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1

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

NASA Astrophysics Data System (ADS)

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

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

2000-07-01

2

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

3

Radiation interactions in high-pressure gases  

SciTech Connect

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

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

1990-01-01

4

Interaction with thermal radiation in the free expansion and mixing of ideal gases and Gibbs' paradox in classical thermodynamics  

E-print Network

The standard theory of ideal gases ignores the interaction of the gas particles with the thermal radiation (photon gas) that fills the otherwise vacuum space between them. This is an unphysical feature of the theory since every material in this universe, and hence also the particles of a gas, absorbs and radiates thermal energy. The interaction with the thermal radiation that is contained within the volume of the body may be important in gases since the latter, unlike solids and liquids, are capable of undergoing conspicuous volume changes. Taking this interaction into account makes the behaviour of the ideal gases more realistic and removes Gibbs' paradox.

A. Paglietti

2009-04-26

5

Radiative forcings for 28 potential Archean greenhouse gases  

E-print Network

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

Byrne, Brendan

2014-01-01

6

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

7

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

Microsoft Academic Search

The long-lived greenhouse gases (GHG) are estimated to be the most important driver of climate change over the next century, while aerosols and tropospheric ozone are also expected to induce significant perturbations to the GHG-forced climate. To differentiate the equilibrium climate responses to direct radiative forcing from changes in anthropogenic aerosols, tropospheric ozone, and GHG between present day and year

W. Chen; H. Liao; J. H. Seinfeld

2006-01-01

8

Stratospheric radiation, dynamics and trace gases in an idealized GCM  

NASA Astrophysics Data System (ADS)

Stratospheric radiation, dynamics, and trace gas distributions form a complex, coupled system. It is therefore difficult to establish direct cause-and-effect relationships between different variables, in both observations and comprehensive numerical models. We employ an idealized model to disentangle effects of radiation, dynamics and tracer transport. Besides the advantages in terms of hardware requirement, such models can advance understanding by testing basic theories and processes. We seek to determine the limits of such simple frameworks, outside which more complex models are needed to investigate the underlying mechanisms. Here, we will concentrate on the effect of dynamics through transport and temperature on water vapor and ozone, and the feedback of these tracers on dynamics via radiation. While water vapor response on dynamics is weak, the impact of dynamics on it is strong. Specifically, the see-saw of tropical and polar vortex temperatures, driven by insolation and dynamics, constrains water vapor in the stratosphere. Conversely, ozone acts strongly on dynamics, and we discuss important aspects of this feedback beyond the ozone hole. As a potent greenhouse gas and chemical agent, understanding the variation in water vapor distribution under changing dynamics is essential for future trend estimations. The radiative effect of ozone, on the other hand, has mainly received attention in the context of the ozone hole, cooling and strengthening the polar vortex, but it can also play its part in the seasonal cycle of tropical temperatures.

Jucker, M.; Fueglistaler, S.; Vallis, G. K.

2012-12-01

9

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

NASA Technical Reports Server (NTRS)

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

Wood, A. D.

1969-01-01

10

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

11

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

12

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

13

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

Microsoft Academic Search

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

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

2007-01-01

14

Filling of glass microshells with heavy gases by radiation-simulated diffusion  

Microsoft Academic Search

The research results of an opportunity of radiation-stimulated diffusion use for laser fusion microtargets filling with heavy gases are given, which they can not be filled with by means of usual diffusion. The theoretical estimates of quantity and character of radiation damages, their distribution in the volume of an irradiated material are made. The calculations of glass microshells argon filling

V. M. Izgorodin; S. N. Abramovich; V. G. Gogolev; N. V. Zhidkov; Yu V. Ignat'ev; A. E. Lakhtikov; A. P. Morovov; G. P. Nikolayev; V. N. Protopopov; V. T. Punin; V. A. Starodubtsev; B. V. Ferapontov; Yu. N. Khirnii; Yu. A. Khokhlov; V. V. Chulkov

2003-01-01

15

DIFFERENTIAL TOTAL ABSORPTIVITY SOLUTION TO THE RADIATIVE TRANSFER EQUATION FOR MIXTURES OF COMBUSTION GASES AND SOOT  

Microsoft Academic Search

The differential total absorptivity (DTA) solution to the radiative transfer equation, originally devised for combustion gases in the discrete transfer radiation model, is extended to mixtures of gaseous combustion products and soot. The method is compared to other solution techniques for representative mixtures across single lines of sight and across a layer bounded by solid walls. Intermediate soot loadings are

N. W. Bressloff; J. B. Moss; P. A. Rubini

1997-01-01

16

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

17

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

18

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

19

The Importance of Ecosystem Thresholds in Assessing Safe Concentrations of Greenhouse Gases  

NASA Astrophysics Data System (ADS)

There is a major strategic challenge in the public debate about global environmental change related to concentrations of greenhouse gases in the atmosphere that might lead to environmentally, socially, and economically unacceptable impacts. This project takes one approach to this problem: avoiding "dangerous anthropogenic interference" and "allowing ecosystems to adapt." But these phrases implicitly assume that the influences of climate change are likely to be gradual and that there will be substantial time for natural resources to adapt or for managers to cope with change. The current state of the science suggests that something quite different may be in the offing. The Intergovernmental Panel on Climate Change (IPCC) and other assessments of possible impacts now agree on two important points. One is that there is already well-documented evidence of the biological and ecological consequences of climate change - in the behavior of migratory birds, in corals bleached from the influence of warming ocean temperatures, in the loss of glaciers to warming air temperatures, and in the loss of sea grass beds to sea level rise. The second is that ecological systems may not in fact change gradually. Modeling studies and the historical record both suggest that changes in ecosystems can be rapid, large, and sometimes irreversible, i.e., there are thresholds that, once crossed, will present serious coping challenges to humans. Moreover, as suggested in a recent National Academy of Sciences (NAS) workshop on "Understanding and Responding to Multiple Environmental Stresses," dealing with threshold responses that may lead to sudden and dramatic change in societal or environmental structure and function will also require that we develop ways to proceed with decision-making despite the many uncertainties associated with thresholds. These observations present serious challenges to the modeling frameworks used in integrated assessment. Not only do the models have to characterize the dynamic behavior of ecosystems as they cross thresholds, but they also have to represent adaptation strategies that are promoted to cope with such sudden or irreversible changes. A major challenge in the discussion over the implications of tipping points and thresholds in natural resources and management systems is what lessons there are for debates over targets for concentrations of greenhouse gases in the atmosphere. Are there levels of greenhouse gases that would protect against ecosystems exhibiting tipping point behavior, for example? How does uncertainty in our knowledge of either the resources or the climate system influence margins of safety? What models and analytical tools are available for conducting the analyses that are needed to address these questions. The JGCRI's suite of integrated assessment models provide a systematic way of simulating different emissions and concentration scenarios that can then be used to investigate the climate triggers for ecological tipping points and thresholds.

Janetos, A. C.

2007-12-01

20

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

21

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

22

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

23

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

24

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

25

Clinically important radiation-associated thyroid disease  

Microsoft Academic Search

We evaluated 1266 persons who had received external radiotherapy for benign diseases in childhood. The evaluation used detailed questionnaires completed by trained interviewers and neoplastic disease registry data. The control population included 958 age-, sex-, race-, and disease-matched persons who had not received radiotherapy and 9865 family members of the two study groups. An excess number of clinically important thyroid

H. R. Maxon; E. L. Saenger; S. R. Thomas; C. R. Buncher; J. G. Kereiakes; M. L. Shafer; C. A. McLaughlin

1980-01-01

26

Clinically important radiation-associated thyroid disease  

SciTech Connect

We evaluated 1266 persons who had received external radiotherapy for benign diseases in childhood. The evaluation used detailed questionnaires completed by trained interviewers and neoplastic disease registry data. The control population included 958 age-, sex-, race-, and disease-matched persons who had not received radiotherapy and 9865 family members of the two study groups. An excess number of clinically important thyroid neoplasms, both benign and malignant, was noted in the irradiated group.

Maxon, H.R.; Saenger, E.L.; Thomas, S.R.; Buncher, C.R.; Kereiakes, J.G.; Shafer, M.L.; McLaughlin, C.A.

1980-10-17

27

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

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

2012-01-01

28

Photoionization in rare gases with synchrotron radiation: Some basic aspects for critical tests with theory  

NASA Astrophysics Data System (ADS)

Three different aspects of angle-resolved electron spectrometry using synchrotron radiation are discussed on the basis of three specific examples: the line resolution, the kinetic energy and the angular distribution parameter. It is shown that for rare gases data of high quality can be obtained such that the data provide the basis for critical tests with different theoretical treatments. The selected examples concern the 3 s/3 p satellite spectrum of argon, the influence of post-collision interaction in the electron spectrum related to 4 d-photoionization in xenon and the angular distribution parameter for 2 p-photoionization in neon.

Schmidt, V.

1986-12-01

29

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

30

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

31

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

32

Shock formation from the interaction of supersonic, radiatively cooled plasma flows with neutral gases  

NASA Astrophysics Data System (ADS)

The dynamics of the interaction of supersonic, radiatively cooled plasma flows with applications to laboratory astrophysics are under study on the MAGPIE generator. One of such astrophysical-relevant experiments is the ablated plasma from a radial foil, with typical flow velocities reaching ˜100 km/s. The effect of the ambient medium is studied by adding neutral gases, either using a supersonic gas-nozzle or by enclosing the foil inside a gas-cell. In both cases, the dynamics of the interaction are characterized by the formation of several shock features. Experimental results varying ambient parameters such as gas pressure and gas composition (e.g. He, Ar, Xe) will be presented together with 3-D MHD simulations using the code GORGON.

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

2012-10-01

33

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

Microsoft Academic Search

The Spectral Line-based Weighted-Sum-of-Gray-Gases (SLWSGG) model is applied to calculate the gaseous radiative properties of the aero- or oxy-combustion products of low heating value gases issued from steel making process such as Blast Furnace Gas (BFG) as well as of high heating value gases such as Coke Oven Gas (COG) and conventional Natural Gas (NG). The comparison of total emissivities

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

2012-01-01

34

Importance of radiation field screening in XPS and XAFS spectra  

NASA Astrophysics Data System (ADS)

In this work the importance of radiation field screening is stressed in Keldysh's Green's function theory to study X-ray photoelectron spectroscopy (XPS) spectra and X-ray absorption fine structure (XAFS). So far these terms have been supposed to be small, however, we have found that these effects play a crucial role to analyze resonance effects. In particular the importance of these vertex correction is important in the analyses of multiatom resonant photoemission (MARPE) spectra and the resonance effects in XAFS. We also investigate the contribution from polarized part Wp of the screened Coulomb interaction W to the resonance effects. We find that W? v is quite a good approximation. Off the resonance these radiation field screening diagrams are not important. They have no contribution to loss processes even though they include W> and W<.

Fujikawa, Takashi; Arai, Hiroko

2003-01-01

35

Radiation monitoring of imported food to Saudi Arabia after Chernobyl  

SciTech Connect

Saudi Arabia has been indirectly affected by the Chernobyl accident. Large amounts of food or products that may enter the food chain are daily imported from European countries. After April 27, the Saudi government assigned the responsibilities of radiation monitoring of imported food to some universities and governmental sectors. The nuclear engineering department at King Abdulaziz Univ. (KAU) has undertaken the monitoring duties for products coming to western and southern provinces of the country. The sampling and monitoring procedures and results are described.

Abulfaraj, W.H.; Abdul-Majid, S.; Abdul-Fattah, A.F.

1987-01-01

36

Studies of supersonic, radiative plasma jet interaction with gases at the Prague Asterix Laser System facility  

SciTech Connect

The interaction of laser driven jets with gas puffs at various pressures is investigated experimentally and is analyzed by means of numerical tools. In the experiment, a combination of two complementary diagnostics allowed to characterize the main structures in the interaction zone. By changing the gas composition and its density, the plasma cooling time can be controlled and one can pass from a quasiadiabatic outflow to a strongly radiation cooling jet. This tuning yields hydrodynamic structures very similar to those seen in astrophysical objects; the bow shock propagating through the gas, the shocked materials, the contact discontinuity, and the Mach disk. From a dimensional analysis, a scaling is made between both systems and shows the study relevance for the jet velocity, the Mach number, the jet-gas density ratio, and the dissipative processes. The use of a two-dimensional radiation hydrodynamic code, confirms the previous analysis and provides detailed structure of the interaction zone and energy repartition between jet and surrounding gases.

Nicolaie, Ph.; Stenz, C.; Tikhonchuk, V.; Ribeyre, X.; Galera, S.; Schurtz, G. [Centre Lasers Intenses et Applications, Universite Bordeaux 1-CNRS-CEA, 33405 Talence Cedex (France); Kasperczuk, A.; Pisarczyk, T. [Institute of Plasma Physics and Laser Microfusion, 00-908 Warsaw (Poland); Klir, D.; Kravarik, J.; Kubes, P. [Czech Technical University in Prague, FEL, Technicka 2, 166 27 Prague 6 (Czech Republic); Juha, L.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J. [Institute of Physics ASCR, v.v.i. Na Slovance 2, 182 21 Prague 8 (Czech Republic); Ullschmied, J. [Institute of Plasma Physics ASCR, v.v.i. Za Slovankou 3, 182 00 Prague 8 (Czech Republic); Kalal, M. [Czech Technical University in Prague, FNSPE, Brehova 7, 115 19 Prague 1 (Czech Republic); Pisarczyk, P. [Warsaw University of Technology, ICS, 00-665, Warsaw (Poland)] (and others)

2008-08-15

37

High frequency of fumigants and other toxic gases in imported freight containers--an underestimated occupational and community health risk.  

PubMed

Residues of pesticide fumigants and toxic industrial chemicals in freight containers represent a health hazard to employees and consumers, especially since freight containers are sealed for transport and distributed widely throughout the importing countries before being opened for unloading. We investigated 2113 freight containers arriving at the second largest container terminal in Europe, Hamburg, Germany, over a 10-week period in 2006. The countries of origin, type of contents and the pesticide fumigation history declared on labels attached to the container were recorded. We determined that 1478 (70%) containers were contaminated with toxic chemicals above chronic reference exposure levels; 761 (36%) even exceeded the higher acute reference exposure level thresholds. Benzene and/or formaldehyde contamination was 4-times greater than for fumigants. Our findings indicate a health risk for dockworkers, container unloaders and even end-consumers, especially as many of the cancerogenic or toxic gases elude subjective detection. PMID:19858536

Baur, Xaver; Poschadel, Bernd; Budnik, Lygia Therese

2010-03-01

38

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

39

Radiation-induced cell death: importance of lysosomal destabilization  

PubMed Central

The mechanisms involved in radiation-induced cellular injury and death remain incompletely understood. In addition to the direct formation of highly reactive hydroxyl radicals (HO·) by radiolysis of water, oxidative stress events in the cytoplasm due to formation of H2O2 may also be important. Since the major pool of low-mass redox-active intracellular iron seems to reside within lysosomes, arising from the continuous intralysosomal autophagocytotic degradation of ferruginous materials, formation of H2O2 inside and outside these organelles may cause lysosomal labilization with release to the cytosol of lytic enzymes and low-mass iron. If of limited magnitude, such release may induce ‘reparative autophagocytosis’, causing additional accumulation of redox-active iron within the lysosomal compartment. We have used radio-resistant histiocytic lymphoma (J774) cells to assess the importance of intralysosomal iron and lysosomal rupture in radiation-induced cellular injury. We found that a 40 Gy radiation dose increased the ‘loose’ iron content of the (still viable) cells approx. 5-fold when assayed 24 h later. Cytochemical staining revealed that most redox-active iron was within the lysosomes. The increase of intralysosomal iron was associated with ‘reparative autophagocytosis’, and sensitized cells to lysosomal rupture and consequent apoptotic/necrotic death following a second, much lower dose of radiation (20 Gy) 24 h after the first one. A high-molecular-mass derivative of desferrioxamine, which specifically localizes intralysosomally following endocytic uptake, added to the culture medium before either the first or the second dose of radiation, stabilized lysosomes and largely prevented cell death. These observations may provide a biological rationale for fractionated radiation. PMID:15813701

2005-01-01

40

GaSe and GaTe anisotropic layered semiconductors for radiation detectors  

NASA Astrophysics Data System (ADS)

High quality detector grade GaSe and GaTe single crystals have been grown by a modified vertical Bridgman technique using high purity Ga (7N) and in-house zone refined (ZR) precursor materials (Se and Te). A state-of-the-art computer model, MASTRAPP, is used to model heat and mass transfer in the Bridgman growth system and to predict the stress distribution in the as-grown crystals. The model accounts for heat transfer in the multiphase system, convection in the melt, and interface dynamics. The crystals harvested from ingots of 8-10 cm length and 2.5 cm diameter, have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, low temperature photoluminescence (PL), atomic force microscopy (AFM), and optical absorption/transmission measurements. Single element devices up to 1 cm2 in area have been fabricated from the crystals and tested as radiation detectors by measuring current-voltage (I-V) characteristics and pulse height spectra using 241Am source. The crystals have shown high promise as nuclear detectors with their high dark resistivity (>=10 9 ? .cm), good charge transport properties (?? e ~ 1.4x10 -5 cm2/V and ?? h ~ 1.5x10 -5 cm2/V), and relatively good energy resolution (~4% energy resolution at 60 keV). Details of numerical modeling and simulation, detector fabrication, and testing using a 241Am energy source (60 keV) is presented in this paper.

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

2007-09-01

41

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

42

Importance of instantaneous radiative forcing for rapid tropospheric adjustment  

NASA Astrophysics Data System (ADS)

To better understand CFMIP/CMIP inter-model differences in rapid low cloud responses to CO2 increases and their associated effective radiative forcings, we examined the tropospheric adjustment of the lower tropospheric stability (LTS) in three general circulation models (GCMs): HadGEM2-A, MIROC3.2 medres, and MIROC5. MIROC3.2 medres showed a reduction in LTS over the sub-tropical ocean, in contrast to the other two models. This reduction was consistent with a temperature decrease in the mid-troposphere. The temperature decrease was mainly driven by instantaneous radiative forcing (RF) caused by an increase in CO2. Reductions in radiative and latent heating, due to clouds, and in adiabatic and advective heating, also contribute to the temperature decrease. The instantaneous RF in the mid-troposphere in MIROC3.2 medres is inconsistent with the results of line-by-line (LBL) calculations, and thus it is considered questionable. These results illustrate the importance of evaluating the vertical profile of instantaneous RF with LBL calculations; improved future model performance in this regard should help to increase our confidence in the tropospheric adjustment in GCMs.

Ogura, Tomoo; Webb, Mark J.; Watanabe, Masahiro; Lambert, F. Hugo; Tsushima, Yoko; Sekiguchi, Miho

2014-09-01

43

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

44

IMPORTANCE OF TURBULENCE-RADIATION INTERACTIONS IN TURBULENT REACTING FLOWS  

Microsoft Academic Search

Traditional modeling of radiative transfer in reacting flows has ignored turbulence-radiation interactions (TRI). Radiative fluxes, flux divergences and radiative properties have been based on mean temperature and concentration fields. However, both experimental and theoretical work have suggested that mean ra- diative quantities may di er significantly from those predictions based on the mean parameters because of their strongly non- linear

Genong Li; Michael F. Modest

2002-01-01

45

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 studentsâ 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.

46

Homogeneous and heterogeneous radiation induced NO and SO 2 removal from power plants flue gases—modeling study  

NASA Astrophysics Data System (ADS)

The generalized mathematical model has been developed for radiation induced removal of NO and SO 2 from flue gases of power plants. This model includes energy absorption of electron beam with active species generation, reactions in gas phase, aerosol formation and growth, and liquid-phase chemistry. To investigate the role of various process parameters (initial NO and SO 2 concentrations, temperature, humidity, absorbed dose) a number of numerical calculations has been carried out. Computer modeling results are in good agreement with reported experimental data.

Gerasimov, G. Y.; Gerasimova, T. S.; Makarov, V. N.; Fadeev, S. A.

1996-12-01

47

[Radiation-induced bystander effect: the important part of ionizing radiation response. Potential clinical implications].  

