration, and the virus-specific apparent second-order rate constant with singlet oxygen (k2). Interestingly, the MS2 k2 in the open-water wetland was found to be significantly larger than k2 observed in other waters in previous studies. Examples of how the model can be used to design and optimize natural treatment systems for virus inactivation are provided.

  12. Properties of samples containing natural gas hydrate from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well, determined using Gas Hydrate And Sediment Test Laboratory Instrument (GHASTLI)

    Science.gov (United States)

    Winters, W.J.

    1999-01-01

    As part of an ongoing laboratory study, preliminary acoustic, strength, and hydraulic conductivity results are presented from a suite of tests conducted on four natural-gas-hydrate-containing samples from the Mackenzie Delta JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well. The gas hydrate samples were preserved in pressure vessels during transport from the Northwest Territories to Woods Hole, Massachusetts, where multistep tests were performed using GHASTLI (Gas Hydrate And Sediment Test Laboratory Instrument), which recreates pressure and temperature conditions that are stable for gas hydrate. Properties and changes in sediment behaviour were measured before, during, and after controlled gas hydrate dissociation. Significant amounts of gas hydrate occupied the sample pores and substantially increased acoustic velocity and shear strength.

  13. Low-δD hydration rinds in Yellowstone perlites record rapid syneruptive hydration during glacial and interglacial conditions

    Science.gov (United States)

    Bindeman, Ilya N.; Lowenstern, Jacob B.

    2016-11-01

    Hydration of silicic volcanic glass forms perlite, a dusky, porous form of altered glass characterized by abundant "onion-skin" fractures. The timing and temperature of perlite formation are enigmatic and could plausibly occur during eruption, during post-eruptive cooling, or much later at ambient temperatures. To learn more about the origin of natural perlite, and to fingerprint the hydration waters, we investigated perlitic glass from several synglacial and interglacial rhyolitic lavas and tuffs from the Yellowstone volcanic system. Perlitic cores are surrounded by a series of conchoidal cracks that separate 30- to 100-µm-thick slivers, likely formed in response to hydration-induced stress. H2O and D/H profiles confirm that most D/H exchange happens together with rapid H2O addition but some smoother D/H variations may suggest separate minor exchange by deuterium atom interdiffusion following hydration. The hydrated rinds (2-3 wt% H2O) transition rapidly (within 30 µm, or by 1 wt% H2O per 10 µm) to unhydrated glass cores. This is consistent with quenched "hydration fronts" where H2O diffusion coefficients are strongly dependent on H2O concentrations. The chemical, δ18O, and δD systematics of bulk glass records last equilibrium between 110 and 60 °C without chemical exchange but with some δ18O exchange. Similarly, the δ18O of water extracted from glass by rapid heating suggests that water was added to the glass during cooling at 400 °C) experimental data. The thick hydration rinds in perlites, measuring hundreds of microns, preserve the original D/H values of hydrating water as a recorder of paleoclimate conditions. Measured δD values in perlitic lavas are -150 to -191 or 20-40 ‰ lower than glass hydrated by modern Yellowstone waters. This suggests that Yellowstone perlites record the low-δD signature of glacial ice. Cooling calculations, combined with the observed high water diffusion coefficients noted for 60-150 °C, suggest that if sufficient hot

  14. Gas Hydrate Research Site Selection and Operational Research Plans

    Science.gov (United States)

    Collett, T. S.; Boswell, R. M.

    2009-12-01

    In recent years it has become generally accepted that gas hydrates represent a potential important future energy resource, a significant drilling and production hazard, a potential contributor to global climate change, and a controlling factor in seafloor stability and landslides. Research drilling and coring programs carried out by the Ocean Drilling Program (ODP), the Integrated Ocean Drilling Program (IODP), government agencies, and several consortia have contributed greatly to our understanding of the geologic controls on the occurrence of gas hydrates in marine and permafrost environments. For the most part, each of these field projects were built on the lessons learned from the projects that have gone before them. One of the most important factors contributing to the success of some of the more notable gas hydrate field projects has been the close alignment of project goals with the processes used to select the drill sites and to develop the project’s operational research plans. For example, IODP Expedition 311 used a transect approach to successfully constrain the overall occurrence of gas hydrate within the range of geologic environments within a marine accretionary complex. Earlier gas hydrate research drilling, including IODP Leg 164, were designed primarily to assess the occurrence and nature of marine gas hydrate systems, and relied largely on the presence of anomalous seismic features, including bottom-simulating reflectors and “blanking zones”. While these projects were extremely successful, expeditions today are being increasingly mounted with the primary goal of prospecting for potential gas hydrate production targets, and site selection processes designed to specifically seek out anomalously high-concentrations of gas hydrate are needed. This approach was best demonstrated in a recently completed energy resource focused project, the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II (GOM JIP Leg II), which featured the collection of a

  15. Kinetic Hydration Heat Modeling for High-Performance Concrete Containing Limestone Powder

    Directory of Open Access Journals (Sweden)

    Xiao-Yong Wang

    2017-01-01

    Full Text Available Limestone powder is increasingly used in producing high-performance concrete in the modern concrete industry. Limestone powder blended concrete has many advantages, such as increasing the early-age strength, reducing the setting time, improving the workability, and reducing the heat of hydration. This study presents a kinetic model for modeling the hydration heat of limestone blended concrete. First, an improved hydration model is proposed which considers the dilution effect and nucleation effect due to limestone powder addition. A degree of hydration is calculated using this improved hydration model. Second, hydration heat is calculated using the degree of hydration. The effects of water to binder ratio and limestone replacement ratio on hydration heat are clarified. Third, the temperature history and temperature distribution of hardening limestone blended concrete are calculated by combining hydration model with finite element method. The analysis results generally agree with experimental results of high-performance concrete with various mixing proportions.

  16. The specific surface area of methane hydrate formed in different conditions and manners

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The specific surface area of methane hydrates, formed both in the presence and absence of sodium dodecyl sulfate (SDS) and processed in different manners (stirring, compacting, holding the hydrates at the formation conditions for different periods of time, cooling the hydrates for different periods of time before depressurizing them), was measured under atmospheric pressure and temperatures below ice point. It was found that the specific surface area of hydrate increased with the decreasing temperature. The methane hydrate in the presence of SDS was shown to be of bigger specific surface areas than pure methane hydrates. The experimental results further demonstrated that the manners of forming and processing hydrates affected the specific surface area of hydrate samples. Stirring or compacting made the hydrate become finer and led to a bigger specific surface area.

  17. A Circuit Model of Real Time Human Body Hydration.

    Science.gov (United States)

    Asogwa, Clement Ogugua; Teshome, Assefa K; Collins, Stephen F; Lai, Daniel T H

    2016-06-01

    Changes in human body hydration leading to excess fluid losses or overload affects the body fluid's ability to provide the necessary support for healthy living. We propose a time-dependent circuit model of real-time human body hydration, which models the human body tissue as a signal transmission medium. The circuit model predicts the attenuation of a propagating electrical signal. Hydration rates are modeled by a time constant τ, which characterizes the individual specific metabolic function of the body part measured. We define a surrogate human body anthropometric parameter θ by the muscle-fat ratio and comparing it with the body mass index (BMI), we find theoretically, the rate of hydration varying from 1.73 dB/min, for high θ and low τ to 0.05 dB/min for low θ and high τ. We compare these theoretical values with empirical measurements and show that real-time changes in human body hydration can be observed by measuring signal attenuation. We took empirical measurements using a vector network analyzer and obtained different hydration rates for various BMI, ranging from 0.6 dB/min for 22.7 [Formula: see text] down to 0.04 dB/min for 41.2 [Formula: see text]. We conclude that the galvanic coupling circuit model can predict changes in the volume of the body fluid, which are essential in diagnosing and monitoring treatment of body fluid disorder. Individuals with high BMI would have higher time-dependent biological characteristic, lower metabolic rate, and lower rate of hydration.

  18. Hydration Properties of Soybean Protein Isolates

    Directory of Open Access Journals (Sweden)

    G. Remondetto

    2001-12-01

    Full Text Available Hydration properties of soybean isolates with different processing conditions (heat treatments, pH and protein concentrations were studied. Degree of denaturation,, solubility in water, in 0.2mol/L NaCl, and in media of different sodium dodecyl sulfate concentrations, viscosity and water imbibing capacity of the different samples were determinated and correlated. Treatments at temperatures higher than 80ºC denatured 11S and 7S proteins, leading to exposure of hydrophobic groups, which produced insoluble aggregates either in water or in high ionic strength media. These isolates possessed high water imbibing capacities and gave rise to viscous dispersions. Significant correlations were obtained between hydration properties and the "m" coefficient as calculated by a power law equation relating viscosity with the protein concentration of the dispersion. This "m" coefficient also correlated with the denaturation enthalpy of the protein isolates. On the basis of these results, it might be suggested that the "m" coefficient - dependent of the hydrodynamic behaviour of the particles - was a good estimator of the degree of protein denaturation.Estudaram-se as propriedades de hidratação de isolados de soja com diferentes condições de procesamento (tratamentos térmicos, pH e concentração de proteínas. Para diferentes amostras determinaram-se e correlacionaram-se o gráu de desnaturalização, a solubilidade em água, em 0,2mol/L NaCl e em diferentes concentrações de dodecil sulfato de sódio, viscosidade e capacidade de absorção de água. Os tratamentos a temperaturas superiores aos 80ºC desnaturaram as fracções 11S e 7S, provocando a exposição de grupos hidrofóbicos os que produziram agregados insolúveis, em água como em solução com alta força iónica. Estes isolados posuiam alta capacidade de absorção de água e dispersões com alta viscosidade. Achou-se uma correlação significativa entre as propriedades de hidratação e o

  19. Estimation of gas hydrate saturation with temperature calculated from hydrate threshold at C0002 during IODP NanTroSEIZE Stage 1 expeditions in the Nankai Trough

    Science.gov (United States)

    Miyakawa, A.; Yamada, Y.; Saito, S.; Bourlange, S.; Chang, C.; Conin, M.; Tomaru, H.; Kinoshita, M.; Tobin, H.; 314/315/316Scientists, E.

    2008-12-01

    During the IODP Expedition 314, conducted at Nankai trough accretionary prism, gas hydrate was observed at Site C0002. Gas hydrate beneath seafloor is promising energy source and potentially hazardous material during drilling. The precise estimation of gas hydrate saturation is important, but previous works have not considered the effect" of the in-situ temperature. In this study, we propose an estimation method of gas hydrate saturation with temperature calculated from threshold of gas hydrate. Gas hydrate saturation was determined based on the Logging While Drilling (LWD) Expedition 314 data. The gas hydrate bearing zone was located between 218.1 to 400.4 m below seafloor. Archie's relation was used to estimate gas hydrate saturation. This relation requires the porosity, the sea water resistivity and formation resistivity. We determined porosity to be between ~70 to ~30% based on density log. Since the resistivity of sea water is temperature dependent, temperature profile (calculated temperature model) was determined from the thermal conductivity and the temperature at the base of the gas hydrate. In our calculated temperature model, the saturation increases from ~10% at ~220m to ~30% at 400 m below sea floor. Spikes that have a maximum value at 80% at sand layers were observed. We also estimated the gas hydrate saturation from the constant temperature profile in 12°C (temperature constant model). This resulted in almost constant saturation (~15%) with the high saturation spikes. We compared these saturations with the hydrate occupation ratio within sand layers derived from RAB image. The hydrate occupation ratio shows increasing trend with increasing depth, and this trend is similar to the gas hydrate saturation with the calculated temperature model. This result suggests that the temperature profile should be considered to obtain precise gas hydrate saturation. Since the high sedimentation rate can affect thermal condition, we are planning to estimate the

  20. Theoretical and computational studies of hydrophobic and hydrophilic hydration: Towards a molecular description of the hydration of proteins

    Science.gov (United States)

    Garde, Shekhar

    The unique balance of forces underlying biological processes-such as protein folding, aggregation, molecular recognition, and the formation of biological membranes-owes its origin in large part to the surrounding aqueous medium. A quantitative description of fundamental noncovalent interactions, in particular hydrophobic and electrostatic interactions at molecular- scale separations, requires an accurate description of water structure. Thus, the primary goals of our research are to understand the role of water in mediating interactions between molecules and to incorporate this understanding into molecular theories for calculating water-mediated interactions. We have developed a molecular model of hydrophobic interactions that uses methods of information theory to relate hydrophobic effects to the density fluctuations in liquid water. This model provides a quantitative description of small-molecule hydration thermodynamics, as well as insights into the entropies of unfolding globular proteins. For larger molecular solutes, we relate the inhomogeneous water structure in their vicinity to their hydration thermodynamics. We find that the water structure in the vicinity of nonpolar solutes is only locally sensitive to the molecular details of the solute. Water structures predicted using this observation are used to study the association of two neopentane molecules and the conformational equilibria of n-pentane molecule. We have also studied the hydration of a model molecular ionic solute, a tetramethylammonium ion, over a wide range of charge states of the solute. We find that, although the charge dependence of the ion hydration free energy is quadratic, negative ions are more favorably hydrated compared to positive ions. Moreover, this asymmetry of hydration can be reconciled by considering the differences in water organization surrounding positive and negative ions. We have also developed methods for predicting water structure surrounding molecular ions and relating

  1. The Water Retention Curves in THF Hydrate-Bearing Sediments - Experimental Measurement and Pore Scale Simulation

    Science.gov (United States)

    Mahabadi, N.; Zheng, X.; Dai, S.; Seol, Y.; Zapata, C.; Yun, T.; Jang, J.

