WorldWideScience

Sample records for gas phase contaminants

  1. Removal of volatile to semi-volatile organic contaminants from water using hollow fiber membrane contactors and catalytic destruction of the contaminants in the gas phase

    OpenAIRE

    Tarafder, Shamsul Abedin

    2007-01-01

    Abstract Chlorinated organic compounds and ether compounds are frequently found in groundwater and efficient treatment options are needed. In this study, the efficient transferal of the compounds from the water phase to the gas phase was studied followed by the catalytic treatment of the gas phase. For the removal of the organic contaminants from water, a microporous polypropylene hollow fiber membrane (HFM) module was operated under low strip gas flow to water flow ratios (_< 5:1). Rem...

  2. Photocatalytic oxidation of gas-phase BTEX-contaminated waste streams

    Energy Technology Data Exchange (ETDEWEB)

    Gratson, D A; Nimlos, M R; Wolfrum, E J

    1995-03-01

    Researchers at the National Renewable Energy Laboratory (NREL) have been exploring heterogeneous photocatalytic oxidation (PCO) as a remediation technology for air streams contaminated with benzene, toluene, ethyl-benzene, and xylenes (BTEX). This research is a continuation of work performed on chlorinated organics. The photocatalytic oxidation of BTEX has been studied in the aqueous phase, however, a study by Turchi et al. showed a more economical system would involve stripping organic contaminants from the aqueous phase and treating the resulting gas stream. Another recent study by Turchi et al. indicated that PCO is cost competitive with such remediation technologies as activated carbon adsorption and catalytic incineration for some types of contaminated air streams. In this work we have examined the photocatalytic oxidation of benzene using ozone (0{sub 3}) as an additional oxidant. We varied the residence time in the PCO reactor, the initial concentration of the organic pollutant, and the initial ozone concentration in a single-pass reactor. Because aromatic hydrocarbons represent only a small fraction of the total hydrocarbons present in gasoline and other fuels, we also added octane to the reaction mixture to simulate the composition of air streams produced from soil-vapor-extraction or groundwater-stripping of sites contaminated with gasoline.

  3. Investigation of gas-phase decontamination of internally radioactively contaminated gaseous diffusion process equipment and piping

    International Nuclear Information System (INIS)

    Bundy, R.D.; Munday, E.B.

    1991-01-01

    Construction of the gaseous diffusion plants (GDPs) was begun during World War 2 to produce enriched uranium for defense purposes. These plants, which utilized UF 6 gas, were used primarily for this purpose through 1964. From 1959 through 1968, production shifted primarily to uranium enrichment to supply the nuclear power industry. Additional UF 6 -handling facilities were built in feed and fuel-processing plants associated with the uranium enrichment process. Two of the five process buildings at Oak ridge were shut down in 1964. Uranium enrichment activities at Oak Ridge were discontinued altogether in 1985. In 1987, the Department of Energy (DOE) decided to proceed with a permanent shutdown of the Oak Ridge Gaseous Diffusion Plant (ORGDP). DOE intends to begin decommissioning and decontamination (D ampersand D) of ORGDP early in the next century. The remaining two GDPs are expected to be shut down during the next 10 to 40 years and will also require D ampersand D, as will the other UF 6 -handling facilities. This paper presents an investigation of gas- phase decontamination of internally radioactively contaminated gaseous diffusion process equipment and piping using powerful fluorinating reagents that convert nonvolatile uranium compounds to volatile UF 6 . These reagents include ClF 3 , F 2 , and other compounds. The scope of D ampersand D at the GDPs, previous work of gas-phase decontamination, four concepts for using gas-phase decontamination, plans for further study of gas-phase decontamination, and the current status of this work are discussed. 13 refs., 15 figs

  4. A simulation model for the analysis of Space Station gas-phase trace contaminants

    Science.gov (United States)

    Brewer, Dana A.; Hall, John B., Jr.

    1987-01-01

    A simulation model for the analysis of gas-phase trace contaminants in the cabin air of the NASA Space Station Reference Configuration was developed at the NASA Langley Research Center. The model predicts changes in trace contaminant concentrations from both physical and chemical sources and sinks as a function of time. Simulations were performed in which values for relative humidity, temperature, radiation intensity, pressure, and initial species concentrations were constrained to values for these parameters measured and modeled in the continental tropics at the earth's surface. Species concentrations simulated using the model compared favorably with concentrations in the continental tropics which demonstrated that the chemical mechanism in the trace contaminant model approximates changes in atmospheric species concentrations. The sensitivity of initial species concentrations to producing changes in additional species concentrations was also assessed. Results from the model indicated that chemical reactions will be important in determining the composition of cabin air in the Space Station. It is anticipated that the trace contaminant model will be useful in assessing the impact of experiments and commercial operations on the composition of the cabin air in the Space Station.

  5. Modeled occupational exposures to gas-phase medical laser-generated air contaminants.

    Science.gov (United States)

    Lippert, Julia F; Lacey, Steven E; Jones, Rachael M

    2014-01-01

    Exposure monitoring data indicate the potential for substantive exposure to laser-generated air contaminants (LGAC); however the diversity of medical lasers and their applications limit generalization from direct workplace monitoring. Emission rates of seven previously reported gas-phase constituents of medical laser-generated air contaminants (LGAC) were determined experimentally and used in a semi-empirical two-zone model to estimate a range of plausible occupational exposures to health care staff. Single-source emission rates were generated in an emission chamber as a one-compartment mass balance model at steady-state. Clinical facility parameters such as room size and ventilation rate were based on standard ventilation and environmental conditions required for a laser surgical facility in compliance with regulatory agencies. All input variables in the model including point source emission rates were varied over an appropriate distribution in a Monte Carlo simulation to generate a range of time-weighted average (TWA) concentrations in the near and far field zones of the room in a conservative approach inclusive of all contributing factors to inform future predictive models. The concentrations were assessed for risk and the highest values were shown to be at least three orders of magnitude lower than the relevant occupational exposure limits (OELs). Estimated values do not appear to present a significant exposure hazard within the conditions of our emission rate estimates.

  6. Experimental evaluation of enthalpy efficiency and gas-phase contaminant transfer in an enthalpy recovery unit with polymer membrane foils

    DEFF Research Database (Denmark)

    Nie, Jinzhe; Yang, Jianrong; Fang, Lei

    2015-01-01

    Experimental studies were conducted in a laboratory setting to investigate the enthalpy efficiency and gas-phase contaminant transfer in a polymer membrane enthalpy recovery unit. One commercially available polymer membrane enthalpy recovery unit was used as a reference unit. Simulated indoor air...

  7. Triple sorbent thermal desorption/gas chromatography/mass spectrometry determination of vapor phase organic contaminants

    International Nuclear Information System (INIS)

    Ma, C.Y.; Skeen, J.T.; Dindal, A.B.; Higgins, C.E.; Jenkins, R.A.

    1994-05-01

    A thermal desorption/ps chromatography/mass spectrometry (TD/GC/MS) has been evaluated for the determination of volatile organic compounds (VOCS) in vapor phase samples using Carbosieve S-III/Carbotrap/Carotrap C triple sorbent traps (TST) similar to those available from a commercial source. The analysis was carried out with a Hewlett-Packard 5985A or 5995 GC/MS system with a modified injector to adapt an inhouse manufactured short-path desorber for transferring desorbate directly onto a cryofocusing loop for subsequent GC/MS analysis. Vapor phase standards generated from twenty six compounds were used for method validation, including alkanes, alkyl alcohols, alkyl ketones, and alkyl nitrites, a group of representative compounds that have previously been identified in a target airborne matrix. The method was validated based on the satisfactory results in terms of reproducibility, recovery rate, stability, and linearity. A relative, standard deviation of 0.55 to 24.3 % was obtained for the entire TD process (generation of gas phase standards, spiking the standards on and desorbing from TST) over a concentration range of 20 to 500 ng/trap. Linear correlation coefficients for the calibration curves as determined ranged from 0.81 to 0.99 and limits of detection ranged from 3 to 76 ng. For a majority of standards, recoveries of greater than 90% were observed. For three selected standards spiked on TSTS, minimal loss (10 to 22%) was observed after storing the spiked in, a 4 degree C refrigerator for 29 days. The only chromatographable artifact observed was a 5% conversion of isopropanol to acetone. The validated method been successfully applied, to the determination of VOCs collected from various emission sources in a diversified concentration range

  8. Triple sorbent thermal desorption/gas chromatography/mass spectrometry determination of vapor phase organic contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Ma, C.Y.; Skeen, J.T.; Dindal, A.B.; Higgins, C.E.; Jenkins, R.A.

    1994-05-01

    A thermal desorption/ps chromatography/mass spectrometry (TD/GC/MS) has been evaluated for the determination of volatile organic compounds (VOCS) in vapor phase samples using Carbosieve S-III/Carbotrap/Carotrap C triple sorbent traps (TST) similar to those available from a commercial source. The analysis was carried out with a Hewlett-Packard 5985A or 5995 GC/MS system with a modified injector to adapt an inhouse manufactured short-path desorber for transferring desorbate directly onto a cryofocusing loop for subsequent GC/MS analysis. Vapor phase standards generated from twenty six compounds were used for method validation, including alkanes, alkyl alcohols, alkyl ketones, and alkyl nitrites, a group of representative compounds that have previously been identified in a target airborne matrix. The method was validated based on the satisfactory results in terms of reproducibility, recovery rate, stability, and linearity. A relative, standard deviation of 0.55 to 24.3 % was obtained for the entire TD process (generation of gas phase standards, spiking the standards on and desorbing from TST) over a concentration range of 20 to 500 ng/trap. Linear correlation coefficients for the calibration curves as determined ranged from 0.81 to 0.99 and limits of detection ranged from 3 to 76 ng. For a majority of standards, recoveries of greater than 90% were observed. For three selected standards spiked on TSTS, minimal loss (10 to 22%) was observed after storing the spiked in, a 4{degree}C refrigerator for 29 days. The only chromatographable artifact observed was a 5% conversion of isopropanol to acetone. The validated method been successfully applied, to the determination of VOCs collected from various emission sources in a diversified concentration range.

  9. Organic Contaminants Associated with the Extraction of Unconventional Gas. Risk Analysis in the Initial Phases of the Project

    International Nuclear Information System (INIS)

    Xu, L.; Hurtado, A.; Recreo, F.; Eguilior, S.

    2015-01-01

    The latest technological advances in hydraulic fracturing and horizontal drilling are promoting a commercial scale extraction of unconventional fossil fuels in several regions of the world. Although there is still no commercial scale extraction in the Member States of the EU, potential stocks in some of them, as in the case of Spain, stimulate the need to carry out precautionary previous studies. These, based on the experience in the USA, will allow to define the characteristics that a priori should include a project of unconventional gas extraction, so that their safety is maximized by minimizing the likelihood of adverse effects on the environment. In unconventional gas production a fracturing fluid, typically water, with different types of additives is injected into the reservoir at very high pressure in order to create fractures to increase the porosity and permeability of the rock. In this scenario the flowback and produced water (water brought to the surface during the extraction of gas or oil) is usually a mixture of fluids injected and brines present in the repository. The quality of the flowback and produced water is variable. Its salinity varies from similar to drinking water to several times more saline than seawater. Furthermore, different compounds other than salt can be present in various amounts in the flowback and produced water: oil and other organic compounds, solids in suspension, bacteria, naturally occurring radioactive elements (NORM), and any of the elements injected with the hydraulic fracturing fluid. Due to the high variability of contaminants in the flowback and produced water as well as potentially large volumes involved, composition of flowback and produced water and the analysis of the risks associated with them is an important aspect to consider from the initial phases of project development of unconventional gas extraction. This report covers the risk analysis of an unconventional gas extraction project, the initial assessment of the

  10. Gas phase ion chemistry

    CERN Document Server

    Bowers, Michael T

    1979-01-01

    Gas Phase Ion Chemistry, Volume 2 covers the advances in gas phase ion chemistry. The book discusses the stabilities of positive ions from equilibrium gas-phase basicity measurements; the experimental methods used to determine molecular electron affinities, specifically photoelectron spectroscopy, photodetachment spectroscopy, charge transfer, and collisional ionization; and the gas-phase acidity scale. The text also describes the basis of the technique of chemical ionization mass spectrometry; the energetics and mechanisms of unimolecular reactions of positive ions; and the photodissociation

  11. Gas phase ion chemistry

    CERN Document Server

    Bowers, Michael T

    1979-01-01

    Gas Phase Ion Chemistry, Volume 1 covers papers on the advances of gas phase ion chemistry. The book discusses the advances in flow tubes and the measurement of ion-molecule rate coefficients and product distributions; the ion chemistry of the earth's atmosphere; and the classical ion-molecule collision theory. The text also describes statistical methods in reaction dynamics; the state selection by photoion-photoelectron coincidence; and the effects of temperature and pressure in the kinetics of ion-molecule reactions. The energy distribution in the unimolecular decomposition of ions, as well

  12. Gas-Phase Thermolyses

    DEFF Research Database (Denmark)

    Carlsen, Lars; Egsgaard, Helge

    1982-01-01

    The unimolecular gas-phase thermolyses of the four methyl and ethyl monothioacetates (5)–(8) have been studied by the flash vacuum thermolysis–field ionization mass spectrometry technique in the temperature range 883–1 404 K. The types of reactions verified were keten formation, thiono–thiolo rea......The unimolecular gas-phase thermolyses of the four methyl and ethyl monothioacetates (5)–(8) have been studied by the flash vacuum thermolysis–field ionization mass spectrometry technique in the temperature range 883–1 404 K. The types of reactions verified were keten formation, thiono...

  13. Gas phase pulse radiolysis

    International Nuclear Information System (INIS)

    Jonah, C.D.; Andong Liu; Mulac, W.A.

    1987-01-01

    Gas phase pulse radiolysis, a technique which can be used to study many different phenomena in chemistry and physics, is discussed. As a source of small radicals, pulse radiolysis is important to the field of chemistry, particularly to combustion and atmospheric kinetics. The reactions of 1,3-butadiene, allene, ethylene and acetylene with OH are presented. 52 refs., 1 fig., 1 tab

  14. Automated mini-column solid-phase extraction cleanup for high-throughput analysis of chemical contaminants in foods by low-pressure gas chromatography – tandem mass spectrometry

    Science.gov (United States)

    This study demonstrated the application of an automated high-throughput mini-cartridge solid-phase extraction (mini-SPE) cleanup for the rapid low-pressure gas chromatography – tandem mass spectrometry (LPGC-MS/MS) analysis of pesticides and environmental contaminants in QuEChERS extracts of foods. ...

  15. Degradation of gas-phase organic contaminants via nitrogen-embedded one-dimensional rod-shaped titania in a plug-flow reactor.

    Science.gov (United States)

    Jo, Wan-Kuen; Kang, Hyun-Jung; Chun, Ho-Hwan

    2014-01-01

    In this study, one-dimensional rod-shaped titania (RST) and nitrogen-doped RST (N-RST) with different ratios of N to Ti were prepared using a hydrothermal method and their applications for purification of indoor toxic organic contaminants in a plug-flow reactor were examined under visible or ultraviolet (UV) irradiation. The surface characteristics of as-prepared photocatalysts were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-visible spectroscopy. The TEM images revealed that both pure RSTs and N-RSTs displayed uniform and nanorod-shaped structures. XRD revealed that the photocatalysts had crystalline TiO2. The UV-visible spectra demonstrated that the N-RSTs could be activated in the visible region. In most cases, N-RSTs showed higher degradation efficiencies than pure RSTs under visible-light and UV irradiation. N-RSTs with a N-to-Ti ratio of 0.5 exhibited the highest degradation efficiencies of benzene, toluene, ethyl benzene, and o-xylene (BTEX), suggesting the presence of an optimal N-to-Ti ratio for preparation of N-RSTs. In addition, the average degradation efficiencies of BTEX determined for the N-RSTs with a N-to-Ti ratio of 0.5 under visible-light irradiation for the lowest initial concentration (IC, 0.1 ppm) were 19%, 53%, 85%, and 92%, respectively, while the degradation efficiencies for the highest IC (2.0 ppm) were 2%, 8%, 17%, and 33%. These values decreased as the stream flow rate increased. Overall, the as-prepared N-RSTs could be effectively applied for degradation of toxic gas-phase organic contaminants under visible-light as well as UV irradiation.

  16. Regenerable Contaminant Removal System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regenerable Contaminant Removal System (RCRS) is an innovative method to remove sulfur and halide compounds from contaminated gas streams to part-per-billion...

  17. Sticky windows: chemical and biological characteristics of the organic film derived from particulate and gas-phase air contaminants found on an urban impervious surface.

    Science.gov (United States)

    Hodge, E M; Diamond, M L; McCarry, B E; Stern, G A; Harper, P A

    2003-05-01

    A novel environmentally derived mixture that integrates exposure to atmospherically derived gas- and particle-phase compounds in urban areas-namely, the organic film that develops as a thin layer on urban impervious surfaces-was investigated for its ability to induce gene expression via the aryl hydrocarbon receptor (AhR). The organic film on window glass from 21 sites in downtown Toronto (Ontario, Canada) was found to contain a complex mixture of environmental contaminants typical of urban environments, notably PAHs, n-alkanes, PCBs, organochlorine (OC) pesticides, and polar constituents. Using a stably transfected reporter cell line, we found that the crude extract of organic film induces AhR-dependent gene expression in a dose-dependent fashion. Three subfractions of the crude extract induced significant luciferase expression: nonpolar aromatic > polar aromatic > nonpolar aliphatic. Recombination of the fractions did not lead to recovery of the full activity of the crude extract, which may indicate that some of the compounds lost during fractionation were significant contributors to the induction observed with the crude extract. The interactions between a tonic dose of B[ a]P (10(-7) M) and each of the aromatic fractions were determined to be antagonistic following analysis by the method of isoboles. Our results suggest that organic film makes up a diverse array of compounds active at the AhR and that these compounds may not interact in a strictly additive manner.

  18. Comparative evaluation of liquid-liquid extraction, solid-phase extraction and solid-phase microextraction for the gas chromatography-mass spectrometry determination of multiclass priority organic contaminants in wastewater.

    Science.gov (United States)

    Robles-Molina, José; Gilbert-López, Bienvenida; García-Reyes, Juan F; Molina-Díaz, Antonio

    2013-12-15

    The European Water Framework Directive (WFD) 2000/60/EC establishes guidelines to control the pollution of surface water by sorting out a list of priority substances that involves a significant risk to or via the aquatic systems. In this article, the analytical performance of three different sample preparation methodologies for the GC-MS/MS determination of multiclass organic contaminants-including priority comprounds from the WFD-in wastewater samples using gas chromatography-mass spectrometry was evaluated. The methodologies tested were: (a) liquid-liquid extraction (LLE) with n-hexane; (b) solid-phase extraction (SPE) with C18 cartridges and elution with ethyl acetate:dichloromethane (1:1 (v/v)), and (c) headspace solid-phase microextraction (HS-SPME) using two different fibers: polyacrylate and polydimethylsiloxane/carboxen/divinilbenzene. Identification and confirmation of the selected 57 compounds included in the study (comprising polycyclic aromatic hydrocarbons (PAHs), pesticides and other contaminants) were accomplished using gas chromatography tandem mass spectrometry (GC-MS/MS) with a triple quadrupole instrument operated in the multiple reaction monitoring (MRM) mode. Three MS/MS transitions were selected for unambiguous confirmation of the target chemicals. The different advantages and pitfalls of each method were discussed. In the case of both LLE and SPE procedures, the method was validated at two different concentration levels (15 and 150 ng L(-1)) obtaining recovery rates in the range 70-120% for most of the target compounds. In terms of analyte coverage, results with HS-SPME were not satisfactory, since 14 of the compounds tested were not properly recovered and the overall performance was worse than the other two methods tested. LLE, SPE and HS-SPME (using polyacrylate fiber) procedures also showed good linearity and precision. Using any of the three methodologies tested, limits of quantitation obtained for most of the detected compounds were in

  19. Gas-phase chemical dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Weston, R.E. Jr.; Sears, T.J.; Preses, J.M. [Brookhaven National Laboratory, Upton, NY (United States)

    1993-12-01

    Research in this program is directed towards the spectroscopy of small free radicals and reactive molecules and the state-to-state dynamics of gas phase collision, energy transfer, and photodissociation phenomena. Work on several systems is summarized here.

  20. Harvesting Hydrogen Gas from Air Pollutants with an Unbiased Gas Phase Photoelectrochemical Cell.

    Science.gov (United States)

    Verbruggen, Sammy W; Van Hal, Myrthe; Bosserez, Tom; Rongé, Jan; Hauchecorne, Birger; Martens, Johan A; Lenaerts, Silvia

    2017-04-10

    The concept of an all-gas-phase photoelectrochemical (PEC) cell producing hydrogen gas from volatile organic contaminated gas and light is presented. Without applying any external bias, organic contaminants are degraded and hydrogen gas is produced in separate electrode compartments. The system works most efficiently with organic pollutants in inert carrier gas. In the presence of oxygen, the cell performs less efficiently but still significant photocurrents are generated, showing the cell can be run on organic contaminated air. The purpose of this study is to demonstrate new application opportunities of PEC technology and to encourage further advancement toward PEC remediation of air pollution with the attractive feature of simultaneous energy recovery and pollution abatement. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Part-per-trillion determination of pharmaceuticals, pesticides, and related organic contaminants in river water by solid-phase extraction followed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry.

    Science.gov (United States)

    Matamoros, Víctor; Jover, Eric; Bayona, Josep M

    2010-01-15

    An analytical procedure based on comprehensive two-dimensional gas chromatography (GC x GC) coupled with time-of-flight mass spectrometry (TOF-MS) for the simultaneous determination of 97 organic contaminants at trace concentration in river water is presented. The target analytes included 13 pharmaceuticals, 18 plasticizers, 8 personal care products, 9 acid herbicides, 8 triazines, 10 organophosphorous compounds, 5 phenylureas, 12 organochlorine biocides, 9 polycyclic aromatic hydrocarbons (PAHs), and 5 benzothiazoles and benzotriazoles. The best resolution of the target analytes in the contour plots was obtained when a nonpolar stationary phase was used in the first dimension and polar one in the second. However, in the opposite configuration, polar-nonpolar, the retention time in the second dimension exhibited a strong correlation with the log Kow (p identification criteria. The developed methodology is based on a polymeric solid-phase extraction followed by in GC-port methylation and GC x GC/TOF-MS determination. Moreover, limits of detection (LODs) and quantification (LOQs) ranged from 0.5 to 100 ng/L and from 2 to 185 ng/L, respectively. Repeatability was always lower than 20%. Finally, the developed method has been successfully applied to the determination of incurred target analytes in four river waters subjected to a different anthropogenic pressure.

  2. Iodine removal from a gas phase

    International Nuclear Information System (INIS)

    Vikis, A. Ch.

    1982-01-01

    Iodine, e.g. radioactive iodine, present as one or more organic iodides, optionally with elemental iodine, in a gas phase (e.g. air) are removed by photochemically decomposing the organic iodides to elemental iodine, reacting the iodine produced, and any initially present with excess ozone, preferably photochemically produced in situ in the gas phase to produce solid iodine oxides, and removing the solid oxides from the gas phase. (author)

  3. Iodine removal from a gas phase

    International Nuclear Information System (INIS)

    Vikis, A.C.

    1984-01-01

    Iodine, e.g. radioactive iodine, present as one or more organic iodides, optionally with elemental iodine, in a gas phase (e.g. air) are removed by photochemically decomposing the organic iodides to elemental iodine, reacting the iodine produced, and any initially present with excess ozone, preferably photochemically produced in situ in the gas phase to produce solid iodine oxides, and removing the solid oxides from the gas phase

  4. A numerical investigation into factors affecting gas and aqueous phase plumes in the subsurface

    Science.gov (United States)

    Thomson, N. R.; Sykes, J. F.; Van Vliet, D.

    1997-10-01

    An investigation into the face and transport of volatile organic compounds (VOCs) in the subsurface requires the consideration of contaminant mass in both the aqueous and soil gas phases. As a result of water/gas phase partitioning, contaminated by partitioning from underlying ground water pollution. Conversely, soil gas can be contaminated by partitioning from underlying ground water VOC plumes. This soil gas and aqueous phase interaction has motivated the popularity of soil gas sampling technology as a method of characterizing ground water VOC contamination. A finite-element-based numerical model was developed to accurately simulate the interaction between the soil gas phase and the aqueous phase. This interaction is complicated since the saturation of the aqueous phase varies dramatically across the capillary fringe. The two-phase flow equations for gas and water are used to describe the flow regime, while the advective-dispersive transport of the VOC is considered in both phases. Dissolution and volatilization from a non-mobile non-aqueous phase liquid is included as a volatile organic contaminant source. A deforming mesh allows the model to accurately track the water table movement, and a Eularian-Lagrangian formulation is used to control some of the numerical difficulties associated with the numerical solution of the advection-dispersion equation. An investigation into diffusion of a VOC from below the water table demonstrated that both the frequency and the magnitude of water table fluctuations have a profound influence on the degree of soil gas contamination. Two-dimensional large-scale, long-term simulations were performed to estimate the aqueous and soil gas phase plumes resulting from an immobilized trichloroethylene residual located in the unsaturated zone. The simulation results indicate that these plumes are very sensitive to the vertical position of the contaminant source. In addition, it was determined that seasonal fluctuations in soil gas VOC

  5. Rate processes in gas phase

    International Nuclear Information System (INIS)

    Hansen, C.F.

    1983-05-01

    Reaction-rate theory and experiment are given a critical review from the engineers' point of view. Rates of heavy-particle, collision-induced reaction in gas phase are formulated in terms of the cross sections and activation energies of the reaction. The effect of cross section function shape and of excited state contributions to the reaction both cause the slope of Arrhenius plots to differ from the true activation energy, except at low temperature. The master equations for chemically reacting gases are introduced, and dissociation and ionization reactions are shown to proceed primarily from excited states about kT from the dissociation or ionization limit. Collision-induced vibration, vibration-rotation, and pure rotation transitions are treated, including three-dimensional effects and conservation of energy, which have usually been ignored. The quantum theory of transitions at potential surface crossing is derived, and results are found to be in fair agreement with experiment in spite of some questionable approximations involved

  6. Toxicity of vapor phase petroleum contaminants to microbial degrader communities

    International Nuclear Information System (INIS)

    Long, S.C.; Davey, C.A.

    1994-01-01

    Petroleum products constitute the largest quantity of synthetic organic chemical products produced in the US. They are comprised of mostly hydrocarbon constituents from many different chemical classes including alkenes, cycloalkanes, aromatic compounds, and polyaromatic hydrocarbons. Many petroleum constituents are classified as volatile organic compounds or VOCs. Petroleum products also constitute a major portion of environmental pollution. One emerging technology, with promise for applications to VOCs in subsurface soil environments, is bioventing coupled with soil vapor extraction. These technologies involve volatilization of contaminants into the soil gas phase by injection and withdrawal of air. This air movement causes enhancement of the aerobic microbial degradation of the mobilized vapors by the indigenous populations. This study investigated the effects of exposure of mixed, subsurface microbial communities to vapor phase petroleum constituents or vapors of petroleum mixtures. Soil slurries were prepared and plated onto mineral salts agar plates and exposed to vapor phase contaminants at equilibrium with pure product. Representative n-alkane, branched alkane, cycloalkane, and aromatic compounds were tested as well as petroleum product mixtures. Vapor exposure altered the numbers and morphologies of the colonies enumerated when compared to controls. However, even at high, equilibrium vapor concentrations, microbial degrader populations were not completely inhibited

  7. Gas contaminant sampling apparatus and method

    International Nuclear Information System (INIS)

    Bradley, N.; Woolam, P.B.

    1985-01-01

    Monitoring for trace quantities of leaking particulate contaminants in air flow through a duct having an inner wall is effected by means of a continuously moving filter element carried by an endless conveyor, which extends across the duct within the confines of a casing through which a proportion of the air flow is drawn by a pump so that the air passes through the moving filter element. The accumulation of contaminants on the filter element is detected by a detector mounted in a liquid nitrogen-filled Dewar flask or the like. (author)

  8. Oil and gas site contamination risks : improved oversight needed

    International Nuclear Information System (INIS)

    2010-02-01

    British Columbia has seen record levels of activities in the oil and gas sector. Upstream petroleum processes include exploration, well completion and production. Site contamination can occur during all of these activities, resulting in potential environmental and human health impacts. Although well operators are responsible by law for site restoration, there is a potential risk that some operators will not fulfill their responsibilities, thereby leaving the province liable for the site restoration costs. In British Columbia, the BC Oil and Gas Commission (OGC) is responsible for managing these risks through oversight activities designed to ensure that industry meets its obligations. The OGC also manages the orphan sites reclamation fund. This report presented an audit of the OGC in order to determine if it is providing adequate oversight of upstream oil and gas site contamination risks. The audit examined whether the agency responsibilities are clear and whether the OGC is fully aware of the environmental and financial risks associated with upstream oil and gas site contamination. The audit also examined if the OGC has established appropriate procedures to oversee the risks and to inform the public of how effectively site contamination risks are being managed. The report presented the audit background, audit expectations, findings, conclusions and recommendations. It was concluded that the OGC's oversight of the environmental and financial risks associated with oil and gas site contamination needs improving. tabs., figs.

  9. Radon measurements over a natural-gas contaminated aquifer

    International Nuclear Information System (INIS)

    Palacios, D.; Fusella, E.; Avila, Y.; Salas, J.; Teixeira, D.; Fernández, G.; Salas, A.; Sajo-Bohus, L.; Greaves, E.; Barros, H.; Bolívar, M.; Regalado, J.

    2013-01-01

    Radon and thoron concentrations in soil pores in a gas production region of the Anzoategui State, Venezuela, were determined by active and passive methods. In this region, water wells are contaminated by natural gas and gas leaks exist in the nearby river. Based on soil gas Radon data surface hydrocarbon seeps were identified. Radon and thoron concentration maps show anomalously high values near the river gas leaks decreasing in the direction of water wells where natural gas is also detected. The area where the highest concentrations of 222 Rn were detected seems to indicate the surface projection of the aquifer contaminated with natural gas. The Radon/Thoron ratio revealed a micro-localized anomaly, indicating the area where the gas comes from deep layers of the subsoil. The radon map determined by the passive method showed a marked positive anomaly around abandoned gas wells. The high anomalous Radon concentration localized near the trails of ascending gas bubbles at the river indicates the zone trough where natural gases are ascending with greater ease, associated with a deep geological fault, being this the main source of methane penetration into the aquifer. It is suggested that the source of the natural gas may be due to leaks at deep sites along the structure of some of the abandoned wells located at the North-East of the studied area. - Highlights: ► High Radon/Thoron ratios were localized near the natural-gas emanations in a river. ► Natural gases are ascending trough a deep geological fault. ► Apparently, the radon anomaly shows the site where natural gas enters the aquifer. ► Natural gas source may be related to leaks in the structure of abandoned gas wells

  10. Phase transition in the hadron gas model

    International Nuclear Information System (INIS)

    Gorenstein, M.I.; Petrov, V.K.; Zinov'ev, G.M.

    1981-01-01

    A class of statistical models of hadron gas allowing an analytical solution is considered. A mechanism of a possible phase transition in such a system is found and conditions for its occurence are determined [ru

  11. Trace Contaminant Monitor for Air in Spacecraft, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A need exists for analyzers that can measure trace contaminants in air on board spacecraft. Toxic gas buildup can endanger the crew particularly during long...

  12. Micro GC's for Contaminant Monitoring in Spacecraft Air, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this proposal is to create new gas chromatographs (GCs) for contaminant monitoring in spacecraft air that do not require any reagents or special...

  13. Fuel Flexibility: Landfill Gas Contaminant Mitigation for Power Generation

    Energy Technology Data Exchange (ETDEWEB)

    Storey, John Morse [ORNL; Theiss, Timothy J [ORNL; Kass, Michael D [ORNL; FINNEY, Charles E A [ORNL; Lewis, Samuel [Oak Ridge National Laboratory (ORNL); Kaul, Brian C [ORNL; Besmann, Theodore M [ORNL; Thomas, John F [ORNL; Rogers, Hiram [ORNL; Sepaniak, Michael [University of Tennessee, Knoxville (UTK)

    2014-04-01

    This research project focused on the mitigation of silica damage to engine-based renewable landfill gas energy systems. Characterization of the landfill gas siloxane contamination, combined with characterization of the silica deposits in engines, led to development of two new mitigation strategies. The first involved a novel method for removing the siloxanes and other heavy contaminants from the landfill gas prior to use by the engines. The second strategy sought to interrupt the formation of hard silica deposits in the engine itself, based on inspection of failed landfill gas engine parts. In addition to mitigation, the project had a third task to develop a robust sensor for siloxanes that could be used to control existing and/or future removal processes.

  14. Condensed phase decomposition and gas phase combustion of hydrazinium nitroformate

    NARCIS (Netherlands)

    Dragomir, O.E.; Tummers, M.J.; Veen, E.H. van; Heijden, A.E.D.M. van der; Roekaerts, D.J.E.M.

    2009-01-01

    This paper presents the results of a series of experiments on the condensed phase decomposition and the gas phase combustion of hydrazinium nitroformate (HNF). The experiments include SEM analysis of quenched samples that showed evidence of the formation of a foam layer. FTIR spectrometry and mass

  15. Organic Contaminants Associated with the Extraction of Unconventional Gas. Risk Analysis in the Initial Phases of the Project; Contaminantes Orgánicos Asociados a la Extracción de Gas no Convencional. Análisis de Riesgos en las Fases Iniciales del Proyecto

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L.; Hurtado, A.; Recreo, F.; Eguilior, S.

    2015-07-01

    The latest technological advances in hydraulic fracturing and horizontal drilling are promoting a commercial scale extraction of unconventional fossil fuels in several regions of the world. Although there is still no commercial scale extraction in the Member States of the EU, potential stocks in some of them, as in the case of Spain, stimulate the need to carry out precautionary previous studies. These, based on the experience in the USA, will allow to define the characteristics that a priori should include a project of unconventional gas extraction, so that their safety is maximized by minimizing the likelihood of adverse effects on the environment. In unconventional gas production a fracturing fluid, typically water, with different types of additives is injected into the reservoir at very high pressure in order to create fractures to increase the porosity and permeability of the rock. In this scenario the flowback and produced water (water brought to the surface during the extraction of gas or oil) is usually a mixture of fluids injected and brines present in the repository. The quality of the flowback and produced water is variable. Its salinity varies from similar to drinking water to several times more saline than seawater. Furthermore, different compounds other than salt can be present in various amounts in the flowback and produced water: oil and other organic compounds, solids in suspension, bacteria, naturally occurring radioactive elements (NORM), and any of the elements injected with the hydraulic fracturing fluid. Due to the high variability of contaminants in the flowback and produced water as well as potentially large volumes involved, composition of flowback and produced water and the analysis of the risks associated with them is an important aspect to consider from the initial phases of project development of unconventional gas extraction. This report covers the risk analysis of an unconventional gas extraction project, the initial assessment of the

  16. Gas-Phase Infrared; JCAMP Format

    Science.gov (United States)

    SRD 35 NIST/EPA Gas-Phase Infrared; JCAMP Format (PC database for purchase)   This data collection contains 5,228 infrared spectra in the JCAMP-DX (Joint Committee for Atomic and Molecular Physical Data "Data Exchange") format.

  17. Method and system for gas flow mitigation of molecular contamination of optics

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, Gildardo; Johnson, Terry; Arienti, Marco; Harb, Salam; Klebanoff, Lennie; Garcia, Rudy; Tahmassebpur, Mohammed; Scott, Sarah

    2018-01-23

    A computer-implemented method for determining an optimized purge gas flow in a semi-conductor inspection metrology or lithography apparatus, comprising receiving a permissible contaminant mole fraction, a contaminant outgassing flow rate associated with a contaminant, a contaminant mass diffusivity, an outgassing surface length, a pressure, a temperature, a channel height, and a molecular weight of a purge gas, calculating a flow factor based on the permissible contaminant mole fraction, the contaminant outgassing flow rate, the channel height, and the outgassing surface length, comparing the flow factor to a predefined maximum flow factor value, calculating a minimum purge gas velocity and a purge gas mass flow rate from the flow factor, the contaminant mass diffusivity, the pressure, the temperature, and the molecular weight of the purge gas, and introducing the purge gas into the semi-conductor inspection metrology or lithography apparatus with the minimum purge gas velocity and the purge gas flow rate.

  18. Radiolytic gas generation in plutonium contaminated waste materials

    International Nuclear Information System (INIS)

    Kazanjian, A.R.

    1976-01-01

    Many plutonium contaminated waste materials decompose into gaseous products because of exposure to alpha radiation. The gases generated (usually hydrogen) over long-storage periods may create hazardous conditions. To determine the extent of such hazards, knowing the gas generation yields is necessary. These yields were measured by contacting some common Rocky Flats Plant waste materials with plutonium and monitoring the enclosed atmospheres for extensive periods of time. The materials were Plexiglas, polyvinyl chloride, glove-box gloves, machining oil, carbon tetrachloride, chlorothene VG solvent, Kimwipes (dry and wet), polyethylene, Dowex-1 resin, and surgeon's gloves. Both 239 Pu oxide and 238 Pu oxide were used as radiation sources. The gas analyses were made by mass spectrometry and the results obtained were the total gas generation, the hydrogen generation, the oxygen consumption rate, and the gas composition over the entire storage period. Hydrogen was the major gas produced in most of the materials. The total gas yields varied from 0.71 to 16 cm 3 (standard temperature pressure) per day per curie of plutonium. The oxygen consumption rates varied from 0.0088 to 0.070 millimoles per day per gram of plutonium oxide-239 and from 0.0014 to 0.0051 millimoles per day per milligram 238 Pu

  19. Ammonia gas transport and reactions in unsaturated sediments: Implications for use as an amendment to immobilize inorganic contaminants

    International Nuclear Information System (INIS)

    Zhong, L.; Szecsody, J.E.; Truex, M.J.; Williams, M.D.; Liu, Y.

    2015-01-01

    Highlights: • Ammonia transport can be predicted from gas movement and equilibrium partitioning. • Ammonia diffusion rate in unsaturated sediment is a function of water contents. • High pH induced by ammonia causes mineral dissolution and sequential precipitation. • Ammonia treatment effectively immobilized uranium from contaminated sediments. - Abstract: Use of gas-phase amendments for in situ remediation of inorganic contaminants in unsaturated sediments of the vadose zone may be advantageous, but there has been limited development and testing of gas remediation technologies. Treatment with ammonia gas has a potential for use in treating inorganic contaminants (such as uranium) because it induces a high pore-water pH, causing mineral dissolution and subsequent formation of stable precipitates that decrease the mobility of some contaminants. For field application of this treatment, further knowledge of ammonia transport in porous media and the geochemical reactions induced by ammonia treatment is needed. Laboratory studies were conducted to support calculations needed for field treatment design, to quantify advective and diffusive ammonia transport in unsaturated sediments, to evaluate inter-phase (gas/sediment/pore water) reactions, and to study reaction-induced pore-water chemistry changes as a function of ammonia delivery conditions, such as flow rate, gas concentration, and water content. Uranium-contaminated sediment was treated with ammonia gas to demonstrate U immobilization. Ammonia gas quickly partitions into sediment pore water and increases the pH up to 13.2. Injected ammonia gas advection front movement can be reasonably predicted by gas flow rate and equilibrium partitioning. The ammonia gas diffusion rate is a function of the water content in the sediment. Sodium, aluminum, and silica pore-water concentrations increase upon exposure to ammonia and then decline as aluminosilicates precipitate when the pH declines due to buffering. Up to 85% of

  20. Micro GC's for Contaminant Monitoring in Spacecraft Air, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Based on the successful separation of 20 compounds using a 1 m coated microcolumn in Phase I, we propose to design a new micro-gas chromatograph (microGC) system to...

  1. Removal of Dioxin Contamination for Gas Turbine Generator Set Repair

    Energy Technology Data Exchange (ETDEWEB)

    Fay, W. S.; Borah, R.E.

    2003-02-25

    Decontamination projects are typically undertaken in the interest of reducing disposal costs. This goal can be achieved because decontamination concentrates the contaminant into a smaller volume or changes its form so that a lower cost disposal technology becomes available. Less frequently, decontamination adds value back to the fouled structure or contaminated piece of equipment. This removal of dioxins from a gas turbine generator set is one of the latter cases. A multi-million dollar piece of equipment could have been destined for the scrap pile. Instead, an innovative, non-destructive decontamination technology, developed under EPA and DOE demonstration programs has was employed so that the set could repaired and put back into service. The TechXtractchemical decontamination technology reduced surface dioxin / furan concentrations from as high as 24,000 ng / m2 to less than 25 ng / m2 and below detection limits.

  2. Gas phase equilibrium structure of histamine.

    Science.gov (United States)

    Tikhonov, Denis S; Rykov, Anatolii N; Grikina, Olga E; Khaikin, Leonid S

    2016-02-17

    The first gas electron diffraction (GED) experiment for histamine was carried out. The equilibrium structure of histamine in the gas phase was determined on the basis of the data obtained. The refinement was also supported by the rotational constants obtained in previous studies [B. Vogelsanger, et al., J. Am. Chem. Soc., 1991, 113, 7864-7869; P. Godfrey, et al., J. Am. Chem. Soc., 1998, 120, 10724-10732] and quantum chemical calculations. The proposed mechanism of tautomerization by simultaneous intermolecular transfer of hydrogens in a histamine dimer helps to explain the distribution of tautomers in different experiments. The estimations of the conformational interconversion times provided the explanation for the absence of some conformers in the rotational spectroscopy experiments.

  3. Gas phase thermochemistry of organogermanium compounds

    Energy Technology Data Exchange (ETDEWEB)

    Engel, John P. [Iowa State Univ., Ames, IA (United States)

    1993-12-07

    A variety of silyl- and alkyl-germylene precursors have been synthesized and subsequently pyrolyzed in the gas phase. Arrhenius parameters were obtained employing a pulsed-stirred flow reactor for these unimolecular decompositions. These precursors are divided into two major categories by mechanism of germylene extrusion: α-elimination precursors and germylacetylenes. The extrusion of germylenes from germylacetylene precursors is of primary interest. A mechanism is proposed employing a germacyclopropene intermediate. Evidence supporting this mechanism is presented. In the process of exploring germylacetylenes as germylene precursors, an apparent dyatropic rearrangement between germanium and silicon was observed. This rearrangement was subsequently explored.

  4. Gas phase reactive collisions, experimental approach

    Directory of Open Access Journals (Sweden)

    Canosa A.

    2012-01-01

    Full Text Available Since 1937 when the first molecule in space has been identified, more than 150 molecules have been detected. Understanding the fate of these molecules requires having a perfect view of their photochemistry and reactivity with other partners. It is then crucial to identify the main processes that will produce and destroy them. In this chapter, a general view of experimental techniques able to deliver gas phase chemical kinetics data at low and very low temperatures will be presented. These techniques apply to the study of reactions between neutral reactants on the one hand and reactions involving charge species on the other hand.

  5. A study of gas contaminants and interaction with materials in RPC closed loop systems

    CERN Document Server

    Colafranceschi, S.; Benussi, L.; Bianco, S.; Passamonti, L.; Piccolo, D.; Pierluigi, D.; Russo, A.; Ferrini, M.; Greci, T.; Saviano, G.; Vendittozzi, C.; Abbrescia, M.; Calabria, C.; Colaleo, A.; Iaselli, G.; Maggi, M.; Nuzzo, S.; Pugliese, G.; Verwilligen, P.; Sharma, A.

    2012-01-01

    Resistive Plate Counters (RPC) detectors at the Large Hadron Collider (LHC) experiments use gas recirculation systems to cope with large gas mixture volumes and costs. In this paper a long-term systematic study about gas purifiers, gas contaminants and detector performance is discussed. The study aims at measuring the lifetime of purifiers with unused and used cartridge material along with contaminants release in the gas system. During the data-taking the response of several RPC double-gap detectors was monitored in order to characterize the correlation between dark currents, filter status and gas contaminants.

  6. Photocatalytical Decomposition of Contaminants on Thin Film Gas Sensors

    International Nuclear Information System (INIS)

    Radecka, M.; Lyson, B.; Lubecka, M.; Czapla, A.; Zakrzewska, K.

    2010-01-01

    Gas sensing materials have been prepared in a form of TiO 2 -SnO 2 thin films by rf reactive sputtering from Ti:SnO 2 and Sn:TiO 2 targets. Material studies have been performed by scanning electron microscopy, atomic force microscopy, X-ray diffraction at grazing incidence, Moessbauer spectroscopy, X-ray photoelectron spectroscopy and optical spectrophotometry. Dynamic gas sensing responses have been recorded as reproducible changes in the electrical resistance upon introduction of hydrogen at a partial pressure of 100-6000 ppm over a wide temperature range 473-873 K. Contamination experiments have been carried out with the motor oil (40 vol.% solution in CCl 4 ) in order to study the effect of UV light illumination on the gas sensor response. Optical spectroscopy has been applied to monitor the photodecomposition of the test compound, bromothymol blue. The Electronic Nose, ALPHA MOS FOX 4000 has been used in order to differentiate between different groups of motor oil vapors. (author)

  7. Vaccum Gas Tungsten Arc Welding, phase 1

    Science.gov (United States)

    Weeks, J. L.; Krotz, P. D.; Todd, D. T.; Liaw, Y. K.

    1995-01-01

    This two year program will investigate Vacuum Gas Tungsten Arc Welding (VGTAW) as a method to modify or improve the weldability of normally difficult-to-weld materials. VGTAW appears to offer a significant improvement in weldability because of the clean environment and lower heat input needed. The overall objective of the program is to develop the VGTAW technology and implement it into a manufacturing environment that will result in lower cost, better quality and higher reliability aerospace components for the space shuttle and other NASA space systems. Phase 1 of this program was aimed at demonstrating the process's ability to weld normally difficult-to-weld materials. Phase 2 will focus on further evaluation, a hardware demonstration and a plan to implement VGTAW technology into a manufacturing environment. During Phase 1, the following tasks were performed: (1) Task 11000 Facility Modification - an existing vacuum chamber was modified and adapted to a GTAW power supply; (2) Task 12000 Materials Selection - four difficult-to-weld materials typically used in the construction of aerospace hardware were chosen for study; (3) Task 13000 VGTAW Experiments - welding experiments were conducted under vacuum using the hollow tungsten electrode and evaluation. As a result of this effort, two materials, NARloy Z and Incoloy 903, were downselected for further characterization in Phase 2; and (4) Task 13100 Aluminum-Lithium Weld Studies - this task was added to the original work statement to investigate the effects of vacuum welding and weld pool vibration on aluminum-lithium alloys.

  8. Radon as an indicator of environmental contamination by hydrocarbons in free-phase

    International Nuclear Information System (INIS)

    Mateus, Crislene

    2016-01-01

    Contaminated sites by NAPL (Non-Aqueous Phase-Liquids) may lead to safety risks to human health and to ecosystems, restrictions to urban development and decrease of real estate value. This work used the radon gas as an indicator for the analysis of subsurface soil gas, once this noble gas presents good solubility in a wide range of NAPL, being partially retained in the NAPL contamination. Therefore, a decrease of the activity of radon in the contaminated soil gas can be expected, due to the high capacity of partitioning of radon in NAPL, which allows that the NAPL retain part of the radon previously available in the soil pores. The survey was carried out at a disused industry, contaminated by low volatile NAPL, located at southeast of Sao Paulo city, from June/14 to May/15. Radon was evaluated by passive detection methodology with CR-39 solid state nuclear track detectors (SSNTD) in ten monitoring stations installed in the contaminated area investigated and named 'A' to 'J'. Radon concentrations average for the eight monitoring stations at non-contaminated locations varied from (22 ± 4) kBq.m -3 to (39 ± 4) kBq.m -3 . For the two monitoring stations assumed as contaminated locations, radon concentrations average were (1.4 ± 0.4) kBq.m -3 and (13 ± 9) kBq.m -3 . The results have shown good agreement between the used method and the conventional environmental investigation techniques, for the majority of the monitoring stations in different seasons. Results obtained with CR-39 detectors varied over the exposure time due to the different seasons. No relation was observed between radon activity concentrations and rain volume accumulated over the different CR-39 exposure times. The lowest 222 Rn activity concentrations occurred in 'G' and 'H' monitoring stations, also verifying by gamma-ray spectrometry, that the low activities are not related to the activity concentration of its father 226 Ra from the 238 U decay chain

  9. Factors affecting gas migration and contaminant redistribution in heterogeneous porous media subject to electrical resistance heating.

    Science.gov (United States)

    Munholland, Jonah L; Mumford, Kevin G; Kueper, Bernard H

    2016-01-01

    A series of intermediate-scale laboratory experiments were completed in a two-dimensional flow cell to investigate gas production and migration during the application of electrical resistance heating (ERH) for the removal of dense non-aqueous phase liquids (DNAPLs). Experiments consisted of heating water in homogeneous silica sand and heating 270 mL of trichloroethene (TCE) and chloroform (CF) DNAPL pools in heterogeneous silica sands, both under flowing groundwater conditions. Spatial and temporal distributions of temperature were measured using thermocouples and observations of gas production and migration were collected using front-face image capture throughout the experiments. Post-treatment soil samples were collected and analyzed to assess DNAPL removal. Results of experiments performed in homogeneous sand subject to different groundwater flow rates showed that high groundwater velocities can limit subsurface heating rates. In the DNAPL pool experiments, temperatures increased to achieve DNAPL-water co-boiling, creating estimated gas volumes of 131 and 114 L that originated from the TCE and CF pools, respectively. Produced gas migrated vertically, entered a coarse sand lens and subsequently migrated laterally beneath an overlying capillary barrier to outside the heated treatment zone where 31-56% of the original DNAPL condensed back into a DNAPL phase. These findings demonstrate that layered heterogeneity can potentially facilitate the transport of contaminants outside the treatment zone by mobilization and condensation of gas phases during ERH applications. This underscores the need for vapor phase recovery and/or control mechanisms below the water table during application of ERH in heterogeneous porous media during the co-boiling stage, which occurs prior to reaching the boiling point of water. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Soil biotransformation of thiodiglycol, the hydrolysis product of mustard gas: understanding the factors governing remediation of mustard gas contaminated soil.

    Science.gov (United States)

    Li, Hong; Muir, Robert; McFarlane, Neil R; Soilleux, Richard J; Yu, Xiaohong; Thompson, Ian P; Jackman, Simon A

    2013-02-01

    Thiodiglycol (TDG) is both the precursor for chemical synthesis of mustard gas and the product of mustard gas hydrolysis. TDG can also react with intermediates of mustard gas degradation to form more toxic and/or persistent aggregates, or reverse the pathway of mustard gas degradation. The persistence of TDG have been observed in soils and in the groundwater at sites contaminated by mustard gas 60 years ago. The biotransformation of TDG has been demonstrated in three soils not previously exposed to the chemical. TDG biotransformation occurred via the oxidative pathway with an optimum rate at pH 8.25. In contrast with bacteria isolated from historically contaminated soil, which could degrade TDG individually, a consortium of three bacterial strains isolated from the soil never contaminated by mustard gas was able to grow on TDG in minimal medium and in hydrolysate derived from an historical mustard gas bomb. Exposure to TDG had little impacts on the soil microbial physiology or on community structure. Therefore, the persistency of TDG in soils historically contaminated by mustard gas might be attributed to the toxicity of mustard gas to microorganisms and the impact to soil chemistry during the hydrolysis. TDG biodegradation may form part of a remediation strategy for mustard gas contaminated sites, and may be enhanced by pH adjustment and aeration.

  11. Analytical characterization of contaminated soils from former manufactured gas plants

    International Nuclear Information System (INIS)

    Haeseler, F.; Blanchet, D.; Vandecasteele, J.P.; Druelle, V.; Werner, P.; Technische Univ., Dresden,

    1999-01-01

    Detailed analytical characterization of the organic matter (OM) of aged polluted soils from five former manufactured gas plants (MGP) and of two coal tars was completed. It was aimed at obtaining information relevant to the physicochemical state of the polycyclic aromatic hydrocarbon (PAH) pollutants and to their in-situ evolution in time. Overall characterization of total OM (essentially polluting OM) was carried out directly on soil samples with or without prior extraction with solvent. It involved a technique of pyrolysis/oxidation coupled to flame ionization/thermal conductivity detection. Extracts in solvent were fractionated by liquid chromatography into saturated hydrocarbons, PAH, and resins, the first two fractions being further characterized by gas chromatography and mass spectrometry. The compositions of OM of soils were found to be very similar. A total of 28% of organic carbon, including all PAH, was extractable by solvent. The compositions of coal tars were qualitatively similar to those of OM of MGP soils but with a higher proportion (48%) of total extractable OM and of PAH, in particular lower PAH. Contamination of MGP soils appeared essentially as coal tar having undergone natural attenuation. The constant association of PAH with heavy OM in MGP soils is important with respect to the mobility and bioaccessibility of these pollutants

  12. Phase transitions in a gas of anyons

    International Nuclear Information System (INIS)

    MacKenzie, R.; Nebia-Rahal, F.; Paranjape, M. B.; Richer, J.

    2010-01-01

    We continue our numerical Monte Carlo simulation of a gas of closed loops on a 3 dimensional lattice, however, now in the presence of a topological term added to the action which corresponds to the total linking number between the loops. We compute the linking number using a novel approach employing certain notions from knot theory. Adding the topological term converts the particles into anyons. Interpreting the model as an effective theory that describes the 2+1-dimensional Abelian Higgs model in the asymptotic strong-coupling regime, the topological linking number simply corresponds to the addition to the action of the Chern-Simons term. The system continues to exhibit a phase transition as a function of the vortex mass as it becomes small. We find the following new results. The Chern-Simons term has no effect on the Wilson loop. On the other hand, it does effect the 't Hooft loop of a given configuration, adding the linking number of the 't Hooft loop with all of the dynamical vortex loops. We find the unexpected result that both the Wilson loop and the 't Hooft loop exhibit a perimeter law even though there are no massless particles in the theory, in both phases of the theory. It should be noted that our method suffers from numerical instabilities if the coefficient of the Chern-Simons term is too large; thus, we have restricted our results to small values of this parameter. Furthermore, interpreting the lattice loop gas as an effective theory describing the Abelian Higgs model is only known to be true in the infinite coupling limit; for strong but finite coupling this correspondence is only a conjecture, the validity of which is beyond the scope of this article.

  13. Solid–gaseous phase transformation of elemental contaminants during the gasification of biomass

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Ying; Ameh, Abiba [Centre for Bioenergy & Resource Management, School of Energy, Environment & Agrifood, Cranfield University, Cranfield MK43 0AL (United Kingdom); Lei, Mei [Centre for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China); Duan, Lunbo [Key Laboratory of Energy Thermal Conversion and Control, Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096 (China); Longhurst, Philip, E-mail: P.J.Longhurst@cranfield.ac.uk [Centre for Bioenergy & Resource Management, School of Energy, Environment & Agrifood, Cranfield University, Cranfield MK43 0AL (United Kingdom)

    2016-09-01

    Disposal of plant biomass removed from heavy metal contaminated land via gasification achieves significant volume reduction and can recover energy. However, these biomass often contain high concentrations of heavy metals leading to hot-corrosion of gasification facilities and toxic gaseous emissions. Therefore, it is of significant interest to gain a further understanding of the solid–gas phase transition of metal(loid)s during gasification. Detailed elemental analyses (C, H, O, N and key metal/metalloid elements) were performed on five plant species collected from a contaminated site. Using multi-phase equilibria modelling software (MTDATA), the analytical data allows modelling of the solid/gas transformation of metal(loid)s during gasification. Thermodynamic modelling based on chemical equilibrium calculations was carried out in this study to predict the fate of metal(loid) elements during typical gasification conditions and to show how these are influenced by metal(loid) composition in the biomass and operational conditions. As, Cd, Zn and Pb tend to transform to their gaseous forms at relatively low temperatures (< 1000 °C). Ni, Cu, Mn and Co converts to gaseous forms within the typical gasification temperature range of 1000–1200 °C. Whereas Cr, Al, Fe and Mg remain in solid phase at higher temperatures (> 1200 °C). Simulation of pressurised gasification conditions shows that higher pressures increase the temperature at which solid-to-gaseous phase transformations takes place. - Highlights: • Disposal of plants removed from metal contaminated land raises environmental concerns • Plant samples collected from a contaminated site are shown to contain heavy metals. • Gasification is suitable for plant disposal and its emission is modelled by MTDATA. • As, Cd, Zn and Pb are found in gaseous emissions at a low process temperature. • High pressure gasification can reduce heavy metal elements in process emission.

  14. Application of biodegradation screening protocol to contaminated soils from manufactured gas plant sites

    International Nuclear Information System (INIS)

    Smith, J.R.; Nakles, D.V.; Cushey, M.A.; Morgan, D.J.; Linz, D.G.

    1990-01-01

    Bioremediation (i.e., land treatment) has been demonstrated to be a viable option for treating a variety of soils contamianted with organics. Conventional treatability studies utilize soil microcosm experiments to evaluate the potential for bioremediation of specific contaminated soils. Unfortunately, soil microcosms take from 4- to 6-months to complete and do not fully exploit the current understanding of the bioremediation process. This paper describes a treatability protocol that investigates underlying mechanisms and can be completed in 2- to 3-months. It is believed that soil bioremediation is governed by the sequential processes of contanate desorption from the soil into the aqueous phase and subsequent oxidation by microorganisms. The relative importance of each process depends upon the contaminant and soil. Accordingly, the treatability protocol has three steps. In the first step, tests are performed to determine soil characteristics. In the second step, tests are performed to characterize the desorption of contaminants from the soil. In the third step, the potential for biological oxidaiton is evaluated with a soil-water slurry reactor that maximizes desorption and provides an optimum environment for microbial growth. This paper provides a thorough discussion of the laboratory protocol including the primary theoretical tenets which serve as its basis. Preliminary procedures and results are presented for soils contaminated with manufactured gas plant (MGP) wastes. Particular attention is focused on biodegradation of polynuclear aromatic hydrocarbons (PAHs)

  15. Solid-gaseous phase transformation of elemental contaminants during the gasification of biomass.

    Science.gov (United States)

    Jiang, Ying; Ameh, Abiba; Lei, Mei; Duan, Lunbo; Longhurst, Philip

    2016-09-01

    Disposal of plant biomass removed from heavy metal contaminated land via gasification achieves significant volume reduction and can recover energy. However, these biomass often contain high concentrations of heavy metals leading to hot-corrosion of gasification facilities and toxic gaseous emissions. Therefore, it is of significant interest to gain a further understanding of the solid-gas phase transition of metal(loid)s during gasification. Detailed elemental analyses (C, H, O, N and key metal/metalloid elements) were performed on five plant species collected from a contaminated site. Using multi-phase equilibria modelling software (MTDATA), the analytical data allows modelling of the solid/gas transformation of metal(loid)s during gasification. Thermodynamic modelling based on chemical equilibrium calculations was carried out in this study to predict the fate of metal(loid) elements during typical gasification conditions and to show how these are influenced by metal(loid) composition in the biomass and operational conditions. As, Cd, Zn and Pb tend to transform to their gaseous forms at relatively low temperatures (gasification temperature range of 1000-1200°C. Whereas Cr, Al, Fe and Mg remain in solid phase at higher temperatures (>1200°C). Simulation of pressurised gasification conditions shows that higher pressures increase the temperature at which solid-to-gaseous phase transformations takes place. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  16. Resolving Gas-Phase Metallicity In Galaxies

    Science.gov (United States)

    Carton, David

    2017-06-01

    Chapter 2: As part of the Bluedisk survey we analyse the radial gas-phase metallicity profiles of 50 late-type galaxies. We compare the metallicity profiles of a sample of HI-rich galaxies against a control sample of HI-'normal' galaxies. We find the metallicity gradient of a galaxy to be strongly correlated with its HI mass fraction {M}{HI}) / {M}_{\\ast}). We note that some galaxies exhibit a steeper metallicity profile in the outer disc than in the inner disc. These galaxies are found in both the HI-rich and control samples. This contradicts a previous indication that these outer drops are exclusive to HI-rich galaxies. These effects are not driven by bars, although we do find some indication that barred galaxies have flatter metallicity profiles. By applying a simple analytical model we are able to account for the variety of metallicity profiles that the two samples present. The success of this model implies that the metallicity in these isolated galaxies may be in a local equilibrium, regulated by star formation. This insight could provide an explanation of the observed local mass-metallicity relation. Chapter 3 We present a method to recover the gas-phase metallicity gradients from integral field spectroscopic (IFS) observations of barely resolved galaxies. We take a forward modelling approach and compare our models to the observed spatial distribution of emission line fluxes, accounting for the degrading effects of seeing and spatial binning. The method is flexible and is not limited to particular emission lines or instruments. We test the model through comparison to synthetic observations and use downgraded observations of nearby galaxies to validate this work. As a proof of concept we also apply the model to real IFS observations of high-redshift galaxies. From our testing we show that the inferred metallicity gradients and central metallicities are fairly insensitive to the assumptions made in the model and that they are reliably recovered for galaxies

  17. Options for cleaning up subsurface contamination at Alberta sour gas plants

    International Nuclear Information System (INIS)

    Hardisty, P.; Dabrowski, T.L.

    1992-01-01

    At the conclusion of two major phases of a study on subsurface treatment technologies for Alberta sour gas plants, a candidate site was selected for a remediation technologies demonstration project. The plant has an extensive groundwater monitoring network in place, monitoring records for a period exceeding 10 years, ten recovery wells with aquifer test data and four reinjection wells. Hydrogeological exploration determined the presence and delineated a plume of free phase natural gas condensate. Aquifer remediation efforts at the site began in 1990 with the installation of recovery wells. Recovered groundwater was treated using a pilot scale air stripping system with pretreatment for iron, manganese and hardness. Dual pump system, water depression and free product skimmers were installed in the wells and tested. The nature and extent of contamination, study methodology, technology-dependent criteria, assessment of technology, and conceptual design are discussed for the three demonstration projects selected, which are enhanced soil vapour extraction with off-gas treatment, pump-and-treat with soil vapour extraction, biological treatment and air sparging, and treatment of dissolved process chemicals by advanced oxidation. 5 refs., 1 fig., 1 tab

  18. Airborne Multi-Gas Sensor, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Mesa Photonics has developed laser-based gas sensor technology compatible with UAV deployment. Our Airborne MUlti-Gas Sensor (AMUGS) technology is based upon...

  19. Comparison of catalytic ethylene polymerization in slurry and gas phase

    NARCIS (Netherlands)

    Daftaribesheli, Majid

    2009-01-01

    Polyethylene (PE) with the annual consumption of 70 million tones in 2007 is mostly produced in slurry, gas-phase or combination of both processes. This work focuses on a comparison between the slurry and gas phase processes. Why does PE produced in theses two processes can show extremely different

  20. Carbon Nanotube Gas Sensor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Sensing gas molecules is critical to environmental monitoring, control of chemical processes, space missions as well as agricultural and medical applications....

  1. Active Gas Regenerative Liquefier, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We offer a novel liquefier that has the potential to simultaneously increase thermodynamic efficiency and significantly reduce complexity. The ?active gas...

  2. Atmospheric contamination by pesticides: Determination in the liquid, gaseous and particulate phases.

    Science.gov (United States)

    Millet, M; Wortham, H; Sanusi, A; Mirabel, P

    1997-01-01

    Between 1991 and 1993, 18 fogwater samples, 31 rainwater samples and 17 atmosphere (gas and particles) samples were analysed for 13 pesticides (pp'DDT,pp'DDD,pp'DDE, aldrin, dieldrin, lindane, hexachlorobenzene, fenpropathrin, mecoprop, methyl-parathion, atrazine, isoproturon and aldicarb). The samples were collected in a rural area where some of the compounds are in use (experimental INRA farm, "Institut National de la Recherche Agronomique" in Colmar, Eastern France, 80,000 inhabitants). This paper briefly presents the analytical methodology used and, in detail, the contamination level of the different atmospheric phases. The contamination levels are roughly constant throughout the year in all the atmospheric phases and the most abundant pesticides are those commonly used on the experimental INRA farm and other surrounding farms. Nevertheless, some pesticides not used since the 1970s such as 1,1-Bis(4-chlorophenyl)-2,2,2-trichloroethane (pp'DDT) and 2,2-Bis(4-chlorophenyl)-1,1-dichloroethane (pp 'DDD) are also detected in the atmosphere of Colmar. A small increase in the pesticide concentrations in the atmosphere (gas and particles) was observed during treatments.

  3. The nature of ionic liquids in the gas phase.

    Science.gov (United States)

    Leal, João P; Esperança, José M S S; da Piedade, Manuel E Minas; Lopes, José N Canongia; Rebelo, Luís P N; Seddon, Kenneth R

    2007-07-19

    Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) experiments showed that when aprotic ionic liquids vaporize under pressure and temperature conditions similar to those of a reduced-pressure distillation, the gas phase is composed of discrete anion-cation pairs. The evolution of the mass spectrometric signals recorded during fractional distillations of binary ionic liquid mixtures allowed us to monitor the changes of the gas-phase composition and the relative volatility of the components. In addition, we have studied a protic ionic liquid, and demonstrated that it exists as separated neutral molecules in the gas phase.

  4. Residence time distribution of the gas phase in a mechanically agitated gas-liquid reactor

    NARCIS (Netherlands)

    Thijert, M.P.G.; Oyevaar, M.H.; Kuper, W.J.; Westerterp, K.R.

    1992-01-01

    In this study we present a measuring method and extensive experimental data on the gas phase RTD in a mechanically agitated gas-liquid reactor with standard dimensions over a wide range of superficial gas velocities, agitation rates and agitator sizes. The results are modelled successfully, using

  5. Airborne Multi-Gas Sensor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Mesa Photonics proposes to develop an Airborne Multi-Gas Sensor (AMUGS) based upon two-tone, frequency modulation spectroscopy (TT-FMS). Mesa Photonics has developed...

