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Sample records for radiatively important gases

  1. EVALUATION OF SIGNIFICANT ANTHROPOGENIC SOURCES OF RADIATIVELY IMPORTANT TRACE GASES

    EPA Science Inventory

    The report is an initial evaluation of significant anthropogenic sources of radiatively important trace gases. missions of greenhouse gases from human activities--including fossil fuel combustion, industrial/agricultural activities, and transportation--contribute to the increasin...

  2. A history of chemically and radiatively important gases in air deduced from ALE/GAGE/AGAGE

    NASA Astrophysics Data System (ADS)

    Prinn, R. G.; Weiss, R. F.; Fraser, P. J.; Simmonds, P. G.; Cunnold, D. M.; Alyea, F. N.; O'Doherty, S.; Salameh, P.; Miller, B. R.; Huang, J.; Wang, R. H. J.; Hartley, D. E.; Harth, C.; Steele, L. P.; Sturrock, G.; Midgley, P. M.; McCulloch, A.

    2000-07-01

    We describe in detail the instrumentation and calibrations used in the Atmospheric Lifetime Experiment (ALE), the Global Atmospheric Gases Experiment (GAGE), and the Advanced Global Atmospheric Gases Experiment (AGAGE) and present a history of the majority of the anthropogenic ozone-depleting and climate-forcing gases in air based on these experiments. Beginning in 1978, these three successive automated high-frequency in situ experiments have documented the long-term behavior of the measured concentrations of these gases over the past 20 years, and show both the evolution of latitudinal gradients and the high-frequency variability due to sources and circulation. We provide estimates of the long-term trends in total chlorine contained in long-lived halocarbons involved in ozone depletion. We summarize interpretations of these measurements using inverse methods to determine trace gas lifetimes and emissions. Finally, we provide a combined observational and modeled reconstruction of the evolution of chlorocarbons by latitude in the atmosphere over the past 60 years which can be used as boundary conditions for interpreting trapped air in glaciers and oceanic measurements of chlorocarbon tracers of the deep oceanic circulation. Some specific conclusions are as follows: (1) International compliance with the Montreal Protocol is so far resulting in chlorofluorocarbon and chlorocarbon mole fractions comparable to target levels; (2) mole fractions of total chlorine contained in long-lived halocarbons (CCl2F2, CCl3F, CH3CCl3, CCl4, CHClF2, CCl2FCClF2, CH3Cl, CH2Cl2, CHCl3, CCl2=CCl2) in the lower troposphere reached maximum values of about 3.6 ppb in 1993 and are beginning to slowly decrease in the global lower atmosphere; (3) the chlorofluorocarbons have atmospheric lifetimes consistent with destruction in the stratosphere being their principal removal mechanism; (4) multiannual variations in chlorofluorocarbon and chlorocarbon emissions deduced from ALE/GAGE/AGAGE data are consistent approximately with variations estimated independently from industrial production and sales data where available (CCl2F2 (CFC-12) and CCl2FCClF2 (CFC-113) show the greatest discrepancies); (5) the mole fractions of the hydrochlorofluorocarbons and hydrofluorocarbons, which are replacing the regulated halocarbons, are rising very rapidly in the atmosphere, but with the exception of the much longer manufactured CHClF2 (HCFC-22), they are not yet at levels sufficient to contribute significantly to atmospheric chlorine loading. These replacement species could in the future provide independent estimates of the global weighted-average OH concentration provided their industrial emissions are accurately documented; (6) in the future, analysis of pollution events measured using high-frequency in situ measurements of chlorofluorocarbons and their replacements may enable emission estimates at the regional level, which, together with industrial end-use data, are of sufficient accuracy to be capable of identifying regional noncompliance with the Montreal Protocol.

  3. Radiative energy transfer in molecular gases

    NASA Technical Reports Server (NTRS)

    Tiwari, Surendra N.

    1992-01-01

    Basic formulations, analyses, and numerical procedures are presented to study radiative interactions in gray as well as nongray gases under different physical and flow conditions. After preliminary fluid-dynamical considerations, essential governing equations for radiative transport are presented that are applicable under local and nonlocal thermodynamic equilibrium conditions. Auxiliary relations for relaxation times and spectral absorption models are also provided. For specific applications, several simple gaseous systems are analyzed. The first system considered consists of a gas bounded by two parallel plates having the same temperature. Within the gas there is a uniform heat source per unit volume. For this system, both vibrational nonequilibrium effects and radiation conduction interactions are studied. The second system consists of fully developed laminar flow and heat transfer in a parallel plate duct under the boundary condition of a uniform surface heat flux. For this system, effects of gray surface emittance are studied. With the single exception of a circular geometry, the third system is considered identical to the second system. Here, the influence of nongray walls is also studied.

  4. Handbook of infrared radiation from combustion gases

    NASA Technical Reports Server (NTRS)

    Ludwig, C. B.; Malkmus, W.; Reardon, J. E.; Thomson, J. A. L.; Goulard, R. (editor)

    1973-01-01

    The treatment of radiant emission and absorption by combustion gases are discussed. Typical applications include: (1) rocket combustion chambers and exhausts, (2) turbojet engines and exhausts, and (3) industrial furnaces. Some mention is made of radiant heat transfer problems in planetary atmospheres, in stellar atmospheres, and in reentry plasmas. Particular consideration is given to the temperature range from 500K to 3000K and the pressure range from 0.001 atmosphere to 30 atmospheres. Strong emphasis is given to the combustion products of hydrocarbon fuels with oxygen, specifically to carbon dioxide, water vapor, and carbon monoxide. In addition, species such as HF, HC1, CN, OH, and NO are treated.

  5. Radiation interactions in high-pressure gases

    SciTech Connect

    Christophorou, L.G. Tennessee Univ., Knoxville, TN )

    1990-01-01

    This article is on basic radiation interaction processes in dense fluids and on interphase studies aiming at the interfacing of knowledge on radiation interaction processes in the gaseous and the liquid state of matter. It is specifically focused on the effect of the density and nature of the medium on electron production in irradiated fluids and on the state, energy, transport, and attachment of slow excess electrons in dense fluids especially dielectric liquids which possess excess-electron conduction bands (V{sub 0} < 0 eV). Studies over the past two decades have shown that the interactions of low-energy electrons with molecules embedded in dense media depend not only on the molecules themselves and their internal state of excitation, but also on the electron state and energy in -- and the nature and density of -- the medium in which the interactions occur.

  6. Collisional-Radiative Kinetics in Monatomic Gases

    NASA Astrophysics Data System (ADS)

    Le, Hai; Karagozian, Ann

    2012-11-01

    A detailed model of electronic excited states is essential in capturing all the nonequilibrium processes of a partially ionized plasma by means of collisional and radiative interactions. This collisional-radiative (CR) model allows us to consider deviations from equilibrium distribution of the internal states, and is now more commonly used in the study of plasma discharges. Prior studies by Kapper and Cambier and Panesi et al. suggest that this level of detail is needed for an accurate prediction of the flow field, and it is particularly relevant to plasma-combustion interactions. The required number of excited states needed to be included in the CR model is often prohibitively large due to the nonequilibrium condition of the plasma. The consequence is a large system of ODE's which needs to be solved at each time step. A reduced mechanism for the CR model can be attained by grouping the upper states of the atomic state distribution (ASDF) into a pseudo-level in which the population is characterized either by a uniform distribution or a Boltzmann distribution. This talk presents both detailed and reduced models for an ionizing shock in Argon. Supported by the US Air Force/ERC, Inc. under subcontract RS111738.

  7. Radiative forcings for 28 potential Archean greenhouse gases

    E-print Network

    Byrne, Brendan

    2014-01-01

    Despite reduced insolation in the late Archean, evidence suggests a warm climate which was likely sustained by a stronger greenhouse effect, the so-called Faint Young Sun Problem (FYSP). CO2 and CH4 are generally thought to be the mainstays of this enhanced greenhouse, though many other gases have been proposed. We present high accuracy radiative forcings for CO2, CH4 and 26 other gases, performing the radiative transfer calculations at line-by-line resolution and using HITRAN 2012 line data for background pressures of 0.5, 1, and 2 bar of atmospheric N2. For CO2 to resolve the FYSP alone at 2.8 Gyr BP (80% of present solar luminosity), 0.32 bar is needed with 0.5 bar of atmospheric N2, 0.20 bar with 1 bar of atmospheric N2, or 0.11 bar with 2 bar of atmospheric N2. For CH4, we find that near-infrared absorption is much stronger than previously thought, arising from updates to the HITRAN database. CH4 radiative forcing peaks at 10.3, 9, or 8.3 Wm-2 for background pressures of 0.5, 1 or 2 bar, likely limiting ...

  8. A Hypothesis on Biological Protection from Space Radiation Through the Use of New Therapeutic Gases

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael P.; Ansari,Rafat R.; Nakao, Atsunori; Wink, David

    2011-01-01

    Radiation exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. The concern regarding exposure to cosmic radiation is the biological damage it induces. As damage is associated with increased oxidative stress, it is important and would be enabling to mitigate and/or prevent oxidative stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as both chemical radioprotectors for radical scavenging and biological signaling molecules for management of the body s response to exposure. From reviewing radiochemistry of water, biological effects of CO, H2, NO, and H2S gas, and mechanisms of radiation biology, it is concluded that this approach may have great therapeutic potential for radiation exposure. Furthermore, it also appears to have similar potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including, cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion injury, acute respiratory distress syndrome, parkinson s and alzheimer s disease, cataracts, and aging

  9. A Hypothesis on Biological Protection from Space Radiation Through the Use of New Therapeutic Gases

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael P.; Ansari, Rafat R.; Nakao, Atsunori; Wink, David

    2011-01-01

    Radiation exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. The concern regarding exposure to cosmic radiation is the biological damage it induces. As damage is associated with increased oxidative stress, it is important and would be enabling to mitigate and/or prevent oxidative stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as both chemical radioprotectors for radical scavenging and biological signaling molecules for management of the body s response to exposure. From reviewing radiochemistry of water, biological effects of CO, H2, NO, and H2S gas, and mechanisms of radiation biology, it is concluded that this approach may have great therapeutic potential for radiation exposure. Furthermore, it also appears to have similar potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion injury, acute respiratory distress syndrome, Parkinson s and Alzheimer s disease, cataracts, and aging.

  10. A Hypothesis on Biological Protection from Space Radiation Through the Use of Therapeutic Gases

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael

    2011-01-01

    This slide presentation proposes a hypothesis to use therapeutic gases in space to enhance the biological protection for astronauts from space radiation. The fundamental role in how radiation causes biological damage appears to be radiolysis, the dissociation of water by radiation. A chain of events appears to cause molecular and biological transformations that ultimately manifest into medical diseases. The hypothesis of this work is that applying medical gases may increase resistance to radiation, by possessing the chemical properties that effectively improve the radical scavenging and enhance bond repair and to induce biological processes which enhance and support natural resistance and repair mechanisms.

  11. Radiative Forcing by Long-Lived Greenhouse Gases: Calculations with the AER Radiative Transfer Models

    SciTech Connect

    Collins, William; Iacono, Michael J.; Delamere, Jennifer S.; Mlawer, Eli J.; Shephard, Mark W.; Clough, Shepard A.; Collins, William D.

    2008-04-01

    A primary component of the observed, recent climate change is the radiative forcing from increased concentrations of long-lived greenhouse gases (LLGHGs). Effective simulation of anthropogenic climate change by general circulation models (GCMs) is strongly dependent on the accurate representation of radiative processes associated with water vapor, ozone and LLGHGs. In the context of the increasing application of the Atmospheric and Environmental Research, Inc. (AER) radiation models within the GCM community, their capability to calculate longwave and shortwave radiative forcing for clear sky scenarios previously examined by the radiative transfer model intercomparison project (RTMIP) is presented. Forcing calculations with the AER line-by-line (LBL) models are very consistent with the RTMIP line-by-line results in the longwave and shortwave. The AER broadband models, in all but one case, calculate longwave forcings within a range of -0.20 to 0.23 W m{sup -2} of LBL calculations and shortwave forcings within a range of -0.16 to 0.38 W m{sup -2} of LBL results. These models also perform well at the surface, which RTMIP identified as a level at which GCM radiation models have particular difficulty reproducing LBL fluxes. Heating profile perturbations calculated by the broadband models generally reproduce high-resolution calculations within a few hundredths K d{sup -1} in the troposphere and within 0.15 K d{sup -1} in the peak stratospheric heating near 1 hPa. In most cases, the AER broadband models provide radiative forcing results that are in closer agreement with high 20 resolution calculations than the GCM radiation codes examined by RTMIP, which supports the application of the AER models to climate change research.

  12. Radiative interactions in molecular gases under local and nonlocal thermodynamic equilibrium conditions

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Jha, M. K.

    1993-01-01

    Basic formulations, analyses, and numerical procedures are presented to investigate radiative heat interactions in diatomic and polyatomic gases under local and nonlocal thermodynamic equilibrium conditions. Essential governing equations are presented for both gray and nongray gases. Information is provided on absorption models, relaxation times, and transfer equations. Radiative flux equations are developed which are applicable under local and nonlocal thermodynamic equilibrium conditions. The problem is solved for fully developed laminar incompressible flows between two parallel plates under the boundary condition of a uniform surface heat flux. For specific applications, three diatomic and three polyatomic gases are considered. The results are obtained numerically by employing the method of variation of parameters. The results are compared under local and nonlocal thermodynamic equilibrium conditions at different temperature and pressure conditions. Both gray and nongray studies are conducted extensively for all molecular gases considered. The particular gases selected for this investigation are CO, NO, OH, CO2, H2O, and CH4. The temperature and pressure range considered are 300-2000 K and 0.1-10 atmosphere, respectively. In general, results demonstrate that the gray gas approximation overestimates the effect of radiative interaction for all conditions. The conditions of NLTE, however, result in underestimation of radiative interactions. The method developed for this study can be extended to solve complex problems of radiative heat transfer involving nonequilibrium phenomena.

  13. A hypothesis on biological protection from space radiation through the use of new therapeutic gases as medical counter measures.

    PubMed

    Schoenfeld, Michael P; Ansari, Rafat R; Nakao, Atsunori; Wink, David

    2012-01-01

    Radiation exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. The concern regarding exposure to cosmic radiation is biological damage that is associated with increased oxidative stress. It is therefore important and would be enabling to mitigate and/or prevent oxidative stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as chemical radioprotectors for radical scavenging and as biological signaling molecules for management of the body's response to exposure. From reviewing radiochemistry of water, biological effects of CO, H2, NO, and H2S gas, and mechanisms of radiation biology, it can be concluded that this approach may have therapeutic potential for radiation exposure. Furthermore, it also appears to have similar potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion (IR) injury, acute respiratory distress syndrome, Parkinson's and Alzheimer's disease, cataracts, and aging. We envision applying these therapies through inhalation of gas mixtures or ingestion of water with dissolved gases. PMID:22475015

  14. A hypothesis on biological protection from space radiation through the use of new therapeutic gases as medical counter measures

    PubMed Central

    2012-01-01

    Radiation exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. The concern regarding exposure to cosmic radiation is biological damage that is associated with increased oxidative stress. It is therefore important and would be enabling to mitigate and/or prevent oxidative stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as chemical radioprotectors for radical scavenging and as biological signaling molecules for management of the body's response to exposure. From reviewing radiochemistry of water, biological effects of CO, H2, NO, and H2S gas, and mechanisms of radiation biology, it can be concluded that this approach may have therapeutic potential for radiation exposure. Furthermore, it also appears to have similar potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion (IR) injury, acute respiratory distress syndrome, Parkinson's and Alzheimer's disease, cataracts, and aging. We envision applying these therapies through inhalation of gas mixtures or ingestion of water with dissolved gases. PMID:22475015

  15. Principals Of Radiation Toxicology: Important Aspects.

    NASA Astrophysics Data System (ADS)

    Popov, Dmitri; Maliev, Slava; Jones, Jeffrey

    “All things are poison, and nothing is without poison; only the dose permits something not to be poisonous.” Paracelsus Key Words: Radiation Toxins (RT), Radiation Toxicants (RTc), Radiation Poisons (RP), Radiation Exposure (RE), Radiation Toxicology is the science about radiation poisons. [D.Popov et al. 2012,J.Zhou et al. 2007,] Radiation Toxins is a specific proteins with high enzymatic activity produced by living irradiated mammals. [D.Popov et al. 2012,] Radiation Toxicants is a substances that produce radiomimetics effects, adverse biological effects which specific for radiation. [D.Popov et al. 2012,] Radiation Toxic agent is specific proteins that can produce pathological biological effects specific for physical form of radiation.[D.Popov et al. 1990,2012,V. Maliev 2007] Different Toxic Substances isolated from cells or from blood or lymph circulation. [Kudriashov I. et al. 1970, D.Popov et al. 1990,2012,V. Maliev et al. 2007,] Radiation Toxins may affects many organs or specific organ, tissue, specific group of cells. [Kudriashov I. et al. 1970, D.Popov et al. 1990,2012,V. Maliev et al. 2007] For example: Radiation Toxins could induce collective toxic clinical states to include: systemic inflammatory response syndrome (SIRS),toxic multiple organ injury (TMOI), toxic multiple organ dysfunction syndromes (TMODS),and finally, toxic multiple organ failure (TMOF). [T. Azizova et al. 2005, Konchalovsky et al., 2005, D. Popov et al 2012] However, Radiation Toxins could induce specific injury of organs or tissue and induce Acute Radiation Syndromes such as Acute Radiation Cerebrovascular Syndrome, Acute Radiation Cardiovascular Syndrome, Acute Radiation Hematopoietic Syndrome, Acute Radiation GastroIntestinal Syndrome. [ D.Popov et al. 1990, 2012, V. Maliev et al. 2007] Radiation Toxins correlates with Radiation Exposure and the dose-response relationship is a fundamental and essential concept in classic Toxicology and Radiation Toxicology.[ D.Popov et al. 1990, 2012] Moderate and high doses of radiation induces necrosis of radiosensitive cells with the subsequent formation of radiation toxins and their induced acute inflammatory processes. Radiation necrosis is the most substantial and most severe form of radiation induced injury, and when widespread, has grave therapeutic implications. [D. Popov et al. 1990, 2012,Claudio A. et al. 2002, Robertson J. et al. 2002, ] Relatively small doses of Radiation Toxins induce apoptosis and high doses of Radiation Toxins induce necrosis. [Rastogi P. et al. 2009, D. Popov et al. 1990, 2012,] Threshold of Toxic Effects occurs and can be defined. [D. Popov et al. 2012, ] Radiation Toxins affects Somatic cells and Germ Cells. Radiation Toxins can induce teratogenic processes. Specific Toxicity of Radiation Toxins can affects developing fetus. Material and Methods, Results: http://www.intechopen.com/books/current-topics-in-ionizing-radiation-research/radiation-toxins-molecular-mechanisms-of-toxicity-and-radiomimetic-properties- Conclusion: Radiation is a physical agent - induce activation of some secretory proteins with high enzymatic activity. This proteins called as Radiation Toxins can produce specific for radiation biological and toxic effects after administration to radiation naive mammals. [V. Maliev et al. 2007, D. Popov et al. 1990, 2012] Radiation Toxins are teratogenic and oncogenic. Radiation Toxins effects depend on Administered Dose and Radiation effects depend on Exposure Dose and Absorbed Dose. The levels of Radiation Toxins correlates with Radiation Exposure.

  16. Comment on "Radiative forcings for 28 potential Archean greenhouse gases" by Byrne and Goldblatt (2014)

    NASA Astrophysics Data System (ADS)

    Kochanov, R. V.; Gordon, I. E.; Rothman, L. S.; Sharpe, S. W.; Johnson, T. J.; Sams, R. L.

    2015-08-01

    In the recent article by Byrne and Goldblatt, "Radiative forcing for 28 potential Archean greenhouse gases", Clim. Past. 10, 1779-1801 (2014), the authors employ the HITRAN2012 spectroscopic database to evaluate the radiative forcing of 28 Archean gases. As part of the evaluation of the status of the spectroscopy of these gases in the selected spectral region (50-1800 cm-1), the cross sections generated from the HITRAN line-by-line parameters were compared with those of the PNNL database of experimental cross sections recorded at moderate resolution. The authors claimed that for NO2, HNO3, H2CO, H2O2, HCOOH, C2H4, CH3OH and CH3Br there exist large or sometimes severe disagreements between the databases. In this work we show that for only three of these eight gases a modest discrepancy does exist between the two databases and we explain the origin of the differences. For the other five gases, the disagreements are not nearly at the scale suggested by the authors, while we explain some of the differences that do exist. In summary, the agreement between the HITRAN and PNNL databases is very good, although not perfect. Typically differences do not exceed 10 %, provided that HITRAN data exist for the bands/wavelengths of interest. It appears that a molecule-dependent combination of errors has affected the conclusions of the authors. In at least one case it appears that they did not take the correct file from PNNL (N2O4 (dimer)+ NO2 was used in place of the monomer). Finally, cross sections of HO2 from HITRAN (which do not have a PNNL counterpart) were not calculated correctly in BG, while in the case of HF misleading discussion was presented there based on the confusion by foreign or noise features in the experimental PNNL spectra.

  17. Comment on "Radiative forcings for 28 potential Archean greenhouse gases" by Byrne and Goldblatt (2014)

    DOE PAGESBeta

    Kochanov, R. V.; Gordon, I. E.; Rothman, L. S.; Sharpe, S. W.; Johnson, T. J.; Sams, R. L.

    2015-08-25

    In the recent article by Byrne and Goldblatt, "Radiative forcing for 28 potential Archean greenhouse gases", Clim. Past. 10, 1779–1801 (2014), the authors employ the HITRAN2012 spectroscopic database to evaluate the radiative forcing of 28 Archean gases. As part of the evaluation of the status of the spectroscopy of these gases in the selected spectral region (50–1800 cm-1), the cross sections generated from the HITRAN line-by-line parameters were compared with those of the PNNL database of experimental cross sections recorded at moderate resolution. The authors claimed that for NO2, HNO3, H2CO, H2O2, HCOOH, C2H4, CH3OH and CH3Br there exist largemore »or sometimes severe disagreements between the databases. In this work we show that for only three of these eight gases a modest discrepancy does exist between the two databases and we explain the origin of the differences. For the other five gases, the disagreements are not nearly at the scale suggested by the authors, while we explain some of the differences that do exist. In summary, the agreement between the HITRAN and PNNL databases is very good, although not perfect. Typically differences do not exceed 10 %, provided that HITRAN data exist for the bands/wavelengths of interest. It appears that a molecule-dependent combination of errors has affected the conclusions of the authors. In at least one case it appears that they did not take the correct file from PNNL (N2O4 (dimer)+ NO2 was used in place of the monomer). Finally, cross sections of HO2 from HITRAN (which do not have a PNNL counterpart) were not calculated correctly in BG, while in the case of HF misleading discussion was presented there based on the confusion by foreign or noise features in the experimental PNNL spectra.« less

  18. A Hypothesis on Biological Protection from Space Radiation Through the Use of New Therapeutic Gases as Medical Counter Measures

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael P.; Ansari, Rafat R.; Nakao, Atsunori; Wink, David

    2012-01-01

    Radiation exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. The concern regarding exposure to cosmic radiation is the biological damage it induces. As damage is associated with increased oxidative stress, it is important and would be enabling to mitigate and/or prevent oxidative stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as both chemical radioprotectors for radical scavenging and biological signaling molecules for management of the body s response to exposure. From reviewing radiochemistry of water, biological effects of CO, H2, NO, and H2S gas, and mechanisms of radiation biology, it is concluded that this approach may have great therapeutic potential for radiation exposure. Furthermore, it also appears to have similar potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion injury, acute respiratory distress syndrome, Parkinson s and Alzheimer s disease, cataracts, and aging.

  19. A new UK Greenhouse Gas measurement network providing ultra high-frequency measurements of key radiatively active trace gases taken from a network of tall towers

    NASA Astrophysics Data System (ADS)

    Grant, A.; O'Doherty, S.; Manning, A. J.; Simmonds, P. G.; Derwent, R. G.; Moncrieff, J. B.; Sturges, W. T.

    2012-04-01

    Monitoring of atmospheric concentrations of gases is important in assessing the impact of international policies related to the atmospheric environment. The effects of control measures on greenhouse gases introduced under the Montreal and Kyoto Protocols are now being observed. Continued monitoring is required to assess the overall success of the Protocols. For over 15 years the UK Government have funded high-frequency measurements of greenhouse gases and ozone depleting gases at Mace Head, a global background measurement station on the west coast of Ireland. These continuous, high-frequency, high-precision measurements are used to estimate regional (country-scale) emissions of greenhouse gases across the UK using an inversion methodology (NAME-Inversion) that links the Met Office atmospheric dispersion model (Numerical Atmospheric dispersion Modelling Environment - NAME) with the Mace Head observations. This unique inversion method acts to independently verify bottom up emission estimates of radiatively active and ozone-depleting trace gases. In 2011 the UK government (DECC) funded the establishment and integration of three new tall tower measurements stations in the UK, to provide enhanced resolution emission maps and decrease uncertainty of regional emission estimates produced using the NAME-Inversion. One station included in this new UK network was already established in Scotland and was used in collaboration with Edinburgh University. The two other new stations are in England and were set-up early in 2012, they contain brand new instrumentation for measurements of greenhouse gases. All three additional stations provide ultra high-frequency (1 sec) data of CO2 and CH4 using the Picarro© Cavity Ring Down Spectrometer and high frequency (20 min) measurements of N2O and SF6 from custom built sample modules with GC-ECD. We will present the new tall tower UK measurement network in detail. Using high-frequency measurements at new operational sites, including Mace Head, we will present the latest inversion results from the new network highlighting the enhanced resolution in regional emission maps for the UK. These results are presented to the UK government periodically and provide independent verification of the emission estimates of radiatively active trace gases. These results also inform policy makers on the accuracy of inventory emissions estimates of radiatively active and ozone-depleting trace gases.

  20. Comment on "Radiative forcings for 28 potential Archean greenhouse gases" by Byrne and Goldblatt (2014)

    SciTech Connect

    Kochanov, R. V.; Gordon, I. E.; Rothman, L. S.; Sharpe, S. W.; Johnson, T. J.; Sams, R. L.

    2015-08-25

    In the recent article by Byrne and Goldblatt, "Radiative forcing for 28 potential Archean greenhouse gases", Clim. Past. 10, 1779–1801 (2014), the authors employ the HITRAN2012 spectroscopic database to evaluate the radiative forcing of 28 Archean gases. As part of the evaluation of the status of the spectroscopy of these gases in the selected spectral region (50–1800 cm-1), the cross sections generated from the HITRAN line-by-line parameters were compared with those of the PNNL database of experimental cross sections recorded at moderate resolution. The authors claimed that for NO2, HNO3, H2CO, H2O2, HCOOH, C2H4, CH3OH and CH3Br there exist large or sometimes severe disagreements between the databases. In this work we show that for only three of these eight gases a modest discrepancy does exist between the two databases and we explain the origin of the differences. For the other five gases, the disagreements are not nearly at the scale suggested by the authors, while we explain some of the differences that do exist. In summary, the agreement between the HITRAN and PNNL databases is very good, although not perfect. Typically differences do not exceed 10 %, provided that HITRAN data exist for the bands/wavelengths of interest. It appears that a molecule-dependent combination of errors has affected the conclusions of the authors. In at least one case it appears that they did not take the correct file from PNNL (N2O4 (dimer)+ NO2 was used in place of the monomer). Finally, cross sections of HO2 from HITRAN (which do not have a PNNL counterpart) were not calculated correctly in BG, while in the case of HF misleading discussion was presented there based on the confusion by foreign or noise features in the experimental PNNL spectra.

  1. A comparison between weighted sum of gray gases and statistical narrow-band radiation models for combustion applications

    SciTech Connect

    Soufiani, A. . Lab. d'Energetique Moleculaire et Macroscopique); Djavdan, E. )

    1994-05-01

    The weighted sum of gray gases (WSGG) and the statistical narrow-band (SNB) models are implemented for radiative transfer calculations in realistic combustion gas mixtures and their results are compared. The WSGG model parameters are generated from SNB emissivity calculations in the [300, 2500 K] temperature range for a partial pressure ratio p[sub w]/p[sub c] = 2. In addition, the same methods are used for the resolution of the transfer equation associated with both models. Comparisons are made for the cases of planar geometry and an axisymmetrical methane--oxygen furnace. When the gas mixture is practically isothermal and surrounded by cold walls, small errors are introduced by the use of the WSGG model. On the other hand, in the case of significant temperature gradients, the inaccurate representation of gas absorptivities by the WSGG model leads to important errors.

  2. Interconversion of biologically important carboxylic acids by radiation

    NASA Technical Reports Server (NTRS)

    Negron-Mendoza, A.; Ponnamperuma, C.

    1978-01-01

    The interconversion of a group of biologically important polycarboxylic acids (acetic, fumaric, malic, malonic, succinic, citric, isocitric, tricarballylic) under gamma-ray or ultraviolet radiation was investigated. The formation of high molecular weight compounds was observed in all cases. Succinic acid was formed in almost all radiolysis experiments. Citric, malonic, and succinic acids appeared to be relatively insensitive to radiation. Interconversion of the polycarboxylic acids studied may have occurred under the effect of radiation in the prebiotic earth.

  3. Spatial variations in immediate greenhouse gases and aerosol emissions and resulting radiative forcing from wildfires in interior Alaska

    NASA Astrophysics Data System (ADS)

    Huang, Shengli; Liu, Heping; Dahal, Devendra; Jin, Suming; Li, Shuang; Liu, Shuguang

    2015-01-01

    Boreal fires can cool the climate; however, this conclusion came from individual fires and may not represent the whole story. We hypothesize that the climatic impact of boreal fires depends on local landscape heterogeneity such as burn severity, prefire vegetation type, and soil properties. To test this hypothesis, spatially explicit emission of greenhouse gases (GHGs) and aerosols and their resulting radiative forcing are required as an important and necessary component towards a full assessment. In this study, we integrated remote sensing (Landsat and MODIS) and models (carbon consumption model, emission factors model, and radiative forcing model) to calculate the carbon consumption, GHGs and aerosol emissions, and their radiative forcing of 2001-2010 fires at 30 m resolution in the Yukon River Basin of Alaska. Total carbon consumption showed significant spatial variation, with a mean of 2,615 g C m-2 and a standard deviation of 2,589 g C m-2. The carbon consumption led to different amounts of GHGs and aerosol emissions, ranging from 593.26 Tg (CO2) to 0.16 Tg (N2O). When converted to equivalent CO2 based on global warming potential metric, the maximum 20 years equivalent CO2 was black carbon (713.77 Tg), and the lowest 20 years equivalent CO2 was organic carbon (-583.13 Tg). The resulting radiative forcing also showed significant spatial variation: CO2, CH4, and N2O can cause a 20-year mean radiative forcing of 7.41 W m-2 with a standard deviation of 2.87 W m-2. This emission forcing heterogeneity indicates that different boreal fires have different climatic impacts. When considering the spatial variation of other forcings, such as surface shortwave forcing, we may conclude that some boreal fires, especially boreal deciduous fires, can warm the climate.

  4. Fast in situ gas chromatographic analysis of important atmospheric trace gases for both manned and unmanned aircraft.

    NASA Astrophysics Data System (ADS)

    Elkins, J. W.; Moore, F. L.; Hurst, D. F.; Dutton, G. S.; Nance, J. D.; Hall, B. D.

    2007-12-01

    Atmospheric trace gases play an important role in climate change, stratospheric ozone depletion, and air quality. Observations of the vertical profiles of these gases over a wide range of latitudes are extremely useful for testing climate models, estimating atmospheric lifetimes, and making estimates of emissions. Measuring the vertical and horizontal distributions from fast moving airborne platforms requires high sampling frequency. Traditional measurement technologies have included gas chromatography and mass spectroscopy. These methods can require massive size, "off the shelf" laboratory equipment along with long times (10-60 minutes) to perform the separation of gases on chromatographic adsorption columns and/or to concentrate part-per-trillion levels of these gases on adsorption traps. We have used a combination of heart-cutting chromatography, fold-back chromatography, and dual channel trapping to improve our sampling frequency. Our team also has been involved in reducing the size of the airborne instrumentation. We developed a two-channel gas chromatograph (GC) that flew during the NOAA Unmanned Aircraft Systems (UAS) Demo in 2005 and the NASA Fire Mission in 2006 on the NASA UAS Altair (General Atomics Aeronautical Systems Predator B type). It measured carbon monoxide, methane, and hydrogen on one GC channel and nitrous oxide and sulfur hexafluoride on the other channel. Customized versions of commercially available instruments for ambient temperature, relative humidity, ozone and water vapor also were incorporated into the UAS GC for the Fire mission. The ultimate goal is to further reduce the size of these instruments to suit smaller size UAS. The past successes and possibilities for the future will be addressed in this talk.

  5. Chicxulub and climate: radiative perturbations of impact-produced S-bearing gases.

    PubMed

    Pierazzo, Elisabetta; Hahmann, Andrea N; Sloan, Lisa C

    2003-01-01

    We use one-dimensional (1D) atmospheric models coupled to a sulfate aerosol model to investigate climate forcing and short-term response to stratospheric sulfate aerosols produced by the reaction of S-bearing gases and water vapor released in the Chicxulub impact event. A 1D radiation model is used to assess the climate forcing due to the impact-related loading of S-bearing gases. The model suggests that a climate forcing 100 times larger than that from the Pinatubo volcanic eruption is associated with the Chicxulub impact event for at least 2 years after the impact. In particular, we find a saturation effect in the forcing, that is, there is no significant difference in the maximum forcing between the highest (approximately 300 Gt) and lowest (approximately 30 Gt) estimated stratospheric S-loading from the Chicxulub impact. However, higher S-loads increase the overall duration of the forcing by several months. We use a single column model for a preliminary investigation of the short-term climate response to the impact-related production of sulfate aerosols (the lack of horizontal feedbacks limits the usefulness of the single column model to the first few days after the impact). Compared with the present steady-state climate, the introduction of large amounts of sulfate aerosols in the stratosphere results in a significant cooling of the Earth's surface. A long-term climate response can only be investigated with the use of a three-dimensional atmospheric model, which allows for the atmospheric circulation to adjust to the perturbation. Overall, although the climate perturbation to the forcing appears to be relatively large, the geologic record shows no sign of a significant long-term climatic shift across the K/T boundary, which is indicative of a fast post-impact climatic recovery. PMID:12804368

  6. Application of the Spectral Line-based Weighted-Sum-of-Gray-Gases model (SLWSGG) to the calculation of radiative heat transfer in steel reheating furnaces firing on low heating value gases

    NASA Astrophysics Data System (ADS)

    Nguyen, P. D.; Danda, A.; Embouazza, M.; Gazdallah, M.; Evrard, P.; Feldheim, V.

    2012-06-01

    The Spectral Line-based Weighted-Sum-of-Gray-Gases (SLWSGG) model is applied to calculate the gaseous radiative properties of the aero- or oxy-combustion products of low heating value gases issued from steel making process such as Blast Furnace Gas (BFG) as well as of high heating value gases such as Coke Oven Gas (COG) and conventional Natural Gas (NG). The comparison of total emissivities shows that the 3-gray-gases SLWSGG model is in very good agreement with the Hottel and Sarofim's database. The 3-gray-gases SLWSGG model is then integrated into AnsysFluent® Discrete Ordinates method under User Defined Function and CFD simulations are performed using these combined models. The simulations are done, with full combustion-radiation coupling, for steel reheating furnaces firing on three types of gases: BFG, COG and NG. The results are compared with the simulations realized with the 1-gray-gas WSGG model available in AnsysFluent®. The comparison shows that the 1-gray-gas WSGG model highly overestimates the steel discharging temperature as compared to the 3-gray-gases SLWSGG model. Significant temperature differences are observed between the two radiative models, i.e. 116°C, 55°C and 67°C for the BFG, COG and NG cases, respectively. It can be concluded that the 3-gray-gases SLWSGG model should be used to calculate the radiation heat transfer in large industrial furnaces with more accuracy not only for low heating value gases such as BFG but also for high heating value gases such as COG and NG.

  7. Radiative Forcing by Well-Mixed Greenhouse Gases: Estimates from Climate Models in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4)

    NASA Technical Reports Server (NTRS)

    Collins, W. D.; Ramaswamy, V.; Schwarzkopf, M. D.; Sun, Y.; Portmann, R. W.; Fu, Q.; Casanova, S. E. B.; Dufresne, J.-L.; Fillmore, D. W.; Forster, P. M. D.; Galin, V. Y.; Gohar, L. K.; Ingram, W. J.; Kratz, D. P.; Lefebvre, M.-P.; Li, J.; Marquet, P.; Oinas, V.; Tsushima, Y.; Uchiyama, T.; Zhong, W. Y.

    2006-01-01

    The radiative effects from increased concentrations of well-mixed greenhouse gases (WMGHGs) represent the most significant and best understood anthropogenic forcing of the climate system. The most comprehensive tools for simulating past and future climates influenced by WMGHGs are fully coupled atmosphere-ocean general circulation models (AOGCMs). Because of the importance of WMGHGs as forcing agents it is essential that AOGCMs compute the radiative forcing by these gases as accurately as possible. We present the results of a radiative transfer model intercomparison between the forcings computed by the radiative parameterizations of AOGCMs and by benchmark line-by-line (LBL) codes. The comparison is focused on forcing by CO2, CH4, N2O, CFC-11, CFC-12, and the increased H2O expected in warmer climates. The models included in the intercomparison include several LBL codes and most of the global models submitted to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). In general, the LBL models are in excellent agreement with each other. However, in many cases, there are substantial discrepancies among the AOGCMs and between the AOGCMs and LBL codes. In some cases this is because the AOGCMs neglect particular absorbers, in particular the near-infrared effects of CH4 and N2O, while in others it is due to the methods for modeling the radiative processes. The biases in the AOGCM forcings are generally largest at the surface level. We quantify these differences and discuss the implications for interpreting variations in forcing and response across the multimodel ensemble of AOGCM simulations assembled for the IPCC AR4.

  8. Future Climate Impacts of Direct Radiative Forcing Anthropogenic Aerosols, Tropospheric Ozone, and Long-lived Greenhouse Gases

    NASA Technical Reports Server (NTRS)

    Chen, Wei-Ting; Liao, Hong; Seinfeld, John H.

    2007-01-01

    Long-lived greenhouse gases (GHGs) are the most important driver of climate change over the next century. Aerosols and tropospheric ozone (O3) are expected to induce significant perturbations to the GHG-forced climate. To distinguish the equilibrium climate responses to changes in direct radiative forcing of anthropogenic aerosols, tropospheric ozone, and GHG between present day and year 2100, four 80-year equilibrium climates are simulated using a unified tropospheric chemistry-aerosol model within the Goddard Institute for Space Studies (GISS) general circulation model (GCM) 110. Concentrations of sulfate, nitrate, primary organic (POA) carbon, secondary organic (SOA) carbon, black carbon (BC) aerosols, and tropospheric ozone for present day and year 2100 are obtained a priori by coupled chemistry-aerosol GCM simulations, with emissions of aerosols, ozone, and precursors based on the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenario (SRES) A2. Changing anthropogenic aerosols, tropospheric ozone, and GHG from present day to year 2100 is predicted to perturb the global annual mean radiative forcing by +0.18 (considering aerosol direct effects only), +0.65, and +6.54 W m(sup -2) at the tropopause, and to induce an equilibrium global annual mean surface temperature change of +0.14, +0.32, and +5.31 K, respectively, with the largest temperature response occurring at northern high latitudes. Anthropogenic aerosols, through their direct effect, are predicted to alter the Hadley circulation owing to an increasing interhemispheric temperature gradient, leading to changes in tropical precipitation. When changes in both aerosols and tropospheric ozone are considered, the predicted patterns of change in global circulation and the hydrological cycle are similar to those induced by aerosols alone. GHG-induced climate changes, such as amplified warming over high latitudes, weakened Hadley circulation, and increasing precipitation over the Tropics and high latitudes, are consistent with predictions of a number of previous GCM studies. Finally, direct radiative forcing of anthropogenic aerosols is predicted to induce strong regional cooling over East and South Asia. Wintertime rainfall over southeastern China and the Indian subcontinent is predicted to decrease because of the increased atmospheric stability and decreased surface evaporation, while the geographic distribution of precipitation is also predicted to be altered as a result of aerosol-induced changes in wind flow.

  9. Development Of An Electronic Nose For Environmental Monitoring: Detection Of Specific Environmentally Important Gases At Their Odor Detection Threshold Concentration

    NASA Astrophysics Data System (ADS)

    Dentoni, Licinia; Capelli, Laura; Sironi, Selena; Del Rosso, Renato; Centola, Paolo; Della Torre, Matteo; Demattè, Fabrizio

    2011-09-01

    The use of a sensor array is demonstrated to be an effective approach to evaluate hazardous odor (or gas) emissions from industrial sites1. Therefore the possibility to use electronic noses for the prolonged survey of odor emissions from industrial sites is of particular interest for environmental monitoring purposes2. At the Olfactometric Laboratory of the Politecnico di Milano, in collaboration with Sacmi Group, Imola, an innovative electronic nose for the continuous monitoring of environmental odors is being developed. The aim of this work is to show the laboratory tests conducted to evaluate the capability of the electronic nose to recognize some specific environmentally important gases at their odor detection threshold concentration. The laboratory studies up to now focused on ammonia and butyric acid, those being compounds that can typically be found in the emissions from waste treatment plants, that may cause health effects when they exceed a given concentration level. The laboratory tests proved the sensors to be sensitive towards the considered compounds and the system to be capable of discriminating between odorous or non-odorous air, with a detection limit comparable with the detection limit of human nose.

  10. Second Harmonic Generation of Self-Mode-Locked ??2-Laser Radiation in GaSe and GaSeS Crystals

    NASA Astrophysics Data System (ADS)

    Genin, D. E.; Beloplotov, D. V.; Sitnikov, A. G.; Panchenko, A. N.; Sarkisov, S. Yu.; Chernyshov, A. I.

    2014-03-01

    A TEA CO2 laser generating at the wavelength ? = 10.6 ?m in the modes of free lasing and self-mode-locking was used to obtain and compare second harmonic generation (SHG) in GaSe and GaSe0.7S0.3 crystals. With the self-mode-locked laser, a 5-times higher energy efficiency of SHG was obtained. The efficiency of SHG in the GaSe0.7S0.3 crystal and its second-order nonlinear susceptibility were estimated and compared with their values for undoped GaSe.

  11. Influences of different gases on the terahertz radiation based on the application of two-color laser pulses

    NASA Astrophysics Data System (ADS)

    Moradi, S.; Ganjovi, A.; Shojaei, F.; Saeed, M.

    2015-10-01

    In this work, using a two-dimensional Particle In Cell-Monte Carlo Collision simulation method, a comparative study is performed on the influences of different types of atomic and molecular gases at various background gas pressures on the generation of broadband and intense Terahertz (THz) radiation via the application of two-color laser pulses. These two modes are focused into Argon (Ar), Xenon (Xe), Nitrogen (N2), Oxygen (O2), and air as the background gaseous media and the plasma channel is created. It is observed that the THz radiation emission dramatically changes due to the propagation effects. A wider THz pulse is emitted from the formed plasma channel at the higher gas pressures. The significant effects of the propagation features of the emitted THz pulse on its energy at the longer lengths of the plasma channel are observed.

  12. Gases of the middle atmosphere and short-term solar radiation variations

    NASA Technical Reports Server (NTRS)

    Danilin, M. YU.; Kouznetsov, G. I.

    1989-01-01

    Now there is no good agreement between theoretical and experimental data of ozone (O3) response to 27 13-day solar ultraviolet irradiance variations (SUVIV). But a few days duration SUVIV (accompanied, for example, by solar flare (SF)) has not be studied yet. The amplitudinal, diurnal, seasonal, latitudinal and phase parameters were investigated of ozone and other trace gases of atmosphere to such short term SUVIV.

  13. Coaxial radiative and convective heat transfer in gray and nongray gases

    NASA Technical Reports Server (NTRS)

    Mattick, A. T.

    1980-01-01

    Coupled radiative and convective heat transfer is investigated for an absorbing gas flowing in a finite length channel and heated by blackbody radiation directed along the flow axis. The problem is formulated in one dimension and numerical solutions are obtained for the temperature profile of the gas and for the radiation escaping the channel entrance, assuming both gray and nongray absorption spectra. Due to radiation trapping, the flowing gas is found to have substantially smaller radiation losses for a given peak gas temperature than a solid surface that is radiatively heated to this temperature. A greenhouse effect is also evident whereby radiation losses are minimized for a gas having stronger absorption at long wavelengths.

  14. Sensitivity of radiative forcing, ocean heat uptake, and climate feedback to changes in anthropogenic greenhouse gases and aerosols

    NASA Astrophysics Data System (ADS)

    Paynter, D.; Frölicher, T. L.

    2015-10-01

    We use both prescribed sea surface temperature and fully coupled versions of the Geophysical Fluid Dynamics Laboratory coupled climate model (CM3) to analyze the sensitivity of radiative forcing, ocean heat uptake, and climate feedback to changes in anthropogenic greenhouse gases and aerosols considered separately over the 1870 to 2005 period. The global anthropogenic aerosol climate feedback parameter (- ?) of -1.13 ± 0.33 Wm-2 K-1 is indistinguishable from the greenhouse gas - ? of -1.28 ± 0.23 Wm-2 K-1. However, this greenhouse gas climate feedback parameter is about 50% larger than that obtained for CM3 from a widely used linear extrapolation method of regressing Earth's top of atmosphere imbalance against surface air temperature change in idealized CO2 radiative forcing experiments. This implies that the global mean surface temperature change due to forcing over the 1870-2005 period is 50% smaller than that predicted using the climate feedback parameter obtained from idealized experiments. This difference results from time dependence in ?, which makes the radiative forcing obtained by the fixed sea surface temperature method incompatible with that obtained by the linear extrapolation method fitted over the first 150 years after CO2 is quadrupled. On a regional scale, ? varies greatly between the greenhouse gas and aerosol case. This suggests that the relationship between transient and equilibrium climate sensitivities obtained from idealized CO2 simulations, using techniques such as regional feedback analysis and heat uptake efficacy, may not hold for other forcing scenarios.

  15. Shifting of infrared radiation using rotational raman resonances in diatomic molecular gases

    DOEpatents

    Kurnit, Norman A. (Santa Fe, NM)

    1980-01-01

    A device for shifting the frequency of infrared radiation from a CO.sub.2 laser by stimulated Raman scattering in either H.sub.2 or D.sub.2. The device of the preferred embodiment comprises an H.sub.2 Raman laser having dichroic mirrors which are reflective for 16 .mu.m radiation and transmittive for 10 .mu.m, disposed at opposite ends of an interaction cell. The interaction cell contains a diatomic molecular gas, e.g., H.sub.2, D.sub.2, T.sub.2, HD, HT, DT and a capillary waveguide disposed within the cell. A liquid nitrogen jacket is provided around the capillary waveguide for the purpose of cooling. In another embodiment the input CO.sub.2 radiation is circularly polarized using a Fresnel rhomb .lambda./4 plate and applied to an interaction cell of much longer length for single pass operation.

  16. Search for Positronium Lyman ?-Radiation from Positrons Stopped in Inert Gases*

    PubMed Central

    Leventhal, Marvin

    1970-01-01

    An attempt to detect the positronium Lyman ?-radiation at 2430 Å is reported. Positrons from an intense 64Cu source (20 Ci) were stopped in high purity A, Ne, and He at pressures ranging from 0.01 to 3.0 atm. Light from the stopping region was collected by a large solid-angle light pipe and directed to a photomultiplier. Spectra were obtained by inserting a series of optical interference filters in front of the photomultiplier. Identical spectra were obtained with an intense electron emitter replacing the 64Cu source. These results indicate that any Lyman ?-radiation present at the photomultiplier is masked by a large background continuum associated with gas excitation processes. The data were employed to set an upper limit of 1 in 2000 on those positrons stopping in the gas which result in Lyman ?-radiation. PMID:16591834

  17. Atmospheric radiation

    SciTech Connect

    Harshvardhan, M.R. )

    1991-01-01

    Studies of atmospheric radiative processes are summarized for the period 1987-1990. Topics discussed include radiation modeling; clouds and radiation; radiative effects in dynamics and climate; radiation budget and aerosol effects; and gaseous absorption, particulate scattering and surface reflection. It is concluded that the key developments of the period are a defining of the radiative forcing to the climate system by trace gases and clouds, the recognition that cloud microphysics and morphology need to be incorporated not only into radiation models but also climate models, and the isolation of a few important unsolved theoretical problems in atmospheric radiation.

  18. Effect of pollutant gases on ozone production by simulated solar radiation

    NASA Technical Reports Server (NTRS)

    Wong, E. L.; Bittker, D. A.

    1974-01-01

    Experiments using simulated solar radiation in a chamber, with a controlled atmospheric pressure near 1 atmosphere, were conducted to evaluate O3 production. The effects of CO and H2O were analyzed to determine if the CO and H2O addition could reduce NO destruction of O3. The results show that NO is destroyed while destroying O3.

  19. Intracavity absorption of CO 2 laser radiation by chlorofluorocarbon (CFC) gases

    NASA Astrophysics Data System (ADS)

    Al-Hawat, Sh.

    2008-05-01

    Intracavity absorption method was applied to determine the absorption coefficients of trichlorofluorocarbon CCl 3F (CFC-11), dichlorodifluorocarbon CF 2Cl 2 (CFC-12) and chlorodifluorocarbon CHClF 2 (CFC-22) vs. the pressure in the cell inside the cavity of a tunable CO 2 laser at different spectral lines on branches 9R and 10P. The laser output power was measured vs. the gas pressure at different spectral lines on branches 9R, 9P, 10R and 10P of CO 2 molecule transitions. A strong absorption was observed for lines of 9R and 10P branches, whereas a weak absorption was noticed for lines of 9P and 10R branches. The calculation of absorption coefficients was restricted for 9R and 10P due to the oscillating variation of the output power of CO 2 laser vs. the CFC pressure, which was occurred for the lines of 9P and 10R. On the basis of absorption coefficients, the absorption cross-sections for CFC-12 were calculated and compared with the absorption cross-sections found from the previous experiment (where the cell was located outside the cavity), NIST and HITRAN databases, respectively. The obtained data could be useful for CFC gases detection as pollutants in the atmosphere.

  20. Implantation of high concentration noble gases in cubic zirconia and silicon carbide: A contrasted radiation tolerance

    NASA Astrophysics Data System (ADS)

    Veli?a, Gihan; Debelle, Aurélien; Thomé, Lionel; Mylonas, Stamatis; Vincent, Laetitia; Boulle, Alexandre; Jagielski, Jacek; Pantelica, Dan

    2014-08-01

    The modifications of the microstructure of yttria-stabilized cubic zirconia and silicon carbide single crystals implanted with high concentrations of noble gas ions and subsequently annealed at high temperature were characterized using RBS/C, XRD and TEM. It is found that the annealing behavior is strongly dependent on both the material and the implanted noble gases. Ar-implanted yttria-stabilized zirconia shows no significant microstructural modification upon annealing at 800 °C, e.g. dislocations are still present and the size of the Ar bubbles does not evolve. This is in strong contrast with previous observations on helium-implanted zirconia, where the formation of bubbles and elongated fractures were observed. In the case of SiC, thermal annealing at 1000 °C shows an enhanced damage recovery when He is implanted as compared to Ar implantation and the recrystallization of the matrix is accompanied with the release of noble gas atoms. This difference can be ascribed to different atomic radii, and thus mobility of implanted species.

  1. A Hypothesis on Biological Protection from Space Radiation Through the Use of New Therapeutic Gases as Medical Counter Measures

    NASA Technical Reports Server (NTRS)

    Schoenfeld, Michael P.; Ansari, Rafat R.; Nakao, Atsunori; Wink, David

    2011-01-01

    Exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. As biological damage from exposure is associated with increased oxidative stress, it would be enabling to mitigate and/or prevent stress prior to the development of clinical symptoms and disease. This paper hypothesizes a "systems biology" approach in which a combination of chemical and biological mitigation techniques are used conjunctively. It proposes using new, therapeutic, medical gases as both chemical radioprotectors for radical scavenging and biological promoters for management of the body s response to exposure. From reviewing radiochemistry of water, biological effects of CO, H2, NO, and H2S gas, and mechanisms of radiation biology, it is concluded that this approach may have great therapeutic potential for exposure. Furthermore, it also appears to have potential for curtailing the pathogenesis of other diseases in which oxidative stress has been implicated including cardiovascular disease, cancer, chronic inflammatory disease, hypertension, ischemia/reperfusion injury, acute respiratory distress syndrome, Parkinson s and Alzheimer s disease, cataracts, and aging.

  2. Radiative Interaction Between Driver and Driven Gases in an Arc-Driven Shock Tube

    NASA Technical Reports Server (NTRS)

    Bogdanoff, David W.; Park, Chul

    2001-01-01

    An electric-arc driven shock tube was operated with hydrogen as the driven gas and either hydrogen or helium as the driver gas. Electron density was measured behind the primary shock wave spectroscopically from the width of the Beta line of hydrogen. The measured electron density values were many times greater than the values calculated by the Rankine - Hugoniot relations. By accounting for the radiative transfer from the driver gas to the driven gas, the measured electron density values were numerically recreated.

  3. Greenhouse Gases

    MedlinePLUS

    ... effects. More about how greenhouse gases affect the climate » Also on Energy Explained Energy and the Environment Where Greenhouse Gases ... 44&aid=8 Last reviewed: September 25, 2015 « Energy and the Environment Greenhouse Gases’ Effect on the Climate »

  4. Changes in partial pressures of respiratory gases during submerged voluntary breath hold across odontocetes: is body mass important?

    PubMed

    Noren, S R; Williams, T M; Ramirez, K; Boehm, J; Glenn, M; Cornell, L

    2012-02-01

    Odontocetes have an exceptional range in body mass spanning 10(3) kg across species. Because, size influences oxygen utilization and carbon dioxide production rates in mammals, this lineage likely displays an extraordinary variation in oxygen store management compared to other marine mammal groups. To examine this, we measured changes in the partial pressures of respiratory gases ([Formula: see text], [Formula: see text]), pH, and lactate in the blood during voluntary, quiescent, submerged breath holds in Pacific white-sided dolphins (Lagenorhynchus obliquidens), bottlenose dolphins (Tursiops truncatus), and a killer whale (Orcinus orca) representing a mass range of 96-3,850 kg. These measurements provided an empirical determination of the effect of body size on the variability in blood biochemistry during breath hold and experimentally determined aerobic dive limits (ADL) within one taxonomic group (odontocetes). For the species in this study, maximum voluntary breath-hold duration was positively correlated with body mass, ranging from 3.5 min in white-sided dolphins to 13.3 min for the killer whale. Variation in breath-hold duration was associated with differences in the rate of change for [Formula: see text] throughout breath hold; [Formula: see text] decreased twice as fast for the two smaller species (-0.6 mmHg O(2) min(-1)) compared to the largest species (-0.3 mmHg O(2) min(-1)). In contrast, the rate of increase in [Formula: see text] during breath hold was similar across species. These results demonstrate that large body size in odontocetes facilitates increased aerobic breath-hold capacity as mediated by decreased mass-specific metabolic rates (rates of change in [Formula: see text] served as a proxy for oxygen utilization). Indeed the experimentally determined 5 min ADL for bottlenose dolphins was surpassed by the 13.3 min maximum breath hold of the killer whale, which did not end in a rise in lactate. Rather, breath hold ended voluntarily as respiratory gases and pH fell within a narrow range for both large and small species, likely providing cues for ventilation. PMID:21935721

  5. Noble Gases

    NASA Astrophysics Data System (ADS)

    Podosek, F. A.

    2003-12-01

    The noble gases are the group of elements - helium, neon, argon, krypton, xenon - in the rightmost column of the periodic table of the elements, those which have "filled" outermost shells of electrons (two for helium, eight for the others). This configuration of electrons results in a neutral atom that has relatively low electron affinity and relatively high ionization energy. In consequence, in most natural circumstances these elements do not form chemical compounds, whence they are called "noble." Similarly, much more so than other elements in most circumstances, they partition strongly into a gas phase (as monatomic gas), so that they are called the "noble gases" (also, "inert gases"). (It should be noted, of course, that there is a sixth noble gas, radon, but all isotopes of radon are radioactive, with maximum half-life a few days, so that radon occurs in nature only because of recent production in the U-Th decay chains. The factors that govern the distribution of radon isotopes are thus quite different from those for the five gases cited. There are interesting stories about radon, but they are very different from those about the first five noble gases, and are thus outside the scope of this chapter.)In the nuclear fires in which the elements are forged, the creation and destruction of a given nuclear species depends on its nuclear properties, not on whether it will have a filled outermost shell when things cool off and nuclei begin to gather electrons. The numerology of nuclear physics is different from that of chemistry, so that in the cosmos at large there is nothing systematically special about the abundances of the noble gases as compared to other elements. We live in a very nonrepresentative part of the cosmos, however. As is discussed elsewhere in this volume, the outstanding generalization about the geo-/cosmochemistry of the terrestrial planets is that at some point thermodynamic conditions dictated phase separation of solids from gases, and that the Earth and the rest of the inner solar were made by collecting the solids, to the rather efficient exclusion of the gases. In this grand separation the noble gases, because they are noble, were partitioned strongly into the gas phase. The resultant generalization is that the noble gases are very scarce in the materials of the inner solar system, whence their common synonym "rare gases."This scarcity is probably the most important single feature to remember about noble-gas cosmochemistry. As illustration of the absolute quantities, for example, a meteorite that contains xenon at a concentration of order 10 -10 cm3STP g -1 (4×10-15 mol g-1) would be considered relatively rich in xenon. Yet this is only 0.6 ppt (part per trillion, fractional abundance 10-12) by mass. In most circumstances, an element would be considered efficiently excluded from some sample if its abundance, relative to cosmic proportions to some convenient reference element, were depleted by "several" orders of magnitude. But a noble gas would be considered to be present in quite high concentration if it were depleted by only four or five orders of magnitude (in the example above, 10-10 cm3STP g-1 of xenon corresponds to depletion by seven orders of magnitude), and one not uncommonly encounters noble-gas depletion of more than 10 orders of magnitude.The second most important feature to note about noble-gas cosmochemistry is that while a good deal of the attention given to noble gases really is about chemistry, traditionally a good deal of attention is also devoted to nuclear phenomena, much more so than for most other elements. This feature is a corollary of the first feature noted above, namely scarcity. A variety of nuclear transmutation processes - decay of natural radionuclides and energetic particle reactions - lead to the production of new nuclei that are often new elements. Most commonly, the quantity of new nuclei originating in nuclear transmutation is very small compared to the quantity already present in the sample in question,

  6. Trends in source gases

    NASA Technical Reports Server (NTRS)

    Ehhalt, D. H.; Fraser, P. J.; Albritton, D.; Cicerone, R. J.; Khalil, M. A. K.; Legrand, M.; Makide, Y.; Rowland, F. S.; Steele, L. P.; Zander, R.

    1989-01-01

    Source gases are defined as those gases that, by their breakdown, introduce into the stratosphere halogen, hydrogen, and nitrogen compounds that are important in stratospheric ozone destruction. Given here is an update of the existing concentration time series for chlorocarbons, nitrous oxide, and methane. Also reviewed is information on halogen containing species and the use of these data for establishing trends. Also reviewed is evidence on trends in trace gases that influence tropospheric chemistry and thus the tropospheric lifetimes of source gases, such as carbon dioxide, carbon monoxide, or nitrogen oxides. Much of the information is given in tabular form.

