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1

EVALUATION OF SIGNIFICANT ANTHROPOGENIC SOURCES OF RADIATIVELY IMPORTANT TRACE GASES  

EPA Science Inventory

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

2

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

Microsoft Academic Search

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

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

2000-01-01

3

RADIATION CHEMISTRY: GASES  

Microsoft Academic Search

A discussion is given of the vsriety of reactions occurring in the ; irradiation of single- and multi-component gaseous systems. The ozonization of ; oxygen is described as an example of one-component gas reactions. In multi-; component systems important reactions involve oxidation, hydrogonation, ; polymerization, reverse reactions, and foreign gases. The use of mass ; spectrometry in the study of

Lind

1961-01-01

4

RADIATION CHEMISTRY OF GASES  

Microsoft Academic Search

Discussions are presented concerning the advantages and limitations of ; gas phase studies in radiation chemistry, observed effects of phase in radiation, ; hot reactions, reactions of thermal I atoms, HCl catalyzed chain isomerizations, ; molecular Hâ detachment, fragmentation of charged species, role of excited ; states, and dissociative electron attachment. (J.R.D.);

1962-01-01

5

RADIATION CHEMISTRY OF GASES  

Microsoft Academic Search

The kinetic radiation equilibrium has only been obtained with two ; systems, nitrogen-oxygen, and carbon dioxide. In the case of the nitrogen--; oxygen system, the end results are nitrogen oxygen, nitrogen dioxide, and nitrous ; oxide, regardless of the initial material. Thus. if nitrous oxide or a 86.33 ; mixture of nitrogen to oxygen is the starting material, the concentrations

P. Harteck; S. Dondes

1958-01-01

6

Radiative heat transfer calculations in real gases  

Microsoft Academic Search

A general formulation for radiative heat transfer calculations is presented, based on integrated quantities such as total emissivities and absorptivities. The procedure is intended particularly for combustion chamber applications of varying degree of complexity, the radiative active medium consisting of gases such as H2O and CO2 and of soot. First, some preliminary calculations are given for the often treated radiative

B. Leckner

1974-01-01

7

Radiative energy transfer in molecular gases  

NASA Technical Reports Server (NTRS)

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

Tiwari, Surendra N.

1992-01-01

8

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

9

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

10

Handbook of infrared radiation from combustion gases  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

11

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

Microsoft Academic Search

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

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

2000-01-01

12

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

13

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

14

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

NASA Technical Reports Server (NTRS)

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

Schoenfeld, Michael

2011-01-01

15

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

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

Radiative heat transfer in a cylindrical mixture of non-gray particulates and molecular gases  

Microsoft Academic Search

The interaction between particulate clouds and molecular gases with respect to radiative heat transfer in a one-dimensional cylindrical medium with black walls is investigated. The particulates are assumed to have a non-gray absorption coefficient with a power-law dependence on wavenumber. The absorption coefficient of the molecular gases is described by the exponential wide-band model. Heat transfer rates are found through

S. Tabanfar; M. F. Modest

1983-01-01

18

Radiative-convective model of warming Mars with artificial greenhouse gases  

Microsoft Academic Search

Artificial greenhouse gases could be used to warm Mars in order to make it habitable. Here we present new laboratory measurements of the thermal infrared absorption spectra of seven artificial greenhouse gases (CF4, C2F6, C3F8, SF6, CF3Cl, CF3Br, CF2Cl2) at concentrations from 10-7 up to unity. We used a radiative-convective multilayer model to compute the warming caused by a mixture

Margarita M. Marinova; Christopher P. McKay; Hirofumi Hashimoto

2005-01-01

19

Radiative-convective model of warming Mars with artificial greenhouse gases  

Microsoft Academic Search

Artificial greenhouse gases could be used to warm Mars in order to make it habitable. Here we present new laboratory measurements of the thermal infrared absorption spectra of seven artificial greenhouse gases (CF4, C2F6, C3F8, SF6, CF3Cl, CF3Br, CF2Cl2) at concentrations from 10?7 up to unity. We used a radiative-convective multilayer model to compute the warming caused by a mixture

Margarita M. Marinova; Christopher P. McKay; Hirofumi Hashimoto

2005-01-01

20

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

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

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

23

Geometric radiation exchange factors for axial radiative transfer in an LWR core filled with absorbing-emitting gases  

SciTech Connect

A reactor core filled with an emitting-absorbing mixture (like steam, hydrogen gas and fission gases) is considered. Analysis is provided to evaluate axial radiative heat exchange of a rod bundle with a nonuniform axial temperature distribution. The necessary radiation exchange shape factors (geometric mean absorptance, emittance and transmittance) between segments of the complex rod bundle arrangement are presented. They are applicable to arbitrary sizes of segments, well suited for numerical computations.

Chan, S.H.; Cho, D.H.

1984-01-01

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

Knudsen cell: Investigations about the uptake of important traces gases on ambient airborne mineral dust  

NASA Astrophysics Data System (ADS)

Mineral dust constitutes one of the largest mass fractions of natural aerosol. Its emission is estimated between 800 - 2000 Tg/a]. The dust is emitted through sand and dust storms in the arid regions of our planet, in particular by the great desserts such as the Sahara. The complex chemical composition of mineral dust is similar to crust material, because the dust is produced by soil erosion. The main components of mineral dust are SiO2 and Al2O3, whereas the active oxides (Fe2O3, TiO2) show some variety in content due to the dust source region. Mineral dust particles can be transported over several 1000 km and during its transport the surface can be changed by the uptake of water vapor and trace gases. On such modified surfaces homo- and heterogeneous reactions can occur. Trace gas uptakes play an important role in atmospheric chemistry as sinks or sources for several gaseous species. Hence, it is necessary to study these reactions. Among several experimental setups, the Knudsen cell is one of the promising tools to study reactive uptakes from the gas phase and the release of products formed by dust surface-mediated reactions. The Knudsen cell, implemented by Golden et al. in 1975, is a high vacuum flow reactor operating under molecular flow conditions, i.e., gas-wall collisions are highly preferred over gas-gas collisions. Despite several Knudsen cell studies examining the reaction between different traces gases and model dust surfaces constituted of not more than a few components, no measurements utilizing collected ambient mineral dust are done so far. For a better understanding of the chemistry on mineral dust surfaces gas uptake measurements will be done with a Knudsen cell. The first measurements are done with isopropanol on TiO2. Afterwards there are studies with different substrates like, Al2O3 (?- and ?-phase), FeO2, Arizona test dust, air collected mineral dust from the Cap Verde islands. In the beginning SO2, NO2 and HNO3 will be used.

Horn, Sabrina; Herrmann, Hartmut

2013-04-01

26

Generation of broadly tunable, narrow bandwidth, and intense coherent vacuum ultraviolet radiation in rare gases  

SciTech Connect

Generation of broadly tunable, narrow bandwidth, and intense coherent vacuum (VUV) radiation in rare gases was investigated using third-order sum-difference frequency mixing processes. VUV radiation in the region between 1180 A and 1240 A was efficiently generated by a resonance enhanced mixing process, [omega][sub VUV] = 2[omega][sub UV] - [omega][sub IR] with near and on the two-photon resonant intermediate states in rare gases, and by phase matching enhancement with gases of oppositely dispersive properties. The input tunable ultraviolet (UV) radiation at frequency [omega][sub UV] was produced by a tunable pulsed dye laser pumped by the second harmonic of a Nd:YAG laser. In one scheme, the dye laser radiation near 5440 A was doubled to 2720 A, and then mixed with the YAG fundamental at 1.06 microns to yield the UV radiation at 2167 A Kr4p(exp 6) yields 4p(exp 5)5p(5/2,2) two-photon resonance wavelength. In another scheme, the tunable UV radiation near 2150 A was obtained by two successive doubling of the dye laser radiation near 8600 A. The input infrared (IR) at frequency [omega][sub IR] was chosen from either the dye laser radiation or the YAG fundamental radiation. The generation system presented here was constructed with the capability of accurately monitoring the wavelength, linewidth, and intensity of generated VUV radiation, and was suitable for high resolution spectroscopic applications. Also of great practical interest, radiation of 1202.8 A (helium 1s(exp 2) + 2h(nu) yields 1s2s[sup S-1] transition), and 1215.6 A (hydrogen 1s + h(nu) yields 2p Lyman-alpha) was included in the generation region and studied by using different schemes. UV to VUV power conversion efficiencies as high as 2 x 10(exp -3) for resonant case, and 4 x 10(exp -4) for non-resonant case were achieved.

Xiong, Xiaoxiong.

1991-01-01

27

A fictitious-gas-based absorption distribution function global model for radiative transfer in hot gases.  

NASA Astrophysics Data System (ADS)

The absorption distribution function model with fictitious gases (ADFFG), a new global model of gas radiative properties, is presented and implemented for CO2 and H2O radiation at atmospheric pressure and in the temperature range (300-2000 K). The model is based on the joint distribution function of the absorption coefficients of two fictitious gases corresponding to hot and cold lines of a given species. Model parameters are deduced from line-by-line (LBL) calculations founded on the EM2C spectroscopic databases. The accuracy of ADFFG is studied, for nonisothermal and nonhomogeneous columns representative of engineering applications, by comparisons with reference LBL calculations and results of the CK and CKFG narrow-band models. It is shown that the subdivision into two fictitious gases significantly enhances the accuracy of ADF (the same model without subdivision), in particular when gaseous absorption is significant, at the cost of larger computing times. Like all global models, ADFFG is, however, limited to applications where walls and particles are gray.

Pierrot, L.; Riviere, P.; Soufiani, A.; Taine, J.

1999-07-01

28

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

29

Experimental study of z-pinch driven radiative shocks in low density gases  

NASA Astrophysics Data System (ADS)

Results of experiments performed on MAGPIE pulsed power facility (1.4MA, 250ns) will be presented. Shocks with velocities of 50-70km/s are driven in Ar, Xe and He gases at density ˜10-5g/cc using radial foil z-pinch configuration [1]. Measurements of the structure of the shocks obtained with laser probing will be presented and observations of the development of instabilities will be discussed. It was found that the structure of the shocks and the development of instabilities strongly depend on the rate of radiative cooling, increasing for gases with higher atomic numbers.[4pt] [1] F. Suzuki-Vidal et al., PoP 19, 022708 (2012)

Skidmore, Jonathan; Lebedev, S. V.; Suzuki-Vidal, F.; Swadling, G.; Bland, S. N.; Burdiak, G.; Chittenden, J. P.; de Grouchy, P.; Hall, G. N.; Pickworth, L.; Suttle, L.; Bennett, M.; Ciardi, A.

2012-10-01

30

Radiative-convective model of warming Mars with artificial greenhouse gases  

NASA Astrophysics Data System (ADS)

Artificial greenhouse gases could be used to warm Mars in order to make it habitable. Here we present new laboratory measurements of the thermal infrared absorption spectra of seven artificial greenhouse gases (CF4, C2F6, C3F8, SF6, CF3Cl, CF3Br, CF2Cl2) at concentrations from 10-7 up to unity. We used a radiative-convective multilayer model to compute the warming caused by a mixture of the four fluorine-based greenhouse gases. The results show that for current Mars, C3F8 produces the largest warming: 0.56 K and 33.5 K for partial pressures of 10-3 Pa and 1 Pa, respectively. Averaged over partial pressures from 0.01 to 1 Pa, the range of most interest for planetary ecosynthesis, CF4, C2F6, and SF6 were 17%, 49%, and 48% as effective as C3F8, respectively. The optimal mixture of the four fluorine-based greenhouse gases, taking into account the overlapping of their absorption bands, was 16% more effective than pure C3F8, averaged over the range 0.01 Pa to 1 Pa. Energy balance calculations suggest that the addition of ~0.2 Pa of the best greenhouse gases mixture or ~0.4 Pa of C3F8 would shift the equilibrium to the extent that CO2 would no longer be stable at the Martian poles and a runaway greenhouse effect would result.

Marinova, Margarita M.; McKay, Christopher P.; Hashimoto, Hirofumi

2005-03-01

31

Study of multi-dimensional radiative energy transfer in molecular gases  

NASA Technical Reports Server (NTRS)

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

Liu, Jiwen; Tiwari, S. N.

1993-01-01

32

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

33

Differential total absorptivity solution to the radiative transfer equation for mixtures of combustion gases and soot  

SciTech Connect

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 considered such that the total radiance is not dominated by either the gaseous or soot components. The DTA solution is shown to yield excellent accuracy relative to a narrow-band solution, with a considerable saving in computational cost. Thus, explicit treatment of the source temperature dependence of absorption is successfully demonstrated without the need for spectral integration.

Bressloff, N.W.; Moss, J.B.; Rubini, P.A. [Cranfield Univ. (United Kingdom). School of Mechanical Engineering

1997-01-01

34

Radiative heat transfer in a plane-layer mixture of non-gray particulates and molecular gases  

Microsoft Academic Search

The interaction between particulate clouds and molecular gases with respect to radiative heat transfer in a one-dimensional plane-parallel geometry is investigated. The absorption coefficient of the molecular gases is described by the exponential wide-band model, and heat transfer rates are determined through the evaluation of internal and external slab emissivities of the particulate cloud, and through evaluation of slab band

M. F. Modest

1981-01-01

35

Radiative heat transfer in a plane-layer mixture of non-gray particulates and molecular gases  

Microsoft Academic Search

The interaction between particulate clouds and molecular gases with respect to radiative heat transfer in a one-dimensional, plane-parallel geometry is investigated. The particulates are assumed to have a non-gray absorption coefficient with a power-law dependence on wavenumber. The absorption coefficient of the molecular gases is described by the popular exponential wide-band model. Heat transfer rates are determined through the evaluation

M. F. Modest

1981-01-01

36

The importance of atmospheric chemistry in the calculation of radiative forcing on the climate system  

SciTech Connect

An interactive two-dimensional model of the troposphere, stratosphere, and mesosphere, in which dynamics, radiation, and chemistry are treated interactively, is used to investigate the anthropogenic changes in the steady state chemical composition of the atmosphere since preindustrial times and to assess the associated changes in radiative forcing on climate. The perturbations in the atmospheric oxidation capacity due to anthropogenic emissions of source gases are found to be significant. In the troposphere, an ozone increase of 80-120% at northern midlatitudes and a global decrease of 10-20% in the OH concentration since the preindustrial period are calculated. In the polar lower stratosphere of the southern hemisphere, an ozone depletion since preindustrial times reaching more than 60% during spring is calculated as a result of rapid catalytical destruction of ozone by chlorine radicals in the presence of polar stratospheric clouds. Particular attention is given to the induced changes in radiative forcing. These results stress the potentially important role of chemical feedbacks on climate and indicate that the direct forcing associated with increasing concentrations of greenhouse gases is enhanced by about 30% when these feedbacks are taken into account. On a global average basis, the greenhouse effect of tropospheric ozone represents approximately 17% of the total radiative perturbation. This forcing is characterized by a strong latitudinal dependence, peaking at midlatitudes in the northern hemisphere. The importance of indirect climate forcings by stratospheric ozone (including local cooling of the stratosphere) is confirmed. It is found that the net (solar + infrared) indirect effect of stratospheric ozone changes is to increase the chlorofluorocarbon direct radiative forcing.

Hauglustaine, D.A.; Granier, C.; Brasseur, G.P.; Megie, G. (CNRS (France) National Center for Atmospheric Research, Boulder, CO (United States))

1994-01-01

37

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

38

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

Microsoft Academic Search

The generalized mathematical model has been developed for radiation induced removal of NO and SO2 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 SO2 concentrations, temperature, humidity, absorbed

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

1996-01-01

39

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

40

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

41

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

42

Radiative-convective model of warming Mars with artificial greenhouse gases  

E-print Network

and a runaway greenhouse effect would result. Citation: Marinova, M. M., C. P. McKay, and H. Hashimoto (20052 and H2O, the dominant natural greenhouse gases on the Earth, are not effective absorbers artificial green- house gases being thousands of times more effective than CO2 in greenhouse warming

Kite, Edwin

43

Non-gray radiative convective conductive modeling of a double glass window with a cavity filled with a mixture of absorbing gases  

Microsoft Academic Search

Coupled radiation and natural convection heat transfer occurs in vertical enclosures with walls at different temperatures filled with gas media. In glass window thermal insulation applications in hot climates, infrared absorbing gases appear as an alternative to improve their thermal performance. The thermal modeling of glass windows filled with non-gray absorbing gases is somewhat difficult due to the spectral variation

Kamal A. R. Ismail

2006-01-01

44

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

45

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

46

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

47

Greenhouse Gases  

NSDL National Science Digital Library

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

48

Coaxial radiative and convective heat transfer in gray and nongray gases  

NASA Technical Reports Server (NTRS)

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

Mattick, A. T.

