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. 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.

  3. Greenhouse gases dissolved in soil solution - often ignored, but important?

    NASA Astrophysics Data System (ADS)

    Weymann, Daniel; Brueggemann, Nicolas; Puetz, Thomas; Vereecken, Harry

    2014-05-01

    Flux measurements of climate-relevant trace gases from soils are frequently undertaken in contemporary ecosystem studies and substantially contribute to our understanding of greenhouse gas balances of the biosphere. While the great majority of such investigations builds on closed chamber and eddy covariance measurements, where upward gas fluxes to the atmosphere are measured, fewest concurrently consider greenhouse gas dissolution in the seepage and leaching of dissolved gases via the vadose zone to the groundwater. Here we present annual leaching losses of dissolved N2O and CO2 from arable, grassland, and forest lysimeter soils from three sites differing in altitude and climate. We aim to assess their importance in comparison to direct N2O emission, soil respiration, and further leaching parameters of the C- and N cycle. The lysimeters are part of the Germany-wide lysimeter network initiative TERENO-SoilCan, which investigates feedbacks of climate change to the pedosphere on a long-term scale. Soil water samples were collected weekly from different depths of the profiles by means of suction cups. A laboratory pre-experiment proved that no degassing occurred under those sampling conditions. We applied the headspace equilibration technique to determine dissolved gas concentrations by gas chromatography. The seepage water of all lysimeters was consistently supersaturated with N2O and CO2 compared to water equilibrated ambient air. In terms of N2O, leaching losses increased in the ascending order forest, grassland, and arable soils, respectively. In case of the latter soils, we observed a strong variability of N2O, with dissolved concentrations up to 23 ?g N L-1. However, since seepage discharge of the arable lysimeters was comparatively small and mostly limited to the hydrological winter season, leached N2O appeared to be less important than direct N2O emissions. In terms of dissolved CO2,our measurements revealed considerable leaching losses from the mountainous forest and grassland soils, based on concentrations up to 24 mg C L-1 and high seepage discharge. Such losses turned out to be similarly important like soil respiration, particularly during winter when temperature-dependent soil respiration declined. In conclusion, the results of the first year of our measurements provide evidence that dissolved greenhouse gases should be considered in studies which aim to assess full greenhouse gas balances, particularly in ecosystems where hydrological conditions favour microbial activity and high leaching losses.

  4. Radiation interactions in high-pressure gases

    SciTech Connect

    Christophorou, L.G. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA))

    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.

  5. 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.

  6. Ring whirl radiative structures after laser breakdown in noble gases

    SciTech Connect

    Filippov, A. V.; Mazalov, D. A.; Pal', A. F.; Rasskazova, V. V.; Rogachev, V. G.; Starostin, A. N.; Shaporenko, A. M. [Troitsk Institute for Innovation and Fusion Research, TRINITI, 142092, Troitsk, Moscow Region (Russian Federation)

    1997-04-15

    It was found experimentally that after breakdown of Q-switched Nd-YAG laser beam in noble gases the toroidal radiative formations shaped from initial spherical region of hot luminous gas. Schlieren and interferometric examinations reveal the existence of nonuniformity in energy input at early spark stage and following formation of the whirl ring structure after the produced shock wave has gone away. The results of numerical modelling of gas dynamical flow arising in Ar after inhomogeneous energy input imitating laser breakdown in real conditions are in qualitative agreement with the observed picture.

  7. Radiative precursors driven by converging blast waves in noble gases

    SciTech Connect

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; Grouchy, P. de; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L. [Blackett Laboratory, Imperial College London SW7 2BW (United Kingdom)] [Blackett Laboratory, Imperial College London SW7 2BW (United Kingdom); Williams, R. J. R. [Atomic Weapons Establishment, Aldermaston RG7 4PR (United Kingdom)] [Atomic Weapons Establishment, Aldermaston RG7 4PR (United Kingdom); Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States)] [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States); and others

    2014-03-15

    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20?km s{sup ?1} blast waves through gases of densities of the order 10{sup ?5} g cm{sup ?3} (see Burdiak et al. [High Energy Density Phys. 9(1), 52–62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  8. Radiative precursors driven by converging blast waves in noble gases

    NASA Astrophysics Data System (ADS)

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; de Grouchy, P.; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L.; Williams, R. J. R.; Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W.; Rosenberg, E.; Schrafel, P.; Kusse, B.

    2014-03-01

    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20 km s-1 blast waves through gases of densities of the order 10-5 g cm-3 (see Burdiak et al. [High Energy Density Phys. 9(1), 52-62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  9. Gage measures total radiation, including vacuum UV, from ionized high-temperature gases

    NASA Technical Reports Server (NTRS)

    Wood, A. D.

    1969-01-01

    Transient-heat transfer gage measures the total radiation intensity from vacuum ultraviolet and ionized high temperature gases. The gage includes a sensitive piezoelectric crystal that is completely isolated from any ionized flow and vacuum ultraviolet irradiation.

  10. TRADEOFFs in climate effects through aircraft routing: forcing due to radiatively active gases

    NASA Astrophysics Data System (ADS)

    Stordal, F.; Gauss, M.; Myhre, G.; Mancini, E.; Hauglustaine, D. A.; Köhler, M. O.; Berntsen, T.; . G Stordal, E. J.; Iachetti, D.; Pitari, G.; Isaksen, I. S. A.

    2006-10-01

    We have estimated impacts of alternative aviation routings on the radiative forcing. Changes in ozone and OH have been estimated in four Chemistry Transport Models (CTMs) participating in the TRADEOFF project. Radiative forcings due to ozone and methane have been calculated accordingly. In addition radiative forcing due to CO2 is estimated based on fuel consumption. Three alternative routing cases are investigated; one scenario assuming additional polar routes and two scenarios assuming aircraft cruising at higher (+2000 ft) and lower (-6000 ft) altitudes. Results from the base case in year 2000 are included as a reference. Taking first a steady state backward looking approach, adding the changes in the forcing from ozone, CO2 and CH4, the ranges of the models used in this work are -0.8 to -1.8 and 0.3 to 0.6 m Wm-2 in the lower (-6000 ft) and higher (+2000 ft) cruise levels, respectively. In relative terms, flying 6000ft lower reduces the forcing by 5-10% compared to the current flight pattern, whereas flying higher, while saving fuel and presumably flying time, increases the forcing by about 2-3%. Taking next a forward looking approach we have estimated the integrated forcing (m Wm-2 yr) over 20 and 100 years time horizons. The relative contributions from each of the three climate gases are somewhat different from the backward looking approach. The differences are moderate adopting 100 year time horizon, whereas under the 20 year horizon CO2 naturally becomes less important relatively. Thus the forcing agents impact climate differently on various time scales. Also, we have found significant differences between the models for ozone and methane. We conclude that we are not yet at a point where we can include non-CO2 effects of aviation in emission trading schemes. Nevertheless, the rerouting cases that have been studied here yield relatively small changes in the radiative forcing due to the radiatively active gases.

  11. Greenhouse Gases in Intensive Agriculture: Contributions of Individual Gases to the Radiative Forcing of the Atmosphere

    Microsoft Academic Search

    G. Philip Robertson; Eldor A. Paul; Richard R. Harwood

    2000-01-01

    Agriculture plays a major role in the global fluxes of the greenhouse gases carbon dioxide, nitrous oxide, and methane. From 1991 to 1999, we measured gas fluxes and other sources of global warming potential (GWP) in cropped and nearby unmanaged ecosystems. Net GWP (grams of carbon dioxide equivalents per square meter per year) ranged from 110 in our conventional tillage

  12. 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.

  13. 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.

  14. 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

  15. Unusual radiation effects from atoms in gases and plasmas* V. I. Savchenko

    E-print Network

    Unusual radiation effects from atoms in gases and plasmas* V. I. Savchenko and N. J. Fisch; accepted 13 January 1999 New interesting effects arise, when three-level atoms interact with the plasma, laser field, or a heat bath. If the atoms inside the plasma are excited by the polarized laser pulse

  16. Monte Carlo Simulation of Radiation in Gases with a NarrowBand Model

    E-print Network

    Dufresne, Jean-Louis

    Monte Carlo Simulation of Radiation in Gases with a Narrow­Band Model and a Net, Germany. published in ASME Journal of Heat Transfer, May 1996, pp.401­407 Abstract The Monte Carlo method with the Monte Carlo method : numerical efficiency becomes independent of optical thickness, strongly non uniform

  17. The Use of UV, Visible and Near IR Solar Back Scattered Radiation to Determine Trace Gases

    NASA Astrophysics Data System (ADS)

    Richter, Andreas; Wagner, Thomas

    Satellite remote sensing in the near-IR, visible and UV spectral range makes use of absorption and emission processes of electromagnetic radiation corresponding to electronic transitions, combined with simultaneous rotational-vibrational molecular transitions. One important difference compared to atmospheric observations in the microwave and thermal IR spectral range is that, usually thermal emission can be neglected at short wavelengths (there might, however, be emissions from, for example, excited gases in the high atmosphere). Thus the observed spectral signatures can be directly related to absorption spectra of atmospheric constituents. The neglect of emission terms makes the spectral analysis in the UV/vis spectral range usually reasonably straight forward. Another important and related advantage is that from satellite observations in the UV/vis spectral region, information from all atmospheric height layers (including the near surface layers) can be obtained. This makes UV/vis satellite observations a powerful tool for the monitoring of atmospheric pollution and for the characterisation and quantification of emission sources which are usually located close to the ground. It should, however, also be noted that, in contrast to observations in the microwave or thermal IR, usually little or no information on the vertical distribution of a trace gas is obtained.

  18. ARTICLES: Self-focusing of laser radiation in molecular gases

    Microsoft Academic Search

    Aleksei I. Osipov; Vladislav Ya Panchenko; A. A. Filippov

    1985-01-01

    Self-focusing and self-defocusing of CO2 laser pulses of 1.6 to 80 nsec duration was observed in SF6 gas for several lines in the 10P branch. It was observed that self-focusing depends on the vibrational excitation of the molecules and on their distribution function. This new self-focusing mechanism may be useful for propagation of high-power laser radiation in the atmosphere. Bibtex

  19. Important Atomic, Molecular and Radiative Processes in Low Pressure Discharge Lamps

    NASA Astrophysics Data System (ADS)

    Lister, Graeme G.

    2007-08-01

    Low pressure discharges are used in a number of light sources, of which the most important application for general lighting is the fluorescent lamp (FL). In conventional FL, electrical energy is converted to UV radiation through excitation of mercury atoms; the UV is then converted to visible radiation using a phosphor. Other atomic radiators, such as sodium and rare gases, are used for applications but are unsuitable for general lighting. In recent years, there has been strong interest in finding alternative atomic and molecular radiators and research is continuing. The efficiency of producing light in a low pressure discharge depends on the balance between ionization processes, which sustain the plasma, and the excitation of atoms or molecules into radiating states through electron impact excitation and collisions between atoms in excited states. Since radiation emitted at one point in the discharge may be absorbed and re-emitted several times before it finally reaches the wall, radiation transport also plays a significant role in determining the fraction of electrical energy which is converted to radiation. Numerical models can help guide the development of more efficient light sources, but there is currently a lack of data for a number of important fundamental processes. This paper will describe the important physical processes in low pressure discharge light sources, and discuss the requirements for new and improved atomic and molecular data.

  20. Application of the full spectrum correlated- k distribution approach to modeling non-gray radiation in combustion gases

    Microsoft Academic Search

    Sandip Mazumder; Michael F. Modest

    2002-01-01

    The treatment of radiative transport through combustion gases is rendered extremely difficult by the strong spectral variation of the absorption coefficients of molecular gases. In the full spectrum correlated-k distribution (FSCK) approach, a transformation is invoked, whereby the radiative transfer equation (RTE) is transformed from wavenumber to non-dimensional Planck-weighted wavenumber space after reordering of the spectrum. The reordering results in

  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

    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.

  2. Laser driven high energy density radiative blast waves launched in clustered gases

    NASA Astrophysics Data System (ADS)

    Olsson-Robbie, Stefan; Doyle, Hugo; Lowe, Hazel; Price, Chris; Bigourd, Damien; Patankar, Siddharth; Mecseki, Katalin; Booth, Nicola; Scott, Robbie; Moore, Alastair; Hohenberger, Matthias; Rodriguez, Rafael; Gumbrell, Edward; Symes, Daniel; Smith, Roland

    2012-10-01

    Intense lasers deposit energy efficiently in clustered gases creating hot plasma with low density, conditions ideal for launching radiative blast waves (BWs) of interest for laboratory astrophysics (LA). We report measurements in a range of gases irradiated by the Astra-Gemini laser with energies >10J. Optical imaging, self emission and temporally resolved x-ray spectra are used to characterise BW evolution. The high repetition rate of the laser allows us to explore the influence of atomic number and density on the BW dynamics. Altering the emitted radiation and opacity of the medium has a strong effect on the BW profile and energy loss. Strongly radiative BWs exhibit shell thinning, increasing their susceptibility to instabilities. We have demonstrated the onset of a velocity instability, driven by the exchange of energy between the shock and precursor in krypton BWs. We discuss the threshold conditions for this behaviour and the potential to study spatial shock front instabilities. Our results will be compared to simulations and analytical calculations with a view to designing scalable LA experiments.

  3. Study of multi-dimensional radiative energy transfer in molecular gases

    NASA Technical Reports Server (NTRS)

    Liu, Jiwen; Tiwari, S. N.

    1993-01-01

    The Monte Carlo method (MCM) is applied to analyze radiative heat transfer in nongray gases. The nongray model employed is based on the statistical arrow band model with an exponential-tailed inverse intensity distribution. Consideration of spectral correlation results in some distinguishing features of the Monte Carlo formulations. Validation of the Monte Carlo formulations has been conducted by comparing results of this method with other solutions. Extension of a one-dimensional problem to a multi-dimensional problem requires some special treatments in the Monte Carlo analysis. Use of different assumptions results in different sets of Monte Carlo formulations. The nongray narrow band formulations provide the most accurate results.

  4. Studying radiative shocks using laser driven blast waves in clustered gases

    NASA Astrophysics Data System (ADS)

    Symes, D. R.; Hohenberger, M.; Doyle, H. W.; Smith, R. A.; Moore, A. S.; Gumbrell, E. T.; Rodriguez, R.; Gil, J. M.

    2011-10-01

    We report on the creation of radiative blast waves by irradiating gases of atomic clusters with intense short pulse laser light. The efficient absorption of the cluster medium leads to high energy deposition and development into a cylindrical shock. These non-equilibrium, optically thin shocks have great potential for hydrodynamic scaling with astrophysical relevance, particularly for supernova remnants. We discuss how cluster blast waves may become susceptible to spatial and temporal instabilities and the application of the RAPCAL atomic physics code to determine our plasma conditions.

  5. 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.

  6. Third-harmonic and fourth-harmonic generations of CO2 laser radiation in a GaSe crystal

    Microsoft Academic Search

    Yanzhao Lu; Xinbing Wang; Liang Miao; Duluo Zuo; Zuhai Cheng

    2011-01-01

    Tunable third-harmonic and fourth-harmonic generations of pulsed CO2 laser radiation in a GaSe crystal were demonstrated. The optical properties of GaSe and phase-matching conditions in harmonic generations were investigated. The output peak powers for 3.2 mum and 2.4 mum were measured to be 1500 W and 320 W, with corresponding conversion efficiency from 9.6 mum of 0.1% and 0.02%, respectively.

  7. Third-harmonic and fourth-harmonic generations of CO 2 laser radiation in a GaSe crystal

    Microsoft Academic Search

    Yanzhao Lu; Xinbing Wang; Liang Miao; Duluo Zuo; Zuhai Cheng

    2011-01-01

    Tunable third-harmonic and fourth-harmonic generations of pulsed CO2 laser radiation in a GaSe crystal were demonstrated. The optical properties of GaSe and phase-matching conditions in harmonic generations were investigated. The output peak powers for 3.2?m and 2.4?m were measured to be 1500W and 320W, with corresponding conversion efficiency from 9.6?m of 0.1% and 0.02%, respectively.

  8. Impact of Radiatively Active Trace Gases on Long-Term Changes in the Middle Atmosphere

    NASA Astrophysics Data System (ADS)

    Qian, L.; Marsh, D. R.; Merkel, A. W.; Solomon, S. C.

    2014-12-01

    We conduct model simulations to examine how changes in concentration of radiatively active trace gases affect long-term changes in the middle atmosphere. We focus our model study on the impact of increases in carbon dioxide and methane, and decreases in ozone, between 1983 and 2003. The increase of carbon dioxide can cool the middle atmosphere through infrared emission at 15 microns, ozone depletion can cause cooling in the stratosphere and mesosphere through reduced solar heating, whereas the enhancement of methane, which increases water vapor, can introduce a cooling through reduced chemical heating or a warming through increased solar heating. We investigate the effect of each gas separately as well as the combined effect, using the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM).

  9. 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.

  10. An alternative to radiative forcing for estimating the relative importance of climate change mechanisms

    Microsoft Academic Search

    Keith P. Shine; Jolene Cook; Eleanor J. Highwood; Manoj M. Joshi

    2003-01-01

    Radiative forcing is widely used to measure the relative efficacy of climate change mechanisms. Earlier general circulation model (GCM) experiments showed that the global-mean radiative forcing could be used to predict, with useful accuracy, the consequent global-mean surface temperature change regardless of whether the forcing was due to, for example, changes in greenhouse gases or solar output. More recent experiments

  11. The importance of radiation quality for optimisation in radiology.

    PubMed

    Martin, Cj

    2007-04-01

    Selection of the appropriate radiation quality is an important aspect of optimisation for every clinical imaging task in radiology, since it affects both image quality and patient dose. Spreadsheet calculations of attenuation and absorption have been applied to basic imaging tasks to provide an assessment of imaging performance for a selection of phosphors used in radiology systems. Contrast, which is an important component of image quality affected by radiation quality, has been assessed in terms of the contrast to noise ratio (CNR) for a variety of X-ray beams. Both CNR and patient dose fall with tube potential, and selection of the best option is a compromise that will provide an adequate level of image quality with as low a radiation dose as practicable. It is important that systems are set up to match the response of the imaging phosphor, as there are significant differences between phosphors. For example, the sensitivity of barium fluorohalides used in computed radiography declines at higher tube potentials, whereas that of gadolinium oxysulphide used in rare earth screens increases. Addition of 0.2 mm copper filters, which can reduce patient entrance surface dose by 50%, may be advantageous for many applications in radiography and fluoroscopy. The disadvantage of adding copper is that tube output levels have to be increased. Application of simple calculations of the type employed here could prove useful for investigating and assessing the implications of potential changes in X-ray beam quality prior to implementation of new techniques. PMID:21614278

  12. Importance of Bladder Radioactivity for Radiation Safety in Nuclear Medicine

    PubMed Central

    Gültekin, Salih Sinan; ?ahmaran, Turan

    2013-01-01

    Objective: Most of the radiopharmaceuticals used in nuclear medicine are excreted via the urinary system. This study evaluated the importance of a reduction in bladder radioactivity for radiation safety. Methods: The study group of 135 patients underwent several organ scintigraphies [40/135; thyroid scintigraphy (TS), 30/135; whole body bone scintigraphy (WBS), 35/135; myocardial perfusion scintigraphy (MPS) and 30/135; renal scintigraphy (RS)] by a technologist within 1 month. In full and empty conditions, static bladder images and external dose rate measurements at 0.25, 0.50, 1, 1.5 and 2 m distances were obtained and decline ratios were calculated from these two data sets. Results: External radiation dose rates were highest in patients undergoing MPS. External dose rates at 0.25 m distance for TS, TKS, MPS and BS were measured to be 56, 106, 191 and 72 ?Sv h-1 for full bladder and 29, 55, 103 and 37 ?Sv h-1 for empty bladder, respectively. For TS, WBS, MPS and RS, respectively, average decline ratios were calculated to be 52%, 55%, 53% and 54% in the scintigraphic assessment and 49%, 51%, 49%, 50% and 50% in the assessment with Geiger counter. Conclusion: Decline in bladder radioactivity is important in terms of radiation safety. Patients should be encouraged for micturition after each scintigraphic test. Spending time together with radioactive patients at distances less than 1 m should be kept to a minimum where possible. Conflict of interest:None declared. PMID:24416625

  13. Generation of tunable hypersonic phonons from two-dimensional electron gases under free-electron laser radiations

    Microsoft Academic Search

    W. Xu; C. Zhang

    1998-01-01

    A theoretical study of generation of high-frequency acoustic-phonon emission by electrons in GaAs-based two-dimensional electron gases (2DEGs), subject to terahertz (THz) free-electron laser radiations, is presented. We have studied the frequency and angular distribution of the phonon emission generated optically via deformation potential coupling. The distinctive nature for electron-photon-phonon interactions in a 2DEG results in a strong dependence of the

  14. 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.

  15. 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.

  16. Future climate impacts of direct radiative forcing of anthropogenic aerosols, tropospheric ozone, and long-lived greenhouse gases

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

    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) II'. 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-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.

  17. Theoretical analysis and simulations of strong terahertz radiation from the interaction of ultrashort laser pulses with gases

    NASA Astrophysics Data System (ADS)

    Chen, Min; Pukhov, Alexander; Peng, Xiao-Yu; Willi, Oswald

    2008-10-01

    Terahertz (THz) radiation from the interaction of ultrashort laser pulses with gases is studied both by theoretical analysis and particle-in-cell (PIC) simulations. A one-dimensional THz generation model based on the transient ionization electric current mechanism is given, which explains the results of one-dimensional PIC simulations. At the same time the relation between the final THz field and the initial transient ionization current is shown. One- and two-dimensional simulations show that for the THz generation the contribution of the electric current due to ionization is much larger than the one driven by the usual ponderomotive force. Ionization current generated by different laser pulses and gases is also studied numerically. Based on the numerical results we explain the scaling laws for THz emission observed in the recent experiments performed by Xie [Phys. Rev. Lett. 96, 075005 (2006)]. We also study the effective parameter region for the carrier envelop phase measurement by the use of THz generation.

  18. An alternative to radiative forcing for estimating the relative importance of climate change mechanisms

    NASA Astrophysics Data System (ADS)

    Shine, Keith P.; Cook, Jolene; Highwood, Eleanor J.; Joshi, Manoj M.

    2003-10-01

    Radiative forcing is widely used to measure the relative efficacy of climate change mechanisms. Earlier general circulation model (GCM) experiments showed that the global-mean radiative forcing could be used to predict, with useful accuracy, the consequent global-mean surface temperature change regardless of whether the forcing was due to, for example, changes in greenhouse gases or solar output. More recent experiments indicate that for changes in absorbing aerosols and ozone, the predictive ability of radiative forcing is much worse. Building on a suggestion from Hansen and co-workers, we propose an alternative, the ``adjusted troposphere and stratosphere forcing''. We present GCM calculations showing that it is a significantly more reliable predictor of this GCM's surface temperature change than radiative forcing. It is a candidate to supplement radiative forcing as a metric for comparing different mechanisms and provides a framework for understanding the circumstances in which radiative forcing is less reliable.

  19. The importance of radiative transfer in stellar pulsation models

    SciTech Connect

    Davis, C.G.

    1992-01-01

    With the advent of the new astrophysical opacities it seems appropriate to discuss the need for a full radiative transfer (RT) theory instead of the usual equilibrium diffusion theory used in most nonlinear pulsation codes. Early studies on the importance of RT in the calculation of light curves for Cepheid models showed little effect over diffusion theory. The new opacities though may help to explain the bump'' mass discrepancy problem. For RR Lyrae models the use of RT theory causes some effects both in the color differences (U-B) as well as the light curves. New opacities help to explain the period ratios for double mode RR Lyrae and beat Cepheids. A new area of research is in the modeling of stars with high luminosity to mass ratios that show tendencies for doubling and transitions to chaos, such as W Virginis and RV Tauri stars. For these stars it has been shown the RT is necessary in calculating their light curves and that the understanding of the shock dynamics depends on the transfer of lines in the pulsating RT dependent atmospheres.

  20. The importance of radiative transfer in stellar pulsation models

    SciTech Connect

    Davis, C.G.

    1992-03-01

    With the advent of the new astrophysical opacities it seems appropriate to discuss the need for a full radiative transfer (RT) theory instead of the usual equilibrium diffusion theory used in most nonlinear pulsation codes. Early studies on the importance of RT in the calculation of light curves for Cepheid models showed little effect over diffusion theory. The new opacities though may help to explain the ``bump`` mass discrepancy problem. For RR Lyrae models the use of RT theory causes some effects both in the color differences (U-B) as well as the light curves. New opacities help to explain the period ratios for double mode RR Lyrae and beat Cepheids. A new area of research is in the modeling of stars with high luminosity to mass ratios that show tendencies for doubling and transitions to chaos, such as W Virginis and RV Tauri stars. For these stars it has been shown the RT is necessary in calculating their light curves and that the understanding of the shock dynamics depends on the transfer of lines in the pulsating RT dependent atmospheres.

  1. TRADEOFFs in climate effects through aircraft routing: forcing due to radiatively active gases

    Microsoft Academic Search

    F. Stordal; M. Gauss; G. Myhre; E. Mancini; D. A. Hauglustaine; M. O. Köhler; T. Berntsen; E. J.. G Stordal; D. Iachetti; G. Pitari; I. S. A. Isaksen

    2006-01-01

    We have estimated impacts of alternative aviation routings on the radiative forcing. Changes in ozone and OH have been estimated in four Chemistry Transport Models (CTMs) participating in the TRADEOFF project. Radiative forcings due to ozone and methane have been calculated accordingly. In addition radiative forcing due to CO2 is estimated based on fuel consumption. Three alternative routing cases are

  2. 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.

  3. GaSe and GaTe anisotropic layered semiconductors for radiation detectors

    Microsoft Academic Search

    Krishna C. Mandal; Michael Choi; Sung Hoon Kang; R. David Rauh; Jiuan Wei; Hui Zhang; Lili Zheng; Y. Cui; M. Groza; A. Burger

    2007-01-01

    High quality detector grade GaSe and GaTe single crystals have been grown by a modified vertical Bridgman technique using high purity Ga (7N) and in-house zone refined (ZR) precursor materials (Se and Te). A state-of-the-art computer model, MASTRAPP, is used to model heat and mass transfer in the Bridgman growth system and to predict the stress distribution in the as-grown

  4. The importance and unique aspects of radiation protection in medicine.

    PubMed

    Holmberg, Ola; Czarwinski, Renate; Mettler, Fred

    2010-10-01

    Radiation protection in medicine has unique aspects and is an essential element of medical practice. Medical uses of radiation occur throughout the world, from large cities to rural clinics. It has been estimated that the number of medical procedures using radiation grew from about 1.7 billion in 1980 to almost 4 billion in 2007. In spite of these large numbers, there are many parts of the world without adequate equipment, where the ability to perform additional medical procedures would likely result in a net benefit. Medicine accounts for more than 99.9% of the per caput effective dose from man-made sources. The goal in medical exposure is not to give the lowest dose, but to provide the correct dose to enable the practitioner to make the diagnosis or cure a tumour. Too little or too much dose is problematic and the risk of any given procedure ranges from negligible to potentially fatal. Radiation protection in medicine must deal with the issues of not having dose limits, purposely exposing sensitive subgroups, and purposely using doses that could cause deterministic effects. Radiation accidents involving medical uses have accounted for more acute radiation deaths than from any other source including Chernobyl. Many physicians have little or no training in radiation protection, and many have no qualified medical physics support. In many countries, medical radiation devices and uses are only minimally regulated and the rapidly evolving technology is a challenge. Medicine also accounts for the largest number of occupationally exposed workers and collective dose. PMID:20638808

  5. Atmospheric radiation

    SciTech Connect

    Harshvardhan, M.R. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

    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.

  6. Manure Gases

    MedlinePLUS

    ... The gases of most concern are ammonia and hydrogen sulfide. Other gases of concern include methane and ... present? Since most of these gases in particular hydrogen sulfide are heavier-than-air, they tend to ...

  7. 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.

  8. 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.

  9. Vacuum ultraviolet radiation of a hollow-cathode discharge in a flow of inert gases

    SciTech Connect

    Gabrielyan, Y.K.; Nersisyan, G.T.; Papanyan, V.O.

    1983-09-01

    The intensities of the VUV lines of helium, krypton, and xenon in a hollow-cathode discharge are investigated experimentally as a function of the discharge parameters when there is a longitudinal flow of gas through the hollow cathode. The hollow-cathode mode of operation is obtained for different pressures in the gas flow at lower supply voltages than in a stationary gas, which indicates that the hollow cathode is more effective in a flow. Using a collisional-radiational model, calculations of the populations of the low-lying singlet levels of helium and the intensities of the 60.1-, 53.7-, 58.4-nm lines in this discharge as a function of the current agree quite well with experimental results. Intense radiation of the 60.1-nm 2/sup 1/S--1/sup 1/S dipole-forbidden radiative transition of helium was observed, which is due to the absence of reabsorption of this line and the high density of metastable states (approx.10/sup 11/ cm/sup -3/).

  10. Interaction of Microwave Radiation Undergoing Stochastic Phase Jumps with Plasmas or Gases

    SciTech Connect

    Karas', V.I.; Fainberg, Ya. B.; Alisov, A.F.; Artamoshkin, A.M.; Gavrilenko, I.V.; Mirny, V.I. [National Science Center Kharkov Institute of Physics and Technology, ul. Akademicheskaya 1, Kharkov, 61108 (Ukraine); Bingham, R. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 OQX (United Kingdom); Levchenko, V.D.; Potapenko, I.F. [Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Miusskaya pl. 4, Moscow, 125047 (Russian Federation); Lontano, M. ['Piero Caldirola' Istituto di Fisica del Plasma, Associazione Euratom-ENEA per la Fusione-CNR, Milan (Italy); Starostin, A.N. [Troitsk Institute for Innovation and Fusion Research, Troitsk, Moscow oblast, 142092 (Russian Federation)

    2005-09-15

    New types of beam-plasma devices generating intense stochastic microwave radiation in the interaction of electron beams with hybrid plasma waveguides were developed and put into operation at the National Science Center Kharkov Institute of Physics and Technology (Ukraine). The objective of the paper is to discuss the results of theoretical and experimental studies and numerical simulations of the normal and oblique incidence of linearly polarized electromagnetic waves on an interface between a vacuum and an overcritical plasma. The main results of the reported investigations are as follows: (i) for the parameter values under analysis, the transmission coefficient for microwaves with a stochastically jumping phase is one order of magnitude greater than that for a broadband regular electromagnetic wave with the same spectral density; (ii) the electrons are heated most efficiently by obliquely incident waves with a stochastically jumping phase and, in addition, the electron distribution function has a high-energy tail; and (iii) necessary conditions for gas breakdown and for the initiation of a microwave discharge in stochastic fields in a light source are determined. The anomalously large transmission coefficient for microwaves, the anomalous character of the breakdown conditions, the anomalous behavior of microwave gas discharges, and the anomalous nature of collisionless electron heating, are attributed to stochastic jumps in the phase of microwave radiation.

  11. Modeling radiation in particle clouds: On the importance of inter-particle radiation for pulverized solid fuel combustion

    E-print Network

    Haugen, Nils Erland L

    2014-01-01

    The importance of inter-particle radiation for clusters of gray and diffuse particles is investigated. The radiative cooling of each individual particle is found to vary strongly with its position in the cluster, and a mean radiative particle cooling term is proposed for single particle simulations of particle clusters or for high detail simulation, like Direct Numerical Simulations of small sub-volumes of large clusters of particles. Radiative cooling is shown to be important both for furnaces for coal gasification and coal combustion. Broadening the particle size distribution is found to have just a minor effect on the radiative particle cooling. This is particularly the case for large and dense particle clusters where there is essentially no effect of size distribution broadening at all. For smaller and more dilute particle clusters, the effect of distribution broadening is clear but still not dominant.

  12. 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,

  13. Laser ignition of combustible gases by radiative heating of small particles

    SciTech Connect

    Hills, P.C. (ICI Biospecialties, 57 Tourle Street, Mayfield, NSW 2304 (Australia)); Zhang, D.K.; Wall, T.F. (Dept. of Chemical Engineering, Univ. of Newcastle, NSW 2308 (Australia)); Samson, P.J. (BHP Research Newcastle Lab., P.O. Box 188, Wallsend, NSW 2287 (Australia))

    1992-12-01

    This article summarizes the ignition risks of laser power delivered by optical fiber to combustible atmospheres. Of six possible ignition mechanisms, the ignition of a combustible gas by a small optically heated body has been extensively investigated. Continuous-wave (CW) powers of 100 mW delivered by multimode optical fibers created explosion in combustible atmospheres. A numerical model of the ignition of a combustible gas by a small heated body on the exposed end of an optical fiber is developed. Important parameters include gas (type and concentration), particle (type, diameter, absorptivity, refractive index, reactivity, thermal capacity, density), optical fiber (core diameter and numerical aperture), and light (wavelength and power).

  14. GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/, Methane Observations from the Greenhouse gases1

    E-print Network

    Palmer, Paul

    the Greenhouse gases1 Observing SATellite: Validation and Model2 Comparison3 Robert Parker, 1 Hartmut Boesch, 1 the Japanese Greenhouse gases Observing SATellite5 (GOSAT) and compare observed spatial and temporal variations important anthropogenic greenhouse gas, with a radiative22 forcing that is comparable to CO2 over a 20-year

  15. 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...

  16. From Anti-greenhouse Effect of Solar Absorbers to Cooling Effect of Greenhouse Gases: A 1-D Radiative Convective Model Study

    NASA Astrophysics Data System (ADS)

    Shia, R.

    2012-12-01

    The haze layer in Titan's upper atmosphere absorbs 90% of the solar radiation, but is inefficient for trapping infrared radiation generated by the surface. Its existence partially compensates for the greenhouse warming and keeps the surface approximately 9°C cooler than would otherwise be expected from the greenhouse effect alone. This is the so called anti-greenhouse effect (McKay et al., 1991). This effect can be used to alleviate the warming caused by the increasing level of greenhouse gases in the Earth's atmosphere. A one-dimensional radiative convective model (Kasting et al., 2009 and references listed there) is used to investigate the anti-greenhouse effect in the Earth atmosphere. Increasing of solar absorbers, e.g. aerosols and ozone, in the stratosphere reduces the surface solar flux and cool the surface. However, the absorption of the solar flux also increases the temperature in the upper atmosphere, while reduces the temperature at the surface. Thus, the temperature profile of the atmosphere changes and the regions with positive vertical temperature gradient are expanded. According to Shia (2010) the radiative forcing of greenhouse gases is directly related to the vertical temperature gradient. Under the new temperature profile increases of greenhouse gases should have less warming effect. When the solar absorbers keep increasing, eventually most of the atmosphere has positive temperature gradient and increasing greenhouse gases would cool the surface (Shia, 2011). The doubling CO2 scenario in the Earth atmosphere is simulated for different levels of solar absorbers using the 1-D RC model. The model results show that if the solar absorber increases to a certain level that less than 50% solar flux reaching the surface, doubling CO2 cools the surface by about 2 C. This means if the snowball Earth is generated by solar absorbers in the stratosphere, increasing greenhouse gases would make it freeze even more (Shia, 2011). References: Kasting, J. et al. 2009, http://vpl.astro.washington.edu/sci/AntiModels/models09.html McKay, C.P. et al. 1991, Titan: Greenhouse and Anti-greenhouse Effects on Titan. Science 253 (5024), 1118-21 Shia, R. 2011, Climate Effect of Greenhouse Gas: Warming or Cooling is Determined by Temperature Gradient, American Geophysical Union, Fall Meeting 2012, abstract #A51A-0274 Shia, R. 2010, Mechanism of Radiative Forcing of Greenhouse Gas and its Implication to the Global Warming, American Geophysical Union, Fall Meeting 2010, abstract #A11J-02

  17. 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.

  18. int. j. radiat. biol 2002, vol. 78, no. 12, 1065 1067 Routine screening mammography: how important is the radiation-

    E-print Network

    Brenner, David Jonathan

    int. j. radiat. biol 2002, vol. 78, no. 12, 1065± 1067 Routine screening mammography: how important associated with routine screening lower-energy X-rays is that they set in motion slower mammography, in terms mammography (26­30 kVp) are In this regard, Frankenberg et al. (2002) reportedexpected to be more hazardous

  19. 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.

  20. 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.