  7. NOBLE GASES

    EPA Science Inventory

    The Noble Gases symposium, on which this report is based, provided comprehensive coverage of the noble gases. The coverage included, but was not limited to, the properties, biokinetics, bioeffects, production and release to the environment, detection techniques, standards, and ap...

  8. Momentum transfer by an internal source of ionizing radiation - an important feedback process during galaxy formation ?!

    E-print Network

    Martin G. Haehnelt

    1994-10-25

    The role of momentum transfer (``radiation pressure'') due to an internal source of ionizing radiation for the formation of baryonic structures is investigated. Fully-ionized self-gravitating gaseous objects can be radiation-pressure supported on a characteristic length scale $D_{\\rm rp} \\sim 100 \\pc - 3 \\kpc$. On smaller scales momentum transfer due to ionizing radiation will be the dominant force and for spherical collapsing objects of mass $\\la 10^{10}\\Msol$ a complete bounce is possible. A population of massive stars and/or accretion onto a central compact object are natural sources of ionizing radiation in newly-forming baryonic structures. Radiation pressure is therefore likely to play an important role for the dynamical and thermal evolution of the intergalactic medium and the mass-to-light ratio of small galaxies. The effect will be especially important for hierarchical cosmogonies where galactic structures build up by merging of smaller objects. Radiation pressure due to ionizing radiation might furthermore be responsible for substructures of size $D_{\\rm rp}$ in the stellar component of large galaxies.

  9. Sources of black carbon aerosols in South Asia and surrounding regions during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)

    NASA Astrophysics Data System (ADS)

    Kumar, R.; Barth, M. C.; Nair, V. S.; Pfister, G. G.; Babu, S. S.; Satheesh, S. K.; Moorthy, K. K.; Carmichael, G. R.

    2014-12-01

    The dominant sources of black carbon (BC) in South Asia and surrounding regions are inferred during March-May 2006 (Integrated Campaign for Aerosols, Gases and Radiation Budget, ICARB) period by introducing BC tracers in the Weather Research and Forecasting Model coupled with Chemistry. The model reproduced the magnitude, temporal and spatial variability of BC distribution observed during the ICARB ship-cruise. Average and SD (representing the spatial and temporal variability) in observed and modeled BC mass concentrations along the ship-track are estimated as 755 ± 734 and 732 ± 913 ng m-3 respectively. Average modeled values at most of the inland stations were also found to fall within the range of observed values. Model results show that ICARB measurements were fairly well representative of the Arabian Sea and the Bay of Bengal during the pre-monsoon season. Results show that anthropogenic and biomass burning emissions, respectively, accounted for 70 and 28 % of the average ± SD BC mass concentration (1480 ± 5920 ng m-3) in South Asia. BC emissions from residential (49 %) and industrial (37 %) sectors appear to be the major anthropogenic sources, except in the Himalayas where vehicular emissions dominated. We find that, while all parts of continental India contributed to anthropogenic BC over the Bay of Bengal, contribution over the Arabian Sea came mostly from southern Peninsula. We also show that regional-scale transport of anthropogenic emissions contribute up to 30 % of BC mass concentrations in western and eastern India, suggesting that it is important to consider non-local sources along with the local emissions while designing strategies for mitigating BC emissions.

  10. Sources of Black Carbon Aerosols in South Asia and Surrounding Regions During the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)

    NASA Astrophysics Data System (ADS)

    Kumar, R.; Barth, M. C.; Nair, V. S.; Pfister, G.; Babu, S. S.; Satheesh, S. K.; Krishnamoorthy, K.; Carmichael, G. R.

    2014-12-01

    The dominant sources of black carbon (BC) in South Asia and surrounding regions are inferred during March-May 2006 (Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)) by introducing BC tracers in the Weather Research and Forecasting Model coupled with Chemistry. Model results show that ICARB measurements were fairly well representative of the Arabian Sea and the Bay of Bengal during the pre-monsoon season. The model reproduced well the magnitude, temporal and spatial variability of BC concentrations observed during the ICARB ship-cruise. Average and standard deviation (representing the spatial and temporal variability) in observed and modeled BC mass concentrations along the ship-track are estimated as 755±734 ng m-3 and 732±913 ng m-3 respectively, where the standard deviation represents the spatial and temporal variability in the region. Average modeled values at most of the inland stations were also found to fall within the range of observed values. Results show that anthropogenic and biomass burning emissions, respectively, accounted for 70% and 28% of the BC mass concentration in South Asia. BC emissions from residential (49%) and industrial (37%) sectors appear to be the major anthropogenic sources, except in the Himalayas where vehicular emissions dominate. We find that, while all parts of continental India contributed to anthropogenic BC over Bay of Bengal, contribution over the Arabian Sea came mostly from southern Peninsula. We also show that long-range transport of anthropogenic emissions contribute up to 30% of BC concentrations in western and eastern India, suggesting that it is important to consider non-local sources along with the local emissions while designing strategies for mitigating BC emissions.

  11. Radiatively important parameters best estimate (RIPBE) value-added product (VAP)

    SciTech Connect

    Shippert,T.; Jensen,M.; McFarlane, S.; Mather, J.; Flynn, C.; Mlawer, E.; Delamere, J.; Oreopoulos, L.; Turner, D.; Xie, S.

    2010-03-15

    Currently, to calculate radiative heating rate profiles for the Broadband Heating Rate Profile (BBHRP) product, radiatively important parameters (water vapor, ozone, surface albedo, aerosol properties, and cloud properties) from multiple VAPs and datastreams are combined into input text files that are then used to run the RRTM radiative transfer codes. These input parameters have different temporal and spatial scales and are difficult to extract from the text files to be used for other purposes such as running other radiative transfer codes, analyzing results, or error tracking. The purpose of the Radiatively Important Parameters Best Estimate (RIPBE) VAP is to improve this process by creating a clearly identified set of inputs for BBHRP (and other radiation codes) on a uniform vertical and temporal grid. This process will decouple the input/output portion of the BBHRP from the core physics (the RRTM radiative transfer model) and will add error tracking and version information to the input data set. Critical parameters (which must exist for the radiation code to be run) will be designated; for other parameters, climatological or fixed values will be used when the preferred values are missing. This should increase the number of cases for which radiative transfer calculations can be run. In all cases, flags will clearly identify the source for each parameter. RIPBE will serve multiple functions: (1) it will provide a clearly identifiable set of inputs for BBHRP, (2) it will facilitate the use of BBHRP as a retrieval and radiation code development testbed by providing a vehicle for easily extracting and swapping input parameters needed to conduct radiative transfer calculations, and (3) it will be a complement to the Climate Modeling Best Estimate (CMBE) VAP and will provide a significantly expanded set of parameters for model evaluation in a showcase data set form. At the ASR meeting, we will present examples and evaluation of the initial RIPBE dataset at SGP.

  12. Radiatively Important Parameters Best Estimate (RIPBE): An ARM Value-Added Product

    SciTech Connect

    McFarlane, S; Shippert, T; Mather, J

    2011-06-30

    The Radiatively Important Parameters Best Estimate (RIPBE) VAP was developed to create a complete set of clearly identified set of parameters on a uniform vertical and temporal grid to use as input to a radiative transfer model. One of the main drivers for RIPBE was as input to the Broadband Heating Rate Profile (BBHRP) VAP, but we also envision using RIPBE files for user-run radiative transfer codes, as part of cloud/aerosol retrieval testbeds, and as input to averaged datastreams for model evaluation.

  13. Greenhouse Gases CHAPTER 4 Why some gases are greenhouse gases, but

    E-print Network

    . It has the essential ingre- dient of the greenhouse effect, but it is missing numerous thingsGreenhouse Gases CHAPTER 4 Why some gases are greenhouse gases, but most aren't, and some that are important in the real atmosphere. Starting from the Layer Model, the next few chapters add things one

  14. MODELLING OF EXPLOSIVE EVENTS IN THE SOLAR TRANSITION REGION: IMPORTANCE OF RADIATIVE LOSSES AND THERMAL CONDUCTION

    E-print Network

    1 MODELLING OF EXPLOSIVE EVENTS IN THE SOLAR TRANSITION REGION: IMPORTANCE OF RADIATIVE LOSSES and the pre­existing network field, which is widely believed to cause explosive events observed in the solar region; explosive events; numerical simulations 1. INTRODUCTION High resolution ultra­violet (UV) spectra

  15. The Bakerian Lecture: On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connexion of Radiation, Absorption, and Conduction

    E-print Network

    Noone, David

    , and on the Physical Connexion of Radiation, Absorption, and Conduction Author(s): John Tyndall Source: Philosophical Radiation,Absorption,and Conduction. By JOIIN TYNDALL, JEsq.,F.R.S., MIemberof the AcadeLmiesand Societiesof

  16. Measurements of Ice Particles in Tropical Cirrus Anvils: Importance in Radiation Balance

    NASA Technical Reports Server (NTRS)

    Foster, Theodore; Arnott, William P.; Hallett, John; Pueschel, Rudi; Strawn, Anthony W. (Technical Monitor)

    1994-01-01

    Cirrus is important in the radiation balance of the global atmosphere, both at solar and thermal infrared (IR) wavelengths. In particular cirrus produced by deep convection over the oceans in the tropics may be critical in controlling processes whereby energy from warm tropical oceans is injected to different levels in the tropical atmosphere to subsequently influence not only tropical but mid latitude climate. Details of the cloud composition may differentiate between a net cooling or warming at these levels. The cloud composition may change depending on the input of nuclei from volcanic or other sources. Observations of cirrus during the FIRE-2 Project over Coffeyville, Kansas and by satellite demonstrate that cirrus, on occasion, is composed not only of larger particles with significant fall velocity (few hundred micrometers, 0.5 m/s) but much more numerous small particles, size 10-20 micrometers, with small fall velocity (cm/s), which may sometimes dominate the radiation field. This is consistent with emissivity measurements. In the thermal IR, ice absorption is strong, so that ice particles only 10 micrometers thick are opaque, at some wavelengths; on the other hand at other wavelengths and in the visible, ice is only moderately to weakly absorbing. It follows that for strongly absorbing wavelengths the average projected area of the ice particles is the important parameter, in weakly absorbing regions it is the volume (mass) of ice which is important. The shape of particles and also their internal structure may also have significant effect on their radiative properties. In order to access the role of cirrus in the radiation budget it is necessary to measure the distribution of ice particles sizes, shapes and concentrations in the regions of interest. A casual observation of any cirrus cloud shows that there is variability down to a scale of at least a few 100 m; this is confirmed by radar and lidar remote sensing. Thus aircraft measurements designed to give insight into the spatial distribution of radiation properties of ice crystals must be capable of examination of concentration, size and shape over a distance ideally of 100 m or less and to detect particles down to a size below which radiative effects are no longer significant.

  17. Dependence of the absorption of pulsed CO{sub 2}-laser radiation by silane on wavenumber, fluence, pulse duration, temperature, optical path length, and pressure of absorbing and nonabsorbing gases

    SciTech Connect

    Blazejowski, J.; Gruzdiewa, L.; Rulewski, J.; Lampe, F.W.

    1995-05-15

    The absorption of three lines [{ital P}(20), 944.2 cm{sup {minus}1}; {ital P}(14), 949.2 cm{sup {minus}1}; and {ital R}(24), 978.5 cm{sup {minus}1}] of the pulsed CO{sub 2} laser (00{sup 0}1--10{sup 0}0 transition) by SiH{sub 4} was measured at various pulse energy, pulse duration, temperature, optical path length, and pressure of the compound and nonabsorbing foreign gases. In addition, low intensity infrared absorption spectrum of silane was compared with high intensity absorption characteristics for all lines of the pulsed CO{sub 2} laser. The experimental dependencies show deviations from the phenomenological Beer--Lambert law which can be considered as arising from the high intensity of an incident radiation and collisions of absorbing molecules with surroundings. These effects were included into the expression, being an extended form of the Beer--Lambert law, which reasonably approximates all experimental data. The results, except for extending knowledge on the interaction of a high power laser radiation with matter, can help understanding and planning processes leading to preparation of silicon-containing technologically important materials.

  18. Superradiance in ultracold Rydberg gases

    NASA Astrophysics Data System (ADS)

    Wang, T.; Yelin, S. F.; Côté, R.; Eyler, E. E.; Farooqi, S. M.; Gould, P. L.; Koštrun, M.; Tong, D.; Vrinceanu, D.

    2007-03-01

    Experiments in dense, ultracold gases of rubidium Rydberg atoms show a considerable decrease of the radiative excited state lifetimes compared to dilute gases. This accelerated decay is explained by collective and cooperative effects, leading to superradiance. A formalism to calculate effective decay times in a dense Rydberg gas shows that for these atoms the decay into nearby levels increases by up to three orders of magnitude. Excellent agreement between theory and experiment follows from this treatment of Rydberg decay behavior.

  19. Perceived Incidence and Importance of Lay-Ideas on Ionizing Radiation: Results of a Delphi-Study among Radiation-Experts.

    ERIC Educational Resources Information Center

    Eijkelhof, H. M. C.; And Others

    1990-01-01

    Described are lay-ideas which may exist about ionizing radiation, the importance of these ideas for risk management, and the relationships between various lay-ideas. Lay-ideas were used to gain a better insight into the problems of learning about ionizing radiation and to construct appropriate teaching materials and strategies. (KR)

  20. Impact of Desert Dust Radiative Forcing on Sahel Precipitation: Relative importance of dust compared to sea surface temperature variations, vegetation

    E-print Network

    Mahowald, Natalie

    1 Impact of Desert Dust Radiative Forcing on Sahel Precipitation: Relative importance of dust of Climate #12;2 Abstract The role of direct radiative forcing of desert dust aerosol in the change from wet the observed change in desert dust when allowing dust to respond to changes in simulated climate, even

  1. Importance of maintenance therapy in C225-induced enhancement of tumor control by fractionated radiation

    SciTech Connect

    Milas, Luka . E-mail: lmilas@mdanderson.org; Fang, F.-M.; Mason, Kathy A.; Valdecanas, David B.S.; Hunter, Nancy; Koto, Masashi; Ang, K. Kian

    2007-02-01

    Purpose: C225 strongly enhances tumor radioresponse when given concurrently with radiotherapy. We investigated whether additional therapeutic benefit could be achieved by continuing maintenance treatment with C225 after the completion of fractionated radiotherapy. Methods and Materials: A431 xenografts were treated with local irradiation or combined with C225 by two different schedules: (1) 6 h before the first dose of irradiation and at 3-day intervals for a total of 3 doses during the 7-day fractionated radiotherapy, or (2) 6 doses of C225 given both during radiotherapy and continuing for 3 additional doses after radiotherapy. Tumor cure was assessed by the radiation dose yielding local tumor control in 50% of animals (TCD{sub 50}), and time to recurrence was also determined. Results: Both treatment schedules increased radiocurability as evidenced by reductions in TCD{sub 50}, but the effect was greater when C225 was given both during and after radiotherapy. C225 reduced the TCD{sub 50} of 83.1 (73.2-124.8) Gy by radiation only to 46.2 (39.1-57.5) Gy when given during radiotherapy and to 30.8 (22.2-38.0) Gy when given during and after radiotherapy. Dose modification factors were 1.8 when C225 was given during radiotherapy and 2.7 when given both during and after radiotherapy. C225 was also effective in delaying the onset of tumor recurrences, and was more effective when given as both concurrent and maintenance therapy. Conclusions: Data showed that C225 strongly enhanced the curative effect of fractionated radiation, and its effect was greater if administration was extended beyond the end of radiotherapy. This important finding may influence future designs of clinical trials combining anti-EGFR (anti-epidermal growth factor receptor) agents with radiotherapy.

  2. The interplay between molecular layering and clustering in adsorption of gases on graphitized thermal carbon black--spill-over phenomenon and the important role of strong sites.

    PubMed

    Do, D D; Tan, S L Johnathan; Zeng, Yonghong; Fan, Chunyan; Nguyen, Van T; Horikawa, Toshihide; Nicholson, D

    2015-05-15

    We analyse in detail our experimental data, our simulation results and data from the literature, for the adsorption of argon, nitrogen, carbon dioxide, methanol, ammonia and water on graphitized carbon black (GTCB), and show that there are two mechanisms of adsorption at play, and that their interplay governs how different gases adsorb on the surface by either: (1) molecular layering on the basal plane or (2) clustering around very strong sites on the adsorbent whose affinity is much greater than that of the basal plane or the functional groups. Depending on the concentration of the very strong sites or the functional groups, the temperature and the relative strength of the three interactions, (a) fluid-strong sites (fine crevices and functional group) (F-SS), (b) fluid-basal plane (FB) and (c) fluid-fluid (FF), the uptake of adsorbate tends to be dominated by one mechanism. However, there are conditions (temperature and adsorbate) where two mechanisms can both govern the uptake. For simple gases, like argon, nitrogen and carbon dioxide, adsorption proceeds by molecular layering on the basal plane of graphene, but for water which represents an extreme case of a polar molecule, clustering around the strong sites or the functional groups at the edges of the graphene layers is the major mechanism of adsorption and there is little or no adsorption on the basal planes because the F-SS and FF interactions are far stronger than the FB interaction. For adsorptives with lower polarity, exemplified by methanol or ammonia, the adsorption mechanism switches from clustering to layering in the order: ammonia, methanol; and we suggest that the bridging between these two mechanisms is a molecular spill-over phenomenon, which has not been previously proposed in the literature in the context of physical adsorption. PMID:25660710

  3. Accelerated line-by-line calculations for the radiative transfer of trace gases related to climate studies. Progress report No. 1, 15 September 1993--14 September 1994

    SciTech Connect

    Clough, S.A.

    1993-11-15

    In the present study we are studying the effects of including carbon dioxide, ozone, methane, and the halocarbons in addition to water vapor in the radiating atmosphere. The study has focused on two principal issues: the effect on the spectral fluxes and cooling rates of carbon dioxide, ozone and the halocarbons at 1990 concentration levels and the change in fluxes and cooling rates as a consequence of the anticipated ten year change in the profiles of these species. For the latter study the water vapor profiles have been taken as invariant in time. The radiative line-by-line calculations using LBLRTM (Line-By-Line Radiative Transfer Model) have been performed for tropical (TRP), mid-latitude winter (MLW) and mid-latitude summer (MLS) model atmospheres. The halocarbons considered in the present study are CCl{sub 4}, CFC-11, CFC-12 and CFC-22. In addition to considering the radiative effects of carbon dioxide at 355 ppM, the assumed current level, we have also obtained results for doubled carbon dioxide at 710 ppM. An important focus of the current research effort is the effect of the ozone depletion profile on atmospheric radiative effects.

  4. Physical and Optical/Radiative Characteristics of Aerosol and Cloud Particles in Tropical Cirrus: Importance in Radiation Balance

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Howard, S. D.; Foster, T. C.; Hallett, J.; Arnott, W. P.; Condon, Estelle P. (Technical Monitor)

    1996-01-01

    Whether cirrus clouds heat or cool the Earth-atmosphere system depends on the relative importance of the cloud shortwave albedo effect and the cloud thermal greenhouse effect. Both are determined by the distribution of ice condensate with cloud particle size. The microphysics instrument package flown aboard the NASA DC-8 in TOGA/COARE included an ice crystal replicator, a 2D Greyscale Cloud Particle Probe and a Forward Scattering Spectrometer Aerosol Probe. In combination, the electro-optical instruments permitted particle size measurements between 0.5 micrometer and 2.6 millimeter diameter. Ice crystal replicas were used to validate signals from the electrooptical instruments. Both optical and scanning electron microscopy were utilized to analyze aerosol and ice particle replicas between 0.1 micrometer and several 100 micrometer diameter. In first approximation, the combined aerosol-cloud particle spectrum in several clouds followed a power law N alpha D(sup -2.5). Thus, large cloud particles carried most of the condensate mass, while small cloud and aerosol particles determined the surface area. The mechanism of formation of small particles is growth of (hygroscopic, possibly ocean-derived) aerosol particles along the Kohler curves. The concentration of small particles is higher and less variable in space and time, and their tropospheric residence time is longer, than those of large cloud particles because of lower sedimentation velocities. Small particles shift effective cloud particle radii to sizes much smaller than the mean diameter of the cloud particles. This causes an increase in shortwave reflectivity and IR emissivity, and a decrease in transmissivity. Occasionally, the cloud reflectivity increased with altitude (decreasing temperature) stronger than did cloud emissivity, yielding enhanced radiative cooling at higher altitudes. Thus, cirrus produced by deep convection in the tropics may be critical in controlling processes whereby energy from warm tropical oceans is injected to different levels in the atmosphere to subsequently influence not only tropical but mid-latitude climate.

  5. Linear electric field frequency shift (important for next generation electric dipole moment searches) induced in confined gases by a magnetic field gradient

    E-print Network

    Barabanov, A A L; Lamoreaux, S K; Barabanov, Authors A.L.

    2006-01-01

    The search for particle electric dipole moments (edm) represents a most promising way to search for physics beyond the standard model. A number of groups are planning a new generation of experiments using stored gases of various kinds. In order to achieve the target sensitivities it will be necessary to deal with the systematic error resulting from the interaction of the well-known $\\overrightarrow{v}\\times \\overrightarrow{E}$ field with magnetic field gradients (often referred to as the geometric phase effect (Commins, ED; Am. J. Phys. \\QTR{bf}{59}, 1077 (1991), Pendlebury, JM \\QTR{em}{et al;} Phys. Rev. \\QTR{bf}{A70}, 032102 (2004)). This interaction produces a frequency shift linear in the electric field, mimicking an edm. In this work we introduce an analytic form for the velocity auto-correlation function which determines the velocity-position correlation function which in turn determines the behavior of the frequency shift (Lamoreaux, SK and Golub, R; Phys. Rev \\QTR{bf}{A71}, 032104 (2005)) and show how...

  6. Linear electric field frequency shift (important for next generation electric dipole moment searches) induced in confined gases by a magnetic field gradient

    E-print Network

    Authors A. L. Barabanov; R. Golub; S. K. Lamoreaux

    2006-07-17

    The search for particle electric dipole moments (edm) represents a most promising way to search for physics beyond the standard model. A number of groups are planning a new generation of experiments using stored gases of various kinds. In order to achieve the target sensitivities it will be necessary to deal with the systematic error resulting from the interaction of the well-known $\\overrightarrow{v}\\times \\overrightarrow{E}$ field with magnetic field gradients (often referred to as the geometric phase effect (Commins, ED; Am. J. Phys. \\QTR{bf}{59}, 1077 (1991), Pendlebury, JM \\QTR{em}{et al;} Phys. Rev. \\QTR{bf}{A70}, 032102 (2004)). This interaction produces a frequency shift linear in the electric field, mimicking an edm. In this work we introduce an analytic form for the velocity auto-correlation function which determines the velocity-position correlation function which in turn determines the behavior of the frequency shift (Lamoreaux, SK and Golub, R; Phys. Rev \\QTR{bf}{A71}, 032104 (2005)) and show how it depends on the operating conditions of the experiment. We also discuss some additional issues.

  7. Global tropospheric chemistry models for radiatively important trace species: Design and research recommendations

    SciTech Connect

    Barchet, W.R.; Brothers, A.J.; Berkowitz, C.M.; Easter, R.C.; Ghan, S.J.; Saylor, R.D.

    1993-12-01

    Changes in the Earth`s climate could significantly affect regional and global concentrations of trace species that are criteria pollutants regulated by the US Environmental Protection Agency (EPA). The policy community also needs to know how changes in global natural and anthropogenic emissions of greenhouse gases, particulate aerosols, and aerosol precursors will affect the distribution and concentration of these pollutants. This report maps out one path for obtaining this information.

  8. TWO-DIMENSIONAL RADIATIVE MAGNETOHYDRODYNAMIC SIMULATIONS OF THE IMPORTANCE OF PARTIAL IONIZATION IN THE CHROMOSPHERE

    SciTech Connect

    Martinez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo

    2012-07-10

    The bulk of the solar chromosphere is weakly ionized and interactions between ionized particles and neutral particles likely have significant consequences for the thermodynamics of the chromospheric plasma. We investigate the importance of introducing neutral particles into the MHD equations using numerical 2.5D radiative MHD simulations obtained with the Bifrost code. The models span the solar atmosphere from the upper layers of the convection zone to the low corona, and solve the full MHD equations with non-gray and non-LTE radiative transfer, and thermal conduction along the magnetic field. The effects of partial ionization are implemented using the generalized Ohm's law, i.e., we consider the effects of the Hall term and ambipolar diffusion in the induction equation. The approximations required in going from three fluids to the generalized Ohm's law are tested in our simulations. The Ohmic diffusion, Hall term, and ambipolar diffusion show strong variations in the chromosphere. These strong variations of the various magnetic diffusivities are absent or significantly underestimated when, as has been common for these types of studies, using the semi-empirical VAL-C model as a basis for estimates. In addition, we find that differences in estimating the magnitude of ambipolar diffusion arise depending on which method is used to calculate the ion-neutral collision frequency. These differences cause uncertainties in the different magnetic diffusivity terms. In the chromosphere, we find that the ambipolar diffusion is of the same order of magnitude or even larger than the numerical diffusion used to stabilize our code. As a consequence, ambipolar diffusion produces a strong impact on the modeled atmosphere. Perhaps more importantly, it suggests that at least in the chromospheric domain, self-consistent simulations of the solar atmosphere driven by magnetoconvection can accurately describe the impact of the dominant form of resistivity, i.e., ambipolar diffusion. This suggests that such simulations may be more realistic in their approach to the lower solar atmosphere (which directly drives the coronal volume) than previously assumed.

  9. Transport fluxes and emission of greenhouse gases of the Middle Niger River (west Africa): disproprotionate importance of the recent red floods in the Niamey region

    NASA Astrophysics Data System (ADS)

    Darchambeau, François; Bouillon, Steven; Alhou, Bassirou; Lambert, Thibault; Borges, Alberto V.

    2014-05-01

    The Niger River is Africa's third longest river and drains an area of ~2,120,000 km². It encompasses six hydrographic regions and crosses almost all possible ecosystem zones in West Africa. Since few decades, the Middle Niger River presents a two flood hydrograph, the local flood, or red flood, occurring during the rainy season being the more pronounced one. Here, we report initial results of a monitoring campaign whereby 2-weekly samples were collected at Niamey (Niger) [2.01°E 13.57°N] between April 2011 and March 2013 for a suite of physico-chemical and biogeochemical characteristics, including total suspended matter (TSM) concentrations, concentration and stable isotope composition of particulate organic carbon (POC and ?13C-POC) and particulate nitrogen (PN and ?15N-PN), chromophoric dissolved organic matter (CDOM), dissolved organic carbon (DOC and ?13C-DOC), dissolved inorganic carbon (DIC and ?13C-DIC), concentration of greenhouse gases (GHGs) (CO2, CH4 and N2O), as well as major elements, total alkalinity, and oxygen isotope signatures of water (?18O-H2O). This dataset allows us to construct seasonal budgets for particulate and dissolved carbon fluxes, nutrient exports, as well as a first seasonally resolved characterisation of the GHGs emitted to the atmosphere by the Middle Niger River. The red flood, concentrated on 2 months (August-September), contributed to more than 80% of the annual transport fluxes of TSM and POC and to approximately 30% of the annual transport fluxes of DIC and DOC.

  10. Sources of black carbon aerosols in South Asia and surrounding regions during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)

    SciTech Connect

    Kumar, R.; Barth, M. C.; Nair, V. S.; Pfister, G. G.; Suresh Babu, S.; Satheesh, S. K.; Moorthy, K. Krishna; Carmichael, G. R.; Lu, Z.; Streets, D. G.

    2015-05-19

    This study examines differences in the surface black carbon (BC) aerosol loading between the Bay of Bengal (BoB) and the Arabian Sea (AS) and identifies dominant sources of BC in South Asia and surrounding regions during March–May 2006 (Integrated Campaign for Aerosols, Gases and Radiation Budget, ICARB) period. A total of 13 BC tracers are introduced in the Weather Research and Forecasting Model coupled with Chemistry to address these objectives. The model reproduced the temporal and spatial variability of BC distribution observed over the AS and the BoB during the ICARB ship cruise and captured spatial variability at the inland sites. In general, the model underestimates the observed BC mass concentrations. However, the model–observation discrepancy in this study is smaller compared to previous studies. Model results show that ICARB measurements were fairly well representative of the AS and the BoB during the pre-monsoon season. Elevated BC mass concentrations in the BoB are due to 5 times stronger influence of anthropogenic emissions on the BoB compared to the AS. Biomass burning in Burma also affects the BoB much more strongly than the AS. Results show that anthropogenic and biomass burning emissions, respectively, accounted for 60 and 37% of the average ± standard deviation (representing spatial and temporal variability) BC mass concentration (1341 ± 2353 ng m-3) in South Asia. BC emissions from residential (61%) and industrial (23%) sectors are the major anthropogenic sources, except in the Himalayas where vehicular emissions dominate. We find that regional-scale transport of anthropogenic emissions contributes up to 25% of BC mass concentrations in western and eastern India, suggesting that surface BC mass concentrations cannot be linked directly to the local emissions in different regions of South Asia.

  11. Sources of black carbon aerosols in South Asia and surrounding regions during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)

    DOE PAGESBeta

    Kumar, R.; Barth, M. C.; Nair, V. S.; Pfister, G. G.; Suresh Babu, S.; Satheesh, S. K.; Moorthy, K. Krishna; Carmichael, G. R.; Lu, Z.; Streets, D. G.

    2015-05-19

    This study examines differences in the surface black carbon (BC) aerosol loading between the Bay of Bengal (BoB) and the Arabian Sea (AS) and identifies dominant sources of BC in South Asia and surrounding regions during March–May 2006 (Integrated Campaign for Aerosols, Gases and Radiation Budget, ICARB) period. A total of 13 BC tracers are introduced in the Weather Research and Forecasting Model coupled with Chemistry to address these objectives. The model reproduced the temporal and spatial variability of BC distribution observed over the AS and the BoB during the ICARB ship cruise and captured spatial variability at the inlandmore »sites. In general, the model underestimates the observed BC mass concentrations. However, the model–observation discrepancy in this study is smaller compared to previous studies. Model results show that ICARB measurements were fairly well representative of the AS and the BoB during the pre-monsoon season. Elevated BC mass concentrations in the BoB are due to 5 times stronger influence of anthropogenic emissions on the BoB compared to the AS. Biomass burning in Burma also affects the BoB much more strongly than the AS. Results show that anthropogenic and biomass burning emissions, respectively, accounted for 60 and 37% of the average ± standard deviation (representing spatial and temporal variability) BC mass concentration (1341 ± 2353 ng m-3) in South Asia. BC emissions from residential (61%) and industrial (23%) sectors are the major anthropogenic sources, except in the Himalayas where vehicular emissions dominate. We find that regional-scale transport of anthropogenic emissions contributes up to 25% of BC mass concentrations in western and eastern India, suggesting that surface BC mass concentrations cannot be linked directly to the local emissions in different regions of South Asia.« less

  12. Biomarkers and Surrogate Endpoints for Normal-Tissue Effects of Radiation Therapy: The Importance of Dose-Volume Effects

    SciTech Connect

    Bentzen, Soren M.; Parliament, Matthew; Deasy, Joseph O.; Dicker, Adam; Curran, Walter J.; Williams, Jacqueline P.; Rosenstein, Barry S.

    2010-03-01

    Biomarkers are of interest for predicting or monitoring normal tissue toxicity of radiation therapy. Advances in molecular radiobiology provide novel leads in the search for normal tissue biomarkers with sufficient sensitivity and specificity to become clinically useful. This article reviews examples of studies of biomarkers as predictive markers, as response markers, or as surrogate endpoints for radiation side effects. Single nucleotide polymorphisms are briefly discussed in the context of candidate gene and genomewide association studies. The importance of adjusting for radiation dose distribution in normal tissue biomarker studies is underlined. Finally, research priorities in this field are identified and discussed.

  13. Present state of knowledge of the upper atmosphere: An assessment report; processes that control ozone and other climatically important trace gases

    NASA Technical Reports Server (NTRS)

    Watson, R. T.; Geller, M. A.; Stolarski, R. S.; Hampson, R. F.

    1986-01-01

    The state of knowledge of the upper atmosphere was assessed as of January 1986. The physical, chemical, and radiative processes which control the spatial and temporal distribution of ozone in the atmosphere; the predicted magnitude of ozone perturbations and climate changes for a variety of trace gas scenarios; and the ozone and temperature data used to detect the presence or absence of a long term trend were discussed. This assessment report was written by a small group of NASA scientists, was peer reviewed, and is based primarily on the comprehensive international assessment document entitled Atmospheric Ozone 1985: Assessment of Our Understanding of the Processes Controlling Its Present Distribution and Change, to be published as the World Meteorological Organization Global Ozone Research and Monitoring Project Report No. 16.

  14. Abstract-Proton Computed Tomography (CT) has important implications for both image-guided diagnosis and radiation

    E-print Network

    California at Santa Cruz, University of

    Abstract- Proton Computed Tomography (CT) has important implications for both image-guided diagnosis and radiation therapy. For diagnosis, the fact that the patient dose committed by proton CT and contrast, may be exploited in dose-critical clinical settings. Proton CT is also the most appropriate

  15. The Importance of Stellar Winds and Radiation in Massive Star Cluster Formation

    NASA Astrophysics Data System (ADS)

    Rosen, Anna

    2015-08-01

    Stellar feedback, the injection of energy and momentum by stars, remains one of the largest uncertainties in star cluster formation. Massive stars dramatically affect the surrounding interstellar medium (ISM) through a variety of feedback mechanisms including the direct and dust-reprocessed radiation pressure, and the hot gas shock-heated by stellar winds. These mechanisms can limit star formation efficiencies in massive star clusters (MSCs). For stellar winds, I discuss how we can use observations to constrain a range of kinetic energy loss channels, including radiative cooling, mechanical work on the cold ISM, thermal conduction, heating of dust via collisions by the hot gas, and bulk advection of thermal energy by the hot gas. I demonstrate that the kinetic energy injected by stellar winds is not a significant contributor to stellar feedback. I argue instead that radiation pressure is likely the dominant feedback mechanism in MSCs formed in massive, dense molecular clouds with escape speeds greater than 10 km/s, at least for the ~4 Myr before supernovae begin. Thus simulations of MSC formation require an accurate treatment of the radiation field which captures the first absorption event of stellar irradiation and also follows the diffuse dust-reprocessed radiation field. To this end, we have developed a multi-frequency hybrid radiation scheme in the astrophysical AMR code ORION to be used in such simulations.

  16. Greenhouse Gases

    MedlinePLUS

    ... is involved is critically important to projecting future climate change, but as yet is still fairly poorly measured ... feedbacks in the climate system leading to global climate change. As yet, though the basics of the hydrological ...

  17. Importance of representing optical depth variability for estimates of global line-shaped contrail radiative forcing

    PubMed Central

    Kärcher, Bernd; Burkhardt, Ulrike; Ponater, Michael; Frömming, Christine

    2010-01-01

    Estimates of the global radiative forcing by line-shaped contrails differ mainly due to the large uncertainty in contrail optical depth. Most contrails are optically thin so that their radiative forcing is roughly proportional to their optical depth and increases with contrail coverage. In recent assessments, the best estimate of mean contrail radiative forcing was significantly reduced, because global climate model simulations pointed at lower optical depth values than earlier studies. We revise these estimates by comparing the probability distribution of contrail optical depth diagnosed with a climate model with the distribution derived from a microphysical, cloud-scale model constrained by satellite observations over the United States. By assuming that the optical depth distribution from the cloud model is more realistic than that from the climate model, and by taking the difference between the observed and simulated optical depth over the United States as globally representative, we quantify uncertainties in the climate model’s diagnostic contrail parameterization. Revising the climate model results accordingly increases the global mean radiative forcing estimate for line-shaped contrails by a factor of 3.3, from 3.5 mW/m2 to 11.6 mW/m2 for the year 1992. Furthermore, the satellite observations and the cloud model point at higher global mean optical depth of detectable contrails than often assumed in radiative transfer (off-line) studies. Therefore, we correct estimates of contrail radiative forcing from off-line studies as well. We suggest that the global net radiative forcing of line-shaped persistent contrails is in the range 8–20 mW/m2 for the air traffic in the year 2000. PMID:20974909

  18. Stellar Atmospheres Near an AGN: The Importance of Radiation Pressure from Trapped Lyman-alpha Photons

    E-print Network

    Weihsueh A. Chiu; B. T. Draine

    1998-03-18

    We derive an analytic expression for the intensity of resonance-line radiation ``trapped'' in a semi-infinite medium. Given a source function and destruction probability per scattering, the radiation pressure due to trapped photons can be calculated by numerically integrating over analytic functions. We apply this formalism to a plane-parallel model stellar atmosphere to calculate the radiation pressure due to Lyman-alpha photons produced following absorption of UV and X-rays from an AGN. For low surface gravity stars near the AGN (g~10 cm/sec^2, r~0.25 pc), we find that the pressure due to Lyman-alpha photons becomes an appreciable fraction of that required for hydrostatic support. If the broad emission line emitting gas in AGNs and QSOs consists of stellar outflows, it may be driven, in part, by Lyman-alpha pressure.

  19. Blood gases

    MedlinePLUS

    ... The test also provides information about the body's acid/base balance, which can reveal important clues about lung ... Effros RM, Swenson ER. Acid-base balance. In: Mason RJ, Broaddus CV, ... Textbook of Respiratory Medicine . 5th ed. Philadelphia, PA: ...

  20. Determination of Important Nuclear Fragmentation Processes for Human Space Radiation Protection

    NASA Technical Reports Server (NTRS)

    Lin, Zi-Wei

    2007-01-01

    We present a semi-analytical method to determine which partial cross sections of nuclear fragmentations most affect the shielded dose equivalent due to exposure to galactic cosmic rays. The cross sections thus determined will require more theoretical and/or experimental studies in order for us to better predict, reduce and mitigate the radiation exposure in human space explorations.

  1. Final Technical Report for "Radiative Heating Associated with Tropical Convective Cloud Systems: Its Importance at Meso and Global Scales"

    SciTech Connect

    Schumacher, Courtney

    2012-12-13

    Heating associated with tropical cloud systems drive the global circulation. The overall research objectives of this project were to i) further quantify and understand the importance of heating in tropical convective cloud systems with innovative observational techniques, and ii) use global models to determine the large-scale circulation response to variability in tropical heating profiles, including anvil and cirrus cloud radiative forcing. The innovative observational techniques used a diversity of radar systems to create a climatology of vertical velocities associated with the full tropical convective cloud spectrum along with a dissection of the of the total heating profile of tropical cloud systems into separate components (i.e., the latent, radiative, and eddy sensible heating). These properties were used to validate storm-scale and global climate models (GCMs) and were further used to force two different types of GCMs (one with and one without interactive physics). While radiative heating was shown to account for about 20% of the total heating and did not have a strong direct response on the global circulation, the indirect response was important via its impact on convection, esp. in how radiative heating impacts the tilt of heating associated with the Madden-Julian Oscillation (MJO), a phenomenon that accounts for most tropical intraseasonal variability. This work shows strong promise in determining the sensitivity of climate models and climate processes to heating variations associated with cloud systems.

  2. Radiation track structure is not only important in determining the response of traversed cells but also non-traversed cells.

    NASA Astrophysics Data System (ADS)

    Hill, Mark

    2012-07-01

    The spatial distribution of energy deposition on the scale of DNA, cells and tissue for both low and high-LET radiation is important in determining the subsequent biological response in DNA, cells and ultimately people. In irradiated cells, the biological response has been shown to be critically dependant on the clustering of damage to DNA on the nanometre scale, with high-LET radiation not only producing a higher frequency of complex DNA damage but also typically producing damage sites of greater complexity than those produced by low-LET radiation. The differences in the energy distribution on the micron/cellular scale are also important with regards to chromosome aberration formation. The traversal of a cell by a high-LET track typically produces a non-homogeneous dose distribution through a cell nucleus and correlated DNA double-strand breaks along the path, resulting in an increased probability of complex chromosomal rearrangements (3 or more breaks in 2 or more chromosomes). In addition, in recent years it has become increasing clear that cells do not act in isolation, but the ultimate response of a cell or tissue is dependent on intercellular signalling. This becomes increasingly important at the low doses, or low dose rates, associated with typical human exposures. In order to help characterise the underlying mechanism of intercellular signalling, and how they are perturbed following exposure to ionising radiation, a previously well-defined model system of intercellular induction of apoptosis (IIA) was used, where neighbouring normal cells selectively eliminate transformed cells through cytokine (TGF-beta) and ROS/RNS signalling. The rate of apoptosis in unirradiated transformed cells was found to be enhanced even after extremely low doses of both low-LET (2 mGy gamma-rays) and high-LET (0.3 mGy alpha-particles) with the enhancement independent of dose and radiation quality at medium to high doses. The level of stimulation was found to be also dependent on the fraction of cells irradiated, cell type, levels of TGF-beta, distance between cell populations and oxygen concentration. The study shows that the stimulation of intercellular signalling by radiation required both sufficient energy deposition within irradiated cells and fraction of cells irradiated, with the response dependent on radiation quality only at low doses or when a small fraction of cells are irradiated. These results will be discussed in terms of their potential implications to risks associated with typical human exposures.

  3. Radiative properties of char, fly-ash, and soot particles in coal flames. Quarterly report No. VI, December 15, 1993--March 15, 1994

    SciTech Connect

    Manickavasagam, S.; Menguec, M.P.

    1994-09-01

    In combustion systems, particulate matter such as soot, ash, char, as well as combustion gases such as water vapor, carbon dioxide and carbon monoxide participate to radiative heat transfer. In general, the radiative properties of particles are much more important than that for combustion gases because particles absorb, emit and scatter radiation continuously in the entire wavelength spectrum. By contrast, combustion gases participate radiatively only in narrow bands centered around discrete wavelengths. The radiative properties required for typical radiative transfer calculations are absorption and scattering coefficients and scattering phase function. These properties are dependent on the partial pressures and chemical composition of combustion gases, material and physical structure, size, and volume fraction distributions of particles, and of course on the wavelength of the incident radiation. The main objective of this project is to estimate the volume fractions of combustion products by observing their scattering and absorption behaviour when subjected to external electromagnetic radiation.

  4. Emissions of biogenic sulfur gases from northern bogs and fens

    NASA Technical Reports Server (NTRS)

    Demello, William Zamboni; Hines, Mark E.; Bayley, Suzanne E.

    1992-01-01

    Sulfur gases are important components of the global cycle of S. They contribute to the acidity of precipitation and they influence global radiation balance and climate. The role of terrestrial sources of biogenic S and their effect on atmospheric chemistry remain as major unanswered questions in our understanding of the natural S cycle. The role of northern wetlands as sources and sinks of gaseous S by measuring rates of S gas exchange as a function of season, hydrologic conditions, and gradients in tropic status was investigated. Experiments were conducted in wetlands in New Hampshire, particularly a poor fen, and in Mire 239, a poor fen at the Experimental Lakes Area (ELA) in Ontario. Emissions were determined using Teflon enclosures, gas cryotrapping methods and gas chromatography (GC) with flame photometric detection. Dynamic (sweep flow) and static enclosures were employed which yielded similar results. Dissolved S gases and methane were determined by gas stripping followed by GC.

  5. The Importance of Technical Reachback in the Adjudication of Radiation Alarms

    SciTech Connect

    Buckley, W M; Allen, R W

    2009-03-18

    The large-scale deployment of radiation sensors at borders, ports-of-entry and other locations carries two disparate priorities: the reliable detection and identification of threat materials and the rapid characterization of non-threat materials comprised of naturally occurring radioactive materials (NORM) and legitimate radioactive materials in streams of commerce. These priorities are partially achieved through the technologies contained in the detection systems and the procedures developed for their operation. However, questions and ambiguities will occur. Without established capabilities and procedures for the operators of these detector systems to 'reach back' to trained spectroscopists and appropriate subject matter experts, the system will likely experience an unacceptable number of response operations and delays resolving alarms. Technical reachback operations need to be able to address the priorities discussed above while causing minimal perturbations in the flow of legitimate streams of commerce. Yet when necessary, reachback needs to be able to rapidly mobilize the appropriate response assets.

  6. Separation of polar gases from nonpolar gases

    DOEpatents

    Kulprathipanja, Santi (Hoffman Estates, IL); Kulkarni, Sudhir S. (Hoffman Estates, IL)

    1986-01-01

    Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

  7. Separation of polar gases from nonpolar gases

    DOEpatents

    Kulprathipanja, S.; Kulkarni, S.S.

    1986-08-26

    Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

  8. Separation of polar gases from nonpolar gases

    DOEpatents

    Kulprathipanja, Santi (Hoffman Estates, IL)

    1986-01-01

    The separation of polar gases from nonpolar gases may be effected by passing a mixture of nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The porous support is pretreated prior to casting of the mixture thereon by contact with a polyhydric alcohol whereby the pores of the support are altered, thus adding to the increased permeability of the polar gas.

  9. Separation of polar gases from nonpolar gases

    DOEpatents

    Kulprathipanja, S.

    1986-08-19

    The separation of polar gases from nonpolar gases may be effected by passing a mixture of nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The porous support is pretreated prior to casting of the mixture thereon by contact with a polyhydric alcohol whereby the pores of the support are altered, thus adding to the increased permeability of the polar gas.

  10. Climate-chemical interactions and greenhouse effects of trace gases

    NASA Technical Reports Server (NTRS)

    Shi, Guang-Yu; Fan, Xiao-Biao

    1994-01-01

    A completely coupled one-dimensional radiative-convective (RC) and photochemical-diffusion (PC) model has been developed recently and used to study the climate-chemical interactions. The importance of radiative-chemical interactions within the troposphere and stratosphere has been examined in some detail. We find that increases of radiatively and/or chemically active trace gases such as CO2, CH4 and N2O have both the direct effects and the indirect effects on climate change by changing the atmospheric O3 profile through their interaction with chemical processes in the atmosphere. It is also found that the climatic effect of ozone depends strongly on its vertical distribution throughout the troposphere and stratosphere, as well on its column amount in the atmosphere.

  11. Impact of greenhouse gases on the Earth's ozone layer

    NASA Astrophysics Data System (ADS)

    Zadorozhny, Alexander

    A numerical 2-D zonally averaged interactive dynamical radiative-photochemical model of the ozonosphere including aerosol physics is used to examine the role of the greenhouse gases CO2 , CH4 , and N2 O in the future long-term changes of the Earth's ozone layer, in particular in its recovery after reduction of anthropogenic discharges of chlorine and bromine compounds into the atmosphere. The model allows calculating self-consistently diabatic circulation, temperature, gaseous composition of the troposphere and stratosphere at latitudes from the South to North Poles, as well as distribution of sulphate aerosol particles and polar stratospheric clouds (PSCs) of types I and II. The scenarios of expected changes of the anthropogenic pollutants for the period from 1980 through 2050 are taken from Climate Change 2001. The processes, which determine the influence of anthropogenic growth of atmospheric abundance of the greenhouse gases on the dynamics of recovery of the Earth's ozone layer, have been studied in details. Expected cooling of the stratosphere caused by increases of greenhouse gases, most importantly CO2 , essentially influences the ozone layer by two ways: through temperature dependencies of the gas phase reaction rates and through enhancement of polar ozone depletion via increased PSC formation. The model calculations show that a weakness in efficiencies of all gas phase catalytic cycles of the ozone destruction due to cooling of the stratosphere is a dominant mechanism of the impact of the greenhouse gases on the ozone layer in Antarctic as well as at the lower latitudes. This mechanism leads to a significant acceleration of the ozone layer recovery here because of the greenhouse gases growth. On the contrary, the mechanism of the impact of the greenhouse gases on the ozone through PSC modification begins to be more effective in Arctic in comparison with the gas phase mechanism in springs after about 2020, which leads to retard the expected recovery of the ozone layer here. The mechanism of the impact of the greenhouse gases on the polar ozone by means of modification of sulphate aerosol distribution in the atmosphere has been revealed and investigated, too. Numerical experiments show that enhancement of the surface area density of sulphate aerosol in the stratosphere caused by the growth of the greenhouse gases will reduce significantly the ozone depletion during the Antarctic ozone hole.

  12. Emissions of greenhouse gases in the United States, 1985--1990

    SciTech Connect

    Not Available

    1993-11-10

    The Earth`s capacity to support life depends on the moderating influences of gases that envelop the planet and warm its surface and protect it from harmful radiation. These gases are referred to as ``greenhouse gases.`` Their warming capacity, called ``the greenhouse effect,`` is essential to maintaining a climate hospitable to all plant, animal, and human life. In recent years, however, there has been increasing concern that human activity may be affecting the intricate balance between the Earth`s absorption of heat from the sun and its capacity to reradiate excess heat back into space. Emissions of greenhouse gases from human activities may be an important mechanism that affects global climate. Thus, research is intensifying to improve our understanding of the role human activities might play in influencing atmospheric concentrations of greenhouse gases. On the basis of scientific findings of the past few decades, the US Government and the international community at large are now taking steps toward stabilizing greenhouse gas emissions. This report contributes to that process. Mandated by Congress this report provides estimates of US emissions of the principal greenhouse gases--carbon dioxide, methane, nitrous oxide, chlorofluorcarbons, carbon monoxide, nitrogen oxides, and nonmethane volatile organic compounds. Estimates are for the period 1985 to 1990. Preliminary estimates for 1991 have also been included, whenever data were available.

  13. Biologically important radiation damage in DNA. Annual progress report, May 1, 1993--January 31, 1994

    SciTech Connect

    Ward, J.F.

    1994-03-01

    Most DNA damage by the hydroxyl radical is confined to the bases, and this base damage represents an important component of locally multiply demanded sites (LMOS). The yields of the major damaged bases have been determined by gas chromatography mass spectrometry. For our propose, it was necessary to convert a known fraction of these damaged bases to strand breaks and then assay these labile sites as the increase in strand break yield over the normally observed level. Three potential agents by which this strategy of conversion of base damage to strand break could be implemented were identified in the original application: 1, Sl nuclease; 2, piperidine; and 3, base damage specific enzymes.

  14. ANALYSIS OF HISTORICAL RADIATIVELY IMPORTANT TRACE GASES (RITG) EMISSION: DEVELOPMENT OF A TRACE GAS ACCOUNTING SYSTEM (T-GAS) FOR 14 COUNTRIES

    EPA Science Inventory

    The report gives results of a Phase 2 study to (1) develop and test a carbon dioxide (CO2) emissions model for 14 countries; (2) conduct a limited test of the model's forecasting capability by estimating and comparing emissions forecasts for Poland with those developed by other m...

  15. Vitamin D Synthesis by UV Radiation: the Importance of Ozone Monitoring

    NASA Astrophysics Data System (ADS)

    Olds, W. J.; Moore, M. R.; Kimlin, M. G.

    2006-12-01

    The majority of humans rely on incidental sun exposure to maintain vitamin D sufficiency. Depending on where thresholds of vitamin D "sufficiency" are defined, it was recently stated that up to one billion people worldwide have suboptimal vitamin D levels (Bouillon, R., University of Leuven). Even in sunny southeast Queensland, the world's skin cancer capital, a 2006 study uncovered deficiency rates of up to 78% (at a threshold of 75 nmol/L of circulating 25-hydroxyvitamin D). Vitamin D regulates calcium absorption and inadequate levels are proven to result in osteomalacia, osteoporosis, rickets, bone pain and general skeletal weakness. Recent evidence also suggests vitamin D plays a preventative role in autoimmune diseases including numerous cancers, diabetes, schizophrenia, coronary heart disease, depression and other disorders. The most promising means of alleviating the worldwide burden of vitamin D deficiency seems to be by increased UV exposure. However, a much more mature understanding of UV exposures encountered in everyday life is required. This understanding is fundamentally founded in geophysics. UV exposures are strongly influenced by season/time of year, time of day, climate, location, pollution, aerosols and, importantly, ozone. In this work, we use computer simulations to obtain daily totals of vitamin D producing UV at numerous latitudes during one year. The ozone concentration is varied from 260 DU to 360 DU to determine the role of ozone variability on the ambient levels of vitamin D UV. Vitamin D synthesis is highly dependent on UVB. In our results, we demonstrate that this has important implications. Namely, vitamin D is strongly affected by ozone variability, since ozone filters UVB more strongly than UVA. Moreover, since erythema (sunburn) can occur at UVA wavelengths, ozone variation will more strongly affect vitamin D synthesis than erythema. Our results highlight that ozone monitoring is essential for understanding appropriate UV exposures for vitamin D health. We finally discuss implications for population health and how geophysics continues to play a vital role in addressing the widespread dilemma of vitamin D deficiency.

  16. The contribution from emissions of different gases to the enhanced greenhouse effect. Appendix B

    SciTech Connect

    Wigley, T.M.L.

    1993-01-01

    The main purpose of this paper is to compare the different contributions, that mankind has made to perturbing the atmosphere`s radiative balance. We have, and will continue to perturb both the balance of outgoing long-wave radiation and the balance of incoming short-wave radiation. Human activities since preindustrial times have caused a substantial enhancement of the greenhouse effect, a process involving the absorption of outgoing long-wave radiation which leads to a warming of the lower atmosphere. Because the atmosphere`s short-wave radiative balance is affected by the presence of small particles (aerosols) produced by the oxidation of sulphur compounds, anthropogenic emissions of sulphur dioxide (SO{sub 2}) have also caused a perturbation of the overall balance. The greenhouse gases we will consider are, in order of importance: carbon dioxide (CO{sub 2}), Methane (CH{sub 4}), nitrous oxide (N{sub 2}O) and the halocarbons. We use observed and model-based concentration data together with the most recent information relating concentrations to radiative forcing to estimate the individual contributions of the different gases to the changing radiative balance of the atmosphere. We also estimate the ranges of uncertainty in each of these estimates. We base all results on the 1992 IPCC emissions scenarios IS92a-f. We begin with a summary of 1990 conditions, then consider each gas separately (but lumping the halocarbons into a single group), to compare their relative importance.

  17. The use of the transmission windows of the Fabry-Perot interferometer in the detection of Raman scattered radiation from atmospheric gases.

    NASA Technical Reports Server (NTRS)

    Smith, W. H.; Barrett, J. J.

    1971-01-01

    Demonstration that the use of the Fabry-Perot interferometer as a filter with transmission windows occurring at regular intervals in wave numbers provides a highly sensitive method for detection of atmospheric gases using their rotational Raman spectra excited by a suitable laser. Some of the operating advantages include signal gains of several orders of magnitude, a simple direct interpretation of the results in terms of the density and types of the gaseous constituents, size and weight reductions from conventional apparatus, ease of operation, and relative freedom from interference from other molecules in the scattering volume. This method is compared with the techniques that have been discussed in the literature by other workers in the field.

  18. Impact of Desert Dust Radiative Forcing on Sahel Precipitation: Relative Importance of Dust Compared to Sea Surface Temperature Variations, Vegetation Changes, and

    E-print Network

    Mahowald, Natalie

    Impact of Desert Dust Radiative Forcing on Sahel Precipitation: Relative Importance of Dust The role of direct radiative forcing of desert dust aerosol in the change from wet to dry climate observed of desert dust when allowing dust to respond to changes in simulated climate, even including changes

  19. Characteristics of the evolution of a plasma generated by radiation from CW and repetitively pulsed CO2 lasers in different gases

    NASA Astrophysics Data System (ADS)

    Kanevskii, M. F.; Stepanova, M. A.

    1990-06-01

    The interaction between high-power CW and repetitively pulsed CO2 laser radiation and a low-threshold optical-breakdown plasma near a metal surface is investigated. The characteristics of the breakdown plasma are examined as functions of the experimental conditions. A qualitative analysis of the results obtained was performed using a simple one-dimensional model for laser combustion waves.

  20. Fluorinated greenhouse gases in the troposphere and stratosphere

    NASA Astrophysics Data System (ADS)

    Laube, Johannes C.; Gallacher, Eileen; Oram, David E.; Bönisch, Harald; Brenninkmeijer, Carl A. M.; Fraser, Paul J.; Röckmann, Thomas; Sturges, William T.

    2015-04-01

    Fluorinated organic trace gases in the atmosphere are almost exclusively thought to be of anthropogenic origin. In the case of fully fluorinated alkane and cycloalkane-derivatives their IR absorption features and very long atmospheric lifetimes (on the order of thousands of years) make them very strong greenhouse gases. We here present measurements of 10 of these perfluorocarbons in the UT/LS and stratosphere as derived from deployments of regular passenger aircraft (CARIBIC project, http://www.caribic-atmospheric.com/) and the high-altitude research aircraft M55 Geophysica. In combination with long-term tropospheric records obtained from the Cape Grim observatory, Tasmania, we estimate their impact on radiative forcing expressed as CO2-equivalents. As these gases have no significant sinks in the stratosphere they could also be suitable to derive an important transport diagnostic: the so-called mean age-of-air i.e. the average stratospheric transit time of an air parcel. We evaluate this possibility for all above-mentioned species and compare their characteristics with other inert species such as SF6, SF5CF3, and long-lived chlorofluorocarbons.

  1. Extended thermodynamics of dense gases

    NASA Astrophysics Data System (ADS)

    Arima, T.; Taniguchi, S.; Ruggeri, T.; Sugiyama, M.

    2012-11-01

    We study extended thermodynamics of dense gases by adopting the system of field equations with a different hierarchy structure to that adopted in the previous works. It is the theory of 14 fields of mass density, velocity, temperature, viscous stress, dynamic pressure, and heat flux. As a result, most of the constitutive equations can be determined explicitly by the caloric and thermal equations of state. It is shown that the rarefied-gas limit of the theory is consistent with the kinetic theory of gases. We also analyze three physically important systems, that is, a gas with the virial equations of state, a hard-sphere system, and a van der Waals fluid, by using the general theory developed in the former part of the present work.

  2. Evaluation of Planck mean coefficients for particle radiative properties in combustion environments

    NASA Astrophysics Data System (ADS)

    Hofgren, Henrik; Sundén, Bengt

    2014-09-01

    Thermal radiation is the dominating form of heat transfer in several combustion technologies that combust solid fuels, such as pulverized coal combustion and fixed bed combustion. The thermal radiation originates from the hot combustion gases and particles. For accurate modelling of thermal radiation in these environments the selection of the radiative transport model and radiative property model is important. Radiative property models for gases have received huge attention and several well documented models exist. For particles, soot has received considerable attention whereas other particles have not to a similar extent. The Planck mean coefficients are most commonly used to describe the radiative properties of the particles. For gases the Planck mean absorption coefficient is known to give large deviations from recognised exact models in predicting the radiative heat transfer. In this study the use of Planck mean coefficients for particles are investigated and compared to spectral models. Two particle mass size distributions of fly ash are used, representing biomass and coal combustion. The evaluation is conducted in several combustion-like test cases with both gases and particles. The evaluation shows that using Planck mean coefficients for particles, in combustion-like situations, can give large errors in predicting the radiative heat flux and especially the source term. A new weighted sum of grey gas approach is tested and evaluated. It includes both the particles and gases to better account for the non-greyness of the fly ash absorption coefficient.

  3. Evaluation of Planck mean coefficients for particle radiative properties in combustion environments

    NASA Astrophysics Data System (ADS)

    Hofgren, Henrik; Sundén, Bengt

    2015-04-01

    Thermal radiation is the dominating form of heat transfer in several combustion technologies that combust solid fuels, such as pulverized coal combustion and fixed bed combustion. The thermal radiation originates from the hot combustion gases and particles. For accurate modelling of thermal radiation in these environments the selection of the radiative transport model and radiative property model is important. Radiative property models for gases have received huge attention and several well documented models exist. For particles, soot has received considerable attention whereas other particles have not to a similar extent. The Planck mean coefficients are most commonly used to describe the radiative properties of the particles. For gases the Planck mean absorption coefficient is known to give large deviations from recognised exact models in predicting the radiative heat transfer. In this study the use of Planck mean coefficients for particles are investigated and compared to spectral models. Two particle mass size distributions of fly ash are used, representing biomass and coal combustion. The evaluation is conducted in several combustion-like test cases with both gases and particles. The evaluation shows that using Planck mean coefficients for particles, in combustion-like situations, can give large errors in predicting the radiative heat flux and especially the source term. A new weighted sum of grey gas approach is tested and evaluated. It includes both the particles and gases to better account for the non-greyness of the fly ash absorption coefficient.

