Sample records for air gas concentration

  1. Air concentrations of volatile compounds near oil and gas production: a community-based exploratory study.

    PubMed

    Macey, Gregg P; Breech, Ruth; Chernaik, Mark; Cox, Caroline; Larson, Denny; Thomas, Deb; Carpenter, David O

    2014-10-30

    Horizontal drilling, hydraulic fracturing, and other drilling and well stimulation technologies are now used widely in the United States and increasingly in other countries. They enable increases in oil and gas production, but there has been inadequate attention to human health impacts. Air quality near oil and gas operations is an underexplored human health concern for five reasons: (1) prior focus on threats to water quality; (2) an evolving understanding of contributions of certain oil and gas production processes to air quality; (3) limited state air quality monitoring networks; (4) significant variability in air emissions and concentrations; and (5) air quality research that misses impacts important to residents. Preliminary research suggests that volatile compounds, including hazardous air pollutants, are of potential concern. This study differs from prior research in its use of a community-based process to identify sampling locations. Through this approach, we determine concentrations of volatile compounds in air near operations that reflect community concerns and point to the need for more fine-grained and frequent monitoring at points along the production life cycle. Grab and passive air samples were collected by trained volunteers at locations identified through systematic observation of industrial operations and air impacts over the course of resident daily routines. A total of 75 volatile organics were measured using EPA Method TO-15 or TO-3 by gas chromatography/mass spectrometry. Formaldehyde levels were determined using UMEx 100 Passive Samplers. Levels of eight volatile chemicals exceeded federal guidelines under several operational circumstances. Benzene, formaldehyde, and hydrogen sulfide were the most common compounds to exceed acute and other health-based risk levels. Air concentrations of potentially dangerous compounds and chemical mixtures are frequently present near oil and gas production sites. Community-based research can provide an

  2. Influence of wind-induced air pressure fluctuations on topsoil gas concentrations within a Scots pine forest

    NASA Astrophysics Data System (ADS)

    Mohr, Manuel; Laemmel, Thomas; Maier, Martin; Schindler, Dirk

    2017-04-01

    Commonly it is assumed that soil gas transport is dominated by molecular diffusion. Few recent studies indicate that the atmosphere above the soil triggers non-diffusive gas transport processes in the soil, which can enhance soil gas transport and therefore soil gas efflux significantly. During high wind speed conditions, the so called pressure pumping effect has been observed: the enhancement of soil gas transport through dynamic changes in the air pressure field above the soil. However, the amplitudes and frequencies of the air pressure fluctuations responsible for pressure pumping are still uncertain. Moreover, an in situ observation of the pressure pumping effect is still missing. To investigate the pressure pumping effect, airflow measurements above and below the canopy of a Scots pine forest and high-precision relative air pressure measurements were conducted in the below-canopy space and in the soil over a measurement period of 16 weeks. To monitor the soil gas transport, a newly developed gas measurement system was used. The gas measurement system continuously injects helium as a tracer gas into the soil until a diffusive steady state is reached. With the steady state concentration profile of the tracer gas, it is possible to inversely model the gas diffusion coefficient profile of the soil. If the gas diffusion coefficient profile differed from steady state, we deduced that the soil gas transport is not only diffusive, but also influenced by non-diffusive processes. Results show that the occurrence of small air pressure fluctuations is strongly dependent on the mean above-canopy wind speed. The wind-induced air pressure fluctuations have mean amplitudes up to 10 Pa and lie in the frequency range 0.01-0.1 Hz. To describe the pumping motion of the air pressure field, the pressure pumping coefficient (PPC) was defined as the mean change in pressure per second. The PPC shows a clear quadratic dependence on mean above-canopy wind speed. Empirical modelling of

  3. Temperature Programmed Desorption of Quench-condensed Krypton and Acetone in Air; Selective Concentration of Ultra-trace Gas Components.

    PubMed

    Suzuki, Taku T; Sakaguchi, Isao

    2016-01-01

    Selective concentration of ultra-trace components in air-like gases has an important application in analyzing volatile organic compounds in the gas. In the present study, we examined quench-condensation of the sample gas on a ZnO substrate below 50 K followed by temperature programmed desorption (TPD) (low temperature TPD) as a selective gas concentration technique. We studied two specific gases in the normal air; krypton as an inert gas and acetone as a reactive gas. We evaluated the relationship between the operating condition of low temperature TPD and the lowest detection limit. In the case of krypton, we observed the selective concentration by exposing at 6 K followed by thermal desorption at about 60 K. On the other hand, no selectivity appeared for acetone although trace acetone was successfully concentrated. This is likely due to the solvent effect by a major component in the air, which is suggested to be water. We suggest that pre-condensation to remove the water component may improve the selectivity in the trace acetone analysis by low temperature TPD.

  4. The Relationship Between Temperature and Gas Concentration Fluctuation Rates at an Air-Water Interface

    NASA Astrophysics Data System (ADS)

    Asher, W. E.; Jessup, A. T.; Liang, H.; Zappa, C. J.

    2008-12-01

    The air-sea flux, F, of a sparingly soluble nonreactive gas can be expressed as F = kG(CS-CW), where kG is the gas transfer velocity, CS is the concentration of gas that would be expected in the water if the system were in Henry's Gas Law equilibrium, and CW is the gas concentration in the bulk water. An analogous relationship for the net heat flux can also be written using the heat transfer velocity, kH, and the bulk-skin temperature difference in the aqueous phase. Surface divergence theory for the air-water transfer of gas and heat predicts that kG and kH will scale as the square root of the surface divergence rate, r. However, because of the interaction between diffusivity and the scale depth of the surface divergences, the scale factor for heat is likely to be different from the scale factor for gases. Infrared imagery was used to measure the timescales of variations in temperature at a water surface and laser-induced fluorescence (LIF) was used to measure temporal fluctuations in aqueous-phase concentrations of carbon dioxide (CO2) at a water surface. The rate at which these temperature and concentration fluctuations occur is then assumed to be related to r. The divergence rates derived for temperature from the IR images can be compared to the rates for gas derived from the LIF measurements to understand how r estimated from the two measurements differ. The square root of r is compared to concurrently measured kG for helium and sulfur hexafluoride to test the assumption that r1/2 scales with kG. Additionally, we measured kH using the active controlled flux technique, and those heat transfer velocities can also be used to test for a r1/2 dependence. All measurements reported here were made in the APL-UW synthetic jet array facility.

  5. Impact of radon gas concentration in the aerosoles profile

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lukaj, Edmond, E-mail: mondilukaj@yahoo.com; Vila, Floran, E-mail: floranvila@yahoo.com; Mandija, Florian, E-mail: fmandija@yahoo.com

    Radon gases relased from building materials and from earth surface are the major responsibility of air ionization. Radon nuclear decay can produce an alpha particle with high energy and Radon progeny. This particle and gamma rays can deliver particles in the air and produce ions with different polarities. This ions, because of induced electric charge, can attach with air aerosols and charge them with their electric charge. The charged aerosols can interact with the other aerosols and ions. Because of this exchange, the air conductivity and the aerosol profiles will change dependently by Radon gas concentration and gamma radiation. Observationsmore » show an increase in concentration of Radon during the night, and a decrease during the daylight time. The Radon gas concentration changed hour by hour can induce aerosol profile to change. This dependency between the aerosol profiles and the Radon gas concentrations is discussed.« less

  6. Atmospheric concentrations and air-soil gas exchange of polycyclic aromatic hydrocarbons (PAHs) in remote, rural village and urban areas of Beijing-Tianjin region, North China.

    PubMed

    Wang, Wentao; Simonich, Staci; Giri, Basant; Chang, Ying; Zhang, Yuguang; Jia, Yuling; Tao, Shu; Wang, Rong; Wang, Bin; Li, Wei; Cao, Jun; Lu, Xiaoxia

    2011-07-01

    Forty passive air samplers were deployed to study the occurrence of gas and particulate phase PAHs in remote, rural village and urban areas of Beijing-Tianjin region, North China for four seasons (spring, summer, fall and winter) from 2007 to 2008. The influence of emissions on the spatial distribution pattern of air PAH concentrations was addressed. In addition, the air-soil gas exchange of PAHs was studied using fugacity calculations. The median gaseous and particulate phase PAH concentrations were 222 ng/m³ and 114 ng/m³, respectively, with a median total PAH concentration of 349 ng/m³. Higher PAH concentrations were measured in winter than in other seasons. Air PAH concentrations measured at the rural villages and urban sites in the northern mountain region were significantly lower than those measured at sites in the southern plain during all seasons. However, there was no significant difference in PAH concentrations between the rural villages and urban sites in the northern and southern areas. This urban-rural PAH distribution pattern was related to the location of PAH emission sources and the population distribution. The location of PAH emission sources explained 56%-77% of the spatial variation in ambient air PAH concentrations. The annual median air-soil gas exchange flux of PAHs was 42.2 ng/m²/day from soil to air. Among the 15 PAHs measured, acenaphthylene (ACY) and acenaphthene (ACE) contributed to more than half of the total exchange flux. Furthermore, the air-soil gas exchange fluxes of PAHs at the urban sites were higher than those at the remote and rural sites. In summer, more gaseous PAHs volatilized from soil to air because of higher temperatures and increased rainfall. However, in winter, more gaseous PAHs deposited from air to soil due to higher PAH emissions and lower temperatures. The soil TOC concentration had no significant influence on the air-soil gas exchange of PAHs. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. A Gas Chromatographic System for the Detection of Ethylene Gas Using Ambient Air as a Carrier Gas

    PubMed Central

    Zaidi, Nayyer Abbas; Tahir, Muhammad Waseem; Vellekoop, Michael J.; Lang, Walter

    2017-01-01

    Ethylene gas is a naturally occurring gas that has an influence on the shelf life of fruit during their transportation in cargo ships. An unintentional exposure of ethylene gas during transportation results in a loss of fruit. A gas chromatographic system is presented here for the detection of ethylene gas. The gas chromatographic system was assembled using a preconcentrator, a printed 3D printed gas chromatographic column, a humidity sensor, solenoid valves, and an electrochemical ethylene gas sensor. Ambient air was used as a carrier gas in the gas chromatographic system. The flow rate was fixed to 10 sccm. It was generated through a mini-pump connected in series with a mass flow controller. The metal oxide gas sensor is discussed with its limitation in ambient air. The results show the chromatogram obtained from metal oxide gas sensor has low stability, drifts, and has uncertain peaks, while the chromatogram from the electrochemical sensor is stable and precise. Furthermore, ethylene gas measurements at higher ppb concentration and at lower ppb concentration were demonstrated with the electrochemical ethylene gas sensor. The system separates ethylene gas and humidity. The chromatograms obtained from the system are stable, and the results are 1.2% repeatable in five similar measurements. The statistical calculation of the gas chromatographic system shows that a concentration of 2.3 ppb of ethylene gas can be detected through this system. PMID:28991173

  8. A Gas Chromatographic System for the Detection of Ethylene Gas Using Ambient Air as a Carrier Gas.

    PubMed

    Zaidi, Nayyer Abbas; Tahir, Muhammad Waseem; Vellekoop, Michael J; Lang, Walter

    2017-10-07

    Ethylene gas is a naturally occurring gas that has an influence on the shelf life of fruit during their transportation in cargo ships. An unintentional exposure of ethylene gas during transportation results in a loss of fruit. A gas chromatographic system is presented here for the detection of ethylene gas. The gas chromatographic system was assembled using a preconcentrator, a printed 3D printed gas chromatographic column, a humidity sensor, solenoid valves, and an electrochemical ethylene gas sensor. Ambient air was used as a carrier gas in the gas chromatographic system. The flow rate was fixed to 10 sccm. It was generated through a mini-pump connected in series with a mass flow controller. The metal oxide gas sensor is discussed with its limitation in ambient air. The results show the chromatogram obtained from metal oxide gas sensor has low stability, drifts, and has uncertain peaks, while the chromatogram from the electrochemical sensor is stable and precise. Furthermore, ethylene gas measurements at higher ppb concentration and at lower ppb concentration were demonstrated with the electrochemical ethylene gas sensor. The system separates ethylene gas and humidity. The chromatograms obtained from the system are stable, and the results are 1.2% repeatable in five similar measurements. The statistical calculation of the gas chromatographic system shows that a concentration of 2.3 ppb of ethylene gas can be detected through this system.

  9. Contribution of solid fuel, gas combustion, or tobacco smoke to indoor air pollutant concentrations in Irish and Scottish homes.

    PubMed

    Semple, S; Garden, C; Coggins, M; Galea, K S; Whelan, P; Cowie, H; Sánchez-Jiménez, A; Thorne, P S; Hurley, J F; Ayres, J G

    2012-06-01

      There are limited data describing pollutant levels inside homes that burn solid fuel within developed country settings with most studies describing test conditions or the effect of interventions. This study recruited homes in Ireland and Scotland where open combustion processes take place. Open combustion was classified as coal, peat, or wood fuel burning, use of a gas cooker or stove, or where there is at least one resident smoker. Twenty-four-hour data on airborne concentrations of particulate matter<2.5 μm in size (PM2.5), carbon monoxide (CO), endotoxin in inhalable dust and carbon dioxide (CO2), together with 2-3 week averaged concentrations of nitrogen dioxide (NO2) were collected in 100 houses during the winter and spring of 2009-2010. The geometric mean of the 24-h time-weighted-average (TWA) PM2.5 concentration was highest in homes with resident smokers (99 μg/m3--much higher than the WHO 24-h guidance value of 25 μg/m3). Lower geometric mean 24-h TWA levels were found in homes that burned coal (7 μg/m3) or wood (6 μg/m3) and in homes with gas cookers (7 μg/m3). In peat-burning homes, the average 24-h PM2.5 level recorded was 11 μg/m3. Airborne endotoxin, CO, CO2, and NO2 concentrations were generally within indoor air quality guidance levels. Little is known about indoor air quality (IAQ) in homes that burn solid or fossil-derived fuels in economically developed countries. Recent legislative changes have moved to improve IAQ at work and in enclosed public places, but there remains a real need to begin the process of quantifying the health burden that arises from indoor air pollution within domestic environments. This study demonstrates that homes in Scotland and Ireland that burn solid fuels or gas for heating and cooking have concentrations of air pollutants generally within guideline levels. Homes where combustion of cigarettes takes place have much poorer air quality. © 2011 John Wiley & Sons A/S.

  10. CONCENTRATIONS OF TOXIC AIR POLLUTANTS IN THE U.S. SIMULATED BY AN AIR QUALITY MODEL

    EPA Science Inventory

    As part of the US National Air Toxics Assessment, we have applied the Community Multiscale Air Quality Model, CMAQ, to study the concentrations of twenty gas-phase, toxic, hazardous air pollutants (HAPs) in the atmosphere over the continental United States. We modified the Carbo...

  11. Indoor air quality inspection and analysis system based on gas sensor array

    NASA Astrophysics Data System (ADS)

    Gao, Xiang; Wang, Mingjiang; Fan, Binwen

    2017-08-01

    A detection and analysis system capable of measuring the concentration of four major gases in indoor air is designed. It uses four gas sensors constitute a gas sensor array, to achieve four indoor gas concentration detection, while the detection of data for further processing to reduce the cross-sensitivity between the gas sensor to improve the accuracy of detection.

  12. Air-gas exchange reevaluated: clinically important results of a computer simulation.

    PubMed

    Shunmugam, Manoharan; Shunmugam, Sudhakaran; Williamson, Tom H; Laidlaw, D Alistair

    2011-10-21

    The primary aim of this study was to evaluate the efficiency of air-gas exchange techniques and the factors that influence the final concentration of an intraocular gas tamponade. Parameters were varied to find the optimum method of performing an air-gas exchange in ideal circumstances. A computer model of the eye was designed using 3D software with fluid flow analysis capabilities. Factors such as angular distance between ports, gas infusion gauge, exhaust vent gauge and depth were varied in the model. Flow rate and axial length were also modulated to simulate faster injections and more myopic eyes, respectively. The flush volume of gas required to achieve a 97% intraocular gas fraction concentration were compared. Modulating individual factors did not reveal any clinically significant difference in the angular distance between ports, exhaust vent size, and depth or rate of gas injection. In combination, however, there was a 28% increase in air-gas exchange efficiency comparing the most efficient with the least efficient studied parameters in this model. The gas flush volume required to achieve a 97% gas fill also increased proportionately at a ratio of 5.5 to 6.2 times the volume of the eye. A 35-mL flush is adequate for eyes up to 25 mm in axial length; however, eyes longer than this would require a much greater flush volume, and surgeons should consider using two separate 50-mL gas syringes to ensure optimal gas concentration for eyes greater than 25 mm in axial length.

  13. Fractional kalman filter to estimate the concentration of air pollution

    NASA Astrophysics Data System (ADS)

    Vita Oktaviana, Yessy; Apriliani, Erna; Khusnul Arif, Didik

    2018-04-01

    Air pollution problem gives important effect in quality environment and quality of human’s life. Air pollution can be caused by nature sources or human activities. Pollutant for example Ozone, a harmful gas formed by NOx and volatile organic compounds (VOCs) emitted from various sources. The air pollution problem can be modeled by TAPM-CTM (The Air Pollution Model with Chemical Transport Model). The model shows concentration of pollutant in the air. Therefore, it is important to estimate concentration of air pollutant. Estimation method can be used for forecast pollutant concentration in future and keep stability of air quality. In this research, an algorithm is developed, based on Fractional Kalman Filter to solve the model of air pollution’s problem. The model will be discretized first and then it will be estimated by the method. The result shows that estimation of Fractional Kalman Filter has better accuracy than estimation of Kalman Filter. The accuracy was tested by applying RMSE (Root Mean Square Error).

  14. Biofiltration of air contaminated by styrene: Effect of nitrogen supply, gas flow rate, and inlet concentration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jorio, H.; Bibeau, L.; Heitz, M.

    2000-05-01

    The biofiltration process is a promising technology for the treatment of dilute styrene emissions in air. The efficiency of this process is however strongly dependent upon various operational parameters such as the filter bed characteristics, nutrient supplies, input contaminant concentrations, and gas flow rates. The biofiltration of air containing styrene vapors was therefore investigated, employing a novel biomass filter material, in two identical but separate laboratory scale biofiltration units (units 1 and 2), both biofilters being initially inoculated with a microbial consortium. Each biofilter was irrigated with a nutrient solution supplying nitrogen in one of two forms; i.e., mainly asmore » ammonia for unit 1 and exclusively as nitrate for unit 2. The experimental results have revealed that greater styrene elimination rates are achieved in the biofilter supplied with ammonia as the major nitrogen source in comparison to the lesser elimination performance obtained with the nitrate provided biofilter. However, in achieving the high styrene removal rates in the ammonia supplied biofilter, the excess of biomass accumulates on the filtering pellets and causes progressive clogging of the filter media. Furthermore, the effectiveness of nitrate supply as the sole nitrogen nutrient form, on reducing or controlling the biomass accumulation in the filter media in comparison to ammonia, could not be satisfactorily demonstrated because the two biofilters operated with very different styrene elimination capacities. The monitoring of the carbon dioxide concentration profile through both biofilters revealed that the ratio of carbon dioxide produced to the styrene removed was approximately 3/1, which confirms the complete biodegradation of removed styrene, given that some of the organic carbon consumed is also used for the microbial growth. The effects of the most important design parameters, namely styrene input concentrations and gas flow rates, were investigated for

  15. Control of gas contaminants in air streams through biofiltration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Holt, T.; Lackey, L.

    1996-11-01

    According to the National Institute for Occupational Safety and Health (NIOSH), the maximum styrene concentration allowed in the work place is 50 ppm for up to a 10-hour work day during a 40-hour work week. The US EPA has classified styrene as one of the 189 hazardous air pollutants listed under Title 3 of the Clean Air Act Amendments to be reduced by a factor of 90% by the year 2000. Significant quantities of styrene are emitted to the atmosphere each year by boat manufacturers. A typical fiberglass boat manufacturing facility can emit over 273 metric tons/year of styrene. Themore » concentration of styrene in the industrial exhaust gas ranges from 20 to 100 ppmv. Such dilute, high volume organically tainted air streams can make conventional abatement technologies such as thermal incineration, adsorption, or absorption technically incompetent or prohibitively expensive. An efficient, innovative, and economical means of remediating styrene vapors would be of value to industries and to the environment. Biofilter technology depends on microorganisms that are immobilized on the packing material in a solid phase reactor to remove or degrade environmentally undesirable compounds contaminating gas streams. The technology is especially successful for treating large volumes of air containing low concentrations of contaminants. The objective of this study was to investigate the feasibility of using biofiltration to treat waste gas streams containing styrene and to determine the critical design and operating parameters for such a system.« less

  16. Measurement of radon concentration in super-Kamiokande's buffer gas

    NASA Astrophysics Data System (ADS)

    Nakano, Y.; Sekiya, H.; Tasaka, S.; Takeuchi, Y.; Wendell, R. A.; Matsubara, M.; Nakahata, M.

    2017-09-01

    To precisely measure radon concentrations in purified air supplied to the Super-Kamiokande detector as a buffer gas, we have developed a highly sensitive radon detector with an intrinsic background as low as 0 . 33 ± 0 . 07 mBq /m3. In this article, we discuss the construction and calibration of this detector as well as results of its application to the measurement and monitoring of the buffer gas layer above Super-Kamiokande. In March 2013, the chilled activated charcoal system used to remove radon in the input buffer gas was upgraded. After this improvement, a dramatic reduction in the radon concentration of the supply gas down to 0 . 08 ± 0 . 07 mBq /m3. Additionally, the Rn concentration of the in-situ buffer gas has been measured 28 . 8 ± 1 . 7 mBq /m3 using the new radon detector. Based on these measurements we have determined that the dominant source of Rn in the buffer gas arises from contamination from the Super-Kamiokande tank itself.