  6. The Influence of Mixing in High Temperature Gas Phase Reactions

    DEFF Research Database (Denmark)

    Østberg, Martin

    1996-01-01

    The objective of this thesis is to describe the mixing in high temperature gas phase reactions.The Selective Non-Catalytic Reduction of NOx (referred as the SNR process) using NH3 as reductant was chosen as reaction system. This in-furnace denitrification process is made at around 1200 - 1300 K...... diffusion. The SNR process is simulated using the mixing model and an empirical kinetic model based on laboratory experiments.A bench scale reactor set-up has been built using a natural gas burner to provide the main reaction gas. The set-up has been used to perform an experimental investigation...... of the mixing in the SNR process using injection of NH3 with carrier gas into the flue gas in crossflow by a quartz nozzle.Experiments were made with variation in NH3 flow, carrier gas flow, carrier gas composition (O2 concentration) and reactor temperature. Natural gas has been used as an addition...

  7. Headspace Solid-Phase Microextraction Coupled with Gas ...

    African Journals Online (AJOL)

    contact temperature measurement system (ONTMS). Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used to analyze the volatile composition of raw FCP and its various ...

  8. Reticulated Vitreous Carbon Electrodes for Gas Phase Pulsed Corona Reactors

    National Research Council Canada - National Science Library

    Locke, B

    1998-01-01

    A new design for gas phase pulsed corona reactors incorporating reticulated vitreous carbon electrodes is demonstrated to be effective for the removal of nitrogen oxides from synthetic air mixtures...

  9. Reticulated Vitreous Carbon Electrodes for Gas Phase Pulsed Corona Reactors

    National Research Council Canada - National Science Library

    LOCKE, B

    1999-01-01

    A new design for gas phase pulsed corona reactors incorporating reticulated vitreous carbon electrodes is demonstrated to be effective for the removal of nitrogen oxides from synthetic air mixtures...

  10. Ionization of Gas-Phase Polycyclic Aromatic Hydrocarbons in Electrospray Ionization Coupled with Gas Chromatography.

    Science.gov (United States)

    Cha, Eunju; Jeong, Eun Sook; Han, Sang Beom; Cha, Sangwon; Son, Junghyun; Kim, Sunghwan; Oh, Han Bin; Lee, Jaeick

    2018-03-20

    Herein, gas-phase polycyclic aromatic hydrocarbons (PAHs) as nonpolar compounds were ionized to protonated molecular ions [M + H] + without radical cations and simultaneously analyzed using gas chromatography (GC)/electrospray ionization (ESI)-tandem mass spectrometry (MS/MS). The ionization profile, dissociation, and sensitivity were first investigated to understand the significant behavior of gas-phase PAHs under ESI. The formation of protonated molecular ions of PAHs was distinguished according to the analyte phase and ESI spray solvents. The protonated PAHs exhibited characteristic dissociations, such as H-loss, H 2 -loss, and acetylene-loss, via competition of internal energy. In addition, GC/ESI-MS/MS resulted in relatively lower concentration levels (better sensitivity) for the limits-of-detection (LODs) of PAHs than liquid chromatography (LC)/ESI-MS/MS, and it seems to result from the characteristic ionization mechanism of the gas-phase analyte under ESI. Furthermore, the LODs of gas-phase PAHs depended on molecular weight and proton affinity (PA). Consequently, we demonstrated the relationship among the analyte phases, sensitivities, and structural characteristics (molecular weight and PA) under ESI. The gas-phase PAHs provided enhanced protonation efficiency and sensitivity using GC/ESI-MS/MS, as their molecular weight and PA increased. Based on these results, we offered important information regarding the behavior of gas-phase analytes under ESI. Therefore, the present GC/ESI-MS/MS method has potential as an alternative method for simultaneous analysis of PAHs.

  11. Potential effect of natural gas wells on alluvial groundwater contamination at the Kansas City Plant

    Energy Technology Data Exchange (ETDEWEB)

    Pickering, D.A.; Laase, A.D. [Oak Ridge National Lab., TN (United States); Locke, D.A. [Oak Ridge Inst. for Science and Education, TN (United States)

    1993-05-01

    This report is the result of a request for further information about several abandoned natural gas wells at the US Department of Energy`s Kansas City Plant (KCP). The request was prompted by an old map showing several, possibly eight, natural gas wells located under or near what is now the southeast corner of the Main Manufacturing Building at KCP. Volatile organic compound contamination in the alluvial aquifer surrounding the gas wells might possibly contaminate the bedrock aquifer if the gas wells still exist as conduits. Several circumstances exist that make it doubtful that contamination is entering the bedrock aquifers: (1) because regional groundwater flow in the bedrock beneath the KCP is expected to be vertically upward, contaminants found in the alluvial aquifer should not migrate down the old wells; (2) because of the low hydraulic conductivity of the bedrock units, contaminant transport would be extremely slow if the contaminants were migrating down the wells; and (3) casing, apparently set through the alluvium in all of the wells, would have deteriorated and may have collapsed; if the casing collapsed, the silty clays in the alluvium would also collapse and seal the well. No definitive information has been discovered about the exact location of the wells. No further search for or consideration of the old gas wells is recommended.

  12. Potential effect of natural gas wells on alluvial groundwater contamination at the Kansas City Plant

    Energy Technology Data Exchange (ETDEWEB)

    Pickering, D.A.; Laase, A.D. (Oak Ridge National Lab., TN (United States)); Locke, D.A. (Oak Ridge Inst. for Science and Education, TN (United States))

    1993-05-01

    This report is the result of a request for further information about several abandoned natural gas wells at the US Department of Energy's Kansas City Plant (KCP). The request was prompted by an old map showing several, possibly eight, natural gas wells located under or near what is now the southeast corner of the Main Manufacturing Building at KCP. Volatile organic compound contamination in the alluvial aquifer surrounding the gas wells might possibly contaminate the bedrock aquifer if the gas wells still exist as conduits. Several circumstances exist that make it doubtful that contamination is entering the bedrock aquifers: (1) because regional groundwater flow in the bedrock beneath the KCP is expected to be vertically upward, contaminants found in the alluvial aquifer should not migrate down the old wells; (2) because of the low hydraulic conductivity of the bedrock units, contaminant transport would be extremely slow if the contaminants were migrating down the wells; and (3) casing, apparently set through the alluvium in all of the wells, would have deteriorated and may have collapsed; if the casing collapsed, the silty clays in the alluvium would also collapse and seal the well. No definitive information has been discovered about the exact location of the wells. No further search for or consideration of the old gas wells is recommended.

  13. Potential effect of natural gas wells on alluvial groundwater contamination at the Kansas City Plant

    International Nuclear Information System (INIS)

    Pickering, D.A.; Laase, A.D.; Locke, D.A.

    1993-05-01

    This report is the result of a request for further information about several abandoned natural gas wells at the US Department of Energy's Kansas City Plant (KCP). The request was prompted by an old map showing several, possibly eight, natural gas wells located under or near what is now the southeast corner of the Main Manufacturing Building at KCP. Volatile organic compound contamination in the alluvial aquifer surrounding the gas wells might possibly contaminate the bedrock aquifer if the gas wells still exist as conduits. Several circumstances exist that make it doubtful that contamination is entering the bedrock aquifers: (1) because regional groundwater flow in the bedrock beneath the KCP is expected to be vertically upward, contaminants found in the alluvial aquifer should not migrate down the old wells; (2) because of the low hydraulic conductivity of the bedrock units, contaminant transport would be extremely slow if the contaminants were migrating down the wells; and (3) casing, apparently set through the alluvium in all of the wells, would have deteriorated and may have collapsed; if the casing collapsed, the silty clays in the alluvium would also collapse and seal the well. No definitive information has been discovered about the exact location of the wells. No further search for or consideration of the old gas wells is recommended

  14. Electron spectrometer for gas-phase spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bozek, J.D.; Schlachter, A.S. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    An electron spectrometer for high-resolution spectroscopy of gaseous samples using synchrotron radiation has been designed and constructed. The spectrometer consists of a gas cell, cylindrical electrostatic lens, spherical-sector electron energy analyzer, position-sensitive detector and associated power supplies, electronics and vacuum pumps. Details of the spectrometer design are presented together with some representative spectra.

  15. Space station contamination control study: Internal combustion, phase 1

    Science.gov (United States)

    Ruggeri, Robert T.

    1987-01-01

    Contamination inside Space Station modules was studied to determine the best methods of controlling contamination. The work was conducted in five tasks that identified existing contamination control requirements, analyzed contamination levels, developed outgassing specification for materials, wrote a contamination control plan, and evaluated current materials of offgassing tests used by NASA. It is concluded that current contamination control methods can be made to function on the Space Station for up to 1000 days, but that current methods are deficient for periods longer than about 1000 days.

  16. Evaluating a groundwater supply contamination incident attributed to Marcellus Shale gas development.

    Science.gov (United States)

    Llewellyn, Garth T; Dorman, Frank; Westland, J L; Yoxtheimer, D; Grieve, Paul; Sowers, Todd; Humston-Fulmer, E; Brantley, Susan L

    2015-05-19

    High-volume hydraulic fracturing (HVHF) has revolutionized the oil and gas industry worldwide but has been accompanied by highly controversial incidents of reported water contamination. For example, groundwater contamination by stray natural gas and spillage of brine and other gas drilling-related fluids is known to occur. However, contamination of shallow potable aquifers by HVHF at depth has never been fully documented. We investigated a case where Marcellus Shale gas wells in Pennsylvania caused inundation of natural gas and foam in initially potable groundwater used by several households. With comprehensive 2D gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS), an unresolved complex mixture of organic compounds was identified in the aquifer. Similar signatures were also observed in flowback from Marcellus Shale gas wells. A compound identified in flowback, 2-n-Butoxyethanol, was also positively identified in one of the foaming drinking water wells at nanogram-per-liter concentrations. The most likely explanation of the incident is that stray natural gas and drilling or HF compounds were driven ∼ 1-3 km along shallow to intermediate depth fractures to the aquifer used as a potable water source. Part of the problem may have been wastewaters from a pit leak reported at the nearest gas well pad-the only nearby pad where wells were hydraulically fractured before the contamination incident. If samples of drilling, pit, and HVHF fluids had been available, GCxGC-TOFMS might have fingerprinted the contamination source. Such evaluations would contribute significantly to better management practices as the shale gas industry expands worldwide.

  17. Protection of atmospheric air against radioactive gas and aerosol contaminants

    International Nuclear Information System (INIS)

    Zykova, A.S.

    1984-01-01

    Measures for contamination protection of atmospheric air subdivided into active and passive ones, are considered. The active measures envisage: development and application of waste-free flowsheets, use of flowsheets which restrict formation of gaseous-aerosol discharges; application of highly efficient treatment facilities torage. Dispersion of radioactive substances, released with discharges to the atmosphere, using high stacks; development of the corresponding site-selection solutions and arrangement of sanitary protective zones belong to passive measures. Measures for protection of atmospheric air also include waste and air contamination monitoring. The measures described are considered as applied to NPPs

  18. FORTRAN program for calculating liquid-phase and gas-phase thermal diffusion column coefficients

    International Nuclear Information System (INIS)

    Rutherford, W.M.

    1980-01-01

    A computer program (COLCO) was developed for calculating thermal diffusion column coefficients from theory. The program, which is written in FORTRAN IV, can be used for both liquid-phase and gas-phase thermal diffusion columns. Column coefficients for the gas phase can be based on gas properties calculated from kinetic theory using tables of omega integrals or on tables of compiled physical properties as functions of temperature. Column coefficients for the liquid phase can be based on compiled physical property tables. Program listings, test data, sample output, and users manual are supplied for appendices

  19. Catalytic combustion in gas stoves - Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Hjelm, Anna-Karin [CATATOR AB, Lund (Sweden)

    2003-06-01

    Several independent studies show that gas stoves to some degree contribute to the indoor emissions of NO{sub x} especially in situations were the ventilation flow is poor. The peak-NO{sub x} concentrations can reach several hundred ppb but the integral concentration seldom exceeds about 20 - 50 ppb, which corresponds to an indoor-outdoor ratio of about 1 - 2.5. Epidemiological studies indicate increasing problems with respiratory symptoms in sensitive people at concentrations as low as 15 ppb of NO{sub 2}. Consequently, the NO{sub x}-concentration in homes where gas stoves are used is high enough to cause health effects. However, in situations where the ventilation flow is high (utilisation of ventilation hoods) the NO{sub x}-emissions are not likely to cause any health problems. This study has been aimed at investigating the possibilities to reduce the NO{sub x} emissions from gas stoves by replacing the conventional flame combustion with catalytic combustion. The investigation is requested by Swedish Gas Center, and is a following-up work of an earlier conducted feasibility study presented in April-2002. The present investigation reports on the possibility to use cheap and simple retro-fit catalytic design suggestions for traditional gas stoves. Experiments have been conducted with both natural and town gas, and parameters such as emissions of NO{sub x}, CO and unburned fuel gas and thermal efficiency, etc, have been examined and are discussed. The results show that it is possible to reduce the NO{sub x} emissions up to 80% by a simple retro-fit installation, without decreasing the thermal efficiency of the cooking plate. The measured source strengths correspond to indoor NO{sub x} concentrations that are below or equal to the average outdoor concentration, implying that no additional detrimental health effects are probable. The drawback of the suggested installations is that the concentration of CO and in some cases also CH{sub 4} are increased in the flue gases

  20. Feed gas contaminant control in ion transport membrane systems

    Science.gov (United States)

    Carolan, Michael Francis [Allentown, PA; Minford, Eric [Laurys Station, PA; Waldron, William Emil [Whitehall, PA

    2009-07-07

    Ion transport membrane oxidation system comprising an enclosure having an interior and an interior surface, inlet piping having an internal surface and adapted to introduce a heated feed gas into the interior of the enclosure, and outlet piping adapted to withdraw a product gas from the interior of the enclosure; one or more planar ion transport membrane modules disposed in the interior of the enclosure, each membrane module comprising mixed metal oxide material; and a preheater adapted to heat a feed gas to provide the heated feed gas to the inlet piping, wherein the preheater comprises an interior surface. Any of the interior surfaces of the enclosure, the inlet piping, and the preheater may be lined with a copper-containing metal lining. Alternatively, any of the interior surfaces of the inlet piping and the preheater may be lined with a copper-containing metal lining and the enclosure may comprise copper.

  1. Oil and Gas Production Wastewater: Soil Contamination and Pollution Prevention

    Directory of Open Access Journals (Sweden)

    John Pichtel

    2016-01-01

    Full Text Available During oil and natural gas production, so-called “produced water” comprises the largest byproduct stream. In addition, many oil and gas operations are augmented via injection of hydraulic fracturing (HF fluids into the formation. Both produced water and HF fluids may contain hundreds of individual chemicals, some known to be detrimental to public health and the environment. Oil and gas production wastewater may serve a range of beneficial purposes, particularly in arid regions, if managed correctly. Numerous treatment technologies have been developed that allow for injection, discharge to the land surface, or beneficial reuse. Although many papers have addressed the effects of oil and gas production wastewater (OGPW on groundwater and surface water quality, significantly less information is available on the effects of these fluids on the soil resource. This review paper compiles fundamental information on numerous chemicals used and produced during oil and gas development and their effects on the soil environment. Additionally, pollution prevention technologies relating to OGPW are presented. An understanding of the effects of OGPW on soil chemical, physical, and biological properties can provide a foundation for effective remediation of OGPW-affected soils; additionally, sustainable reuse of oil and gas water for irrigation and industrial purposes may be enhanced.

  2. Microfabricated Gas Phase Chemical Analysis Systems

    Energy Technology Data Exchange (ETDEWEB)

    FRYE-MASON,GREGORY CHARLES; HELLER,EDWIN J.; HIETALA,VINCENT M.; KOTTENSTETTE,RICHARD; LEWIS,PATRICK R.; MANGINELL,RONALD P.; MATZKE,CAROLYN M.; WONG,CHUNGNIN C.

    1999-09-16

    A portable, autonomous, hand-held chemical laboratory ({micro}ChemLab{trademark}) is being developed for trace detection (ppb) of chemical warfare (CW) agents and explosives in real-world environments containing high concentrations of interfering compounds. Microfabrication is utilized to provide miniature, low-power components that are characterized by rapid, sensitive and selective response. Sensitivity and selectivity are enhanced using two parallel analysis channels, each containing the sequential connection of a front-end sample collector/concentrator, a gas chromatographic (GC) separator, and a surface acoustic wave (SAW) detector. Component design and fabrication and system performance are described.

  3. SVOC partitioning between the gas phase and settled dust indoors

    Science.gov (United States)

    Weschler, Charles J.; Nazaroff, William W.

    2010-09-01

    Semivolatile organic compounds (SVOCs) are a major class of indoor pollutants. Understanding SVOC partitioning between the gas phase and settled dust is important for characterizing the fate of these species indoors and the pathways by which humans are exposed to them. Such knowledge also helps in crafting measurement programs for epidemiological studies designed to probe potential associations between exposure to these compounds and adverse health effects. In this paper, we analyze published data from nineteen studies that cumulatively report measurements of dustborne and airborne SVOCs in more than a thousand buildings, mostly residences, in seven countries. In aggregate, measured median data are reported in these studies for 66 different SVOCs whose octanol-air partition coefficients ( Koa) span more than five orders of magnitude. We use these data to test a simple equilibrium model for estimating the partitioning of an SVOC between the gas phase and settled dust indoors. The results demonstrate, in central tendency, that a compound's octanol-air partition coefficient is a strong predictor of its abundance in settled dust relative to its gas phase concentration. Using median measured results for each SVOC in each study, dustborne mass fractions predicted using Koa and gas-phase concentrations correlate reasonably well with measured dustborne mass fractions ( R2 = 0.76). Combined with theoretical understanding of SVOC partitioning kinetics, the empirical evidence also suggests that for SVOCs with high Koa values, the mass fraction in settled dust may not have sufficient time to equilibrate with the gas phase concentration.

  4. Gas and particulate phase products from the ozonolysis of acenaphthylene

    Science.gov (United States)

    Riva, Matthieu; Healy, Robert M.; Tomaz, Sophie; Flaud, Pierre-Marie; Perraudin, Emilie; Wenger, John C.; Villenave, Eric

    2016-10-01

    Polycyclic aromatic hydrocarbons (PAHs) are recognized as important secondary organic aerosol (SOA) precursors in the urban atmosphere. In this work, the gas-phase ozonolysis of acenaphthylene was investigated in an atmospheric simulation chamber using a proton transfer reaction time-of-flight-mass spectrometer (PTR-TOF-MS) and an aerosol time-of-flight-mass spectrometer (ATOFMS) for on-line characterization of the oxidation products in the gas and particle phases, respectively. SOA samples were also collected on filters and analyzed by ultra performance liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS) and gas chromatography/electron impact ionization-mass spectrometry (GC/EI-MS). The major gas-phase products included a range of oxygenated naphthalene derivatives such as 1,8-naphthalic anhydride, naphthalene 1,8-dicarbaldehyde and naphthaldehyde, as well as a secondary ozonide. Possible reaction mechanisms are proposed for the formation of these products and favoured pathways have been suggested. Many of these products were also found in the particle phase along with a range of oligomeric compounds. The same range of gas and particle phase products was observed in the presence and absence of excess cyclohexane, an OH scavenger, indicating that OH radical production from the ozonolysis of acenaphthylene is negligible. SOA yields in the range 23-37% were determined and indicate that acenaphthylene ozonolysis may contribute to part of the SOA observed in urban areas.

  5. Post-flame gas-phase sulfation of potassium chloride

    DEFF Research Database (Denmark)

    Li, Bo; Sun, Zhiwei; Li, Zhongshan

    2013-01-01

    The sulfation of KCl during biomass combustion has implications for operation and emissions: it reduces the rates of deposition and corrosion, it increases the formation of aerosols, and it leads to higher concentrations of HCl and lower concentrations of SO2 in the gas phase. Rigorously homogene......The sulfation of KCl during biomass combustion has implications for operation and emissions: it reduces the rates of deposition and corrosion, it increases the formation of aerosols, and it leads to higher concentrations of HCl and lower concentrations of SO2 in the gas phase. Rigorously...... homogeneous systems are required to characterize the gas-phase formation of alkali sulfates. We have measured the temperature and gas-phase concentrations of KCl and HCl, and detected the presence of aerosols in the post-flame region of a range of hydrocarbon flames seeded with KCl, with and without...... and HCl and aerosols formed, most pronounced in flames with the lowest post-flame temperatures. This shows that KCl is sulfated in the gas phase to K2SO4, and this is followed by homogeneous nucleation of K2SO4 to form aerosols. Predictions from a kinetic model of the S/Cl/K chemistry agreed well...

  6. Gulf of Mexico offshore operations monitoring experiment (GOOMEX), Phase I: Sublethal responses to contaminant exposure - introduction and overview

    International Nuclear Information System (INIS)

    Kennicutt, M. C.; Montagna, P.; Roscigno, P. F.

    1996-01-01

    An overview of a three-phase study to evaluate the range of biological, biochemical and chemical methodologies to detect and assess chronic sublethal biological impacts in the vicinity of long-duration activities in the Gulf of Mexico associated with oil and gas exploration and production, was provided. The basic program comprises four activities stretching over a two-year period, and is designed to detect nearfield impacts and contaminant gradients extending out of each of three sites. Sampling design includes a radial pattern with stations at intervals up to 3000 meters distant from the platform. The design employs a dose-response model to test the hypothesis that biological, biochemical and chemical variations are due to platform-derived contaminants. Detailed analysis of the contaminants includes analysis of sediments, pore waters and biological tissue, and assessment of community health based on life history and reproduction studies. 57 refs., 9 tabs., 5 figs

  7. Phase space analysis of some interacting Chaplygin gas models

    Energy Technology Data Exchange (ETDEWEB)

    Khurshudyan, M. [Academy of Sciences of Armenia, Institute for Physical Research, Ashtarak (Armenia); Tomsk State University of Control Systems and Radioelectronics, Laboratory for Theoretical Cosmology, Tomsk (Russian Federation); Tomsk State Pedagogical University, Department of Theoretical Physics, Tomsk (Russian Federation); Myrzakulov, R. [Eurasian National University, Eurasian International Center for Theoretical Physics, Astana (Kazakhstan)

    2017-02-15

    In this paper we discuss a phase space analysis of various interacting Chaplygin gas models in general relativity. Linear and nonlinear sign changeable interactions are considered. For each case appropriate late time attractors of field equations are found. The Chaplygin gas is one of the dark fluids actively considered in modern cosmology due to the fact that it is a joint model of dark energy and dark matter. (orig.)

  8. Examination of background contamination levels for gas counting and AMS target preparation in Trondheim

    DEFF Research Database (Denmark)

    Gulliksen, S.; Thomsen, M.S.

    1992-01-01

    conventional gas proportional counting (GPC) system. We have also studied contamination levels of our target preparation for C-14 accelerator mass spectrometry (AMS) dating in Uppsala. A significant lower background is obtained for Icelandic double spar than for marbles, probably due to a crystal structure......The Radiological Dating Laboratory in Trondheim relatively often dates samples with ages >30 ka BP. Contaminated background materials are known to affect the accuracy of very old dates. We have found, by measurements of different materials, that such contamination is small when using our...... of the double spar that is more insensitive to contaminating processes. The background for combusted samples is at the same level as for samples of double spar, indicating that additional C-14 contamination due to combustion is negligible. Dates obtained on interstadial samples (T >30 ka BP) by both GPC and AMS...

  9. SVOC partitioning between the gas phase and settled dust indoors

    DEFF Research Database (Denmark)

    Weschler, Charles J.; Nazaroff, W. W.

    2010-01-01

    for estimating the partitioning of an SVOC between the gas phase and settled dust indoors. The results demonstrate, in central tendency, that a compound's octanol-air partition coefficient is a strong predictor of its abundance in settled dust relative to its gas phase concentration. Using median measured...... in crafting measurement programs for epidemiological studies designed to probe potential associations between exposure to these compounds and adverse health effects. In this paper, we analyze published data from nineteen studies that cumulatively report measurements of dustborne and airborne SVOCs in more...

  10. Reactive intermediates in the gas phase generation and monitoring

    CERN Document Server

    Setser, D W

    2013-01-01

    Reactive Intermediates in the Gas Phase: Generation and Monitoring covers methods for reactive intermediates in the gas phase. The book discusses the generation and measurement of atom and radical concentrations in flow systems; the high temperature flow tubes, generation and measurement of refractory species; and the electronically excited long-lived states of atoms and diatomic molecules in flow systems. The text also describes the production and detection of reactive species with lasers in static systems; the production of small positive ions in a mass spectrometer; and the discharge-excite

  11. The french experience concerning the contamination by inactive and radioactive impurities and the purification of the cover gas of LMFBRs

    International Nuclear Information System (INIS)

    Clerc, R.; Michaille, P.

    1986-09-01

    In this paper the authors describe, for Rapsodie, Phenix and Super Phenix reactors, the cover gas pipe works, the cover gas purification techniques and give for Rapsodie and Phenix the levels of contamination and the problems created by sodium aerosols

  12. Carbon contamination in scanning transmission electron microscopy and its impact on phase-plate applications.

    Science.gov (United States)

    Hettler, Simon; Dries, Manuel; Hermann, Peter; Obermair, Martin; Gerthsen, Dagmar; Malac, Marek

    2017-05-01

    We analyze electron-beam induced carbon contamination in a transmission electron microscope. The study is performed on thin films potentially suitable as phase plates for phase-contrast transmission electron microscopy. Electron energy-loss spectroscopy and phase-plate imaging is utilized to analyze the contamination. The deposited contamination layer is identified as a graphitic carbon layer which is not prone to electrostatic charging whereas a non-conductive underlying substrate charges. Several methods that inhibit contamination are evaluated and the impact of carbon contamination on phase-plate imaging is discussed. The findings are in general interesting for scanning transmission electron microscopy applications. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  13. Analytical study of solids-gas two phase flow

    International Nuclear Information System (INIS)

    Hosaka, Minoru

    1977-01-01

    Fundamental studies were made on the hydrodynamics of solids-gas two-phase suspension flow, in which very small solid particles are mixed in a gas flow to enhance the heat transfer characteristics of gas cooled high temperature reactors. Especially, the pressure drop due to friction and the density distribution of solid particles are theoretically analyzed. The friction pressure drop of two-phase flow was analyzed based on the analytical result of the single-phase friction pressure drop. The calculated values of solid/gas friction factor as a function of solid/gas mass loading are compared with experimental results. Comparisons are made for Various combinations of Reynolds number and particle size. As for the particle density distribution, some factors affecting the non-uniformity of distribution were considered. The minimum of energy dispersion was obtained with the variational principle. The suspension density of particles was obtained as a function of relative distance from wall and was compared with experimental results. It is concluded that the distribution is much affected by the particle size and that the smaller particles are apt to gather near the wall. (Aoki, K.)

  14. Uncatalyzed thermal gas phase aziridination of alkenes by organic ...

    Indian Academy of Sciences (India)

    Alkene aziridination by azides through uncatalyzed thermal gas phase routes has been studiedusing the DFT B3LYP/6-31G(d,p) method, where the possible role of discrete nitrene intermediates is emphasized.The thermal decomposition of azides is studied using the MP2/aug-cc-pVDZ strategy as well. The MP2(but not the ...

  15. Precursor-Less Coating of Nanoparticles in the Gas Phase

    NARCIS (Netherlands)

    Pfeiffer, T.V.; Kedia, P.; Messing, M.E.; Valvo, M.; Schmidt-Ott, A.

    2015-01-01

    This article introduces a continuous, gas-phase method for depositing thin metallic coatings onto (nano)particles using a type of physical vapor deposition (PVD) at ambient pressure and temperature. An aerosol of core particles is mixed with a metal vapor cloud formed by spark ablation by passing

  16. Nanoparticles-chemistry, new synthetic approaches, gas phase ...

    Indian Academy of Sciences (India)

    Abstract. In this paper, an overview of the synthesis, chemistry and applications of nanosystems carried out in our laboratory is presented. The discussion is divided into four sections, namely (a) chemistry of nanoparticles, (b) development of new synthetic approaches, (c) gas phase clusters and (d) device structures and ...

  17. Headspace solid-phase microextraction and gas chromatography ...

    African Journals Online (AJOL)

    Purpose: To extract and analyze the volatile components of Chrysanthemum morifolium Ramat. 'huaiju' by headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry. (GC–MS). Methods: Volatile components were extracted by HS-SPME and identified by GC–MS. The relative contents ...

  18. Nanoparticles-chemistry, new synthetic approaches, gas phase ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 65; Issue 4. Nanoparticles-chemistry ... in our laboratory is presented. The discussion is divided into four sections, namely (a) chemistry of nanoparticles, (b) development of new synthetic approaches, (c) gas phase clusters and (d) device structures and applications.

  19. Gas phase and solution structures of 1-methoxyallenyllithium.

    Science.gov (United States)

    Dixon, Darryl D; Tius, Marcus A; Pratt, Lawrence M

    2009-08-21

    A combined computational and (13)C NMR study was used to determine the solution structures of 1-methoxyallenyllithium. The gas phase calculations indicated that this species is aggregated as a hexamer. The NMR spectra in THF solution, together with the calculated aggregation energies and chemical shifts, are consistent with a dimer-tetramer equilibrium.

  20. Headspace solid-phase microextraction and gas chromatography ...

    African Journals Online (AJOL)

    Purpose: To extract and analyze the volatile components of Chrysanthemum morifolium Ramat. 'huaiju' by headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC–MS). Methods: Volatile components were extracted by HS-SPME and identified by GC–MS. The relative contents ...

  1. Gas phase toluene isopropylation over high silica mordenite

    Indian Academy of Sciences (India)

    Mordenite (HM) catalysts with three different Si/Al ratios were compared for their activity and selectivities in gas phase toluene isopropylation with isopropanol. Catalyst with Si/Al ratio 44.9 offered better cumene selectivity, hence, it was chosen for detailed kinetic investigations. The influence of various process parameters ...

  2. Gas-Phase IR Spectroscopy of Deprotonated Amino Acids

    NARCIS (Netherlands)

    Oomens, J.; Steill, J. D.; Redlich, B.

    2009-01-01

    Gas-phase infrared multiple photon dissociation (IRMPD) spectra have been recorded for the conjugate bases of a series of amino acids (Asp, Cys, Glu, Phe, Set, Trp, Tyr). The spectra are dominated by strong symmetric and antisymmetric carboxylate stretching modes around 1300 and 1600 cm(-1),

  3. Infrared spectroscopy of ionized corannulene in the gas phase

    NARCIS (Netherlands)

    Alvaro Galué, H.; Rice, C.A.; Steill, J.D.; Oomens, J.

    2011-01-01

    The gas-phase infrared spectra of radical cationic and protonated corannulene were recorded by infrared multiple-photon dissociation (IRMPD) spectroscopy using the IR free electron laser for infrared experiments. Electrospray ionization was used to generate protonated corannulene and an IRMPD

  4. Capillary gas chromatography for the determination of halogenated micro-contaminants

    NARCIS (Netherlands)

    Boer, de J.

    1999-01-01

    Capillary gas chromatography (GC) is a very useful technique for the determination of complex mixtures of halogenated contaminants. Initially, this technique has shown its merits for the determination of polychlorinated biphenyls and organochlorine pesticides. In addition, it has also broken new

  5. Plasma cleaning of beamline optical components: Contamination and gas composition effects

    International Nuclear Information System (INIS)

    Rosenberg, R.A.; Smith, J.A.; Wallace, D.J.

    1992-01-01

    We have initiated a program to study the impact of gas composition on the carbon removal rate during plasma cleaning of optical components, and of possible contamination due to the plasma processing. The measurements were performed in a test chamber designed to simulate the geometry of the grating/Codling mirror section of a Grasshopper monochromator. Removal rates were determined for a direct-current (dc) (Al electrode) discharge using a quartz crystal microbalance coated with polymethylmethacrylate, located at the position of the grating. Auger electron spectroscopy analysis of strateg- ically located, gold-coated stainless steel samples was employed to determine contamination. The relative removal rates of the gases studied were 3% C 2 F 6 /O 2 much-gt O 2 +H 2 O>O 2 ∼N 2 O>H 2 >N 2 . Although the C 2 F 6 /O 2 gas mixture showed a 20 times greater removal rate than its nearest competitor, it also caused significant contamination to occur. Contamination studies were performed for both dc and radio-frequency (rf) discharges. For the dc discharge we found that great care must be taken in order to avoid Al contamination; for the rf discharge, significant Fe contamination was observed

  6. Reactions of newly formed fission products in the gas phase

    International Nuclear Information System (INIS)

    Strickert, R.G.

    1976-01-01

    A dynamic gas-flow system was constructed which stopped fission products in the gas phase and rapidly separated (in less than 2 sec) volatile compounds from non-volatile ones. The filter assembly designed and used was shown to stop essentially all non-volatile fission products. Between 5 percent and 20 percent of tellurium fission-product isotopes reacted with several hydrocarbon gases to form volatile compounds, which passed through the filter. With carbon monoxide gas, volatile tellurium compound(s) (probably TeCO) were also formed with similar efficiencies. The upper limits for the yields of volatile compounds formed between CO and tin and antimony fission products were shown to be less than 0.3 percent, so tellurium nuclides, not their precursors, reacted with CO. It was found that CO reacted preferentially with independently produced tellurium atoms; the reaction efficiency of beta-produced atoms was only 27 +- 3 percent of that of the independently formed atoms. The selectivity, which was independent of the over-all reaction efficiency, was shown to be due to reaction of independently formed atoms in the gas phase. The gas phase reactions are believed to occur mainly at thermal energies because of the independence of the yield upon argon moderator mole-fraction (up to 80 percent). It was shown in some experiments that about one-half of the TeCO decomposed in passing through a filter and that an appreciable fraction (approximately 20 percent) of the tellurium atoms deposited on the filter reacted agin with CO. Other tellurium atoms on the filter surface (those formed by beta decay and those formed independently but not reacting in the gas phase) also reacted with CO, but probably somewhat less efficiently than atoms formed by TeCO decomposition. No evidence was found for formation of TeCO as a direct result of beta-decay

  7. Highly Selective Continuous Gas-Phase Methoxycarbonylation of Ethylene with Supported Ionic Liquid Phase (SILP) Catalysts

    DEFF Research Database (Denmark)

    Khokarale, Santosh Govind; Garcia Suárez, Eduardo José; Fehrmann, Rasmus

    2017-01-01

    Supported ionic liquid phase (SILP) technology was applied for the first time to the Pd-catalyzed continuous, gas-phase methoxycarbonylation of ethylene to selectively produce methyl propanoate (MP) in high yields. The influence of catalyst and reaction parameters such as, for example, ionic liquid...

  8. Continuous gas-phase hydroformylation of 1-butene using supported ionic liquid phase (SILP) catalysts

    DEFF Research Database (Denmark)

    Haumann, Marco; Dentler, Katharina; Joni, Joni

    2007-01-01

    The concept of supported ionic liquid phase (SILP) catalysis has been extended to 1-butene hydroformylation. A rhodium-sulfoxantphos complex was dissolved in [BMIM][n-C8H17OSO3] and this solution was highly dispersed on silica. Continuous gas-phase experiments in a fixed-bed reactor revealed...

  9. SILP catalysis in gas-phase hydroformylation and carbonylation

    Energy Technology Data Exchange (ETDEWEB)

    Riisager, A.; Fehrmann, R. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemistry; Haumann, M.; Wasserscheid, P. [Univ. Erlangen-Nuernberg (Germany). Lehrstuhl fuer Chemische Reaktionstechnik

    2006-07-01

    Supported ionic liquid phase (SILP) catalysts are new materials consisting of an ionic liquid-metal catalyst solution highly dispersed on a porous support. The use of a non-volatile, ionic liquid catalyst phase in SILP catalysts results in a stable heterogeneous-type material with selectivity and efficiency like homogeneous catalysts. The silica-supported SILP Rh-bisphosphine hydroformylation catalyst exhibited good activities and excellent selectivities in gas phase hydroformylation with stability exceeding 700 hours time-on-stream. Spectroscopic and kinetic data confirmed the homogeneous nature of the catalyst. In the Rh- SILP catalysed carbonylation of methanol the formation of undesired by-products could be suppressed by variation of residence time and gas pressure. (orig.)

  10. Characterization of the vadose zone above a shallow aquifer contaminated with gas condensate hydrocarbons

    International Nuclear Information System (INIS)

    Sublette, K.; Duncan, K.; Thoma, G.; Todd, T.

    2002-01-01

    A gas production site in the Denver Basin near Ft. Lupton, Colorado has leaked gas condensate hydrocarbons from an underground concrete tank used to store produced water. The leak has contaminated a shallow aquifer. Although the source of pollution has been removed, a plume of hydrocarbon contamination still remains for nearly 46 m from the original source. An extensive monitoring program was conducted in 1993 of the groundwater and saturated sediments. The objective was to determine if intrinsic aerobic or anaerobic bioremediation of hydrocarbons occurred at the site at a rate that would support remediation. Geochemical indicators of hydrogen biodegradation by microorganisms in the saturated zone included oxygen depletion, increased alkalinity, sulfate depletion, methane production and Fe2+ production associated with hydrogen contamination. The presence of sulfate-reducing bacteria and methanogens was also much higher in the contaminated sediments. Degraded hydrocarbon metabolites were found in contaminated groundwater. An extensive characterization of the vadose zone was conducted in which the vadose zone was sample in increments of 15 cm from the surface to the water table at contaminated and non contaminated sites. The samples were tested for individual C3+ hydrocarbons, methane, CO2, total organic carbon, total inorganic carbon, and total petroleum hydrocarbons. The vadose zone consisted of an active and aerobic bioreactor fueled by condensate hydrocarbons transported into the unsaturated zone by evaporation of hydrocarbons at the water table. It was concluded that the unsaturated zone makes an important contribution to the natural attenuation of gas condensate hydrocarbons in the area. 17 refs., 2 tabs., 28 figs

  11. Comparison of tree coring and soil gas sampling for screening of contaminated sites

    DEFF Research Database (Denmark)

    Nielsen, Mette Algreen; Stalder, Marcel; Riis, Charlotte

    when (with respect to compounds, soil properties, and locations) one method is preferred over the other. Fields sampling was performed at European sites contaminated with fuel components or chlorinated solvents from former site activities (industrial production, gas stations, air base or gas plant......Site characterization is often time consuming and a financial burden for the site owners, which raises a demand for rapid and inexpensive (pre)screening methods. Phytoscreening by tree coring has shown to be a useful tool to detect subsurface contamination, especially of chlorinated solvents....... However the application and dissemination of the method is still limited. On the other hand, soil gas sampling for mapping of volatile organic compounds in the subsurface is a common and commercially applied method. Both methods are semi-quantitative, low-invasive and inexpensive, which makes them...

  12. Gas-liquid two-phase flows in double inlet cyclones for natural gas separation

    DEFF Research Database (Denmark)

    Yang, Yan; Wang, Shuli; Wen, Chuang

    2017-01-01

    The gas-liquid two-phase flow within a double inlet cyclone for natural gasseparation was numerically simulated using the discrete phase model. The numericalapproach was validated with the experimental data, and the comparison resultsagreed well with each other. The simulation results showed...... that the strong swirlingflow produced a high centrifugal force to remove the particles from the gas mixture.The larger particles moved downward on the internal surface and were removeddue to the outer vortex near the wall. Most of the tiny particles went into the innervortex zones and escaped from the up...

  13. Preconceptual design of the gas-phase decontamination demonstration cart

    International Nuclear Information System (INIS)

    Munday, E.B.

    1993-12-01

    Removal of uranium deposits from the interior surfaces of gaseous diffusion equipment will be a major portion of the overall multibillion dollar effort to decontaminate and decommission the gaseous diffusion plants. Long-term low-temperature (LTLT) gas-phase decontamination is being developed at the K-25 Site as an in situ decontamination process that is expected to significantly lower the decontamination costs, reduce worker exposure to radioactive materials, and reduce safeguard concerns. This report documents the preconceptual design of the process equipment that is necessary to conduct a full-scale demonstration of the LTLT method in accordance with the process steps listed above. The process equipment and method proposed in this report are not intended to represent a full-scale production campaign design and operation, since the gas evacuation, gas charging, and off-gas handling systems that would be cost effective in a production campaign are not cost effective for a first-time demonstration. However, the design presented here is expected to be applicable to special decontamination projects beyond the demonstration, which could include the Deposit Recovery Program. The equipment will therefore be sized to a 200 ft size 1 converter (plus a substantial conservative design margin), which is the largest item of interest for gas phase decontamination in the Deposit Recovery Program. The decontamination equipment will allow recovery of the UF 6 , which is generated from the reaction of ClF 3 with the uranium deposits, by use of NaF traps

  14. High-Performance Contaminant Monitor for Spacecraft, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The Vision for Space Exploration demands increasing reliance on real-time trace gas monitors onboard spacecraft. Present grab samples and badges will be inadequate...

  15. Contaminants migration in the soil: the influence of transfer between the mobile and stationary phases

    International Nuclear Information System (INIS)

    Moreira, R.M.; Sabino, C.S.V.; Macedo, W.A.

    1996-01-01

    Three transport mechanisms control the contaminant migration in saturated soils: advection, diffusion and interchanges between liquid and solid phases. These interchanges define the retention by the soil and the contaminant delay related to the liquid phase flow. Therefore, the knowledge of the adsorption/desorption characteristics of the solute in solid surfaces is fundamental for the evaluation of toxic agent releases to the compartment soil. This communication reports the study which is being performed by the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) in this area, particularly with cesium and mercury by using X-ray absorption spectroscopy for contaminants migration

  16. Probing the Gas-Phase Dynamics of Graphene Chemical Vapour Deposition using in-situ UV Absorption Spectroscopy.

    Science.gov (United States)

    Shivayogimath, Abhay; Mackenzie, David; Luo, Birong; Hansen, Ole; Bøggild, Peter; Booth, Timothy J

    2017-07-21

    The processes governing multilayer nucleation in the chemical vapour deposition (CVD) of graphene are important for obtaining high-quality monolayer sheets, but remain poorly understood. Here we show that higher-order carbon species in the gas-phase play a major role in multilayer nucleation, through the use of in-situ ultraviolet (UV) absorption spectroscopy. These species are the volatilized products of reactions between hydrogen and carbon contaminants that have backstreamed into the reaction chamber from downstream system components. Consequently, we observe a dramatic suppression of multilayer nucleation when backstreaming is suppressed. These results point to an important and previously undescribed mechanism for multilayer nucleation, wherein higher-order gas-phase carbon species play an integral role. Our work highlights the importance of gas-phase dynamics in understanding the overall mechanism of graphene growth.

  17. Gas-phase photocatalysis in μ-reactors

    DEFF Research Database (Denmark)

    Vesborg, Peter Christian Kjærgaard; Olsen, Jakob Lind; Henriksen, Toke Riishøj

    2010-01-01

    Gas-phase photocatalysis experiments may benefit from the high sensitivity and good time response in product detection offered by μ-reactors. We demonstrate this by carrying out CO oxidation and methanol oxidation over commercial TiO2 photocatalysts in our recently developed high-sensitivity reac......Gas-phase photocatalysis experiments may benefit from the high sensitivity and good time response in product detection offered by μ-reactors. We demonstrate this by carrying out CO oxidation and methanol oxidation over commercial TiO2 photocatalysts in our recently developed high......-sensitivity reactors. We demonstrate that the system exhibits great versatility in terms of photocatalyst, illumination source and target reaction....

  18. Preconcentration in gas or liquid phases using adsorbent thin films

    Directory of Open Access Journals (Sweden)

    Antonio Pereira Nascimento Filho

    2006-03-01

    Full Text Available The possibility of preconcentration on microchannels for organic compounds in gas or liquid phases was evaluated. Microstructures with different geometries were mechanically machined using poly(methyl methacrylate - PMMA as substrates and some cavities were covered with cellulose. The surfaces of the microchannels were modified by plasma deposition of hydrophilic or hydrophobic films using 2-propanol and hexamethyldisilazane (HMDS, respectively. Double layers of HMDS + 2-propanol were also used. Adsorption characterization was made by Quartz Crystal Measurements (QCM technique using reactants in a large polarity range that showed the adsorption ability of the structures depends more on the films used than on the capillary phenomena. Cellulose modified by double layer film showed a high retention capacity for all gaseous compounds tested. However, structures without plasma deposition showed low retention capacity. Microchannels modified with double layers or 2-propanol plasma films showed higher retention than non-modified ones on gas or liquid phase.

  19. Two-phase dynamics of gas-heated steam generators

    International Nuclear Information System (INIS)

    Schittke, H.J.

    1977-01-01

    The dynamic behavior of a once-through steam generator plant operating in the secondary loop of a gas-cooled high-temperature reactor is considered. The mathematical model used for the description of the thermohydraulics of the problem comprises not only the dynamic behavior of the primary heating gas flow and the tube wall temperatures but especially the effects of pressure dynamics in the secondary fluid and the relevant two-phase flow phenomena: using an additional momentum balance equation for the dynamics of the slip velocity it is shown that the analytical computation of the slip velocity it is shown that the analytical computation of slip and two-phase pressure drop effects from the model equations is possible without the use of external correlations. Based on this mathematical model a generally applicable computer model is used to simulate the dynamic response of a given system

  20. Gas Phase Hydrogenation of Levulinic Acid to gamma-Valerolactone

    NARCIS (Netherlands)

    Bonrath, Werner; Castelijns, Anna Maria Cornelia Francisca; de Vries, Johannes Gerardus; Guit, Rudolf Philippus Maria; Schuetz, Jan; Sereinig, Natascha; Vaessen, Henricus Wilhelmus Leonardus Marie

    The gas phase hydrogenation of levulinic acid to gamma-valerolactone over copper and ruthenium based catalysts in a continuous fixed-bed reactor system was investigated. Among the catalysts a copper oxide based one [50-75 % CuO, 20-25 % SiO2, 1-5 % graphite, 0.1-1 % CuCO3/Cu(OH)(2)] gave

  1. The gas chimney formation during the steam explosion premixing phase

    International Nuclear Information System (INIS)

    Leskovar, M.

    2001-01-01

    The crucial part in isothermal premixing experiment simulation is the correct prediction of the gas chimney, which forms when the spheres penetrate into water. The first simulation results with the developed original combined multiphase model showed that the gas chimney starts to close at the wrong place at the top of the chimney and not in the middle, like it was observed in the experiments. To find the physical explanation for this identified weakness of our numerical model a comprehensive parametric analysis (mesh size, initial water-air surface thickness, water density, momentum coupling starting position) has been performed. It was established that the reason for the unphysical gas chimney closing at the top could be the gradual air-water density transition in the experiment model, since there is due to the finite differences description always a transition layer with intermediate phases density over the pure water phase. It was shown that this difference between our numerical model and the experiment can be somewhat compensated if the spheres interfacial drag coefficient at the upmost mesh plane of the unphysical air-water transition layer is artificially risen. On this way a more correct gas chimney formation can be obtained.(author)

  2. Theory of Gas Injection: Interaction of Phase Behavior and Flow

    Science.gov (United States)

    Dindoruk, B.

    2015-12-01

    The theory of gas injection processes is a central element required to understand how components move and partition in the reservoir as one fluid is displacing another (i.e., gas is displacing oil). There is significant amount of work done in the area of interaction of phase-behavior and flow in multiphase flow conditions. We would like to present how the theory of gas injection is used in the industry to understand/design reservoir processes in various ways. The tools that are developed for the theory of gas injection originates from the fractional flow theory, as the first solution proposed by Buckley-Leveret in 1940's, for water displacing oil in porous media. After 1960's more and more complex/coupled equations were solved using the initial concept(s) developed by Buckley-Leverett, and then Welge et al. and others. However, the systematic use of the fractional flow theory for coupled set of equations that involves phase relationships (EOS) and phase appearance and disappearance was mainly due to the theory developed by Helfferich in early 80's (in petroleum literature) using method of characteristics primarily for gas injection process and later on by the systematic work done by Orr and his co-researchers during the last two decades. In this talk, we will present various cases that use and extend the theory developed by Helfferich and others (Orr et al., Lake et al. etc.). The review of various injection systems reveals that displacement in porous media has commonalities that can be represented with a unified theory for a class of problems originating from the theory of gas injection (which is in a way generalized Buckley-Leverett problem). The outcome of these solutions can be used for (and are not limited to): 1) Benchmark solutions for reservoir simulators (to quantify numerical dispersion, test numerical algorithms) 2) Streamline simulators 3) Design of laboratory experiments and their use (to invert the results) 4) Conceptual learning and to investigate

  3. Multi-phase flow modeling of soil contamination and soil remediation

    NARCIS (Netherlands)

    Dijke, van M.I.J.

    1997-01-01


    In this thesis multi-phase flow models are used to study the flow behavior of liquid contaminants in aquifers and of gases that are injected below the groundwater table for remediation purposes. Considered problems are redistribution of a lens of light nonaqueous phase

  4. Ab initio study of gas phase and water-assisted tautomerization of ...

    Indian Academy of Sciences (India)

    WINTEC

    Ab initio study of gas phase and water-assisted tautomerization of maleimide and formamide. 623. Figure 4. Keto to enol conversion of (a) maleimide and (b) formamide in gas phase. (c) maleimide and (d) forma- mide with water.

  5. Statistical parameter characteristics of gas-phase fluctuations for gas-liquid intermittent flow

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, G.; Monji, H.; Takaguchi, M. [Univ. of Tsukuba (Japan)

    1995-09-01

    This study deals with theoretical analysis on the general behaviour of statistical parameters of gas-phase fluctuations and comparison of statistical parameter characteristics for the real void fraction fluctuations measured with those for the wave form modified the real fluctuations. In order to investigate the details of the relation between the behavior of the statistical parameters in real intermittent flow and analytical results obtained from information on the real flow, the distributions of statistical parameters for general fundamental wave form of gas-phase fluctuations are discussed in detail. By modifying the real gas-phase fluctuations to a trapezoidaly wave, the experimental results can be directly compared with the analytical results. The analytical results for intermittent flow show that the wave form parameter, and the total amplitude of void fraction fluctuations, affects strongly on the statistical parameter characteristics. The comparison with experiment using nitrogen gas-water intermittent flow suggests that the parameters of skewness and excess may be better as indicators of flow pattern. That is, the macroscopic nature of intermittent flow can be grasped by the skewness and the excess, and the detailed flow structure may be described by the mean and the standard deviation.

  6. Point source attribution of ambient contamination events near unconventional oil and gas development.

    Science.gov (United States)

    Hildenbrand, Zacariah L; Mach, Phillip M; McBride, Ethan M; Dorreyatim, M Navid; Taylor, Josh T; Carlton, Doug D; Meik, Jesse M; Fontenot, Brian E; Wright, Kenneth C; Schug, Kevin A; Verbeck, Guido F

    2016-12-15

    We present an analysis of ambient benzene, toluene, and xylene isomers in the Eagle Ford shale region of southern Texas. In situ air quality measurements using membrane inlet mobile mass spectrometry revealed ambient benzene and toluene concentrations as high as 1000 and 5000 parts-per-billion, respectively, originating from specific sub-processes on unconventional oil and gas well pad sites. The detection of highly variant contamination events attributable to natural gas flaring units, condensate tanks, compressor units, and hydrogen sulfide scavengers indicates that mechanical inefficiencies, and not necessarily the inherent nature of the extraction process as a whole, result in the release of these compounds into the environment. This awareness of ongoing contamination events contributes to an enhanced knowledge of ambient volatile organic compounds on a regional scale. While these reconnaissance measurements on their own do not fully characterize the fluctuations of ambient BTEX concentrations that likely exist in the atmosphere of the Eagle Ford Shale region, they do suggest that contamination events from unconventional oil and gas development can be monitored, controlled, and reduced. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Fundamental thermochemical properties of amino acids: gas-phase and aqueous acidities and gas-phase heats of formation.

    Science.gov (United States)

    Stover, Michele L; Jackson, Virgil E; Matus, Myrna H; Adams, Margaret A; Cassady, Carolyn J; Dixon, David A

    2012-03-08

    The gas-phase acidities of the 20 L-amino acids have been predicted at the composite G3(MP2) level. A broad range of structures of the neutral and anion were studied to determine the lowest energy conformer. Excellent agreement is found with the available experimental gas-phase deprotonation enthalpies, and the calculated values are within experimental error. We predict that tyrosine is deprotonated at the CO(2)H site. Cysteine is predicted to be deprotonated at the SH but the proton on the CO(2)H is shared with the S(-) site. Self-consistent reaction field (SCRF) calculations with the COSMO parametrization were used to predict the pK(a)'s of the non-zwitterion form in aqueous solution. The differences in the non-zwitterion pK(a) values were used to estimate the free energy difference between the zwitterion and nonzwitterion forms in solution. The heats of formation of the neutral compounds were calculated from atomization energies and isodesmic reactions to provide the first reliable set of these values in the gas phase. Further calculations were performed on five rare amino acids to predict their heats of formation, acidities, and pK(a) values.

  8. Delineation of ground-water contamination using soil-gas analyses near Jackson, Tennessee

    Science.gov (United States)

    Lee, R.W.

    1991-01-01

    An investigation of the ground-water resources near Jackson, West Tennessee, was conducted during 1988-89. The study included determination of the occurrence of contaminants in the shallow aquifer using soil-gas analyses in the unsaturated zone. Between 1980 and 1988, an underground fuel-storage tank leaked about 3,000 gallons of unleaded fuel to the water table about 4 feet below land surface. A survey of soil gas using a gas chromatograph equipped with a photoionization detector showed concentrations of volatile organic compounds greater than IO, 000 parts per million near the leak These compounds were detected in an area about 240 feet long and 110 feet wide extending west from the point source. The chromatograms provided two distinct 'fingerprints' of volatile organic compounds. The first revealed the presence of benzene, toluene, andxylenes, which are constituents of unleaded fuel, in addition to other volatile compounds, in soil gas in the area near the leak The second did not reveal any detectable benzene, toluene, or xylenes in the soil-gas samples, but showed the presence of other unidentified volatile organic compounds in soil gas north of the storage tank. The distribution of total concentrations of volatile organic compounds in the unsaturated zone indicated that a second plume about 200 feet long and 90 feet wide was present about 100 feet north of the storage tank The second plume could have been the result of previous activities at this site during the 1950's or earlier. Activities at the site are believed to have included storage of solvents used at the nearby railyard and flushing of tanks containing tar onto a gravel-covered parking area. The delineation of these plumes has shown that soil-gas analyses can be a useful technique for identifying areas of contamination with volatile organic compounds in shallow water-table aquifers and may have broad applications in similar situations where the water table is relatively close to the surface.

  9. Effects of Surfactant Contamination on the Next Generation Gas Trap for the ISS Internal Thermal Control System

    Science.gov (United States)

    Leimkuehler, Thomas O.; Lukens, Clark; Reeves, Daniel R.; Holt, James M.

    2004-01-01

    The current dual-membrane gas trap is designed to remove non-condensed gas bubbles from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). To date it has successfully served its purpose of preventing gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pump. However, contamination in the ITCS coolant has adversely affected the gas venting rate and lifetime of the gas trap, warranting a development effort for a next-generation gas trap. Previous testing has shown that a hydrophobic-only design is capable of performing even better than the current dual-membrane design for both steady-state gas removal and gas slug removal in clean deionized water. This paper presents results of testing to evaluate the effects of surfactant contamination on the steady-state performance of the hydrophobic-only design.

  10. DSMC Convergence for Microscale Gas-Phase Heat Conduction

    Science.gov (United States)

    Rader, D. J.; Gallis, M. A.; Torczynski, J. R.

    2004-11-01

    The convergence of Bird's Direct Simulation Monte Carlo (DSMC) method is investigated for gas-phase heat conduction at typical microscale conditions. A hard-sphere gas is confined between two fully accommodating walls of unequal temperature. Simulations are performed for small system and local Knudsen numbers, so continuum flow exists outside the Knudsen layers. The ratio of the DSMC thermal conductivity to the Chapman-Enskog value in the central region is determined for over 200 combinations of time step, cell size, and number of computational molecules per cell. In the limit of vanishing error, this ratio approaches 1.000 to within the correlation uncertainty. In the limit of infinite computational molecules per cell, the difference from unity depends quadratically on time step and cell size as these quantities become small. The coefficients of these quadratic terms are in good agreement with Green-Kubo values found by Hadjiconstantinou, Garcia, and co-workers. These results demonstrate that DSMC can accurately simulate microscale gas-phase heat conduction. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  11. Unimolecular Gas-Phase Thermolysis of Ethyl Acetate

    DEFF Research Database (Denmark)

    Egsgaard, Helge; Carlsen, Lars

    1983-01-01

    The unimolecular gas-phase thermolysis of ethyl acetate has been investigated by the Flash-Vacuum-Thermolysis/Field-Ionization Mass Spectrometry (FVT/FI-MS) method in combination with Collision Activation (CA) mass spectrometry at 1253K. Two predominant reactions are observed: elimination...... of ethylene affording acetic acid, the latter to some extent consecutively yielding ketene, and intramolecular oxygen to oxygen ethyl group migration. Additionally minor amounts of acetaldehyde is formed. The mechanistic aspects are discussed based on 18O and 18O/ 13C labelling....

  12. Production Decline Analysis for Two-Phase Flow in Multifractured Horizontal Well in Shale Gas Reservoirs

    OpenAIRE

    Xie, Wei-Yang; Li, Xiao-Ping; Zhang, Lie-Hui; Tan, Xiao-Hua; Wang, Jun-Chao; Wang, Hai-Tao

    2015-01-01

    After multistage fracturing, the flowback of fracturing fluid will cause two-phase flow through hydraulic fractures in shale gas reservoirs. With the consideration of two-phase flow and desorbed gas transient diffusion in shale gas reservoirs, a two-phase transient flow model of multistage fractured horizontal well in shale gas reservoirs was created. Accurate solution to this flow model is obtained by the use of source function theory, Laplace transform, three-dimensional eigenvalue method, ...

  13. Multi-residue analysis of legacy POPs and emerging organic contaminants in Singapore's coastal waters using gas chromatography-triple quadrupole tandem mass spectrometry.

    Science.gov (United States)

    Zhang, Hui; Bayen, Stéphane; Kelly, Barry C

    2015-08-01

    A gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) based method was developed for determination of 86 hydrophobic organic compounds in seawater. Solid-phase extraction (SPE) was employed for sequestration of target analytes in the dissolved phase. Ultrasound assisted extraction (UAE) and florisil chromatography were utilized for determination of concentrations in suspended sediments (particulate phase). The target compounds included multi-class hydrophobic contaminants with a wide range of physical-chemical properties. This list includes several polycyclic and nitro-aromatic musks, brominated and chlorinated flame retardants, methyl triclosan, chlorobenzenes, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Spiked MilliQ water and seawater samples were used to evaluate the method performance. Analyte recoveries were generally good, with the exception of some of the more volatile target analytes (chlorobenzenes and bromobenzenes). The method is very sensitive, with method detection limits typically in the low parts per quadrillion (ppq) range. Analysis of 51 field-collected seawater samples (dissolved and particulate-bound phases) from four distinct coastal sites around Singapore showed trace detection of several polychlorinated biphenyl congeners and other legacy POPs, as well as several current-use emerging organic contaminants (EOCs). Polycyclic and nitro-aromatic musks, bromobenzenes, dechlorane plus isomers (syn-DP, anti-DP) and methyl triclosan were frequently detected at appreciable levels (2-20,000pgL(-1)). The observed concentrations of the monitored contaminants in Singapore's marine environment were generally comparable to previously reported levels in other coastal marine systems. To our knowledge, these are the first measurements of these emerging contaminants of concern in Singapore or Southeast Asia. The developed method may prove beneficial for future environmental monitoring of hydrophobic organic contaminants

  14. Polaronic exciton behavior in gas-phase water

    Science.gov (United States)

    Udal'tsov, Alexander V.

    2018-03-01

    Features of the absorption spectrum of gas-phase water in the energy range 7-10 eV have been considered applying polaronic exciton theory. The interaction of the incident photon generating polaronic exciton in water is described taking into account angular momentum of the electron so that polaronic exciton radii have been estimated in dependence on spin-orbit coupling under proton sharing. The suggested approach admits an estimate of kinetic and rotation energies of the polaronic exciton. As a result sixteen steps of half Compton wavelength, λC/2 = h/(2mec) changing polaronic exciton radius were found consistent with local maxima and shoulders in the spectrum. Thus, the absorption of gas-phase water in the energy range 8.5-10 eV has been interpreted in terms of polaronic exciton rotation mainly coupled with the proton sharing. The incident photon interaction with water is also considered in terms of Compton interaction, when the rotation energy plays a role like the energy loss of the incident photon under Compton scattering. The found symmetry and the other evidence allowed to conclude about polaronic exciton migration under the interaction angle 90°.

  15. Closed-cage tungsten oxide clusters in the gas phase.

    Science.gov (United States)

    Singh, D M David Jeba; Pradeep, T; Thirumoorthy, Krishnan; Balasubramanian, Krishnan

    2010-05-06

    During the course of a study on the clustering of W-Se and W-S mixtures in the gas phase using laser desorption ionization (LDI) mass spectrometry, we observed several anionic W-O clusters. Three distinct species, W(6)O(19)(-), W(13)O(29)(-), and W(14)O(32)(-), stand out as intense peaks in the regular mass spectral pattern of tungsten oxide clusters suggesting unusual stabilities for them. Moreover, these clusters do not fragment in the postsource decay analysis. While trying to understand the precursor material, which produced these clusters, we found the presence of nanoscale forms of tungsten oxide. The structure and thermodynamic parameters of tungsten clusters have been explored using relativistic quantum chemical methods. Our computed results of atomization energy are consistent with the observed LDI mass spectra. The computational results suggest that the clusters observed have closed-cage structure. These distinct W(13) and W(14) clusters were observed for the first time in the gas phase.

  16. Potential Air Contamination During CO2 Angiography Using a Hand-Held Syringe: Theoretical Considerations and Gas Chromatography

    International Nuclear Information System (INIS)

    Cho, David R.; Cho, Kyung J.; Hawkins, Irvin F.

    2006-01-01

    Purpose. To assess air contamination in the hand-held syringes currently used for CO 2 delivery and to determine whether there is an association between their position and the rate of air contamination. Methods. Assessment of air contamination in the syringe (20 ml) included theoretical modeling, mathematical calculation, and gas chromatography (GC). The model was used with Fick's first law to calculate the diffusion of CO 2 and the amount of air contamination. For GC studies, the syringes were placed in the upright, horizontal, and inverted positions and gas samples were obtained after 5, 10, 20, 30, and 60 min. All trials with each position for each sampling time were performed five times. Results. The amounts of air contamination with time calculated mathematically were 5-10% less than those of GC. With the diffusivity of air-CO 2 at 0.1599 cm 2 /sec (9.594 cm 2 /min), air contamination was calculated to be 60% at 60 min. With GC air contamination was 13% at 5 min, 31% at 20 min, 43% at 30 min, and 68% at 60 min. There was no difference in air contamination between the different syringe positions. Conclusion. Air contamination occurs in hand-held syringes filled with CO 2 when they are open to the ambient air. The amounts of air contamination over time are similar among syringes placed in the upright, horizontal, and inverted positions

  17. Risk assessment of gas oil and kerosene contamination on some properties of silty clay soil.

    Science.gov (United States)

    Fallah, M; Shabanpor, M; Zakerinia, M; Ebrahimi, S

    2015-07-01

    Soil and ground water resource pollution by petroleum compounds and chemical solvents has multiple negative environmental impacts. The aim of this research was to investigate the impacts of kerosene and gas oil pollutants on some physical and chemical properties, breakthrough curve (BTC), and water retention curve (SWRC) of silty clay soil during a 3-month period. Therefore, some water-saturated soils were artificially contaminated in the pulse condition inside some glassy cylinders by applying half and one pore volume of these pollutants, and then parametric investigations of the SWRC were performed using RETC software for Van Genukhten and Brooks-Corey equations in the various suctions and the soil properties were determined before and after pollution during 3 months. The results showed that gas oil and kerosene had a slight effect on soil pH and caused the cumulative enhancement in the soil respiration, increase in the bulk density and organic matter, and reduction in the soil porosity and electrical and saturated hydraulic conductivity. Furthermore, gas oil retention was significantly more than kerosene (almost 40%) in the soil. The survey of SWRC indicated that the contaminated soil samples had a little higher amount of moisture retention (just under 15% in most cases) compared to the unpolluted ones during this 3-month period. The parametric analysis of SWRC demonstrated an increase in the saturated water content, Θ s, from nearly 49% in the control sample to just under 53% in the polluted ones. Contaminants not only decreased the residual water content, Θ r, but also reduced the SWRC gradient, n, and amount of α parameter. The evaluation of both equations revealed more accurate prediction of SWRC's parameters by Van Genukhten compared to those of Brooks and Corey.

  18. Partitioning of organic aerosol components between gas phase and particulate phase

    Science.gov (United States)

    Folkers, M.; Mentel, T. F.; Henk, H.; Tillmann, R.; Wahner, A.; Otjes, R. P.; Blom, M. J.; ten Brink, H. M.

    2003-12-01

    To understand the role of organics in aerosols both the particulate composition and the gas/vapor phase composition must determined simultaneously. Ammonium sulfates and dicarboxylic acids are major components of continental, tropospheric aerosols. We performed two experiments in which we studied the partitioning of organic aerosol components between the gas and the particulate phase. As model systems we chose (NH4HSO_4 + glutaric acid) aerosol and ((NH4)HSO_4 + methyl glyoxal) aerosol (an oxidation product of isoprene). The experiment were performed in the large Aerosol Chamber at the FZ-Jülich at room temperature. The relative humidity was constantly increased in the course of the experiment (40 -> 90% r.h., 60 -> 90% r.h.).\

  19. Radioactive contamination of Natural Material and Decontamination methods In the Oil and Gas Industry

    International Nuclear Information System (INIS)

    Alsumiri, M.; Qsem, N.