    2015-12-01

    The water retention curve (WRC) of hydrate-bearing sediments is critically important to understand the behaviour of hydrate dissociation for gas production. Most gas hydrates in marine environment have been formed from an aqueous phase (gas-dissolved water). However, the gas hydrate formation from an aqueous phase in a laboratory requires long period due to low gas solubility in water and is also associated with many experimental difficulties such as hydrate dissolution, difficult hydrate saturation control, and dynamic hydrate dissolution and formation. In this study, tetrahydrofuran (THF) is chosen to form THF hydrate because the formation process is faster than gas hydrate formation and hydrate saturation is easy to control. THF hydrate is formed at water-excess condition. Therefore, there is only water in the pore space after a target THF hydrate saturation is obtained. The pore habit of THF hydrate is investigated by visual observation in a transparent micromodel and X-ray computed tomography images; and the water retention curves are obtained under different THF hydrate saturation conditions. Targeted THF hydrate saturations are Sh=0, 0.2, 0.4, 0.6 and 0.8. Results shown that at a given water saturation the capillary pressure increases as THF hydrate saturation increases. And the gas entry pressure increases with increasing hydrate saturation. The WRC obtained by experiments is also compared with the results of a pore-network model simulation and Lattice Boltzmann Method. The fitting parameters of van Genuchten equation for different hydrate saturation conditions are suggested for the use as input parameters of reservoir simulators.

  2. Inactivation of Lassa, Marburg, and Ebola viruses by gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, L.H.; McCormick, J.B.; Johnson, K.M.

    1982-10-01

    Because of the cumbersome conditions experienced in a maximum containment laboratory, methods for inactivating highly pathogenic viruses were investigated. The infectivity of Lassa, Marburg, and Ebola viruses was inactivated without altering the immunological activity after radiation with /sup 60/Co gamma rays. At 4 degrees C, Lassa virus was the most difficult to inactivate with a rate of 5.3 X 10(-6) log 50% tissue culture infective dose per rad of /sup 60/Co radiation, as compared with 6.8 X 10(-6) log 50% tissue culture infective dose per rad for Ebola virus and 8.4 X 10(-6) log 50% tissue culture infective dose per rad for Marburg virus. Experimental inactivation curves, as well as curves giving the total radiation needed to inactivate a given concentration of any of the three viruses, are presented. We found this method of inactivation to be superior to UV light or beta-propiolactone inactivation and now routinely use it for preparation of material for protein-chemistry studies or for preparation of immunological reagents.

  3. Inactivation of Lassa, Marburg, and Ebola viruses by gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, L.H.; McCormick, J.B.; Johnson, K.M.

    1982-10-01

    Because of the cumbersome conditions experienced in a maximum containment laboratory, methods for inactivating highly pathogenic viruses were investigated. The infectivity of Lassa, Marburg, and Ebola viruses was inactivated without altering the immunological activity after radiation with /sup 60/CO gamma rays. At 4 degrees C, Lassa virus was the most difficult to inactivate with a rate of 5.3 X 10(-6) log 50% tissue culture infective dose per rad of /sup 60/CO radiation, as compared with 6.8 X 10(-6) log 50% tissue culture infective dose per rad for Ebola virus and 8.4 X 10(-6) log 50% tissue culture infective dose per rad for Marburg virus. Experimental inactivation curves, as well as curves giving the total radiation needed to inactivate a given concentration of any of the three viruses, are presented. The authors found this method of inactivation to be superior to UV light or beta-propiolactone inactivation and now routinely use it for preparation of material for protein-chemistry studies or for preparation of immunological reagents.

  4. Virus-specific thermostability and heat inactivation profiles of alphaviruses.

    Science.gov (United States)

    Park, So Lee; Huang, Yan-Jang S; Hsu, Wei-Wen; Hettenbach, Susan M; Higgs, Stephen; Vanlandingham, Dana L

    2016-08-01

    Serological diagnosis is a critical component for disease surveillance and is important to address the increase in incidence and disease burden of alphaviruses, such as the chikungunya (CHIKV) and Ross River (RRV) viruses. The gold standard for serological diagnosis is the plaque reduction neutralization test (PRNT), which demonstrates the neutralizing capacity of serum samples after the removal of complement activity and adventitious viruses. This procedure is normally performed following inactivation of the virus at 56°C for 30min. Although this protocol has been widely accepted for the inactivation of envelope RNA viruses, recent studies have demonstrated that prolonged heat inactivation is required to completely inactivate two alphaviruses, Western equine encephalitis virus and CHIKV. Incomplete inactivation of viruses poses a laboratory biosafety risk and can also lead to spurious test results. Despite its importance in ensuring the safety of laboratory personnel as well as test integrity, systematic investigation on the thermostability of alphaviruses has not been performed. In this study, the temperature tolerance and heat inactivation profiles of RRV, Barmah Forest, and o'nyong-nyong viruses were determined. Variations in thermostability were observed within the Semliki forest serocomplex. Therefore, evidence-based heat inactivation procedures for alphaviruses are recommended.

  5. X chromosome inactivation and X-linked mental retardation

    Energy Technology Data Exchange (ETDEWEB)

    Willard, H.F. [Case Western Reserve Univ. School of Medicine, Cleveland, OH (United States)]|[Univ. Hospitals of Cleveland, OH (United States)

    1996-07-12

    The expression of X-linked genes in females heterozygous for X-linked defects can be modulated by epigenetic control mechanisms that constitute the X chromosome inactivation pathway. At least four different effects have been found to influence, in females, the phenotypic expression of genes responsible for X-linked mental retardation (XLMR). First, non-random X inactivation, due either to stochastic or genetic factors, can result in tissues in which one cell type (for example, that in which the X chromosome carrying a mutant XLMR gene is active) dominates, instead of the normal mosaic cell population expected as a result of random X inactivation. Second, skewed inactivation of the normal X in individuals carrying a deletion of part of the X chromosome has been documented in a number of mentally retarded females. Third, functional disomy of X-linked genes that are expressed inappropriately due to the absence of X inactivation has been found in mentally retarded females with structurally abnormal X chromosomes that do not contain the X inactivation center. And fourth, dose-dependent overexpression of X-linked genes that normally {open_quotes}escape{close_quotes} X inactivation may account for the mental and developmental delay associated with increasing numbers of otherwise inactive X chromosomes in individuals with X chromosome aneuploidy. 53 refs., 1 fig.

  6. Tectonic Controls on Gas Hydrate Distribution off SW Taiwan

    Science.gov (United States)

    Berndt, C.; Chi, W. C.; Jegen, M. D.; Muff, S.; Hölz, S.; Lebas, E.; Sommer, M.; Lin, S.; Liu, C. S.; Lin, A. T.; Klaucke, I.; Klaeschen, D.; Chen, L.; Kunath, P.; McIntosh, K. D.; Feseker, T.

    2015-12-01

    The northern part of the South China Sea is characterized by wide-spread occurrence of bottom simulating reflectors (BSR), indicating the presence of marine gas hydrates. Because the area covers both the tectonically inactive passive margin and the northern termination of the Manila Trench subduction zone while sediment input is broadly similar, this area provides an excellent opportunity to study the influence of tectonic processes on the dynamics of gas hydrate systems. Long-offset multi-channel seismic data show that movement along thrust faults and blind thrust faults caused anticlinal ridges on the active margin, while faults are absent on the passive margin. This coincides with high-hydrate saturations derived from ocean bottom seismometer data and controlled source electromagnetic data, and conspicuous high-amplitude reflections in P-Cable 3D seismic data above the BSR in the anticlinal ridges of the active margin. On the contrary, all geophysical evidence for the passive margin points to normal- to low-hydrate saturations. Geochemical analysis of gas samples collected at seep sites on the active margin show methane with heavy δ13C isotope composition, while gas collected on the passive margin shows highly depleted (light) carbon isotope composition. Thus, we interpret the passive margin as a typical gas hydrate province fuelled by biogenic production of methane and the active margin gas hydrate system as a system that is fuelled not only by biogenic gas production but also by additional advection of thermogenic methane from the subduction system. The location of the highest gas hydrate saturations in the hanging wall next to the thrust faults suggests that the thrust faults represent pathways for the migration of methane. Our findings suggest that the most promising gas hydrate occurrences for exploitation of gas hydrate as an energy source may be found in the core of the active margin roll over anticlines immediately above the BSR and that high

  7. Opto-thermal in-vivo skin hydration measurements - a comparison study of different measurement techniques

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, P; Singh, H; Imhof, R E [Faculty of ESBE, London South Bank University, 103 Borough Road, London SE1 0AA (United Kingdom); Ciortea, L I; Berg, E P [Biox Systems Ltd, 103 Borough Road, London SE1 0AA (United Kingdom); Cui, Y, E-mail: xiaop@lsbu.ac.u [Sunrise Systems Limited, Flint Bridge Business Centre, Ely Road, Waterbeach, Cambridge CB5 9QZ (United Kingdom)

    2010-03-01

    We compared five different skin hydration measurement techniques, namely OTTER, Fingerprint sensors, Corneometer, Nova, and Moisture Checker, in order to understand the correlations between different skin hydration measurement techniques and to understand the repeatability of each technique. The measurements are performed on different in-vivo skin sites from different volunteers and at different hydration levels. The repeatability of different techniques is achieved by measuring the same skin site repeatedly. The correlations between different skin hydration measurement techniques are achieved by plotting results from different techniques against each other. The different skin hydration levels are achieved through the recovery period after a skin immersive hydration.

  8. Controls on evolution of gas-hydrate system in the Krishna-Godavari basin, offshore India

    Digital Repository Service at National Institute of Oceanography (India)

    Badesab, F.K.; Dewangan, P.; Usapkar, A.; Kocherla, M.; Peketi, A.; Mohite, K.; Sangode, S.J.; Deenadayalan, K.

    magnetic minerals in the studied samples. 5.5. Can magnetic record be used as a potential tracer to identify the fossil gas hydrate zone in the K-G basin? In marine settings, the dissociation of gas hydrates takes place whenever P-T condition changes..., whenever the suitable P-T conditions prevail, hydrate nucleation takes place leaving the former boundary of gas hydrate stability zone (GHSZ) as a fossil gas hydrate horizon. In K-G basin, the present base of GHSZ calculated using hydrate stability...

  9. Hydration study of ordinary portland cement in the presence of zinc ions

    Directory of Open Access Journals (Sweden)

    Monica Adriana Trezza

    2007-12-01

    Full Text Available Hydration products of Portland cement pastes, hydrated in water and in the presence of zinc ions were studied comparatively at different ages. Hydration products were studied by X ray diffractions (XRD and infrared spectroscopy (IR. Although IR is not frequently used in cement chemistry, it evidenced a new phase Ca(Zn(OH32. 2H2O formed during cement hydration in the presence of zinc. The significant retardation of early cement hydration in the presence of zinc is assessed in detail by differential calorimetry as a complement to the study carried out by IR and XRD, providing evidence that permits to evaluate the kinetic of the early hydration.

  10. Integrating Natural Gas Hydrates in the Global Carbon Cycle

    Energy Technology Data Exchange (ETDEWEB)

    David Archer; Bruce Buffett

    2011-12-31

    We produced a two-dimensional geological time- and basin-scale model of the sedimentary margin in passive and active settings, for the simulation of the deep sedimentary methane cycle including hydrate formation. Simulation of geochemical data required development of parameterizations for bubble transport in the sediment column, and for the impact of the heterogeneity in the sediment pore fluid flow field, which represent new directions in modeling methane hydrates. The model is somewhat less sensitive to changes in ocean temperature than our previous 1-D model, due to the different methane transport mechanisms in the two codes (pore fluid flow vs. bubble migration). The model is very sensitive to reasonable changes in organic carbon deposition through geologic time, and to details of how the bubbles migrate, in particular how efficiently they are trapped as they rise through undersaturated or oxidizing chemical conditions and the hydrate stability zone. The active margin configuration reproduces the elevated hydrate saturations observed in accretionary wedges such as the Cascadia Margin, but predicts a decrease in the methane inventory per meter of coastline relative to a comparable passive margin case, and a decrease in the hydrate inventory with an increase in the plate subduction rate.