  1. The importance of the diurnal and annual cycle of air traffic for contrail radiative forcing.

    PubMed

    Stuber, Nicola; Forster, Piers; Rädel, Gaby; Shine, Keith

    2006-06-15

    Air traffic condensation trails, or contrails, are believed to have a net atmospheric warming effect, although one that is currently small compared to that induced by other sources of human emissions. However, the comparably large growth rate of air traffic requires an improved understanding of the resulting impact of aircraft radiative forcing on climate. Contrails have an effect on the Earth's energy balance similar to that of high thin ice clouds. Their trapping of outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) is partly compensated by their reflection of incoming solar radiation (negative radiative forcing). On average, the longwave effect dominates and the net contrail radiative forcing is believed to be positive. Over daily and annual timescales, varying levels of air traffic, meteorological conditions, and solar insolation influence the net forcing effect of contrails. Here we determine the factors most important for contrail climate forcing using a sophisticated radiative transfer model for a site in southeast England, located in the entrance to the North Atlantic flight corridor. We find that night-time flights during winter (December to February) are responsible for most of the contrail radiative forcing. Night flights account for only 25 per cent of daily air traffic, but contribute 60 to 80 per cent of the contrail forcing. Further, winter flights account for only 22 per cent of annual air traffic, but contribute half of the annual mean forcing. These results suggest that flight rescheduling could help to minimize the climate impact of aviation. PMID:16778887

  2. Electronegative gases

    SciTech Connect

    Christophorou, L.G.

    1981-01-01

    Recent knowledge on electronegative gases essential for the effective control of the number densities of free electrons in electrically stressed gases is highlighted. This knowledge aided the discovery of new gas dielectrics and the tailoring of gas dielectric mixtures. The role of electron attachment in the choice of unitary gas dielectrics or electronegative components in dielectric gas mixtures, and the role of electron scattering at low energies in the choice of buffer gases for such mixtures is outlined.

  3. Photoionization in Gases

    Microsoft Academic Search

    R. N. Varney; L. B. Loeb

    1935-01-01

    The balanced space charge positive ion detector, used in the experiments on ionization by positive alkali ions has been used in the study of photoionization in gases. The following experiments were performed: (1) A hydrogen discharge tube, operated by either a 1000- or an 8000-volt transformer, was set up so that the radiation emitted could pass through a fluorite window

  4. Can the Infrared Radiation that Causes the Enhanced Greenhouse Effect Be Put to Better Use?

    Microsoft Academic Search

    Ron Zevenhoven

    2008-01-01

    Increasing levels of certain greenhouse gases (GHGs), most importantly CO2 in the earths atmosphere, lead to climate change and global warming as a result of these gases interacting with thermal infrared (TIR) radiation from earth to space. Here, the option of modifying this radiation is analyzed which would result in modified TIR radiation that would interact less with atmospheric CO2.

  5. Parameterization of the absorption of the H2O continuum, CO2, O2, and other trace gases in the Fu-Liou solar radiation program

    NASA Astrophysics Data System (ADS)

    Zhang, Feng; Zeng, Qingcun; Gu, Y.; Liou, K. N.

    2005-07-01

    The absorption properties of the water vapor continuum and a number of weak bands for H2O, O2, CO2, CO, N2O, CH4, and O3 in the solar spectrum are incorporated into the Fu-Liou radiation parameterization program by using the correlated k-distribution method (CKD) for the sorting of absorption lines. The overlap absorption of the H2O lines and the H2O continuum (2500 14500 cm-1) are treated by taking the two gases as a single-mixture gas in transmittance calculations. Furthermore, in order to optimize the computation efforts, CO2 and CH4 in the spectral region 2850 5250 cm-1 are taken as a new single-mixture gas as well. For overlap involving other absorption lines in the Fu-Liou spectral bands, the authors adopt the multiplication rule for transmittance computations under which the absorption spectra for two gases are assumed to be uncorrelated. Compared to the line-by-line (LBL) computation, it is shown that the errors in fluxes introduced by these two approaches within the context of the CKD method are small and less than 0.48% for the H2O line and continuum in the 2500 14500 cm-1solar spectral region, ˜1% for H2O (line)+H2O (continuum)+CO2+CH4 in the spectral region 2850 5250 cm-1,and ˜1.5% for H2O (line)+H2O (continuum)+O2 in the 7700 14500 cm-1 spectral region. Analysis also demonstrates that the multiplication rule over a spectral interval as wide as 6800 cm-1 can produce acceptable errors with a maximum percentage value of about 2% in reference to the LBL calculation. Addition of the preceding gases increases the absorption of solar radiation under all sky conditions. For clear sky, the increase in instantaneous solar absorption is about 9% 13% (˜12 W m-2) among which the H2O continuum produces the largest increase, while the contributions from O2 and CO2 rank second and third, respectively. In cloudy sky, the addition of absorption amounts to about 6 9 W m-2. The new, improved program with the incorporation of the preceding gases produces a smaller solar absorption in clouds due to the reduced solar flux reaching the cloud top.

  6. Zi-Wei Lin Oct 5, 2004 UAH / NASA Space Radiation Shielding Program, MS Determine Important Nuclear Fragmentation Processes

    E-print Network

    Lin, Zi-wei

    Zi-Wei Lin Oct 5, 2004 UAH / NASA Space Radiation Shielding Program, MS Determine Important Nuclear Fragmentation Processes for Space Radiation Protection in Human Space Explorations Why do we need to study? Conclusions Zi-Wei Lin University of Alabama in Huntsville/ NASA Space Radiation Shielding Program, MSFC #12

  7. On the degradation of a shock wave in high-current radiating discharges in gases at atmospheric pressure

    Microsoft Academic Search

    Yu. M. Grishin; N. P. Kozlov; V. V. Kuzenov

    1998-01-01

    A theoretical study is made of the features of the radiational-plasmadynamic processes occurring in pulsed high-current radiating\\u000a discharges in gaseous media at atmospheric pressure when a capacitive store is discharged across an extended interelectrode\\u000a gap L=10–100 cm. Discharges of this kind are efficaciously employed as radiation sources and generators of strong shock waves in\\u000a various scientific and practical applications [see

  8. Importance of tropospheric volcanic aerosol for indirect radiative forcing of climate

    NASA Astrophysics Data System (ADS)

    Schmidt, A.; Carslaw, K. S.; Mann, G. W.; Rap, A.; Pringle, K. J.; Spracklen, D. V.; Wilson, M.; Forster, P. M.

    2012-08-01

    Observations and models have shown that continuously degassing volcanoes have a potentially large effect on the natural background aerosol loading and the radiative state of the atmosphere. We use a global aerosol microphysics model to quantify the impact of these volcanic emissions on the cloud albedo radiative forcing under pre-industrial (PI) and present-day (PD) conditions. We find that volcanic degassing increases global annual mean cloud droplet number concentrations by 40% under PI conditions, but by only 10% under PD conditions. Consequently, volcanic degassing causes a global annual mean cloud albedo effect of -1.06 W m-2 in the PI era but only -0.56 W m-2 in the PD era. This non-equal effect is explained partly by the lower background aerosol concentrations in the PI era, but also because more aerosol particles are produced per unit of volcanic sulphur emission in the PI atmosphere. The higher sensitivity of the PI atmosphere to volcanic emissions has an important consequence for the anthropogenic cloud radiative forcing because the large uncertainty in volcanic emissions translates into an uncertainty in the PI baseline cloud radiative state. Assuming a -50/+100% uncertainty range in the volcanic sulphur flux, we estimate the annual mean anthropogenic cloud albedo forcing to lie between -1.16 W m-2 and -0.86 W m-2. Therefore, the volcanically induced uncertainty in the PI baseline cloud radiative state substantially adds to the already large uncertainty in the magnitude of the indirect radiative forcing of climate.

  9. Importance of tropospheric volcanic aerosol for indirect radiative forcing of climate

    NASA Astrophysics Data System (ADS)

    Schmidt, A.; Carslaw, K. S.; Mann, G. W.; Rap, A.; Pringle, K. J.; Spracklen, D. V.; Wilson, M.; Forster, P. M.

    2012-03-01

    Observations and models have shown that continuously degassing volcanoes have a potentially large effect on the natural background aerosol loading and the radiative state of the atmosphere. Here, we use a global aerosol microphysics model to quantify the impact of these volcanic emissions on the cloud albedo radiative forcing under pre-industrial (PI) and present-day (PD) conditions. We find that volcanic degassing increases global annual mean cloud droplet number concentrations by 40% under PI conditions, but by only 10% under PD conditions. Consequently, volcanic degassing causes a global annual mean cloud albedo effect of -1.06 W m-2 in the PI era but only -0.56 W m-2 in the PD era. This non-equal effect is explained partly by the lower background aerosol concentrations in the PI era, but also because more aerosol particles are produced per unit of volcanic sulphur emission in the PI atmosphere. The higher sensitivity of the PI atmosphere to volcanic emissions has an important consequence for the anthropogenic cloud radiative forcing because the large uncertainty in volcanic emissions translates into an uncertainty in the PI baseline cloud radiative state. Assuming a -50/+100% uncertainty range in the volcanic sulphur flux, we estimate the annual mean anthropogenic cloud albedo forcing to lie between -1.16 W m-2 and -0.86 W m-2. Therefore, the volcanically induced uncertainty in the PI baseline cloud radiative state substantially adds to the already large uncertainty in the magnitude of the indirect radiative forcing of climate.

  10. 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.

  11. Predictions of secondary neutrons and their importance to radiation effects inside the International Space Station

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.

    2001-01-01

    As part of a study funded by NASA MSFC to assess thecontribution of secondary particles in producing radiation damage to optoelectronics devices located on the International Space Station (IS), Monte Carlo calculations have been made to predict secondary spectra vs. shielding inside ISS modules and in electronics boxes attached on the truss (Armstrong and Colborn, 1998). The calculations take into account secondary neutron, proton, and charged pion production from the ambient galactic cosmic-ray (GCR) proton, trapped proton, and neutron albedo environments. Comparisons of the predicted neutron spectra with measurments made on the Mir space station and other spacecraft have also been made (Armstrong and Colborn, 1998). In this paper, some initial results from folding the predicted neutron spectrum inside ISS modules from Armstrong and Colborn (1998) with several types of radiation effects response functions related to electronics damage and astronaut-dose are given. These results provide an estimate of the practical importance of neutrons compared to protons in assessing radiation effects for the ISS. Also, the important neutron energy ranges for producing these effects have been estimated, which provides guidance for onboard neutron measurement requirements.

  12. Importance of tropospheric volcanic aerosol for indirect radiative forcing of climate

    NASA Astrophysics Data System (ADS)

    Schmidt, A.; Carslaw, K. S.; Mann, G.; Rap, A.; Pringle, K. J.; Spracklen, D. V.; Wilson, M.; Forster, P.

    2013-12-01

    Observations and models have shown that continuously degassing volcanoes have a potentially large effect on the natural background aerosol loading and the radiative state of the atmosphere. We use a global aerosol microphysics model to quantify the impact of these volcanic emissions on the cloud albedo radiative forcing under pre-industrial (PI) and present-day (PD) conditions. We find that volcanic degassing increases global annual mean cloud droplet number concentrations by 40% under PI conditions, but by only 10% under PD conditions. Consequently, volcanic degassing causes a global annual mean cloud albedo effect of -1.06 W m-2 in the PI era but only -0.56 W m-2 in the PD era. This non-equal effect is explained partly by the lower background aerosol concentrations in the PI era, but also because more aerosol particles are produced per unit of volcanic sulphur emission in the PI atmosphere. The higher sensitivity of the PI atmosphere to volcanic emissions has an important consequence for the anthropogenic cloud radiative forcing because the large uncertainty in volcanic emissions translates into an uncertainty in the PI baseline cloud radiative state. Assuming a -50/+100% uncertainty range in the volcanic sulphur flux, we estimate the annual mean anthropogenic cloud albedo forcing to lie between -1.16 W m-2 and -0.86 W m-2. Therefore, the volcanically induced uncertainty in the PI baseline cloud radiative state substantially adds to the already large uncertainty in the magnitude of the indirect radiative forcing of climate. Effect of uncertain volcanic sulphur emissions on the annual global mean cloud albedo effect and anthropogenic cloud albedo forcing. The grey and blue bars show the magnitude and the uncertainty range for the volcanic cloud albedo effect for present-day (PD) and pre-industrial (PI), respectively. In the central panel, the top red bar shows the magnitude of the anthropogenic cloud albedo forcing as estimated by IPCC based on a range of modelling studies using different aerosol species/mixtures. The red bar directly below it shows the magnitude of the anthropogenic cloud albedo forcing estimated in this study with the uncertainty range arising from the -50/+100% uncertainty in the volcanic source strength assuming the same volcanic flux strength over the PI-PD period. In the bottom panel, the dashed error bar shows the uncertainty range for the magnitude of the combined volcanic and anthropogenic cloud albedo forcing assuming a change in the volcanic sulphur flux strength over the PI-PD period.

  13. Gases in Seawater

    Microsoft Academic Search

    P. D. Nightingale; P. S. Liss

    2003-01-01

    The annual gross and net primary productivity of the surface oceans is similar in size to that on land (IPCC, 2001). Marine productivity drives the cycling of gases such as oxygen (O2), dimethyl sulfide (DMS), carbon monoxide (CO), carbon dioxide (CO2), and methyl iodide (CH3I) which are of fundamental importance in studies of marine productivity, biogeochemical cycles, atmospheric chemistry, climate,

  14. Measurement of Selected Organic Trace Gases During TRACE-P

    NASA Technical Reports Server (NTRS)

    Atlas, Elliot

    2004-01-01

    Major goals of the TRACE-P mission were: 1) to investigate the chemical composition of radiatively important gases, aerosols, and their precursors in the Asian outflow over the western Pacific, and 2) to describe and understand the chemical evolution of the Asian outflow as it is transported and mixed into the global troposphere. The research performed as part of this proposal addressed these major goals with a study of the organic chemical composition of gases in the TRACE-P region. This work was a close collaboration with the Blake/Rowland research group at UC-Irvine, and they have provided a separate report for their funded effort.

  15. A study of ambient upstream material properties using perpendicular laser driven radiative blast waves in atomic cluster gases

    NASA Astrophysics Data System (ADS)

    Olsson Robbie, S. I.; Doyle, H. W.; Symes, D. R.; Smith, R. A.

    2012-03-01

    We report on the characterisation of the upstream medium ahead of a radiative cylindrical blast wave launched in an argon cluster gas with a 1 J, 1 ps, 1054 nm Nd:Glass laser system. By launching two perpendicular blast waves and introducing a time delay between the heating beams it is possible to determine the extent of the cluster medium by observing the high energy absorption region associated with clusters, as apposed to the low energy deposition in monatomic gas. It was found that argon ions launched from the initial laser driven cluster ionisation created a ballistic ion wave which sweeps out ahead of the hydrodynamic blast wave at an initial velocity of 1000 kms -1. This ballistic wave disassembles the clusters ahead of the blast wave into a neutral gas medium before the arrival of a radiative precursor. This observation gives us confidence that the dynamics of a radiative blast wave in cluster based experiments is determined primarily by the properties of an upstream atomic gas, and is not significantly influenced by cluster affects on energy transport or other material properties.

  16. Determine Important Nuclear Fragmentation Processes for Space Radiation Protection in Human Space Explorations

    NASA Technical Reports Server (NTRS)

    Lin, Zi-wei

    2004-01-01

    Space radiation from cosmic ray particles is one of the main challenges for long-term human space explorations such as a permanent moon base or a trip to Mars. Material shielding may provide significant radiation protection to astronauts, and models have been developed in order to evaluate the effectiveness of different shielding materials and to predict radiation environment inside the spacecraft. In this study we determine the nuclear fragmentation cross sections which will most effect the radiation risk behind typical radiation shielding materials. These cross sections thus need more theoretical studies and accurate experimental measurements in order for us to more precisely predict the radiation risk in human space explorations.

  17. Determine Important Nuclear Fragmentation Processes for Space Radiation Protection in Human Space Explorations

    NASA Technical Reports Server (NTRS)

    Lin, Zi-Wei

    2004-01-01

    Space radiation from cosmic ray particles is one of the main challenges for long-term human space explorations such as a permanent moon base or a trip to Mars. Material shielding may provide significant radiation protection to astronauts, and models have been developed in order to evaluate the effectiveness of different shielding materials and to predict radiation environment inside the spacecraft. In this study we determine the nuclear fragmentation cross sections which will most affect the radiation risk behind typical radiation shielding materials. These cross sections thus need more theoretical studies and accurate experimental measurements in order for us to more precisely predict the radiation risk in human space explorations.

  18. Determine Important Nuclear Fragmentation Processes for Space Radiation Protection in Human Space Explorations

    NASA Technical Reports Server (NTRS)

    Lin, Zi-Wei

    2004-01-01

    Space radiation from cosmic ray particles is one of the main challenges for long-term human space explorations such as a permanent moon base or a trip to Mars. Material shielding may provide significant radiation protection to astronauts, and models have been developed in order to evaluate the effectiveness of different shielding materials and to predict radiation environment inside the spacecraft. In this study we determine the nuclear fragmentation cross sections which will most affect the radiation risk behind typical radiation shielding materials. These cross sections thus need more theoretical studies and accurate experimental measurements in order for us to more precisely predict the radiation risk in human space exploration.

  19. Study of defects, radiation damage and implanted gases in solids by field-ion and atom-probe microscopy

    SciTech Connect

    Seidman, D.N.; Amano, J.; Wagner, A.

    1980-10-01

    The ability of the field-ion microscope to image individual atoms has been applied, at Cornell University, to the study of fundamental properties of point defects in irradiated or quenched metals. The capability of the atom probe field-ion microscope to determine the chemistry - that is, the mass-to-charge ratio - of a single ion has been used to investigate the behavior of different implanted species in metals. A brief review is presented of: (1) the basic physical principles of the field-ion and atom-probe microscopes; (2) the many applications of these instruments to the study of defects and radiation damage in solids; and (3) the application of the atom-probe field-ion microscope to the study of the behavior of implanted /sup 3/He and /sup 4/He atoms in tungsten. The paper is heavily referenced so that the reader can pursue his specific research interests in detail.

  20. 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.

  1. 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.

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

    SciTech Connect

    Martinez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo, E-mail: j.m.sykora@astro.uio.no [Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA 94304 (United States)

    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.

  3. 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.

  4. 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.

  5. Agricultural ecosystem effects on trace gases and global climate change

    SciTech Connect

    Not Available

    1993-01-01

    Global climate change is an issue that has been thrust to the forefront of scientific, political, and general community interest. In the span of this human generation, the earth's climate is expected to change more rapidly than it has over any comparable period of recorded history. Some of the changes will result from natural processes, beyond human control, but much of this change is subject to anthropogenic influence arising from processes that are only beginning to be understood. Increasing concentrations of atmospheric radiatively active trace gases are being inadvertently affected by fossil fuel combustion; but other activities of industry, agriculture, forestry, changing land-use practices, waste disposal, and transportation also affect the chemical composition of the atmosphere. The measured and projected changes of the atmospheric concentrations of radiatively active trace gases have been modeled and estimated to predict changes in the global climate. Accuracy and reliability of these predictions are the subject of considerable debate among scientists and other concerned individuals, groups, and governmental agencies throughout the world. The objective of this book is to provide a review of current knowledge on the measurement of radiatively active trace gases in agricultural ecosystems and the effect of agriculture on the atmospheric concentrations of these gases. This book is compiled from written papers presented at a symposium entitled, Agroecosystem Effects on Radiatively Important Trace Gases and Global Climate Change, held at the American Society of Agronomy Meetings in Denver, CO, 27 Oct.-1 Nov. 1991. Fourteen chapters have been processed separately for inclusion in the appropriate data bases.

  6. Observation of greenhouse gases from ground-based telescope "Subaru" and "TAO"

    NASA Astrophysics Data System (ADS)

    Hayashi, Y.; Imasu, R.; Miyata, T.

    2009-12-01

    Long-term observation of greenhouse gases is very important to understand temporal variations of greenhouse gases. This January, Japanese satellite, GOSAT (greenhouse gases observing satellite) was launched and its operational observation has started. For supporting satellite observations, validation data such as obtained by ground-based observations are very important. However, there is no observation site in South America. In this study, I propose new data analysis procedure for the observation of greenhouse gases using a ground-based astronomical telescope, which is placed in South America. The purpose of this study is to measure the vertical distribution and temporal variation of greenhouse gases such as methane and ozone from infrared spectrum data measured by an astronomical telescope on the ground. Although solar radiation is generally used to measure greenhouse gases, we use stellar radiation in order to measure the gases even in the night. The method developed in this study can be applicable for analysis of the data observed at world wide astronomical observatories. Institute of Astronomy, The University of Tokyo has conducted an international project, TAO (University of Tokyo Atacama Observatory) Project. In this project they are constructing a very big size telescope (diameter of the main mirror is 6m) at the observation site in Chile, South America. We are going to measure greenhouse gases using the telescope. However, as it is still under construction, we use the data from another Japanese telescope, “Subaru” in Hawaii. Subaru telescope, which has 7 instruments, is located at the top of Mauna Kea, Hawaii. In this study, we use mid-infrared grating spectrometer, called COMICS. This instrument provides spectroscopic capabilities from 7.5-13.5 um, which include absorption bands methane and ozone. To analyze these greenhouse gases, we developed a new method using two stars which have different zenith angles observed in a short interval. I will present some preliminary results retrieved from Subaru data.

  7. 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.

  8. Protection from solar UV radiation - how important is what you wear and how you wear it?

    Microsoft Academic Search

    C. A. Wilson

    How fabric properties and conditions of wear affect UV transmission is reviewed and recommendations for manufacture and selection of sun protective garments are discussed. Exposure to ultraviolet (UV) radiation has been identified as the \\

  9. Thermocamera studies of gases and vapours.

    PubMed Central

    Carlsson, P; Ljungqvist, B; Neikter, K

    1982-01-01

    Most gases and vapours with a bipolar molecular structure absorb infrared energy. If such a gas is interposed between an object emitting infrared radiation and a thermocamera the gas will absorb some of the infrared radiation and thus cast a shadow on the thermocamera picture. In this assay it is possible to visualise the gas. This method had been used to study pollution with anaesthetic gases and vapours in operating theatres. The vapours of other chemicals used in hospitals and other places of work also have been studied. The method permits the study of dispersion and flow patterns of polluting gases and vapours during work. Images PMID:7093159

  10. 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

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

    PubMed

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

    2010-11-01

    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/m(2) to 11.6 mW/m(2) 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/m(2) for the air traffic in the year 2000. PMID:20974909

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

    E-print Network

    Laughlin, Robert B.

    Zevenhoven & 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 (Ponting, 1991, Göttlicher, 1999). So-called greenhouse gases (GHGs), most importantly carbon dioxide (CO2

  13. 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.

  14. Climate responses to direct radiative forcing of anthropogenic aerosols, tropospheric ozone, and long-lived greenhouse gases in eastern China over 1951-2000

    NASA Astrophysics Data System (ADS)

    Chang, Wenyuan; Liao, Hong; Wang, Huijun

    2009-07-01

    A unified chemistry-aerosol-climate model is applied in this work to compare climate responses to changing concentrations of long-lived greenhouse gases (GHGs, CO2, CH4, N2O), tropospheric O3, and aerosols during the years 1951-2000. Concentrations of sulfate, nitrate, primary organic carbon (POA), secondary organic carbon (SOA), black carbon (BC) aerosols, and tropospheric O3 for the years 1950 and 2000 are obtained a priori by coupled chemistry-aerosol-GCM simulations, and then monthly concentrations are interpolated linearly between 1951 and 2000. The annual concentrations of GHGs are taken from the IPCC Third Assessment Report. BC aerosol is internally mixed with other aerosols. Model results indicate that the simulated climate change over 1951-2000 is sensitive to anthropogenic changes in atmospheric components. The predicted year 2000 global mean surface air temperature can differ by 0.8°C with different forcings. Relative to the climate simulation without changes in GHGs, O3, and aerosols, anthropogenic forcings of SO{4/2-}, BC, BC+SO{4/2-}, BC+SO{4/2-}+POA, BC+SO{4/2-}+POA+SOA+NO{3/-}, O3, and GHGs are predicted to change the surface air temperature averaged over 1971-2000 in eastern China, respectively, by -0.40°C, +0.62°C, +0.18°C, +0.15°C, -0.78°C, +0.43°C, and +0.85°C, and to change the precipitation, respectively, by -0.21, +0.07, -0.03, +0.02, -0.24, -0.08, and +0.10 mm d-1. The authors conclude that all major aerosols are as important as GHGs in influencing climate change in eastern China, and tropospheric O3 also needs to be included in studies of regional climate change in China.

  15. 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.

  16. Determination of important nuclear fragmentation processes for human space radiation protection

    SciTech Connect

    Lin Ziwei [Mail Stop VP62, NSSTC, 320 Sparkman Drive, Huntsville, Alabama 35805 (United States)

    2007-03-15

    We present a semianalytical 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 for us to better predict, reduce, and mitigate the radiation exposure in human space explorations.

  17. On the importance of radiative heat exchange during nocturnal flight in birds.

    PubMed

    Léger, Jérôme; Larochelle, Jacques

    2006-01-01

    Many migratory flights take place during cloudless nights, thus under conditions where the sky temperature can commonly be 20 degrees C below local air temperature. The sky then acts as a radiative sink, leading objects exposed to it to have a lower surface temperature than unexposed ones because less infrared energy is received from the sky than from the surfaces that are isothermic to air. To investigate the significance of this effect for heat dissipation during nocturnal flight in birds, we built a wind tunnel with the facility to control wall temperature (TASK) and air temperature (TAIR) independently at air speeds (UWIN) comparable to flying speeds. We used it to measure the influence of TASK, TAIR and UWIN on plumage and skin temperatures in pigeons having to dissipate a thermal load while constrained at rest in a flight posture. Our results show that the temperature of the flight and insulation plumages exposed to a radiative sink can be accurately described by multiple regression models (r2>0.96) based only on TAIR, TASK and UWIN. Predictions based on these models indicate that while convection dominates heat loss for a plumage exposed to air moving at flight speed in a thermally uniform environment, radiation may dominate in the presence of a radiative sink comparable to a clear sky. Our data also indicate that reducing TASK to a temperature 20 degrees C below TAIR can increase the temperature difference across the exposed plumage by at least 13% and thus facilitate heat flow through the main thermal resistance to the loss of internally produced heat in birds. While extrapolation from our experimentally constrained conditions to free flight in the atmosphere is difficult, our results suggest that the sky temperature has been a neglected factor in determining the range of TAIR over which prolonged flight is possible. PMID:16354782

  18. On the importance of prompt oxygen changes for hypofractionated radiation treatments

    NASA Astrophysics Data System (ADS)

    Kissick, Michael; Campos, David; van der Kogel, Albert; Kimple, Randall

    2013-10-01

    This discussion is motivated by observations of prompt oxygen changes occurring prior to a significant number of cancer cells dying (permanently stopping their metabolic activity) from therapeutic agents like large doses of ionizing radiation. Such changes must be from changes in the vasculature that supplies the tissue or from the metabolic changes in the tissue itself. An adapted linear-quadratic treatment is used to estimate the cell survival variation magnitudes from repair and reoxygenation from a two-fraction treatment in which the second fraction would happen prior to significant cell death from the first fraction, in the large fraction limit. It is clear the effects of oxygen changes are likely to be the most significant factor for hypofractionation because of large radiation doses. It is a larger effect than repair. Optimal dose timing should be determined by the peak oxygen timing. A call is made to prioritize near real time measurements of oxygen dynamics in tumors undergoing hypofractionated treatments in order to make these treatments adaptable and patient-specific.

  19. 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.

  20. 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.

  1. Electrical breakdown of gases

    Microsoft Academic Search

    J. M. Meek; J. D. Craggs

    1978-01-01

    A collection of individual works on electrical discharges is presented. Topics covered include: fundamental processes in the electrical breakdown of gases; vacuum breakdown; spark breakdown in uniform fields; corona discharge; spark breakdown in non-uniform fields; breakdown voltage characteristics; irradiation and time lags; high-frequency breakdown of gases; laser-induced electrical breakdown of gases; spark channels; and electrode phenomena. (GHT)

  2. Some important issues in developing basic radiation protection recommendations: dosimetric aspects

    SciTech Connect

    Thomas, R.H.

    1984-03-01

    Some aspects of the difficulties encountered in the dose equivalent system used in radiation protection are explored and recent work to improve these deficiencies described. The philosophical advantages of a departure from the dose equivalent-based system and its replacement by a risk-based system are briefly discussed. The definition of dose equivalent and the debate concerning its physical dimensions and units are described. Dose equivalent is related to other physiological quantities in physics and the treatment of these quantities in the International System of Units compared. Practical problems in the determination of dose equivalent are illustrated using neutrons as an example. The proliferation of operational quantities for the evaluation of neutron dose equivalent and the concomitant potential for confusion when determinations of neutron dose equivalent are intercompared is described. The evaluation of fluence to dose equivalent conversion coefficients and methods of interpolation between recommended values are described. Particular emphasis is given to the accuracy and precision of dose equivalent estimation. Recent work of a Task Group of the ICRP to improve recommended conversion coefficients and the work of an ICRU committee to improve the definition of operational dose equivalent quantities is summarized. 125 references, 11 figures, 4 tables.

  3. 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.

  4. 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.

  5. 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 the radiative impacts of five species of greenhouse gases (CO2, CH4, N2O, CFC-11 and CFC-12) and sulfate

  6. 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.

  7. 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.

  8. 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.

  9. RNA Sequencing and Proteogenomics Reveal the Importance of Leaderless mRNAs in the Radiation-Tolerant Bacterium Deinococcus deserti

    PubMed Central

    de Groot, Arjan; Roche, David; Fernandez, Bernard; Ludanyi, Monika; Cruveiller, Stéphane; Pignol, David; Vallenet, David; Armengaud, Jean; Blanchard, Laurence

    2014-01-01

    Deinococcus deserti is a desiccation- and radiation-tolerant desert bacterium. Differential RNA sequencing (RNA-seq) was performed to explore the specificities of its transcriptome. Strikingly, for 1,174 (60%) mRNAs, the transcription start site was found exactly at (916 cases, 47%) or very close to the translation initiation codon AUG or GUG. Such proportion of leaderless mRNAs, which may resemble ancestral mRNAs, is unprecedented for a bacterial species. Proteomics showed that leaderless mRNAs are efficiently translated in D. deserti. Interestingly, we also found 173 additional transcripts with a 5?-AUG or 5?-GUG that would make them competent for ribosome binding and translation into novel small polypeptides. Fourteen of these are predicted to be leader peptides involved in transcription attenuation. Another 30 correlated with new gene predictions and/or showed conservation with annotated and nonannotated genes in other Deinococcus species, and five of these novel polypeptides were indeed detected by mass spectrometry. The data also allowed reannotation of the start codon position of 257 genes, including several DNA repair genes. Moreover, several novel highly radiation-induced genes were found, and their potential roles are discussed. On the basis of our RNA-seq and proteogenomics data, we propose that translation of many of the novel leaderless transcripts, which may have resulted from single-nucleotide changes and maintained by selective pressure, provides a new explanation for the generation of a cellular pool of small peptides important for protection of proteins against oxidation and thus for radiation/desiccation tolerance and adaptation to harsh environmental conditions. PMID:24723731

  10. Laser cooling of dense atomic gases by collisional redistribution of radiation and spectroscopy of molecular dimers in a dense buffer gas environment

    E-print Network

    Saß, Anne; Christopoulos, Stavros; Knicker, Katharina; Moroshkin, Peter; Weitz, Martin

    2014-01-01

    We study laser cooling of atomic gases by collisional redistribution of fluorescence. In a high pressure buffer gas regime, frequent collisions perturb the energy levels of alkali atoms, which allows for the absorption of a far red detuned irradiated laser beam. Subsequent spontaneous decay occurs close to the unperturbed resonance frequency, leading to a cooling of the dense gas mixture by redistribution of fluorescence. Thermal deflection spectroscopy indicates large relative temperature changes down to and even below room temperature starting from an initial cell temperature near 700 K. We are currently performing a detailed analysis of the temperature distribution in the cell. As we expect this cooling technique to work also for molecular-noble gas mixtures, we also present initial spectroscopic experiments on alkali-dimers in a dense buffer gas surrounding.

  11. Calculation of infrared spectral transmittances of inhomogeneous gases

    NASA Technical Reports Server (NTRS)

    Huffaker, R. M.

    1966-01-01

    Calculation of spectral transmittance for a particular inhomogeneous gas path is made by combining known data on gases at constant temperature, pressure, and concentration. The spectral transmittances of the inhomogeneous plume gases is needed to calculate the heat radiated from the exhaust plume to the rocket base of a multiple engine rocket.

  12. Noble gases in meteorites

    Microsoft Academic Search

    Donald D. Bogard

    1971-01-01

    The measurement of isotopic abundances of the noble gases in meteorites and other extraterrestrial samples became a large and active field during the past decade, especially within the last four years. The five stable noble gases proved to be excellent keys for unlocking the secrets of past physical events in the solar system and are used in studies of such

  13. Spectra and Latent Energy in Flame Gases

    Microsoft Academic Search

    Sydney Steele

    1935-01-01

    IN a recent letter on the above subject, Prof. W. T. David1 points out that after flame has travelled through an inflammable gaseous mixture, the gases remaining emit luminous (visible and ultra-violet) radiation for a considerable period of time if their temperature is kept up. In an investigation carried out at the United States Bureau of Standards, accounts of which

  14. 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.

  15. Measurements of Trace Gases Using a Tunable Diode Laser

    NASA Technical Reports Server (NTRS)

    Jost, Hans-Juerg

    2005-01-01

    This report is the final report for "Measurements of Trace Gases Using a Tunable Diode Laser." The tasks outlined in the proposal are listed below with a brief comment. The publications and the conference presentations are listed. Finally, the important publications are attached. The Cooperative Agreement made possible a research effort to produce high- precision and high-accuracy in-situ measurements of carbon monoxide, methane and nitrous oxide on the WB-57 during the CRYSTAL-FACE and pre-AVE field campaigns and to analyze these measurements. These measurements of CO and CH4 were of utmost importance to studies of the radiative effects of clouds. Some important results of the CRYSTAL-FACE program were contained in two scientific papers (attached). This Cooperative Agreement allowed the participation of the Argus instrument in the program and the analysis of the data.

  16. Abstract --Four-dimensional dynamic computed tomography (4D-dCT) plays an important role in radiation treatment

    E-print Network

    in radiation treatment planning, delivery, and verification for lung cancer management, in addition to heart-CT datasets are usually acquired in treatment planning for lung cancer [1]-[3]. Thus, the radiation dose of 4D in treatment planning for radiation therapy [1]-[3]. 4D-dCT contains information of tumor and normal organ

  17. Gases in Seawater

    NASA Astrophysics Data System (ADS)

    Nightingale, P. D.; Liss, P. S.

    2003-12-01

    The annual gross and net primary productivity of the surface oceans is similar in size to that on land (IPCC, 2001). Marine productivity drives the cycling of gases such as oxygen (O2), dimethyl sulfide (DMS), carbon monoxide (CO), carbon dioxide (CO2), and methyl iodide (CH3I) which are of fundamental importance in studies of marine productivity, biogeochemical cycles, atmospheric chemistry, climate, and human health, respectively. For example, ˜30% of the world's population (1,570 million) is thought to be at risk of iodine-deficiency disorders that impair mental development (WHO, 1996). The main source of iodine to land is the supply of volatile iodine compounds produced in the ocean and then transferred to the atmosphere via the air-surface interface. The flux of these marine iodine species to the atmosphere is also thought to be important in the oxidation capacity of the troposphere by the production of the iodine oxide radical ( Alicke et al., 1999). A further example is that the net flux of CO2 from the atmosphere to the ocean, ˜1.7±0.5 Gt C yr-1, represents ˜30% of the annual release of anthropogenic CO2 to the atmosphere (IPCC, 2001). This net flux is superimposed on a huge annual flux (90 Gt C yr-1) of CO2 that is cycled "naturally" between the ocean and the atmosphere. The long-term sink for anthropogenic CO2 is recognized as transfer to the ocean from the atmosphere. A final example is the emission of volatile sulfur, in the form of DMS, from the oceans. Not only is an oceanic flux from the oceans needed to balance the loss of sulfur (a bioessential element) from the land via weathering, it has also been proposed as having a major control on climate due to the formation of cloud condensation nuclei (Charlson et al., 1987). Indeed, the existence of DMS and CH3I has been used as evidence in support of the Gaia hypothesis (Lovelock, 1979).There are at least four main processes that affect the concentration of gases in the water column: biological production and consumption, photochemistry, air-sea exchange, and vertical mixing. We will not discuss the effect of vertical mixing on gases in seawater and instead refer the reader to Chapter 6.08. Nor will we consider the deeper oceans as this region is discussed in chapters on benthic fluxes and early diagenesis (Chapter 6.11), the biological pump (Chapter 6.04), and the oceanic calcium carbonate cycle (Chapter 6.19) all in this volume. We will discuss the cycling of gases in surface oceans, including the thermocline, and in particular concentrate on the exchange of various volatile compounds across the air-sea interface.As we will show, while much is known about the cycling of gases such as CO2 and DMS in the water column, frustratingly little is known about many of the chemical species for which the ocean is believed to be a significant source to the atmosphere. We suspect the passage of time will reveal that the cycling of volatile compounds containing selenium and iodine may well prove as complex as that of DMS. Early studies of DMS assumed that it was produced from a precursor compound, dimethylsulfoniopropionate (DMSP), known to be present in some species of phytoplankton, and that the main sink in the water column was exchange across the air-sea interface. We now know that DMSP and DMS are both rapidly cycled in water column by a complex interaction between phytoplankton, microzooplankton, bacteria, and viruses (see Figure 1). Some detailed process experiments have revealed that only ˜10% of the total DMS produced (and less than 1.3% of the DMSP produced) is transferred to the atmosphere, with the bulk of the DMS and DMSP, either being recycled in the water column or photo-oxidized (Archer et al., 2002b).