PubMed

It has long been a central radiobiological dogma that the damaging effects of ionizing radiation, such as cell death, cytogenetic changes, apoptosis, mutagenesis, and carcinogenesis, are the results of the direct ionization of cell structures, particularly DNA, or indirect damage via water radiolysis products. However, several years ago attention turned to a third mechanism of radiation, termed the "bystander effect" or "radiation-induced bystander effect" (RIBE). This is induced by agents and signals emitted by directly irradiated cells and manifests as a lowering of survival, cytogenetic damage, apoptosis enhancement, and biochemical changes in neighboring non-irradiated cells. The bystander effect is mainly observed in in vitro experiments using very low doses of alpha particles (range; mGy, cGy), but also after conventional irradiation (X-rays, gamma rays) at low as well as conventional doses. The mechanisms responsible for the bystander effect are complex and still poorly understood. It is believed that molecular signals released from irradiated cells induce different signaling ways in non-irradiated neighboring cells, leading to the observed events. The molecular signals may be transmitted through gap junction intercellular communication and through a medium transfer mechanism. The nature of these transmitted factors are diverse, and still not definitely established. It seems that RIBE may have important clinical implications for health risk associated with radiation exposure. Potentially, this effect may have important implications in the creation of whole-body or localized side effects in tissues beyond the irradiation field and also in low-dose radiological and radioisotope diagnostics. Factors emitted by irradiated cells may result in the risk of genetic instability, mutations, and second primary cancer induction. They might also have their own part in inducing and extending post-radiation side effects in normal tissue. The bystander effect may be a potentially harmful or a useful event in radiotherapy. The elevation of damage to tumor cells not directly hit by radiation or the initiation of tumor cell differentiation may increase the therapeutic ratio. If, however, molecular species secreted by irradiated tumor cells in vivo damage neighboring normal cells (epithelial and endothelial cells, fibroblasts, or lymphocytes), the bystander effect would be harmful and could lead to increased side effects in normal tissue. This is especially important in modern radiotherapy, as 3D conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT) are aimed at diminishing the radiation dose in normal tissues. Recent in vivo studies on animals indicate that bystander effects may appear in organs and tissues remote from the irradiated field and the extension of tissue damage seems to be tissue-type dependent. However, recent experimental results indicate that non-irradiated cells that are neighbors of irradiated cells may diminish radiation damage in the radiation-focused cells. Less is known about the bystander effect during fractionated irradiation. Thus the clinical implications of the bystander effect and its possible modification for radiotherapeutic usefulness is still under debate. PMID:19724078

Wide?, Maria; Przybyszewski, Waldemar; Rzeszowska-Wolny, Joanna

2009-01-01

48

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

NASA Astrophysics Data System (ADS)

Since 1979, sensors on board the National Oceanic and Atmospheric Administration (NOAA) series of polar meteorological satellites have provided continuous measurements of the earth's surface and atmosphere. One of these sensors, the Television Infrared Observational Satellite (TIROS-N) Operational Vertical Sounder (TOVS), observes earth-emitted radiation in the infrared-with the High-Resolution Infrared Sounder (HIRS)-and in the microwave-with the Microwave Sounding Unit (MSU)-portions of the spectrum. The NOAA and National Aeronautics and Space Administration (NASA) Pathfinder program was designed to make these data more readily accessible to the community in the form of processed geophysical variables (temperature, water vapor, cloud characteristics, and so on) through the `interpretation' of the infrared and microwave radiances. All presently developed interpretation algorithms more or less directly rely on the comparison between a set of observed and a set of simulated radiances. For that reason, the accuracy of the simulation directly influences that of the interpretation of radiances in terms of thermodynamic variables. Comparing simulations to observations is the key to a better knowledge of the main sources of errors affecting either the former or the latter. Instrumental radiometric problems, radiosonde, surface data, and forward radiative transfer model limitations as well as difficulties raised by differences in space and in time of satellite and radiosonde observations (collocations) have long been studied in detail. Less attention has been paid to errors, presumed negligible, generated by the absence of consideration of main absorbing gases (CO2, N2O, CO, O3, and so on) atmospheric seasonal cycles and/or annual trends. In this paper, all important sources of variability of the observations and of the simulations are first reviewed. Then it is shown that analyzing, at different timescales (seasonal, annual), the departures between simulated and observed NOAA TOVS brightness temperatures reveals signatures of these greenhouse gases' concentration variations. Not only the shape of the seasonal variations (locations of the peaks) is in good agreement with what is presently known, but also their amplitude (peak-to-peak) matches relatively well the values predicted from a line-by-line radiative transfer model. Moreover, annual trends correspond very well with the known increase in concentration of gases such as CO2 or N2O, as a result of human activities. Limits of such an analysis are discussed: the most significant one finds its origin in the modest spectral resolution of the TOVS channels that integrate signatures from several absorbers and from many atmospheric layers. However, results from this work leave some hope to extract from these channels interesting information on CO2, N2O, and CO distributions. These results also strengthen the hope to improve greatly the knowledge of the global distribution of a variety of radiatively active gases with the coming second generation of vertical sounders such as NASA's Advanced Infrared Radiation Sounder (AIRS) or the CNES/Eumetsat Infrared Atmospheric Sounder Interferometer (IASI), both characterized by a much higher spectral resolution.

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

2002-01-01

49

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

50

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

51

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

52

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

NASA Technical Reports Server (NTRS)

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

Bogdanoff, David W.; Park, Chul

2001-01-01

53

Sequential two-photon double ionization of noble gases by circularly polarized XUV radiation  

NASA Astrophysics Data System (ADS)

Photoelectron angular distributions (PADs) and angular correlations between two emitted electrons in sequential two-photon double ionization (2PDI) of atoms by circularly polarized radiation are studied theoretically. In particular, the sequential 2PDI of the valence n{{p}6} shell in noble gas atoms (neon, argon, krypton) is analyzed, accounting for the first-order corrections to the dipole approximation. Due to different selection rules in ionization transitions, the circular polarization of photons causes some new features of the cross sections, PADs and angular correlation functions in comparison with the case of linearly polarized photons.

Gryzlova, E. V.; Grum-Grzhimailo, A. N.; Kuzmina, E. I.; Strakhova, S. I.

2014-10-01

54

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

55

Dynamic, radiative and chemical effects of clouds on tropospheric trace gases  

NASA Astrophysics Data System (ADS)

It is demonstrated that calculations of regional or global tropospheric chemistry models are sensitive to the treatment of the microphysical and dynamical structure of clouds, suggesting the need for accurate models of these cloud effects in global and regional chemical models. Model results suggest that vertical motions associated with midlatitude cyclones over high NOx and organic compound emission areas can contribute significantly to the global formation of O3 since the necessary precursors are efficiently transported into the upper troposphere, where the lifetimes of these O3 precursors are much longer, and photolysis rates are significantly enhanced due to lower-level cloud fields. Regional-scale O3 production rates are extremely sensitive to the vertical and horizontal extent of cloudiness, as well as the microphysical structure of these clouds. Calculations of a radiative transfer model show that photolysis rates above clouds may be significantly enhanced, while below clouds, photolysis rates can be reduced to near zero. Since photolysis rates determine the rate at which tropospheric photochemistry is occurring, it is clear that models of tropospheric chemistry must accurately quantify the microphysics and dynamics of tropospheric cloud fields.

Walcek, Chris J.

56

Radiative forcing at high concentrations of well-mixed greenhouse gases  

NASA Astrophysics Data System (ADS)

We present new calculations of radiative forcing at very high concentrations of CO2, CH4, and N2O, relevant to extreme anthropogenic climate change and paleoclimate studies. CO2 forcing is calculated over the range 100 ppmv to 50,000 ppmv, and the maximum forcing is 38.1 W m-2. CH4 and N2O forcings are calculated over the range 100 ppbv to 100 ppmv and give maximum forcings of 6.66 W m-2 and 22.3 W m-2. The sensitivity of our calculations to spatial averaging and tropopause definition is examined. We compare our results with the "simplified expressions" reported by Intergovernmental Panel on Climate Change (IPCC) and find significant differences at high greenhouse gas concentrations. We provide new simplified expressions which agree much better with the calculated forcings and suggest that these expressions be used in place of the IPCC expressions. Additionally, we provide meridionally resolved forcings which may be used to force simple and intermediate complexity climate models.

Byrne, B.; Goldblatt, C.

2014-01-01

57

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

E-print Network

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

Haugen, Nils Erland L

2014-01-01

58

The evolution of synchrotron radiation and the growth of its importance in crystallography  

Microsoft Academic Search

The author's 2011 British Crystallographic Association Lonsdale Lecture included a tribute to Kathleen Lonsdale followed by detailed perspectives relevant to the title, with reference to the Synchrotron Radiation Source (SRS) and European Synchrotron Radiation Facility (ESRF). Detector initiatives have also been very important as have sample freezing cryomethods. The use of on-resonance anomalous scattering, smaller crystals, ultra-high resolution as well

John R. Helliwell

2012-01-01

59

The evolution of synchrotron radiation and the growth of its importance in crystallography  

Microsoft Academic Search

The author's 2011 British Crystallographic Association Lonsdale Lecture included a tribute to Kathleen Lonsdale followed by detailed perspectives relevant to the title, with reference to the Synchrotron Radiation Source (SRS) and European Synchrotron Radiation Facility (ESRF). Detector initiatives have also been very important as have sample freezing cryomethods. The use of on-resonance anomalous scattering, smaller crystals, ultra-high resolution as well

John R. Helliwell

2011-01-01

60

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

61

Retrieval and Analysis of Temperature and Important Trace Gases in the Lower Stratosphere as measured by GLORIA during ESSenCe11  

NASA Astrophysics Data System (ADS)

The Gimballed Limb Observer for Radiance Imaging in the Atmosphere (GLORIA) is a new remote sensing instrument combining a Fourier transform infrared spectrometer with a highly flexible gimbal mount. The 2-D detector array measures spectra with a uniquely spatial and spectral resolution. Air masses can be observed from different directions by turning the instrument's line of sight in the gimbal frame. During December 2011 the instrument flew for the first time on the high flying Russian Geophysica M-55 research plane over Kiruna (Sweden). At that time, there was a very strong and cold polar vortex with several filamentary structures at its boundary and within the operation radius of the aircraft. We retrieved fields of temperature and several important trace gases from measurements obtained during the ESSenCe campaign and compared them to 3-D model calculations of the atmosphere. We show that there exists filamentary structure of less than 1 km vertical extent, which is only visible due to the high vertical resolution of 300 m provided by GLORIA and is not fully resolved in the comparison data.

Blank, Jörg; Guggenmoser, Tobias; Ungermann, Jörn; Grooß, Jens-Uwe; Vogel, Baerbel; Kleinert, Anne; Kaufmann, Martin; Riese, Martin

2013-04-01

62

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

63

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

64

[Organ-limited prostate cancer with positive resection margins. Importance of adjuvant radiation therapy].  

PubMed

For pT3 prostate cancer with positive resection margins, the importance of postoperative radiation therapy is confirmed by a high level of evidence. However, for the pT2,R1 situation prospective, randomized studies concerning this question are lacking. Despite better local tumor control in the pT2 stage the PSA recurrence rate lies between 25% and 40% and positive margins are an independent factor for recurrence. Retrospective studies suggest a positive effect of adjuvant or salvage radiation for the oncological outcome in the pT2,R1 situation. On the other hand the side effects profile, with a potentially negative influence of postoperative continence and various delayed toxicities, is not insignificant despite modern radiation techniques and in the era of ultrasensitive PSA analysis should be considered in the risk-benefit assessment. As long as the optimal initiation of postoperative radiation therapy is unclear, the assessment of indications for adjuvant or salvage radiation for organ-limited prostate cancer with positive resection margins should be made after an individual patient consultation and under consideration of the recurrence risk factors, such as the Gleason grade and the localization and extent of the resection margins. PMID:22526182

Porres, D; Pfister, D; Brehmer, B; Heidenreich, A

2012-09-01

65

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

NASA Astrophysics Data System (ADS)

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

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

2005-07-01

66

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

67

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

California at Santa Cruz, University of

68

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

PubMed

As part of a study funded by NASA MSFC to assess thecontribution of secondary particles in producing radiation damage to optoelectronics devices located on the International Space Station (IS), Monte Carlo calculations have been made to predict secondary spectra vs. shielding inside ISS modules and in electronics boxes attached on the truss (Armstrong and Colborn, 1998). The calculations take into account secondary neutron, proton, and charged pion production from the ambient galactic cosmic-ray (GCR) proton, trapped proton, and neutron albedo environments. Comparisons of the predicted neutron spectra with measurments made on the Mir space station and other spacecraft have also been made (Armstrong and Colborn, 1998). In this paper, some initial results from folding the predicted neutron spectrum inside ISS modules from Armstrong and Colborn (1998) with several types of radiation effects response functions related to electronics damage and astronaut-dose are given. These results provide an estimate of the practical importance of neutrons compared to protons in assessing radiation effects for the ISS. Also, the important neutron energy ranges for producing these effects have been estimated, which provides guidance for onboard neutron measurement requirements. PMID:11852942

Armstrong, T W; Colborn, B L

2001-06-01

69

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

E-print Network

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

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

2006-07-17

70

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

71

Importance of Compton scattering to radiation spectra of isolated neutron stars  

E-print Network

Model atmospheres of isolated neutron stars with low magnetic field are calculated with Compton scattering taking into account. Models with effective temperatures 1, 3 and 5 MK, with two values of surface gravity log(g)g = 13.9 and 14.3), and different chemical compositions are calculated. Radiation spectra computed with Compton scattering are softer than the computed with Thomson scattering at high energies (E > 5 keV) for hot (T_eff > 1 MK) atmospheres with hydrogen-helium composition. Compton scattering is more significant to hydrogen models with low surface gravity. The emergent spectra of the hottest (T_eff > 3 MK) model atmospheres can be described by diluted blackbody spectra with hardness factors ~ 1.6 - 1.9. Compton scattering is less important for models with solar abundance of heavy elements.

V. Suleimanov; K. Werner

2006-12-22

72

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

73

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

74

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

75

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

76

Flammability of methane, propane, and hydrogen gases  

Microsoft Academic Search

This paper reports the results of flammability studies for methane, propane, hydrogen, and deuterium gases in air conducted by the Pittsburgh Research Laboratory. Knowledge of the explosion hazards of these gases is important to the coal mining industry and to other industries that produce or use flammable gases. The experimental research was conducted in 20 L and 120 L closed

Kenneth L. Cashdollar; Isaac A. Zlochower; Gregory M. Green; Richard A. Thomas; Martin Hertzberg

2000-01-01

77

Climate-chemical interactions and effects of changing atmospheric trace gases  

Microsoft Academic Search

The problem concerning the greenhouse effects of human activities has broadened in scope from the CO2-climate problem to the trace gas-climate problem. The climate effects of non-CO2 trace gases are strongly governed by interactions between chemistry, radiation, and dynamics. We discuss in detail the nature of the trace gas radiative heating and describe the importance of radiative-chemical interactions within the

V. Ramanathan; L. Callis; R. Cess; J. Hansen; I. Isaksen; W. Kuhn; A. Lacis; F. Luther; J. Mahlman; R. Reck; M. Schlesinger

1987-01-01

78

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

79

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

80

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.

Consortium, The C.

2011-12-13

81

Biomarkers and surrogate endpoints for normal-tissue effects of radiation therapy: the importance of dose-volume effects  

PubMed Central

Biomarkers are of interest for predicting or monitoring normal tissue toxicity of radiation therapy. Advances in molecular radiobiology provide novel leads in the search for normal tissue biomarkers with sufficient sensitivity and specificity to become clinically useful. This paper reviews examples of studies of biomarkers as predictive markers, as response markers or as surrogate endpoints for radiation side-effects. Single nucleotide polymorphisms (SNPs) are briefly discussed in the context of candidate gene and genome wide association studies. The importance of adjusting for radiation dose distribution in normal tissue biomarker studies is underlined. Finally, research priorities in this field are identified and discussed. PMID:20171510

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

2012-01-01

82

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

83

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

84

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

NASA Astrophysics Data System (ADS)

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.

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

2013-08-01

85

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

86

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

87

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

Microsoft Academic Search

Air traffic condensation trails, or contrails, are believed to have a net atmospheric warming effect(1), 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(2). Contrails have an effect on the

Nicola Stuber; Piers Forster; G. Radel; Keith Shine

2006-01-01

88

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

89

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

90

General relativistic magnetohydrodynamic simulations of accretion on to Sgr A*: how important are radiative losses?  

NASA Astrophysics Data System (ADS)

We present general relativistic magnetohydrodynamic numerical simulations of the accretion flow around the supermassive black hole in the Galactic Centre, Sagittarius A* (Sgr A*). The simulations include for the first time radiative cooling processes (synchrotron, bremsstrahlung and inverse Compton) self-consistently in the dynamics, allowing us to test the common simplification of ignoring all cooling losses in the modelling of Sgr A*. We confirm that for Sgr A*, neglecting the cooling losses is a reasonable approximation if the Galactic Centre is accreting below ˜10-8 M? yr-1, i.e. M?<10-7M? Edd . However, above this limit, we show that radiative losses should be taken into account as significant differences appear in the dynamics and the resulting spectra when comparing simulations with and without cooling. This limit implies that most nearby low-luminosity active galactic nuclei are in the regime where cooling should be taken into account. We further make a parameter study of axisymmetric gas accretion around the supermassive black hole at the Galactic Centre. This approach allows us to investigate the physics of gas accretion in general, while confronting our results with the well-studied and observed source, Sgr A*, as a test case. We confirm that the nature of the accretion flow and outflow is strongly dependent on the initial geometry of the magnetic field. For example, we find it difficult, even with very high spins, to generate powerful outflows from discs threaded with multiple, separate poloidal field loops.

Dibi, S.; Drappeau, S.; Fragile, P. C.; Markoff, S.; Dexter, J.

2012-11-01

91

On the importance of prompt oxygen changes for hypofractionated radiation treatments  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

92

The Importance of Technical Reachback in the Adjudication of Radiation Alarms  

SciTech Connect

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

Buckley, W M; Allen, R W

2009-03-18

93

Characterization of space radiation environment in terms of the energy deposition in functionally important volumes  

SciTech Connect

Since the damage which initiates detrimental effects occurs in a small site (semiconductor junctions, or biological cell nuclei), these differences in spatial distribution of ionization maybe the relevant factor controlling the effectiveness of different radiations. Again, when the appropriate cross section data are available Monte Carlo methods can be used to simulate the positions of all ionizations and excitations produced by a typical charged particle. This calculated track structure must interact with the biological or electronic entity in which it occurs to produce the effect. However, we do not know the mechanisms of this interaction and thus cannot specify which characteristics of the charged particle track are responsible for the relevant damage. From track structure we can obtain the spectrum of energy deposition in small volumes which may be relevant to the processes of concern. This has lead to a new approach to dosimetry, one which emphasizes the stochastic nature of energy deposition in small sites, known as microdosimetry. 6 refs., 4 figs.

Braby, L.A.; Metting, N.F.; Wilson, W.E.; Ratcliffe, C.A.

1988-01-01

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

1986-01-01

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, S.; Kulkarni, S.S.

1986-08-26

96

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

SciTech Connect

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

Thomas, R.H.

1984-03-01

97

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

98

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

99

The Geostationary Remote Infrared Pollution Sounder (GRIPS): measurement of the carbon gases from space  

NASA Astrophysics Data System (ADS)

Climate change and air quality are the most pressing environmental issues of the 21st century. Despite decades of research, the sources and sinks of key greenhouse gases remain highly uncertain [IPCC1] making quantitative predictions of atmospheric composition and their impacts. The Geostationary Remote Infrared Pollution Sounder (GRIPS) is a multi-purpose instrument designed to reduce uncertainty associated with atmospheric radiative forcing. GRIPS will measure will measure greenhouse gases and aerosols - two of the most important elements in the earth's radiation budget. GRIPS will observe carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), - the carbon gases, nitrous oxide (N2O), water vapor and aerosols with unprecedented precision through the atmosphere. The GRIPS instrument uses gas filter correlation radiometry (GFCR) to detect reflected and thermal IR radiation to detect the gases and the reflected solar radiation in the visible and short-wave infrared bands for aerosols. GRIPS is designed to have sensitivity down to the Earth's surface at ~2-8km nadir resolution. GRIPS can resolve CO2, CO, and CH4 anomalies in the planetary boundary layer and the free troposphere to quantify lofting, diurnal variations and longrange transport. With repeated measurements throughout the day GRIPS can maximize the number of cloud free measurements determining biogenic and anthropogenic sources, sinks, and fluxes. GRIPS is highly complementary to the Orbiting Carbon Observatory, OCO-2, the geostationary Tropospheric Emissions: Monitoring of Pollution (TEMPO) and Advanced Baseline Imager (ABI) and other existing and planned missions.

Schoeberl, M.; Dickerson, R.; Marshall, B. T.; McHugh, M.; Fish, C.; Bloom, H.

2013-09-01

100

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

101

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

102

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

103

Radiation Detection  

NASA Astrophysics Data System (ADS)

Most radiation related to nuclear properties is outside the visible part of the electromagnetic spectrum or involves submicroscopic particles, hence is invisible. Detectors - devices to sense the radiation, and perhaps measure its properties - are essential. The emphasis in research has moved from the characterization of radioactivity, through simple nuclear reactions, to explorations of the extremes of nuclear matter, but the central importance of suitable radiation detectors has persisted. This chapter emphasizes detectors associated with measurements of radioactivity, as opposed to nuclear reactions. Thus, much of the current creative work is excluded, but otherwise the scope of these volumes would at least double. Detectors are classified broadly as based on ionization of gases, conduction in semiconductors, or scintillation. The concluding section is an introduction to systems based on two or more components of one of these basic types.

Griffin, H. C.

104

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

E-print Network

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

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

2014-01-01

105

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...

106

Biomass - Investigating Gases  

NSDL National Science Digital Library

In this lab activity students generate their own biomass gases by heating wood pellets or wood splints in a test tube. They collect the resulting gases and use the gas to roast a marshmallow. Students also evaluate which biomass fuel is the best by their own criteria or by examining the volume of gas produced by each type of fuel.

Benson, Eric E.; Highfill, Melissa; Development, Us D.

107

Gases in Seawater  

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

108

Volcanic Gases and Their Effects  

MedlinePLUS

Volcanic Gases and Their Effects Magma contains dissolved gases that are released into the atmosphere during eruptions. Gases are also released from magma that either remains below ground (for example, as ...

109

Radiation-induced TNF? cross signaling-dependent nuclear import of NF?B favors metastasis in neuroblastoma.  

