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1

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

Microsoft Academic Search

We describe in detail the instrumentation and calibrations used in the Atmospheric Lifetime Experiment (ALE), the Global Atmospheric Gases Experiment (GAGE), and the Advanced Global Atmospheric Gases Experiment (AGAGE) and present a history of the majority of the anthropogenic ozone-depleting and climate-forcing gases in air based on these experiments. Beginning in 1978, these three successive automated high-frequency in situ experiments

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

2000-01-01

2

Radiative energy transfer in molecular gases  

NASA Technical Reports Server (NTRS)

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.

Tiwari, Surendra N.

1992-01-01

3

Radiative forcings and global warming potentials of 39 greenhouse gases  

Microsoft Academic Search

The radiative forcings and global warming potentials for 39 greenhouse gases are evaluated using narrowband and broadband radiative transfer models. Unlike many previous studies, latitudinal and seasonal variations are considered explicitly, using distributions of major greenhouse gases from a combination of chemical-transport model results and Upper Atmosphere Research Satellite (UARS) measurements and cloud statistics from the International Satellite Cloud Climatology

Atul K. Jain; Bruce P. Briegleb; K. Minschwaner; Donald J. Wuebbles

2000-01-01

4

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

5

Radiative forcings for 28 potential Archean greenhouse gases  

NASA Astrophysics Data System (ADS)

Despite reduced insolation in the late Archean, evidence suggests a~warm climate which was likely sustained by a stronger greenhouse effect, the so-called faint young sun problem (FYSP). CO2 and CH4 are generally thought to be the mainstays of this enhanced greenhouse, though many other gases have been proposed. We present high accuracy radiative forcings for CO2, CH4, and 26 other gases, performing the radiative transfer calculations at line-by-line resolution and using HITRAN 2012 line data for background pressures of 0.5, 1, and 2 bar of atmospheric N2. For CO2 to resolve the FYSP alone at 2.8 Gyr BP (80% of present solar luminosity), 0.32 bar is needed with 0.5 bar of atmospheric N2, 0.20 bar with 1 bar of atmospheric N2, or 0.11 bar with 2 bar of atmospheric N2. For CH4, we find that near-infrared absorption is much stronger than previously thought, arising from updates to the HITRAN database. CH4 radiative forcing peaks at 10.3, 9, or 8.3 W m-2 for background pressures of 0.5, 1, or 2 bar, likely limiting the utility of CH4 for warming the Archean. For the other 26 HITRAN gases, radiative forcings of up to a few to 10 W m-2 are obtained from concentrations of 0.1-1 ppmv for many gases. For the 20 strongest gases, we calculate the reduction in radiative forcing due to overlap. We also tabulate the modern sources, sinks, concentrations, and lifetimes of these gases and summaries the literature on Archean sources and concentrations. We recommend the forcings provided here be used both as a first reference for which gases are likely good greenhouse gases, and as a standard set of calculations for validation of radiative forcing calculations for the Archean.

Byrne, B.; Goldblatt, C.

2014-10-01

6

Radiative forcings for 28 potential Archean greenhouse gases  

NASA Astrophysics Data System (ADS)

Despite reduced insolation in the late Archean, evidence suggests a warm climate which was likely sustained by a stronger greenhouse effect, the so-called Faint Young Sun Problem (FYSP). CO2 and CH4 are generally thought to be the mainstays of this enhanced greenhouse, though many other gases have been proposed. We present high accuracy radiative forcings for CO2, CH4 and 26 other gases, performing the radiative transfer calculations at line-by-line resolution and using HITRAN 2012 line data for background pressures of 0.5, 1, and 2 bar. For CO2 to resolve the FYSP alone, 0.21 bar is needed with 0.5 bar of atmospheric pressure, 0.13 bar with 1 bar of atmospheric pressures, or 0.07 bar with 2 bar of atmospheric pressure. For CH4, we find that near-infrared absorption is much stronger than previously thought, arising from updates to the HITRAN database. CH4 radiative forcing peaks at 10.3, 9, or 8.3 W m-2 for background pressures of 0.5, 1 or 2 bar, likely limiting the utility of CH4 for warming the Archean. For the other 26 HITRAN gases, radiative forcings of up to a few to 10 W m-2 are obtained from concentrations of 0.1-1 ppmv for many gases. We further calculate the reduction of radiative forcing due to gas overlap for the 20 strongest gases. We recommend the forcings provided here be used both as a first reference for which gases are likely good greenhouse gases, and as a standard set of calculations for validation of radiative forcing calculations for the Archean.

Byrne, B.; Goldblatt, C.

2014-05-01

7

Handbook of infrared radiation from combustion gases  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

8

Radiative precursors driven by converging blast waves in noble gases  

NASA Astrophysics Data System (ADS)

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.

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

9

Radiative precursors driven by converging blast waves in noble gases  

SciTech Connect

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.

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

10

Synthetic Lorentz force in classical atomic gases via Doppler effect and radiation pressure  

E-print Network

We theoretically predict a novel type of synthetic Lorentz force for classical (cold) atomic gases, which is based on the Doppler effect and radiation pressure. A fairly uniform and strong force can be constructed for gases in macroscopic volumes of several cubic millimeters and more. This opens the possibility to mimic classical charged gases in magnetic fields, such as those in a tokamak, in cold atom experiments.

Dub?ek, T; Juki?, D; Aumiler, D; Ban, T; Buljan, H

2014-01-01

11

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

Microsoft Academic Search

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

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

2000-01-01

12

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

13

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

SciTech Connect

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

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

2008-04-01

14

Principals Of Radiation Toxicology: Important Aspects.  

NASA Astrophysics Data System (ADS)

“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.

Popov, Dmitri; Maliev, Slava; Jones, Jeffrey

15

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

PubMed Central

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

2012-01-01

16

On the additivity of radiative forcing between land use change and greenhouse gases  

NASA Astrophysics Data System (ADS)

scientific and policy contexts, radiative forcing—an external change in Earth's mean radiative balance—has been suggested as a metric for evaluating the strength of climate perturbations resulting from different climate change drivers such as greenhouse gases and surface physical effects of land use change. However, the utility of this approach has been questioned given the spatially concentrated and sometimes nonradiative nature of land use climate disturbances. Here we show that when negative forcing from agricultural expansion is approximately balanced by a radiatively equivalent increase in atmospheric carbon dioxide, significant changes in temperature, precipitation, and the timing of climate change result. These idealized experiments demonstrate the nonadditivity of radiative forcing from land use change and greenhouse gases and point to the need for new climate change metrics or the development of climate policies and assessment protocols that do not rely on single dimensional metrics.

Jones, Andrew D.; Collins, William D.; Torn, Margaret S.

2013-08-01

17

Monte Carlo Simulation of Radiation in Gases with a NarrowBand Model  

E-print Network

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

Dufresne, Jean-Louis

18

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

19

Radiative forcing by well-mixed greenhouse gases: Estimates from climate models in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4)  

Microsoft Academic Search

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

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

2006-01-01

20

Inadequacy of effective CO2 as a proxy in simulating the greenhouse effect of other radiatively active gases  

NASA Astrophysics Data System (ADS)

The use of an 'effective' CO2 concentration to simulate the combined greenhouse effect of CO2 and the trace gases CH4, N2O, CFC-11 and CFC-12 is open to question, because the radiative-forcing behavior of CO2 is very different from that of these other gases. Model simulations show that different radiative forcing can lead to quite different climatic effects. The thermal infrared opacity of these trace gases therefore needs to be explicitly accounted for when attempting to predict the climate response to increasing concentrations of greenhouse gases.

Wang, Wei-Chyung; Dudek, Michael P.; Liang, Xin-Zhong; Kiehl, J. T.

1991-04-01

21

Airborne Measurements of Important Ozone-depleting and Climate-forcing Trace Gases from 1991 to HIPPO and Beyond  

NASA Astrophysics Data System (ADS)

Through collaborations with the National Aeronautics and Space Administration (NASA) and the National Science Foundation, the National Oceanographic and Atmospheric Administration Earth System Research Laboratory Global Monitoring Division (NOAA/ESRL/GMD) has measured a number of trace gases from manned and unmanned aircraft up to 21 km, and balloon platforms up to 32 km since 1991 at locations spanning the globe. Over 40 trace gases, including nitrous oxide (N2O), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), methyl halides, numerous other halocarbons, sulfur gases (COS, SF6, CS2), and selected hydrocarbons, have been measured at Earth's surface and at altitude. This presentation will highlight our recent observations of halocarbons and other trace gases during the NSF and NOAA sponsored HIAPER Pole-to-Pole Observations (HIPPO) campaigns (2009-2011) that included flyovers of NDACC (Network for the Detection of Atmospheric Composition Change), AGAGE (Advanced Global Atmospheric Gases Experiment), and NOAA stations. Other observations from the recent NASA and NOAA sponsored Unmanned Aircraft Systems (UAS) GloPac and ATTREX campaigns (2010 - present) will also be highlighted, along with comparisons to proximate NDACC and satellite observations (ACE-FTS, Aura MLS and TES instruments). Our goal is to assemble a complete data set of geolocated airborne observations of halocarbons and other important trace gases measured by NOAA/ESRL airborne gas chromatographs for the purpose of facilitating model development and studies of atmospheric chemistry and transport processes in the troposphere and lower stratosphere.

Elkins, J. W.; Nance, J. D.; Moore, F. L.; Hintsa, E. J.; Dutton, G. S.; Hall, B. D.; Mondeel, D. J.; Montzka, S. A.; Hurst, D. F.; Oltmans, S. J.; Gao, R.; Fahey, D. W.; Wofsy, S. C.

2012-12-01

22

Greenhouse gases, radiative forcing, global warming potential and waste management--an introduction.  

PubMed

Management of post-consumer solid waste contributes to emission of greenhouse gases (GHGs) representing about 3% of global anthropogenic GHG emissions. Most GHG reporting initiatives around the world utilize two metrics proposed by the Intergovernmental Panel on Climate Change (IPCC): radiative forcing (RF) and global warming potential (GWP). This paper provides a general introduction of the factors that define a GHG and explains the scientific background for estimating RF and GWP, thereby exposing the lay reader to a brief overview of the methods for calculating the effects of GHGs on climate change. An objective of this paper is to increase awareness that the GWP of GHGs has been re-adjusted as the concentration and relative proportion of these GHGs has changed with time (e.g., the GWP of methane has changed from 21 to 25 CO(2)-eq). Improved understanding of the indirect effects of GHGs has also led to a modification in the methodology for calculating GWP. Following a presentation of theory behind GHG, RF and GWP concepts, the paper briefly describes the most important GHG sources and sinks in the context of the waste management industry. The paper serves as a primer for more detailed research publications presented in this special issue of Waste Management & Research providing a technology-based assessment of quantitative GHG emissions from different waste management technologies. PMID:19748948

Scheutz, Charlotte; Kjeldsen, Peter; Gentil, Emmanuel

2009-11-01

23

Interconversion of biologically important carboxylic acids by radiation  

NASA Technical Reports Server (NTRS)

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.

Negron-Mendoza, A.; Ponnamperuma, C.

1978-01-01

24

Study of multi-dimensional radiative energy transfer in molecular gases  

NASA Technical Reports Server (NTRS)

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.

Liu, Jiwen; Tiwari, S. N.

1993-01-01

25

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

26

Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB): An overview  

NASA Astrophysics Data System (ADS)

During March-May 2006, an extensive, multi-institution, multi-instrument, and multi-platform integrated field experiment ‘Integrated Campaign for Aerosols, gases and Radiation Budget’ (ICARB) was carried out under the Geosphere Biosphere Programme of the Indian Space Research Organization (ISRO-GBP). The objective of this largest and most exhaustive field campaign, ever conducted in the Indian region, was to characterize the physico-chemical properties and radiative effects of atmospheric aerosols and trace gases over the Indian landmass and the adjoining oceanic regions of the Arabian Sea, northern Indian Ocean, and Bay of Bengal through intensive, simultaneous observations. A network of ground-based observatories (over the mainland and islands), a dedicated ship cruise over the oceanic regions using a fully equipped research vessel, the Sagar Kanya, and altitude profiling over selected regions using an instrumented aircraft and balloonsondes formed the three segments of this integrated experiment, which were carried out in tandem. This paper presents an overview of the ICARB field experiment, the database generated, and some of its interesting outcomes though these are preliminary in nature. The ICARB has revealed significant spatio-temporal heterogeneity in most of the aerosol characteristics both over land and ocean. Observed aerosol loading and optical depths were comparable to or in certain regions, a little lower than those reported in some of the earlier campaigns for these regions. The preliminary results indicate: low (< 0.2) aerosol optical depths (AOD) over most part of the Arabian Sea, except two pockets; one off Mangalore and the other, less intense, in the central Arabian Sea at ˜18°N latitude

Moorthy, K. Krishna; Satheesh, S. K.; Babu, S. Suresh; Dutt, C. B. S.

2008-07-01

27

Diurnal characteristics of surface level O3 and other important trace gases in New England  

NASA Astrophysics Data System (ADS)

Data obtained from spring 2001 to summer 2003 in New England by the Atmospheric Investigation, Regional Modeling, Analysis and Prediction (AIRMAP) program were used to document the diurnal characteristics of O3, CO2, NO, and during selected intervals hydrocarbon and oxygenated species. The diurnal cycles of O3 and oxygenated species showed a monotonic rise in mixing ratio following sunrise (replenishment) that was mirrored by nighttime removal (depletion) under the nocturnal inversion. The median depletion rate of O3 was 4.9 ppbv h-1 compared to a replenishment rate of 6.2 ppbv h-1. The significant and rapid loss of O3 at night combined with an anthropogenic hydrocarbon signature dominated by a vehicular source led us to the hypothesis that nocturnal O3 depletion represented the combined effects of dry deposition and titration by NO released from mobile sources. Nighttime removal of O3 averaged 31 ppbv (median of 27 ppbv), with ˜11 ppbv due to dry deposition and ˜20 ppbv loss by titration with NO and NO2. The seasonally averaged diurnal cycles of O3 and NO were very similar from year to year, indicating that although there was large variability in the daily levels of these species, their sources/sinks were quite consistent. Moreover, CO2 and selected hydrocarbons exhibited a diurnal cycle opposite to that of O3, with the highest mixing ratios occurring at night. The diurnal cycles of oxygenated compounds such as methanol, acetaldehyde, methyl ethyl ketone, acetone + propanal, methyl vinyl ketone + methacrolein were investigated for a 2 day time period in July 2003. Our data are among the first to illustrate the diurnal cycle of these compounds. We used these species to demonstrate the importance of vertical mixing in driving the diurnal cycle of ground level O3 in New England. Day/night ratios ranged from 2.3 for acetone + propanal to 11 for methyl vinyl ketone + methacrolein. Deposition velocities of 0.5-1 m s-1 were estimated for these species, which are significantly higher than values used in many models. Such efficient removal may have important implications for the chemical impact of these species, at least on a regional scale.

Talbot, Robert; Mao, Huiting; Sive, Barkley

2005-05-01

28

Observation-based assessment of stratospheric fractional release, lifetimes, and Ozone Depletion Potentials of ten important source gases  

NASA Astrophysics Data System (ADS)

Estimates of the recovery time of stratospheric ozone heavily rely on the exact knowledge of the processes that lead to the decomposition of the relevant halogenated source gases. Crucial parameters in this context are Fractional Release Factors (FRFs) as well as stratospheric lifetimes and Ozone Depletion Potentials (ODPs). We here present data from the analysis of air samples collected between 2009 and 2011 on board research aircraft flying in the mid- and high latitudinal stratosphere and infer the above-mentioned parameters for ten major source gases:CFCl3 (CFC-11), CF2Cl2 (CFC-12), CF2ClCFCl2(CFC-113), CCl4 (carbon tetrachloride),CH3CCl3 (methyl chloroform), CHF2Cl (HCFC-22), CH3CFCl2 (HCFC-141b), CH3CF2Cl (HCFC-142b), CF2ClBr (H-1211), and CF3Br (H-1301). The inferred correlations of their FRFs with mean ages of air reveal less decomposition as compared to previous studies for most compounds. When using the calculated set of FRFs to infer equivalent stratospheric chlorine we find a reduction of more than 20% as compared to the values inferred in the most recent Scientific Assessment of Ozone Depletion by the World Meteorological Organisation (WMO, 2011). We also note that FRFs and their correlations with mean age are not generally time-independent as often assumed. The stratospheric lifetimes were calculated relative to that of CFC-11. Within our uncertainties the inferred ratios between lifetimes agree with those between stratospheric lifetimes from recent WMO reports except for CFC-11, CFC-12 and CH3CCl3. Finally we calculate lower ODPs than WMO for six out of ten compounds with changes most pronounced for the three HCFCs. Collectively these newly calculated values may have important implications for the severity and recovery time of stratospheric ozone loss.

Laube, J. C.; Keil, A.; Bönisch, H.; Engel, A.; Röckmann, T.; Volk, C. M.; Sturges, W. T.

2012-10-01

29

Observation-based assessment of stratospheric fractional release, lifetimes, and ozone depletion potentials of ten important source gases  

NASA Astrophysics Data System (ADS)

Estimates of the recovery time of stratospheric ozone heavily rely on the exact knowledge of the processes that lead to the decomposition of the relevant halogenated source gases. Crucial parameters in this context are fractional release factors (FRFs) as well as stratospheric lifetimes and ozone depletion potentials (ODPs). We here present data from the analysis of air samples collected between 2009 and 2011 on board research aircraft flying in the mid- and high-latitude stratosphere and infer the above-mentioned parameters for ten major source gases: CFCl3 (CFC-11), CF2Cl2 (CFC-12), CF2ClCFCl2 (CFC-113), CCl4 (carbon tetrachloride), CH3CCl3 (methyl chloroform), CHF2Cl (HCFC-22), CH3CFCl2 (HCFC-141b), CH3CF2Cl (HCFC-142b), CF2ClBr (H-1211), and CF3Br (H-1301). The inferred correlations of their FRFs with mean ages of air reveal less decomposition as compared to previous studies for most compounds. When using the calculated set of FRFs to infer equivalent stratospheric chlorine, we find a reduction of more than 20% as compared to the values inferred in the most recent Scientific Assessment of Ozone Depletion by the World Meteorological Organisation (WMO, 2011). We also note that FRFs and their correlations with mean age are not generally time-independent as often assumed. The stratospheric lifetimes were calculated relative to that of CFC-11. Within our uncertainties the ratios between stratospheric lifetimes inferred here agree with the values in recent WMO reports except for CFC-11, CFC-12 and CH3CCl3. Finally, we calculate lower ODPs than recommended by WMO for six out of ten compounds, with changes most pronounced for the three HCFCs. Collectively these newly calculated values may have important implications for the severity and recovery time of stratospheric ozone loss.

Laube, J. C.; Keil, A.; Bönisch, H.; Engel, A.; Röckmann, T.; Volk, C. M.; Sturges, W. T.

2013-03-01

30

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)

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.

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

2011-09-01

31

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)

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.

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

32

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

33

Breakdown of gases by CO2-laser radiation near a metal surface in the absence of developed vaporization  

NASA Astrophysics Data System (ADS)

It is shown that optical breakdown of air and other gases near the surfaces of refractory metals can occur in the absence of developed vaporization. The concentration of metal vapors above a surface irradiated by a CO2 laser is determined. It is shown that the initial degree of the ionization of air and the absorption coefficient of laser radiation are related to the concentration of metal vapors in the air. A similarity criterion is obtained which determines the minimum surface temperature at which gas breakdown can occur. The time of breakdown development is computed.

Kovalev, A. S.; Popov, A. M.

1981-01-01

34

Greenhouse Gases  

NSDL National Science Digital Library

This is a lesson where learners engage in a radiating heat activity and an activity that measures temperature in models with and without greenhouse gases. Learners will draw conclusions about the effect of greenhouse gases on temperature and on human life and kinesthetically model the absorbing and re-radiation of heat. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes, prerequisite concepts, common misconceptions, student journal and reading. This is lesson 3 in the Astro-Venture Atmospheric Science Training Unit. The purpose of the unit is to increase students’ awareness of and interest in astrobiology and the many career opportunities that utilize science, math and technology skills. The lessons are designed for educators to use in conjunction with the Astro-Venture multimedia modules.

2012-08-03

35

Dipolar Gases -- Theory  

NASA Astrophysics Data System (ADS)

In this chapter, we briefly review some important aspects of the theory of dipolar gases, focusing on those aspects in which the physics of dipolar gases differs qualitatively from that of non-dipolar ones.

Santos, Luis

2015-09-01

36

Investigation of resonance and excimer radiation from a dielectric barrier discharge in mixtures of mercury and the rare gases  

NASA Astrophysics Data System (ADS)

The excitation of resonance and excimer radiation in mixtures of mercury and the rare gases has been investigated. The gas mixtures were excited in a dielectric barrier discharge. The emission features of such discharges which are mostly in the UV and VUV range were studied in detail. Whereas resonance radiation dominates in mixtures of mercury with He, Ne, and Ar, efficient excimer formation takes place in mixtures of mercury with Kr and Xe. All the emission features of the HgXe excimer which are expected between and around the resonance lines of mercury were found and measured. A theoretical model of HgXe excimer formation is presented. This model takes both the discharge formation and the charged particle kinetics as well as the excimer and excited species formation into account. Experimentally determined Boltzmann temperatures show a decline with mercury density as is predicted by the theory for the average electron temperature. Furthermore it is, e.g., possible to calculate the efficiency of the generation of the various species observed. Due to the geometrical flexibility and high obtainable power levels, dielectric barrier discharges are very well suited for the generation of UV radiation. Apart from well-established techniques like UV lithography, disinfection, or UV curing, also new techniques in photochemistry such as, e.g., photochemical vapor deposition, profit from these new sources.

Eliasson, B.; Gellert, B.

1990-09-01

37

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

DOEpatents

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

Kurnit, Norman A. (Santa Fe, NM)

1980-01-01

38

Acceleration of radiative transfer model calculations for the retrieval of trace gases under cloudy conditions  

NASA Astrophysics Data System (ADS)

In the independent pixel approximation (IPA), radiative transfer computations involving cloudy scenes require two separate calls to the radiative transfer model (RTM), one call for a clear sky scenario, the other for an atmosphere containing clouds. In this paper, clouds are considered as an optically homogeneous layer. We present two novel methods for RTM performance enhancement with particular application to trace gas retrievals under cloudy conditions. Both methods are based on reusing results from clear-sky RTM calculations to speed up corresponding calculations for the cloud-filled scenario.

Efremenko, Dmitry S.; Loyola, Diego G.; Spurr, Robert J. D.; Doicu, Adrian

2014-03-01

39

Greenhouse Gases  

MedlinePLUS

... are greenhouse gases? Many chemical compounds present in Earth's atmosphere behave as 'greenhouse gases'. These are gases ... direct sunlight (relative shortwave energy) to reach the Earth's surface unimpeded. As the shortwave energy (that in ...

40

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

NASA Astrophysics Data System (ADS)

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

Al-Hawat, Sh.

2008-05-01

41

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

42

Interaction of radiatively cooled plasma jets with neutral gases for laboratory astrophysics studies  

NASA Astrophysics Data System (ADS)

A supersonic (Mach˜2-3), radiatively cooled plasma jet is produced by the ablation of aluminium plasma from a radial foil, a disc subjected to a ˜1.4 MA, 250 ns current from the MAGPIE pulsed-power generator. The ablated plasma converges on axis, producing a steady and collimated jet with axial velocities reaching ˜100 km/s. The study of jet-ambient interactions is achieved by introducing a neutral gas above the foil using a fast valve with a supersonic gas nozzle. The system has flexibility to study different interaction geometries in order to vary critical dimensionless parameters for astrophysical studies. In particular the effects of radiative cooling on the working surface of the jet are strongly affected by varying the gas composition. Experimental results are compared to numerical simulations using the 3-D MHD code GORGON.

Suzuki-Vidal, F.; Lebedev, S. V.; Krishnan, M.; Skidmore, J.; Swadling, G. F.; Bocchi, M.; Harvey-Thompson, A. J.; Patankar, S.; Burdiak, G. C.; de Grouchy, P.; Pickworth, L.; Stafford, S. J. P.; Suttle, L.; Bennett, M.; Bland, S. N.; Chittenden, J. P.; Hall, G. N.; Khoory, E.; Smith, R. A.; Ciardi, A.; Frank, A.; Madden, R. E.; Wilson-Elliot, K.; Coleman, P.

2013-03-01

43

Atmospheric radiation  

SciTech Connect

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.

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

1991-01-01

44

Noble Gases  

NASA Astrophysics Data System (ADS)

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,

Podosek, F. A.

2003-12-01

45

Trends in source gases  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

46

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...

47

Manure Gases  

MedlinePLUS

... of manure. The gases of most concern are ammonia and hydrogen sulfide. Other gases of concern include ... in low areas of manure storage or accumulation. Ammonia, which is lighter than air, is found above ...

48

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

SciTech Connect

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.

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

2010-03-15

49

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

SciTech Connect

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.

McFarlane, S; Shippert, T; Mather, J

2011-06-30

50

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

PubMed

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

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

2006-06-15

51

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)

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

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

2014-12-01

52

The importance of radiative feedback for the stellar initial mass function  

NASA Astrophysics Data System (ADS)

We investigate the effect of radiative feedback on the star formation process using radiation hydrodynamical simulations. We repeat the previous hydrodynamical star cluster formation simulations of Bate et al. and Bate & Bonnell, but we use a realistic gas equation of state and radiative transfer in the flux-limited diffusion approximation rather than the original barotropic equation of state. Whereas star formation in the barotropic simulations continued unabated until the simulations stopped, we find that radiative feedback, even from low-mass stars, were essentially terminates the production of new objects within low-mass dense molecular cloud cores after roughly one local dynamical time. Radiative feedback also dramatically decreases the propensity of massive circumstellar discs to fragment and inhibits fragmentation of other dense gas (e.g. filaments) close to existing protostellar objects. These two effects decrease the numbers of protostars formed by a factor of ~4 compared with the original hydrodynamical simulations using the barotropic equation of state. In particular, whereas the original simulations produced more brown dwarfs than stars, the radiative feedback results in a ratio of stars to brown dwarfs of approximately 5:1, in much better agreement with observations. Most importantly, we find that although the characteristic stellar mass in the original calculations scaled linearly with the initial mean Jeans mass in the clouds, when radiative feedback is included the characteristic stellar mass is indistinguishable for the two calculations, regardless of the initial Jeans mass of the clouds. We thus propose that the reason the observed initial mass function appears to be universal in the local Universe is due to self-regulation of the star formation process by radiative feedback. We present an analytic argument showing how a characteristic mass may be derived that is relatively independent of initial conditions such as the cloud's density.

Bate, Matthew R.

2009-02-01

53

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

E-print Network

Zi-Wei Lin Oct 5, 2004 UAH / NASA Space Radiation Shielding Program, MS Determine Important Nuclear? Conclusions Zi-Wei Lin University of Alabama in Huntsville/ NASA Space Radiation Shielding Program, MSFC #12;Zi-Wei Lin Oct 5, 2004 UAH / NASA Space Radiation Shielding Program, MS Cucinotta/JSC Individual

Lin, Zi-wei

54

Greenhouse Gases  

MedlinePLUS

... were not for naturally occurring greenhouse gases, the earth would be too cold to support life as ... the greenhouse effect, the average temperature of the earth would be about -2°F rather than the ...

55

2D Radiative MHD Simulations of the Importance of Partial Ionization in the Chromosphere  

E-print Network

The solar chromosphere is weakly ionized and interactions between ionized particles and neutral particles likely have significant consequences for the thermodynamics of the plasma. We investigate the importance of introducing neutral particles using numerical 2.5D radiative MHD simulations obtained with the Bifrost code. The models span from the upper layers of the convection zone to the low corona, and solve the full MHD equations with non-grey and NLTE radiative transfer, and thermal conduction. The effects of partial ionization are implemented using the generalized Ohm's law. The approximations required in going from three fluids to the generalized Ohm's law are tested in our simulations. The Ohmic diffusion, the 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 VAL-C model as a basis for estimates. In addition, ...