1980-01-01

49

RADIATIVELY IMPORTANT PARAMETERS BEST ESTIMATE (RIPBE) VALUE-ADDED PRODUCT (VAP)  

E-print Network

Laboratory P.O. Box, Upton, NY www.bnl.gov ABSTRACT Currently, to calculate radiative heating rate profiles for the Broadband Heating Rate Profile (BBHRP) product, radiatively important parameters (water vapor, ozone

50

How important is breathing in radiation therapy of the thorax  

Microsoft Academic Search

Repeated computed tomographic (CT) scanning has been used to assess the effect of quiet breathing on the dosimetry in radiation therapy of the thorax. Density variations as great as 80 CT numbers (8% of the density of water) have been observed between the inspiration and expiration limits of quiet breathing, and movement of anatomical points of greater than 1 cm

R. Mark Henkelman; Katherine Mah

1982-01-01

51

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

52

Directionality of terahertz radiation emitted from an array of femtosecond filaments in gases  

NASA Astrophysics Data System (ADS)

An array of filaments in air is numerically shown to be an efficient tool to direct the energy of terahertz (THz) radiation into a narrow and controllable cone. By increasing the number of filaments in an N × N array, the THz energy growth per unit angle of the cone exceeds the classical gain in N2. The backwardly directed radiation from the filament array appears when the transverse size of the array reaches the filament length. The optimum spacing between the filaments in the array is the THz wavelength, which ensures constructive interference and independent development of filaments.

Panov, N.; Andreeva, V.; Kosareva, O.; Shkurinov, A.; Makarov, V. A.; Bergé, L.; Chin, S. L.

2014-12-01

53

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

PubMed

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

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

2012-02-01

54

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

55

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

56

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

57

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

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

Trends in source gases  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

61

NOBLE GASES  

EPA Science Inventory

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

62

Greenhouse Gases  

MedlinePLUS

... CFCs CO Additional Information Introduction What are greenhouse gases? Many chemical compounds present in Earth's atmosphere behave ... a greenhouse gas. Carbon Monoxide and other reactive gases Carbon monoxide (CO) is not considered a direct ...

63

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

64

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

65

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

66

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

67

Electronegative gases  

SciTech Connect

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

Christophorou, L.G.

1981-01-01

68

A Comparative Study of Modeling of Radiative Heat Transfer using MOL Solution of DOM with Gray Gas, Wide-Band Correlated-k, and Spectral Line-Based Weighted Sum of Gray Gases Models  

Microsoft Academic Search

A radiation code based on the method of lines (MOL) solution of the discrete ordinates method (DOM) for the prediction of radiative heat transfer in nongray absorbing-emitting media was developed by incorporation of two different gas spectral radiative property models, wide-band correlated-k (WBCK) and spectral line-based weighted sum of gray gases (SLW) models. Predictive accuracy and computational efficiency of the

Fatma Nihan Çayan; Nevin Selçuk

2007-01-01

69

Blood gases  

MedlinePLUS

Blood gases are a measurement of how much oxygen and carbon dioxide are in your blood. They also determine ... taking a sample of blood from the wrist area. The health care provider will insert a small ...

70

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

71

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

NASA Astrophysics Data System (ADS)

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

Getoff, Nikola

2006-04-01

72

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

ERIC Educational Resources Information Center

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

Eijkelhof, H. M. C.; And Others

1990-01-01

73

Measurement of Selected Organic Trace Gases During TRACE-P  

NASA Technical Reports Server (NTRS)

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

Atlas, Elliot

2004-01-01

74

Thermal efficiency of the principal greenhouse gases  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

75

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

PubMed

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

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

2015-05-15

76

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

77

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

78

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

79

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

80

On the generation of supershort avalanche electron beams and x radiation during nanosecond discharges in dense gases (results and discussion)  

NASA Astrophysics Data System (ADS)

Results of investigations of the generation of subnanosecond runaway electron beams and x radiation in gas diodes at elevated pressures are presented. The energy distributions of runaway electron beams generated in air at atmospheric pressure and the amplitude and duration of beam current pulses downstream of the foil have been measured, and also the mechanism of generation of a runaway electron beam has been analyzed. To record the beam current pulses, a collector which provided ˜50-ps time resolution and a Tektronix TDS6604 real-time oscilloscope were used in the experiment. It has been shown that the new experimental data and model predictions confirm in the main the results earlier obtained at the Institute of High Current Electronics of the Russian Academy of Sciences Siberian Division. Evidence is cited that the key statements of L. P. Babich are erroneous.

Tarasenko, V. F.; Rybka, D. B.; Baksht, E. H.; Kostyrya, I. D.; Lomaev, M. I.

2007-09-01

81

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

SciTech Connect

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

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

1980-10-01

82

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

83

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

84

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

85

Intraoperative electron radiation therapy as an important treatment modality in retroperitoneal sarcoma  

PubMed Central

Background Local recurrence (LR) rates in patients with retroperitoneal sarcoma (RPS) are high, ranging from 40% to 80%, with no definitive studies describing the best way to administer radiation. Intraoperative electron beam radiation therapy (IOERT) provides a theoretical advantage for access to the tumor bed with reduced toxicity to surrounding structures. The goal of this study was to evaluate the role of IOERT in high-risk patients. Methods An institutional review board approved, single institution sarcoma database was queried to identify patients who received IOERT for treatment of RPS from 2/2001 to 1/2009. Data were analyzed using the Kaplan–Meier method, Cox regression, and Fisher Exact tests. Results Eighteen patients (median age 51 y, 25–76 y) underwent tumor resection with IOERT (median dose 1250 cGy) for primary (n = 13) and recurrent (n = 5) RPS. Seventeen patients received neoadjuvant radiotherapy. Eight high-grade and 10 low-grade tumors were identified. Median tumor size was 15 cm. Four patients died and two in the perioperative period. Median follow-up of survivors was 3.6 y. Five patients (31%) developed an LR in the irradiated field. Three patients with primary disease (25%) and two (50%) with recurrent disease developed an LR (P = 0.5). Four patients with high-grade tumors (57%) and one with a low-grade tumor (11%) developed an LR (P = 0.1). The 2- and 5-y OS rates were 100% and 72%. Two- and 5-y LR rates were 13% and 36%. Conclusions Using a multidisciplinary approach, we have achieved low LR rates in our high-risk patient population indicating that IOERT may play an important role in managing these patients. PMID:23769633

Sweeting, Raeshell S.; Deal, Allison M.; Llaguna, Omar H.; Bednarski, Brian K.; Meyers, Michael O.; Yeh, Jen Jen; Calvo, Benjamin F.; Tepper, Joel E.; Kim, Hong Jin

2014-01-01

86

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

SciTech Connect

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

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

1993-12-01

87

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

88

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

89

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

SciTech Connect

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

Clough, S.A.

1993-11-15

90

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

SciTech Connect

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

Bentzen, Soren M., E-mail: bentzen@humonc.wisc.ed [Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI (United States); Radiation Therapy Oncology Group, Philadelphia, PA (United States); Parliament, Matthew [Cross Cancer Institute and University of Alberta, Edmonton, Alberta (Canada); Deasy, Joseph O. [Mallinckrodt Institute of Radiology, Washington University Medical Center, St. Louis, MO (United States); Dicker, Adam [Radiation Therapy Oncology Group, Philadelphia, PA (United States); Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA (United States); Curran, Walter J. [Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA (United States); Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA (United States); Williams, Jacqueline P. [University of Rochester Medical Center, Rochester, NY (United States); Rosenstein, Barry S. [Department of Radiation Oncology, Mount Sinai School of Medicine and NYU School of Medicine, New York, NY (United States)

2010-03-01

91

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

92

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

93

Conidial pigmentation is important to tolerance against solar-simulated radiation in the entomopathogenic fungus Metarhizium anisopliae.  

PubMed

The importance of conidial pigmentation to solar UV radiation tolerance in the entomopathogenic fungus Metarhizium anisopliae var. anisopliae, was estimated by comparing the effects of exposure to simulated solar UV radiation on the wild-type parent strain U.S. Department of Agriculture (USDA)-Agricultural Research Service (ARS) Collection of Entomopathogenic Fungal Cultures (ARSEF) 23, which has dark green conidia, and three groups of color mutants with yellow, purple and white conidia. The comparisons included inactivation levels and the kinetics of germination of conidia exposed or not exposed to simulated solar UV radiation. In addition to significantly inactivating the conidia of different mutants, exposure to radiation delayed for several hours the germination of surviving conidia of the wild type and all mutants. In general, mutants with white conidia were more sensitive to simulated solar UV radiation than mutants with purple conidia, which were more sensitive than mutants with yellow conidia, which in turn were more sensitive than the green wild strain. A significant variation in tolerance to simulated solar radiation was observed among mutants within each color group, particularly among mutants with yellow conidia. Revertants with green conidia, DWR 179 and DWR 176, were obtained from the very sensitive UV mutants DWR 148 (yellow conidia) and DWR 149 (purple conidia), respectively. These revertants had levels of tolerance to simulated solar UV radiation similar to those of the wild-type ARSEF 23. This observation is strong evidence of the importance of green conidial pigmentation for tolerance to simulated solar UV radiation, a factor that could be manipulated to produce M. anisopliae strains with more tolerance to solar UV radiation. PMID:16613494

Braga, Gilberto U L; Rangel, Drauzio E N; Flint, Stephan D; Anderson, Anne J; Roberts, Donald W

2006-01-01

94

Greenhouse Gases  

NSDL National Science Digital Library

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

2012-07-19

95

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

Microsoft Academic Search

Halogenated trace gases play an important role in stratospheric and tropospheric chemistry, particularly affecting ozone concentrations. In addition they have direct and indirect effects on radiative forcing, and impact on tropospheric reactivity. Data from the CARIBIC project (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrumented Container) have been used in conjunction with back-trajectory analysis to further

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

2007-01-01

96

Solids Liquids and Gases  

NSDL National Science Digital Library

Compare and contrast the three states of matter: solids, liquids and gases. First you will begin by looking at characteristics of each solids, liquids and gasesGases, Liquids and Solids Facts. Then you will look at examples of each stateSolids, Liquids and Gases Video. Demonstrate an understanding of solids, liquids and gases by playing interactive gameSolids, Liquids and Gases Game. Graphic Organizer is here to be filled out as you learn during this lesson. Use the red ...

Ms. Salter

2009-10-22

97

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

Microsoft Academic Search

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

C. A. Wilson

98

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

E-print Network

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

California at Santa Cruz, University of

99

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

100

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

E-print Network

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

Weihsueh A. Chiu; B. T. Draine

1998-03-18

101

Determination of Important Nuclear Fragmentation Processes for Human Space Radiation Protection  

NASA Technical Reports Server (NTRS)

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

Lin, Zi-Wei

2007-01-01

102

Thermodynamic models of the chemistry of lunar volcanic gases  

Microsoft Academic Search

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

1991-01-01

103

Thermodynamic models of the chemistry of lunar volcanic gases  

Microsoft Academic Search

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

Bruce Fegley Jr.

1991-01-01

104

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

105

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

Microsoft Academic Search

Continuous atmospheric measurements were carried out at the Pico de Orizaba National Park (PONP), Mexico, in order to evaluate the characteristics and sources of air quality. This action allowed one to identify specific threats for the effective protection of natural resources and biodiversity. Results show the presence of particles and polluted gases transported by winds from the urban zones nearby

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

2005-01-01

106

On the Importance of Prompt Oxygen Changes for Hypofractionated Radiation Treatments  

PubMed Central

This discussion is motivated by observations of prompt oxygen changes occurring prior to 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. PMID:24061351

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

2013-01-01

107

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

108

Inorganic fluorescent screen properties important for MeV radiation imagery  

Microsoft Academic Search

This report summarizes observed properties of inorganic fluorescent screens that are important in imaging experiments that rely on MeV photons and neutrons. The summary is based on our earlier, more comprehensive report. Recent, preliminary results of Monte Carlo calculations that complement that work are also discussed.

G. J. Berzins; A. H. Lumpkin; H. L. Smith

1984-01-01

109

Conduction of Electricity in Gases  

Microsoft Academic Search

The conduction of electricity through gases has played ubiquitous roles in science and technology. It was responsible for many of the fundamental discoveries in atomic and molecular physics; gas discharge lighting is essential to every night operations; gas discharge lasers are still important in research and manufacturing; and all of advanced microelectronics depends on plasma enhanced processing. To a large

Alan Garscadden

2006-01-01

110

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

111

Electrical breakdown of gases  

Microsoft Academic Search

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

J. M. Meek; J. D. Craggs

1978-01-01

112

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

SciTech Connect

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

Ward, J.F.

1994-03-01

113

Emissions of biogenic sulfur gases from northern bogs and fens  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

114

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

115

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

EPA Science Inventory

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

116

New Thermospheric Infrared Radiative Flux and Power Results From the SABER Experiment  

Microsoft Academic Search

The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite measures the vertical distribution of infrared radiation emitted by various atmospheric gases (ozone, water vapor, nitric oxide, and carbon dioxide), providing important information about the radiation budget in the upper atmosphere. From these measurements, the infrared power and energy radiated by

L. A. Hunt; M. G. Mlynczak; F. J. Martin-Torres; C. J. Mertens; B. T. Marshall; J. M. Russell; L. L. Gordley

2008-01-01

117

Radiative association rate constant for the formation of CO: the importance of the first excited 1?+ state  

NASA Astrophysics Data System (ADS)

The thermal rate constant for production of carbon monoxide, in its electronic ground state, through radiative association of carbon (C) and oxygen (O) atoms is computed. A combination of quantum and classical dynamics methods are employed. In particular, we investigate the importance of the mechanism where C and O approach each other on the 21?+ potential energy curve. Accounting for this reaction turns out to add about 75 per cent to the rate constant at 10 000 K. We expect the results to be important for studies of the chemistry in interstellar gas, particularly in metal-rich ejecta of supernovae. Since a significant isotope effect has been predicted previously both stable carbon isotopes 12C and 13C are considered in the present study.

Gustafsson, Magnus; Nyman, Gunnar

2015-04-01

118

Climate-chemical interactions and greenhouse effects of trace gases  

NASA Technical Reports Server (NTRS)

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

Shi, Guang-Yu; Fan, Xiao-Biao

1994-01-01

119

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

120

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

PubMed Central

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

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

2014-01-01

121

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

SciTech Connect

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

Wigley, T.M.L.

1993-01-01

122

Transport of Trace Gases  

NASA Technical Reports Server (NTRS)

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

Schoeberl, Mark R.

2005-01-01

123

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.

Eric Eric Benson

124

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...

