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Sample records for adsorbed displacing methane

  1. Carbonaceous adsorbent regeneration and halocarbon displacement by hydrocarbon gases

    DOEpatents

    Senum, Gunnar I.; Dietz, Russell N.

    1994-01-01

    This invention describes a process for regeneration of halocarbon bearing carbonaceous adsorbents through which a carbonaceous adsorbent is contacted with hydrocarbon gases, preferably propane, butane and pentane at near room temperatures and at atmospheric pressure. As the hydrocarbon gases come in contact with the adsorbent, the hydrocarbons displace the halocarbons by physical adsorption. As a result of using this process, the halocarbon concentration and the hydrocarbon eluant is increased thereby allowing for an easier recovery of pure halocarbons. By using the process of this invention, carbonaceous adsorbents can be regenerated by an inexpensive process which also allows for subsequent re-use of the recovered halocarbons.

  2. Carbonaceous adsorbent regeneration and halocarbon displacement by hydrocarbon gases

    DOEpatents

    Senum, G.I.; Dietz, R.N.

    1994-04-05

    This invention describes a process for regeneration of halocarbon bearing carbonaceous adsorbents through which a carbonaceous adsorbent is contacted with hydrocarbon gases, preferably propane, butane and pentane at near room temperatures and at atmospheric pressure. As the hydrocarbon gases come in contact with the adsorbent, the hydrocarbons displace the halocarbons by physical adsorption. As a result of using this process, the halocarbon concentration and the hydrocarbon eluant is increased thereby allowing for an easier recovery of pure halocarbons. By using the process of this invention, carbonaceous adsorbents can be regenerated by an inexpensive process which also allows for subsequent re-use of the recovered halocarbons. 8 figures.

  3. Methane Recovery from Gaseous Mixtures Using Carbonaceous Adsorbents

    NASA Astrophysics Data System (ADS)

    Buczek, Bronisław

    2016-06-01

    Methane recovery from gaseous mixtures has both economical and ecological aspect. Methane from different waste gases like mine gases, nitrogenated natural gases and biogases can be treated as local source for production electric and heat energy. Also occurs the problem of atmosphere pollution with methane that shows over 20 times more harmful environmental effect in comparison to carbon dioxide. One of the ways utilisation such gases is enrichment of methane in the PSA technique, which requires appropriate adsorbents. Active carbons and carbon molecular sieve produced by industry and obtained in laboratory scale were examined as adsorbent for methane recuperation. Porous structure of adsorbents was investigated using densimetry measurements and adsorption of argon at 77.5K. On the basis of adsorption data, the Dubinin-Radushkevich equation parameters, micropore volume (Wo) and characteristics of energy adsorption (Eo) as well as area micropores (Smi) and BET area (SBET) were determined. The usability of adsorbents in enrichment of the methane was evaluated in the test, which simulate the basic stages of PSA process: a) adsorbent degassing, b) pressure raise in column by feed gas, c) cocurrent desorption with analysis of out flowing gas. The composition of gas phase was accepted as the criterion of the suitability of adsorbent for methane separation from gaseous mixtures. The relationship between methane recovery from gas mixture and texture parameters of adsorbents was found.

  4. [Activity of methane-oxidizing bacteria in the adsorbed state].

    PubMed

    Nesterov, A I; Nazarenko, A V

    1975-01-01

    Adsorption of pure cultures of methane oxidizing bacteria, Methylosinus trichosporium 20 and Methylococcus ucrainicus 21, on glass and coal was studied; the former strain was sorbed on both sorbents, the latter strain was sorbed on coal but not on glass. The rate of methane oxidation by the cells of adsorbed microorganisms was higher than in the case of free cells, and increased with a decrease in dimensions of the sorbent particles. PMID:1207502

  5. Spectroscopic observations of the displacement dynamics of physically adsorbed molecules-CO on C60

    NASA Astrophysics Data System (ADS)

    Yuan, Chunqing; Yates, John T.

    2016-10-01

    In this paper, we observed physically adsorbed CO molecules on C60 surface being displaced by impinging noble gas atoms (He, Ne, Ar, Kr), either through a dynamic displacement process or an exothermic replacement process, depending on their adsorption energies. This displacement mechanism could shift from one to the other depending on the surface coverage and temperature. Furthermore, rotational energy of the impinging molecules may also contribute to the dynamic displacement process by supplying additional energy.

  6. Contribution to the evaluation of density of methane adsorbed on activated carbon.

    PubMed

    Rodríguez-Reinoso, Francisco; Almansa, Cristina; Molina-Sabio, Miguel

    2005-11-01

    The adsorption isotherms of N(2) at -196 degrees C, CO(2) at 0 degrees C, and CH(4) at 25 degrees C on 35 activated carbons with a wide range of micropore volumes and pore size distributions have been compared to evaluate the density of adsorbed methane. Results indicate that methane is adsorbed in the micropores of the activated carbon with a density that is a function of the carbon porosity because methane is packed more compactly in narrow than in wide micropores. An experimental procedure is proposed to evaluate the density in both types of micropores as a function of pressure. Its application to these porous carbons indicates that density of adsorbed methane increases rapidly with pressure on narrow micropores, the increase becoming slower above 1.5 MPa. The value reached at 3 MPa is 0.21 g/cm(3), near that estimated as the limiting value, 0.23 g/cm(3). Density in wide micropores is low, 0.09 g/cm(3) at 3 MPa, but it continuously increases with pressure.

  7. Why can water cages adsorb aqueous methane? A potential of mean force calculation on hydrate nucleation mechanisms.

    PubMed

    Guo, Guang-Jun; Li, Meng; Zhang, Yi-Gang; Wu, Chang-Hua

    2009-11-28

    By performing constrained molecular dynamics simulations in the methane-water system, we successfully calculated the potential of mean force (PMF) between a dodecahedral water cage (DWC) and dissolved methane for the first time. As a function of the distance between DWC and methane, this is characterized by a deep well at approximately 6.2 A and a shallow well at approximately 10.2 A, separated by a potential barrier at approximately 8.8 A. We investigated how the guest molecule, cage rigidity and the cage orientation affected the PMF. The most important finding is that the DWC itself strongly adsorbs methane and the adsorption interaction is independent of the guests. Moreover, the activation energy of the DWC adsorbing methane is comparable to that of hydrogen bonds, despite differing by a factor of approximately 10% when considering different water-methane interaction potentials. We explain that the cage-methane adsorption interaction is a special case of the hydrophobic interaction between methane molecules. The strong net attraction in the DWC shell with radii between 6.2 and 8.8 A may act as the inherent driving force that controls hydrate formation. A cage adsorption hypothesis for hydrate nucleation is thus proposed and discussed. PMID:19890529

  8. Why can water cages adsorb aqueous methane? A potential of mean force calculation on hydrate nucleation mechanisms.

    PubMed

    Guo, Guang-Jun; Li, Meng; Zhang, Yi-Gang; Wu, Chang-Hua

    2009-11-28

    By performing constrained molecular dynamics simulations in the methane-water system, we successfully calculated the potential of mean force (PMF) between a dodecahedral water cage (DWC) and dissolved methane for the first time. As a function of the distance between DWC and methane, this is characterized by a deep well at approximately 6.2 A and a shallow well at approximately 10.2 A, separated by a potential barrier at approximately 8.8 A. We investigated how the guest molecule, cage rigidity and the cage orientation affected the PMF. The most important finding is that the DWC itself strongly adsorbs methane and the adsorption interaction is independent of the guests. Moreover, the activation energy of the DWC adsorbing methane is comparable to that of hydrogen bonds, despite differing by a factor of approximately 10% when considering different water-methane interaction potentials. We explain that the cage-methane adsorption interaction is a special case of the hydrophobic interaction between methane molecules. The strong net attraction in the DWC shell with radii between 6.2 and 8.8 A may act as the inherent driving force that controls hydrate formation. A cage adsorption hypothesis for hydrate nucleation is thus proposed and discussed.

  9. Experiments on Methane Displacement by Carbon Dioxide in Large Coal Specimens

    NASA Astrophysics Data System (ADS)

    Liang, Weiguo; Zhao, Yangsheng; Wu, Di; Dusseault, Maurice B.

    2011-09-01

    Carbon dioxide (CO2) is considered to be the most important greenhouse gas in terms of overall effect. CO2 geological storage in coal beds is of academic and industrial interest because of economic synergies between greenhouse gas sequestration and coal bed methane (CH4) recovery by displacement/adsorption. Previously, most work focused on either theoretical analyses and mathematical simulations or gas adsorption-desorption experiments using coal particles of millimeter size or smaller. Those studies provided basic understanding of CH4 recovery by CO2 displacement in coal fragments, but more relevant and realistic investigations are still rare. To study the processes more realistically, we conducted experimental CH4 displacement by CO2 and CO2 sequestration with intact 100 × 100 × 200 mm coal specimens. The coal specimen permeability was measured first, and results show that the permeability of the specimen is different for CH4 and CO2; the CO2 permeability was found to be at least two orders of magnitude greater than that for CH4. Simultaneously, a negative exponential relationship between the permeability and the applied mean stress on the specimen was found. Under the experimental stress conditions, 17.5-28.0 volumes CO2 can be stored in one volume of coal, and the displacement ratio CO2-CH4 is as much as 7.0-13.9. The process of injection, adsorption and desorption, displacement, and output of gases proceeds smoothly under an applied constant pressure differential, and the CH4 content in the output gas amounted to 20-50% at early stages, persisting to 10-16% during the last stage of the experiments. Production rate and CH4 fraction are governed by complex factors including initial CH4 content, the pore and fissure fabric of the coal, the changes in this fabric as the result of differential adsorption of CO2, the applied stress, and so on. During CO2 injection and CH4 displacement, the coal can swell from effects of gas adsorption and desorption, leading to

  10. Displacement behavior of CH4 adsorbed on coals by injecting pure CO2, N2, and CO2 N2 mixture

    NASA Astrophysics Data System (ADS)

    Shimada, Sohei; Li, Huoyin; Oshima, Yoshito; Adachi, Kazuhide

    2005-11-01

    Gas adsorption isotherms of Akabira coals were established for pure carbon dioxide (CO2), methane (CH4), and nitrogen (N2). Experimental data fit well into the Langmuir model. The ratio of sorption capacity of CO2, CH4, and N2 is 8.5:3.5:1 at a lower pressure (1.2 MPa) regime and becomes 5.5:2:1 when gas pressure increases to 6.0 MPa. The difference in sorption capacity of these three gases is explained by differences in the density of the three gases with increasing pressure. A coal methane system partially saturated with CH4 at 2.4 MPa adsorption pressure was experimentally studied. Desorption behavior of CH4 by injecting pure CO2 (at 3.0, 4.0, 5.0, and 6.0 MPa), and by injecting the CO2 N2 mixture and pure N2 (at 3.0 and 6.0 MPa) were evaluated. Results indicate that the preferential sorption property of coal for CO2 is significantly higher than that for CH4 or N2. CO2 injection can displace almost all of the CH4 adsorbed on coal. When modeling the CH4 CO2 binary and CH2 CO2 N2 ternary adsorption system by using the extended Langmuir (EL) equation, the EL model always over-predicted the sorbed CO2 value with a lower error, while under-predicting the sorbed CH4 with a higher error. A part of CO2 may dissolve into the solid organic structure of coal, besides its competitive adsorption with other gases. According to this explanation, the EL coefficients of CO2 in EL equation were revised. The revised EL model proved to be very accurate in predicting sorbed ratio of multi-component gases on coals.

  11. A Sea Floor Methane Hydrate Displacement Experiment Using N2 Gas

    NASA Astrophysics Data System (ADS)

    Brewer, P. G.; Peltzer, E. T.; Walz, P. M.; Zhang, X.; Hester, K.

    2009-12-01

    The production of free methane gas from solid methane hydrate accumulations presents a considerable challenge. The presently preferred procedure is pressure reduction whereby the relief of pressure to a condition outside the hydrate phase boundary creates a gas phase. The reaction is endothermic and thus a problematic water ice phase can form if the extraction of gas is too rapid, limiting the applicability of this procedure. Additionally, the removal of the formation water in contact with the hydrate phase is required before meaningful pressure reduction can be attained -- and this can take time. An alternate approach that has been suggested is the injection of liquid CO2 into the formation, thereby displacing the formation water. Formation of a solid CO2 hydrate is thermodynamically favored under these conditions. Competition between CH4 and CO2 for the hydrate host water molecules can occur displacing CH4 from the solid to the gas phase with formation of a solid CO2 hydrate. We have investigated another alternate approach with displacement of the surrounding bulk water phase by N2 gas, resulting in rapid release of CH4 gas and complete loss of the solid hydrate phase. Our experiment was carried out at the Southern Summit of Hydrate Ridge, offshore Oregon, at 780m depth. There we harvested hydrate fragments from surficial sediments using the robotic arm of the ROV Doc Ricketts. Specimens of the hydrate were collected about 1m above the sediment surface in an inverted funnel with a mesh covered neck as they floated upwards. The accumulated hydrate was transferred to an inverted glass cylinder, and N2 gas was carefully injected into this container. Displacement of the water phase occurred and when the floating hydrate material approached the lower rim the gas injection was stopped and the cylinder placed upon a flat metal plate effectively sealing the system. We returned to this site after 7 days to measure progress, and observed complete loss of the hydrate phase

  12. Competition between Displacement and Dissociation of a Strong Acid Compared to a Weak Acid Adsorbed on Silica Particle Surfaces: The Role of Adsorbed Water.

    PubMed

    Fang, Yuan; Tang, Mingjin; Grassian, Vicki H

    2016-06-16

    The adsorption of nitric (HNO3) and formic (HCOOH) acids on silica particle surfaces and the effect of adsorbed water have been investigated at 296 K using transmission FTIR spectroscopy. Under dry conditions, both nitric and formic acids adsorb reversibly on silica. Additionally, the FTIR spectra show that both of these molecules remain in the protonated form. At elevated relative humidities (RH), adsorbed water competes both for surface adsorption sites with these acids as well as promotes their dissociation to hydronium ions and the corresponding anions. Compared to HNO3, the extent of dissociation is much smaller for HCOOH, very likely because it is a weaker acid. This study provides valuable insights into the interaction of HNO3 and HCOOH with silica surface on the molecular level and further reveals the complex roles of surface-adsorbed water in atmospheric heterogeneous chemistry of mineral dust particles-many of these containing silica.

  13. Competition between Displacement and Dissociation of a Strong Acid Compared to a Weak Acid Adsorbed on Silica Particle Surfaces: The Role of Adsorbed Water.

    PubMed

    Fang, Yuan; Tang, Mingjin; Grassian, Vicki H

    2016-06-16

    The adsorption of nitric (HNO3) and formic (HCOOH) acids on silica particle surfaces and the effect of adsorbed water have been investigated at 296 K using transmission FTIR spectroscopy. Under dry conditions, both nitric and formic acids adsorb reversibly on silica. Additionally, the FTIR spectra show that both of these molecules remain in the protonated form. At elevated relative humidities (RH), adsorbed water competes both for surface adsorption sites with these acids as well as promotes their dissociation to hydronium ions and the corresponding anions. Compared to HNO3, the extent of dissociation is much smaller for HCOOH, very likely because it is a weaker acid. This study provides valuable insights into the interaction of HNO3 and HCOOH with silica surface on the molecular level and further reveals the complex roles of surface-adsorbed water in atmospheric heterogeneous chemistry of mineral dust particles-many of these containing silica. PMID:27220375

  14. Effects of Adsorbed Gases on the Physical and Transport Properties of Low-Rank Coal, PRB, WY: Implications for Carbon Sequestration and Enhanced Coalbed Methane Recovery

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Zoback, M. D.; Hagin, P. N.

    2010-12-01

    When CO2 is injected into unminable coalbeds, it has the potential to enhance the amount of methane production (ECBM) and to geologically sequester CO2 as an adsorbed phase. In this study we study the effects of adsorption of He, N2, CH4 and CO2, on the mechanical and flow properties of sub-bituminous coal from the Powder River Basin (PRB) on both intact and crushed samples. The coal samples were vacuum dried before each test, then saturated by each test gas at a series of either increasing pore pressure or increasing effective stress until steady state was reached. Thus, the amount of adsorption can be measured as a function of pore pressure Permeability was measured as a function of effective stress. Preliminary results show that the adsorption of CO2 is twice as large as CH4, and almost four times that of N2. Hysteresis is observed among pure component adsorption and desorption isotherms which are characterized Langmuir-type adsorption isotherms. Permeability decreases with increasing effective stress for He, CH4 and CO2. At constant effective stress, permeability decreases when the saturating gas changes from He to CH4 and CO2. Hysteresis of permeability with increasing and decreasing effective stress is not observed in crushed samples. The coal swells when CH4 displaces He and swells more when CO2 displaces He. Viscoplastic creep behavior is observed in the presence of CH4 and CO2 with both intact and crushed samples, which may affect maintaining permeability for long-term CO2 injection. Adsorption Isotherm of Crushed Coal Sample, WY Permeability as a function of effective stress with different gas saturation

  15. Heat and mass transfer effects during displacement of deepwater methane hydrate to the surface of Lake Baikal

    NASA Astrophysics Data System (ADS)

    Egorov, Alexander V.; Nigmatulin, Robert I.; Rozhkov, Aleksey N.

    2016-06-01

    The present paper focuses on heat and mass exchange processes in methane hydrate fragments during in situ displacement from the gas hydrate stability zone (GHSZ) to the water surface of Lake Baikal. After being extracted from the methane hydrate deposit at the lakebed, hydrate fragments were placed into a container with transparent walls and a bottom grid. There were no changes in the hydrate fragments during ascent within the GHSZ. The water temperature in the container remained the same as that of the ambient water (~3.5 °C). However, as soon as the container crossed the upper border of the GHSZ, first signs of hydrate decomposition and transformation into free methane gas were observed. The gas filled the container and displaced water from it. At 300 m depth, the upper and lower thermometers in the container simultaneously recorded noticeable decreases of temperature. The temperature in the upper part of the container decreased to -0.25 °C at about 200 m depth, after which the temperature remained constant until the water surface was reached. The temperature at the bottom of the container reached -0.25 °C at about 100 m depth, after which it did not vary during further ascent. These observed effects could be explained by the formation of a gas phase in the container and an ice layer on the hydrate surface caused by heat consumption during hydrate decomposition (self-preservation effect). However, steady-state simulations suggest that the forming ice layer is too thin to sustain the hydrate internal pressure required to protect the hydrate from decomposition. Thus, the mechanism of self-preservation remains unclear.

  16. Inelastic neutron scattering (INS) observations of rotational tunneling within partially deuterated methane monolayers adsorbed on MgO(1 0 0) surfaces

    NASA Astrophysics Data System (ADS)

    Hicks, Andy S.; Larese, J. Z.

    2013-12-01

    High resolution inelastic neutron scattering (INS) measurements of the low temperature (T ∼ 2.0 K) rotational dynamics of isotopically substituted methane monolayers adsorbed on MgO(1 0 0) are presented. These spectra, obtained using BASIS at SNS, represent the most detailed measurements available for surface-adsorbed monolayer films of methane. Distinct excitations are readily observed at 15, 31, 45 and 127 μeV for the CH2D2 on MgO monolayer and at 40, 51, 95 and 138 μeV for CH3D/MgO. These features are attributed to tunneling transitions between sublevels within the ground librational state and are interpreted using the pocket state (PS) formalism first proposed by Hüller. This theoretical analysis employs the findings of earlier studies of CH4 on MgO(1 0 0) which suggest that molecules adsorb with their C2v axes normal to the surface plane. The comparison between theory and experiment provides direct insight into the impact of molecular versus surface symmetry on the observed tunneling spectra.

  17. Acoustic emission and volumetric strain induced in coal by the displacement sorption of methane and carbone dioxide

    NASA Astrophysics Data System (ADS)

    Majewska, Zofia; Ziętek, Jerzy

    2008-06-01

    The aim of this study was to assess whether acoustic emission (AE) could carry information on preferential sorption/desorption of CH4 or CO2 in coal. AE and expansion/contraction of two nearly identical cylindrical coal samples were continuously monitored during displacement sorption experiments. One sample was subjected to presorption of CH4, followed by sorption of CH4/CO2 mixture. With the other one, presorption of CO2 preceded sorption of the mixture. The results obtained are the following: first, AE and stain kinetics show that the affinity of the coal tested is higher for CO2 than for CH4; second, methane is preferentially desorbed after presorption of CH4 — sorption of mixture of CH4 and CO2; third, during displacement sorption, kinetics of AE and sample swelling/shrinkage bring out the importance of presorption and the sorbate used. It matters whether the coal is first exposed to CH4 or to CO2. The present study has demonstrated that injection of CO2 into the coal previously exposed to CH4 causes considerable swelling of the coal. On desorption after CH4/CO2 exchange sorption, initial shrinkage is followed by swelling of the coal. These results could have implications for the sequestration of CO2 in coal seams and CH4 recovery from coalbeds (ECBM). Swelling/shrinkage of the coal matrix should be included in models used to predict coal permeability and gas flow rates. They also show that the AE technique can give more insights into coal matrix-gas interactions.

  18. Enhanced coalbed methane recovery

    SciTech Connect

    Mazzotti, M.; Pini, R.; Storti, G.

    2009-01-15

    The recovery of coalbed methane can be enhanced by injecting CO{sub 2} in the coal seam at supercritical conditions. Through an in situ adsorption/desorption process the displaced methane is produced and the adsorbed CO{sub 2} is permanently stored. This is called enhanced coalbed methane recovery (ECBM) and it is a technique under investigation as a possible approach to the geological storage of CO{sub 2} in a carbon dioxide capture and storage system. This work reviews the state of the art on fundamental and practical aspects of the technology and summarizes the results of ECBM field tests. These prove the feasibility of ECBM recovery and highlight substantial opportunities for interdisciplinary research at the interface between earth sciences and chemical engineering.

  19. Natural gas cleanup: Evaluation of a molecular sieve carbon as a pressure swing adsorbent for the separation of methane/nitrogen mixtures

    SciTech Connect

    Grimes, R.W.

    1994-06-01

    This report describes the results of a preliminary evaluation to determine the technical feasibility of using a molecular sieve carbon manufactured by the Takeda Chemical Company of Japan in a pressure owing adsorption cycle for upgrading natural gas (methane) contaminated with nitrogen. Adsorption tests were conducted using this adsorbent in two, four, and five-step adsorption cycles. Separation performance was evaluated in terms of product purity, product recovery, and sorbent productivity for all tests. The tests were conducted in a small, single-column adsorption apparatus that held 120 grams of the adsorbent. Test variables included adsorption pressure, pressurization rate, purge rate and volume, feed rate, and flow direction in the steps from which the product was collected. Sorbent regeneration was accomplished by purging the column with the feed gas mixture for all but one test series where a pure methane purge was used. The ratio between the volumes of the pressurization gas and the purge gas streams was found to be an important factor in determining separation performance. Flow rates in the various cycle steps had no significant effect. Countercurrent flow in the blow-down and purge steps improved separation performance. Separation performance appears to improve with increasing adsorption pressure, but because there are a number of interrelated variables that are also effected by pressure, further testing will be needed to verify this. The work demonstrates that a molecular sieve carbon can be used to separate a mixture of methane and nitrogen when used in a pressure swing cycle with regeneration by purge. Further work is needed to increase product purity and product recovery.

  20. Structural features of polymer adsorbent LiChrolut EN and interfacial behavior of water and water/organic mixtures.

    PubMed

    Gun'ko, V M; Turov, V V; Zarko, V I; Nychiporuk, Y M; Goncharuk, E V; Pakhlov, E M; Yurchenko, G R; Kulik, T V; Palyanytsya, B B; Borodavka, T V; Krupskaya, T V; Leboda, R; Skubiszewska-Zieba, J; Osovskii, V D; Ptushinskii, Y G; Turov, A V

    2008-07-01

    The structural and adsorption characteristics of polymer adsorbent LiChrolut EN and the behavior of adsorbed water and water/organic mixtures were studied using adsorption, microcalorimetry, transmission and scanning electron microscopy, mass spectrometry, infrared spectroscopy, 1H NMR spectroscopy with layer-by-layer freezing-out of liquids (190-273 K), and thermally stimulated depolarization current method (90-265 K). This adsorbent is characterized by large specific surface area (approximately 1500 m2/g) and pore volume (0.83 cm3/g) with a major contribution of narrow pores (R<10 nm) of a complicated shape (long hysteresis loop is in nitrogen adsorption-desorption isotherm). The adsorbent includes aromatic and aliphatic structures and oxygen-containing functionalities and can effectively adsorb organics and water/organic mixtures. On co-adsorption of water and organics (dimethyl sulfoxide, chloroform, methane), there is a weak influence of one on another adsorbate due to their poor mixing in pores. Weakly polar chloroform displaces a fraction of water from narrow pores. These effects can explain high efficiency of the adsorbent in solid-phase extraction of organics from aqueous solutions. The influence of structural features of several carbon and polymer adsorbents on adsorbed nitrogen, water and water/organics is compared on the basis of the adsorption and 1H NMR data. PMID:18440015

  1. Use of chloroflurocarbons as internal standards for the measurement of atmospheric non-methane volatile organic compounds sampled onto solid adsorbent cartridges.

    PubMed

    Karbiwnyk, Christine M; Mills, Craig S; Helmig, Detlev; Birks, John W

    2003-03-01

    Solid adsorbents have proven useful for determining the vertical profiles of volatile organic compounds (VOCs) using sampling platforms such as balloons, kites, and light aircraft, and those profiles provide valuable information about the sources, sinks, transformations, and transport of atmospheric VOCs. One of the largest contributions to error in VOC concentrations is the estimation of the volume of air sampled on the adsorbent cartridge. These errors arise from different sources, such as variations in pumping flow rates from changes in ambient temperature and pressure with altitude, and decrease in the sampling pump battery power. Another significant source for sampling rate variations are differences in the flow resistance of individual sampling cartridges. To improve the accuracy and precision of VOC measurements, the use of ambient chlorofluorocarbons (CFCs) as internal standards was investigated. A multibed solid adsorbent, AirToxic (Supelco), was chosen for its wide sampling range (C3-C12). Analysis was accomplished by thermal desorption and dual detection GC/FID/ECD, resulting in sensitive and selective detection of both VOCs and CFCs in the same sample. Long-lived chlorinated compounds (CFC-11, CFC-12, CFC-113, CCl4 and CH3CCl3) banned by the Montreal Protocol and subsequent amendments were studied for their ability to predict sample volumes using both ground-based and vertical profiling platforms through the boundary layer and free troposphere. Of these compounds, CFC-113 and CCl4 were found to yield the greatest accuracy and precision for sampling volume determination. Use of ambient CFC-113 and CCl4 as internal standards resulted in accuracy and precision of generally better than 10% for the prediction of sample volumes in ground-, balloon-, and aircraft-based measurements. Consequently, use of CFCs as reference compounds can yield a significant improvement of accuracy and precision for ambient VOC measurements in situations where accurate flow

  2. Use of chloroflurocarbons as internal standards for the measurement of atmospheric non-methane volatile organic compounds sampled onto solid adsorbent cartridges.

    PubMed

    Karbiwnyk, Christine M; Mills, Craig S; Helmig, Detlev; Birks, John W

    2003-03-01

    Solid adsorbents have proven useful for determining the vertical profiles of volatile organic compounds (VOCs) using sampling platforms such as balloons, kites, and light aircraft, and those profiles provide valuable information about the sources, sinks, transformations, and transport of atmospheric VOCs. One of the largest contributions to error in VOC concentrations is the estimation of the volume of air sampled on the adsorbent cartridge. These errors arise from different sources, such as variations in pumping flow rates from changes in ambient temperature and pressure with altitude, and decrease in the sampling pump battery power. Another significant source for sampling rate variations are differences in the flow resistance of individual sampling cartridges. To improve the accuracy and precision of VOC measurements, the use of ambient chlorofluorocarbons (CFCs) as internal standards was investigated. A multibed solid adsorbent, AirToxic (Supelco), was chosen for its wide sampling range (C3-C12). Analysis was accomplished by thermal desorption and dual detection GC/FID/ECD, resulting in sensitive and selective detection of both VOCs and CFCs in the same sample. Long-lived chlorinated compounds (CFC-11, CFC-12, CFC-113, CCl4 and CH3CCl3) banned by the Montreal Protocol and subsequent amendments were studied for their ability to predict sample volumes using both ground-based and vertical profiling platforms through the boundary layer and free troposphere. Of these compounds, CFC-113 and CCl4 were found to yield the greatest accuracy and precision for sampling volume determination. Use of ambient CFC-113 and CCl4 as internal standards resulted in accuracy and precision of generally better than 10% for the prediction of sample volumes in ground-, balloon-, and aircraft-based measurements. Consequently, use of CFCs as reference compounds can yield a significant improvement of accuracy and precision for ambient VOC measurements in situations where accurate flow

  3. Adsorbent phosphates

    NASA Technical Reports Server (NTRS)

    Watanabe, S.

    1983-01-01

    An adsorbent which uses as its primary ingredient phosphoric acid salts of zirconium or titanium is presented. Production methods are discussed and several examples are detailed. Measurements of separating characteristics of some gases using the salts are given.

  4. Phase states of methane in fossil coals

    NASA Astrophysics Data System (ADS)

    Alexeev, A. D.; Vasylenko, T. A.; Ul'yanova, E. V.

    2004-06-01

    NMR measurements have revealed that methane can exist in coal samples in the state of solid solution rather than only adsorbed gas, opening new ways to prevention of gas dynamic accidents in underground coal mines and true estimation of coalbed methane resources. Understanding molecular structure of coal constituents and forms of methane occurrence in coal is the only way of extracting safely either coal or methane. We had studied nuclear magnetic resonance lines in various coals at room or low temperatures and have found that there exist three species of methane molecules differing in molecular mobility. Based on estimated diffusion parameters, these species were attributed to free methane, adsorbed methane, and solid solution of methane in crystalline coal substance. While first two phases are well known and can be analyzed by many different techniques, the last one hardly can be studied by methods other than NMR, resulting in inadequate estimations of methane resources.

  5. A multicomponent, two-phase-flow model for CO{sub 2} storage and enhanced coalbed-methane recovery

    SciTech Connect

    Seto, C.J.; Jessen, K.; Orr, F.M.

    2009-03-15

    Injection of CO{sub 2} into deep unminable coal seams is an option for geological storage of CO{sub 2} and may enhance the recovery of CH{sub 4} in these systems, making coal reservoirs interesting candidates for sequestration. New analytical solutions are presented for two-phase, three- and four-component flow with volume change on mixing in adsorbing systems. We analyze the simultaneous flow of water and gas containing multiple adsorbing components. The displacement problem is solved by the method of characteristics. Mixtures of N{sub 2}, CH{sub 4}, CO{sub 2}, and H{sub 2}O are used to represent enhanced coalbed-methane (ECBM) recovery processes. The displacement behavior is demonstrated to be strongly dependent on the relative adsorption strength of the gas components. In ternary systems, two types of solutions result. When a gas rich in CO{sub 2} displaces a less strongly adsorbing gas (such as CH{sub 4}), a shock solution is obtained. As the injected gas propagates through the system, CO{sub 2} is removed from the mobile phase by adsorption, while desorbed gas propagates ahead of the CO{sub 2} front. The adsorption of CO{sub 2} reduces the flow velocity of the injected gas, delaying breakthrough and allowing for more CO{sub 2} to be sequestered per volume of CH{sub 4} produced. For injection gases rich in N{sub 2}, a decrease in partial pressure is required to displace the preferentially adsorbed CH{sub 4} and a rarefaction solution results. In quaternary displacements with injection-gas mixtures of CO{sub 2} and N{sub 2}, the relative adsorption strength of the components results in solutions that exhibit features of both the N{sub 2}-rich and CO{sub 2}-rich ternary displacements. Analytical solutions for ECBM recovery processes provide insight into the complex interplay of adsorption, phase behavior, and convection.

  6. Tetraperchlorate of methane

    NASA Technical Reports Server (NTRS)

    Schack, C. J.

    1972-01-01

    The preparation of the tetraperchlorate of methane (TPM) was attempted. Displacement of halogen from carbon tetrahalides was accomplished with either CCl4 or CBr4 using the halogen perchlorates, ClOClO3, and BOClO3. Although the displacement process was successful, the generated carbon perchlorate intermediates were not isolated. Instead, these species decomposed to COCl2, CO2, and Cl2O7. The vigorous displacement reaction that often occurred required moderation. Fluorocarbon solvents and chlorine perchlorate were successfully tested for compatibility, permitting their use in these synthetic reactions. While the sought for moderating effect was obtained, the net result of the displacement of halogen from CX sub 4 substrates was the same as before. Thus only CO2, COCl2, and Cl2O7 were isolated.

  7. Modeling adsorption: Investigating adsorbate and adsorbent properties

    NASA Astrophysics Data System (ADS)

    Webster, Charles Edwin

    1999-12-01

    Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas

  8. Final report for the Iowa Livestock Industry Waste Characterization and Methane Recovery Information Dissemination Project

    SciTech Connect

    Garrison, M.V.; Richard, Thomas L

    2001-11-13

    This report summarizes analytical methods, characterizes Iowa livestock wastes, determines fossil fuel displacement by methane use, assesses the market potential, and offers recommendations for the implementation of methane recovery technologies.

  9. Lateral displacement and rotational displacement sensor

    DOEpatents

    Duden, Thomas

    2014-04-22

    A position measuring sensor formed from opposing sets of capacitor plates measures both rotational displacement and lateral displacement from the changes in capacitances as overlapping areas of capacitors change. Capacitances are measured by a measuring circuit. The measured capacitances are provided to a calculating circuit that performs calculations to obtain angular and lateral displacement from the capacitances measured by the measuring circuit.

  10. Methane conversion

    SciTech Connect

    Jones, C.A.; Leonard, J.J.; Sofranko, J.A.

    1984-04-17

    Another version of Arco's process for reforming methane or natural gas into a synthesis gas uses bismuth oxide as the reforming agent; it also requires no nickel or noble metal catalyst. The methane-containing gas contacts bismuth oxide at temperatures of 900/sup 0/-1560/sup 0/F. The oxide is reduced by methane and easily regenerated with an oxygen-containing gas. The oxide Bi/sub 2/O/sub 3/ is a particularly effective synthesizing agent.

  11. Molecular Adsorber Coating

    NASA Technical Reports Server (NTRS)

    Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

    2011-01-01

    A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

  12. Sinking methane.

    PubMed

    Reay, David S

    2003-02-01

    Concentrations of the powerful greenhouse gas, methane, in our atmosphere have doubled since the beginning of the industrial age. Reducing these levels is a vital part of global efforts to combat global warming. Could we make use of the Earth's own methane sinks?

  13. Activated carbon monoliths for methane storage

    NASA Astrophysics Data System (ADS)

    Chada, Nagaraju; Romanos, Jimmy; Hilton, Ramsey; Suppes, Galen; Burress, Jacob; Pfeifer, Peter

    2012-02-01

    The use of adsorbent storage media for natural gas (methane) vehicles allows for the use of non-cylindrical tanks due to the decreased pressure at which the natural gas is stored. The use of carbon powder as a storage material allows for a high mass of methane stored for mass of sample, but at the cost of the tank volume. Densified carbon monoliths, however, allow for the mass of methane for volume of tank to be optimized. In this work, different activated carbon monoliths have been produced using a polymeric binder, with various synthesis parameters. The methane storage was studied using a home-built, dosing-type instrument. A monolith with optimal parameters has been fabricated. The gravimetric excess adsorption for the optimized monolith was found to be 161 g methane for kg carbon.

  14. Using specialized adsorbents for remediation

    SciTech Connect

    Hochmuth, D.P.; Grant, A.

    1995-11-01

    This paper describes two remediation case studies in which specialized adsorbents were used. In one case, the adsorbents were used to treat effluent from a soil vapor extraction system. In the other case, the adsorbents were used to treat air from a groundwater air stripper. The specialized adsorbents effectively removed volatile organic compounds from each air stream.

  15. Carbon fibre composite for ventilation air methane (VAM) capture.

    PubMed

    Thiruvenkatachari, Ramesh; Su, Shi; Yu, Xin Xiang

    2009-12-30

    Coal mine methane (CMM) is not only a hazardous greenhouse gas but is also a wasted energy resource, if not utilised. This paper evaluates a novel adsorbent material developed for capturing methane from ventilation air methane (VAM) gas in underground coal mines. The adsorbent material is a honeycomb monolithic carbon fibre composite (HMCFC) consisting of multiple parallel flow-through channels and the material exhibits unique features including low pressure drop, good mechanical properties, ability to handle dust-containing gas streams, good thermal and electrical conductivity and selective adsorption of gases. During this study, a series of HMCFC adsorbents (using different types of carbon fibres) were successfully fabricated. Experimental data demonstrated the proof-of-concept of using the HMCFC adsorbent to capture methane from VAM gas. The adsorption capacity of the HMCFC adsorbent was twice that of commercial activated carbon. Methane concentration of 0.56% in the inlet VAM gas stream is reduced to about 0.011% after it passes through the novel carbon fibre composite adsorbent material at ambient temperature and atmospheric pressure. This amounts to a maximum capture efficiency of 98%. These encouraging laboratory scale studies have prompted further large scale trials and economic assessment.

  16. Carbon fibre composite for ventilation air methane (VAM) capture.

    PubMed

    Thiruvenkatachari, Ramesh; Su, Shi; Yu, Xin Xiang

    2009-12-30

    Coal mine methane (CMM) is not only a hazardous greenhouse gas but is also a wasted energy resource, if not utilised. This paper evaluates a novel adsorbent material developed for capturing methane from ventilation air methane (VAM) gas in underground coal mines. The adsorbent material is a honeycomb monolithic carbon fibre composite (HMCFC) consisting of multiple parallel flow-through channels and the material exhibits unique features including low pressure drop, good mechanical properties, ability to handle dust-containing gas streams, good thermal and electrical conductivity and selective adsorption of gases. During this study, a series of HMCFC adsorbents (using different types of carbon fibres) were successfully fabricated. Experimental data demonstrated the proof-of-concept of using the HMCFC adsorbent to capture methane from VAM gas. The adsorption capacity of the HMCFC adsorbent was twice that of commercial activated carbon. Methane concentration of 0.56% in the inlet VAM gas stream is reduced to about 0.011% after it passes through the novel carbon fibre composite adsorbent material at ambient temperature and atmospheric pressure. This amounts to a maximum capture efficiency of 98%. These encouraging laboratory scale studies have prompted further large scale trials and economic assessment. PMID:19733967

  17. Regenerative adsorbent heat pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative adsorbent heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system and at least a portion of the heat of adsorption. A series of at least four compressors containing an adsorbent is provided. A large amount of heat is transferred from compressor to compressor so that heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  18. Breaking methane

    PubMed Central

    Rosenzweig, Amy C.

    2015-01-01

    The most powerful oxidant found in nature is compound Q, an enzymatic intermediate that oxidizes methane. New spectroscopic data have resolved the long-running controversy about Q’s chemical structure. PMID:25607367

  19. Harnessing methane

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    The total methane resource in hydrates—ice-like substances found in deep ocean sediments and Arctic permafrost—exceeds the energy content of all other fossil fuel resources,such as coal, oil, and conventional gas, according to the U.S. Geological Survey (USGS).The Methane Hydrate Research and Development Act, signed into law by U.S. President Bill Clinton on May 3, establishes a new federal commitment to developing methane hydrates, which has been touted as a potentially clean energy source that could make the U.S. less dependent on foreign sources of energy. The bill authorizes $47.5 million over five years for the Department of Energy to establish a federal methane hydrate research and development program.

  20. Adsorbent and adsorbent bed for materials capture and separation processes

    SciTech Connect

    Liu, Wei

    2011-01-25

    A method device and material for performing adsorption wherein a fluid mixture is passed through a channel in a structured adsorbent bed having a solid adsorbent comprised of adsorbent particles having a general diameter less than 100 um, loaded in a porous support matrix defining at least one straight flow channel. The adsorbent bed is configured to allow passage of a fluid through said channel and diffusion of a target material into said adsorbent under a pressure gradient driving force. The targeted molecular species in the fluid mixture diffuses across the porous support retaining layer, contacts the adsorbent, and adsorbs on the adsorbent, while the remaining species in the fluid mixture flows out of the channel.

  1. Trace contaminant studies of HSC adsorbent. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Yieh, D. T. N.

    1978-01-01

    The adsorption and desorption of fifteen trace contaminants on HSC (polyethylenimine coated acrylic ester) adsorbent were experimentally investigated with the following two objectives: to test the removal potential and the adsorption reversibility of the selected trace contaminants, and to test the effect a preadsorbed trace contaminant has on the CO2 adsorption capacity. The experimental method for acquiring the adsorption equilibrium data used is based on the volumetric (or displacement) concept of vacuum adsorption. From the experimental results, it was found that the HSC adsorbent has good adsorption potential for contaminants of alcohol compounds, esters, and benzene compounds; whereas, adsorption of ketone compounds, oxidizing and reducing agents are detrimental to the adsorbent. In addition, all liquid contaminants reduce the CO2 capacity of HSC adsorbent.

  2. UPGRADING METHANE USING ULTRA-FAST THERMAL SWING ADSORPTION

    SciTech Connect

    Anna Lee Tonkovich

    2004-01-01

    The purpose of this project is to design and demonstrate an approach to upgrade low-BTU methane streams from coal mines to pipeline-quality natural gas. The objective of Phase I of the project was to assess the feasibility of upgrading low-Btu methane streams using ultra-fast thermal swing adsorption (TSA) using Velocys' modular microchannel process technology. The project is on schedule and under budget. For Task 1.1, the open literature, patent information, and vendor contacts were surveyed to identify adsorbent candidates for experimental validation and subsequent demonstration in an MPT-based ultra-fast TSA separation for methane upgrading. The leading candidates for preferential adsorption of methane over nitrogen are highly microporous carbons. A Molecular Gate{trademark} zeolite from Engelhard Corporation has emerged as a candidate. For Task 1.2, experimental evaluation of adsorbents was initiated, and data were collected on carbon (MGN-101) from PICA, Inc. This carbon demonstrated a preferential capacity for methane over nitrogen, as well as a reasonable thermal swing differential capacity for a 90% methane and 10% nitrogen mixture. A similar methane swing capacity at 2 psig was measured. The mixture composition is relevant because gob gas contains nearly 85% methane and must be purified to 97% methane for pipeline quality.

  3. Hybrid molecular simulation of methane storage inside pillared graphene

    NASA Astrophysics Data System (ADS)

    Hassani, Atieh; Hamed Mosavian, Mohammad Taghi; Ahmadpour, Ali; Farhadian, Nafiseh

    2015-06-01

    In this study, a hybrid molecular dynamics—grand canonical Monte Carlo simulation is carried out to investigate the storage capacity of methane in a new nanostructure adsorbent called pillared graphene. This new nanostructure is composed of graphene sheets in parallel with vertical carbon nanotubes (CNTs), which act as their holders. The adsorption ability of this new structure is compared to graphene sheets to evaluate its potential for methane storage. The results show that in a specific adsorbent volume, applying pillared graphene increases the number of adsorbed methane up to 22% in comparison to graphene sheets. Given the application of various isotherm models such as Langmuir, Freundlich, Sips, and Toth and calculation of their parameters, it is predicted that methane adsorption on pillared graphene displays a heterogeneous behavior. Furthermore, the effects of geometry parameters such as CNTs diameter, the number of CNTs, and graphene sheets layer spacing on the methane uptake are investigated. The results show that the pillared graphene containing 1 CNT per 30 nm2 graphene sheet areas provides the best configuration for methane adsorption. This optimum structure is characterized by a small diameter of about 0.938 nm and an optimal layer spacing of about 1.2 nm. Finally, our results show that this kind of pillared structure can be suitable for methane storage.

  4. Adsorbed Natural Gas Storage in Optimized High Surface Area Microporous Carbon

    NASA Astrophysics Data System (ADS)

    Romanos, Jimmy; Rash, Tyler; Nordwald, Erik; Shocklee, Joshua Shawn; Wexler, Carlos; Pfeifer, Peter

    2011-03-01

    Adsorbed natural gas (ANG) is an attractive alternative technology to compressed natural gas (CNG) or liquefied natural gas (LNG) for the efficient storage of natural gas, in particular for vehicular applications. In adsorbants engineered to have pores of a few molecular diameters, a strong van der Walls force allows reversible physisorption of methane at low pressures and room temperature. Activated carbons were optimized for storage by varying KOH:C ratio and activation temperature. We also consider the effect of mechanical compression of powders to further enhance the volumetric storage capacity. We will present standard porous material characterization (BET surface area and pore-size distribution from subcritical N2 adsorption) and methane isotherms up to 250 bar at 293K. At sufficiently high pressure, specific surface area, methane binding energy and film density can be extracted from supercritical methane adsorption isotherms. Research supported by the California Energy Commission (500-08-022).

  5. Precision displacement reference system

    DOEpatents

    Bieg, Lothar F.; Dubois, Robert R.; Strother, Jerry D.

    2000-02-22

    A precision displacement reference system is described, which enables real time accountability over the applied displacement feedback system to precision machine tools, positioning mechanisms, motion devices, and related operations. As independent measurements of tool location is taken by a displacement feedback system, a rotating reference disk compares feedback counts with performed motion. These measurements are compared to characterize and analyze real time mechanical and control performance during operation.

  6. Selective removal of copper and lead ions by diethylenetriamine-functionalized adsorbent: behaviors and mechanisms.

    PubMed

    Liu, Changkun; Bai, Renbi; San Ly, Quan

    2008-03-01

    The selective removal of copper and lead ions from aqueous solutions by diethylenetriamine (DETA)-functionalized polymeric adsorbent was investigated. The adsorbent was prepared by amination of the micro-beads synthesized from glycidyl methacrylate and trimethylolpropane trimethacrylate co-polymerization (denoted as P-DETA). In the single metal species system (only copper or lead ions present), P-DETA was found to adsorb copper ions or lead ions significantly (with a slightly higher adsorption uptake capacity for lead ions than copper ions). However, P-DETA displayed an excellent selectivity in the adsorption of copper ions over lead ions in the binary metal species system (with both copper and lead ions present). It was also found that initially (or previously) adsorbed lead ions on P-DETA were displaced, even completely, by subsequently adsorbed copper ions from the solution but the case was not vice versa. The greater electronegativity of copper ions than lead ions was identified as the major factor that caused P-DETA to selectively adsorb copper ions over lead ions during competitive adsorption in the binary metal species system. It was speculated that the displacement of already adsorbed lead ions on P-DETA by subsequently adsorbed copper ions was through an adjacent attachment and repulsion mechanism. P-DETA has been shown to have the potential to be used as an effective adsorbent for the removal as well as selective recovery of heavy metal ions in water or wastewater treatment.

  7. Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials.

    PubMed

    Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Hoefman, Sven; De Vos, Paul; Boeckx, Pascal; Boon, Nico

    2014-04-01

    Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (~20 % (v/v)) and low (~100 ppmv) methane mixing ratios. Methylocystis parvus in autoclaved aerated concrete (AAC) exhibited the highest methane removal rate at high (28.5 ± 3.8 μg CH₄ g⁻¹ building material h⁻¹) and low (1.7 ± 0.4 μg CH₄ g⁻¹ building material h⁻¹) methane mixing ratio. Due to the higher volume of pores with diameter >5 μm compared to other materials tested, AAC was able to adsorb more bacteria which might explain for the higher methane removal observed. The total methane and carbon dioxide-carbon in the headspace was decreased for 65.2 ± 10.9 % when M. parvus in Ytong was incubated for 100 h. This study showed that immobilized MOB on building materials could be used to remove methane from the air and also act as carbon sink.

  8. Bowl inversion of surface-adsorbed sumanene.

    PubMed

    Jaafar, Rached; Pignedoli, Carlo A; Bussi, Giovanni; Aït-Mansour, Kamel; Groening, Oliver; Amaya, Toru; Hirao, Toshikazu; Fasel, Roman; Ruffieux, Pascal

    2014-10-01

    Bowl-shaped π-conjugated compounds offer the possibility to study curvature-dependent host-guest interactions and chemical reactivity in ideal model systems. For surface-adsorbed π bowls, however, only conformations with the bowl opening pointing away from the surface have been observed so far. Here we show for sumanene on Ag(111) that both bowl-up and bowl-down conformations can be stabilized. Analysis of the molecular layer as a function of coverage reveals an unprecedented structural phase transition involving a bowl inversion of one-third of the molecules. On the basis of scanning tunneling microscopy (STM) and complementary atomistic simulations, we develop a model that describes the observed phase transition in terms of a subtle interplay between inversion-dependent adsorption energies and intermolecular interactions. In addition, we explore the coexisting bowl-up and -down conformations with respect to host-guest binding of methane. STM reveals a clear energetic preference for methane binding to the concave face of sumanene. PMID:25181621

  9. A FORTRAN program for modeling methane gas desorption from coal

    NASA Astrophysics Data System (ADS)

    Nguyen, V. U.

    Coal has a strong affinity for methane gas, and the process of gas adsorption (or desorption) is modeled customarily by empirical relations between the amount of gas adsorbed (or desorbed) and time. In this paper, a new and unified theory formulated to depict the process and mechanism of methane gas transport in coal is presented. The theory is validated by conventional sorption tests on cylindrical cores, and its description coded in FORTRAN is presented.

  10. Adsorption Hysteresis and its Effect on CO2 Sequestration and Enhanced Coalbed Methane Recovery

    NASA Astrophysics Data System (ADS)

    Seto, C. J.; Tang, G. T.; Jessen, K.; Kovscek, A. R.; Orr, F. M.

    2006-12-01

    CO2 sequestration in coal reservoirs is a promising technology for reducing atmospheric CO2 concentrations. Of the candidates for geological sequestration, the physics of transport and sequestration in coal is the least well understood. Adsorption hysteresis has been observed for pure gas adsorption on some coals. It is manifest as desorption curves where the loading of gas on coal surfaces is greater than sorption at the same pressure. Current simulation technology does not have the functionality to incorporate this phenomenon that has a potentially great effect on sequestration in coalbeds. Understanding the interplay between adsorption and desorption of gas species, phase behaviour and convection is paramount to designing safe and effective sequestration projects. Our work integrates experiments and theory development. Isotherms of CH4, N2 and CO2 were measured on a sample of coal from the Powder River Basin, WY, for adsorption and desorption paths. Hysteresis was observed for all gases. Likewise, the displacment of methane by various mixtures of N2 and CO2 was also measured. Simultaneously, a model was developed to solve for the dispersion-free limit of convective transport in multiphase systems with adsorption, including the effects of volume change as components transfer from vapour to liquid and solid phases. Analytical solutions were obtained using the method of characteristics. These solutions were compared against corresponding solutions without adsorption hysteresis. For pure gas injection, in which the amount of adsorbed injected gas increases monotonically and the amount of adsorbed initial gas decreases monotonically, hysteresis effects were not observed. For injection gas mixtures of N2-CO2 displacing CH4, CO2 and N2 separated chromatographically and hysteresis effected breakthrough and bank arrival times as well as shifted overall component concentrations as the displacement progressed. When injection gas mixtures were rich in N2, the structures

  11. Advanced Triangulation Displacement Sensors

    NASA Technical Reports Server (NTRS)

    Poteet, Wade M.; Cauthen, Harold K.

    1996-01-01

    Advanced optoelectronic triangulation displacement sensors undergoing development. Highly miniaturized, more stable, more accurate, and relatively easy to use. Incorporate wideband electronic circuits suitable for real-time monitoring and control of displacements. Measurements expected to be accurate to within nanometers. In principle, sensors mass-produced at relatively low unit cost. Potential applications numerous. Possible industrial application in measuring runout of rotating shaft or other moving part during fabrication in "zero-defect" manufacturing system, in which measured runout automatically corrected.

  12. Internal displacement in Burma.

    PubMed

    Lanjouw, S; Mortimer, G; Bamforth, V

    2000-09-01

    The internal displacement of populations in Burma is not a new phenomenon. Displacement is caused by numerous factors. Not all of it is due to outright violence, but much is a consequence of misguided social and economic development initiatives. Efforts to consolidate the state by assimilating populations in government-controlled areas by military authorities on the one hand, while brokering cease-fires with non-state actors on the other, has uprooted civilian populations throughout the country. Very few areas in which internally displaced persons (IDPs) are found are not facing social turmoil within a climate of impunity. Humanitarian access to IDP populations remains extremely problematic. While relatively little information has been collected, assistance has been focused on targeting accessible groups. International concern within Burma has couched the problems of displacement within general development modalities, while international attention along its borders has sought to contain displacement. With the exception of several recent initiatives, few approaches have gone beyond assistance and engaged in the prevention or protection of the displaced.

  13. Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption

    SciTech Connect

    Anna Lee Tonkovich

    2005-07-01

    The purpose of this project is to design and demonstrate an approach to upgrade low-BTU methane streams from coal mines to pipeline-quality natural gas. The objective of Phase I of the project was to assess the technical feasibility and cost of upgrading low-BTU methane streams using ultra-fast thermal swing adsorption (TSA) using Velocys modular microchannel process technology. The objective of Phase II is to demonstrate the process at the bench-scale. Natural gas upgrading systems have six main unit operations: feed compressor, dehydration unit, nitrogen rejection unit, deoxygenator, carbon dioxide scrubber, and a sales compressor. The NRU is the focus of the development program, and a bench-scale demonstration has been initiated. The Velocys NRU system targets producing methane with greater than 96% purity and at least 90% recovery for final commercial operation. A preliminary cost analysis of the methane upgrading system, including the Velocys NRU, suggests that costs below $2.00 per million (MM) BTU methane may be achieved. The cost for a conventional methane upgrading system is well above $2.30 per MM BTU, as benchmarked in an Environmental Protection Agency study. The project is on schedule and on budget. Task 4, a bench-scale demonstration of the ultra-fast TSA system is complete. Rapid thermal swing of an adsorbent bed using microchannels has been successfully demonstrated and the separation of a 70% methane and 30% nitrogen was purified to 92% methane. The bench-scale demonstration unit was small relative to the system dead volume for the initial phase of experiments and a purge step was added to sweep the dead volume prior to desorbing the bed and measuring purity. A technical and economic feasibility assessment was completed in Task 3. The proposed Velocys technology appears feasible for the methane upgrading market. Evaluated categories include adsorbent selection, rapid-cycle valve selection, microchannel manufacturability assessment, and system

  14. Competitive adsorption, displacement, and transport of organic matter on iron oxide: II. Displacement and transport

    NASA Astrophysics Data System (ADS)

    Gu, Baohua; Mehlhorn, Tonia L.; Liang, Liyuan; McCarthy, John F.

    1996-08-01

    The competitive interactions between organic matter compounds and mineral surfaces are poorly understood, yet these interactions may play a significant role in the stability and co-transport of mineral colloids and/or environmental contaminants. In this study, the processes of competitive adsorption, displacement, and transport of Suwannee River natural organic matter (SR-NOM) are investigated with several model organic compounds in packed beds of iron oxide-coated quartz columns. Results demonstrated that strongly-binding organic compounds are competitively adsorbed and displace those weakly-bound organic compounds along the flow path. Among the four organic compounds studied, polyacrylic acid (PAA) appeared to be the most competitive, whereas SR-NOM was more competitive than phthalic and salycylic acids. The transport of SR-NOM is found to involve a complex competitive interaction and displacement of different NOM subcomponents. A diffuse adsorption and sharp desorption front (giving an appearance of irreversible adsorption) of the SR-NOM breakthrough curves are explained as being a result of the competitive time-dependent adsorption and displacement processes between different organic components within the SR-NOM. The stability and transport of iron oxide colloids varied as one organic component competitively displaces another. Relatively large quantities of iron oxide colloids are transported when the more strongly-binding PAA competitively displaces the weakly-binding SR-NOM or when SR-NOM competitively displaces phthalic and salicylic acids. Results of this study suggest that the chemical composition and hence the functional behavior of NOM (e.g., in stabilizing mineral colloids and in complexing contaminants) can change along its flow path as a result of the dynamic competitive interactions between heterogeneous NOM subcomponents. Further studies are needed to better define and quantify these NOM components as well as their roles in contaminant partitioning

  15. Water displacement mercury pump

    DOEpatents

    Nielsen, M.G.

    1984-04-20

    A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

  16. Water displacement mercury pump

    DOEpatents

    Nielsen, Marshall G.

    1985-01-01

    A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

  17. Optical displacement sensor

    DOEpatents

    Carr, Dustin W.

    2008-04-08

    An optical displacement sensor is disclosed which uses a vertical-cavity surface-emitting laser (VCSEL) coupled to an optical cavity formed by a moveable membrane and an output mirror of the VCSEL. This arrangement renders the lasing characteristics of the VCSEL sensitive to any movement of the membrane produced by sound, vibrations, pressure changes, acceleration, etc. Some embodiments of the optical displacement sensor can further include a light-reflective diffractive lens located on the membrane or adjacent to the VCSEL to control the amount of lasing light coupled back into the VCSEL. A photodetector detects a portion of the lasing light from the VCSEL to provide an electrical output signal for the optical displacement sensor which varies with the movement of the membrane.

  18. Record Methane Storage in Monolithic and Powdered Activated Carbons

    NASA Astrophysics Data System (ADS)

    Soo, Yuchoong; Nordwald, E.; Hester, B.; Romanos, J.; Isaacson, B.; Stalla, D.; Moore, D.; Kraus, M.; Burress, J.; Dohnke, E.; Pfeifer, P.

    2010-03-01

    The Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) has developed activated carbons from corn cob as adsorbent materials for methane gas storage by physisorption at low pressures. KOH activated carbons were compressed into carbon monolith using chemical binders. High pressure methane isotherms up to 250 bar at room temperature on monolithic and powdered activated carbons were measured gravimetrically and volumetrically. Record methane storage capacities of 250 g CH4/kg carbon and 130 g CH4/liter carbon at 35 bar and 293 K have been achieved. BET surface area, porosity, and pore size distributions were measured from sub-critical nitrogen isotherms. Pore entrances were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A prototype adsorbed natural gas (ANG) tank, loaded with carbon monoliths, was tested in Kansas City.