    2007-01-01

    The aim of our papers was to elaborate the sources materials and the classification of waste radioactive contamination in oil field equipment can contain hard radioactive scales and sludges which appear as coatings or sediments NORM is brought to the surface through the down hole tubing as part of oil -gas -water mixture. Decontamination methods ,Manual removal and vacuum cleaning Mechanical dry and wet abrasive methods, Chemical descaling ,High pressure water jetting . Optimize occupational and public doses - minimize risk to humans and environment but be cost-effective

  20. Slurry-phase bioremediation of creosote and petroleum-contaminated soils

    International Nuclear Information System (INIS)

    Rutherford, P.M.; Luther, S.M.; Dudas, M.J.; McGill, W.B.; Salloum, M.J.; Banerjee, D.K.; Gray, M.R.; Pickard, M.A.

    1998-01-01

    The objective of this work was to study the extent and pattern of contaminant biodegradation during slurry-phase bioremediation of four industrially-contaminated soils (< 3% contamination) to obtain further insight into the factors which may control biodegradation. Two soils (sand and silty clay) were contaminated with creosote compounds, and two soils (loam and clay) were contaminated with petroleum compounds. Degradation of TEO over 10 weeks was most extensive in the clay soil (43%) and least in the sand soil (25%). The rate of TEO biodegradation slowed, or plateaued, in the clay soil after 2-4 weeks. Degradation of total GC-elutable compounds was 1.4- (sand) to 2.7-fold (loam) greater than TEO degradation, and a plateauing of some GC-elutable component classes occurred in most soils within 10 weeks. Plateauing of contaminant concentrations in soils was attributed to bioavailability limitations due to strong partitioning into the residual contaminant matrix. In addition, microbial competence limited biodegradation in the sand soil. (author)

  1. Slurry-phase bioremediation of creosote and petroleum-contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Rutherford, P.M.; Luther, S.M.; Dudas, M.J.; McGill, W.B.; Salloum, M.J. [University of Alberta (Canada). Dept. of REnewable Resources; Banerjee, D.K.; Gray, M.R. [University of Alberta (Canada). Dept. of Chemical and Materials Engineering; Pickard, M.A. [University of Alberta (Canada). Dept. of Biological Sciences

    1998-12-31

    The objective of this work was to study the extent and pattern of contaminant biodegradation during slurry-phase bioremediation of four industrially-contaminated soils (< 3% contamination) to obtain further insight into the factors which may control biodegradation. Two soils (sand and silty clay) were contaminated with creosote compounds, and two soils (loam and clay) were contaminated with petroleum compounds. Degradation of TEO over 10 weeks was most extensive in the clay soil (43%) and least in the sand soil (25%). The rate of TEO biodegradation slowed, or plateaued, in the clay soil after 2-4 weeks. Degradation of total GC-elutable compounds was 1.4- (sand) to 2.7-fold (loam) greater than TEO degradation, and a plateauing of some GC-elutable component classes occurred in most soils within 10 weeks. Plateauing of contaminant concentrations in soils was attributed to bioavailability limitations due to strong partitioning into the residual contaminant matrix. In addition, microbial competence limited biodegradation in the sand soil. (author)

  2. Gulf of Mexico offshore operations monitoring experiment (GOOMEX), phase I : sublethal responses to contaminant exposure - introduction and overview

    International Nuclear Information System (INIS)

    Kennicutt, M.C.; Green, R.H.; Montagna, P.

    1996-01-01

    The Gulf of Mexico Offshore Operations Monitoring Experiment (GOOMEX) is a three-phase study to test and evaluate a range of biological, biochemical, and chemical methodologies to detect and assess chronic sublethal biological impacts in the vicinity of long-duration activities associated with oil and gas exploration and production. A chronic impact is defined as an effect on the biota caused by exposure to the long-term accumulation of chemicals in the environment. The basic program, comprising four field activities over a 2-yr period, was designed to detect nearfield impacts and contaminant gradients extending out from each site. Five test sites were evaluated and three selected as most appropriate for long-term study: MU-A85, MAI-686, and HI-A389. The sampling design included a radial pattern with stations at 30-50, 100, 200, 500, and 3000 m distance and employed a dose-response model to test the hypotheses that biological, chemical, and biochemical variations are due to platform-derived contaminants. Study components included contaminant (trace metals and hydrocarbons) analysis in sediments, pore waters, and biological tissues; assemblage analysis of benthic meiofauna, infauna, and epifauna, assessment of community health based on life history and reproduction studies; and the induction of detoxification responses. (author). 57 refs., 9 tabs., 5 figs

  3. Continuous-wave terahertz by photomixing: applications to gas phase pollutant detection and quantification

    Science.gov (United States)

    Hindle, Francis; Cuisset, Arnaud; Bocquet, Robin; Mouret, Gaël

    2008-03-01

    Recent advances in the development of monochromatic continuous-wave terahertz sources suitable for high resolution gas phase spectroscopy and pollution monitoring are reviewed. Details of a source using an ultra fast opto-electronic photomixing element are presented. The construction of a terahertz spectrometer using this source has allowed spectroscopic characterisation and application studies to be completed. Analysis of H 2S and OCS under laboratory conditions are used to demonstrate the spectrometer performance, and the determination of the transition line strengths and pressure self broadening coefficients for pure rotational transitions of OCS. The spectral purity 5 MHz, tunability 0.3 to 3 THz, and long wavelength ≈200 μm of this source have been exploited to identify and quantify numerous chemical species in cigarette smoke. The key advantages of this frequency domain are its high species selectivity and the possibility to make reliable measurements of gas phase samples heavily contaminated by aerosols and particles. To cite this article: F. Hindle et al., C. R. Physique 9 (2008).

  4. Sources and potential health risk of gas phase PAHs in Hexi Corridor, Northwest China.

    Science.gov (United States)

    Mao, Xiaoxuan; Yu, Zhousuo; Ding, Zhongyuan; Huang, Tao; Ma, Jianmin; Zhang, Gan; Li, Jun; Gao, Hong

    2016-02-01

    Gas phase polycyclic aromatic hydrocarbons (PAHs) in Hexi Corridor, Northwest China were determined during heating and non-heating seasons, respectively, using passive air samplers. Polyurethane foam (PUF) disks were chosen as the sampling medium. Fifteen PAHs out of the 16 PAHs classified by the United States Environmental Protection Agency (U.S. EPA) were detected in this field sampling investigation. The atmospheric levels of sampled PAHs were higher at urban sites than that at rural sites among 14 sampling sites and increased during heating season. The highest concentration (11.34 ng m(-3)) was observed in Lanzhou during the heating season, the capital and largest industrial city of Gansu Province. PAH contamination in air was dominated by three aromatic ring congeners. Possible sources of PAHs were apportioned using PAH species ratios and the principle component analysis (PCA) combined with a multiple linear regression (MLR) method. Fossil fuel consumption was identified to be the predominant source of PAHs over Hexi Corridor, accounting for 43 % of the concentration of total (15) PAHs. Backward and forward trajectory and cluster analysis were also carried out to identify potential origins of PAHs monitored at several urban and rural sites. Lung cancer risk of local residents to gas phase PAHs via inhalation exposure throughout the province was found to be around a critical value of the lung cancer risk level at 10(-6) recommended by the U.S. EPA risk assessment guideline.

  5. Brine contamination to aquatic resources from oil and gas development in the Williston Basin, United States

    Science.gov (United States)

    Gleason, Robert A.; Contributions by Chesley-Preston, Tara L.; Coleman, James L.; Haines, Seth S.; Jenni, Karen E.; Nieman, Timothy L.; Peterman, Zell E.; van der Burg, Max Post; Preston, Todd M.; Smith, Bruce D.; Tangen, Brian A.; Thamke, Joanna N.; Gleason, Robert A.; Tangen, Brian A.

    2014-01-01

    The Williston Basin, which includes parts of Montana, North Dakota, and South Dakota in the United States and the provinces of Manitoba and Saskatchewan in Canada, has been a leading domestic oil and gas producing region for more than one-half a century. Currently, there are renewed efforts to develop oil and gas resources from deep geologic formations, spurred by advances in recovery technologies and economic incentives associated with the price of oil. Domestic oil and gas production has many economic benefits and provides a means for the United States to fulfill a part of domestic energy demands; however, environmental hazards can be associated with this type of energy production in the Williston Basin, particularly to aquatic resources (surface water and shallow groundwater) by extremely saline water, or brine, which is produced with oil and gas. The primary source of concern is the migration of brine from buried reserve pits that were used to store produced water during recovery operations; however, there also are considerable risks of brine release from pipeline failures, poor infrastructure construction, and flow-back water from hydraulic fracturing associated with modern oilfield operations. During 2008, a multidisciplinary (biology, geology, water) team of U.S. Geological Survey researchers was assembled to investigate potential energy production effects in the Williston Basin. Researchers from the U.S. Geological Survey participated in field tours and met with representatives from county, State, tribal, and Federal agencies to identify information needs and focus research objectives. Common questions from agency personnel, especially those from the U.S. Fish and Wildlife Service, were “are the brine plumes (plumes of brine-contaminated groundwater) from abandoned oil wells affecting wetlands on Waterfowl Production Areas and National Wildlife Refuges?” and “are newer wells related to Bakken and Three Forks development different than the older

  6. Comparison of solid and liquid-phase bioassays using ecoscores to assess contaminated soils

    International Nuclear Information System (INIS)

    Lors, Christine; Ponge, Jean-Francois; Martinez Aldaya, Maite; Damidot, Denis

    2011-01-01

    Bioassays on aqueous and solid phases of contaminated soils were compared, belonging to a wide array of trophic and response levels and using ecoscores for evaluating ecotoxicological and genotoxicological endpoints. The method was applied to four coke factory soils contaminated mainly with PAHs, but also to a lesser extent by heavy metals and cyanides. Aquatic bioassays do not differ from terrestrial bioassays when scaling soils according to toxicity but they are complementary from the viewpoint of ecological relevance. Both aquatic and terrestrial endpoints are strongly correlated with concentrations of 3-ring PAHs. This evaluation procedure allows us to propose a cost-effective battery which embraces a wide array of test organisms and response levels: it includes two rapid bioassays (Microtox) and springtail avoidance), a micronucleus test and three bioassays of a longer duration (algal growth, lettuce germination and springtail reproduction). This battery can be recommended for a cost-effective assessment of polluted/remediated soils. - Highlights: → Comparison of liquid- and solid-phase bioassays on contaminated soils, using ecoscores. → Complementarity of liquid- and solid-phase bioassays for the evaluation of environmental hazards. → Proposal for a restricted battery of 5 most sensitive tests. → Use of this restricted battery for a cost-effective assessment of polluted/remediated soils. - Aqueous and solid phases of contaminated soils give similar results in terms of toxicity but are complementary for the evaluation of environmental hazards by ecoscores.

  7. Frequency metrology of a photomixing source for gas phase spectroscopy

    Science.gov (United States)

    Hindle, Francis; Mouret, Gael; Yang, Chun; Cuisset, Arnaud; Bocquet, Robin; Lours, Michel; Rovera, Daniele

    2010-08-01

    The availability of frequency combs has opened new possibilities for the measurement of optical frequencies. Photomixing is an attractive solution for high resolution THz spectroscopy of gases due to the narrow spectral resolution and ability to access the 100 GHz to 3.5 THz range. One limitation of present photomixing spectrometers is the accuracy with which the THz frequency is established. Measurement of the centre frequency gas phase molecular transitions requires an accuracy better than 100 kHz in order to allow spectroscopic constants to be determined. Standard optical techniques like those employed in wavelength meters can only provide accuracies in the order of 50 MHz. We have used a turnkey fibre based frequency comb and a standard photomixing configuration to realize a THz synthesizer with an accuracy of around 50kHz. Two ECDLs used to pump the photomixer are phase locked onto the frequency comb and provide a tuning range of 10 MHz. In order to extend the tuning range an additional phase locked ECLD has been added to obtain a range in excess of 100 MHz. The absorption profiles of many Doppler limited transitions of carbonyl sulphide and formaldehyde have been measured to validate this instrument.

  8. Visible and ultraviolet spectroscopy of gas phase protein ions.

    Science.gov (United States)

    Antoine, Rodolphe; Dugourd, Philippe

    2011-10-06

    Optical spectroscopy has contributed enormously to our knowledge of the structure and dynamics of atoms and molecules and is now emerging as a cornerstone of the gas phase methods available for investigating biomolecular ions. This article focuses on the UV and visible spectroscopy of peptide and protein ions stored in ion traps, with emphasis placed on recent results obtained on protein polyanions, by electron photodetachment experiments. We show that among a large number of possible de-excitation pathways, the relaxation of biomolecular polyanions is mainly achieved by electron emission following photo-excitation in electronically excited states. Electron photodetachment is a fast process that occurs prior to relaxation on vibrational degrees of freedom. Electron photodetachment yield can then be used to record gas phase action spectra for systems as large as entire proteins, without the limitation of system size that would arise from energy redistribution on numerous modes and prevent fragmentation after the absorption of a photon. The optical activity of proteins in the near UV is directly related to the electronic structure and optical absorption of aromatic amino acids (Trp, Phe and Tyr). UV spectra for peptides and proteins containing neutral, deprotonated and radical aromatic amino acids were recorded. They displayed strong bathochromic shifts. In particular, the results outline the privileged role played by open shell ions in molecular spectroscopy which, in the case of biomolecules, is directly related to their reactivity and biological functions. The optical shifts observed are sufficient to provide unambiguous fingerprints of the electronic structure of chromophores without the requirement of theoretical calculations. They constitute benchmarks for calculating the absorption spectra of chromophores embedded in entire proteins and could be used in the future to study biochemical processes in the gas phase involving charge transfer in aromatic amino acids

  9. Hydrogeologic and soil gas evaluation of groundwater contamination at a municipal landfill in New York State

    International Nuclear Information System (INIS)

    Danahy, T.V.; Howard, W.O.; Wolterding, D.J.

    1988-01-01

    A hydrogeologic study of municipal sanitary landfill located in east-central New York was performed under contract with the New York State Department of Environmental Conservation (NYSDEC). Project activities included a volatile organic soil gas survey using the Petrex Static Collection Technique, installation of six monitoring wells, surface and downhole geophysics, surface and groundwater sampling and hydrogeologic interpretation. The soil gas survey identified downgradient areas of soil and/or groundwater contamination which were further investigated by the installation of monitoring wells. At the site the unconfined water table aquifer consists of fluvial (K = 3.5 x 10 -3 cm/sec), glaciodeltaic (K = 8.5 x 10 -3 cm/sec) and glaciolacustrine (K = 4.1 x 10 -3 cm/sec) sediments. Groundwater flow is generally to the south in a semi-radial pattern at approximately 2 to 5 feet per day. The base of this primary water supply aquifer is defined by a leaky glacial till aquitard which occurs above the siltstone-shale bedrock aquifer. Reasonably good correlation exists between volatile organic soil gas mapping and groundwater contamination. Headspace analysis of pre-existing monitoring wells substantiated the migration and volatilization of organic compounds. Groundwater quality results include elevated levels of chlorinated hydrocarbon, aromatic hydrocarbon, metal and indicator parameters with respect to background conditions. Iron, manganese, phenol, benzene, 1,2-dichloroethane and two PCB compounds exceeded New York State groundwater standards or guidance values. GC/MS and Carbon-14 analyses indicate a significant amount of methane gas has been generated by landfilling activities

  10. Biases in Metallicity Measurements from Global Galaxy Spectra: The Effects of Flux Weighting and Diffuse Ionized Gas Contamination

    Science.gov (United States)

    Sanders, Ryan L.; Shapley, Alice E.; Zhang, Kai; Yan, Renbin

    2017-12-01

    Galaxy metallicity scaling relations provide a powerful tool for understanding galaxy evolution, but obtaining unbiased global galaxy gas-phase oxygen abundances requires proper treatment of the various line-emitting sources within spectroscopic apertures. We present a model framework that treats galaxies as ensembles of H II and diffuse ionized gas (DIG) regions of varying metallicities. These models are based upon empirical relations between line ratios and electron temperature for H II regions, and DIG strong-line ratio relations from SDSS-IV MaNGA IFU data. Flux-weighting effects and DIG contamination can significantly affect properties inferred from global galaxy spectra, biasing metallicity estimates by more than 0.3 dex in some cases. We use observationally motivated inputs to construct a model matched to typical local star-forming galaxies, and quantify the biases in strong-line ratios, electron temperatures, and direct-method metallicities as inferred from global galaxy spectra relative to the median values of the H II region distributions in each galaxy. We also provide a generalized set of models that can be applied to individual galaxies or galaxy samples in atypical regions of parameter space. We use these models to correct for the effects of flux-weighting and DIG contamination in the local direct-method mass-metallicity and fundamental metallicity relations, and in the mass-metallicity relation based on strong-line metallicities. Future photoionization models of galaxy line emission need to include DIG emission and represent galaxies as ensembles of emitting regions with varying metallicity, instead of as single H II regions with effective properties, in order to obtain unbiased estimates of key underlying physical properties.

  11. Removal of Contaminants from Waste Streams at Gas Evolving Flow-Through Porous Electrodes

    International Nuclear Information System (INIS)

    Mahmoud Saleh, M.

    1999-01-01

    Electrochemical techniques have been used for the removal of inorganic and organic toxic materials from industrial waste streams. One of the most important branch of these electrochemical techniques is the flow-through porous electrode. Such systems allow for the continuous operation and hence continuous removal of the contaminants from waste streams at high rates and high efficiency. However, when there is an evolution of gas bubbles with the removal process, the treatment process needs a much different treatment of both the design and the mathematical treatment of the such these systems. The evolving gas bubbles within the electrode decrease the pore electrolyte conductivity of the porous electrodes, decrease the efficiency and make the current more non-uniform. This cause the under utilization of the reaction area and finally make the electrode inoperable. In this work the harmful effects of the gas bubbles on the performance of the porous electrode will be modeled. The model accounts for the effects of kinetic, mass transfer and gas bubbles resistance on the overall performance of the electrode. This will help in optimizing the operating conditions and the cell design

  12. Gas-phase experiments on Au(III) photochemistry.

    Science.gov (United States)

    Marcum, Jesse C; Kaufman, Sydney H; Weber, J Mathias

    2011-04-14

    Irradiation of AuCl(4)(-) and AuCl(2)(OH)(2)(-) in the gas-phase using ultraviolet light (220-415 nm) leads to their dissociation. Observed fragment ions for AuCl(4)(-) are AuCl(3)(-) and AuCl(2)(-) and for AuCl(2)(OH)(2)(-) are AuCl(2)(-) and AuClOH(-). All fragment channels correspond to photoreduction of the gold atom to either Au(II) or Au(I) depending on the number of neutral ligands lost. Fragment branching ratios of AuCl(4)(-) are observed to be highly energy dependent and can be explained by comparison of the experimental data to calculated threshold energies obtained using density functional theory. The main observed spectral features are attributed to ligand-to-metal charge transfer transitions. These results are discussed in the context of the molecular-level mechanisms of Au(III) photochemistry.

  13. Synthesis and Gas Phase Thermochemistry of Germanium-Containing Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Classen, Nathan Robert [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    The driving force behind much of the work in this dissertation was to gain further understanding of the unique olefin to carbene isomerization observed in the thermolysis of 1,1-dimethyl-2-methylenesilacyclobutane by finding new examples of it in other silicon and germanium compounds. This lead to the examination of a novel phenylmethylenesilacyclobut-2-ene, which did not undergo olefin to carbene rearrangement. A synthetic route to methylenegermacyclobutanes was developed, but the methylenegermacyclobutane system exhibited kinetic instability, making the study of the system difficult. In any case the germanium system decomposed through a complex mechanism which may not include olefin to carbene isomerization. However, this work lead to the study of the gas phase thermochemistry of a series of dialkylgermylene precursors in order to better understand the mechanism of the thermal decomposition of dialkylgermylenes. The resulting dialkylgermylenes were found to undergo a reversible intramolecular β C-H insertion mechanism.

  14. Conformational Study of Taurine in the Gas Phase

    Science.gov (United States)

    Cortijo, Vanessa; Sanz, M. Eugenia; López, Juan C.; Alonso, José L.

    2009-08-01

    The conformational preferences of the amino sulfonic acid taurine (NH2-CH2-CH2-SO3H) have been investigated in the gas phase by laser ablation molecular beam Fourier transform microwave spectroscopy (LA-MB-FTMW) in the 6-14 GHz frequency range. One conformer has been observed, and its rotational, centrifugal distortion, and hyperfine quadrupole coupling constants have been determined from the analysis of its rotational spectrum. Comparison of the experimental constants with those calculated theoretically identifies the detected conformer unambiguously. The observed conformer of taurine is stabilized by an intramolecular hydrogen bond O-H···N between the hydrogen of the sulfonic acid group and the nitrogen atom of the amino group.

  15. UV Action Spectroscopy of Gas-Phase Peptide Radicals.

    Science.gov (United States)

    Nguyen, Huong T H; Shaffer, Christopher J; Pepin, Robert; Tureček, František

    2015-12-03

    UV photodissociation (UVPD) action spectroscopy is reported to provide a sensitive tool for the detection of radical sites in gas-phase peptide ions. UVPD action spectra of peptide cation radicals of the z-type generated by electron-transfer dissociation point to the presence of multiple structures formed as a result of spontaneous isomerizations by hydrogen atom migration. N-terminal Cα radicals are identified as the dominant components, but the content of isomers differing in the radical defect position in the backbone or side chain depends on the nature of the aromatic residue with phenylalanine being more prone to isomerization than tryptophan. These results illustrate that spontaneous hydrogen atom migrations can occur in peptide cation-radicals upon electron-transfer dissociation.

  16. Sugar Synthesis from a Gas-Phase Formose Reaction

    Science.gov (United States)

    Jalbout, Abraham F.; Abrell, Leif; Adamowicz, Ludwik; Polt, Robin; Apponi, A. J.; Ziurys, L. M.

    2007-06-01

    Prebiotic possibilities for the synthesis of interstellar ribose through a protic variant of the formose reaction under gas-phase conditions were studied in the absence of any known catalyst. The ion-molecule reaction products, diose and triose, were sought by mass spectrometry, and relevant masses were observed. Ab initio calculations were used to evaluate protic formose mechanism possibilities. A bilateral theoretical and experimental effort yielded a physical model for glycoaldehyde generation whereby a hydronium cation can mediate formaldehyde dimerization followed by covalent bond formation leading to diose and water. These results advance the possibility that ion-molecule reactions between formaldehyde (CH2O) and H3O+ lead to formose reaction products and inform us about potential sugar formation processes in interstellar space.

  17. Radiation polymerization of tetrafluoroethylene in gas-phase

    International Nuclear Information System (INIS)

    Enslin, S.E.; Schnautz, N.G.; Van der Ende, E.

    1986-01-01

    The radiation polymerization of tetrafluoroethylene in gas-phase was studied over a temperature range of -80 to 200 degrees Celsius and an irradiation dose-rate of 0,30 to 10,8 kGy h sup(-1). The rate of polymerization was observed during the course of the polymerization process, to be a zero-order function of monomer pressure. However, the rate of polymerization was profoundly influenced by the initial monomer pressure, in this case exhibiting a 4,6-order dependence. The rate of polymerization was also observed to exhibit a 0,36-order dependence on radiation intensity. Both the rate of polymerization and the molecular mass of the product, polytetrafluoroethylene, reached maximum values over the temperature range of 90 to 150 degrees Celsius. The activation energy for the polymerization process was determined to be 8,7 kJ mol sup(-1) over the temperature range of -80 to 90 degrees Celsius

  18. Gas Phase Sulfur, Chlorine and Potassium Chemistry in Biomass Combustion

    DEFF Research Database (Denmark)

    Løj, Lusi Hindiyarti

    2007-01-01

    the uncertainties. In the present work, the detailed kinetic model for gas phase sulfur, chlorine, alkali metal, and their interaction has been updated. The K/O/H/Cl chemistry, S chemistry, and their interaction can reasonably predict a range of experimental data. In general, understanding of the interaction...... between K-containing species and radical pool under combustion conditions has been improved. The available K/O/H/Cl chemistry has been updated by using both experimental work and detailed kinetic modeling. The experimental work was done by introducing gaseous KCl to CO oxidation system under reducing...... level, but the effect levels off at high concentrations. The experimental data were interpreted in terms of a detailed chemical kinetic model and used to update the K/O/H/Cl chemistry. The oxidation of SO2 to SO3 under combustion conditions has been suggested to be the rate limiting step in the gaseous...

  19. Technical Procedures Management in Gas-Phase Detoxification Laboratory

    International Nuclear Information System (INIS)

    Cardona Garcia, A. I.; Sanchez Cabrero, B.

    2000-01-01

    The natural cycle of Volatile Organic Compounds (VOCs) has been disturbed by the industrial and socioeconomic activities of human beings. This imbalance in the environment has affected the ecosystems and the human health. Initiatives have been planned to mitigate these adverse effects. In order to minimize the hazardous effects, initiatives have been proposed for the treatment of gaseous emissions. The solar photo catalysis appears as a clear and renewable technology in front of the conventional ones.In CIEMAT this line is being investigated as the base of a future implementation at a pre industrial scale.Technical procedures are written in this document for testing Gas-Phase detoxification at lab scale in the Renewable Energy Department (DER) CIEMAT- Madrid to eliminate the VOCs by using the solar photo catalysis technology. (Author) 34 refs

  20. Multiphase flow and transport caused by spontaneous gas phase growth in the presence of dense non-aqueous phase liquid.

    Science.gov (United States)

    Roy, James W; Smith, James E

    2007-01-30

    Disconnected bubbles or ganglia of trapped gas may occur below the top of the capillary fringe through a number of mechanisms. In the presence of dense non-aqueous phase liquid (DNAPL), the disconnected gas phase experiences mass transfer of dissolved gases, including volatile components from the DNAPL. The properties of the gas phase interface can also change. This work shows for the first time that when seed gas bubbles exist spontaneous gas phase growth can be expected to occur and can significantly affect water-gas-DNAPL distributions, fluid flow, and mass transfer. Source zone behaviour was observed in three different experiments performed in a 2-dimensional flow cell. In each case, a DNAPL pool was created in a zone of larger glass beads over smaller glass beads, which served as a capillary barrier. In one experiment effluent water samples were analyzed to determine the vertical concentration profile of the plume above the pool. The experiments effectively demonstrated a) a cycle of spontaneous gas phase expansion and vertical advective mobilization of gas bubbles and ganglia above the DNAPL source zone, b) DNAPL redistribution caused by gas phase growth and mobilization, and c) that these processes can significantly affect mass transport from a NAPL source zone.

  1. Hydrogen trapping properties of Zr-based intermetallic compounds in the presence of CO contaminant gas

    Energy Technology Data Exchange (ETDEWEB)

    Prigent, Jocelyn [Chimie Metallurgie des Terres Rares, ICMPE-UMR 7182, CNRS, 2-8 rue Henri Dunant, 94320 Thiais (France); Latroche, Michel, E-mail: latroche@icmpe.cnrs.fr [Chimie Metallurgie des Terres Rares, ICMPE-UMR 7182, CNRS, 2-8 rue Henri Dunant, 94320 Thiais (France); Leoni, Elisa; Rohr, Valentin [AREVA NC, 1, rue des Herons, 78182 Montigny Le Bretonneux (France)

    2011-09-15

    Research highlights: > Hydrogen absorption in the presence of carbon monoxide is reported for several Zr rich intermetallic compounds. > Absorption rates have been determined and compared for pure and CO-containing hydrogen gases. > Using intermetallic compounds as getter materials in the presence of contaminant gases has been demonstrated. - Abstract: Intermetallic compounds, as hydrogen getters, are considered to control the quantity of hydrogen generated in radioactive waste packaging. The compounds ZrCo, Zr{sub 2}Fe and a Zr-rich Zr-Ti-V alloy have been chosen as they form very stable hydrides at ambient temperature. However, other gases are produced in the packaging such as carbon monoxide, a gas known to poison the surface of intermetallic compounds and to hinder the hydrogen sorption reaction. The three Zr-based compounds have been first characterized regarding their metallurgical state and their gas sorption properties toward pure hydrogen. Then, the sorption properties of the activated materials have been studied using a mixture of 5 vol.% CO + 95 vol.% H{sub 2}. We demonstrated that though the presence of CO sharply slows down the reaction rate the activated compounds still show significant sorption properties. Therefore, the presence of contaminant gases is not detrimental for the target application.

  2. Precursor-Less Coating of Nanoparticles in the Gas Phase

    Directory of Open Access Journals (Sweden)

    Tobias V. Pfeiffer

    2015-03-01

    Full Text Available This article introduces a continuous, gas-phase method for depositing thin metallic coatings onto (nanoparticles using a type of physical vapor deposition (PVD at ambient pressure and temperature. An aerosol of core particles is mixed with a metal vapor cloud formed by spark ablation by passing the aerosol through the spark zone using a hollow electrode configuration. The mixing process rapidly quenches the vapor, which condenses onto the core particles at a timescale of several tens of milliseconds in a manner that can be modeled as bimodal coagulation. Gold was deposited onto core nanoparticles consisting of silver or polystyrene latex, and silver was deposited onto gold nanoparticles. The coating morphology depends on the relative surface energies of the core and coating materials, similar to the growth mechanisms known for thin films: a coating made of a substance having a high surface energy typically results in a patchy coverage, while a coating material with a low surface energy will normally “wet” the surface of a core particle. The coated particles remain gas-borne, allowing further processing.

  3. Dimerization Products of Chloroprene are Background Contaminants Emitted from ALTEF (Polyvinylidene Difluoride) Gas Sampling Bags.

    Science.gov (United States)

    Kwak, Jae; Fan, Maomian; Martin, Jennifer A; Ott, Darrin K; Grigsby, Claude C

    2017-01-01

    Gas sampling bags have been used for collecting air samples. Tedlar bags are most commonly used, but bleed background chemicals such as N,N-dimethylacetamide and phenol. It is often necessary to remove the contaminant by flushing the bags with pure nitrogen or air. In this study, we identified four chloroprene dimerization products as background contaminants emitted from ALTEF bags that are made of a proprietary polyvinylidene difluoride (PVDF). No monomer chloroprene was detected in the bags analyzed. All of the dimers gradually increased once bags were filled with nitrogen due to diffusion from the bag surface. Flushing the bags with nitrogen reduced their concentrations, but was not effective for removing the contaminants. When the bags that had been flushed with nitrogen 5 times were left for 24 h, they increased again, indicating that the dimers were constantly emitted from the ALTEF bag surface. To our knowledge, these compounds have never been demonstrated in ALTEF or other PVDF bags. Our finding indicates that ALTEF might be incorporated with Neoprene (chloroprene-based polymer) during its manufacturing process.

  4. Compressorless Gas Storage and Regenerative Hydrogen Purification, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Microwave regenerative sorption media gas storage/delivery techniques are proposed to address both compressed gas management and hydrogen purification requirements...

  5. Contaminant Characterization of Effluent from Pennsylvania Brine Treatment, Inc., Josephine Facility: Implications for Disposal of Oil and Gas Flowback Fluids from Brine Treatment Plants

    Science.gov (United States)

    The PBT-Josephine Facility accepts only wastewater from the oil and gas industry. This report describes the concentrations of selected contaminants in the effluent water and compares the contaminant effluent concentrations to state and federal standards.

  6. Inorganic Contaminants Associated with the Extraction of Unconventional Gas.Initial Analysis and Risk Assessment

    International Nuclear Information System (INIS)

    Xu, L.; Hurtado, A.; Recreo, F.; Eguilior, S.

    2015-01-01

    The latest technological developments in horizontal drilling and hydraulic fracturing are driving a commercial scale extraction of unconventional fossil fuels in various regions of the world. Europe's position in relation to the exploitation of unconventional fossil fuels is this has to be made under a paradigm of coherence between the technical and economic-financial aspects and environments and public trust, which are essential and which will eventually would enable the viability of exploiting these resources.This requires, by those decision makers, both industry and regulators, a comprehensive management of the risks associated with these exploitations, which implies the need to develop tools of analysis and assessment to environmental impact and risk. The exploitation of unconventional hydrocarbons in formations of shale requires the creation of a network of artificial fractures to connect with production well Horizontal wells are drilled for this purpose and go on for several km into the shale formation. During drilling, a mixture of oil, gas and formation water is pumped to the surface. The water is separated from oil and gas in tanks or pools. The flowback and produced water contains different kinds of chemicals in varying concentrations: salt, oil and other organic compounds, suspended solids, bacteria, naturally occurring radioactive elements (NORM), and any element injected with the fracturing fluid. The concentration of these elements in the water may be increased due to the treatments suffered by flowback and produced water for disposal. Due to the large variability of contaminants in the flowback and produced water and the potentially large volumes involved, the determination of the its composition is essential for proper management of them and to prevent health, safety and environmental risks. This report covers the risk analysis of an unconventional gas extraction project, the initial assessment of the risks associated with the use and

  7. Off-Gas Treatment: Evaluation of Nano-structured Sorbents for Selective Removal of Contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Utgikar, Vivek; Aston, D. Eric; Sabharwall, Piyush

    2018-03-30

    Reprocessing of used nuclear fuel (UNF) is expected to play an important role for sustainable development of nuclear energy by increasing the energy extracted from the fuel and reducing the generation of the high level waste (HLW). However, aqueous reprocessing of UNF is accompanied by emission of off-gas streams containing radioactive nuclides including iodine, krypton, xenon, carbon, and tritium. Volatile iodine (129I), and krypton (85Kr) are long lived isotopes which have adverse effects on the environment as well as human health. Development of methods for the capture and long-term storage of radioactive gases is of crucial importance in order to manage their emissions that are anticipated to increase significantly with the growth of nuclear energy. For more than 70 years, porous solid sorbents have been in the forefront of radioactive contaminant removal due to promising results and their advantages such as high removal efficiency, low maintenance cost, simple equipment design and operation over other techniques. The research conducted in this project has focused on development of a novel nanostructured sorbent and its application for the capture of the above two contaminants of interest. Nanostructured carbon polyhedrons supported on Engelhard Titanosilicate-10 sorbent was synthesized using hydrothermal methods and subjected to structural and compositional characterization using various techniques including electron microscopy, Raman, x-ray diffraction and BET surface area analysis. Dynamic sorption experiments conducted using a flow-through column setup yielded information on the thermodynamics and kinetics of sorption in single-contaminant and multi-contaminant streams. Parameters varied in the study included carbon loading, temperature, contact time, contaminant concentration and humidity. The behavior of the system was modeled using models available in literature as well as development of a mass-transfer model from fundamental principles. Experimental

  8. A direct comparison of protein structure in the gas and solution phase: the Trp-cage

    DEFF Research Database (Denmark)

    Patriksson, Alexandra; Adams, Christopher M; Kjeldsen, Frank

    2007-01-01

    Molecular dynamics simulations of zwitterions of the Trp-cage protein in the gas phase show that the most stable ion in vacuo has preserved the charge locations acquired in solution. A direct comparison of the gas and solution-phase structures reveals that, despite the similarity in charge location......, there is significant difference in the structures, with a substantial increase in hydrogen bonds and exposure of hydrophobic parts in the gas phase. The structure of the salt bridge in the gas phase is also much more stable than in the (experimental) solution structure....

  9. Radon as an indicator of environmental contamination by hydrocarbons in free-phase; Radonio como indicador de contaminacao ambiental por hidrocarbonetos em fase livre

    Energy Technology Data Exchange (ETDEWEB)

    Mateus, Crislene

    2016-10-01

    Contaminated sites by NAPL (Non-Aqueous Phase-Liquids) may lead to safety risks to human health and to ecosystems, restrictions to urban development and decrease of real estate value. This work used the radon gas as an indicator for the analysis of subsurface soil gas, once this noble gas presents good solubility in a wide range of NAPL, being partially retained in the NAPL contamination. Therefore, a decrease of the activity of radon in the contaminated soil gas can be expected, due to the high capacity of partitioning of radon in NAPL, which allows that the NAPL retain part of the radon previously available in the soil pores. The survey was carried out at a disused industry, contaminated by low volatile NAPL, located at southeast of Sao Paulo city, from June/14 to May/15. Radon was evaluated by passive detection methodology with CR-39 solid state nuclear track detectors (SSNTD) in ten monitoring stations installed in the contaminated area investigated and named 'A' to 'J'. Radon concentrations average for the eight monitoring stations at non-contaminated locations varied from (22 ± 4) kBq.m{sup -3} to (39 ± 4) kBq.m{sup -3} . For the two monitoring stations assumed as contaminated locations, radon concentrations average were (1.4 ± 0.4) kBq.m{sup -3} and (13 ± 9) kBq.m{sup -3}. The results have shown good agreement between the used method and the conventional environmental investigation techniques, for the majority of the monitoring stations in different seasons. Results obtained with CR-39 detectors varied over the exposure time due to the different seasons. No relation was observed between radon activity concentrations and rain volume accumulated over the different CR-39 exposure times. The lowest {sup 222}Rn activity concentrations occurred in 'G' and 'H' monitoring stations, also verifying by gamma-ray spectrometry, that the low activities are not related to the activity concentration of its father {sup 226}Ra from

  10. Production Decline Analysis for Two-Phase Flow in Multifractured Horizontal Well in Shale Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Wei-Yang Xie

    2015-01-01

    Full Text Available After multistage fracturing, the flowback of fracturing fluid will cause two-phase flow through hydraulic fractures in shale gas reservoirs. With the consideration of two-phase flow and desorbed gas transient diffusion in shale gas reservoirs, a two-phase transient flow model of multistage fractured horizontal well in shale gas reservoirs was created. Accurate solution to this flow model is obtained by the use of source function theory, Laplace transform, three-dimensional eigenvalue method, and orthogonal transformation. According to the model’s solution, the bilogarithmic type curves of the two-phase model are illustrated, and the production decline performance under the effects of hydraulic fractures and shale gas reservoir properties are discussed. The result obtained in this paper has important significance to understand pressure response characteristics and production decline law of two-phase flow in shale gas reservoirs. Moreover, it provides the theoretical basis for exploiting this reservoir efficiently.

  11. Gas-phase synthesis of semiconductor nanocrystals and its applications

    Science.gov (United States)

    Mandal, Rajib

    Luminescent nanomaterials is a newly emerging field that provides challenges not only to fundamental research but also to innovative technology in several areas such as electronics, photonics, nanotechnology, display, lighting, biomedical engineering and environmental control. These nanomaterials come in various forms, shapes and comprises of semiconductors, metals, oxides, and inorganic and organic polymers. Most importantly, these luminescent nanomaterials can have different properties owing to their size as compared to their bulk counterparts. Here we describe the use of plasmas in synthesis, modification, and deposition of semiconductor nanomaterials for luminescence applications. Nanocrystalline silicon is widely known as an efficient and tunable optical emitter and is attracting great interest for applications in several areas. To date, however, luminescent silicon nanocrystals (NCs) have been used exclusively in traditional rigid devices. For the field to advance towards new and versatile applications for nanocrystal-based devices, there is a need to investigate whether these NCs can be used in flexible and stretchable devices. We show how the optical and structural/morphological properties of plasma-synthesized silicon nanocrystals (Si NCs) change when they are deposited on stretchable substrates made of polydimethylsiloxane (PDMS). Synthesis of these NCs was performed in a nonthermal, low-pressure gas phase plasma reactor. To our knowledge, this is the first demonstration of direct deposition of NCs onto stretchable substrates. Additionally, in order to prevent oxidation and enhance the luminescence properties, a silicon nitride shell was grown around Si NCs. We have demonstrated surface nitridation of Si NCs in a single step process using non?thermal plasma in several schemes including a novel dual-plasma synthesis/shell growth process. These coated NCs exhibit SiNx shells with composition depending on process parameters. While measurements including

  12. In situ removal of contamination from soil

    Science.gov (United States)

    Lindgren, Eric R.; Brady, Patrick V.

    1997-01-01

    A process of remediation of cationic heavy metal contamination from soil utilizes gas phase manipulation to inhibit biodegradation of a chelating agent that is used in an electrokinesis process to remove the contamination, and further gas phase manipulation to stimulate biodegradation of the chelating agent after the contamination has been removed. The process ensures that the chelating agent is not attacked by bioorganisms in the soil prior to removal of the contamination, and that the chelating agent does not remain as a new contaminant after the process is completed.

  13. DEVELOPMENT OF MULTI-PHASE AND MULTI-COMPONENT FLOW MODEL WITH REACTION IN POROUS MEDIA FOR RISK ASSESSMENT ON SOIL CONTAMINATION DUE TO MINERAL OIL

    Science.gov (United States)

    Sakamoto, Yasuhide; Nishiwaki, Junko; Hara, Junko; Kawabe, Yoshishige; Sugai, Yuichi; Komai, Takeshi

    In late years, soil contamination due to mineral oil in vacant lots of oil factory and oil field has become obvious. Measure for soil contamina tion and risk assessment are neces sary for sustainable development of industrial activity. Especially, in addition to contaminated sites, various exposure paths for human body such as well water, soil and farm crop are supposed. So it is very important to comprehend the transport phenomena of contaminated material under the environments of soil and ground water. In this study, mineral oil as c ontaminated material consisting of mu lti-component such as aliphatic and aromatic series was modeled. Then numerical mode l for transport phenomena in surface soil and aquifer was constructed. On the basis of modeling for mineral oil, our numerical model consists of three-phase (oil, water and gas) forty three-component. This numerical model becomes base program for risk assessment system on soil contamination due to mineral oil. Using this numerical model, we carried out some numerical simulation for a laboratory-scale experiment on oil-water multi-phase flow. Relative permeability that dominate flow behavior in multi-phase condition was formulated and the validity of the numerical model developed in this study was considered.

  14. Comprehensive two-dimensional gas chromatography for fast characterization of oil contamination

    International Nuclear Information System (INIS)

    Van De Weghe, H.; Vanermen, G.; Gemoets, J.; Lookman, R.; Bertels, D.

    2005-01-01

    Most analytical methods for the characterization of oil contamination rely on gas chromatography. Capillary GC offers a high separation power (peak capacity typically 100 - 500), and by using a boiling point column a volatility based distribution is obtained. However, petrochemical mixtures like mineral oil easily contain more then 5000 compounds, and capillary GC does not succeed in separating such mixtures up to the level of individual components. Analytical results are therefore limited to a classification into boiling point (or equivalent-carbon) fractions. Recent methods refined the classification by fractionation in aromatic and aliphatic hydrocarbons prior to GC-analysis (TPH method, Weisman 1998), and by incorporating water solubility (TTE and OK method, for a detailed description we refer to the Consoil 2005 lecture by R. Lookman 'Oil characterization: assessment of composition, degradation and remediation potential of total petroleum hydrocarbons in soil'). However, besides analytical difficulties and time consuming protocols related with these methods, the resulting classification still remains coarse and the various groups are not univocally chemically identified. Recently, comprehensive two-dimensional GC (GCXGC) was introduced. This technique combines two GC-columns with different separation mechanisms. The two columns are connected by a modulator, a device that traps, focuses and re-injects the peaks that elute from the first column into the second column. Each peak from the first column (representing a number of overlapping peaks) is further separated on the second column. The very high separation power of GCXGC (peak capacity 2000 - 10000) is ideal for the analysis of complex mixtures like mineral oil. Another important feature is the generation of structured chromatograms. Isomers appear as distinct groups in the chromatogram as a result of their similar interaction with the 2D-column phase. For chemical identification comprehensive GC can be

  15. Assessment of Soil-Gas and Soil Contamination at the Former Military Police Range, Fort Gordon, Georgia, 2009-2010

    Science.gov (United States)

    Falls, W. Fred; Caldwell, Andral W.; Guimaraes, Wladmir B.; Ratliff, W. Hagan; Wellborn, John B.; Landmeyer, James E.

    2011-01-01

    Soil gas and soil were assessed for organic and inorganic contaminants at the former military police range at Fort Gordon, Georgia, from May to September 2010. The assessment evaluated organic contaminants in soil-gas samplers and inorganic contaminants in soil samples. This assessment was conducted to provide environmental contamination data to Fort Gordon pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Soil-gas samplers deployed and collected from May 20 to 24, 2010, identified masses above method detection level for total petroleum hydrocarbons, gasoline-related and diesel-related compounds, and chloroform. Most of these detections were in the southwestern quarter of the study area and adjacent to the road on the eastern boundary of the site. Nine of the 11 chloroform detections were in the southern half of the study area. One soil-gas sampler deployed adjacent to the road on the southern boundary of the site detected a mass of tetrachloroethene greater than, but close to, the method detection level of 0.02 microgram. For soil-gas samplers deployed and collected from September 15 to 22, 2010, none of the selected organic compounds classified as chemical agents and explosives were detected above method detection levels. Inorganic concentrations in the five soil samples collected at the site did not exceed the U.S. Environmental Protection Agency regional screening levels for industrial soil and were at or below background levels for similar rocks and strata in South Carolina.

  16. Numerical simulation for gas-liquid two-phase flow in pipe networks

    International Nuclear Information System (INIS)

    Li Xiaoyan; Kuang Bo; Zhou Guoliang; Xu Jijun

    1998-01-01

    The complex pipe network characters can not directly presented in single phase flow, gas-liquid two phase flow pressure drop and void rate change model. Apply fluid network theory and computer numerical simulation technology to phase flow pipe networks carried out simulate and compute. Simulate result shows that flow resistance distribution is non-linear in two phase pipe network

  17. Gas-Phase Thermolysis of a Thioketen-S-Oxide

    DEFF Research Database (Denmark)

    Carlsen, Lars; Egsgaard, Helge; Schaumann, Ernst

    1980-01-01

    The unimolecular gas-phase thermolytic decomposition of 1,1,3,3-tetramethyl-2-thiocarbonylcyclohexane S-oxide (3) has been studied as a function of temperature by a flash vacuum thermolysis (f.v.t.) technique. The products detected are the carbenes (4) and (5), the ketone (6), the keten (7), the ......-thiololactone (11) followed by loss of CO, minor amounts of the ketone (6), formed analogously, and the keten (7), as a result of simple sulphur extrusion.......), the thioketone (8), and the thioketen (9). The product ratio is highly dependent on the thermolysis temperature. The thermolysis of (3) is mechanistically rationalized by assuming the existence of only two concurrent primary processes, which are (a) extrusion of atomic oxygen, leading to the thioketen (9......), and (b) electrocyclic ring closure into the corresponding three-membered oxathiiran (10). The latter is dominant at lower temperatures, whereas higher thermolysis temperatures favour atomic oxygen extrusion. At further elevated temperatures additional concurrent primary reactions, i.e. extrusions of SO...

  18. Experimental Determination of Gas Phase Thermodynamic Properties of Bimolecular Complexes

    Science.gov (United States)

    Hansen, Anne S.; Maroun, Zeina; Mackeprang, Kasper; Kjaergaard, Henrik G.

    2016-06-01

    Accurate determination of the atmospheric abundance of hydrogen bound bimolecular complexes is necessary, as hydrogen bonds are partly responsible for the formation and growth of aerosol particles. The abundance of a complex is related to the Gibbs free energy of complex formation (Δ G), which is often obtained from quantum chemical calculations that rely on calculated values of the enthalpy (Δ H) and entropy (Δ S) of complex formation. However, calculations of Δ H and in particular Δ S are associated with large uncertainties, and accurate experimental values are therefore crucial for theoretical benchmarking studies. Infrared measurements of gas phase hydrogen bound complexes were performed in the 300 to 373 K range, and lead to a purely experimental determination of Δ H using the van't Hoff equation. Equilibrium constants were determined by combining an experimental and calculated OH-stretching intensity, from which values of Δ G and hence Δ S could be determined. Thus we can determine Δ G, Δ H and Δ S for a bimolecular complex. We find that in the 300 to 373 K temperature range the determined Δ H and Δ S values are independent of temperature.

  19. Effect of elevated carrier-gas pressure on hydraulic characteristics of gas-solid particle two-phase flow

    International Nuclear Information System (INIS)

    Timoshenko, V.I.; Knyshenko, Y.V.; Kopysov, V.F.; Gromov, E.N.

    1992-01-01

    The effect of elevated gas pressure on the hydraulic resistance and critical velocity of a two-phase flow is studied on a pneumatic-transport bench. It is established that for each working-pressure level there exists a limiting solid-phase concentration, the exceeding of which causes an abrupt rise in hydraulic resistance. 16 refs., 3 figs

  20. An algorithm for testing of gas distribution phases in the internal combustion engines

    Directory of Open Access Journals (Sweden)

    T. Nicu

    1999-10-01

    Full Text Available A method and algorithm for testing the gas distribution phases of internal combustion engines are proposed. This method allows a way of testing the gas distribution phases, based on direct and continuous measurements of pressure in cylinders and negative pressure in the intake manifold for using in the real time.

  1. Homolytic iodination and nitration of some benzene derivatives in the gas phase

    International Nuclear Information System (INIS)

    Vonk, W.F.M.

    1980-01-01

    Two gas phase reactions, involving the iodination and nitration of benzene derivatives, are described. The experimental techniques of the apparatus and the methods used are outlined. The kinetic H/D isotope effect in the gas phase nitration of benzene with NO 2 is determined. (C.F.)

  2. Method for detection of trace metal and metalloid contaminants in coal-generated fuel gas using gas chromatography/ion trap mass spectrometry.

    Science.gov (United States)

    Rupp, Erik C; Granite, Evan J; Stanko, Dennis C

    2010-07-15

    There exists an increasing need to develop a reliable method to detect trace contaminants in fuel gas derived from coal gasification. While Hg is subject to current and future regulations, As, Se, and P emissions may eventually be regulated. Sorbents are the most promising technology for the removal of contaminants from coal-derived fuel gas, and it will be important to develop a rapid analytical detection method to ensure complete removal and determine the ideal time for sorbent replacement/regeneration in order to reduce costs. This technical note explores the use of a commercial gas chromatography/ion trap mass spectrometry system for the detection of four gaseous trace contaminants in a simulated fuel gas. Quantitative, repeatable detection with limits at ppbv to ppmv levels were obtained for arsine (AsH(3)), phosphine (PH(3)), and hydrogen selenide (H(2)Se), while qualitative detection was observed for mercury. Decreased accuracy and response caused by the primary components of fuel gas were observed.

  3. Detecting buried radium contamination using soil-gas and surface-flux radon meaurements

    International Nuclear Information System (INIS)

    Karp, K.E.

    1988-06-01

    The Technical Measurements Center (TMC) has investigated the effectiveness of using radon soil-gas under surface-flux measurments to locate radium contamination that is buried sufficiently deep to be undetectable by surface gamma methods. At the first test site studied, an indication of a buried source was revealed by mapping anomalous surface-flux and soil-gas concentrations in the near surface overburden. The mapped radon anomalies were found to correspond in rough outline to the shape of the areal extent of the deposit as determined by borehole gamma-ray logs. The 5.9pCi/g radium deposit, buried 2 feet below the surface, went undetected by conventional surface gamma measurements. Similar results were obtained at the second test site where radon and conventional surface gamma measurements were taken in an area having radium concentrations ranging from 13.3 to 341.0 pCi/g at a depth of 4 feet below the surface. The radon methods were found to have a detection limit for buried radium lower than that of the surface gamma methods, as evidenced by the discovery of the 13.3 pCi/g deposit which went undetected by the surface gamma methods. 15 refs., 33 figs., 8 tabs

  4. Importance of the gas phase role to the prediction of energetic material behavior: An experimental study

    Science.gov (United States)

    Ali, A. N.; Son, S. F.; Asay, B. W.; Sander, R. K.

    2005-03-01

    Various thermal (radiative, conductive, and convective) initiation experiments are performed to demonstrate the importance of the gas phase role in combustion modeling of energetic materials (EM). A previously published condensed phase model that includes a predicted critical irradiance above which ignition is not possible is compared to experimental laser ignition results for octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 2,4,6-trinitrotoluene (TNT). Experimental results conflict with the predicted critical irradiance concept. The failure of the model is believed to result from a misconception about the role of the gas phase in the ignition process of energetic materials. The model assumes that ignition occurs at the surface and that evolution of gases inhibits ignition. High speed video of laser ignition, oven cook-off and hot wire ignition experiments captures the ignition of HMX and TNT in the gas phase. A laser ignition gap test is performed to further evaluate the effect of gas phase laser absorption and gas phase disruption on the ignition process. Results indicate that gas phase absorption of the laser energy is probably not the primary factor governing the gas phase ignition observations. It is discovered that a critical gap between an HMX pellet and a salt window of 6mm±0.4mm exists below which ignition by CO2 laser is not possible at the tested irradiances of 29W /cm2 and 38W/cm2 for HMX ignition. These observations demonstrate that a significant disruption of the gas phase, in certain scenarios, will inhibit ignition, independent of any condensed phase processes. These results underscore the importance of gas phase processes and illustrate that conditions can exist where simple condensed phase models are inadequate to accurately predict the behavior of energetic materials.

  5. Axial Dispersion and Back-mixing of Gas Phase in Pebble Bed Reactor

    Directory of Open Access Journals (Sweden)

    Rahman Al-Musafir

    2013-04-01

    Full Text Available Despite the worldwide attended of pebble bed reactors (PBRs, there is a lack of fundamental understanding of the complex flow pattern. In this work, the non-ideal flow behavior of the gas phase which is used for cooling has been investigated experimentally in a 0.3 m diameter pebble bed. The extent of mixing and dispersion of the gas phase has been qualified. The effect of gas velocity on the axial dispersion has been investigated with range from 0.05 to 0.6 m/s covering both the laminar and turbulent flow regimes. Glass bead particles of 1.2 cm diameter and 2.5 gm/cm3 which is randomly and closely packed have been used to mimic the pebbles. An advanced gas tracer technique was applied to measure the residence time distribution (RTD of gas phase using impulse tracer. The axial dispersion coefficients of gas phase in the studied pebble bed have been estimated using the axial dispersion model (ADM. It was found that the flow pattern of the gas phase deviates from plug flow depending on the superficial gas velocity. The results showed that the dispersion of the gas reduces as the gas velocity and Reynolds numbers increased.

  6. Task 21 - Field Demonstration of Ex-Situ Biological Treatability of Contaminated Groundwater at the Strachan Gas Plant

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Recognizing the potential impacts of sour gas plant operations on the subsurface environment, the Canadian Association of Petroleum Producers (CAPP), formerly the Canadian Petroleum Association (CPA), and Environment Canada initiated a multiphase study focusing on research related to the development and demonstration of remedial technologies for soil and groundwater contamination at these facilities.

  7. Gas-Phase Combustion Synthesis of Aluminum Nitride Powder

    Science.gov (United States)

    Axelbaum, R. L.; Lottes, C. R.; Huertas, J. I.; Rosen, L. J.

    1996-01-01

    Due to its combined properties of high electrical resistivity and high thermal conductivity aluminum nitride (AlN) is a highly desirable material for electronics applications. Methods are being sought for synthesis of unagglomerated, nanometer-sized powders of this material, prepared in such a way that they can be consolidated into solid compacts having minimal oxygen content. A procedure for synthesizing these powders through gas-phase combustion is described. This novel approach involves reacting AlCl3, NH3, and Na vapors. Equilibrium thermodynamic calculations show that 100% yields can be obtained for these reactants with the products being AlN, NaCl, and H2. The NaCl by-product is used to coat the AlN particles in situ. The coating allows for control of AlN agglomeration and protects the powders from hydrolysis during post-flame handling. On the basis of thermodynamic and kinetic considerations, two different approaches were employed to produce the powder, in co-flow diffusion flame configurations. In the first approach, the three reactants were supplied in separate streams. In the second, the AlCl3 and NH3 were premixed with HCl and then reacted with Na vapor. X-ray diffraction (XRD) spectra of as-produced powders show only NaCl for the first case and NaCl and AlN for the second. After annealing at 775 C tinder dynamic vacuum, the salt was removed and XRD spectra of powders from both approaches show only AlN. Aluminum metal was also produced in the co-flow flame by reacting AlCl3 with Na. XRD spectra of as-produced powders show the products to be only NaCl and elemental aluminum.

  8. Engineered Materials for Advanced Gas Turbine Engine, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop innovative composite powders and composites that will surpass the properties of currently identified materials for advanced gas turbine...

  9. Local anti-correlation between star-formation rate and gas-phase metallicity in disk galaxies

    Science.gov (United States)

    Sánchez Almeida, J.; Caon, N.; Muñoz-Tuñón, C.; Filho, M.; Cerviño, M.

    2018-02-01

    Using a representative sample of 14 star-forming dwarf galaxies in the local Universe, we show the existence of a spaxel-to-spaxel anti-correlation between the index N2 ≡ log ([NII]λ6583/Hα) and the Hα flux. These two quantities are commonly employed as proxies for gas-phase metallicity and star formation rate (SFR), respectively. Thus, the observed N2 to Hα relation may reflect the existence of an anti-correlation between the metallicity of the gas forming stars and the SFR it induces. Such an anti-correlation is to be expected if variable external metal-poor gas fuels the star-formation process. Alternatively, it can result from the contamination of the star-forming gas by stellar winds and SNe, provided that intense outflows drive most of the metals out of the star-forming regions. We also explore the possibility that the observed anti-correlation is due to variations in the physical conditions of the emitting gas, other than metallicity. Using alternative methods to compute metallicity, as well as previous observations of HII regions and photoionization models, we conclude that this possibility is unlikely. The radial gradient of metallicity characterizing disk galaxies does not produce the correlation either.

  10. CO2 Capture from Flue Gas by Phase Transitional Absorption

    Energy Technology Data Exchange (ETDEWEB)

    Liang Hu

    2009-06-30

    A novel absorption process called Phase Transitional Absorption was invented. What is the Phase Transitional Absorption? Phase Transitional Absorption is a two or multi phase absorption system, CO{sub 2} rich phase and CO{sub 2} lean phase. During Absorption, CO{sub 2} is accumulated in CO{sub 2} rich phase. After separating the two phases, CO{sub 2} rich phase is forward to regeneration. After regeneration, the regenerated CO{sub 2} rich phase combines CO{sub 2} lean phase to form absorbent again to complete the cycle. The advantage for Phase Transitional Absorption is obvious, significantly saving on regeneration energy. Because CO{sub 2} lean phase was separated before regeneration, only CO{sub 2} rich phase was forward to regeneration. The absorption system we developed has the features of high absorption rate, high loading and working capacity, low corrosion, low regeneration heat, no toxic to environment, etc. The process evaluation shows that our process is able to save 80% energy cost by comparing with MEA process.

  11. Experimental study of three-phase gas-lift

    NARCIS (Netherlands)

    Descamps, M.N.

    2007-01-01

    The gas-lift technique is a gravity-based pumping technique used for recovering oil from a production well. Gas injected at the bottom of the production pipe reduces the gravity component of the pressure drop and thereby, stimulates the supply of oil from the reservoir. This results in an enhanced

  12. EVALUATION OF A METHOD USING COLLOIDAL GAS APHRONS TO REMEDIATE METALS-CONTAMINATED MINE DRAINAGE WATERS

    Energy Technology Data Exchange (ETDEWEB)

    R. Williams Grimes

    2002-06-01

    Experiments were conducted in which three selected metals-contaminated mine drainage water samples were treated by chemical precipitation followed by flotation using colloidal gas aphrons (CGAs) to concentrate the precipitates. Drainage water samples used in the experiments were collected from an abandoned turn-of-the-century copper mine in south-central Wyoming, an inactive gold mine in Colorado's historic Clear Creek mining district, and a relatively modern gold mine near Rapid City, South Dakota. The copper mine drainage sample was nearly neutral (pH 6.5) while the two gold mine samples were quite acidic (pH {approx}2.5). Metals concentrations ranged from a few mg/L for the copper mine drainage to several thousand mg/L for the sample from South Dakota. CGAs are emulsions of micrometer-sized soap bubbles generated in a surfactant solution. In flotation processes the CGA microbubbles provide a huge interfacial surface area and cause minimal turbulence as they rise through the liquid. CGA flotation can provide an inexpensive alternative to dissolved air flotation (DAF). The CGA bubbles are similar in size to the bubbles typical of DAF. However, CGAs are generated at ambient pressure, eliminating the need for compressors and thus reducing energy, capital, and maintenance costs associated with DAF systems. The experiments involved precipitation of dissolved metals as either hydroxides or sulfides followed by flotation. The CGAs were prepared using a number of different surfactants. Chemical precipitation followed by CGA flotation reduced contaminant metals concentrations by more than 90% for the copper mine drainage and the Colorado gold mine drainage. Contaminant metals were concentrated into a filterable sludge, representing less than 10% of the original volume. CGA flotation of the highly contaminated drainage sample from South Dakota was ineffective. All of the various surfactants used in this study generated a large sludge volume and none provided a

  13. Single phase and two phase erosion corrosion in broilers of gas-cooled reactors

    International Nuclear Information System (INIS)

    Harrison, G.S.; Fountain, M.J.

    1988-01-01

    Erosion-corrosion is a phenomenon causing metal wastage in a variety of locations in water and water-steam circuits throughout the power generation industry. Erosion-corrosion can occur in a number of regions of the once-through boiler designs used in the later Magnox and AGR type of gas cooled nuclear reactor. This paper will consider two cases of erosion-corrosion damage (single and two phase) in once through boilers of gas cooled reactors and will describe the solutions that have been developed. The single phase problem is associated with erosion-corrosion damage of mild steel downstream of a boiler inlet flow control orifice. With metal loss rates of up to 1 mm/year at 150 deg. C and pH in the range 9.0-9.4 it was found that 5 μg/kg oxygen was sufficient to reduce erosion-corrosion rates to less than 0.02 mm/year. A combined oxygen-ammonia-hydrazine feedwater regime was developed and validated to eliminate oxygen carryover and hence give protection from stress corrosion in the austenitic section of the AGR once through boiler whilst still providing erosion-corrosion control. Two phase erosion-corrosion tube failures have occurred in the evaporator of the mild steel once through boilers of the later Magnox reactors operating at pressures in the range 35-40 bar. Rig studies have shown that amines dosed in the feedwater can provide a significant reduction in metal loss rates and a tube lifetime assessment technique has been developed to predict potential tube failure profiles in a fully operational boiler. The solutions identified for both problems have been successfully implemented and the experience obtained following implementation including any problems or other benefits arising from the introduction of the new regimes will be presented. Methods for monitoring and evaluating the efficiency of the solutions have been developed and the results from these exercises will also be discussed. Consideration will also be given to the similarities in the metal loss

  14. Reactions of molecular dications in the gas phase

    International Nuclear Information System (INIS)

    Tafadar, Nurun Nabi

    2001-01-01

    This thesis presents the results from a series of experiments investigating the reactivity of gas phase molecular dications with neutral collision partners, at collision energies between 3 and 13 eV in the laboratory frame using a crossed-beam apparatus. The experiments involve measurement of product ion intensities, which are determined by means of time of flight mass spectrometry. The experimental methodology, together with relevant theory is described in the thesis. The relative intensities of product ions formed are a powerful probe of the reaction mechanism. Where appropriate, the reactions are examined for isotope effects by using the isotopic analogue of the neutral collision partner. Our investigation of the CF 3 2+ /Ar collision system shows neutral loss and electron transfer dominating the product ion yield. The variation of the neutral loss ion yield with collision energy provides a first estimate of the bond energy of the weak CF 2 2+ -F bond. Ab initio calculations indicate the ground state of CF 3 2+ adopts a C 2V equilibrium geometry. We further conclude that at least two electronic states of CF 3 2+ are present in the dication beam. Intramolecular isotope effects in the reactions of CO 2 2+ and CF 3 2+ with HD indicate the operation of an intramolecular isotope effect, favouring the formation of the deuterated products DCF 2 + and DCO + . However, for the CF 3 2+ /HD system our data reveals no isotope effect for the formation of HF + and the DF + within our experimental uncertainty. Statistical effects have been suggested as an alternative to the orientational model previously used to explain these effects. In our investigation of the CF 3 2+ /H 2 /D 2 and CO 2 2+ /H 2 /D 2 collision systems, experiments indicate that no intermolecular effects are in operation and the observed collision energy dependence is symptomatic of the absence of a barrier to reaction. In the CF 3 2+ /H 2 /D 2 system we observe the formation of the XF + product ion; a

  15. Towards a Quantitative Framework for Evaluating Vulnerability of Drinking Water Wells to Contamination from Unconventional Oil & Gas Development

    Science.gov (United States)

    Soriano, M., Jr.; Deziel, N. C.; Saiers, J. E.

    2017-12-01

    The rapid expansion of unconventional oil and gas (UO&G) production, made possible by advances in hydraulic fracturing (fracking), has triggered concerns over risks this extraction poses to water resources and public health. Concerns are particularly acute within communities that host UO&G development and rely heavily on shallow aquifers as sources of drinking water. This research aims to develop a quantitative framework to evaluate the vulnerability of drinking water wells to contamination from UO&G activities. The concept of well vulnerability is explored through application of backwards travel time probability modeling to estimate the likelihood that capture zones of drinking water wells circumscribe source locations of UO&G contamination. Sources of UO&G contamination considered in this analysis include gas well pads and documented sites of UO&G wastewater and chemical spills. The modeling approach is illustrated for a portion of Susquehanna County, Pennsylvania, where more than one thousand shale gas wells have been completed since 2005. Data from a network of eight multi-level groundwater monitoring wells installed in the study site in 2015 are used to evaluate the model. The well vulnerability concept is proposed as a physically based quantitative tool for policy-makers dealing with the management of contamination risks of drinking water wells. In particular, the model can be used to identify adequate setback distances of UO&G activities from drinking water wells and other critical receptors.

  16. Gas treatment of Cr(VI)-contaminated sediment samples from the North 60's pits of the chemical waste landfill

    International Nuclear Information System (INIS)

    Thornton, E.C.; Amonette, J.E.