Martinez-Sykora, Juan; Hansteen, Viggo

2012-01-01

56

Atmospheric gases  

NSDL National Science Digital Library

Which gases make up the atmosphere? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the gaseous components of the atmosphere. Students explore the main gases of the atmosphere using a pop-up pie chart. Descriptions of the gases and their percentages in the atmosphere are provided. Students read about water vapor in the atmosphere, and an animation shows a simplified process of precipitation. A pop-up window explains the effects of dust on the atmosphere, and a photograph shows how large amounts of dust in the atmosphere create the reds and oranges displayed in sunsets. Finally, ozone is introduced to students as a necessary component of human life on Earth. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

57

Control of greenhouse gases emission by radiation-induced formation of useful products. Utilization of CO 2  

NASA Astrophysics Data System (ADS)

Carbon dioxide (CO 2) is produced in enormous quantities by combustion of fossil fuels in power plants and heavy industries. It is strongly influencing the environment and the climate. However, it can be separated from the exhaust gases and utilized as row material for making value-added products by irradiation. Results of experiments in laboratory scale showed, e.g. that amino acids and short chain proteins can be produced by carboxylation of amines, whereas salicylic acid results from phenol and malonic acid formation is observed from acetic acid. The yield dependence from various experimental factors as well as the reaction mechanisms of the studied systems are discussed and an outlook of future developments is given.

Getoff, Nikola

2006-04-01

58

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

SciTech Connect

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

Milas, Luka [Department of Experimental Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)]. E-mail: lmilas@mdanderson.org; Fang, F.-M. [Department of Experimental Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Mason, Kathy A. [Department of Experimental Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Valdecanas, David B.S. [Department of Experimental Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Hunter, Nancy [Department of Experimental Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Koto, Masashi [Department of Experimental Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Ang, K. Kian [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)

2007-02-01

59

Important Role of Autophagy in Endothelial Cell Response to Ionizing Radiation  

PubMed Central

Objectives Vasculature damage is an important contributor to the side-effects of radiotherapy. The aim of this study is to provide insights into the radiobiology of the autophagic response of endothelial cells. Methods and Materials Human umbilical vascular endothelial cells (HUVEC) were exposed to 2 Gy of ionizing radiation (IR) and studied using confocal microscopy and western blot analysis, at 4 and 8 days post-irradiation. The role of autophagy flux in HUVEC radio-sensitivity was also examined. Results IR-induced accumulation of LC3A+, LC3B+ and p62 cytoplasmic vacuoles, while in double immunostaining with lysosomal markers (LAMP2a and CathepsinD) repression of the autophagolysosomal flux was evident. Autophagy-related proteins (ATF4, HIF1?., HIF2?, Beclin1) were, however, induced excluding an eventual repressive effect of radiation on autophagy initiating protein expression. Exposure of HUVEC to SMER28, an mTOR-independent inducer of autophagy, enhanced proLC3 and LC3A, B-I protein expression and accelerated the autophagic flux. Pre-treatment of HUVEC with SMER28 protected against the blockage of autophagic flux induced by IR and conferred radio-resistance. Suppression of LC3A/LC3B proteins with siRNAs resulted in radio-sensitization. Conclusions The current data provide a rationale for the development of novel radioprotection policies targeting the autophagic pathway. PMID:25010689

Kalamida, Dimitra; Karagounis, Ilias V.; Giatromanolaki, Alexandra; Koukourakis, Michael I.

2014-01-01

60

Measurement of Selected Organic Trace Gases During TRACE-P  

NASA Technical Reports Server (NTRS)

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.

Atlas, Elliot

2004-01-01

61

Thermal efficiency of the principal greenhouse gases  

NASA Astrophysics Data System (ADS)

Atmospheric gases are ranked according to the efficiency with which they absorb and radiate longwave radiation. The open international HITRAN database of gaseous absorption lines of high resolution together with inverse Fourier transform were used. The autocorrelation functions of the total dipole moment of the basic greenhouse gases molecules such as H2O, CO2, O3, N2O, and CH4 were obtained. Absorption coefficient spectra and emission power spectra of infrared radiation of these gases were calculated. Analysis of the emissive ability of all gases under consideration was carried out. Compared to CO2, all the gases under investigation have more effective emission except ozone. An efficiency criterion of IR absorption and emission is defined and is calculated for each studied gas, and the gases are ranked accordingly as follows (from strong to weak): H2O, CH4, CO2, N2O, and O3.

Y. Galashev, A.; R. Rakhmanova, O.

2015-01-01

62

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

NASA Technical Reports Server (NTRS)

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.

Lin, Zi-wei

2004-01-01

63

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

NASA Technical Reports Server (NTRS)

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.

Lin, Zi-Wei

2004-01-01

64

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

NASA Technical Reports Server (NTRS)

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.

Lin, Zi-Wei

2004-01-01

65

Theoretical studies of spectroscopic problems of importance for atmospheric radiation measurements  

NASA Technical Reports Server (NTRS)

Many of the instruments used to deduce the physical parameters of the Earth's atmosphere necessary for climate studies or for pollution monitoring (for instance, temperature versus pressure or number densities of trace molecules) rely on the existence of accurate spectroscopic data and an understanding of the physical processes responsible for the absorption or emission of radiation. During the summer, research was either continued or begun on three distinct problems: (1) an improved theoretical framework for the calculation of the far-wing absorption of allowed spectral lines; (2) a refinement of the calculation of the collision-induced fundamental spectrum of N2; and (3) an investigation of possible line-mixing effects in the fundamental spectrum of CH4. Progress in these three areas is summarized below. During the past few years, we have developed a theoretical framework for the calculation of the absorption of radiation by the far wings of spectral lines. Such absorption due to water vapor plays a crucial role in the greenhouse effect as well as limiting the retrieval of temperature profiles from satellite data. Several improvements in the theory have been made and the results are being prepared for publication. Last year we published results for the theoretical calculation of the absorption of radiation due to the dipoles induced during binary collisions of N2 molecules using independently measured molecular parameters; the results were in reasonable agreement with experimental data. However, recent measurements have revealed new fine structure that has been attributed to line-mixing effects. We do not think that this is correct, rather that the structure results from short-range anisotropic dipoles. We are in the process of including this refinement in our theoretical calculation in order to compare with the new experimental data. Subtle changes in the spectra of CH4 measured by researchers at Langley have also been attributed to line-mixing effects. By analyzing the same spectral lines we have attempted to verify or rule out possible line-mixing mechanisms. Due to the complexity and richness of the spectrum of this highly symmetric molecule, as well as the small magnitude of the effects, a detailed first-principle calculation of the mixing is a difficult problem. Before such a program is undertaken it is important to glean as much information as possible concerning the possible mechanisms by a systematic analysis of the existing data.

Tipping, Richard H.

1994-01-01

66

Direct and ozone-mediated forcing of the Southern Annular Mode by greenhouse gases  

NASA Astrophysics Data System (ADS)

We assess the roles of long-lived greenhouse gases and ozone depletion in driving meridional surface pressure gradients in the southern extratropics; these gradients are a defining feature of the Southern Annular Mode. Stratospheric ozone depletion is thought to have caused a strengthening of this mode during summer, with increasing long-lived greenhouse gases playing a secondary role. Using a coupled atmosphere-ocean chemistry-climate model, we show that there is cancelation between the direct, radiative effect of increasing greenhouse gases by the also substantial indirect—chemical and dynamical—feedbacks that greenhouse gases have via their impact on ozone. This sensitivity of the mode to greenhouse gas-induced ozone changes suggests that a consistent implementation of ozone changes due to long-lived greenhouse gases in climate models benefits the simulation of this important aspect of Southern Hemisphere climate.

Morgenstern, Olaf; Zeng, Guang; Dean, Sam M.; Joshi, Manoj; Abraham, N. Luke; Osprey, Annette

2014-12-01

67

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

SciTech Connect

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

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

1993-12-01

68

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)

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.

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

2014-05-01

69

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

SciTech Connect

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.

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

70

Two-dimensional Radiative Magnetohydrodynamic Simulations of the Importance of Partial Ionization in the Chromosphere  

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

71

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)

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.

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

1986-01-01

72

An important step forward in continuous spectroscopic imaging of ionising radiations using ASICs  

Microsoft Academic Search

Characterization results are given for an original ASIC allowing continuous acquisition of ionising radiation images in spectroscopic mode. Ionising radiation imaging in general and spectroscopic imaging in particular must primarily be guided by the attempt to decrease statistical noise, which requires detection systems designed to allow very high counting rates. Any source of dead time must therefore be avoided. Thus,

P. Fessler; J. Coffin; H. Eberlé; C de Raad Iseli; B. Hilt; D. Huss; F. Krummenacher; J. R Lutz; G. Prévot; A. Renouprez; M. H Sigward; B. Schwaller; C. Voltolini

1999-01-01

73

Ecological importance of ambient solar ultraviolet radiation to a sub-arctic heath community  

Microsoft Academic Search

While there is considerable knowledge of the effects of enhanced levelsof ultraviolet radiation (UV) on plant species, much less is known of theimportance of ambient levels of solar UV, particularly on natural plantcommunities. Effects of ambient solar UV radiation on a natural sub-Arcticheathcommunity were investigated in a three year UV exclusion experiment in northernSweden (68° N). UV transparent and UV

Gareth K. Phoenix; Dylan Gwynn-Jones; John A. Lee; Terry V. Callaghan

2003-01-01

74

Feshbach resonances in ultracold gases  

SciTech Connect

Feshbach resonances are the essential tool to control the interaction between atoms in ultracold quantum gases. They have found numerous experimental applications, opening up the way to important breakthroughs. This review broadly covers the phenomenon of Feshbach resonances in ultracold gases and their main applications. This includes the theoretical background and models for the description of Feshbach resonances, the experimental methods to find and characterize the resonances, a discussion of the main properties of resonances in various atomic species and mixed atomic species systems, and an overview of key experiments with atomic Bose-Einstein condensates, degenerate Fermi gases, and ultracold molecules.

Chin Cheng; Grimm, Rudolf; Julienne, Paul; Tiesinga, Eite [Department of Physics and James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States); Center for Quantum Physics and Institute of Experimental Physics, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck (Austria) and Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Otto-Hittmair-Platz 1, 6020 Innsbruck (Austria); Joint Quantum Institute, National Institute of Standards and Technology and University of Maryland, 100 Bureau Drive, Gaithersburg, Maryland 20899-8423 (United States)

2010-04-15

75

Agricultural ecosystem effects on trace gases and global climate change  

SciTech Connect

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.

Not Available

1993-01-01

76

Gravity versus radiation models: on the importance of scale and heterogeneity in commuting flows.  

PubMed

We test the recently introduced radiation model against the gravity model for the system composed of England and Wales, both for commuting patterns and for public transportation flows. The analysis is performed both at macroscopic scales, i.e., at the national scale, and at microscopic scales, i.e., at the city level. It is shown that the thermodynamic limit assumption for the original radiation model significantly underestimates the commuting flows for large cities. We then generalize the radiation model, introducing the correct normalization factor for finite systems. We show that even if the gravity model has a better overall performance the parameter-free radiation model gives competitive results, especially for large scales. PMID:24032888

Masucci, A Paolo; Serras, Joan; Johansson, Anders; Batty, Michael

2013-08-01

77

Greenhouse Gases  

NSDL National Science Digital Library

Explore how the Earth's atmosphere affects the energy balance between incoming and outgoing radiation. Using an interactive model, adjust realistic parameters such as how many clouds are present or how much carbon dioxide is in the air, and watch how these factors affect the global temperature.

2012-07-19

78

Identification of aerosol type over the Arabian Sea in the premonsoon season during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)  

NASA Astrophysics Data System (ADS)

A discrimination of the different aerosol types over the Arabian Sea (AS) during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB-06) is made using values of aerosol optical depth (AOD) at 500 nm (AOD500) and Ångström exponent (?) in the spectral band 340-1020 nm (?340-1020). For this purpose, appropriate thresholds for AOD500 and ?340-1020 are applied. It is shown that a single aerosol type in a given location over the AS can exist only under specific conditions while the presence of mixed aerosols is the usual situation. Analysis indicates that the dominant aerosol types change significantly in the different regions (coastal, middle, and far) of AS. Thus the urban/industrial aerosols are mainly observed in coastal AS, the desert dust particles occur in the middle and northern AS, while clear maritime conditions mainly occur in far AS. Spectral AOD and Ångström exponent data were analyzed to obtain information about the adequacy of the simple use of the Ångström exponent and spectral variation of ? for characterizing the aerosols. Using the least squares method, ? is calculated in the spectral interval 340-1020 nm along with the coefficients a1 and a2 of the second-order polynomial fit to the plotted logarithm of AOD versus the logarithm of wavelength. The results show that the spectral curvature can effectively be used as a tool for their discrimination, since the fine mode aerosols exhibit negative curvature, while the coarse mode particles exhibit positive curvature. The correlation between the coefficients a1 and a2 with the Ångström exponent, and the atmospheric turbidity, is further investigated.

Kalapureddy, M. C. R.; Kaskaoutis, D. G.; Ernest Raj, P.; Devara, P. C. S.; Kambezidis, H. D.; Kosmopoulos, P. G.; Nastos, P. T.

2009-09-01

79

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

PubMed Central

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

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

2010-01-01

80

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

PubMed

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

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

2010-11-01

81

IONIZING RADIATION IN ABDOMINAL COMPUTED TOMOGRAPHY: UNINDICATED MULTIPHASE SCANS ARE AN IMPORTANT SOURCE OF MEDICALLY UNNECESSARY EXPOSURE  

PubMed Central

Introduction Computed tomography (CT) radiation exposure has come under increasing scrutiny due to dramatically increased utilization. Multiphase CT studies (repeated scanning before and after contrast injection) are potentially important, overlooked source of medically unnecessary radiation due to the dose-multiplier effect of extra phases. The purpose of this study is to determine the frequency of unindicated multiphase scanning and resultant excess radiation exposure in a sample referral population. Methods This study was IRB approved and HIPAA compliant. Abdomen/pelvis CT exams (n=500) performed at outside institutions submitted for tertiary interpretation were retrospectively reviewed for 1) appropriateness of each phase based on clinical indication and American College of Radiology (ACR) Appropriateness Criteria, and 2) per phase and total radiation effective dose. Results A total of 978 phases were performed in 500 patients, 52.8% (264/500) received phases that were not supported by ACR criteria. Overall, 35.8% (350/978) of phases were unindicated, most commonly being delayed imaging (272/350). The mean overall total radiation effective dose per patient was 25.8 mSv (95% CI 24.2, 27.5 mSv). Mean effective dose for unindicated phases was 13.1 (12.3, 14.0) mSv, resulting in a mean excess effective dose of 16.8 (15.5, 18.3) mSv per patient. Unindicated radiation comprised 33.3% of the total radiation effective dose in this population. Radiation effective doses exceeding 50 mSv were found in 21.2% (106/500) of patients. Discussion The results of this study suggest that a large proportion of patients undergoing abdominal/pelvic CT scanning receive unindicated additional phases that add substantial excess radiation dose with no associated clinical benefit. PMID:22051457

Guite, Kristie M.; Hinshaw, J. Louis; Ranallo, Frank N.; Lindstrom, Mary J.; Lee, Fred T.

2014-01-01

82

Separation of polar gases from nonpolar gases  

Microsoft Academic Search

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol

S. Kulprathipanja; S. S. Kulkarni

1986-01-01

83

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

E-print Network

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.

Weihsueh A. Chiu; B. T. Draine

1998-03-18

84

Determination of Important Nuclear Fragmentation Processes for Human Space Radiation Protection  

NASA Technical Reports Server (NTRS)

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.

Lin, Zi-Wei

2007-01-01

85

GREENHOUSE GASES AND GLOBAL WARMING  

Microsoft Academic Search

Summary Global warming is an important environmental issue which is rapidly becoming a part of popular culture. This paper provides an account of the science associated with this important issue. Historical evidence for past climate change is discussed. The difference between weather and climate is highlighted. The physics of the greenhouse effect and the concept of greenhouse gases are presented.

Timothy J. Wallington; Jayaraman Srinivasan; Ole John Nielsen; Ellie J. Highwood

86

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

SciTech Connect

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

Schumacher, Courtney

2012-12-13

87

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

NASA Astrophysics Data System (ADS)

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

Hill, Mark

2012-07-01

88

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

NASA Astrophysics Data System (ADS)

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.

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

2006-12-01

89

Electrical breakdown of gases  

Microsoft Academic Search

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)

J. M. Meek; J. D. Craggs

1978-01-01

90

Aerosol chemical and radiative properties in the tropical Atlantic trade winds: The importance of African mineral dust  

NASA Astrophysics Data System (ADS)

This dissertation presents results relevant to aerosol radiative forcing. The focus of this dissertation is the role of mineral dust in atmospheric radiative processes over the tropical Atlantic Ocean. The aerosol mass and light scattering data concurrently measured over the tropical North Atlantic ocean yield a dust mass scattering efficiency of 0.77 m2/g, about a quarter of that measured for non-sea-salt sulfate (nss SO4=) in the North Atlantic marine boundary layer. Because of the high concentration of mineral dust relative to nss SO4= over the tropical North Atlantic, the total scattering by mineral dust is about four times that by nss SO4 = aerosol in this region. On an annual basis, aerosol optical depth is apportioned to: mineral dust 71%, nss- SO4 = 16% and sea salt 13%. The coarse-particle fraction (CPF) (aerodynamic diameter > 1 ?m) of nss SO4= varied from about 21% to 73%, with the highest CPF values associated with African dust events. The CPF nss SO 4= was believed to be a result of the heterogeneous reactions of SO2 (presumably from European sources) with dust particles suspended in the air over North Africa. This study provides the first direct evidence that confirms the importance of dust in sulfate production and resulting the coarse particle sulfate in the tropical Atlantic Ocean region. An important implication is that dust particles may reduce the effectiveness of sulfate aerosol as a radiative forcing agent in many regions where dust events are frequent and where dust concentrations are high. The aerosol scattering coefficient (ASC) measured during this experiment increased by a factor of 1.13 to 1.69 when RH was increased from about 40% to 80%. Through chemical apportioning of ASC, the HGF for sea-salt was found to be 1.8 +/- 0.2, while that of mineral dust was close to unity. This study shows that climate studies must consider the effect of mineral dust not only because of its direct effects on the radiation balance but also because of its effects on the radiative properties of other species that are present in the same air mass.

Li-Jones, Xu

91

The importance of tissue segmentation for dose calculations for kilovoltage radiation therapy  

PubMed Central

Purpose: The aim of this work was to evaluate the effect of tissue segmentation on the accuracy of Monte Carlo (MC) dose calculations for kilovoltage radiation therapy, which are commonly used in preclinical radiotherapy studies and are also being revisited as a clinical treatment modality. The feasibility of tissue segmentation routinely done on the basis of differences in tissue mass densities was studied and a new segmentation scheme based on differences in effective atomic numbers was developed.Methods: MC dose calculations in a cylindrical mouse phantom with small cylindrical inhomogeneities consisting of 34 ICRU-44 tissues were performed using the EGSnrc?BEAMnrc and DOSXYZnrc codes. The dose to tissue was calculated for five different kilovoltage beams currently used in small animal radiotherapy: a microCT 120 kV beam, two 225 kV beams filtered with either 4 mm of Al or 0.5 mm of Cu, a heavily filtered 320 kV beam, and a 192Ir beam. The mean doses to the 34 ICRU-44 tissues as a function of tissue mass density and effective atomic number and beam energy were studied. A treatment plan for an orthotopic lung tumor model was created, and the dose distribution was calculated for three tissue segmentation schemes using 4, 8, and 39 tissue bins to assess the significance of the simulation results for kilovoltage radiotherapy.Results: In our model, incorrect assignment of adipose tissue to muscle caused dose calculation differences of 27%, 13%, and 7% for the 120 kV beam and the 225 kV beams filtered with 4 mm Al and 0.5 mm Cu, respectively. For the heavily filtered 320 kV beam and a 192Ir source, potential dose calculation differences due to tissue mis-assignment were below 4%. There was no clear relationship between the dose to tissue and its mass density for x-ray beams generated by tube potentials equal or less than 225 kV. A second order polynomial fit approximated well the absorbed dose to tissue as a function of effective atomic number for these beams. In the mouse study, the 120 kV beam dose to bone was overestimated by 100% and underestimated by 10% for the 4 and 8-tissue segmentation schemes compared to the 39-tissue segmentation scheme, respectively. Dose to adipose tissue was overestimated by 30% and underestimated by 10%, respectively. In general, organ at risk (OAR) doses were overestimated in the 4-tissue and the 8-tissue segmentation schemes compared to the 39-tissue segmentation.Conclusions: Tissue segmentation was shown to be a key parameter for dose calculations with kilovoltage beams used in small animal radiotherapy when an x-ray tube with a potential ?225 kV is used as a source. A new tissue segmentation scheme with 39 tissues based on effective number differences derived from mass density differences has been implemented. PMID:21815377

Bazalova, Magdalena; Graves, Edward E.

2011-01-01

92

Separation of polar gases from nonpolar gases  

DOEpatents

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.

Kulprathipanja, Santi (Hoffman Estates, IL)

1986-01-01

93

Separation of polar gases from nonpolar gases  

DOEpatents

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.

Kulprathipanja, S.

1986-08-19

94

Separation of polar gases from nonpolar gases  

DOEpatents

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

Kulprathipanja, S.; Kulkarni, S.S.

1986-08-26

95

Separation of polar gases from nonpolar gases  

DOEpatents

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

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

1986-01-01

96

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

EPA Science Inventory

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

97

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

SciTech Connect

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

Manickavasagam, S.; Menguec, M.P.

1994-09-01

98

The origin and radiation of Macaronesian beetles breeding in Euphorbia: the relative importance of multiple data partitions and population sampling.  

PubMed

Species-level phylogenies derived from many independent character sources and wide geographical sampling provide a powerful tool in assessing the importance of various factors associated with cladogenesis. In this study, we explore the relative importance of insular isolation and host plant switching in the diversification of a group of bark beetles (Curculionidae: Scolytinae) feeding and breeding in woody Euphor biaspurges. All species in the genus Aphanarthrumare each associated with only one species group of Euphorbia(succulents or one of three different arborescent groups), and the majority of species are endemic to one or several of the Macaronesian Islands. Hence, putative mechanisms of speciation could be assessed by identifying pairs of sister species in a phylogenetic analysis. We used DNA sequences from two nuclear and two mitochondrial genes, and morphological characters, to reconstruct the genealogical relationships among 92 individuals of 25 species and subspecies of Aphanarthrumand related genera. A stable tree topology was highly dependent on multiple character sources, but much less so on wide population sampling. However, multiple samples per species demonstrated one case of species paraphyly, as well as deep coalescence among three putative subspecies pairs. The phylogenetic analyses consistently placed the arborescent breeding and West African--Lanzarote-distributed species A. armatumin the most basal position in Aphanarthrum, rendering this genus paraphyletic with respect to Coleobothrus. Two major radiations followed, one predominantly African lineage of succulent feeding species, and one island radiation associated with arborescent host plants. Sister comparisons showed that most recent divergences occurred in allopatry on closely related hosts, with subsequent expansions obscuring more ancient events. Only 6 out of 24 cladogenetic events were associated with host switching, rendering geographical factors more important in recent diversification. PMID:15545251

Jordal, Bjarte H; Hewitt, Godfrey M

2004-10-01

99

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

SciTech Connect

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.

Not Available

1993-11-10

100

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

PubMed Central

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

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

2014-01-01

101

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

SciTech Connect

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

Wigley, T.M.L.

1993-01-01

102

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

NASA Astrophysics Data System (ADS)

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 the alkali atoms; which enables 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 defection spectroscopy indicates large relative temperature changes down to and even below room temperature starting from an initial cell temperature near 700K. 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.

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

2014-02-01

103

Transport of Trace Gases  

NASA Technical Reports Server (NTRS)

Trace gases measurements are used to diagnose both the chemistry and transport of the atmosphere. These lectures emphasize the interpretation of trace gases measurements and techniques used to untangle chemistry and transport effects. I will discuss PV transform, trajectory techniques, and age-of-air as far as the circulation of the stratosphere.

Schoeberl, Mark R.

2005-01-01

104

ANALYSIS OF PROTOCOL GASES  

EPA Science Inventory

In 1992, EPA's Atmospheric Research and Exposure Assessment Laboratory initiated a nationwide QA program on the suppliers of EPA Protocol Gases. he program has three goals: to increase the acceptance and use of Protocol Gases by the air monitoring community, to provide a QA check...

105

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

E-print Network

-guided diagnosis and radiation therapy. For diagnosis, the fact that the patient dose committed by proton CT imaging method to perform planning and verification of proton-based radiation treatment, since proton the most appropriate imaging method to perform planning and verification of proton-based radiation

California at Santa Cruz, University of

106

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

107

Future global warming from atmospheric trace gases  

NASA Astrophysics Data System (ADS)

The effect of the continuing addition of trace gases to the atmosphere due to human activity on the future global surface temperatures is examined. The radiative properties of the atmosphere are reviewed, and the atmospheric increase in carbon dioxide, halocarbons, nitrous oxide, methane, and ozone is discusssed. Future scenarios resulting from these trends and their implications for climate change are considered.

Dickinson, R. E.; Cicerone, R. J.

1986-01-01

108

Measurements of Trace Gases Using a Tunable Diode Laser  

NASA Technical Reports Server (NTRS)

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.

Jost, Hans-Juerg

2005-01-01

109

Measurement of aerosol particles, gases and flux radiation in the Pico de Orizaba National Park, and its relationship to air pollution transport  

NASA Astrophysics Data System (ADS)

Continuous atmospheric measurements were carried out at the Pico de Orizaba National Park (PONP), Mexico, in order to evaluate the characteristics and sources of air quality. This action allowed one to identify specific threats for the effective protection of natural resources and biodiversity. Results show the presence of particles and polluted gases transported by winds from the urban zones nearby (cities of Mexico, Puebla and Tlaxcala), as well as their measurable influence on the optical properties of the park environment. Nitrogen dioxide, carbon monoxide and sulfur dioxide show a daily pattern suggesting an influence of pollution generated by anthropogenic processes. Average concentration of SO 2 was higher than recorded at the southern part of Mexico City. Ozone concentrations ranging from 0.035 to 0.06 ppm suggest residual or background ozone character. Back trajectory analysis of air parcels arriving at the site confirm pollution caused by biomass burning and mass transport from urban zones. The SO 42-/TC ratio exhibited values (0.88±0.33) similar to urban areas. Ratios BC/TC and OC/BC for PONP are similar to those reported as influenced by burning emissions of fossil fuels. Typical rural aerosols were also found at the site, and sulfate and ammonium concentrations were correlated. The most predominating mode in surface particles size distribution was at 0.32 ?m with no significant presence of coarse particles. Total carbon (OC+BC) content of fine particle mass (PM less than 1 ?m) comprised, on average, 75%. Optical properties retrieved from photometric data show intermittent influence from urban pollution. Time periods with low absorbing particles, great visibility and abundance of small particles alternating with short times with bigger particles and high turbidity indicated by the optical depth.

Márquez, C.; Castro, T.; Muhlia, A.; Moya, M.; Martínez-Arroyo, A.; Báez, A.

110

Regulating Greenhouse Gases  

NSDL National Science Digital Library

This video highlights the work of climate scientists in the Amazon who research the relationship between deforestation, construction of new dams, and increased amounts of greenhouse gases being exchanged between the biosphere and the atmosphere.

KQED

111

THE IMPORTANCE OF XUV RADIATION AS A SOLUTION TO THE P V MASS LOSS RATE DISCREPANCY IN O STARS  

SciTech Connect

A controversy has developed regarding the stellar wind mass loss rates in O stars. The current consensus is that these winds may be clumped, which implies that all previously derived mass loss rates using density-squared diagnostics are overestimated by a factor of {approx}2. However, arguments based on Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the P V resonance line doublet suggest that these rates should be smaller by another order of magnitude, provided that P V is the dominant phosphorous ion among these stars. Although a large mass loss rate reduction would have a range of undesirable consequences, it does provide a straightforward explanation of the unexpected symmetric and un-shifted X-ray emission-line profiles observed in high-energy resolution spectra. But acceptance of such a large reduction then leads to a contradiction with an important observed X-ray property: the correlation between He-like ion source radii and their equivalent X-ray continuum optical depth unity radii. Here we examine the phosphorous ionization balance since the P V fractional abundance, q (P V), is fundamental to understanding the magnitude of this mass loss reduction. We find that strong emission line radiation in the XUV energy band (defined here as 54 to 124 eV) can significantly reduce q (P V). Furthermore, owing to the unique energy distribution of these XUV lines, there is a negligible impact on the S V fractional abundance (a key component in the FUSE mass loss argument). We conclude that large reductions in O star mass loss rates are not required, and the X-ray optical depth unity relation remains valid.