  11. Behavior of calcium silicate hydrate in aluminate solution

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-bin; ZHAO Zhuo; LIU Gui-hua; ZHOU Qiu-sheng; PENG Zhi-hong

    2005-01-01

    Using calcium hydroxide and sodium silicate as starting materials, two kinds of calcium silicate hydrates, CaO · SiO2 · H2O and 2CaO · SiO2 · 1.17H2O, were hydro-thermally synthesized at 120 ℃. The reaction rule of calcium silicate hydrate in aluminate solution was investigated. The result shows that CaO · SiO2 · H2O is more stable than 2CaO · SiO2 · 1.17H2 O in aluminate solution and its stability increases with the increase of reaction temperature but decreases with the increase of caustic concentration. The reaction between calcium silicate hydrate and aluminate solution is mainly through two routes. In the first case, Al replaces partial Si in calcium silicate hydrate, meanwhile 3CaO · Al2 O3 · xSiO2 · (6-2x) H2 O (hydro-garnet) is formed and some SiO2 enters the solution. In the second case, calcium silicate hydrate can react directly with aluminate solution, forming hydro-garnet and Na2O · Al2O3 · 2SiO2 · nH2O (DSP). The desilication reaction of aluminate solution containing silicate could contribute partially to forming DSP.

  12. Gas Hydrate Research Database and Web Dissemination Channel

    Energy Technology Data Exchange (ETDEWEB)

    Micheal Frenkel; Kenneth Kroenlein; V Diky; R.D. Chirico; A. Kazakow; C.D. Muzny; M. Frenkel

    2009-09-30

    To facilitate advances in application of technologies pertaining to gas hydrates, a United States database containing experimentally-derived information about those materials was developed. The Clathrate Hydrate Physical Property Database (NIST Standard Reference Database {number_sign} 156) was developed by the TRC Group at NIST in Boulder, Colorado paralleling a highly-successful database of thermodynamic properties of molecular pure compounds and their mixtures and in association with an international effort on the part of CODATA to aid in international data sharing. Development and population of this database relied on the development of three components of information-processing infrastructure: (1) guided data capture (GDC) software designed to convert data and metadata into a well-organized, electronic format, (2) a relational data storage facility to accommodate all types of numerical and metadata within the scope of the project, and (3) a gas hydrate markup language (GHML) developed to standardize data communications between 'data producers' and 'data users'. Having developed the appropriate data storage and communication technologies, a web-based interface for both the new Clathrate Hydrate Physical Property Database, as well as Scientific Results from the Mallik 2002 Gas Hydrate Production Research Well Program was developed and deployed at http://gashydrates.nist.gov.

  13. State of hydration and electrical conductance of ichthyotic skin

    Directory of Open Access Journals (Sweden)

    Gupta A

    1990-01-01

    Full Text Available Dry skin of twelve subjects suffering from ichthyosis vulgaris and the efficacy of a moisturiser-Cotaryl were quantitatively assessed by measuring the skin surface hydration and high frequency (3.5 MHz electrical conductance of skin. The state of hydration and conductance of ichthyotic skin were 86.9 + 24.6 and 11.0 + 5.7 micro-mho respectively, being much less-compared to 132. 0 + 5.3 and 72.5 + 54.0 micro-mho ofnormal subjects. The moisturiser increased the state of hydration and also the electrical conductance of the stratum corneuni to near-normal values and maintained them as long as the application continued. However, both the hydration and the conductance fell sharply within a week of withrawal of the moisturiser. A moisturiser was thus undoubtedly efficacious in ichthyotic skin, but the effect was only temporary. The state of hydration was found, at all stages, to bear a strong positive correlation (r = 0.69 to 0.80 with the skin conductance.

  14. Acoustical method of whole-body hydration status monitoring

    Science.gov (United States)

    Sarvazyan, A. P.; Tsyuryupa, S. N.; Calhoun, M.; Utter, A.

    2016-07-01

    An acoustical handheld hydration monitor (HM) for assessing the water balance of the human body was developed. Dehydration is a critical public health problem. Many elderly over age of 65 are particularly vulnerable as are infants and young children. Given that dehydration is both preventable and reversible, the need for an easy-to-perform method for the detection of water imbalance is of the utmost clinical importance. The HM is based on an experimental fact that ultrasound velocity in muscle is a linear function of water content and can be referenced to the hydration status of the body. Studies on the validity of HM for the assessment of whole-body hydration status were conducted in the Appalachian State University, USA, on healthy young adults and on elderly subjects residing at an assisted living facility. The HM was able to track changes in total body water during periods of acute dehydration and rehydration in athletes and day-to-day and diurnal variability of hydration in elderly. Results of human studies indicate that HM has a potential to become an efficient tool for detecting abnormal changes in the body hydration status.

  15. Hydration status affects osteopontin expression in the rat kidney.

    Science.gov (United States)

    Lee, Su-Youn; Lee, Sae-Jin; Piao, Hong-Lin; Yang, Suk-Young; Weiner, I David; Kim, Jin; Han, Ki-Hwan

    2016-09-30

    Osteopontin (OPN) is a secretory protein that plays an important role in urinary stone formation. Hydration status is associated with the development of urolithiasis. This study was conducted to examine the effects of dehydration and hydration on OPN expression in the rat kidney. Animals were divided into three groups, control, dehydrated, and hydrated. Kidney tissues were processed for light and electron microscope immunocytochemistry, in situhybridization, and immunoblot analysis. Dehydration induced a significant increase in OPN protein expression, whereas increased fluid intake induced a decrease in protein expression. Under control conditions, OPN protein and mRNA expression were only detected in the descending thin limb (DTL). Dehydration induced increased expression in the DTL and the development of detectable expression in the thick ascending limb (TAL). In contrast, OPN expression levels declined to less than the controls in the DTL after hydration, while no expression of either protein or mRNA was detectable in the TAL. Immunoelectron microscopy demonstrated that hydration status altered tubular ultrastructure and intracellular OPN expression in the Golgi apparatus and secretory cytoplasmic vesicles. These data confirm that changes in oral fluid intake can regulate renal tubular epithelial cell OPN expression.

  16. Structural stability of methane hydrate at high pressures

    Science.gov (United States)

    Shu, J.; Chen, X.; Chou, I.-Ming; Yang, W.; Hu, Jiawen; Hemley, R.J.; Mao, Ho-kwang

    2011-01-01

    The structural stability of methane hydrate under pressure at room temperature was examined by both in-situ single-crystal and powder X-ray diffraction techniques on samples with structure types I, II, and H in diamond-anvil cells. The diffraction data for types II (sII) and H (sH) were refined to the known structures with space groups Fd3m and P63/mmc, respectively. Upon compression, sI methane hydrate transforms to the sII phase at 120 MPa, and then to the sH phase at 600 MPa. The sII methane hydrate was found to coexist locally with sI phase up to 500 MPa and with sH phase up to 600 MPa. The pure sH structure was found to be stable between 600 and 900 MPa. Methane hydrate decomposes at pressures above 3 GPa to form methane with the orientationally disordered Fm3m structure and ice VII (Pn3m). The results highlight the role of guest (CH4)-host (H2O) interactions in the stabilization of the hydrate structures under pressure. ?? 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

  17. Hydrate prevention in petroleum production sub sea system

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Paula L.F.; Rocha, Humberto A.R. [Universidade Estacio de Sa (UNESA), Rio de Janeiro, RJ (Brazil); Rodrigues, Antonio P. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2012-07-01

    In spite of the merits of the several hydrate prevention techniques used nowadays, such as: chemical product injection for inhibition and use of thick thermal insulate lines; hydrates per times happen and they are responsible for considerable production losses. Depressurization techniques can be used so much for prevention as in the remediation. Some hydrate removal techniques need a rig or vessel, resources not readily available and with high cost, reason that limits such techniques just for remediation and not for prevention. In the present work it is proposed and described an innovative depressurization system, remote and resident, for hydrate prevention and removal, applicable as for individual sub sea wells as for grouped wells by manifold. Based on low cost jet pumps, without movable parts and with a high reliability, this technique allows hydrate prevention or remediation in a fast and remote way, operated from the production unit. The power fluid line and fluid return line can be integrated in the same umbilical or annulus line structure, without significant increase in the construction costs and installation. It is not necessary to wait for expensive resource mobilization, sometimes not available quickly, such as: vessels or rigs. It still reduces the chemical product consumption and permits to depressurized stopped lines. Other additional advantage, depressurization procedure can be used in the well starting, removing fluid until riser emptying. (author)

  18. Stability Analysis of Methane Hydrate-Bearing Soils Considering Dissociation

    Directory of Open Access Journals (Sweden)

    Hiromasa Iwai

    2015-06-01

    Full Text Available It is well known that the methane hydrate dissociation process may lead to unstable behavior such as large ground deformations, uncontrollable gas production, etc. A linear instability analysis was performed in order to investigate which variables have a significant effect on the onset of the instability behavior of methane hydrate-bearing soils subjected to dissociation. In the analysis a simplified viscoplastic constitutive equation is used for the soil sediment. The stability analysis shows that the onset of instability of the material system mainly depends on the strain hardening-softening parameter, the degree of strain, and the permeability for water and gas. Then, we conducted a numerical analysis of gas hydrate-bearing soil considering hydrate dissociation in order to investigate the effect of the parameters on the system. The simulation method used in the present study can describe the chemo-thermo-mechanically coupled behaviors such as phase changes from hydrates to water and gas, temperature changes and ground deformation. From the numerical results, we found that basically the larger the permeability for water and gas is, the more stable the simulation results are. These results are consistent with those obtained from the linear stability analysis.

  19. Modeling the influence of limestone addition on cement hydration

    Directory of Open Access Journals (Sweden)

    Ashraf Ragab Mohamed

    2015-03-01

    Full Text Available This paper addresses the influence of using Portland limestone cement “PLC” on cement hydration by characterization of its microstructure development. The European Standard EN 197-1:2011 and Egyptian specification ESS 4756-1/2009 permit the cement to contain up to 20% ground limestone. The computational tools assist in better understanding the influence of limestone additions on cement hydration and microstructure development to facilitate the acceptance of these more economical and ecological materials. μic model has been developed to enable the modeling of microstructural evolution of cementitious materials. In this research μic model is used to simulate both the influence of limestone as fine filler, providing additional surfaces for the nucleation and growth of hydration products. Limestone powder also reacts relatively slow with hydrating cement to form monocarboaluminate (AFmc phase, similar to the mono-sulfoaluminate (AFm phase formed in ordinary Portland cement. The model results reveal that limestone cement has accelerated cement hydration rate, previous experimental results and computer model “cemhyd3d” are used to validate this model.

  20. Mechanisms of inactivation of poliovirus by chlorine dioxide and iodine.

    OpenAIRE

    Alvarez, M.E.; O'Brien, R.T.

    1982-01-01

    Chlorine dioxide and iodine inactivated poliovirus more efficiently at pH 10.0 than at pH 6.0. Sedimentation analyses of viruses inactivated by chlorine dioxide and iodine at pH 10.9 showed that viral RNA separated from the capsids, resulting in the conversion of virions from 156S structures to 80S particles. The RNAs release from both chlorine dioxide- and iodine-inactivated viruses cosedimented with intact 35S viral RNA. Both chlorine dioxide and iodine reacted with the capsid proteins of p...

  1. Inactivation of human and simian rotaviruses by ozone

    Energy Technology Data Exchange (ETDEWEB)

    Vaughn, J.M.; Chen, Y.S.; Lindburg, K.; Morales, D.

    1987-09-01

    The inactivation of simian rotavirus Sa-11 and human rotavirus type 2 (Wa) by ozone was compared at 4/sup 0/C by using single-particle virus stocks. Although the human strain was clearly more sensitive, both virus types were rapidly inactivated by ozone concentrations of 0.25 mg/liter or greater at all pH levels tested. Comparison of the virucidal activity of ozone with that of chlorine in identical experiments indicated little significant difference in rotavirus-inactivating efficiencies when the disinfectants were used at concentrations of 0.25 mg/liter or greater.

  2. Inactivation of the biofilm by the air plasma containing water

    Science.gov (United States)

    Suganuma, Ryota; Yasuoka, Koichi; Yasuoka Takeuchi lab Team

    2014-10-01

    Biofilms are caused by environmental degradation in food factory and medical facilities. Inactivation of biofilm has the method of making it react to chemicals including chlorine, hydrogen peroxide, and ozone. Although inactivation by chemicals has the problem that hazardous property of a residual substance and hydrogen peroxide have slow reaction velocity. We achieved advanced oxidation process (AOP) with air plasma. Hydrogen peroxide and ozone, which were used for the formation of OH radicals in our experiment, were able to be generated selectively by adjusting the amount of water supplied to the plasma. We inactivated Pseudomonas aeruginosa biofilm in five minutes with OH radicals generated by using hydrogen peroxide and ozone.

