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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

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

NASA Astrophysics Data System (ADS)

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

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

2000-07-01

4

Infrared Radiative Heat Transfer in Nongray Gases.  

National Technical Information Service (NTIS)

The object of this investigation was to study various approximate methods of analyzing infrared radiative heat transfer in nongray nonisothermal gases. For this purpose, a very simple physical system was chosen consisting of a gas bounded by two infinite ...

R. D. Cess P. Mighdoll S. N. Tiwari

1967-01-01

5

Infrared Radiative Heat Transfer in Nongray Gases.  

National Technical Information Service (NTIS)

The object of the investigation was to study various approximate methods of analyzing infrared radiative heat transfer in nongray nonisothermal gases. For this purpose, a very simple physical system was chosen, and this consists of a gas bounded by two in...

R. D. Cess P. Mighdoll S. N. Tiwari

1967-01-01

6

A Thermophysical Property Databank for Technically Important Gases and Liquids  

Microsoft Academic Search

A thermophysical property databank for technically important gases and liquids has been created. It provides users with data for nearly 30 substances: monatomic and diatomic gases, air, water and steam, carbon dioxide, ammonia, some hydrocarbons, and refrigerants. The coefficients of the equations of state and equations for calculating transport properties, the ideal-gas functions, the saturated vapor pressure, and the melting

A. A. Vasserman; A. G. Slynko; S. V. Bodyul; Yu. V. Gondarenko; E. S. Bodyul

2001-01-01

7

Radiative forcings and global warming potentials of 39 greenhouse gases  

Microsoft Academic Search

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

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

2000-01-01

8

Role of tropospheric gases in the absorption of UV radiation  

Microsoft Academic Search

The influence of different tropospheric gases on the attenuation of UV radiation at the Earth’s surface is considered. In order to estimate their influence it is suggested to use parameter AS , which characterizes the sensitivity of UV radiation to the variation in the gas content per 1 matm · cm. Based on the model calculation data, the estimates of

N. E. Chubarova

2006-01-01

9

Radiation interactions in high-pressure gases  

Microsoft Academic Search

This article is on basic radiation interaction processes in dense fluids and on interphase studies aiming at the interfacing of knowledge on radiation interaction processes in the gaseous and the liquid state of matter. It is specifically focused on the effect of the density and nature of the medium on electron production in irradiated fluids and on the state, energy,

Christophorou

1990-01-01

10

Transient radiative energy transfer in nongray gases  

NASA Astrophysics Data System (ADS)

A general formulation is presented to investigate the transient radiative interaction in nongray absorbing-emitting species between two parallel plates. Special attention is directed to investigate the radiative interaction in a system initially at a uniform reference temperature where suddenly the temperature of the bottom plate is reduced to a lower but constant temperature. The interaction is considered for the case of radiative equilibrium as well as for combined radiation and conduction. General as well as limiting forms of the govering equations are presented and solutions are obtained numerically by employing the method of variation of parameters. Specific results are obtained for CO, CO2, H2O, and OH. The information on species H2O and OH is of special interest for the proposed scramjet engine application. The results demonstrate the relative ability of different species for radiative interactions.

Tiwari, S. N.; Singh, D. J.; Kumar, A.

1987-01-01

11

Absorption of Thermal Radiation by Layers of Condensed Gases.  

National Technical Information Service (NTIS)

The measurements of infrared radiation absorption by layers of condensed gases showed that layers of N sub 2 and Ar are essentially transparent in the region of long wavelengths between 5 and 40 mu m, and that layers of H sub 2 and especially H sub 2 O st...

S. F. Grishin E. Y. Grishina V. A. Kovalenko R. V. Mimin V. Y. Chernyshenko

1977-01-01

12

Research on the Photon Absorption Processes of Gases Important in the Upper Atmosphere.  

National Technical Information Service (NTIS)

The results of investigations into the absorption processes of gases important in upper atmosphere chemistry and physics are presented. The principle region studied in the vacuum ultraviolet at wavelengths less than 3000 A. Methods of producing the OH rad...

J. L. Roebber

1970-01-01

13

Unusual Atomic Radiation Phenomena in Gases and Plasmas  

NASA Astrophysics Data System (ADS)

Basic concepts such as the uncertainty principle, thermodynamic equilibrium, and quantum interference are used to analyze new phenomena in plasmas and atomic gases. For example, an atomic configuration with one allowed transition and one forbidden, exhibits an interesting effect under the influence of plasma microfield [1]. If a laser pulse or an electron beam excites such atoms in a plasma, the core and the wings of the line of the atomic spectrum are polarized differently. A second example is three-level atoms in thermodynamic equilibrium with a photon gas [2]. To describe thermodynamic equilibirum, it is not sufficient to specify only Boltzmann exponents, which are diagonal elements of the density matrix. In fact, the non-diagonal elements become non-zero as a result of quantum interference. This interference exists even in thermodynamic equilibrium and leads to a modified radiation spectrum, which vanishes at one frequency, but exhibits a two-fold increase in the intensity of the recently discovered red wing [3]. For certain conditions, quantum interference suppresses spontaneous emission over a range of frequencies [4] as opposed to suppression at only one frequency [5]. [1] V. I. Savchenko and N. J. Fisch, Phys. Rev. Lett. 79, 669 (1997) [2] V. I. Savchenko, N. J. Fisch, A. A. Panteleev and A. N. Starostin, submitted to Phys. Rev. A [3] Y. K. Zemtsov and A. N. Starostin, JETP 76, 186 (1993) [4] V. I. Savchenko, A. A. Panteleev, and A. N. Starostin, in Proceedings on the 13-th International Conference on Laser Interaction and Related Plasma Phenomena (AIP Press, New York, 1997) [5] U. Fano, Phys. Rev. A 124, 1866 (1961); S. Y. Zhu et al., Phys. Rev. A 52, 710 (1995)

Savchenko, Vladislav I.

1998-11-01

14

Study of Multi-Dimensional Radiative Energy Transfer in Molecular Gases.  

National Technical Information Service (NTIS)

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 corre...

J. Liu S. N. Tiwari

1993-01-01

15

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

NASA Astrophysics Data System (ADS)

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

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

2006-10-01

16

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

17

Condition of Retrieving Vertical Column Density of Atmospheric Pollution Gases by Using Scattered Solar Radiation  

NASA Astrophysics Data System (ADS)

We present a method to monitor the vertical column density (VCD) of atmospheric pollution gases by using the scattered solar radiation. The necessary condition of capturing the useful scattered solar radiation is achieved. The condition is only dependent on the solar elevation angle, while independent of the solar azimuth angle, which could greatly simply the capturing equipment and procedure. Under the condition, the VCD of tropospheric NO2 in Chengdu, China is retrieved from the scattered solar radiation, which is close to that from the direct solar radiation.

Zuo, Hao-Yi; Luo, Shi-Rong

2009-01-01

18

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

PubMed

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

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

2012-04-04

19

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.

2012-01-01

20

Near Threshold Polarization of Line Radiation From Noble Gases  

Microsoft Academic Search

Line radiation from atoms or ions excited with asial symmetry by electron beams is generally linearly polarized. At the excitation threshold, this polarization has a kinematically required value resulting from exclusive prodution of orbital magnetic sublevels with m_l=0. In the large majority of cases involving group I and II atoms or ions the polarization falls to less than half this

K. W. Trantham; M. E. Johnston; T. J. Gay

1996-01-01

21

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

NASA Astrophysics Data System (ADS)

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

Janetos, A. C.

2007-12-01

22

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

NASA Astrophysics Data System (ADS)

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

Richter, Andreas; Wagner, Thomas

23

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

2009-09-11

24

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

25

Investigations of laser-driven radiative blast waves in clustered gases  

NASA Astrophysics Data System (ADS)

Radiative blast waves can be created by focusing intense laser pulses into highly absorbing clustered gases. By considering the plasma conditions these shocks can be categorized as optically thin radiative shocks, a regime of particular interest for laboratory astrophysics experiments. A periodic spatial modulation is introduced to the shock front in order to investigate instability and shock collisions. Hydrodynamic simulations are presented which are in qualitative agreement with the experimental results. A technique to perform a single shot measurement of the entire shock trajectory and the possibility to detect oscillations in the shock velocity is discussed.

Symes, D. R.; Hohenberger, M.; Lazarus, J.; Osterhoff, J.; Moore, A. S.; Fäustlin, R. R.; Edens, A. D.; Doyle, H. W.; Carley, R. E.; Marocchino, A.; Chittenden, J. P.; Bernstein, A. C.; Gumbrell, E. T.; Dunne, Mike; Smith, R. A.; Ditmire, T.

2010-06-01

26

Planetary Formation and Evolution Revealed with a Saturn Entry Probe: The Importance of Noble Gases  

Microsoft Academic Search

The determination of Saturn's atmospheric noble gas abundances are critical to understanding the formation and evolution of Saturn, and giant planets in general. These measurements can only be performed with an entry probe. A Saturn probe will address whether enhancement in heavy noble gases, as was found in Jupiter, are a general feature of giant planets, and their ratios will

Jonathan J. Fortney; Kevin Zahnle; Isabelle Baraffe; Adam Burrows; Sarah E. Dodson-Robinson; Gilles Chabrier; Tristan Guillot; Ravit Helled; Franck Hersant; William B. Hubbard; Jack J. Lissauer; Mark S. Marley

2009-01-01

27

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

28

Studying radiative shocks using laser driven blast waves in clustered gases  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

29

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

30

Health risks by bromomethane and other toxic gases in import cargo ship containers.  

PubMed

Containers are increasingly used for the worldwide transport of all kinds of goods. Consistent with national and international regulations on pest controls, a growing proportion of these containers undergoes fumigation. Frequently, the prescribed labelling is missing. According to literature, this situation may lead to accidents and represents a significant health risk to dock workers, inspectors and custom workers. Furthermore, warehouse workers and even consumers may come in contact with these toxic fumigants. Presented measurement data underline this health risks due to bromomethane but also due to other fumigants and, surprisingly, due to further noxious gases. So far, no routine method for sensitive and specific measurements on the spot has been available. The consequences of container fumigation should always be carefully weighed up, and alternatives to pesticides, e.g. heat treatment or atmospheres with reduced oxygen and for high CO2 concentrations should be considered. In addition, stringent international controls as well as sanctions if IMO's "Recommendations on the safe use of pesticides in ships" are disregarded are required. PMID:17312693

Baur, Xaver; Yu, Fang; Poschadel, Bernd; Veldman, Wim; Vos, Tosca Knol-de

2006-01-01

31

Generation of coherent radiation in the XUV by fifth- and seventh-order frequency conversion in rare gases  

Microsoft Academic Search

Results of experimental studies of the generation of coherent radiation in the XUV by high order optical nonlinearities in the rare gases are described. Fifth- and seventh-harmonic conversion and six wave mixing of harmonic pulses from an Nd:YAG laser were used to produce radiation at several discrete wavelengths between 38 and 76 nm. Experimental measurements of fifth-harmonic conversion of pump

J. Reintjes; R. C. Eckardt; C.-Y. She

1978-01-01

32

Generation of coherent radiation in XUV by fifth- and seventh-order frequency conversion in rare gases  

Microsoft Academic Search

Results of experimental studies of the generation of coherent radiation in the XUV by high order optical nonlinearities in the rare gases are described. Fifth- and seventh-harmonic conversion and six wave mixing of harmonic pulses from an Nd:YAG laser were used to produce radiation at several discrete wavelengths between 38 and 76 nm. Experimental measurements of fifth-haxmonic conversion of pump

JOHN REINTJES; Chiao-Yao She; R. C. Eckardt

1978-01-01

33

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

34

Radiation-induced cell death: importance of lysosomal destabilization.  

PubMed

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

Persson, H Lennart; Kurz, Tino; Eaton, John W; Brunk, Ulf T

2005-08-01

35

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

2009-10-26

36

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

NASA Astrophysics Data System (ADS)

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

Talbot, Robert; Mao, Huiting; Sive, Barkley

2005-05-01

37

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

38

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

39

Solar Radiation Output Indices of Importance for Exospheric Properties  

NASA Astrophysics Data System (ADS)

The solar output in a broad spectral range, from X-rays to ultraviolet, significantly influences the distribution of hydrogen (H) atoms in the exosphere. All three populations—ballistic, satellite, and escaping atoms—are affected by solar radiation as it modifies the effective altitude and temperature of the exobase, controls to a large degree the dynamics of satellite atoms by radiation pressure, and contributes to atom losses. The Two Wide-angle imaging Neutral Atom Spectrometers (TWINS) mission stereoscopically images the magnetosphere in energetic neutral atom fluxes and additionally carries Lyman-alpha detectors (LADs) to investigate exospheric hydrogen. We use LAD measurements to obtain the global three-dimensional H distributions on a daily basis. The sequence of such distributions will enable studying of the exospheric response to the time-varying solar output. We show that the commonly used F10.7 index does not fully describe the solar conditions of importance to exospheric properties. We analyze the available indices F10.7, E10.7, S10.7, and Lyman-alpha which characterize the solar output from X-rays to ultraviolet. The characteristic times of processes governing atom injection, dynamics, and losses are different, which calls for the use of appropriate indices and their combinations. We discuss the available data sets, as well as the potential for study of exospheric response to variations in the solar output.

Bailey, J. J.; Gruntman, M.; Tobiska, W.

2010-12-01

40

The importance and unique aspects of radiation protection in medicine  

Microsoft Academic Search

Radiation protection in medicine has unique aspects and is an essential element of medical practice. Medical uses of radiation occur throughout the world, from large cities to rural clinics. It has been estimated that the number of medical procedures using radiation grew from about 1.7 billion in 1980 to almost 4 billion in 2007. In spite of these large numbers,

Ola Holmberg; Renate Czarwinski; Fred Mettler

2010-01-01

41

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

Microsoft Academic Search

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

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

2006-01-01

42

Long-term trends in concentrations of halocarbons and radiatively active trace gases in atlantic and european air masses monitored at mace head, Ireland from 1987–1994  

Microsoft Academic Search

Long-term trends in trace gas concentrations over the period 1987–1994 are reported here for air masses advected to the Mace Head monitoring station on the remote west coast of Ireland. The trace gases covered include the principal halocarbons: CFC-11, CFC-12, CFC-113, CCl4 and methyl chloroform; the radiatively active trace gases: carbon dioxide, methane, nitrous oxide and ozone; together with carbon

P. G. Simmonds; R. G. Derwent; A. McCulloch; S. O'Doherty; A. Gaudry

1996-01-01

43

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

44

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

2011-09-21

45

Atmospheric radiation  

SciTech Connect

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

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

1991-01-01

46

Theory of breakdown of molecular gases by laser radiation near a metal surface  

NASA Astrophysics Data System (ADS)

The threshold power of laser radiation is determined at which a low-threshold breakdown occurs in a molecular-gas atmosphere near a metal surface. The breakdown is regarded as a sufficiently pronounced transition from a state in which the electrons of the gas medium form due to diffusion from the heated surface to one in which they form due to volume ionization of the target vapor. Gas breakdown power (W) is calculated, and the results are found to agree with previous experimental data. Furthermore, the dependence of W on the focal spot radius is determined for niobium, molybdenum, tantalum, and tungsten surfaces.

Vorobev, V. S.; Khomkin, A. L.

1984-11-01

47

Noble Gases  

NASA Astrophysics Data System (ADS)

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

Podosek, F. A.

2003-12-01

48

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

49

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

50

Important step in radiation carcinogenesis may be inactivation of cellular genes  

SciTech Connect

The loss of genetic material may result in a predisposition to malignant disease. The best studied example is retinoblastoma where deletion or transcriptional inactivation of a specific gene is associated with the development of the tumor. When hereditary retinoblastoma patients are treated with radiation, the incidence of osteosarcoma within the treatment field is extremely high compared to other cancer patients treated with radiotherapy. These data, together with cytogenetic and molecular data on the development of acute non-lymphocytic leukemia secondary to radiotherapy and chemotherapy treatment suggest that radiation-induced deletions of critical DNA sequences may be an important event in radiation carcinogenesis. Therefore, we propose that radiation-induced tumors may result from deletion of tissue specific regulatory genes. Base alterations caused by radiation in dominantly transforming oncogenes may also contribute to radiation carcinogenesis.62 references.

Weichselbaum, R.R.; Beckett, M.A.; Diamond, A.A.

1989-01-01

51

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

52

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

53

MAX-DOAS measurements of atmospheric trace gases in Ny-Ålesund - Radiative transfer studies and their application  

Microsoft Academic Search

A new approach to derive tropospheric concentrations of some atmospheric trace gases from ground-based UV\\/vis measurements is described. The instrument, referred to as the MAX-DOAS, is based on the well-known UV\\/vis instruments, which use the sunlight scattered in the zenith sky as the light source and the method of Differential Optical Absorption Spectroscopy (DOAS) to derive column amounts of absorbers

F. Wittrock; H. Oetjen; A. Richter; S. Fietkau; T. Medeke; A. Rozanov; J. P. Burrows

2004-01-01

54

Mechanism for efficient generation of infrared radiation in a strongly preionized, externally maintained electrical discharge in inert gases  

Microsoft Academic Search

Inelastic-reaction-rate constants are calculated for argon at various degrees of preionization in order to determine the relative electrical-discharge powers pumping the upper levels, with allowance for energy cycling between ionized and metastable states. The lasing efficiency in the 1-2-micron wavelength range may be as high as 10 percent in strongly preionized, externally maintained electrical discharges in inert gases.

A. G. Molchanov; A. V. Platov

1983-01-01

55

Using Radiation Risk Models in Cancer Screening Simulations: Important Assumptions and Effects on Outcome Projections  

PubMed Central

Purpose: To evaluate the effect of incorporating radiation risk into microsimulation (first-order Monte Carlo) models for breast and lung cancer screening to illustrate effects of including radiation risk on patient outcome projections. Materials and Methods: All data used in this study were derived from publicly available or deidentified human subject data. Institutional review board approval was not required. The challenges of incorporating radiation risk into simulation models are illustrated with two cancer screening models (Breast Cancer Model and Lung Cancer Policy Model) adapted to include radiation exposure effects from mammography and chest computed tomography (CT), respectively. The primary outcome projected by the breast model was life expectancy (LE) for BRCA1 mutation carriers. Digital mammographic screening beginning at ages 25, 30, 35, and 40 years was evaluated in the context of screenings with false-positive results and radiation exposure effects. The primary outcome of the lung model was lung cancer–specific mortality reduction due to annual screening, comparing two diagnostic CT protocols for lung nodule evaluation. The Metropolis-Hastings algorithm was used to estimate the mean values of the results with 95% uncertainty intervals (UIs). Results: Without radiation exposure effects, the breast model indicated that annual digital mammography starting at age 25 years maximized LE (72.03 years; 95% UI: 72.01 years, 72.05 years) and had the highest number of screenings with false-positive results (2.0 per woman). When radiation effects were included, annual digital mammography beginning at age 30 years maximized LE (71.90 years; 95% UI: 71.87 years, 71.94 years) with a lower number of screenings with false-positive results (1.4 per woman). For annual chest CT screening of 50-year-old females with no follow-up for nodules smaller than 4 mm in diameter, the lung model predicted lung cancer–specific mortality reduction of 21.50% (95% UI: 20.90%, 22.10%) without radiation risk and 17.75% (95% UI: 16.97%, 18.41%) with radiation risk. Conclusion: Because including radiation exposure risk can influence long-term projections from simulation models, it is important to include these risks when conducting modeling-based assessments of diagnostic imaging. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11110352/-/DC1

Lee, Janie M.; McMahon, Pamela M.; Lowry, Kathryn P.; Omer, Zehra B.; Eisenberg, Jonathan D.; Pandharipande, Pari V.; Gazelle, G. Scott

2012-01-01

56

Melanocortin 1 receptor genotype: an important determinant of the damage response of melanocytes to ultraviolet radiation  

PubMed Central

The melanocortin 1 receptor gene is a main determinant of human pigmentation, and a melanoma susceptibility gene, because its variants that are strongly associated with red hair color increase melanoma risk. To test experimentally the association between melanocortin 1 receptor genotype and melanoma susceptibility, we compared the responses of primary human melanocyte cultures naturally expressing different melanocortin 1 receptor variants to ?-melanocortin and ultraviolet radiation. We found that expression of 2 red hair variants abolished the response to ?-melanocortin and its photoprotective effects, evidenced by lack of functional coupling of the receptor, and absence of reduction in ultraviolet radiation-induced hydrogen peroxide generation or enhancement of repair of DNA photoproducts, respectively. These variants had different heterozygous effects on receptor function. Microarray data confirmed the observed differences in responses of melanocytes with functional vs. nonfunctional receptor to ?-melanocortin and ultraviolet radiation, and identified DNA repair and antioxidant genes that are modulated by ?-melanocortin. Our findings highlight the molecular mechanisms by which the melanocortin 1 receptor genotype controls genomic stability of and the mutagenic effect of ultraviolet radiation on human melanocytes.—Kadekaro, A. L., Leachman, S., Kavanagh, R. J., Swope, V., Cassidy, P., Supp, D., Sartor, M., Schwemberger, S., Babcock, G., Wakamatsu, K., Ito, S., Koshoffer, A., Boissy, R. E., Manga, P., Sturm, R. A., Abdel-Malek, Z. A. Melanocortin 1 receptor genotype: an important determinant of the damage response of melanocytes to ultraviolet radiation.

Kadekaro, Ana Luisa; Leachman, Sancy; Kavanagh, Renny J.; Swope, Viki; Cassidy, Pamela; Supp, Dorothy; Sartor, Maureen; Schwemberger, Sandy; Babcock, George; Wakamatsu, Kazumasa; Ito, Shosuke; Koshoffer, Amy; Boissy, Raymond E.; Manga, Prashiela; Sturm, Richard A.; Abdel-Malek, Zalfa A.