    1997-12-01

    Twenty sediment samples were collected at depths ranging from 5 to 100 ft (1.5 to 30 m) beneath a metal-contaminated plating-waste site and extensively characterized for Cr(VI) content and environmental availability. Three samples were selected for treatment with diluted gas mixtures with the objective of converting Cr(VI) to Cr(III), which is relatively nontoxic and immobile. These tests were designed to provide information needed to evaluate the potential application of gas injection as an in situ remediation technique. Gas treatment was performed in small columns (4.9-cm ID, 6.4- to 13.9-cm long) using 100 ppm (μL L -1 ) H 2 S or ethylene mixtures in N 2 . Treatment progress during the tests involving H 2 S was assessed by monitoring the breakthrough of H 2 S. Evaluation of H 2 S treatment efficacy included (1) water-leaching of treated and untreated columns for ten days, (2) repetitive extraction of treated and untreated subsamples by water, 0.01 M phosphate (pH 7) or 6 M HCl solutions, and (3) Cr K-edge X-ray absorption near-edge structure (XANES) spectroscopy of treated and untreated subsamples. Results of the water-leaching studies showed that the H 2 S treatment decreased Cr(VI) levels in the column effluent by 90% to nearly 100%. Repetitive extractions by water and phosphate solutions echoed these results, and the extraction by HCl released only 35-40% as much Cr in the treated as in the untreated samples. Analysis by XANES spectroscopy showed that a substantial portion of the Cr in the samples remained as Cr(VI) after treatment, even though it was not available to the water and phosphate extracting solutions. These results suggest that this residual Cr(VI) is present in low solubility phases such as PbCrO 4 or sequestered in unreacted grain interiors under impermeable coatings formed during H 2 S treatment. However, this fraction is essentially immobile and thus unavailable to the environment

  17. Mobile Passive Optical Imager for Remote Gas Detection, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Tunable filters based on electro-optic effect have shown great potential in detecting gas concentration through obtaining its absorption spectrum. In filter-based...

  18. Highly Efficient Electrochemical Cryogenic Purge Gas Recovery System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Ongoing rocket test operations at NASA Stennis Space Center (SSC) result in substantial quantities of hydrogen gas that is flared from the facility in addition to...

  19. Hot Gas TVC For Planetary Ascent Vehicle, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A Mars ascent vehicle (MAV) uses solid rocket motors to propel soil samples into orbit, but the motors cannot provide steering. Cold gas thrusters are used for...

  20. Advanced On Board Inert Gas Generation System (OBBIGS), Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Valcor Engineering Corporation proposes to develop an advanced On Board Inert Gas Generation System, OBIGGS, for aircraft fuel tank inerting to prevent hazardous...

  1. Advanced Gas Sensing Technology for Space Suits, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The gas sensor in the PLSS of the ISS EMU will meet its projected life in 2020, and NASA is planning to replace it. At present, only high TRL devices based on...

  2. Compact Sensor for Isotope and Trace Gas Analysis, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop and demonstrate a new sensor platform for isotope and trace-gas analysis that is appropriate for future planetary missions. Among other...

  3. Compact, Robust, Low Power High Sensitivity Gas Sensor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Miniaturized gas sensors with high sensitivity that are compact, low power and low weight are needed to support for NASA's airborne science missions, particularly...

  4. Advanced On Board Inert Gas Generation System (OBBIGS), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Valcor Engineering Corporation proposes to develop an advanced On Board Inert Gas Generation System, OBIGGS, for aircraft fuel tank inerting to prevent hazardous...

  5. Two-stage coal liquefaction without gas-phase hydrogen

    Science.gov (United States)

    Stephens, H.P.

    1986-06-05

    A process is provided for the production of a hydrogen-donor solvent useful in the liquefaction of coal, wherein the water-gas shift reaction is used to produce hydrogen while simultaneously hydrogenating a donor solvent. A process for the liquefaction of coal using said solvent is also provided. The process enables avoiding the use of a separate water-gas shift reactor as well as high pressure equipment for liquefaction. 3 tabs.

  6. Local gas- and liquid-phase measurements for air-water two-phase flows in a rectangular channel

    International Nuclear Information System (INIS)

    Zhou, X.; Sun, X.; Williams, M.; Fu, Y.; Liu, Y.

    2014-01-01

    Local gas- and liquid-phase measurements of various gas-liquid two-phase flows, including bubbly, cap-bubbly, slug, and churn-turbulent flows, were performed in an acrylic vertical channel with a rectangular cross section of 30 mm x 10 mm and height of 3.0 m. All the measurements were carried out at three measurement elevations along the flow channel, with z/D h = 9, 72, and 136, respectively, to study the flow development. The gas-phase velocity, void fraction, and bubble number frequency were measured using a double-sensor conductivity probe. A high-speed imaging system was utilized to perform the flow regime visualization and to provide additional quantitative information of the two-phase flow structure. An image processing scheme was developed to obtain the gas-phase velocity, void fraction, Sauter mean diameter, bubble number density, and interfacial area concentration. The liquid-phase velocity and turbulence measurements were conducted using a particle image velocimetry-planar laser-induced fluorescence (PIV-PLIF) system, which enables whole-field and high-resolution data acquisition. An optical phase separation method, which uses fluorescent particles and optical filtration technique, is adopted to extract the velocity information of the liquid phase. An image pre-processing scheme is imposed on the raw PIV images acquired to remove noises due to the presence of bubble residuals and optically distorted particles in the images captured by the PIV-PLIF system. Due to the better light access and less bubble distortion in the narrow rectangular channel, the PIV-PLIF system were able to perform reasonably well in flows of even higher void fractions as compared to the situations with circular pipe test sections. The flow conditions being studied covered various flow regime transitions, void fractions, and liquid-phase flow Reynolds numbers. The obtained experimental data can also be used to validate two-phase CFD results. (author)

  7. Reason analysis for contamination of protective clothes during the first outage of unit 1 at Qinshan Nuclear Power Plant phase II

    International Nuclear Information System (INIS)

    Wang Chuan; Wang Dezhong; Zheng Weiyan

    2007-01-01

    More contamination events of protective clothes were occurred during the first outage of Unit 1 at Qinshan Nuclear Power Plant phase II. As a result, contaminated protective clothes were accumulated. This paper describes the amount and conditions of protective clothes analyses and discussies the reason of contamination. The measures for protecting protective clothes agaist contamination were put forward. (authors)

  8. Crystal-liquid-gas phase transitions and thermodynamic similarity

    CERN Document Server

    Skripov, Vladimir P; Schmelzer, Jurn W P

    2006-01-01

    Professor Skripov obtained worldwide recognition with his monograph ""Metastable liquids"", published in English by Wiley & Sons. Based upon this work and another monograph published only in Russia, this book investigates the behavior of melting line and the properties of the coexisting crystal and liquid phase of simple substances across a wide range of pressures, including metastable states of the coexisting phases. The authors derive new relations for the thermodynamic similarity for liquid-vapour phase transition, as well as describing solid-liquid, liquid-vapor and liquid-liquid phase tra

  9. Enhanced Membrane System for Recovery of Water from Gas-Liquid Mixtures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Gas-Liquid separation is an acute microgravity problem. Existing devices use centrifugal motion on microporous membranes to separate the two phases. Centrifugal...

  10. Fluorescence resonance energy transfer of gas-phase ions under ultra high vacuum and ambient conditions.

    Science.gov (United States)

    Frankevich, Vladimir; Chagovets, Vitaliy; Widjaja, Fanny; Barylyuk, Konstantin; Yang, Zhiyi; Zenobi, Renato

    2014-05-21

    We report evidence for fluorescence resonance energy transfer (FRET) of gas-phase ions under ultra high vacuum conditions (10(-9) mbar) inside a mass spectrometer as well as under ambient conditions inside an electrospray plume. Two different FRET pairs based on carboxyrhodamine 6G (donor) and ATTO590 or Bodipy TR (acceptor) dyes were examined and their gas-phase optical properties were studied. Our measurements indicate a different behavior for the two FRET pairs, which can be attributed to their different conformations in the gas phase. Upon desolvation via electrospray ionization, one of the FRET pairs undergoes a conformational change that leads to disappearance of FRET. This study shows the promise of FRET to obtain a direct correlation between solution and gas-phase structures.

  11. Mobile Greenhouse Gas Flux Analyzer for Unmanned Aerial Vehicles, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In this SBIR Phase I effort, Los Gatos Research (LGR) proposes to develop a highly-accurate, lightweight, low-power gas analyzer for eddy flux covariance...

  12. Mononuclear metavanadate catalyses gas phase oxidation of methanol to formaldehyde employing dioxygen as the terminal oxidant.

    Science.gov (United States)

    Waters, Tom; Khairallah, George N; Wimala, Samantha A S Y; Ang, Yien C; O'Hair, Richard A J; Wedd, Anthony G

    2006-11-21

    Multistage mass spectrometry experiments reveal a sequence of gas phase reactions for the oxidation of methanol to formaldehyde with a mononuclear oxo vanadate anion as the catalyst and dioxygen as the terminal oxidant.

  13. Gas-Kinetic Computational Algorithms for Hypersonic Flows in Continuum and Transitional Regimes, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project explores two gas-kinetic computational algorithms for simulation of hypersonic flows in both continuum and transitional regimes. One is the...

  14. Gas-phase water-mediated equilibrium between methylglyoxal and its geminal diol

    Science.gov (United States)

    Axson, Jessica L.; Takahashi, Kaito; De Haan, David O.; Vaida, Veronica

    2010-01-01

    In aqueous solution, aldehydes, and to a lesser extent ketones, hydrate to form geminal diols. We investigate the hydration of methylglyoxal (MG) in the gas phase, a process not previously considered to occur in water-restricted environments. In this study, we spectroscopically identified methylglyoxal diol (MGD) and obtained the gas-phase partial pressures of MG and MGD. These results, in conjunction with the relative humidity, were used to obtain the equilibrium constant, KP, for the water-mediated hydration of MG in the gas phase. The Gibbs free energy for this process, ΔG°, obtained as a result, suggests a larger than expected gas-phase diol concentration. This may have significant implications for understanding the role of organics in atmospheric chemistry. PMID:20142510

  15. Separation of Flue Gas Components by SILP (Supported Ionic Liquid-Phase) Absorbers

    DEFF Research Database (Denmark)

    Thomassen, P.; Kunov-Kruse, Andreas Jonas; Mossin, Susanne L.

    2013-01-01

    . The results show that CO2, NO and SO2 can be reversible and selective absorbed using different ILs and that Supported Ionic Liquid-Phase (SILP) absorbers are promising materials for industrial flue gas cleaning. Absorption/desorption dynamics can be tuned by temperature, pressure and gas concentration. © 2012......Reversible absorption of the flue gas components CO2, NO, NO2 and SO2 has been tested for different ionic liquids (ILs) at different temperatures and flue gas compositions where porous, high surface area carriers have been applied as supports for the ionic liquids to obtain Supported Ionic Liquid......-Phase (SILP) absorber materials. The use of solid SILP absorbers with selected ILs were found to significantly improve the absorption capacity and sorption dynamics at low flue gas concentration, thus making the applicability of ILs viable in technical, continuous flow processes for flue gas cleaning...

  16. Determination of gas phase triacetone triperoxide with aspiration ion mobility spectrometry and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Räsänen, Riikka-Marjaana; Nousiainen, Marjaana; Peräkorpi, Kaleva; Sillanpää, Mika; Polari, Lauri; Anttalainen, Osmo; Utriainen, Mikko

    2008-08-08

    Aspiration ion mobility spectrometry (IMS) has been used for the first time to screen 3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexaoxacyclononane explosive, the most commonly known as triacetone triperoxide (TATP). Gaseous TATP was generated from synthesized solid compound, sublimed and directed to a portable chemical detection system comprised of an aspiration-type IMS detector and six semiconductor sensors. Different unknown TATP gas phase concentrations were produced and corresponding IMS and semiconductor responses were measured. The experimental concentrations were determined by gas chromatography-mass spectrometry (GC-MS). The results evidenced that the monitored compound in the gas phase was TATP. In addition, the determined TATP concentrations and corresponding IMS intensities showed that the IMS response values were proportional to the measured TATP concentrations.

  17. Gas phase ion/molecule reactions as studied by Fourier Transform Ion Cyclotron Resonance mass spectrometry

    International Nuclear Information System (INIS)

    Joergensen, S.I.

    1985-01-01

    The subject of this thesis is gas phase ion/molecule reactions as studied by Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometry (chapter 2 contains a short description of this method). Three chapters are mainly concerned with mechanistic aspects of gas phase ion/molecule reactions. An equally important aspect of the thesis is the stability and reactivity of α-thio carbanions, dipole stabilized carbanions and homoenolate anions, dealt with in the other four chapters. (Auth.)

  18. Defect formation in fluoropolymer films at their condensation from a gas phase

    Science.gov (United States)

    Luchnikov, P. A.

    2018-01-01

    The questions of radiation defects, factors of influence of electronic high-frequency discharge plasma components on the molecular structure and properties of the fluoropolymer vacuum films synthesized on a substrate from a gas phase are considered. It is established that at sedimentation of fluoropolymer coverings from a gas phase in high-frequency discharge plasma in films there are radiation defects in molecular and supramolecular structure because of the influence of active plasma components which significantly influence their main properties.

  19. Gas phase ion chemistry of coumarins: ab initio calculations used to ...

    African Journals Online (AJOL)

    The gas phase ion chemistry of coumarins using electron ionization (EI), positive chemical ionization (PCI) and negative chemical ionization (NCI) in a time of flight and quadrupole mass spectrometer (qMS) coupled to a gas chromatograph is outlined. The observations in NCI mode were complimented with Ab initio ...

  20. Severe slugging in gas-liquid two-phase pipe flow

    NARCIS (Netherlands)

    Malekzadeh, R.

    2012-01-01

    transportation facilities. In an offshore oil and gas production facility, pipeline-riser systems are required to transport two-phase hydrocarbons from subsurface oil and gas wells to a central production platform. Severe slugs reaching several thousands pipe diameters may occur when transporting

  1. Dynamic simulation of dispersed gas-liquid two-phase flow using a discrete bubble model.

    NARCIS (Netherlands)

    Delnoij, E.; Lammers, F.A.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    1997-01-01

    In this paper a detailed hydrodynamic model for gas-liquid two-phase flow will be presented. The model is based on a mixed Eulerian-Lagrangian approach and describes the time-dependent two-dimensional motion of small, spherical gas bubbles in a bubble column operating in the homogeneous regime. The

  2. Optical pyrometer based on the gas phase photoacoustic effect.

    Science.gov (United States)

    Meng, Xiangling; Diebold, Gerald J

    2016-05-15

    A photoacoustic cell containing an infrared active gas and equipped with a pair of infrared transmitting windows that alternately views two bodies at different temperatures through a pair of chopping wheels acts as a differential detector of the radiation emitted by the two bodies. A theory for the photoacoustic signal shows that the device acts to monitor the difference in the incidances between the two bodies integrated over the absorptions of the gas in the cell. Experiments are reported showing that the response of the pyrometer depends on the relative temperatures of heated bodies, the absorption coefficient of the gas in the cell, and the modulation frequency of the chopping wheels. The instrument is shown to be a sensitive detector of a null in the integrated incidance of the two bodies.

  3. Propagation characteristics of pulverized coal and gas two-phase flow during an outburst.

    Science.gov (United States)

    Zhou, Aitao; Wang, Kai; Fan, Lingpeng; Tao, Bo

    2017-01-01

    Coal and gas outbursts are dynamic failures that can involve the ejection of thousands tons of pulverized coal, as well as considerable volumes of gas, into a limited working space within a short period. The two-phase flow of gas and pulverized coal that occurs during an outburst can lead to fatalities and destroy underground equipment. This article examines the interaction mechanism between pulverized coal and gas flow. Based on the role of gas expansion energy in the development stage of outbursts, a numerical simulation method is proposed for investigating the propagation characteristics of the two-phase flow. This simulation method was verified by a shock tube experiment involving pulverized coal and gas flow. The experimental and simulated results both demonstrate that the instantaneous ejection of pulverized coal and gas flow can form outburst shock waves. These are attenuated along the propagation direction, and the volume fraction of pulverized coal in the two-phase flow has significant influence on attenuation of the outburst shock wave. As a whole, pulverized coal flow has a negative impact on gas flow, which makes a great loss of large amounts of initial energy, blocking the propagation of gas flow. According to comparison of numerical results for different roadway types, the attenuation effect of T-type roadways is best. In the propagation of shock wave, reflection and diffraction of shock wave interact through the complex roadway types.

  4. Propagation characteristics of pulverized coal and gas two-phase flow during an outburst

    Science.gov (United States)

    Zhou, Aitao; Wang, Kai; Fan, Lingpeng; Tao, Bo

    2017-01-01

    Coal and gas outbursts are dynamic failures that can involve the ejection of thousands tons of pulverized coal, as well as considerable volumes of gas, into a limited working space within a short period. The two-phase flow of gas and pulverized coal that occurs during an outburst can lead to fatalities and destroy underground equipment. This article examines the interaction mechanism between pulverized coal and gas flow. Based on the role of gas expansion energy in the development stage of outbursts, a numerical simulation method is proposed for investigating the propagation characteristics of the two-phase flow. This simulation method was verified by a shock tube experiment involving pulverized coal and gas flow. The experimental and simulated results both demonstrate that the instantaneous ejection of pulverized coal and gas flow can form outburst shock waves. These are attenuated along the propagation direction, and the volume fraction of pulverized coal in the two-phase flow has significant influence on attenuation of the outburst shock wave. As a whole, pulverized coal flow has a negative impact on gas flow, which makes a great loss of large amounts of initial energy, blocking the propagation of gas flow. According to comparison of numerical results for different roadway types, the attenuation effect of T-type roadways is best. In the propagation of shock wave, reflection and diffraction of shock wave interact through the complex roadway types. PMID:28727738

  5. Assessment of soil-gas, seep, and soil contamination at the North Range Road Landfill, Fort Gordon, Georgia, 2008-2009

    Science.gov (United States)

    Landmeyer, James E.; Falls, W. Fred; Ratliff, W. Hagan; Wellborn, John B.

    2011-01-01

    Soil gas, seeps, and soil were assessed for contaminants at the North Range Road Landfill at Fort Gordon, Georgia, from October 2008 to September 2009. The assessment included delineating organic contaminants present in soil-gas samples beneath the area estimated to be the landfill and in water samples collected from three seeps at the base of the landfill. Inorganic contaminants were determined in three seep samples and in soil samples. This assessment was conducted to provide environmental contamination data to Fort Gordon pursuant to requirements for the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process.

  6. Contamination of the operating room by anesthetic gases and vapors. II. Gas chromatographic analysis of nitrous oxide

    Energy Technology Data Exchange (ETDEWEB)

    Cattaneo, A.D.; Ferraiolo, G.; Rovatti, M.; Zattoni, J.; Donato, A.

    1981-12-01

    The contamination by nitrous oxide of an operating room atmosphere was studied in a number of experiments, in the absence of personnel and using a gaschromatographic method. The evacuating device of the anesthesia machine proved to be ineffective to overcome the hazard of leaks in the breathing system, whereas the air conditioning flow rates (12 outside air changes per hour) minimized waste anesthetic gas concentrations.

  7. Particle contamination in gas-insulated systems: new control methods and optimum SF6/N2 mixtures

    International Nuclear Information System (INIS)

    Pace, M.O.; Adcock, J.L.; Christophorou, L.G.

    1984-01-01

    The feasibilities of two new separate techniques to control particle contamination in practical gas-insulated sytems were tested in a small-scale concentric cylinder geometry. In one technique an insulating coating was first formed on the particles in a contaminated system by low-pressure discharges in appropriate gases such as 1-C 3 F 6 and c-C 4 F 8 . When SF 6 was subsequently introduced into the same system at practical pressure as the operating insulation, the considerable harm ordinarily caused by particles was found to be eliminated. The nature of the coating formed also on the electrodes in this process was studied, with the conclusion that the observed benefits were primarily due to coating on particles, not on electrodes. In the second technique the particles, moved randomly by electrical stress, struck and adhered to the surface of a tacky insulating solid material; they were subsequently encapsulated in a melt-resolidify cycle without electrical stress. This trapping technique was also found to eliminate the harmful effects of particles in SF 6 at practical pressure. A technique for producing a trapping material with temperature characteristics appropriate for practical apparatus was devised. The effect of particle contamination on the dielectric strength of SF 6 /N 2 mixtures was studied as a function of total pressure and percentage of each gas. Optimum total pressure (approx. 6 atm) and optimum percentages (60% SF 6 /40% N 2 ) were observed in breakdown tests in particle-contaminated concentric cylinder geometry

  8. Oriented xenon hydride molecules in the gas phase

    Czech Academy of Sciences Publication Activity Database

    Buck, U.; Fárník, Michal

    2006-01-01

    Roč. 25, č. 4 (2006), s. 583-612 ISSN 0144-235X Grant - others:Deutsche Forschungsgemeinschaft(DE) SFB 357 Institutional research plan: CEZ:AV0Z40400503 Keywords : photofragment translational spectroscopy * charge transfer molecules * low temperature matrices * neutral rare-gas Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.036, year: 2006

  9. Gas phase dispersion in a small rotary kiln

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, B.B.

    1981-07-01

    A study was made of nonideal flow of gas in a rotary kiln reactor. A rotating tube 0.165 m in diameter by 2.17 m long, with internal lifting flights, was operated at room temperature. Rotational speeds from 2.0 to 7.0 rpm, air flow rates from 0.351 to 4.178 m/sup 3//h, and solid contents of 0.0, 5.1, and 15.3% of tube volume were studied. Residence time distribution of the gas was measured by means of the pulse injection technique using a helium tracer. A model was developed based on dispersive flow that exchanges with a deadwater region. Two parameters, a dispersion number describing bulk gas flow and an interchange factor describing exchange between the flow region and the gas trapped in the solids bed, were sufficient to correlate the data, but these parameters are sensitive to experimental error. The model is applicable to analysis of other flow systems, such as packed beds.

  10. Experimental and CFD investigation of gas phase freeboard combustion

    DEFF Research Database (Denmark)

    Andersen, Jimmy

    Reliable and accurate modeling capabilities for combustion systems are valuable tools for optimization of the combustion process. This work concerns primary precautions for reducing NO emissions, thereby abating the detrimental effects known as “acid rain”, and minimizing cost for flue gas...

  11. Gas phase dispersion in a small rotary kiln

    International Nuclear Information System (INIS)

    Spencer, B.B.

    1981-07-01

    A study was made of nonideal flow of gas in a rotary kiln reactor. A rotating tube 0.165 m in diameter by 2.17 m long, with internal lifting flights, was operated at room temperature. Rotational speeds from 2.0 to 7.0 rpm, air flow rates from 0.351 to 4.178 m 3 /h, and solid contents of 0.0, 5.1, and 15.3% of tube volume were studied. Residence time distribution of the gas was measured by means of the pulse injection technique using a helium tracer. A model was developed based on dispersive flow that exchanges with a deadwater region. Two parameters, a dispersion number describing bulk gas flow and an interchange factor describing exchange between the flow region and the gas trapped in the solids bed, were sufficient to correlate the data, but these parameters are sensitive to experimental error. The model is applicable to analysis of other flow systems, such as packed beds

  12. Ceramic stationary gas turbine development. Final report, Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-09-01

    This report summarizes work performed by Solar Turbines Inc. and its subcontractors during the period September 25, 1992 through April 30, 1993. The objective of the work is to improve the performance of stationary gas turbines in cogeneration through implementation of selected ceramic components.

  13. Application of the Vapor-phase Multi-stage CMD Test to Characterize Contaminant Mass Discharge Associated with Volatile Organic Contaminant Sources in the Vadose Zone

    Science.gov (United States)

    Brusseau, M. L.; Mainhagu, J.; Morrison, C. N.; Carroll, K. C.

    2014-12-01

    Vapor-phase multi-stage contaminant mass discharge (CMD) tests were conducted at two field sites to measure mass discharge associated with contaminant sources located in the vadose zone. A CMD of 32 g/d was obtained for a site at which soil vapor extraction (SVE) has been in operation for approximately 6 years. The behavior exhibited for the vapor extractions conducted at this site suggests that there is unlikely to be a significant mass of non-vapor-phase contaminant (e.g., DNAPL, sorbed phase) present in the advective domains, and that most remaining mass is likely located in poorly accessible domains. Given the conditions for this site, this remaining mass is hypothesized to be associated with the low-permeability (and higher water saturation) region in the vicinity of the saturated zone and capillary fringe. This is supported by the results of a sediment-coring effort conducted prior to the CMD test. A CMD of 270 g/d was obtained for a site for which there were no prior SVE operations. The behavior exhibited for the vapor extractions conducted at this site suggest that non-vapor-phase contaminant mass (e.g., DNAPL) may be present in the advective domains. This is consistent with the results of prior characterization activities conducted at the site. Hence, the asymptotic conditions observed for this site most likely derive from a combination of rate-limited mass transfer from DNAPL (and sorbed) phases present in the advective domain as well as mass residing in lower-permeability ("non-advective") regions. The CMD values obtained from the tests were used in conjunction with a recently developed vapor-discharge tool to evaluate the impact of the measured CMDs on groundwater quality.

  14. Visualization of velocity field and phase distribution in gas-liquid two-phase flow by NMR imaging

    International Nuclear Information System (INIS)

    Matsui, G.; Monji, H.; Obata, J.

    2004-01-01

    NMR imaging has been applied in the field of fluid mechanics, mainly single phase flow, to visualize the instantaneous flow velocity field. In the present study, NMR imaging was used to visualize simultaneously both the instantaneous phase structure and velocity field of gas-liquid two-phase flow. Two methods of NMR imaging were applied. One is useful to visualize both the one component of liquid velocity and the phase distribution. This method was applied to horizontal two-phase flow and a bubble rising in stagnant oil. It was successful in obtaining some pictures of velocity field and phase distribution on the cross section of the pipe. The other is used to visualize a two-dimensional velocity field. This method was applied to a bubble rising in a stagnant water. The velocity field was visualized after and before the passage of a bubble at the measuring cross section. Furthermore, the distribution of liquid velocity was obtained. (author)

  15. Industrial fuel gas demonstration plant program. Current working estimate. Phase III and III

    Energy Technology Data Exchange (ETDEWEB)

    1979-12-01

    The United States Department of Energy (DOE) executed a contract with Memphis Light, Gas and Water Division (MLGW) which requires MLGW to perform process analysis, design, procurement, construction, testing, operation, and evaluation of a plant which will demonstrate the feasibility of converting high sulfur bituminous coal to industrial fuel gas with a heating value of 300 +- 30 Btu per standard cubic foot (SCF). The demonstration plant is based on the U-Gas process, and its product gas is to be used in commercial applications in Memphis, Tenn. The contract specifies that the work is to be conducted in three phases. The Phases are: Phase I - Program Development and Conceptual Design; Phase II - Demonstration Plant Final Design, Procurement and Construction; and Phase III - Demonstration Plant Operation. Under Task III of Phase I, a Cost Estimate for the Demonstration Plant was completed as well as estimates for other Phase II and III work. The output of this Estimate is presented in this volume. This Current Working Estimate for Phases II and III is based on the Process and Mechanical Designs presented in the Task II report (second issue) and the 12 volumes of the Task III report. In addition, the capital cost estimate summarized in the appendix has been used in the Economic Analysis (Task III) Report.

  16. Gas distribution equipment in hydrogen service - Phase II

    Science.gov (United States)

    Jasionowski, W. J.; Huang, H. D.

    1980-01-01

    The hydrogen permeability of three different types of commercially available natural gas polyethylene pipes was determined. Ring tensile tests were conducted on permeability-exposed and as-received samples. Hydrogen-methane leakage experiments were also performed. The results show no selective leakage of hydrogen via Poiseuille, turbulent, or orifice flow (through leaks) on the distribution of blends of hydrogen and methane. The data collected show that the polyethylene pipe is 4 to 6 times more permeable to hydrogen than to methane.

  17. A gas-phase source term for Yucca Mountain

    International Nuclear Information System (INIS)

    Zwahlen, E.D.; Lee, W.W.L.; Pigford, T.H.; Chambre, P.L.

    1990-02-01

    We previously presented analyses of gas flow into and out of a partly failed nuclear waste container for various assumed hole sizes and failure times. We also estimated the release rate of 14 C by advection and counter-diffusion from the failed container. Here we present an estimate of 14 C release rate and cumulative release for hole sizes of one to 300-μm and failure at emplacement and 300 years. 4 refs., 4 figs

  18. Multiscale and luminescent, hollow microspheres for gas phase thermometry

    OpenAIRE

    Bischoff, Lothar; Stephan, Michael; Birkel, Christina S.; Litterscheid, Christian F.; Dreizler, Andreas; Albert, Barbara

    2018-01-01

    Recently developed laser-based measurement techniques are used to image the temperatures and velocities in gas flows. They require new phosphor materials with an unprecedented combination of properties. A novel synthesis procedure is described here; it results in hierarchically structured, hollow microspheres of Eu3+-doped Y2O3, with unusual particle sizes and very good characteristics compared to full particles. Solution-based precipitation on polymer microballoons produces very stable and l...

  19. Analysis of volatile phase transport in soils using natural radon gas as a tracer

    International Nuclear Information System (INIS)

    Chen, C.; Thomas, D.M.

    1992-01-01

    We have conducted a field study of soil gas transport processes using radon gas as a naturally occurring tracer. The experiment monitored soil gas radon activity, soil moisture, and soil temperature at three depths in the shallow soil column; barometric pressure, rainfall and wind speed were monitored at the soil surface. Linear and multiple regression analysis of the data sets has shown that the gas phase radon activities under natural environmental conditions are influenced by soil moisture content, barometric pressure variations, soil temperature and soil structure. The effect of wind speed on subsurface radon activities under our field conditions has not been demonstrated

  20. Modeling contaminant transport in a three-phase groundwater system with the Freundlich-type retardation factor.

    Science.gov (United States)

    Kim, M; Kim, S B

    2007-02-01

    Colloid-facilitated contaminant transport was simulated in this study for the three-phase groundwater system where one or more sorption processes can be described with nonlinear sorption isotherm (Freundlich isotherm). A concise form of contaminant transport equation was derived from the mass balance equation of the contaminant. The developed model was numerically solved by the finite difference method along with the Picard iteration. The simulation results were used to quantitatively analyze the previously reported column data showing nonlinear sorption behavior. The analysis led to the following observations: (i) increases of the distribution coefficient of contaminant between the aqueous and solid phases (K(S)c) and the one between the dissolved natural organic matters and solid phase ( K(S)OM) generate less facilitation (i.e., late arrival of contaminant breakthrough curves (BTCs), and the distribution coefficient of contaminant between the aqueous and the solid phases (K(OM)c) gives the opposite result; (ii) the increase of the Freundlich constant for the sorption isotherm between the aqueous and the solid phases (N(S)c) yields the late arrival of BTC, and the other two Freundlich constants produce the opposite results; (iii) the Freundlich constants generally yield a sharper front as the BTC arrives at later pore volumes, while the distribution coefficients generally yield a more spread of the BTC as it arrives at later volumes. This modeling study shows that transport modeling provides a more efficient analyzing tool than the retardation factor alone concerning the colloid-facilitated contaminant transport with nonlinear sorption processes.

  1. Endocrine-Disrupting Chemicals and Oil and Natural Gas Operations: Potential Environmental Contamination and Recommendations to Assess Complex Environmental Mixtures.

    Science.gov (United States)

    Kassotis, Christopher D; Tillitt, Donald E; Lin, Chung-Ho; McElroy, Jane A; Nagel, Susan C

    2016-03-01

    Hydraulic fracturing technologies, developed over the last 65 years, have only recently been combined with horizontal drilling to unlock oil and gas reserves previously deemed inaccessible. Although these technologies have dramatically increased domestic oil and natural gas production, they have also raised concerns for the potential contamination of local water supplies with the approximately 1,000 chemicals that are used throughout the process, including many known or suspected endocrine-disrupting chemicals. We discuss the need for an endocrine component to health assessments for drilling-dense regions in the context of hormonal and antihormonal activities for chemicals used. We discuss the literature on a) surface and groundwater contamination by oil and gas extraction operations, and b) potential human exposure, particularly in the context of the total hormonal and antihormonal activities present in surface and groundwater from natural and anthropogenic sources; we also discuss initial analytical results and critical knowledge gaps. In light of the potential for environmental release of oil and gas chemicals that can disrupt hormone receptor systems, we recommend methods for assessing complex hormonally active environmental mixtures. We describe a need for an endocrine-centric component for overall health assessments and provide information supporting the idea that using such a component will help explain reported adverse health trends as well as help develop recommendations for environmental impact assessments and monitoring programs.

  2. Endocrine-disrupting chemicals and oil and natural gas operations: Potential environmental contamination and recommendations to assess complex environmental mixtures

    Science.gov (United States)

    Kassotis, Christopher D.; Tillitt, Donald E.; Lin, Chung-Ho; McElroy, Jane A.; Nagel, Susan C.

    2016-01-01

    Background: Hydraulic fracturing technologies, developed over the last 65 years, have only recently been combined with horizontal drilling to unlock oil and gas reserves previously deemed inaccessible. While these technologies have dramatically increased domestic oil and natural gas production, they have also raised concerns for the potential contamination of local water supplies with the approximately 1,000 chemicals used throughout the process, including many known or suspected endocrine-disrupting chemicals.Objectives: We discuss the need for an endocrine component to health assessments for drilling-dense regions in the context of hormonal and anti-hormonal activities for chemicals used.Methods: We discuss the literature on 1) surface and ground water contamination by oil and gas extraction operations, and 2) potential human exposure, particularly in context of the total hormonal and anti-hormonal activities present in surface and ground water from natural and anthropogenic sources, with initial analytical results and critical knowledge gaps discussed.Discussion: In light of the potential for environmental release of oil and gas chemicals that can disrupt hormone receptor systems, we recommend methods for assessing complex hormonally active environmental mixtures.Conclusions: We describe a need for an endocrine-centric component for overall health assessments and provide supporting information that using this may help explain reported adverse health trends as well as help develop recommendations for environmental impact assessments and monitoring programs.

  3. CASCADER: An m-chain gas-phase radionuclide transport and fate model

    International Nuclear Information System (INIS)

    Cawlfield, D.E.; Been, K.B.; Emer, D.F.; Lindstrom, F.T.; Shott, G.J.

    1993-06-01

    Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and/or diffusion. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. This is volume two to the CASCADER series, titled CASCADR8. It embodies the concepts presented in volume one of this series. To properly understand how the CASCADR8 model works, the reader should read volume one first. This volume presents the input and output file structure for CASCADR8, and a set of realistic scenarios for buried sources of radon gas

  4. CASCADER: An M-chain gas-phase radionuclide transport and fate model

    International Nuclear Information System (INIS)

    Cawlfield, D.E.; Emer, D.F.; Lindstrom, F.T.; Shott, G.J.

    1993-09-01

    Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and/or dispersion. Additionally during the transport of parent and daughter radionuclides in soil, radionuclide decay may occur. This version of CASCADER called CASCADR9 starts with the concepts presented in volumes one and three of this series. For a proper understanding of how the model works, the reader should read volume one first. Also presented in this volume is a set of realistic scenarios for buried sources of radon gas, and the input and output file structure for CASCADER9

  5. The electron spectrum of UF6 recorded in the gas phase

    Science.gov (United States)

    Mârtensson, N.; Malmquist, P.-Å.; Svensson, S.; Johansson, B.

    1984-06-01

    Gas phase core and valence electron spectra from UF6, excited by AlKα monochromatized x rays, in the binding energy range 0-1000 eV are presented. It is shown that the AlKα excited valence electron spectrum can be used to reassign the highest occupied molecular orbital (HOMO) in UF6. Many-body effects on the core levels are discussed and core level lifetimes are determined. The shift between solid phase and gas phase electron binding energies for core lines is used to discuss the U5 f population in UF6.

  6. Removal of contaminated concrete surfaces by microwave heating: Phase 1 results

    International Nuclear Information System (INIS)

    White, T.L.; Grubb, R.G.; Pugh, L.P.; Foster, D. Jr.; Box, W.D.

    1992-01-01

    Oak Ridge National Laboratory (ORNL) is developing a microwave heating process to remove radiologically contaminated surface layers from concrete. The microwave energy is directed at the concrete surface and heats the concrete and free water present in the concrete matrix. Continued heating produces steam-pressure-induced mechanical stresses that cause the concrete surface to burst. The concrete particles from this steam explosion are small enough to be removed by a vacuum system, yet less than 1% of the debris is small enough to pose an airborne contamination hazard. The first phase of this program has demonstrated reliable removal of noncontaminated concrete surfaces at frequencies of 2.45 GHz and 10.6 GHz. Continuous concrete removal rates of 1.07 cm 3 /s with 5.2 kW of 2.45.-GHz power and 2.11 cm 3 /s with 3.6 kW of 10.6-GHz power have been demonstrated. Figures-of-merit for microwave removal of concrete have been calculated to be 0.21 cm 3 /s/kW at 2.45 GHz and 0.59 cm 3 /s/kW at 10.6 GHz. The amount of concrete removed in a single pass can be controlled by choosing the frequency and power of the microwave system

  7. Characterizing the correlations between local phase fractions of gas-liquid two-phase flow with wire-mesh sensor.

    Science.gov (United States)

    Tan, C; Liu, W L; Dong, F

    2016-06-28

    Understanding of flow patterns and their transitions is significant to uncover the flow mechanics of two-phase flow. The local phase distribution and its fluctuations contain rich information regarding the flow structures. A wire-mesh sensor (WMS) was used to study the local phase fluctuations of horizontal gas-liquid two-phase flow, which was verified through comparing the reconstructed three-dimensional flow structure with photographs taken during the experiments. Each crossing point of the WMS is treated as a node, so the measurement on each node is the phase fraction in this local area. An undirected and unweighted flow pattern network was established based on connections that are formed by cross-correlating the time series of each node under different flow patterns. The structure of the flow pattern network reveals the relationship of the phase fluctuations at each node during flow pattern transition, which is then quantified by introducing the topological index of the complex network. The proposed analysis method using the WMS not only provides three-dimensional visualizations of the gas-liquid two-phase flow, but is also a thorough analysis for the structure of flow patterns and the characteristics of flow pattern transition. This article is part of the themed issue 'Supersensing through industrial process tomography'. © 2016 The Author(s).

  8. Contamination of medical gas and water pipelines in a new hospital building.

    Science.gov (United States)

    Eichhorn, J H; Bancroft, M L; Laasberg, L H; du Moulin, G C; Saubermann, A J

    1977-04-01

    Medical gases and water were sampled and tested for purity prior to the opening of a 176-bed addition to a 450-bed general hospital. Contamination was found. In delivered oxygen, compressed air, and nitrous oxide, this consisted of a volatile hydrocarbon at an initial concentration of 10 parts per million and a dust of fine gray particulate matter. In water from new taps bacterial contamination with as many 400,000 organisms per 100 ml was present. All these contaminants were considered potential hazards to patient safety. Studies were done to help delineate the nature and origin of these contaminants. Each contaminant was eventually largely eliminated by purging the respective pipeline systems with continuous flows. Planners, builders, and responsible medical personnel must be aware of the potential for such hazards in a new hospital building.

  9. Flow measurement in two-phase (gas-liquid) systems

    International Nuclear Information System (INIS)

    Hewitt, G.F.; Whalley, P.B.

    1980-01-01

    The main methods of measuring mass flow and quality in gas-liquid flows in industrial situations are reviewed. These include gamma densitometry coupled with differential pressure devices such as crifice plates, turbine flow meters and drag screens. For each method the principle of operation, and the advantages and disadvantages, are given. Some further techniques which are currently being investigated and developed for routine use are also described briefly. Finally the detailed flow measurements possible on a particular flow pattern - annular flow - is examined. (author)

  10. Ethylene epoxidation promoted by methane gas-phase thermic oxidation. The influence of equivalence ratio and gas flow velocity

    International Nuclear Information System (INIS)

    Grigoryan, R.R.; Arsentiev, S.D.; Mantashyan, A.A.

    2008-01-01

    Ethylene epoxidation promoted by methane gas-phase thermic oxidation has been studied. The studies were carried out in a two-sectional reactor under flow conditions. The most experiments were performed at temperatures T 1 - 983 K, T 2 - 778 K and pressure P = 86,7 kPa. It was shown that when methane is oxidized in the first section of the reactor and ethylene is put into the second section, epoxidation of olefin occurs through the alkyl peroxy radical interaction with double bond of olefin. It was established that the dependences of epoxidation rate on equivalence ratio and gas flow velocity pass through maximum. The substitution of methane by inert gas (argon) in the first section leads to significant decrease of rate of ethylene oxide accumulation in the second section

  11. Analysis of a gas-phase partitioning tracer test conducted in an unsaturated fractured-clay formation.

    Science.gov (United States)

    Simon, Michelle A; Brusseau, Mark L

    2007-03-20

    The gas-phase partitioning tracer method was used to estimate non-aqueous phase liquid (NAPL), water, and air saturations in the vadose zone at a chlorinated-solvent contaminated field site in Tucson, AZ. The tracer test was conducted in a fractured-clay system that is the confining layer for the underlying regional aquifer. Three suites of three tracers were injected into wells located 14, 24, and 24 m from a single, central extraction well. The tracers comprised noble gases (traditionally thought to be nonsorbing), alkanes (primarily water partitioning), perfluorides (primarily NAPL partitioning), and halons (both NAPL and water partitioning). Observations of vacuum response were consistent with flow in a fractured system. The halon tracers exhibited the greatest amount of retardation, and helium and the perfluoride tracers the least. The alkane tracers were unexpectedly more retarded than the perfluoride tracers, indicating low NAPL saturations and high water saturations. An NAPL saturation of 0.01, water saturation of 0.215, and gas saturation of 0.775 was estimated based on analysis of the suite of tracers comprising helium, perfluoromethylcyclohexane and dibromodifluoromethane, which was considered to be the most robust set. The estimated saturations compare reasonably well to independently determined values.

  12. Cold flame on Biofilm - Transport of Plasma Chemistry from Gas to Liquid Phase

    Science.gov (United States)

    Kong, Michael

    2014-10-01

    One of the most active and fastest growing fields in low-temperature plasma science today is biological effects of gas plasmas and their translation in many challenges of societal importance such as healthcare, environment, agriculture, and nanoscale fabrication and synthesis. Using medicine as an example, there are already three FDA-approved plasma-based surgical procedures for tissue ablation and blood coagulation and at least five phase-II clinical trials on plasma-assisted wound healing therapies. A key driver for realizing the immense application potential of near room-temperature ambient pressure gas plasmas, commonly known as cold atmospheric plasmas or CAP, is to build a sizeable interdisciplinary knowledge base with which to unravel, optimize, and indeed design how reactive plasma species interact with cells and their key components such as protein and DNA. Whilst a logical objective, it is a formidable challenge not least since existing knowledge of gas discharges is largely in the gas-phase and therefore not directly applicable to cell-containing matters that are covered by or embedded in liquid (e.g. biofluid). Here, we study plasma inactivation of biofilms, a jelly-like structure that bacteria use to protect themselves and a major source of antimicrobial resistance. As 60--90% of biofilm is made of water, we develop a holistic model incorporating physics and chemistry in the upstream CAP-generating region, a plasma-exit region as a buffer for as-phase transport, and a downstream liquid region bordering the gas buffer region. A special model is developed to account for rapid chemical reactions accompanied the transport of gas-phase plasma species through the gas-liquid interface and for liquid-phase chemical reactions. Numerical simulation is used to illustrate how key reactive oxygen species (ROS) are transported into the liquid, and this is supported with experimental data of both biofilm inactivation using plasmas and electron spin spectroscopy (ESR

  13. Gas-phase kinetics modifies the CCN activity of a biogenic SOA.

    Science.gov (United States)

    Vizenor, A E; Asa-Awuku, A A

    2018-02-28

    Our current knowledge of cloud condensation nuclei (CCN) activity and the hygroscopicity of secondary organic aerosol (SOA) depends on the particle size and composition, explicitly, the thermodynamic properties of the aerosol solute and subsequent interactions with water. Here, we examine the CCN activation of 3 SOA systems (2 biogenic single precursor and 1 mixed precursor SOA system) in relation to gas-phase decay. Specifically, the relationship between time, gas-phase precursor decay and CCN activity of 100 nm SOA is studied. The studied SOA systems exhibit a time-dependent growth of CCN activity at an instrument supersaturation of ∼0.2%. As such, we define a critical activation time, t 50 , above which a 100 nm SOA particle will activate. The critical activation time for isoprene, longifolene and a mixture of the two precursor SOA is 2.01 hours, 2.53 hours and 3.17 hours, respectively. The activation times are then predicted with gas-phase kinetic data inferred from measurements of precursor decay. The gas-phase prediction of t 50 agrees well with CCN measured t 50 (within 0.05 hours of the actual critical times) and suggests that the gas-to-particle phase partitioning may be more significant for SOA CCN prediction than previously thought.

  14. In Situ Environmental TEM in Imaging Gas and Liquid Phase Chemical Reactions for Materials Research.

    Science.gov (United States)

    Wu, Jianbo; Shan, Hao; Chen, Wenlong; Gu, Xin; Tao, Peng; Song, Chengyi; Shang, Wen; Deng, Tao

    2016-11-01

    Gas and liquid phase chemical reactions cover a broad range of research areas in materials science and engineering, including the synthesis of nanomaterials and application of nanomaterials, for example, in the areas of sensing, energy storage and conversion, catalysis, and bio-related applications. Environmental transmission electron microscopy (ETEM) provides a unique opportunity for monitoring gas and liquid phase reactions because it enables the observation of those reactions at the ultra-high spatial resolution, which is not achievable through other techniques. Here, the fundamental science and technology developments of gas and liquid phase TEM that facilitate the mechanistic study of the gas and liquid phase chemical reactions are discussed. Combined with other characterization tools integrated in TEM, unprecedented material behaviors and reaction mechanisms are observed through the use of the in situ gas and liquid phase TEM. These observations and also the recent applications in this emerging area are described. The current challenges in the imaging process are also discussed, including the imaging speed, imaging resolution, and data management. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. The behaviour of dense, non-aqueous phase liquid contaminants in heterogeneous porous media

    Energy Technology Data Exchange (ETDEWEB)

    Kueper, B.H.

    1989-01-01

    Dense, non-aqueous phase liquids (DNAPLs) such as polychlorinated biphenyl oils, creosotes and chlorinated solvents represent a unique class of groundwater contaminants, with many being denser and less viscous than water, and only slightly soluble in water. The behavior of DNAPLs in naturally occurring sandy aquifers was examined with an emphasis on the influence of porous media heterogeneity. Extensive use is made of laboratory mesurements and numerical modelling to illustrate that the behavior of DNAPLs in heterogeneous porous media is governed by the spatial distribution of capillary properties. The degree of lateral spreading of DNAPLs on lenses of different permeability is found to be a function of fluid density, as well as interfacial tension between the fluids of concern and the source strength of DNAPL released. A two dimensional vertical section two phase flow model was developed using the finite difference technique. The numerical model was validated against a parallel plate laboratory experiment involving the infiltration of tetrachloroethylene into a heterogeneous sand pack, yielding excellent agreement between the experimental and numerical simulation results. Numerical simulations were performed in a statistically generated realization of the Borden aquifer to investigate the sensitivity of fluid properties and source strength on the migration of DNAPL in a field scale aquifer. Distribution of DNAPL was found to be extremely chaotic. 6 refs., 65 figs., 13 tabs.

  16. Modelling gas migration in compacted bentonite: gambit club phase 3. Final report

    International Nuclear Information System (INIS)

    Hoch, A.R.; Cliffe, K.A.; Swift, B.T.; Rodwell, W.R.

    2004-04-01

    This report describes the third phase of a programme of work to develop a computational model of gas migration through highly compacted water-saturated bentonite. One difficulty with this endeavour is the definitive determination of the mechanism of the gas migration from the available experimental data. The report contains a brief review of the experimental data and their interpretation. The model development work reported involves the investigation of two ways of enhancing a model proposed in the previous phase of the programme. This model was based on the concept that gas migration pathways were created by consolidating the clay fabric by application of gas pressure to create porosity through which the gas could flow. The two developments of this model that are separately explored in this work are: (a) The incorporation of a proper treatment of the stress-strain behaviour of the clay in (b) response to gas migration. The previous model had only considered stress effects through simple volume changes to the clay fabric. The inclusion of a dual-porosity feature into the model in an attempt to address the role that the clay fabric might play in gas migration through the clay, in particular the role that pre-existing interstack voids might have in gas migration. The consideration of hysteresis effects was also included in this study. As in previous GAMBIT Club work, the models are tested against the results of laboratory experiments. (orig.)

  17. Contributions of gas-phase plasma chemistry to surface modifications and gas-surface interactions: investigations of fluorocarbon rf plasmas

    Science.gov (United States)

    Cuddy, Michael F., II

    The fundamental aspects of inductively coupled fluorocarbon (FC) plasma chemistry were examined, with special emphasis on the contributions of gas-phase species to surface modifications. Characterization of the gas-phase constituents of single-source CF4-, C2F6-, C3F 8-, and C3F6-based plasmas was performed using spectroscopic and mass spectrometric techniques. The effects of varying plasma parameters, including applied rf power (P) and system pressure (p) were examined. Optical emission spectroscopy (OES) and laser-induced fluorescence (LIF) spectroscopy were employed to monitor the behavior of excited and ground CFx (x = 1,2) radicals, respectively. Mass spectrometric techniques, including ion energy analyses, elucidated behaviors of nascent ions in the FC plasmas. These gas-phase data were correlated with the net effect of substrate processing for Si and ZrO2 surfaces. Surface-specific analyses were performed for post-processed substrates via x-ray photoelectron spectroscopy (XPS) and contact angle goniometry. Generally, precursors with lower F/C ratios tended to deposit robust FC films of high surface energy. Precursors of higher F/C ratio, such as CF4, were associated with etching or removal of material from surfaces. Nonetheless, a net balance between deposition of FC moieties and etching of material exists for each plasma system. The imaging of radicals interacting with surfaces (IRIS) technique provided insight into the phenomena occurring at the interface of the plasma gas-phase and substrate of interest. IRIS results demonstrate that CFx radicals scatter copiously, with surface scatter coefficients, S, generally greater than unity under most experimental conditions. Such considerable S values imply surface-mediated production of the CFx radicals at FC-passivated sites. It is inferred that the primary route to surface production of CFx arises from energetic ion bombardment and ablation of surface FC films. Other factors which may influence the observed CFx

  18. Experimental and numerical investigation of gas phase freeboard combustion

    DEFF Research Database (Denmark)

    Andersen, Jimmy; Jensen, Peter Arendt; Hvid, S.L.

    2009-01-01

    In part 1 of the present work (10.1021/ef900752a), experimental data and computational fluid dynamics (CFD) modeling predictions for velocity field, temperatures, and major species were compared fora 50 kW axisymmetric, non-swirling natural gas Fired combustion setup, constructed to simulate...... approach with the De Soete global scheme and the combination of a skeletal combustion mechanism with the analytically reduced N scheme provided it reasonable agreement with the experimental data. Most of the tested ammonia oxidation schemes were able to qualitatively predict the trends in NO formation...... going from one operational case to the other, but the main combustion solution on which the ammonia oxidation was based proved to have a large impact on the quantitative NO prediction....

  19. Gas-phase chemistry of element 114, flerovium

    Directory of Open Access Journals (Sweden)

    Yakushev Alexander

    2016-01-01

    Full Text Available Element 114 was discovered in 2000 by the Dubna-Livermore collaboration, and in 2012 it was named flerovium. It belongs to the group 14 of the periodic table of elements. A strong relativistic stabilisation of the valence shell 7s27p21/2 is expected due to the orbital splitting and the contraction not only of the 7s2 but also of the spherical 7p21/2 closed subshell, resulting in the enhanced volatility and inertness. Flerovium was studied chemically by gas-solid chromatography upon its adsorption on a gold surface. Two experimental results on Fl chemistry have been published so far. Based on observation of three atoms, a weak interaction of flerovium with gold was suggested in the first study. Authors of the second study concluded on the metallic character after the observation of two Fl atoms deposited on gold at room temperature.

  20. Improving gas separation properties of polymeric membranes based on glassy polymers by gas phase fluorination

    NARCIS (Netherlands)

    Syrtsova, D.A.; Syrtsova, D.A.; Kharitonov, A.P.; Teplyakov, V.V.; Koops, G.H.

    2002-01-01

    The application area of existing gas separation membranes is limited by commercially available polymers for their preparation. In many cases the separation selectivity of these polymers is not sufficient for effective separation processes. One of the ways to improve the separation effectivity of

  1. Chemical Alterations of Pb using Flue Gas Desulfurization Gypsum (FGDG) in two contaminated soils

    Data.gov (United States)

    U.S. Environmental Protection Agency — The data include chemical composition of Pb contaminated soils by adding FGDG as an amendment. The data shows the changes in Pb speciation to sulfur based minerals....

  2. Radiological Emergency Preparedness after the Early Phase of an Accident : Focusing on an Air Contamination Event

    International Nuclear Information System (INIS)

    Jeong, Hyo Joon; Hwang, Won Tae; Kim, Eun Han; Han, Moon Hee

    2010-01-01

    Toxic materials in an urban area can be caused by a variety of events, such as accidental releases on industrial complexes, accidents during the transportation of hazardous materials and intentional explosions. Most governments around the world and their citizens have become increasingly worried about intentional accidents in urban area after the 911 terrorist attack in the United States of America. Even though there have been only a few attempted uses of Radiological Dispersal Devices (RDDs), accidental releases have occurred many times at commercial nuclear power plants and nuclear waste disposal sites. When an intentional release of radioactive materials occurs in an urban area, air quality for radioactive materials in the environment is of great importance to take action for countermeasures and environmental risk assessments. Atmospheric modeling is part of the decision making tasks and that it is particularly important for emergency managers as they often need to take actions quickly on very inadequate information(1). A simple model such as HOTSPOT required wind direction and source term would be enough to support the decision making in the early phase of an accident, but more sophisticated atmospheric modeling is required to adjust decontamination area and relocation etc after the early phase of an accidental event. In this study, we assume an explosion of 137 Cs using RDDs in the metropolitan area of Soul, South Korea. California Puff Model (CALPUFF) is used to calculate an atmospheric dispersion and transport for 137 Cs. Atmospheric dispersion and quantitative radiological risk analysis for 137 Cs were performed assuming an intentional explosion in the metropolitan area of Soul, South Korea after the early phase of emergency. These kinds of atmospheric modeling and risk analysis could provide a means for decision makers to take action on important issues such as the cleanup of the contaminated area and countermeasures to protect the public caused by

  3. Formation of 9,10-phenanthrenequinone by atmospheric gas-phase reactions of phenanthrene

    Science.gov (United States)

    Wang, Lin; Atkinson, Roger; Arey, Janet

    Phenanthrene is a 3-ring polycyclic aromatic hydrocarbon which exists mainly in the gas-phase in the atmosphere. Recent concern over the presence of 9,10-phenanthrenequinone in ambient particles led us to study the products of the gas-phase reactions of phenanthrene with hydroxyl radicals, nitrate radicals and ozone. The formation yields of 9,10-phenanthrenequinone were measured to be ˜3%, 33±9%, and ˜2% from the OH radical, NO 3 radical and O 3 reactions, respectively. Calculations suggest that daytime OH radical-initiated and nighttime NO 3 radical-initiated reactions of gas-phase phenanthrene may be significant sources of 9,10-phenanthrenequinone in ambient atmospheres. In contrast, the ozone reaction with phenanthrene is unlikely to contribute significantly to ambient 9,10-phenanthrenequinone.

  4. Measurement of pressure fluctuation in gas-liquid two-phase vortex street

    International Nuclear Information System (INIS)

    Sun Zhiqiang; Sang Wenhui; Zhang Hongjian

    2009-01-01

    The pressure fluctuation in the wake is an important parameter to characterize the shedding process of gas-liquid two-phase Karman vortex street. This paper investigated such pressure fluctuations in a horizontal pipe using air and water as the tested fluid media. The dynamic signal representing the pressure fluctuation was acquired by the duct-wall differential pressure method. Results show that in the wake of the gas-liquid two-phase Karman vortex street, the frequency of the pressure fluctuation is linear with the Reynolds number when the volume void fraction is within the range of 18%. Moreover, the mean amplitude of the pressure fluctuation decreases with the volume void fraction, and the mean amplitude is larger at higher water flowrates under the same volume void fraction. These findings contribute to an in-depth understanding of the gas-liquid two-phase Karman vortex street.

  5. Photoresponse of the protonated Schiff-base retinal chromophore in the gas phase

    DEFF Research Database (Denmark)

    Toker, Jonathan; Rahbek, Dennis Bo; Kiefer, H V

    2013-01-01

    The fragmentation, initiated by photoexcitation as well as collisionally-induced excitation, of several retinal chromophores was studied in the gas phase. The chromophore in the protonated Schiff-base form (RPSB), essential for mammalian vision, shows a remarkably selective photoresponse. The sel......The fragmentation, initiated by photoexcitation as well as collisionally-induced excitation, of several retinal chromophores was studied in the gas phase. The chromophore in the protonated Schiff-base form (RPSB), essential for mammalian vision, shows a remarkably selective photoresponse...... modifications of the chromophore. We propose that isomerizations play an important role in the photoresponse of gas-phase retinal chromophores and guide internal conversion through conical intersections. The role of protein interactions is then to control the specificity of the photoisomerization in the primary...

  6. Metal-Organic Framework Thin Films as Stationary Phases in Microfabricated Gas-Chromatography Columns.

    Energy Technology Data Exchange (ETDEWEB)

    Read, Douglas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sillerud, Colin Halliday [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    The overarching goal of this project is to integrate Sandia's microfabricated gas-chromatography ( GC) columns with a stationary phase material that is capable of retaining high-volatility chemicals and permanent gases. The successful integration of such a material with GCs would dramatically expand the repertoire of detectable compounds for Sandia's various microanalysis systems. One such promising class of candidate materials is metal-organic frameworks (MOFs). In this report we detail our methods for controlled deposition of HKUST-1 MOF stationary phases within GC columns. We demonstrate: the chromatographic separation of natural gas; a method for determining MOF film thickness from chromatography alone; and the first-reported GC x GC separation of natural gas -- in general -- let alone for two disparate MOF stationary phases. In addition we determine the fundamental thermodynamic constant for mass sorption, the partition coefficient, for HKUST-1 and several light hydrocarbons and select toxic industrial chemicals.

  7. The Stability of CI02 as a Product of Gas Phase Decontamination Treatments

    International Nuclear Information System (INIS)

    Simmons, D. W.

    1994-01-01

    The gas phase decontamination project is investigating the use of chlorine trifluoride (ClF 3 ) to fluorinate nonvolatile uranium deposits to produce uranium hexafluoride (UF 6 ) gas. The potential existence of chlorine dioxide (ClO 2 ) during gas phase decontamination with ClF 3 has been the subject of recent safety discussions. Some of the laboratory data collected during feasibility studies of the gas phase process has been evaluated for the presence of ClO 2 in the product gas stream. The preliminary evidence to date can be summarized as follows: (1) ClO 2 was not detected in the flow loop in the absence of ClF 3 ; (2) ClO 2 was not detected in the static reactors in the absence of both ClF 3 and ClF; and (3) ClO 2 was detected in a static reactor in the absence of all fluorinating gases. The experimental evidence suggests that ClO 2 will not exist in the presence of ClF 3 , ClF, or UF 6 . The data analyzed to date is insufficient to determine the stability of ClO 2 in the presence of ClO 2 F. Thermodynamic calculations of the ClF 3 + H 2 O system support the experimental evidence, and suggest that ClO 2 will not exist in the presence of ClO 2 F. Additional experimental efforts are needed to provide a better understanding of the gas phase ClF 3 treatments and the product gases. However, preliminary evidence to date suggests that ClO 2 should not be present as a product during the normal operations of the gas phase decontamination project

  8. A gas-phase reactor powered by solar energy and ethanol for H2 production

    International Nuclear Information System (INIS)

    Ampelli, Claudio; Genovese, Chiara; Passalacqua, Rosalba; Perathoner, Siglinda; Centi, Gabriele

    2014-01-01

    In the view of H 2 as the future energy vector, we presented here the development of a homemade photo-reactor working in gas phase and easily interfacing with fuel cell devices, for H 2 production by ethanol dehydrogenation. The process generates acetaldehyde as the main co-product, which is more economically advantageous with respect to the low valuable CO 2 produced in the alternative pathway of ethanol photoreforming. The materials adopted as photocatalysts are based on TiO 2 substrates but properly modified with noble (Au) and not-noble (Cu) metals to enhance light harvesting in the visible region. The samples were characterized by BET surface area analysis, Transmission Electron Microscopy (TEM) and UV–visible Diffusive Reflectance Spectroscopy, and finally tested in our homemade photo-reactor by simulated solar irradiation. We discussed about the benefits of operating in gas phase with respect to a conventional slurry photo-reactor (minimization of scattering phenomena, no metal leaching, easy product recovery, etc.). Results showed that high H 2 productivity can be obtained in gas phase conditions, also irradiating titania photocatalysts doped with not-noble metals. - Highlights: • A gas-phase photoreactor for H 2 production by ethanol dehydrogenation was developed. • The photocatalytic behaviours of Au and Cu metal-doped TiO 2 thin layers are compared. • Benefits of operating in gas phase with respect to a slurry reactor are presented. • Gas phase conditions and use of not-noble metals are the best economic solution

  9. Steam stripping of the unsaturated zone of contaminated sub-soils: the effect of diffusion/dispersion in the start-up phase

    NARCIS (Netherlands)

    Brouwers, Jos; Gilding, B.H.

    2006-01-01

    The unsteady process of steam stripping of the unsaturated zone of soils contaminated with volatile organic compounds (VOCs) is addressed. A model is presented. It accounts for the effects of water and contaminants remaining in vapour phase, as well as diffusion and dispersion of contaminants in

  10. Distribution of Organophosphate Esters between the Gas and Particle Phase-Model Predictions vs Measured Data.

    Science.gov (United States)

    Sühring, Roxana; Wolschke, Hendrik; Diamond, Miriam L; Jantunen, Liisa M; Scheringer, Martin

    2016-07-05

    Gas-particle partitioning is one of the key factors that affect the environmental fate of semivolatile organic chemicals. Many organophosphate esters (OPEs) have been reported to primarily partition to particles in the atmosphere. However, because of the wide range of their physicochemical properties, it is unlikely that OPEs are mainly in the particle phase "as a class". We compared gas-particle partitioning predictions for 32 OPEs made by the commonly used OECD POV and LRTP Screening Tool ("the Tool") with the partitioning models of Junge-Pankow (J-P) and Harner-Bidleman (H-B), as well as recently measured data on OPE gas-particle partitioning. The results indicate that half of the tested OPEs partition into the gas phase. Partitioning into the gas phase seems to be determined by an octanol-air partition coefficient (log KOA) -5 (PL in Pa), as well as the total suspended particle concentration (TSP) in the sampling area. The uncertainty of the physicochemical property data of the OPEs did not change this estimate. Furthermore, the predictions by the Tool, J-P- and H-B-models agreed with recently measured OPE gas-particle partitioning.

  11. Synthesis gas demonstration plant program, Phase I. Site confirmation report

    Energy Technology Data Exchange (ETDEWEB)

    1978-12-01

    With few reservations, the Baskett, Kentucky site exhibits the necessary characteristics to suggest compatibility with the proposed Synthesis Gas Demonstration Plant Project. An evaluation of a broad range of technical disciplinary criteria in consideration of presently available information indicated generally favorable conditions or, at least, conditions which could be feasibly accommodated in project design. The proximity of the Baskett site to market areas and sources of raw materials as well as a variety of transportation facilities suggests an overall favorable impact on Project economic feasibility. Two aspects of environmental engineering, however, have been identified as areas where the completion or continuation of current studies are required before removing all conditions on site suitability. The first aspect involves the current contradictory status of existing land use and planning ordinances in the site area. Additional investigation of the legality of, and local attitudes toward, these present plans is warranted. Secondly, terrestrial and aquatic surveys of plant and animal life species in the site area must be completed on a seasonal basis to confirm the preliminary conclusion that no exclusionary conditions exist.

  12. Multiscale and luminescent, hollow microspheres for gas phase thermometry.

    Science.gov (United States)

    Bischoff, Lothar; Stephan, Michael; Birkel, Christina S; Litterscheid, Christian F; Dreizler, Andreas; Albert, Barbara

    2018-01-12

    Recently developed laser-based measurement techniques are used to image the temperatures and velocities in gas flows. They require new phosphor materials with an unprecedented combination of properties. A novel synthesis procedure is described here; it results in hierarchically structured, hollow microspheres of Eu 3+ -doped Y 2 O 3 , with unusual particle sizes and very good characteristics compared to full particles. Solution-based precipitation on polymer microballoons produces very stable and luminescent, ceramic materials of extremely low density. As a result of the - compared to established template-directed syntheses - reduced mass of polymer that is lost upon calcination, micron-sized particles are obtained with mesoporous walls, low defect concentrations, and nanoscale wall thicknesses. They can be produced with larger diameters (~25 µm) compared to known hollow spheres and exhibit an optimized flow behavior. Their temperature sensing properties and excellent fluidic follow-up behavior are shown by determining emission intensity ratios in a specially designed heating chamber. Emission spectroscopy and imaging, electron microscopy and X-ray diffraction results are presented for aerosolizable Y 2 O 3 with an optimized dopant concentration (8%). Challenges in the field of thermofluids can be addressed by combined application of thermometry and particle image velocimetry with such hollow microparticles.