  18. Laboratory technique for the measurement of thermal-emission spectra of greenhouse gases: CFC-12

    NASA Astrophysics Data System (ADS)

    Evans, W. F. J.; Puckrin, E.

    1996-03-01

    A new technique has been developed to make possible the laboratory study of the infrared-emission spectra of gases of atmospheric interest. The thermal-emission spectra are in local thermodynamic equilibrium, just as they are in the atmosphere, and are not chemiluminescent. Demonstration results obtained by the use of this new technique are presented for dichlorodifluoromethane (CFC-12) at a pressure of 0.5 Torr in a cell with a path length of 5 cm. The measured cell spectra have been compared with simulations with the fascd3p radiation code. The measurements of the emission spectra of radiatively active gases may be important for the atmospheric greenhouse effect and global warming.

  19. Signatures of Annual and Seasonal Variations of CO2 and Other Greenhouse Gases from Comparisons between NOAA TOVS Observations and Radiation Model Simulations

    Microsoft Academic Search

    Alain Chédin; Soumia Serrar; Raymond Armante; Noëlle A. Scott; Anthony Hollingsworth

    2002-01-01

    Since 1979, sensors on board the National Oceanic and Atmospheric Administration (NOAA) series of polar meteorological satellites have provided continuous measurements of the earth's surface and atmosphere. One of these sensors, the Television Infrared Observational Satellite (TIROS-N) Operational Vertical Sounder (TOVS), observes earth-emitted radiation in the infrared-with the High-Resolution Infrared Sounder (HIRS)-and in the microwave-with the Microwave Sounding Unit (MSU)-portions

  20. 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.

  1. Photochemistry of biogenic gases

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.

    1989-01-01

    The relationship between the biosphere and the atmosphere is examined, emphasizing the composition and photochemistry and chemistry of the troposphere and stratosphere. The reactions of oxygen, ozone, and hydroxyl are reviewed and the fate of the biogenic gases ammonia, methane, reduced sulfur species, reduced halogen species, carbon monoxide, nitric oxide, nitrous oxide, nitrogen, and carbon dioxide are described. A list is given of the concentration and sources of the various gases.

  2. High-temperature properties of gases

    NASA Technical Reports Server (NTRS)

    Cooper, David M.

    1991-01-01

    Computational chemistry is being applied at NASA Ames Research Center to a variety of problems in chemistry, physics, and materials sciences. Supercomputers and modern computational chemistry techniques have provided a powerful new tool to help fill NASA's continuing need for information about the properties of gases and materials as well as their interaction. For example, radiative transition probabilities, spectroscopic constants, bond dissociation energies, transport properties, and chemical reaction rates for molecules can be determined computationally just as reliably as by experiment. Recent results on the radiative transition probabilities of the strongly radiating systems of air species, based on state-of-the-art computational chemistry calculations, are presented and compared with experimental data.

  3. 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

  4. 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.

  5. Self-action of a high-power 10-{mu}m laser radiation in gases: control of the pulse duration and generation of hot electrons

    SciTech Connect

    Gordienko, Vyacheslav M; Platonenko, Viktor T [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation); Sterzhantov, A F [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2009-07-31

    The propagation of ultrashort 10-{mu}m laser pulses of power exceeding the critical self-focusing power in xenon and air is numerically simulated. It is shown that the pulse duration in certain regimes in xenon can be decreased by 3-4 times simultaneously with the increase in the pulse power by 2-3 times. It is found that the average energy of electrons in a filament upon filamentation of 10-{mu}m laser pulses in air can exceed 200 eV. The features of the third harmonic and terahertz radiation generation upon filamentation are discussed. (special issue devoted to the 80th birthday of S.A. Akhmanov)

  6. Process gases for laser welding

    NASA Astrophysics Data System (ADS)

    Faerber, Mark; Berkmann, Joachim

    1997-08-01

    To achieve a high return on investment, laser systems must be used to their fullest capacity, avoiding power losses and downtimes. High-quality laser gases are therefore needed to run the laser. But if the quality of the gas cannot be guaranteed all the way from the cylinder to the laser cavity, the risk of impurities such as water vapor and hydrocarbons or particles entering the laser system is large. Unstable laser operation and damage to the resonator optics can result in costly repairs. The profitability of laser operations is also affected by the selection of the assist gas. High-purity oxygen and high-pressure high-purity nitrogen are frequently used to optimize the productivity of laser cutting. In contrast, different assist gases are used for laser welding depending on the wavelength of the laser radiation, the material, the energy per unit length of weld or the assist gas nozzle arrangement. Helium is often the most convenient choice for CO2 laser welding of mild steel, resulting in optimum seam quality with respect to formability and appearance. Helium-argon mixtures can be used effectively for lower power CO2 laser welding and for aluminum. Nitrogen mixtures may be used to stabilize the austenitic phase in duplex steels whereas hydrogen additions give a shiny bead surface in stainless steel. Argon is suitable for Nd:YAG laser welding and productivity is increased by small additions of oxygen. In addition argon- CO2 mixtures may be used to achieve acceptable results depending on the assist gas nozzle arrangement. Consequently, high-purity gases and suitable gas distribution equipment are the basis for a satisfactory return on investment.

  7. Detailed discussion of a linear electric field frequency shift (important for next generation) electric dipole moment searches) induced in confined gases by a magnetic field gradient: Implications for electric dipole moment experiments (II)

    E-print Network

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

    2005-12-20

    The search for particle electric dipole moments 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 E x v field with magnetic field gradients (often referred to as the geometric phase effect [9,10]). This interaction produces a frequency shift linear in the electric field, mimicking an edm. In this work we introduce an analytic model for the correlation function which determines the behavior of the frequency shift [11], and show in detail how it depends on the operating conditions of the experiment. We also propose a method to directly measure ths correlation function under the exact conditions of a given experiment.

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

    PubMed

    Tomita, Masanori; Maeda, Munetoshi

    2015-03-01

    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

  9. Gases: Characteristics and Properties

    NSDL National Science Digital Library

    Brieske, Joel A.

    The first site related to ideal gas, called Ideal and Real Gas Laws, is maintained by Liina Ladon of Townsen University (1). Visitors can read about the properties of ideal gases, what the ideal gas law is, how to use it, and much more. The next site, titled Gas Laws, (2) is offered by the Ohio State University Department of Chemistry. This interactive site contains Shockwave movies of animations and audio files that describe what a gas is, the Ideal Gas Law equation, mixtures of gases, and problems using the ideal gas law. The University of Oregon site, Virtual Laboratory, teaches about the ideal gas law on the Welcome to the Pressure Chamber page (3). Those who enjoy online interaction will enjoy being able to control the action of a piston in a pressure chamber to see how the gases inside react. The fourth site includes another fun multimedia activity related to ideal gases provided by the Department of Physics and Astronomy at Western Washington University. The Air Filled Balloon in Liquid Nitrogen (4) movie shows an actual experiment of the effects on a balloon that's covered with liquid nitrogen. The page contains some additional information on the science behind the observations. The next site, called Ideal Gas Equations (5) is an online calculator that's part of Kean University's Department of Geology and Meteorology Web site. Users can calculate the pressure, volume, or temperature of a gas by inputting known variables into the various forms. Several methods and variations of calculating the values are provided as well as brief instructions. The next page from North Carolina State University's Basic Concepts in Environmental Science Web site is called Characteristics of Gases (6). Part of a larger learning module, the lesson plans objective is to use the ideal gas law to determine gas volumes at different absolute temperatures and absolute pressures. Everything needed to conduct the activity is provided including links to a volume calculator and practice problems. The seventh site is another animation that illustrates how gases react, called Molecular Model for an Ideal Gas (7). By changing the number of molecules in the chamber, their velocity, and the pressure and width of the container, users get to see how the molecules react to the conditions. The last site, Gases and Their Properties, is maintained by the Electronic Teaching Assistance Program(8). Students learn about the history of gas science, how gas laws describe ideal gases, what Dalton's Law and Graham's Law are, and much more.

  10. 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.

  11. Biogeophysical effects of land use on climate: Model simulations of radiative forcing and large-scale temperature change

    Microsoft Academic Search

    Richard A. Betts; Peter D. Falloon; Kees Klein Goldewijk; Navin Ramankutty

    2007-01-01

    Changes in land cover affect climate through the surface energy and moisture budgets. Here we assess the importance of these biogeophysical effects for present-day climate, and quantify the radiative forcing of historical climate change by land use change for comparison with radiative forcings due to anthropogenic changes in greenhouse gases and aerosols. We also discuss the implications of biogeophysical effects

  12. 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.

  13. Investigation of Ultrafast Laser-Driven Radiative Blast Waves

    Microsoft Academic Search

    M. J. Edwards; A. J. MacKinnon; J. Zweiback; K. Shigemori; D. Ryutov; A. M. Rubenchik; K. A. Keilty; E. Liang; B. A. Remington; T. Ditmire

    2001-01-01

    We have examined the evolution of cylindrically symmetric blast waves produced by the deposition of femtosecond laser pulses in gas jets. In high- Z gases radiative effects become important. We observe the production of an ionization precursor ahead of the shock front and deceleration parameters below the adiabatic value of 1\\/2 (for a cylinder), an effect expected when the blast

  14. 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,...

  15. Eco gases for future particle gas detectors

    E-print Network

    Kjølbro, Jógvan Nikolaj

    2014-01-01

    Due to global regulations of non environmental refrigerants, some of the gas mixtures used in gas detectors at CERN has to be replaced. This report is a review that summarises and predicts some properties that are important when selecting new gases to operate in the gas detectors.

  16. DOSIMETRY MODELING OF INHALED TOXIC REACTIVE GASES

    EPA Science Inventory

    The report focuses on the physical, chemical and biological processes and factors involved in the absorption of reactive gases. Emphasis is placed on the importance of these factors in developing dosimetry models, special consideration being given to the role of lung fluids and t...

  17. 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...

  18. 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.

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

    SciTech Connect

    Edmonds, J.A.; Chandler, W.U. (Pacific Northwest Lab., Richland, WA (USA)); Wuebbles, D. (Lawrence Livermore National Lab., CA (USA))

    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.

  20. Vibrational Relaxation in Gases

    Microsoft Academic Search

    J. D. Lambert; R. Salter

    1959-01-01

    The velocity of ultrasonic waves has been measured in a number of gases at 25 degrees C and for values of the ratio, ultrasonic frequency\\/pressure, ranging from 2 × 105 to 2 × 107 c s-1 atm-1. Dispersion, corresponding to a single vibrational relaxation process was shown by acetylene, CD3Br and hexafluoro-ethane; and, to a double relaxation process, by ethane.

  1. 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. [School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ (United Kingdom); Proga, Daniel [Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, NV 89154-4002 (United States); Long, Knox S. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Sim, Stuart A., E-mail: nick_higginbottom@fastmail.fm [School of Mathematics and Physics, Queens University Belfast, University Road, Belfast, BT7 1NN (United Kingdom)

    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.

  2. [Computerized tomography of the female thorax after mastectomy: the most important topometric data from the viewpoint of radiation].

    PubMed

    Baumgartner, E

    1991-01-01

    The author analysed postoperative CT images of 77 patients operated on carcinoma of the breast and performed topometric measurements on the level of sternoclavicular joints parasternal, and in the centre line of the sternum in the height of the second and sixth intercostal space as well as on the thorax wall medioclavicular and on the forepart of the axillar line. The values measured corresponded to the literary data in general except those of the second intercostal space and of the axilla. The author stresses the necessity of CT series when making radiation planning of breast cancer. PMID:1992538

  3. Relative importance of acid coating on ice nuclei in the deposition and contact modes for wintertime Arctic clouds and radiation

    NASA Astrophysics Data System (ADS)

    Girard, Eric; Sokhandan Asl, Niloofar

    2014-01-01

    Aerosols emitted from volcanic activities and polluted mid-latitudes regions are efficiently transported over the Arctic during winter by the large-scale atmospheric circulation. These aerosols are highly acidic. The acid coating on ice nuclei, which are present among these aerosols, alters their ability to nucleate ice crystals. In this research, the effect of acid coating on deposition and contact ice nuclei on the Arctic cloud and radiation is evaluated for January 2007 using a regional climate model. Results show that the suppression of contact freezing by acid coating on ice nuclei leads to small changes of the cloud microstructure and has no significant effect on the cloud radiative forcing (CRF) at the top of the atmosphere when compared with the effect of the alteration of deposition ice nucleation by acid coating on deposition ice nuclei. There is a negative feedback by which the suppression of contact freezing leads to an increase of the ice crystal nucleation rate by deposition ice nucleation. As a result, the suppression of contact freezing leads to an increase of the cloud ice crystal concentration. Changes in the cloud liquid and ice water contents remain small and the CRF is not significantly modified. The alteration of deposition ice nucleation by acid coating on ice nuclei is dominant over the alteration of contact freezing.

  4. Chemical reactions of mercury in combustion flue gases

    Microsoft Academic Search

    B. Hall; P. Schager; O. Lindqvist

    1991-01-01

    Atmospheric Hg is present in different physical and chemical forms, which determine its atmospheric transformation and transport\\u000a capacities. The chemistry of Hg in flue gases is thus of importance for the deposition pattern around point source emissions.\\u000a In order to apply Hg cleaning methods in flue gases its speciation is also of importance. To investigate this under realistic\\u000a conditions, a

  5. NMR studies and applications of perfluorocarbon gases

    NASA Astrophysics Data System (ADS)

    Chang, Yulin

    Hyperpolarized 3He has been very successful in magnetic resonance imaging (MRI) of the lungs. It provides ways to study the physiological properties of the lungs and lung function. However, the high costs of the polarizing apparatus and the complicated polarizing procedure are preventing this technique from being clinically used routinely. Recent developments have shown that several fluorinated gases have the potential to replace 3He in some of its applications. This thesis presents some preliminary results of human excised lung imaging using C2F6 and C3F8. These two fluorinated gases were able to yield images with good signal-to-noise ratio and reasonable resolutions in a 1.5 T magnet. Using diffusion MRI of these two gases can distinguish emphysematous lungs from healthy ones. An important application of these gases would be to determine local lung surface-to-volume (S/V) ratio in vivo, which requires the unrestricted (free) diffusivity in each pixel to be known. We present data in this thesis which allow free diffusivities to be calculated from the relaxation time T1. Samples of pure C 2F6 and C3F8 at different pressures and in mixtures with oxygen at different concentrations were made. Measurements were done at two different magnetic fields and temperature was regulated to study the temperature dependence over a small range. These two gases were also used in studies of carbon-block filters, where the strong adsorption of the gases to the high surface-area carbon is beneficial. A brief review of our work on mouse lung imaging using hyperpolarized 3He is presented in Appendix A; Appendix B is a study of the longitudinal spin magnetization in the presence of a strong magnetic field gradient; the construction of the pulsed field gradient waveform measurement coils and some experimental results using these coils are contained in Appendix C.

  6. The temporal and spatial variability of halogenated trace gases in the upper troposphere.

    NASA Astrophysics Data System (ADS)

    Oram, D.; O'Sullivan, D.; Brenninkmeijer, C.; van Velthoven, P.; Sturges, W.

    2007-12-01

    Halogenated trace gases play an important role in stratospheric and tropospheric chemistry, particularly affecting ozone concentrations. In addition they have direct and indirect effects on radiative forcing, and impact on tropospheric reactivity. Data from the CARIBIC project (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrumented Container) have been used in conjunction with back-trajectory analysis to further our understanding of the chemical composition, inter-hemispheric distribution and source regions of halogenated compounds in the upper troposphere and lower stratosphere. Whole air samples collected within CARIBIC, have been analyzed using gas chromatography mass spectrometry for around 35 halocarbons and related trace gases, among them many potent greenhouse gases and species important for ozone depletion. The large spatial and temporal coverage of the CARIBIC project has enabled new work to be done investigating recent inter-annual trends in the CFCs, halons, and other anthropogenic halocarbons, as well as identifying clear inter-hemispheric and seasonal variability for a number of species, such as methylene chloride, HCFCs, methyl chloride, methyl bromide, methyl iodide and several reactive short lived bromo and chloro carbons. In this paper results from the CARIBIC flights to China and the Philippines will be highlighted, to discuss anthropogenic emissions of ozone depleting and greenhouse gases, from Asia and Africa. Data from flights to South America will also be presented. As production and consumption of many of these substances are being phased out in Europe and North America, emissions from Asia, Africa and also South America are becoming increasingly more important. Emissions from these regions are also of interest, as the most significant sources are often collocated with regions of convection in the tropics and sub-tropics. Thus enabling a greater proportion of the substances emitted to reach the stratosphere, where they have the largest impact on ozone.

  7. Radiators

    Microsoft Academic Search

    1985-01-01

    A heat-exchange radiator is connected to a fluid flow circuit by a connector which provides one member of an interengageable spigot and socket pair for push-fit, fluid-tight, engagement between the connector and the radiator, with latching formations at least one of which is resilient. Preferably the connector carries the spigot which tapers and engages with a socket of corresponding shape,

  8. Radiation 

    E-print Network

    Unknown

    2011-08-17

    State. s. ABSTRACT This study is an attempt to find a tentative atmospheric index of human comfort and to show its applications for the area of College Station~ Texas. Temperature, relative humidity~ air move- ment, and global short-wave radiation... (direct plus diffuse) were combined into a single numerical expression for outdoor human comfort. The contribution of global short-wave radiation to the heat load on man also is evaluated in a single numerical expression, and expressed as an equivalent...

  9. Viscosity model for pure gases at atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Miadonye, Adango; McKenna, Tara M.

    2005-06-01

    The production processes for petroleum gases use a broad range of simulation packages to reduce the capital, time, and cost associated with actual recovery and pipeline transportation. The viscosity model is an important component of these packages. In this study, two simple-to-use empirical models are presented for predicting the viscosity of petroleum gases: the three-parameter Yaws equation; and the correlation of Miadonye-Clyburn. New values were obtained for the constants in Yaws’ equation for various hydrocarbon gases. Alternatively, the Yaws equation has been extended to cover nonhydrocarbon gases, some for the first time, and new values were derived for the constants for these gases. The results obtained with the new constants were compared with the viscosity predictions from both the Yaws and the Miadonye-Clyburn correlations. For four petroleum gases and two nonhydrocarbon gases at temperatures from 100 to 1500 K, the models gave viscosity predictions with overall average absolute deviations of 0.30 and 0.75% for the Yaws correlation with new constants, and 1.17 and 2.7% for the Miadonye-Clyburn correlation for viscosity predictions based on one viscosity value. Both models are simple to incorporate in design and simulation packages, and are accurate within the limits of experimental errors for the viscosities of petroleum gases.

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

    SciTech Connect

    McBride, Sean M.; Daganzo, Sally M. [Department of Radiation Oncology, University of California-San Francisco, San Francisco, CA (United States); Banerjee, Anuradha [Department of Pediatrics, University of California-San Francisco, San Francisco, CA (United States); Gupta, Nalin; Lamborn, Kathleen R.; Prados, Michael D.; Berger, Mitchel S. [Department of Neurological Surgery and Brain Tumor Research Center, University of California-San Francisco, San Francisco, CA (United States); Wara, William M. [Department of Radiation Oncology, University of California-San Francisco, San Francisco, CA (United States); Haas-Kogan, Daphne A. [Department of Radiation Oncology, University of California-San Francisco, San Francisco, CA (United States); Department of Neurological Surgery and Brain Tumor Research Center, University of California-San Francisco, San Francisco, CA (United States)], E-mail: dhaaskogan@radonc.ucsf.edu

    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.

  11. Residual Gases in Crystal Growth Systems

    NASA Technical Reports Server (NTRS)

    Palosz, W.

    2003-01-01

    Residual gases present in closed ampoules may affect different crystal growth processes. That seems to be particularly true under microgravity conditions where, due to weightlessness of the melt, the gases may lead to detached solidification and/or formation of voids and bubbles, as observed in the past. For that reason a good understanding and control of formation of residual gases is important for an optimum design and meaningful interpretation of crystal growth experiments. Our extensive experimental and theoretical studies of the subject, summarized in this paper, include degassing of silica glass and generation of gases from different 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.

  12. 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.

  13. Radiation dosimetry.

    PubMed Central

    Cameron, J

    1991-01-01

    This article summarizes the basic facts about the measurement of ionizing radiation, usually referred to as radiation dosimetry. The article defines the common radiation quantities and units; gives typical levels of natural radiation and medical exposures; and describes the most important biological effects of radiation and the methods used to measure radiation. Finally, a proposal is made for a new radiation risk unit to make radiation risks more understandable to nonspecialists. PMID:2040250

  14. Differentiation of the radiation-induced necrosis and tumor recurrence after gamma knife radiosurgery for brain metastases: importance of multi-voxel proton MRS.

    PubMed

    Chernov, M; Hayashi, M; Izawa, M; Ochiai, T; Usukura, M; Abe, K; Ono, Y; Muragaki, Y; Kubo, O; Hori, T; Takakura, K

    2005-08-01

    Comparative analysis of the diagnostic accuracy of FDG PET, single-voxel, and multi-voxel proton MRS for differentiation between radiation-induced necrosis and tumor recurrence was done in 9 patients with brain metastases treated by gamma knife radiosurgery. In all cases enlargement of the lesion and increase of the perilesional edema were demonstrated by MRI on average 10.6+/-2.6 months after initial treatment. Radiation-induced necrosis was identified in 5 patients (histologically in 2, clinically in 3). In one of these a false positive result of FDG PET was observed, whereas data of proton MRS were always correct. The diagnosis of tumor recurrence was established in 4 patients (histologically in 3, clinically in 1). Among these both FDG PET and single-voxel proton MRS showed false negative results (each method twice), whereas multi-voxel proton MRS always permitted us to establish the correct diagnosis. The present study demonstrates the higher diagnostic accuracy of multi-voxel proton MRS, in comparison with single-voxel proton MRS and FDG PET, for the differentiation of the radiation-induced necrosis and tumor recurrence. Its use is especially important in mixed lesions with co-existence of both post-irradiation changes and viable neoplasm. Monitoring of the treatment response by serial multi-voxel proton MRS seems to be reasonable during follow-up of patients with brain metastases after radiosurgery. PMID:16172969

  15. Diffusivity of Lattice Gases

    NASA Astrophysics Data System (ADS)

    Quastel, Jeremy; Valkó, Benedek

    2013-10-01

    We consider one-component lattice gases with local dynamics and a stationary product Bernoulli measure on {{Z}^d}. We study the scaling exponents of the space-time correlations of the system in equilibrium at a given density. We consider a variance-like quantity computed from the correlations called the diffusivity (connected to the Green-Kubo formula) and give rigorous upper and lower bounds on it that depend on the dimension and the local behavior of the macroscopic flux function. Our results identify the cases in which the system scales superdiffusively; these cases have been predicted before, using non-rigorous scaling arguments. Our main tool is the resolvent method: the estimates are the result of a careful analysis of a complicated variational problem.

  16. 8, 82738326, 2008 Greenhouse gases

    E-print Network

    Boyer, Edmond

    ACPD 8, 8273­8326, 2008 Greenhouse gases from satellite ­ Part 2: Methane O. Schneising et al.0 License. Atmospheric Chemistry and Physics Discussions Three years of greenhouse gas column-averaged dry­8326, 2008 Greenhouse gases from satellite ­ Part 2: Methane O. Schneising et al. Title Page Abstract

  17. 8, 54775536, 2008 Greenhouse gases

    E-print Network

    Boyer, Edmond

    ACPD 8, 5477­5536, 2008 Greenhouse gases from satellite ­ Part 1: CO2 O. Schneising et al. Title.0 License. Atmospheric Chemistry and Physics Discussions Three years of greenhouse gas column-averaged dry­5536, 2008 Greenhouse gases from satellite ­ Part 1: CO2 O. Schneising et al. Title Page Abstract

  18. 5, 213242, 2008 Greenhouse gases

    E-print Network

    Paris-Sud XI, Université de

    BGD 5, 213­242, 2008 Greenhouse gases German bog S. Glatzel et al. Title Page Abstract Introduction Discussions is the access reviewed discussion forum of Biogeosciences Environmental controls of greenhouse gas Correspondence to: S. Glatzel (stephan.glatzel@uni-rostock.de) 213 #12;BGD 5, 213­242, 2008 Greenhouse gases

  19. Voluntary Reporting of Greenhouse Gases

    EIA Publications

    2011-01-01

    The Voluntary Reporting of Greenhouse Gases Program was suspended May 2011. It was a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., could report to the Energy Information Administration, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

  20. Kinetic Molecular Theory of Gases

    NSDL National Science Digital Library

    David N. Blauch

    Applets dealing with the meaning of the Maxwell distribution of gases and pressure of gases are discussed. The Maxwell distribution experiment allow the user to explore the most probable speed of gas molecules. The pressure experiment allows the user to explore the effects of size and mass on collision rate, direction, and relative speed of gas molecules within a fixed volume.

  1. Greenhouse effect of chlorofluorocarbons and other trace gases

    Microsoft Academic Search

    James Hansen; Andrew Lacis; Michael Prather

    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

  2. Impact of carbon dioxide, trace gases, and climate change on global agriculture

    SciTech Connect

    Not Available

    1990-01-01

    Global climate change is one of several important issues that will command the attention of policymakers and scientist in the 1990s. The evidence that concentrations of carbon dioxide (CO{sub 2}), and other gases are increasing in the atmosphere is irrefutable. The evidence, and the knowledge that CO{sub 2} and trace gases may absorb thermal radiation sufficient to warm the atmosphere, has prompted much speculation that ensuing atmospheric warming may lead to changes in the distribution of precipitation, and of crop adaptation and productivity, that would alter the world supply of food and fiber. The implications of this speculation are compelling for agronomists, because agronomists are stewards of the world's food supply and of the natural resources that are used to produce food. Agronomists have a pivotal role in conducting the research needed to anticipate crop response to climate changes, and in informing policymakers and the general public about the adequacy of our knowledge. In this publication agronomists assess the current status of scientific knowledge about the putative role of greenhouse gases in global climate change and report their findings.

  3. The importance of energetic particle injections and cross-energy and -species interactions to the acceleration and loss of relativistic electrons in Earth's outer radiation belt (invited talk)

    NASA Astrophysics Data System (ADS)

    Turner, Drew; Gkioulidou, Matina; Ukhorskiy, Aleksandr; Gabrielse, Christine; Runov, Andrei; Angelopoulos, Vassilis

    2014-05-01

    Earth's radiation belts provide a natural laboratory to study a variety of physical mechanisms important for understanding the nature of energetic particles throughout the Universe. The outer electron belt is a particularly variable population, with drastic changes in relativistic electron intensities occurring on a variety of timescales ranging from seconds to decades. Outer belt variability ultimately results from the complex interplay between different source, loss, and transport processes, and all of these processes are related to the dynamics of the inner magnetosphere. Currently, an unprecedented number of spacecraft are providing in situ observations of the inner magnetospheric environment, including missions such as NASA's THEMIS and Van Allen Probes and ESA's Cluster and operational monitors such as NOAA's GOES and POES constellations. From a sampling of case studies using multi-point observations, we present examples showcasing the significant importance of two processes to outer belt dynamics: energetic particle injections and wave-particle interactions. Energetic particle injections are transient events that tie the inner magnetosphere to the near-Earth magnetotail; they involve the rapid inward transport of plasmasheet particles into the trapping zone in the inner magnetosphere. We briefly review key concepts and present new evidence from Van Allen Probes, GOES, and THEMIS of how these injections provide: 1. the seed population of electrons that are subsequently accelerated locally to relativistic energies in the outer belt and 2. the source populations of ions and electrons that produce a variety of ULF and VLF waves, which are also important for driving outer belt dynamics via wave-particle interactions. Cases of electron acceleration by chorus waves, losses by plasmaspheric hiss and EMIC waves, and radial transport driven by ULF waves will also be presented. Finally, we discuss the implications of this developing picture of the system, namely how variations in the flux of relativistic electrons in Earth's outer radiation belt are intricately tied to particle injections from the magnetotail, electrons and ions in the ring current, and the wave environment throughout the inner magnetosphere.

  4. 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.

  5. Radiation

    Microsoft Academic Search

    Erik Seedhouse

    \\u000a It is more than forty years since astronauts ventured beyond Earth’s protective magnetic shield and travelled to the Moon.\\u000a Although the Apollo missions subjected astronauts to space radiation, the short duration minimized the risk, but an ECM will\\u000a subject astronauts to much longer exposure. In fact, astronauts will be in deep space for so long, they will run the risk

  6. Thermal conductivity in vibrationally excited gases.

    NASA Technical Reports Server (NTRS)

    Ahtye, W. F.

    1972-01-01

    Comparisons between experimental and theoretical values of the thermal conductivity for a series of nonpolar polyatomic gases show large discrepancies at higher temperatures where the vibrational contribution becomes increasingly important. Examination of various theoretical approaches indicates that the discrepancies can be attributed to approximating the coefficient characterizing the diffusion of vibrational energy, D sub vib, by the self-diffusion coefficient. The present theories cannot accurately predict D sub vib, and its measurement is extremely difficult. Consequently, the approach adopted by the author is to obtain D sub vib by using experimental values of the thermal conductivity. An attempt is made to correlate these values of D sub vib with vibrational relaxation time, so that values of D sub vib can be obtained for all nonpolar polyatomic gases.

  7. Discharges In Electronegative Gases

    NASA Astrophysics Data System (ADS)

    Franklin, R. N.

    2008-10-01

    This talk will come in three parts. First, the early work in electronegative plasmas, principally by Emeleus and co-workers in Iodine, and by Massey and co-workers in Oxygen. They were at opposite ends of the ``spectrum'' of electronegativity - the ratio of negative ion density to electron density. Secondly, we cover in more detail work in Oxygen, where in retrospect we know that too many parameters were included to reveal the underlying structure of electronegative plasmas. That is associated with Edgley and von Engel, and later with Ferriera and co-workers. From there until the present day we describe work coming from different directions, showing that by questioning prior assumptions, we have arrived at our present understanding. The basic elements are, that in general there is a negative ion core, surrounded by a conventional plasma, and that at low pressures the situation is significantly different from higher pressures. The talk will seek to avoid mathematical complexity and concentrate on the physics, explaining the reason for previous differences, and show the way forward for a more Complete understanding of the very complex problem of strongly electronegative plasmas and their structure when diluted by rare gases. All of this involves a multiplicity of ion species of both signs, and a variety of reaction rates.

  8. Investigating and Using Biomass Gases

    NSDL National Science Digital Library

    Eric Benson

    2012-07-03

    In this activity, learners will be introduced to biomass gasification and will generate their own biomass gases. Learners generate these gases everyday on their own and find it quite amusing, but this time they’ll do it by heating wood pellets or wood splints in a test tube. They will collect the resulting gases and use the gas to roast a marshmallow. Learners will also evaluate which biomass fuel is the best either according to their own criteria or by examining the volume of gas produced by each type of fuel.

  9. Noble gases in the moon

    NASA Technical Reports Server (NTRS)

    Manuel, O. K.; Srinivasan, B.; Hennecke, E. W.; Sinclair, D. E.

    1972-01-01

    The abundance and isotopic composition of helium, neon, argon, krypton, and xenon which were released by stepwise heating of lunar fines (15601.64) and (15271.65) were measured spectrometrically. The results of a composition of noble gases released from the lunar fines with noble gases in meteorites and in the earth are presented along with the isotopic composition of noble gases in lunar fines, in meteorites, and in the atmosphere. A study of two isotopically distinct components of trapped xenon in carbonaceous chondrites is also included.

  10. Process of selectively desulfurizing gases

    SciTech Connect

    Doerges, A.; Kempf, G.; Schlauer, J.

    1981-10-27

    In a process of selectively desulfurizing gases which contain hydrogen sulfide and carbon dioxide comprising scrubbing the gases with an aqueous potassium carbonate solution under superatmospheric pressure and at temperatures of about 100* C., regenerating the laden scrubbing solution and recycling the regenerated scrubbing solution, the improvement wherein the gases to be purified are scrubbed with an aqueous potassium carbonate solution so as to maintain a mass ratio of 1.0 to 3.0 vals (Gram equivalents) of alkali in the solution per mole of co2 and h2s in the gases to be purified, the laden scrubbing liquor is subsequently regenerated by being stripped with a gas in which a co2 partial pressure above 0.2 bar is maintained, and the so regenerated scrubbing solution is recycled.

  11. Process of selectively desulfurizing gases

    SciTech Connect

    Schlauer, J.; Kempf, G.; Doerges, A.

    1981-10-27

    This process selectively desulfurizes gases which contain hydrogen sulfide and carbon dioxide. It is comprised of scrubbing the gases with an aqueous potassium carbonate solution under superatmospheric pressure and at temperatures of ca. 100 c. The laden scrubbing solution is regenerated and the regenerated scrubbing solution is recycled. In turn, the gases to be purified are scrubbed with an aqueous potassium carbonate solution so as to maintain a mass ratio of 1.0 to 3.0 vals (gram equivalents) of alkali in the solution per mole of CO/sub 2/ and H/sub 2/S in the gases to be purified. The laden scrubbing liquor is subsequently regenerated by being stripped with a gas in which a CO/sub 2/ partial pressure above 0.2 bar is maintained, and the regenerated scrubbing solution is recycled. 7 claims.

  12. 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.

  13. 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.

  14. MRI using hyperpolarized noble gases

    Microsoft Academic Search

    H.-U. Kauczor; R. Surkau; T. Roberts

    1998-01-01

    .   The aim of this study was to review the physical basis of MRI using hyperpolarized noble gases as well as the present status\\u000a of preclinical and clinical applications. Non-radioactive noble gases with a nuclear spin 1\\/2 (He-3, Xe-129) can be hyperpolarized\\u000a by optical pumping. Polarization is transferred from circularly polarized laser light to the noble-gas atoms via alkali-metal\\u000a vapors

  15. Hydrodynamics of unitary Fermi gases

    NASA Astrophysics Data System (ADS)

    Young, Ryan E.

    Unitary fermi gases have been widely studied as they provide a tabletop archetype for re- search on strongly coupled many body systems and perfect fluids. Research into unitary fermi gases can provide insight into may other strongly interacting systems including high temperature superconductor, quark-gluon plasmas, and neutron stars. Within the unitary regime, the equilib- rium transport coefficients and thermodynamic properties are universal functions of density and temperature. Thus, unitary fermi gases provide a archetype to study nonperturbative many-body physics, which is of fundamental significance and crosses several fields. This thesis reports on two topics regarding unitary fermi gases. A recent string theory conjecture gives a lower bound for the dimensionless ratio of shear viscosity of entropy, ?/s ? 4pi /kb . Unitary fermi gases are a candidate for prefect fluids, yet ?/s is well above the string theory bound. Using a stochastic formulation of hydrodynamics, we calculate a lower bound for this ratio accounting for the momentum dissipation from fluctuations. This lower bound is in good agreement with both theoretical and experimental results. The second question addressed is the simulation of elliptic flow. Elliptic flow, first observed in 2002, is a characteristic of strongly coupled systems and has been studied in both quark-gluon plasmas and unitary fermi gases. As such, simulations of these systems are of interest. We test a variety of lattice Boltzmann models and compare the simulation results to the theoretical and experimental findings.