  17. Quality assured measurements of animal building emissions: gas concentrations.

    PubMed

    Heber, Albert J; Ni, Ji-Qin; Lim, Teng T; Tao, Pei-Chun; Schmidt, Amy M; Koziel, Jacek A; Beasley, David B; Hoff, Steven J; Nicolai, Richard E; Jacobson, Larry D; Zhang, Yuanhui

    2006-10-01

    Comprehensive field studies were initiated in 2002 to measure emissions of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), methane (CH4), nonmethane hydrocarbons (NMHC), particulate matter <10 microm in diameter, and total suspended particulate from swine and poultry production buildings in the United States. This paper focuses on the quasicontinuous gas concentration measurement at multiple locations among paired barns in seven states. Documented principles, used in air pollution monitoring at industrial sources, were applied in developing quality assurance (QA) project plans for these studies. Air was sampled from multiple locations with each gas analyzed with one high quality commercial gas analyzer that was located in an environmentally controlled on-farm instrument shelter. A nominal 4 L/min gas sampling system was designed and constructed with Teflon wetted surfaces, bypass pumping, and sample line flow and pressure sensors. Three-way solenoids were used to automatically switch between multiple gas sampling lines with > or =10 min sampling intervals. Inside and outside gas sampling probes were between 10 and 115 m away from the analyzers. Analyzers used chemiluminescence, fluorescence, photoacoustic infrared, and photoionization detectors for NH3, H2S, CO2, CH4, and NMHC, respectively. Data were collected using personal computer-based data acquisition hardware and software. This paper discusses the methodology of gas concentration measurements and the unique challenges that livestock barns pose for achieving desired accuracy and precision, data representativeness, comparability and completeness, and instrument calibration and maintenance.

  18. Results of the California Healthy Homes Indoor Air Quality Study of 2011-2013: impact of natural gas appliances on air pollutant concentrations.

    PubMed

    Mullen, N A; Li, J; Russell, M L; Spears, M; Less, B D; Singer, B C

    2016-04-01

    This study was conducted to assess the current impact of natural gas appliances on air quality in California homes. Data were collected via telephone interviews and measurements inside and outside of 352 homes. Passive samplers measured time-resolved CO and time-integrated NOX , NO2 , formaldehyde, and acetaldehyde over ~6-day periods in November 2011 - April 2012 and October 2012 - March 2013. The fraction of indoor NOX and NO2 attributable to indoor sources was estimated. NOX , NO2 , and highest 1-h CO were higher in homes that cooked with gas and increased with amount of gas cooking. NOX and NO2 were higher in homes with cooktop pilot burners, relative to gas cooking without pilots. Homes with a pilot burner on a floor or wall furnace had higher kitchen and bedroom NOX and NO2 compared to homes without a furnace pilot. When scaled to account for varying home size and mixing volume, indoor-attributed bedroom and kitchen NOX and kitchen NO2 were not higher in homes with wall or floor furnace pilot burners, although bedroom NO2 was higher. In homes that cooked 4 h or more with gas, self-reported use of kitchen exhaust was associated with lower NOX , NO2 , and highest 1-h CO. Gas appliances were not associated with higher concentrations of formaldehyde or acetaldehyde. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Results of the California Healthy Homes Indoor Air Quality Study of 2011-2013: Impact of natural gas appliances on air pollutant concentrations

    DOE PAGES

    Mullen, Nasim A.; Li, Jina; Russell, Marion L.; ...

    2015-03-17

    This study was conducted to assess the current impact of natural gas appliances on air quality in California homes. Data were collected via telephone interviews and measurements inside and outside of 352 homes. Passive samplers measured time-resolved CO and time-integrated NO X, NO 2, formaldehyde, and acetaldehyde over ~6d periods in November 2011 - April 2012 and October 2012 - March 2013. The fraction of indoor NO X and NO 2 attributable to indoor sources was estimated. NO X, NO 2 and highest 1-h CO were higher in homes that cooked with gas and increased with amount of gas cooking.more » NO X and NO 2 were higher in homes with cooktop pilot burners, relative to gas cooking without pilots. Homes with a pilot burner on a floor or wall furnace had higher kitchen and bedroom NO X and NO 2 compared to homes without a furnace pilot. When scaled to account for varying home size and mixing volume, indoor-attributed bedroom and kitchen NO X and kitchen NO 2 were not higher in homes with wall or floor furnace pilot burners, though bedroom NO 2 was higher. In homes that cooked 4 h or more with gas, self-reported use of kitchen exhaust was associated with lower NO X, NO 2 and highest 1-h CO. Gas appliances were not associated with higher concentrations of formaldehyde or acetaldehyde.« less

  20. Results of the California Healthy Homes Indoor Air Quality Study of 2011-2013: Impact of natural gas appliances on air pollutant concentrations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mullen, Nasim A.; Li, Jina; Russell, Marion L.

    This study was conducted to assess the current impact of natural gas appliances on air quality in California homes. Data were collected via telephone interviews and measurements inside and outside of 352 homes. Passive samplers measured time-resolved CO and time-integrated NO X, NO 2, formaldehyde, and acetaldehyde over ~6d periods in November 2011 - April 2012 and October 2012 - March 2013. The fraction of indoor NO X and NO 2 attributable to indoor sources was estimated. NO X, NO 2 and highest 1-h CO were higher in homes that cooked with gas and increased with amount of gas cooking.more » NO X and NO 2 were higher in homes with cooktop pilot burners, relative to gas cooking without pilots. Homes with a pilot burner on a floor or wall furnace had higher kitchen and bedroom NO X and NO 2 compared to homes without a furnace pilot. When scaled to account for varying home size and mixing volume, indoor-attributed bedroom and kitchen NO X and kitchen NO 2 were not higher in homes with wall or floor furnace pilot burners, though bedroom NO 2 was higher. In homes that cooked 4 h or more with gas, self-reported use of kitchen exhaust was associated with lower NO X, NO 2 and highest 1-h CO. Gas appliances were not associated with higher concentrations of formaldehyde or acetaldehyde.« less

  1. Variability of air ion concentrations in urban Paris

    NASA Astrophysics Data System (ADS)

    Dos Santos, V. N.; Herrmann, E.; Manninen, H. E.; Hussein, T.; Hakala, J.; Nieminen, T.; Aalto, P. P.; Merkel, M.; Wiedensohler, A.; Kulmala, M.; Petäjä, T.; Hämeri, K.

    2015-12-01

    Air ion concentrations influence new particle formation and consequently the global aerosol as potential cloud condensation nuclei. We aimed to evaluate air ion concentrations and characteristics of new particle formation events (NPF) in the megacity of Paris, France, within the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric Pollution and climate effects, and Integrated tools for assessment and mitigation) project. We measured air ion number size distributions (0.8-42 nm) with an air ion spectrometer and fine particle number concentrations (> 6 nm) with a twin differential mobility particle sizer in an urban site of Paris between 26 June 2009 and 4 October 2010. Air ions were size classified as small (0.8-2 nm), intermediate (2-7 nm), and large (7-20 nm). The median concentrations of small and large ions were 670 and 680 cm-3, respectively, (sum of positive and negative polarities), whereas the median concentration of intermediate ions was only 20 cm-3, as these ions were mostly present during new particle formation bursts, i.e. when gas-to-particle conversion produced fresh aerosol particles from gas phase precursors. During peaks in traffic-related particle number, the concentrations of small and intermediate ions decreased, whereas the concentrations of large ions increased. Seasonal variations affected the ion population differently, with respect to their size and polarity. NPF was observed in 13 % of the days, being most frequent in spring and late summer (April, May, July, and August). The results also suggest that NPF was favoured on the weekends in comparison to workdays, likely due to the lower levels of condensation sinks in the mornings of weekends (CS weekdays 09:00: 18 × 10-3 s-1; CS weekend 09:00: 8 × 10-3 s-1). The median growth rates (GR) of ions during the NPF events varied between 3 and 7 nm h-1, increasing with the ion size and being higher on workdays than on weekends for intermediate and large ions. The median GR of

  2. Irreversible sorption of trace concentrations of perfluorocarboxylic acids to fiber filters used for air sampling

    NASA Astrophysics Data System (ADS)

    Arp, Hans Peter H.; Goss, Kai-Uwe

    Due to the apparent environmental omnipresence of perfluorocarboxylic acids (PFAs), an increasing number of researchers are investigating their ambient particle- and gas-phase concentrations. Typically this is done using a high-volume air sampler equipped with Quartz Fiber Filters (QFFs) or Glass Fiber Filters (GFFs) to sample the particle-bound PFAs and downstream sorbents to sample the gas-phase PFAs. This study reports that at trace, ambient concentrations gas-phase PFAs sorb to QFFs and GFFs irreversibly and hardly pass through these filters to the downstream sorbents. As a consequence, it is not possible to distinguish between particle- and gas-phase concentrations, or to distinguish concentrations on different particle size fractions, unless precautions are taken. Failure to take such precautions could have already caused reported data to be misinterpreted. Here it is also reported that deactivating QFFs and GFFs with a silylating agent renders them suitable for sampling PFAs. Based on the presented study, a series of recommendations for air-sampling PFAs are provided.

  3. Continuous measurement of air-water gas exchange by underwater eddy covariance

    NASA Astrophysics Data System (ADS)

    Berg, Peter; Pace, Michael L.

    2017-12-01

    Exchange of gases, such as O2, CO2, and CH4, over the air-water interface is an important component in aquatic ecosystem studies, but exchange rates are typically measured or estimated with substantial uncertainties. This diminishes the precision of common ecosystem assessments associated with gas exchanges such as primary production, respiration, and greenhouse gas emission. Here, we used the aquatic eddy covariance technique - originally developed for benthic O2 flux measurements - right below the air-water interface (˜ 4 cm) to determine gas exchange rates and coefficients. Using an acoustic Doppler velocimeter and a fast-responding dual O2-temperature sensor mounted on a floating platform the 3-D water velocity, O2 concentration, and temperature were measured at high-speed (64 Hz). By combining these data, concurrent vertical fluxes of O2 and heat across the air-water interface were derived, and gas exchange coefficients were calculated from the former. Proof-of-concept deployments at different river sites gave standard gas exchange coefficients (k600) in the range of published values. A 40 h long deployment revealed a distinct diurnal pattern in air-water exchange of O2 that was controlled largely by physical processes (e.g., diurnal variations in air temperature and associated air-water heat fluxes) and not by biological activity (primary production and respiration). This physical control of gas exchange can be prevalent in lotic systems and adds uncertainty to assessments of biological activity that are based on measured water column O2 concentration changes. For example, in the 40 h deployment, there was near-constant river flow and insignificant winds - two main drivers of lotic gas exchange - but we found gas exchange coefficients that varied by several fold. This was presumably caused by the formation and erosion of vertical temperature-density gradients in the surface water driven by the heat flux into or out of the river that affected the turbulent

  4. 222Rn and 220Rn concentrations in soil gas of Karkonosze-Izera Block (Sudetes, Poland).

    PubMed

    Malczewski, Dariusz; Zaba, Jerzy

    2007-01-01

    Soil gas 222Rn and 220Rn concentrations were measured at 18 locations in the Karkonosze-Izera Block area in southwestern Poland. Measurements were carried out in surface air and at sampling depths of 10, 40 and 80 cm. Surface air 222Rn concentrations ranged from 4 to 2160 Bq m(-3) and 220Rn ranged from 4 to 228 Bq m(-3). The concentrations for 10 and 40 cm varied from 142 Bq m(-3) to 801 kBq m(-3) and 102 Bq m(-3) to 64 kBq m(-3) for 222Rn and 220Rn, respectively. At 80 cm 222Rn concentrations ranged from 94 Bq m(-3) to >1 MBq m(-3). The 220Rn concentrations at 80 cm varied from 45 Bq m(-3) to 48 kBq m(-3). The concentration versus depth profiles for 222Rn differed for soils developed on fault zones, uranium deposits or both. Atmospheric air temperature and soil gas 222Rn and 220Rn were negatively correlated. At sampling sites with steep slopes, 220Rn concentrations decreased with depth.

  5. Surfactant control of air-sea gas exchange across contrasting biogeochemical regimes

    NASA Astrophysics Data System (ADS)

    Pereira, Ryan; Schneider-Zapp, Klaus; Upstill-Goddard, Robert

    2014-05-01

    Air-sea gas exchange is important to the global partitioning of CO2.Exchange fluxes are products of an air-sea gas concentration difference, ΔC, and a gas transfer velocity, kw. The latter is controlled by the rate of turbulent diffusion at the air-sea interface but it cannot be directly measured and has a high uncertainty that is now considered one of the greatest challenges to quantifying net global air-sea CO2 exchange ...(Takahashi et al., 2009). One important control on kw is exerted by sea surface surfactants that arise both naturally from biological processes and through anthropogenic activity. They influence gas exchange in two fundamental ways: as a monolayer physical barrier and through modifying sea surface hydrodynamics and hence turbulent energy transfer. These effects have been demonstrated in the laboratory with artificial surfactants ...(Bock et al., 1999; Goldman et al., 1988) and through purposeful surfactant releases in coastal waters .(.).........().(Brockmann et al., 1982) and in the open ocean (Salter et al., 2011). Suppression of kwin these field experiments was ~5-55%. While changes in both total surfactant concentration and the composition of the natural surfactant pool might be expected to impact kw, the required in-situ studies are lacking. New data collected from the coastal North Sea in 2012-2013 shows significant spatio-temporal variability in the surfactant activity of organic matter within the sea surface microlayer that ranges from 0.07-0.94 mg/L T-X-100 (AC voltammetry). The surfactant activities show a strong winter/summer seasonal bias and general decrease in concentration with increasing distance from the coastline possibly associated with changing terrestrial vs. phytoplankton sources. Gas exchange experiments of this seawater using a novel laboratory tank and gas tracers (CH4 and SF6) demonstrate a 12-45% reduction in kw compared to surfactant-free water. Seasonally there is higher gas exchange suppression in the summer

  6. Nondestructive natural gas hydrate recovery driven by air and carbon dioxide.

    PubMed

    Kang, Hyery; Koh, Dong-Yeun; Lee, Huen

    2014-10-14

    Current technologies for production of natural gas hydrates (NGH), which include thermal stimulation, depressurization and inhibitor injection, have raised concerns over unintended consequences. The possibility of catastrophic slope failure and marine ecosystem damage remain serious challenges to safe NGH production. As a potential approach, this paper presents air-driven NGH recovery from permeable marine sediments induced by simultaneous mechanisms for methane liberation (NGH decomposition) and CH₄-air or CH₄-CO₂/air replacement. Air is diffused into and penetrates NGH and, on its surface, forms a boundary between the gas and solid phases. Then spontaneous melting proceeds until the chemical potentials become equal in both phases as NGH depletion continues and self-regulated CH4-air replacement occurs over an arbitrary point. We observed the existence of critical methane concentration forming the boundary between decomposition and replacement mechanisms in the NGH reservoirs. Furthermore, when CO₂ was added, we observed a very strong, stable, self-regulating process of exchange (CH₄ replaced by CO₂/air; hereafter CH₄-CO₂/air) occurring in the NGH. The proposed process will work well for most global gas hydrate reservoirs, regardless of the injection conditions or geothermal gradient.

  7. Air Data - Concentration Map

    EPA Pesticide Factsheets

    Make a map of daily concentrations over several days. The daily air quality can be displayed in terms of the Air Quality Index or in concentration ranges for certain PM species like organic carbon, nitrates, and sulfates.

  8. Impacts of winter storms on air-sea gas exchange

    NASA Astrophysics Data System (ADS)

    Zhang, Weiqing; Perrie, Will; Vagle, Svein

    2006-07-01

    The objective of this study is to investigate air-sea gas exchange during winter storms, using field measurements from Ocean Station Papa in the Northeast Pacific (50°N, 145°W). We show that increasing gas transfer rates are coincident with increasing winds and deepening depth of bubble penetration, and that this process depends on sea state. Wave-breaking is shown to be an important factor in the gas transfer velocity during the peaks of the storms, increasing the flux rates by up to 20%. Gas transfer rates and concentrations can exhibit asymmetry, reflecting a sudden increase with the onset of a storm, and gradual recovery stages.

  9. USING THE AIR QUALITY MODEL TO ANALYZE THE CONCENTRATIONS OF AIR TOXICS OVER THE CONTINENTAL U.S.

    EPA Science Inventory

    The U.S. Environmental Protection Agency is examining the concentrations and deposition of hazardous air pollutants (HAPs), which include a large number of chemicals, ranging from non reactive (i.e. carbon tetrachloride) to reactive (i.e. formaldehyde), exist in gas, aqueous, and...

  10. Modeling to Evaluate Contribution of Oil and Gas Emissions to Air Pollution.

    PubMed

    Thompson, Tammy M; Shepherd, Donald; Stacy, Andrea; Barna, Michael G; Schichtel, Bret A

    2017-04-01

    Oil and gas production in the Western United States has increased considerably over the past 10 years. While many of the still limited oil and gas impact assessments have focused on potential human health impacts, the typically remote locations of production in the Intermountain West suggests that the impacts of oil and gas production on national parks and wilderness areas (Class I and II areas) could also be important. To evaluate this, we utilize the Comprehensive Air quality Model with Extensions (CAMx) with a year-long modeling episode representing the best available representation of 2011 meteorology and emissions for the Western United States. The model inputs for the 2011 episodes were generated as part of the Three State Air Quality Study (3SAQS). The study includes a detailed assessment of oil and gas (O&G) emissions in Western States. The year-long modeling episode was run both with and without emissions from O&G production. The difference between these two runs provides an estimate of the contribution of the O&G production to air quality. These data were used to assess the contribution of O&G to the 8 hour average ozone concentrations, daily and annual fine particulate concentrations, annual nitrogen deposition totals and visibility in the modeling domain. We present the results for the Class I and II areas in the Western United States. Modeling results suggest that emissions from O&G activity are having a negative impact on air quality and ecosystem health in our National Parks and Class I areas. In this research, we use a modeling framework developed for oil and gas evaluation in the western United States to determine the modeled impacts of emissions associated with oil and gas production on air pollution metrics. We show that oil and gas production may have a significant negative impact on air quality and ecosystem health in some national parks and other Class I areas in the western United States. Our findings are of particular interest to federal

  11. Seasonal variation of indoor and outdoor air quality of nitrogen dioxide in homes with gas and electric stoves.

    PubMed

    Dėdelė, Audrius; Miškinytė, Auksė

    2016-09-01

    Indoor air pollution significantly influences personal exposure to air pollution and increases health risks. Nitrogen dioxide (NO2) is one of the major air pollutants, and therefore it is important to properly determine indoor concentration of this pollutant considering the fact that people spend most of their time inside. The aim of this study was to assess indoor and outdoor concentration of NO2 during each season; for this purpose, passive sampling was applied. We analyzed homes with gas and electric stoves to determine and compare the concentrations of NO2 in kitchen, living room, and bedroom microenvironments (MEs). The accuracy of passive sampling was evaluated by comparing the sampling results with the data from air quality monitoring stations. The highest indoor concentration of NO2 was observed in kitchen ME during the winter period, the median concentration being 28.4 μg m(-3). Indoor NO2 levels in homes with gas stoves were higher than outdoor levels during all seasons. The concentration of NO2 was by 2.5 times higher in kitchen MEs with gas stoves than with electric stoves. This study showed that the concentration of NO2 in indoor MEs mainly depended on the stove type used in the kitchen. Homes with gas stoves had significantly higher levels of NO2 in all indoor MEs compared with homes where electric stoves were used.

  12. Nondestructive natural gas hydrate recovery driven by air and carbon dioxide

    PubMed Central

    Kang, Hyery; Koh, Dong-Yeun; Lee, Huen

    2014-01-01

    Current technologies for production of natural gas hydrates (NGH), which include thermal stimulation, depressurization and inhibitor injection, have raised concerns over unintended consequences. The possibility of catastrophic slope failure and marine ecosystem damage remain serious challenges to safe NGH production. As a potential approach, this paper presents air-driven NGH recovery from permeable marine sediments induced by simultaneous mechanisms for methane liberation (NGH decomposition) and CH4-air or CH4-CO2/air replacement. Air is diffused into and penetrates NGH and, on its surface, forms a boundary between the gas and solid phases. Then spontaneous melting proceeds until the chemical potentials become equal in both phases as NGH depletion continues and self-regulated CH4-air replacement occurs over an arbitrary point. We observed the existence of critical methane concentration forming the boundary between decomposition and replacement mechanisms in the NGH reservoirs. Furthermore, when CO2 was added, we observed a very strong, stable, self-regulating process of exchange (CH4 replaced by CO2/air; hereafter CH4-CO2/air) occurring in the NGH. The proposed process will work well for most global gas hydrate reservoirs, regardless of the injection conditions or geothermal gradient. PMID:25311102

  13. Concentration-dependence of the explosion characteristics of chlorine dioxide gas.

    PubMed

    Jin, Ri-ya; Hu, Shuang-qi; Zhang, Yin-ghao; Bo, Tao

    2009-07-30

    The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 20 L. The experimental results have indicated that the lower concentration limit for the explosive decomposition of chlorine dioxide gas is 9.5% ([ClO(2)]/[air]), whereas there is no corresponding upper concentration limit. Under the experimental conditions, and within the explosion limits, the pressure of explosion increases with increasing concentration of chlorine dioxide gas; the maximum pressure of explosion relative to the initial pressure was measured as 0.024 MPa at 10% ClO(2) and 0.641 MPa at 90% ClO(2). The induction time (the time from the moment of sparking to explosion) has also been found to depend on the concentration of chlorine dioxide gas; thus, at 10% ClO(2) the induction time was 2195 ms, but at 90% ClO(2) the induction time was just 8 ms. The explosion reaction mechanism of ClO(2) is of a degenerate chain-branching type involving the formation of a stable intermediate (Cl(2)O(3)), from which the chain-branching occurs. Chain initiation takes place at the point of ignition and termination takes place at the inner walls of the exploder.