PubMed

Ascertaining function-specific orchestration of NF?B in response to radiation may reveal a molecular blue-print that dictates induced relapse and metastasis of the neuroblastoma. We recently demonstrated that sustained activation of NF?B caused by ionizing radiation (IR)-initiated TNF?-NF?B feedback signaling leads to radioresistance and recurrence of neuroblastoma. We investigated whether muting IR-triggered or TNF?-dependent second-signaling feedback-dependent NF?B nuclear import results in limiting IR-altered invasion and metastasis. Neuroblastoma cells were exposed to 2 Gy and incubated for 1 h or 24 h. The cells were then treated with an NF?B-targeting peptide blocker, SN50. Upon confirming the blockade in DNA-binding activity, transcription driven transactivation of NF?B and secretion of soluble TNF?, transcriptional alterations of 93 tumor invasion/metastasis genes were assessed by using QPCR profiling and then were selectively validated at the protein level. Exposure to 2 Gy induced 63, 42 and 71 genes in surviving SH-SY5Y, IMR-32 and SK-N-MC cells, respectively. Blocking post-translational nuclear import of NF?B comprehensively inhibited both initial activation of genes (62/63, 34/42 and 65/71) triggered by IR and also TNF?-mediated second signaling-dependent sustained (59/63, 32/42 and 71/71) activation of tumor invasion and metastasis signaling molecules. Furthermore, alterations in the proteins MMP9, MMP2, PYK-2, SPA-1, Dnmt3b, Ask-1, CTGF, MMP10, MTA-2, NF-2, E-Cadherin, TIMP-2 and ADAMTS1 and the results of our scratch-wound assay validate the role of post-translational NF?B in IR-regulated invasion/metastasis. These data demonstrate that IR-induced second-phase (post-translational) NF?B activation mediates TNF?-dependent second signaling and further implies that IR induced NF?B in cells that survive after treatment regulates tumor invasion/metastasis signaling. PMID:23584794

Aravindan, Sheeja; Natarajan, Mohan; Herman, Terence S; Aravindan, Natarajan

2013-08-01

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; Domain, Teachers'

111

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

112

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

Microsoft Academic Search

A 1-yr 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 has a higher sensitivity to cloud liquid water path variations when compared to cloud drop effective radius variations. The mean, median, and standard deviation of observed cloud liquid water path and cloud drop

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

2003-01-01

113

Spectra of scattered photons in large absorbers and their importance for the values of radiation weighting factor wR.  

PubMed

In its review of the present values of radiation weighting factor w(R) and of possible revisions of this factor, the German Radiation Protection Commission has recommended to maintain the approach of ICRP 60 to base the selection of the w(R) value for a given radiation (e.g. fission neutrons) on observed values of the relative biological effectiveness (RBE) of this radiation 'regardless of whether the reference radiation is X rays or gamma rays'. The physical background of the German recommendation is the buildup of a strong field of energy-degraded Compton scattered photons in the human body if exposed to an external field of high-energy photons, so that the total radiation field inside the body is a mixture comprising low and high photon energies. Therefore, it is appropriate that the selection of the w(R) value of the given radiation is guided by RBE values averaged over X rays and gamma rays as the reference radiations. In support of this rationale, the present paper provides a sample of Monte Carlo calculated scattered photon spectra in large absorbers exposed to high-energy photons. Depth-dependent fractional dose contributions of the scattered photons are tabulated for incident energies from 1 to 10 MeV, and estimates of the influence of their degraded energies on the biological effectiveness of the incoming radiation are presented. Accordingly, we point out that it is appropriate to use, for the purposes of 'risk projection', RBE values averaged over X and gamma reference radiations. PMID:15273346

Harder, D; Petoussi-Henss, N; Regulla, D; Zankl, M; Dietze, G

2004-01-01

114

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

PubMed

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

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

2013-05-01

115

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

116

The Importance of XUV Radiation as a Solution to the P V Mass Loss Rate Discrepancy in O Stars  

NASA Astrophysics Data System (ADS)

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 ?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.; Cassinelli, J. P.

2010-03-01

117

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.

118

Solids, Liquids, and Gases  

NSDL National Science Digital Library

In this project you will research solids, liquids, and gases. By the end of this project you will be able to answer the question: Can you tell what is alike and different between solids, liquids, and gases? Read the song about matter. song with music about matter Record your observations on the organizer provided by the teacher. On the diagram write the word solid in one of the circles. Write liquid in one of the circles and write gas in the last circle. As you collect your information write your information under ...

Sibley, Ms.

2009-10-22

119

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

NASA Astrophysics Data System (ADS)

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 scan provided important information about the importance of charge exchange collisions. The pressure in the helicon increases about a factor of 4 when the helicon is turned on. We make the assumption that electron temperature is constant along the axis of the helicon. Several important observations can be made: 1) The electron density increases with power, 2) Plasma flow is important in determining plasma conditions, 3) Radiation losses are large, and 4) charge exchange processes are important.

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

2001-10-01

120

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

121

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

NASA Astrophysics Data System (ADS)

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

Hofgren, Henrik; Sundén, Bengt

2014-09-01

122

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

123

Integrating stereotactic body radiation therapy in stage II/III non-small cell lung cancer: is local control important?  

PubMed

Local control for advanced non-small cell lung cancer (NSCLC) remains a significant problem with chemoradiation local failure rates in the chest of 30-50%. Despite attempts at dose escalation with conventional radiation therapy techniques, toxicities limit the amount of radiation that can be delivered. For stage I NSCLC, mounting evidence supports the use of hypofractionated radiation therapy (SBRT) to gain high local control rates with acceptable toxicity. For healthy patients with stage II/III NSCLC, the National Comprehensive Cancer Network guidelines suggest surgery is the preferred standard of care for patients with radiation therapy planning suggests that we can improve outcomes in stage III patients, but toxicity remains problematic. It follows that with improvements in imaging and delivery of radiotherapy, dose escalation with SBRT incorporation may improve local control in stage II/III NSCLC for medically inoperable patients. The rationale for dose escalation and some of the considerations for incorporation of SBRT dose escalation in stage III lung cancer are reviewed here. PMID:25155973

McGarry, Ronald C

2014-12-01

124

The importance of radiative heat transfer on superplumes in the lower mantle with the new post-perovskite phase change  

E-print Network

of 2650 km. The phase transition at 670 km is endothermic, while we have examined both exothermic and endothermic possibilities for the new phase transition. Our results show the following situations favorable for the development of superplumes: (1) endothermic phase transition for both constant and radiative thermal

Matyska, Ctirad

125

Do sulfate and nitrate coatings on mineral dust have important effects on radiative properties and climate modeling?  

NASA Astrophysics Data System (ADS)

Coating of mineral dust particles by air pollutants leads to core-mantle particles. These composite aerosols could interact differently with atmospheric radiation than the uncoated dust. In our simplified radiative calculations we assumed that a spherical dust core is covered uniformly by a liquid refractive material, such as sulfate or nitrate. Theoretical calculations of optical properties of such particles show that the single-scattering albedo and the asymmetry parameter of core-mantle aerosols only differ significantly from uncoated dust if coating layers exceed 20% of the radius of the dust core. Global simulations of sulfate/nitrate-coated dust particles show that the thickness of the shell can be expected to range from 0 to 20% of the radius of the dust core. The result of this work is that mineral dust particles can be treated as external mixture within radiative calculations but the coating processes lead to changed loads in sulfate, nitrate, and mineral dust aerosol loads and therefore change their impact on Earth radiation. The combined anthropogenic forcing of dust, nitrate, and sulfate aerosols is -0.1 W/m2; however, excluding heterogeneous interactions leads to a 3 times larger negative forcing.

Bauer, S. E.; Mishchenko, M. I.; Lacis, A. A.; Zhang, S.; Perlwitz, J.; Metzger, S. M.

2007-03-01

126

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

127

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...

128

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

129

Synthetic greenhouse gases to decline if Montreal Protocol amended  

NASA Astrophysics Data System (ADS)

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

Wendel, JoAnna

2014-07-01

130

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,

131

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

Microsoft Academic Search

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

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

2007-01-01

132

Biosignature Gases in H2-dominated Atmospheres on Rocky Exoplanets  

NASA Astrophysics Data System (ADS)

Super-Earth exoplanets are being discovered with increasing frequency and some will be able to retain stable H2-dominated atmospheres. We study biosignature gases on exoplanets with thin H2 atmospheres and habitable surface temperatures, using a model atmosphere with photochemistry and a biomass estimate framework for evaluating the plausibility of a range of biosignature gas candidates. We find that photochemically produced H atoms are the most abundant reactive species in H2 atmospheres. In atmospheres with high CO2 levels, atomic O is the major destructive species for some molecules. In Sun-Earth-like UV radiation environments, H (and in some cases O) will rapidly destroy nearly all biosignature gases of interest. The lower UV fluxes from UV-quiet M stars would produce a lower concentration of H (or O) for the same scenario, enabling some biosignature gases to accumulate. The favorability of low-UV radiation environments to accumulate detectable biosignature gases in an H2 atmosphere is closely analogous to the case of oxidized atmospheres, where photochemically produced OH is the major destructive species. Most potential biosignature gases, such as dimethylsulfide and CH3Cl, are therefore more favorable in low-UV, as compared with solar-like UV, environments. A few promising biosignature gas candidates, including NH3 and N2O, are favorable even in solar-like UV environments, as these gases are destroyed directly by photolysis and not by H (or O). A more subtle finding is that most gases produced by life that are fully hydrogenated forms of an element, such as CH4 and H2S, are not effective signs of life in an H2-rich atmosphere because the dominant atmospheric chemistry will generate such gases abiologically, through photochemistry or geochemistry. Suitable biosignature gases in H2-rich atmospheres for super-Earth exoplanets transiting M stars could potentially be detected in transmission spectra with the James Webb Space Telescope.

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

2013-11-01

133

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.

134

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 processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.3 Combustion and gasification technologies for heat and power . . . . . . . . 2-3 2.4 Waste incineration and waste

Zevenhoven, Ron

135

Residual Gases in Crystal Growth Systems  

NASA Technical Reports Server (NTRS)

Residual gases present in closed ampoules may affect different crystal growth processes. That seems to be particularly true under microgravity conditions where, due to weightlessness of the melt, the gases may lead to detached solidification and/or formation of voids and bubbles, as observed in the past. For that reason a good understanding and control of formation of residual gases is important for an optimum design and meaningful interpretation of crystal growth experiments. Our extensive experimental and theoretical studies of the subject, summarized in this paper, include degassing of silica glass and generation of gases from different source materials. Different materials processing conditions, like outgassing under vacuum, annealing in hydrogen, resublimation, different material preparation procedures, multiple annealings, different processing times, and others were applied and their effect on the amount and composition of gas were analyzed. The experimental results were interpreted based on theoretical calculations on diffusion in silica glass and source materials and thermochemistry of the system. Procedures for a reduction of the amount of gas are also discussed.

Palosz, W.

2003-01-01

136

Shock Waves in Granular Gases  

Microsoft Academic Search

This review is the first attempt to systematize the results on shock waves in granular gases. We present experimental and computational evidences of shock and expansion waves propagating within granular gases. The analysis of model flows with shock and expansion waves shows that even smallest kinetic energy dissipations crucially affects such flows. We discuss the role of these waves for

Alexander Goldshtein; Alexander Alexeev; Michael Shapiro

2003-01-01

137

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

138

Radiators  

SciTech Connect

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

Webster, D. M.

1985-07-30

139

Tunable Diode Laser Absorption Measurements of Nitric Oxide in Combustion Gases  

Microsoft Academic Search

Absorption of tunable, infrared, diode laser radiation has been used to measure nitric oxide (NO) in combustion gases. Measurements were made in the post flame gases of an atmospheric pressure flat flame burner doped with calibrated amounts of NO (100-2500 ppm) in order to simulate a range of combustion and exhaust gas conditions. Laser absorption measurements of NO were compared

P. K. Falcone; R. K. Hanson; C. H. Kfuger

1983-01-01

140

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

141

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

142

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

143

Ozone-depleting substances and the greenhouse gases HFCs, PFCs  

E-print Network

Ozone-depleting substances and the greenhouse gases HFCs, PFCs and SF6 Danish consumption-DEPLETING SUBSTANCES 5 1.2 F-GASES 7 1.2.1 HFCs 10 1.2.2 Sulphur hexafluoride (SF6 ) 10 1.2.3 Per fluorinated OZONE-DEPLETING SUBSTANCES 19 3.1 IMPORTS AND EXPORTS 19 3.1.1 CFCs 19 3.1.2 Tetrachloromethane 19 3

144

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

145

Climate-chemical interactions and effects of changing atmospheric trace gases  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

146

Hydrodynamics of unitary Fermi gases  

NASA Astrophysics Data System (ADS)

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

Young, Ryan E.

147

AirCore, a New Tool for Validating Satellite Retrievals of the Mole Fraction of Greenhouse Gases in the Atmospheric Column  

Microsoft Academic Search

The absorption of radiation by trace gases allows their atmospheric concentrations to be estimated from satellite radiance measurements. In the case of greenhouse gases the quantity to be estimated is their mole fraction in dry air averaged over the entire column or a portion thereof. Such estimates cannot be calibrated because one cannot control the abundance of greenhouse gases in

P. P. Tans; C. Sweeney; A. Karion

2010-01-01

148

Spin Transport in Bose Gases  

NASA Astrophysics Data System (ADS)

In this Thesis, we show that in a rotating two-component Bose mixture, the spin drag between the two different spin species shows a Hall effect. This spin drag Hall effect can be observed experimentally by studying the out-of-phase dipole mode of the mixture. We determine the damping of this mode due to spin drag as a function of temperature. We find that due to Bose stimulation there is a strong enhancement of the damping for temperatures close to the critical temperature for Bose-Einstein condensation. We also show the difference between spin drag in Bose gases, Fermi gases and Bose-Fermi mixtures. Furthermore, we investigate coupled spin and heat transport in Bose gases, and calculate the associated coefficients. Finally, we calculate the power spectrum resulting from spin current fluctuations in a Bose gas.

van Driel, H. J.

2012-12-01

149

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

150

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

151

Isothermal compressors for process gases  

SciTech Connect

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

Wiederuh, E.; Meinhart, D. (FH Giessen-Friedberg, Giessen (Germany))

1992-09-01

152

Laminar flames in premixed gases  

NASA Technical Reports Server (NTRS)

Numerical simulation of laminar flames in premixed gases is addressed. Various efforts to solve the laminar flame problem are briefly described, and basic equations to be modeled in a comprehensive description of laminar flames are discussed along with the physical and chemical processes represented by these equations and the numerical requirements to model them. Two flame methods are discussed in some detail: a numerical model for studying transient phenomena and its 2D counterpart method. The various input parameters needed for the models are addressed, and the use of the models is illustrated in several studies of laminar flames in premixed gases. Flammability limits and multidimensional flame propagation are also examined.

Kailasanath, K.

1991-01-01

153

On flame kernel formation and propagation in premixed gases  

SciTech Connect

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

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

2010-12-15

154

Granular solids, liquids, and gases  

Microsoft Academic Search

Granular materials are ubiquitous in the world around us. They have properties that are different from those commonly associated with either solids, liquids, or gases. In this review the authors select some of the special properties of granular materials and describe recent research developments. {copyright} {ital 1996 The American Physical Society.}

Heinrich M. Jaeger; Sidney R. Nagel; Robert P. Behringer

1996-01-01

155

Permeability of cork to gases.  

PubMed

The permeability of gases through uncompressed cork was investigated. More than 100 samples were assessed from different plank qualities to provide a picture of the permeability distribution. A novel technique based on a mass spectrometer leak detector was used to directly measure the helium flow through the central area of small disks 10 mm in diameter and 2 mm thick. The permeability for nitrogen, oxygen, and other gases was measured by the pressure rise technique. Boiled and nonboiled cork samples from different sections were evaluated. An asymmetric frequency distribution ranging 3 orders of magnitude (roughly from 1 to 1000 ?mol/(cm·atm·day)) for selected samples without macroscopic defects was found, having a peak below 100 ?mol/(cm·atm·day). Correlation was found between density and permeability: higher density samples tend to show lower permeability. However, boiled cork showed a mean lower permeability despite having a lower density. The transport mechanism of gases through cork was also examined. Calculations suggest that gases permeate uncompressed cork mainly through small channels between cells under a molecular flow regime. The diameter of such channels was estimated to be in the range of 100 nm, in agreement with the plasmodesmata size in the cork cell walls. PMID:21434693

Faria, David P; Fonseca, Ana L; Pereira, Helen; Teodoro, Orlando M N D

2011-04-27

156

Spectroscopic Imaging of Effluent Gases.  

National Technical Information Service (NTIS)

This paper investigates the possibilities of imaging effluent gases in atmosphere, using a passive gas-correlation technique in the UV and visible region. The experiments have been focused on SO/sub 2/ but some measurements of NO/sub 2/ have also been car...

P. Ragnarson

1988-01-01

157

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

158

Optical remote sensing system for hydrocarbon gases using infrared fibers  

Microsoft Academic Search

An infrared optical fiber made of As2S3 glass has been applied for remote sensing of hydrocarbon gases. The fiber has enabled a transmission of the radiation at 3.39-?m wavelength, where hydrocarbon molecules have strong absorption bands. Using a 3.39-?m He-Ne laser as a light source, an effective remote sensing system has been established. A detection limit of the gas concentration

M. Saito; M. Takizawa; K. Ikegawa; H. Takami

1988-01-01

159

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

160

Isotopic Analysis and Evolved Gases  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

161

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.

162

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

163

Toxicity of pyrolysis gases from polypropylene  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

164

Annihilation in Gases and Galaxies  

NASA Technical Reports Server (NTRS)

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

Drachman, Richard J. (editor)

1990-01-01

165

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

166

Concentration-response data on toxicity of pyrolysis gases from some natural and synthetic polymers  

NASA Technical Reports Server (NTRS)

Concentration-response data are presented on the toxic effects of the pyrolysis gases from some natural and synthetic polymers, using the toxicity screening test method developed at the University of San Francisco. The pyrolysis gases from wool, red oak, Douglas fir, polycaprolactam, polyether sulfone, polyaryl sulfone, and polyphenylene sulfide appeared to exhibit the concentration-response relationships commonly encountered in toxicology. Carbon monoxide seemed to be an important toxicant in the pyrolysis gases from red oak, Douglas fir, and polycaprolactam, but did not appear to have been the principal toxicant in the pyrolysis gases from polyether sulfone and polyphenylene sulfide.

Hilado, C. J.; Huttlinger, N. V.

1978-01-01

167

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

DOEpatents

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

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

1988-01-01

168

Theory of ultracold atomic Fermi gases  

SciTech Connect

The physics of quantum degenerate atomic Fermi gases in uniform as well as in harmonically trapped configurations is reviewed from a theoretical perspective. Emphasis is given to the effect of interactions that play a crucial role, bringing the gas into a superfluid phase at low temperature. In these dilute systems, interactions are characterized by a single parameter, the s-wave scattering length, whose value can be tuned using an external magnetic field near a broad Feshbach resonance. The BCS limit of ordinary Fermi superfluidity, the Bose-Einstein condensation (BEC) of dimers, and the unitary limit of large scattering length are important regimes exhibited by interacting Fermi gases. In particular, the BEC and the unitary regimes are characterized by a high value of the superfluid critical temperature, on the order of the Fermi temperature. Different physical properties are discussed, including the density profiles and the energy of the ground-state configurations, the momentum distribution, the fraction of condensed pairs, collective oscillations and pair-breaking effects, the expansion of the gas, the main thermodynamic properties, the behavior in the presence of optical lattices, and the signatures of superfluidity, such as the existence of quantized vortices, the quenching of the moment of inertia, and the consequences of spin polarization. Various theoretical approaches are considered, ranging from the mean-field description of the BCS-BEC crossover to nonperturbative methods based on quantum Monte Carlo techniques. A major goal of the review is to compare theoretical predictions with available experimental results.

Giorgini, Stefano; Pitaevskii, Lev P.; Stringari, Sandro [Dipartimento di Fisica, Universita di Trento and CNR-INFM BEC Center, I-38050 Povo, Trento (Italy); Dipartimento di Fisica, Universita di Trento and CNR-INFM BEC Center, I-38050 Povo, Trento, Italy and Kapitza Institute for Physical Problems, ul. Kosygina 2, 117334 Moscow (Russian Federation); Dipartimento di Fisica, Universita di Trento and CNR-INFM BEC Center, I-38050 Povo, Trento (Italy)

2008-10-15

169

Wavelength stabilization using a frequency comb for differential absorption lidar measurements of atmospheric greenhouse gases  

NASA Astrophysics Data System (ADS)

Many studies recently have investigated the active remote sensing of atmospheric greenhouse gases, such as CO2 and CH4, by means of differential absorption lidar systems. According to them, the accuracy of the laser wavelengths used is one of the most important issues of this technique in terms of conformance to the high measurement sensitivity requirements defined. The most common method to stabilize the wavelength of the lidar transmitter is the use of an absorption cell, filled with the respective trace gas or another gas with appropriate absorption lines. However, the performance of this method is limited. Here, we present the application of a frequency comb. It is a powerful tool for high precision wavelength stabilization purposes providing the knowledge of the absolute wavelength. By this means the online and offline radiations of a DIAL system can be stabilized to any wavelengths needed with highest accuracy and precision.

Amediek, A.; Ehret, G.; Quatrevalet, M.; Fix, A.; Wirth, M.