  16. Review of Electron Interaction Data for Plasma Processing Gases

    NASA Astrophysics Data System (ADS)

    Olthoff, James

    1998-10-01

    To assess the behavior of gases in their uses in manufacturing semiconductor devices and other applications, and to promote the modeling of these processes, it is necessary to have accurate information on the fundamental interactions of low energy (< 100 eV) electrons with process gases. In support of this effort, we have undertaken the assessment and evaluation of the available information on cross sections and rate coefficients for collisional interactions of electrons with three groups of gases: those used in etching, deposition, or cleaning (e.g., CF_4, CHF_3, C_2F_6, C_3F_8, Cl_2, SF_6, NF3 and HBr), those used as buffer gases (e.g., Ar, He), and those that are present in practical systems as impurities (e.g., O_2, N_2, H_2O). In this talk we summarize our assessed data on cross sections and rate coefficients for the gases whose review is completed: CF4 , CHF_3, C_2F6 , C_3F_8, and Cl_2. We also indicate specific electron-interaction data needs for these gases. In this regard, knowledge is lacking on two important basic processes, namely, dissociation into neutral fragments by electron impact and electron interactions with vibrationally and electronically excited species. In addition, with the sole exception of the electron-impact ionization of radicals from CF_4, there are few published data on the interactions of slow electrons with the radicals of these plasma processing gases. The recommended data for the reviewed gases and CCl_2F2 are available via the World Wide Web at http://www.eeel.nist.gov/811/refdata.

  17. 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.

  18. On flame kernel formation and propagation in premixed gases

    SciTech Connect

    Eisazadeh-Far, Kian; Metghalchi, Hameed [Northeastern University, Mechanical and Industrial Engineering Department, Boston, MA 02115 (United States); Parsinejad, Farzan [Chevron Oronite Company LLC, Richmond, CA 94801 (United States); Keck, James C. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2010-12-15

    Flame kernel formation and propagation in premixed gases have been studied experimentally and theoretically. The experiments have been carried out at constant pressure and temperature in a constant volume vessel located in a high speed shadowgraph system. The formation and propagation of the hot plasma kernel has been simulated for inert gas mixtures using a thermodynamic model. The effects of various parameters including the discharge energy, radiation losses, initial temperature and initial volume of the plasma have been studied in detail. The experiments have been extended to flame kernel formation and propagation of methane/air mixtures. The effect of energy terms including spark energy, chemical energy and energy losses on flame kernel formation and propagation have been investigated. The inputs for this model are the initial conditions of the mixture and experimental data for flame radii. It is concluded that these are the most important parameters effecting plasma kernel growth. The results of laminar burning speeds have been compared with previously published results and are in good agreement. (author)

  19. Abating environmentally harmful waste gases

    NASA Astrophysics Data System (ADS)

    Sridhar, S.; Sichen, Du; Pal, U. B.; Seetharaman, S.

    2002-05-01

    A gas-purification method, based on the condensation of nitrogen, sulfur, and carbon-containing environmentally hazardous gases produced from industrial processes, is proposed in this article. The method, which utilizes the cooling capacity of waste nitrogen in the oxygen plant to condense the hazardous gases, is capable of removing hazardous impurities up to 99.98%. Theoretical calculations underlying the condensation process are presented employing gases produced in a blast furnace and coke oven in an integrated steel plant. The cooling power required for the condensation process is calculated using the waste nitrogen generated from an oxygen plant that generates captive oxygen for the steel plant. Design modifications that need to be made to the oxygen plant in order to utilize the cooling power of the waste nitrogen gas are also presented. As a case study, the advantages of the method are illustrated with purification of coke-oven gas. The economic impact and the investment aspects are also discussed.

  20. Hot Topics in Cold Gases

    E-print Network

    Robert Seiringer

    2009-08-25

    Since the first experimental realization of Bose-Einstein condensation in cold atomic gases in 1995 there has been a surge of activity in this field. Ingenious experiments have allowed us to probe matter close to zero temperature and reveal some of the fascinating effects quantum mechanics has bestowed on nature. It is a challenge for mathematical physicists to understand these various phenomena from first principles, that is, starting from the underlying many-body Schr\\"odinger equation. Recent progress in this direction concerns mainly equilibrium properties of dilute, cold quantum gases. We shall explain some of the results in this article, and describe the mathematics involved in understanding these phenomena. Topics include the ground state energy and the free energy at positive temperature, the effect of interparticle interaction on the critical temperature for Bose-Einstein condensation, as well as the occurrence of superfluidity and quantized vortices in rapidly rotating gases.

  1. The Solar Cycle Transition and High Speed Streams as evidenced in SABER Infrared Radiative Cooling Observations in the Thermosphere

    Microsoft Academic Search

    L. A. Hunt; M. G. Mlynczak; B. T. Marshall; C. J. Mertens; J. Russell

    2010-01-01

    The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite has been making continuous measurements of the vertical distribution of infrared radiation emitted by various atmospheric gases (ozone, water vapor, O2(singlet delta), OH, nitric oxide, and carbon dioxide) since January 2002, providing important information about the radiation budget in the upper

  2. MRI using hyperpolarized noble gases.

    PubMed

    Kauczor, H; Surkau, R; Roberts, T

    1998-01-01

    The aim of this study was to review the physical basis of MRI using hyperpolarized noble gases as well as the present status of preclinical and clinical applications. Non-radioactive noble gases with a nuclear spin 1/2 (He-3, Xe-129) can be hyperpolarized by optical pumping. Polarization is transferred from circularly polarized laser light to the noble-gas atoms via alkali-metal vapors (spin exchange) or metastable atoms (metastability exchange). Hyperpolarization results in a non-equilibrium polarization five orders of magnitude higher than the Boltzmann equilibrium compensating for the several 1000 times lower density of noble gases as compared with liquid state hydrogen concentrations in tissue and allows for short imaging times. Hyperpolarization can be stored sufficiently long (3 h to 6 days) to allow for transport and application. Magnetic resonance systems require a broadband radio-frequency system - which is generally available for MR spectroscopy - and dedicated coils. The hyperpolarized gases are administered as inhalative "contrast agents" allowing for imaging of the airways and airspaces. Besides the known anesthetic effect of xenon, no adverse effects are observed in volunteers or patients. Pulse sequences are optimized to effectively use the non-renewable hyperpolarization before it decays or is destroyed, using fast low-flip-angles strategies to allow for dynamic/breath-hold imaging of highly diffusible (He) or soluble (Xe) gases with in vivo T1-times well below 1 min. Since helium is not absorbed in considerable amounts, its application is restricted to the lung. Xe-129 is also under investigation for imaging of white matter disease and functional studies of cerebral perfusion. Magnetic resonance imaging using hyperpolarized gases is emerging as a technical challenge and opportunity for the MR community. Preliminary experience suggests potential for functional imaging of pulmonary ventilation and cerebral perfusion. PMID:9601972

  3. [CFC gases in medicinal sprays].

    PubMed

    Pedersen, P H; Svendsen, U G

    1989-03-20

    In 1987, approximately 1.18 million aerosol dispensers for medicinal use were sold in Denmark. These contained approximately 29 tons of completely halogenized CFC gases ("Freon") and the preparations were employed for the treatment of bronchial asthma and rhinitis. The possibilities of substitutes are discussed in this article. Preparations are already available which do not contain CFC. Producers of CFC are also attempting to develop new aerosol gases which do not damage the environment. Perhaps these will be found in medicinal preparations in the future. PMID:2711484

  4. 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.

  5. Instantaneous and efficient surface wave excitation of a low pressure gas or gases

    DOEpatents

    Levy, Donald J. (Berkeley, CA); Berman, Samuel M. (San Francisco, CA)

    1988-01-01

    A system for instantaneously ionizing and continuously delivering energy in the form of surface waves to a low pressure gas or mixture of low pressure gases, comprising a source of rf energy, a discharge container, (such as a fluorescent lamp discharge tube), an rf shield, and a coupling device responsive to rf energy from the source to couple rf energy directly and efficiently to the gas or mixture of gases to ionize at least a portion of the gas or gases and to provide energy to the gas or gases in the form of surface waves. The majority of the rf power is transferred to the gas or gases near the inner surface of the discharge container to efficiently transfer rf energy as excitation energy for at least one of the gases. The most important use of the invention is to provide more efficient fluorescent and/or ultraviolet lamps.

  6. Failure of activated charcoal to reduce the release of gases produced by the colonic flora

    Microsoft Academic Search

    Fabrizis L Suarez; Julie Furne; John Springfield; Michael D Levitt

    1999-01-01

    Objective: Activated charcoal is used to treat excessive volume or malodor of intestinal gas. Our previous studies demonstrated that activated charcoal failed to bind appreciable quantities of the volumetrically important gut gases. However, the odor of feces and flatus derives primarily from trace quantities of sulfur-containing gases, primarily H2S and methanethiol, which should avidly bind to activated charcoal. The goal

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

    Microsoft Academic Search

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

    2008-01-01

    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)

  8. Process gases for laser welding

    Microsoft Academic Search

    Mark Faerber; Joachim Berkmann

    1997-01-01

    To achieve a high return on investment, laser systems must be used to their fullest capacity, avoiding power losses and downtimes. High-quality laser gases are therefore needed to run the laser. But if the quality of the gas cannot be guaranteed all the way from the cylinder to the laser cavity, the risk of impurities such as water vapor and

  9. 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.

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

    SciTech Connect

    Donko, Z. [Research Inst. for Solid State Physics of the Hungarian Academy of Sciences, Budapest (Hungary)

    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.

  11. Laser driven electron acceleration in vacuum, gases and plasmas

    SciTech Connect

    Sprangle, P.; Esarey, E.; Krall, J.

    1996-04-19

    This paper discusses some of the important issues pertaining to laser acceleration in vacuum, neutral gases and plasmas. The limitations of laser vacuum acceleration as they relate to electron slippage, laser diffraction, material damage and electron aperture effects, are discussed. An inverse Cherenkov laser acceleration configuration is presented in which a laser beam is self guided in a partially ionized gas. Optical self guiding is the result of a balance between the nonlinear self focusing properties of neutral gases and the diffraction effects of ionization. The stability of self guided beams is analyzed and discussed. In addition, aspects of the laser wakefield accelerator are presented and laser driven accelerator experiments are briefly discussed.

  12. High order harmonic generation in rare gases

    SciTech Connect

    Budil, K.S.

    1994-05-01

    The process of high order harmonic generation in atomic gases has shown great promise as a method of generating extremely short wavelength radiation, extending far into the extreme ultraviolet (XUV). The process is conceptually simple. A very intense laser pulse (I {approximately}10{sup 13}-10{sup 14} W/cm{sup 2}) is focused into a dense ({approximately}10{sup l7} particles/cm{sup 3}) atomic medium, causing the atoms to become polarized. These atomic dipoles are then coherently driven by the laser field and begin to radiate at odd harmonics of the laser field. This dissertation is a study of both the physical mechanism of harmonic generation as well as its development as a source of coherent XUV radiation. Recently, a semiclassical theory has been proposed which provides a simple, intuitive description of harmonic generation. In this picture the process is treated in two steps. The atom ionizes via tunneling after which its classical motion in the laser field is studied. Electron trajectories which return to the vicinity of the nucleus may recombine and emit a harmonic photon, while those which do not return will ionize. An experiment was performed to test the validity of this model wherein the trajectory of the electron as it orbits the nucleus or ion core is perturbed by driving the process with elliptically, rather than linearly, polarized laser radiation. The semiclassical theory predicts a rapid turn-off of harmonic production as the ellipticity of the driving field is increased. This decrease in harmonic production is observed experimentally and a simple quantum mechanical theory is used to model the data. The second major focus of this work was on development of the harmonic {open_quotes}source{close_quotes}. A series of experiments were performed examining the spatial profiles of the harmonics. The quality of the spatial profile is crucial if the harmonics are to be used as the source for experiments, particularly if they must be refocused.

  13. Emissions of greenhouse gases in the United States 1997

    SciTech Connect

    NONE

    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.

  14. Precise determination of refractometric parameters for atmospheric gases

    SciTech Connect

    Birch, K.P. (National Physical Lab., Middlesex (United Kingdom))

    1991-04-01

    The increasing use of laser interferometers for ultraprecise length measurements in the free atmosphere has produced a corresponding requirement for the accurate determination of the refractive index of ambient air. Consequently the National Physical Laboratory (NPL) (Teddington, UK) has developed an automatic interference air refractometer sensors for this purpose. The measurement of refractive-index variations of gases at different wavelengths, temperatures, and pressures also has high importance, for example, by enhancing the understanding of the molecular structures involved. Therefore the NPL's air refractometer was also used for determining refractive indices and other associated refractometric parameters of a range of atmospheric gases from which a study was made on the validity of the Lorentz-Lorentz equation when applied to air. The gases that were studied at a wavelength of 633 nm were nitrogen, oxygen, argon, carbon dioxide, neon, helium, nitrous oxide (N{sub 2}O), krypton, and dry air.

  15. Toxicity of pyrolysis gases from polypropylene

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Schneider, J. E.; Brauer, D. F.

    1979-01-01

    A sample of polypropylene was evaluated for toxicity of pyrolysis gases, using the toxicity screening test method developed at the University of San Francisco. The gases from this sample appeared to be equivalent or less toxic than the gases from a sample of polyethylene under these particular test conditions. Carbon monoxide appeared to be the principal toxicant.

  16. Chemistry of Carbon Gases in Volcanic Gases on Io

    NASA Astrophysics Data System (ADS)

    Schaefer, L.; Fegley, B., Jr.

    2004-11-01

    We use chemical equilibrium calculations to model the chemistry of carbon in volcanic gases on Io (Schaefer and Fegley 2004, ApJ, in review). The calculations covered temperatures from 500 - 2000 K, pressures from 10-8 to 10+2 bars, and bulk O/S atomic ratios from ˜ 0 to 3. These conditions overlap the nominal conditions at Pele, where T = 1760 K, P = 0.01 bar, and O/S ˜ 1.5. Bulk C/S atomic ratios ranging from 10-4 to 10-1 are used in the equilibrium calculations, with a nominal value of 10-3 based upon upper limits for carbon on Io from Voyager observations of the Loki plume. Carbon monoxide and CO2 are the two major carbon gases under nearly all conditions studied. Carbonyl sulfide and CS2 are orders of magnitude less abundant. Consideration of different loss processes including photolysis, condensation, and kinetic reactions in the plume indicates that photolysis is probably the major loss process for all gases. Both CO and CO2 should be observable in volcanic plumes and in Io's atmosphere at abundances of several hundred parts per million by volume for a bulk C/S atomic ratio of 10-3. This work is supported by the NASA Planetary Atmospheres program.

  17. Radiative properties of char, fly-ash, and soot particles in coal flames. Technical progress report, 2nd year, September 15, 1993--September 15, 1994

    SciTech Connect

    Menguec, M.P.; Manickavasagam, S.; Ghosal, S.; Govindan, R.

    1994-12-01

    A detailed understanding of pulverized-coal combustion process is crucial to developing more efficient and cost-effective combustion chambers and furnaces that use coal as the primary source of energy. Several complicated phenomena occur simultaneously in pulverized-coal flames, and radiation heat transfer is only one of them. However, the contribution of radiation to total heat transfer can be as high as 90% at large-scale pulverized-coal fired furnaces. Because of this, modeling of radiation heat transfer requires special consideration. In predicting the radiative heat flux distribution in combustion systems, three important problems must be considered simultaneously: (i) mathematical formulation and solution of the radiative transfer equation (RTE), (ii) modeling of spectrally banded radiation from the combustion gases, and (iii) modeling of continuum radiation from the particles such as pulverized coal, char, fly-ash, and soot in the combustion products. The accuracy of the solution to the RTE depends on the accuracy of the radiative properties of the medium used in the analysis. Mathematical models for the radiative properties of combustion gases, such as water vapor and carbon dioxide, are well established. Particle radiative properties, i.e. for pulverized coal, fly-ash, and soot, are more critical than those of combustion gases, because particles absorb, emit and scatter radiation within the entire wavelength spectrum, while gases contribute only in certain spectral bands. State-of-the-art reviews of the radiative property data of particles have been given by Viskanta and Menguec (1987), Sarofim (1988), Blokh (1988), and Menguec and Webb (1993). It is sufficient to say that there is no agreement between different researchers on the complex index of refraction of coal/char and soot particles; although, for fly-ash particles the available data are quite reliable (Goodwin, 1986).

  18. Synchrotron radiation - Applications in the earth sciences

    NASA Technical Reports Server (NTRS)

    Bassett, W. A.; Brown, G. E., Jr.

    1990-01-01

    Synchrotron-radiation sources and their characteristics are overviewed along with recent synchrotron-based research on earth materials and future earth-science applications utilizing the next generation of synchrotron-radiation sources presently under construction. Focus is placed on X-ray scattering studies of earth materials (crystalline and noncrystalline) under ambient conditions, diffraction studies of earth materials at high pressures and/or temperatures, spectroscopic studies, primarily X-ray absorption spectroscopy, and spatially resolved X-ray fluorescence studies of compositional variations in earth materials. It is noted that other synchrotron-based methods, such as X-ray tomography and topography may become important in characterizing earth materials, while soft X-ray/vacuum ultraviolet radiation from synchrotron sources can be applied to problems involving the structural environments of low-atomic-number elements and the characterization of surface reactions of minerals with liquids and gases.

  19. Catalyst for purifying exhaust gases

    SciTech Connect

    Fujitani, Y.; Kondoh, S.; Muraki, H.; Nakamura, T.; Sobukawa, H.; Tomita, M.; Yokota, K.

    1982-02-23

    A catalyst for reducing nitrogen oxides, carbon monoxide and hydrocarbons, the noxious components in exhaust gases from internal combustion engines, etc., is disclosed comprising: a porous carrier of ceramic selected from the group consisting of alumina and alumina-magnesia spinel; and a catalyst ingredient supported thereon consisting essentially of zirconium oxide, cerium oxide and a metal selected from the group consisting of platinum, palladium and mixtures thereof.

  20. Thermomagnetic Force in Polyatomic Gases 

    E-print Network

    Larchez, M. E.; Adair, Thomas W.

    1971-01-01

    . Since then extensive investigations have been conducted on these field effects [now called Senftleben-Beenakker (SB}effects] in nu- merous gases. A comprehensive review and bib- liography of the experimental and theoretical work in this field can... in place were identical to those made without it. IV. DISCUSSION OF RESULTS The thermomagnetic-force effect reported here may be compared to the Senftleben-Beenakker (SB) effect. The force effect approaches a maxi- mum as a universal function of H...

  1. 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

  2. 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.

  3. Effect of photolysis on seeding gases in a TEA CO2 laser

    NASA Astrophysics Data System (ADS)

    Kim, C.-M.; Kim, Y.

    1985-04-01

    In the reported investigation regarding the effects of photolysis on seeding gases in a TEA carbon dioxide laser, use is made of normal-propylalcohol (NPA) and isopropyl alcohol (IPA). NPA and IPA have similar ionization potentials, and under UV irradiation they are dissociated into their subseeding gases. On the basis of the obtained results, it is concluded that the photolysis of seeding gases and the ionization potential of the new subseeding gases play an important part in the production of the electron density in a CO2 laser using seeding gases. It is pointed out that until now, tri-n-propylamine has been used as the best suited seeding gas. It is proposed to select a more effective seeding gas than tri-n-propylamine on the basis of a survey of the ionization potentials.

  4. Investigation of ultrafast laser-driven radiative blast waves.

    PubMed

    Edwards, M J; MacKinnon, A J; Zweiback, J; Shigemori, K; Ryutov, D; Rubenchik, A M; Keilty, K A; Liang, E; Remington, B A; Ditmire, T

    2001-08-20

    We have examined the evolution of cylindrically symmetric blast waves produced by the deposition of femtosecond laser pulses in gas jets. In high- Z gases radiative effects become important. We observe the production of an ionization precursor ahead of the shock front and deceleration parameters below the adiabatic value of 1/2 (for a cylinder), an effect expected when the blast wave loses energy by radiative cooling. Despite significant radiative cooling, the blast waves do not appear to develop thin shell instabilities expected for strongly radiative waves. This is believed to be due to the stabilizing effect of a relatively thick blast wave shell resulting in part from electron thermal conduction effects. PMID:11497951

  5. Importance of Minimum Tumor Temperature in Determining Early and Long-Term Responses of Spontaneous Canine and Feline Tumors to Heat and Radiation1

    Microsoft Academic Search

    Mark W. Dewhirst; Dalice A. Sim; Stephen Sapareto; William G. Connor

    1984-01-01

    A total of 130 dogs and cats with squamous cell carcinomas, melanomas, fibrosarcomas, mammary adenocarcinomas, or mast cell sarcomas were randomized to receive radiation (XRT) or heat plus XRT. Time-temperature data for each monitored tumor location were converted to degree-minutes or equivalent min at 43°(Eq43). Response rates and durations of response were compared for subgroups of histology, volume, site, and

  6. 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. [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Feigenberg, Steven J. [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Indelicato, Daniel J. [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Morris, Christopher G. [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Lightsey, Judith [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Grobmyer, Stephen R. [Department of Surgery, University of Florida College of Medicine, Gainesville, FL (United States); Copeland, Edward M. [Department of Surgery, University of Florida College of Medicine, Gainesville, FL (United States); Mendenhall, Nancy P. [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States)]. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Vertical structure and horizontal gradients of aerosol extinction coefficients over coastal India inferred from airborne lidar measurements during the Integrated Campaign for Aerosol, Gases and Radiation Budget (ICARB) field campaign

    NASA Astrophysics Data System (ADS)

    Satheesh, S. K.; Krishna Moorthy, K.; Suresh Babu, S.; Vinoj, V.; Nair, Vijayakumar S.; Naseema Beegum, S.; Dutt, C. B. S.; Alappattu, D. P.; Kunhikrishnan, P. K.

    2009-03-01

    Quantitative estimates of the vertical structure and the spatial gradients of aerosol extinction coefficients have been made from airborne lidar measurements across the coastline into offshore oceanic regions along the east and west coasts of India. The vertical structure revealed the presence of strong, elevated aerosol layers in the altitude region of ˜2-4 km, well above the atmospheric boundary layer (ABL). Horizontal gradients also showed a vertical structure, being sharp with the e-1 scaling distance (D0H) as small as ˜150 km in the well-mixed regions mostly under the influence of local source effects. Above the ABL, where local effects are subdued, the gradients were much shallower (˜600-800 km); nevertheless, they were steep compared to the value of ˜1500-2500 km reported for columnar AOD during winter. The gradients of these elevated layers were steeper over the east coast of India than over the west coast. Near-simultaneous radio sonde (Vaisala, Inc., Finland) ascents made over the northern Bay of Bengal showed the presence of convectively unstable regions, first from surface to ˜750-1000 m and the other extending from 1750 to 3000 m separated by a stable region in between. These can act as a conduit for the advection of aerosols and favor the transport of continental aerosols in the higher levels (>2 km) into the oceans without entering the marine boundary layer below. Large spatial gradient in aerosol optical and hence radiative impacts between the coastal landmass and the adjacent oceans within a short distance of <300 km (even at an altitude of 3 km) during summer and the premonsoon is of significance to the regional climate.

  11. 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

  12. A Radiation Algorithm with Correlated-k Distribution. Part I: Local Thermal Equilibrium.

    NASA Astrophysics Data System (ADS)

    Li, J.; Barker, H. W.

    2005-02-01

    A new radiation scheme is proposed that uses the correlated-k distribution (CKD) method. The definition of the k-distribution function, the transformation between frequency space and k space, and the upper limit of the absorption coefficient in cumulative probability space (CPS) are discussed. The corresponding relation between each interval in CPS and the heating rate profile provides a method for determining the width of intervals in CPS. Three schemes are discussed for handling the spectral overlap of gases. Method 1 rearranges the appropriate combination of gaseous absorption coefficients when the spectral overlap of two gases is extensive. Method 2 applies to most overlapping gases and addresses the most important aspects of each gas's spectrum in each interval of CPS. Method 3 applies to weak gases only and seeks to adjust the main absorption coefficients in order that radiative forcing at the surface and the top of the atmosphere is correct. This model is quite efficient because 1) relatively few intervals in CPS are used (up to 1 mb, only 35 intervals for solar radiation, and 46 for infrared); 2) for some intervals with very large absorption coefficients, the radiative transfer process is simplified by ignoring scattering; 3) the water vapor continuum is dealt with efficiently by neglecting its effect in some nonimportant intervals in CPS and at high altitudes; and 4) gaseous overlap methods are simple and effective. Moreover, this model contains a proper treatment of spectral overlap between solar and infrared radiation. For both solar and infrared radiation, heating rate errors are generally less than 0.2 K day-1, and errors in flux at the surface and the top of the atmosphere are generally less than 1 W m-2.

  13. Anti-pollution device for exhaust gases

    Microsoft Academic Search

    1980-01-01

    An anti-pollution device includes a cylindrical chamber attached in line with the exhaust of an automotive vehicle, which in conjunction with the velocity and heat of emitted exhaust gases further heats and burns emitted gases exiting the tail pipe into relatively harmless non-polluted vapors. The chamber is affixed in line with the exhaust tail pipe of an automotive vehicle near

  14. Wet removal of highly soluble gases

    Microsoft Academic Search

    Peter Brimblecombe; G. A. Dawson

    1984-01-01

    Partition, not kinetics, ultimately determines the concentration of highly soluble gases in cloud droplets. Partition equations are formulated and applied to idealized air-mass thunderclouds and precipitating stratus. Contribution to aqueous concentrations from sub-cloud scavenging of highly soluble gases is estimated at between 10 and 20% under relatively unpolluted conditions. Data indicate that evaporation can produce enhancements in concentration of as

  15. 46 CFR 147.60 - Compressed gases.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...hazardous ships' stores that are compressed gases must be— (1...must be vented to the open air near the top and bottom for...containing ships' stores that are compressed gases must— (1) Be constructed...2) Carry only nitrogen or air, unless permission is...

  16. 46 CFR 147.60 - Compressed gases.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...hazardous ships' stores that are compressed gases must be— (1...must be vented to the open air near the top and bottom for...containing ships' stores that are compressed gases must— (1) Be constructed...2) Carry only nitrogen or air, unless permission is...

  17. 46 CFR 147.60 - Compressed gases.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...hazardous ships' stores that are compressed gases must be— (1...must be vented to the open air near the top and bottom for...containing ships' stores that are compressed gases must— (1) Be constructed...2) Carry only nitrogen or air, unless permission is...

  18. 46 CFR 147.60 - Compressed gases.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...hazardous ships' stores that are compressed gases must be— (1...must be vented to the open air near the top and bottom for...containing ships' stores that are compressed gases must— (1) Be constructed...2) Carry only nitrogen or air, unless permission is...

  19. 46 CFR 147.60 - Compressed gases.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...hazardous ships' stores that are compressed gases must be— (1...must be vented to the open air near the top and bottom for...containing ships' stores that are compressed gases must— (1) Be constructed...2) Carry only nitrogen or air, unless permission is...

  20. Terahertz pulse generation from noble gases

    SciTech Connect

    Chen Yunqing; Yamaguchi, Masashi; Wang Mingfeng; Zhang, X.-C. [Center for Terahertz Research, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2007-12-17

    Terahertz pulse generation in the laser-induced plasma from a series of noble gases (He, Ne, Ar, Kr, and Xe) was systematically investigated. Femtosecond laser pulses consisting of both a fundamental and its second-harmonic frequency were used for the terahertz generation. Experimental results reveal that terahertz generation efficiency of these noble gases increases with decreasing ionization potential.

  1. Toxicity of pyrolysis gases from polyoxymethylene

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Schneider, J. E.; Brauer, D. P.

    1979-01-01

    A sample of polyoxymethylene was evaluated for toxicity of pyrolysis gases, using the toxicity screening test method developed at the University of San Francisco. Under several test conditions, this material gave shorter times to death than many other synthetic polymers. Carbon monoxide appeared to be the principal toxicant in the pyrolysis gases.

  2. 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.

  3. Enhancement of Laser-Induced Fluorescence by Intense Terahertz Pulses in Gases

    Microsoft Academic Search

    Jingle Liu; Xi-Cheng Zhang

    2011-01-01

    The enhancement of laser-induced fluorescence by in- tense terahertz pulses was studied both theoretically and experi- mentally using selected gases. Semiclassical physical picture incor- porating photoionization, electron heating, impact excitation, and dissociative recombination was used to explain the plasma dynam- ics under terahertz radiation in picosecond scale. The dependences of enhanced fluorescence on the terahertz field, laser intensity, and atomic

  4. 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.

  5. Sun and dust versus greenhouse gases: an assessment of their relative roles in global climate change

    Microsoft Academic Search

    James E. Hansen; Andrew A. Lacis

    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.

  6. Hyperpolarized noble gases as contrast agents.

    PubMed

    Zhou, Xin

    2011-01-01

    Hyperpolarized noble gases ((3)He and (129)Xe) can provide NMR signal enhancements of 10,000 to 100,000 times that of thermally polarized gases and have shown great potential for applications in lung magnetic resonance imaging (MRI) by greatly enhancing the sensitivity and contrast. These gases obtain a highly polarized state by employing a spin exchange optical pumping technique. In this chapter, the underlying physics of spin exchange optical pumping for production of hyperpolarized noble gases is explained and the basic components and procedures for building a polarizer are described. The storage and delivery strategies of hyperpolarized gases for in vivo imaging are discussed. Many of the problems that are likely to be encountered in practical experiments and the corresponding detailed approaches to overcome them are also discussed. PMID:21874479

  7. 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

  8. Historical evolution of radiative forcing of climate

    Microsoft Academic Search

    Gunnar Myhre; Arne Myhre; Frode Stordal

    2001-01-01

    We have compiled the evolution of the radiative forcing for several mechanisms based on our radiative transfer models using a variety of information sources to establish time histories. The anthropogenic forcing mechanisms considered are well-mixed greenhouse gases, ozone, and tropospheric aerosols (direct and indirect effect). The natural forcing mechanisms taken into account are the radiative effects of solar irradiance variation

  9. 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

  10. 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

  11. On the Importance of Searching for Oscillations of the Jovian Inner Radiation Belt with a Quasi-Period of 40 Minutes

    E-print Network

    Lou, Y Q; Lou, Yu-Qing; Zheng, Chen

    2003-01-01

    Experiments aboard the Ulysses spacecraft discovered quasi-periodic bursts of relativistic electrons and of radio emissions with ~40-minute period(QP-40) from the south pole of Jupiter in February 1992. Such polar QP-40 burst activities were found to correlate well with arrivals of high-speed solar winds at Jupiter. We advance the physical scenario that the inner radiation belt(IRB) within ~2-3 Jupiter's radius, where ralativistic electrons are known to be trapped via synchrotron emissions, can execute global QP-40 magnetoinertial oscillations excited by arrivals of high-speed solar winds. Modulated by such QP-40 IRB oscillations, relativistic electrons trapped in the IRB may escape from the magnetic circumpolar regions during a certain phase of each 40-min period to form circumpolar QP-40 electron bursts. Highly beamed synchrotron emissions from such QP-40 burst electrons with small pitch angles relative to Jovian magnetic field at ~30-40 Jupiter radius give rise to QP-40 radio bursts with typical frequencie...

  12. On the Importance of Searching for Oscillations of the Jovian Inner Radiation Belt with a Quasi-Period of 40 Minutes

    E-print Network

    Yu-Qing Lou; Chen Zheng

    2003-07-14

    Experiments aboard the Ulysses spacecraft discovered quasi-periodic bursts of relativistic electrons and of radio emissions with ~40-minute period(QP-40) from the south pole of Jupiter in February 1992. Such polar QP-40 burst activities were found to correlate well with arrivals of high-speed solar winds at Jupiter. We advance the physical scenario that the inner radiation belt(IRB) within ~2-3 Jupiter's radius, where ralativistic electrons are known to be trapped via synchrotron emissions, can execute global QP-40 magnetoinertial oscillations excited by arrivals of high-speed solar winds. Modulated by such QP-40 IRB oscillations, relativistic electrons trapped in the IRB may escape from the magnetic circumpolar regions during a certain phase of each 40-min period to form circumpolar QP-40 electron bursts. Highly beamed synchrotron emissions from such QP-40 burst electrons with small pitch angles relative to Jovian magnetic field at ~30-40 Jupiter radius give rise to QP-40 radio bursts with typical frequencies <0.2MHz. We predict that the synchrotron brightness of the IRB should vary on QP-40 timescales upon arrivals of high-speed solar winds with estimated magnitudes larger than 0.1Jy, detectable by ground-based radio telescopes. Using the real-time solar wind data from the spacecraft ACE, we show here that shch QP-40 pulsations of Jupiter's polar X-ray hot spot did in fact coincide with the arrival of high-speed solar wind at Jupiter.

  13. Laser driven acceleration in vacuum and gases

    SciTech Connect

    Sprangle, P.; Esarey, E. [Beam Physics Branch, Plasma Physics Division Naval Research Laboratory, Washington, District of Columbia (United States) 20375; Hafizi, B. [Icarus Research, Inc., P.O. Box 30780, Bethesda, Maryland (United States) 20824-0780; Hubbard, R.; Krall, J.; Ting, A. [Beam Physics Branch, Plasma Physics Division Naval Research Laboratory, Washington, District of Columbia (United States) 20375

    1997-03-01

    Several important issues pertaining to particle acceleration in vacuum and gases are discussed. The limitations of laser vacuum acceleration as they relate to electron slippage, laser diffraction, material damage, and electron aperture effects are presented. Limitations on the laser intensity and particle self-fields due to material breakdown are quantified. In addition, the reflection of the self-fields associated with the accelerated particles places a limit on the number of particles. Two configurations for the inverse Cherenkov accelerator (ICA) are considered, in which the electromagnetic driver is propagated in a waveguide that is (i) lined with a dielectric material or (ii) filled with a neutral gas. The acceleration gradient in the ICA is limited by tunneling and collisional ionization in the dielectric liner or gas. Ionization can lead to significant modification of the optical properties of the waveguide, altering the phase velocity and causing particle slippage, thus disrupting the acceleration process. Maximum accelerating gradients and pulse durations are presented for a 10 {mu}m and a 1 mm wavelength driver. We show that the use of an unguided Bessel (axicon) beam can enhance the energy gain compared to a higher order Gaussian beam. The enhancement factor is N{sup 1/2}, where N is the number of lobes in the Bessel beam. {copyright} {ital 1997 American Institute of Physics.}

  14. Light Collection in Liquid Noble Gases

    SciTech Connect

    McKinsey, Dan [Yale University

    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.

  15. Radiation Therapy

    MedlinePLUS

    ... esophagitis . Since your body uses a lot of energy to heal during radiation therapy, it is important ... surprised if you are more tired, have less energy, or feel weak. Once you have finished treatment, ...

  16. 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.

  17. 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.

  18. 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.

  19. Industrial Gases as a Vehicle for Competitiveness

    E-print Network

    Dale, J. R.

    and power. Improvements in air separation technology have resulted in a marked decrease in the cost of nitrogen and oxygen production. The use of those gases in industrial applications has resulted in energy savings. Several cases are reviewed to show... the unprecedented spiral of cost increases in order to maintain or improve our competitive position in domestic and world markets. Nitrogen, oxygen and argon are considered the bulk gases in our business. I will be focusing my comments on nitrogen and oxygen...

  20. 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.

  1. Extended thermodynamics of molecular ideal gases

    NASA Astrophysics Data System (ADS)

    Kremer, G. M.

    1989-02-01

    The theory of extended thermodynamics developed by Liu and Miller (1983) and Kremer (1986) is applied to the molecular ideal gases. Consideration is given to the formulations for thermodynamic processes, the constitutive theory, the definition of equilibrium, the entropy principle, the principle of material-frame indifference, the identification of absolute temperature and transport coefficients, and the consequences of the entropy inequality. The relationships between this extended theory and both conventional thermodynamics and the kinetic theory of molecular gases are explored.

  2. Consistent sets of atmospheric lifetimes and radiative forcings on climate for CFC replacements: HCFCs and HFCs

    NASA Astrophysics Data System (ADS)

    Naik, Vaishali; Jain, Atul K.; Patten, Kenneth O.; Wuebbles, Donald J.