  4. The Importance of Electron Source Population to the Remarkable Enhancement of Radiation belt Electrons during the October 2012 Storm

    NASA Astrophysics Data System (ADS)

    Tu, W.; Cunningham, G.; Reeves, G. D.; Chen, Y.; Henderson, M. G.; Blake, J. B.; Baker, D. N.; Spence, H.

    2013-12-01

    During the October 8-9 2012 storm, the MeV electron fluxes in the heart of the outer radiation belt are first wiped out then exhibit a three-orders-of-magnitude increase on the timescale of hours, as observed by the MagEIS and REPT instruments aboard the Van Allen Probes. There is strong observational evidence that the remarkable enhancement is due to local acceleration by chorus waves, as shown in the recent Science paper by Reeves et al.1. However, the importance of the dynamic electron source population transported in from the plasma sheet, to the observed remarkable enhancement, has not been studied. We illustrate the importance of the source population with our simulation of the event using the DREAM 3D diffusion model. Three new modifications have been implemented in the model: 1) incorporating a realistic and time-dependent low-energy boundary condition at 100 keV obtained from the MagEIS data; 2) utilizing event-specific chorus wave distributions derived from the low-energy electron precipitation observed by POES and validated against the in situ wave data from EMFISIS; 3) using an ';open' boundary condition at L*=11 and implementing electron lifetimes on the order of the drift period outside the solar-wind driven last closed drift shell. The model quantitatively reproduces the MeV electron dynamics during this event, including the fast dropout at the start of Oct. 8th, low electron flux during the first Dst dip, and the remarkable enhancement peaked at L*=4.2 during the second Dst dip. By comparing the model results with realistic source population against those with constant low-energy boundary (see figure), we find that the realistic electron source population is critical to reproduce the observed fast and significant increase of MeV electrons. 1Reeves, G. D., et al. (2013), Electron Acceleration in the Heart of the Van Allen Radiation Belts, Science, DOI:10.1126/science.1237743. Comparison between data and model results during the October 2012 storm for electrons at ?=3168 MeV/G and K=0.1 G1/2Re. Top plot is the electron phase space density data measured by the two Van Allen Probes; middle plot shows the results from the DREAM 3D diffusion model with a realistic electron source population derived from MagEIS data; and the bottom plot is the model results with a constant source population.

  5. Blood Gases Test

    MedlinePLUS

    ... used to evaluate a person's lung function and acid/base balance . They are typically ordered if someone is ... therapy. Blood gases are used to detect an acid-base imbalance, such as can occur with kidney failure , ...

  6. Strongly interacting Fermi gases

    E-print Network

    Bakr, Waseem S.

    Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly, we discuss high-precision ...

  7. Deviation from the Knudsen law on quantum gases

    SciTech Connect

    Babac, Gulru

    2014-12-09

    Gas flow in micro/nano scale systems has been generally studied for the Maxwell gases. In the limits of very low temperature and very confined domains, the Maxwellian approximation can break down and the quantum character of the gases becomes important. In these cases, Knudsen law, which is one of the important equations to analyze rarefied gas flows is invalid and should be reanalyzed for quantum gases. In this work, the availability of quantum gas conditions in the high Knudsen number cases is discussed and Knudsen law is analyzed for quantum gases.

  8. Thermodynamic models of the chemistry of lunar volcanic gases

    NASA Technical Reports Server (NTRS)

    Fegley, Bruce, Jr.

    1991-01-01

    Thermodynamic models and mass-balance arguments are used to constrain the chemistry of lunar volcanic gases. The results predict that lunar gases were dominated by reduced C and S gases such as CO, COS, CS2, S2. The more oxidized gases CO2 and SO2 were also important, but only in limited temperature ranges. Gases such as Cl2, CCl4, and CF4 were more abundant than HF and HCl, which were the two major H compounds in the lunar gases. Chlorides and fluorides were important species for transporting many volatile and ore-forming metals, and the implications for fractionating and concentrating metals into lunar ore-deposits merit further study.

  9. Latitudinal variation in ambient UV-B radiation is an important determinant of Lolium perenne forage production, quality, and digestibility.

    PubMed

    Comont, David; Winters, Ana; Gomez, Leonardo D; McQueen-Mason, Simon J; Gwynn-Jones, Dylan

    2013-05-01

    Few studies to date have considered the responses of agriculturally important forage grasses to UV-B radiation. Yet grasses such as Lolium perenne have a wide current distribution, representing exposure to a significant variation in ambient UV-B. The current study investigated the responses of L. perenne (cv. AberDart) to a simulated latitudinal gradient of UV-B exposure, representing biologically effective UV-B doses at simulated 70, 60, 50, 40, and 30° N latitudes. Aspects of growth, soluble compounds, and digestibility were assessed, and results are discussed in relation to UV-B effects on forage properties and the implications for livestock and bio-ethanol production. Aboveground biomass production was reduced by approximately 12.67% with every 1 kJ m(-2) day(-1) increase in biologically weighted UV-B. As a result, plants grown in the highest UV-B treatment had a total biomass of just 13.7% of controls. Total flavonoids were increased by approximately 76% by all UV-B treatments, while hydroxycinnamic acids increased in proportion to the UV-B dose. Conversely, the digestibility of the aboveground biomass and concentrations of soluble fructans were reduced by UV-B exposure, although soluble sucrose, glucose, and fructose concentrations were unaffected. These results highlight the capacity for UV-B to directly affect forage productivity and chemistry, with negative consequences for digestibility and bioethanol production. Results emphasize the need for future development and distribution of L. perenne varieties to take UV-B irradiance into consideration. PMID:23580749

  10. Latitudinal variation in ambient UV-B radiation is an important determinant of Lolium perenne forage production, quality, and digestibility

    PubMed Central

    Comont, David; Winters, Ana; Gomez, Leonardo D; McQueen-Mason, Simon J; Gwynn-Jones, Dylan

    2013-01-01

    Few studies to date have considered the responses of agriculturally important forage grasses to UV-B radiation. Yet grasses such as Lolium perenne have a wide current distribution, representing exposure to a significant variation in ambient UV-B. The current study investigated the responses of L. perenne (cv. AberDart) to a simulated latitudinal gradient of UV-B exposure, representing biologically effective UV-B doses at simulated 70, 60, 50, 40, and 30° N latitudes. Aspects of growth, soluble compounds, and digestibility were assessed, and results are discussed in relation to UV-B effects on forage properties and the implications for livestock and bio-ethanol production. Aboveground biomass production was reduced by approximately 12.67% with every 1 kJ m–2 day–1 increase in biologically weighted UV-B. As a result, plants grown in the highest UV-B treatment had a total biomass of just 13.7% of controls. Total flavonoids were increased by approximately 76% by all UV-B treatments, while hydroxycinnamic acids increased in proportion to the UV-B dose. Conversely, the digestibility of the aboveground biomass and concentrations of soluble fructans were reduced by UV-B exposure, although soluble sucrose, glucose, and fructose concentrations were unaffected. These results highlight the capacity for UV-B to directly affect forage productivity and chemistry, with negative consequences for digestibility and bioethanol production. Results emphasize the need for future development and distribution of L. perenne varieties to take UV-B irradiance into consideration. PMID:23580749

  11. Radiation

    Cancer.gov

    DCEG researchers carry out a broad-based research program designed to identify, understand, and quantify the risk of cancer in populations exposed to medical, occupational, or environmental radiation. They study ionizing radiation exposures (e.g., x-rays,

  12. Coupling the Mars dust and water cycles: The importance of radiative-dynamic feedbacks during northern hemisphere summer

    NASA Astrophysics Data System (ADS)

    Kahre, M. A.; Hollingsworth, J. L.; Haberle, R. M.; Wilson, R. J.

    2015-11-01

    Mars Global Climate Model (MGCM) simulations are carried out with and without cloud radiative forcing to investigate feedbacks between the dust and water cycles that contribute to the middle-atmosphere polar warming during northern hemisphere summer. Compared to the simulation without clouds, the simulation with clouds produces stronger polar warming, which is in better agreement with observations. The enhanced polar warming in the presence of cloud formation is caused by a radiative-dynamic feedback between a strengthened circulation due to cloud radiative effects, vertical dust transport, and further circulation intensification.

  13. Mechanisms and biological importance of photon-induced bystander responses: do they have an impact on low-dose radiation responses

    PubMed Central

    Tomita, Masanori; Maeda, Munetoshi

    2015-01-01

    Elucidating the biological effect of low linear energy transfer (LET), low-dose and/or low-dose-rate ionizing radiation is essential in ensuring radiation safety. Over the past two decades, non-targeted effects, which are not only a direct consequence of radiation-induced initial lesions produced in cellular DNA but also of intra- and inter-cellular communications involving both targeted and non-targeted cells, have been reported and are currently defining a new paradigm in radiation biology. These effects include radiation-induced adaptive response, low-dose hypersensitivity, genomic instability, and radiation-induced bystander response (RIBR). RIBR is generally defined as a cellular response that is induced in non-irradiated cells that receive bystander signals from directly irradiated cells. RIBR could thus play an important biological role in low-dose irradiation conditions. However, this suggestion was mainly based on findings obtained using high-LET charged-particle radiations. The human population (especially the Japanese, who are exposed to lower doses of radon than the world average) is more frequently exposed to low-LET photons (X-rays or ?-rays) than to high-LET charged-particle radiation on a daily basis. There are currently a growing number of reports describing a distinguishing feature between photon-induced bystander response and high-LET RIBR. In particular, photon-induced bystander response is strongly influenced by irradiation dose, the irradiated region of the targeted cells, and p53 status. The present review focuses on the photon-induced bystander response, and discusses its impact on the low-dose radiation effect. PMID:25361549

  14. Mechanisms of impact of greenhouse gases on the Earth's ozone layer in the Polar Regions

    NASA Astrophysics Data System (ADS)

    Zadorozhny, Alexander; Dyominov, Igor

    A numerical 2-D zonally averaged interactive dynamical radiative-photochemical model of the atmosphere including aerosol physics is used to examine the impact of the greenhouse gases CO2, CH4, and N2O on the future long-term changes of the Earth's ozone layer, in particular on its expected recovery after reduction of anthropogenic discharges of chlorine and bromine compounds into the atmosphere. The model allows calculating self-consistently diabatic circu-lation, temperature, gaseous composition of the troposphere and stratosphere at latitudes from the North to South Poles, as well as distribution of sulphate aerosol particles and polar strato-spheric clouds (PSCs) of types I and II. The scenarios of expected changes of the anthropogenic pollutants for the period from 1980 through 2050 are taken from Climate Change 2001. The processes, which determine the influence of anthropogenic growth of atmospheric abun-dance of the greenhouse gases on the long-term changes of the Earth's ozone layer in the Polar Regions, have been studied in details. Expected cooling of the stratosphere caused by increases of greenhouse gases, most importantly CO2, essentially influences the ozone layer by two ways: through temperature dependencies of the gas phase reaction rates and through enhancement of polar ozone depletion via increased PSC formation. The model calculations show that a weak-ness in efficiencies of all gas phase catalytic cycles of the ozone destruction due to cooling of the stratosphere is a dominant mechanism of the impact of the greenhouse gases on the ozone layer in Antarctic as well as at the lower latitudes. This mechanism leads to a significant acceleration of the ozone layer recovery here because of the greenhouse gases growth. On the contrary, the mechanism of the impact of the greenhouse gases on the ozone through PSC modification be-gins to be more effective in Arctic in comparison with the gas phase mechanism in springs after about 2020, which leads to retard the expected recovery of the ozone layer here. The difference in the impact of the greenhouse gases on the ozone layer at the southern and northern polar latitudes through PCS modification is determined by the difference in temperature regimes of the Polar Regions. The mechanism of the impact of the greenhouse gases on the polar ozone by means of modification of sulphate aerosol distribution in the atmosphere has been revealed and investigated, too. Numerical experiments show that enhancement of the surface area density of sulphate aerosol in the stratosphere caused by the growth of the greenhouse gases will reduce significantly the ozone depletion during the Antarctic ozone hole.

  15. EFFECTS OF INCREASED SOLAR ULTRAVIOLET RADIATION ON BIOGEOCHEMICAL CYCLES

    EPA Science Inventory

    Increases in solar UV radiation could affect terrestrial and aquatic biogeochemical cycles thus altering both sources and sinks of greenhouse and chemically important trace gases (e.g., carbon dioxide (CO2), carbon monoxide (CO), carbonyl sulfide (COS)). n terrestrial ecosystems,...

  16. Impacts of greenhouse gases and aerosol direct and indirect effects on clouds and

    E-print Network

    Dufresne, Jean-Louis

    Impacts of greenhouse gases and aerosol direct and indirect effects on clouds and radiation/C.N.R.S., Villeneuve d'Ascq, France Among anthropogenic perturbations of the Earth's atmosphere, greenhouse gases. Besides the direct impact on radiation through the greenhouse effect and scattering of sunlight

  17. Glass Membrane For Controlled Diffusion Of Gases

    DOEpatents

    Shelby, James E. (Alfred Station, NY); Kenyon, Brian E. (Pittsburgh, PA)

    2001-05-15

    A glass structure for controlled permeability of gases includes a glass vessel. The glass vessel has walls and a hollow center for receiving a gas. The glass vessel contains a metal oxide dopant formed with at least one metal selected from the group consisting of transition metals and rare earth metals for controlling diffusion of the gas through the walls of the glass vessel. The vessel releases the gas through its walls upon exposure to a radiation source.

  18. Gases in Tektite Bubbles.

    PubMed

    O'keefe, J A; Lowman, P D; Dunning, K L

    1962-07-20

    Spectroscopic analysis of light produced by electrodeless discharge in a tektite bubble showed the main gases in the bubble to be neon, helium, and oxygen. The neon and helium have probably diffused in from the atmosphere, while the oxygen may be atmospheric gas incorporated in the tektite during its formation. PMID:17801113

  19. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Characteristics of the evolution of a plasma formed by cw and pulse-periodic CO2 laser radiation in various gases

    NASA Astrophysics Data System (ADS)

    Kanevski?, M. F.; Stepanova, M. A.

    1990-06-01

    An investigation was made of the interaction between high-power cw and pulse-periodic CO2 laser radiation and a low-threshold optical breakdown plasma near a metal surface. Characteristics of the breakdown plasma were studied as a function of the experimental conditions. A qualitative analysis was made of the results using a simple one-dimensional model for laser combustion waves.

  20. Guidance Document CompressedGases

    E-print Network

    clothing. Some gases are more corrosive in the presence of water. Corrosive gases can cause rapid valves to prevent improper use. Contact department technician, the gas supplier or EHS with any questions

  1. When do plant radiations influence community assembly? The importance of historical contingency in the race for niche space.

    PubMed

    Tanentzap, Andrew J; Brandt, Angela J; Smissen, Rob D; Heenan, Peter B; Fukami, Tadashi; Lee, William G

    2015-07-01

    Plant radiations are widespread but their influence on community assembly has rarely been investigated. Theory and some evidence suggest that radiations can allow lineages to monopolize niche space when founding species arrive early into new bioclimatic regions and exploit ecological opportunities. These early radiations may subsequently reduce niche availability and dampen diversification of later arrivals. We tested this hypothesis of time-dependent lineage diversification and community dominance using the alpine flora of New Zealand. We estimated ages of 16 genera from published phylogenies and determined their relative occurrence across climatic and physical gradients in the alpine zone. We used these data to reconstruct occupancy of environmental space through time, integrating palaeoclimatic and palaeogeological changes. Our analysis suggested that earlier-colonizing lineages encountered a greater availability of environmental space, which promoted greater species diversity and occupancy of niche space. Genera that occupied broader niches were subsequently more dominant in local communities. An earlier time of arrival also contributed to greater diversity independently of its influence in accessing niche space. We suggest that plant radiations influence community assembly when they arise early in the occupancy of environmental space, allowing them to exclude later-arriving colonists from ecological communities by niche preemption. PMID:25771829

  2. Modeling TiO2 nanoparticle phototoxicity: The importance of chemical concentration, ultraviolet radiation intensity, and time

    EPA Science Inventory

    Toxicity of TiO2 nanoparticles (nano-TiO2) to aquatic organisms can be greatly increased upon the exposure to ultraviolet radiation (UV). This phenomenon has received some attention for pelagic species, however, investigations of nano-TiO2 phototoxicity in benthic organisms are s...

  3. Synthetic greenhouse gases to decline if Montreal Protocol amended

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-07-01

    The Montreal Protocol, an international treaty designed to reduce the release into the atmosphere of ozone-depleting gases such as hydrochlorofluorocarbons and chlorofluorocarbons, has been successful since its implementation in the late 1980s. However, related greenhouse gases, such as hydrofluorocarbons (HFCs), have increased in concentration in the atmosphere since then. HFCs, along with other synthetic greenhouse gases (SGHGs), account for a radiative forcing almost 20% as large as that due to the increase in carbon dioxide (CO2) since the preindustrial era.

  4. Radiative heat loss in gentoo penguin (Pygoscelis papua) adults and chicks and the importance of warm feet.

    PubMed

    Wilson, R P; Adelung, D; Latorre, L

    1998-01-01

    Adult penguins and their chicks differ considerably in their apparent body insulation. The chicks are covered in down, whereas the adults have the short, hard body feathers characteristic of the family, so mechanisms of heat loss may vary considerably between the two groups. We examined radiative heat loss by measuring body surface temperatures of gentoo penguins (Pygoscelis papua) in Antarctica. At the time the birds were considered to be in their thermoneutral zone, and there was little or no wind. Measurements of infrared emission were made on breeding adults and in large downy, and thermally independent, chicks in relation to environmental temperature. All 28 external body surface sites measured were positively correlated with ambient temperature, although there was considerable intersite variability in the relationship between site temperature and ambient temperature. Foot temperature increased most rapidly per degree ambient temperature increase, followed by the flippers, followed by the trunk. This pattern was particularly pronounced in the chicks, indicating that the exceptional heat-loss capacities of the feet may counteract for the reduced capacity of the flippers. Net heat transfer by radiation was examined using Stefan-Boltzmann's law and preliminary data on the surface area of a gentoo penguin body. This showed that between ground temperatures of 5 degrees and 15 degrees C overall heat transfer remains essentially constant, although radiative heat loss from the trunk decreases, this being counteracted by increasing heat transfer from the flippers and feet. Over the same temperature range the specific radiation heat transfer of the feet increased approximately 100 times faster per degree ambient temperature increase than did that of the flippers. This and the bimodality in foot temperature found in the study birds even under constant ambient temperatures indicate that within the thermoneutral zone heat loss by radiation in gentoo penguins is primarily executed using the feet, through which the blood circulates in pulses. PMID:9754529

  5. Advanced Global Atmospheric Gases Experiment (AGAGE)

    NASA Technical Reports Server (NTRS)

    Prinn, Ronald G.

    2001-01-01

    AGAGE comprises continuous high frequency in-situ gas chromatographic FID/ECD measurements of two biogenic/anthropogenic gases (CH4, N2O) and five anthropogenic gases (CFCl3, CF2Cl2, CH3CCl3, CF2ClCFCl2, CCl4) which are carried out at five globally distributed sites (Ireland, California, Barbados, Samoa, Tasmania). Also, high frequency in-situ gas-chromatographic mass spectrometric measurements of about 30 species including chlorofluorocarbon replacements and many natural halocarbons are made at two sites (Ireland, Tasmania), and will soon begin at the other three sites. Finally, high frequency in-situ gas chromatographic HgO-RD measurements of CO and H2 are performed at two sites (Ireland, Tasmania). The goal is quantitative determination of the sources, sinks, and circulation of these environmentally important gases.

  6. Greenhouse gases: What is their role in climate change

    SciTech Connect

    Edmonds, J.A.; Chandler, W.U. ); Wuebbles, D. )

    1990-12-01

    This paper summarizes information relevant to understanding the role of greenhouse gases in the atmosphere. It examines the nature of the greenhouse effect, the Earth's radiation budget, the concentrations of these gases in the atmosphere, how these concentrations have been changing, natural processes which regulate these concentrations of greenhouse gases, residence times of these gases in the atmosphere, and the rate of release of gases affecting atmospheric composition by human activities. We address the issue of the greenhouse effect itself in the first section. In the second section we examine trends in atmospheric concentration of greenhouse gases and emissions sources. In the third section, we examine the natural carbon cycle and its role in determining the atmospheric residence time of carbon dioxide (CO{sub 2}). In the fourth section, we examine the role atmospheric chemistry plays in the determining the concentrations of greenhouse gases. This paper is not intended to be an exhaustive treatment of these issues. Exhaustive treatments can be found in other volumes, many of which are cited throughout this paper. Rather, this paper is intended to summarize some of the major findings, unknowns, and uncertainties associated with the current state of knowledge regarding the role of greenhouse gases in the atmosphere. 57 refs., 11 figs., 11 tabs.

  7. A generic biokinetic model for noble gases with application to radon.

    PubMed

    Leggett, Rich; Marsh, James; Gregoratto, Demetrio; Blanchardon, Eric

    2013-06-01

    To facilitate the estimation of radiation doses from intake of radionuclides, the International Commission on Radiological Protection (ICRP) publishes dose coefficients (dose per unit intake) based on reference biokinetic and dosimetric models. The ICRP generally has not provided biokinetic models or dose coefficients for intake of noble gases, but plans to provide such information for (222)Rn and other important radioisotopes of noble gases in a forthcoming series of reports on occupational intake of radionuclides (OIR). This paper proposes a generic biokinetic model framework for noble gases and develops parameter values for radon. The framework is tailored to applications in radiation protection and is consistent with a physiologically based biokinetic modelling scheme adopted for the OIR series. Parameter values for a noble gas are based largely on a blood flow model and physical laws governing transfer of a non-reactive and soluble gas between materials. Model predictions for radon are shown to be consistent with results of controlled studies of its biokinetics in human subjects. PMID:23612507

  8. Kinetic Theory of Gases

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The theory, developed in the nineteenth century, notably by Rudolf Clausius (1822-88) and James Clerk Maxwell (1831-79), that the properties of a gas (temperature, pressure, etc) could be described in terms of the motions (and kinetic energy) of the molecules comprising the gases. The theory has wide implications in astrophysics. In particular, the perfect gas law, which relates the pressure, vol...

  9. Line-driven disk winds in active galactic nuclei: The critical importance of ionization and radiative transfer

    SciTech Connect

    Higginbottom, Nick; Knigge, Christian; Matthews, James H.; Proga, Daniel; Long, Knox S.; Sim, Stuart A.

    2014-07-01

    Accretion disk winds are thought to produce many of the characteristic features seen in the spectra of active galactic nuclei (AGNs) and quasi-stellar objects (QSOs). These outflows also represent a natural form of feedback between the central supermassive black hole and its host galaxy. The mechanism for driving this mass loss remains unknown, although radiation pressure mediated by spectral lines is a leading candidate. Here, we calculate the ionization state of, and emergent spectra for, the hydrodynamic simulation of a line-driven disk wind previously presented by Proga and Kallman. To achieve this, we carry out a comprehensive Monte Carlo simulation of the radiative transfer through, and energy exchange within, the predicted outflow. We find that the wind is much more ionized than originally estimated. This is in part because it is much more difficult to shield any wind regions effectively when the outflow itself is allowed to reprocess and redirect ionizing photons. As a result, the calculated spectrum that would be observed from this particular outflow solution would not contain the ultraviolet spectral lines that are observed in many AGN/QSOs. Furthermore, the wind is so highly ionized that line driving would not actually be efficient. This does not necessarily mean that line-driven winds are not viable. However, our work does illustrate that in order to arrive at a self-consistent model of line-driven disk winds in AGN/QSO, it will be critical to include a more detailed treatment of radiative transfer and ionization in the next generation of hydrodynamic simulations.

  10. Measuring fraction of intercepted photosynthetically active radiation with a ceptometer: the importance of adopting a universal methodological approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is desirable to be able to predict above ground biomass production indirectly, without extensive sampling or destructive harvesting. Leaf area index (LAI) is the amount of leaf surface area per ground area and is an important parameter in ecophysiology. As LAI increases, the photosynthetically ...

  11. Advanced Global Atmospheric Gases Experiment (AGAGE)

    NASA Technical Reports Server (NTRS)

    Prinn, Ronald G.; Kurylo, Michael (Technical Monitor)

    2004-01-01

    We seek funding from NASA for the third year (2005) of the four-year period January 1, 2003 - December 31, 2006 for continued support of the MIT contributions to the multi-national global atmospheric trace species measurement program entitled Advanced Global Atmospheric Gases Experiment (AGAGE). The case for real-time high-frequency measurement networks like AGAGE is very strong and the observations and their interpretation are widely recognized for their importance to ozone depletion and climate change studies and to verification issues arising from the Montreal Protocol (ozone) and Kyoto Protocol (climate). The proposed AGAGE program is distinguished by its capability to measure over the globe at high frequency almost all of the important species in the Montreal Protocol and almost all of the significant non-CO2 gases in the Kyoto Protocol.

  12. The Importance of the Montreal Protocol in Protecting Earth's Hydroclimate Courant Institute of Mathematical Sciences, New York University, New York, New York

    E-print Network

    Biasutti, Michela

    The Importance of the Montreal Protocol in Protecting Earth's Hydroclimate YUTIAN WU Courant Montreal Protocol regulating emissions of chlorofluorocarbons (CFCs) and other ozone- depleting substances that the Montreal Protocol has helped reduce radiative forcing of the climate system since CFCs are greenhouse gases

  13. Radiation Is an Important Component of Multimodality Therapy for Pediatric Non-Pineal Supratentorial Primitive Neuroectodermal Tumors

    SciTech Connect

    McBride, Sean M.; Daganzo, Sally M.; Banerjee, Anuradha; Gupta, Nalin; Lamborn, Kathleen R.; Prados, Michael D.; Berger, Mitchel S.; Wara, William M.; Haas-Kogan, Daphne A.

    2008-12-01

    Purpose: To review a historical cohort of pediatric patients with supratentorial primitive neuroectodermal tumors (sPNET), to clarify the role of radiation in the treatment of these tumors. Patients and Methods: Fifteen children aged <18 years with non-pineal sPNETs diagnosed between 1992 and 2006 were identified. Initial therapy consisted of surgical resection and chemotherapy in all patients and up-front radiotherapy (RT) in 5 patients. Five patients had RT at the time of progression, and 5 received no RT whatever. Kaplan-Meier estimates of overall survival were then calculated. Results: The median follow-up from diagnosis for all patients was 31 months (range, 0.5-165 months) and for surviving patients was 49 months (range, 10-165). Of the 5 patients who received up-front RT, all were alive without evidence of disease at a median follow-up of 50 months (range, 25-165 months). Only 5 of the 10 patients who did not receive up-front RT were alive at last follow-up. There was a statistically significant difference in overall survival between the patient group that received up-front RT and the group that did not (p = 0.048). In addition, we found a trend toward a statistically significant improvement in overall survival for those patients who received gross total resections (p = 0.10). Conclusions: Up-front RT and gross total resection may confer a survival benefit in patients with sPNET. Local failure was the dominant pattern of recurrence. Efforts should be made to determine patients most likely to have local failure exclusively or as a first recurrence, in order to delay or eliminate craniospinal irradiation.

  14. Climate-chemical interactions and effects of changing atmospheric trace gases

    NASA Technical Reports Server (NTRS)

    Ramanathan, V.; Callis, L.; Cess, R.; Hansen, J.; Isaksen, I.

    1987-01-01

    The paper considers trace gas-climate effects including the greenhouse effect of polyatomic trace gases, the nature of the radiative-chemical interactions, and radiative-dynamical interactions in the stratosphere, and the role of these effects in governing stratospheric climate change. Special consideration is given to recent developments in the investigations of the role of oceans in governing the transient climate responses, and a time-dependent estimate of the potential trace gas warming from the preindustrial era to the early 21st century. The importance of interacting modeling and observational efforts is emphasized. One of the problems remaining on the observational front is the lack of certainty in current estimates of the rate of growth of CO, O3, and NOx; the primary challenge is the design of a strategy that will minimize the sampling errors.

  15. Monitoring greenhouse gases with astronomical observations

    NASA Astrophysics Data System (ADS)

    Kausch, W.; Noll, S.; Barden, M.; Smette, A.; Szyszka, C.; Jones, A.; Kimeswenger, S.; Sana, H.; Horst, H.

    2012-04-01

    Modern telescopes are equipped with high-precision multi-mode spectrographs. To obtain proper calibration, astronomers observe the plain night sky and specific telluric standard stars (TS stars) to estimate the influence of the Earth atmosphere on astronomical observations. TS stars are usually white dwarfs, as their spectra are not time dependent and hardly contain any spectral features. Since the atmospheric emission in the thermal infrared and the absorption of stellar radiation reflect molecular abundances in the lower atmosphere, plain night sky and TS spectra can be used to obtain column densities of greenhouse gases. We present a method for determining this, incorporating the radiative transfer code LBLRTM and the HITRAN database. We fit specific molecular absorption and emission features by varying the corresponding abundance profiles iteratively implementing a Levenberg-Marquardt ?2 minimisation algorithm. This method was originally developed to estimate the amount of precipitable water vapour, which strongly influences infrared observations, above the observing site of the ESO Very Large Telescope, Cerro Paranal. We are currently in the process of extending this procedure to other greenhouse gases. As plain sky and TS stars are observed several times per night these spectra can be used to monitor molecular column densities on a long term basis.

  16. Degenerate quantum gases of strontium

    E-print Network

    Stellmer, Simon; Killian, Thomas C

    2013-01-01

    Degenerate quantum gases of alkaline-earth-like elements open new opportunities in research areas ranging from molecular physics to the study of strongly correlated systems. These experiments exploit the rich electronic structure of these elements, which is markedly different from the one of other species for which quantum degeneracy has been attained. Specifically, alkaline-earth-like atoms, such as strontium, feature metastable triplet states, narrow intercombination lines, and a non-magnetic, closed-shell ground state. This review covers the creation of quantum degenerate gases of strontium and the first experiments performed with this new system. It focuses on laser-cooling and evaporation schemes, which enable the creation of Bose-Einstein condensates and degenerate Fermi gases of all strontium isotopes, and shows how they are used for the investigation of optical Feshbach resonances, the study of degenerate gases loaded into an optical lattice, as well as the coherent creation of Sr_2 molecules.

  17. Impact of rising greenhouse gases on mid-latitude storm tracks and associated hydroclimate variability and change

    SciTech Connect

    Seager, Richard

    2014-12-08

    Project Summary This project aimed to advance physical understanding of how and why the mid-latitude jet streams and storm tracks shift in intensity and latitude in response to changes in radiative forcing with an especial focus on rising greenhouse gases. The motivation, and much of the work, stemmed from the importance that these mean and transient atmospheric circulation systems have for hydroclimate. In particular drying and expansion of the subtropical dry zones has been related to a poleward shift of the mid-latitude jets and storm tracks. The work involved integrated assessment of observation and model projections as well as targeted model simulations.

  18. On the cause of the relative greenhouse strength of gases such as the halocarbons

    SciTech Connect

    Shine, K.P. )

    1991-06-15

    This note examines some of the factors important in determining the large radiative impact, relative to carbon dioxide, of increased concentrations of gases in the optically thin limit (such as the halocarbons at their present day concentrations). A narrow-band radiative transfer model is used to show that an absorber with the same integrated band strength as CFC-12, but with almost the same spectral variation of tropopause net flux change as occurs for small variations in carbon dioxide concentration, is 400 times more effective than carbon dioxide, on a molecule-per-molecule basis; this can be compared with the relative strength of 20,000 for CFC-12. This illustrates that the dominant reason for the relative strength of such gases is not their position in the 8-13 [mu]m window. It is not possible to unambiguously separate the possible reasons (spectral position, preexisting amounts and spectroscopic strength) for the variations in relative strength, as they are all related. 9 refs., 6 figs.

  19. Atmospheric Radiation Measurement Program facilities newsletter, July 2001.

    SciTech Connect

    Holdridge, D. J.

    2001-07-23

    Global Warming and Methane--Global warming, an increase in Earth's near-surface temperature, is believed to result from the buildup of what scientists refer to as ''greenhouse gases.'' These gases include water vapor, carbon dioxide, methane, nitrous oxide, ozone, perfluorocarbons, hydrofluoro-carbons, and sulfur hexafluoride. Greenhouse gases can absorb outgoing infrared (heat) radiation and re-emit it back to Earth, warming the surface. Thus, these gases act like the glass of a greenhouse enclosure, trapping infrared radiation inside and warming the space. One of the more important greenhouse gases is the naturally occurring hydrocarbon methane. Methane, a primary component of natural gas, is the second most important contributor to the greenhouse effect (after carbon dioxide). Natural sources of methane include wetlands, fossil sources, termites, oceans, fresh-waters, and non-wetland soils. Methane is also produced by human-related (or anthropogenic) activities such as fossil fuel production, coal mining, rice cultivation, biomass burning, water treatment facilities, waste management operations and landfills, and domesticated livestock operations (Figure 1). These anthropogenic activities account for approximately 70% of the methane emissions to the atmosphere. Methane is removed naturally from the atmosphere in three ways. These methods, commonly referred to as sinks, are oxidation by chemical reaction with tropospheric hydroxyl ion, oxidation within the stratosphere, and microbial uptake by soils. In spite of their important role in removing excess methane from the atmosphere, the sinks cannot keep up with global methane production. Methane concentrations in the atmosphere have increased by 145% since 1800. Increases in atmospheric methane roughly parallel world population growth, pointing to anthropogenic sources as the cause (Figure 2). Increases in the methane concentration reduce Earth's natural cooling efficiency by trapping more of the outgoing terrestrial infrared radiation, increasing the near-surface temperature.

  20. The Importance of Physical Models for Deriving Dust Masses and Grain Size Distributions in Supernova Ejecta. I. Radiatively Heated Dust in the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Temim, Tea; Dwek, Eli

    2013-01-01

    Recent far-infrared (IR) observations of supernova remnants (SNRs) have revealed significantly large amounts of newly condensed dust in their ejecta, comparable to the total mass of available refractory elements. The dust masses derived from these observations assume that all the grains of a given species radiate at the same temperature, regardless of the dust heating mechanism or grain radius. In this paper, we derive the dust mass in the ejecta of the Crab Nebula, using a physical model for the heating and radiation from the dust. We adopt a power-law distribution of grain sizes and two different dust compositions (silicates and amorphous carbon), and calculate the heating rate of each dust grain by the radiation from the pulsar wind nebula. We find that the grains attain a continuous range of temperatures, depending on their size and composition. The total mass derived from the best-fit models to the observed IR spectrum is 0.019-0.13 Solar Mass, depending on the assumed grain composition. We find that the power-law size distribution of dust grains is characterized by a power-law index of 3.5-4.0 and a maximum grain size larger than 0.1 micron. The grain sizes and composition are consistent with what is expected for dust grains formed in a Type IIP supernova (SN). Our derived dust mass is at least a factor of two less than the mass reported in previous studies of the Crab Nebula that assumed more simplified two-temperature models. These models also require a larger mass of refractory elements to be locked up in dust than was likely available in the ejecta. The results of this study show that a physical model resulting in a realistic distribution of dust temperatures can constrain the dust properties and affect the derived dust masses. Our study may also have important implications for deriving grain properties and mass estimates in other SNRs and for the ultimate question of whether SNe are major sources of dust in the Galactic interstellar medium and in external galaxies.

  1. THE IMPORTANCE OF PHYSICAL MODELS FOR DERIVING DUST MASSES AND GRAIN SIZE DISTRIBUTIONS IN SUPERNOVA EJECTA. I. RADIATIVELY HEATED DUST IN THE CRAB NEBULA

    SciTech Connect

    Temim, Tea; Dwek, Eli

    2013-09-01

    Recent far-infrared (IR) observations of supernova remnants (SNRs) have revealed significantly large amounts of newly condensed dust in their ejecta, comparable to the total mass of available refractory elements. The dust masses derived from these observations assume that all the grains of a given species radiate at the same temperature, regardless of the dust heating mechanism or grain radius. In this paper, we derive the dust mass in the ejecta of the Crab Nebula, using a physical model for the heating and radiation from the dust. We adopt a power-law distribution of grain sizes and two different dust compositions (silicates and amorphous carbon), and calculate the heating rate of each dust grain by the radiation from the pulsar wind nebula. We find that the grains attain a continuous range of temperatures, depending on their size and composition. The total mass derived from the best-fit models to the observed IR spectrum is 0.019-0.13 M{sub Sun }, depending on the assumed grain composition. We find that the power-law size distribution of dust grains is characterized by a power-law index of 3.5-4.0 and a maximum grain size larger than 0.1 {mu}m. The grain sizes and composition are consistent with what is expected for dust grains formed in a Type IIP supernova (SN). Our derived dust mass is at least a factor of two less than the mass reported in previous studies of the Crab Nebula that assumed more simplified two-temperature models. These models also require a larger mass of refractory elements to be locked up in dust than was likely available in the ejecta. The results of this study show that a physical model resulting in a realistic distribution of dust temperatures can constrain the dust properties and affect the derived dust masses. Our study may also have important implications for deriving grain properties and mass estimates in other SNRs and for the ultimate question of whether SNe are major sources of dust in the Galactic interstellar medium and in external galaxies.

  2. EDITORIAL: Cold Quantum GasesEditorial: Cold Quantum Gases

    NASA Astrophysics Data System (ADS)

    Vassen, W.; Hemmerich, A.; Arimondo, E.

    2003-04-01

    This Special Issue of Journal of Optics B: Quantum and Semiclassical Optics brings together the contributions of various researchers working on theoretical and experimental aspects of cold quantum gases. Different aspects of atom optics, matter wave interferometry, laser manipulation of atoms and molecules, and production of very cold and degenerate gases are presented. The variety of subjects demonstrates the steadily expanding role associated with this research area. The topics discussed in this issue, extending from basic physics to applications of atom optics and of cold atomic samples, include: bulletBose--Einstein condensation bulletFermi degenerate gases bulletCharacterization and manipulation of quantum gases bulletCoherent and nonlinear cold matter wave optics bulletNew schemes for laser cooling bulletCoherent cold molecular gases bulletUltra-precise atomic clocks bulletApplications of cold quantum gases to metrology and spectroscopy bulletApplications of cold quantum gases to quantum computing bulletNanoprobes and nanolithography. This special issue is published in connection with the 7th International Workshop on Atom Optics and Interferometry, held in Lunteren, The Netherlands, from 28 September to 2 October 2002. This was the last in a series of Workshops organized with the support of the European Community that have greatly contributed to progress in this area. The scientific part of the Workshop was managed by A Hemmerich, W Hogervorst, W Vassen and J T M Walraven, with input from members of the International Programme Committee who are listed below. The practical aspects of the organization were ably handled by Petra de Gijsel from the Vrije Universiteit in Amsterdam. The Workshop was funded by the European Science Foundation (programme BEC2000+), the European Networks 'Cold Quantum Gases (CQG)', coordinated by E Arimondo, and 'Cold Atoms and Ultraprecise Atomic Clocks (CAUAC)', coordinated by J Henningsen, by the German Physical Society (DFG), by the Dutch Foundation for Fundamental Research on Matter (FOM) and by the Dutch Gelderland province. We thank all these sponsors and the members of the International Programme Committee for making the Workshop such a success. At this point we take the opportunity to express our gratitude to both authors and reviewers, for their efforts in preparing and ensuring the high quality of the papers in this special issue. Wim Vassen Vrije Universiteit, Amsterdam Andreas Hemmerich Universität Hamburg Ennio Arimondo Università di Pisa Guest Editors International Programme Committee A Aspect Orsay, France E Cornell Boulder, USA W Ertmer Hannover, Germany T W Haensch Munich, Germany A Hemmerich Hamburg, Germany W Hogervorst Amsterdam, The Netherlands D Kleppner Cambridge, USA C Salomon Paris, France G V Shlyapnikov Amsterdam, Paris, Moscow S Stringari Trento, Italy W Vassen Amsterdam, The Netherlands J T M Walraven Amsterdam, The Netherlands

  3. Mixture Working Gases in Thermoacoustic Engines for Different Applications

    NASA Astrophysics Data System (ADS)

    Ke, Hanbing; He, Yaling; Liu, Yingwen; Cui, Fuqing

    2012-07-01

    For working gases in thermoacoustic engines, the most important characteristics are low Prandtl number and high ratio of specific heats. These properties change a lot with pressure for some gases, which makes selecting a working gas under high pressure different from that under normal pressure. This article presents optimization calculations for gas mixtures under different pressures. Results show that binary mixtures of helium and xenon can reach the lowest Prandtl number and highest ratio of specific heats when the pressure is lower than 4.5MPa. When the pressure is higher than 4.5MPa, however, the lowest Prandtl number is obtained with a mixture of helium and krypton. It is found that ternary mixtures may be better working gases than binary mixtures in thermoacoustic engines, especially under high pressure. For example, a helium-argon-xenon ternary mixture can be used to obtain a relatively low Prandtl number and high ratio of specific heats. In addition, this article shows that mixtures containing carbon dioxide and other gases can also result in useful working gases. This suggests that it is possible to replace the expensive xenon gas with cheap carbon dioxide for some applications. Finally, the effect of temperature on the Prandtl number, the ratio of specific heats, and the thermal penetration depth is also studied, and a more reasonable construction of the thermoacoutic couple is presented. The results of this study should be useful for helping select working gases in thermoacoustic engines for different applications and design goals.

  4. The strange gases of Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Noll, Keith S.

    1990-01-01

    The various gases found in the atmospheres of Jupiter and Saturn are discussed. A history of scientific investigation of these planets is outlined and results of these discoveries are considered. The molecular species found in these two planets are classified into several groups. The first group consists of H2, He, CH4, NH3, and H2O while the second group contains gases formed as the chemical byproducts of solar radiation, including simple hydrocarbons such as C2H2 and C2H6 and charged particles such as H3(+). The last group contains compounds which are chemically unstable in parts of Jupiter's atmosphere that have been probed and include Ge and As; two elements usually found in minerals on earth. An investigation of origin of these elements which are currently part of the upper reaches of the atmosphere of Jupiter and Saturn has led to discoveries about much deeper and hotter parts of atmospheres that can never be observed directly. A number of hypotheses are presented to account for the presence of various unexpected compounds, such as carbon monoxide.

  5. Radiative interactions in nonequilibrium flows

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Chandrasekhar, R.

    1992-01-01

    The influence of vibrational and chemical nonequilibrium upon infrared radiative energy transfer in nonisothermal gases is investigated. Essential information is provided on rate equations, relaxation times, transfer equations, band absorption, and radiative flux equations. The methodology developed is applied to three specific cases. These are, absorbing-emitting species between isothermal parallel plates, radiating gases in the earth's atmosphere, and supersonic flow of premixed hydrogen and air in an expanding nozzle. The results obtained for different cases reveal that the extent of radiative interactions is reduced significantly under nonequilibrium conditions. The method developed can be easily extended to investigate radiative interactions in complex nonequilibrium flows.

  6. Isothermal compressors for process gases

    SciTech Connect

    Wiederuh, E.; Meinhart, D. )

    1992-09-01

    This paper reports on isothermal compressors which are more efficient for all gases. The study of several representative gases considered stage efficiencies, pressure ratios and pressure losses of the intercoolers. Generally there are two ways to reduce power consumption of a gas compression process: minimize losses of the compressor or improve the thermodynamics of the process. But there are some new ways to reduce losses of turbocompressors. Losses of the impeller labyrinth seals and the balance piston labyrinth seal can be reduced by optimizing the labyrinth geometry and minimizing labyrinth clearances. Therefore, conventional labyrinth seals are still being studied and will be improved.

  7. Quantum Gases in Optical Lattices

    NASA Astrophysics Data System (ADS)

    Barmettler, Peter; Kollath, Corinna

    2015-09-01

    The experimental realization of correlated quantum phases with ultracold gases in optical lattices and their theoretical understanding has witnessed remarkable progress during the last decade. In this review we introduce basic concepts and tools to describe the many-body physics of quantum gases in optical lattices. This includes the derivation of effective lattice Hamiltonians from first principles and an overview of the emerging quantum phases. Additionally, state-of-the-art numerical tools to quantitatively treat bosons or fermions on different lattices are introduced.

  8. Quantum Degenerate Gases of Strontium

    NASA Astrophysics Data System (ADS)

    Desalvo, Brian; Martinez de Escobar, Natali; Mickelson, Pacal; Yan, Mi; Killian, Thomas

    2010-03-01

    We have produced quantum degenerate gases of three of the four stable isotopes of strontium. Using two-stage laser trapping and cooling followed by direct evaporative cooling in a far-off- resonance optical dipole trap (ODT), a stable Bose-Einstein Condensate (BEC) of ^84Sr is formed. Via dual species trapping and sympathetic cooling in an ODT, an attractive BEC of ^88Sr is created, as well as a degenerate Fermi gas of ^87Sr. Differences in the evaporation scheme used to reach degeneracy for each isotope will be presented as well as the varied dynamics of the gases.

  9. Dust extraction from hot gases

    SciTech Connect

    Rennhack, R.

    1982-07-01

    The introduction of new energy-saving and low-pollution technologies requires development of highly efficient systems for purifying dust-laden hot gases at temperatures between 400 and 1000/sup 0/C and pressures between 1 and 20 bar. The present state of dust removal is described for separators utilizing mechanical forces, electrical effects, filtration, and wet techniques. Typical applications of present-day dust extraction from hot gases are presented. Possible developments with a view to extending the scope of dust extraction are indicated.

  10. Reactive Uptake of Acidic Gases On Mineral Aerosols

    NASA Astrophysics Data System (ADS)

    Adams, J.; Cox, R.; Griffiths, P.; Stewart, D.

    A significant proportion of tropospheric aerosols are mineral in nature. These aerosols are emitted into the atmosphere by the action of surface winds on dry soils in arid regions, by human disturbance of the earth's surface and by industrial processes, e.g. fly ash. In providing a surface for heterogeneous reactions, mineral aerosols play a role in tropospheric oxidative cycles and also affect the atmospheric radiation balance, both directly through scattering and absorption of radiation and indirectly by providing condensation and ice nuclei. Calcite (CaCO3) is an important component of mineral aerosols, for instance, forming up to 30% of Saharan dust. We have investigated three aspects of the interaction of tropospheric trace gases with Calcite surfaces, using a suite of experimental techniques. These aspects are: 1) The amount of water present on the aerosols surface may affect its reactivity. We have determined the surface loading of water on a Calcite surface as a function of relative humidity, using a surface acoustic wave sensor. 2) The scavenging of SO2 by mineral aerosols could lead to a significant repartitioning of tropospheric sulphate. We have investigated the uptake and reaction of SO2 onto CaCO3 surfaces at various relative humidities, using a coated-wall flow -tube interfaced to a electron impact mass spectrometer. 3) The heterogeneous conversion of N2O5 to HNO3 forms a step in the process, which ultimately facilitates the conversion of NOx to NO3. We- have investigated the uptake and reaction of N2O5 onto Calcite aerosols, in an atmospheric-pressure flow-tube interfaced to a NOx detector. The results of these measurements will be presented.

  11. Greenhouse effect of chlorofluorocarbons and other trace gases

    NASA Technical Reports Server (NTRS)

    Hansen, James; Lacis, Andrew; Prather, Michael

    1989-01-01

    A comparison is made of the radiative (greenhouse) forcing of the climate system due to changes of atmospheric chlorofluorocarbons and other trace gases. It is found that CFCs, defined to include chlorofluorocarbons, chlorocarbons, and fluorocarbons, now provide about one-quater of current annual increases in anthropogenic greenhouse climate forcing. If the growth rates of CFC production in the early 1970s had continued to the present, current annual growth of climate forcing due to CFCs would exceed that due to CO2.

  12. Atmospheric Concentrations of Greenhouse Gases

    EPA Science Inventory

    This indicator presents trends in atmospheric concentrations of several greenhouse gases (GHGs) over geological time and in recent years. Changes in atmospheric GHGs, in part caused by human activities, affect the amount of energy held in the Earth-atmosphere system and thus a...

  13. New frontiers with ultracold gases

    SciTech Connect

    Ketterle, Wolfgang

    2005-05-05

    This article summarizes recent work at MIT, which was presented at ICAP 2004. These examples demonstrate the broad range of topics, which are covered by research on quantum-degenerate gases: boson and fermion mixtures, cold molecules, vortices, and interactions with surfaces.

  14. Interaction quenches of Fermi gases

    SciTech Connect

    Uhrig, Goetz S.

    2009-12-15

    It is shown that the jump in the momentum distribution of Fermi gases evolves smoothly for small and intermediate times once an interaction between the fermions is suddenly switched on. The jump does not vanish abruptly. The loci in momentum space where the jumps occur are those of the noninteracting Fermi sea. No relaxation of the Fermi surface geometry takes place.

  15. Soil and litter exchange of reactive trace gases

    EPA Science Inventory

    The soil and litter play an important role in the exchange of trace gases between terrestrial ecosystems and the atmosphere. - The exchange of ammonia between vegetation and the atmosphere is highly influenced by soil and litter emissions especially in managed ecosystems (grassla...

  16. Rare gases systematics and mantle structure

    NASA Technical Reports Server (NTRS)

    Allegre, C. J.; Staudacher, T.

    1994-01-01

    The following points are emphasized: one of the most important ones is certainly the first set of experimental data on the solubility of noble gases in metal phases at intermediate pressures, since the core was certainly not formed at ultra high pressures, as emphasized by Ahrens and confirmed by trace elements systematics Wanke. The experimental data clearly show that the core can not be a major reservoir for terrestrial rare gases; the second point is a more elaborate reconsideration of the (40)K-(40)Ar budget of the Earth. This shows that (40)Ar contained in continental crust plus upper mantle plus atmosphere is at maximum half of the (40)Ar inventory of the whole earth. This implies the existence of a two layered mantle; the third point is the discovery by the Australian noble gases group of the existence of high (20)Ne/(22)Ne and low (21)Ne/(22)Ne isotopic ratios in Loihi seamount samples. This results which are different to the MORB ratios confirm the idea of a two layered model, but suggest the existence of a primordial solar type Ne reservoir. Several possibilities about the origin of this (20)Ne excess in the mantle will be discussed; The high (40)Ar/(36)Ar, (129)Xe/(130)Xe and (134) Xe/(130)Xe, (136)Xe/(130)Xe are confirmed by new data. The corresponding ratios for the lower mantle will be discussed. (40)Ar/(36)Ar ratios up to 6000 can be accepted and will not modify the general model of the mantle. They confirm the atmosphere chronology, about 85 percent of the atmosphere was formed in the first 50 My and 15 percent later on.

  17. Statistics of electron avalanches and bursts in low pressure gases below the breakdown voltage

    SciTech Connect

    Donko, Z.

    1995-12-31

    Avalanches in different types of dynamical systems have been subject of recent interest. Avalanches building up in gases play an important role in radiation detectors and in the breakdown process of gas discharges. We have used computer simulation to study statistical properties of electron avalanches and bursts (sequences of avalanches) in a gas subjected to a homogeneous electric field. Helium was used as buffer gas, but we believe that our results are more general. The bursts were initiated by injecting low energy electrons into the gas. We applied Monte Carlo procedure to trace the trajectories of electrons. The elementary processes considered in the model were anisotropic elastic scattering of electrons from He atoms, electron impact excitation and ionization of He atoms. The electrons were traced until the are reached the perfectly absorbing anode.

  18. 40 CFR 92.112 - Analytical gases.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... grade nitrogen as the diluent. (b) Gases for the hydrocarbon analyzer shall be single blends of propane... check gases shall contain propane at a concentration greater than 50 percent of range. The...

  19. 40 CFR 92.112 - Analytical gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... grade nitrogen as the diluent. (b) Gases for the hydrocarbon analyzer shall be single blends of propane... check gases shall contain propane at a concentration greater than 50 percent of range. The...

  20. 40 CFR 92.112 - Analytical gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... grade nitrogen as the diluent. (b) Gases for the hydrocarbon analyzer shall be single blends of propane... check gases shall contain propane at a concentration greater than 50 percent of range. The...

  1. 40 CFR 92.112 - Analytical gases.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... grade nitrogen as the diluent. (b) Gases for the hydrocarbon analyzer shall be single blends of propane... check gases shall contain propane at a concentration greater than 50 percent of range. The...

  2. Observation of the Efimovian Expansion in Scale Invariant Fermi Gases

    E-print Network

    Deng, Shujin; Diao, Pengpeng; Yu, Qianli; Zhai, Hui; Qi, Ran; Wu, Haibin

    2015-01-01

    Scale invariance emerges and plays an important role in strongly correlated many-body systems such as critical regimes nearby phase transitions and the unitary Fermi gases. Discrete scaling symmetry also manifests itself in quantum few-body systems such as the Efimov effect. Here we report both theoretical predication and experimental observation of a novel type expansion dynamics for scale invariant quantum gases. When the frequency of the harmonic trap holding the gas decreases continuously as the inverse of time $t$, surprisingly, the expansion of cloud size exhibits a sequence of plateaus. Remarkably, the locations of these plateaus obey a discrete geometric scaling law with a controllable scale factor and the entire expansion dynamics is governed by a log-periodic function. This striking expansion of quantum Fermi gases shares similar scaling laws and same mathematical description as the Efimov effect. Our work demonstrates the first expansion dynamics of a quantum many-body system with the temporal disc...

  3. Emissions of greenhouse gases in the United States 1997

    SciTech Connect

    1998-10-01

    This is the sixth annual report on aggregate US national emissions of greenhouse gases. It covers emissions over the period 1990--1996, with preliminary estimates of emissions for 1997. Chapter one summarizes some background information about global climate change and the greenhouse effect. Important recent developments in global climate change activities are discussed, especially the third Conference of the Parties to the Framework Convention on Climate Change, which was held in December of 1997 in Kyoto, Japan. Chapters two through five cover emissions of carbon dioxide, methane, nitrous oxide, halocarbons and related gases, respectively. Chapter six describes potential sequestration and emissions of greenhouse gases as a result of land use changes. Six appendices are included in the report. 96 refs., 38 tabs.

  4. Interactive Photochemistry in Earth System Models to Assess Uncertainty in Ozone and Greenhouse Gases. Final report

    SciTech Connect

    Prather, Michael J.; Hsu, Juno; Nicolau, Alex; Veidenbaum, Alex; Smith, Philip Cameron; Bergmann, Dan

    2014-11-07

    Atmospheric chemistry controls the abundances and hence climate forcing of important greenhouse gases including N2O, CH4, HFCs, CFCs, and O3. Attributing climate change to human activities requires, at a minimum, accurate models of the chemistry and circulation of the atmosphere that relate emissions to abundances. This DOE-funded research provided realistic, yet computationally optimized and affordable, photochemical modules to the Community Earth System Model (CESM) that augment the CESM capability to explore the uncertainty in future stratospheric-tropospheric ozone, stratospheric circulation, and thus the lifetimes of chemically controlled greenhouse gases from climate simulations. To this end, we have successfully implemented Fast-J (radiation algorithm determining key chemical photolysis rates) and Linoz v3.0 (linearized photochemistry for interactive O3, N2O, NOy and CH4) packages in LLNL-CESM and for the first time demonstrated how change in O2 photolysis rate within its uncertainty range can significantly impact on the stratospheric climate and ozone abundances. From the UCI side, this proposal also helped LLNL develop a CAM-Superfast Chemistry model that was implemented for the IPCC AR5 and contributed chemical-climate simulations to CMIP5.

  5. Scavenging of dental anesthetic gases.

    PubMed

    Swenson, R D

    1976-03-01

    Results of recent surveys suggest that there are significant health hazards involved with chronic exposure to waste anesthetic gases. While results of these surveys were significant, they did not prove a cause-effect relationship. Considerable evidence in experimental animals suggests such a relationship; it is reasonable to assume that this applies to the clinical situation. An anesthetic technique that uses a circle-system absorber with a scavenging trap and non-recirculating exhaust duct has been described. This system was combined with use of a closed-cell rubber sponge for an oropharyngeal pack that was impermeable to air or anesthetic gases. In addition, a tight-fitting nasal mask or sealed nasopharyngeal tube was used. Ventilation of room air also was improved. These changes produced a 93.3% reduction in halothane and 91.2% reduction in nitrous oxide in the dental operating room. PMID:1062518

  6. Isotopic Analysis and Evolved Gases

    NASA Technical Reports Server (NTRS)

    Swindle, Timothy D.; Boynton, William V.; Chutjian, Ara; Hoffman, John H.; Jordan, Jim L.; Kargel, Jeffrey S.; McEntire, Richard W.; Nyquist, Larry

    1996-01-01

    Precise measurements of the chemical, elemental, and isotopic composition of planetary surface material and gases, and observed variations in these compositions, can contribute significantly to our knowledge of the source(s), ages, and evolution of solar system materials. The analyses discussed in this paper are mostly made by mass spectrometers or some other type of mass analyzer, and address three broad areas of interest: (1) atmospheric composition - isotopic, elemental, and molecular, (2) gases evolved from solids, and (3) solids. Current isotopic data on nine elements, mostly from in situ analysis, but also from meteorites and telescopic observations are summarized. Potential instruments for isotopic analysis of lunar, Martian, Venusian, Mercury, and Pluto surfaces, along with asteroid, cometary and icy satellites, surfaces are discussed.

  7. Annihilation in Gases and Galaxies

    NASA Technical Reports Server (NTRS)

    Drachman, Richard J. (editor)

    1990-01-01

    This publication contains most of the papers, both invited and contributed, that were presented at the Workshop of Annihilation in Gases and Galaxies. This was the fifth in a biennial series associated with the International Conference on the Physics of Electronic and Atomic Collisions. Subjects covered included the scattering and annihilation of positrons and positronium atoms in various media, including those of astrophysical interest. In addition, the topics of antimatter and dark matter were covered.

  8. Inert gases in Sea of Fertility regolith

    NASA Technical Reports Server (NTRS)

    Vinogradov, A. P.; Zadorozhnyy, I. K.

    1974-01-01

    The content and isotopic composition were studied of inert gases -- He, Ne, Ar, Kr, and Xe -- in samples of lunar regolith returned by the Luna 16 automatic station. The samples were taken from depths of about 12 and 30 cm. The high concentrations of inert gases exceed by several orders their concentrations observed in ordinary stony meteorites. The gases in lunar regolith were a complex mixture of gases of different origins: Solar, cosmogenic, radiogenic, and so on. Solar wind gases predominated, distributed in the thin surficial layer of the regolith grains. The concentrations of these gases in the surficial layer is several cubic centimeters per gram. The isotopic composition of the inert gases of solar origin approaches their composition measured in gas-rich meteorites.

  9. The assessment of the impact of aviation NOx on ozone and other radiative forcing responses - The importance of representing cruise altitudes accurately

    NASA Astrophysics Data System (ADS)

    Skowron, A.; Lee, D. S.; De León, R. R.