Waldron, W. L. [Eureka Scientific Inc., 2452 Delmer Street, Oakland, CA 94602 (United States); Cassinelli, J. P. [Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53711 (United States)], E-mail: wwaldron@satx.rr.com, E-mail: cassinelli@astro.wisc.edu

2010-03-01

112

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

PubMed Central

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

Gwynn-Jones, Dylan

2013-01-01

113

Noble gases in ureilites released by crushing  

NASA Astrophysics Data System (ADS)

Noble gases in two ureilites, Kenna and Allan Hills (ALH) 78019, were measured with two extraction methods: mechanical crushing in a vacuum and heating. Large amounts of noble gases were released by crushing, up to 26.5% of 132Xe from ALH 78019 relative to the bulk concentration. Isotopic ratios of the crush-released Ne of ALH 78019 resemble those of the trapped Ne components determined for some ureilites or terrestrial atmosphere, while the crush-released He and Ne from Kenna are mostly cosmogenic. The crush-released Xe of ALH 78019 and Kenna is similar in isotopic composition to Q gas, which indicates that the crush-released noble gases are indigenous and not caused by contamination from terrestrial atmosphere. In contrast to the similarities in isotopic composition with the bulk samples, light elements in the crush-released noble gases are depleted relative to Xe and distinct from those of each bulk sample. This depletion is prominent especially in the 20Ne/132Xe ratio of ALH 78019 and the 36Ar/132Xe ratio of Kenna. The values of measured 3He/ 21Ne for the gases released by crushing are significantly higher than those for heating-released gases. This suggests that host phases of the crush-released gases might be carbonaceous because cosmogenic Ne is produced mainly from elements with a mass number larger than Ne. Based on our optical microscopic observation, tabular-foliated graphite is the major carbon mineral in ALH 78019, while Kenna contains abundant polycrystalline graphite aggregates and diamonds along with minor foliated graphite. There are many inclusions at the edge and within the interior of olivine grains that are reduced by carbonaceous material. Gaps can be seen at the boundary between carbonaceous material and silicates. Considering these petrologic and noble gas features, we infer that possible host phases of crush-released noble gases are graphite, inclusions in reduction rims, and gaps between carbonaceous materials and silicates. The elemental ratios of noble gases released by crushing can be explained by fractionation, assuming that the starting noble gas composition is the same as that of amorphous carbon in ALH 78019. The crush-released noble gases are the minor part of trapped noble gases in ureilites but could be an important clue to the thermal history of the ureilite parent body. Further investigation is needed to identify the host phases of the crush-released noble gases.

Okazaki, R.; Nakamura, T.; Takaoka, N.; Nagao, K.

2003-05-01

114

The importance of radiation doses to the penile bulb vs. crura in the development of postbrachytherapy erectile dysfunction  

Microsoft Academic Search

Purpose: Recent studies have implicated the proximal penis as a potential site-specific structure for radiation-related erectile dysfunction (ED). In this study, we evaluated by means of a validated patient-administered questionnaire whether radiation doses to the bulb of the penis and\\/or the proximal corporeal bodies were predictive for the development of brachytherapy-induced ED.Methods and Materials: Thirty patients who underwent permanent prostate

Gregory S Merrick; Wayne M Butler; Kent E Wallner; Jonathan H Lief; Richard L Anderson; Benjamin J Smeiles; Robert W Galbreath; Mark L Benson

2002-01-01

115

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

E-print Network

@mil.sunysb.edu). . imaging is about 10 times higher than that of a conventional 3D-CT study. Radiation dose during 4D-dCT studies. 4D-dCT acquires multiple repeated measurements from the same patient. Therefore, the radiation dose during a 4D-dCT procedure is much higher than a routine 3D CT study. Low-dose scans for 4D-dCT

116

Thermodynamic models of the chemistry of lunar volcanic gases  

NASA Technical Reports Server (NTRS)

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.

Fegley, Bruce, Jr.

1991-01-01

117

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

PubMed

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

Tomita, Masanori; Maeda, Munetoshi

2014-10-31

118

Gases: Characteristics and Properties  

NSDL National Science Digital Library

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.

Brieske, Joel A.

119

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

PubMed

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

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

1998-01-01

120

Gases in Tektite Bubbles.  

PubMed

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

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

1962-07-20

121

Glass Membrane For Controlled Diffusion Of Gases  

DOEpatents

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.

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

2001-05-15

122

Line-driven Disk Winds in Active Galactic Nuclei: The Critical Importance of Ionization and Radiative Transfer  

E-print Network

Accretion disk winds are thought to produce many of the characteristic features seen in the spectra of active galactic nuclei (AGN) 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 & Kallman (2004). 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 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 wind no longer produ...

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

2014-01-01

123

Important Role of Catalase in the Cellular Response of the Budding Yeast Saccharomyces cerevisiae Exposed to Ionizing Radiation.  

PubMed

Ionizing radiation indirectly causes oxidative stress in cells via reactive oxygen species (ROS), such as hydroxyl radicals (OH(-)) generated by the radiolysis of water. We investigated how the catalase function was affected by ionizing radiation and analyzed the phenotype of mutants with a disrupted catalase gene in Saccharomyces cerevisiae exposed to radiation. The wild-type yeast strain and isogenic mutants with disrupted catalase genes were exposed to various doses of (60)Co gamma-rays. There was no difference between the wild-type strain and the cta1 disruption mutant following exposure to gamma-ray irradiation. In contrast, there was a significant decrease in the ctt1 disruption mutant, suggesting that this strain exhibited decreased survival on gamma-ray exposure compared with other strains. In all three strains, stationary phase cells were more tolerant to the exposure of gamma-rays than exponential phase cells, whereas the catalase activity in the wild-type strain and cta1 disruption mutant was higher in the stationary phase than in the exponential phase. These data suggest a correlation between catalase activity and survival following gamma-ray exposure. However, this correlation was not clear in the ctt1 disruption mutant, suggesting that other factors are involved in the tolerance to ROS induced by irradiation. PMID:25416226

Nishimoto, Takuto; Furuta, Masakazu; Kataoka, Michihiko; Kishida, Masao

2015-03-01

124

Importance of Accurate Liquid Water Path for Estimation of Solar Radiation in Warm Boundary Layer Clouds: An Observational Study  

SciTech Connect

A one-year observational study of overcast boundary layer stratus at the U.S. Department of Energy Atmospheric Radiation Measurement Program Southern Great Plains site illustrates that surface radiation is primarily sensitive to cloud liquid water path, with cloud drop effective radius having a secondary influence. The mean, median and standard deviation of cloud liquid water path and cloud drop effective radius for the dataset are 0.120 mm, 0.101 mm, 0.108 mm, and 7.38 {micro}m, 7.13 {micro}m, 2.39 {micro}m, respectively. Radiative transfer calculations demonstrate that cloud optical depth and cloud normalized forcing are respectively three and six times as sensitive to liquid water path variations as they are to effective radius variations, when the observed ranges of each of those variables is considered. Overall, there is a 79% correlation between observed and computed surface fluxes when using a fixed effective radius of 7.5 {micro}m and observed liquid water paths in the calculations. One conclusion from this study is that measurement of the indirect aerosol effect will be problematic at the site, as variations in cloud liquid water path will most likely mask effects of variations in particle size.

Sengupta, Manajit; Clothiaux, Eugene E.; Ackerman, Thomas P.; Kato, Seiji; Min, Qilong

2003-09-15

125

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...

126

16 Rangelands educing concentrations of greenhouse gases  

E-print Network

sequestration or decrease carbon loss will be especially important. The Terrestrial Carbon Cycle Prior the current amount of carbon being stored in an area. In the terrestrial carbon cycle (Supplemental Material and the atmosphere. Carbon dioxide (CO2 ) is one of the primary anthropogenic greenhouse gases. Reductions

127

Radiation  

Cancer.gov

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

128

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,...

129

Line-driven Disk Winds in Active Galactic Nuclei: The Critical Importance of Ionization and Radiative Transfer  

NASA Astrophysics Data System (ADS)

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 & 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.

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

2014-07-01

130

Advanced Global Atmospheric Gases Experiment (AGAGE)  

NASA Technical Reports Server (NTRS)

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.

Prinn, Ronald G.

2001-01-01

131

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)

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.

Girard, Eric; Sokhandan Asl, Niloofar

2014-01-01

132

Greenhouse Gases Exposed  

NSDL National Science Digital Library

In this activity, students learn about the relationship between greenhouse gases and global warming through a simple teacher demo or hands-on lab activity. Everyday materials are used: beakers, baking soda, vinegar, candle, thermometers, heat source such as a goose-necked lamp, etc. Students shine a light onto three thermometers: a control, an upside down beaker w/ a thermometer and air, and a beaker in which CO2 had been poured.

Victoria Babcock

133

Supercontinuum generation in gases  

Microsoft Academic Search

Supercontinua extending from the ultraviolet to the infrared are observed from high-pressure (1-40 atm) Ar, Kr, Xe, H2, or CO2 illuminated with 2-psec or 70-fsec, 0.6-micron pulses with an energy of less than about 500 micro J. The blue spectral component is shown to display a nearly universal behavior for all gases and pulse durations. Although the maximum intensity of

P. B. Corkum; Claude Rolland; T. Srinivasan-Rao

1986-01-01

134

Greenhouse gases: What is their role in climate change  

SciTech Connect

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.

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

1990-12-01

135

Laser Induced Nonlinear Effects in Molecular Gases  

NASA Astrophysics Data System (ADS)

This dissertation is a study of both theoretical and experimental aspects of various non-linear effects, stimulated Raman and Brillouin scattering processes, four -wave mixing, multi-photon absorption leading to ionization, dissociation, and excitation and optical breakdown in molecular gases such as H_2, HD, D _2 and CH_4 induced by a third harmonic of a Nd:YAG laser. The most important third order effect namely, the stimulated Raman scattering has been investigated both theoretically and experimentally. In order to have a clear understanding, the stimulated Raman scattering process has been treated both semi-classically and quantum mechanically. The semi-classical treatment gives an insight into the coherent properties of the interaction process and the connection between spontaneous and stimulated scattering process, whereas the quantum treatment explains the growth of Stokes photons from the input noise which arises from the spontaneous scattering. The most crucial parameter in selecting the Raman media, namely, the stimulated Raman scattering gain coefficient at first Stokes wavelength has been calculated in the forward direction for the molecular gases, H_2, HD, D_2, and CH _4 at different commercially available pump wavelengths and different pressures of the gain media for both room and liquid nitrogen temperatures. A simple theoretical model has been developed to explain the forward/backward gain asymmetry in stimulated Raman scattering process. The calculated backward stimulated Brillouin gain coefficients in CH_4 and H _2 explain the discrepancy between the calculated and experimental threshold for the first Stokes conversion in the backward direction due to stimulated Raman scattering process. The generation of second or higher order Stokes, first and higher order anti-Stokes are explained from the theory of four-wave mixing process. The initiation of optical break down from plasma formation due to multi-photon absorption/ionization is qualitatively explained using a simple classical model. Experiments have been performed to generate multiple Stokes and anti-Stokes radiation due to stimulated Raman scattering and four-wave mixing process, in the forward direction of CH_4 and only first Stokes radiation in the backward direction of CH _4 and H_2 in a 44 cm long Raman cell. The blue-green radiation (S _1 and S_2) is generated in a compact (20 cm) and miniature (8cm) Raman cells in H_2. Various optimization techniques, namely, varying the pressure of the gain medium, pump energy, focal spot of the focusing beam, and the repetition rate of the pump beam by keeping three of the four variables constant at a time are used to maximize the Raman components. Optical breakdown is observed both in the compact and miniature hydrogen Raman laser at higher pump energy and repetition rates of the pump beam. In addition to the Raman components, the observation CH band in the CH_4 Raman cell is due to the multiphoton absorption leading to dissociative excitation.

Karuppasamy, Sentrayan

136

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

E-print Network

IUPAC-NIST Solubility Data Series 70. Solubility of Gases in Glassy Polymers Volume Editors Russell Synthesis, Moscow, Russia Received December 11, 1998 Solubility of gases in polymers is an important- cessing. However, by far the main interest in the solubility of gases in polymers, and especially

Magee, Joseph W.

137

(Desulfurization of fuel gases)  

SciTech Connect

The objective of this work was to demonstrate that solid solutions of cerium oxide (CeO{sub 2}) and other altervalent oxides (doped CeO{sub 2}) were capable of removing more H{sub 2}S from fuel gases than Ceo{sub 2} without any dopant. The ability of undoped CeO{sub 2} to remove H{sub 2}S from fuel gases had been determined with a previous DOE/SBIR grant. To make the results obtained under the two grants comparable, the procedures for all phases of this work duplicated that used previously as closely as possible. The sorbents GDC proposed to investigate were: (1) undoped CeO{sub 2}, (2) CeO{sub 2} doped with 5 mole % (5 m/o) magnesium oxide (MgO), and (3) CeO{sub 2} doped with 5 m/o lanthanum oxide (La{sub 2}O{sub 3}). Three additional sorbents: (1) CeO{sub 2} doped with 5 m/o strontium oxide (SrO), (2) CeO{sub 2} doped with 10 m/o SrO, and (2) CeO{sub 2} doped with 10 m/o La{sub 2}O{sub 3} were also investigated. All of these sorbents were prepared using the Marcilly technique.

Not Available

1991-12-15

138

Advanced Global Atmospheric Gases Experiment (AGAGE)  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

139

Control of pollutants in flue gases and fuel gases  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 Flue gases and fuel gases: combustion, gasification, pyrolysis, incineration and other and gasification technologies for heat and power . . . . . . . . 2-3 2.4 Waste incineration and waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.3 Formation of sulphur compounds during combustion and gasification . . 3-5 3.4 Emission

Zevenhoven, Ron

140

Control of pollutants in flue gases and fuel gases  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 Flue gases and fuel gases: combustion, gasification, pyrolysis, incineration and other and gasification technologies for heat and power . . . . . . . . 2-3 2.4 Waste incineration and waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.3 Formation of sulphur compounds during combustion and gasification . 3-5 3.4 Emission

Laughlin, Robert B.

141

Carbon dioxide and other greenhouse gases  

SciTech Connect

The authors address the issue of the impact of the greenhouse gases on the earth's climate. It is characterized by two equally challenging facts. The first is that a climatic change must occur, since it is impossible to perturb the earth's radiation budget without perturbing the system of which that budget is a key element. The second is that no one can say at present when exactly that change will occur, whether it will take place at the same rate everywhere on earth, what changes will be involved at a regional scale, nor whether it may even be beneficial in some ways. They suggest policy actions necessary to counteract these adverse consequences.

Fantechi, R.; Ghazi, A.

1989-01-01

142

Kinetic Molecular Theory of Gases  

NSDL National Science Digital Library

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.

David N. Blauch

143

Greenhouse Gases: A Closer Look  

NSDL National Science Digital Library

This lesson covers different aspects of the major greenhouse gases - water vapor, carbon dioxide, methane, nitrous oxides and CFCs - including some of the ways in which human activities are affecting the atmospheric concentrations of these key greenhouse gases. This is lesson six in a nine-lesson module about climate change.

King's Centre for Visualization in Science

144

Voluntary Reporting of Greenhouse Gases  

EIA Publications

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.

2011-01-01

145

What are greenhouse gases? Many chemical compounds in the atmosphere act as  

E-print Network

What are greenhouse gases? Many chemical compounds in the atmosphere act as greenhouse gases the atmosphere1 . They absorb some and radiate it back down to the Earth. This phenomenon, called the greenhouse. Without the greenhouse effect, the Earth's average surface temperature would be about 60° Fahrenheit

146

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

SciTech Connect

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.

Not Available

1990-01-01

147

Environmental implications of anesthetic gases.  

PubMed

For several decades, anesthetic gases have greatly enhanced the comfort and outcome for patients during surgery. The benefits of these agents have heavily outweighed the risks. In recent years, the attention towards their overall contribution to global climate change and the environment has increased. Anesthesia providers have a responsibility to minimize unnecessary atmospheric pollution by utilizing techniques that can lessen any adverse effects of these gases on the environment. Moreover, health care facilities that use anesthetic gases are accountable for ensuring that all anesthesia equipment, including the scavenging system, is effective and routinely maintained. Implementing preventive practices and simple strategies can promote the safest and most healthy environment. PMID:23241038

Yasny, Jeffrey S; White, Jennifer

2012-01-01

148

Investigating and Using Biomass Gases  

NSDL National Science Digital Library

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 theyâll 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.

Benson, Eric; Highfill, Melissa

2012-07-03

149

Degenerate quantum gases of strontium  

E-print Network

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.

Stellmer, Simon; Killian, Thomas C

2013-01-01

150

IMG, interferometric measurement of greenhouse gases from space  

NASA Astrophysics Data System (ADS)

A Michelson interferometer is under development as a payload of the ADEOS satellite. It will measure the spectra of terrestrial thermal infrared radiation with a nadir view in 700-3,000 cm-1 wavenumber region with an apodized resolution of 0.1 cm-1. Using those measured spectra, we will retrieve the altitude profiles of atmospheric temperature and the concentrations of greenhouse gases such as H2O, CO2, CH4, N2O, CO and O3. Our final goal is to observe horizontal structure in greenhouse gas concentrations and to infer the global distribution of the emission sources of greenhouse gases.

Ogawa, T.; Shimoda, H.; Hayashi, M.; Imasu, R.; Ono, A.; Nishinomiya, S.; Kobayashi, H.

1994-01-01

151

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

NASA Technical Reports Server (NTRS)

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

Temim, Tea; Dwek, Eli

2013-01-01

152

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

SciTech Connect

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

Temim, Tea; Dwek, Eli, E-mail: tea.temim@nasa.gov [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-09-01

153

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

SciTech Connect

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.

Seager, Richard

2014-12-08

154

High field optical nonlinearities in gases  

NASA Astrophysics Data System (ADS)

Optical femtosecond self-channeling in gases, also called femtosecond filamentation, has become an important area of research in high field nonlinear optics. Filamentation occurs when laser light self-focuses in a gas owing to self-induced nonlinearity, and then defocuses in the plasma generated by the self-focused beam. The result of this process repeating itself multiple times is an extended region of plasma formation. Filamentation studies have been motivated by the extremely broad range of applications, especially in air, including pulse compression, supercontinuum generation, broadband high power terahertz pulse generation, discharge triggering and guiding, and remote sensing. Despite the worldwide work in filamentation, the fundamental gas nonlinearities governing self-focusing had never been directly measured in the range of laser intensity up to and including the ionization threshold. This dissertation presents the first such measurements. We absolutely measured the temporal refractive index change of O2, N2, Ar, H2, D2 and N2O caused by highfield ultrashort optical pulses with single-shot supercontinuum spectral interferometry, cleanly separating for the first time the instantaneous electronic and delayed rotational nonlinear response in diatomic gases. We conclusively showed that a recent claim by several European groups that the optical bound electron nonlinearity saturates and goes negative is not correct. Such a phenomenon would preclude the need for plasma to provide the defocusing contribution for filamentation. Our results show that the 'standard model of filamentation', where the defocusing is provided by plasma, is correct. Finally, we demonstrated that high repetition rate femtosecond laser pulses filamenting in gases can generate long-lived gas density `holes' which persist on millisecond timescales, long after the plasma has recombined. Gas density decrements up to ~20% have been measured. The density hole refilling is dominated by thermal diffusion. These density holes will affect all other experiments involving nonlinear high repetition-rate laser pulse energy absorption by gases.

Cheng, Yu-Hsiang

155

Radiation Pressure Against Perfect Reflectors  

Microsoft Academic Search

The concept of radiation pressure exerted against a reflecting surface by electromagnetic waves and by sound waves in gases is a familiar one. The absence of radiation pressure for sound waves in a ``linear medium'' is becoming well known. The equations are somewhat different for the radiation pressure for these two cases where the radiation pressure is not zero. The

J. Elmer Rhodes

1953-01-01

156

The strange gases of Jupiter and Saturn  

NASA Technical Reports Server (NTRS)

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.

Noll, Keith S.

1990-01-01

157

Environmental monitoring of flammable and toxic gases  

SciTech Connect

An optical remote sensing method and system for detecting flammable and toxic atmospheres are described in the present paper. The method is particularly useful for detecting flammable hydrocarbon vapours in hazardous areas such as: tank farms and storage areas of petrochemicals, engine rooms where leaks of fuels create an explosion and fire hazard, migrating flammable clouds from production/storage/transportation sites. The method also enables the detection of toxic gases like H{sub 2}S, Ammonia, NOx, etc at very low concentration (PPM) in air. Such detection capability is essential to provide alarm in case of a hazardous condition in sensitive areas and offer at the same time the automatic activation of control means (fire suppression or neutralization system). The method employs remote sensing electro-optical means and uses spectral analysis in the UN and IR spectral bands to detect and identify the presence of flammable vapors, differentiate between paraffins and aromatics, toxic gases, various air pollutants or obscuration conditions. Various atmospheric conditions (fog, rain, snow) as well as false alarm stimulus (radiation sources, smoke and particles) are discussed and test results on laboratory and field scales up to 100 meters detection range are presented.

Jacobson, E. [Peckman Industrial Park, Cedar Grove, NJ (United States); Spectro, Y. [SPECTRONIX, LTD., Sderot (Israel)

1997-12-31

158

Atmospheric Radiation Measurement Program facilities newsletter, July 2001.  

SciTech Connect

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

Holdridge, D. J.

2001-07-23

159

Hot Topics in Cold Gases  

E-print Network

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.

Robert Seiringer

2009-08-25

160

The state of greenhouse gases in the atmosphere using global observations through 2011  

NASA Astrophysics Data System (ADS)

The Global Atmosphere Watch (GAW) Programme of the World Meteorological Organization (WMO) provides a framework for global observations and assessment of the state and development of atmospheric composition, including greenhouse gases. It puts stringent requirements on the quality of the observations, and these requirements are evaluated every two years. Results of global analysis of the observational data are reported annually in the WMO/GAW Annual Greenhouse Gas Bulletin. Bulletin No. 8 represents the results for the year 2011. This bulletin highlights the importance of carbon sinks (ocean and terrestrial biosphere) for anthropogenic CO2 emissions. Observations used for global analysis are collected at more than 100 sites worldwide for CO2 and CH4 and at a smaller number of sites for other greenhouse gases. Globally averaged dry-air mole fractions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) reached new highs in 2011, with CO2 at 390.9 ± 0.1 ppm, CH4 at 1813 ± 2 ppb and N2O at 324.2 ± 0.1 ppb. These values constitute 140%, 259% and 120% of pre-industrial (before 1750) levels, respectively. The increase of the annual mean CO2 mole fraction from 2010 to 2011 amounted to 2.0 ppm, which is greater than the average growth rate for the 1990s (~ 1.5 ppm/yr) and is equal to the average for the past decade (~ 2.0 ppm/yr). The globally averaged CH4 mole fraction increased by 5 ppb from 2010 to 2011. The growth rate of CH4 decreased from ~ 13 ppb/yr during the early 1980s to near zero during 1999-2006. Since 2007, atmospheric CH4 has been increasing again, averaging ~ 5 ppb/yr. The growth rate of N2O in 2011 was 1.0 ppb/yr, which is substantially greater than the average over the last 10 years (0.75 ppb/yr). The NOAA Annual Greenhouse Gas Index (AGGI) has been defined as the ratio of total radiative forcing due to long-lived greenhouse gases for any year for which adequate global measurements exist to that which was present in 1990. The AGGI in 2011 was 1.30 (corresponding to 2.84 W-m2 of global radiative forcing, relative to 1750, of all long-lived greenhouse gases). The AGGI indicates an increase in radiative forcing by all long-lived greenhouse gases of 30% since 1990 and of 1.2% from 2010 to 2011, while the radiative forcing by all long-lived greenhouse gases in 2011 corresponded to a CO2-equivalent mole fraction of 473 ppm (http://www.esrl.noaa.gov/gmd/aggi).

Tarasova, Oksana; Koide, Hiroshi; Dlugokencky, Ed; Montzka, Stephen A.; Griffith, David; Brunke, Ernst; Scheel, Hans-Eckhart; Laurila, Tuomas; Weller, Rolf; Butler, James H.

2013-04-01

161

Quantum Gases in Optical Lattices  

NASA Astrophysics Data System (ADS)

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

Barmettler, Peter; Kollath, Corinna

2015-09-01

162

Radiation Laws  

NSDL National Science Digital Library

This site lists physical laws that describe radiation. Topics covered include the Plank Radiation Law, and the Wien and Stefan-Boltzmann Laws. The site also features a table summarizing the blackbody temperatures necessary to give a peak for emitted radiation in various regions of the spectrum, and three Java applets illustrating important properties of blackbody radiation.

Astronomy, Department O.; Knoxville, University O.

163

Feshbach Resonances in Ultracold Gases  

NASA Astrophysics Data System (ADS)

In this chapter, we describe scattering resonance phenomena in general, and focus on the mechanism of Feshbach resonances, for which a multi-channel treatment is required. We derive the dependence of the scattering phase shift on magnetic field and collision energy. From this, the scattering length and effective range coefficient can be extracted -- expressions which are particularly useful for ultracold gases.

Kokkelmans, Servaas

2015-09-01

164

Interaction quenches of Fermi gases  

SciTech Connect

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

Uhrig, Goetz S. [Lehrstuhl fuer Theoretische Physik I, Technische Universitaet Dortmund, Otto-Hahn Strasse 4, D-44221 Dortmund (Germany)

2009-12-15

165

Greenhouse gases thinning the thermosphere  

NSDL National Science Digital Library

Orbital decay rates of satellites and other objects that have flown continually for more than 30 years were analyzed to determine the concentrations of greenhouse gases in the thermosphere. A decrease of 25 percent per decade was found in the thermosphere's density since 1966. Implications are discussed.

Emmert et al.

166

Greenhouse effect of chlorofluorocarbons and other trace gases  

NASA Technical Reports Server (NTRS)

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.

Hansen, James; Lacis, Andrew; Prather, Michael

1989-01-01

167

Radiative interactions in nonequilibrium flows  

NASA Technical Reports Server (NTRS)

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

Tiwari, S. N.; Chandrasekhar, R.

1992-01-01

168

Rare gases systematics and mantle structure  

NASA Technical Reports Server (NTRS)

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.

Allegre, C. J.; Staudacher, T.

1994-01-01

169

The toxicological properties of petroleum gases.  

PubMed

To characterize the toxicological hazards of petroleum gases, 90-day inhalation toxicity (Organization for Economic Cooperation and Development [OECD] 413) and developmental toxicity (OECD 414) tests were conducted with liquefied propane gas (LPG) at concentrations of 1000, 5000, or 10,000 ppm. A micronucleus test (OECD 474) of LPG was also conducted. No systemic or developmental effects were observed; the overall no observed adverse effect concentration (NOAEC) was 10,000 ppm. Further, there was no effect of LPG exposure at levels up to 10,000 ppm on micronucleus induction and no evidence of bone marrow toxicity. Other alkane gases (ethane, propane, n-butane, and isobutane) were then evaluated in combined repeated exposure studies with reproduction/development toxicity screening tests (OECD 422). There were no toxicologically important changes in parameters relating to systemic toxicity or neurotoxicity for any of these gases at concentrations ranging from 9000 to 16,000 ppm. There was no evidence of effects on developmental or reproductive toxicity in the studies of ethane, propane, or n-butane at the highest concentrations tested. However, there was a reduction in mating in the high-exposure group (9000 ppm) of the isobutane study, which although not significantly different was outside the range previously observed in the testing laboratory. Assuming the reduction in mating to have been toxicologically significant, the NOAEC for the isobutane reproductive toxicity screening test was 3000 ppm (7125 mg/m(3)). A method is proposed by which the toxicity of any of the 106 complex petroleum gas streams can be estimated from its composition. PMID:24179026

McKee, Richard H; Herron, Deborah; Saperstein, Mark; Podhasky, Paula; Hoffman, Gary M; Roberts, Linda

2014-01-01

170

High order harmonic generation in rare gases  

SciTech Connect

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.

Budil, K.S.

1994-05-01

171

40 CFR 86.1514 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

... false Analytical gases. 86.1514 Section...CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL...Methanol-Fueled Natural Gas-Fueled, and Liquefied Petroleum Gas-Fueled Diesel-Cycle...1514 Analytical gases. (a) The...