  14. Contribution of solid fuel, gas combustion or tobacco smoke to indoor air pollutant concentrations in Irish and Scottish homes

    PubMed Central

    Semple, S; Garden, C; Coggins, M; Galea, KS; Whelan, P; Cowie, H; Sánchez-Jimenéz, A; Thorne, PS; Hurley, JF; Ayres, JG

    2012-01-01

    There are limited data describing pollutant levels inside homes that burn solid fuel within developed country settings with most studies describing test conditions or the effect of interventions. This study recruited homes in Ireland and Scotland where open combustion processes take place. Open combustion was classified as coal, peat or wood fuel burning, use of a gas cooker or stove, or where there is at least one resident smoker. 24-hour data on airborne concentrations of particulate matter less than 2.5 microns in size (PM2.5), carbon monoxide (CO), endotoxin in inhalable dust and carbon dioxide (CO2), together with 2–3 week averaged concentrations of nitrogen dioxide (NO2) were collected in 100 houses during the winter and spring of 2009–2010. The geometric mean of the 24-hour time-weighted-average (TWA) PM2.5 concentration was highest in homes with resident smokers (99μg/m3 – much higher than the WHO 24-hour guidance value of 25 μg/m3. Lower geometric mean 24-hour TWA levels were found in homes that burned coal (7 μg/m3) or wood (6 μg/m3) and in homes with gas cookers (7 μg/m3). In peat-burning homes the average 24-hourPM2.5 level recorded was 11 μg/m3. Airborne endotoxin, CO, CO2 and NO2 concentrations were generally within indoor air quality guidance levels. PMID:22007695

  15. Preliminary experimental results of gas recycling subsystems except carbon dioxide concentration

    NASA Astrophysics Data System (ADS)

    Otsuji, K.; Sawada, T.; Satoh, S.; Kanda, S.; Matsumura, H.; Kondo, S.; Otsubo, K.

    Oxygen concentration and separation is an essential factor for air recycling in a CELSS. Furthermore, if the value of the plant assimilatory quotient is not coincident with that of the animal respiratory quotient, the recovery of O2 from the concentrated CO2 through chemical methods will become necessary to balance the gas contents in a CELSS. Therefore, oxygen concentration and separation equipment using Salcomine and O2 recovery equipment, such as Sabatier and Bosch reactors, were experimentally developed and tested.

  16. Observations on using inside air concentrations as a predictor of outside air concentrations

    DOE PAGES

    Hawkley, Gavin; Whicker, Jeffrey; Harris, Jason

    2015-04-01

    Here, excavations of radiological material were performed within confined structures with known operational parameters, such as a filtered exhaust system with known filtration efficiency. Given the known efficiency, the assumption could be made that the air concentrations of radioactivity measured outside the structure would be proportional to the air concentrations measured inside the structure. To investigate this assumption, the inside concentration data was compared with the outside concentration data. The correlation of the data suggested that the inside concentrations were not a good predictor of the outside concentrations. This poor correlation was deemed to be a result of operational unknownsmore » within the structures.« less

  17. Preliminary experimental results of gas recycling subsystems except carbon dioxide concentration

    NASA Technical Reports Server (NTRS)

    Otsuji, K.; Sawada, T.; Satoh, S.; Kanda, S.; Matsumura, H.; Kondo, S.; Otsubo, K.

    1987-01-01

    Oxygen concentration and separation is an essential factor for air recycling in a controlled ecological life support system (CELSS). Furthermore, if the value of the plant assimilatory quotient is not coincident with that of the animal respiratory quotient, the recovery of oxygen from the concentrated CO2 through chemical methods will become necessary to balance the gas contents in a CELSS. Therefore, oxygen concentration and separation equipment using Salcomine and O2 recovery equipment, such as Sabatier and Bosch reactors, were experimentally developed and tested.

  18. Measurement of gas species, temperatures, coal burnout, and wall heat fluxes in a 200 MWe lignite-fired boiler with different overfire air damper openings

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jianping Jing; Zhengqi Li; Guangkui Liu

    Measurements were performed on a 200 MWe, wall-fired, lignite utility boiler. For different overfire air (OFA) damper openings, the gas temperature, gas species concentration, coal burnout, release rates of components (C, H, and N), furnace temperature, and heat flux and boiler efficiency were measured. Cold air experiments for a single burner were conducted in the laboratory. The double-swirl flow pulverized-coal burner has two ring recirculation zones starting in the secondary air region in the burner. As the secondary air flow increases, the axial velocity of air flow increases, the maxima of radial velocity, tangential velocity and turbulence intensity all increase,more » and the swirl intensity of air flow and the size of recirculation zones increase slightly. In the central region of the burner, as the OFA damper opening widens, the gas temperature and CO concentration increase, while the O{sub 2} concentration, NOx concentration, coal burnout, and release rates of components (C, H, and N) decrease, and coal particles ignite earlier. In the secondary air region of the burner, the O{sub 2} concentration, NOx concentration, coal burnout, and release rates of components (C, H, and N) decrease, and the gas temperature and CO concentration vary slightly. In the sidewall region, the gas temperature, O{sub 2} concentration, and NOx concentration decrease, while the CO concentration increases and the gas temperature varies slightly. The furnace temperature and heat flux in the main burning region decrease appreciably, but increase slightly in the burnout region. The NOx emission decreases from 1203.6 mg/m{sup 3} (6% O{sub 2}) for a damper opening of 0% to 511.7 mg/m{sup 3} (6% O{sub 2}) for a damper opening of 80% and the boiler efficiency decreases from 92.59 to 91.9%. 15 refs., 17 figs., 3 tabs.« less

  19. Sensor gas analyzer for acetone determination in expired air

    NASA Astrophysics Data System (ADS)

    Baranov, Vitaly V.

    2001-05-01

    Diseases and changes in the way of life change the concentration and composition of the expired air. Our adaptable gas analyzer is intended for the selective analysis of expired air and can be adapted for the solution of current diagnostic and analytical tasks by the user (a physician or a patient). Having analyzed the existing trends in the development of noninvasive diagnostics we have chosen the method of noninvasive acetone detection in expired air, where the acetone concentration correlates with blood and urine glucose concentrations. The appearance of acetone in expired air is indicative of disorders that may be caused not only by diabetes but also be wrong diet, incorrect sportsmen training etc. To control the disorders one should know the acetone concentration in the human body. This knowledge allows one to judge upon the state of the patient, choose a correct diet that will not cause damage to the patient's health, determine sportsmen training efficiency and results and solve the artificial pancreas problem. Our device provide highly accurate analysis, rapid diagnostics and authentic acetone quantification in the patient's body at any time aimed at prediction of the patient's state and assessing the efficiency of the therapy used. Clinical implementation of the device will improve the health and save lives of many thousands of diabetes sufferers.

  20. Gas concentration cells for utilizing energy

    DOEpatents

    Salomon, Robert E.

    1987-01-01

    An apparatus and method for utilizing energy, in which the apparatus may be used for generating electricity or as a heat pump. When used as an electrical generator, two gas concentration cells are connected in a closed gas circuit. The first gas concentration cell is heated and generates electricity. The second gas concentration cell repressurizes the gas which travels between the cells. The electrical energy which is generated by the first cell drives the second cell as well as an electrical load. When used as a heat pump, two gas concentration cells are connected in a closed gas circuit. The first cell is supplied with electrical energy from a direct current source and releases heat. The second cell absorbs heat. The apparatus has no moving parts and thus approximates a heat engine.

  1. Effects of Outside Air Temperature on Movement of Phosphine Gas in Concrete Elevator Bins

    USDA-ARS?s Scientific Manuscript database

    Studies that measured the movement and concentration of phosphine gas in upright concrete bins over time indicated that fumigant movement was dictated by air currents, which in turn, were a function of the difference between the average grain temperature and the average outside air temperature durin...

  2. Concentrations in air of organobromine, organochlorine and organophosphate flame retardants in Toronto, Canada

    NASA Astrophysics Data System (ADS)

    Shoeib, Mahiba; Ahrens, Lutz; Jantunen, Liisa; Harner, Tom

    2014-12-01

    Concentrations of organobromine (BFRs), organochlorine (CFRs) and organophosphate esters flame retardants and plasticizers (PFRs) in air were monitored for over one year at an urban site in Toronto, Canada during 2010-2011. The mean value for polybrominated diphenyl ethers (BDEs) (gas + particle phase) was 38 pg/m3 with BDE-47 and BDE-99 as the dominant congeners. The mean concentrations in air for ∑non-BDE (BFRs and CFRs), was 9.6 pg/m3 - about four times lower than the BDEs. The brominated FRs: TBP-AE, BTBPE, EH-TBB, BEH-TEBP and the chlorinated syn- and anti-DP were detected frequently, ranging from 87% to 96%. Highest concentrations in air among all flame retardant classes were observed for the Σ-PFRs. The yearly mean concentration in air for ΣPFRs was 2643 pg/m3 with detection frequency higher than 80%. Except for TBP-AE and b- DBE-DBCH, non-BDEs (BFRs, CFRs and PFRs) were mainly associated with the particle phase. BDE concentrations in air were positively correlated with temperature indicating that volatilization from local sources was an important factor controlling levels in air. This correlation did not hold for most BFRs, CFRs and PFRs which were mainly on particles. For these compounds, air concentrations in Toronto are likely related to emissions from point sources and advective inputs. This study highlights the importance of urban air monitoring for FRs. Urban air can be considered a sentinel for detecting changes in the use and application of FRs in commercial products.

  3. Satellite Observations of Trace Gases and Their Application for Studying Air Quality Near Oil and Gas Operations

    NASA Astrophysics Data System (ADS)

    Kollonige, D. E.; Thompson, A. M.; Nichols, M.; Fasnacht, Z.; Martins, D. K.; Dickerson, R. R.

    2014-12-01

    The increase in the natural gas component of the energy sector has led many state and local municipalities to begin regulation of emissions from the oil and natural gas operators with air quality (AQ) as a concern. "Top-down" measurements of trace gases in the air above wells complement "bottom-up" inventories, used by EPA and AQ stakeholders, through a more accurate depiction of regional variability of methane and other species near and downwind of oil and gas operations. Satellite observations of methane, nitrogen dioxide, formaldehyde, ozone, and other carbon gases enhance the spatial and temporal coverage of the data needed to demonstrate any long-term impacts from shale gas development. As part of a NASA AQAST (Air Quality Applied Sciences Team) project, we are evaluating satellite measurements of trace gases in regions with oil and gas operations for their application as a "top-down" constraint. For validation of the satellite instruments' sensitivities to emitted gases, we focus on regions where the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) campaign deployed with ground and aircraft measurements, including, Maryland (2011), California and Texas (2013), and Colorado (2014). We compare vertical distributions of methane and volatile organic compounds (VOCs) nearby and downwind of oil and gas wells to locate any regional differences during the campaign time periods. This allows for better characterization of the satellite observations and their limitations for application in air quality studies in similar environments. Taking advantage of current EOS-era satellites' data records, we also analyze methane anomalies and gas correlations in the free troposphere from 2005 to present to identify trends for basins with oil and gas extraction sites and their influence on background concentrations downwind of wells. In most regions with oil and gas activity, we see continually

  4. Gas concentration cells for utilizing energy

    DOEpatents

    Salomon, R.E.

    1987-06-30

    An apparatus and method are disclosed for utilizing energy, in which the apparatus may be used for generating electricity or as a heat pump. When used as an electrical generator, two gas concentration cells are connected in a closed gas circuit. The first gas concentration cell is heated and generates electricity. The second gas concentration cell repressurizes the gas which travels between the cells. The electrical energy which is generated by the first cell drives the second cell as well as an electrical load. When used as a heat pump, two gas concentration cells are connected in a closed gas circuit. The first cell is supplied with electrical energy from a direct current source and releases heat. The second cell absorbs heat. The apparatus has no moving parts and thus approximates a heat engine. 4 figs.

  5. Statistics of surface divergence and their relation to air-water gas transfer velocity

    NASA Astrophysics Data System (ADS)

    Asher, William E.; Liang, Hanzhuang; Zappa, Christopher J.; Loewen, Mark R.; Mukto, Moniz A.; Litchendorf, Trina M.; Jessup, Andrew T.

    2012-05-01

    Air-sea gas fluxes are generally defined in terms of the air/water concentration difference of the gas and the gas transfer velocity,kL. Because it is difficult to measure kLin the ocean, it is often parameterized using more easily measured physical properties. Surface divergence theory suggests that infrared (IR) images of the water surface, which contain information concerning the movement of water very near the air-water interface, might be used to estimatekL. Therefore, a series of experiments testing whether IR imagery could provide a convenient means for estimating the surface divergence applicable to air-sea exchange were conducted in a synthetic jet array tank embedded in a wind tunnel. Gas transfer velocities were measured as a function of wind stress and mechanically generated turbulence; laser-induced fluorescence was used to measure the concentration of carbon dioxide in the top 300 μm of the water surface; IR imagery was used to measure the spatial and temporal distribution of the aqueous skin temperature; and particle image velocimetry was used to measure turbulence at a depth of 1 cm below the air-water interface. It is shown that an estimate of the surface divergence for both wind-shear driven turbulence and mechanically generated turbulence can be derived from the surface skin temperature. The estimates derived from the IR images are compared to velocity field divergences measured by the PIV and to independent estimates of the divergence made using the laser-induced fluorescence data. Divergence is shown to scale withkLvalues measured using gaseous tracers as predicted by conceptual models for both wind-driven and mechanically generated turbulence.

  6. On-line monitoring of benzene air concentrations while driving in traffic by means of isotopic dilution gas chromatography/mass spectrometry.

    PubMed

    Davoli, E; Cappellini, L; Moggi, M; Ferrari, S; Fanelli, R

    1996-01-01

    There is no shortage of information about the average benzene concentrations in urban air, but there is very little about microenvironmental exposure, such as in-vehicle concentrations while driving in various traffic conditions, while refuelling, or while in a parking garage. The main reason for this lack of data is that no analytical instrumentation has been available to measure on-line trace amounts of benzene in such situations. We have recently proposed a highly accurate, high-speed cryofocusing gas chromatography/mass spectrometry (GC/MS) system for monitoring benzene concentrations in air. Accuracy of the analytical data is achieved by enrichment of the air sample before trapping, with a stable isotope permeation tube system. The same principles have been applied to a new instrument, specifically designed for operation on an electric vehicle (Ducato Elettra, Fiat). The zero emission vehicle and the fully transportable, battery-operated GC/MS system provide a unique possibility of monitoring benzene exposure in real everyday situations such as while driving, refuelling, or repairing a car. All power consumptions have been reduced so as to achieve a battery-operated GC/MS system. Liquid nitrogen cryofocusing has been replaced by a packed, inductively heated, graphitized charcoal microtrap. The instrument has been mounted on shock absorbers and installed in the van. The whole system has been tested in both fixed and mobile conditions. The maximum monitoring period without external power supply is 6 h. The full analytical cycle is 4 min, allowing close to real-time monitoring, and the minimum detectable level is 1 microgram/m3 for benzene. In-vehicle monitoring showed that, when recirculation was off and ventilation on, i.e., air from outside the vehicle was blown inside, concentrations varied widely in different driving conditions: moving from a parking lot into normal traffic on an urban traffic condition roadway yielded an increase in benzene concentration

  7. Gas sensor characterization at low concentrations of natural oils

    NASA Astrophysics Data System (ADS)

    Sambemana, H.; Siadat, M.; Lumbreras, M.

    2009-05-01

    Inhalation of essential oils can be used in aromatherapy due to their activating or relaxing effects. The study of these effects requires behavioral measurements on living subjects, by varying the nature and also the quantity of the volatile substances to be present in the atmosphere. So, to permit the evaluation of therapeutic effects of a variety of natural oils, we propose to develop an automatic diffusion/detection system capable to create an ambient air with low stabilized concentration of chosen oil. In this work, we discuss the performance of an array of eight gas sensors to discriminate low and constant concentrations of a chosen natural oil.

  8. Natural gas availability and ambient air quality in the Baton Rouge/New Orleans industrial complex

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fieler, E.R.; Harrison, D.P.

    1978-02-26

    Three scenarios were modeled for the Baton Rouge/New Orleans area for 1985: one assumes the substitution of residual oil (0.7% sulfur) for gas to decrease gas-burning stationary sources from 80 to 8% and the use of properly designed stacks for large emitters; the second makes identical gas supply assumptions but adds proper stack dispersion for medium as well as large emitters; and the third is based on 16% gas-burning stationary sources. The Climatological Dispersion Model was used to translate (1974) emission rates into ambient air concentrations. Growth rates for residential, commercial, and transportation sources, but not industry, were considered. Themore » results show that proper policies, which would require not only tall stacks for large oil burning units (and for intermediate units also in the areas of high industrial concentration), but also the careful location of new plants would permit continued industrial expansion without severe air pollution problems.« less

  9. Methanethiol Concentrations and Sea-Air Fluxes in the Subarctic NE Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Kiene, R. P.; Williams, T. E.; Esson, K.; Tortell, P. D.; Dacey, J. W. H.

    2017-12-01

    Exchange of volatile organic sulfur from the ocean to the atmosphere impacts the global sulfur cycle and the climate system and is thought to occur mainly via the gas dimethylsulfide (DMS). DMS is produced during degradation of the abundant phytoplankton osmolyte dimethylsulfoniopropionate (DMSP) but bacteria can also convert dissolved DMSP into the sulfur gas methanethiol (MeSH). MeSH has been difficult to measure in seawater because of its high chemical and biological reactivity and, thus, information on MeSH concentrations, distribution and sea-air fluxes is limited. We measured MeSH in the northeast subarctic Pacific Ocean in July 2016, along transects with strong phytoplankton abundance gradients. Water samples obtained with Niskin bottles were analyzed for MeSH by purge-and-trap gas chromatography. Depth profiles showed that MeSH concentrations were high near the surface and declined with depth. Surface waters (5 m depth) had an average MeSH concentration of 0.75 nM with concentrations reaching up to 3nM. MeSH concentrations were correlated (r = 0.47) with microbial turnover of dissolved DMSP which ranged up to 236 nM per day. MeSH was also correlated with total DMSP (r = 0.93) and dissolved DMS (r = 0.63), supporting the conclusion that DMSP was a major precursor of MeSH. Surface water MeSH:DMS concentration ratios averaged 0.19 and ranged up to 0.50 indicating that MeSH was a significant fraction of the volatile sulfur pool in surface waters. Sea-air fluxes of MeSH averaged 15% of the combined DMS+MeSH flux, therefore MeSH contributed an important fraction of the sulfur emitted to the atmosphere from the subarctic NE Pacific Ocean.

  10. Rotational coherent anti-stokes Raman spectroscopy measurements in a rotating cavity with axial throughflow of cooling air: oxygen concentration measurements.

    PubMed

    Black, J D; Long, C A

    1992-07-20

    In a rotating cavity rig, which models cooling air flow in the spaces between disks of a gas turbine compressor, the buildup of oxygen concentration after the cooling gas was changed from nitrogen to air was monitored using rotational coherent anti-Stokes Raman spectroscopy (CARS). From this information an estimate of the fraction of the throughflow entering the rotating cavity was obtained. This demonstrates that rotational CARS can be applied as a nonintrusive concentration-measurement technique in a rotating engineering test rig.

  11. Air/sea DMS gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed

    NASA Astrophysics Data System (ADS)

    Bell, T. G.; De Bruyn, W.; Miller, S. D.; Ward, B.; Christensen, K.; Saltzman, E. S.

    2013-05-01

    Shipboard measurements of eddy covariance DMS air/sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. Gas transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s-1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air/sea gas flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near surface water side turbulence, and decrease interfacial gas transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air/sea exchange of DMS is controlled by interfacial rather than bubble-mediated gas transfer under high wind speed conditions.

  12. Flame holding tolerant fuel and air premixer for a gas turbine combustor

    DOEpatents

    York, William David; Johnson, Thomas Edward; Ziminsky, Willy Steve

    2012-11-20

    A fuel nozzle with active cooling is provided. It includes an outer peripheral wall, a nozzle center body concentrically disposed within the outer wall in a fuel and air pre-mixture. The fuel and air pre-mixture includes an air inlet, a fuel inlet and a premixing passage defined between the outer wall in the center body. A gas fuel flow passage is provided. A first cooling passage is included within the center body in a second cooling passage is defined between the center body and the outer wall.

  13. Impact of emissions from natural gas production facilities on ambient air quality in the Barnett Shale area: a pilot study.