125

Measurements of Lyman Alpha Radiation from Collisions, 100 EV to 4000EV, of Negative Hydrogen Ions on Various Target Gases and Positive Hydrogen Ions on Xenon  

Microsoft Academic Search

This study reports measurements of cross sections for the production of Lyman alpha radiation from processes in which an ion is incident on a neutral target gas. Two kinds of processes were measured: the stripping of the extra electron from a negative hydro- gen ion leaving an excited neutral and the capture of an electron by a proton also leaving

Glenn Blair Greenland

1985-01-01

126

Decomposition of greenhouse gases by plasma  

Microsoft Academic Search

The topic of decomposition and reduction of greenhouse gases is becoming an important issue in tackling the global warming\\u000a effect since several years ago. Several technologies, including plasma-utilized process, were proposed to improve the treatment\\u000a ability for the destruction of green house gases usually emitted by industrial activities. In this review paper, the application\\u000a of plasma to reduce the emission

Antonius Indarto; Jae-Wook Choi; Hwaung Lee; Hyung Keun Song

2008-01-01

127

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

128

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

129

Importance of radiation effects in ion-beam-driven inertial fusion target calculations: Compensation of range shortening by radiation transport in ion-beam-generated plasmas  

NASA Astrophysics Data System (ADS)

In this paper computer simulation results showing that radiation can compensate for range shortening in ion-beam inertial fusion targets are presented. Simulation results of ablation, compression, ignition, burn, and hydrodynamic stability of a heavy ion-beam-driven, reactor-size, inertial confinement fusion (ICF) target including radiation transport are also reported. In this target design the fuel is protected against radiative preheat by a high-Z, high-? lead radiation shield, and the fuel is separated from the radiation shield by a low-Z, low-? lithium cushion. This avoids mixing of the lead from the radiation shield into the fuel at the end of the implosion. The target is driven by 10 GeV Bi++ ions, and it yields an output energy of ˜690 MJ for an imput energy of ˜4.56 MJ, so that the overall target gain is ˜152. The peak power in the input pulse is 500 TW.

Tahir, N. A.; Long, K. A.

1986-04-01

130

Importance of radiation effects in ion-beam-driven inertial fusion target calculations: Compensation of range shortening by radiation transport in ion-beam-generated plasmas  

Microsoft Academic Search

In this paper computer simulation results showing that radiation can compensate for range shortening in ion-beam inertial fusion targets are presented. Simulation results of ablation, compression, ignition, burn, and hydrodynamic stability of a heavy ion-beam-driven, reactor-size, inertial confinement fusion (ICF) target including radiation transport are also reported. In this target design the fuel is protected against radiative preheat by a

N. A. Tahir; K. A. Long

1986-01-01

131

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

PubMed

A new technique has been developed to make possible the laboratory study of the infrared-emission spectra of gases of atmospheric interest. The thermal-emission spectra are in local thermodynamic equilibrium, just as they are in the atmosphere, and are not chemiluminescent. Demonstration results obtained by the use of this new technique are presented for dichlorodifluoromethane (CFC-12) at a pressure of 0.5 Torr in a cell with a path length of 5 cm. The measured cell spectra have been compared with simulations with the FASCD3P radiation code. The measurements of the emission spectra of radiatively active gases may be important for the atmospheric greenhouse effect and global warming. PMID:21085268

Evans, W F; Puckrin, E

1996-03-20

132

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

133

Strongly interacting Fermi gases  

E-print Network

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

Bakr, W.

134

Photochemistry of biogenic gases  

NASA Technical Reports Server (NTRS)

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

Levine, Joel S.

1989-01-01

135

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

2015-04-01

136

High-temperature properties of gases  

NASA Technical Reports Server (NTRS)

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

Cooper, David M.

1991-01-01

137

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

138

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

SciTech Connect

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

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

2010-03-01

139

Carbon uptake in a marine diatom during acute exposure to ultraviolet B radiation: Relative importance of damage and repair  

SciTech Connect

Experiments on a marine diatom, Thalassiosira pseudonana (Hustedt) clone 3H, demonstrate that under moderate photon flux densities (75 [mu]mol quanta [center dot] m[sup [minus]2][center dot]s[sup [minus]1]) of visible light inhibition of photosynthesis by supplemental ultraviolet (UV) radiation (UV-B: 280-320 nm) is well described as a hyperbolic function of UV-B irradiance for time scales of 0.5-4 h. Results are consistent with predictions of a recently developed model of photosynthesis under the influence of UV and visible irradiance. Although net destruction of chlorophyll occurs during a 4-h exposure to UV-B, and the effect is a function of exposure, the principal effect of UV-B is a decrease in chlorophyll-specific photosynthetic rate. The dependence of photoinhibition on dosage rate, rather than cumulative dose, and the hyperbolic shape of the relationship are consistent with net photoinhibition being an equilibrium between damage and repair. The ratio of damage to repair is estimated by a mathematical analysis of the inhibition of photosynthesis during exposures to UV-B. A nitrate-limited culture was much more sensitive to UV-B than were the nutrient-replete cultures, but the kinetics of photoinhibition were similar. The analysis suggests that the nutrient-limited culture was much more sensitive than the nutrient-replete cultures because repair or turnover of critical proteins associated with photosynthesis is inhibited. An inhibitor of chloroplast protein synthesis was used to suppress repair processes. Photoinhibition by UV-B was enhanced, and inhibition was a function of cumulative dose, as expected if damage were not countered by repair. The fundamental importance of repair processes should be considered in the design of field experiments and models of UV-B effects in the environment, especially in the context of vertical mixing. Repair processes must also be considered whenever biological weighting functions are developed. 69 refs., 6 figs., 3 tabs.

Lesser, M. P. (Bigelow Lab. for Ocean Sciences, West Boothbay Harbor, ME (United States)); Cullen, J.J. (Bigelow Lab. for Ocean Sciences, West Boothbay Harbor, ME (United States) Dalhousie Univ., Halifax, Nova Scotia (Canada)); Neale, P.J. (Bigelow Lab. for Ocean Sciences, West Boothbay Harbor, ME (United States) Univ. of California, Berkeley, CA (United States))

1994-04-01

140

Deviation from the Knudsen law on quantum gases  

NASA Astrophysics Data System (ADS)

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

Babac, Gulru

2014-12-01

141

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

E-print Network

The search for particle electric dipole moments represents a most promising way to search for physics beyond the standard model. A number of groups are planning a new generation of experiments using stored gases of various kinds. In order to achieve the target sensitivities it will be necessary to deal with the systematic error resulting from the interaction of the well-known E x v field with magnetic field gradients (often referred to as the geometric phase effect [9,10]). This interaction produces a frequency shift linear in the electric field, mimicking an edm. In this work we introduce an analytic model for the correlation function which determines the behavior of the frequency shift [11], and show in detail how it depends on the operating conditions of the experiment. We also propose a method to directly measure ths correlation function under the exact conditions of a given experiment.

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

2005-12-20

142

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

143

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

PubMed

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

Tomita, Masanori; Maeda, Munetoshi

2014-10-31

144

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

PubMed Central

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

Tomita, Masanori; Maeda, Munetoshi

2015-01-01

145

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.

146

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,

147

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

148

Gases in Tektite Bubbles.  

PubMed

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

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

1962-07-20

149

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

150

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

NASA Astrophysics Data System (ADS)

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

Zadorozhny, Alexander; Dyominov, Igor

151

Analysis of gases in Mississippi Valley-type ore fluids  

Microsoft Academic Search

Volatiles in fluid inclusions in ore and gangue minerals from Mississippi Valley-type deposits in Missouri, Arkansas, and Kansas have been analyzed by mass spectrometry, gas chromatography, and laser Raman spectroscopy. The application of these techniques together with detailed fluid inclusion petrography is a powerful approach to characterization of gases in fluid inclusions. The most important gases determined were COâ, Nâ,

D. L. Leach; G. P. Landis; J. S. Leventhal; A. H. Hofstra

1985-01-01

152

16 Rangelands educing concentrations of greenhouse gases  

E-print Network

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

153

The Environmental Chemistry of Trace Atmospheric Gases  

Microsoft Academic Search

The atmospheric importance of carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons is discussed. Atmospheric concentrations of these species have increased because of human activities. Sources, lifetimes, atmospheric budgets, and global warming potentials are presented for the key trace gases. Nitrous oxide, a recently discovered industrial emission byproduct, is examined for its role in stratospheric ozone chemistry and global warming. The

William C. Trogler

1995-01-01

154

Guidance Document CompressedGases  

E-print Network

, oxygen and other oxidizing gases. Flammable gases can be ignited by heat, flame, hot object or static electricity. Oxygen by itself does not burn, but it will support or accelerate combustion of flammable

155

EFFECTS OF INCREASED SOLAR ULTRAVIOLET RADIATION ON BIOGEOCHEMICAL CYCLES  

EPA Science Inventory

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

156

Carbon uptake in a marine diatom during acute exposure to ultraviolet B radiation: Relative importance of damage and repair  

Microsoft Academic Search

Experiments on a marine diatom, Thalassiosira pseudonana (Hustedt) clone 3H, demonstrate that under moderate photon flux densities (75 [mu]mol quanta [center dot] m[sup [minus]2][center dot]s[sup [minus]1]) of visible light inhibition of photosynthesis by supplemental ultraviolet (UV) radiation (UV-B: 280-320 nm) is well described as a hyperbolic function of UV-B irradiance for time scales of 0.5-4 h. Results are consistent with

Michael P. Lesser; John J. Cullen; Patrick J. Neale

1994-01-01

157

The Chemistry of Biological Gases  

Microsoft Academic Search

\\u000a Today there are at least four biological gases: oxygen (O2), nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide\\u000a (H2S). Except for molecular oxygen, many of these gases were originally known for their detrimental physiological effects.\\u000a However, the current consensus suggests that these gases play a role in signal transduction, modulating physiological function.\\u000a The roles of these gases are complex

D. Jeannean Carver; Lisa A. Palmer

158

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

159

Advanced Global Atmospheric Gases Experiment (AGAGE)  

NASA Technical Reports Server (NTRS)

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

Prinn, Ronald G.

2001-01-01

160

Kinetic Theory of Gases  

NASA Astrophysics Data System (ADS)

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

Murdin, P.

2000-11-01

161

Sudden releases of gases  

NASA Astrophysics Data System (ADS)

Conurbations all over the world have enlarged for numberless years. The accidental or intentional releases of gases become more frequent. Therefore, these crises situations have to be studied. The aim of this paper is to describe experiments examining these processes that were carried out in the laboratory of Environmental Aerodynamics of the Institute of Thermomechanics AS CR in Nový Knín. Results show huge puff variability from replica to replica.

Chaloupecká, Hana; Ja?our, Zbyn?k; Jur?áková, Klára; Kuka?ka, Libor; Nosek, Št?pán

2014-03-01

162

Greenhouse Gases Exposed  

NSDL National Science Digital Library

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

Victoria Babcock

163

SN52, a novel nuclear factor-kappaB inhibitor, blocks nuclear import of RelB:p52 dimer and sensitizes prostate cancer cells to ionizing radiation.  

PubMed

The activation of nuclear factor-kappaB (NF-kappaB) is thought to protect cancer cells against therapy-induced cytotoxicity. RelB, a member of the NF-kappaB family in the alternative pathway, is uniquely expressed at a high level in prostate cancer with high Gleason scores. Here, we show that ionizing radiation (IR) enhances nuclear import of RelB, leading to up-regulation of its target gene, manganese superoxide dismutase (MnSOD), and renders prostate cancer cells resistant to IR. To selectively block RelB nuclear import, we designed a cell-permeable SN52 peptide, a variant of the SN50 peptide that has been shown to block nuclear import of NF-kappaB family members in the classic pathway. Inhibition of IR-induced NF-kappaB activation by SN50 and SN52 was achieved by selectively interrupting the association of p50 and p52 with nuclear import factors importin-alpha1 and importin-beta1. Importantly, SN52 seems to be more efficient for radiosensitization of prostate cancer cells at clinically relevant radiation doses and has less cytotoxicity to normal prostate epithelial cells compared with the toxicity observed with SN50. These results suggest that targeting the alternative pathway is a promising approach to selectively radiosensitize prostate cancers and that SN52 may serve as a prototype biological agent for sensitizing prostate cancers to clinically relevant doses of IR. PMID:18723484

Xu, Yong; Fang, Fang; St Clair, Daret K; Sompol, Pradoldej; Josson, Sajni; St Clair, William H

2008-08-01

164

Greenhouse gases: What is their role in climate change  

SciTech Connect

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

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

1990-12-01

165

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

NASA Astrophysics Data System (ADS)

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

Girard, Eric; Sokhandan Asl, Niloofar

2014-01-01

166

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

167

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

168

NMR studies and applications of perfluorocarbon gases  

NASA Astrophysics Data System (ADS)

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

Chang, Yulin

169

Chemical reactions of mercury in combustion flue gases  

Microsoft Academic Search

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

B. Hall; P. Schager; O. Lindqvist

1991-01-01

170

(Desulfurization of fuel gases)  

SciTech Connect

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

Not Available

1991-12-15

171

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

SciTech Connect

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

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

2008-12-01

172

Measurement of fission product gases in the atmosphere  

NASA Astrophysics Data System (ADS)

The ability to quickly detect and assess the magnitude of releases of fission-produced radioactive material is of significant importance for ongoing operations of any conventional nuclear power plant or other activities with a potential for fission product release. In most instances, the control limits for the release of airborne radioactivity are low enough to preclude direct air sampling as a means of detection, especially for fission gases that decay by beta or electron emission. It is, therefore, customary to concentrate the major gaseous fission products (krypton, xenon and iodine) by cryogenic adsorption for subsequent separation and measurement. This study summarizes our initial efforts to develop an automated portable system for on-line separation and concentration with the potential for measuring environmental levels of radioactive gases, including 85Kr, 131,133,135Xe, 14C, 3H, 35S, 125,131I, etc., without using cryogenic fluids. Bench top and prototype models were constructed using the principle of heatless fractionation of the gases in a pressure swing system. This method removes the requirement for cryogenic fluids to concentrate gases and, with suitable electron and gamma ray detectors, provides for remote use under automatic computer control. Early results using 133Xe tracer show that kinetic chromatography, i.e., high pressure adsorption of xenon and low pressure desorption of air, using specific types of molecular sieves, permits the separation and quantification of xenon isotopes from large volume air samples. We are now developing the ability to measure the presence and amounts of fission-produced xenon isotopes that decay by internal conversion electrons and beta radiation with short half-lives, namely 131mXe, 11.8 d, 133mXe, 2.2 d, 133Xe, 5.2 d and 135Xe, 9.1 h. The ratio of the isotopic concentrations measured can be used to determine unequivocally the amount of fission gas and time of release of an air parcel many kilometers downwind from a nuclear activity where the fission products were discharged.

Schell, W. R.; Tobin, M. J.; Marsan, D. J.; Schell, C. W.; Vives-Batlle, J.; Yoon, S. R.

1997-01-01

173

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

174

Radiation dosimetry.  

PubMed Central

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

Cameron, J

1991-01-01

175

Advanced Global Atmospheric Gases Experiment (AGAGE)  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

176

Electron beam treatment of stack gases  

NASA Astrophysics Data System (ADS)

A method of simultaneously removing sulfur dioxide and nitrogen oxides from high sulfur, coal-fired utility boiler combustion gases is discussed. Process development history is briefly presented and salient details of a commercial demonstration unit currently under construction at an electric utility power plant in Indiana are given. Detailed discussion on the design details and performance requirements of a cable connected set of 80 kW electron beam sources precedes a discussion of the projected economics of the process. Requirements for future electron beam machine configurations and capacities as well as impact on the radiation machine manufacturing industry, assuming acceptance of the process by the electric utilities, are presented.

Frank, N.; Kawamura, K.; Miller, G.

177

Kinetic Molecular Theory of Gases  

NSDL National Science Digital Library

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

David N. Blauch

178

Greenhouse Gases: A Closer Look  

NSDL National Science Digital Library

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

King's Centre for Visualization in Science

179

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

180

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

181

Megacity Radiative Forcing: A Mexico City Case Study  

NASA Astrophysics Data System (ADS)

We assess the radiative forcing 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 (ozone) to long-term global-scale impacts due to longer-lived trace gases (e.g., carbon dioxide, methane). In this study we combine chemistry-transport model simulations from the Model for Ozone And Related Chemical Tracers (MOZART-2) with in situ and satellite observations from the Aerosol Robotic Network (AERONET) and the Moderate Resolution Imaging Spectroradiometer (MODIS) to calculate the global radiative forcing of megacity emissions. We also explore the radiative impact of various emission control strategies that focus on improving regional air quality. Our results suggest that the warming by greenhouse gases like carbon dioxide 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 the trade-offs between improving local air quality and minimizing global radiative impacts.