2010-07-01

172

Ground-based measurements of atmospheric trace gases near Saint-Petersburg, Russia  

NASA Astrophysics Data System (ADS)

Regular ground-based measurements of characteristics of atmospheric gas composition have been acquired at St. Petersburg State University (59°88' N, 29°83' E) since 1991. Equipment and techniques for interpreting the groundbased observations using measurements of spectra of direct solar IR radiation, zenith scattered UV and visible radiation are described. Main attention is centered on long-term variations of different trace gases, results of complex measurements of different atmospheric gases (O3, CO2, N2O, NO2, HF, HCl, HNO3 etc.) by Fourier spectrometer Bruker, comparisons of various ground-based methods for measuring the total columns of trace gases and the validation of different satellite measurements of total columns of trace gases.

Timofeyev, Yuriy; Poberovsky, Anatoly; Makarova, Maria; Polyakov, Alexander; Ionov, Dmitry; Virolainen, Yana; Kostsov, Vladimir; Kshevetskaya, Marina; Rakitin, Anton; Osipov, Sergey; Imhasin, Hamud; Frantsuzova, Inna

2013-05-01

173

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

SciTech Connect

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.

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

1995-12-31

174

Energy gases - the methane age and beyond  

Microsoft Academic Search

The combustion of fossil fuels results in the emissions of gases and pollutants that produce adverse ecological effects. Evidence is also accumulating that suggests they may also cause global climate change. The combustion gases that are connected with global climate change are primarily carbon dioxide (CO[sub 2]) and to a lesser degree methane (CH[sub 4]). All of these gases already

Nakicenovic

1993-01-01

175

Emissions of greenhouse gases in the United States 1997  

SciTech Connect

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.

NONE

1998-10-01

176

Hot and Cold Ideal Gases  

NSDL National Science Digital Library

The EJS Hot and Cold Ideal Gases model simulates the mixing of hot and cold two-dimensional ideal gases in a square box. This simulation can be used as part of the activity described in "The Statistical Interpretation of Entropy: An Activity" by Todd Timberlake, to be published in The Physics Teacher. In the model, one gas is initially confined to the left side of the box while the other gas is confined to the right side. An animation window shows the motion of the particles in the box, while an optional graph window plots the temperature of each side of the box, which is determined by measuring the average KE of the particles on each side. The initial number of particles and temperature on each side of the square can be changed and a button allows the user to reverse the particle velocities at any time. The user can modify this simulation if EJS is installed locally by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. EJS Hot and Cold Ideal Gases model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_entropy_HotAndColdIdealGases.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional EJS models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or EJS.

Timberlake, Todd

2010-07-01

177

Nonhomologous end-joining repair plays a more important role than homologous recombination repair in defining radiosensitivity after exposure to high-LET radiation.  

PubMed

DNA double-strand breaks (DSBs) induced by ionizing radiation pose a major threat to cell survival. The cell can respond to the presence of DSBs through two major repair pathways: homologous recombination (HR) and nonhomologous end joining (NHEJ). Higher levels of cell death are induced by high-linear energy transfer (LET) radiation when compared to low-LET radiation, even at the same physical doses, due to less effective and efficient DNA repair. To clarify whether high-LET radiation inhibits all repair pathways or specifically one repair pathway, studies were designed to examine the effects of radiation with different LET values on DNA DSB repair and radiosensitivity. Embryonic fibroblasts bearing repair gene (NHEJ-related Lig4 and/or HR-related Rad54) knockouts (KO) were used and their responses were compared to wild-type cells. The cells were exposed to X rays, spread-out Bragg peak (SOBP) carbon ion beams as well as with carbon, iron, neon and argon ions. Cell survival was measured with colony-forming assays. The sensitization enhancement ratio (SER) values were calculated using the 10% survival dose of wild-type cells and repair-deficient cells. Cellular radiosensitivity was listed in descending order: double-KO cells > Lig4-KO cells > Rad54-KO cells > wild-type cells. Although Rad54-KO cells had an almost constant SER value, Lig4-KO cells showed a high-SER value when compared to Rad54-KO cells, even with increasing LET values. These results suggest that with carbon-ion therapy, targeting NHEJ repair yields higher radiosensitivity than targeting homologous recombination repair. PMID:25117625

Takahashi, Akihisa; Kubo, Makoto; Ma, Hongyu; Nakagawa, Akiko; Yoshida, Yukari; Isono, Mayu; Kanai, Tatsuaki; Ohno, Tatsuya; Furusawa, Yoshiya; Funayama, Tomoo; Kobayashi, Yasuhiko; Nakano, Takashi

2014-09-01

178

Climate Change and Greenhouse Gases  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

179

Probing the effect of Gases on Activated Lunar Simulant  

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

180

Assessment of radiation damage behaviour in a large collection of empirically optimized datasets highlights the importance of unmeasured complicating effects  

PubMed Central

The radiation damage behaviour in 43 datasets of 34 different proteins collected over a year was examined, in order to gauge the reliability of decay metrics in practical situations, and to assess how these datasets, optimized only empirically for decay, would have benefited from the precise and automatic prediction of decay now possible with the programs RADDOSE [Murray, Garman & Ravelli (2004 ?). J. Appl. Cryst. 37, 513–522] and BEST [Bourenkov & Popov (2010 ?). Acta Cryst. D66, 409–419]. The results indicate that in routine practice the diffraction experiment is not yet characterized well enough to support such precise predictions, as these depend fundamentally on three interrelated variables which cannot yet be determined robustly and practically: the flux density distribution of the beam; the exact crystal volume; the sensitivity of the crystal to dose. The former two are not satisfactorily approximated from typical beamline information such as nominal beam size and transmission, or two-dimensional images of the beam and crystal; the discrepancies are particularly marked when using microfocus beams (<20?µm). Empirically monitoring decay with the dataset scaling B factor (Bourenkov & Popov, 2010 ?) appears more robust but is complicated by anisotropic and/or low-resolution diffraction. These observations serve to delineate the challenges, scientific and logistic, that remain to be addressed if tools for managing radiation damage in practical data collection are to be conveniently robust enough to be useful in real time. PMID:21525647

Krojer, Tobias; von Delft, Frank

2011-01-01

181

Angular correlation studies in noble gases  

NASA Technical Reports Server (NTRS)

There has been a recent revival of interest in the measurement of angular correlation of annihilation photons from the decay of positrons and positronium in gases. This revival has been stimulated by the possibility offered by the technique to shed new light on the apparently low positronium formation fraction in the heavier noble gases and to provide information on positronium quenching processes in gases such as oxygen. There is also the potential for learning about positronium slowing down in gases. This review focuses on experimental noble gas work and considers what new information has been, and may be, gained from these studies.

Coleman, P. G.

1990-01-01

182

Generalized sqrt(epsilon)-law. The role of unphysical source terms in resonance line polarization transfer and its importance as an additional test of NLTE radiative transfer codes  

E-print Network

Context. A derivation of a generalized sqrt(epsilon)-law for nonthermal collisional rates of excitation by charged perturbers is presented. Aims. Aim of this paper is to find a more general analytical expression for a surface value of the source function which can be used as an addtional tool for verification of the non-LTE radiative transfer codes. Methods. Under the impact approximation hypothesis, static, one-dimensional, plane-parallel atmosphere, constant magnetic field of arbitrary strength and direction, two-level atom model with unpolarized lower level and stimulated emission neglected, we introduce the unphysical terms into the equations of statistical equilibrium and solve the appropriate non-LTE integral equations. Results. We derive a new analytical condition for the surface values of the source function components expressed in the basis of irreducible spherical tensors.

Jiri Stepan; Veronique Bommier

2007-04-12

183

Process for treating gases in the ammonia synthesis. [separation and dehydration of gases leaving synthesis reactor  

Microsoft Academic Search

In the synthesis of ammonia, a process is disclosed for treating the gases flowing from the synthesis reactor wherein those gases flow through a film absorber countercurrent to a cooled aqueous film to extract ammonia which is withdrawn as a strong solution from the absorber and scrubbed gases are combined for recycle with a stream of fresh feed which is

Guadalupi

1977-01-01

184

Fluorescence Imaging of Quantum Gases  

NASA Astrophysics Data System (ADS)

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

Weitenberg, Christof

2015-09-01

185

Greenhouse Gases: The Overlooked Sources  

NSDL National Science Digital Library

This radio broadcast, which took place during the Kyoto Conference on global warming, discusses well-known and more obscure sources of greenhouse gases. Solutions to reduce carbon emissions are discussed, including creating fuel with less carbon in it (biomass fuels); reducing driving by increasing the cost of fuel; and improving vehicle fuel economy. The broadcast then introduces the topic of methane as a greenhouse gas; although less is emitted, it is about fifty times more effective than carbon dioxide at warming the planet. Cattle are a major source of methane; some ideas are introduced for monitoring and reducing their emissions. There is also discussion of whether global warming could be a result of natural variability as opposed to the result of a human-caused greenhouse effect. The broadcast is 49 minutes and 39 seconds in length.

186

Gases in agricultural slurry stores.  

PubMed

The evolution of gases during the handling of animal slurry was investigated at five sites. Particular attention was paid to the mixing and emptying operations since it is when performing these that personnel are most likely to be at risk of exposure. The main hazard was found to be high transient concentrations of hydrogen sulphide presenting in some cases a serious acute toxicity problem. Time-weighted average exposures did not generally indicate any long-term exposure risk. Other features noted were the evolution of ammonia and methane, although not at high levels, and some increase in the carbon dioxide concentration. Some reduction in oxygen concentration was measured, but generally the risk of poisoning by hydrogen sulphide was more serious than the risk of asphyxiation. PMID:2042881

Groves, J A; Ellwood, P A

1991-04-01

187

Energy Cascades in Granular Gases  

NASA Astrophysics Data System (ADS)

A new class of stationary states in granular gases where energy is transfered from large velocity scales to small velocity scales is found. These steady-states exist for arbitrary collision rules and arbitrary dimension. Their signature is a velocity distribution f(v) with an algebraic high-energy tail, f(v)˜v^-?. The exponent ? is obtained analytically and it varies continuously with the spatial dimension, the homogeneity index characterizing the collision rate, and the restitution coefficient. These stationary states are realized in numerical simulations in which energy is injected into the system by infrequently boosting particles to high velocities. It is proposed that these states may be realized experimentally in driven granular systems.

Ben-Naim, Eli

2005-03-01

188

Granular gases under extreme driving  

NASA Astrophysics Data System (ADS)

We study inelastic gases in two dimensions using event-driven molecular-dynamics simulations. Our focus is the nature of the stationary state attained by rare injection of large amounts of energy to balance the dissipation due to collisions. We find that under such extreme driving, with the injection rate much smaller than the collision rate, the velocity distribution has a power-law high-energy tail. The numerically measured exponent characterizing this tail is in excellent agreement with predictions of kinetic theory over a wide range of system parameters. We conclude that driving by rare but powerful energy injection leads to a well-mixed gas and constitutes an alternative mechanism for agitating granular matter. In this distinct nonequilibrium steady state, energy cascades from large to small scales. Our simulations also show that when the injection rate is comparable with the collision rate, the velocity distribution has a stretched exponential tail.

Kang, W.; Machta, J.; Ben-Naim, E.

2010-08-01

189

Effects of traces of molecular gases (hydrogen, nitrogen) in glow discharges in noble gases  

NASA Astrophysics Data System (ADS)

The "Grimm" type of low pressure glow discharge source, introduced some forty years ago, has proved to be a versatile analytical source. A flat sample is used as the cathode and placed about 0.2mm away from the end of a hollow tubular anode leading to an obstructed discharge. When the source was first developed, it was used for the direct analysis of solid metallic samples by optical emission spectroscopy (OES), normally with argon as the plasma gas; it was soon found that, using suitable electrical parameters, the cathode material was sputtered uniformly from a circular crater of diameter equal to that of the tubular anode, so that the technique could be used for compositional depth profile analysis (CDPA). Over the years the capability and applications of the technique have steadily increased. The use of rf powered discharges now permits the analysis of non-conducting layers and samples; improved instrumental design now allows CDPA of ever thinner layers (e.g. resolution of layers 5 nm thick in multilayer stacks is possible). For the original bulk material application, pre-sputtering could be used to remove any surface contamination but for CDPA, analysis must start immediately the discharge is ignited, so that any surface contamination can introduce molecular gases into the plasma gas and have significant analytical consequences, especially for very thin layers; in addition, many types of samples now analysed contain molecular gases as components (either as occluded gas, or e.g. as a nitride or oxide), and this gas enters the discharge when the sample is sputtered. It is therefore important to investigate the effect of such foreign gases on the discharge, in particular on the spectral intensities and hence the analytical results. The presentation will concentrate mainly on the effect of hydrogen in argon discharges, in the concentration range 0-2 % v/v but other gas mixtures (e.g. Ar/N_2, Ne/H_2) will be considered for comparison. In general, the introduction of molecular gases can change the discharge impedance, alter the sputtering rate and crater profile and cause changes in the absolute and relative intensities of lines in both the atomic and ionic spectra of the sample element and the plasma gas. The authors wish to acknowledge financial support from EC funded Analytical Glow Discharge Research Training Network GLADNET, contract no. MRTN-CT-2006-035459. P. Smid thanks the Deutsche Forschungsgemeinschaft (Ref 436 TSE 17/7/06) for support while carrying out experiments at IFW Dresden.

Steers, E. B. M.; Smid, P.; Hoffmann, V.

2008-07-01

190

Continuous Processing with Mars Gases  

NASA Technical Reports Server (NTRS)

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

Parrish, Clyde; Jennings, Paul; Delgado, Hugo (Technical Monitor)

2001-01-01

191

Continuous Processing With Mars Gases  

NASA Technical Reports Server (NTRS)

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

Parrish, Clyde; Jennings, Paul

2000-01-01

192

Multiple direct and sequential Auger effect in the rare gases  

SciTech Connect

The use of a magnetic bottle spectrometer with synchrotron radiation allows multi dimensional electron spectroscopy to be performed by detecting in coincidence all electrons (2, 3, 4) ejected in multiple ionization events. Multiple Auger effect following inner-shell ionization can be investigated in this way. Application of the technique to rare gases (Xe 4d and Kr 3d) double Auger decay reveals all the energy pathways involved. The dominant decay path proceeds by Auger cascade through autoionizing states of the doubly charged ion. Processes where 3 electrons are involved are also observed as direct double Auger and as involving precursor Rydberg series.

Penent, F.; Lablanquie, P.; Palaudoux, J.; Andric, L. [LCP-MR, CNRS et UPMC, 11, rue P. and M. Curie, 75231 Paris (France); Aoto, T.; Ito, K. [Photon Factory, IMSS, KEK, Tsukuba 305-0801 (Japan); Hikosaka, Y. [IMS, Okazaki 444-8585 (Japan); Feifel, R.; Eland, J. H. D. [PTCL, Oxford University, Oxford (United Kingdom)

2006-01-09

193

Radiation technology for environmental conservation  

NASA Astrophysics Data System (ADS)

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

Machi, S.

194

Predict thermal conductivities of pure gases  

Microsoft Academic Search

The programs presented for the TI-59 programmable calculator can determine the thermal conductivity of pure gases and gases at low pressures as well as the effect of pressure on conductivity. They are based on correlations by Eucken, Stiel-Thodos, Misic-Thodos, Roy-Thodos, and Redlich-Kwong.

1981-01-01

195

Rare Gases in the Chondrite Renazzo  

Microsoft Academic Search

A detailed analysis of the rare gas content of the chondrite Renazzo is presented. Fractions of different isotopic composition are separated by heating the sample to successively higher temperatures. The abundance and isotopic composition of the gases is similar to that in the carbonaceous chondrite Murray, with a high percentage of so-called primordial gas. For the light rare gases this

J. H. Reynolds; G. Turner

1964-01-01

196

Design of a multifunctional and portable detector for indoor gases  

NASA Astrophysics Data System (ADS)

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

Zhang, Liping; Wang, Yutian; Li, Taishan

2003-09-01

197

Hyperpolarized noble gases as contrast agents.  

PubMed

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

Zhou, Xin

2011-01-01

198

Isotopic composition of gases from mud volcanoes  

SciTech Connect

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

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

1985-09-01

199

Foundations of radiation hydrodynamics  

Microsoft Academic Search

This book is the result of an attempt, over the past few years, to gather the basic tools required to do research on radiating flows in astrophysics. The microphysics of gases is discussed, taking into account the equation of state of a perfect gas, the first and second law of thermodynamics, the thermal properties of a perfect gas, the distribution

D. Mihalas; B. W. Mihalas

1984-01-01

200

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

NASA Technical Reports Server (NTRS)

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.

Hansen, James E.; Lacis, Andrew A.

1990-01-01

201

XXII International conference on phenomena in ionized gases. Contributed papers 3  

Microsoft Academic Search

This report contains short papers\\/abstracts from the 22th international conferences on phenomena in ionized gases. Subject areas covered are: waves and instabilities; discharges and genreation of laser radiation; and generation and dynamics of plasma plasma. These papers have been cataloged elsewhere.

K. H. Becker; W. E. Carr; E. E. Kunhardt

1995-01-01

202

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

Microsoft Academic Search

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.

James E. Hansen; Andrew A. Lacis

1990-01-01

203

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

E-print Network

Classical disordered ground states: Super-ideal gases and stealth and equi-luminous materials University, Princeton, New Jersey, 08544, USA 3 Princeton Institute for the Science and Technology focus on three classes of configurations with unique radiation scattering characteristics: i "stealth

Torquato, Salvatore

204

Trace Gases and Aerosol in the Boundary Layer of the Northern Asia: TROICA Experiments  

Microsoft Academic Search

The TROICA experiment (Transcontinental Observations Into the Chemistry of the Atmosphere) started in 1995. A mobile railroad laboratory is being used for measurements of atmospheric gases, aerosol, solar radiation and meteorological parameters. The laboratory wagon is directly coupled to the locomotive of a passenger train traveling along electrified railroads of Russia. Eleven expeditions have been conducted to the moment of

N. F. Elanksy; A. E. Aloyan; E. V. Berezina; A. S. Elokhov; C. A. Brenninkmeijer; V. M. Kopeikin; K. B. Moeseenko; O. V. Lavrova; N. V. Pankratova; A. N. Safronov; R. A. Shumsky; A. I. Skorokhod; O. A. Tarasova; A. V. Vivchar; A. M. Grisenko

2007-01-01

205

Particle and power balance in a helicon operating with light gases [experiment  

Microsoft Academic Search

Measurements of input power, particle flow, radiation, electron density profiles, plasma flow, and electron temperature profiles over a range of input power, magnetic field, and neutral flow were used to do a power and particle balance during operation with light gases H, D, and He in the VASIMR experiment at the Advanced Space Propulsion Laboratory. In addition, an axial pressure

Roger D. Bengtson; J. N. Gibson; V. T. Jacobson; F. R. Chang-Diaz; J. P. Squire; G. E. McCaskill; J. E. McCoy; A. J. Petro; D. S. Winter; H. M. Jamison; E. A. Bering; T. W. Glover

2001-01-01

206

Sulfur species in volcanic gases.  

PubMed

A new analytical method for the determination of the sulfur species (SO2, H2S, S8(0)) in volcanic gases is proposed by revising, updating, and improving previous methods. The most significant advantages of the proposed procedure can briefly be summarized, as follows: (i) the reaction among sulfur species stops during the gas sampling by using preevacuated thorion-tapped vials with purified 0.15M Cd(OH)2 in 4 M NaOH to favor the precipitation of H2S as CdS; (ii) all the sulfur species (SO2, H2S, S8(0)) are analyzed by ion chromatography, after conversion to SO4, which allows the detection limit to be lowered significantly with respect to the previous studies; (iii) appropriate aliquots from intermediate steps may be used to determine other species commonly present in volcanic gases such as CO2, HCI, HF, HBr, HI, and so forth; (iv) determination of all the other gas species is not jeopardized by the proposed method, i.e., one single vial can be used for analyzing the full chemical composition of a volcanic gas with the exception of NH3. Statistical parameters calculated from gas sampling data at the F5 crater fumarole in Vulcano Island (Aeolian Islands, southern Italy), suggest that the standard error of mean (s/ root n) is higher for S (0.10), followed by SO2, H2S, and CO2 (0.04, 0.038, and 0.028, respectively). SO2 shows the higher variation coefficient (12.1%) followed by H2S, S, and CO2 (5.7, 1.5, and 0.8%, respectively). Furthermore, if the time dependence of sampling is taken into account, the measured values, instead of fluctuating in a random manner, tend to follow systematic patterns, out of statistical control, possibly suggesting a sort of natural fluctuation of the volcanic system. Other crater fumaroles from volcanic systems located in different geodynamical areas (Hawaii, USA, El Chichon, Mexico, Poas, Costa Rica) have been analyzed as well. PMID:11510838

Montegrossi, G; Tassi, F; Vaselli, O; Buccianti, A; Garofalo, K

2001-08-01

207

On the importance of searching for oscillations of the Jovian inner radiation belt with a quasi-period of 40 minutes  

NASA Astrophysics Data System (ADS)

Experiments aboard the Ulysses spacecraft discovered quasi-periodic bursts of relativistic electrons and of radio emissions with ~40-min period (QP-40) from the south polar direction of Jupiter in 1992 February. 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 a distance of ~2-3 RJ (where RJ is the radius of Jupiter), where relativistic electrons are known to be trapped using the diagnostics of synchrotron emissions, can execute global QP-40 magnetoinertial oscillations excited by arrivals of high-speed solar winds at the Jovian magnetosphere. 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 relativistic electron bursts. Highly beamed synchrotron emissions from such QP-40 burst electrons with small pitch angles relative to Jovian magnetic fields at ~30-40 RJ give rise to QP-40 radio bursts with typical frequencies <~0.2 MHz. We predict that the synchrotron brightness of the IRB should vary on QP-40 time-scales upon arrivals of high-speed solar winds with estimated magnitudes >~0.1 Jy, detectable by existing ground-based radio telescopes. The recent discovery of ~45-min pulsations of Jupiter's north polar X-ray hot spot by the High-Resolution Camera (HRC) of the Chandra spacecraft provides strong supporting circumstantial evidence that the IRB neighborhood did oscillate with QP-40 time-scales. Using the real-time solar wind data from the spacecraft Advanced Composition Explorer (ACE), we show here that such QP-40 pulsations of Jupiter's north polar X-ray hot spot did in fact coincide with the arrival of high-speed solar wind at Jupiter. We note also that properly sampled data of simultaneous far-ultraviolet images of auroral ovals obtained by the Hubble Space Telescope imaging spectrograph (HST-STIS) would have contained QP-40 oscillatory signatures. Based on our theoretical analysis, we offer several predictions that can be tested by further spacecraft and ground-based telescope observations.

Lou, Yu-Qing; Zheng, Chen

2003-09-01

208

49 CFR 173.307 - Exceptions for compressed gases.  

Code of Federal Regulations, 2010 CFR

... Exceptions for compressed gases. 173.307 Section 173...FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging... Exceptions for compressed gases. (a) The following materials...non-flammable, non-toxic gas; (ii) 12 L (3...

2010-10-01

209

49 CFR 174.201 - Class 2 (gases) material cylinders.  

Code of Federal Regulations, 2010 CFR

...2 2010-10-01 2010-10-01 false Class 2 (gases) material cylinders. 174.201... CARRIAGE BY RAIL Detailed Requirements for Class 2 (Gases) Materials § 174.201 Class 2 (gases) material cylinders. (a)...

2010-10-01

210

49 CFR 174.201 - Class 2 (gases) material cylinders.  

Code of Federal Regulations, 2013 CFR

...2 2013-10-01 2013-10-01 false Class 2 (gases) material cylinders. 174.201... CARRIAGE BY RAIL Detailed Requirements for Class 2 (Gases) Materials § 174.201 Class 2 (gases) material cylinders. (a)...

2013-10-01

211

Natural and anthropogenic trace gases in the southern hemisphere  

NASA Technical Reports Server (NTRS)

The complexity of the global environment makes it necessary that many important trace gases in the earth's atmosphere be measured on a global scale before predictions can be made regarding the effects of human activities on the environment. A description is presented of measurements of 14 atmospheric trace gases in the lower atmosphere (0-4 km) of the southern hemisphere. Concentrations are considered of CCl3F, CCl2F2, CHClF2, C2.Cl3.F3, CH3CCl3, CCl4, C2.Cl4, CH3I, CHCl3, CO, CH3Cl, CH4, N2O, and OCS. The obtained data are analyzed and interpreted to statistically quantify the possible differences of concentrations in and above the boundary layer, to model the vertical profile of CH3I, and to use the data in support of previous findings that CH4 is increasing in the atmosphere.

Rasmussen, R. A.; Khalil, M. A. K.; Crawford, A. J.; Fraser, P. J.

1982-01-01

212

Brane gases in the early Universe  

SciTech Connect

Over the past decade it has become clear that fundamental strings are not the only fundamental degrees of freedom in string theory. D-branes are also part of the spectrum of fundamental states. In this paper we explore some possible effects of D-branes on early Universe string cosmology, starting with two key assumptions: firstly that the initial state of the Universe corresponded to a dense, hot gas in which all degrees of freedom were in thermal equilibrium, and secondly that the topology of the background space admits one-cycles. We argue by t duality that in this context the cosmological singularities are not present. We derive the equation of state of the brane gases and apply the results to suggest that, in an expanding background, the winding modes of fundamental strings will play the most important role at late times. In particular, we argue that the string winding modes will only allow four space-time dimensions to become large. The presence of brane winding modes with p>1 may lead to a hierarchy in the sizes of the extra dimensions.

Alexander, S.; Brandenberger, R.; Easson, D.

2000-11-15

213

Radiation Safety September 2013  

E-print Network

Radiation Safety Manual September 2013 Office of Environment, Health & Safety #12;RADIATION SAFETY of ionizing radiation as a valuable tool to extend fundamental knowledge. These activities are an important of radiation-producing machines and radioactive materials attests to the success of its radiation safety

California at Irvine, University of

214

40 CFR 1065.750 - Analytical gases.  

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

2014-07-01

215

40 CFR 92.112 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

216

Voluntary reporting of greenhouse gases, 1995  

SciTech Connect

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

NONE

1996-07-01

217

Denitrification of combustion gases. [Patent application  

DOEpatents

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.

Yang, R.T.

1980-10-09

218

Utilizing the waste heat in exhaust gases  

Microsoft Academic Search

The operation and technoeconomic indicators of VER1-VER5 waste-heat recovery units are described. The units, which utilize the heat in exhaust gases from heat-treat and preheat furnaces, are at the Energomashspetsstal Works in Kramtorsk.

V. K. Shlyk; D. T. Kirkach

1984-01-01

219

Comparing greenhouse gases for policy purposes  

E-print Network

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

Schmalensee, Richard

1993-01-01

220

40 CFR 92.112 - Analytical gases.  

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

2014-07-01

221

Nanoindentation of GaSe thin films  

PubMed Central

The structural and nanomechanical properties of GaSe thin films were investigated by means of X-ray diffraction (XRD) and nanoindentation techniques. The GaSe thin films were deposited on Si(111) substrates by pulsed laser deposition. XRD patterns reveal only the pure (000?l)-oriented reflections originating from the hexagonal GaSe phase and no trace of any impurity or additional phases. Nanoindentation results exhibit discontinuities (so-called multiple ‘pop-in’ events) in the loading segments of the load–displacement curves, and the continuous stiffness measurements indicate that the hardness and Young’s modulus of the hexagonal GaSe films are 1.8?±?0.2 and 65.8?±?5.6?GPa, respectively. PMID:22804961

2012-01-01

222

Detailed Investigations of Interactions between Ionizing Radiation and Neutral Gases  

SciTech Connect

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.

Landers, Allen L

2014-03-31

223

Greenhouse effects due to man-made perturbations of trace gases  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

224

Biological production of products from waste gases  

DOEpatents

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.

Gaddy, James L. (Fayetteville, AR)

2002-01-22

225

Quantum Polarization Spectroscopy of Ultracold Spinor Gases  

SciTech Connect

We propose a method for the detection of ground state quantum phases of spinor gases through a series of two quantum nondemolition measurements performed by sending off-resonant, polarized light pulses through the gas. Signatures of various mean-field as well as strongly correlated phases of F=1 and F=2 spinor gases obtained by detecting quantum fluctuations and mean values of polarization of transmitted light are identified.