    PubMed

    Zielinska, Barbara; Campbell, Dave; Samburova, Vera

    2014-12-01

    Rapid and extensive development of shale gas resources in the Barnett Shale region of Texas in recent years has created concerns about potential environmental impacts on water and air quality. The purpose of this study was to provide a better understanding of the potential contributions of emissions from gas production operations to population exposure to air toxics in the Barnett Shale region. This goal was approached using a combination of chemical characterization of the volatile organic compound (VOC) emissions from active wells, saturation monitoring for gaseous and particulate pollutants in a residential community located near active gas/oil extraction and processing facilities, source apportionment of VOCs measured in the community using the Chemical Mass Balance (CMB) receptor model, and direct measurements of the pollutant gradient downwind of a gas well with high VOC emissions. Overall, the study results indicate that air quality impacts due to individual gas wells and compressor stations are not likely to be discernible beyond a distance of approximately 100 m in the downwind direction. However, source apportionment results indicate a significant contribution to regional VOCs from gas production sources, particularly for lower-molecular-weight alkanes (< C6). Although measured ambient VOC concentrations were well below health-based safe exposure levels, the existence of urban-level mean concentrations of benzene and other mobile source air toxics combined with soot to total carbon ratios that were high for an area with little residential or commercial development may be indicative of the impact of increased heavy-duty vehicle traffic related to gas production. Implications: Rapid and extensive development of shale gas resources in recent years has created concerns about potential environmental impacts on water and air quality. This study focused on directly measuring the ambient air pollutant levels occurring at residential properties located near

  14. Methods, fluxes and sources of gas phase alkyl nitrates in the coastal air.

    PubMed

    Dirtu, Alin C; Buczyńska, Anna J; Godoi, Ana F L; Favoreto, Rodrigo; Bencs, László; Potgieter-Vermaak, Sanja S; Godoi, Ricardo H M; Van Grieken, René; Van Vaeck, Luc

    2014-10-01

    The daily and seasonal atmospheric concentrations, deposition fluxes and emission sources of a few C3-C9 gaseous alkyl nitrates (ANs) at the Belgian coast (De Haan) on the Southern North Sea were determined. An adapted sampler design for low- and high-volume air-sampling, optimized sample extraction and clean-up, as well as identification and quantification of ANs in air samples by means of gas chromatography mass spectrometry, are reported. The total concentrations of ANs ranged from 0.03 to 85 pptv and consisted primarily of the nitro-butane and nitro-pentane isomers. Air mass backward trajectories were calculated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to determine the influence of main air masses on AN levels in the air. The shorter chain ANs have been the most abundant in the Atlantic/Channel/UK air masses, while longer chain ANs prevailed in continental air. The overall mean N fluxes of the ANs were slightly higher for summer than those for winter-spring, although their contributions to the total nitrogen flux were low. High correlations between AN and HNO₂ levels were observed during winter/spring. During summer, the shorter chain ANs correlated well with precipitation. Source apportionment by means of principal component analysis indicated that most of the gas phase ANs could be attributed to traffic/combustion, secondary photochemical formation and biomass burning, although marine sources may also have been present and a contributing factor.

  15. Concentration and risk assessment of phthalates present in indoor air from newly decorated apartments

    NASA Astrophysics Data System (ADS)

    Pei, X. Q.; Song, M.; Guo, M.; Mo, F. F.; Shen, X. Y.

    2013-04-01

    Phthalate esters (PAEs) are ubiquitous in the indoor environment, owing to their use in consumer products. People spend a considerable amount of time indoors. As a result, human exposure to indoor contaminants is of great concern. People are exposed to phthalates through inhalation and dermal absorption of indoor air. In this study, the concentrations, characteristics and carcinogenic risks of gas-phase and particle-phase phthalates in indoor air from bedroom, living room and study room of 10 newly decorated apartments in Hangzhou, China were first investigated. The mean concentration of phthalates (gas-phase and particle-phase) present in household air was 12 096.4 ng m-3, of which diethyl phthalate (DEP), butylbenzyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP) were the most abundant compounds with concentrations of 2290 ng m-3, 3975 ng m-3 and 2437 ng m-3, respectively, totally accounting for 72.0% of ∑6PAEs. Contamination levels of phthalates varied in different compartments. The concentration of phthalates was the highest 17 363.7 ng m-3 in living room, followed with 11 389.5 ng m-3 in study room, and the lowest 9739.1 ng m-3 in bedroom. It was also found that phthalates mainly accumulated in gaseous form in household air. DEHP posed the greatest health risk to children aged 1-2. Carcinogenic risk of DEHP was evaluated to be 3.912 × 10-5, and was 39 times higher than the limit set by the U.S. EPA.

  16. [Concentrations and influencing factors of gaseous polycyclic aromatic hydrocarbons in residential air in Beijing].

    PubMed

    Wei, Zhi-cheng; Chang, Biao; Qiu, Wei-xun; Wang, Yi; Wu, Shi-min; Xing, Bao-shan; Liu, Wen-xin; Tao, Shu

    2007-09-01

    7 gas phase PAHs components in indoor air collected from 38 families were investigated by modified passive air samplers in Beijing areas during the local heating and non-heating seasons, and the influencing factors were discussed as well. The analytical results indicate that the gasous PAHs in local indoor air are dominated by 2 and 3 rings compounds, the mean concentrations for the 7 individual gaseous components range from 1 to 40 ng/m3, and the average concentration of total gaseous PAHs is about 100 ng/m3. There is no significant difference in total gaseous PAHs concentrations between the heating and the non-heating seasons, while some apparent seasonal changes occur in ACY and FLA concentrations. Compared with heating season, contribution of 2 rings compounds decreases while the proportions of 3 and 4 rings species increase during the non-heating season. Based on household activity questionnaires and actual analytical concentrations, the main influencing factors accounted for gaseous PAHs in indoor air, identified by multifactor analysis of variance, include cigarette smoking, use of moth ball, intensity of draft, cuisine frequency and built age.

  17. Air quality concerns of unconventional oil and natural gas production.

    PubMed

    Field, R A; Soltis, J; Murphy, S

    2014-05-01

    Increased use of hydraulic fracturing ("fracking") in unconventional oil and natural gas (O & NG) development from coal, sandstone, and shale deposits in the United States (US) has created environmental concerns over water and air quality impacts. In this perspective we focus on how the production of unconventional O & NG affects air quality. We pay particular attention to shale gas as this type of development has transformed natural gas production in the US and is set to become important in the rest of the world. A variety of potential emission sources can be spread over tens of thousands of acres of a production area and this complicates assessment of local and regional air quality impacts. We outline upstream activities including drilling, completion and production. After contrasting the context for development activities in the US and Europe we explore the use of inventories for determining air emissions. Location and scale of analysis is important, as O & NG production emissions in some US basins account for nearly 100% of the pollution burden, whereas in other basins these activities make up less than 10% of total air emissions. While emission inventories are beneficial to quantifying air emissions from a particular source category, they do have limitations when determining air quality impacts from a large area. Air monitoring is essential, not only to validate inventories, but also to measure impacts. We describe the use of measurements, including ground-based mobile monitoring, network stations, airborne, and satellite platforms for measuring air quality impacts. We identify nitrogen oxides, volatile organic compounds (VOC), ozone, hazardous air pollutants (HAP), and methane as pollutants of concern related to O & NG activities. These pollutants can contribute to air quality concerns and they may be regulated in ambient air, due to human health or climate forcing concerns. Close to well pads, emissions are concentrated and exposure to a wide range of

  18. Vertical profile of tritium concentration in air during a chronic atmospheric HT release.

    PubMed

    Noguchi, Hiroshi; Yokoyama, Sumi

    2003-03-01

    The vertical profiles of tritium gas and tritiated water concentrations in air, which would have an influence on the assessment of tritium doses as well as on the environmental monitoring of tritium, were measured in a chronic tritium gas release experiment performed in Canada in 1994. While both of the profiles were rather uniform during the day because of atmospheric mixing, large gradients of the profiles were observed at night. The gradient coefficients of the profiles were derived from the measurements. Correlations were analyzed between the gradient coefficients and meteorological conditions: solar radiation, wind speed, and turbulent diffusivity. It was found that the solar radiation was highly correlated with the gradient coefficients of tritium gas and tritiated water profiles and that the wind speed and turbulent diffusivity showed weaker correlations with those of tritiated water profiles. A one-dimensional tritium transport model was developed to analyze the vertical diffusion of tritiated water re-emitted from the ground into the atmosphere. The model consists of processes of tritium gas deposition to soil including oxidation into tritiated water, reemission of tritiated water, dilution of tritiated water in soil by rain, and vertical diffusion of tritiated water in the atmosphere. The model accurately represents the accumulation of tritiated water in soil water and the time variations and vertical profiles of tritiated water concentrations in air.

  19. Experimental study of wood downdraft gasification for an improved producer gas quality through an innovative two-stage air and premixed air/gas supply approach.

    PubMed

    Jaojaruek, Kitipong; Jarungthammachote, Sompop; Gratuito, Maria Kathrina B; Wongsuwan, Hataitep; Homhual, Suwan

    2011-04-01

    This study conducted experiments on three different downdraft gasification approaches: single stage, conventional two-stage, and an innovative two-stage air and premixed air/gas supply approach. The innovative two-stage approach has two nozzle locations, one for air supply at combustion zone and the other located at the pyrolysis zone for supplying the premixed gas (air and producer gas). The producer gas is partially bypassed to mix with air and supplied to burn at the pyrolysis zone. The result shows that producer gas quality generated by the innovative two-stage approach improved as compared to conventional two-stage. The higher heating value (HHV) increased from 5.4 to 6.5 MJ/Nm(3). Tar content in producer gas reduced to less than 45 mg/Nm(3). With this approach, gas can be fed directly to an internal combustion engine. Furthermore, the gasification thermal efficiency also improved by approximately 14%. The approach gave double benefits on gas qualities and energy savings. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Air-sea dimethylsulfide (DMS) gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed

    NASA Astrophysics Data System (ADS)

    Bell, T. G.; De Bruyn, W.; Miller, S. D.; Ward, B.; Christensen, K.; Saltzman, E. S.

    2013-11-01

    Shipboard measurements of eddy covariance dimethylsulfide (DMS) air-sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. Gas transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s-1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air-sea gas flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near-surface water-side turbulence, and decrease interfacial gas transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air-sea exchange of DMS is controlled by interfacial rather than bubble-mediated gas transfer under high wind speed conditions.

  1. Atmospheric concentrations and air–soil gas exchange of polycyclic aromatic hydrocarbons (PAHs) in remote, rural village and urban areas of Beijing–Tianjin region, North China

    PubMed Central

    Wang, Wentao; Simonich, Staci; Giri, Basant; Chang, Ying; Zhang, Yuguang; Jia, Yuling; Tao, Shu; Wang, Rong; Wang, Bin; Li, Wei; Cao, Jun; Lu, Xiaoxia

    2013-01-01

    Forty passive air samplers were deployed to study the occurrence of gas and particulate phase PAHs in remote, rural village and urban areas of Beijing–Tianjin region, North China for four seasons (spring, summer, fall and winter) from 2007 to 2008. The influence of emissions on the spatial distribution pattern of air PAH concentrations was addressed. In addition, the air–soil gas exchange of PAHs was studied using fugacity calculations. The median gaseous and particulate phase PAH concentrations were 222 ng/m3 and 114 ng/m3, respectively, with a median total PAH concentration of 349 ng/m3. Higher PAH concentrations were measured in winter than in other seasons. Air PAH concentrations measured at the rural villages and urban sites in the northern mountain region were significantly lower than those measured at sites in the southern plain during all seasons. However, there was no significant difference in PAH concentrations between the rural villages and urban sites in the northern and southern areas. This urban–rural PAH distribution pattern was related to the location of PAH emission sources and the population distribution. The location of PAH emission sources explained 56%–77% of the spatial variation in ambient air PAH concentrations. The annual median air–soil gas exchange flux of PAHs was 42.2 ng/m2/day from soil to air. Among the 15 PAHs measured, acenaphthylene (ACY) and acenaphthene (ACE) contributed to more than half of the total exchange flux. Furthermore, the air–soil gas exchange fluxes of PAHs at the urban sites were higher than those at the remote and rural sites. In summer, more gaseous PAHs volatilized from soil to air because of higher temperatures and increased rainfall. However, in winter, more gaseous PAHs deposited from air to soil due to higher PAH emissions and lower temperatures. The soil TOC concentration had no significant influence on the air–soil gas exchange of PAHs. PMID:21669328

  2. Natural ³⁷Ar concentrations in soil air: implications for monitoring underground nuclear explosions.

    PubMed

    Riedmann, Robin A; Purtschert, Roland

    2011-10-15

    For on-site inspections (OSI) under the Comprehensive Nuclear-Test-Ban Treaty (CTBT) measurement of the noble gas ³⁷Ar is considered an important technique. ³⁷Ar is produced underground by neutron activation of Calcium by the reaction ⁴⁰Ca(n,α)³⁷Ar. The naturally occurring equilibrium ³⁷Ar concentration balance in soil air is a function of an exponentially decreasing production rate from cosmic ray neutrons with increasing soil depth, diffusive transport in the soil air, and radioactive decay (T(1/2): 35 days). In this paper for the first time, measurements of natural ³⁷Ar activities in soil air are presented. The highest activities of ~100 mBq m⁻³ air are 2 orders of magnitude larger than in the atmosphere and are found in 1.5-2.5 m depth. At depths > 8 m ³⁷Ar activities are < 20 mBq m⁻³ air. After identifying the main ³⁷Ar production and gas transport factors the expected global activity range distribution of ³⁷Ar in shallow subsoil (0.7 m below the surface) was estimated. In high altitude soils, with large amounts of Calcium and with low gas permeability, ³⁷Ar activities may reach values up to 1 Bq m⁻³.

  3. An exploratory study of air emissions associated with shale gas development and production in the Barnett Shale.

    PubMed

    Rich, Alisa; Grover, James P; Sattler, Melanie L

    2014-01-01

    Information regarding air emissions from shale gas extraction and production is critically important given production is occurring in highly urbanized areas across the United States. Objectives of this exploratory study were to collect ambient air samples in residential areas within 61 m (200 feet) of shale gas extraction/production and determine whether a "fingerprint" of chemicals can be associated with shale gas activity. Statistical analyses correlating fingerprint chemicals with methane, equipment, and processes of extraction/production were performed. Ambient air sampling in residential areas of shale gas extraction and production was conducted at six counties in the Dallas/Fort Worth (DFW) Metroplex from 2008 to 2010. The 39 locations tested were identified by clients that requested monitoring. Seven sites were sampled on 2 days (typically months later in another season), and two sites were sampled on 3 days, resulting in 50 sets of monitoring data. Twenty-four-hour passive samples were collected using summa canisters. Gas chromatography/mass spectrometer analysis was used to identify organic compounds present. Methane was present in concentrations above laboratory detection limits in 49 out of 50 sampling data sets. Most of the areas investigated had atmospheric methane concentrations considerably higher than reported urban background concentrations (1.8-2.0 ppm(v)). Other chemical constituents were found to be correlated with presence of methane. A principal components analysis (PCA) identified multivariate patterns of concentrations that potentially constitute signatures of emissions from different phases of operation at natural gas sites. The first factor identified through the PCA proved most informative. Extreme negative values were strongly and statistically associated with the presence of compressors at sample sites. The seven chemicals strongly associated with this factor (o-xylene, ethylbenzene, 1,2,4-trimethylbenzene, m- and p-xylene, 1

  4. Gas sampling method for determining pollutant concentrations in the flame zone of two swirl-can combustor modules

    NASA Technical Reports Server (NTRS)

    Duerr, R. A.

    1975-01-01

    A gas sampling probe and traversing mechanism were developed to obtain detailed measurements of gaseous pollutant concentrations in the primary and mixing regions of combustors in order to better understand how pollutants are formed. The gas sampling probe was actuated by a three-degree-of-freedom traversing mechanism and the samples obtained were analyzed by an on-line gas analysis system. The pollutants in the flame zone of two different swirl-can combustor modules were measured at an inlet-air temperature of 590 K, pressure of 6 atmospheres, and reference velocities of 23 and 30 meters per second at a fuel-air ratio of 0.02. Typical results show large spatial gradients in the gaseous pollutant concentration close to the swirl-can module. Average concentrations of unburned hydrocarbons and carbon monoxide decrease rapidly in the downstream wake regions of each module. By careful and detailed probing, the effect of various module design features on pollutant formation can be assessed. The techniques presently developed seem adequate to obtain the desired information.

  5. The Effect of Rain on Air-Water Gas Exchange

    NASA Technical Reports Server (NTRS)

    Ho, David T.; Bliven, Larry F.; Wanninkhof, Rik; Schlosser, Peter

    1997-01-01

    The relationship between gas transfer velocity and rain rate was investigated at NASA's Rain-Sea Interaction Facility (RSIF) using several SF, evasion experiments. During each experiment, a water tank below the rain simulator was supersaturated with SF6, a synthetic gas, and the gas transfer velocities were calculated from the measured decrease in SF6 concentration with time. The results from experiments with IS different rain rates (7 to 10 mm/h) and 1 of 2 drop sizes (2.8 or 4.2 mm diameter) confirm a significant and systematic enhancement of air-water gas exchange by rainfall. The gas transfer velocities derived from our experiment were related to the kinetic energy flux calculated from the rain rate and drop size. The relationship obtained for mono-dropsize rain at the RSIF was extrapolated to natural rain using the kinetic energy flux of natural rain calculated from the Marshall-Palmer raindrop size distribution. Results of laboratory experiments at RSIF were compared to field observations made during a tropical rainstorm in Miami, Florida and show good agreement between laboratory and field data.

  6. Coaxial fuel and air premixer for a gas turbine combustor

    DOEpatents

    York, William D; Ziminsky, Willy S; Lacy, Benjamin P

    2013-05-21

    An air/fuel premixer comprising a peripheral wall defining a mixing chamber, a nozzle disposed at least partially within the peripheral wall comprising an outer annular wall spaced from the peripheral wall so as to define an outer air passage between the peripheral wall and the outer annular wall, an inner annular wall disposed at least partially within and spaced from the outer annular wall, so as to define an inner air passage, and at least one fuel gas annulus between the outer annular wall and the inner annular wall, the at least one fuel gas annulus defining at least one fuel gas passage, at least one air inlet for introducing air through the inner air passage and the outer air passage to the mixing chamber, and at least one fuel inlet for injecting fuel through the fuel gas passage to the mixing chamber to form an air/fuel mixture.

  7. Reducing greenhouse gas emissions and improving air quality: Two global challenges.

    PubMed

    Erickson, Larry E

    2017-07-01

    There are many good reasons to promote sustainable development and reduce greenhouse gas emissions and other combustion emissions. The air quality in many urban environments is causing many premature deaths because of asthma, cardiovascular disease, chronic obstructive pulmonary disease, lung cancer, and dementia associated with combustion emissions. The global social cost of air pollution is at least $3 trillion/year; particulates, nitrogen oxides and ozone associated with combustion emissions are very costly pollutants. Better air quality in urban environments is one of the reasons for countries to work together to reduce greenhouse gas emissions through the Paris Agreement on Climate Change. There are many potential benefits associated with limiting climate change. In the recent past, the concentrations of greenhouse gases in the atmosphere have been increasing and the number of weather and climate disasters with costs over $1 billion has been increasing. The average global temperature set new record highs in 2014, 2015, and 2016. To reduce greenhouse gas emissions, the transition to electric vehicles and electricity generation using renewable energy must take place in accord with the goals of the Paris Agreement on Climate Change. This work reviews progress and identifies some of the health benefits associated with reducing combustion emissions. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 982-988, 2017.

  8. Alternative Fuels Data Center: Natural Gas Street Sweepers Improve Air

    Science.gov Websites

    Quality in New York Natural Gas Street Sweepers Improve Air Quality in New York to someone by E -mail Share Alternative Fuels Data Center: Natural Gas Street Sweepers Improve Air Quality in New York on Facebook Tweet about Alternative Fuels Data Center: Natural Gas Street Sweepers Improve Air

  9. Oil and gas impacts on air quality in federal lands in the Bakken region: an overview of the Bakken Air Quality Study and first results

    NASA Astrophysics Data System (ADS)

    Prenni, A. J.; Day, D. E.; Evanoski-Cole, A. R.; Sive, B. C.; Hecobian, A.; Zhou, Y.; Gebhart, K. A.; Hand, J. L.; Sullivan, A. P.; Li, Y.; Schurman, M. I.; Desyaterik, Y.; Malm, W. C.; Schichtel, B. A.; Collett, J. L., Jr.

    2015-10-01

    The Bakken formation contains billions of barrels of oil and gas trapped in rock and shale. Horizontal drilling and hydraulic fracturing methods have allowed for extraction of these resources, leading to exponential growth of oil production in the region over the past decade. Along with this development has come an increase in associated emissions to the atmosphere. Concern about potential impacts of these emissions on federal lands in the region prompted the National Park Service to sponsor the Bakken Air Quality Study over two winters in 2013-2014. Here we provide an overview of the study and present some initial results aimed at better understanding the impact of local oil and gas emissions on regional air quality. Data from the study, along with long term monitoring data, suggest that while power plants are still an important emissions source in the region, emissions from oil and gas activities are impacting ambient concentrations of nitrogen oxides and black carbon and may dominate recent observed trends in pollutant concentrations at some of the study sites. Measurements of volatile organic compounds also definitively show that oil and gas emissions were present in almost every air mass sampled over a period of more than four months.