  3. Methane Hydrate Field Program. Development of a Scientific Plan for a Methane Hydrate-Focused Marine Drilling, Logging and Coring Program

    Energy Technology Data Exchange (ETDEWEB)

    Collett, Tim [U.S. Geological Survey, Boulder, CO (United States); Bahk, Jang-Jun [Korea Inst. of Geoscience and Mineral Resources, Daejeon (Korea); Frye, Matt [U.S. Bureau of Ocean Energy Management, Sterling, VA (United States); Goldberg, Dave [Lamont-Doherty Earth Observatory, Palisades, NY (United States); Husebo, Jarle [Statoil ASA, Stavenger (Norway); Koh, Carolyn [Colorado School of Mines, Golden, CO (United States); Malone, Mitch [Texas A & M Univ., College Station, TX (United States); Shipp, Craig [Shell International Exploration and Production Inc., Anchorage, AK (United States); Torres, Marta [Oregon State Univ., Corvallis, OR (United States); Myers, Greg [Consortium For Ocean Leadership Inc., Washington, DC (United States); Divins, David [Consortium For Ocean Leadership Inc., Washington, DC (United States); Morell, Margo [Consortium For Ocean Leadership Inc., Washington, DC (United States)

    2013-12-31

    This topical report represents a pathway toward better understanding of the impact of marine methane hydrates on safety and seafloor stability and future collection of data that can be used by scientists, engineers, managers and planners to study climate change and to assess the feasibility of marine methane hydrate as a potential future energy resource. Our understanding of the occurrence, distribution and characteristics of marine methane hydrates is incomplete; therefore, research must continue to expand if methane hydrates are to be used as a future energy source. Exploring basins with methane hydrates has been occurring for over 30 years, but these efforts have been episodic in nature. To further our understanding, these efforts must be more regular and employ new techniques to capture more data. This plan identifies incomplete areas of methane hydrate research and offers solutions by systematically reviewing known methane hydrate “Science Challenges” and linking them with “Technical Challenges” and potential field program locations.

  4. A DFT-based comparative equilibrium study of thermal dehydration and hydrolysis of CaCl₂ hydrates and MgCl₂ hydrates for seasonal heat storage.

    Science.gov (United States)

    Pathak, Amar Deep; Nedea, Silvia; Zondag, Herbert; Rindt, Camilo; Smeulders, David

    2016-04-21

    Salt hydrates store solar energy in chemical form via a reversible dehydration-hydration reaction. However, as a side reaction to dehydration, hydrolysis (HCl formation) may occur in chloride based salt hydrates (specially in MgCl2 hydrates), affecting the durability of the storage system. The mixture of CaCl2 and MgCl2 hydrates has been shown experimentally to have exceptional cycle stability and improved kinetics. However, the optimal operating conditions for the mixture are unknown. To understand the appropriate balance between dehydration and hydrolysis kinetics in the mixtures, it is essential to gain in-depth insight into the mixture components. We present a GGA-DFT level study to investigate the various gaseous structures of CaCl2 hydrates and to understand the relative stability of their conformers. The hydration strength and relative stability of conformers are dominated by electrostatic interactions. A wide network of intramolecular homonuclear and heteronuclear hydrogen bonds is observed in CaCl2 hydrates. Equilibrium product concentrations are obtained during dehydration and hydrolysis reactions under various temperature and pressure conditions. The trend of the dehydration curve with temperature in CaCl2 hydrates is similar to the experiments. Comparing these results to those of MgCl2 hydrates, we find that CaCl2 hydrates are more resistant towards hydrolysis in the temperature range of 273-800 K. Specifically, the present study reveals that the onset temperatures of HCl formation, a crucial design parameter for MgCl2 hydrates, are lower than for CaCl2 hydrates except for the mono-hydrate.

  5. Study of Electron Ionization and Fragmentation of Non-hydrated and Hydrated Tetrahydrofuran Clusters

    Science.gov (United States)

    Neustetter, Michael; Mahmoodi-Darian, Masoomeh; Denifl, Stephan

    2017-03-01

    Mass spectroscopic investigations on tetrahydrofuran (THF, C4H8O), a common model molecule of the DNA-backbone, have been carried out. We irradiated isolated THF and (hydrated) THF clusters with low energy electrons (electron energy 70 eV) in order to study electron ionization and ionic fragmentation. For elucidation of fragmentation pathways, deuterated TDF (C4D8O) was investigated as well. One major observation is that the cluster environment shows overall a protective behavior on THF. However, also new fragmentation channels open in the cluster. In this context, we were able to solve a discrepancy in the literature about the fragment ion peak at mass 55 u in the electron ionization mass spectrum of THF. We ascribe this ion yield to the fragmentation of ionized THF clusters.

  6. Investigation of hydrate formation and transportability in multiphase flow systems

    Science.gov (United States)

    Grasso, Giovanny A.

    The oil and gas industry is moving towards offshore developments in more challenging environments, where evaluating hydrate plugging risks to avoid operational/safety hazards becomes more difficult (Sloan, 2005). Even though mechanistic models for hydrate plug formation have been developed, components for a full comprehensive model are still missing. Prior to this work, research efforts were focused on flowing hydrate particles with relatively little research on hydrate accumulation, leaving hydrate deposition in multiphase flow an unexplored subject. The focus of this thesis was to better understand hydrate deposition as a form of accumu- lation in pipelines. To incorporate the multiphase flow effect, hydrate formation experiments were carried out at varying water cut (WC) from 15 to 100 vol.%, liquid loading (LL) from 50 to 85 vol.%, mixture velocity (vmix) from 0.75 to 3 m/s, for three fluids systems (100 % WC, water in Conroe crude oil emulsions and King Ranch condensate + water) on the ExxonMobil flowloop (4 in. nominal size and 314 ft. long) at Friendswood, TX. For the 100 % WC flowloop tests, hydrate particle distribution transitions beyond a critical hydrate volume concentration, observed values were between 8.2 to 29.4 vol.%, causing a sudden increase in pressure drop (DP). A revised correlation of the transition as a function of Reynolds number and liquid loading was developed. For Conroe emulsions, DP starts increasing at higher hydrate concentrations than King Ranch condensate, many times at 10 vol.%. Experiments with King Ranch show higher relative DP (10 to 25) than Conroe (2 to 10) performed at the same vmix and LL. Cohesive force measurements between cyclopentane hydrate particles were reduced from a value of 3.32 mN/m to 1.26 mN/m when 6 wt.% Conroe was used and to 0.41 mN/m when 5 wt.% Caratinga crude oil was used; similar values were obtained when extracted asphaltenes were used. King Ranch condensate (11 wt.%) did not significantly change the

  7. Simulation of gas hydrate dissociation caused by repeated tectonic uplift events

    Science.gov (United States)

    Goto, Shusaku; Matsubayashi, Osamu; Nagakubo, Sadao

    2016-05-01

    Gas hydrate dissociation by tectonic uplift is often used to explain geologic and geophysical phenomena, such as hydrate accumulation probably caused by hydrate recycling and the occurrence of double bottom-simulating reflectors in tectonically active areas. However, little is known of gas hydrate dissociation resulting from tectonic uplift. This study investigates gas hydrate dissociation in marine sediments caused by repeated tectonic uplift events using a numerical model incorporating the latent heat of gas hydrate dissociation. The simulations showed that tectonic uplift causes upward movement of some depth interval of hydrate-bearing sediment immediately above the base of gas hydrate stability (BGHS) to the gas hydrate instability zone because the sediment initially maintains its temperature: in that interval, gas hydrate dissociates while absorbing heat; consequently, the temperature of the interval decreases to that of the hydrate stability boundary at that depth. Until the next uplift event, endothermic gas hydrate dissociation proceeds at the BGHS using heat mainly supplied from the sediment around the BGHS, lowering the temperature of that sediment. The cumulative effects of these two endothermic gas hydrate dissociations caused by repeated uplift events lower the sediment temperature around the BGHS, suggesting that in a marine area in which sediment with a highly concentrated hydrate-bearing layer just above the BGHS has been frequently uplifted, the endothermic gas hydrate dissociation produces a gradual decrease in thermal gradient from the seafloor to the BGHS. Sensitivity analysis for model parameters showed that water depth, amount of uplift, gas hydrate saturation, and basal heat flow strongly influence the gas hydrate dissociation rate and sediment temperature around the BGHS.

  8. NVC-422 inactivates Staphylococcus aureus toxins.

    Science.gov (United States)

    Jekle, Andreas; Yoon, Jungjoo; Zuck, Meghan; Najafi, Ramin; Wang, Lu; Shiau, Timothy; Francavilla, Charles; Rani, Suriani Abdul; Eitzinger, Christian; Nagl, Markus; Anderson, Mark; Debabov, Dmitri

    2013-02-01

    Bacterial pathogens have specific virulence factors (e.g., toxins) that contribute significantly to the virulence and infectivity of microorganisms within the human hosts. Virulence factors are molecules expressed by pathogens that enable colonization, immunoevasion, and immunosuppression, obtaining nutrients from the host or gaining entry into host cells. They can cause pathogenesis by inhibiting or stimulating certain host functions. For example, in systemic Staphylococcus aureus infections, virulence factors such as toxic shock syndrome toxin 1 (TSST-1), staphylococcal enterotoxin A (SEA), and staphylococcal enterotoxin B (SEB) cause sepsis or toxic shock by uncontrolled stimulation of T lymphocytes and by triggering a cytokine storm. In vitro, these superantigens stimulate the proliferation of human peripheral blood mononuclear cells (PBMC) and the release of many cytokines. NVC-422 (N,N-dichloro-2,2-dimethyltaurine) is a broad-spectrum, fast-acting topical anti-infective agent against microbial pathogens, including antibiotic-resistant microbes. Using mass spectrometry, we demonstrate here that NVC-422 oxidizes methionine residues of TSST-1, SEA, SEB, and exfoliative toxin A (ETA). Exposure of virulence factors to 0.1% NVC-422 for 1 h prevented TSST-1-, SEA-, SEB-, and ETA-induced cell proliferation and cytokine release. Moreover, NVC-422 also delayed and reduced the protein A- and clumping factor-associated agglutination of S. aureus cultures. These results show that, in addition to its well-described direct microbicidal activity, NVC-422 can inactivate S. aureus virulence factors through rapid oxidation of methionines.

  9. Photothermal inactivation of bacteria on plasmonic nanostructures

    Science.gov (United States)

    Santos, Greggy M.; Ibañez de Santi Ferrara, Felipe; Zhao, Fusheng; Rodrigues, Debora F.; Shih, Wei-Chuan

    2016-03-01

    Hospital-acquired bacterial infections are frequently associated with the pathogenic biofilms on surfaces of devices and instruments used in medical procedures. The utilization of thermal plasmonic agents is an innovative approach for sterilizing hospital equipment and for in vivo therapeutic treatment of bacterial infection. A photothermal inactivation technique via array of nanoporous gold disks (NPGDs) has been developed by irradiating near infrared (NIR) light onto deposited bacterial cells (Escherichia coli, Bacillus subtilis, Exiguobacterium AT1B) on the surface of metal nanostructure. The physical and photothermal properties of the NPGD substrate were investigated using topographical scanning electron microscopy (SEM) and thermographic infrared imaging. Bacterial viability studies on NPGD substrates irradiated with and without NIR light were evaluated using a fluorescence-based two-component stain assay. The results show that the heat generated from the NPGD substrate promotes high cell death counts (~100%) at short exposure durations (<25 s) even for thermally-resistant bacterial strains. The photothermal effects on NPGD substrate can lead to point-of-care applications.

  10. Cold plasma inactivation of chronic wound bacteria.

    Science.gov (United States)

    Mohd Nasir, N; Lee, B K; Yap, S S; Thong, K L; Yap, S L

    2016-09-01

    Cold plasma is partly ionized non-thermal plasma generated at atmospheric pressure. It has been recognized as an alternative approach in medicine for sterilization of wounds, promotion of wound healing, topical treatment of skin diseases with microbial involvement and treatment of cancer. Cold plasma used in wound therapy inhibits microbes in chronic wound due to its antiseptic effects, while promoting healing by stimulation of cell proliferation and migration of wound relating skin cells. In this study, two types of plasma systems are employed to generate cold plasma: a parallel plate dielectric barrier discharge and a capillary-guided corona discharge. Parameters such as applied voltage, discharge frequency, treatment time and the flow of the carrier gas influence the cold plasma chemistry and therefore change the composition and concentration of plasma species that react with the target sample. Chronic wound that fails to heal often infected by multidrug resistant organisms makes them recalcitrant to healing. Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (Pseudomonas aeruginosa) are two common bacteria in infected and clinically non-infected wounds. The efficacies of the cold plasma generated by the two designs on the inactivation of three different isolates of MRSA and four isolates of P. aeruginosa are reported here.