  19. Methane Hydrates: Chapter 8

    USGS Publications Warehouse

    Boswell, Ray; Yamamoto, Koji; Lee, Sung-Rock; Collett, Timothy S.; Kumar, Pushpendra; Dallimore, Scott

    2008-01-01

    Gas hydrate is a solid, naturally occurring substance consisting predominantly of methane gas and water. Recent scientific drilling programs in Japan, Canada, the United States, Korea and India have demonstrated that gas hydrate occurs broadly and in a variety of forms in shallow sediments of the outer continental shelves and in Arctic regions. Field, laboratory and numerical modelling studies conducted to date indicate that gas can be extracted from gas hydrates with existing production technologies, particularly for those deposits in which the gas hydrate exists as pore-filling grains at high saturation in sand-rich reservoirs. A series of regional resource assessments indicate that substantial volumes of gas hydrate likely exist in sand-rich deposits. Recent field programs in Japan, Canada and in the United States have demonstrated the technical viability of methane extraction from gas-hydrate-bearing sand reservoirs and have investigated a range of potential production scenarios. At present, basic reservoir depressurisation shows the greatest promise and can be conducted using primarily standard industry equipment and procedures. Depressurisation is expected to be the foundation of future production systems; additional processes, such as thermal stimulation, mechanical stimulation and chemical injection, will likely also be integrated as dictated by local geological and other conditions. An innovative carbon dioxide and methane swapping technology is also being studied as a method to produce gas from select gas hydrate deposits. In addition, substantial additional volumes of gas hydrate have been found in dense arrays of grain-displacing veins and nodules in fine-grained, clay-dominated sediments; however, to date, no field tests, and very limited numerical modelling, have been conducted with regard to the production potential of such accumulations. Work remains to further refine: (1) the marine resource volumes within potential accumulations that can be

  20. The entropies of adsorbed molecules.

    PubMed

    Campbell, Charles T; Sellers, Jason R V

    2012-10-31

    Adsorbed molecules are involved in many reactions on solid surface that are of great technological importance. As such, there has been tremendous effort worldwide to learn how to predict reaction rates and equilibrium constants for reactions involving adsorbed molecules. Theoretical calculation of both the rate and equilibrium constants for such reactions requires knowing the entropy and enthalpy of the adsorbed molecule. While much effort has been devoted to measuring and calculating the enthalpies of well-defined adsorbates, few measurements of the entropies of adsorbates have been reported. We present here a new way to determine the standard entropies of adsorbed molecules (S(ad)(0)) on single crystal surfaces from temperature programmed desorption data, prove its accuracy by comparison to entropies measured by equilibrium methods, and apply it to published data to extract new entropies. Most importantly, when combined with reported entropies, we find that at high coverage, they linearly track the entropy of the gas-phase molecule at the same temperature (T), such that S(ad)(0)(T) = 0.70 S(gas)(0)(T) - 3.3R (R = the gas constant), with a standard deviation of only 2R over a range of 50R. These entropies, which are ~2/3 of the gas, are huge compared to most theoretical predictions. This result can be extended to reliably predict prefactors in the Arrhenius rate constant for surface reactions involving such species, as proven here for desorption. PMID:23033909

  1. Atomistic simulations of methane interactions with an atmospheric moisture.

    PubMed

    Galashev, Alexander Y

    2013-09-28

    Methane is an extremely effective absorber of radiation, i.e., it is a relatively potent greenhouse gas, and the increased concentration of methane in the atmosphere must influence earth's radiation balance. The adsorption of one to six methane molecules by water clusters is studied by the method of molecular dynamics under near-atmospheric conditions. The capture of methane molecules by water clusters produces an increase in the integrated intensity of IR absorbance and the reflection coefficient. The Raman spectrum of the system is considerably depleted due to the addition of methane molecules to the disperse water system. The observed emission power of a dispersed aqueous system with adsorbed methane molecules has appreciably increased relative to the analogous characteristics of the pure water cluster system. The Voronoi polyhedra and simplified ones constructed within the framework of molecular-dynamic model of clusters are used for the analysis of the structure changes occurring with increasing the number of adsorbed CH4 molecules. PMID:24089763

  2. Competitive adsorption, displacement, and transport of organic matter on iron oxide: II. Displacement and transport

    SciTech Connect

    Gu, B; Mehlhorn, T.L.; Liang, Liyuan

    1996-08-01

    The competitive interactions between organic matter compounds and mineral surfaces are poorly understood, yet these interactions may play a significant role in the stability and co-transport of mineral colloids and/or environmental contaminants. In this study, the processes of competitive adsorption, displacement, and transport of Suwannee River natural organic matter (SR-NOM) are investigated with several model organic compounds in packed beds of iron oxide-coated quartz columns. Results demonstrated that strongly-binding organic compounds are competitively adsorbed and displace those weakly-bound organic compounds along the flow path. Among the four organic compounds studied, polyacrylic acid (PAA) appeared to be the most competitive, whereas SR-NOM was more competitive than phthalic and salicylic acids. A diffuse adsorption and sharp desorption front (giving an appearance of irreversible adsorption) of the SR-NOM breakthrough curves are explained as being a result of the competitive time-dependent adsorption and displacement processes between different organic components within the SR-NOM. The stability and transport of iron oxide colloids varied as one organic component competitively displaces another. Relatively large quantities of iron oxide colloids are transported when the more strongly-binding PAA competitively displaces the weakly-binding SR-NOM or when SR-NOM competitively displaces phthalic and salicylic acids. Results of this study suggest that the chemical composition and hence the functional behavior of NOM (e.g., in stabilizing mineral colloids and in complexing contaminants) can change along its flow path as a result of the dynamic competitive interactions between heterogeneous NOM subcomponents. Further studies are needed to better define and quantify these NOM components as well as their roles in contaminant partitioning and transport. 37 refs., 10 figs.

  3. Rotary adsorbers for continuous bulk separations

    DOEpatents

    Baker, Frederick S.

    2011-11-08

    A rotary adsorber for continuous bulk separations is disclosed. The rotary adsorber includes an adsorption zone in fluid communication with an influent adsorption fluid stream, and a desorption zone in fluid communication with a desorption fluid stream. The fluid streams may be gas streams or liquid streams. The rotary adsorber includes one or more adsorption blocks including adsorbent structure(s). The adsorbent structure adsorbs the target species that is to be separated from the influent fluid stream. The apparatus includes a rotary wheel for moving each adsorption block through the adsorption zone and the desorption zone. A desorption circuit passes an electrical current through the adsorbent structure in the desorption zone to desorb the species from the adsorbent structure. The adsorbent structure may include porous activated carbon fibers aligned with their longitudinal axis essentially parallel to the flow direction of the desorption fluid stream. The adsorbent structure may be an inherently electrically-conductive honeycomb structure.

  4. Displaced patella fractures.

    PubMed

    Della Rocca, Gregory J

    2013-10-01

    Displaced patella fractures often result in disruption of the extensor mechanism of the knee. An intact extensor mechanism is a requirement for unassisted gait. Therefore, operative treatment of the displaced patella fracture is generally recommended. The evaluation of the patella fracture patient includes examination of extensor mechanism integrity. Operative management of patella fractures normally includes open reduction with internal fixation, although partial patellectomy is occasionally performed, with advancement of quadriceps tendon or patellar ligament to the fracture bed. Open reduction with internal fixation has historically been performed utilizing anterior tension band wiring, although comminution of the fracture occasionally makes this fixation construct inadequate. Supplementation or replacement of the tension band wire construct with interfragmentary screws, cerclage wire or suture, and/or plate-and-screw constructs may add to the stability of the fixation construct. Arthrosis of the patellofemoral joint is very common after healing of patella fractures, and substantial functional deficits may persist long after fracture healing has occurred.

  5. Tunable beam displacer

    SciTech Connect

    Salazar-Serrano, Luis José; Valencia, Alejandra; Torres, Juan P.

    2015-03-15

    We report the implementation of a tunable beam displacer, composed of a polarizing beam splitter (PBS) and two mirrors, that divides an initially polarized beam into two parallel beams whose separation can be continuously tuned. The two output beams are linearly polarized with either vertical or horizontal polarization and no optical path difference is introduced between them. The wavelength dependence of the device as well as the maximum separation between the beams achievable is limited mainly by the PBS characteristics.

  6. Methane Plumes on Mars

    NASA Video Gallery

    Spectrometer instruments attached to several telescopes detect plumes of methane emitted from Mars during its summer and spring seasons. High levels of methane are indicated by warmer colors. The m...

  7. Up with methane

    SciTech Connect

    Barlaz, M.A.; Milke, M.W.; Ham, R.K.

    1986-12-01

    Methane production from municipal refuse represents a rapidly developing source of energy which remains underutilized. Part of the problem is the small amount of methane which is typically collected relative to the refuse's methane generation potential. This study was undertaken to define the parameters which affect the onset of methane production and methane yields in sanitary landfills. Ultimately, we need to develop refuse disposal methods which enhance its methane production potential. Included in the study were tests of how introduction of old refuse, use of sterile cover soil, addition of acetate to refuse, and use of leachate, recycling and neutralization affect methane generation. A more thorough understanding of how the microbes present in refuse react to different variables is the first step in the development of techniques for stimulating methane production in sanitary landfills.

  8. Extra adsorption and adsorbate superlattice formation in metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Sung Cho, Hae; Deng, Hexiang; Miyasaka, Keiichi; Dong, Zhiyue; Cho, Minhyung; Neimark, Alexander V.; Ku Kang, Jeung; Yaghi, Omar M.; Terasaki, Osamu

    2015-11-01

    Metal-organic frameworks (MOFs) have a high internal surface area and widely tunable composition, which make them useful for applications involving adsorption, such as hydrogen, methane or carbon dioxide storage. The selectivity and uptake capacity of the adsorption process are determined by interactions involving the adsorbates and their porous host materials. But, although the interactions of adsorbate molecules with the internal MOF surface and also amongst themselves within individual pores have been extensively studied, adsorbate-adsorbate interactions across pore walls have not been explored. Here we show that local strain in the MOF, induced by pore filling, can give rise to collective and long-range adsorbate-adsorbate interactions and the formation of adsorbate superlattices that extend beyond an original MOF unit cell. Specifically, we use in situ small-angle X-ray scattering to track and map the distribution and ordering of adsorbate molecules in five members of the mesoporous MOF-74 series along entire adsorption-desorption isotherms. We find in all cases that the capillary condensation that fills the pores gives rise to the formation of ‘extra adsorption domains’—that is, domains spanning several neighbouring pores, which have a higher adsorbate density than non-domain pores. In the case of one MOF, IRMOF-74-V-hex, these domains form a superlattice structure that is difficult to reconcile with the prevailing view of pore-filling as a stochastic process. The visualization of the adsorption process provided by our data, with clear evidence for initial adsorbate aggregation in distinct domains and ordering before an even distribution is finally reached, should help to improve our understanding of this process and may thereby improve our ability to exploit it practically.

  9. Extra adsorption and adsorbate superlattice formation in metal-organic frameworks.

    PubMed

    Sung Cho, Hae; Deng, Hexiang; Miyasaka, Keiichi; Dong, Zhiyue; Cho, Minhyung; Neimark, Alexander V; Ku Kang, Jeung; Yaghi, Omar M; Terasaki, Osamu

    2015-11-26

    Metal-organic frameworks (MOFs) have a high internal surface area and widely tunable composition, which make them useful for applications involving adsorption, such as hydrogen, methane or carbon dioxide storage. The selectivity and uptake capacity of the adsorption process are determined by interactions involving the adsorbates and their porous host materials. But, although the interactions of adsorbate molecules with the internal MOF surface and also amongst themselves within individual pores have been extensively studied, adsorbate-adsorbate interactions across pore walls have not been explored. Here we show that local strain in the MOF, induced by pore filling, can give rise to collective and long-range adsorbate-adsorbate interactions and the formation of adsorbate superlattices that extend beyond an original MOF unit cell. Specifically, we use in situ small-angle X-ray scattering to track and map the distribution and ordering of adsorbate molecules in five members of the mesoporous MOF-74 series along entire adsorption-desorption isotherms. We find in all cases that the capillary condensation that fills the pores gives rise to the formation of 'extra adsorption domains'-that is, domains spanning several neighbouring pores, which have a higher adsorbate density than non-domain pores. In the case of one MOF, IRMOF-74-V-hex, these domains form a superlattice structure that is difficult to reconcile with the prevailing view of pore-filling as a stochastic process. The visualization of the adsorption process provided by our data, with clear evidence for initial adsorbate aggregation in distinct domains and ordering before an even distribution is finally reached, should help to improve our understanding of this process and may thereby improve our ability to exploit it practically. PMID:26550825

  10. Heat pipe methanator

    DOEpatents

    Ranken, William A.; Kemme, Joseph E.

    1976-07-27

    A heat pipe methanator for converting coal gas to methane. Gravity return heat pipes are employed to remove the heat of reaction from the methanation promoting catalyst, transmitting a portion of this heat to an incoming gas pre-heat section and delivering the remainder to a steam generating heat exchanger.

  11. Nanocapsule for Safe and Effective Methane Storage

    PubMed Central

    2009-01-01

    A nanocapsule for safe and effective methane storage is investigated by the method of molecular dynamics. The mass content of methane in the nanocapsule reaches the value of 14.5 mass%. The nanocapsule consists of two parts: a locking chamber and a storage area. The locking chamber is the nanotube (10.10), open at one end, with a K@C601+endohedral complex inside it. The storage area is a nanotube (20.20). The locking chamber and the storage area are joined with each other and form T-junction. The locking chamber is opened at the methane filling and the discharge stages, and it is closed at the storage stage. Thanks to the locking chamber, methane molecules are stored in the nanocapsules under normal external conditions. Opening and closing of the locking chamber are carried out by the K@C601+endohedral complex displacement, which is done by the electric field action. The specific structure of the nanocapsule allows two aims to be reached: a high methane mass content and significant level of safety. PMID:20628460

  12. Synthesis of finite displacements and displacements in continental margins

    NASA Technical Reports Server (NTRS)

    Speed, R. C.; Elison, M. W.; Heck, F. R.; Russo, R. M.

    1988-01-01

    The scope of the project is the analysis of displacement-rate fields in the transitional regions between cratonal and oceanic lithospheres over Phanerozoic time (last 700 ma). Associated goals are an improved understanding of range of widths of major displacement zones; the partition of displacement gradients and rotations with position and depth in such zones; the temporal characteristics of such zones-the steadiness, episodicity, and duration of uniform versus nonunifrom fields; and the mechanisms and controls of the establishment and kinematics of displacement zones. The objective is to provide a context of time-averaged kinematics of displacement zones. The initial phase is divided topically among the methodology of measurement and reduction of displacements in the lithosphere and the preliminary analysis from geologic and other data of actual displacement histories from the Cordillera, Appalachians, and southern North America.

  13. Adapting to variable prismatic displacement

    NASA Technical Reports Server (NTRS)

    Welch, Robert B.; Cohen, Malcolm M.

    1989-01-01

    In each of two studies, subjects were exposed to a continuously changing prismatic displacement with a mean value of 19 prism diopters (variable displacement) and to a fixed 19-diopter displacement (fixed displacement). In Experiment 1, significant adaptation (post-pre shifts in hand-eye coordination) was found for fixed, but not for variable, displacement. Experiment 2 demonstrated that adaptation was obtained for variable displacement, but it was very fragile and is lost if the measures of adaptation are preceded by even a very brief exposure of the hand to normal or near-normal vision. Contrary to the results of some previous studies, an increase in within-S dispersion was not found of target pointing responses as a result of exposure to variable displacement.

  14. Methane photochemistry and methane production on Neptune

    NASA Astrophysics Data System (ADS)

    Romani, P. N.; Atreya, S. K.

    1988-06-01

    The Neptune stratosphere's methane photochemistry is presently studied by means of a numerical model in which the observed mixing ratio of methane prompts photolysis near the CH4 homopause. Haze generation by methane photochemistry has its basis in the formation of hydrocarbon ices and polyacetylenes; the hazes can furnish the requisite aerosol haze at the appropriate pressure levels required by observations of Neptune in the visible and near-IR. Comparisons of model predictions with Uranus data indicate a lower ratio of polyacetylene production to hydrocarbon ice, as well as a lower likelihood of UV postprocessing of the acetylene ice to polymers on Neptune, compared to Uranus.

  15. Methane photochemistry and methane production on Neptune

    NASA Technical Reports Server (NTRS)

    Romani, P. N.; Atreya, S. K.

    1988-01-01

    The Neptune stratosphere's methane photochemistry is presently studied by means of a numerical model in which the observed mixing ratio of methane prompts photolysis near the CH4 homopause. Haze generation by methane photochemistry has its basis in the formation of hydrocarbon ices and polyacetylenes; the hazes can furnish the requisite aerosol haze at the appropriate pressure levels required by observations of Neptune in the visible and near-IR. Comparisons of model predictions with Uranus data indicate a lower ratio of polyacetylene production to hydrocarbon ice, as well as a lower likelihood of UV postprocessing of the acetylene ice to polymers on Neptune, compared to Uranus.

  16. Methane photochemistry and methane production on Neptune

    SciTech Connect

    Romani, P.N.; Atreya, S.K.

    1988-06-01

    The Neptune stratosphere's methane photochemistry is presently studied by means of a numerical model in which the observed mixing ratio of methane prompts photolysis near the CH4 homopause. Haze generation by methane photochemistry has its basis in the formation of hydrocarbon ices and polyacetylenes; the hazes can furnish the requisite aerosol haze at the appropriate pressure levels required by observations of Neptune in the visible and near-IR. Comparisons of model predictions with Uranus data indicate a lower ratio of polyacetylene production to hydrocarbon ice, as well as a lower likelihood of UV postprocessing of the acetylene ice to polymers on Neptune, compared to Uranus. 65 references.

  17. Hypotheses for Near-Surface Exchange of Methane on Mars

    NASA Astrophysics Data System (ADS)

    Hu, Renyu; Bloom, A. Anthony; Gao, Peter; Miller, Charles E.; Yung, Yuk L.

    2016-07-01

    The Curiosity rover recently detected a background of 0.7 ppb and spikes of 7 ppb of methane on Mars. This in situ measurement reorients our understanding of the martian environment and its potential for life, as the current theories do not entail any geological source or sink of methane that varies sub-annually. In particular, the 10-fold elevation during the southern winter indicates episodic sources of methane that are yet to be discovered. Here we suggest a near-surface reservoir could explain this variability. Using the temperature and humidity measurements from the rover, we find that perchlorate salts in the regolith deliquesce to form liquid solutions, and deliquescence progresses to deeper subsurface in the season of the methane spikes. We therefore formulate the following three testable hypotheses. The first scenario is that the regolith in Gale Crater adsorbs methane when dry and releases this methane to the atmosphere upon deliquescence. The adsorption energy needs to be 36 kJ mol-1 to explain the magnitude of the methane spikes, higher than existing laboratory measurements. The second scenario is that microorganisms convert organic matter in the soil to methane when they are in liquid solutions. This scenario does not require regolith adsorption but entails extant life on Mars. The third scenario is that deep subsurface aquifers produce the bursts of methane. Continued in situ measurements of methane and water, as well as laboratory studies of adsorption and deliquescence, will test these hypotheses and inform the existence of the near-surface reservoir and its exchange with the atmosphere.

  18. Research on the theory and application of adsorbed natural gas used in new energy vehicles: A review

    NASA Astrophysics Data System (ADS)

    Nie, Zhengwei; Lin, Yuyi; Jin, Xiaoyi

    2016-09-01

    Natural gas, whose primary constituent is methane, has been considered a convincing alternative for the growth of the energy supply worldwide. Adsorbed natural gas (ANG), the most promising methane storage method, has been an active field of study in the past two decades. ANG constitutes a safe and low-cost way to store methane for natural gas vehicles at an acceptable energy density while working at substantially low pressures (3.5-4.0 MPa), allowing for conformable store tank. This work serves to review the state-of-the-art development reported in the scientific literature on adsorbents, adsorption theories, ANG conformable tanks, and related technologies on ANG vehicles. Patent literature has also been searched and discussed. The review aims at illustrating both achievements and problems of the ANG technologies- based vehicles, as well as forecasting the development trends and critical issues to be resolved of these technologies.

  19. Research on the theory and application of adsorbed natural gas used in new energy vehicles: A review

    NASA Astrophysics Data System (ADS)

    Nie, Zhengwei; Lin, Yuyi; Jin, Xiaoyi

    2016-05-01

    Natural gas, whose primary constituent is methane, has been considered a convincing alternative for the growth of the energy supply worldwide. Adsorbed natural gas (ANG), the most promising methane storage method, has been an active field of study in the past two decades. ANG constitutes a safe and low-cost way to store methane for natural gas vehicles at an acceptable energy density while working at substantially low pressures (3.5-4.0 MPa), allowing for conformable store tank. This work serves to review the state-of-the-art development reported in the scientific literature on adsorbents, adsorption theories, ANG conformable tanks, and related technologies on ANG vehicles. Patent literature has also been searched and discussed. The review aims at illustrating both achievements and problems of the ANG technologies- based vehicles, as well as forecasting the development trends and critical issues to be resolved of these technologies.

  20. Strategies for displacing oil

    NASA Astrophysics Data System (ADS)

    Rao, Vikram; Gupta, Raghubir

    2015-03-01

    Oil currently holds a monopoly on transportation fuels. Until recently biofuels were seen as the means to break this stranglehold. They will still have a part to play, but the lead role has been handed to natural gas, almost solely due to the increased availability of shale gas. The spread between oil and gas prices, unprecedented in its scale and duration, will cause a secular shift away from oil as a raw material. In the transport fuel sector, natural gas will gain traction first in the displacement of diesel fuel. Substantial innovation is occurring in the methods of producing liquid fuel from shale gas at the well site, in particular in the development of small scale distributed processes. In some cases, the financing of such small-scale plants may require new business models.

  1. Variable displacement blower

    DOEpatents

    Bookout, Charles C.; Stotts, Robert E.; Waring, Douglass R.; Folsom, Lawrence R.

    1986-01-01

    A blower having a stationary casing for rotatably supporting a rotor assembly having a series of open ended chambers arranged to close against the surrounding walls of the casing. Pistons are slidably mounted within each chamber with the center of rotation of the pistons being offset in regard to the center of rotation of the rotor assembly whereby the pistons reciprocate in the chambers as the rotor assembly turns. As inlet port communicates with the rotor assembly to deliver a working substance into the chamber as the pistons approach a top dead center position in the chamber while an outlet port also communicates with the rotor to exhaust the working substance as the pistons approach a bottom dead center position. The displacement of the blower is varied by adjusting the amount of eccentricity between the center of rotation of the pistons and the center of rotation of the rotor assembly.

  2. Methane emission from sewers.

    PubMed

    Liu, Yiwen; Ni, Bing-Jie; Sharma, Keshab R; Yuan, Zhiguo

    2015-08-15

    Recent studies have shown that sewer systems produce and emit a significant amount of methane. Methanogens produce methane under anaerobic conditions in sewer biofilms and sediments, and the stratification of methanogens and sulfate-reducing bacteria may explain the simultaneous production of methane and sulfide in sewers. No significant methane sinks or methanotrophic activities have been identified in sewers to date. Therefore, most of the methane would be emitted at the interface between sewage and atmosphere in gravity sewers, pumping stations, and inlets of wastewater treatment plants, although oxidation of methane in the aeration basin of a wastewater treatment plant has been reported recently. Online measurements have also revealed highly dynamic temporal and spatial variations in methane production caused by factors such as hydraulic retention time, area-to-volume ratio, temperature, and concentration of organic matter in sewage. Both mechanistic and empirical models have been proposed to predict methane production in sewers. Due to the sensitivity of methanogens to environmental conditions, most of the chemicals effective in controlling sulfide in sewers also suppress or diminish methane production. In this paper, we review the recent studies on methane emission from sewers, including the production mechanisms, quantification, modeling, and mitigation. PMID:25889543

  3. Methane emission from sewers.

    PubMed

    Liu, Yiwen; Ni, Bing-Jie; Sharma, Keshab R; Yuan, Zhiguo

    2015-08-15

    Recent studies have shown that sewer systems produce and emit a significant amount of methane. Methanogens produce methane under anaerobic conditions in sewer biofilms and sediments, and the stratification of methanogens and sulfate-reducing bacteria may explain the simultaneous production of methane and sulfide in sewers. No significant methane sinks or methanotrophic activities have been identified in sewers to date. Therefore, most of the methane would be emitted at the interface between sewage and atmosphere in gravity sewers, pumping stations, and inlets of wastewater treatment plants, although oxidation of methane in the aeration basin of a wastewater treatment plant has been reported recently. Online measurements have also revealed highly dynamic temporal and spatial variations in methane production caused by factors such as hydraulic retention time, area-to-volume ratio, temperature, and concentration of organic matter in sewage. Both mechanistic and empirical models have been proposed to predict methane production in sewers. Due to the sensitivity of methanogens to environmental conditions, most of the chemicals effective in controlling sulfide in sewers also suppress or diminish methane production. In this paper, we review the recent studies on methane emission from sewers, including the production mechanisms, quantification, modeling, and mitigation.

  4. Displacement parameter inversion for a novel electromagnetic underground displacement sensor.

    PubMed

    Shentu, Nanying; Li, Qing; Li, Xiong; Tong, Renyuan; Shentu, Nankai; Jiang, Guoqing; Qiu, Guohua

    2014-05-22

    Underground displacement monitoring is an effective method to explore deep into rock and soil masses for execution of subsurface displacement measurements. It is not only an important means of geological hazards prediction and forecasting, but also a forefront, hot and sophisticated subject in current geological disaster monitoring. In previous research, the authors had designed a novel electromagnetic underground horizontal displacement sensor (called the H-type sensor) by combining basic electromagnetic induction principles with modern sensing techniques and established a mutual voltage measurement theoretical model called the Equation-based Equivalent Loop Approach (EELA). Based on that work, this paper presents an underground displacement inversion approach named "EELA forward modeling-approximate inversion method". Combining the EELA forward simulation approach with the approximate optimization inversion theory, it can deduce the underground horizontal displacement through parameter inversion of the H-type sensor. Comprehensive and comparative studies have been conducted between the experimentally measured and theoretically inversed values of horizontal displacement under counterpart conditions. The results show when the measured horizontal displacements are in the 0-100 mm range, the horizontal displacement inversion discrepancy is generally tested to be less than 3 mm under varied tilt angles and initial axial distances conditions, which indicates that our proposed parameter inversion method can predict underground horizontal displacement measurements effectively and robustly for the H-type sensor and the technique is applicable for practical geo-engineering applications.

  5. Displacement parameter inversion for a novel electromagnetic underground displacement sensor.

    PubMed

    Shentu, Nanying; Li, Qing; Li, Xiong; Tong, Renyuan; Shentu, Nankai; Jiang, Guoqing; Qiu, Guohua

    2014-01-01

    Underground displacement monitoring is an effective method to explore deep into rock and soil masses for execution of subsurface displacement measurements. It is not only an important means of geological hazards prediction and forecasting, but also a forefront, hot and sophisticated subject in current geological disaster monitoring. In previous research, the authors had designed a novel electromagnetic underground horizontal displacement sensor (called the H-type sensor) by combining basic electromagnetic induction principles with modern sensing techniques and established a mutual voltage measurement theoretical model called the Equation-based Equivalent Loop Approach (EELA). Based on that work, this paper presents an underground displacement inversion approach named "EELA forward modeling-approximate inversion method". Combining the EELA forward simulation approach with the approximate optimization inversion theory, it can deduce the underground horizontal displacement through parameter inversion of the H-type sensor. Comprehensive and comparative studies have been conducted between the experimentally measured and theoretically inversed values of horizontal displacement under counterpart conditions. The results show when the measured horizontal displacements are in the 0-100 mm range, the horizontal displacement inversion discrepancy is generally tested to be less than 3 mm under varied tilt angles and initial axial distances conditions, which indicates that our proposed parameter inversion method can predict underground horizontal displacement measurements effectively and robustly for the H-type sensor and the technique is applicable for practical geo-engineering applications. PMID:24858960

  6. Displacement Parameter Inversion for a Novel Electromagnetic Underground Displacement Sensor

    PubMed Central

    Shentu, Nanying; Li, Qing; Li, Xiong; Tong, Renyuan; Shentu, Nankai; Jiang, Guoqing; Qiu, Guohua

    2014-01-01

    Underground displacement monitoring is an effective method to explore deep into rock and soil masses for execution of subsurface displacement measurements. It is not only an important means of geological hazards prediction and forecasting, but also a forefront, hot and sophisticated subject in current geological disaster monitoring. In previous research, the authors had designed a novel electromagnetic underground horizontal displacement sensor (called the H-type sensor) by combining basic electromagnetic induction principles with modern sensing techniques and established a mutual voltage measurement theoretical model called the Equation-based Equivalent Loop Approach (EELA). Based on that work, this paper presents an underground displacement inversion approach named “EELA forward modeling-approximate inversion method”. Combining the EELA forward simulation approach with the approximate optimization inversion theory, it can deduce the underground horizontal displacement through parameter inversion of the H-type sensor. Comprehensive and comparative studies have been conducted between the experimentally measured and theoretically inversed values of horizontal displacement under counterpart conditions. The results show when the measured horizontal displacements are in the 0–100 mm range, the horizontal displacement inversion discrepancy is generally tested to be less than 3 mm under varied tilt angles and initial axial distances conditions, which indicates that our proposed parameter inversion method can predict underground horizontal displacement measurements effectively and robustly for the H-type sensor and the technique is applicable for practical geo-engineering applications. PMID:24858960

  7. Supercritical fluid regeneration of adsorbents

    NASA Astrophysics Data System (ADS)

    Defilippi, R. P.; Robey, R. J.

    1983-05-01

    The results of a program to perform studies supercritical (fluid) carbon dioxide (SCF CO2) regeneration of adsorbents, using samples of industrial wastewaters from manufacturing pesticides and synthetic solution, and to estimate the economics of the specific wastewater treatment regenerations, based on test data are given. Processing costs for regenerating granular activated carbon GAC) for treating industrial wastewaters depend on stream properties and regeneration throughput.

  8. Measuring vulnerability to disaster displacement

    NASA Astrophysics Data System (ADS)

    Brink, Susan A.; Khazai, Bijan; Power, Christopher; Wenzel, Friedemann

    2015-04-01

    Large scale disasters can cause devastating impacts in terms of population displacement. Between 2008 and 2013, on average 27 million people were displaced annually by disasters (Yonetani 2014). After large events such as hurricane Katrina or the Port-au-Prince earthquake, images of inadequate public shelter and concerns about large scale and often inequitable migration have been broadcast around the world. Population displacement can often be one of the most devastating and visible impacts of a natural disaster. Despite the importance of population displacement in disaster events, measures to understand the socio-economic vulnerability of a community often use broad metrics to estimate the total socio-economic risk of an event rather than focusing on the specific impacts that a community faces in a disaster. Population displacement is complex and multi-causal with the physical impact of a disaster interacting with vulnerability arising from the response, environmental issues (e.g., weather), cultural concerns (e.g., expectations of adequate shelter), and many individual factors (e.g., mobility, risk perception). In addition to the complexity of the causes, population displacement is difficult to measure because of the wide variety of different terms and definitions and its multi-dimensional nature. When we speak of severe population displacement, we may refer to a large number of displaced people, an extended length of displacement or associated difficulties such as poor shelter quality, risk of violence and crime in shelter communities, discrimination in aid, a lack of access to employment or other difficulties that can be associated with large scale population displacement. We have completed a thorough review of the literature on disaster population displacement. Research has been conducted on historic events to understand the types of negative impacts associated with population displacement and also the vulnerability of different groups to these impacts. We

  9. Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption

    SciTech Connect

    Anna Lee Tonkovich

    2004-07-01

    The purpose of this project is to design and demonstrate an approach to upgrade low-BTU methane streams from coal mines to pipeline-quality natural gas. The objective of Phase I of the project was to assess the technical feasibility and cost of upgrading low-BTU methane streams using ultra-fast thermal swing adsorption (TSA) using Velocys modular microchannel process technology. The objective of Phase II is to demonstrate the process at the bench scale. The project is on schedule and on budget. A technical and economic feasibility assessment was completed in Task 3. The proposed Velocys technology appears feasible for the methane upgrading market. Evaluated categories include adsorbent selection, rapid-cycle valve selection, microchannel manufacturability assessment, and system design and cost. The selected adsorbent, granular microporous carbon from either Barnaby-Sutcliffe or Calgon, experimentally demonstrated sufficient methane capacity under differential temperature at 100 pounds per square inch gauge. Several valve options were identified, including candidates that can operate millions of cycles between refurbishment. The microchannel adsorber and desorber designs were made using internal Velocys manufacturability standards, and the associated costs are acceptable as included with the complete nitrogen rejection unit (NRU) cost projection. A system design and cost estimate was completed for the NRU section of the methane upgrading system. As integrated into the complete system, the cost is in line with the market requirement. The system has six main unit operations: feed compressor, dehydration unit, nitrogen rejection unit, deoxygenator, carbon dioxide scrubber, and a sales compressor. The NRU is the focus of the development program, and a bench-scale demonstration will be initiated in the next fiscal year. The Velocys NRU system targets producing methane with greater than 96% purity and at least 90% recovery for final commercial operation. A preliminary

  10. Methane-Powered Vehicles

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Liquid methane is beginning to become an energy alternative to expensive oil as a power source for automotive vehicles. Methane is the principal component of natural gas, costs less than half as much as gasoline, and its emissions are a lot cleaner than from gasoline or diesel engines. Beech Aircraft Corporation's Boulder Division has designed and is producing a system for converting cars and trucks to liquid methane operation. Liquid methane (LM) is a cryogenic fuel which must be stored at a temperature of 260 degrees below zero Fahrenheit. The LM system includes an 18 gallon fuel tank in the trunk and simple "under the hood" carburetor conversion equipment. Optional twin-fuel system allows operator to use either LM or gasoline fuel. Boulder Division has started deliveries for 25 vehicle conversions and is furnishing a liquid methane refueling station. Beech is providing instruction for Northwest Natural Gas, for conversion of methane to liquid state.

  11. Mars methane engine

    NASA Technical Reports Server (NTRS)

    Bui, Hung; Coletta, Chris; Debois, Alain

    1994-01-01

    The feasibility of an internal combustion engine operating on a mixture of methane, carbon dioxide, and oxygen has been verified by previous design groups for the Mars Methane Engine Project. Preliminary stoichiometric calculations examined the theoretical fuel-air ratios needed for the combustion of methane. Installation of a computer data acquisition system along with various ancillary components will enable the performance of the engine, running on the described methane mixture, to be optimized with respect to minimizing excess fuel. Theoretical calculations for stoichiometric combustion of methane-oxygen-carbon dioxide mixtures yielded a ratio of 1:2:4.79 for a methane-oxygen-carbon dioxide mixture. Empirical data shows the values to be closer to 1:2.33:3.69 for optimum operation.

  12. Detecting Methane Leaks

    NASA Technical Reports Server (NTRS)

    Grant, W. B.; Hinkley, E. D.

    1984-01-01

    Remote sensor uses laser radiation backscattered from natural targets. He/Ne Laser System for remote scanning of Methane leaks employs topographic target to scatter light to receiver near laser transmitter. Apparatus powered by 1.5kW generator transported to field sites and pointed at suspected methane leaks. Used for remote detection of natural-gas leaks and locating methane emissions in landfill sites.

  13. Methane emissions from cattle.

    PubMed

    Johnson, K A; Johnson, D E

    1995-08-01

    Increasing atmospheric concentrations of methane have led scientists to examine its sources of origin. Ruminant livestock can produce 250 to 500 L of methane per day. This level of production results in estimates of the contribution by cattle to global warming that may occur in the next 50 to 100 yr to be a little less than 2%. Many factors influence methane emissions from cattle and include the following: level of feed intake, type of carbohydrate in the diet, feed processing, addition of lipids or ionophores to the diet, and alterations in the ruminal microflora. Manipulation of these factors can reduce methane emissions from cattle. Many techniques exist to quantify methane emissions from individual or groups of animals. Enclosure techniques are precise but require trained animals and may limit animal movement. Isotopic and nonisotopic tracer techniques may also be used effectively. Prediction equations based on fermentation balance or feed characteristics have been used to estimate methane production. These equations are useful, but the assumptions and conditions that must be met for each equation limit their ability to accurately predict methane production. Methane production from groups of animals can be measured by mass balance, micrometeorological, or tracer methods. These techniques can measure methane emissions from animals in either indoor or outdoor enclosures. Use of these techniques and knowledge of the factors that impact methane production can result in the development of mitigation strategies to reduce methane losses by cattle. Implementation of these strategies should result in enhanced animal productivity and decreased contributions by cattle to the atmospheric methane budget.

  14. Method And Apparatus For Regenerating Nox Adsorbers

    DOEpatents

    Driscoll, J. Joshua; Endicott, Dennis L.; Faulkner, Stephen A.; Verkiel, Maarten

    2006-03-28

    Methods and apparatuses for regenerating a NOx adsorber coupled with an exhaust of an engine. An actuator drives a throttle valve to a first position when regeneration of the NOx adsorber is desired. The first position is a position that causes the regeneration of the NOx adsorber. An actuator drives the throttle valve to a second position while regeneration of the NOx adsorber is still desired. The second position being a position that is more open than the first position and operable to regenerate a NOx adsorber.

  15. Seafloor methane: Atlantic bubble bath

    NASA Astrophysics Data System (ADS)

    Kessler, John

    2014-09-01

    The release of large quantities of methane from ocean sediments might affect global climate change. The discovery of expansive methane seeps along the US Atlantic margin provides an ideal test bed for such a marine methane-climate connection.

  16. The future of methane

    SciTech Connect

    Howell, D.G.

    1995-12-31

    Natural gas, mainly methane, produces lower CO{sub 2}, CO, NO{sub x}, SO{sub 2} and particulate emissions than either oil or coal; thus further substitutions of methane for these fuels could help mitigate air pollution. Methane is, however, a potent greenhouse gas and the domestication of ruminants, cultivation of rice, mining of coal, drilling for oil, and transportation of natural gas have all contributed to a doubling of the amount of atmospheric methane since 1800. Today nearly 300,000 wells yearly produce ca. 21 trillion cubic feet of methane. Known reserves suggest about a 10 year supply at the above rates of recovery; and the potential for undiscovered resources is obscured by uncertainty involving price, new technologies, and environmental restrictions steming from the need to drill an enormous number of wells, many in ecologically sensitive areas. Until all these aspects of methane are better understood, its future role in the world`s energy mix will remain uncertain. The atomic simplicity of methane, composed of one carbon and four hydrogen atoms, may mask the complexity and importance of this, the most basic of organic molecules. Within the Earth, methane is produced through thermochemical alteration of organic materials, and by biochemical reactions mediated by metabolic processes of archaebacteria; some methane may even be primordial, a residue of planetary accretion. Methane also occurs in smaller volumes in landfills, rice paddies, termite complexes, ruminants, and even many humans. As an energy source, its full energy potential is controversial. Methane is touted by some as a viable bridge to future energy systems, fueled by the sun and uranium and carried by electricity and hydrogen.

  17. Methanation assembly using multiple reactors

    DOEpatents

    Jahnke, Fred C.; Parab, Sanjay C.

    2007-07-24

    A methanation assembly for use with a water supply and a gas supply containing gas to be methanated in which a reactor assembly has a plurality of methanation reactors each for methanating gas input to the assembly and a gas delivery and cooling assembly adapted to deliver gas from the gas supply to each of said methanation reactors and to combine water from the water supply with the output of each methanation reactor being conveyed to a next methanation reactor and carry the mixture to such next methanation reactor.

  18. Displacement, Substitution, Sublimation: A Bibliography.

    ERIC Educational Resources Information Center

    Pedrini, D. T.; Pedrini, Bonnie C.

    Sigmund Freund worked with the mechanisms of displacement, substitution, and sublimation. These mechanisms have many similarities and have been studied diagnostically and therapeutically. Displacement and substitution seem to fit in well with phobias, hysterias, somatiyations, prejudices, and scapegoating. Phobias, prejudices, and scapegoating…

  19. Displaced Homemakers Project. Leader's Guide.

    ERIC Educational Resources Information Center

    Musickant, Claire

    This handbook is designed to assist vocational technical adult education providers in developing workshops for displaced homemakers. Covered first are various aspects of planning a displaced homemakers workshop, including format, time, location, publicity and recruitment, staff and presenters, community resources, budget items, and other…

  20. Review of Molecular Simulations of Methane Storage in Metal-Organic Frameworks.

    PubMed

    Lee, Seung-Joon; Bae, Youn-Sang

    2016-05-01

    Methane storage in porous materials is one of the hot issues because it can replace dangerous high-pressure compressed natural gas (CNG) tanks in natural gas vehicles. Among the diverse adsorbents, metal-organic frameworks (MOFs) are considered to be promising due to their extremely high surface areas and low crystal densities. Molecular simulation has been considered as an important tool for finding an appropriate MOF for methane storage. We review several important roles of molecular modeling for the studies of methane adsorption in MOFs. PMID:27483748

  1. Methane drizzle on Titan.

    PubMed

    Tokano, Tetsuya; McKay, Christopher P; Neubauer, Fritz M; Atreya, Sushil K; Ferri, Francesca; Fulchignoni, Marcello; Niemann, Hasso B

    2006-07-27

    Saturn's moon Titan shows landscapes with fluvial features suggestive of hydrology based on liquid methane. Recent efforts in understanding Titan's methane hydrological cycle have focused on occasional cloud outbursts near the south pole or cloud streaks at southern mid-latitudes and the mechanisms of their formation. It is not known, however, if the clouds produce rain or if there are also non-convective clouds, as predicted by several models. Here we show that the in situ data on the methane concentration and temperature profile in Titan's troposphere point to the presence of layered optically thin stratiform clouds. The data indicate an upper methane ice cloud and a lower, barely visible, liquid methane-nitrogen cloud, with a gap in between. The lower, liquid, cloud produces drizzle that reaches the surface. These non-convective methane clouds are quasi-permanent features supported by the global atmospheric circulation, indicating that methane precipitation occurs wherever there is slow upward motion. This drizzle is a persistent component of Titan's methane hydrological cycle and, by wetting the surface on a global scale, plays an active role in the surface geology of Titan.

  2. Methane conversion process

    SciTech Connect

    Gaffney, A.M.; Jones, C.A.; Sofranko, J.A.

    1989-01-03

    This patent describes a process for the conversion of methane to higher hydrocarbons and coproduct water wherein methane is contacted at reactive conditions with a conversion catalyst comprised of a reducible metal oxide selected from the group consisting of an oxide of manganese, tin, indium, germanium, antimony, leads, bismuth, cerium, praseodymium, terbium, iron, and ruthenium. The improvement consists of: pretreating the catalyst before use in the conversion of methane to higher hydrocarbons and coproduct water with a reducing agent at 650/sup 0/C to 1200/sup 0/C for a time sufficient to improve the bulk density and attrition resistance of the catalyst and thereafter contacting the pretreated catalyst with methane at methane conversion conditions effective to form higher hydrocarbons and coproduct water.

  3. Regenerative rotary displacer Stirling engine

    SciTech Connect

    Isshiki, Naotsugu; Watanabe, Hiroichi; Raggi, L.; Isshiki, Seita; Hirata, Koichi

    1996-12-31

    A few rotary displacer Stirling engines in which the displacer has one gas pocket space at one side and rotates in a main enclosed cylinder, which is heated from one side and cooled from opposite side without any regenerator, have been studied for some time by the authors. The authors tried to improve this engine by equipping it with a regenerator, because without a regenerator, pressure oscillation and efficiency are too small. Here, several types of regenerative rotary displacer piston Stirling engines are proposed. One is the contra-rotating tandem two disc type displacer engine using axial heat conduction through side walls or by heat pipes and another is a single disc type with circulating fluid regenerator or heat pipes. Stirling engines of this new rotary displacer type are thought to attain high speed. Here, experimental results of the original rotary displacer Stirling engine without a regenerator, and one contra-rotating tandem displacer engine with side wall regenerator by axial heat conduction are reported accompanied with a discussion of the results.

  4. A novel fiber-based adsorbent technology

    SciTech Connect

    Reynolds, T.A.

    1997-10-01

    In this Phase I Small Business Innovation Research program, Chemica Technologies, Inc. is developing an economical, robust, fiber-based adsorbent technology for removal of heavy metals from contaminated water. The key innovation is the development of regenerable adsorbent fibers and adsorbent fiber cloths that have high capacity and selectivity for heavy metals and are chemically robust. The process has the potential for widespread use at DOE facilities, mining operations, and the chemical process industry.

  5. Borehole optical lateral displacement sensor

    DOEpatents

    Lewis, R.E.

    1998-10-20

    There is provided by this invention an optical displacement sensor that utilizes a reflective target connected to a surface to be monitored to reflect light from a light source such that the reflected light is received by a photoelectric transducer. The electric signal from the photoelectric transducer is then imputed into electronic circuitry to generate an electronic image of the target. The target`s image is monitored to determine the quantity and direction of any lateral displacement in the target`s image which represents lateral displacement in the surface being monitored. 4 figs.

  6. Quasiparticle excitations of adsorbates on doped graphene

    NASA Astrophysics Data System (ADS)

    Lischner, Johannes; Wickenburg, Sebastian; Wong, Dillon; Karrasch, Christoph; Wang, Yang; Lu, Jiong; Omrani, Arash A.; Brar, Victor; Tsai, Hsin-Zon; Wu, Qiong; Corsetti, Fabiano; Mostofi, Arash; Kawakami, Roland K.; Moore, Joel; Zettl, Alex; Louie, Steven G.; Crommie, Mike

    Adsorbed atoms and molecules can modify the electronic structure of graphene, but in turn it is also possible to control the properties of adsorbates via the graphene substrate. In my talk, I will discuss the electronic structure of F4-TCNQ molecules on doped graphene and present a first-principles based theory of quasiparticle excitations that captures the interplay of doping-dependent image charge interactions between substrate and adsorbate and electron-electron interaction effects on the molecule. The resulting doping-dependent quasiparticle energies will be compared to experimental scanning tunnelling spectra. Finally, I will also discuss the effects of charged adsorbates on the electronic structure of doped graphene.

  7. Structural and topographical characteristics of adsorbed WPI and monoglyceride mixed monolayers at the air-water interface.

    PubMed

    Patino, Juan M Rodríguez; Fernández, Marta Cejudo

    2004-05-25

    In this work we have analyzed the structural and topographical characteristics of mixed monolayers formed by an adsorbed whey protein isolate (WPI) and a spread monoglyceride monolayer (monopalmitin or monoolein) on the previously adsorbed protein film. Measurements of the surface pressure (pi)-area (A) isotherm were obtained at 20 degrees C and at pH 7 for protein-adsorbed films from water in a Wilhelmy-type film balance. Since the surface concentration (1/A) is actually unknown for the adsorbed monolayer, the values were derived by assuming that the A values for adsorbed and spread monolayers were equal at the collapse point of the mixed film. The pi-A isotherm deduced for adsorbed WPI monolayer in this work is practically the same as that obtained directly by spreading. For WPI-monoglyceride mixed films, the pi-A isotherms for adsorbed and spread monolayers at pi higher than the equilibrium surface pressure of WPI are practically coincident, a phenomenon which may be attributed to the protein displacement by the monoglyceride from the interface. At lower surface pressures, WPI and monoglyceride coexist at the interface and the adsorbed and spread pi-A isotherms (i.e., the monolayer structure of the mixed films) are different. Monopalmitin has a higher capacity than monoolein for the displacement of protein from the air-water interface. However, some degree of interactions exists between proteins and monoglycerides and these interactions are higher for adsorbed than for spread films. The topography of the monolayer corroborates these conclusions.

  8. Methane emission by camelids.

    PubMed

    Dittmann, Marie T; Runge, Ullrich; Lang, Richard A; Moser, Dario; Galeffi, Cordula; Kreuzer, Michael; Clauss, Marcus

    2014-01-01

    Methane emissions from ruminant livestock have been intensively studied in order to reduce contribution to the greenhouse effect. Ruminants were found to produce more enteric methane than other mammalian herbivores. As camelids share some features of their digestive anatomy and physiology with ruminants, it has been proposed that they produce similar amounts of methane per unit of body mass. This is of special relevance for countrywide greenhouse gas budgets of countries that harbor large populations of camelids like Australia. However, hardly any quantitative methane emission measurements have been performed in camelids. In order to fill this gap, we carried out respiration chamber measurements with three camelid species (Vicugna pacos, Lama glama, Camelus bactrianus; n = 16 in total), all kept on a diet consisting of food produced from alfalfa only. The camelids produced less methane expressed on the basis of body mass (0.32±0.11 L kg⁻¹ d⁻¹) when compared to literature data on domestic ruminants fed on roughage diets (0.58±0.16 L kg⁻¹ d⁻¹). However, there was no significant difference between the two suborders when methane emission was expressed on the basis of digestible neutral detergent fiber intake (92.7±33.9 L kg⁻¹ in camelids vs. 86.2±12.1 L kg⁻¹ in ruminants). This implies that the pathways of methanogenesis forming part of the microbial digestion of fiber in the foregut are similar between the groups, and that the lower methane emission of camelids can be explained by their generally lower relative food intake. Our results suggest that the methane emission of Australia's feral camels corresponds only to 1 to 2% of the methane amount produced by the countries' domestic ruminants and that calculations of greenhouse gas budgets of countries with large camelid populations based on equations developed for ruminants are generally overestimating the actual levels.

  9. Sacrificial adsorbate for surfactants utilized in chemical floods of enhanced oil recovery operations

    DOEpatents

    Johnson, J.S. Jr.; Westmoreland, C.G.

    1980-08-20

    The present invention is directed to a sacrificial or competitive adsorbate for surfactants contained in chemical flooding emulsions for enhanced oil recovery operations. The adsorbate to be utilized in the method of the present invention is a caustic effluent from the bleach stage or the weak black liquor from the digesters and pulp washers of the kraft pulping process. This effluent or weak black liquor is injected into an oil-bearing subterranean earth formation prior to or concurrent with the chemical flood emulsion and is adsorbed on the active mineral surfaces of the formation matrix so as to effectively reduce adsorption of surfactant in the chemical flood. Alternatively, the effluent or liquor can be injected into the subterranean earth formation subsequent to a chemical flood to displace the surfactant from the mineral surfaces for the recovery thereof.

  10. Sacrificial adsorbate for surfactants utilized in chemical floods of enhanced oil recovery operations

    DOEpatents

    Johnson, Jr., James S.; Westmoreland, Clyde G.

    1982-01-01

    The present invention is directed to a sacrificial or competitive adsorbate for surfactants contained in chemical flooding emulsions for enhanced oil recovery operations. The adsorbate to be utilized in the method of the present invention is a caustic effluent from the bleach stage or the weak black liquor from the digesters and pulp washers of the kraft pulping process. This effluent or weak black liquor is injected into an oil-bearing subterranean earth formation prior to or concurrent with the chemical flood emulsion and is adsorbed on the active mineral surfaces of the formation matrix so as to effectively reduce adsorption of surfactant in the chemical flood. Alternatively, the effluent or liquor can be injected into the subterranean earth formation subsequent to a chemical flood to displace the surfactant from the mineral surfaces for the recovery thereof.

  11. Polyimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Hergenrother, Paul M.

    1990-01-01

    Experiments show variety of polyimidazoles prepared by aromatic nucleophilic displacement, from reactions of bisphenol imidazoles with activated difluoro compounds. Polyimidazoles have good mechanical properties making them suitable for use as films, moldings, and adhesives.

  12. Displacement sensing system and method

    DOEpatents

    VunKannon, Jr., Robert S

    2006-08-08

    A displacement sensing system and method addresses demanding requirements for high precision sensing of displacement of a shaft, for use typically in a linear electro-dynamic machine, having low failure rates over multi-year unattended operation in hostile environments. Applications include outer space travel by spacecraft having high-temperature, sealed environments without opportunity for servicing over many years of operation. The displacement sensing system uses a three coil sensor configuration, including a reference and sense coils, to provide a pair of ratio-metric signals, which are inputted into a synchronous comparison circuit, which is synchronously processed for a resultant displacement determination. The pair of ratio-metric signals are similarly affected by environmental conditions so that the comparison circuit is able to subtract or nullify environmental conditions that would otherwise cause changes in accuracy to occur.

  13. Theoretical investigation of methane adsorption onto boron nitride and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Darvish Ganji, Masoud; Mirnejad, Amir; Najafi, Ali

    2010-08-01

    Methane adsorption onto single-wall boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs) was studied using the density functional theory within the generalized gradient approximation. The structural optimization of several bonding configurations for a CH4 molecule approaching the outer surface of the (8,0) BNNT and (8,0) CNT shows that the CH4 molecule is preferentially adsorbed onto the CNT with a binding energy of -2.84 kcal mol-1. A comparative study of nanotubes with different diameters (curvatures) reveals that the methane adsorptive capability for the exterior surface increases for wider CNTs and decreases for wider BNNTs. The introduction of defects in the BNNT significantly enhances methane adsorption. We also examined the possibility of binding a bilayer or a single layer of methane molecules and found that methane molecules preferentially adsorb as a single layer onto either BNNTs or CNTs. However, bilayer adsorption is feasible for CNTs and defective BNNTs and requires binding energies of -3.00 and -1.44 kcal mol-1 per adsorbed CH4 molecule, respectively. Our first-principles findings indicate that BNNTs might be an unsuitable material for natural gas storage.

  14. The uranium from seawater program at PNNL: Overview of marine testing, adsorbent characterization, adsorbent durability, adsorbent toxicity, and deployment studies

    DOE PAGES

    Gill, Gary A.; Kuo, Li -Jung; Janke, Christopher James; Park, Jiyeon; Jeters, Robert T.; Bonheyo, George T.; Pan, Horng -Bin; Wai, Chien; Khangaonkar, Tarang P.; Bianucci, Laura; et al

    2016-02-07

    The Pacific Northwest National Laboratory's (PNNL) Marine Science Laboratory (MSL) located along the coast of Washington State is evaluating the performance of uranium adsorption materials being developed for seawater extraction under realistic marine conditions with natural seawater. Two types of exposure systems were employed in this program: flow-through columns for testing of fixed beds of individual fibers and pellets and a recirculating water flume for testing of braided adsorbent material. Testing consists of measurements of the adsorption of uranium and other elements from seawater as a function of time, typically 42 to 56 day exposures, to determine the adsorbent capacitymore » and adsorption rate (kinetics). Analysis of uranium and other trace elements collected by the adsorbents was conducted following strong acid digestion of the adsorbent with 50% aqua regia using either Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The ORNL 38H adsorbent had a 56 day adsorption capacity of 3.30 ± 0.68 g U/ kg adsorbent (normalized to a salinity of 35 psu), a saturation adsorption capacity of 4.89 ± 0.83 g U/kg of adsorbent material (normalized to a salinity of 35 psu) and a half-saturation time of 28 10 days. The AF1 adsorbent material had a 56 day adsorption capacity of 3.9 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu), a saturation capacity of 5.4 ± 0.2 g U/kg adsorbent material (normalized to a salinity of 35 psu) and a half saturation time of 23 2 days. The ORNL amidoxime-based adsorbent materials are not specific for uranium, but also adsorb other elements from seawater. The major doubly charged cations in seawater (Ca and Mg) account for a majority of the cations adsorbed (61% by mass and 74% by molar percent). For the ORNL AF1 adsorbent material, U is the 4th most abundant element adsorbed by mass and 7th most abundant by molar percentage. Marine testing

  15. Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent

    SciTech Connect

    Janke, Chris; Yatsandra, Oyola; Mayes, Richard; none,; Gill, Gary; Li-Jung, Kuo; Wood, Jordana; Sadananda, Das

    2014-04-30

    ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

  16. Mars Methane Plume Tracer

    NASA Astrophysics Data System (ADS)

    Mischna, M. A.; Banfield, D.; Sykes, I.

    2014-07-01

    Putative releases of methane from the martian surface may be challenging to detect from orbit. Successful detections depend on the character of the plume itself (duration, magnitude, expanse), but also on the observing platform.

  17. Methane heat transfer investigation

    NASA Technical Reports Server (NTRS)

    Cook, R. T.

    1984-01-01

    Future high chamber pressure LOX/hydrocarbon booster engines require copper-base alloy main combustion chamber coolant channels similar to the SSME to provide adequate cooling and resuable engine life. Therefore, it is of vital importance to evaluate the heat transfer characteristics and coking thresholds for LNG (94% methane) cooling, with a copper-base alloy material adjacent to the fuel coolant. High-pressure methane cooling and coking characteristics were recently evaluated using stainless-steel heated tubes at methane bulk temperatures and coolant wall temperatures typical of advanced engine operation except at lower heat fluxes as limited by the tube material. As expected, there was no coking observed. However, coking evaluations need be conducted with a copper-base surface exposed to the methane coolant at higher heat fluxes approaching those of future high chamber pressure engines.

  18. Methane heat transfer investigation

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Future high chamber pressure LOX/hydrocarbon booster engines require copper base alloy main combustion chamber coolant channels similar to the SSME to provide adequate cooling and reusable engine life. Therefore, it is of vital importance to evaluate the heat transfer characteristics and coking thresholds for LNG (94% methane) cooling, with a copper base alloy material adjacent to he fuel coolant. High pressure methane cooling and coking characteristics recently evaluated at Rocketdyne using stainless steel heated tubes at methane bulk temperatures and coolant wall temperatures typical of advanced engine operation except at lower heat fluxes as limited by the tube material. As expected, there was no coking observed. However, coking evaluations need be conducted with a copper base surface exposed to the methane coolant at higher heat fluxes approaching those of future high chamber pressure engines.

  19. Enzymatic Oxidation of Methane

    SciTech Connect

    Sirajuddin, S; Rosenzweig, AC

    2015-04-14

    Methane monooxygenases (MMOs) are enzymes that catalyze the oxidation of methane to methanol in methanotrophic bacteria. As potential targets for new gas-to-liquid methane bioconversion processes, MMOs have attracted intense attention in recent years. There are two distinct types of MMO, a soluble, cytoplasmic MMO (sMMO) and a membrane-bound, particulate MMO (pMMO). Both oxidize methane at metal centers within a complex, multisubunit scaffold, but the structures, active sites, and chemical mechanisms are completely different. This Current Topic review article focuses on the overall architectures, active site structures, substrate reactivities, proteinprotein interactions, and chemical mechanisms of both MMOs, with an emphasis on fundamental aspects. In addition, recent advances, including new details of interactions between the sMMO components, characterization of sMMO intermediates, and progress toward understanding the pMMO metal centers are highlighted. The work summarized here provides a guide for those interested in exploiting MMOs for biotechnological applications.

  20. Electrochemical methane sensor

    DOEpatents

    Zaromb, S.; Otagawa, T.; Stetter, J.R.

    1984-08-27

    A method and instrument including an electrochemical cell for the detection and measurement of methane in a gas by the oxidation of methane electrochemically at a working electrode in a nonaqueous electrolyte at a voltage about 1.4 volts vs R.H.E. (the reversible hydrogen electrode potential in the same electrolyte), and the measurement of the electrical signal resulting from the electrochemical oxidation.

  1. Laser beam methane detector

    NASA Technical Reports Server (NTRS)

    Hinkley, E. D., Jr.

    1981-01-01

    Instrument uses infrared absorption to determine methane concentration in liquid natural gas vapor. Two sensors measure intensity of 3.39 mm laser beam after it passes through gas; absorption is proportional to concentration of methane. Instrument is used in modeling spread of LNG clouds and as leak detector on LNG carriers and installations. Unit includes wheels for mobility and is both vertically and horizontally operable.

  2. Temperature Sensitive Nanocapsule of Complex Structural Form for Methane Storage

    PubMed Central

    2010-01-01

    The processes of methane adsorption, storage and desorption by the nanocapsule are investigated with molecular-dynamic modeling method. The specific nanocapsule shape defines its functioning uniqueness: methane is adsorbed under 40 MPa and at normal temperature with further blocking of methane molecules the K@C601+ endohedral complex in the nanocapsule by external electric field, the storage is performed under normal external conditions, and methane desorption is performed at 350 K. The methane content in the nanocapsule during storage reaches 11.09 mass%. The nanocapsule consists of tree parts: storage chamber, junction and blocking chamber. The storage chamber comprises the nanotube (20,20). The blocking chamber is a short nanotube (20,20) with three holes. The junction consists of the nanotube (10,10) and nanotube (8,8); moreover, the nanotube (8,8) is connected with the storage chamber and nanotube (10,10) with the blocking chamber. The blocking chamber is opened and closed by the transfer of the K@C601+ endohedral complex under electrostatic field action. PMID:20652146

  3. Low-pressure equilibrium binary argon-methane gas mixture adsorption on exfoliated graphite: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Albesa, Alberto; Russell, Brice; Vicente, José Luis; Rafti, Matías

    2016-04-01

    Adsorption equilibrium measurements of pure methane, pure argon, and binary mixtures over exfoliated graphite were carried for different initial compositions, temperatures, and total pressures in the range of 0.1-1.5 Torr using the volumetric static method. Diagrams for gas and adsorbed phase compositions were constructed for the conditions explored, and isosteric heats of adsorption were calculated. Experimental results were compared with predictions obtained with Monte Carlo simulations and using the Ideal Adsorbed Solution Theory (IAST).