2009-12-01

170

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

171

SPECIAL ISSUE DEVOTED TO THE 80TH BIRTHDAY OF S.A. AKHMANOV: Self-action of a high-power 10-?m laser radiation in gases: control of the pulse duration and generation of hot electrons  

NASA Astrophysics Data System (ADS)

The propagation of ultrashort 10-?m laser pulses of power exceeding the critical self-focusing power in xenon and air is numerically simulated. It is shown that the pulse duration in certain regimes in xenon can be decreased by 3-4 times simultaneously with the increase in the pulse power by 2-3 times. It is found that the average energy of electrons in a filament upon filamentation of 10-?m laser pulses in air can exceed 200 eV. The features of the third harmonic and terahertz radiation generation upon filamentation are discussed.

Gordienko, Vyacheslav M.; Platonenko, Viktor T.; Sterzhantov, A. F.

2009-07-01

172

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

173

Spark ignition of flowing gases  

NASA Technical Reports Server (NTRS)

Research conducted at the NACA Lewis Laboratory on ignition of flowing gases by means of long-duration discharges is summarized and analyzed. Data showing the effect of a flowing combustible mixture on the physical and electrical characteristics of spark discharges and data showing the effects of variables on the spark energy required for ignition that has been developed to predict the effect of many of the gas-stream and spark variables is described and applied to a limited amount of experimental data.

Swett, Clyde C , Jr

1956-01-01

174

Importance of high radiation doses (72 Gy or greater) in the treatment of Stage T1-T3 adenocarcinoma of the prostate  

Microsoft Academic Search

Objectives. To analyze the effect of total radiation dose on the outcome of patients treated with external beam radiotherapy for early-stage prostate cancer.Methods. The records of a total of 738 patients with localized prostate cancer treated with external beam radiotherapy (RT) and no androgen deprivation at our institution between July 1986 and February 1999 were reviewed. Two risk groups were

Janice A Lyons; Patrick A Kupelian; Dasarahally S Mohan; Chandana A Reddy; Eric A Klein

2000-01-01

175

Filter for cleaning hot gases  

SciTech Connect

In an apparatus for cleaning hot gases a filter housing has an inlet for unfiltered gas and an outlet for filtered gas. A plurality of filtered inserts are placed within the housing in a manner capable of filtering undesirable components from the gas feed stream. Each filter insert is made of a fibrous filter material. Silicic-acid glass fibers have a silicic acid content of at least 90%. Coated upon the fibers and absorbed into their pores is a metal oxide of aluminum, titanium, zirconium, cromium, nickle or cobalt. A honeycombed cage filled with high temperature resistant perlite is located within the housing between the gas inlet and the fiber inserts. The cage has an inlet and outlet external to the housing for replacing the perlite. A combustion chamber mounted in the housing has a discharge nozzle located so that the nozzle is directed at the filter inserts. Combusting materials in the chamber causes an explosive backflow of gases through the filter inserts.

Gresch, H.; Holter, H.; Hubner, K.; Igelbuscher, H.; Weber, E.

1981-10-20

176

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

177

Effective dynamics of strongly dissipative Rydberg gases  

E-print Network

We investigate the evolution of interacting Rydberg gases in the limit of strong noise and dissipation. Starting from a description in terms of a Markovian quantum master equation we derive effective equations of motion that govern the dynamics on a "coarse-grained" timescale where fast dissipative degrees of freedom have been adiabatically eliminated. Specifically, we consider two scenarios which are of relevance for current theoretical and experimental studies --- Rydberg atoms in a two-level (spin) approximation subject to strong dephasing noise as well as Rydberg atoms under so-called electromagnetically induced transparency (EIT) conditions and fast radiative decay. In the former case we find that the effective dynamics is described by classical rate equations up to second order in an appropriate perturbative expansion. This drastically reduces the computational complexity of numerical simulations in comparison to the full quantum master equation. When accounting for the fourth order correction in this expansion, however, we find that the resulting equation breaks the preservation of positivity and thus cannot be interpreted as a proper classical master rate equation. In the EIT system we find that the expansion up to second order retains information not only on the "classical" observables, but also on some quantum coherences. Nevertheless, this perturbative treatment still achieves a non-trivial reduction of complexity with respect to the original problem.

M Marcuzzi; J Schick; B Olmos; I Lesanovsky

2014-09-29

178

Synchrotron radiation - Applications in the earth sciences  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

179

Particle entanglement in rotating gases  

SciTech Connect

In this paper, we investigate the particle entanglement in two-dimensional (2D) weakly interacting rotating Bose and Fermi gases. We find that both particle localization and vortex localization can be indicated by particle entanglement. We also use particle entanglement to show the occurrence of edge reconstruction of rotating fermions. The different properties of condensate phase and vortex liquid phase of bosons can be reflected by particle entanglement and in vortex liquid phase we construct the same trial wave function with that in [Phys. Rev. Lett. 87, 120405 (2001)] from the viewpoint of entanglement to relate the ground state with quantum Hall state. Finally, the relation between particle entanglement and interaction strength is studied.

Liu Zhao; Fan Heng [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2010-06-15

180

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.

181

Instability in shocked granular gases  

NASA Astrophysics Data System (ADS)

Shocks in granular media, such as vertically oscillated beds, have been shown to develop instabilities. Similar jet formation has been observed in explosively dispersed granular media. Our previous work addressed this instability by performing discrete-particle simulations of inelastic media undergoing shock compression. By allowing finite dissipation within the shock wave, instability manifests itself as distinctive high density non-uniformities and convective rolls within the shock structure. In the present study we have extended this work to investigate this instability at the continuum level. We modeled the Euler equations for granular gases with a modified cooling rate to include an impact velocity threshold necessary for inelastic collisions. Our results showed a fair agreement between the continuum and discrete-particle models. Discrepancies, such as higher frequency instabilities in our continuum results may be attributed to the absence of higher order effects.

Sirmas, Nick; Falle, Sam; Radulescu, Matei

2014-05-01

182

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

183

Continuous Processing with Mars Gases  

NASA Astrophysics Data System (ADS)

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

2001-01-01

184

BOOK REVIEW: Kinetic Theory of Granular Gases  

NASA Astrophysics Data System (ADS)

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

Trizac, Emmanuel

2005-11-01

185

Optical remote sensing system for hydrocarbon gases using infrared fibers  

NASA Astrophysics Data System (ADS)

An infrared optical fiber made of As2S3 glass has been applied for remote sensing of hydrocarbon gases. The fiber has enabled a transmission of the radiation at 3.39-?m wavelength, where hydrocarbon molecules have strong absorption bands. Using a 3.39-?m He-Ne laser as a light source, an effective remote sensing system has been established. A detection limit of the gas concentration is ˜300 ppm for CH4 gas, which is ˜0.6% of the lower explosion limit. The system is also expected as a pressure monitor since it is highly sensitive to the gas pressure.

Saito, M.; Takizawa, M.; Ikegawa, K.; Takami, H.

1988-01-01

186

Measurement techniques for analysis of fission fragment excited gases  

NASA Technical Reports Server (NTRS)

Spectroscopic analysis of fission fragment excited He, Ar, Xe, N2, Ne, Ar-N2, and Ne-N2 have been conducted. Boltzmann plot analysis of He, Ar and Xe have indicated a nonequilibrium, recombining plasma, and population inversions have been found in these gases. The observed radiating species in helium have been adequately described by a simple kinetic model. A more extensive model for argon, nitrogen and Ar-N2 mixtures was developed which adequately describes the energy flow in the system and compares favorably with experimental measurements. The kinetic processes involved in these systems are discussed.

Schneider, R. T.; Carroll, E. E.; Davis, J. F.; Davie, R. N.; Maguire, T. C.; Shipman, R. G.

1976-01-01

187

Toxicity of pyrolysis gases from polyoxymethylene  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

188

40 CFR 86.1514 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

189

Analyzing Gases From Decomposing Electrical Insulation  

NASA Technical Reports Server (NTRS)

Test fixture holds insulated wire and traps gases emitted by heating of wire. Used with gas chromatograph and/or mass spectrometer, to analyze gases emitted by insulation on wire when wire heated with controlled current in controlled atmosphere to simulate pyrolysis, combustion, and arc tracking. Small, inexpensive, easily maintained, and relatively nonreactive to organic compounds produced during breakdown of insulation.

Moffett, Gary; Shelley, Timothy J.; Morelli, John J.

1995-01-01

190

40 CFR 92.112 - Analytical gases.  

Code of Federal Regulations, 2012 CFR

...the diluent. (c) Gases for the methane analyzer...the diluent. (d) Gases for the NOX analyzer...blend of 40±2 percent hydrogen with the balance being...response; 98 to 100 percent hydrogen fuel may be used with...The allowable zero gas (air or...

2012-07-01

191

40 CFR 92.112 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...the diluent. (c) Gases for the methane analyzer...the diluent. (d) Gases for the NOX analyzer...blend of 40±2 percent hydrogen with the balance being...response; 98 to 100 percent hydrogen fuel may be used with...The allowable zero gas (air or...

2013-07-01

192

40 CFR 92.112 - Analytical gases.  

Code of Federal Regulations, 2011 CFR

...the diluent. (c) Gases for the methane analyzer...the diluent. (d) Gases for the NOX analyzer...blend of 40±2 percent hydrogen with the balance being...response; 98 to 100 percent hydrogen fuel may be used with...The allowable zero gas (air or...

2011-07-01

193

Facilitating Conceptual Change in Gases Concepts  

NASA Astrophysics Data System (ADS)

The aim of this study is to investigate the effectiveness of conceptual change oriented instruction (CCOI) over traditionally designed chemistry instruction (TDCI) on overcoming 10th grade students' misconceptions on gases concepts. In addition, the effect of gender difference on students' understanding of gases concepts was investigated. The subjects of this study consisted of 74 10th grade students from two chemistry classes. One of the classes was assigned as experimental group and the other group was assigned as control group. The experimental group was instructed with CCOI and the control group was instructed by TDCI. Gases Concept Test (GCT) was administered to both groups as pre- and post-tests to measure the students' conceptual understanding. The results showed that students in the experimental group got higher average scores from Gases Concept Test. Also, a significant difference was found between the performance of females and that of males in terms of understanding gases concepts in favor of males.

Çetin, Pinar Seda; Kaya, Ebru; Geban, Ömer

2009-04-01

194

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

195

The state of greenhouse gases in the atmosphere using global observations through 2010  

NASA Astrophysics Data System (ADS)

The Global Atmosphere Watch (GAW) Programme of the World Meteorological Organization (WMO) provides a framework for observing and assessing the state and development of environmental issues related to 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 16th meeting was held in Wellington, New Zealand, on 25 - 28 October 2011 (http://www.niwa.co.nz/our-science/atmosphere/ggmt-2011). Surface observations are made at more than 100 stations worldwide for CO2 and CH4 and at a smaller number of stations for many other greenhouse gases. Results of the latest global analysis were published in the WMO/GAW Greenhouse Gas Bulletin in November 2011. It highlights the importance of N2O, the third most important long-lived greenhouse gas in the atmosphere. Globally averaged dry-air mole fractions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) reached new highs in 2010, with CO2 at 389.0 ppm, CH4 at 1808 ppb and N2O at 323.2 ppb. These values are greater than those in pre-industrial times (before 1750) by 39%, 158% and 20%, respectively. An increase of the annual mean CO2 mole fraction from 2009 to 2010 amounted to 2.3 ppm, which is higher than the average growth rate for the 1990s (~ 1.5 ppm/yr) and the one for the past decade (~ 2.0 ppm/yr). The growth rate of CH4 decreased from ~ 13 ppb/yr during the early 1980s to near zero from 1999 to 2006. Since 2007, atmospheric CH4 has been increasing again. The 19 ppb rise from 2006 to 2009 was followed by a 5 ppb rise in 2010. The growth rate of N2O in 2010 was 0.8 ppb/yr which is comparable to the average over the last 10 years (0.75 ppb/yr). The NOAA Annual Greenhouse Gas Index (AGGI) shows that from 1990 to 2010, radiative forcing from nearly all long-lived greenhouse gases increased by 29% and reached 2.81W/m2, with CO2 accounting for nearly 80% of this increase. This radiative forcing corresponds to a CO2-eq mole fraction of 469.7 ppm, which falls in the middle of the IPCC AR4 category I scenario with CO2-eq in the range 445-490 ppm (corresponding to the projected global average temperature rise above pre-industrial level at equilibrium in the range of 2-2.4 degree C). The radiative forcing of N2O now exceeds that of CFC-12.

Tarasova, O. A.; Koide, H.; Dlugokencky, E.; Hall, B.; Montzka, S. A.; Krummel, P.; Brunke, E.; Scheel, H.-E.

2012-04-01

196

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

197

A study on the importance of dependent radiative effects in determining the spectral and total emittance of particulate ash deposits in pulverised fuel fired furnaces  

Microsoft Academic Search

This paper presents the results of an experimental and theoretical investigation on the importance of dependent effects in determining the emittance of ash deposits. A model has been developed to predict the spectral emittance (directional, normal, hemispherical) of semi-transparent and opaque particulate deposits without considering dependent effects. Predictions from this model have been presented to illustrate the effects of particle

S. P Bhattacharya; T. F Wall; M Arduini-Schuster

1997-01-01

198

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

USGS Publications Warehouse

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

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

2009-01-01

199

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

200

Impact degassing of water and noble gases from silicates  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

201

Impact degassing of water and noble gases from silicates  

NASA Astrophysics Data System (ADS)

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

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

202

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

NASA Astrophysics Data System (ADS)

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.

1990-08-01

203

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

204

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

E-print Network

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

Yu-Qing Lou; Chen Zheng

2003-07-14

205

Climate-chemical interactions and effects of changing atmospheric trace gases  

Microsoft Academic Search

The paper considers trace gas-climate effects including the greenhouse effect of polyatomic trace gases, the nature of the radiative-chemical interactions, and radiative-dynamical interactions in the stratosphere, and the role of these effects in governing stratospheric climate change. Special consideration is given to recent developments in the investigations of the role of oceans in governing the transient climate responses, and a

V. Ramanathan; L. Callis; R. Cess; J. Hansen; I. Isaksen; W. Kuhn; A. Lacis; F. Luther; J. Mahlman; R. Reck

1987-01-01

206

Noble gases in meteorites and terrestrial planets  

NASA Technical Reports Server (NTRS)

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

Wacker, J. F.

1985-01-01

207

40 CFR 86.1214-85 - Analytical gases.  

...Heavy-Duty Vehicles § 86.1214-85 Analytical gases. (a) Analyzer gases. (1) Gases for the hydrocarbon analyzer shall be: ...vehicles) shall be a blend of 40 ±2 percent hydrogen with the balance being helium. The...

2014-07-01

208

40 CFR 86.1214-85 - Analytical gases.  

Code of Federal Regulations, 2011 CFR

...Heavy-Duty Vehicles § 86.1214-85 Analytical gases. (a) Analyzer gases. (1) Gases for the hydrocarbon analyzer shall be: ...vehicles) shall be a blend of 40 ±2 percent hydrogen with the balance being helium. The...

2011-07-01

209

40 CFR 86.1214-85 - Analytical gases.  

Code of Federal Regulations, 2012 CFR

...Heavy-Duty Vehicles § 86.1214-85 Analytical gases. (a) Analyzer gases. (1) Gases for the hydrocarbon analyzer shall be: ...vehicles) shall be a blend of 40 ±2 percent hydrogen with the balance being helium. The...

2012-07-01

210

40 CFR 86.1214-85 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...Heavy-Duty Vehicles § 86.1214-85 Analytical gases. (a) Analyzer gases. (1) Gases for the hydrocarbon analyzer shall be: ...vehicles) shall be a blend of 40 ±2 percent hydrogen with the balance being helium. The...

2013-07-01

211

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.

212

An approach for retrieval of atmospheric trace gases CO2, CH4 and CO from the future Canadian micro earth observation satellite (MEOS)  

Microsoft Academic Search

Among all trace gases, the carbon dioxide and methane provide the largest contribution to the climate radiative forcing and together with carbon monoxide also to the global atmospheric carbon budget. New Micro Earth Observation Satellite (MEOS) mission is proposed to obtain information about these gases along with some other mission's objectives related to studying cloud and aerosol interactions. The miniature

Alexander P. Trishchenko; Konstantin V. Khlopenkov; Shusen Wang; Yi Luo; Roman V. Kruzelecky; Wes Jamroz; Guennadi Kroupnik

2007-01-01

213

Megacity Radiative Forcing: A Mexico City Case Study  

NASA Astrophysics Data System (ADS)

We assess the radiative forcing budget of the largest megacity in North America, Mexico City. While particular aspects of the regional environmental impacts of cities on their surroundings have been thoroughly investigated, e.g., air quality and acid rain, relatively little effort has been focused on the net radiative impact of a megacity on global climate. The range of radiative impacts from a megacity covers many spatial and temporal scales from short-term regional-scale effects due to aerosols and relatively short-lived gases (O3) to long-term global-scale impacts due to long-lived trace gases (e.g., CH4, CO2). In this study we use both bottom-up and top-down approaches to evaluate these radiative forcings. From the bottom up we utilize emission inventories and the Model for Ozone And Related Chemical Tracers (MOZART-2) chemistry-aerosol model. From the top down we use observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument, the Aerosol Robotic Network (AERONET), and in situ aerosol single scattering albedo measurements collected during the Megacity Initiative-Local and Global Research Observations (MILAGRO) campaign. We also explore the radiative impact of various emission control strategies that focus on improving urban air quality. We show that the warming by greenhouse gases like CO2 and ozone can be moderated or exacerbated by aerosols depending on their optical properties. As the size and number of megacities increase and clean air regulations are implemented, metrics such as the net radiative forcing may become increasingly important in comparing the impact of urban centers and assessing pollution abatement policies.

Olsen, S. C.; Dubey, M. K.; Chylek, P.; Mazzoleni, C.; Zhang, Y.; Randerson, J. T.; Horowitz, L.

2006-12-01

214

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

SciTech Connect

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

Spratt, Daniel E.; Zumsteg, Zach; Ghadjar, Pirus; Pangasa, Misha; Pei, Xin [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)] [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Fine, Samson W. [Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)] [Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Yamada, Yoshiya; Kollmeier, Marisa [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)] [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Zelefsky, Michael J., E-mail: zelefskm@mskcc.org [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

2013-04-01

215

Spectroscopy and Photoreactivity of Atmospheric Trace Gases.  

NASA Astrophysics Data System (ADS)

This thesis explores in detail some aspects of light absorption and light initiated chemical reactions in the atmosphere. The specific themes involved in this work include: laboratory spectroscopic measurements of atmospheric trace gases; fundamental studies of chemical reaction dynamics and the influence of weakly-bound complexes on reactivity; and the atmospheric relevance of the photoreactions of complexes. Laboratory studies of ultraviolet-visible (UV -VIS) absorption cross sections are necessary for the interpretation of measurements made in the field. The development and application of a new methodology for measuring high resolution UV-VIS absorption cross sections of molecules and radicals at atmospheric conditions are described. The instrument is based on a commercial Fourier transform spectrometer used in conjunction with a supersonic jet expansion for sample preparation. Infrared spectra are used to characterize sample conditions such as the temperature and the abundance of interferences. High resolution UV-VIS cross sections of two important atmospheric trace gases, nitrogen dioxide and chlorine dioxide, were measured at 200 +/- 20 K, which is characteristic of temperatures in the lower stratosphere. The second part of the thesis focuses on light initiated reactions of molecular complexes. Calculations of the atmospheric rate of photolysis of the ozone-water complex, O_3cdotH _2O, and its potential role as a source of OH in the troposphere are discussed. This work represents a new perspective on the role of weakly bound complexes in the atmosphere, because it proposes direct atmospheric photodissociation of such species. The calculations show that O_3cdotH_2 O photolysis is a potentially significant tropospheric OH source. Studies of the reactions of O(^1 D) with methane and propane monomers and clusters are also presented. Crossed molecular beams were used to prepare the reactants, and laser induced fluorescence was applied to the detection of the OH product. Energy distributions in different OH product degrees of freedom, including translation, vibration, and rotation, are reported. From this data, the mechanisms for the reactions of O( ^1D) with methane, propane and their clusters are established.

Frost, Gregory John

1995-01-01

216

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-DEPLETING SUBSTANCES 5 1.2 F-GASES 7 1.2.1 HFCs 10 1.2.2 Sulphur hexafluoride (SF6 ) 10 1.2.3 Per fluorinated OZONE-DEPLETING SUBSTANCES 18 3.1 IMPORTS AND EXPORTS 18 3.1.1 CFCs 18 3.1.2 Tetrachloromethane 19 3

217

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 26, NO. 4, 2009, 748762 Climate Responses to Direct Radiative Forcing of Anthropogenic  

E-print Network

Radiative Forcing of Anthropogenic Aerosols, Tropospheric Ozone, and Long-Lived Greenhouse Gases in Eastern of regional climate change in China. Key words: direct effect of aerosol, tropospheric ozone, greenhouse gases radiative forcing of anthropogenic aerosols, tropospheric ozone, and long-lived greenhouse gases in eastern

218

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

219

Remote monitoring of volcanic gases using passive Fourier transform spectroscopy  

SciTech Connect

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

Love, S.P.; Goff, F.; Counce, D.; Schmidt, S.C. [Los Alamos National Lab., NM (United States); Siebe, C.; Delgado, H. [Univ. Nactional Autonoma de Mexico, Coyoacan (Mexico)

1999-06-01

220

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

221

Quantum gases: The high-symmetry switch  

NASA Astrophysics Data System (ADS)

Accessing orbital exchange between highly symmetric many-component spins may hold the key to a number of exotic, strongly correlated quantum phenomena, but probing such exchange is far from easy. An experiment with ultracold gases takes on the task.