Eckert, K. [Grup de Fisica Teorica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Zawitkowski, L. [Centrum Fizyki Teoretycznej, Polska Akademia Nauk, Warsaw 02668 (Poland); Sanpera, A. [ICREA and Grup de Fisica Teorica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Lewenstein, M. [ICREA and ICFO-Institut de Ciencies Fotoniques, E-08860 Castelldefels, Barcelona (Spain); Polzik, E. S. [ICFO-Institut de Ciencies Fotoniques, E-08860 Castelldefels, Barcelona (Spain); Niels Bohr Institute, Danish Quantum Optics Center-QUANTOP, Copenhagen University, Blegdamsvej 17, Copenhagen 2100 (Denmark)

2007-03-09

226

Source gases: Concentrations, emissions, and trends  

NASA Technical Reports Server (NTRS)

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.

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

227

Classification and generation of terrestrial rare gases  

NASA Technical Reports Server (NTRS)

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

Saito, K.

1978-01-01

228

Biogenic and anthropogenic trace gases in the atmosphere  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

229

Emissions of greenhouse gases in the United States 1996  

SciTech Connect

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

NONE

1997-10-01

230

Experimental Research of Pyrolysis Gases Cracking on Surface of Charcoal  

NASA Astrophysics Data System (ADS)

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.

Kosov, Valentin; Kosov, Vladimir; Zaichenko, Victor

231

Laser-based thermographic visualization and identification of gases  

NASA Astrophysics Data System (ADS)

This paper reports on investigations regarding the visualization of environmental relevant gases normally invisible to the human eye. The principle of this system is based on the backscatter absorption gas imaging technique developed by Lawrence Livermore National Laboratory and Laser Imaging Systems. Main advantages of this approach in comparison to conventional laser-based remote gas-sensing methods are reachable speed of localization, high sensitivity as well as the detection of multileakages. The applied method is based on infrared (IR)-technology consisting of a thermal imaging device and a tunable CO2-laser. Main aim of a project carried out at the Laser Zentrum Hannover e.V. is the computer based processing of spectroscopic and IR-image information provided by this technique. For this, several important parameters like the wavelength tuning precision, the dependence of the wavelength on the average output power of the laser source as well as the optical resolution have been investigated. The results show, that the BAGI-technology offers a large potential for future developments related to the observation of transparent gases. In addition to this the authors presents a new concept for an enhanced system that would not only be able to visualize gases but also capable of determining their direction of moving, computing their volume and forecasting their possible further spreading.

Haferkamp, Heinz; Seebaum, Dirk; Schroeder, Ulrich; Thuerk, Oliver

1997-05-01

232

ABSORPTION OF INHALED REACTIVE GASES  

EPA Science Inventory

In inhalation toxicology, an important concept involves the determination of dose as a major component for providing a perspective to judge the applicability of various toxicological results to human exposure conditions. This chapter reviewed some of the biological, physical, and...

233

Laser-based visualization of environmental crucial gases  

NASA Astrophysics Data System (ADS)

The principle of the presented visualization system is based on the backscatter absorption gas imaging technique. Applying this technique, developed by Lawrence Livermore National Laboratory and Laser Imaging Systems in the USA, it is possible to visualize a large amount of environmental relevant gases normally invisible to the human eye. An image of the spreading of gases is created from infrared (IR) laser radiation that is backscattered from the scenery background in the field of view of a special designed IR- camera. Gaseous components within this field of view absorb a portion of the emitted laser radiation at their specific absorption wavelength and cause an attenuation of a portion of the radiation, backscattered by the scenery background. This leads to a dark gas image on the video screen. Analyzing the wavelength of maximum attenuation then allows the identification of the observed gas. The applied method is based on commercially available IR technology consisting of a thermal imaging device and a tunable CO2-laser. Main advantages of this approach in comparison to conventional laser-based remote gas-sensing methods (i.e. Differential Absorption Lidar DIAL or Raman Lidar) are reachable speed of localization, high sensitivity as well as the detection of multileakages. Main aim of a project carried out at the Laser Zentrum Hannover is the computer based processing of spectroscopic and IR-image information provided by the visualization system described above. For this the dependence between the wavelength and the power output of the laser has to be known and so investigations have been carried out to determine this dependence.

Haferkamp, Heinz; Goede, Martin; Schroeder, Ulrich

1998-09-01

234

Ab initio Calculations of Solvation Processes in Volcanic Gases  

NASA Astrophysics Data System (ADS)

The structures and thermochemical properties of hydrated ions and neutral molecules play an important role in our understanding of solvent clustering and hydrogen bonding in the gas phase. Considerable effort therefore has been devoted to both the experimental and theoretical determination of stepwise hydration energies of geochemically important ions and neutral molecules with solvents, for instance H2O or H2S, over a broad range of temperatures typical of those encountered in volcanic gases. Because volcanic gases contain mutiple solute and solvent components which are subject to proton transfer, competive solvation and solvent switching, characterizing individual clusters has been a fundamental challenge to a molecular-level understanding of high temperature gas-phase solvation. However, recent advances in computational chemistry methods, especially Pople´s Gaussian (G-n) and complete basis set limit (CBS-x) model chemistries, now allow characterization of the dominant cluster structures and thermochemical properties of solute-solvent and solvent-solvent interactions in high temperature volcanic gases. Building on reported measurements of volcanic gases at Vesuvio, Italy, and Showa-Shinzan, Japan, as well as our recent investigations of ion-hydration we have re-examined the high temperature clustering equilibria of the small hydronium (H3O+) and ammonium (NH4+) ions as well as neutral ammonia and sulphur species with H2O and/or H2S using ab initio quantum chemical methods. From our study, we find that most of the gas phase ions tend to associate with a small number of H2O and H2S molecules to yield a hydrated ion cluster even at low humidities. Furthermore, inspection of van´t Hoff data demonstrate that (1) hydration energies of ions are shifted to less exergonic values as the solvent shell grows and the composition shifts from water-rich to hydrogen sulphide rich, (2) ion-cluster size increases with decreasing temperature at constant humidity, (3) attachment of H2S onto neutral ammonia is substantially more endergonic than the corresponding reaction with H2O and (4) temperature increases are reflected in a weakening of the hydrogen bonding in neutral ammonia clusters. For instance, we predict that the concentrations of NH3(H2O) clusters in fumarolic gases (H2O=740Torr) of the Showa- Shinzan volcano are 5.8x1014cm-3 at 371K but are reduced to 2.7x1013cm-3at 743K. In general, the observed energetic trends demonstrate the significance of hydrogen-bonded networks in both ionic and neutral solvent clusters at elevated temperatures.

Lemke, K.; Seward, T.

2006-12-01

235

The importance of the Montreal Protocol in protecting climate  

PubMed Central

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

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

2007-01-01

236

Air Pollution, Greenhouse Gases and Climate Change  

NASA Astrophysics Data System (ADS)

The global build up of greenhouse gases (GHGs), is the most significant environmental issue facing the planet. GHGs warm the surface and the atmosphere with significant implications for, rainfall, retreat of glaciers and sea ice, sea level, among other factors. What is less recognized, however, is a comparably major global problem dealing with air pollution. Until about ten years ago, air pollution was thought to be just an urban or a local problem. But new data have revealed that, due to fast long range transport, air pollution is transported across continents and ocean basins, resulting in trans-oceanic and trans-continental plumes of atmospheric brown clouds (ABCs) containing sub micron size particles, i.e, aerosols. ABCs intercept sunlight by absorbing as well as reflecting it, both of which lead to a large surface dimming. The dimming effect is enhanced further because aerosols nucleate more cloud drops which makes the clouds reflect more solar radiation. While the solar heating at the surface is reduced by aerosols in ABCs, the atmospheric solar heating increases due to soot solar absorption. The net difference between the dimming and the atmospheric solar heating is estimated be negative which contributes to a global cooling effect. The global cooling from this negative ABC forcing may have masked as much as 50% of the warming due to GHGs. We will identify regional and mega-city hot spots of ABCs. Long range transport from these hot spots gives rise to wide spread plumes over the adjacent oceans. Such a pattern of regionally concentrated surface dimming and atmospheric solar heating, accompanied by wide spread dimming over the oceans, gives rise to large regional effects. Only during the last decade, we have begun to comprehend the surprisingly large regional impacts. The large north-south gradient in the ABC dimming has altered the north-south gradients in sea surface temperatures, which in turn has been shown by models to decrease rainfall over the continents. The uncertainties in our understanding of the ABC effects are large, but we are discovering new ways in which human activities are changing the climate and the environment.

Ramanathan, V.

2007-12-01

237

Tectonic implications of radiogenic noble gases in planetary atmospheres  

NASA Astrophysics Data System (ADS)

Measurements of the quantity of noble gases in the atmospheres of the terrestrial planets and the Moon provide important constraints on the dynamics of atmosphere formation and loss. In this paper the authors are primarily concerned with the implications of long-lived radiogenic isotopes on the tectonics of planetary interiors. They focus their attention on the systematics of 4He and 40Ar that are produced by the principal heat-producing isotopes 238U, 235U, 232Th, and 40K. The efficiency of escape of these noble gas isotopes can provide insights into both transport mechanisms and internal processes.

Turcotte, D. L.; Schubert, G.

1988-04-01

238

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

239

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

SciTech Connect

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.

LR Roeder

2008-12-01

240

Radiative heating in contrail cirrus  

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

241

String gases in the early universe  

NASA Astrophysics Data System (ADS)

In this thesis we examine the classical and quantum effects of string gases on the evolution of the universe. In particular, we find that at early times string gases can explain both the dimensionality and the observed isotropy of our visible universe. Moreover, considering the backreaction of string gases on cosmological moduli, such as the radion, we find a novel stabilization mechanism. We also examine the role of strings at later times in the cosmic evolution, focusing on the issue of inhomogeneities and the dilution of the gas as the expansion continues. Some challenges will arise, but solutions are found by considering quantum production of strings. We also find that remnant strings in the extra dimensions may provide a new solution to the cold dark matter problem.

Watson, Gary Scott

242

Where do California's greenhouse gases come from?  

ScienceCinema

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.

Fischer, Marc

2013-05-29

243

Methanol production from fermentor off-gases  

NASA Astrophysics Data System (ADS)

The off gases from an acetone butanol fermentation facility are composed mainly of CO2 and H2. Such a gas stream is an ideal candidate as a feed to a methanol synthesis plant utilizing modern technology recently developed and known as the CDH-methanol process. A detailed economic analysis for the incremental cost of a methanol synthesis plant utilizing the off gases from an acetone butanol fermentation indicates a profitable rate of return of 25 to 30% under the most likely production conditions. Bench scale studies at different fermentor mixing rates indicate that the volume of gases released during the fermentation is a strong function of the agitation rate and point to a potential interaction between the volume of H2 evolved and the levels of butanol present in the final fermented broth. Such interaction may require establishing optimum operating conditions for an integrated butanol fermentation methanol synthesis plant.

Dale, B. E.; Moreira, A. R.

244

Bioprocessing of organic gases in waste air  

SciTech Connect

Natural porous media (soils, compost, peat, wood bark chips) in biofilters effectively, safely, and inexpensively remove organic gases from air by adsorbing then and oxidizing them to CO{sub 2}. The sorption capacities of the media are low: their effectiveness is due to oxidation by the active microbial population which disposes the gas and continuously regenerates the sorption capacity. O-, N-, and S-containing organic gases generally oxidize rapidly and {>=}95% removal efficiency is routine. Aromatic and halogenated organic gases oxidize slowly and require correspondingly larger biofilter beds and reaction times to achieve high removal efficiencies. Installation costs of biofilters vary widely, operating costs are low because no fuel or oxidant is required, and no secondary pollution is created.

Bohn, H.L. [Univ. of Arizona, Tucson, AZ (United States)

1993-12-31

245

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

SciTech Connect

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

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

1993-11-01

246

Ultracold Lattice Gases with Periodically Modulated Interactions  

NASA Astrophysics Data System (ADS)

We show that a time-dependent magnetic field inducing a periodically modulated scattering length may lead to interesting novel scenarios for cold gases in optical lattices, characterized by a nonlinear hopping depending on the number difference at neighboring sites. We discuss the rich physics introduced by this hopping, including pair superfluidity, exactly defect-free Mott-insulator states for finite hopping, and pure holon and doublon superfluids. We also address experimental detection, showing that the introduced nonlinear hopping may lead in harmonically trapped gases to abrupt drops in the density profile marking the interface between different superfluid regions.

Rapp, Ákos; Deng, Xiaolong; Santos, Luis

2012-11-01

247

Measuring Viscosities of Gases at Atmospheric Pressure  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

248

Xenon and other noble gases in shergottites  

NASA Astrophysics Data System (ADS)

The isotopic composition of the xenon component trapped in EETA 79001's lithologies B and C has been determined, and other noble gases were measured in some samples. The Xe component was found to have light isotope ratios indistinguishable from those of the terrestrial atmosphere. The trapped component has a Xe-129/Xe-132 ratio of about 2.4, and is enhanced in Xe-134 and Xe-136 relative to the terrestrial atmosphere or the average carbonaceous chondrite. Similarities between values for Ar-40/Ar-36, Xe-129/Xe-132, and N-15/N-14 and the corresponding Martian atmospheric values suggest Martian origin of the trapped gases.

Swindle, T. D.; Caffee, M. W.; Hohenberg, C. M.

1986-06-01

249

Stationary light in cold atomic gases  

E-print Network

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

Gor Nikoghosyan; Michael Fleischhauer

2009-09-16

250

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...

251

Radiation Induced Osmosis  

NASA Astrophysics Data System (ADS)

Pressure transients are observed in absorbing gases at low pressure in a non-resonant spectrophone. At very low pressure (transition saturated) the transient is negative on irradiation. Interpretation is given in terms of thermodynamics of laser driven systems. The local value of the partition function depends exponentially on the incident radiation's intensity. The observed depression on irradiation is the consequence of the law of mass action applied to inhomogeneously irradiated systems.

de Hemptinne, X.

1985-03-01

252

Direct radiative forcing of anthropogenic aerosols over oceans from satellite observations  

NASA Astrophysics Data System (ADS)

Anthropogenic aerosols play an important role in the atmospheric energy balance. Anthropogenic aerosol optical depth (AOD) and its accompanying shortwave radiative forcing (RF) are usually simulated by numerical models. Recently, with the development of space-borne instruments and sophisticated retrieval algorithms, it has become possible to estimate aerosol radiative forcing based on satellite observations. In this study, we have estimated shortwave direct radiative forcing due to anthropogenic aerosols over oceans in all-sky conditions by combining clouds and the Single Scanner Footprint data of the Clouds and Earth's Radiant Energy System (CERES/SSF) experiment, which provide measurements of upward shortwave fluxes at the top of atmosphere, with Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol and cloud products. We found that globally averaged aerosol radiative forcing over oceans in the clear-sky conditions and all-sky conditions were -1.03±0.48 W m-2 and -0.34 ±0.16 W m-2, respectively. Direct radiative forcing by anthropogenic aerosols shows large regional and seasonal variations. In some regions and in particular seasons, the magnitude of direct forcing by anthropogenic aerosols can be comparable to the forcing of greenhouse gases. However, it shows that aerosols caused the cooling effect, rather than warming effect from global scale, which is different from greenhouse gases.

Chen, Lin; Shi, Guangyu; Qin, Shiguang; Yang, Su; Zhang, Peng

2011-07-01

253

A Photoionization Detector for Gases and Vapours  

Microsoft Academic Search

SENSITIVE ionization methods for the measurement of low gas and vapour concentration require the ionization of the test gas or vapour under conditions where an inert carrier gas is unionized. Such methods as the ionization of carbon compounds in a hydrogen flame1 and the reaction between gases and vapours and rare gas metastables2 are well established and successful for this

J. E. Lovelock

1960-01-01

254

Elimination of gases and contamination from water  

NASA Technical Reports Server (NTRS)

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.

Buck, A. P.

1970-01-01

255

Electron-Atom Collisions in Gases  

ERIC Educational Resources Information Center

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

Kraftmakher, Yaakov

2013-01-01

256

Thorsten Poschel, Stefan Luding (Eds.) Granular Gases  

E-print Network

4. The rings around the outer planets of the Solar system have been intensively studied { and continue to do so. In a strict de#12;nition, \\Granular Gases" are dilute granular systems, i.e., many as a many particle system requires comprehensive understanding of the details of collisions of only two

Luding, Stefan

257

Fullerenes and the Nature of Planetary Gases  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

258

Prediction of friction coefficients for gases  

NASA Technical Reports Server (NTRS)

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

Taylor, M. F.

1969-01-01

259

Kerr Constants of the Hydrogen Halide Gases  

Microsoft Academic Search

ON the basis of a recent note dealing with the polarization ellipsoids of the hydrogen halide gases1, it becomes possible to calculate their Kerr constants (Na-D line, 20° C, 760 mm.), numbers which should be directly capable of experimental verification.

C. H. Douglas Clark; E. C. Humphries

1936-01-01

260

40 CFR 90.312 - Analytical gases.  

Code of Federal Regulations, 2011 CFR

...Provisions § 90.312 Analytical gases. (a) The shelf life of a calibration gas may not be exceeded. The expiration date...balance oxygen. (e) Fuel for the hydrocarbon flame ionization detector (HC-FID) must be a blend of 40 ±two percent...

2011-07-01

261

40 CFR 90.312 - Analytical gases.  

...Provisions § 90.312 Analytical gases. (a) The shelf life of a calibration gas may not be exceeded. The expiration date...balance oxygen. (e) Fuel for the hydrocarbon flame ionization detector (HC-FID) must be a blend of 40 ±two percent...

2014-07-01

262

40 CFR 91.312 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

...Provisions § 91.312 Analytical gases. (a) The shelf life of a calibration gas may not be exceeded. Record the expiration...balance oxygen. (e) Fuel for the hydrocarbon flame ionization detector (HC-FID) must be a blend of 40±2 percent...

2010-07-01

263

40 CFR 91.312 - Analytical gases.  

...Provisions § 91.312 Analytical gases. (a) The shelf life of a calibration gas may not be exceeded. Record the expiration...balance oxygen. (e) Fuel for the hydrocarbon flame ionization detector (HC-FID) must be a blend of 40±2 percent...

2014-07-01

264

40 CFR 90.312 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...Provisions § 90.312 Analytical gases. (a) The shelf life of a calibration gas may not be exceeded. The expiration date...balance oxygen. (e) Fuel for the hydrocarbon flame ionization detector (HC-FID) must be a blend of 40 ±two percent...

2013-07-01

265

40 CFR 90.312 - Analytical gases.  

Code of Federal Regulations, 2012 CFR

...Provisions § 90.312 Analytical gases. (a) The shelf life of a calibration gas may not be exceeded. The expiration date...balance oxygen. (e) Fuel for the hydrocarbon flame ionization detector (HC-FID) must be a blend of 40 ±two percent...

2012-07-01

266

40 CFR 91.312 - Analytical gases.  

Code of Federal Regulations, 2012 CFR

...Provisions § 91.312 Analytical gases. (a) The shelf life of a calibration gas may not be exceeded. Record the expiration...balance oxygen. (e) Fuel for the hydrocarbon flame ionization detector (HC-FID) must be a blend of 40±2 percent...

2012-07-01

267

40 CFR 91.312 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...Provisions § 91.312 Analytical gases. (a) The shelf life of a calibration gas may not be exceeded. Record the expiration...balance oxygen. (e) Fuel for the hydrocarbon flame ionization detector (HC-FID) must be a blend of 40±2 percent...

2013-07-01

268

40 CFR 91.312 - Analytical gases.  

Code of Federal Regulations, 2011 CFR

...Provisions § 91.312 Analytical gases. (a) The shelf life of a calibration gas may not be exceeded. Record the expiration...balance oxygen. (e) Fuel for the hydrocarbon flame ionization detector (HC-FID) must be a blend of 40±2 percent...

2011-07-01

269

Emission factors of hydrocarbons, halocarbons, trace gases and particles from biomass burning in Brazil  

Microsoft Academic Search

Airborne measurements of the emissions of gases and particles from 19 individual forest, cerrado, and pasture fires in Brazil were obtained during the Smoke, Clouds, and Radiation-Brazil (SCAR-B) study in August-September 1995. Emission factors were determined for a number of major and minor gaseous and particulate species, including carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxides, methane, nonmethane hydrocarbons, halocarbons,

Ronald J. Ferek; Jeffrey S. Reid; Peter V. Hobbs; Donald R. Blake; Catherine Liousse

1998-01-01

270

APPLICATIONS OF LASERS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Optical breakdown thresholds of rare gases Xe and Kr in a wide frequency range  

NASA Astrophysics Data System (ADS)

An experimental determination was made of the optical breakdown thresholds of rare gases Xe and Kr in a wide (including ultraviolet) range of wavelengths and radiation intensities. Measurements were made at pressures of 200 and 760 Torr using the first to the fourth harmonics of single-mode frequency-stabilized neodymium laser radiation.

Alferov, S. V.; Nazarkin, A. V.; Norinski?, L. V.; Rogov, V. S.; Smetanin, Igor V.

1992-06-01

271

Changes in the Seasonality of Tropical Precipitation in Response to Greenhouse Gases: Local and Remote Forcings  

Microsoft Academic Search

When forced with increasing greenhouse gases, all of the CMIP3 models project a delay of the annual cycle of global precipitation and SST. This global phase shift has important regional manifestations, that are quite robust across the CMIP3 ensemble. At regional scales, though, rainfall and temperature anomalies may be more complex than a simple shift and, in places, are better

M. Biasutti; A. H. Sobel; D. S. Battisti

2009-01-01

272

Ozone-depleting substances and the greenhouse gases HFCs, PFCs and  

E-print Network

Ozone-depleting substances and the greenhouse gases HFCs, PFCs and SF6 Danish consumption contribution to the debate on environmental policy in Denmark. #12;3 Contents 1 SUMMARY 5 1.1 OZONE OZONE-DEPLETING SUBSTANCES 18 3.1 IMPORTS AND EXPORTS 18 3.1.1 CFCs 18 3.1.2 Tetrachloromethane 19 3

273

49 CFR 173.302a - Additional requirements for shipment of nonliquefied (permanent) compressed gases in...  

Code of Federal Regulations, 2010 CFR

...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging ...nonliquefied (permanent) compressed gases in specification cylinders. ...requirements. Nonliquefied compressed gases (except gas in solution) for which...

2010-10-01

274

Molecular simulation of separation of CO from flue gases in Cu-BTC metal-organic framework  

Microsoft Academic Search

In this work, a computational study was performed on the adsorption separation of CO from flue gases (mixtures of CO\\/N\\/O) in Cu-BTC metal-organic framework (MOF) to investigate the applicability of MOFs to this important industrial system. The computational results showed that Cu-BTC is a promising material for separation of CO from flue gases, and the macroscopic separation behaviors of the

Qingyuan Yang; Chunyu Xue; Chongli Zhong; Jian-Feng Chen

2007-01-01

275

40 CFR 86.1214-85 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

... false Analytical gases. 86.1214-85...CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL...Gasoline-Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas-Fueled and Methanol-Fueled...1214-85 Analytical gases. (a) Analyzer...

2010-07-01

276

49 CFR 173.306 - Limited quantities of compressed gases.  

Code of Federal Regulations, 2010 CFR

...transported as non-pressurized gas when its pressure corresponding...ii) Non-pressurized gases, toxic (or toxic and...by heat, and compressed gas or gases. Plastic containers must...or emulsified compressed gas. The capacity of...

2010-10-01

277

40 CFR 600.108-08 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

... false Analytical gases. 600.108-08...POLICY FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF MOTOR VEHICLES ...Carbon-Related Exhaust Emission Test Procedures § 600.108-08 Analytical gases. The...

2013-07-01

278

40 CFR 600.108-08 - Analytical gases.  

Code of Federal Regulations, 2012 CFR

... false Analytical gases. 600.108-08...POLICY FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF MOTOR VEHICLES ...Carbon-Related Exhaust Emission Test Procedures § 600.108-08 Analytical gases. The...

2012-07-01

279

Method for enhancing microbial utilization rates of gases using perfluorocarbons  

DOEpatents

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.

Turick, C.E.

1997-06-10

280

Method for enhancing microbial utilization rates of gases using perfluorocarbons  

DOEpatents

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.

Turick, Charles E. (Idaho Falls, ID)

1997-01-01

281

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

282

Thermodynamics of Quantum Gases for the Entire Range of Temperature  

ERIC Educational Resources Information Center

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

Biswas, Shyamal; Jana, Debnarayan

2012-01-01

283

Apparatus for recovery of heat from exhaust gases of dryer  

Microsoft Academic Search

Apparatus and method are disclosed for recovery of heat from exhaust gases of dryers and return of heat to the dryer system. Fresh air is drawn through a plurality of tubes in heat exchange relation to heated exhaust gases and introduced into the drying system without intermingling of contaminated exhaust gases with the heated fresh air. The apparatus and method

Winstel

1977-01-01

284

Gases of mud volcanoes in the Copper River Basin, Alaska  

Microsoft Academic Search

The gases emitted from mud volcanoes in the Copper River Basin of Alaska fall into two distinct types which are not mixed during vertical migration. The gases in the eastern volcanoes are nearly pure carbon dioxide, whereas the western ones contain methane and nitrogen and almost no carbon dioxide. Chemical and carbon isotopic compositions suggest the carbon dioxide rich gases

Robert H. Reitsema

1979-01-01

285

Supercontinuum generation in gases: A high order nonlinear optics phenomenon  

SciTech Connect

The recent development of high power, ultrashort pulse sources has created renewed interest in the interaction between intense laser radiation and free atoms and molecules. Not only is it feasible to apply laser fields that approach, or exceed, the strength of the atomic field as seen by the outer electrons, but it is also possible to apply these fields nonadiabatically using ultrashort pulses. Until now, experiments have been restricted to isolated atoms. However, because the theories of nonlinear optics and multiphoton ionization are so interrelated, we should expect these new phenomena to have optical signatures. In addition to their intrinsic interest, nonlinear optics experiments can add a new perspective for judging emerging theories of high intensity laser processes. Clearly, there is a new class of experiments to be performed using ultrahigh power, ultrashort pulses. We describe an experiment performed in high pressure gases with a 2 psec or 70 fsec 0.6 {mu}m pulse focused to a peak intensity of I {approx lt} 10{sup 13} W/cm{sup 2}. The maximum intensity exceeds that in which multiphoton ionization is observed in longer pulse experiments in Xe using either 1.06 {mu}m or 0.53 {mu}m radiation. It is approximately the intensity at which tunnel ionization is observed with nanosecond 10 {mu}m pulses in very low pressure Xe. Furthermore, at such intensities in 0.53 {mu}m and 1.06 {mu}m experiments, high energy electrons are observed from Xe.

Corkum, P.B.; Rolland, C. (National Research Council of Canada, Ottawa, ON (Canada)); Srinivasan-Rao, T. (Brookhaven National Lab., Upton, NY (USA))

1986-01-01

286

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

NASA Technical Reports Server (NTRS)

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

Gustincic, J. J. (inventor)

1981-01-01

287

Underground Nuclear Explosions and Release of Radioactive Noble Gases  

NASA Astrophysics Data System (ADS)

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.

Dubasov, Yuri V.

2010-05-01

288

Degenerate quantum gases with spin–orbit coupling: a review  

NASA Astrophysics Data System (ADS)

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

Zhai, Hui

2015-02-01

289

Solubilities of nitrogen and noble gases in basalt melt  

NASA Astrophysics Data System (ADS)

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.

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

290

Solubilities of nitrogen and noble gases in basalt melt  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

291

In Situ Imaging of Atomic Quantum Gases  

NASA Astrophysics Data System (ADS)

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

Hung, Chen-Lung; Chin, Cheng

2015-09-01

292

Sampling and analysis of gases and vapors  

SciTech Connect

Techniques which were available to the industrial hygienist for evaluating exposures to gases and vapors in the work environment were described. The applications and limitations of several sampling media and techniques were presented. General sampling considerations discussed included sampling strategies, and operational limits of sampling and analysis. Sampling media for gases and vapors included solid sorbents, activated charcoal, silica gel, porous polymers, tenax, proapaks, chromosorbs, XAD resins, other solid sorbents, multistage air sampling tubes, liquid absorbers, passive samplers, and flexible plastic bags/partially evacuated rigid containers. Desorption of contaminants and collection efficiency of solid sorbents were also discussed. Analytical techniques considered include gas chromatography, flame ionization detector, nitrogen/phosphorus detector, flame photometric detector, electron capture detector, hall conductivity detector, thermal conductivity detector, photoionization detector, high performance liquid chromatography, gas chromatography/mass spectrometry, volumetric methods, and ion chromatography. Quality assurance was discussed.