2010-01-01

57

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

NASA Astrophysics Data System (ADS)

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

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

2005-07-01

58

Effect of leading radiation on the stability of intense shock waves in gases with an arbitrary equation of state  

NASA Astrophysics Data System (ADS)

The paper presents a linear-approximation study of the destabilizing effect of leading radiation on an intense shock wave in an ideal gas with an arbitrary equation of state. It is shown, in particular, that neutrally stable shock waves become unstable under the effect of the radiation. Conditions are established under which the appearance of the instability has a threshold character with respect to the radiation intensity. It is shown that the radiation can have a destabilizing effect on stable shock waves as well, including those in a perfect gas.

Egorushkin, S. A.; Uspenskii, V. S.

1990-06-01

59

Greenhouse Gases  

MedlinePLUS

... support life as we know it. Without the greenhouse effect, the average temperature of the Earth would be ... regulated independently of its warming effects. More about greenhouse gases’ effect on the climate » Also on Energy Explained Energy ...

60

Technical Note: Is radiation important for the high amplitude variability of the MOC in the North Atlantic?  

Microsoft Academic Search

Radiation is of fundamental importance to climate modeling and it is customary to assume that it is also important for the variability of North Atlantic Deep Water (NADW) formation and the meridional overturning cell (MOC). Numerous articles follow this scenario and incorporate radiation into the calculation. Using relatively old heat-flux maps based on measurements taken in the nineteen sixties, Sandal

D. Nof; L. Yu

2007-01-01

61

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

Microsoft Academic Search

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

Keith P. Shine

1991-01-01

62

Control of greenhouse gases emission by radiation-induced formation of useful products. Utilization of CO2  

NASA Astrophysics Data System (ADS)

Carbon dioxide (CO2) 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

63

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

64

Volume x-ray radiation of fast electrons at high-voltage nanosecond breakdown of dense gases  

NASA Astrophysics Data System (ADS)

X-ray spectra of fast electrons injected into a gas subjected to an external electric field are simulated. For weak fields, the simulated spectra are in good agreement with the Kramers theory. For strong fields, the x-ray spectrum differs considerably from the well-known spectra of x-ray tubes with massive cathodes and the radiated energy is much higher. As the voltage applied to a given discharge gap grows, the number of emitted photons reaches a maximum, while the radiated energy tends to saturate instead of decreasing.

Tkachev, A. N.; Yakovlenko, S. I.

2006-11-01

65

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

66

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

SciTech Connect

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

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

2007-02-01

67

Toxic gases.  

PubMed Central

An overview of the widespread use of gases and some volatile solvents in modern society is given. The usual circumstances in which undue exposure may occur are described. The most prominent symptoms and general principles of diagnosis and treatment are given and are followed by more specific information on the commoner, more toxic materials. While acute poisonings constitute the greater part of the paper, some indication of chronic disorders arising from repeated or prolonged exposure is also given.

Matthews, G.

1989-01-01

68

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

PubMed

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

2013-05-29

69

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

70

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

71

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

72

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

73

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

74

Greenhouse Gases  

NSDL National Science Digital Library

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

Consortium, The C.

2011-12-13

75

Feshbach resonances in ultracold gases  

SciTech Connect

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

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

2010-04-15

76

High order harmonic generation in rare gases.  

National Technical Information Service (NTIS)

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 lase...

K. S. Budil

1994-01-01

77

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

PubMed

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

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

2013-08-22

78

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 ...

Salter, Ms.

2009-10-22

79

COMPRESSED MEDICAL GASES GUIDELINE  

Center for Biologics Evaluation and Research (CBER)

... COMPRESSED MEDICAL GASES GUIDELINE. (REVISED) FEBRUARY 1989. ... COMPRESSED MEDICAL GASES GUIDELINE. INTRODUCTION. ... More results from www.fda.gov/drugs/guidancecomplianceregulatoryinformation/guidances

80

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.

Karcher, Bernd; Burkhardt, Ulrike; Ponater, Michael; Fromming, Christine

2010-01-01

81

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

PubMed

Estimates of the global radiative forcing by line-shaped contrails differ mainly due to the large uncertainty in contrail optical depth. Most contrails are optically thin so that their radiative forcing is roughly proportional to their optical depth and increases with contrail coverage. In recent assessments, the best estimate of mean contrail radiative forcing was significantly reduced, because global climate model simulations pointed at lower optical depth values than earlier studies. We revise these estimates by comparing the probability distribution of contrail optical depth diagnosed with a climate model with the distribution derived from a microphysical, cloud-scale model constrained by satellite observations over the United States. By assuming that the optical depth distribution from the cloud model is more realistic than that from the climate model, and by taking the difference between the observed and simulated optical depth over the United States as globally representative, we quantify uncertainties in the climate model's diagnostic contrail parameterization. Revising the climate model results accordingly increases the global mean radiative forcing estimate for line-shaped contrails by a factor of 3.3, from 3.5 mW/m(2) to 11.6 mW/m(2) for the year 1992. Furthermore, the satellite observations and the cloud model point at higher global mean optical depth of detectable contrails than often assumed in radiative transfer (off-line) studies. Therefore, we correct estimates of contrail radiative forcing from off-line studies as well. We suggest that the global net radiative forcing of line-shaped persistent contrails is in the range 8-20 mW/m(2) for the air traffic in the year 2000. PMID:20974909

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

2010-10-25

82

Modeling of the Arctic Cloud and Radiation Processes Observed during SHEBA: Importance of Heterogeneous Ice Nucleation  

NASA Astrophysics Data System (ADS)

Observations taken during the Surface Heat Budget of the Arctic Ocean (SHEBA) field experiment have shown that cloud radiative forcing at surface strongly depends on the presence of liquid water in cold clouds. In this project, we evaluate three microphysics schemes of various complexities that are implemented into the limited-area version of the Global Environmental Multiscale (GEM) model. The SHEBA year is simulated. Results show that the model generally underestimates the cloud radiative forcing at surface whatever the microphysics scheme used. The model underestimates the cloud liquid water, which is the main contributor to the cloud longwave radiative forcing. New parameterizations for deposition and immersion ice nucleation have been developed based on recent laboratory experiments of ice nucleation on uncoated and sulphuric acid-coated dust (kaolinite) particles. The new parameterizations are based on the classical theory of heterogeneous ice nucleation. Results show that the sulphuric acid coated-dust parameterization reproduces quite well the cloud liquid water and its relationships with cloud longwave radiative forcing. As a result, the simulated cloud radiative forcing is improved when compared to the original versions of the microphysics schemes.

Girard, E.; Du, P.

2010-12-01

83

Radiatively Important Trace Species (RITS) 1990: Tropical Pacific Ozone Minimum Expedition Nutrient, Chlorophyll-A, and Primary Productivity Data NOAA Ship MALCOLM BALDRIDGE, 3 January-18 February, 1990.  

National Technical Information Service (NTIS)

The National Oceanic and Atmospheric Administration (NOAA) Radiatively Important Trace Species (RITS) program objective is to understand the influence of oceanic chemical processes on the radiation balance of the Earth. During the period of 3 January-18 F...

D. W. Frazel G. A. Berberian J. McElroy G. L. Hitchcock

1991-01-01

84

Melanocortin 1 receptor genotype: an important determinant of the damage response of melanocytes to ultraviolet radiation.  

PubMed

The melanocortin 1 receptor gene is a main determinant of human pigmentation, and a melanoma susceptibility gene, because its variants that are strongly associated with red hair color increase melanoma risk. To test experimentally the association between melanocortin 1 receptor genotype and melanoma susceptibility, we compared the responses of primary human melanocyte cultures naturally expressing different melanocortin 1 receptor variants to ?-melanocortin and ultraviolet radiation. We found that expression of 2 red hair variants abolished the response to ?-melanocortin and its photoprotective effects, evidenced by lack of functional coupling of the receptor, and absence of reduction in ultraviolet radiation-induced hydrogen peroxide generation or enhancement of repair of DNA photoproducts, respectively. These variants had different heterozygous effects on receptor function. Microarray data confirmed the observed differences in responses of melanocytes with functional vs. nonfunctional receptor to ?-melanocortin and ultraviolet radiation, and identified DNA repair and antioxidant genes that are modulated by ?-melanocortin. Our findings highlight the molecular mechanisms by which the melanocortin 1 receptor genotype controls genomic stability of and the mutagenic effect of ultraviolet radiation on human melanocytes. PMID:20519635

Kadekaro, Ana Luisa; Leachman, Sancy; Kavanagh, Renny J; Swope, Viki; Cassidy, Pamela; Supp, Dorothy; Sartor, Maureen; Schwemberger, Sandy; Babcock, George; Wakamatsu, Kazumasa; Ito, Shosuke; Koshoffer, Amy; Boissy, Raymond E; Manga, Prashiela; Sturm, Richard A; Abdel-Malek, Zalfa A

2010-06-02

85

Determination of important nuclear fragmentation processes for human space radiation protection  

NASA Astrophysics Data System (ADS)

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

Lin, Zi-Wei

2007-03-01

86

Determination of important nuclear fragmentation processes for human space radiation protection  

SciTech Connect

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

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

2007-03-15

87

Potential emissions of radiatively active gases from soil to atmosphere with special reference to methane: Development of a global database (WISE)  

NASA Astrophysics Data System (ADS)

The role of soil in controlling production and fluxes of biotic greenhouse gases is the focus of research in progress at the International Soil Reference and Information Centre (ISRIC). There are two main goals in this project on World Inventory of Soil Emission Potentials (WISE). The first is to assemble a global soil database in association with the Land and Water Division of the Food and Agricultural Organization (FAO), using a ½° × ½° grid of geographic soil data (1:5 M scale). This "area" data will be linked to a database of soil profile "attribute" data using a geographical information system. The foundations for this work have now been put in place and, providing the soil profile collection programme proceeds satisfactorily, it is anticipated that a preliminary database should begin to emerge by the end of 1993. When the soil database is complete, the second thrust will be to make an inventory of the world's poorly drained soils, providing the geographical framework for an improved estimate of methane production potentials. To do this, controlled long-term field experiments are required and modeling techniques must be developed and tested. ISRIC is cooperating with the International Rice Research Institute (IRRI) in the Philippines for these aspects of the work. An important corollary to the development of a global soil database is that many requests are being received for soil information relevant for studies of "global change." At present, much of this information does not exist in an adequate format, so ISRIC is proceeding as rapidly as possible to implement the WISE digital database in a format which is compatible and user-friendly, for ultimate distribution in the public domain.

Batjes, Niels H.; Bridges, E. M.

1994-08-01

88

Estimation Of The Relative Importance Of Free Radical Oxidation And Direct Ozonation\\/UV Radiation Rates Of Micropollutants In Water  

Microsoft Academic Search

The relative importance of free radical and direct ozonation\\/photolysis oxidation of micropollutants in water can be estimated from simple kinetics of aqueous ozonation reactions provided these reactions develop in the slow kinetic regime of absorption. Knowledge of kinetic expressions of free radical initiation reactions and direct ozone-micropollutant or UV radiation-micropollutant reactions (and corresponding parameters: reaction rate constants, quantum yields, etc.)

F. J. Beltrán

1999-01-01

89

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

NASA Astrophysics Data System (ADS)

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

Hill, Mark

2012-07-01

90

Different versions of the right answer: the importance of measurement uncertainty in radiation dosimetry.  

PubMed

The performance of radiation dosemeters that are issued by approved individual monitoring services generally meet international standards, with typical results within a few tens of per cent of the reference value. Experienced dosimetry practitioners will understand the uncertainties and treat monitoring results with due caution. However, where different technologies (for example, where passive and electronic dosemeters) are used side by side, apparent disagreements can arise. These apparent disagreements between different systems can be significant, and dosimetrists must be prepared to help in addressing the issues that result. PMID:20952420

Gilvin, Phil; McWhan, Andrew

2010-10-14

91

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

PubMed

This discussion is motivated by observations of prompt oxygen changes occurring prior to a significant number of cancer cells dying (permanently stopping their metabolic activity) from therapeutic agents like large doses of ionizing radiation. Such changes must be from changes in the vasculature that supplies the tissue or from the metabolic changes in the tissue itself. An adapted linear-quadratic treatment is used to estimate the cell survival variation magnitudes from repair and reoxygenation from a two-fraction treatment in which the second fraction would happen prior to significant cell death from the first fraction, in the large fraction limit. It is clear the effects of oxygen changes are likely to be the most significant factor for hypofractionation because of large radiation doses. It is a larger effect than repair. Optimal dose timing should be determined by the peak oxygen timing. A call is made to prioritize near real time measurements of oxygen dynamics in tumors undergoing hypofractionated treatments in order to make these treatments adaptable and patient-specific. PMID:24061351

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

2013-09-24

92

On the importance of prompt oxygen changes for hypofractionated radiation treatments  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

93

Importance of the deep ocean for estimating decadal changes in Earth's radiation balance  

NASA Astrophysics Data System (ADS)

We use control run data from three Met Office Hadley Centre climate models to investigate the relationship between: net top-of-atmosphere radiation balance (TOA), globally averaged sea surface temperature (SST); and globally averaged ocean heat content (OHC) on decadal timescales. All three models show substantial decadal variability in SST, which could easily mask the long-term warming associated with anthropogenic climate change over a decade. Regression analyses are used to estimate the uncertainty of TOA, given the trend in SST or OHC over the same period. We show that decadal trends in SST are only weakly indicative of changes in TOA. Trends in total OHC strongly constrain TOA, since the ocean is the primary heat store in the Earth System. Integrating OHC over increasing model levels, provides an increasingly good indication of TOA changes. To achieve a given accuracy in TOA estimated from OHC we find that there is a trade-off between measuring for longer or deeper. Our model results suggest that there is potential for substantial improvement in our ability to monitor Earth's radiation balance by more comprehensive observation of the global ocean.

Palmer, Matthew D.; McNeall, Douglas J.; Dunstone, Nick J.

2011-07-01

94

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

95

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

96

Hope and challenge: the importance of ultraviolet (UV) radiation for cutaneous vitamin D synthesis and skin cancer.  

PubMed

Abstract Solar ultraviolet (UV)-radiation is the most important environmental risk factor for the development of non-melanoma skin cancer (most importantly basal and squamous cell carcinomas), that represent the most common malignancies in Caucasian populations. To prevent these malignancies, public health campaigns were developed to improve the awareness of the general population of the role of UV-radiation. The requirements of vitamin D is mainly achieved by UV-B-induced cutaneous photosynthesis, and the vitamin D-mediated positive effects of UV-radiation were not always adequately considered in these campaigns; a strict "no sun policy" might lead to vitamin D-deficiency. This dilemma represents a serious problem in many populations, for an association of vitamin D-deficiency and multiple independent diseases has been convincingly demonstrated. It is crucial that guidelines for UV-exposure (e.g. in skin cancer prevention campaigns) consider these facts and give recommendations how to prevent vitamin D-deficiency. In this review, we analyze the present literature to help developing well-balanced guidelines on UV-protection that ensure an adequate vitamin D-status without increasing the risk to develop UV-induced skin cancer. PMID:22536771

Reichrath, Jörg; Reichrath, Sandra

2012-04-01

97

Preliminary Investigation of Radiation Level and Some Radionuclides in Imported Food and Food Products.  

National Technical Information Service (NTIS)

A preliminary study of gross beta activity and content of some long-lived radionuclides associated with fission products in various types of imported food and food-products was carried out. Food samples were purchased monthly during 1976-1977 from general...

F. Sinakhom S. Mongkolphantha

1980-01-01

98

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

99

Observation of greenhouse gases from ground-based telescope  

Microsoft Academic Search

Long-term observation of greenhouse gases is very important to understand temporal variations of greenhouse gases. This January, Japanese satellite, GOSAT (greenhouse gases observing satellite) was launched and its operational observation has started. For supporting satellite observations, validation data such as obtained by ground-based observations are very important. However, there is no observation site in South America. In this study, I

Y. Hayashi; R. Imasu; T. Miyata

2009-01-01

100

Solids, Liquids, and Gases  

NSDL National Science Digital Library

Objective: Students will be introduced to solids, liquids, and gases. Students will identify key characteristics of the three states of matter. Everything is made of matter. Matter is made of atoms. Matter makes up solids, liquids, and gases. What are some similarities and differences between solids, liquids, and gases? Follow the link below to find out. Characteristics of the States of Matter The previous website gave some general characteristics for solids, liquids, and gases. Now ...

Rohlfing, Mrs.

2010-10-22

101

TREATMENT OF RADIOACTIVE WASTE GASES  

Microsoft Academic Search

The disposal of radioactive waste gases from the plant-scale processes ; at the Hanford Atomic Products Operation presents a problem that is of ; coniderable importance in plant operation. Equipment developed for the efficicnt ; removal of the two prinipal contaminants: 1) gaseous radioactive iodine; and 2) ; an aerosol composed of other fission products is described. The program has

A. G. Blasewitz; W. C. Schmidt

1958-01-01

102

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

103

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

SciTech Connect

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

Manickavasagam, S.; Menguec, M.P.

1994-09-01

104

Separation of polar gases from nonpolar gases  

DOEpatents

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

Kulprathipanja, S.

1986-08-19

105

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

106

Analysis of Historical Radiatively Important Trace Gases (RITG) Emissions: Development of a Trace Gas Accounting System (T-GAS) for 14 Countries.  

National Technical Information Service (NTIS)

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 t...

S. Piccot T. Lynch R. Kaufmann C. Cleveland B. Moore

1991-01-01

107

Impact of greenhouse gases on the Earth's ozone layer  

NASA Astrophysics Data System (ADS)

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

Zadorozhny, Alexander

108

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

109

Pump-probe studies of autoionizing states of noble gases combining laser and synchrotron radiation—The nf? Rydberg states of neon  

NASA Astrophysics Data System (ADS)

A mode-locked tunable Ti:Sapphire oscillator has been synchronized with the time structure of a storage ring and used to study the photoionization of noble gases. In multi-bunch operation of the ring the setup permits the observation of the dynamics from a few nanoseconds down to the tens of picoseconds range. The characteristics of the setup are demonstrated by following the two-color ionization of helium (via the 1s3p 1Po state) and argon (via the 3p5 (2P3/2) 3d state). In the CW mode we have also examined the two-color ionization of neon via the 2p5 (2P1/2) 3d? state. In neon the nf? Rydberg series was followed up to n˜50, and the quantum defect was determined.

Moise, Angelica; Alagia, Michele; Banchi, Luca; Ferianis, Mario; Prince, Kevin C.; Richter, Robert

2008-04-01

110

Radiative Heat Transfer in the Combustion Chamber of a Diesel Engine  

Microsoft Academic Search

Radiation is considered to be an important mode of heat transfer in diesel engines. It is mainly caused by a presence of soot particles in combustion gases. Spatial distribution of radiative heat flux on walls of the combustion chamber can be an important factor of thermal load of some parts of the engine. The paper presents a numerical method used

P. Furmanski; J. Banaszek; T. S. Wisniewski

1999-01-01

111

Noble gases in meteorites  

Microsoft Academic Search

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

Donald D. Bogard

1971-01-01

112

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...

113

Optical remote sensing of greenhouse gases in the troposphere  

Microsoft Academic Search

A system of satellite borne sensor is proposed for measuring the column amount of green house gases in the troposphere from observations of near infrared solar radiation in the sun glint region reflected from water surface of ocean and lakes. A high accuracy determination of the column amount of gases is achieved by measuring the difference of absorption line of

Tadao Aoki; Masashi Fukabori; Teruo Aoki

2001-01-01

114

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

PubMed

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

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

2013-04-14

115

Gases in Seawater  

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

116

Greenhouse gases and the metallurgical process industry  

Microsoft Academic Search

The Kyoto Protocol of December 1997 highlighted the importance of greenhouse gas emissions. The metallurgical process industry\\u000a is a contributor to these emissions and would be seriously affected by measures curtailing them. The present lecture offers\\u000a a brief review of the greenhouse effect, the sources of greenhouse gases, the potential effect of these gases on global warming,\\u000a the response of

Claude H. P. Lupis; C. H. P

1999-01-01

117

Extended thermodynamics of dense gases  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

118

Ultracold gases: Atom SQUID  

NASA Astrophysics Data System (ADS)

Superfluid ultracold gases in designer potentials are analogous to superconducting electronic circuits. The study of these systems refines our understanding of flow and dissipation in quantum fluids, and has applications for inertial sensing and metrology.

Edwards, Mark

2013-02-01

119

Electrochemistry of Dissolved Gases.  

National Technical Information Service (NTIS)

The electrochemistry of various dissolved gases has been investigated as a function of the gas, solution pH, supporting electrolyte, electrode material, and the preconditioning of the electrode surfaces. These investigations have been conducted through th...

D. T. Sawyer

1965-01-01

120

Regulating Greenhouse Gases  

NSDL National Science Digital Library

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

Kqed; Domain, Teachers'

121

An alternative method to optimise the SLW Grey Gases  

NASA Astrophysics Data System (ADS)

The industrial combustion sector needs relatively simple but accurate radiation gas model to perform multiphysics simulations. Built with high resolution spectral absorption line databases, the Spectral-Line-Weighted-Sum of Grey-Gases model (SLWSGG) with a restricted number of grey gases, may meet this need. This paper presents an easier method to optimise the SLW grey gases in comparison with the original method. The optimisation procedure proposed in this work is based on total quantities values (radiative fluxes or source terms) analytically calculated on the equivalent 1D medium.

Evrard, P.; Feldheim, V.; Lybaert, P.

2012-11-01

122

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

PubMed

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

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

2013-04-11

123

Imbalanced Fermi gases at unitarity  

NASA Astrophysics Data System (ADS)

We consider imbalanced Fermi gases with strong attractive interactions, for which Cooper-pair formation plays an important role. The two-component mixtures consist either of identical fermionic atoms in two different hyperfine states, or of two different atomic species both occupying only a single hyperfine state. In both cases, the number of atoms for each component is allowed to be different, which leads to a spin imbalance, or spin polarization. Two different atomic species also lead to a mass imbalance. Imbalanced Fermi gases are relevant to condensed-matter physics, nuclear physics and astroparticle physics. They have been studied intensively in recent years, following their experimental realization in ultracold atomic Fermi gases. The experimental control in such a system allows for a systematic study of the equation of state and the phase diagram as a function of temperature, spin polarization and interaction strength. In this review, we discuss the progress in understanding strongly-interacting imbalanced Fermi gases, where the main goal is to describe the results of the highly controlled experiments. We start by discussing Feshbach resonances, after which we treat the imbalanced Fermi gas in mean-field theory to give an introduction to the relevant physics. We encounter several unusual superfluid phases, including phase-separation, gapless Sarma superfluidity, and supersolidity. To obtain a more quantitative description of the experiments, we review also more sophisticated techniques, such as diagrammatic methods and the renormalization-group theory. We end the review by discussing two theoretical approaches to treat the inhomogeneous imbalanced Fermi gas, namely the Landau-Ginzburg theory and the Bogoliubov-de Gennes approach.