  10. Oil and gas impacts on air quality in federal lands in the Bakken region: an overview of the Bakken Air Quality Study and first results

    NASA Astrophysics Data System (ADS)

    Prenni, A. J.; Day, D. E.; Evanoski-Cole, A. R.; Sive, B. C.; Hecobian, A.; Zhou, Y.; Gebhart, K. A.; Hand, J. L.; Sullivan, A. P.; Li, Y.; Schurman, M. I.; Desyaterik, Y.; Malm, W. C.; Collett, J. L., Jr.; Schichtel, B. A.

    2016-02-01

    The Bakken formation contains billions of barrels of oil and gas trapped in rock and shale. Horizontal drilling and hydraulic fracturing methods have allowed for extraction of these resources, leading to exponential growth of oil production in the region over the past decade. Along with this development has come an increase in associated emissions to the atmosphere. Concern about potential impacts of these emissions on federal lands in the region prompted the National Park Service to sponsor the Bakken Air Quality Study over two winters in 2013-2014. Here we provide an overview of the study and present some initial results aimed at better understanding the impact of local oil and gas emissions on regional air quality. Data from the study, along with long-term monitoring data, suggest that while power plants are still an important emissions source in the region, emissions from oil and gas activities are impacting ambient concentrations of nitrogen oxides and black carbon and may dominate recent observed trends in pollutant concentrations at some of the study sites. Measurements of volatile organic compounds also definitively show that oil and gas emissions were present in almost every air mass sampled over a period of more than 4 months.

  11. Novel Apparatus for the Real-Time Quantification of Dissolved Gas Concentrations and Isotope Ratios

    NASA Astrophysics Data System (ADS)

    Gupta, M.; Leen, J.; Baer, D. S.; Owano, T. G.; Liem, J.

    2013-12-01

    Measurements of dissolved gases and their isotopic composition are critical in studying a variety of phenomena, including underwater greenhouse gas generation, air-surface exchange, and pollution migration. These studies typically involve obtaining water samples from streams, lakes, or ocean water and transporting them to a laboratory, where they are degased. The gases obtained are then generally measured using gas chromatography and isotope ratio mass spectrometry for concentrations and isotope ratios, respectively. This conventional, off-line methodology is time consuming, significantly limits the number of the samples that can be measured and thus severely inhibits detailed spatial and temporal mapping of gas concentrations and isotope ratios. In this work, we describe the development of a new membrane-based degassing device that interfaces directly to Los Gatos Research (cavity enhanced laser absorption or Off-Axis ICOS) gas analyzers (cavity enhanced laser absorption or Off-Axis ICOS analyzers) to create an autonomous system that can continuously and quickly measure concentrations and isotope ratios of dissolved gases in real time in the field. By accurately controlling the water flow rate through the membrane degasser, gas pressure on the outside of the membrane, and water pressure on the inside of the membrane, the system is able to generate precise and highly reproducible results. Moreover, by accurately measuring the gas flow rates in and out of the degasser, the gas-phase concentrations (ppm) could be converted into dissolved gas concentrations (nM). We will present detailed laboratory test data that quantifies the linearity, precision, and dynamic range of the system for the concentrations and isotope ratios of dissolved methane, carbon dioxide, and nitrous oxide. By interfacing the degassing device to a novel cavity-enhanced spectrometer (developed by LGR), preliminary data will also be presented for dissolved volatile organics (VOC) and other

  12. Measurement of air and VOC vapor fluxes during gas-driven soil remediation: bench-scale experiments.

    PubMed

    Kim, Heonki; Kim, Taeyun; Shin, Seungyeop; Annable, Michael D

    2012-09-04

    In this laboratory study, an experimental method was developed for the quantitative analyses of gas fluxes in soil during advective air flow. One-dimensional column and two- and three-dimensional flow chamber models were used in this study. For the air flux measurement, n-octane vapor was used as a tracer, and it was introduced in the air flow entering the physical models. The tracer (n-octane) in the gas effluent from the models was captured for a finite period of time using a pack of activated carbon, which then was analyzed for the mass of n-octane. The air flux was calculated based on the mass of n-octane captured by the activated carbon and the inflow concentration. The measured air fluxes are in good agreement with the actual values for one- and two-dimensional model experiments. Using both the two- and three-dimensional models, the distribution of the air flux at the soil surface was measured. The distribution of the air flux was found to be affected by the depth of the saturated zone. The flux and flux distribution of a volatile contaminant (perchloroethene) was also measured by using the two-dimensional model. Quantitative information of both air and contaminant flux may be very beneficial for analyzing the performance of gas-driven subsurface remediation processes including soil vapor extraction and air sparging.

  13. Air Impacts of Unconventional Natural Gas Development: A Barnett Shale Case Study

    NASA Astrophysics Data System (ADS)

    Moore, C. W.; Zielinska, B.; Campbell, D.; Fujita, E.

    2013-12-01

    Radiello samplers. In addition, weekly PM2.5 samples were collected on Teflon and quartz filters that were analyzed for mass and elements (Teflon filters), for organic and elemental carbon (OC and EC) by thermal/optical reflectance (TOR) method and for polycyclic aromatic hydrocarbons (PAH) using a gas chromatography/mass spectrometry (GC/MS) technique (quartz filters).VOC emissions from condensate tanks were largely low molecular weight hydrocarbons, however these tanks were enhancing local benzene concentrations mostly through malfunctioning valves. PAH concentrations were low (in pg m-3 range) but the average PAH concentration profiles (higher fraction of methylated PAHs) indicated an influence of compressor engine exhausts and increased diesel transportation traffic. These measurements, however, only represent a small 'snap-shot' of the overall emissions picture from this area. For instance during this one month study, the compressor station was predominantly downwind of the community and this may not be the case in other times of the year. Long-term study of these systems, especially in areas that have yet to experience this type of exploration, but will in the future, is needed to truly evaluate the air impacts of unconventional natural gas development.

  14. BOREAS TGB-7 Ambient Air Herbicide and Organochlorine Concentration Data

    NASA Technical Reports Server (NTRS)

    Waite, Don; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB)-7 team measured the concentration and flux of several agricultural pesticides in air, rainwater, and dry deposition samples in order to determine the associated yearly deposition rates. This data set contains information on the ambient air concentration of seven herbicides [2,4- dichlorophenoxyacidic_acid (2,4-D), bromoxynil, dicamb, 2-methyl-4-chlorophenoxyacetic acid (MCPA), triallate, trifluralin, and diclop-methyl] known to appear in the atmosphere of the Canadian prairies. Also, the concentration of three herbicides (atrazine, alachlor, and metolachlor), two groups of insecticides (lindane and breakdown products and dichloro-diphenyl-trichloroethane (DDT) and breakdown products), and several polychlorinated biphenyls commonly used in the central United States was measured. All of these chemicals are reported, in the literature, to be transported in the atmosphere. Many have been reported to occur in boreal and arctic food chains. The sampling was carried out from 16-Jun to 13-Aug-1993 and 04-May to 20-Jul-1994 at the BOREAS site in the Prince Albert National Park (Waskesiu). The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884).

  15. Air classification: Potential treatment method for optimized recycling or utilization of fine-grained air pollution control residues obtained from dry off-gas cleaning high-temperature processing systems.

    PubMed

    Lanzerstorfer, Christof

    2015-11-01

    In the dust collected from the off-gas of high-temperature processes, usually components that are volatile at the process temperature are enriched. In the recycling of the dust, the concentration of these volatile components is frequently limited to avoid operation problems. Also, for external utilization the concentration of such volatile components, especially heavy metals, is often restricted. The concentration of the volatile components is usually higher in the fine fractions of the collected dust. Therefore, air classification is a potential treatment method to deplete the coarse material from these volatile components by splitting off a fines fraction with an increased concentration of those volatile components. In this work, the procedure of a sequential classification using a laboratory air classifier and the calculations required for the evaluation of air classification for a certain application were demonstrated by taking the example of a fly ash sample from a biomass combustion plant. In the investigated example, the Pb content in the coarse fraction could be reduced to 60% by separation of 20% fines. For the non-volatile Mg the content was almost constant. It can be concluded that air classification is an appropriate method for the treatment of off-gas cleaning residues. © The Author(s) 2015.

  16. Indoor air-assessment: Indoor concentrations of environmental carcinogens

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gold, K.W.; Naugle, D.F.; Berry, M.A.

    1991-01-01

    In the report, indoor concentration data are presented for the following general categories of air pollutants: radon-222, environmental tobacco smoke (ETS), asbestos, gas phase organic compounds, formaldehyde, polycyclic aromatic hydrocarbons (PAH), pesticides, and inorganic compounds. These pollutants are either known or suspect carcinogens (i.e., radon-222, asbestos) or more complex mixtures or classes of compounds which contain known or suspect carcinogens. Concentration data for individual carcinogenic compounds in complex mixtures are usually far from complete. The data presented for complex mixtures often include compounds which are not carcinogenic or for which data are insufficient to evaluate carcinogenicity. Their inclusion is justified,more » however, by the possibility that further work may show them to be carcinogens, cocarcinogens, initiators or promotors, or that they may be employed as markers (e.g., nicotine, acrolein) for the estimation of exposure to complex mixtures.« less

  17. Modelling and analysis of ozone concentration by artificial intelligent techniques for estimating air quality

    NASA Astrophysics Data System (ADS)

    Taylan, Osman

    2017-02-01

    High ozone concentration is an important cause of air pollution mainly due to its role in the greenhouse gas emission. Ozone is produced by photochemical processes which contain nitrogen oxides and volatile organic compounds in the lower atmospheric level. Therefore, monitoring and controlling the quality of air in the urban environment is very important due to the public health care. However, air quality prediction is a highly complex and non-linear process; usually several attributes have to be considered. Artificial intelligent (AI) techniques can be employed to monitor and evaluate the ozone concentration level. The aim of this study is to develop an Adaptive Neuro-Fuzzy inference approach (ANFIS) to determine the influence of peripheral factors on air quality and pollution which is an arising problem due to ozone level in Jeddah city. The concentration of ozone level was considered as a factor to predict the Air Quality (AQ) under the atmospheric conditions. Using Air Quality Standards of Saudi Arabia, ozone concentration level was modelled by employing certain factors such as; nitrogen oxide (NOx), atmospheric pressure, temperature, and relative humidity. Hence, an ANFIS model was developed to observe the ozone concentration level and the model performance was assessed by testing data obtained from the monitoring stations established by the General Authority of Meteorology and Environment Protection of Kingdom of Saudi Arabia. The outcomes of ANFIS model were re-assessed by fuzzy quality charts using quality specification and control limits based on US-EPA air quality standards. The results of present study show that the ANFIS model is a comprehensive approach for the estimation and assessment of ozone level and is a reliable approach to produce more genuine outcomes.

  18. Amperometric Gas Sensors as a Low Cost Emerging Technology Platform for Air Quality Monitoring Applications: A Review.

    PubMed

    Baron, Ronan; Saffell, John

    2017-11-22

    This review examines the use of amperometric electrochemical gas sensors for monitoring inorganic gases that affect urban air quality. First, we consider amperometric gas sensor technology including its development toward specifically designed air quality sensors. We then review recent academic and research organizations' studies where this technology has been trialed for air quality monitoring applications: early studies showed the potential of electrochemical gas sensors when colocated with reference Air Quality Monitoring (AQM) stations. Spatially dense networks with fast temporal resolution provide information not available from sparse AQMs with longer recording intervals. We review how this technology is being offered as commercial urban air quality networks and consider the remaining challenges. Sensors must be sensitive, selective, and stable; air quality monitors/nodes must be electronically and mechanically well designed. Data correction is required and models with differing levels of sophistication are being designed. Data analysis and validation is possibly the biggest remaining hurdle needed to deliver reliable concentration readings. Finally, this review also considers the roles of companies, urban infrastructure requirements, and public research in the development of this technology.

  19. Air quality impacts of projections of natural gas-fired distributed generation

    NASA Astrophysics Data System (ADS)

    Horne, Jeremy R.; Carreras-Sospedra, Marc; Dabdub, Donald; Lemar, Paul; Nopmongcol, Uarporn; Shah, Tejas; Yarwood, Greg; Young, David; Shaw, Stephanie L.; Knipping, Eladio M.

    2017-11-01

    This study assesses the potential impacts on emissions and air quality from the increased adoption of natural gas-fired distributed generation of electricity (DG), including displacement of power from central power generation, in the contiguous United States. The study includes four major tasks: (1) modeling of distributed generation market penetration; (2) modeling of central power generation systems; (3) modeling of spatially and temporally resolved emissions; and (4) photochemical grid modeling to evaluate the potential air quality impacts of increased DG penetration, which includes both power-only DG and combined heat and power (CHP) units, for 2030. Low and high DG penetration scenarios estimate the largest penetration of future DG units in three regions - New England, New York, and California. Projections of DG penetration in the contiguous United States estimate 6.3 GW and 24 GW of market adoption in 2030 for the low DG penetration and high DG penetration scenarios, respectively. High DG penetration (all of which is natural gas-fired) serves to offset 8 GW of new natural gas combined cycle (NGCC) units, and 19 GW of solar photovoltaic (PV) installations by 2030. In all scenarios, air quality in the central United States and the northwest remains unaffected as there is little to no DG penetration in those states. California and several states in the northeast are the most impacted by emissions from DG units. Peak increases in maximum daily 8-h average ozone concentrations exceed 5 ppb, which may impede attainment of ambient air quality standards. Overall, air quality impacts from DG vary greatly based on meteorological conditions, proximity to emissions sources, the number and type of DG installations, and the emissions factors used for DG units.

  20. Combustion gas properties. 2: Natural gas fuel and dry air

    NASA Technical Reports Server (NTRS)

    Wear, J. D.; Jones, R. E.; Trout, A. M.; Mcbride, B. J.

    1985-01-01

    A series of computations has been made to produce the equilibrium temperature and gas composition for natural gas fuel and dry air. The computed tables and figures provide combustion gas property data for pressures from 0.5 to 50 atmospheres and equivalence ratios from 0 to 2.0. Only samples tables and figures are provided in this report. The complete set of tables and figures is provided on four microfiche films supplied with this report.

  1. Dry deposition and soil-air gas exchange of polychlorinated biphenyls (PCBs) in an industrial area.

    PubMed

    Bozlaker, Ayse; Odabasi, Mustafa; Muezzinoglu, Aysen

    2008-12-01

    Ambient air and dry deposition, and soil samples were collected at the Aliaga industrial site in Izmir, Turkey. Atmospheric total (particle+gas) Sigma(41)-PCB concentrations were higher in summer (3370+/-1617 pg m(-3), average+SD) than in winter (1164+/-618 pg m(-3)), probably due to increased volatilization with temperature. Average particulate Sigma(41)-PCBs dry deposition fluxes were 349+/-183 and 469+/-328 ng m(-2) day(-1) in summer and winter, respectively. Overall average particulate deposition velocity was 5.5+/-3.5 cm s(-1). The spatial distribution of Sigma(41)-PCB soil concentrations (n=48) showed that the iron-steel plants, ship dismantling facilities, refinery and petrochemicals complex are the major sources in the area. Calculated air-soil exchange fluxes indicated that the contaminated soil is a secondary source to the atmosphere for lighter PCBs and as a sink for heavier ones. Comparable magnitude of gas exchange and dry particle deposition fluxes indicated that both mechanisms are equally important for PCB movement between air and soil in Aliaga.

  2. Reducing greenhouse gas emissions and improving air quality: Two global challenges

    PubMed Central

    2017-01-01

    There are many good reasons to promote sustainable development and reduce greenhouse gas emissions and other combustion emissions. The air quality in many urban environments is causing many premature deaths because of asthma, cardiovascular disease, chronic obstructive pulmonary disease, lung cancer, and dementia associated with combustion emissions. The global social cost of air pollution is at least $3 trillion/year; particulates, nitrogen oxides and ozone associated with combustion emissions are very costly pollutants. Better air quality in urban environments is one of the reasons for countries to work together to reduce greenhouse gas emissions through the Paris Agreement on Climate Change. There are many potential benefits associated with limiting climate change. In the recent past, the concentrations of greenhouse gases in the atmosphere have been increasing and the number of weather and climate disasters with costs over $1 billion has been increasing. The average global temperature set new record highs in 2014, 2015, and 2016. To reduce greenhouse gas emissions, the transition to electric vehicles and electricity generation using renewable energy must take place in accord with the goals of the Paris Agreement on Climate Change. This work reviews progress and identifies some of the health benefits associated with reducing combustion emissions. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 982–988, 2017 PMID:29238442

  3. Air quality, primary air pollutants and ambient concentrations inventory for Romania

    NASA Astrophysics Data System (ADS)

    Năstase, Gabriel; Șerban, Alexandru; Năstase, Alina Florentina; Dragomir, George; Brezeanu, Alin Ionuț

    2018-07-01

    Air pollution is among the greatest risk factors for human health, but it also poses risks to the food security, the economy and the environment. The majority of the pollutants emitted by human activities derive from the production and use of fossil-fuel-based energy. Most energy-related emissions contain sulfur dioxide and nitrogen oxides. The principal source of sulfur dioxide originates from coal, and the main sources of nitrogen oxide emissions are power generation and use of vehicles. Other important pollutants are the inhalable coarse particles (PM10) and the fine particulate matter (PM2.5), which arises from the building sector. Over the last decade, since Romania joined the European Union on the 1st of January 2007, the use of fossil fuels has decreased dramatically, as consumers switched to either natural gas or biomass. This was as a result of the European Commission encouraging the member countries to make use of renewable sources (including biomass). To reduce the PM emissions, in April 2015 EC has extended the EcoDesign Directive to solid-fuel boilers and solid-fuel space heaters. The boilers need to generally meet certain requirements that will be introduced by 1 January 2020. In this article, we are highlighting the fluctuations in air pollution in Romania from the European WebDAB - EMAP database and trends in ambient concentrations of air pollutants using Romania's national air pollution monitoring network. Romania's Air Pollutants/Air Quality Monitoring Network consists of 142 automatic air quality monitoring stations. The results indicate that Romania's annual average mass emissions of CO decreased from 3186 Gg in 1990 to 774 in 2014 (decrease by <76%), SOx decreased from 1311 Gg-176 Gg (decrease by ∼60%), NOx decreased from 546 Gg to 218 (decrease by ∼87%), CO2 decreased from 66.226 Gg/year in 2007 to 38.916 Gg/year in 2014 (decrease by <41%).

  4. Harvesting Hydrogen Gas from Air Pollutants with an Unbiased Gas Phase Photoelectrochemical Cell.

    PubMed

    Verbruggen, Sammy W; Van Hal, Myrthe; Bosserez, Tom; Rongé, Jan; Hauchecorne, Birger; Martens, Johan A; Lenaerts, Silvia

    2017-04-10

    The concept of an all-gas-phase photoelectrochemical (PEC) cell producing hydrogen gas from volatile organic contaminated gas and light is presented. Without applying any external bias, organic contaminants are degraded and hydrogen gas is produced in separate electrode compartments. The system works most efficiently with organic pollutants in inert carrier gas. In the presence of oxygen, the cell performs less efficiently but still significant photocurrents are generated, showing the cell can be run on organic contaminated air. The purpose of this study is to demonstrate new application opportunities of PEC technology and to encourage further advancement toward PEC remediation of air pollution with the attractive feature of simultaneous energy recovery and pollution abatement. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Performance of the Proposed New Federal Reference Methods for Measuring Ozone Concentrations in Ambient Air

    EPA Science Inventory

    The current Federal Reference Method (FRM) for measuring concentrations of ozone in ambient air, described in EPA regulations at 40 CFR Part 50, Appendix D, is based on the dry, gas-phase, chemiluminescence reaction between ethylene (C2H4) and any ozone (O

  6. Analysis of problems and failures in the measurement of soil-gas radon concentration.

    PubMed

    Neznal, Martin; Neznal, Matěj

    2014-07-01

    Long-term experience in the field of soil-gas radon concentration measurements allows to describe and explain the most frequent causes of failures, which can appear in practice when various types of measurement methods and soil-gas sampling techniques are used. The concept of minimal sampling depth, which depends on the volume of the soil-gas sample and on the soil properties, is shown in detail. Consideration of minimal sampling depth at the time of measurement planning allows to avoid the most common mistakes. The ways how to identify influencing parameters, how to avoid a dilution of soil-gas samples by the atmospheric air, as well as how to recognise inappropriate sampling methods are discussed. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Correlation between concentrations of n-hexane and toluene in exhaled and environmental air in an occupationally exposed population.

    PubMed

    Periago, J F; Morente, A; Villanueva, M; Luna, A

    1994-01-01

    We determined the correlations between the concentrations of n-hexane and toluene in exhaled and environmental air in the shoe manufacturing industry. Data were collected in 1988 and in 1992 from a total of 265 subjects. Environmental air samples were collected with personal diffusive samplers by adsorption on activated charcoal during exposure and from end-expired air (alveolar air) on cartridges of activated charcoal after exposure. Both compounds were desorbed with carbon disulphide and analysed by gas chromatography. Linear regression analyses showed a good correlation between environmental and end-expired air concentrations (r = 0.82 for n-hexane and r = 0.81 for toluene). These correlations allowed us to calculate the concentrations in expired air corresponding to current environmental limit values. The calculated concentrations in end-expired air that correspond to current environmental threshold limit values of 176 mg m-3 for n-hexane and 377 mg m-3 for toluene are 28 mg m-3 (95% confidence limit, 27-29 mg m-3) and 40 mg m-3 (95% confidence limit, 39-41 mg m-3), respectively. Similar correlations were found when the data from the two study periods were analysed separately.