  4. Database of Novel and Emerging Adsorbent Materials

    National Institute of Standards and Technology Data Gateway

    SRD 205 NIST/ARPA-E Database of Novel and Emerging Adsorbent Materials (Web, free access)   The NIST/ARPA-E Database of Novel and Emerging Adsorbent Materials is a free, web-based catalog of adsorbent materials and measured adsorption properties of numerous materials obtained from article entries from the scientific literature. Search fields for the database include adsorbent material, adsorbate gas, experimental conditions (pressure, temperature), and bibliographic information (author, title, journal), and results from queries are provided as a list of articles matching the search parameters. The database also contains adsorption isotherms digitized from the cataloged articles, which can be compared visually online in the web application or exported for offline analysis.

  5. NOx adsorber and method of regenerating same

    DOEpatents

    Endicott, Dennis L.; Verkiel, Maarten; Driscoll, James J.

    2007-01-30

    New technologies, such as NOx adsorber catalytic converters, are being used to meet increasingly stringent regulations on undesirable emissions, including NOx emissions. NOx adsorbers must be periodically regenerated, which requires an increased fuel consumption. The present disclosure includes a method of regenerating a NOx adsorber within a NOx adsorber catalytic converter. At least one sensor positioned downstream from the NOx adsorber senses, in the downstream exhaust, at least one of NOx, nitrous oxide and ammonia concentrations a plurality of times during a regeneration phase. The sensor is in communication with an electronic control module that includes a regeneration monitoring algorithm operable to end the regeneration phase when a time rate of change of the at least one of NOx, nitrous oxide and ammonia concentrations is after an expected plateau region begins.

  6. Fluorescence dynamics of microsphere-adsorbed sunscreens

    NASA Astrophysics Data System (ADS)

    Krishnan, R.

    2005-03-01

    Sunscreens are generally oily substances which are prepared in organic solvents, emulsions or dispersions with micro- or nanoparticles. These molecules adsorb to and integrate into skin cells. In order to understand the photophysical properties of the sunscreen, we compare steady-state and time-resolved fluorescence in organic solvent of varying dielectric constant ɛ and adsorbed to polystyrene microspheres and dispersed in water. Steady-state fluorescence is highest and average fluorescence lifetime longest in toluene, the solvent of lowest ɛ. However, there is no uniform dependence on ɛ. Sunscreens PABA and padimate-O show complex emission spectra. Microsphere-adsorbed sunscreens exhibit highly non-exponential decay, illustrative of multiple environments of the adsorbed molecule. The heterogeneous fluorescence dynamics likely characterizes sunscreen adsorbed to cells.

  7. Palladium dimers adsorbed on graphene: A DFT study

    SciTech Connect

    Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya

    2015-05-15

    The 2D structure of graphene shows a great promise for enhanced catalytic activity when adsorbed with palladium. We performed a systematic density functional theory (DFT) study of the adsorption of palladium dimer (Pd{sub 2}) on graphene using SIESTA package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Pd{sub 2}-graphene system are calculated. Both horizontal and vertical orientations of Pd{sub 2} on graphene are studied. Our calculations revealed that the minimum energy configuration for Pd dimer is parallel to the graphene sheet with its two atoms occupying centre of adjacent hexagonal rings of graphene sheet. Magnetic moment is induced for Pd dimer adsorbed on graphene in vertical orientation while horizontal orientation of Pd dimer on graphene do not exhibit magnetism. Insignificant energy differences among adsorption sites means that dimer mobility on the graphene sheet is high. There is imperceptible distortion of graphene sheet perpendicular to its plane. However, some lateral displacements are seen.

  8. Job Displacement Among Single Mothers:

    PubMed Central

    Brand, Jennie E.; Thomas, Juli Simon

    2015-01-01

    Given the recent era of economic upheaval, studying the effects of job displacement has seldom been so timely and consequential. Despite a large literature associating displacement with worker well-being, relatively few studies focus on the effects of parental displacement on child well-being, and fewer still focus on implications for children of single parent households. Moreover, notwithstanding a large literature on the relationship between single motherhood and children’s outcomes, research on intergenerational effects of involuntary employment separations among single mothers is limited. Using 30 years of nationally representative panel data and propensity score matching methods, we find significant negative effects of job displacement among single mothers on children’s educational attainment and social-psychological well-being in young adulthood. Effects are concentrated among older children and children whose mothers had a low likelihood of displacement, suggesting an important role for social stigma and relative deprivation in the effects of socioeconomic shocks on child well-being. PMID:25032267

  9. Methane Emissions from Upland Forests

    NASA Astrophysics Data System (ADS)

    Megonigal, Patrick; Pitz, Scott; Wang, Zhi-Ping

    2016-04-01

    Global budgets ascribe 4-10% of atmospheric methane sinks to upland soils and assume that soils are the sole surface for methane exchange between upland forests and the atmosphere. The dogma that upland forests are uniformly atmospheric methane sinks was challenged a decade ago by the discovery of abiotic methane production from plant tissue. Subsequently a variety of relatively cryptic microbial and non-microbial methane sources have been proposed that have the potential to emit methane in upland forests. Despite the accumulating evidence of potential methane sources, there are few data demonstrating actual emissions of methane from a plant surface in an upland forest. We report direct observations of methane emissions from upland tree stems in two temperate forests. Stem methane emissions were observed from several tree species that dominate a forest located on the mid-Atlantic coast of North America (Maryland, USA). Stem emissions occurred throughout the growing season while soils adjacent to the trees simultaneously consumed methane. Scaling fluxes by stem surface area suggested the forest was a net methane source during a wet period in June, and that stem emissions offset 5% of the soil methane sink on an annual basis. High frequency measurements revealed diurnal cycles in stem methane emission rates, pointing to soils as the methane source and transpiration as the most likely pathway for gas transport. Similar observations were made in an upland forest in Beijing, China. However, in this case the evidence suggested the methane was not produced in soils, but in the heartwood by microbial or non-microbial processes. These data challenge the concept that forests are uniform sinks of methane, and suggest that upland forests are smaller methane sinks than previously estimated due to stem emissions. Tree emissions may be particularly important in upland tropical forests characterized by high rainfall and transpiration.

  10. Enhanced electrochemical methanation of carbon dioxide with a dispersible nanoscale copper catalyst.

    PubMed

    Manthiram, Karthish; Beberwyck, Brandon J; Alivisatos, A Paul

    2014-09-24

    Although the vast majority of hydrocarbon fuels and products are presently derived from petroleum, there is much interest in the development of routes for synthesizing these same products by hydrogenating CO2. The simplest hydrocarbon target is methane, which can utilize existing infrastructure for natural gas storage, distribution, and consumption. Electrochemical methods for methanizing CO2 currently suffer from a combination of low activities and poor selectivities. We demonstrate that copper nanoparticles supported on glassy carbon (n-Cu/C) achieve up to 4 times greater methanation current densities compared to high-purity copper foil electrodes. The n-Cu/C electrocatalyst also exhibits an average Faradaic efficiency for methanation of 80% during extended electrolysis, the highest Faradaic efficiency for room-temperature methanation reported to date. We find that the level of copper catalyst loading on the glassy carbon support has an enormous impact on the morphology of the copper under catalytic conditions and the resulting Faradaic efficiency for methane. The improved activity and Faradaic efficiency for methanation involves a mechanism that is distinct from what is generally thought to occur on copper foils. Electrochemical data indicate that the early steps of methanation on n-Cu/C involve a pre-equilibrium one-electron transfer to CO2 to form an adsorbed radical, followed by a rate-limiting non-electrochemical step in which the adsorbed CO2 radical reacts with a second CO2 molecule from solution. These nanoscale copper electrocatalysts represent a first step toward the preparation of practical methanation catalysts that can be incorporated into membrane-electrode assemblies in electrolyzers.

  11. Enhanced electrochemical methanation of carbon dioxide with a dispersible nanoscale copper catalyst.

    PubMed

    Manthiram, Karthish; Beberwyck, Brandon J; Alivisatos, A Paul

    2014-09-24

    Although the vast majority of hydrocarbon fuels and products are presently derived from petroleum, there is much interest in the development of routes for synthesizing these same products by hydrogenating CO2. The simplest hydrocarbon target is methane, which can utilize existing infrastructure for natural gas storage, distribution, and consumption. Electrochemical methods for methanizing CO2 currently suffer from a combination of low activities and poor selectivities. We demonstrate that copper nanoparticles supported on glassy carbon (n-Cu/C) achieve up to 4 times greater methanation current densities compared to high-purity copper foil electrodes. The n-Cu/C electrocatalyst also exhibits an average Faradaic efficiency for methanation of 80% during extended electrolysis, the highest Faradaic efficiency for room-temperature methanation reported to date. We find that the level of copper catalyst loading on the glassy carbon support has an enormous impact on the morphology of the copper under catalytic conditions and the resulting Faradaic efficiency for methane. The improved activity and Faradaic efficiency for methanation involves a mechanism that is distinct from what is generally thought to occur on copper foils. Electrochemical data indicate that the early steps of methanation on n-Cu/C involve a pre-equilibrium one-electron transfer to CO2 to form an adsorbed radical, followed by a rate-limiting non-electrochemical step in which the adsorbed CO2 radical reacts with a second CO2 molecule from solution. These nanoscale copper electrocatalysts represent a first step toward the preparation of practical methanation catalysts that can be incorporated into membrane-electrode assemblies in electrolyzers. PMID:25137433

  12. Inorganic chemically active adsorbents (ICAAs)

    SciTech Connect

    Ally, M.R.; Tavlarides, L.

    1997-10-01

    Oak Ridge National Laboratory (ORNL) researchers are developing a technology that combines metal chelation extraction technology and synthesis chemistry. They begin with a ceramic substrate such as alumina, titanium oxide or silica gel because they provide high surface area, high mechanical strength, and radiolytic stability. One preparation method involves silylation to hydrophobize the surface, followed by chemisorption of a suitable chelation agent using vapor deposition. Another route attaches newly designed chelating agents through covalent bonding by the use of coupling agents. These approaches provide stable and selective, inorganic chemically active adsorbents (ICAAs) tailored for removal of metals. The technology has the following advantages over ion exchange: (1) higher mechanical strength, (2) higher resistance to radiation fields, (3) higher selectivity for the desired metal ion, (4) no cation exchange, (5) reduced or no interference from accompanying anions, (6) faster kinetics, and (7) easy and selective regeneration. Target waste streams include metal-containing groundwater/process wastewater at ORNL`s Y-12 Plant (multiple metals), Savannah River Site (SRS), Rocky Flats (multiple metals), and Hanford; aqueous mixed wastes at Idaho National Engineering Laboratory (INEL); and scrubber water generated at SRS and INEL. Focus Areas that will benefit from this research include Mixed Waste, and Subsurface Contaminants.

  13. Dual pressure displacement control system

    SciTech Connect

    Louis, J.E.; Klocke, C.C.

    1988-02-02

    This patent describes a dual pressure servo control system for a variable displacement hydraulic unit having displacement setting means positioned by a hydraulic servo mechanism. The hydraulic unit is provided with main loop lines at least one of which is capable of being subjected to high main loop pressure during operation of the hydraulic unit, a control line including a displacement control valve providing a controlled flow of fluid under pressure to the servo mechanism, and a source of fluid under pressure for the control line comprising a low pressure source connected to the control line through a check valve and high pressure source comprising of a high pressure control line connected to the control line downstream of the check valve. The high pressure control line includes a flow restriction limiting flow to the control line means and generating a significant flow induced pressure drop in the high pressure control line once movement in the servo mechanism is initiated.

  14. Perceived displacement explains wolfpack effect

    PubMed Central

    Šimkovic, Matúš; Träuble, Birgit

    2014-01-01

    We investigate the influence of perceived displacement of moving agent-like stimuli on the performance in dynamic interactive tasks. In order to reliably measure perceived displacement we utilize multiple tasks with different task demands. The perceived center of an agent's body is displaced in the direction in which the agent is facing and this perceived displacement is larger than the theoretical position of the center of mass would predict. Furthermore, the displacement in the explicit judgment is dissociated from the displacement obtained by the implicit measures. By manipulating the location of the pivot point, we show that it is not necessary to postulate orientation as an additional cue utilized by perception, as has been suggested by earlier studies. These studies showed that the agent's orientation influences the detection of chasing motion and the detection-related performance in interactive tasks. This influence has been labeled wolfpack effect. In one of the demonstrations of the wolfpack effect participants control a green circle on a display with a computer mouse. It has been shown that participants avoid display areas with agents pointing toward the green circle. Participants do so in favor of areas where the agents point in the direction perpendicular to the circle. We show that this avoidance behavior arises because the agent's pivot point selected by the earlier studies is different from where people locate the center of agent's body. As a consequence, the nominal rotation confounds rotation and translation. We show that the avoidance behavior disappears once the pivot point is set to the center of agent's body. PMID:25566114

  15. Extension - Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption

    SciTech Connect

    Anna Lee Tonkovich

    2008-08-11

    The need for cost effective technologies for upgrading coal mine methane to pipeline quality natural gas is becoming ever greater. The current work presents and investigates a new approach to reduce the impact of the most costly step in the conventional technology, nitrogen rejection. The proposed approach is based on the Velocys microchannel platform, which is being developed to commercialize compact and cost efficient chemical processing technology. For this separation, ultra fast thermal swing sorption is enabled by the very high rates of heat and mass transfer inherent in microchannel processing. In a first phase of the project solid adsorbents were explored. Feasibility of ultrafast thermal swing was demonstrated but the available adsorbents had insufficient differential methane capacity to achieve the required commercial economics. In a second phase, ionic liquids were adopted as absorbents of choice, and experimental work and economic analyses, performed to gauge their potential, showed promise for this novel alternative. Final conclusions suggest that a combination of a required cost target for ionic liquids or a methane capacity increase or a combination of both is required for commercialization.

  16. Methane adsorption on the surface of a model of shale: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Zhu, Yuan-qiang; Su, Hong; Jing, Ya; Guo, Jianchun; Tang, Junlei

    2016-11-01

    As a model of shale, one part of polycyclic aromatic ring was used to represent the kerogen surface with the structural heterogeneity. The adsorption mechanisms of methane on the surface of the kerogen were investigated by M06-2× functional with D3 dispersion correction. Nine stable adsorption sites and the orientations of methane (CH4) on the surface of the kerogen were systematically considered. Information from different methods lead to the same conclusion that methane prefers to be adsorbed on the sites directly above the carbon atoms of the kerogen rather than above the center of the six-membered rings. The interactions between methane and the surface of the kerogen are the van der Waals interactions. The interaction energies with the basis set superposition error (BSSE) corrections are around 14 kJ mol-1 at the M06-2×-D3/Jun-cc-pVDZ level. The RDG scatter graphs and the RDG gradient isosurface further illustrate that the interactions between methane and the surface of the kerogen belong to the van der Waals interactions. The weak interactions indicate that the adsorption of methane on the surface of the kerogen is physical adsorption and it slightly depends upon the adsorption sites on kerogen as well as the orientations of methane. These results are helpful for the understanding of the microcosmic mechanism of methane-shale interactions and for the exploitation of shale gas.

  17. Particle displacement tracking for PIV

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.

    1990-01-01

    A new Particle Imaging Velocimetry (PIV) data acquisition and analysis system, which is an order of magnitude faster than any previously proposed system has been constructed and tested. The new Particle Displacement Tracing (PDT) system is an all electronic technique employing a video camera and a large memory buffer frame-grabber board. Using a simple encoding scheme, a time sequence of single exposure images are time coded into a single image and then processed to track particle displacements and determine velocity vectors. Application of the PDT technique to a counter-rotating vortex flow produced over 1100 velocity vectors in 110 seconds when processed on an 80386 PC.

  18. Rotor component displacement measurement system

    DOEpatents

    Mercer, Gary D.; Li, Ming C.; Baum, Charles R.

    2003-05-27

    A measuring system for measuring axial displacement of a tube relative to an axially stationary component in a rotating rotor assembly includes at least one displacement sensor adapted to be located normal to a longitudinal axis of the tube; an insulated cable system adapted for passage through the rotor assembly; a rotatable proximitor module located axially beyond the rotor assembly to which the cables are connected; and a telemetry system operatively connected to the proximitor module for sampling signals from the proximitor module and forwarding data to a ground station.

  19. Heat transfer to the adsorbent in solar adsorption cooling device

    NASA Astrophysics Data System (ADS)

    Pilat, Peter; Patsch, Marek; Papucik, Stefan; Vantuch, Martin

    2014-08-01

    The article deals with design and construction of solar adsorption cooling device and with heat transfer problem in adsorber. The most important part of adsorption cooling system is adsorber/desorber containing adsorbent. Zeolith (adsorbent) type was chosen for its high adsorption capacity, like a coolant was used water. In adsorber/desorber occur, at heating of adsorbent, to heat transfer from heat change medium to the adsorbent. The time required for heating of adsorber filling is very important, because on it depend flexibility of cooling system. Zeolith has a large thermal resistance, therefore it had to be adapted the design and construction of adsorber. As the best shows the tube type of adsorber with double coat construction. By this construction is ensured thin layer of adsorbent and heating is quick in all volume of adsorbent. The process of heat transfer was experimentally measured, but for comparison simulated in ANSYS, too.

  20. Characteristics of slush and boiling methane and methane mixtures.

    NASA Technical Reports Server (NTRS)

    Sindt, C. F.; Ludtke, P. R.

    1971-01-01

    Methane gas of two purities, 99.97% and 99%, was condensed to study the characteristics of the boiling liquid and the slush. In addition, binary mixtures of nitrogen and methane, and those of ethane and methane, and propane and methane, were also studied. Potential advantages of these gases when employed as fuels for high-performance aircraft, rocket engines, and motor vehicles are emphasized.

  1. Combustion of Methane Hydrate

    NASA Astrophysics Data System (ADS)

    Roshandell, Melika

    A significant methane storehouse is in the form of methane hydrates on the sea floor and in the arctic permafrost. Methane hydrates are ice-like structures composed of water cages housing a guest methane molecule. This caged methane represents a resource of energy and a potential source of strong greenhouse gas. Most research related to methane hydrates has been focused on their formation and dissociation because they can form solid plugs that complicate transport of oil and gas in pipelines. This dissertation explores the direct burning of these methane hydrates where heat from the combustion process dissociates the hydrate into water and methane, and the released methane fuels the methane/air diffusion flame heat source. In contrast to the pipeline applications, very little research has been done on the combustion and burning characteristics of methane hydrates. This is the first dissertation on this subject. In this study, energy release and combustion characteristics of methane hydrates were investigated both theoretically and experimentally. The experimental study involved collaboration with another research group, particularly in the creation of methane hydrate samples. The experiments were difficult because hydrates form at high pressure within a narrow temperature range. The process can be slow and the resulting hydrate can have somewhat variable properties (e.g., extent of clathration, shape, compactness). The experimental study examined broad characteristics of hydrate combustion, including flame appearance, burning time, conditions leading to flame extinguishment, the amount of hydrate water melted versus evaporated, and flame temperature. These properties were observed for samples of different physical size. Hydrate formation is a very slow process with pure water and methane. The addition of small amounts of surfactant increased substantially the hydrate formation rate. The effects of surfactant on burning characteristics were also studied. One finding

  2. Adsorbed natural gas storage with activated carbon

    SciTech Connect

    Sun, Jian; Brady, T.A.; Rood, M.J.

    1996-12-31

    Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

  3. States of water adsorbed on perindopril crystals

    NASA Astrophysics Data System (ADS)

    Stepanov, V. A.; Khmelevskaya, V. S.; Bogdanov, N. Yu.; Gorchakov, K. A.

    2011-10-01

    The relationship between the structural state of adsorbed water, the crystal structure of the substances, and the solubility of the perindopril salt C19H32N2O5 · C4H11N in water was studied by IR spectroscopy and X-ray diffractometry. The high-frequency shift of the stretching vibrations of adsorbed water and the solubility depend on the crystal structure of the drug substance. A reversible chemical reaction occurred between the adsorbed water and the perindopril salt.

  4. Volumetric Interpretation of Protein Adsorption: Capacity Scaling with Adsorbate Molecular Weight and Adsorbent Surface Energy

    PubMed Central

    Parhi, Purnendu; Golas, Avantika; Barnthip, Naris; Noh, Hyeran; Vogler, Erwin A.

    2009-01-01

    Silanized-glass-particle adsorbent capacities are extracted from adsorption isotherms of human serum albumin (HSA, 66 kDa), immunoglobulin G (IgG, 160 kDa), fibrinogen (Fib, 341 kDa), and immunoglobulin M (IgM, 1000 kDa) for adsorbent surface energies sampling the observable range of water wettability. Adsorbent capacity expressed as either mass-or-moles per-unit-adsorbent-area increases with protein molecular weight (MW) in a manner that is quantitatively inconsistent with the idea that proteins adsorb as a monolayer at the solution-material interface in any physically-realizable configuration or state of denaturation. Capacity decreases monotonically with increasing adsorbent hydrophilicity to the limit-of-detection (LOD) near τo = 30 dyne/cm (θ~65o) for all protein/surface combinations studied (where τo≡γlvocosθ is the water adhesion tension, γlvo is the interfacial tension of pure-buffer solution, and θ is the buffer advancing contact angle). Experimental evidence thus shows that adsorbent capacity depends on both adsorbent surface energy and adsorbate size. Comparison of theory to experiment implies that proteins do not adsorb onto a two-dimensional (2D) interfacial plane as frequently depicted in the literature but rather partition from solution into a three-dimensional (3D) interphase region that separates the physical surface from bulk solution. This interphase has a finite volume related to the dimensions of hydrated protein in the adsorbed state (defining “layer” thickness). The interphase can be comprised of a number of adsorbed-protein layers depending on the solution concentration in which adsorbent is immersed, molecular volume of the adsorbing protein (proportional to MW), and adsorbent hydrophilicity. Multilayer adsorption accounts for adsorbent capacity over-and-above monolayer and is inconsistent with the idea that protein adsorbs to surfaces primarily through protein/surface interactions because proteins within second (or higher

  5. 20 CFR 627.230 - Displacement.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 3 2012-04-01 2012-04-01 false Displacement. 627.230 Section 627.230... PROGRAMS UNDER TITLES I, II, AND III OF THE ACT Program Requirements § 627.230 Displacement. (a) No currently employed worker shall be displaced by any participant (including partial displacement such as...

  6. 20 CFR 627.230 - Displacement.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Displacement. 627.230 Section 627.230... PROGRAMS UNDER TITLES I, II, AND III OF THE ACT Program Requirements § 627.230 Displacement. (a) No currently employed worker shall be displaced by any participant (including partial displacement such as...

  7. 20 CFR 627.230 - Displacement.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Displacement. 627.230 Section 627.230... PROGRAMS UNDER TITLES I, II, AND III OF THE ACT Program Requirements § 627.230 Displacement. (a) No currently employed worker shall be displaced by any participant (including partial displacement such as...

  8. Methane formation and methane oxidation by methanogenic bacteria.

    PubMed Central

    Zehnder, A J; Brock, T D

    1979-01-01

    Methanogenic bacteria were found to form and oxidize methane at the same time. As compared to the quantity of methane formed, the amount of methane simultaneously oxidized varied between 0.3 and 0.001%, depending on the strain used. All the nine tested strains of methane producers (Methanobacterium ruminantium, Methanobacterium strain M.o.H., M. formicicum, M. thermoautotrophicum, M. arbophilicum, Methanobacterium strain AZ, Methanosarcina barkeri, Methanospirillum hungatii, and the "acetate organism") reoxidized methane to carbon dioxide. In addition, they assimilated a small part of the methane supplied into cell material. Methanol and acetate also occurred as oxidation products in M. barkeri cultures. Acetate was also formed by the "acetate organism," a methane bacterium unable to use methanogenic substrates other than acetate. Methane was the precursor of the methyl group of the acetate synthesized in the course of methane oxidation. Methane formation and its oxidation were inhibited equally by 2-bromoethanesulfonic acid. Short-term labeling experiments with M. thermoautotrophicum and M. hungatii clearly suggest that the pathway of methane oxidation is not identical with a simple back reaction of the methane formation process. Images PMID:762019

  9. Retraining Displaced Workers. Policy Brief

    ERIC Educational Resources Information Center

    LaLonde, Robert; Sullivan, Daniel

    2010-01-01

    Robert LaLonde of the University of Chicago and Daniel Sullivan of the Federal Reserve Bank of Chicago suggest that retraining through our nation's community colleges is a way to reduce the skills gaps of at least some of these displaced workers and increase their reemployment earnings. Although workers may still experience significant earnings…

  10. Polybenzimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Hergenrother, Paul M.; Smith, Joseph G.

    1994-01-01

    Soluble polybenzimidazoles (PBI's) synthesized by nucleophilic displacement reaction of di(hydroxyphenyl)-benzimidazole monomers with activated aromatic difluoride compounds in presence of anhydrous potassium carbonate. These polymers exhibit good thermal, thermo-oxidative, and chemical stability, and high mechanical properties. Using benzimidazole monomers, more economical, and new PBI's processed more easily than commercial PBI, without loss of desirable physical properties.

  11. Hypotheses for a Near-Surface Reservoir of Methane and Its Release on Mars

    NASA Astrophysics Data System (ADS)

    Hu, R.; Bloom, A. A.; Gao, P.; Miller, C. E.; Yung, Y. L.

    2015-12-01

    The Curiosity rover recently detected a background of 0.7 ppb and spikes of 7 ppb of methane on Mars. This in situ measurement reorients our understanding of the Martian environment and its potential for life, as the current theories do not entail any active source or sink of methane. In particular, the 10-fold elevation during the southern winter indicates episodic sources of methane that are yet to be discovered. Using the temperature and humidity measurements from the rover, we find that perchlorate salts in the regolith deliquesce to form liquid solutions, and deliquescence progresses to deeper subsurface in the season of the methane spikes. We therefore formulate the following three testable hypotheses as an attempt to explain the apparent variability of the atmospheric methane abundance. The first scenario is that the regolith in Gale Crater adsorbs methane when dry and releases this methane to the atmosphere upon deliquescence. The adsorption energy needs to be 36 kJ mol-1 to explain the magnitude of the methane spikes, higher than laboratory measurements. The second scenario is that microorganisms exist and convert organic matter in the soil to methane when they are in liquid solutions. This scenario does not require regolith adsorption. The third scenario is that deep subsurface aquifers sealed by ice or clathrate produce bursts of methane as a result of freezing and thawing of the permafrost, as the terrestrial arctic tundra. Continued monitoring of methane by Curiosity will test the existence of the near-surface reservoir and its exchange with the atmosphere.

  12. Transformations in methane hydrates

    USGS Publications Warehouse

    Chou, I.-Ming; Sharma, A.; Burruss, R.C.; Shu, J.; Mao, Ho-kwang; Hemley, R.J.; Goncharov, A.F.; Stern, L.A.; Kirby, S.H.

    2000-01-01

    Detailed study of pure methane hydrate in a diamond cell with in situ optical, Raman, and x-ray microprobe techniques reveals two previously unknown structures, structure II and structure H, at high pressures. The structure II methane hydrate at 250 MPa has a cubic unit cell of a = 17.158(2) A?? and volume V = 5051.3(13) A??3; structure H at 600 MPa has a hexagonal unit cell of a = 11.980(2) A??, c = 9.992(3) A??, and V = 1241.9(5) A??3. The compositions of these two investigated phases are still not known. With the effects of pressure and the presence of other gases in the structure, the structure II phase is likely to dominate over the known structure I methane hydrate within deep hydrate-bearing sediments underlying continental margins.

  13. Displacement enzyme linked aptamer assay.

    PubMed

    Baldrich, Eva; Acero, Josep Lluis; Reekmans, Gunter; Laureyn, Wim; O'Sullivan, Ciara K

    2005-08-01

    Immense effort has been placed on the realization of immunoassays exploiting displacement of a suboptimum target, due to the ease of use and applicability to immunochromatographic strips and immunosensors. Most of the efforts reported to date focus on the use of a suboptimal target that is displaceable by the target toward which the antibody has higher affinity. Limited success has been achieved due to difficulty in obtaining suboptimal targets to which the antibody has enough affinity to bind while at the same time having lower levels of affinity in comparison to the target to facilitate displacement. Aptamers are synthetic oligonucleotides specifically selected to bind a certain target. Thanks to their high affinity and sensitivity, aptamers appear as alternative candidates to antibodies for analytical devices and several enzyme-linked aptamer assays and aptasensors have been reported. Aptamers, in contrast to antibodies, require the formation of a three-dimensional structure for target binding and can thus be anticipated to have a much higher affinity for binding its target rather than a modified form of the target (e.g., enzyme-labeled target). This phenomenon can be exploited for the development of a displacement assay, using enzyme-labeled target as a suboptimal displaceable molecule. Here, we report the first demonstration of the exploitation of an aptamer in an extremely rapid and highly sensitive displacement assay. Surface plasmon resonance studies demonstrated the thrombin-binding aptamer to have a lower affinity for enzyme-labeled thrombin than unmodified thrombin, with respective K(D) of 1.1 x 10(-8) and 2.9 x 10(-9) M. The assay is extremely rapid, requiring only 10 min for completion, and exhibits a detection limit lower than that obtainable with competitive enzyme-linked aptamer assays and comparable to that of hybrid aptamer-antibody assays. Optimal storage conditions for precoated microtiter plates (consisting of coated aptamer and captured

  14. PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

    EPA Science Inventory

    Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

  15. Methane in the lunar exosphere: Implications for solar wind carbon escape

    NASA Astrophysics Data System (ADS)

    Hodges, , R. Richard

    2016-07-01

    A positive identification of methane in the lunar exosphere has been made in data from the neutral mass spectrometer on the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft. Like argon-40, methane is adsorbed on the lunar surface during nighttime. However, higher activation energies for methane delay its desorption at sunrise by about an hour local time, creating a postsunrise bulge with peak concentration of approximately 400-450 molecules cm-3 at a reference altitude of 12 km, which is just above the highest topographic feature on the Moon. The rate of escape of carbon as methane derived from the LADEE data is estimated to be in the range 1.5-4.5 × 1021 s-1. A lower bound for solar carbon escape derived separately from Apollo sample analyses is 3.4 × 1021 s-1.

  16. Methane-Powered Airplane

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Beech Aircraft's Corporation's Boulder Division developed expertise in producing superinsulated virtually leak-proof cryogenic equipment for storing liquid oxygen and hydrogen fuels in NASA's Apollo, Skylab and Space Shuttle programs. Boulder Division used this experience in designing a fuel storage tank for liquid methane, a "cryogenic" fuel that must be supercooled to keep it liquid. Beech Aircraft is producing a four-place lightplane powered by liquid methane (LM) which is stored in two of these specially designed cryogenic storage tanks holding 18 gallons each.

  17. Biomimetic methane oxidation

    SciTech Connect

    Watkins, B.E.; Droege, M.W.; Taylor, R.T.; Satcher, J.H.

    1992-06-12

    Methane monooxygenase (MMO) is an enzyme found in methanotrophs that catalyses the selective oxidation of methane to methanol. MMO is protein complex one component of which is a binuclear metal center containing oxygenase. We have completed one round of a design/synthesis/evaluation cycle in the development of coordination complexes that mimic the structure/function of the MMO active site. One of these, a binuclear, coordinately-asymmetric copper complex, is capable of oxidizing cyclohexane to a mixture of cyclohexanol and cyclohexanone in the presence of hydrogen peroxide.

  18. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, Sheldon H. D.

    1992-01-01

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases.

  19. Regenerable activated bauxite adsorbent alkali monitor probe

    DOEpatents

    Lee, S.H.D.

    1992-12-22

    A regenerable activated bauxite adsorber alkali monitor probe for field applications to provide reliable measurement of alkali-vapor concentration in combustion gas with special emphasis on pressurized fluidized-bed combustion (PFBC) off-gas. More particularly, the invention relates to the development of a easily regenerable bauxite adsorbent for use in a method to accurately determine the alkali-vapor content of PFBC exhaust gases. 6 figs.

  20. Mesoporous Silica: A Suitable Adsorbent for Amines

    PubMed Central

    2009-01-01

    Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices. PMID:20628459

  1. Hydrophobic Porous Material Adsorbs Small Organic Molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K.; Hickey, Gregory S.

    1994-01-01

    Composite molecular-sieve material has pore structure designed specifically for preferential adsorption of organic molecules for sizes ranging from 3 to 6 angstrom. Design based on principle that contaminant molecules become strongly bound to surface of adsorbent when size of contaminant molecules is nearly same as that of pores in adsorbent. Material used to remove small organic contaminant molecules from vacuum systems or from enclosed gaseous environments like closed-loop life-support systems.

  2. Free displacer and Ringbom displacer for a Malone refrigerator

    SciTech Connect

    Swift, G.W.; Brown, A.O.

    1994-05-01

    Malone refrigeration uses a liquid near its critical point (instead of the customary gas) as the working fluid in a Stirling, Brayton, or similar regenerative or recuperative cycle. Thus far, we have focused on the Stirling cycle, to avoid the difficult construction of the high-pressure-difference counterflow recuperator required for a Brayton machine. Our first Malone refrigerator used liquid propylene (C{sub 3}H{sub 6}) in a double-acting 4-cylinder Stirling configuration. First measurements with a free displacer used in a liquid working fluid are presented. The displacer was operated both in harmonic mode and in Ringbom mode, in liquid carbon dioxide. The results are in reasonable agreement with expectations.

  3. Probing of Competitive Displacement Adsorption of Casein at Oil-in-Water Interface Using Equilibrium Force Distance Measurements.

    PubMed

    Mahendran, V; Sangeetha, J; Philip, John

    2015-06-01

    The equilibrium force distance measurement is employed for the first time to probe the competitive and displacement adsorption of casein at an oil-water (O/W) emulsion interface that was initially adsorbed with either a diblock polymer or an anionic surfactant. A significant change in the force-distance profile was observed under the competitive displacement adsorption of casein, which is further confirmed from the hydrodynamic diameter and zeta potential measurements. A decrease in the onset of repulsion and decay length are observed on competitive adsorption of smaller size casein molecules at O/W interface. With addition of casein in PVA-vac diblock polymer stabilized emulsion, the onset of repulsion decreases from 88 to 48 nm whereas the magnitude of force increases from 1 to 19 nN. The force decay length is reduced from 10.5 to 4.5 nm upon addition of casein. Our results suggest the complete replacement of adsorbed diblock polymers by casein molecules. The hydrodynamic diameter and zeta potential measurements corroborate the casein mediated polymer displacement and the competitive adsorption of casein at the O/W interface. In the case of anionic surfactant covered O/W interfaces, casein molecules weakly associate at the interface without displacing the smaller size surfactant molecules where no significant changes in the onset repulsion and force profiles are observed. These results suggest that the casein molecules are effective displacers for replacement of adsorbed macromolecules from formulations, which has several important practical applications.

  4. Some Considerations on Horizontal Displacement and Horizontal Displacement Coefficient B

    NASA Astrophysics Data System (ADS)

    Tajduś, Krzysztof; Tajduś, Antoni

    2015-12-01

    Mining-induced deformations of the ground surface and within the rock mass may pose danger not only for surface constructions but also for underground objects (e.g., tunnels, underground storages, garages), diverse types of pipelines, electric cables, etc. For a proper evaluation of hazard for surface and underground objects, such parameters as horizontal displacement and horizontal deformations, especially their maximum values, are of crucial importance. The paper is an attempt at a critical review of hitherto accomplished studies and state of the art of predicting horizontal displacement u, in particular the coefficient B, whose value allows determination of the value of maximum displacement if the value of maximum slope is known, or the value of maximum deformation if the value of maximum trough slope is recognized. Since the geodesic observations of fully developed subsidence troughs suggest that the value of the coefficient depends on the depth H, radius of main influences range r and properties of overburden rock, in particular the occurrence of sub-eras Paleogene and Neogene layers (old name: Quaternary and Tertiary) with low strength parameters, therefore a formula is provided in the present paper allowing for the estimation of the influence of those factors on the value of coefficient B.

  5. K2S-activated carbons developed from coal and their methane adsorption behaviors

    NASA Astrophysics Data System (ADS)

    Feng, Yan-Yan; Yang, Wen; Chu, Wei

    2014-10-01

    The main purpose of this work is to prepare various activated carbons by K2S activation of coal with size fractions of 60-80 meshes, and investigate the microporosity development and corresponding methane storage capacities. Raw coal is mixed with K2S powder, and then heated at 750 °C-900 °C for 30 min-150 min in N2 atmosphere to produce the adsorbents. The texture and surface morphology are characterized by a N2 adsorption/desorption isotherm at 77 K and scanning electron microscopy (SEM). The chemical properties of carbons are confirmed by ultimate analysis. The crystal structure and degree of graphitization are tested by X-ray diffraction and Raman spectra. The relationship between sulfur content and the specific surface area of the adsorbents is also determined. K2S activation is helps to bring about better development of pore texture. These adsorbents are microporous materials with textural parameters increasing in a range of specific surface area 72.27 m2/g-657.7 m2/g and micropore volume 0.035 cm3/g-0.334 cm3/g. The ability of activated carbons to adsorb methane is measured at 298 K and at pressures up to 5.0 MPa by a volumetric method. The Langmuir model fits the experimental data well. It is concluded that the high specific surface area and micropore volume of activated carbons do determine methane adsorption capacity. The adsorbents obtained at 800 °C for 90 min with K2S/raw coal mass ratios of 1.0 and 1.2 show the highest methane adsorption capacities amounting to 106.98 mg/g and 106.17 mg/g, respectively.

  6. Modified Newmark method involving excess pore pressure to express unlimited landslide displacement

    NASA Astrophysics Data System (ADS)

    Fukuoka, H.; Tsukui, A.

    2012-12-01

    Newmark method is the most popular approach to assess the displacement of landslides induced by earthquakes using seismic acceleration, slope inclination, and friction parameters. However, this method always shows limited shear displacement no matter how the acceleration is large and duration is long. This is partly because it does not include any pore pressure, especially excess pore water pressure generated under long shear displacement. As shown by series of earthquake wave-form loading undrained ring shear tests by Disaster Prevention Research Institute of Kyoto University, grain crushing or soil skelton collapse can contribute to generation of high excess pore pressure and let the soil to reach liquefaction state ("Sliding surface liquefaction"). Many of unlimited landslide displacement have been revealed that this phenomena must be the key mechanism. In the test series of mixture of silica sands and dry-ice pellets (frozen carbon-dioxide), for studying the mechanism of the gasification of methane hydrates in the submarine landslides which likely to trigger large scale submarine landslides, authors have found linear relationship between log of excess pore pressure ratio (generated pore pressure / initial effective normal stress) and log of shear displacement. By embedding this relation into the Newmark method, unlimited shear displacement can appear under certain slope inclination and exaggerated acceleration. Authors show there is critical slope inclination for unlimited displacement when given acceleration waveform.

  7. Multiple displacement motor driven power drive unit

    SciTech Connect

    Burandt, W. A.

    1985-12-03

    A multiple displacement motor driven power drive unit having two separate hydraulic systems each with a variable displacement hydraulic motor having its output connected to a torque summing gear train. A control provides for operation of one or the other of the motors at full displacement while the other motor is at zero displacement and free-wheels. There is a manual mechanical control operation with both motors simultaneously set at one-half of full displacement and driving the torque summing gear train. The change in motor displacements to one-half full displacement accomplishes velocity summing within the hydraulics. The multiple displacement motor driven power drive unit accomplishes the power efficiency of a multiple motor driven power drive unit utilizing a speed summing gear train with fixed displacement motors, but without the complexities associated with the use of a speed summing gear train and brakes.

  8. Methane emissions from natural wetlands

    SciTech Connect

    Meyer, J.L.; Burke, R.A. Jr.

    1993-09-01

    Analyses of air trapped in polar ice cores in conjunction with recent atmospheric measurements, indicate that the atmospheric methane concentration increased by about 250% during the past two or three hundred years (Rasmussen and Khalil, 1984). Because methane is a potent ``greenhouse`` gas, the increasing concentrations are expected to contribute to global warning (Dickinson and Cicerone, 1986). The timing of the methane increase suggests that it is related to the rapid growth of the human population and associated industrialization and agricultural development. The specific causes of the atmospheric methane concentration increase are not well known, but may relate to either increases in methane sources, decreases in the strengths of the sinks, or both.

  9. Direct Aromaization of Methane

    SciTech Connect

    George Marcelin

    1997-01-15

    The thermal decomposition of methane offers significant potential as a means of producing higher unsaturated and aromatic hydrocarbons when the extent of reaction is limited. Work in the literature previous to this project had shown that cooling the product and reacting gases as the reaction proceeds would significantly reduce or eliminate the formation of solid carbon or heavier (Clo+) materials. This project studied the effect and optimization of the quenching process as a means of increasing the amount of value added products during the pyrolysis of methane. A reactor was designed to rapidly quench the free-radical combustion reaction so as to maximize the yield of aromatics. The use of free-radical generators and catalysts were studied as a means of lowering the reaction temperature. A lower reaction temperature would have the benefits of more rapid quenching as well as a more feasible commercial process due to savings realized in energy and material of construction costs. It was the goal of the project to identify promising routes from methane to higher hydrocarbons based on the pyrolysis of methane.

  10. Methane Clathrate Hydrate Prospecting

    NASA Technical Reports Server (NTRS)

    Duxbury, N.; Romanovsky, V.

    2003-01-01

    A method of prospecting for methane has been devised. The impetus for this method lies in the abundance of CH4 and the growing shortages of other fuels. The method is intended especially to enable identification of subpermafrost locations where significant amounts of methane are trapped in the form of methane gas hydrate (CH4(raised dot)6H2O). It has been estimated by the U.S. Geological Survey that the total CH4 resource in CH4(raised dot) 6H2O exceeds the energy content of all other fossil fuels (oil, coal, and natural gas from non-hydrate sources). Also, CH4(raised dot)6H2O is among the cleanest-burning fuels, and CH4 is the most efficient fuel because the carbon in CH4 is in its most reduced state. The method involves looking for a proxy for methane gas hydrate, by means of the combination of a thermal-analysis submethod and a field submethod that does not involve drilling. The absence of drilling makes this method easier and less expensive, in comparison with prior methods of prospecting for oil and natural gas. The proposed method would include thermoprospecting in combination with one more of the other non-drilling measurement techniques, which could include magneto-telluric sounding and/or a subsurface-electrical-resistivity technique. The method would exploit the fact that the electrical conductivity in the underlying thawed region is greater than that in the overlying permafrost.

  11. Volumetric Interpretation of Protein Adsorption: Ion-Exchange Adsorbent Capacity, Protein pI, and Interaction Energetics

    PubMed Central

    Noh, Hyeran; Yohe, Stefan; Vogler, Erwin A.

    2008-01-01

    Adsorption of lysozyme (Lys), human serum albumin (HSA), and immunoglobulin G (IgG) to anion- and cation-exchange resins is dominated by electrostatic interactions between protein and adsorbent. The solution-depletion method of measuring adsorption shows, however, that these proteins do not irreversibly adsorb to ion-exchange surfaces, even when the charge disparity between adsorbent and protein inferred from protein pI is large. Net-positively-charged Lys (pI = 11) and net-negatively-charged HSA (pI = 5.5) adsorb so strongly to sulfopropyl sepharose (SP; a negatively-charged, strong cation exchange resin, −0.22 mmol/mL exchange capacity) that both resist displacement by net-neutral IgG (pI = 7.0) in simultaneous adsorption-competition experiments. By contrast, IgG readily displaces both Lys and HSA adsorbed either to quarternary-ammonium sepharose (Q; a positively-charged, strong anion exchanger, + 0.22 mmol/mL exchange capacity) or octadecyl sepharose (ODS, a neutral hydrophobic resin, 0 mmol/mL exchange capacity). Thus it is concluded that adsorption results do not sensibly correlate with protein pI and that pI is actually a rather poor predictor of affinity for ion-exchange surfaces. Adsorption of Lys, HSA, and IgG to ion-exchange resins from stagnant solution leads to adsorbed multi-layers, into-or-onto which IgG adsorbs in adsorption-competition experiments. Comparison of adsorption to ion-exchange resins and neutral ODS leads to the conclusion that the apparent standard free-energy-of-adsorption ΔGadso of Lys, HSA, and IgG is not large in comparison to thermal energy due to energy-compensating interactions between water, protein, and ion-exchange surfaces that leaves a small net ΔGadso. Thus water is found to control protein adsorption to a full range of substratum types spanning hydrophobic (poorly water wettable) surfaces, hydrophilic surfaces bearing relatively-weak Lewis acid/base functionalities that wet with (hydrogen bond to) water but do not

  12. Insight into the adsorption of PPCPs by porous adsorbents: Effect of the properties of adsorbents and adsorbates.

    PubMed

    Zhu, Zengyin; Xie, Jiawen; Zhang, Mancheng; Zhou, Qing; Liu, Fuqiang

    2016-07-01

    Adsorption is an efficient method for removal of pharmaceuticals and personal care products (PPCPs). Magnetic resins are efficient adsorbents for water treatment and exhibit potential for PPCP removal. In this study, the magnetic hypercrosslinked resin Q100 was used for adsorption of PPCPs. The adsorption behavior of this resin was compared with those of two activated carbons, namely, Norit and F400D. Norit exhibited the fastest adsorption kinetics, followed by Q100. Norit featured a honeycomb shape and long-range ordered pore channels, which facilitated the diffusion of PPCPs. Moreover, the large average pore size of Q100 reduced diffusion resistance. The adsorbed amounts of 11 PPCPs on the three adsorbents increased with increasing adsorbate hydrophobicity. For Q100, a significant linear correlation was observed between the adsorption performance for PPCPs and hydrophobicity (logD value) of adsorbates (R(2) = 0.8951); as such, PPCPs with high logD values (>1.69) could be efficiently removed. Compared with those of Norit and F400D, the adsorption performance of Q100 was less affected by humic acid because of the dominant hydrophobic interaction. Furthermore, Q100 showed improved regeneration performance, which renders it promising for PPCP removal in practical applications. PMID:27131811

  13. Polybenzimidazole via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G. (Inventor)

    1994-01-01

    Di(hydroxyphenyl)benzimidazole monomers were prepared from phenyl-4-hydroxybenzoate and aromatic bis(o-diamine)s. These monomers were used in the synthesis of soluble polybenzimidazoles. The reaction involved the aromatic nucleophilic displacement of various di(hydroxyphenyl)benzimidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds in the presence of an alkali metal base. These polymers exhibited lower glass transition temperatures, improved solubility, and better compression moldability over their commercial counterparts.

  14. Methane capture from livestock manure.

    PubMed

    Tauseef, S M; Premalatha, M; Abbasi, Tasneem; Abbasi, S A

    2013-03-15

    It has been estimated that livestock manure contributes about 240 million metric tons of carbon dioxide equivalent of methane to the atmosphere and represents one of the biggest anthropogenic sources of methane. Considering that methane is the second biggest contributor to global warming after carbon dioxide, it is imperative that ways and means are developed to capture as much of the anthropogenic methane as possible. There is a major associated advantage of methane capture: its use as a source of energy which is comparable in 'cleanness' to natural gas. The present review dwells upon the traditional ways of methane capture used in India, China, and other developing countries for providing energy to the rural poor. It then reviews the present status of methane capture from livestock manure in developed countries and touches upon the prevalent trends.

  15. Future methane emissions from animals

    SciTech Connect

    Anastasi, C.; Simpson, V.J. )

    1993-04-20

    The authors project future methane emissions from animals to the year 2025. They review the present estimated sources of methane from enteric fermentation in animals. Ruminant animals produce the highest concentrations of methane. Methane is a byproduct of anaerobic breakdown of carbohydrates by microbes in the digestive tract of herbatious animals. In general the methane production depends on the variety of animal, the quality of the feed, and the feeding level. Since cattle, sheep, and buffalo account for roughly 91% of all animal methane emission, they only study these animals in detail. Results suggest a rise in methane production of roughly 1% per year averaged through 2025. Increasing levels are found to originate from developed countries even though the feedstock levels are lower.

  16. Stepwise morphological change of porous amorphous ice films observed through adsorption of methane

    NASA Astrophysics Data System (ADS)

    Horimoto, Noriko; Kato, Hiroyuki S.; Kawai, Maki

    2002-03-01

    Morphological change of amorphous ice films of D2O has been studied through adsorption of methane using thermal desorption spectroscopy (TDS) and infrared reflection absorption spectroscopy under ultrahigh vacuum. The investigated ice films were prepared under several different conditions; first, water (D2O) molecules are evaporated onto a Ru substrate at 25 K, and then subjected to an annealing process at various temperatures prior to methane deposition. On ice annealed at low temperatures, two desorption species of methane were observed in TDS: one was derived from methane adsorbed near the ice surface and the other was attributed to the desorption of methane encapsulated in ice during heating. Only the former species was observed when the annealing temperature exceeded 60 K. This indicates that reconstruction of ice occurs below 60 K, which inhibits the encapsulation of methane molecules from the amorphous ice. On the other hand, infrared spectra of ice covered with methane show that the micropores in ice start to collapse at ˜80 K, and ice becomes pore free at 120 K. We have found that the morphological change of amorphous ice induced by thermal relaxation takes place in a stepwise manner.

  17. Methane emissions from Alaska arctic tundra in response to climatic change

    SciTech Connect

    Livingston, G.P.; Morrissey, L.A.

    1992-03-01

    In situ observations of methane emissions from the Alaska North Slope in 1987 and 1989 provide insight into the environmental interactions regulating methane emissions and into the local- and regional-scale response of the arctic tundra to interannual environmental variability. Inferences regarding climate change are based on in situ measurements of methane emissions, regional landscape characterizations derived from Landsat Multispectral Scanner satellite data, and projected regional scale emissions based on observed interannual temperature differences and simulated changes in the spatial distribution of methane emissions. Results suggest that biogenic methane emissions from arctic tundra will be significantly perturbed by climatic change, leading to warmer summer soil temperatures and to vertical displacement of the regional water table. The effect of increased soil temperatures on methane emissions resulting from anaerobic decomposition in northern wetlands will be to both increase total emissions and to increase interannual and seasonal variability. The magnitude of these effects will be determined by those factors affecting the areal distribution of methane emission rates through regulation of the regional water table. At local scales, the observed 4.7 C increase in mid-summer soil temperatures between 1987 and 1989 resulted in a 3.2-fold increase in the rate of methane emissions from anaerobic soils.

  18. Size selective hydrophobic adsorbent for organic molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor); Hickey, Gregory S. (Inventor)

    1997-01-01

    The present invention relates to an adsorbent formed by the pyrolysis of a hydrophobic silica with a pore size greater than 5 .ANG., such as SILICALITE.TM., with a molecular sieving polymer precursor such as polyfurfuryl alcohol, polyacrylonitrile, polyvinylidene chloride, phenol-formaldehyde resin, polyvinylidene difluoride and mixtures thereof. Polyfurfuryl alcohol is the most preferred. The adsorbent produced by the pyrolysis has a silicon to carbon mole ratio of between about 10:1 and 1:3, and preferably about 2:1 to 1:2, most preferably 1:1. The pyrolysis is performed as a ramped temperature program between about 100.degree. and 800.degree. C., and preferably between about 100.degree. and 600.degree. C. The present invention also relates to a method for selectively adsorbing organic molecules having a molecular size (mean molecular diameter) of between about 3 and 6 .ANG. comprising contacting a vapor containing the small organic molecules to be adsorbed with the adsorbent composition of the present invention.

  19. Black Molecular Adsorber Coatings for Spaceflight Applications

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin Susan; Hasegawa, Mark Makoto; Straka, Sharon A.

    2014-01-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

  20. Black molecular adsorber coatings for spaceflight applications

    NASA Astrophysics Data System (ADS)

    Abraham, Nithin S.; Hasegawa, Mark M.; Straka, Sharon A.

    2014-09-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

  1. Structural relaxation of adlayers in the presence of adsorbate-induced reconstruction: C60/Cu(111)

    NASA Astrophysics Data System (ADS)

    Pai, Woei Wu; Hsu, Ching-Ling; Lin, M. C.; Lin, K. C.; Tang, T. B.

    2004-03-01

    We revisit submonolayer growth of C60 on Cu(111) by scanning tunneling microscopy (STM), with emphasis on the formation of higher-order commensurate metastable states. These phases show concomitant interfacial reconstruction, adlayer buckling, and adlayer rotation in order to match as closely as possible the 10.0 Å C60 nearest neighbor (NN) distance. Most interestingly, a clear correlation between the adlayer rotation angle and molecular contrast patterns is demonstrated. This is caused by the C60-induced reconstruction at preferred binding sites and adlayer buckling in adjustment to strain. Four contrast patterns, i.e., “disordered maze,” “linear-wall maze,” “p(√(7)×√(7)),” and “p(2×2),” with increasing C60 NN distances are categorized. In the most compressed phase, buckling is favored and it is analogous to the ground state of a strongly-coupled antiferromagnetic system on a triangular lattice with alike adlayer buckling and interfacial corrugation. In contrast, the molecular orderings in the other structures are mostly dictated by lateral displacements of C60 toward preferred reconstructive binding sites. These metastable phases thus illustrate structural relaxation of a molecular layer on an adsorbate-induced reconstructed substrate in different adsorbate-adsorbate and adsorbate-substrate interaction limits.

  2. Method for modifying trigger level for adsorber regeneration

    DOEpatents

    Ruth, Michael J.; Cunningham, Michael J.

    2010-05-25

    A method for modifying a NO.sub.x adsorber regeneration triggering variable. Engine operating conditions are monitored until the regeneration triggering variable is met. The adsorber is regenerated and the adsorbtion efficiency of the adsorber is subsequently determined. The regeneration triggering variable is modified to correspond with the decline in adsorber efficiency. The adsorber efficiency may be determined using an empirically predetermined set of values or by using a pair of oxygen sensors to determine the oxygen response delay across the sensors.

  3. Methane cycling. Nonequilibrium clumped isotope signals in microbial methane.

    PubMed

    Wang, David T; Gruen, Danielle S; Lollar, Barbara Sherwood; Hinrichs, Kai-Uwe; Stewart, Lucy C; Holden, James F; Hristov, Alexander N; Pohlman, John W; Morrill, Penny L; Könneke, Martin; Delwiche, Kyle B; Reeves, Eoghan P; Sutcliffe, Chelsea N; Ritter, Daniel J; Seewald, Jeffrey S; McIntosh, Jennifer C; Hemond, Harold F; Kubo, Michael D; Cardace, Dawn; Hoehler, Tori M; Ono, Shuhei

    2015-04-24

    Methane is a key component in the global carbon cycle, with a wide range of anthropogenic and natural sources. Although isotopic compositions of methane have traditionally aided source identification, the abundance of its multiply substituted "clumped" isotopologues (for example, (13)CH3D) has recently emerged as a proxy for determining methane-formation temperatures. However, the effect of biological processes on methane's clumped isotopologue signature is poorly constrained. We show that methanogenesis proceeding at relatively high rates in cattle, surface environments, and laboratory cultures exerts kinetic control on (13)CH3D abundances and results in anomalously elevated formation-temperature estimates. We demonstrate quantitatively that H2 availability accounts for this effect. Clumped methane thermometry can therefore provide constraints on the generation of methane in diverse settings, including continental serpentinization sites and ancient, deep groundwaters. PMID:25745067

  4. Project identification for methane reduction options

    SciTech Connect

    Kerr, T.

    1996-12-31

    This paper discusses efforts directed at reduction in emission of methane to the atmosphere. Methane is a potent greenhouse gas, which on a 20 year timeframe may present a similar problem to carbon dioxide. In addition, methane causes additional problems in the form of smog and its longer atmospheric lifetime. The author discusses strategies for reducing methane emission from several major sources. This includes landfill methane recovery, coalbed methane recovery, livestock methane reduction - in the form of ruminant methane reduction and manure methane recovery. The author presents examples of projects which have implemented these ideas, the economics of the projects, and additional gains which come from the projects.

  5. Colloidal metal oxide nanocrystal catalysis by sustained chemically driven ligand displacement

    NASA Astrophysics Data System (ADS)

    de Roo, Jonathan; van Driessche, Isabel; Martins, José C.; Hens, Zeger

    2016-05-01

    Surface chemistry is a key enabler for colloidal nanocrystal applications. In this respect, metal oxide nanocrystals (NCs) stand out from other NCs as carboxylic acid ligands adsorb on their surface by dissociation to carboxylates and protons, the latter proving essential in electron transfer reactions. Here, we show that this binding motif sets the stage for chemically driven ligand displacement where the binding of amines or alcohols to HfO2 NCs is promoted by the conversion of a bound carboxylic acid into a non-coordinating amide or ester. Furthermore, the sustained ligand displacement, following the addition of excess carboxylic acid, provides a catalytic pathway for ester formation, whereas the addition of esters leads to NC-catalysed transesterification. Because sustained, chemically driven ligand displacement leaves the NCs--including their surface composition--unchanged and preserves colloidal stability, metal oxide nanocrystals are thus turned into effective nanocatalysts that bypass the tradeoff between colloidal stability and catalytic activity.

  6. Removal of molecular adsorbates on gold nanoparticles using sodium borohydride in water.

    PubMed

    Ansar, Siyam M; Ameer, Fathima S; Hu, Wenfang; Zou, Shengli; Pittman, Charles U; Zhang, Dongmao

    2013-03-13

    The mechanism of sodium borohydride removal of organothiols from gold nanoparticles (AuNPs) was studied using an experimental investigation and computational modeling. Organothiols and other AuNP surface adsorbates such as thiophene, adenine, rhodamine, small anions (Br(-) and I(-)), and a polymer (PVP, poly(N-vinylpyrrolidone)) can all be rapidly and completely removed from the AuNP surfaces. A computational study showed that hydride derived from sodium borohydride has a higher binding affinity to AuNPs than organothiols. Thus, it can displace organothiols and all the other adsorbates tested from AuNPs. Sodium borohydride may be used as a hazard-free, general-purpose detergent that should find utility in a variety of AuNP applications including catalysis, biosensing, surface enhanced Raman spectroscopy, and AuNP recycle and reuse.