Gubbels, K. B.; Stoof, H. T. C.

2013-04-01

124

Investigation of the evolution of modulated radiative blast waves created by high intensity laser - cluster interaction  

Microsoft Academic Search

Radiative blast waves exhibiting instabilities are common and play an important role in astrophysics. Certain aspects of these astrophysical waves can be reproduced in suitably designed laboratory experiments. Previous laboratory experiments have shown that blast waves can be created from intense laser-cluster interactions and the evolution of these waves in high Z cluster gases is radiative, with trajectories that deviate

H. J. Quevedo; I. T. Kim; W. Bang; D. R. Symes; J. Osterhoff; R. Faustlin; M. Maurer; A. C. Bernstein; A. S. Moore; E. T. Gumbrell; A. D. Edens; R. A. Smith; T. Ditmire

2008-01-01

125

Verification of imported food upon import for radiation processing: Dried herbs, including herbs used in food supplements, and spices by PSL and TL  

NASA Astrophysics Data System (ADS)

The Italian National Institute of Health in 2005-2006 performed an analytical survey of import on dried spices and herbs, including herbs used in food supplements, to investigate the entry in Italy of irradiated, and not correctly labelled, raw materials. In this survey, 52 samples, including nine herbal extracts, were collected. The method of photo-stimulated luminescence (PSL) was applied to all samples and only samples screened positive or intermediate with PSL were analysed by using the thermo-luminescence (TL) method. Out of the 12 samples screened positive or intermediate with PSL, the TL method confirmed irradiation of five samples (10% of the total assayed samples). One out of these five samples was a herbal supplement whereas three were herbal extracts that are known to be used as ingredients of herbal supplements, and another one was a spice.

Boniglia, C.; Aureli, P.; Bortolin, E.; Onori, S.

2009-07-01

126

Solids, Liquids, and Gases  

NSDL National Science Digital Library

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

Sibley, Ms.

2009-10-22

127

High Order Harmonic Generation in Rare Gases  

Microsoft Academic Search

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 rm(I ~ 10^{13} - 10^ {14} W\\/cm^2) is focused into a dense rm({~}10^ {17} particles\\/cm^3) atomic medium, causing the atoms

Kimberly Susan Budil

1994-01-01

128

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

129

BAGI: a new concept for detecting and tracking hazardous gases  

Microsoft Academic Search

A new concept for the detection and tracking of toxic or flammable gases resulting from accidental spills or leaks is presented. The Backscatter Absorption Gas Imaging (BAGI) technique is based on the optical radiation augmentation of the field of view of an imaging device by laser radiation corresponding to an absorption line of the gas species to be detected. The

McRae

1983-01-01

130

Solids, Liquids, and Gases  

NSDL National Science Digital Library

What do you know about the 3 states of matter? Good Morning 2nd graders! Today we will be learning about the different states of matter : solids, liquids, and gases . Have fun working with your partner and follow directions carefully! First, make sure you get a 3 column graphic organizer and fill ...

Swaim, Mrs.

2012-12-01

131

Strongly interacting Fermi gases  

NASA Astrophysics Data System (ADS)

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 measurements on the thermodynamics of a strongly interacting Fermi gas across the superfluid transition. The onset of superfluidity is directly observed in the compressibility, the chemical potential, the entropy, and the heat capacity. Our measurements provide benchmarks for current many-body theories on strongly interacting fermions. Secondly, we have studied the evolution of fermion pairing from three to two dimensions in these gases, relating to the physics of layered superconductors. In the presence of p-wave interactions, Fermi gases are predicted to display toplogical superfluidity carrying Majorana edge states. Two possible avenues in this direction are discussed, our creation and direct observation of spin-orbit coupling in Fermi gases and the creation of fermionic molecules of 23Na 40K that will feature strong dipolar interactions in their absolute ground state.

Bakr, W.; Cheuk, L. W.; Ku, M. J.-H.; Park, J. W.; Sommer, A. T.; Will, S.; Wu, C.-H.; Yefsah, T.; Zwierlein, M. W.

2013-08-01

132

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

133

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

NASA Astrophysics Data System (ADS)

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

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

1990-06-01

134

Volcanic Gases and Their Effects  

MedlinePLUS

... Please see the web article, " Volcanic Gases and Climate Change Overview " for additional information. Hydrogen sulfide (H 2 S) ... Please see the web article, " Volcanic Gases and Climate Change Overview " for more information on Volcanic versus anthropogenic ...

135

Investigation of Ultrafast Laser-Driven Radiative Blast Waves  

Microsoft Academic Search

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

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

2001-01-01

136

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,...

137

Absorptance of infrared radiation by methane at elevated temperatures  

Microsoft Academic Search

In large-scale fires and flames, radiative transport can be an important factor determining the rate of fuel volatilization and flame spread in condensed fuels, and in general can affect the amount of soot that is produced by the flame. The radiant flux can be significantly attenuated by core hydrocarbon gases that have absorption features in the infrared. The spectral absorptance

S. P. Fuss; O. A. Ezekoye; M. J. Hall

1996-01-01

138

DOSIMETRY MODELING OF INHALED TOXIC REACTIVE GASES  

EPA Science Inventory

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

139

Studying the Important Relationship Between Earth's Plasma Sheet and the Outer Radiation Belt Electrons Using Newly Calibrated and Corrected Themis-Sst Data  

NASA Astrophysics Data System (ADS)

Most recently, the solid-state telescope (SST) data from the THEMIS mission, which consisted of 5 spacecraft in highly elliptic, equatorial orbits that have traversed the outer radiation belt and sampled the plasma sheet for more than 4 years, have been characterized, calibrated, and decontaminated. Here, we present a brief introduction on this corrected dataset and go into detail on the valuable resource it provides to address science questions concerning the important relationship between ~1 keV-10's keV electrons in the plasma sheet and 100's keV-MeV electrons in Earth's outer radiation belt. We demonstrate this by presenting preliminary results on: studying phase space density (PSD) radial gradients for fixed first and second adiabatic invariants from the radiation belt into the plasma sheet, examining pitch angle distributions near the boundary between these two regions, and studying the boundary region itself around the last closed drift shell and the role of magnetopause shadowing losses. We examine the dependence of PSD radial gradients on the first and second invariants to test previous results [e.g., Turner et al., GRL, 2008; Kim et al., JGR, 2010] that reveal mostly positive radial gradients for lower energy electrons (10's - couple hundred keV) but negative gradients for relativistic electrons beyond geosynchronous orbit. This directly relates to the current theory that lower energy electrons have a source in the plasma sheet and are introduced to the ring current and radiation belt via substorm injections and enhanced convection, and these particles then generate the waves necessary to accelerate a fraction of this seed population to relativistic energies, providing a source of the outer radiation belt. Next, we take advantage of the pitch angle resolved differential energy fluxes to examine variations in pitch angle distributions to establish the role that Shabansky drift orbits, which break electrons' second adiabatic invariant, play on outer belt electron dynamics. Finally, THEMIS spacecraft often sample the last closed drift shell and the dayside magnetopause, and we use this new dataset to investigate dynamics in this important region as well as losses to the outer boundary, which may be critical to outer radiation belt dropout events. These preliminary examples are just a small sampling of the variety of studies that can be conducted with the THEMIS-SST dataset. We conclude with a brief discussion of how this corrected dataset should prove invaluable for sampling the source population in the plasma sheet and the outer radiation belt beyond geosynchronous orbit during the upcoming NASA Radiation Belt Storm Probes mission.

Cruce, P. R.; Turner, D. L.; Angelopoulos, V.; Larson, D. E.; Shprits, Y.; Huang, C.; Ukhorskiy, A. Y.

2011-12-01

140

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

PubMed Central

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

Krojer, Tobias; von Delft, Frank

2011-01-01

141

Implementation of the weighted sum of gray gases model to a narrow band: Application and validity  

SciTech Connect

Modeling the nongray behavior of combustion gases, such as water vapor and carbon dioxide, is very important for calculating the radiative heat transfer in furnaces and boilers. Here, the weighted sum of gray gases model (WSGGM) is applied to narrow bands of water vapor for analyzing radiative heat transfer in nongray media. For a given narrow band, the band mean spectral emissivity is represented by a weighted sum of gray gas emissivities expressed in terms of absorption coefficients, weighting factors, absorbing gas density, and path length. Five types of temperature-versus-narrow band absorption coefficient relation are suggested, and comparisons between the modeled emissivity and that of the original narrow band model are made and shown at a few typical bands. Total and low-resolution spectral intensities at the boundary are obtained for uniform, parabolic, boundary-layer-type temperature and parabolic concentration profiles using the WSGGM with five gray gases. Results using the Curtis-Godson approximation are compared with the WSGGM computations for each narrow band. The results using the WSGGM show good agreement with the Curtis-Godson approximation results, and especially, two of the WSGGMs with wave number-dependent absorption coefficient show highly accurate results with a few percent error in the total wall heat flux. The WSGGMs with wave number-independent absorption coefficients are, however, more useful for total spectrum computation, with a slight sacrifice in the accuracy.

Kim, O.J.; Song, T.H. [Korea Advanced Inst. of Science and Technology, Kusong, Taejon (Korea, Republic of). Dept. of Mechanical Engineering

1996-12-01

142

Effects of solar electromagnetic radiation on the terrestrial environment.  

NASA Astrophysics Data System (ADS)

Contents: Atmospheric structure and composition (thermosphere, stratosphere and mesosphere structure and chemistry, tropospheric chemistry). The climate system (current questions, introduction to simple climate models, trapping of thermal radiation by atmospheric constituents, thermal feedback by clouds and water vapor, anthropogenic modulation of trace gases important for climate, atmospheric and oceanic circulation and the seasons, primitive climate, the carbon cycle and the faint-early-Sun). Solar radiation drives the biosphere (origins of photosynthesis, photosynthesis in action, harvesting the sunlight, net primary productivity).

Dickinson, R. E.

143

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

144

Greenhouse Gases Observation from the GOSAT Satellite  

NASA Astrophysics Data System (ADS)

The Greenhouse gases Observing Satellite (GOSAT) is a satellite to monitor the carbon dioxide (CO2) and the methane (CH4) globally from orbit. The two instruments are accommodated on GOSAT. The Greenhouse gases Observing Sensor is a Fourier-Transform Spectrometer (FTS), which detects gas absorption spectra of the solar short wave infrared (SWIR) reflected on the earth_fs surface as well as of the thermal infrared (TIR) radiated from the ground and the atmosphere. The FTS is capable of detecting three narrow bands (0.76, 1.6, and 2 micron) and a wide band (5.5-14.3 micron) with 0.2 cm-1 spectral resolution. The cloud and aerosol sensor is an imager of ultraviolet (UV), visible, and SWIR to correct cloud and aerosol interference. The presentation includes the instrument design, pre-launch calibration and onboard calibration schemes; as well as, some test results using the Bread Board Model (BBM).

Kuze, A.; Kondo, K.; Kaneko, Y.; Hamazaki, T.

2005-12-01

145

Ultrapure gases for GERDA  

NASA Astrophysics Data System (ADS)

The GERDA experiment searches for the neutrinoless double beta decay of 76Ge. A major reduction of background is envisaged by operating almost bare germanium diodes in ultrapure liquid nitrogen or liquid argon. The purity of the cryogenic liquid in terms of 222Rn is crucial for the success of the experiment. In this work techniques for measuring 222Rn in nitrogen and argon at the ?Bq/m3 level are presented. It is shown that the required purity can be obtained for both gases, nitrogen and argon.

Simgen, H.

2006-07-01

146

Radiation dosimetry  

Microsoft Academic Search

This article summarized 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

1991-01-01

147

Characterization of air-sea gas exchange processes and dissolved gas/ice interactions using noble gases  

NASA Astrophysics Data System (ADS)

In order to constrain the processes controlling the cycles of biogeochemically important gases such as O2 and CO2, and thereby infer rates of biological activity in the upper ocean or the uptake of radiatively important ``greenhouse'' gases, the noble gases are used to characterize and quantify the physical processes affecting the dissolved gases in aquatic environments. The processes of vertical mixing, gas exchange, air injection, and radiative heating are investigated using a 2 year time-series of the noble gases, temperature, and meteorological data from Station S near Bermuda, coupled with a 1-dimensional upper ocean mixing model to simulate the physical processes in the upper ocean. The rate of vertical mixing that best simulates the thermal cycle is 1.1 +/- 0.1 × 10-4 m s-1. The gas exchange rate required to simulate the data is consistent with the formulation of Wanninkhof (1992) to +/-40%, while the formulation of Liss and Merlivat (1986) must be increased by a factor of 1.7 +/- 0.6. The air injection rate is consistent with the formulation of Monahan and Torgersen (1991) using an air entrainment velocity of 3 +/- 1 cm s-1. Gas flux from bubbles is dominated on yearly time-scales by larger bubbles that do not dissolve completely, while the bubble flux is dominated by complete dissolution of bubbles in the winter at Bermuda. In order to obtain a high-frequency time-series of the noble gases to better parameterize the gas flux from bubbles, a moorable, sequential noble gas sampler was developed. Preliminary results indicate that the sampler is capable of obtaining the necessary data. Dissolved gas concentrations can be significantly modified by ice formation and melting, and due to the solubility of He and Ne in ice, the noble gases are shown to be unique tracers of these interactions. A three-phase equilibrium partitioning model was constructed to quantify these interactions in perennially ice-covered Lake Fryxell, and this work was extended to oceanic environments. Preliminary surveys indicate that the noble gases may provide useful and unique information about interactions between water and ice. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

Hood, Eda Maria

148

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

149

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

150

Non-C02 greenhouse gases; all gases count  

Microsoft Academic Search

Under the Kyoto Protocol, a group of countries commit themselves to reduce the emissions of greenhouse gases to some 5% below the 1990 level. Countries can decide to spread their reduction commitment over several gases to lower compliance costs. Employing a multi-gas strategy can offer considerable efficiency gains because of the widely diverging marginal abatement cost for the different emission

Willemien Kets; Gerard Verweij

2005-01-01

151

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

152

Diffusivity of Lattice Gases  

NASA Astrophysics Data System (ADS)

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

Quastel, Jeremy; Valkó, Benedek

2013-10-01

153

Voluntary Reporting of Greenhouse Gases  

EIA Publications

The Voluntary Reporting of Greenhouse Gases Program established a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., can report to the EIA, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

Information Center

2011-02-01

154

The physics of ionized gases  

SciTech Connect

This volume reports the proceedings of the symposium on physics of ionized gases. The program emphasized physical processes associated with the physics of ionized gases: atomic collision processes, particle and laser beam interaction with solids, low temperature plasmas and general plasma theory.

Tanovic, L.; Konjevic, N.; Tanovic, N.

1989-01-01

155

Isothermal compressors for process gases  

Microsoft Academic Search

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

E. Wiederuh; D. Meinhart

1992-01-01

156

Laboratory and field tunable diode laser measurements of trace atmospheric species and processes of importance to the stratospheric aerosol sulfate layer  

Microsoft Academic Search

The stratospheric aerosol sulfate layer (Junge layer) may influence the earth's radiation budget, climate, and stratospheric ozone levels. In this paper, we present research activities at the National Center for Atmospheric Research employing high resolution tunable diode laser absorption spectroscopy which address two separate aspects of the Junge layer: laboratory heterogeneous measurements of reaction probabilities between stratospheric gases of importance

Alan Fried; Bruce E. Henry; Scott D. Sewell; Jack G. Calvert; James R. Drummond; Michael Mozurkewich

1994-01-01

157

BAGI: A New Concept for Detecting and Tracking Hazardous Gases.  

National Technical Information Service (NTIS)

A new concept for the detection and tracking of toxic or flammable gases resulting from accidental spills or leaks is presented. The Backscatter Absorption Gas Imaging (BAGI) technique is based on the optical radiation augmentation of the field of view of...

T. G. McRae

1983-01-01

158

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

Microsoft Academic Search

Through three-dimensional global model studies on atmospheric composition and transport, we are improving our quantitative understanding of the origins and behavior of trace gases that affect Earth's radiative energy balance and climate. We will focus, in this paper, on the simulations of three individual trace gases including CFC-11, methyl chloroform, and methane. We first used our chemical tracer model to

C. Y. J. Kao; E. Morz; X. Tie

1991-01-01

159

Classical harmonic generation in rare gases  

SciTech Connect

The classical microcanonical ensemble approach to high-harmonic generation (HHG) in rare gases subjected to intense laser fields is studied. We show that the ensemble spectrum is a ''sampled'' version of the single trajectory spectrum. Unlike the radiation of the single ensemble member, the total ensemble radiation possesses all the basic HHG features: odd laser harmonics, plateau, and cutoff. The sampling theorem for uniform grids is used to explain why the ensemble spectrum can be computed accurately with a very small number of ensemble members compared to the Monte Carlo method. Furthermore, The phase space relevant to harmonic generation is found to be significantly smaller than the field free microcanonical ensemble. In addition we demonstrate the seeding effect that was predicted and observed in quantum simulation. For circular polarization, we verify that the harmonic generation is highly suppressed even when the argument of the three-step model does not apply. All the findings are numerically calculated for the xenon atom.

Uzdin, Raam; Moiseyev, Nimrod [Department of Physics, Technion, Israel Institute of Technology (Israel)

2010-06-15

160

Monitoring greenhouse gases with astronomical observations  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

161

Monitoring greenhouse gases with astronomical observations  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

162

Air Pollution Export from and Import to North America: Experimental Evidence  

Microsoft Academic Search

North America (Canada and the USA) contains only 5% of the world’s population but accounts for 15–23% of the world’s emissions in terms of trace gases important for the radiative processes of the atmosphere, ozone formation and acid rain. As a result, North America has a strong impact on global atmospheric chemistry. The bulk of North American trace gas and

Owen R. Cooper; David D. Parrish

163

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

164

Environmental Implications of Anesthetic Gases  

PubMed Central

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.

Yasny, Jeffrey S.; White, Jennifer

2012-01-01

165

IMG, interferometric measurement of greenhouse gases from space  

NASA Astrophysics Data System (ADS)

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

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

1994-01-01

166

Different Fuels and Greenhouse gases  

NSDL National Science Digital Library

In this video, Peter Hall (a senior scientist in the field of bioenergy research at Crown Research Institute Scion) describes how different products (e.g. coal, wood) produce differing amounts of greenhouse gases.

Waikato, The U.; Hub, Science L.

167

Defining Local-Regional Control and Its Importance in Locally Advanced Non-small Cell Lung Carcinoma: A Radiation Therapy Oncology Group Analysis.  

PubMed

INTRODUCTION: Local-regional control (LRC) rates for non-small cell lung cancer after chemoradiotherapy were studied (using two different definitions of LRC) for the association between LRC and survival. METHODS: Seven legacy Radiation Therapy Oncology Group trials of chemoradiotherapy for locally advanced non-small cell lung cancer were analyzed. Two different definitions of LRC were studied: (1) freedom from local progression (FFLP-LRC), the traditional Radiation Therapy Oncology Group methodology, in which a failure is intrathoracic tumor progression by World Health Organization criteria; and (2) response-mandatory (strict-LRC), in which any patient not achieving at least partial response was considered to have failure at day 0. Testing for associations between LRC and survival was performed using a Cox multivariate model that included other potential predictive factors. RESULTS: A total of 1390 patients were analyzed. The LRC rate at 3 years was 38% based on the FFLP-LRC definition and 14% based on the strict-LRC definition. Performance status, concurrent chemotherapy, and radiotherapy dose intensity (biologically equivalent dose) were associated with better LRC (using either definition). With the strict-LRC definition (but not FFLP-LRC), age was also important. There was a powerful association between LRC and overall survival (p < 0.0001) on univariate and multivariate analyses. Age, performance status, chemotherapy sequencing, and biologically equivalent dose were also significantly associated with survival. Histology and gender were also significant if the strict-LRC model was used. CONCLUSIONS: LRC is associated with survival. The definition of LRC affects the results of these analyses. A consensus definition of LRC, incorporating functional imaging and/or central review, is needed, with the possibility of using LRC as a surrogate end point in future trials. PMID:22237265

Machtay, Mitchell; Paulus, Rebecca; Moughan, Jennifer; Komaki, Ritsuko; Bradley, Jeffrey; Choy, Hak; Albain, Kathy; Movsas, Benjamin; Sause, William T; Curran, Walter J

2012-01-31

168

Modeling of Global Biogenic Emissions for Key Indirect Greenhouse Gases (Invited)  

NASA Astrophysics Data System (ADS)

One key element of assessing the impact of human activities on climate change is to accurately estimate the emissions of not only direct but also indirect (reactive) greenhouse gases (GHGs). Direct GHGs, e.g. carbon dioxide (CO2), methane (CH4), and ozone (O3), can warm up the Earths surface by absorbing the terrestrial infrared (IR) radiation. Reactive gases, e.g. carbon monoxide (CO), nitric oxides (NOx), and non-methane volatile organic compounds (NMVOCs), though transparent to IR radiation, can impact the climate system by altering CH4 and tropospheric O3 concentrations, two important GHGs, through complex chemical processes. In this study, we integrated a biogenic model within a terrestrial ecosystem model to investigate the vegetation and soil emissions of key indirect GHGs, e.g., isoprene, monoterpene, other NMVOCs (OVOC), CO, and NOx. The combination of a high-resolution terrestrial ecosystem model with satellite data allows investigation of the potential changes in biogenic emissions of indirect GHGs due to atmospheric CO2 increases, and changes in climate and land-use practices.

Jain, A.; Yang, X.