Gorshkov, Alexey V.

2014-10-01

222

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

223

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

224

Flow of real gases through porous media  

E-print Network

FLOW OF REAL GASES THROUGH POROUS MEDIA A Thesis By RAFI AL-HUSSAINY Submitted to the Graduate College of the Texas ASSAM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major Subject: PETROLEUM... ENGINEERING January 1965 FLOW OF REAL GASES THROUGH POROUS MEDIA A Thesis By RAFI AL-HUSSAINY Approved as to style and content by: (Chairm ommittee) (Head of Department) (Member) (Member) January 1965 497681 TABLE OF CONTENTS ABSTRAC T Page...

Al-Hussainy, Rafi

2012-06-07

225

Global warming potential, global warming commitment and other indexes as characteristics of the effects of greenhouse gases on Earth’s climate  

Microsoft Academic Search

Radiative forcing (RF) is widely used for evaluation of separate radiative active substance effects on climate. For photochemically active greenhouse gases, this effect detachment for the definite radiative active substance content change poses the problem of filtering out of all other chemically connected greenhouse gas effects. Two schemes of RF calculation for such greenhouse gas are proposed and analyzed: the

Victor A Frolkis; Igor L Karol; Andrey A Kiselev

2002-01-01

226

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...

227

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

228

Dedicated monitoring of anesthetic and respiratory gases by Raman scattering.  

PubMed

The monitoring of respiratory and anesthetic gases in the operating room is important for patient safety. This study measured the accuracy and response time of a multiple-gas monitoring instrument that uses Raman light scattering. Measurements of oxygen, carbon dioxide, nitrogen, nitrous oxide, halothane, enflurane, and isoflurane concentrations were compared with a gas mixer standard and with measurements made with an infrared anesthetic agent analyzer. Correlation coefficients were all greater than 0.999, and probable errors were less than 0.43 vol% for the gases and less than 0.03 vol% for the volatile anesthetics. Response time was 67 ms with a sample flow rate of 150 ml/min. There was some signal overlap between nitrogen and nitrous oxide and between the volatile anesthetic agents. Such overlap can be compensated for by linear matrix analysis. The Raman instrument promises a monitoring capability equivalent to the mass spectrometer and should prove attractive for the monitoring of respiratory and anesthetic gases in the operating room. PMID:3097268

VanWagenen, R A; Westenskow, D R; Benner, R E; Gregonis, D E; Coleman, D L

1986-10-01

229

Photoextraction of molecular gases from an organic polymer film  

NASA Astrophysics Data System (ADS)

Photoextraction of various molecular gases from a polydimethylsiloxane (PDMS) polymer film has been studied. Change in the density of molecular gases has been measured as a function of the illumination duration, intensity and wavelength of light, and temperature of the coating. A linear dependence of the rate of photoextraction on the intensity of the incident light has been established. Similar to the photoelectric effect, photoextraction is absent in the long-wavelength spectral range down to 550 nm. The effect increases sharply in the short-wavelength spectral range below a threshold of about 550 nm. Photoextraction is absent at temperatures below the glass-transition temperature of PDMS (-125°C), at which, as is known, the bulk diffusion of molecular gases in the film is strongly suppressed. At long-term irradiation of the film, the number of photoextracted molecules decreases exponentially with time. This increase is accompanied by a long tail of a diffusion form. The results indicate that photoextraction has a nonthermal nature and demonstrate the important role of bulk diffusion in the process of light-induced extraction of molecules from the surface.

Atutov, S. N.; Danilina, N. A.; Plekhanov, A. I.; Poteshkina, K. D.

2014-08-01

230

Radiation Protection  

NASA Astrophysics Data System (ADS)

Radiation protection is a very important aspect for the application of particle detectors in many different fields, like high energy physics, medicine, materials science, oil and mineral exploration, and arts, to name a few. The knowledge of radiation units, the experience with shielding, and information on biological effects of radiation are vital for scientists handling radioactive sources or operating accelerators or X-ray equipment. This article describes the modern radiation units and their conversions to older units which are still in use in many countries. Typical radiation sources and detectors used in the field of radiation protection are presented. The legal regulations in nearly all countries follow closely the recommendations of the International Commission on Radiological Protection (ICRP). Tables and diagrams with relevant information on the handling of radiation sources provide useful data for the researcher working in this field.

Grupen, Claus

231

Responses of trace gases to hydrologic pulses in desert floodplains  

NASA Astrophysics Data System (ADS)

Pulsed hydrologic inputs interact with antecedent moisture conditions to shape biogeochemical dynamics in many ecosystems, but the outcomes of these interactions remain difficult to predict. Hydrologic pulses may influence biogeochemical activity through several mechanisms: by providing water as a resource, providing limiting nutrients or substrates that fuel particular biogeochemical pathways, or determining redox conditions. Antecedent moisture conditions may modify the relative importance of each of these potential mechanisms, by influencing accumulation of labile carbon and nutrients, the severity of water limitation to biological processes, and longer-term effects on abiotic conditions, including redox. We experimentally applied hydrologic pulses of different sizes (1-cm and 20-cm events) to soils of desert floodplains and assessed responses of trace gases (CO2, CH4, NO, and N2O) in dry and monsoon seasons to test these mechanisms. Size of the hydrologic pulse strongly interacted with antecedent soil-moisture conditions to determine emissions of some trace gases. Following dry antecedent conditions, water addition stimulated emissions of CO2, CH4, and NO, but not N2O, and larger experimental pulses resulted in larger fluxes. In the monsoon season, responses to water addition were muted and size of the hydrologic pulse had no effect, except for CH4emission, which increased in response to the 20-cm event. Seasonal contrasts indicated that antecedent moisture conditions constrain the effects of hydrologic pulses on biogeochemical processes, whereas contrasts among responses of different trace gases demonstrated that mechanisms controlling emissions of particular gases are water limitation (CO2), in situ production of nitrogen substrates (NO), or redox conditions (CH4). Strong and predictable interactive effects of water inputs and antecedent conditions indicate that extended droughts may cause elevated emissions of gaseous C and NO following the return of precipitation, whereas larger floods or longer wet seasons are expected to dampen gaseous fluxes, which may contribute to conserving soil C and nutrients within floodplains.

Harms, Tamara K.; Grimm, Nancy B.

2012-03-01

232

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

233

Broader perspectives for comparing different greenhouse gases.  

PubMed

Over the last 20 years, different greenhouse gases have been compared, in the context of climate change, primarily through the concept of global warming potentials (GWPs). This considers the climate forcing caused by pulse emissions and integrated over a fixed time horizon. Recent studies have shown that uncertainties in GWP values are significantly larger than previously thought and, while past literature in this area has raised alternative means of comparison, there is not yet any clear alternative. We propose that a broader framework for comparing greenhouse gases has become necessary and that this cannot be addressed by using simple fixed exchange rates. From a policy perspective, the framework needs to be clearly aligned with the goal of climate stabilization, and we show that comparisons between gases can be better addressed in this context by the forcing equivalence index (FEI). From a science perspective, a framework for comparing greenhouse gases should also consider the full range of processes that affect atmospheric composition and how these may alter for climate stabilization at different levels. We cover a basis for a broader approach to comparing greenhouse gases by summarizing the uncertainties in GWPs, linking those to uncertainties in the FEIs consistent with stabilization, and then to a framework for addressing uncertainties in the corresponding biogeochemical processes. PMID:21502165

Manning, Martin; Reisinger, Andy

2011-05-28

234

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

SciTech Connect

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

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

2013-11-10

235

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.

236

Bromine-containing source gases during EASOE  

SciTech Connect

The authors report three different vertical profile measurements of three bromine containing gases which are thought to be the major sources of active bromine in the stratosphere. These gases are CBrClF[sub 2] (Halon-1211), CBrF[sub 3] (Halon-1301) and methyl bromide (CH[sub 3]Br). They were sampled using cryogenic samplers from balloon borne flights from Kiruna during January, February and March 1992. The two halons are of anthropogenic origin, while methyl bromide is thought to have a relatively large natural origin. Consistent with the decrease in concentration of these gases with altitude was an increase in the density of BrO[sub x] with altitude.

Fabian, P. (Univ. of Munich (Germany)); Borchers, R.; Kourtidis, K. (Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau (Germany))

1994-06-22

237

Rare gases in cyclosilicates and cogenetic minerals  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

238

The Flow of Gases in Narrow Channels  

NASA Technical Reports Server (NTRS)

Measurements were made of the flow of gases through various narrow channels a few microns wide at average pressures from 0.00003 to 40 cm. Hg. The flow rate, defined as the product of pressure and volume rate of flow at unit pressure difference, first decreased linearly with decrease in mean pressure in the channel, in agreement with laminar-flow theory, reached a minimum when the mean path length was approximately equal to the channel width, and then increased to a constant value. The product of flow rate and square root of molecular number was approximately the same function of mean path length for all gases for a given channel.

Rasmussen, R E H

1951-01-01

239

Comparison of driving gases for IABPs.  

PubMed

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

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

1981-01-01

240

Stationary light in cold-atomic gases  

SciTech Connect

We discuss stationary light created by a pair of counterpropagating 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 nonexponential and can be faster or slower than in hot gases.

Nikoghosyan, Gor [Fachbereich Physik and Research Center OPTIMAS, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Institute of Physical Research, 378410 Ashtarak-2 (Armenia); Fleischhauer, Michael [Fachbereich Physik and Research Center OPTIMAS, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany)

2009-07-15

241

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

E-print Network

concentrations of the combustion products water (H2O) and carbon dioxide (CO2). More concern, however, goes should be included in the list of species not be emitted into the atmosphere carelessly. CO2 atmosphere at ground-level. The formation of ground-level ozone from traffic exhaust gases during sunny

Zevenhoven, Ron

242

PREFACE: The 27th International Conference on Phenomena in Ionized Gases (ICPIG)  

NASA Astrophysics Data System (ADS)

The 27th International Conference on Phenomena in Ionized Gases (ICPIG) was held in the conference resort of NH Koningshof in Veldhoven, near Eindhoven, The Netherlands, 17-22 July 2005. ICPIG is an important biennial event at which academics and industrialists working in low-temperature plasma science can meet. The 27th ICPIG was organized under the sponsorship of the International Union of Pure and Applied Chemistry (IUPAP), the Royal Dutch Academy of Sciences (KNAW), the Research School Centre for Plasma Physics and Radiation Technology (CPS), the Dutch Organization for Fundamental Research on Matter (FOM), Stichting Physica, the Dutch organization for Scientific Research (NWO), Philips Lighting, and the Eindhoven University of Technology. The scientific scope of this joint conference focused on both experimental and theoretical aspects of the physics of ionized gases as well as on industrial applications. It covered the following topics: • Kinetics, thermodynamics and transport phenomena • Elementary processes • Low-pressure glows • Coronas, sparks, surface discharges and high-pressure glows • Arc discharges • High-frequency discharges • Ionospheric, magnetospheric and astrophysical plasmas • Plasma diagnostic methods • Plasma wall interaction, electrode and surface effects • Physical aspects of plasma chemistry, plasma processing of surfaces and thin film technology • The generation and dynamics of plasma flows • Non-ideal plasmas, clusters and dusty plasmas • Waves and instabilities, including shock waves • Nonlinear phenomena, self-organization and chaos • Particle and laser beam interaction with plasmas • Plasma sources of radiation • Numerical modelling • Plasmas for environmental issues • Highly ionized, low-pressure plasmas (plasma thrusters, ion sources and surface treatment) • High-pressure, non-thermal plasmas. ICPIG was attended by close to 400 scientists from 41 countries. A selection of the invited papers is published in this special issue. The 401 contributed papers were presented in five poster sessions. The abstracts of all the oral and poster contributions were published in the CD of the conference proceedings. I would like to thank all members of the Local Organizing Committee as well as the members of the International Scientific Committee of ICPIG for their indispensable contributions to the success of this joint meeting. We are particularly grateful to the Editor-in-Chief of Plasma Sources Science and Technology, Professor Noah Hershkowitz, for the opportunity to publish the invited papers in this special issue and so bring the 27th ICPIG to a wider audience.

Kroesen, Gerrit

2006-05-01

243

Increased soil emissions of potent greenhouse gases under increased atmospheric CO2  

NASA Astrophysics Data System (ADS)

Increasing concentrations of atmospheric carbon dioxide (CO2) can affect biotic and abiotic conditions in soil, such as microbial activity and water content. In turn, these changes might be expected to alter the production and consumption of the important greenhouse gases nitrous oxide (N2O) and methane (CH4) (refs 2, 3). However, studies on fluxes of N2O and CH4 from soil under increased atmospheric CO2 have not been quantitatively synthesized. Here we show, using meta-analysis, that increased CO2 (ranging from 463 to 780 parts per million by volume) stimulates both N2O emissions from upland soils and CH4 emissions from rice paddies and natural wetlands. Because enhanced greenhouse-gas emissions add to the radiative forcing of terrestrial ecosystems, these emissions are expected to negate at least 16.6 per cent of the climate change mitigation potential previously predicted from an increase in the terrestrial carbon sink under increased atmospheric CO2 concentrations. Our results therefore suggest that the capacity of land ecosystems to slow climate warming has been overestimated.

van Groenigen, Kees Jan; Osenberg, Craig W.; Hungate, Bruce A.

2011-07-01

244

Increased soil emissions of potent greenhouse gases under increased atmospheric CO2.  

PubMed

Increasing concentrations of atmospheric carbon dioxide (CO(2)) can affect biotic and abiotic conditions in soil, such as microbial activity and water content. In turn, these changes might be expected to alter the production and consumption of the important greenhouse gases nitrous oxide (N(2)O) and methane (CH(4)) (refs 2, 3). However, studies on fluxes of N(2)O and CH(4) from soil under increased atmospheric CO(2) have not been quantitatively synthesized. Here we show, using meta-analysis, that increased CO(2) (ranging from 463 to 780 parts per million by volume) stimulates both N(2)O emissions from upland soils and CH(4) emissions from rice paddies and natural wetlands. Because enhanced greenhouse-gas emissions add to the radiative forcing of terrestrial ecosystems, these emissions are expected to negate at least 16.6 per cent of the climate change mitigation potential previously predicted from an increase in the terrestrial carbon sink under increased atmospheric CO(2) concentrations. Our results therefore suggest that the capacity of land ecosystems to slow climate warming has been overestimated. PMID:21753852

van Groenigen, Kees Jan; Osenberg, Craig W; Hungate, Bruce A

2011-07-14

245

Process for purifying gases containing HCN  

Microsoft Academic Search

Gases containing hydrogen cyanide, ammonia and hydrogen sulfide are purified by first washing the gas with a suspension of solid sulfur to fix the hydrogen cyanide as ammonium thiocyanate and ammonium thiosulfate. The resulting suspension is then subjected to a wet-oxidation wherein the thiosulfate and a part of the thiocyanate is converted into sulfuric acid and ammonium sulfate afterwhich the

I. Ooka; N. Tomihisa; Y. Nogami; K. Katagiri

1976-01-01

246

Heat Conductivity of Polyatomic and Polar Gases  

Microsoft Academic Search

The formal kinetic theory of Wang Chang and Uhlenbeck and of Taxman has been used to derive explicit expressions for the heat conductivity of polyatomic and polar gases. By systematic inclusion of terms involving inelastic collisions the usual modified Eucken expression is derived as a first approximation, and as a second approximation an expression involving the relaxation times for various

E. A. Mason; L. Monchick

1962-01-01

247

Are Volcanic Gases Serial Killers? Bruno Scaillet*  

E-print Network

Are Volcanic Gases Serial Killers? Bruno Scaillet* Volatiles released by volcanic eruptions scenarios derived from the study of recent basalt outbursts, such as the 1783-1784 Laki eruption in Iceland magma may well be a lower bound. Some researchers have proposed on the basis of calculations that basalt

Paris-Sud XI, Université de

248

Superfluid regimes in degenerate atomic Fermi gases  

SciTech Connect

We give a brief overview of recent studies of quantum degenerate regimes in ultracold Fermi gases. The attention is focused on the regime of Bose-Einstein condensation of weakly bound molecules of fermionic atoms, formed at a large positive scattering length for the interspecies atom-atom interaction. We analyze remarkable collisional stability of these molecules and draw prospects for future studies.

Shlyapnikov, G.V. [Laboratoire Physique Theorique et Modeles Statistique, Universite Paris Sud, Bat. 100, 91405 Orsay (France); Van der Waals-Zeeman Institute, University of Amsterdam, Valckenierstraat 65/67, 1018 XEAmsterdam (Netherlands)

2005-05-05

249

DECONTAMINATION OF DISSOLVER VENT GASES AT HANFORD  

Microsoft Academic Search

The dissolver vent gases constitute the most highly contaminated gas ; stream in the present Hanford Separations Plants. From the health hazard ; viewpoint there are two principal contaminants, radio-iodine and an aerosol ; composed of other fission products. An extensive study has been made at Hanford ; of methods and equipment to remove effeciively these materials. Tbis ; investigation

A. G. Blasewitz; R. V. Carlisle; B. F. Judson; M. F. Katzer; E. F. Kurtz; W. C. Schmidt; B. Weidenbaum

1951-01-01

250

Toxicity of pyrolysis gases from polyether sulfone  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

251

Toxicity of pyrolysis gases from foam plastics  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

252

Removing Sulphur Dioxide From Stack Gases  

ERIC Educational Resources Information Center

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

Slack, A. V.

1973-01-01

253

Noble Gases in Five Rumuruti Chondrites  

NASA Astrophysics Data System (ADS)

Concentration and isotopic composition have been measured in five new R-chondrites: Dar al Gani 417, Northwest Africa 053, Ouzina, Sahara 98248, and Sahara 99531. Two of these meteorites contain solar trapped gases, NWA 053 has an unusual short exposure age of 0.2 Ma.

Weber, H. W.; Schultz, L.

2001-03-01

254

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

255

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

256

Optical properties of explosive-driven shock waves in noble gases  

SciTech Connect

High explosives have been used to shock-heat rare gases to brightness temperatures up to 36,000/sup 0/K, with large radiating areas. Temperatures were determined from radiometer signals at both 280 and 520 nm. Shock velocities up to 9 mm/..mu..s were used in both plane and cyclindrical geometries. Neon, argon, krypton, and xenon gases at atmospheric initial pressure were examined in plane shocks. Using argon, the effects of increased initial pressure were studied. For cylindrical shock expansion in argon, brightness temperatures were measured over a range of shock velocities from 3 to 9 mm/..mu..s. Up to 4% of the explosive energy was emitted as radiation. The shock waves are found to be reasonable approximations to blackbodies.

Jones, C.R.; Davis, W.C.

1983-01-01

257

Medical intelligence article: assessing the impact on global climate from general anesthetic gases.  

PubMed

Although present in the atmosphere with a combined concentration approximately 100,000 times lower than carbon dioxide (i.e., the principal anthropogenic driver of climate change), halogenated organic compounds are responsible for a warming effect of approximately 10% to 15% of the total anthropogenic radiative forcing of climate, as measured relative to the start of the industrial era (approximately 1750). The family of anesthetic gases includes several halogenated organic compounds that are strong greenhouse gases. In this short report, we provide an overview of the state of knowledge regarding the impact of anesthetic gas release on the environment, with particular focus on its contribution to the radiative forcing of climate change. PMID:22492189

Sulbaek Andersen, Mads P; Nielsen, Ole J; Wallington, Timothy J; Karpichev, Boris; Sander, Stanley P

2012-05-01

258

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

259

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

E-print Network

% Mobile combustion sources ~ 14 % Nitric acid production ~ 5 % HFCs, PFCs, SF66 Substution of ozone - 11700 Sulphur hexafluoride, SF66 23900 - depleting gases ~ 36 % HCFC-22 production ~ 27 % Electrical transmission and production ~ 17 % HELSINKI

Zevenhoven, Ron

260

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

261

Radiative relativistic shock adiabate  

SciTech Connect

The influences of thermal radiation on the state equation of shock waves, derived in the previous paper [L. N. Tsintsadze, Phys. Plasmas {bold 2}, 4462 (1995)], are studied and a series of relations of thermodynamic quantities that hold for shock waves are derived. It is shown that the presence of radiation can strongly change the compressibility of the plasma. It is well known that for polytropic gases the compressibility cannot change more than four times the initial value in the case of nonrelativistic temperatures. The numerical calculations show that there are no such restrictions, when the radiation energy exceeds the kinetic energy of the plasma. The ultrarelativistic temperature range is also covered in our numerical calculations. Also studied are the influences of the radiation on the PT and the TV diagrams. A significant modification due to radiation is found in every case studied. {copyright} {ital 1997 American Institute of Physics.}

Tsintsadze, L.N.; Nishikawa, K. [Faculty of Science, Hiroshima University, Higashihiroshima-City 1739 (Japan)] [Faculty of Science, Hiroshima University, Higashihiroshima-City 1739 (Japan)

1997-03-01

262

49 CFR 229.43 - Exhaust and battery gases.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

263

49 CFR 229.43 - Exhaust and battery gases.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

264

49 CFR 229.43 - Exhaust and battery gases.  

Code of Federal Regulations, 2013 CFR

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

2013-10-01

265

49 CFR 229.43 - Exhaust and battery gases.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

266

Detectability of biosignature gases in the atmospheres of terrestrial exoplanets  

E-print Network

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

Messenger, Stephen Joseph

2013-01-01

267

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

268

Global radiative forcing from contrail cirrus  

NASA Astrophysics Data System (ADS)

Aviation makes a significant contribution to anthropogenic climate forcing. The impacts arise from emissions of greenhouse gases, aerosols and nitrogen oxides, and from changes in cloudiness in the upper troposphere. An important but poorly understood component of this forcing is caused by `contrail cirrus'--a type of cloud that consist of young line-shaped contrails and the older irregularly shaped contrails that arise from them. Here we use a global climate model that captures the whole life cycle of these man-made clouds to simulate their global coverage, as well as the changes in natural cloudiness that they induce. We show that the radiative forcing associated with contrail cirrus as a whole is about nine times larger than that from line-shaped contrails alone. We also find that contrail cirrus cause a significant decrease in natural cloudiness, which partly offsets their warming effect. Nevertheless, net radiative forcing due to contrail cirrus remains the largest single radiative-forcing component associated with aviation. Our findings regarding global radiative forcing by contrail cirrus will allow their effects to be included in studies assessing the impacts of aviation on climate and appropriate mitigation options.