  13. Use of dilute ammonia gas for treatment of 1,2,3-trichloropropane and explosives-contaminated soils.

    Science.gov (United States)

    Coyle, Charles G; Waisner, Scott A; Medina, Victor F; Griggs, Chris S

    2017-12-15

    Laboratory studies were performed to test a novel reactive gas process for in-situ treatment of soils containing halogenated propanes or explosives. A soil column study, using a 5% ammonia-in-air mixture, established that the treatment process can increase soil pH from 7.5 to 10.2. Batch reactor experiments were performed to demonstrate contaminant destruction in sealed jars exposed to ammonia. Comparison of results from batch reactors that were, and were not, exposed to ammonia demonstrated reductions in concentrations of 1,2,3-trichloropropane (TCP), 1,3-dichloropropane (1,3-DCP), 1,2-dicholoropropane (1,2-DCP) and dibromochloropropane (DBCP) that ranged from 34 to 94%. Decreases in TCP concentrations at 23° C ranged from 37 to 65%, versus 89-94% at 62° C. A spiked soil column study was also performed using the same set of contaminants. The study showed a pH penetration distance of 30 cm in a 2.5 cm diameter soil column (with a pH increase from 8 to > 10), due to treatment via 5% ammonia gas at 1 standard cubic centimeter per minute (sccm) for 7 days. Batch reactor tests using explosives contaminated soils exhibited a 97% decrease in 2,4,6-trinitrotoluene (TNT), an 83% decrease in nitrobenzene, and a 6% decrease in hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). A biotransformation study was also performed to investigate whether growth of ammonia-oxidizing microorganisms could be stimulated via prolonged exposure of soil to ammonia. Over the course of the 283 day study, only a very small amount of nitrite generation was observed; indicating very limited ammonia monooxygenase activity. Overall, the data indicate that ammonia gas addition can be a viable approach for treating halogenated propanes and some types of explosives in soils. Published by Elsevier Ltd.

  14. Three-dimensional, gas phase fuel cell with a laccase biocathode

    Science.gov (United States)

    Borole, Abhijeet P.; LaBarge, Samuel; Spott, Benjamin A.

    A fuel cell using an enzymatic biocathode operating in a gas phase mode is reported. The electrode was prepared using a three-dimensional conductive electrode matrix. An enzyme solution containing laccase and a mediator was distributed into a hydrophilic matrix of carbon felt fibers creating a porous gas-flowing electrode. A Pt-based gas diffusion electrode served as the anode. A maximum power density of 9.4 W m -2 (2.9 kW m -3) was obtained with 15 U of enzyme cm -2, with hydrogen as the fuel. Power density was found to be a function of the enzyme loading, air flow rate, volume of the liquid phase and the humidity of the air stream. The ability to use methanol and ethanol as vapors in gas phase was also shown. The introduction of three-dimensionality into the electrode architecture and operation of the fuel cell in a gas phase mode to supply the fuel and the oxidant demonstrates an avenue for improving the power density of EFCs.

  15. Impact of Contaminants Present in Coal-Biomass Derived Synthesis Gas on Water-gas Shift and Fischer-Tropsch Synthesis Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Alptekin, Gokhan [TDA Research, Inc., Wheat Ridge, CO (United States)

    2013-02-15

    Co-gasification of biomass and coal in large-scale, Integrated Gasification Combined Cycle (IGCC) plants increases the efficiency and reduces the environmental impact of making synthesis gas ("syngas") that can be used in Coal-Biomass-to-Liquids (CBTL) processes for producing transportation fuels. However, the water-gas shift (WGS) and Fischer-Tropsch synthesis (FTS) catalysts used in these processes may be poisoned by multiple contaminants found in coal-biomass derived syngas; sulfur species, trace toxic metals, halides, nitrogen species, the vapors of alkali metals and their salts (e.g., KCl and NaCl), ammonia, and phosphorous. Thus, it is essential to develop a fundamental understanding of poisoning/inhibition mechanisms before investing in the development of any costly mitigation technologies. We therefore investigated the impact of potential contaminants (H2S, NH3, HCN, AsH3, PH3, HCl, NaCl, KCl, AS3, NH4NO3, NH4OH, KNO3, HBr, HF, and HNO3) on the performance and lifetime of commercially available and generic (prepared in-house) WGS and FT catalysts.

  16. Searching for anthropogenic contaminants in human breast adipose tissues using gas chromatography-time-of-flight mass spectrometry.

    Science.gov (United States)

    Hernández, Félix; Portolés, Tania; Pitarch, Elena; López, Francisco J

    2009-01-01

    The potential of gas chromatography-time-of-flight mass spectrometry (GC-TOF MS) for screening anthropogenic organic contaminants in human breast adipose tissues has been investigated. Initially a target screening was performed for a list of 125 compounds which included persistent halogen pollutants [organochlorine (OC) pesticides, polychlorinated biphenylss (PCBs), polybrominated diphenyl ethers (PBDEs)], polyaromatic hydrocarbons (PAHs), alkylphenols, and a notable number of pesticides from the different fungicide, herbicide and insecticide families. Searching for target pollutants was done by evaluating the presence of up to five representative ions for every analyte, all measured at accurate mass (20-mDa mass window). The experimental ion abundance ratios were then compared to those of reference standards for confirmation. Sample treatment consisted of an extraction with hexane and subsequent normal-phase (NP) High performance liquid chromatography (HPLC) or SPE cleanup. The fat-free LC fractions were then investigated by GC-TOF MS.Full-spectral acquisition and accurate mass data generated by GC-TOF MS also allowed the investigation of nontarget compounds using appropriate processing software to manage MS data. Identification was initially based on library fit using commercial nominal mass libraries. This was followed by comparing the experimental accurate masses of the most relevant ions with the theoretical exact masses with calculations made using the elemental composition calculator included in the software.The application of both target and nontarget approaches to around 40 real samples allowed the detection and confirmation of several target pollutants including p,p'-DDE, hexachlorobenzene (HCB), and some polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Several nontarget compounds that could be considered anthropogenic pollutants were also detected. These included 3,5-di-tert-butyl-4-hydroxy-toluene (BHT) and its metabolite 3,5-di

  17. Probing the nuclear liquid-gas phase transition

    International Nuclear Information System (INIS)

    Pochodzalla, J.; Moehlenkamp, T.; Rubehn, T.; Schuettauf, A.; Zude, E.; Begemann-Blaich, M.; Blaich, T.; Emling, H.; Ferrero, A.; Kunze, W.D.; Lindenstruth, V.; Lynen, U.; Moroni, W.; Ocker, B.; Schwarz, C.; Seidel, W.; Serfling, V.; Trzcinski, A.; Tucholski, A.; Verde, G.

    1995-02-01

    Fragment distributions resulting from Au+Au collisions at an incident energy of E/A=600 MeV are studied. From the measured fragment and neutron distributions the mass and the excitation energy of the decaying pre-fragments were determined. A temperature scale was derived from observed yield ratios of He and Li isotopes. The relation between this isotope temperature and the excitation energy of the system exhibits a behavior which is expected for a phase transition. The nuclear vapor regime takes over at an excitation energy of 10 MeV per nucleon, a temperature of 5 MeV and may be characterized by a density of 0.15-0.3 normal nuclear density. (orig.)

  18. Gas phase THz spectroscopy of toxic agent simulant compounds using the AILES synchrotron beamline

    Science.gov (United States)

    Cuisset, A.; Smirnova, I.; Bocquet, R.; Hindle, F.; Mouret, G.; Yang, C.; Pirali, O.; Roy, P.

    2010-02-01

    A new study is currently underway aiming at recording and assigning the gas phase rovibrational spectra of several organophosphorus and organosulphur compounds in the THz frequency domain. Thanks to the exceptional properties of flux, brilliance and spectral range of the AILES beamline coupled to the FTIR spectrometer, the gas phase vibrational spectra of low volatility organophosphorous compounds have been recorded across the entire THz frequency range. High resolution FTIR spectroscopy was used to record the pure rotational and the low-frequency rovibrational spectrum of DMSO. A comparison between the spectra measured with the AILES beamline and the spectra obtained with optoelectronic THz sources is possible.

  19. Direct gas-phase epoxidation of propylene to propylene oxide through radical reactions: A theoretical study

    Science.gov (United States)

    Kizilkaya, Ali Can; Fellah, Mehmet Ferdi; Onal, Isik

    2010-03-01

    The gas-phase radical chain reactions which utilize O 2 as the oxidant to produce propylene oxide (PO) are investigated through theoretical calculations. The transition states and energy profiles were obtained for each path. The rate constants were also calculated. The energetics for the competing pathways indicate that PO can be formed selectively due to its relatively low activation barrier (9.3 kcal/mol) which is in a good agreement with the experimental value (11 kcal/mol) of gas-phase propylene epoxidation. The formation of the acrolein and combustion products have relatively high activation barriers and are not favored. These results also support the recent experimental findings.

  20. Acrolein Production by Gas-Phase Glycerol Dehydration Using PO₄/Nb₂O5 Catalysts.

    Science.gov (United States)

    Lee, Kyu Am; Ryoo, HeeKyoung; Ma, Byung Chol; Kim, Youngchul

    2018-02-01

    In this study, modified niobium oxide were prepared to study the addictive effects on the catalytic performance for gas-phase glycerol dehydration. The catalysts were characterized by N2 adsorption/desorption, XRD, NH3-TPD, FT-IR. The amount of phosphoric acid was up to 50 wt% in niobium. As a result, the highest glycerol conversion was achieved over 20 wt% PO4/Nb2O5. It indicates that the optimal amount of phosphoric acid leads the catalyst to have appropriate acidity which is an important factor for gas-phase glycerol dehydration.

  1. Product analysis of the gas-phase reaction of β-caryophyllene with ozone

    Science.gov (United States)

    Calogirou, A.; Kotzias, D.; Kettrup, A.

    The semivolatile ketoaldehydes 3,3-dimethyl-y-methylene-2-(3-oxobutyl)-cyclobutanebutanal 1 and 3,3-dimethyl-γ-oxo-2-(3-oxobutyl)-cyclobutanebutanal 2 and formaldehyde have been identified as the main products of the reaction of ß-caryophyllene with ozone in the gas phase. In minor amounts 9-methylene-,t,12,12-trimethyl-5-oxabicyclo[8.2.0.0.s]dodecane 3 was also formed. Nature and yields of these carbonyl products are discussed in terms of oxidation mechanisms involving the gas-phase reaction with ozone and OH radicals.

  2. Studies of gas phase ion/molecule reactions by Fourier transform ion cyclotron resonance mass spectrometry

    International Nuclear Information System (INIS)

    Kleingeld, J.C.

    1984-01-01

    An important field in which Fourier-transform ion cyclotron resonance has useful applications is that of gas phase ion chemistry, the subject of this thesis. First, the general picture of ion-molecule reactions in the gas phase is discussed. Next, some positive ion-molecule reactions are described, whereas the remaining chapters deal with negative ion-molecule reactions. Most of these studies have been performed using the FT-ICR method. Reactions involving H 3 O - and NH 4 - ions are described whereas the other chapters deal with larger organic complexes. (Auth.)

  3. Parents of two-phase flow and theory of “gas-lift”

    Directory of Open Access Journals (Sweden)

    Zitek Pavel

    2014-03-01

    Full Text Available This paper gives a brief overview of types of two-phase flow. Subsequently, it deals with their mutual division and problems with accuracy boundaries among particular types. It also shows the case of water flow through a pipe with external heating and the gradual origination of all kinds of flow. We have met it in solution of safety condition of various stages in pressurized and boiling water reactors. In the MSR there is a problem in the solution of gas-lift using helium as a gas and its secondary usage for clearing of the fuel mixture from gaseous fission products. Theory of gas-lift is described.

  4. Continuous fixed-bed gas-phase hydroformylation using supported ionic liquid-phase (SILP) Rh catalysts

    DEFF Research Database (Denmark)

    Riisager, Anders; Wasserscheid, Peter; Van Hal, R.

    2003-01-01

    Continuous flow gas-phase hydroformylation of propene was performed using novel supported ionic liquid-phase (SILP) catalysts containing immobilized Rh complexes of the biphosphine ligand sulfoxantphos in the ionic liquids 1-n-butyl-3-methylimidazolium hexafluorophosphate and halogen-free 1-n......-butyl-3-methylimidazolium n-octylsulfate on silica support. The Rh-sulfoxantphos SILP catalysts proved to be more regioselective than catalysts without ligand and the analogous ionic liquid-free catalysts, giving up to 96% linear product. Furthermore, the performance of the catalysts was generally...

  5. Molecular simulation of excess isotherm and excess enthalpy change in gas-phase adsorption.

    Science.gov (United States)

    Do, D D; Do, H D; Nicholson, D

    2009-01-29

    We present a new approach to calculating excess isotherm and differential enthalpy of adsorption on surfaces or in confined spaces by the Monte Carlo molecular simulation method. The approach is very general and, most importantly, is unambiguous in its application to any configuration of solid structure (crystalline, graphite layer or disordered porous glass), to any type of fluid (simple or complex molecule), and to any operating conditions (subcritical or supercritical). The behavior of the adsorbed phase is studied using the partial molar energy of the simulation box. However, to characterize adsorption for comparison with experimental data, the isotherm is best described by the excess amount, and the enthalpy of adsorption is defined as the change in the total enthalpy of the simulation box with the change in the excess amount, keeping the total number (gas + adsorbed phases) constant. The excess quantities (capacity and energy) require a choice of a reference gaseous phase, which is defined as the adsorptive gas phase occupying the accessible volume and having a density equal to the bulk gas density. The accessible volume is defined as the mean volume space accessible to the center of mass of the adsorbate under consideration. With this choice, the excess isotherm passes through a maximum but always remains positive. This is in stark contrast to the literature where helium void volume is used (which is always greater than the accessible volume) and the resulting excess can be negative. Our definition of enthalpy change is equivalent to the difference between the partial molar enthalpy of the gas phase and the partial molar enthalpy of the adsorbed phase. There is no need to assume ideal gas or negligible molar volume of the adsorbed phase as is traditionally done in the literature. We illustrate this new approach with adsorption of argon, nitrogen, and carbon dioxide under subcritical and supercritical conditions.

  6. Studies of cluster-assembled materials: From gas phase to condensed phase

    Science.gov (United States)

    Gao, Lin

    . After being mass gated in a reflectron equipped time-of-flight mass spectrometer (TOF-MS) and deposited onto TEM grids, the resultant specimens can be loaded onto high-resolution TEM investigation via electron diffraction. In conclusion, soft-landing of mass selected clusters has been shown to be a successful approach to obtain structural information on Zr-Met-Car cluster-assembled materials collected from the gas phase. TEM images indicate the richness of the morphologies associated with these cluster crystals. However, passivation methods are expected to be examined further to overcome the limited stabilities of these novel clusters. From this initial study, it's shown the promising opportunity to study other Met-Cars species and more cluster-based materials. Experimental results of reactions run with a solvothermal synthesis method obtained while searching for new Zr-C cluster assembled materials, are reported. One unexpected product in single crystal form was isolated and tentatively identified by X-ray diffraction to be [Zr6i O(OH)O12·2(Bu)4], with space group P2 1/n and lattice parameters of a = 12.44 A, b = 22.06 A, c = 18.40 A, alpha = 90°, beta = 105°, gamma = 90°, V = 4875 A3 and R 1 = 3.15% for the total observed data (I ≥ 2 sigma I) and oR2 = 2.82%. This novel hexanuclear Zr(IV)-oxo-hydroxide cluster anion may be the first member in polyoxometalates class with metal atoms from the IVB group and having Oh symmetry. Alternatively, it may be the first member in {[(Zr6Z)X 12]X6}m- class with halides replaced by oxo- and hydroxyl groups and with an increased oxidation state of Zr. It is predicted to bear application potentials directed by both families. This work could suggest a direction in which the preparation of Zr-C cluster-assembled materials in a liquid environment may be eventually fulfilled. 1,3-Bis(diethylphosphino)propane (depp) protected small gold clusters are studied via multiple techniques, including Electrospray Ionization Mass Spectrometry

  7. Diurnal variability of gas phase and surface water ethanol in southeastern North Carolina, USA

    Science.gov (United States)

    Kieber, R. J.; Powell, J. P.; Foley, L.; Mead, R. N.; Willey, J. D.; Avery, G. B.

    2017-11-01

    Diurnal variations in gas phase and surface water concentrations of ethanol and acetaldehyde were investigated at five locations in southeastern North Carolina, USA. There were distinct diurnal oscillations observed in gas phase concentrations with maxima occurring in late afternoon suggesting that photochemical production is an important process in the cycling of these analytes in the troposphere. The rapid decrease in concentrations after the mid day maximum suggests that there is also an atmospheric photochemical sink for both analytes most likely involving photo produced hydroxyl radicals with a half-life on the order of hours rather than days at ground level. Ethanol concentrations in the surface microlayer taken at the same time as gas phase samples had a very similar diurnal profile suggesting photochemical processes, in addition to atmospheric deposition, play a role in the aqueous phase cycling of both analytes. The concentration of ethanol and acetaldehyde increased significantly in flasks containing freshwater collected from the Cape Fear River exposed to simulated sunlight for 6 h underscoring the importance of in situ photochemical production. Results of this study are significant because they represent the first simultaneous analyses of the temporal variability of ethanol and acetaldehyde concentrations in the gas and aqueous phases. These measurements are essential in order to better define the processes involved in the global biogeochemical cycling of ethanol both now and in the future as our use of the biofuel continues to grow.

  8. Phase Behavior and Physical Parameters of Natural Gas Mixture with CO2

    Directory of Open Access Journals (Sweden)

    Dali Hou

    2015-01-01

    Full Text Available The two-flash experiment, constant composition expansion experiment, saturation pressure measurement experiment, and phase transition observation experiment from well bottom hole to well head of four high CO2 content natural gas samples were carried out by using the JEFRI-PVT apparatus made from DBR Company of Canada. The experimental results show that in the four high CO2 content gas samples no phase transitions will take place at temperatures greater than 35°C. In the gas-liquid two-phase region, saturation pressures, critical pressure, critical temperature, and an integrated P-T phase diagram of different CO2 content natural gases are calculated by using the modified PR equation of state and modified (T equation proposed by Saffari. The deviations between the saturation pressure calculated by using the model proposed in this study and experimental measured saturation pressure are very small; the average relative error is only 2.86%. Thus, the model can be used to predict the phase equilibrium parameters of high CO2 content natural gas.

  9. Use of Flue Gas Desulfurization (FGD) Gypsum as a Heavy Metal Stabilizer in Contaminated Soils

    Science.gov (United States)

    Flue Gas Desulfurization (FGD) gypsum is a synthetic by-product generated from the flue gas desulfurization process in coal power plants. It has several beneficial applications such as an ingredient in cement production, wallboard production and in agricultural practice as a soil...

  10. Experimental on two sensors combination used in horizontal pipe gas-water two-phase flow

    International Nuclear Information System (INIS)

    Wu, Hao; Dong, Feng

    2014-01-01

    Gas-water two phase flow phenomenon widely exists in production and living and the measurement of it is meaningful. A new type of long-waist cone flow sensor has been designed to measure two-phase mass flow rate. Six rings structure of conductance probe is used to measure volume fraction and axial velocity. The calibration of them have been made. Two sensors have been combined in horizontal pipeline experiment to measure two-phase flow mass flow rate. Several model of gas-water two-phase flow has been discussed. The calculation errors of total mass flow rate measurement is less than 5% based on the revised homogeneous flow model

  11. Two phases of the anyon gas and broken T symmetry

    International Nuclear Information System (INIS)

    Canright, G.S.; Rojo, A.G.

    1991-01-01

    This paper reports the first exact finite-temperature study of anyons. The authors' method is an extension to finite T of earlier numerical work with small numbers of anyons on a lattice. We study the spontaneous magnetization M 0 (T), since the signature has been identified as a key signature of broken T symmetry for anyon models. Our results confirm the two-phase picture suggested by earlier work: The authors find a low-temperature regime where M 0 is very small or zero, and a high-temperature regime where M 0 is of O(0.1 μ B ) per particle. In the high-temperature regime the authors can obtain an excellent estimate of M 0 (T) in the thermodynamic limit (which we call M 0 ∞ ). since our finite-size results extrapolate smoothly with little scatter. The authors' values for M 0 ∞ can then be compared with the results of μSR experiments on high-temperature superconductors, which set an upper experimental bound on the internal fields from such moments. The authors find that M 0 ∞ in a bulk material of many planes will almost certainly give a signal well above this threshold if (and only if) the planes are ordered ferromagnetically. In the antiferromagnetic case (which is strongly favored energetically) the signal from M 0 ∞ is probably undetectable. Finally, we estimate the transition temperature T c from our finite-size studies, obtaining a value on the order of a few hundred Kelvins

  12. Isospin and momentum dependence of liquid-gas phase transition in hot asymmetric nuclear matter

    International Nuclear Information System (INIS)

    Xu, Jun; Ma, Hongru; Chen, Liewen; Li, Baoan

    2008-01-01

    The liquid-gas phase transition in hot neutron-rich nuclear matter is investigated within a self-consistent thermal model using different interactions with or without isospin and/or momentum dependence. The boundary of the phase-coexistence region is shown to be sensitive to the density dependence of the nuclear symmetry energy as well as the isospin and momentum dependence of the nuclear interaction. (author)

  13. Blood gas sample spiking with total parenteral nutrition, lipid emulsion, and concentrated dextrose solutions as a model for predicting sample contamination based on glucose result.

    Science.gov (United States)

    Jara-Aguirre, Jose C; Smeets, Steven W; Wockenfus, Amy M; Karon, Brad S

    2018-03-16

    Evaluate the effects of blood gas sample contamination with total parenteral nutrition (TPN)/lipid emulsion and dextrose 50% (D50) solutions on blood gas and electrolyte measurement; and determine whether glucose concentration can predict blood gas sample contamination with TPN/lipid emulsion or D50. Residual lithium heparin arterial blood gas samples were spiked with TPN/lipid emulsion (0 to 15%) and D50 solutions (0 to 2.5%). Blood gas (pH, pCO2, pO2), electrolytes (Na+, K+ ionized calcium) and hemoglobin were measured with a Radiometer ABL90. Glucose concentration was measured in separated plasma by Roche Cobas c501. Chart review of neonatal blood gas results with glucose >300 mg/dL (>16.65 mmol/L) over a seven month period was performed to determine whether repeat (within 4 h) blood gas results suggested pre-analytical errors in blood gas results. Results were used to determine whether a glucose threshold could predict contamination resulting in blood gas and electrolyte results with greater than laboratory-defined allowable error. Samples spiked with 5% or more TPN/lipid emulsion solution or 1% D50 showed glucose concentration >500 mg/dL (>27.75 mmol/L) and produced blood gas (pH, pO 2 , pCO 2 ) results with greater than laboratory-defined allowable error. TPN/lipid emulsion, but not D50, produced greater than allowable error in electrolyte (Na + ,K + ,Ca ++ ,Hb) results at these concentrations. Based on chart review of 144 neonatal blood gas results with glucose >250 mg/dL received over seven months, four of ten neonatal intensive care unit (NICU) patients with glucose results >500 mg/dL and repeat blood gas results within 4 h had results highly suggestive of pre-analytical error. Only 3 of 36 NICU patients with glucose results 300-500 mg/dL and repeat blood gas results within 4 h had clear pre-analytical errors in blood gas results. Glucose concentration can be used as an indicator of significant blood sample contamination with either TPN

  14. Oxidative potential of gas phase combustion emissions - An underestimated and potentially harmful component of air pollution from combustion processes

    Science.gov (United States)

    Stevanovic, S.; Vaughan, A.; Hedayat, F.; Salimi, F.; Rahman, M. M.; Zare, A.; Brown, R. A.; Brown, R. J.; Wang, H.; Zhang, Z.; Wang, X.; Bottle, S. E.; Yang, I. A.; Ristovski, Z. D.

    2017-06-01

    The oxidative potential (OP) of the gas phase is an important and neglected aspect of environmental toxicity. Whilst prolonged exposure to particulate matter (PM) associated reactive oxygen species (ROS) have been shown to lead to negative health effects, the potential for compounds in gas phase to cause similar effects is yet to be understood. In this study we describe: the significance of the gas phase OP generated through vehicle emissions; discuss the origin and evolution of species contributing to measured OP; and report on the impact of gas phase OP on human lung cells. The model aerosol for this study was exhaust emitted from a Euro III Common-rail diesel engine fuelled with different blends of diesel and biodiesel. The gas phase of these emissions was found to be potentially as hazardous as the particle phase. Fuel oxygen content was found to negatively correlate with the gas phase OP, and positively correlate with particle phase OP. This signifies a complex interaction between reactive species present in gas and particle phase. Furthermore, this interaction has an overarching effect on the OP of both particle and gas phase, and therefore the toxicity of combustion emissions.

  15. Gas-phase spectra of MgO molecules: a possible connection from gas-phase molecules to planet formation

    Science.gov (United States)

    Kloska, Katherine A.; Fortenberry, Ryan C.

    2018-02-01

    A more fine-tuned method for probing planet-forming regions, such as protoplanetary discs, could be rovibrational molecular spectroscopy observation of particular premineral molecules instead of more common but ultimately less related volatile organic compounds. Planets are created when grains aggregate, but how molecules form grains is an ongoing topic of discussion in astrophysics and planetary science. Using the spectroscopic data of molecules specifically involved in mineral formation could help to map regions where planet formation is believed to be occurring in order to examine the interplay between gas and dust. Four atoms are frequently associated with planetary formation: Fe, Si, Mg and O. Magnesium, in particular, has been shown to be in higher relative abundance in planet-hosting stars. Magnesium oxide crystals comprise the mineral periclase making it the chemically simplest magnesium-bearing mineral and a natural choice for analysis. The monomer, dimer and trimer forms of (MgO)n with n = 1-3 are analysed in this work using high-level quantum chemical computations known to produce accurate results. Strong vibrational transitions at 12.5, 15.0 and 16.5 μm are indicative of magnesium oxide monomer, dimer and trimer making these wavelengths of particular interest for the observation of protoplanetary discs and even potentially planet-forming regions around stars. If such transitions are observed in emission from the accretion discs or absorptions from stellar spectra, the beginning stages of mineral and, subsequently, rocky body formation could be indicated.

  16. Heavy-metal contamination and solid-phase fractionation in street dust.

    Science.gov (United States)

    Merrikhpour, Hajar; Mahdavi, Shahriar

    2017-09-03

    Fourteen street-dust samples were collected from Hamedan, western Iran. Street-dust samples received different amounts of heavy-metal pollution. The samples were analyzed for total cadmium (Cd), copper (Cu), lead (Pb), nickel (Ni), and zinc (Zn), and binding forms of heavy metal were determined in five fractions. The results showed Cd was the only metal present appreciably, 25.21% and 25.92%, in the exchangeable and carbonates fractions, respectively, and Cu was the only metal predominantly associated, 31.77%, with organic fraction. Zn, 45.84%, was present mainly in the Fe-Mn oxide fraction, and the residual fraction was the most dominant solid phase pool of Ni and Pb, respectively, with 42.56% and 41.31%. The order of apparent mobility and potential metal bioavailability for these contaminated street-dust samples is Cd > Zn > Cu > Pb > Ni. The risk-assessment code results showed very high risk for Cd; medium risk for Cu, Pb, and Zn; and low risk for Ni.

  17. De-oiled two-phase olive mill waste may reduce water contamination by metribuzin.

    Science.gov (United States)

    Peña, David; López-Piñeiro, Antonio; Albarrán, Ángel; Rato-Nunes, José Manuel; Sánchez-Llerena, Javier; Becerra, Daniel; Ramírez, Manuel

    2016-01-15

    The impact of de-oiled two-phase olive mill waste (DW) on the behavior of metribuzin in Mediterranean agricultural soils is evaluated, and the effects of the transformation of organic matter from this waste under field conditions are assessed. Four soils were selected and amended in the laboratory with DW at the rates of 2.5% and 5%. One of these soils was also amended in the field with 27 and 54 Mg ha(-1) of DW for 9 years. Significant increases in metribuzin sorption were observed in all the amended soils. In the laboratory, the 5% DW application rate increased the t1/2 values of metribuzin from 22.9, 35.8, 29.1, and 20.0 d for the original soils to 59.2, 51.1, 45.7, and 29.4d, respectively. This was attributable mainly to the inhibitory effect of the amendment on microbial activity. However, the addition of DW transformed naturally under field conditions decreased the persistence down to 3.93 d at the greater application rate. Both amendments (fresh and field-aged DW) significantly reduced the amount of metribuzin leached. This study showed that DW amendment may be an effective and sustainable management practice for controlling groundwater contamination by metribuzin. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. The influence of interfacial properties on the two-phase liquid flow of organic contaminants in groundwater

    International Nuclear Information System (INIS)

    Demond, A.H.; Desai, F.N.; Hayes, K.F.

    1992-01-01

    DOE's waste sites are contaminated with a variety of organic liquids. Because of their low solubility in water, organic liquids such as these will persist as separate liquid phases and be transported as such in the subsurface. Thus, an improved understanding of the factors influencing the movement of a separate organic liquid phase in the subsurface is important to DOE's efforts to control groundwater contamination. Wettability is sometimes cited as the most important factor influencing two-phase flow in porous media. The wetting phase migrates preferentially through the smaller pores, whereas the nonwetting phase is concentrated in the larger pores. Typically, aquifers are thought of as strongly water-wet, implying that the organic liquid preferentially occupies the larger pores. But in fact, that state depends on the properties of the three interfaces of the system: between the organic liquid and water, water and the solid, and the organic liquid and the solid. Characteristics of the system which affect the interfacial properties also impact the wettability, such as the nature of the aquifer solids' surfaces, the composition of the goundwater and the properties of the organic contaminant. The alteration of wettability at DOE waste sites may be dominated by the presence of co-contaminants such as organic acids and bases which behave as surface-active agents or surfactants. Because of their physicochemical nature, surfactants will sorb preferentially at the interfaces of the system, thereby impacting the wettability and the distribution of the liquids in the porous medium. The over-all objective of this research was to determine how changes in interfacial properties affect two-phase flow. Specifically, the objective was to examine the effect of surfactant sorption on capillary pressure relationships by correlating measurements of sorption, zeta potential, interfacial tension and contact angle, with changes in the capillary pressure-saturation relationships

  19. Formation routes of interstellar glycine involving carboxylic acids: possible favoritism between gas and solid phase.

    Science.gov (United States)

    Pilling, Sergio; Baptista, Leonardo; Boechat-Roberty, Heloisa M; Andrade, Diana P P

    2011-11-01

    Despite the extensive search for glycine (NH₂CH₂COOH) and other amino acids in molecular clouds associated with star-forming regions, only upper limits have been derived from radio observations. Nevertheless, two of glycine's precursors, formic acid and acetic acid, have been abundantly detected. Although both precursors may lead to glycine formation, the efficiency of reaction depends on their abundance and survival in the presence of a radiation field. These facts could promote some favoritism in the reaction pathways in the gas phase and solid phase (ice). Glycine and these two simplest carboxylic acids are found in many meteorites. Recently, glycine was also observed in cometary samples returned by the Stardust space probe. The goal of this work was to perform theoretical calculations for several interstellar reactions involving the simplest carboxylic acids as well as the carboxyl radical (COOH) in both gas and solid (ice) phase to understand which reactions could be the most favorable to produce glycine in interstellar regions fully illuminated by soft X-rays and UV, such as star-forming regions. The calculations were performed at four different levels for the gas phase (B3LYP/6-31G*, B3LYP/6-31++G**, MP2/6-31G*, and MP2/6-31++G**) and at MP2/6-31++G** level for the solid phase (ice). The current two-body reactions (thermochemical calculation) were combined with previous experimental data on the photodissociation of carboxylic acids to promote possible favoritism for glycine formation in the scenario involving formic and acetic acid in both gas and solid phase. Given that formic acid is destroyed more in the gas phase by soft X-rays than acetic acid is, we suggest that in the gas phase the most favorable reactions are acetic acid with NH or NH₂OH. Another possible reaction involves NH₂CH₂ and COOH, one of the most-produced radicals from the photodissociation of acetic acid. In the solid phase, we suggest that the reactions of formic acid with NH

  20. Magnetic resonance velocity imaging of liquid and gas two-phase flow in packed beds.

    Science.gov (United States)

    Sankey, M H; Holland, D J; Sederman, A J; Gladden, L F

    2009-02-01

    Single-phase liquid flow in porous media such as bead packs and model fixed bed reactors has been well studied by MRI. To some extent this early work represents the necessary preliminary research to address the more challenging problem of two-phase flow of gas and liquid within these systems. In this paper, we present images of both the gas and liquid velocities during stable liquid-gas flow of water and SF(6) within a packing of 5mm spheres contained within columns of diameter 40 and 27 mm; images being acquired using (1)H and (19)F observation for the water and SF(6), respectively. Liquid and gas flow rates calculated from the velocity images are in agreement with macroscopic flow rate measurements to within 7% and 5%, respectively. In addition to the information obtained directly from these images, the ability to measure liquid and gas flow fields within the same sample environment will enable us to explore the validity of assumptions used in numerical modelling of two-phase flows.

  1. Application of 'Hydration Model' to evaluate gas phase transfer of ruthenium and technetium from reprocessing solutions

    International Nuclear Information System (INIS)

    Sasahira, Akira; Hoshikawa, Tadahiro; Kamoshida, Mamoru; Kawamura, Fumio

    1994-01-01

    In order to evaluate the amounts of gas phase transferred ruthenium (Ru), and technetium (Tc), simulations were made for the continuous evaporator used in a reprocessing plant to concentrate high level liquid waste. The concentrations and activities of nitric acid and water, which controlled the reaction rate and gas-liquid equilibrium in the evaporator solution, were evaluated using the previously developed 'Hydration Model'. When the feed solution contained 2.7 M (=mol/dm 3 ) of nitric acid, the nitric acid concentration in the evaporator solution reached its maximum at the concentration factor (CF) of 6 (CF: concentration ratio of FPs in evaporator and feed solutions). The activities of nitric acid and water were saturated at values of 0.01 and 0.43, respectively, after the CF reached 6. The simulation predicted decontamination factors DFs of 2x10 5 and 8x10 3 for Ru and Tc, respectively, for a typical evaporation conditions with an operational pressure of 6,700 Pa, and FPs of 0.02 to 1.4 M. The simulation results agreed with the verification experiment within a factor of 2 for the amount of gas-phase transferred Ru during evaporation. The factor for the amount of gas-phase transferred Tc was estimated as 5 from the measurement error in the gas-liquid equilibrium constant. (author)

  2. Gas-Phase Growth of Heterostructures of Carbon Nanotubes and Bimetallic Nanowires

    Directory of Open Access Journals (Sweden)

    Whi Dong Kim

    2011-01-01

    Full Text Available A simple, inexpensive, and viable method for growing multiple heterostructured carbon nanotubes (CNTs over the entire surface of Ni-Al bimetallic nanowires (NWs in the gas phase was developed. Polymer-templated bimetallic nitrate NWs were produced by electrospinning in the first step, and subsequent calcination resulted in the formation of bimetallic oxide NWs by thermal decomposition. In the second step, free-floating bimetallic NWs were produced by spray pyrolysis in an environment containing hydrogen gas as a reducing gas. These NWs were continuously introduced into a thermal CVD reactor in order to grow CNTs in the gas phase. Scanning electron microscopy (SEM, transmission electron microscopy (TEM, and Raman spectrometry analyses revealed that the catalytic Ni sites exposed in the non-catalytic Al matrix over the entire surface of the bimetallic NWs were seeded to radially grow highly graphitized CNTs, which resembled “foxtail” structures. The grown CNTs were found to have a relatively uniform diameter of approximately 10±2 nm and 10 to 15 walls with a hollow core. The average length of the gas-phase-grown CNTs can be controlled between 100 and 1000 nm by adjusting the residence time of the free-floating bimetallic NWs in the thermal CVD reactor.

  3. Characterization of bacterial consortia for its use in bioremediation of gas-oil contaminated antarctic soils

    International Nuclear Information System (INIS)

    Ruberto, L.; Vazquez, S.; Mestre, C.; Nogales, B.; Christie-Oleza, J.; Bosch, R.; Mac Cormack, W. P.

    2009-01-01

    Success of bio augmentation of chronically-contaminated soils is controversial, mainly because the inocula are frequently unable to establish in the matrix under bioremediation. In Antarctica, the environmental conditions and the restriction for the introduction of non-autochthonous organisms (imposed by the Antarctic Treaty) prevent inoculation with foreign bacteria. (Author)

  4. Humidity independent mass spectrometry for gas phase chemical analysis via ambient proton transfer reaction.

    Science.gov (United States)

    Zhu, Hongying; Huang, Guangming

    2015-03-31

    In this work, a humidity independent mass spectrometric method was developed for rapid analysis of gas phase chemicals. This method is based upon ambient proton transfer reaction between gas phase chemicals and charged water droplets, in a reaction chamber with nearly saturate humidity under atmospheric pressure. The humidity independent nature enables direct and rapid analysis of raw gas phase samples, avoiding time- and sample-consuming sample pretreatments in conventional mass spectrometry methods to control sample humidity. Acetone, benzene, toluene, ethylbenzene and meta-xylene were used to evaluate the analytical performance of present method. The limits of detection for benzene, toluene, ethylbenzene and meta-xylene are in the range of ∼0.1 to ∼0.3 ppbV; that of benzene is well below the present European Union permissible exposure limit for benzene vapor (5 μg m(-3), ∼1.44 ppbV), with linear ranges of approximately two orders of magnitude. The majority of the homemade device contains a stainless steel tube as reaction chamber and an ultrasonic humidifier as the source of charged water droplets, which makes this cheap device easy to assemble and facile to operate. In addition, potential application of this method was illustrated by the real time identification of raw gas phase chemicals released from plants at different physiological stages. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Constructing a unique two-phase compressibility factor model for lean gas condensates

    Energy Technology Data Exchange (ETDEWEB)

    Moayyedi, Mahmood; Gharesheikhlou, Aliashghar [Research Institute of Petroleum Industry (RIPI), Tehran (Iran, Islamic Republic of); Azamifard, Arash; Mosaferi, Emadoddin [Amirkabir University of Technology (AUT), Tehran (Iran, Islamic Republic of)

    2015-02-15

    Generating a reliable experimental model for two-phase compressibility factor in lean gas condensate reservoirs has always been demanding, but it was neglected due to lack of required experimental data. This study presents the main results of constructing the first two-phase compressibility factor model that is completely valid for Iranian lean gas condensate reservoirs. Based on a wide range of experimental data bank for Iranian lean gas condensate reservoirs, a unique two-phase compressibility factor model was generated using design of experiments (DOE) method and neural network technique (ANN). Using DOE, a swift cubic response surface model was generated for two-phase compressibility factor as a function of some selected fluid parameters for lean gas condensate fluids. The proposed DOE and ANN models were finally validated using four new independent data series. The results showed that there is a good agreement between experimental data and the proposed models. In the end, a detailed comparison was made between the results of proposed models.

  6. DFT study of the reactions of Mo and Mo with CO2 in gas phase

    Indian Academy of Sciences (India)

    Abstract. Density functional theory (DFT) calculations have been performed to explore the potential energy surfaces of C–O bond activation in CO2 molecule by gas-phase Mo. + cation and Mo atom, in order to better understanding the mechanism of second-row metal reacting with CO2. The minimum energy reaction path is.

  7. Gas-phase infrared spectra of cationized nitrogen-substituted polycyclic aromatic hydrocarbons

    NARCIS (Netherlands)

    Galué, Alvaro; Pirali, O.; Oomens, J.

    2010-01-01

    Gas-phase infrared spectra of several ionized nitrogen substituted polycyclic aromatic hydrocarbons (PANHs) have been recorded in the 600-1600 cm(-1) region via IR multiple-photon dissociation (IRMPD) spectroscopy. The UV photoionized PANH ions are trapped and isolated in a quadrupole ion trap where

  8. Electron Attachment to the Gas Phase DNA Bases Cytosine and Thymine

    Czech Academy of Sciences Publication Activity Database

    Denifl, S.; Ptasiňska, S.; Probst, M.; Hrušák, Jan; Scheier, P.; Märk, T. D.

    2004-01-01

    Roč. 108, č. 31 (2004), s. 6562-6569 ISSN 1089-5639 R&D Projects: GA ČR GA203/02/0737 Institutional research plan: CEZ:AV0Z4040901 Keywords : gas-phase * cytosine * thymine Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.639, year: 2004

  9. Gas-phase infrared spectra of cationized nitrogen-substituted polycyclic aromatic hydrocarbons

    NARCIS (Netherlands)

    Galué, H.A.; Pirali, O.; Oomens, J.

    2010-01-01

    Gas-phase infrared spectra of several ionized nitrogen substituted polycyclic aromatic hydrocarbons (PANHs) have been recorded in the 600-1600 cm-1 region via IR multiple-photon dissociation (IRMPD) spectroscopy. The UV photoionized PANH ions are trapped and isolated in a quadrupole ion trap where

  10. Gas-phase UF6 enrichment monitor for enrichment plant safeguards

    International Nuclear Information System (INIS)

    Strittmatter, R.B.; Tape, J.W.

    1980-03-01

    An in-line enrichment monitor is being developed to provide real-time enrichment data for the gas-phase UF 6 feed stream of an enrichment plant. The nondestructive gamma-ray assay method can be used to determine the enrichment of natural UF 6 with a relative precision of better than 1% for a wide range of pressures

  11. Study of Iodine Behavior in the Gas Phase during a Severe Accident

    International Nuclear Information System (INIS)

    Kim, Hanchul; Cho, Yeonghun; Ryu, Myunghyun

    2014-01-01

    Among the iodine species, the organic iodides produced from the reaction between iodine and organics such as paint, are not easily trapped by the filters during the containment venting following a severe accident. Korea Institute of Nuclear Safety (KINS) has been studying this issue, joining international research programs such as ISTP-EPICUR, OECDBIP and OECD-STEM. In the course of this study, a simple iodine model, RAIM (Radio-Active Iodine chemistry Model) has been developed (Oh et al., 2011), based on the IMOD methodology, and other previous studies. This paper deals with our recent activities on this study, including the development of the model for the iodine reactions in gas phase. Iodine reactions in gas phase were modeled and added to the RAIM code, taking into account several relevant reactions such as formation of ARP, iodine oxide, and organic iodides in gas phase. RAIM was then applied to analyze the S2-6-5-2 test for which iodine-loaded coupons were tested in gas phase. The analysis results show a reasonable estimation of volatile iodine concentration with the desorption rate constant of about 10 -6 s -1 , while those of the other iodine species overestimated for the whole period of the test. It reveals the need to determine appropriate values for the rate constants for formation of iodine oxides and organic iodides

  12. Multiple Multidentate Halogen Bonding in Solution, in the Solid State, and in the (Calculated) Gas Phase.

    Science.gov (United States)

    Jungbauer, Stefan H; Schindler, Severin; Herdtweck, Eberhardt; Keller, Sandro; Huber, Stefan M

    2015-09-21

    The binding properties of neutral halogen-bond donors (XB donors) bearing two multidentate Lewis acidic motifs toward halides were investigated. Employing polyfluorinated and polyiodinated terphenyl and quaterphenyl derivatives as anion receptors, we obtained X-ray crystallographic data of the adducts of three structurally related XB donors with tetraalkylammonium chloride, bromide, and iodide. The stability of these XB complexes in solution was determined by isothermal titration calorimetry (ITC), and the results were compared to X-ray analyses as well as to calculated binding patterns in the gas phase. Density functional theory (DFT) calculations on the gas-phase complexes indicated that the experimentally observed distortion of the XB donors during multiple multidentate binding can be reproduced in 1:1 complexes with halides, whereas adducts with two halides show a symmetric binding pattern in the gas phase that is markedly different from the solid state structures. Overall, this study demonstrates the limitations in the transferability of binding data between solid state, solution, and gas phase in the study of complex multidentate XB donors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Operando Spectroscopy of the Gas-Phase Aldol Condensation of Propanal over Solid Base Catalysts

    NARCIS (Netherlands)

    Hernández-giménez, Ana M.; Ruiz-martínez, Javier; Puértolas, Begoña; Pérez-ramírez, Javier; Bruijnincx, Pieter C. A.; Weckhuysen, Bert M.

    2017-01-01

    The gas-phase aldol condensation of propanal, taken as model for the aldehyde components in bio-oils, has been studied with a combined operando set-up allowing to perform FT-IR & UV–Vis diffuse reflectance spectroscopy (DRS) with on-line mass spectrometry (MS). The selected solid base catalysts, a

  14. The 'sticky business' of cleaning gas-phase membrane proteins: a detergent oriented perspective.

    Science.gov (United States)

    Borysik, Antoni J; Robinson, Carol V

    2012-11-14

    In recent years the properties of gas-phase detergent clusters have come under close scrutiny due in part to their participation in the analysis of intact membrane protein complexes by mass spectrometry. The detergent molecules that cover the protein complex are removed in the gas-phase by thermally agitating the ions by collision-induced dissociation. This process however, is not readily controlled and can frequently result in the disruption of protein structure. Improved methods of releasing proteins from detergent clusters are clearly required. To facilitate this the structural properties of detergent clusters along with the mechanistic details of their dissociation need to be understood. Pivotal to understanding the properties of gas-phase detergent clusters is the technique of ion mobility mass spectrometry. This technique can be used to assign polydisperse detergent clusters and provide information about their geometries and packing densities. In this article we consider the shapes of detergent clusters and show that these clusters possess geometries that are inconsistent with those in solution. We analyse the distributions of clusters in detail using tandem mass spectrometry and suggest that the mean charge of clusters formed from certain detergents is governed by electrostatic repulsion. We discuss the dissociation of detergent clusters and propose that detergent evaporation it a key process in the protection of protein complexes during high energy collisions in the gas-phase.

  15. How Pt nanoparticles affect TiO2-induced gas-phase photocatalytic oxidation reactions

    NARCIS (Netherlands)

    Fraters, B.D.; Amrollahi Buky, Rezvaneh; Mul, Guido

    2015-01-01

    The effect of Pt nanoparticles on the gas-phase photocatalytic oxidation activity of TiO2 is shown to be largely dependent on the molecular functionality of the substrate. We demonstrate that Pt nanoparticles decrease rates in photocatalytic oxidation of propane, whereas a strong beneficial effect

  16. Gas phase polymerization of propylene. Reaction kinetics and molecular weight distribution

    NARCIS (Netherlands)

    Meier, G.B.; Weickert, G.; van Swaaij, Willibrordus Petrus Maria

    2001-01-01

    Gas-phase polymerizations have been executed at different temperatures, pressures, and hydrogen concentrations using Me2Si[Ind]2ZrCl2 / methylaluminoxane / SiO2(Pennsylvania Quarts) as a catalyst. The reaction rate curves have been described by a kinetic model, which takes into account the initially

  17. Hydrogen-deuterium exchange reactions of carbanions with D2O in the gas phase

    International Nuclear Information System (INIS)

    Stewart, J.H.; Shapiro, R.H.; DePuy, C.H.; Bierbaum, V.M.

    1977-01-01

    Using the flowing afterglow technique, we have observed that carbanions participate in sequential deuterium exchange reactions with D 2 O in the gas phase. The extent of exchange is reported for 32 carbanions and the mechanism of the reaction is discussed. The usefulness of this phenomenon as a probe of the acidity and structure of anions is described

  18. Regio-Selective Intramolecular Hydrogen/Deuterium Exchange in Gas-Phase Electron Transfer Dissociation

    Science.gov (United States)

    Hamuro, Yoshitomo

    2017-05-01

    Protein backbone amide hydrogen/deuterium exchange mass spectrometry (HDX-MS) typically utilizes enzymatic digestion after the exchange reaction and before MS analysis to improve data resolution. Gas-phase fragmentation of a peptic fragment prior to MS analysis is a promising technique to further increase the resolution. The biggest technical challenge for this method is elimination of intramolecular hydrogen/deuterium exchange (scrambling) in the gas phase. The scrambling obscures the location of deuterium. Jørgensen's group pioneered a method to minimize the scrambling in gas-phase electron capture/transfer dissociation. Despite active investigation, the mechanism of hydrogen scrambling is not well-understood. The difficulty stems from the fact that the degree of hydrogen scrambling depends on instruments, various parameters of mass analysis, and peptide analyzed. In most hydrogen scrambling investigations, the hydrogen scrambling is measured by the percentage of scrambling in a whole molecule. This paper demonstrates that the degree of intramolecular hydrogen/deuterium exchange depends on the nature of exchangeable hydrogen sites. The deuterium on Tyr amide of neurotensin (9-13), Arg-Pro-Tyr-Ile-Leu, migrated significantly faster than that on Ile or Leu amides, indicating the loss of deuterium from the original sites is not mere randomization of hydrogen and deuterium but more site-specific phenomena. This more precise approach may help understand the mechanism of intramolecular hydrogen exchange and provide higher confidence for the parameter optimization to eliminate intramolecular hydrogen/deuterium exchange during gas-phase fragmentation.

  19. Supported Rh-phosphine complex catalysts for continuous gas-phase decarbonylation of aldehydes

    DEFF Research Database (Denmark)

    Malcho, Phillip; Garcia-Suarez, Eduardo J.; Mentzel, Uffe Vie

    2014-01-01

    Heterogeneous silica supported rhodium-phosphine complex catalysts are employed for the first time in the catalytic decarbonylation of aldehydes in continuous gas-phase. The reaction protocol is exemplified for the decarbonylation of p-tolualdehyde to toluene and further extended to other aromati...

  20. DFT study of the reactions of Mo and Mo with CO 2 in gas phase

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 3. DFT study of the reactions of Mo and Mo+ with CO2 in gas phase. Deman Han Guoliang Dai Hao Chen Hua Yan Junyong Wu Chuanfeng Wang Aiguo Zhong. Volume 123 Issue 3 May 2011 pp 299-309 ...

  1. Structure analysis of large argon clusters from gas-phase electron diffraction data: some recent results

    NARCIS (Netherlands)

    van de Waal, B.W.

    1999-01-01

    An up-to-date overview of recent developments in the structure elucidation of large ArN-clusters (103gas-phase electron diffraction data, is given. Although a satisfactory model for N3000 had been found in 1996, the size range beyond N10,000 presents new and unexpected problems.

  2. Gas-phase salt bridge interactions between glutamic acid and arginine

    NARCIS (Netherlands)

    Jaeqx, S.; Oomens, J.; Rijs, A.M.

    2013-01-01

    The gas-phase side chain-side chain (SC-SC) interaction and possible proton transfer between glutamic acid (Glu) and arginine (Arg) residues are studied under low-temperature conditions in an overall neutral peptide. Conformation-specific IR spectra, obtained with the free electron laser FELIX, in

  3. Gas-phase photoemission with soft x-rays: cross sections and angular distributions

    International Nuclear Information System (INIS)

    Shirley, D.A.; Kobrin, P.H.; Truesdale, C.M.; Lindle, D.W.; Ferrett, T.A.; Heimann, P.A.; Becker, U.; Kerkhoff, H.G.; Southworth, S.H.

    1983-09-01

    A summary is presented of typical gas-phase photoemission studies based on synchrotron radiation in the 50-5000 eV range, using beam lines at the Stanford Synchrotron Radiation Laboratory. Three topics are addressed: atomic inner-shell photoelectron cross sections and asymmetries, correlation peaks in rare gases, and core-level shape resonances in molecules

  4. Ab initio study of gas phase and water-assisted tautomerization of ...

    Indian Academy of Sciences (India)

    WINTEC

    Water-assisted tautomerization in maleimide and formamide showed that difference in energy barrier reduces to 2⋅83 kcal/mol from 10⋅41 kcal/mol (in gas phase) at B3LYP level, which resulted that maleimide readily undergoes tautomerization in water molecule. Keywords. Ab Initio calculations; maleimide; formamide; ...

  5. The Significance of Gas-Phase Mass Transport in Assessment of kchem and Dchem

    DEFF Research Database (Denmark)

    Lohne, Ørjan Fossmark; Søgaard, Martin; Wiik, Kjell

    2013-01-01

    In this work, the validity of electrical conductivity relaxation (ECR) as a method for the assessment of chemical surface exchange, kchem, and bulk diffusion, Dchem, coefficients is investigated with respect to mass transport limitations in the gas phase. A model encompassing both the oxygen...

  6. Role of isospin in nuclear-matter liquid-gas phase transition

    International Nuclear Information System (INIS)

    Ducoin, C.

    2006-10-01

    Nuclear matter presents a phase transition of the liquid-gas type. This well-known feature is due to the nuclear interaction profile (mean-range attractive, short-range repulsive). Symmetric-nuclear-matter thermodynamics is thus analogous to that of a Van der Waals fluid. The study shows up to be more complex in the case of asymmetric matter, composed of neutrons and protons in an arbitrary proportion. Isospin, which distinguishes both constituents, gives a measure of this proportion. Studying asymmetric matter, isospin is an additional degree of freedom, which means one more dimension to consider in the space of observables. The nuclear liquid-gas transition is associated with the multi-fragmentation phenomenon observed in heavy-ion collisions, and to compact-star physics: the involved systems are neutron rich, so they are affected by the isospin degree of freedom. The present work is a theoretical study of isospin effects which appear in the asymmetric nuclear matter liquid-gas phase transition. A mean-field approach is used, with a Skyrme nuclear effective interaction. We demonstrate the presence of a first-order phase transition for asymmetric matter, and study the isospin distillation phenomenon associated with this transition. The case of phase separation at thermodynamic equilibrium is compared to spinodal decomposition. Finite size effects are addressed, as well as the influence of the electron gas which is present in the astrophysical context. (author)

  7. Imaging Molecular Structure through Femtosecond Photoelectron Diffraction on Aligned and Oriented Gas-Phase Molecules

    DEFF Research Database (Denmark)

    Boll, Rebecca; Rouzee, Arnaud; Adolph, Marcus

    2014-01-01

    This paper gives an account of our progress towards performing femtosecond time-resolved photoelectron diffraction on gas-phase molecules in a pump-probe setup combining optical lasers and an X-ray Free-Electron Laser. We present results of two experiments aimed at measuring photoelectron angular...

  8. Modeling of Shale Gas Adsorption and its Influence on Phase Equilibrium

    DEFF Research Database (Denmark)

    Sandoval Lemus, Diego Rolando; Yan, Wei; Michelsen, Michael Locht

    2018-01-01

    Natural gas and oil produced from shale accounts for a signicant portion in the global production. Due to the large surface area and high organic content in shale formations, adsorption plays a major role in the storage of the hydrocarbons within the rock and their phase equilibrium. This study...

  9. Constructing a unique two-phase compressibility factor model for lean gas condensates

    International Nuclear Information System (INIS)

    Moayyedi, Mahmood; Gharesheikhlou, Aliashghar; Azamifard, Arash; Mosaferi, Emadoddin

    2015-01-01

    Generating a reliable experimental model for two-phase compressibility factor in lean gas condensate reservoirs has always been demanding, but it was neglected due to lack of required experimental data. This study presents the main results of constructing the first two-phase compressibility factor model that is completely valid for Iranian lean gas condensate reservoirs. Based on a wide range of experimental data bank for Iranian lean gas condensate reservoirs, a unique two-phase compressibility factor model was generated using design of experiments (DOE) method and neural network technique (ANN). Using DOE, a swift cubic response surface model was generated for two-phase compressibility factor as a function of some selected fluid parameters for lean gas condensate fluids. The proposed DOE and ANN models were finally validated using four new independent data series. The results showed that there is a good agreement between experimental data and the proposed models. In the end, a detailed comparison was made between the results of proposed models

  10. Gas-phase advanced oxidation for effective, efficient in situ control of pollution

    DEFF Research Database (Denmark)

    Johnson, Matthew Stanley; Nilsson, Elna Johanna Kristina; Svensson, Erik Anders

    2014-01-01

    In this article, gas-phase advanced oxidation, a new method for pollution control building on the photo-oxidation and particle formation chemistry occurring in the atmosphere, is introduced and characterized. The process uses ozone and UV-C light to produce in situ radicals to oxidize pollution...

  11. Characterization of odorous contaminants in post-consumer plastic packaging waste using multidimensional gas chromatographic separation coupled with olfactometric resolution.

    Science.gov (United States)

    Strangl, Miriam; Fell, Tanja; Schlummer, Martin; Maeurer, Andreas; Buettner, Andrea

    2017-04-01

    The increasing world population with their growing consumption of goods escalates the issue of sustainability concepts with increasing demands in recycling technologies. Recovery of post-consumer packaging waste is a major topic in this respect. However, contamination with odorous constituents currently curtails the production of recycling products that meet the high expectations of both consumers and industry. To guarantee odor-free recyclates, the main prerequisite is to characterize the molecular composition of the causative odorants in post-consumer plastic packaging waste. However, targeted characterization of odorous trace contaminants among an abundance of volatiles is a major challenge and requires specialized and high-resolution analytical approaches. For this aim, post-consumer packaging waste was characterized by sensory analysis and two-dimensional high resolution gas chromatography coupled with mass spectrometry and olfactometry. The 33 identified odorants represent various structural classes as well as a great diversity of smell impressions with some of the compounds being identified in plastics for the first time. Substances unraveled within this study provide insights into sources of odorous contamination that will require specific attention in the future in terms of screening and prevention in recycling products. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. On the phase-correlation and phase-fluctuation dynamics of a strongly excited Bose gas

    Energy Technology Data Exchange (ETDEWEB)

    Sakhel, Roger R., E-mail: rogersakhel@yahoo.com [Department of Basic Sciences, Faculty of Information Technology, Isra University, Amman 11622 (Jordan); The Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, Trieste 34151 (Italy); Sakhel, Asaad R. [Department of Applied Sciences, Faculty of Engineering Technology, Balqa Applied University, Amman 11134 (Jordan); The Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, Trieste 34151 (Italy); Ghassib, Humam B. [Department of Physics, The University of Jordan, Amman 11942 (Jordan)

    2015-12-01

    The dynamics of a Bose–Einstein condensate (BEC) is explored in the wake of a violent excitation caused by a strong time-dependent deformation of a trapping potential under the action of an intense stirring laser. The system is a two-dimensional BEC confined to a power-law trap with hard-wall boundaries. The stirring agent is a moving red-detuned laser potential. The time-dependent Gross–Pitaevskii equation is solved numerically by the split-step Crank–Nicolson method in real time. The phase correlations and phase fluctuations are examined as functions of time to demonstrate the evolving properties of a strongly-excited BEC. Of special significance is the occurrence of spatial fluctuations while the condensate is being excited. These oscillations arise from stirrer-induced density fluctuations. While the stirrer is inside the trap, a reduction in phase coherence occurs, which is attributed to phase fluctuations.

  13. Structure of the gas-liquid annular two-phase flow in a nozzle section

    International Nuclear Information System (INIS)

    Yoshida, Kenji; Kataoka, Isao; Ohmori, Syuichi; Mori, Michitsugu

    2006-01-01

    Experimental studies on the flow behavior of gas-liquid annular two-phase flow passing through a nozzle section were carried out. This study is concerned with the central steam jet injector for a next generation nuclear reactor. In the central steam jet injector, steam/water annular two-phase flow is formed at the mixing nozzle. To make an appropriate design and to establish the high-performance steam injector system, it is very important to accumulate the fundamental data of the thermo-hydro dynamic characteristics of annular flow passing through a nozzle section. On the other hand, the transient behavior of multiphase flow, in which the interactions between two-phases occur, is one of the most interesting scientific issues and has attracted research attention. In this study, the transient gas-phase turbulence modification in annular flow due to the gas-liquid phase interaction is experimentally investigated. The annular flow passing through a throat section is under the transient state due to the changing cross sectional area of the channel and resultantly the superficial velocities of both phases are changed compared with a fully developed flow in a straight pipe. The measurements for the gas-phase turbulence were precisely performed by using a constant temperature hot-wire anemometer, and made clear the turbulence structure such as velocity profiles, fluctuation velocity profiles. The behavior of the interfacial waves in the liquid film flow such as the ripple or disturbance waves was also observed. The measurements for the liquid film thickness by the electrode needle method were also performed to measure the base film thickness, mean film thickness, maximum film thickness and wave height of the ripple or the disturbance waves. (author)

  14. Investigation of contamination caused by rubber compactor in arsine purified in gas centrifuge

    OpenAIRE

    Zaykov, А. А.; Zyryanov, S. М.; Kulinich, Yu. А.; Pulnikov, I. I.; Skorynin, G. М.; Vlasov, V. А.

    2007-01-01

    In the process of studying the application of gas centrifuges for deep purification of arsine from impurities sulphur was found. Estimation of quantitative content of sulphur in pure arsine showed the value -10-4 wt. %. The sources of sulphur was stated to be rubber compactors forming gas centrifuge complex and made from rubber on the basis of butadiene_nitrile caoutchouc using sulfur cure. Using rubber compactors made from rubber produced from fluoroelastomers, not undergoing to sulfur cure ...

  15. Influence of structured packing on gas holdup in a three-phase bubble column

    DEFF Research Database (Denmark)

    Monsalvo, Matias Alfonso; Böhm, Ursula

    2007-01-01

    In this work, the influence of structured packing on gas holdup in gas-liquid-solid dispersions has been studied. The experiments were carried out in an empty column and in column containing structured packing operating under identical conditions. Glass beads and silicon carbide particles were used...... as the solid material and the volumetric fraction of solids was varied from 0% to around 10%. The liquid viscosity was strongly modified using water, CMC solution and glycerol. The experimental results obtained with both columns were compared with previous results obtained in two-phase bubble columns...... the results obtained with glycerol, these correlations can predict the gas holdup of three-phase bubble columns with reasonable accuracy. (C) 2007 Elsevier Ltd. All rights reserved....

  16. Finite-time thermodynamics and the gas-liquid phase transition.

    Science.gov (United States)

    Santoro, M; Schön, J C; Jansen, M

    2007-12-01

    In this paper, we study the application of the concept of finite-time thermodynamics to first-order phase transitions. As an example, we investigate the transition from the gaseous to the liquid state by modeling the liquification of the gas in a finite time. In particular, we introduce, state, and solve an optimal control problem in which we aim at achieving the gas-liquid first-order phase transition through supersaturation within a fixed time in an optimal fashion, in the sense that the work required to supersaturate the gas, called excess work, is minimized by controlling the appropriate thermodynamic parameters. The resulting set of coupled nonlinear differential equations is then solved for three systems, nitrogen N2, oxygen O2, and water vapor H2O.

  17. Partitioning of phthalates among the gas phase, airborne particles and settled dust in indoor environments

    DEFF Research Database (Denmark)

    Weschler, Charles J.; Salthammer, Tunga; Fromme, Hermann

    2008-01-01

    A critical evaluation of human exposure to phthalate esters in indoor environments requires the determination of their distribution among the gas phase, airborne particles and settled dust. If sorption from the gas phase is the dominant mechanism whereby a given phthalate is associated with both...... airborne particles and settled dust, there should be a predictable relationship between its particle and dust concentrations. The present paper tests this for six phthalate esters (DMP, DEP, DnBP, DiBP, BBzP and DEHP) that have been measured in both the air and the settled dust of 30 Berlin apartments....... The particle concentration, C-particle, of a given phthalate was calculated from its total airborne concentration and the concentration of airborne particles (PM4). This required knowledge of the particle-gas partition coefficient, K., which was estimated from either the saturation vapor pressure (p...

  18. Measurement of gas hold-up in three-phase systems by ultrasonic technique

    Energy Technology Data Exchange (ETDEWEB)

    Maezawa, Akinori (Graduate School of Electronic Science and Technology, Shizuoka Univ., Hamamatsu (Japan)); Muramatsu, Shingo (Dept. of Chemical Engineering, Shizuoka Univ., Hamamatsu (Japan)); Uchida, Shigeo (Dept. of Chemical Engineering, Shizuoka Univ., Hamamatsu (Japan)); Okamura, Seichi (Dept. of Electronic Engineering, Shizuoka Univ., Hamamatsu (Japan))

    1993-08-01

    It was established by using double impulse method that the transmission time of an ultrasonic wave, which passes near a bubble, is either shorter or longer than that in the liquid system. This is attributed to the fluid vortex originated by the bubble rising ahead of the wave. The longitudinal distribution of gas hold-up in a three-phase system, measured by analyzing wave shape and reduction of transmission time is in good agreement with that obtained by using the static pressure method. This indicates the possibility of application of ultrasonic techniques to the simultaneous measurement of phase hold-ups in the three-phase system. (orig.)

  19. In-line gas chromatographic apparatus for measuring the hydrophobic micropore volume (HMV) and contaminant transformation in mineral micropores.

    Science.gov (United States)

    Cheng, Hefa; Reinhard, Martin

    2010-07-15

    Desorption of hydrophobic organic compounds from micropores is characteristically slow compared to surface adsorption and partitioning. The slow-desorbing mass of a hydrophobic probe molecule can be used to calculate the hydrophobic micropore volume (HMV) of microporous solids. A gas chromatographic apparatus is described that allows characterization of the sorbed mass with respect to the desorption rate. The method is demonstrated using a dealuminated zeolite and an aquifer sand as the model and reference sorbents, respectively, and trichloroethylene (TCE) as the probe molecule. A glass column packed with the microporous sorbent is coupled directly to a gas chromatograph that is equipped with flame ionization and electron capture detectors. Sorption and desorption of TCE on the sorbent was measured by sampling the influent and effluent of the column using a combination of switching and injection valves. For geosorbents, the HMV is quantified based on Gurvitsch's rule from the mass of TCE desorbed at a rate that is characteristic for micropores. Instrumental requirements, design considerations, hardware details, detector calibration, performance, and data analysis are discussed along with applications. The method is novel and complements traditional vacuum gravimetric and piezometric techniques, which quantify the total pore volume under vacuum conditions. The HMV is more relevant than the total micropore volume for predicting the fate and transport of organic contaminants in the subsurface. Sorption in hydrophobic micropores strongly impacts the mobility of organic contaminants, and their chemical and biological transformations. The apparatus can serve as a tool for characterizing microporous solids and investigating contaminant-solid interactions. 2010 Elsevier B.V. All rights reserved.