  7. Methane from acetate.

    PubMed

    Ferry, J G

    1992-09-01

    The general features are known for the pathway by which most methane is produced in nature. All acetate-utilizing methanogenic microorganisms contain CODH which catalyzes the cleavage of acetyl-CoA; however, the pathway differs from all other acetate-utilizing anaerobes in that the methyl group is reduced to methane with electrons derived from oxidation of the carbonyl group of acetyl-CoA to CO2. The current understanding of the methanogenic fermentation of acetate provides impressions of nature's novel solutions to problems of methyl transfer, electron transport, and energy conservation. The pathway is now at a level of understanding that will permit productive investigations of these and other interesting questions in the near future. PMID:1512186

  8. The case for character displacement in plants

    PubMed Central

    Beans, Carolyn M

    2014-01-01

    The evidence for character displacement as a widespread response to competition is now building. This progress is largely the result of the establishment of rigorous criteria for demonstrating character displacement in the animal literature. There are, however, relatively few well-supported examples of character displacement in plants. This review explores the potential for character displacement in plants by addressing the following questions: (1) Why aren't examples of character displacement in plants more common? (2) What are the requirements for character displacement to occur and how do plant populations meet those requirements? (3) What are the criteria for testing the pattern and process of character displacement and what methods can and have been used to address these criteria in the plant literature? (4) What are some additional approaches for studying character displacement in plants? While more research is needed, the few plant systems in which character displacement hypotheses have been rigorously tested suggest that character displacement may play a role in shaping plant communities. Plants are especially amenable to character displacement studies because of the experimental ease with which they can be used in common gardens, selection analyses, and breeding designs. A deeper investigation of character displacement in plants is critical for a more complete understanding of the ecological and evolutionary processes that permit the coexistence of plant species. PMID:24683467

  9. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Engine displacement. 205.153 Section... TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a) Engine displacement must be calculated using nominal engine values and rounded to the nearest whole cubic...

  10. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Engine displacement. 205.153 Section... TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a) Engine displacement must be calculated using nominal engine values and rounded to the nearest whole cubic...

  11. 25 CFR 700.59 - Displaced person.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 2 2010-04-01 2010-04-01 false Displaced person. 700.59 Section 700.59 Indians THE OFFICE OF NAVAJO AND HOPI INDIAN RELOCATION COMMISSION OPERATIONS AND RELOCATION PROCEDURES General Policies and Instructions Definitions § 700.59 Displaced person. Displaced person means a member of the Hopi Tribe residing within the area partitioned...

  12. 25 CFR 700.59 - Displaced person.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 25 Indians 2 2013-04-01 2013-04-01 false Displaced person. 700.59 Section 700.59 Indians THE OFFICE OF NAVAJO AND HOPI INDIAN RELOCATION COMMISSION OPERATIONS AND RELOCATION PROCEDURES General Policies and Instructions Definitions § 700.59 Displaced person. Displaced person means a member of the Hopi Tribe residing within the area partitioned...

  13. 25 CFR 700.59 - Displaced person.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 2 2011-04-01 2011-04-01 false Displaced person. 700.59 Section 700.59 Indians THE OFFICE OF NAVAJO AND HOPI INDIAN RELOCATION COMMISSION OPERATIONS AND RELOCATION PROCEDURES General Policies and Instructions Definitions § 700.59 Displaced person. Displaced person means a member of the Hopi Tribe residing within the area partitioned...

  14. 25 CFR 700.59 - Displaced person.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 25 Indians 2 2014-04-01 2014-04-01 false Displaced person. 700.59 Section 700.59 Indians THE OFFICE OF NAVAJO AND HOPI INDIAN RELOCATION COMMISSION OPERATIONS AND RELOCATION PROCEDURES General Policies and Instructions Definitions § 700.59 Displaced person. Displaced person means a member of the Hopi Tribe residing within the area partitioned...

  15. 25 CFR 700.59 - Displaced person.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 25 Indians 2 2012-04-01 2012-04-01 false Displaced person. 700.59 Section 700.59 Indians THE OFFICE OF NAVAJO AND HOPI INDIAN RELOCATION COMMISSION OPERATIONS AND RELOCATION PROCEDURES General Policies and Instructions Definitions § 700.59 Displaced person. Displaced person means a member of the Hopi Tribe residing within the area partitioned...

  16. The case for character displacement in plants.

    PubMed

    Beans, Carolyn M

    2014-03-01

    The evidence for character displacement as a widespread response to competition is now building. This progress is largely the result of the establishment of rigorous criteria for demonstrating character displacement in the animal literature. There are, however, relatively few well-supported examples of character displacement in plants. This review explores the potential for character displacement in plants by addressing the following questions: (1) Why aren't examples of character displacement in plants more common? (2) What are the requirements for character displacement to occur and how do plant populations meet those requirements? (3) What are the criteria for testing the pattern and process of character displacement and what methods can and have been used to address these criteria in the plant literature? (4) What are some additional approaches for studying character displacement in plants? While more research is needed, the few plant systems in which character displacement hypotheses have been rigorously tested suggest that character displacement may play a role in shaping plant communities. Plants are especially amenable to character displacement studies because of the experimental ease with which they can be used in common gardens, selection analyses, and breeding designs. A deeper investigation of character displacement in plants is critical for a more complete understanding of the ecological and evolutionary processes that permit the coexistence of plant species.

  17. Displacement Compensation of Temperature Probe Data

    NASA Technical Reports Server (NTRS)

    Welch, Christopher S.; Hubert, James A.; Barber, Patrick G.

    1996-01-01

    Analysis of temperature data from a probe in a vertical Bridgman furnace growing germanium crystals revealed a displacement of the temperature profile due to conduction error. A theoretical analysis shows that the displacement compensation is independent of local temperature gradient. A displacement compensation value should become a standard characteristic of temperature probes used for temperature profile measurements.

  18. A displaced-solvent functional analysis of model hydrophobic enclosures

    PubMed Central

    Abel, Robert; Wang, Lingle; Friesner, Richard A.; Berne, B. J.

    2010-01-01

    Calculation of protein-ligand binding affinities continues to be a hotbed of research. Although many techniques for computing protein-ligand binding affinities have been introduced--ranging from computationally very expensive approaches, such as free energy perturbation (FEP) theory; to more approximate techniques, such as empirically derived scoring functions, which, although computationally efficient, lack a clear theoretical basis--there remains pressing need for more robust approaches. A recently introduced technique, the displaced-solvent functional (DSF) method, was developed to bridge the gap between the high accuracy of FEP and the computational efficiency of empirically derived scoring functions. In order to develop a set of reference data to test the DSF theory for calculating absolute protein-ligand binding affinities, we have pursued FEP theory calculations of the binding free energies of a methane ligand with 13 different model hydrophobic enclosures of varying hydrophobicity. The binding free energies of the methane ligand with the various hydrophobic enclosures were then recomputed by DSF theory and compared with the FEP reference data. We find that the DSF theory, which relies on no empirically tuned parameters, shows excellent quantitative agreement with the FEP. We also explored the ability of buried solvent accessible surface area and buried molecular surface area models to describe the relevant physics, and find the buried molecular surface area model to offer superior performance over this dataset. PMID:21135914

  19. Ab initio modelling of methane hydrate thermophysical properties.

    PubMed

    Jendi, Z M; Servio, P; Rey, A D

    2016-04-21

    The key thermophysical properties of methane hydrate were determined using ab initio modelling. Using density functional theory, the second-order elastic constants, heat capacity, compressibility, and thermal expansion coefficient were calculated. A wide and relevant range of pressure-temperature conditions were considered, and the structures were assessed for stability using the mean square displacement and radial distribution functions. Methane hydrate was found to be elastically isotropic with a linear dependence of the bulk modulus on pressure. Equally significant, multi-body interactions were found to be important in hydrates, and water-water interactions appear to strongly influence compressibility like in ice Ih. While the heat capacity of hydrate was found to be higher than that of ice, the thermal expansion coefficient was significantly lower, most likely due to the lower rigidity of hydrates. The mean square displacement gave important insight into stability, heat capacity, and elastic moduli, and the radial distribution functions further confirmed stability. The presented results provide a much needed atomistic thermoelastic characterization of methane hydrates and are essential input for the large-scale applications of hydrate detection and production. PMID:27019976

  20. Displaced Children: The Psychological Implications.

    PubMed

    Joshi, Paramjit T; Fayyad, John A

    2015-10-01

    Millions of people across the world have been displaced or live in exile and/or as refugees largely as a consequence of wars, acts of terrorism, and catastrophic natural disasters. There are serious psychological consequences as a result of these extremely difficult life circumstances. Adults often can express their needs and have them be heard, whereas children are unable to do so. The children may be provided food, shelter, and clothing and have their medical needs attended to, but their emotional and psychological needs go unrecognized and unmet, with dire and monumental long-term consequences. PMID:26346385

  1. Displacement Current and Surface Flashover

    SciTech Connect

    harris, J R; Caporaso, G J; Blackfield, D; Chen, Y J

    2007-07-17

    High-voltage vacuum insulator failure is generally due to surface flashover rather than insulator bulk breakdown. Vacuum surface flashover is widely believed to be initiated by a secondary electron emission avalanche along the vacuum-insulator interface. This process requires a physical mechanism to cause secondary electrons emitted from the insulator surface to return to that surface. Here, we show that when an insulator is subjected to a fast high-voltage pulse, the magnetic field due to displacement current through the insulator can provide this mechanism. This indicates the importance of the voltage pulse shape, especially the rise time, in the flashover initiation process.

  2. Coal Bed Methane Primer

    SciTech Connect

    Dan Arthur; Bruce Langhus; Jon Seekins

    2005-05-25

    During the second half of the 1990's Coal Bed Methane (CBM) production increased dramatically nationwide to represent a significant new source of income and natural gas for many independent and established producers. Matching these soaring production rates during this period was a heightened public awareness of environmental concerns. These concerns left unexplained and under-addressed have created a significant growth in public involvement generating literally thousands of unfocused project comments for various regional NEPA efforts resulting in the delayed development of public and fee lands. The accelerating interest in CBM development coupled to the growth in public involvement has prompted the conceptualization of this project for the development of a CBM Primer. The Primer is designed to serve as a summary document, which introduces and encapsulates information pertinent to the development of Coal Bed Methane (CBM), including focused discussions of coal deposits, methane as a natural formed gas, split mineral estates, development techniques, operational issues, producing methods, applicable regulatory frameworks, land and resource management, mitigation measures, preparation of project plans, data availability, Indian Trust issues and relevant environmental technologies. An important aspect of gaining access to federal, state, tribal, or fee lands involves education of a broad array of stakeholders, including land and mineral owners, regulators, conservationists, tribal governments, special interest groups, and numerous others that could be impacted by the development of coal bed methane. Perhaps the most crucial aspect of successfully developing CBM resources is stakeholder education. Currently, an inconsistent picture of CBM exists. There is a significant lack of understanding on the parts of nearly all stakeholders, including industry, government, special interest groups, and land owners. It is envisioned the Primer would being used by a variety of

  3. Methane ocean on Titan?

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    There was an impressive list of names on a recent scientific communication that argues for the existence on Titan of an ocean of liquid methane (CH4) perhaps several hundred meters deep. C. Sagan and S. Dermott with helpful comments by S. Oter, S. Ostro, S. Peale, C. Yoder, W. Thompson, S. Squyres, G. Pettengill, P. Gierasch, and B. Khare speculate that such a methanic ocean, with its Saturnian tides and its tholinian floor, should exist all over Titan's surface; it should unless, they conclude, there is the ‘distracting coincidence [that] … the position of the surface of Titan [is] … near the liquidus in the CH4phase diagram [and, consequently, there is] …almost no methane ocean at all’ (Nature, 300, 731, 1982).We know very little about Titan and its surface; the way of checking into Sagan and Dermott's ideas appears to rest on the interpretation of radar reflectivity data. Preliminary attempts to obtain radar data were made in 1979 with the 305-m Arecibo telescope, but only broad limits resulted. The next opportunity for a measurement at Arecibo comes in the 1990's. Of course, the ideal circumstance would be to send spacecraft equipped with a radar reflectometer for a Titan flyby.

  4. Oxidized dahlia-like carbon nanohorns: adsorption of argon, methane and nitrogen

    NASA Astrophysics Data System (ADS)

    Krungleviciute, Vaiva; Migone, Aldo; Yudasaka, Masako; Iijima, Sumio

    2010-03-01

    Different types of nanohorns, and nanohorn aggregates, can be produced depending on the parameters used during their production. We used a sample consisting mainly of dahlia-like nanohorn aggregates. In the dahlia-like aggregates the individual nanohorns are aligned radially, forming a sphere, with their individual ends protruding from the outer surface of the spherule. Our sample was oxidized by flowing pure oxygen. This treatment opened entry ports into the spaces at the interior of the individual nanohorns. We measured volumetric adsorption isotherms at 77.3 K with argon, methane, and nitrogen. For argon and methane two distinct substeps are present in the adsorption data; the steps for each of these two gases are comparable in size. For nitrogen there is a clear step present at lower adsorbent loadings, and a more gradual growth in the amount adsorbed as saturation is approached.

  5. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, John

    1995-01-01

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically.

  6. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, John

    1999-01-01

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically.

  7. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, J.

    1995-05-30

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically. 29 figs.

  8. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, J.

    1999-04-06

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically. 23 figs.

  9. Effect of carbon dioxide and nitrogen on the diffusivity of methane confined in nano-porous carbon aerogel

    SciTech Connect

    Mavila Chathoth, Suresh; He, Lilin; Mamontov, Eugene; Melnichenko, Yuri B

    2012-01-01

    The microscopic diffusivity of methane (CH{sub 4}) confined in nano-porous carbon aerogel was investigated as a function of added carbon dioxide (CO{sub 2}) and nitrogen (N{sub 2}) pressure using quasi-elastic neutron scattering (QENS). In the range of the external pressure of 1-2.5 MPa, the self-diffusivity of methane was found to increase with CO{sub 2} pressure and remain practically unchanged in the N{sub 2} environment. Increasing mobility of methane with CO{sub 2} pressure suggests that the adsorbed CH4 molecules become gradually replaced by CO{sub 2} on the surface of carbon aerogel pores, whereas the presence of N{sub 2} does not induce the replacement. The molecular mobility of the methane, with or without added carbon dioxide and nitrogen, is described by the unrestricted diffusion model, which is characteristic of methane compressed in small pores. On the other hand, both nitrogen and carbon dioxide molecules in carbon aerogel, when studied alone, with no methane present, follow a jump diffusion process, characteristic of the molecular mobility in the densified adsorbed layers on the surface of the aerogel pores.

  10. Methane/nitrogen separation process

    DOEpatents

    Baker, R.W.; Lokhandwala, K.A.; Pinnau, I.; Segelke, S.

    1997-09-23

    A membrane separation process is described for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. The authors have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen. 11 figs.

  11. Methane/nitrogen separation process

    DOEpatents

    Baker, Richard W.; Lokhandwala, Kaaeid A.; Pinnau, Ingo; Segelke, Scott

    1997-01-01

    A membrane separation process for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. We have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen.

  12. On methane pyrolysis special applications

    NASA Astrophysics Data System (ADS)

    Toncu, D. C.; Toncu, G.; Soleimani, S.

    2015-11-01

    Methane pyrolysis represents one of the most important processes in industrial use, with applications rising from the chemical and petrochemical industry, combustion, materials and protective coatings. Despite the intense research, experimental data lack kinetic aspects, and the thermodynamics involved often leads to inaccurate results when applied to various systems. Carrying out a comparative analysis of several available data on methane pyrolysis, the paper aims to study the phenomenon of methane pyrolysis under different environments (combustion and plasma), concluding on the most possible reaction pathways involved in many of its applications. Computer simulation using different database underlines the conclusion, helping to the understanding of methane pyrolysis importance in future technologies.

  13. Redefining the isotopic boundaries of biogenic methane: Methane from endoevaporites

    NASA Astrophysics Data System (ADS)

    Tazaz, Amanda M.; Bebout, Brad M.; Kelley, Cheryl A.; Poole, Jennifer; Chanton, Jeffrey P.

    2013-06-01

    The recent reports of methane in the atmosphere of Mars, as well as the findings of hypersaline paleoenvironments on that planet, have underscored the need to evaluate the importance of biological (as opposed to geological) trace gas production and consumption, particularly in hypersaline environments. Methane in the atmosphere of Mars may be an indication of extant life, but it may also be a consequence of geologic activity and/or the thermal alteration of ancient organic matter. On Earth these methane sources can be distinguished using stable isotopic analyses and the ratio of methane (C1) to C2 and C3 alkanes present in the gas source (C1/(C2 + C3)). We report here that methane produced in hypersaline environments on Earth has an isotopic composition and alkane content outside the values presently considered to indicate a biogenic origin. Methane-rich bubbles released from sub-aqueous substrates contained δ13CCH4 and δ2HCH4 values ranging from -65‰ to -35‰ and -350‰ to -140‰ respectively. Higher salinity endoevaporites yielded what would be considered non-biogenic methane based upon stable isotopic and alkane content, however incubation of crustal and algal mat samples resulted in methane production with similar isotopic values. Radiocarbon analysis indicated that the production of the methane was from recently fixed carbon. An extension of the isotopic boundaries of biogenic methane is necessary in order to avoid the possibility of false negatives returned from measurements of methane on Mars and other planetary bodies.

  14. Diffusion in confinement: kinetic simulations of self- and collective diffusion behavior of adsorbed gases

    SciTech Connect

    Abouelnasr, MKF; Smit, B

    2012-01-01

    The self- and collective-diffusion behaviors of adsorbed methane, helium, and isobutane in zeolite frameworks LTA, MFI, AFI, and SAS were examined at various concentrations using a range of molecular simulation techniques including Molecular Dynamics (MD), Monte Carlo (MC), Bennett-Chandler (BC), and kinetic Monte Carlo (kMC). This paper has three main results. (1) A novel model for the process of adsorbate movement between two large cages was created, allowing the formulation of a mixing rule for the re-crossing coefficient between two cages of unequal loading. The predictions from this mixing rule were found to agree quantitatively with explicit simulations. (2) A new approach to the dynamically corrected Transition State Theory method to analytically calculate self-diffusion properties was developed, explicitly accounting for nanoscale fluctuations in concentration. This approach was demonstrated to quantitatively agree with previous methods, but is uniquely suited to be adapted to a kMC simulation that can simulate the collective-diffusion behavior. (3) While at low and moderate loadings the self- and collective-diffusion behaviors in LTA are observed to coincide, at higher concentrations they diverge. A change in the adsorbate packing scheme was shown to cause this divergence, a trait which is replicated in a kMC simulation that explicitly models this behavior. These phenomena were further investigated for isobutane in zeolite MFI, where MD results showed a separation in self- and collective-diffusion behavior that was reproduced with kMC simulations.

  15. The biogeochemical cycle of the adsorbed template. II - Selective adsorption of mononucleotides on adsorbed polynucleotide templates

    NASA Technical Reports Server (NTRS)

    Lazard, Daniel; Lahav, Noam; Orenberg, James B.

    1988-01-01

    Experimental results are presented for the verification of the specific interaction step of the 'adsorbed template' biogeochemical cycle, a simple model for a primitive prebiotic replication system. The experimental system consisted of gypsum as the mineral to which an oligonucleotide template attaches (Poly-C or Poly-U) and (5-prime)-AMP, (5-prime)-GMP, (5-prime)-CMP and (5-prime)-UMP as the interacting biomonomers. When Poly-C or Poly-U were used as adsorbed templates, (5-prime)-GMP and (5-prime)-AMP, respectively, were observed to be the most strongly adsorbed species.

  16. Radon emanation from radium specific adsorbents.

    PubMed

    Alabdula'aly, Abdulrahman I; Maghrawy, Hamed B

    2010-01-01

    Pilot studies were undertaken to quantify the total activity of radon that is eluted following no-flow periods from several Ra-226 adsorbents loaded to near exhaustion. The adsorbents studied included two types of barium sulphate impregnated alumina (ABA-8000 and F-1) and Dowex MSC-1 resin treated by either barium hydroxide or barium chloride. In parallel, radium loaded plain activated aluminas and Dowex MSC-1 resin were similarly investigated. The results revealed that radon was quantitatively eluted during the first few bed volumes of column operation after no-flow periods. Although similar radon elution profiles were obtained, the position of the radon peak was found to vary and depended on the adsorbent type. Radon levels up to 24 and 14 kBq dm(-3) were measured after a rest period of 72h from radium exhausted Dowex MSC-1 treated with barium chloride and F-1 impregnated alumina with barium sulphate, respectively. The eluted radon values measured experimentally were compared to those calculated theoretically from accumulated radium quantities for the different media. For plain adsorbents, an agreement better than 10% was obtained. For treated resin-types a consistency within 30% but for impregnated alumina-types high discrepancy between respective values were obtained.

  17. Unoccupied electronic states in adsorbate systems

    NASA Astrophysics Data System (ADS)

    Bertel, E.

    1991-11-01

    Experimental work on unoccupied electronic states in adsorbate systems on metallic substrates is reviewed with emphasis on recent developments. The first part is devoted to molecular adsorbates. Weakly chemisorbed hydrocarbons are briefly discussed. An exhaustive inverse photoemission (IPE) study of the CO bond to the transition metals Ni, Pb, and Pt is presented. Adsorbed NO is taken as an example to demonstrate the persisting discrepancies in the interpretation of IPE spectra. Atomic adsorbates are discussed in the second part. The quantum well state model is applied to interpret the surface states in reconstructing and non-reconstructing adsorption systems of alkali metals and hydrogen. A recent controversy on the unoccupied electronic states of the Cu(110)/O p(2×1) surface is critically reviewed. The quantum well state model is then compared to tight binding and local-density-functional calculations of the unoccupied bands and the deficiencies of the various approaches are pointed out. Finally, the relation between the surface state model and more chemically oriented models of surface bonding is briefly discussed.

  18. Continuum elastic theory of adsorbate vibrational relaxation

    NASA Astrophysics Data System (ADS)

    Lewis, Steven P.; Pykhtin, M. V.; Mele, E. J.; Rappe, Andrew M.

    1998-01-01

    An analytical theory is presented for the damping of low-frequency adsorbate vibrations via resonant coupling to the substrate phonons. The system is treated classically, with the substrate modeled as a semi-infinite elastic continuum and the adsorbate overlayer modeled as an array of point masses connected to the surface by harmonic springs. The theory provides a simple expression for the relaxation rate in terms of fundamental parameters of the system: γ=mω¯02/AcρcT, where m is the adsorbate mass, ω¯0 is the measured frequency, Ac is the overlayer unit-cell area, and ρ and cT are the substrate mass density and transverse speed of sound, respectively. This expression is strongly coverage dependent, and predicts relaxation rates in excellent quantitative agreement with available experiments. For a half-monolayer of carbon monoxide on the copper (100) surface, the predicted damping rate of in-plane frustrated translations is 0.50×1012s-1, as compared to the experimental value of (0.43±0.07)×1012s-1. Furthermore it is shown that, for all coverages presently accessible to experiment, adsorbate motions exhibit collective effects which cannot be treated as stemming from isolated oscillators.

  19. Pore Size Effect on Methane Adsorption in Mesoporous Silica Materials Studied by Small-Angle Neutron Scattering.

    PubMed

    Chiang, Wei-Shan; Fratini, Emiliano; Baglioni, Piero; Chen, Jin-Hong; Liu, Yun

    2016-09-01

    Methane adsorption in model mesoporous silica materials with the size range characteristic of shale is studied by small-angle neutron scattering (SANS). Size effect on the temperature-dependent gas adsorption at methane pressure about 100 kPa is investigated by SANS using MCM-41 and SBA-15 as adsorbents. Above the gas-liquid condensation temperature, the thickness of the adsorption layer is found to be roughly constant as a function of the temperature. Moreover, the gas adsorption properties, such as the adsorbed layer thickness and the specific amount of adsorbed gas, have little dependence on the pore size being studied, i.e., pore radius of 16.5 and 34.1 Å, but are mainly affected by the roughness of the pore surfaces. Hence, the surface properties of the pore wall are more dominant than the pore size in determining the methane gas adsorption of pores at the nanometer size range. Not surprisingly, the gas-liquid condensation temperature is observed to be sensitive to pore size and shifts to higher temperature when the pore size is smaller. Below the gas-liquid condensation temperature, even though the majority of gas adsorption experiments/simulations have assumed the density of confined liquid to be the same as the bulk density, the measured methane mass density in our samples is found to be appreciably smaller than the bulk methane density regardless of the pore sizes studied here. The mass density of liquid/solid methane in pores with different sizes shows different temperature dependence below the condensation temperature. With decreasing temperature, the methane density in larger pores (SBA-15) abruptly increases at approximately 65 K and then plateaus. In contrast, the density in smaller pores (MCM-41) monotonically increases with decreasing temperature before reaching a plateau at approximately 30 K.

  20. Pore Size Effect on Methane Adsorption in Mesoporous Silica Materials Studied by Small-Angle Neutron Scattering.

    PubMed

    Chiang, Wei-Shan; Fratini, Emiliano; Baglioni, Piero; Chen, Jin-Hong; Liu, Yun

    2016-09-01

    Methane adsorption in model mesoporous silica materials with the size range characteristic of shale is studied by small-angle neutron scattering (SANS). Size effect on the temperature-dependent gas adsorption at methane pressure about 100 kPa is investigated by SANS using MCM-41 and SBA-15 as adsorbents. Above the gas-liquid condensation temperature, the thickness of the adsorption layer is found to be roughly constant as a function of the temperature. Moreover, the gas adsorption properties, such as the adsorbed layer thickness and the specific amount of adsorbed gas, have little dependence on the pore size being studied, i.e., pore radius of 16.5 and 34.1 Å, but are mainly affected by the roughness of the pore surfaces. Hence, the surface properties of the pore wall are more dominant than the pore size in determining the methane gas adsorption of pores at the nanometer size range. Not surprisingly, the gas-liquid condensation temperature is observed to be sensitive to pore size and shifts to higher temperature when the pore size is smaller. Below the gas-liquid condensation temperature, even though the majority of gas adsorption experiments/simulations have assumed the density of confined liquid to be the same as the bulk density, the measured methane mass density in our samples is found to be appreciably smaller than the bulk methane density regardless of the pore sizes studied here. The mass density of liquid/solid methane in pores with different sizes shows different temperature dependence below the condensation temperature. With decreasing temperature, the methane density in larger pores (SBA-15) abruptly increases at approximately 65 K and then plateaus. In contrast, the density in smaller pores (MCM-41) monotonically increases with decreasing temperature before reaching a plateau at approximately 30 K. PMID:27512895

  1. A theoretical model to predict both horizontal displacement and vertical displacement for electromagnetic induction-based deep displacement sensors.

    PubMed

    Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong

    2012-01-01

    Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type) to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA) to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA) has been proposed to quantitatively depict II-type sensors' mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors' monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency.

  2. A Theoretical Model to Predict Both Horizontal Displacement and Vertical Displacement for Electromagnetic Induction-Based Deep Displacement Sensors

    PubMed Central

    Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong

    2012-01-01

    Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type) to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA) to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA) has been proposed to quantitatively depict II-type sensors’ mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors’ monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency. PMID:22368467

  3. Compact, Lightweight Adsorber and Sabatier Reactor for CO2 Capture and Reduction for Consumable and Propellant Production

    NASA Technical Reports Server (NTRS)

    Junaedi, Christian; Hawley, Kyle; Walsh, Dennis; Roychoudhury, Subir; Busby, Stacy A.; Abney, Morgan B.; Perry, Jay L.; Knox, James C.

    2012-01-01

    The utilization of CO2 to produce (or recycle) life support consumables, such as O2 and H2O, and to generate propellant fuels is an important aspect of NASA's concept for future, long duration planetary exploration. One potential approach is to capture and use CO2 from the Martian atmosphere to generate the consumables and propellant fuels. Precision Combustion, Inc. (PCI), with support from NASA, continues to develop its regenerable adsorber technology for capturing CO2 from gaseous atmospheres (for cabin atmosphere revitalization and in-situ resource utilization applications) and its Sabatier reactor for converting CO2 to methane and water. Both technologies are based on PCI's Microlith(R) substrates and have been demonstrated to reduce size, weight, and power consumption during CO2 capture and methanation process. For adsorber applications, the Microlith substrates offer a unique resistive heating capability that shows potential for short regeneration time and reduced power requirements compared to conventional systems. For the Sabatier applications, the combination of the Microlith substrates and durable catalyst coating permits efficient CO2 methanation that favors high reactant conversion, high selectivity, and durability. Results from performance testing at various operating conditions will be presented. An effort to optimize the Sabatier reactor and to develop a bench-top Sabatier Development Unit (SDU) will be discussed.

  4. Consumption of atmospheric methane by tundra soils

    NASA Technical Reports Server (NTRS)

    Whalen, S. C.; Reeburgh, W. S.

    1990-01-01

    The results of field and laboratory experiments on methane consumption by tundra soils are reported. For methane concentrations ranging from below to well above ambient, moist soils are found to consume methane rapidly; in nonwaterlogged soils, equilibration with atmospheric methane is fast relative to microbial oxidation. It is concluded that lowering of the water table in tundra as a resulting from a warmer, drier climate will decrease methane fluxes and could cause these areas to provide negative feedback for atmospheric methane.

  5. Development and Testing of Molecular Adsorber Coatings

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin; Hasegawa, Mark; Straka, Sharon

    2012-01-01

    The effect of on-orbit molecular contamination has the potential to degrade the performance of spaceflight hardware and diminish the lifetime of the spacecraft. For example, sensitive surfaces, such as optical surfaces, electronics, detectors, and thermal control surfaces, are vulnerable to the damaging effects of contamination from outgassed materials. The current solution to protect these surfaces is through the use of zeolite coated ceramic adsorber pucks. However, these pucks and its additional complex mounting hardware requirements result in several disadvantages, such as size, weight, and cost related concerns, that impact the spacecraft design and the integration and test schedule. As a result, a new innovative molecular adsorber coating was developed as a sprayable alternative to mitigate the risk of on-orbit molecular contamination. In this study, the formulation for molecular adsorber coatings was optimized using various binders, pigment treatment methods, binder to pigment ratios, thicknesses, and spray application techniques. The formulations that passed coating adhesion and vacuum thermal cycling tests were further tested for its adsorptive capacity. Accelerated molecular capacitance tests were performed in an innovatively designed multi-unit system containing idealized contaminant sources. This novel system significantly increased the productivity of the testing phase for the various formulations that were developed. Work performed during the development and testing phases has demonstrated successful application of molecular adsorber coatings onto metallic substrates, as well as, very promising results for the adhesion performance and the molecular capacitance of the coating. Continued testing will assist in the qualification of molecular adsorber coatings for use on future contamination sensitive spaceflight missions.

  6. Computer simulations of adsorption and diffusion for binary mixtures of methane and hydrogen in titanosilicates.

    PubMed

    Mitchell, Martha C; Gallo, Marco; Nenoff, Tina M

    2004-07-22

    Equilibrium molecular dynamics (MD) simulations of equimolar mixtures of hydrogen and methane were performed in three different titanosilicates: naturally occurring zorite and two synthetic titanosilicates, ETS-4 and ETS-10. In addition, single-component MD simulations and adsorption isotherms generated using grand canonical Monte Carlo simulations were performed to support the mixture simulations. The goal of this study was to determine the best membrane material to carry out hydrogen/methane separations. ETS-10 has a three-dimensional pore network. ETS-4 and zorite have two-dimensional pore networks. The simulations carried out in this study show that the increased porosity of ETS-10 results in self-diffusion coefficients for both hydrogen and methane that are higher in ETS-10 than in either ETS-4 or zorite. Methane only showed appreciable displacement in ETS-10. The ability of the methane molecules to move in all three directions in ETS-10 was demonstrated by the high degree of isotropy shown in the values of the x, y, and z components of the self-diffusion coefficient for methane in ETS-10. From our simulations we conclude that ETS-10 would be better suited for fast industrial separations of hydrogen and methane. However, the separation would not result in a pure hydrogen stream. In contrast, ETS-4 and zorite would act as true molecular sieves for separations of hydrogen and methane, as the methane would not move through membranes made of these materials. This was indicated by the near-zero self-diffusion coefficient of methane in ETS-4 and zorite. PMID:15260743

  7. Microstructure-Dependent Gas Adsorption: Accurate Predictions of Methane Uptake in Nanoporous Carbons

    SciTech Connect

    Ihm, Yungok; Cooper, Valentino R; Gallego, Nidia C; Contescu, Cristian I; Morris, James R

    2014-01-01

    We demonstrate a successful, efficient framework for predicting gas adsorption properties in real materials based on first-principles calculations, with a specific comparison of experiment and theory for methane adsorption in activated carbons. These carbon materials have different pore size distributions, leading to a variety of uptake characteristics. Utilizing these distributions, we accurately predict experimental uptakes and heats of adsorption without empirical potentials or lengthy simulations. We demonstrate that materials with smaller pores have higher heats of adsorption, leading to a higher gas density in these pores. This pore-size dependence must be accounted for, in order to predict and understand the adsorption behavior. The theoretical approach combines: (1) ab initio calculations with a van der Waals density functional to determine adsorbent-adsorbate interactions, and (2) a thermodynamic method that predicts equilibrium adsorption densities by directly incorporating the calculated potential energy surface in a slit pore model. The predicted uptake at P=20 bar and T=298 K is in excellent agreement for all five activated carbon materials used. This approach uses only the pore-size distribution as an input, with no fitting parameters or empirical adsorbent-adsorbate interactions, and thus can be easily applied to other adsorbent-adsorbate combinations.

  8. Sorption of methane, ethane, propane, butane, carbon dioxide, and nitrogen on kerogen

    NASA Astrophysics Data System (ADS)

    Pribylov, A. A.; Skibitskaya, N. A.; Zekel', L. A.

    2014-06-01

    Sorption isotherms of nitrogen, methane (in the pressure range of 0.1-40 MPa), ethane (0.1-3.7MPa), propane (0.01-1 MPa), butane (0.01-0.2 MPa), and carbon dioxide (0.1-6 MPa) are measured on two adsorbents with kerogen contents of 16 and 75% at temperatures of 303, 323, 343 K. Adsorption volumes are calculated for all adsorption systems using two independent methods. The BET technique is used to determine the surface area values of the two adsorbents on the basis of sorption data for ethane, propane, butane, and carbon dioxide. The initial and isosteric adheat of sorption values are calculated on the basis of sorption isotherms of ethane, propane, butane, carbon dioxide measured at three temperatures. It is found from comparing the dependences of isosteric heat of sorption on the two adsorbents that molecules of the above gases diffuse into its bulk (adsorbent 2) in addition to sorbing on the outside surface formed by kerogen molecules, while sorption of the same gases on the rock (adsorbent 1) is similar to sorption on a smooth hard adsorbent surface.

  9. Methane emissions from canopy wetlands

    NASA Astrophysics Data System (ADS)

    Martinson, G. O.; Conrad, R.

    2012-12-01

    Ground wetlands are the main natural source of methane but they fail to explain the observed amounts of methane over tropical forests. Bromeliad tanks are discrete habitats for aquatic organisms and up to several thousand of bromeliad individuals per hectare of tropical forest create a unique canopy wetland ecosystem in neotropical forests. Recently, we have discovered that canopy wetlands inhabit methanogenic archaea, emit substantial amounts of methane and may help to explain the high amounts of methane over neotropical forests. However, the pathway of methane formation and potential methane production in canopy wetlands of different tropical forest ecosystems have not yet been studied. In this study, we investigated the stable carbon isotope fractionation, methanogenic pathway and potential methane production of bromeliad tanks along an elevation gradient in neotropical forests for the first time. We sampled the bromeliad tank-substrate of 3 tank bromeliads per functional type and elevation (1000 m, 2000 m and 3000 m above the sea level). We distinguished three functional types of tank bromeliads, based on plant architecture and ecological niche preference. Functional type I-tank bromeliads are concentrated in the understory and on the ground. Functional type II and type III are concentrated in the mid and overstory. We conducted tank-substrate incubation experiments and measured CH4, CO2, 13CH4 and 13CO2 at regular time intervals during the incubation period. The methane production potential of bromeliad tanks correlated positively with tank-substrate carbon concentration and decreased with increasing canopy height and increasing elevation. The dominant pathway of methane formation in bromeliad tanks was hydrogenotrophic methanogenesis (>50%) and this dominance increased with increasing canopy height and increasing elevation. Our results provide novel insights into the pathway of methane formation in neotropical canopy wetlands and suggest that canopy height is

  10. Displaceable Gear Torque Controlled Driver

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1997-01-01

    Methods and apparatus are provided for a torque driver including a displaceable gear to limit torque transfer to a fastener at a precisely controlled torque limit. A biasing assembly biases a first gear into engagement with a second gear for torque transfer between the first and second gear. The biasing assembly includes a pressurized cylinder controlled at a constant pressure that corresponds to a torque limit. A calibrated gage and valve is used to set the desired torque limit. One or more coiled output linkages connect the first gear with the fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. The torque limit is adjustable and may be different for fasteners within the same fastener configuration.

  11. Variable delivery, fixed displacement pump

    DOEpatents

    Sommars, Mark F.

    2001-01-01

    A variable delivery, fixed displacement pump comprises a plurality of pistons reciprocated within corresponding cylinders in a cylinder block. The pistons are reciprocated by rotation of a fixed angle swash plate connected to the pistons. The pistons and cylinders cooperate to define a plurality of fluid compression chambers each have a delivery outlet. A vent port is provided from each fluid compression chamber to vent fluid therefrom during at least a portion of the reciprocal stroke of the piston. Each piston and cylinder combination cooperates to close the associated vent port during another portion of the reciprocal stroke so that fluid is then pumped through the associated delivery outlet. The delivery rate of the pump is varied by adjusting the axial position of the swash plate relative to the cylinder block, which varies the duration of the piston stroke during which the vent port is closed.

  12. Polybenzimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

    1995-01-01

    Novel molecular weight controlled and endcapped polybenzimidazoles (PBI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The PBI are endcapped with mono(hydroxyphenyl) benzimidazoles. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. Mono(hydroxyphenyl) benzimidazoles are synthesizedby reacting phenyl-4-hydroxybenzoate with aromatic (o-diamine)s in diphenylsulfone. Molecular weight controlled and endcapped PBI of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

  13. Displaced electrode process for welding

    DOEpatents

    Heichel, L.J.

    1975-08-26

    A method is described for the butt-welding of a relatively heavy mass to a relatively small mass such as a thin-wall tube. In butt-welding heat is normally applied at the joint between the two pieces which are butt-welded together. The application of heat at the joint results in overheating the tube which causes thinning of the tube walls and porosity in the tube material. This is eliminated by displacing the welding electrode away from the seam toward the heavier mass so that heat is applied to the heavy mass and not at the butt seam. Examples of the parameters used in welding fuel rods are given. The cladding and end plugs were made of Zircalloy. The electrode used was of 2 percent thoriated tungsten. (auth)

  14. Polyimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor)

    1991-01-01

    Polyimidazoles (Pl) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethylacetamide, sulfolane, N-methylpyrroldinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperature under nitrogen. The di(hydroxyphenyl)imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl)imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxyphenyl)imidazole monomer. This synthetic route has provided high molecular weight Pl of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

  15. Polybenzimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergerrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

    1997-01-01

    Novel molecular weight controlled and endcapped polybenzimidazoles (PBI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenylbenzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The PBI are endcapped with mono(hydroxyphenyl)benzimidazoles. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. Mono(hydroxyphenyl)benzimidazoles are synthesized by reacting phenyl-4-hydroxybenzoate with aromatic (o-diamine)s in diphenylsulfone. Molecular weight controlled and endcapped PBI of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

  16. Polyimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor)

    1992-01-01

    Polyimidazoles (PI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl) imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethyl acetamide, sulfolane, N-methylpyrrolidinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl) imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl) imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxphenyl) imidazole monomer. This synthetic route has provided high molecular weight PI of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

  17. In silico design of porous polymer networks: high-throughput screening for methane storage materials.

    PubMed

    Martin, Richard L; Simon, Cory M; Smit, Berend; Haranczyk, Maciej

    2014-04-01

    Porous polymer networks (PPNs) are a class of advanced porous materials that combine the advantages of cheap and stable polymers with the high surface areas and tunable chemistry of metal-organic frameworks. They are of particular interest for gas separation or storage applications, for instance, as methane adsorbents for a vehicular natural gas tank or other portable applications. PPNs are self-assembled from distinct building units; here, we utilize commercially available chemical fragments and two experimentally known synthetic routes to design in silico a large database of synthetically realistic PPN materials. All structures from our database of 18,000 materials have been relaxed with semiempirical electronic structure methods and characterized with Grand-canonical Monte Carlo simulations for methane uptake and deliverable (working) capacity. A number of novel structure-property relationships that govern methane storage performance were identified. The relationships are translated into experimental guidelines to realize the ideal PPN structure. We found that cooperative methane-methane attractions were present in all of the best-performing materials, highlighting the importance of guest interaction in the design of optimal materials for methane storage.

  18. Competitive displacement among insects and arachnids.

    PubMed

    Reitz, Stuart R; Trumble, John T

    2002-01-01

    Competitive displacement is the most severe outcome of interspecific competition. For the purposes of this review, we define this type of displacement as the removal of a formerly established species from a habitat as a result of direct or indirect competitive interactions with another species. We reviewed the literature for recent putative cases of competitive displacement among insects and arachnids and assessed the evidence for the role of interspecific competition in these displacements. We found evidence for mechanisms of both exploitation and interference competition operating in these cases of competitive displacement. Many of the cases that we identified involve the operation of more than one competitive mechanism, and many cases were mediated by other noncompetitive factors. Most, but not all, of these displacements occurred between closely related species. In the majority of cases, exotic species displaced native species or previously established exotic species, often in anthropogenically-altered habitats. The cases that we identified have occurred across a broad range of taxa and environments. Therefore we suggest that competitive displacement has the potential to be a widespread phenomenon, and the frequency of these displacement events may increase, given the ever-increasing degree of anthropogenic changes to the environment. A greater awareness of competitive displacement events should lead to more studies documenting the relative importance of key factors and developing hypotheses that explain observed patterns.

  19. Exploring the Limits of Methane Storage and Delivery in Nanoporous Materials

    SciTech Connect

    Gomez-Gualdron, DA; Wilmer, CE; Farha, OK; Hupp, JT; Snurr, RQ

    2014-04-03

    The physical limits for methane storage and delivery in nanoporous materials were investigated, with a focus on whether it is possible to reach a methane deliverable capacity of 315 cm(3)(STP)/cm(3) in line with the adsorption target established by the ARPA-E agency. Our efforts focused on how both geometric and chemical properties, such as void fraction (V-f), volumetric surface area (S-v), and heat of adsorption (Q(st)), impact methane deliverable capacity, i.e., the amount of methane adsorbed at some storage pressure minus the amount adsorbed at the delivery pressure. With the aid of grand canonical Monte Carlo (GCMC) simulations, we studied methane adsorption and delivery properties in a population of 122 835 hypothetical pcu metal organic frameworks (MOFs) and 39 idealized carbon-based porous materials. From the simulation results, we developed an analytical equation that helped us delimit the necessary material properties to reach specific methane deliverable capacity targets. The maximum deliverable capacity between 65 and 5.8 bar among the hypothetical MOFs was 206 cm(3)(STP)/cm(3) at 298 K. We found that artificially increasing the methane MOF interaction strength by increasing the Lennard-Jones e parameters of the MOF atoms by 2- and 4-fold only improved the maximum deliverable capacity up to 223 and 228 cm(3)(STP)/cm(3), respectively. However, the effect on the amount stored at 65 bar was more significant, which suggested another strategy; raising the temperature of the system by 100 K can recover 70% of the methane stranded at the delivery pressure. By increasing the delivery temperature to 398 K, the ARPA-E target was reached by a few hypothetical MOFs with quadrupled e values. This work shows the difficulty in reaching the ARPA-E target but also suggests that a strategy that combines a material with a large volumetric density of sites that interact strongly with methane and raising the delivery temperature can greatly improve the performance of

  20. Natural Transformation of Azotobacter vinelandii by Adsorbed Chromosomal DNA: Role of Adsorbed DNA Conformation

    NASA Astrophysics Data System (ADS)

    Lv, N.; Zilles, J.; Nguyen, H.

    2008-12-01

    Recent increases in antibiotic resistance among pathogenic microorganisms and the accompanying public health concerns result both from the widespread use of antibiotics and from the transfer of antibiotic resistance genes among microorganisms. To understand the transfer of antibiotic resistance genes and identify efficient measures to minimize these transfers, an interdisciplinary approach was used to identify physical and chemical factors that control the fate and biological availability of extracellular DNA. Quartz crystal microbalance with dissipation (QCM-D) was used to study extracellular DNA adsorption and the conformation of the adsorbed DNA on silica and natural organic matter (NOM) surfaces. Solution chemistry was varied systematically to investigate the role of adsorbed DNA conformation on transformation. Gene transfer was assessed under the same conditions using natural transformation of chromosomal DNA into the soil bacteria Azotobacter vinelandii. DNA adsorbed to both silica and NOM surfaces has a more compact and rigid conformation in the presence of Ca2+ compared to Na+. Extracellular DNA adsorbed on silica and NOM surfaces transformed A. vinelandii. The transformation efficiency of adsorbed DNA was up to 4 orders of magnitude lower than that of dissolved DNA. Preliminary results suggest that the presence of Ca2+ in groundwater (e.g. hardness) reduces the availability of adsorbed DNA for transformation.

  1. Dielectric Barrier Discharge Methane Conversion

    NASA Astrophysics Data System (ADS)

    Liu, Chong; Fridman, Alexander; Rabinovich, Alexander; Dobrynin, Danil

    2015-09-01

    With the large amount of nature gas discovery every year, there is an increasing interest on modification of methane. The fact that methane is gaseous makes it less economic and efficient than liquid fuel. Here we propose a new way of converting methane from gas phase to liquid phase. Dielectric barrier discharge is used to treat methane and nitrogen mixture bubbles inside of liquid fuel. Nitrogen is here to help activate methane into an excited state, then it is possible for the excited molecules to react with other liquid hydrocarbon. Gaseous methane is converted in to liquid phase when excited methane replace a hydrogen and add onto the carbon chain. In this study some preliminary experiments is done to verify this hypothesis. There is equivalent weight increases with methane and nitrogen mixture discharging in diesel when compare to only nitrogen discharging in diesel. The same experiment have also been done with gas mixture discharged in 1-methylnaphthalene. And FTIR analysis of the after treatment hydrocarbon liquid all indicates that there is an increasing in C-H bond concentration and a decreasing in phenyl ring structure.

  2. A Methane Balloon Inflation Chamber

    ERIC Educational Resources Information Center

    Czerwinski, Curtis J.; Cordes, Tanya J.; Franek, Joe

    2005-01-01

    The various equipments, procedure and hazards in constructing the device for inflating a methane balloon using a standard methane outlet in a laboratory are described. This device is fast, safe, inexpensive, and easy to use as compared to a hydrogen gas cylinder for inflating balloons.

  3. Pore size distribution analysis of activated carbons prepared from coconut shell using methane adsorption data

    NASA Astrophysics Data System (ADS)

    Ahmadpour, A.; Okhovat, A.; Darabi Mahboub, M. J.

    2013-06-01

    The application of Stoeckli theory to determine pore size distribution (PSD) of activated carbons using high pressure methane adsorption data is explored. Coconut shell was used as a raw material for the preparation of 16 different activated carbon samples. Four samples with higher methane adsorption were selected and nitrogen adsorption on these adsorbents was also investigated. Some differences are found between the PSD obtained from the analysis of nitrogen adsorption isotherms and their PSD resulting from the same analysis using methane adsorption data. It is suggested that these differences may arise from the specific interactions between nitrogen molecules and activated carbon surfaces; therefore caution is required in the interpretation of PSD obtained from the nitrogen isotherm data.

  4. Mechanisms and controlling characteristics of the oxidation of methane. Progress report

    SciTech Connect

    Klier, K.; Simmons, G.W.

    1985-02-13

    The research aims at the scientific foundations for processes dealing with selective oxidation of methane to methanol and formaldehyde. Progress has been achieved in two major areas: (a) Catalytic oxidation of methane to formaldehyde by molecular oxygen over molybdena-based catalysts at subatmospheric pressures; the catalysts have been characterized by laser Raman microprobe, electron microscopy, EPR, and ESCA/Auger spectroscopy; (b) Surface science of adsorbates in the palladium-oxygen-dichloromethane-methane system. A combined LEED/Auger/Mass Spectrometer apparatus dedicated to this project has been constructed and is in operation. The structures, energetics, and desorption patterns of oxygen and dichloromethane overlayers have been determined on the Pd(100) crystal surface. An interesting exclusion of dichloromethane chemisorption by preadsorbed oxygen and the occurrence of oxygen chemisorption into the dichloromethane overlayer indicate a reaction pattern that will be very sensitive to the gas phase oxygen-to-dichloromethane concentration ratio.

  5. Constraining Methane Flux Estimates Using Atmospheric Observations of Methane and 1^3C in Methane

    NASA Astrophysics Data System (ADS)

    Mikaloff Fletcher, S. E.; Tans, P. P.; Miller, J. B.; Bruhwiler, L. M.

    2002-12-01

    Understanding the budget of methane is crucial to predicting climate change and managing earth's carbon reservoirs. Methane is responsible for approximately 15% of the anthropogenic greenhouse forcing and has a large impact on the oxidative capacity of Earth's atmosphere due to its reaction with hydroxyl radical. At present, many of the sources and sinks of methane are poorly understood due in part to the large spatial and temporal variability of the methane flux. Model simulations of methane mixing ratios using most process-based source estimates typically over-predict the latitudinal gradient of atmospheric methane relative to the observations; however, the specific source processes responsible for this discrepancy have not been identified definitively. The aim of this work is to use the isotopic signatures of the sources to attribute these discrepancies to a source process or group of source processes and create global and regional budget estimates that are in agreement with both the atmospheric observations of methane and 1^3C in methane. To this end, observations of isotopic ratios of 1^3C in methane and isotopic signatures of methane source processes are used in conjunction with an inverse model of the methane budget. Inverse modeling is a top-down approach which uses observations of trace gases in the atmosphere, an estimate of the spatial pattern of trace gas fluxes, and a model of atmospheric transport to estimate the sources and sinks. The atmospheric transport was represented by the TM3 three-dimensional transport model. The GLOBALVIEW 2001 methane observations were used along with flask measurements of 1^3C in methane at six of the CMDL-NOAA stations by INSTAAR. Initial results imply interesting differences from previous methane budget estimates. For example, the 1^3C isotope observations in methane call for an increase in southern hemisphere sources with a bacterial isotopic signature such as wetlands, rice paddies, termites, and ruminant animals. The

  6. Aluminosilicate-based adsorbent in equimolar and non-equimolar binary-component heavy metal removal systems.

    PubMed

    Xu, Meng; Hadi, Pejman; Ning, Chao; Barford, John; An, Kyoung Jin; McKay, Gordon

    2015-01-01

    Cadmium (Cd) and lead (Pb) are toxic heavy metals commonly used in various industries. The simultaneous presence of these metals in wastewater amplifies the toxicity of wastewater and the complexity of the treatment process. This study has investigated the selective behavior of an aluminosilicate-based mesoporous adsorbent. It has been demonstrated that when equimolar quantities of the metals are present in wastewater, the adsorbent uptakes the Pb²⁺ ions selectively. This has been attributed to the higher electronegativity value of Pb²⁺ compared to Cd²⁺ which can be more readily adsorbed on the adsorbent surface, displacing the Cd²⁺ ions. The selectivity can be advantageous when the objective is the separation and reuse of the metals besides wastewater treatment. In non-equimolar solutions, a complete selectivity can be observed up to a threshold Pb²⁺ molar ratio of 30%. Below this threshold value, the Cd²⁺ and Pb²⁺ ions are uptaken simultaneously due to the abundance of Cd²⁺ ions and the availability of adsorption sites at very low Pb²⁺ molar ratios. Moreover, the total adsorption capacities of the adsorbent for the multi-component system have been shown to be in the same range as the single-component system for each metal ion which can be of high value for industrial applications. PMID:26676004

  7. Aluminosilicate-based adsorbent in equimolar and non-equimolar binary-component heavy metal removal systems.

    PubMed

    Xu, Meng; Hadi, Pejman; Ning, Chao; Barford, John; An, Kyoung Jin; McKay, Gordon

    2015-01-01

    Cadmium (Cd) and lead (Pb) are toxic heavy metals commonly used in various industries. The simultaneous presence of these metals in wastewater amplifies the toxicity of wastewater and the complexity of the treatment process. This study has investigated the selective behavior of an aluminosilicate-based mesoporous adsorbent. It has been demonstrated that when equimolar quantities of the metals are present in wastewater, the adsorbent uptakes the Pb²⁺ ions selectively. This has been attributed to the higher electronegativity value of Pb²⁺ compared to Cd²⁺ which can be more readily adsorbed on the adsorbent surface, displacing the Cd²⁺ ions. The selectivity can be advantageous when the objective is the separation and reuse of the metals besides wastewater treatment. In non-equimolar solutions, a complete selectivity can be observed up to a threshold Pb²⁺ molar ratio of 30%. Below this threshold value, the Cd²⁺ and Pb²⁺ ions are uptaken simultaneously due to the abundance of Cd²⁺ ions and the availability of adsorption sites at very low Pb²⁺ molar ratios. Moreover, the total adsorption capacities of the adsorbent for the multi-component system have been shown to be in the same range as the single-component system for each metal ion which can be of high value for industrial applications.

  8. EMERGING TECHNOLOGY SUMMARY: DEMONSTRATION OF AMBERSORB 563 ADSORBENT TECHNOLOGY

    EPA Science Inventory

    A field pilot study was conducted to demonstrate the technical feasibility and cost-effectiveness of Ambersorb® 5631 carbonaceous adsorbent for remediating groundwater contaminated with volatile organic compounds (VOCs). The Ambersorb adsorbent technology demonstration consist...

  9. Coal mine methane global review

    SciTech Connect

    2008-07-01

    This is the second edition of the Coal Mine Methane Global Overview, updated in the summer of 2008. This document contains individual, comprehensive profiles that characterize the coal and coal mine methane sectors of 33 countries - 22 methane to market partners and an additional 11 coal-producing nations. The executive summary provides summary tables that include statistics on coal reserves, coal production, methane emissions, and CMM projects activity. An International Coal Mine Methane Projects Database accompanies this overview. It contains more detailed and comprehensive information on over two hundred CMM recovery and utilization projects around the world. Project information in the database is updated regularly. This document will be updated annually. Suggestions for updates and revisions can be submitted to the Administrative Support Group and will be incorporate into the document as appropriate.

  10. Oxygen-Methane Thruster

    NASA Technical Reports Server (NTRS)

    Pickens, Tim

    2012-01-01

    An oxygen-methane thruster was conceived with integrated igniter/injector capable of nominal operation on either gaseous or liquid propellants. The thruster was designed to develop 100 lbf (approximately 445 N) thrust at vacuum conditions and use oxygen and methane as propellants. This continued development included refining the design of the thruster to minimize part count and manufacturing difficulties/cost, refining the modeling tools and capabilities that support system design and analysis, demonstrating the performance of the igniter and full thruster assembly with both gaseous and liquid propellants, and acquiring data from this testing in order to verify the design and operational parameters of the thruster. Thruster testing was conducted with gaseous propellants used for the igniter and thruster. The thruster was demonstrated to work with all types of propellant conditions, and provided the desired performance. Both the thruster and igniter were tested, as well as gaseous propellants, and found to provide the desired performance using the various propellant conditions. The engine also served as an injector testbed for MSFC-designed refractory combustion chambers made of rhenium.

  11. Making methane visible

    NASA Astrophysics Data System (ADS)

    Gålfalk, Magnus; Olofsson, Göran; Crill, Patrick; Bastviken, David

    2016-04-01

    Methane (CH4) is one of the most important greenhouse gases, and an important energy carrier in biogas and natural gas. Its large scale emission patterns have been unpredictable and the source and sink distributions are poorly constrained. Remote assessment of CH4 with high sensitivity at m2 spatial resolution would allow detailed mapping of near ground distribution and anthropogenic sources and sinks in landscapes but has hitherto not been possible. Here we show that CH4 gradients can be imaged on methane imaging will include a lake, barn, sewage sludge deposit, waste incineration plant, and controlled gas releases. We will also present successful simultaneous imaging of another important greenhouse gas, nitrous oxide, with the same instrument.

  12. Search for interstellar methane

    NASA Technical Reports Server (NTRS)

    Knacke, R. F.; Kim, Y. H.; Noll, K. S.; Geballe, T. R.

    1990-01-01

    Researchers searched for interstellar methane in the spectra of infrared sources embedded in molecular clouds. New observations of several lines of the P and R branches of the nu 3 band of CH4 near 3.3 microns give column densities in the range N less than 1(-2) times 10 to the minus 16th power cm(-2). Resulting abundance ratios are (CH4)/(CO) less than 3.3 times 10 to the minus 2nd power toward GL961 in NGC 2244 and less than 2.4 times 10 to the minus 3rd power toward GL989 in the NGC 2264 molecular cloud. The limits, and those determined in earlier observations of BN in Orion and GL490, suggest that there is little methane in molecular clouds. The result agrees with predictions of chemical models. Exceptions could occur in clouds where oxygen may be depleted, for example by H2O freezing on grains. The present observations probably did not sample such regions.

  13. Study of deep profile control and oil displacement technologies with nanoscale polymer microspheres.

    PubMed

    Hua, Zhao; Lin, Meiqin; Dong, Zhaoxia; Li, Mingyuan; Zhang, Guiqing; Yang, Jie

    2014-06-15

    Scanning electron microscopy (SEM), dynamic lighting scattering (DLS) and HAAKE rheometer experiments were adopted to investigate the shape, size and rheological properties of nanoscale polymer microspheres. Moreover, nuclear-pore film filtration, sand packed tube displacement, core displacement, micro-visual model and capillary flow experiments were used to study the mechanisms of deep profile control and oil displacement of nanoscale polymer microspheres. The results demonstrated that the original shape of the nanoscale polymer microspheres were typically spherical, ranging in size from 30 to 60 nm. When the microspheres were dispersed in water, their size increased by 3-6 times due to swelling and a poly-dispersed system appeared; however, the spherical conformation remained. Within a certain range of shear rates, a 100-900 mg/L microsphere dispersed system exhibited shear thickening behaviour, making it favourable for increasing the flow resistance of a displacement fluid. These polymer microspheres dispersed systems exhibited effective plugging on a nuclear pore film with 0.4-μm pores with deep plugging in the core; these systems also tended to plug the high permeability layer and drive crude oil from the low permeability layer in parallel sand packed tubes. Cross-linked polymer microspheres could reduce water permeability because the microspheres adsorbed, accumulated and bridged in the pore-throat, and the adsorbed layers would be collapsed under the pressure, entering deep into the reservoir due to the good deformation properties of the microspheres. Meanwhile these microspheres would drive crude oil on and in the pores/throats while they are transported in porous media, achieving deep profile control and oil displacement with the ultimate purpose of improving oil recovery. PMID:24767500

  14. Study of deep profile control and oil displacement technologies with nanoscale polymer microspheres.

    PubMed

    Hua, Zhao; Lin, Meiqin; Dong, Zhaoxia; Li, Mingyuan; Zhang, Guiqing; Yang, Jie

    2014-06-15

    Scanning electron microscopy (SEM), dynamic lighting scattering (DLS) and HAAKE rheometer experiments were adopted to investigate the shape, size and rheological properties of nanoscale polymer microspheres. Moreover, nuclear-pore film filtration, sand packed tube displacement, core displacement, micro-visual model and capillary flow experiments were used to study the mechanisms of deep profile control and oil displacement of nanoscale polymer microspheres. The results demonstrated that the original shape of the nanoscale polymer microspheres were typically spherical, ranging in size from 30 to 60 nm. When the microspheres were dispersed in water, their size increased by 3-6 times due to swelling and a poly-dispersed system appeared; however, the spherical conformation remained. Within a certain range of shear rates, a 100-900 mg/L microsphere dispersed system exhibited shear thickening behaviour, making it favourable for increasing the flow resistance of a displacement fluid. These polymer microspheres dispersed systems exhibited effective plugging on a nuclear pore film with 0.4-μm pores with deep plugging in the core; these systems also tended to plug the high permeability layer and drive crude oil from the low permeability layer in parallel sand packed tubes. Cross-linked polymer microspheres could reduce water permeability because the microspheres adsorbed, accumulated and bridged in the pore-throat, and the adsorbed layers would be collapsed under the pressure, entering deep into the reservoir due to the good deformation properties of the microspheres. Meanwhile these microspheres would drive crude oil on and in the pores/throats while they are transported in porous media, achieving deep profile control and oil displacement with the ultimate purpose of improving oil recovery.