    2000-03-01

    Recognition of deleterious effects of chlorine and bromine on ozone and climate over the last several decades has resulted in international accords to halt the production of chlorine-containing chlorofluorocarbons (CFCs) and bromine-containing halons. It is well recognized, however, that these chemicals have had important uses to society, particularly as refrigerants, as solvents, as plastic blowing agents, as fire retardants and as aerosol propellants. This has led to an extensive search for substitute chemicals with appropriate properties to be used in place of the CFCs and halons. The purpose of this study is to evaluate in a consistent manner the atmospheric lifetime and radiative forcing on climate for a number of replacement compounds. The unique aspect of this study is its attempt to resolve inconsistencies in previous evaluations of atmospheric lifetimes and radiative forcings for these compounds by adopting a uniform approach. Using the latest version of our two-dimensional chemical-radiative-transport model of the global atmosphere, we have determined the atmospheric lifetimes of 28 hydrohalocarbons (HCFCs and HFCs). Through the comparison of the model-calculated lifetimes with lifetimes derived using a simple scaling method, our study adds to earlier findings that consideration of stratospheric losses is important in determining the lifetimes of gases. Discrepancies were found in the reported lifetimes of several replacement compounds reported in the international assessment of stratospheric ozone published by the World Meteorological Organization [Granier et al., 1999] and have been resolved. We have also derived the adjusted and instantaneous radiative forcings for CFC-11 and 20 other halocarbons using our radiative transfer model. The sensitivity of radiative forcings to the vertical distribution of these gases is investigated in this study and is shown to be significant. The difference in the global radiative forcing arising from the assumption of a constant vertical profile for these gases is found to range from 0 to 36%, with higher difference for short-lived gases. Global Warming Potentials (GWPs) for the compounds are determined using the lifetimes and radiative forcings evaluated in this study and are found to differ from values reported by Granier et al. [1999] owing to the differences in our calculated radiative forcings and lifetimes.

  3. 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.

  4. FTIR spectroscopy for the determination of water in corrosive gases

    SciTech Connect

    Rowe, R.K.; Stallard, B.R. [Sandia National Labs., Albuquerque, NM (United States); Espinoza, L.H.; Niemczyk, T.M. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Chemistry

    1994-07-01

    Internal corrosion in semiconductor gas delivery systems may lead to increased particle counts in downstream fabrication tools and to catastrophic failure of the delivery system itself. The problem is particularly acute since, once the corrosion begins, it becomes a moisture reservoir to further damage the system. To keep gas systems as moisture free as possible semiconductor manufacturers employ drying filters, usually located just after the source of the process gas. Even so, the piping for corrosive gases may need to be rebuilt every few years. Careful monitoring of the moisture in the process gases can provide valuable information about the state of the gas handling system and its effect on the process integrity. Presently there are several technologies costing $50K or less that are capable of detecting trace water vapor as low as 50 ppb in N{sub 2}. However, no one type of instrument has achieved universal acceptance. In particular, all have limited compatibility with corrosive gases such as HCl and HBr. The goal of this project is to develop an in-line instrument based on infrared spectroscopy for this purpose. Earlier results leave no doubt that FTIR spectroscopy can be successfully used for trace water detection. However, important questions regarding optimal data analysis and instrument design are not yet fully answered. It is the goal of this research effort to answer these questions and to incorporate the findings into a prototype device suitable for commercialization.

  5. Analysis of electron interactions in dielectric gases

    SciTech Connect

    Olivet, Aurelio; Duque, Daniel; Vega, Lourdes F. [Institut de Ciencia de Materials de Barcelona, Consejo Superior de Investigaciones Cientificas (ICMAB-CSIC), Campus de la U.A.B., 08193 Bellaterra (Spain)

    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.

  6. 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.

  7. Metastable Quasimolecules in Excited Gases

    E-print Network

    V. N. Malnev; R. A. Naryshkin

    2008-09-09

    Quasimolecules, which consist of two differently excited atoms in a resonantly excited gas, are considered. The energy of dissociation and typical sizes of such molecules are calculated in the first order of quantum-mechanical perturbation theory with the help of the dipole-dipole interaction operator. It is shown that there exist metastable quasimolecules, whose dipole radiative transition to the ground state (two non-excited atoms) is forbidden. The lifetime of such molecules is estimated and it is shown that quasimolecules may considerably affect the transport processes in a resonantly excited gas.

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

    SciTech Connect

    Seager, S.; Bains, W.; Hu, R. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    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.

  9. 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.

  10. [Imported histoplasmosis].

    PubMed

    Stete, Katarina; Kern, Winfried V; Rieg, Siegbert; Serr, Annerose; Maurer, Christian; Tintelnot, Kathrin; Wagner, Dirk

    2015-06-01

    Infections with Histoplasma capsulatum are rare in Germany, and mostly imported from endemic areas. Infections can present as localized or disseminated diseases in immunocompromised as well as immunocompetent hosts. A travel history may be a major clue for diagnosing histoplasmosis. Diagnostic tools include histology, cultural and molecular detection as well as serology. Here we present four cases of patients diagnosed and treated in Freiburg between 2004 and 2013 that demonstrate the broad range of clinical manifestations of histoplasmosis: an immunocompetent patient with chronic basal meningitis; a patient with HIV infection and fatal disseminated disease; a patient with pulmonary and cutaneous disease and mediastinal and cervical lymphadenopathy; and an immunosuppressed patient with disseminated involvement of lung, bone marrow and adrenal glands. PMID:26069920

  11. Radiative heating in contrail cirrus

    NASA Astrophysics Data System (ADS)

    Schumann, Ulrich; Mayer, Bernhard; Hamann, Ulrich; Graf, Kaspar

    2010-05-01

    In the course of analysis and modeling of aviation induced contrail cirrus, we found that observed time scales of contrail cirrus and thin cirrus in general requires particle losses by radiative heating besides other loss processes. For thin cirrus near the tropopause, radiative warming dominates over cooling in most cases, in particular in the lower part of cirrus layers. Both terrestrial and solar radiances contribute to warming, but the terrestrial part is often the larger one. The radiation is absorbed mainly by the ice particles while a smaller fraction is absorbed by water vapor and other gases inside the cirrus. The heating directly absorbed in the ice particles causes a temperature difference between the ice particles and ambient air. Because of the small heat capacity of the ice particles and because of the small particle scales, local equilibrium between radiative heating and conductive cooling is reached quickly. In agreement with Gierens (1994) and others, this causes a temperature surplus of order 0.1 K for ice particles larger than about 100 micro meters. For smaller particles, the temperature increases about linearly with the particle radius. The contribution is important for very low ice particle concentrations (below 0.1/cm**3) and solar optical depth larger 0.1. After heat exchange with the ambient air, and by additional absorption of radiation in the gas phase, the radiation also causes a bulk warming of the cirrus, again of order 0.1 K. The contribution is important for high ice particle concentrations (> 1 /cm**3) and for rather modest optical depth values (0.01 to 0.1). Quasi equilibrium is reached in proportion to the inverse heating rate, which may take hours. In case of heating the increased ice particle temperature causes reduced water vapor saturation at the ice surface and hence sublimation. Hence, both effects may contribute to a loss of ice particles in cirrus, in particular, when relative humidity inside the cirrus is close to ice saturation. In addition, the radiative heating may cause convective turbulence because of warm air masses rising and cold air masses sinking. Finally, the whole cirrus may rise slowly rise by the diabatic heating. In order to simulate these effects in contrail cirrus we developed an effective model (within our contrail cirrus prediction model, CoCiP) which computes the radiative heating rate in both the longwave and shortwave spectral ranges. The model parameterizes the impact of radiative heating on turbulent mixing and sublimation of ice particles in a thin cirrus layer. The heating rate is modeled as a function of cirrus properties (optical depth, temperature, humidity, effective particle radius, and particle habit), solar radiation, solar zenith angle, and the radiances at the top of the atmosphere (solar direct radiation, reflected solar radiation, and outgoing longwave radiation). The model parameters were determined by least square fits of the model results to the results of forward calculations with the libRadtran system using the DISORT 2.0 solver with 16 streams for about 32000 cases with different atmospheres, surface properties and cloud parameters. The model has been applied for various test cases in comparison to cirrus cover derived from SEVIRI-IR data from Meteosat (MSG) observations. The comparison shows that radiative heating may enhance vertical mixing and reduce the life time of contrail cirrus (and thin cirrus in general) by factors of order two.

  12. Optical Refractivity of High-Temperature Gases. I. Effects Resulting from Dissociation of Diatomic Gases

    Microsoft Academic Search

    Ralph A. Alpher; Donald R. White

    1959-01-01

    Shock-tube and discharge techniques make it possible to generate in the laboratory significant volumes of dissociated and?or ionized gases. This paper describes some studies of the optical index of refraction ? of dissociated diatomic gases. The physical interpretation of specific refractivity K = (? ? 1)?&rgr; is discussed and related to polarizability, and various methods of computing such quantities are

  13. Retrieval of CFC concentrations from thermal infrared spectrum observed by Greenhouse gases Observation SATellite (GOSAT)

    NASA Astrophysics Data System (ADS)

    Inagoya, A.; Imasu, R.; Hayashi, Y.

    2011-12-01

    Chemical substances emitted by the anthropological activities cause serious environmental problems. Among them, CFCs have been depleting ozone layer in the stratosphere. Also, it is reported that their radiative forcing is 0.268 W/m2 and they could largely account for global warming. To mitigate these problems, it is important to estimate their distribution and amount globally with good accuracy. Though on site measurements provide considerably precise data, the observation sites are quite limited. In contrast, results retrieved from data obtained by remote sensing may contain more errors, but its wide spatial coverage is great advantage to monitor atmosphere globally and continuously for long term. The purpose of this study is to retrieve concentrations of CFC-11 and CFC-12, and replacements for CFCs from thermal infrared spectrum data obtained by Greenhouse gases Observation SATellite (GOSAT). We use spectrum data taken from its main sensor, Fourier transform spectrometer TANSO-FTS, particularly its band 4 (5.5 - 14.3?m). The sub-sensor called TANSO-CAI is used for cloud screening. To calculate simulated spectrum using a radiative transfer model, LBLRTM, the meteorological reanalysis data including atmospheric information at each point such as surface temperature and atmospheric composition are prepared. As the first step, we focus on CFC-11 and CFC-12 which have strong absorption band near 850 cm-1 and 920 cm-1 respectably. For retrieving the gases, the baselines of the observed and calculated spectrum need to be matched. However, it is not always true due to the uncertainty of information in the reanalysis data. To match baselines, we first set the constant emissivity and estimate the surface temperature. Even after the procedure, spectral residue still remained particularly on the peaks of water vapor absorption lines. We will retrieve more precise surface temperature and the amount of water vapor from observed each spectrum so that we could get better a priori for gas retrieval. We will also discuss how accurately CFC-11 and CFC-12 can be retrieved by GOSAT data.

  14. The importance of the Montreal Protocol in protecting climate

    PubMed Central

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

    2007-01-01

    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

  15. Airway exchange of highly soluble gases.

    PubMed

    Hlastala, Michael P; Powell, Frank L; Anderson, Joseph C

    2013-03-01

    Highly blood soluble gases exchange with the bronchial circulation in the airways. On inhalation, air absorbs highly soluble gases from the airway mucosa and equilibrates with the blood before reaching the alveoli. Highly soluble gas partial pressure is identical throughout all alveoli. At the end of exhalation the partial pressure of a highly soluble gas decreases from the alveolar level in the terminal bronchioles to the end-exhaled partial pressure at the mouth. A mathematical model simulated the airway exchange of four gases (methyl isobutyl ketone, acetone, ethanol, and propylene glycol monomethyl ether) that have high water and blood solubility. The impact of solubility on the relative distribution of airway exchange was studied. We conclude that an increase in water solubility shifts the distribution of gas exchange toward the mouth. Of the four gases studied, ethanol had the greatest decrease in partial pressure from the alveolus to the mouth at end exhalation. Single exhalation breath tests are inappropriate for estimating alveolar levels of highly soluble gases, particularly for ethanol. PMID:23305981

  16. Pulse Discharge in Mixing Layer of Reacting Gases

    NASA Astrophysics Data System (ADS)

    Leonov, Sergey; Isaenkov, Yuri; Shneider, Michail

    2008-10-01

    A subject of consideration is the dynamic of filamentary pulse discharge generated along contact zone of two co-flown gases. Experimental facility consists of blow-down wind tunnel PWT-50, system of the high-voltage pulse-repetitive feeding, and diagnostic equipment (schlieren device; pressure, voltage, current, radiation sensors; spectroscopic system; etc.) Typical parameters: p=0.2-1Bar, velocity M=0-2, pulse duration ?=0.1-1?s, power release W=20-100MW. Recently the effect of enormously fast turbulent expansion of the post-discharge channel was observed experimentally [S. Leonov, oth., AIAA Paper 2005-0159 and S. Leonov, oth. ``Physics of Plasmas'', v.15, 2007]. In this paper a result of parametrical study of the mixing efficiency due to instability development are discussed. The next announced item is that the discharge position and dynamics depend on the test parameters and physical properties of gases involved. The result of interaction can be controlled by the discharge's duration and current as well as by small additives to the gas. The effects found can be applied for high-speed combustion enhancement due to mixing acceleration in multi-components flow..

  17. 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.

  18. Dark lump excitations in superfluid Fermi gases

    NASA Astrophysics Data System (ADS)

    Xu, Yan-Xia; Duan, Wen-Shan

    2012-11-01

    We study the linear and nonlinear properties of two-dimensional matter-wave pulses in disk-shaped superfluid Fermi gases. A Kadomtsev—Petviashvili I (KPI) solitary wave has been realized for superfluid Fermi gases in the limited cases of Bardeen—Cooper—Schrieffer (BCS) regime, Bose—Einstein condensate (BEC) regime, and unitarity regime. One-lump solution as well as one-line soliton solutions for the KPI equation are obtained, and two-line soliton solutions with the same amplitude are also studied in the limited cases. The dependence of the lump propagating velocity and the sound speed of two-dimensional superfluid Fermi gases on the interaction parameter are investigated for the limited cases of BEC and unitarity.

  19. Using Thermal Infrared Absorption and Emission to Determine Trace Gases

    NASA Astrophysics Data System (ADS)

    Clerbaux, Cathy; Drummond, James R.; Flaud, Jean-Marie; Orphal, Johannes

    The light emerging from the top of the atmosphere in the greater part of the infrared region is thermal radiation from the Earth's surface. The resultant spectra obtained depend on the temperature difference between the emitting feature and absorbing gas. In this region the greenhouse gases, carbon dioxide, CO2, methane, CH4, ozone, O3, and water, H2O, are observed as well as carbon monoxide, CO, a product indicative of fossil fuel combustion, methanol, CH3OH, from biomass burning, and ammonia, NH3, from agriclulture. Chapter 3 describes the techniques for retrieving atmospheric abundances of these and other species from a number of satellite instruments, and concludes with suggestions for future developments.

  20. RADIATION HYBRID MAPPING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Radiation hybrid maps are physical maps of genomes that provide an alternative to traditional genetic maps. These radiation hybrid maps have two important advantages over genetic maps. First, distances on a radiation hybrid map are determined by the frequency of radiation-induced breaks between mark...

  1. Filament-induced ultrafast birefringence in gases

    NASA Astrophysics Data System (ADS)

    Yuan, S.; Li, M.; Feng, Y.; Li, H.; Zheng, L.; Chin, S. L.; Zeng, H.

    2015-05-01

    Femtosecond laser filaments generated by ultrashort laser pulses induce a remarkable birefringence over the whole filament length. Any linearly polarized femtosecond laser pulse probing this filament will be decomposed into two orthogonal polarization components propagating at different speeds resulting in an elliptical polarization. The latter in turn reflects the birefringence inside the filament zone. The filament-induced birefringence could be due to instantaneous electronic or delayed molecular response depending on different types of gases. In this paper, we review recent progress on filament-induced ultrafast birefringence in gases.

  2. Managing biogeochemical cycles to reduce greenhouse gases

    SciTech Connect

    Post, Wilfred M [ORNL; Venterea, Rodney [United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Soil and Water

    2012-01-01

    This special issue focuses on terrestrial biogeochemical cycles as they relate to North America-wide budgeting and future projection of biogenic greenhouse gases (GHGs). Understanding the current magnitude and providing guidance on the future trajectories of atmospheric concentrations of these gases requires investigation of their (i) biogeochemical origins, (ii) response to climate feedbacks and other environmental factors, and (iii) susceptibility to management practices. This special issue provides a group of articles that present the current state of continental scale sources and sinks of biogenic GHGs and the potential to better manage them in the future.

  3. 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.

  4. Radiation effects on resins and zeolites at Three Mile Island Unit II

    Microsoft Academic Search

    J. K. Reilly; P. J. Grant; G. J. Quinn; K. J. Hofstetter

    1984-01-01

    Radiation effects on resin and zeolite used in the waste cleanup at Three Mile Island Unit II have been examined both experimentally and in-situ. Hydrogen and organic gases are generated due to absorbed radiation as a function of resin material, curie loading and residual water content. Significant oxygen scavaging was demonstrated in the organic resin liners. Hydrogen and oxygen gases

  5. Spectral line-based weighted-sum-of-gray-gases model for arbitrary RTE solvers

    SciTech Connect

    Denison, M.K.; Webb, B.W. (Brigham Young Univ., Provo, UT (United States))

    1993-11-01

    This paper presents an approach for generating weighted-sum-of-gray gases (WSGG) models directly from the line-by-line spectra of H[sub 2]O. Emphasis is placed on obtaining detailed spectral division among the gray gases. Thus, for a given model spectrum, the gray gas weights are determined as blackbody fractional functions for specific subline spectral regions at all temperatures. The model allows the absorption coefficient to be the basic radiative property rather than a transmissivity or band absorptance, etc., and can be used with any arbitrary solution method for the Radiative Transfer Equation (RTE). A single absorption cross section spectrum is assumed over the entire spatial domain in order to fix the subline spectral regions associated with a single spectral calculation. The error associated with this assumption is evaluated by comparison with line-by-line benchmarks for problems of nonisothermal and nonhomogeneous media. 28 refs., 7 figs.

  6. What kept early Earth warm? Examining a diverse range of greenhouse gases

    NASA Astrophysics Data System (ADS)

    Byrne, B.; Goldblatt, C.

    2013-12-01

    Over Earth's history the solar constant has increased from 70% of its current value. Over much of this period evidence has been found for a temperate climate and lack of glaciation. Enhancements in a variety of different greenhouse gases, most of which are biogenic, have been suggested to have kept the early Earth warm. However, different modelling approaches (and some model errors) have hampered comparison of different proposals. Here we present initial results of a project to calculate high-accuracy radiative forcings for all proposed greenhouse gases for early Earth (and some that have not previously been proposed). By reducing uncertainties in the radiative transfer calculations, we hope to push forward the debate on what kept early Earth warm, allowing future work to focus more on what biogeochemical processes controlled atmospheric composition.

  7. Gas phase radiative effects in diffusion flames

    Microsoft Academic Search

    Hasan Bedir

    1998-01-01

    Several radiation models are evaluated for a stagnation point diffusion flame of a solid fuel in terms of accuracy and computational time. Narrowband, wideband, spectral line weighted sum of gray gases (SLWSGG), and gray gas models are included in the comparison. Radiative heat flux predictions by the nongray narrowband, wideband, and SLWSGG models are found to be in good agreement

  8. Radiation Symbols

    MedlinePLUS

    Radiation Protection Basics Health Effects Ionizing & Non-Ionizing Radiation Understanding Radiation: Radiation Symbols Radiation Protection Basics Main Page History of Radiation Protection Radiation Warning Symbols Radiation Warning Sign Gallery ...

  9. Process gases for high velocity oxy-fuel thermal spraying

    SciTech Connect

    Creffield, G.K.; Chapman, I.F.; Cole, M.A.; Page, W.J.; McDonough, T. [BOC Group, London (United Kingdom)

    1994-12-31

    The importance of fuel and other process gases for high velocity oxy-fuel (HVOF) thermal spraying and especially the delivery of them to the point of use is well recognized. Problems associated with the supply of liquid fuel gases, at the high flow rates and pressures required by this process, have been addressed. Considerable development work has gone into designing an appropriate liquid withdrawal and vaporizer system for propylene, which overcomes these previous difficulties and enables users to maintain adequate fuel gas flow rates in order to ensure optimum operating conditions for the production of high quality coatings. A feature of the thermal spray process is that the temperature of the workpiece is kept low, typically below 150 C, in order to reduce residual stresses in the coating and to protect heat sensitive substrates. Traditionally this has been by compressed air, however, improved cooling has been achieved using carbon dioxide. Specially designed equipment is now available which provides and directs a cold mixture of carbon dioxide gas and solid particles (snow) via suitable nozzles, on the workpiece. The position of the cooling stream can be varied, depending on the application. These developments emphasize the importance now attached to providing dedicated gas installation packages for HVOF.

  10. Rotational Relaxation in Nonpolar Diatomic Gases

    Microsoft Academic Search

    John A. Lordi; Robert E. Mates

    1970-01-01

    The rotational-translational energy transfer in collisions between homonuclear diatomic molecules and the rotational relaxation time in diatomic gases have been investigated classically. Using Parker's model for the intermolecular potential, numerical solutions were obtained for the rotational-energy transfer in individual collisions. The method of solution for the collision trajectories has been combined with a Monte Carlo integration procedure to evaluate the

  11. Ideal quantum gases in two dimensions

    Microsoft Academic Search

    S. Viefers; F. Ravndal; T. Haugset

    1995-01-01

    Thermodynamic properties of nonrelativistic bosons and fermions in two spatial dimensions and without interactions are derived. All the virial coefficients are the same except for the second, for which the signs are opposite. This results in the same specific heat for the two gases. Existing equations of state for the free anyon gas are also discussed and shown to break

  12. Trapped Fermi gases D. A. Butts1

    E-print Network

    Butts, Daniel

    , spin-polarized Fermi gases, the s-wave scattering amplitude which would domi- nate the behavior, Massachusetts 02254 Received 9 December 1996 We study the properties of a spin-polarized Fermi gas in a harmonic of a comparable gas of distinguishable par- ticles vanishes due to the antisymmetry of the many- fermion wave

  13. 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.

  14. 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)

  15. Gases for increased productivity of laser processing

    Microsoft Academic Search

    M. Faerber; AGA AB

    1995-01-01

    To achieve a high return on investment, laser systems must be used to their fullest capacity, avoiding power losses and downtimes. High-quality laser gases are therefore needed to run the laser. But if the quality of the gas cannot be guaranteed all the way from the cylinder to the laser cavity, the risk of impurities such as water vapour and

  16. On-line laser detection of gases

    Microsoft Academic Search

    F. C. Harbert

    1983-01-01

    Petrochemical plants, platforms, refineries, etc, can now be surveyed by a laser instrument which responds to and measures gases in the beam. Scanning with the beam, which can be up to 1 km in length, permits a complete plant to be covered with a single instrument. Another application uses and instrument mounted on a vehicle or an aircraft moving along

  17. Extended thermodynamics of molecular ideal gases

    Microsoft Academic Search

    G. M. Kremer

    1989-01-01

    The theory of extended thermodynamics developed by Liu and Miller (1983) and Kremer (1986) is applied to the molecular ideal gases. Consideration is given to the formulations for thermodynamic processes, the constitutive theory, the definition of equilibrium, the entropy principle, the principle of material-frame indifference, the identification of absolute temperature and transport coefficients, and the consequences of the entropy inequality.

  18. THERMAL CONDUCTIVITIES OF GASES, METALS, LIQUID METALS

    Microsoft Academic Search

    W. M. Przybycien; D. W. Linde

    1957-01-01

    Graphs on the thermal conductivities of gases (air, Ar, COâ, CO, ; He, Hâ, Kr, Ne, NO, Nâ, Oâ, and Xe), metals (Al Be, Inconel X, ; Types 304, 347, and 446 stainless steel, Ti, U-- Zr alloy, and Zircaloy-2), and ; liquid metals (Na and Na--K alloy) are shown. Densities of liquid Na and Na-K ; are included. (J.E.D.)

  19. Toxicity of pyrolysis gases from foam plastics

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Cumming, H. J.; Casey, C. J.

    1980-01-01

    Twenty-three samples of flexible foams and twelve samples of rigid foams were evaluated for toxicity of pyrolysis gases, using the USF toxicity screening test method. Polychloroprene among the flexible foams, and polystyrene among the rigid foams, appeared to exhibit the least toxicity under these particular test conditions.

  20. Toxicity of pyrolysis gases from polyether sulfone

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Olcomendy, E. M.

    1979-01-01

    A sample of polyether sulfone was evaluated for toxicity of pyrolysis gases, using the toxicity screening test method developed at the University of San Francisco. Animal response times were relatively short at pyrolysis temperatures of 600 to 800 C, with death occurring within 6 min. The principal toxicant appeared to be a compound other than carbon monoxide.

  1. Automated gas chromatographic system for rapid analysis of the atmospheric trace gases methane, carbon dioxide, and nitrous oxide

    Microsoft Academic Search

    N. Loftfield; H. Flessa; F. Beese; J. Augustin

    1997-01-01

    To study the fluxes of the radiative active trace gases CHâ, COâ, and NâO, a gas sampling and analytical device was developed. It is a useful tool for accurate gas sampling in the field and enables the subsequent fully automated analysis of the gas samples in the laboratory. The computer-controlled analytical system consists of a gas chromatograph equipped with a

  2. Climate change and trace gases.

    PubMed

    Hansen, James; Sato, Makiko; Kharecha, Pushker; Russell, Gary; Lea, David W; Siddall, Mark

    2007-07-15

    Palaeoclimate data show that the Earth's climate is remarkably sensitive to global forcings. Positive feedbacks predominate. This allows the entire planet to be whipsawed between climate states. One feedback, the 'albedo flip' property of ice/water, provides a powerful trigger mechanism. A climate forcing that 'flips' the albedo of a sufficient portion of an ice sheet can spark a cataclysm. Inertia of ice sheet and ocean provides only moderate delay to ice sheet disintegration and a burst of added global warming. Recent greenhouse gas (GHG) emissions place the Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. Carbon dioxide (CO2) is the largest human-made climate forcing, but other trace constituents are also important. Only intense simultaneous efforts to slow CO2 emissions and reduce non-CO2 forcings can keep climate within or near the range of the past million years. The most important of the non-CO2 forcings is methane (CH4), as it causes the second largest human-made GHG climate forcing and is the principal cause of increased tropospheric ozone (O3), which is the third largest GHG forcing. Nitrous oxide (N2O) should also be a focus of climate mitigation efforts. Black carbon ('black soot') has a high global warming potential (approx. 2000, 500 and 200 for 20, 100 and 500 years, respectively) and deserves greater attention. Some forcings are especially effective at high latitudes, so concerted efforts to reduce their emissions could preserve Arctic ice, while also having major benefits for human health, agricultural productivity and the global environment. PMID:17513270

  3. Permeation of atmospheric gases through polymer O-rings used in flasks for air sampling

    Microsoft Academic Search

    P. Sturm; M. Leuenberger; C. Sirignano; R. E. M. Neubert; H. A. J. Meijer; R. Langenfelds; W. A. Brand; Y. Tohjima

    2004-01-01

    Permeation of various gases through elastomeric O-ring seals can have important effects on the integrity of atmospheric air samples collected in flasks and measured some time later. Depending on the materials and geometry of flasks and valves and on partial pressure differences between sample and surrounding air, the concentrations of different components of air can be significantly altered during storage.

  4. H3+ as a sequestrator of noble gases in the outer solar nebula

    Microsoft Academic Search

    O. Mousis; F. Pauzat; Y. Ellinger

    2006-01-01

    Noble gases are an important component of the atomic population in the universe. It is generally admitted that these elements are inert and do not participate in molecular structures, except the puzzling X-halides compounds. However, this statement may not be relevant when positive ions are involved, especially is the case of the interstellar medium where positive ions do exist in

  5. Factors affecting the association between ambient concentrations and personal exposures to particles and gases.

    PubMed

    Sarnat, Stefanie Ebelt; Coull, Brent A; Schwartz, Joel; Gold, Diane R; Suh, Helen H

    2006-05-01

    Results from air pollution exposure assessment studies suggest that ambient fine particles [particulate matter with aerodynamic diametergases, are strong proxies of corresponding personal exposures. For particles, the strength of the personal-ambient association can differ by particle component and level of home ventilation. For gases, however, such as ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2), the impact of home ventilation on personal-ambient associations is untested. We measured 24-hr personal exposures and corresponding ambient concentrations to PM2.5, sulfate (SO2-(4)), elemental carbon, O3, NO2, and SO2 for 10 nonsmoking older adults in Steubenville, Ohio. We found strong associations between ambient particle concentrations and corresponding personal exposures. In contrast, although significant, most associations between ambient gases and their corresponding exposures had low slopes and R2 values; the personal-ambient NO2 association in the fall season was moderate. For both particles and gases, personal-ambient associations were highest for individuals spending most of their time in high- compared with low-ventilated environments. Cross-pollutant models indicated that ambient particle concentrations were much better surrogates for exposure to particles than to gases. With the exception of ambient NO2 in the fall, which showed moderate associations with personal exposures, ambient gases were poor proxies for both gas and particle exposures. In combination, our results suggest that a) ventilation may be an important modifier of the magnitude of effect in time-series health studies, and b) results from time-series health studies based on 24-hr ambient concentrations are more readily interpretable for particles than for gases. PMID:16675415

  6. 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

  7. Sellmeier and thermo-optic dispersion formulas for GaSe (Revisited).

    PubMed

    Kato, Kiyoshi; Tanno, Fumihito; Umemura, Nobuhiro

    2013-04-10

    This paper reports high-accuracy Sellmeier and thermo-optic dispersion formulas for GaSe that provide excellent reproduction of the phase-matching conditions for second-, third-, and fourth- harmonic generation of CO2 laser radiation at 10.5910 ?m in the 20°C-200°C range as well as the data points of Feng et al. [Opt. Express16, 9978 (2008)10.1364/OE.16.009978OPEXFF1094-4087] for second-harmonic generation of CO2 laser radiation at 9.5862 ?m and an Er3+:YSGG laser at 2.7960 ?m in the -165°C-230°C range. PMID:23670762

  8. 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...

  9. 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...

  10. 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...

  11. 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 ...

  12. 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.

  13. Pulse radiation of four-element large current radiator

    Microsoft Academic Search

    G. P. Pochanin

    1999-01-01

    One of the most important problems in modern ground penetrating radar design is creating ultra wide band (UWB) antennas for short sounding electromagnetic pulses (SP) of radiation. Important requirements for antennas of this kind are the elimination of “ringing” and efficiency. Promising UWB\\/SP radiators, which satisfy these conditions have been proposed by Harmuth. These radiators are named large current radiators

  14. 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.

  15. Measuring the Isotopic Composition of Solar Wind Noble Gases

    E-print Network

    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

  16. Process for removing sulfur dioxide from flue gases

    Microsoft Academic Search

    M. W. Jr

    1989-01-01

    This patent describes an improvement in a dry process for the removal of sulfur dioxide from flue gases by the addition thereto of hydrated lime containing sugar in a coal combustion unit, wherein the flue gases result from the combustion of a coal in a combustion chamber, and the flue gases are treated in an electrostatic precipitator prior to discharge

  17. 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

  18. 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

  19. Final report on activities and findings under DOE grant “Interactive Photochemistry in Earth System Models to Assess Uncertainty in Ozone and Greenhouse Gases”

    SciTech Connect

    Prather, Michael J. [UCI

    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.

  20. Underground Nuclear Explosions and Release of Radioactive Noble Gases

    NASA Astrophysics Data System (ADS)

    Dubasov, Yuri V.

    2010-05-01

    Over a period in 1961-1990 496 underground nuclear tests and explosions of different purpose and in different rocks were conducted in the Soviet Union at Semipalatinsk and anovaya Zemlya Test Sites. A total of 340 underground nuclear tests were conducted at the Semipalatinsk Test Site. One hundred seventy-nine explosions (52.6%) among them were classified as these of complete containment, 145 explosions (42.6%) as explosions with weak release of radioactive noble gases (RNG), 12 explosions (3.5%) as explosions with nonstandard radiation situation, and four excavation explosions with ground ejection (1.1%). Thirty-nine nuclear tests had been conducted at the Novaya Zemlya Test Site; six of them - in shafts. In 14 tests (36%) there were no RNG release. Twenty-three tests have been accompanied by RNG release into the atmosphere without sedimental contamination. Nonstandard radiation situation occurred in two tests. In incomplete containment explosions both early-time RNG release (up to ~1 h) and late-time release from 1 to 28 h after the explosion were observed. Sometimes gas release took place for several days, and it occurred either through tunnel portal or epicentral zone, depending on atmospheric air temperature.

  1. 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.

  2. Experimental studies concerning the drying of voloxidizer off-gases

    SciTech Connect

    Holland, W.D.; Shah, A.H.; Kaiser, A.F.; McGee, J.C.

    1981-07-01

    The results of an experimental program conducted to aid in the design of a tritium retention system to remove tritiated water from voloxidizer off-gases are presented. The retention system is expected to be a fixed-bed adsorption unit using a commercially available desiccant, such as molecular sieves, to dry the off-gases. The presence of iodine in the off-gas stream somewhat complicates the drying process since some iodine will be retained in the drying bed along with the tritiated water. The present work represents a follow-up to a study in which a small-scale (2-in.-diam by 30-in.-long) packed column of Linde Molecular Sieves (LMS) type 3A was repeatedly loaded and regenerated using a non-radioactive simulated voloxidizer off-gas containing water and iodine vapor. Both water and iodine loadings were measured and the regeneration characteristics of the bed were observed. The following studies were carried out: (1) testing of other desiccants showed LMS type 3A to be superior because of its high water loading and low iodine retention; (2) development of a column-mounted moisture detector; (3) adsorption isotherms; (4) iodine analysis using a commercial oxidant monitor; (5) tests on cartridge-type beds - a series of tests were conducted using three small drying beds connected in series. One further finding of this study was the importance of the clay binder (used in pelletized molecular sieves) in obtaining satisfactory or acceptably low iodine retention.

  3. Laser Driven Electron Acceleration in Vacuum and Neutral Gases*

    NASA Astrophysics Data System (ADS)

    Sprangle, Phillip; Esarey, Eric; Krall, Jonathan; Ting, Antonio

    1996-11-01

    This presentation will cover the important principles and issues pertaining to laser acceleration of electrons in vacuum and neutral gases [1]. The effects of electron slippage, driffraction, instabilities, ionization and material damage will be discussed. For the case of acceleration in vacuum, a crossed laser beam accelerator and vacuum beat wave acelerator configuration are analyzed. For acceleration in neutral gas, a self-guided inverse Cherenkov accelerator (ICA) is analyzed. Finally, it is shown that for a fixed total laser power the energy gain in the conventional ICA can be significantly increased by using a nonideal Bessel (axicon) laser beam instead of a conventional Gaussian beam. * Work supported by Department of Energy and Office of Naval Research. [1] "Laser Driven Electron Acceleration In Vacuum, Gases, and Plasmas", P. Sprangle, E. Esarey, and J. Krall, Phys. Plasmas 3, 2183 (1996); "Vacuum Laser Accelerqation', P. Sprangle, E. Esarey, J. Krall, and A. Ting, Optics Communication 124, 69 (1996); "Laser Acceleration of Electrons in Vacuum", E. Esarey, P. Sprangle, and J. Krall, Phys. Rev. E 52, 5443, (1995).

  4. 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.

  5. On-line laser detection of gases

    SciTech Connect

    Harbert, F.C.

    1983-01-01

    Petrochemical plants, platforms, refineries, etc, can now be surveyed by a laser instrument which responds to and measures gases in the beam. Scanning with the beam, which can be up to 1 km in length, permits a complete plant to be covered with a single instrument. Another application uses and instrument mounted on a vehicle or an aircraft moving along a pipeline searching for gas leaks. The use of lasers permits the detection of gases on-line. A laser operating at the required wavelength produces a beam which surveys the plant; some of the infrared light is scattered form the ground onto a detector adjacent to the laser. Any gas in the beam causes the signal at the detector to fall. Accuracies corresponding to +/- 1.0 ppm can be achieved with response times of 10 milliseconds. (JMT)

  6. 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.

  7. The ice record of greenhouse gases

    Microsoft Academic Search

    D. Raynaud; J. Jouzel; J. M. Barnola; J. Chappellaz; R. J. Delmas; C. Lorius

    1993-01-01

    Gases trapped in polar ice provide our most direct record of the changes in greenhouse gas levels during the past 150,000 years. The best conducted trace-gas records are for CO2 and CH4. The measurements corresponding to the industrial period document the recent changes in growth rate. The variability observed over the last 1000 years constrains the possible feedbacks of a

  8. 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.

  9. 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.