    2013-08-01

    Aviation emissions of NOx result in the formation of tropospheric ozone (warming) and destruction of a small amount of methane (cooling), positive and negative radiative forcing effects. In addition, the reduction of methane results in a small long-term reduction in tropospheric ozone (cooling) and, in addition, a long-term reduction in water vapour in the stratosphere (cooling) from reduced oxidation of methane, both negative radiative forcing impacts. Taking all these radiative effects together, aircraft NOx is still thought to result in a positive (warming) radiative effect under constant emissions assumptions. Previously, comparative modelling studies have focussed on the variability between models, using the same emissions database. In this study, we rather quantify the variability and uncertainty arising from different estimations of present-day aircraft NOx emissions. Six different aircraft NOx emissions inventories were used in the global chemical transport model, MOZART v3. The inventories were normalized to give the same global emission of NOx in order to remove one element of uncertainty. Emissions differed in the normalized cases by 23% at cruise altitudes (283-200 hPa, where the bulk of emission occurs, globally). However, the resultant short-term ozone chemical perturbation varied by 15% between the different inventories. Once all the effects that give rise to positive and negative radiative impacts were accounted for, the variability of net radiative forcing impacts was 94%. Using these radiative effects to formulate a net aviation NOx Global Warming Potential (GWP) for a 100-year time horizon resulted in GWPs ranging from 60 to 4, over an order of magnitude. It is concluded that the detailed placement of emissions at chemically sensitive cruise altitudes strongly affects the assessment of the total radiative impact, introducing a hitherto previously unidentified large fraction of the uncertainty of impacts between different modelling assessments. It is recommended that future formulations of aircraft NOx emissions focus efforts on the detailed and accurate placement of emissions at cruise altitudes to reduce the uncertainty in future assessments of aviation NOx impacts.

  10. Physics of intense, high energy radiation effects.

    SciTech Connect

    Hjalmarson, Harold Paul; Hartman, E. Frederick; Magyar, Rudolph J.; Crozier, Paul Stewart

    2011-02-01

    This document summarizes the work done in our three-year LDRD project titled 'Physics of Intense, High Energy Radiation Effects.' This LDRD is focused on electrical effects of ionizing radiation at high dose-rates. One major thrust throughout the project has been the radiation-induced conductivity (RIC) produced by the ionizing radiation. Another important consideration has been the electrical effect of dose-enhanced radiation. This transient effect can produce an electromagnetic pulse (EMP). The unifying theme of the project has been the dielectric function. This quantity contains much of the physics covered in this project. For example, the work on transient electrical effects in radiation-induced conductivity (RIC) has been a key focus for the work on the EMP effects. This physics in contained in the dielectric function, which can also be expressed as a conductivity. The transient defects created during a radiation event are also contained, in principle. The energy loss lead the hot electrons and holes is given by the stopping power of ionizing radiation. This information is given by the inverse dielectric function. Finally, the short time atomistic phenomena caused by ionizing radiation can also be considered to be contained within the dielectric function. During the LDRD, meetings about the work were held every week. These discussions involved theorists, experimentalists and engineers. These discussions branched out into the work done in other projects. For example, the work on EMP effects had influence on another project focused on such phenomena in gases. Furthermore, the physics of radiation detectors and radiation dosimeters was often discussed, and these discussions had impact on related projects. Some LDRD-related documents are now stored on a sharepoint site (https://sharepoint.sandia.gov/sites/LDRD-REMS/default.aspx). In the remainder of this document the work is described in catergories but there is much overlap between the atomistic calculations, the continuum calculations and the experiments.

  11. Probing the effect of Gases on Activated Lunar Simulant

    NASA Astrophysics Data System (ADS)

    Salama, F.; Ricketts, C. L.; Sciamma-O'Brien, Ella; Contreras, C. S.; Mattioda, A. L.; Yates, E. L.; Iraci, L. T.; Ricca, A.

    2012-05-01

    The lunar surface is constantly ‘activated’ through bombardment of solar radiation and micrometeorites. This ‘activation’ is significant enough to affect the surface dust by creating free radicals, dangling bonds and lattice defeats. Hence, the reactive effect of the dust particles on spacecraft instrumentation and human toxicology is a concern. There is currently little information on the surface chemical activation of lunar regolith after exposure to gases brought to the Moon by human activities. Information is needed in order to understand the regolith toxicity, effect on spacecraft, determine lunar dust exposure limits and meet the needs of the technological development of appropriate physical/chemical tools for regolith passivation. In this experimental study, we grind JSC-1af lunar simulant to simulate micrometeorite impacts and expose the simulant to vacuum ultraviolet (VUV) light to simulate solar radiation. We then flow a variety of gases (N2, CO2, CH4) over the simulant to simulate the exposure of the activated dust to gases humans would bring to the Moon. Mass spectra are taken using the Reflectron Time-Of-Flight Mass Spectrometer at NASA Ames’ Cosmic Simulation facility (COSmIC), before, during and after exposure to VUV and the various gases. Infrared spectra and Scanning Electron Microscope images of the simulant are taken, before and after activation and gas exposure. Future plans include theory and replicating these experiments using real lunar dust. Here we describe our new custom built lunar dust holder, experimental procedure and latest results. Acknowledgments: NASA LASER supports this research. E.S.O. and C.S.C. acknowledge the support of the NASA Postdoctoral Program.

  12. Climate Change and Greenhouse Gases

    NASA Technical Reports Server (NTRS)

    Ledley, Tamara S.; Sundquist, Eric; Schwartz, Stephen; Hall, Dorothy K.; Fellows, Jack; Killeen, Timothy

    1999-01-01

    The American Geophysical Union (AGU), as a scientific organization devoted to research on the Earth and space sciences, provides current scientific information to the public on issues pertinent to geophysics. The Council of the AGU approved a position statement on Climate Change and Greenhouse Gases in December 1998. The statement, together with a short summary of the procedures that were followed in its preparation, review, and adoption were published in the February 2, 1999 issue of Eos ([AGU, 1999]. The present article reviews scientific understanding of this issue as presented in peer-reviewed publications that serves as the underlying basis of the position statement.

  13. Pharmacologic inhibition of ATR and ATM offers clinically important distinctions to enhancing platinum or radiation response in ovarian, endometrial, and cervical cancer cells

    PubMed Central

    Teng, Pang-ning; Bateman, Nicholas W.; Darcy, Kathleen M.; Hamilton, Chad A.; Maxwell, George Larry; Bakkenist, Christopher J.; Conrads, Thomas P.

    2015-01-01

    Objective Significant reductions in gynecologic (GYN) cancer mortality and morbidity require treatments that prevent and reverse resistance to chemotherapy and radiation. The objective of this study was to determine if pharmacologic inhibition of key DNA damage response kinases in GYN cancers would enhance cell killing by platinum-based chemotherapy and radiation. Methods A panel of human ovarian, endometrial and cervical cancer cell lines were treated with platinum drugs or ionizing radiation (IR) along with small molecule pharmacological kinase inhibitors of Ataxia telangiectasia mutated (ATM) and ATM and Rad-3-related (ATR). Results Pharmacologic inhibition of ATR significantly enhanced platinum drug response in all GYN cancer cell lines tested, whereas inhibition of ATM did not enhance the response to platinum drugs. Co-inhibition of ATM and ATR did not enhance platinum kill beyond that observed by inhibition of ATR alone. By contrast, inhibiting either ATR or ATM enhanced the response to IR in all GYN cancer cells, with further enhancement achieved with co-inhibition. Conclusions These studies highlight actionable mechanisms operative in GYN cancer cells with potential to maximize response of platinum agents and radiation in newly diagnosed as well as recurrent gynecologic cancers. PMID:25560806

  14. Solar radiation resource assessment

    SciTech Connect

    Not Available

    1990-11-01

    The bulletin discusses the following: introduction; Why is solar radiation resource assessment important Understanding the basics; the solar radiation resource assessment project; and future activities.

  15. Radiation technology for environmental conservation

    NASA Astrophysics Data System (ADS)

    Machi, S.

    The use of radiation technology for environmental conservation is becoming increasingly important. Commercial plants for the radiation treatment of sewage sludge to reduce pathogenic micro-organisms have been operating in the Federal Republic of Germany for the past ten years and their technical and economical feasibility has been demonstrated. Irradiation of dried sludge has been developed at the Sandia National Laboratory (USA) using Cs-137, and the construction of a commercial plant is planned in Albuquerque. At the Japan Atomic Energy Research Institute (JAERI), efforts are under way to increase the rate of composting of sludge by radiation. Regarding waste water treatment, a significant synergistic effect of radiation and ozone was found in the reduction of TOC. The construction of a gamma irradiation plant is in the planning stage in Canada, for the disinfection of virus-contaminated waste effluents from the Canadian Animal Disease Research Institute. The treatment of exhaust gases by electron beam has been studied in Japan using a large pilot plant which demonstrated that 90% of SO 2 and 80% of NO x can be removed from the flue gas of iron ore sintering furnaces. The US Department of Energy is assisting in projects for the further development of this technology for combined removal of SO 2 and NO x in flue gas from coal burning power stations.

  16. Predicting Flows of Rarefied Gases

    NASA Technical Reports Server (NTRS)

    LeBeau, Gerald J.; Wilmoth, Richard G.

    2005-01-01

    DSMC Analysis Code (DAC) is a flexible, highly automated, easy-to-use computer program for predicting flows of rarefied gases -- especially flows of upper-atmospheric, propulsion, and vented gases impinging on spacecraft surfaces. DAC implements the direct simulation Monte Carlo (DSMC) method, which is widely recognized as standard for simulating flows at densities so low that the continuum-based equations of computational fluid dynamics are invalid. DAC enables users to model complex surface shapes and boundary conditions quickly and easily. The discretization of a flow field into computational grids is automated, thereby relieving the user of a traditionally time-consuming task while ensuring (1) appropriate refinement of grids throughout the computational domain, (2) determination of optimal settings for temporal discretization and other simulation parameters, and (3) satisfaction of the fundamental constraints of the method. In so doing, DAC ensures an accurate and efficient simulation. In addition, DAC can utilize parallel processing to reduce computation time. The domain decomposition needed for parallel processing is completely automated, and the software employs a dynamic load-balancing mechanism to ensure optimal parallel efficiency throughout the simulation.

  17. Long-term outcomes in breast cancer patients with ten or more positive axillary nodes treated with combined-modality therapy: The importance of radiation field selection

    SciTech Connect

    Chang, Daniel T.; Feigenberg, Steven J.; Indelicato, Daniel J.; Morris, Christopher G.; Lightsey, Judith; Grobmyer, Stephen R.; Copeland, Edward M.; Mendenhall, Nancy P. . E-mail: mendenan@shands.ufl.edu

    2007-03-15

    Purpose: To determine the long-term outcome of a consistent treatment approach with electron beam postmastectomy radiation therapy (PMRT) in breast cancer patients with {>=}10 positive nodes treated with combined-modality therapy. Methods and Materials: TSixty-three breast cancer patients with {>=}10 positive lymph nodes were treated with combined-modality therapy using an electron beam en face technique for PMRT at University of Florida. Patterns of recurrence were studied for correlation with radiation fields. Potential clinical and treatment variables were tested for possible association with local-regional control (LRC), disease-free survival (DFS), and overall survival (OS). Results: TAt 5, 10, and 15 years, OS rates were 57%, 36%, and 27%, respectively; DFS rates were 46%, 37%, and 34%; and LRC rates were 87%, 87%, and 87%. No clinical or treatment variables were associated with OS or DFS. The use of supplemental axillary radiation (SART) (p = 0.012) and pathologic N stage (p = 0.053) were associated with improved LRC. Patients who received SART had a higher rate of LRC than those who did not. Moderate to severe arm edema developed in 17% of patients receiving SART compared with 7% in patients not treated with SART (p = 0.28). Conclusions: TA substantial percentage of patients with {>=}10 positive lymph nodes survive breast cancer. The 10-year overall survival in these patients was 36%. The addition of SART was associated with better LRC.

  18. EOSN: A TOUGH2 module for noble gases

    SciTech Connect

    Shan, Chao; Pruess, Karsten

    2003-03-07

    We developed a new fluid property module for TOUGH2, called EOSN, to simulate transport of noble gases in the subsurface. Currently, users may select any of five different noble gases as well as CO2, two at a time. For the three gas components (air and two user-specified noble gases) in EOSN, the Henry's coefficients and the diffusivities in the gas phase are no longer assumed constants, but are temperature dependent. We used the Crovetto et al. (1982) model to estimate Henry's coefficients, and the Reid et al. (1987) correlations to calculate gas phase diffusivities. The new module requires users to provide names of the selected noble gases, which properties are provided internally. There are options for users to specify any (non-zero) molecular weights and half-lives for the gas components. We provide two examples to show applications of TOUGH2IEOSN. While temperature effects are relatively insignificant for one example problem where advection is dominant, they cause almost an order of magnitude difference for the other case where diffusion becomes a dominant process and temperature variations are relatively large. It appears that thermodynamic effects on gas diffusivities and Henry's coefficients can be important for low-permeability porous media and zones with large temperature variations.

  19. BOOK REVIEW: Kinetic Theory of Granular Gases

    NASA Astrophysics Data System (ADS)

    Trizac, Emmanuel

    2005-11-01

    Granular gases are composed of macroscopic bodies kept in motion by an external energy source such as a violent shaking. The behaviour of such systems is quantitatively different from that of ordinary molecular gases: due to the size of the constituents, external fields have a stronger effect on the dynamics and, more importantly, the kinetic energy of the gas is no longer a conserved quantity. The key role of the inelasticity of collisions has been correctly appreciated for about fifteen years, and the ensuing consequences in terms of phase behaviour or transport properties studied in an increasing and now vast body of literature. The purpose of this book is to help the newcomer to the field in acquiring the essential theoretical tools together with some numerical techniques. As emphasized by the authors—who were among the pioneers in the domain— the content could be covered in a one semester course for advanced undergraduates, or it could be incorporated in a more general course dealing with the statistical mechanics of dissipative systems. The book is self-contained, clear, and avoids mathematical complications. In order to elucidate the main physical ideas, heuristic points of views are sometimes preferred to a more rigorous route that would lead to a longer discussion. The 28 chapters are short; they offer exercises and worked examples, solved at the end of the book. Each part is supplemented with a relevant foreword and a useful summary including take-home messages. The editorial work is of good quality, with very few typographical errors. In spite of the title, kinetic theory stricto sensu is not the crux of the matter covered. The authors discuss the consequences of the molecular chaos assumption both at the individual particle level and in terms of collective behaviour. The first part of the book addresses the mechanics of grain collisions. It is emphasized that considering the coefficient of restitution ? —a central quantity governing the inelasticity of inter-grain encounters—as velocity independent is inconsistent with the mechanical point of view. An asymptotic expression for the impact velocity dependence of ? is therefore derived for visco-elastic spheres. The important inelastic Boltzmann equation is introduced in part II and the associated velocity distribution characterized for a force-free medium (so-called free cooling regime). Transport processes can then be analyzed in part III at the single particle level, and part IV from a more macroscopic viewpoint. The corresponding Chapman Enskog-like hydrodynamic approach is worked out in detail, in a clear fashion. Finally, the tendency of granular gases to develop instabilities is illustrated in part V where the hydrodynamic picture plays a pivotal role. This book clearly sets the stage. For the sake of simplicity, the authors have discarded some subtle points, such as the open questions underlying the hydrodynamic description (why include the temperature among the hydrodynamic modes, and what about the separation of space and time scales between kinetic and hydrodynamic excitations?). Such omissions are understandable. To a certain extent however, the scope of the book is centered on previous work by the authors, and I have a few regrets. Special emphasis is put on the (variable ?) visco-elastic model, which enhances the technical difficulty of the presentation. On the other hand, the important physical effects including scaling laws, hydrodynamic behaviour and structure formation, can be understood in two steps, from the results derived within the much simpler constant ? model, allowing subsequently \\varepsilon to depend on the granular temperature. The authors justify their choice with the inconsistency of the constant ? route. The improvements brought by the visco-elastic model remain to be assessed, since the rotational degrees of freedom, discarded in the book, play an important role and require due consideration of both tangential and normal restitution coefficients, that are again velocity dependent. This seems to be the price of a cons

  20. Cooling Atomic Gases With Disorder.

    PubMed

    Paiva, Thereza; Khatami, Ehsan; Yang, Shuxiang; Rousseau, Valéry; Jarrell, Mark; Moreno, Juana; Hulet, Randall G; Scalettar, Richard T

    2015-12-11

    Cold atomic gases have proven capable of emulating a number of fundamental condensed matter phenomena including Bose-Einstein condensation, the Mott transition, Fulde-Ferrell-Larkin-Ovchinnikov pairing, and the quantum Hall effect. Cooling to a low enough temperature to explore magnetism and exotic superconductivity in lattices of fermionic atoms remains a challenge. We propose a method to produce a low temperature gas by preparing it in a disordered potential and following a constant entropy trajectory to deliver the gas into a nondisordered state which exhibits these incompletely understood phases. We show, using quantum Monte Carlo simulations, that we can approach the Néel temperature of the three-dimensional Hubbard model for experimentally achievable parameters. Recent experimental estimates suggest the randomness required lies in a regime where atom transport and equilibration are still robust. PMID:26705614

  1. Fluorescence Imaging of Quantum Gases

    NASA Astrophysics Data System (ADS)

    Weitenberg, Christof

    2015-09-01

    Quantum gases in optical lattices have proven a prolific platform to study condensed matter models such as the Bose-Hubbard model. The recently achieved in situ fluorescence imaging of low-dimensional systems has pushed the detection capabilities to a fully microscopic level. The method yields single-site and single-atom resolved images of the lattice gas in a single experimental run, thus giving direct access to fluctuations and correlation functions in the many-body system. These quantum gas microscopes have been used to study the superfluid-Mott insulator quantum phase transition at the single-atom level. Moreover, singlesite resolved addressing allows flipping the spin of individual atoms in a Mott insulator, thus deterministically creating local spin excitations whose dynamics can be observed. In this chapter, we will describe the implementation of the technique and discuss some of the obtained results.

  2. Continuous Processing with Mars Gases

    NASA Astrophysics Data System (ADS)

    Parrish, Clyde; Jennings, Paul

    2001-01-01

    Current Martian missions call for the production of oxygen for breathing, and fuel and oxygen for propulsion to be produced from atmospheric carbon dioxide (CO2). Adsorption and freezing are the two methods considered for capturing CO, from the atmosphere. However, the nitrogen (N2) and argon (Ar), which make up less than 5 percent of the atmosphere, cause difficulties with both of these processes by blocking the CO2, This results in the capture process rapidly changing from a pressure driven process to a diffusion controlled process. To increase the CO, capture rates, some type of mechanical pump is usually proposed to remove the N2 and Ar. The N2 and Ar are useful and have been proposed for blanketing and pressurizing fuel tanks and as buffer gas for breathing air for manned missions. Separation of the Martian gases with the required purity can be accomplished with a combination of membranes. These membrane systems do not require a high feed pressure and provide suitable separation. Therefore, by use of the appropriate membrane combination with the Martian atmosphere supplied by a compressor a continuous supply of CO2 for fuel and oxygen production can be supplied. This phase of our program has focused on the selection of the membrane system. Since permeation data for membranes did not exist for Martian atmospheric pressures and temperatures, this information had to be compiled. The general trend as the temperature was lowered was for the membranes to become more selective. In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar. This paper will present the membrane data, provide the design requirements for a compressor, and compare the results with adsorption and freezer methods.

  3. Continuous Processing With Mars Gases

    NASA Astrophysics Data System (ADS)

    Parrish, Clyde; Jennings, Paul

    2000-01-01

    Current Martian missions call for the production of oxygen for breathing, and fuel and oxygen for propulsion to be produced from atmospheric carbon dioxide (CO2). Adsorption and freezing are the two methods considered for capturing CO2 from the atmosphere. However, the nitrogen (N2) and argon (Ar), which make up less than 5 percent of the atmosphere, cause difficulties with both of these processes by blocking the CO2. This results in the capture process rapidly changing from a pressure driven process to a diffusion controlled process. To increase the CO2 capture rates, some type of mechanical pump is usually proposed to remove the N2 and Ar. The N2 and Ar are useful and have been proposed for blanketing and pressurizing fuel tanks and as buffer gas for breathing air for manned missions. Separation of the Martian gases with the required purity can be accomplished with a combination of membranes. These membrane systems do not require a high feed pressure and provide suitable separation. Therefore, by use of the appropriate membrane combination with the Martian atmosphere supplied by a compressor a continuous Supply Of CO2 for fuel and oxygen production can be supplied. This phase of our program has focused on the selection of the membrane system. Since permeation data for membranes did not exist for Martian atmospheric pressures and temperatures, this information had to be compiled. The general trend as the temperature was lowered was for the membranes to become more selective. In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar. This paper will present the membrane data, provide the design requirements for a compressor, and compare the results with adsorption and freezer methods.

  4. Method of concurrently filtering particles and collecting gases

    DOEpatents

    Mitchell, Mark A; Meike, Annemarie; Anderson, Brian L

    2015-04-28

    A system for concurrently filtering particles and collecting gases. Materials are be added (e.g., via coating the ceramic substrate, use of loose powder(s), or other means) to a HEPA filter (ceramic, metal, or otherwise) to collect gases (e.g., radioactive gases such as iodine). The gases could be radioactive, hazardous, or valuable gases.

  5. 40 CFR 86.1514 - Analytical gases.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... carbon monoxide on a dry basis. (b) If the raw CO sampling system specified in 40 CFR part 1065 is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used. (c) If a CVS sampling system is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used....

  6. 40 CFR 86.1514 - Analytical gases.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... on a dry basis. (b) If the raw CO sampling system specified in 40 CFR part 1065 is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used. (c) If a CVS sampling system is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used....

  7. 40 CFR 86.1514 - Analytical gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... carbon monoxide on a dry basis. (b) If the raw CO sampling system specified in 40 CFR part 1065 is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used. (c) If a CVS sampling system is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used....

  8. 40 CFR 86.1514 - Analytical gases.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... carbon monoxide on a dry basis. (b) If the raw CO sampling system specified in 40 CFR part 1065 is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used. (c) If a CVS sampling system is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used....

  9. 40 CFR 86.1514 - Analytical gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... carbon monoxide on a dry basis. (b) If the raw CO sampling system specified in 40 CFR part 1065 is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used. (c) If a CVS sampling system is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used....

  10. Thermalization of Gases: A First Principles Approach

    E-print Network

    Clifford Chafin

    2015-06-20

    Previous approaches of emergent thermalization for condensed matter based on typical wavefunctions are extended to generate an intrinsically quantum theory of gases. Gases are fundamentally quantum objects at all temperatures, by virtue of rapid delocalization of their constituents. When there is a sufficiently broad spread in the energy of eigenstates, a well-defined temperature is shown to arise by photon production when the samples are optically thick. This produces a highly accurate approximation to the Planck distribution so that thermalization arises from the initial data as a consequence of purely quantum and unitary dynamics. These results are used as a foil for some common hydrodynamic theory of ultracold gases. It is suggested here that strong history dependence typically remains in these gases and so limits the validity of thermodynamics in their description. These problems are even more profound in the extension of hydrodynamics to such gases when they are optically thin, even when their internal energy is not low. We investigate rotation of elliptically trapped gases and consistency problems with deriving a local hydrodynamic approach. The presence of vorticity that is "hidden" from order parameter approaches is discussed along with some buoyancy intrinsically associated with vorticity that gives essential quantum corrections to gases in the regimes where standard perturbation approaches to the Boltzmann equations are known to fail to converge. These results suggest that studying of trapped gases in the far from ultracold regions may yield interesting results not described by classical hydrodynamics.

  11. Noble gases and the early history of the Earth: Inappropriate paradigms and assumptions inhibit research and communication

    NASA Technical Reports Server (NTRS)

    Huss, G. R.; Alexander, E. C., Jr.

    1985-01-01

    The development of models as tracers of nobel gases through the Earth's evolution is discussed. A new set of paradigms embodying present knowledge was developed. Several important areas for future research are: (1) measurement of the elemental and isotopic compositions of the five noble gases in a large number of terrestrial materials, thus better defining the composition and distribution of terrestrial noble gases; (2) determinations of relative diffusive behavior, chemical behavior, and the distribution between solid and melt of noble gases under mantle conditions are urgently needed; (3) disequilibrium behavior in the nebula needs investigation, and the behavior of plasmas and possible cryotrapping on cold nebular solids are considered.

  12. Design of a multifunctional and portable detector for indoor gases

    NASA Astrophysics Data System (ADS)

    Zhang, Liping; Wang, Yutian; Li, Taishan

    2003-09-01

    With the increase of the living standards of city dwellers, home decoration has been more and more popular these years. Different kinds of material have come into people's home, which brings about beauties to the house as well as some bad effect. Because of differences in manufacturing techniques and quality, much of the material will emit poisonous gases more or less. Even if you have selected the qualified product, the toal amount of gases in you houses may not be guaranteed because of the simple reason that more than one kind of material are applied. Living in the complex environment for a long time will eventually have a bad effect on one's health. In addition the fear of the harm to be done will exert great impact psychologically. In another aspect, the coal-gas in the house-hood for cooking is also explosive and poisonous. In conclusion, the research on the indoor hazardous gases measurement and alarm device is of much economic and practical importance. The device is portable and versatile. We use rechargeable battery as the power supply. The device can detect the density of gases at the ppb level for the emission of the material and the measured value can be shown on the display. As for coal gas it can detect the percentage of LEL and make sound of alarm. We use two kinds of gas-sensors in the device, with catalytic combustion principal for coal gas detection and the PID method for the gas emissions of the decoration material. UV will destroy harmful material (such as: ammonia, dimethylamine, methyl-sulfhydrate, benzene etc.) into positive or negative ions. The sensor detects the electric charges of ionized gases and converts them into electric current signals. It is then amplified and changed into digits by amplifier and A/D. The digit signal is processed by micro-controller system of the device.

  13. Impact degassing of water and noble gases from silicates

    NASA Technical Reports Server (NTRS)

    Azuma, S.; Hiyagon, H.; Iijima, Y.; Syono, Y.

    1994-01-01

    Previous shock experiments by Ahrens and his colleagues show that degassing of H2O and CO2 occurs at 8-65GPa from hydrous minerals such as serpentine. In early solar system, the impact degassing would have played an important part in the formation of primary-atmospheres of the terrestrial planets. However, degassing conditions of noble gases are not well-known because there are few experiments for them. We conducted some shock recovery experiments to investigate the degassing condition and to understand the degassing mechanisms of water and noble gases. We used natural richterites (Ri), amphibolites (Am), serpentines (Sep) and orthoclases (or) as target samples. These, except Sep, contain radiogenic noble gases such as (40)Ar. The samples were put in stainless steel containers, and were show by a rail gun at ISAS or single-stage powder guns at Nagoya or Tohoku University, Japan. We used two kinds of containers: 'open' type containers having a ventilating path for released volatiles for most of samples and 'closed' type ones for some samples for comparison. On Ri and Sep, we made shock experiments for pre-heated (at 400-500 C) and unheated targets, and for powdered and uncrushed samples. Water and noble gases were analyzed both for the recovered shocked samples and the unshocked original samples, and the fractions of the degassed volatiles were calculated by comparing them. Water content in the sample was analyzed by thermo-gravimetry. Noble gases were extracted by heating the samples under high vacuum and analyzed with a sector-type mass spectrometer.

  14. Comparison of natural gases accumulated in Oligocene strata with hydrous pyrolysis gases from Menilite Shales of the Polish Outer Carpathians

    USGS Publications Warehouse

    Kotarba, M.J.; Curtis, John B.; Lewan, M.D.

    2009-01-01

    This study examined the molecular and isotopic compositions of gases generated from different kerogen types (i.e., Types I/II, II, IIS and III) in Menilite Shales by sequential hydrous pyrolysis experiments. The experiments were designed to simulate gas generation from source rocks at pre-oil-cracking thermal maturities. Initially, rock samples were heated in the presence of liquid water at 330 ??C for 72 h to simulate early gas generation dominated by the overall reaction of kerogen decomposition to bitumen. Generated gas and oil were quantitatively collected at the completion of the experiments and the reactor with its rock and water was resealed and heated at 355 ??C for 72 h. This condition simulates late petroleum generation in which the dominant overall reaction is bitumen decomposition to oil. This final heating equates to a cumulative thermal maturity of 1.6% Rr, which represents pre-oil-cracking conditions. In addition to the generated gases from these two experiments being characterized individually, they are also summed to characterize a cumulative gas product. These results are compared with natural gases produced from sandstone reservoirs within or directly overlying the Menilite Shales. The experimentally generated gases show no molecular compositions that are distinct for the different kerogen types, but on a total organic carbon (TOC) basis, oil prone kerogens (i.e., Types I/II, II and IIS) generate more hydrocarbon gas than gas prone Type III kerogen. Although the proportionality of methane to ethane in the experimental gases is lower than that observed in the natural gases, the proportionality of ethane to propane and i-butane to n-butane are similar to those observed for the natural gases. ??13C values of the experimentally generated methane, ethane and propane show distinctions among the kerogen types. This distinction is related to the ??13C of the original kerogen, with 13C enriched kerogen generating more 13C enriched hydrocarbon gases than kerogen less enriched in 13C. The typically assumed linear trend for ??13C of methane, ethane and propane versus their reciprocal carbon number for a single sourced natural gas is not observed in the experimental gases. Instead, the so-called "dogleg" trend, exemplified by relatively 13C depleted methane and enriched propane as compared to ethane, is observed for all the kerogen types and at both experimental conditions. Three of the natural gases from the same thrust unit had similar "dogleg" trends indicative of Menilite source rocks with Type III kerogen. These natural gases also contained varying amounts of a microbial gas component that was approximated using the ????13C for methane and propane determined from the experiments. These approximations gave microbial methane components that ranged from 13-84%. The high input of microbial gas was reflected in the higher gas:oil ratios for Outer Carpathian production (115-1568 Nm3/t) compared with those determined from the experiments (65-302 Nm3/t). Two natural gas samples in the far western part of the study area had more linear trends that suggest a different organic facies of the Menilite Shales or a completely different source. This situation emphasizes the importance of conducting hydrous pyrolysis on samples representing the complete stratigraphic and lateral extent of potential source rocks in determining specific genetic gas correlations. ?? 2009 Elsevier Ltd.

  15. Sun and dust versus greenhouse gases - An assessment of their relative roles in global climate change

    NASA Technical Reports Server (NTRS)

    Hansen, James E.; Lacis, Andrew A.

    1990-01-01

    Many mechanisms, including variations in solar radiation and atmospheric aerosol concentrations, compete with anthropogenic greenhouse gases as causes of global climate change. Comparisons of available data show that solar variability will not counteract greenhouse warming and that future observations will need to be made to quantify the role of tropospheric aerosols, for example.

  16. Classical disordered ground states: Super-ideal gases and stealth and equi-luminous materials

    E-print Network

    Stillinger, Frank

    " materials, which are transparent to incident radiation at certain wavelengths; ii "super-ideal" gases, which procedure. In a recent example of a "forward" problem, the scattering from glass ceramics with nanometer-known disordered many-body configuration.7 These ceramics are of interest in photonics applications because

  17. Research of medical gases in Poland

    PubMed Central

    2013-01-01

    Research of medical gases is well established in Poland and has been marked with the foundation of several professional societies. Numerous academic centers including those dealing with hyperbaric and diving medicine conduct studies of medical gases, in vast majority supported with intramural funds. In general, Polish research of medical gases is very much clinical in nature, covering new applications and safety of medical gases in medicine; on the other hand there are several academic centers pursuing preclinical studies, and elaborating basic theories of gas physiology and mathematical modeling of gas exchange. What dominates is research dealing with oxygen and ozone as well as studies of anesthetic gases and their applications. Finally, several research directions involving noble gas, hydrogen and hydrogen sulfide for cell protection, only begin to gain recognition of basic scientists and clinicians. However, further developments require more monetary spending on research and clinical testing as well as formation of new collective bodies for coordinating efforts in this matter. PMID:23916016

  18. Thermalization of Gases: A First Principles Approach

    E-print Network

    Chafin, Clifford

    2015-01-01

    Previous approaches of emergent thermalization for condensed matter based on typical wavefunctions are extended to generate an intrinsically quantum theory of gases. Gases are fundamentally quantum objects at all temperatures, by virtue of rapid delocalization of their constituents. When there is a sufficiently broad spread in the energy of eigenstates, a well-defined temperature is shown to arise by photon production when the samples are optically thick. This produces a highly accurate approximation to the Planck distribution so that thermalization arises from the initial data as a consequence of purely quantum and unitary dynamics. These results are used as a foil for some common hydrodynamic theory of ultracold gases. It is suggested here that strong history dependence typically remains in these gases and so limits the validity of thermodynamics in their description. These problems are even more profound in the extension of hydrodynamics to such gases when they are optically thin, even when their internal ...

  19. Isotopic composition of gases from mud volcanoes

    SciTech Connect

    Valysaev, B.M.; Erokhin, V.E.; Grinchenko, Y.I.; Prokhorov, V.S.; Titkov, G.A.

    1985-09-01

    A study has been made of the isotopic composition of the carbon in methane and carbon dioxide, as well as hydrogen in the methane, in the gases of mud volcanoes, for all main mud volcano areas in the USSR. The isotopic composition of carbon and hydrogen in methane shows that the gases resemble those of oil and gas deposits, while carbon dioxide of these volcanoes has a heavier isotopic composition with a greater presence of ''ultraheavy'' carbon dioxide. By the chemical and isotopic composition of gases, Azerbaidzhan and South Sakhalin types of mud volcano gases have been identified, as well as Bulganak subtypes and Akhtala and Kobystan varieties. Correlations are seen between the isotopic composition of gases and the geological build of mud volcano areas.

  20. Greenhouse gases in the stratosphere

    SciTech Connect

    Wenyi Zhong; Haigh, J.D. ); Pyle, J.A. )

    1993-02-20

    The potential radiative forcing in the stratosphere of changing concentrations of ozone, methane, nitrous oxide and chlorofluorocarbons 11 and 12 is assessed. Significant changes in heating rate in the lower stratosphere are found. The response of a fully interactive radiative-photochemical-dynamical two-dimensional model to such changes in gaseous concentrations is investigated. The inclusion of CH[sub 4], N[sub 2]O and the CFC in the radiation scheme causes a small (1 K) decrease in temperature throughout the stratosphere after 50 model years with a resulting increase in ozone column up to 1% in summer high latitudes. An experiment in which lower stratospheric ozone concentrations were forcibly reduced in line with recent satellite observations results in significant (several degrees) temperature decrease in this region. Such decreases may be very significant in maintaining polar ozone loss. 20 refs., 12 figs., 2 tabs.

  1. Impact of Radiatively Active Water Ice Clouds in the GEM-Mars GCM

    NASA Astrophysics Data System (ADS)

    Neary, L.; Daerden, F.

    2015-10-01

    Water ice clouds have proven to be an important driver in the temperature distribution and overall climate of the Martian atmosphere. Clouds have both a direct and indirect radiative effect on temperature and circulation, which in turn can modify the water vapour distribution and that of other trace gases.We have included the radiative effect of water ice clouds (RAC) in the GEM-Mars GCM model, using Mie code and optical indices to compute the scattering properties of ice particles.We present preliminary results from simulations with and without RAC, and compare these initial tests with Mars Climate Sounder (MCS), Thermal Emission Spectrometer (TES) and Mars Color Imager (MARCI).

  2. Green house gases Ozone depletion

    E-print Network

    Zevenhoven, Ron

    · = expressed in terms of radiative forcing, which is used to compare how a range of human and natural factors enhancement of biological sinks · Biomass · Ocean · Atmosphere · Sediment · CO2 capture and storage · pre Capture Source IPCC, 2005 #12;MZ 16/36 Post combustion CO2 capture Disadvantages -High energy penalty

  3. Measurement of individual doses of radiation by personal dosimeter is important for the return of residents from evacuation order areas after nuclear disaster.

    PubMed

    Orita, Makiko; Hayashida, Naomi; Taira, Yasuyuki; Fukushima, Yoshiko; Ide, Juichi; Endo, Yuuko; Kudo, Takashi; Yamashita, Shunichi; Takamura, Noboru

    2015-01-01

    To confirm the availability of individual dose evaluation for the return of residents after the accident at the Fukushima Dai-ichi Nuclear Power Plant (FNPP), we evaluated individual doses of radiation as measured by personal dosimeters in residents who temporarily stayed in Evacuation Order Areas in Kawauchi village, which is partially located within a 20 km radius of the FNPP. We also compared individual doses with the external radiation doses estimated from the ambient dose rates and with doses estimated from the concentrations of radionuclides in the soil around each individual's house. Individual doses were significantly correlated with the ambient doses in front of the entrances to the houses (r = 0.90, p<0.01), in the backyards (r = 0.41, p<0.01) and in the nearby fields (r = 0.80, p<0.01). The maximum cumulative ambient doses in the backyards and fields around the houses were 6.38 and 9.27 mSv/y, respectively. The maximum cumulative individual dose was 3.28 mSv/y, and the median and minimum doses were 1.35 and 0.71 mSv/y. The estimated external effective doses from concentrations of artificial radionuclides in soil samples ranged from 0.03 to 23.42 mSv/y. The individual doses were moderately correlated with external effective doses in the backyards (r = 0.38, p<0.01) and in the fields (r = 0.36, p<0.01); however, the individual doses were not significantly correlated with the external effective doses in front of the entrances (r = 0.01, p = 0.92). Our study confirmed that individual doses are low levels even in the evacuation order area in Kawauchi village, and external effective dose levels are certainly decreasing due to the decay of artificial radionuclides and the decontamination of contaminated soil. Long-term follow-up of individual doses as well as internal-exposure doses, environmental monitoring and reconstruction of infrastructure are needed so that residents may return to their hometowns after a nuclear disaster. PMID:25806523

  4. Measurement of Individual Doses of Radiation by Personal Dosimeter Is Important for the Return of Residents from Evacuation Order Areas after Nuclear Disaster

    PubMed Central

    Orita, Makiko; Hayashida, Naomi; Taira, Yasuyuki; Fukushima, Yoshiko; Ide, Juichi; Endo, Yuuko; Kudo, Takashi; Yamashita, Shunichi; Takamura, Noboru

    2015-01-01

    To confirm the availability of individual dose evaluation for the return of residents after the accident at the Fukushima Dai-ichi Nuclear Power Plant (FNPP), we evaluated individual doses of radiation as measured by personal dosimeters in residents who temporarily stayed in Evacuation Order Areas in Kawauchi village, which is partially located within a 20 km radius of the FNPP. We also compared individual doses with the external radiation doses estimated from the ambient dose rates and with doses estimated from the concentrations of radionuclides in the soil around each individual’s house. Individual doses were significantly correlated with the ambient doses in front of the entrances to the houses (r = 0.90, p<0.01), in the backyards (r = 0.41, p<0.01) and in the nearby fields (r = 0.80, p<0.01). The maximum cumulative ambient doses in the backyards and fields around the houses were 6.38 and 9.27 mSv/y, respectively. The maximum cumulative individual dose was 3.28 mSv/y, and the median and minimum doses were 1.35 and 0.71 mSv/y. The estimated external effective doses from concentrations of artificial radionuclides in soil samples ranged from 0.03 to 23.42 mSv/y. The individual doses were moderately correlated with external effective doses in the backyards (r = 0.38, p<0.01) and in the fields (r = 0.36, p<0.01); however, the individual doses were not significantly correlated with the external effective doses in front of the entrances (r = 0.01, p = 0.92). Our study confirmed that individual doses are low levels even in the evacuation order area in Kawauchi village, and external effective dose levels are certainly decreasing due to the decay of artificial radionuclides and the decontamination of contaminated soil. Long-term follow-up of individual doses as well as internal-exposure doses, environmental monitoring and reconstruction of infrastructure are needed so that residents may return to their hometowns after a nuclear disaster. PMID:25806523

  5. Driven fragmentation of granular gases.

    PubMed

    Cruz Hidalgo, Raúl; Pagonabarraga, Ignacio

    2008-06-01

    The dynamics of homogeneously heated granular gases which fragment due to particle collisions is analyzed. We introduce a kinetic model which accounts for correlations induced at the grain collisions and analyze both the kinetics and relevant distribution functions these systems develop. The work combines analytical and numerical studies based on direct simulation Monte Carlo calculations. A broad family of fragmentation probabilities is considered, and its implications for the system kinetics are discussed. We show that generically these driven materials evolve asymptotically into a dynamical scaling regime. If the fragmentation probability tends to a constant, the grain number diverges at a finite time, leading to a shattering singularity. If the fragmentation probability vanishes, then the number of grains grows monotonously as a power law. We consider different homogeneous thermostats and show that the kinetics of these systems depends weakly on both the grain inelasticity and driving. We observe that fragmentation plays a relevant role in the shape of the velocity distribution of the particles. When the fragmentation is driven by local stochastic events, the long velocity tail is essentially exponential independently of the heating frequency and the breaking rule. However, for a Lowe-Andersen thermostat, numerical evidence strongly supports the conjecture that the scaled velocity distribution follows a generalized exponential behavior f(c) approximately exp(-cn) , with n approximately 1.2 , regarding less the fragmentation mechanisms. PMID:18643255

  6. Noble gases in meteorites and terrestrial planets

    NASA Technical Reports Server (NTRS)

    Wacker, J. F.

    1985-01-01

    Terrestrial planets and chondrites have noble gas platforms that are sufficiently alike, especially Ne/Ar, that they may have acquired their noble gases by similar processes. Meteorites presumably obtained their noble gases during formation in the solar nebula. Adsorption onto C - the major gas carrier in chondrites - is the likely mechanism for trapping noble gases; recent laboratory simulations support this hypothesis. The story is more complex for planets. An attractive possibility is that the planets acquired their noble gases in a late accreting veneer of chondritic material. In chondrites, noble gases correlate with C, N, H, and volatile metals; by Occam's Razor, we would expect a similar coupling in planets. Indeed, the Earth's crust and mantle contain chondritic like trace volatiles and PL group metals, respectively and the Earth's oceans resemble C chondrites in their enrichment of D (8X vs 8-10X of the galactic D/H ratio). Models have been proposed to explain some of the specific noble gas patterns in planets. These include: (1) noble gases may have been directly trapped by preplanetary material instead of arriving in a veneer; (2) for Venus, irradiation of preplanetary material, followed by diffusive loss of Ne, could explain the high concentration of AR-36; (3) the Earth and Venus may have initially had similar abundances of noble gases, but the Earth lost its share during the Moon forming event; (4) noble gases could have been captured by planetestimals, possibly leading to gravitational fractionation, particularly of Xe isotopes and (5) noble gases may have been dissolved in the hot outer portion of the Earth during contact with a primordial atmosphere.

  7. Remote monitoring of volcanic gases using passive Fourier transform spectroscopy

    SciTech Connect

    Love, S.P.; Goff, F.; Counce, D.; Schmidt, S.C.; Siebe, C.; Delgado, H.

    1999-06-01

    Volcanic gases provide important insights on the internal workings of volcanoes and changes in their composition and total flux can warn of impending changes in a volcano`s eruptive state. In addition, volcanoes are important contributors to the earth`s atmosphere, and understanding this volcanic contribution is crucial for unraveling the effect of anthropogenic gases on the global climate. Studies of volcanic gases have long relied upon direct in situ sampling, which requires volcanologists to work on-site within a volcanic crater. In recent years, spectroscopic techniques have increasingly been employed to obtain information on volcanic gases from greater distances and thus at reduced risk. These techniques have included UV correlation spectroscopy (Cospec) for SO{sub 2} monitoring, the most widely-used technique, and infrared spectroscopy in a variety of configurations, both open- and closed-path. Francis et al. have demonstrated good results using the sun as the IR source. This solar occultation technique is quite useful, but puts rather strong restrictions on the location of instrument and is thus best suited to more accessible volcanoes. In order to maximize the flexibility and range of FTIR measurements at volcanoes, work over the last few years has emphasized techniques which utilize the strong radiance contrast between the volcanic gas plume and the sky. The authors have successfully employed these techniques at several volcanoes, including the White Island and Ruapehu volcanoes in New Zealand, the Kilauea volcano on Hawaii, and Mt. Etna in Italy. But Popocatepetl (5452 m), the recently re-awakened volcano 70 km southeast of downtown Mexico City, has provided perhaps the best examples to date of the usefulness of these techniques.

  8. Light Collection in Liquid Noble Gases

    SciTech Connect

    McKinsey, Dan

    2013-05-29

    Liquid noble gases are increasingly used as active detector materials in particle and nuclear physics. Applications include calorimeters and neutrino oscillation experiments as well as searches for neutrinoless double beta decay, direct dark matter, muon electron conversion, and the neutron electric dipole moment. One of the great advantages of liquid noble gases is their copious production of ultraviolet scintillation light, which contains information about event energy and particle type. I will review the scintillation properties of the various liquid noble gases and the means used to collect their scintillation light, including recent advances in photomultiplier technology and wavelength shifters.

  9. Radiation and combined heat transfer in channels

    SciTech Connect

    Tamonis, M.

    1987-01-01

    This book is a concise, practical treatment of numerical methods of calculation for radiative and combined (convection and conduction) heat transfer -- encompassing channel flows of radiating and nonradiating media. The volume offers results from calculations for various flow conditions, and analyzes methods used in determining the spectral optical properties of molecular gases. Topics considered include optical properties of molecular gases, transfer equations for combined heat transfer, experimental techniques, convective heat transfer in heat gas flows, radiative heat transfer in gaseous media, combined heat transfer, and radiative and combined heat transfer in applied problems.

  10. Radiation and combined heat transfer in channels

    SciTech Connect

    Tamonis, M.

    1986-01-01

    This book presents numerical methods of calculation of radiative and combined heat transfer in channel flows of radiating as well as nonradiating media. Results obtained in calculations for flow conditions of combustion products from organic fuel products are given and methods used in determining the spectral optical properties of molecular gases are analyzed. The book presents applications of heat transfer in solving problems. Topic covered are as follows: optical properties of molecular gases; transfer equations for combined heat transfer; experimental technique; convective heat transfer in heated gas flows; radiative heat transfer in gaseous media; combined heat transfer; and radiative and combined heat transfer in applied problems.

  11. Detailed Investigations of Interactions between Ionizing Radiation and Neutral Gases

    SciTech Connect

    Landers, Allen L

    2014-03-31

    We are investigating phenomena that stem from the many body dynamics associated with ionization of an atom or molecule by photon or charged particle. Our program is funded through the Department of Energy EPSCoR Laboratory Partnership Award in collaboration with Lawrence Berkeley National Laboratory. We are using variations on the well established COLTRIMS technique to measure ions and electrons ejected during these interactions. Photoionization measurements take place at the Advanced Light Source at LBNL as part of the ALS-COLTRIMS collaboration with the groups of Reinhard Dörner at Frankfurt and Ali Belkacem at LBNL. Additional experiments on charged particle impact are conducted locally at Auburn University where we are studying the dissociative molecular dynamics following interactions with either ions or electrons over a velocity range of 1 to 12 atomic units.

  12. Prognostic Importance of Gleason 7 Disease Among Patients Treated With External Beam Radiation Therapy for Prostate Cancer: Results of a Detailed Biopsy Core Analysis

    SciTech Connect

    Spratt, Daniel E.; Zumsteg, Zach; Ghadjar, Pirus; Pangasa, Misha; Pei, Xin; Fine, Samson W.; Yamada, Yoshiya; Kollmeier, Marisa; Zelefsky, Michael J.

    2013-04-01

    Purpose: To analyze the effect of primary Gleason (pG) grade among a large cohort of Gleason 7 prostate cancer patients treated with external beam radiation therapy (EBRT). Methods and Materials: From May 1989 to January 2011, 1190 Gleason 7 patients with localized prostate cancer were treated with EBRT at a single institution. Of these patients, 613 had a Gleason 7 with a minimum of a sextant biopsy with nonfragmented cores and full biopsy core details available, including number of cores of cancer involved, percentage individual core involvement, location of disease, bilaterality, and presence of perineural invasion. Median follow-up was 6 years (range, 1-16 years). The prognostic implication for the following outcomes was analyzed: biochemical recurrence-free survival (bRFS), distant metastasis-free survival (DMFS), and prostate cancer-specific mortality (PCSM). Results: The 8-year bRFS rate for pG3 versus pG4 was 77.6% versus 61.3% (P<.0001), DMFS was 96.8% versus 84.3% (P<.0001), and PCSM was 3.7% versus 8.1% (P=.002). On multivariate analysis, pG4 predicted for significantly worse outcome in all parameters. Location of disease (apex, base, mid-gland), perineural involvement, maximum individual core involvement, and the number of Gleason 3+3, 3+4, or 4+3 cores did not predict for distant metastases. Conclusions: Primary Gleason grade 4 independently predicts for worse bRFS, DMFS, and PCSM among Gleason 7 patients. Using complete core information can allow clinicians to utilize pG grade as a prognostic factor, despite not having the full pathologic details from a prostatectomy specimen. Future staging and risk grouping should investigate the incorporation of primary Gleason grade when complete biopsy core information is used.

  13. Greenhouse effects due to man-made perturbations of trace gases

    NASA Technical Reports Server (NTRS)

    Wang, W. C.; Yung, Y. L.; Lacis, A. A.; Mo, T.; Hansen, J. E.

    1976-01-01

    Nitrous oxide, methane, ammonia, and a number of other trace constituents of the earth's atmosphere have infrared absorption bands in the spectral range from 7 to 14 microns. Despite their small amounts, these gases can have a significant effect on the thermal structure of the atmosphere by transmitting most of the thermal radiation from the earth's surface to the lower atmosphere. In the present paper, this greenhouse effect is computed for a number of trace gases. The nature and climatic implications of possible changes in the concentrations of N2O, CH4, NH3, and HNO3 are discussed.

  14. Collective modes in cold paramagnetic gases

    SciTech Connect

    Andreeva, T L; Rubin, P L

    2014-02-28

    We have obtained a condition for the emergence of spin waves in paramagnetic gases Re >> ImÂ, which is fulfilled only at temperatures of the order of 1 ?K. (laser applications and other topics in quantum electronics)

  15. 40 CFR 90.312 - Analytical gases.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... a concentration of propane higher than what a gas supplier considers to be safe may be substituted... within ±two percent. (d) Oxygen interference check gases must contain propane with 350 ppmC ±75...

  16. 40 CFR 91.312 - Analytical gases.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... contains a concentration of propane higher than what a gas supplier considers to be safe may be substituted... within ±2 percent. (d) Oxygen interference check gases must contain propane with 350 ppmC ±75...

  17. 40 CFR 90.312 - Analytical gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... a concentration of propane higher than what a gas supplier considers to be safe may be substituted... within ±two percent. (d) Oxygen interference check gases must contain propane with 350 ppmC ±75...

  18. 40 CFR 90.312 - Analytical gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... a concentration of propane higher than what a gas supplier considers to be safe may be substituted... within ±two percent. (d) Oxygen interference check gases must contain propane with 350 ppmC ±75...

  19. 40 CFR 92.112 - Analytical gases.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... as the diluent. (b) Gases for the hydrocarbon analyzer shall be single blends of propane using zero... propane at a concentration greater than 50 percent of range. The concentration value shall be...

  20. 40 CFR 90.312 - Analytical gases.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... a concentration of propane higher than what a gas supplier considers to be safe may be substituted... within ±two percent. (d) Oxygen interference check gases must contain propane with 350 ppmC ±75...

  1. Comparing greenhouse gases for policy purposes

    E-print Network

    Schmalensee, Richard

    1993-01-01

    In order to derive optimal policies for greenhouse gas emissions control, the discounted marginal damages of emissions of different gases must be compared. The greenhouse warming potential (GWP) index, which is most often ...

  2. Denitrification of combustion gases. [Patent application

    DOEpatents

    Yang, R.T.

    1980-10-09

    A method for treating waste combustion gas to remove the nitrogen oxygen gases therefrom is disclosed wherein the waste gas is first contacted with calcium oxide which absorbs and chemically reacts with the nitrogen oxide gases therein at a temperature from about 100/sup 0/ to 430/sup 0/C. The thus reacted calcium oxide (now calcium nitrate) is then heated at a temperature range between about 430/sup 0/ and 900/sup 0/C, resulting in regeneration of the calcium oxide and production of the decomposition gas composed of nitrogen and nitrogen oxide gas. The decomposition gases can be recycled to the calcium oxide contacting step to minimize the amount of nitrogen oxide gases in the final product gas.

  3. 40 CFR 1065.750 - Analytical gases.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES...Purified Gases 1 Constituent Purified air Purified N2 THC (C1 -equivalent...1065.1010). (ii) FID burner air. Use FID burner air that...

  4. 40 CFR 92.112 - Analytical gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test...be single blends of propane using zero grade air as the diluent. (c) Gases for the...

  5. Voluntary reporting of greenhouse gases, 1995

    SciTech Connect

    1996-07-01

    The Voluntary Reporting Program for greenhouse gases is part of an attempt by the U.S. Government to develop innovative, low-cost, and nonregulatory approaches to limit emissions of greenhouse gases. It is one element in an array of such programs introduced in recent years as part of the effort being made by the United States to comply with its national commitment to stabilize emissions of greenhouse gases under the Framework Convention on Climate Change. The Voluntary Reporting Program, developed pursuant to Section 1605(b) of the Energy Policy Act of 1992, permits corporations, government agencies, households, and voluntary organizations to report to the Energy Information Administration (EIA) on actions taken that have reduced or avoided emissions of greenhouse gases.

  6. Nonhydrodynamic Transport in Trapped Unitary Fermi Gases.

    PubMed

    Brewer, Jasmine; Romatschke, Paul

    2015-11-01

    Many strongly coupled fluids are known to share similar hydrodynamic transport properties. In this work we argue that this similarity could extend beyond hydrodynamics to transient dynamics through the presence of nonhydrodynamic modes. We review nonhydrodynamic modes in kinetic theory and gauge-gravity duality and discuss their signatures in trapped Fermi gases close to unitarity. Reanalyzing previously published experimental data we find hints of nonhydrodynamic modes in cold Fermi gases in two and three dimensions. PMID:26588365

  7. Nonhydrodynamic Transport in Trapped Unitary Fermi Gases

    NASA Astrophysics Data System (ADS)

    Brewer, Jasmine; Romatschke, Paul

    2015-11-01

    Many strongly coupled fluids are known to share similar hydrodynamic transport properties. In this work we argue that this similarity could extend beyond hydrodynamics to transient dynamics through the presence of nonhydrodynamic modes. We review nonhydrodynamic modes in kinetic theory and gauge-gravity duality and discuss their signatures in trapped Fermi gases close to unitarity. Reanalyzing previously published experimental data we find hints of nonhydrodynamic modes in cold Fermi gases in two and three dimensions.

  8. Biological production of products from waste gases

    DOEpatents

    Gaddy, James L. (Fayetteville, AR)

    2002-01-22

    A method and apparatus are designed for converting waste gases from industrial processes such as oil refining, and carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various products, such as organic acids, alcohols, hydrogen, single cell protein, and salts of organic acids by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified.

  9. Mesospheric removal of very long-lived greenhouse gases SF6 and CFC-115 by metal reactions, Lyman-? photolysis, and electron attachment.

    PubMed

    Totterdill, Anna; Kovács, Tamás; Gómez Martín, Juan Carlos; Feng, Wuhu; Plane, John M C

    2015-03-12

    The fluorinated gases SF6 and C2F5Cl (CFC-115) are chemically inert with atmospheric lifetimes of many centuries which, combined with their strong absorption of IR radiation, results in unusually high global warming potentials. Very long lifetimes imply that mesospheric sinks could make important contributions to their atmospheric removal. In order to investigate this, the photolysis cross sections at the prominent solar Lyman-? emission line (121.6 nm), and the reaction kinetics of SF6 and CFC-115 with the neutral meteoric metal atoms Na, K, Mg, and Fe over large temperature ranges, were measured experimentally. The Na and K reactions exhibit significant non-Arrhenius behavior; quantum chemistry calculations of the potential energy surfaces for the SF6 reactions indicate that the Na and K reactions with SF6 are probably activated by vibrational excitation of the F-SF5 (v3) stretching mode. A limited set of kinetic measurements on Na + SF5CF3 are also presented. The atmospheric removal of these long-lived gases by a variety of processes is then evaluated. For SF6, the removal processes in decreasing order of importance are electron attachment, VUV photolysis, and reaction with K, Na, and H. For CFC-115, the removal processes in decreasing order of importance are reaction with O((1)D), VUV photolysis, and reaction with Na, K, and H. PMID:25647411

  10. Classification and generation of terrestrial rare gases

    NASA Technical Reports Server (NTRS)

    Saito, K.

    1978-01-01

    A Kr-84/Xe-130 versus Ne-20/Ar-36 diagram is a very useful format with which to study the elemental ratios of rare gases from terrestrial materials. It can separate not only the three types of rare gases which Ozima and Alexander (1976) classified but also the 'planetary' type rare gases from the other three types of rare gases. When all the available terrestrial rare gas data are plotted in a Kr-84/Xe-130 versus Ne-20/Ar-36 diagram, several observations can be made. First, most of the analyses of rare gases from shales yield Kr-84/Xe-130 ratios between the 'planetary' and atmospheric values. If, however, the atmosphere's high Kr-84/Xe-130 ratio was produced by the selective adsorption of xenon onto shales from an initially 'planetary' atmosphere, as is widely accepted, then the Kr-84/Xe-130 ratio in shales should be even lower than the 'planetary' value. Second, the rare gas pattern in the quenched rims of submarine basalts may be explained as fractionated samples of the rare gases in sea water.

  11. Source gases: Concentrations, emissions, and trends

    NASA Technical Reports Server (NTRS)

    Fraser, Paul J.; Harriss, Robert; Penkett, Stuart A.; Makide, Yoshihiro; Sanhueza, Eugenio; Alyea, Fred N.; Rowland, F. Sherwood; Blake, Don; Sasaki, Toru; Cunnold, Derek M.

    1991-01-01

    Source gases are defined as those gases that influence levels of stratospheric ozone (O3) by transporting species containing halogen, hydrogen, and nitrogen to the stratosphere. Examples are the CFC's, methane (CH4), and nitrous oxide (N2O). Other source gases that also come under consideration in an atmospheric O3 context are those that are involved in the O3 or hydroxyl (OH) radical chemistry of the troposphere. Examples are CH4, carbon monoxide (CO), and nonmethane hydrocarbons (NMHC's). Most of the source gases, along with carbon dioxide (CO2) and water vapor (H2O), are climatically significant and thus affect stratospheric O3 levels by their influence on stratospheric temperatures. Carbonyl sulphide (COS) could affect stratospheric O3 through maintenance of the stratospheric sulphate aerosol layer, which may be involved in heterogeneous chlorine-catalyzed O3 destruction. The previous reviews of trends and emissions of source gases, either from the context of their influence on atmospheric O3 or global climate change, are updated. The current global abundances and concentration trends of the trace gases are given in tabular format.

  12. Analysis of electron interactions in dielectric gases

    SciTech Connect

    Olivet, Aurelio; Duque, Daniel; Vega, Lourdes F.

    2007-01-15

    We present and discuss results concerning electron interactions processes of dielectric gases and their relationship with the macroscopic behavior of these gases, in particular, with their dielectric strength. Such analysis is based on calculating energies of reactions for molecular ionization, dissociative ionization, parent negative ion formation, and dissociative electron attachment processes. We hypothesize that the estimation of the required energy for a reduced number of processes that take place in electrically stressed gases could be related to the gas' capability to manage the electron flow during an electrical discharge. All calculations were done with semiempirical quantum chemistry methods, including an initial optimization of molecular geometry and heat of formation of the dielectric gases and all of species that appear during electron interaction reactions. The performance of semiempirical methods Austin model 1 and Parametric model 3 (PM3) was compared for several compounds, PM3 being superior in most cases. Calculations performed for a sample of nine dielectric gases show that electron attachment and detachment processes occur in different energy bands that do not overlap for any value of the dielectric strength. We have also analyzed the relationship between dielectric strength and two physical properties: electron affinity and ionization energy. Calculations performed for 43 dielectric gases show no clear correlation between them, although certain guidelines for the qualitative estimation of dielectric strength can still be assessed.