  15. Displacement speeds in turbulent premixed flame simulations

    SciTech Connect

    Day, Marcus S.; Shepherd, Ian G.; Bell, J.; Grcar, Joseph F.; Lijewski, Michael J.

    2007-07-01

    The theory of turbulent premixed flames is based on acharacterization of the flame as a discontinuous surface propagatingthrough the fluid. The displacement speed, defined as the local speed ofthe flame front normal to itself, relative to the unburned fluid,provides one characterization of the burning velocity. In this paper, weintroduce a geometric approach to computing displacement speed anddiscuss the efficacy of the displacement speed for characterizing aturbulent flame.

  16. Hydroxylation of methane through component interactions in soluble methane monooxygenases.

    PubMed

    Lee, Seung Jae

    2016-04-01

    Methane hydroxylation through methane monooxygenases (MMOs) is a key aspect due to their control of the carbon cycle in the ecology system and recent applications of methane gas in the field of bioenergy and bioremediation. Methanotropic bacteria perform a specific microbial conversion from methane, one of the most stable carbon compounds, to methanol through elaborate mechanisms. MMOs express particulate methane monooxygenase (pMMO) in most strains and soluble methane monooxygenase (sMMO) under copper-limited conditions. The mechanisms of MMO have been widely studied from sMMO belonging to the bacterial multicomponent monooxygenase (BMM) superfamily. This enzyme has diiron active sites where different types of hydrocarbons are oxidized through orchestrated hydroxylase, regulatory and reductase components for precise control of hydrocarbons, oxygen, protons, and electrons. Recent advances in biophysical studies, including structural and enzymatic achievements for sMMO, have explained component interactions, substrate pathways, and intermediates of sMMO. In this account, oxidation of methane in sMMO is discussed with recent progress that is critical for understanding the microbial applications of C-H activation in one-carbon substrates.

  17. Displacement based multilevel structural optimization

    NASA Technical Reports Server (NTRS)

    Striz, Alfred G.

    1995-01-01

    Multidisciplinary design optimization (MDO) is expected to play a major role in the competitive transportation industries of tomorrow, i.e., in the design of aircraft and spacecraft, of high speed trains, boats, and automobiles. All of these vehicles require maximum performance at minimum weight to keep fuel consumption low and conserve resources. Here, MDO can deliver mathematically based design tools to create systems with optimum performance subject to the constraints of disciplines such as structures, aerodynamics, controls, etc. Although some applications of MDO are beginning to surface, the key to a widespread use of this technology lies in the improvement of its efficiency. This aspect is investigated here for the MDO subset of structural optimization, i.e., for the weight minimization of a given structure under size, strength, and displacement constraints. Specifically, finite element based multilevel optimization of structures (here, statically indeterminate trusses and beams for proof of concept) is performed. In the system level optimization, the design variables are the coefficients of assumed displacement functions, and the load unbalance resulting from the solution of the stiffness equations is minimized. Constraints are placed on the deflection amplitudes and the weight of the structure. In the subsystems level optimizations, the weight of each element is minimized under the action of stress constraints, with the cross sectional dimensions as design variables. This approach is expected to prove very efficient, especially for complex structures, since the design task is broken down into a large number of small and efficiently handled subtasks, each with only a small number of variables. This partitioning will also allow for the use of parallel computing, first, by sending the system and subsystems level computations to two different processors, ultimately, by performing all subsystems level optimizations in a massively parallel manner on separate

  18. Computer simulations of adsorbed liquid crystal films

    NASA Astrophysics Data System (ADS)

    Wall, Greg D.; Cleaver, Douglas J.

    2003-01-01

    The structures adopted by adsorbed thin films of Gay-Berne particles in the presence of a coexisting vapour phase are investigated by molecular dynamics simulation. The films are adsorbed at a flat substrate which favours planar anchoring, whereas the nematic-vapour interface favours normal alignment. On cooling, a system with a high molecule-substrate interaction strength exhibits substrate-induced planar orientational ordering and considerable stratification is observed in the density profiles. In contrast, a system with weak molecule-substrate coupling adopts a director orientation orthogonal to the substrate plane, owing to the increased influence of the nematic-vapour interface. There are significant differences between the structures adopted at the two interfaces, in contrast with the predictions of density functional treatments of such systems.

  19. Magnesium silicates adsorbents of organic compounds

    NASA Astrophysics Data System (ADS)

    Ciesielczyk, Filip; Krysztafkiewicz, Andrzej; Jesionowski, Teofil

    2007-08-01

    Studies were presented on production of highly dispersed magnesium silicate at a pilote scale. The process of silicate adsorbent production involved precipitation reaction using water glass (sodium metasilicate) solution and appropriate magnesium salt, preceded by an appropriate optimization stage. Samples of best physicochemical parameters were in addition modified (in order to introduce to silica surface of several functional groups) using the dry technique and various amounts of 3-isocyanatepropyltrimethoxysilane, 3-thiocyanatepropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane. The so prepared samples were subjected to a comprehensive physicochemical analysis. At the terminal stage of studies attempts were made to adsorb phenol from its aqueous solutions on the surface of unmodified and modified magnesium silicates. Particle size distributions were determined using the ZetaSizer Nano ZS apparatus. In order to define adsorptive properties of studied magnesium silicates isotherms of nitrogen adsorption/desorption on their surfaces were established. Efficiency of phenol adsorption was tested employing analysis of post-adsorption solution.

  20. Analysis of Adsorbed Natural Gas Tank Technology

    NASA Astrophysics Data System (ADS)

    Knight, Ernest; Schultz, Conrad; Rash, Tyler; Dohnke, Elmar; Stalla, David; Gillespie, Andrew; Sweany, Mark; Seydel, Florian; Pfeifer, Peter

    With gasoline being an ever decreasing finite resource and with the desire to reduce humanity's carbon footprint, there has been an increasing focus on innovation of alternative fuel sources. Natural gas burns cleaner, is more abundant, and conforms to modern engines. However, storing compressed natural gas (CNG) requires large, heavy gas cylinders, which limits space and fuel efficiency. Adsorbed natural gas (ANG) technology allows for much greater fuel storage capacity and the ability to store the gas at a much lower pressure. Thus, ANG tanks are much more flexible in terms of their size, shape, and weight. Our ANG tank employs monolithic nanoporous activated carbon as its adsorbent material. Several different configurations of this Flat Panel Tank Assembly (FPTA) along with a Fuel Extraction System (FES) were examined to compare with the mass flow rate demands of an engine.

  1. Gas storage using fullerene based adsorbents

    NASA Technical Reports Server (NTRS)

    Loutfy, Raouf O. (Inventor); Lu, Xiao-Chun (Inventor); Li, Weijiong (Inventor); Mikhael, Michael G. (Inventor)

    2000-01-01

    This invention is directed to the synthesis of high bulk density high gas absorption capacity adsorbents for gas storage applications. Specifically, this invention is concerned with novel gas absorbents with high gravimetric and volumetric gas adsorption capacities which are made from fullerene-based materials. By pressing fullerene powder into pellet form using a conventional press, then polymerizing it by subjecting the fullerene to high temperature and high inert gas pressure, the resulting fullerene-based materials have high bulk densities and high gas adsorption capacities. By pre-chemical modification or post-polymerization activation processes, the gas adsorption capacities of the fullerene-based adsorbents can be further enhanced. These materials are suitable for low pressure gas storage applications, such as oxygen storage for home oxygen therapy uses or on-board vehicle natural gas storage. They are also suitable for storing gases and vapors such as hydrogen, nitrogen, carbon dioxide, and water vapor.

  2. Displacement of Propagating Squeezed Microwave States

    NASA Astrophysics Data System (ADS)

    Fedorov, Kirill G.; Zhong, L.; Pogorzalek, S.; Eder, P.; Fischer, M.; Goetz, J.; Xie, E.; Wulschner, F.; Inomata, K.; Yamamoto, T.; Nakamura, Y.; Di Candia, R.; Las Heras, U.; Sanz, M.; Solano, E.; Menzel, E. P.; Deppe, F.; Marx, A.; Gross, R.

    2016-07-01

    Displacement of propagating quantum states of light is a fundamental operation for quantum communication. It enables fundamental studies on macroscopic quantum coherence and plays an important role in quantum teleportation protocols with continuous variables. In our experiments, we have successfully implemented this operation for propagating squeezed microwave states. We demonstrate that, even for strong displacement amplitudes, there is no degradation of the squeezing level in the reconstructed quantum states. Furthermore, we confirm that path entanglement generated by using displaced squeezed states remains constant over a wide range of the displacement power.

  3. Displacement of Propagating Squeezed Microwave States.

    PubMed

    Fedorov, Kirill G; Zhong, L; Pogorzalek, S; Eder, P; Fischer, M; Goetz, J; Xie, E; Wulschner, F; Inomata, K; Yamamoto, T; Nakamura, Y; Di Candia, R; Las Heras, U; Sanz, M; Solano, E; Menzel, E P; Deppe, F; Marx, A; Gross, R

    2016-07-01

    Displacement of propagating quantum states of light is a fundamental operation for quantum communication. It enables fundamental studies on macroscopic quantum coherence and plays an important role in quantum teleportation protocols with continuous variables. In our experiments, we have successfully implemented this operation for propagating squeezed microwave states. We demonstrate that, even for strong displacement amplitudes, there is no degradation of the squeezing level in the reconstructed quantum states. Furthermore, we confirm that path entanglement generated by using displaced squeezed states remains constant over a wide range of the displacement power. PMID:27447495

  4. Displacement of Propagating Squeezed Microwave States.

    PubMed

    Fedorov, Kirill G; Zhong, L; Pogorzalek, S; Eder, P; Fischer, M; Goetz, J; Xie, E; Wulschner, F; Inomata, K; Yamamoto, T; Nakamura, Y; Di Candia, R; Las Heras, U; Sanz, M; Solano, E; Menzel, E P; Deppe, F; Marx, A; Gross, R

    2016-07-01

    Displacement of propagating quantum states of light is a fundamental operation for quantum communication. It enables fundamental studies on macroscopic quantum coherence and plays an important role in quantum teleportation protocols with continuous variables. In our experiments, we have successfully implemented this operation for propagating squeezed microwave states. We demonstrate that, even for strong displacement amplitudes, there is no degradation of the squeezing level in the reconstructed quantum states. Furthermore, we confirm that path entanglement generated by using displaced squeezed states remains constant over a wide range of the displacement power.

  5. Effective Thermal Conductivity of Adsorbent Packed Beds

    NASA Astrophysics Data System (ADS)

    Mori, Hideo; Hamamoto, Yoshinori; Yoshida, Suguru

    The effective thermal conductivity of adsorbent packed beds of granular zeolite 13X and granular silica gel A in the presence of stagnant steam or air was measured under different conditions of the adsorbent bed temperature, particle size and filler-gas pressure. The measured effective thermal conductivity showed to become smaller with decreasing particle size or decreasing pressure, but it was nearly independent of the bed temperature. When steam was the filler-gas, the rise in the thermal conductivity of the adsorbent particles due to steam adsorption led to the increase in the effective thermal conductivity of the bed, and this effect was not negligible at high steam pressure for the bed of large particle size. It was found that both the predictions of the effective thermal conductivity by the Hayashi et al.'s model and the Bauer-Schlünder model generally agreed well with the measurements, by considering the particle thermal conductivity rise due to steam adsorption. The thermal conductivity of a consolidated bed of granular zeolite 13X was also measured, and it was found to be much larger than that of the packed bed especially at lower pressure. The above prediction models underestimated the effective thermal conductivity of the consolidated bed.

  6. Orbital tomography for highly symmetric adsorbate systems

    NASA Astrophysics Data System (ADS)

    Stadtmüller, B.; Willenbockel, M.; Reinisch, E. M.; Ules, T.; Bocquet, F. C.; Soubatch, S.; Puschnig, P.; Koller, G.; Ramsey, M. G.; Tautz, F. S.; Kumpf, C.

    2012-10-01

    Orbital tomography is a new and very powerful tool to analyze the angular distribution of a photoemission spectroscopy experiment. It was successfully used for organic adsorbate systems to identify (and consequently deconvolute) the contributions of specific molecular orbitals to the photoemission data. The technique was so far limited to surfaces with low symmetry like fcc(110) oriented surfaces, owing to the small number of rotational domains that occur on such surfaces. In this letter we overcome this limitation and present an orbital tomography study of a 3,4,9,10-perylene-tetra-carboxylic-dianhydride (PTCDA) monolayer film adsorbed on Ag(111). Although this system exhibits twelve differently oriented molecules, the angular resolved photoemission data still allow a meaningful analysis of the different local density of states and reveal different electronic structures for symmetrically inequivalent molecules. We also discuss the precision of the orbital tomography technique in terms of counting statistics and linear regression fitting algorithm. Our results demonstrate that orbital tomography is not limited to low-symmetry surfaces, a finding which makes a broad field of complex adsorbate systems accessible to this powerful technique.

  7. Polybenzoxazole via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M. (Inventor); Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor)

    1993-01-01

    Polybenzoxazoles (PBO) are heterocyclic macromolecules which were first synthesized in a two-step process by the initial formation of aromatic diacid chlorides with bis(o-aminophenol)s through solution condensation of aromatic diacid chlorides with bis(o-aminophenol)s followed by thermal cyclodehydration. Since then several methods were utilized in their synthesis. The most common synthetic method for PBO involves a polycondensation of bis(o-aminophenol)s with aromatic diacid diphenyl esters. Another preparative route involves the solution polycondensation of the hydrochloride salts of bis(o-amino phenol)s with aromatic diacids in polyphosphoric acid. Another synthetic method involves the initial formation of poly(o-hydroxy amide)s from silylated bis(o-aminophenol)s with aromatic diacid chlorides followed by thermal cyclodehydration to PBO. A recent preparative route involves the reaction of aromatic bisphenols with bis(fluorophenyl) benzoxazoles by the displacement reaction to form PBO. The novelty of the present invention is that high molecular weight PBO of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

  8. Reducing Open Cell Landfill Methane Emissions with a Bioactive Alternative Daily

    SciTech Connect

    Helene Hilger; James Oliver; Jean Bogner; David Jones

    2009-03-31

    prone to rapid desiccation. Bacterial adsorption onto foam padding, natural sponge, and geotextile was successful. The most important factor for success appeared to be water holding capacity. Prototype biotarps made with geotextiles plus adsorbed methane oxidizing bacteria were tested for their responses to temperature, intermittent starvation, and washing (to simulate rainfall). The prototypes were mesophilic, and methane oxidation activity remained strong after one cycle of starvation but then declined with repeated cycles. Many of the cells detached with vigorous washing, but at least 30% appeared resistant to sloughing. While laboratory landfill simulations showed that four-layer composite biotarps made with two different types of geotextile could remove up to 50% of influent methane introduced at a flux rate of 22 g m{sup -2} d{sup -1}, field experiments did not yield high activity levels. Tests revealed that there were high hour-to-hour flux variations in the field, which, together with frequent rainfall events, confounded the field testing. Overall, the findings suggest that a methanotroph embedded biotarp appears to be a feasible strategy to mitigate methane emission from landfill cells, although the performance of field-tested biotarps was not robust here. Tarps will likely be best suited for spring and summer use, although the methane oxidizer population may be able to shift and adapt to lower temperatures. The starvation cycling of the tarp may require the capacity for intermittent reinoculation of the cells, although it is also possible that a subpopulation will adapt to the cycling and become dominant. Rainfall is not expected to be a major factor, because a baseline biofilm will be present to repopulate the tarp. If strong performance can be achieved and documented, the biotarp concept could be extended to include interception of other compounds beyond methane, such as volatile aromatic hydrocarbons and chlorinated solvents.

  9. Effects of Fault Displacement on Emplacement Drifts

    SciTech Connect

    F. Duan

    2000-04-25

    The purpose of this analysis is to evaluate potential effects of fault displacement on emplacement drifts, including drip shields and waste packages emplaced in emplacement drifts. The output from this analysis not only provides data for the evaluation of long-term drift stability but also supports the Engineered Barrier System (EBS) process model report (PMR) and Disruptive Events Report currently under development. The primary scope of this analysis includes (1) examining fault displacement effects in terms of induced stresses and displacements in the rock mass surrounding an emplacement drift and (2 ) predicting fault displacement effects on the drip shield and waste package. The magnitude of the fault displacement analyzed in this analysis bounds the mean fault displacement corresponding to an annual frequency of exceedance of 10{sup -5} adopted for the preclosure period of the repository and also supports the postclosure performance assessment. This analysis is performed following the development plan prepared for analyzing effects of fault displacement on emplacement drifts (CRWMS M&O 2000). The analysis will begin with the identification and preparation of requirements, criteria, and inputs. A literature survey on accommodating fault displacements encountered in underground structures such as buried oil and gas pipelines will be conducted. For a given fault displacement, the least favorable scenario in term of the spatial relation of a fault to an emplacement drift is chosen, and the analysis is then performed analytically. Based on the analysis results, conclusions are made regarding the effects and consequences of fault displacement on emplacement drifts. Specifically, the analysis will discuss loads which can be induced by fault displacement on emplacement drifts, drip shield and/or waste packages during the time period of postclosure.

  10. Growth and Dissolution of Calcite in the Presence of Adsorbed Stearic Acid.

    PubMed

    Ricci, Maria; Segura, Juan José; Erickson, Blake W; Fantner, Georg; Stellacci, Francesco; Voïtchovsky, Kislon

    2015-07-14

    The interaction of organic molecules with the surface of calcite plays a central role in many geochemical, petrochemical, and industrial processes and in biomineralization. Adsorbed organics, typically fatty acids, can interfere with the evolution of calcite when immersed in aqueous solutions. Here we use atomic force microscopy in liquid to explore in real-time the evolution of the (1014) surface of calcite covered with various densities of stearic acid and exposed to different saline solutions. Our results show that the stearic acid molecules tend to act as "pinning points" on the calcite's surface and slow down the crystal's restructuring kinetics. Depending on the amount of material adsorbed, the organic molecules can form monolayers or bilayer islands that become embedded into the growing crystal. The growth process can also displaces the organic molecules and actively concentrate them into stacked multilayers. Our results provide molecular-level insights into the interplay between the adsorbed fatty acid molecules and the evolving calcite crystal, highlighting mechanisms that could have important implications for several biochemical and geochemical processes and for the oil industry.

  11. Structural relaxation of an adlayer in presence of adsorbate-induced reconstruction: C_60/Cu(111)

    NASA Astrophysics Data System (ADS)

    Pai, Woei Wu; Hsu, C. L.; Lin, M. C.; Lin, K. C.

    2004-03-01

    We revisit submonolayer growth of C_60 on Cu(111) by STM, with emphasis on the formation of higher-order commensurate metastable states. These phases show concomitant interfacial reconstruction, adlayer buckling, and adlayer rotation to match to the 10.0 ÅC_60 nearest neighbor (NN) distance. Most interestingly, a clear correlation between the adlayer rotation angle and molecular contrast patterns is demonstrated. This is caused by the C_60-induced reconstruction at preferred binding sites and adlayer buckling in adjustment to strain. Four contrast patterns, i.e., ''disordered-maze'', ''linear-wall-maze'', ''p(√7 × √7)'', and ''p (2 × 2)'', with increasing C_60 NN distances are categorized. In the most compressed phase, buckling is favored and it is analogous to the ground state of an antiferromagnetic system on a triangular lattice with alike adlayer buckling and interfacial corrugation. In contrast, the molecular orderings in the other structures are mostly dictated by lateral displacements of C_60 toward preferred reconstructive binding sites. These phases thus illustrate structural relaxation of a molecular layer on an adsobate-induced reconstructed substrate in different adsorbate-adsorbate and adsorbate-substrate interaction limits.

  12. Untangleing the effects of chain rigidity on the structure and dynamics of strongly adsorbed polymer melts

    SciTech Connect

    Carrillo, Jan-Michael Y.; Cheng, Shiwang; Kumar, Rajeev; Goswami, Monojoy; Sokolov, Alexei P; Sumpter, Bobby G.

    2015-06-11

    Here, we present a detailed analysis of coarse-grained molecular dynamics simulations of semiflexible polymer melts in contact with a strongly adsorbing substrate. We have characterized the segments in the interfacial layer by counting the number of trains, loops, tails and unadsorbed segments. For more rigid chains, a tail and an adsorbed segment (a train) dominate while loops are more prevalent in more flexible chains. The tails exhibit a non-uniformly stretched conformation akin to the polydispersed pseudobrush envisioned by Guiselin. To probe the dynamics of the segments we computed the layer z-resolved intermediate coherent collective dynamics structure factor, S(q, t, z), mean-square displacement of segments, and the 2nd Legendre polynomial of the time-autocorrelation of unit bond vectors, 2[ni(t,z)•ni(0,z)]>. Our results show that segmental dynamics is slower for stiffer chains and there is a strong correlation between the structure and dynamics in the interfacial layer. There is no glassy layer, and the slowing down in dynamics of stiffer chains in the adsorbed region can be attributed to the densification and the more persistent layering of segments.

  13. Untangleing the effects of chain rigidity on the structure and dynamics of strongly adsorbed polymer melts

    DOE PAGES

    Carrillo, Jan-Michael Y.; Cheng, Shiwang; Kumar, Rajeev; Goswami, Monojoy; Sokolov, Alexei P; Sumpter, Bobby G.

    2015-06-11

    Here, we present a detailed analysis of coarse-grained molecular dynamics simulations of semiflexible polymer melts in contact with a strongly adsorbing substrate. We have characterized the segments in the interfacial layer by counting the number of trains, loops, tails and unadsorbed segments. For more rigid chains, a tail and an adsorbed segment (a train) dominate while loops are more prevalent in more flexible chains. The tails exhibit a non-uniformly stretched conformation akin to the polydispersed pseudobrush envisioned by Guiselin. To probe the dynamics of the segments we computed the layer z-resolved intermediate coherent collective dynamics structure factor, S(q, t, z),more » mean-square displacement of segments, and the 2nd Legendre polynomial of the time-autocorrelation of unit bond vectors, 2[ni(t,z)•ni(0,z)]>. Our results show that segmental dynamics is slower for stiffer chains and there is a strong correlation between the structure and dynamics in the interfacial layer. There is no glassy layer, and the slowing down in dynamics of stiffer chains in the adsorbed region can be attributed to the densification and the more persistent layering of segments.« less

  14. Archaebacterial Fuel Production: Methane from Biomass.

    ERIC Educational Resources Information Center

    Lennox, John E.; And Others

    1983-01-01

    Discusses microbial production of methane from biomass. Topics include methogens (bacteria producing methane), ecology of methanogenesis, methanogenesis in ruminant/nonruminant and other environments, role of methanogenesis in nature, and methane production in sewage treatment plants. Also discusses construction of methane digesters (and related…

  15. 75 FR 9886 - Methane Hydrate Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-04

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Methane... meeting. SUMMARY: This notice announces a meeting of the Methane Hydrate Advisory Committee. Federal... Methane Hydrate Advisory Committee is to provide advice on potential applications of methane hydrate...

  16. Oceanic Methane Concentrations in Three Mexican Regions

    EPA Science Inventory

    The atmospheric concentration of methane has increased significantly over the last several decades. Methane is an important greenhouse gas, and it is important to better quantify methane sources and sinks. Dissolved methane in the ocean is produced by biological and hydrothermal ...

  17. Solid state 13C NMR studies of methane dehydroaromatization reaction on Mo/HZSM-5 and W/HZSM-5 catalysts.

    PubMed

    Yang, Jun; Ma, Ding; Deng, Feng; Luo, Qing; Zhang, Mingjin; Bao, Xinhe; Ye, Chaohui

    2002-12-21

    Methane dehydroaromatization on Mo/HZSM-5 and W/HZSM-5 catalysts was studied by solid state 13C NMR spectroscopy, both variation of the state of transition metal component and products such as ethane, benzene, ethene adsorbed on or in zeolite were observed after high temperature (900-1000 K) reaction.

  18. (Methane digester). Final report

    SciTech Connect

    Waybright, R.C.

    1981-01-01

    The purpose of the grant was to construct and operate a methane digester for dairy manure involving the latest state-of-the-art technics. The first step taken was to empty out the existing digester to evaluate its performance and to gain ideas of how to build the next digester so it would operate more efficiently. Next, the design criteria was set up in order to eliminate some problems involved with the first digester and also new ideas as to how to build the next one without a protective building and testing simplified construction technics. After this the digester construction was started with the completion date in late January. The digester was then filled and operated at different temperatures attempting to achieve the optimum operating range.

  19. Adsorption-induced coal swelling and stress: Implications for methane production and acid gas sequestration into coal seams

    NASA Astrophysics Data System (ADS)

    Cui, Xiaojun; Bustin, R. Marc; Chikatamarla, Laxmi

    2007-10-01

    Sequestration of CO2 and H2S into deep unminable coal seams is an attractive option to reduce their emission into atmosphere and at the same time displace preadsorbed CH4 which is a clean energy resource. High coal seam permeability is required for efficient and practical sequestration of CO2 and H2S and recovery of CH4. However, adsorption of CO2 and H2S into coals induces strong swelling of the coal matrix (volumetric strain) and thus reduces significantly coal permeability by narrowing and even closing fracture apertures. Our experimental data on three western Canadian coals show that the adsorption-induced volumetric strain is approximately linearly proportional to the volume of adsorbed gas, and for the same gas, different coals have very similar volumetric strain coefficient. Impacts of adsorption-induced swelling on stress and permeability around wellbores were analytically investigated using our developed stress and permeability models. Our model results indicate that adsorption-induced volumetric strain has significant controls on stress and permeability of producing and sequestrating coal seams and consequently the potential of acid gas sequestration. Coal seams may undergo >10 times enhancement of permeability around CH4-producing wellbores due to a reduction in effective stress as a result of coal shrinking caused by methane desorption accompanying a reduction in reservoir pressure. Injection of H2S and CO2 on the other hand results in strong sorption-induced swelling and a marked increase in effective stress which in turn leads to a reduction of coal seam permeability of up to several orders of magnitude. Injection of mixtures of N2 and CO2 such as found in flue gas results in weaker swelling, the amount of which varies with gas composition, and provides the greatest opportunity of sequestering CO2 and secondary recovery of CH4 for most coals. Because of the marked swelling of coal in the presence of H2S, even minor amounts of H2S result in a marked

  20. Large methane reserves beneath Antarctica?

    NASA Astrophysics Data System (ADS)

    Wadham, J. L.; Tulaczyk, S. M.; Stibal, M.; Arndt, S.; Telling, J.; Lis, G.; Lawson, E. C.; Dubnick, A.; Tranter, M.; Sharp, M. J.; Anesio, A.

    2010-12-01

    Once thought to be devoid of life, the Antarctic Ice Sheet is now known to be a dynamic reservoir of metabolically active microbial cells and organic carbon. Its potential to support the degradation of organic carbon to methane, however, has not yet been evaluated. Large marine sedimentary basins beneath the ice sheet (estimated to cover up to 50% by area and contain sedimentary sequences up to 3 km thick) remain thawed during glaciation. These basins are estimated to contain ~7000 Pg of organic carbon, assuming that sedimentary basins account for 1 and 2 M km2 of the West and East Antarctic Ice Sheets respectively, the organic carbon content of overridden marine sediments is 0.5 % and the mean sediment depth is 1 km. We predict that this carbon is microbially cycled to methane under anoxic conditions beneath the ice sheet. Laboratory experimental data are consistent with this and show that organic carbon overridden by glaciers and ice sheets produces methane under anoxic conditions, and at rates similar to those observed in sub-seafloor sediments. We numerically model the accumulation of methane in Antarctic sedimentary basins and show that sediment porewaters become over-saturated with methane over >1 Myr and that typical pressure/temperature conditions favour methane hydrate formation down to between ~500m and ~1000m in the sedimentary column. We calculate conservatively that a minimum of ~70 and ~360 PgC of releasable methane (clathrate + free gas) could be produced beneath the West and East Antarctic Ice Sheets over 3 and 30 Myr of glaciation respectively, which is of a similar order of magnitude to methane present as hydrate in Arctic permafrost. The stability of this releasable methane reserve depends sensitively upon in situ pressure conditions, and hence ice thickness. We show that only modest ice sheet retreat rates (700-2000 km2 a-1) are required to stimulate out gassing of releasable methane from Antarctic sedimentary basins at rates sufficient to

  1. Phase behavior of methane haze.

    PubMed

    Signorell, R; Jetzki, M

    2007-01-01

    Methane aerosols play a fundamental role in the atmospheres of Neptune, Uranus, and Saturn's moon Titan as borne out by the recent Cassini-Huygens mission. Here we present the first study of the phase behavior of free methane aerosol particles combining collisional cooling with rapid-scan infrared spectroscopy in situ. We find fast (within minutes) phase transitions to crystalline states directly after particle formation and characteristic surface effects for nanometer-sized particles. From our results, we conclude that in atmospheric clouds solid methane particles are crystalline.

  2. Phase behavior of methane haze.

    PubMed

    Signorell, R; Jetzki, M

    2007-01-01

    Methane aerosols play a fundamental role in the atmospheres of Neptune, Uranus, and Saturn's moon Titan as borne out by the recent Cassini-Huygens mission. Here we present the first study of the phase behavior of free methane aerosol particles combining collisional cooling with rapid-scan infrared spectroscopy in situ. We find fast (within minutes) phase transitions to crystalline states directly after particle formation and characteristic surface effects for nanometer-sized particles. From our results, we conclude that in atmospheric clouds solid methane particles are crystalline. PMID:17358473

  3. Displaced Homemakers: Vo-Tech Workshop Guide.

    ERIC Educational Resources Information Center

    Peltier, Wanda Jo

    Written for displaced homemaker programs in vocational-technical schools, this curriculum contains material designed so that instructors can prepare student manuals appropriate to almost any educational support situation for displaced homemakers. An overview provides information on special needs groups, curriculum use, and resources and sample…

  4. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Engine displacement. 205.153 Section 205.153 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a)...

  5. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Engine displacement. 205.153 Section 205.153 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a)...

  6. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Engine displacement. 205.153 Section 205.153 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a)...

  7. Video Games, Adolescents, and the Displacement Effect

    ERIC Educational Resources Information Center

    Fisher, Carla Christine

    2012-01-01

    The displacement effect (the idea that time spent in one activity displaces time spent in other activities) was examined within the lens of adolescents' video game use and their time spent reading, doing homework, in physically active sports and activities, in creative play, and with parents and friends. Data were drawn from the Panel Study…

  8. 20 CFR 211.8 - Displacement allowance.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false Displacement allowance. 211.8 Section 211.8 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee because he has...

  9. 20 CFR 211.8 - Displacement allowance.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true Displacement allowance. 211.8 Section 211.8 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee because he has...

  10. 20 CFR 211.8 - Displacement allowance.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Displacement allowance. 211.8 Section 211.8 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee because he has...

  11. 20 CFR 211.8 - Displacement allowance.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false Displacement allowance. 211.8 Section 211.8 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee because he has...

  12. 20 CFR 211.8 - Displacement allowance.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true Displacement allowance. 211.8 Section 211.8 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee because he has...

  13. Controlling adsorbate interactions for advanced chemical patterning

    NASA Astrophysics Data System (ADS)

    Saavedra Garcia, Hector M.

    Molecules designed to have specific interactions were used to influence the structural, physical, and chemical properties of self-assembled monolayers. In the case of 1-adamantanethiolate monolayers, the molecular structure influences lability, enabling alkanethiol molecules in solution to displace the 1-adamantanethiolate monolayers, ultimately leading to complete molecular exchange. The similar Au-S bond environments measured for both n-alkanethiolate and 1-adamantanethiolate monolayers indicate that displacement is not a result of weakened Au-S bonds. Instead, it was hypothesized that the density differences in the two monolayers provide a substantial enthalpic driver, aided by differences in van der Waals forces, ultimately leading to complete displacement of the 1-adamantenthiol molecules. Additionally, it was discovered that displacement occurs via fast insertion of n-dodecanethiolate at the defects in the original 1-adamantanethiolate monolayer, which nucleates an island growth phase and is followed by slow ordering of the n-dodecanethiolate domains into a denser and more crystalline form. Langmuir-based kinetics, which describe alkanethiolate adsorption on bare Au{111}, fail to model this displacement reaction. Instead, a model of perimeter-dependent island growth yields good agreement with kinetic data over a 100-fold variation in n-dodecanethiol concentration. Rescaling the growth rate at each concentration collapses all the data onto a single universal curve, suggesting that displacement is a scale-free process. Exploiting the knowledge gained by studying 1-adamantethiolate monolayer displacement, a reversible molecular resist was developed, in which displacement is controlled via external stimuli. This methodology for the fabrication of controllably displaceable monolayers relies on carboxyl-functionalized self-assembled monolayers and in-situ Fischer esterification. Using an 11-mercaptoundecanoic acid monolayer as a model system, it was shown that in

  14. Determining Methane Leak Locations and Rates with a Wireless Network Composed of Low-Cost, Printed Sensors

    NASA Astrophysics Data System (ADS)

    Smith, C. J.; Kim, B.; Zhang, Y.; Ng, T. N.; Beck, V.; Ganguli, A.; Saha, B.; Daniel, G.; Lee, J.; Whiting, G.; Meyyappan, M.; Schwartz, D. E.

    2015-12-01

    We will present our progress on the development of a wireless sensor network that will determine the source and rate of detected methane leaks. The targeted leak detection threshold is 2 g/min with a rate estimation error of 20% and localization error of 1 m within an outdoor area of 100 m2. The network itself is composed of low-cost, high-performance sensor nodes based on printed nanomaterials with expected sensitivity below 1 ppmv methane. High sensitivity to methane is achieved by modifying high surface-area-to-volume-ratio single-walled carbon nanotubes (SWNTs) with materials that adsorb methane molecules. Because the modified SWNTs are not perfectly selective to methane, the sensor nodes contain arrays of variously-modified SWNTs to build diversity of response towards gases with adsorption affinity. Methane selectivity is achieved through advanced pattern-matching algorithms of the array's ensemble response. The system is low power and designed to operate for a year on a single small battery. The SWNT sensing elements consume only microwatts. The largest power consumer is the wireless communication, which provides robust, real-time measurement data. Methane leak localization and rate estimation will be performed by machine-learning algorithms built with the aid of computational fluid dynamics simulations of gas plume formation. This sensor system can be broadly applied at gas wells, distribution systems, refineries, and other downstream facilities. It also can be utilized for industrial and residential safety applications, and adapted to other gases and gas combinations.

  15. Global Methane Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Reeburgh, W. S.

    2003-12-01

    Methane (CH4) has been studied as an atmospheric constituent for over 200 years. A 1776 letter from Alessandro Volta to Father Campi described the first experiments on flammable "air" released by shallow sediments in Lake Maggiore (Wolfe, 1996; King, 1992). The first quantitative measurements of CH4, both involving combustion and gravimetric determination of trapped oxidation products, were reported in French by Boussingault and Boussingault, 1864 and Gautier (1901), who reported CH4 concentrations of 10 ppmv and 0.28 ppmv (seashore) and 95 ppmv (Paris), respectively. The first modern measurements of atmospheric CH4 were the infrared absorption measurements of Migeotte (1948), who estimated an atmospheric concentration of 2.0 ppmv. Development of gas chromatography and the flame ionization detector in the 1950s led to observations of vertical CH4 distributions in the troposphere and stratosphere, and to establishment of time-series sampling programs in the late 1970s. Results from these sampling programs led to suggestions that the concentration of CH4, as that of CO2, was increasing in the atmosphere. The possible role of CH4 as a greenhouse gas stimulated further research on CH4 sources and sinks. Methane has also been of interest to microbiologists, but findings from microbiology have entered the larger context of the global CH4 budget only recently.Methane is the most abundant hydrocarbon in the atmosphere. It plays important roles in atmospheric chemistry and the radiative balance of the Earth. Stratospheric oxidation of CH4 provides a means of introducing water vapor above the tropopause. Methane reacts with atomic chlorine in the stratosphere, forming HCl, a reservoir species for chlorine. Some 90% of the CH4 entering the atmosphere is oxidized through reactions initiated by the OH radical. These reactions are discussed in more detail by Wofsy (1976) and Cicerone and Oremland (1988), and are important in controlling the oxidation state of the atmosphere

  16. Resources assessment of methane hydrates offshore Japan

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.

    2015-12-01

    JOGMEC, as a member of research group for resources assessment of Research Consortium for Methane Hydrate Resources in Japan (MH21), is conducting resources assessment of methane hydrates (MHs) offshore surrounding Japan. The interpretation of 3-D seismic data acquired by geophysical vessel 'Shigen', which is owned by Agency for Natural Resources and Energy, are carried out. And MH concentrated zones are being extracted. This study is an introduction for the case example of interpretation of 3-D seismic data in the area which have not been drilled. The characteristic of 3-D seismic data in this study area shows fold structure, which undulates severalfold. In addition, some faults are interpreted, which does not show the large displacement, are seen. Bottom Simulating Reflector (BSR) is very visible continuously. Clear velocity contrast in the boundary between above and below of BSR and the high velocity anomaly above BSR are confirmed in the high density velocity analysis profile. MHs are assumed to exist in sand heterogeneously because the velocity distribution in the extracted zones is inhomogeneous. In the results of geomorphological analysis, channel deposits and mid submarine fan deposits, which are located above BSR, are presumed the sediments which bear sand. Thus the extracted zones are estimated MH concentrated zones. As above, even the area has not been drilled, the extraction of MH concentrated zones can be estimated by the interpretation of the seismic data, the result of the high density velocity analysis, and the distribution of sand by geomorphological analysis. These results will be useful for the plan of the future drilling programme. This introduction is the example of 3-D seismic survey area. It will become a useful information for 3-D seismic survey plan by performing similar interpretation in 2-D seismic survey lines.

  17. Improving biogas separation and methane storage with multilayer graphene nanostructure via layer spacing optimization and lithium doping: a molecular simulation investigation.

    PubMed

    Chen, Jie-Jie; Li, Wen-Wei; Li, Xue-Liang; Yu, Han-Qing

    2012-09-18

    Methane is a desirable alternative to conventional fossil fuels, and also a main component of biogas from anaerobic fermentation of organic wastes. However, its relatively lower purity and poor storage by existing adsorbent materials negatively affect its wide application. Thus, efficient, cost-effective, and safe adsorbent materials for methane purification and storage are highly desired. In this study, multilayer graphene nanostructures (MGNs) with optimized structure are investigated as a potential adsorbent for this purpose. The effects of layer distance and Li doping on MGN performance in terms of methane storage and acid gas (H(2)S and CO(2)) separation from biogas are examined by molecular simulations. The mechanisms for the interactions between gas molecules and substrates are elucidated by analyzing the binding energy, geometric structures, and charge distribution from the first-principles calculations. The results show that nonhydrocarbons in biogas can be effectively separated using Li-doped MGNs with the optimal layer distance of 0.68 nm, and then the pure methane gas can be stored in MGNs with capacity satisfying the DOE target. This work offers a molecular-level insight into the interactions between gas molecules and MGNs and might provide useful information for development of new materials for methane purification and storage.

  18. Using a 2D displacement sensor to derive 3D displacement information

    NASA Technical Reports Server (NTRS)

    Soares, Schubert F. (Inventor)

    2002-01-01

    A 2D displacement sensor is used to measure displacement in three dimensions. For example, the sensor can be used in conjunction with a pulse-modulated or frequency-modulated laser beam to measure displacement caused by deformation of an antenna on which the sensor is mounted.

  19. Simulations of threshold displacement in beryllium

    NASA Astrophysics Data System (ADS)

    Jackson, Matthew L.; Fossati, Paul C. M.; Grimes, Robin W.

    2016-07-01

    Atomic scale molecular dynamics simulations of radiation damage have been performed on beryllium. Direct threshold displacement simulations along a geodesic projection of directions were used to investigate the directional dependence with a high spatial resolution. It was found that the directionally averaged probability of displacement increases from 0 at 35 eV, with the energy at which there is a 50% chance of a displacement occurring is 70 eV and asymptotically approaching 1 for higher energies. This is, however, strongly directionally dependent with a 50% probability of displacement varying from 35 to 120 eV, with low energy directions corresponding to the nearest neighbour directions. A new kinetic energy dependent expression for the average maximum displacement of an atom as a function of energy is derived which closely matches the simulated data.

  20. Changes of biogeochemical activities before and after significant mud displacement at the Håkon Mosby Mud Volcano (HMMV)

    NASA Astrophysics Data System (ADS)

    Felden, J.; Wenzhöfer, F.; Yoerger, D.; Camilli, R.; German, C.; Olu, K.; Feseker, T.; de Beer, D.; Boetius, A.

    2012-04-01

    The Håkon Mosby Mud Volcano (72°N, 14° 43' E, 1250 m water depth) was studied for a period of a year by the Long-term Observatory On Mud-volcano Eruptions (LOOME) in 2009-2010, to investigate temporal variations of mud volcanism and consequences for biogeochemical processes. The HMMV is a highly active methane cold seep ecosystem characterized by high rates of methane efflux. It hosts different chemosynthetic communities such as thiotrophic bacterial mats and siboglinid tubeworm assemblages. This study focuses on changes in community composition and biogeochemical activity such as methane emission, total benthic oxygen uptake, microbial methane and sulfate consumption before and after a major mud displacement recorded by LOOME. The sensor-enabled long-term observations of the HMMV habitats were combined with short-term analyses before and after the displacement events by ROVs QUEST (MARUM) and GENESIS (University of Gent), the AUV Sentry (WHOI) equipped with a multibeam and subbottom profiler, CTD and photographic unit as well as with a mass spectrometer. We found shifts in the distribution patterns of chemosynthetic communities and also substantial changes in their activity, consistent with changes in temperature gradients. This study was sponsored by the EU-Projects HERMIONE "Hotspot Ecosystem Research and Man's Impact on European Seas", and ESONET "European Seas Observatory Network" (Demonstration Mission LOOME "Long term observations on mud volcano eruptions").

  1. Quasielastic electron scattering from methane, methane-d4, methane-d2, ethylene, and 2-methylpropane

    NASA Astrophysics Data System (ADS)

    Cooper, G.; Christensen, E.; Hitchcock, A. P.

    2007-08-01

    Quasielastic electron scattering from gaseous species at high momentum transfer was recently reported for the first time [Cooper et al., J. Electron Spectrosc. Relat. Phenom. 155, 28 (2007)]. The first results for CH4 and CD4 were well explained by a classical electron Compton scattering picture in which the electron scatters independently from each atom rather than the molecule as a whole. However, an alternative possible interpretation in terms of nondipole molecular vibrational excitation is suggested by previously published quantum mechanical calculations on high momentum transfer electron scattering from diatomic molecules [Bonham and de Souza, J. Chem. Phys. 79, 134 (1983)]. In order to determine which of these two interpretations best fits the experimental results, we have measured the quasielastic spectra of gaseous 2-methylpropane, ethylene, methane, and two isotopically substituted methanes, CH2D2 and CD4, at a momentum transfer of ˜20a.u. (2.25keV impact energy and 100° scattering angle). The experimental spectra are found to be composed of as many peaks as there are different atomic isotopes in the molecule (two for CH4, C2H4, 2-methylpropane, and CD4 and three for CH2D2). The peak positions are predicted accurately by the independent atom electron Compton scattering model, and the relative intensities are in reasonable agreement. The experimental results thus support classical electron Compton scattering as the origin of the signal.

  2. Methane production in terrestrial arthropods

    SciTech Connect

    Hackstein, J.H.P.; Stumm, C.K. )

    1994-06-07

    The authors have screened more than 110 representatives of the different taxa of terrestrial arthropods for methane production in order to obtain additional information about the origins of biogenic methane. Methanogenic bacteria occur in the hindguts of nearly all tropical representatives of millipedes (Diplopoda), cockroaches (Blattaria), termites (Isoptera), and scarab beetles (Scarabaeidae), while such methanogens are absent from 66 other arthropod species investigated. Three types of symbiosis were found: in the first type, the arthropod's hindgut is colonized by free methanogenic bacteria; in the second type, methanogens are closely associated with chitinous structures formed by the host's hindgut; the third type is mediated by intestinal anaerobic protists with intracellular methanogens. Such symbiotic associations are likely to be a characteristic property of the particular taxon. Since these taxa represent many families with thousands of species, the world populations of methane-producing arthropods constitute an enormous biomass. The authors show that arthropod symbionts can contribute substantially to atmospheric methane.

  3. Methane production in terrestrial arthropods.

    PubMed

    Hackstein, J H; Stumm, C K

    1994-06-01

    We have screened more than 110 representatives of the different taxa of terrestrial arthropods for methane production in order to obtain additional information about the origins of biogenic methane. Methanogenic bacteria occur in the hindguts of nearly all tropical representatives of millipedes (Diplopoda), cockroaches (Blattaria), termites (Isoptera), and scarab beetles (Scarabaeidae), while such methanogens are absent from 66 other arthropod species investigated. Three types of symbiosis were found: in the first type, the arthropod's hindgut is colonized by free methanogenic bacteria; in the second type, methanogens are closely associated with chitinous structures formed by the host's hindgut; the third type is mediated by intestinal anaerobic protists with intracellular methanogens. Such symbiotic associations are likely to be a characteristic property of the particular taxon. Since these taxa represent many families with thousands of species, the world populations of methane-producing arthropods constitute an enormous biomass. We show that arthropod symbionts can contribute substantially to atmospheric methane.

  4. Methane production in terrestrial arthropods.

    PubMed Central

    Hackstein, J H; Stumm, C K

    1994-01-01

    We have screened more than 110 representatives of the different taxa of terrestrial arthropods for methane production in order to obtain additional information about the origins of biogenic methane. Methanogenic bacteria occur in the hindguts of nearly all tropical representatives of millipedes (Diplopoda), cockroaches (Blattaria), termites (Isoptera), and scarab beetles (Scarabaeidae), while such methanogens are absent from 66 other arthropod species investigated. Three types of symbiosis were found: in the first type, the arthropod's hindgut is colonized by free methanogenic bacteria; in the second type, methanogens are closely associated with chitinous structures formed by the host's hindgut; the third type is mediated by intestinal anaerobic protists with intracellular methanogens. Such symbiotic associations are likely to be a characteristic property of the particular taxon. Since these taxa represent many families with thousands of species, the world populations of methane-producing arthropods constitute an enormous biomass. We show that arthropod symbionts can contribute substantially to atmospheric methane. Images PMID:8202505

  5. Methane emissions from MBT landfills

    SciTech Connect

    Heyer, K.-U. Hupe, K.; Stegmann, R.

    2013-09-15

    Highlights: • Compilation of methane generation potential of mechanical biological treated (MBT) municipal solid waste. • Impacts and kinetics of landfill gas production of MBT landfills, approach with differentiated half-lives. • Methane oxidation in the waste itself and in soil covers. • Estimation of methane emissions from MBT landfills in Germany. - Abstract: Within the scope of an investigation for the German Federal Environment Agency (“Umweltbundesamt”), the basics for the estimation of the methane emissions from the landfilling of mechanically and biologically treated waste (MBT) were developed. For this purpose, topical research including monitoring results regarding the gas balance at MBT landfills was evaluated. For waste treated to the required German standards, a methane formation potential of approximately 18–24 m{sup 3} CH{sub 4}/t of total dry solids may be expected. Monitoring results from MBT landfills show that a three-phase model with differentiated half-lives describes the degradation kinetics in the best way. This is due to the fact that during the first years of disposal, the anaerobic degradation processes still proceed relatively intensively. In addition in the long term (decades), a residual gas production at a low level is still to be expected. Most of the soils used in recultivation layer systems at German landfills show a relatively high methane oxidation capacity up to 5 l CH{sub 4}/(m{sup 2} h). However, measurements at MBT disposal sites indicate that the majority of the landfill gas (in particular at non-covered areas), leaves the landfill body via preferred gas emission zones (hot spots) without significant methane oxidation. Therefore, rather low methane oxidation factors are recommended for open and temporarily covered MBT landfills. Higher methane oxidation rates can be achieved when the soil/recultivation layer is adequately designed and operated. Based on the elaborated default values, the First Order Decay (FOD

  6. Methane generation from animal wastes

    SciTech Connect

    Fulton, E.L.

    1980-06-01

    The conversion of manure to biogas via anaerobic digestion is described. The effluent resulting from the conversion retains fertilizer value and is environmentally acceptable. Discussion is presented under the headings: methane formation in the digester; the Tarleton State Poultry Waste to Methane production system; operating experience at Tarleton State; economics of biogas production from poultry waste; construction cost and biogas value; energy uses; feed and waste processing; and advantages of anaerobic digestion. (DMC)

  7. Recovery of Technetium Adsorbed on Charcoal

    SciTech Connect

    Engelmann, Mark D.; Metz, Lori A.; Ballou, Nathan E.

    2006-05-01

    Two methods capable of near complete recovery of technetium adsorbed on charcoal are presented. The first involves liquid extraction of the technetium from the charcoal by hot 4M nitric acid. An average recovery of 98% (n=3) is obtained after three rounds of extraction. The second method involves dry ashing with air in a quartz combustion tube at 400-450 C. This method yields an average recovery of 96% (n=5). Other thermal methods were attempted, but resulted in reduced recovery and incomplete material balance

  8. Conformational properties of an adsorbed charged polymer.

    PubMed

    Cheng, Chi-Ho; Lai, Pik-Yin

    2005-06-01

    The behavior of a strongly charged polymer adsorbed on an oppositely charged surface of a low-dielectric constant is formulated by the functional integral method. By separating the translational, conformational, and fluctuational degrees of freedom, the scaling behaviors for both the height of the polymer and the thickness of the diffusion layer are determined. Unlike the results predicted by scaling theory, we identified the continuous crossover from the weak compression to the compression regime. All the analytical results are found to be consistent with Monte Carlo simulations. Finally, an alternative (operational) definition of a charged polymer adsorption is proposed. PMID:16089715

  9. Methane production in Minnesota peatlands

    SciTech Connect

    Williams, R.T.; Crawford, R.L.

    1984-06-01

    Rates of methane production in Minnesota peats were studied. Surface (10- to 25-cm) peats produced an average of 228 nmol of CH/sub 4/ per g (dry weight) per h at 25/sup 0/C and ambient pH. Methanogenesis rates generally decreased with depth in ombrotrophic peats, but on occasion were observed to rise within deeper layers of certain fen peats. Methane production was temperature dependent, increasing with increasing temperature (4 to 30/sup 0/C), except in peats from deeper layers. Maximal methanogenesis from these deeper regions occurred at 12/sup 0/C. Methane production rates were also pH dependent. Two peats with pHs of 3.8 and 4.3 had an optimum rate of methane production at pH 6.0. The addition to peat of glucose and H/sub 2/-CO/sub 2/ stimulated methanogenesis, whereas the addition of acetate inhibited methanogenesis. Cysteine-sulfide, nitrogen-phosphorus-trace metals, and vitamins-yeast extract affected methane production very little. Various gases were found to be trapped or dissolved (or both) within peatland waters. Dissolved methane increased linearly to a depth of 210 cm. The accumulation of metabolic end products produced within peat bogs appears to be an important mechanism limiting turnover in peatland environments.

  10. Optical constants of solid methane

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N.; Thompson, W. R.; Sagan, C.; Arakawa, E. T.; Bruel, C.; Judish, J. P.; Khanna, R. K.; Pollack, J. B.

    1989-01-01

    Methane is the most abundant simple organic molecule in the outer solar system bodies. In addition to being a gaseous constituent of the atmospheres of the Jovian planets and Titan, it is present in the solid form as a constituent of icy surfaces such as those of Triton and Pluto, and as cloud condensate in the atmospheres of Titan, Uranus, and Neptune. It is expected in the liquid form as a constituent of the ocean of Titan. Cometary ices also contain solid methane. The optical constants for both solid and liquid phases of CH4 for a wide temperature range are needed for radiative transfer calculations, for studies of reflection from surfaces, and for modeling of emission in the far infrared and microwave regions. The astronomically important visual to near infrared measurements of solid methane optical constants are conspicuously absent from the literature. Preliminary results are presented of the optical constants of solid methane for the 0.4 to 2.6 micron region. K is reported for both the amorphous and the crystalline (annealed) states. Using the previously measured values of the real part of the refractive index, n, of liquid methane at 110 K n is computed for solid methane using the Lorentz-Lorentz relationship. Work is in progress to extend the measurements of optical constants n and k for liquid and solid to both shorter and longer wavelengths, eventually providing a complete optical constants database for condensed CH4.

  11. Phase diagrams and capillarity condensation of methane confined in single- and multi-layer nanotubes

    NASA Astrophysics Data System (ADS)

    Ortiz, V.; López-Álvarez, Y. M.; López, G. E.

    Using a newly developed algorithm in the Gibbs ensemble, the liquid-vapour phase diagram of methane adsorbed in single and multilayer nanotubes was considered. The method was based on improving statistical sampling by combining the cavity-bias and the parallel tempering formalisms in Gibbs ensemble Monte Carlo simulations (PTCBGMC). Two models were constructed in order to describe the liquid-vapour equilibrium of methane in nanotubes. The first model consisted of two simulated nanotube-shaped boxes, one containing the vapour and the other containing the liquid. The vapour and liquid were kept in thermodynamic equilibrium using the PTCBGMC algorithm. Cailletet-Mathias phase diagrams showed that upon adsorption of methane in the nanotubes, the critical temperature and density of methane decreased upon confinement. However, the behaviour of the liquid and vapour phases differed depending on whether the nanotube was single- or multi-layered. A second computational model was used to consider in detail the capillarity condensation of methane in the nanotubes. The results obtained were explained in terms of the difference in the strength of the intermolecular forces.

  12. Electrochemical and partial oxidation of methane

    NASA Astrophysics Data System (ADS)

    Singh, Rahul

    2008-10-01

    negligible coke formation on the novel fabricated anode by electroless plating process. Hydrogen is an environmentally cleaner source of energy. The recent increase in the demand of hydrogen as fuel for all types of fuel cells and petroleum refining process has boosted the need of production of hydrogen. Methane, a major component of natural gas is the major feedstock for production of hydrogen. The route of partial oxidation of methane to produce syngas (CO + H2) offers significant advantages over commercialized steam reforming process for higher efficiency and lower energy requirements. Partial oxidation of methane was studied by pulsing O2 into a CH4 flow over Rh/Al2O3 in a sequence of in situ infrared (IR) cell and fixed bed reactor at 773 K. The results obtained from the sequence of an IR cell followed by a fixed bed reactor show that (i) adsorbed CO produced possesses a long residence time, indicating that adsorbed oxygen leading to the formation of CO is significantly different from those leading to CO2 and (ii) CO2 is not an intermediate species for the formation of CO. In situ IR of pulse reaction coupled with alternating reactor sequence is an effective approach to study the primary and secondary reactions as well as the nature of their adsorbed species. As reported earlier, hydrogen remains to be the most effective fuel for fuel cells, the production of high purity hydrogen from naturally available resources such as coal, petroleum, and natural gas requires a number of energy-intensive steps, making fuel cell processes for stationary electric power generation prohibitively uneconomic. Direct use of coal or coal gas as the feed is a promising approach for low cost electricity generation. Coal gas solid oxide fuel cell was studied by pyrolyzing Ohio #5 coal to coal gas and transporting to a Cu anode solid oxide fuel cell to generate power. The study of coal-gas solid oxide fuel cell is divided into two sections, i.e., (i) understanding the composition of coal gas by

  13. Variable displacement alpha-type Stirling engine

    NASA Astrophysics Data System (ADS)

    Homutescu, V. M.; Bălănescu, D. T.; Panaite, C. E.; Atanasiu, M. V.

    2016-08-01

    The basic design and construction of an alpha-type Stirling engine with on load variable displacement is presented. The variable displacement is obtained through a planar quadrilateral linkage with one on load movable ground link. The physico-mathematical model used for analyzing the variable displacement alpha-type Stirling engine behavior is an isothermal model that takes into account the real movement of the pistons. Performances and power adjustment capabilities of such alpha-type Stirling engine are calculated and analyzed. An exemplification through the use of the numerical simulation was performed in this regard.

  14. Is methane a new therapeutic gas?

    PubMed Central

    2012-01-01

    Background Methane is an attractive fuel. Biologically, methanogens in the colon can use carbon dioxide and hydrogen to produce methane as a by-product. It was previously considered that methane is not utilized by humans. However, in a recent study, results demonstrated that methane could exert anti-inflammatory effects in a dog small intestinal ischemia-reperfusion model. Point of view Actually, the bioactivity of methane has been investigated in gastrointestinal diseases, but the exact mechanism underlying the anti-inflammatory effects is required to be further elucidated. Methane can cross the membrane and is easy to collect due to its abundance in natural gas. Although methane is flammable, saline rich in methane can be prepared for clinical use. These seem to be good news in application of methane as a therapeutic gas. Conclusion Several problems should be resolved before its wide application in clinical practice. PMID:23009320

  15. Mimetite Formation from Goethite-Adsorbed Ions.

    PubMed

    Kleszczewska-Zębala, Anna; Manecki, Maciej; Bajda, Tomasz; Rakovan, John; Borkiewicz, Olaf J

    2016-06-01

    Bioavailability of arsenic in contaminated soils and wastes can be reduced to insignificant levels by precipitation of mimetite Pb5(AsO4)3Cl. The objective of this study is to elucidate mechanisms of the reaction between solution containing lead ions and arsenates adsorbed on synthetic goethite (AsO4-goethite), or arsenate ions in the solution and goethite saturated with adsorbed Pb (Pb-goethite). These reactions, in the presence of Cl, result in rapid crystallization of mimetite. Formation of mimetite is faster than desorption of AsO4 but slower than desorption of Pb from the goethite surface. Slow desorption of arsenates from AsO4-goethite results in heterogeneous precipitation and formation of mimetite incrustation on goethite crystals. Desorption of lead from Pb-goethite is at least as fast as diffusion and advection of AsO4 and Cl in suspension allowing for homogeneous crystallization of mimetite in intergranular solution. Therefore, the mechanism of nucleation is primarily driven by the kinetics of constituent supply to the saturation front, rather than by the thermodynamics of nucleation. The products of the reactions are well documented using microscopy methods such as scanning electron microscopy, electron backscattered diffraction, X-ray diffraction, and Fourier transform infrared spectroscopy.