  10. Electrical Breakdown in High-temperature Gases

    Microsoft Academic Search

    D. W. George; H. K. Messerle

    1963-01-01

    RELATIVELY few experimental results are available for the breakdown of high-temperature gases at atmospheric pressure and above. Alston1 has confirmed Paschen's law for air up to 1,100° C and obtained flashover voltages which were independent of electrode material. On the other hand, it is well known from investigations of the decaying properties of freely recovering arcs2 that `thermal' breakdown can

  11. Gases : GasRxnVolumes (10 Variations)

    NSDL National Science Digital Library

    A gas phase reaction takes place in a syringe at a constant temperature and pressure. If the initial volume before reaction is 30 mL and the final volume after the reaction is complete is 15 mL, which of the following reactions took place? (Note: You can assume that you start with stoichiometric amounts of the reactants, the reaction goes to completion and that the gases behave ideally.)

  12. 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.

  13. Solution of Gases in Polyethylene Terephthalate

    Microsoft Academic Search

    Alan S. Michaels; Wolf R. Vieth; James A. Barrie

    1963-01-01

    The solubilities of helium, nitrogen, oxygen, argon, methane, carbon dioxide, and ethane in glassy amorphous and crystalline polyethylene terephthalate have been studied by time-lag and?or static sorption methods. Solubilities of all the gases but ethane were also determined in the rubbery crystalline polymer. The only deviations from Henry's law were displayed by ethane at 25°C and carbon dioxide at 25°

  14. Scanning electron microscopy of cold gases

    NASA Astrophysics Data System (ADS)

    Santra, Bodhaditya; Ott, Herwig

    2015-06-01

    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.

  15. Splitting of inviscid fluxes for real gases

    NASA Technical Reports Server (NTRS)

    Liou, Meng-Sing; Vanleer, Bram; Shuen, Jian-Shun

    1988-01-01

    Flux-vector and flux-difference splittings for the inviscid terms of the compressible flow equations are derived under the assumption of a general equation of state for a real gas in equilibrium. No necessary assumptions, approximations or auxiliary quantities are introduced. The formulas derived include several particular cases known for ideal gases and readily apply to curvilinear coordinates. Applications of the formulas in a TVD algorithm to one-dimensional shock-tube and nozzle problems show their quality and robustness.

  16. Nadir Sounding of Carbon Gases using SCIAMACHY Near Infrared Channels

    NASA Astrophysics Data System (ADS)

    Gimeno García, Sebastián; Schreier, Franz; Lichtenberg, Günter; Slijkhuis, Sander; Hess, Michael; Aberle, Bernd

    The Beer InfraRed Retrieval Algorithm (BIRRA) and Column EstimatoR Vertical InfraRed Sounding Atmosphere (CERVISA) codes have been designed to retrieve vertical column den-sities (VCDs) of atmospheric gases in the near and thermal infrared (NIR,TIR) region of the electromagnetic spectrum by means of non-linear least squares fitting of radiances. As part of the operational SCIAMACHY level 1-2 processor, BIRRA is currently used for the specific retrieval of carbon monoxide (CO) VCDs exploiting the fitting window 4282-4301 cm-1 within the SCIAMACHY channel 8. Using appropriate fitting windows in channel 6, BIRRA also allows to gain information on greenhouse gases such as methane and carbon dioxide. Unfortunately, the increasing number of dead and bad pixels -specially in the NIR channels -reduces the available spectral information and consequently makes the VCDs retrieval more and more challenging. The proper choice of the pixel mask, fitting window, auxiliary fit parameters, as well as the filtering of the Level 2 data is crucial for obtaining a high quality atmospheric product. For validation of BIRRA the closely related CERVISA code is used to retrieve CO and CH4 from nadir infrared sounding data of AIRS, IASI, or TES. BIRRA and CERVISA share a large portion of modules, e.g., for line-by-line absorption and the nonlinear least squares solver; the essential difference is the part of the forward model devoted to radiative transfer through the atmosphere, i.e., Beer's law for the NIR versus Schwarzschild's equation for the TIR. CERVISA retrieval results are compared both to the operational products of the TIR sounder and to the SCIAMACHY-BIRRA product. In this work, we present recent results of carbon monoxide and methane retrievals.

  17. Seeded optical breakdown of molecular and noble gases

    SciTech Connect

    Polynkin, Pavel; Scheller, Maik; Moloney, Jerome V. [College of Optical Sciences, University of Arizona 1630 E. University Blvd., Tucson, Arizona 85721 (United States)

    2012-07-30

    We report experimental results on the dual laser-pulse plasma excitation in various gases at atmospheric pressure. Dilute plasma channels generated through filamentation of ultraintense femtosecond laser pulses in air, argon, and helium are densified through the application of multi-Joule nanosecond heater pulses. Optical breakdown in atomic gases can be achieved for considerably longer delays between femtosecond and nanosecond pulses compared to that in molecular gases. The densification of the seed channel in molecular gases is always accompanied by its fragmentation into discrete bubbles, while in atomic gases the densified channel remains smooth and continuous.

  18. 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.

  19. 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. [Institute of Optoelectronics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland)

    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.

  20. 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.

  1. A comparison of hydrocarbon gases from natural sources in the northwestern United States

    SciTech Connect

    Lorenson, T.D.; Kvenvolden, K.A. (Geological Survey, Menlo Park, CA (United States))

    1993-01-01

    The northwestern United States hosts a remarkable quantity and variety of thermal springs, seeps, and other natural-gas sources. Although many studies have dealt with the liquids and nonhydrocarbon gases emanating from these sources, few have focused on hydrocarbon gases. Of these gases, methane in particular is now recognized as an important reactive trace gas in the Earth's atmosphere that plays a significant role in global warming because of its greenhouse properties. To understand better the magnitude and occurrence of emissions of hydrocarbons from natural sources to the atmosphere, we have begun a survey of these gases throughout the northwestern United States. This area encompasses a number of different tectonic provinces: The Yellowstone hot spot, the northern Basin and Range Province, the Cascade volcanic arc, and the Cascadia subduction complex. Each province hosts springs and seeps with some unique compositions owing to the geological processes operating there. Methane is present in each area at concentration levels ranging from about 2 parts per million by volume (ppm-v) to 95.6 percent (by volume). Hydrothermal activity in the Yellowstone area produces spring gases containing less than 4 percent methane, with carbon dioxide as the balance gas. The Grand Teton National Park area, immediately to the south, has a wide variety of gas compositions with either methane, carbon dioxide, or nitrogen as the primary gas component. Where methane is abundant, higher molecular weight hydrocarbon gases (ethane, ethene, propane, propene, isobutane, and n-butane) are also found in ppm-v concentrations. In the northern Great Basin, thermal springs and seeps typically occur along fault zones at the base of mountain ranges. Methane concentrations range from 0.2 to 47 percent, with higher molecular weight hydrocarbon concentrations from 0 to 3,100 ppm-v. 47 refs., 8 figs., 4 tabs.

  2. 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

  3. Aerothermodynamic radiation studies

    NASA Technical Reports Server (NTRS)

    Donohue, K.; Reinecke, W. G.; Rossi, D.; Marinelli, W. J.; Krech, R. H.; Caledonia, G. E.

    1991-01-01

    We have built and made operational a 6 in. electric arc driven shock tube which alloys us to study the non-equilibrium radiation and kinetics of low pressure (0.1 to 1 torr) gases processed by 6 to 12 km/s shock waves. The diagnostic system allows simultaneous monitoring of shock radiation temporal histories by a bank of up to six radiometers, and spectral histories with two optical multi-channel analyzers. A data set of eight shots was assembled, comprising shocks in N2 and air at pressures between 0.1 and 1 torr and velocities of 6 to 12 km/s. Spectrally resolved data was taken in both the non-equilibrium and equilibrium shock regions on all shots. The present data appear to be the first spectrally resolved shock radiation measurements in N2 performed at 12 km/s. The data base was partially analyzed with salient features identified.

  4. 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.

  5. 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.

  6. Simulating Aerosol-cloud-radiation Feedbacks Over East Asia Using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Wang, J.; Allen, D. J.; Pickering, K. E.; Li, Z.

    2013-12-01

    Aerosols play an important role in climate change through their impact on the radiative balance and hydrological cycle of the atmosphere. Recently much effort has been put into studying the radiative forcing of aerosols in East Asia. In this study, we apply the regional chemistry and transport model, WRF-Chem, to study aerosol radiative forcing over eastern Asia. Four model simulations have been conducted to ascertain the direct and indirect (cloud albedo and cloud lifetime) effects of aerosols on radiation and precipitation. The time period of interest is from Feb 22, 2005 to March 31, 2005 when there were extensive measurements of radiation, trace gases, and aerosol properties available from EAST-AIRE (East Asian Study of Tropospheric Aerosols: An International Regional Experiment ). Measurements from EAST-AIRE site Xianghe, MODIS, CERES, and AERONET are used to assess the performance of the base simulation. The base run shows good agreement with observations, although the model underestimates the aerosol loading in East Asia, especially over highly polluted regions. We compare the base run with the sensitivity runs and investigate the difference in short wave radiation at the surface and the top of atmosphere, cloud properties (cloud fraction, cloud condensation nuclei, effective radius, and liquid water path), and precipitation patterns. Preliminary results indicate that short wave radiation at the surface is reduced by 28 W m-2 at Xianghe site due to the aerosol direct effect.

  7. Transonic Lifting Flows of Pressurized Gases

    NASA Astrophysics Data System (ADS)

    Cramer, Mark; Morrison, Michael

    1997-11-01

    We consider two-dimensional, steady, inviscid transonic flows of pressurized gases over both lifting and nonlifting airfoils. To account for deviations from the ideal gas law we have incorporated a state of the art equation of state known as the Martin-Hou equation. Numerical Solutions are generated through use of a conventional finite volume scheme. Our computations reveal marked qualitative differences with the conventional transonic theory. Result of particular interest include the existence of multiple sonic points, significant decreases in the strength of compression shocks and critical mach numbers well in excess of 0.95 for NACA 0012 cross sections.

  8. 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.

  9. Flow of real gases through porous media 

    E-print Network

    Al-Hussainy, Rafi

    1965-01-01

    of state relating density with pressure. For real gases M (4) where M = molecular weight ~c. g. s or Darcy units will be used throughout this thesis. 10 R = gas constant T = absolute, temperature of gas, a constant z(p) = gas law deviation factor, a... potential, m(p), as follows: p h~) = [ph~) *(p) ] ~ dv p e(p) z(p) (15) m p where [p(p) z(p) is evaluated at p . The limits are set to give the pm m integral a definite value. Thus, the variable m(p) has the dimensions of pressure-squared. Since px...

  10. Toxicity of pyrolysis gases from wood

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Huttlinger, N. V.; Oneill, B. A.; Kourtides, D. A.; Parker, J. A.

    1977-01-01

    The toxicity of the pyrolysis gases from nine wood samples was investigated. The samples of hardwoods were aspen poplar, beech, yellow birch, and red oak. The samples of softwoods were western red cedar, Douglas fir, western hemlock, eastern white pine, and southern yellow pine. There was no significant difference between the wood samples under rising temperature conditions, which are intended to simulate a developing fire, or under fixed temperature conditions, which are intended to simulate a fully developed fire. This test method is used to determine whether a material is significantly more toxic than wood under the preflashover conditions of a developing fire.

  11. Method for detecting trace impurities in gases

    DOEpatents

    Freund, Samuel M. (Santa Fe, NM); Maier, II, William B. (Los Alamos, NM); Holland, Redus F. (Los Alamos, NM); Beattie, Willard H. (Los Alamos, NM)

    1981-01-01

    A technique for considerably improving the sensitivity and specificity of infrared spectrometry as applied to quantitative determination of trace impurities in various carrier or solvent gases is presented. A gas to be examined for impurities is liquefied and infrared absorption spectra of the liquid are obtained. Spectral simplification and number densities of impurities in the optical path are substantially higher than are obtainable in similar gas-phase analyses. Carbon dioxide impurity (.about.2 ppm) present in commercial Xe and ppm levels of Freon 12 and vinyl chloride added to liquefied air are used to illustrate the method.

  12. [Exposure to anesthetic gases: risk and prevention].

    PubMed

    Stoklov, M; Trouiller, P; Stieglitz, P; Lamalle, Y; Vincent, F; Perdrix, A; Marka, C; de Gaudemaris, R; Mallion, J M; Faure, J

    1983-09-01

    Several studies published during the last fifteen years seem to demonstrate that major risks, i.e. congenital malformations in the offspring and increased rate of spontaneous abortions, are associated with occupational exposure to anesthetic gases (halothane and nitrous oxide) in operating rooms. In view of the severity of the potential risk, we have: 1) analyzed risk factors in the light of epidermiologic and experimental studies; 2) determined the threshold levels of air pollution for these risk factors; 3) analyzed the situation in the Grenoble Hospital and the means of dealing with it. PMID:6312577

  13. Mean free path in soccer and gases

    NASA Astrophysics Data System (ADS)

    Luzuriaga, J.

    2010-09-01

    The trajectories of the molecules in an ideal gas and of the ball in a soccer game are compared. The great difference between these motions and some similarities are discussed. This example could be suitable for discussing many concepts in kinetic theory in a way that can be pictured by students for getting a more intuitive understanding. It could be suitable for an introductory course in vacuum techniques or undergraduate courses in kinetic theory of gases. Without going into the slightly harder quantitative results, the analysis presented might be used for introducing some ideas of kinetic theory qualitatively to high school students.

  14. Toxicity of pyrolysis gases from polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Schneider, J. E.

    1979-01-01

    A sample of polytetrafluoroethylene was evaluated for toxicity of pyrolysis gases, using various test conditions of the toxicity screening test method developed at the University of San Francisco. Time to death appears to be affected by the material of which the pyrolysis tube is made, with Monel tending to give longer times to death than quartz. When quartz tubes are used, time to death seems to be related to carbon monoxide concentration. When Monel tubes are used, carbon monoxide does not appear to be the principal toxicant.

  15. 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.

  16. 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.

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

    PubMed

    Dörr, Harald; Meineke, Viktor

    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

  18. 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

  19. 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.

  20. Importance of matrix correlations in dye-doped solid rare gases: A hole-burning study

    Microsoft Academic Search

    P. Geissinger; L. Kador; D. Haarer

    1996-01-01

    The present investigation was motivated by the apparent success of a statistical model to describe the effects of external pressure on spectral holes in dye-doped amorphous polymers. With its help, the polymer compressibility could be determined in a purely optical experiment. This success was surprising since polymers usually meet the basic assumptions of this model quite poorly. Furthermore, two conflicting

  1. Gases Inside the Earth / Muddy Waters

    NSDL National Science Digital Library

    This two-part radio broadcast first focuses on how scientists are re-evaluating their theories on how the Earth was formed, then on exploration for new life forms found in the sediments of ocean floors. By looking at volcanic hotspots, geologists can sample gases from deep inside the mantle of the Earth. These dissolved gases include particles from the solar wind and impacting asteroids. This broadcast discusses a new theory suggesting there were two distinct phases in the development of Earth and explains how Earth may have been hit by something as big as Mars, causing the formation of the Moon. There is discussion about how the two layers of the Earth mantle interact. In the second half of the broadcast, it is estimated there could be as many species below ground in deep-sea sediments as there are above water in our rainforests. There is discussion of the search for a family of bacteria called actinomycetes, which could be used to treat methicillin resistant Staphylococcus aureus (MRSA, an organism resistant to commonly used antibiotics); the range of species on the seafloor; and oil and gas companies' surveys to check what effect their activities are having on the ocean bottom. The broadcast is 29 minutes in length.

  2. Hydrodynamic collective modes for cold trapped gases

    NASA Astrophysics Data System (ADS)

    Boettcher, I.; Floerchinger, S.; Wetterich, C.

    2011-12-01

    We suggest that collective oscillation frequencies of cold trapped gases can be used to test predictions from quantum many-body physics. Our motivation lies in both rigid experimental tests of theoretical calculations and a possible improvement of measurements of particle number, chemical potential or temperature. We calculate the effects of interaction, dimensionality and thermal fluctuations on the collective modes of a dilute Bose gas in the hydrodynamic limit. The underlying equation of state is provided by the non-perturbative Functional Renormalization Group or by Lee-Yang theory. The spectrum of oscillation frequencies could be measured by response techniques. Our findings are generalized to bosonic or fermionic quantum gases with an arbitrary equation of state in the two-fluid hydrodynamic regime. For any given equation of state P(?, T) and normal fluid density nn(?, T), the collective oscillation frequencies in a d-dimensional isotropic potential are found to be the eigenvalues of an ordinary differential operator. We suggest a method of numerical solution and discuss the zero-temperature limit. Exact results are provided for harmonic traps and certain special forms of the equation of state. We also present a phenomenological treatment of dissipation effects and discuss the possibility of exciting the different eigenmodes individually.

  3. Quantum control and measurement of spins in laser cooled gases

    NASA Astrophysics Data System (ADS)

    Deutsch, Ivan

    2012-10-01

    Quantum information processing (QIP) requires three important ingredients: (i) preparing a desired initial quantum state, usually highly pure; (ii) controlling the dynamical evolution, usually via a desired unitary transformation; (iii) measuring the desired information encoded in the final quantum state. Many physical platforms are being developed for QIP, including trapped ions, semiconductor quantum dots, and atoms in optical lattices. In these cases, it is the spins of the system that encode the quantum information. Spins are natural carriers of quantum information given their long coherence times and our ability to control them with a variety of external electromagnetic fields. In addition, spins in laser-cooled atomic gases are an excellent testbed for exploring QIP protocols because of our ability to initially prepare highly pure states and employ the well-developed tools of quantum optics and coherent spectroscopy. In this talk I will give an overview of recent theory and experiment in the control and measurement of spins in laser-cooled atomic gases. We consider the hyperfine magnetic sublevels in the ground electronic states of ^133Cs, a 16-dimensional Hilbert space. We can explore all three ingredients described above: preparation of an arbitrary superposition state, evolution through an arbitrary unitary matrix, and readout through quantum state reconstruction of the full density matrix. We employ the tools of optimal quantum control and quantum estimation theory. The implementation involves atoms controlled by radio-frequency, microwave, a optical fields, and measured via polarization spectroscopy. The experiment is performed in the group of Prof. Poul S. Jessen, University of Arizona. This work was supported by the National Science Foundation.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Radiation disasters and children.

    PubMed

    2003-06-01

    The special medical needs of children make it essential that pediatricians be prepared for radiation disasters, including 1) the detonation of a nuclear weapon; 2) a nuclear power plant event that unleashes a radioactive cloud; and 3) the dispersal of radionuclides by conventional explosive or the crash of a transport vehicle. Any of these events could occur unintentionally or as an act of terrorism. Nuclear facilities (eg, power plants, fuel processing centers, and food irradiation facilities) are often located in highly populated areas, and as they age, the risk of mechanical failure increases. The short- and long-term consequences of a radiation disaster are significantly greater in children for several reasons. First, children have a disproportionately higher minute ventilation, leading to greater internal exposure to radioactive gases. Children have a significantly greater risk of developing cancer even when they are exposed to radiation in utero. Finally, children and the parents of young children are more likely than are adults to develop enduring psychologic injury after a radiation disaster. The pediatrician has a critical role in planning for radiation disasters. For example, potassium iodide is of proven value for thyroid protection but must be given before or soon after exposure to radioiodines, requiring its placement in homes, schools, and child care centers. Pediatricians should work with public health authorities to ensure that children receive full consideration in local planning for a radiation disaster. PMID:12777572

  9. 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

  10. Heat Transfer by Free Convection from Horizontal Cylinders in Diatomic Gases

    NASA Technical Reports Server (NTRS)

    Hermann, R

    1954-01-01

    The case of the horizontal cylinder is of particular importance in the study of heat transfer by free convection for the following reasons: In the first place, next to the rectangular plate it represents the simplest two-dimensional case; and second, a very wide range of measurements is possible, from the finest electrically heated glow lamp wires to pipes heated by liquids or gases flowing through them.

  11. Char yield and flash-fire propensity of pyrolysis gases from materials

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Brandt, D. L.

    1978-01-01

    Comparison of the char yield after occurrence of a flash fire in the pyrolysis gases from various materials indicates that increased char yield appears to be associated with reduced flash-fire propensity for certain types of materials. For certain other materials, flash-fire propensity appears to be independent of char yield. The mechanisms of thermal decomposition and char formation may be more important factors in flash-fire propensity than the quantitative degree of char formation.

  12. Spectrum of two-photon absorption coefficient for GaSe

    Microsoft Academic Search

    I. B. Zotova; Y. J. Ding

    2001-01-01

    Summary form only given. The spectrum of the two-photon absorption (TPA) coefficient is crucial for its applications in optical power limiting, autocorrelation, two-photon luminescence, and is important for optical parametric oscillation. GaSe has a large value of second-order nonlinear coefficient and a wide transparency range (0.62-20 ?m) ideal for the efficient generation of mid- and far-IR. The value of the

  13. Spectral line-based weighted-sum-of-gray-gases model in nonisothermal nonhomogeneous media

    SciTech Connect

    Denison, M.K.; Webb, B.W. [Brigham Young Univ., Provo, UT (United States)

    1995-05-01

    An approach is developed to extend the previously developed spectral-line weighted-sum-of-gray-gases (SLW) model to nonisothermal, nonhomogeneous media. The distinguishing feature of the SLW gas property model is that it has been developed for use in arbitrary solution methods of the radiative transfer equation (RTE). A spatial dependence of the gray gas absorption cross sections on local temperature, pressure, and mole fraction is introduced through the absorption-line blackbody distribution function. Incorporating this spatial dependence results in significant improvement over the use of spatially uniform gray gas absorption cross sections in comparisons with line-by-line benchmarks. 16 refs., 7 figs.

  14. Coupled Soot and Radiation Calculations in a Compartment Fire

    Microsoft Academic Search

    J. B. Moss; P. A. Rubini

    A strategy is described in which an extended flamelet approach to soot modelling is linked to the discrete transfer radiation model, incorporating a weighted sum of grey gases solution to the radiative transfer equation. The simplification to chemical source term representation during turbulent burning, which is introduced by laminar flamelet modelling, is applied to a reduced description of soot formation.

  15. 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.

  16. Gas leak through ultrathin radiation entrance windows

    Microsoft Academic Search

    Veli-Pekka Viitanen; Heini Harvela

    1995-01-01

    The permeation rates through an ultrathin radiation entrance window membrane have been measured for several common detector gas components, as well as for some atmospheric gases, by collecting the permeated gas into a clean volume equipped with an absolute pressure transducer. The dependence of the leak rate on the differential pressure (1.0 bar in most of the measurements) has also

  17. Industrial gases offer new processing alternatives

    SciTech Connect

    Jackow, F.

    1996-07-01

    Creative use of industrial gases, such as oxygen, nitrogen, hydrogen and carbon dioxide, can provide new approaches to many chemical and industrial processes. One example is using pure oxygen to replace air for combustion, a technique that makes it possible to increase incineration efficiency and reduce the amount of nitrogen oxides produced, thus lowering a plant`s environmental impact. Recent downsizing trends, cost-reduction efforts and environmental regulations have modified the relationship between major chemical and industrial gas companies. Chemical producers are now often interested in outsourcing not only industrial gas supply but also technology and turnkey solutions. Among the benefits to the end users are enhanced safety, reduced environmental impact and improved profitability.

  18. Universality classes of driven lattice gases

    PubMed

    Garrido; Munoz; de los Santos F

    2000-05-01

    Motivated by some recent criticisms to our alternative Langevin equation for driven lattice gases (DLG) under an infinitely large driving field, we revisit the derivation of such an equation, and test its validity. As a result, an additional term, coming from a careful consideration of entropic contributions, is added to the equation. This term heals all the recently reported generic infrared singularities. The emerging equation is then identical to that describing randomly driven diffusive systems. This fact confirms our claim that the infinite driving limit is singular, and that the main relevant ingredient determining the critical behavior of the DLG in this limit is the anisotropy and not the presence of a current. Different aspects of our picture are discussed, and it is concluded that it constitutes a very plausible scenario to rationalize the critical behavior of the DLG and variants of it. PMID:11031501

  19. 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.

  20. Concomitant modulated superfluidity in polarized Fermi gases

    SciTech Connect

    Baksmaty, L. O.; Lu Hong; Pu Han [Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, Texas 77005 (United States); Bolech, C. J. [Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221 (United States); Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, Texas 77005 (United States)

    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. Biomedical imaging with hyperpolarized noble gases

    NASA Astrophysics Data System (ADS)

    Ruppert, Kai

    2014-11-01

    Hyperpolarized noble gases (HNGs), polarized to approximately 50% or higher, have led to major advances in magnetic resonance (MR) imaging of porous structures and air-filled cavities in human subjects, particularly the lung. By boosting the available signal to a level about 100?000 times higher than that at thermal equilibrium, air spaces that would otherwise appear as signal voids in an MR image can be revealed for structural and functional assessments. This review discusses how HNG MR imaging differs from conventional proton MR imaging, how MR pulse sequence design is affected and how the properties of gas imaging can be exploited to obtain hitherto inaccessible information in humans and animals. Current and possible future imaging techniques, and their application in the assessment of normal lung function as well as certain lung diseases, are described.

  2. Inerting Aircraft Fuel Systems Using Exhaust Gases

    NASA Technical Reports Server (NTRS)

    Hehemann, David G.

    2002-01-01

    Our purpose in this proposal was to determine the feasibility of using carbon dioxide, possibly obtained from aircraft exhaust gases as a substance to inert the fuel contained in fuel tanks aboard aircraft. To do this, we decided to look at the effects carbon dioxide has upon commercial Jet-A aircraft fuel. In particular, we looked at the solubility of CO2 in Jet-A fuel, the pumpability of CO2-saturated Jet-A fuel, the flashpoint of Jet-A fuel under various mixtures of air and CO2, the static outgassing of CO2-Saturated Jet-A fuel and the dynamic outgassing of Jet-A fuel during pumping of Jet-A fuel.

  3. 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

  4. Sir William Ramsay and the noble gases.

    PubMed

    Davies, Alwyn G

    2012-01-01

    Sir William Ramsay was one of the world's leading scientists at the end of the 19th century, and in a spectacular period of research between 1894 and 1898, he discovered five new elements. These were the noble gases, helium, neon, argon, krypton, and xenon; they added a whole new group to the Periodic Table of the elements, and provided the keystone to our understanding of the electronic structure of atoms, and the way those electrons bind the atoms together into molecules. For this work he was awarded the Nobel Prize in Chemistry in 1904, the first such prize to come to a British subject. He was also a man of great charm, a good linguist, and a composer and performer of music, poetry and song. This review will trace his career, describe his character and give and account of the chemistry which led to the award of the Nobel Prize. PMID:22574384

  5. Advanced Global Atmospheric Gases Experiment (AGAGE)

    NASA Technical Reports Server (NTRS)

    Weiss, R. F.

    1998-01-01

    The Advanced Global Atmospheric Gases Experiment (AGAGE) is an ongoing research project, for which the work carried out by the Scripps Institution of Oceanography. Due to the need to complete AGAGE activities specifically funded under NAGW-2034 that had been delayed, a no-cost extension to this grant was obtained, creating an overlap period between the two grants. Because the AGAGE project is continuing, and a Final Project Report is required only because of the change in grant numbers, it is most appropriate to submit for this report the Introduction and Accomplishments sections which appear on pages 1-62 of the October 1998 AGAGE renewal proposal. A copy of the complete proposal is attached.

  6. Remote sensing of turbine engine gases

    NASA Astrophysics Data System (ADS)

    Killinger, D. K.; Menyuk, N.; Mooradian, A.

    1980-09-01

    This is the FY 80 final report for a laser remote sensing program designed to investigate remote sensing techniques for the detection of jet aircraft exhaust gases. The specific tasks which were performed consisted of the following: (1) continuation of feasibility demonstration of CO2 TEA laser remote sensing system and the detection of NO and C2H4 in the atmosphere; (2) continuation of laboratory absorption measurements of CO, NO, and C2H4; (3) initial laboratory investigation of suitability of laser remote s U;e, Unsing of hydrazine, UDMH, and MMH; (4) implemenation of digital data acquisition and processing system; and (5) preliminary development of dual-laser DIAL system.

  7. 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.

  8. Spectroscopic Temperature Determination of Degenerate Fermi Gases

    E-print Network

    Marijan Koštrun; Robin Côté

    2003-09-22

    We suggest a simple method for measuring the temperature of ultra-cold gases made of fermions. We show that by using a two-photon Raman probe, it is possible to obtain lineshapes which reveal properties of the degenerate sample, notably its temperature $T$. The proposed method could be used with identical fermions in different hyperfine states interacting via s-wave scattering or identical fermions in the same hyperfine state via p-wave scattering. We illustrate the applicability of the method in realistic conditions for $^6$Li prepared in two different hyperfine states. We find that temperatures down to 0.05 $T_{F}$ can be determined by this {\\it in-situ} method.

  9. 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.

  10. 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

  11. 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.

  12. 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

  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. 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.

  15. 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.

  16. ANALYSIS OF COMMERCIAL NO PROTOCOL GASES (A QA ASSESSMENT)

    EPA Science Inventory

    EPA has initiated a national QA program on the suppliers of Protocol Gases. n this program, which will operate continuously, Protocol Gases are obtained and analyzed by EPA. he results of this EPA analysis are then compared to the Certificate of Analysis supplied with the Protoco...

  17. Assessment report on NRP subtheme “gGeenhouse Gases”

    Microsoft Academic Search

    J. G. de Beer

    1995-01-01

    The aim of the subtheme Greenhouse gases of the Dutch National Research programme on (NRP) is to quantify the sources and sinks of the major greenhouse gases to enable estimates of the future atmospheric concentration. The major part of the projects in this theme is focused on the Dutch situation, but the results can be extrapolated countries or regions. The

  18. Climate change and trace gases BY JAMES HANSEN

    E-print Network

    Ford, Andrew

    Climate change and trace gases BY JAMES HANSEN 1,*, MAKIKO SATO 1 , PUSHKER KHARECHA 1 , GARY climate change that could run out of our control, with great dangers for humans and other creatures and the global environment. Keywords: climate change; trace gases; climate feedbacks; black carbon; sea level

  19. AMIII Termodinamica dos Gases Ideais 17 de Janeiro de 2002

    E-print Network

    Natário, José

    AMIII ­ Termodinâ??amica dos Gases Ideais 17 de Janeiro de 2002 N moles de um gâ??as ideal em equil dos gases ideais). A Primeira Lei da Termodinâ??amica afirma que existe uma funâ?ºcâ?ao E : M # R, dita pela Segunda Lei da Termodinâ??amica. 2 #12;

  20. 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…

  1. Solubility of non-polar gases in electrolyte solutions

    NASA Technical Reports Server (NTRS)

    Walker, R. L., Jr.

    1970-01-01

    Solubility theory describes the effects of both concentration and temperature on solute activity coefficients. It predicts the salting-out effect and the decrease in solubility of non-polar gases with increased electrolyte concentration, and can be used to calculate heats of solution, entropies, and partial molal volumes of dissolved gases

  2. 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…

  3. Low-drag airfoils for transonic flow of dense gases

    Microsoft Academic Search

    Zvi Rusak; Chun-Wei Wang

    2000-01-01

    Low-drag airfoils for transonic flow of BZT gases are constructed through a nonlinear small-disturbance theory on this topic. This kind of transonic flow is characterized by the high nonlinearity of the fluid thermodynamic behavior that is closely coupled with its compressible flow dynamics. Utilizing BZT gases may result in low drag exerted on airfoils operating at high transonic speeds. This

  4. Novel MRI Applications of Laser-Polarized Noble Gases

    Microsoft Academic Search

    R. W. Mair; R. L. Walsworth

    2002-01-01

    Gas-phase NMR has great potential as a probe for a variety of interesting physical and biomedical problems that are not amenable to study by water or similar liquid. However, NMR of gases was largely neglected due to the low signal obtained from the thermally-polarized gases with very low sample density. The advent of optical pumping techniques for enhancing the polarization

  5. DUALITY SOLUTIONS FOR PRESSURELESS GASES, MONOTONE SCALAR CONSERVATION LAWS,

    E-print Network

    d'Orléans, Université

    DUALITY SOLUTIONS FOR PRESSURELESS GASES, MONOTONE SCALAR CONSERVATION LAWS, AND UNIQUENESS Fran pressureless gases, the dynamics of sticky par­ ticles and nonlinear scalar conservation laws with monotone -- scalar conservation laws -- Hamilton­Jacobi equations -- entropy conditions Work partially supported

  6. 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...

  7. Towards a fully kinetic 3D electromagnetic particle-in-cell model of streamer formation and dynamics in high-pressure electronegative gases

    SciTech Connect

    Rose, D. V.; Welch, D. R.; Clark, R. E.; Thoma, C.; Zimmerman, W. R.; Bruner, N. [Voss Scientific, LLC, Albuquerque, New Mexico 87108 (United States); Rambo, P. K.; Atherton, B. W. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2011-09-15

    Streamer and leader formation in high pressure devices is dynamic process involving a broad range of physical phenomena. These include elastic and inelastic particle collisions in the gas, radiation generation, transport and absorption, and electrode interactions. Accurate modeling of these physical processes is essential for a number of applications, including high-current, laser-triggered gas switches. Towards this end, we present a new 3D implicit particle-in-cell simulation model of gas breakdown leading to streamer formation in electronegative gases. The model uses a Monte Carlo treatment for all particle interactions and includes discrete photon generation, transport, and absorption for ultra-violet and soft x-ray radiation. Central to the realization of this fully kinetic particle treatment is an algorithm that manages the total particle count by species while preserving the local momentum distribution functions and conserving charge [D. R. Welch, T. C. Genoni, R. E. Clark, and D. V. Rose, J. Comput. Phys. 227, 143 (2007)]. The simulation model is fully electromagnetic, making it capable of following, for example, the evolution of a gas switch from the point of laser-induced localized breakdown of the gas between electrodes through the successive stages of streamer propagation, initial electrode current connection, and high-current conduction channel evolution, where self-magnetic field effects are likely to be important. We describe the model details and underlying assumptions used and present sample results from 3D simulations of streamer formation and propagation in SF{sub 6}.

  8. 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

    Microsoft Academic Search

    M. Z. Jacobson

    2005-01-01

    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

  9. 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.

  10. Far-UV Radiation of the Early Sun

    NASA Technical Reports Server (NTRS)

    Heap, Sally

    2005-01-01

    Far-UV radiation is responsible for the photolysis of important greenhouse gases such as CO2, NH3 (ammonia), CH4 (methane) and more generally, the global UV photochemistry of the early atmosphere. In our project, we are concentrating on the young Sun's effect on methane, since UV sunlight (lambda less than 1450 Angstroms) was the main destruction mechanism for methane in the early Earth's atmosphere. Since the UV luminosity of the early Sun cannot be calculated a priori; it can only be estimated from observations of stars similar to the young Sun. We report our results based on Hubble + FUSE spectra of stars selected from Gaidos (1998) Catalog of Nearby Young Solar Analogs (YSA's).

  11. Synthesis and growth of GaSe single crystals

    NASA Astrophysics Data System (ADS)

    Zhu, Chongqiang; Lei, Zuotao; Song, Liangcheng; Ma, Tianhui; Yang, Chunhui

    2015-07-01

    One-temperature and two-temperature synthesis methods for GaSe, a nonlinear optical compound, were developed. X-ray diffraction showed that pure ?-GaSe was synthesized. By Vertical Bridgman method using spontaneous nucleation the GaSe single crystals were grown with diameter 20-25 mm and length 40-45 mm and yield ~60%. The rocking curve for the studied GaSe sample was symmetric and its FWHM did not exceed 3?, which corresponds to the dislocation density at the level of 1012-1013 cm-2. SEM showed imperfections of surface of non-etched cleaved GaSe. According the obtained data the absorption coefficient at 1.06 ?m and 2 ?m is ~0.1 cm-1. At 9.3-10.9 ?m for nonpolarized light the calculations give absorption coefficient ~0.1-0.12 cm-1.

  12. Modified GaSe crystals for mid-IR applications

    NASA Astrophysics Data System (ADS)

    Singh, N. B.; Suhre, D. R.; Rosch, W.; Meyer, R.; Marable, M.; Fernelius, N. C.; Hopkins, F. K.; Zelmon, D. E.; Narayanan, R.