Burkhardt, Ulrike; Kärcher, Bernd

2011-04-01

269

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

270

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

271

Structure of the Star with Ideal Gases  

E-print Network

In this paper, we provide a simplified stellar structure model for ideal gases, in which the particles are only driven by gravity. According to the model, the structural information of the star can be roughly solved by the total mass and radius of a star. To get more accurate results, the model should be modified by introducing other interaction among particles and rotation of the star.

Ying-Qiu Gu

2007-12-03

272

Toxicity of Pyrolysis Gases from Elastomers  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

273

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

274

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

275

Global Reactive Gases in the MACC project  

NASA Astrophysics Data System (ADS)

In preparation for the planned atmospheric service component of the European Global Monitoring for Environment and Security (GMES) initiative, the EU FP7 project Monitoring of Atmospheric Composition and Climate (MACC) developed a preoperational data assimilation and modelling system for monitoring and forecasting of reactive gases, greenhouse gases and aerosols. The project is coordinated by the European Centre for Medium-Range Weather Forecast (ECMWF) and the system is built on ECMWF's Integrated Forecasting System (IFS) which has been coupled to the chemistry transport models MOZART-3 and TM5. In order to provide daily forecasts of up to 96 hours for global reactive gases, various satellite retrieval products for ozone (total column and profile data), CO, NO2, CH2O and SO2 are either actively assimilated or passively monitored. The MACC system is routinely evaluated with in-situ data from ground-based stations, ozone sondes and aircraft measurements, and with independent satellite retrievals. Global MACC reactive gases forecasts are used in the planning and analysis of large international field campaigns and to provide dynamical chemical boundary conditions to regional air quality models worldwide. Several case studies of outstanding air pollution events have been performed, and they demonstrate the strengths and weaknesses of chemical data assimilation based on current satellite data products. Besides the regular analyses and forecasts of the tropospheric chemical composition, the MACC system is also used to monitor the evolution of stratospheric ozone. A comprehensive reanalysis simulation from 2003 to 2010 provides new insights into the interannual variability of the atmospheric chemical composition.

Schultz, M. G.

2012-04-01

276

Air pollution, greenhouse gases and climate change: Global and regional perspectives  

Microsoft Academic Search

Greenhouse gases (GHGs) warm the surface and the atmosphere with significant implications for rainfall, retreat of glaciers and sea ice, sea level, among other factors. About 30 years ago, it was recognized that the increase in tropospheric ozone from air pollution (NOx, CO and others) is an important greenhouse forcing term. In addition, the recognition of chlorofluorocarbons (CFCs) on stratospheric ozone

V. Ramanathan; Y. Feng

2009-01-01

277

Spectroscopic diagnostics of barrier-discharge plasma in mixtures of cadmium diiodide vapor with gases  

NASA Astrophysics Data System (ADS)

The spectral characteristics of the emission of atmospheric-pressure gas-discharge plasma in mixtures of cadmium diiodide vapor with gases (Ne, Ar, Kr, Xe, and N2) were investigated along with the time characteristics of the voltage and current. The gas-discharge plasma was produced and excited by a barrier discharge at a repetition rate of sine voltage pulses of up to 140 kHz. The discharge emission was analyzed in the spectral range 200 900 nm with a high resolution (0.05 nm). Radiation from exciplex CdI(B-X) molecules and excimer I2* molecules was revealed, as well as the atomic lines of cadmium, iodine, and inert gases. In a mixture with xenon, radiation from exciplex molecules XeI(B-X, B-A) was also found. This radiation prevailed in the spectra at mixture temperatures up to 150°C. The further increase of the temperature leads to the prevalence of the CdI(B-X) radiation. It was found that the most intense CdI(B-X) radiation is observed in mixtures CdI2/Xe(N2)/Ne. Regularities in the spectral characteristics of the emission of the gas-discharge plasma are discussed.

Guivan, M. M.; Malinin, A. N.

2007-02-01

278

Experimental studies concerning the drying of voloxidizer off-gases  

SciTech Connect

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

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

1981-07-01

279

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

280

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

Microsoft Academic Search

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

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

1984-01-01

281

Two Radiative/Thermochemical Instruments  

NASA Technical Reports Server (NTRS)

Measurements of absorption and emission complement thermal measurements. Two laboratory instruments for research in combustion and pyrolysis equipped for radiative as well as thermal measurements. One instrument essentially differential scanning calorimeter (DSC) modified to detect radiation emitted by flames. Provides means to evaluate limits of flammability of materials exhibiting exothermic reactions in DSC's. Other instrument used to determine pyrolysis properties of specimens exposed to various gases by measurement of infrared absorption spectra of pyrolysis products.

Tapphorn, Ralph M.; Janoff, Dwight D.; Shelley, Richard M.

1990-01-01

282

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

NASA Technical Reports Server (NTRS)

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

Palosz, W.

2003-01-01

283

Inspection of non-CO 2 greenhouse gases from emission sources and in ambient air by Fourier-transform-infrared-spectrometry: Measurements with FTIS-MAPS  

Microsoft Academic Search

Infrared spectrometry is a versatile basis to analyse greenhouse gases in the atmosphere. A multicomponent air pollution software (MAPS) was developed for retrieval of gas concentrations from radiation emission as well as absorption measurements. Concentrations of CO, CH4, N2O, and H2O as well as CO2, NO, NO2, NH3, SO2, HCl, HCHO, and the temperature of warm gases are determined on-line.

Klaus Schäfer; Rainer Haus; Jörg Heland

1994-01-01

284

What are functional ionic liquids for the absorption of acidic gases?  

PubMed

As a kind of novel and efficient material, ionic liquids (ILs) are used for capture of acidic gases including SO2 and CO2 from flue gas. Due to very low content of acidic gases in flue gas, it is important to find functional ILs to absorb the acidic gases. However, up to now, there is no criterion to distinguish if the ILs are functional or not before use, which greatly influences the design of functional ILs. In this work, a series of ILs were synthesized and used to determine functional or normal ILs for the capture of acidic gases. It has been found that the pKa of organic acids forming the anion of ILs can be used to differentiate functional ILs from normal ILs for the capture of acidic gases from flue gas. If the pKa of an organic acid is larger than that of sulfurous acid (or carbonic acid), the ILs formed by the organic acid can be called functional ILs for SO2 (or CO2) capture, and it can have a high absorption capacity of SO2 (or CO2) with low SO2 (or CO2) concentrations. If not, the IL is just a normal IL. The pKa of organic acids can also be used to explain the absorption mechanism and guide the synthesis of functional ILs. PMID:23360403

Ren, Shuhang; Hou, Yucui; Tian, Shidong; Chen, Xiumei; Wu, Weize

2013-02-28

285

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

286

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

287

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

288

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

Code of Federal Regulations, 2013 CFR

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

2013-10-01

289

Transverse spin diffusion in strongly interacting Fermi gases  

NASA Astrophysics Data System (ADS)

We compute spin diffusion in a dilute Fermi gas at arbitrary temperature, polarization, and strong interaction in the normal phase using kinetic theory. While the longitudinal spin diffusivity D? depends weakly on polarization and diverges for small temperatures, the transverse spin diffusivity D? has a strong polarization dependence and approaches a finite value for T?0 in the Fermi liquid phase. For a 3D unitary Fermi gas at infinite scattering length, the diffusivities reach a minimum near the quantum limit of diffusion ?/m in the quantum degenerate regime and are strongly suppressed by medium scattering, and we discuss the importance of the spin-rotation effect. In two dimensions, D? attains a minimum at strong coupling -1?ln(kFa2D)?1 and reaches D?˜0.2...0.3?/m at large polarization. These values are consistent with recent measurements of two-dimensional ultracold atomic gases in the strong coupling regime.

Enss, Tilman

2013-09-01

290

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

291

Preserving noble gases in a convecting mantle.  

PubMed

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

Gonnermann, Helge M; Mukhopadhyay, Sujoy

2009-05-28

292

Toxicity of pyrolysis gases from wood  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

293

Optical remote measurement of toxic gases  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

294

Apparatus Measures Permeation Of Gases Through Coupons  

NASA Technical Reports Server (NTRS)

Apparatus measures permeation of any variety of commercially available pure or mixed gases through polymeric or other material coupons of various thicknesses. Permeability measured at wide range of temperatures and pressures. Includes residual-gas-analyzer (RGA) sensor head and associated circuitry, and vacuum system. Also includes manifold with valves, through which gas of interest allowed to permeate through test coupon before traveling downstream to evacuated RGA sensor head. Temperature of test coupon monitored by thermocouple and maintained at specified value above ambient by use of electrical heating mantle or below ambient by use of bath of ethylene glycol, water, and dry ice.

Adam, Steven J.; Morrow, Jim T.; David, Carey E.

1995-01-01

295

Toxicity of pyrolysis gases from polytetrafluoroethylene  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

296

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

297

Electron-impact excitation of atmospheric gases  

NASA Astrophysics Data System (ADS)

Electron energy-loss and impact-induced emission techniques were used to investigate excitation of key features in molecular nitrogen and rare gases. Specifically, line and band emission intensities were investigated as a function of wavelength (at high resolution) and incident electron energy using various monochromator-detector combinations. In addition, electron energy-loss spectroscopy was utilized such that differential cross sections (DCSs) and integral cross sections (ICSs) were obtained. The emission cross sections, DCSs, and ICSs for these atmospheric species will be presented.

Malone, Charles P.; Young, Jason A.; Johnson, Paul V.; Liu, Xianming; Kanik, Isik; Ajdari, Bahar; Khakoo, Murtadha A.

2010-03-01

298

Thermalization of atomic particles in gases  

SciTech Connect

A model of the atomic particle thermalization process due to scattering in various gases with application of the Born-Mayer potential is presented. The thermalization process of atomic particles using the statistical modeling method is considered. Our thermalization model is adapted to a wide class of atomic collision partners, takes into account the real energy and angular distributions of atomic particle sources, and makes it possible to calculate the parameters of the spatial zone of their thermalization and transfer into the diffusion motion mode. The energy range of applicability for the atomic particle thermalization model is interesting for many applied problems in plasma physics, gas discharge, and ion plating processes.

Volpyas, V. A., E-mail: volpyas@yandex.ru; Kozyrev, A. B. [St. Petersburg State Electrotechnical Institute (LETI) (Russian Federation)

2011-07-15

299

Topological phenomena in ultracold atomic gases  

E-print Network

is the dynamical phase factor that depends on how fast the particle moves. The first exponential is a geometrical phase factor, which only depends on the path travelled. This can be seen by substituting Eq. 1.1 into the time-dependent Schrodinger equation, i~ ??t... ?T > a¯ where a¯ is the average interparticle distance, ?T = ? 2pi~2 MkBT is the thermal de Broglie wavelength, M is the particle mass, kB is the Boltzmann constant and T is the temperature[8]. Section 1.2 Ultracold Atomic Gases 13 duce some relevant...

Price, Hannah

2013-10-08

300

Hydrodynamics and universality in cold atomic gases  

NASA Astrophysics Data System (ADS)

Recent flurry of experiments on out-of-equilibrium dynamics in cold gases (Bosonic and Fermionic) has raised great interest in understanding collective behaviour of interacting particles. Although the dynamics of interacting gases depends on many details of the system, a great insight can be obtained in a rather universal limit of weak non-linearity, dispersion and dissipation. In this limit, using a reductive perturbation method we map many hydrodynamic models relevant to cold atoms to well known chiral one-dimensional equations such as Korteweg-de Vries (KdV), Burgers, KdV-Burgers, and Benjamin-Ono equations. This mapping [1] of rather complicated hydrodynamic equations to known chiral one-dimensional equations is of great experimental and theoretical interest. For instance, this mapping gives a simple way to make estimates for original hydrodynamic equations and to study phenomena such as shock waves, solitons and the interplay between nonlinearity, dissipation and dispersion. All these phenomena have been observed in experiments and are the hallmarks of nonlinear hydrodynamics.[4pt] [1] M. Kulkarni, A. G. Abanov, Phys. Rev. A 86, 033614 (2012)

Abanov, Alexander; Kulkarni, Manas

2013-03-01

301

Spin-Orbit Coupled Quantum Gases  

NASA Astrophysics Data System (ADS)

In this talk I will discuss both spin-orbit coupled Bose condensate and degenerate Fermi gases. In the first part of this talk, I will discuss bosons with Rashba type spin-orbit coupling. We find the ground state exhibits two distinct non-trivial phases: the plane wave phase and the stripe superfluid phase. And the finite temperature thermal fluctuations can lead to an even more interesting boson paired superfluid state with half vortices. I will further discuss collective mode of spin-orbit coupled condensate. We find the dipole modes of a BEC is no longer harmonic due to the non-abelian nature of the gauge potential, and there will be a magnetization oscillation synchronized to the dipole motion due to the absence of Galilean invariance. Macroscopic quantum tunneling will also take place during the dipole oscillation. In the second part of this talk, I will discuss degenerate Fermi gases and the BEC-BCS crossover with spin-orbit coupling. I will talk about spin dephasing and interaction effects in the Raman induced spin dynamics, and the topological change of Fermi surfaces. I will emphasize that Rashba spin-orbit coupling can significantly enhance the pairing strength and the superfluid transition temperature.

Zhai, Hui

2012-06-01

302

Immediate ignition smokeless burning of waste gases  

SciTech Connect

An apparatus for immediate ignition of waste gases and their smokeless burning which is built into a cylindrical stack, for the flow of waste gases. Near the top of the stack, there is positioned, coaxially, a steam-air pipe for supplying a mixture of steam and air. The steam and air are introduced into the pipe, by means of radial tubes, connected to a circular manifold on the outside of the stack. A circular cover plate or baffle over the steam-air pipe is supported by a plurality of broad strips equally spaced circumferentially, around the periphery of the steam-air pipe. There are a plurality of radial support arms between the stack and the steam-air pipe. These can be made from angle iron of sufficient width, the purpose being to deflect upwardly flow of the annular column of gas, to break it into a plurality of spaced circular segments of gas, the space above the arms protects a stable flame, for instant reignition of the mixture of gas, air and steam.

Reed, R.D.; Schwartz, R.E.

1983-02-15

303

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

304

Performance Audits of EPA Protocol Gases and Inspection and Maintenance Calibration Gases  

Microsoft Academic Search

Two performances audits of calibration gas mixtures were conducted by RTI in 1985 to assess the accuracy of certified concentrations assigned by speciality gas producers. The first audit involved the purchase and analysis of EPA Protocol No. 1 gases from 11 specialty gas producers. These mixtures contained sulfur dioxide in nitrogen, nitric oxide in nitrogen, and carbon monoxide in air.

Robert S. Wright; Edward L. Tew; Clifford E. Decker; Darryl J. von Lehmden; William F. Barnard

1987-01-01

305

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

306

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

PubMed Central

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

Gadani, Hina; Vyas, Arun

2011-01-01

307

Why Are Teams Important?  

NASA Video Gallery

Kelvin Kirby, deputy director for the Center for Radiation Engineering and Science for Space Exploration, or CRESSE, at Prairie View A&M University, explains how the complexity of space radiation m...

308

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

309

Detection of volcanic gases and particles by satellite  

NASA Astrophysics Data System (ADS)

In this paper the detection of components of volcanic eruption has been carried out investigating, in appropriate bands of the electromagnetic spectrum (6.25, 8.7, 10.8, 12 ?m), the values of the brightness temperature. The analysis has been performed in the Thermal Infrared Region (TIR) studying both the absorption-emission and scattering phenomena related to the interactions between electromagnetic radiation and volcanic emissions. The results have been achieved by means of a combined use of numerical simulations, devoted to examining the behaviour of the atmosphere gases and volcanic components, and remotely sensed satellite images. The proposed methodologies allow an estimate of the amount of gaseous and solid components, of the size of the emitted particles, of the height of the volcanic plume and of the distance of the volcanic components from the crater. The processed images come from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) sensor on board the geo-stationary satellite Meteosat Second Generation (MSG) and take into consideration an eruption of the Etna volcano as a study case (1st of April 2012, 04:30 and 05:30 UTC). The procedures are general and may therefore be extended to any other similar case.

Ortore, Emiliano; Laneve, Giovanni; Bernini, Guido

2014-01-01

310

Snowpack Chemistry of Reactive Gases at Station Concordia, Antarctica  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

311

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

312

Veracruz State Preliminary Greenhouse Gases Emissions Inventory  

NASA Astrophysics Data System (ADS)

At recent years, the international organisms such as United Nations, has discussed that the temperature has increased slightly and the pattern of precipitations has changed in different parts of the world, which cause either extreme droughts or floods and that the extreme events have increased. These are some of the risks of global climate change because of the increase of gas concentration in the atmosphere such as carbon dioxides, nitrogen oxides and methane - which increase the greenhouse effect. Facing the consequences that could emerge because of the global temperature grown, there is a genuine necessity in different sectors of reduction the greenhouse gases and reduced the adverse impacts of climate change. To solve that, many worldwide conventions have been realized (Rio de Janeiro, Kyoto, Montreal) where different countries have established political compromises to stabilize their emissions of greenhouse gases. The mitigation and adaptation policies merge as a response to the effects that the global climate change could have, on the humans as well as the environment. That is the reason to provide the analysis of the areas and geographic zones of the country that present major vulnerability to the climate change. The development of an inventory of emissions that identifies and quantifies the principal sources of greenhouse gases of a country, and also of a region is basic to any study about climate change, also to develop specific political programs that allow to preserve and even improve a quality of the atmospheric environment, and maybe to incorporate to international mechanisms such as the emissions market. To estimate emissions in a systematic and consistent way on a regional, national and international level is a requirement to evaluate the feasibility and the cost-benefit of instrumented possible mitigation strategies and to adopt politics and technologies to reduce emissions. Mexico has two national inventories of emissions, 1990 and 1995, now it is on the press the year 2000, both published by the National Institute of Ecology of the SEMARNAT. There is not an emissions inventory of Veracruz, the few measurements campaigns that have been done in urban centers, it has not been possible to have access data, neither it has been designed a public politic that suggests the necessity of counting on information on the matter. In spite of it, because of the geographic conditions of Veracruz, the potential impact will transform Veracruz in a short period of time, that’s why the Veracruz University must leadership studies around it, where the social distribution of the obtained results will make possible the creation of politics, strategies directed to a sustainable development, economically viable, socially fair and environmentally respectful.

Welsh Rodriguez, C.; Rodriquez Viqueira, L.; Guzman Rojas, S.

2007-05-01

313

Hydrogen Peroxide Enhances Removal of NOx from Flue Gases  

NASA Technical Reports Server (NTRS)

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

Collins, Michelle M.

2005-01-01

314

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

SciTech Connect

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

Kiehl, J. T.

2004-03-31

315

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

316

Industrial gases offer new processing alternatives  

SciTech Connect

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

Jackow, F.

1996-07-01

317

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

318

Upper ocean model of dissolved atmospheric gases  

SciTech Connect

The goal of this project is to estimate the rate of biological oxygen production at Hawaiian Ocean Time-series station ALOHA in the central North Pacific ocean. Our approach is to use an upper ocean model together with measurements to interpret an annual cycle of temperature, salinity, dissolved oxygen, argon, nitrogen, and the stable isotope ratio of oxygen at station ALOHA. This project represents the first upper ocean geochemical study in which model predictions are verifiable by independent measurements. Using the model, we will be able to assess the relative roles played by physical processes (air-sea gas exchange, air injection by bubbles, temperature-induced changes in gas solubility, trapping below the mixed layer, and diffusion) and biological processes (photosynthesis, respiration, and nutrient recycling) in producing the observed distribution of dissolved atmospheric gases. The long term goal of this project is to understand the utility of chemical tracers for quantifying biological processes in the ocean.

Schudlich, R.; Emerson, S.

1992-01-01

319

Biomedical imaging with hyperpolarized noble gases  

NASA Astrophysics Data System (ADS)

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.

Ruppert, Kai

2014-11-01

320

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

321

Removing arsenic from copper smelter gases  

NASA Astrophysics Data System (ADS)

The pyrometallurgical processing of nonferrous minerals found in association with sulfur and arsenic generates arsenic-bearing SO2 gases. Effective process gas cleaning presents technical problems due to the high volatility of the As2O3 compound and the elevated dew point of the sulfur-trioxidecontaining SO2 gas. Critical factors for gascleaning technology selection pertaining to technical feasibility, economic acceptability, and environmental compatibility are the arsenic-to-sulfur ratio in the feed material, the operating parameters of the pyrometallurgical and gas cooling process, the admissible arsenic concentration of the SO2 gas after arsenic elimination, and the most suitable form of the arsenic-bearing output material. Depending on these factors, the bulk of the arsenic can be eliminated from the process gas in concentrated form according to either the dry or wet method, after which final arsenic removal from the process gas to below the required admissible level must take place in a wet electrostatic precipitator.