  11. Meiotic sex chromosome inactivation in Drosophila.

    Science.gov (United States)

    Vibranovski, Maria D

    2014-01-01

    In several different taxa, there is indubitable evidence of transcriptional silencing of the X and Y chromosomes in male meiotic cells of spermatogenesis. However, the so called meiotic sex chromosome inactivation (MSCI) has been recently a hot bed for debate in Drosophila melanogaster. This review covers cytological and genetic observations, data from transgenic constructs with testis-specific promoters, global expression profiles obtained from mutant, wild-type, larvae and adult testes as well as from cells of different stages of spermatogenesis. There is no dispute on that D. melanogaster spermatogenesis presents a down-regulation of X chromosome that does not result from the lack of dosage compensation. However, the issue is currently focused on the level of reduction of X-linked expression, the precise time it occurs and how many genes are affected. The deep examination of data and experiments in this review exposes the limitations intrinsic to the methods of studying MSCI in D. melanogaster. The current methods do not allow us to affirm anything else than the X chromosome down-regulation in meiosis (MSCI). Therefore, conclusion about level, degree or precise timing is inadequate until new approaches are implemented to know the details of MSCI or other processes involved for D. melanogaster model.

  12. Production behaviour of gas hydrate under hot sea water injection : laboratory case study

    Energy Technology Data Exchange (ETDEWEB)

    Nengkoda, A. [Schlumberger, Calgary, AB (Canada); Budhijanto, B.; Supranto, S.; Prasetyo, I.; Purwono, S.; Sutijan, S. [Gadjah Mada Univ., Yogyakarta (Indonesia)

    2010-07-01

    The gas hydrate potential in Indonesia was discussed, with particular reference to offshore production of gas from deep-water gas-hydrates by injection of hot seawater. In 2004, the Indonesian National Agency for Assessment and Application Technology estimated the gas hydrate resource potential to be 850 trillion cubic feet (tcf). To date, the 3 most reliable scenarios for gas hydrate production are thermal stimulation which involves increasing the temperature until the hydrates break into water and gas; depressurization which involves lowering the pressure by pumping out gas at the base of the hydrate to cause dissociation of hydrates into gas; and injection of a chemical inhibitor such as methanol into the hydrated sediments to cause destabilization, thus releasing gas from hydrates. This study investigated the effect of hot seawater injection on the gas hydrate production under laboratory conditions. The temperature profile distribution was examined along with operational parameters and flow characteristics of the dissociated gas and water from hydrates in porous systems under a synthetic hydrate setup. The study showed that gas production increases with time until a maximum is reached, at which time it begins to decrease. The energy ratio of thermal stimulation production was found to be influenced by the injection water temperature and rate as well as the hydrate content in the synthetic sediment. Scale problems were found to be associated with high temperature seawater injection. 8 refs., 3 tabs., 7 figs.

  13. Evaluation of Gas Hydrate at Alaminos Canyon 810, Northern Gulf of Mexico Slope

    Science.gov (United States)

    Yang, C.; Cook, A.; Sawyer, D.; Hillman, J. I. T.

    2016-12-01

    We characterize the gas hydrate reservoir in Alaminos Canyon Block 810 (AC810) on the northern Gulf of Mexico slope, approximately 400 km southeast of Houston, Texas, USA. Three-dimensional seismic data shows a bottom-simulating-reflection (BSR), over 30 km2, which suggests that a significant gas hydrate accumulation may occur at AC810. Furthermore, logging while drilling (LWD) data acquired from a Statoil well located that penetrated the BSR near the crest of the regional anticline indicates two possible gas hydrate units (Hydrate Unit A and Hydrate Unit B). LWD data in this interval are limited to gamma ray and resistivity only. Resistivity curve separations are observed in Hydrate Unit A (131 to 253 mbsf) suggesting hydrate-filled fractures in marine mud. A spiky high resistivity response in Hydrate Unit B (308 to 354 mbsf) could either be a marine mud or a sand-prone interval. The abrupt decrease (from 7 to 1 Ωm) in resistivity logs at 357 mbsf generally corresponds with the interpreted base of hydrate stability, as the BSR is observed near 350 mbsf on the seismic data. To further investigate the formation characteristics, we generate synthetic traces using general velocity and density trends for marine sediments to match the seismic trace extracted at the Statoil well. We consider models with 1) free gas and 2) water only below the base of hydrate stability. In our free gas-below models, we find the velocity of Hydrate Unit A and Hydrate Unit B is generally low and does not deviate significantly from the general velocity trends, suggesting that gas hydrate is present in a marine mud. In the water-below model, the compressional velocity of Hydrate Unit B ranges from 2450 m/s to 3150 m/s. This velocity is similar to the velocity of high hydrate saturation in sand; typically greater than 2500 m/s. This may indicate that Hydrate Unit B is sand with high hydrate saturation; however, to achieve a suitable match between the water-below synthetic seismogram and the

  14. Synthesis and Antimutagenic Effects of SelenaMorpholine Hydrate

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The synthesis of selenamorpholine hydrate was described and its antimutagenic effects were investigated by the Ames tests. The results indicated that the mutation induced by the indirect mutagen 2-AF was inhibited obviously by selenamorpholine hydrate at the dosage of Se 0. 16~100 μg /dish for 35.8%~53.7%(TA97) and the mutation induced by direct mutagen Dexon was inhibited for 6.2%~30.0%(TA97) and 2.3%~34.1%(TA100). The mutagenesis of the indirect mutagen cyclophosphamide was suppressed for 5.4%~16.1% by selenamorpholine hydrate at the dosage of Se 0. 16~100 μg /dish.

  15. Hydration swelling characteristics of needle-punched geosynthetic clay liners

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A series of confined swell tests were conducted on a needle-punched geosynthetic clay liner (GCL)with tap water as the hydration medium. The effects of the static confining stress on the swelling characteristics of GCLs and the hydration time under different confining stresses were explored. Increasing the static confining stress led to: shorter hydration time; smaller final GCL height; less final GCL bulk void ratio; smaller final bentonite moisture content. The confined swell pressure determined for the tested GCL was 82.2 kPa, and the relationships between confining stress, final bulk void ratio (or final GCL height, final bentonite moisture content) were attained through the analyses of the confined swell test results in this study.

  16. Temperature dependence of protein hydration hydrodynamics by molecular dynamics simulations.

    Energy Technology Data Exchange (ETDEWEB)

    Lau, E Y; Krishnan, V V

    2007-07-18

    The dynamics of water molecules near the protein surface are different from those of bulk water and influence the structure and dynamics of the protein itself. To elucidate the temperature dependence hydration dynamics of water molecules, we present results from the molecular dynamic simulation of the water molecules surrounding two proteins (Carboxypeptidase inhibitor and Ovomucoid) at seven different temperatures (T=273 to 303 K, in increments of 5 K). Translational diffusion coefficients of the surface water and bulk water molecules were estimated from 2 ns molecular dynamics simulation trajectories. Temperature dependence of the estimated bulk water diffusion closely reflects the experimental values, while hydration water diffusion is retarded significantly due to the protein. Protein surface induced scaling of translational dynamics of the hydration waters is uniform over the temperature range studied, suggesting the importance protein-water interactions.

  17. Silica surfaces lubrication by hydrated cations adsorption from electrolyte solutions.

    Science.gov (United States)

    Donose, Bogdan C; Vakarelski, Ivan U; Higashitani, Ko

    2005-03-01

    Adsorption of hydrated cations on hydrophilic surfaces has been related to a variety of phenomena associated with the short-range interaction forces and mechanisms of the adhesive contact between the surfaces. Here we have investigated the effect of the adsorption of cations on the lateral interaction. Using lateral force microscopy (LFM), we have measured the friction force between a silica particle and silica wafer in pure water and in electrolyte solutions of LiCl, NaCl, and CsCl salts. A significant lubrication effect was demonstrated for solutions of high electrolyte concentrations. It was found that the adsorbed layers of smaller and more hydrated cations have a higher lubrication capacity than the layers of larger and less hydrated cations. Additionally, we have demonstrated a characteristic dependence of the friction force on the sliding velocity of surfaces. A mechanism for the observed phenomena based on the microstructures of the adsorbed layers is proposed.

  18. Natural gas hydrates and the mystery of the Bermuda Triangle

    Energy Technology Data Exchange (ETDEWEB)

    Gruy, H.J.

    1998-03-01

    Natural gas hydrates occur on the ocean floor in such great volumes that they contain twice as much carbon as all known coal, oil and conventional natural gas deposits. Releases of this gas caused by sediment slides and other natural causes have resulted in huge slugs of gas saturated water with density too low to float a ship, and enough localized atmospheric contamination to choke air aspirated aircraft engines. The unexplained disappearances of ships and aircraft along with their crews and passengers in the Bermuda Triangle may be tied to the natural venting of gas hydrates. The paper describes what gas hydrates are, their formation and release, and their possible link to the mystery of the Bermuda Triangle.

  19. Investigating the Hydration of CM2 meteorites by IR spectroscopy

    CERN Document Server

    Góbi, S; Beck, P; Quirico, E; Schmidt, B

    2014-01-01

    Chondritic meteorites are of great interest since they are one of the most ancient remnants of the early solar system. Some of them, like the carbonaceous CM meteorites experienced aqueous alteration thus their olivine content transformed more or less into hydrated silicates such as phyllosilicates. These hydrated CM2 meteorites have been investigated in KBr pellets by means of Fourier transform infrared (FT-IR) spectroscopy. In our focus of interest was to study the 3 and 10 $\\mu$m (3000 and 1000 cm$^{-1}$, the O$-$H and silicate streching) bands of several CM2 chondrites. By investigating these signals the water content and the extent of hydration can be determined. In order to achieve this, development of a new pellet production method was essential. This technique facilitates the elimination of adsorbed water coming from the surrounding environment, which would complicate correct interpretation of the results.

  20. Determination of Nucleic Acid Hydration Using Osmotic Stress

    Science.gov (United States)

    Rozners, Eriks

    2010-01-01

    Understanding the role water plays in biological processes requires detailed knowledge of the phenomena of biopolymer hydration. Crystal structures have identified exact sites occupied by the water molecules in immediate hydration layers. NMR and molecular modeling have provided information on dynamics of water molecules occupying these sites. However, these studies give little information on the thermodynamic contribution of water molecules to conformational equilibria and recognition affinity. This unit describes probing of nucleic acid hydration using osmotic stress, a method that provides thermodynamic information complementary to crystallography, NMR and molecular modeling. Osmotic stress monitors the depression of melting temperature upon decreasing the water activity and calculates the number of thermodynamically unique water molecules associated with the double helix and released from the single strands upon melting. PMID:21154532

  1. Structure and Hydration of Highly Branched, Monodisperse Phytoglycogen Nanoparticles

    Science.gov (United States)

    Atkinson, John; Nickels, Jonathan; Stanley, Christopher; Diallo, Souleymane; Katsaras, John; Dutcher, John

    Monodisperse phytoglycogen nanoparticles are a promising, new soft colloidal nanomaterial with many applications in the personal care, food, nutraceutical and pharmaceutical industries. These applications rely on exceptional properties that emerge from the highly branched structure of phytoglycogen and its interaction with water, such as extraordinarily high water retention, and low viscosity and exceptional stability in water. The structure and hydration of the nanoparticles was characterized using small angle neutron scattering (SANS) and quasielastic neutron scattering (QENS). SANS allowed us to determine the size of the nanoparticles, evaluate their radial density profile, quantify the particle-to-particle spacing, and determine their water content. The results show clearly that the nanoparticles are highly hydrated, with each nanoparticle containing 250% of its mass in water, and that aqueous dispersions approach a jamming transition at ~ 25% (w/w). QENS experiments provided an independent and consistent measure of the high level of hydration of the particles.

  2. Formation of natural gas hydrates in marine sediments. Gas hydrate growth and stability conditioned by host sediment properties

    Science.gov (United States)

    Clennell, M.B.; Henry, P.; Hovland, M.; Booth, J.S.; Winters, W.J.; Thomas, M.

    2000-01-01

    The stability conditions of submarine gas hydrates (methane clathrates) are largely dictated by pressure, temperature, gas composition, and pore water salinity. However, the physical properties and surface chemistry of the host sediments also affect the thermodynamic state, growth kinetics, spatial distributions, and growth forms of clathrates. Our model presumes that gas hydrate behaves in a way analogous to ice in the pores of a freezing soil, where capillary forces influence the energy balance. Hydrate growth is inhibited within fine-grained sediments because of the excess internal phase pressure of small crystals with high surface curvature that coexist with liquid water in small pores. Therefore, the base of gas hydrate stability in a sequence of fine sediments is predicted by our model to occur at a lower temperature, and so nearer to the seabed than would be calculated from bulk thermodynamic equilibrium. The growth forms commonly observed in hydrate samples recovered from marine sediments (nodules, sheets, and lenses in muds; cements in sand and ash layers) can be explained by a requirement to minimize the excess of mechanical and surface energy in the system.

  3. Monte Carlo simulations of a protein molecule with and without hydration energy calculated by the hydration-shell model.