    1999-03-01

    We have synthesized stoichiometric batches of GaSe by reacting mixtures of the parent components and have grown centimeter-size modified single crystals of GaSe by the vertical Bridgman technique. GaSe crystals doped with silver, indium and silver gallium selenide were fabricated for wavelength conversion. Silver doping produced scattering centers which could be dissolved by annealing at temperatures above 700°C. Crystals cracked extensively during the annealing process and optical quality deteriorated. SHG measurements of In-doped crystals showed a " d" value of 49 pm/V for low concentration In-doped GaSe crystals. The silver gallium selenide doped GaSe crystals showed a " d" value of 75 pm/V which resulted in significant increase in the " d2/ n3".

  13. CONDENSATION/ADSORPTION AND EVACUATION OF RESIDUAL GASES IN THE SRF SYSTEM FOR THE CESR LUMINOSITY UPGRADE

    E-print Network

    Geng, Rong-Li

    to simulate the gas conden- sation/adsorption profile along the waveguide. The warm- up desorption curveCONDENSATION/ADSORPTION AND EVACUATION OF RESIDUAL GASES IN THE SRF SYSTEM FOR THE CESR LUMINOSITY coupler performance in a superconducting RF system. It is there- fore important to understand condensation/adsorption

  14. 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.

  15. Radiative Forcing - Measured at Earth's Surface - Corroborate the Increasing Greenhouse Effect

    Microsoft Academic Search

    Rolf Philipona; B. Duerr; Christoph Marty; Atsumu Ohmura; Martin Wild

    2004-01-01

    The Intergovernmental Panel of Climate Change (IPCC) confirmed concentrations of atmospheric greenhouse gases and radiative forcing to increase as a result of human activities. Nevertheless, changes in radiative forcing related to increasing greenhouse gas concentrations could not be detected with instrumental measurements at Earth's surface so far. Here we show that atmospheric longwave downward radiation significantly increased (+5.2 Wm-2) partly

  16. 40 CFR 71.13 - Enforceable commitments for further actions addressing Greenhouse Gases (GHGs)

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...commitments for further actions addressing Greenhouse Gases (GHGs) 71.13 Section 71...commitments for further actions addressing Greenhouse Gases (GHGs) (a) Definitions —(1) Greenhouse Gases (GHGs) means the air...

  17. 40 CFR 52.22 - Enforceable commitments for further actions addressing the pollutant greenhouse gases (GHGs).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...further actions addressing the pollutant greenhouse gases (GHGs). 52.22 Section...further actions addressing the pollutant greenhouse gases (GHGs). (a) Definitions. (1) Greenhouse Gases (GHGs) means the air...

  18. 40 CFR 71.13 - Enforceable commitments for further actions addressing Greenhouse Gases (GHGs)

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...commitments for further actions addressing Greenhouse Gases (GHGs) 71.13 Section 71...commitments for further actions addressing Greenhouse Gases (GHGs) (a) Definitions —(1) Greenhouse Gases (GHGs) means the air...

  19. 40 CFR 52.22 - Enforceable commitments for further actions addressing the pollutant greenhouse gases (GHGs).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...further actions addressing the pollutant greenhouse gases (GHGs). 52.22 Section...further actions addressing the pollutant greenhouse gases (GHGs). (a) Definitions. (1) Greenhouse Gases (GHGs) means the air...

  20. 40 CFR 70.12 - Enforceable commitments for further actions addressing greenhouse gases (GHGs).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...commitments for further actions addressing greenhouse gases (GHGs). 70.12 Section...commitments for further actions addressing greenhouse gases (GHGs). (a) Definitions. (1) Greenhouse Gases (GHGs) means the air...

  1. 40 CFR 71.13 - Enforceable commitments for further actions addressing greenhouse gases (GHGs).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...commitments for further actions addressing greenhouse gases (GHGs). 71.13 Section...commitments for further actions addressing greenhouse gases (GHGs). (a) Definitions —(1) Greenhouse Gases (GHGs) means the air...

  2. 40 CFR 70.12 - Enforceable commitments for further actions addressing greenhouse gases (GHGs).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...commitments for further actions addressing greenhouse gases (GHGs). 70.12 Section...commitments for further actions addressing greenhouse gases (GHGs). (a) Definitions. (1) Greenhouse Gases (GHGs) means the air...

  3. 40 CFR 70.12 - Enforceable commitments for further actions addressing greenhouse gases (GHGs).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...commitments for further actions addressing greenhouse gases (GHGs). 70.12 Section...commitments for further actions addressing greenhouse gases (GHGs). (a) Definitions. (1) Greenhouse Gases (GHGs) means the air...

  4. 40 CFR 52.22 - Enforceable commitments for further actions addressing the pollutant greenhouse gases (GHGs).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...further actions addressing the pollutant greenhouse gases (GHGs). 52.22 Section...further actions addressing the pollutant greenhouse gases (GHGs). (a) Definitions. (1) Greenhouse Gases (GHGs) means the air...

  5. 40 CFR 71.13 - Enforceable commitments for further actions addressing greenhouse gases (GHGs).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...commitments for further actions addressing greenhouse gases (GHGs). 71.13 Section...commitments for further actions addressing greenhouse gases (GHGs). (a) Definitions —(1) Greenhouse Gases (GHGs) means the air...

  6. 40 CFR 52.22 - Enforceable commitments for further actions addressing the pollutant greenhouse gases (GHGs).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...further actions addressing the pollutant greenhouse gases (GHGs). 52.22 Section...further actions addressing the pollutant greenhouse gases (GHGs). (a) Definitions. (1) Greenhouse Gases (GHGs) means the air...

  7. 40 CFR 70.12 - Enforceable commitments for further actions addressing greenhouse gases (GHGs).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...commitments for further actions addressing greenhouse gases (GHGs). 70.12 Section...commitments for further actions addressing greenhouse gases (GHGs). (a) Definitions. (1) Greenhouse Gases (GHGs) means the air...

  8. Decoherence mechanisms of Landau level THz excitations in two dimensional electron gases

    SciTech Connect

    Maissen, Curdin; Scalari, Giacomo; Faist, Jérôme [Institut für Quantenelektronik, ETH Zürich (Switzerland); Reichl, Christian; Wegscheider, Werner [Laboratorium für Festkörperphysik, ETH Zürich (Switzerland)

    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.

  9. 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

  10. Methane activation using noble gases in a dielectric barrier discharge reactor

    SciTech Connect

    Jo, Sungkwon; Hoon Lee, Dae; Seok Kang, Woo; Song, Young-Hoon [Korea Institute of Machinery and Materials, 156 Gajeongbuk-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)] [Korea Institute of Machinery and Materials, 156 Gajeongbuk-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)

    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.

  11. 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.

  12. A comprehensive study of different gases in inductively coupled plasma torch operating at one atmosphere

    SciTech Connect

    Punjabi, Sangeeta B. [Electrical Engineering Department, V. J.T.I, Matunga, Mumbai 400019 (India); Department of Physics, University of Mumbai, Kalina, Santacruz (E) 400098 (India); Joshi, N. K. [Faculty of Engineering and technology, MITS, lakshmangarh, (Sikar), Rajasthan 332311 (India); Mangalvedekar, H. A.; Lande, B. K. [Electrical Engineering Department, V. J.T.I, Matunga, Mumbai 400019 (India); Das, A. K. [Laser and Plasma Technology Division, BARC, Mumbai 400085 (India); Kothari, D. C. [Department of Physics, University of Mumbai, Kalina, Santacruz(E) 400098 (India)

    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.

  13. [Radiation protection in radiation oncology. Yesterday, today, and tomorrow].

    PubMed

    Herrmann, Th; Müller, R

    2012-11-01

    Publications about radiation protection issues are not very frequent in the 100-year-old history of Strahlentherapie und Onkologie. While at the beginning of the last century the problems of radiation protection were determined by the technical development of radiation therapy, the importance of radiation protection measures and knowledge about radiation protection by the persons involved has clearly increased. A new challenge is treating patients according to radiation safety issues to avoid the risk of stochastic late effects, such as radiation-induced secondary tumors. PMID:22907582

  14. Characterisation of the interaction of 40fs, 10J laser pulses with gases of atomic clusters

    NASA Astrophysics Data System (ADS)

    Symes, Daniel; Olsson-Robbie, Stefan; Doyle, Hugo; Lowe, Hazel; Price, Chris; Bigourd, Damien; Patankar, Siddharth; Mecseki, Katalin; Booth, Nicola; Scott, Robbie; Moore, Alastair; Hohenberger, Matthias; Rodriguez, Rafael; Gumbrell, Edward; Smith, Roland

    2012-10-01

    The interaction of short, intense laser pulses with clustered gas is distinct from that with monatomic gases since the high density in the cluster enables efficient energy deposition. The dramatic heating of the clusters transfers a large portion of the laser energy into ions and, with deuterated gases, can provide a pulsed neutron source. After the laser pulse, hot plasma remains that provides a debris-free EUV and K-alpha x-ray source. The subsequent explosion launches radiative shock waves that are suitable for laboratory astrophysics experiments. Our experiment uses the Astra-Gemini laser with energies above 10J, whereas most studies have been limited to of order 1J. We will characterise blast waves through optical imaging and time-resolved x-ray measurements to determine thresholds for radiative instabilities. We will also study secondary source generation by measuring x-ray, electron and ion yields. In particular we will investigate wakefield acceleration and the associated betatron hard x-ray emission and present a direct comparison with a helium gas experiment to determine the influence of clusters.

  15. On surface temperature, greenhouse gases, and aerosols: models and observations

    SciTech Connect

    Mitchell, J.F.B.; Davis, R.A.; Ingram, W.J.; Senior, C.A. [Hadley Centre for Climate Prediction and Research, Berkshire (United Kingdom)] [Hadley Centre for Climate Prediction and Research, Berkshire (United Kingdom)

    1995-10-01

    The effect of changes in atmospheric carbon dioxide concentrations and sulphate aerosols on near-surface temperature is investigated using a version of the Hadley Centre atmospheric model coupled to a mixed layer ocean. The scattering of sunlight by sulphate aerosols is represented by appropriately enhancing the surface albedo. On doubling atmospheric carbon dioxide concentrations, the global mean temperature increases by 5.2 K. An integration with a 39% increase in CO{sub 2}, giving the estimated change in radiative heating due to increases in greenhouse gases since 1900, produced an equilibrium warming of 2.3 K, which, even allowing for oceanic inertia, is significantly higher than the observed warming over the same period. Furthermore, the simulation suggests a substantial warming everywhere, whereas the observations indicate isolated regions of cooling, including parts of the northern midlatitude continents. The addition of an estimate of the effect of scattering by current industrial aerosols (uncertain by a factor of at least 3) leads to improved agreement with the observed pattern of changes over the northern continents and reduces the global mean warming by about 30%. Doubling the aerosol forcing produces patterns that are still compatible with the observations, but further increase leads to unrealistically extensive cooling in the midlatitudes. The diurnal range of surface temperature decreases over most of the northern extratropics on increasing CO{sub 2}, in agreement with recent observations. The addition of the current industrial aerosol had little detectable effect on the diurnal range in the model because the direct effect of reduced solar heating at the surface is approximately balanced by the indirect effects of cooling. Thus, the ratio of the reduction in diurnal range to the mean warming is increased, in closer agreement with observations. Results from further sensitivity experiments with larger increases in aerosol and CO{sub 2} are presented.

  16. Rayleigh scattering measurements of several fluorocarbon gases.

    PubMed

    Zadoo, Serena; Thompson, Jonathan E

    2011-11-01

    Integrating nephelometers are commonly used to monitor airborne particulate matter. However, they must be calibrated prior to use. The Rayleigh scattering coefficients (b(RS), Mm(-1)), scattering cross sections (?(RS), cm(2)), and Rayleigh multipliers for tetrafluoromethane (R-14), sulfur hexafluoride, pentafluoroethane (HFC-125), hexafluoropropene (HFC-216), 1,1,1,2,3,3,3,-heptafluoropropane (HFC-227ea), and octafluorocyclobutane (C-318) are reported from measurements made using a Radiance Research M903 integrating nephelometer operating at ? = 530 nm and calibration with gases of known scattering constants. Rayleigh multipliers (±90% conf. int.) were found to be 2.6 ± 0.5, 6.60 ± 0.07, 7.5 ± 1, 14.8 ± 0.9, 15.6 ± 0.5, and 22.3 ± 0.8 times that of air, respectively. To the best of our knowledge, these are the first reported values for R-14, HFC-216, HFC-125, and C-318. Experimental accuracy is supported through measurements of values for SF(6) and HFC-227ea which agree to within 3% of previous literature reports. In addition to documenting fundamental Rayleigh scattering data for the first time, the information presented within will find use for calibration of optical scattering sensors such as integrating nephelometers. PMID:22027960

  17. Measuring non-condensable gases in steam.

    PubMed

    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 3M(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. PMID:24289436

  18. Universal nonequilibrium properties of dissipative Rydberg gases.

    PubMed

    Marcuzzi, Matteo; Levi, Emanuele; Diehl, Sebastian; Garrahan, Juan P; Lesanovsky, Igor

    2014-11-21

    We investigate the out-of-equilibrium behavior of a dissipative gas of Rydberg atoms that features a dynamical transition between two stationary states characterized by different excitation densities. We determine the structure and properties of the phase diagram and identify the universality class of the transition, both for the statics and the dynamics. We show that the proper dynamical order parameter is in fact not the excitation density and find evidence that the dynamical transition is in the "model A" universality class; i.e., it features a nontrivial Z2 symmetry and a dynamics with nonconserved order parameter. This sheds light on some relevant and observable aspects of dynamical transitions in Rydberg gases. In particular it permits a quantitative understanding of a recent experiment [C. Carr, Phys. Rev. Lett. 111, 113901 (2013)] which observed bistable behavior as well as power-law scaling of the relaxation time. The latter emerges not due to critical slowing down in the vicinity of a second order transition, but from the nonequilibrium dynamics near a so-called spinodal line. PMID:25479477

  19. The NRxx Method for Polyatomic Gases

    E-print Network

    Zhenning Cai; Ruo Li

    2012-02-16

    In this paper, we propose a numerical regularized moment method to solve the Boltzmann equation with ES-BGK collision term to simulate polyatomic gas flows. This method is an extension to the polyatomic case of the method proposed in [9], which is abbreviated as the NRxx method in [8]. Based on the form of the Maxwellian, the Laguerre polynomials of the internal energy parameter are used in the series expansion of the distribution function. We develop for polyatomic gases all the essential techniques needed in the NRxx method, including the efficient projection algorithm used in the numerical flux calculation, the regularization based on the Maxwellian iteration and the order of magnitude method, and the linearization of the regularization term for convenient numerical implementation. Meanwhile, the particular integrator in time for the ES-BGK collision term is put forward. The shock tube simulations with Knudsen numbers from 0.05 up to 5 are presented to demonstrate the validity of our method. Moreover, the nitrogen shock structure problem is included in our numerical experiments for Mach numbers from 1.53 to 6.1.

  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. From cavity QED with quantum gases to optomechanics

    SciTech Connect

    Ritsch, Helmut [University of Innsbruck, Innsbruck (Austria)

    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.

  2. Gases as uremic toxins: is there something in the air?

    PubMed

    Jankowski, Joachim; Westhof, Timm; Vaziri, Nosratola D; Ingrosso, Diego; Perna, Alessandra F

    2014-03-01

    The field of uremic toxicity comprises the study of a large number of different substances, classified in relation to various characteristics, for example, protein-binding, dimensions, and so forth. The endogenous compounds of a gaseous nature have received much attention lately from the scientific community because of their increasingly recognized importance in health and disease. Among these substances, some are uremic toxins per se, others are related to uremic toxins, or can become toxic under some circumstances. We divided them into two broad categories: organic and inorganic compounds. Among the organic compounds are phenols, indols, 2-methoxyresorcinol, p-hydroxy hippuric acid and phenyl acetic acid, trimethylamine, and dimethylamine; among the inorganic solutes are ammonia, nitric oxide, carbon monoxide, and hydrogen sulfide. In this article, these substances are described in relation to the elements that they affect or by which they are affected in uremia, which are the blood, breath, stools, and the gastrointestinal tract. In addition, the effect of the dialysis procedure on exhaled gases are described. PMID:24780469

  3. Extreme sensitivity of graphene photoconductivity to environmental gases

    PubMed Central

    Docherty, Callum J.; Lin, Cheng-Te; Joyce, Hannah J.; Nicholas, Robin J.; Herz, Laura M.; Li, Lain-Jong; Johnston, Michael B.

    2012-01-01

    Graphene is a single layer of covalently bonded carbon atoms, which was discovered only 8 years ago and yet has already attracted intense research and commercial interest. Initial research focused on its remarkable electronic properties, such as the observation of massless Dirac fermions and the half-integer quantum Hall effect. Now graphene is finding application in touch-screen displays, as channels in high-frequency transistors and in graphene-based integrated circuits. The potential for using the unique properties of graphene in terahertz-frequency electronics is particularly exciting; however, initial experiments probing the terahertz-frequency response of graphene are only just emerging. Here we show that the photoconductivity of graphene at terahertz frequencies is dramatically altered by the adsorption of atmospheric gases, such as nitrogen and oxygen. Furthermore, we observe the signature of terahertz stimulated emission from gas-adsorbed graphene. Our findings highlight the importance of environmental conditions on the design and fabrication of high-speed, graphene-based devices. PMID:23187628

  4. The stability of compressible mixing layers in binary gases

    NASA Technical Reports Server (NTRS)

    Kozusko, F.; Lasseigne, D. G.; Grosch, C. E.; Jackson, T. L.

    1996-01-01

    We present the results of a study of the inviscid two-dimensional spatial stability of a parallel compressible mixing layer in a binary gas. The parameters of this study are the Mach number of the fast stream, the ratio of the velocity of the slow stream to that of the fast stream, the ratio of the temperatures, the composition of the gas in the slow stream and in the fast stream, and the frequency of the disturbance wave. The ratio of the molecular weight of the slow stream to that of the fast stream is found to be an important quantity and is used as an independent variable in presenting the stability characteristics of the flow. It is shown that differing molecular weights have a significant effect on the neutral-mode phase speeds, the phase speeds of the unstable modes, the maximum growth rates and the unstable frequency range of the disturbances. The molecular weight ratio is a reasonable predictor of the stability trends. We have further demonstrated that the normalized growth rate as a function of the convective Mach number is relatively insensitive (Approx. 25%) to changes in the composition of the mixing layer. Thus, the normalized growth rate is a key element when considering the stability of compressible mixing layers, since once the basic stability characteristics for a particular combination of gases is known at zero Mach number, the decrease in growth rates due to compressibility effects at the larger convective Mach numbers is somewhat predictable.

  5. Titanium-sponge bed to scavenge tritium from inert gases

    NASA Astrophysics Data System (ADS)

    Nishikawa, Masabumi; Kido, Hidetoshi; Kotoh, Kenji; Sugisaki, Masayasu

    1983-03-01

    Chemical getters can be used to scavenge hydrogen isotopes from inert gases in HTGRs or fusion reactors. It is necessary that getter materials have a large gas-solid mass transfer capacity coefficient for scavenging hydrogen isotopes from inert gases. Absorption and desorption characteristics of hydrogen isotopes in a titanium sponge bed is examined in this study. Discussions are mainly based on data obtained from breakthrough curves. Experimental results show that the titanium-sponge bed is a good candidate material for scavenging and fixation of tritium from inert gases.

  6. 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

  7. Analysis of well gases from areas of geothermal power potential

    NASA Astrophysics Data System (ADS)

    Ludwick, J. D.; Robertson, D. E.; Fruchter, J. S.; Wilkerson, C. L.

    Geothermal fluids from the hydrothermal area of the Imperial Valley, California and the geopressured zone of Louisiana were found to contain a variety of noncondensable gases. Each geothermal reservoir has a predominant species, carbon dioxide in the former and methane in the latter. This paper describes the sampling techniques and reports the results of quantitative analysis of the gases that can be anticipated to affect the air quality in future energy production from this rapidly developing resource. In some instances the desirable qualities of these gases could contribute to the economic development of geothermal power.

  8. Process for scavenging hydrogen sulfide from hydrocarbon gases

    SciTech Connect

    Fox, I.

    1981-01-20

    A process for scavenging hydrogen sulfide from hydrocarbon gases utilizes iron oxide particles of unique chemical and physical properties. These particles have large surface area, and are comprised substantially of amorphous Fe/sub 2/O/sub 3/ containing a crystalline phase of Fe/sub 2/O/sub 3/, Fe/sub 3/O/sub 4/ and combinations thereof. In scavenging hydrogen sulfide, the iron oxide particles are suspended in a liquid which enters into intimate mixing contact with hydrocarbon gases; the hydrogen sulfide is reacted at an exceptional rate and only acid-stable reaction products are formed. Thereafter, the sweetened hydrocarbon gases are collected.

  9. Local Interactions and Non-Abelian Quantum Loop Gases

    NASA Astrophysics Data System (ADS)

    Troyer, Matthias; Trebst, Simon; Shtengel, Kirill; Nayak, Chetan

    2008-12-01

    Two-dimensional quantum loop gases are elementary examples of topological ground states with Abelian or non-Abelian anyonic excitations. While Abelian loop gases appear as ground states of local, gapped Hamiltonians such as the toric code, we show that gapped non-Abelian loop gases require nonlocal interactions (or nontrivial inner products). Perturbing a local, gapless Hamiltonian with an anticipated “non-Abelian” ground-state wave function immediately drives the system into the Abelian phase, as can be seen by measuring the Hausdorff dimension of loops. Local quantum critical behavior is found in a loop gas in which all equal-time correlations of local operators decay exponentially.

  10. 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.

  11. EFFECTS OF SOLAR RADIATION ON ORGANIC MATTER CYCLING: FORMATION OF CARBON MONOXIDE AND CARBONYL SULFIDE

    EPA Science Inventory

    The effects of photoinduced processes on carbon cycling and the biospheric emission of two important trace carbon gases--carbon monoxide and carbonyl sulfide-are examined. oth of these gases are likely to play an important role in the biospheric feedbacks that may reinforce or at...

  12. Space Radiation Risk Assessment

    Microsoft Academic Search

    E. Blakely

    2006-01-01

    Evaluation of potential health effects from radiation exposure during and after deep space travel is important for the future of manned missions To date manned missions have been limited to near-Earth orbits with the moon our farthest distance from earth Historical space radiation career exposures for astronauts from all NASA Missions show that early missions involved total exposures of less

  13. Theoretical studies of photodissociation of small molecules of astrophysical importance

    NASA Technical Reports Server (NTRS)

    Saxon, R. P.

    1983-01-01

    The radicals and ions observed in comets result from photodissociation and photoionization of molecules. According to current models, a comet is composed chiefly of a large, solid nucelus of frozen gases (parent molecules) such as H2O, HCN, and NH3. It is believed comets were formed at the same time and in the same region of space as the major planets and that their chemical composition is the same as that of the early solar system. As the comet nears the Sun, the surface heats up, liberating the frozen gases as well as dust particles. Solar radiation photodissociates the parent molecules into fragments that are observed by resonance fluorescence. Both polyatomic molecules, present in the interstellar medium, and cometary radicals were observed. Using laboratory photo-dissociation data and computer models, astronomers are attempting to identify the parent molecules that account for all observed radicals and ions.

  14. 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.

  15. On the relation between stratospheric chlorine/bromine loading and short-lived tropospheric source gases

    NASA Astrophysics Data System (ADS)

    Ko, Malcolm K. W.; Sze, Nien-Dak; Scott, Courtney J.; Weisenstein, Debra K.

    1997-11-01

    Current methods for estimating the concentrations of inorganic chlorine/bromine species (Cly/Bry) in the stratosphere due to decomposition of tropospheric source gases assume that the Cly/Bry concentration in the stratosphere is determined mainly by the balance between production from in situ oxidation of the source gases in the stratosphere and removal by transport of Cly/Bry out of the stratosphere. The rationale being that for source gases whose lifetimes are of the order of several months or longer the concentration of Cly/Bry in the troposphere is small because they are produced at a relatively slow rate and also removed efficiently by washout processes. As a result of the small concentration, the rate at which Cly/Bry is transported to the stratosphere is expected to be small compared to the in situ stratospheric production. Thus the transport of Cly/Bry from the troposphere contributes little to the stratospheric concentration. In contrast, the origin of stratospheric Cly/Bry from reactive source gases with tropospheric lifetimes comparable to the washout lifetime of Cly/Bry (of the order of 10-30 days) in the troposphere is distinctly different. The in situ source in the stratosphere is expected to be significantly smaller because only a small portion of the source gas is expected to survive the troposphere to be transported into this region. At the same time these short-lived source gases produce appreciable amounts of Cly/Bry in the troposphere such that transport to the stratosphere offers a larger source for stratospheric Cly/Bry than in situ production. Thus, for reactive source species, simple methods of estimating the concentration of stratospheric Cly/Bry that ignore the tropospheric contribution will seriously underestimate the loading. Therefore estimation of the stratospheric Cly/Bry loading requires not only measurements of tropospheric source gases but also measurements of Cly/Bry at the tropopause. This paper illustrates the mechanism by using results from a two-dimensional chemistry-transport model. However, in view of the importance of tropospheric transport on stratospheric loading the detailed values should be further evaluated using a three-dimensional model with appropriate treatment of convective transport.

  16. 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...

  17. Estimating the Solubility of Gases in Battery Electrolytes

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Frank, H. A.

    1984-01-01

    Estimates in excellent agreement with experimental values. Simple method proposed for estimating solubility of gases in electrolytes of lithium batteries using expressions for energy of vaporization and for molar volume.

  18. 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...

  19. Conserving Energy by Recovering Heat from Hot Waste Gases

    E-print Network

    Magnuson, E. E.

    1979-01-01

    Intent of this paper is to show how recovery of heat in hot waste gases reduces nation's energy requirements, reduces dependence on foreign fuels, results in quick payoffs on recovery equipment investments, helps maintain production in event...

  20. 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)

  1. 30 CFR 75.322 - Harmful quantities of noxious gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...of noxious or poisonous gases, other than carbon dioxide, shall not exceed the threshold limit values (TLV) as specified and applied...of Governmental Industrial Hygienists in “Threshold Limit Values for Substance in...

  2. 30 CFR 75.322 - Harmful quantities of noxious gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...of noxious or poisonous gases, other than carbon dioxide, shall not exceed the threshold limit values (TLV) as specified and applied...of Governmental Industrial Hygienists in “Threshold Limit Values for Substance in...

  3. 30 CFR 75.322 - Harmful quantities of noxious gases.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...of noxious or poisonous gases, other than carbon dioxide, shall not exceed the threshold limit values (TLV) as specified and applied...of Governmental Industrial Hygienists in “Threshold Limit Values for Substance in...

  4. 30 CFR 75.322 - Harmful quantities of noxious gases.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...of noxious or poisonous gases, other than carbon dioxide, shall not exceed the threshold limit values (TLV) as specified and applied...of Governmental Industrial Hygienists in “Threshold Limit Values for Substance in...

  5. 30 CFR 75.322 - Harmful quantities of noxious gases.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...of noxious or poisonous gases, other than carbon dioxide, shall not exceed the threshold limit values (TLV) as specified and applied...of Governmental Industrial Hygienists in “Threshold Limit Values for Substance in...

  6. Asymptotic Behavior of Rotating Rarefied Gases with Evaporation and Condensation

    E-print Network

    Sharipov, Felix

    INTRODUCTION One of the basic principles of continuum mechanics is the principle of material frame indifference-inertial systems of reference. This principle has no support within the framework of kinetic theory of gases

  7. 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 ...

  8. 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 ...

  9. Catalytic destruction of tars in biomass-derived gases

    SciTech Connect

    Mudge, L K; Baker, E G; Brown, M D; Wilcox, W A

    1988-02-01

    The Biomass and Municipal Waste Technology Division of the US Department of Energy is sponsoring studies at the Pacific Northwest Laboratory on catalytic destruction of condensible hydrocarbons (tars) in biomass-derived gases. Currently gasifiers generate a significant amount of tars in the product gases. These tars create problems with plugging in downstream equipment and with wastewater treatment. Partial oxidation of the gas stream in a secondary fluid bed of catalyst destroys the tars in biomass-derived gases while increasing the energy content of the product gas by over 20%. Catalysts that remain active for tar destruction are used in the secondary reactor which is specially designed to promote destruction of tars and minimize oxidation of combustible gases such as CO and H/sub 2/. Results of studies with different catalysts which have been tested for this application are described.

  10. 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 ...

  11. Neutralization of thoron progeny in gases

    SciTech Connect

    Cheng, Y.S. [Inhalation Toxicology Research Institute, Albuquerque, NM (United States); Yu, C.C.; Tung, C.J. [National Tsing Hua Univ., Hsinchu (Taiwan, Province of China); Hopke, P.K. [Clarkson Univ., Potsdam, NY (United States)

    1994-08-01

    This paper reports charge neutralization phenomena of {sup 212}Pb particles in nitrogen or oxygen atmospheres with trace amounts of other gases. Newly produced thoron or radon progeny are positively charged, stable molecular clusters that are subsequently neutralized by several mechanisms. The charged clusters have a smaller diffusion coefficient than neutral clusters of the same size due to the interaction of the charge with the surrounding gas molecules. In this study, the authors have found that the diffusion coefficients of {sup 212}Pb in O{sub 2}, N{sub 2}, NH{sub 3}/O{sub 2}, NH{sub 3}/N{sub 2}, and C{sub 6}H{sub 12}/N{sub 2} (IPs between 15.58 and 9.8 eV) ranged between 0.015 and 0.030 cm{sup 2} s{sup {minus}1}. In the case of C{sub 6}H{sub 12}/O{sub 2}, NO{sub 2}/O{sub 2}, NO/O{sub 2}, and dimethylamine/O{sub 2} (ionization potential between 9.8 and 8.23 eV), the diffusion coefficients have increased to between 0.046 and 0.69 cm{sup 2} s{sup {minus}1}. These results are consistent with previous results of {sup 218}Po, indicating that charged progeny are neutralized by electron transfer from a gas molecule with a lower ionization potential than lead oxide. They estimate the ionization potential of lead oxide to range between 9.8 and 10.2 eV. {sup 212}Pb was also neutralized by an electron scavenging mechanism in NO{sub 2}/nitrogen. 32 refs., 4 figs., 2 tabs.

  12. 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.

  13. 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.

  14. 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.

  15. RETRIEVAL OF STRATOSPHERIC TRACE GASES FROM SCIAMACHY LIMB MEASUREMENTS

    Microsoft Academic Search

    Sven Kühl; Tim Deutschmann; Walburga Wilms-Grabe; Christoph Friedeburg; Ulrich Platt; Thomas Wagner

    Stratospheric profiles of various trace gases can be retrieved from limb measurements performed by SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument on the ENVISAT satellite. A two-step method is used to retrieve stratospheric distribution of NO2, BrO and OClO. In the first step, slant column densities (SCDs) of the trace gases are derived from the SCIAMACHY limb spectra

  16. 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.

  17. Greenhouse effect of trace gases, 1970-1980

    Microsoft Academic Search

    A. Lacis; J. Hansen; P. Lee; S. Lebedeff; T. Mitchell

    1981-01-01

    Increased abundances were measured for several trace atmospheric gases in the decade 1970-1980. The equilibrium greenhouse warming for the measured increments of CH4, chlorofluorocarbons and N2O is between 50% and 100% of the equilibrium warming for the measured increase of atmospheric CO2 during the same 10 years. The combined warming of CO2 and trace gases should exceed natural global temperature

  18. Novel MRI applications of laser-polarized noble gases

    Microsoft Academic Search

    R. W. Mair; R. L. Walsworth

    2002-01-01

    Gas-phase nuclear magnetic resonance (NMR) has great potential as a probe for a variety of interesting physical and biomedical\\u000a problems that are not amenable to study by water or similar liquid. However, NMR of gases was largely neglected due to the\\u000a low signal obtained from the thermally polarized gases with very low sample density. The advent of optical pumping techniques

  19. Helium isotope ratios in Yellowstone and Lassen Park volcanic gases

    Microsoft Academic Search

    H. Craig; J. E. Lupton; J. A. Welhan; R. Poreda

    1978-01-01

    Helium isotope ratios (³He\\/⁴He) in Lassen Park and Yellowstone Park volcanic gases show large ³He enrichments relative to atmospheric and crustal helium indicating the presence of a dominant mantle-helium component. The ratios in Lassen helium are 8 times atmospheric in acid hot spring gases, and about 3 times atmospheric in the gas phase in near-neutral high-temperature waters; the acid-spring helium

  20. Transonic flows of dense gases over finite wings

    Microsoft Academic Search

    P. Cinnella

    2008-01-01

    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 Gamma. As a consequence, they display, in the transonic and supersonic regime, nonclassical gas dynamic behaviors,

  1. Measuring OH Reaction Rate Constants and Estimating the Atmospheric Lifetimes of Trace Gases.

    NASA Astrophysics Data System (ADS)

    Orkin, Vladimir; Kurylo, Michael

    2015-04-01

    Reactions with hydroxyl radicals and photolysis are the main processes dictating a compound's residence time in the atmosphere for a majority of trace gases. In case of very short-lived halocarbons their reaction with OH dictates both the atmospheric lifetime and active halogen release. Therefore, the accuracy of OH kinetic data is of primary importance for the comprehensive modeling of a compound's impact on the atmosphere, such as in ozone depletion (i.e., the Ozone Depletion Potential, ODP) and climate change (i.e., the Global Warming Potential, GWP), each of which are dependent on the atmospheric lifetime of the compound. We have demonstrated the ability to conduct very high accuracy determinations of OH reaction rate constants over the temperature range of atmospheric interest, thereby decreasing the uncertainty of kinetic data to 2-3%. The atmospheric lifetime of a well-mixed compound due to its reaction with tropospheric hydroxyl radicals can be estimated by using a simple scaling procedure that is based on the results of field observations of methyl chloroform concentrations and detailed modeling of the OH distribution in the atmosphere. The currently available modeling results of the atmospheric fate of various trace gases allow for an improved understanding of the ability and accuracy of simplified semi-empirical estimations of atmospheric lifetimes. These aspects will be illustrated in this presentation for a variety of atmospheric trace gases.

  2. Emissions of greenhouse gases in the United States, 1987--1994

    SciTech Connect

    NONE

    1995-09-25

    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--1992, with annual updates thereafter. This is the third annual update report,covering national emissions over the period 1987--1993, with preliminary estimates of US carbon dioxide and halocarbon emissions for 1994. Calculating national aggregate emissions(or ``national inventories``) of greenhouse gases is a recently developed form of intellectual endeavor. Greenhouse gas emissions are rarely measured directly or reported to statistical agencies. Thus, to prepare emissions inventories usually requires inferring emissions indirectly from information collected for other purposes. Both the available information and the inferences drawn may be of varying reliability. 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. Chapters 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.

  3. 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.

  4. Large current radiator for the short electromagnetic pulses radiation

    Microsoft Academic Search

    Gennadiy P. Pochanin

    1998-01-01

    One of the most important problems in modern ground penetrating radar design is creating the ultra wide band (UWB) antennas for short sounding electromagnetic pulses (SP) radiation. One of the promising UWB\\/SP radiators is the Large Current Radiator (LCR). This report discusses the performance of an improved design of a LCR

  5. 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.

  6. Slow-light polaritons in Rydberg gases

    NASA Astrophysics Data System (ADS)

    Fleischhauer, Michael

    2012-02-01

    Slow-light polaritons are quasi-particles generated in the interaction of photons with laser-driven atoms with a ?- or ladder-type coupling scheme under conditions of electromagnetically induced transparency (EIT). They are a superposition of electromagnetic and collective spin excitations. If one of the states making up the atomic spin is a high lying Rydberg level, the polaritons are subject to a strong and non-local interaction mediated by a dipole-dipole or van-der Waals coupling between excited Rydberg atoms. I will present and discuss an effective many-body model for these Rydberg polaritons. Depending on the detuning of the control laser the interaction potential between the polaritons can be repulsive or attractive and can have a large imaginary component for distances less than the so-called blockade radius. The non-local effective interaction gives rize to interesting many-body phenomena such as the generation of photons with an avoided volume, visible in stronlgy suppressed two-particle correlations inside the blockade volume. Moreover the long-range, power-law scaling of the interaction can in the repulsive case give rize to the formation of quasi-crystalline structures of photons. In a one dimensional system the low-energy dynamics of the polaritons can be described in terms of a Luttinger liquid. Using DMRG simulations the Luttinger K parameter is calculated and conditions for the formation of a quasi-crystal are derived. When confined to a two-dimensional geometry, e.g. using a resonator with quasi-degenerate transversal mode spectrum, Rydberg polaritons are an interesting candidate to study the bosonic fractional quantum Hall effect. I will argue that the formation of photons with an avoided volume is essential for explaining recent experiments on stationary EIT in Rydberg gases [1,2].[4pt] [1] J.D. Pritchard et al., Phys. Rev. Lett. 105, 193603 (2010). [0pt] [2] D. Petrosyan, J. Otterbach, and M. Fleischhauer, arXiv:1106.1360

  7. Monitoring of air pollutants and green house gases

    SciTech Connect

    Sharma, M. [Assam Girl`s Polytechnic Institute (India)

    1996-12-31

    The study of chemical reactions in the atmosphere poses a serious problem due to the very low concentrations involved, which makes the detection and analysis of reaction products extremely difficult. High altitude reactions at very low pressure cannot be simulated in the laboratory. Chemicals in the atmosphere participate in photochemical reactions by absorption of solar radiation. Such reaction occurs even at the absence of chemical catalysts at much lower temperatures. These photochemical reactions play a key role in governing the ultimate fate of a chemical in the atmosphere. It should be noted that the atmosphere is a tremendously dynamic system with wide fluctuations of the parameters, viz composition, temperature, humidity and intensity of sunlight. Obviously, different processes will be observed under varying atmospheric conditions. Some typical chemical and photochemical reactions will be illustrated. In this context, it must be mentioned that while oxygen plays an important role in the troposphere, ozone plays an important as well as key role in the stratosphere.