  20. Comparative simulation study of gas-phase propylene polymerization in fluidized bed reactors using aspen polymers and two phase models

    Directory of Open Access Journals (Sweden)

    Shamiria Ahmad

    2013-01-01

    Full Text Available A comparative study describing gas-phase propylene polymerization in fluidized-bed reactors using Ziegler-Natta catalyst is presented. The reactor behavior was explained using a two-phase model (which is based on principles of fluidization as well as simulation using the Aspen Polymers process simulator. The two-phase reactor model accounts for the emulsion and bubble phases which contain different portions of catalysts with the polymerization occurring in both phases. Both models predict production rate, molecular weight, polydispersity index (PDI and melt flow index (MFI of the polymer. We used both models to investigate the effect of important polymerization parameters, namely catalyst feed rate and hydrogen concentration, on the product polypropylene properties, such as production rate, molecular weight, PDI and MFI. Both the two-phase model and Aspen Polymers simulator showed good agreement in terms of production rate. However, the models differed in their predictions for weight-average molecular weight, PDI and MFI. Based on these results, we propose incorporating the missing hydrodynamic effects into Aspen Polymers to provide a more realistic understanding of the phenomena encountered in fluidized bed reactors for polyolefin production.

  1. Are ionic liquids pairwise in gas phase? A cluster approach and in situ IR study.

    Science.gov (United States)

    Dong, Kun; Zhao, Lidong; Wang, Qian; Song, Yuting; Zhang, Suojiang

    2013-04-28

    In this work, we discussed the vaporization and gas species of ionic liquids (ILs) by a cluster approach of quantum statistical thermodynamics proposed by R. Luwig (Phys. Chem. Chem. Phys., 10, 4333), which is a controversial issue up to date. Based on the different sized clusters (2-12 ion-pairs) of the condensed phase, the molar enthalpies of vaporization (ΔvapH, 298.15 K, 1bar) of four representative ILs, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][NTf2]) 1-ethyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ([Emmim][NTf2]) 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) and ethylammonium nitrate ([EtAm][NO3]), were calculated. The predicted ΔvapH were increased remarkably; even the values of [EtAm][NO3] were larger than 700 kJ mol(-1) when the charged isolated ions were assumed to be gas species. However, the ΔvapH were close to experimental measurements when the gas species assumed to be anion-cation pairwise, indicating that the different conformational ion-pairs can coexist in the gas phase when the IL is evaporated. Particularly for the protic IL, [EtAm][NO3], even the neutral precursor molecules by proton transfer can occur in gas phase. In addition, it's found that the effect of hydrogen bonds on the vaporization cannot be negligible by comparing the ΔvapH of [Emim][NTf2] with [Emmim][NTf2]. The in situ and calculated IR spectra provided the further proof that the ions are pairwise in gas phase.

  2. The Genealogical Tree of Ethanol: Gas-phase Formation of Glycolaldehyde, Acetic Acid, and Formic Acid

    Science.gov (United States)

    Skouteris, Dimitrios; Balucani, Nadia; Ceccarelli, Cecilia; Vazart, Fanny; Puzzarini, Cristina; Barone, Vincenzo; Codella, Claudio; Lefloch, Bertrand

    2018-02-01

    Despite the harsh conditions of the interstellar medium, chemistry thrives in it, especially in star-forming regions where several interstellar complex organic molecules (iCOMs) have been detected. Yet, how these species are synthesized is a mystery. The majority of current models claim that this happens on interstellar grain surfaces. Nevertheless, evidence is mounting that neutral gas-phase chemistry plays an important role. In this paper, we propose a new scheme for the gas-phase synthesis of glycolaldehyde, a species with a prebiotic potential and for which no gas-phase formation route was previously known. In the proposed scheme, the ancestor is ethanol and the glycolaldehyde sister species are acetic acid (another iCOM with unknown gas-phase formation routes) and formic acid. For the reactions of the new scheme with no available data, we have performed electronic structure and kinetics calculations deriving rate coefficients and branching ratios. Furthermore, after a careful review of the chemistry literature, we revised the available chemical networks, adding and correcting several reactions related to glycolaldehyde, acetic acid, and formic acid. The new chemical network has been used in an astrochemical model to predict the abundance of glycolaldehyde, acetic acid, and formic acid. The predicted abundance of glycolaldehyde depends on the ethanol abundance in the gas phase and is in excellent agreement with the measured one in hot corinos and shock sites. Our new model overpredicts the abundance of acetic acid and formic acid by about a factor of 10, which might imply a yet incomplete reaction network.

  3. Gas-phase metalloprotein complexes interrogated by ion mobility-mass spectrometry

    Science.gov (United States)

    Faull, Peter A.; Korkeila, Karoliina E.; Kalapothakis, Jason M.; Gray, Andrew; McCullough, Bryan J.; Barran, Perdita E.

    2009-06-01

    Gas-phase biomolecular structure may be explored through a number of analytical techniques. Ion mobility-mass spectrometry (IM-MS) continues to prove itself as a sensitive and reliable bioanalytical tool for gas-phase structure determination due to intense study and development over the past 15 years. A vast amount of research interest, especially in protein and peptide conformational studies has generated a wealth of structural information for biological systems from small peptides to megadalton-sized biomolecules. In this work, linear low field IM-MS has been used to study gas-phase conformations and determine rotationally averaged collision cross-sections of three metalloproteins--cytochrome c, haemoglobin and calmodulin. Measurements have been performed on the MoQToF, a modified QToF 1 instrument (Micromass UK Ltd., Manchester, UK) modified in house. Gas-phase conformations and cross-sections of multimeric cytochrome c ions of the form [xM + nH+]n+ for x = 1-3 (monomer to trimer) have been successfully characterised and measured. We believe these to be the first reported collision cross-sections of higher order multimeric cytochrome c. Haemoglobin is investigated to obtain structural information on the associative mechanism of tetramer formation. Haemoglobin molecules, comprising apo- and holo-monomer chains, dimer and tetramer are transferred to the gas phase under a range of solution conditions. Structural information on the proposed critical intermediate, semi-haemoglobin, is reported. Cross-sections of the calcium binding protein calmodulin have been obtained under a range of calcium-bound conditions. Metalloprotein collision cross-sections from ion mobility measurements are compared with computationally derived values from published NMR and X-ray crystallography structural data. Finally we consider the change in the density of the experimentally measured rotationally averaged collision cross-section for compact geometries of the electrosprayed proteins.

  4. Diffusion Monte Carlo simulations of gas phase and adsorbed D2-(H2)n clusters

    Science.gov (United States)

    Curotto, E.; Mella, M.

    2018-03-01

    We have computed ground state energies and analyzed radial distributions for several gas phase and adsorbed D2(H2)n and HD(H2)n clusters. An external model potential designed to mimic ionic adsorption sites inside porous materials is used [M. Mella and E. Curotto, J. Phys. Chem. A 121, 5005 (2017)]. The isotopic substitution lowers the ground state energies by the expected amount based on the mass differences when these are compared with the energies of the pure clusters in the gas phase. A similar impact is found for adsorbed aggregates. The dissociation energy of D2 from the adsorbed clusters is always much higher than that of H2 from both pure and doped aggregates. Radial distributions of D2 and H2 are compared for both the gas phase and adsorbed species. For the gas phase clusters, two types of hydrogen-hydrogen interactions are considered: one based on the assumption that rotations and translations are adiabatically decoupled and the other based on nonisotropic four-dimensional potential. In the gas phase clusters of sufficiently large size, we find the heavier isotopomer more likely to be near the center of mass. However, there is a considerable overlap among the radial distributions of the two species. For the adsorbed clusters, we invariably find the heavy isotope located closer to the attractive interaction source than H2, and at the periphery of the aggregate, H2 molecules being substantially excluded from the interaction with the source. This finding rationalizes the dissociation energy results. For D2-(H2)n clusters with n ≥12 , such preference leads to the desorption of D2 from the aggregate, a phenomenon driven by the minimization of the total energy that can be obtained by reducing the confinement of (H2)12. The same happens for (H2)13, indicating that such an effect may be quite general and impact on the absorption of quantum species inside porous materials.

  5. Product energy deposition of CN + alkane H abstraction reactions in gas and solution phases

    Science.gov (United States)

    Glowacki, David R.; Orr-Ewing, Andrew J.; Harvey, Jeremy N.

    2011-06-01

    In this work, we report the first theoretical studies of post-transition state dynamics for reaction of CN with polyatomic organic species. Using electronic structure theory, a newly developed analytic reactive PES, a recently implemented rare-event acceleration algorithm, and a normal mode projection scheme, we carried out and analyzed quasi-classical and classical non-equilibrium molecular dynamics simulations of the reactions CN + propane (R1) and CN + cyclohexane (R2). For (R2), we carried out simulations in both the gas phase and in a CH2Cl2 solvent. Analysis of the results suggests that the solvent perturbations to the (R2) reactive free energy surface are small, leading to product energy partitioning in the solvent that is similar to the gas phase. The distribution of molecular geometries at the respective gas and solution phase variational association transition states is very similar, leading to nascent HCN which is vibrationally excited in both its CH stretching and HCN bending coordinates. This study highlights the fact that significant non-equilibrium energy distributions may follow in the wake of solution phase bimolecular reactions, and may persist for hundreds of picoseconds despite frictional damping. Consideration of non-thermal distributions is often neglected in descriptions of condensed-phase reactivity; the extent to which the present intriguing observations are widespread remains an interesting question.

  6. Lattice model theory of the equation of state covering the gas, liquid, and solid phases

    Science.gov (United States)

    Bonavito, N. L.; Tanaka, T.; Chan, E. M.; Horiguchi, T.; Foreman, J. C.

    1975-01-01

    The three stable states of matter and the corresponding phase transitions were obtained with a single model. Patterned after Lennard-Jones and Devonshires's theory, a simple cubic lattice model containing two fcc sublattices (alpha and beta) is adopted. The interatomic potential is taken to be the Lennard-Jones (6-12) potential. Employing the cluster variation method, the Weiss and the pair approximations on the lattice gas failed to give the correct phase diagrams. Hybrid approximations were devised to describe the lattice term in the free energy. A lattice vibration term corresponding to a free volume correction is included semi-phenomenologically. The combinations of the lattice part and the free volume part yield the three states and the proper phase diagrams. To determine the coexistence regions, the equalities of the pressure and Gibbs free energy per molecule of the coexisting phases were utilized. The ordered branch of the free energy gives rise to the solid phase while the disordered branch yields the gas and liquid phases. It is observed that the triple point and the critical point quantities, the phase diagrams and the coexistence regions plotted are in good agreement with the experimental values and graphs for argon.

  7. Radiation Resistant Hybrid Lotus Effect Photoelectrocatalytic Self-Cleaning Anti-Contamination Coatings, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop radiation resistant hybrid Lotus Effect photoelectrocatalytic self-cleaning anti-contamination coatings for application to Lunar...

  8. Effect of duty-cycles on the air plasma gas-phase of dielectric barrier discharges

    Science.gov (United States)

    Barni, R.; Biganzoli, I.; Dell'Orto, E. C.; Riccardi, C.

    2015-10-01

    An experimental investigation concerning the effects of a duty-cycle in the supply of a dielectric barrier discharge in atmospheric pressure air has been performed. Electrical characteristics of the discharge have been measured, focusing mainly on the statistical properties of the current filaments and on dielectric surface charging, both affected by the frequent repetition of breakdown imposed by the duty-cycle. Information on the gas-phase composition was gathered too. In particular, a strong enhancement in the ozone formation rate is observed when suitable long pauses separate the active discharge phases. A simulation of the chemical kinetics in the gas-phase, based on a simplified discharge modeling, is briefly described in order to shed light on the observed increase in ozone production. The effect of a duty-cycle on surface modification of polymeric films in order to increase their wettability has been investigated too.

  9. LANDFILL GAS CONVERSION TO LNG AND LCO{sub 2}. PHASE 1, FINAL REPORT FOR THE PERIOD MARCH 1998-FEBRUARY 1999

    Energy Technology Data Exchange (ETDEWEB)

    COOK,W.J.; NEYMAN,M.; SIWAJEK,L.A.; BROWN,W.R.; VAN HAUWAERT,P.M.; CURREN,E.D.

    1998-02-25

    Process designs and economics were developed to produce LNG and liquid carbon dioxide (CO{sub 2}) from landfill gas (LFG) using the Acrion CO{sub 2} wash process. The patented Acrion CO{sub 2} wash process uses liquid CO{sub 2} to absorb contaminants from the LFG. The process steps are compression, drying, CO{sub 2} wash contaminant removal and CO{sub 2} recovery, residual CO{sub 2} removal and methane liquefaction. Three flowsheets were developed using different residual CO{sub 2} removal schemes. These included physical solvent absorption (methanol), membranes and molecular sieves. The capital and operating costs of the flowsheets were very similar. The LNG production cost was around ten cents per gallon. In parallel with process flowsheet development, the business aspects of an eventual commercial project have been explored. The process was found to have significant potential commercial application. The business plan effort investigated the economics of LNG transportation, fueling, vehicle conversion, and markets. The commercial value of liquid CO{sub 2} was also investigated. This Phase 1 work, March 1998 through February 1999, was funded under Brookhaven National laboratory contract 725089 under the research program entitled ``Liquefied Natural Gas as a Heavy Vehicle Fuel.'' The Phase 2 effort will develop flowsheets for the following: (1) CO{sub 2} and pipeline gas production, with the pipeline methane being liquefied at a peak shaving site, (2) sewage digester gas as an alternate feedstock to LFG and (3) the use of mixed refrigerants for process cooling. Phase 2 will also study the modification of Acrion's process demonstration unit for the production of LNG and a market site for LNG production.

  10. Site-specific analysis of gas-phase hydrogen/deuterium exchange of peptides and proteins by electron transfer dissociation.

    Science.gov (United States)

    Rand, Kasper D; Pringle, Steven D; Morris, Michael; Brown, Jeffery M

    2012-02-21

    To interpret the wealth of information contained in the hydrogen/deuterium exchange (HDX) behavior of peptides and proteins in the gas-phase, analytical tools are needed to resolve the HDX of individual exchanging sites. Here we show that ETD can be combined with fast gas-phase HDX in ND(3) gas and used to monitor the exchange of side-chain hydrogens of individual residues in both small peptide ions and larger protein ions a few milliseconds after electrospray. By employing consecutive traveling wave ion guides in a mass spectrometer, peptide and protein ions were labeled on-the-fly (0.1-10 ms) in ND(3) gas and subsequently fragmented by ETD. Fragment ions were separated using ion mobility and mass analysis enabled the determination of the gas-phase deuterium uptake of individual side-chain sites in a range of model peptides of different size and sequence as well as two proteins; cytochrome C and ubiquitin. Gas-phase HDX-ETD experiments on ubiquitin ions ionized from both denaturing and native solution conditions suggest that residue-specific HDX of side-chain hydrogens is sensitive to secondary and tertiary structural features occurring in both near-native and unfolded gas-phase conformers present shortly after electrospray. The described approach for online gas-phase HDX and ETD paves the way for making mass spectrometry techniques based on gas-phase HDX more applicable in bioanalytical research.

  11. Density-driven transport of gas phase chemicals in unsaturated soils.

    Science.gov (United States)

    Fen, Chiu-Shia; Sun, Yong-Tai; Cheng, Yuen; Chen, Yuanchin; Yang, Whaiwan; Pan, Changtai

    2018-01-01

    Variations of gas phase density are responsible for advective and diffusive transports of organic vapors in unsaturated soils. Laboratory experiments were conducted to explore dense gas transport (sulfur hexafluoride, SF 6 ) from different source densities through a nitrogen gas-dry soil column. Gas pressures and SF 6 densities at transient state were measured along the soil column for three transport configurations (horizontal, vertically upward and vertically downward transport). These measurements and others reported in the literature were compared with simulation results obtained from two models based on different diffusion approaches: the dusty gas model (DGM) equations and a Fickian-type molar fraction-based diffusion expression. The results show that the DGM and Fickian-based models predicted similar dense gas density profiles which matched the measured data well for horizontal transport of dense gas at low to high source densities, despite the pressure variations predicted in the soil column were opposite to the measurements. The pressure evolutions predicted by both models were in trend similar to the measured ones for vertical transport of dense gas. However, differences between the dense gas densities predicted by the DGM and Fickian-based models were discernible for vertically upward transport of dense gas even at low source densities, as the DGM-based predictions matched the measured data better than the Fickian results did. For vertically downward transport, the dense gas densities predicted by both models were not greatly different from our experimental measurements, but substantially greater than the observations obtained from the literature, especially at high source densities. Further research will be necessary for exploring factors affecting downward transport of dense gas in soil columns. Use of the measured data to compute flux components of SF 6 showed that the magnitudes of diffusive flux component based on the Fickian-type diffusion

  12. Determination of steroids, caffeine and methylparaben in water using solid phase microextraction-comprehensive two dimensional gas chromatography-time of flight mass spectrometry.

    Science.gov (United States)

    Lima Gomes, Paulo C F; Barnes, Brian B; Santos-Neto, Álvaro J; Lancas, Fernando M; Snow, Nicholas H

    2013-07-19

    Analysis of several emerging contaminants (steroids, caffeine and methylparaben) in water using automated solid-phase microextraction with comprehensive two dimensional gas chromatography coupled to time of flight mass spectrometry (SPME-GCxGC-ToF/MS) is presented. Experimental design was used to determine the best SPME extraction conditions and the steroids were not derivatized prior to injection. SPME-GCxGC-ToF/MS provided linear ranges from 0.6 to 1200μgL(-1) and limits of detection and quantitation from 0.02 to 100μgL(-1). A series of river water samples obtained locally were subjected to analysis. SPME-GCxGC-ToF/MS is readily automated, straightforward and competitive with other methods for low level analysis of emerging contaminants. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Gas phase collision dynamics by means of pulse-radiolysis methods

    International Nuclear Information System (INIS)

    Hatano, Yoshihiko

    1989-01-01

    After a brief survey of recent advances in gas-phase collision dynamics studies using pulse radiolysis methods, the following two topics in our research programs are presented with emphasis on the superior advantages of the pulse radiolysis methods over the various methods of gas-phase collision dynamics, such as beam methods, swarm methods and flow methods. One of the topics is electron attachment to van der Waals molecules. The attachment rates of thermal electrons to O 2 and other molecules in dense gases have been measured in wide ranges of both gas temperatures and pressures, from which experimental evidence has been obtained for electron attachment to van der Waals molecules. The results have been compared with theories and discussed in terms of the effect of van der Waals interaction on the electron attachment resonance. The obtained conclusions have been related with investigations of electron attachment, solvation and localization in the condensed phase. The other is Penning ionization and its related processes. The rate constants for the de-excitation of He(2 1 P), He(2 3 S), Ne( 3 P 0 ), Ne( 3 P 1 ), Ne( 3 P 2 ), Ar( 1 P 1 ), Ar( 3 P 1 ), by atoms and molecules have been measured in the temperature range from 100 to 300 K, thus obtaining the collisional energy dependence of the de-excitation cross sections. The results are compared in detail with theories classified according to the excited rare gas atoms in the metastable and resonance states. (author)

  14. Gas-phase advanced oxidation as an integrated air pollution control technique

    Directory of Open Access Journals (Sweden)

    Getachew A. Adnew

    2016-03-01

    Full Text Available Gas-phase advanced oxidation (GPAO is an emerging air cleaning technology based on the natural self-cleaning processes that occur in the Earth’s atmosphere. The technology uses ozone, UV-C lamps and water vapor to generate gas-phase hydroxyl radicals that initiate oxidation of a wide range of pollutants. In this study four types of GPAO systems are presented: a laboratory scale prototype, a shipping container prototype, a modular prototype, and commercial scale GPAO installations. The GPAO systems treat volatile organic compounds, reduced sulfur compounds, amines, ozone, nitrogen oxides, particles and odor. While the method covers a wide range of pollutants, effective treatment becomes difficult when temperature is outside the range of 0 to 80 °C, for anoxic gas streams and for pollution loads exceeding ca. 1000 ppm. Air residence time in the system and the rate of reaction of a given pollutant with hydroxyl radicals determine the removal efficiency of GPAO. For gas phase compounds and odors including VOCs (e.g. C6H6 and C3H8 and reduced sulfur compounds (e.g. H2S and CH3SH, removal efficiencies exceed 80%. The method is energy efficient relative to many established technologies and is applicable to pollutants emitted from diverse sources including food processing, foundries, water treatment, biofuel generation, and petrochemical industries.

  15. Gas-phase removal of biofilms from various surfaces using carbon dioxide aerosols.

    Science.gov (United States)

    Cha, Minju; Hong, Seongkyeol; Kang, Min-Yeong; Lee, Jin-Won; Jang, Jaesung

    2012-01-01

    The present study evaluated the removal of Escherichia coli XL1-blue biofilms using periodic jets of carbon dioxide aerosols (a mixture of solid and gaseous CO(2)) with nitrogen gas. The aerosols were generated by the adiabatic expansion of high-pressure CO(2) gas through a nozzle and used to remove air-dried biofilms. The areas of the biofilms were measured from scanning electron micrographs before and after applying the aerosols. The removal efficiency of the aerosol treatment was measured with various air-drying times of the biofilms before the treatment, surface materials, and durations of CO(2) aerosols in each 8-s aerosol-nitrogen cleaning cycle. Nearly 100% of the fresh biofilms were removed from the various surfaces very reliably within 90 s. This technique can be useful for removing unsaturated biofilms on solid surfaces and has potential applications for cleaning bio-contaminated surfaces.

  16. Laboratory Measurements of Gas Phase Pyrolysis Products from Southern Wildland Fuels using Infrared Spectroscopy

    Science.gov (United States)

    Scharko, N.; Safdari, S.; Danby, T. O.; Howarth, J.; Beiswenger, T. N.; Weise, D.; Myers, T. L.; Fletcher, T. H.; Johnson, T. J.

    2017-12-01

    Combustion is an oxidation reaction that occurs when there is less fuel available than oxidizers, while pyrolysis is a thermal decomposition process that occurs under "fuel rich" conditions where all of the available oxidizers are consumed leaving some fuel(s) either unreacted or partially reacted. Gas-phase combustion products from biomass burning experiments have been studied extensively; less is known, however, about pyrolysis processes and products. Pyrolysis is the initial reaction occurring in the burning process and generates products that are subsequently oxidized during combustion, yielding highly-oxidized chemicals. This laboratory study investigates the pyrolysis processes by using an FTIR spectrometer to detect and quantify the gas-phase products from thermal decomposition of intact understory fuels from forests in the southeastern United States. In particular, a laboratory flat-flame burner operating under fuel rich conditions (no oxygen) was used to heat individual leaves to cause decomposition. The gas-phase products were introduced to an 8 meter gas cell coupled to an infrared spectrometer were used to monitor the products. Trace gas emissions along with emission ratios, which are calculated by dividing the change in the amount of the trace gas by the change in the amount of CO, for the plant species, gallberry (Ilex glabra) and swampbay (Persea palustris) were determined. Preliminary measurements observed species such as CO2, CO, C2H2, C2H4, HCHO, CH3OH, isoprene, 1,3-butadiene, phenol and NH3 being produced as part of the thermal decomposition process. It is important to note that FTIR will not detect H2.

  17. Experiments and Phase-field Modeling of Hydrate Growth at the Interface of Migrating Gas Fingers

    Science.gov (United States)

    Fu, X.; Jimenez-Martinez, J.; Porter, M. L.; Cueto-Felgueroso, L.; Juanes, R.

    2016-12-01

    The fate of methane bubbles escaping from seafloor seeps remains an important research question, as it directly concerns our understanding of the impact of seafloor methane leakage on ocean biogeochemistry. While the physics of rising bubbles in a water column has been studied extensively, the process is poorly understood when the gas bubbles form a hydrate ``crust" during their ascent. Understanding bubble rise, expansion and dissolution under these conditions is essential to determine the fate of bubble plumes of hydrate-forming gases such as methane and carbon dioxide from natural and man-made accidental releases. Here, we first present experimental observations of the dynamics of a bubble of Xenon in a water-filled and pressurized Hele-Shaw cell. The evolution is controlled by two processes: (1) the formation of a hydrate "crust" around the bubble, and (2) viscous fingering from bubble expansion (Figure 1). To reproduce the experimental observations, we propose a phase-field model that describes the nucleation and thickening of a porous solid shell on a moving gas-liquid interface. We design the free energy of the three-phase system (gas-liquid-hydrate) to rigorously account for interfacial effects, mutual solubility, and phase transformations (hydrate formation and disappearance). We introduce a pseudo-plasticity model with large viscosity variations to describe the plate-like rheology of the hydrate shell. We present high-resolution numerical simulations of the model, which illustrate the emergence of complex "crustal fingering" patterns as a result of gas fingering dynamics modulated by hydrate growth at the interface. Figure caption: Snapshot of the Hele-Shaw cell experiment. As the bubble expands from depressurization of the cell, gas fingers move through the liquid and Xe-hydrate readily forms at the gas-liquid interface, giving rise to complex "crustal fingering" patterns.

  18. Liquid-gas phase transition in strange hadronic matter with relativistic models

    Science.gov (United States)

    Torres, James R.; Gulminelli, F.; Menezes, Débora P.

    2016-02-01

    Background: The advent of new dedicated experimental programs on hyperon physics is rapidly boosting the field, and the possibility of synthesizing multiple strange hypernuclei requires the addition of the strangeness degree of freedom to the models dedicated to nuclear structure and nuclear matter studies at low energy. Purpose: We want to settle the influence of strangeness on the nuclear liquid-gas phase transition. Because of the large uncertainties concerning the hyperon sector, we do not aim at a quantitative estimation of the phase diagram but rather at a qualitative description of the phenomenology, as model independent as possible. Method: We analyze the phase diagram of low-density matter composed of neutrons, protons, and Λ hyperons using a relativistic mean field (RMF) model. We largely explore the parameter space to pin down generic features of the phase transition, and compare the results to ab initio quantum Monte Carlo calculations. Results: We show that the liquid-gas phase transition is only slightly quenched by the addition of hyperons. Strangeness is seen to be an order parameter of the phase transition, meaning that dilute strange matter is expected to be unstable with respect to the formation of hyperclusters. Conclusions: More quantitative results within the RMF model need improved functionals at low density, possibly fitted to ab initio calculations of nuclear and Λ matter.

  19. Comprehensive Gas-Phase Peptide Ion Structure Studies Using Ion Mobility Techniques: Part 2. Gas-Phase Hydrogen/Deuterium Exchange for Ion Population Estimation

    Science.gov (United States)

    Khakinejad, Mahdiar; Ghassabi Kondalaji, Samaneh; Tafreshian, Amirmahdi; Valentine, Stephen J.

    2017-05-01

    Gas-phase hydrogen/deuterium exchange (HDX) using D2O reagent and collision cross-section (CCS) measurements are utilized to monitor the ion conformers of the model peptide acetyl-PAAAAKAAAAKAAAAKAAAAK. The measurements are carried out on a home-built ion mobility instrument coupled to a linear ion trap mass spectrometer containing electron transfer dissociation (ETD) capabilities. ETD is utilized to obtain per-residue deuterium uptake data for select ion conformers, and a new algorithm is presented for interpreting the HDX data. Using molecular dynamics (MD) production data and a hydrogen accessibility scoring (HAS)-number of effective collisions (NEC) model, hypothetical HDX behavior is attributed to various in-silico candidate (CCS match) structures. The HAS-NEC model is applied to all candidate structures, and non-negative linear regression is employed to determine structure contributions resulting in the best match to deuterium uptake. The accuracy of the HAS-NEC model is tested with the comparison of predicted and experimental isotopic envelopes for several of the observed c-ions. It is proposed that gas-phase HDX can be utilized effectively as a second criterion (after CCS matching) for filtering suitable MD candidate structures. In this study, the second step of structure elucidation, 13 nominal structures were selected (from a pool of 300 candidate structures) and each with a population contribution proposed for these ions.

  20. Determination of petroleum fractions as contaminants in the waters by gas chromatography

    International Nuclear Information System (INIS)

    Kubinec, R.; Mracnova, R.; Kuran, P.; Ostrovsky, I.; Sojak, L.

    1995-01-01

    The method of micro-extraction of petroleum fractions from water and analysis using gas chromatography was developed. This method can be used for the analysis of gaseous oil and mineral oil in the water wit the detection limit 12 ppb and 18 ppb, respectively

  1. Toxicity of sediments potentially contaminated by coal mining and natural gas extraction to unionid mussels and commonly tested benthic invertebrates

    Science.gov (United States)

    Wang, Ning; Ingersoll, Christopher G.; Kunz, James L.; Brumbaugh, William G.; Kane, Cindy M.; Evans, R. Brian; Alexander, Steven; Walker, Craig; Bakaletz, Steve

    2013-01-01

    Sediment toxicity tests were conducted to assess potential effects of contaminants associated with coal mining or natural gas extraction activities in the upper Tennessee River basin and eastern Cumberland River basin in the United States. Test species included two unionid mussels (rainbow mussel, Villosa iris, and wavy-rayed lampmussel, Lampsilis fasciola, 28-d exposures), and the commonly tested amphipod, Hyalella azteca (28-d exposure) and midge, Chironomus dilutus (10-d exposure). Sediments were collected from seven test sites with mussel communities classified as impacted and in proximity to coal mining or gas extraction activities, and from five reference sites with mussel communities classified as not impacted and no or limited coal mining or gas extraction activities. Additional samples were collected from six test sites potentially with high concentrations of polycyclic aromatic hydrocarbons (PAHs) and from a test site contaminated by a coal ash spill. Mean survival, length, or biomass of one or more test species was reduced in 10 of 14 test samples (71%) from impacted areas relative to the response of organisms in the five reference samples. A higher proportion of samples was classified as toxic to mussels (63% for rainbow mussels, 50% for wavy-rayed lampmussels) compared with amphipods (38%) or midge (38%). Concentrations of total recoverable metals and total PAHs in sediments did not exceed effects-based probable effect concentrations (PECs). However, the survival, length, or biomasses of the mussels were reduced significantly with increasing PEC quotients for metals and for total PAHs, or with increasing sum equilibrium-partitioning sediment benchmark toxic units for PAHs. The growth of the rainbow mussel also significantly decreased with increasing concentrations of a major anion (chloride) and major cations (calcium and magnesium) in sediment pore water. Results of the present study indicated that (1) the findings from laboratory tests were generally

  2. Gas-Phase Oxidation of Aqueous Ethanol by Nanoparticle Vanadia/Anatase Catalysts

    DEFF Research Database (Denmark)

    Jørgensen, Betina; Kristensen, Steffen Buus; Kunov-Kruse, Andreas Jonas

    2009-01-01

    The gas-phase oxidation of aqueous ethanol with dioxygen has been examined with a new nanoparticle V2O5/TiO2 catalyst. Product selectivity could to a large extent be controlled by small alterations of reaction parameters, allowing production of acetaldehyde at a selectivity higher than 90%, near...... quantitative conversion at 175-200 A degrees C. Furthermore, a selectivity above 80% for acetic acid could be achieved at low gas hourly space velocity at temperatures as low as 165 A degrees C....

  3. Review: gas-phase ion chemistry of the noble gases: recent advances and future perspectives.

    Science.gov (United States)

    Grandinetti, Felice

    2011-01-01

    This review article surveys recent experimental and theoretical advances in the gas-phase ion chemistry of the noble gases. Covered issues include the interaction of the noble gases with metal and non-metal cations, the conceivable existence of covalent noble-gas anions, the occurrence of ion-molecule reactions involving singly-charged xenon cations, and the occurrence of bond-forming reactions involving doubly-charged cations. Research themes are also highlighted, that are expected to attract further interest in the future.

  4. Phase diagrams for an ideal gas mixture of fermionic atoms and bosonic molecules

    DEFF Research Database (Denmark)

    Williams, J. E.; Nygaard, Nicolai; Clark, C. W.

    2004-01-01

    We calculate the phase diagrams for a harmonically trapped ideal gas mixture of fermionic atoms and bosonic molecules in chemical and thermal equilibrium, where the internal energy of the molecules can be adjusted relative to that of the atoms by use of a tunable Feshbach resonance. We plot...... diagrams obtained in recent experiments on the Bose-Einstein condensation to Bardeen-Cooper-Schrieffer crossover, in which the condensate fraction is plotted as a function of the initial temperature of the Fermi gas measured before a sweep of the magnetic field through the resonance region....

  5. Two-Phase Gas-Liquid Flow Structure Characteristics under Periodic Cross Forces Action

    Directory of Open Access Journals (Sweden)

    V. V. Perevezentsev

    2015-01-01

    Full Text Available The article presents a study of two-phase gas-liquid flow under the action of periodic cross forces. The work objective is to obtain experimental data for further analysis and have structure characteristics of the two-phase flow movement. For research, to obtain data without disturbing effect on the flow were used optic PIV (Particle Image Visualization methods because of their noninvasiveness. The cross forces influence was provided by an experimental stand design to change the angular amplitudes and the periods of channel movement cycle with two-phase flow. In the range of volume gas rates was shown a water flow rate versus the inclination angle of immovable riser section and the characteristic angular amplitudes and periods of riser section inclination cycle under periodic cross forces. Data on distribution of average water velocity in twophase flow in abovementioned cases were also obtained. These data allowed us to draw a conclusion that a velocity distribution depends on the angular amplitude and on the period of the riser section roll cycle. This article belongs to publications, which study two-phase flows with no disturbing effect on them. Obtained data give an insight into understanding a pattern of twophase gas-liquid flow under the action of periodic cross forces and can be used to verify the mathematical models of the CFD thermo-hydraulic codes. In the future, the work development expects taking measurements with more frequent interval in the ranges of angular amplitudes and periods of the channel movement cycle and create a mathematical model to show the action of periodic cross forces on two-phase gas-liquid flow.

  6. Beyond phthalates: Gas phase concentrations and modeled gas/particle distribution of modern plasticizers

    Energy Technology Data Exchange (ETDEWEB)

    Schossler, Patricia [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Institute of Environmental and Sustainable Chemistry, Technische Universitaet Braunschweig, Hagenring 30, D-38106 Braunschweig (Germany); Schripp, Tobias, E-mail: tobias.schripp@wki.fraunhofer.de [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Salthammer, Tunga [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Bahadir, Muefit [Institute of Environmental and Sustainable Chemistry, Technische Universitaet Braunschweig, Hagenring 30, D-38106 Braunschweig (Germany)

    2011-09-01

    The ongoing health debate about polymer plasticizers based on the esters of phthalic acid, especially di(2-ethylhexyl) phthalate (DEHP), has caused a trend towards using phthalates of lower volatility such as diisononyl phthalate (DINP) and towards other acid esters, such as adipates, terephthalates, citrates, etc. Probably the most important of these so-called 'alternative' plasticizers is diisononyl cyclohexane-1,2-dicarboxylate (DINCH). In the indoor environment, the continuously growing market share of this compound since its launch in 2002 is inter alia apparent from the increasing concentration of DINCH in settled house dust. From the epidemiological point of view there is considerable interest in identifying how semi-volatile organic compounds (SVOCs) distribute in the indoor environment, especially in air, airborne particles and sedimented house dust. This, however, requires reliable experimental concentration data for the different media and good measurements or estimates of their physical and chemical properties. This paper reports on air concentrations for DINP, DINCH, diisobutyl phthalate (DIBP), diisobutyl adipate (DIBA), diisobutyl succinate (DIBS) and diisobutyl glutarate (DIBG) from emission studies in the Field and Laboratory Emission Cell (FLEC). For DINP and DINCH it took about 50 days to reach the steady-state value: for four months no decay in the concentration could be observed. Moreover, vapor pressures p{sub 0} and octanol-air partitioning coefficients K{sub OA} were obtained for 37 phthalate and non-phthalate plasticizers from two different algorithms: EPI Suite and SPARC. It is shown that calculated gas/particle partition coefficients K{sub p} and fractions can widely differ due to the uncertainty in the predicted p{sub 0} and K{sub OA} values. For most of the investigated compounds reliable experimental vapor pressures are not available. Rough estimates can be obtained from the measured emission rate of the pure compound in a

  7. Novel gas holdup and regime transition correlation for two-phase bubble columns

    Science.gov (United States)

    Besagni, G.; Inzoli, F.

    2017-11-01

    The gas holdup is dimensionless parameter of fundamental and practical importance in the operation, design and scale-up of bubble columns. Unfortunately, the many relationships between the bubble column fluid dynamic parameters and the various variables characterizing the system make it difficult to find general correlations for the precise estimation of the gas holdup. Wilkinson et al. (1992), in their pioneering paper, proposed a correlation to predict the gas holdup in industrial-scale bubble columns, based on the physical properties of the phases and the operating conditions. However, this correlation lacks in generality, as it does not take in account the bubble column design. In this paper, we propose a generalization of the Wilkinson et al. (1992) gas holdup correlation to take into also the bubble column design parameters. Starting from considerations concerning the flow regime transition, corrective parameters are included to account for the effects introduced by the gas sparger openings, the bubble column aspect ratio and the bubble column diameter. The proposed correlation has been found to predict fairly well previously published gas holdup and flow regime transition data.

  8. CFD simulation of gas and non-Newtonian fluid two-phase flow in anaerobic digesters.

    Science.gov (United States)

    Wu, Binxin

    2010-07-01

    This paper presents an Eulerian multiphase flow model that characterizes gas mixing in anaerobic digesters. In the model development, liquid manure is assumed to be water or a non-Newtonian fluid that is dependent on total solids (TS) concentration. To establish the appropriate models for different TS levels, twelve turbulence models are evaluated by comparing the frictional pressure drops of gas and non-Newtonian fluid two-phase flow in a horizontal pipe obtained from computational fluid dynamics (CFD) with those from a correlation analysis. The commercial CFD software, Fluent12.0, is employed to simulate the multiphase flow in the digesters. The simulation results in a small-sized digester are validated against the experimental data from literature. Comparison of two gas mixing designs in a medium-sized digester demonstrates that mixing intensity is insensitive to the TS in confined gas mixing, whereas there are significant decreases with increases of TS in unconfined gas mixing. Moreover, comparison of three mixing methods indicates that gas mixing is more efficient than mixing by pumped circulation while it is less efficient than mechanical mixing.

  9. Fractionation of Hydrocarbons Between Oil and Gas Phases Fractionnement des hydrocarbures entre les phases huile et gaz

    Directory of Open Access Journals (Sweden)

    Ruffier-Meray V.

    2006-12-01

    Full Text Available The investigation of hydrocarbon fractionation between oil and gas phases is of interest for several purposes in reservoir exploitation. In reservoir geochemistry, the evolution of light hydrocarbon fractions of oils may explain some migration phenomena. In gas injection projects, the preferred dissolution of some components in gas may alter the composition as well as the properties of the oil. Underground gas storage in depleted oil reservoirs may also be concerned by these problems. Results of several IFP studies are described here to illustrate and to quantify the phenomenon. Two of them, using real reservoir fluids, concern reservoir geochemistry, while the third, which is a swelling test, aimed to study gas injection, investigated a synthetic reservoir fluid with hydrocarbon components up to C30. Two pieces of equipment were used: a sapphire cell with a maximum pressure rating of 400 bar and a high pressure apparatus called Hercule with a maximum pressure of 1500 bar. For each fluid, the saturation pressure was measured. For various pressure levels below saturation, the coexisting liquid and gas phases were sampled at constant pressure, and subsequently analyzed by gas chromatography. In the gas injection study, sampling was repeated with different quantities of injection gas. Compared to a n-paraffin with the same number of carbon atoms, aromatic hydrocarbons appear to stay preferentially in the liquid phase, as do cycloalkanes to a lesser extent. The gaseous phase is slightly enriched in isoalkanes. These fractionation effects are less pronounced near the critical region. These phenomena have been modeled with a cubic equation of state combined with a group contribution mixing rule. L'étude du fractionnement des hydrocarbures légers entre les phases gazeuses et liquides intéresse plusieurs domaines dans le cadre de l'exploitation des gisements. En géochimie de réservoir l'évolution de la composition de la fraction légère peut

  10. Push-pull partitioning tracer tests using radon-222 to quantify non-aqueous phase liquid contamination.

    Science.gov (United States)

    Davis, B M; Istok, J D; Semprini, L

    2002-09-01

    Naturally occurring radon in groundwater can be used as an in situ partitioning tracer for locating and quantifying non-aqueous phase liquid (NAPL) contamination in the subsurface. When combined with the single-well, push-pull test, this methodology has the potential to provide a low-cost alternative to inter-well partitioning tracer tests. During a push-pull test, a known volume of test solution (radon-free water containing a conservative tracer) is first injected ("pushed") into a well; flow is then reversed and the test solution/groundwater mixture is extracted ("pulled") from the same well. In the presence of NAPL radon transport is retarded relative to the conservative tracer. Assuming linear equilibrium partitioning, retardation factors for radon can be used to estimate NAPL saturations. The utility of this methodology was evaluated in laboratory and field settings. Laboratory push-pull tests were conducted in both non-contaminated and trichloroethene NAPL (TCE)-contaminated sediment. The methodology was then applied in wells located in non-contaminated and light non-aqueous phase liquid (LNAPL)-contaminated portions of an aquifer at a former petroleum refinery. The method of temporal moments and an approximate analytical solution to the governing transport equations were used to interpret breakthrough curves and estimate radon retardation factors; estimated retardation factors were then used to calculate TCE saturations. Numerical simulations were used to further investigate the behavior of the breakthrough curves. The laboratory and field push-pull tests demonstrated that radon retardation does occur in the presence of TCE and LNAPL and that radon retardation can be used to calculate TCE saturations. Laboratory injection-phase test results in TCE-contaminated sediment yielded radon retardation factors ranging from 1.1 to 1.5, resulting in calculated TCE saturations ranging from 0.2 to 0.9%. Laboratory extraction-phase test results in the same sediment

  11. Evaluation of gamma radiation effects on stationary phases using gas chromatografy

    International Nuclear Information System (INIS)

    Basso, M.A.; Collins, K.E.; Collins, C.H.

    1988-01-01

    The overall objetive of this project is a thorough study of the effect of gamma radiation on supported stationary phases used in packed-column gas chromatography. The phases studied were SP-2100 on Supelcoport and SE-30 on Chromsorb W. The fases were irradiated with cobalt-60 gamma rays to various doses and subsequently subjected to tests of extractability, termal stability and efficiency as a chromatographic column packing. Extraction tests indicate that low doses of radiation are sufficient to produce significant immobilization of these polymethylsilicones; that is, to produce chemical bonds between different polymer chains or between the stationary phase and the support. Thermal stability is also increased. The values calculated for the number of theoretical plates (n) and resolution (Rsub (s)) after analysis of four synthetic mixtures of organic compounds also increase, in most cases, indicating that the gamma irradiation has positively altered the behavior of these stationary phases. (author) [pt

  12. Radioactive contamination monitoring device for off-gas in ventilation system

    International Nuclear Information System (INIS)

    Osaki, Masahiko; Watabe, Atsushi; Kaneko, Itaru; Kubokoya, Takashi.

    1990-01-01

    In a conventional method of detecting leakage for primary coolants, radioactive iodine in off-gases was detected while going up the off-gas system. As an event resulting in abnormality to radioactive rare gas level, leakage of water, leakage in cleanup system-recycling system, leakage in main steams and leakage from wastes processing system are considered. An off-gas system to be measured is selectively sampled by a sample changer in order to measure radioactive rare gases in the off-gases, and sample gases are introduced to detect radioactivity. Detection signals are received for analysis and quantitative determination, the result of the analysis is diagnosed and the presence or absence of abnormality in an object to be measured is determined. Subsequently, an abnormality alarm and the result of the analysis are outputted. Since the radioactive rare gases are chemically inactive, they are neither combined with other materials nor deposited to wall surfaces. Abnormality can be easily detected by always monitoring a composition pattern and a radioactivity level. (N.H.)

  13. Looking for diagnostics parameters of bearings of the gas turbine engine LM 2500 on the basis of mechanical contaminations in the lubricating oil

    Directory of Open Access Journals (Sweden)

    Waldemar MIRONIUK

    2009-01-01

    Full Text Available While operation a gas turbine engine more modest methods of research are brought into effect. But one of the basic methods to estimate the technical condition of gas turbine engines bearing is oil analysis. To estimate the technical condition of gas turbine engines bearing systems on the basis of oil research on, an x-ray method of radio-isotope fluorescence was used. This method has been also satisfactorily used in aircraft engine diagnosis.This paper presents the method of diagnosis bearings of marine gas turbines on the basis of studies of mechanical contamination in oil. Results of mechanical contamination research in oil vs time of engine work are presented. On the basis of experiments results the analytical function that makes calculating the future value of the process possible was chosen.

  14. MOLECULAR SPECTROSCPY AND REACTIONS OF ACTINIDES IN THE GAS PHASE AND CRYOGENIC MATRICES

    Energy Technology Data Exchange (ETDEWEB)

    Heaven, Michael C.; Gibson, John K.; Marcalo, Joaquim

    2009-02-01

    In this chapter we review the spectroscopic data for actinide molecules and the reaction dynamics for atomic and molecular actinides that have been examined in the gas phase or in inert cryogenic matrices. The motivation for this type of investigation is that physical properties and reactions can be studied in the absence of external perturbations (gas phase) or under minimally perturbing conditions (cryogenic matrices). This information can be compared directly with the results from high-level theoretical models. The interplay between experiment and theory is critically important for advancing our understanding of actinide chemistry. For example, elucidation of the role of the 5f electrons in bonding and reactivity can only be achieved through the application of experimentally verified theoretical models. Theoretical calculations for the actinides are challenging due the large numbers of electrons that must be treated explicitly and the presence of strong relativistic effects. This topic has been reviewed in depth in Chapter 17 of this series. One of the goals of the experimental work described in this chapter has been to provide benchmark data that can be used to evaluate both empirical and ab initio theoretical models. While gas-phase data are the most suitable for comparison with theoretical calculations, there are technical difficulties entailed in generating workable densities of gas-phase actinide molecules that have limited the range of species that have been characterized. Many of the compounds of interest are refractory, and problems associated with the use of high temperature vapors have complicated measurements of spectra, ionization energies, and reactions. One approach that has proved to be especially valuable in overcoming this difficulty has been the use of pulsed laser ablation to generate plumes of vapor from refractory actinide-containing materials. The vapor is entrained in an inert gas, which can be used to cool the actinide species to room

  15. Chlorination of some eliphatic organic compounds in liquid and gas phase

    International Nuclear Information System (INIS)

    Hassan, A.A.

    1990-01-01

    The photochlorination of different organic compounds and the relative slectivities of different positions have been investigated in both gaseous and liquid phases at different temperatures. The results have shown that the relative selectivity generally decreased with increasing temperature and in the gas phase has a higher value. Polar solvents increase the selectivity relative to the chlorination of pure liquid phases. The differences in activation energy between two positions were much higher in the gas phases chlorination, relative to that in the liquid phase. It was also found that the functional groups have great influence on the rate of chlorine free radical attack on different positions, for example the electron withdrawing groups decreasing the selectivity on the first position, but the electron donating groups increase the selectivity on the first position, but the electron donating groups increase the selectivity on the first position. Furthermore it was found that the polar solvents, which stabilize the resonance between oxygen and carbon atoms, increases the selectivity on that position. 23 tabs.; 16 figs.; 50 refs

  16. Crosslinkable mixed matrix membranes with surface modified molecular sieves for natural gas purification: II. Performance characterization under contaminated feed conditions

    KAUST Repository

    Ward, Jason K.

    2011-07-01

    Mixed matrix membranes (MMMs) composed of the crosslinkable polyimide PDMC and surface modified (SM) SSZ-13 have recently been shown to enhance carbon dioxide permeability and carbon dioxide/methane selectivity versus neat PDMC films by as much as 47% and 13%, respectively (Part I). The previous film characterization, however, was performed using ideal, clean mixed gas feeds. In this paper, PDMC/SSZ-13 MMMs are further characterized using more realistic mixed gases containing low concentrations (500 or 1000. ppm) of toluene as a model contaminant. Mixed matrix membranes are shown to outperform pure PDMC films in the presence of toluene with 43% greater carbon dioxide permeability and 12% greater carbon dioxide/selectivity at 35 °C and 700 psia feed pressure. These results suggest that MMMs-in addition to exhibiting enhanced transport properties-may mitigate performance degradation due to antiplasticization effects. Moreover, the analyses presented here show that the reduction in separation performance by trace contaminant-accelerated physical aging can be suppressed greatly with MMMs. © 2011 Elsevier B.V.

  17. A Nanoparticulate Photocatalytic Filter for Removal of Trace Contaminant Gases, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Maintaining a healthy atmosphere in closed life support systems is necessary for the well being of the crew and success of a space mission. Current trace contaminant...

  18. Novel, Vacuum-Regenerable Trace Contaminant Control System for Advanced Spacesuit Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Trace contaminants that are introduced into the ventilation loop of a spacesuit (primarily ammonia and formaldehyde) via metabolic processes, off-gassing of...

  19. Polymer Coating-Based Contaminant Control/Elimination for Exo-S Starshade Probe, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Our past success in developing what has proven to be a revolution in contamination control – that of residue free, strippable polymer coatings for surface protection...

  20. Novel, Vacuum-Regenerable Trace Contaminant Control System for Advanced Spacesuit Applications, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Precision Combustion, Inc. (PCI) proposes a new material paradigm for the Trace Contaminant Control System (TCCS) based upon its novel adsorbent nanomaterials that...

  1. A Nanoparticulate Photocatalytic Filter for Removal of Trace Contaminant Gases, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Maintaining a healthy atmosphere in closed life support systems is essential for crew well being and success of space missions. Current trace contaminant control...

  2. Fluorometric method for the determination of gas-phase hydrogen peroxide

    Science.gov (United States)

    Kok, Gregory L.; Lazrus, Allan L.

    1986-01-01

    The fluorometric gas-phase hydrogen peroxide procedure is based on the technique used by Lazrus et. al. for the determination of H2O2 in the liquid phase. The analytical method utilizes the reaction of H2O2 with horseradish peroxidase and p-hydroxphenylacetic acid (POPHA) to form the fluorescent dimer of POPHA. The analytical reaction responds stoichiometrically to both H2O2 and some organic hydroperoxides. To discriminate H2O2 from organic hydroperoxides, catalase is used to preferentially destroy H2O2. Using a dual-channel flow system the H2O2 concentration is determined by difference.

  3. Optimization of phase analysis of refractory alloys in the gas-ion-reaction chamber

    International Nuclear Information System (INIS)

    Blumenkamp, H.J.; Hoven, H.; Koizlik, K.; Nickel, H.

    1980-04-01

    Reactor components outside the core which are under high thermal and mechanical stresses are made from refractory alloys. For basic research and for quality control, these materials are investigated by metallography, which is an independent group of characterization procedures as well as basis for many other methods. An important way of increasing the information about a material yielded by metallography is the expansions of phase contrast, in particular the phase contrasting in the gas-ion-reaction chamber. In this paper, the experimental procedure is described and the process of optimizing the procedure with respect to the Ni- and Fe-based refractory alloys examined in the IRW is discussed. (orig.) [de

  4. Measurement of gas phase characteristics using new monofiber optical probes and real time signal processing

    International Nuclear Information System (INIS)

    Cartellier, A.

    1998-01-01

    Single optical or impedance phase detection probes are able to measure gas velocities provided that their sensitive length L is accurately known. In this paper, it is shown that L can be controlled during the manufacture of optical probes. Beside, for a probe geometry in the form of a cone + a cylinder + a cone, the corresponding rise time / velocity correlation becomes weakly sensitive to uncontrollable parameter such as the angle of impact on the interface. A real time signal processing performing phase detection as well as velocity measurements is described. Since its sensitivity to the operator inputs is less than the reproducibility of measurements, it is a fairly objective tool. Qualifications achieved in air/water flows with various optical probes demonstrate that the void fraction is detected with a relative error less than 10 %. For bubbly flows, the gas flux is accurate within ±10%, but this uncertainty increases when large bubbles are present in the flow. (author)

  5. Methods and apparatus for using gas and liquid phase cathodic depolarizers

    Science.gov (United States)

    Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor)

    1998-01-01

    The invention provides methods for using gas and liquid phase cathodic depolarizers in an electrochemical cell having a cation exchange membrane in intimate contact with the anode and cathode. The electrochemical conversion of cathodic depolarizers at the cathode lowers the cell potential necessary to achieve a desired electrochemical conversion, such as ozone evolution, at the anode. When gaseous cathodic depolarizers, such as oxygen, are used, a gas diffusion cathode having the cation exchange membrane bonded thereto is preferred. When liquid phase cathodic depolarizers are used, the cathode may be a flow-by electrode, flow-through electrode, packed-bed electrode or a fluidized-bed electrode in intimate contact with the cation exchange membrane.

  6. ICR studies of some anionic gas phase reactions and FTICR software design

    International Nuclear Information System (INIS)

    Noest, A.J.

    1983-01-01

    This thesis consists of two parts. Part one (Chs. 1-5) reports experimental results from mostly drift-cell ICR studies of negative ion-molecule reactions; part two (Chs. 6-11) concerns the design of software for an FTICR instrument. The author discusses successively: 1. ion cyclotron resonance spectrometry; 2. the gas phase allyl anion; 3. the (M-H) and (M-H2) anions from acetone; 4. negative ion-molecule reactions of aliphatic nitrites studied by cyclotron resonance; 5. homoconjugation versus charge-dipole interaction effects in the stabilization of carbanions in the gas phase; 6. the Fourier Transform ICR method; 7. the FTICR-software; 8. an efficient adaptive matcher filter for fast transient signals; 9. reduction of spectral peak height errors by time-domain weighing; 10. Chirp excitation; 11. Compact data storage. The book concludes with a Dutch and English summary (G.J.P.)

  7. UV-Vis absorption spectra and electronic structure of merocyanines in the gas phase

    Science.gov (United States)

    Ishchenko, Alexander A.; Kulinich, Andrii V.; Bondarev, Stanislav L.; Raichenok, Tamara F.

    2018-02-01

    Gas-phase absorption spectra of a merocyanine vinylogous series have been studied for the first time. In vapour, their long-wavelength absorption bands were found to be considerably shifted hypsochromically, broader, more symmetrical, less intense, and their vinylene shift much smaller than even in low-polarity n-hexane. This indicates that in the gas phase their electronic structure closely approaches the nonpolar polyene limiting structure. The TDDFT calculations of the long-wavelength electronic transitions in the studied merocyanines in vacuo demonstrated good-to-excellent correlation - depending on the functional used - with the obtained experimental data. For comparison, the solvent effects was accounted for using the polarizable continuum model (PCM) with n-hexane and ethanol as low-polarity and high-polarity media, and compared with the UV-Vis spectral data in these solvents. In this case, the discrepancy between theory and experiment was much greater, increasing at that with the polymethine chain length.

  8. Ultraslow isomerization in photoexcited gas-phase carbon cluster [Formula: see text].

    Science.gov (United States)

    Saha, K; Chandrasekaran, V; Heber, O; Iron, M A; Rappaport, M L; Zajfman, D

    2018-03-02

    Isomerization and carbon chemistry in the gas phase are key processes in many scientific studies. Here we report on the isomerization process from linear [Formula: see text] to its monocyclic isomer. [Formula: see text] ions were trapped in an electrostatic ion beam trap and then excited with a laser pulse of precise energy. The neutral products formed upon photoexcitation were measured as a function of time after the laser pulse. It was found using a statistical model that, although the system is excited above its isomerization barrier energy, the actual isomerization from linear to monocyclic conformation takes place on a very long time scale of up to hundreds of microseconds. This finding may indicate a general phenomenon that can affect the interstellar medium chemistry of large molecule formation as well as other gas phase processes.

  9. Theoretical investigation of the long-lived metastable AlO2+ dication in gas phase

    International Nuclear Information System (INIS)

    Sghaier, Onsi; Abdallah, Hassan H.; Abdullah, Hewa Y.; Jaidane, Nejm Eddine; Al Mogren, Muneerah Mogren; Hochlaf, Majdi

    2016-01-01

    Highlights: • Theoretical investigation of gas-phase molecular species AlO 2+ . • Spectroscopic parameters of this dication in its electronic ground and exited states. • Theoretical double ionization spectrum of AlO. - Abstract: We report the results of a detailed theoretical study of the electronic ground and excited states of the gas-phase doubly charged ion AlO 2+ using high-level ab initio computer calculations. Both standard and explicitly correlated methods were used to calculate their potential energy curves and spectroscopic parameters. These computations show that the ground state of AlO 2+ is X 2 Π. The internuclear equilibrium distance of AlO 2+ (X 2 Π) is computed 1.725 Å. We also deduced the adiabatic double ionization and charge stripping energies of AlO to be about 27.45 eV and 17.80 eV, respectively.

  10. Mass-independent oxygen isotopic partitioning during gas-phase SiO2 formation.

    Science.gov (United States)

    Chakraborty, Subrata; Yanchulova, Petia; Thiemens, Mark H

    2013-10-25

    Meteorites contain a wide range of oxygen isotopic compositions that are interpreted as heterogeneity in solar nebula. The anomalous oxygen isotopic compositions of refractory mineral phases may reflect a chemical fractionation process in the nebula, but there are no experiments to demonstrate this isotope effect during particle formation through gas-phase reactions. We report experimental results of gas-to-particle conversion during oxidation of silicon monoxide that define a mass-independent line (slope one) in oxygen three-isotope space of (18)O/(16)O versus (17)O/(16)O. This mass-independent chemical reaction is a potentially initiating step in nebular meteorite formation, which would be capable of producing silicate reservoirs with anomalous oxygen isotopic compositions.

  11. Ab initio treatment of gas phase GeO{sup 2+} doubly charged ion

    Energy Technology Data Exchange (ETDEWEB)

    Mogren Al Mogren, M. [Chemistry Department, Faculty of Science, King Saud University, PO Box 2455, Riyadh 11451 (Saudi Arabia); Ben Abdallah, D. [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications – LSAMA, Université de Tunis, Tunis (Tunisia); Department of General Studies, Riyadh Corporation of Technology, Technical and Vocational Training Corporation, PO Box 42826, Riyadh 11551 (Saudi Arabia); Hochlaf, M., E-mail: hochlaf@univ-mlv.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France)

    2015-01-13

    Highlights: • Theoretical investigation of the novel gas-phase molecular species GeO{sup 2+}. • Spectroscopic parameters of this dication in its electronic ground and exited states. • Theoretical double ionization spectrum of GeO. - Abstract: Using multi reference configuration interaction methodology in connection with a large basis set, we show that GeO{sup 2+} is a metastable species either in the ground or in the electronically excited states. This confirms the observation of this dication in gas phase by mass spectrometry. In addition, we derived a set of accurate spectroscopic terms for GeO{sup 2+} bound states. At the MRCI/aug-cc-pV5Z level of theory, the adiabatic double ionization energy of GeO is computed to be ∼28.93 eV.

  12. Unusual hydroxyl migration in the fragmentation of β-alanine dication in the gas phase.

    Science.gov (United States)

    Piekarski, Dariusz Grzegorz; Delaunay, Rudy; Maclot, Sylvain; Adoui, Lamri; Martín, Fernando; Alcamí, Manuel; Huber, Bernd A; Rousseau, Patrick; Domaracka, Alicja; Díaz-Tendero, Sergio

    2015-07-14

    We present a combined experimental and theoretical study of the fragmentation of doubly positively charged β-alanine molecules in the gas phase. The dissociation of the produced dicationic molecules, induced by low-energy ion collisions, is analysed by coincidence mass spectrometric techniques; the coupling with ab initio molecular dynamics simulations allows rationalisation of the experimental observations. The present strategy gives deeper insights into the chemical mechanisms of multiply charged amino acids in the gas phase. In the case of the β-alanine dication, in addition to the expected Coulomb explosion and hydrogen migration processes, we have found evidence of hydroxyl-group migration, which leads to unusual fragmentation products, such as hydroxymethyl cation, and is necessary to explain some of the observed dominant channels.

  13. Improved gas installations and services. Phase 1: Analysis project. Part report

    International Nuclear Information System (INIS)

    Nielsen, K.J.

    1996-05-01

    As Danish gas companies receive a large number of complaints related to the installation and operation of gas installations it was suggested that a course for personnel should be established in order to raise the standard of services and installation requirements. The first phase of the described project was to evaluate the quality of the gas installers' services so as to determine which aspects of installation and services should be emphasized during such a course. Interviews were carried out and questionnaires (illustrated within the document) sent out to installaters etc. Recommendations include that the level of information given to customers should be raised, also in relation to maintenance, and that installation should be improved. Analyses of the degree of customers' satisfaction, of the nature of the quality of services etc. expected, subjects for further training in this area and details of the training system are dealt with

  14. Phase diagram and universality of the Lennard-Jones gas-liquid system

    KAUST Repository

    Watanabe, Hiroshi

    2012-01-01

    The gas-liquid phase transition of the three-dimensional Lennard-Jones particles system is studied by molecular dynamics simulations. The gas and liquid densities in the coexisting state are determined with high accuracy. The critical point is determined by the block density analysis of the Binder parameter with the aid of the law of rectilinear diameter. From the critical behavior of the gas-liquid coexisting density, the critical exponent of the order parameter is estimated to be β = 0.3285(7). Surface tension is estimated from interface broadening behavior due to capillary waves. From the critical behavior of the surface tension, the critical exponent of the correlation length is estimated to be ν = 0.63(4). The obtained values of β and ν are consistent with those of the Ising universality class. © 2012 American Institute of Physics.

  15. The French experience concerning the contamination by inactive and radioactive impurities and the purification of the cover gas of LMFBRs

    International Nuclear Information System (INIS)

    Michaille, P.; Clerc, R.

    1987-01-01

    With regard to the problems related to the cover gas of LMFBRs, the French position based on the experience of RAPSODIE and PHENIX can be summarized as follows: 1. No particular difficulty has been encountered with impurities such as air. The consequences of lubricants leaks were limited to the maintenance of big components. 2. Concerning the contamination by radioactive species, the main source in the reactor tank is 23 Ne, but fortunately its half decay period is very short (38 s). Two managements of fuel failures were experienced. On RAPSODIE, the failures were numerous for experimental purpose and - in the absence of an efficient localization device - often simultaneous. On PHENIX, the fuel failure rate appears to be very low. Furthermore, the gas analysis unit of the fuel failure localization device (LRG/gas) has been improved steadily, which permits to localize and follow the evolution of each individual failed sub-assembly from the very beginning of the clad failure. For both of the reactors, leaks through the roof were observed, for which solutions were found. 3. The analysis equipment of RAPSODIE and PHENIX evolved to account for: the needs of the operator; experimental programs. The experience gained permitted to select for SUPER PHENIX a simple instrumentation. 4. Limited efforts have been paid to the purification techniques towards the fission products: On RAPSODIE, the use of helium as cover gas allowed to use trapping with charcoal cooled with liquid nitrogen with a high efficiency not only towards xenons, but also kryptons. On PHENIX, it is not necessary to trap krypton: the release rates of 85 Kr (T1/2=10,4 a) are very low, of the same order as 37 Ar (T1/2=35 d) produced by activation, and the fuel failure localization is not performed by gas tagging. Therefore, cooled charcoal adsorption is sufficient. For experimental purpose, a cryogenic distillation column has been installed at PHENIX, but has not yet been put into operation except for testing

  16. Conformational Study of DNA Sugars: from the Gas Phase to Solution

    Science.gov (United States)

    Uriarte, Iciar; Vallejo-López, Montserrat; Cocinero, Emilio J.; Corzana, Francisco; Davis, Benjamin G.

    2017-06-01

    Sugars are versatile molecules that play a variety of roles in the organism. For example, they are important in energy storage processes or as structural scaffolds. Here, we focus on the monosaccharide present in DNA by addressing the conformational and puckering properties in the gas phase of α- and β-methyl-2-deoxy-ribofuranoside and α- and β-methyl-2-deoxy-ribopiranoside. Other sugars have been previously studied in the gas phase The work presented here stems from a combination of chemical synthesis, ultrafast vaporization methods, supersonic expansions, microwave spectroscopy (both chirped-pulsed and Balle-Flygare cavity-based spectrometers) and NMR spectroscopy. Previous studies in the gas phase had been performed on 2-deoxyribose, but only piranose forms were detected. However, thanks to the combination of these techniques, we have isolated and characterized for the first time the conformational landscape of the sugar present in DNA in its biologically relevant furanose form. Our gas phase study serves as a probe of the conformational preferences of these biomolecules under isolation conditions. Thanks to the NMR experiments, we can characterize the favored conformations in solution and extract the role of the solvent in the structure and puckering of the monosaccharides. E. J. Cocinero, A. Lesarri, P. Écija, F. J. Basterretxea, J.-U. Grabow, J. A. Fernández, F. Castaño, Angew. Chem. Int. Edit. 2012, 51, 3119. P. Écija, I. Uriarte, L. Spada, B. G. Davis, W. Caminati, F. J. Basterretxea, A. Lesarri, E. J. Cocinero, Chem. Commun. 2016, 52, 6241. I. Peña, E. J. Cocinero, C. Cabezas, A. Lesarri, S. Mata, P. Écija, A. M. Daly, Á. Cimas, C. Bermúdez, F. J. Basterretxea, S. Blanco, J. A. Fernández, J. C. López, F. Castaño, J. L. Alonso, Angew. Chem. Int. Edit. 2013, 52, 11840.

  17. Gas Phase Transport, Adsorption and Surface Diffusion in Porous Glass Membrane

    Czech Academy of Sciences Publication Activity Database

    Yang, J.; Čermáková, Jiřina; Uchytil, Petr; Hamel, Ch.; Seidel-Morgenstern, A.

    2005-01-01

    Roč. 104, 2-4 (2005), s. 344-351 ISSN 0920-5861. [International Conference on Catalysis in Membrane Reactors /6./. Lahnstein, 06.07.2004-09.07.2004] R&D Projects: GA AV ČR(CZ) IAA4072402 Institutional research plan: CEZ:AV0Z40720504 Keywords : gas phase transport * vycor glass * adsorption Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.365, year: 2005

  18. Method and apparatus for selective capture of gas phase analytes using metal .beta.-diketonate polymers

    Science.gov (United States)

    Harvey, Scott D [Kennewick, WA

    2011-06-21

    A process and sensor device are disclosed that employ metal .beta.-diketonate polymers to selectively capture gas-phase explosives and weaponized chemical agents in a sampling area or volume. The metal .beta.-diketonate polymers can be applied to surfaces in various analytical formats for detection of: improvised explosive devices, unexploded ordinance, munitions hidden in cargo holds, explosives, and chemical weapons in public areas.