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

2007-05-01

182

46 CFR 194.15-17 - Compressed gases other than inert gases.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Compressed gases other than inert gases. 194.15-17 Section 194...AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-17 Compressed gases other than inert gases....

2013-10-01

183

46 CFR 194.15-17 - Compressed gases other than inert gases.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 false Compressed gases other than inert gases. 194.15-17 Section 194...AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-17 Compressed gases other than inert gases....

2014-10-01

184

46 CFR 194.15-17 - Compressed gases other than inert gases.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Compressed gases other than inert gases. 194.15-17 Section 194...AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-17 Compressed gases other than inert gases....

2012-10-01

185

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

186

Greenhouse effect of chlorofluorocarbons and other trace gases  

Microsoft Academic Search

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

James Hansen; Andrew Lacis; Michael Prather

1989-01-01

187

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

188

New spectral features of stratospheric trace gases  

NASA Technical Reports Server (NTRS)

A new Michelson-type interferometer system operating in the infrared at very high resolution (0.002 to 0.003 wavenumber FWHM) was used to record numerous balloon-borne solar absorption spectra of the stratosphere, ground-based solar absorption spectra, and laboratory spectra of molecules of atmospheric interest. Results obtained are reported for several important stratospheric trace gases, HNO3, ClONO2, HO2NO2, NO2, and COF2, in the 8 to 12 micron spectral region. Many features of these gases were identified in the stratospheric spectra. Comparison of the spectra with line-by-line simulations shows previous spectral parameters are often inadequate. New analysis of high resolution laboratory and atmospheric spectra and improved theoretical calculations will be required for all bands. Preliminary versions of several sets of improved line parameters are presented.

Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Kosters, J. J.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.

1990-01-01

189

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

E-print Network

Impacts of greenhouse gases and aerosol direct and indirect effects on clouds and radiation. Besides the direct impact on radiation through the greenhouse effect and scattering of sunlight decreasing the total greenhouse effect in the longwave spectrum and increasing absorption of solar radiation

Dufresne, Jean-Louis

190

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 they’ll do it by heating wood pellets or wood splints in a test tube. They will collect the resulting gases and use the gas to roast a marshmallow. Learners will also evaluate which biomass fuel is the best either according to their own criteria or by examining the volume of gas produced by each type of fuel.

2012-07-03

191

Noble gases in the moon  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

192

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

193

Optical diagnostics of streamer discharges in atmospheric gases  

NASA Astrophysics Data System (ADS)

This paper reviews optical diagnostic methods and approaches applied to study the fundamentals of streamer discharges, considering the peculiarities of streamers developing in atmospheric gases at high (1?bar) as well as low (<10?mbar) pressures. A critical discussion is devoted to the cross-sections for electron-impact excitation/ionization/dissociation processes and corresponding rate constants in relation to methods used to probe streamer properties. The most important spectrometric signatures of radiative transitions of diatomic as well as atomic species are discussed on the basis of their synthetic models with a brief guide on how to simulate the most important emissions. Basic differences between UV–vis–NIR spectra produced by electron-impact and various heavy-particle energy-transfer processes during streamer evolution are presented and possible strategies based on 2D projections of cylindrically symmetric streamers to determine radial distributions of excited species within the streamer channel are discussed. The use of emission techniques to obtain the rotational temperatures and vibrational distributions of excited states of diatomics and laser-induced fluorescence techniques to probe the vibrational manifold of the lowest triplet metastable state of the nitrogen molecule is addressed.

Šimek, M.

2014-11-01

194

Low-dimensional trapped gases  

Microsoft Academic Search

Recent developments in the physics of ultracold gases provide wide possibilities for reducing the dimensionality of space for magnetically or optically trapped atoms. The goal of these lectures is to show that regimes of quantum degeneracy in two-dimensional (2D) and one-dimensional (1D) trapped gases are drastically different from those in three dimensions and to stimulate an interest in low-dimensional systems.

D. S. Petrov D. M. Gangardt G. V. Shlyapnikov; D. M. Gangardt; G. V. Shlyapnikov

2004-01-01

195

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

SciTech Connect

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

Seager, Richard

2014-12-08

196

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

SciTech Connect

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

Shine, K.P. (Univ. of Reading (United Kingdom))

1991-06-15

197

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

SciTech Connect

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

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

2013-09-01

198

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

NASA Technical Reports Server (NTRS)

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

Temim, Tea; Dwek, Eli

2013-01-01

199

High field optical nonlinearities in gases  

NASA Astrophysics Data System (ADS)

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

Cheng, Yu-Hsiang

200

Effects of Solar Radiation on the Optical Quality of Dissolved Organic Material in a Tidal Marsh Estuarine Ecosystem  

Microsoft Academic Search

Photochemical alteration of colored dissolved organic matter (CDOM) during exposure to solar UV and Visible radiation generates a variety of photoproducts, including reactive oxygen species, atmospherically important trace gases, and microbially labile carbonyl compounds. Sunlight-induced changes in CDOM chemical structure are reflected in changes of its optical properties that provide a first order measure of the photoreactivity of CDOM in

M. Tzortziou; P. J. Neale; C. L. Osburn; J. R. Herman

2007-01-01

201

EDITORIAL: Cold Quantum GasesEditorial: Cold Quantum Gases  

NASA Astrophysics Data System (ADS)

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

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

2003-04-01

202

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

203

Abating environmentally harmful waste gases  

NASA Astrophysics Data System (ADS)

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

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

2002-05-01

204

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.

Department of Physics and Astronomy

205

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

206

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

207

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

208

Greenhouse gases and recovery of the Earth's ozone layer  

Microsoft Academic Search

A numerical 2-D zonally averaged dynamical radiative-photochemical model of the ozonosphere including aerosol physics is used to examine the role of the greenhouse gases CO2, CH4, and N2O in the recovery of the Earth's ozone layer after reduction of anthropogenic discharges of chlorine and bromine compounds into the atmosphere. A weakness in efficiencies of all catalytic cycles of the ozone

Igor G. Dyominov; Alexander M. Zadorozhny

2005-01-01

209

Greenhouse gases thinning the thermosphere  

NSDL National Science Digital Library

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

Emmert et al.

210

Feshbach Resonances in Ultracold Gases  

NASA Astrophysics Data System (ADS)

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

Kokkelmans, Servaas

2015-09-01

211

On Classical Gases. Jacques Arnaud  

E-print Network

On Classical Gases. Jacques Arnaud Mas Liron, F30440 Saint Martial, France Laurent Chusseau IES n 5506 au CNRS, 161 rue Ada, F34392 Montpellier, France April 19, 2013 Abstract The ideal gas laws that these laws are independent of the laws of motion aside from the law of energy conservation. A single

Boyer, Edmond

212

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

213

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

214

The toxicological properties of petroleum gases.  

PubMed

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

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

2014-01-01

215

Rare gases systematics and mantle structure  

NASA Technical Reports Server (NTRS)

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

Allegre, C. J.; Staudacher, T.

1994-01-01

216

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 in polymers is a fun- damental concern in such areas as food packaging, beverage storage, and polymer pro

Magee, Joseph W.

217

75 FR 14081 - Mandatory Reporting of Greenhouse Gases: Minor Harmonizing Changes to the General Provisions  

Federal Register 2010, 2011, 2012, 2013, 2014

...management systems with combined CH4 amd N2O emissions in amounts equivalent to 25...greenhouse gases with annual bulk imports of N2O, fluorinated GHG, and CO2 that in combination...greenhouse gases with annual bulk exports of N2O, fluorinated GHG, and CO2 that in...

2010-03-24

218

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 contribution to the debate on environmental policy in Denmark. #12;3 Contents 1 SUMMARY 5 1.1 OZONE OZONE-DEPLETING SUBSTANCES 19 3.1 IMPORTS AND EXPORTS 19 3.1.1 CFCs 19 3.1.2 Tetrachloromethane 19 3

219

Chemistry of Carbon Gases in Volcanic Gases on Io  

Microsoft Academic Search

We use chemical equilibrium calculations to model the chemistry of carbon in volcanic gases on Io (Schaefer and Fegley 2004, ApJ, in review). The calculations covered temperatures from 500 - 2000 K, pressures from 10-8 to 10+2 bars, and bulk O\\/S atomic ratios from ˜ 0 to 3. These conditions overlap the nominal conditions at Pele, where T = 1760

L. Schaefer; B. Fegley Jr.

2004-01-01

220

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

221

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

SciTech Connect

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

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

1995-12-31

222

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

223

Emissions of greenhouse gases in the United States 1997  

SciTech Connect

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

NONE

1998-10-01

224

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

225

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

226

Radiative forcing calculations for CH3Cl and CH3Br  

NASA Astrophysics Data System (ADS)

Methyl chloride, CH3Cl, and methyl bromide, CH3Br, are particularly important in the global atmosphere as major natural sources of chlorine and bromine to the stratosphere. The production of these gases is dominated by natural sources, but smaller, important anthropogenic sources, such as agricultural fumigation and/or biomass burning, also exist. As absorbers of infrared radiation these gases are of interest for their potential effect on the tropospheric energy balance as well as for chemical interactions. In this study we estimate the radiative forcing and Global Warming Potentials (GWPs) of CH3Cl and CH3Br. Our calculations use an infrared radiative transfer model based on the correlated k-distribution algorithm for band absorption. Radiative forcing values of 0.0047 W/m2 per part per billion by volume (ppbv) for CH3Cl in the troposphere and 0.0049 W/m2 per ppbv for CH3Br in the troposphere were obtained. On a per molecule basis the radiative forcing values are about 2% of the forcing of CFC-11 and about 270 times the forcing of CO2. GWPs for these gases are about 8 for CH3Cl and about 4 for CH3Br (100 year time integration, CO2=1). These results indicate that while CH3Cl and CH3Br have direct GWPs similar to that of CH4, the current emission rates are too low to contribute meaningfully to atmospheric greenhouse heating effects.

Grossman, Allen S.; Grant, Keith E.; Blass, William E.; Wuebbles, Donald J.

1997-06-01

227

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

228

MiR-21 plays an Important Role in Radiation Induced Carcinogenesis in BALB/c Mice by Directly Targeting the Tumor Suppressor Gene Big-h3  

PubMed Central

Dysregulation of certain microRNAs (miRNAs) in cancer can promote tumorigenesis, metastasis and invasion. However, the functions and targets of only a few mammalian miRNAs are known. In particular, the miRNAs that participates in radiation induced carcinogenesis and the miRNAs that target the tumor suppressor gene Big-h3 remain undefined. Here in this study, using a radiation induced thymic lymphoma model in BALB/c mice, we found that the tumor suppressor gene Big-h3 is down-regulated and miR-21 is up-regulated in radiation induced thymic lymphoma tissue samples. We also found inverse correlations between Big-h3 protein and miR-21 expression level among different tissue samples. Furthermore, our data indicated that miR-21 could directly target Big-h3 in a 3?UTR dependent manner. Finally, we found that miR-21 could be induced by TGF?, and miR-21 has both positive and negative effects in regulating TGF? signaling. We conclude that miR-21 participates in radiation induced carcinogenesis and it regulates TGF? signaling. PMID:21494432

Liu, Cong; Li, Bailong; Cheng, Ying; Lin, Jing; Hao, Jun; Zhang, Shuyu; Mitchel, R.E.J.; Sun, Ding; Ni, Jin; Zhao, Luqian; Gao, Fu; Cai, Jianming

2011-01-01

229

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

PubMed Central

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

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

2015-01-01

230

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

PubMed

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

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

2014-09-01

231

Electrochemical analysis of clinical blood-gases, gases and vapours.  

PubMed

This tutorial review charts the development of electrochemical sensors for the analysis of blood-gases, gases and vapours in clinical medicine over the past four decades. The development of each sensor is set in its historical and clinical context, and the first part of the review concentrates on aqueous electrolyte electrochemistry and on those sensors which have made a major impact on the clinical measurement of the partial pressures of oxygen and carbon dioxide in the blood. The electrochemical interference effects of anaesthetic agents on these measurements are also described. Those electrochemical sensors which have failed, in the past, to make a clear impact in this area are not considered, but the few attempts to devise aqueous electrolyte electrochemical sensors for anaesthetic agent measurement are reviewed. The second part of the review describes the chequered history of the development of non-aqueous solvent electrochemical sensors to measure the partial pressures of oxygen and carbon dioxide, in both the presence and absence of each other, in the gas phase. The last part of the review examines various attempts, using non-aqueous solvent electrochemistry, to measure the concentration of inhalational anaesthetic vapours in the gas phase. These sensors have yet to make an impact on clinical practice. Throughout this tutorial review, theoretical models of membrane-covered electrochemical sensors are described where appropriate. This review represents a personal view of the development of electrochemical sensors for clinical measurement, and it is therefore necessarily selective in its approach and emphasis. PMID:9764506

Hahn, C E

1998-06-01

232

Noble Gases in the Earth's Core?  

NASA Astrophysics Data System (ADS)

Chemical inertness, surface volatility and low abundance have made the noble gases a unique trace elemental and isotopic system for constraining the formation and evolution of the solid Earth and its atmosphere. This geochemical role parallels extensive physical-property measurements on the condensed rare gases alone at the pressures equivalent to those of the Earth's deep mantle and core from diamond-anvil cell (DAC) experiments. Traditional geochemical approaches to the processes of planetary evolution have involved crystal-melt partitioning at low pressures relevant more to near-surface degassing. The degree of compatibility has fluctuated among different studies and largely rests with the conclusion that, for common upper mantle phases, the noble gases are highly incompatible. But the long-known high 3He/4He ratios for some ocean-island basalts and more recent observations for some of the rare gases (Ne, Ar and possibly Xe) that there is a solar component emanating from the Earth, continue to raise questions on the source reservoir as well as on accretionary and incorporation processes. Changes in models of mantle convection style have made it harder to rely on the deep mantle as a reservoir, and the core has remained a particularly unfavourable location either because of difficulty in constructing a retention mechanism during planetary accretion or simply because of lack of data: Partitioning studies at pressure are rare and complicated by the difficulty in reproducing not only absolute concentrations, but confinement of gas in high-pressure apparatus and post-run analysis. We have investigated noble gas solubility in silicate liquids at high pressures in a DAC (relevant to a magma-ocean model of the early Earth) that suggests that the detailed composition and structure of silicate liquids may act as an important control on the level of incompatibility. The long-held idea of partial melting as a single-stage, efficient process for extracting noble gases from the Earth's mantle at all depths, may well be oversimplified. For molten metal compositions interacting with silicate melt, Matsuda et al. (1993) defined the near-zero limits of noble gas solubility expected in metal with increasing pressure. We re-visit the phenomenological aspect of (saturated) noble gas solubility in metals with new experiments in noble gas pressure-transmitting media in the laser-heated DAC. First results with argon analysed with SEM methods suggest up to an order of magnitude higher partition coefficient (D(Ar)Fe/sil ˜ 0.1) for liquids in the DAC at 5 GPa. We have also recovered samples for analysis with more sensitive UV laser-ablation mass spectroscopic techniques that provide additional, depth-resolved constraints on noble gas solubility at moderate pressures.

Jephcoat, A. P.; Bouhifd, M. A.; Heber, V.; Kelley, S. P.

2004-12-01

233

Atmospheric Chemistry and Greenhouse Gases  

Microsoft Academic Search

Contents4.1 Earth Observing System (EOS) program objectives 1674.2 Introduction 1684.2.1 Science questions 1684.2.1.1 How does changing land\\/land use affect fluxes of greenhouse gases such asCO 2 , methane, and nitrous oxide? How does it affect O 3 precursors fromsoil (e.g., NO), plant (e.g., biogenic nonmethane hydrocarbons), emissions,and biomass-burning plumes? 1684.2.1.2 How does interannual variability in climate affect interannual variability inbiogeochemistry?