2009-12-01

169

Laser driven X-ray parametric amplification in neutral gases—a new brilliant light source in the XUV  

NASA Astrophysics Data System (ADS)

In this paper we present the experimental setup and results showing a new type of strong-field parametric amplification of high-order harmonic radiation. With a simple semi-classical model, we can identify the most important experimental parameters, the spectral range and the small signal gain in gases. Using a single stage amplifier, a small signal gain of 8000 has been obtained in argon for the spectral range of 40-50 eV, using 350 fs, 7 mJ pulses at 1.05 ?m. An outlook for an experiment employing a double stage gas system will be given.

Aurand, B.; Seres, J.; Bagnoud, V.; Ecker, B.; Hochhaus, D. C.; Neumayer, P.; Seres, E.; Spielmann, C.; Zielbauer, B.; Zimmer, D.; Kuehl, T.

2011-10-01

170

Rare gases in Samoan xenoliths  

NASA Astrophysics Data System (ADS)

The rare gas isotopic compositions of residual harzburgite xenoliths from Savai'i (SAV locality) and an unnamed seamount south of the Samoan chain (PPT locality) provide important constraints on the rare gas evolution of the mantle and atmosphere. Despite heterogeneous trace element compositions, the rare gas characteristics of the xenoliths from each of the two localities are strikingly similar. SAV and PPT xenoliths have 3He/4He ratios of 11.1 +/- 0.5 RA and 21.6 +/- 1 RA, respectively; this range is comparable to the 3He/4He ratios in Samoan lavas and clearly demonstrates that they have trapped gases from a relatively undegassed reservoir. The neon results are not consistent with mixing between MORB and a plume source with an atmospheric signature. Rather, the neon isotopes reflect either a variably degassed mantle (with a relative order of degassing of Loihi < PPT < Reunion < SAV < MORB), or mixing between the Loihi source and MORB. The data supports the conclusions of Honda et al. that the 20Ne/22Ne ratio in the mantle more closely resembles the solar ratio than the atmospheric one. 40Ar/36Ar ratios in the least contaminated samples range from 4,000 to 12,000 with the highest values in the 22 RA PPT xenoliths. There is no evidence for atmospheric 40Ar/36Ar ratios in the mantle source of these samples, which indicates that the lower mantle may have 40Ar/36Ar ratios in excess of 5,000. Xenon isotopic anomalies in 129Xe and 136Xe are as high as 6%, or about half of the maximum MORB excess and are consistent with the less degassed nature of the Samoan mantle source. These results contradict previous suggestions that the high 3He/4He mantle has a near-atmospheric heavy rare gas isotopic composition. Present address: Lamont-Doherty Geological Observatory, Palisades, NY 10964, USA.

Poreda, R. J.; Farley, K. A.

1992-09-01

171

Importance of Dissolved Organic Carbon Optical Properties, Iron, and Ultraviolet Radiation for the Production of Dissolved Gaseous Mercury in Freshwater Systems  

NASA Astrophysics Data System (ADS)

The emission of dissolved gaseous mercury (DGM) from water surfaces into the atmosphere is an important process because it removes mercury from aquatic systems, where it might otherwise be available for methylation and bioaccumulation. One of the most important factors that contributes to the production and emission of DGM from aquatic systems is interaction with ultraviolet radiation (UVR). Irradiation of aqueous mercury by UVR can directly cause both photooxidation, which may reduce mercury emissions from water surfaces, and photoreduction, which may increase emission. Numerous studies have demonstrated that dissolved organic carbon (DOC) also plays an important role in the cycling of mercury through both binding and photoreactions. The strength of the Hg-DOC interaction is dependent, in part, on DOC characteristics, which can be evaluated using optical techniques such as absorbance and fluorescence. These two optical properties of DOC vary as a function of DOC source or the degree of oxidation and can therefore be used as a proxy for chemical characteristics (aromatic content, etc.). Additionally, iron plays a role in the photoreactivity of DOC and absorption of UVR in freshwater systems, and may therefore be important in DGM production. This study assesses the effects of UVR, DOC optical characteristics, and iron on the formation of DGM using controlled laboratory experiments in a 2 x 2 x 2 matrix. A DOC solution (8 mg C/L) and deionized water were each spiked with mercury to achieve a minimum concentration of 50 ng/L and allowed to equilibrate in the dark for 24 hours. Iron was added to half the sample vials (10 uMol/L), and samples were incubated in both light (UVR) and dark conditions for 6 hours at room temperature (25 C). DGM and total dissolved mercury were measured at the beginning and end of the exposures using double-focusing gold trap amalgamation and atomic fluorescence spectroscopy, and concentrations were compared between treatments. The initial DOC solution was then photooxidized using UVR to alter its optical properties (fluorescence ratio, spectral slope, SUVA), and the experiment was repeated to asses the effect of DOC chemical characteristics on DGM production. Initial results are promising and suggest that both iron and DOC influence the amount of DGM formed in solution. Further replication and data analysis are required to completely understand the results of this experiment. The results of this experiment will help elucidate controls on DGM production in freshwater systems, and may identify DOC optical properties that would be useful to monitor in conjunction with field mercury emission measurements in aquatic environments.

Wollenberg, J. L.; Peters, S. C.

2006-12-01

172

Radiation Laws  

NSDL National Science Digital Library

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

Astronomy, Department O.; Knoxville, University O.

173

Spin Transport in Bose Gases  

NASA Astrophysics Data System (ADS)

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

van Driel, H. J.

2012-12-01

174

Characterizing the uncertainty of pyrogenic emissions of trace gases inferred from space-borne data due to injection heights and aerosol optical properties.  

NASA Astrophysics Data System (ADS)

Fires are amongst the most important global contributors of climate-relevant gases and particles, with far-reaching implications for the atmospheric radiation budget, surface air quality, and the water cycle. However, our current understanding of the magnitude and uncertainty of these pyrogenic emissions is far from complete. Formaldehyde (HCHO) is directly emitted by fires and produced chemically by the oxidation of co-emitted volatile organic compounds. We use the GEOS-Chem CTM to relate the observed variability of HCHO columns from the ESA SCIAMACHY satellite instrument to surface emissions of precursor trace gases from tropical and boreal fires. An important focus of the presentation will be quantifying the uncertainty of these inferred emissions due to uncertainties associated with pyroconvection, oxidant chemistry, and assumed aerosol optical properties. We will assess the impact of these uncertainties on calculations of tropospheric ozone.

Gonzi, Siegfried; Palmer, Paul I.; Barkley, Mike P.

2010-05-01

175

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

176

On flame kernel formation and propagation in premixed gases  

SciTech Connect

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

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

2010-12-15

177

Removal of acid gases in dry scrubbing of hot gases  

Microsoft Academic Search

This patent describes a method for the removal of sulfur oxide gases from a flue gas containing the same. The method comprising: dispersing finely-divided dry hydrated lime in a humid inert gas having a relative water vapor pressure higher than the fugacity of at least a monomolecular layer of water thereby adsorbed on the hydrated lime; bringing the dispersed hydrated

1989-01-01

178

An alternative approach to establishing trade-offs among greenhouse gases.  

PubMed

The Kyoto Protocol permits countries to meet part of their emission reduction obligations by cutting back on gases other than CO2 (ref. 1). This approach requires a definition of trade-offs among the radiatively active gases. The Intergovernmental Panel on Climate Change has suggested global warming potentials for this purpose, which use the accumulated radiative forcing of each gas by a set time horizon to establish emission equivalence. But it has been suggested that this approach has serious shortcomings: damages or abatement costs are not considered and the choice of time horizon for calculating cumulative radiative force is critical, but arbitrary. Here we describe an alternative framework for determining emission equivalence between radiatively active gases that addresses these weaknesses. We focus on limiting temperature change and rate of temperature change, but our framework is also applicable to other objectives. For a proposed ceiling, we calculate how much one should be willing to pay for emitting an additional unit of each gas. The relative prices then determine the trade-off between gases at each point in time, taking into account economical as well as physical considerations. Our analysis shows that the relative prices are sensitive to the lifetime of the gases, the choice of target and the proximity of the target, making short-lived gases more expensive to emit as we approach the prescribed ceiling. PMID:11287950

Manne, A S; Richels, R G

2001-04-01

179

Impact of greenhouse gases on the Earth's ozone layer  

Microsoft Academic Search

A numerical 2-D zonally averaged interactive dynamical radiative-photochemical model of the ozonosphere including aerosol physics is used to examine the role of the greenhouse gases CO2 , CH4 , and N2 O in the future long-term changes of the Earth's ozone layer, in particular in its recovery after reduction of anthropogenic discharges of chlorine and bromine compounds into the atmosphere.

Alexander Zadorozhny

2008-01-01

180

Greenhouse gases and recovery of the Earth's ozone layer  

Microsoft Academic Search

A numerical two-dimension zonally average interactive dynamical radiative-photochemical model of the atmosphere is used for investigation the role of the greenhouse gases CO2, CH4, and N2O in the recovery of the Earth's ozone layer after reduction of anthropogenic discharges in the atmosphere of chlorine and bromine compounds. The model allows calculating self-consistently diabatic circulation, temperature, gaseous composition of the troposphere

I. G. Dyominov; A. M. Zadorozhny

2004-01-01

181

Interaction quenches of Fermi gases  

SciTech Connect

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

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

2009-12-15

182

Process gases for laser welding  

Microsoft Academic Search

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

Mark Faerber; Joachim Berkmann

1997-01-01

183

How Greenhouse Gases Absorb Heat  

NSDL National Science Digital Library

Learners observe two model atmospheres -- one with normal atmospheric composition and another with an elevated concentration of carbon dioxide. These two model atmospheres are exposed to light energy from a sunny window or from a lamp. This activity will help learners understand that greenhouse gases in the atmosphere absorb and hold heat, relating to global warming and climate change.

History, American M.

2008-01-01

184

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

185

Infrared Radiation and Planetary Temperature  

NASA Astrophysics Data System (ADS)

Infrared radiative transfer theory, one of the most productive physical theories of the past century, has unlocked myriad secrets of the universe including that of planetary temperature and the connection between global warming and greenhouse gases.

Pierrehumbert, Raymond T.

2011-11-01

186

40 CFR 1065.750 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Analytical gases. 1065.750 Section 1065...CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Engine Fluids, Test Fuels, Analytical Gases and Other Calibration Standards...

2010-07-01

187

40 CFR 1065.750 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Analytical gases. 1065.750 Section 1065...CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Engine Fluids, Test Fuels, Analytical Gases and Other Calibration Standards...

2009-07-01

188

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

DOEpatents

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

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

1988-01-01

189

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

Microsoft Academic Search

Through three-dimensional global model studies on atmospheric composition and transport, we are improving our quantitative understanding of the origins and behavior of trace gases that affect Earth`s radiative energy balance and climate. We will focus, in this paper, on the simulations of three individual trace gases including CFC-11, methyl chloroform, and methane. We first used our chemical tracer model to

C. Y. J. Kao; E. Morz; X. Tie

1991-01-01

190

Landau damping in dilute Bose gases  

Microsoft Academic Search

Landau damping in weakly interacting Bose gases is investigated by means of perturbation theory. Our approach points out the crucial role played by Bose-Einstein condensation and yields an explicit expression for the decay rate of elementary excitations in both uniform and non-uniform gases. Systematic results are derived for the phonon width in homogeneous gases interacting with repulsive forces. Special attention

L. P. Pitaevskii; S. Stringari

1997-01-01

191

Ground state properties and applications of dipolar ultracold gases  

Microsoft Academic Search

This thesis contains a study of ultracold paramagnetic atoms or polar molecules characterized by a long-range anisotropic dipolar interaction. We particularly focus on two aspects of ultracold dipolar gases. In the first problem the ground state properties of dipolar Bose-Einstein condensates (BEC) are investigated. This problem has gained importance due to recent experimental advances in achieving a condensate of Chromium

Omjyoti Dutta

2008-01-01

192

Arc Thermal Recovery Speed in Different Gases and Gas Mixtures  

Microsoft Academic Search

One important requirement for circuit breakers when interrupting, short line fault currents is their ability to withstand the initial rise of the recovery voltage immediately after current zero. For gas flow breakers this capability is limited by the thermal recovery speed oI tne gas. The measured relative thermal recovery performance of various gases and their mixtures are reported. They differ

H. O. Noeske

1981-01-01

193

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

Microsoft Academic Search

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

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

1999-01-01

194

Evolution of trace gases and particles emitted by a chaparral fire in California  

Microsoft Academic Search

Biomass burning (BB) is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 ha prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009.

S. K. Akagi; J. S. Craven; J. W. Taylor; G. R. McMeeking; R. J. Yokelson; I. R. Burling; S. P. Urbanski; C. E. Wold; J. H. Seinfeld; H. Coe; M. J. Alvarado; D. R. Weise

2011-01-01

195

Quantum hydrodynamics of electron gases.  

PubMed

Electron gases in metals are described as quantum charged Newtonian viscous fluids experiencing Ohmic Darcy friction on the solid lattice ions as well. The dispersion relation of the electron acoustic waves is derived, which shows the existence of new quantum diffusion processes. The electric double layer near a metal surface is studied, which exhibits a new quantum oscillatory-decaying behavior different from the Friedel oscillations. PMID:20192305

Slavchov, Radomir; Tsekov, Roumen

2010-02-28

196

Atmospheric Chemistry and Greenhouse Gases  

SciTech Connect

Chapter 4 of the IPCC Third Assessment Report Climate Change 2001: The Scientific Basis. Sections include: Executive Summary 2414.1 Introduction 2434.2 Trace Gases: Current Observations, Trends and Budgets 2484.3 Projections of Future Emissions 2664.4 Projections of Atmospheric Composition for the 21st Century 2674.5 Open Questions 2774.6 Overall Impact of Global Atmospheric Chemistry Change 279

Ehhalt, D.; Prather, M.; Dentener, F.; Derwent, R.; Dlugokencky, Edward J.; Holland, E.; Isaksen, I.; Katima, J.; Kirchhoff, V.; Matson, P.; Midgley, P.; Wang, M.; Berntsen, T.; Bey, I.; Brasseur, G.; Buja, L.; Collins, W. J.; Daniel, J. S.; DeMore, W. B.; Derek, N.; Dickerson, R.; Etheridge, D.; Feichter, J.; Fraser, P.; Friedl, R.; Fuglestvedt, J.; Gauss, M.; Grenfell, L.; Grubler, Arnulf; Harris, N.; Hauglustaine, D.; Horowitz, L.; Jackman, C.; Jacob, D.; Jaegle, L.; Jain, Atul K.; Kanakidou, M.; Karlsdottir, S.; Ko, M.; Kurylo, M.; Lawrence, M.; Logan, J. A.; Manning, M.; Mauzerall, D.; McConnell, J.; Mickley, L. J.; Montzka, S.; Muller, J. F.; Olivier, J.; Pickering, K.; Pitari, G.; Roelofs, G.-J.; Rogers, H.; Rognerud, B.; Smith, Steven J.; Solomon, S.; Staehelin, J.; Steele, P.; Stevenson, D. S.; Sundet, J.; Thompson, A.; van Weele, M.; von Kuhlmann, R.; Wang, Y.; Weisenstein, D. K.; Wigley, T. M.; Wild, O.; Wuebbles, D.J.; Yantosca, R.; Joos, Fortunat; McFarland, M.

2001-10-01

197

Hot and Cold Ideal Gases  

NSDL National Science Digital Library

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

Timberlake, Todd

2010-07-01

198

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

199

NRC symposium explores links between greenhouse gases, stratospheric ozone  

SciTech Connect

Two important climatic issues stratospheric ozone depletion and greenhouse gas increase and the apparent connection between them led to the holding in March 1988 of a Joint Symposium on Ozone Depletion, Greenhouse Gases and Climate Change. This symposium was primarily concerned with the linkages between ozone depletion and increasing greenhouse gases and with their combined effect in causing climate change to occur on a global scale. The presentations review the current state of knowledge about stratospheric ozone depletion, discuss the probable effect of predicted greenhouse gas increase on future ozone trends, summarize observational data on changing atmospheric chemistry and associated atmospheric temperatures, and describe the continuing effort to model and predict future scenarios of climatic change relative to ozone and greenhouse gases in both the stratosphere and the troposphere.

Not Available

1989-04-01

200

Chemical and radiative effects of methane. Final report, December 1990September 1993  

Microsoft Academic Search

The purpose of this report is to better quantify the radiative forcing by atmospheric methane and other greenhouse gases. More specifically, the following issues will be addresed: The direct radiative impact of increasing concentrations of green house gases including CO2, CH4, N2O and the CFCs; The impact of changing concentrations of trace gases emitted at the surface level on the

C. Granier; S. Madronich; G. P. Brasseur

1995-01-01

201

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

Microsoft Academic Search

The role of direct radiative forcing of desert dust aerosol in the change from wet to dry climate observed in the African Sahel region in the last half of the twentieth century is investigated using simulations with an atmospheric general circulation model. The model simulations are conducted either forced by the observed sea surface temperature (SST) or coupled with the

Masaru Yoshioka; Natalie M. Mahowald; Andrew J. Conley; William D. Collins; David W. Fillmore; Charles S. Zender; Dani B. Coleman

2007-01-01

202

Radiation Cataract  

NASA Astrophysics Data System (ADS)

These studies provide an opportunity to study the effects of low-dose radiation exposure and the influence(s) of genetic radiosensitivity in a rodent model that has great relevance and similarity to human response to radiation exposure and determination of appropriate human exposure guidelines. Futhermore, any extension of the presumed radiation cataract threshold in this animal model to lower doses is likely to be important to the development of appropriate guidelines for national space radiation risk policy.

Kleiman, Norman; Hall, Eric; Brenner, David; Lieberman, Howard; Smilenov, Lubomir

203

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

Microsoft Academic Search

Experiments aboard the Ulysses spacecraft discovered quasi-periodic bursts of relativistic electrons and of radio emissions with ~40-min period (QP-40) from the south polar direction of Jupiter in 1992 February. Such polar QP-40 burst activities were found to correlate well with arrivals of high-speed solar winds at Jupiter. We advance the physical scenario that the inner radiation belt (IRB) within a

Yu-Qing Lou; Chen Zheng

2003-01-01

204

Biomethanation of biomass pyrolysis gases  

NASA Astrophysics Data System (ADS)

The development of the biological methanation process and conditions for maximum performane were studied. Gasification processes have the potential to produce a synthesis gas from biomass. The advantage of such processes is that all organic components of the biomass may be converted to synthesis gas. However, this low Btu value gas is of limited use as a fuel gas. To convert the synthesis gas into pipeline quality methane, a methanation process is necessary. A more economical alternative to catalytic methanation at high temperature and pressure is the utilization of a biological system to carry out the conversion of biomass pyrolysis gases to methane.

Tracy, C. A.; Ashare, E.

1981-08-01

205

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

206

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

207

Filter for cleaning hot gases  

SciTech Connect

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

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

1981-10-20

208

Reservoir gases exhibit subtle differences; Part 4  

SciTech Connect

This segment of the reservoir fluids series describes the characteristics of wet and dry gases. At an initial producing gas-oil ratio greater than 15,000 scf/STB, engineers can treat the reservoir fluid as a wet gas. Gases with initial producing gas-oil ratios greater than 100,000 scf/STB can be treated as dry gases. Retrograde behavior has been observed in gases with initial producing gas-oil ratios greater than 150,000 scf/STB. The quantity of retrograde liquid in the reservoir is very small for gases this lean. If a gas has enough heavy components to release condensate at the surface, the gas will probably release some amount of condensate in the reservoir. This implies few true wet gases exist (liquid at the surface but no liquid in the reservoir).

McCain, W.D. Jr. (S.A. Holditch and Associates, College Station, TX (United States)); Piper, L.D. (Texas A M Univ., College Station, TX (United States))

1994-03-01

209

Removal of acid gases in dry scrubbing of hot gases  

SciTech Connect

This patent describes a method for the removal of sulfur oxide gases from a flue gas containing the same. The method comprising: dispersing finely-divided dry hydrated lime in a humid inert gas having a relative water vapor pressure higher than the fugacity of at least a monomolecular layer of water thereby adsorbed on the hydrated lime; bringing the dispersed hydrated lime and adsorbed water into contact with gaseous carbon dioxide thereby converting surfaces of the lime to calcium carbonate; flowing the dispersion of so-carbonated lime into admixture and reactive contact with the fluid gas to form calcium sulfite and sulfates from sulfur oxides in the flue gas; subsequently removing solids including reacted calcium sulfite and sulfate and excess reactants from the so-treated flue gas and discharging so-purified flue gas to the atmosphere.

Lerner, B.J.

1989-09-12

210

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

211

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.

212

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

213

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

Microsoft Academic Search

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

Guadalupi

1977-01-01

214

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

215

Voluntary Reporting of Greenhouse Gases Archive  

EIA Publications

The Voluntary Reporting of Greenhouse Gases Program established a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., can report to the EIA, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

Joe Ayoub

216

Detection of toxic gases using cermet sensors  

Microsoft Academic Search

New technologies are needed for detection and identification of gaseous species in near-real time. Voltammetry, applied to cermet electrochemical cell microsensors, was shown in this study to be promising in its ability to discern and quantify gases. The miniature cermet cells were fabricated from ceramic, metallic, and metal oxide components, and reacted uniquely with gases and mixtures in the atmosphere.

Laura R. Skubal; Michael C. Vogt

2004-01-01

217

Adsorption of gases in carbon nanotubes  

Microsoft Academic Search

This work addresses the physical adsorption of gases in carbon nanotubes. In the confining environment of nanotube bundles, adsorbed atoms exhibit behavior characteristic of 1, 2, and 3 dimensions as a function of thermodynamic parameters, geometry, and microscopic variables. Many body interactions among quasi-1D phases of gases adsorbed within carbon nanotubes and the corresponding implications for condensation transition are investigated.

Milen Kalushkov Kostov

2003-01-01

218

Magnetic Pumps for Corrosive Gases and Liquids  

Microsoft Academic Search

Small, completely sealed, magnetically operated pumps have been constructed for use in circulation of corrosive gases. Successful and extended use has been obtained with gases such as uranium hexafluoride and hydrogen fluoride at pressures up to 175 psig and 100°C. Pumping characteristics with respect to air at atmospheric suction pressure are given.