  13. The Continual Intercomparison of Radiation Codes (CIRC) Assessing Anew the Quality of GCM Radiation Algorithms

    NASA Technical Reports Server (NTRS)

    Oreopoulos, Lazaros; Mlawer, Eli

    2010-01-01

    The simulation of changes in the Earth's climate due to solar and thermal radiative processes with global climate models (GCMs) is highly complex, depending on the parameterization of a multitude of nonlinearly coupled physical processes. In contrast, the germ of global climate change, the radiative forcing from enhanced abundances of greenhouse gases, is relatively well understood. The impressive agreement between detailed radiation calculations and highly resolved spectral radiation measurements in the thermal infrared under cloudless conditions (see, for example, Fig. 1) instills confidence in our knowledge of the sources of gaseous absorption. That the agreement spans a broad range of temperature and humidity regimes using instruments mounted on surface, aircraft, and satellite platforms not only attests to our capability to accurately calculate radiative fluxes under present conditions, but also provides confidence in the spectroscopic basis for computation of fluxes under conditions that might characterize future global climate (e.g., radiative forcing). Alas, the computational costs of highly resolved spectral radiation calculations cannot be afforded presently in GCMs. Such calculations have instead been used as the foundation for approximations implemented in fast but generally less accurate algorithms performing the needed radiative transfer (RT) calculations in GCMs. Credible climate simulations by GCMs cannot be ensured without accurate solar and thermal radiative flux calculations under all types of sky conditions: pristine cloudless, aerosol-laden, and cloudy. The need for accuracy in RT calculations is not only important for greenhouse gas forcing scenarios, but is also profoundly needed for the robust simulation of many other atmospheric phenomena, such as convective processes.

  14. Biogenic and anthropogenic trace gases in the atmosphere

    NASA Technical Reports Server (NTRS)

    Brasseur, G. P.; Prinn, R. G.

    1992-01-01

    This paper illustrates the importance of biogenic and anthropogenic trace gases for the global environment and for the climate system. The paper briefly reviews the currently available estimates of sources and strengths of the biogenic and anthropogenic gases on the global scale. One of the major concerns for the global environment is the rapid increase in the concentration of long-lived trace gases such as CO2, CH4, N2O and the chlorofluorocarbons. The trend in the carbon dioxide concentration, as a result of fossil-fuel burning, is of the order of 0.4 percent per year, and this trend is related to the CO2 uptake by the ocean and by terrestrial ecosystems, which are likely to be modified if the planet warms up in the forthcoming decades. The concentrations of methane and nitrous oxide are increasing by 0.9 and 0.25 percent per year, respectively. In the case of the most widely used chlorofluorocarbons, trends as large as 10 percent per year or more are being measured.

  15. Emissions of greenhouse gases in the United States 1996

    SciTech Connect

    1997-10-01

    The Energy Information Administration (EIA) is required by the Energy Policy Act of 1992 to prepare a report on aggregate US national emissions of greenhouse gases for the period 1987--1990, with annual updates thereafter. This report is the fifth annual update, covering national emissions over the period 1989--1995, with preliminary estimates of emissions for 1996. The estimates contained in this report have been revised from those in last year`s report. Emissions estimates for carbon dioxide are reported in metric tons of carbon; estimates for other gases are reported in metric tons of gas. Chapter 1 of this report briefly recapitulates some background information about global climate change and the greenhouse effect and discusses important recent developments in global climate change activities. Chapter 2 through 6 cover emissions of carbon dioxide, methane, nitrous oxide, halocarbons, and criteria pollutants, respectively. Chapter 7 describes potential sequestration and emissions of greenhouse gases as a result of land use changes. Five appendixes are included with this report. 216 refs., 11 figs., 38 tabs.

  16. Experimental Research of Pyrolysis Gases Cracking on Surface of Charcoal

    NASA Astrophysics Data System (ADS)

    Kosov, Valentin; Kosov, Vladimir; Zaichenko, Victor

    For several years, in the Joint Institute for High Temperatures of Russian Academy of Sciences, two-stage technology of biomass processing has been developing [1]. The technology is based on pyrolysis of biomass as the first stage. The second stage is high-temperature conversion of liquid fraction of the pyrolysis on the surface of porous charcoal matrix. Synthesis gas consisted of carbon monoxide and hydrogen is the main products of the technology. This gas is proposed to be used as fuel for gas-engine power plant. For practical implementation of the technology it is important to know the size of hot char filter for full cracking of the pyrolysis gases on the surface of charcoal. Theoretical determination of the cracking parameters of the pyrolysis gases on the surface of coal is extremely difficult because the pyrolysis gases include tars, whose composition and structure is complicated and depends on the type of initial biomass. It is also necessary to know the surface area of the char used in the filter, which is also a difficult task. Experimental determination of the hot char filter parameters is presented. It is shown that proposed experimental method can be used for different types of biomass.

  17. Atmospheric Radiation Measurement Climate Research Facility (ACRF) Annual Report 2008

    SciTech Connect

    LR Roeder

    2008-12-01

    The Importance of Clouds and Radiation for Climate Change: The Earth’s surface temperature is determined by the balance between incoming solar radiation and thermal (or infrared) radiation emitted by the Earth back to space. Changes in atmospheric composition, including greenhouse gases, clouds, and aerosols, can alter this balance and produce significant climate change. Global climate models (GCMs) are the primary tool for quantifying future climate change; however, there remain significant uncertainties in the GCM treatment of clouds, aerosol, and their effects on the Earth’s energy balance. In 1989, the U.S. Department of Energy (DOE) Office of Science created the Atmospheric Radiation Measurement (ARM) Program to address scientific uncertainties related to global climate change, with a specific focus on the crucial role of clouds and their influence on the transfer of radiation in the atmosphere. To reduce these scientific uncertainties, the ARM Program uses a unique twopronged approach: • The ARM Climate Research Facility, a scientific user facility for obtaining long-term measurements of radiative fluxes, cloud and aerosol properties, and related atmospheric characteristics in diverse climate regimes; and • The ARM Science Program, focused on the analysis of ACRF and other data to address climate science issues associated with clouds, aerosols, and radiation, and to improve GCMs. This report provides an overview of each of these components and a sample of achievements for each in fiscal year (FY) 2008.

  18. Infrared band absorptance correlations and applications to nongray radiation. [mathematical models of absorption spectra for nongray atmospheres in order to study air pollution

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Manian, S. V. S.

    1976-01-01

    Various mathematical models for infrared radiation absorption spectra for atmospheric gases are reviewed, and continuous correlations for the total absorptance of a wide band are presented. Different band absorptance correlations were employed in two physically realistic problems (radiative transfer in gases with internal heat source, and heat transfer in laminar flow of absorbing-emitting gases between parallel plates) to study their influence on final radiative transfer results. This information will be applied to the study of atmospheric pollutants by infrared radiation measurement.

  19. 40 CFR 86.514-78 - Analytical gases.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Later New Motorcycles; Test Procedures § 86.514-78 Analytical gases. (a) Analyzer gases. (1) Gases for the CO and CO2 analyzers shall be single blends of CO and CO2 respectively using nitrogen as the diluent. (2) Gases for the THC analyzer shall be: (i) Single blends of propane using air as the...

  20. 40 CFR 86.514-78 - Analytical gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Later New Motorcycles; Test Procedures § 86.514-78 Analytical gases. (a) Analyzer gases. (1) Gases for the CO and CO2 analyzers shall be single blends of CO and CO2 respectively using nitrogen as the diluent. (2) Gases for the THC analyzer shall be: (i) Single blends of propane using air as the...

  1. 40 CFR 86.514-78 - Analytical gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Later New Motorcycles; Test Procedures § 86.514-78 Analytical gases. (a) Analyzer gases. (1) Gases for the CO and CO2 analyzers shall be single blends of CO and CO2 respectively using nitrogen as the diluent. (2) Gases for the THC analyzer shall be: (i) Single blends of propane using air as the...

  2. 40 CFR 86.514-78 - Analytical gases.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Later New Motorcycles; Test Procedures § 86.514-78 Analytical gases. (a) Analyzer gases. (1) Gases for the CO and CO2 analyzers shall be single blends of CO and CO2 respectively using nitrogen as the diluent. (2) Gases for the THC analyzer shall be: (i) Single blends of propane using air as the...

  3. 40 CFR 86.514-78 - Analytical gases.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Later New Motorcycles; Test Procedures § 86.514-78 Analytical gases. (a) Analyzer gases. (1) Gases for the CO and CO2 analyzers shall be single blends of CO and CO2 respectively using nitrogen as the diluent. (2) Gases for the THC analyzer shall be: (i) Single blends of propane using air as the...

  4. BIOSIGNATURE GASES IN H{sub 2}-DOMINATED ATMOSPHERES ON ROCKY EXOPLANETS

    SciTech Connect

    Seager, S.; Bains, W.; Hu, R.

    2013-11-10

    Super-Earth exoplanets are being discovered with increasing frequency and some will be able to retain stable H{sub 2}-dominated atmospheres. We study biosignature gases on exoplanets with thin H{sub 2} atmospheres and habitable surface temperatures, using a model atmosphere with photochemistry and a biomass estimate framework for evaluating the plausibility of a range of biosignature gas candidates. We find that photochemically produced H atoms are the most abundant reactive species in H{sub 2} atmospheres. In atmospheres with high CO{sub 2} levels, atomic O is the major destructive species for some molecules. In Sun-Earth-like UV radiation environments, H (and in some cases O) will rapidly destroy nearly all biosignature gases of interest. The lower UV fluxes from UV-quiet M stars would produce a lower concentration of H (or O) for the same scenario, enabling some biosignature gases to accumulate. The favorability of low-UV radiation environments to accumulate detectable biosignature gases in an H{sub 2} atmosphere is closely analogous to the case of oxidized atmospheres, where photochemically produced OH is the major destructive species. Most potential biosignature gases, such as dimethylsulfide and CH{sub 3}Cl, are therefore more favorable in low-UV, as compared with solar-like UV, environments. A few promising biosignature gas candidates, including NH{sub 3} and N{sub 2}O, are favorable even in solar-like UV environments, as these gases are destroyed directly by photolysis and not by H (or O). A more subtle finding is that most gases produced by life that are fully hydrogenated forms of an element, such as CH{sub 4} and H{sub 2}S, are not effective signs of life in an H{sub 2}-rich atmosphere because the dominant atmospheric chemistry will generate such gases abiologically, through photochemistry or geochemistry. Suitable biosignature gases in H{sub 2}-rich atmospheres for super-Earth exoplanets transiting M stars could potentially be detected in transmission spectra with the James Webb Space Telescope.

  5. Thermodynamic design principle of mixed-gases Kleemenko refrigeration cycles

    NASA Astrophysics Data System (ADS)

    Gong, M. Q.; Luo, E. C.; Wu, J. F.; Zhou, Y.

    2002-05-01

    Mixed-gases throttling refrigeration cycles are recuperative cycles. The refrigeration system has at least one heat exchanger and from zero to three or more phase separators. Detailed discussions are made in this paper on the thermodynamic performance of several cycles, including extensive simulations and optimizations of mixtures, operating parameters of pressures, and flow configurations. The results show that the mixed refrigerant is the most important design parameter that influences the performance of the system. From a thermodynamic point of view, the configurations that were studied can all achieve about the same efficiency with an appropriate selection of the mixture and operating pressures.

  6. Gases as Idealized Lattices: A Rational Reconstruction of Students' Understanding of the Behavior of Gases.

    ERIC Educational Resources Information Center

    Niaz, Mansoor

    2000-01-01

    Establishes a relationship between students' understanding of gases and its parallels in the history of science. Finds that college freshman students' alternative conceptions about gas behavior are resistant to change and recapitulate theories scientists held in the past, such as the Lattice Theory of Gases. (Contains 52 references.) (Author/WRM)

  7. Quantified estimates of total GWPs for greenhouse gases taking into account tropospheric chemistry

    SciTech Connect

    Wuebbles, D.J.; Tamaresis, J.S.; Patten, K.O.

    1993-11-01

    The purpose of this report is to give interim account of the progress being made at Lawrence Livermore National Laboratory (LLNL) in developing an improved capability for assessing the direct and indirect effects on Global Warming Potentials. Much of our current efforts are being devoted to improving the capability for modeling of global tropospheric processes in our state-of-the-art zonally-averaged chemical-radiative-transport model of the troposphere and stratosphere. These efforts are in preparation for an improved evaluation and better quantification of the indirect GWPs resulting from effects on tropospheric ozone from ethane and other gases with significant human-related emissions. There are three major findings that should result from this project that should have significant impacts on EPA and its programs. First, the current and ongoing studies of the direct and indirect GWPs should have a significant influence on the continuing national and international assessments of climate change. Second, the improved capability for modeling of chemical and physical processes should lead to enhanced understanding of the controlling factors influencing ozone, hydroxyl and other key tropospheric constituents. Third, the enhanced modeling capability should be important to future studies of human-related influences on tropospheric and stratospheric chemical processes.

  8. Where do California's greenhouse gases come from?

    ScienceCinema

    Fischer, Marc

    2013-05-29

    Last March, more than two years after California passed legislation to slash greenhouse gas emissions 25 percent by 2020, Lawrence Berkeley National Laboratory scientist Marc Fischer boarded a Cessna loaded with air monitoring equipment and crisscrossed the skies above Sacramento and the Bay Area. Instruments aboard the aircraft measured a cocktail of greenhouse gases: carbon dioxide from fossil fuel use, methane from livestock and landfills, CO2 from refineries and power plants, traces of nitrous oxide from agriculture and fuel use, and industrially produced other gases like refrigerants. The flight was part of the Airborne Greenhouse Gas Emissions Survey, a collaboration between Berkeley Lab, the National Oceanic and Atmospheric Administration, and the University of California, and UC Davis to pinpoint the sources of greenhouse gases in central California. The survey is intended to improve inventories of the states greenhouse gas emissions, which in turn will help scientists verify the emission reductions mandated by AB-32, the legislation enacted by California in 2006.

  9. Rare gases in cyclosilicates and cogenetic minerals

    NASA Technical Reports Server (NTRS)

    Saito, K.; Alexander, E. C., Jr.; Dragon, J. C.; Zashu, S.

    1984-01-01

    The cyclosilicate minerals, beryl, tourmaline, and cordierite, typically contain large amounts of He-4 and Ar-40 which are not in situ radiogenic products. In the study of excess rare gases in cyclosilicates, one of the most enigmatic observations is the age effect, a qualitative tendency for geologically older samples to contain more excess He-4 and Ar-40 than younger samples. The present investigation is concerned with measurements regarding the abundance and isotopic composition of all five rare gases in a number of cyclosilicates as well as in their cogenetic minerals. The significance of the obtained data is discussed. The data indicate that cyclosilicates sample the rare gases present in the environment in which they crystallize. This 'sampling' involves major elemental fractionations which are variable but mineral specific. Cyclosilicates can, therefore, be used to probe the isotopic ratios and elemental compositions.

  10. Numerical study of radiation effect on the municipal solid waste combustion characteristics inside an incinerator.

    PubMed

    Wang, Jingfu; Xue, Yanqing; Zhang, Xinxin; Shu, Xinran

    2015-10-01

    Due to its advantages of high degree volume reduction, relatively stable residue, and energy reclamation, incineration becomes one of the best choices for Municipal Solid Waste (MSW) disposal. However, detailed measurements of temperature and gas species inside a furnace are difficulty by conventional experimental techniques. Therefore, numerical simulation of MSW incineration in the packed bed and gas flow field was applied. In this work, a three dimensional (3-D) model of incinerator system, including flow, heat transfer, detailed chemical mechanisms, and non-gray gas models, was developed. Radiation from the furnace wall and the flame formed above the bed is of importance for drying and igniting the waste. The preheated air with high temperature is used for the MSW combustion. Under the conditions of high temperature and high pressure, MSW combustion produces a variety of radiating gases. The wavelength-depend radiative properties of flame adopted in non-gray radiation model were obtained from a statistical narrow-band model. The influence of radiative heat transfer on temperature, flow field is researched by adiabatic model (without considering radiation), gray radiation model, and non-gray radiation model. The simulation results show that taking into account the non-gray radiation is essential. PMID:26233882

  11. Comparison of driving gases for IABPs.

    PubMed

    Kayser, K L; Johnson, W D; Shore, R T

    1981-01-01

    Several aspects of CO2 vs He as the driving gas in intra-aortic balloon counterpulsation systems were reviewed and investigated. Carbon dioxide seems to be significantly safer than other gases, but not benign. Helium produces a faster balloon response, but the physiologic significance has not been defined. Balloon driving gases become diluted in relatively short time. Leak detection systems have significant limitations. It seems prudent for users of dual-balloon systems to periodically measure the PCO2 of the driving gas. A better method of purging the single-balloon system was developed. PMID:6785559

  12. Composition of gases vented from a condenser

    SciTech Connect

    Lyon, R.N.

    1980-08-01

    Designers of systems that involve condensers often need to predict the amount of process vapor that accompanies the noncondensable gases that are vented from the condensers. An approximation is given that appears to provide, in many cases, reasonably accurate values for the mole ratio of process vapor to noncondensable gases in the vented mixture. The approximation is particularly applicable to flash and direct-contact power systems for geothermal brines and ocean thermal energy conversion (OTEC). More regorous relationships are available for exceptional cases.

  13. Stationary light in cold atomic gases

    E-print Network

    Gor Nikoghosyan; Michael Fleischhauer

    2009-09-16

    We discuss stationary light created by a pair of counter-propagating control fields in Lambda-type atomic gases with electromagnetically induced transparency for the case of negligible Doppler broadening. In this case the secular approximation used in the discussion of stationary light in hot vapors is no longer valid. We discuss the quality of the effective light-trapping system and show that in contrast to previous claims it is finite even for vanishing ground-state dephasing. The dynamics of the photon loss is in general non exponential and can be faster or slower than in hot gases.

  14. Seeing spin dynamics in atomic gases

    E-print Network

    Dan M. Stamper-Kurn

    2014-12-31

    The dynamics of internal spin, electronic orbital, and nuclear motion states of atoms and molecules have preoccupied the atomic and molecular physics community for decades. Increasingly, such dynamics are being examined within many-body systems composed of atomic and molecular gases. Our findings sometimes bear close relation to phenomena observed in condensed-matter systems, while on other occasions they represent truly new areas of investigation. I discuss several examples of spin dynamics that occur within spinor Bose-Einstein gases, highlighting the advantages of spin-sensitive imaging for understanding and utilizing such dynamics.

  15. Measuring Viscosities of Gases at Atmospheric Pressure

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Mall, Gerald H.; Hoshang, Chegini

    1987-01-01

    Variant of general capillary method for measuring viscosities of unknown gases based on use of thermal mass-flowmeter section for direct measurement of pressure drops. In technique, flowmeter serves dual role, providing data for determining volume flow rates and serving as well-characterized capillary-tube section for measurement of differential pressures across it. New method simple, sensitive, and adaptable for absolute or relative viscosity measurements of low-pressure gases. Suited for very complex hydrocarbon mixtures where limitations of classical theory and compositional errors make theoretical calculations less reliable.

  16. Temporally multiplexed quantum repeaters with atomic gases

    SciTech Connect

    Simon, Christoph; Riedmatten, Hugues de; Afzelius, Mikael

    2010-07-15

    We propose a temporally multiplexed version of the Duan-Lukin-Cirac-Zoller (DLCZ) quantum-repeater protocol using controlled inhomogeneous spin broadening in atomic gases. A first analysis suggests that the advantage of multiplexing is negated by noise due to spin-wave excitations corresponding to unobserved directions of Stokes photon emission. However, this problem can be overcome with the help of a moderate-finesse cavity which is in resonance with Stokes photons, but invisible to the anti-Stokes photons. Our proposal promises greatly enhanced quantum repeater performance with atomic gases.

  17. Oxidation of ultrathin GaSe

    NASA Astrophysics Data System (ADS)

    Beechem, Thomas E.; Kowalski, Brian M.; Brumbach, Michael T.; McDonald, Anthony E.; Spataru, Catalin D.; Howell, Stephen W.; Ohta, Taisuke; Pask, Jesse A.; Kalugin, Nikolai G.

    2015-10-01

    Oxidation of exfoliated gallium selenide (GaSe) is investigated through Raman, photoluminescence, Auger, and X-ray photoelectron spectroscopies. Photoluminescence and Raman intensity reductions associated with spectral features of GaSe are shown to coincide with the emergence of signatures emanating from the by-products of the oxidation reaction, namely, Ga2Se3 and amorphous Se. Photoinduced oxidation is initiated over a portion of a flake highlighting the potential for laser based patterning of two-dimensional heterostructures via selective oxidation.

  18. Origins of geothermal gases at Yellowstone

    NASA Astrophysics Data System (ADS)

    Lowenstern, Jacob B.; Bergfeld, Deborah; Evans, William C.; Hunt, Andrew G.

    2015-09-01

    Gas emissions at the Yellowstone Plateau Volcanic Field (YPVF) reflect open-system mixing of gas species originating from diverse rock types, magmas, and crustal fluids, all combined in varying proportions at different thermal areas. Gases are not necessarily in chemical equilibrium with the waters through which they vent, especially in acid sulfate terrain where bubbles stream through stagnant acid water. Gases in adjacent thermal areas often can be differentiated by isotopic and gas ratios, and cannot be tied to one another solely by shallow processes such as boiling-induced fractionation of a parent liquid. Instead, they inherit unique gas ratios (e.g., CH4/He) from the dominant rock reservoirs where they originate, some of which underlie the Quaternary volcanic rocks. Steam/gas ratios (essentially H2O/CO2) of Yellowstone fumaroles correlate with Ar/He and N2/CO2, strongly suggesting that H2O/CO2 is controlled by addition of steam boiled from water rich in atmospheric gases. Moreover, H2O/CO2 varies systematically with geographic location, such that boiling is more enhanced in some areas than others. The ?13C and 3He/CO2 of gases reflect a dominant mantle origin for CO2 in Yellowstone gas. The mantle signature is most evident at Mud Volcano, which hosts gases with the lowest H2O/CO2, lowest CH4 concentrations and highest He isotope ratios (~ 16Ra), consistent with either a young subsurface intrusion or less input of crustal and meteoric gas than any other location at Yellowstone. Across the YPVF, He isotope ratios (3He/4He) inversely vary with He concentrations, and reflect varied amounts of long-stored, radiogenic He added to the magmatic endmember within the crust. Similarly, addition of CH4 from organic-rich sediments is common in the eastern thermal areas at Yellowstone. Overall, Yellowstone gases reflect addition of deep, high-temperature magmatic gas (CO2-rich), lower-temperatures crustal gases (4He- and CH4-bearing), and those gases (N2, Ne, Ar) added principally through boiling of the meteoric-water-derived geothermal liquid found in the upper few kilometers. We also briefly explore the pathways by which Cl, F, and S, move through the crust.

  19. Zevenhoven & Kilpinen FLUE GASES and FUEL GASES 19.6.2001 2-1 Chapter 2 Flue gases and

    E-print Network

    Zevenhoven, Ron

    . By means of a stack of sufficient height these can be dispersed into the atmosphere without much effect-chloroethene, and chemicals such as chlorofluorocarbons (CFCs) and SF6 that contribute to the enhanced greenhouse effect and atmosphere at ground-level. The formation of ground-level ozone from traffic exhaust gases during sunny

  20. The importance of the Montreal Protocol in protecting climate.

    PubMed

    Velders, Guus J M; Andersen, Stephen O; Daniel, John S; Fahey, David W; McFarland, Mack

    2007-03-20

    The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer is a landmark agreement that has successfully reduced the global production, consumption, and emissions of ozone-depleting substances (ODSs). ODSs are also greenhouse gases that contribute to the radiative forcing of climate change. Using historical ODSs emissions and scenarios of potential emissions, we show that the ODS contribution to radiative forcing most likely would have been much larger if the ODS link to stratospheric ozone depletion had not been recognized in 1974 and followed by a series of regulations. The climate protection already achieved by the Montreal Protocol alone is far larger than the reduction target of the first commitment period of the Kyoto Protocol. Additional climate benefits that are significant compared with the Kyoto Protocol reduction target could be achieved by actions under the Montreal Protocol, by managing the emissions of substitute fluorocarbon gases and/or implementing alternative gases with lower global warming potentials. PMID:17360370

  1. Removing Sulphur Dioxide From Stack Gases

    ERIC Educational Resources Information Center

    Slack, A. V.

    1973-01-01

    Process types, process concepts, claims and counterclaims, cost factors, and the level of developed technology for sulfur dioxide control in stack gases are focused upon and evaluated. Wet and dry processes as well as recovery and throwaway processes are compared. (BL)

  2. Probes of Cold Gases: Collective Modes

    E-print Network

    Lathrop, Daniel P.

    Probes of Cold Gases: Collective Modes Stefan Natu JQI Summer School Monday, July 29, 13 #12;Why do a Collective Mode experiment?? Probe excitations -- phonons, plasmons.. Thermodynamic probe EOS Compressibility Spin susceptibility Monday, July 29, 13 #12;Why do a Collective Mode experiment?? Probe excitations

  3. Elimination of gases and contamination from water

    NASA Technical Reports Server (NTRS)

    Buck, A. P.

    1970-01-01

    Filtration system with membrane type hydrophilic and hydrophobic filters gives absolute filtration with automatic venting of freed gases, and prevents backward transmission of contamination with no bacterial growth through the filters. Filter aids in degassing industrial solutions and in removing oxygen from sea water.

  4. Method and apparatus for demisting gases

    SciTech Connect

    Claes, J.; De B.R.

    1981-02-17

    A method and apparatus are described for demisting gases wherein a stream of gas containing submicron liquid particles is caused to pass through a filter material comprising at least in part a material having a porosity of at least 0.985.

  5. 40 CFR 89.312 - Analytical gases.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... be available for operation: (1) Purified nitrogen (Contamination ? 1 ppm C, ? 1 ppm CO, ? 400 ppm CO2... CO2, ? 0.1 ppm NO) (Oxygen content between 18-21 percent vol.) (c) Calibration and span gases. (1... of the NO content); (v) CO2 and purified nitrogen. (3) The true concentration of a span gas must...

  6. 40 CFR 89.312 - Analytical gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... ppm CO2, ? 0.1 ppm NO) (2) (3) Hydrogen-helium mixture (40 ±2 percent hydrogen, balance helium... ppm CO2, ? 0.1 ppm NO) (Oxygen content between 18-21 percent vol.) (c) Calibration and span gases. (1... of the NO content); (v) CO2 and purified nitrogen. (3) The true concentration of a span gas must...

  7. 40 CFR 89.312 - Analytical gases.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ppm CO2, ? 0.1 ppm NO) (2) (3) Hydrogen-helium mixture (40 ±2 percent hydrogen, balance helium... ppm CO2, ? 0.1 ppm NO) (Oxygen content between 18-21 percent vol.) (c) Calibration and span gases. (1... of the NO content); (v) CO2 and purified nitrogen. (3) The true concentration of a span gas must...

  8. Prediction of friction coefficients for gases

    NASA Technical Reports Server (NTRS)

    Taylor, M. F.

    1969-01-01

    Empirical relations are used for correlating laminar and turbulent friction coefficients for gases, with large variations in the physical properties, flowing through smooth tubes. These relations have been used to correlate friction coefficients for hydrogen, helium, nitrogen, carbon dioxide and air.

  9. Detection of toxic gases using cermet sensors

    NASA Astrophysics Data System (ADS)

    Skubal, Laura R.; Vogt, Michael C.

    2004-12-01

    New technologies are needed for detection and identification of gaseous species in near-real time. Voltammetry, applied to cermet electrochemical cell microsensors, was shown in this study to be promising in its ability to discern and quantify gases. The miniature cermet cells were fabricated from ceramic, metallic, and metal oxide components, and reacted uniquely with gases and mixtures in the atmosphere. Neural net chemometrics algorithms were used to interpret the waveforms to extract information about the presence and concentration of constituent gases. Results to date have shown that these sensors can correctly identify more than thirty electroactive gases while showing a high tolerance for interferents. A single element sensor can determine gas concentrations from the part per million level to the percentage level while arrays provide even better detection and discrimination. This work focuses on four constituents of diesel exhaust: benzene, 1,3-butadiene, acrolein, and acetaldehyde. Voltammetric sensors demonstrated reproducible responses to four concentrations of each constituent spiked into diesel exhaust.

  10. Refractive Indices of Gases at Microwave Frequencies

    ERIC Educational Resources Information Center

    Goodhead, D. T.; And Others

    1976-01-01

    Describes a simple microwave interferometer capable of measuring small phase shifts. Proposes laboratory exercises involving the use of the interferometer in the determination of refractive indices of gases and the analysis of the reflection in a test chamber. (Author/CP)

  11. Unitary transformations in weakly nonideal Bose gases

    NASA Astrophysics Data System (ADS)

    Shi, Q.; Safonov, V. L.; Mino, M.; Yamazaki, H.

    1998-02-01

    We developed a method for constructing nonlinear unitary transformations in many-body systems. It is demonstrated how to eliminate the three-boson interaction terms which describe forbidden processes in one- and two-component Bose gases. The corresponding effective four-boson interaction amplitudes are calculated.

  12. Fullerenes and the Nature of Planetary Gases

    NASA Technical Reports Server (NTRS)

    Becker, Luann; Poreda, Robert J.; Nuth, Joe

    2003-01-01

    Over the past several decades, two issues have dominated the discussion of planetary noble gas patterns: 1) the general resemblance of the noble gas abundances in carbonaceous chondrites to those measured in the Earth s atmosphere and; 2) atmospheric inventories of argon and neon that fall off significantly with increasing distance from the Sun. The recognition of the latter has led to the conclusion that the planetary component is not found on planets. In particular, the inability to explain the missing xenon reservoir, once thought to be sequestered in crustal rocks has been extremely troublesome. Some models have focused on various fractionations of solar wind rather than condensation as the process for the evolution of noble gases in the terrestrial planets. However, these models cannot explain the observed gradient of the gases, nor do they account for the similar Ne/Ar ratios and the dissimilar planetary Ar/Kr ratios. More recent studies have focused on hydrodynamic escape to explain the fractionation of gases, like neon, in the atmosphere and the mantle. Escape theory also seems to explain, in part, the isotopically heavy argon on Mars, however, it does not explain the discrepancies observed for the abundances of argon and neon on Venus and the Earth. This has led to the assumption that some combination of solar wind implantation, absorption and escape are needed to explain the nature of planetary noble gases.

  13. Electron-Atom Collisions in Gases

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2013-01-01

    Electron-atom collisions in gases are an aspect of atomic physics. Three experiments in this field employing a thyratron are described: (i) the Ramsauer-Townsend effect, (ii) the excitation and ionization potentials of xenon and (iii) the ion-electron recombination after interrupting the electric discharge.

  14. Production of quantum-degenerate strontium gases

    NASA Astrophysics Data System (ADS)

    Stellmer, Simon; Grimm, Rudolf; Schreck, Florian

    2013-01-01

    We report on an improved scheme to generate Bose-Einstein condensates (BECs) and degenerate Fermi gases of strontium. This scheme allows us to create quantum gases with higher atom number, a shorter time of the experimental cycle, or deeper quantum degeneracy than before. We create a BEC of 84Sr exceeding 107 atoms, which is a 30-fold improvement over previously reported experiments. We increase the atom number of 86Sr BECs to 2.5×104 (a fivefold improvement) and refine the generation of attractively interacting 88Sr BECs. We present a scheme to generate 84Sr BECs with a cycle time of 2 s. We create deeply degenerate 87Sr Fermi gases with T/TF as low as 0.10(1), where the number of populated nuclear spin states can be set to any value between one and ten. Furthermore, we report on a total of five different double-degenerate Bose-Bose and Bose-Fermi mixtures. These studies prepare an excellent starting point for applications of strontium quantum gases anticipated in the near future.

  15. Coherent terahertz echo of tunnel ionization in gases.

    PubMed

    Karpowicz, N; Zhang, X-C

    2009-03-01

    We study tunnel ionized electron wave packet dynamics during the initial transition from a gas to a plasma by detecting the terahertz radiation emitted in the process. Experimental and theoretical results show that much of the observed radiation is due to coherent buildup of bremsstrahlung released during the first electron-atom collision. Coherent control of the tunnel ionization process combined with ab initio modeling provides a real-time view of the initial stages of the formation of a laser-induced plasma and allows us to fully understand this important source of terahertz radiation. PMID:19392516

  16. Coherent Terahertz Echo of Tunnel Ionization in Gases

    SciTech Connect

    Karpowicz, N.; Zhang, X.-C.

    2009-03-06

    We study tunnel ionized electron wave packet dynamics during the initial transition from a gas to a plasma by detecting the terahertz radiation emitted in the process. Experimental and theoretical results show that much of the observed radiation is due to coherent buildup of bremsstrahlung released during the first electron-atom collision. Coherent control of the tunnel ionization process combined with ab initio modeling provides a real-time view of the initial stages of the formation of a laser-induced plasma and allows us to fully understand this important source of terahertz radiation.

  17. Three toxic gases meet in the mitochondria

    PubMed Central

    Decréau, Richard A.; Collman, James P.

    2015-01-01

    The rationale of the study was two-fold: (i) develop a functional synthetic model of the Cytochrome c oxidase (CcO) active site, (ii) use it as a convenient tool to understand or predict the outcome of the reaction of CcO with ligands (physiologically relevant gases and other ligands). At physiological pH and potential, the model catalyzes the 4-electron reduction of oxygen. This model was immobilized on self-assembled-monolayer (SAM) modified electrode. During catalytic oxygen reduction, electron delivery through SAMs is rate limiting, similar to the situation in CcO. This model contains all three redox-active components in CcO's active site, which are required to minimize the production of partially-reduced-oxygen-species (PROS): Fe-heme (“heme a3”) in a myoglobin-like model fitted with a proximal imidazole ligand, and a distal tris-imidazole Copper (“CuB”) complex, where one imidazole is cross-linked to a phenol (mimicking “Tyr244”). This functional CcO model demonstrates how CcO itself might tolerate the hormone NO (which diffuses through the mitochondria). It is proposed that CuB delivers superoxide to NO bound to Fe-heme forming peroxynitrite, then nitrate that diffuses away. Another toxic gas, H2S, has exceptional biological effects: at ~80 ppm, H2S induces a state similar to hibernation in mice, lowering the animal's temperature and slowing respiration. Using our functional CcO model, we have demonstrated that at the same concentration range H2S can reversibly inhibit catalytic oxygen reduction. Such a reversible catalytic process on the model was also demonstrated with an organic compound, tetrazole (TZ). Following studies showed that TZ reversibly inhibits respiration in isolated mitochondria, and induces deactivation of platelets, a mitochondria-rich key component of blood coagulation. Hence, this program is a rare example illustrating the use of a functional model to understand and predict physiologically important reactions at the active site of CcO. PMID:26347655

  18. Three toxic gases meet in the mitochondria.

    PubMed

    Decréau, Richard A; Collman, James P

    2015-01-01

    The rationale of the study was two-fold: (i) develop a functional synthetic model of the Cytochrome c oxidase (CcO) active site, (ii) use it as a convenient tool to understand or predict the outcome of the reaction of CcO with ligands (physiologically relevant gases and other ligands). At physiological pH and potential, the model catalyzes the 4-electron reduction of oxygen. This model was immobilized on self-assembled-monolayer (SAM) modified electrode. During catalytic oxygen reduction, electron delivery through SAMs is rate limiting, similar to the situation in CcO. This model contains all three redox-active components in CcO's active site, which are required to minimize the production of partially-reduced-oxygen-species (PROS): Fe-heme ("heme a3") in a myoglobin-like model fitted with a proximal imidazole ligand, and a distal tris-imidazole Copper ("CuB") complex, where one imidazole is cross-linked to a phenol (mimicking "Tyr244"). This functional CcO model demonstrates how CcO itself might tolerate the hormone NO (which diffuses through the mitochondria). It is proposed that CuB delivers superoxide to NO bound to Fe-heme forming peroxynitrite, then nitrate that diffuses away. Another toxic gas, H2S, has exceptional biological effects: at ~80 ppm, H2S induces a state similar to hibernation in mice, lowering the animal's temperature and slowing respiration. Using our functional CcO model, we have demonstrated that at the same concentration range H2S can reversibly inhibit catalytic oxygen reduction. Such a reversible catalytic process on the model was also demonstrated with an organic compound, tetrazole (TZ). Following studies showed that TZ reversibly inhibits respiration in isolated mitochondria, and induces deactivation of platelets, a mitochondria-rich key component of blood coagulation. Hence, this program is a rare example illustrating the use of a functional model to understand and predict physiologically important reactions at the active site of CcO. PMID:26347655

  19. June 1998 GPS WORLD 33 Global warming and greenhouse gases are

    E-print Network

    Businger, Steven

    June 1998 GPS WORLD 33 Global warming and greenhouse gases are familiar terms of late, spurred by an interna- tional sense of urgency to comprehend the effect of human activity on the earth's cli- mate in the atmosphere play in the dynamic global climate system is little under- stood yet represents an important

  20. Field emissions of greenhouse gases from contrasting biofuel feedstock production systems under different N fertilization rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management choices (crop type, fertilization rate) could affect agricultural soil emissions of important temperature-forcing greenhouse gases (GHGs) such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Soil GHG emissions were measured in situ over the 2010 growing season at a biofu...

  1. he ability to measure air pollution and other chemically reactive trace gases in the lower

    E-print Network

    Martin, Randall

    T he ability to measure air pollution and other chemically reactive trace gases in the lower atmosphere from satellites has a heritage dating back nearly three decades when the first measure- ments). Since then, numerous satellite-based instruments have provided important measurements from Earth

  2. 49 CFR 229.43 - Exhaust and battery gases.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 2013-10-01 false Exhaust and battery gases. 229.43 Section 229.43...Requirements § 229.43 Exhaust and battery gases. (a) Products of combustion...under usual operating conditions. (b) Battery containers shall be vented and...

  3. 49 CFR 229.43 - Exhaust and battery gases.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 2012-10-01 false Exhaust and battery gases. 229.43 Section 229.43...Requirements § 229.43 Exhaust and battery gases. (a) Products of combustion...under usual operating conditions. (b) Battery containers shall be vented and...

  4. 49 CFR 229.43 - Exhaust and battery gases.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 2014-10-01 false Exhaust and battery gases. 229.43 Section 229.43...Requirements § 229.43 Exhaust and battery gases. (a) Products of combustion...under usual operating conditions. (b) Battery containers shall be vented and...

  5. 49 CFR 229.43 - Exhaust and battery gases.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 false Exhaust and battery gases. 229.43 Section 229.43...Requirements § 229.43 Exhaust and battery gases. (a) Products of combustion...under usual operating conditions. (b) Battery containers shall be vented and...

  6. 49 CFR 229.43 - Exhaust and battery gases.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 2010-10-01 false Exhaust and battery gases. 229.43 Section 229.43...Requirements § 229.43 Exhaust and battery gases. (a) Products of combustion...under usual operating conditions. (b) Battery containers shall be vented and...

  7. Detectability of biosignature gases in the atmospheres of terrestrial exoplanets

    E-print Network

    Messenger, Stephen Joseph

    2013-01-01

    Biosignature gases in the atmosphere of an exoplanet provide a means by which we can deduce the possible existence of life on that planet. As the list of possible biosignature gases is ever growing, the need to determine ...

  8. Method for enhancing microbial utilization rates of gases using perfluorocarbons

    DOEpatents

    Turick, Charles E. (Idaho Falls, ID)

    1997-01-01

    A method of enhancing the bacterial reduction of industrial gases using perfluorocarbons (PFCs) is disclosed. Because perfluorocarbons (PFCs) allow for a much greater solubility of gases than water does, PFCs have the potential to deliver gases in higher concentrations to microorganisms when used as an additive to microbial growth media thereby increasing the rate of the industrial gas conversion to economically viable chemicals and gases.

  9. Method for enhancing microbial utilization rates of gases using perfluorocarbons

    DOEpatents

    Turick, C.E.

    1997-06-10

    A method of enhancing the bacterial reduction of industrial gases using perfluorocarbons (PFCs) is disclosed. Because perfluorocarbons (PFCs) allow for a much greater solubility of gases than water does, PFCs have the potential to deliver gases in higher concentrations to microorganisms when used as an additive to microbial growth media thereby increasing the rate of the industrial gas conversion to economically viable chemicals and gases. 3 figs.

  10. Microwave limb sounder. [measuring trace gases in the upper atmosphere

    NASA Technical Reports Server (NTRS)

    Gustincic, J. J. (inventor)

    1981-01-01

    Trace gases in the upper atmosphere can be measured by comparing spectral noise content of limb soundings with the spectral noise content of cold space. An offset Cassegrain antenna system and tiltable input mirror alternately look out at the limb and up at cold space at an elevation angle of about 22. The mirror can also be tilted to look at a black body calibration target. Reflection from the mirror is directed into a radiometer whose head functions as a diplexer to combine the input radiation and a local ocillator (klystron) beam. The radiometer head is comprised of a Fabry-Perot resonator consisting of two Fabry-Perot cavities spaced a number of half wavelengths apart. Incoming radiation received on one side is reflected and rotated 90 deg in polarization by the resonator so that it will be reflected by an input grid into a mixer, while the klystron beam received on the other side is also reflected and rotated 90 deg, but not without passing some energy to be reflected by the input grid into the mixer.

  11. Thermodynamics of Quantum Gases for the Entire Range of Temperature

    ERIC Educational Resources Information Center

    Biswas, Shyamal; Jana, Debnarayan

    2012-01-01

    We have analytically explored the thermodynamics of free Bose and Fermi gases for the entire range of temperature, and have extended the same for harmonically trapped cases. We have obtained approximate chemical potentials for the quantum gases in closed forms of temperature so that the thermodynamic properties of the quantum gases become…

  12. Biological Removal of Siloxanes from Landfill and Digester Gases

    E-print Network

    Biological Removal of Siloxanes from Landfill and Digester Gases: Opportunities and Challenges S U) presents challenges for using landfill and digester gases as energy fuels because of the formation in landfill and digester gases varies according to the source. Concentrations of up to 140 mg m-3 have been

  13. Measuring the Isotopic Composition of Solar Wind Noble Gases

    E-print Network

    Floss, Christine

    5 Measuring the Isotopic Composition of Solar Wind Noble Gases Alex Meshik, Charles Hohenberg, Olga and processes leading to the variations observed and how the present solar wind noble gases may differ from and breccias, implanted with solar wind noble gases, did provide a needed ground truth, neither by themselves

  14. Learning the Critical Points for Addition in Matematika GASING

    ERIC Educational Resources Information Center

    Siregar, Johannes Hamonangan; Wiyanti, Wiwik; Wakhyuningsih, Nur Safitri; Godjali, Ali

    2014-01-01

    We propose learning Matematika GASING to help students better understand the addition material. Matematika GASING is a way of learning mathematics in an easy, fun and enjoyable fashion. GASING is short for GAmpang, aSyIk, and menyenaNGkan (Bahasa Indonesia for easy, fun and enjoyable). It was originally developed by Prof. Yohanes Surya at the…

  15. Residual Gases in Crystal Growth Systems: Their Origin, Magnitude, and Dependence on the Processing Conditions

    NASA Technical Reports Server (NTRS)

    Palosz, W.

    2003-01-01

    Residual gases present in closed ampoules may affect different crystal growth processes. Their presence may affect techniques requiring low pressures and affect the crystal quality in different ways. For that reason a good understanding and control of formation of residual gases may be important for an optimum design and meaningful interpretation of crystal growth experiments. Our extensive experimental and theoretical study includes degassing of silica glass and generation of gases from various source materials. Different materials processing conditions, like outgassing under vacuum, annealing in hydrogen, resublimation, different material preparation procedures, multiple annealings, different processing times, and others were applied and their effect on the amount and composition of gas were analyzed. The experimental results were interpreted based on theoretical calculations on diffusion in silica glass and source materials and thermochemistry of the system. Procedures for a reduction of the amount of gas are also discussed.

  16. A Ni-Doped Carbon Nanotube Sensor for Detecting Oil-Dissolved Gases in Transformers

    PubMed Central

    Lu, Jia; Zhang, Xiaoxing; Wu, Xiaoqing; Dai, Ziqiang; Zhang, Jinbin

    2015-01-01

    C2H2, C2H4, and C2H6 are important oil-dissolved gases in power transformers. Detection of the composition and content of oil-dissolved gases in transformers is very significant in the diagnosis and assessment of the state of transformer operations. The commonly used oil-gas analysis methods have many disadvantages, so this paper proposes a Ni-doped carbon nanotube (Ni-CNT) gas sensor to effectively detect oil-dissolved gases in a transformer. The gas-sensing properties of the sensor to C2H2, C2H4, and C2H6 were studied using the test device. Based on the density functional theory (DFT) the adsorption behaviors of the three gases on intrinsic carbon nanotubes (CNTs) and Ni-CNTs were calculated. The adsorption energy, charge transfer, and molecular frontier orbital of the adsorption system were also analyzed. Results showed that the sensitivity of the CNT sensor to the three kinds of gases was in the following order: C2H2 > C2H4 > C2H6. Moreover, the doped Ni improved the sensor response, and the sensor response and gas concentration have a good linear relationship. PMID:26066989

  17. A Ni-Doped Carbon Nanotube Sensor for Detecting Oil-Dissolved Gases in Transformers.

    PubMed

    Lu, Jia; Zhang, Xiaoxing; Wu, Xiaoqing; Dai, Ziqiang; Zhang, Jinbin

    2015-01-01

    C2H2, C2H4, and C2H6 are important oil-dissolved gases in power transformers. Detection of the composition and content of oil-dissolved gases in transformers is very significant in the diagnosis and assessment of the state of transformer operations. The commonly used oil-gas analysis methods have many disadvantages, so this paper proposes a Ni-doped carbon nanotube (Ni-CNT) gas sensor to effectively detect oil-dissolved gases in a transformer. The gas-sensing properties of the sensor to C2H2, C2H4, and C2H6 were studied using the test device. Based on the density functional theory (DFT) the adsorption behaviors of the three gases on intrinsic carbon nanotubes (CNTs) and Ni-CNTs were calculated. The adsorption energy, charge transfer, and molecular frontier orbital of the adsorption system were also analyzed. Results showed that the sensitivity of the CNT sensor to the three kinds of gases was in the following order: C2H2 > C2H4 > C2H6. Moreover, the doped Ni improved the sensor response, and the sensor response and gas concentration have a good linear relationship. PMID:26066989

  18. What Can Ultracold Fermi Gases Teach Us About High Tc Superconductors and Vice Versa?

    SciTech Connect

    Levin, Kathryn

    2007-01-10

    Studies of superfluidity in ultracold trapped Fermi gases are attracting physicists from a wide range of sub-disciplines including nuclear, condensed matter and particle physics. The excitement in the field is due, in large part, to the remarkable tuneability of these Fermi gases. One can tune the attractive interaction strength continuously from weak to strong (thereby effecting a transition from a BCS to Bose Einstein condensed (BEC) superfluid). One can introduce polarization into the gases at will, which may lead to long-sought-after, but not yet confirmed, exotic superfluid phases. In this talk we discuss the relevance of the cold Fermi gases to other physics subdisciplines. We then summarize how BCS-BEC crossover in the ultracold gases connects with a particularly important topic in condensed matter: high temperature superconductivity. We emphasize some striking similarities relating to the very unusual normal or 'pseudogap' phase of each of the two systems. In the process we give a summary of some of the latest exciting experimental developments in the two fields.

  19. Mobile MAX-DOAS observations of tropospheric trace gases

    NASA Astrophysics Data System (ADS)

    Wagner, T.; Ibrahim, O.; Shaiganfar, R.; Platt, U.

    2009-11-01

    From Multi-Axis- (MAX-) DOAS observations information on tropospheric trace gases close to the surface and up to the free troposphere can be obtained. Usually MAX-DOAS observations are performed at fixed locations, which allows to retrieve the diurnal variation of tropospheric species at that location. Alternatively, MAX-DOAS observations can also be made on mobile platforms like cars, ships or aircrafts. Then, in addition to the vertical (and temporal) distribution, also the horizontal variation of tropospheric trace gases can be measured. Such information is important for the quantitative comparison with model simulations, study of transport processes, and for the validation of tropospheric trace gas products from satellite observations. However, for MAX-DOAS observations from mobile platforms, the standard analysis techniques for MAX-DOAS observations can usually not be applied, because the probed airmasses can change rapidly between successive measurements. In this study we introduce a new technique which overcomes these problems and allows the exploitation of the full information content of mobile MAX-DOAS observations. Our method can also be applied to MAX-DOAS observations made at fixed locations in order to improve the accuracy especially in cases of strong winds. We apply the new technique to MAX-DOAS observations made during an automobile trip from Brussels to Heidelberg.

  20. Mobile MAX-DOAS observations of tropospheric trace gases

    NASA Astrophysics Data System (ADS)

    Wagner, T.; Ibrahim, O.; Shaiganfar, R.; Platt, U.

    2010-02-01

    From Multi-Axis- (MAX-) DOAS observations, information on tropospheric trace gases close to the surface and up to the free troposphere can be obtained. Usually MAX-DOAS observations are performed at fixed locations, which allows to retrieve the diurnal variation of tropospheric species at that location. Alternatively, MAX-DOAS observations can also be made on mobile platforms like cars, ships or aircrafts. Then, in addition to the vertical (and temporal) distribution, also the horizontal variation of tropospheric trace gases can be measured. Such information is important for the quantitative comparison with model simulations, study of transport processes, and for the validation of tropospheric trace gas products from satellite observations. However, for MAX-DOAS observations from mobile platforms, the standard analysis techniques for MAX-DOAS observations can usually not be applied, because the probed airmasses can change rapidly between successive measurements. In this study we introduce a new technique which overcomes these problems and allows the exploitation of the full information content of mobile MAX-DOAS observations. Our method can also be applied to MAX-DOAS observations made at fixed locations in order to improve the accuracy especially in cases of strong winds. We apply the new technique to MAX-DOAS observations made during an automobile trip from Brussels to Heidelberg.

  1. Transonic flows of dense gases over finite wings

    NASA Astrophysics Data System (ADS)

    Cinnella, P.

    2008-04-01

    Transonic inviscid flows of dense gases of the Bethe-Zel'dovich-Thompson (BZT) type over finite wings are numerically investigated. BZT gases are fluids of the retrograde type (i.e., that superheat when expanded), which exhibit a region of negative values of the fundamental derivative of gas dynamics ?. As a consequence, they display, in the transonic and supersonic regime, nonclassical gas dynamic behaviors, such as rarefaction shock waves and mixed shock/fan waves. The peculiar properties of BZT fluids have received increased interest in recent years because of their possible application in energy-conversion cycles. The present research aims at providing insight about the transonic aerodynamics of BZT fluids past finite wings, roughly representative of isolated turbine blades with infinite tip leakage. This represents an important step toward the design of advanced turbine blades by using organic working fluids. An investigation of the flow patterns and aerodynamic performance for several choices of the upstream thermodynamic conditions is provided, and the advantages of using BZT working fluids instead of classical ones are discussed.

  2. Solubilities of nitrogen and noble gases in basalt melt

    NASA Technical Reports Server (NTRS)

    Miyazaki, A.; Hiyagon, H.; Sugiura, N.

    1994-01-01

    Nitrogen and noble gases are important tracers in geochemistry and chosmochemistry. Compared to noble gases, however, physicochemical properties of nitrogen, such as solubility in melt or melt/silicate partition, are not well known. Solubility of nitrogen in basalt melt depends on redox condition of the atmosphere. For example, solubility of nitrogen in E chondrite melt under reducing conditions is as high as 2 mol percent at 1500 C, suggesting that nitrogen is chemically dissolved in silicate melts, i.e., being dissolved as free anions or replacing oxygen sites in silicate network. However, the solubility and the dissolution mechanism of nitrogen under oxidizing conditions are not well investigated. To obtain nitrogen solubility in silicate melts under various redox conditions and to understand its mechanism, we are conducting experiments by using (15)N(15)N-labeled nitrogen gas. This makes it easy to distinguish dissolved nitrogen from later contamination of atmospheric nitrogen, and hence enables us to measure the nitrogen solubility accurately. As a preliminary experiment, we have measured solubility of nitrogen in basalt melt under the atmospheric oxygen pressure.

  3. Degenerate quantum gases with spin-orbit coupling: a review.

    PubMed

    Zhai, Hui

    2015-02-01

    This review focuses on recent developments in synthetic spin-orbit (SO) coupling in ultracold atomic gases. Two types of SO coupling are discussed. One is Raman process induced coupling between spin and motion along one of the spatial directions and the other is Rashba SO coupling. We emphasize their common features in both single-particle and two-body physics and the consequences of both in many-body physics. For instance, single particle ground state degeneracy leads to novel features of superfluidity and a richer phase diagram; increased low-energy density-of-state enhances interaction effects; the absence of Galilean invariance and spin-momentum locking gives rise to intriguing behaviours of superfluid critical velocity and novel quantum dynamics; and the mixing of two-body singlet and triplet states yields a novel fermion pairing structure and topological superfluids. With these examples, we show that investigating SO coupling in cold atom systems can, enrich our understanding of basic phenomena such as superfluidity, provide a good platform for simulating condensed matter states such as topological superfluids and more importantly, result in novel quantum systems such as SO coupled unitary Fermi gas and high spin quantum gases. Finally we also point out major challenges and some possible future directions. PMID:25640665

  4. The state of greenhouse gases in the atmosphere using global observations through 2012

    NASA Astrophysics Data System (ADS)

    Tarasova, Oksana; Koide, Hiroshi; Dlugokencky, Edward; Montzka, Stephen A.; Butler, James H.

    2014-05-01

    The Global Atmosphere Watch (GAW) Programme of the World Meteorological Organization (WMO) provides a framework for global observations and assessment of the state and development of atmospheric composition, including greenhouse gases. It puts stringent requirements on the quality of the observations. These requirements are reviewed by the greenhouse gas science and measurement community at biennial WMO/IAEA Meetings on Carbon Dioxide, Other Greenhouse Gases, and Related Tracer Measurement Techniques. The 17th meeting was held in Beijing, China, on 10 - 14 June 2013 (http://ggmt-2013.cma.gov.cn/dct/page/1). Results of global analysis of the observational data are reported annually in the WMO/GAW Annual Greenhouse Gas Bulletin. Bulletin No. 9 represents an update of the results for the year 2012 (extended version is available at http://www.wmo.int/pages/prog/arep/gaw/ghg/ghg9-en-online.html). The cover story of this bulletin presents the attribution of methane sources in the context of the renewed growth of the global average methane mole fraction in 2007. The bulletin is prepared by the WMO/GAW Scientific Advisory Group for Greenhouse Gases (http://www.wmo.int/pages/prog/www/CBS/Lists_WorkGroups/CAS/opag-epac/gaw%20sag%20ghg) in collaboration with the World Data Center for Greenhouse Gases. Observations used for global analysis are collected at more than 100 marine and terrestrial sites worldwide for CO2 and CH4 and at a smaller number of sites for other greenhouse gases. Globally averaged dry-air mole fractions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) derived from this network reached new highs in 2012, with CO2 at 393.1±0.1 ppm, CH4 at 1819±1 ppb and N2O at 325.1±0.1 ppb. These values constitute 141%, 260% and 120% of pre-industrial (before 1750) levels, respectively. The increase of the annual mean CO2 mole fraction from 2011 to 2012 amounted to 2.2 ppm, which is greater than the average growth rate for the 1990s (~1.5 ppm yr-1) and for the past decade (~2.0 ppm yr-1). The globally averaged CH4 mole fraction increased by 6 ppb from 2011 to 2012. The growth rate of CH4 decreased from ~13 ppb yr-1 during the early 1980s to near zero during 1999-2006. Since 2007, atmospheric CH4 has been increasing again, averaging ~5 ppb yr-1. The growth rate of N2O in 2012 was 0.9 ppb yr-1, which is greater than the average growth rate over the last 10 years (0.75 ppb yr-1). The NOAA Annual Greenhouse Gas Index (AGGI) has been defined as the ratio of total radiative forcing due to long-lived greenhouse gases for any year for which adequate global measurements exist to that which was present in 1990. The AGGI in 2012 was 1.32 (corresponding to 2.87 W m-2 of global radiative forcing, relative to 1750, of all long-lived greenhouse gases). The AGGI indicates an increase in radiative forcing by all long-lived greenhouse gases of 32% since 1990 and of 1.2% from 2011 to 2012, while the radiative forcing by all long-lived greenhouse gases in 2012 corresponded to a CO2-equivalent mole fraction of 475.6 ppm (http://www.esrl.noaa.gov/gmd/aggi).

  5. In Situ Imaging of Atomic Quantum Gases

    NASA Astrophysics Data System (ADS)

    Hung, Chen-Lung; Chin, Cheng

    2015-09-01

    One exciting progress in recent cold atom experiments is the development of high resolution, in situ imaging techniques for atomic quantum gases.1-3 These new powerful tools provide detailed information on the distribution of atoms in a trap with resolution approaching the level of single atom and even single lattice site, and complement the welldeveloped time-of-flight method that probes the system in momentum space. In a condensed matter analogy, this technique is equivalent to locating electrons of a material in a snap shot. In situ imaging has offered a new powerful tool to study atomic gases and inspired many new research directions and ideas. In this chapter, we will describe the experimental setup of in situ absorption imaging, observables that can be extracted from the images, and new physics that can be explored with this technique.

  6. Anesthetic gases and occupationally exposed workers.

    PubMed

    Casale, Teodorico; Caciari, Tiziana; Rosati, Maria Valeria; Gioffrè, Pier Agostino; Schifano, Maria Pia; Capozzella, Assunta; Pimpinella, Benedetta; Tomei, Gianfranco; Tomei, Francesco

    2014-01-01

    The aim of this study is to estimate whether the occupational exposure to low dose anesthetic gases could cause alterations of blood parameters in health care workers. 119 exposed subjects and 184 not exposed controls were included in the study. Each worker underwent the complete blood count test (CBC), proteinaemia, leukocyte count, serum lipids, liver and kidney blood markers. The liver blood markers show statistically significant differences in health care workers compared with controls (p<0.05), a statistically significant decrease in neutrophils and an increase of lymphocytes in health care workers compared with controls (p<0.05). The prevalence of values outside the range for GPT, GGT, total bilirubin, lymphocytes and neutrophils was statistically significant in health care workers compared with controls (p<0.05). The results suggest that occupational exposure to low dose anesthetic gases could influence some haematochemical hepatic and hematopoietic parameters in exposed health care workers. PMID:24374387

  7. Study of electron transport in hydrocarbon gases

    NASA Astrophysics Data System (ADS)

    Hasegawa, H.; Date, H.

    2015-04-01

    The drift velocity and the effective ionization coefficient of electrons in the organic gases, C2H2, C2H4, C2H6, CH3OH, C2H5OH, C6H6, and C6H5CH3, have been measured over relatively wide ranges of density-reduced electric fields (E/N) at room temperature (around 300 K). The drift velocity was measured, based on the arrival-time spectra of electrons by using a double-shutter drift tube over the E/N range from 300 to 2800 Td, and the effective ionization coefficient (? - ?) was determined by the steady-state Townsend method from 150 to 3000 Td. Whenever possible, these parameters were compared with those available in the literature. It has been shown that the swarm parameters for these gases have specific tendencies, depending on their molecular configurations.