D. Schimel; D. Glover; J. Melack; R. Beer; R. Myneni

234

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

235

Effect of vincristine or bleomycin on radiation-induced cell killing of mice spermatogonial stem cells: The importance of sequence and time interval  

SciTech Connect

The effect of single doses of vincristine (VCR) or bleomycin (BLM) on mice spermatogonia was investigated, and the influence of either of these drugs on the radiation response of murine spermatogonial stem cells was examined. When assessed by flow cytometry, VCR (1.0 mg/kg) or BLM (100 mg/kg) reduced the survival in the differentiated spermatogonia to 4% and 37% of controls, respectively (p less than 0.05). VCR reduced the stem cells to 79% of controls (p less than 0.05), whereas BLM had no apparent effect on the stem cells (p greater than 0.05). Drugs were administered intraperitoneally up to 28 days before or after local irradiation with 9 Gy. VCR produced significant enhancement of radiation-induced damage to spermatogonial stem cells, which was most prominent when administered 6 or 12 hr after irradiation. BLM administered before irradiation or 1 hr after radiotherapy produced significant enhancement.

Hansen, P.V.; Sorensen, D. (Danish Cancer Society, Aarhus (Denmark))

1991-02-01

236

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

237

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

SciTech Connect

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

Chang, Daniel T. [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Feigenberg, Steven J. [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Indelicato, Daniel J. [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Morris, Christopher G. [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Lightsey, Judith [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States); Grobmyer, Stephen R. [Department of Surgery, University of Florida College of Medicine, Gainesville, FL (United States); Copeland, Edward M. [Department of Surgery, University of Florida College of Medicine, Gainesville, FL (United States); Mendenhall, Nancy P. [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, FL (United States)]. E-mail: mendenan@shands.ufl.edu

2007-03-15

238

Predicting Flows of Rarefied Gases  

NASA Technical Reports Server (NTRS)

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

LeBeau, Gerald J.; Wilmoth, Richard G.

2005-01-01

239

THERMODYNAMIC PARAMETERS FOR DISSOLVED GASES*  

PubMed Central

In 1958 and subsequently we correlated properties of solutions of gases in liquids by using the “force constants,” ?/k, and collision diameters, ?, which serve as parameters in equations for molecular pair potential energy such as that of Lennard-Jones or its variants. Unfortunately, however, the figures for these parameters that have been published are so scattered for the same gas as to make it difficult to select “best” values; in 1967, therefore, I substituted for these indirectly determined molecular parameters the directly and accurately known molal energy of vaporization, ?Ebv, and the molal volume, vb, of the liquefied gas, both at its boiling point. A plot of values of ?E2v against the most trustworthy values of ?/k reveals direct proportionality. The same is true for Vb1/3 versus ?. Recent examples will be shown of excellent linear correlations with these parameters of thermodynamic properties of different gases in the same solvent. It is no less “scientific” and far more practical to regard molecules of a solute as immersed in the potential energy field of its solvent than it is to split this field into imperfectly known pair potentials of questionable additivity and to try to integrate them over an undetermined distribution function. PMID:16591809

Hildebrand, Joel H.

1969-01-01

240

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

241

Physics of intense, high energy radiation effects.  

SciTech Connect

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

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

2011-02-01

242

Investigation of ultrafast laser-driven radiative blast waves.  

PubMed

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

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

2001-08-20

243

Effect of photolysis on seeding gases in a TEA CO2 laser  

NASA Astrophysics Data System (ADS)

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

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

1985-04-01

244

Angular correlation studies in noble gases  

NASA Technical Reports Server (NTRS)

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

Coleman, P. G.

1990-01-01

245

Solar radiation resource assessment  

SciTech Connect

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

Not Available

1990-11-01

246

Importance of the mini-mental status examination in the treatment of patients with brain metastases: a report from the radiation therapy oncology group protocol 91-04  

Microsoft Academic Search

Purpose: Little information is available on the importance of pretreatment Mini-Mental Status Exam (MMSE) on long-term survival and neurologic function following treatment for unresectable brain metastases. This study examines the importance of the MMSE in predicting outcome in a group of patients treated with an accelerated fractionation regimen of 30 Gy in 10 daily fractions in 2 weeks.Materials and Methods:

Kevin J Murray; Charles Scott; Babu Zachariah; Jeff M Michalski; William Demas; Nayana L Vora; Anthony Whitton; Benjamin Movsas

2000-01-01

247

Radiation-induced ignition  

SciTech Connect

The effects of gas-phase radiation absorption on radiative ignition of various combustible materials under gravity conditions are studied. The physical models in this study range from a simple gas layer to a complex porous structure. Methyl methacrylate (MMA: C{sub 5}H{sub 8}O{sub 2}) vapor has been selected as a representative of participating gases in gas-phase radiation interactions. Its infrared radiation properties were measured using low-resolution spectral apparatus and then correlated in simple usable forms. As expected from its complex molecular structure, the infrared absorption capabilities of MMA vapor is much stronger than those of simpler hydrocarbon gases as well as water vapor and carbon dioxide. Radiation induced ignition was analyzed on the basis of simple theoretical models. Using Semenov's theory, results indicate a decrease in the critical surrounding temperature for a low Biot number system. For a high Biot number system, ignitability is defined through the use of Frank-Kamenetskii's critical parameter delta. One-dimensional transient models were developed for the analyses of radiation induced ignition of solid and porous solid fuels. The models include gas-phase radiation absorption, in-depth radiation interaction by the solid phase, Arrhenius-type chemical reaction, and natural convection. Predicted transmittance during ignition processes confirms the attenuation of incident radiation by pyrolyzed gases which has been already observed experimentally. An ignition process with gas-phase radiation absorption results in a quite different and widened ignition domain compared to that without gas-phase radiation absorption. Moreover, ignition is totally dependent on gas-phase radiation absorption under unfavorable conditions for a thermal runaway.

Park, S.

1989-01-01

248

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.

249

D-dimensional Bose gases and the Lambert W function  

NASA Astrophysics Data System (ADS)

The applications of the Lambert W function (also known as the W function) to D-dimensional Bose gases are presented. We introduce two sets of families of logarithmic transcendental equations that occur frequently in thermodynamics and statistical mechanics and present their solution in terms of the W function. The low temperature T behavior of free ideal Bose gases is considered in three and four dimensions. It is shown that near condensation in four dimensions, the chemical potential ? and pressure P can be expressed in terms of T through the W function. The low T behavior of one- and two-dimensional ideal Bose gases in a harmonic trap is studied. In 1D, the W function is used to express the condensate temperature, T_C, in terms of the number of particles N; in 2D, it is used to express ? in terms of T. In the low T limit of the 1D hard-core and the 3D Bose gas, T can be expressed in terms of P and ? through the W function. Our analysis allows for the possibility to consider ?, T, and P as complex variables. The importance of the underlying logarithmic structure in ideal quantum gases is seen in the polylogarithmic and W function expressions relating thermodynamic variables such as ?, T, and P.

Tanguay, J.; Gil, M.; Jeffrey, D. J.; Valluri, S. R.

2010-12-01

250

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

251

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

252

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

253

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.

254

Multiple direct and sequential Auger effect in the rare gases  

SciTech Connect

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

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

2006-01-09

255

Thermodynamic and hydrodynamic behaviour of interacting Fermi gases  

E-print Network

with the development of advanced cooling techniques like laser cooling and evaporative cooling could such low temperatures be achieved. But why is the study of ultracold gases so important in the first place? Partial Bose-Einstein condensation can be observed in liquid... orders of magnitude lower than of the air surrounding us, not to mention denser systems like liquids or solids. To observe quantum phenomena at such low densities temperatures below 10?5 K are required – a major technical challenge. Only...

Goulko, Olga

2012-01-10

256

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

257

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

258

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

259

Facilitating Conceptual Change in Gases Concepts  

ERIC Educational Resources Information Center

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…

Cetin, Pinar Seda; Kaya, Ebru; Geban, Omer

2009-01-01

260

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

261

Irradiated gases transferred without contamination or dilution  

NASA Technical Reports Server (NTRS)

Vacuum chamber apparatus opens sealed canisters of irradiated gases and transfers the contents without contaminating the surrounding area, and without diluting or polluting the contained gases. The apparatus consists of the chamber, a valved piping manifold, and a special drill and sealed drilling access.

Bonn, J. L.; Kern, W.

1967-01-01

262

Predict thermal conductivities of pure gases  

SciTech Connect

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

Weber, J.H.

1981-01-01

263

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

264

Research of medical gases in Poland  

PubMed Central

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

2013-01-01

265

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

266

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

267

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

PubMed

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

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

2015-01-01

268

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

PubMed Central

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

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

2015-01-01

269

Superradiant Decay of Cyclotron Resonance of Two-Dimensional Electron Gases Takashi Arikawa,1,*  

E-print Network

Superradiant Decay of Cyclotron Resonance of Two-Dimensional Electron Gases Qi Zhang,1 Takashi on the observation of collective radiative decay, or superradiance, of cyclotron resonance (CR) in high-mobility two through cyclotron resonance (CR) absorption [7]. How rapidly the coherence of this many-body superposition

Natelson, Douglas

270

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

Microsoft Academic Search

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

James E. Hansen; Andrew A. Lacis

1990-01-01

271

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

272

Electron interactions with plasma processing gases – Progress of magnetized electron-impact total cross section measurement system(ELECS-1)  

Microsoft Academic Search

Electron-impact cross sections for molecular targets, including their radicals, are important in developing plasma reactors and testing various plasma processing gases. However, we suffer from lack of theoretical and experimental electron-impact cross section data for plasma processing gas, such as plasma etching and deposition processes. Thus, in this work, the total cross sections for electron scattering from plasma processing gases

Dae Chul Kim; Mi-Young Song; Yonghyun Kim; Young-Woo Kim; Young Rock Choi; Jung-Sik Yoon; Hyck Cho

273

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

274

30 CFR 18.25 - Combustible gases from insulating material.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Combustible gases from insulating material...OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND...Requirements § 18.25 Combustible gases from insulating material...give off flammable or explosive gases when decomposed...

2013-07-01

275

40 CFR 600.108-08 - Analytical gases.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Analytical gases. 600.108-08 Section 600... FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF MOTOR VEHICLES Fuel Economy and Carbon-Related... § 600.108-08 Analytical gases. The analytical gases...

2012-07-01

276

30 CFR 18.25 - Combustible gases from insulating material.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Combustible gases from insulating material...OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND...Requirements § 18.25 Combustible gases from insulating material...give off flammable or explosive gases when decomposed...

2012-07-01

277

30 CFR 18.25 - Combustible gases from insulating material.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Combustible gases from insulating material...OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND...Requirements § 18.25 Combustible gases from insulating material...give off flammable or explosive gases when decomposed...

2010-07-01

278

40 CFR 600.108-08 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Analytical gases. 600.108-08 Section 600... FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF MOTOR VEHICLES Fuel Economy and Carbon-Related... § 600.108-08 Analytical gases. The analytical gases...

2013-07-01

279

40 CFR 600.108-78 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Analytical gases. 600.108-78 Section 600...CARBON-RELATED EXHAUST EMISSIONS OF MOTOR VEHICLES Fuel Economy Regulations... § 600.108-78 Analytical gases. The analytical gases for all fuel economy testing...

2010-07-01

280

40 CFR 600.108-78 - Analytical gases.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Analytical gases. 600.108-78 Section 600...CARBON-RELATED EXHAUST EMISSIONS OF MOTOR VEHICLES Fuel Economy and... § 600.108-78 Analytical gases. The analytical gases for all fuel economy testing...

2011-07-01

281

30 CFR 18.25 - Combustible gases from insulating material.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Combustible gases from insulating material...OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND...Requirements § 18.25 Combustible gases from insulating material...give off flammable or explosive gases when decomposed...

2014-07-01

282

30 CFR 18.25 - Combustible gases from insulating material.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Combustible gases from insulating material...OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND...Requirements § 18.25 Combustible gases from insulating material...give off flammable or explosive gases when decomposed...

2011-07-01

283

49 CFR 173.307 - Exceptions for compressed gases.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Exceptions for compressed gases. 173.307 Section 173.307 Transportation...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.307 Exceptions for compressed gases. (a) The following materials...

2013-10-01

284

49 CFR 173.307 - Exceptions for compressed gases.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 false Exceptions for compressed gases. 173.307 Section 173.307 Transportation...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.307 Exceptions for compressed gases. (a) The following materials...

2014-10-01

285

49 CFR 173.307 - Exceptions for compressed gases.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Exceptions for compressed gases. 173.307 Section 173.307 Transportation...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.307 Exceptions for compressed gases. (a) The following materials...

2011-10-01

286

49 CFR 173.307 - Exceptions for compressed gases.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Exceptions for compressed gases. 173.307 Section 173.307 Transportation...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.307 Exceptions for compressed gases. (a) The following materials...

2010-10-01

287

49 CFR 173.307 - Exceptions for compressed gases.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Exceptions for compressed gases. 173.307 Section 173.307 Transportation...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.307 Exceptions for compressed gases. (a) The following materials...

2012-10-01

288

Driven fragmentation of granular gases  

NASA Astrophysics Data System (ADS)

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

Cruz Hidalgo, Raúl; Pagonabarraga, Ignacio

2008-06-01

289

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

290

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

NASA Astrophysics Data System (ADS)

Increasing levels of certain greenhouse gases (GHGs), most importantly CO2 in the earths atmosphere, lead to climate change and global warming as a result of these gases interacting with thermal infrared (TIR) radiation from earth to space. Here, the option of modifying this radiation is analyzed which would result in modified TIR radiation that would interact less with atmospheric CO2. This alleviates the enhanced greenhouse effect, and at the same time would allow for energy recovery as heat and/or power. Power production is, of course, limited by thermodynamics Second Law. It is shown that various options exist for TIR radiation modification which may be used to generate temperature gradients or temperature differences between volumes of (gases containing) CO2 of sufficient optical thickness. This may be further exploited for power generation: a first, simple case shows power generation of ˜1 W per m2 surface at a Carnot efficiency of ˜7%, using the sky and ground level surroundings as heat reservoirs.

Zevenhoven, Ron

2008-08-01

291

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

292

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

293

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

294

Detailed Investigations of Interactions between Ionizing Radiation and Neutral Gases  

SciTech Connect

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

Landers, Allen L

2014-03-31

295

Fluctuations in Quantum Degenerate Fermi Gases  

E-print Network

suppression of spin fluctuations below shot noise, and can be universally applied to trapped quantum gases completely shielded from all annoyances that normally constrain life. Being one of the shy animals I am very

296

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

297

40 CFR 1065.750 - Analytical gases.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

298

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

299

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

300

Nanoindentation of GaSe thin films  

PubMed Central

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

2012-01-01

301

Nanoindentation of GaSe thin films  

NASA Astrophysics Data System (ADS)

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

Jian, Sheng-Rui; Ku, Shin-An; Luo, Chih-Wei; Juang, Jenh-Yih

2012-07-01

302

The In-Vitro Transport of (238)PLUTONIUM Oxide and (239)PLUTONIUM Oxide Through a Membrane Filter and its Importance for Internal Radiation Dosimetry.  

NASA Astrophysics Data System (ADS)

These experiments were designed to determine if ('238)PuO(,2), due to its higher specific activity and attendant aggregate recoil, undergoes higher transfer through a membrane filter into an interstitial human alveolar lung fluid simulant than ('239)PuO(,2). The rate at which such transfer occurs was determined in an in-vitro chamber designed to simulate residence characteristics of particles of insoluble plutonium oxides in human alveolar interstitium. The ratio of the rate of ('238)Pu/('239)Pu transfer was 138 (+OR -) 76%. Calculations were performed to assess the importance of this finding in terms of the internal dosimetry of insoluble ('238)Pu using methods and models recommended by the International Commission on Radiological Protection. Three cases were evaluated, namely integral 50-year dose commitment, urinary excretion after single acute intake and urinary excretion rate during chronic constant intake. It was found that integral 50-year dose commitments were not influenced by the rate of plutonium transfer from the pulmonary compartment to blood. The evaluation of calculated urinary excretion data after a single acute inhalation intake showed that in the early period, up to about 30 days post exposure, urinary excretion of ('238)PuO(,2) may be 2 to 10 times higher than the urinary excretion rate for ('238)PuO(,2) predicted by the ICRP reference model. From about 50 days to approximately 1000 days the calculated urinary excretion rate for ('238)PuO(,2) may be lower than that predicted by the reference model by a factor of 2 to 10. In the case of chronic constant intake the calculated urinary excretion rate for ('238)PuO(,2) may be up to a factor of 2 higher than that predicted by the reference ICRP Model.