F. D. Rosen

1953-01-01

219

Method of processing of waste gases  

Microsoft Academic Search

A method is described of processing of waste gases containing hydrogen fluoride and silicon tetrafluoride or hydrogen fluoride, silicon tetrafluoride and sulfur dioxide by absorption of hydrogen fluoride and silicon tetrafluoride or hydrogen fluoride, silicon tetrafluoride and sulfur dioxide from waste gases by water solutions containing ammonium compounds such as ammonium carbonate, ammonium bicarbonate and ammonium fluoride. In addition to

V. S. Kalach; L. I. Burlakova

1976-01-01

220

Density functional theory for fermionic atom gases  

Microsoft Academic Search

We will show how Kohn-Sham density-functional theory (DFT), which forms the basis of most electronic structure calculations in material science, can be applied to ultracold atomic gases in optical lattices. We present the derivation of an exchange correlation functional for atomic gases and show first applications within a local spin density approximation. In particular we will show that the local

Matthias Troyer; Ping Nang Ma; Sebastiano Pilati; Xi Dai

2011-01-01

221

BOOK REVIEW: Plasma Kinetics in Atmospheric Gases  

Microsoft Academic Search

The book Plasma Kinetics in Atmospheric Gases is a worthwhile contribution to the basic phenomena in nitrogen, oxygen and other atmospheric gases. It contains basic introductory chapters on relaxation in translational, rotational (short) and vibrational (extensive) distribution and on the physics of electron excitation and electron distribution functions. In the latter, electron beam excitation (i.e. high electron energies) are included.

M. Capitelli; C. M. Ferreira; B. F. Gordiets; A. I. Osipov

2001-01-01

222

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

NASA Astrophysics Data System (ADS)

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

Li, J.; Barker, H. W.

2005-02-01

223

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

Microsoft Academic Search

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

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

1997-01-01

224

Handling of Radiation Accidents.  

National Technical Information Service (NTIS)

The book deals with one of the most important questions in the practice of radiation safety: the radiation hazards. Chapter I ''Radiation hazards - fundamental concepts, determination and examples'' gives the definition of the concept ''hazard'' and the c...

M. A. Mikhajlov G. Vasilev

1978-01-01

225

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

Microsoft Academic Search

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

Jingle Liu; Xi-Cheng Zhang

2011-01-01

226

Coherent VUV Generation by Four-Wave Mixing Processes in Inert Gases  

Microsoft Academic Search

Coherent VUV radiation at 1215 (Hydrogoen Ly-(alpha)), 1259, 1261 and 1254 (ANGSTROM), etc., has been generated by means of nonlinear mixing of inert gases. This dissertation consists of three major parts: the first part presents a theoretical study on maximum conversion due to the spatial mode effect of the input laser, the second part describes the experimental findings of the

Yun Mui Yiu

1983-01-01

227

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

Microsoft Academic Search

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

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

2007-01-01

228

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

229

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.

2013-01-01

230

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

231

Impact degassing of water and noble gases from silicates  

NASA Astrophysics Data System (ADS)

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

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

232

Present state of eb removal of so2 and nox from combustion flue gases in Brazil  

NASA Astrophysics Data System (ADS)

Environmental problems caused by the increased world energy demands are becoming of growing importance and Brazil is now starting to set limits to the emission of toxic gases. The development of technologies for removal of these gases are therefore necessary and this work shows the present state of the technology of SO2 and NOX removal by electron beam irradiation in Brazil. Data concerning the increasing energy demand in Brazil and the environmental governmental measures are presented, along with the design and implementation of a laboratory pilot plant for the electron beam flue gases removal process located at IPEN-CNEN/SP.

Poli, D. C. R.; Osso, J. A.; Rivelli, V.; Vieira, J. M.; Lugão, A. B.

1995-09-01

233

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

234

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

NASA Astrophysics Data System (ADS)

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.

235

41 CFR 50-204.70 - Compressed gases.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 true Compressed gases. 50-204.70...Mists § 50-204.70 Compressed gases. The in-plant handling, storage, and utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or...

2010-07-01

236

41 CFR 50-204.70 - Compressed gases.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Compressed gases. 50-204.70...Mists § 50-204.70 Compressed gases. The in-plant handling, storage, and utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or...

2009-07-01

237

41 CFR 50-204.70 - Compressed gases.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Compressed gases. 50-204.70...Mists § 50-204.70 Compressed gases. The in-plant handling, storage, and utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or...

2013-07-01

238

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

Code of Federal Regulations, 2011 CFR

...2 2011-10-01 2011-10-01 false Class 2 (gases) material cylinders. 174.201... CARRIAGE BY RAIL Detailed Requirements for Class 2 (Gases) Materials § 174.201 Class 2 (gases) material cylinders. (a)...

2011-10-01

239

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

Code of Federal Regulations, 2012 CFR

...2 2012-10-01 2012-10-01 false Class 2 (gases) material cylinders. 174.201... CARRIAGE BY RAIL Detailed Requirements for Class 2 (Gases) Materials § 174.201 Class 2 (gases) material cylinders. (a)...

2012-10-01

240

Process for Producing Catalysts for Cleaning Industrial-Waste Gases.  

National Technical Information Service (NTIS)

This invention concerns catalysts which are effective for removing nitrogen oxides (NO/sub x/), carbon monoxide (CO) and hyrocarbons (HC) from automobile exhaust gases, waste gases from fixed combustion systems and waste gases from chemical plants. The pr...

I. Shimizu K. Abe

1983-01-01

241

40 CFR 600.108-08 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Analytical gases. 600.108-08 Section 600... ENERGY POLICY FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF MOTOR VEHICLES...Procedures § 600.108-08 Analytical gases. The analytical gases for...

2013-07-01

242

Biomass Burning and the Production of Greenhouse Gases.  

National Technical Information Service (NTIS)

Biomass burning is a source of greenhouse gases, carbon dioxide, methane, and nitrous oxide. In addition, biomass burning is a source of chemically active gases, including carbon monoxide, nonmethane hydrocarbons, and nitric oxide. These gases, along with...

J. S. Levine

2004-01-01

243

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

244

Imported malaria*  

PubMed Central

There have been 4 waves of imported malaria in the USA. They occurred during the colonization of the country and during the Second World War, the UN Police Action in Korea, and the Viet-Nam conflict. The first 3 episodes are briefly described and the data on imported malaria from Viet-Nam are discussed in detail. Endemic malaria is resurgent in many tropical countries and international travel is also on the rise. This increases the likelihood of malaria being imported from an endemic area and introduced into a receptive area. The best defence for countries threatened by imported malaria is a vigorous surveillance programme. The principles of surveillance are discussed and an example of their application is provided by a description of the methods used to conduct surveillance of malaria in the USA.

Schultz, Myron G.

1974-01-01

245

Heparin Importation  

Center for Drug Evaluation (CDER)

... order to ensure that batches of imported heparin continue to meet regulatory standards, FDA is requiring that all lots of Heparin Sodium be required ... More results from www.fda.gov/drugs/guidancecomplianceregulatoryinformation/importsandexportscompliance

246

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

NASA Astrophysics Data System (ADS)

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

Lou, Yu-Qing; Zheng, Chen

2003-09-01

247

Oil imports  

Microsoft Academic Search

The current status of oil-import policy focuses on world pressure for the U.S. to reduce its import level in exchange for which six participants at the economic summit meeting promised to try to improve the market for U.S. exports by stimulating their own economies. The author reviews, in addition to these pressures, problems of legislative barriers, the effects of the

1978-01-01

248

NO2Assisted Soot Regeneration Behavior in a Diesel Particulate Filter with Heavy-Duty Diesel Exhaust Gases  

Microsoft Academic Search

A major concern in operating a diesel engine is how to reduce the soot emission from the exhaust gases, as soot has a negative effect on both human health and the environment. More stringent emission regulations make the diesel particulate filter (DPF) an indispensable after-treatment component to reduce diesel soot from exhaust gases. The most important issue in developing an

Jong Hun Kim; Man Young Kim; Hyong Gon Kim

2010-01-01

249

Light Collection in Liquid Noble Gases  

ScienceCinema

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

250

The biological and toxicological activity of gases and vapors.  

PubMed

A large amount of data on the biological and toxicological activity of gases and vapors has been collected from the literature. Processes include sensory irritation thresholds, the Alarie mouse test, inhalation anesthesia, etc. It is shown that a single equation using only five descriptors (properties of the gases and vapors) plus a set of indicator variables for the given processes can correlate 643 biological and non-lethal toxicological activities of 'non-reactive' compounds with a standard deviation of 0.36 log unit. The equation is scaled to sensory irritation thresholds obtained by the procedure of Cometto-Muñiz, and Cain provides a general equation for the prediction of sensory irritation thresholds in man. It is suggested that differences in biological/toxicological activity arise primarily from transport from the gas phase to a receptor phase or area, except for odor detection thresholds where interaction with a receptor(s) is important. PMID:19913608

Abraham, Michael H; Sánchez-Moreno, Ricardo; Gil-Lostes, Javier; Acree, William E; Cometto-Muñiz, J Enrique; Cain, William S

2009-11-12

251

The Biological and Toxicological Activity of Gases and Vapors  

PubMed Central

A large amount of data on the biological and toxicological activity of gases and vapors has been collected from the literature. Processes include sensory irritation thresholds, the Alarie mouse test, inhalation anesthesia, etc. It is shown that a single equation using only five descriptors (properties of the gases and vapors) plus a set of indicator variables for the given processes can correlate 643 biological and non-lethal toxicological activities of ‘non-reactive’ compounds with a standard deviation of 0.36 log unit. The equation is scaled to sensory irritation thresholds obtained by the procedure of Cometto-Muñiz, and Cain, and provides a general equation for the prediction of sensory irritation thresholds in man. It is suggested that differences in biological/toxicological activity arise primarily from transport from the gas phase to a receptor phase or area, except for odor detection thresholds where interaction with a receptor(s) is important.

Sanchez-Moreno, Ricardo; Gil-Lostes, Javier; Acree, William E.; Cometto-Muniz, J. Enrique; Cain, William S.

2010-01-01

252

Numerical studies of granular gases  

NASA Astrophysics Data System (ADS)

In this dissertation, we study velocity distributions in granular gases. For granular systems at low density, kinetic theory reduces to the Boltzmann equation which is based on the assumption of molecular chaos. At large velocity scales, stationary solutions with power-law tails, f( v) ˜ v--sigma, have been derived from the Boltzmann equation for spatially homogeneous granular systems [6]. The behavior of power-law tail is complete generic, holding for arbitrary dimension, arbitrary collision rules, and general collision rates. We find the non-Maxwellian steady states using event-driven molecular dynamics simulations. Firstly, power-law steady states are observed in driven systems where energy is injected rarely at large velocity scale V . The range of power-law tail shrinks when we increase the heating-dissipation ratio NINC , where NI and NC are number of injections and number of collisions, respectively. Then a crossover from a power-law to a stretched exponential distribution is developed when the heating-dissipation ratio NINC is close to 1. It is the energy cascade from a few energetic particles to the overwhelming majority of slowly moving particles that causes the non-Maxwellian velocity distributions. Steady states with power-law tail are robust as long as the injection velocity scale V is essentially separated from the typical velocity scale v0. These steady states are shown to exist for a wide range of number densities, different combinations of injection velocities and injection rates. The injection velocity scale V, the typical velocity scale v0, and the injection rate per particle are related by energy balance. This energy balance relation is confirmed by data collapse of velocity distributions for various choices of parameters.

Kang, Wenfeng

253

Radiation stability of fluorite-type nuclear oxides  

NASA Astrophysics Data System (ADS)

Oxides with the fluorite-type structure are radiation tolerant materials. They are widely used or envisaged in hostile nuclear environments, such as nuclear fuels or inert transmutation matrices for actinide burning. Study of the radiation stability of this class of solids in various radiative fields is of major importance. Two issues which may affect the stability of materials are considered in this work: the production of radiation damage (ballistic contribution); the modification of the matrix composition by doping (chemical contribution). Both contributions may drastically affect the solid stability. Urania and zirconia single crystals were chosen as fluorite-type canonical systems. They were implanted with low-energy inert gases (He or Xe). The damage in-growth, due to both ballistic and chemical contributions, was investigated by in situ RBS/C experiments in the channelling mode and TEM. Two main steps in the disordering kinetics were observed for both inert gases. Relevant key parameters were found to be: the number of displaced lattice atoms created by the slowing-down of energetic ions during the implantation process; the concentration of noble gas atoms in the solid which cause the formation of large stress fields surrounding gas aggregates.

Garrido, Frédérico; Vincent, Laetitia; Nowicki, Lech; Sattonnay, Gaël; Thomé, Lionel

2008-06-01

254

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

255

Integration of natural gases in hydrocarbon systems of the northern Gulf of Mexico Basin  

SciTech Connect

Associated and non-associated natural gases of the northern Gulf of Mexico Basin have been characterized as part of Exxon`s multidisciplinary study of hydrocarbon source, maturation and migration. Analyses of over 600 natural gases were integrated within the hydrocarbon (HC) system context provided by evaluation of more than 2000 reservoired oils, 1200 HC-bearing sea bottom drop cores, and extensive source rock data, all synthesized within a geologic framework developed from 2-D and 3-D seismic. The molecular and isotopic compositions of gases can vary due to type of organic matter and level of maturity of the source, mixing with biogenic methane, and biodegradation. Organic matter type is a primary control on the compositions of natural gases, as documented by the close correspondence of gas compositions to HC systems defined from oil and source rock characterization. For example, the predominance of relatively dry gas on the Texas shelf primarily reflects generation from a terrestrial, gas-prone source. The recognition of significant source controls on gas composition has important implications to evaluation of gas maturity and inferred timing of generation. Complications from widespread occurrence of biogenic gas are incorporated in gas interpretations. Integration of these gas and oil data strongly supports the concept that most associated thermogenic gases have been cogenerated with oils within the normal oil window. On the slope, large seeps contain early mature oils and abundant wet thermogenic gases, documenting comigration and suggesting that the two have a common origin. In contrast, high maturity gases are distinctly absent.

James, A.T.; Wenger, L.M. [Exxon Production Research Company, Houston, TX (United States); Hood, K.C. [Exxon Exploration Company, Houston, TX (United States)

1996-08-01

256

Radiation protection.  

PubMed

One of radiologic technologists' most important professional obligations is protecting patients, other members of the health care team, the public and themselves from as much radiation-related harm as possible while also maximizing the screening, diagnostic and therapeutic potential of ionizing radiation. This article reviews the different types of radiation dose and how radiation affects the body. Patient shielding, personnel dosimeters and area monitors are discussed, along with beam collimation and filtration. The author also describes protocols to protect pregnant patients and pregnant technologists. PMID:17519374

Brusin, Joyce Helena

257

40 CFR 1065.750 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

... Engine Fluids, Test Fuels, Analytical Gases and...Constituent Purified synthetic air 1 Purified N2...analyzer: (i) FID fuel . Use FID fuel with a stated H2... , balance purified synthetic air and/or N2...

2013-07-01

258

Advanced Global Atmospheric Gases Experiment (AGAGE).  

National Technical Information Service (NTIS)

The Advanced Global Atmospheric Gases Experiment (AGAGE) is an ongoing research project, for which the work carried out by the Scripps Institution of Oceanography. Due to the need to complete AGAGE activities specifically funded under NAGW-2034 that had b...

R. F. Weiss

1998-01-01

259

REGIONAL DEPOSITION OF INHALED REACTIVE GASES  

EPA Science Inventory

A critical concept in inhalation toxicology involves the determination of dose as the first component for providing a perspective to judge the applicability of various toxicological results to human exposure conditions. Available experimental data for reactive gases were reviewed...

260

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

261

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

262

Ionizing Potential Waves in Preionized Gases.  

National Technical Information Service (NTIS)

A theory is presented to describe the advance of ionizing potential waves in preionized gases in nonuniform fields. The theory is based on the use of similarity and related arguments to bypass complicated mathematics and derive scaling relationships for w...

R. F. Fernsler

1983-01-01

263

Toxicity of Pyrolysis Gases from Elastomers.  

National Technical Information Service (NTIS)

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 ru...

A. N. Solis C. J. Hilado D. A. Kourtides J. A. Parker K. L. Kosola

1977-01-01

264

40 CFR 91.312 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...purified nitrogen. However, the manufacturer must be consistent in the choice of diluent (zero air or purified nitrogen) between the calibration and span gases...The use of precision blending devices (gas dividers) to...

2013-07-01

265

40 CFR 90.312 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...purified nitrogen. However, the manufacturer must be consistent in the choice of diluent (zero air or purified nitrogen) between the calibration and span gases...The use of precision blending devices (gas dividers) to...

2013-07-01

266

Use of Offsets to Reduce Greenhouse Gases.  

National Technical Information Service (NTIS)

Discussions about reducing greenhouse gases often focus on limiting the use of fossil fuels to generate electricity or power cars and trucks, yet a variety of other actionsincluding disposing of waste in different ways, changing methods of farming, and le...

2009-01-01

267

Greenhouse gases from animal husbandry: mitigation options  

Microsoft Academic Search

Abatement strategies for direct emissions of greenhouse gases from animal husbandry are discussed. The reduction options are\\u000a divided into preventive and `end of pipe' options. Preventive measures reduce either the carbon and nitrogen input into the\\u000a system of animal husbandry or their output from the system, respectively. `End of pipe' measures reduce the formation of greenhouse\\u000a gases from carbon and

Joachim Clemens; Heinz-Jürgen Ahlgrimm

2001-01-01

268

Quantum Polarization Spectroscopy of Ultracold Spinor Gases  

SciTech Connect

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

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

2007-03-09

269

Analysis of electron interactions in dielectric gases  

SciTech Connect

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

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

2007-01-15

270

Evolution of minor trace gases and isotopic ratios in Titan's stratosphere using CIRS/Cassini spectra  

NASA Astrophysics Data System (ADS)

The Cassini/Huygens mission has extensively studied Titan's environment and for the first time provided temporal and spatial variability information since 2004. Here, we focus on the stratosphere with its complex organic chemistry by using the wealth of the infrared spectra retrieved by the Composite Infrared Spectrometer (CIRS) consisting of two interferometers, aboard Cassini (1). These data cover a large part of Titan's globe in high, medium and low resolution (0.5cm-1, 2.5cm-1 and 15.5cm-1 respectively). CIRS has mapped the stratosphere in more than 70 flybys so far either in downward or horizontal viewing in the range 10-1400cm-1. First, we import large FP4 averages (1100-1400cm-1), using the nu4 methane band as a thermometer, into an inverse algorithm (2, 3) to retrieve the corresponding vertical temperature profile and apply it to our line-by-line radiative tranfer code (RTC) (4, 5). Then, through an iterative best-fit process, we construct a model spectrum fitting the relative FP3 average (600-1100cm-1). Eventually, we infer the abundances of each spectroscopic query trace gases and we can study temporal and spatial evolutions (6). We have upgraded our recipe by adopting recent laboratory spectroscopic results (7, 8) and the aerosol influence (9). The upgraded RTC with the breadth of CIRS recordings help us study the infrared signature of Titan's stratospheric weak trace gases (C6H6, C2HD, HC3N). Moreover, we look for new isotopologues (12C13CH6, H13CCCN, H12CC13CN, H12CC13CN, DC14N, H13CN, 13C16O2, C18O16O, C17O16O, 13C17O16O, 13C18O2, 13C18O16O, C18O16O) and calculate 13C/12C, D/H, 15N/14N, 17O/16O and 18O/16O isotopic ratios throughout Titan's atmosphere. We compare our results to other publications (10-14) and give upper limits for the weakest species. Since the stratospheric composition varies over a Saturnian year (6), the trace gases abundances and their isotopologues help us understand Titan's atmospheric dynamics and photochemical evolution giving clues about their sources and sinks.

Bampasidis, G.; Coustenis, A.; Achterberg, R. K.; Jennings, D. E.; Nixon, C. A.; Vinatier, S.; Lavvas, P.; Carlson, R.; Teanby, N.; Flasar, F. M.; Guandique, E.; Stamogiorgos, S.

2012-04-01

271

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...

272

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

273

Importance timing  

NASA Astrophysics Data System (ADS)

Bayesian evidence Z = ? L(x)d?(x) is defined as likelihood L integrated over prior ?, and is often computed in that form -- with nested sampling as the preferred algorithm for passing from prior to posterior in large or complicated applications. However, a user may suspect that some locations x are more useful than others, and wish to guide the computation by using a suitable weight function w(x). In conventional importance sampling, such weights are incorporated by re-writing Z as ?(L/w)(wd?), using a weighted prior w? and correspondingly de-weighted likelihood L/w. Unfortunately, w cannot be updated during a run without altering the likelihood surfaces (which nested sampling requires to be fixed). Also, the normalization ? wd? must be known if the value of Z is to be retrieved. Importance timing removes those disadvantages by preserving the likelihood unchanged. Excess prior weight w is cancelled, not through L, but by adjusting the rate of the MCMC clock which defines termination of a trial exploration. This preserves the evidence value and enables the weights to be (slowly) learned as iterations proceed.

Skilling, John

2013-08-01

274

Method of producing pyrolysis gases from carbon-containing materials  

Microsoft Academic Search

This patent describes a method for producing pyrolysis gases from carbon-containing materials. The method comprising: pyrolyzing the carbon-containing materials in a gasification reactor in order to form pyrolysis gases therefrom. The pyrolysis gases having residual tar and oil byproducts entrained therein; passing the pyrolysis gases from the gasification reactor into and through a catalytic reactor having a fluidized bed therein

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

1989-01-01

275

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

276

Radiative heating in contrail cirrus  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

277

Air Pollution, Greenhouse Gases and Climate Change  

NASA Astrophysics Data System (ADS)

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

Ramanathan, V.

2007-12-01

278

Ab initio Calculations of Solvation Processes in Volcanic Gases  

NASA Astrophysics Data System (ADS)

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

Lemke, K.; Seward, T.