Coffman, M.A.; Singh, J.

1991-08-01

293

Unsteady shock waves in inhomogeneous gases  

NASA Astrophysics Data System (ADS)

The interaction between a propagating shock wave and the diffusion layer between two gases is investigated theoretically and experimentally. Equations describing the reflection and amplification or absorption of a shock at a contact surface are combined with expressions describing diffusion at the gas-gas interface, and the resulting system is modified by the technique of Chisnell (1955) to obtain an approximate solution which is compatible with finite-difference numerical-computation techniques. Simulation results are presented graphically for combinations of gases with different molecular masses and degrees of freedom and shown to be in agreement with those obtained experimentally in a shock tube of overall length 7.5 m using pressure probes, film thermometers, and schlieren photography. It is found that the waves reflected in the diffusion zone are reflected again as they propagate upstream; this multiple reflection affects the shock wave even outside the diffusion zone and partially compensates the pressure differential.

Weber, G.

1983-01-01

294

Quantum fluctuations in dipolar Bose gases  

SciTech Connect

We investigate the influence of quantum fluctuations upon dipolar Bose gases by means of the Bogoliubov-de Gennes theory. Thereby, we make use of the local density approximation to evaluate the dipolar exchange interaction between the condensate and the excited particles. This allows to obtain the Bogoliubov spectrum analytically in the limit of large particle numbers. After discussing the condensate depletion and the ground-state energy correction, we derive quantum-corrected equations of motion for harmonically trapped dipolar Bose gases by using superfluid hydrodynamics. These equations are subsequently applied to analyze the equilibrium configuration, the low-lying oscillation frequencies, and the time-of-flight dynamics. We find that both atomic magnetic and molecular electric dipolar systems offer promising scenarios for detecting beyond mean-field effects.

Lima, Aristeu R. P.; Pelster, Axel [Institut fuer Theoretische Physik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin (Germany); Fachbereich Physik, Universitaet Duisburg-Essen, Lotharstrasse 1, D-47048 Duisburg (Germany)

2011-10-15

295

Biofilters remove VOCs from stack gases  

SciTech Connect

Weyerhaeuser's strandboard plant in Grayling, Mich., is using biofiltration to remove volatile organic compounds (VOCs) at the site. Primary constituents in the Weyerhaeuser stack gases are alcohols, aldehydes, organic acids, benzene and toluene. The alternative to biofiltration is incineration, but because the concentration of VOCs in the stack gases is so dilute, natural gas would be required. Incineration would be costly, and could introduce pollution problems by generating excess carbon dioxide (CO[sub 2]) and possibly nitrogen oxides. Two pilot biofilters, each about 20ft by 100ft in area, with 4-ft thick media of bark and ground trim ends, are using naturally occurring bacteria to destroy VOCs emanating from a wood panel press and a wood flake dryer. The press offgas biofilter, activated February 1993, had risen to 93% efficiency in removing VOCs by mid-May. The flake dryer exhaust biofilter, placed in service in April, already was more than 80% efficient.

Not Available

1993-10-01

296

Anesthetic gases and occupationally exposed workers.  

PubMed

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

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

2014-01-01

297

Interferometric Monitor for Greenhouse Gases (IMG)  

NASA Astrophysics Data System (ADS)

A satellite borne FTIR called IMG(Interferometric Monitor for Greenhouse Gases) was developed by JAROS (Japan Resources Observation System Organization) deputed by MITI (Ministry of International Trade and Industry). It was installed on ADEOS (Advanced Earth Observing Satellite) which was launched on Aug. 1966 by NASDA (National Space Development Agency of Japan). IMG is a very high spectral resolution (0.1cm-1) spectrometer that covers a wide range of infrared spectrum (3.3 - 15 ?m). With these features, IMG could detect and monitor spatial and vertical distribution of greenhouse effect gases such as CO2, CH4, 03, etc. over the entire Earth. Unfortunately, ADEOS stopped its operation on 30, June 1997, but about 8 months of data have been collected. IMG sensor characteristics and some of the initial scientific results are described

Shimoda, H.; Ogawa, T.

298

Method for introduction of gases into microspheres  

DOEpatents

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.

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

1981-01-01

299

Noble Gases in the Chelyabinsk Meteorites  

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

300

Apparatus for sampling particulates in gases  

NASA Technical Reports Server (NTRS)

A device for sampling particulates in gases is described. The device is used to obtain samples of the upper atmosphere. The equipment used a common source of gas pressure to provide the driving gas of an air ejector pump. The sample collection cylinder has many slit impactors running longitudinally on the outer surface of a cylinder and terminating just short of each end of the cylinder.

Wood, R. C. (inventor)

1973-01-01

301

Thermodynamics of dilute gases in shear flow  

NASA Astrophysics Data System (ADS)

We consider the effect of shear and normal viscous pressures on the non-equilibrium entropy of ideal gases in Couette flow. These results extend the previous ones (Bidar et al., Physica A 233 (1996) 163), where normal pressure effects were ignored. Furthermore, we analyze the non-equilibrium contributions to the chemical potential, which may be useful in the analysis of shear-induced effects on colligative properties and chemical equilibrium.

Jou, D.; Criado-Sancho, M.

2001-03-01

302

Chemisorption of Electronegative Gases on Refractory Metals  

Microsoft Academic Search

This experiment is a study of some aspects of the chemisorption of diatomic gases on metal surfaces for temperatures of 1800°—2200°K and pressures of 4.0–6.0×10?6 torr. The systems studied were chlorine and carbon on tungsten where the carbon was present as a contaminant, and chlorine and hydrogen chloride on hafnium. We observed the flux of atomic negative ions formed from

Marion L. Shaw; N. P. Carleton

1966-01-01

303

Condensation cleaning of particulate laden gases  

SciTech Connect

Particulate laden gas, especially those gases carrying particulates having a size in the micron or submicron range, are removed by humidifying the gas with water and thereafter subjecting the gas to indirect contact heat exchange sufficient to provide an energy transfer for water vapor condensation of at least 5 horsepower per 1000 cfm. Heat exchange is accomlished by passing the gas downwardly through an exchange element having smooth and vertical gas passages of a relatively large dimension.

Devries, E.

1981-08-18

304

On weak shock diffraction in real gases  

E-print Network

Asymptotic solutions are obtained for the two-dimensional Euler system for real gases with appropriate boundary conditions which describe the diffraction of a weak shock at a right-angled wedge; the real gas effects are characterized by a van der Waals type equation of state. The behavior of the flow configuration influenced by the real gas effects, that includes the local structure near a singular point, is studied in detail.

Neelam Gupta; V. D. Sharma

2014-05-17

305

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

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.

Prather, Michael J. [UCI

2014-11-07

306

Treatment of flue gas containing noxious gases  

SciTech Connect

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.

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

1987-07-21

307

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

308

Distribution and origin of dissolved gases of groundwaters at Las Cañadas aquifer, Tenerife, Canary Islands  

NASA Astrophysics Data System (ADS)

Volcanic aquifers commonly trap an important fraction of the main soluble components of fluids released from volcanic-hydrothermal system (CO2, SO2, H2S, HCl, HF, etc.). In particular, the interactions between volcanic gases and volcanic aquifers have been studied through hydrogeochemical parameters, as major and minor ions contents and dissolved gases in groundwaters. In the context of hydrogeochemical studies applied to active volcanic areas, studies of dissolved gases species in groundwater could be a useful tool to better understand the subsurface processes as gas-water-rock interaction or to strengthen the geochemical seismic-volcanic surveillance programs. In this work, we report the results of the geochemical characterization of dissolved gases (N2, O2, Ar, CO2, CH4, CO, H2, He, 222Rn, ?13CTDIC) in 96 groundwater samples from Las Cañadas aquifer (around Teide volcano) between May and October, 2006. The main aims of this work are: (1) to determine the background level of magmatic gas input in the aquifer during quiescent periods, (2) to better define the origin of dissolved gases in Las Cañadas aquifer, specially CO2, (3) to evaluate the gas-water-rock interaction processes occurring at depth, and (4) to delineate high permeable pathway of upward migration of volcanic-hydrothermal gases. In general, the dissolved gas phase in groundwaters of Las Cañadas aquifer is relatively enriched in endogenous gases (CO2, He and H2) while it is relatively depleted in atmospheric gases (N2, O2 and Ar). N2-O2-CO2 triangular diagram shows that dissolved gases in most of analyzed groundwater are variable mixtures of CO2-rich fluids from the volcanic-hydrothermal system (as represent the Teide fumaroles) with dissolved air. The relatively high N2/O2 ratio in some groundwater compared to the air saturated water suggests an O2 consumption during gas-water-rock interactions occurring at depth. Spatial distribution maps show anomalous concentration of 222Rn CH4, H2 and CO2 dissolved in groundwater at the westernmost area of Las Cañadas aquifer, which is in good spatial correlation with geophysical and geochemical anomalies related to 2004-2005 seismic-volcanic unrest at Tenerife Island. Determinations of ?13C values in the total dissolved inorganic carbon (TDIC) in groundwater in Las Cañadas aquifer ranging from -5 to +5 (‰ vs PDB). This result was explained by isotopic fractionation of either volcanic-hydrothermal CO2 partially dissolved in groundwater or due to precipitation of CaCO3 and CO2 degassing related to silicate hydrolysis dissolving Ca2+.

Marrero, R.; Melian, G.; Padron, E.; Sortino, F.; Hernandez Perez, P. A.; Lopez, D. L.; Perez, N.

2009-12-01

309

Chemistry of Sodium, Potassium, and Chlorine in Volcanic Gases on Io  

NASA Astrophysics Data System (ADS)

We used thermochemical equilibrium calculations in the O-S-Na-K-Cl-H system to model the speciation of volcanic gases emitted from high-temperature (1000-2000 K) silicate magmas on Io. The effects of temperature, pressure, and bulk composition of the gases are explored. The bulk compositions are based on atomic ratios observed in Io's plasma torus and extended atmosphere, and from chondritic abundances. The results show that chlorides of Na and K are the major Cl gases, NaCl, Na, and (NaCl) 2 are the major Na gases, and KCl, (KCl) 2, and K are the major K gases for systems with (Na+K)/Cl>1. The abundances of Na, K, and Cl gases change dramatically at (Na+K)/Cl=1. As the (Na+K)/Cl ratio decreases below unity, which is possible for lower temperature volcanic vents, the major Cl gases change to Cl 2, Cl, S 2Cl, and SCl 2. The results show that abundances of H-bearing gases are insignificant for plausible hydrogen abundances in Io. Higher temperatures and lower pressures increase the abundances of monatomic Na and K. Sodium, K, and Cl compounds condense as Na 2S (at higher temperatures and lower O/S ratios), Na 2SO 4 (at lower temperatures and higher O/S ratios), and NaCl and KCl. Under some conditions, Na 2SO 4 and Na 2S condense simultaneously. These condensates can form coatings on silicate ash particles in the vicinity of volcanic vents. Condensation temperatures decrease as pressure decreases, and condensation is not favored by low-pressure volcanic vents. Silicate magmas, especially alkaline ultrabasic magmas may be important sources of S, alkalis, and Cl on Io. Our predictions agree with spectral absorption features indicating that sodium sulfate and/or sodium sulfide may be present in red deposits on Io's surface. The two major sources of Na, K, and Cl in the plasma torus are sputtering from solid Na 2S/Na 2SO 4/chloride surface condensates and ionization of alkali chloride and monatomic alkali gases that could be present in volcanic plumes and Io's volcanic atmosphere.

Fegley, Bruce; Zolotov, Mikhail Yu.

2000-11-01

310

RADIATION DETECTORS  

Microsoft Academic Search

Three new and important lines of development in nuclear radiation ; detection and measurement are presented. Two of these developments, spark ; chambers and image-intensifier\\/ luminescent-chamber systems, enable pictures or ; other records of nuclear particle tracks to be obtained with a much higher degree ; of time resolution than is possible with existing techniques, e g., with cloud ;

W. Abson

1962-01-01

311

Emissions Of Greenhouse Gases From Rice Agriculture  

SciTech Connect

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.

M. Aslam K. Khalil

2009-07-16

312

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

SciTech Connect

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

Friedrich, Elena, E-mail: Friedriche@ukzn.ac.z [University of KwaZulu-Natal, CRECHE, School of Civil Engineering, Surveying and Construction, Howard College Campus, Durban (South Africa); Trois, Cristina [University of KwaZulu-Natal, CRECHE, School of Civil Engineering, Surveying and Construction, Howard College Campus, Durban (South Africa)

2010-11-15

313

Photosensitive dopants for liquid noble gases  

DOEpatents

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.

Anderson, David F. (Wheaton, IL)

1988-01-01

314

Diurnal characteristics of surface level O3 and other important trace gases in New England  

Microsoft Academic Search

Data obtained from spring 2001 to summer 2003 in New England by the Atmospheric Investigation, Regional Modeling, Analysis and Prediction (AIRMAP) program were used to document the diurnal characteristics of O3, CO2, NO, and during selected intervals hydrocarbon and oxygenated species. The diurnal cycles of O3 and oxygenated species showed a monotonic rise in mixing ratio following sunrise (replenishment) that

Robert Talbot; Huiting Mao; Barkley Sive

2005-01-01

315

Sensory Detection and Responses to Toxic Gases  

PubMed Central

The inhalation of reactive gases and vapors can lead to severe damage of the airways and lung, compromising the function of the respiratory system. Exposures to oxidizing, electrophilic, acidic, or basic gases frequently occur in occupational and ambient environments. Corrosive gases and vapors such as chlorine, phosgene, and chloropicrin were used as warfare agents and in terrorist acts. Chemical airway exposures are detected by the olfactory, gustatory, and nociceptive sensory systems that initiate protective physiological and behavioral responses. This review focuses on the role of airway nociceptive sensory neurons in chemical sensing and discusses the recent discovery of neuronal receptors for reactive chemicals. Using physiological, imaging, and genetic approaches, Transient Receptor Potential (TRP) ion channels in sensory neurons were shown to respond to a wide range of noxious chemical stimuli, initiating pain, respiratory depression, cough, glandular secretions, and other protective responses. TRPA1, a TRP ion channel expressed in chemosensory C-fibers, is activated by almost all oxidizing and electrophilic chemicals, including chlorine, acrolein, tear gas agents, and methyl isocyanate, the highly noxious chemical released in the Bhopal disaster. Chemicals likely activate TRPA1 through covalent protein modification. Animal studies using TRPA1 antagonists or TRPA1-deficient mice confirmed the role of TRPA1 in chemically induced respiratory reflexes, pain, and inflammation in vivo. New research shows that sensory neurons are not merely passive sensors of chemical exposures. Sensory channels such as TRPA1 are essential for maintenance of airway inflammation in asthma and may contribute to the progression of airway injury following high-level chemical exposures. PMID:20601631

Bessac, Bret F.; Jordt, Sven-Eric

2010-01-01

316

Adsorption of Gases on Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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

Mbaye, Mamadou Thiao

317

Photoconduction in GaSe thin films  

Microsoft Academic Search

Photoconduction in GaSe thin films has been measured in the spectral energy range 1?0 eV-3?2 eV. Extrapolation of the linear region of the spectral response curve gives 1?67 eV as the energy gap of the as-grown films. Measurements have been made in the temperature- range 77 K–300 K and the activation energy for the photo-conductive processes is found to be 0?19 eV.

MOHAMMAD KHALID ANIS; MOHAMMAD YAR ZAHEER; FATEH MOHAMMAD NAZAR

1981-01-01

318

Excitation and quenching of detonation in gases  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

319

Dense gases for extraction and refining  

SciTech Connect

Procedures for extracting or refining sensitive substances using dense gases have been developed for numerous purposes. Applications have been tested on the laboratory or pilot plant scales and shown to be mostly economical. Uses as varied as the non-aggressive extraction of spice, extraction of polymers, refining of spent oil, pyrolysis/extraction of wood and liquefaction of coal show the extremely wide range of application. The book reviews the present state of development and features examples of application of this new technique.

Stahl, E.; Quirin, K.W.; Gerard, D.

1987-01-01

320

Heat conduction in relativistic neutral gases revisited  

E-print Network

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

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

2010-09-30

321

Neutrino oscillations in dense neutrino gases  

NASA Astrophysics Data System (ADS)

We consider oscillations of neutrinos under conditions in which the neutrino density is sufficiently large that neutrino-neutrino interactions cannot be neglected. A formalism is developed to treat this highly nonlinear system. Numerical analysis reveals a rich array of phenomena. In certain gases, a self-induced Mikheyev-Smirnov-Wolfenstein effect occurs in which electron neutrinos are resonantly converted into muon neutrinos. In another relatively low-density gas, an unexpected parametric resonant conversion takes place. Finally, neutrino-neutrino interactions maintain coherence in one system for which a priori one expected decoherence.

Samuel, Stuart

1993-08-01

322

Efficieny handling effluent gases through chemical scrubbing  

NASA Astrophysics Data System (ADS)

This paper is presented as an information source for efficiencies of chemical scrubbing. In it, we will discuss the specific problems of scrubbing silane, disilane, diborane, phosphine, hydrogen selenide and arsine. We will explain the scrubber dynamics, gases and flow rates used along with liquid mediums. The equipment and procedures used for testing, as well as the determination of the results, will be discussed. We intend to give examples of possible reactions and documentation of our efficiencies. Installation and maintenance will be touched, as well as our experiments into accidental catastrophic releases. From all of this we will derive conclusions as to the best possible means of wet chemical scrubbing.

Herman, Tim; Soden, Scott

1988-07-01

323

Method for detecting trace impurities in gases  

DOEpatents

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.

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

324

Transonic Lifting Flows of Pressurized Gases  

NASA Astrophysics Data System (ADS)

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.

Cramer, Mark; Morrison, Michael

1997-11-01

325

Catalytic Generation of Lift Gases for Balloons  

NASA Technical Reports Server (NTRS)

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

Zubrin, Robert; Berggren, Mark

2011-01-01

326

Remote Sensing of Greenhouse Gases and Their Sources and Sinks  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

327

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

SciTech Connect

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.

Cushman, R.M.

2003-08-28

328

Photosensitive dopants for liquid noble gases  

SciTech Connect

A method of detecting radiation with an ionization detector is described comprising the steps of: dissolving a photosensitive dopant in a noble gas; liquifying the doped noble gas; placing the doped liquified noble gas in the ionization detector; introducing radiation to be detected into the ionization detector; collecting free ions in the ionization detector; and counting the free ions collected within the ionization detector.

Anderson, D.F.

1988-03-22

329

Aerothermodynamic radiation studies  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

330

Habitat: importance, destruction, & Habitat: importance, destruction, &  

E-print Network

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

Limburg, Karin E.

331

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.

332

Emissions of sulfur gases from wetlands  

NASA Technical Reports Server (NTRS)

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

Hines, Mark E.

1992-01-01

333

[Desulfurization of fuel gases]. Executive summary  

SciTech Connect

The objective of this work was to demonstrate that solid solutions of cerium oxide (CeO{sub 2}) and other altervalent oxides (doped CeO{sub 2}) were capable of removing more H{sub 2}S from fuel gases than Ceo{sub 2} without any dopant. The ability of undoped CeO{sub 2} to remove H{sub 2}S from fuel gases had been determined with a previous DOE/SBIR grant. To make the results obtained under the two grants comparable, the procedures for all phases of this work duplicated that used previously as closely as possible. The sorbents GDC proposed to investigate were: (1) undoped CeO{sub 2}, (2) CeO{sub 2} doped with 5 mole % (5 m/o) magnesium oxide (MgO), and (3) CeO{sub 2} doped with 5 m/o lanthanum oxide (La{sub 2}O{sub 3}). Three additional sorbents: (1) CeO{sub 2} doped with 5 m/o strontium oxide (SrO), (2) CeO{sub 2} doped with 10 m/o SrO, and (2) CeO{sub 2} doped with 10 m/o La{sub 2}O{sub 3} were also investigated. All of these sorbents were prepared using the Marcilly technique.

Not Available

1991-12-15

334

Suspended two-dimensional electron and hole gases  

SciTech Connect

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

Kazazis, D.; Bourhis, E.; Gierak, J.; Gennser, U. [Laboratoire de Photonique et de Nanostructures, CNRS-LPN, Route de Nozay, 91460 Marcoussis (France); Bourgeois, O. [Institut Néel, CNRS-UJF, BP 166, 38042 Grenoble Cedex 9 (France); Antoni, T. [Laboratoire de Photonique et de Nanostructures, CNRS-LPN, Route de Nozay, 91460 Marcoussis, France and Laboratoire Kastler Brossel, Université Pierre et Marie Curie, 4 Place Jussieu, 75005 Paris (France)

2013-12-04

335

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

PubMed

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

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

2014-10-01

336

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

337

Heat Transfer by Free Convection from Horizontal Cylinders in Diatomic Gases  

NASA Technical Reports Server (NTRS)

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.

Hermann, R

1954-01-01

338

Peltier cooling of fermionic quantum gases.  

PubMed

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

Grenier, Ch; Georges, A; Kollath, C

2014-11-14

339

Projection microscopy of photoionization processes in gases  

NASA Astrophysics Data System (ADS)

We demonstrate a method combining laser ionization of molecules with projection technique and allowing observation of photoionization processes in gases with sub-focal spatial micro-resolution. A bunch of molecular ions created by the nonlinear photoionization of the imaging gas near a tip extends in a divergent electrostatic field producing a magnifying image on the detector. It can be used to observe the profile of the sharply-focused intense laser beam in a wide spectral range. In proof of principle experiment the water molecules are ionized in ~40-?m laser focal spot in the vicinity of the silver needle with a curvature radius 0.5 mm and the resultant ions are counted by a position-sensitive scheme. According to our estimations, ~1.5-?m spatial resolution has been reached. Using a sharp tip, the spatial resolution can be improved to the sub-micrometer scale and such approach can be applied for short wavelength beam diagnostics.

Aseyev, S. A.; Minogin, V. G.; Mironov, B. N.

2012-09-01

340

Sir William Ramsay and the noble gases.  

PubMed

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

Davies, Alwyn G

2012-01-01

341

Free electron in compressed inert gases  

SciTech Connect

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

Gordon, E. B. [Russian Academy of Sciences, Institute of Problems of Chemical Physics (Russian Federation)], E-mail: gordon@ficp.ac.ru; Smirnov, B. M. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2008-08-15

342

Free electron in compressed inert gases  

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

343

Voluntary reporting of greenhouse gases 1997  

SciTech Connect

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

NONE

1999-05-01

344

Biomedical imaging with hyperpolarized noble gases.  

PubMed

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. PMID:25360484

Ruppert, Kai

2014-11-01

345

Measuring the Heat Capacity of Greenhouse Gases  

NSDL National Science Digital Library

This quantitative experiment involves lab teams in comparing a sample of room air with one of the greenhouse gases - carbon dioxide, nitrous oxide, or methane - and measuring their heat capacity. The activity requires an infrared heat source, such as a heat lamp, two 2L beverage bottles, #4 one hole rubber stoppers, and a thermometer or temperature probe, volumetric flasks, a graduated cylinder, and tubing. Nitrous oxide can be obtained from a dentist, methane from gas jets in a chemistry lab, and becomes CO² can be generated using vinegar and baking soda. A worksheet guides student calculations of heat capacity of the different samples. The investigation s is supported by the textbook, Climate Change, part of the Global System Science, an interdisciplinary course for high school students that emphasizes how scientists from a wide variety of fields work together to understand significant problems of global impact.

346

Ripples and dots generated by lattice gases  

NASA Astrophysics Data System (ADS)

We show that the emergence of different surface patterns (ripples, dots) can be well understood by a suitable mapping onto the simplest nonequilibrium lattice gases and cellular automata. Using this efficient approach difficult, unanswered questions of surface growth and its scaling can be studied. The mapping onto binary variables facilitates effective simulations and enables one to consider very large system sizes. We have confirmed that the fundamental Kardar-Parisi-Zhang (KPZ) universality class is stable against a competing roughening diffusion, while a strong smoothing diffusion leads to logarithmic growth, a mean-field type behavior in two dimensions. The model can also describe anisotropic surface diffusion processes effectively. By analyzing the time-dependent structure factor we give numerical estimates for the wavelength coarsening behavior.

Ódor, Géza; Liedke, Bartosz; Heinig, Karl-Heinz; Kelling, Jeffrey

2012-02-01

347

Adsorption of Atmospheric Gases on Pu Surfaces  

SciTech Connect

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

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

2012-03-29

348

Concomitant modulated superfluidity in polarized Fermi gases  

SciTech Connect

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.

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

349

Critical UN Conference on Greenhouse Gases Begins  

NSDL National Science Digital Library

Yesterday at the Hague, delegates from over 160 nations began meeting to try to hammer out details of the 1997 Kyoto agreement which mandated that nations reduce their greenhouse gas emissions to pre-1990 levels by the year 2012. This sixth session of the UN's Framework Convention on Climate Change will have to overcome significant obstacles if delegates are to emerge with an agreement within the conference's scheduled two weeks. To begin with, there is disagreement between the European Union and the United States on the use of "clean development mechanisms" (CDMs), which give states a number of ways of reaching the treaty's targets without actually reducing emissions. Among these is a proposal to allow for the trading of emissions credits -- disparagingly viewed by most environmentalists as licenses to pollute -- and the possibility of states with high emissions investing in reforestation projects in developing countries that would serve as "Carbon sinks" to absorb these emissions. Naturally, the US, responsible for 24 percent of the world's greenhouse gases, favors such measures, while the EU -- believing its recent coastal flood to be greenhouse-related -- opposes them in favor of across-the-board reductions and tough sanctions for noncompliance. The US is also concerned that the current draft allows developing nations, including China and India, to pledge to reach emissions limits in the future, but does not hold them to any legal obligation for failure to do so. The United Kingdom has stated that an effective agreement can be reached with or without US support. However, given that the US is the main producer of greenhouse gases, most analysts feel that an agreement without US cooperation is liable to have little long-term consequence.

Charbonneau, David D.

350

Experiments with phase transitions at very high pressure. [compressed solidifed gases, semiconductors, superconductors, and molecular crystals  

NASA Technical Reports Server (NTRS)

Diamond cells were constructed for use to 1 Mbar. A refrigerator for cooling diamond cells was adapted for studies between 15 and 300 K. A cryostat for superconductivity studies between 1.5 to 300 K was constructed. Optical equipment was constructed for fluorescence, transmission, and reflectance studies. X-ray equipment was adapted for use with diamond cells. Experimental techniques were developed for X-ray diffraction studies using synchrotron radiation. AC susceptibility techniques were developed for detecting superconducting transitions. The following materials were studied: compressed solidified gases (Xe, Ar), semiconductors (Ge, Si, GaAs), superconductors (Nb3Ge, Nb3Si, Nb3As, CuCl), molecular crystals (I).

Spain, I. L.

1983-01-01

351

Nonequilibrium mechanism of the optical breakdown of inert gases near a refractory target  

NASA Astrophysics Data System (ADS)

Stationary optical breakdown in inert gases near refractory metals exposed to CW CO2-laser radiation is studied analytically and numerically. Consideration is given to surface temperatures at which the ionization equilibrium in the gas/metal vapor mixture is disrupted and the electron distribution function differs from the Maxwellian one (for tungsten the temperature value is 3.5-4.5 kK). The threshold power density is found to depend on the heat of the metal ion evaporation from the surface.

Gladush, G. G.; Iavokhin, A. N.

1985-10-01

352

Measurements of trace gases above the tropical forests....  

NASA Astrophysics Data System (ADS)

Measurements of trace gases above the tropical forests; A comparison between ozone levels in the forest and the oil palm plantation areas using the BAe -146 aircraft. The atmospheric composition of Sabah region (Borneo) was sampled using the FAAM BAE-146 instrumented aircraft during July 2008 as part of the OP3 (Oxidant particle photochemical processes above a South East Asia tropical rain forest) project. Tropical forests play an important role in the carbon and energy balance of the Earth (which determine global climate) and are themselves vulnerable to climate change. The tropical biosphere is one of the main sources of reactive trace gas emissions into the global atmosphere, and understanding the role of ozone in these areas is of major importance given the rapid changes in land-use in the tropics. This poster presents preliminary ozone concentrations results collected using the FAAM BAE 146 instrumented aircraft over some of Malaysia most extended oil palm plantations; comparing these with the results recorded when flying over forest areas. Oil palm is becoming one of the most widespread tropical crops; in Malaysia 13% of the land area (4.3Mha) is now oil palm plantations (MPOCP, 2008) compared with 1% in 1974 (FAO, 2005). This poster is expected to show very significant ozone concentrations over the two different landscapes. The set-up of the instruments, the specific sampling sites, as well as the land cover areas will be described.