Ryan, Michael Terrance

303

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

304

Extended thermodynamics of molecular ideal gases  

NASA Astrophysics Data System (ADS)

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

Kremer, G. M.

1989-02-01

305

Biological production of products from waste gases  

DOEpatents

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

Gaddy, James L. (Fayetteville, AR)

2002-01-22

306

Classification and generation of terrestrial rare gases  

NASA Technical Reports Server (NTRS)

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

Saito, K.

1978-01-01

307

Experimental Research of Pyrolysis Gases Cracking on Surface of Charcoal  

NASA Astrophysics Data System (ADS)

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

Kosov, Valentin; Kosov, Vladimir; Zaichenko, Victor

308

Emissions of greenhouse gases in the United States 1996  

SciTech Connect

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

NONE

1997-10-01

309

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

310

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...

311

Mesospheric Removal of Very Long-Lived Greenhouse Gases SF6 and CFC-115 by Metal Reactions, Lyman-? Photolysis, and Electron Attachment.  

PubMed

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

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

2015-03-12

312

Experimental investigation of the chemistry of excited states of rare gases. Progress report, October 15, 1976July 1, 1977  

Microsoft Academic Search

Research progress is reported on the fluorescence and quenching of rare gases. The data being gathered will be of fundamental importance to rare gas chemistry and physics, as well as being of practical value for laser systems. (TFD)

Setser

1977-01-01

313

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

314

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

315

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

316

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

ERIC Educational Resources Information Center

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

Niaz, Mansoor

2000-01-01

317

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

E-print Network

UNIVERSITY OF TECHNOLOGY ENE-47.153 The enhancedThe enhanced greenhouse effectgreenhouse effect #12;HELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153 The enhanced greenhouse effect: sourcesThe enhanced greenhouse effectHELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153 Greenhouse gases andGreenhouse gases and ozone

Zevenhoven, Ron

318

Condensate fluctuations of interacting Bose gases within a microcanonical ensemble  

SciTech Connect

Based on counting statistics and Bogoliubov theory, we present a recurrence relation for the microcanonical partition function for a weakly interacting Bose gas with a finite number of particles in a cubic box. According to this microcanonical partition function, we calculate numerically the distribution function, condensate fraction, and condensate fluctuations for a finite and isolated Bose-Einstein condensate. For ideal and weakly interacting Bose gases, we compare the condensate fluctuations with those in the canonical ensemble. The present approach yields an accurate account of the condensate fluctuations for temperatures close to the critical region. We emphasize that the interactions between excited atoms turn out to be important for moderate temperatures.

Wang Jianhui; He Jizhou; Ma Yongli [Department of Physics, Nanchang University, Nanchang 330031 (China); Department of Physics, Fudan University, Shanghai 200433 (China)

2011-05-15

319

On the theory of impulse breakdown in gases  

NASA Astrophysics Data System (ADS)

In recent years it has become important to have a fast, efficient, and reliable switch for pulse power systems. Two types of switches have been proposed to date: the solid state switch and the plasma switch. This report provided an analysis of the plasma switch. A microscopic description of the fast switching phenomena in gases was developed. This theory accounts for diffusion of both electrons and ions. From it, Dickey's phenomenological equation was derived. The parameters appearing in Dickey's phenomenological equation were determined for various experimental conditions. Finally, the fast switching analysis of voltage based on the phenomenological equation was done.

Wartak, M. S.; Podgorski, A. S.

1990-05-01

320

Effects of meteoric debris on stratospheric aerosols and gases  

NASA Technical Reports Server (NTRS)

Characterizations of meteoric dust height and size distributions are obtained using Hunten's calculations of meteor ablation and recondensation rates. The contribution of meteor residues to aerosol composition, the role of meteoric dust as condensation nuclei, and the effects of meteor debris on aerosol size distributions are quantified, and particle surface areas are estimated. The potential importance of heterogeneous chemistry for stratospheric trace gases is discussed. The interaction between H2SO4 vapor and meteor metal vapors is investigated. It is concluded that meteoric particles may dominate the natural stratospheric aerosols at small (less than .01 micron radius) and large (greater than 1 micron radius) sizes under normal conditions.

Turco, R. P.; Toon, O. B.; Whitten, R. C.; Hamill, P.

1981-01-01

321

In-situ infrared detection of stack gases  

NASA Astrophysics Data System (ADS)

Infrared measurement using gas-filter correlation (GFC) detection offers an accurate, sensitive, and highly selective technique for the quantitative detection of a number of common industrial gases. A radiative transfer model based on the HITRAN database has been developed to permit the response function of such an instrument to be calculated. The model has been applied to a number of gases, calculating the instrument response to both the target gas and selected interferent species over a broad range of stack temperatures. An optical probe GFC detector has been designed for in-stack measurements of CO and HCl from incinerators and thermal power stations. The probe can be purged with clean air for a true baseline check and a calibration chamber is provided which allows the instrument to be calibrated using bottled gas mixtures. The instrument has completed a successful plant trial during which it measured CO emissions from a coal-fired power station, showing a detection sensitivity of 5 ppm. Detection of HCl has also been demonstrated in the laboratory.

Stuart, Derek D.

1993-03-01

322

The importance of the Montreal Protocol in protecting climate  

PubMed Central

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

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

2007-01-01

323

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

324

Maximum entropy principle for rarefied polyatomic gases  

NASA Astrophysics Data System (ADS)

The aim of this paper is to show that the procedure of maximum entropy principle for the closure of the moments equations for rarefied monatomic gases can be extended also to polyatomic gases. The main difference with respect to the usual procedure is the existence of two hierarchies of macroscopic equations for moments of suitable distribution function, in which the internal energy of a molecule is taken into account. The field equations for 14 moments of the distribution function, which include dynamic pressure, are derived. The entropy and the entropy flux are shown to be a generalization of the ones for classical Grad’s distribution. The results are in perfect agreement with the recent macroscopic approach of extended thermodynamics for real gases.

Pavi?, Milana; Ruggeri, Tommaso; Simi?, Srboljub

2013-03-01

325

Where do California's greenhouse gases come from?  

ScienceCinema

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

Fischer, Marc

2013-05-29

326

Laser plume temperature measurements in various gases  

SciTech Connect

Nd-YAG laser plume temperatures of 3000--5400K were measured on 304 stainless steel and 1100 Al in various gases using emission spectroscopy. Temperatures were higher in the reactive gases air, 02, and SF6, compared to inert gases. Ionic spectra were not observed, indicating that the plume primarily consists of hot vapors and does not contain a plasma, in contrast to CO/sub 2/ laser processing in which plasmas have been observed. The plume temperature remained constant with changes in laser power and with time during the duration of the laser pulse. Light emissions from the plume and from the cooling weld pool after the laser pulse was off were measured and correlated with melt depth. 7 refs.

Lewis, G.K.; Cremers, D.A.; Dixon, R.D.

1988-01-01

327

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

SciTech Connect

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

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

1993-11-01

328

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

329

Radiation Symbols  

MedlinePLUS

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

330

Stationary light in cold atomic gases  

E-print Network

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

Gor Nikoghosyan; Michael Fleischhauer

2009-09-16

331

Seeing spin dynamics in atomic gases  

E-print Network

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

Dan M. Stamper-Kurn

2014-12-31

332

Managing biogeochemical cycles to reduce greenhouse gases  

SciTech Connect

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

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

2012-01-01

333

Measuring Viscosities of Gases at Atmospheric Pressure  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

334

Electronic properties and influence of doping on GaSe crystal nonlinear optical parameters for the applications in terahertz range  

NASA Astrophysics Data System (ADS)

In the present paper the results of the study of semiconductor and optical properties of GaSe crystals important for their applications in nonlinear optics of terahertz and mid-IR ranges are reported as well as influence of doping with isovalent chemical elements on them. The performed first-principles calculations of charge neutrality level (CNL) in GaSe have shown its position at 0.8 eV above the top of the valence band. The location of CNL in the lower part of the band gap can explain GaSe intrinsic p-type of conductivity. In this case it is necessary to radically improve the growth technology to obtain GaSe crystals with low free carrier concentrations. Extraordinarily large birefringence of GaSe B~0.8 in terahertz range has been measured directly. In order to study the potential efficiency of application of doped GaSe crystals for terahertz generation and detection their study using terahertz time domain spectroscopy (THz-TDS) setup has been performed. According to the obtained results doped GaSe crystals are slightly less efficient for terahertz detection and generation in the frequency range 0.2-3.2 THz via optical rectification of laser pulses with ?=790 nm and ?=80 fs. On the other hand doping of GaSe with In, Al, S, Te leads to 2-3 times increase of the microhardness and the doped crystals become suitable for the mechanical treatment.

Nazarov, M. M.; Kosobutsky, A. V.; Sarkisov, S. Yu.; Brudnyi, V. N.; Tolbanov, O. P.; Shkurinov, A. P.

2010-09-01

335

Indirect radiative forcing efficiencies of spatially resolved aerosol and precursor gas emissions  

NASA Astrophysics Data System (ADS)

Linking indirect radiative forcing to aerosol and precursor gas emissions clarifies an important pathway by which anthropogenic emissions affect climate through tropospheric chemistry. Cloud condensation nuclei (CCN) concentrations and meteorological conditions at droplet activation height modulate the cloud droplet number concentration (CDNC); with greater CDNC, clouds reflect sunlight more effectively. CCN concentrations are perturbed not only by direct aerosol emissions but also by tropospheric chemical interactions of precursor gases. The short-lived nature of aerosol and their radiative effects underscores the importance of spatial specificity when attributing forcing to emissions. Here, we evaluate the relative influence of emissions on radiative forcing in a computationally efficient manner; the method is extensible to future climatic conditions where the efficiencies may be modified due to changes in tropospheric chemical composition or meteorological conditions. We present indirect radiative forcing efficiencies of spatially refined aerosol and precursor gas emissions. The GEOS-Chem adjoint (Henze et al., 2007) coupled with the adjoint of a droplet activation parameterization (Karydis et al., 2012) calculates the relative influence of aerosol and precursor gas emissions on CDNC. Uncertainty due to the prescribed droplet activation height is explored. Modulation of radiative forcing by CDNC is determined by the Linearized Discrete Ordinate Radiative Transfer (LIDORT) model (Spurr, 2008). These novel quantities are compared with the aerosol direct radiative forcing efficiencies of Henze et al. (2012). Quantifying radiative efficiencies of aerosol and precursor gas emissions provides environmental decision makers an estimate of climate forcing expected due to moderate emissions perturbations possible with policy changes.

Capps, S. L.; Henze, D. K.; Karydis, V.; Russell, A. G.; Nenes, A.

2013-12-01

336

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

E-print Network

. By means of a stack of sufficient height these can be dispersed into the atmosphere without much effect summer days is a good example of what happens when large amounts of flue gases are released at ground concentrations in the atmosphere are rising at ~1% per year from ~355 ppmv (parts per million by volume) in 1990

Zevenhoven, Ron

337

Influence of nearly resonant light on the scattering length in low-temperature atomic gases  

Microsoft Academic Search

We develop the idea of manipulating the scattering length $a$ in\\u000alow-temperature atomic gases by using nearly resonant light. As found, if the\\u000aincident light is close to resonance with one of the bound $p$ levels of\\u000aelectronically excited molecule, then virtual radiative transitions of a pair\\u000aof interacting atoms to this level can significantly change the value and even

P. O. Fedichev; Y. M. Kagan; G. V. Shlyapnikov; J. T. M. Walraven

1996-01-01

338

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

Microsoft Academic Search

A numerical 2-D zonally averaged interactive dynamical radiative-photochemical model of the atmosphere including aerosol physics is used to examine the impact of the greenhouse gases CO2, CH4, and N2O on the future long-term changes of the Earth's ozone layer, in particular on its expected recovery after reduction of anthropogenic discharges of chlorine and bromine compounds into the atmosphere. The model

Alexander Zadorozhny; Igor Dyominov

2010-01-01

339

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

340

Fullerenes and the Nature of Planetary Gases  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

341

Behavior of Gases: Disaster at Lake Nyos  

NSDL National Science Digital Library

Students, through discussion and structured inquiry, will learn about the behavior of gases under various conditions. Students will be able to apply these concepts to everyday objects such as soda bottles, fire extinguishers, hot air balloons, propane tanks, and aerosol products.

Bryan Wilk

2012-07-13

342

Sulfur dioxide in geothermal waters and gases  

Microsoft Academic Search

Methods were developed for stabilizing SO 2 in water and gas samples. The pararosaniline colorimetric method, and a gas Chromatographic method using a flame photometric detector specific for sulfur gases were used to assay SO 2 . Assays were also performed for sulfide, elemental sulfur and sulfate. A large number of acidic, neutral, and alkaline springs in Yellowstone National Park

Stephen Zinder; Thomas D. Brock

1977-01-01

343

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

344

Connecting Chemical Dynamics in Gases and Liquids  

E-print Network

Connecting Chemical Dynamics in Gases and Liquids Christopher G. Elles and F. Fleming Crim, Annu the energies slightly : intimate part of the chemistry #12;Introduction Goal in this review ­ Examine recent : extensively studied : infancy #12;Theory #12;Transition state Unifying concept in chemistry Influence

Ihee, Hyotcherl

345

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

346

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

347

Pseudogap phenomena in ultracold atomic Fermi gases  

NASA Astrophysics Data System (ADS)

The pairing and superfluid phenomena in a two-component ultracold atomic Fermi gas is an analogue of Cooper pairing and superconductivity in an electron system, in particular, the high T c superconductors. Owing to the various tunable parameters that have been made accessible experimentally in recent years, atomic Fermi gases can be explored as a prototype or quantum simulator of superconductors. It is hoped that, utilizing such an analogy, the study of atomic Fermi gases may shed light to the mysteries of high T c superconductivity. One obstacle to the ultimate understanding of high T c superconductivity, from day one of its discovery, is the anomalous yet widespread pseudogap phenomena, for which a consensus is yet to be reached within the physics community, after over 27 years of intensive research efforts. In this article, we shall review the progress in the study of pseudogap phenomena in atomic Fermi gases in terms of both theoretical understanding and experimental observations. We show that there is strong, unambiguous evidence for the existence of a pseudogap in strongly interacting Fermi gases. In this context, we shall present a pairing fluctuation theory of the pseudogap physics and show that it is indeed a strong candidate theory for high T c superconductivity.

Chen, Qijin; Wang, Jibiao

2014-10-01

348

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

349

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

350

Evaluation of radiation scheme performance within chemistry climate models  

NASA Astrophysics Data System (ADS)

This paper evaluates global mean radiatively important properties of chemistry climate models (CCMs). We evaluate stratospheric temperatures and their 1980-2000 trends, January clear sky irradiances, heating rates, and greenhouse gas radiative forcings from an offline comparison of CCM radiation codes with line-by-line models, and CCMs' representation of the solar cycle. CCM global mean temperatures and their change can give an indication of errors in radiative transfer codes and/or atmospheric composition. Biases in the global temperature climatology are generally small, although five out of 18 CCMs show biases in their climatology that likely indicate problems with their radiative transfer codes. Temperature trends also generally agree well with observations, although one model shows significant discrepancies that appear to be due to radiation errors. Heating rates and estimated temperature changes from CO2, ozone, and water vapor changes are generally well modeled. Other gases (N2O, CH4, and CFCs) have only played a minor role in stratospheric temperature change, but their heating rates have large fractional errors in many models. Models that do not account for variations in the spectrum of solar irradiance cannot properly simulate solar-induced variations in stratospheric temperature. The combined long-lived greenhouse gas global annual mean instantaneous net radiative forcing at the tropopause is within 30% of line-by-line models for all CCM radiation codes tested. Problems remain in simulating radiative forcing for stratospheric water vapor and ozone changes with errors between 3% and 200% compared to line by line models. The paper makes recommendations for CCM radiation code developers and future intercomparisons.