2006-12-01

279

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

280

Pulse Discharge in Mixing Layer of Reacting Gases  

NASA Astrophysics Data System (ADS)

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

Leonov, Sergey; Isaenkov, Yuri; Shneider, Michail

2008-10-01

281

Interpretation of arterial blood gases  

Microsoft Academic Search

Arterial blood gas analysis is a frequently used and extremely useful clinical tool. Doctors of all levels understand the results to varying degrees. This article aims to explain some of the more important points and thus help with interpretation of results. Not all of the results produced by a blood gas analyser are measured; the machine calculates some itself. The

Claire Baylis; Chris Till

2009-01-01

282

The importance of the Montreal Protocol in protecting climate.  

PubMed

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

2007-03-08

283

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.

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

2007-01-01

284

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

285

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

NASA Astrophysics Data System (ADS)

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

Kroesen, Gerrit

2006-05-01

286

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

287

Condensate fluctuations of interacting Bose gases within a microcanonical ensemble  

NASA Astrophysics Data System (ADS)

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

2011-05-01

288

Condensate fluctuations of interacting Bose gases within a microcanonical ensemble.  

PubMed

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. PMID:21728515

Wang, Jianhui; He, Jizhou; Ma, Yongli

2011-05-31

289

Atmospheric Radiation Measurement Program facilities newsletter, July 2001  

Microsoft Academic Search

Global Warming and Methane--Global warming, an increase in Earth's near-surface temperature, is believed to result from the buildup of what scientists refer to as ''greenhouse gases.'' These gases include water vapor, carbon dioxide, methane, nitrous oxide, ozone, perfluorocarbons, hydrofluoro-carbons, and sulfur hexafluoride. Greenhouse gases can absorb outgoing infrared (heat) radiation and re-emit it back to Earth, warming the surface. Thus,

Holdridge

2001-01-01

290

Hot exhaust gases with passive FTIR emission spectroscopy  

NASA Astrophysics Data System (ADS)

Passive FTIR emission spectroscopy using a commercial medium resolution instrument with a telescope has been applied to analyze the hot exhaust gases of various combustion sources, such as industrial and building smoke stacks, aircraft engines, flares, and forest fires. To interpret the remotely measured spectra a multi-layer, line-by-line spectra retrieval software using the molecular spectral databases HITRAN and HITEMP has been developed, validated and successfully used to determine the exhaust gas temperatures and the concentrations of CO2, H2O, CO, N2O, CH4, NO, NO2, SO2, and HCl for different combustion conditions of the sources. In this paper the feasibility and the setup of passive IR measurements, the basic theory of radiative transfer and special features of the commercially available spectra analysis code are described. In addition, the results of the different measurement applications are summarized.

Heland, Joerg; Schaefer, Klaus; Haus, Rainer

1998-12-01

291

Density Fluctuations in Uniform Quantum Gases  

SciTech Connect

Analytical expressions are given for the static structure factor S(k) and the pair correlation function g(r) for uniform ideal Bose-Einstein and Fermi-Dirac gases for all temperatures. In the vicinity of Bose Einstein condensation (BEC) temperature, g(r) becomes long ranged and remains so in the condensed phase. In the dilute gas limit, g(r) of bosons and fermions do not coincide with Maxwell-Boltzmann gas but exhibit bunching and anti-bunching effect respectively. The width of these functions depends on the temperature and is scaled as {radical}(inverse atomic mass). Our numerical results provide the precise quantitative values of suppression/increase (antibunching and bunching) of the density fluctuations at small distances in ideal quantum gases in qualitative agreement with the experimental observation for almost non-trapped dilute gases.

Bosse, J. [Institute for Theoretical Physics, Freie Universitaet Berlin (Germany); Pathak, K. N. [Department of Physics, Panjab University, Chandigarh (India); Singh, G. S. [Department of Physics, Indian Institute of Technology, Roorkee (India)

2011-12-12

292

Methanol production from fermentor off-gases  

NASA Astrophysics Data System (ADS)

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

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

293

Global radiative forcing from contrail cirrus  

NASA Astrophysics Data System (ADS)

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

Burkhardt, Ulrike; Kärcher, Bernd

2011-04-01

294

Ultracold Lattice Gases with Periodically Modulated Interactions  

NASA Astrophysics Data System (ADS)

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

Rapp, Ákos; Deng, Xiaolong; Santos, Luis

2012-11-01

295

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

296

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

PubMed

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

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

2012-04-04

297

Optical properties of explosive-driven shock waves in noble gases  

SciTech Connect

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

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

1983-01-01

298

Influence of Thermal Blackbody Radiation on the Evolution of a Cold Rydberg Gas  

Microsoft Academic Search

Cold Rydberg gases are dynamical systems subject to multiple state-changing and ionizing collision processes. Blackbody radiation can modify the dynamics of Rydberg gases in various ways. The Rydberg atoms undergo thermal redistribution and ionization, affecting the bound-state redistribution and (partial) plasma formation. Plasma electrons in the presence of ion fields can also couple to the blackbody radiation field. We present

A. Walz-Flannigan; J. R. Guest; J.-H. Choi; G. Raithel

2004-01-01

299

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

300

Infrared emission spectroscopy of glow discharge formed in low pressure atmospheric gases  

NASA Astrophysics Data System (ADS)

Laboratory study was conducted on the molecular and atomic emissions which are considered detectable in the IR radiative background of the upper atmosphere. The IR spectra of glow discharge emission formed in air and other atmospheric constituent gases of 0.1-Torr pressure and a 30-m long column were surveyed using the technique of Fourier spectroscopy. Several features hitherto unobserved were detected in our survey study.

Sakai, H.; Hansen, P.; Esplin, M.; Johansson, R.; Peltola, M.; Strong, J.

1982-01-01

301

Greenhouse gases and future long?term changes in the stratospheric temperature and the ozone layer  

Microsoft Academic Search

A numerical two?dimensional (2D) interactive dynamical–radiative–photochemical model including aerosol physics is used to examine the expected long?term changes in stratospheric temperature and the Earth's ozone layer due to anthropogenic pollution of the atmosphere by the greenhouse gases CO2, CH4 and N2O. The model time?dependent runs were made for the period from 1975 to 2050. The results of the calculations show

I. G. Dyominov; A. M. Zadorozhny

2008-01-01

302

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

303

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

304

Climate change and trace gases.  

PubMed

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

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

2007-07-15

305

Mass Spectrometer for the Analyses of Gases.  

National Technical Information Service (NTIS)

A 6-in-radius, 60 exp 0 magnetic-sector mass spectrometer (designated as the MS-200) has been constructed for the quantitative and qualitative analyses of fixed gases and volatile organics in the concentration range from 1 ppM (by volume) to 100%. A parti...

J. R. Ferguson E. R. Rogers

1980-01-01

306

Heat Conductivity of Polyatomic and Polar Gases  

Microsoft Academic Search

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

E. A. Mason; L. Monchick

1962-01-01

307

Circulating Pump for Ultrapure or Toxic Gases.  

National Technical Information Service (NTIS)

A small, stainless steel, Roots-type pump for gases is described. The pump employs helium leak tight rotary seals which render it suitable for use in ultrahigh vacuum gas handling systems. A throughput (at atmospheric pressure of 100 liters/min has been m...

C. C. Leiby E. C. Dunton

1972-01-01

308

Spectra and Latent Energy in Flame Gases  

Microsoft Academic Search

PROF. W. T. DAVID in the first paragraph of his letter under this title1 makes two points about the afterglow in the gases from names or explosive reactions; the first that the temperatures determined by the sodium flame reversal method are too high, compared presumably with the platinum resistance method, the second that `long-lived' luminous products account for a considerable

A. Egerton; A. R. Ubbelohde

1934-01-01

309

Gases Released by Surface Flashover of Insulators.  

National Technical Information Service (NTIS)

The gases released by surface flashovers on alumina ceramics, Pyrex glass, and quartz, using 20- mu s voltage pulses were investigated using an ion pumped metal vacuum system. Appreciable quantities of gas were measured (approximately 10 sup -6 torr-liter...

H. C. Miller R. J. Ney

1987-01-01

310

Removal of acidic gases from gaseous mixtures  

Microsoft Academic Search

A British improvement of a process for removing acidic gases (such as carbon dioxide and hydrogen sulfide) from gaseous mixtures in a 2-step MEA or DEA arrangement maintains substantially constant concentrations of the volatile reagent in the regenerated solutions entering the 1st and 2nd absorption zones, controls the flow of stripping steam to each regeneration zone (minimizing the flow to

Thirkell

1973-01-01

311

Electrical breakdown in low pressure gases  

Microsoft Academic Search

The paper presents the results of investigation of the electrical breakdown in low pressure gases when the secondary electrons released from the cathode play the dominant role in the initiation of electrical breakdown. The secondary electrons are created by the charged and neutral species formed during the previous breakdown and discharge as well as by ?-rays. Electrical breakdown investigations are

Momcilo M Pejovic; Goran S Ristic; Jugoslav P Karamarkovic

2002-01-01

312

Spectroscopy and Photoreactivity of Atmospheric Trace Gases  

Microsoft Academic Search

This thesis explores in detail some aspects of light absorption and light initiated chemical reactions in the atmosphere. The specific themes involved in this work include: laboratory spectroscopic measurements of atmospheric trace gases; fundamental studies of chemical reaction dynamics and the influence of weakly-bound complexes on reactivity; and the atmospheric relevance of the photoreactions of complexes. Laboratory studies of ultraviolet-visible

Gregory John Frost

1995-01-01

313

Thermodesorption of Gases from Various Vacuum Materials.  

National Technical Information Service (NTIS)

A number of materials are commonly used as vacuum system walls. The desorption of gases from these materials may contribute significantly to the internal pressure of an unpumped device or to the gas load which a pump must handle in a dynamic system. This ...

L. C. Beavis

1979-01-01

314

Inerting Aircraft Fuel Systems Using Exhaust Gases.  

National Technical Information Service (NTIS)

Our purpose in this proposal was to determine the feasibility of using carbon dioxide, possibly obtained from aircraft exhaust gases as a substance to inert the fuel contained in fuel tanks aboard aircraft. To do this, we decided to look at the effects ca...

D. G. Hehemann

2002-01-01

315

Method for introduction of gases into microspheres  

Microsoft Academic Search

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,

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

1981-01-01

316

Liquefied petroleum gases. Second edition, revised  

SciTech Connect

An updated, standard reference on the nature, quality, and practical handling of liquefied petroleum gases is presented. New applications such as the role of LPG as a feedstock for chemical production, as well as current safety guidelines and regulations are discussed.

Williams, A.F.; Lom, W.L.

1982-01-01

317

Infrared spectroscopic measurements of tropospheric trace gases  

NASA Astrophysics Data System (ADS)

Absorption features of several trace gases have been detected in 0.017-cm-resolution infrared spectra recorded over surface-level paths of 0.5 and 1.5 km at the National Solar Observatory on Kitt Peak, near Tucson, Arizona. Measurements of O3, HCOOH, NH3, and H2CO are briefly discussed.

Rinsland, Curtis P.; Goldman, Aaron

1992-11-01

318

High Temperature Fabric Filtration of Industrial Gases  

Microsoft Academic Search

The industrial application of fabric filtration of gases was limited for many years by the low thermal resistance of organic filter media; filtration temperatures were restricted to below about 275°F. The introduction of silicone finished glass fabrics just over 10 years ago effectively doubled this limit, and glass fiber material remains today the only commercially available fabric in general use

Paul W. Spaite; David G. Stephan; Andrew H. Rose Jr

1961-01-01

319

Teacher's Guide for Balloons and Gases.  

ERIC Educational Resources Information Center

This guide was developed to provide children with an opportunity to prepare and collect several common gases and to discover and work with some of their properties. The guide is divided into five major sections: (1) introduction, (2) materials, (3) activities, (4) balloons aloft, and (5) an appendix. The introduction provides information…

Griffith, Joe H.; And Others

320

Comparing the emissions of different greenhouse gases.  

National Technical Information Service (NTIS)

The emission of non-CO(sub 2) greenhouse gases should be included in evaluating strategies to reduce greenhouse gas emissions. For developing such strategies a distinction can be made between two extreme approaches: the limitation of the emissions of each...

J. R. Ybema

1990-01-01

321

Ratio of Specific Heats of Gases  

NSDL National Science Digital Library

Students bounce a steel ball in a gas-filled tube. The compressed gas provides a restoring force on the ball. By measuring the distance of initial fall or the frequency of oscillation, the ratio of specific heats of several gases, Cp/Cv may be determined.

2009-02-16

322

Ultracold quantum gases in optical lattices  

Microsoft Academic Search

Artificial crystals of light, consisting of hundreds of thousands of optical microtraps, are routinely created by interfering optical laser beams. These so-called optical lattices act as versatile potential landscapes to trap ultracold quantum gases of bosons and fermions. They form powerful model systems of quantum many-body systems in periodic potentials for probing nonlinear wave dynamics and strongly correlated quantum phases,

Immanuel Bloch

2005-01-01

323

IMG: Interferometric Monitor for Greenhouse Gases.  

National Technical Information Service (NTIS)

The instrumentation for, data processing and analysis of, and expected results of the Interferometric Monitor for Greenhouse Effect Gases (IMG) such as CO2, CH4, N2O, and chlorofluorocarbons (CFC) to be carried onboard the Advanced Earth Observing Satelli...

R. Imasu T. Ogawa H. Shimoda H. Kobayashi

1993-01-01

324

Measurements of Gas Amplification in Noble Gases  

NASA Astrophysics Data System (ADS)

Avalanche multiplication in noble gases with ethane and methane quenchers were measured in the ``gain" region of 10^3 - 10^5. The data provide future chamber designers with useful information concerning the effects of changes in pressure and voltage on the gain as well as absolute gain calculations from knowledge of the First Townsend Coefficient.

Wyatt, Julie

1999-11-01

325

Question of Chemical Transformation of UGC Gases.  

National Technical Information Service (NTIS)

The gaseous product of the underground gasification of coal has considerable shortcomings as a petrochemical feedstock: low content of hydrogen, high content of inert gases (CO sub 2 , N sub 2 ), low methane (1-2 percent), etc. A review of possible method...

A. M. Mosin I. F. Bogdanov I. L. Farberov V. Z. Volkov

1965-01-01

326

Solvable models of classical lattice gases  

Microsoft Academic Search

We study classical lattice gases at fixed temperature but variable fugacity. It is shown how the thermodynamic functions may be calculated exactly provided the Boltzmann weights are representable as principal minors of a convolution operator. We explicitly construct this operator for the cluster models of Fisher and Felderhof.

Gert Roepstorff

1981-01-01

327

Localized electrons in dense heavy noble gases  

Microsoft Academic Search

The paper addresses counterintuitive behavior of electrons injected into dense cryogenic media with negative scattering length a0. Instead of the expected polaronic effect (formation of density enhancement clusters) which should substantially reduce the electron mobility, an opposite picture is observed: with increasing |a0| (the trend taking place for inert gases with the growth of atomic number) and the medium density,

S. Nazin; V. Shikin

2009-01-01

328

Voluntary Reporting of Greenhouse Gases, 2002.  

National Technical Information Service (NTIS)

The Voluntary Reporting of Greenhouse Gases Program, required by Section 1605(b) of the Energy Policy Act of 1992, records the results of voluntary measures to reduce, avoid, or sequester greenhouse gas emissions. A total of 228 U.S. companies and other o...

2004-01-01

329

Simulations of the influence of increasing green house gases on the structure and composition of the stratosphere and mesosphere  

Microsoft Academic Search

It is accepted that tropospheric concentrations of several radiatively active (or green house) gases have been increasing over the latter part of the twentieth century. The extent to which this increase is responsible for changes in the structure and composition of the stratosphere and mesosphere seen in recent satellite and ground based observations has yet to be determined. Using the

D. Marsh; F. Sassi; D. Kinnison; R. Garcia; B. Boville

2002-01-01

330

Radiative Energy Budget in the Cloudy and Hazy Arctic  

Microsoft Academic Search

A radiation model is constructed that includes radiative interactions with atmospheric gases as well as parameterized treatments of scattering and absorption\\/emission by cloud droplets and haze particles. A unified treatment of solar and terrestrial radiation is obtained by using identical cloud and haze parameterization procedure for the shortwave and longwave region. The influence of the relative humidity of the haze

Si-Chee Tsay; Knut Stamnes; Kolf Jayaweera

1989-01-01

331

46 CFR 194.20-17 - Compressed gases.  

Code of Federal Regulations, 2011 CFR

...USE, AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Chemical Stores and/or Storerooms § 194.20-17 Compressed gases...8) cylinders total are stowed simultaneously in the same chemical storeroom. (b) Flammable compressed gases and...

2011-10-01

332

29 CFR 1910.101 - Compressed gases (general requirements).  

Code of Federal Regulations, 2010 CFR

...conducted in accordance with Compressed Gas Association Pamphlets...in § 1910.6. (b) Compressed gases. The in-plant handling, storage, and utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or...

2010-07-01

333

29 CFR 1910.101 - Compressed gases (general requirements).  

Code of Federal Regulations, 2010 CFR

...conducted in accordance with Compressed Gas Association Pamphlets...in § 1910.6. (b) Compressed gases. The in-plant handling, storage, and utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or...

2009-07-01

334

29 CFR 1910.101 - Compressed gases (general requirements).  

Code of Federal Regulations, 2013 CFR

...conducted in accordance with Compressed Gas Association Pamphlets...in § 1910.6. (b) Compressed gases. The in-plant handling, storage, and utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or...

2013-07-01

335

Supercontinuum generation in gases: A high order nonlinear optics phenomenon  

SciTech Connect

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

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

1986-01-01

336

EOSN: A TOUGH2 module for noble gases  

Microsoft Academic Search

We developed a new fluid property module for TOUGH2, called EOSN, to simulate transport of noble gases in the subsurface. Currently, users may select any of five different noble gases as well as CO2, two at a time. For the three gas components (air and two user-specified noble gases) in EOSN, the Henry's coefficients and the diffusivities in the gas

Chao Shan; Karsten Pruess

2003-01-01

337

46 CFR 194.20-17 - Compressed gases.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Compressed gases. 194.20-17 Section 194.20-17 Shipping...or Storerooms § 194.20-17 Compressed gases. (a) Nonflammable compressed gases (excluding oxygen) may be securely stowed...

2012-10-01

338

Method of producing pyrolysis gases from carbon-containing materials  

Microsoft Academic Search

A gasification process of improved efficiency is disclosed. A dual bed reactor system is used in which carbon-containing feedstock materials are first treated in a gasification reactor to form pyrolysis gases. The pyrolysis gases are then directed into a catalytic reactor for the destruction of residual tars\\/oils in the gases. Temperatures are maintained within the catalytic reactor at a level

Lyle K. Mudge; Michael D. Brown; Wayne A. Wilcox; Eddie G. Baker

1989-01-01

339

BIOMASS BURNING AND THE PRODUCTION OF GREENHOUSE GASES  

Microsoft Academic Search

Biomass burning is a source of greenhouse gases, carbon dioxide, methane, and nitrous oxide. In addition, biomass burning is a source of chemically active gases, including carbon monoxide, nonmethane hydrocarbons, and nitric oxide. These gases, along with methane, lead to the chemical production of tropospheric ozone (another greenhouse gas) as well as control the concentration of the hydroxyl radical, which

Joel S. Levine

340

40 CFR 86.514-78 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Analytical gases. 86.514-78 Section 86...NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for 1978 and...Test Procedures § 86.514-78 Analytical gases. (a) Analyzer gases....

2013-07-01

341

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

342

Fickian filtering of cavity gases rising through a fractured permeable overburden  

Microsoft Academic Search

In naturally or explosively fractured geologic media most of the responsibility is associated with the fracture network, whereas most of the porosity resides within the matrix blocks. Thus, both levels of porosity, fracture and matrix, are important in controlling the transient migration of radioactive gases from an underground nuclear cavity to the earth`s surface. A numerical model of a double-porosity

R. H. Nilson; K. Lie; E. W. Peterson

1987-01-01

343

Fickian filtering of cavity gases rising through a fractured permeable overburden  

Microsoft Academic Search

In naturally or explosively fractured geologic media most of the responsibility is associated with the fracture network, whereas most of the porosity resides within the matrix blocks. Thus, both levels of porosity, fracture and matrix, are important in controlling the transient migration of radioactive gases from an underground nuclear cavity to the earth's surface. A numerical model of a double-porosity

R. H. Nilson; K. Lie; E. W. Peterson

1987-01-01

344

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

345

Combustion vs. Pyrolysis of Presolar Diamonds: Association of P3 and HL Noble Gases with Carbon  

Microsoft Academic Search

Since it became clear that presolar diamonds are not identical and perhaps consist of several carriers of isotopically anomalous (like HL-Xe and light nitrogen) and isotopically normal (carbon and P3 noble gases) components, it is important to know how these components are related to the diamond carriers. Because of diamond grains are too small to be analyzed individually and the

A. B. Verchovsky; A. V. Fisenko; C. T. Pillinger

1995-01-01

346

Computer Simulation Studies of Adsorption of Simple Gases on Alkali Metal Surfaces  

Microsoft Academic Search

Wetting properties of simple gases on alkali metal surfaces are of fundamental importance because they manifest the least attractive gas-surface interactions in nature and because their critical behavior is described by the two-dimensional Ising model. We report simulation results for the adsorption of neon and hydrogen on alkali metal surfaces. These use the grand canonical (classical) Monte Carlo and (quantum)

M. J. Bojan; M. W. Cole; J. K. Johnson; W. A. Steele; Q. Wang

1998-01-01

347

Production of ethanol from refinery waste gases. Phase 2, technology development, annual report  

Microsoft Academic Search

Oil refineries discharge large volumes of Hâ, CO, and COâ from cracking, coking, and hydrotreating operations. This program seeks to develop a biological process for converting these waste gases into ethanol, which can be blended with gasoline to reduce emissions. Production of ethanol from all 194 US refineries would save 450 billion BTU annually, would reduce crude oil imports by

D. Arora; R. Basu; J. R. Phillips; C. V. Wikstrom; E. C. Clausen; J. L. Gaddy

1995-01-01

348

Simulating Aerosol-cloud-radiation Feedbacks over East Asia Using Wrf-chem  

NASA Astrophysics Data System (ADS)

Aerosols play an important role in climate change through their impact on the radiative balance of the atmosphere. Recently much effort has been put into studying the radiative forcing of aerosols in East Asia. In this study, we apply the regional chemistry and transport model, WRF-Chem, to study aerosol radiative forcing over eastern Asia. Version 3.3 of the model is used with the CBMZ chemical mechanism and the MOSAIC aerosol treatment. The time period of interest is Feb 21, 2005 to April 12, 2005, since there were extensive measurements of radiation, trace gases, and aerosol properties available from EAST-AIRE (East Asian Study of Tropospheric Aerosols: An International Regional Experiment ) campaign during that period. We conduct model simulations with and without aerosol forcing and compare the results to measurements. We investigate the aerosol radiative forcing as well as aerosol direct and indirect effects by analyzing the differences between short wave flux, temperature, and cloud fraction from these two runs. We evaluate our model simulated incoming short wave radiation at the surface with in situ measurements from EAST-AIRE site Xianghe (70 km southeast of Beijing, China). We find that shortwave radiation decreases when aerosols are added lessening the high-bias between model-calculated and observed short wave radiation. We further compare the model simulated cloud fraction from two runs with MODIS Level 2 retrievals, demonstrating aerosol indirect effects in cloud formations.