  8. Biologically plausible particulate air pollution mortality concentration-response functions.

    PubMed Central

    Roberts, Steven

    2004-01-01

    In this article I introduce an alternative method for estimating particulate air pollution mortality concentration-response functions. This method constrains the particulate air pollution mortality concentration-response function to be biologically plausible--that is, a non-decreasing function of the particulate air pollution concentration. Using time-series data from Cook County, Illinois, the proposed method yields more meaningful particulate air pollution mortality concentration-response function estimates with an increase in statistical accuracy. PMID:14998745

  9. Evaluation and Comparison of Chemiluminescence and UV Photometric Methods for Measuring Ozone Concentrations in Ambient Air

    EPA Science Inventory

    The current Federal Reference Method (FRM) for measuring concentrations of ozone in ambient air is based on the dry, gas-phase, chemiluminescence reaction between ethylene (C2H4) and any ozone (O3) that may be p...

  10. Determination of Fluorine in Fluoro-Organic Compounds in Low Concentrations in Air

    DTIC Science & Technology

    1944-06-27

    Analysis of 2-Fluoroethanol in Air ..... SUMMARY BIBLIOGRAPHY 15 APPENDIX , 16 FIGURE 1 Apparatus PLATE 1 CDS Scrubber SECRET ) SECRET...liter, and 68$ at 1 - 2 mg. per liter. By using two scrubbers in series, 90$ of di-isopropyl fluorophosphate was recovered at a concentration of 1 to 2...chromic acid and detection of HP by etching of the glass container ; (5) scrub- bing the gas with ammonia and decomposing the fluoro-organic compound4

  11. Reducing the oxygen concentration of gases delivered from anaesthetic machines unadapted for medical air

    PubMed Central

    Clutton, R. E.; Schoeffmann, G.; Chesnil, M.; Gregson, R.; Reed, F.; Lawson, H.; Eddleston, M.

    2014-01-01

    High fractional concentrations of inspired oxygen (FiO2) delivered over prolonged periods produce characteristic histological changes in the lungs and airway of exposed animals. Modern medical anaesthetic machines are adapted to deliver medical air (FiO2=0.21) for the purpose of reducing FiO2; anaesthetic machines designed for the veterinary market have not been so adapted. Two inexpensive modifications that allow medical air to be added to the gas flow from veterinary anaesthetic machines are described. The advantages and disadvantages of each modification are discussed. PMID:21862470

  12. The air, carbon, water synergies and trade-offs in China's natural gas industry

    NASA Astrophysics Data System (ADS)

    Qin, Y.; Mauzerall, D. L.; Höglund-Isaksson, L.; Wagner, F.; Byers, E.

    2017-12-01

    Both energy production and consumption can simultaneously affect regional air quality, local water stress, and the global climate. Identifying air, carbon and water impacts of various energy sources and end-uses is important in determining the relative merits of various energy policies. Here, we examine the air-carbon-water interdependencies of China's six major natural gas source choices (domestic conventional natural gas, domestic coal-based synthetic natural gas (SNG), domestic shale gas, imported liquefied natural gas, imported Russian pipeline gas, and imported Central Asian pipeline gas) and three end-use coal-to-gas deployment strategies (with substitution strategies that focus in turn on air quality, carbon, and water) in 2020. On the supply side, we find that gas sources other than SNG offer national air-carbon-water co-benefits. However, we find striking air-carbon/water trade-offs for SNG at the national scale. Moreover, the use of SNG significantly increases water demand and carbon emissions in regions already suffering from the most severe water stress and the highest per capita carbon footprint. On the end-use side, gas substitution for coal can result in enormous variations in air quality, carbon, and water impacts, with notable air-carbon synergies but air-water trade-offs. Our study finds that, except for SNG, end-use choices generally have a much larger influence on air quality, carbon emissions and water use than do gas source choices. Simultaneous consideration of air, carbon, and water impacts is necessary in designing both beneficial energy development and deployment policies.

  13. Evaluation of the Community Multiscale Air Quality Model for Simulating Winter Ozone Formation in the Uinta Basin with Intensive Oil and Gas Production

    NASA Astrophysics Data System (ADS)

    Matichuk, R.; Tonnesen, G.; Luecken, D.; Roselle, S. J.; Napelenok, S. L.; Baker, K. R.; Gilliam, R. C.; Misenis, C.; Murphy, B.; Schwede, D. B.

    2015-12-01

    The western United States is an important source of domestic energy resources. One of the primary environmental impacts associated with oil and natural gas production is related to air emission releases of a number of air pollutants. Some of these pollutants are important precursors to the formation of ground-level ozone. To better understand ozone impacts and other air quality issues, photochemical air quality models are used to simulate the changes in pollutant concentrations in the atmosphere on local, regional, and national spatial scales. These models are important for air quality management because they assist in identifying source contributions to air quality problems and designing effective strategies to reduce harmful air pollutants. The success of predicting oil and natural gas air quality impacts depends on the accuracy of the input information, including emissions inventories, meteorological information, and boundary conditions. The treatment of chemical and physical processes within these models is equally important. However, given the limited amount of data collected for oil and natural gas production emissions in the past and the complex terrain and meteorological conditions in western states, the ability of these models to accurately predict pollution concentrations from these sources is uncertain. Therefore, this presentation will focus on understanding the Community Multiscale Air Quality (CMAQ) model's ability to predict air quality impacts associated with oil and natural gas production and its sensitivity to input uncertainties. The results will focus on winter ozone issues in the Uinta Basin, Utah and identify the factors contributing to model performance issues. The results of this study will help support future air quality model development, policy and regulatory decisions for the oil and gas sector.

  14. Confirmation of the sterilization effect using a high concentration of ozone gas for the bio-clean room.

    PubMed

    Iwamura, Takuji; Nagano, Katsunori; Nogami, Toshihiro; Matsuki, Noritomo; Kosaka, Noriyoshi; Shintani, Hideharu; Katoh, Miyoshi

    2013-01-01

    A high-level aseptic environment must be maintained in bio-cleanrooms used for the manufacture of sterile products. In the past, formaldehyde gas was most commonly used to sterilize bio-cleanrooms, but due to strict residual limitations there has been a need to develop a less toxic alternative choice. The authors have developed a revolutionary new sterilization system using a high concentration of ozone gas and used this system to sterilize an actual bio-cleanroom. This system integrates the ozone gas generator with the air conditioning system by proper control. The design specifications for the system included an ozone gas concentration of 200 ppm or more, relative humidity of 80% or more, and a sterilizing time of 120 min. Blow vents and suction ports were placed to ensure a uniform airflow which would extend through the entire room during ozone gas sterilization. Tests regarding long-term material exposure to ozone gas were conducted when the system was introduced to distinguish usable and unusable materials. In an actually constructed cleanroom, simulations were used to predict the evenness of the diffusion of ozone gas concentration and relative humidity during ozone gas sterilization, and measurements of the actual indoor ozone gas concentration, temperature and relative humidity during sterilization revealed that the ozone concentration and relative humidity needed for sterilization had been achieved generally throughout the entire environment. In addition, the CT value (mg/m(3) (=ppm) × min) , derived by multiplying the ozone gas concentration during ozone gas sterilization by the sterilization time, was equal to or greater than the target value of 24 × 10(3) (ppm·min) . When the results of sterilization in a cleanroom were confirmed using a biological indicator (BI) , negative results were obtained at all measurement points, demonstrating that sterilization was being performed effectively in the actual factory at which the ozone gas sterilization system

  15. Advances in quantifying air-sea gas exchange and environmental forcing.

    PubMed

    Wanninkhof, Rik; Asher, William E; Ho, David T; Sweeney, Colm; McGillis, Wade R

    2009-01-01

    The past decade has seen a substantial amount of research on air-sea gas exchange and its environmental controls. These studies have significantly advanced the understanding of processes that control gas transfer, led to higher quality field measurements, and improved estimates of the flux of climate-relevant gases between the ocean and atmosphere. This review discusses the fundamental principles of air-sea gas transfer and recent developments in gas transfer theory, parameterizations, and measurement techniques in the context of the exchange of carbon dioxide. However, much of this discussion is applicable to any sparingly soluble, non-reactive gas. We show how the use of global variables of environmental forcing that have recently become available and gas exchange relationships that incorporate the main forcing factors will lead to improved estimates of global and regional air-sea gas fluxes based on better fundamental physical, chemical, and biological foundations.

  16. Research on inert gas narcosis and air velocity effects on metabolic performance

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The effects of air velocity on metabolic performance are studied by using high forced airflow in a closed environment as a mechanism to control the concentration of volatile animal wastes. Air velocities between 100 and 200 ft/min are without significant effects on the metabolism of rats. At velocities of 200 ft/min and above, oxygen consumption and CO2 production as well as food consumption increase. In most instances, the changes are on the order of 5-10%. At the same time, the RQ for the animals increases slightly and generally correlates well with oxygen consumption and CO2 production. Experiments on the nature of inert gas narcosis show that halothane and methoxyflurane are rather potent inhibitors of the NADH:O2 oxidoreductase system in rats. These experiments suggest that the mechanism of inert gas narcosis is not mandatorily related to a membrane surface phenomenon.

  17. Daily variation of radon gas and its short-lived progeny concentration near ground level and estimation of aerosol residence time

    NASA Astrophysics Data System (ADS)

    M, Mohery; A, M. Abdallah; A, Ali; S, S. Baz

    2016-05-01

    Atmospheric concentrations of radon (222Rn) gas and its short-lived progenies 218Po, 214Pb, and 214Po were continuously monitored every four hours at the ground level in Jeddah city, Kingdom of Saudi Arabia. The measurements were performed three times every week, starting from November 2014 to October 2015. A method of electrostatic precipitation of positively charged 218Po and 214Po by a positive voltage was applied for determining 222Rn gas concentration. The short-lived 222Rn progeny concentration was determined by using a filter holder connected with the alpha-spectrometric technique. The meteorological parameters (relative air humidity, air temperature, and wind speed) were determined during the measurements of 222Rn and its progeny concentrations. 222Rn gas as well as its short-lived progeny concentration display a daily and seasonal variation with high values in the night and early morning hours as compared to low values at noon and in the afternoon. The observed monthly atmospheric concentrations showed a seasonal trend with the highest values in the autumn/winter season and the lowest values in the spring/summer season. Moreover, and in parallel with alpha-spectrometric measurements, a single filter-holder was used to collect air samples. The deposited activities of 214Pb and the long-lived 222Rn daughter 210Pb on the filter were measured with the gamma spectrometric technique. The measured activity concentrations of 214Pb by both techniques were found to be relatively equal largely. The highest mean seasonally activity concentrations of 210Pb were observed in the autumn/winter season while the lowest mean were observed in the spring/summer season. The mean residence time (MRT) of aerosol particles in the atmospheric air could be estimated from the activity ratios of 210Pb/214Pb. Project supported by the Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah (Grant No. 291/965/1434).

  18. Air Contamination Quantification by FTIR with Gas Cell

    NASA Technical Reports Server (NTRS)

    Freischlag, Jason

    2017-01-01

    Air quality is of utmost importance in environmental studies and has many industrial applications such as aviators grade breathing oxygen (ABO) for pilots and breathing air for fire fighters. Contamination is a major concern for these industries as identified in MIL-PRF-27210, CGA G-4.3, CGA G-7.1, and NFPA 1989. Fourier Transform Infrared Spectroscopy (FTIR) is a powerful tool that when combined with a gas cell has tremendous potential for gas contamination analysis. Current procedures focus mostly on GC-MS for contamination quantification. Introduction of this topic will be done through a comparison of the currently used deterministic methods for gas contamination with those of FTIR gas analysis. Certification of the mentioned standards through the ISOIEC 17065 certifying body A2LA will be addressed followed by an evaluation of quality information such as the determinations of linearity and the limits of detection and quantitation. Major interferences and issues arising from the use of the FTIR for accredited work with ABO and breathing air will be covered.

  19. A new air quality monitoring and early warning system: Air quality assessment and air pollutant concentration prediction.

    PubMed

    Yang, Zhongshan; Wang, Jian

    2017-10-01

    Air pollution in many countries is worsening with industrialization and urbanization, resulting in climate change and affecting people's health, thus, making the work of policymakers more difficult. It is therefore both urgent and necessary to establish amore scientific air quality monitoring and early warning system to evaluate the degree of air pollution objectively, and predict pollutant concentrations accurately. However, the integration of air quality assessment and air pollutant concentration prediction to establish an air quality system is not common. In this paper, we propose a new air quality monitoring and early warning system, including an assessment module and forecasting module. In the air quality assessment module, fuzzy comprehensive evaluation is used to determine the main pollutants and evaluate the degree of air pollution more scientifically. In the air pollutant concentration prediction module, a novel hybridization model combining complementary ensemble empirical mode decomposition, a modified cuckoo search and differential evolution algorithm, and an Elman neural network, is proposed to improve the forecasting accuracy of six main air pollutant concentrations. To verify the effectiveness of this system, pollutant data for two cities in China are used. The result of the fuzzy comprehensive evaluation shows that the major air pollutants in Xi'an and Jinan are PM 10 and PM 2.5 respectively, and that the air quality of Xi'an is better than that of Jinan. The forecasting results indicate that the proposed hybrid model is remarkably superior to all benchmark models on account of its higher prediction accuracy and stability. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Air impacts of increased natural gas acquisition, processing, and use: a critical review.

    PubMed

    Moore, Christopher W; Zielinska, Barbara; Pétron, Gabrielle; Jackson, Robert B

    2014-01-01

    During the past decade, technological advancements in the United States and Canada have led to rapid and intensive development of many unconventional natural gas plays (e.g., shale gas, tight sand gas, coal-bed methane), raising concerns about environmental impacts. Here, we summarize the current understanding of local and regional air quality impacts of natural gas extraction, production, and use. Air emissions from the natural gas life cycle include greenhouse gases, ozone precursors (volatile organic compounds and nitrogen oxides), air toxics, and particulates. National and state regulators primarily use generic emission inventories to assess the climate, air quality, and health impacts of natural gas systems. These inventories rely on limited, incomplete, and sometimes outdated emission factors and activity data, based on few measurements. We discuss case studies for specific air impacts grouped by natural gas life cycle segment, summarize the potential benefits of using natural gas over other fossil fuels, and examine national and state emission regulations pertaining to natural gas systems. Finally, we highlight specific gaps in scientific knowledge and suggest that substantial additional measurements of air emissions from the natural gas life cycle are essential to understanding the impacts and benefits of this resource.

  1. Modeling of Hydrate Formation Mode in Raw Natural Gas Air Coolers

    NASA Astrophysics Data System (ADS)

    Scherbinin, S. V.; Prakhova, M. Yu; Krasnov, A. N.; Khoroshavina, E. A.

    2018-05-01

    Air cooling units (ACU) are used at all the gas fields for cooling natural gas after compressing. When using ACUs on raw (wet) gas in a low temperature condition, there is a danger of hydrate plug formation in the heat exchanging tubes of the ACU. To predict possible hydrate formation, a mathematical model of the air cooler thermal behavior used in the control system shall adequately calculate not only gas temperature at the cooler's outlet, but also a dew point value, a temperature at which condensation, as well as the gas hydrate formation point, onsets. This paper proposes a mathematical model allowing one to determine the pressure in the air cooler which makes hydrate formation for a given gas composition possible.

  2. The potential role of sea spray droplets in facilitating air-sea gas transfer

    NASA Astrophysics Data System (ADS)

    Andreas, E. L.; Vlahos, P.; Monahan, E. C.

    2016-05-01

    For over 30 years, air-sea interaction specialists have been evaluating and parameterizing the role of whitecap bubbles in air-sea gas exchange. To our knowledge, no one, however, has studied the mirror image process of whether sea spray droplets can facilitate air-sea gas exchange. We are therefore using theory, data analysis, and numerical modeling to quantify the role of spray on air-sea gas transfer. In this, our first formal work on this subject, we seek the rate-limiting step in spray-mediated gas transfer by evaluating the three time scales that govern the exchange: τ air , which quantifies the rate of transfer between the atmospheric gas reservoir and the surface of the droplet; τ int , which quantifies the exchange rate across the air-droplet interface; and τ aq , which quantifies gas mixing within the aqueous solution droplet.

  3. Wintertime Air-Sea Gas Transfer Rates and Air Injection Fluxes at Station Papa in the NE Pacific

    NASA Astrophysics Data System (ADS)

    McNeil, C.; Steiner, N.; Vagle, S.

    2008-12-01

    In recent studies of air-sea fluxes of N2 and O2 in hurricanes, McNeil and D'Asaro (2007) used a simplified model formulation of air-sea gas flux to estimate simultaneous values of gas transfer rate, KT, and air injection flux, VT. The model assumes air-sea gas fluxes at high to extreme wind speeds can be explained by a combination of two processes: 1) air injection, by complete dissolution of small bubbles drawn down into the ocean boundary layer by turbulent currents, and 2) near-surface equilibration processes, such as occurs within whitecaps. This analysis technique relies on air-sea gas flux estimates for two gases, N2 and O2, to solve for the two model parameters, KT and VT. We present preliminary results of similar analysis of time series data collected during winter storms at Station Papa in the NE Pacific during 2003/2004. The data show a clear increase in KT and VT with increasing NCEP derived wind speeds and acoustically measured bubble penetration depth.

  4. [Calibration of a room air gas monitor with certified reference gases].

    PubMed

    Krueger, W A; Trick, M; Schroeder, T H; Unertl, K E

    2003-12-01

    Photo-acoustic infrared spectrometry is considered to be the gold standard for on-line measurement of anesthetic waste gas in room air. For maintenance of the precision of the measurements, the manufacturer recommends calibration of the gas monitor monitor every 3-12 months. We investigated whether the use of reference gases with analysis certificate could serve as a feasible alternative to commercial recalibration. We connected a multi-gas monitor type1302 (Bruel & Kjaer, Naerum, Denmark) to compressed air bottles containing reference gases with analysis certificate. Using a T-piece with a flow-meter, we avoided the entry of room air during the calibration phase. Highly purified nitrogen was used for zero calibration. The reference concentrations for desflurane, enflurane, halothane, isoflurane, and sevoflurane ranged from 41.6-51.1 ml/m(3) (ppm) in synthetic air. Since there is an overlap of the infrared absorption spectra of volatile anesthetics with alcohol used in operating rooms, we performed a cross-compensation with iso-propanol (107.0 ppm). A two-point calibration was performed for N(2)O (96.2 and 979.0 ppm), followed by cross-compensation with CO(2). Nafion tubes were used in order to avoid erroneous measurements due to molecular relaxation phenomena. The deviation of the measurement values ranged initially from 0-2.0% and increased to up to 4.9% after 18 months. For N(2)O, the corresponding values were 4.2% and 2.7%, respectively. Thus, our calibration procedure using certified reference gases yielded precise measurements with low deterioration over 18 months. It seems to be advantageous that the precision can be determined whenever deemed necessary. This allows for an individual decision, when the gas monitor needs to be calibrated again. The costs for reference gases and working time as well as logistic aspects such as storage and expiration dates must be individually balanced against the costs for commercial recalibration.

  5. Air radon concentration decrease in a waste water treatment plant.

    PubMed

    Juste, B; Ortiz, J; Verdú, G; Martorell, S

    2015-06-01

    (222)Rn is a naturally occurring gas created from the decay of (226)Ra. The long-term health risk of breathing radon is lung cancer. One particular place where indoor radon concentrations can exceed national guidelines is in wastewater treatment plants (WWTPs) where treatment processes may contribute to ambient airborne concentrations. The aim of this paper was to study the radon concentration decrease after the application of corrective measures in a Spanish WWTP. According to first measures, air radon concentration exceeded International Commission Radiologica1 Protection (ICRP) normative (recommends intervention between 400 and 1000 Bq m(-3)). Therefore, the WWTP improved mechanical forced ventilation to lower occupational exposure. This measure allowed to increase the administrative controls, since the limitation of workers access to the plant changed from 2 h d(-1) (considering a maximum permissible dose of 20 mSv y(-1) averaged over 5 y) to 7 h d(-1). © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. Long-term stability measurements of low concentration Volatile Organic Compound gas mixtures

    NASA Astrophysics Data System (ADS)

    Allen, Nick; Amico di Meane, Elena; Brewer, Paul; Ferracci, Valerio; Corbel, Marivon; Worton, David

    2017-04-01

    VOCs (Volatile Organic Compounds) are a class of compounds with significant influence on the atmosphere due to their large anthropogenic and biogenic emission sources. VOC emissions have a significant impact on the atmospheric hydroxyl budget and nitrogen reservoir species, while also contributing indirectly to the production of tropospheric ozone and secondary organic aerosol. However, the global budget of many of these species are poorly constrained. Moreover, the World Meteorological Organization's (WMO) Global Atmosphere Watch (GAW) have set challenging data quality objectives for atmospheric monitoring programmes for these classes of traceable VOCs, despite the lack of available stable gas standards. The Key-VOCs Joint Research Project is an ongoing three-year collaboration with the aim of improving the measurement infrastructure of important atmospheric VOCs by providing traceable and comparable reference gas standards and by validating new measurement systems in support of the air monitoring networks. It focuses on VOC compounds that are regulated by European legislation, that are relevant for indoor air monitoring and for air quality and climate monitoring programmes like the VOC programme established by the WMO GAW and the European Monitoring and Evaluation Programme (EMEP). These VOCs include formaldehyde, oxy[genated]-VOCs (acetone, ethanol and methanol) and terpenes (a-pinene, 1,8-cineole, δ-3-carene and R-limonene). Here we present the results of a novel long term stability study for low concentration formaldehyde, oxy-VOC and terpenes gas mixtures produced by the Key-VOCs consortium with discussion regarding the implementation of improved preparation techniques and the use of novel cylinder passivation chemistries to guarantee mixture stability.