Forster, Piers M.; Fomichev, Victor I.; Rozanov, Eugene; Cagnazzo, Chiara; Jonsson, Andreas I.; Langematz, Ulrike; Fomin, Boris; Iacono, Michael J.; Mayer, Bernhard; Mlawer, Eli; Myhre, Gunnar; Portmann, Robert W.; Akiyoshi, Hideharu; Falaleeva, Victoria; Gillett, Nathan; Karpechko, Alexey; Li, Jiangnan; Lemennais, Perrine; Morgenstern, Olaf; OberläNder, Sophie; Sigmond, Michael; Shibata, Kiyotaka

2011-05-01

351

Tested Demonstrations: Diffusion of Gases--Kinetic Molecular Theory of Gases.  

ERIC Educational Resources Information Center

Provided are procedures and list of materials needed to demonstrate that the pressure inside a container with a porous surface can be changed due to the rate of diffusion of low molecular weight gases. Typical results obtained are included. (JN)

Gilbert, George L., Ed.

1984-01-01

352

Modelo y diseño de tren de lavado de gases provenientes de la incineración de residuos  

Microsoft Academic Search

Owing to its various deleterious effects, abatement of pollutants gases from point sources assumes significant importance over the years. In order to decrease their emissions, the design and construction of an acid gas removal from a solid waste incinerator was developed. The incinerator is located in the San Juan Industrial Park, Argentina. This system is formed by a quench and

Rodríguez Rosa; E. Echegaray Marcelo; Castro María; Palacios Carlos; Hektor Klaus; Udaquiola Stella

2008-01-01

353

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

E-print Network

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

354

Mechanisms controlling the global oceanic distribution of the inert gases argon, nitrogen and neon  

Microsoft Academic Search

Dissolved inert gas measurements in the ocean yield important information about processes that occur during water mass formation. We present argon, nitrogen, and neon data from the subtropical and subpolar North Pacific and the subtropical North Atlantic. All three gases were supersaturated at the surface. In the deep ocean, Ar and N2 were undersaturated while Ne re- mained supersaturated. All

Roberta C. Hamme; Steven R. Emerson

2002-01-01

355

Mass-transport models to predict toxicity of inhaled gases in the upper respiratory tract  

Microsoft Academic Search

Mass-transport (the movement of a chemical species) plays an important role in determining toxic responses of the upper respiratory tract (URT) to inhaled chemicals. Mathematical dosimetry models incorporate physical characteristics of mass transport and are used to predict quantitative uptake (absorption rate) and distribution of inhaled gases and vapors in the respiratory tract. Because knowledge of dose is an essential

E. A. C. Hubal; P. S. Fedkiw; J. S. Kimbell

1996-01-01

356

40 CFR 258.23 - Explosive gases control.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Explosive gases control. 258.23 Section...CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.23 Explosive gases control. (a) Owners...The concentration of methane gas generated by the...

2010-07-01

357

41 CFR 50-204.70 - Compressed gases.  

Code of Federal Regulations, 2012 CFR

...50-204.70 Compressed gases. The in-plant handling...utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or motor vehicle cargo tanks shall be in accordance with Compressed Gas Association Pamphlet...

2012-07-01

358

41 CFR 50-204.70 - Compressed gases.  

Code of Federal Regulations, 2011 CFR

...50-204.70 Compressed gases. The in-plant handling...utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or motor vehicle cargo tanks shall be in accordance with Compressed Gas Association Pamphlet...

2011-07-01

359

29 CFR 1910.101 - Compressed gases (general requirements).  

Code of Federal Regulations, 2014 CFR

...1910.6. (b) Compressed gases. The in-plant handling...utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or motor vehicle cargo tanks shall be in accordance with Compressed Gas Association Pamphlet...

2014-07-01

360

41 CFR 50-204.70 - Compressed gases.  

Code of Federal Regulations, 2013 CFR

...50-204.70 Compressed gases. The in-plant handling...utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or motor vehicle cargo tanks shall be in accordance with Compressed Gas Association Pamphlet...

2013-07-01

361

29 CFR 1910.101 - Compressed gases (general requirements).  

Code of Federal Regulations, 2010 CFR

...1910.6. (b) Compressed gases. The in-plant handling...utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or motor vehicle cargo tanks shall be in accordance with Compressed Gas Association Pamphlet...

2010-07-01

362

41 CFR 50-204.70 - Compressed gases.  

Code of Federal Regulations, 2014 CFR

...50-204.70 Compressed gases. The in-plant handling...utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or motor vehicle cargo tanks shall be in accordance with Compressed Gas Association Pamphlet...

2014-07-01

363

29 CFR 1910.101 - Compressed gases (general requirements).  

Code of Federal Regulations, 2011 CFR

...1910.6. (b) Compressed gases. The in-plant handling...utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or motor vehicle cargo tanks shall be in accordance with Compressed Gas Association Pamphlet...

2011-07-01

364

41 CFR 50-204.70 - Compressed gases.  

Code of Federal Regulations, 2010 CFR

...50-204.70 Compressed gases. The in-plant handling...utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or motor vehicle cargo tanks shall be in accordance with Compressed Gas Association Pamphlet...

2010-07-01

365

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

366

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

367

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

368

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

369

49 CFR 229.43 - Exhaust and battery gases.  

Code of Federal Regulations, 2014 CFR

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

2014-10-01

370

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

371

THE RADIATION CHEMISTRY OF COAL IN VARIOUS ATMOSPHERES  

Microsoft Academic Search

The radiation chemistry of selected bituminous coals and the reactions ; of the coals with various gases in the presence of radiation were studied under ; static conditions. Speecial attention was given to radiative oxidation, which ; had been reported to produce beneficial Geiseler fluidity changes with some of ; the coals. Samples were prepared by introducing measured quantities of

A. Weinstein; P. L. Jr. Walker

1960-01-01

372

Method for enhancing microbial utilization rates of gases using perfluorocarbons  

DOEpatents

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

Turick, C.E.

1997-06-10

373

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

374

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

NASA Technical Reports Server (NTRS)

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

Gustincic, J. J. (inventor)

1981-01-01

375

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

376

Measuring the Isotopic Composition of Solar Wind Noble Gases  

E-print Network

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

377

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

378

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

379

Degenerate quantum gases with spin-orbit coupling: a review  

NASA Astrophysics Data System (ADS)

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

Zhai, Hui

2015-02-01

380

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

PubMed

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

Zhai, Hui

2015-02-01

381

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

382

bromine-containing source gases during EASOE  

NASA Astrophysics Data System (ADS)

Vertical profiles of CBrClF2 (Halon-1211), CBrF3 (Halon-1301) and methyl bromide (CH3Br) were measured during EASOE by means of cryogenic sampling and subsequent GC-analyses. Three flights of the MPAE balloon-borne sampler were carried out on January 18, February 6 and March 20, 1992, from Kiruna/Sweden. Stratospheric falloff rates of these substances, which constitute the dominant source of organically bound bromine in the atmosphere, were found, like those of other source gases measured during EASOE, to be considerably larger than those observed at midlatitudes. Total BrOx released from the three source gases was found to increase from about zero at 8 km to 11.4 pptV at 19 km altitude.

Fabian, Peter; Borchers, Reinhard; Kourtidis, Kostas

1994-06-01

383

Anesthetic gases and occupationally exposed workers.  

PubMed

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

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

2014-01-01

384

Equation of state for detonation product gases  

NASA Astrophysics Data System (ADS)

Based on the empirical linear relationship between detonation velocity and loading density, an approximate description for the Chapman-Jouguet (CJ) state for detonation product gases has been presented. Assuming that the Grüneisen parameter is a function only of volume, we obtained the Grüneisen parameter along CJ states. Thermodynamic identity between the Grüneisen parameter and another non-dimensional material parameter R used in the Rice-Walsh type equation of state introduced by Wu and Jing can be used to derive the enthalpy-pressure-volume equation of state for detonation gases. Behavior of this parameter R as a function of pressure is calculated and revealed that their change with pressure is very gradual and seems to approach a finite value with decreasing pressure. Release isentropes from CJ states of several initial density detonation of PETN is shown.

Nagayama, K.; Kubota, S.

2014-05-01

385

In Situ Imaging of Atomic Quantum Gases  

NASA Astrophysics Data System (ADS)

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

Hung, Chen-Lung; Chin, Cheng

2015-09-01

386

Possible cometary origin of heavy noble gases in the atmospheres of Venus, Earth and Mars  

PubMed

Models that trace the origin of noble gases in the atmospheres of the terrestrial planets (Venus, Earth and Mars) to the 'planetary component' in chondritic meteorites confront several problems. The 'missing' xenon in the atmospheres of Mars and Earth is one of the most obvious; this gas is not hidden or trapped in surface materials. On Venus, the absolute abundances of neon and argon per gram of rock are higher even than those in carbonaceous chondrites, whereas the relative abundances of argon and krypton are closer to solar than to chondritic values (there is only an upper limit on xenon). Pepin has developed a model that emphasizes hydrodynamic escape of early, massive hydrogen atmospheres to explain the abundances and isotope ratios of noble gases on all three planets. We have previously suggested that the unusual abundances of heavy noble gases on Venus might be explained by the impact of a low-temperature comet. Further consideration of the probable history of the martian atmosphere, the noble-gas data from the (Mars-derived) SNC meteorites and laboratory experiments on the trapping of noble gases in ice lead us to propose here that the noble gases in the atmospheres of all of the terrestrial planets are dominated by a mixture of an internal component and contribution from impacting icy planetesimals (comets). If true, this hypothesis illustrates the importance of impacts in determining the volatile inventories of these planets. PMID:11536499

Owen, T; Bar-Nun, A; Kleinfeld, I

1992-07-01

387

Method for introduction of gases into microspheres  

DOEpatents

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

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

1981-01-01

388

Splitting of inviscid fluxes for real gases  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

389

Gases : GasRxnVolumes (10 Variations)  

NSDL National Science Digital Library

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

390

Basic studies of gases for fast switches  

NASA Astrophysics Data System (ADS)

Desirable electron attachment and electron drift characteristics of gases for possible use in diffuse-discharge switches are indicated. Gas mixtures for possible use in externally sustained (e-beam) diffuse-discharge switches are suggested on the basis of electron attachment rate constants and electron drift velocities measured as a function of the density-normalized electric field E/N. Of particular promise are mixtures of Ar and C3F8.

Christophorou, L. G.; Hunter, S. R.

1985-11-01

391

Basic studies of gases for fast switches  

NASA Astrophysics Data System (ADS)

Desirable electron attachment and electron drift characteristics of gases for possible use in diffuse discharge switches are indicated. Gas mixtures for possible use in externally sustained (e-beam) diffuse discharge switches are suggested on the basis of electron attachment rate constants and electron drift velocities measured as a function of the density-normalized electric field E/N. Of particular promise are mixtures of Ar and C3F8.

Christophorou, L. G.; Hunter, S. R.

1985-01-01

392

Rare gases, water, and carbon in kaersutites  

Microsoft Academic Search

Kaersutites from Kakanui, New Zealand and from three localities in the southwestern United States have been analyzed for rare gases, water and carbon to investigate the volatile signature of the sub-continental mantle. This study does not confirm the high 3He\\/4He and 21Ne\\/22Ne ratios reported by Saito et al. [1] for the Kakanui kaersutite. Instead, a 3He\\/4He ratio of 6 RA

Robert J. Poreda; Asish R. Basu

1984-01-01

393

Scanning electron microscopy of cold gases  

E-print Network

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

Santra, Bodhaditya

2015-01-01

394

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

395

Current fluctuations in stochastic lattice gases.  

PubMed

We study current fluctuations in lattice gases in the macroscopic limit extending the dynamic approach for density fluctuations developed in previous articles. More precisely, we establish a large deviation theory for the space-time fluctuations of the empirical current which include the previous results. We then estimate the probability of a fluctuation of the average current over a large time interval. It turns out that recent results by Bodineau and Derrida [Phys. Rev. Lett. 92, 180601 (2004)

Bertini, L; De Sole, A; Gabrielli, D; Jona-Lasinio, G; Landim, C

2005-01-28

396

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

397

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

398

Method for introduction of gases into microspheres  

SciTech Connect

A method for producing small hollow glass spheres filled with a gas by introduction of the gas during formation of the hollow glass spheres. Hollow glass microspheres having a diameter up to about 500 mu with both thin walls (0.5 to 4 mu ) and thick walls (5 to 20 mu ) that contain various fill gases, such as ar, kr, xe , br, dt, h2, d2, he, n2, ne, co2, etc. In the interior thereof, can be produced by the diffusion of the fill gas or gases into the microsphere during the formation thereof from a liquid droplet of glass-forming solution. This is accomplished by filling at least a portion of the multiple-zone drop-furnace used in producing hollow microspheres with the gas or gases of interest, and then taking advantage of the high rate of gaseous diffusion of the fill gas through the wall of the gel membrane before it transforms into a glass microsphere as it is processed in the multiple-zone furnace. Almost any gas can be introduced into the inner cavity of a glass microsphere by this method during the formation of the microsphere provided that the gas is diffused into the gel membrane or microsphere prior to its transformation into glass. The process of this invention provides a significant savings of time and related expense of filling glass microspheres with various gases. For example, the time for filling a glass microballoon with 1 atmosphere of dt is reduced from about two hours to a few seconds.

Hendricks, C.D.; Koo, J.C.; Rosencwaig, A.

1981-03-24

399

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

400

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

SciTech Connect

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

Prather, Michael J. [UCI

2014-11-07

401

Treatment of flue gas containing noxious gases  

SciTech Connect

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

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

1987-07-21

402

ENERGY RELAXATION OF HELIUM ATOMS IN ASTROPHYSICAL GASES  

SciTech Connect

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

Lewkow, N. R.; Kharchenko, V. [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Zhang, P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2012-09-01

403

Nadir Sounding of Carbon Gases using SCIAMACHY Near Infrared Channels  

NASA Astrophysics Data System (ADS)

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

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

404

Growth Responses of Neurospora crassa to Increased Partial Pressures of the Noble Gases and Nitrogen  

PubMed Central

Buchheit, R. G. (Union Carbide Corp., Tonawanda, N.Y.), H. R. Schreiner, and G. F. Doebbler. Growth responses of Neurospora crassa to increased partial pressures of the noble gases and nitrogen. J. Bacteriol. 91:622–627. 1966.—Growth rate of the fungus Neurospora crassa depends in part on the nature of metabolically “inert gas” present in its environment. At high partial pressures, the noble gas elements (helium, neon, argon, krypton, and xenon) inhibit growth in the order: Xe > Kr> Ar ? Ne ? He. Nitrogen (N2) closely resembles He in inhibitory effectiveness. Partial pressures required for 50% inhibition of growth were: Xe (0.8 atm), Kr (1.6 atm), Ar (3.8 atm), Ne (35 atm), and He (? 300 atm). With respect to inhibition of growth, the noble gases and N2 differ qualitatively and quantitatively from the order of effectiveness found with other biological effects, i.e., narcosis, inhibition of insect development, depression of O2-dependent radiation sensitivity, and effects on tissue-slice glycolysis and respiration. Partial pressures giving 50% inhibition of N. crassa growth parallel various physical properties (i.e., solubilities, solubility ratios, etc.) of the noble gases. Linear correlation of 50% inhibition pressures to the polarizability and of the logarithm of pressure to the first and second ionization potentials suggests the involvement of weak intermolecular interactions or charge-transfer in the biological activity of the noble gases. PMID:5883104

Buchheit, R. G.; Schreiner, H. R.; Doebbler, G. F.