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

2011-12-01

349

Itinerant ferromagnetism in ultracold Fermi gases  

SciTech Connect

Itinerant ferromagnetism in cold Fermi gases with repulsive interactions is studied applying the Jastrow-Slater approximation generalized to finite polarization and temperature. For two components at zero temperature, a second-order transition is found at ak{sub F}{approx_equal}0.90 compatible with results of quantum-Monte-Carlo (QMC) calculations. Thermodynamic functions and observables, such as the compressibility and spin susceptibility and the resulting fluctuations in number and spin, are calculated. For trapped gases, the resulting cloud radii and kinetic energies are calculated and compared to recent experiments. Spin-polarized systems are recommended for effective separation of large ferromagnetic domains. Collective modes are predicted and tricritical points are calculated for multicomponent systems.

Heiselberg, H. [Applied Research, DALO, Lautrupbjerg 1-5, DK-2750 Ballerup (Denmark)

2011-05-15

350

Gases released by surface flashover of insulators  

NASA Astrophysics Data System (ADS)

The gases released by surface flashovers on alumina ceramics, Pyrex glass, and quartz, using 20 microsecond voltage pulses were investigated using an ion pumped metal vacuum system. Appreciable quantities of gas were measured (approximately 0.000006 torr-liters or 10 to the 13th molecules). The composition of this gas differed significantly from the background gas. The dominant species in the surface flashover gases were CO2, CO, and H2; a modest amount of CH4 was observed, along with lesser quantities of N2 and H2O. The dominant gas in the system background was nitrogen, accompanied by (in decreasing amounts) H2, H2O, CO/CO2, Ar, CH4, and He. We concluded that the gas released by flashovers on the surface of the insulators was not absorbed system background gas, but gas was adsorbed during the handling and processing of the insulator.

Miller, H. C.; Ney, R. J.

1987-07-01

351

Evaluation of Interruption Capability on Various Gases  

NASA Astrophysics Data System (ADS)

Electrical characteristics of Air, CO2, etc. are studied as candidate of substitute gas for SF6. To evaluate their interruption capability as close as actual case the gas blasting with sonic velocity was applied. Authors have measured time constant (?) and power loss coefficient (N0). In this experiment, Air, He, CO2, and SF6 and gas mixture with SF6 were varied. Among these gases it was found to be ?SF6N0CO2>N0air>N0He, and it is understood that the arc extinction performance of CO2 was excellent except for SF6. Moreover, the time constant became large when the rate of SF6 in mixture gas was reduced, and the power loss coefficient became small. Moreover, the simulation of the SLF interception by EMTP was performed using the obtained arc parameters of the various gases.

Motiduki, Kunio; Ueno, Takafumi; Mizoguchi, Hitoshi; Yanabu, Satoru; Okabe, Sigemitu; Yuasa, Sadayuki

352

Sampling and analysis of gases and vapors  

SciTech Connect

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

Coffman, M.A.; Singh, J.

1991-08-01

353

Quantum fluctuations in dipolar Bose gases  

SciTech Connect

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

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

2011-10-15

354

Analysis of gases in the earth's crust  

NASA Astrophysics Data System (ADS)

One hundred thirty-one natural gas samples were collected for chemical analysis and stable isotopic measurements of carbon, hydrogen, nitrogen, sulfur, and helium. Studies of these and earlier samples have improved geochemical models for hydrocarbon exploration by: (1) augmenting the understanding of the origin and distribution of microbial gases; (2) introducing more effective ways of recognizing mixing between microbial and thermogenic gases; and (3) documenting a novel instance of reservoir alteration by bacteria. Based on the characteristics commonly attributed to deep-earth gas, it was concluded that deep-earth hydrocarbons are a minor component in most oil and gas reservoirs. Deep-earth carbon dioxide and nitrogen could be volumetrically more significant. These conclusions are currently being tested in the supergiant Hugoton-Panhandle gas production area of the U.S. Mid-continent.

Jenden, P. D.

1987-05-01

355

Potentiometric Gas Sensors for Oxidic Gases  

Microsoft Academic Search

Solid electrolyte-based electrochemical devices combined with an auxiliary phase of oxyacid salt have, in this decade, emerged as new attractive sensors to detect oxidic gases of CO2, NO, NO2 and SO2. Various combinations of solid electrolytes and auxiliary phases as well as various new single or multi-component auxiliary phases have been exploited to improve the gas sensing properties and stability

Noboru Yamazoe; Norio Miura

1998-01-01

356

Global Reactive Gases in the MACC project  

NASA Astrophysics Data System (ADS)

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

Schultz, M. G.

2012-04-01

357

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.)

358

Complex Cyclotron Resonance in Dilute Gases  

Microsoft Academic Search

An X-band electron spin resonance spectrometer has been used to analyze the products of an electrodeless discharge in flowing gases at low pressure. During a search for polyatomic free radical fragments, a multiple signal was found near g=2.0000. Three poorly resolved peaks were found for a variety of paraffins and olefins, while methane, ammonia, methylamine, and sulfur dioxide yielded doublets.

R. L. Collins

1961-01-01

359

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

360

Diffusion of Krypton85 in Dense Gases  

Microsoft Academic Search

With two high-pressure quasi-stationary diffusion cells, one depending upon ionization current measurement and the other scintillation detection of radioactive tracer activity, Fick's law diffusivities were determined for the diffusion of tracer amounts of krypton-85 in dense gases of krypton, argon, nitrogen, helium, carbon dioxide, and ethylene for isotherms about room temperature and densities to 15 mole\\/liter. In order to obtain

Leo Durbin; Riki Kobayashi

1962-01-01

361

Electron Energy Degradation in Rare Gases.  

NASA Astrophysics Data System (ADS)

The one dimensional Boltzmann equation was solved for the degradation of high energy electrons in rare gases. An iterative integration method was employed in which the continuous slowing down approximation replaces the energy loss integral in the collision term. The results are compared with those obtained from an exact integration. This work extends an earlier study employing a steady state formulation (K. Kowari Phys. Rev. A 4, 2500(1989)).

Dillon, M.; Kimura, M.

1996-10-01

362

Condensation cleaning of particulate laden gases  

SciTech Connect

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

Devries, E.

1981-08-18

363

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

364

Density functional theory for atomic Fermi gases  

NASA Astrophysics Data System (ADS)

The interplay between interaction and inhomogeneity for electrons in solids generates many interesting phenomena, including insulating and metallic behaviour, magnetism, superconductivity, quantum criticality and more exotic phases. Many of the same phenomena appear in ultracold fermionic atoms in optical lattices, which provide clean, controlled and tunable `quantum simulators' to explore the intriguing physics of fermionic systems. Although density functional theory (DFT) is widely used to calculate material properties, it has not yet been applied to cold atomic gases in optical lattices. Here we present a new density functional for short-range interactions (as opposed to Coulomb interactions of electrons), which renders DFT suitable for atomic Fermi gases. This grants us access to an extensive toolset, previously developed for materials simulations, to calculate the static and dynamic properties of atomic Fermi gases in optical lattices and external potentials. Ultracold atom quantum simulators can in turn be used to explore limitations of DFT functionals, and to further improve hybrid functionals, thus forming a bridge between materials simulations and atomic physics.

Ma, Ping Nang; Pilati, Sebastiano; Troyer, Matthias; Dai, Xi

2012-08-01

365

(Greenhouse gases and national energy options)  

SciTech Connect

Dr. L. D. Hamilton and Mr. G. A. Goldstein attended the 1st Workshop International Energy Agency (IEA), Energy Technology Systems Analysis Programme (ETSAP) Annex IV, Greenhouse Gases and National Energy Options: Technologies and Costs for Reducing Emissions of Greenhouse Gases, Energy Study Center, Netherlands Energy Research Foundation, Petten, The Netherlands, April 9--11, 1990. As global interest in evaluating the impacts of policies for reducing emissions of greenhouse gases at national and international levels increases, the IEA ETSAP group could be in a good position to make a direct contribution. The group, applying the MARKAL energy/environment linear program as its primary modeling tool, was a forum for international collaboration on energy issues for over a decade. The purpose of this trip was to reassert US DOE interest in the activities of ETSAP Annex IV; obtain knowledge as to the current status of various national efforts; demonstrate the PC version of the US energy system the Market Allocation (MARKAL) model, together with the Brookhaven developed MARKAL Users Support System (MUSS), as a tool to improve greatly MARKAL usability for upcoming analysis and by non-IEA countries, especially developing countries; and participate in establishing a Work Plan for Annex IV.

Hamilton, L.D.

1990-04-18

366

Experimental studies concerning the drying of voloxidizer off-gases  

SciTech Connect

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

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

1981-07-01

367

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

SciTech Connect

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

Levin, Kathryn (University of Chicago)

2007-01-10

368

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

ScienceCinema

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

369

Why "Radiation Oncology"  

PubMed Central

Radiotherapy continues to be a major treatment for solid tumours and is a cornerstone of modern oncology. The term 'radiation oncology' describes the integration of radiation therapy into the complexity of multi-modal therapy. Over the last ten years the crucial role of radiation therapy as part of multi-modality protocols in cancer care has been documented in numerous Phase III trials. Advances in treatment technology as well as the underlying biology of tumour resistance mechanisms will further strengthen the role of radiation oncology. The scientific role of radiation oncology is reflected by the increase in the number of papers related to radiation oncology in resources like Medline. In order to reflect the growing scientific importance of radiation oncology, radiation physics and radiation biology, we have initiated Radiation Oncology as the first open access journal in the field. Open access allows for a rapid and transparent publication process together with an unequalled opportunity to reach the widest reader spectrum possible.

Belka, Claus; Camphausen, Kevin A

2006-01-01

370

Radiative shell thinning in intense laser-driven blast waves  

NASA Astrophysics Data System (ADS)

The structural evolution of blast waves launched by intense laser pulses in gases is investigated. These blast waves exhibit significant energy loss through radiation while propagating in xenon as evidenced by interferometric imaging revealing radiative precursors and deceleration parameters well below those of an energy-conserving wave. Thinning of the blast wave shell from radiative cooling is observed through comparison of shocks launched in gases of differing atomic number. Shell thinning is also measured when the gas density is altered, indicating the influence of conditions within the preshock medium. These results are compared with radiative-hydrodynamic simulations. British Crown Copyright 2009/MOD.

Osterhoff, J.; Symes, D. R.; Edens, A. D.; Moore, A. S.; Hellewell, E.; Ditmire, T.

2009-02-01

371

Seeded optical breakdown of molecular and noble gases  

SciTech Connect

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. [College of Optical Sciences, University of Arizona 1630 E. University Blvd., Tucson, Arizona 85721 (United States)

2012-07-30

372

Investigation of the evolution of modulated radiative blast waves created by high intensity laser - cluster interaction  

NASA Astrophysics Data System (ADS)

Radiative blast waves exhibiting instabilities are common and play an important role in astrophysics. Certain aspects of these astrophysical waves can be reproduced in suitably designed laboratory experiments. Previous laboratory experiments have shown that blast waves can be created from intense laser-cluster interactions and the evolution of these waves in high Z cluster gases is radiative, with trajectories that deviate from an adiabatic Sedov-Taylor expansion. With this approach, we have been studying the evolution of hydrodynamic perturbations on cylindrical blast waves in the radiative regime. In our experiment, cylindrical blast waves are generated by high intensity irradiation of an argon cluster jet. The blast waves' spatial profile is modified by initially destroying clusters in specific locations using another laser pulse. This modulation then becomes the seed to study the variation in the perturbations' amplitude. We observe some initial evidence for the oscillatory behavior predicted by the Vishniac model of perturbations on thin shell blast waves.

Quevedo, H. J.; Kim, I. T.; Bang, W.; Symes, D. R.; Osterhoff, J.; Faustlin, R.; Maurer, M.; Bernstein, A. C.; Moore, A. S.; Gumbrell, E. T.; Edens, A. D.; Smith, R. A.; Ditmire, T.

2008-04-01

373

Energy Relaxation of Helium Atoms in Astrophysical Gases  

NASA Astrophysics Data System (ADS)

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.; Zhang, P.

2012-09-01

374

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

375

Hydrological sensitivity to greenhouse gases and aerosols in a global climate model  

NASA Astrophysics Data System (ADS)

Changes in greenhouse gases and aerosols alter the atmospheric energy budget on different time scales and at different levels in the atmosphere. We study the relationship between global mean precipitation changes, radiative forcing, and surface temperature change since preindustrial times caused by several climate change components (CO2, CH4, sulphate and black carbon (BC) aerosols, and solar forcing) using the National Center for Atmospheric Research Community Earth System Model (CESM1.03). We find a fast response in precipitation due to atmospheric instability that correlates with radiative forcing associated with atmospheric absorption and a slower response caused by changes in surface temperature which correlates with radiative forcing at the top of the atmosphere. In general, global climate models show large differences in climate response to global warming, but here we find a strong relationship between global mean radiative forcing and global mean precipitation changes that is very consistent with other models, indicating that precipitation changes from a particular forcing mechanism are more robust than previously expected. In addition, we look at the precipitation response and relate it to changes in lifetime of atmospheric water vapor (?). BC aerosols have a significantly larger impact on changes in ? related to surface temperature compared to greenhouse gases, sulphate aerosols, and solar forcing and are the dominating forcing mechanism affecting fast precipitation in this quantity.

KvalevâG, Maria Malene; Samset, BjøRn H.; Myhre, Gunnar

2013-04-01

376

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, D.F.

1986-07-01

377

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

378

Sensors for Toxic Gas Detection PLATINUM METALS PERFORM AN IMPORTANT ROLE  

Microsoft Academic Search

The utilisatwn of advanced sensing techniques for detecting, indicating and mon- itoring toxic gases in industry and the environment is very important for health and safety. In this paper, the application of electrochemical, semiconductor, catalyticFeld efSect and catalytic gas sensors for the detection of toxic gases, and the role of platinum group metals in these deoices, is discussed. It is

Yuan-Jin Lei

379

A Knowledge-based Decision Support System For Gases Allocation Planning  

Microsoft Academic Search

The gases energy system in an integrated iron and steel works comprises three main part. gases genera­ ting facilities. gases consuming facilities and gases management unit. The generating facilities are blast furnace . coke oven and converter. The gases are natm-al gas. BE' gas. LD gaS and many kind of mixture gases (with 'different pressure and different hot value). Almost

Cheng Runwel; Wang Dingwei; Li Baoze; Yang Zihou

1988-01-01

380

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

381

Transverse spin diffusion in strongly interacting Fermi gases  

NASA Astrophysics Data System (ADS)

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

Enss, Tilman

2013-09-01

382

Differential optical absorption spectrometer for measuring atmospheric trace gases  

NASA Astrophysics Data System (ADS)

The construction of a differential optical absorption spectrometer (DOAS) is described. The instrument was designed for making automated measurements, with relatively high detection sensitivities, of important tropospheric trace gases, and with the ability to operate in rugged environments without frequent attention. Major innovative features of the instrument include a retroreflector to fold the light path, a diode array detector, and computer-controlled operation of the entire instrument package. The advantages of these modifications with respect to previously reported designs are discussed in detail. This DOAS has been employed since 1989 to measure NO3 (1 ppt), NO2 (0.6 ppb), HONO, O3, and CH2O (0.8 ppb), where the mixing ratios in parentheses indicate the detection limits over a 5 km path length and 4 min integration time, for the species where these could be determined.

Plane, John M. C.; Nien, Chia-Fu

1992-03-01

383

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

384

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

385

Mean free path in soccer and gases  

NASA Astrophysics Data System (ADS)

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

Luzuriaga, J.

2010-09-01

386

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

387

Radiative scaling of the nocturnal boundary layer and the diurnal temperature range  

NASA Astrophysics Data System (ADS)

A radiative scaling for the warm season nocturnal boundary layer (NBL) is proposed, based on the daily mean surface net longwave radiation flux. Using this scaling, a conceptual model is proposed for the NBL, with parameters estimated from multiple linear regression of model data from the European Centre reanalysis, averaged over river basins from the tropics to high latitudes. A radiative temperature scale, computed from surface net longwave radiation flux and the slope of the Stefan-Boltzmann law, primarily determines the strength of the NBL and the amplitude of the diurnal temperature range, although the length of the nighttime period and the surface wind stress play important subsidiary roles. A related radiative velocity scale or radiative conductance, the duration of the nighttime period and the ratio of the scaled surface heat flux (which increases with wind stress) to the NBL strength determine the depth of the NBL. From an observational perspective, this suggests that the diurnal temperature range may give a useful estimate of surface net longwave radiation flux. From a modeling perspective, this provides a framework for relating model physical parameterizations, especially the coupling at night between the surface, the ground and the atmosphere, to observables, the diurnal temperature range and the strength and depth of the NBL. The model is then applied to estimate the nocturnal rise in concentration of gases such as CO2 and radon that are emitted at the surface.

Betts, Alan K.

2006-04-01

388

Interlayer trapping of noble gases in insoluble organic matter of primitive meteorites  

NASA Astrophysics Data System (ADS)

Noble gases in primitive meteorites are trapped in a residue left after demineralization of bulk meteorite by HF and HCl. Most of the primordial Ar, Kr and Xe and small amounts of He and Ne are removed by oxidation of this acid-resistant residue, e.g. with HNO3. These gases, referred as P1, are trapped in a poorly characterized, presumably organic, phase labeled phase Q. In order to understand the siting of P1 noble gases, we have performed a solvation experiment on insoluble organic matter of Orgueil (CI). Pyridine was used because it presents an important swelling ratio of about 2 potentially able to change considerably the structure of phase Q without affecting the crystalline structure of nanodiamonds, chromite, spinel and metal alloys present in acid residue. Heavy noble gases are largely lost upon pyridine treatment at room temperature. However, the elemental pattern of the remaining Ar, Kr and Xe is not different from that of the starting acid residue, showing similar losses of all the heavy noble gases during solvation. Xenon stepwise heating data and deconvolution of different components based on isotopic ratios show that Xe-P1 is mainly affected by loss (? 60%), following by Xe-P3 (? 25%) and Xe-HL (? 12%). The xenon release is maximum at temperatures ? 1300 °C (? 70 80%) whereas only 23% is lost at 1600 °C and no further loss occurs at 2100 °C. These results suggest the existence of at least two substructures in phase Q, with Xe-P1 being trapped preferentially in the less retentive phase. As macromolecular organic matter is the only phase of acid residue sensitive to solvation, this study demonstrates the organic nature of phase Q. The behavior of heavy noble gases upon pyridine solvation supports interlayer trapping of these elements, probably within organic layers of aromatic moieties linked by short aliphatic chains.

Marrocchi, Yves; Derenne, Sylvie; Marty, Bernard; Robert, François

2005-08-01

389

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

SciTech Connect

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

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

1993-01-01

390

Acute radiation syndrome caused by accidental radiation exposure - therapeutic principles  

PubMed Central

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

2011-01-01

391

Process for removal of carbonyl sulfide in liquified hydrocarbon gases with absorption of acid gases  

Microsoft Academic Search

Liquified hydrocarbon gases containing at least carbonyl sulfide as an impurity are purified by intimately mixing the liquified hydrocarbon gas with an aqueous absorbent for hydrogen sulfide in a hydrolysis zone maintained at a temperature and a pressure sufficient to maintain the liquified hydrocarbon gas in the liquid state and hydrolyze the carbonyl sulfide to hydrogen sulfide and carbon dioxide.

D. K. Beavon; M. Mackles

1980-01-01

392

Hydrodynamics and universality in cold atomic gases  

NASA Astrophysics Data System (ADS)

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

Abanov, Alexander; Kulkarni, Manas

2013-03-01

393

Gases released by surface flashover of insulators  

SciTech Connect

The gases released by surface flashovers on alumina ceramics, Pyrex glass, and quartz, using 20-..mu..s voltage pulses were investigated using an ion pumped metal vacuum system. Appreciable quantities of gas were measured (approximately 10/sup -6/ torr-liters or 10/sup 13/ molecules). The composition of this gas differed significantly from the background gas. The dominant species in the surface flashover gases were CO/sub 2/, CO, and H/sub 2/; a modest amount of CH/sub 4/ was observed, along with lesser quantities of N/sub 2/ and H/sub 2/O. The dominant gas in the system background was nitrogen, accompanied by (in decreasing amounts) H/sub 2/, H/sub 2/O, CO/CO/sub 2/, Ar, CH/sub 4/, and He. We concluded that the gas released by flashovers on the surface of the insulators was not absorbed system background gas, but was gas adsorbed during the handling and processing of the insulator.

Miller, H.C.; Ney, R.J.

1987-07-20

394

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.

395

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

396

Radiation disasters and children.  