  8. Radiation therapy

    MedlinePLUS

    Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells. ... radiation is most harmful to quickly growing cells, radiation therapy damages cancer cells more than normal cells. This ...

  9. Process for removing hydrogen sulfide from gases particularly coal pyrolysis gases

    SciTech Connect

    Ritter, H.; Herpers, E.T.

    1985-02-12

    Hydrogen sulfide is first removed by ammoniacal liquor from coke oven gas in the bottom part of a gas scrubber. In the top part of the scrubber, two consecutively-arranged fine scrubbing stages remove hydrogen sulfide by treating the gases, in the upper stage, with a caustic soda solution or a caustic potash solution. Beneath the upper scrubbing stage is the second fine scrubbing stage fed with a subflow of an aqueous carbonate solution collecting at the outlet of the upper fine scrubbing stage and a subflow of cooled, regenerated carbonate solution discharged from the hydrogen-sulfide/hydrogen-cyanide stripper. From the hydrogen-sulfide/hydrogen-cyanide stripper, a second subflow is admixed with coal liquor for removing fixed ammonia therefrom in a separator. The separator produces water vapor with carbon dioxide vapors that are delivered to the hydrogen-sulfide/hydrogen-cyanide stripper for regenerating the aqueous carbonate washing solution.

  10. Fluid clathrate system for continuous removal of heavy noble gases from mixtures of lighter gases

    DOEpatents

    Gross, Kenneth C. (Bolingbrook, IL); Markun, Francis (Joliet, IL); Zawadzki, Mary T. (South Bend, IN)

    1998-01-01

    An apparatus and method for separation of heavy noble gas in a gas volume. An apparatus and method have been devised which includes a reservoir containing an oil exhibiting a clathrate effect for heavy noble gases with a reservoir input port and the reservoir is designed to enable the input gas volume to bubble through the oil with the heavy noble gas being absorbed by the oil exhibiting a clathrate effect. The gas having reduced amounts of heavy noble gas is output from the oil reservoir, and the oil having absorbed heavy noble gas can be treated by mechanical agitation and/or heating to desorb the heavy noble gas for analysis and/or containment and allow recycling of the oil to the reservoir.

  11. Fluid clathrate system for continuous removal of heavy noble gases from mixtures of lighter gases

    DOEpatents

    Gross, K.C.; Markun, F.; Zawadzki, M.T.

    1998-04-28

    An apparatus and method are disclosed for separation of heavy noble gas in a gas volume. An apparatus and method have been devised which includes a reservoir containing an oil exhibiting a clathrate effect for heavy noble gases with a reservoir input port and the reservoir is designed to enable the input gas volume to bubble through the oil with the heavy noble gas being absorbed by the oil exhibiting a clathrate effect. The gas having reduced amounts of heavy noble gas is output from the oil reservoir, and the oil having absorbed heavy noble gas can be treated by mechanical agitation and/or heating to desorb the heavy noble gas for analysis and/or containment and allow recycling of the oil to the reservoir. 6 figs.

  12. Instantaneous and efficient surface wave excitation of a low pressure gas or gases

    SciTech Connect

    Levy, D.J.; Berman, S.M.

    1988-12-20

    This patent describes a fluorescent lamp illumination system for substantially instantaneously providing partial ionization of a low pressure fill of gas or mixture of gases in a tube and subsequent continuous excitation of the low pressure gas or gases in a surface wave mode for emitting light along the length of the tube, comprising: a source of rf energy; a fill of a permanent, particular volume of low pressure inert gas or gases and mercury vapor; an elongated cylindrical tubular discharge container for confining the fill therein and having first and second closed ends and a cylindrical wall that is optically transparent to visible radiation, the wall having an inner surface and an outer surface, the container being permanently sealed to contain the fill, the inner surface of the discharge container being coated with phosphor the fill being in direct contact with the phosphor; coupling means having a predetermined impedance and responsive to rf energy from the rf source to couple the energy to the fill to both ionize at least a portion of the fill to create a weakly ionized plasma and to deliver the rf energy in a surface wave mode to energize the fill to sustain the plasma, a majority of the energy being delivered through the wall to an area near the inner surface to thereby instantaneously ionize and substantially continuously excite the fill so that the majority of mercury atoms of the mercury vapor near the inner surface produce u.v. photons that interact with the phosphor to produce visible light.

  13. Atmospheric Removal of Very Long-lived Greenhouse Gases in the Mesosphere

    NASA Astrophysics Data System (ADS)

    Totterdill, A.; Kovacs, T.; Gomez Martin, J.; FENG, W.; Chipperfield, M.; Plane, J. M.

    2013-12-01

    Chlorofluorocarbons are known to have serious ozone depleting and global warming potentials. Perfluorinated compounds such as SF6, NF3, SF5CF3 and CF3CF2Cl which have very long lifetimes (ranging from a few centuries to over 3000 years) are too stable to affect stratospheric ozone but do have among the highest per molecule radiative forcing of any greenhouse pollutant, making them extremely potent greenhouse gases. Due to the stability of these gases in the lower atmosphere, mesospheric loss processes could significantly reduce their estimated atmospheric lifetimes and hence, overall climate impact. Potential sinks include reactions with metals and energetic particles such as electrons or short wavelength photons already present in the upper atmosphere. The metals, in this instance iron, sodium or potassium, are produced by meteoric ablation, while background and energetic electrons have the continuous source of photoionization and auroral precipitation, respectively. In this study we investigate the removal potentials of four very long lived gases (SF6, NF3, SF5CF3 and CF3CF2Cl). First, by four metals (Fe, Mg, Na and K), where rate coefficients are measured using the Fast Flow Tube and Pulsed Laser Flash Photolysis / Laser Induced Fluorescence techniques. Second, removal by electron attachment was investigated using a quadrupole mass spectrometer. measurements. Third, Lyman-alpha (121.56 nm) photolysis was measured in a VUV absorption cell. The resulting removal rate coefficients are currently being input into the Whole Atmosphere Community Climate Model (WACCM) to obtain lifetime measurements for these species.

  14. A 1-D modelling of climatic and chemical effects of greenhouse gases

    NASA Astrophysics Data System (ADS)

    Vupputuri, R. K. R.; Higuchi, K.; Hengeveld, H. G.

    1995-09-01

    A coupled 1-D time-dependent radiative-convective-photochemical diffusion model which extends from the surface to 60 km is used to investigate the potential impact of greenhouse trace gas emissions on long-term changes in global climate, atmospheric ozone and surface UV-B radiation, taking into accoont the influence of aerosol loading into the atmosphere from major volcanic eruptions, of thermal inertia of the upper mixed layer of the ocean and of other radiativephotochemical feedback mechanisms. Experiments are carried out under global and annual average insolation and cloudiness conditions. The transient calculations are made for three different growth scenarios for increase in trace gas concentrations. Scenario 1, which begins in 1850, uses the best estimate values for future trace gas concentrations of CO2, CH4, N2O, CFC-11, CFC-12 and tropospheric O3, based on current observational trends. Scenarios 2 and 3, which begin in 1990, assume lower and upper ranges, respectively, of observed growth rates to estimate future concentrations. The transient response of the model for Scenario 1 suggests that surface warming of the ocean mixed layer of about 1 K should have taken place between 1850 and 1990 due to a combined increase of atmospheric CO2 and other trace gases. For the three scenarios considered in this study, the cumulative surface warming induced by all major trace gases for the period 1850 to 2080 ranges from 2.7 K to 8.2 K with the best estimate value of 5 K. The results indicate that the direct and the indirect chemistry-climate interactions of non-CO2 trace gases contribute significantly to the cumulative surface warming (up to 65% by the year 2080). The thermal inertia of a mixed layer of the ocean is shown to have the effect of delaying equilibrium surface warming by almost three decades with an e-folding time of about 5 years. The volcanic aerosols which would result from major volcanic eruptions play a significant role by interrupting the long-term greenhouse surface warming trend and replacing it by a temporary cooling on a time scale of a decade or less. Furthermore, depending on the scenario used, a reduction in the net ozone column could result in an increase in the solar UV-B radiation at the surface by as much as 300% towards the end of 21st century.

  15. Signatures of pairing and spin-orbit coupling in correlation functions of Fermi gases

    NASA Astrophysics Data System (ADS)

    Wu, Chien-Te; Anderson, Brandon M.; Boyack, Rufus; Levin, K.

    2015-06-01

    We derive expressions for density-density and spin-spin correlation functions in the (greatly enhanced) pseudogap phase of spin-orbit-coupled Fermi gases. Density-density correlation functions are found to be relatively insensitive to the presence of these Rashba spin-orbit effects. To arrive at spin-spin correlation functions we derive new f -sum rules, valid even in the absence of a spin conservation law. Our spin-spin correlation functions are shown to be fully consistent with these f -sum rules. Importantly, they provide a clear signature of the Rashba band structure and separately help to establish the presence of a pseudogap.

  16. Payload dose rate from direct beam radiation and exhaust gas fission products. [for nuclear engine for rocket vehicles

    NASA Technical Reports Server (NTRS)

    Capo, M. A.; Mickle, R.

    1975-01-01

    A study was made to determine the dose rate at the payload position in the NERVA System (1) due to direct beam radiation and (2) due to the possible effect of fission products contained in the exhaust gases for various amounts of hydrogen propellant in the tank. Results indicate that the gamma radiation is more significant than the neutron flux. Under different assumptions the gamma contribution from the exhaust gases was 10 to 25 percent of total gamma flux.

  17. Characterization and origin of natural gases of the Anadarko Basin

    USGS Publications Warehouse

    Rice, Dudley D.; Threlkeld, Charles N.; Buletich, April K.

    1989-01-01

    Natural-gas production in the Anadarko basin is from three geographically separated areas that can be differentiated by age of reservoir and by inferred nature of thermal origin of the gases. In the central basin, nonassociated gases are produced mainly from Upper Mississippian and Pennsylvanian sandstones. Gases become isotopically heavier (?13C1 values range from -49.8 to -33.2 ppt) and chemically drier (C1/C1–5 values range from 0.74 to 0.99) with increasing level of thermal maturity. Gas samples are from depths as much as 21,600 ft. Gases were generated mainly from interbedded shales with type-III kerogen during the mature and postmature stages of hydrocarbon generation. Deviations from the trend are due to mixing and migration of gases generated at different levels of thermal maturity over the past 250 m.y. In the giant Panhandle-Hugoton field, nonassociated gases are generally produced from Permian carbonates at depths 13C1 values range from -46.4 to -39.9 ppt, C1/C1–5 values range from 0.69 to 0.96). Because organic-rich, mature source rocks are not present in the area, gases probably were generated in the central basin from Pennsylvanian or older source rocks during the mature stage of hydrocarbon generation. This implies migration over distances as much as several hundred miles. In the Sooner trend, associated gases are produced from Silurian, Devonian, and Mississippian carbonates at depths as great as 9,600 ft and were generated from type-II kerogen during the mature stage of hydrocarbon generation. Associated oil correlates with extracts of the Upper Devonian and Lower Mississippian Woodford Shale. Gases are isotopically lighter (?13C1 values of -47.3 to -40.6 ppt) and chemically wetter (C1/C1–5 values of 0.67 to 0.99) than those derived from type-III kerogen at an equivalent level of thermal maturity.

  18. Aspects of superfluid cold atomic gases in optical lattices

    NASA Astrophysics Data System (ADS)

    Watanabe, Gentaro; Yoon, Sukjin

    2013-08-01

    We review our studies on Bose and Fermi superfluids of cold atomic gases in optical lattices at zero temperature. Especially, we focus on superfluid Fermi gases along the crossover between the Bardeen-Cooper-Schrieffer (BCS) and the Bose-Einstein condensate (BEC) states, which enable us to study the Bose and the Fermi superfluids in a unified point of view. We discuss basic static and long-wavelength properties (such as the equation of state, incompressibility, and effective mass), energetic stability, and energy band structures of the superfluid Fermi gases in an optical lattice periodic along one spatial direction. The periodic potential causes pairs of atoms to be strongly bound, and this can affect the static and long-wavelength properties and the stability of the superflow. Regarding the band structure, a peculiar loop structure called "swallowtail" can appear in superfluid Fermi gases and in the Bose case, but the mechanism of emergence in the Fermi case is very different from that in bosonic case. Other quantum phases that the cold atomic gases in optical lattices can show are also briefly discussed based on their roles as quantum simulators of Hubbard models.

  19. Data for modeling of positron collisions and transport in gases

    NASA Astrophysics Data System (ADS)

    Petrovi?, Z. Lj.; Bankovi?, A.; Dujko, S.; Marjanovi?, S.; Malovi?, G.; Sullivan, J. P.; Buckman, S. J.

    2013-07-01

    We review the current status of positron cross sections for collisions with atoms and molecules from the viewpoint of their use in studies of positron transport processes in gases, liquids and human tissue. The data include cross sections for positron scattering in rare gases, molecular gases (eg., for N2, H2, CO2, CF4) and in particular for organic molecules and those relevant for applications in medicine (e.g. formic acid and water vapor). The cross sections were taken from an assessment of previously published positron-target cross sections. All of the cross sections are based on binary collision measurements and theoretical calculations, and they were not explicitly modified according to the standard swarm analysis. The main reason for this is systematic lack of experimental data for positron transport properties in gases. However, we believe that our compiled sets of cross sections are at level of sophistication, and of sufficient accuracy, to provide correct interpretation of future positron-based experiments. Using these cross sections as an input in our Monte Carlo simulations and Boltzmann equation treatment, we review some interesting points observed in the profiles of various transport coefficients for positrons in gases. Particular emphasis is placed upon the analysis of kinetic phenomena generated by the explicit influence of Ps formation.

  20. Simulations of greenhouse trace gases using the Los Alamos chemical tracer model

    SciTech Connect

    Kao, C.Y.J.; Morz, E. (Los Alamos National Lab., NM (United States)); Tie, X. (Scripps Institution of Oceanography, San Diego, CA (United States))

    1991-11-01

    Through three-dimensional global model studies on atmospheric composition and transport, we are improving our quantitative understanding of the origins and behavior of trace gases that affect Earth's radiative energy balance and climate. We will focus, in this paper, on the simulations of three individual trace gases including CFC-11, methyl chloroform, and methane. We first used our chemical tracer model to study the global distribution and trend of chemically inert CFC-11 observed by the Atmospheric Lifetime Experiment. The results show that the model has the ability to reproduce the time-series of the observations. The purpose of this CFC-11 simulation was to test the transport of the model. We then used to model introduce methyl chloroform into the atmosphere according to the known emission patterns and iteratively varied OH fields so that the observed concentrations of methyl chloroform from the observations could be simulated well. The rationale behind this approach is that the reaction with OH is the dominant sink for metyl chloroform and the transport of the model has been tested in the previous CFC-11 study. Finally, using the inferred OH distributions, we conducted a steady-state simulation to reproduce the current methane distribution. The general agreement between the modeled an observed methane surface concentrations has laid a foundation for the simulation of the transient increase of methane.

  1. Simulations of greenhouse trace gases using the Los Alamos chemical tracer model

    SciTech Connect

    Kao, C.Y.J.; Morz, E. [Los Alamos National Lab., NM (United States); Tie, X. [Scripps Institution of Oceanography, San Diego, CA (United States)

    1991-11-01

    Through three-dimensional global model studies on atmospheric composition and transport, we are improving our quantitative understanding of the origins and behavior of trace gases that affect Earth`s radiative energy balance and climate. We will focus, in this paper, on the simulations of three individual trace gases including CFC-11, methyl chloroform, and methane. We first used our chemical tracer model to study the global distribution and trend of chemically inert CFC-11 observed by the Atmospheric Lifetime Experiment. The results show that the model has the ability to reproduce the time-series of the observations. The purpose of this CFC-11 simulation was to test the transport of the model. We then used to model introduce methyl chloroform into the atmosphere according to the known emission patterns and iteratively varied OH fields so that the observed concentrations of methyl chloroform from the observations could be simulated well. The rationale behind this approach is that the reaction with OH is the dominant sink for metyl chloroform and the transport of the model has been tested in the previous CFC-11 study. Finally, using the inferred OH distributions, we conducted a steady-state simulation to reproduce the current methane distribution. The general agreement between the modeled an observed methane surface concentrations has laid a foundation for the simulation of the transient increase of methane.

  2. Evolution of Gases and Particles from a Savanna Fire in South Africa

    NASA Technical Reports Server (NTRS)

    Hobbs, Peter V.; Sinha, Parikhit; Yokelson, Robert J.; Christian, Ted J.; Blake, Donald R.; Gao, Song; Kirchstetter, Thomas W.; Novakov, Tica; Pilewskie, Peter

    2003-01-01

    Airborne measurements of particles and gases fiom a 1000-ha savanna fire in South Africa are presented. These measurements represent the most extensive data set reported on the aging of biomass smoke. The measurements include total concentrations of particles (CN), particle sizes, particulate organic carbon and black carbon, light-scattering coefficients, downwelling UV fluxes, and mixing ratios for 42 trace gases and 7 particulate species. The ratios of excess nitrate, ozone, and gaseous acetic acid to excess CO increased significantly as the smoke aged over approximately 40-45 min, indicating that these species were formed by photochemistry in the plume. For 17 other species, the excess mixing ratio normalized by the excess mixing ratio of CO decreased significantly with ' smoke age. The relative rates of decrease for a number of chemical species imply that the average OH concentration in the plume was approximately 1.7 x l0(exp 7) molecules /cubic centimeter. Excess CN, normalized by excess CO, decreased rapidly during the first approximately 5 min of aging, probably due to coagulation, and then increased, probably due to gas-to-particle conversion. The CO-normalized concentrations of particles < 1.5 microns in diameter decreased, and particles >1.5 micron diameter increased, with smoke age. The spectral depletion of solar radiation by the smoke is depicted. The downwelling UV flux near the vertical center of the plume was about two-thirds of that near the top of the plume.

  3. Green House Gases Measurement At Maitri, Antarctica

    Microsoft Academic Search

    S. L. Jain; S. D. Ghude; B. C. Arya

    2004-01-01

    The earth's environment is constantly changing. The scientific evidence indicates that these changes are result of a complex interplay among a number of natural and human related systems. Therefore in the recent times, concern has grown about global change - which is related to natural and anthropogenic alteration of the Earth's environment. Among them the important issues, which are dangerous

  4. Radiation measured with different dosimeters during STS121 space mission

    Microsoft Academic Search

    D. Zhou; E. Semones; R. Gaza; S. Johnson; N. Zapp; M. Weyland; R. Rutledge; T. Lin

    2009-01-01

    Radiation impact to astronauts depends on the particles’ linear energy transfer (LET) and is dominated by high LET radiation. Radiation risk experienced by astronauts can be determined with the radiation LET spectrum measured and the risk response function obtained from radiobiology. Systematical measurement of the space radiation is an important part for the research on the impact of radiation to

  5. Method for removing acid gases from a gaseous stream

    DOEpatents

    Gorin, Everett (San Rafael, CA); Zielke, Clyde W. (McMurray, PA)

    1981-01-01

    In a process for hydrocracking a heavy aromatic polynuclear carbonaceous feedstock containing reactive alkaline constituents to produce liquid hydrocarbon fuels boiling below about 475.degree. C. at atmospheric pressure by contacting the feedstock with hydrogen in the presence of a molten metal halide catalyst, thereafter separating a gaseous stream containing hydrogen, at least a portion of the hydrocarbon fuels and acid gases from the molten metal halide and regenerating the molten metal halide, thereby producing a purified molten metal halide stream for recycle to the hydrocracking zone, an improvement comprising; contacting the gaseous acid gas, hydrogen and hydrocarbon fuels-containing stream with the feedstock containing reactive alkaline constituents to remove acid gases from the acid gas containing stream. Optionally at least a portion of the hydrocarbon fuels are separated from gaseous stream containing hydrogen, hydrocarbon fuels and acid gases prior to contacting the gaseous stream with the feedstock.

  6. Lattice vibrations of pure and doped GaSe

    SciTech Connect

    Allakhverdiev, K. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey) and Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan)]. E-mail: kerim.allahverdi@mam.gov.tr; Baykara, T. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey); Ellialtioglu, S. [Department of Physics, Middle East Technical University, Ankara 06531 (Turkey); Hashimzade, F. [Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan); Huseinova, D. [Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan); Kawamura, K. [Institute of Materials Science, University of Tsukuba 305-8573 (Japan); Kaya, A.A. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey); Kulibekov, A.M. [Department of Physics, Mugla University, Mugla 48000 (Turkey); Onari, S. [Institute of Materials Science, University of Tsukuba 305-8573 (Japan)

    2006-04-13

    The Bridgman method is used to grow especially undoped and doped single crystals of GaSe. Composition and impurity content of the grown crystals were determined using X-ray fluorescence (XRF) method. X-ray diffraction, Raman scattering, photoluminescence (PL), and IR transmission measurements were performed at room temperature. The long wavelength lattice vibrations of four modifications of GaSe were described in the framework of modified one-layer linear-chain model which also takes into consideration the interaction of the selenium (Se) atom with the second nearest neighbor gallium (Ga) atom in the same layer. The existence of an eight-layer modification of GaSe is suggested and the vibrational frequencies of this modification are explained in the framework of a lattice dynamical model considered in the present work. Frequencies and the type of vibrations (gap, local, or resonance) for the impurity atoms were calculated and compared with the experimental results.

  7. Radon in fumarolic gases from vulcano island (Sicily, Italy)

    SciTech Connect

    Cioni, R.; Corazza, E.; D'Amore, F.

    1984-01-01

    In this study, Radon-222 activity was measured sporadically in fumarolic gases from the island of Vulcano (Italy) between 1978 and 1980. Rn variations in the crater fumaroles (300/sup 0/C) were found to be correlated with microseismic activity; they also correlate positively with water and negatively with the S/C1 ratio. On the basis of a geochemical model, the fumarolic gases at Vulcano are assumed to be a mixture of deep magmatic gases and fluids from shallow aquifers. Rn is carried by these fluids (an average of 500 nCi per kg of fluid). Circulating water can strip Rn from the U-rich rocks on Vulcano. At present it is impossible to determine whether microseismicity is producing composition changes, or vice versa, or whether both are the consequence of a main volcano-tectonic event.

  8. “Hard probes” of strongly-interacting atomic gases

    SciTech Connect

    Nishida, Yusuke [Los Alamos National Laboratory

    2012-06-18

    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 a spin-1/2 Fermi gas and in a spinless Bose gas. Reasonable agreement with recent quantum Monte Carlo simulations even at a relatively small momentum k/kF > 1.5 indicates that our large-momentum expansions are valid in a wide range of momentum. We also study a differential scattering rate when a probe atom is shot into atomic gases. Because the number density and current density of the target atomic gas contribute to the forward scattering only, its contact density (measure of short-range pair correlation) gives the leading contribution to the backward scattering. Therefore, such an experiment can be used to measure the contact density and thus provides a new local probe of strongly interacting atomic gases.

  9. Formation of particle agglomerates after switching fluidizing gases

    SciTech Connect

    Kai, Takami; Takahashi, Takeshige [Kagoshima Univ. (Japan). Dept. of Applied Chemistry and Chemical Engineering] [Kagoshima Univ. (Japan). Dept. of Applied Chemistry and Chemical Engineering

    1997-02-01

    When a fluidizing gas is switched from a low-density gas to a high-density gas, particles in the emulsion phase agglomerate and bubbles disappear. At the same time, channeling occurs and a decrease in the pressure drop over the bed is observed. The disturbance of fluidization is temporary, and normal fluidization is restored after several minutes. The study of mechanisms of the transient phenomena shows that the difference in diffusion rates of the two gases in the emulsion phase caused the agglomeration of particles. Because the mobility of particles was reduced, channels were formed and the fluidizing gas bypassed through them. Effects of the properties of the fluidizing gases and particles on the intensity of the transient phenomena were also studied. The intensity increased with increasing difference in the densities of the two gases. The transient phenomena were considerable for small- and light-particle systems.

  10. Are recent Arctic ozone losses caused by increasing greenhouse gases?

    NASA Astrophysics Data System (ADS)

    Rieder, Harald E.; Polvani, Lorenzo M.

    2013-08-01

    has been suggested that the Arctic ozone losses observed in recent years might be a manifestation of climate change due to increasing greenhouse gases. We here offer evidence to the contrary, by focusing on the volume of polar stratospheric clouds (VPSC), a convenient proxy for polar ozone loss whose simplicity allows for easily reproducible results. First, we analyze the time series of VPSC in three reanalysis data sets and find no statistically significant trends in VPSC-nor changes in their probability density functions-over the period 1979-2011. Second, we analyze VPSC in a stratosphere-resolving chemistry-climate model forced uniquely with increasing greenhouse gases following the A1B scenario: here too, we find no significant changes in VPSC over the entire 21st century. Taken together, these results strongly suggest that the sporadic high ozone losses in recent years have not been caused by increasing greenhouse gases.

  11. Are recent Arctic ozone losses caused by increasing greenhouse gases?

    NASA Astrophysics Data System (ADS)

    Rieder, H.; Polvani, L. M.

    2013-12-01

    It has been suggested that the Arctic ozone losses observed in recent years might be a manifestation of climate change due to increasing greenhouse gases. We here offer evidence to the contrary, by focusing on the volume of polar stratospheric clouds (VPSC), a convenient proxy for polar ozone loss whose simplicity allows for easily reproducible results. First, we analyze the time series of VPSC in three reanalysis datasets and find no statistically significant trends in VPSC - nor changes in their probability density functions - over the period 1979-2011. Second, we analyze VPSC in a stratosphere-resolving chemistry-climate model forced uniquely with increasing greenhouse gases following the A1B scenario: here too, we find no significant changes in VPSC over the entire 21st century. Taken together, these results strongly suggest that the sporadic high ozone losses in recent years have not been caused by increasing greenhouse gases.

  12. Optical and spin polarization dynamics in GaSe nanoslabs

    NASA Astrophysics Data System (ADS)

    Tang, Yanhao; Xie, Wei; Mandal, Krishna C.; McGuire, John A.; Lai, C. W.

    2015-05-01

    We report nearly complete preservation of "spin memory" between optical absorption and photoluminescence (PL) in nanometer slabs of GaSe pumped with up to 0.2 eV excess energy. At cryogenic temperatures, the initial degree of circular polarization (?0) of PL approaches unity, with the major fraction of the spin polarization decaying with a time constant >500 ps in sub-100-nm GaSe nanoslabs. Even at room temperature, ?0 as large as 0.7 is observed, while pumping 1 eV above the band edge yields ?0=0.15 . Angular momentum preservation for both electrons and holes is due to the separation of the nondegenerate conduction and valence bands from other bands. In contrast to valley polarization in atomically thin transition-metal dichalcogenides, here optical spin polarization is preserved in nanoslabs of 100 layers or more of GaSe.

  13. Spinor Bose gases: Symmetries, magnetism, and quantum dynamics

    NASA Astrophysics Data System (ADS)

    Stamper-Kurn, Dan M.; Ueda, Masahito

    2013-07-01

    Spinor Bose gases form a family of quantum fluids manifesting both magnetic order and superfluidity. This article reviews experimental and theoretical progress in understanding the static and dynamic properties of these fluids. The connection between system properties and the rotational symmetry properties of the atomic states and their interactions are investigated. Following a review of the experimental techniques used for characterizing spinor gases, their mean-field and many-body ground states, both in isolation and under the application of symmetry-breaking external fields, are discussed. These states serve as the starting point for understanding low-energy dynamics, spin textures, and topological defects, effects of magnetic-dipole interactions, and various nonequilibrium collective spin-mixing phenomena. The paper aims to form connections and establish coherence among the vast range of works on spinor Bose gases, so as to point to open questions and future research opportunities.

  14. The Marginal Damage Costs of Different Greenhouse Gases: An Application of FUND

    SciTech Connect

    Waldhoff, Stephanie T.; Anthoff, David; Rose, Steven K.; Tol, Richard

    2014-01-01

    We use FUND 3.8 to estimate the social cost of four greenhouse gases: carbon dioxide, methane, nitrous oxide, and sulphur hexafluoride emissions. The damage potential for each gas—the ratio of the social cost of the non-carbon dioxide greenhouse gas to the social cost of carbon dioxide—is also estimated. The damage potentials are compared to several metrics, focusing in particular on the global warming potentials, which are frequently used to measure the trade-off between gases in the form of carbon dioxide equivalents. We find that damage potentials could be significantly higher than global warming potentials. This finding implies that previous papers have underestimated the relative importance of reducing non-carbon dioxide greenhouse gas emissions from an economic damage perspective. We show results for a range of sensitivity analyses: carbon dioxide fertilization on agriculture productivity, terrestrial feedbacks, climate sensitivity, discounting, equity weighting, and socioeconomic and emissions scenarios. The sensitivity of the results to carbon dioxide fertilization is a primary focus as it is an important element of climate change that has not been considered in much of the previous literature. We estimate that carbon dioxide fertilization has a large positive impact that reduces the social cost of carbon dioxide with a much smaller effect on the other greenhouse gases. As a result, our estimates of the damage potentials of methane and nitrous oxide are much higher compared to estimates that ignore carbon dioxide fertilization. As a result, our base estimates of the damage potential for methane and nitrous oxide that include carbon dioxide fertilization are twice their respective global warming potentials. Our base estimate of the damage potential of sulphur hexafluoride is similar to the one previous estimate, both almost three times the global warming potential.

  15. Interaction between fumarolic gases and thermal groundwaters at Vulcano Island (Italy): evidences from chemical composition of dissolved gases in waters

    NASA Astrophysics Data System (ADS)

    Capasso, G.; Favara, R.; Inguaggiato, S.

    2000-11-01

    The chemical composition of some gaseous species dissolved in thermal groundwaters from Vulcano Island was determined directly in the field. The determinations were made using a methodology based on the equilibrium partitioning of gases between a liquid and a gaseous phase. The analyses were performed with a portable gas chromatograph using a simple analytical procedure lasting 70 s. He and CO 2 partial pressures are notably higher than those of waters in equilibrium with the atmosphere confirming an interaction between volcanic gases and groundwaters. The highest CO 2 values were recorded in wells located in areas of anomalous CO 2 and He exhalations related to the active volcano-tectonic structures on the island. The temporal variations in CO 2 concentrations both in the crater fumarolic gases and in the dissolved gases of some wells showed a very similar pattern. Lastly, the lowering of the He contents in the dissolved gases that occurred in 1996-1997 was probably due to a decreased interaction between the main degassing system (crater fumaroles) and the thermal groundwaters.

  16. Identification of gaseous SO2 and new upper limits for other gases on Io

    NASA Technical Reports Server (NTRS)

    Pearl, J.; Hanel, R.; Kunde, V.; Maguire, W.; Fox, K.; Gupta, S.; Ponnamperuma, C.; Raulin, F.

    1979-01-01

    The identification of gaseous sulfur dioxide on Io by Voyager 1 is reported, and preliminary upper limits for other atmospheric gases are presented. Averaged spectra taken by the Voyager IRIS experiment in the range of 1,000 to 1,200/cm are interpreted as containing three fundamental sulfur dioxide bands, with intensities most nearly corresponding to an atmospheric model with a sulfur dioxide abundance of 0.2 cm atm. Upper limits for COS, CS2, SO3, H2S, CO2, O3, N2O, H2O, CH4, NH3 and HC1, not detected in the spectra, were calculated on the basis of the radiative transfer equation for temperatures of 130 and 250 K; a depletion of hydrogen, carbon and nitrogen is noted. It is suggested that a SO2 outgassing from a cooling sulfur extrusion is the major source of the observed atmospheric SO2.

  17. High-order harmonic propagation in gases within the discrete dipole approximation

    SciTech Connect

    Hernandez-Garcia, C.; Perez-Hernandez, J. A.; Ramos, J.; Jarque, E. Conejero; Plaja, L. [Departamento de Fisica Aplicada, Universidad de Salamanca, E-37008 Salamanca (Spain); Roso, L. [Centro de Laseres Pulsados CLPU, E-37008 Salamanca (Spain)

    2010-09-15

    We present an efficient approach for computing high-order harmonic propagation based on the discrete dipole approximation. In contrast with other approaches, our strategy is based on computing the total field as the superposition of the driving field with the field radiated by the elemental emitters of the sample. In this way we avoid the numerical integration of the wave equation, as Maxwell's equations have an analytical solution for an elementary (pointlike) emitter. The present strategy is valid for low-pressure gases interacting with strong fields near the saturation threshold (i.e., partially ionized), which is a common situation in the experiments of high-order harmonic generation. We use this tool to study the dependence of phase matching of high-order harmonics with the relative position between the beam focus and the gas jet.

  18. Method for determining the concentration of atomic species in gases and solids

    DOEpatents

    Loge, G.W.

    1998-02-03

    Method is described for determining the concentration of atomic species in gases and solids. The method involves measurement of at least two emission intensities from a species in a sample that is excited by incident laser radiation. This generates a plasma therein after a sufficient time period has elapsed and during a second time period, permits an instantaneous temperature to be established within the sample. The concentration of the atomic species to be determined is then derived from the known emission intensity of a predetermined concentration of that species in the sample at the measured temperature, a quantity which is measured prior to the determination of the unknown concentration, and the actual measured emission from the unknown species, or by this latter emission and the emission intensity of a species having known concentration within the sample such as nitrogen for gaseous air samples. 4 figs.

  19. Method for determining the concentration of atomic species in gases and solids

    DOEpatents

    Loge, Gary W. (304 Cheryl Ave., Los Alamos, NM 87544)

    1998-01-01

    Method for determining the concentration of atomic species in gases and solids. Measurement of at least two emission intensities from a species in a sample that is excited by incident laser radiation. Which generates a plasma therein after a sufficient time period has elapsed and during a second time period, permits an instantaneous temperature to be established within the sample. The concentration of the atomic species to be determined is then derived from the known emission intensity of a predetermined concentration of that species in the sample at the measured temperature, a quantity which is measured prior to the determination of the unknown concentration, and the actual measured emission from the unknown species, or by this latter emission and the emission intensity of a species having known concentration within the sample such as nitrogen for gaseous air samples.

  20. Analysis of two-phase radiation in thermally developing Poiseuille flow

    SciTech Connect

    Kim, K.M.; Lee, H.J.; Baek, S.W.

    1999-10-01

    Industrial heat processing systems such as boilers, combustors, and gasification plants usually contain some particles as well as hot exhaust gases exceeding 1,000 K. Thereby, thermal analysis of two-phase mixtures in these facilities is very important from the viewpoint of energy savings and performance enhancement. Combined conductive and radiative heat transfer in a thermally developing two-phase Poiseuille flow in a cylindrical duct is studied here. A two-phase radiative transfer equation (RTE) considering radiation by both gas and particles is taken into account. A complex form of nonlinear integrodifferential RTE is solved by the discrete ordinates method (DOM, or so called S{sub N} method) in axisymmetric geometry. After such validation, namely, the solution in a two-dimensional channel flow between two flat plates is compared with that solved by the zone method, the program is then applied to fully developed gas-particle two-phase flow in a cylindrical duct. A parametric study is performed for gas and particle absorption coefficients, particle number density, particle emissivity, and wall emissivity. The results show a significant effect of two-phase radiation on the thermal characteristics. However, in all cases, it was found that conduction is predominant near the wall.