  16. The persistence length of adsorbed dendronized polymers.

    PubMed

    Grebikova, Lucie; Kozhuharov, Svilen; Maroni, Plinio; Mikhaylov, Andrey; Dietler, Giovanni; Schlüter, A Dieter; Ullner, Magnus; Borkovec, Michal

    2016-07-21

    The persistence length of cationic dendronized polymers adsorbed onto oppositely charged substrates was studied by atomic force microscopy (AFM) and quantitative image analysis. One can find that a decrease in the ionic strength leads to an increase of the persistence length, but the nature of the substrate and of the generation of the side dendrons influence the persistence length substantially. The strongest effects as the ionic strength is being changed are observed for the fourth generation polymer adsorbed on mica, which is a hydrophilic and highly charged substrate. However, the observed dependence on the ionic strength is much weaker than the one predicted by the Odijk, Skolnik, and Fixman (OSF) theory for semi-flexible chains. Low-generation polymers show a variation with the ionic strength that resembles the one observed for simple and flexible polyelectrolytes in solution. For high-generation polymers, this dependence is weaker. Similar dependencies are found for silica and gold substrates. The observed behavior is probably caused by different extents of screening of the charged groups, which is modified by the polymer generation, and to a lesser extent, the nature of the substrate. For highly ordered pyrolytic graphite (HOPG), which is a hydrophobic and weakly charged substrate, the electrostatic contribution to the persistence length is much smaller. In the latter case, we suspect that specific interactions between the polymer and the substrate also play an important role. PMID:27353115

  17. Nitric oxide releasing material adsorbs more fibrinogen.

    PubMed

    Lantvit, Sarah M; Barrett, Brittany J; Reynolds, Melissa M

    2013-11-01

    One mechanism of the failure of blood-contacting devices is clotting. Nitric oxide (NO) releasing materials are seen as a viable solution to the mediation of surface clotting by preventing platelet activation; however, NO's involvement in preventing clot formation extends beyond controlling platelet function. In this study, we evaluate NO's effect on factor XII (fibrinogen) adsorption and activation, which causes the initiation of the intrinsic arm of the coagulation cascade. This is done by utilizing a model plasticized poly(vinyl) chloride (PVC), N-diazeniumdiolate system and looking at the adsorption of fibrinogen, an important clotting protein, to these surfaces. The materials have been prepared in such a way to eliminate changes in surface properties between the control (plasticized PVC) and composite (NO-releasing) materials. This allows us to isolate NO release and determine the effect on the adsorption of fibrinogen, to the material surface. Surprisingly, it was found that an NO releasing material with a surface flux of 17.4 ± 0.5 × 10(-10) mol NO cm(-2) min(-1) showed a significant increase in the amount of fibrinogen adsorbed to the material surface compared to one with a flux of 13.0 ± 1.6 × 10(-10) mol NO cm(-2) min(-1) and the control (2334 ± 496, 226 ± 99, and 103 ±31% fibrinogen adsorbed of control, respectively). This study suggests that NO's role in controlling clotting is extended beyond platelet activation. PMID:23554300

  18. Optimizing heterosurface adsorbent synthesis for liquid chromatography

    NASA Astrophysics Data System (ADS)

    Bogoslovskii, S. Yu.; Serdan, A. A.

    2016-03-01

    The structural and geometric parameters of a silica matrix (SM) for the synthesis of heterosurface adsorbents (HAs) are optimized. Modification is performed by shielding the external surfaces of alkyl-modified silica (AS) using human serum albumin and its subsequent crosslinking. The structural and geometric characteristics of the SM, AS, and HA are measured via low-temperature nitrogen adsorption. It is found that the structural characteristics of AS pores with diameters D < 6 nm do not change during HA synthesis, while the volume of pores with diameters of 6 nm < D < 9 nm shrinks slightly due to the adsorption of albumin in the pore orifices. It is established that the volume of pores with diameters D > 9 nm reduces significantly due to adsorption of albumin. It is concluded that silica gel with a maximum pore size distribution close to 5 nm and a minimal proportion of pores with D > 9 nm is optimal for HA synthesis; this allows us to achieve the greatest similarity between the chromatographic retention parameters for HA and AS. The suitability of the synthesized adsorbents for analyzing drugs in biological fluids through direct sample injection is confirmed by chromatography. It was found that the percentage of the protein fraction detected at the outlet of the chromatographic column is 98%.

  19. PDT - PARTICLE DISPLACEMENT TRACKING SOFTWARE

    NASA Technical Reports Server (NTRS)

    Wernet, M. P.

    1994-01-01

    Particle Imaging Velocimetry (PIV) is a quantitative velocity measurement technique for measuring instantaneous planar cross sections of a flow field. The technique offers very high precision (1%) directionally resolved velocity vector estimates, but its use has been limited by high equipment costs and complexity of operation. Particle Displacement Tracking (PDT) is an all-electronic PIV data acquisition and reduction procedure which is simple, fast, and easily implemented. The procedure uses a low power, continuous wave laser and a Charged Coupled Device (CCD) camera to electronically record the particle images. A frame grabber board in a PC is used for data acquisition and reduction processing. PDT eliminates the need for photographic processing, system costs are moderately low, and reduced data are available within seconds of acquisition. The technique results in velocity estimate accuracies on the order of 5%. The software is fully menu-driven from the acquisition to the reduction and analysis of the data. Options are available to acquire a single image or 5- or 25-field series of images separated in time by multiples of 1/60 second. The user may process each image, specifying its boundaries to remove unwanted glare from the periphery and adjusting its background level to clearly resolve the particle images. Data reduction routines determine the particle image centroids and create time history files. PDT then identifies the velocity vectors which describe the particle movement in the flow field. Graphical data analysis routines are included which allow the user to graph the time history files and display the velocity vector maps, interpolated velocity vector grids, iso-velocity vector contours, and flow streamlines. The PDT data processing software is written in FORTRAN 77 and the data acquisition routine is written in C-Language for 80386-based IBM PC compatibles running MS-DOS v3.0 or higher. Machine requirements include 4 MB RAM (3 MB Extended), a single or

  20. Equilibrium molecular theory of two-dimensional adsorbate drops on surfaces of heterogeneous adsorbents

    NASA Astrophysics Data System (ADS)

    Tovbin, Yu. K.

    2016-08-01

    A molecular statistical theory for calculating the linear tension of small multicomponent droplets in two-dimensional adsorption systems is developed. The theory describes discrete distributions of molecules in space (on a scale comparable to molecular size) and continuous distributions of molecules (at short distances inside cells) in their translational and vibrational motions. Pair intermolecular interaction potentials (the Mie type potential) in several coordination spheres are considered. For simplicity, it is assumed that distinctions in the sizes of mixture components are slight and comparable to the sizes of adsorbent adsorption centers. Expressions for the pressure tensor components inside small droplets on the heterogeneous surface of an adsorbent are obtained, allowing calculations of the thermodynamic characteristics of a vapor-fluid interface, including linear tension. Problems in refining the molecular theory are discussed: describing the properties of small droplets using a coordination model of their structure, considering the effect an adsorbate has on the state of a near-surface adsorbent region, and the surface heterogeneity factor in the conditions for the formation of droplets.

  1. Making methane visible

    NASA Astrophysics Data System (ADS)

    Gålfalk, Magnus; Olofsson, Göran; Crill, Patrick; Bastviken, David

    2016-04-01

    Methane (CH4) is one of the most important greenhouse gases, and an important energy carrier in biogas and natural gas. Its large-scale emission patterns have been unpredictable and the source and sink distributions are poorly constrained. Remote assessment of CH4 with high sensitivity at a m2 spatial resolution would allow detailed mapping of the near-ground distribution and anthropogenic sources in landscapes but has hitherto not been possible. Here we show that CH4 gradients can be imaged on the

  2. Methane monooxygenase: functionalizing methane at iron and copper.

    PubMed

    Sazinsky, Matthew H; Lippard, Stephen J

    2015-01-01

    Methane monooxygenases (MMOs) catalyze the conversion of methane to methanol as the first committed step in the assimilation of this hydrocarbon into biomass and energy by methanotrophs, thus playing a significant role in the biogeochemistry of this potent greenhouse gas. Two distinct enzymes, a copper-dependent membrane protein, particulate methane monooxygenase (pMMO), and an iron-dependent cytosolic protein, soluble methane monooxygenase (sMMO), carry out this transformation using large protein scaffolds that help to facilitate the timely transport of hydrocarbon, O₂, proton, and electron substrates to buried dimetallic active sites. For both enzymes, reaction of the reduced metal centers with O₂leads to intermediates that activate the relatively inert C-H bonds of hydrocarbons to yield oxidized products. Among synthetic and biological catalysts, MMOs are unique because they are the only ones known to hydroxylate methane at ambient temperatures. As a need for new industrial catalysts and green chemical transformations increases, understanding how the different MMO metal centers efficiently accomplish this challenging chemistry has become the focus of intense study. This chapter examines current understanding of the sMMO and pMMO protein structures, their methods for substrate channeling, and mechanisms for the dimetallic activation of O₂and C-H bonds. PMID:25707469

  3. Extended BEG model of monhalogenated methanes physisorbed on ionic crystals

    NASA Astrophysics Data System (ADS)

    Burns, T. E.; Dennison, J. R.; Kite, Jason

    2004-04-01

    The 2D dielectric phases and phase transitions of adsorbed dipolar molecules are modeled using a dilute spin-one Ising model. This model is studied in the Blume-Emery-Griffiths formalism, using a mean-field approximation, where the interaction parameters are uniquely determined from the system interaction energies using an averaging procedure. The model is applied to four monhalogenated methane species physisorbed on MgO(1 0 0) and NaCl(1 0 0) surfaces using previous experimental and theoretical studies to estimate the interaction energy parameters. We find that temperature- and coverage-dependent antiferroelectric to ferroelectric, coverage-dependent ferroelectric up to ferroelectric down, reentrant ferroelectric to ferrielectric, and order-disorder dipole phase transitions can occur. Phase diagrams based on this model are presented.

  4. Methane production from steam-exploded bamboo.

    PubMed

    Kobayashi, Fumihisa; Take, Harumi; Asada, Chikako; Nakamura, Yoshitoshi

    2004-01-01

    To convert unutilized plant biomass into a useful energy source, methane production from bamboo was investigated using a steam explosion pretreatment. Methane could not be produced from raw bamboo but methane production was enhanced by steam explosion. The maximum amount of methane produced, i.e., about 215 ml, was obtained from 1 g of exploded bamboo at a steam pressure of 3.53 MPa and a steaming time of 5 min. A negative correlation between the amount of methane produced and the amount of Klason lignin was observed in the methane fermentation of steam-exploded bamboo.

  5. A flexible sensor measuring displacement and bending

    NASA Astrophysics Data System (ADS)

    Nishijima, Takashi; Yamamoto, Akio; Higuchi, Toshiro

    2009-04-01

    This paper proposes a new sensor that is capable of measuring both linear displacement and bending. The sensor is designed to be used with an electrostatic film motor that features mechanical flexibility, but can also be used as an independent sensor. The sensor employs three-phase electrodes both in sliding and stationary parts and estimates displacement and bending from the change of the capacitance between the electrodes. The paper describes an equivalent capacitance-network model for the sensor. Based on the model, sensing principles for both displacement and bending are presented and analyzed. The analyses are experimentally verified using a prototype sensor. The experimental results show that the prototype sensor could measure both displacement and bending with little interference between them.

  6. Giant adrenal cyst displacing the right kidney.

    PubMed

    Chodisetti, Subbarao; Boddepalli, Yogesh; Kota, Malakondareddy

    2016-01-01

    Adrenal cysts are rare and should be considered in the differential diagnosis of retroperitoneal cysts. We present a case of a huge adrenal cyst displacing the right kidney anteriorly toward the left side in a young female.

  7. Extraction of uranium from seawater using magnetic adsorbents

    SciTech Connect

    Yamashita, H.; Fujita, K.; Nakajima, F.; Ozawa, Y.; Murata, T.

    1981-01-01

    A new process for the extraction of uranium from seawater was developed. In the process, uranium adsorption is effected using powdered magnetic adsorbents; the adsorbents are then separated from seawater using magnetic separation technology. This process is superior to a column method using a granulated hydrous titanium oxide adsorber bed in the following ways: (1) a higher rate of adsorption is realized because smaller particles are used in the uranium adsorption; and (2) blocking, which is inevitable in an adsorber bed, is eliminated. The composite hydrous titanium-iron oxide as a magnetic adsorbent having high uranium adsorption capacity and magnetization can be prepared by adding urea to a mixed solution of titanium sulfate and ferrous sulfate. Adsorption and desoprtion of uranium and the removal of the adsorbent using a small-scale uranium extraction plant (about 15 m/sup 3//d) is reported, and the feasibility of uranium extraction from seawater by this process is demonstrated. 10 figures.

  8. Methane Emission from Tropical Rivers

    NASA Astrophysics Data System (ADS)

    Sawakuchi, H. O.; Rasera, M. F. F. L.; Krusche, A. V.; Ballester, M. V. R.

    2012-04-01

    Inland water is already known as an important source of methane to atmosphere. Methane is produced in anaerobic environments usually find in lakes and floodplain bottom sediment. It is the main reason that almost all information regarding methane flux come from this environments. However, while floodplain dries during low water season reducing methanogenesis, rivers keep the capacity to emit methane throughout the year. Here we present preliminary results of CH4 flux measurements done in 6 large tropical rivers within the Amazon basin. We measured 17 areas using floating chamber during dry (low water) season, between September and November of 2011, in Amazon river mainstem, Araguaia, Xingu, Tapajós, Madeira, and Negro Rivers. Measured fluxes of all rivers ranged from 59.3 to 2974.4 mmol m-2 yr-1. Geomorphologic structure of channels is one important factor that contributes to this high heterogeneity due to development of low flow velocity depositional settings allowing formation of anoxic zones in rivers. Hydraulic and sediment barriers in the confluence of river channels promote the generation of natural dams which function as a trap for the suspension load favoring the deposition of organic rich muds. This kind of environment is very different from common river channels and has a stronger potential of methane emission. Average values of our flux measurements for this two river environments show that depositional areas can have much higher fluxes than the main channel, 1089.6 and 163.1 mmol m-2 yr-1, respectively. Hence, CH4 flux from these depositional zones is similar to some tropical floodplain lakes and reservoirs. Although the low flux from channel, the area covered by water is very large resulting in a significant contribution to the regional methane emission to the atmosphere. Moreover, mapping the area of these depositional river zones will give us a better idea of the magnitude of methane flux from tropical rivers.

  9. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    SciTech Connect

    Tsouris, Costas; Mayes, Richard T.; Janke, Christopher James; Dai, Sheng; Das, S.; Liao, W. -P.; Kuo, Li-Jung; Wood, Jordana; Gill, Gary; Byers, Maggie Flicker; Schneider, Eric

    2015-09-30

    The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) is focused on identifying and implementing actions to assure that nuclear fuel resources are available in the United States. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. This unconventional resource can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uranium recovery from seawater. The goal is to develop advanced adsorbents to reduce the seawater uranium recovery technology cost and uncertainties. Under this program, Oak Ridge National Laboratory (ORNL) has developed a new amidoxime-based adsorbent of high surface area, which tripled the uranium capacity of leading Japanese adsorbents. Parallel efforts have been focused on the optimization of the physicochemical and operating parameters used during the preparation of the adsorbent for deployment. A set of parameters that need to be optimized are related to the conditioning of the adsorbent with alkali solution, which is necessary prior to adsorbent deployment. Previous work indicated that alkali-conditioning parameters significantly affect the adsorbent performance. Initiated in 2014, this study had as a goal to determine optimal parameters such as base type and concentration, temperature, and duration of conditioning that maximize the uranium adsorption performance of amidoxime functionalized adsorbent, while keeping the cost of uranium production low. After base-treatment at various conditions, samples of adsorbent developed at ORNL were tested in this study with batch simulated seawater solution of 8-ppm uranium concentration, batch seawater spiked with uranium nitrate at 75-100 ppb uranium, and continuous

  10. A Modified LBM Model for Simulating Gas Seepage in Fissured Coal Considering Klinkenberg Effects and Adsorbability-Desorbability

    NASA Astrophysics Data System (ADS)

    Tan, Yun-Liang; Teng, Gui-Rong; Zhang, Ze

    2010-01-01

    A modified Lattice-Boltzmann method is proposed by considering the Klinkenberg effect and adsorbability-desorbability for the purpose of simulating methane gas seepage in fissured coal. The results show that the Klinkenberg effect has a little influence on methane gas seepage in fissured coal, so it can be neglected in engineering computations for simplicity. If both the Klinkenberg effect and the adsorbability-desorbability are considered, the Klinkenberg influence on gas pressure decreases as the Darcy coefficient increases. It is found by gas drainage simulations that near a drainage hole, the effect of adsorption and desorption cannot be neglected, and the location of the drainage hole has a great influence on drainage efficient λ when the hole is just located at the mid-zone of the coal seam, λ is 0.691808; when the hole is excursion down to 1.0 m from the mid-zone of coal seam, λ decreases to 0.668631; when the hole is excursion up or down to 2.0 m from the mid-zone of coal seam, λ decreases to 0.632917. The simulations supply an effective approach for optimizing the gas drainage hole location.

  11. Characterization of Methane Degradation and Methane-Degrading Microbes in Alaska Coastal Water

    SciTech Connect

    Kirchman, David L.

    2012-03-29

    The net flux of methane from methane hydrates and other sources to the atmosphere depends on methane degradation as well as methane production and release from geological sources. The goal of this project was to examine methane-degrading archaea and organic carbon oxidizing bacteria in methane-rich and methane-poor sediments of the Beaufort Sea, Alaska. The Beaufort Sea system was sampled as part of a multi-disciplinary expedition (Methane in the Arctic Shelf or MIDAS) in September 2009. Microbial communities were examined by quantitative PCR analyses of 16S rRNA genes and key methane degradation genes (pmoA and mcrA involved in aerobic and anaerobic methane degradation, respectively), tag pyrosequencing of 16S rRNA genes to determine the taxonomic make up of microbes in these sediments, and sequencing of all microbial genes (metagenomes ). The taxonomic and functional make-up of the microbial communities varied with methane concentrations, with some data suggesting higher abundances of potential methane-oxidizing archaea in methane-rich sediments. Sequence analysis of PCR amplicons revealed that most of the mcrA genes were from the ANME-2 group of methane oxidizers. According to metagenomic data, genes involved in methane degradation and other degradation pathways changed with sediment depth along with sulfate and methane concentrations. Most importantly, sulfate reduction genes decreased with depth while the anaerobic methane degradation gene (mcrA) increased along with methane concentrations. The number of potential methane degradation genes (mcrA) was low and inconsistent with other data indicating the large impact of methane on these sediments. The data can be reconciled if a small number of potential methane-oxidizing archaea mediates a large flux of carbon in these sediments. Our study is the first to report metagenomic data from sediments dominated by ANME-2 archaea and is one of the few to examine the entire microbial assemblage potentially involved in

  12. Multiplexed detection of DNA sequences using a competitive displacement assay in a microfluidic SERRS-based device.

    PubMed

    Yazdi, Soroush H; Giles, Kristen L; White, Ian M

    2013-11-01

    We demonstrate sensitive and multiplexed detection of DNA sequences through a surface enhanced resonance Raman spectroscopy (SERRS)-based competitive displacement assay in an integrated microsystem. The use of the competitive displacement scheme, in which the target DNA sequence displaces a Raman-labeled reporter sequence that has lower affinity for the immobilized probe, enables detection of unlabeled target DNA sequences with a simple single-step procedure. In our implementation, the displacement reaction occurs in a microporous packed column of silica beads prefunctionalized with probe-reporter pairs. The use of a functionalized packed-bead column in a microfluidic channel provides two major advantages: (i) immobilization surface chemistry can be performed as a batch process instead of on a chip-by-chip basis, and (ii) the microporous network eliminates the diffusion limitations of a typical biological assay, which increases the sensitivity. Packed silica beads are also leveraged to improve the SERRS detection of the Raman-labeled reporter. Following displacement, the reporter adsorbs onto aggregated silver nanoparticles in a microfluidic mixer; the nanoparticle-reporter conjugates are then trapped and concentrated in the silica bead matrix, which leads to a significant increase in plasmonic nanoparticles and adsorbed Raman reporters within the detection volume as compared to an open microfluidic channel. The experimental results reported here demonstrate detection down to 100 pM of the target DNA sequence, and the experiments are shown to be specific, repeatable, and quantitative. Furthermore, we illustrate the advantage of using SERRS by demonstrating multiplexed detection. The sensitivity of the assay, combined with the advantages of multiplexed detection and single-step operation with unlabeled target sequences makes this method attractive for practical applications. Importantly, while we illustrate DNA sequence detection, the SERRS-based competitive

  13. Isomerization reactions on single adsorbed molecules.

    PubMed

    Morgenstern, Karina

    2009-02-17

    Molecular switches occur throughout nature. In one prominent example, light induces the isomerization of retinal from the compact 11-cis form to the elongated all-trans form, a conversion that triggers the transformation of light into a neural impulse in the eye. Applying these natural principles to synthetic systems offers a promising way to construct smaller and faster nanoelectronic devices. In such systems, electronic switches are essential components for storage and logical operations. The development of molecular switches on the single-molecule level would represent a major step toward incorporating molecules as building units into nanoelectronic circuits. Molecular switches must be both reversible and bistable. To meet these requirements, a molecule must have at least two different thermally stable forms and a way to repeatedly interconvert between those forms based on changes in light, heat, pressure, magnetic or electric fields, pH, mechanical forces, or electric currents. The conversion should be connected to a measurable change in electronic, optical, magnetic, or mechanical properties. Because isomers can differ significantly in physical and chemical properties, isomerization could serve as a molecular switching mechanism. Integration of molecular switches into larger circuits will probably require arranging them on surfaces, which will require a better understanding of isomerization reactions in these environments. In this Account, we describe our scanning tunneling microscopy studies of the isomerization of individual molecules adsorbed on metal surfaces. Investigating chlorobenzene and azobenzene derivatives on the fcc(111) faces of Ag, Cu, and Au, we explored the influence of substituents and the substrate on the excitation mechanism of the isomerization reaction induced by inelastically tunneling electrons. We achieved an irreversible configurational (cis-trans) isomerization of individual 4-dimethyl-amino-azobenzene-4-sulfonic acid molecules on Au

  14. Anaerobic Methane Oxidation: Occurrence and Ecology

    PubMed Central

    Zehnder, Alexander J. B.; Brock, Thomas D.

    1980-01-01

    Anoxic sediments and digested sewage sludge anaerobically oxidized methane to carbon dioxide while producing methane. This strictly anaerobic process showed a temperature optimum between 25 and 37°C, indicating an active microbial participation in this reaction. Methane oxidation in these anaerobic habitats was inhibited by oxygen. The rate of the oxidation followed the rate of methane production. The observed anoxic methane oxidation in Lake Mendota and digested sewage sludge was more sensitive to 2-bromoethanesulfonic acid than the simultaneous methane formation. Sulfate diminished methane formation as well as methane oxidation. However, in the presence of iron and sulfate the ratio of methane oxidized to methane formed increased markedly. Manganese dioxide and higher partial pressures of methane also stimulated the oxidation. The rate of methane oxidation in untreated samples was approximately 2% of the CH4 production rate in Lake Mendota sediments and 8% of that in digested sludge. This percentage could be increased up to 90% in sludge in the presence of 10 mM ferrous sulfate and at a partial pressure of methane of 20 atm (2,027 kPa). PMID:16345488

  15. Effect of adsorbed metals ions on the transport of Zn- and Ni-EDTA complexes in a sand and gravel aquifer

    USGS Publications Warehouse

    Kent, D.B.; Davis, J.A.; Anderson, L.C.D.; Rea, B.A.; Coston, J.A.

    2002-01-01

    Adsorption, complexation, and dissolution reactions strongly influenced the transport of metal ions complexed with ethylenediaminetetraacetic acid (EDTA) in a predominantly quartz-sand aquifer during two tracer tests conducted under mildly reducing conditions at pH 5.8 to 6.1. In tracer test M89, EDTA complexes of zinc (Zn) and nickel (Ni), along with excess free EDTA, were injected such that the lower portion of the tracer cloud traveled through a region with adsorbed manganese (Mn) and the upper portion of the tracer cloud traveled through a region with adsorbed Zn. In tracer test S89, Ni- and Zn-EDTA complexes, along with excess EDTA complexed with calcium (Ca), were injected into a region with adsorbed Mn. The only discernable chemical reaction between Ni-EDTA and the sediments was a small degree of reversible adsorption leading to minor retardation. In the absence of adsorbed Zn, the injected Zn was displaced from EDTA complexes by iron(III) [Fe(III)] dissolved from the sediments. Displacement of Zn by Fe(III) on EDTA became increasingly thermodynamically favorable with decreasing total EDTA concentration. The reaction was slow compared to the time-scale of transport. Free EDTA rapidly dissolved aluminum (Al) from the sediments, which was subsequently displaced slowly by Fe. In the portion of tracer cloud M89 that traveled through the region contaminated with adsorbed Zn, little displacement of Zn complexed with EDTA was observed, and Al was rapidly displaced from EDTA by Zn desorbed from the sediments, in agreement with equilibrium calculations. In tracer test S89, desorption of Mn dominated over the more thermodynamically favorable dissolution of Al oxyhydroxides. Comparison with results from M89 suggests that dissolution of Al oxyhydroxides in coatings on these sediment grains by Ca-EDTA was rate-limited whereas that by free EDTA reached equilibrium on the time-scale of transport. Rates of desorption are much faster than rates of dissolution of Fe

  16. Air stripper VOC treatment using specialized adsorbents

    SciTech Connect

    Craven, C.N.; Blystone, P.G.; Grant, A.

    1994-12-31

    Abatement of volatile organic compound (VOC) emissions is required by federal, state and local regulatory agencies. Sources of VOC emissions include air stripping processes at groundwater remediation and industrial wastewater operations. The Purus A2000 system is an innovative emission control system that utilizes specialized adsorbent resins, on-site regeneration and solvent recovery for abatement of VOCs. This paper describes two applications in which air stripper off-gas is treated by the Purus A2000 Adsorption System. The first is a groundwater remediation pump-and-treat operation in which the air stripper off-gas contains chlorinated solvents. At the second site, benzene and styrene emissions from an industrial wastewater air stripper operation were successfully treated. At both sites the recovered solvent was recycled. Capital and operating costs will be compared to other treatment methods.

  17. Trends in adsorbate induced core level shifts

    NASA Astrophysics Data System (ADS)

    Nilsson, Viktor; Van den Bossche, Maxime; Hellman, Anders; Grönbeck, Henrik

    2015-10-01

    Photoelectron core level spectroscopy is commonly used to monitor atomic and molecular adsorption on metal surfaces. As changes in the electron binding energies are convoluted measures with different origins, calculations are often used to facilitate the decoding of experimental signatures. The interpretation could in this sense benefit from knowledge on trends in surface core level shifts for different metals and adsorbates. Here, density functional theory calculations have been used to systematically evaluate core level shifts for (111) and (100) surfaces of 3d, 4d, and 5d transition metals upon CO, H, O and S adsorption. The results reveal trends and several non-intuitive cases. Moreover, the difficulties correlating core level shifts with charging and d-band shifts are underlined.

  18. Linear transport models for adsorbing solutes

    NASA Astrophysics Data System (ADS)

    Roth, K.; Jury, W. A.

    1993-04-01

    A unified linear theory for the transport of adsorbing solutes through soils is presented and applied to analyze movement of napropamide through undisturbed soil columns. The transport characteristics of the soil are expressed in terms of the travel time distribution of the mobile phase which is then used to incorporate local interaction processes. This approach permits the analysis of all linear transport processes, not only the small subset for which a differential description is known. From a practical point of view, it allows the direct use of measured concentrations or fluxes of conservative solutes to characterize the mobile phase without first subjecting them to any model. For complicated flow regimes, this may vastly improve the identification of models and estimation of their parameters for the local adsorption processes.

  19. The persistence length of adsorbed dendronized polymers

    NASA Astrophysics Data System (ADS)

    Grebikova, Lucie; Kozhuharov, Svilen; Maroni, Plinio; Mikhaylov, Andrey; Dietler, Giovanni; Schlüter, A. Dieter; Ullner, Magnus; Borkovec, Michal

    2016-07-01

    The persistence length of cationic dendronized polymers adsorbed onto oppositely charged substrates was studied by atomic force microscopy (AFM) and quantitative image analysis. One can find that a decrease in the ionic strength leads to an increase of the persistence length, but the nature of the substrate and of the generation of the side dendrons influence the persistence length substantially. The strongest effects as the ionic strength is being changed are observed for the fourth generation polymer adsorbed on mica, which is a hydrophilic and highly charged substrate. However, the observed dependence on the ionic strength is much weaker than the one predicted by the Odijk, Skolnik, and Fixman (OSF) theory for semi-flexible chains. Low-generation polymers show a variation with the ionic strength that resembles the one observed for simple and flexible polyelectrolytes in solution. For high-generation polymers, this dependence is weaker. Similar dependencies are found for silica and gold substrates. The observed behavior is probably caused by different extents of screening of the charged groups, which is modified by the polymer generation, and to a lesser extent, the nature of the substrate. For highly ordered pyrolytic graphite (HOPG), which is a hydrophobic and weakly charged substrate, the electrostatic contribution to the persistence length is much smaller. In the latter case, we suspect that specific interactions between the polymer and the substrate also play an important role.The persistence length of cationic dendronized polymers adsorbed onto oppositely charged substrates was studied by atomic force microscopy (AFM) and quantitative image analysis. One can find that a decrease in the ionic strength leads to an increase of the persistence length, but the nature of the substrate and of the generation of the side dendrons influence the persistence length substantially. The strongest effects as the ionic strength is being changed are observed for the fourth

  20. 46 CFR 154.703 - Methane (LNG).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.703 Methane (LNG). Unless a cargo tank carrying methane (LNG)...

  1. Biogeochemistry: Rebalancing the global methane budget

    NASA Astrophysics Data System (ADS)

    Allen, Grant

    2016-10-01

    A database of the carbon-isotope 'fingerprints' of methane has been used to constrain the contributions of different sources to the global methane budget. The surprising results have implications for climate prediction. See Letter p.88

  2. Hello, Water -- Good-bye, Methane

    NASA Video Gallery

    An animation shows carbon, hydrogen and oxygen atoms. Two hydrogen atoms join each oxygen atom to make water, or H2O. Four hydrogen atoms join a carbon atom to make methane, or CH4. The methane the...

  3. Method for the photocatalytic conversion of methane

    DOEpatents

    Noceti, Richard P.; Taylor, Charles E.; D'Este, Joseph R.

    1998-01-01

    A method for converting methane to methanol is provided comprising subjecting the methane to visible light in the presence of a catalyst and an electron transfer agent. Another embodiment of the invention provides for a method for reacting methane and water to produce methanol and hydrogen comprising preparing a fluid containing methane, an electron transfer agent and a photolysis catalyst, and subjecting said fluid to visible light for an effective period of time.

  4. Method for the photocatalytic conversion of methane

    DOEpatents

    Noceti, R.P.; Taylor, C.E.; D`Este, J.R.

    1998-02-24

    A method for converting methane to methanol is provided comprising subjecting the methane to visible light in the presence of a catalyst and an electron transfer agent. Another embodiment of the invention provides for a method for reacting methane and water to produce methanol and hydrogen comprising preparing a fluid containing methane, an electron transfer agent and a photolysis catalyst, and subjecting said fluid to visible light for an effective period of time. 3 figs.

  5. Potential methane reservoirs beneath Antarctica.

    PubMed

    Wadham, J L; Arndt, S; Tulaczyk, S; Stibal, M; Tranter, M; Telling, J; Lis, G P; Lawson, E; Ridgwell, A; Dubnick, A; Sharp, M J; Anesio, A M; Butler, C E H

    2012-08-30

    Once thought to be devoid of life, the ice-covered parts of Antarctica are now known to be a reservoir of metabolically active microbial cells and organic carbon. The potential for methanogenic archaea to support the degradation of organic carbon to methane beneath the ice, however, has not yet been evaluated. Large sedimentary basins containing marine sequences up to 14 kilometres thick and an estimated 21,000 petagrams (1 Pg equals 10(15) g) of organic carbon are buried beneath the Antarctic Ice Sheet. No data exist for rates of methanogenesis in sub-Antarctic marine sediments. Here we present experimental data from other subglacial environments that demonstrate the potential for overridden organic matter beneath glacial systems to produce methane. We also numerically simulate the accumulation of methane in Antarctic sedimentary basins using an established one-dimensional hydrate model and show that pressure/temperature conditions favour methane hydrate formation down to sediment depths of about 300 metres in West Antarctica and 700 metres in East Antarctica. Our results demonstrate the potential for methane hydrate accumulation in Antarctic sedimentary basins, where the total inventory depends on rates of organic carbon degradation and conditions at the ice-sheet bed. We calculate that the sub-Antarctic hydrate inventory could be of the same order of magnitude as that of recent estimates made for Arctic permafrost. Our findings suggest that the Antarctic Ice Sheet may be a neglected but important component of the global methane budget, with the potential to act as a positive feedback on climate warming during ice-sheet wastage.

  6. Potential methane reservoirs beneath Antarctica.

    PubMed

    Wadham, J L; Arndt, S; Tulaczyk, S; Stibal, M; Tranter, M; Telling, J; Lis, G P; Lawson, E; Ridgwell, A; Dubnick, A; Sharp, M J; Anesio, A M; Butler, C E H

    2012-08-30

    Once thought to be devoid of life, the ice-covered parts of Antarctica are now known to be a reservoir of metabolically active microbial cells and organic carbon. The potential for methanogenic archaea to support the degradation of organic carbon to methane beneath the ice, however, has not yet been evaluated. Large sedimentary basins containing marine sequences up to 14 kilometres thick and an estimated 21,000 petagrams (1 Pg equals 10(15) g) of organic carbon are buried beneath the Antarctic Ice Sheet. No data exist for rates of methanogenesis in sub-Antarctic marine sediments. Here we present experimental data from other subglacial environments that demonstrate the potential for overridden organic matter beneath glacial systems to produce methane. We also numerically simulate the accumulation of methane in Antarctic sedimentary basins using an established one-dimensional hydrate model and show that pressure/temperature conditions favour methane hydrate formation down to sediment depths of about 300 metres in West Antarctica and 700 metres in East Antarctica. Our results demonstrate the potential for methane hydrate accumulation in Antarctic sedimentary basins, where the total inventory depends on rates of organic carbon degradation and conditions at the ice-sheet bed. We calculate that the sub-Antarctic hydrate inventory could be of the same order of magnitude as that of recent estimates made for Arctic permafrost. Our findings suggest that the Antarctic Ice Sheet may be a neglected but important component of the global methane budget, with the potential to act as a positive feedback on climate warming during ice-sheet wastage. PMID:22932387

  7. Optical constants of solid methane

    NASA Technical Reports Server (NTRS)

    Khare, Bishun N.; Thompson, W. R.; Sagan, C.; Arakawa, E. T.; Bruel, C.; Judish, J. P.; Khanna, R. K.; Pollack, J. B.

    1990-01-01

    Methane is the most abundant simple organic molecule in the outer solar system bodies. In addition to being a gaseous constituent of the atmospheres of the Jovian planets and Titan, it is present in the solid form as a constituent of icy surfaces such as those of Triton and Pluto, and as cloud condensate in the atmospheres of Titan, Uranus, and Neptune. It is expected in the liquid form as a constituent of the ocean of Titan. Cometary ices also contain solid methane. The optical constants for both solid and liquid phases of CH4 for a wide temperature range are needed for radiative transfer calculations, for studies of reflection from surfaces, and for modeling of emission in the far infrared and microwave regions. The astronomically important visual to near infrared measurements of solid methane optical constants are conspicuously absent from the literature. Preliminary results are presented on the optical constants of solid methane for the 0.4 to 2.6 micrometer region. Deposition onto a substrate at 10 K produces glassy (semi-amorphous) material. Annealing this material at approximately 33 K for approximately 1 hour results in a crystalline material as seen by sharper, more structured bands and negligible background extinction due to scattering. The constant k is reported for both the amorphous and the crystalline (annealed) states. Typical values (at absorption maxima) are in the .001 to .0001 range. Below lambda = 1.1 micrometers the bands are too weak to be detected by transmission through the films less than or equal to 215 micrometers in thickness, employed in the studies to date. Using previously measured values of the real part of the refractive index, n, of liquid methane at 110 K, n is computed for solid methane using the Lorentz-Lorenz relationship. Work is in progress to extend the measurements of optical constants n and k for liquid and solid to both shorter and longer wavelengths, eventually providing a complete optical constants database for

  8. Mechanical properties of hexadecane-water interfaces with adsorbed hydrophobic bacteria

    NASA Astrophysics Data System (ADS)

    Kang, Zhewen

    sheets, and (b) with a reduction in cell concentration in the aqueous phase, less oil was emulsified, but the elastic moduli of the adsorbed films remained unchanged. These results are in contrast to the above millimetre-scale study. Therefore the rheological properties of these bacteria-adsorbed films appear to be length scale-dependent. An oil displacement experiment was designed to investigate the flow behaviour of micron-scale emulsion drops in a constricted channel. The qualitative results can be correlated with the interfacial rheological properties and may have valuable relevance to the study of multiphase flow through constricted channels in porous rocks (e.g. in MEOR operations).

  9. Is there methane on Mars?

    NASA Astrophysics Data System (ADS)

    Zahnle, Kevin; Freedman, Richard S.; Catling, David C.

    2011-04-01

    There have been several reports of methane on Mars at the 10-60 ppbv level. Most suggest that methane is both seasonally and latitudinally variable. Here we review why variable methane on Mars is physically and chemically implausible, and then we critically review the published reports. There is no known mechanism for destroying methane chemically on Mars. But if there is one, methane oxidation would deplete the O 2 in Mars's atmosphere in less than 10,000 years unless balanced by an equally large unknown source of oxidizing power. Physical sequestration does not raise these questions, but adsorption in the regolith or condensation in clathrates ignore competition for adsorption sites or are inconsistent with clathrate stability, respectively. Furthermore, any mechanism that relies on methane's van der Waals' attraction is inconsistent with the continued presence of Xe in the atmosphere at the 60 ppbv level. We then use the HITRAN database and transmission calculations to identify and characterize the absorption lines that would be present on Earth or Mars at the wavelengths of the published observations. These reveal strong competing telluric absorption that is most problematic at just those wavelengths where methane's signature seems most clearly seen from Earth. The competing telluric lines must be removed with models. The best case for martian methane was made for the 12CH 4ν3 R0 and R1 lines seen in blueshift when Mars was approaching Earth in early 2003 (Mumma, M.J., Villanueva, G.L., Novak, R.E., Hewagama, T., Bonev, B.P., DiSanti, M.A., Mandell, A.M., Smith, M.D. [2009]. Science 323, 1041-1045). For these the Doppler shift moves the two martian lines into near coincidence with telluric 13CH 4ν3 R1 and R2 lines that are 10-50× stronger than the inferred martian lines. By contrast, the 12CH 4ν3 R0 and R1 lines when observed in redshift do not contend with telluric 13CH 4. For these lines, Mumma et al.'s observations and analyses are consistent with an

  10. Coalbed methane production case histories

    SciTech Connect

    Not Available

    1981-02-01

    The production of methane gas from coal and coal-bearing rocks is one of the prime objectives of the Department of Energy's Methane Recovery from Coalbeds Project. This report contains brief description of wells that are presently producing gas from coal or coal-bearing rocks. Data from three gob gas production areas in Illinois, an in-mine horizontal borehole degasification, and eleven vertical boreholes are presented. Production charts and electric logs of the producing zones are included for some of the wells. Additional information on dry gas production from the San Juan Basin, Colorado/New Mexico and the Greater Green River Coal Region, Colorado/Wyoming is also included.

  11. Terminating marine methane bubbles by superhydrophobic sponges.

    PubMed

    Chen, Xiao; Wu, Yuchen; Su, Bin; Wang, Jingming; Song, Yanlin; Jiang, Lei

    2012-11-14

    Marine methane bubbles are absorbed, steadily stored, and continuously transported based on the employment of superhydrophobic sponges. Antiwetting sponges are water-repellent in the atmosphere and absorb gas bubbles under water. Their capacity to store methane bubbles increases with enhanced submerged depth. Significantly, trapped methane bubbles can be continuously transported driven by differential pressure.

  12. APPROACH FOR ESTIMATING GLOBAL LANDFILL METHANE EMISSIONS

    EPA Science Inventory

    The report is an overview of available country-specific data and modeling approaches for estimating global landfill methane. Current estimates of global landfill methane indicate that landfills account for between 4 and 15% of the global methane budget. The report describes an ap...

  13. Are methane production and cattle performance related?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methane is a product of fermentation of feed in ruminant animals. Approximately 2 -12% of the gross energy consumed by cattle is released through enteric methane production. There are three primary components that contribute to the enteric methane footprint of an animal. Those components are dry ...

  14. 78 FR 37536 - Methane Hydrate Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-21

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Methane... meeting. SUMMARY: This notice announces a meeting of the Methane Hydrate Advisory Committee. The Federal... of the Methane Hydrate Advisory Committee is to provide advice on potential applications of...

  15. 40 CFR 721.4820 - Methane, bromodifluoro-.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Methane, bromodifluoro-. 721.4820... Substances § 721.4820 Methane, bromodifluoro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as methane, bromodifluoro- is subject to reporting...

  16. 30 CFR 75.342 - Methane monitors.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Methane monitors. 75.342 Section 75.342 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.342 Methane monitors. (a)(1) MSHA approved methane monitors shall be installed on all face cutting machines, continuous miners, longwall...

  17. 30 CFR 75.342 - Methane monitors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Methane monitors. 75.342 Section 75.342 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.342 Methane monitors. (a)(1) MSHA approved methane monitors shall be installed on all face cutting machines, continuous miners, longwall...

  18. 40 CFR 721.4820 - Methane, bromodifluoro-.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Methane, bromodifluoro-. 721.4820... Substances § 721.4820 Methane, bromodifluoro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as methane, bromodifluoro- is subject to reporting...

  19. 30 CFR 75.342 - Methane monitors.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Methane monitors. 75.342 Section 75.342 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.342 Methane monitors. (a)(1) MSHA approved methane monitors shall be installed on all face cutting machines, continuous miners, longwall...

  20. 76 FR 59667 - Methane Hydrate Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-27

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Methane... Meeting. SUMMARY: This notice announces a meeting of the Methane Hydrate Advisory Committee. Federal... of the Committee: The purpose of the Methane Hydrate Advisory Committee is to provide advice...

  1. 78 FR 26337 - Methane Hydrate Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-06

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Methane... Meeting. SUMMARY: This notice announces a meeting of the Methane Hydrate Advisory Committee. The Federal... of the Methane Hydrate Advisory Committee is to provide advice on potential applications of...

  2. 30 CFR 75.342 - Methane monitors.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Methane monitors. 75.342 Section 75.342 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.342 Methane monitors. (a)(1) MSHA approved methane monitors shall be installed on all face cutting machines, continuous miners, longwall...

  3. Quantification of the vocal folds’ dynamic displacements

    NASA Astrophysics Data System (ADS)

    del Socorro Hernández-Montes, María; Muñoz, Silvino; De La Torre, Manuel; Flores, Mauricio; Pérez, Carlos; Mendoza-Santoyo, Fernando

    2016-05-01

    Fast dynamic data acquisition techniques are required to investigate the motional behavior of the vocal folds (VFs) when they are subjected to a steady air-flow through the trachea. High-speed digital holographic interferometry (DHI) is a non-invasive full-field-of-view technique that has proved its usefulness to study rapid and non-repetitive object movements. Hence it is an ideal technique used here to measure VF displacements and vibration patterns at 2000 fps. Analyses from a set of 200 displacement images showed that VFs’ vibration cycles are established along their width (y) and length (x). Furthermore, the maximum deformation for the right and left VFs’ area may be quantified from these images, which in itself represents an important result in the characterization of this structure. At a controlled air pressure, VF displacements fall within the range ~100-1740 nm, with a calculated precision and accuracy that yields a variation coefficient of 1.91%. High-speed acquisition of full-field images of VFs and their displacement quantification are on their own significant data in the study of their functional and physiological behavior since voice quality and production depend on how they vibrate, i.e. their displacement amplitude and frequency. Additionally, the use of high speed DHI avoids prolonged examinations and represents a significant scientific and technological alternative contribution in advancing the knowledge and working mechanisms of these tissues.

  4. Conflict induced internal displacement in Nepal.

    PubMed

    Singh, Sonal; Sharma, Sharan Prakash; Mills, Edward; Poudel, Krishna C; Jimba, Masamine

    2007-01-01

    Nepal has witnessed a humanitarian crisis since the Maoist conflict began ten years ago. The plight of internally displaced persons (IDPs) in Nepal has received little international attention despite being rated one of the worst displacement scenarios in the world. An estimated 200,000 people have been displaced as a result of the conflict, with the far-western districts of Nepal being the worst affected. Internal displacement has stretched the carrying capacity of several cities with adverse physical and mental health consequences for the displaced. Vulnerable women and children have been the worst affected. The government has adopted a discriminatory approach and failed to fulfil its obligations towards IDPs. Non-governmental organisations and international agencies have provided inadequate services to IDPs in their programmes. Tackling the issues of IDPs requires co-operation between government and development agencies: acknowledging the burden of the problem of IDPs, adequate registration and needs assessment, along with health and nutritional surveys, and development of short-term emergency relief packages and long-term programmes for their assistance. PMID:17542185

  5. Ultra-Sensitive Magnetoresistive Displacement Sensing Device

    NASA Technical Reports Server (NTRS)

    Olivas, John D. (Inventor); Lairson, Bruce M. (Inventor); Ramesham, Rajeshuni (Inventor)

    2003-01-01

    An ultrasensitive displacement sensing device for use in accelerometers, pressure gauges, temperature transducers, and the like, comprises a sputter deposited, multilayer, magnetoresistive field sensor with a variable electrical resistance based on an imposed magnetic field. The device detects displacement by sensing changes in the local magnetic field about the magnetoresistive field sensor caused by the displacement of a hard magnetic film on a movable microstructure. The microstructure, which may be a cantilever, membrane, bridge, or other microelement, moves under the influence of an acceleration a known displacement predicted by the configuration and materials selected, and the resulting change in the electrical resistance of the MR sensor can be used to calculate the displacement. Using a micromachining approach, very thin silicon and silicon nitride membranes are fabricated in one preferred embodiment by means of anisotropic etching of silicon wafers. Other approaches include reactive ion etching of silicon on insulator (SOI), or Low Pressure Chemical Vapor Deposition of silicon nitride films over silicon substrates. The device is found to be improved with the use of giant magnetoresistive elements to detect changes in the local magnetic field.

  6. Fingering phenomena during grain-grain displacement

    NASA Astrophysics Data System (ADS)

    Mello, Nathália M. P.; Paiva, Humberto A.; Combe, G.; Atman, A. P. F.

    2016-05-01

    Spontaneous formation of fingered patterns during the displacement of dense granular assemblies was experimentally reported few years ago, in a radial Hele-Shaw cell. Here, by means of discrete element simulations, we have recovered the experimental findings and extended the original study to explore the control parameters space. In particular, using assemblies of grains with different geometries (monodisperse, bidisperse, or polydisperse), we measured the macroscopic stress tensor in the samples in order to confirm some conjectures proposed in analogy with Saffman-Taylor viscous fingering phenomena for immiscible fluids. Considering an axial setup which allows to control the discharge of grains and to follow the trajectory and the pressure gradient along the displacing interface, we have applied the Darcy law for laminar flow in fluids in order to measure an "effective viscosity" for each assembly combination, in an attempt to mimic variation of the viscosity ratio between the injected/displaced fluids in the Saffman-Taylor experiment. The results corroborate the analogy with the viscous fluids displacement, with the bidisperse assembly corresponding to the less viscous geometry. But, differently to fluid case, granular fingers only develop for a specific combination of displaced/injected geometries, and we have demonstrated that it is always related with the formation of a force chain network along the finger direction.

  7. Probing interactions between TiO 2 photocatalyst and adsorbing species using quartz crystal microbalance

    NASA Astrophysics Data System (ADS)

    Morand, R.; Noworyta, K.; Augustynski, J.

    2002-10-01

    Photoactivity of nanocrystalline TiO 2 films is shown to be strongly affected by the presence in aqueous solution of salicylic acid, known to form Ti(IV)salicylate surface complexes. In particular, the photooxidation of methanol - an effective hole scavenger - at TiO 2 appears to be in part, or even completely inhibited by the additions of increasing amounts of salicylic acid. The chemisorption of salicylic and also phthalic acid on TiO 2 was followed using quartz crystal microbalance, QCM. The observed resonant frequency changes of the quartz crystal bearing TiO 2 films, accompanying increasing additions of the benzoic acids to the contacting solutions, indicate large displacement of water as a consequence of the adsorbent-imparted hydrophobicity of the interface.

  8. Surfactant-Wrapped Multiwalled Carbon Nanotubes in Aquatic Systems: Surfactant Displacement in the Presence of Humic Acid.

    PubMed

    Chang, Xiaojun; Bouchard, Dermont C

    2016-09-01

    Sodium dodecyl sulfate (SDS) facilitates multiwalled carbon nanotube (MWCNT) debundling and enhances nanotube stability in the aqueous environment by adsorbing on the nanotube surfaces, thereby increasing repulsive electrostatic forces and steric effects. The resulting SDS-wrapped MWCNTs are utilized in industrial applications and have been widely employed in environmental studies. In the present study, MWCNTs adsorbed SDS during ultrasonication to form stable MWCNTs suspensions. Desorption of SDS from MWCNTs surfaces was then investigated as a function of Suwannee River Humic Acid (SRHA) and background electrolyte concentrations. Due to hydrophobic effects and π-π interactions, MWCNTs exhibit higher affinity for SRHA than SDS. In the presence of SRHA, SDS adsorbed on MWCNTs was displaced. Cations (Na(+), Ca(2+)) decreased SDS desorption from MWCNTs due to charge screening effects. Interestingly, the presence of the divalent calcium cation facilitated multilayered SRHA adsorption on MWCNTs through bridging effects, while monovalent sodium reduced SRHA adsorption. Results of the present study suggest that properties of MWCNTs wrapped with commercial surfactants will be altered when these materials are released to surface waters and the surfactant coating will be displaced by natural organic matter (NOM). Changes on their surfaces will significantly affect MWCNTs fate in aquatic environments. PMID:27500910

  9. The effect of elevated methane pressure on methane hydrate dissociation

    USGS Publications Warehouse

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

    2004-01-01

    Methane hydrate, equilibrated at P, T conditions within the hydrate stability field, was rapidly depressurized to 1.0 or 2.0 MPa and maintained at isobaric conditions outside its stability field, while the extent and rate of hydrate dissociation was measured at fixed, externally maintained temperatures between 250 and 288 K. The dissociation rate decreases with increasing pressure at a given temperature. Dissociation rates at 1.0 MPa parallel the complex, reproducible T-dependence previously observed between 250 and 272 K at 0.1 MPa. The lowest rates were observed near 268 K, such that >50% of the sample can persist for more than two weeks at 0.1 MPa to more than a month at 1 and 2 MPa. Varying the pressure stepwise in a single experiment increased or decreased the dissociation rate in proportion to the rates observed in the isobaric experiments, similar to the rate reversibility previously observed with stepwise changes in temperature at 0.1 MPa. At fixed P, T conditions, the rate of methane hydrate dissociation decreases monotonically with time, never achieving a steady rate. The relationship between time (t) and the extent of hydrate dissociation is empirically described by: Evolved gas (%) = A??tB where the pre-exponential term A ranges from 0 to 16% s-B and the exponent B is generally <1. Based on fits of the dissociation results to Equation 1 for the full range of temperatures (204 to 289 K) and pressures (0.1 to 2.0 MPa) investigated, the derived parameters can be used to predict the methane evolution curves for pure, porous methane hydrate to within ??5%. The effects of sample porosity and the presence of quartz sand and seawater on methane hydrate dissociation are also described using Equation 1.

  10. Structure and properties of water film adsorbed on mica surfaces.

    PubMed

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-14

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet. PMID:26374054

  11. Structure and properties of water film adsorbed on mica surfaces.

    PubMed

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-14

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet.

  12. Displacement Cascade Damage Production in Metals

    SciTech Connect

    Stoller, Roger E; Malerba, Lorenzo; Nordlund, Kai

    2015-01-01

    Radiation-induced changes in microstructure and mechanical properties in structural materials are the result of a complex set of physical processes initiated by the collision between an energetic particle (neutron or ion) and an atom in the lattice. This primary damage event is called an atomic displacement cascade. The simplest description of a displacement cascade is to view it as a series of many billiard-ball-like elastic collisions among the atoms in the material. This chapter describes the formation and evolution of this primary radiation damage mechanism to provide an overview of how stable defects are formed by displacement cascades, as well as the nature and morphology of the defects themselves. The impact of the relevant variables such as cascade energy and irradiation temperature is discussed, and defect formation in different materials is compared.

  13. Amorphization of silicon carbide by carbon displacement

    NASA Astrophysics Data System (ADS)

    Devanathan, R.; Gao, F.; Weber, W. J.

    2004-05-01

    We have used molecular dynamics simulations to examine the possibility of amorphizing silicon carbide (SiC) by exclusively displacing C atoms. At a defect generation corresponding to 0.2 displacements per atom, the enthalpy surpasses the level of melt-quenched SiC, the density decreases by about 15%, and the radial distribution function shows a lack of long-range order. Prior to amorphization, the surviving defects are mainly C Frenkel pairs (67%), but Si Frenkel pairs (18%) and antisite defects (15%) are also present. The results indicate that SiC can be amorphized by C sublattice displacements. Chemical short-range disorder, arising mainly from Frenkel pair production, plays a significant role in the amorphization.

  14. Forced displacement and women's security in Colombia.

    PubMed

    Meertens, Donny

    2010-04-01

    In the protracted Colombian conflict, assistance to internally displaced persons has developed in the context of contradictory political processes. The Colombian government's launching of a transitional justice process in the midst of armed conflict has generated a complex situation displaying both conflict and post-conflict characteristics. The progressive Constitutional Court rulings on internal displacement, in particular the gender-sensitive Auto 092, constitute an attempt to bring together humanitarian interventions and transitional justice measures in a rights-based framework. However, the national government is reluctant to adopt them fully and local realities still hamper their integrated implementation. Displaced women, therefore, remain in an especially vulnerable position. This paper argues that gender-sensitive humanitarian interventions must take into account all of these complexities of scale and political process in order to make legal frameworks more effective at the local level. In these contexts, interventions should pay particular attention to strategies that contribute to transforming pre-existing gender regimes. PMID:20132270

  15. Forced displacement and women's security in Colombia.

    PubMed

    Meertens, Donny

    2010-04-01

    In the protracted Colombian conflict, assistance to internally displaced persons has developed in the context of contradictory political processes. The Colombian government's launching of a transitional justice process in the midst of armed conflict has generated a complex situation displaying both conflict and post-conflict characteristics. The progressive Constitutional Court rulings on internal displacement, in particular the gender-sensitive Auto 092, constitute an attempt to bring together humanitarian interventions and transitional justice measures in a rights-based framework. However, the national government is reluctant to adopt them fully and local realities still hamper their integrated implementation. Displaced women, therefore, remain in an especially vulnerable position. This paper argues that gender-sensitive humanitarian interventions must take into account all of these complexities of scale and political process in order to make legal frameworks more effective at the local level. In these contexts, interventions should pay particular attention to strategies that contribute to transforming pre-existing gender regimes.

  16. Competitive Adsorption of Carbon Dioxide/Methane in Coal: First-Principles Quantum Mechanical Investigations

    NASA Astrophysics Data System (ADS)

    Liu, Yingdi; Wang, Sanwu

    Sequestration of CO2 into geological formations has been suggested to mitigate the effect of the increasing of the atmospheric CO2 concentration on global warming. Coalbeds are investigated as one of the attractive storage sites since the cost of CO2 sequestration can be offset by the enhanced coalbed methane (ECBM) recovery. Extensive experimental studies have been performed for the competitive adsorption of CO2/CH4 into coalbeds. However, the atomic-level understanding for the interaction between the adsorbate (CO2/CH4) and the adsorbent (coal) has not been fully explored. We report first-principles density-functional calculations for the competitive adsorption between CO2/CH4 in the coal network. In particular, we report results of atomic structures, bonding characteristics, energetics, as well as electronic structures of the CO2/CH4-coal systems. This research used the supercomputer resources at NERSC, of XSEDE, at TACC, and at the Tandy Supercomputing Center.

  17. Frictional behavior of large displacement experimental faults

    USGS Publications Warehouse

    Beeler, N.M.; Tullis, T.E.; Blanpied, M.L.; Weeks, J.D.

    1996-01-01

    The coefficient of friction and velocity dependence of friction of initially bare surfaces and 1-mm-thick simulated fault gouges (400 mm at 25??C and 25 MPa normal stress. Steady state negative friction velocity dependence and a steady state fault zone microstructure are achieved after ???18 mm displacement, and an approximately constant strength is reached after a few tens of millimeters of sliding on initially bare surfaces. Simulated fault gouges show a large but systematic variation of friction, velocity dependence of friction, dilatancy, and degree of localization with displacement. At short displacement (<10 mm), simulated gouge is strong, velocity strengthening and changes in sliding velocity are accompanied by relatively large changes in dilatancy rate. With continued displacement, simulated gouges become progressively weaker and less velocity strengthening, the velocity dependence of dilatancy rate decreases, and deformation becomes localized into a narrow basal shear which at its most localized is observed to be velocity weakening. With subsequent displacement, the fault restrengthens, returns to velocity strengthening, or to velocity neutral, the velocity dependence of dilatancy rate becomes larger, and deformation becomes distributed. Correlation of friction, velocity dependence of friction and of dilatancy rate, and degree of localization at all displacements in simulated gouge suggest that all quantities are interrelated. The observations do not distinguish the independent variables but suggest that the degree of localization is controlled by the fault strength, not by the friction velocity dependence. The friction velocity dependence and velocity dependence of dilatancy rate can be used as qualitative measures of the degree of localization in simulated gouge, in agreement with previous studies. Theory equating the friction velocity dependence of simulated gouge to the sum of the friction velocity dependence of bare surfaces and the velocity

  18. Formation of Large Ag Clusters with Shells of Methane, Ethylene, and Acetylene in He Droplets.

    PubMed

    Loginov, Evgeny; Gomez, Luis F; Sartakov, Boris G; Vilesov, Andrey F

    2016-09-01

    Helium droplets were used to assemble composite metal-molecular clusters. Produced clusters have several hundreds of silver atoms in the core, immersed in a shell consisting of methane, ethylene, or acetylene molecules. The structure of the clusters was studied via infrared spectra of the C-H stretches of the hydrocarbon molecules. The spectra of the clusters containing methane and acetylene show two distinct features due to molecules on the interface with silver core and those in the volume of the neat molecular part of the clusters. The relative intensities of the peaks are in good agreement with the estimates based on the number of the captured particles. Experiments also suggest that selection rules for infrared transitions for molecules adsorbed on metal surfaces are also valid for silver clusters as small as 300 atoms. PMID:27500443

  19. Surface atomic relaxation and magnetism on hydrogen-adsorbed Fe(110) surfaces from first principles

    NASA Astrophysics Data System (ADS)

    Chohan, Urslaan K.; Jimenez-Melero, Enrique; Koehler, Sven P. K.