1966-01-01

405

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

SciTech Connect

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

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

1998-07-01

406

Radiative forcing caused by rocket engine emissions  

NASA Astrophysics Data System (ADS)

Space transportation plays an important and growing role in Earth's economic system. Rockets uniquely emit gases and particles directly into the middle and upper atmosphere where exhaust from hundreds of launches accumulates, changing atmospheric radiation patterns. The instantaneous radiative forcing (RF) caused by major rocket engine emissions CO2, H2O, black carbon (BC), and Al2O3 (alumina) is estimated. Rocket CO2 and H2O emissions do not produce significant RF. BC and alumina emissions, under some scenarios, have the potential to produce significant RF. Absorption of solar flux by BC is likely the main RF source from rocket launches. In a new finding, alumina particles, previously thought to cool the Earth by scattering solar flux back to space, absorb outgoing terrestrial longwave radiation, resulting in net positive RF. With the caveat that BC and alumina microphysics are poorly constrained, we find that the present-day RF from rocket launches equals 16 ± 8 mW m-2. The relative contributions from BC, alumina, and H2O are 70%, 28%, and 2%. respectively. The pace of rocket launches is predicted to grow and space transport RF could become comparable to global aviation RF in coming decades. Improved understanding of rocket emission RF requires more sophisticated modeling and improved data describing particle microphysics.

Ross, Martin N.; Sheaffer, Patti M.

2014-04-01

407

Seeded optical breakdown of molecular and noble gases  

NASA Astrophysics Data System (ADS)

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

Polynkin, Pavel; Scheller, Maik; Moloney, Jerome V.

2012-07-01

408

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

409

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

410

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

411

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

412

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

Code of Federal Regulations, 2014 CFR

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

2014-10-01

413

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

SciTech Connect

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

Bartnik, A.; Fiedorowicz, H.; Wachulak, P. [Institute of Optoelectronics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland)

2014-07-15

414

Emissions Of Greenhouse Gases From Rice Agriculture  

SciTech Connect

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

M. Aslam K. Khalil

2009-07-16

415

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

416

Spin-imbalanced quasi-two-dimensional fermi gases.  

PubMed

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

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

2015-03-20

417

Photosensitive dopants for liquid noble gases  

DOEpatents

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

Anderson, David F. (Wheaton, IL)

1988-01-01

418

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

PubMed

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. PMID:20646920

Friedrich, Elena; Trois, Cristina

2010-11-01

419

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

420

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

421

Adsorption of Gases on Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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

Mbaye, Mamadou Thiao

422

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

423

Traveling dark solitons in superfluid Fermi gases  

SciTech Connect

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

Liao Renyuan; Brand, Joachim [New Zealand Institute for Advanced Study and Centre for Theoretical Chemistry and Physics, Massey University, Private Bag 102904 NSMC, Auckland 0745 (New Zealand)

2011-04-15

424

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

425

Method for detecting trace impurities in gases  

DOEpatents

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

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

1981-01-01

426

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

427

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

428

Heat conduction in relativistic neutral gases revisited  

E-print Network

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

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

2010-09-30

429

Shock waves, implosions and dusty gases  

NASA Astrophysics Data System (ADS)

Progress in analytical, numerical, and experimental research on shock waves, implosions, and dusty gases at the University of Toronto Institute for Aerospace Studies is reviewed. Solutions for the laminar compressible dusty-gas boundary layer over a semi-infinite flat plate were obtained, as well as that for the complementary boundary layer induced by a moving shock in a dusty-gas tube. Numerical studies of weak spherical N-waves in air are continuing. Research on the effects of shock-wave compression from implosions on chemical reaction and diffusion rates in solids is completed, as is analytical and experimental study of pseudo-stationary oblique shock wave reflections.

Glass, I. I.; Zhang, D.-L.; Kaca, J.

430

Remote Sensing of Greenhouse Gases and Their Sources and Sinks  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

431

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

432

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

NASA Astrophysics Data System (ADS)

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

Levinsen, Mogens

2011-03-01

433

[Desulfurization of fuel gases]. Executive summary  

SciTech Connect

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

Not Available

1991-12-15

434

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

435

Gases Inside the Earth / Muddy Waters  

NSDL National Science Digital Library

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

436

Formation and development dynamics of femtosecond laser microplasma in gases  

SciTech Connect

We report our experimental investigations of the formation and development dynamics of laser plasma produced in gas microvolumes (microplasma) upon multiple ionisation by tightly focused (to a spot 2-3 {mu}m in diameter) high-intensity (up to {approx}10{sup 17} W cm{sup -2}) femtosecond pulses of a Ti:sapphire laser ({tau}{sub p} {approx_equal} 130 fs, {lambda} = 800 nm). Precision interferometric measurements (with a spatial resolution of {approx}1.5 {mu}m) were made of the spatiotemporal distribution of the refractive index and electron density in the microplasmas of the air and helium immediately during the action of the exciting femtosecond laser pulse and at the initial stage of free plasma expansion. The microplasma formation was shown to occur as a result of almost complete (up to bare nuclei) ionisation of the initial gas. For the first time the spectral continuum and the dynamics of spectral line formation in the UV and visible spectral ranges were investigated with a picosecond time resolution for the femtosecond laser-produced microplasmas of the air, N{sub 2}, Ar, and He at normal conditions. For the first time the generation of the second (even) laser radiation harmonic was recorded in a femtosecond subcritical-density plasma of gases. (special issue devoted to the 90th anniversary of a.m. prokhorov)

Bukin, V V; Vorob'ev, Nikolai S; Garnov, Sergei V; Konov, Vitalii I; Lozovoi, V I; Malyutin, A A; Shchelev, M Ya; Yatskovskii, I S, E-mail: vbkn@kapella.gpi.r, E-mail: vor@kapella.gpi.r, E-mail: garnov@kapella.gpi.r, E-mail: vik@nsc.gpi.r, E-mail: evi@ran.gpi.r, E-mail: amal@kapella.gpi.r, E-mail: m.schelev@ran.gpi.r, E-mail: yatskov@kapella.gpi.r [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2006-07-31

437

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

438

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

439

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

440

Chapter 4 The Gaseous State Chemistry of Gases  

E-print Network

Chapter 4 The Gaseous State NO2 #12;AIR #12;Chemistry of Gases SO3 .. corrosive gas SO2...burning) ~1760 Charle The definition of the Temperature All gases expand with increasing temperature by the same extent. t = c [(V/V0)-1] for all gases 1802 Gay-Lussac reproted c of 267 oC later refined to be c = 273

Ihee, Hyotcherl

441

Quantum control and measurement of spins in laser cooled gases  

NASA Astrophysics Data System (ADS)

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

Deutsch, Ivan

2012-10-01

442

Emissions of some trace gases from biomass fires  

NASA Astrophysics Data System (ADS)

Airborne measurements of 13 trace gases from seven forest fires in North America are used to determine their average emission factors. The emission factors are then used to estimate the contributions of biomass burning to the worldwide fluxes of these gases. The estimate for NH3 (˜7 Tg N yr-1) is about 50% of the global emissions of this gas. Combined NH3 and ? emissions from biomass burning could be the most important component of the NH3 cycle. N2O from biomass burning (˜ 2 Tg N yr-1) is also significant worldwide. The estimate for NOx from biomass burning worldwide (˜ 19 Tg N yr-1), which is greater than previous estimates, is comparable to emissions from fossil fuel combustion. The estimate of the global flux of F12 (CF2Cl2) from biomass burning based on the complete data set (˜0.2 Tg yr-1) is ˜50% of the total global emission of F12. However, this estimate is strongly influenced by a very high emission of F12 from a fire in the Los Angeles Basin. Disregarding this fire yields a global flux of 0.06 Tg yr-1 (˜15% of total global emissions). The high emissions of NOx and F12 are due in whole or part to the resuspension of previously deposited pollutants. Since this can be the only source of F12 in the smoke from fires, deposition may be a significant sink for F12. Our estimate for NOx emissions from biomass burning in the South Coast Air Basin of California is much greater than previous estimates.

Hegg, Dean A.; Radke, Lawrence F.; Hobbs, Peter V.; Rasmussen, Rei A.; Riggan, Philip J.

1990-04-01

443

Determination of some thermodynamic characteristics in an exhaust gases supercharger  

NASA Astrophysics Data System (ADS)

The pressure and temperature characteristics of gases at the intake of an exhaust gases supercharger feeding an internal combustion reciprocating engine are determined in a rigorous way from the energy point of view. The Rateau system utilizing only the gases which go out of the cylinder spontaneously, and the total system which utilizes all the gases going out of the cylinder are considered. Diagrams showing the thermodynamic characteristics of the compressor, of the engine, and of the turbine are given. Results show that the superchargers can be used at altitudes other than sea level.

Casci, C.

444

Rare gas isotopic compositions in natural gases of Japan  

NASA Astrophysics Data System (ADS)

Isotopic and elemental compositions of rare gases in various types of gas samples collected in the Japanese Islands were investigated. Excess 3He was found in most samples. Many samples showed a regionally uniform high 3He/ 4He ratio of about 7 times the atmospheric ratio. The He concentrations varied from 0.6 to 1800 ppm, and they were low in CO 2-rich gases and high in N 2-rich gases. Ne isotopic deviations from the atmospheric Ne were detected in most volcanic gases. The deviations and the elemental abundance patterns in volcanic gases can be explained by a mixing between two components, one is mass fractionated rare gases and the other is isotopically atmospheric and is enriched in heavy rare gas elements. Ar was a mixture of mass fractionated Ar, atmospheric Ar and radiogenic Ar, and the contribution of radiogenic 40Ar was small in all samples. Except for He, elemental abundance patterns were progressively enriched in the heavier rare gases relative to the atmosphere. Several samples were highly enriched in Kr and Xe relative to the abundance pattern of dissolution equilibrium of atmospheric rare gases in water. The component which is highly enriched in heavy rare gases may be released from sedimentary materials in the crust.

Nagao, Keisuke; Takaoka, Nobuo; Matsubayashi, Osamu

1981-04-01

445

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

446

Are Liquids Molten Solids or Condensed Gases?  

NASA Astrophysics Data System (ADS)

Introduction The Radiant Vector R Thermal Radiation Forces ƒth Heat Propagation in Liquids The Experimental Situation Measurements of TRFs and Microgravity Relevance of the Problem Thermal Diffusion Direct Measurement of TRFs

Gaeta, F. S.; Peluso, F.; Albanese, C.; Mita, D. G.

447

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

448

The Oceanic Source of Trace Gases Now and in the Future  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

449

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

450

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

NASA Astrophysics Data System (ADS)

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 (NO x, CO and others) is an important greenhouse forcing term. In addition, the recognition of chlorofluorocarbons (CFCs) on stratospheric ozone and its climate effects linked chemistry and climate strongly. What is less recognized, however, is a comparably major global problem dealing with air pollution. Until about ten years ago, air pollution was thought to be just an urban or a local problem. But new data have revealed that air pollution is transported across continents and ocean basins due to fast long-range transport, resulting in trans-oceanic and trans-continental plumes of atmospheric brown clouds (ABCs) containing sub micron size particles, i.e., aerosols. ABCs intercept sunlight by absorbing as well as reflecting it, both of which lead to a large surface dimming. The dimming effect is enhanced further because aerosols may nucleate more cloud droplets, which makes the clouds reflect more solar radiation. The dimming has a surface cooling effect and decreases evaporation of moisture from the surface, thus slows down the hydrological cycle. On the other hand, absorption of solar radiation by black carbon and some organics increase atmospheric heating and tend to amplify greenhouse warming of the atmosphere. ABCs are concentrated in regional and mega-city hot spots. Long-range transport from these hot spots causes widespread plumes over the adjacent oceans. Such a pattern of regionally concentrated surface dimming and atmospheric solar heating, accompanied by widespread dimming over the oceans, gives rise to large regional effects. Only during the last decade, we have begun to comprehend the surprisingly large regional impacts. In S. Asia and N. Africa, the large north-south gradient in the ABC dimming has altered both the north-south gradients in sea surface temperatures and land-ocean contrast in surface temperatures, which in turn slow down the monsoon circulation and decrease rainfall over the continents. On the other hand, heating by black carbon warms the atmosphere at elevated levels from 2 to 6 km, where most tropical glaciers are located, thus strengthening the effect of GHGs on retreat of snow packs and glaciers in the Hindu Kush-Himalaya-Tibetan glaciers. Globally, the surface cooling effect of ABCs may have masked as much 47% of the global warming by greenhouse gases, with an uncertainty range of 20-80%. This presents a dilemma since efforts to curb air pollution may unmask the ABC cooling effect and enhance the surface warming. Thus efforts to reduce GHGs and air pollution should be done under one common framework. The uncertainties in our understanding of the ABC effects are large, but we are discovering new ways in which human activities are changing the climate and the environment.

Ramanathan, V.; Feng, Y.

451

Mantle-derived noble gases in natural gases from Songliao Basin, China  

NASA Astrophysics Data System (ADS)

Abundances and isotopic compositions of noble gases have been measured in six natural gas samples (CO 2 and CH 4-rich) from the Songliao Basin, Jilin Province, in northeastern China. The samples contain noble gases of mantle origin. The 3He/4He ratio reaches 5.0 times the atmospheric ratio. In a three-isotope plot of neon, the 20Ne/22Ne (up to 10.9) and 21Ne/22Ne (up to 0.051) ratios make a positive correlation array together with natural gases from other continental areas. Compared with a correlation band for MORB, the natural gases have a lower slope with more nucleogenic 21Ne. The natural gas samples contain radiogenic argon with 40Ar/36Ar ratios up to 7700. A positive correlation between 40Ar/36Ar and 20Ne/22Ne ratios indicates occurrence of mantle-derived Ar. Slight excess of 38Ar can be attributed to a nuclear reaction like 35C1 (?, p) 38 Ar. Apparent excesses of 1292'Xe, 132-136Xe are recognized in four samples. The excess of 129Xe (up to 3%) can be attributed to a decay of extinct 129I. Excess 132-136Xe is not large enough to determine if the origin of the excess is 238U or 244Pu. Anomaly in 129Xe/130Xe ratio is correlated with that of 136Xe/130Xe. The isotopic features of the natural gases with radiogenic 4He and nucleogenic 21Ne can be produced within the crust. Alternatively, they may reflect the geochemical features of the subcontinental mantle which has been enriched in U, Th. We can not distinguish the two possibilities. However, a natural gas from another basin in eastern China with a different reservoir age contains mantle derived neon which falls on the neon correlation line formed by the samples from the Songliao Basin. This consistency suggests that the isotopic features of the natural gases aren't necessarily ascribable to surface contamination of radiogenic and nucleogenic isotopes.

Xu, Sheng; Nakai, Shun'ichi; Wakita, Hiroshi; Wang, Xianbin

1995-11-01

452

Trends In Positron Scattering From Noble Gases  

NASA Astrophysics Data System (ADS)

We have a program of low energy (< 100 eV), high resolution (~ 60 meV), positron scattering from atoms and molecules which is being facilitated by a high-flux, trapbased positron beamline facility at the Australian National University (Sullivan et al. 2008). The positron beam utilised is a pulsed beam which operates at about 100 Hz. A typical pulse will contain about 1000 positrons. For noble gases, our goals range from establishing "benchmarks" for positron scattering cross sections, to investigation of threshold effects in processes such as positronium formation and ionization. This paper will present examples of trends observed in a number of scattering processes in He, Ne, Ar, Kr and Xe. The project includes investigations of the - elastic cross sections - positronium formation cross sections - total cross sections Where possible the current experimental results will be compared with the best available theoretical calculations and other experimental data from literature.

Jones, A.; Caradonna, P.; Machacek, P.; Makochekanwa, C.; Slaughter, D.; McEachran, R.; Sullivan J.; Buckman, S.

2010-07-01