  7. Measuring Concentrations of Particulate 140La in the Air

    DOE PAGES

    Okada, Colin E.; Kernan, Warnick J.; Keillor, Martin E.; ...

    2016-05-01

    Air sampling systems were deployed to measure the concentration of radioactive material in the air during the Full-Scale Radiological Dispersal Device experiments. The air samplers were positioned 100-600 meters downwind of the release point. The filters were collected immediately and analyzed in the field. Quantities for total activity collected on the air filters are reported along with additional information to compute the average or integrated air concentrations.

  8. Indoor air pollution from gas cooking and infant neurodevelopment.

    PubMed

    Vrijheid, Martine; Martinez, David; Aguilera, Inma; Bustamante, Mariona; Ballester, Ferran; Estarlich, Marisa; Fernandez-Somoano, Ana; Guxens, Mònica; Lertxundi, Nerea; Martinez, M Dolores; Tardon, Adonina; Sunyer, Jordi

    2012-01-01

    Gas cooking is a main source of indoor air pollutants, including nitrogen dioxide and particles. Because concerns are emerging for neurodevelopmental effects of air pollutants, we examined the relationship between indoor gas cooking during pregnancy and infant neurodevelopment. Pregnant mothers were recruited between 2004 and 2008 to a prospective birth cohort study (INfancia y Medio Ambiente) in Spain during the first trimester of pregnancy. Third-trimester questionnaires collected information about the use of gas appliances at home. At age 11 to 22 months, children were assessed for mental development using the Bayley Scales of Infant Development. Linear regression models examined the association of gas cooking and standardized mental development scores (n = 1887 mother-child pairs). Gas cookers were present in 44% of homes. Gas cooking was related to a small decrease in the mental development score compared with use of other cookers (-2.5 points [95% confidence interval = -4.0 to -0.9]) independent of social class, maternal education, and other measured potential confounders. This decrease was strongest in children tested after the age of 14 months (-3.1 points [-5.1 to -1.1]) and when gas cooking was combined with less frequent use of an extractor fan. The negative association with gas cooking was relatively consistent across strata defined by social class, education, and other covariates. This study suggests a small adverse effect of indoor air pollution from gas cookers on the mental development of young children.

  9. Silica Gel Coated Spherical Micro resonator for Ultra-High Sensitivity Detection of Ammonia Gas Concentration in Air.

    PubMed

    Mallik, Arun Kumar; Farrell, Gerald; Liu, Dejun; Kavungal, Vishnu; Wu, Qiang; Semenova, Yuliya

    2018-01-26

    A silica gel coated microsphere resonator is proposed and experimentally demonstrated for measurements of ammonia (NH 3 ) concentration in air with ultra-high sensitivity. The optical properties of the porous silica gel layer change when it is exposed to low (parts per million (ppm)) and even ultra-low (parts per billion (ppb)) concentrations of ammonia vapor, leading to a spectral shift of the WGM resonances in the transmission spectrum of the fiber taper. The experimentally demonstrated sensitivity of the proposed sensor to ammonia is estimated as 34.46 pm/ppm in the low ammonia concentrations range from 4 ppm to 30 ppm using an optical spectrum analyser (OSA), and as 800 pm/ppm in the ultra-low range of ammonia concentrations from 2.5 ppb to 12 ppb using the frequency detuning method, resulting in the lowest detection limit (by two orders of magnitude) reported to date equal to 0.16 ppb of ammonia in air. In addition, the sensor exhibits excellent selectivity to ammonia and very fast response and recovery times measured at 1.5 and 3.6 seconds, respectively. Other attractive features of the proposed sensor are its compact nature, simplicity of fabrication.

  10. Analysis of concentration fluctuations in gas dispersion around high-rise building for different incident wind directions.

    PubMed

    Liu, X P; Niu, J L; Kwok, K C S

    2011-09-15

    This article presents experimental results that illustrate the unsteady characteristics of gas dispersion around a complex-shaped high-rise building for different incident wind directions. A series of wind tunnel experiments were conducted using a 1:30 scale model that represented the real structures under study. The objective of this paper is to study the behaviour of concentration fluctuations through transient analysis. Tracer gas was continuously released from a point source located at different positions, and a time series of fluctuating concentrations were recorded at a large number of points using fast flame ionization detectors. The experimental data were analysed to provide a comprehensive data set including variances and associated statistical quantities. Both the unsteady characteristics of the system and their potential practical impact are presented and discussed. Under crowd living conditions, the air pollutant exhausted from one household could probably re-enter into the neighbouring households, traveling with ambient airflow. Such pollutant dispersion process is defined as air cross-contamination in this study. The results indicate that the wind-induced cross-contamination around the studied type of high-rise building should not be overlooked, and the fluctuating concentrations should be paid attention to particularly during the evaluation of a potential contamination risk. This study can help deepen our understanding of the mechanisms of air cross-contamination, and will be useful for implementing optimization strategies to improve the built environments in metropolitan cities such as Hong Kong. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Modeling of Thermal Behavior of Raw Natural Gas Air Coolers

    NASA Astrophysics Data System (ADS)

    Scherbinin, S. V.; Prakhova, M. Yu; Krasnov, A. N.; Khoroshavina, E. A.

    2018-05-01

    When gas is being prepared for a long-range transportation, it passes through air cooling units (ACUs) after compressing; there, hot gas passing through finned tubes is cooled with air streams. ACU's mode of operation shall ensure a certain value of gas temperature at the ACU's outlet. At that, when cooling raw gas, temperature distribution along all the tubes shall be known to prevent local hydrate formation. The paper proposes a mathematical model allowing one to obtain a thermal field distribution inside the ACU and study influence of various factors onto it.

  12. Real-Time Optical Fuel-to-Air Ratio Sensor for Gas Turbine Combustors

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet; Mongia, Rajiv K.; Dibble, Robert W.

    1999-01-01

    The measurement of the temporal distribution of fuel in gas turbine combustors is important in considering pollution, combustion efficiency and combustor dynamics and acoustics. Much of the previous work in measuring fuel distributions in gas turbine combustors has focused on the spatial aspect of the distribution. The temporal aspect however, has often been overlooked, even though it is just as important. In part, this is due to the challenges of applying real-time diagnostic techniques in a high pressure and high temperature environment. A simple and low-cost instrument that non-intrusively measures the real-time fuel-to-air ratio (FAR) in a gas turbine combustor has been developed. The device uses a dual wavelength laser absorption technique to measure the concentration of most hydrocarbon fuels such as jet fuel, methane, propane, etc. The device can be configured to use fiber optics to measure the local FAR inside a high pressure test rig without the need for windows. Alternatively, the device can readily be used in test rigs that have existing windows without modifications. An initial application of this instrument was to obtain time-resolved measurements of the FAR in the premixer of a lean premixed prevaporized (LPP) combustor at inlet air pressures and temperatures as high as 17 atm at 800 K, with liquid JP-8 as the fuel. Results will be presented that quantitatively show the transient nature of the local FAR inside a LPP gas turbine combustor at actual operating conditions. The high speed (kHz) time resolution of this device, combined with a rugged fiber optic delivery system, should enable the realization of a flight capable active-feedback and control system for the abatement of noise and pollutant emissions in the future. Other applications that require an in-situ and time-resolved measurement of fuel vapor concentrations should also find this device to be of use.

  13. Design of 50MM Powder to Air to Light Gas Gun Converter

    DTIC Science & Technology

    2008-06-01

    AFRL-RW-EG-TR-2008-7088 Design of 50MM Powder to Air or Light Gas Gun Converter Justin Chiasson, Matthew Hohenshutz, Jason Picone and Daniel...Final (September 2007-May 2008 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER 5b. GRANT NUMBER DESIGN OF 50MM POWDER TO AIR OR LIGHT GAS GUN CONVERTER...objectives and progress of the air gun project. The main objective is to design an air or light gas gun to launch a 1 kg projectile up to 2000 ft/s. An

  14. Reconstruction of combustion temperature and gas concentration distributions using line-of-sight tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Zhirong; Sun, Pengshuai; Pang, Tao; Xia, Hua; Cui, Xiaojuan; Li, Zhe; Han, Luo; Wu, Bian; Wang, Yu; Sigrist, Markus W.; Dong, Fengzhong

    2016-07-01

    Spatial temperature and gas concentration distributions are crucial for combustion studies to characterize the combustion position and to evaluate the combustion regime and the released heat quantity. Optical computer tomography (CT) enables the reconstruction of temperature and gas concentration fields in a flame on the basis of line-of-sight tunable diode laser absorption spectroscopy (LOS-TDLAS). A pair of H2O absorption lines at wavelengths 1395.51 and 1395.69 nm is selected. Temperature and H2O concentration distributions for a flat flame furnace are calculated by superimposing two absorption peaks with a discrete algebraic iterative algorithm and a mathematical fitting algorithm. By comparison, direct absorption spectroscopy measurements agree well with the thermocouple measurements and yield a good correlation. The CT reconstruction data of different air-to-fuel ratio combustion conditions (incomplete combustion and full combustion) and three different types of burners (one, two, and three flat flame furnaces) demonstrate that TDLAS has the potential of short response time and enables real-time temperature and gas concentration distribution measurements for combustion diagnosis.

  15. On the role of sea-state in bubble-mediated air-sea gas flux during a winter storm

    NASA Astrophysics Data System (ADS)

    Liang, Jun-Hong; Emerson, Steven R.; D'Asaro, Eric A.; McNeil, Craig L.; Harcourt, Ramsey R.; Sullivan, Peter P.; Yang, Bo; Cronin, Meghan F.

    2017-04-01

    Oceanic bubbles play an important role in the air-sea exchange of weakly soluble gases at moderate to high wind speeds. A Lagrangian bubble model embedded in a large eddy simulation model is developed to study bubbles and their influence on dissolved gases in the upper ocean. The transient evolution of mixed-layer dissolved oxygen and nitrogen gases at Ocean Station Papa (50°N, 145°W) during a winter storm is reproduced with the model. Among different physical processes, gas bubbles are the most important in elevating dissolved gas concentrations during the storm, while atmospheric pressure governs the variability of gas saturation anomaly (the relative departure of dissolved gas concentration from the saturation concentration). For the same wind speed, bubble-mediated gas fluxes are larger during rising wind with smaller wave age than during falling wind with larger wave age. Wave conditions are the primary cause for the bubble gas flux difference: when wind strengthens, waves are less-developed with respect to wind, resulting in more frequent large breaking waves. Bubble generation in large breaking waves is favorable for a large bubble-mediated gas flux. The wave-age dependence is not included in any existing bubble-mediated gas flux parameterizations.

  16. Ozone concentrations and damage for realistic future European climate and air quality scenarios

    NASA Astrophysics Data System (ADS)

    Hendriks, Carlijn; Forsell, Nicklas; Kiesewetter, Gregor; Schaap, Martijn; Schöpp, Wolfgang

    2016-11-01

    Ground level ozone poses a significant threat to human health from air pollution in the European Union. While anthropogenic emissions of precursor substances (NOx, NMVOC, CH4) are regulated by EU air quality legislation and will decrease further in the future, the emissions of biogenic NMVOC (mainly isoprene) may increase significantly in the coming decades if short-rotation coppice plantations are expanded strongly to meet the increased biofuel demand resulting from the EU decarbonisation targets. This study investigates the competing effects of anticipated trends in land use change, anthropogenic ozone precursor emissions and climate change on European ground level ozone concentrations and related health and environmental impacts until 2050. The work is based on a consistent set of energy consumption scenarios that underlie current EU climate and air quality policy proposals: a current legislation case, and an ambitious decarbonisation case. The Greenhouse Gas-Air Pollution Interactions and Synergies (GAINS) integrated assessment model was used to calculate air pollutant emissions for these scenarios, while land use change because of bioenergy demand was calculated by the Global Biosphere Model (GLOBIOM). These datasets were fed into the chemistry transport model LOTOS-EUROS to calculate the impact on ground level ozone concentrations. Health damage because of high ground level ozone concentrations is projected to decline significantly towards 2030 and 2050 under current climate conditions for both energy scenarios. Damage to plants is also expected to decrease but to a smaller extent. The projected change in anthropogenic ozone precursor emissions is found to have a larger impact on ozone damage than land use change. The increasing effect of a warming climate (+2-5 °C across Europe in summer) on ozone concentrations and associated health damage, however, might be higher than the reduction achieved by cutting back European ozone precursor emissions. Global

  17. Estimation of uncertainty in tracer gas measurement of air change rates.

    PubMed

    Iizuka, Atsushi; Okuizumi, Yumiko; Yanagisawa, Yukio

    2010-12-01

    Simple and economical measurement of air change rates can be achieved with a passive-type tracer gas doser and sampler. However, this is made more complex by the fact many buildings are not a single fully mixed zone. This means many measurements are required to obtain information on ventilation conditions. In this study, we evaluated the uncertainty of tracer gas measurement of air change rate in n completely mixed zones. A single measurement with one tracer gas could be used to simply estimate the air change rate when n = 2. Accurate air change rates could not be obtained for n ≥ 2 due to a lack of information. However, the proposed method can be used to estimate an air change rate with an accuracy of <33%. Using this method, overestimation of air change rate can be avoided. The proposed estimation method will be useful in practical ventilation measurements.

  18. Atmospheric emissions and air quality impacts from natural gas production and use.

    PubMed

    Allen, David T

    2014-01-01

    The US Energy Information Administration projects that hydraulic fracturing of shale formations will become a dominant source of domestic natural gas supply over the next several decades, transforming the energy landscape in the United States. However, the environmental impacts associated with fracking for shale gas have made it controversial. This review examines emissions and impacts of air pollutants associated with shale gas production and use. Emissions and impacts of greenhouse gases, photochemically active air pollutants, and toxic air pollutants are described. In addition to the direct atmospheric impacts of expanded natural gas production, indirect effects are also described. Widespread availability of shale gas can drive down natural gas prices, which, in turn, can impact the use patterns for natural gas. Natural gas production and use in electricity generation are used as a case study for examining these indirect consequences of expanded natural gas availability.

  19. Fractal Analysis of Air Pollutant Concentrations

    NASA Astrophysics Data System (ADS)

    Cortina-Januchs, M. G.; Barrón-Adame, J. M.; Vega-Corona, A.; Andina, D.

    2010-05-01

    Air pollution poses significant threats to human health and the environment throughout the developed and developing countries. This work focuses on fractal analysis of pollutant concentration in Salamanca, Mexico. The city of Salamanca has been catalogued as one of the most polluted cities in Mexico. The main causes of pollution in this city are fixed emission sources, such as chemical industry and electricity generation. Sulphur Dioxide (SO2) and Particulate Matter less than 10 micrometer in diameter (PM10) are the most important pollutants in this region. Air pollutant concentrations were investigated by applying the box counting method in time series obtained of the Automatic Environmental Monitoring Network (AEMN). One year of time series of hourly average concentrations were analyzed in order to characterize the temporal structures of SO2 and PM10.

  20. Macro-kinetic investigation on phenol uptake from air by biofiltration: Influence of superficial gas flow rate and inlet pollutant concentration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zilli, M.; Fabiano, B.; Ferraiolo, A.

    1996-02-20

    The macro-kinetic behavior of phenol removal from a synthetic exhaust gas was investigated theoretically as well as experimentally by means of two identical continuously operating laboratory-scale biological filter bed columns. A mixture of peat and glass beads was used as filter material. After sterilization it was inoculated with a pure strain of Pseudomonas putida, as employed in previous experimental studies. To determine the influence of the superficial gas flow rate on biofilter performance and to evaluate the phenol concentration profiles along the column, two series of continuous tests were carried out varying either the inlet phenol concentration, up to 1,650more » mg {center_dot} m{sup {minus}3}, or the superficial gas flow rate, from 30 to 460 m{sup 3} {center_dot} m{sup {minus}2} {center_dot} h{sup {minus}1}. The elimination capacity of the biofilter is proved by a maximum volumetric phenol removal rate of 0.73 kg {center_dot} m{sup {minus}3} {center_dot} h{sup {minus}1}. The experimental results are consistent with a biofilm model incorporating first-order substrate elimination kinetics. The model may be considered a useful tool in scaling-up a biofiltration system. Furthermore, the deodorization capacity of the biofilter was investigated, at inlet phenol concentrations up to 280 mg {center_dot} m{sup {minus}3} and superficial gas flow rates ranging from 30 to 92 m{sup 3} {center_dot} m{sup {minus}2} {center_dot} h{sup {minus}1}. The deodorization of the gas was achieved at a maximum inlet phenol concentration of about 255 mg {center_dot} m{sup {minus}3}, operating at a superficial gas flow rate of 30 m{sup 3} {center_dot} m{sup {minus}2} {center_dot} h{sup {minus}1}.« less

  1. Sequestration of flue gas CO₂ by direct gas-solid carbonation of air pollution control system residues.

    PubMed

    Tian, Sicong; Jiang, Jianguo

    2012-12-18

    Direct gas-solid carbonation reactions of residues from an air pollution control system (APCr) were conducted using different combinations of simulated flue gas to study the impact on CO₂ sequestration. X-ray diffraction analysis of APCr determined the existence of CaClOH, whose maximum theoretical CO₂ sequestration potential of 58.13 g CO₂/kg APCr was calculated by the reference intensity ratio method. The reaction mechanism obeyed a model of a fast kinetics-controlled process followed by a slow product layer diffusion-controlled process. Temperature is the key factor in direct gas-solid carbonation and had a notable influence on both the carbonation conversion and the CO₂ sequestration rate. The optimal CO₂ sequestrating temperature of 395 °C was easily obtained for APCr using a continuous heating experiment. CO₂ content in the flue gas had a definite influence on the CO₂ sequestration rate of the kinetics-controlled process, but almost no influence on the final carbonation conversion. Typical concentrations of SO₂ in the flue gas could not only accelerate the carbonation reaction rate of the product layer diffusion-controlled process, but also could improve the final carbonation conversion. Maximum carbonation conversions of between 68.6% and 77.1% were achieved in a typical flue gas. Features of rapid CO₂ sequestration rate, strong impurities resistance, and high capture conversion for direct gas-solid carbonation were proved in this study, which presents a theoretical foundation for the applied use of this encouraging technology on carbon capture and storage.

  2. Evaluation of background soil and air polychlorinated biphenyl (PCB) concentrations on a hill at the outskirts of a metropolitan city.