  8. Scale-invariant nonlinear optics in gases

    E-print Network

    Heyl, C M; Miranda, M; Louisy, M; Kovacs, K; Tosa, V; Balogh, E; Varjú, K; L'Huillier, A; Couairon, A; Arnold, C L

    2015-01-01

    Nonlinear optical methods are becoming ubiquitous in many areas of modern photonics. They are, however, often limited to a certain range of input parameters, such as pulse energy and average power, since restrictions arise from, for example, parasitic nonlinear effects, damage problems and geometrical considerations. Here, we show that many nonlinear optics phenomena in gaseous media are scale-invariant if spatial coordinates, gas density and laser pulse energy are scaled appropriately. We develop a general scaling model for (3+1)-dimensional wave equations, demonstrating the invariant scaling of nonlinear pulse propagation in gases. Our model is numerically applied to high-order harmonic generation and filamentation as well as experimentally verified using the example of pulse post-compression via filamentation. Our results provide a simple recipe for up-or downscaling of nonlinear processes in gases with numerous applications in many areas of science.

  9. 1988 Pilot Institute on Global Change on trace gases and the biosphere

    SciTech Connect

    Eddy, J.A.; Moore, B. III

    1998-07-01

    This proposal seeks multi-agency funding to conduct an international, multidisciplinary 1988 Pilot Institute on Global Change to take place from August 7 through 21, 1988, on the topic: Trace Gases and the Biosphere. The institute, to be held in Snowmass, Colorado, is envisioned as a pilot version of a continuing series of institutes on Global Change (IGC). This proposal seeks support for the 1988 pilot institute only. The concept and structure for the continuing series, and the definition of the 1988 pilot institute, were developed at an intensive and multidisciplinary Summer Institute Planning Meeting in Boulder, Colorado, on August 24--25, 1987. The theme for the 1988 PIGC, Trace Gases and the Biosphere, will focus a concerted, high-level multidisciplinary effort on a scientific problem central to the Global Change Program. Dramatic year-to-year increases in the global concentrations of radiatively-active trace gases such as methane and carbon dioxide are now well documented. The predicted climatic effects of these changes lend special urgency to efforts to study the biospheric sources and sinks of these gases and to clarify their interactions and role in the geosphere-biosphere system.

  10. ENERGY RELAXATION OF HELIUM ATOMS IN ASTROPHYSICAL GASES

    SciTech Connect

    Lewkow, N. R.; Kharchenko, V.; Zhang, P.

    2012-09-01

    We report accurate parameters describing energy relaxation of He atoms in atomic gases, important for astrophysics and atmospheric science. Collisional energy exchange between helium atoms and atomic constituents of the interstellar gas, heliosphere, and upper planetary atmosphere has been investigated. Energy transfer rates, number of collisions required for thermalization, energy distributions of recoil atoms, and other major parameters of energy relaxation for fast He atoms in thermal H, He, and O gases have been computed in a broad interval of energies from 10 meV to 10 keV. This energy interval is important for astrophysical applications involving the energy deposition of energetic atoms and ions into atmospheres of planets and exoplanets, atmospheric evolution, and analysis of non-equilibrium processes in the interstellar gas and heliosphere. Angular- and energy-dependent cross sections, required for an accurate description of the momentum-energy transfer, are obtained using ab initio interaction potentials and quantum mechanical calculations for scattering processes. Calculation methods used include partial wave analysis for collisional energies below 2 keV and the eikonal approximation at energies higher than 100 eV, keeping a significant energy region of overlap, 0.1-2 keV, between these two methods for their mutual verification. The partial wave method and the eikonal approximation excellently match results obtained with each other as well as experimental data, providing reliable cross sections in the astrophysically important interval of energies from 10 meV to 10 keV. Analytical formulae, interpolating obtained energy- and angular-dependent cross sections, are presented to simplify potential applications of the reported database. Thermalization of fast He atoms in the interstellar gas and energy relaxation of hot He and O atoms in the upper atmosphere of Mars are considered as illustrative examples of potential applications of the new database.

  11. Method for introduction of gases into microspheres

    DOEpatents

    Hendricks, Charles D. (Livermore, CA); Koo, Jackson C. (San Ramon, CA); Rosencwaig, Allan (Danville, CA)

    1981-01-01

    A method for producing small hollow glass spheres filled with a gas by introduction of the gas during formation of the hollow glass spheres. Hollow glass microspheres having a diameter up to about 500.mu. with both thin walls (0.5 to 4.mu.) and thick walls (5 to 20.mu.) that contain various fill gases, such as Ar, Kr, Xe, Br, DT, H.sub.2, D.sub.2, He, N.sub.2, Ne, CO.sub.2, etc. in the interior thereof, can be produced by the diffusion of the fill gas or gases into the microsphere during the formation thereof from a liquid droplet of glass-forming solution. This is accomplished by filling at least a portion of the multiple-zone drop-furnace used in producing hollow microspheres with the gas or gases of interest, and then taking advantage of the high rate of gaseous diffusion of the fill gas through the wall of the gel membrane before it transforms into a glass microsphere as it is processed in the multiple-zone furnace. Almost any gas can be introduced into the inner cavity of a glass microsphere by this method during the formation of the microsphere provided that the gas is diffused into the gel membrane or microsphere prior to its transformation into glass. The process of this invention provides a significant savings of time and related expense of filling glass microspheres with various gases. For example, the time for filling a glass microballoon with 1 atmosphere of DT is reduced from about two hours to a few seconds.

  12. Noble Gases in the Chelyabinsk Meteorites

    NASA Technical Reports Server (NTRS)

    Haba, Makiko K.; Sumino, Hirochika; Nagao, Keisuke; Mikouchi, Takashi; Komatsu, Mutsumi; Zolensky, Michael E.

    2014-01-01

    The Chelyabinsk meteorite fell in Russia on February 15, 2013 and was classified as LL5 chondrite. The diameter before it entered the atmosphere has been estimated to be about 20 m [1]. Up to now, numerous fragments weighing much greater than 100 kg in total have been collected. In this study, all noble gases were measured for 13 fragments to investigate the exposure history of the Chelyabinsk meteorite and the thermal history of its parent asteroid.

  13. Toxicity of Pyrolysis Gases from Elastomers

    NASA Technical Reports Server (NTRS)

    Hilado, Carlos J.; Kosola, Kay L.; Solis, Alida N.; Kourtides, Demetrius A.; Parker, John A.

    1977-01-01

    The toxicity of the pyrolysis gases from six elastomers was investigated. The elastomers were polyisoprene (natural rubber), styrene-butadiene rubber (SBR), ethylene propylene diene terpolymer (EPDM), acrylonitrile rubber, chlorosulfonated polyethylene rubber, and polychloroprene. The rising temperature and fixed temperature programs produced exactly the same rank order of materials based on time to death. Acryltonitrile rubber exhibited the greatest toxicity under these test conditions; carbon monoxide was not found in sufficient concentrations to be the primary cause of death.

  14. Concentrating Trace Gases at Low Pressures

    NASA Technical Reports Server (NTRS)

    Vedder, James F.; O'Hara, Dean; Vo, Tuyen

    1987-01-01

    Open adsorption tube enables measurement of gases at parts-per-trillion-by-volume concentrations. Traps trace materials in flowing gas. Variety of configurations possible; tube consists of single long coil instead of several short ones, and tube is made of materials other than stainless steel. Partial immersion of coil in cryogen results in 100 percent trapping rather than typical 85 percent for total immersion.

  15. Scanning electron microscopy of cold gases

    E-print Network

    Santra, Bodhaditya

    2015-01-01

    Ultracold quantum gases offer unique possibilities to study interacting many-body quantum systems. Probing and manipulating such systems with ever increasing degree of control requires novel experimental techniques. Scanning electron microscopy is a high resolution technique which can be used for in situ imaging, single site addressing in optical lattices and precision density engineering. Here, we review recent advances and achievements obtained with this technique and discuss future perspectives.

  16. Improved Cloud-Radiation Parameterization for GCMs through the ARM Program. Final Progress Report

    SciTech Connect

    Kiehl, J. T.

    2004-03-31

    Climate sensitivity is an important determinant of climate change. In terms of global climate response, climate sensitivity determines the magnitude of climate change due to radiative forcings by greenhouse gases. The IPCC reports have pointed out that much of the uncertainty in climate projections can be attributed to the disparity in modeled climate sensitivity. Thus, it is imperative to understand the magnitude of climate sensitivity for a given model, and an understanding of what role physical processes play in determining the models particular climate sensitivity.

  17. Treatment of flue gas containing noxious gases

    SciTech Connect

    Dvirka, M.; Psihos, G.J.; Cosulich, J.J.

    1987-07-21

    A method is described of reducing the noxious gases such as chlorides including hydrogen chloride and chlorine from the flue gases derived from the incineration of solid waste materials in a furnace with a combustion chamber and a combustion zone to substantially reduce the formation of dioxins for a cleaner effluent gas to the atmosphere, comprising: introducing sodium bicarbonate into the flue gas of a furnace incinerating the waste materials, positioning introduction of sodium bicarbonate for at least one location along the path of the flue gas at a temperature below about 1564/sup 0/F but not below about 518/sup 0/F, heating the sodium bicarbonate in the flue gas for a time sufficient to drive off the water and carbon dioxide from the sodium bicarbonate, forming sodium carbonate particle during the heating of the sodium bicarbonate, the sodium carbonate having a higher porosity to produce a greater reaction area on the surface of the particles, contacting the porous sodium carbonate with chlorides in the flue gases for a sufficient time and temperature to react and produce sodium chloride and prevent their formation of dioxins; and separating the sodium chloride from the flue gas to produce a cleaner gas for exit to the atmosphere.

  18. 49 CFR 174.204 - Tank car delivery of gases, including cryogenic liquids.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Tank car delivery of gases, including cryogenic...Gases) Materials § 174.204 Tank car delivery of gases, including cryogenic liquids. (a) A tank car containing Class 2 (gases)...

  19. 49 CFR 174.204 - Tank car delivery of gases, including cryogenic liquids.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Tank car delivery of gases, including cryogenic...Gases) Materials § 174.204 Tank car delivery of gases, including cryogenic liquids. (a) A tank car containing Class 2 (gases)...

  20. 49 CFR 174.204 - Tank car delivery of gases, including cryogenic liquids.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Tank car delivery of gases, including cryogenic...Gases) Materials § 174.204 Tank car delivery of gases, including cryogenic liquids. (a) A tank car containing Class 2 (gases)...

  1. 49 CFR 174.204 - Tank car delivery of gases, including cryogenic liquids.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Tank car delivery of gases, including cryogenic...Gases) Materials § 174.204 Tank car delivery of gases, including cryogenic liquids. (a) A tank car containing Class 2 (gases)...

  2. 49 CFR 174.204 - Tank car delivery of gases, including cryogenic liquids.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Tank car delivery of gases, including cryogenic...Gases) Materials § 174.204 Tank car delivery of gases, including cryogenic liquids. (a) A tank car containing Class 2 (gases)...

  3. Spectral investigations of photoionized plasmas induced in atomic and molecular gases using nanosecond extreme ultraviolet (EUV) pulses

    SciTech Connect

    Bartnik, A.; Fiedorowicz, H.; Wachulak, P.

    2014-07-15

    In this paper, results of spectral investigations of low temperature photoionized plasmas, created by irradiation of gases with intense pulses of extreme ultraviolet (EUV) radiation from a laser-produced plasma (LPP) source, are presented. The LPP source was based on a double-stream KrXe/He gas-puff target irradiated with 4?ns/0.8?J/10?Hz Nd:YAG laser pulses. The most intense emission from the source spanned a relatively narrow spectral region ????10–12?nm; however, spectrally integrated intensity at longer wavelengths was also significant. The EUV beam was focused on a gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Irradiation of gases resulted in formation of photoionized plasmas emitting radiation in the EUV range. Radiation spectra, measured for plasmas produced in various gases, are dominated by emission lines, originating from single charged ions. Significant differences in spectral intensities and distributions between plasmas created in neon and molecular gases were observed.

  4. Please Talk with Your Grandfather Two topics, one old and bedraggled, one important

    E-print Network

    Hansen, James E.

    -made trace gases might have an important greenhouse effect (until then, only carbon dioxide greenhouse gases into the air would have the opposite effect ­ a modern day ice age. James Hansen is currently among scientists who believe that carbon dioxide emissions are warming the planet's atmosphere

  5. Emissions Of Greenhouse Gases From Rice Agriculture

    SciTech Connect

    M. Aslam K. Khalil

    2009-07-16

    This project produced detailed data on the processes that affect methane and nitrous oxide emissions from rice agriculture and their inter-relationships. It defines the shifting roles and potential future of these gases in causing global warming and the benefits and tradeoffs of reducing emissions. The major results include: 1). Mechanisms and Processes Leading to Methane Emissions are Delineated. Our experiments have tested the standard model of methane emissions from rice fields and found new results on the processes that control the flux. A mathematical mass balance model was used to unravel the production, oxidation and transport of methane from rice. The results suggested that when large amounts of organic matter are applied, the additional flux that is observed is due to both greater production and reduced oxidation of methane. 2). Methane Emissions From China Have Been Decreasing Over the Last Two Decades. We have calculated that methane emissions from rice fields have been falling in recent decades. This decrease is particularly large in China. While some of this is due to reduced area of rice agriculture, the bigger effect is from the reduction in the emission factor which is the annual amount of methane emitted per hectare of rice. The two most important changes that cause this decreasing emission from China are the reduced use of organic amendments which have been replaced by commercial nitrogen fertilizers, and the increased practice of intermittent flooding as greater demands are placed on water resources. 3). Global Methane Emissions Have Been Constant For More Than 20 Years. While the concentrations of methane in the atmosphere have been leveling off in recent years, our studies show that this is caused by a near constant total global source of methane for the last 20 years or more. This is probably because as some anthropogenic sources have increased, others, such as the rice agriculture source, have fallen. Changes in natural emissions appear small. 4). Nitrous Oxide Emissions From Rice Fields Increase as Methane Emissions Drop. Inundated conditions favor anaerobic methane production with high emission rates and de-nitrification resulting in modest nitrous oxide emissions. Under drier conditions such as intermittent flooding, methane emissions fall and nitrous oxide emissions increase. Increased nitrogen fertilizer use increases nitrous oxide emissions and is usually accompanied by reduced organic matter applications which decreases methane emissions. These mechanisms cause a generally inverse relationship between methane and nitrous oxide emissions. Reduction of methane from rice agriculture to control global warming comes with tradeoffs with increased nitrous oxide emissions. 5). High Spatial Resolution Maps of Emissions Produced. Maps of methane and nitrous oxide emissions at a resolution of 5 min × 5 min have been produced based on the composite results of this research. These maps are necessary for both scientific and policy uses.

  6. Radio-Frequency Spectroscopy of strongly interacting Fermi gases

    NASA Astrophysics Data System (ADS)

    Schirotzek, Andre; Wu, Cheng-Hsun; Sommer, Ariel; Zwierlein, Martin

    2009-05-01

    Strongly interacting Fermi gases exhibit a rich phase diagram in the BEC-BCS crossover. In recent experiments we have used radio frequency spectroscopy to probe two physically very different regimes: 1.) We have observed Spin-Polarons in a highly imbalanced Fermi mixture. A single spin down atom immersed in a spin up Fermi sea dresses itself with a cloud of majority atoms, thus forming a Spin-Polaron. rf spectroscopy can directly reveal the polaron and allows for an experimental measure of the quasiparticle residue Z and the chemical potential ? of this Fermi liquid. At a critical interaction strength, the transition to two-particle molecular binding is observed. 2.) rf spectroscopy of quasiparticles in a polarized superfluid allowed us to determine the superfluid gap ? and has demonstrated the importance of the Hartree energy U in rf spectra [1]. [1] Andre Schirotzek, Yong-il Shin, Christian H. Schunck and Wolfgang Ketterle, Phys. Rev. Lett. 101, 140403 (2008)

  7. Spin-imbalanced quasi-two-dimensional Fermi gases.

    PubMed

    Ong, W; Cheng, Chingyun; Arakelyan, I; Thomas, J E

    2015-03-20

    We measure the density profiles for a Fermi gas of (6)Li containing N(1) spin-up atoms and N(2) spin-down atoms, confined in a quasi-two-dimensional geometry. The spatial profiles are measured as a function of spin imbalance N(2)/N(1) and interaction strength, which is controlled by means of a collisional (Feshbach) resonance. The measured cloud radii and central densities are in disagreement with mean-field Bardeen-Cooper-Schrieffer theory for a true two-dimensional system. We find that the data for normal-fluid mixtures are reasonably well fit by a simple two-dimensional polaron model of the free energy. Not predicted by the model is a phase transition to a spin-balanced central core, which is observed above a critical value of N(2)/N(1). Our observations provide important benchmarks for predictions of the phase structure of quasi-two-dimensional Fermi gases. PMID:25839246

  8. Greenhouse gases accounting and reporting for waste management - A South African perspective

    SciTech Connect

    Friedrich, Elena; Trois, Cristina

    2010-11-15

    This paper investigates how greenhouse gases are accounted and reported in the waste sector in South Africa. Developing countries (including South Africa) do not have binding emission reduction targets, but many of them publish different greenhouse gas emissions data which have been accounted and reported in different ways. Results show that for South Africa, inventories at national and municipal level are the most important tools in the process of accounting and reporting greenhouse gases from waste. For the development of these inventories international initiatives were important catalysts at national and municipal levels, and assisted in developing local expertise, resulting in increased output quality. However, discrepancies in the methodology used to account greenhouse gases from waste between inventories still remain a concern. This is a challenging issue for developing countries, especially African ones, since higher accuracy methods are more data intensive. Analysis of the South African inventories shows that results from the recent inventories can not be compared with older ones due to the use of different accounting methodologies. More recently the use of Clean Development Mechanism (CDM) procedures in Africa, geared towards direct measurements of greenhouse gases from landfill sites, has increased and resulted in an improvement of the quality of greenhouse gas inventories at municipal level.

  9. Photosensitive dopants for liquid noble gases

    DOEpatents

    Anderson, David F. (Wheaton, IL)

    1988-01-01

    In an ionization type detector for high energy radiation wherein the energy of incident radiation is absorbed through the ionization of a liquid noble gas and resulting free charge is collected to form a signal indicative of the energy of the incident radiation, an improvement comprising doping the liquid noble gas with photosensitive molecules to convert scintillation light due to recombination of ions, to additional free charge.

  10. Anesthetic gases and global warming: Potentials, prevention and future of anesthesia

    PubMed Central

    Gadani, Hina; Vyas, Arun

    2011-01-01

    Global warming refers to an average increase in the earth?s temperature, which in turn causes changes in climate. A warmer earth may lead to changes in rainfall patterns, a rise in sea level, and a wide range of impacts on plants, wildlife, and humans. Greenhouse gases make the earth warmer by trapping energy inside the atmosphere. Greenhouse gases are any gas that absorbs infrared radiation in the atmosphere and include: water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), halogenated fluorocarbons (HCFCs), ozone (O3), perfluorinated carbons (PFCs), and hydrofluorocarbons (HFCs). Hazardous chemicals enter the air we breathe as a result of dozens of activities carried out during a typical day at a healthcare facility like processing lab samples, burning fossil fuels etc. We sometimes forget that anesthetic agents are also greenhouse gases (GHGs). Anesthetic agents used today are volatile halogenated ethers and the common carrier gas nitrous oxide known to be aggressive GHGs. With less than 5% of the total delivered halogenated anesthetic being metabolized by the patient, the vast majority of the anesthetic is routinely vented to the atmosphere through the operating room scavenging system. The global warming potential (GWP) of a halogenated anesthetic is up to 2,000 times greater than CO2. Global warming potentials are used to compare the strength of different GHGs to trap heat in the atmosphere relative to that of CO2. Here we discuss about the GWP of anesthetic gases, preventive measures to decrease the global warming effects of anesthetic gases and Xenon, a newer anesthetic gas for the future of anesthesia. PMID:25885293

  11. Acute radiation syndrome caused by accidental radiation exposure - therapeutic principles

    PubMed Central

    2011-01-01

    Fortunately radiation accidents are infrequent occurrences, but since they have the potential of large scale events like the nuclear accidents of Chernobyl and Fukushima, preparatory planning of the medical management of radiation accident victims is very important. Radiation accidents can result in different types of radiation exposure for which the diagnostic and therapeutic measures, as well as the outcomes, differ. The clinical course of acute radiation syndrome depends on the absorbed radiation dose and its distribution. Multi-organ-involvement and multi-organ-failure need be taken into account. The most vulnerable organ system to radiation exposure is the hematopoietic system. In addition to hematopoietic syndrome, radiation induced damage to the skin plays an important role in diagnostics and the treatment of radiation accident victims. The most important therapeutic principles with special reference to hematopoietic syndrome and cutaneous radiation syndrome are reviewed. PMID:22114866

  12. Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases, Fiscal Year 2002 Annual Report

    SciTech Connect

    Cushman, R.M.

    2003-08-28

    The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has, since its inception in 1982, enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change, including atmospheric concentrations and atmospheric emissions of carbon dioxide (CO{sub 2}) and other radiatively active gases; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea levels.

  13. Preserving noble gases in a convecting mantle.

    PubMed

    Gonnermann, Helge M; Mukhopadhyay, Sujoy

    2009-05-28

    High (3)He/(4)He ratios sampled at many ocean islands are usually attributed to an essentially undegassed lower-mantle reservoir with high (3)He concentrations. A large and mostly undegassed mantle reservoir is also required to balance the Earth's (40)Ar budget, because only half of the (40)Ar produced from the radioactive decay of (40)K is accounted for by the atmosphere and upper mantle. However, geophysical and geochemical observations suggest slab subduction into the lower mantle, implying that most or all of Earth's mantle should have been processed by partial melting beneath mid-ocean ridges and hotspot volcanoes. This should have left noble gases in both the upper and the lower mantle extensively outgassed, contrary to expectations from (3)He/(4)He ratios and the Earth's (40)Ar budget. Here we suggest a simple solution: recycling and mixing of noble-gas-depleted slabs dilutes the concentrations of noble gases in the mantle, thereby decreasing the rate of mantle degassing and leaving significant amounts of noble gases in the processed mantle. As a result, even when the mass flux across the 660-km seismic discontinuity is equivalent to approximately one lower-mantle mass over the Earth's history, high (3)He contents, high (3)He/(4)He ratios and (40)Ar concentrations high enough to satisfy the (40)Ar mass balance of the Earth can be preserved in the lower mantle. The differences in (3)He/(4)He ratios between mid-ocean-ridge basalts and ocean island basalts, as well as high concentrations of (3)He and (40)Ar in the mantle source of ocean island basalts, can be explained within the framework of different processing rates for the upper and the lower mantle. Hence, to preserve primitive noble gas signatures, we find no need for hidden reservoirs or convective isolation of the lower mantle for any length of time. PMID:19478782

  14. Adsorption of Gases on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Mbaye, Mamadou Thiao

    This research focus in studying the interaction between various classical and quantum gases with novel carbon nanostructures, mainly carbon nanotubes (CNTs). Since their discovery by the Japanese physicist Sumio Iijima [1] carbon nanotubes have, experimentally and theoretically, been subjected to many scientific investigation. Studies of adsorption on CNTs are particularly directed toward their better usage in gas storage, gas separation, catalyst, drug delivery, and water purification. We explore the adsorption of different gases entrapped in a single, double, or multi-bundles of CNTs using computer simulations. The first system we investigate consists of Ar and Kr films adsorbed on zigzag or armchair nanotubes. Our simulations revealed that Kr atoms on intermediate size zigzag NTs undergo two phase transitions: A liquid-vapor (L?V), and liquid-commensurate (L?CS) with a fractional coverage of one Kr atoms adsorbed for every four carbon atoms. For Ar on zigzag and armchair NTs, the only transition observed is a L?V. In the second problem, we explore the adsorption of CO2 molecules in a nanotube bundle and calculate the isosteric heat of adsorption of the entrapped molecules within the groove. We observed that the lower the temperature, the higher the isosteric of adsorption. Last, we investigate the adsorption of hydrogen, Helium, and Neon gases on the groove site of two parallel nanotubes. At low temperature, the transverse motion on the plane perpendicular to the tubes' axis is frozen out and as a consequence, the heat capacity is reduced to 1/2. At high temperature, the atoms gain more degree of freedom and as a consequence the heat capacity is 5/2.

  15. Remote Sensing of Greenhouse Gases and Their Sources and Sinks

    NASA Astrophysics Data System (ADS)

    Butz, Andre; Babenhauserheide, Arne; Bertleff, Marco; Checa-Garcia, Ramiro; Hahne, Philipp; Hase, Frank; Klappenbach, Friedrich; Kostinek, Julian; Aben, Ilse; Hasekamp, Otto; Landgraf, Jochen; Galli, Andre; Basu, Sourish

    2014-06-01

    The man-made emissions of the greenhouse gases carbon dioxide (CO2) and methane (CH4) are considered the main drivers of anthropogenically induced climate change. Major uncertainties persist when it comes to quantifying regional scale surface fluxes of these gases or predicting the evolution of the relevant source/sink processes in a changing climate. Remote sensing of the atmospheric greenhouse gas concentrations from space-borne and ground-based platforms offers the opportunity to significantly advance our knowledge on spatial and temporal scales that are suitable for process attribution and mitigation actions. Overall, the most promising remote-sensing strategy exploits the rotational-vibrational absorption of CO2 and CH4 in sunlight penetrating the Earth's atmosphere. Typically, satellite sounders such as GOSAT (Greenhouse Gases Observing Satellite), OCO-2 (Orbiting Carbon Observatory), and S5P (Sentinel-5 precursor) as well as the ground-based spectrometers of the TCCON (Total Carbon Column Observing Network) cover various CO2, CH4, and O2 absorption bands in the near and shortwave infrared spectral range between 0.75 micron (13400cm-1) and 2.5 micron (4000cm-1). Accuracy of the inferred gas concentrations is contingent on the accuracy of the adopted spectroscopic parameters and spectroscopic models available in these spectral regions. Here, I will report on recent achievements and challenges within our greenhouse-gas remote-sensing activities mainly focusing on the GOSAT observational record. Since its launch in early 2009, the Fourier Transform Spectrometer onboard GOSAT delivers solar absorption spectra with good spectral resolution and high signal-to-noise. It has been shown that the CO2 and CH4 retrievals from these observations can achieve an accuracy on the order of fractions of a percent which makes them suitable for tracking regional scale source/sink processes and their response to climate events. In order to achieve the required accuracy, it is crucial to develop highly accurate radiative-transfer algorithms and to validate the satellite soundings by ground-based observations. I will illustrate some cases where the excellent quality of the absorption spectra collected by GOSAT reveals spectroscopic deficiencies and inconsistencies among the various absorption bands covered. As such, lessons learned from GOSAT can be used as a feedback to the spectroscopy community. Beyond GOSAT, future satellite missions such as S5P or the planned S5 (Sentinel-5, launch ˜2020) will cover spectral ranges which have not yet been spectroscopically optimized for remote-sensing purposes. In that case, simulations and studies based on ground-based observations show that spectroscopic uncertainties constitute a dominant contribution to the error budget of the retrieved gas concentrations. Therefore, further improvements of spectroscopic parameters and line-shape models is of paramount interest for remote sensing of greenhouse gases.

  16. Astrophysical fluid simulations of thermally ideal gases with non-constant adiabatic index: numerical implementation

    NASA Astrophysics Data System (ADS)

    Vaidya, B.; Mignone, A.; Bodo, G.; Massaglia, S.

    2015-08-01

    Context. An equation of state (EoS) is a relation between thermodynamic state variables and it is essential for closing the set of equations describing a fluid system. Although an ideal EoS with a constant adiabatic index ? is the preferred choice owing to its simplistic implementation, many astrophysical fluid simulations may benefit from a more sophisticated treatment that can account for diverse chemical processes. Aims: In the present work we first review the basic thermodynamic principles of a gas mixture in terms of its thermal and caloric EoS by including effects like ionization, dissociation, and temperature dependent degrees of freedom such as molecular vibrations and rotations. The formulation is revisited in the context of plasmas that are either in equilibrium conditions (local thermodynamic- or collisional excitation-equilibria) or described by non-equilibrium chemistry coupled to optically thin radiative cooling. We then present a numerical implementation of thermally ideal gases obeying a more general caloric EoS with non-constant adiabatic index in Godunov-type numerical schemes. Methods: We discuss the necessary modifications to the Riemann solver and to the conversion between total energy and pressure (or vice versa) routinely invoked in Godunov-type schemes. We then present two different approaches for computing the EoS. The first employs root-finder methods and it is best suited for EoS in analytical form. The second is based on lookup tables and interpolation and results in a more computationally efficient approach, although care must be taken to ensure thermodynamic consistency. Results: A number of selected benchmarks demonstrate that the employment of a non-ideal EoS can lead to important differences in the solution when the temperature range is 500-104 K where dissociation and ionization occur. The implementation of selected EoS introduces additional computational costs although the employment of lookup table methods (when possible) can significantly reduce the overhead by a factor of ~ 3-4.

  17. Heat conduction in relativistic neutral gases revisited

    E-print Network

    A. L. Garcia-Perciante; A. R. Mendez

    2010-09-30

    The kinetic theory of dilute gases to first order in the gradients yields linear relations between forces and fluxes. The heat flux for the relativistic gas has been shown to be related not only to the temperature gradient but also to the density gradient in the representation where number density, temperature and hydrodynamic velocity are the independent state variables. In this work we show the calculation of the corresponding transport coefficients from the full Boltzmann equation and compare the magnitude of the relativistic correction.

  18. Imbalanced Feshbach-resonant Fermi gases

    NASA Astrophysics Data System (ADS)

    Radzihovsky, Leo; Sheehy, Daniel E.

    2010-07-01

    We present an overview of recent developments in species-imbalanced ('polarized') Feshbach-resonant Fermi gases. We summarize the current status of thermodynamics of these systems in terms of a phase diagram as a function of the Feshbach resonance detuning, polarization and temperature. We review instabilities of the s-wave superfluidity across the Bose-Einstein condensation-to-Bardeen-Cooper-Schrieffer crossover to phase separation, Fulde-Ferrell-Larkin-Ovchinnikov states, polarized molecular superfluidity and the normal state, driven by the species imbalance. We discuss different models and approximations of this system and compare their predictions with current experiments.

  19. Effect of Greenhouse Gases Dissolved in Seawater.

    PubMed

    Matsunaga, Shigeki

    2016-01-01

    A molecular dynamics simulation has been performed on the greenhouse gases carbon dioxide and methane dissolved in a sodium chloride aqueous solution, as a simple model of seawater. A carbon dioxide molecule is also treated as a hydrogen carbonate ion. The structure, coordination number, diffusion coefficient, shear viscosity, specific heat, and thermal conductivity of the solutions have been discussed. The anomalous behaviors of these properties, especially the negative pressure dependence of thermal conductivity, have been observed in the higher-pressure region. PMID:26729101

  20. Momentum Distributions of 1D Bose Gases

    NASA Astrophysics Data System (ADS)

    Xia, Lin; Wilson, Joshua M.; Zundel, Laura A.; Xu, Wei; Rigol, Marcos; Weiss, David S.

    2015-05-01

    Although the many-body wave functions of 1D Bose gases with ?-function interacting can be exactly calculated, it has been a theoretical challenge to extract their momentum distributions at intermediate coupling strengths. We will present precise measurements of 1D Bose gas momentum distributions in the strong and intermediate coupling regimes, and compare them to new theory calculations. We will emphasize our sensitivity to the predicted p-4 tail, and the sensitivity of the results to excitations out of the many-body ground state.

  1. Excitation and quenching of detonation in gases

    NASA Astrophysics Data System (ADS)

    Levin, V. A.; Manuilovich, I. S.; Markov, V. V.

    2010-12-01

    The results of investigations on the problems of initiation, propagation, and stabilization of detonation waves and flowing combustible gaseous mixtures are presented. To describe the flows, we used ideal perfect gas equations and two models of the detonation wave: the classical infinitely thin model and a model in which behind the shock wave chemical reactions described by the single-stage kinetics for propane- and methane-air combustible mixtures proceed. Investigations were carried out by both analytical and numerical methods based on the S. K. Godunov scheme on stationary and movable computational meshes with explicit resolution of the bow shock and the surfaces separating gases with different properties.

  2. Collisions in zero temperature Fermi gases

    E-print Network

    Subhadeep Gupta; Zoran Hadzibabic; James R. Anglin; Wolfgang Ketterle

    2003-07-03

    We examine the collisional behavior of two-component Fermi gases released at zero temperature from a harmonic trap. Using a phase-space formalism to calculate the collision rate during expansion, we find that Pauli blocking plays only a minor role for momentum changing collisions. As a result, for a large scattering cross-section, Pauli blocking will not prevent the gas from entering the collisionally hydrodynamic regime. In contrast to the bosonic case, hydrodynamic expansion at very low temperatures is therefore not evidence for fermionic superfluidity.

  3. Optical remote measurement of toxic gases

    NASA Technical Reports Server (NTRS)

    Grant, W. B.; Kagann, R. H.; McClenny, W. A.

    1992-01-01

    Enactment of the Clean Air Act Amendments (CAAA) of 1990 has resulted in increased ambient air monitoring needs for industry, some of which may be met efficiently using open-path optical remote sensing techniques. These techniques include Fourier transform spectroscopy, differential optical absorption spectroscopy, laser long-path absorption, differential absorption lidar, and gas cell correlation spectroscopy. With this regulatory impetus, it is an opportune time to consider applying these technologies to the remote and/or path-averaged measurement and monitoring of toxic gases covered by the CAAA. This article reviews the optical remote sensing technology and literature for that application.

  4. Catalytic Generation of Lift Gases for Balloons

    NASA Technical Reports Server (NTRS)

    Zubrin, Robert; Berggren, Mark

    2011-01-01

    A lift-gas cracker (LGC) is an apparatus that generates a low-molecular-weight gas (mostly hydrogen with smaller amounts of carbon monoxide and/or carbon dioxide) at low gauge pressure by methanol reforming. LGCs are undergoing development for use as sources of buoyant gases for filling zero-gauge-pressure meteorological and scientific balloons in remote locations where heavy, high-pressure helium cylinders are not readily available. LGCs could also be used aboard large, zero-gauge-pressure, stratospheric research balloons to extend the duration of flight.

  5. Traveling dark solitons in superfluid Fermi gases

    SciTech Connect

    Liao Renyuan; Brand, Joachim

    2011-04-15

    Families of dark solitons exist in superfluid Fermi gases. The energy-velocity dispersion and number of depleted particles completely determine the dynamics of dark solitons on a slowly varying background density. For the unitary Fermi gas, we determine these relations from general scaling arguments and conservation of local particle number. We find solitons to oscillate sinusoidally at the trap frequency reduced by a factor of 1/{radical}(3). Numerical integration of the time-dependent Bogoliubov-de Gennes equation determines spatial profiles and soliton-dispersion relations across the BEC-BCS crossover, and proves consistent with the scaling relations at unitarity.

  6. Radiation Basics

    MedlinePLUS

    EPA United States Environmental Protection Agency Search Search Radiation Protection Share Facebook Twitter Google+ Pinterest Contact Us ... are here: EPA Home » Radiation Protection » Radiation Basics Radiation Basics Radiation is energy. It can come from ...

  7. On segregation of noble gases in water-based Single Bubble Sonoluminescence

    NASA Astrophysics Data System (ADS)

    Levinsen, Mogens

    2011-03-01

    A long-standing issue in the field of long time stable water based single bubble sonoluminescence has been the close similarity of the spectra to that of blackbody radiation. Looking for the effects of possible segregation of noble gases has been suggested as a means to investigate whether the similarity is just a weird coincidence with the bubbles being on the whole transparent to their own radiation. We have investigated spectra from bubbles seeded with various mixtures of helium and neon with xenon and argon using a novel transformation that allows for a single parameter characterization of the spectra, with the surprising result that although no trace of segregation is found, the radiation seems to be highly thermalized in all cases.

  8. The Origin and Time Dependence of the Amount and Composition of Non-Constituent Gases Present in Crystal Growth Systems

    NASA Technical Reports Server (NTRS)

    Palosz, Witold

    1998-01-01

    Presence of different, non-constituent gases may be a critical factor in crystal growth systems. In Physical Vapor Transport processes the cras(es) can be used intentionally (to prevent excessively high, unstable growth conditions), or can evolve unintentionally during the course of the process (which may lead to undesired reduction in the -rowth rate). In melt growth, particularly under low gravity conditions (reduced hydrostatic pressure) the gas present in the system may contribute to formation of voids in the growing crystals and even to a separation of the crystal and the liquid phase [1]. On the other hand, some amount of gas may facilitate 'contactless' crystal growth particularly under reduced gravity conditions [2 - 6]. Different non-constituent gases may be present in growth ampoules, and their amount and composition may change during the crystallization process. Some gases can appear even in empty ampoules sealed originally under high vacuum: they may diffuse in from the outside, and/or desorb from the ampoule walls. Residual gases can also be generated by the source materials: even very high purity commercial elements and compounds may contain trace amounts of impurities, particularly oxides. The oxides may have low volatilities themselves but their reaction with other species, particularly carbon and hydrogen, may produce volatile compounds like water or carbon oxides. The non-constituent gases, either added initially to the system or evolved during the material processing, may diffuse out of the ampoule during the course of the experiment. Gases present outside (e.g. as a protective atmosphere or thermal conductor) may diffuse into the ampoule. In either case the growth conditions and the quality of the crystals may be affected. The problem is of a particular importance in sealed systems where the amount of the gases cannot be directly controlled. Therefore a reasonable knowledge and understanding of the origin, composition, magnitude, and change with time of gases present in sealed ampoules may be important for a meaningful control and interpretation of crystal growth processes. This problem is of a particular importance for processing of electronic materials in space because (i) safety considerations require using sealed systems only, and (ii) high cost of crystal growth experiments in microgravity calls for a throughout, accurate description of the processing conditions necessary for a meaningful, efficient, and conclusive interpretation of the space results. In this paper we present the results of our extensive studies on gases in closed crystal growth systems which include: (a) Degassing properties of fused silica; (b) Generation of inert gases by source materials (CdTe, ZnTe, CdZnTe, ZnSe, PbTe, PbSe, PbSeTe); (c) Diffusive cas losses from silica glass ampoules.

  9. HELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153 Greenhouse gases andGreenhouse gases and

    E-print Network

    Zevenhoven, Ron

    warming potential (GWP) % of US GHG emissions (1990) % of US GHG emissions (1998) Carbon dioxide, CO22 1 Fuel cells Removal after fuel reforming or from off-gas "Hydrocarb" etc. Removal of carbon from-depleting gases ·· COCO22 removal for gas purificationremoval for gas purification ·· COCO22 removal

  10. The search for active release of volcanic gases on Mars

    NASA Astrophysics Data System (ADS)

    Khayat, Alain; Villanueva, Geronimo; Mumma, Michael; Tokunaga, Alan

    2015-11-01

    The study of planetary atmospheres by means of spectroscopy is important for understanding their origin and evolution. The presence of short-lived trace gases in the martian atmosphere would imply recent production, for example, by ongoing geologic activity. On Earth, sulfur dioxide (SO2), sulfur monoxide (SO) and hydrogen sulfide (H2S) are the main sulfur-bearing gases released during volcanic outgassing. Carbonyl sulfide (OCS), also released from some volcanoes on Earth (e.g., Erebus and Nyiragongo), could be formed by reactions involving SO2 or H2S inside magma chambers. We carried out the first ground-based, semi-simultaneous, multi-band and multi-species search for such gases above the Tharsis and Syrtis volcanic regions on Mars. The submillimeter search extended between 23 November 2011 and 13 May 2012 which corresponded to Mars’ mid Northern Spring and early Northern Summer seasons (Ls = 34–110°). The strong submillimeter rotational transitions of SO2, SO and H2S were targeted using the high-resolution heterodyne receiver (aka Barney) on the Caltech Submillimeter Observatory. We reached sensitivities sufficient to detect a volcanic release on Mars that is 4% of the SO2 released continuously from Kilauea volcano in Hawaii, or 5% that of the Masaya volcano in Nicaragua. The infrared search covered OCS in its combination band (?2+?3) at 3.42 ?m at two successive Mars years, during Mars’ late Northern Spring and mid Northern Summer seasons, spanning Ls= 43º and Ls= 147º. The targeted volcanic districts were observed during the two intervals, 14 Dec. 2011 to 6 Jan. 2012 in the first year, and 30 May 2014 to 16 June 2014 in the second year, using the high resolution infrared spectrometer (CSHELL) on NASA’s Infrared Telescope Facility (NASA/IRTF). We will present our results and discuss their implications for current volcanic outgassing activity on the red planet. We gratefully acknowledge support from the NASA Planetary Astronomy Program under NASA contract NNH14CK55B that supported A.K. and A.T., RTOP 344-32-07 and NASA’s Astrobiology Program (RTOP 344-53-51) that supported M.J.M., and G.L.V.

  11. Cope with dissolved gases in pump calculations

    SciTech Connect

    Chen, C.C. )

    1993-10-01

    The pressure of the liquid at the inlet of a centrifugal pump must be high enough to prevent vaporization within the pump, because this vaporization hinders the pumping and can damage the impellers. This pressure requirement must be taken into account when deciding how high to place the pump feed vessel relative to the height of the pump itself. Basically, the pump suction pressure must be greater than the fluid's vapor pressure at the pumping temperature. The difference between pump suction pressure and vapor pressure is the net positive suction head (NPSH). For cases in which the liquid contains no dissolved gases, the vapor-pressure determination is straightforward. With dissolved gases, the situation is more complicated, because vapor-pressure data for such systems are usually not at hand. Adding to the complication is the fact that centrifugal pumps generally can, as it happens, tolerate a small amount of vapor at the impeller eye. If the solubility of the dissolved gas is low and the temperature is far below the boiling point of liquid, the amount of vapor released in a pump is likely not to exceed the tolerable value unless the pressure reduction is substantial.

  12. Emissions of sulfur gases from wetlands

    NASA Technical Reports Server (NTRS)

    Hines, Mark E.

    1992-01-01

    Data on the emissions of sulfur gases from marine and freshwater wetlands are summarized with respect to wetland vegetation type and possible formation mechanisms. The current data base is largest for salt marshes inhabited by Spartina alterniflora. Both dimethyl sulfide (DMS) and hydrogen sulfide (H2S) dominate emissions from salt marshes, with lesser quantities of methyl mercaptan (MeSH), carbonyl sulfide (COS), carbon disulfide (CS2) and dimethyl disulfide (DMDS) being emitted. High emission rates of DMS are associated with vegetation that produces the DMS precursor dimethylsulfonionpropionate (DMSP). Although large quantities of H2S are produced in marshes, only a small percentage escapes to the atmosphere. High latitude marshes emit less sulfur gases than temperate ones, but DMS still dominates. Mangrove-inhabited wetlands also emit less sulfur than temperate S. alterniflora marshes. Few data are available on sulfur gas emissions from freshwater wetlands. In most instances, sulfur emissions from temperate freshwater sites are low. However, some temperate and subtropical freshwater sites are similar in magnitude to those from marine wetlands which do not contain vegetation that produces DMSP. Emissions are low in Alaskan tundra but may be considerably higher in some bogs and fens.

  13. Study of electron transport in hydrocarbon gases

    SciTech Connect

    Hasegawa, H.; Date, H.

    2015-04-07

    The drift velocity and the effective ionization coefficient of electrons in the organic gases, C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, C{sub 2}H{sub 6}, CH{sub 3}OH, C{sub 2}H{sub 5}OH, C{sub 6}H{sub 6}, and C{sub 6}H{sub 5}CH{sub 3}, have been measured over relatively wide ranges of density-reduced electric fields (E/N) at room temperature (around 300?K). The drift velocity was measured, based on the arrival-time spectra of electrons by using a double-shutter drift tube over the E/N range from 300 to 2800 Td, and the effective ionization coefficient (?????) was determined by the steady-state Townsend method from 150 to 3000 Td. Whenever possible, these parameters were compared with those available in the literature. It has been shown that the swarm parameters for these gases have specific tendencies, depending on their molecular configurations.

  14. Snowpack Chemistry of Reactive Gases at Station Concordia, Antarctica

    NASA Astrophysics Data System (ADS)

    Helmig, Detlev; Mass, Alex; Hueber, Jacques; Fain, Xavier; Dommergue, Aurelien; Barbero, Albane; Savarino, Joel

    2013-04-01

    During December 2012 a new experiment for the study of snow photochemical processes and surface gas exchange was installed at Dome Concordia, Antarctica. The experiment consists of two sampling manifolds ('snow tower') which facilitate the withdrawal of interstitial firn air from four depths in the snowpack and from above the surface. One of these snow towers can be shaded for investigation of the dependency of snow chemistry on solar radiation. A nearby 12 m meteorological tower facilitates above surface turbulence and trace gas gradient measurements. Temperature profiles and UV and IR light penetration are monitored in the snowpack. Air samples are directed through sampling lines to a nearby underground laboratory that houses the experiment control system and gas monitors. The system is fully automated, sampling gases from the array of inlet ports sequentially, and is intended to be operated continuously for a full annual cycle. The computerized control system can be accessed remotely for data retrieval and quality control and for configuring experimental details. Continuous gas measurements include ozone, nitrogen oxides, methane, carbon monoxide, and gaseous elemental mercury. Whole air samples were sampled on four occasions for volatile organic compound analysis. The objective of this research is the study of the year-round snowpack gas chemistry and its dependency on snowpack and above surface physical and environmental conditions. A particular emphasis will be the investigation of the effects of increased UV radiation during the occurrence of the stratospheric ozone hole. We will present the conceptual design of the experiment and data examples from the first three months of the experiment.

  15. Non-thermal plasma for exhaust gases treatment

    NASA Astrophysics Data System (ADS)

    Alva R., Elvia; Pacheco P., Marquidia; Gómez B., Fernando; Pacheco P., Joel; Colín C., Arturo; Sánchez-Mendieta, Víctor; Valdivia B., Ricardo; Santana D., Alfredo; Huertas C., José; Frías P., Hilda

    2015-09-01

    This article describes a study on a non-thermal plasma device to treat exhaust gases in an internal combustion engine. Several tests using a plasma device to treat exhaust gases are conducted on a Honda GX200-196 cm3 engine at different rotational speeds. A plasma reactor could be efficient in degrading nitrogen oxides and particulate matter. Monoxide and carbon dioxide treatment is minimal. However, achieving 1%-3% degradation may be interesting to reduce the emission of greenhouse gases.

  16. Non-thermal plasma for exhaust gases treatment

    NASA Astrophysics Data System (ADS)

    Alva R., Elvia; Pacheco P., Marquidia; Gómez B., Fernando; Pacheco P., Joel; Colín C., Arturo; Sánchez-Mendieta, Víctor; Valdivia B., Ricardo; Santana D., Alfredo; Huertas C., José; Frías P., Hilda

    2015-08-01

    This article describes a study on a non-thermal plasma device to treat exhaust gases in an internal combustion engine. Several tests using a plasma device to treat exhaust gases are conducted on a Honda GX200-196 cm3 engine at different rotational speeds. A plasma reactor could be efficient in degrading nitrogen oxides and particulate matter. Monoxide and carbon dioxide treatment is minimal. However, achieving 1%-3% degradation may be interesting to reduce the emission of greenhouse gases.

  17. Suspended two-dimensional electron and hole gases

    SciTech Connect

    Kazazis, D.; Bourhis, E.; Gierak, J.; Gennser, U.; Bourgeois, O.; Antoni, T.

    2013-12-04

    We report on the fabrication of fully suspended two-dimensional electron and hole gases in III-V heterostructures. Low temperature transport measurements verify that the properties of the suspended gases are only slightly degraded with respect to the non-suspended gases. Focused ion beam technology is used to pattern suspended nanostructures with minimum damage from the ion beam, due to the small width of the suspended membrane.

  18. Method for controlling corrosion in thermal vapor injection gases

    DOEpatents

    Sperry, John S. (Houston, TX); Krajicek, Richard W. (Houston, TX)

    1981-01-01

    An improvement in the method for producing high pressure thermal vapor streams from combustion gases for injection into subterranean oil producing formations to stimulate the production of viscous minerals is described. The improvement involves controlling corrosion in such thermal vapor gases by injecting water near the flame in the combustion zone and injecting ammonia into a vapor producing vessel to contact the combustion gases exiting the combustion chamber.

  19. Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC

    PubMed Central

    Brühl, C; Lelieveld, J; Tost, H; Höpfner, M; Glatthor, N

    2015-01-01

    Multiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO2, the latter from low-latitude and midlatitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. Marine dimethyl sulfide (DMS) and other SO2 sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost stratosphere. Estimates of volcanic SO2 emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or Stratospheric Aerosol and Gases Experiment for the spatial distribution. The 10 year SO2 and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of stratospheric background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m2. For stratospheric sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m2 is calculated, moderating climate warming, while for the major Pinatubo eruption the simulated forcing reaches 5W/m2, leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions. PMID:25932352

  20. Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC

    NASA Astrophysics Data System (ADS)

    Brühl, C.; Lelieveld, J.; Tost, H.; Höpfner, M.; Glatthor, N.

    2015-03-01

    Multiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO2, the latter from low-latitude and midlatitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. Marine dimethyl sulfide (DMS) and other SO2 sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost stratosphere. Estimates of volcanic SO2 emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or Stratospheric Aerosol and Gases Experiment for the spatial distribution. The 10 year SO2 and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of stratospheric background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m2. For stratospheric sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m2 is calculated, moderating climate warming, while for the major Pinatubo eruption the simulated forcing reaches 5W/m2, leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions.

  1. Joint modeling of thermal creep and radiation damage interaction with gas permeability and release dynamics: The role of percolation

    NASA Astrophysics Data System (ADS)

    Ovaska, M.; Alava, M. J.

    2015-10-01

    Nuclear fuel material is an example of a sintered, porous ceramic material. We formulate a two-dimensional model which couples three physical mechanisms in the material: (scalar) damage accumulation by thermal creep and radiation effects, porosity changes due to the damage, and the time-dependent diffusion of (radiation-induced) gases in the pore system thus created. The most important effect in the dynamics arises from the process where the pore system is swept through the percolation transition. The main conclusions that can be drawn concern the fractional gas release and its dependence on the three effects present in the damage dynamics: creep, radiation-induced bubble formation, and recovery due to bubble closure. In the main, the model reproduces the experimentally observed quick gas release phenomenon qualitatively.

  2. Hydrogen Peroxide Enhances Removal of NOx from Flue Gases

    NASA Technical Reports Server (NTRS)

    Collins, Michelle M.

    2005-01-01

    Pilot scale experiments have demonstrated a method of reducing the amounts of oxides of nitrogen (NOx) emitted by industrial boilers and powerplant combustors that involves (1) injection of H2O2 into flue gases and (2) treatment of the flue gases by caustic wet scrubbing like that commonly used to remove SO2 from combustion flue gases. Heretofore, the method most commonly used for removing NOx from flue gases has been selective catalytic reduction (SCR), in which the costs of both installation and operation are very high. After further development, the present method may prove to be an economically attractive alternative to SCR.

  3. Workshop Report on Managing Solar Radiation

    NASA Technical Reports Server (NTRS)

    Lane, Lee (Compiler); Caldeira, Ken (Compiler); Chatfield, Robert (Compiler); Langhoff, Stephanie (Compiler)

    2007-01-01

    The basic concept of managing Earth's radiation budget is to reduce the amount of incoming solar radiation absorbed by the Earth so as to counterbalance the heating of the Earth that would otherwise result from the accumulation of greenhouse gases. The workshop did not seek to decide whether or under what circumstances solar radiation management should be deployed or which strategies or technologies might be best, if it were deployed. Rather, the workshop focused on defining what kinds of information might be most valuable in allowing policy makers more knowledgeably to address the various options for solar radiation management.

  4. Metamaterials for Cherenkov Radiation Based Particle Detectors

    SciTech Connect

    Tyukhtin, A. V.; Schoessow, P.; Kanareykin, A.; Antipov, S.

    2009-01-22

    Measurement of Cherenkov radiation (CR) has long been a useful technique for charged particle detection and beam diagnostics. We are investigating metamaterials engineered to have refractive indices tailored to enhance properties of CR that are useful for particle detectors and that cannot be obtained using conventional media. Cherenkov radiation in dispersive media with a large refractive index differs significantly from the same effect in conventional detector media, like gases or aerogel. The radiation pattern of CR in dispersive metamaterials presents lobes at very large angles with respect to particle motion. Moreover, the frequency and particle velocity dependence of the radiated energy can differ significantly from CR in a conventional dielectric medium.

  5. Separation of rare gases and chiral molecules by selective binding in porous organic cages.

    PubMed

    Chen, Linjiang; Reiss, Paul S; Chong, Samantha Y; Holden, Daniel; Jelfs, Kim E; Hasell, Tom; Little, Marc A; Kewley, Adam; Briggs, Michael E; Stephenson, Andrew; Thomas, K Mark; Armstrong, Jayne A; Bell, Jon; Busto, Jose; Noel, Raymond; Liu, Jian; Strachan, Denis M; Thallapally, Praveen K; Cooper, Andrew I

    2014-10-01

    The separation of molecules with similar size and shape is an important technological challenge. For example, rare gases can pose either an economic opportunity or an environmental hazard and there is a need to separate these spherical molecules selectively at low concentrations in air. Likewise, chiral molecules are important building blocks for pharmaceuticals, but chiral enantiomers, by definition, have identical size and shape, and their separation can be challenging. Here we show that a porous organic cage molecule has unprecedented performance in the solid state for the separation of rare gases, such as krypton and xenon. The selectivity arises from a precise size match between the rare gas and the organic cage cavity, as predicted by molecular simulations. Breakthrough experiments demonstrate real practical potential for the separation of krypton, xenon and radon from air at concentrations of only a few parts per million. We also demonstrate selective binding of chiral organic molecules such as 1-phenylethanol, suggesting applications in enantioselective separation. PMID:25038731

  6. Separation of rare gases and chiral molecules by selective binding in porous organic cages

    NASA Astrophysics Data System (ADS)

    Chen, Linjiang; Reiss, Paul S.; Chong, Samantha Y.; Holden, Daniel; Jelfs, Kim E.; Hasell, Tom; Little, Marc A.; Kewley, Adam; Briggs, Michael E.; Stephenson, Andrew; Thomas, K. Mark; Armstrong, Jayne A.; Bell, Jon; Busto, Jose; Noel, Raymond; Liu, Jian; Strachan, Denis M.; Thallapally, Praveen K.; Cooper, Andrew I.

    2014-10-01

    The separation of molecules with similar size and shape is an important technological challenge. For example, rare gases can pose either an economic opportunity or an environmental hazard and there is a need to separate these spherical molecules selectively at low concentrations in air. Likewise, chiral molecules are important building blocks for pharmaceuticals, but chiral enantiomers, by definition, have identical size and shape, and their separation can be challenging. Here we show that a porous organic cage molecule has unprecedented performance in the solid state for the separation of rare gases, such as krypton and xenon. The selectivity arises from a precise size match between the rare gas and the organic cage cavity, as predicted by molecular simulations. Breakthrough experiments demonstrate real practical potential for the separation of krypton, xenon and radon from air at concentrations of only a few parts per million. We also demonstrate selective binding of chiral organic molecules such as 1-phenylethanol, suggesting applications in enantioselective separation.

  7. The Oceanic Source of Trace Gases Now and in the Future

    NASA Astrophysics Data System (ADS)

    Liss, P. S.; Turner, S. M.; Martin, J. T.; Frances, H. E.; Valia, A. A.; Meike, V.; Adele, C. L.

    2008-12-01

    A complex cocktail of gases exchange between the atmosphere and oceans and many of the trace gases produced in seawater are considered to play important roles in climate and atmospheric chemistry. The strength of the biogenic marine source depends on a large number of factors that can be categorised as the magnitude of the net formation processes (production - destruction) and the kinetics of the sea-to-air transfer. It is recognised that the rise of anthropogenic CO2 in the atmosphere is already affecting the marine environment, with an average 30% increase in H+ ions in surface waters since pre-industrial times. The decrease in pH is only one of the factors expected to alter over the next century during which atmospheric CO2 will continue to rise. Model predictions suggest significant physical and biogeochemical changes (e.g. surface water temperature, wind speed, stratification, nutrient supply, phytoplankton community structure) that will likely affect many of the processes controlling sea-air gas exchange and fluxes to the atmosphere. We will present data showing how acidification of seawater and changes in nutrients may affect the net production of dimethyl sulphide and halogenated gases in seawater. In addition, we will discuss how the predicted changes in wind speed and seawater temperature may impinge on sea-air transfer and address the potential direction of change in the fluxes of a number of different gases, including ammonia, to the atmosphere.

  8. Isotopic studies of rare gases in terrestrial samples and natural nucleosynthesis

    SciTech Connect

    Not Available

    1990-07-01

    This project is concerned with research in rare gas mass spectrometry. We read the natural record that isotopes of the rare gases provide. We study fluids using a system (RARGA) that is sometimes deployed in the field. In 1990 there was a strong effort to reduce the backlog of RARGA samples on hand, so that it was a year of intensive data gathering. Samples from five different areas in the western United States and samples from Guatemala and Australia were analyzed. In a collaborative study we also began analyzing noble gases from rocks associated with the fluids. An important objective, continuing in 1991, is to understand better the reasons for somewhat elevated {sup 3}He/{sup 4}He ratios in regions where there is no contemporary volcanism which could produce the effect by addition of mantle helium. Our helium data have given us and our collaborators some insights, which are to be followed up, into gold mineralization in geothermal regions. Our DOE work in calibrating a sensitive laser microprobe mass spectrometer for noble gases in fluid inclusions continues. Having completed a series of papers on noble gases in diamonds, we next will attempt to make precise isotopic measurements on xenon from mantle sources, in search of evidence for terrestrially elusive {sup 244}Pu decay.

  9. Revised Variable Soft Sphere and Lennard-Jones Model Parameters for Eight Common Gases up to 2200 K

    NASA Astrophysics Data System (ADS)

    Weaver, Andrew B.; Alexeenko, Alina A.

    2015-06-01

    Revised parameters for variable soft sphere (VSS) and Lennard-Jones (L-J) (6-12) models are presented for eight common gases in the temperature range 20-2200 K. The new parameters are based on a critical review of experimental measurements and ab-initio calculations of shear viscosity and self-diffusion coefficients. The optimized parameters are assessed relative to experimental measurements and ab-initio calculations of thermal conductivity. Results indicate most significant improvements for the VSS model occur when considering lighter gases where repulsive forces are more important. The agreement with transport property measurements for He gas extends to much higher temperatures using the revised parameters. The accuracy of the L-J model is more significantly improved when considering the heavier gases for which attractive forces are important over a wider temperature range.

  10. The History of Planetary Degassing as Recorded by Noble Gases

    NASA Astrophysics Data System (ADS)

    Porcelli, D.; Turekian, K. K.