  19. Unexpected epoxide formation in the gas-phase photooxidation of isoprene

    DEFF Research Database (Denmark)

    Paulot, Fabien; Crounse, John D; Kjaergaard, Henrik G

    2009-01-01

      Emissions of nonmethane hydrocarbon compounds to the atmosphere from the biosphere exceed those from anthropogenic activity. Isoprene, a five-carbon diene, contributes more than 40% of these emissions. Once emitted to the atmosphere, isoprene is rapidly oxidized by the hydroxyl radical OH. We...... per year-of these epoxides to the atmosphere. The discovery of these highly soluble epoxides provides a missing link tying the gas-phase degradation of isoprene to the observed formation of organic aerosols....

  20. Theoretical Studies of Gas Phase Elementary and Carbon Nanostructure Growth Reactions

    Science.gov (United States)

    2013-09-19

    photodissociation reactions of ketene, methylamine, formic acid , methyl ethyl ketone, acetone and NO3. For instance, for NO3, a totally unknown...to photodissociation reactions of ketene, methylamine, formic acid , methyl ethyl ketone, acetone and NO3. For instance, for NO3, a totally unknown...THEORETICAL STUDIES OF GAS PHASE ELEMENTARY AND CARBON NANOSTRUCTURE GROWTH REACTIONS KEIJI MOROKUMA EMORY UNIVERSITY 09/19/2013 Final Report

  1. Position for determining gas-phase volatile organic compound concentrations in transuranic waste containers. Revision 2

    International Nuclear Information System (INIS)

    Connolly, M.J.; Liekhus, K.J.

    1998-06-01

    In the conditional no-migration determination (NMD) for the test phase of the Waste Isolation Pilot Plant (WIPP), the US Environmental Protection Agency (EPA) imposed certain conditions on the US Department of Energy (DOE) regarding gas phase volatile organic compound (VOC) concentrations in the void space of transuranic (TRU) waste containers. Specifically, the EPA required the DOE to ensure that each waste container has no layer of confinement that contains flammable mixtures of gases or mixtures of gases that could become flammable when mixed with air. The EPA also required that sampling of the headspace of waste containers outside inner layers of confinement be representative of the entire void space of the container. The EPA stated that all layers of confinement in a container would have to be sampled until DOE can demonstrate to the EPA that sampling of all layers is either unnecessary or can be safely reduced. A test program was conducted at the Idaho National Engineering and Environmental Laboratory (INEEL) to demonstrate that the gas phase VOC concentration in the void space of each layer of confinement in vented drums can be estimated from measured drum headspace using a theoretical transport model and that sampling of each layer of confinement is unnecessary. This report summarizes the studies performed in the INEEL test program and extends them for the purpose of developing a methodology for determining gas phase VOC concentrations in both vented and unvented TRU waste containers. The methodology specifies conditions under which waste drum headspace gases can be said to be representative of drum gases as a whole and describes a method for predicting drum concentrations in situations where the headspace concentration is not representative. The methodology addresses the approach for determining the drum VOC gas content for two purposes: operational period drum handling and operational period no-migration calculations

  2. Numerical simulation of gas-contaminated refrigerant two-phase flow through

    Czech Academy of Sciences Publication Activity Database

    Vinš, Václav; Hrubý, Jan; Vacek, V.

    2010-01-01

    Roč. 53, 23-24 (2010), s. 5430-5439 ISSN 0017-9310 R&D Projects: GA ČR GA101/09/1633 Institutional research plan: CEZ:AV0Z20760514 Keywords : capillary tube * henry’s law * non-condensing gases Subject RIV: BJ - Thermodynamics Impact factor: 1.898, year: 2010 http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6V3H-50N9C3K-8-2X&_cdi=5731&_user=640952&_pii=S0017931010003819&_origin=search&_coverDate=11%2F30%2F2010&_sk=999469976&view=c&wchp=dGLzVtz-zSkWA&md5=3b8d5c97caaa70e52da990c8ffac4421&ie=/sdarticle.pdf

  3. Field tests of a chemiresistor sensor for in-situ monitoring of vapor-phase contaminants

    Science.gov (United States)

    Ho, C.; McGrath, L.; Wright, J.

    2003-04-01

    An in-situ chemiresistor sensor has been developed that can detect volatile organic compounds in subsurface environmental applications. Several field tests were conducted in 2001 and 2002 to test the reliability, operation, and performance of the in-situ chemiresistor sensor system. The chemiresistor consists of a carbon-loaded polymer deposited onto a microfabricated circuit. The polymer swells reversibly in the presence of volatile organic compounds as vapor-phase molecules absorb into the polymer, causing a change in the electrical resistance of the circuit. The change in resistance can be calibrated to known concentrations of analytes, and arrays of chemiresistors can be used on a single chip to aid in discrimination. A waterproof housing was constructed to allow the chemiresistor to be used in a variety of media including air, soil, and water. The integrated unit, which can be buried in soils or emplaced in wells, is connected via cable to a surface-based solar-powered data logger. A cell-phone modem is used to automatically download the data from the data logger on a periodic basis. The field tests were performed at three locations: (1) Edwards Air Force Base, CA; (2) Nevada Test Site; and (3) Sandia's Chemical Waste Landfill near Albuquerque, NM. The objectives of the tests were to evaluate the ruggedness, longevity, operation, performance, and engineering requirements of these sensors in actual field settings. Results showed that the sensors could be operated continuously for long periods of time (greater than a year) using remote solar-powered data-logging stations with wireless telemetry. The sensor housing, which was constructed of 304 stainless steel, showed some signs of corrosion when placed in contaminated water for several months, but the overall integrity was maintained. The detection limits of the chemiresistors were generally found to be near 0.1% of the saturated vapor pressure of the target analyte in controlled laboratory conditions (e

  4. Radical Generation from the Gas-Phase Activation of Ionized Lipid Ozonides

    Science.gov (United States)

    Ellis, Shane R.; Pham, Huong T.; in het Panhuis, Marc; Trevitt, Adam J.; Mitchell, Todd W.; Blanksby, Stephen J.

    2017-07-01

    Reaction products from the ozonolysis of unsaturated lipids at gas-liquid interfaces have the potential to significantly influence the chemical and physical properties of organic aerosols in the atmosphere. In this study, the gas-phase dissociation behavior of lipid secondary ozonides is investigated using ion-trap mass spectrometry. Secondary ozonides were formed by reaction between a thin film of unsaturated lipids (fatty acid methyl esters or phospholipids) with ozone before being transferred to the gas phase as [M + Na]+ ions by electrospray ionization. Activation of the ionized ozonides was performed by either energetic collisions with helium buffer-gas or laser photolysis, with both processes yielding similar product distributions. Products arising from the decomposition of the ozonides were characterized by their mass-to-charge ratio and subsequent ion-molecule reactions. Product assignments were rationalized as arising from initial homolysis of the ozonide oxygen-oxygen bond with subsequent decomposition of the nascent biradical intermediate. In addition to classic aldehyde and carbonyl oxide-type fragments, carbon-centered radicals were identified with a number of decomposition pathways that indicated facile unimolecular radical migration. These findings reveal that photoactivation of secondary ozonides formed by the reaction of aerosol-bound lipids with tropospheric ozone may initiate radical-mediated chemistry within the particle resulting in surface modification.

  5. Liquid and gas phase NMR spectra of 13CH313CHO acetaldehyde

    Science.gov (United States)

    Makulski, Włodzimierz; Wikieł, Agata J.

    2018-01-01

    The gas phase NMR experiments perform a vital role in establishing the magnetic shielding and spin-spin coupling constants which are free from intermolecular interactions, equivalent to the parameter of isolated molecules. This work is concerned with an acetaldehyde molecule. Small amounts of acetaldehyde 13CH313CHO in gaseous matrices of CO2 and Xe were studied using high-precision 1H and 13C NMR measurements. Results were extrapolated to the zero-density limit permitting the determinations of the 1H and 13C absolute nuclear magnetic shielding of an isolated acetaldehyde molecule. The difference between the experimental and recent theoretical DFT results is discussed. Several samples of 13CH313CHO dissolved in popular organic and inorganic solvents were also investigated. Gas-to-solution shifts show the influence of the association process when acetaldehyde is transferred from gas to liquid state. Several spin-spin coupling constants in the gas phase and in different solvents were precisely measured.

  6. Functionalized silica aerogels for gas-phase purification, sensing, and catalysis: A review

    Energy Technology Data Exchange (ETDEWEB)

    Amonette, James E.; Matyáš, Josef

    2017-09-01

    Silica aerogels have a rich history and a unique, fascinating gas-phase chemistry that has lent them to many diverse applications. This review starts with a brief discussion of the fundamental issues driving the movement of gases in silica aerogels and then proceeds to provide an overview of the work that has been done with respect to the purification of gases, sensing of individual gases, and uses of silica aerogels as catalysts for gas-phase reactions. Salient features of the research behind these different applications are presented, and, where appropriate, critical aspects that affect the practical use of the aerogels are noted. Specific sections under the gas-purification category focus on the removal of airborne nanoparticles, carbon dioxide, volatile organic compounds, sulfur gases and radioactive iodine from gas streams. The use of silica aerogels as sensors for humidity, oxygen, hydrocarbons, volatile acids and bases, various non-ammoniacal nitrogen gases, and viral particles is discussed. With respect to catalysis, the demonstrated use of silica aerogels as supports for oxidation, Fischer-Tropsch, alkane isomerization, and hydrogenation reactions is reviewed, along with a section on untested catalytic formulations involving silica aerogels. A short section focuses on recent developments in thermomolecular Knudsen compressor pumps using silica aerogel membranes. The review continues with an overview of the production methods, locations of manufacturing facilities globally, and a brief discussion of the economics before concluding with a few remarks about the present and future trends revealed by the work presented.

  7. Source reconciliation of atmospheric gas-phase and particle-phase pollutants during a severe photochemical smog episode.

    Science.gov (United States)

    Schauer, James J; Fraser, Matthew P; Cass, Glen R; Simoneit, Bernd R T

    2002-09-01

    A comprehensive organic compound-based receptor model is developed that can simultaneously apportion the source contributions to atmospheric gas-phase organic compounds, semivolatile organic compounds, fine particle organic compounds, and fine particle mass. The model is applied to ambient data collected at four sites in the south coast region of California during a severe summertime photochemical smog episode, where the model determines the direct primary contributions to atmospheric pollutants from 11 distinct air pollution source types. The 11 sources included in the model are gasoline-powered motor vehicle exhaust, diesel engine exhaust, whole gasoline vapors, gasoline headspace vapors, organic solvent vapors, whole diesel fuel, paved road dust, tire wear debris, meat cooking exhaust, natural gas leakage, and vegetative detritus. Gasoline engine exhaust plus whole gasoline vapors are the predominant sources of volatile organic gases, while gasoline and diesel engine exhaust plus diesel fuel vapors dominate the emissions of semivolatile organic compounds from these sources during the episode studied at all four air monitoring sites. The atmospheric fine particle organic compound mass was composed of noticeable contributions from gasoline-powered motor vehicle exhaust, diesel engine exhaust, meat cooking, and paved road dust with smaller but quantifiable contributions from vegetative detritus and tire wear debris. In addition, secondary organic aerosol, which is formed from the low-vapor pressure products of gas-phase chemical reactions, is found to be a major source of fine particle organic compound mass under the severe photochemical smog conditions studied here. The concentrations of secondary organic aerosol calculated in the present study are compared with previous fine particle source apportionment results for less intense photochemical smog conditions. It is shown that estimated secondary organic aerosol concentrations correlate fairly well with the

  8. Nitric oxide contamination of hospital compressed air improves gas exchange in patients with acute lung injury.

    Science.gov (United States)

    Tan, P Seow Koon; Genc, F; Delgado, E; Kellum, J A; Pinsky, M R

    2002-08-01

    We tested the hypothesis that NO contamination of hospital compressed air also improves PaO(2) in patients with acute lung injury (ALI) and following lung transplant (LTx). Prospective clinical study. Cardiothoracic intensive care unit. Subjects following cardiac surgery (CABG, n=7); with ALI (n=7), and following LTx (n=5). Four sequential 15-min steps at a constant FiO(2) were used: hospital compressed air-O(2) (H1), N(2)-O(2) (A1), repeat compressed air-O(2) (H2), and repeat N(2)-O(2) (A2). NO levels were measured from the endotracheal tube. Cardiorespiratory values included PaO(2) were measured at the end of each step. FiO(2) was 0.46+/-0.05, 0.53+/-0.15, and 0.47+/-0.06 (mean+/-SD) for three groups, respectively. Inhaled NO levels during H1 varied among subjects (30-550 ppb, 27-300 ppb, and 5-220 ppb, respectively). Exhaled NO levels were not detected in 4/7 of CABG (0-300 ppb), 3/6 of ALI (0-140 ppb), and 3/5 of LTx (0-59 ppb) patients during H1, whereas during A1 all but one patient in ALI and three CABG patients had measurable exhaled NO levels (P<0.05). Small but significant decreases in PaO(2) occurred for all groups from H1 to A1 and H2 to A2 (132-99 Torr and 128-120 Torr, P <0.01, respectively). There was no correlation between inhaled NO during H1 and exhaled NO during A1 or the change in PaO(2) from H1 to A1. Low-level NO contamination improves PaO(2) in patients with ALI and following LTx.

  9. Modelling of stratified gas-liquid two-phase flow in horizontal circular pipes

    International Nuclear Information System (INIS)

    Sampaio, P.A.B. de; Faccini, J.L.H.; Su, J.

    2006-01-01

    This paper reports numerical and experimental investigation of stratified gas-liquid two-phase flow in horizontal circular pipes. The Reynolds average Navier-Stokes equations (RANS) with κ ω model development stratified gas-liquid two-phase flow are solved by using the finite element methods. A smooth interface surface is assumed without considered the effects of the interfacial waves. The continuity of the shear stress across the interface is enforced with the continuity of the velocity being automatically satisfied by the variational formulation. For it is given position and interface and longitudinal pressure gradient, an inner iteration loop runs to solve nonlinear equations the Newton-Raphson scheme is used to solve the transcendental equations by an outer iteration to determinate the interface position in a 5.2 mm ID circular pipe was measured experimentally by the ultrasonic ultra pulse-echo technique. The numeral were also compared with results in 21 mm ID circular pipe report by Masala (2004). The good agreement between the numerical and experimental results indicates that κ ω model can be applied for the numerical simulation of stratified gas-liquid two phase flow. (author)

  10. Temperature dependence of gas-phase polycyclic aromatic hydrocarbon and organochlorine pesticide concentrations in Chicago air

    Science.gov (United States)

    Sofuoglu, Aysun; Odabasi, Mustafa; Tasdemir, Yucel; Khalili, Nasrin R.; Holsen, Thomas M.

    The temperature dependence of gas-phase atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides measured in Chicago, IL between June and October 1995 were investigated using plots of the natural logarithm of partial pressures (ln P) vs. reciprocal mean temperatures (1/ T). For the eight lowest molecular weight PAHs, temperature dependence was statistically significant (at the 95% confidence level) and temperature accounted for 23-49% of the variability in gas-phase concentrations. The relatively higher slopes for most of the PAHs suggested that volatilization from local sources and short-range transport influenced their concentrations. For pesticides, temperature dependence was statistically significant for DDD and for trans-nonachlor (at the 95% and 90% confidence levels), and was not statistically significant for the other five compounds (2-18% of the variability in their gas-phase concentrations). The relatively lower slopes for individual pesticides suggested that they have mostly non-urban and distant sources. Results of back trajectory analyses suggested that the region, southwest of Chicago, might be an important local or regional source sector for PAHs and organochlorine pesticides. No statistically significant relationship was observed between wind speed and PAH or pesticide concentrations. None of the variables (temperature, wind speed, wind direction, local and regional sources) could fully explain the variation in their concentrations measured in Chicago, therefore, this variation can be attributed to the combined effect of those factors.

  11. Thermodynamic analysis of fuels in gas phase: ethanol, gasoline and ethanol - gasoline predicted by DFT method.

    Science.gov (United States)

    Neto, A F G; Lopes, F S; Carvalho, E V; Huda, M N; Neto, A M J C; Machado, N T

    2015-10-01

    This paper presents a theoretical study using density functional theory to calculate thermodynamics properties of major molecules compounds at gas phase of fuels like gasoline, ethanol, and gasoline-ethanol mixture in thermal equilibrium on temperature range up to 1500 K. We simulated a composition of gasoline mixture with ethanol for a thorough study of thermal energy, enthalpy, Gibbs free energy, entropy, heat capacity at constant pressure with respect to temperature in order to study the influence caused by ethanol as an additive to gasoline. We used semi-empirical computational methods as well in order to know the efficiency of other methods to simulate fuels through this methodology. In addition, the ethanol influence through the changes in percentage fractions of chemical energy released in combustion reaction and the variations on thermal properties for autoignition temperatures of fuels was analyzed. We verified how ethanol reduces the chemical energy released by gasoline combustion and how at low temperatures the gas phase fuels in thermal equilibrium have similar thermodynamic behavior. Theoretical results were compared with experimental data, when available, and showed agreement. Graphical Abstract Thermodynamic analysis of fuels in gas phase.

  12. The influence of non condensible gas on two phase critical flow

    International Nuclear Information System (INIS)

    Celata, G.P.; Cumo, M.; D'Annibale, F.; Farello, G.E.

    1987-01-01

    With reference to Loss-of-Coolant Accidents in Pressurized Water Reactors and in the frame of the wide scientific landscape of blowdown experiments aiming to the improvement of two-phase critical flows knowledge, it is of interest the analysis of non condensible gas influence on the critical flow (radiolytic gases,metal-water reactions products etc.). The present paper deals with an experiment referring to two-phase steam-water critical flows from long tubes, in which known air flowrates are injected in the stagnation region. The aim of the experiment is to detect the influence of non-condensible gas on the two-phase critical flow behaviour (critical mass flow rate, pressure and temperature profiles along the discharge channel etc.) as well as to individuate the limit, in terms of air concentration, beyond which the critical flow is affected by the presence of the gas. The employed test section is a vertical, circular duct channel with an inner diameter of 4.6 mm and a length of 1500 mm (L/D = 325). Results of initially subcooled liquid experiments (together with some data of satured liquid discharges), up to 15 bars are reported with the analysis of non-condensible effects in the different stagnation conditions

  13. Improved machine learning method for analysis of gas phase chemistry of peptides

    Directory of Open Access Journals (Sweden)

    Ahn Natalie

    2008-12-01

    Full Text Available Abstract Background Accurate peptide identification is important to high-throughput proteomics analyses that use mass spectrometry. Search programs compare fragmentation spectra (MS/MS of peptides from complex digests with theoretically derived spectra from a database of protein sequences. Improved discrimination is achieved with theoretical spectra that are based on simulating gas phase chemistry of the peptides, but the limited understanding of those processes affects the accuracy of predictions from theoretical spectra. Results We employed a robust data mining strategy using new feature annotation functions of MAE software, which revealed under-prediction of the frequency of occurrence in fragmentation of the second peptide bond. We applied methods of exploratory data analysis to pre-process the information in the MS/MS spectra, including data normalization and attribute selection, to reduce the attributes to a smaller, less correlated set for machine learning studies. We then compared our rule building machine learning program, DataSqueezer, with commonly used association rules and decision tree algorithms. All used machine learning algorithms produced similar results that were consistent with expected properties for a second gas phase mechanism at the second peptide bond. Conclusion The results provide compelling evidence that we have identified underlying chemical properties in the data that suggest the existence of an additional gas phase mechanism for the second peptide bond. Thus, the methods described in this study provide a valuable approach for analyses of this kind in the future.

  14. New quantum chemical computations of formamide deuteration support gas-phase formation of this prebiotic molecule

    Science.gov (United States)

    Skouteris, D.; Vazart, F.; Ceccarelli, C.; Balucani, N.; Puzzarini, C.; Barone, V.

    2017-06-01

    Based on recent work, formamide might be a potentially very important molecule in the emergence of terrestrial life. Although detected in the interstellar medium for decades, its formation route is still debated, whether in the gas phase or on the dust grain surfaces. Molecular deuteration has proven to be, in other cases, an efficient way to identify how a molecule is synthesized. For formamide, new published observations towards the IRAS16293-2422 B hot corino show that its three deuterated forms have all the same deuteration ratio, 2-5 per cent and that this is a factor of 3-8 smaller than that measured for H2CO towards the IRAS16293-2422 protostar. Following a previous work on the gas-phase formamide formation via the reaction NH2 + H2CO → HCONH2 + H, we present here new calculations of the rate coefficients for the production of monodeuterated formamide through the same reaction, starting from monodeuterated NH2 or H2CO. Some misconceptions regarding our previous treatment of the reaction are also cleared up. The results of the new computations show that, at the 100 K temperature of the hot corino, the rate of deuteration of the three forms is the same, within 20 per cent. On the contrary, the reaction between non-deuterated species proceeds three times faster than that with deuterated ones. These results confirm that a gas-phase route for the formation of formamide is perfectly in agreement with the available observations.

  15. The Gas-Phase Formation of Methyl Formate in Hot Molecular Cores

    Science.gov (United States)

    Horn, Anne; Møllendal, Harald; Sekiguchi, Osamu; Uggerud, Einar; Roberts, Helen; Herbst, Eric; Viggiano, A. A.; Fridgen, Travis D.

    2004-08-01

    Methyl formate, HCOOCH3, is a well-known interstellar molecule prominent in the spectra of hot molecular cores. The current view of its formation is that it occurs in the gas phase from precursor methanol, which is synthesized on the surfaces of grain mantles during a previous colder era and evaporates while temperatures increase during the process of high-mass star formation. The specific reaction sequence thought to form methyl formate, the ion-molecule reaction between protonated methanol and formaldehyde followed by dissociative recombination of the protonated ion [HCO(H)OCH3]+, has not been studied in detail in the laboratory. We present here the results of both a quantum chemical study of the ion-molecule reaction between [CH3OH2]+ and H2CO as well as new experimental work on the system. In addition, we report theoretical and experimental studies for a variety of other possible gas-phase reactions leading to ion precursors of methyl formate. The studied chemical processes leading to methyl formate are included in a chemical model of hot cores. Our results show that none of these gas-phase processes produces enough methyl formate to explain its observed abundance.

  16. Enantiomer-Selective Photo-Induced Reaction of Protonated Tryptophan with Disaccharides in the Gas Phase

    Science.gov (United States)

    Doan, Thuc N.; Fujihara, Akimasa

    2018-03-01

    In order to investigate chemical evolution in interstellar molecular clouds, enantiomer-selective photo-induced chemical reactions between an amino acid and disaccharides in the gas phase were examined using a tandem mass spectrometer containing an electrospray ionization source and a cold ion trap. Ultraviolet photodissociation mass spectra of cold gas-phase noncovalent complexes of protonated tryptophan (Trp) enantiomers with disaccharides consisting of two d-glucose units, such as d-maltose or d-cellobiose, were obtained by photoexcitation of the indole ring of Trp. NH2CHCOOH loss via cleavage of the Cα-Cβ bond in Trp induced by hydrogen atom transfer from the NH3 + group of a protonated Trp was observed in a noncovalent heterochiral H+( l-Trp)( d-maltose) complex. In contrast, a photo-induced chemical reaction forming the product ion with m/z 282 occurs in homochiral H+( d-Trp)( d-maltose). For d-cellobiose, both NH2CHCOOH elimination and the m/z 282 product ion were observed, and no enantiomer-selective phenomena occurred. The m/z 282 product ion indicates that the photo-induced C-glycosylation, which links d-glucose residues to the indole moiety of Trp via a C-C bond, can occur in cold gas-phase noncovalent complexes, and its enantiomer-selectivity depends on the structure of the disaccharide.

  17. Revision of the gas-phase acidity scale below 300 kcal mol(-1).

    Science.gov (United States)

    Leito, Ivo; Raamat, Elin; Kütt, Agnes; Saame, Jaan; Kipper, Karin; Koppel, Ilmar A; Koppel, Ivar; Zhang, Min; Mishima, Masaaki; Yagupolskii, Lev M; Garlyauskayte, Romute Yu; Filatov, Andrey A

    2009-07-23

    The gas-phase acidity (GA) scale from (CF(3)CO)(2)NH to (C(2)F(5)SO(2))(2)NH--about a 24 kcal mol(-1) range of gas-phase acidities--was reexamined using the Fourier transform ion cyclotron resonance equilibrium measurement approach. Some additions and modifications to the standard methodology of GA measurements were introduced (estimation of partial pressures from mass spectra of the compounds, instead of the pressure gauge readings and use of long reaction times) to achieve higher reliability. Gas-phase acidities of 18 compounds were determined for the first time. The results reveal a contraction of the previously published values in this part of the scale. In particular, the GA values of (CF(3)SO(2))(2)NH and (C(2)F(5)SO(2))(2)NH (important components of lithium ion battery electrolytes and ionic liquids) were revised toward stronger acidities from 291.8 kcal mol(-1) to 286.5 kcal mol(-1) and from 289.4 kcal mol(-1) to 283.7 kcal mol(-1) (i.e., by 5.3 and 5.7 kcal mol(-1)), respectively. Experimental and computational evidence is presented in support of the current results.

  18. Systematic Search for Chemical Reactions in Gas Phase Contributing to Methanol Formation in Interstellar Space.

    Science.gov (United States)

    Gamez-Garcia, Victoria G; Galano, Annia

    2017-10-05

    A massive search for chemical routes leading to methanol formation in gas phase has been conducted using computational chemistry, at the CBS-QB3 level of theory. The calculations were performed at five different temperatures (100, 80, 50, 20, and 10 K) and at three pressures (0.1, 0.01, and 0.001 atm) for each temperature. The search was focused on identifying reactions with the necessary features to be viable in the interstellar medium (ISM). A searching strategy was applied to that purpose, which allowed to reduce an initial set of 678 possible reactions to a subset of 11 chemical routes that are recommended, for the first time, as potential candidates for contributing to methanol formation in the gas phase of the ISM. They are all barrier-less, and thus they are expected to take place at collision rates. Hopefully, including these reactions in the currently available models, for the gas-phase methanol formation in the ISM, would help improving the predicted fractional abundance of this molecule in dark clouds. Further investigations, especially those dealing with grain chemistry and electronic excited states, would be crucial to get a complete picture of the methanol formation in the ISM.

  19. Probing the regional distribution of pulmonary gas exchange through single-breath gas- and dissolved-phase 129Xe MR imaging.

    Science.gov (United States)

    Kaushik, S Sivaram; Freeman, Matthew S; Cleveland, Zackary I; Davies, John; Stiles, Jane; Virgincar, Rohan S; Robertson, Scott H; He, Mu; Kelly, Kevin T; Foster, W Michael; McAdams, H Page; Driehuys, Bastiaan

    2013-09-01

    Although some central aspects of pulmonary function (ventilation and perfusion) are known to be heterogeneous, the distribution of diffusive gas exchange remains poorly characterized. A solution is offered by hyperpolarized 129Xe magnetic resonance (MR) imaging, because this gas can be separately detected in the lung's air spaces and dissolved in its tissues. Early dissolved-phase 129Xe images exhibited intensity gradients that favored the dependent lung. To quantitatively corroborate this finding, we developed an interleaved, three-dimensional radial sequence to image the gaseous and dissolved 129Xe distributions in the same breath. These images were normalized and divided to calculate "129Xe gas-transfer" maps. We hypothesized that, for healthy volunteers, 129Xe gas-transfer maps would retain the previously observed posture-dependent gradients. This was tested in nine subjects: when the subjects were supine, 129Xe gas transfer exhibited a posterior-anterior gradient of -2.00 ± 0.74%/cm; when the subjects were prone, the gradient reversed to 1.94 ± 1.14%/cm (P gas-transfer maps also exhibited significant heterogeneity, as measured by the coefficient of variation, that correlated with subject total lung capacity (r = 0.77, P = 0.015). Gas-transfer intensity varied nonmonotonically with slice position and increased in slices proximal to the main pulmonary arteries. Despite substantial heterogeneity, the mean gas transfer for all subjects was 1.00 ± 0.01 while supine and 1.01 ± 0.01 while prone (P = 0.25), indicating good "matching" between gas- and dissolved-phase distributions. This study demonstrates that single-breath gas- and dissolved-phase 129Xe MR imaging yields 129Xe gas-transfer maps that are sensitive to altered gas exchange caused by differences in lung inflation and posture.

  20. Evaluation of false alarm on the total body contamination monitor (personnel monitor PM 50 I) at RSG-GAS

    International Nuclear Information System (INIS)

    Suryawati, S.; Akhmad, Y.R.; Nugroho, L.

    1998-01-01

    Evaluation of false alarm on the total body contamination monitor PM 50 I by sensitivity testing, measurements of the room background, shoes covers and personal lab clothes at MPR-GAS on operation and shutdown condition have been made. Evaluation to the alarm setting limit value also is carried out. On the condition of reactor was not operated the false alarm as an indication happened contamination came from many materials like shoes covers which have a high electrostaticity and dirty condition, therefore it produces a high background counting upper to it contamination limit value. this case happened because there was low background counting of the measurement object and the contamination monitor had i high sensitivity, so the background counting of the measurement object gives a contribution for the total counting. On the high power condition of thr reactor operation, the background counting of the room was high, so the contamination limit value shall be changed to the higher value to follow up on the average background counting. This case caused the sensitivity of the detector decreased so the background counting of the measuring object was not give a significance contribution counting value of the total counting measurement value. The observation of the alarm setting limit value in reactor condition was not operated, based to sensitivity testing, observation of the background counting the room, of contamination measurement of the many contaminated material show that the sensitivity of the detector was exactly good, so that the alarm setting limit value in the shut down reactor condition was optimally operated using the old setting made by supplier or setting value in first commissioning. These setting value are as following : 50 cps for the case detector (detector Nr.1) until to the hand detector (detector Nr.10), 75 cps for the foot detectors (detector Nr.11) and the head detector (detector Nr.12). Alarm setting limit value for 25 MWth power reactor operation

  1. Ecological and climatic consequences of phase instability of gas hydrates on the ocean bed

    Science.gov (United States)

    Balanyuk, I.; Dmitrievsky, A.; Akivis, T.; Chaikina, O.

    2009-04-01

    energy and gas that leads to explosion. Methane is the main natural source for power engineering specialists. It is transported by pipelines, and gas hydrate is dangerous in this case too. It can block the gas pipeline system forming the so-called "trombus" of "thermal ice". After that the pipes have to be opened. The mess of this strange ice discovered melts immediately releasing methane and water vapor. The trombus formation can be prevented by the temperature increase or the pressure decrease. Both methods are very uncomfortable under the conditions the pipelines work. The better method is thorough drying up of the gas because gas hydrate obviously cannot be formed without water. Gas hydrates attract attention not only as a fuel and chemical stuff but in relation to a serious anxiety of strong ecological and climatic problems that can occur as a result of methane release to the atmosphere due to both gas hydrate deposits development and minor changes in thermodynamic conditions in the vicinity of a threshold of gas hydrate phase stability. One of the most probable causes is the global warming of the Earth due to the hothouse effect because the specific absorption of the Earth heat radiation by methane (radiation effectivity) is 21 times higher than its absorption by carbonic gas. Analysis of the air trapped by polar ice show that contemporary increase of methane concentration in the atmosphere is unexampled for the last 160 thousands of years. The sources of this increase are not clear. Observer and latent methane bursts during natural gas hydrates decomposition can be considered as a probable source. Amount of methane hided in natural gas hydrates is 3000 times higher its amount in the atmosphere. Release of this hothouse potential would have terrible consequences for the humanity. The warming can cause further gas hydrates decomposition and released methane will cause the following warming. Thus, self-accelerating process can start. The most vulnerable for the

  2. Heat transfer characteristics of liquid-gas Taylor flows incorporating microencapsulated phase change materials

    International Nuclear Information System (INIS)

    Howard, J A; Walsh, P A

    2014-01-01

    This paper presents an investigation on the heat transfer characteristics associated with liquid-gas Taylor flows in mini channels incorporating microencapsulated phase change materials (MPCM). Taylor flows have been shown to result in heat transfer enhancements due to the fluid recirculation experienced within liquid slugs which is attributable to the alternating liquid slug and gas bubble flow structure. Microencapsulated phase change materials (MPCM) also offer significant potential with increased thermal capacity due to the latent heat required to cause phase change. The primary aim of this work was to examine the overall heat transfer potential associated with combining these two novel liquid cooling technologies. By investigating the local heat transfer characteristics, the augmentation/degradation over single phase liquid cooling was quantified while examining the effects of dimensionless variables, including Reynolds number, liquid slug length and gas void fraction. An experimental test facility was developed which had a heated test section and allowed MPCM-air Taylor flows to be subjected to a constant heat flux boundary condition. Infrared thermography was used to record high resolution experimental wall temperature measurements and determine local heat transfer coefficients from the thermal entrance point. 30.2% mass particle concentration of the MPCM suspension fluid was examined as it provided the maximum latent heat for absorption. Results demonstrate a significant reduction in experimental wall temperatures associated with MPCM-air Taylor flows when compared with the Graetz solution for conventional single phase coolants. Total enhancement in the thermally developed region is observed to be a combination of the individual contributions due to recirculation within the liquid slugs and also absorption of latent heat. Overall, the study highlights the potential heat transfer enhancements that are attainable within heat exchange devices employing MPCM

  3. Evaluation of Gas Phase Dispersion in Flotation under Predetermined Hydrodynamic Conditions

    Science.gov (United States)

    Młynarczykowska, Anna; Oleksik, Konrad; Tupek-Murowany, Klaudia

    2018-03-01

    Results of various investigations shows the relationship between the flotation parameters and gas distribution in a flotation cell. The size of gas bubbles is a random variable with a specific distribution. The analysis of this distribution is useful to make mathematical description of the flotation process. The flotation process depends on many variable factors. These are mainly occurrences like collision of single particle with gas bubble, adhesion of particle to the surface of bubble and detachment process. These factors are characterized by randomness. Because of that it is only possible to talk about the probability of occurence of one of these events which directly affects the speed of the process, thus a constant speed of flotation process. Probability of the bubble-particle collision in the flotation chamber with mechanical pulp agitation depends on the surface tension of the solution, air consumption, degree of pul aeration, energy dissipation and average feed particle size. Appropriate identification and description of the parameters of the dispersion of gas bubbles helps to complete the analysis of the flotation process in a specific physicochemical conditions and hydrodynamic for any raw material. The article presents the results of measurements and analysis of the gas phase dispersion by the size distribution of air bubbles in a flotation chamber under fixed hydrodynamic conditions. The tests were carried out in the Laboratory of Instrumental Methods in Department of Environmental Engineering and Mineral Processing, Faculty of Mining and Geoengineerin, AGH Univeristy of Science and Technology in Krakow.

  4. Evaluation of Gas Phase Dispersion in Flotation under Predetermined Hydrodynamic Conditions

    Directory of Open Access Journals (Sweden)

    Młynarczykowska Anna

    2018-01-01

    Full Text Available Results of various investigations shows the relationship between the flotation parameters and gas distribution in a flotation cell. The size of gas bubbles is a random variable with a specific distribution. The analysis of this distribution is useful to make mathematical description of the flotation process. The flotation process depends on many variable factors. These are mainly occurrences like collision of single particle with gas bubble, adhesion of particle to the surface of bubble and detachment process. These factors are characterized by randomness. Because of that it is only possible to talk about the probability of occurence of one of these events which directly affects the speed of the process, thus a constant speed of flotation process. Probability of the bubble-particle collision in the flotation chamber with mechanical pulp agitation depends on the surface tension of the solution, air consumption, degree of pul aeration, energy dissipation and average feed particle size. Appropriate identification and description of the parameters of the dispersion of gas bubbles helps to complete the analysis of the flotation process in a specific physicochemical conditions and hydrodynamic for any raw material. The article presents the results of measurements and analysis of the gas phase dispersion by the size distribution of air bubbles in a flotation chamber under fixed hydrodynamic conditions. The tests were carried out in the Laboratory of Instrumental Methods in Department of Environmental Engineering and Mineral Processing, Faculty of Mining and Geoengineerin, AGH Univeristy of Science and Technology in Krakow.

  5. Replacing Natural Gas by Biogas — Determining the Bacterial Contamination of Biogas by PCR

    Directory of Open Access Journals (Sweden)

    Jiřina Čermáková

    2012-01-01

    Full Text Available A promising way of using biogas is to upgrade it to natural gas, which is referred to as Substitute Natural Gas (SNG or biomethane. Biomethane, or biogas, is produced by biological processes of harnessing the ability of microorganisms to degrade organic material to methane. Some of the microorganisms are aerosolized from the digester into the biogas; afterwards a bio-film is formed that attaches to the surfaces of the distribution pipes, and can find it was to the place where the end use of biogas takes place. This paper deals with the detection of microbial species in biogas, their influenceon corrosion and the potential risk that diseases can be spread via biogas using molecular techniques. Using molecular methods, we found that raw biogas contains about 8 million microorganisms per m3, which is most likely the result of microbial transmission from the anaerobic digestion process. Some bacterial species may contribute to the corrosion of pipelines and equipment; others are opportunistic pathogens that can cause toxic reactions. However, most bacterial species, more than 40 % in biogas, are still unknown, as is their influence on the digestion process and on human health. Further studies are needed to better understand the behavior of microorganisms in anaerobic digestion and to preventmicrobial-influenced corrosion and microbial dissemination.

  6. Determination of gas & liquid two-phase flow regime transitions in wellbore annulus by virtual mass force coefficient when gas cut

    Science.gov (United States)

    Qu, Junbo; Yan, Tie; Sun, Xiaofeng; Chen, Ye; Pan, Yi

    2017-10-01

    With the development of drilling technology to deeper stratum, overflowing especially gas cut occurs frequently, and then flow regime in wellbore annulus is from the original drilling fluid single-phase flow into gas & liquid two-phase flow. By using averaged two-fluid model equations and the basic principle of fluid mechanics to establish the continuity equations and momentum conservation equations of gas phase & liquid phase respectively. Relationship between pressure and density of gas & liquid was introduced to obtain hyperbolic equation, and get the expression of the dimensionless eigenvalue of the equation by using the characteristic line method, and analyze wellbore flow regime to get the critical gas content under different virtual mass force coefficients. Results show that the range of equation eigenvalues is getting smaller and smaller with the increase of gas content. When gas content reaches the critical point, the dimensionless eigenvalue of equation has no real solution, and the wellbore flow regime changed from bubble flow to bomb flow. When virtual mass force coefficients are 0.50, 0.60, 0.70 and 0.80 respectively, the critical gas contents are 0.32, 0.34, 0.37 and 0.39 respectively. The higher the coefficient of virtual mass force, the higher gas content in wellbore corresponding to the critical point of transition flow regime, which is in good agreement with previous experimental results. Therefore, it is possible to determine whether there is a real solution of the dimensionless eigenvalue of equation by virtual mass force coefficient and wellbore gas content, from which we can obtain the critical condition of wellbore flow regime transformation. It can provide theoretical support for the accurate judgment of the annular flow regime.

  7. Is it biologically relevant to measure the structures of small peptides in the gas-phase?

    Science.gov (United States)

    Barran, Perdita E.; Polfer, Nick C.; Campopiano, Dominic J.; Clarke, David J.; Langridge-Smith, Patrick R. R.; Langley, Ross J.; Govan, John R. W.; Maxwell, Alison; Dorin, Julia R.; Millar, Robert P.; Bowers, Michael T.

    2005-02-01

    Recent developments in sample introduction of biologically relevant molecules have heralded a new era for gas-phase methods of structural determination. One of the biggest challenges is to relate gas-phase structures, often measured in the absence of water and counter ions, with in vivo biologically active structures. An advantage of gas-phase based techniques is that a given peptide can be analysed in a variety of different forms, for example, as a function of charge state, or with additional water molecules. Molecular modelling can provide insight into experimental findings and help elucidate the differences between structural forms. Combining experiment and theory provides a thorough interrogation of candidate conformations. Here two important naturally occurring peptide systems have been examined in detail and results are assessed in terms of their biological significance. The first of these is gonadotropin-releasing hormone (GnRH), a decapeptide which is the central regulator of the reproductive system in vertebrates. We have examined several naturally occurring variants of this peptide using Ion Mobility Mass Spectrometry and Electron Capture Dissociation (ECD) in conjunction with Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR-MS). Candidate conformations are modelled using the AMBER force field. Single amino acid changes, for example Gly6 --> Ala6, or Ala6 --> D-Ala6, have observable effects on the gas phase structure of GnRH. It has been shown that evolutionary primary sequence variations are key to the biological activity of GnRH, and it is thought that this is due to different binding affinities at target receptors. This work provides strong evidence that this activity is structurally based. The second system examined is the relationship between the quaternary structure and activity of two novel [beta]-defensins. FT-ICR mass spectrometry has been employed to characterize di-sulphide bridging and dissociation based experiments utilised to

  8. Contaminated Materials and Groundwater Investigation Work Plan, Chaska Flood Control Project Stages 3 and 4, Chaska, Minnesota: MPCA Phase II Investigation Work Plan

    National Research Council Canada - National Science Library

    1992-01-01

    This Phase II Investigation Work Plan discusses the field work and laboratory testing required to determine the extent of contaminated materials to be encountered during the construction of Stage 4...

  9. Absolute standard hydrogen electrode potential measured by reduction of aqueous nanodrops in the gas phase.

    Science.gov (United States)

    Donald, William A; Leib, Ryan D; O'Brien, Jeremy T; Bush, Matthew F; Williams, Evan R

    2008-03-19

    In solution, half-cell potentials are measured relative to those of other half cells, thereby establishing a ladder of thermochemical values that are referenced to the standard hydrogen electrode (SHE), which is arbitrarily assigned a value of exactly 0 V. Although there has been considerable interest in, and efforts toward, establishing an absolute electrochemical half-cell potential in solution, there is no general consensus regarding the best approach to obtain this value. Here, ion-electron recombination energies resulting from electron capture by gas-phase nanodrops containing individual [M(NH3)6]3+, M = Ru, Co, Os, Cr, and Ir, and Cu2+ ions are obtained from the number of water molecules that are lost from the reduced precursors. These experimental data combined with nanodrop solvation energies estimated from Born theory and solution-phase entropies estimated from limited experimental data provide absolute reduction energies for these redox couples in bulk aqueous solution. A key advantage of this approach is that solvent effects well past two solvent shells, that are difficult to model accurately, are included in these experimental measurements. By evaluating these data relative to known solution-phase reduction potentials, an absolute value for the SHE of 4.2 +/- 0.4 V versus a free electron is obtained. Although not achieved here, the uncertainty of this method could potentially be reduced to below 0.1 V, making this an attractive method for establishing an absolute electrochemical scale that bridges solution and gas-phase redox chemistry.

  10. Bacteria and fungi inactivation by photocatalysis under UVA irradiation: liquid and gas phase.

    Science.gov (United States)

    Rodrigues-Silva, Caio; Miranda, Sandra M; Lopes, Filipe V S; Silva, Mário; Dezotti, Márcia; Silva, Adrián M T; Faria, Joaquim L; Boaventura, Rui A R; Vilar, Vítor J P; Pinto, Eugénia

    2017-03-01

    In the last decade, environmental risks associated with wastewater treatment plants (WWTPs) have become a concern in the scientific community due to the absence of specific legislation governing the occupational exposure limits (OEL) for microorganisms present in indoor air. Thus, it is necessary to develop techniques to effectively inactivate microorganisms present in the air of WWTPs facilities. In the present work, ultraviolet light A radiation was used as inactivation tool. The microbial population was not visibly reduced in the bioaerosol by ultraviolet light A (UVA) photolysis. The UVA photocatalytic process for the inactivation of microorganisms (bacteria and fungi, ATCC strains and isolates from indoor air samples of a WWTP) using titanium dioxide (TiO 2 P25) and zinc oxide (ZnO) was tested in both liquid-phase and airborne conditions. In the slurry conditions at liquid phase, P25 showed a better performance in inactivation. For this reason, gas-phase assays were performed in a tubular photoreactor packed with cellulose acetate monolithic structures coated with P25. The survival rate of microorganisms under study decreased with the catalyst load and the UVA exposure time. Inactivation of fungi was slower than resistant bacteria, followed by Gram-positive bacteria and Gram-negative bacteria. Graphical abstract Inactivation of fungi and bacteria in gas phase by photocatalitic process performed in a tubular photoreactor packed with cellulose acetate monolith structures coated with TiO 2 .

  11. Probing Vitamine C, Aspirin and Paracetamol in the Gas Phase: High Resolution Rotational Studies

    Science.gov (United States)

    Mata, S.; Cabezas, C.; Varela, M.; Pena, I.; Nino, A.; López, J. C.; Alonso, J. L.; Grabow, J.-U.

    2011-06-01

    A solid sample of Vitamin C (m.p. 190°C) vaporized by laser ablation has been investigated in gas phase and characterized through their rotational spectra. Two spectroscopy techniques has been used to obtain the spectra: a new design of broadband chirped pulse Fourier transform microwave spectroscopy with in-phase/quadrature-phase-modulation passage-acquired-coherence technique (IMPACT) and conventional laser ablation molecular beam Fourier transform microwave spectroscopy (LA-MB-FTMW). Up to now, two low-energy conformer have been observed and their rotational constants determined. Ab initio calculations at the MP2/6-311++G (d,p) level of theory predicted rotational constants which helped us to identify these conformers unequivocally. Among the molecules to benefit from the LA-MB-FTMW technique there are common important drugs never observed in the gas phase through rotational spectroscopy. We present here the results on acetyl salicylic acid and acetaminophen (m.p. 136°C), commonly known as aspirin and paracetamol respectively. We have observed two stable conformers of aspirin and two for paracetamol. The internal rotation barrier of the methyl group in aspirin has been determined for both conformers from the analysis of the A-E splittings due to the coupling of internal and overall rotation. J. L. Alonso, C. Pérez, M. E. Sanz, J. C. López, S. Blanco, Phys. Chem. Chem. Phys. 11,617-627 (2009)and references therein

  12. Nucleation and dissociation of nano-particles in gas phase; Nucleation et evaporation de nanoparticules en phase gazeuse

    Energy Technology Data Exchange (ETDEWEB)

    Feiden, P

    2007-09-15

    This work deals with the study of nano-particles formation in gas phase and their dissociation pathways after an optical excitation. The clusters formation decomposes in two steps: a seed is formed (nucleation phase) and sticks atoms during its propagation in a sodium atomic vapor (growth phase). Those two steps have been observed separately for homogeneous Na{sub n} and heterogeneous Na{sub n}X particles (X = (NaOH){sub 2} or (Na{sub 2}O){sub 2}). The growth mechanism is well interpreted by a Monte Carlo simulation taking into account an accretion mechanism with hard-sphere cross section. The homogeneous nucleation mechanism has been highlighted by a direct comparison with the Classical Nucleation Theory predictions. The clusters fragmentation of ionic Na{sup +}(NaOH){sub p} et Na{sup +}(NaF){sub p} particles is studied in the second part. The way clusters fragment with size when they are excited optically is compared with theoretical previsions: this highlights the existence of an energetic barrier for special size of clusters. Finally, the fragmentation of doubly charged Na{sup +} Na{sup +} (NaOH){sub p} clusters shows a competition between the fission into two single charged fragments and the unimolecular evaporation of a neutral fragment. (author)

  13. The closed spiracle phase of discontinuous gas exchange predicts diving duration in the grasshopper Paracinema tricolor.

    Science.gov (United States)

    Gudowska, Agnieszka; Boardman, Leigh; Terblanche, John S

    2016-08-15

    The discontinuous gas exchange (DGE) pattern of respiration shown by many arthropods includes periods of spiracle closure (C-phase) and is largely thought to serve as a physiological adaptation to restrict water loss in terrestrial environments. One major challenge to this hypothesis is to explain the presence of DGE in insects in moist environments. Here, we show a novel ecological correlate of the C-phase, namely, diving behaviour in mesic Paracinema tricolor grasshoppers. Notably, maximal dive duration is positively correlated with C-phase length, even after accounting for mass scaling and absolute metabolic rate. Here, we propose that an additional advantage of DGE may be conferred by allowing the tracheal system to act as a sealed underwater oxygen reservoir. Spiracle closure may facilitate underwater submersion, which, in turn, may contribute to predator avoidance, the survival of accidental immersion or periodic flooding and the exploitation of underwater resources. © 2016. Published by The Company of Biologists Ltd.

  14. Gas-phase simulated moving bed: Propane/propylene separation on 13X zeolite.

    Science.gov (United States)

    Martins, Vanessa F D; Ribeiro, Ana M; Plaza, Marta G; Santos, João C; Loureiro, José M; Ferreira, Alexandre F P; Rodrigues, Alírio E

    2015-12-04

    In the last years several studies were carried out in order to separate gas mixtures by SMB technology; however, this technology has never been implemented on an industrial scale. In the present work, a gas phase SMB bench unit was built and tested for the separation of propane and propylene mixtures, using 13X zeolite extrudates as adsorbent and isobutane as desorbent. Three experiments were performed to separate propane/propylene by gas phase SMB in the bench scale unit with a 4-2-2 configuration, i.e., open loop circuit by suppressing section IV (desorbent regeneration followed by a recycle). Consequently, all the experiments were conducted using an external supply of pure isobutane as desorbent. Parameters such as switching time, extract and raffinate stream flow rates were changed to improve the efficiency of the process. Experimental results have shown that it is feasible to separate propylene from propane by gas phase SMB at a bench scale and that this process is a potential candidate to replace the conventional technologies for the propane/propylene separation. The performance parameters obtained are very promising for future development of this technology, since propylene was obtained in the extract stream with a purity of 99.93%, a recovery of 99.51%, and a productivity of [Formula: see text] . Propane was obtained in the raffinate stream with a purity of 98.10%, a recovery of 99.73% and a productivity of [Formula: see text] . The success of the above mentioned bench scale tests is a big step for the future implementation of this technology in a larger scale. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Contact line motion in confined liquid–gas systems: Slip versus phase transition

    KAUST Repository

    Xu, Xinpeng

    2010-11-30

    In two-phase flows, the interface intervening between the two fluid phases intersects the solid wall at the contact line. A classical problem in continuum fluid mechanics is the incompatibility between the moving contact line and the no-slip boundary condition, as the latter leads to a nonintegrable stress singularity. Recently, various diffuse-interface models have been proposed to explain the contact line motion using mechanisms missing from the sharp-interface treatments in fluid mechanics. In one-component two-phase (liquid–gas) systems, the contact line can move through the mass transport across the interface while in two-component (binary) fluids, the contact line can move through diffusive transport across the interface. While these mechanisms alone suffice to remove the stress singularity, the role of fluid slip at solid surface needs to be taken into account as well. In this paper, we apply the diffuse-interface modeling to the study of contact line motion in one-component liquid–gas systems, with the fluid slip fully taken into account. The dynamic van der Waals theory has been presented for one-component fluids, capable of describing the two-phase hydrodynamics involving the liquid–gas transition [A. Onuki, Phys. Rev. E 75, 036304 (2007)]. This theory assumes the local equilibrium condition at the solid surface for density and also the no-slip boundary condition for velocity. We use its hydrodynamicequations to describe the continuum hydrodynamics in the bulk region and derive the more general boundary conditions by introducing additional dissipative processes at the fluid–solid interface. The positive definiteness of entropy production rate is the guiding principle of our derivation. Numerical simulations based on a finite-difference algorithm have been carried out to investigate the dynamic effects of the newly derived boundary conditions, showing that the contact line can move through both phase transition and slip, with their relative

  16. Predicting PAH bioaccumulation and toxicity in earthworms exposed to manufactured gas plant soils with solid-phase microextraction

    Energy Technology Data Exchange (ETDEWEB)

    Michiel T.O. Jonker; Stephan A. van der Heijden; Joseph P. Kreitinger; Steven B. Hawthorne [Utrecht University, Utrecht (Netherlands). Institute for Risk Assessment Sciences

    2007-11-01

    Soils from former manufactured gas plant (MGP) sites are often heavily contaminated with polycyclic aromatic hydrocarbons (PAHs). Current risk assessment methods that rely on total PAH concentrations likely overstate adverse effects of such soils since bioavailability is ignored. In this study, solid-phase microextraction (SPME) was applied to estimate bioavailable PAH concentrations and toxicity in earthworms exposed to 15 MGP soils. In addition, PAH sorption to all soils (K{sub oc} values) was determined. The results showed a several orders of magnitude variation in K{sub oc} values, demonstrating that generic organic carbon-normalized sorption coefficients will typically be over-conservative at MGP sites. SPME-predicted bioaccumulation generally was within a factor of 10 of measured bioaccumulation (in earthworm bioassays), in contrast to current risk assessment model estimates that over predicted bioaccumulation 10-10,000 times. Furthermore, on the basis of estimated total body residues of narcotic PAHs, SPME correctly predicted worm mortality observed during bioassays in the majority of cases. For MGP sites where current risk assessment procedures indicate concerns, SPME thus provides a useful tool for performing a refined, site-specific assessment. 35 refs., 4 figs.

  17. Method development for fingerprinting of biodiesel blends by solid-phase extraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Yang, Zeyu; Hollebone, Bruce P; Wang, Zhendi; Yang, Chun; Landriault, Mike

    2011-11-01

    A method based on the combination of solid-phase extraction (SPE) with gas chromatography-mass spectrometry (GC/MS) for detailed chemical fingerprinting of biodiesel/petrodiesel blends was developed in the present study. Forensic identification, commonly referred to as chemical fingerprinting, is based on the relative distributions of individual aliphatic hydrocarbons, aromatic hydrocarbons, fatty acid alkyl esters, and free sterols. Fractionation of fuel samples is optimized for the separation of fatty acid esters and free sterols from petroleum hydrocarbons into four fractions: aliphatic, aromatic, fatty acid ester, and polar components. The final recoveries of aliphatic and aromatic hydrocarbons were determined to be in the range of 65-103%, 73-105% for FAMEs, and 78-103% for free sterols in the polar fraction. Excellent separation with negligible crossover of components with different polarities between fractions was observed. Quantitative analysis of blend levels and individual chemical distribution were achieved. The method has great potential for the identification of biodiesel in diesel fuel blends and could form the basis of a method for characterization of biodiesel-contaminated environmental samples. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Shock attenuation in two-phase (gas-liquid) jets for inertial fusion applications

    Science.gov (United States)

    Lascar, Celine C.

    Z-Pinch IFE (Inertial Fusion Energy) reactor designs will likely utilize high yield targets (˜ 3 GJ) at low repetition rates (˜ 0.1 Hz). Appropriately arranged thick liquid jets can adequately protect the cavity walls from the target X-rays, ions, and neutrons. However, the shock waves and mechanical loadings produced by rapid heating and evaporation of incompressible liquid jets may be challenging to accommodate within a small reactor cavity. This investigation examines the possibility of using two-phase compressible (liquid/gas) jets to protect the cavity walls in high yield IFE systems, thereby mitigating the mechanical consequences of rapid energy deposition within the jets. Two-phase, free, vertical jets with different cross sections (planar, circular, and annular) were examined over wide ranges of liquid velocities and void fractions. The void fraction and bubble size distributions within the jets were measured; correlations to predict variations of the slip ratio and the Sauter mean diameter were developed. An exploding wire system was used to generate a shock wave at the center of the annular jets. Attenuation of the shock by the surrounding single- or two-phase medium was measured. The results show that stable coherent jets can be established and steadily maintained over a wide range of inlet void fractions and liquid velocities, and that significant attenuation in shock strength can be attained with relatively modest void fractions (˜ 1%); the compressible two-phase jets effectively convert and dissipate mechanical energy into thermal energy within the gas bubbles. The experimental characteristics of single- and two-phase jets were compared against predictions of a state-of-art CFD code (FLUENTRTM ). The data obtained in this investigation will allow reactor system designers to predict the behavior of single- and two-phase jets and quantify their effectiveness in mitigating the consequences of shock waves on the cavity walls in high yield IFE systems.

  19. The phase equilibria of multicomponent gas hydrate in methanol/ethylene glycol solution based formation water

    International Nuclear Information System (INIS)

    Xu, Shurui; Fan, Shuanshi; Yao, Haiyuan; Wang, Yanhong; Lang, Xuemei; Lv, Pingping; Fang, Songtian

    2017-01-01

    Highlights: • The equilibrium data in THI solution based formation water is first investigated. • The 0.55 mass fraction concentration of EG 0.55 mass fraction fills the vacancy of this area. • The testing pressure range from 4.22 MPa to 34.72 MPa was rare in published data. - Abstract: In this paper, the three-phase coexistence points are generated for multicomponent gas hydrate in methanol (MeOH) solution for (0.05, 0.10, 0.15, and 0.35) mass fraction and ethylene glycol (EG) solution for (0.05, 0.10, 0.15, 0.35, 0.40 and 0.55) mass fraction. The phase equilibrium curves of different system were obtained by an isochoric pressure-search method on high pressure apparatus. The phase equilibrium regions of multicomponent gas hydrate were measured using the same composition of natural gas distributed in the South China Sea. And the different concentration solutions were prepared based formation water. The experimental data were measured in a wide range temperature from 267.74 to 298.53 K and a wide range pressure from 4.22 MPa to 34.72 MPa. The results showed that the hydrate phase equilibrium curves shifted to the inhibition region in accordance with the increased inhibitor concentration. In addition, the equilibrium temperature would decrease about 2.7 K when the concentration of MeOH increased 0.05 mass fraction. Besides, the suppression temperature was 1.25 K with the 0.05 mass fraction increase of EG concentration in the range of 0.05 mass fraction to 0.15 mass fraction. While in high EG concentration region, the suppression temperature was 3.3 K with the same increase of EG concentration (0.05 mass fraction).

  20. Assessment of Soil-Gas, Surface-Water, and Soil Contamination at the Installation Railhead, Fort Gordon, Georgia, 2008-2009

    Science.gov (United States)

    Landmeyer, James E.; Harrelson, Larry G.; Ratliff, W. Hagan; Wellborn, John B.

    2010-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of the Army Environmental and Natural Resources Management Office of the U.S. Army Signal Center and Fort Gordon, assessed soil gas, surface water, and soil for contaminants at the Installation Railhead (IR) at Fort Gordon, Georgia, from October 2008 to September 2009. The assessment included delineation of organic contaminants present in soil-gas samples beneath the IR, and in a surface-water sample collected from an unnamed tributary to Marcum Branch in the western part of the IR. Inorganic contaminants were determined in a surface-water sample and in soil samples. This assessment was conducted to provide environmental contamination data to Fort Gordon personnel pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Soil-gas samples collected within a localized area on the western part of the IR contained total petroleum hydrocarbons; benzene, toluene, ethylbenzene, and total xylenes (referred to as BTEX); and naphthalene above the method detection level. These soil-gas samples were collected where buildings had previously stood. Soil-gas samples collected within a localized area contained perchloroethylene (PCE). These samples were collected where buildings 2410 and 2405 had been. Chloroform and toluene were detected in a surface-water sample collected from an unnamed tributary to Marcum Branch but at concentrations below the National Primary Drinking Water Standard maximum contaminant level (MCL) for each compound. Iron was detected in the surface-water sample at 686 micrograms per liter (ug/L) and exceeded the National Secondary Drinking Water Standard MCL for iron. Metal concentrations in composite soil samples collected at three locations from land surface to a depth of 6 inches did not exceed the U.S. Environmental Protection Agency Regional Screening Levels for industrial soil.

  1. ART CCIM Phase II-A Off-Gas System Evaluation Test Plan

    Energy Technology Data Exchange (ETDEWEB)

    Nick Soelberg; Jay Roach

    2009-01-01

    This test plan defines testing to be performed using the Idaho National Laboratory (INL) engineering-scale cold crucible induction melter (CCIM) test system for Phase II-A of the Advanced Remediation Technologies (ART) CCIM Project. The multi-phase ART-CCIM Project is developing a conceptual design for replacing the joule-heated melter (JHM) used to treat high level waste (HLW) in the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) with a cold crucible induction melter. The INL CCIM test system includes all feed, melter off-gas control, and process control subsystems needed for fully integrated operation and testing. Testing will include operation of the melter system while feeding a non-radioactive slurry mixture prepared to simulate the same type of waste feed presently being processed in the DWPF. Process monitoring and sample collection and analysis will be used to characterize the off-gas composition and properties, and to show the fate of feed constituents, to provide data that shows how the CCIM retrofit conceptual design can operate with the existing DWPF off-gas control system.

  2. Aromatic substitution in the gas phase. Alkylation of arenes by gaseous C4H9+ cations

    International Nuclear Information System (INIS)

    Cacace, F.; Ciranni, G.; Giacomello, P.

    1981-01-01

    Butyl cations, obtained in the dilute gas state from the radiolysis of butane in the pressure range from 70 to 750 torr, have been allowed to react with benzene, toluene, and their mixtures or with trace amounts of o-xylene in the gaseous system. The gas-phase butylation yields invariably sec-butylarenes, remarkably free of isomeric byproducts, namely n- and tert-butylarenes. Other alkylation experiments, where gaseous butyl cations from the reaction of butane with radiolytically formed H 3 + ions were used as reagent, confirmed the exclusive formation of sec-butylarenes. The butylation process displays the positional and substrate selectivity and the dependence of orientation on the pressure of the system, typical of other gas-phase ionic substitutions. At high pressures, orth-para orientation predominates in the sec-butylation of toluene, with a ortho:meta:para ratio of 43:30:27 at 715 torr. As the pressure is reduced, a gradual shift in favor of the thermodynamically most stable meta-substituted arenium ion is observed, leading to a ortho:meta:para ratio of 31:48:21 at 70 torr

  3. Biofiltration of mixtures of gas-phase styrene and acetone with the fungus Sporothrix variecibatus

    Energy Technology Data Exchange (ETDEWEB)

    Rene, Eldon R.; Spackova, Radka; Veiga, Maria C. [University of La Coruna, Dpt. of Chemical Engineering, Campus da Zapateira, Rua da Fraga, 10, 15008 La Coruna (Spain); Kennes, Christian, E-mail: kennes@udc.es [University of La Coruna, Dpt. of Chemical Engineering, Campus da Zapateira, Rua da Fraga, 10, 15008 La Coruna (Spain)

    2010-12-15

    The biodegradation performance of a biofilter, inoculated with the fungus Sporothrix variecibatus, to treat gas-phase styrene and acetone mixtures under steady-state and transient conditions was evaluated. Experiments were carried out by varying the gas-flow rates (0.05-0.4 m{sup 3} h{sup -1}), leading to empty bed residence times as low as 17.1 s, and by changing the concentrations of gas-phase styrene (0.01-6.3 g m{sup -3}) and acetone (0.01-8.9 g m{sup -3}). The total elimination capacities were as high as 360 g m{sup -3} h{sup -1}, with nearly 97.5% removal of styrene and 75.6% for acetone. The biodegradation of acetone was inhibited by the presence of styrene, while styrene removal was affected only slightly by the presence of acetone. During transient-state experiments, increasing the overall pollutant load by almost 3-fold, i.e., from 220 to 600 g m{sup -3} h{sup -1}, resulted in a sudden drop of removal efficiency (>90-70%), but still high elimination capacities were maintained. Periodic microscopic observations revealed that the originally inoculated Sporothrix sp. remained present in the reactor and actively dominant in the biofilm.

  4. Gas-Phase Photolysis of Pyruvic Acid: The Effect of Pressure on Reaction Rates and Products.

    Science.gov (United States)

    Reed Harris, Allison E; Doussin, Jean-Francois; Carpenter, Barry K; Vaida, Veronica

    2016-12-29

    In this work, we investigate the impact of pressure and oxygen on the kinetics of and products from the gas-phase photolysis of pyruvic acid. The results reveal a decrease in the photolysis quantum yield as pressure of air or nitrogen is increased, a trend not yet documented in the literature. A Stern-Volmer analysis demonstrates this effect is due to deactivation of the singlet state of pyruvic acid when the photolysis is performed in nitrogen, and from quenching of both the singlet and triplet state in air. Consistent with previous studies, acetaldehyde and CO 2 are observed as the major products; however, other products, most notably acetic acid, are also identified in this work. The yield of acetic acid increases with increasing pressure of buffer gas, an effect that is amplified by the presence of oxygen. At least two mechanisms are necessary to explain the acetic acid, including one that requires reaction of photolysis intermediates with O 2 . These findings extend the fundamental understanding of the gas-phase photochemistry of pyruvic acid, highlighting the importance of pressure on the photolysis quantum yields and products.

  5. NON-INTRUSIVE GAS-PHASE THERMOMETRY FOR INDUSTRIAL OXY-FUEL BURNERS

    Directory of Open Access Journals (Sweden)

    J. W. Tröger

    2015-03-01

    Full Text Available The use of oxy-fuel combustion processes is of large interest for several industrial fields applications since it offers the advantages of low NOx emissions in combination with high combustion temperatures even without additional preheating. For optimization of such processеs a detailed understanding based on precise experimental data is necessary. So far there is still a lack of precise experimental data achieved with high spatial and temporal resolution from industrial relevant turbulent oxy-fuel combustion processes. Beside species concentration information the gas phase temperature is of utmost importance for an improved understanding of the basic chemical reactions and the pollutant formation. The coherent anti-Stokes Raman spectroscopy (CARS technique is a very well suited laser based tool for a non-intrusive investigation of such turbulent high temperature combustion processes. In this work we analysed an industrial 400 kW oxy-fuel burner with the help of O2 based vibrational CARS system which is integrated in an industrial relevant test furnace. The burner is fed with pure oxygen and natural gas at an equivalence ratio of =0.9. At one downstream position temporal and spatial resolved temperatures were measured along a 600 mm line. Additional air sucked in from the environment seems to influence the gas phase temperature significantly.