Nicolas-Perea, V.; Monks, P. S.

2009-04-01

353

Solubilities of noble gases in magnetite - Implications for planetary gases in meteorites.  

NASA Technical Reports Server (NTRS)

Solubilities of noble gases in magnetite were determined by growing magnetite in a noble-gas atmosphere between 450 and 700 K. Henry's law is obeyed at pressures up to .01 atm for He, Ne, Ar and up to .00001 atm for Kr, Xe, with the following distribution coefficients at 500 K: He 0.042, Ne 0.016, Ar 3.6, Kr 1.3, Xe 0.88, some 100 to 100,000 times higher than previous determinations on silicate and fluoride melts. Apparent heats of solution are in sharp contrast with earlier determinations on melts which were small and positive, but are comparable to the values for clathrates. Presumably the gases are held in anion vacancies.

Lancet, M. S.; Anders, E.

1973-01-01

354

Trace Gases and Aerosol in the Boundary Layer of the Northern Asia: TROICA Experiments  

NASA Astrophysics Data System (ADS)

The TROICA experiment (Transcontinental Observations Into the Chemistry of the Atmosphere) started in 1995. A mobile railroad laboratory is being used for measurements of atmospheric gases, aerosol, solar radiation and meteorological parameters. The laboratory wagon is directly coupled to the locomotive of a passenger train traveling along electrified railroads of Russia. Eleven expeditions have been conducted to the moment of which nine were performed along the Trans-Siberian railroad from Moscow to Vladivostok (around 9300 km). One expedition was North-South between Murmansk and Kislovodsk, and one was around the mega-city of Moscow. The huge coverage of the continental regions and the repetition of the expeditions provide unique information on processes controlling variability of the key trace gases (O3, NOx, CO, CO2, CH4, some VOCs) and aerosols with high temporal and spatial resolution over different scales from continental to local (hundreds meters). Multiple crossings of settlements allowed determining typical variations of surface gases and aerosol concentrations within cities and their plumes. 222Rn concentration data were used for estimates of CO, CH4 and CO2 nocturnal fluxes from the soil and vegetation. Impacts of different factors, like Western Siberian gas and oil industry, forest fires, transboundary air pollution transport and some other can be evaluated based on the measurement data by comparing them with results of model output and hence can be used for model validation. Emissions of the atmospheric CO and CH4 were studied in several expeditions using isotopes analysis.

Elanksy, N. F.; Aloyan, A. E.; Berezina, E. V.; Elokhov, A. S.; Brenninkmeijer, C. A.; Kopeikin, V. M.; Moeseenko, K. B.; Lavrova, O. V.; Pankratova, N. V.; Safronov, A. N.; Shumsky, R. A.; Skorokhod, A. I.; Tarasova, O. A.; Vivchar, A. V.; Grisenko, A. M.

2007-12-01

355

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

PubMed

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

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

2011-06-01

356

INTRODUCTION Insects exchange respiratory gases through a complex network of  

E-print Network

3409 INTRODUCTION Insects exchange respiratory gases through a complex network of tracheal tubes that open to the environment via spiracular valves. Although some insects are thought to transport gases that produce convection in insect tracheal systems: (i) suction ventilation, in which air movement is driven

Socha, Jake

357

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...

358

Method of converting environmentally pollutant waste gases to methanol  

SciTech Connect

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.

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

1993-08-03

359

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...

360

ANALYSIS OF PROTOCOL GASES - AN ONGOING QUALITY ASSURANCE AUDIT  

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...

361

Continuous cryopump with a method for removal of solidified gases  

DOEpatents

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

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

1989-01-01

362

Health Hazards from Volcanic Gases: A Systematic Literature Review  

Microsoft Academic Search

Millions of people are potentially exposed to volcanic gases worldwide, and exposures may differ from those in anthropogenic air pollution. A systematic literature review found few primary studies relating to health hazards of volcanic gases. SO2 and acid aerosols from eruptions and degassing events were associated with respiratory morbidity and mortality but not childhood asthma prevalence or lung function decrements.

Anna Hansell; Clive Oppenheimer

2004-01-01

363

Apparatus for elimination of nitrogen oxides from combustion waste gases  

Microsoft Academic Search

Nitrogen oxides (NO\\/sub x\\/) are removed from combustion waste gases by injecting gas (NHâ) into the combustion waste gases in the presence of a metallic catalyst to deoxidize the nitrogen oxides to nitrogen and water. A reaction tower has the catalysts moving through so that the dust may be separated from the catalysts and the catalysts may be regenerated continuously.

Y. Hishinuma; H. Akimoto; Z. Tamura; F. Nakajima

1977-01-01

364

Trapping of trace gases in growing ice crystals  

Microsoft Academic Search

An analytical model describing the combined effect of mass accomodation and net adsorption of trace gases on the surfaces of growing ice particles (trapping) is developed. An approximate solution for the release of trapped trace gases from evaporating ice particles is also given. The model fully accounts for the fact that atmospheric ice particles frequently experience substantial subsaturations and supersaturations.

B. Kärcher; M. M. Basko

2004-01-01

365

DUALITY SOLUTIONS FOR PRESSURELESS GASES, MONOTONE SCALAR CONSERVATION LAWS,  

E-print Network

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

d'Orléans, Université

366

Solubility of non-polar gases in electrolyte solutions  

NASA Technical Reports Server (NTRS)

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

Walker, R. L., Jr.

1970-01-01

367

Catalytic device for the catalytic purification of exhaust gases  

Microsoft Academic Search

A catalytic unit for treating gases, particularly exhaust gases of internal combustion engines, containing a monolithic carrier coated with an active catalytic agent, is mounted within a housing by a flexible or elastic, heat-resistant jacket and axially extending slide members interposed between the coated carrier and the housing. The heat-resistant jacket is advantageously prestressed when placed within the housing.

1978-01-01

368

Liquid Level Indicator for Condensed Gases at Low Temperatures  

Microsoft Academic Search

The instrument described here is designed to measure, indicate, record, and control the level of liquefied gases inside a closed vessel. It is especially designed for use at low temperatures with liquefied gases such as nitrogen, oxygen, hydrogen, and helium. It operates on a capacitance principle, and makes use of the difference in dielectric constants of the liquid and vapor.

W. E. Williams Jr.; E. Maxwell

1954-01-01

369

Noble gases and nitrogen in Muong Nong tektites  

Microsoft Academic Search

Three samples of Muong Nong tektites have been studied for N and noble gases. The isotopic composition of noble gases is air-like. The noble gas amounts are much higher than in splash form tektites. As compared to air, He and Ne have been enriched, most likely due to inward diffusion from ambient air, subsequent to glass formation. N contents range

S. V. S. Murty

1997-01-01

370

Temperature Dependence of Viscosities of Common Carrier Gases  

ERIC Educational Resources Information Center

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…

Sommers, Trent S.; Nahir, Tal M.

2005-01-01

371

Emissions of Greenhouse Gases in the United States 1999  

NSDL National Science Digital Library

EIA's annual report on human-caused greenhouse gases in the US shows an annual average increase of 1.1 percent over the past ten years. In 1999, the total emission of greenhouse gases in the US is estimated at 1,833 million metric tons of carbon equivalent, 0.8 percent higher than the estimated level in 1998.

372

Global budgets for non-CO 2 greenhouse gases  

Microsoft Academic Search

The most abundant gases in dry air, N 2 (~ 78.1% by volume) and O 2 (~ 20.95% by volume), represent the equilibrium state of global biogeochemical processes that have operated on time scales of many millions of years. Among the remaining gases, the noble gas argon (~- 0.93 % by volume) is by far most abundant. Because of their

Paul J. Crutzen

1994-01-01

373

Emissions of Greenhouse Gases in the United States 1997  

NSDL National Science Digital Library

The Emissions of Greenhouse Gases in the United States 1997 publication was prepared under the guidance of Mary Hutzler, Director of the Office of Integrated Analysis and Forecasting, Energy Information Administration. This report "presents the latest estimates of emissions for carbon dioxide, methane, nitrous oxide, and other greenhouse gases." The paper states that 82% of U.S. greenhouse gas emissions are caused by coal, petroleum, and natural gas. Gases such as hydroflourocarbons (HFCs), perflourocarbons (PFCs), sulfur hexafluoride, nitrous oxide, methane, and other carbon dioxide gases comprise the other 18% of U.S. emissions. The paper provides an in-depth analysis of Carbon Dioxide Emissions, Methane Emissions, Nitrous Oxide Emissions, Halocarbons and Other Gases, and Land Use Issues, among others.

374

Metamaterials for Cherenkov Radiation Based Particle Detectors  

SciTech Connect

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

Tyukhtin, A. V. [Physical Dep. of St.-Petersburg State University, St.-Petersburg (Russian Federation); Schoessow, P.; Kanareykin, A. [Euclid Techlabs, 1375 Piccard Dr, Rockville, MD 20850 (United States); Antipov, S. [Argonne National Laboratory, 9700 S Cass Ave, Argonne, IL 60439 (United States)

2009-01-22

375

Workshop Report on Managing Solar Radiation  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

376

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

NASA Astrophysics Data System (ADS)

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.

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

1999-09-01

377

Global warming potentials modified for surface radiative forcing for use in surface energy balance models  

Microsoft Academic Search

The radiative impact of greenhouse gases in warming the Earth varies significantly, depending on whether one considers the forcing at the tropopause or at the surface. Compared to the former, the surface forcing for some greenhouse gases is reduced by the interference of water vapour. Hence, we calculate alternative surface global warming potentials (SGWPs) that are derived from the surface

W. F. J. Evans; E. Puckrin

2001-01-01

378

A method for the measurement of the absolute value of the average energy to produce an ion pair in noble gases with X-rays  

Microsoft Academic Search

A method is described that allows the measurement of the absolute value of the average energy to produce an ion pair in noble gases for soft X-rays and its energy dependence. It uses a specially designed gas proportional scintillation counter working under electric fields below the ionization threshold. The spectrum of the radiation absorbed, and thus the number of photons

Filipa I. G. M. Borges; C. A. N. Conde

1992-01-01

379

Importance of Corneal Thickness  

MedlinePLUS

The Importance of Corneal Thickness email Send this article to a friend by filling out the fields below: Your name: Your friend's name: ... intraocular eye pressure and glaucoma development. Why is Corneal Thickness Important? Corneal thickness is important because it ...

380

Interactions of Hydrazine and Blowby Gases  

NASA Technical Reports Server (NTRS)

The interactions between hydrazine and blowby gases from pyrovalves was explored in this research project. Investigating the decomposition chemistry of hydrazine through detailed chemical kinetic modeling is a project started last summer while participating in the Summer Faculty Fellowship program. During the 1999-2000 academic year, the chemical kinetic mechanism for hydrazine decomposition developed while a SFF at NASA's White Sands Test Facility was further revised and validated against the limited experimental data in the literature. This mechanism was then used in assessing the effects of blowby gas species on hydrazine decomposition. The combustion products introduced into the fuel line by pyrovalve actuation consist primarily of hydrogen gas. Hydrogen is also a product of the decomposition of hydrazine. Additional gaseous chemical species are introduced into the fuel, as well as metals and metal salts that deposit onto the walls of the fuel line. The deposition process is undoubtedly very rapid, and exothermic. Therefore, the major focus of this summer's work was examining the effects of hydrogen presence on hydrazine decomposition, with some representative calculations including the remaining gaseous species found to exist in blowby gases. Since hydrogen is a product of hydrazine decomposition, all reactions necessary to evaluate its effect on hydrazine decomposition chemistry were in the original mechanism developed. However, the mechanism needed to be considerably expanded to include the reactions of the other gaseous blowby species with hydrazine, all the intermediate species formed in its decomposition, and each other. The expanded mechanism consists of 70 species interacting via a network of 452 reactions. Calculations with molecular hydrogen introduced into hydrazine gas in an inert bath gas indicate that H2 presence as an initial reactant in substantial amounts can dramatically impact the decomposition process for hydrazine. The other gaseous blowby species (CO, CO2, H2O, CH4, O2, and N2) were found to have little effect compared to the inclusion of hydrogen itself as an initial reagent. This result is undoubtedly due, in part, to the fact that the blowby gas used in these calculations consisted of 94.6% H2. A more rigorous examination of the behavior of the full detailed mechanism under a variety of conditions was not performed.

Meagher, Nancy E.

2003-01-01

381

Cloud-radiation interactions - Effects of cirrus optical thickness feedbacks  

NASA Technical Reports Server (NTRS)

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

Somerville, Richard C. J.; Iacobellis, Sam

1987-01-01

382

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

Code of Federal Regulations, 2010 CFR

...Requirements for Class 2 (Gases) Materials § 174.204 Tank car delivery of gases, including cryogenic liquids...tank car containing Class 2 (gases) material may not be...Division 2.1 (flammable gas) material that is a...

2010-10-01

383

49 CFR 173.304 - Filling of cylinders with liquefied compressed gases.  

Code of Federal Regulations, 2010 CFR

...liquefied compressed gases. (a) General...liquefied compressed gas (except gas...mixture of compressed gas must be shipped in...Refrigerant and dispersant gases. Nontoxic and nonflammable...flammable compressed gas or gases must be shipped...

2010-10-01

384

A Group Increment Scheme for Infrared Absorption Intensities of Greenhouse Gases  

NASA Technical Reports Server (NTRS)

A molecule's absorption in the atmospheric infrared (IR) window (IRW) is an indicator of its efficiency as a greenhouse gas. A model for estimating the absorption of a fluorinated molecule within the IRW was developed to assess its radiative impact. This model will be useful in comparing different hydrofluorocarbons and hydrofluoroethers contribution to global warming. The absorption of radiation by greenhouse gases, in particular hydrofluoroethers and hydrofluorocarbons, was investigated using ab initio quantum mechanical methods. Least squares regression techniques were used to create a model based on this data. The placement and number of fluorines in the molecule were found to affect the absorption in the IR window and were incorporated into the model. Several group increment models are discussed. An additive model based on one-carbon groups is found to work satisfactorily in predicting the ab initio calculated vibrational intensities.

Kokkila, Sara I.; Bera, Partha P.; Francisco, Joseph S.; Lee, Timothy J.

2012-01-01

385

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

SciTech Connect

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.

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

386

Geostationary atmospheric infrared sounder: trace gases sensitivity  

NASA Astrophysics Data System (ADS)

The NASA sponsored Advanced Geosynchronous Studies (AGS) program is to conduct intensive studies to demonstrate the use of advanced new technologies and instruments on geosynchronous satellites to improve our current capabilities of monitoring the global weather, climate, and chemistry. The Geostationary Atmospheric Sounder (GAS), to be developed under AGS, is intended to demonstrate a new space-based infrared imaging interferometer that is well suited for achieving the high temporal and spatial global coverage of cloud motion, water vapor transport, thermal and moisture vertical profiles, land and ocean surface temperature, and trace gas concentrations. The AGS technology demonstrations will show the capabilities of passive infrared observations from future NOAA geostationary operational sounders. The focus of this presentation is to provide quantitative assessments of a few design configurations for the trace gases sounding feasibility from geostationary orbit. Trade-off studies of spectral, temporal, and spatial resolution are to be emphasized. Preliminary conclusions for the design of an operational geo sounder for chemistry applications will be made.

Huang, Allen H.; Li, Jun; Thom, Jonathan; Huang, Bormin; Smith, William L.; Woods-Vedeler, Jessica; Parsons, Vicki S.

1999-10-01

387

Neutralization of thoron progeny in gases.  

PubMed

This paper reports charge neutralization phenomena of 212Pb 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, we have found that the diffusion coefficients of 212Pb in O2, N2, NH3/O2, NH3/N2, and C6H12/N2 (IPs between 15.58 and 9.8 eV) ranged between 0.015 and 0.030 cm2 s-1. In the case of C6H12/O2, NO2/O2, NO/O2, and dimethylamine/O2 (ionization potential between 9.8 and 8.23 eV), the diffusion coefficients have increased to between 0.046 and 0.69 cm2 s-1. These results are consistent with previous results of 218Po, indicating that charged progeny are neutralized by electron transfer from a gas molecule with a lower ionization potential than lead oxide. We estimate the ionization potential of lead oxide to range between 9.8 and 10.2 eV. 212Pb was also neutralized by an electron scavenging mechanism in NO2/nitrogen. PMID:8026969

Cheng, Y S; Yu, C C; Tung, C J; Hopke, P K

1994-08-01

388

Transport of Greenhouse Gases in Trees  

NASA Astrophysics Data System (ADS)

Emissions of greenhouse gases methane (CH4) and nitrous oxide (N2O) have been measured in cultivated and natural regions, quantifying overall emissions for croplands, wetlands, and forests. However, segregation between soil and plant emissions is less clear, and the dynamics behind each respective emission type differs. Better defined plant transport mechanisms will yield more accurate determination of greenhouse gas flux, contributing to a comprehensive theory quantifying greenhouse gas emissions globally. While the mechanisms of CH4 and N2O emissions from rice have not been fully identified, for trees these mechanisms are virtually unknown. CH4 and N2O emissions from several species of tree (Alnus rubra, Populus trichocarpa, Thuja plicata, Fraxinus latifolia) native to the Pacific Northwest have been measured. To identify mechanisms of gas transport, correlation of emissions and stomatal conductance, transpiration, and photosynthesis has been tested. A synthesis between plant physiological data and emissions is sought to elucidate the role plant physiology plays in the production and transport of CH4 and N2O. This research was supported by the Office of Science (BER), U. S. Department of Energy, Grant No. DE-FG02-08ER64515.

Kutschera, E.; Khalil, A. K.; Shearer, M.; Rosenstiel, T.

2009-12-01

389

Universal nonequilibrium properties of dissipative Rydberg gases.  

PubMed

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 Z_{2} 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

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

2014-11-21

390

Universal Nonequilibrium Properties of Dissipative Rydberg Gases  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

391

Measuring non-condensable gases in steam  

SciTech Connect

In surgery, medical devices that are used should be sterilized. To obtain surface steam sterilization conditions, not only in the sterilizer chamber itself but also in the loads to be sterilized, the amount of non-condensable gases (NCGs), for instance air, should be very low. Even rather small fractions of NCGs (below 1 %) seriously hamper steam penetration in porous materials or devices with hollow channels (e.g., endoscopes). A recently developed instrument which might detect the presence of residual NCGs in a reliable and reproducible way is the 3M{sup TM} Electronic Test System (ETS). In this paper, a physical model is presented that describes the behavior of this instrument. This model has been validated by experiments in which known fractions of NCGs were introduced in a sterilizer chamber in which an ETS was placed. Despite several approximations made in the model, a good agreement is found between the model predictions and the experimental results. The basic principle of the ETS, measuring the heat transfer by condensation on a cooled surface, permits a very sensitive detection of NCGs in harsh environments like water vapor at high temperatures and pressures. Our model may serve to develop adapted and optimized versions of this instrument for use outside the field of sterilization, e.g., in heat exchangers based on steam condensation.

Doornmalen, J. P. C. M. van; Kopinga, K., E-mail: k.kopinga@tue.nl [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2013-11-15

392

Quantum Degenerate Gases of Atomic Strontium  

NASA Astrophysics Data System (ADS)

This talk will describe the production and properties of a Bose-Einstein condensate of ^84Sr and a quantum degenerate mixture of ^87Sr (fermion) and ^88Sr (boson). ^88Sr has a small negative scattering length leading to a maximum condensate size for our trapping conditions of about 10^4 atoms. ^87Sr is used to sympathetically cool ^88Sr, but it is also of interest for study of quantum degenerate Fermi gases because it has a large nuclear spin (I=9/2). Alkaline-earth metal atoms and atoms with similar electronic structure are of interest for quantum computing proposals, cold collision studies, and investigation of quantum fluids. There are a wealth of isotopes that allow mass-tuning of interactions and creation of various quantum mixtures. The two-valence electrons lead to a singlet ground state and narrow intercombination transitions to metastable triplet states, offering the promise of low-loss optical Feshbach resonances for manipulating scattering lengths. Fermions often have large nuclear spin, which is decoupled from electronic degrees of freedom and leads to a large degree of symmetry and degeneracy in the interaction Hamiltonian. Work done in collaboration with Y.N. Martinez de Escobar, P.G. Mickelson, M. Yan, B.J. DeSalvo, and S.B. Nagel, Rice University.

Killian, T. C.

2010-03-01

393

Application of Detached Eddy Simulation to neighbourhood scale gases atmospheric dispersion modelling.  

PubMed

This paper addresses the current important problem of modelling the dispersion of toxic gases released in the urban terrains (i.e. neighbourhood scale) by the Detached Eddy Simulation (DES). This approach is a resolution that lays between the Reynolds Averaged Navier-Stokes and Large Eddy Simulation models and focuses especially on establishing a better balance between efficiency and accuracy. Herein are presented the theoretical approach of a new model, which is based on the DES and the Spalart-Almaras turbulent closure and a number of validation tests like the flow and the dispersion over and around a single building and an array of buildings. Overall, employed validation metrics were within the acceptable limits and the model demonstrated an acceptable agreement with the experimental datasets which confirms the use of this approach for the modelling and dispersion of gases in complex terrains like a city. PMID:23995562

Kakosimos, K E; Assael, M J

2013-10-15

394

Methane activation using noble gases in a dielectric barrier discharge reactor  

SciTech Connect

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.

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

395

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

SciTech Connect

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.

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

396

Perfluoroalkyl Amines: A New Class of Long-Lived Greenhouse Gases?  

NASA Astrophysics Data System (ADS)

Polyfluorinated compounds have the potential to act as potent greenhouse gases, due to absorption of the carbon-fluorine bond in the atmospheric window. Perfluoroalkyl amines are a class of thermally and chemically stable compounds marketed for use in numerous applications, including electronic testing and heat transfer. To assess the potential for climate impact, the radiative efficiency and atmospheric lifetime of perfluorotributyl amine (PFBAm) were determined. PFBAm was shown to have a radiative efficiency of 0.86 W m-2 ppb-1, which is higher than any compound yet detected in the atmosphere. The lifetime of this compound is likely limited by photolysis in the mesosphere, on the timescale of 800 years. The potential for perfluoroalkyl amines to behave as greenhouse gases is only realized if they are present in the atmosphere. The perfluorotripropyl and perfluorotrihexyl amine congeners are listed as high-production chemicals, with production in the range of hundreds of tonnes between 1986 and 2002 (1). An air sampling, extraction and analysis method employing thermal desorption, cryofocusing and GC-MS with negative chemical ionization has been developed to detect perfluoroalkyl amines in the atmosphere. Results and implications of the air sampling study will be discussed. (1)Howard, P. H.; Meylan, W. "EPA Great Lakes Study for Identification of PBTs to Develop Analytical Methods: Selection of Additional PBTs - Interim Report," EPA Contract No. EP-W-04-019, 2007.

Young, C. J.; Mabury, S. A.

2008-12-01

397

Implementation of non-condensable gases condensation suppression model into the WCOBRA/TRAC-TF2 LOCA safety evaluation code  

SciTech Connect

The non-condensable gases condensation suppression model is important for a realistic LOCA safety analysis code. A condensation suppression model for direct contact condensation was previously developed by Westinghouse using first principles. The model is believed to be an accurate description of the direct contact condensation process in the presence of non-condensable gases. The Westinghouse condensation suppression model is further revised by applying a more physical model. The revised condensation suppression model is thus implemented into the WCOBRA/TRAC-TF2 LOCA safety evaluation code for both 3-D module (COBRA-TF) and 1-D module (TRAC-PF1). Parametric study using the revised Westinghouse condensation suppression model is conducted. Additionally, the performance of non-condensable gases condensation suppression model is examined in the ACHILLES (ISP-25) separate effects test and LOFT L2-5 (ISP-13) integral effects test. (authors)

Liao, J.; Cao, L.; Ohkawa, K.; Frepoli, C. [LOCA Integrated Services I, Westinghouse Electric Company, 1000 Westinghouse Drive, Cranberry Township, PA 16066 (United States)

2012-07-01

398

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

399

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

Microsoft Academic Search

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

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

2004-01-01

400

Extreme sensitivity of graphene photoconductivity to environmental gases  

PubMed Central

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

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

2012-01-01

401

The stability of compressible mixing layers in binary gases  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

402

Cryogenic method for measuring nuclides and fission gases  

DOEpatents

A cryogenic method is provided for determining airborne gases and particulates from which gamma rays are emitted. A special dewar counting vessel is filled with the contents of the sampling flask which is immersed in liquid nitrogen. A vertically placed sodium-iodide or germanium-lithium gamma-ray detector is used. The device and method are of particular use in measuring and identifying the radioactive noble gases including emissions from coal-fired power plants, as well as fission gases released or escaping from nuclear power plants.

Perdue, P.T.; Haywood, F.F.

1980-05-02

403

Nitrogen and light noble gases in Parsa enstatite chondrite  

NASA Technical Reports Server (NTRS)

Solar gases have been recently reported in Parsa, an EH3 chondrite. In an effort to check whether solar gases are uniformly distributed throughout Parsa or they are located in specific phases, we analyzed two additional samples of bulk Parsa and one aubritic nodule for N and noble gases. Nitrogen studies are intended for the understanding of the nitrogen components distribution in E-chondrites. The N-systematics of the nodule are entirely different from the bulk samples. The higher N contents in this nodule, as well as its complex delta(sup 15)N structure, as compared to the normal aubrites, is suggestive that the nodule is not a genuine aubrite.

Murty, S. V. S.

1993-01-01

404

Study of laser induced plasma grating dynamics in gases  

NASA Astrophysics Data System (ADS)

The relaxation of a plasma grating resulting from the interference of two crossing laser filaments in molecular and atomic gases is studied experimentally. Dissipation of the grating fringes is dominated by ambipolar diffusion in atomic gases and by a combination of ambipolar diffusion and collision-assisted free electron recombination in molecular gases. A theoretical model of the grating evolution is developed and compared to experimental results. Good agreement with simulations allows extracting plasma properties such as electron density, diffusion and recombination coefficients in Ne, Ar, Kr, Xe, N2, O2, CO2 and air at atmospheric pressure.

Jarnac, A.; Durand, M.; Liu, Y.; Prade, B.; Houard, A.; Tikhonchuk, V.; Mysyrowicz, A.

2014-02-01

405

Defects in GaSe grown by Bridgman method.  

PubMed

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

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

406

Topics in the Mathematical Physics of Cold Bose Gases  

E-print Network

In these notes of six lectures on selected topics in the theory of cold, dilute Bose gases, presented at the 5th Warsaw School of Statistical Physics in June 2013, the following topics are discussed: 1) The concept of BEC, 2) the ground state energy of a dilute Bose gas with short range interactions, 3) Gross-Pitaevskii theory and BEC in trapped gases, 4) Bose gases in rotating traps and quantized vortices, and 5) strongly correlated phases in the lowest Landau level generated by rapid rotation.