    2003-12-01

    Noble gases provide unique clues to the structure of the Earth and the degassing of volatiles into the atmosphere. Since the noble gases are highly depleted in the Earth, their isotopic compositions are prone to substantial changes due to radiogenic additions, even from scarce parent elements and low-yield nuclear processes. Therefore, noble gas isotopic signatures of major reservoirs reflect planetary differentiation processes that generate fractionations between these volatiles and parent elements. These signatures can be used to construct planetary degassing histories that have relevance to the degassing of a variety of chemical species as well.It has long been recognized that the atmosphere is not simply a remnant of the volatiles that surrounded the forming Earth with the composition of the early solar nebula. It was also commonly thought that the atmosphere and oceans were derived from degassing of the solid Earth over time (Brown, 1949; Suess, 1949; Rubey, 1951). Subsequent improved understanding of the processes of planet formation, however, suggests that substantial volatile inventories could also have been added directly to the atmosphere. The characteristics of the atmosphere therefore reflect the acquisition of volatiles by the solid Earth during formation (see Pepin and Porcelli, 2002; Chapter 4.12), as well as the history of degassing from the mantle. The precise connection between volatiles now emanating from the Earth and the long-term evolution of the atmosphere are key subjects of modeling efforts, and are discussed below.Major advances in understanding the behavior of terrestrial volatiles have been made based upon observations on the characteristics of noble gases that remain within the Earth. Various models have been constructed that define different components and reservoirs in the planetary interior, how materials are exchanged between them, and how the noble gases are progressively transferred to the atmosphere (see Chapter 2.06). While there remain many uncertainties, an overall process of planetary degassing can be discerned. The present chapter discusses the constraints provided by the noble gases and how these relate to the degassing of the volatile molecules formed from nitrogen, carbon, and hydrogen (see also Chapter 3.04). The evolution of particular atmospheric molecular species, such as CO2, that are controlled by interaction with other crustal reservoirs and which reflect surface chemical conditions, are primarily discussed elsewhere (Chapter 8.09).Noble gases provide the most detailed constraints on planetary degassing. A description of the available noble gas data that must be incorporated into any Earth degassing history is provided first in Section 4.11.2, and the constraints on the total extent of degassing of the terrestrial interior are provided in Section 4.11.3. Noble gas degassing models that have been used to describe and calculate degassing histories of both the mantle ( Section 4.11.4) and the crust ( Section 4.11.5) are then presented. These discussions then provide the context for an evaluation of major volatile cycles in the Earth ( Section 4.11.6), and speculations about the degassing of the other terrestrial planets ( Section 4.11.7), Mars and Venus, that are obviously based on much more limited data. The processes controlling mantle degassing are clearly related to the structure of the mantle, as discussed in Section 4.11.4. Further descriptions of mantle noble gas reservoirs and transport processes based upon multi-tracer variations in mantle-derived materials are provided in Chapter 2.06. An important aspect is the origin of planetary volatiles and whether initial incorporation was into the solid Earth or directly to the atmosphere; these issues are discussed in detail in Chapter 4.12. Basic noble gas elemental and isotopic characteristics are given in Ozima and Podosek (2001) and Porcelli et al. (2002). The major nuclear processes that produce noble gases within the solid Earth, and the half-lives of the major parental nuclides, are given in Table 1. Table 1. Major

  11. Radiation Protection

    MedlinePLUS

    EPA United States Environmental Protection Agency Search Search Radiation Protection Share Facebook Twitter Google+ Pinterest Contact Us Radiation Protection Document Library View and download EPA radiation ...

  12. Circumsolar radiation

    SciTech Connect

    Watt, A.D.

    1980-04-01

    A quantitative knowledge of circumsolar radiation is important in the design of focusing type solar collectors, and is also of interest to those calculating the performance of all types of collectors. The primary objective of this study is the development of a model which will permit estimation of circumsolar radiation based on solar and meteorological input data. The results of observations are presented including radiance characteristics and time variations of the circumsolar component at a number of locations. The characteristics of the atmosphere are presented with primary emphasis on large particles. Physical models of circumsolar radiation are developed. The results of observed clear day only and all day average monthly values at Albuquerque, NM are shown. Also shown are calculated values for both clear and average days based on the physical model. The model results are based on: long term average turbidity values, derived average pollen loadings, and actual monthly average sky cover values for the years shown. Regression analysis is employed to determine the circumsolar values based on observed solar radiation and atmospheric parameters. The regression derived models show that fairly good agreement can be obtained between observed and calculated monthly average circumsolar ratios by simple expressions employing only the active cavity radiometer values. (WHK)

  13. Atmospheric effects on radiation measurements

    NASA Technical Reports Server (NTRS)

    Jurica, G. M.

    1973-01-01

    Two essentially distinct regions of the electromagnetic spectrum are discussed: (1) the scattering region in which the radiation energy is provided by the incident solar flux; and (2) the infrared region in which emission by the earth's surface and atmospheric gases supply radiative energy. In each of these spectral regions the atmosphere performs its dual function with respect to a remote sensing measurement of surface properties. The atmosphere acts both as a filter and as a noise generator removing and obscuring sought after information. Nevertheless, with proper application of concepts such as have been considered, it will be possible to remove these unwanted atmospheric effects and to improve identification techniques being developed.

  14. Topics in multi-component ultracold gases and gauge fields

    NASA Astrophysics Data System (ADS)

    Ozawa, Tomoki

    In this thesis, we present theoretical studies on three topics related to multi-component ultracold gases and gauge fields. The first topic that we discuss is artificial gauge fields in ultracold gases. Recently, methods to create artificial gauge fields coupled to neutral ultracold systems using a light-induced Berry's connection have been rapidly developing. These methods are not only capable of creating Abelian gauge fields, such as a conventional magnetic field, but also non-Abelian gauge fields, which opens a way to explore and simulate a wide variety of physical models. In this thesis, we discuss various properties of bosons with Rashba-Dresselhaus spin-orbit coupling, which is a special type of non-Abelian gauge field. We investigate the stability of Bose-Einstein condensates with Rashba-Dresselhaus spin-orbit coupling, and show that the condensates are stable against quantum and thermal fluctuations. We also consider the renormalization of the bare interaction by calculating the t-matrix and its consequence on the ground state phase diagrams. The second topic discussed here is three-component ultracold fermionic systems. It is known that ferromagnetism and superfluidity can coexist at low enough temperature in three-component ultracold fermions. In this thesis, we elucidate how fermionic pairing and population imbalance enhance each other. We also describe a crossover from Bardeen-Cooper-Schrieffer state of fermionic pairing state to the limit of Bose-Einstein condensate of three weakly interacting species of molecules, as the interaction increases. Furthermore, we find an interesting similarity in the free energies between three-component ultracold fermions and quantum chromodynamics. The last topic discussed here is Niels Bohr's double-slit interference gedankenexperiment with charged particles, which argues that the consistency of elementary quantum mechanics requires that the electromagnetic field must be quantized. In the experiment a particle's path through the slits is determined by measuring the Coulomb field that it produces at large distances. Under these conditions the interference pattern must be suppressed; otherwise quantum mechanics is not consistent. The mechanism for the suppression of the interference pattern is that, as the particle's trajectory is bent in diffraction by the slits, it must radiate and the radiation must carry away phase information. Thus, the radiation field must be a quantized dynamical degree of freedom. We also consider the related setup in which one attempts to determine the path of a massive particle through an interferometer by measuring the Newtonian gravitational potential the particle produces. In this case, we show that the interference pattern would have to be finer than the Planck length and thus indiscernible. Therefore, unlike for the electromagnetic field, Bohr's argument does not imply that the gravitational field must be quantized.

  15. Free electron in compressed inert gases

    SciTech Connect

    Gordon, E. B. Smirnov, B. M.

    2008-08-15

    The behavior of excess and intrinsic free electrons inside compressed inert gases is described as a function of pressure by using a pairwise approximation for the electron interaction with atomic surroundings. The change of sign from negative to positive for the xenon atom electric potential inside condensed xenon is predicted to occur at a pressure around 3 GPa, preventing slow electron embedding into solid xenon from the gas phase at higher pressure. To overcome this difficulty, the electrons should be injected into a solid sample just before its pulsed shock loading. The ionization of xenon by pressure and its further metallization are described by decreasing the forbidden gap at the expense of increasing the xenon ground electronic term and simultaneous splitting of the upper ionized electronic state. A good coincidence between the calculated and measured pressure of the dielectric-metal transition in xenon is demonstrated.

  16. Peltier Cooling of Fermionic Quantum Gases

    NASA Astrophysics Data System (ADS)

    Grenier, Ch.; Georges, A.; Kollath, C.

    2014-11-01

    We propose a cooling scheme for fermionic quantum gases, based on the principles of the Peltier thermoelectric effect and energy filtering. The system to be cooled is connected to another harmonically trapped gas acting as a reservoir. The cooling is achieved by two simultaneous processes: (i) the system is evaporatively cooled, and (ii) cold fermions from deep below the Fermi surface of the reservoir are injected below the Fermi level of the system, in order to fill the "holes" in the energy distribution. This is achieved by a suitable energy dependence of the transmission coefficient connecting the system to the reservoir. The two processes can be viewed as simultaneous evaporative cooling of particles and holes. We show that both a significantly lower entropy per particle and faster cooling rate can be achieved in this way than by using only evaporative cooling.

  17. Shock Wave Dynamics in Weakly Ionized Gases

    NASA Technical Reports Server (NTRS)

    Johnson, Joseph A., III

    1998-01-01

    We have begun a comprehensive series of analyses and experiments to study the basic problem of shock wave dynamics in ionized media. Our objective is to isolate the mechanisms that are responsible for the decrease in the shock amplitude and also to determine the relevant plasma parameters that will be required for a drag reduction scheme in an actual high altitude hypersonic flight. Specifically, we have initiated a program of analyses and measurements with the objective of (i) fully characterizing the propagation dynamics in plasmas formed in gases of aerodynamic interest, (ii) isolating the mechanisms responsible for the decreased shock strength and increased shock velocity, (iii) extrapolating the laboratory observations to the technology of supersonic flight.

  18. Second Sound in Ultracold Atomic Gases

    E-print Network

    Lev P. Pitaevskii; Sandro Stringari

    2015-10-05

    We provide an overview of the recent theoretical and experimental advances in the study of second sound in ultracold atomic gases. Starting from the Landau two fluid hydrodynamic equations we develop the theory of first and second sound in various configurations characterized by different geometries and quantum statistics. These include the weakly interacting 3D Bose gas, the strongly interacting Fermi gas at unitarity in the presence of highly elongated traps and the dilute 2D Bose gas, characterized by the Berezinskii-Kosterlitz-Thouless transition. An explicit comparison with the propagation of second sound in liquid Helium is carried out to elucidate the main analogies and differences. We also make an explicit comparison with the available experimental data and point out the crucial role played by the superfluid density in determining the temperature dependence of the second sound speed.

  19. Adsorption of Atmospheric Gases on Pu Surfaces

    SciTech Connect

    Nelson, A J; Holliday, K S; Stanford, J A; Grant, W K; Erler, R G; Allen, P G; McLean, W; Roussel, P

    2012-03-29

    Surface adsorption represents a competition between collision and scattering processes that depend on surface energy, surface structure and temperature. The surface reactivity of the actinides can add additional complexity due to radiological dissociation of the gas and electronic structure. Here we elucidate the chemical bonding of gas molecules adsorbed on Pu metal and oxide surfaces. Atmospheric gas reactions were studied at 190 and 300 K using x-ray photoelectron spectroscopy. Evolution of the Pu 4f and O 1s core-level states were studied as a function of gas dose rates to generate a set of Langmuir isotherms. Results show that the initial gas dose forms Pu{sub 2}O{sub 3} on the Pu metal surface followed by the formation of PuO{sub 2} resulting in a layered oxide structure. This work represents the first steps in determining the activation energy for adsorption of various atmospheric gases on Pu.

  20. Concomitant modulated superfluidity in polarized Fermi gases

    SciTech Connect

    Baksmaty, L. O.; Lu Hong; Pu Han; Bolech, C. J.

    2011-02-15

    Recent ground-breaking experiments studying the effects of spin polarization on pairing in unitary Fermi gases encountered mutual qualitative and quantitative discrepancies which seem to be a function of the confining geometry. Using numerical algorithms we study the solution space for a three-dimensional fully self-consistent formulation of realistic systems with up to 10{sup 5} atoms. A study of the three types of solutions obtained demonstrates a tendency toward metastability as the confining geometry is elongated. One of these solutions, which is consistent with Rice experiments at high trap aspect ratio, supports a state strikingly similar to the long sought Fulde-Ferrel-Larkin-Ovchinnikov state. Our study helps to resolve the long-standing controversy concerning the discrepancies between the findings from two different experimental groups and highlights the versatility of actual-size numerical calculations for investigating inhomogeneous fermionic superfluids.

  1. Clustering and phases of compartmentalized granular gases.

    PubMed

    Chen, K C; Li, C C; Lin, C H; Guo, G H

    2009-02-01

    This paper experimentally investigates the clustering conditions for compartmentalized monodisperse granular gases, determining the critical particle number and condensation granular temperature at the gas-clustering transition. When one heavier intruding particle is added to a monodisperse gas, it is found that the condensation temperature decreases with the ratio of the mass of the intruding particle to that of the background particle. This phenomenon can be mathematically characterized by a proposed linear relation, which is reminiscent of a relation between the freezing point depression for a solvent and the concentration of an added solute. Finally we perform various tests by changing the numbers of two types of particles in bidisperse granular mixtures to construct the phase diagrams, which present the range of the five different states, namely, homogeneous gas, unstable-gas, one-clustering, two-clustering, and granular oscillation states. PMID:19391739

  2. Peltier cooling of fermionic quantum gases.

    PubMed

    Grenier, Ch; Georges, A; Kollath, C

    2014-11-14

    We propose a cooling scheme for fermionic quantum gases, based on the principles of the Peltier thermoelectric effect and energy filtering. The system to be cooled is connected to another harmonically trapped gas acting as a reservoir. The cooling is achieved by two simultaneous processes: (i) the system is evaporatively cooled, and (ii) cold fermions from deep below the Fermi surface of the reservoir are injected below the Fermi level of the system, in order to fill the "holes" in the energy distribution. This is achieved by a suitable energy dependence of the transmission coefficient connecting the system to the reservoir. The two processes can be viewed as simultaneous evaporative cooling of particles and holes. We show that both a significantly lower entropy per particle and faster cooling rate can be achieved in this way than by using only evaporative cooling. PMID:25432033

  3. Voluntary reporting of greenhouse gases 1997

    SciTech Connect

    1999-05-01

    The Voluntary Reporting of Greenhouse Gases Program, required by Section 1605(b) of the Energy Policy Act of 1992, records the results of voluntary measures to reduce, avoid, or sequester greenhouse gas emissions. In 1998, 156 US companies and other organizations reported to the Energy information Administration that, during 1997, they had achieved greenhouse gas emission reductions and carbon sequestration equivalent to 166 million tons of carbon dioxide, or about 2.5% of total US emissions for the year. For the 1,229 emission reduction projects reported, reductions usually were measured by comparing an estimate of actual emissions with an estimate of what emissions would have been had the project not been implemented.

  4. From ultracold Fermi Gases to Neutron Stars

    NASA Astrophysics Data System (ADS)

    Salomon, Christophe

    2012-02-01

    Ultracold dilute atomic gases can be considered as model systems to address some pending problem in Many-Body physics that occur in condensed matter systems, nuclear physics, and astrophysics. We have developed a general method to probe with high precision the thermodynamics of locally homogeneous ultracold Bose and Fermi gases [1,2,3]. This method allows stringent tests of recent many-body theories. For attractive spin 1/2 fermions with tunable interaction (^6Li), we will show that the gas thermodynamic properties can continuously change from those of weakly interacting Cooper pairs described by Bardeen-Cooper-Schrieffer theory to those of strongly bound molecules undergoing Bose-Einstein condensation. First, we focus on the finite-temperature Equation of State (EoS) of the unpolarized unitary gas. Surprisingly, the low-temperature properties of the strongly interacting normal phase are well described by Fermi liquid theory [3] and we localize the superfluid phase transition. A detailed comparison with theories including recent Monte-Carlo calculations will be presented. Moving away from the unitary gas, the Lee-Huang-Yang and Lee-Yang beyond-mean-field corrections for low density bosonic and fermionic superfluids are quantitatively measured for the first time. Despite orders of magnitude difference in density and temperature, our equation of state can be used to describe low density neutron matter such as the outer shell of neutron stars. [4pt] [1] S. Nascimbène, N. Navon, K. Jiang, F. Chevy, and C. Salomon, Nature 463, 1057 (2010) [0pt] [2] N. Navon, S. Nascimbène, F. Chevy, and C. Salomon, Science 328, 729 (2010) [0pt] [3] S. Nascimbène, N. Navon, S. Pilati, F. Chevy, S. Giorgini, A. Georges, and C. Salomon, Phys. Rev. Lett. 106, 215303 (2011)

  5. Electrochemical sensor monitoring of volcanic gases

    NASA Astrophysics Data System (ADS)

    Roberts, Tjarda; Freshwater, Ray; Oppenheimer, Clive; Saffell, John; Jones, Rod; Griffiths, Paul; Braban, Christine; Mead, Iqbal

    2010-05-01

    Advances in instrumentation have fuelled a recent growth of interest in using portable sensor systems for environmental monitoring of pollution. Developments in wireless technology are enabling such systems to operate remotely and autonomously, generating a wealth of environmental data. We report here on the application of miniature Alphasense electrochemical sensors to the detection and characterisation of gases in volcanic plumes. A highly portable sensor system was developed to operate an array of 6 low cost electrochemical sensors to detect CO, H2, HCl, SO2, H2S and NO2 at 1 Hz. A miniature pump draws air over all sensors simultaneously (i.e. sensors arranged in parallel). The sensor output in these campaigns was logged on PDAs for real-time viewing, and later download (with a view to future data-streaming). The instrument was deployed at a number of volcanoes and was subject to extremely harsh conditions including highly acidic environments, low (Antarctic) temperatures, and transport over rough terrain. Analysis methods are demonstrated that consider calibration, cross-sensitivities of the sensors to multiple gases, differing sensor response times, temperature dependence, and background sensor drift with time. The analysis is applied to a range of plume field-measurements to extract gas concentrations ranging from 100's ppmv to sub-ppmv and to characterise the individual volcano emissions. Applications of similar sensor systems for real-time long-term monitoring of volcanic emissions (which may indicate and ultimately predict eruptive behavior), and UAV and balloon-borne plume sampling are now already being realised. This work focused on demonstrating the application of electrochemical sensors to monitoring of environmental pollution from volcanoes. Other applications for similar sensors include the near-source monitoring of industrial emissions, and of pollutant levels enhanced by traffic emissions in the urban environment.

  6. Potential effects of anthropogenic greenhouse gases on avian habitats and populations in the northern Great Plains

    USGS Publications Warehouse

    Larson, D.L.

    1994-01-01

    Biotic response to the buildup of greenhouse gases in Earth's atmosphere is considerably more complex than an adjustment to changing temperature and precipitation. The fertilization effect carbon dioxide has on some plants, the impact UVB radiation has on health and productivity of organisms, and the resulting changes in competitive balance and trophic structure must also be considered. The intent of this paper is to review direct and indirect effects of anthropogenic greenhouse gases on wildlife, and to explore possible effects on populations of birds and their habitats in the northern Great Plains.Many of the potential effects of increasing greenhouse gases, such as declining plant nutritional value, changes in timing of insect emergence, and fewer and saltier wetlands, foreshadow a decline in avian populations on the Great Plains. However, other possible effects such as increased drought resistance and water use efficiency of vegetation, longer growing seasons, and greater overall plant biomass promise at least some mitigation. Effects of multiple simultaneous perturbations such as can be expected under doubled carbon dioxide scenarios will require substantial basic research to clarify.

  7. Using biogenic sulfur gases as remotely detectable biosignatures on anoxic planets.

    PubMed

    Domagal-Goldman, Shawn D; Meadows, Victoria S; Claire, Mark W; Kasting, James F

    2011-06-01

    We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS(2), OCS, CH(3)SH, CH(3)SCH(3), and CH(3)S(2)CH(3)) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH(3)SCH(3), or DMS) and dimethyl disulfide (CH(3)S(2)CH(3), or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C(2)H(6)) over that which would be predicted based on the planet's methane (CH(4)) concentration. Thus, a characterization mission could detect these organic sulfur gases-and therefore the life that produces them-if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere. PMID:21663401

  8. Using Biogenic Sulfur Gases as Remotely Detectable Biosignatures on Anoxic Planets

    PubMed Central

    Meadows, Victoria S.; Claire, Mark W.; Kasting, James F.

    2011-01-01

    Abstract We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS2, OCS, CH3SH, CH3SCH3, and CH3S2CH3) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH3SCH3, or DMS) and dimethyl disulfide (CH3S2CH3, or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C2H6) over that which would be predicted based on the planet's methane (CH4) concentration. Thus, a characterization mission could detect these organic sulfur gases—and therefore the life that produces them—if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere. Key Words: Exoplanets—Biosignatures—Anoxic atmospheres—Planetary atmospheres—Remote life detection—Photochemistry. Astrobiology 11, 419–441. PMID:21663401

  9. Cloud-radiation interactions - Effects of cirrus optical thickness feedbacks

    NASA Technical Reports Server (NTRS)

    Somerville, Richard C. J.; Iacobellis, Sam

    1987-01-01

    The paper is concerned with a cloud-radiation feedback mechanism which may be an important component of the climate changes expected from increased atmospheric concentrations of carbon dioxide and other trace greenhouse gases. A major result of the study is that cirrus cloud optical thickness feedbacks may indeed tend to increase the surface warming due to trace gas increases. However, the positive feedback from cirrus appears to be generally weaker than the negative effects due to lower clouds. The results just confirm those of earlier research indicating that the net effect of cloud optical thickness feedbacks may be a negative feedback which may substantially (by a factor of about 2) reduce the surface warming due to the doubling of CO2, even in the presence of cirrus clouds.

  10. Measurements of Trace Gases in the Tropical Tropopause Layer

    NASA Technical Reports Server (NTRS)

    Marcy, T. P.; Popp, P. J.; Gao, R. S.; Fahey, D. W.; Ray, E. A.; Richard, E. C.; Thompson, T. L.; Atlas, E. L.; Lowenstein, M.; Wofsy, S. C.; Park, S.; Weinstock, E. M.; Swartz, W. H.; Mahoney, M. J.

    2008-01-01

    A unique dataset of airborne in situ observations of HCl, O3, HNO3, H2O, CO, CO2 and CH3Cl has been made in and near the tropical tropopause layer (TTL). A total of 16 profiles across the tropopause were obtained at latitudes between 10degN and 3degs from the NASA WB-57F high-altitude aircraft flying from Costa Rica. Few in situ measurements of these gases, particularly HCl and HNO3, have been reported for the TTL. The general features of the trace gas vertical profiles are consistent with the concept of the TTL as distinct from the lower troposphere and lower stratosphere. A combination of the tracer profiles and correlations with O3 is used to show that a measurable amount of stratospheric air is mixed into this region. The HCl measurements offer an important constraint on stratospheric mixing into the TTL because once the contribution from halocarbon decomposition is quantified, the remaining HCl (>60% in this study) must have a stratospheric source. Stratospheric HCl in the TTL brings with it a proportional amount of stratospheric O3. Quantifying the sources of O3 in the TTL is important because O3 is particularly effective as a greenhouse gas in the tropopause region.

  11. Quantum oscillations in ultracold Fermi gases : realizations with rotating gases or artificial gauge fields

    E-print Network

    Charles Grenier; Corinna Kollath; Antoine Georges

    2012-12-26

    We consider the angular momentum of a harmonically trapped, noninteracting Fermi gas subject to either rotation or to an artificial gauge field. The angular momentum of the gas is shown to display oscillations as a function of the particle number or chemical potential. This phenomenon is analogous to the de Haas - van Alphen oscillations of the magnetization in the solid-state context. However, key differences exist between the solid-state and ultracold atomic gases that we point out and analyze. We explore the dependence of the visibility of these oscillations on the physical parameters and propose two experimental protocols for their observation. Due to the very strong dependence of the amplitude of the oscillations on temperature, we propose their use as a sensitive thermometer for Fermi gases in the low temperature regime.

  12. Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases Fiscal Year 2001 Annual Report

    SciTech Connect

    Cushman, R.M.

    2002-10-15

    The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has, since its inception in 1982, enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change, including concentrations of carbon dioxide (CO{sub 2}) and other radiatively active gases in the atmosphere; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; emissions of CO{sub 2} and other trace gases to the atmosphere; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea levels. CDIAC is located within the Environmental Sciences Division (ESD) at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. CDIAC is co-located with ESD researchers investigating global-change topics, such as the global carbon cycle and the effects of carbon dioxide on climate and vegetation. CDIAC staff are also connected with current ORNL research on related topics, such as renewable energy and supercomputing technologies. CDIAC is supported by the Environmental Sciences Division (Jerry Elwood, Director) of DOE's Office of Biological and Environmental Research. CDIAC represents DOE in the multi-agency Global Change Data and Information System (GCDIS). Wanda Ferrell is DOE's Program Manager with overall responsibility for CDIAC. Roger Dahlman is responsible for CDIAC's AmeriFlux tasks, and Anna Palmisano for CDIAC's Ocean Data tasks. CDIAC is made up of three groups: Data Systems, Information Services, and Computer Systems, with nineteen full-time or part-time staff. The following section provides details on CDIAC's staff and organization. The Data Systems Group identifies and obtains databases important to global-change research; analyzes data; compiles needed databases; provides data management and support to specific programs [e.g., NARSTO, Free-Air CO{sub 2} Enrichment (FACE), AmeriFlux, Oceans]; and prepares documentation to ensure the long-term utility of CDIAC's data holdings. The Information Services Group responds to data and information requests; maintains records of all request activities; analyzes user statistics; assists in Web development and maintenance; and produces CDIAC's newsletter (CDIAC Communications), the fiscal year annual reports, and various information materials. The Computer Systems Group provides computer system support for all CDIAC and WDC activities; designs and maintains CDIAC's computing system network; ensures compliance with ORNL/DOE computing security regulations; ensures long-term preservation of CDIAC data holdings through systematic backups; evaluates, develops, and implements software; ensures standards compliance; generates user statistics; provides Web design, development, and oversight; and provides systems analysis and programming assistance for scientific data projects.

  13. Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases Fiscal Year 1999 Annual Report

    SciTech Connect

    Cushman, R.M.

    2000-03-31

    The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global-change data and information analysis center of the Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has--since its inception in 1982--enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change, including concentrations of carbon dioxide (CO{sub 2}) and other radiatively active gases in the atmosphere; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; emissions of CO{sub 2} and other trace gases to the atmosphere; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea level. CDIAC is located within the Environmental Sciences Division (ESD) at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. CDIAC is co-located with ESD researchers investigating global-change topics, such as the global carbon cycle and the effects of carbon dioxide on vegetation. CDIAC staff are also connected with current ORNL research on related topics, such as renewable energy and supercomputing technologies. CDIAC is supported by the Environmental Sciences Division (Jerry Elwood, Acting Director) of DOE's Office of Biological and Environmental Research. CDIAC's FY 1999 budget was 2.2M dollars. CDIAC represents the DOE in the multi-agency Global Change Data and Information System. Bobbi Parra, and Wanda Ferrell on an interim basis, is DOE's Program Manager with responsibility for CDIAC. CDIAC comprises three groups, Global Change Data, Computer Systems, and Information Services, with seventeen full-time and part-time staff. The Global Change Data group is responsible for identifying and obtaining databases important to global-change research, analyzing data, compiling needed databases, providing data management support to specific programs (e.g., NARSTO), and preparing documentation to ensure the long-term utility of CDIAC's data holdings. The Computer Systems group provides computer system support for all CDIAC and WDC activities, including designing and maintaining CDIAC's computing system network; ensuring compliance with ORNL/DOE computing security regulations; ensuring long-term preservation of CDIAC data holdings through systematic backups; evaluating, developing, and implementing software; ensuring standards compliance; generating user statistics; providing Web design, development, and oversight; and providing systems analysis and programming assistance for scientific data projects. The Information Services group responds to data and information requests; maintains records of all request activities; assists in Web development and maintenance; and produces CDIAC's newsletter, CDIAC Communications, catalog, glossary, and educational materials. The following section provides further details on CDIAC's organization.

  14. POLLUTANT EMISSIONS FROM 'DIRTY' LOW- AND MEDIUM-BTU GASES

    EPA Science Inventory

    The report gives results of a study to determine the emissions from 'dirty' low- and medium-Btu gases when combusted on industrial process burners. The fuels tested were blends with compositions typical of Wellman-Galusha oxygen (WGO) and air (WGA) fuel gases. Baseline data were ...

  15. 49 CFR 229.43 - Exhaust and battery gases.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Exhaust and battery gases. 229.43 Section 229.43... § 229.43 Exhaust and battery gases. (a) Products of combustion shall be released entirely outside the cab and other compartments. Exhaust stacks shall be of sufficient height or other means provided...

  16. Method of converting environmentally pollutant waste gases to methanol

    SciTech Connect

    Pfingstl, H.; Martyniuk, W.; Hennepin, A. Ill; McNally, T.; Myers, R.; Eberle, L.

    1993-08-03

    A continuous flow method is described of converting environmentally pollutant by-product gases emitted during the manufacture of silicon carbide to methanol comprising: (a) operating a plurality of batch furnaces of a silicon carbide manufacturing plant thereby producing silicon carbide and emitting by-product gases during the operation of the furnaces; (b) staggering the operation of the batch furnaces to achieve a continuous emission of the by-product gases; (c) continuously flowing the by-product gases as emitted from the batch furnaces directly to a methanol manufacturing plant; (d) cleansing the by-product gases of particulate matter, including removing the element sulfur from the by-product gases, as they are flowed to the methanol manufacturing plant, sufficiently for use of the by-product gases in producing methanol; and (e) immediately producing methanol from the by-product gases at the methanol manufacturing plant whereby the producing of silicon carbide is joined with the producing of methanol as a unified process.

  17. Sulfur Dioxide Treatment from Flue Gases Using a Biotrickling

    E-print Network

    Sulfur Dioxide Treatment from Flue Gases Using a Biotrickling Filter-Bioreactor System L I G Y P H of California, Riverside, California 92521 Complete treatment of sulfur dioxide (SO2) from flue gases in a two effectively treat the biotrickling filter effluent and produce elemental sulfur. The sulfur production

  18. A Simple Experiment to Demonstrate the Effects of Greenhouse Gases

    ERIC Educational Resources Information Center

    Keating, C. F.

    2007-01-01

    The role of greenhouse gases in our atmosphere is the subject of considerable discussion and debate. Global warming is well-documented, as is the continually increasing amount of greenhouse gases that human activity puts in the air. Is there a relationship between the two? The simple experiment described in this paper provides a good demonstration…

  19. Continuous cryopump with a method for removal of solidified gases

    DOEpatents

    Carlson, L.W.; Herman, H.

    1988-05-05

    An improved cryopump for the removal of gases from a high vacuum, comprising a cryopanel incorporating honeycomb structure, refrigerant means thermally connected to the cryopanel, and a rotatable channel moving azimuthally around an axis located near the center of the cryopanel, removing gases adsorbed within the honeycomb structure by subliming them and conducting them outside the vacuum vessel. 4 figs.

  20. Continuous cryopump with a method for removal of solidified gases

    DOEpatents

    Carlson, Larry W. (Oswego, IL); Herman, Harold (Park Forest, IL)

    1989-01-01

    An improved cryopump for the removal of gases from a high vacuum, comprising a cryopanel incorporating honeycomb structure, refrigerant means thermally connected to the cryopanel, and a rotatable channel moving azimuthally around an axis located near the center of the cryopanel, removing gases absorbed within the honeycomb structure by subliming them and conducting them outside the vacuum vessel.

  1. 49 CFR 229.43 - Exhaust and battery gases.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Exhaust and battery gases. 229.43 Section 229.43... § 229.43 Exhaust and battery gases. (a) Products of combustion shall be released entirely outside the... conditions. (b) Battery containers shall be vented and batteries kept from gassing excessively....

  2. 49 CFR 229.43 - Exhaust and battery gases.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Exhaust and battery gases. 229.43 Section 229.43... § 229.43 Exhaust and battery gases. (a) Products of combustion shall be released entirely outside the... conditions. (b) Battery containers shall be vented and batteries kept from gassing excessively....

  3. 49 CFR 229.43 - Exhaust and battery gases.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Exhaust and battery gases. 229.43 Section 229.43... § 229.43 Exhaust and battery gases. (a) Products of combustion shall be released entirely outside the... conditions. (b) Battery containers shall be vented and batteries kept from gassing excessively....

  4. 49 CFR 229.43 - Exhaust and battery gases.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Exhaust and battery gases. 229.43 Section 229.43... § 229.43 Exhaust and battery gases. (a) Products of combustion shall be released entirely outside the... conditions. (b) Battery containers shall be vented and batteries kept from gassing excessively....

  5. Temperature Dependence of Viscosities of Common Carrier Gases

    ERIC Educational Resources Information Center

    Sommers, Trent S.; Nahir, Tal M.

    2005-01-01

    Theoretical and experimental evidence for the dependence of viscosities of the real gases on temperature is described, suggesting that this dependence is greater than that predicted by the kinetic theory of gases. The experimental results were obtained using common modern instrumentation and could be reproduced by students in analytical or…

  6. Hazards of Volcanic Gases Glyn Williams-Jones

    E-print Network

    Williams-Jones, Glyn

    -related deaths between 1600 and 1982). The composition of volcanic gases depends on the type of volcano and its continuous products of volcanic activity. Even volcanoes in a state of quiescence, not actually erupting hazard. Although volcanic gases are only directly responsible for 1e4% of volcano-related deaths

  7. GLOBAL MITIGATION OF NON-CO2 GREENHOUSE GASES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mitigation of noncarbon dioxide (non-CO2) greenhouse gas emissions can be a relatively inexpensive supplement to CO2-only mitigation strategies. The non-CO2 gases include methane (CH4), nitrous oxide (N2O), and a number of high global warming potential (high- GWP) or fluorinated gases. These ga...

  8. 40 CFR 258.23 - Explosive gases control.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Explosive gases control. 258.23 Section 258.23 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.23 Explosive gases control. (a) Owners or operators of all MSWLF units must ensure...

  9. 40 CFR 258.23 - Explosive gases control.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Explosive gases control. 258.23 Section 258.23 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.23 Explosive gases control. (a) Owners or operators of all MSWLF units must ensure...

  10. Single particle density of trapped interacting quantum gases

    SciTech Connect

    Bala, Renu; Bosse, J.; Pathak, K. N.

    2015-05-15

    An expression for single particle density for trapped interacting gases has been obtained in first order of interaction using Green’s function method. Results are easily simplified for homogeneous quantum gases and are found to agree with famous results obtained by Huang-Yang-Luttinger and Lee-Yang.

  11. Fullerenes and Noble Gases in the Murchison and Allende Meteorites

    NASA Technical Reports Server (NTRS)

    Becker, Luann; Poreda, Robert J.; Bunch, Ted E.

    2000-01-01

    In this work we report the detection of fullerenes (C60 to C250) in the Murchison and Allende meteorites. By exploiting the unique ability of these molecules to trap noble gases, we have determined that fullerene is indeed a new carrier phase for noble gases in meteorites.

  12. 30 CFR 75.322 - Harmful quantities of noxious gases.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Harmful quantities of noxious gases. 75.322 Section 75.322 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.322 Harmful quantities of noxious gases. Concentrations of...

  13. 30 CFR 75.322 - Harmful quantities of noxious gases.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Harmful quantities of noxious gases. 75.322 Section 75.322 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.322 Harmful quantities of noxious gases. Concentrations of...

  14. 30 CFR 75.322 - Harmful quantities of noxious gases.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Harmful quantities of noxious gases. 75.322 Section 75.322 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.322 Harmful quantities of noxious gases. Concentrations of...

  15. 30 CFR 75.322 - Harmful quantities of noxious gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Harmful quantities of noxious gases. 75.322 Section 75.322 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.322 Harmful quantities of noxious gases. Concentrations of...

  16. 76 FR 47391 - Mandatory Reporting of Greenhouse Gases

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-04

    ...Division, Office of Atmospheric Programs (MC-6207J...please go to the Greenhouse Gas Reporting Rule...substantial direct effects on the States...that directly emit greenhouses gases...or environmental effects on minority or...and procedure, Greenhouse gases,...

  17. 75 FR 57669 - Mandatory Reporting of Greenhouse Gases

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-22

    ...Mandatory Reporting of Greenhouse Gases from Magnesium...insights on the potential effects. This analysis is...before a rule may take effect, the agency promulgating...major rule cannot take effect until 60 days after...practice and procedure, Greenhouse gases,...

  18. Radiation enteritis

    MedlinePLUS

    Radiation enteropathy; Radiation-induced small bowel injury; Post-radiation enteritis ... Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells. The therapy ...

  19. Radiation Therapy

    MedlinePLUS

    ... Professionals Questions to Ask about Your Treatment Research Radiation Therapy Radiation therapy (also called radiotherapy) is a ... rays of your teeth or broken bones. How Radiation Therapy Works against Cancer At high doses, radiation ...

  20. Problem of nature of inert gases in lunar surface material

    NASA Technical Reports Server (NTRS)

    Levskiy, L. K.

    1974-01-01

    The origin of isotopes of inert gases in lunar surface material was investigated from the standpoint of the isotopic two-component status of inert gases in the solar system. Helium and neon represent the solar wind component, while krypton and xenon are planetary gases. Type A gases are trapped by the material of the regolith in the early stages of the existence of the solar system and were brought to the lunar surface together with dust. The material of the regolith therefore cannot be considered as the product of the erosion of the crystalline rocks of the moon and in this sense are extralunar. The regolith material containing type A gases must be identified with the high temperature minerals of the carbonaceous chondrites.

  1. IUPAC-NIST Solubility Data Series 70. The Solubility of Gases in Glassy Polymers

    NASA Astrophysics Data System (ADS)

    Paterson, Russell; Yampol'Skii, Yuri P.; Fogg, Peter G. T.; Bokarev, Alexandre; Bondar, Valerii; Ilinich, Oleg; Shishatskii, Sergey

    1999-09-01

    Solubility of gases in polymers is an important property of polymeric materials relevant to many practical applications. Sorption of small molecules in polymers is a fundamental concern in such areas as food packaging, beverage storage, and polymer processing. However, by far the main interest in the solubility of gases in polymers, and especially in glassy polymers, is related to development of novel advanced materials for gas separation membranes. This is because the concentration gradient of a dissolved gas is the driving force of membrane processes. Development of these novel separation methods resulted in a rapid accumulation, in the recent literature, of thermodynamic data related to the solubility of gases in polymers at different temperatures and pressures. Polymers can be regarded as special cases of media intermediate between liquids and solids. As a consequence, modeling of gas sorption in polymers is very difficult and presents a permanent challenge to theoreticians and experimenters. The collection and critical evaluation of solubility data for various gas-polymer systems is relevant to both practical aspects of polymer applications and to fundamental studies of polymer behavior. This volume of the IUPAC-NIST Solubility Data Series summarizes the compilations and critical evaluations of the data on solubility of gases in glassy polymers. It is implied in this edition that "gases" are the components that are either permanent gases (supercitical fluids) or have saturated vapor pressure more than 1 atm at ambient conditions (298 K). The polymeric components of compilations and critical evaluations are primarily high molecular mass, amorphous, linear (noncross-linked) compounds that have the glass transition temperatures above ambient temperature. The data for each gas-polymer system have been evaluated, if the results of at least three independent and reliable studies have been reported. Where the data of sufficient accuracy and reliability are available, values are recommended, and in some cases smoothing equations are given to represent variations of solubility with changes in gas pressure and temperature. Referenced works are presented in the standard IUPAC-NIST Solubility Data Series format. Depending on the gas-polymer system, reported data are given in tabular form or in the form of sorption isotherms. The data included in the volume comprise solubilities of 30 different gases in more than 80 primarily amorphous homo and copolymers. Where available, the compilation or critical evaluation sheets include enthalpies of sorption and parameters for sorption isotherms. Throughout the volume, SI conventions have been employed as the customary units in addition to the units used in original publications.

  2. Radiative Effects of Aerosols Generated from Biomass Burning, Dust Storms, and Forest Fires

    NASA Technical Reports Server (NTRS)

    Christopher Sundar A.; Vulcan, Donna V.; Welch, Ronald M.

    1996-01-01

    Atmospheric aerosol particles, both natural and anthropogenic, are important to the earth's radiative balance. They scatter the incoming solar radiation and modify the shortwave reflective properties of clouds by acting as Cloud Condensation Nuclei (CCN). Although it has been recognized that aerosols exert a net cooling influence on climate (Twomey et al. 1984), this effect has received much less attention than the radiative forcings due to clouds and greenhouse gases. The radiative forcing due to aerosols is comparable in magnitude to current anthropogenic greenhouse gas forcing but opposite in sign (Houghton et al. 1990). Atmospheric aerosol particles generated from biomass burning, dust storms and forest fires are important regional climatic variables. A recent study by Penner et al. (1992) proposed that smoke particles from biomass burning may have a significant impact on the global radiation balance. They estimate that about 114 Tg of smoke is produced per year in the tropics through biomass burning. The direct and indirect effects of smoke aerosol due to biomass burning could add up globally to a cooling effect as large as 2 W/sq m. Ackerman and Chung (1992) used model calculations and the Earth Radiation Budget Experiment (ERBE) data to show that in comparison to clear days, the heavy dust loading over the Saudi Arabian peninsula can change the Top of the Atmosphere (TOA) clear sky shortwave and longwave radiant exitance by 40-90 W/sq m and 5-20 W/sq m, respectively. Large particle concentrations produced from these types of events often are found with optical thicknesses greater than one. These aerosol particles are transported across considerable distances from the source (Fraser et al. 1984). and they could perturb the radiative balance significantly. In this study, the regional radiative effects of aerosols produced from biomass burning, dust storms and forest fires are examined using the Advanced Very High Resolution Radiometer (AVHRR) Local Area Coverage (LAC) data and the instantaneous scanner ERBE data from the NOAA-9 and NOAA-10 satellites.

  3. Generation of intense continuum extreme-ultraviolet radiation by many-cycle

    E-print Network

    Loss, Daniel

    LETTERS Generation of intense continuum extreme-ultraviolet radiation by many-cycle laser fields P radiation--with either gas or solid-surface targets12 --offer exciting opportunities for multiphoton extreme-ultraviolet on the synthesis of a continuum extreme-ultraviolet radiation emitted, so far, by rare gases driven by few

  4. Long term changes in the ionosphere over Indian low latitudes: Impact of greenhouse gases

    NASA Astrophysics Data System (ADS)

    Sharma, Som; Chandra, H.; Beig, G.

    2015-06-01

    Increased concentration of greenhouse gases due to anthropogenic activities warm the troposphere and have a cooling effect in the middle and upper atmosphere. Ionospheric densities and heights are affected due to cooling. Carbon dioxide is one of the most dominant gases for the cause of long term ionospheric trends along with other radiatively active greenhouse gases. Regular ionospheric soundings are made over Ahmedabad (23.1°N, 72.7°E), since 1953. Long term changes in the ionosphere as a consequence of the cooling of the mesosphere and thermosphere due to the increased concentration of greenhouse gases have been studied. Ionospheric observations over Ahmedabad, a low latitude station in the anomaly crest region, for the years 1955-2003 are examined to study the long term changes in the critical frequencies of the various ionospheric layers and the height of the maximum ionization as characterized by hPF2. A decrease in foF2 (1.9 MHz for midday, 1.4 MHz for midnight) and hPF2 (18 km for midday, 17 km for midnight) during about five decades are noted. An increase is noted in foF1 (0.4 MHz). The foF2 data are also examined over an equatorial station Kodaikanal (10.2°N, 77.5°E), situated near the magnetic equator for the years 1960-1995 and a decrease of 0.5 MHz for midday and 0.7 MHz for midnight are noted in ~35 years.

  5. Zevenhoven & Kilpinen Greenhouse Gases, Ozone-Depleting Gases 19.6.2001 9-1 Figure 9.1 Increasing world population

    E-print Network

    Zevenhoven, Ron

    over the arctic and antarctic poles. The ozone-layer is crucial for many forms of life on earthZevenhoven & Kilpinen Greenhouse Gases, Ozone-Depleting Gases 19.6.2001 9-1 Figure 9.1 Increasing Greenhouse gases, ozone-depleting gases 9.1 Introduction By the end of the 20th century it was widely

  6. Radiation curing of epoxies

    NASA Astrophysics Data System (ADS)

    Dickson, Lawrence W.; Singh, Ajit

    The literature on radiation polymerization of epoxy compounds has been reviewed to assess the potential use of radiation for curing these industrially important monomers. Chemical curing of epoxies may proceed by either cationic or anionic mechanisms depending on the nature of the curing agent, but most epoxies polymerize by cationic mechanisms under the influence of high-energy radiation. Radiation-induced cationic polymerization of epoxy compounds is inhibited by trace quantities of water because of proton transfer from the chain-propagating epoxy cation to water. Several different methods with potential for obtaining high molecular weight polymers by curing epoxies with high-energy radiation have been studied. Polymeric products with epoxy-like properties have been produced by radiation curing of epoxy oligomers with terminal acrylate groups and mixtures of epoxies with vinyl monomers. Both of these types of resin have good potential for industrial-scale curing by radiation treatment.

  7. Interactions of Hydrazine and Blowby Gases

    NASA Technical Reports Server (NTRS)

    Meagher, Nancy E.

    2003-01-01

    The interactions between hydrazine and blowby gases from pyrovalves was explored in this research project. Investigating the decomposition chemistry of hydrazine through detailed chemical kinetic modeling is a project started last summer while participating in the Summer Faculty Fellowship program. During the 1999-2000 academic year, the chemical kinetic mechanism for hydrazine decomposition developed while a SFF at NASA's White Sands Test Facility was further revised and validated against the limited experimental data in the literature. This mechanism was then used in assessing the effects of blowby gas species on hydrazine decomposition. The combustion products introduced into the fuel line by pyrovalve actuation consist primarily of hydrogen gas. Hydrogen is also a product of the decomposition of hydrazine. Additional gaseous chemical species are introduced into the fuel, as well as metals and metal salts that deposit onto the walls of the fuel line. The deposition process is undoubtedly very rapid, and exothermic. Therefore, the major focus of this summer's work was examining the effects of hydrogen presence on hydrazine decomposition, with some representative calculations including the remaining gaseous species found to exist in blowby gases. Since hydrogen is a product of hydrazine decomposition, all reactions necessary to evaluate its effect on hydrazine decomposition chemistry were in the original mechanism developed. However, the mechanism needed to be considerably expanded to include the reactions of the other gaseous blowby species with hydrazine, all the intermediate species formed in its decomposition, and each other. The expanded mechanism consists of 70 species interacting via a network of 452 reactions. Calculations with molecular hydrogen introduced into hydrazine gas in an inert bath gas indicate that H2 presence as an initial reactant in substantial amounts can dramatically impact the decomposition process for hydrazine. The other gaseous blowby species (CO, CO2, H2O, CH4, O2, and N2) were found to have little effect compared to the inclusion of hydrogen itself as an initial reagent. This result is undoubtedly due, in part, to the fact that the blowby gas used in these calculations consisted of 94.6% H2. A more rigorous examination of the behavior of the full detailed mechanism under a variety of conditions was not performed.

  8. Titan's South Pole Evolution in trace gases

    NASA Astrophysics Data System (ADS)

    Coustenis, Athena; Jennings, Donald; Achterberg, Richard; Bampasidis, Georgios; Lavvas, Panayiotis; Nixon, Conor; Teanby, Nick; Anderson, Carrie; Flasar, F. Michael

    2015-04-01

    Up until mid 2012, Titan's Northern atmosphere exhibited the enriched chemical compounds found at the time of Northern Spring Equinox (NSE) since the Voyager days (November 1980), with a peak around the NSE in 2009 [1,2]. Since then, a reversal in the abundances of some species from north to south has been observed with the appearance for the first time at Titan's south pole of some species such as HC3N at 663 cm-1 and C6H6 in large quantities. These species had previously been clearly observed only at high northern latitudes. Though not present in the south until February 2012, the 663 cm-1 emission appeared in CIRS spectra recorded on 24 July 2012 next to the CO2 band at 667 cm-1 and has been increasing since then. This is another strong indication of the buildup of the gaseous inventory in the southern stratosphere, as expected as the pole moves deeper into winter shadow. Downwelling nitrile gases that accumulate in the absence of ultraviolet sunlight, evidently increased quickly during 2012 and may be responsible also for the reported haze decrease in the north and its appearance in the south from its 220 cm-1 feature [3,4]. We present analysis for temperature and composition of the trace gases in Titan's stratosphere until late 2014. HC3N has increased by 2 orders of magnitude in the south over the past 2 years, while decreasing rapidly in the north. We find other interesting, although weaker transitions, from north to south for other molecules and we will discuss HCN, C3H4 and C4H2, which need to be monitored more in the future. References [1] Bampasidis et al., ApJ 760, 144, 8 p., 2012. [2] Coustenis, A., et al., Icarus, 207, 461-476, 2010. [3] Jennings, D. E., Anderson, C. M., Samuelson, R. E., et al. 2012a, ApJ, 754, L3 [4] Jennings, D. E., Anderson, C. M., Samuelson, R. E., et al. 2012b, ApJ 761, L15

  9. A Group Increment Scheme for Infrared Absorption Intensities of Greenhouse Gases

    NASA Technical Reports Server (NTRS)

    Kokkila, Sara I.; Bera, Partha P.; Francisco, Joseph S.; Lee, Timothy J.

    2012-01-01

    A molecule's absorption in the atmospheric infrared (IR) window (IRW) is an indicator of its efficiency as a greenhouse gas. A model for estimating the absorption of a fluorinated molecule within the IRW was developed to assess its radiative impact. This model will be useful in comparing different hydrofluorocarbons and hydrofluoroethers contribution to global warming. The absorption of radiation by greenhouse gases, in particular hydrofluoroethers and hydrofluorocarbons, was investigated using ab initio quantum mechanical methods. Least squares regression techniques were used to create a model based on this data. The placement and number of fluorines in the molecule were found to affect the absorption in the IR window and were incorporated into the model. Several group increment models are discussed. An additive model based on one-carbon groups is found to work satisfactorily in predicting the ab initio calculated vibrational intensities.

  10. Decoherence mechanisms of Landau level THz excitations in two dimensional electron gases

    SciTech Connect

    Maissen, Curdin; Scalari, Giacomo; Faist, Jérôme; Reichl, Christian; Wegscheider, Werner

    2013-12-04

    We report coherent THz transmission measurements on different two dimensional electron gases (2DEGs) in magnetic field. The investigated 2DEGs form in GaAs/AlGaAs heterostructures. A short (1 ps) linearly polarized THz pulse is used to excite inter Landau level transitions. The circular polarized radiation emitted by the 2DEG is then measured by electro optic sampling of the linear component orthogonal to the pump pulse polarization. Here we present measurements on two high mobility samples with ? = 5×10{sup 6}cm{sup 2}/Vs and ? = 16×10{sup 6}cm{sup 2}/Vs respectively. The decay times of the emitted radiation are 5.5 ps and 9 ps respectively at 2 K.

  11. Mid-Infrared OPO for High Resolution Measurements of Trace Gases in the Mars Atmosphere

    NASA Technical Reports Server (NTRS)

    Yu, Anthony W.; Numata,Kenji; Riris, haris; Abshire, James B.; Allan, Graham; Sun, Xiaoli; Krainak, Michael A.

    2008-01-01

    The Martian atmosphere is composed primarily (>95%) of CO2 and N2 gas, with CO, O2, CH4, and inert gases such as argon comprising most of the remainder. It is surprisingly dynamic with various processes driving changes in the distribution of CO2, dust, haze, clouds and water vapor on global scales in the meteorology of Mars atmosphere [I]. The trace gases and isotopic ratios in the atmosphere offer important but subtle clues as to the origins of the planet's atmosphere, hydrology, geology, and potential for biology. In the search for life on Mars, an important process is the ability of bacteria to metabolize inorganic substrates (H2, CO2 and rock) to derive energy and produce methane as a by-product of anaerobic metabolism. Trace gases have been measured in the Mars atmosphere from Earth, Mars orbit, and from the Mars surface. The concentration of water vapor and various carbon-based trace gases are observed in variable concentrations. Within the past decade multiple groups have reported detection of CH4, with concentrations in the 10's of ppb, using spectroscopic observations from Earth [2]. Passive spectrometers in the mid-infrared (MIR) are restricted to the sunlit side of the planet, generally in the mid latitudes, and have limited spectral and spatial resolution. To accurately map the global distribution and to locate areas of possibly higher concentrations of these gases such as plumes or vents requires an instrument with high sensitivity and fine spatial resolution that also has global coverage and can measure during both day and night. Our development goal is a new MIR lidar capable of measuring, on global scales, with sensitivity, resolution and precision needed to characterize the trace gases and isotopic ratios of the Martian atmosphere. An optical parametric oscillator operating in the MIR is well suited for this instrument. The sufficient wavelength tuning range of the OPO can extend the measurements to other organic molecules, CO2, atmospheric water vapor, clouds, temperature, dust, and aerosols, as well as possibly polar-cap properties. Our OPO-approach may allow a new capability for active remote sensing of the outer planets and moons, where the weaker sunlight further limit passive instruments. Here we report on the OPO development effort for this lidar instrument.

  12. Radiative Magnetic Reconnection in Astrophysics

    E-print Network

    Uzdensky, Dmitri A

    2015-01-01

    I review a new rapidly growing area of high-energy plasma astrophysics --- radiative magnetic reconnection, i.e., a reconnection regime where radiation reaction influences reconnection dynamics, energetics, and nonthermal particle acceleration. This influence be may be manifested via a number of astrophysically important radiative effects, such as radiation-reaction limits on particle acceleration, radiative cooling, radiative resistivity, braking of reconnection outflows by radiation drag, radiation pressure, viscosity, and even pair creation at highest energy densities. Self-consistent inclusion of these effects in magnetic reconnection theory and modeling calls for serious modifications to our overall theoretical approach to the problem. In addition, prompt reconnection-powered radiation often represents our only observational diagnostic tool for studying remote astrophysical systems; this underscores the importance of developing predictive modeling capabilities to connect the underlying physical condition...

  13. Mechanism of Radiation-Induced Doping

    NASA Astrophysics Data System (ADS)

    Koizumi, Hitoshi; Dougauchi, Hiroshi; Yamano, Tadaomi; Ichikawa, Tsuneki

    2003-11-01

    Poly(3-octylthiophene) was irradiated with X-rays in atmospheres of CH3Br, SF6, and N2O gases. The electrical conductivity was increased after the irradiations. The electrical conductivity was also increased by irradiating the gases near the polymer film without irradiating the film itself. This result indicates that dopants were generated upon irradiation in the gas phase and the polymer was doped through reactions of the dopants with the polymer. The radiation-induced doping effects were also observed for poly(3-octylthiophene) coated with solid 1,2,5,6,9,10-hexabromocyclododecane.

  14. Emission inventory for greenhouse gases in the City of Barcelona, 1987-1996

    NASA Astrophysics Data System (ADS)

    Baldasano, José M.; Soriano, Cecilia; Boada, Lluís.

    Emissions of greenhouse gases for the City of Barcelona are estimated for the period 1987-1994. The sources considered are: public and private transportation; industrial, commercial and domestic activities; and municipal solid waste disposal. The results show that the main source of CO 2 emissions in Barcelona is private vehicle transportation, which accounts, as an average for the period studied, for 35% of total emissions. The second most important source is the municipal solid waste landfill facility of the city (24% of total emissions). The percentages for the remaining sources under consideration were: 14% electricity, 12% natural gas, 5% incineration, and 3% liquefied petroleum gases. However, the values for CO 2 emissions per inhabitant over the period studied are lower than those for any other industrialized city available for comparison. This is closely related to the high percentage of electricity generation from nuclear power stations and hydro power facilities, and also to the extensive use of natural gas for domestic uses.

  15. A comprehensive study of different gases in inductively coupled plasma torch operating at one atmosphere

    SciTech Connect

    Punjabi, Sangeeta B.; Joshi, N. K.; Mangalvedekar, H. A.; Lande, B. K.; Das, A. K.; Kothari, D. C.

    2012-01-15

    A numerical study is done to understand the possible operating regimes of RF-ICP torch (3 MHz, 50 kW) using different gases for plasma formation at atmospheric pressure. A two dimensional numerical simulation of RF-ICP torch using argon, nitrogen, oxygen, and air as plasma gas has been investigated using computational fluid dynamic (CFD) software fluent{sup (c)}. The operating parameters varied here are central gas flow, sheath gas flow, RF-power dissipated in plasma, and plasma gas. The temperature contours, flow field, axial, and radial velocity profiles were investigated under different operating conditions. The plasma resistance, inductance of the torch, and the heat distribution for various plasma gases have also been investigated. The plasma impedance of ICP torch varies with different operating parameters and plays an important role for RF oscillator design and power coupling. These studies will be useful to decide the design criteria for ICP torches required for different material processing applications.

  16. Spectral response of magnetically trapped Bose gases to weak microwave fields

    NASA Astrophysics Data System (ADS)

    Federsel, P.; Rogulj, C.; Menold, T.; Fortágh, J.; Günther, A.

    2015-09-01

    Microwave fields can be used to drive local spin transitions in quantum gases and for outcoupling of cold atomic beams from magnetic traps. In this paper, we derive an analytic theory for the outcoupling rate as a response to weak microwave fields of varying frequency and power. The theory holds for thermal clouds and Bose-Einstein condensates. It allows for calculating transition rates in arbitrary magnetic trap geometries and includes the effect of gravity. We verify our theory by measuring the flux of outcoupled atoms at the single-particle level. The derived spectral response is important for magnetic noise spectroscopy with quantum gases, and for probing quantum gas dynamics with single atom detectors in real time.

  17. A comprehensive study of different gases in inductively coupled plasma torch operating at one atmosphere

    NASA Astrophysics Data System (ADS)

    Punjabi, Sangeeta B.; Joshi, N. K.; Mangalvedekar, H. A.; Lande, B. K.; Das, A. K.; Kothari, D. C.

    2012-01-01

    A numerical study is done to understand the possible operating regimes of RF-ICP torch (3 MHz, 50 kW) using different gases for plasma formation at atmospheric pressure. A two dimensional numerical simulation of RF-ICP torch using argon, nitrogen, oxygen, and air as plasma gas has been investigated using computational fluid dynamic (CFD) software fluent©. The operating parameters varied here are central gas flow, sheath gas flow, RF-power dissipated in plasma, and plasma gas. The temperature contours, flow field, axial, and radial velocity profiles were investigated under different operating conditions. The plasma resistance, inductance of the torch, and the heat distribution for various plasma gases have also been investigated. The plasma impedance of ICP torch varies with different operating parameters and plays an important role for RF oscillator design and power coupling. These studies will be useful to decide the design criteria for ICP torches required for different material processing applications.

  18. Methane activation using noble gases in a dielectric barrier discharge reactor

    SciTech Connect

    Jo, Sungkwon; Hoon Lee, Dae; Seok Kang, Woo; Song, Young-Hoon

    2013-08-15

    The conversion of methane is measured in a planar-type dielectric barrier discharge reactor using three different noble gases—He, Ne, and Ar—as additives. The empirical results obtained clearly indicate that methane activation is considerably affected by thy type of noble gas used. Through 0-D calculations, the discharge parameters inside the reactor, i.e., electron temperature and electron density, are estimated using experiment results. A comparison of the discharge characteristics and experimental results shows that the electron temperature is an important factor in achieving high methane activation and the mixture with Ar gas shows the highest methane conversion. These results are constructed using the mechanisms of energy and charge transfer from excited and ionized noble gas atoms to methane molecules, considering the number density of active atoms of noble gases. Finally, electron temperatures obtained for gas mixtures having different reactant compositions and concentrations are analyzed to estimate methane activation.

  19. Transfer-line heat exchanger fouling during pyrolysis of hydrocarbons. 1: Deposits from dry cracked gases

    SciTech Connect

    Bach, G.; Zimmermann, G.; Kopinke, F.D.; Barendregt, S.; Oosterkamp, P. van den; Woerde, H.