PubMed

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

2003-06-01

397

Patterns of Trace Gases Near Sources of Global Pollution  

Microsoft Academic Search

Many trace gases are increasing in the earth's armosphere and may couase global environmental changes in the future. Consequently there has been growing interest in the cycles of the long-lived gases that are likely to contribute the most to global change. At present there are four such gases: methane (CHâ), nitrous oxide (Nââ, trichlorofluoromethane (CClâF,F-11), and dichlorodifluoromethane (CClâFâ,F-12). Methane and

M. A. K. Khalil; R. A. Rasmussen

1990-01-01

398

Dynamics of plasma gratings in atomic and molecular gases  

NASA Astrophysics Data System (ADS)

The decay of the plasma grating formed at the intersection of two femtosecond filaments is measured in several molecular and atomic gases. The grating evolution is ruled by ambipolar diffusion in atomic gases and by a combination of ambipolar diffusion and collision-assisted free electron recombination in molecular gases. Electron diffusion and recombination coefficients are extracted for Ne, Ar, Kr, Xe, N2, O2, CO2, and air at 1 bar.

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

2012-09-01

399

Method for controlling corrosion in thermal vapor injection gases  

DOEpatents

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

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

1981-01-01

400

Radiation Damage Effects  

NASA Astrophysics Data System (ADS)

Radiation damage is an important issue for the particle detectors operated in a hostile environment where radiations from various sources are expected. This is particularly important for high energy physics detectors designed for the energy and intensity frontiers. This chapter describes the radiation damage effects in scintillating crystals, including the scintillation-mechanism damage, the radiation-induced phosphorescence, and the radiation-induced absorption. The radiation damage mechanism in crystal scintillators is also discussed. While the damage in halides is attributed to the oxygen/hydroxyl contamination, it is the structure defects, such as the oxygen vacancies, which cause the damage in oxides. Various material analysis methods used in investigations of the radiation damage effects as well as the improvement of crystal quality through systematic R&D are also presented.

Zhu, R.-Y.

401

Analysis of gases in Mississippi Valley-type ore fluids  

SciTech Connect

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 CO/sub 2/, N/sub 2/, and CH/sub 4/. The hydrocarbon content of the fluids is low (<0.1 mole%) and consists largely of CH/sub 4/ with traces of C/sub 2/H/sub 6/. Because the amount of CH/sub 4/ present is low, post trapping production of CH/sub 4/ from organic matter within the inclusions could not have significantly affected the filling temperatures reported for these deposits. High CO/sub 2/ contents of up to 2 mole % have been measured by mass spectrometry in sphalerite from northern Arkansas. Comparable CO/sub 2/ contents were obtained by both thermal decrepitation and room temperature crushing. Thermal gas evolution profiles show that peak CO/sub 2/ release occurs at a higher temperature than for H/sub 2/O release. These observations suggest the presence of CO/sub 2/-rich inclusions. Although CO/sub 2/-rich inclusions have not been observed optically, they may reside among the many, small, dark, inclusions with strong internal reflections commonly seen in sphalerite. The CO/sub 2/-rich inclusions could represent periods of CO/sub 2/ effervescence during host rock dissolution and sulfide deposition. The thermal maturity and low concentration of hydrocarbons, together with the high CO/sub 2/ content,suggest that these ore-forming fluids are highly evolved basinal brines.

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

1985-01-01

402

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

403

Veracruz State Preliminary Greenhouse Gases Emissions Inventory  

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

404

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.

405

Future UV radiation in Central Europe modelled from ozone scenarios  

Microsoft Academic Search

Photobiologically and photochemically relevant UV radiation for the time around the years 2015 and 2050 is estimated by radiative transfer calculations using variable ozone content based on model simulations. The future cloud conditions are assumed unchanged. Assuming various emission scenarios of chlorfluorohydrocarbons (CFCs) and other trace gases, and taking into account future temperature development and changing atmospheric dynamic conditions, ozone

Joachim Reuder; Martin Dameris; Peter Koepke

2001-01-01

406

Two-dimensional high speed flow of a radiating gas  

Microsoft Academic Search

In high speed gas dynamics the analysis of two-dimensional flows of hot gases, where the effect of radiation as a mode of energy transfer cannot be neglected, is extremely difficult due to the integro-differential nature of the governing equations. To date, most of the existing literature on radiation gas dynamics is confined to the study of the two asymptotic cases

Prem K. Khosla

1968-01-01

407

The History of Planetary Degassing as Recorded by Noble Gases  

NASA Astrophysics Data System (ADS)

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

Porcelli, D.; Turekian, K. K.

2003-12-01

408

Small-scale experimental testing of fire radiative energy for quantifying mass combusted in natural vegetation fires  

NASA Astrophysics Data System (ADS)

Combustion of forest and grassland vegetation contributes to atmospheric pollution and rising greenhouse gases concentrations. Remotely measuring the energy radiated during natural fires has been suggested as a method for enhancing current emissions estimates. When made from satellites, such measures can potentially provide important new information on large-scale biomass combustion rates, which relate directly to the production of emissions. EOS-MODIS now makes such observations globally, multiple times per day. Using small experimental fires observed with a field spectro-radiometer we present the first evaluation of the relationship between time-integrated fire radiative energy and total mass of vegetation combusted. Results indicate a linear relationship (r2 = 0.78) for fire sizes varying over almost two orders of magnitude. Further information on the rate and intensity of burning is contained within the emission spectra. The results support the continued investigation of fire radiative energy as a new tool to enhance biomass burning emissions inventories.

Wooster, Martin J.

2002-11-01

409

Free electron in compressed inert gases  

SciTech Connect

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

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

2008-08-15

410

Sir William Ramsay and the noble gases.  

PubMed

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

Davies, Alwyn G

2012-01-01

411

Multiply-Substituted Isotopologues of Atmospheric Gases  

NASA Astrophysics Data System (ADS)

Stable isotope geochemistry is principally concerned with bulk isotopic compositions of natural materials (e.g., d13C). In atmospheric gases, these bulk compositions effectively depend only on abundances of molecules containing one rare isotope (e.g., 16O13C16O). However, the common di- and tri-atomic atmospheric gases also contain ca. 10-5 to 10-6 mole fraction of molecules containing two or more rare isotopes (e.g., 18O13C16O). These rare isotopologues are an untapped resource of constraints on physical chemistry and geochemical budgets. There are sparse data on the vapor pressures and chemical kinetics of multiply-substituted isotopologues, and the reduced partition functions of some were estimated by Urey (1947) and Bigeleisen and Mayer (1947). These studies demonstrate that these rare isotopologues have unique thermodynamic and kinetic properties, and thus that routine measurements of them could uniquely constrain geochemical problems. However, distributions of these rare isotopologues in nature are essentially unknown. We have developed a gas source mass spectrometer for analysis of doubly substituted isotopologues of N2, NO, CO, O2, CO2 and N2O at their naturally occurring abundances (in addition to the common and singly substituted isotopologues of these gases); associated sample preparation techniques and standardization protocols have been developed for CO2, N2O and are in progress for O2. Capabilities of this instrument vary with the abundances of the isotopologue of interest; external precision for the most abundant (e.g., 18O13C16O; 40 ppm of natural CO2) is typically ~0.03 per mil, 1s, whereas that for more rare species (e.g., 18O12C18O; ca. 4 ppm of respective molecules) is typically ~0.1 to 0.2 per mil, 1s. Accuracy based on comparisons to standards having the stochastic distribution of isotopes is similar to external precision. Interferences are the greatest analytical difficulty, with hydrocarbon fragments and recombination products being the most common and recalcitrant problem. The most extensive use of this instrument to-date has been to measure abundances of 18O13C16O in air and in experimental products. Preliminary results for 18O13C18O, 15N14N18O and 14N15N18O will also be reviewed, as will expected data for 18O18O and 17O18O if sufficiently complete. Near-surface air in southern California in mid-2003 is characterized by a 0.72 per mil enrichment in 18O13C16O relative to the abundance predicted for a stochastic (random) distribution of 18O and 13C among all CO2 isotopologues. This enrichment can be attributed to enhanced thermodynamic stability of 18O13C16O during air-sea and air-leaf water exchange - which generates ca. 0.9 per mil enrichments - modulated by anthropogenic emissions, fires and diffusive fractionations during photosynthesis - all of which slightly (less than 0.1 per mil) reduce 18O13C16O mixing ratios. Variations in 18O13C16O in air with time and location will constrain the mean temperature of air-sea and air-leaf water exchange (and thereby add to the interpretation of d18O of CO2), and contributions from anthropogenic emissions and biomass burning. We will present data comparing southern California and Alaska during summer, 2003 as examples of these effects. Photolysis experiments on N2O demonstrate that photochemical reactions can generate large (up to tens of per mil) enrichments in multiply substituted isotopologues relative to their predicted stochastic abundance. Potential uses of such effects to constrain the physical budgets and physical chemistry of atmospheric gases will be discussed.

Eiler, J. M.; Schauble, E.; Wang, Z.

2003-12-01

412

Mixtures of degenerate Fermi and Bose gases  

NASA Astrophysics Data System (ADS)

We report on experiments with ultra-cold mixtures of fermonic and bosonic lithium gases. 6Li and 7Li are cooled by standard laser cooling techniques and transferred into a Ioffe-Pritchard magnetic trap. Evaporative cooling is performed selectively on the bosonic isotope (7Li), while its fermionic counterpart (6Li) is cooled sympathetically until quantum degeneracy is reached. A 6Li Fermi sea at a temperature of 1/5 of the Fermi temperature, mixed with a 7Li Bose-Einstein condensate is produced. Optical trapping of a Fermi gas with two spin components is described. Finally, by using a Feshbach resonance in 7Li to tune the atomic interaction in the gas, matter wave bright solitons are produced in an optical waveguide. Propagation without spreading over a distance of more than 1 mm is observed.

Khaykovich, L.; Cubizolles, J.; Bourdel, T.; Schreck, F.; Ferrari, G.; Carr, L.; Castin, Y.; Salomon, C.

2003-04-01

413

Adsorption of Atmospheric Gases on Pu Surfaces  

SciTech Connect

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

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

2012-03-29

414

Strongly Interacting Two-Dimensional Bose Gases  

NASA Astrophysics Data System (ADS)

We prepare and study strongly interacting two-dimensional Bose gases in the superfluid, the classical Berezinskii-Kosterlitz-Thouless (BKT) transition, and the vacuum-to-superfluid quantum critical regimes. A wide range of the two-body interaction strength 0.05

Ha, Li-Chung; Hung, Chen-Lung; Zhang, Xibo; Eismann, Ulrich; Tung, Shih-Kuang; Chin, Cheng

2013-04-01

415

Concomitant modulated superfluidity in polarized Fermi gases  

SciTech Connect

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

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

2011-02-15

416

Upper ocean model of dissolved atmospheric gases  

SciTech Connect

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

Schudlich, R.; Emerson, S.

1992-01-01

417

Voluntary reporting of greenhouse gases 1997  

SciTech Connect

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

NONE

1999-05-01

418

Clustering and phases of compartmentalized granular gases  

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

419

Clustering and phases of compartmentalized granular gases.  

PubMed

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

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

2009-02-27

420

Ripples and dots generated by lattice gases  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

421

Critical UN Conference on Greenhouse Gases Begins  

NSDL National Science Digital Library

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

Charbonneau, David D.

422

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

423

Light hydrocarbon gases in Guaymas basin hydrothermal fluids: Thermogenic versus abiogenic origin  

SciTech Connect

Light hydrocarbon gases (methane through pentane) in high-temperature hydrothermal fluids of the Guaymas basin, Gulf of California, are predominantly derived from thermocatalysis of organic carbon in sediments intruded by mid-ocean ridge volcanic rocks. The spectrum of C{sub 1}-C{sub 5} gases in Guaymas basin hydrothermal fluids is characterized by a preponderance of alkanes, with essentially no alkenes present. Comparison with high-temperature fluids from 21{degree}N on the East Pacific Rise, where geochemical evidence indicates a distinct lack of thermogenic gas and where methane is derived abiogenically from the basalts, shows that the 21{degree}N hydrocarbon gases are characterized by a prominent ethylene signature. Stable isotope compositions of Guaymas basin methane differ from 21{degree}N gas; Guaymas basin has {delta}{sup 13}C values of {minus}43 to {minus}51 {per thousand} vs. PDB, compared to 21{degree}N where values as high as {minus}15 {per thousand} have been measured. These differences reflect the different origins of light hydrocarbon gases in the two systems, with Guaymas methane being overwhelmingly of an organic, thermogenic derivation and showing no evidence of the abiogenic, basalt-derived gas that characterizes the 21{degree}N environment. Carbon isotope analyses of dissolved inorganic carbon in Guaymas basin hydrothermal fluids indicate that high-temperature hydrocarbon oxidation may be an important process acting in conjunction with high-temperature thermocatalytic hydrocarbon generation. 4 figs., 6 tabs.

Welhan, J.A.; Lupton, J.E. (Scripps Institution of Oceanography, La Jolla, CA (USA))

1987-02-01

424

Radiative flux measurements in the troposphere  

Microsoft Academic Search

The results of radiative flux-density measurements in the troposphere, made using an especially designed radiometer mounted on a Cessna 402B aircraft, are reported. The radiometer incorporates several well-known principles that result in highly accurate determinations of radiative fluxes in the atmosphere. Heating rates for gases and for aerosols are calculated, using measurements and radiosonde data. Instrument performance is verified by

Francisco P. J. Valero; Warren J. Y. Gore; Lawrence P. M. Giver

1982-01-01

425

An excimer emitter with pumping by barrier discharge in mixtures of zink diiodide vapors with inert gases  

Microsoft Academic Search

An experimental investigation is performed of the output characteristics of an excimer lamp utilizing mixtures of zinc diiodide\\u000a vapors with inert gases and excited by a barrier discharge (BD) with the repetition rate of sine voltage pulses f ? 130 kHz. Radiation spectra of BD plasma in the range of 200–900 nm with resolution of 0.05 nm are studied, as

N. N. Guivan; A. N. Malinin

2006-01-01

426

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

USGS Publications Warehouse

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

Larson, D. L.

1994-01-01

427

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

428

Using Biogenic Sulfur Gases as Remotely Detectable Biosignatures on Anoxic Planets  

PubMed Central

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

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

2011-01-01

429

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

430

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

PubMed

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

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

2011-06-10

431

Laboratory Studies of Homogeneous and Heterogeneous Chemical Processes of Importance in the Upper Atmosphere.  

National Technical Information Service (NTIS)

The objective of this study was to conduct measurements of chemical kinetics parameters for reactions of importance in the stratosphere and upper troposphere, and to study the interaction of trace gases with ice surfaces in order to elucidate the mechanis...

M. J. Molina

2003-01-01

432

Molecular structure and radiative efficiency of fluorinated ethers: A structure-activity relationship  

NASA Astrophysics Data System (ADS)

Fluorinated ethers are receiving attention as possible replacements for ozone-depleting substances. Accurate knowledge of their radiative forcing is required to assess the contribution of these compounds to climate change. Radiative efficiency is a metric used to determine the potential of long-lived greenhouse gases to impact climate. A structure-activity relationship (SAR) was derived that can estimate the majority of radiative efficiencies of fluorinated ether compounds within 25% of the published experimentally determined values. The SAR allows prediction of radiative efficiency solely from molecular structure and was developed from 154 calculated and 11 experimentally measured infrared spectra for fluorinated ethers. Stretching vibrations for C-F bonds adjacent to an ether oxygen absorb at lower frequencies than those which are further removed from the ether moiety, which typically gives rise to a higher radiative efficiency. Molecular structure plays an important role in determining the radiative efficiency of fluorinated ethers. The SAR developed herein could be used in the design of new fluorinated ethers that have minimal climate impacts.

Young, Cora J.; Hurley, Michael D.; Wallington, Timothy J.; Mabury, Scott A.

2008-12-01

433

The effect of aerosol on surface cloud radiative forcing in the Arctic  

NASA Astrophysics Data System (ADS)

Cloud radiative forcing is a very important concept to understand what kind of role the clouds play in climate change with thermal effect or albedo effect. In spite of that much progress has been achieved, the clouds are still poorly described in the climate models. Due to the complex aerosol-cloud-radiation interactions, high surface albedo of snow and ice cover, and without solar radiation in long period of the year, the Arctic strong warming caused by increasing greenhouse gases (as most GCMs suggested) has not been verified by the observations. In this study, we were dedicated to quantify the aerosol effect on the Arctic cloud radiative forcing by Northern Aerosol Regional Climate Model (NARCM). Major aerosol species such as Arctic haze sulphate, black carbon, sea salt, organics and dust have been included during our simulations. By inter-comparisons with the Atmospheric Radiation Measurement (ARM) data, we find surface cloud radiative forcing (SCRF) is -22 W/m2 for shortwave and 36 W/m2 for longwave. Total cloud forcing is 14 W/m2 with minimum of -35 W/m2 in early July. If aerosols are taken into account, the SCRF has been increased during winter while negative SCRF has been enhanced during summer. Our estimate of aerosol forcing is about -6 W/m2 in the Arctic.

Hu, R.-M.; Blanchet, J.-P.; Girard, E.

2005-09-01

434

The Origin of Some Natural Carbon Dioxide Gases  

Microsoft Academic Search

Natural carbon dioxide gas issues from vents and springs in sedimentary rocks. Exploratory wells drilled for oil have produced large volumes of carbon dioxide in subsurface. Where these gases are found in quantity, limestones and igneous rocks are in close association and the origin of the gases is thus suggested. Until the advent of the mass spectrometer there was no

Walter B. Lang

1959-01-01

435

Continuous cryopump with a method for removal of solidified gases  

DOEpatents

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

Carlson, L.W.; Herman, H.

1988-05-05

436

Continuous cryopump with a method for removal of solidified gases  

DOEpatents

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

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

1989-01-01

437

ANALYSIS OF COMMERCIAL NO PROTOCOL GASES (A QA ASSESSMENT)  

EPA Science Inventory

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

438

Origin of production gases from convergent plate margins  

SciTech Connect

Molecular and isotopic composition of hydrocarbon production gases from four convergent plate margins have been measured. New Zealand is represented by two gases from the Taranaki basin in the back arc of the active Tonga-Kermadec subduction system. Gases from Barbados and Taiwan are from forearc locations in the active Lesser Antilles system and relict northern Manila Trench system. Philippine gases from offshore Palawan are associated with the Palawan Trough. Gases from Taiwan, the Maiu field in New Zealand, and the Nido field in Palawan have very high /sup 3/He//sup 4/He ratios, indicating considerable mantle input of helium to the gas reservoirs. Variations in /sup 3/He//sup 4/He ratios in neighboring fields are quite striking and suggest localized sources for the mantle components. Possible sources include shallow igneous bodies and fractures or faults tapping a direct mantle source. Measurements of helium isotope ratios in hydrocarbon production gases have been compiled and show a striking association of mantle helium with gases from subduction zones in contrast to deep subsided or rifted sedimentary basins. The dynamics of the subduction process, involving the interaction of upper mantle and crustal rocks, is apparently responsible for the injection of volatile mantle components into reservoired gases. Current exploration techniques are based on maturation and gas migration theories developed from the study of subsiding sedimentary basins. At convergent margins, such technique may have to be amended to include the effects of subduction dynamics on the source, maturation, and migration of hydrocarbons.

Jeffrey, A.W.A.; Poreda, R.J.; Gwilliam, W.J.; Kaplan, I.R.; Craig, H.

1987-05-01

439

Continuous cryopump with a method for removal of solidified gases  

SciTech Connect

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

Carlson, L.W.; Herman, H.

1989-06-13

440

Sorption and desorption of radioactive noble gases in polycarbonates  

Microsoft Academic Search

The remarkable ability of some polycarbonates to absorb noble gases makes them an useful tool for measurements of radioactive noble gases. In this paper the kinetic of sorption and desorption processes is theoretically and experimentally studied. A theoretical model is proposed that considers diffusion and radioactive decay. Experimental results for 85Kr, 133Xe and 222Rn are presented. They include experimental determination

D. Pressyanov; K. Mitev; S. Georgiev; I. Dimitrova

2009-01-01

441

Performance Demonstration Program Plan for Analysis of Simulated Headspace Gases  

Microsoft Academic Search

The Performance Demonstration Program (PDP) for headspace gases distributes sample gases of volatile organic compounds (VOCs) for analysis. Participating measurement facilities (i.e., fixed laboratories, mobile analysis systems, and on-line analytical systems) are located across the United States. Each sample distribution is termed a PDP cycle. These evaluation cycles provide an objective measure of the reliability of measurements performed for transuranic

2006-01-01

442

A Simple Experiment to Demonstrate the Effects of Greenhouse Gases  

ERIC Educational Resources Information Center

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

Keating, C. F.

2007-01-01

443

STUDYING FLAME DILUTION BY BURNT GASES USING NUMERICAL COMBUSTION  

Microsoft Academic Search

Laminar unstrained and freely propagating premixed oxy-flames diluted by burnt gases are simulated with detailed chemistry. The temperature of the burnt gases is varied with the level of dilution. The response of global flame properties, as flame speed and flame thick- ness, is reported along with the behavior of major species. In a second part, Direct Numerical Simulation of partially

S. Payet; A. Naudin; P. Domingo; B. Labegorre; L. Vervisch

2006-01-01

444

Assessment report on NRP subtheme “gGeenhouse Gases  

Microsoft Academic Search

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

J. G. de Beer

1995-01-01

445

New solvent purifies crude (and) coal acid gases  

Microsoft Academic Search

Allied Chemical Corp. has developed a new solvent process using the dimethyl ether of polyethylene glycol (called Selexol) for the selective absorption of sulfur gases and the bulk removal of acid gases in gasification plants fed with heavy crude oil or coal. The solvent has very different absorption characteristics for carbonyl sulfide, hydrogen sulfide, carbon dioxide, ammonia, and hydrocarbons. Commercial

Valentine

1974-01-01

446

Chemical production from industrial by-product gases: Final report  

Microsoft Academic Search

The potential for conservation of natural gas is studied and the technical and economic feasibility and the implementation of ventures to produce such chemicals using carbon monoxide and h