  6. Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility

    Science.gov (United States)

    2012-05-01

    dialysis 40 , gas purging 41 , alum flocculation to remove colloids 42 , and passive samplers such as semipermeable membranes (SPMD)43, Empore disks44...the particles. Samples were equilibrated overnight, after which an aliquot of the extract was separated , blown down with nitrogen gas using a...as the lipid-water partition coefficient. 112 transparent core tubing of cellulose acetate butyrate or Eastman Tenite Butyrate with a 6.67-cm

  7. Coupled LBM-DEM Three-phase Simulation on Gas Flux Seeping from Marine Sediment

    Science.gov (United States)

    Kano, Y.; Sato, T.

    2014-12-01

    One of the main issues of the geological storage of CO2 under the seabed is a risk of CO2 leakage. Once CO2seeps into the ocean, it rises in water column dissolving into seawater, which results in the acidification of seawater and/or returning to the air. Its behaviour significantly depends on flow rate and bubble size (Kano et al., 2009; Dewar et al., 2013). As for porous media, bubble size is generally predicted through simple force balance based on flow rate, surface tension and channel size which is estimated by porosity and grain size. However, in shallow marine sediments, grains could be mobilised and displaced by buoyant gas flow, which causes distinctive phenomena such as blow-out or formation of gas flow conduit. As a result, effective gas flux into seawater can be intermissive, and/or concentrated in narrow area (QICS, 2012; Kawada, 2013). Bubble size is also affected by these phenomena. To predict effective gas flux and bubble size into seawater, three-phase behaviour of gas-water-sediment grains should be revealed. In this presentation, we will report the results of gas-liquid-solid three-phase simulations and their comparisons with experimental and observation data. Size of solid particles is based on grain size composing marine sediments at some CCS project sites. Fluid-particle interactions are solved using the lattice Boltzmann method (LBM), while the particle-particle interactions are treated by coupling with the Discrete Element method (DEM). References: Dewar, M., Wei, W., McNeil, D., Chen, B., 2013. Small-scale modelling of the physiochemical impacts of CO2leaked from sub-seabed reservoirs or pipelines within the North Sea and surrounding waters. Marine Pollution Bulletin 73(2), 504-515. Kano, Y., Sato, T., Kita, J., Hirabayashi, S., Tabeta, S., 2009. Model prediction on the rise of pCO2 in uniform flows by leakage of CO2purposefully stored under the seabed. Int. J. Greenhouse Gas Control, Vol. 3(5), 617-625. Kawada, R. 2014. A study on the

  8. Colorado Water Watch: real-time groundwater monitoring for possible contamination from oil and gas activities.

    Science.gov (United States)

    Son, Ji-Hee; Hanif, Asma; Dhanasekar, Ashwin; Carlson, Kenneth H

    2018-02-13

    Currently, only a few states in the USA (e.g., Colorado and Ohio) require mandatory baseline groundwater sampling from nearby groundwater wells prior to drilling a new oil or gas well. Colorado is the first state to regulate groundwater testing before and after drilling, which requires one pre-drilling sample and two additional post-drilling samples within 6-12 months and 5-6 years of drilling. However, the monitoring method is limited to the state's regulatory agency and to ex situ sampling, which offers only a snapshot in time. To overcome the limitations and increase monitoring performance, a new groundwater monitoring system, Colorado Water Watch (CWW), was introduced as a decision-making tool to support the state's regulatory agency and also to provide real-time groundwater quality data to both the industry and the public. The CWW uses simple in situ water quality sensors based on the surrogate sensing technology that employs an event detection system to screen the incoming data in near real-time.

  9. Hydrodynamic characteristics of a two-phase gas-liquid flow upward through a fixed bed of spherical particles

    Directory of Open Access Journals (Sweden)

    VELIZAR D. STANKOVIC

    2001-01-01

    Full Text Available The influence of an electrochemically generated gas phase on the hydrodynamic characteristics of a three-phase system has been examined. The two-phase fluid, (gas-liquid, in which the liquid phase is the continuous one, flows through a packed bed with glass spheres. The influence of the liquid velocity was examined, as well as the gas velocity and particle diameter on the pressure drop through the fixed bed. It was found that with increasing liquid velocity (wl = 0.0162–0.03 m/s, the relative pressure drop decreases through the fixed bed. With increasing current density, the pressure drop increases, since greater gas quantities stay behind in the fixed bed. Besides, it was found that with decreasing diameter of the glass particles, the relative pressure drop also decreases. The relationship betweeen the experimentally obtained friction factor and the Reynolds number was established.

  10. Evaporation and Condensation Flows of a Vapor-Gas Mixture from or onto the Condensed Phase with an Internal Structure

    National Research Council Canada - National Science Library

    Onishi, Yoshimoto; Yamada, Ken

    2005-01-01

    Transient motions of a vapor-gas mixture due to the evaporation and condensation processes from or onto the plane condensed phase, with a temperature field as its internal structure, have been studied...

  11. Velocity field measurement in gas-liquid metal two-phase flow with use of PIV and neutron radiography techniques

    International Nuclear Information System (INIS)

    Saito, Y.; Mishima, K.; Tobita, Y.; Suzuki, T.; Matsubayashi, M.

    2001-01-01

    Neutron radiography and PIV (Particle Image Velocimetry) techniques were applied to measurements of velocity field in gas-liquid metal two-phase flow. Visualization and measurements of two-phase flow were conducted using molten lead bismuth and nitrogen gas as working fluids and particles made of gold-cadmium (AuCd 3 ) inter-metallic alloy were employed as the tracer. Discrimination method between bubble and tracer images in two-phase flow was developed based on the σ-scaling method. Time-averaged liquid velocity fields, gas velocity fields and void profile were calculated from discriminated images, respectively. From these measurements, the basic characteristics of gas-liquid metal two-phase mixture were clarified. (author)

  12. Modeling of gas-phase chemistry in the chemical vapor deposition of polysilicon in a cold wall system

    Energy Technology Data Exchange (ETDEWEB)

    Toprac, A.J.; Edgar, T.F.; Trachtenberg, I. (Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering)

    1993-06-01

    The relative contribution of gas-phase chemistry to deposition processes is an important issue both from the standpoint of operation and modeling of these processes. In polysilicon deposition from thermally activated silane in a cold wall rapid thermal chemical vapor deposition (RTCVD) system, the relative contribution of gas-phase chemistry to the overall deposition rate was examined by a mass-balance model. Evaluating the process at conditions examined experimentally, the model indicated that gas-phase reactions may be neglected to good accuracy in predicting polysilicon deposition rate. The model also provided estimates of the level of gas-phase generated SiH[sub 2] associated with deposition on the cold-process chamber walls.

  13. Simultaneous measurements of formaldehyde and nitrous acid in dews and gas phase in the atmosphere of Santiago, Chile

    Science.gov (United States)

    Rubio, María A.; Lissi, Eduardo; Villena, Guillermo; Elshorbany, Y. F.; Kleffmann, Jörg; Kurtenbach, Ralf; Wiesen, Peter

    2009-12-01

    The amounts of formaldehyde and nitrous acid (HONO) in gas phase and dews of Santiago de Chile were simultaneously measured. Formaldehyde concentrations values in the liquid phase (dews) correlate fairly well with those in the gaseous phase and are even higher than those expected from gas-dew equilibrium. On the other hand, nitrite concentrations in dews were considerably smaller (ca. 15 times) than those expected from the gas-phase concentrations. This under-saturation is attributed to diffusion limitations due to the relatively large HONO solubility. In agreement with this, under-saturation increases with the rate of dew formation and the pH of the collected waters, factors that should increase the rate of gas to liquid HONO transfer required to reach equilibrium.

  14. Development of a remediation strategy for surface soils contaminated with energetic materials by thermal processes: Phases 1, 2 and 3

    Science.gov (United States)

    2009-11-01

    carburants (liquides et gels) pourrait être utilisée comme méthode de restauration pour effectuer la décomposition thermique des résidus de poudres...restauration de sols contaminés par les matériaux énergétiques pourrait être faite en utilisant un procédé thermique qui implique la combustion d’un gel à base...improve the design of the burn to increase the transfer of heat to the soil profile. 8 DRDC Valcartier TR 2009-150 3 Phase 1 : Preliminary

  15. X-ray phase contrast with injected gas for tumor microangiography

    International Nuclear Information System (INIS)

    Lundström, U; Larsson, D H; Burvall, A; Hertz, H M; Westermark, U K; Henriksson, M Arsenian

    2014-01-01

    We show that the microvasculature of mouse tumors can be visualized using propagation-based phase-contrast x-ray imaging with gas as the contrast agent. The large density difference over the gas–tissue interface provides high contrast, allowing the imaging of small-diameter blood vessels with relatively short exposure times and low dose using a compact liquid-metal-jet x-ray source. The method investigated is applied to tumors (E1A/Ras-transformed mouse embryonic fibroblasts) grown in mouse ears, demonstrating sub-15-µm-diameter imaging of their blood vessels. The exposure time for a 2D projection image is a few seconds and a full tomographic 3D map takes some minutes. The method relies on the strength of the vasculature to withstand the gas pressure. Given that tumor vessels are known to be more fragile than normal vessels, we investigate the tolerance of the vasculature of 12 tumors to gas injection and find that a majority withstand 200 mbar pressures, enough to fill 12-µm-diameter vessels with gas. A comparison of the elasticity of tumorous and non-tumorous vessels supports the assumption of tumor vessels being more fragile. Finally, we conclude that the method has the potential to be extended to the imaging of 15 µm vessels in thick tissue, including mouse imaging, making it of interest for, e.g., angiogenesis research. (paper)

  16. Third-order gas-liquid phase transition and the nature of Andrews critical point

    Directory of Open Access Journals (Sweden)

    Tian Ma

    2011-12-01

    Full Text Available The main objective of this article is to study the nature of the Andrews critical point in the gas-liquid transition in a physical-vapor transport (PVT system. A dynamical model, consistent with the van der Waals equation near the Andrews critical point, is derived. With this model, we deduce two physical parameters, which interact exactly at the Andrews critical point, and which dictate the dynamic transition behavior near the Andrews critical point. In particular, it is shown that 1 the gas-liquid co-existence curve can be extended beyond the Andrews critical point, and 2 the transition is first order before the critical point, second-order at the critical point, and third order beyond the Andrews critical point. This clearly explains why it is hard to observe the gas-liquid phase transition beyond the Andrews critical point. Furthermore, the analysis leads naturally the introduction of a general asymmetry principle of fluctuations and the preferred transition mechanism for a thermodynamic system. The theoretical results derived in this article are in agreement with the experimental results obtained in (K. Nishikawa and T. Morita, Fluid behavior at supercritical states studied by small-angle X-ray scattering, Journal of Supercritical Fluid, 13 (1998, pp. 143-148. Also, the derived second-order transition at the critical point is consistent with the result obtained in (M. Fisher, Specific heat of a gas near the critical point, Physical Review, 136:6A (1964, pp. A1599-A1604.

  17. Femtosecond time-resolved studies of coherent vibrational Raman scattering in large gas-phase molecules

    International Nuclear Information System (INIS)

    Hayden, C.C.; Chandler, D.W.

    1995-01-01

    Results are presented from femtosecond time-resolved coherent Raman experiments in which we excite and monitor vibrational coherence in gas-phase samples of benzene and 1,3,5-hexatriene. Different physical mechanisms for coherence decay are seen in these two molecules. In benzene, where the Raman polarizability is largely isotropic, the Q branch of the vibrational Raman spectrum is the primary feature excited. Molecules in different rotational states have different Q-branch transition frequencies due to vibration--rotation interaction. Thus, the macroscopic polarization that is observed in these experiments decays because it has many frequency components from molecules in different rotational states, and these frequency components go out of phase with each other. In 1,3,5-hexatriene, the Raman excitation produces molecules in a coherent superposition of rotational states, through (O, P, R, and S branch) transitions that are strong due to the large anisotropy of the Raman polarizability. The coherent superposition of rotational states corresponds to initially spatially oriented, vibrationally excited, molecules that are freely rotating. The rotation of molecules away from the initial orientation is primarily responsible for the coherence decay in this case. These experiments produce large (∼10% efficiency) Raman shifted signals with modest excitation pulse energies (10 μJ) demonstrating the feasibility of this approach for a variety of gas phase studies. copyright 1995 American Institute of Physics

  18. Land application uses for dry flue gas desulfurization by-products: Phase 3

    Energy Technology Data Exchange (ETDEWEB)

    Dick, W.; Bigham, J.; Forster, R.; Hitzhusen, F.; Lal, R.; Stehouwer, R.; Traina, S.; Wolfe, W.; Haefner, R.; Rowe, G.

    1999-01-31

    New flue gas desulfurization (FGD) scrubbing technologies create a dry, solid by-product material consisting of excess sorbent, reaction product that contains sulfate and sulfite, and coal fly ash. Generally, dry FGD by-products are treated as solid wastes and disposed in landfills. However, landfill sites are becoming scarce and tipping fees are constantly increasing. Provided the environmental impacts are socially and scientifically acceptable, beneficial uses via recycling can provide economic benefits to both the producer and the end user of the FGD. A study titled ''Land Application Uses for Dry Flue Gas Desulfurization By-Products'' was initiated in December, 1990 to develop and demonstrate large volume, beneficial uses of FGD by-products. Phase 1 and Phase 2 reports have been published by the Electric Power Research Institute (EPRI), Palo Alto, CA. Phase 3 objectives were to demonstrate, using field studies, the beneficial uses of FGD by-products (1) as an amendment material on agricultural lands and on abandoned surface coal mine land, (2) as an engineering material for soil stabilization and raid repair, and (3) to assess the environmental and economic impacts of such beneficial uses. Application of dry FGD by-product to three soils in place of agricultural limestone increased alfalfa (Medicago sativa L.) and corn (Zea may L.) yields. No detrimental effects on soil and plant quality were observed.

  19. Molecular dynamics simulation of gas-phase ozone reactions with sabinene and benzene.

    Science.gov (United States)

    Ridgway, H F; Mohan, B; Cui, X; Chua, K J; Islam, M R

    2017-06-01

    Gas-phase reactions of ozone (O 3 ) with volatile organic compounds were investigated both by experiment and molecular simulations. From our experiments, it was found ozone readily reacts with VOC pure components and reduces it effectively. By introducing ozone intermittently, the reaction between VOC and ozone is markedly enhanced. In order to understand the relationship between intermediate reactions and end products, ozone reaction with benzene and alicyclic monoterpene sabinene were simulated via a novel hybrid quantum mechanical/molecular mechanics (QM/MM) algorithm that forced repeated bimolecular collisions. Molecular orbital (MO) rearrangements (manifested as bond dissociation or formation), resulting from the collisions, were computed by semi-empirical unrestricted Hartree-Fock methods (e.g., RM1). A minimum of 975 collisions between ozone and targeted organic species were performed to generate a distribution of reaction products. Results indicated that benzene and sabinene reacted with ozone to produce a range of stable products and intermediates, including carbocations, ring-scission products, as well as peroxy (HO 2 and HO 3 ) and hydroxyl (OH) radicals. Among the stable sabinene products observed included formaldehyde and sabina-ketone, which have been experimentally demonstrated in gas-phase ozonation reactions. Among the benzene ozonation products detected composed of oxygen mono-substituted aromatic C 6 H 5 O, which may undergo further transformation or rearrangement to phenol, benzene oxide or 2,4-cyclohexadienone; a phenomenon which has been experimentally observed in vapor-phase photocatalytic ozonation reactions. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Applying ion-molecule reactions to studies of gas-phase protein structure

    Energy Technology Data Exchange (ETDEWEB)

    Ogorzalek Loo, R.R.; Loo, J.A.; Smith, R.D.

    1992-06-01

    Whether solution phase differences in protein higher order structure persist in the gas phase, is examined by means of proton transfer reactions on ions generated by electrospray ionization of different solution conformations. Ion-molecule reactions were carried out in the atmosphere-vacuum interface of a quadrupole mass spectrometer with a Y-shaped capillary inlet-reactor. An amine (dimethyl-, trimethyl-, or diethyl-) were delivered to one inlet arm. Reactivities of bovine cytochrome c ions sprayed from denatured and native solutions were determined; the ions generated shifted to about the same charge states. Addition of equal amounts of amine to ions generated from different solution conformations of bovine ubiquitin also yielded similar final charge states; however, the average charge state increased with temperature. Myoglobin and apomyoglobin also yielded similar final charge states. The results suggest that for the non-disulfide linked proteins, either there are not significant differences in gas phase higher order structure, or proton transfer reactions are not sensitive enough to detect higher order structural differences arising from noncovalent interactions. 2 refs, 2 figs. (DLC)

  1. Gas phase emitter effect of thulium within ceramic metal halide lamps in dependence on frequency

    Energy Technology Data Exchange (ETDEWEB)

    Ruhrmann, C.; Depta, M.; Bergner, A.; Hoebing, T.; Mentel, J.; Awakowicz, P. [Ruhr University Bochum, Electrical Engineering and Plasma Technology, D-44780 Bochum (Germany); Denissen, C.; Suijker, J. [Philips Lighting, Category Prof. Lamps, PO Box 80020, NL-5600JM Eindhoven (Netherlands)

    2014-02-15

    The gas phase emitter effect within ceramic metal halide (CMH) lamps reduces the effective work function of the electrode material and, therewith, the electrode temperature. An investigation of the gas phase emitter effect of thulium (Tm) within CMH lamps seeded with Tm iodide (TmI3) is carried out. For this purpose, phase resolved images of the arc attachment and measurements of the electrode temperature, Tm atom and ion densities are performed in dependence on operating frequency by pyrometry and optical emission spectroscopy. Additionally, the influence of a sodium iodide (NaI) admixture is studied. The emitter effect is generated by means of a monolayer of Tm atoms on the electrode surface generated by a Tm ion current within the cathodic phase. It overlaps onto the anodic phase at higher frequencies of some hundreds of hertz. The reason is the finite life time of the monolayer, which is determined by the adsorption energy of Tm on the tungsten surface. Due to the low electric field strength in front of the anode and the mass inertia, the emitter ions and atoms remain in front of the anode. They retard the decay of the monolayer and with it the increase of the work function. Moreover, a comparison of a lamp seeded with TmI3 and sodium iodide (NaI) with a lamp seeded only with TmI3 illustrates a slight reduction of the electrode tip temperature caused by a higher Tm saturation vapour pressure and a higher Tm amount within the lamp filling. The influence of Na appears to be quite low. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Ethylene epoxidation promoted by methane gas-phase thermic oxidation. The influence of temperature

    International Nuclear Information System (INIS)

    Grigoryan, R.R.; Arsentiev, S.D.; Mantashyan, A.A.

    2009-01-01

    Ethylene epoxidation promoted by methane gas-phase thermic oxidation has been studied. The studies were carried out in a two-sectional reactor under flow conditions. The experiments were performed in different temperatures in the sections of the reactor. It was shown that when methane is oxidized in the first section of the reactor and ethylene is put into the second section, epoxidation of olefin occurs through the alkyl peroxy radical interaction with double bond of olefin. It was established that the dependences of epoxidation rate on temperatures in both first and second sections pass trough maximum. The substitution of methane with inert gas (argon) in the first section leads to significant decrease of rate of ethylene oxide accumulation in the second section

  3. Gas-Phase Photochemical Overall H2S Splitting by UV Light Irradiation.

    Science.gov (United States)

    Baldovi, Herme G; Albero, Josep; Ferrer, Belen; Mateo, Diego; Alvaro, Mercedes; García, Hermenegildo

    2017-05-09

    Splitting of hydrogen sulfide is achieved to produce value-added chemicals. Upon irradiation at 254 nm in the gas phase and in the absence of catalysts or photocatalysts at near room temperature, H 2 S splits into stoichiometric amounts of H 2 and S with a quantum efficiency close to 50 %. No influence of the presence of CH 4 and CO 2 (typical components in natural gas and biogas in which H 2 S is an unwanted component) on the efficiency of overall H 2 S splitting was observed. A mechanism for the H 2 and S formation is proposed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Modeling of a three-phase reactor for bitumen-derived gas oil hydrotreating

    Directory of Open Access Journals (Sweden)

    R. Chacón

    2012-03-01

    Full Text Available A three-phase reactor model for describing the hydrotreating reactions of bitumen-derived gas oil was developed. The model incorporates the mass-transfer resistance at the gas-liquid and liquid-solid interfaces and a kinetic rate expression based on a Langmuir-Hinshelwood-type model. We derived three correlations for determining the solubility of hydrogen (H2, hydrogen sulfide (H2S and ammonia (NH3 in hydrocarbon mixtures and the calculation of the catalyst effectiveness factor was included. Experimental data taken from the literature were used to determine the kinetic parameters (stoichiometric coefficients, reaction orders, reaction rate and adsorption constants for hydrodesulfuration (HDS and hydrodenitrogenation (HDN and to validate the model under various operating conditions. Finally, we studied the effect of operating conditions such as pressure, temperature, LHSV, H2/feed ratio and the inhibiting effect of H2S on HDS and NH3 on HDN.

  5. Gas phase chemistry and removal of CH{sub 3}I during a severe accident

    Energy Technology Data Exchange (ETDEWEB)

    Karhu, A. [VTT. Energy, Esbo (Finland)

    2001-01-01

    The purpose of this literature review was to gather valuable information on the behavior of methyl iodide on the gas phase during a severe accident. The potential of transition metals, especially silver and copper, to remove organic iodides from the gas streams was also studied. Transition metals are one of the most interesting groups in the context of iodine mitigation. For example silver is known to react intensively with iodine compounds. Silver is also relatively inert material and it is thermally stable. Copper is known to react with some radioiodine species. However, it is not reactive toward methyl iodide. In addition, it is oxidized to copper oxide under atmospheric conditions. This may limit the industrial use of copper.(au)

  6. A compressed hydrogen gas storage system with an integrated phase change material

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rothuizen, Erasmus Damgaard; Jørgensen, Jens Erik

    2015-01-01

    change material, mainly occurs after the fueling is completed, resulting in a higher hydrogen peak temperature inside the tank and a lower fuelled mass than a gas-cooled system. Such a mass reduction accounts for 12% with respect to the case of a standard tank system fuelled at -40 °C.......A dynamic fueling model is built to simulate the fueling process of a hydrogen tank with an integrated passive cooling system. The study investigates the possibility of absorbing a part of the heat of compression in the high latent-heat material during melting, with the aim of keeping the walls...... below the critical temperature of 85 °C, while filling the hydrogen at ambient temperature. Results show that a 10-mm-thick layer of paraffin wax can absorb enough heat to reduce the adiabatic temperature by 20 K when compared to a standard Type IV tank. The heat transfer from the gas to the phase...

  7. Oxidation of elemental mercury by chlorine: Gas phase, Surface,and Photo-induced reaction pathways

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Nai-Qiang; Liu, Shou-Heng; Chang, Shih-Ger

    2004-10-22

    Accurate oxidation rate constants of mercury gas are needed for determining its dispersion and lifetime in the atmosphere. They would also help in developing a technology for the control of mercury emissions from coal-fired power plants. However, it is difficult to establish the accurate rate constants primarily due to the fact that mercury easily adsorbs on solid surface and its reactions can be catalyzed by the surface. We have demonstrated a procedure that allows the determination of gas phase, surface-induced, and photo-induced contributions in the kinetic study of the oxidation of mercury by chlorine gas. The kinetics was studied using reactors with various surface to volume ratios. The effect of the surface and the photo irradiation on the reaction was taken into consideration. The pressure dependent study revealed that the gas phase oxidation was a three-body collision process. The third order rate constant was determined to be 7.5({+-}0.2) x 10{sup -39} mL{sup 2} molecules{sup -2}s{sup -1} with N{sub 2} as the third body at 297 {+-} 1 K. The surface induced reaction on quartz window was second order and the rate constant was 2.7 x 10{sup -17} mL{sup 2} molecules{sup -1} cm{sup -2} sec. Meanwhile, the 253.7 nm photon employed for mercury detection was found to accelerate the reaction. The utilization efficiency of 253.7 nm photon for Hg{sup 0} oxidation was 6.7 x 10{sup -4} molecules photon{sup -1} under the conditions employed in this study.

  8. Gas-phase thermolysis reaction of formaldehyde diperoxide. Kinetic study and theoretical mechanisms

    International Nuclear Information System (INIS)

    Jorge, Nelly Lidia; Romero, Jorge Marcelo; Grand, André; Hernández-Laguna, Alfonso

    2012-01-01

    Highlights: ► Kinetic and mechanism of the gas-phase thermolysis of tetroxane were determined. ► Gas chromatography and computational potential energy surfaces were performed. ► A mechanism in steps looked like the most probable mechanism. ► A spin–orbit coupling appeared at the singlet and triple diradical open structures. ► A non-adiabatic crossing from the singlet to the triplet state occurred. - Abstract: Gas-phase thermolysis reaction of formaldehyde diperoxide (1,2,4,5-tetroxane) was performed in an injection chamber of a gas chromatograph at a range of 463–503 K. The average Arrhenius activation energy and pre-exponential factor were 29.3 ± 0.8 kcal/mol and 5.2 × 10 13 s −1 , respectively. Critical points and reaction paths of the ground singlet and first triplet potential energy surfaces (PES) were calculated, using DFT method at BHANDHLYP/6-311+G ∗∗ level of the theory. Also, G3 calculations were performed on the reactant and products. Reaction by the ground-singlet and first-triplet states turned out to be endothermic and exothermic, respectively. The mechanism in three steps seemed to be the most probable one. An electronically non-adiabatic process appeared, in which a crossing, at an open diradical structure, from the singlet to the triplet state PES occurred, due to a spin–orbit coupling, yielding an exothermic reaction. Theoretical kinetic constant coming from the non- adiabatic transition from the singlet to the triplet state agrees with the experimental values.

  9. Gas-phase thermolysis reaction of formaldehyde diperoxide. Kinetic study and theoretical mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Jorge, Nelly Lidia [Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Av. Las Palmeras 4, 18100 Armilla, Granada (Spain); Area de Quimica Fisica Facultad de Ciencias Exactas y Naturales y Agrimensura, UNNE, Avda. Libertad 5460, 3400 Corrientes (Argentina); Romero, Jorge Marcelo [Area de Quimica Fisica Facultad de Ciencias Exactas y Naturales y Agrimensura, UNNE, Avda. Libertad 5460, 3400 Corrientes (Argentina); Grand, Andre [INAC, SCIB, Laboratoire ' Lesions des Acides Nucleiques' , UMR CEA-UJF E3, CEA-Grenoble, 17 Rue des Martyrs, 38054 Grenoble cedex 9 (France); Hernandez-Laguna, Alfonso, E-mail: ahlaguna@ugr.es [Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Av. Las Palmeras 4, 18100 Armilla, Granada (Spain)

    2012-01-17

    Highlights: Black-Right-Pointing-Pointer Kinetic and mechanism of the gas-phase thermolysis of tetroxane were determined. Black-Right-Pointing-Pointer Gas chromatography and computational potential energy surfaces were performed. Black-Right-Pointing-Pointer A mechanism in steps looked like the most probable mechanism. Black-Right-Pointing-Pointer A spin-orbit coupling appeared at the singlet and triple diradical open structures. Black-Right-Pointing-Pointer A non-adiabatic crossing from the singlet to the triplet state occurred. - Abstract: Gas-phase thermolysis reaction of formaldehyde diperoxide (1,2,4,5-tetroxane) was performed in an injection chamber of a gas chromatograph at a range of 463-503 K. The average Arrhenius activation energy and pre-exponential factor were 29.3 {+-} 0.8 kcal/mol and 5.2 Multiplication-Sign 10{sup 13} s{sup -1}, respectively. Critical points and reaction paths of the ground singlet and first triplet potential energy surfaces (PES) were calculated, using DFT method at BHANDHLYP/6-311+G{sup Asterisk-Operator Asterisk-Operator} level of the theory. Also, G3 calculations were performed on the reactant and products. Reaction by the ground-singlet and first-triplet states turned out to be endothermic and exothermic, respectively. The mechanism in three steps seemed to be the most probable one. An electronically non-adiabatic process appeared, in which a crossing, at an open diradical structure, from the singlet to the triplet state PES occurred, due to a spin-orbit coupling, yielding an exothermic reaction. Theoretical kinetic constant coming from the non- adiabatic transition from the singlet to the triplet state agrees with the experimental values.

  10. Development of a screened cathode gas flow proportional counter for in situ field determination of alpha contamination in soil

    Energy Technology Data Exchange (ETDEWEB)

    Bush, S.P.

    1997-02-01

    This study resulted in the design, construction and testing of a gas flow proportional counter for in-situ determination of soil contamination. The uniqueness of this detector is the screened material used for the cathode. A Pu-239 source of 0.006 {micro}Ci was mounted to the outside of the cathode to simulate radioactive soil. The detector probe was placed into a laboratory mock-up and tested to determine operating voltage, efficiency and energy resolution. Two gas flow proportional counters were built and tested. The detectors are cylindrical, each with a radius of 1.905 cm, having an anode wire with a radius of 0.0038 cm. The length of the smaller detector`s anode was 2.54 cm, and the length of the larger detector`s anode was 7.64 cm. Therefore, the active volumes were 28.96 cm{sup 3} and 87.10 cm{sup 3}, respectively, for the small and large detector. An operating voltage of 1,975 volts was determined to be sufficient for both detectors. The average efficiency was 2.59 {+-} 0.12% and 76.71 {+-} 10.81% for the small volume and large volume detectors, respectively. The average energy resolution for the low-energy peak of the small detector was 4.24 {+-} 1.28% and for the large-energy peak was 1.37 {+-} 0.66%. The large detectors` energy resolution was 17.75 {+-} 3.74%. The smaller detector, with better energy resolution, exhibited a bi-modal spectrum, whereas the larger detector`s spectrum centered around a single broad peak.

  11. Phase transitions and steady-state microstructures in a two-temperature lattice-gas model with mobile active impurities

    DEFF Research Database (Denmark)

    Henriksen, Jonas Rosager; Sabra, Mads Christian; Mouritsen, Ole G.

    2000-01-01

    The nonequilibrium, steady-state phase transitions and the structure of the different phases of a two-dimensional system with two thermodynamic temperatures are studied via a simple lattice-gas model with mobile active impurities ("hot/cold spots'') whose activity is controlled by an external drive....... The properties of the model are calculated by Monte Carlo computer-simulation techniques. The two temperatures and the external drive on the system lead to a rich phase diagram including regions of microstructured phases in addition to macroscopically ordered (phase-separated) and disordered phases. Depending...

  12. Gas-Phase Thermal Tautomerization of Imidazole-Acetic Acid: Theoretical and Computational Investigations

    Directory of Open Access Journals (Sweden)

    Saadullah G. Aziz

    2015-11-01

    Full Text Available The gas-phase thermal tautomerization reaction between imidazole-4-acetic (I and imidazole-5-acetic (II acids was monitored using the traditional hybrid functional (B3LYP and the long-range corrected functionals (CAM-B3LYP and ωB97XD with 6-311++G** and aug-cc-pvdz basis sets. The roles of the long-range and dispersion corrections on their geometrical parameters, thermodynamic functions, kinetics, dipole moments, Highest Occupied Molecular Orbital–Lowest Unoccupied Molecular Orbital (HOMO–LUMO energy gaps and total hyperpolarizability were investigated. All tested levels of theory predicted the preference of I over II by 0.750–0.877 kcal/mol. The origin of predilection of I is assigned to the H-bonding interaction (nN8→σ*O14–H15. This interaction stabilized I by 15.07 kcal/mol. The gas-phase interconversion between the two tautomers assumed a 1,2-proton shift mechanism, with two transition states (TS, TS1 and TS2, having energy barriers of 47.67–49.92 and 49.55–52.69 kcal/mol, respectively, and an sp3-type intermediate. A water-assisted 1,3-proton shift route brought the barrier height down to less than 20 kcal/mol in gas-phase and less than 12 kcal/mol in solution. The relatively high values of total hyperpolarizability of I compared to II were interpreted and discussed.

  13. Delivering Transmembrane Peptide Complexes to the Gas Phase Using Nanodiscs and Electrospray Ionization

    Science.gov (United States)

    Li, Jun; Richards, Michele R.; Kitova, Elena N.; Klassen, John S.

    2017-10-01

    The gas-phase conformations of dimers of the channel-forming membrane peptide gramicidin A (GA), produced from isobutanol or aqueous solutions of GA-containing nanodiscs (NDs), are investigated using electrospray ionization-ion mobility separation-mass spectrometry (ESI-IMS-MS) and molecular dynamics (MD) simulations. The IMS arrival times measured for (2GA + 2Na)2+ ions from isobutanol reveal three different conformations, with collision cross-sections (Ω) of 683 Å2 (conformation 1, C1), 708 Å2 (C2), and 737 Å2 (C3). The addition of NH4CH3CO2 produced (2GA + 2Na)2+ and (2GA + H + Na)2+ ions, with Ω similar to those of C1, C2, and C3, as well as (2GA + 2H)2+, (2GA + 2NH4)2+, and (2GA + H + NH4)2+ ions, which adopt a single conformation with a Ω similar to that of C2. These results suggest that the nature of the charging agents, imparted by the ESI process, can influence dimer conformation in the gas phase. Notably, the POPC NDs produced exclusively (2GA + 2NH4)2+ dimer ions; the DMPC NDs produced both (2GA + 2H)2+ and (2GA + 2NH4)2+ dimer ions. While the Ω of (2GA + 2H)2+ is similar to that of C2, the (2GA + 2NH4)2+ ions from NDs adopt a more compact structure, with a Ω of 656 Å2. It is proposed that this compact structure corresponds to the ion conducting single stranded head-to-head helical GA dimer. These findings highlight the potential of NDs, combined with ESI, for transferring transmembrane peptide complexes directly from lipid bilayers to the gas phase. [Figure not available: see fulltext.

  14. Evolution of Molecular and Atomic Gas Phases in the Milky Way

    Science.gov (United States)

    Koda, Jin; Scoville, Nick; Heyer, Mark

    2016-06-01

    We analyze radial and azimuthal variations of the phase balance between the molecular and atomic interstellar medium (ISM) in the Milky Way (MW) using archival CO(J = 1-0) and HI 21 cm data. In particular, the azimuthal variations—between the spiral arm and interarm regions—are analyzed without any explicit definition of the spiral arm locations. We show that the molecular gas mass fraction, I.e., {f}{{mol}}={{{Σ }}}{{{H}}2}/({{{Σ }}}{HI}+{{{Σ }}}{{{H}}2}), varies predominantly in the radial direction: starting from ˜ 100% at the center, remaining ≳ 50% to R˜ 6 {{kpc}} and decreasing to ˜10%-20% at R=8.5 {{kpc}} when averaged over the whole disk thickness (from ˜100% to ≳60%, then to ˜50% in the midplane). Azimuthal, arm-interarm variations are secondary: only ˜ 20% in the globally molecule-dominated inner MW, but becoming larger, ˜40%-50%, in the atom-dominated outskirts. This suggests that in the inner MW the gas remains highly molecular ({f}{{mol}}\\gt 50%) as it moves from an interarm region into a spiral arm and back into the next interarm region. Stellar feedback does not dissociate molecules much, and the coagulation and fragmentation of molecular clouds dominate the evolution of the ISM at these radii. The trend differs in the outskirts where the gas phase is globally atomic ({f}{{mol}}\\lt 50%). The HI and H2 phases cycle through spiral arm passage there. These different regimes of ISM evolution are also seen in external galaxies (e.g., the LMC, M33, and M51). We explain the radial gradient of {f}{{mol}} using a simple flow continuity model. The effects of spiral arms on this analysis are illustrated in the Appendix.

  15. Development of gas-phase sample-introduction techniques for analytical atomic spectrometry.

    Science.gov (United States)

    Nakahara, Taketoshi

    2005-05-01

    For the last 30 years, several types of gas-phase sample-introduction methods in analytical atomic spectrometry, i.e., atomic absorption spectrometry (AAS), atomic emission spectrometry (AES) and atomic fluorescence spectrometry (AFS), have been investigated and developed in the author's laboratory. Their fundamental results are summarized in this review article. The gas-phase sample-introduction techniques developed in the author's laboratory can be roughly divided into four groups: i) hydride generation, ii) cold-vapor generation of mercury, iii) analyte volatilization reactions and iv) miscellaneous. The analytical figures of merit of the gas-phase sample-introduction methods have been described in detail. Hydride generation has been coupled with the AAS of As, Bi, Ge, Pb, Sb, Se, Sn and Te, with the inductively coupled plasma (ICP) AES of As, Bi, Sn, Se and Sb, with the high-power nitrogen microwave-induced plasma (N2-MIP) AES of As, Bi, Pb, Sb, Se, Sn and Te by their single- and multi-element determinations, with the AFS of As, Bi, Pb, Sb, Se, Sn and Te, and with the ICP mass spectrometry (MS) of As and Se. The cold-vapor generation method for Hg has been combined with atmospheric-pressure helium microwave-induced plasma (He- or Ar-MIP)-AES and AFS. Furthermore, analyte volatilization reactions have been employed in the ICP-AES of iodine, in the He-MIP-AES of iodine bromine, chlorine, sulfur and carbon, and in the ICP-MS of sulfur. As a result, when compared with conventional solution nebulization, a great improvement in the sensitivity has been attained in each instance. In addition, the developed techniques coupled with analytical atomic spectrometry have been successfully applied to the determination of trace elements in a variety of practical samples.

  16. High performance liquid chromatographic separations of gas oil samples and their hydrotreated products using commercial normal phases.

    Science.gov (United States)

    Oro, Nicole E; Lucy, Charles A

    2011-10-28

    Three commercially available high performance liquid chromatography columns are used in normal phase or quasi-normal phase mode for the separation of gas oil samples. The columns are tested with 20 analytical standards to determine their suitability for separations of petroleum samples and their ability to separate the nitrogen group-types (pyrrole and pyridine) found in petroleum. The columns studied are polymeric hypercrosslinked polystyrene (HGN), a biphenyl phase, and a Chromegabond "DNAP" column from ES Industries. The HGN column separates gas oils based on both ring structure and heteroatom, while the biphenyl phase has low retention of most compounds studied in quasi-normal phase mode. The "DNAP" column is selective for nitrogen-containing compounds, separating them from PAHs as well as oxygen and sulphur compounds. Retention data of standards on all three columns is shown, along with chromatograms of gas oil samples on the HGN and "DNAP" columns. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Geochemical sources, forms and phases of soil contamination in an industrial city.

    Science.gov (United States)

    Harvey, P J; Rouillon, M; Dong, C; Ettler, V; Handley, H K; Taylor, M P; Tyson, E; Tennant, P; Telfer, V; Trinh, R

    2017-04-15

    This study examines current soil contamination in an Australian industrial city, Newcastle. Public (roadside verges and parks) and private (homes) surface soils (n=170) contained metal(loid)s elevated above their respective Australian Health Investigation Levels (HIL). Lead (Pb), the most common contaminant in the city, exceeds the HIL for residential soils (HIL-A, 300mg/kg) in 88% of private soils (median: 1140mg/kg). In-vitro Pb bio-accessibility analysis of selected soils (n=11) using simulated gastric fluid showed a high affinity for Pb solubilisation (maximum Pb concentration: 5190mg/kg, equating to 45% Pb bio-accessibility). Highly soluble Pb-laden Fe- and Mn-oxides likely contribute to the bio-accessibility of the Pb. Public and private space surface soils contain substantially less radiogenic Pb (range: 208 Pb/ 207 Pb: 2.345-2.411, 206 Pb/ 207 Pb: 1.068-1.312) than local background soil ( 208 Pb/ 207 Pb: 2.489, 206 Pb/ 207 Pb: 1.198), indicating anthropogenic contamination from the less radiogenic Broken Hill type Pb ores ( 208 Pb/ 207 Pb: 2.319, 206 Pb/ 207 Pb: 1.044). Source apportionment using Pb isotopic ratio quantification and soil mineralogy indicate the city's historic copper and steel industries contributed the majority of the soil contaminants through atmospheric deposition and use of slag waste as fill material. High-temperature silicates and oxides combined with rounded particles in the soil are characteristic of smelter dust emissions. Additionally, a preliminary investigation of polycyclic aromatic hydrocarbons in soils, sometimes associated with ferrous metal smelting, coal processing or burning of fossil fuels, shows that these too pose a health exposure risk (calculated in comparison to benzo(a)pyrene: n=12, max: 13.5mg/kg, HIL: 3mg/kg). Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Vapor phase elemental sulfur amendment for sequestering mercury in contaminated soil

    Science.gov (United States)

    Looney, Brian B.; Denham, Miles E.; Jackson, Dennis G.

    2014-07-08

    The process of treating elemental mercury within the soil is provided by introducing into the soil a heated vapor phase of elemental sulfur. As the vapor phase of elemental sulfur cools, sulfur is precipitated within the soil and then reacts with any elemental mercury thereby producing a reaction product that is less hazardous than elemental mercury.

  19. Gas Phase Vibrational Spectroscopy of Weakly Volatil Safe Taggants Using a Synchrotron Source

    Science.gov (United States)

    Cuisset, Arnaud; Hindle, Francis; Mouret, Gael; Gruet, Sebastien; Pirali, Olivier; Roy, Pascale

    2013-06-01

    The high performances of the AILES beamline of SOLEIL allow to study at medium resolution (0.5 cm^{-1}) the gas phase THz vibrational spectra of weakly volatil compounds. Between 2008 and 2010 we recorded and analyzed the THz/Far-IR spectra of phosphorous based nerve agents thanks to sufficient vapour pressures from liquid samples at room temperature. Recently, we extended these experiments towards the vibrational spectroscopy of vapour pressures from solid samples. This project is quite challenging since we target lower volatile compounds, and so requires very high sensitive spectrometers. Moreover a specially designed heated multipass-cell have been developped for the gas phase study of very weak vapor pressures. Thanks to skills acquired during initial studies and recent experiments performed on AILES with solid PAHs, we have recorded and assigned the gas phase vibrational fingerprints from the THz to the NIR spectral domain (10-4000 cm-1) of a set of targeted nitro-derivatives. The study was focused onto the para, ortho-mononitrotoluene (p-NT, o-NT), the 1,4 Dinitrobenzene (1,4 DNB), the 2,3-dimethyl-2,3-dinitrobutane (DMNB), and 2,4 and 2,6-dinitrotoluene (2,4-2,6 DNT), which are safe taggants widely used for the detection of commercial explosives. These taggants are usually added to plastic explosives in order to facilitate their vapour detection. Therefore, there is a continuous interest for their detection and identification in realistic conditions via optical methods. A first step consists in the recording of their gas phase vibrational spectra. These expected spectra focused onto molecules involved into defence and security domains are not yet available to date and will be very useful for the scientific community. This work is supported by the contract ANR-11-ASTR-035-01. A. Cuisset, G. Mouret, O. Pirali, P. Roy, F. Cazier, H. Nouali, J. Demaison, J. Phys. Chem. B, 2008, 112:, 12516-12525 I. Smirnova, A. Cuisset, R. Bocquet, F. Hindle, G. Mouret, O

  20. Gas-Phase Photocatalytic Oxidation of Dimethylamine: The Reaction Pathway and Kinetics

    Directory of Open Access Journals (Sweden)

    Anna Kachina

    2007-01-01

    Full Text Available Gas-phase photocatalytic oxidation (PCO and thermal catalytic oxidation (TCO of dimethylamine (DMA on titanium dioxide was studied in a continuous flow simple tubular reactor. Volatile PCO products of DMA included ammonia, formamide, carbon dioxide, and water. Ammonia was further oxidized in minor amounts to nitrous oxide and nitrogen dioxide. Effective at 573 K, TCO resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide, and water. The PCO kinetic data fit well to the monomolecular Langmuir-Hinshelwood model, whereas TCO kinetic behaviour matched the first-order process. No deactivation of the photocatalyst during the multiple long-run experiments was observed.

  1. Enantioselective supramolecular devices in the gas phase. Resorcin[4]arene as a model system

    Directory of Open Access Journals (Sweden)

    Caterina Fraschetti

    2012-04-01

    Full Text Available This review describes the state-of-art in the field of the gas-phase reactivity of diastereomeric complexes formed between a chiral artificial receptor and a biologically active molecule. The presented experimental approach is a ligand-displacement reaction carried out in a nano ESI-FT-ICR instrument, supported by a thermodynamic MS-study and molecular-mechanics and molecular-dynamics (MM/MD computational techniques. The noncovalent ion–molecule complexes are ideal for the study of chiral recognition in the absence of complicating solvent and counterion effects.

  2. Wettability in the liquid Cu-Ag alloy – fireproof material – gas phase system

    Directory of Open Access Journals (Sweden)

    G. Siwiec

    2013-07-01

    Full Text Available In the present paper, results of wettability studies on the liquid metal – fireproof material – gas phase system using copper and Cu-Ag alloys as well as typical fireproof materials, i.e. aluminium oxide, magnesium oxide and graphite, are presented. Contact angle measurements were conducted at 1 373–1 573 K by means of a high-temperature microscope coupled with a camera and a computer equipped with a program for recording and analysing images. For the measurements, the sessile drop method was used.

  3. Solvation of ions in the gas-phase: a molecular dynamics simulation

    Science.gov (United States)

    Cabarcos, Orlando M.; Lisy, James M.

    1996-07-01

    Molecular dynamics simulations have been performed on the collision between a cesium ion and a cluster of twenty methanol molecules. This process, generating a solvated ion, was studied over a range (1 to 25 eV) of eight collision energies. Preliminary analysis of this gas phase solvation has included the distribution of final ion cluster sizes, fragmentation patterns, solvation timescales and energetics. Two distinct patterns have emerged: a ballistic penetration of the neutral cluster at the higher collision energies and an evaporative evolution of the cluster ion at lower collision energies.

  4. Formation and emissions of carbonyls during and following gas-phase ozonation of indoor materials

    DEFF Research Database (Denmark)

    Poppendieck, D.G.; Hubbard, H.F.; Weschler, Charles J.

    2007-01-01

    Ozone concentrations that are several orders of magnitude greater than typical urban ambient concentrations are necessary for gas-phase ozonation of buildings, either for deodorization or for disinfection of biological agents. However, there is currently no published literature on the interaction...... relatively high BOBP releases. The greatest overall BOBP mass releases were observed for three materials that building occupants might have significant contact with: paper, office partition, and medium density fiberboard, e.g., often used in office furniture. These materials also exhibited extended BOBP...

  5. Ab initio studies of aspartic acid conformers in gas phase and in solution.

    Science.gov (United States)

    Chen, Mingliang; Lin, Zijing

    2007-10-21

    Systematic and extensive conformational searches of aspartic acid in gas phase and in solution have been performed. For the gaseous aspartic acid, a total of 1296 trial canonical structures and 216 trial zwitterionic structures were generated by allowing for all combinations of internal single-bond rotamers. All the trial structures were optimized at the B3LYP/6-311G* level and then subjected to further optimization at the B3LYP/6-311++G** level. A total of 139 canonical conformers were found, but no stable zwitterionic structure was found. The rotational constants, dipole moments, zero-point vibrational energies, harmonic frequencies, and vertical ionization energies of the canonical conformers were determined. Single-point energies were also calculated at the MP2/6-311++G** and CCSD/6-311++G** levels. The equilibrium distributions of the gaseous conformers at various temperatures were calculated. The proton affinity and gas phase basicity were calculated and the results are in excellent agreement with the experiments. The conformations in the solution were studied with different solvation models. The 216 trial zwitterionic structures were first optimized at the B3LYP/6-311G* level using the Onsager self-consistent reaction field model (SCRF) and then optimized at the B3LYP/6-311++G** level using the conductorlike polarized continuum model (CPCM) SCRF theory. A total of 22 zwitterions conformers were found. The gaseous canonical conformers were combined with the CPCM model and optimized at the B3LYP/6-311++G** level. The solvated zwitterionic and canonical structures were further examined by the discrete/SCRF model with one and two water molecules. The incremental solvation of the canonical and zwitterionic structures with up to six water molecules in gas phase was systematically examined. The studies show that combining aspartic acid with at least six water molecules in the gas phase or two water molecules and a SCRF solution model is required to provide

  6. Phase matching of high-order harmonics in a semi-infinite gas cell

    International Nuclear Information System (INIS)

    Steingrube, Daniel S.; Vockerodt, Tobias; Schulz, Emilia; Morgner, Uwe; Kovacev, Milutin

    2009-01-01

    Phase matching of high-order harmonic generation is investigated experimentally for various parameters in a semi-infinite gas-cell (SIGC) geometry. The optimized harmonic yield is identified using two different noble gases (Xe and He) and its parameter dependence is studied in a systematic way. Beside the straightforward setup of the SIGC, this geometry promises a high photon flux due to a large interaction region. Moreover, since the experimental parameters within this cell are known accurately, direct comparison to simulations is performed. Spectral splitting and blueshift of high-order harmonics are observed.

  7. Gas-Phase Anionic ?-Adduct (Trans)formations in Heteroaromatic Systems1

    OpenAIRE

    Zimnicka, Magdalena; Danikiewicz, Witold

    2015-01-01

    Anions of nitroderivatives of thiophene and furan were subjected to the reactions with selected C-H acids in the gas phase. Various structures and reaction pathways were proposed for the observed ionic products. In general, the reactions of heteroaromatic anions with C-H acids may be divided into three groups, depending on the proton affinity difference between C-H acid?s conjugate base and heteroaromatic anion (?PA). The proton transfer from C-H acid to heteroaromatic anion is a dominant pro...

  8. Predicting dermal absorption of gas-phase chemicals: transient model development, evaluation, and application

    DEFF Research Database (Denmark)

    Gong, M.; Zhang, Y.; Weschler, Charles J.

    2014-01-01

    A transient model is developed to predict dermal absorption of gas-phase chemicals via direct air-to-skin-to-blood transport under non-steady-state conditions. It differs from published models in that it considers convective mass-transfer resistance in the boundary layer of air adjacent to the skin....... Results calculated with this transient model are in good agreement with the limited experimental results that are available for comparison. The sensitivity of the modeled estimates to key parameters is examined. The model is then used to estimate air-to-skin-to-blood absorption of six phthalate esters...

  9. Gas-phase hydrosilylation of cyclohexene in an experimental radiation-chemical accelerator apparatus

    International Nuclear Information System (INIS)

    Pecherkin, A.S.; Sidorov, V.I.; Chernyshev, E.A.

    1992-01-01

    A process for the synthesis of methylcyclohexyldichlorosilane (a basic monomer for the production of organosilicon photoresists) has been investigated and perfected on an experimental apparatus with an ELV-2 electron accelerator; this synthesis involves gas-phase radiation-induced hydrosilylation of cyclohexene by methyldichlorosilane. Basic characteristics of the yield of the desired product under static conditions were determined. With the help of experiments on the synthesis of methylcyclohexyldichlorosilane in a flow- through mode, the technical features of the process of radiation-chemical hydrosilylation of cyclohexene on an accelerator apparatus were determined and studied, the optimal conditions for the synthesis were determined, and an experimental batch of the desired product was produced

  10. Atmospheric pressure plasma chemical vapor deposition reactor for 100 mm wafers, optimized for minimum contamination at low gas flow rates

    International Nuclear Information System (INIS)

    Anand, Venu; Shivashankar, S. A.; Nair, Aswathi R.; Mohan Rao, G.

    2015-01-01

    Gas discharge plasmas used for thinfilm deposition by plasma-enhanced chemical vapor deposition (PECVD) must be devoid of contaminants, like dust or active species which disturb the intended chemical reaction. In atmospheric pressure plasma systems employing an inert gas, the main source of such contamination is the residual air inside the system. To enable the construction of an atmospheric pressure plasma (APP) system with minimal contamination, we have carried out fluid dynamic simulation of the APP chamber into which an inert gas is injected at different mass flow rates. On the basis of the simulation results, we have designed and built a simple, scaled APP system, which is capable of holding a 100 mm substrate wafer, so that the presence of air (contamination) in the APP chamber is minimized with as low a flow rate of argon as possible. This is examined systematically by examining optical emission from the plasma as a function of inert gas flow rate. It is found that optical emission from the plasma shows the presence of atmospheric air, if the inlet argon flow rate is lowered below 300 sccm. That there is minimal contamination of the APP reactor built here, was verified by conducting an atmospheric pressure PECVD process under acetylene flow, combined with argon flow at 100 sccm and 500 sccm. The deposition of a polymer coating is confirmed by infrared spectroscopy. X-ray photoelectron spectroscopy shows that the polymer coating contains only 5% of oxygen, which is comparable to the oxygen content in polymer deposits obtained in low-pressure PECVD systems

  11. Gas-liquid two-phase flow behavior in terrain-inclined pipelines for gathering transport system of wet natural gas

    DEFF Research Database (Denmark)

    Yang, Yan; Li, Jingbo; Wang, Shuli

    2018-01-01

    The Volume of Fluid method and Re-Normalisation Group (RNG) k-ε turbulence model were employed to predict the gas-liquid two-phase flow in a terrain-inclined pipeline with deposited liquids. The simulation was carried out in a 22.5 m terrain-inclined pipeline with a 150 mm internal diameter...... on the liquid level under the suction force which caused by the negative pressure around the elbow, and then it touched to the top of the pipe. When the liquid blocked the pipe, the pressure drop between the upstream and downstream of the elbow increased with the increase of the gas velocity. At larger gas...

  12. Catalytic Gas-Phase Production of Lactide from Renewable Alkyl Lactates.

    Science.gov (United States)

    De Clercq, Rik; Dusselier, Michiel; Makshina, Ekaterina; Sels, Bert F

    2018-03-12

    A new route to lactide, which is a key building block of the bioplastic polylactic acid, is proposed involving a continuous catalytic gas-phase transesterification of renewable alkyl lactates in a scalable fixed-bed setup. Supported TiO 2 /SiO 2 catalysts are highly selective to lactide, with only minimal lactide racemization. The solvent-free process allows for easy product separation and recycling of unconverted alkyl lactates and recyclable lactyl intermediates. The catalytic activity of TiO 2 /SiO 2 catalysts was strongly correlated to their optical properties by DR UV/Vis spectroscopy. Catalysts with high band-gap energy of the supported TiO 2 phase, indicative of a high surface spreading of isolated Ti centers, show the highest turnover frequency per Ti site. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Formation of secondary aerosols over Europe: comparison of two gas-phase chemical mechanisms

    Science.gov (United States)

    Kim, Y.; Sartelet, K.; Seigneur, C.

    2011-01-01

    The impact of two recent gas-phase chemical kinetic mechanisms (CB05 and RACM2) on the formation of secondary inorganic and organic aerosols is compared for simulations of PM2.5 over Europe between 15 July and 15 August 2001. The host chemistry transport model is Polair3D of the Polyphemus air-quality platform. Particulate matter is modeled with a sectional aerosol model (SIREAM), which is coupled to the thermodynamic model ISORROPIA for inorganic species and to a module (MAEC) that treats both hydrophobic and hydrophilic species for secondary organic aerosol (SOA). Modifications are made to the gas-phase chemical mechanisms to handle the formation of SOA. In order to isolate the effect of the original chemical mechanisms on PM formation, the addition of reactions and chemical species needed for SOA formation was harmonized to the extent possible between the two gas-phase chemical mechanisms. Model performance is satisfactory with both mechanisms for speciated PM2.5. The monthly-mean difference of the concentration of PM2.5 is less than 1 μg m-3 (6%) over the entire domain. Secondary chemical components of PM2.5 include sulfate, nitrate, ammonium and organic aerosols, and the chemical composition of PM2.5 is not significantly different between the two mechanisms. Monthly-mean concentrations of inorganic aerosol are higher with RACM2 than with CB05 (+16% for sulfate, +11% for nitrate, and +10% for ammonium), whereas the concentrations of organic aerosols are slightly higher with CB05 than with RACM2 (+22% for anthropogenic SOA and +1% for biogenic SOA). Differences in the inorganic and organic aerosols result primarily from differences in oxidant concentrations (OH, O3 and NO3). Nitrate formation tends to be HNO3-limited over land and differences in the concentrations of nitrate are due to differences in concentration of HNO3. Differences in aerosols formed from aromatic SVOC are due to different aromatic oxidation between CB05 and RACM2. The aromatic oxidation in

  14. A local leaky-box model for the local stellar surface density-gas surface density-gas phase metallicity relation

    Science.gov (United States)

    Zhu, Guangtun Ben; Barrera-Ballesteros, Jorge K.; Heckman, Timothy M.; Zakamska, Nadia L.; Sánchez, Sebastian F.; Yan, Renbin; Brinkmann, Jonathan

    2017-07-01

    We revisit the relation between the stellar surface density, the gas surface density and the gas-phase metallicity of typical disc galaxies in the local Universe with the SDSS-IV/MaNGA survey, using the star formation rate surface density as an indicator for the gas surface density. We show that these three local parameters form a tight relationship, confirming previous works (e.g. by the PINGS and CALIFA surveys), but with a larger sample. We present a new local leaky-box model, assuming star-formation history and chemical evolution is localized except for outflowing materials. We derive closed-form solutions for the evolution of stellar surface density, gas surface density and gas-phase metallicity, and show that these parameters form a tight relation independent of initial gas density and time. We show that, with canonical values of model parameters, this predicted relation match the observed one well. In addition, we briefly describe a pathway to improving the current semi-analytic models of galaxy formation by incorporating the local leaky-box model in the cosmological context, which can potentially explain simultaneously multiple properties of Milky Way-type disc galaxies, such as the size growth and the global stellar mass-gas metallicity relation.

  15. Numerical Simulations of Liquid-Gas-Solid Three-Phase Flows in Microgravity

    Directory of Open Access Journals (Sweden)

    Xinyu Zhang

    2012-03-01

    Full Text Available Three-phase liquid-gas-solid flows under microgravity condition are studied. An Eulerian-Lagrangian computational model was developed and used in the simulations. In this approach, the liquid flow was modeled by a volume-averaged system of governing equations, whereas motions of particles and bubbles were evaluated using the Lagrangian trajectory analysis procedure. It was assumed that the bubbles remained spherical, and their shape variations were neglected. The bubble-liquid, particle-liquid and bubbl-particle two-way interactions were accounted for in the analysis. The discrete phase equations used included drag, lift, buoyancy, and virtual mass forces. Particle-particle interactions and bubble-bubble interactions were accounted for by the hard sphere model. Bubble coalescence was also included in the model. The transient flow characteristics of the three-phase flow were studied; and the effects of gravity, inlet bubble size and g-jitter acceleration on variation of flow characteristics were discussed. The low gravity simulations showed that most bubbles are aggregated in the inlet region. Also, under microgravity condition, bubble transient time is much longer than that in normal gravity. As a result, the Sauter mean bubble diameter, which is proportional to the transient time of the bubble, becomes rather large, reaching to more than 9 mm. The bubble plume in microgravity exhibits a plug type flow behavior. After the bubble plume reaches the free surface, particle volume fraction increases along the height of the column. The particles are mainly located outside the bubble plume, with very few particles being retained in the plume. In contrast to the normal gravity condition, the three phases in the column are poorly mixed under microgravity conditions. The velocities of the three phases were also found to be of the same order. Bubble size significantly affects the characteristics of the three-phase flows under microgravity conditions. For

  16. The health significance of gas- and particle-phase terpene oxidation products: a review.

    Science.gov (United States)

    Rohr, Annette C

    2013-10-01

    The reactions between terpenes and ozone (or other oxidants) produce a wide variety of both gas- and particle-phase products. Terpenes are biogenic volatile organic compounds (VOCs) that are also contained in many consumer products. Ozone is present indoors since it infiltrates into the indoor environment and is emitted by some office and consumer equipment. Some of the gaseous products formed are irritating to biological tissues, while the condensed-phase products have received attention due to their contribution to ambient fine particulate matter (PM2.5) and its respective health significance. Despite common scientific questions, the indoor and ambient air research communities have tended to operate in isolation regarding this topic. This review critically evaluates the literature related to terpene oxidation products and attempts to synthesize results of indoor and ambient air studies to better understand the health significance of these materials and identify knowledge gaps. The review documents the results of a literature search covering terpene oxidation chemistry, epidemiological, toxicological, and controlled human exposure studies, as well as health studies focused more generically on secondary organic aerosol (SOA). The literature shows a clear role for gas-phase terpene oxidation products in adverse airway effects at high concentrations; however, whether these effects occur at more environmentally relevant levels is unclear. The evidence for toxicity of particle-phase products is less conclusive. Knowledge gaps and future research needs are outlined, and include the need for more consistency in study designs, incorporation of reaction product measurements into epidemiological studies conducted in both indoor and ambient settings, and more focused research on the toxicity of SOA, especially SOA of biogenic origin. © 2013.

  17. Coherent Control of Multiphoton Transitions in the Gas and Condensed Phases with Shaped Ultrashort Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Marcos Dantus

    2008-09-23

    Controlling laser-molecule interactions has become an integral part of developing devices and applications in spectroscopy, microscopy, optical switching, micromachining and photochemistry. Coherent control of multiphoton transitions could bring a significant improvement of these methods. In microscopy, multi-photon transitions are used to activate different contrast agents and suppress background fluorescence; coherent control could generate selective probe excitation. In photochemistry, different dissociative states are accessed through two, three, or more photon transitions; coherent control could be used to select the reaction pathway and therefore the yield-specific products. For micromachining and processing a wide variety of materials, femtosecond lasers are now used routinely. Understanding the interactions between the intense femtosecond pulse and the material could lead to technologically important advances. Pulse shaping could then be used to optimize the desired outcome. The scope of our research program is to develop robust and efficient strategies to control nonlinear laser-matter interactions using ultrashort shaped pulses in gas and condensed phases. Our systematic research has led to significant developments in a number of areas relevant to the AMO Physics group at DOE, among them: generation of ultrashort phase shaped pulses, coherent control and manipulation of quantum mechanical states in gas and condensed phases, behavior of isolated molecules under intense laser fields, behavior of condensed phase matter under intense laser field and implications on micromachining with ultrashort pulses, coherent control of nanoparticles their surface plasmon waves and their nonlinear optical behavior, and observation of coherent Coulomb explosion processes at 10^16 W/cm^2. In all, the research has resulted in 36 publications (five journal covers) and nine invention disclosures, five of which have continued on to patenting

  18. Mixing in three-phase systems: Implications for enhanced oil recovery and unconventional gas extraction

    Science.gov (United States)

    Jimenez-Martinez, J.; Porter, M. L.; Hyman, J.; Carey, J. W.; Viswanathan, H. S.

    2015-12-01

    Although the mixing of fluids within a porous media is a common process in natural and industrial systems, how the degree of mixing depends on the miscibility of multiple phases is poorly characterized. Often, the direct consequence of miscible mixing is the modification of the resident fluid (brine and hydrocarbons) rheological properties. We investigate supercritical (sc)CO2 displacement and mixing processes in a three-phase system (scCO2, oil, and H2O) using a microfluidics experimental system that accommodates the high pressures and temperatures encountered in fossil fuel extraction operations. The miscibility of scCO2 with the resident fluids, low with aqueous solutions and high with hydrocarbons, impacts the mixing processes that control sweep efficiency in enhanced oil recovery (EOR) and the unlocking of the system in unconventional oil and gas extraction. Using standard volume-averaging techniques we upscale the aqueous phase saturation to the field-scale (i.e., Darcy scale) and interpret the results as a simpler two-phase system. This process allows us to perform a statistical analysis to quantify i) the degree of heterogeneity in the system resulting from the immiscible H2O and ii) how that heterogeneity impacts mixing between scCO2 and oil and their displacement. Our results show that when scCO2 is used for miscible displacement, the presence of an aqueous solution, which is common in secondary and tertiary EOR and unconventional oil and gas extraction, strongly impacts the mixing of scCO2 with the hydrocarbons due to low scCO2-H2O miscibility. H2O, which must be displaced advectively by the injected scCO2, introduces spatio-temporal variability into the system that acts as a barrier between the two miscibile fluids. This coupled with the effect of viscosity contrast, i.e., viscous fingering, has an impact on the mixing of the more miscible pair.

  19. Flow-pattern identification and nonlinear dynamics of gas-liquid two-phase flow in complex networks.

    Science.gov (United States)

    Gao, Zhongke; Jin, Ningde

    2009-06-01

    The identification of flow pattern is a basic and important issue in multiphase systems. Because of the complexity of phase interaction in gas-liquid two-phase flow, it is difficult to discern its flow pattern objectively. In this paper, we make a systematic study on the vertical upward gas-liquid two-phase flow using complex network. Three unique network construction methods are proposed to build three types of networks, i.e., flow pattern complex network (FPCN), fluid dynamic complex network (FDCN), and fluid structure complex network (FSCN). Through detecting the community structure of FPCN by the community-detection algorithm based on K -mean clustering, useful and interesting results are found which can be used for identifying five vertical upward gas-liquid two-phase flow patterns. To investigate the dynamic characteristics of gas-liquid two-phase flow, we construct 50 FDCNs under different flow conditions, and find that the power-law exponent and the network information entropy, which are sensitive to the flow pattern transition, can both characterize the nonlinear dynamics of gas-liquid two-phase flow. Furthermore, we construct FSCN and demonstrate how network statistic can be used to reveal the fluid structure of gas-liquid two-phase flow. In this paper, from a different perspective, we not only introduce complex network theory to the study of gas-liquid two-phase flow but also indicate that complex network may be a powerful tool for exploring nonlinear time series in practice.

  20. Pigging analysis for gas-liquid two phase flow in pipelines

    International Nuclear Information System (INIS)

    Kohda, K.; Suzukawa, Y.; Furukawa, H.

    1988-01-01

    A new method to analyze transient phenomena caused by pigging in gas-liquid two-phase flow is developed. During pigging, a pipeline is divided into three sections by two moving boundaries, namely the pig and the leading edge of the liquid slug in front of the pig. The basic equations are mass, momentum and energy conservation equations. The boundary conditions at the moving boundaries are determined from the mass conservation across the boundaries, etc. A finite difference method is used to solve the equations numerically. The method described above is also capable of analyzing transient two-phase flow caused by pressure and flow rate changes. Thus the over-all analysis of transient two-phase flow in pipelines becomes possible. A series of air-water two-phase flow pigging experiments was conducted using 105.3 mm diameter and 1436.5 m long test pipeline. The agreement between the measured and the calculated results is very good