    2016-11-01

    We have computed adsorption energies, vibrational frequencies, surface relaxation and buckling for hydrogen adsorbed on a body-centred-cubic Fe(110) surface as a function of the degree of H coverage. This adsorption system is important in a variety of technological processes such as the hydrogen embrittlement in ferritic steels, which motivated this work, and the Haber-Bosch process. We employed spin-polarised density functional theory to optimise geometries of a six-layer Fe slab, followed by frozen mode finite displacement phonon calculations to compute Fe-H vibrational frequencies. We have found that the quasi-threefold (3f) site is the most stable adsorption site, with adsorption energies of ∼3.0 eV/H for all coverages studied. The long-bridge (lb) site, which is close in energy to the 3f site, is actually a transition state leading to the stable 3f site. The calculated harmonic vibrational frequencies collectively span from 730 to 1220 cm-1, for a range of coverages. The increased first-to-second layer spacing in the presence of adsorbed hydrogen, and the pronounced buckling observed in the Fe surface layer, may facilitate the diffusion of hydrogen atoms into the bulk, and therefore impact the early stages of hydrogen embrittlement in steels.

  20. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface.

    PubMed

    Jiang, Zhuoling; Wang, Hao; Sanvito, Stefano; Hou, Shimin

    2015-12-21

    Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green's function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4pz atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices.

  1. Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface

    SciTech Connect

    Jiang, Zhuoling; Wang, Hao; Sanvito, Stefano; Hou, Shimin

    2015-12-21

    Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green’s function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4p{sub z} atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices.

  2. Maxillary tooth displacement in the infratemporal fossa

    PubMed Central

    Roshanghias, Korosh; Peisker, Andre; Zieron, Jörg Olaf

    2016-01-01

    Wisdom tooth operations are sometimes accompanied by complications. This case report shows complications during upper jaw third molar removal. Expectable problems during oral surgery should be planned to be solved in advance. Displacement of the third molar during oral surgeries as a considerable complication is rarely discussed scientifically. A good design of flap, adequate power for extraction, and clear view on the surgical field are crucial. Three-dimensional radiographic diagnostics in terms of cone beam computed tomography is helpful after tooth displacement into the infratemporal fossa. PMID:27605997

  3. Delayed bone cement displacement following balloon kyphoplasty.

    PubMed

    Wang, Hee Sun; Kim, Hyeun Sung; Ju, Chang Il; Kim, Seok Won

    2008-04-01

    We report a rare case of delayed cement displacement after balloon kyphoplasty in patient with Kümmell's desease. A 78-year-old woman with Kümmell's desease at T12 level received percutaneous balloon kyphoplasty. Two months after surgery, the patient complained of progressive severe back pain. Computed tomographic scans revealed a breakdown of the anterior cortex and anterior displacement of bone cement. Although this complication is very rare, it is likely to occur in treatment of Kümmell's desease accompanying anterior cortical defect. PMID:19096648

  4. Maxillary tooth displacement in the infratemporal fossa.

    PubMed

    Roshanghias, Korosh; Peisker, Andre; Zieron, Jörg Olaf

    2016-01-01

    Wisdom tooth operations are sometimes accompanied by complications. This case report shows complications during upper jaw third molar removal. Expectable problems during oral surgery should be planned to be solved in advance. Displacement of the third molar during oral surgeries as a considerable complication is rarely discussed scientifically. A good design of flap, adequate power for extraction, and clear view on the surgical field are crucial. Three-dimensional radiographic diagnostics in terms of cone beam computed tomography is helpful after tooth displacement into the infratemporal fossa. PMID:27605997

  5. Methane sources and emissions in Italy

    SciTech Connect

    Guidotti, G.R.; Castagnola, A.M.

    1994-12-31

    Methane emissions in Italy were assessed in the framework of the measures taken to follow out the commitments undertaken at the 1992 U.N. Conference for Environment and Development. Methane emissions of anthropic origin were estimated to be in the range of 1.6 to 2.3 million ton of methane per year. Some of these methane sources (natural gas production, transmission and distribution; rice paddies; managed livestock enteric fermentation and waste; solid waste landfills) are given here particular care as they mainly contribute to the total methane emission budget.

  6. Methane on Triton - Physical state and distribution

    NASA Technical Reports Server (NTRS)

    Cruikshank, D. P.; Apt, J.

    1984-01-01

    Infrared spectrophotometric measurements of Neptune's satellite Triton obtained between 1980 and 1982 in the spectral range 0.8-2.5 microns show six individual absorption bands attributable to methane. An additional band in the Triton data is not methane. The Triton spectral data conform more closely to a laboratory spectrum of frozen methane than to a synthetic spectrum of methane gas computed for conditions of low temperature expected at the satellite. Additionally, the strength of the bands vary with Triton's orbital position. The data thus suggest that methane in the ice phase is mostly responsible for the bands in Triton's spectrum, and that the ice is distributed nonuniformly around the satellite's surface.

  7. Methane Dynamics in Flooded Lands

    EPA Science Inventory

    Methane (CH4) is the second most important anthropogenic greenhouse gas with a heat trapping capacity 34 times greater than that of carbon dioxide on a100 year time scale. Known anthropogenic CH4 sources include livestock production, rice agriculture, landfills, and natural gas m...

  8. Bis(2-chloroethoxy)methane

    Integrated Risk Information System (IRIS)

    Bis ( 2 - chloroethoxy ) methane ; CASRN 111 - 91 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for

  9. Methane flux from Minnesota peatlands

    SciTech Connect

    Crill, P.M.; Bartlett, K.B.; Harriss, R.C.; Gorham, E.; Verry, E.S. )

    1988-12-01

    Northern (> 40 deg N) wetlands have been suggested as the largest natural source of methane (CH{sub 4}) to the troposphere. To refine the authors estimates of source strengths from this region and to investigate climatic controls on the process, fluxes were measured from a variety of Minnesota peatlands during May, June, and August 1986. Late spring and summer fluxes ranged from 11 to 866 mg CH{sub 4}/sq/m/day, averaging 207 mg CH{sub 4} sq/m/day overall. At Marcell Forest, forested bogs and fen sites had lower fluxes than open bogs. In the Red Lake peatland, circumneutral fens, with standing water above the peat surface, produced more methane than acid bog sites in which the water table was beneath the moss surface. Peat temperature was an important control. Methane flux increased in response to increasing soil temperature. It is estimated that the methane flux from all peatlands north of 40 deg may be on the order of 70 to 90 Tg/yr though estimates of this sort are plagued by uncertainties in the areal extent of peatlands, length of the CH{sub 4} producing season, and the spatial and temporal variability of the flux. 60 refs., 7 figs., 5 tabs.

  10. Methane production by attached film

    DOEpatents

    Jewell, William J.

    1981-01-01

    A method for purifying wastewater of biodegradable organics by converting the organics to methane and carbon dioxide gases is disclosed, characterized by the use of an anaerobic attached film expanded bed reactor for the reaction process. Dilute organic waste material is initially seeded with a heterogeneous anaerobic bacteria population including a methane-producing bacteria. The seeded organic waste material is introduced into the bottom of the expanded bed reactor which includes a particulate support media coated with a polysaccharide film. A low-velocity upward flow of the organic waste material is established through the bed during which the attached bacterial film reacts with the organic material to produce methane and carbon dioxide gases, purified water, and a small amount of residual effluent material. The residual effluent material is filtered by the film as it flows upwardly through the reactor bed. In a preferred embodiment, partially treated effluent material is recycled from the top of the bed to the bottom of the bed for further treatment. The methane and carbon dioxide gases are then separated from the residual effluent material and purified water.

  11. Methane storage in molecular nanostructures

    NASA Astrophysics Data System (ADS)

    Adisa, Olumide O.; Cox, Barry J.; Hill, James M.

    2012-05-01

    We survey various molecular structures which have been proposed as possible nanocontainers for methane storage. These are molecular structures that have been investigated through either experiments, molecular dynamics simulations or mathematical modelling. Computational simulation and mathematical modelling play an important role in predicting and verifying experimental outcomes, but both have their limitations. Even though recent advances have greatly improved computations, due to the large number of atoms and force field calculations involved, computational simulations can still be time consuming as compared to an instantaneous mathematical modelling approach. On the other hand, underlying an ideal mathematical model, there are many assumptions and approximations, but such modelling often reveals the key physical parameters and optimal configurations. Here, we review methane adsorption for three conventional nanostructures, namely graphite, single and multi-walled carbon nanotubes, and nanotube bundles (including interstitial and groove sites), and we survey methane adsorption in other molecular structures including metal organic frameworks. We also include an examination of minimum binding energies, equilibrium distances, gravimetric and volumetric uptakes, volume available for adsorption, as well as the effects of temperature and pressure on the adsorption of methane onto these molecular structures.

  12. Methane on the greenhouse agenda

    NASA Technical Reports Server (NTRS)

    Hogan, Kathleen B.; Hoffman, John S.; Thompson, Anne M.

    1991-01-01

    Options for reducing methane emissions, which could have a significant effect on global warming, are addressed. Emissions from landfills, coal mining, oil and natural gas systems, ruminants, animal wastes and wastewater, rice cultivation, and biomass burning are considered. Methods for implementing these emission reductions are discussed.

  13. Ductile flow of methane hydrate

    USGS Publications Warehouse

    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.

  14. Methane generation from waste materials

    DOEpatents

    Samani, Zohrab A.; Hanson, Adrian T.; Macias-Corral, Maritza

    2010-03-23

    An organic solid waste digester for producing methane from solid waste, the digester comprising a reactor vessel for holding solid waste, a sprinkler system for distributing water, bacteria, and nutrients over and through the solid waste, and a drainage system for capturing leachate that is then recirculated through the sprinkler system.

  15. Insights into Methane Formation Temperatures, Biogenic Methanogenesis, and Natural Methane Emissions from Clumped Isotopes

    NASA Astrophysics Data System (ADS)

    Douglas, P. M.; Stolper, D. A.; Walter Anthony, K. M.; Dallimore, S.; Paull, C. K.; Wik, M.; Crill, P. M.; Winterdahl, M.; Smith, D. A.; Luhmann, A. J.; Ding, K.; Seyfried, W. E., Jr.; Eiler, J. M.; Ponton, C.; Sessions, A. L.

    2015-12-01

    Multiply substituted isotopologues of methane are a valuable new tool for characterizing and understanding the source of methane in different Earth environments. Here we present methane clumped isotope results from natural gas wells, hydrothermal vents, marine and lacustrine methane seeps, and culture experiments. We observe a wide range of formation temperatures for thermogenic methane. Methane samples from low-maturity reservoirs indicate formation temperatures between 102-144° C, high-maturity conventional and shale gasses indicate temperatures between 158-246 °C, and thermogenic coal gases indicate temperatures between 174-267 °C. Methane formation temperatures generally correlate positively with δ13C, and negatively with gas wetness indices. Methane samples from a set of marine hydrothermal vents indicate a formation temperature of 290-350 °C. Methane sampled from subsurface and marine biogenic sources typically indicate temperatures consistent with the formation environment (0-64° C). In contrast, freshwater biogenic methane samples, and cultures of hydrogenotrophic and methylotrophic methanogens, express low levels of isotopic clumping inconsistent with their formation temperature. These data and complementary models suggest that kinetic isotope effects, likely modulated by rates and pathways of methanogenesis, affect biogenic methane in cultures and freshwater environments. Alternatively, non-equilibrium signatures may result from mixing of methane with widely differing δD and δ13C values. Analyses of biogenic methane emissions from lakes indicate a correlation between methane flux and non-equilibrium clumped isotope fractionations in a given lake. Results from large methane seeps in Alaskan lakes confirm that some seeps emit thermogenic methane, but also indicate that other seeps emit subsurface biogenic methane or variable mixtures of biogenic and thermogenic methane. These results point to diverse sources for large Arctic methane seeps.

  16. Milestone Report - Complete New Adsorbent Materials for Marine Testing to Demonstrate 4.5 g-U/kg Adsorbent

    SciTech Connect

    Janke, Christopher James; Das, Sadananda; Oyola, Yatsandra; Mayes, Richard T.; Saito, Tomonori; Brown, Suree; Gill, Gary; Kuo, Li-Jung; Wood, Jordana

    2014-08-01

    This report describes work on the successful completion of Milestone M2FT-14OR03100115 (8/20/2014) entitled, “Complete new adsorbent materials for marine testing to demonstrate 4.5 g-U/kg adsorbent”. This effort is part of the Seawater Uranium Recovery Program, sponsored by the U.S. Department of Energy, Office of Nuclear Energy, and involved the development of new adsorbent materials at the Oak Ridge National Laboratory (ORNL) and marine testing at the Pacific Northwest National Laboratory (PNNL). ORNL has recently developed two new families of fiber adsorbents that have demonstrated uranium adsorption capacities greater than 4.5 g-U/kg adsorbent after marine testing at PNNL. One adsorbent was synthesized by radiation-induced graft polymerization of itaconic acid and acrylonitrile onto high surface area polyethylene fibers followed by amidoximation and base conditioning. This fiber showed a capacity of 4.6 g-U/kg adsorbent in marine testing at PNNL. The second adsorbent was prepared by atom-transfer radical polymerization of t-butyl acrylate and acrylonitrile onto halide-functionalized round fibers followed by amidoximation and base hydrolysis. This fiber demonstrated uranium adsorption capacity of 5.4 g-U/kg adsorbent in marine testing at PNNL.

  17. Adsorption of carbon monoxide, carbon dioxide and methane on hexagonal boron nitride with high titanium coverage

    NASA Astrophysics Data System (ADS)

    Carrillo, I.; Ramírez, J. M.; Magaña, L. F.

    2015-07-01

    We used density functional theory and molecular dynamics to explore the adsorption of CO, CO2, and CH4 on a layer of h-BN with high titanium coverage. After optimization, we found that each titanium atom is located above each of the hexagons of the surface. We considered atmospheric pressure and 300 K. It is found that the first molecule is adsorbed and dissociated on the surface. The CO2 molecule is broken into O and CO. The methane molecule is physisorbed, and not dissociated. It is desorbed at 370 K.

  18. Analysis for the catalytic ignition of methane in a stagnation-point flow

    SciTech Connect

    Trevino, C.

    1999-03-01

    The catalytic ignition of a mixture of methane and air in a planar stagnation-point flow over a platinum foil is studied. The heterogeneous reaction mechanism is modeled with twelve heterogeneous reactions, including the adsorption processes of both reactants, the desorption kinetics of reactants and main products, and a set of surface reactions of the Hinshelwood-Langmuir type. The critical conditions for the catalytic ignition are found using high activation energy asymptotics of the desorption kinetics of the adsorbed reactant O(s). The analytical results are compared with published experimental data. The agreement is good, at least qualitatively.

  19. Understanding the Recent Methane Budget

    NASA Astrophysics Data System (ADS)

    Bruhwiler, L.; Dlugokencky, E. J.; Masarie, K.

    2010-12-01

    Anthropogenic sources are thought to account for roughly 2/3 of the global atmospheric methane budget, with natural sources making up the other 1/3. Emissions from wetlands are the largest contribution from natural sources while agriculture (rice and ruminants) and waste dominate anthropogenic emissions. Fugitive emissions from fossil fuel extraction are thought to make up about 20% of the global atmospheric methane budget. It is generally recognized that observed inter-annual variability in global network observations can be attributed to natural sources such as wetlands and biomass burning, while longer-term trends likely indicate changes in anthropogenic sources. Exceptions include an abrupt decrease in fossil fuel emissions in the early 1990s associated with political changes in the Former Soviet Union, and long-term trends in emissions from the Arctic due to a warming climate. The growth rate of global average atmospheric methane since the 1980s shows a steady decline until recent years when it started to increase again. Superimposed on these trends are episodes of higher growth rates. The cause of the recent increase is not currently well-understood, although climate-driven increases in wetland emissions likely played an important role, especially in the tropics. Recent increases in anthropogenic emissions, especially from rapidly expanding Asian economies cannot be ruled out. In addition, trends in the photochemical lifetime of methane must also be considered. In this paper we use both traditional data analysis of observations of methane and related species, and a state-of-the-art ensemble data assimilation system (CarbonTracker-CH4) to attribute methane variability and trends to anthropogenic and natural source processes. We pay particular attention to the Arctic, where some recent years have been the warmest on record, and to the tropics and the potential role of ENSO in driving variability of wetland emissions. Finally, we explore whether a signal in

  20. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    NASA Astrophysics Data System (ADS)

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-06-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix-a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30-47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3-35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.

  1. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    DOE PAGES

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-06-16

    In spite of the massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Here we show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases, and we usemore » molecular simulations to demonstrate it. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Finally, our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.« less

  2. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    PubMed Central

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-01-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release. PMID:27306967

  3. A feasible way to remove the heat during adsorptive methane storage.

    PubMed

    Gütlein, Stefan; Burkard, Christoph; Zeilinger, Johannes; Niedermaier, Matthias; Klumpp, Michael; Kolb, Veronika; Jess, Andreas; Etzold, Bastian J M

    2015-01-01

    Methane originating from biogas or natural gas is an attractive and environmentally friendly alternative to gasoline. Adsorption is seen as promising storage technology, but the heat released limits fast filling of these systems. Here a lab scale adsorptive methane storage tank, capable to study the temperature increase during fast filling, was realized. A variation of the filling time from 1 h to 31 s, showed a decrease of the storage capacity of 14% and temperature increase of 39.6 °C. The experimental data could be described in good accordance with a finite element simulation solving the transient mass, energy, and impulse balance. The simulation was further used to extrapolate temperature development in real sized car tanks and for different heat pipe scenarios, resulting in temperature rises of approximately 110 °C. It could be clearly shown, that with heat conductivity as solei mechanism the heat cannot be removed in acceptable time. By adding an outlet to the tank a feed flow cooling with methane as heat carrier was realized. This setup was proofed in simulation and lab scale experiments to be a promising technique for fast adsorbent cooling and can be crucial to leverage the full potential of adsorptive methane gas storage. PMID:25485691

  4. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    NASA Astrophysics Data System (ADS)

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-06-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.

  5. Nanostructural control of methane release in kerogen and its implications to wellbore production decline.

    PubMed

    Ho, Tuan Anh; Criscenti, Louise J; Wang, Yifeng

    2016-01-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix-a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30-47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3-35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release. PMID:27306967

  6. A feasible way to remove the heat during adsorptive methane storage.

    PubMed

    Gütlein, Stefan; Burkard, Christoph; Zeilinger, Johannes; Niedermaier, Matthias; Klumpp, Michael; Kolb, Veronika; Jess, Andreas; Etzold, Bastian J M

    2015-01-01

    Methane originating from biogas or natural gas is an attractive and environmentally friendly alternative to gasoline. Adsorption is seen as promising storage technology, but the heat released limits fast filling of these systems. Here a lab scale adsorptive methane storage tank, capable to study the temperature increase during fast filling, was realized. A variation of the filling time from 1 h to 31 s, showed a decrease of the storage capacity of 14% and temperature increase of 39.6 °C. The experimental data could be described in good accordance with a finite element simulation solving the transient mass, energy, and impulse balance. The simulation was further used to extrapolate temperature development in real sized car tanks and for different heat pipe scenarios, resulting in temperature rises of approximately 110 °C. It could be clearly shown, that with heat conductivity as solei mechanism the heat cannot be removed in acceptable time. By adding an outlet to the tank a feed flow cooling with methane as heat carrier was realized. This setup was proofed in simulation and lab scale experiments to be a promising technique for fast adsorbent cooling and can be crucial to leverage the full potential of adsorptive methane gas storage.

  7. The regulation of methane oxidation in soil

    NASA Technical Reports Server (NTRS)

    Mancinelli, R. L.

    1995-01-01

    The atmospheric concentration of methane, a greenhouse gas, has more than doubled during the past 200 years. Consequently, identifying the factors influencing the flux of methane into the atmosphere is becoming increasingly important. Methanotrophs, microaerophilic organisms widespread in aerobic soils and sediments, oxidize methane to derive energy and carbon for biomass. In so doing, they play an important role in mitigating the flux of methane into the atmosphere. Several physico-chemical factors influence rates of methane oxidation in soil, including soil diffusivity; water potential; and levels of oxygen, methane, ammonium, nitrate, nitrite, and copper. Most of these factors exert their influence through interactions with methane monooxygenase (MMO), the enzyme that catalyzes the reaction converting methane to methanol, the first step in methane oxidation. Although biological factors such as competition and predation undoubtedly play a role in regulating the methanotroph population in soils, and thereby limit the amount of methane consumed by methanotrophs, the significance of these factors is unknown. Obtaining a better understanding of the ecology of methanotrophs will help elucidate the mechanisms that regulate soil methane oxidation.

  8. NASA Applications of Molecular Adsorber Coatings

    NASA Technical Reports Server (NTRS)

    Abraham, Nithin S.

    2015-01-01

    The Molecular Adsorber Coating (MAC) is a new, innovative technology that was developed to reduce the risk of molecular contamination on spaceflight applications. Outgassing from materials, such as plastics, adhesives, lubricants, silicones, epoxies, and potting compounds, pose a significant threat to the spacecraft and the lifetime of missions. As a coating made of highly porous inorganic materials, MAC offers impressive adsorptive capabilities that help capture and trap contaminants. Past research efforts have demonstrated the coating's promising adhesion performance, optical properties, acoustic durability, and thermal stability. These results advocate its use near or on surfaces that are targeted by outgassed materials, such as internal optics, electronics, detectors, baffles, sensitive instruments, thermal control coatings, and vacuum chamber test environments. The MAC technology has significantly progressed in development over the recent years. This presentation summarizes the many NASA spaceflight applications of MAC and how the coatings technology has been integrated as a mitigation tool for outgassed contaminants. For example, this sprayable paint technology has been beneficial for use in various vacuum chambers for contamination control and hardware bake-outs. The coating has also been used in small instrument cavities within spaceflight instrument for NASA missions.

  9. Morphological characterization of furfuraldehyde resins adsorbents

    SciTech Connect

    Sanchez, R.; Monteiro, S.N.; D`Almeida, J.R.

    1996-12-31

    Sugar cane is one of the most traditional plantation cultivated crops in large areas in Brazil. The State University of the North of Rio de Janeiro, UENF, is currently engaged in a program aimed to exploit the potentialities of sugar cane industry as a self sustained non-polluting enterprise. One of the projects being carried out at the UENF is the transformation of sugar cane bagasse in precursor materials for the industry of furan derivatives such as the furfuraldehyde resins obtained by acid catalysis. The possibility of employing acid catalyzed furfuraldehyde resins as selective adsorbents has arisen during a comprehensive study of physical-chemical adsorption properties of these materials. The morphology of these resins depend on the synthesis method. Scanning Electron Microscopic studies of these materials which were synthesized, in bulk (FH-M) and solution (FH-D), showed differences in surface density and particle size. Using mercury porosimeter techniques and BET adsorption methods, it was found different pore size distributions and a decrement in surface area when solvent was employed in the synthesis process. By thermogravimetric analysis it was found similar weight losses (6%) of water adsorption and a small differences in thermal stabilities.

  10. 40 CFR 86.419-2006 - Engine displacement, motorcycle classes.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 19 2012-07-01 2012-07-01 false Engine displacement, motorcycle... displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using nominal engine values... reference in § 86.1). (2) For rotary engines, displacement means the maximum volume of a combustion...

  11. 40 CFR 86.419-2006 - Engine displacement, motorcycle classes.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 19 2013-07-01 2013-07-01 false Engine displacement, motorcycle... displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using nominal engine values... reference in § 86.1). (2) For rotary engines, displacement means the maximum volume of a combustion...

  12. 40 CFR 86.419-2006 - Engine displacement, motorcycle classes.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 19 2014-07-01 2014-07-01 false Engine displacement, motorcycle... displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using nominal engine values... reference in § 86.1). (2) For rotary engines, displacement means the maximum volume of a combustion...

  13. Boron nitride as a selective gas adsorbent

    SciTech Connect

    Janik, J.F.; Ackerman, W.C.; Paine, R.T.; Hua, D.W.; Maskara, A.; Smith, D.M. )

    1994-02-01

    A series of eight porous boron nitride materials with nitrogen/BET surface areas of 437-712 m[sup 2]/g have been produced using polymeric precursors varied by systematic synthesis modifications. All samples exhibit type I isotherms indicating that a majority of the porosity occurs in pores with radius less than 1.0 nm. Carbon dioxide adsorption at 273 K was analyzed using the Dubinin-Radushkevich (D-R) and Dubinin-Astakov (D-A) equations. Significant differences between BET/N[sub 2] and D-R/CO[sub 2] surface areas are observed. Adsorption of carbon dioxide and methane is measured at 273 K over the pressure range of 0-800 Torr, and significant differences in adsorption selectivity are observed. Although all eight samples have similar BET surface areas, the carbon dioxide uptake at 273 K and 800 Torr varies from 9.5 to 125 cm[sup 3]/g. Differences in the chemical and physical structure of the samples are probed with Fourier transform IR, X-ray diffraction, and small angle X-ray scattering measurements. CH[sub 4]/CO[sub 2] selectivity correlates with both the radius of gyration obtained from SAXS and the D-A coefficient from CO[sub 2] adsorption. 16 refs., 9 figs., 1 tab.

  14. Laboratory study of the displacement coalbed CH4 process and efficiency of CO2 and N2 injection.

    PubMed

    Wang, Liguo; Cheng, Yuanping; Wang, Yongkang

    2014-01-01

    ECBM displacement experiments are a direct way to observe the gas displacement process and efficiency by inspecting the produced gas composition and flow rate. We conducted two sets of ECBM experiments by injecting N2 and CO2 through four large parallel specimens (300 × 50 × 50 mm coal briquette). N2 or CO2 is injected at pressures of 1.5, 1.8, and 2.2 MPa and various crustal stresses. The changes in pressure along the briquette and the concentration of the gas mixture flowing out of the briquette were analyzed. Gas injection significantly enhances CBM recovery. Experimental recoveries of the original extant gas are in excess of 90% for all cases. The results show that the N2 breakthrough occurs earlier than the CO2 breakthrough. The breakthrough time of N2 is approximately 0.5 displaced volumes. Carbon dioxide, however, breaks through at approximately 2 displaced volumes. Coal can adsorb CO2, which results in a slower breakthrough time. In addition, ground stress significantly influences the displacement effect of the gas injection.

  15. Laboratory Study of the Displacement Coalbed CH4 Process and Efficiency of CO2 and N2 Injection

    PubMed Central

    Wang, Liguo; Wang, Yongkang

    2014-01-01

    ECBM displacement experiments are a direct way to observe the gas displacement process and efficiency by inspecting the produced gas composition and flow rate. We conducted two sets of ECBM experiments by injecting N2 and CO2 through four large parallel specimens (300 × 50 × 50 mm coal briquette). N2 or CO2 is injected at pressures of 1.5, 1.8, and 2.2 MPa and various crustal stresses. The changes in pressure along the briquette and the concentration of the gas mixture flowing out of the briquette were analyzed. Gas injection significantly enhances CBM recovery. Experimental recoveries of the original extant gas are in excess of 90% for all cases. The results show that the N2 breakthrough occurs earlier than the CO2 breakthrough. The breakthrough time of N2 is approximately 0.5 displaced volumes. Carbon dioxide, however, breaks through at approximately 2 displaced volumes. Coal can adsorb CO2, which results in a slower breakthrough time. In addition, ground stress significantly influences the displacement effect of the gas injection. PMID:24741346

  16. Effect of the internal motions of an adsorbate on the characteristics of adsorption for structurally heterogenous surfaces of slit-like pores

    NASA Astrophysics Data System (ADS)

    Tovbin, Yu. K.; Zaitseva, E. S.; Rabinovich, A. B.

    2016-01-01

    The effect of internal motions of an adsorbate on the local characteristics of adsorption and layering phase diagrams are studied for structurally heterogeneous surfaces of slit-like pores. A molecular model describing adsorbate distributions inside slit-like pores, which is based on discrete distribution functions (lattice gas model), is used for the calculation. Molecular distributions are calculated by the Lennard-Jones potential (12-6) in a quasi-chemical approximation reflecting the effects of direct correlations of interacting particles and for the combined interaction of an adsorbate with walls in the average potential approximation (9-3) and the short-range Lennard-Jones potential for structurally heterogeneous surface areas. The conclusion is made that internal motions reflect the vibrational motion of molecules within a modified quasi-dimer model and a displacement of the adsorbate during its translational motion inside cells. It was found that the taking into account of internal motions decreases the critical temperature of adsorbate layering in slit-like pores.

  17. Extension-Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption

    SciTech Connect

    Anna Lee Tonkovich

    2006-04-01

    The purpose of this project is to develop a cost effective technology for upgrading coal mine methane to natural gas pipeline quality. Nitrogen rejection is the most costly step with conventional technology and emerging competitive technology. Significant cost reductions to this step will allow for the cost effective capture and utilization of this otherwise potent greenhouse gas. The proposed approach is based on the microchannel technology platform that Velocys is developing to commercialize compact and cost efficient chemical processing technology. For this application, ultra fast thermal swing adsorption is enabled by the very high rates of heat transfer enabled by microchannels. Natural gas upgrading systems have six main unit operations: feed compressor, dehydration unit, nitrogen rejection unit, deoxygenator, carbon dioxide scrubber, and a sales compressor. The NRU is the focus of the development program, and a bench-scale demonstration has been initiated. The Velocys NRU system targets producing methane with greater than 96% purity and at least 90% recovery for final commercial operation. A preliminary cost analysis of the methane upgrading system, including the Velocys NRU, suggests that costs below $2.00 per million (MM) BTU methane may be achieved. The cost for a conventional methane upgrading system is well above $2.30 per MM BTU, as benchmarked in an Environmental Protection Agency study. Initial performance results for the Velocys TSA technology were promising. Velocys has also completed initial discussions with several prospective users of the technology and received positive market feedback. Some of the factors that create an attractive opportunity for the technology include the sustained high prices for natural gas, the emerging system of carbon credits, and continued focus on reducing coal mine emissions. While market interest has been confirmed, improvements and optimization are necessary to move the technology to a point that will enable

  18. Estimation of methane emission flux at landfill surface using laser methane detector: Influence of gauge pressure.

    PubMed

    Park, Jin-Kyu; Kang, Jong-Yun; Lee, Nam-Hoon

    2016-08-01

    The aim of this study was to investigate the possibility of measuring methane emission fluxes, using surface methane concentration and gauge pressure, by analyzing the influence of gauge pressure on the methane emission flux and the surface methane concentration, as well as the correlation between the methane emission flux and surface methane concentrations. The surface methane concentration was measured using a laser methane detector. Our results show a positive linear relationship between the surface methane concentration and the methane emission flux. Furthermore, the methane emission flux showed a positive linear relationship with the gauge pressure; this implies that when the surface methane concentration and the surface gauge pressure are measured simultaneously, the methane emission flux can be calculated using Darcy's law. A decrease in the vertical permeability was observed when the gauge pressure was increased, because reducing the vertical permeability may lead to a reduced landfill gas emission to the atmosphere, and landfill gas would be accumulated inside the landfill. Finally, this method is simple and can allow for a greater number of measurements during a relatively shorter period. Thus, it provides a better representation of the significant space and time variations in methane emission fluxes. PMID:27401161

  19. Estimation of methane emission flux at landfill surface using laser methane detector: Influence of gauge pressure.

    PubMed

    Park, Jin-Kyu; Kang, Jong-Yun; Lee, Nam-Hoon

    2016-08-01

    The aim of this study was to investigate the possibility of measuring methane emission fluxes, using surface methane concentration and gauge pressure, by analyzing the influence of gauge pressure on the methane emission flux and the surface methane concentration, as well as the correlation between the methane emission flux and surface methane concentrations. The surface methane concentration was measured using a laser methane detector. Our results show a positive linear relationship between the surface methane concentration and the methane emission flux. Furthermore, the methane emission flux showed a positive linear relationship with the gauge pressure; this implies that when the surface methane concentration and the surface gauge pressure are measured simultaneously, the methane emission flux can be calculated using Darcy's law. A decrease in the vertical permeability was observed when the gauge pressure was increased, because reducing the vertical permeability may lead to a reduced landfill gas emission to the atmosphere, and landfill gas would be accumulated inside the landfill. Finally, this method is simple and can allow for a greater number of measurements during a relatively shorter period. Thus, it provides a better representation of the significant space and time variations in methane emission fluxes.

  20. Methane clathrates in the solar system.

    PubMed

    Mousis, Olivier; Chassefière, Eric; Holm, Nils G; Bouquet, Alexis; Waite, Jack Hunter; Geppert, Wolf Dietrich; Picaud, Sylvain; Aikawa, Yuri; Ali-Dib, Mohamad; Charlou, Jean-Luc; Rousselot, Philippe

    2015-04-01

    We review the reservoirs of methane clathrates that may exist in the different bodies of the Solar System. Methane was formed in the interstellar medium prior to having been embedded in the protosolar nebula gas phase. This molecule was subsequently trapped in clathrates that formed from crystalline water ice during the cooling of the disk and incorporated in this form into the building blocks of comets, icy bodies, and giant planets. Methane clathrates may play an important role in the evolution of planetary atmospheres. On Earth, the production of methane in clathrates is essentially biological, and these compounds are mostly found in permafrost regions or in the sediments of continental shelves. On Mars, methane would more likely derive from hydrothermal reactions with olivine-rich material. If they do exist, martian methane clathrates would be stable only at depth in the cryosphere and sporadically release some methane into the atmosphere via mechanisms that remain to be determined. In the case of Titan, most of its methane probably originates from the protosolar nebula, where it would have been trapped in the clathrates agglomerated by the satellite's building blocks. Methane clathrates are still believed to play an important role in the present state of Titan. Their presence is invoked in the satellite's subsurface as a means of replenishing its atmosphere with methane via outgassing episodes. The internal oceans of Enceladus and Europa also provide appropriate thermodynamic conditions that allow formation of methane clathrates. In turn, these clathrates might influence the composition of these liquid reservoirs. Finally, comets and Kuiper Belt Objects might have formed from the agglomeration of clathrates and pure ices in the nebula. The methane observed in comets would then result from the destabilization of clathrate layers in the nuclei concurrent with their approach to perihelion. Thermodynamic equilibrium calculations show that methane-rich clathrate

  1. Methane clathrates in the solar system.

    PubMed

    Mousis, Olivier; Chassefière, Eric; Holm, Nils G; Bouquet, Alexis; Waite, Jack Hunter; Geppert, Wolf Dietrich; Picaud, Sylvain; Aikawa, Yuri; Ali-Dib, Mohamad; Charlou, Jean-Luc; Rousselot, Philippe

    2015-04-01

    We review the reservoirs of methane clathrates that may exist in the different bodies of the Solar System. Methane was formed in the interstellar medium prior to having been embedded in the protosolar nebula gas phase. This molecule was subsequently trapped in clathrates that formed from crystalline water ice during the cooling of the disk and incorporated in this form into the building blocks of comets, icy bodies, and giant planets. Methane clathrates may play an important role in the evolution of planetary atmospheres. On Earth, the production of methane in clathrates is essentially biological, and these compounds are mostly found in permafrost regions or in the sediments of continental shelves. On Mars, methane would more likely derive from hydrothermal reactions with olivine-rich material. If they do exist, martian methane clathrates would be stable only at depth in the cryosphere and sporadically release some methane into the atmosphere via mechanisms that remain to be determined. In the case of Titan, most of its methane probably originates from the protosolar nebula, where it would have been trapped in the clathrates agglomerated by the satellite's building blocks. Methane clathrates are still believed to play an important role in the present state of Titan. Their presence is invoked in the satellite's subsurface as a means of replenishing its atmosphere with methane via outgassing episodes. The internal oceans of Enceladus and Europa also provide appropriate thermodynamic conditions that allow formation of methane clathrates. In turn, these clathrates might influence the composition of these liquid reservoirs. Finally, comets and Kuiper Belt Objects might have formed from the agglomeration of clathrates and pure ices in the nebula. The methane observed in comets would then result from the destabilization of clathrate layers in the nuclei concurrent with their approach to perihelion. Thermodynamic equilibrium calculations show that methane-rich clathrate

  2. Measurement of gas quantities by liquid displacement.

    NASA Technical Reports Server (NTRS)

    Christian, J. D.

    1973-01-01

    Derivation of equations relating the different variables involved in gas quantity measurements by liquid displacement from a Mariotte flask. The results are used to elucidate design criteria and operational procedures required for the realization of various degrees of desired accuracy down to 0.01%.

  3. RECOVERY OF METAL USING ALUMINUM DISPLACEMENT

    EPA Science Inventory

    The removal of typical metals (Cu, Pb, Sn, Ni) from printed circuit and metal finishing waste streams was evaluated using displacement with aluminum. he metal is recovered as non-hazardous metal particles and can be recycled by smelting. n acceptable aluminum metal configuration ...

  4. The Needs of Displaced Homemakers in California.

    ERIC Educational Resources Information Center

    Far West Lab. for Educational Research and Development, San Francisco, CA.

    The seven most frequently mentioned needs of displaced homemakers are (1) personal counseling; (2) career or vocational counseling; (3) further education or training; (4) information, outreach, publicity; (5) temporary financial or other support during training; (6) jobs and job development; and (7) awareness of own needs. Active publicity and…

  5. Stability of Helium Clusters during Displacement Cascades

    SciTech Connect

    Yang, Li; Zu, Xiaotao T.; Xiao, H. Y.; Gao, Fei; Heinisch, Howard L.; Kurtz, Richard J.; Wang, Zhiguo; Liu, K. Z.

    2007-02-01

    The interaction of displacement cascades with helium-vacancy clusters is investigated using molecular dynamics simulations. The He-vacancy clusters initially consist of 20 vacancies with a Helium-to-vacancy ratio ranging from 0.2 to 3. The primary knock-on atom (PKA) energy, Ep, varies from 2 keV to 10 keV, and the PKA direction is chosen such that a displacement cascade is able to directly interact with a helium-vacancy cluster. The simulation results show that the effect of displacement cascades on a helium-vacancy cluster strongly depends on both the helium-to-vacancy ratio and the PKA energy. For the same PKA energy, the size of helium-vacancy clusters increases with the He/V ratio, but for the same ratio, the cluster size changes more significantly with increasing PKA energy. It has been observed that the He-vacancy clusters can be dissolved when the He/V ratio less than 1, but they are able to re-nucleate during the thermal spike phase, forming small He-V nuclei. When the He/V ratio is larger than 1, the He-V clusters can absorb a number of vacancies produced by displacement cascades, forming larger He-V clusters. These results are discussed in terms of PKA energy, helium-to-vacancy ratio, number of vacancies produced by cascades, and mobility of helium atoms.

  6. Displacement Damage in Bipolar Linear Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Rax, B. G.; Johnston, A. H.; Miyahira, T.

    2000-01-01

    Although many different processes can be used to manufacture linear integrated circuits, the process that is used for most circuits is optimized for high voltage -- a total power supply voltage of about 40 V -- and low cost. This process, which has changed little during the last twenty years, uses lateral and substrate p-n-p transistors. These p-n-p transistors have very wide base regions, increasing their sensitivity to displacement damage from electrons and protons. Although displacement damage effects can be easily treated for individual transistors, the net effect on linear circuits can be far more complex because circuit operation often depends on the interaction of several internal transistors. Note also that some circuits are made with more advanced processes with much narrower base widths. Devices fabricated with these newer processes are not expected to be significantly affected by displacement damage for proton fluences below 1 x 10(exp 12) p/sq cm. This paper discusses displacement damage in linear integrated circuits with more complex failure modes than those exhibited by simpler devices, such as the LM111 comparator, where the dominant response mode is gain degradation of the input transistor. Some circuits fail catastrophically at much lower equivalent total dose levels compared to tests with gamma rays. The device works satisfactorily up to nearly 1 Mrad(Si) when it is irradiated with gamma rays, but fails catastrophically between 50 and 70 krad(Si) when it is irradiated with protons.

  7. Retraining Displaced Workers--Barriers and Facilitators.

    ERIC Educational Resources Information Center

    Wolansky, William D.

    Although plant closings and layoffs have been happening for a long time, today's recessions, major changes in the structure of the economy, and a tight job market have combined to make plant closings a more serious problem. Workers are faced with unemployment from both traditional labor-displacing changes, such as the increasing use of robotics;…

  8. Insect Wing Displacement Measurement Using Digital Holography

    SciTech Connect

    Aguayo, Daniel D.; Mendoza Santoyo, Fernando; Torre I, Manuel H. de la; Caloca Mendez, Cristian I.

    2008-04-15

    Insects in flight have been studied with optical non destructive techniques with the purpose of using meaningful results in aerodynamics. With the availability of high resolution and large dynamic range CCD sensors the so called interferometric digital holographic technique was used to measure the surface displacement of in flight insect wings, such as butterflies. The wings were illuminated with a continuous wave Verdi laser at 532 nm, and observed with a CCD Pixelfly camera that acquire images at a rate of 11.5 frames per second at a resolution of 1392x1024 pixels and 12 Bit dynamic range. At this frame rate digital holograms of the wings were captured and processed in the usual manner, namely, each individual hologram is Fourier processed in order to find the amplitude and phase corresponding to the digital hologram. The wings displacement is obtained when subtraction between two digital holograms is performed for two different wings position, a feature applied to all consecutive frames recorded. The result of subtracting is seen as a wrapped phase fringe pattern directly related to the wing displacement. The experimental data for different butterfly flying conditions and exposure times are shown as wire mesh plots in a movie of the wings displacement.

  9. The Income Losses of Displaced Workers

    ERIC Educational Resources Information Center

    Hijzen, Alexander; Upward, Richard; Wright, Peter W.

    2010-01-01

    We use a new, matched worker-firm dataset for the United Kingdom to estimate the income loss resulting from firm closure and mass layoffs. We track workers for up to nine years after the displacement event, and the availability of predisplacement characteristics allows us to implement difference-in-differences estimators using propensity score…

  10. Variable-Displacement Hydraulic Drive Unit

    NASA Technical Reports Server (NTRS)

    Lang, D. J.; Linton, D. J.; Markunas, A.

    1986-01-01

    Hydraulic power controlled through multiple feedback loops. In hydraulic drive unit, power closely matched to demand, thereby saving energy. Hydraulic flow to and from motor adjusted by motor-control valve connected to wobbler. Wobbler angle determines motor-control-valve position, which in turn determines motor displacement. Concept applicable to machine tools, aircraft controls, and marine controls.

  11. A Personal Appearance Program for Displaced Homemakers.

    ERIC Educational Resources Information Center

    Fiore, Ann Marie; De Long, Marilyn Revell

    1990-01-01

    A career counseling program evaluated the self-esteem of 28 displaced homemakers, then presented 3 sessions on the importance of personal appearance in hiring practices, wardrobe management, nonverbal communication, professional image, and self-concept. Analysis of participant evaluations indicated improved levels of control and confidence and…

  12. Britain's Redundancy Payments for Displaced Workers.

    ERIC Educational Resources Information Center

    Root, Lawrence S.

    1987-01-01

    The Redundancy Payments Act of 1965 established the idea that an employee has property rights to a job based on years of company service. It instituted an entitlement program for displaced workers sponsored by firms and the government. The British layoff situtation differs from that of the United States. (Author/CH)

  13. Ko Displacement Theory for Structural Shape Predictions

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    2010-01-01

    The development of the Ko displacement theory for predictions of structure deformed shapes was motivated in 2003 by the Helios flying wing, which had a 247-ft (75-m) wing span with wingtip deflections reaching 40 ft (12 m). The Helios flying wing failed in midair in June 2003, creating the need to develop new technology to predict in-flight deformed shapes of unmanned aircraft wings for visual display before the ground-based pilots. Any types of strain sensors installed on a structure can only sense the surface strains, but are incapable to sense the overall deformed shapes of structures. After the invention of the Ko displacement theory, predictions of structure deformed shapes could be achieved by feeding the measured surface strains into the Ko displacement transfer functions for the calculations of out-of-plane deflections and cross sectional rotations at multiple locations for mapping out overall deformed shapes of the structures. The new Ko displacement theory combined with a strain-sensing system thus created a revolutionary new structure- shape-sensing technology.

  14. Carbon dioxide pressure swing adsorption process using modified alumina adsorbents

    DOEpatents

    Gaffney, T.R.; Golden, T.C.; Mayorga, S.G.; Brzozowski, J.R.; Taylor, F.W.

    1999-06-29

    A pressure swing adsorption process for absorbing CO[sub 2] from a gaseous mixture containing CO[sub 2] comprises introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100 C and 500 C to adsorb CO[sub 2] to provide a CO[sub 2] laden alumina adsorbent and a CO[sub 2] depleted gaseous mixture and contacting the CO[sub 2] laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO[sub 2] from the CO[sub 2] laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100 C and 600 C, is not degraded by high concentrations of water under process operating conditions. 1 fig.

  15. Carbon dioxide pressure swing adsorption process using modified alumina adsorbents

    DOEpatents

    Gaffney, Thomas Richard; Golden, Timothy Christopher; Mayorga, Steven Gerard; Brzozowski, Jeffrey Richard; Taylor, Fred William

    1999-01-01

    A pressure swing adsorption process for absorbing CO.sub.2 from a gaseous mixture containing CO.sub.2 comprising introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100.degree. C. and 500.degree. C. to adsorb CO.sub.2 to provide a CO.sub.2 laden alumina adsorbent and a CO.sub.2 depleted gaseous mixture and contacting the CO.sub.2 laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO.sub.2 from the CO.sub.2 laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100.degree. C. and 600.degree. C., is not degraded by high concentrations of water under process operating conditions.

  16. From adsorption to condensation: the role of adsorbed molecular clusters.

    PubMed

    Yaghoubian, Sima; Zandavi, Seyed Hadi; Ward, C A

    2016-08-01

    The adsorption of heptane vapour on a smooth silicon substrate with a lower temperature than the vapour is examined analytically and experimentally. An expression for the amount adsorbed under steady state conditions is derived from the molecular cluster model of the adsorbate that is similar to the one used to derive the equilibrium Zeta adsorption isotherm. The amount adsorbed in each of a series of steady experiments is measured using a UV-vis interferometer, and gives strong support to the amount predicted to be adsorbed. The cluster distribution is used to predict the subcooling temperature required for the adsorbed vapour to make a disorder-order phase transition to become an adsorbed liquid, and the subcooling temperature is found to be 2.7 ± 0.4 K. The continuum approach for predicting the thickness of the adsorbed liquid film originally developed by Nusselt is compared with that measured and is found to over-predict the thickness by three-orders of magnitude. PMID:27426944

  17. Mercury adsorption properties of sulfur-impregnated adsorbents

    USGS Publications Warehouse

    Hsi, N.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

    2002-01-01

    Carbonaceous and noncarbonaceous adsorbents were impregnated with elemental sulfur to evaluate the chemical and physical properties of the adsorbents and their equilibrium mercury adsorption capacities. Simulated coal combustion flue gas conditions were used to determine the equilibrium adsorption capacities for Hg0 and HgCl2 gases to better understand how to remove mercury from gas streams generated by coal-fired utility power plants. Sulfur was deposited onto the adsorbents by monolayer surface deposition or volume pore filling. Sulfur impregnation increased the total sulfur content and decreased the total and micropore surface areas and pore volumes for all of the adsorbents tested. Adsorbents with sufficient amounts of active adsorption sites and sufficient microporous structure had mercury adsorption capacities up to 4,509 ??g Hg/g adsorbent. Elemental sulfur, organic sulfur, and sulfate were formed on the adsorbents during sulfur impregnation. Correlations were established with R2>0.92 between the equilibrium Hg0/HgCl2 adsorption capacities and the mass concentrations of elemental and organic sulfur. This result indicates that elemental and organic sulfur are important active adsorption sites for Hg0 and HgCl2.

  18. Novel adhesion properties of irreversibly adsorbed polymer chains

    NASA Astrophysics Data System (ADS)

    Chen, Zhizhao; Sen, Mani; Cheung, Justin; Barkley, Deborah; Jiang, Naisheng; Zeng, Wenduo; Endoh, Maya K.; Koga, Tadanori

    The stability of thin polymer films on solids is of vital interest in traditional technologies and in new emerging nanotechnologies. We recently found that nanoscale structures of polymer chains adsorbed onto a silicon (Si) substrate (``adsorbed nanolayers'') play a crucial role in the thermal stability of the film. To understand the adhesion mechanism at the adsorbed polymer-free polymer interface, we mimicked the interface by preparing bilayers where a 200 nm-thick polymer film and an adsorbed nanolayer, both prepared on Si, were pressed together at high temperature. The bilayers were then subjected to an adhesion test by measuring the critical normal force required to separate the two films. Polystyrene was used as a model. The results are intriguing as they show an absence of adhesion between the ``flattened'' adsorbed chains, which lie flat on the solid, and the chemically identical free chains. On the other hand, the ``loosely adsorbed'' polymer chains, which are formed as a result of limited adsorption space on the solid surface, do display a degree of adhesion with the bulk polymer. We postulate that the loosely adsorbed chains act as ``connectors'' which promote adhesion effectively across the solid-polymer interface. We acknowledge the financial support from NSF Grant No. CMMI-1332499.

  19. Monte-Carlo simulations of methane/carbon dioxide and ethane/carbon dioxide mixture adsorption in zeolites and comparison with matrix treatment of statistical mechanical lattice model

    NASA Astrophysics Data System (ADS)

    Dunne, Lawrence J.; Furgani, Akrem; Jalili, Sayed; Manos, George

    2009-05-01

    Adsorption isotherms have been computed by Monte-Carlo simulation for methane/carbon dioxide and ethane/carbon dioxide mixtures adsorbed in the zeolite silicalite. These isotherms show remarkable differences with the ethane/carbon dioxide mixtures displaying strong adsorption preference reversal at high coverage. To explain the differences in the Monte-Carlo mixture isotherms an exact matrix calculation of the statistical mechanics of a lattice model of mixture adsorption in zeolites has been made. The lattice model reproduces the essential features of the Monte-Carlo isotherms, enabling us to understand the differing adsorption behaviour of methane/carbon dioxide and ethane/carbon dioxide mixtures in zeolites.

  20. The use of a displacement device negatively affects the performance of dogs (Canis familiaris) in visible object displacement tasks

    PubMed Central

    Müller, Corsin A.; Riemer, Stefanie; Range, Friederike; Huber, Ludwig

    2014-01-01

    Visible and invisible displacement tasks have been used widely for comparative studies of animals’ understanding of object permanence, with evidence accumulating that some species can solve invisible displacement tasks and thus reach Piagetian stage 6 of object permanence. In contrast, dogs appear to rely on associative cues, such as the location of the displacement device, during invisible displacement tasks. It remains unclear, however, whether dogs, and other species that failed in invisible displacement tasks, do so due to their inability to form a mental representation of the target object, or simply due to the involvement of a more salient but potentially misleading associative cue, the displacement device. Here we show that the use of a displacement device impairs the performance of dogs also in visible displacement tasks: their search accuracy was significantly lower when a visible displacement was performed with a displacement device, and only two of initially 42 dogs passed the sham-baiting control conditions. The negative influence of the displacement device in visible displacement tasks may be explained by strong associative cues overriding explicit information about the target object’s location, reminiscent of an overshadowing effect, and/or object individuation errors as the target object is placed within the displacement device and moves along a spatiotemporally identical trajectory. Our data suggest that a comprehensive appraisal of a species’ performance in object permanence tasks should include visible displacement tasks with the same displacement device used in invisible displacements, which typically has not been done in the past. PMID:24611641

  1. Turbulent burning rates of methane and methane-hydrogen mixtures

    SciTech Connect

    Fairweather, M.; Ormsby, M.P.; Sheppard, C.G.W.; Woolley, R.

    2009-04-15

    Methane and methane-hydrogen (10%, 20% and 50% hydrogen by volume) mixtures have been ignited in a fan stirred bomb in turbulence and filmed using high speed cine schlieren imaging. Measurements were performed at 0.1 MPa (absolute) and 360 K. A turbulent burning velocity was determined for a range of turbulence velocities and equivalence ratios. Experimental laminar burning velocities and Markstein numbers were also derived. For all fuels the turbulent burning velocity increased with turbulence velocity. The addition of hydrogen generally resulted in increased turbulent and laminar burning velocity and decreased Markstein number. Those flames that were less sensitive to stretch (lower Markstein number) burned faster under turbulent conditions, especially as the turbulence levels were increased, compared to stretch-sensitive (high Markstein number) flames. (author)

  2. The Methane to Markets Coal Mine Methane Subcommittee meeting

    SciTech Connect

    2008-07-01

    The presentations (overheads/viewgraphs) include: a report from the Administrative Support Group; strategy updates from Australia, India, Italy, Mexico, Nigeria, Poland and the USA; coal mine methane update and IEA's strategy and activities; the power of VAM - technology application update; the emissions trading market; the voluntary emissions reduction market - creating profitable CMM projects in the USA; an Italian perspective towards a zero emission strategies; and the wrap-up and summary.

  3. Surface enhanced Raman scattering of pyrazole adsorbed on silver colloids

    NASA Astrophysics Data System (ADS)

    Muniz-Miranda, Maurizio; Neto, Natale; Sbrana, Giuseppe

    1999-05-01

    SERS spectra of pyrazole adsorbed on silver hydrosol at different pH values and on silver colloidal substrate deposited on filters were obtained and interpreted on the basis of the existence of three forms in equilibrium, cationic, neutral and anionic. SERS data indicate that the neutral molecule is preferentially adsorbed in acidic environment, pyrazolide anion is instead favoured over all the other pH values. Addition of chloride anions induces the formation of reaction products when pyrazole is adsorbed on silver hydrosols, while this effect is missing on dry silver substrate.

  4. Greenhouse gas impacts of natural gas: Influence of deployment choice, methane leak rate, and methane GWP

    NASA Astrophysics Data System (ADS)

    Cohan, D. S.

    2015-12-01

    Growing supplies of natural gas have heightened interest in the net impacts of natural gas on climate. Although its production and consumption result in greenhouse gas emissions, natural gas most often substitutes for other fossil fuels whose emission rates may be higher. Because natural gas can be used throughout the sectors of the energy economy, its net impacts on greenhouse gas emissions will depend not only on the leak rates of production and distribution, but also on the use for which natural gas is substituted. Here, we present our estimates of the net greenhouse gas emissions impacts of substituting natural gas for other fossil fuels for five purposes: light-duty vehicles, transit buses, residential heating, electricity generation, and export for electricity generation overseas. Emissions are evaluated on a fuel cycle basis, from production and transport of each fuel through end use combustion, based on recent conditions in the United States. We show that displacement of existing coal-fired electricity and heating oil furnaces yield the largest reductions in emissions. The impact of compressed natural gas replacing petroleum-based vehicles is highly uncertain, with the sign of impact depending on multiple assumptions. Export of liquefied natural gas for electricity yields a moderate amount of emissions reductions. We further show how uncertainties in upstream emission rates for natural gas and in the global warming potential of methane influence the net greenhouse gas impacts. Our presentation will make the case that how natural gas is deployed is crucial to determining how it will impact climate.

  5. Mysterious Lattice Rotations in Adsorbed Monolayers

    NASA Astrophysics Data System (ADS)

    Diehl, Renee D.

    1997-03-01

    Lattice rotations due to a mismatch in structure have been observed in film growth for many years, probably beginning in the 1930's with the Nishiyama-Wasserman and Kurdjumov-Sachs orientations observed when fcc(111) films grow on bcc(110) surfaces, or vice versa. Early analysis of this problem was carried out with the aid of Moiré patterns and the observation that the preferred lattice orientations are those which maximize the Moiré fringe spacing. Later energy calculations indicated that the structures which were predicted by the the Moiré technique actually do correspond to energy minima. Epitaxial rotation in adsorbed monolayers is a conceptually simpler problem since in principle it involves only two planes of atoms, and it was first observed in 1977 for Ar on a graphite surface(C. G. Shaw, M. D. Chinn, S. C. Fain, Jr. Phys. Rev. Lett. 41 (1978) 955.). This observation came only a few months after a new theory, based on the expected elastic behavior of an overlayer, was developed by A. D. Novaco and J. P. McTague(A. D. Novaco and J. P. McTague, Phys. Rev. Lett. 38 (1977) 1286.), and the agreement with the experimental results was remarkable. It was later shown that a few symmetry principles similar to those used for the film growth studies sometimes can also predict the observed structures. However, the situation for incommensurate layers physisorbed on metal surfaces currently looks bleak. None of the existing theories or models appears to describe the experimental results. New data for physisorbed gases on metal surfaces will be presented, along with some half-baked (and probably wrong) ideas for what might be happening. This work was supported by NSF.

  6. Attributing Atmospheric Methane to Anthropogenic Emission Sources.

    PubMed

    Allen, David

    2016-07-19

    Methane is a greenhouse gas, and increases in atmospheric methane concentration over the past 250 years have driven increased radiative forcing of the atmosphere. Increases in atmospheric methane concentration since 1750 account for approximately 17% of increases in radiative forcing of the atmosphere, and that percentage increases by approximately a factor of 2 if the effects of the greenhouse gases produced by the atmospheric reactions of methane are included in the assessment. Because of the role of methane emissions in radiative forcing of the atmosphere, the identification and quantification of sources of methane emissions is receiving increased scientific attention. Methane emission sources include biogenic, geogenic, and anthropogenic sources; the largest anthropogenic sources are natural gas and petroleum systems, enteric fermentation (livestock), landfills, coal mining, and manure management. While these source categories are well-known, there is significant uncertainty in the relative magnitudes of methane emissions from the various source categories. Further, the overall magnitude of methane emissions from all anthropogenic sources is actively debated, with estimates based on source sampling extrapolated to regional or national scale ("bottom-up analyses") differing from estimates that infer emissions based on ambient data ("top-down analyses") by 50% or more. To address the important problem of attribution of methane to specific sources, a variety of new analytical methods are being employed, including high time resolution and highly sensitive measurements of methane, methane isotopes, and other chemical species frequently associated with methane emissions, such as ethane. This Account describes the use of some of these emerging measurements, in both top-down and bottom-up methane emission studies. In addition, this Account describes how data from these new analytical methods can be used in conjunction with chemical mass balance (CMB) methods for source

  7. Attributing Atmospheric Methane to Anthropogenic Emission Sources.

    PubMed

    Allen, David

    2016-07-19

    Methane is a greenhouse gas, and increases in atmospheric methane concentration over the past 250 years have driven increased radiative forcing of the atmosphere. Increases in atmospheric methane concentration since 1750 account for approximately 17% of increases in radiative forcing of the atmosphere, and that percentage increases by approximately a factor of 2 if the effects of the greenhouse gases produced by the atmospheric reactions of methane are included in the assessment. Because of the role of methane emissions in radiative forcing of the atmosphere, the identification and quantification of sources of methane emissions is receiving increased scientific attention. Methane emission sources include biogenic, geogenic, and anthropogenic sources; the largest anthropogenic sources are natural gas and petroleum systems, enteric fermentation (livestock), landfills, coal mining, and manure management. While these source categories are well-known, there is significant uncertainty in the relative magnitudes of methane emissions from the various source categories. Further, the overall magnitude of methane emissions from all anthropogenic sources is actively debated, with estimates based on source sampling extrapolated to regional or national scale ("bottom-up analyses") differing from estimates that infer emissions based on ambient data ("top-down analyses") by 50% or more. To address the important problem of attribution of methane to specific sources, a variety of new analytical methods are being employed, including high time resolution and highly sensitive measurements of methane, methane isotopes, and other chemical species frequently associated with methane emissions, such as ethane. This Account describes the use of some of these emerging measurements, in both top-down and bottom-up methane emission studies. In addition, this Account describes how data from these new analytical methods can be used in conjunction with chemical mass balance (CMB) methods for source

  8. Abundance, distribution and potential activity of methane oxidizing bacteria in permafrost soils from the Lena Delta, Siberia.