    Science.gov (United States)

    Wako, H

    1989-12-01

    Monte Carlo simulations of a small protein, crambin, were carried out with and without hydration energy. The methodology presented here is characterized, as compared with the other similar simulations of proteins in solution, by two points: (1) protein conformations are treated in fixed geometry so that dihedral angles are independent variables rather than cartesian coordinates of atoms; and (2) instead of treating water molecules explicitly in the calculation, hydration energy is incorporated in the conformational energy function in the form of sigma giAi, where Ai is the accessible surface area of an atomic group i in a given conformation, and gi is the free energy of hydration per unit surface area of the atomic group (i.e., hydration-shell model). Reality of this model was tested by carrying out Monte Carlo simulations for the two kinds of starting conformations, native and unfolded ones, and in the two kinds of systems, in vacuo and solution. In the simulations starting from the native conformation, the differences between the mean properties in vacuo and solution simulations are not very large, but their fluctuations around the mean conformation during the simulation are relatively smaller in solution than in vacuo. On the other hand, in the simulations starting from the unfolded conformation, the molecule fluctuates much more largely in solution than in vacuo, and the effects of taking into account the hydration energy are pronounced very much. The results suggest that the method presented in this paper is useful for the simulations of proteins in solution.

  4. Dynamic morphology of gas hydrate on a methane bubble in water: Observations and new insights for hydrate film models

    Science.gov (United States)

    Warzinski, Robert P.; Lynn, Ronald; Haljasmaa, Igor; Leifer, Ira; Shaffer, Frank; Anderson, Brian J.; Levine, Jonathan S.

    2014-10-01

    Predicting the fate of subsea hydrocarbon gases escaping into seawater is complicated by potential formation of hydrate on rising bubbles that can enhance their survival in the water column, allowing gas to reach shallower depths and the atmosphere. The precise nature and influence of hydrate coatings on bubble hydrodynamics and dissolution is largely unknown. Here we present high-definition, experimental observations of complex surficial mechanisms governing methane bubble hydrate formation and dissociation during transit of a simulated oceanic water column that reveal a temporal progression of deep-sea controlling mechanisms. Synergistic feedbacks between bubble hydrodynamics, hydrate morphology, and coverage characteristics were discovered. Morphological changes on the bubble surface appear analogous to macroscale, sea ice processes, presenting new mechanistic insights. An inverse linear relationship between hydrate coverage and bubble dissolution rate is indicated. Understanding and incorporating these phenomena into bubble and bubble plume models will be necessary to accurately predict global greenhouse gas budgets for warming ocean scenarios and hydrocarbon transport from anthropogenic or natural deep-sea eruptions.

  5. The strength and rheology of methane clathrate hydrate

    Science.gov (United States)

    Durham, W.B.; Kirby, S.H.; Stern, L.A.; Zhang, W.

    2003-01-01

    Methane clathrate hydrate (structure I) is found to be very strong, based on laboratory triaxial deformation experiments we have carried out on samples of synthetic, high-purity, polycrystalline material. Samples were deformed in compressional creep tests (i.e., constant applied stress, ??), at conditions of confining pressure P = 50 and 100 MPa, strain rate 4.5 ?? 10-8 ??? ?? ??? 4.3 ?? 10-4 s-1, temperature 260 ??? T ??? 287 K, and internal methane pressure 10 ??? PCH4 ??? 15 MPa. At steady state, typically reached in a few percent strain, methane hydrate exhibited strength that was far higher than expected on the basis of published work. In terms of the standard high-temperature creep law, ?? = A??ne-(E*+PV*)/RT the rheology is described by the constants A = 108.55 MPa-n s-1, n = 2.2, E* = 90,000 J mol-1, and V* = 19 cm3 mol-1. For comparison at temperatures just below the ice point, methane hydrate at a given strain rate is over 20 times stronger than ice, and the contrast increases at lower temperatures. The possible occurrence of syntectonic dissociation of methane hydrate to methane plus free water in these experiments suggests that the high strength measured here may be only a lower bound. On Earth, high strength in hydrate-bearing formations implies higher energy release upon decomposition and subsequent failure. In the outer solar system, if Titan has a 100-km-thick near-surface layer of high-strength, low-thermal conductivity methane hydrate as has been suggested, its interior is likely to be considerably warmer than previously expected.

  6. Ocean Observatory Gas Hydrates Experiments on the Cascadia Margin

    Science.gov (United States)

    Scherwath, Martin; Heesemann, Martin; Mihaly, Steve; Kelley, Deborah; Moran, Kate; Philip, Brendan; Römer, Miriam; Riedel, Michael; Solomon, Evan; Thomsen, Laurenz; Purser, Autun

    2016-04-01

    Ocean Networks Canada's (ONC's) NEPTUNE observatory and the Ocean Observatories Initiative's (OOI's) Cabled Array installations enable long-term gas hydrate experiments on the Cascadia Margin offshore Vancouver Island and Washington and Oregon State. The great advantage of cabled ocean networks in providing power and high bandwidth internet access to the seafloor on a permanent basis is allowing constant monitoring and interacting with experiments hundreds of kilometres away from shore throughout the year. Many different gas hydrate related experiments are installed at three various hydrate nodes, Clayoquot Slope and Barkley Canyon offshore Vancouver Island and Southern Hydrate Ridge offshore Oregon. As an example, a seafloor crawler called Wally is operated from Bremen in Germany by Jacobs University, carrying out measurements by moving around the Barkley hydrate mounds on a daily basis, determining for instance the speed of dynamic changes of the benthic communities. In another example, several years of hourly sonar data show gas bubbles rising from the seafloor near the Bullseye Vent with varying intensities, allowing statistically sound correlations with other seafloor parameters such as ground shaking, temperature and pressure variations and currents, where tidal pressure appearing as the main driver. The Southern Hydrate Ridge is now equipped with the world's first long-term seafloor mass spectrometer, co-located with a camera and lights, hydrophone, current meters, pressure sensor, autonomous OSMO and fluid samplers, and is surrounded by a seismometer array for local seismicity. The data are freely available through open access data portals at: http://dmas.uvic.ca/home and https://ooinet.oceanobservatories.org/

  7. Seismic velocities for hydrate-bearing sediments using weighted equation

    Science.gov (United States)

    Lee, M.W.; Hutchinson, D.R.; Collett, T.S.; Dillon, William P.

    1996-01-01

    A weighted equation based on the three-phase time-average and Wood equations is applied to derive a relationship between the compressional wave (P wave) velocity and the amount of hydrates filling the pore space. The proposed theory predicts accurate P wave velocities of marine sediments in the porosity range of 40-80% and provides a practical means of estimating the amount of in situ hydrate using seismic velocity. The shear (S) wave velocity is derived under the assumption that the P to S wave velocity ratio of the hydrated sediments is proportional to the weighted average of the P to S wave velocity ratios of the constituent components of the sediment. In the case that all constituent components are known, a weighted equation using multiphase time-average and Wood equations is possible. However, this study showed that a three-phase equation with modified matrix velocity, compensated for the clay content, is sufficient to accurately predict the compressional wave velocities for the marine sediments. This theory was applied to the laboratory measurements of the P and S wave velocities in permafrost samples to infer the amount of ice in the unconsolidated sediment. The results are comparable to the results obtained by repeatedly applying the two-phase wave scattering theory. The theory predicts that the Poisson's ratio of the hydrated sediments decreases as the hydrate concentration increases and the porosity decreases. In consequence, the amplitude versus offset (AVO) data for the bottom-simulating reflections may reveal positive, negative, or no AVO anomalies depending on the concentration of hydrates in the sediments.

  8. Hydrated mineral stratigraphy of Ius Chasma, Valles Marineris

    Science.gov (United States)

    Roach, L.H.; Mustard, J.F.; Swayze, G.; Milliken, R.E.; Bishop, J.L.; Murchie, S.L.; Lichtenberg, K.

    2010-01-01

    New high-resolution spectral and morphologic imaging of deposits on walls and floor of Ius Chasma extend previous geomorphic mapping, and permit a new interpretation of aqueous processes that occurred during the development of Valles Marineris. We identify hydrated mineralogy based on visible-near infrared (VNIR) absorptions. We map the extents of these units with CRISM spectral data as well as morphologies in CTX and HiRISE imagery. Three cross-sections across Ius Chasma illustrate the interpreted mineral stratigraphy. Multiple episodes formed and transported hydrated minerals within Ius Chasma. Polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma. They may have been precipitates in a closed basin or diagenetically altered after deposition. Fluvial or aeolian processes then deposited layered Fe/Mg smectite and hydrated silicate on the chasma floor, postdating the sulfates. The smectite apparently was weathered out of Noachian-age wallrock and transported to the depositional sites. The overlying hydrated silicate is interpreted to be an acid-leached phyllosilicate transformed from the underlying smectite unit, or a smectite/jarosite mixture. The finely layered smectite and massive hydrated silicate units have an erosional unconformity between them, that marks a change in surface water chemistry. Landslides transported large blocks of wallrock, some altered to contain Fe/Mg smectite, to the chasma floor. After the last episode of normal faulting and subsequent landslides, opal was transported short distances into the chasma from a few m-thick light-toned layer near the top of the wallrock, by sapping channels in Louros Valles. Alternatively, the material was transported into the chasma and then altered to opal. The superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential, distinct aqueous environments, characterized by alkaline

  9. Water diffusion in fully hydrated porcine stratum corneum

    Energy Technology Data Exchange (ETDEWEB)

    Pieper, J.; Charalambopoulou, G.; Steriotis, Th.; Vasenkov, S.; Desmedt, A.; Lechner, R.E

    2003-08-01

    The microscopic mechanisms of water diffusion in fully hydrated porcine stratum corneum (SC) have been studied by a combination of incoherent quasielastic neutron scattering (QENS) and pulsed field gradient-nuclear magnetic resonance (PFG-NMR) for two sample orientations. The presence of three types of water in fully hydrated SC is inferred on the basis of water sorption isotherm data, i.e., (a) bound and (b) weakly bound hydration water forming layers between adjacent lipid bilayers of SC, as well as (c) bulk water probably located in the corneocytes and in intercellular regions. Water self-diffusion coefficients for motions parallel and perpendicular to the membrane plane of D{sub parallel}=3.30x10{sup -10} m{sup 2}/s and D{sub perpendicular}=1.56x10{sup -10} m{sup 2}/s, respectively, were determined by PFG-NMR and assigned to the translational diffusion of weakly bound water. QENS measurements have been carried out using different samples hydrated with H{sub 2}O and D{sub 2}O, respectively, in order to separate the contribution of SC from that of the water. The QENS data for both sample orientations and two different energy resolutions can be fitted by a model which accounts for the microscopic dynamics of all three aforementioned types of water. This analysis establishes rotational diffusion coefficients for bound and weakly bound hydration water of 0.025 and 0.030 meV, respectively. Furthermore, the QENS data prove the presence of bulk water in fully hydrated SC samples.

  10. CHLORINE INACTIVATION OF CATEGORY "A" BIO-TERRORISM AGENTS

    Science.gov (United States)

    This poster presents information on the inactivation of select bioterrorist agents. Information will be presented on chlorine disinfection of vegetative cells of Brucella suis, Brucella melitensis, Burkholderia mallei, Burkholderia pseudomallei, Francisella tularensis and endos...

  11. CHLORINE INACTIVATION OF CATEGORY "A" BIO-TERRORISM AGENTS

    Science.gov (United States)

    This poster presents information on the inactivation of select bioterrorist agents. Information will be presented on chlorine disinfection of vegetative cells of Brucella suis, Brucella melitensis, Burkholderia mallei, Burkholderia pseudomallei, Francisella tularensis and endos...

  12. Application of electrolysis to inactivation of antibacterials in clinical use.

    Science.gov (United States)

    Nakano, Takashi; Hirose, Jun; Kobayashi, Toyohide; Hiro, Naoki; Kondo, Fumitake; Tamai, Hiroshi; Tanaka, Kazuhiko; Sano, Kouichi

    2013-04-01

    Contamination of surface water by antibacterial pharmaceuticals (antibacterials) from clinical settings may affect aquatic organisms, plants growth, and environmental floral bacteria. One of the methods to decrease the contamination is inactivation of antibacterials before being discharged to the sewage system. Recently, we reported the novel method based on electrolysis for detoxifying wastewater containing antineoplastics. In the present study, to clarify whether the electrolysis method is applicable to the inactivation of antibacterials, we electrolyzed solutions of 10 groups of individual antibacterials including amikacin sulfate (AMK) and a mixture (MIX) of some commercial antibacterials commonly prescribed at hospitals, and measured their antibacterial activities. AMK was inactivated in its antibacterial activities and its concentration decreased by electrolysis in a time-dependent manner. Eighty to ninety-nine percent of almost all antibacterials and MIX were inactivated within 6h of electrolysis. Additionally, cytotoxicity was not detected in any of the electrolyzed solutions of antibacterials and MIX by the Molt-4-based cytotoxicity test.