    1995-04-01

    Isobutane of technical quality was pyrolyzed in nitrogen as a diluent under standardized conditions (820 C, 0.4 s, N{sub 2}/isobutane = 0.4 g/g) in a specially developed, vertically positioned tubular flow reactor coupled with a micro electrobalance. After cooling the dry cracked gases to temperatures thought to be representative for the innertube surface temperatures of a TLE (transfer-line exchanger), the growth of carbon-rich deposits (known as TLE fouling) was measured continuously at the surfaces of material coupons in dependence on (1) the prehistory and (2) the sort of materials as well as (3) the temperatures. The results show clearly that on low alloyed steels catalytic reactions can play an important role in TLE fouling if dry cracked gases are used.

  20. Rubidium D1 collision shift by heavy noble gases

    NASA Astrophysics Data System (ADS)

    Wells, N. P.; Driskell, T. U.; Camparo, J. C.

    2015-10-01

    Using an isoclinic-point technique, we measured the D1 collision shift by Xe, ? [? ? ]/? P , and the exponent ? of the shift's temperature dependence (i.e., ? ? ˜T? ). As demonstrated in our examination of the Rb-Kr system [N. P. Wells et al., Phys. Rev. A 89, 052516 (2014), 10.1103/PhysRevA.89.052516], the isoclinic point provides (arguably) the only means of assessing ? unambiguously: ?Kr=0.36 ±0.06 and in the present work ?Xe=0.32 ±0.05 . With our estimate of ? for the Rb-Kr and Rb-Xe systems, we were able to combine our Kr and Xe collision shift measurements with those of Rotondaro and Perram [M. D. Rotondaro and G. P. Perram, J. Quant. Spectrosc. Radiat. Transfer 57, 497 (1997), 10.1016/S0022-4073(96)00147-1] (another set of high quality ? [? ? ]/? P measurements) to obtain a highly accurate experimental estimate for the D1 collision shift resulting from Rb's interaction with the heavy noble gases: For the Rb-Kr interaction ? [? ? ] /? P |T =323 K=-5.02 ±0.07 MHz /torr and for the Rb-Xe interaction ? [? ? ] /? P |T =323 K=-5.46 ±0.09 MHz /torr . These measured values for the collision-shift coefficient are approximately 20 % smaller (in magnitude) than the best theoretical estimates, suggesting that there is room for theoretical improvement regarding our present understanding of how noble-gas collisions perturb the alkali-metal P1 /2 state.

  1. Noble gases in Luna 24 core soils

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Hirsch, W. C.

    1978-01-01

    Isotopic abundances of the noble gases have been determined in grain size separates of six soils from different depths in the Luna 24 core. Concentrations of cosmogenic Ne-21 in these soils show a complex pattern as a function of soil depth, and are inconsistent with a single stage, in situ production in a static regolith or with a simple model of slow accumulation of previously unirradiated soils followed by a static period. All soils have apparently had a complex pre-irradiation history. Some soils show significant differences in the concentration of cosmogenic Ne-21 between different grain sizes, which is consistent with suggestions that they formed as a mixture of soils with different maturities. The exact subsurface depth relationships of the soils are not known, and several possibilities are discussed. Because of this factor and the complex nature of the soils, the cosmogenic Ne data do not define the depositional-irradiational history of the core. Luna 24 core soils may have been deposited any time during the past 300 million years.

  2. Producing Quantum Degenerate Gases of Strontium

    NASA Astrophysics Data System (ADS)

    Camargo, Francisco; Ding, Roger; Whalen, Joseph; Woehl, Germano; Dunning, Barry; Killian, Thomas

    2015-05-01

    We present our progress towards producing quantum degenerate gases of all four stable isotopes of strontium (84Sr, 86Sr, 87Sr, 88Sr) and isotopic mixtures. We characterize the performance of our broad-line (461 nm, 30.5 MHz), narrow-line (689 nm, 7.5 kHz) magneto-optical traps, and examine evaporative cooling for all four isotopes. The new apparatus will be used to create and study tunable long-range interactions by dressing with strongly-interacting Rydberg states. The ability to trap the four different isotopes allows a measure of control of these interactions through access to a range of attractive and repulsive interactions. Simultaneous trapping of different isotopes provides opportunities for novel laser cooling schemes for studying Bose-Bose and Bose-Fermi mixtures. Research supported by the AFOSR under grant no. FA9550-12-1-0267, the NSF under grants nos. 1301773 and 1205946, and the Robert A. Welch Foundation under grant no. C-0734.

  3. Measuring non-condensable gases in steam

    SciTech Connect

    Doornmalen, J. P. C. M. van; Kopinga, K.

    2013-11-15

    In surgery, medical devices that are used should be sterilized. To obtain surface steam sterilization conditions, not only in the sterilizer chamber itself but also in the loads to be sterilized, the amount of non-condensable gases (NCGs), for instance air, should be very low. Even rather small fractions of NCGs (below 1 %) seriously hamper steam penetration in porous materials or devices with hollow channels (e.g., endoscopes). A recently developed instrument which might detect the presence of residual NCGs in a reliable and reproducible way is the 3M{sup TM} Electronic Test System (ETS). In this paper, a physical model is presented that describes the behavior of this instrument. This model has been validated by experiments in which known fractions of NCGs were introduced in a sterilizer chamber in which an ETS was placed. Despite several approximations made in the model, a good agreement is found between the model predictions and the experimental results. The basic principle of the ETS, measuring the heat transfer by condensation on a cooled surface, permits a very sensitive detection of NCGs in harsh environments like water vapor at high temperatures and pressures. Our model may serve to develop adapted and optimized versions of this instrument for use outside the field of sterilization, e.g., in heat exchangers based on steam condensation.

  4. Measuring non-condensable gases in steam

    NASA Astrophysics Data System (ADS)

    van Doornmalen, J. P. C. M.; Kopinga, K.

    2013-11-01

    In surgery, medical devices that are used should be sterilized. To obtain surface steam sterilization conditions, not only in the sterilizer chamber itself but also in the loads to be sterilized, the amount of non-condensable gases (NCGs), for instance air, should be very low. Even rather small fractions of NCGs (below 1 %) seriously hamper steam penetration in porous materials or devices with hollow channels (e.g., endoscopes). A recently developed instrument which might detect the presence of residual NCGs in a reliable and reproducible way is the 3MTM Electronic Test System (ETS). In this paper, a physical model is presented that describes the behavior of this instrument. This model has been validated by experiments in which known fractions of NCGs were introduced in a sterilizer chamber in which an ETS was placed. Despite several approximations made in the model, a good agreement is found between the model predictions and the experimental results. The basic principle of the ETS, measuring the heat transfer by condensation on a cooled surface, permits a very sensitive detection of NCGs in harsh environments like water vapor at high temperatures and pressures. Our model may serve to develop adapted and optimized versions of this instrument for use outside the field of sterilization, e.g., in heat exchangers based on steam condensation.

  5. Electron Impact Excitation of Noble Gases

    NASA Astrophysics Data System (ADS)

    Zeman, Vlado; Bartschat, Klaus

    1998-05-01

    We have extended our Breit-Pauli R-matrix work [1,2] to model electron impact excitation of the [np^5(n+1)s] and [np^5(n+1)p] states in the noble gases Ne--Xe. Total and differential cross sections, the polarization of emitted light, and spin asymmetry parameters will be presented for incident electron energies between threshold and 30 eV. The results will be analyzed and compared with a large amount of recent experimental data [3--8]. 1. V. Zeman et al., Phys. Rev. Lett. 79, 1825 (1997) 2. V. Zeman and K. Bartschat, J. Phys. B 30, 4609 (1997) 3. C. Norén et al., Phys. Rev. A53, 3253 (1996) and 54, 510 (1996) 4. T.J. Gay et al., Phys. Rev. A53, 1623 (1996) 5. D.H. Yu et al., Phys. Rev. Lett. 78, 2724 (1997); J. Phys. B 30, L461 5. (1997); J. Phys. B 30, 1799 (1997) 6. J.E. Chilton et al., Phys. Rev. A57, 267 (1998) 7. M.A. Khakoo, private communication (1998) 8. M. Dümmler, G.F. Hanne and J. Kessler, J. Phys. B 28, 2985 (1995)

  6. Hybrid synchronization in coupled ultracold atomic gases

    NASA Astrophysics Data System (ADS)

    Qiu, Haibo; Zambrini, Roberta; Polls, Artur; Martorell, Joan; Juliá-Díaz, Bruno

    2015-10-01

    We study the time evolution of two coupled many-body quantum systems, one of which is assumed to be Bose condensed. Specifically, we consider two ultracold atomic clouds each populating two localized single-particle states, i.e., a two-component bosonic Josephson junction. The cold atom cloud can retain its coherence when coupled to the condensate and displays synchronization with the latter, differing from usual entrainment. We term this effect among the ultracold and the condensed clouds as hybrid synchronization. The onset of synchronization, which we observe in the evolution of average properties of both gases when increasing their coupling, is found to be related to the many-body properties of the quantum gas, e.g., condensed fraction quantum fluctuations of the particle number differences. We discuss the effects of different initial preparations and the influence of unequal particle numbers for the two clouds, and we explore the dependence on the initial quantum state, e.g., coherent state, squeezed state, and Fock state, finding essentially the same phenomenology in all cases.

  7. Quantum Degenerate Gases of Atomic Strontium

    NASA Astrophysics Data System (ADS)

    Killian, T. C.

    2010-03-01

    This talk will describe the production and properties of a Bose-Einstein condensate of ^84Sr and a quantum degenerate mixture of ^87Sr (fermion) and ^88Sr (boson). ^88Sr has a small negative scattering length leading to a maximum condensate size for our trapping conditions of about 10^4 atoms. ^87Sr is used to sympathetically cool ^88Sr, but it is also of interest for study of quantum degenerate Fermi gases because it has a large nuclear spin (I=9/2). Alkaline-earth metal atoms and atoms with similar electronic structure are of interest for quantum computing proposals, cold collision studies, and investigation of quantum fluids. There are a wealth of isotopes that allow mass-tuning of interactions and creation of various quantum mixtures. The two-valence electrons lead to a singlet ground state and narrow intercombination transitions to metastable triplet states, offering the promise of low-loss optical Feshbach resonances for manipulating scattering lengths. Fermions often have large nuclear spin, which is decoupled from electronic degrees of freedom and leads to a large degree of symmetry and degeneracy in the interaction Hamiltonian. Work done in collaboration with Y.N. Martinez de Escobar, P.G. Mickelson, M. Yan, B.J. DeSalvo, and S.B. Nagel, Rice University.

  8. Implementation of non-condensable gases condensation suppression model into the WCOBRA/TRAC-TF2 LOCA safety evaluation code

    SciTech Connect

    Liao, J.; Cao, L.; Ohkawa, K.; Frepoli, C.

    2012-07-01

    The non-condensable gases condensation suppression model is important for a realistic LOCA safety analysis code. A condensation suppression model for direct contact condensation was previously developed by Westinghouse using first principles. The model is believed to be an accurate description of the direct contact condensation process in the presence of non-condensable gases. The Westinghouse condensation suppression model is further revised by applying a more physical model. The revised condensation suppression model is thus implemented into the WCOBRA/TRAC-TF2 LOCA safety evaluation code for both 3-D module (COBRA-TF) and 1-D module (TRAC-PF1). Parametric study using the revised Westinghouse condensation suppression model is conducted. Additionally, the performance of non-condensable gases condensation suppression model is examined in the ACHILLES (ISP-25) separate effects test and LOFT L2-5 (ISP-13) integral effects test. (authors)

  9. EDITORIAL: The 20th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases The 20th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases

    NASA Astrophysics Data System (ADS)

    Petrovi?, Zoran Lj; Mari?, Dragana; Malovi?, Gordana

    2011-03-01

    This special issue consists of papers that are associated with invited lectures, workshop papers and hot topic papers presented at the 20th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases (ESCAMPIG XX). This conference was organized in Novi Sad (Serbia) from 13 to 17 July 2010 by the Institute of Physics of the University of Belgrade. It is important to note that this is not a conference 'proceedings'. Following the initial selection process by the International Scientific Committee, all papers were submitted to the journal by the authors and have been fully peer reviewed to the standard required for publication in Plasma Sources Science and Technology (PSST). The papers are based on presentations given at the conference but are intended to be specialized technical papers covering all or part of the topic presented by the author during the meeting. The ESCAMPIG conference is a regular biennial Europhysics Conference of the European Physical Society focusing on collisional and radiative aspects of atomic and molecular physics in partially ionized gases as well as on plasma-surface interaction. The conference focuses on low-temperature plasma sciences in general and includes the following topics: Atomic and molecular processes in plasmas Transport phenomena, particle velocity distribution function Physical basis of plasma chemistry Plasma surface interaction (boundary layers, sheath, surface processes) Plasma diagnostics Plasma and discharges theory and simulation Self-organization in plasmas, dusty plasmas Upper atmospheric plasmas and space plasmas Low-pressure plasma sources High-pressure plasma sources Plasmas and gas flows Laser-produced plasmas During ESCAMPIG XX special sessions were dedicated to workshops on: Atomic and molecular collision data for plasma modeling, organized by Professors Z Lj Petrovic and N Mason Plasmas in medicine, organized by Dr N Puac and Professor G Fridman. The conference topics were represented in the program by 16 invited lectures, 7 selected hot topics, and 191 poster presentations. The largest number of contributed papers was submitted in Topic 5: Plasma diagnostics (37). The workshop topics were addressed by 10 invited lectures, 5 oral presentations and 7 posters. A post-conference workshop with 5 invited lectures was organized, dealing with the data needs for modeling of plasma sources of light. ESCAMPIG XX was attended by 185 scientists from 31 countries. Of the participants, 30% were PhD students (55). The list includes scientists from the USA, Japan, Australia, Mexico and other non-European countries, which indicates the truly international status of the conference. We would like to thank the authors for their efforts in preparing stimulating lectures and interesting articles for the readers of PSST, and the scientific community dealing with ionized gases, plasma sources and atomic, molecular and chemical physics of low-temperature plasmas for continued interest in the field of ESCAMPIG. We would like to thank the organizers of all previous ESCAMPIG conferences for setting the standards for organization and, in particular, the organizers of ESCAMPIG XVIII and XIX for their direct help and insight. Finally the International Scientific Committee and its chairman in particular have worked hard to select the best possible program and to keep us in line with almost 40 years of tradition and standards of the conference. Most importantly this has been the 20th conference. The quality of new papers shows maturity and new vistas in the field that has produced so much fundamental understanding of complex, non-equilibrium, even nonlinear plasmas. At the same time the field has led to some of the key technologies of modern civilization and has shown that responsible science that pays attention to its societal benefits should have no fear for its future. All critical issues studied today were presented at the meeting and only a small part is represented here. For example, discharges in liquids or above liquids were covered by several lectures represented by two pa

  10. From cavity QED with quantum gases to optomechanics

    SciTech Connect

    Ritsch, Helmut

    2011-10-03

    We study the nonlinear coupled dynamics of ultra-cold quantum gases trapped in the light field of high Q optical resonators. In the very low temperature limit the quantum nature of both, light and ultra-cold matter play equally important roles. Using the dynamically generated entanglement and properly designed measurements procedures of the light field allows controlled preparation of many-body atomic states as e.g. atom number squeezed states or Schroedinger cat states. If one traps the particles inside the optical cavity, one can create a optical potential, which is a quantized and a dynamical variable itself. In addition it mediates controllable long range interactions. The self-consistent solution for light and particles the includes new classes of quantum many-body states as super-solid states and polaron like excitations. In the deep trap limit the collective coupling of the particles and the field can be tailored to reproduce a wide range of optomechanic Hamiltonians with linear, quadratic or even higher order couplings in an environment very close to zero temperature.

  11. Physics of Electric Discharges in Atmospheric Gases: An Informal Introduction

    NASA Astrophysics Data System (ADS)

    Treumann, Rudolf A.; K?os, Zbigniew; Parrot, Michel

    2008-06-01

    A short account of the physics of electrical discharges in gases is given from the viewpoint of its historical evolution and application to planetary atmospheres. As such it serves as an introduction to the papers on particular aspects of electric discharges contained in this issue, in particular in the chapters on lightning and the discharges which in the last two decades have been observed to take place in Earth’s upper atmosphere. In addition to briefly reviewing the early history of gas discharge physics we discuss the main parameters affecting atmospheric discharges like collision frequency, mean free path and critical electric field strength. Any discharge current in the atmosphere is clearly carried only by electrons. Above the lower boundary of the mesosphere the electrons must be considered magnetized with the conductivity becoming a tensor. Moreover, the collisional mean free path in the upper atmosphere becomes relatively large which lowers the critical electric field there and more easily enables discharges than at lower altitudes. Finally we briefly mention the importance of such discharges as sources for wave emission.

  12. Physics of Electric Discharges in Atmospheric Gases: An Informal Introduction

    NASA Astrophysics Data System (ADS)

    Treumann, Rudolf A.; K?os, Zbigniew; Parrot, Michel

    A short account of the physics of electrical discharges in gases is given from the viewpoint of its historical evolution and application to planetary atmospheres. As such it serves as an introduction to the papers on particular aspects of electric discharges contained in this issue, in particular in the chapters on lightning and the discharges which in the last two decades have been observed to take place in Earth's upper atmosphere. In addition to briefly reviewing the early history of gas discharge physics we discuss the main parameters affecting atmospheric discharges like collision frequency, mean free path and critical electric field strength. Any discharge current in the atmosphere is clearly carried only by electrons. Above the lower boundary of the mesosphere the electrons must be considered magnetized with the conductivity becoming a tensor. Moreover, the collisional mean free path in the upper atmosphere becomes relatively large which lowers the critical electric field there and more easily enables discharges than at lower altitudes. Finally we briefly mention the importance of such discharges as sources for wave emission.

  13. Habitat: importance, destruction, & Habitat: importance, destruction, &

    E-print Network

    Limburg, Karin E.

    Habitat: importance, destruction, & evaluation #12;Habitat: importance, destruction, & evaluation Organisms Habitat People Taxonomy Ecology Population dynamics Life history Stocking Introductions Population Biodiversity Genetics Restoration #12;What is habitat for fish? · Habitat for fish includes all of the physical

  14. Highly sensitive phototransistor based on GaSe nanosheets

    NASA Astrophysics Data System (ADS)

    Huang, Hai; Wang, Peng; Gao, Yanqing; Wang, Xudong; Lin, Tie; Wang, Jianlu; Liao, Lei; Sun, Jinglan; Meng, Xiangjian; Huang, Zhiming; Chen, Xiaoshuang; Chu, Junhao

    2015-10-01

    Phototransistors based on two dimensional semiconductors have drawn increasing attention in recent years. GaSe is a typical semiconductor with a layered structure. In this work, the ultrathin GaSe nanosheets were exfoliated from commercially available crystals using a micromechanical cleavage technique. Then, the nanosheets were used to fabricate field effect transistors (FETs) on Si/SiO2 substrates with interdigitated electrodes. The electrical and optoelectronic properties of the FET were characterized. The phototransistor based on a GaSe nanosheet had a high photoresponsivity (˜2200 mA/W) and a high Iphoto/Idark (photoresponse current over dark current) ratio of almost 103.

  15. Cryogenic method for measuring nuclides and fission gases

    DOEpatents

    Perdue, P.T.; Haywood, F.F.

    1980-05-02

    A cryogenic method is provided for determining airborne gases and particulates from which gamma rays are emitted. A special dewar counting vessel is filled with the contents of the sampling flask which is immersed in liquid nitrogen. A vertically placed sodium-iodide or germanium-lithium gamma-ray detector is used. The device and method are of particular use in measuring and identifying the radioactive noble gases including emissions from coal-fired power plants, as well as fission gases released or escaping from nuclear power plants.

  16. Nitrogen and light noble gases in Parsa enstatite chondrite

    NASA Technical Reports Server (NTRS)

    Murty, S. V. S.

    1993-01-01

    Solar gases have been recently reported in Parsa, an EH3 chondrite. In an effort to check whether solar gases are uniformly distributed throughout Parsa or they are located in specific phases, we analyzed two additional samples of bulk Parsa and one aubritic nodule for N and noble gases. Nitrogen studies are intended for the understanding of the nitrogen components distribution in E-chondrites. The N-systematics of the nodule are entirely different from the bulk samples. The higher N contents in this nodule, as well as its complex delta(sup 15)N structure, as compared to the normal aubrites, is suggestive that the nodule is not a genuine aubrite.

  17. Defects in GaSe grown by Bridgman method.

    PubMed

    Kokh, K A; Atuchin, V V; Gavrilova, T A; Kozhukhov, A; Maximovskiy, E A; Pokrovsky, L D; Tsygankova, A R; Saprykin, A I

    2014-12-01

    Optical quality GaSe crystals have been grown by vertical Bridgman method. The structural properties and micromorphology of a cleaved GaSe(001) surface have been evaluated by RHEED, SEM and AFM. The cleaved GaSe(001) is atomically flat with as low roughness as ?0.06 nm excepting local hillock type defects. The hillock-type formations are round-shaped with a bottom diameter of ?200 nm and a height of ?20-35 nm. The drastic depletion of the hillock material by gallium has been indicated by EDX measurements. PMID:25182595

  18. Quasi-real-time monitoring of SW radiation budget using geostationary satellite for Climate study and Renewable energy. (Invited)

    NASA Astrophysics Data System (ADS)

    Takenaka, H.; Nakajima, T. Y.; Kuze, H.; Takamura, T.; Pinker, R. T.; Nakajima, T.

    2013-12-01

    Solar radiation is the only source of energy that drives the weather and climate of the Earth's surface. Earth is warmed by incoming solar radiation, and emitted energy to space by terrestrial radiation due to its temperature. It has been kept to the organisms viable environment by the effect of heating and cooling. Clouds can cool the Earth by reflecting solar radiation and also can keep the Earth warm by absorbing and emitting terrestrial radiation. They are important in the energy balance at the Earth surface and the Top of the Atmosphere (TOA) and are connected complicatedly into the Earth system as well as other climate feedback processes. Thus it is important to estimate Earth's radiation budget for better understanding of climate and environmental change. We have shared several topics related to climate change. Energy issues close to the climate change, it is an environmental problems. Photovoltaics is one of the power generation method to converts from solar radiation to electric power directly. It does not emit greenhouse gases during power generation. Similarly, drainage, exhaust, vibration does not emit. PV system can be distributed as a small power supply in urban areas and it can installed to near the power demand points. Also solar thermal is heat generator with high efficiency. Therefor it is an effective energy source that the solar power is expected as one of the mitigation of climate change (IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation). It is necessary to real-time-monitoring of the surface solar radiation for safety operation of electric power system. We introduce a fusion analysis of renewable energy and Quasi-real-time analysis of SW radiation budget. Sample of estimated PV power mapping using geostationary satellite.

  19. Radiation protection and instrumentation

    NASA Technical Reports Server (NTRS)

    Bailey, J. V.

    1975-01-01

    Radiation was found not to be an operational problem during the Apollo program. Doses received by the crewmen of Apollo missions 7 through 17 were small because no major solar-particle events occurred during those missions. One small event was detected by a radiation sensor outside the Apollo 12 spacecraft, but no increase in radiation dose to the crewmen inside the spacecraft was detected. Radiation protection for the Apollo program was focused on both the peculiarities of the natural space radiation environment and the increased prevalence of manmade radiation sources on the ground and onboard the spacecraft. Radiation-exposure risks to crewmen were assessed and balanced against mission gain to determine mission constraints. Operational radiation evaluation required specially designed radiation detection systems onboard the spacecraft in addition to the use of satellite data, solar observatory support, and other liaison. Control and management of radioactive sources and radiation-generating equipment was important in minimizing radiation exposure of ground-support personnel, researchers, and the Apollo flight and backup crewmen.

  20. Observations of atmospheric trace gases by MAX-DOAS in the coastal boundary layer over Jiaozhou Bay

    NASA Astrophysics Data System (ADS)

    Li, Xianxin; Wang, Zhangjun; Meng, Xiangqian; Zhou, Haijin; Du, Libin; Qu, Junle; Chen, Chao; An, Quan; Wu, Chengxuan; Wang, Xiufen

    2014-11-01

    Atmospheric trace gases exist in the atmosphere of the earth rarely. But the atmospheric trace gases play an important role in the global atmospheric environment and ecological balance by participating in the global atmospheric cycle. And many environmental problems are caused by the atmospheric trace gases such as photochemical smog, acid rain, greenhouse effect, ozone depletion, etc. So observations of atmospheric trace gases become very important. Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) developed recently is a kind of promising passive remote sensing technology which can utilize scattered sunlight received from multiple viewing directions to derive vertical column density of lower tropospheric trace gases like ozone, sulfur dioxide and nitrogen dioxide. It has advantages of simple structure, stable running, passive remote sensing and real-time online monitoring automatically. A MAX-DOAS has been developed at Shandong Academy of Sciences Institute of Oceanographic Instrumentation (SDIOI) for remote measurements of lower tropospheric trace gases (NO2, SO2, and O3). In this paper, we mainly introduce the stucture of the instrument, calibration and results. Detailed performance analysis and calibration of the instrument were made at Qingdao. We present the results of NO2, SO2 and O3 vertical column density measured in the coastal boundary layer over Jiaozhou Bay. The diurnal variation and the daily average value comparison of vertical column density during a long-trem observation are presented. The vertical column density of NO2 and SO2 measured during Qingdao oil pipeline explosion on November 22, 2013 by MAX-DOAS is also presented. The vertical column density of NO2 reached to a high value after the explosion. Finally, the following job and the outlook for future possible improvements are given. Experimental calibration and results show that the developed MAX-DOAS system is reliable and credible.

  1. Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases Fiscal Year 2000 Annual Report

    SciTech Connect

    Cushman, R.M.

    2001-11-15

    The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has, since its inception in 1982, enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change, including concentrations of carbon dioxide (CO{sub 2}) and other radiatively active gases in the atmosphere; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; emissions of CO{sub 2} and other trace gases to the atmosphere; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea levels.

  2. Numerical prediction of radiative heat transfer in reciprocating superadiabatic combustion in porous media.

    PubMed

    Du, Liming; Xie, Maozhao

    2011-06-01

    A numerical study of Reciprocating Superadiabatic Combustion of Premixed gases in porous media (hereafter, referred to as RSCP) is performed. In this system the transient combustion of methane-air mixture is stabilized in a porous media combustor by periodically switching flow directions. The mass, momentum, energy and species conservation equations are solved using a two-dimensional control volume method. Local thermal non-equilibrium between the gas and the solid phases is considered by solving separate energy equations for the two phases and coupling them through a convective heat transfer coefficient. The porous media is assumed to emit, absorb and isotropically scatter radiation. The influences of the dominating operating parameters, such as filtration velocity, equivalence ratio and half cycle on the temperature profile, heat release rate, radiant flux, radiant efficiency and combustion efficiency are discussed. The results show that coupling calculating of flow field, combustion reaction and volume radiation of the optically thick media is successively achieved and heat radiation plays an important role in the overall performance of the burner. The temperature profile inside the RSCP combustor has a typical trapezoidal shape and the profile of radiation flux is similar to sinusoidal shape. Compared with the conventional premixed combustion in porous medium, combustion behavior in RSCP combustor is superior, such as better thermal structure and higher radiation efficiency and combustion efficiency. PMID:25084588

  3. Remote Sensing Observations of Greenhouse Gases from space based and airborne platforms: from SCIAMACHY and MaMap to CarbonSat

    NASA Astrophysics Data System (ADS)

    Burrows, John P.; Schneising, Oliver; Buchwitz, Michael; Bovensmann, Heinrich; Heymann, Jens; Gerilowski, Konstantin; Krings, Thomas; Krautwurst, Sven; Dickerson, Russ

    2015-04-01

    Methane, CH4, e and carbon dioxide, CO2, play an important role in the earth carbon cycle. They are the two most important long lived greenhouse gases produced by anthropogenic fossil fuel combustion. In order to assess accurately the surface fluxes of CH4 or CO2. The Scanning Imaging Absorption Spectrometer for Atmospheric ChartographY, SCIAMACHY, was a national contribution to the ESA Envisat platform: the latter being launched on the 28th February 2002 and operating successfully until April 2012. The SCIAMACHY measurements of the up-welling radiation have been used to retrieve the dry mole fraction of XCH4 and XCO2, providing a unique 10 year record at the spatial resolution of 60 kmx30 km. This data has been used to observe the changing CH4 abundance in the atmosphere and identify anthropogenic such as Fracking and natural sources such as wetlands. The Methane and carbon dioxide Mapper, MaMap, was developed as an aircraft demonstration instrument for our CarbonSat and CarbonSat Constellation concepts. CarbonSat is in Phase A B1 studies as one of two candidate missions for ESA's Earth Explorer 8 Mission. Selected results from SCIAMACHY and Mamap will be presented with a focus on methane and the perspective for CarbonSat.

  4. Thermo-optical piston in gases

    SciTech Connect

    Chermyaninov, I. V.; Chernyak, V. G.

    2014-12-09

    The new steady state of the gas – thermo-optical pressure difference is considered. This condition occurs in the gas that is in a closed capillary in the field of resonant laser radiation and a temperature gradient. The pressure difference at the ends of the capillary is determined by the interaction of three fluxes – thermal creep, the light-induced drift and Poiseuille flux. Laser radiation and the temperature gradient play the role of thermo-optical piston (TOP) which compresses the gas in different ends of the capillary. The problem is solved based on the linearized Boltzmann kinetic equations that take into account the induced and spontaneous transitions in atoms or molecules. Expressions for the kinetic coefficients defining TOP-effect are obtained in the case of a nearly free-molecular regime. Numerical estimates of the TOP-effect are given for sodium vapor.

  5. Analysis of air pollution and greenhouse gases

    SciTech Connect

    Benkovitz, C.M.

    1992-03-01

    The current objective of the project Analysis of Air Pollution and Greenhouse Gases'' is to develop a study of emissions and emission sources that could easily be linked to models of economic activity. Initial studies were conducted to evaluate data currently available linking activity rates and emissions estimates. The emissions inventory developed for the National Acid Precipitation Assessment Program (NAPAP) presents one of the most comprehensive data sets, and was chosen for our initial studies, which are described in this report. Over 99% of the SO{sub 2} emissions, 98% of the NO{sub x} emission and 57% of the VOC emissions from area sources are related to fuel combustion. The majority of emission from these sources are generated by the transportation sector. Activity rates for area sources are not archived with the NAPAP inventory; alternative derivations of these data will be part of the future activities of this project. The availability and completeness of the fuel heat content data in the NAPAP inventory were also studied. Approximately 10% of the SO{sub 2} emissions, 13% of the NO{sub x} emissions and 46% of the VOC emissions are generated by sources with unavailable data for fuel heat content. Initial estimates of pollutant emission rate per unit fuel heat content. Initial estimates of pollutant emission rate per unit fuel heat content were generated. Future studies for this project include the derivation of activity rates for area sources, improved explanations for the default fuel parameters defined in the NAPAP inventory and the development of links to data bases of economic activity.

  6. EDITORIAL: The Earth radiation balance as driver of the global hydrological cycle

    NASA Astrophysics Data System (ADS)

    Wild, Martin; Liepert, Beate

    2010-06-01

    Variations in the intensity of the global hydrological cycle can have far-reaching effects on living conditions on our planet. While climate change discussions often revolve around possible consequences of future temperature changes, the adaptation to changes in the hydrological cycle may pose a bigger challenge to societies and ecosystems. Floods and droughts are already today amongst the most damaging natural hazards, with floods being globally the most significant disaster type in terms of loss of human life (Jonkman 2005). From an economic perspective, changes in the hydrological cycle can impose great pressures and damages on a variety of industrial sectors, such as water management, urban planning, agricultural production and tourism. Despite their obvious environmental and societal importance, our understanding of the causes and magnitude of the variations of the hydrological cycle is still unsatisfactory (e.g., Ramanathan et al 2001, Ohmura and Wild 2002, Allen and Ingram 2002, Allan 2007, Wild et al 2008, Liepert and Previdi 2009). The link between radiation balance and hydrological cycle Globally, precipitation can be approximated by surface evaporation, since the variability of the atmospheric moisture storage is negligible. This is the case because the fluxes are an order of magnitude larger than the atmospheric storage (423 x 1012 m3 year-1 versus 13 x 1012 m3 according to Baumgartner and Reichel (1975)), the latter being determined by temperature (Clausius-Clapeyron). Hence the residence time of evaporated water in the atmosphere is not more than a few days, before it condenses and falls back to Earth in the form of precipitation. Any change in the globally averaged surface evaporation therefore implies an equivalent change in precipitation, and thus in the intensity of the global hydrological cycle. The process of evaporation requires energy, which it obtains from the surface radiation balance (also known as surface net radiation), composed of the absorbed solar and net thermal radiative exchanges at the Earth's surface. Globally averaged, this surface radiation balance is positive, since radiative absorption, scattering and emission in the climate system act to generate an energy surplus at the surface and an energy deficit in the atmosphere (Liepert 2010). Evaporation, or more precisely its energy equivalent, the latent heat flux, is the main process that compensates for this imbalance between surface and atmosphere, since the latent heat dominates the convective energy flux over sensible heating. The radiative energy surplus at the surface is thus mainly consumed by evaporation and moist convection and subsequently released in the atmosphere through condensation. This implies that any alterations in the available radiative energy will induce changes in the water fluxes. Our focus in this editorial is therefore on the surface radiation balance as the principal driver of the global hydrological cycle. Note that this energetic view is in agreement with that of Richter and Xie (2008) who argue that the spatial and temporal behaviour of the process of evaporation is controlled by surface and atmospheric properties such as atmospheric stability, wind speed, moisture deficit and moisture availability. From radiation theory it is expected that with increasing radiative absorption due to abundance of anthropogenic greenhouse gases in the atmosphere and consequent warming, the emission of thermal energy from the atmosphere towards the surface is increasing (known as downward thermal radiation). This enhances the radiative energy surplus at the surface, and, where surface water is not limited, fuels evaporation besides warming the Earth's surface. The enhanced greenhouse effect therefore tends to accelerate the hydrological cycle, as also shown in many climate model simulations with increasing levels of greenhouse gases (e.g., IPCC 2007, but also see Yang et al 2003, Andrews et al 2009). We can assume that the increase in greenhouse gases since preindustrial times had already led to a substantial increase of downw

  7. Relative Contribution of Greenhouse Gases and Ozone Change to Temperature Trends in the Stratosphere: A Chemistry/Climate Model Study

    NASA Technical Reports Server (NTRS)

    Stolarski, Richard S.; Douglass, A. R.; Newman, P. A.; Pawson, S.; Schoeberl, M. R.

    2006-01-01

    Long-term changes in greenhouse gases, primarily carbon dioxide, are expected to lead to a warming of the troposphere and a cooling of the stratosphere. We examine the cooling of the stratosphere and compare the contributions greenhouse gases and ozone change for the decades between 1980 and 2000. We use 150 years of simulation done with our coupled chemistry/climate model (GEOS 4 GCM with GSFC CTM chemistry) to calculate temperatures and constituents fiom,1950 through 2100. The contributions of greenhouse gases and ozone to temperature change are separated by a time-series analysis using a linear trend term throughout the period to represent the effects of greenhouse gases and an equivalent effective stratospheric chlorine (EESC) term to represent the effects of ozone change. The temperature changes over the 150 years of the simulation are dominated by the changes in greenhouse gases. Over the relatively short period (approx. 20 years) of ozone decline between 1980 and 2000 changes in ozone are competitive with changes in greenhouse gases. The changes in temperature induced by the ozone change are comparable to, but smaller than, those of greenhouse gases in the upper stratosphere (1-3 hPa) at mid latitudes. The ozone term dominates the temperature change near both poles with a negative temperature change below about 3-5 hPa and a positive change above. At mid latitudes in the upper stratosphere and mesosphere (above about 1 hPa) and in the middle stratosphere (3 to 70 ma), the greenhouse has term dominates. From about 70 hPa down to the tropopause at mid latitudes, cooling due to ozone changes is the largest influence on temperature. Over the 150 years of the simulation, the change in greenhouse gases is the most important contributor to temperature change. Ozone caused a perturbation that is expected to reverse over the coming decades. We show a model simulation of the expected temperature change over the next two decades (2006-2026). The simulation shows a crossover between lower atmospheric heating and upper atmospheric cooling that is located at about 90 hPa in the tropics and 30-40 hPa in the polar regions. This results from the combination of continuing increases in greehouse gases and recovery from ozone depletion.

  8. Contributions to the theory of diffusion in gases and liquids 

    E-print Network

    Yang, Li-Ming

    The theory of diffusion in gases has been approached in two different ways in the past. The first is by means of the old free path theory initiated by Maxwell [and] Boltzmann, improved by Tait, Meyer, Jeans and others which ...

  9. An astrophysical view of Earth-based metabolic biosignature gases.

    PubMed

    Seager, Sara; Schrenk, Matthew; Bains, William

    2012-01-01

    Microbial life on Earth uses a wide range of chemical and energetic resources from diverse habitats. An outcome of this microbial diversity is an extensive and varied list of metabolic byproducts. We review key points of Earth-based microbial metabolism that are useful to the astrophysical search for biosignature gases on exoplanets, including a list of primary and secondary metabolism gas byproducts. Beyond the canonical, unique-to-life biosignature gases on Earth (O(2), O(3), and N(2)O), the list of metabolic byproducts includes gases that might be associated with biosignature gases in appropriate exoplanetary environments. This review aims to serve as a starting point for future astrophysical biosignature gas research. PMID:22269061

  10. Studying coherence in ultra-cold atomic gases

    E-print Network

    Miller, Daniel E. (Daniel Edward)

    2007-01-01

    This thesis will discuss the study of coherence properties of ultra-cold atomic gases. The atomic systems investigated include a thermal cloud of atoms, a Bose-Einstein condensate and a fermion pair condensate. In each ...

  11. BIOSIGNATURE GASES IN H?-DOMINATED ATMOSPHERES ON ROCKY EXOPLANETS

    E-print Network

    Seager, Sara

    Super-Earth exoplanets are being discovered with increasing frequency and some will be able to retain stable H2-dominated atmospheres. We study biosignature gases on exoplanets with thin H2 atmospheres and habitable surface ...

  12. Ultralow Electron Temperatures in 2D Electron Gases

    E-print Network

    Zumbühl, Dominik

    Ultralow Electron Temperatures in 2D Electron Gases by efficient silver sinter heat exchangers 3.1 Cold Electrons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2 Kapitza . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.4 Thermal Conduction in Metals . . . . . . . . . . . . . . . . . . . . . 9 3.5 Electron

  13. 40 CFR 258.23 - Explosive gases control.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... by volume of a mixture of explosive gases in air that will propagate a flame at 25 °C and atmospheric pressure. (e) The Director of an approved State may establish alternative frequencies for the...

  14. Multiple carriers of Q noble gases in primitive meteorites

    E-print Network

    Marrocchi, Yves; Estrade, Nicolas

    2015-01-01

    The main carrier of primordial heavy noble gases in chondrites is thought to be an organic phase, known as phase Q, whose precise characterization has resisted decades of investigation. Indirect techniques have revealed that phase Q might be composed of two subphases, one of them associated with sulfide. Here we provide experimental evidence that noble gases trapped within meteoritic sulfides present chemically- and thermally-driven behavior patterns that are similar to Q-gases. We therefore suggest that phase Q is likely composed of two subcomponents: carbonaceous phases and sulfides. In situ decay of iodine at concentrations levels consistent with those reported for meteoritic sulfides can reproduce the 129Xe excess observed for Q-gases relative to fractionated Solar Wind. We suggest that the Q-bearing sulfides formed at high temperature and could have recorded the conditions that prevailed in the chondrule-forming region(s).

  15. Trace Gases, CO2, Climate, and the Greenhouse Effect.

    ERIC Educational Resources Information Center

    Aubrecht, Gordon J., II

    1988-01-01

    Reports carbon dioxide and other trace gases can be the cause of the Greenhouse Effect. Discusses some effects of the temperature change and suggests some solutions. Included are several diagrams, graphs, and a table. (YP)

  16. Method of producing pyrolysis gases from carbon-containing materials

    DOEpatents

    Mudge, Lyle K. (Richland, WA); Brown, Michael D. (West Richland, WA); Wilcox, Wayne A. (Kennewick, WA); Baker, Eddie G. (Richland, WA)

    1989-01-01

    A gasification process of improved efficiency is disclosed. A dual bed reactor system is used in which carbon-containing feedstock materials are first treated in a gasification reactor to form pyrolysis gases. The pyrolysis gases are then directed into a catalytic reactor for the destruction of residual tars/oils in the gases. Temperatures are maintained within the catalytic reactor at a level sufficient to crack the tars/oils in the gases, while avoiding thermal breakdown of the catalysts. In order to minimize problems associated with the deposition of carbon-containing materials on the catalysts during cracking, a gaseous oxidizing agent preferably consisting of air, oxygen, steam, and/or mixtures thereof is introduced into the catalytic reactor at a high flow rate in a direction perpendicular to the longitudinal axis of the reactor. This oxidizes any carbon deposits on the catalysts, which would normally cause catalyst deactivation.

  17. Low-Value Waste Gases as an Energy Source 

    E-print Network

    Waibel, R. T.

    1996-01-01

    Waste gases with potentially useful fuel value are generated at any number of points in refineries, chemical plants and other industrial and commercial sites. The higher quality streams have been utilized successfully in fuel systems for years...

  18. Method for monitoring stack gases for uranium activity

    DOEpatents

    Beverly, Claude R. (Paducah, KY); Ernstberger, Harold G. (Paducah, KY)

    1988-01-01

    A method for monitoring the stack gases of a purge cascade of a gaseous diffusion plant for uranium activity. A sample stream is taken from the stack gases and contacted with a volume of moisture-laden air for converting trace levels of uranium hexafluoride, if any, in the stack gases into particulate uranyl fluoride. A continuous strip of filter paper from a supply roll is passed through this sampling stream to intercept and gather any uranyl fluoride in the sampling stream. This filter paper is then passed by an alpha scintillation counting device where any radioactivity on the filter paper is sensed so as to provide a continuous monitoring of the gas stream for activity indicative of the uranium content in the stack gases.

  19. Method for monitoring stack gases for uranium activity

    DOEpatents

    Beverly, C.R.; Ernstberger, E.G.

    1985-07-03

    A method for monitoring the stack gases of a purge cascade of gaseous diffusion plant for uranium activity. A sample stream is taken from the stack gases and contacted with a volume of moisture-laden air for converting trace levels of uranium hexafluoride, if any, in the stack gases into particulate uranyl fluoride. A continuous strip of filter paper from a supply roll is passed through this sampling stream to intercept and gather any uranyl fluoride in the sampling stream. This filter paper is then passed by an alpha scintillation counting device where any radioactivity on the filter paper is sensed so as to provide a continuous monitoring of the gas stream for activity indicative of the uranium content in the stack gases. 1 fig.

  20. World Energy Projection System Plus Model Documentation: Greenhouse Gases Model

    EIA Publications

    2011-01-01

    This report documents the objectives, analytical approach and development of the World Energy Projection System Plus (WEPS ) Greenhouse Gases Model. It also catalogues and describes critical assumptions, computational methodology, parameter estimation techniques, and model source code.

  1. Radio-frequency spectroscopy of ultracold atomic Fermi gases

    E-print Network

    Schirotzek, Andre

    2010-01-01

    This thesis presents experiments investigating the phase diagram of ultracold atomic Fermi gases using radio-frequency spectroscopy. The tunability of many experimental parameters including the temperature, the interparticle ...

  2. AIR INFILTRATION MEASUREMENTS USING TRACER GASES: A LITERATURE REVIEW

    EPA Science Inventory

    The report gives results of a literature review of air filtration measurements using tracer gases, including sulfur hexafluoride, hydrogen, carbon monoxide, carbon dioxide, nitrous oxide, and radioactive argon and krypton. Sulfur hexafluoride is the commonest tracer gas of choice...

  3. Probing strongly interacting atomic gases with energetic atoms

    E-print Network

    Nishida, Yusuke

    We investigate properties of an energetic atom propagating through strongly interacting atomic gases. The operator product expansion is used to systematically compute a quasiparticle energy and its scattering rate both in ...

  4. A comparative summary on streamers of positive corona discharges in water and atmospheric pressure gases

    NASA Astrophysics Data System (ADS)

    Tachibana, Kunihide; Motomura, Hideki

    2015-07-01

    From an intention of summarizing present understandings of positive corona discharges in water and atmospheric pressure gases, we tried to observe streamers in those media by reproducing and complementing previously reported results under a common experimental setup. We used a point-to-plane electrode configuration with different combinations of electrode gap (7 and 19 mm length) and pulsed power sources (0.25 and 2.5 ?s duration). The general features of streamers were similar and the streamer-to-spark transition was also observed in both the media. However, in the details large differences were observed due to inherent nature of the media. The measured propagation speed of streamers in water of 0.035 × 106 ms-1 was much smaller than the speed in gases (air, N2 and Ar) from 0.4 to 1.1 × 106 ms-1 depending on species. In He the discharge looked glow-like and no streamer was observed. The other characteristics of streamers in gases, such as inception voltage, number of branches and thickness did also depend on the species. The thickness and the length of streamers in water were smaller than those in gases. From the volumetric expansion of a streamer in water after the discharge, the molecular density within the streamer medium was estimated to be rarefied from the density of water by about an order of magnitude in the active discharge phase. We derived also the electron density from the analysis of Stark broadened spectral lines of H and O atoms on the order of 1025 m-3 at the earlier time of the streamer propagation. The analyzed background blackbody radiation, rotational temperature of OH band emission and population density of Cu atomic lines yielded a consistent temperature of the streamer medium between 7000 and 10 000 K. Using the present data with a combination of the analysis of static electric field and previously reported results, we discuss the reason for the relatively low streamer inception voltage in water as compared to the large difference in the medium density between water and gases. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  5. Process for the removal of acid forming gases from exhaust gases

    DOEpatents

    Chang, Shih-Ger (El Cerrito, CA); Liu, David K. (San Pablo, CA)

    1992-01-01

    Exhaust gases are treated to remove NO or NO.sub.x and SO.sub.2 by contacting the gases with an aqueous emulsion or suspension of yellow phosphorus preferably in a wet scrubber. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50.degree. C. are attractive. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO.sub.x and SO.sub.2, alkalis that are used for flue gas desulfurization are preferred. With this process, 100% of the by-products created are usable, and close to 100% of the NO or NO and SO.sub.2 can be removed in an economic fashion.

  6. Process for the removal of acid forming gases from exhaust gases

    DOEpatents

    Chang, S.G.; Liu, D.K.

    1992-11-17

    Exhaust gases are treated to remove NO or NO[sub x] and SO[sub 2] by contacting the gases with an aqueous emulsion or suspension of yellow phosphorus preferably in a wet scrubber. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50 C is attractive. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO[sub x] and SO[sub 2], alkalis that are used for flue gas desulfurization are preferred. With this process, 100% of the by-products created are usable, and close to 100% of the NO or NO[sub x] and SO[sub 2] can be removed in an economic fashion. 9 figs.

  7. Robust IR Remote Sensing Technique of the Total Column of Trace Gases Including Carbon Dioxide and Methane

    NASA Technical Reports Server (NTRS)

    Georgieva, E. M.; Heaps, W. S.

    2011-01-01

    Progress on the development of a differential radiometer based upon the Fabry-Perot interferometer (FPI) for methane (CH4) and carbon dioxide (C02) detection in the atmosphere is presented. Methane measurements are becoming increasingly important as a component of NASA's programs to understand the global carbon cycle and quantifY the threat of global warming. Methane is the third most important greenhouse gas in the Earth's radiation budget (after water vapor and carbon dioxide) and the second most important anthropogenic contributor to global warming. The importance of global warming and air quality to society caused the National Research Council to recommend that NASA develop the following missions [1]: ASCENDS (Active Sensing of C02 Emissions over Nights, Days, and Seasons), GEOCAPE (Geostationary Coastal and Air Pollution Events), and GACM (Global Atmosphere Composition Mission). Though methane measurements are not specifically called out in these missions, ongoing environmental changes have raised the importance of understanding the methane budget. In the decadal survey is stated that "to close the carbon budget, we would also address methane, but the required technology is not obvious at this time. If appropriate and cost-effective methane technology becomes available, we strongly recommend adding a methane capability". In its 2007 report the International Panel on Climate Change identified methane as a key uncertainty in our understanding saying that the causes of recent changes in the growth rate of atmospheric CH4 are not well understood. What we do know is that methane arises from a number of natural sources including wet lands and the oceans plus man made sources from agriculture, as well as coal and petroleum production and distribution. It has recently been pointed out that large amount of methane are frozen in the permafrost of Canada and Siberia. There is a fear that melting of this permafrost driven by global warming may release large amounts of methane very suddenly further exacerbating climate change [2]. Last year our group began a joint effort with Johns Hopkins Applied Physics Laboratory to investigate the possibility of developing a small unmanned aerial vehicle (UAV) equipped to measure greenhouse gases-particularly methane. Although we are targeting our system for smaller UAV's the instrument will be directly applicable to missions involving larger NASA UAV's such as Global Hawk or even on missions utilizing manned aircraft. Because of its small size, inherent ruggedness and simplicity some version of our proposed instrument may find a role as a satellite instrument for NASA or NOAA.

  8. Radiation sickness

    MedlinePLUS

    ... radiation, such as radiation from a nuclear power plant accident Exposure to excessive radiation for medical treatments ... stops ongoing contamination. Vigorously wash the victim with soap and water. Dry the victim and wrap with ...

  9. Radiation therapy

    MedlinePLUS

    Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells. ... faster than normal cells in the body. Because radiation is most harmful to quickly growing cells, radiation ...

  10. Radiation Therapy

    MedlinePLUS

    Radiation therapy is a cancer treatment. It uses high doses of radiation to kill cancer cells and stop them from ... half of all cancer patients receive it. The radiation may be external, from special machines, or internal, ...

  11. Radiation Therapy

    MedlinePLUS

    ... Your Best Self Smart Snacking Losing Weight Safely Radiation Therapy KidsHealth > Teens > Diseases & Conditions > Cancer & Tumors > Radiation ... how to cope with side effects. What Is Radiation Therapy? Cancer is a disease that causes cells ...

  12. Switch Box For Controlling Flows Of Four Gases

    NASA Technical Reports Server (NTRS)

    Wishard, James R.; Lamb, James L.

    1995-01-01

    Switch box designed for use in simultaneously controlling flows of as many as four out of total of six available gases into semiconductor-processing chamber. Contains switches, relays, logic circuitry, display devices, and other circuitry for connecting each of as many as four gas controllers to any one of as many as six available mass-flow controllers. Front panel of switch box apprises technician of statuses of flows of various gases.

  13. Chemical recognition of gases and gas mixtures with terahertz waves

    NASA Astrophysics Data System (ADS)

    Jacobsen, R. H.; Mittleman, D. M.; Nuss, M. C.

    1996-12-01

    A time-domain chemical-recognition system for classifying gases and analyzing gas mixtures is presented. We analyze the free induction decay exhibited by gases excited by far-infrared (terahertz) pulses in the time domain, using digital signal-processing techniques. A simple geometric picture is used for the classification of the waveforms measured for unknown gas species. We demonstrate how the recognition system can be used to determine the partial pressures of an ammonia-water gas mixture.

  14. Production of Greenhouse Gases in The Atmosphere of Early Mars

    NASA Technical Reports Server (NTRS)

    Kress, Monika E.; McKay, Christopher P.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Mars was much warmer and wetter 3.5 to 4 billion years ago than it is today, suggesting that its climate was able to support life in the distant past. Carbon dioxide and methane are greenhouse gases which may have kept Mars warm during this time. We explore the possibility that these gases were produced via grain-catalyzed reactions in the warm, dusty aftermath of large comet and/or asteroid impacts which delivered Mars, volatile inventory.

  15. Biological production of ethanol from waste gases with Clostridium ljungdahlii

    DOEpatents

    Gaddy, James L. (Fayetteville, AR)

    2000-01-01

    A method and apparatus for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, and methanol production, into useful products is disclosed. The method includes introducing the waste gases into a bioreactor where they are fermented to various product, such as organic acids, alcohols H.sub.2, SCP, and salts of organic acids by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified.

  16. Combined conduction and radiation heat transfer in concentric cylindrical media

    NASA Technical Reports Server (NTRS)

    Pandey, D. K.

    1987-01-01

    The exact radiative transfer expressions for gray and nongray gases which are absorbing, emitting and nonscattering, contained between infinitely long concentric cylinders with black surfaces, are given in local thermodynamic equilibrium. Resulting energy equations due to the combination of conduction and radiation modes of heat transfer, under steady state conditions for gray and nongray media, are solved numerically using the undetermined parameters method. A single 4.3-micron band of CO2 is considered for the nongray problems. The present solutions for gray and nongray gases obtained in the plane-parallel limit (radius ratio approaches to one) are compared with the plane-parallel results reported in the literature.

  17. Comparative Climate Responses of Anthropogenic Greenhouse Gases, All Major Aerosol Components, Black Carbon, and Methane, Accounting for the Evolution of the Aerosol Mixing State and of Clouds/Precipitation from Multiple Aerosol Size Distributions

    NASA Astrophysics Data System (ADS)

    Jacobson, M. Z.

    2005-12-01

    Several modeling studies to date have simulated the global climate response of anthropogenic greenhouse gases and bulk (non-size-resolved) sulfate or generic aerosol particles together, but no study has examined the climate response of greenhouse gases simultaneously with all major size- and composition resolved aerosol particle components. Such a study is important for improving our understanding of the effects of anthropogenic pollutants on climate. Here, the GATOR-GCMOM model is used to study the global climate response of (a) all major greenhouse gases and size-resolved aerosol components, (b) all major greenhouse gases alone, (c) fossil-fuel soot (black carbon, primary organic matter, sulfuric acid, bisulfate, sulfate), and (d) methane. Aerosol components treated in all simulations included water, black carbon, primary organic carbon, secondary organic carbon, sulfuric acid, bisulfate, sulfate, nitrate, chloride, ammonium, sodium, hydrogen ion, soil dust, and pollen/spores. Fossil-fuel soot (FFS) was emitted into its own size distribution. All other components, including biofuel and biomass soot, sea-spray, soil dust, etc., were emitted into a second distribution (MIX). The FFS distribution grew by condensation of secondary organic matter and sulfuric acid, hydration of water, and dissolution of nitric acid, ammonia, and hydrochloric acid. It self-coagulated and heterocoagulated with the MIX distribution, which also grew by condensation, hydration, and dissolution. Treatment of separate distributions for FFS allowed FFS to evolve from an external mixture to an internal mixture. In both distributions, black carbon was treated as a core component for optical calculations. Both aerosol distributions served as CCN during explicit size-resolved cloud formation. The resulting clouds grew by coagulation and condensation, coagulated with interstitial aerosol particles, and fell to the surface as rain and snow, carrying aerosol constituents with them. Thus, cloud evolution accounted for the first and second indirect effects and the mixing state of aerosol particles. The optical properties of clouds were found by treating black carbon inclusions surrounded by a shell of water. The albedos of snow, sea ice, and water were calculated with radiative transfer solutions, assuming black carbon inclusions in the case of snow and sea ice. The simulations accounted for 3-D energy diffusion to the deep ocean and 2-D ocean circulation. Major conclusions are (a) the most important constituents of global warming, in terms of climate response, appear to be, in order, carbon dioxide, black carbon, and methane, (b) aerosol particles (all together) appear to act on top of greenhouse gases to enhance extremes in both regional cooling and regional warming, (b) the combination of important greenhouse gases and aerosol particles can explain observed major regions of historic warming and cooling, and (d) eliminating all anthropogenic aerosol emission could more than double current global warming but would have less of an effect than independently doubling carbon dioxide.

  18. Effects of Radiative Emission and Absorption on the Propagation and Extinction of Premixed Gas Flames

    NASA Technical Reports Server (NTRS)

    Ju, Yiguang; Masuya, Goro; Ronney, Paul D.

    1998-01-01

    Premixed gas flames in mixtures of CH4, O2, N2, and CO2 were studied numerically using detailed chemical and radiative emission-absorption models to establish the conditions for which radiatively induced extinction limits may exist independent of the system dimensions. It was found that reabsorption of emitted radiation led to substantially higher burning velocities and wider extinction limits than calculations using optically thin radiation models, particularly when CO2, a strong absorber, is present in the unburned gas, Two heat loss mechanisms that lead to flammability limits even with reabsorption were identified. One is that for dry hydrocarbon-air mixtures, because of the differences in the absorption spectra of H2O and CO2, most of the radiation from product H2O that is emitted in the upstream direction cannot be absorbed by the reactants. The second is that the emission spectrum Of CO2 is broader at flame temperatures than ambient temperature: thus, some radiation emitted near the flame front cannot be absorbed by the reactants even when they are seeded with CO2 Via both mechanisms, some net upstream heat loss due to radiation will always occur, leading to extinction of sufficiently weak mixtures. Downstream loss has practically no influence. Comparison with experiment demonstrates the importance of reabsorption in CO2 diluted mixtures. It is concluded that fundamental flammability limits can exist due to radiative heat loss, but these limits are strongly dependent on the emission-absorption spectra of the reactant and product -gases and their temperature dependence and cannot be predicted using gray-gas or optically thin model parameters. Applications to practical flames at high pressure, in large combustion chambers, and with exhaust-gas or flue-gas recirculation are discussed.

  19. Biomass Burning and the Production of Greenhouse Gases. Chapter 9

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.

    1994-01-01

    Biomass burning is a source of greenhouse gases, carbon dioxide, methane, and nitrous oxide. In addition, biomass burning is a source of chemically active gases, including carbon monoxide, nonmethane hydrocarbons, and nitric oxide. These gases, along with methane, lead to the chemical production of tropospheric ozone (another greenhouse gas) as well as control the concentration of the hydroxyl radical, which regulates the lifetime of almost every atmospheric gas. Following biomass burning, biogenic emissions of nitrous oxide, nitric oxide, and methane are significantly enhanced. It is hypothesized that enhanced postburn biogenic emissions of these gases are related to fire-induced changes in soil chemistry and/or microbial ecology. Biomass burning, once believed to be a tropical phenomenon, has been demonstrated by satellite imagery to also be a regular feature of the world's boreal forests. One example of biomass burning is the extensive 1987 fire that destroyed more than 12 million acres of boreal forest in the People's Republic of China and across its border in the Soviet Union. Recent estimates indicate that almost all biomass burning is human-initiated and that it is increasing with time. With the formation of greenhouse and chemically active gases as direct combustion products and a longer-term enhancement of biogenic emissions of gases, biomass burning may be a significant driver for global change.

  20. Constraints on the origins of hydrocarbon gas from compositions of gases at their site of origin

    USGS Publications Warehouse

    Price, L.C.; Schoell, M.

    1995-01-01

    IT is widely accepted that natural gas is formed from thermal decomposition of both oil in reservoirs and, to a lesser extent, the organic matter in shales from which the oil was derived1-6. But laboratory pyrolysis experiments on shales do not reproduce the methane-rich composition typical of most gas reservoirs7, leading to suggestions7 that other mechanisms, such as transition-metal catalysis, may be important. The discrepancy might, however, instead arise because gas (and oil) deposits have migrated from their source rocks, so that the reservoir composition might not be representative of the composition in the source rocks where the hydrocarbons were generated. To address this question, we have analysed gas samples coproduced with oils directly from a source rock (the Bakken shales, North Dakota, USA) where the local geology has prevented significant hydrocarbon migration. The methane contents of these Bakken-shale gases are much lower than that of conventional gas reservoirs, but are consistent with that from pyrolysis experiments8,9 on these shales. Thus, because these Bakken gases form with (rather than from) oils, we argue that compositional differences between gases from source rocks and conventional gas deposits result from fractionation processes occurring after hydrocarbon expulsion from the source rock.