    PubMed

    Liebner, Susanne; Wagner, Dirk

    2007-01-01

    The methane oxidation potential of active layer profiles of permafrost soils from the Lena Delta, Siberia, was studied with regard to its respond to temperature, and abundance and distribution of type I and type II methanotrophs. Our results indicate vertical shifts within the optimal methane oxidation temperature and within the distribution of type I and type II methanotrophs. In the upper active layer, maximum methane oxidation potentials were detected at 21 degrees C. Deep active layer zones that are constantly exposed to temperatures below 2 degrees C showed a maximum potential to oxidize methane at 4 degrees C. Our results indicate a dominance of psychrophilic methanotrophs close to the permafrost table. Type I methanotrophs dominated throughout the active layer profiles but their number strongly fluctuated with depth. In contrast, type II methanotrophs were constantly abundant through the whole active layer and displaced type I methanotrophs close to the permafrost table. No correlation between in situ temperatures and the distribution of type I and type II methanotrophs was found. However, the distribution of type I and type II methanotrophs correlated significantly with in situ methane concentrations. Beside vertical fluctuations, the abundance of methane oxidizers also fluctuated according to different geomorphic units. Similar methanotroph cell counts were detected in samples of a flood plain and a polygon rim, whereas cell counts in samples of a polygon centre were up to 100 times lower. PMID:17227416

  9. [Copper in methane oxidation: a review].

    PubMed

    Su, Yao; Kong, Jiao-Yan; Zhang, Xuan; Xia, Fang-Fang; He, Ruo

    2014-04-01

    Methane bio-oxidation plays an important role in the global methane balance and warming mitigation, while copper has a crucial function in methane bio-oxidation. On one side, copper is known to be a key factor in regulating the expression of the genes encoding the two forms of methane monooxygenases (MMOs) and is the essential metal element of the particulate methane monooxygenase (pMMO). On the other side, the content and fractionation of copper in the environment have great effects on the distribution of methanotrophs and their metabolic capability of methane and non-methane organic compounds, as well as on the copper-specific uptake systems in methanotrophs. Thus, it is meaningful to know the role of copper in methane bio-oxidation for comprehensive understanding of this process and is valuable for guiding the application of methanotrophs in greenhouse gas removal and pollution remediation. In this paper, the roles of copper in methane oxidation were reviewed, including the effect of copper on methanotrophic community structure and activity, the expression and activity of MMOs as well as the copper uptake systems in methanotrophs. The future studies of copper and methane oxidation were also discussed.

  10. Photocatalytic conversion of methane to methanol

    SciTech Connect

    Taylor, C.E.; Noceti, R.P.; D`Este, J.R.

    1995-12-31

    A long-term goal of our research group is the exploration of novel pathways for the direct oxidation of methane to liquid fuels, chemicals, and intermediates. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol is attractive. The products of reaction, methanol and hydrogen, are both commercially desirable, methanol being used as is or converted to a variety of other chemicals, and the hydrogen could be utilized in petroleum and/or chemical manufacturing. Methane is produced as a by-product of coal gasification. Depending upon reactor design and operating conditions, up to 18% of total gasifier product may be methane. In addition, there are vast proven reserves of geologic methane in the world. Unfortunately, a large fraction of these reserves are in regions where there is little local demand for methane and it is not economically feasible to transport it to a market. There is a global research effort under way in academia, industry, and government to find methods to convert methane to useful, more readily transportable and storable materials. Methanol, the initial product of methane oxidation, is a desirable product of conversion because it retains much of the original energy of the methane while satisfying transportation and storage requirements. Investigation of direct conversion of methane to transportation fuels has been an ongoing effort at PETC for over 10 years. One of the current areas of research is the conversion of methane to methanol, under mild conditions, using light, water, and a semiconductor photocatalyst. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol, is attractive. Research in the laboratory is directed toward applying the techniques developed for the photocatalytic splitting of the water and the photochemical conversion of methane.

  11. A molecular dynamics study on the transport of a charged biomolecule in a polymeric adsorbent medium and its adsorption onto a charged ligand.

    PubMed

    Riccardi, E; Wang, J-C; Liapis, A I

    2010-08-28

    The transport of a charged adsorbate biomolecule in a porous polymeric adsorbent medium and its adsorption onto the covalently immobilized ligands have been modeled and investigated using molecular dynamics modeling and simulations as the third part of a novel fundamental methodology developed for studying ion-exchange chromatography based bioseparations. To overcome computational challenges, a novel simulation approach is devised where appropriate atomistic and coarse grain models are employed simultaneously and the transport of the adsorbate is characterized through a number of locations representative of the progress of the transport process. The adsorbate biomolecule for the system studied in this work changes shape, orientation, and lateral position in order to proceed toward the site where adsorption occurs and exhibits decreased mass transport coefficients as it approaches closer to the immobilized ligand. Furthermore, because the ligands are surrounded by counterions carrying the same type of charge as the adsorbate biomolecule, it takes the biomolecule repeated attempts to approach toward a ligand in order to displace the counterions in the proximity of the ligand and to finally become adsorbed. The formed adsorbate-ligand complex interacts with the counterions and polymeric molecules and is found to evolve slowly and continuously from one-site (monovalent) interaction to multisite (multivalent) interactions. Such a transition of the nature of adsorption reduces the overall adsorption capacity of the ligands in the adsorbent medium and results in a type of surface exclusion effect. Also, the adsorption of the biomolecule also presents certain volume exclusion effects by not only directly reducing the pore volume and the availability of the ligands in the adjacent regions, but also causing the polymeric molecules to change to more compact structures that could further shield certain ligands from being accessible to subsequent adsorbate molecules. These

  12. A molecular dynamics study on the transport of a charged biomolecule in a polymeric adsorbent medium and its adsorption onto a charged ligand

    NASA Astrophysics Data System (ADS)

    Riccardi, E.; Wang, J.-C.; Liapis, A. I.

    2010-08-01

    The transport of a charged adsorbate biomolecule in a porous polymeric adsorbent medium and its adsorption onto the covalently immobilized ligands have been modeled and investigated using molecular dynamics modeling and simulations as the third part of a novel fundamental methodology developed for studying ion-exchange chromatography based bioseparations. To overcome computational challenges, a novel simulation approach is devised where appropriate atomistic and coarse grain models are employed simultaneously and the transport of the adsorbate is characterized through a number of locations representative of the progress of the transport process. The adsorbate biomolecule for the system studied in this work changes shape, orientation, and lateral position in order to proceed toward the site where adsorption occurs and exhibits decreased mass transport coefficients as it approaches closer to the immobilized ligand. Furthermore, because the ligands are surrounded by counterions carrying the same type of charge as the adsorbate biomolecule, it takes the biomolecule repeated attempts to approach toward a ligand in order to displace the counterions in the proximity of the ligand and to finally become adsorbed. The formed adsorbate-ligand complex interacts with the counterions and polymeric molecules and is found to evolve slowly and continuously from one-site (monovalent) interaction to multisite (multivalent) interactions. Such a transition of the nature of adsorption reduces the overall adsorption capacity of the ligands in the adsorbent medium and results in a type of surface exclusion effect. Also, the adsorption of the biomolecule also presents certain volume exclusion effects by not only directly reducing the pore volume and the availability of the ligands in the adjacent regions, but also causing the polymeric molecules to change to more compact structures that could further shield certain ligands from being accessible to subsequent adsorbate molecules. These

  13. Removal of caffeine from pharmaceutical wastewater by adsorption: influence of NOM, textural and chemical properties of the adsorbent.

    PubMed

    Álvarez-Torrellas, Silvia; Rodríguez, Araceli; Ovejero, Gabriel; Gómez, José María; García, Juan

    2016-01-01

    This work involves the study of the influence of textural and chemical adsorbent properties on natural organic matter (NOM) removal and the simultaneous adsorption of caffeine and NOM in pharmaceutical wastewater. The performance of a microporous activated carbon, Calgon F400, a synthesized mesoporous carbon from peach stones and a commercial sepiolite in the removal of NOM of a WWTP effluent, and the competitive adsorption of caffeine/NOM were evaluated. It was evidenced that the microporous structure of the adsorbents significantly conditioned the removal of NOM, finding that F400 activated carbon (microporous volume of 0.46 cm(3) g(-1)) led to a NOM removal of 45%. The presence of NOM in the aqueous medium led to worse adsorption parameters, including adsorption capacity at breakthrough time, mass transfer zone length and fractional bed utilization. Additionally, an overshooting in the Total Organic Carbon concentration (TOC/TOC0 = 1.05) was observed in the sepiolite adsorption fixed-bed experiment, due to the displacement of the background NOM. The tested adsorbents were efficient in the removal of caffeine from a pharmaceutical wastewater, finding a competitive effect between the target compound and the background NOM for the active sites. PMID:26593681

  14. Removal of caffeine from pharmaceutical wastewater by adsorption: influence of NOM, textural and chemical properties of the adsorbent.

    PubMed

    Álvarez-Torrellas, Silvia; Rodríguez, Araceli; Ovejero, Gabriel; Gómez, José María; García, Juan

    2016-01-01

    This work involves the study of the influence of textural and chemical adsorbent properties on natural organic matter (NOM) removal and the simultaneous adsorption of caffeine and NOM in pharmaceutical wastewater. The performance of a microporous activated carbon, Calgon F400, a synthesized mesoporous carbon from peach stones and a commercial sepiolite in the removal of NOM of a WWTP effluent, and the competitive adsorption of caffeine/NOM were evaluated. It was evidenced that the microporous structure of the adsorbents significantly conditioned the removal of NOM, finding that F400 activated carbon (microporous volume of 0.46 cm(3) g(-1)) led to a NOM removal of 45%. The presence of NOM in the aqueous medium led to worse adsorption parameters, including adsorption capacity at breakthrough time, mass transfer zone length and fractional bed utilization. Additionally, an overshooting in the Total Organic Carbon concentration (TOC/TOC0 = 1.05) was observed in the sepiolite adsorption fixed-bed experiment, due to the displacement of the background NOM. The tested adsorbents were efficient in the removal of caffeine from a pharmaceutical wastewater, finding a competitive effect between the target compound and the background NOM for the active sites.

  15. Global surface displacement data for assessing variability of displacement at a point on a fault

    USGS Publications Warehouse

    Hecker, Suzanne; Sickler, Robert; Feigelson, Leah; Abrahamson, Norman; Hassett, Will; Rosa, Carla; Sanquini, Ann

    2014-01-01

    This report presents a global dataset of site-specific surface-displacement data on faults. We have compiled estimates of successive displacements attributed to individual earthquakes, mainly paleoearthquakes, at sites where two or more events have been documented, as a basis for analyzing inter-event variability in surface displacement on continental faults. An earlier version of this composite dataset was used in a recent study relating the variability of surface displacement at a point to the magnitude-frequency distribution of earthquakes on faults, and to hazard from fault rupture (Hecker and others, 2013). The purpose of this follow-on report is to provide potential data users with an updated comprehensive dataset, largely complete through 2010 for studies in English-language publications, as well as in some unpublished reports and abstract volumes.

  16. Pluto: evidence for methane frost.

    PubMed

    1976-11-19

    Infrared photometry (1.2 to 2.2 micrometers) of Pluto provides evidence for frozen methane on the surface of the planet. This appears to be the first observational indication of this ice in the solar system. Its presence on Pluto suggests that the planet's albedo (reflectance) may be >/= 0.4 and that its diameter may be less than that of the moon.

  17. Radiation grafted adsorbents for newly emerging environmental applications

    NASA Astrophysics Data System (ADS)

    Mahmoud Nasef, Mohamed; Ting, T. M.; Abbasi, Ali; Layeghi-moghaddam, Alireza; Sara Alinezhad, S.; Hashim, Kamaruddin

    2016-01-01

    Radiation induced grafting (RIG) is acquired to prepare a number of adsorbents for newly emerging environmental applications using a single route involving RIG of glycidymethacrylate (GMA) onto polyethylene-polypropylene (PE-PP) non-woven fabric. The grafted fabric was subjected to one of three functionalization reactions to impart desired ionic characters. This included treatment with (1) N-dimethyl-D-glucamine, (2) triethylamine and (3) triethylamine and alkalisation with KOH. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) were used to study the changes in chemical and physical structures of the obtained fibrous adsorbents. The potential applications of the three adsorbents for removal of boron from solutions, capturing CO2 from CO2/N2 mixtures and catalysing transesterification of triacetin/methanol to methyl acetate (biodiesel) were explored. The obtained fibrous adsorbents provide potential alternatives to granular resins for the investigated applications and require further development.

  18. Adsorption of β-galactosidase on silica and aluminosilicate adsorbents

    NASA Astrophysics Data System (ADS)

    Atyaksheva, L. F.; Dobryakova, I. V.; Pilipenko, O. S.

    2015-03-01

    It is shown that adsorption of β-galactosidase of Aspergillus oryzae fungi on mesoporous and biporous silica and aluminosilicate adsorbents and the rate of the process grow along with the diameter of the pores of the adsorbent. It is found that the shape of the adsorption isotherms changes as well, depending on the texture of the adsorbent: the Michaelis constant rises from 0.3 mM for the enzyme in solution to 0.4-0.5 mM for the enzyme on a surface in the hydrolysis of o-nitrophenyl-β-D-galactopyranoside. It is concluded that β-galactosidase displays its maximum activity on the surface of biporous adsorbents.

  19. Mycotoxin detoxication of animal feed by different adsorbents.

    PubMed

    Huwig, A; Freimund, S; Käppeli, O; Dutler, H

    2001-06-20

    The contamination of animal feed with mycotoxins represents a worldwide problem for farmers. These toxins originate from molds whose growth on living and stored plants is almost unavoidable particularly under moist conditions. Mycotoxin-containing feed can cause serious diseases in farm animals resulting in suffering and even death and thus can cause substantial economic losses. The most applied method for protecting animals against mycotoxicosis is the utilization of adsorbents mixed with the feed which are supposed to bind the mycotoxins efficiently in the gastro-intestinal tract. Aluminosilicates are the preferred adsorbents, followed by activated charcoal and special polymers. The efficiency of mycotoxin binders, however, differs considerably depending mainly on the chemical structure of both the adsorbent and the toxin. This review describes the most important types of adsorbents and the respective mechanisms of adsorption. Data of the in vitro and in vivo efficacy of detoxication are given.

  20. New insights into perfluorinated adsorbents for analytical and bioanalytical applications.

    PubMed

    Marchetti, Nicola; Guzzinati, Roberta; Catani, Martina; Massi, Alessandro; Pasti, Luisa; Cavazzini, Alberto

    2015-01-01

    Perfluorinated (F-) adsorbents are generally prepared by bonding perfluoro-functionalized silanes to silica gels. They have been employed for a long time essentially as media for solid-phase extraction of F-molecules or F-tagged molecules in organic chemistry and heterogeneous catalysis. More recently, this approach has been extended to proteomics and metabolomics. Owing to their unique physicochemical properties, namely fluorophilicity and proteinophilicity, and a better understanding of some fundamental aspects of their behavior, new applications of F-adsorbents in the field of environmental science and bio-affinity studies can be envisaged. In this article, we revisit the most important features of F-adsorbents by focusing, in particular, on some basic information that has been recently obtained through (nonlinear) chromatographic studies. Finally, we try to envisage new applications and possibilities that F-adsorbents will allow in the near future. PMID:25358910

  1. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    SciTech Connect

    Weinelt, M.; Nilsson, A.; Wassdahl, N.

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  2. Adsorption of Pure Methane, Nitrogen, and Carbon Dioxide and Their Mixtures on San Juan Basin Coal

    SciTech Connect

    K. A. M. Gasem; R. L. Robinson; S. R. Reeves

    2002-03-01

    The major objectives of this project were to (a) measure the adsorption behavior of pure methane, nitrogen, CO{sub 2} and their binary and ternary mixtures on wet Tiffany coal at 130 F and pressures to 2000 psia; (b) correlate the equilibrium adsorption isotherm data using the extended Langmuir model, the Langmuir model, the loading ratio correlation and the Zhou-Gasem-Robinson equation of state; and (c) establish sorption-time estimates for the pure components. Specific accomplishments are summarized below regarding the complementary tasks involving experimental work and data correlation. Representative coal samples from BP Amoco Tiffany Injection Wells No.1 and No.10 were prepared, as requested. The equilibrium moisture content and particle size distribution of each coal sample were determined. Compositional coal analyses for both samples were performed by Huffman Laboratories, Inc. Pure gas adsorption for methane on wet Tiffany coal samples from Injection Wells No.1 and No.10 was measured separately at 130 F (327.6 K) and pressures to 2000 psia (13.7 MPa). The average expected uncertainty in these data is about 3% (9 SCF/ton). Our measurements indicate that the adsorption isotherms of the two coal samples exhibit similar Langmuir-type behavior. For the samples from the two wells, a maximum variation of about 5% in the amount adsorbed is observed at 2000 psia. Gas adsorption isotherms were measured for pure methane, nitrogen and CO{sub 2} on a wet, mixed Tiffany coal sample. The coal sample was an equal-mass mixture of coals from Well No.1 and Well No.10. The adsorption measurements were conducted at 130 F at pressures to 2000 psia. The adsorption isotherms have average expected experimental uncertainties of 3% (9 SCF/ton), 6% (8 SCF/ton), and 7% (62 SCF/ton) for methane, nitrogen, and CO{sub 2}, respectively. Adsorption isotherms were measured for methane/nitrogen, methane/CO{sub 2} and nitrogen/CO{sub 2} binary mixtures on wet, mixed Tiffany coal at 130 F and

  3. Oil palm biomass as an adsorbent for heavy metals.

    PubMed

    Vakili, Mohammadtaghi; Rafatullah, Mohd; Ibrahim, Mahamad Hakimi; Abdullah, Ahmad Zuhairi; Salamatinia, Babak; Gholami, Zahra

    2014-01-01

    Many industries discharge untreated wastewater into the environment. Heavy metals from many industrial processes end up as hazardous pollutants of wastewaters.Heavy metal pollution has increased in recent decades and there is a growing concern for the public health risk they may pose. To remove heavy metal ions from polluted waste streams, adsorption processes are among the most common and effective treatment methods. The adsorbents that are used to remove heavy metal ions from aqueous media have both advantages and disadvantages. Cost and effectiveness are two of the most prominent criteria for choosing adsorbents. Because cost is so important, great effort has been extended to study and find effective lower cost adsorbents.One class of adsorbents that is gaining considerable attention is agricultural wastes. Among many alternatives, palm oil biomasses have shown promise as effective adsorbents for removing heavy metals from wastewater. The palm oil industry has rapidly expanded in recent years, and a large amount of palm oil biomass is available. This biomass is a low-cost agricultural waste that exhibits, either in its raw form or after being processed, the potential for eliminating heavy metal ions from wastewater. In this article, we provide background information on oil palm biomass and describe studies that indicate its potential as an alternative adsorbent for removing heavy metal ions from wastewater. From having reviewed the cogent literature on this topic we are encouraged that low-cost oil-palm-related adsorbents have already demonstrated outstanding removal capabilities for various pollutants.Because cost is so important to those who choose to clean waste streams by using adsorbents, the use of cheap sources of unconventional adsorbents is increasingly being investigated. An adsorbent is considered to be inexpensive when it is readily available, is environmentally friendly, is cost-effective and be effectively used in economical processes. The

  4. Oil palm biomass as an adsorbent for heavy metals.

    PubMed

    Vakili, Mohammadtaghi; Rafatullah, Mohd; Ibrahim, Mahamad Hakimi; Abdullah, Ahmad Zuhairi; Salamatinia, Babak; Gholami, Zahra

    2014-01-01

    Many industries discharge untreated wastewater into the environment. Heavy metals from many industrial processes end up as hazardous pollutants of wastewaters.Heavy metal pollution has increased in recent decades and there is a growing concern for the public health risk they may pose. To remove heavy metal ions from polluted waste streams, adsorption processes are among the most common and effective treatment methods. The adsorbents that are used to remove heavy metal ions from aqueous media have both advantages and disadvantages. Cost and effectiveness are two of the most prominent criteria for choosing adsorbents. Because cost is so important, great effort has been extended to study and find effective lower cost adsorbents.One class of adsorbents that is gaining considerable attention is agricultural wastes. Among many alternatives, palm oil biomasses have shown promise as effective adsorbents for removing heavy metals from wastewater. The palm oil industry has rapidly expanded in recent years, and a large amount of palm oil biomass is available. This biomass is a low-cost agricultural waste that exhibits, either in its raw form or after being processed, the potential for eliminating heavy metal ions from wastewater. In this article, we provide background information on oil palm biomass and describe studies that indicate its potential as an alternative adsorbent for removing heavy metal ions from wastewater. From having reviewed the cogent literature on this topic we are encouraged that low-cost oil-palm-related adsorbents have already demonstrated outstanding removal capabilities for various pollutants.Because cost is so important to those who choose to clean waste streams by using adsorbents, the use of cheap sources of unconventional adsorbents is increasingly being investigated. An adsorbent is considered to be inexpensive when it is readily available, is environmentally friendly, is cost-effective and be effectively used in economical processes. The

  5. Titan's Methane Cycle is Closed

    NASA Astrophysics Data System (ADS)

    Hofgartner, J. D.; Lunine, J. I.

    2013-12-01

    Doppler tracking of the Cassini spacecraft determined a polar moment of inertia for Titan of 0.34 (Iess et al., 2010, Science, 327, 1367). Assuming hydrostatic equilibrium, one interpretation is that Titan's silicate core is partially hydrated (Castillo-Rogez and Lunine, 2010, Geophys. Res. Lett., 37, L20205). These authors point out that for the core to have avoided complete thermal dehydration to the present day, at least 30% of the potassium content of Titan must have leached into an overlying water ocean by the end of the core overturn. We calculate that for probable ammonia compositions of Titan's ocean (compositions with greater than 1% ammonia by weight), that this amount of potassium leaching is achievable via the substitution of ammonium for potassium during the hydration epoch. Formation of a hydrous core early in Titan's history by serpentinization results in the loss of one hydrogen molecule for every hydrating water molecule. We calculate that complete serpentinization of Titan's core corresponds to the release of more than enough hydrogen to reconstitute all of the methane atoms photolyzed throughout Titan's history. Insertion of molecular hydrogen by double occupancy into crustal clathrates provides a storage medium and an opportunity for ethane to be converted back to methane slowly over time--potentially completing a cycle that extends the lifetime of methane in Titan's surface atmosphere system by factors of several to an order of magnitude over the photochemically-calculated lifetime.

  6. Ceramic membranes for methane conversion

    SciTech Connect

    Balachandran, U.; Dusek, J.T.; Mieville, R.L.; Maiya, P.S.; Kleefisch, M.S.; Pei, S.; Kobylinski, T.P.; Udovich, C.A.

    1994-09-01

    In conventional conversion of methane to syngas, a significant cost of the partial oxidation process is that of the oxygen plant. In this report, the authors offer a technology that is based on dense ceramic membranes and that uses air as the oxidant for methane-conversion reactions, thus eliminating the need for the oxygen plant. Certain ceramic materials exhibit both electronic and ionic conductivities (of particular interest is oxygen-ion conductivity). These materials transport not only oxygen ions (functioning as selective oxygen separators) but also electrons back from the reactor side to the oxygen/reduction interface. No external electrodes are required and if the driving potential of transport is sufficient, the partial-oxidation reactions should be spontaneous. Such a system will operate without an externally applied potential. Oxygen is transported across the ceramic material in the form of oxygen anions, not oxygen molecules. Long tubes of Sr-Fe-Co-O (SFC) membrane were fabricated by plastic extrusion, and thermal stability of the tubes was studied as a function of oxygen partial pressure and high-temperature XRD. Mechanical properties were measured and found to be acceptable for a reactor material. Fracture of certain SFC tubes was the consequence of an oxygen gradient that introduced a volumetric lattice difference between the inner and outer walls. However, tubes made with a particular stoichiometry (SFC-2) provided methane conversion efficiencies of >99% in a reactor and some of these tubes have operated for up to {approx}1,000 h.

  7. Residence time determination for adsorbent beds of different configurations

    SciTech Connect

    Otermat, J.E.; Wikoff, W.O.; Kovach, J.L.

    1995-02-01

    The residence time calculations of ASME AG-1 Code, Section FC, currently specify a screen surface area method, that is technically incorrect. Test data has been obtained on Type II adsorber trays of different configurations to establish residence time in the adsorber trays. These data indicate that the air volume/carbon volume ratio or the average screen area are more appropriate for the calculation of the residence time calculation than the currently used, smallest screen area basis.

  8. Character displacement of Cercopithecini primate visual signals

    PubMed Central

    Allen, William L.; Stevens, Martin; Higham, James P.

    2014-01-01

    Animal visual signals have the potential to act as an isolating barrier to prevent interbreeding of populations through a role in species recognition. Within communities of competing species, species recognition signals are predicted to undergo character displacement, becoming more visually distinctive from each other, however this pattern has rarely been identified. Using computational face recognition algorithms to model primate face processing, we demonstrate that the face patterns of guenons (tribe: Cercopithecini) have evolved under selection to become more visually distinctive from those of other guenon species with whom they are sympatric. The relationship between the appearances of sympatric species suggests that distinguishing conspecifics from other guenon species has been a major driver of diversification in guenon face appearance. Visual signals that have undergone character displacement may have had an important role in the tribe’s radiation, keeping populations that became geographically separated reproductively isolated on secondary contact. PMID:24967517

  9. Comparing anisotropic displacement parameters in protein structures.

    PubMed

    Merritt, E A

    1999-12-01

    The increasingly widespread use of synchrotron-radiation sources and cryo-preparation of samples in macromolecular crystallography has led to a dramatic increase in the number of macromolecular structures determined at atomic or near-atomic resolution. This permits expansion of the structural model to include anisotropic displacement parameters U(ij) for individual atoms. In order to explore the physical significance of these parameters in protein structures, it is useful to be able to compare quantitatively the electron-density distribution described by the refined U(ij) values associated with corresponding crystallographically independent atoms. This paper presents the derivation of an easily calculated correlation coefficient in real space between two atoms modeled with anisotropic displacement parameters. This measure is used to investigate the degree of similarity between chemically equivalent but crystallographically independent atoms in the set of protein structural models currently available from the Protein Data Bank.

  10. Charge-displacement analysis for excited states

    SciTech Connect

    Ronca, Enrico Tarantelli, Francesco; Pastore, Mariachiara Belpassi, Leonardo; De Angelis, Filippo; Angeli, Celestino; Cimiraglia, Renzo

    2014-02-07

    We extend the Charge-Displacement (CD) analysis, already successfully employed to describe the nature of intermolecular interactions [L. Belpassi et al., J. Am. Chem. Soc. 132, 13046 (2010)] and various types of controversial chemical bonds [L. Belpassi et al., J. Am. Chem. Soc. 130, 1048 (2008); N. Salvi et al., Chem. Eur. J. 16, 7231 (2010)], to study the charge fluxes accompanying electron excitations, and in particular the all-important charge-transfer (CT) phenomena. We demonstrate the usefulness of the new approach through applications to exemplary excitations in a series of molecules, encompassing various typical situations from valence, to Rydberg, to CT excitations. The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.

  11. Charge-displacement analysis for excited states

    NASA Astrophysics Data System (ADS)

    Ronca, Enrico; Pastore, Mariachiara; Belpassi, Leonardo; De Angelis, Filippo; Angeli, Celestino; Cimiraglia, Renzo; Tarantelli, Francesco

    2014-02-01

    We extend the Charge-Displacement (CD) analysis, already successfully employed to describe the nature of intermolecular interactions [L. Belpassi et al., J. Am. Chem. Soc. 132, 13046 (2010)] and various types of controversial chemical bonds [L. Belpassi et al., J. Am. Chem. Soc. 130, 1048 (2008); N. Salvi et al., Chem. Eur. J. 16, 7231 (2010)], to study the charge fluxes accompanying electron excitations, and in particular the all-important charge-transfer (CT) phenomena. We demonstrate the usefulness of the new approach through applications to exemplary excitations in a series of molecules, encompassing various typical situations from valence, to Rydberg, to CT excitations. The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.

  12. Wireless Measurement of Rotation and Displacement Rate

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Taylor, Bryant D.

    2007-01-01

    A magnetic field response sensor is designed to measure displacement or rotation rate without a physical connection to a power source, microprocessor, data acquisition equipment, or electrical circuitry. The sensor works with the magnetic field response recorder, which was described in Magnetic-Field-Response Measurement-Acquisition System, NASA Tech Briefs, Vol. 30, No. 6 (June 2006), page 28. These sensors are wirelessly powered and interrogated, and the measurement acquisition system and sensors are extremely lightweight.The response recorder uses oscillating magnetic fields to power the sensors. Once powered, the sensors respond with their own magnetic field. For displacement/ rotation measurements, the response recorder uses the sensor s response amplitude, which is dependent on the distance from the antenna. The recorder s antenna orientation and position are kept fixed, and the sampling period is constant.

  13. Wirelessly Interrogated Position or Displacement Sensors

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Taylor, Bryant D.

    2007-01-01

    Two simple position or displacement sensors based on inductance-capacitance resonant circuits have been conceived. These sensors are both powered and interrogated without use of wires and without making contact with other objects. Instead, excitation and interrogation are accomplished by means of a magnetic-field-response recorder. Both of the present position or displacement sensors consist essentially of variable rectangular parallel-plate capacitors electrically connected in series with fixed inductors. Simple inductance-capacitance circuits of the type used in these sensors are inherently robust; their basic mode of operation does not depend on maintenance of specific environmental conditions. Hence, these sensors can be used under such harsh conditions as cryogenic temperatures, high pressures, and radioactivity.

  14. Emergency contraception among refugees and the displaced.

    PubMed

    Goodyear, L; McGinn, T

    1998-01-01

    In 1994, the international relief community began to recognize and address the reproductive health needs of refugees and displaced populations. A minimum initial service package of reproductive health services for refugees and the displaced, which includes emergency contraception (EC), was developed and recommended for use in refugee settings. This paper describes the experience of one international relief organization, the International Rescue Committee (IRC), in introducing EC into its worldwide reproductive health program. A recent IRC survey found that EC is available in 4 out of 14 settings where it provides reproductive health services. A case study from Tanzania demonstrates the modes of delivery, the demand for EC by women who have experienced sexual violence, and the community responses to this method of contraception. More information, education, and communication directed at refugee communities; more donor support for supplies; and institutional commitment to train staff are needed to expand refugee access to EC. PMID:9859638

  15. Computing Fault Displacements from Surface Deformations

    NASA Technical Reports Server (NTRS)

    Lyzenga, Gregory; Parker, Jay; Donnellan, Andrea; Panero, Wendy

    2006-01-01

    Simplex is a computer program that calculates locations and displacements of subterranean faults from data on Earth-surface deformations. The calculation involves inversion of a forward model (given a point source representing a fault, a forward model calculates the surface deformations) for displacements, and strains caused by a fault located in isotropic, elastic half-space. The inversion involves the use of nonlinear, multiparameter estimation techniques. The input surface-deformation data can be in multiple formats, with absolute or differential positioning. The input data can be derived from multiple sources, including interferometric synthetic-aperture radar, the Global Positioning System, and strain meters. Parameters can be constrained or free. Estimates can be calculated for single or multiple faults. Estimates of parameters are accompanied by reports of their covariances and uncertainties. Simplex has been tested extensively against forward models and against other means of inverting geodetic data and seismic observations. This work

  16. Emergency contraception among refugees and the displaced.

    PubMed

    Goodyear, L; McGinn, T

    1998-01-01

    In 1994, the international relief community began to recognize and address the reproductive health needs of refugees and displaced populations. A minimum initial service package of reproductive health services for refugees and the displaced, which includes emergency contraception (EC), was developed and recommended for use in refugee settings. This paper describes the experience of one international relief organization, the International Rescue Committee (IRC), in introducing EC into its worldwide reproductive health program. A recent IRC survey found that EC is available in 4 out of 14 settings where it provides reproductive health services. A case study from Tanzania demonstrates the modes of delivery, the demand for EC by women who have experienced sexual violence, and the community responses to this method of contraception. More information, education, and communication directed at refugee communities; more donor support for supplies; and institutional commitment to train staff are needed to expand refugee access to EC.

  17. Laser displacement meter application for milling diagnostics

    NASA Astrophysics Data System (ADS)

    Ryabov, Oleg; Mori, Kazuo; Kasashima, Nagayoshi

    1998-09-01

    This paper presents the application of a laser displacement meter for direct multi-purpose sensing of milling tool conditions. Using a laser displacement meter, a laser beam is projected onto the cutting tool and subsequently reflected. The intensity as well as the angle of the reflected beam are measured. The signals are interpreted for identification of tool geometry, tool whirling, or vibration. Signal processing and analysis depend on the application. A prototype system has been developed to demonstrate the feasibility of various applications, namely (1) tool setting evaluation, (2) in-process measurement of milling cutter geometry and detection of tool failure, (3) continuous monitoring of milling cutter deterioration, (4) detection and measurement of chatter in milling, (5) measurement of milling tool bending and (6) thermal expansion.

  18. Evidence for methane in Martian meteorites

    PubMed Central

    Blamey, Nigel J. F.; Parnell, John; McMahon, Sean; Mark, Darren F.; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R. M.; Banerjee, Neil R.; Flemming, Roberta L.

    2015-01-01

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity. PMID:26079798

  19. Evidence for methane in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Blamey, Nigel J. F.; Parnell, John; McMahon, Sean; Mark, Darren F.; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R. M.; Banerjee, Neil R.; Flemming, Roberta L.

    2015-06-01

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity.

  20. Evidence for methane in Martian meteorites.

    PubMed

    Blamey, Nigel J F; Parnell, John; McMahon, Sean; Mark, Darren F; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R M; Banerjee, Neil R; Flemming, Roberta L

    2015-01-01

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity. PMID:26079798

  1. Emerging topics in marine methane biogeochemistry.

    PubMed

    Valentine, David L

    2011-01-01

    Our knowledge of physical, chemical, geological and biological processes affecting methane in the ocean and in underlying sediments is expanding at a rapid pace. On first inspection, marine methane biogeochemistry appears simple: Methane distribution in sediment is set by the deposition pattern of organic material, and the balance of sources and sinks keeps its concentration low in most waters. However, recent research reveals that methane is affected by complex biogeochemical processes whose interactions are understood only at a superficial level. Such processes span the deep-subsurface, near subsurface, and ocean waters, and relate primarily to the production, consumption, and transport of methane. The purpose of this synthesis is to examine select processes within the framework of methane biogeochemistry, to formulate hypotheses on how they might operate and interact with one another, and to consider their controls. PMID:21329202

  2. Methane-induced haemolysis of human erythrocytes.

    PubMed Central

    Batliwala, H; Somasundaram, T; Uzgiris, E E; Makowski, L

    1995-01-01

    Human erythrocytes were exposed to high concentrations of methane and nitrogen through the application of elevated partial pressures of these gas molecules. Cell leakage (haemolysis) was measured for cells exposed to these gases under a wide range of experimental conditions. Application of methane produces haemolysis at pressures far below the hydrostatic pressures known to disrupt membrane or protein structure. The effects of changes in buffer, temperature, diffusion rate and detergents were studied. Methane acts co-operatively with detergents to produce haemolysis at much lower detergent concentration than is required in the absence of methane or in the presence of nitrogen. At sufficiently high concentrations of methane, all cells are haemolysed. Increased temperature enhances the effect. Methane produces 50% haemolysis at a concentration of about 0.33 M compared with about 7.5 M methanol required for the same degree of haemolysis. Images Figure 1 PMID:7733880

  3. Evidence for methane in Martian meteorites.

    PubMed

    Blamey, Nigel J F; Parnell, John; McMahon, Sean; Mark, Darren F; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R M; Banerjee, Neil R; Flemming, Roberta L

    2015-06-16

    The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity.

  4. Efforts to Consolidate Chalcogels with Adsorbed Iodine

    SciTech Connect

    Riley, Brian J.; Pierce, David A.; Chun, Jaehun

    2013-08-28

    This document discusses ongoing work with non-oxide aerogels, called chalcogels, that are under development at the Pacific Northwest National Laboratory as sorbents for gaseous iodine. Work was conducted in fiscal year 2012 to demonstrate the feasibility of converting Sn2S3 chalcogel without iodine into a glass. This current document summarizes the work conducted in fiscal year 2013 to assess the consolidation potential of non-oxide aerogels with adsorbed iodine. The Sn2S3 and Sb13.5Sn5S20 chalcogels were selected for study. The first step in the process for these experiments was to load them with iodine (I2). The I2 uptake was ~68 mass% for Sn2S3 and ~50 mass% for Sb13.5Sn5S20 chalcogels. X-ray diffraction (XRD) of both sets of sorbents showed that metal-iodide complexes were formed during adsorption, i.e., SnI4 for Sn2S3 and SbI3 for Sb13.5Sn5S20. Additionally, metal-sulfide-iodide complexes were formed, i.e., SnSI for Sn2S3 and SbSI for Sb13.5Sn5S20. No XRD evidence for unreacted iodine was found in any of these samples. Once the chalcogels had reached maximum adsorption, the consolidation potential was assessed. Here, the sorbents were heated for consolidation in vacuum-sealed quartz vessels. The Sb13.5Sn5S20 chalcogel was heated both (1) in a glassy carbon crucible within a fused quartz tube and (2) in a single-containment fused quartz tube. The Sn2S3 chalcogel was only heated in a single-containment fused quartz tube. In both cases with the single-containment fused quartz experiments, the material consolidated nicely. However, in both cases, there were small fractions of metal iodides not incorporated into the final product as well as fused quartz particles within the melt due to the sample attacking the quartz wall during the heat treatment. The Sb13.5Sn5S20 did not appear to attack the glassy carbon crucible so, for future experiments, it would be ideal to apply a coating, such as pyrolytic graphite, to the inner walls of the fused quartz vessel to prevent

  5. Displacement phenomena in lectin affinity chromatography.

    PubMed

    Cho, Wonryeon

    2015-10-01

    The work described here examines displacement phenomena that play a role in lectin affinity chromatography and their potential to impact reproducibility. This was achieved using Lycopersicon esculentum lectin (LEL), a lectin widely used in monitoring cancer. Four small identical LEL columns were coupled in series to form a single affinity chromatography system with the last in the series connected to an absorbance detector. The serial affinity column set (SACS) was then loaded with human plasma proteins. At the completion of loading, the column set was disassembled, the four columns were eluted individually, the captured proteins were trypsin digested, the peptides were deglycosylated with PNGase F, and the parent proteins were identified through mass spectral analyses. Significantly different sets of glycoproteins were selected by each column, some proteins appearing to be exclusively bound to the first column while others were bound further along in the series. Clearly, sample displacement chromatography (SDC) occurs. Glycoproteins were bound at different places in the column train, identifying the presence of glycoforms with different affinity on a single glycoprotein. It is not possible to see these phenomena in the single column mode of chromatography. Moreover, low abundance proteins were enriched, which facilitates detection. The great advantage of this method is that it differentiates between glycoproteins on the basis of their binding affinity. Displacement phenomena are concluded to be a significant component of the separation mechanism in heavily loaded lectin affinity chromatography columns. This further suggests that care must be exercised in sample loading of lectin columns to prevent analyte displacement with nonretained proteins. PMID:26348026

  6. Ultra-High-Frequency Capacitive Displacement Sensor

    NASA Technical Reports Server (NTRS)

    Vanzandt, Thomas R.; Kenny, Thomas W.; Kaiser, William J.

    1994-01-01

    Improved class of compact, high-resolution capacitive displacement sensors operates at excitation frequency of 915 MHz and measures about 7.5 by 4 by 2 centimeters. Contains commercially available 915-MHz oscillator and transmission-line resonator. Resonator contains stripline inductor in addition to variable capacitor. Ultrahigh excitation frequency offers advantages of resolution and frequency response. Not deleteriously affected by mechanical overdriving, or contact between electrodes.

  7. Cryogenic adsorber design in a helium refrigeration system

    NASA Astrophysics Data System (ADS)

    Hu, Zhongjun; Zhang, Ning; Li, Zhengyu; Li, Q.

    2012-06-01

    The cryogenic adsorber is specially designed to eliminate impurities in gaseous helium such as O2, and N2 which is normally difficult to remove, based on the reversible cryotrapping of impurities on an activated carbon bed. The coconut shell activated carbon is adopted because of its developed micropore structure and specific surface area. This activated carbon adsorption is mostly determined by the micropore structure, and the adsorption rate of impurities is inversely proportional to the square of the particle sizes. The active carbon absorber's maximum permissible flow velocity is 0.25 m/s. When the gas flow velocity increases, the adsorption diffusion rate of the adsorbent is reduced, because an increase in the magnitude of the velocity resulted in a reduced amount of heat transfer to a unit volume of impure gas. According to the numerical simulation of N2 adsorption dynamics, the appropriate void tower link speed and the saturated adsorption capacity are determined. Then the diameter and height of the adsorber are designed. The mass transfer length should be taken into account in the adsorber height design. The pressure decrease is also calculated. The important factors that influence the adsorber pressure decrease are the void tower speed, the adsorbed layer height, and the active carbon particle shape and size.

  8. Activity of lactoperoxidase when adsorbed on protein layers.

    PubMed

    Haberska, Karolina; Svensson, Olof; Shleev, Sergey; Lindh, Liselott; Arnebrant, Thomas; Ruzgas, Tautgirdas

    2008-09-15

    Lactoperoxidase (LPO) is an enzyme, which is used as an antimicrobial agent in a number of applications, e.g., food technology. In the majority of applications LPO is added to a homogeneous product phase or immobilised on product surface. In the latter case, however, the measurements of LPO activity are seldom reported. In this paper we have assessed LPO enzymatic activity on bare and protein modified gold surfaces by means of electrochemistry. It was found that LPO rapidly adsorbs to bare gold surfaces resulting in an amount of LPO adsorbed of 2.9mg/m(2). A lower amount of adsorbed LPO is obtained if the gold surface is exposed to bovine serum albumin, bovine or human mucin prior to LPO adsorption. The enzymatic activity of the adsorbed enzyme is in general preserved at the experimental conditions and varies only moderately when comparing bare gold and gold surface pretreated with the selected proteins. The measurement of LPO specific activity, however, indicate that it is about 1.5 times higher if LPO is adsorbed on gold surfaces containing a small amount of preadsorbed mucin in comparison to the LPO directly adsorbed on bare gold.

  9. Control of acid gases using a fluidized bed adsorber.

    PubMed

    Chiang, Bo-Chin; Wey, Ming-Yen; Yeh, Chia-Lin

    2003-08-01

    During incineration, secondary pollutants such as acid gases, organic compounds, heavy metals and particulates are generated. Among these pollutants, the acid gases, including sulfur oxides (SO(x)) and hydrogen chloride (HCl), can cause corrosion of the incinerator piping and can generate acid rain after being emitted to the atmosphere. To address this problem, the present study used a novel combination of air pollution control devices (APCDs), composed of a fluidized bed adsorber integrated with a fabric filter. The major objective of the work is to demonstrate the performance of a fluidized bed adsorber for removal of acid gases from flue gas of an incinerator. The adsorbents added in the fluidized bed adsorber were mainly granular activated carbon (AC; with or without chemical treatment) and with calcium oxide used as an additive. The advantages of a fluidized bed reactor for high mass transfer and high gas-solid contact can enhance the removal of acid gases when using a dry method. On the other hand, because the fluidized bed can filter particles, fine particles prior to and after passing through the fluidized bed adsorber were investigated. The competing adsorption on activated carbon between different characteristics of pollutants was also given preliminary discussion. The results indicate that the removal efficiencies of the investigated acid gases, SO(2) and HCl, are higher than 94 and 87%, respectively. Thus, a fluidized bed adsorber integrated with a fabric filter has the potential to replace conventional APCDs, even when there are other pollutants at the same time.

  10. Evaluation of a cesium adsorbent grafted with ammonium 12-molybdophosphate

    NASA Astrophysics Data System (ADS)

    Shibata, Takuya; Seko, Noriaki; Amada, Haruyo; Kasai, Noboru; Saiki, Seiichi; Hoshina, Hiroyuki; Ueki, Yuji

    2016-02-01

    A fibrous cesium (Cs) adsorbent was developed using radiation-induced graft polymerization with a cross-linked structure containing a highly stable adsorption ligand. The ligand, ammonium 12-molybdophosphate (AMP), was successfully introduced onto the fibrous polyethylene trunk material. The resulting Cs adsorbent contained 36% nonwoven fabric polyethylene (NFPE), 1% AMP, 2% triallyl isocyanurate (TAIC) and 61% glycidyl methacrylate (GMA). The adsorbent's Cs adsorption capacity was evaluated using batch and column tests. It was determined that the adsorbent could be used in a wide pH range. The amount of desorbed molybdenum, which can be used as an estimate for AMP stability on the Cs adsorbent, was minimized at the standard drinking water pH range of 5.8-8.6. Based from the inspection on the adherence of these results to the requirements set forth by the Food Sanitation Act by a third party organization, it can be concluded that the developed Cs adsorbent can be safely utilized for drinking water.

  11. Synthesis and CO₂ adsorption properties of molecularly imprinted adsorbents.

    PubMed

    Zhao, Yi; Shen, Yanmei; Bai, Lu; Hao, Rongjie; Dong, Liyan

    2012-02-01

    A series of molecularly imprinted adsorbents of CO(2) were developed by molecular self-assembly procedures, using ethanedioic acid, acrylamide, and ethylene glycol dimethacrylate as template, functional monomer, and cross-linker, respectively. Textural properties of these adsorbents were characterized by N(2) adsorption experiment, thermo-gravimetric analysis, and Fourier transform infrared spectroscopy. CO(2) adsorption capacities of adsorbents were investigated by thermo-gravimetric balance under 15% CO(2)/85% Ar atmosphere. Adsorption selectivity of CO(2) was studied by fixed-bed adsorption/desorption experiments. All the adsorbents displayed good thermal stability at 200 °C. Among them, MIP1b, with the higher amine content, exhibited the largest CO(2) capacity, which maintained steady after 50 adsorption-desorption cycles. Although MIP3 showed the highest specific surface, the CO(2) capacity was lower than that of MIP1b. CO(2) adsorption mechanism of molecularly imprinted adsorbents was determined to be physical sorption according to the adsorption enthalpies integrated from the DSC heatflow profiles. The calculated separation factors of CO(2) under 15% CO(2)/85% N(2) atmosphere were above 100 for all adsorbents.

  12. Simultaneous muscle force and displacement transducer

    NASA Technical Reports Server (NTRS)

    Feldstein, C.; Lewis, G. W.; Culler, V. H. (Inventor)

    1980-01-01

    A myocardial transducer for simultaneously measuring force and displacement within a very small area of myocardium is disclosed. The transducer comprised of an elongated body forked at one end to form an inverted Y shaped beam with each branch of the beam constituting a low compliant tine for penetrating the myocardium to a predetermined depth. Bonded to one of the low compliance tines is a small piezoresistive element for converting a force acting on the beam into an electrical signal. A third high compliant tine of the transducer, which measures displacement of the myocardium in a direction in line with the two low compliant tines, is of a length that just pierces the surface membrane. A small piezoresistive element is bonded to the third tine at its upper end where its bending is greatest. Displacement of the myocardium causes a deformation in curvature of the third tine, and the second small piezoresistive element bonded to the surface of its curved end converts its deformation into an electrical signal.

  13. Comparing Teaching Approaches About Maxwell's Displacement Current

    NASA Astrophysics Data System (ADS)

    Karam, Ricardo; Coimbra, Debora; Pietrocola, Maurício

    2014-08-01

    Due to its fundamental role for the consolidation of Maxwell's equations, the displacement current is one of the most important topics of any introductory course on electromagnetism. Moreover, this episode is widely used by historians and philosophers of science as a case study to investigate several issues (e.g. the theory-experiment relationship). Despite the consensus among physics educators concerning the relevance of the topic, there are many possible ways to interpret and justify the need for the displacement current term. With the goal of understanding the didactical transposition of this topic more deeply, we investigate three of its domains: (1) The historical development of Maxwell's reasoning; (2) Different approaches to justify the term insertion in physics textbooks; and (3) Four lectures devoted to introduce the topic in undergraduate level given by four different professors. By reflecting on the differences between these three domains, significant evidence for the knowledge transformation caused by the didactization of this episode is provided. The main purpose of this comparative analysis is to assist physics educators in developing an epistemological surveillance regarding the teaching and learning of the displacement current.

  14. International Monetary Fund and aid displacement.

    PubMed

    Stuckler, David; Basu, Sanjay; McKee, Martin

    2011-01-01

    Several recent papers find evidence that global health aid is being diverted to reserves, education, military, or other sectors, and is displacing government spending. This is suggested to occur because ministers of finance have competing, possibly corrupt, priorities and deprive the health sector of resources. Studies have found that development assistance for health routed to governments has a negative impact on health spending and that similar assistance routed to private nongovernmental organizations has a positive impact. An alternative hypothesis is that World Bank and IMF macro-economic policies, which specifically advise governments to divert aid to reserves to cope with aid volatility and keep government spending low, could be causing the displacement of health aid. This article evaluates whether aid displacement was greater when countries undertook a new borrowing program from the IMF between 1996 and 2006. As found in existing studies, for each $1 of development assistance for health, about $0.37 is added to the health system. However, evaluating IMF-borrowing versus non-IMF-borrowing countries reveals that non-borrowers add about $0.45 whereas borrowers add less than $0.01 to the health system. On average, health system spending grew at about half the speed when countries were exposed to the IMF than when they were not. It is important to take account of the political economy of global health finance when interpreting data on financial flows.

  15. Character displacement and the origins of diversity

    PubMed Central

    Pfennig, David W.; Pfennig, Karin S.

    2012-01-01

    In The Origin of Species, Darwin proposed his ‘principle of divergence of character’ (a process now termed ‘character displacement’) to explain how new species arise and why they differ from one other phenotypically. Darwin maintained that the origin of species, and the evolution of differences between them, is ultimately caused by divergent selection acting to minimize competitive interactions between initially similar individuals, populations, and species. Here, we examine the empirical support for the various claims that constitute Darwin’s principle, specifically that: (1) competition promotes divergent trait evolution; (2) the strength of competitively mediated divergent selection increases with increasing phenotypic similarity between competitors; (3) divergence can occur within species; and (4) competitively mediated divergence can trigger speciation. We also explore aspects that Darwin failed to consider. In particular, we describe how: (1) divergence can arise from selection acting to lessen reproductive interactions; (2) divergence is fueled by the intersection of character displacement and sexual selection; and (3) phenotypic plasticity may play a key role in promoting character displacement. Generally, character displacement is well supported empirically, and it remains a vital explanation for how new species arise and diversify. PMID:21043778

  16. Thermal properties of methane gas hydrates

    USGS Publications Warehouse

    Waite, William F.

    2007-01-01

    Gas hydrates are crystalline solids in which molecules of a “guest” species occupy and stabilize cages formed by water molecules. Similar to ice in appearance (fig. 1), gas hydrates are stable at high pressures and temperatures above freezing (0°C). Methane is the most common naturally occurring hydrate guest species. Methane hydrates, also called simply “gas hydrates,” are extremely concentrated stores of methane and are found in shallow permafrost and continental margin sediments worldwide. Brought to sea-level conditions, methane hydrate breaks down and releases up to 160 times its own volume in methane gas. The methane stored in gas hydrates is of interest and concern to policy makers as a potential alternative energy resource and as a potent greenhouse gas that could be released from sediments to the atmosphere and ocean during global warming. In continental margin settings, methane release from gas hydrates also is a potential geohazard and could cause submarine landslides that endanger offshore infrastructure. Gas hydrate stability is sensitive to temperature changes. To understand methane release from gas hydrate, the U.S. Geological Survey (USGS) conducted a laboratory investigation of pure methane hydrate thermal properties at conditions relevant to accumulations of naturally occurring methane hydrate. Prior to this work, thermal properties for gas hydrates generally were measured on analog systems such as ice and non-methane hydrates or at temperatures below freezing; these conditions limit direct comparisons to methane hydrates in marine and permafrost sediment. Three thermal properties, defined succinctly by Briaud and Chaouch (1997), are estimated from the experiments described here: - Thermal conductivity, λ: if λ is high, heat travels easily through the material. - Thermal diffusivity, κ: if κ is high, it takes little time for the temperature to rise in the material. - Specific heat, cp: if cp is high, it takes a great deal of heat to

  17. Carbon isotope fractionation during microbial methane oxidation

    NASA Astrophysics Data System (ADS)

    Barker, James F.; Fritz, Peter

    1981-09-01

    Methane, a common trace constituent of groundwaters, occasionally makes up more than 20% of the total carbon in groundwaters1,2. In aerobic environments CH4-rich waters can enable microbial food chain supporting a mixed culture of bacteria with methane oxidation as the primary energy source to develop3. Such processes may influence the isotopic composition of the residual methane and because 13C/12C analyses have been used to characterize the genesis of methanes found in different environments, an understanding of the magnitude of such effects is necessary. In addition, carbon dioxide produced by the methane-utilizing bacteria can be added to the inorganic carbon pool of affected groundwaters. We found carbon dioxide experimentally produced by methane-utilizing bacteria to be enriched in 12C by 5.0-29.6‰, relative to the residual methane. Where methane-bearing groundwaters discharged into aerobic environments microbial methane oxidation occurred, with the residual methane becoming progressively enriched in 13C. Various models have been proposed to explain the 13C/12C and 14C content of the dissolved inorganic carbon (DIC) of groundwaters in terms of additions or losses during flow in the subsurface4,5. The knowledge of both stable carbon isotope ratios in various pools and the magnitude of carbon isotope fractionation during various processes allows geochemists to use the 13C/12C ratio of the DIC along with water chemistry to estimate corrected 14C groundwater ages4,5. We show here that a knowledge of the carbon isotope fractionation between CH4 and CO2 during microbial methane-utilization could modify such models for application to groundwaters affected by microbial methane oxidation.

  18. Methane Pyrolysis and Disposing Off Resulting Carbon

    NASA Technical Reports Server (NTRS)

    Sharma, P. K.; Rapp, D.; Rahotgi, N. K.

    1999-01-01

    Sabatier/Electrolysis (S/E) is a leading process for producing methane and oxygen for application to Mars ISPP. One significant problem with this process is that it produces an excess of methane for combustion with the amount of oxygen that is produced. Therefore, one must discard roughly half of the methane to obtain the proper stoichiometric methane/oxygen mixture for ascent from Mars. This is wasteful of hydrogen, which must be brought from Earth and is difficult to transport to Mars and store on Mars. To reduced the problem of transporting hydrogen to Mars, the S/E process can be augmented by another process which reduces overall hydrogen requirement. Three conceptual approaches for doing this are (1) recover hydrogen from the excess methane produced by the S/E process, (2) convert the methane to a higher hydrocarbon or other organic with a lower H/C ratio than methane, and (3) use a separate process (such as zirconia or reverse water gas shift reaction) to produce additional oxygen, thus utilizing all the methane produced by the Sabatier process. We report our results here on recovering hydrogen from the excess methane using pyrolysis of methane. Pyrolysis has the advantage that it produces almost pure hydrogen, and any unreacted methane can pass through the S/E process reactor. It has the disadvantage that disposing of the carbon produced by pyrolysis presents difficulties. Hydrogen may be obtained from methane by pyrolysis in the temperature range 10000-12000C. The main reaction products are hydrogen and carbon, though very small amounts of higher hydrocarbons, including aromatic hydrocarbons are formed. The conversion efficiency is about 95% at 12000C. One needs to distinguish between thermodynamic equilibrium conversion and conversion limited by kinetics in a finite reactor.

  19. Evaluation of methane emissions from Taiwanese paddies.

    PubMed

    Liu, Chen-Wuing; Wu, Chung-Yi

    2004-10-15

    The main greenhouse gases are carbon dioxide, methane and nitrous oxide. Methane is the most important because the warming effect of methane is 21 times greater than that of carbon dioxide. Methane emitted from rice paddy fields is a major source of atmospheric methane. In this work, a methane emission model (MEM), which integrates climate change, plant growth and degradation of soil organic matter, was applied to estimate the emission of methane from rice paddy fields in Taiwan. The estimated results indicate that much methane is emitted during the effective tillering and booting stages in the first crop season and during the transplanting stage in the second crop season in a year. Sensitivity analysis reveals that the temperature is the most important parameter that governs the methane emission rate. The order of the strengths of the effects of the other parameters is soil pH, soil water depth (SWD) and soil organic matter content. The masses of methane emitted from rice paddy fields of Taiwan in the first and second crop seasons are 28,507 and 350,231 tons, respectively. The amount of methane emitted during the second crop season is 12.5 times higher than that emitted in the first crop season. With a 12% reduction in planted area during the second crop season, methane emission could be reduced by 21%. In addition, removal of rice straw left from the first crop season and increasing the depth of flooding to 25 cm are also strategies that could help reduce annual emission by up to 18%.

  20. Ebullitive methane emissions from oxygenated wetland streams.

    PubMed

    Crawford, John T; Stanley, Emily H; Spawn, Seth A; Finlay, Jacques C; Loken, Luke C; Striegl, Robert G

    2014-11-01

    Stream and river carbon dioxide emissions are an important component of the global carbon cycle. Methane emissions from streams could also contribute to regional or global greenhouse gas cycling, but there are relatively few data regarding stream and river methane emissions. Furthermore, the available data do not typically include the ebullitive (bubble-mediated) pathway, instead focusing on emission of dissolved methane by diffusion or convection. Here, we show the importance of ebullitive methane emissions from small streams in the regional greenhouse gas balance of a lake and wetland-dominated landscape in temperate North America and identify the origin of the methane emitted from these well-oxygenated streams. Stream methane flux densities from this landscape tended to exceed those of nearby wetland diffusive fluxes as well as average global wetland ebullitive fluxes. Total stream ebullitive methane flux at the regional scale (103 Mg C yr(-1) ; over 6400 km(2) ) was of the same magnitude as diffusive methane flux previously documented at the same scale. Organic-rich stream sediments had the highest rates of bubble release and higher enrichment of methane in bubbles, but glacial sand sediments also exhibited high bubble emissions relative to other studied environments. Our results from a database of groundwater chemistry support the hypothesis that methane in bubbles is produced in anoxic near-stream sediment porewaters, and not in deeper, oxygenated groundwaters. Methane interacts with other key elemental cycles such as nitrogen, oxygen, and sulfur, which has implications for ecosystem changes such as drought and increased nutrient loading. Our results support the contention that streams, particularly those draining wetland landscapes of the northern hemisphere, are an important component of the global methane cycle.