  13. Conjugated Polymers/DNA Hybrid Materials for Protein Inactivation.

    Science.gov (United States)

    Zhao, Likun; Zhang, Jiangyan; Xu, Huiming; Geng, Hao; Cheng, Yongqiang

    2016-09-01

    Chromophore-assisted light inactivation (CALI) is a powerful tool for analyzing protein functions due to the high degree of spatial and temporal resolution. In this work, we demonstrate a CALI approach based on conjugated polymers (CPs)/DNA hybrid material for protein inactivation. The target protein is conjugated with single-stranded DNA in advance. Single-stranded DNA can form CPs/DNA hybrid material with cationic CPs via electrostatic and hydrophobic interactions. Through the formation of CPs/DNA hybrid material, the target protein that is conjugated with DNA is brought into close proximity to CPs. Under irradiation, CPs harvest light and generate reactive oxygen species (ROS), resulting in the inactivation of the adjacent target protein. This approach can efficiently inactivate any target protein which is conjugated with DNA and has good specificity and universality, providing a new strategy for studies of protein function and adjustment of protein activity.

  14. Inactivation of protozoan parasites in food, water, and environmental systems.

    Science.gov (United States)

    Erickson, Marilyn C; Ortega, Ynes R

    2006-11-01

    Protozoan parasites can survive under ambient and refrigerated storage conditions when associated with a range of substrates. Consequently, various treatments have been used to inactivate protozoan parasites (Giardia, Cryptosporidium, and Cyclospora) in food, water, and environmental systems. Physical treatments that affect survival or removal of protozoan parasites include freezing, heating, filtration, sedimentation, UV light, irradiation, high pressure, and ultrasound. Ozone is a more effective chemical disinfectant than chlorine or chlorine dioxide for inactivation of protozoan parasites in water systems. However, sequential inactivation treatments can optimize existing treatments through synergistic effects. Careful selection of methods to evaluate inactivation treatments is needed because many studies that have employed vital dye stains and in vitro excystation have produced underestimations of the effectiveness of these treatments.

  15. Biocontrol interventions for inactivation of foodborne pathogens on produce

    Science.gov (United States)

    Post-harvest interventions for control of foodborne pathogens on minimally processed foods are crucial for food safety. Biocontrol interventions have the primary objective of developing novel antagonists in combinations with physical and chemical interventions to inactivate pathogenic microbes. Ther...

  16. Pulsed ultra-violet inactivation spectrum of Escherichia coli.

    Science.gov (United States)

    Wang, T; Macgregor, S J; Anderson, J G; Woolsey, G A

    2005-08-01

    Inactivation of Escherichia coli is examined using ultra-violet (UV) radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to the infrared region with a rich UV content. The flashlamp provides high-energy UV output using a small number of short-duration pulses (30 micros). The flashlamp is used with a monochromator to investigate the wavelength sensitivity of E. coli to inactivation by the pulsed UV light. Using 8 nm wide pulses of UV radiation, the most efficient inactivation is found to occur at around 270 nm and no inactivation is observed above 300 nm. A pyroelectric detector allows the energy dose to be determined at each wavelength, and a peak value for E. coli population reduction of 0.43 log per mJ/cm(2) is measured at 270 nm. The results are compared with the published data available for continuous UV light sources.

  17. Pulsed UV‐light inactivation of poliovirus and adenovirus

    National Research Council Canada - National Science Library

    Lamont, Y; Rzeżutka, A; Anderson, J.G; MacGregor, S.J; Given, M.J; Deppe, C; Cook, N

    2007-01-01

    .... Significance and Impact of the Study:  Pulsed UV‐light treatment proved successful in the inactivation of poliovirus and adenovirus, and represents an alternative to continuous‐wave UV treatment.

  18. Hofmeister effects: interplay of hydration, nonelectrostatic potentials, and ion size.

    Science.gov (United States)

    Parsons, Drew F; Boström, Mathias; Lo Nostro, Pierandrea; Ninham, Barry W

    2011-07-21

    The classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloids, and corresponding theories of electrolytes, are unable to explain ion specific forces between colloidal particles quantitatively. The same is true generally, for surfactant aggregates, lipids, proteins, for zeta and membrane potentials and in adsorption phenomena. Even with fitting parameters the theory is not predictive. The classical theories of interactions begin with continuum solvent electrostatic (double layer) forces. Extensions to include surface hydration are taken care of with concepts like inner and outer Helmholtz planes, and "dressed" ion sizes. The opposing quantum mechanical attractive forces (variously termed van der Waals, Hamaker, Lifshitz, dispersion, nonelectrostatic forces) are treated separately from electrostatic forces. The ansatz that separates electrostatic and quantum forces can be shown to be thermodynamically inconsistent. Hofmeister or specific ion effects usually show up above ≈10(-2) molar salt. Parameters to accommodate these in terms of hydration and ion size had to be invoked, specific to each case. Ionic dispersion forces, between ions and solvent, for ion-ion and ion-surface interactions are not explicit in classical theories that use "effective" potentials. It can be shown that the missing ionic quantum fluctuation forces have a large role to play in specific ion effects, and in hydration. In a consistent predictive theory they have to be included at the same level as the nonlinear electrostatic forces that form the skeletal framework of standard theory. This poses a challenge. The challenges go further than academic theory and have implications for the interpretation and meaning of concepts like pH, buffers and membrane potentials, and for their experimental interpretation. In this article we overview recent quantitative developments in our evolving understanding of the theoretical origins of specific ion, or Hofmeister effects. These are demonstrated

  19. Gas Phase Hydration of Methyl Glyoxal to Form the Gemdiol

    Science.gov (United States)

    Kroll, Jay A.; Axson, Jessica L.; Vaida, Veronica

    2016-06-01

    Methylglyoxal is a known oxidation product of volatile organic compounds (VOCs) in Earth's atmosphere. While the gas phase chemistry of methylglyoxal is fairly well understood, its modeled concentration and role in the formation of secondary organic aerosol (SOA) continues to be controversial. The gas phase hydration of methylglyoxal to form a gemdiol has not been widely considered for water-restricted environments such as the atmosphere. However, this process may have important consequences for the atmospheric processing of VOCs. We will report on spectroscopic work done in the Vaida laboratory studying the hydration of methylglyoxal and discuss the implications for understanding the atmospheric processing and fate of methylglyoxal and similar molecules.

  20. Characterization of gas hydrates provinces off Norway-Svalbard

    Energy Technology Data Exchange (ETDEWEB)

    Vanneste, M.; Kvalstad, T.J.; Forsberg, C.F.; Pfaffhuber, A. [NGI, Oslo (Norway); ICG, Oslo (Norway); Bunz, S.; Mienert, J. [Tromso Univ., Tromso (Norway)

    2010-07-01

    The characterization of gas hydrates provinces off Norway-Svalbard were discussed in this presentation. Relevant research and development projects and activities were listed. Bottom simulating reflectors as a key seismic proxy were discussed. Seismic techniques such as p-waves and s-waves were identified. The quantification and saturation from velocity anomalies were illustrated along with the gas hydrate reservoir potential off Norway-Svalbard. Some interesting cases were presented, including the Nankai; Lake Baikal in Siberia; and the Black Sea. The presentation concluded with a discussion of lessons learned. The presentation noted that mapping and quantification requires integration of methods and techniques. figs.

  1. EFFECT OF DIFFERENT OPERATION METHODS ON METHANE HYDRATE FORMATION

    Institute of Scientific and Technical Information of China (English)

    HAO Wenfeng; FAN Shuanshi; WANG Jinqu

    2003-01-01

    Three experiments of static state storage method, low-temperature and constant-pressure storage method and low-temperature and constant-pressure storage method were carried out to investigate which method was best in gas hydrate. The relationships of hydrate rate, capacity and liquid temperature versus time were derived and three results were contrasted. The experimental results show lowtemperature and constant-pressure method is better than the other two methods because it's operation period is shorter and storage capacity is larger than the other two. Low-temperature and constant-pressure method is the best method. So new method will be new research objective.

  2. Compositional characteristics and hydration behavior of mineral trioxide aggregates

    Directory of Open Access Journals (Sweden)

    Wen-Hsi Wang

    2010-06-01

    Full Text Available Mineral trioxide aggregate (MTA was one of most popular biomaterials for endodontic treatment in the past decade. Its superb biocompatibility, sealing ability and surface for tissue adhesion all make MTA a potential candidate for many dental applications, such as apexification, perforation repair, repair of root resorption, and as a root-end filling material. There are many review articles regarding the physical, chemical and biological properties of MTA. However, there are few reviews discussing the relationship between the composition and hydration behavior of MTA. The aim of this article was to provide a systematic review regarding the compositional characteristics and hydration behavior of MTA.

  3. Two-dimensional protonic percolation on lightly hydrated purple membrane

    OpenAIRE

    Rupley, John A.; Siemankowski, Linda; Careri, Giorgio; Bruni, Fabio

    1988-01-01

    The capacitance and dielectric loss factor were measured for a sample of purple membrane of Halobacterium halobium as a function of hydration level (0.017 to >0.2 g of water/g of membrane) and frequency (10 kHz to 10 MHz). The capacitance and the derived conductivity show explosive growth above a threshold hydration level, hc ≈ 0.0456. The conductivity shows a deuterium isotope effect, H/2H = 1.38, in close agreement with expectation for a protonic process. The level hc is frequency independe...

  4. Frozen heat: Global outlook on methane gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Beaudoin, Yannick; Solgaard, Anne

    2010-09-15

    The United Nations Environment Programme via its collaborating center in Norway, UNEP/GRID-Arendal, is undertaking an assessment of the state of the knowledge of methane gas hydrates. The Global Outlook on Methane Gas Hydrates seeks to bridge the gap between the science, research and development activities related to this potential large scale unconventional source of natural gas and the needs of decision makers and the general public to understand the underlying societal and environmental drivers and impacts. The Outlook aims to provide credible and unbiased information sourced from stakeholders representing the environment, government, industry and society.

  5. Inactivation of Ascaris suum by Short-Chain Fatty Acids▿

    OpenAIRE

    Butkus, Michael A.; Hughes, Kelly T.; Bowman, Dwight D; Liotta, Janice L.; Jenkins, Michael B.; Labare, Michael P.

    2010-01-01

    Ascaris suum eggs were inactivated in distilled water and digested sludge by butanoic, pentanoic, and hexanoic acids. The fatty acids (short-chain fatty acids [SCFA]) were effective only when protonated and at sufficient concentrations. The conjugate bases were not effective at the concentrations evaluated. Predictions from an inhibition model (50% inhibitory concentration [IC50]) based on quantitative structure-activity relationships were congruent with inactivation data.

  6. 21 CFR 610.11a - Inactivated influenza vaccine, general safety test.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Inactivated influenza vaccine, general safety test... Inactivated influenza vaccine, general safety test. For inactivated influenza vaccine, the general safety test... pig. The requirements for general safety for inactivated influenza vaccine shall not be considered...

  7. Mineralogical Study of Hydrated IDPs: X-Ray Diffraction and Transmission Electron Microscopy

    Science.gov (United States)

    Nakamura, K.; Keller, L. P.; Nakamura, T.; Noguchi, T.; Zolensky, M. E.

    2004-01-01

    Chondritic hydrated interplanetary dust particles (IDPs) comprise up to 50% of all IDPs collected in the stratosphere [1]. Hydrated IDPs are generally believed to be derived from asteroidal sources that have undergone aqueous alteration. However, the high C contents of hydrated IDPs (by 2 to 6X CI levels [2,3]) indicate that they are probably not derived from the same parent bodies sampled by the known chondritic meteorites. Some hydrated IDPs exhibit large deuterium enrichments [4] similar to those observed in anhydrous IDPs. Both anhydrous and hydrated IDPs contain a variety of anhydrous minerals such as silicates, sulfides, oxides, and carbonates. Controversies on hydrated IDPs still exist regarding their formation, history, and relationship to other primitive solar system materials, because of the lack of a systematic series of analysis on individual hydrated IDPs. In this study, we combine our observations of the bulk mineralogy, mineral/ organic chemistry in order to derive a more complete picture of hydrated IDPs.

  8. Artificial hydration at the end of life in an oncology ward in Singapore

    Directory of Open Access Journals (Sweden)

    Lalit Kumar Radha Krishna

    2010-01-01

    Conclusion: Artificial hydration during the last 48 h of life did not have any significant impact on symptoms related to hydration status, medication use or on survival in terminally ill cancer patients under palliative care.

  9. Submarine methane hydrates - Potential fuel resource of the 21st century

    Digital Repository Service at National Institute of Oceanography (India)

    Desa, E.

    initiated to date, some interesting ideas have been conceived for the production of methane from hydrates and its transportation to shore. Apart from being an abundant fuel resource, methane hydrates are also a matter of concern, as destabilization of sub...