Jakob Yngvason

2014-02-04

407

EDITORIAL: The 20th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases The 20th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases  

NASA Astrophysics Data System (ADS)

This special issue consists of papers that are associated with invited lectures, workshop papers and hot topic papers presented at the 20th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases (ESCAMPIG XX). This conference was organized in Novi Sad (Serbia) from 13 to 17 July 2010 by the Institute of Physics of the University of Belgrade. It is important to note that this is not a conference 'proceedings'. Following the initial selection process by the International Scientific Committee, all papers were submitted to the journal by the authors and have been fully peer reviewed to the standard required for publication in Plasma Sources Science and Technology (PSST). The papers are based on presentations given at the conference but are intended to be specialized technical papers covering all or part of the topic presented by the author during the meeting. The ESCAMPIG conference is a regular biennial Europhysics Conference of the European Physical Society focusing on collisional and radiative aspects of atomic and molecular physics in partially ionized gases as well as on plasma-surface interaction. The conference focuses on low-temperature plasma sciences in general and includes the following topics: Atomic and molecular processes in plasmas Transport phenomena, particle velocity distribution function Physical basis of plasma chemistry Plasma surface interaction (boundary layers, sheath, surface processes) Plasma diagnostics Plasma and discharges theory and simulation Self-organization in plasmas, dusty plasmas Upper atmospheric plasmas and space plasmas Low-pressure plasma sources High-pressure plasma sources Plasmas and gas flows Laser-produced plasmas During ESCAMPIG XX special sessions were dedicated to workshops on: Atomic and molecular collision data for plasma modeling, organized by Professors Z Lj Petrovic and N Mason Plasmas in medicine, organized by Dr N Puac and Professor G Fridman. The conference topics were represented in the program by 16 invited lectures, 7 selected hot topics, and 191 poster presentations. The largest number of contributed papers was submitted in Topic 5: Plasma diagnostics (37). The workshop topics were addressed by 10 invited lectures, 5 oral presentations and 7 posters. A post-conference workshop with 5 invited lectures was organized, dealing with the data needs for modeling of plasma sources of light. ESCAMPIG XX was attended by 185 scientists from 31 countries. Of the participants, 30% were PhD students (55). The list includes scientists from the USA, Japan, Australia, Mexico and other non-European countries, which indicates the truly international status of the conference. We would like to thank the authors for their efforts in preparing stimulating lectures and interesting articles for the readers of PSST, and the scientific community dealing with ionized gases, plasma sources and atomic, molecular and chemical physics of low-temperature plasmas for continued interest in the field of ESCAMPIG. We would like to thank the organizers of all previous ESCAMPIG conferences for setting the standards for organization and, in particular, the organizers of ESCAMPIG XVIII and XIX for their direct help and insight. Finally the International Scientific Committee and its chairman in particular have worked hard to select the best possible program and to keep us in line with almost 40 years of tradition and standards of the conference. Most importantly this has been the 20th conference. The quality of new papers shows maturity and new vistas in the field that has produced so much fundamental understanding of complex, non-equilibrium, even nonlinear plasmas. At the same time the field has led to some of the key technologies of modern civilization and has shown that responsible science that pays attention to its societal benefits should have no fear for its future. All critical issues studied today were presented at the meeting and only a small part is represented here. For example, discharges in liquids or above liquids were covered by several lectures represented by two pa

Petrovi?, Zoran Lj; Mari?, Dragana; Malovi?, Gordana

2011-03-01

408

Radiation enteritis  

MedlinePLUS

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

409

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

PubMed

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

Herrmann, Th; Müller, R

2012-11-01

410

Observations of atmospheric trace gases by MAX-DOAS in the coastal boundary layer over Jiaozhou Bay  

NASA Astrophysics Data System (ADS)

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.

Li, Xianxin; Wang, Zhangjun; Meng, Xiangqian; Zhou, Haijin; Du, Libin; Qu, Junle; Chen, Chao; An, Quan; Wu, Chengxuan; Wang, Xiufen

2014-11-01

411

Quantum cascade laser based sensor for in situ and real time atmospheric trace gases (CO and N2O) measurements  

NASA Astrophysics Data System (ADS)

In addition to the primary greenhouse gases carbon dioxide (CO2) and methane (CH4), several other atmospheric trace gases are radiatively active, and thereby can also contribute to a greenhouse warming of the lower atmosphere directly or indirectly. Nitrous oxide (N2O) is a greenhouse gas with a global warming potential about 200-300 times that of CO2. Carbon monoxide (CO) is not considered a direct greenhouse gas, mostly because it does not absorb terrestrial thermal IR energy strongly enough. However, CO plays an important role in the oxidative chemistry of Earth's atmosphere, since it is a key trace gas for controlling the budget and distribution of the hydroxyl (OH) radical, which exerts a controlling influence on the gas phase chemistry of many atmospheric species [1]. Therefore, there is a critical need to identify sources and sinks of N2O and CO in order to better understand their impact on global climate change [2]. We present a fast, compact, and precise sensor based-on a novel thermoelectrically (TE) cooled quantum cascade laser (QCL) operating at near-room temperature in CW (continuous-wave) mode for simultaneous detection of atmospheric N2O and CO. The technique is based on atmospheric absorption of these trace species in the mid-infrared region near 4.56 µm, using a single QC laser source and two TE-cooled infrared detectors. Wavelength modulation spectroscopy with second harmonic detection technique in conjunction with a compact multi-pass absorption cell has been employed to demonstrate highly sensitive and precise measurements. CO and N2O at ambient concentration levels are detected simultaneously with a high temporal response (< 1s). Preliminary results (Laboratory investigation and field application) of the sensor's performance will be presented. This completely TE-cooled system shows the capability of long-term, unattended and continuous operation at room temperature without complicated cryogenic cooling [3]. [1] J. A. Logan, M. J. Prather, S. C. Wofsy, and M. B. Mcelroy; J. Geophys. Res. 86, 7210-7254 (1981). [2] S. A. Montzka, E. J. Dlugokencky, and J. H. Butler; Nature 476, 43-50 (2011). [3] J.S. Li, U. Parchatka, R. Königstedt, and H. Fischer; Opt. Express 20,7590-7601 (2012).

Li, Jingsong; Parchatka, Uwe; Fischer, Horst

2013-04-01

412

Thermal maps of gases in heterogeneous reactions  

NASA Astrophysics Data System (ADS)

More than 85 per cent of all chemical industry products are made using catalysts, the overwhelming majority of which are heterogeneous catalysts that function at the gas-solid interface. Consequently, much effort is invested in optimizing the design of catalytic reactors, usually by modelling the coupling between heat transfer, fluid dynamics and surface reaction kinetics. The complexity involved requires a calibration of model approximations against experimental observations, with temperature maps being particularly valuable because temperature control is often essential for optimal operation and because temperature gradients contain information about the energetics of a reaction. However, it is challenging to probe the behaviour of a gas inside a reactor without disturbing its flow, particularly when trying also to map the physical parameters and gradients that dictate heat and mass flow and catalytic efficiency. Although optical techniques and sensors have been used for that purpose, the former perform poorly in opaque media and the latter perturb the flow. NMR thermometry can measure temperature non-invasively, but traditional approaches applied to gases produce signals that depend only weakly on temperature are rapidly attenuated by diffusion or require contrast agents that may interfere with reactions. Here we present a new NMR thermometry technique that circumvents these problems by exploiting the inverse relationship between NMR linewidths and temperature caused by motional averaging in a weak magnetic field gradient. We demonstrate the concept by non-invasively mapping gas temperatures during the hydrogenation of propylene in reactors packed with metal nanoparticles and metal-organic framework catalysts, with measurement errors of less than four per cent of the absolute temperature. These results establish our technique as a non-invasive tool for locating hot and cold spots in catalyst-packed gas-solid reactors, with unprecedented capabilities for testing the approximations used in reactor modelling.

Jarenwattananon, Nanette N.; Glöggler, Stefan; Otto, Trenton; Melkonian, Arek; Morris, William; Burt, Scott R.; Yaghi, Omar M.; Bouchard, Louis-S.

2013-10-01

413

49 CFR 173.307 - Exceptions for compressed gases.  

...compressed gases. (a) The following materials are not subject to the requirements of this subchapter: (1) Carbonated beverages. (2) Tires when inflated to pressures not greater than their rated inflation pressures. For...

2014-10-01

414

49 CFR 173.307 - Exceptions for compressed gases.  

Code of Federal Regulations, 2013 CFR

...compressed gases. (a) The following materials are not subject to the requirements of this subchapter: (1) Carbonated beverages. (2) Tires when inflated to pressures not greater than their rated inflation pressures. For...

2013-10-01

415

49 CFR 173.307 - Exceptions for compressed gases.  

Code of Federal Regulations, 2011 CFR

...compressed gases. (a) The following materials are not subject to the requirements of this subchapter: (1) Carbonated beverages. (2) Tires when inflated to pressures not greater than their rated inflation pressures. For...

2011-10-01

416

49 CFR 173.307 - Exceptions for compressed gases.  

Code of Federal Regulations, 2012 CFR

...compressed gases. (a) The following materials are not subject to the requirements of this subchapter: (1) Carbonated beverages. (2) Tires when inflated to pressures not greater than their rated inflation pressures. For...

2012-10-01

417

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...

418

40 CFR 600.108-08 - Analytical gases.  

...CONTINUED) ENERGY POLICY FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF MOTOR VEHICLES Fuel Economy and Carbon-Related Exhaust Emission... The analytical gases for all fuel economy testing must meet the criteria...

2014-07-01

419

Radio-frequency spectroscopy of ultracold atomic Fermi gases  

E-print Network

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 ...

Schirotzek, Andre

2010-01-01

420

Studying coherence in ultra-cold atomic gases  

E-print Network

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 ...

Miller, Daniel E. (Daniel Edward)

2007-01-01

421

Estimating the Solubility of Gases in Battery Electrolytes  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

422

Method of producing pyrolysis gases from carbon-containing materials  

DOEpatents

A gasification process of improved efficiency is disclosed. A dual bed reactor system is used in which carbon-containing feedstock materials are first treated in a gasification reactor to form pyrolysis gases. The pyrolysis gases are then directed into a catalytic reactor for the destruction of residual tars/oils in the gases. Temperatures are maintained within the catalytic reactor at a level sufficient to crack the tars/oils in the gases, while avoiding thermal breakdown of the catalysts. In order to minimize problems associated with the deposition of carbon-containing materials on the catalysts during cracking, a gaseous oxidizing agent preferably consisting of air, oxygen, steam, and/or mixtures thereof is introduced into the catalytic reactor at a high flow rate in a direction perpendicular to the longitudinal axis of the reactor. This oxidizes any carbon deposits on the catalysts, which would normally cause catalyst deactivation.

Mudge, Lyle K. (Richland, WA); Brown, Michael D. (West Richland, WA); Wilcox, Wayne A. (Kennewick, WA); Baker, Eddie G. (Richland, WA)

1989-01-01

423

Method for monitoring stack gases for uranium activity  

DOEpatents

A method for monitoring the stack gases of a purge cascade of gaseous diffusion plant for uranium activity. A sample stream is taken from the stack gases and contacted with a volume of moisture-laden air for converting trace levels of uranium hexafluoride, if any, in the stack gases into particulate uranyl fluoride. A continuous strip of filter paper from a supply roll is passed through this sampling stream to intercept and gather any uranyl fluoride in the sampling stream. This filter paper is then passed by an alpha scintillation counting device where any radioactivity on the filter paper is sensed so as to provide a continuous monitoring of the gas stream for activity indicative of the uranium content in the stack gases. 1 fig.

Beverly, C.R.; Ernstberger, E.G.

1985-07-03

424

Viscosities of natural gases at high pressures and high temperatures  

E-print Network

Estimation of viscosities of naturally occurring petroleum gases provides the information needed to accurately work out reservoir-engineering problems. Existing models for viscosity prediction are limited by data, especially at high pressures...

Viswanathan, Anup

2007-09-17

425

Spin transport in polaronic and superfluid Fermi gases  

E-print Network

We present measurements of spin transport in ultracold gases of fermionic 6Li in a mixture of two spin states at a Feshbach resonance. In particular, we study the spin-dipole mode, where the two spin components are displaced ...

Sommer, Ariel Tjodolv

426

Trace Gases, CO2, Climate, and the Greenhouse Effect.  

ERIC Educational Resources Information Center

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)

Aubrecht, Gordon J., II

1988-01-01

427

Method for monitoring stack gases for uranium activity  

DOEpatents

A method for monitoring the stack gases of a purge cascade of a gaseous diffusion plant for uranium activity. A sample stream is taken from the stack gases and contacted with a volume of moisture-laden air for converting trace levels of uranium hexafluoride, if any, in the stack gases into particulate uranyl fluoride. A continuous strip of filter paper from a supply roll is passed through this sampling stream to intercept and gather any uranyl fluoride in the sampling stream. This filter paper is then passed by an alpha scintillation counting device where any radioactivity on the filter paper is sensed so as to provide a continuous monitoring of the gas stream for activity indicative of the uranium content in the stack gases.

Beverly, Claude R. (Paducah, KY); Ernstberger, Harold G. (Paducah, KY)

1988-01-01

428

Process for the removal of acid forming gases from exhaust gases  

DOEpatents

Exhaust gases are treated to remove NO or NO[sub x] and SO[sub 2] by contacting the gases with an aqueous emulsion or suspension of yellow phosphorus preferably in a wet scrubber. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50 C is attractive. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO[sub x] and SO[sub 2], alkalis that are used for flue gas desulfurization are preferred. With this process, 100% of the by-products created are usable, and close to 100% of the NO or NO[sub x] and SO[sub 2] can be removed in an economic fashion. 9 figs.

Chang, S.G.; Liu, D.K.

1992-11-17

429

Relative Contribution of Greenhouse Gases and Ozone Change to Temperature Trends in the Stratosphere: A Chemistry/Climate Model Study  

NASA Technical Reports Server (NTRS)

Long-term changes in greenhouse gases, primarily carbon dioxide, are expected to lead to a warming of the troposphere and a cooling of the stratosphere. We examine the cooling of the stratosphere and compare the contributions greenhouse gases and ozone change for the decades between 1980 and 2000. We use 150 years of simulation done with our coupled chemistry/climate model (GEOS 4 GCM with GSFC CTM chemistry) to calculate temperatures and constituents fiom,1950 through 2100. The contributions of greenhouse gases and ozone to temperature change are separated by a time-series analysis using a linear trend term throughout the period to represent the effects of greenhouse gases and an equivalent effective stratospheric chlorine (EESC) term to represent the effects of ozone change. The temperature changes over the 150 years of the simulation are dominated by the changes in greenhouse gases. Over the relatively short period (approx. 20 years) of ozone decline between 1980 and 2000 changes in ozone are competitive with changes in greenhouse gases. The changes in temperature induced by the ozone change are comparable to, but smaller than, those of greenhouse gases in the upper stratosphere (1-3 hPa) at mid latitudes. The ozone term dominates the temperature change near both poles with a negative temperature change below about 3-5 hPa and a positive change above. At mid latitudes in the upper stratosphere and mesosphere (above about 1 hPa) and in the middle stratosphere (3 to 70 ma), the greenhouse has term dominates. From about 70 hPa down to the tropopause at mid latitudes, cooling due to ozone changes is the largest influence on temperature. Over the 150 years of the simulation, the change in greenhouse gases is the most important contributor to temperature change. Ozone caused a perturbation that is expected to reverse over the coming decades. We show a model simulation of the expected temperature change over the next two decades (2006-2026). The simulation shows a crossover between lower atmospheric heating and upper atmospheric cooling that is located at about 90 hPa in the tropics and 30-40 hPa in the polar regions. This results from the combination of continuing increases in greehouse gases and recovery from ozone depletion.

Stolarski, Richard S.; Douglass, A. R.; Newman, P. A.; Pawson, S.; Schoeberl, M. R.

2006-01-01

430

Cell Model of In-cloud Scavenging of Highly Soluble Gases  

NASA Astrophysics Data System (ADS)

Transport of soluble gases in clouds is an integral part of the atmospheric transport of gases and is important for understanding the global distribution pattern of soluble trace gases. In the present study we investigated mass transfer during absorption of highly soluble gases such as hydrogen peroxide H2O2 and nitric acid HNO3 by stagnant cloud droplets in the presence of inert admixtures. Diffusion interactions between droplets, caused by the overlap of depleted of soluble gas regions around the neighboring droplets, are taken into account in the approximation of a cellular model of a gas-droplet suspension whereby a suspension is viewed as a periodic structure consisting of the identical spherical cells with periodic boundary conditions at the cell boundary. Using this model we determined temporal and spatial dependencies of the concentration of the soluble trace gas in a gaseous phase and in a droplet and calculated the dependence of the scavenging coefficient on time. It is shown that scavenging of highly soluble gases by cloud droplets leads to essential decrease of soluble trace gas concentration in the interstitial air. We found that scavenging coefficient for gas absorption by cloud droplets remains constant and sharply decreases only at the final stage of absorption. This assertion implies the exponential time decay of the average concentration of the soluble trace gas in the gaseous phase and can be used for the parameterization of gas scavenging by cloud droplets in the atmospheric transport modeling. In the calculations we employed gamma size distribution of cloud droplets. It was shown that despite of the comparable values of Henry's law constants for the hydrogen peroxide and the nitric acid, the nitric acid is scavenged more effectively by cloud than the hydrogen peroxide due to a major affect of the dissociation reaction on nitric acid scavenging. We obtained also the analytical expressions for the "equilibrium values" of concentration of the active gas in a gaseous phase and for the total concentration in the liquid phase for the case of the hydrogen peroxide and nitric acid absorption by cloud droplets. The developed cell model of in-cloud scavenging of highly soluble gases or parameterizations based on its results can be easily integrated into online coupled meteorology-chemistry or climate-chemistry models, where the cloud processes and chemical transformation of atmospheric pollutants are considered together with two-way interactions.

Baklanov, A.; Elperin, T.; Fominykh, A.; Krasovitov, B.

2012-04-01

431

Biological production of ethanol from waste gases with Clostridium ljungdahlii  

DOEpatents

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.

Gaddy, James L. (Fayetteville, AR)

2000-01-01

432

Inductively coupled plasmas in low global-warming-potential gases  

Microsoft Academic Search

Many high-density discharges used in microelectronics fabrication use fluorocarbon gases with coincidentally high global-warming potentials (GWPs). We have determined the identities, fluxes, and energy distributions of ions produced in high-density discharges generated in two low GWP gases, CF3I and CF3CH2F (HFC-134a), which have attracted interest for plasma processing applications. Measurements were made using a combined ion energy analyser-mass spectrometer that

A. N. Goyette; Yicheng Wang; J. K. Olthoff

2000-01-01

433

Apparatus for cleaning blast-furnace exhaust gases  

Microsoft Academic Search

An apparatus for cleaning the exhaust gas of a high-pressure blast furnace comprises a coarse-particle separator, a prewasher and a differential-pressure annular gap washer traversed in succession by the gases. The exhaust gases can be passed through a main duct provided with an expansion turbine or through a bypass duct around the expansion turbine. The expansion turbine unit controls the

K. R. Hegemann; G. Finger; A. Brinkmann; H. Weissert

1977-01-01

434

Resource Article: Experiments with Vortices in Superfluid Atomic Gases  

Microsoft Academic Search

Observations of quantized vortices in dilute-gas Bose-Einstein condensates were first reported in 1999. Over the next 10 years, more than 70 papers describing experiments involving vortices in superfluid atomic gases were published in scientific journals. This resource article provides a guide to the published experimental studies related to quantized vortices in atomic Bose-Einstein condensates and superfluid Fermi gases. A BibTex-formatted

Brian P. Anderson

2010-01-01

435

Resource Article: Experiments with Vortices in Superfluid Atomic Gases  

Microsoft Academic Search

Observations of quantized vortices in dilute-gas Bose-Einstein condensates were first reported in 1999. Over the next 10 years,\\u000a more than 70 papers describing experiments involving vortices in superfluid atomic gases were published in scientific journals.\\u000a This resource article provides a guide to the published experimental studies related to quantized vortices in atomic Bose-Einstein\\u000a condensates and superfluid Fermi gases. A BibTex-formatted

Brian P. Anderson

2010-01-01

436

Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997.  

PubMed

The evolution of the Earth's climate has been extensively studied, and a strong link between increases in surface temperatures and greenhouse gases has been established. But this relationship is complicated by several feedback processes-most importantly the hydrological cycle-that are not well understood. Changes in the Earth's greenhouse effect can be detected from variations in the spectrum of outgoing longwave radiation, which is a measure of how the Earth cools to space and carries the imprint of the gases that are responsible for the greenhouse effect. Here we analyse the difference between the spectra of the outgoing longwave radiation of the Earth as measured by orbiting spacecraft in 1970 and 1997. We find differences in the spectra that point to long-term changes in atmospheric CH4, CO2 and O3 as well as CFC-11 and CFC-12. Our results provide direct experimental evidence for a significant increase in the Earth's greenhouse effect that is consistent with concerns over radiative forcing of climate. PMID:11268208

Harries, J E; Brindley, H E; Sagoo, P J; Bantges, R J

2001-03-15

437

Robust IR Remote Sensing Technique of the Total Column of Trace Gases Including Carbon Dioxide and Methane  

NASA Technical Reports Server (NTRS)

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.

Georgieva, E. M.; Heaps, W. S.

2011-01-01

438

Biomass Burning and the Production of Greenhouse Gases. Chapter 9  

NASA Technical Reports Server (NTRS)

Biomass burning is a source of greenhouse gases, carbon dioxide, methane, and nitrous oxide. In addition, biomass burning is a source of chemically active gases, including carbon monoxide, nonmethane hydrocarbons, and nitric oxide. These gases, along with methane, lead to the chemical production of tropospheric ozone (another greenhouse gas) as well as control the concentration of the hydroxyl radical, which regulates the lifetime of almost every atmospheric gas. Following biomass burning, biogenic emissions of nitrous oxide, nitric oxide, and methane are significantly enhanced. It is hypothesized that enhanced postburn biogenic emissions of these gases are related to fire-induced changes in soil chemistry and/or microbial ecology. Biomass burning, once believed to be a tropical phenomenon, has been demonstrated by satellite imagery to also be a regular feature of the world's boreal forests. One example of biomass burning is the extensive 1987 fire that destroyed more than 12 million acres of boreal forest in the People's Republic of China and across its border in the Soviet Union. Recent estimates indicate that almost all biomass burning is human-initiated and that it is increasing with time. With the formation of greenhouse and chemically active gases as direct combustion products and a longer-term enhancement of biogenic emissions of gases, biomass burning may be a significant driver for global change.

Levine, Joel S.

1994-01-01

439

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...

440

Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer  

NASA Astrophysics Data System (ADS)

Unique measurements of vertical size resolved aerosol particle concentrations, trace gas concentrations and meteorological data were obtained during the Arctic Summer Cloud Ocean Study (ASCOS, http://www.ascos.se), an International Polar Year project aimed at establishing the processes responsible for formation and evolution of low-level clouds over the high Arctic summer pack ice. The experiment was conducted from onboard the Swedish icebreaker Oden, and provided both ship- and helicopter-based measurements. This study focuses on the vertical helicopter profiles and onboard measurements obtained during a three-week period when Oden was anchored to a drifting ice floe, and sheds light on the characteristics of Arctic aerosol particles and their distribution throughout the lower atmosphere. Distinct differences in aerosol particle characteristics within defined atmospheric layers are identified. Near the surface (lowermost couple hundred meters), transport from the marginal ice zone (MIZ), if sufficiently short (less than ca. 2 days), condensational growth and cloud-processing develop the aerosol population. During two of the four representative periods defined in this study, such influence is shown. At altitudes above about 1 km, long-range transport occurs frequently. However, only infrequently does large-scale subsidence descend such air masses to become entrained into the mixed layer in the high Arctic, and therefore they are unlikely to directly influence low-level stratiform cloud formation. Nonetheless, long-range transport plumes can influence the radiative balance of the PBL by influencing formation and evolution of higher clouds, as well as through precipitation transport of particles downwards. New particle formation was occasionally observed, particularly in the near-surface layer. We hypothesize that the origin of these ultrafine particles can be from biological processes, both primary and secondary, within the open leads between the pack ice and/or along the MIZ. In general, local sources, in combination with upstream boundary layer transport of precursor gases from the MIZ, are suggested to constitute the origin of CCN particles and thus be of importance for the formation of interior Arctic low level clouds during summer, and subsequently, through cloud influences, on the melting and freezing of sea ice.

Kupiszewski, P.; Leck, C.; Tjernström, M.; Sjogren, S.; Sedlar, J.; Graus, M.; Müller, M.; Brooks, B.; Swietlicki, E.; Norris, S.; Hansel, A.

2013-04-01

441

Vertical profiling of aerosol particles and trace gases over the central Arctic Ocean during summer  

NASA Astrophysics Data System (ADS)

Unique measurements of vertical size-resolved aerosol particle concentrations, trace gas concentrations and meteorological data were obtained during the Arctic Summer Cloud Ocean Study (ASCOS, www.ascos.se), an International Polar Year project aimed at establishing the processes responsible for formation and evolution of low-level clouds over the high Arctic summer pack ice. The experiment was conducted from on board the Swedish icebreaker Oden, and provided both ship- and helicopter-based measurements. This study focuses on the vertical helicopter profiles and onboard measurements obtained during a three-week period when Oden was anchored to a drifting ice floe, and sheds light on the characteristics of Arctic aerosol particles and their distribution throughout the lower atmosphere. Distinct differences in aerosol particle characteristics within defined atmospheric layers are identified. Within the lowermost couple hundred metres, transport from the marginal ice zone (MIZ), condensational growth and cloud processing develop the aerosol population. During two of the four representative periods defined in this study, such influence is shown. At altitudes above about 1 km, long-range transport occurs frequently. However, only infrequently does large-scale subsidence descend such air masses to become entrained into the mixed layer in the high Arctic, and therefore long-range transport plumes are unlikely to directly influence low-level stratiform cloud formation. Nonetheless, such plumes can influence the radiative balance of the planetary boundary layer (PBL) by influencing formation and evolution of higher clouds, as well as through precipitation transport of particles downwards. New particle formation was occasionally observed, particularly in the near-surface layer. We hypothesize that the origin of these ultrafine particles could be in biological processes, both primary and secondary, within the open leads between the pack ice and/or along the MIZ. In general, local sources, in combination with upstream boundary-layer transport of precursor gases from the MIZ, are considered to constitute the origin of cloud condensation nuclei (CCN) particles and thus be of importance for the formation of interior Arctic low-level clouds during summer, and subsequently, through cloud influences, for the melting and freezing of sea ice.

Kupiszewski, P.; Leck, C.; Tjernström, M.; Sjogren, S.; Sedlar, J.; Graus, M.; Müller, M.; Brooks, B.; Swietlicki, E.; Norris, S.; Hansel, A.

2013-12-01

442

Quasi-real-time monitoring of SW radiation budget using geostationary satellite for Climate study and Renewable energy. (Invited)  

NASA Astrophysics Data System (ADS)

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.

Takenaka, H.; Nakajima, T. Y.; Kuze, H.; Takamura, T.; Pinker, R. T.; Nakajima, T.

2013-12-01

443

Constraints on the origins of hydrocarbon gas from compositions of gases at their site of origin  

PubMed

It is widely accepted that natural gas is formed from thermal decomposition of both oil in reservoirs and, to a lesser extent, the organic matter in shales from which the oil was derived. But laboratory pyrolysis experiments on shales do not reproduce the methane-rich composition typical of most gas reservoirs, leading to suggestions that other mechanisms, such as transition-metal catalysis, may be important. The discrepancy might, however, instead arise because gas (and oil) deposits have migrated from their source rocks, so that the reservoir composition might not be representative of the composition in the source rocks where the hydrocarbons were generated. To address this question, we have analysed gas samples coproduced with oils directly from a source rock (the Bakken shales, North Dakota, USA) where the local geology has prevented significant hydrocarbon migration. The methane contents of these Bakken-shale gases are much lower than that of conventional gas reservoirs, but are consistent with that from pyrolysis experiments on these shales. Thus, because these Bakken gases form with (rather than from) oils, we argue that compositional differences between gases from source rocks and conventional gas deposits result from fractionation processes occurring after hydrocarbon expulsion from the source rock. PMID:11536709

Price, L C; Schoell, M

1995-11-23

444

Exact few-body results for strongly correlated quantum gases in two dimensions  

NASA Astrophysics Data System (ADS)

The study of strongly correlated quantum gases in two dimensions has important ramifications for understanding many intriguing phenomena in solid materials, such as high- Tc superconductivity and the fractional quantum-Hall effect. However, theoretical methods are plagued by the existence of significant quantum fluctuations. Here, we present two- and three-body exact solutions for both fermions and bosons trapped in a two-dimensional harmonic potential with an arbitrary s -wave scattering length. These few-particle solutions link in a natural way to the high-temperature properties of many-particle systems via a quantum virial expansion. As a concrete example, using the energy spectrum of few fermions, we calculate the second and third virial coefficients of a strongly interacting Fermi gas in two dimensions, and consequently investigate its high-temperature thermodynamics. Our thermodynamic results may be useful for ongoing experiments on two-dimensional Fermi gases. These exact results also provide an unbiased benchmark for quantum Monte Carlo simulations of two-dimensional Fermi gases at high temperatures.

Liu, Xia-Ji; Hu, Hui; Drummond, Peter D.

2010-08-01

445

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

SciTech Connect

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