Dalewski, Frank

1999-09-01

322

Entanglement and decoherence in spin gases  

E-print Network

We study the dynamics of entanglement in spin gases. A spin gas consists of a (large) number of interacting particles whose random motion is described classically while their internal degrees of freedom are described quantum-mechanically. We determine the entanglement that occurs naturally in such systems for specific types of quantum interactions. At the same time, these systems provide microscopic models for non--Markovian decoherence: the interaction of a group of particles with other particles belonging to a background gas are treated exactly, and differences between collective and non--collective decoherence processes are studied. We give quantitative results for the Boltzmann gas and also for a lattice gas, which could be realized by neutral atoms hopping in an optical lattice. These models can be simulated efficiently for systems of mesoscopic sizes (N ~ 10^5).

J. Calsamiglia; L. Hartmann; W. Dür; H. -J. Briegel

2005-02-01

323

Entanglement and decoherence in spin gases  

E-print Network

We study the dynamics of entanglement in spin gases. A spin gas consists of a (large) number of interacting particles whose random motion is described classically while their internal degrees of freedom are described quantum-mechanically. We determine the entanglement that occurs naturally in such systems for specific types of quantum interactions. At the same time, these systems provide microscopic models for non--Markovian decoherence: the interaction of a group of particles with other particles belonging to a background gas are treated exactly, and differences between collective and non--collective decoherence processes are studied. We give quantitative results for the Boltzmann gas and also for a lattice gas, which could be realized by neutral atoms hopping in an optical lattice. These models can be simulated efficiently for systems of mesoscopic sizes (N ~ 10^5).

Calsamiglia, J; Dür, W; Briegel, H J

2005-01-01

324

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.

325

Universality classes of driven lattice gases  

NASA Astrophysics Data System (ADS)

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

Garrido, Pedro L.; Muñoz, Miguel A.; de Los Santos, F.

2000-05-01

326

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

327

An Improved Radiation Pyrometer  

Microsoft Academic Search

In designing a new radiation pyrometer for industrial use above the lower limit of visible radiation, consideration of ambient temperature effects, which is of much importance in modern industrial practice, was carried out by aid of mathematical analysis. In one hypothetical case, with a very sensitive type of thermopile losing heat from its hot junction by radiation alone, it is

Thos. R. Harrison; Wm. H. Wannamaker

1941-01-01

328

Notes on synchrotron radiation  

E-print Network

I comment on a number of theoretical issues related to magnetobremsstrahlung, and especially on synchrotron radiation and Unruh (temperature) radiation, that I consider of importance for the current progress towards a better understanding of the stationary features of such fundamental radiation patterns both in an accelerator context and, more generally, in the physical world

H. C. Rosu

1994-12-11

329

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

NASA Technical Reports Server (NTRS)

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

Palosz, Witold

1998-01-01

330

The Importance of Water Uptake by Aerosols in the Climate Change Problem  

NASA Astrophysics Data System (ADS)

It is well understood that aerosol species have and are continuing to play a central role in the radiative forcing of the climate system. While the role of single-scattering properties of aerosols on climate is generally well- recognized, a key factor that governs the aerosol optical property viz., the hygroscopic growth has received insufficient attention particularly in terms of its role in the climatic impacts due to aerosols. A sensitivity investigation is performed that quantitatively highlights the consequence of the growth of sea-salt-organic carbon mixtures for radiative forcing. Next, we employ the GFDL coupled atmosphere-ocean model to study specifically the aerosol radiative forcing and climate response arising due to the hygroscopic features of sulfate aerosols as they have increased from preindustrial to present-day. We make use of observations of optical depth and surface concentrations to evaluate the reliability of the simulated hygroscopic growth. Regional climate responses in Europe, Asia and Africa are examined, with a focus on temperature, hydrological cycle and surface energy budgets. The importance of hygroscopicity in the climate change problem is put in perspective by comparing the climatic effects with those due to aerosol absorption as well as with those caused by the infrared-absorbing long- lived greenhouse gases. Further, we explore the climate consequence arising from the scenarios of the future emissions of aerosols and the associated hygroscopicity effects.

Ramaswamy, V.; Ginoux, P.; Randles, C.; Schwarzkopf, M. D.

2007-12-01

331

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

332

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

333

Isotopic studies of rare gases in terrestrial samples and natural nucleosynthesis  

SciTech Connect

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

Not Available

1990-07-01

334

Characterisation of Q-gases and other noble gas components in the Murchison meteorite  

NASA Technical Reports Server (NTRS)

Noble gases in several HF/HCl resistant residues of the CM2 chondrite Murchison were measured by closed-system stepped etching, in order to study the planetary gases in their major carrier 'Q'-an ill-defined minor phase, perhaps merely a set of adsorption sites. Neon, Ar, Kr, Xe, and probably also He in 'Q' of Murchison have the same isotopic and nearly the same elemental abundances as their counterparts in Allende (CV3). The isotopic composition of Ne-Q is consistent with mass-dependent fractionation of either solar wind Ne or Ne from solar energetic particles. Unlike Allende, Murchison during HNO3 attack release, besides Q-gases, large amounts of two other Ne-components, Ne-E and Ne-A3, a third subcomponent of Ne-A. This work confirms that Q-gases of well-defined composition were an important noble gas component in the early solar system an are now found in various classes of meteorites, such as carbonaceous chondrites, ureilites, and ordinary chondrites. Ne-Q may have played a role in the formation of noble gas reservoirs in terrestrial planets.

Wieler, Rainer; Anders, Edward; Baur, Heinrich; Lewis, Roy S.; Signer, Peter

1992-01-01

335

Introduction Importance of temperature in streams  

E-print Network

Department, Office of Watersheds, Philadelphia PA 19107, USA #12;and riparian vegetation radiation, airIntroduction Importance of temperature in streams Stream temperature affects microfauna survival, fish reproduction, and aquatic metabolism rates. Nearly every species is temperature sensitive

Toran, Laura

336

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

337

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

338

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

339

Fullerenes and Noble Gases in the Murchison and Allende Meteorites  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

340

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

...HAZARDOUS MATERIALS REGULATIONS CARRIAGE BY RAIL Detailed Requirements for Class 2 (Gases...gases) materials being transported in a rail car must be: (1) Securely lashed...subchapter) cylinders being transported in a rail car must be loaded in an upright...

2014-10-01

341

Low-drag airfoils for transonic flow of dense gases  

Microsoft Academic Search

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

Zvi Rusak; Chun-Wei Wang

2000-01-01

342

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...

343

EPA'S QA PROGRAM ON THE SUPPLIERS 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 PA Protocol Gases. he program has three goals: to ncrease he cceptance and use of Protocol Gases by the air monitoring ommunity, to provide a QA check for ...

344

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

345

Fundamental Electrical Properties or Mercury Vapor and Monatomic Gases  

Microsoft Academic Search

Electrical properties of mercury vapor and monatomic gases are discussed from a theoretical standpoint in this article. In the first part of the article, the author discusses briefy the elementary processes of excitation and ionization of atoms upon which the electrical properties of gases depend. With this insight into the fundamental processes as a 1, ackground, the author discusses in

Albert W. Hull

1934-01-01

346

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

347

Measurement of transient nonlinear refractive index in gases using xenon  

E-print Network

Measurement of transient nonlinear refractive index in gases using xenon supercontinuum single measurement of ultrafast high field processes using modest energy lasers, with pump and probe pulses totaling) and instrument resolution. The ultrafast nonlinear Kerr effect in glass, and in Ar, N2, and N2O gases is measured

Milchberg, Howard

348

A Simple Experiment to Demonstrate the Effects of Greenhouse Gases  

ERIC Educational Resources Information Center

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

Keating, C. F.

2007-01-01

349

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

350

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

351

AMIII Termodinamica dos Gases Ideais 17 de Janeiro de 2002  

E-print Network

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

Natário, José

352

Field Observations of the Processing of Organic Aerosol Particles and Trace Gases by Fogs and Clouds  

NASA Astrophysics Data System (ADS)

In many environments, organic compounds account for a significant fraction of fine particle mass. Because the lifetimes of accumulation mode aerosol particles are governed largely by interactions with clouds, it is important to understand how organic aerosol particles are processed by clouds and fogs. Recently we have examined the organic composition of clouds and fogs in a variety of environments as well as how these fogs and clouds process organic aerosol particles and soluble organic trace gases. The investigations, conducted in Europe, North America, Central America, and the Pacific region, have included studies of polluted radiation fogs, orographic clouds in clean and polluted environments, and marine stratocumulus. Our results show that organic matter is a significant component of fog and cloud droplets. In polluted California radiation fogs, we observed concentrations of total organic carbon (TOC) ranging from 2 to 40 ppmC, with significantly lower concentrations measured in marine and continental clouds. An average of approximately 80 percent of organic matter was found in solution, while the remainder appears to be suspended material inside cloud and fog drops. Ultrafiltration measurements indicate that as much as half of the dissolved organic carbon is present in very large molecules with molecular weights in excess of 500 Daltons. Field measurements made using a two-stage cloud water collector reveal that organic matter tends to be enriched in smaller cloud or fog droplets. Consequently, removal of organic compounds by precipitating clouds or by direct cloud/fog drop deposition will be slowed due to the fact that small drops are incorporated less efficiently into precipitation and removed less efficiently by sedimentation or inertial impaction. Despite this trend, we have observed that sedimentation of droplets from long-lived radiation fogs provides a very effective mechanism for cleansing the atmosphere of carbonaceous aerosol particles, with organic carbon removed more efficiently than elemental carbon. Efforts to characterize organic matter in clouds and fogs reveal that the most abundant species are typically low molecular weight carboxylic acids and aldehydes. These species have been observed collectively to account for roughly 20-30 percent of the total organic carbon in some fogs and clouds. Dicarboxylic acids, frequently used as model compounds for organic CCN, typically account for only about 1 percent of the organic carbon, with oxalic acid the most important contributor. Measurements by GC/MS, HPLC, and H-NMR reveal that many other organic compounds are present, including aerosol source markers and compound families frequently detected in aerosol particles including n-alkanes, n-alkanoic acids, and polycyclic aromatic hydrocarbons. These latter compounds were detected in both dissolved and undissolved forms in droplets, with dissolved concentrations often higher than their solubilities in pure aqueous solutions, suggesting a possible role of surface organic films. Although more than 100 organic species have been quantified in many samples, the majority of the organic carbon mass remains unspeciated. Given the importance of high molecular weight material, future efforts will focus in part on further characterization of these compounds, including possible contributions from humic like substances.

Collett, J. L.; Herckes, P.

2003-12-01

353

Management of radiation maculopathy.  

PubMed

Radiation maculopathy is a delayed onset complication of radiation exposure. Various host and radiation parameters determine the risk of developing radiation maculopathy, which may be progressive. Total radiation dose delivered to the macula is the most important modifiable factor. Radiation maculopathy is not a singular entity as clinical manifestations reflect combined effects of all damaged tissues. Current treatment using anti-vascular endothelial growth factor agents offers only a short-term, temporary, and modest visual improvement. Avoidance or prevention of radiation maculopathy may be the best option. Use of periocular steroid during plaque brachytherapy may prevent radiation maculopathy over the short term. Newer designs and techniques of delivering radiation to the eye need to be explored. PMID:22907147

Singh, Arun D; Pabon, Sheila; Aronow, Mary E

2012-01-01

354

Analytical methods for toxic gases from thermal degradation of polymers  

NASA Technical Reports Server (NTRS)

Toxic gases evolved from the thermal oxidative degradation of synthetic or natural polymers in small laboratory chambers or in large scale fire tests are measured by several different analytical methods. Gas detector tubes are used for fast on-site detection of suspect toxic gases. The infrared spectroscopic method is an excellent qualitative and quantitative analysis for some toxic gases. Permanent gases such as carbon monoxide, carbon dioxide, methane and ethylene, can be quantitatively determined by gas chromatography. Highly toxic and corrosive gases such as nitrogen oxides, hydrogen cyanide, hydrogen fluoride, hydrogen chloride and sulfur dioxide should be passed into a scrubbing solution for subsequent analysis by either specific ion electrodes or spectrophotometric methods. Low-concentration toxic organic vapors can be concentrated in a cold trap and then analyzed by gas chromatography and mass spectrometry. The limitations of different methods are discussed.

Hsu, M.-T. S.

1977-01-01

355

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.

356

Diurnal cycle of greenhouse gases and biogenic hydrocarbons during summer near Cool, CA  

NASA Astrophysics Data System (ADS)

Photosynthesis by forests is a large sink for atmospheric carbon dioxide (CO2) and also a large source of biogenic volatile organics (VOCs) that produce aerosols, nucleate clouds, and interact with nitrogen oxides (NOx) to produce ozone. To elucidate these complex biogeochemical mechanisms, we performed continuous high temporal resolution measurements of CO2, VOC, trace gases, and aerosol in June 2010 at the T1 site, 70 km from Sacramento, CA, during the Carbonaceous Aerosol and Radiative Effects Study (CARES) in June 2010. Throughout the month we find that diurnal profiles exhibit minima in CO2 and maxima in isoprene during daytime. Both their amplitudes are modulated strongly by cloud cover consistent with a common photosynthetic mechanism. In contrast, we find that diurnal monoterpene profiles peak at night while CO2 is at its maxima. Their amplitudes are modulated by temperature and boundary layer height. The monoterpenes and CO2 cycle show larger increases at warmer temperatures, suggesting respiration as a common driver. Additional measurements of CH4, CO, benzene, toluene, NO, NOy and O3 are used to define biogeochemical cycling of greenhouse gases and are demonstrated as a baseline for separating anthropogenic and biogenic emissions and observing transport of greenhouse gases and air pollution.

Flowers, B. A.; Floerchinger, C.; Knighton, W. B.; Dubey, M. K.; Herndon, S. C.; Kelley, P.; Luke, W. T.; Shaw, W. J.; Barnard, J.; Laulainen, N.; Zaveri, R. A.

2010-12-01

357

Accounting for carbon cycle feedbacks in a comparison of the global warming effects of greenhouse gases  

NASA Astrophysics Data System (ADS)

Greenhouse gases other than CO2 make a significant contribution to human-induced climate change, and multi-gas mitigation strategies are cheaper to implement than those which limit CO2 emissions alone. Most practical multi-gas mitigation strategies require metrics to relate the climate warming effects of CO2 and other greenhouse gases. Global warming potential (GWP), defined as the ratio of time-integrated radiative forcing of a particular gas to that of CO2 following a unit mass emission, is the metric used in the Kyoto Protocol, and we define mean global temperature change potential (MGTP) as an equivalent metric of the temperature response. Here we show that carbon-climate feedbacks inflate the GWPs and MGTPs of methane and nitrous oxide by ~ 20% in coupled carbon-climate model simulations of the response to a pulse of 50 × 1990 emissions, due to a warming-induced release of CO2 from the land biosphere and ocean. The magnitude of this effect is expected to be dependent on the model, but it is not captured at all by the analytical models usually used to calculate metrics such as GWP. We argue that the omission of carbon cycle dynamics has led to a low bias of uncertain but potentially substantial magnitude in metrics of the global warming effect of other greenhouse gases, and we suggest that the carbon-climate feedback should be considered when greenhouse gas metrics are calculated and applied.

Gillett, Nathan P.; Damon Matthews, H.

2010-07-01

358

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

USGS Publications Warehouse

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

Larson, D.L.

1994-01-01

359

Potential effects of anthropogenic greenhouse gases on avian habitas and populations in the northern Great Plains  

SciTech Connect

Biotic response to the buildup of greenhouse gases in Earth's atmosphere is considerably more complex than an adjustment to changing temperature and precipitation. The fertilization effect CO[sub 2] has on some plants, the impact UVB radiation has on health and productivity of organisms, and the resulting changes in competitive balance and trophic structure must also be considered. The intent of this paper is to review direct and indirect effects of anthropogenic greenhouse gases on wildlife, and to explore possible effects on populations of birds and their habitats in the northern Great Plains. Many of the potential effects of increasing greenhouse gases, such as declining plant nutritional value, changes in timing of insect emergence, and fewer and saltier wetlands, foreshadow a decline in avian populations on the Great Plains. However, other possible effects such as increased drought resistance and water use efficiency of vegetation, longer growing seasons, and greater overall plant biomass promise at least some mitigation. Effects of multiple simultaneous perturbations such as can be expected under doubled CO[sub 2] scenarios will require substantial basic research to clarify. 113 refs., 1 fig.

Larson, D.L. (Northern Prairie Wildlife Research Center, Jamestown, ND (United States))

1994-04-01

360

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

361

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

362

Ultracold Quantum Gases in Hexagonal Optical Lattices  

NASA Astrophysics Data System (ADS)

Hexagonal structures occur in a vast variety of systems, ranging from honeycombs of bees in life sciences to carbon nanotubes in material sciences. The latter, in particular its unfolded two-dimensional layer -- Graphene -- has rapidly grown to one of the most discussed topics in condensed-matter physics. Not only does it show proximity to various carbon-based materials but also exceptional properties owing to its unusual energy spectrum. In quantum optics, ultracold quantum gases confined in periodic light fields have shown to be very general and versatile instruments to mimic solid state systems. However, so far nearly all experiments were performed in cubic lattice geometries only. Here we report on the first experimental realization of ultracold quantum gases in a state-dependent, two-dimensional, Graphene-like optical lattice with hexagonal symmetry. The lattice is realized via a spin-dependent optical lattice structure with alternating ?^+ and ?^- -sites and thus constitutes a so called `magnetic'-lattice with `antiferromagnetic'-structure. Atoms with different spin orientation can be loaded to specific lattice sites or -- depending on the parameters -- to the whole lattice. As a consequence e.g. superpositions of a superfluid spin component with a different spin component in the Mott-insulating phase can be realized as well as spin-dependent transport properties, disorder etc. After preparing an antiferromagnetically ordered state we e.g. measure sustainable changes of the transport properties of the atoms. This manifests in a significant reduction of the tunneling as compared to a single-component system. We attribute this observation to a partial tunneling blockade for one spin component induced by population in another spin component localized at alternating lattice sites. Within a Gutzwiller-Ansatz we calculate the phase diagrams for the mixed spin-states and find very good agreement with our experimental results. Moreover, by state-resolved recording of the position of the atoms we observe a profound redistribution of the atoms in the lattice due to interstate interactions.

Sengstock, Klaus

2010-03-01

363

Observation of intermixing at the buried CdS\\/Cu(In, Ga)Se2 thin film solar cell heterojunction  

Microsoft Academic Search

A combination of x-ray emission spectroscopy and x-ray photoelectron spectroscopy using high brightness synchrotron radiation has been employed to investigate the electronic and chemical structure of the buried CdS\\/Cu(In, Ga)Se2 interface, which is the active interface in highly efficient thin film solar cells. In contrast to the conventional model of an abrupt interface, intermixing processes involving the elements S, Se,

C. Heske; D. Eich; R. Fink; E. Umbach; T. van Buuren; C. Bostedt; L. J. Terminello; S. Kakar; M. M. Grush; T. A. Callcott; F. J. Himpsel; D. L. Ederer; R. C. C. Perera; W. Riedl; F. Karg

1999-01-01

364

Measuring non-condensable gases in steam.  

PubMed

In surgery, medical devices that are used should be sterilized. To obtain surface steam sterilization conditions, not only in the sterilizer chamber itself but also in the loads to be sterilized, the amount of non-condensable gases (NCGs), for instance air, should be very low. Even rather small fractions of NCGs (below 1%) seriously hamper steam penetration in porous materials or devices with hollow channels (e.g., endoscopes). A recently developed instrument which might detect the presence of residual NCGs in a reliable and reproducible way is the 3M(TM) Electronic Test System (ETS). In this paper, a physical model is presented that describes the behavior of this instrument. This model has been validated by experiments in which known fractions of NCGs were introduced in a sterilizer chamber in which an ETS was placed. Despite several approximations made in the model, a good agreement is found between the model predictions and the experimental results. The basic principle of the ETS, measuring the heat transfer by condensation on a cooled surface, permits a very sensitive detection of NCGs in harsh environments like water vapor at high temperatures and pressures. Our model may serve to develop adapted and optimized versions of this instrument for use outside the field of sterilization, e.g., in heat exchangers based on steam condensation. PMID:24289436

van Doornmalen, J P C M; Kopinga, K

2013-11-01

365

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

366

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

367

Quantum gases in trimerized kagome lattices  

SciTech Connect

We study low-temperature properties of atomic gases in trimerized optical kagome lattices. The laser arrangements that can be used to create these lattices are briefly described. We also present explicit results for the coupling constants of the generalized Hubbard models that can be realized in such lattices. In the case of a single-component Bose gas the existence of a Mott insulator phase with fractional numbers of particles per trimer is verified in a mean-field approach. The main emphasis of the paper is on an atomic spinless interacting Fermi gas in the trimerized kagome lattice with two fermions per site. This system is shown to be described by a quantum spin-1/2 model on the triangular lattice with couplings that depend on the bond directions. We investigate this model by means of exact diagonalization. Our key finding is that the system exhibits nonstandard properties of a quantum spin-liquid crystal: it combines planar antiferromagnetic order in the ground state with an exceptionally large number of low-energy excitations. The possibilities of experimental verification of our theoretical results are critically discussed.