  10. Transient seafloor venting on continental slopes from warming-induced methane hydrate dissociation

    Science.gov (United States)

    Darnell, K. N.; Flemings, P. B.

    2015-12-01

    Methane held in frozen hydrate cages within marine sediment comprises one of the largest carbon reservoirs on the planet. Recent submarine observations of widespread methane seepage may record hydrate dissociation due to oceanic warming, which consequently may further amplify climate change. Here we simulate the effect of seafloor warming on marine hydrate deposits using a multiphase flow model. We show that hydrate dissociation, gas migration, and subsequent hydrate formation cangenerate temporary methane venting into the ocean through the hydrate stability zone. Methane seeps venting through the hydrate stability zone on the eastern Atlantic margin may record this process due to warming begun thousands of years ago. Our results contrast with the traditional view that venting occurs only updip of the hydrate stability zone.

  11. Effect of temperature fluctuation on hydrate-based CO2 separation from fuel gas

    Institute of Scientific and Technical Information of China (English)

    Xiaosen Li; Chungang Xu; Zhaoyang Chen; Huijie Wu; Jing Cai

    2011-01-01

    A new method of temperature fluctuation is proposed to promote the process of hydrate-based CO2 separation from fuel gas in this work according to the dual nature of CO2 solubility in hydrate forming and non-hydrate forming regions [1].The temperature fluctuation operated in the process of hydrate formation improves the formation of gas hydrate observably.The amount of the gas consumed with temperature fluctuation is approximately 35% more than that without temperature fluctuation.It is found that only the temperature fluctuation operated in the period of forming hydrate leads to a good effect on CO2 separation.Meanwhile,with the proceeding of hydrate formation,the effect of temperature fluctuation on the gas hydrate gradually reduces,and little effect is left in the completion term.The CO2 separation efficiencies in the separation processes with the effective temperature fluctuations are improved remarkably.

  12. Reservoir controls on the occurrence and production of gas hydrates in nature

    Science.gov (United States)

    Collett, Timothy Scott

    2014-01-01

    Gas hydrates in both arctic permafrost regions and deep marine settings can occur at high concentrations in sand-dominated reservoirs, which have been the focus of gas hydrate exploration and production studies in

  13. Water permeability in hydrate-bearing sediments: A pore-scale study

    Science.gov (United States)

    Dai, Sheng; Seol, Yongkoo

    2014-06-01

    Permeability is a critical parameter governing methane flux and fluid flow in hydrate-bearing sediments; however, limited valid data are available due to experimental challenges. Here we investigate the relationship between apparent water permeability (k') and hydrate saturation (Sh), accounting for hydrate pore-scale growth habit and meso-scale heterogeneity. Results from capillary tube models rely on cross-sectional tube shapes and hydrate pore habits, thus are appropriate only for sediments with uniform hydrate distribution and known hydrate pore character. Given our pore network modeling results showing that accumulating hydrate in sediments decreases sediment porosity and increases hydraulic tortuosity, we propose a modified Kozeny-Carman model to characterize water permeability in hydrate-bearing sediments. This model agrees well with experimental results and can be easily implemented in reservoir simulators with no empirical variables other than Sh. Results are also relevant to flow through other natural sediments that undergo diagenesis, salt precipitation, or bio-clogging.

  14. Site Selection for DOE/JIP Gas Hydrate Drilling in the Northern Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Collett, T.S. (USGS); Riedel, M. (McGill Univ., Montreal, Quebec, Canada); Cochran, J.R. (Columbia Univ., Palisades, NY); Boswell, R.M.; Kumar, Pushpendra (Oil and Natural Gas Corporation Ltd., Navi Mumbai, India); Sathe, A.V. (Oil and Natural Gas Corporation Ltd., Uttaranchal, INDIA)

    2008-07-01

    Studies of geologic and geophysical data from the offshore of India have revealed two geologically distinct areas with inferred gas hydrate occurrences: the passive continental margins of the Indian Peninsula and along the Andaman convergent margin. The Indian National Gas Hydrate Program (NGHP) Expedition 01 was designed to study the occurrence of gas hydrate off the Indian Peninsula and along the Andaman convergent margin with special emphasis on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these two diverse settings. NGHP Expedition 01 established the presence of gas hydrates in Krishna- Godavari, Mahanadi and Andaman basins. The expedition discovered one of the richest gas hydrate accumulations yet documented (Site 10 in the Krishna-Godavari Basin), documented the thickest and deepest gas hydrate stability zone yet known (Site 17 in Andaman Sea), and established the existence of a fully-developed gas hydrate system in the Mahanadi Basin (Site 19).

  15. Pathogen inactivation technologies for cellular blood components: an update.

    Science.gov (United States)

    Schlenke, Peter

    2014-07-01

    Nowadays patients receiving blood components are exposed to much less transfusion-transmitted infectious diseases than three decades before when among others HIV was identified as causative agent for the acquired immunodeficiency syndrome and the transmission by blood or coagulation factors became evident. Since that time the implementation of measures for risk prevention and safety precaution was socially and politically accepted. Currently emerging pathogens like arboviruses and the well-known bacterial contamination of platelet concentrates still remain major concerns of blood safety with important clinical consequences, but very rarely with fatal outcome for the blood recipient. In contrast to the well-established pathogen inactivation strategies for fresh frozen plasma using the solvent-detergent procedure or methylene blue and visible light, the bench-to-bedside translation of novel pathogen inactivation technologies for cell-containing blood components such as platelets and red blood cells are still underway. This review summarizes the pharmacological/toxicological assessment and the inactivation efficacy against viruses, bacteria, and protozoa of each of the currently available pathogen inactivation technologies and highlights the impact of the results obtained from several randomized clinical trials and hemovigilance data. Until now in some European countries pathogen inactivation technologies are in in routine use for single-donor plasma and platelets. The invention and adaption of pathogen inactivation technologies for red blood cell units and whole blood donations suggest the universal applicability of these technologies and foster a paradigm shift in the manufacturing of safe blood.

  16. High pressure inactivation of Brettanomyces bruxellensis in red wine.

    Science.gov (United States)

    van Wyk, Sanelle; Silva, Filipa V M

    2017-05-01

    Brettanomyces bruxellensis ("Brett") is a major spoilage concern for the wine industry worldwide, leading to undesirable sensory properties. Sulphur dioxide, is currently the preferred method for wine preservation. However, due to its negative effects on consumers, the use of new alternative non-thermal technologies are increasingly being investigated. The aim of this study was to determine and model the effect of high pressure processing (HPP) conditions and yeast strain on the inactivation of "Brett" in Cabernet Sauvignon wine. Processing at 200 MPa for 3 min resulted in 5.8 log reductions. However higher pressure is recommended to achieve high throughput in the wine industry, for example >6.0 log reductions were achieved after 400 MPa for 5 s. The inactivation of B. bruxellensis is pressure and time dependent, with increased treatment time and pressure leading to increased yeast inactivation. It was also found that yeast strain had a significant effect on HPP inactivation, with AWRI 1499 being the most resistant strain. The Weibull model successfully described the HPP "Brett" inactivation. HPP is a viable alternative for the inactivation of B. bruxellensis in wine, with the potential to reduce the industry's reliance on sulphur dioxide.

  17. Thermal inactivation kinetics of β-galactosidase during bread baking.

    Science.gov (United States)

    Zhang, Lu; Chen, Xiao Dong; Boom, Remko M; Schutyser, Maarten A I

    2017-06-15

    In this study, β-galactosidase was utilized as a model enzyme to investigate the mechanism of enzyme inactivation during bread baking. Thermal inactivation of β-galactosidase was investigated in a wheat flour/water system at varying temperature-moisture content combinations, and in bread during baking at 175 or 205°C. In the wheat flour/water system, the thermostability of β-galactosidase increased with decreased moisture content, and a kinetic model was accurately fitted to the corresponding inactivation data (R(2)=0.99). Interestingly, the residual enzyme activity in the bread crust (about 30%) was hundredfold higher than that in the crumb (about 0.3%) after baking, despite the higher temperature in the crust throughout baking. This result suggested that the reduced moisture content in the crust increased the thermostability of the enzyme. Subsequently, the kinetic model reasonably predicted the enzyme inactivation in the crumb using the same parameters derived from the wheat flour/water system. However, the model predicted a lower residual enzyme activity in the crust compared with the experimental result, which indicated that the structure of the crust may influence the enzyme inactivation mechanism during baking. The results reported can provide a quantitative understanding of the thermal inactivation kinetics of enzyme during baking, which is essential to better retain enzymatic activity in bakery products supplemented with heat-sensitive enzymes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Design and Mechanism of Tetrahydrothiophene-based GABA Aminotransferase Inactivators

    Energy Technology Data Exchange (ETDEWEB)

    Le, Hoang V.; Hawker, Dustin D.; Wu, Rui; Doud, Emma; Widom, Julia; Sanishvili, Ruslan; Liu, Dali; Kelleher, Neil L.; Silverman, Richard B

    2015-04-08

    Low levels of gamma-aminobutyric acid (GABA), one of two major neurotransmitters that regulate brain neuronal activity, are associated with many neurological disorders, such as epilepsy, Parkinsons disease, Alzheimers disease, Huntingtons disease, and cocaine addiction. One of the main methods to raise the GABA level in human brain is to use small molecules that cross the bloodbrain barrier and inhibit the activity of gamma-aminobutyric acid aminotransferase (GABA-AT), the enzyme that degrades GABA. We have designed a series of conformationally restricted tetrahydrothiophene-based GABA analogues with a properly positioned leaving group that could facilitate a ring-opening mechanism, leading to inactivation of GABA-AT. One compound in the series is 8 times more efficient an inactivator of GABA-AT than vigabatrin, the only FDA-approved inactivator of GABA-AT. Our mechanistic studies show that the compound inactivates GABA-AT by a new mechanism. The metabolite resulting from inactivation does not covalently bind to amino acid residues of GABA-AT but stays in the active site via H-bonding interactions with Arg-192, a pi-pi interaction with Phe-189, and a weak nonbonded (SO)-O-...=C interaction with Glu-270, thereby inactivating the enzyme.

  19. Thermal Inactivation of Feline Calicivirus in Pet Food Processing.

    Science.gov (United States)

    Haines, J; Patel, M; Knight, A I; Corley, D; Gibson, G; Schaaf, J; Moulin, J; Zuber, S

    2015-12-01

    Extrusion is the most common manufacturing process used to produce heat-treated dry dog and cat food (pet food) for domestic use and international trade. Due to reoccurring outbreaks of notifiable terrestrial animal diseases and their impact on international trade, experiments were undertaken to demonstrate the effectiveness of heat-treated extruded pet food on virus inactivation. The impact of extrusion processing in a pet food matrix on virus inactivation has not been previously reported and very few inactivation studies have examined the thermal inactivation of viruses in complex food matrices. The feline calicivirus vaccine strain FCV F-9 was used as a surrogate model RNA virus pathogen. Small-scale heat inactivation experiments using animal-derived pet food raw materials showed that a > 4 log10 reduction (log10 R) in infectivity occurred at 70 °C prior to reaching the minimum extrusion manufacturing operating temperature of 100 °C. As anticipated, small-scale pressure studies at extrusion pressure (1.6 MPa) showed no apparent effect on FCV F-9 inactivation. Additionally, FCV F-9 was shown not to survive the acidic conditions used to produce pet food palatants of animal origin that are typically used as a coating after the extrusion process.

  20. Pathogen Inactivation Technologies for Cellular Blood Components: an Update

    Science.gov (United States)

    Schlenke, Peter

    2014-01-01

    Summary Nowadays patients receiving blood components are exposed to much less transfusion-transmitted infectious diseases than three decades before when among others HIV was identified as causative agent for the acquired immunodeficiency syndrome and the transmission by blood or coagulation factors became evident. Since that time the implementation of measures for risk prevention and safety precaution was socially and politically accepted. Currently emerging pathogens like arboviruses and the well-known bacterial contamination of platelet concentrates still remain major concerns of blood safety with important clinical consequences, but very rarely with fatal outcome for the blood recipient. In contrast to the well-established pathogen inactivation strategies for fresh frozen plasma using the solvent-detergent procedure or methylene blue and visible light, the bench-to-bedside translation of novel pathogen inactivation technologies for cell-containing blood components such as platelets and red blood cells are still underway. This review summarizes the pharmacological/toxicological assessment and the inactivation efficacy against viruses, bacteria, and protozoa of each of the currently available pathogen inactivation technologies and highlights the impact of the results obtained from several randomized clinical trials and hemovigilance data. Until now in some European countries pathogen inactivation technologies are in in routine use for single-donor plasma and platelets. The invention and adaption of pathogen inactivation technologies for red blood cell units and whole blood donations suggest the universal applicability of these technologies and foster a paradigm shift in the manufacturing of safe blood. PMID:25254027