Damski, B. [Institut fuer Theoretische Physik, Universitaet Hannover, D-30167 Hannover (Germany); Theory Division, Los Alamos National Laboratory, MS-B213, Los Alamos, New Mexico 87545 (United States); Fehrmann, H.; Everts, H.-U. [Institut fuer Theoretische Physik, Universitaet Hannover, D-30167 Hannover (Germany); Baranov, M. [Van der Waals-Zeeman Instituut, Universiteit van Amsterdam, 1018 XE Amsterdam (Netherlands); Kurchatov Institute, Kurchatov square 1, 123182 Moscow (Russian Federation); Santos, L. [Institut fuer Theoretische Physik III, Universitaet Stuttgart, D-70550 Stuttgart (Germany); Lewenstein, M. [Institut fuer Theoretische Physik, Universitaet Hannover, D-30167 Hannover (Germany); ICFO-Institut de Ciencies Fotoniques, Jordi Girona 29, Edifici Nexus II, E-08034 Barcelona (Spain)

2005-11-15

368

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

369

health effects of dielectric gases: preliminary report  

SciTech Connect

The toxicity of various dielectric gases was assayed in two in vitro systems: Chinese hamster V79 (lung) cells (mammalian) and yeast (Saccharomyces cerevisiae). Exposures were carried out in small tubes which were constantly rotated, so that cells were exposed to the gas with only a thin layer of cell culture liquid covering them. Results indicate that SF/sub 6/ is essentially without cytotoxic effect on both systems. After discharge of 16 kJ total spark energy in 60 cm/sup 3/ of SF/sub 6/, the sparked samples were found to be cytotoxic to the mammalian cells, but not to the yeast. The toxicity of these sparked samples to the mammalian system was observed within 15 min of exposure of the cells and the degree of toxicity increased with time of exposure. In addition, increasing spark energy produced samples with increased cytotoxic activity. Yeast cells were unresponsive to octafluorocyclobutane (c-C/sub 4/F/sub 8/) and sparked SF/sub 6/. However, as little as 10% perfluoro-2-butyne (PFB) resulted in 100% toxic response to the yeast, and 95% hexafluorocyclobutene (c-C/sub 4/F/sub 6/) prevented their normal exponential growth, but did not result in mortality.

Easterly, C.E.; Dudney, C.S.; Griffin, G.D.; Walsh, P.J.

1982-08-01

370

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

SciTech Connect

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

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

2011-09-15

371

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

372

Neuroprotective gases--fantasy or reality for clinical use?  

PubMed

The neuroprotective properties for certain medical gases have been observed for decades, leading to extensive research that has been widely reported and continues to garner interest. Common gases including oxygen, hydrogen, carbon dioxide and nitric oxide, volatile anesthetics such as isoflurane, sevoflurane, halothane, enflurane and desflurane, non-volatile anesthetics such as xenon and nitrous oxide, inert gases such as helium and argon, and even gases classically considered to be toxic (e.g., hydrogen sulfide and carbon monoxide) have all been supported by the evidence alluding to their use as potential neuroprotective agents. A wide range of neural injury types such as ischemic/hemorrhagic, stroke, subarachnoid hemorrhage, traumatic brain injury, perinatal hypoxic-ischemic brain injuries, neurodegenerative disease as well as spinal cord ischemia have been used as platforms for studying the neuroprotective effects of these gases, yet until now, none of the gases has been widely introduced into clinical use specifically for protection against neural injury. Insufficient clinical data together with contradictory paradigms and results further hinders the clinical trials. However, pre-clinical models suggest that despite the various classes of gases and the broad range of injuries to which medical gases confer, protection, several underlying mechanisms for their neuroprotective properties are similar. In this review, we summarize the literature concerning the neuroprotective effect of each gas and its underlying mechanisms, extract common targets reported for the neuroprotective effects of different gases, highlight the conflicting observations from clinical trials and further discuss the possible hindrances impeding clinical applications in order to propose future research perspectives and therapeutic exploitations. PMID:24440817

Deng, Jiao; Lei, Chong; Chen, Yu; Fang, Zongping; Yang, Qianzi; Zhang, Haopeng; Cai, Min; Shi, Likai; Dong, Hailong; Xiong, Lize

2014-04-01

373

49 CFR 173.466 - Additional tests for Type A packagings designed for liquids and gases.  

Code of Federal Regulations, 2010 CFR

...Type A packagings designed for liquids and gases. 173.466 Section 173...Type A packagings designed for liquids and gases. (a) In addition to the...Type A packagings designed for liquids and gases must be capable of...

2010-10-01

374

40 CFR 60.54a - Standard for municipal waste combustor acid gases.  

Code of Federal Regulations, 2011 CFR

...municipal waste combustor acid gases. (a)-(b) [Reserved...from that affected facility any gases that contain sulfur dioxide...from that affected facility any gases that contain hydrogen chloride in excess of 5...

2011-07-01

375

40 CFR 60.54a - Standard for municipal waste combustor acid gases.  

Code of Federal Regulations, 2012 CFR

...municipal waste combustor acid gases. (a)-(b) [Reserved...from that affected facility any gases that contain sulfur dioxide...from that affected facility any gases that contain hydrogen chloride in excess of 5...

2012-07-01

376

40 CFR 60.54a - Standard for municipal waste combustor acid gases.  

Code of Federal Regulations, 2013 CFR

...municipal waste combustor acid gases. (a)-(b) [Reserved...from that affected facility any gases that contain sulfur dioxide...from that affected facility any gases that contain hydrogen chloride in excess of 5...

2013-07-01

377

40 CFR 60.54a - Standard for municipal waste combustor acid gases.  

Code of Federal Regulations, 2010 CFR

...municipal waste combustor acid gases. (a)-(b) [Reserved...from that affected facility any gases that contain sulfur dioxide...from that affected facility any gases that contain hydrogen chloride in excess of 5...

2010-07-01

378

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

379

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

380

Permeability of porous materials for liquid and gases  

NASA Astrophysics Data System (ADS)

It is shown that propagation of liquids and gases through a porous material has a different character, namely, the viscosity characterizes this process for liquids, whereas for gases it is determined by collisions of the gas molecules with the skeleton of the porous material. The analog of the Kozeny-Carman formula in liquids for the Darcy coefficient or the permeability coefficient is represented for gases. The transition between these limiting cases results from the relation between the mean free path of an individual molecule in a liquid or gas ? and the mean free path of this molecule with respect to its scattering on the skeleton of a porous material.

Krainov, V. P.; Smirnov, B. M.; Tereshonok, D. V.

2014-11-01

381

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

382

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

383

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

384

Thermal maps of gases in heterogeneous reactions.  

PubMed

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. PMID:24153305

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

2013-10-24

385

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

386

Mid-Infrared OPO for High Resolution Measurements of Trace Gases in the Mars Atmosphere  

NASA Technical Reports Server (NTRS)

The Martian atmosphere is composed primarily (>95%) of CO2 and N2 gas, with CO, O2, CH4, and inert gases such as argon comprising most of the remainder. It is surprisingly dynamic with various processes driving changes in the distribution of CO2, dust, haze, clouds and water vapor on global scales in the meteorology of Mars atmosphere [I]. The trace gases and isotopic ratios in the atmosphere offer important but subtle clues as to the origins of the planet's atmosphere, hydrology, geology, and potential for biology. In the search for life on Mars, an important process is the ability of bacteria to metabolize inorganic substrates (H2, CO2 and rock) to derive energy and produce methane as a by-product of anaerobic metabolism. Trace gases have been measured in the Mars atmosphere from Earth, Mars orbit, and from the Mars surface. The concentration of water vapor and various carbon-based trace gases are observed in variable concentrations. Within the past decade multiple groups have reported detection of CH4, with concentrations in the 10's of ppb, using spectroscopic observations from Earth [2]. Passive spectrometers in the mid-infrared (MIR) are restricted to the sunlit side of the planet, generally in the mid latitudes, and have limited spectral and spatial resolution. To accurately map the global distribution and to locate areas of possibly higher concentrations of these gases such as plumes or vents requires an instrument with high sensitivity and fine spatial resolution that also has global coverage and can measure during both day and night. Our development goal is a new MIR lidar capable of measuring, on global scales, with sensitivity, resolution and precision needed to characterize the trace gases and isotopic ratios of the Martian atmosphere. An optical parametric oscillator operating in the MIR is well suited for this instrument. The sufficient wavelength tuning range of the OPO can extend the measurements to other organic molecules, CO2, atmospheric water vapor, clouds, temperature, dust, and aerosols, as well as possibly polar-cap properties. Our OPO-approach may allow a new capability for active remote sensing of the outer planets and moons, where the weaker sunlight further limit passive instruments. Here we report on the OPO development effort for this lidar instrument.

Yu, Anthony W.; Numata,Kenji; Riris, haris; Abshire, James B.; Allan, Graham; Sun, Xiaoli; Krainak, Michael A.

2008-01-01

387

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

388

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

389

Implications of light absorbing organic aerosol - “brown carbon” - on satellite retrievals of atmospheric trace gases  

NASA Astrophysics Data System (ADS)

Satellite instruments like GOME, GOME-2, SCIAMACHY and OMI, measure backscattered solar radiation to retrieve atmospheric trace gas columns. In order to quantify these columns, Radiative Transfer (RT) computations of Air Mass Factors (AMFs) are needed to account for radiation scattering and absorption processes. Any RT modeling requires a priori information on the state of the atmosphere such as trace gas/aerosol vertical profiles and aerosol properties (e.g. size parameter and Single Scattering Albedo (SSA)). This a priori input is crucial for the correct quantification of the measured trace gas columns. Recent field studies of urban aerosol show that the Organic Carbon (OC) component contributes highly to the absorption of short wave incoming solar radiation. This leads to measured Single Scattering Albedo (SSA) values as low as 0.78 below 420 nm. Here, the effect of SSA on retrieved AMFs over organic aerosol hotspots, e.g. the urban polluted boundary layer and biomass burning plumes is studied. It is demonstrated that over such hotspots trace gas columns can be underestimated up to a factor of three when neglecting the additional light absorption by OC aerosol. This applies to all trace gases that absorb light at wavelengths shorter than 420 nm, such as HCHO, SO2, BrO, HONO and possibly NO2, if evaluated below 420 nm. The sensitive coupling between trace gas retrievals and OA optical properties that we quantify here also means that any trends in OA optical properties can cause artificial trends in trace gas retrievals; decoupling of both trends requires additional information about the variability of OA optical properties to avoid bias in the long-term trends in trace-gases.

Dix, B. K.; Volkamer, R.

2009-12-01

390

Parallel Computations of Nongray Radiative Heat Transfer  

Microsoft Academic Search

Nongray radiative transfer calculations are demonstrated on parallel computers by spatially decomposing the discrete ordinates method to solve the radiative transport equation (RTE). The predictions from coupling different property models with the RTE are compared against benchmarks for model problems. A validation metric is employed to quantify the agreement with the benchmarks. The weighted-sum-of-gray-gases model, and Patch mean absorption coefficients

Gautham Krishnamoorthy; Rajesh Rawat; Philip J. Smith

2005-01-01

391

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

392

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

393

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

NASA Astrophysics Data System (ADS)

A numerical study is done to understand the possible operating regimes of RF-ICP torch (3 MHz, 50 kW) using different gases for plasma formation at atmospheric pressure. A two dimensional numerical simulation of RF-ICP torch using argon, nitrogen, oxygen, and air as plasma gas has been investigated using computational fluid dynamic (CFD) software fluent©. The operating parameters varied here are central gas flow, sheath gas flow, RF-power dissipated in plasma, and plasma gas. The temperature contours, flow field, axial, and radial velocity profiles were investigated under different operating conditions. The plasma resistance, inductance of the torch, and the heat distribution for various plasma gases have also been investigated. The plasma impedance of ICP torch varies with different operating parameters and plays an important role for RF oscillator design and power coupling. These studies will be useful to decide the design criteria for ICP torches required for different material processing applications.

Punjabi, Sangeeta B.; Joshi, N. K.; Mangalvedekar, H. A.; Lande, B. K.; Das, A. K.; Kothari, D. C.

2012-01-01

394

Electron and ion swarm data of fluorinated gases used in plasma processing  

NASA Astrophysics Data System (ADS)

This paper presents recent data (from 1999-to date) of the theoretical and experimental work that has been done on electron and ion interactions at energies between thermal and 200 eV on the flourinated gases CHF3, CF4, C2F4, C2F6and c-C4F8, and their mixtures with Ar and N2. These gases, used extensively in plasma processing, are currently the subject of intensive research. This review demonstrates that, in spite of the important progress gained in this line of research, many more measurements and refinements to the present theories are needed in order to obtain a complete picture of their interactions with electrons and ions and hence to have reliable and complete data sets with which a more realistic modeling of the gaseous discharges can be made.

de Urquijo, J.

2007-05-01

395

Mechanics of Turbulence of Multicomponent Gases  

Microsoft Academic Search

Turbulence in multicomponent reacting gas mixtures is an important mechanism underlying numerous natural phenomena closely related to the study of our space environment. This book develops a new mathematical approach for modelling multicomponent gas turbulence that adequately describes the combined processes of dynamics and heat and mass transfer when chemical kinetics and turbulent mixing are equally important. The developed models

Mikhail Ya. Marov; Aleksander V. Kolesnichenko

2002-01-01

396

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

397

BIOSIGNATURE GASES IN H?-DOMINATED ATMOSPHERES ON ROCKY EXOPLANETS  

E-print Network

Super-Earth exoplanets are being discovered with increasing frequency and some will be able to retain stable H2-dominated atmospheres. We study biosignature gases on exoplanets with thin H2 atmospheres and habitable surface ...

Seager, Sara

398

CMDL/Carbon Cycle Gases Group Standards Preparation and Stability.  

National Technical Information Service (NTIS)

The NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) Carbon Cycle Gases Group (CCGG) methods and materials for air standards preparation are presented in detail. Atmospheric natural air standards are prepared in aluminum cylinders as reference ga...

D. Kitzis, C. Zhao

1999-01-01

399

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...

400

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

401

Simple Apparatus for Measuring the Critical Properties of Gases  

ERIC Educational Resources Information Center

Describes the construction and operational procedures of a simple setup which enables undergraduate students to conduct experiments on critical phenomena in gases. Indicates that the experimental features are proved comparable to those of the Reamer and Sage apparatus. (CC)

Donaldson, G. B.

1973-01-01

402

An astrophysical view of Earth-based metabolic biosignature gases.  

PubMed

Microbial life on Earth uses a wide range of chemical and energetic resources from diverse habitats. An outcome of this microbial diversity is an extensive and varied list of metabolic byproducts. We review key points of Earth-based microbial metabolism that are useful to the astrophysical search for biosignature gases on exoplanets, including a list of primary and secondary metabolism gas byproducts. Beyond the canonical, unique-to-life biosignature gases on Earth (O(2), O(3), and N(2)O), the list of metabolic byproducts includes gases that might be associated with biosignature gases in appropriate exoplanetary environments. This review aims to serve as a starting point for future astrophysical biosignature gas research. PMID:22269061

Seager, Sara; Schrenk, Matthew; Bains, William

2012-01-01

403

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

404

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

405

40 CFR 86.1314-94 - Analytical gases.  

...respectively, using nitrogen as the diluent. (b) Gases for the hydrocarbon analyzer shall be: (1) Single blends of propane using air as the diluent; and (2) Optionally, for response factor determination, single blends of methanol using...

2014-07-01

406

Low-Value Waste Gases as an Energy Source  

E-print Network

Waste gases with potentially useful fuel value are generated at any number of points in refineries, chemical plants and other industrial and commercial sites. The higher quality streams have been utilized successfully in fuel systems for years...

Waibel, R. T.

407

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

408

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

409

Catalytic destruction of tars in biomass-derived gases  

SciTech Connect

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

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

1988-02-01

410

Non-CO2 greenhouse gases and climate change.  

PubMed

Earth's climate is warming as a result of anthropogenic emissions of greenhouse gases, particularly carbon dioxide (CO(2)) from fossil fuel combustion. Anthropogenic emissions of non-CO(2) greenhouse gases, such as methane, nitrous oxide and ozone-depleting substances (largely from sources other than fossil fuels), also contribute significantly to warming. Some non-CO(2) greenhouse gases have much shorter lifetimes than CO(2), so reducing their emissions offers an additional opportunity to lessen future climate change. Although it is clear that sustainably reducing the warming influence of greenhouse gases will be possible only with substantial cuts in emissions of CO(2), reducing non-CO(2) greenhouse gas emissions would be a relatively quick way of contributing to this goal. PMID:21814274

Montzka, S A; Dlugokencky, E J; Butler, J H

2011-08-01

411

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

412

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

413

Process for treating wastewater which contains sour gases  

US Patent & Trademark Office Database

For the treatment of a wastewater containing sour gases with a stripping gas, resultant stripping gas containing the sour gases is introduced into at least one combustion stage within the total process for recovery of the sulfur-containing components, the wastewater being stripped with at least a portion of the amount of O.sub.2 -containing gas required in the subsequent combustion stages.

1991-07-30

414

Pollutant emissions from ''dirty'' low- and medium-Btu gases  

Microsoft Academic Search

Data were collected to determine the emissions from ''dirty'' low- and medium-Btu gases when combusted on industrial process burners. The fuels utilized were blended to have the composition typically found for Wellman-Galusha oxygen (WGO) and air (WGA) fuel gases. Baseline data were collected for natural gas, ambient WGO and WGA, and hot WGO (700K) and WGA (616K). Then ammonia, hydrogen

R. T. Waibel; E. S. Fleming; D. H. Larson

1979-01-01

415

Membrane Inlet Mass Spectrometry for measuring dissolved gases  

SciTech Connect

A Membrane Inlet Mass Spectrometer (MIMS) is used to measure dissolved gas concentrations in environmental water samples. Gases are exsolved out of water by passing the sample through a silicone gas permeable membrane that is under vacuum. A quadrupole mass spectrometer attached to the vacuum system is capable of measuring a variety of gases over a wide range of concentration. The MIMS is a versatile and field portable instrument.

Singleton, M; Hudson, G

2005-08-10

416

Novel MRI applications of laser-polarized noble gases  

Microsoft Academic Search

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

R. W. Mair; R. L. Walsworth

2002-01-01

417

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

418

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

419

Characterization of lagoon gases by an electronic nose  

E-print Network

CHARACTERIZATION OF LAGOON GASES BY AN ELECTRONIC NOSE A Thesis by JANE CATHERINE WOODCOCK Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE... August 1997 Major Subject: Agricultural Engineering CHARACTERIZATION OF LAGOON GASES BY AN ELECTRONIC NOSE A Thesis by JANE CATHERINE WOODCOCK Submitted to Texas ARM University in partial fulfillment of the requirements for the degree of MASTER...

Woodcock, Jane Catherine

2012-06-07

420

Production of Greenhouse Gases in The Atmosphere of Early Mars  

NASA Technical Reports Server (NTRS)

Mars was much warmer and wetter 3.5 to 4 billion years ago than it is today, suggesting that its climate was able to support life in the distant past. Carbon dioxide and methane are greenhouse gases which may have kept Mars warm during this time. We explore the possibility that these gases were produced via grain-catalyzed reactions in the warm, dusty aftermath of large comet and/or asteroid impacts which delivered Mars, volatile inventory.

Kress, Monika E.; McKay, Christopher P.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

421

Hemoglobin, radiation, morbidity and survival  

SciTech Connect

Analyses concerned with a group of patients treated by radiotherapy for carcinoma of the bronchus give evidence to support the view that oxygen tension at the time of radiation therapy is important both in determining tumor control and radiation morbidity.

Dische, S.; Saunders, M.I.; Warburton, M.F.

1986-08-01

422

Slow-light polaritons in Rydberg gases  

NASA Astrophysics Data System (ADS)

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

Fleischhauer, Michael

2012-02-01

423

Dynamical collision network in granular gases.  

PubMed

We address the problem of recollisions in cooling granular gases. To this aim, we dynamically construct the interaction network in a granular gas, using the sequence of collisions collected in an event driven simulation of inelastic hard disks from time 0 until time t . The network is decomposed into its k -core structure: particles in a core of index k have collided at least k times with other particles in the same core. The difference between cores k+1 and k is the so-called k -shell, and the set of all shells is a complete and nonoverlapping decomposition of the system. Because of energy dissipation, the gas cools down: its initial spatially homogeneous dynamics, characterized by the Haff law, i.e., a t{-2} energy decay, is unstable toward a strongly inhomogeneous phase with clusters and vortices, where energy decays as t{-1} . The clear transition between those two phases appears in the evolution of the k -shells structure in the collision network. In the homogeneous state the k -shell structure evolves as in a growing network with a fixed number of vertices and randomly added links: the shell distribution is strongly peaked around the most populated shell, which has an index k{max} approximately 0.9(d) with (d) the average number of collisions experienced by a particle. During the final nonhomogeneous state a growing fraction of collisions is concentrated in small, almost closed, communities of particles: k{max} is no more linear in (d) and the distribution of shells becomes extremely large developing a power-law tail approximately k{-3} for high shell indexes. We conclude proposing a simple algorithm to build a correlated random network that reproduces, with few essential ingredients, the whole observed phenomenology, including the t{-1} energy decay. It consists of two kinds of collisions (links): single random collisions with any other particle and long chains of recollisions with only previously encountered particles. The algorithm disregards the exact spatial arrangement of clusters, suggesting that the observed stringlike structures are not essential to determine the statistics of recollisions and the energy decay. PMID:17677049

Alvarez-Hamelin, J Ignacio; Puglisi, Andrea

2007-05-01

424

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