    PubMed

    Kuzu, S Levent; Saral, Arslan; Güneş, Gülten; Karadeniz, Aykut

    2016-07-01

    Air and soil sampling was conducted inside a forested area for 22 months. The sampling location is situated to the north of a metropolitan city. Average atmospheric gas and particle concentrations were found to be 180 and 28 pg m(-3) respectively, while that of soil phase was detected to be 3.2 ng g(-1) on dry matter, The congener pairs of PCB#4-10 had the highest contribution to each medium. TEQ concentration was 0.10 pg m(-3), 0.07 pg m(-3), 21.92 pg g(-1), for gas, particle and soil phases, respectively. PCB#126 and PCB#169 contributed to over 99% of the entire TEQ concentrations for each medium. Local sources were investigated by conditional probability function (CPF) and soil/air fugacity. Landfilling area and medical waste incinerator, located to the 8 km northeast, contributed to ambient concentrations, especially in terms of dioxin-like congeners. The industrial settlement (called Dilovasi being to the east southeast of 60 km distant) contributed from southeast direction. Further sources were identified by potential source contribution function (PSCF). Sources at close proximity had high contribution. Air mass transportation from Aliaga industrial region (being to the southwest of 300 km distant) moderately contributed to ambient concentrations. Low molecular weight congeners were released from soil body. 5-CBs and 6-CBs were close to equilibrium state between soil/air interfaces. PCB#171 was close to equilibrium and PCB#180 was likely to evaporate from soil, which constitute 7-CBs. PCB#199, representing 8-CBs deposited to soil. 9-CB (PCB#207) was in equilibrium between soil and air phases. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Spume Drops: Their Potential Role in Air-Sea Gas Exchange

    NASA Astrophysics Data System (ADS)

    Monahan, Edward C.; Staniec, Allison; Vlahos, Penny

    2017-12-01

    After summarizing the time scales defining the change of the physical properties of spume and other droplets cast up from the sea surface, the time scales governing drop-atmosphere gas exchange are compared. Following a broad review of the spume drop production functions described in the literature, a subset of these functions is selected via objective criteria, to represent typical, upper bound, and lower bound production functions. Three complementary mechanisms driving spume-atmosphere gas exchange are described, and one is then used to estimate the relative importance, over a broad range of wind speeds, of this spume drop mechanism compared to the conventional, diffusional, sea surface mechanism in air-sea gas exchange. While remaining uncertainties in the wind dependence of the spume drop production flux, and in the immediate sea surface gas flux, preclude a definitive conclusion, the findings of this study strongly suggest that, at high wind speeds (>20 m s-1 for dimethyl sulfide and >30 m s-1 for gases such a carbon dioxide), spume drops do make a significant contribution to air-sea gas exchange.Plain Language SummaryThis paper evaluates the existing spume drop generation functions available to date and selects a reasonable upper, lower and mid range function that are reasonable for use in <span class="hlt">air</span> sea exchange models. Based on these the contribution of spume drops to overall <span class="hlt">air</span> sea <span class="hlt">gas</span> exchange at different wind speeds is then evaluated to determine the % contribution of spume. Generally below 20ms-1 spume drops contribute <1% of <span class="hlt">gas</span> exchange but may account for a significant amount of <span class="hlt">gas</span> exchange at higher wind speeds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..302a2029N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..302a2029N"><span><span class="hlt">Gas</span>-Dynamic Designing of the Exhaust System for the <span class="hlt">Air</span> Brake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Novikova, Yu; Goriachkin, E.; Volkov, A.</p> <p>2018-01-01</p> <p>Each <span class="hlt">gas</span> turbine engine is tested some times during the life-cycle. The test equipment includes the <span class="hlt">air</span> brake that utilizes the power produced by the <span class="hlt">gas</span> turbine engine. In actual conditions, the outlet pressure of the <span class="hlt">air</span> brake does not change and is equal to atmospheric pressure. For this reason, for the <span class="hlt">air</span> brake work it is necessary to design the special exhaust system. Mission of the exhaust system is to provide the required level of backpressure at the outlet of the <span class="hlt">air</span> brake. The backpressure is required for the required power utilization by the <span class="hlt">air</span> brake (the <span class="hlt">air</span> brake operation in the required points on the performance curves). The paper is described the development of the <span class="hlt">gas</span> dynamic canal, designing outlet guide vane and the creation of a unified exhaust system for the <span class="hlt">air</span> brake. Using a unified exhaust system involves moving the operating point to the performance curve further away from the calculated point. However, the applying of one exhaust system instead of two will significantly reduce the cash and time costs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9231999','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9231999"><span><span class="hlt">Concentrations</span> of selected contaminants in cabin <span class="hlt">air</span> of airbus aircrafts.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dechow, M; Sohn, H; Steinhanses, J</p> <p>1997-07-01</p> <p>The <span class="hlt">concentrations</span> of selected <span class="hlt">air</span> quality parameters in aircraft cabins were investigated including particle numbers in cabin <span class="hlt">air</span> compared to fresh <span class="hlt">air</span> and recirculation <span class="hlt">air</span>, the microbiological contamination and the <span class="hlt">concentration</span> of volatile organic compounds (VOC). The Airbus types A310 of Swissair and A340 of Lufthansa were used for measurements. The particles were found to be mainly emitted by the passengers, especially by smokers. Depending on recirculation filter efficiency the recirculation <span class="hlt">air</span> contained a lower or equal amount of particles compared to the fresh <span class="hlt">air</span>, whereas the amount of bacteria exceeded reported <span class="hlt">concentrations</span> within other indoor spaces. The detected species were mainly non-pathogenic, with droplet infection over short distances identified as the only health risk. The <span class="hlt">concentration</span> of volatile organic compounds (VOC) were well below threshold values. Ethanol was identified as the compound with the highest amount in cabin <span class="hlt">air</span>. Further organics were emitted by the passengers--as metabolic products or by smoking--and on ground as engine exhaust (bad airport <span class="hlt">air</span> quality). Cleaning agents may be the source of further compounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.939a2002F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.939a2002F"><span>Development of metal oxide <span class="hlt">gas</span> sensors for very low <span class="hlt">concentration</span> (ppb) of BTEX vapors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Favard, A.; Aguir, K.; Contaret, T.; Caris, L.; Bendahan, M.</p> <p>2017-12-01</p> <p>The control and analysis of <span class="hlt">air</span> quality have become a major preoccupation of the last twenty years. In 2008, the European Union has introduced a Directive (2008/50/EC) to impose measurement obligations and thresholds to not exceed for some pollutants, including BTEX gases, in view of their adverse effects on the health. In this paper, we show the ability to detect very low <span class="hlt">concentrations</span> of BTEX using a <span class="hlt">gas</span> microsensor based on metal oxide thin-film. A test bench able to generate very low vapors <span class="hlt">concentrations</span> has been achieved and fully automated. Thin metal oxides layers have been realized by reactive magnetron sputtering. The sensitive layers are functionalized with gold nanoparticles by thermal evaporation technique. Our sensors have been tested on a wide range of <span class="hlt">concentrations</span> of BTEX (5 - 500 ppb) and have been able to detect <span class="hlt">concentrations</span> of a few ppb for operating temperatures below 593 K. These results are very promising for detection of very low BTEX <span class="hlt">concentration</span> for indoor as well as outdoor application. We showed that the addition of gold nanoparticles on the sensitive layers decreases the sensors operating temperature and increases the response to BTEX <span class="hlt">gas</span>. The best results are obtained with a sensitive layer based on ZnO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5038181','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/5038181"><span>Wide-range radioactive-<span class="hlt">gas-concentration</span> detector</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Anderson, D.F.</p> <p>1981-11-16</p> <p>A wide-range radioactive-<span class="hlt">gas-concentration</span> detector and monitor capable of measuring radioactive-<span class="hlt">gas</span> <span class="hlt">concentrations</span> over a range of eight orders of magnitude is described. The device is designed to have an ionization chamber sufficiently small to give a fast response time for measuring radioactive gases but sufficiently large to provide accurate readings at low <span class="hlt">concentration</span> levels. Closely spaced parallel-plate grids provide a uniform electric field in the active region to improve the accuracy of measurements and reduce ion migration time so as to virtually eliminate errors due to ion recombination. The parallel-plate grids are fabricated with a minimal surface area to reduce the effects of contamination resulting from absorption of contaminating materials on the surface of the grids. Additionally, the ionization-chamber wall is spaced a sufficient distance from the active region of the ionization chamber to minimize contamination effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JCoPh.271..172N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JCoPh.271..172N"><span>Reprint of: A numerical modelling of <span class="hlt">gas</span> exchange mechanisms between <span class="hlt">air</span> and turbulent water with an aquarium chemical reaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nagaosa, Ryuichi S.</p> <p>2014-08-01</p> <p>This paper proposes a new numerical modelling to examine environmental chemodynamics of a gaseous material exchanged between the <span class="hlt">air</span> and turbulent water phases across a <span class="hlt">gas</span>-liquid interface, followed by an aquarium chemical reaction. This study uses an extended concept of a two-compartment model, and assumes two physicochemical substeps to approximate the <span class="hlt">gas</span> exchange processes. The first substep is the <span class="hlt">gas</span>-liquid equilibrium between the <span class="hlt">air</span> and water phases, A(g)⇌A(aq), with Henry's law constant H. The second is a first-order irreversible chemical reaction in turbulent water, A(aq)+H2O→B(aq)+H+ with a chemical reaction rate κA. A direct numerical simulation (DNS) technique has been employed to obtain details of the <span class="hlt">gas</span> exchange mechanisms and the chemical reaction in the water compartment, while zero velocity and uniform <span class="hlt">concentration</span> of A is considered in the <span class="hlt">air</span> compartment. The study uses the different Schmidt numbers between 1 and 8, and six nondimensional chemical reaction rates between 10(≈0) to 101 at a fixed Reynolds number. It focuses on the effects of the Schmidt number and the chemical reaction rate on fundamental mechanisms of the <span class="hlt">gas</span> exchange processes across the interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/443381-effect-ozone-generating-air-purifying-device-reducing-concentrations-formaldehyde-air','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/443381-effect-ozone-generating-air-purifying-device-reducing-concentrations-formaldehyde-air"><span>Effect of an ozone-generating <span class="hlt">air</span>-purifying device on reducing <span class="hlt">concentrations</span> of formaldehyde in <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Esswein, E.J.; Boeniger, M.F.</p> <p>1994-02-01</p> <p>Formaldehyde, an <span class="hlt">air</span> contaminant found in many indoor <span class="hlt">air</span> investigations, poses distinct occupational exposure hazards in certain job categories (e.g., mortuary science) but is also of concern when found or suspected in office buildings and homes. A variety of <span class="hlt">air</span>-purifying devices (APDs) are currently available or marketed for application to reduce or remove <span class="hlt">concentrations</span> of a variety of indoor <span class="hlt">air</span> pollutants through the use of ozone as a chemical oxidant. An investigation was conducted to determine if <span class="hlt">concentrations</span> of formaldehyde similar to those found in industrial hygiene evaluations of funeral homes could be reduced with the use of an ozone-generatingmore » APD. An ozone-generating APD was placed in an exposure chamber and formaldehyde-containing embalming solution was allowed to evaporate naturally, creating peak and mean chamber <span class="hlt">concentrations</span> of 2.5 and 1.3 ppm, respectively. Continuous-reading instruments were used to sample for formaldehyde and ozone. Active sampling methods were also used to sample simultaneously for formaldehyde and a possible reactant product, formic acid. Triplicate measurements were made in each of three evaluations: formaldehyde alone, ozone alone, and formaldehyde and ozone combined. <span class="hlt">Concentrations</span> of formaldehyde were virtually identical with and without 0.5 ppm ozone. No reduction in formaldehyde <span class="hlt">concentration</span> was found during a 90-minute evaluation using ozone at this <span class="hlt">concentration</span> with peak and average <span class="hlt">concentrations</span> of approximately 2.5 and 1.3 ppm formaldehyde, respectively. The results of this investigation suggest that the use of ozone is ineffective in reducing <span class="hlt">concentrations</span> of formaldehyde. Because ozone has demonstrated health hazards, and is a regulated <span class="hlt">air</span> contaminant in both the occupational and ambient environment, the use of ozone as an <span class="hlt">air</span> purification agent in indoor <span class="hlt">air</span> does not seem warranted. 25 refs., 5 figs., 4 tabs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16916532','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16916532"><span>Influence of <span class="hlt">air</span> humidity and the distance from the source on negative <span class="hlt">air</span> ion <span class="hlt">concentration</span> in indoor <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, Chih Cheng; Lee, Grace W M; Yang, Shinhao; Yu, Kuo-Pin; Lou, Chia Ling</p> <p>2006-10-15</p> <p>Although negative <span class="hlt">air</span> ionizer is commonly used for indoor <span class="hlt">air</span> cleaning, few studies examine the <span class="hlt">concentration</span> gradient of negative <span class="hlt">air</span> ion (NAI) in indoor environments. This study investigated the <span class="hlt">concentration</span> gradient of NAI at various relative humidities and distances form the source in indoor <span class="hlt">air</span>. The NAI was generated by single-electrode negative electric discharge; the discharge was kept at dark discharge and 30.0 kV. The NAI <span class="hlt">concentrations</span> were measured at various distances (10-900 cm) from the discharge electrode in order to identify the distribution of NAI in an indoor environment. The profile of NAI <span class="hlt">concentration</span> was monitored at different relative humidities (38.1-73.6% RH) and room temperatures (25.2+/-1.4 degrees C). Experimental results indicate that the influence of relative humidity on the <span class="hlt">concentration</span> gradient of NAI was complicated. There were four trends for the relationship between NAI <span class="hlt">concentration</span> and relative humidity at different distances from the discharge electrode. The changes of NAI <span class="hlt">concentration</span> with an increase in relative humidity at different distances were quite steady (10-30 cm), strongly declining (70-360 cm), approaching stability (420-450 cm) and moderately increasing (560-900 cm). Additionally, the regression analysis of NAI <span class="hlt">concentrations</span> and distances from the discharge electrode indicated a logarithmic linear (log-linear) relationship; the distance of log-linear tendency (lambda) decreased with an increase in relative humidity such that the log-linear distance of 38.1% RH was 2.9 times that of 73.6% RH. Moreover, an empirical curve fit based on this study for the <span class="hlt">concentration</span> gradient of NAI generated by negative electric discharge in indoor <span class="hlt">air</span> was developed for estimating the NAI <span class="hlt">concentration</span> at different relative humidities and distances from the source of electric discharge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title10-vol4/pdf/CFR-2013-title10-vol4-sec835-209.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title10-vol4/pdf/CFR-2013-title10-vol4-sec835-209.pdf"><span>10 CFR 835.209 - <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-01-01</p> <p>... 10 Energy 4 2013-01-01 2013-01-01 false <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>. 835.209 Section 835.209 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External Exposure § 835.209 <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>. (a) The derived <span class="hlt">air</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title10-vol4/pdf/CFR-2012-title10-vol4-sec835-209.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title10-vol4/pdf/CFR-2012-title10-vol4-sec835-209.pdf"><span>10 CFR 835.209 - <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 10 Energy 4 2012-01-01 2012-01-01 false <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>. 835.209 Section 835.209 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External Exposure § 835.209 <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>. (a) The derived <span class="hlt">air</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title10-vol4/pdf/CFR-2011-title10-vol4-sec835-209.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title10-vol4/pdf/CFR-2011-title10-vol4-sec835-209.pdf"><span>10 CFR 835.209 - <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... 10 Energy 4 2011-01-01 2011-01-01 false <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>. 835.209 Section 835.209 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External Exposure § 835.209 <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>. (a) The derived <span class="hlt">air</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title10-vol4/pdf/CFR-2014-title10-vol4-sec835-209.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title10-vol4/pdf/CFR-2014-title10-vol4-sec835-209.pdf"><span>10 CFR 835.209 - <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-01-01</p> <p>... 10 Energy 4 2014-01-01 2014-01-01 false <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>. 835.209 Section 835.209 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External Exposure § 835.209 <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>. (a) The derived <span class="hlt">air</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/864939','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/864939"><span>Wide range radioactive <span class="hlt">gas</span> <span class="hlt">concentration</span> detector</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Anderson, David F.</p> <p>1984-01-01</p> <p>A wide range radioactive <span class="hlt">gas</span> <span class="hlt">concentration</span> detector and monitor which is capable of measuring radioactive <span class="hlt">gas</span> <span class="hlt">concentrations</span> over a range of eight orders of magnitude. The device of the present invention is designed to have an ionization chamber which is sufficiently small to give a fast response time for measuring radioactive gases but sufficiently large to provide accurate readings at low <span class="hlt">concentration</span> levels. Closely spaced parallel plate grids provide a uniform electric field in the active region to improve the accuracy of measurements and reduce ion migration time so as to virtually eliminate errors due to ion recombination. The parallel plate grids are fabricated with a minimal surface area to reduce the effects of contamination resulting from absorption of contaminating materials on the surface of the grids. Additionally, the ionization chamber wall is spaced a sufficient distance from the active region of the ionization chamber to minimize contamination effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........15Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........15Q"><span>The <span class="hlt">Air</span>-Carbon-Water Synergies and Trade-Offs in China's Natural <span class="hlt">Gas</span> Industry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qin, Yue</p> <p></p> <p>China's coal-dominated energy structure is partly responsible for its domestic <span class="hlt">air</span> pollution, local water stress, and the global climate change. Primarily to tackle the haze issue, China has been actively promoting a nationwide coal to natural <span class="hlt">gas</span> end-use switch. My dissertation focuses on evaluating the <span class="hlt">air</span> quality, carbon, and water impacts and their interactions in China's natural <span class="hlt">gas</span> industry. Chapter 2 assesses the lifecycle climate performance of China's shale <span class="hlt">gas</span> in comparison to coal based on stage-level energy consumption and methane leakage rates. I find the mean lifecycle carbon footprint of shale <span class="hlt">gas</span> is about 30-50% lower than that of coal under both 20 year and 100 year global warming potentials (GWP20 and GWP100). However, primarily due to large uncertainties in methane leakage, the lifecycle carbon footprint of shale <span class="hlt">gas</span> in China could be 15-60% higher than that of coal across sectors under GWP20. Chapter 3 evaluates the <span class="hlt">air</span> quality, human health, and the climate impacts of China's coal-based synthetic natural <span class="hlt">gas</span> (SNG) development. Based on earlier 2020 SNG production targets, I conduct an integrated assessment to identify production technologies and end-use applications that will bring as large <span class="hlt">air</span> quality and health benefits as possible while keeping carbon penalties as small as possible. I find that, due to inefficient and uncontrolled coal combustion in households, allocating currently available SNG to the residential sector proves to be the best SNG allocation option. Chapter 4 compares the <span class="hlt">air</span> quality, carbon, and water impacts of China's six major <span class="hlt">gas</span> sources under three end-use substitution scenarios, which are focused on maximizing <span class="hlt">air</span> pollutant emission reductions, CO 2 emission reductions, and water stress index (WSI)-weighted water consumption reductions, respectively. I find striking national <span class="hlt">air</span>-carbon/water trade-offs due to SNG, which also significantly increases water demands and carbon emissions in regions already suffering from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol34/pdf/CFR-2012-title40-vol34-sec1065-308.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol34/pdf/CFR-2012-title40-vol34-sec1065-308.pdf"><span>40 CFR 1065.308 - Continuous <span class="hlt">gas</span> analyzer system-response and updating-recording verification-for <span class="hlt">gas</span> analyzers not...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calibrations and Verifications § 1065.308 Continuous..., the <span class="hlt">gas</span> <span class="hlt">concentrations</span> must be adjusted to account for the dilution from ambient <span class="hlt">air</span> drawn into the... recommended when blending span gases diluted in N2 with span gases diluted in <span class="hlt">air</span>. You may use a multi-<span class="hlt">gas</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol34/pdf/CFR-2013-title40-vol34-sec1065-308.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol34/pdf/CFR-2013-title40-vol34-sec1065-308.pdf"><span>40 CFR 1065.308 - Continuous <span class="hlt">gas</span> analyzer system-response and updating-recording verification-for <span class="hlt">gas</span> analyzers not...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calibrations and Verifications § 1065.308 Continuous..., the <span class="hlt">gas</span> <span class="hlt">concentrations</span> must be adjusted to account for the dilution from ambient <span class="hlt">air</span> drawn into the... recommended when blending span gases diluted in N2 with span gases diluted in <span class="hlt">air</span>. You may use a multi-<span class="hlt">gas</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10547951','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10547951"><span>Determination of methyltetrahydrophthalic anhydride in <span class="hlt">air</span> using <span class="hlt">gas</span> chromatography with electron-capture detection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Johyama, Y; Yokota, K; Fujiki, Y; Takeshita, T; Morimoto, K</p> <p>1999-10-01</p> <p>Methyltetrahydrophthalic anhydride (MTHPA) stimulates the production of specific IgE antibodies which can cause occupational allergy even at extremely low levels of exposure (15-22 micrograms/m3). Safe use in industry demands control of the levels of exposure causing allergic diseases. Thus, the <span class="hlt">air</span> monitoring of MTHPA is very important, and sensitive methods are required to measure low <span class="hlt">air</span> <span class="hlt">concentrations</span> or short-time peak exposures. This paper outlines the use of silica-gel tubes for sampling airborne MTHPA vapour, followed by analysis using <span class="hlt">gas</span> chromatography with electron-capture detection. No breakthrough was observed at 113, 217, 673 and 830 micrograms/m3 (sampling volume 30, 60, 60 and 20 l, respectively; relative humidity 40-55%). <span class="hlt">Concentrations</span> > 1.0 microgram/m3 could be quantified at 20-min sampling with a sampling rate of 1 l/min. The present method can also be applied to measurements of exposure to hexahydrophthalic and methylhexahydrophthalic anhydride. The risk of MTHPA exposure in two condenser plants was also assessed by determining MTHPA levels in <span class="hlt">air</span> of the workplace. In conclusion, our method was found to be reliable and sensitive, and can be applied to the evaluation of MTHPA exposure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SPIE.9141E..1ZC','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9141E..1ZC"><span>Analyzer for measurement of nitrogen oxide <span class="hlt">concentration</span> by ozone content reduction in <span class="hlt">gas</span> using solid state chemiluminescent sensor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chelibanov, V. P.; Ishanin, G. G.; Isaev, L. N.</p> <p>2014-05-01</p> <p>Role of nitrogen oxide in ambient <span class="hlt">air</span> is described and analyzed. New method of nitrogen oxide <span class="hlt">concentration</span> measurement in <span class="hlt">gas</span> phase is suggested based on ozone <span class="hlt">concentration</span> measurement with titration by nitrogen oxide. Research of chemiluminescent sensor composition is carried out on experimental stand. The sensor produced on the base of solid state non-activated chemiluminescent composition is applied as ozone sensor. Composition is put on the surface of polymer matrix with developed surface. Sensor compositions includes gallic acid with addition of rodamine-6G. Model of interaction process between sensor composition and ozone has been developed, main products appeared during reaction are identified. The product determining the speed of luminescense appearance is found. This product belongs to quinone class. Then new structure of chemiluminescent composition was suggested, with absence of activation period and with high stability of operation. Experimental model of <span class="hlt">gas</span> analyzer was constructed and operation algorithm was developed. It was demonstrated that developed NO measuring instrument would be applied for monitoring purposes of ambient <span class="hlt">air</span>. This work was partially financially supported by Government of Russian Federation, Grant 074-U01</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AtmEn..95..207W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AtmEn..95..207W"><span>Atmospheric <span class="hlt">concentrations</span> and <span class="hlt">gas</span>/particle partitioning of neutral poly- and perfluoroalkyl substances in northern German coast</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Zhen; Xie, Zhiyong; Möller, Axel; Mi, Wenying; Wolschke, Hendrik; Ebinghaus, Ralf</p> <p>2014-10-01</p> <p>Total 58 high volume <span class="hlt">air</span> samples were collected in Büsum, Germany, from August 2011 to October 2012 to investigate <span class="hlt">air</span> <span class="hlt">concentrations</span> of 12 per- and polyfluoroalkyl substances (PFASs) and their <span class="hlt">gas</span>/particle partitioning. The total <span class="hlt">concentration</span> (vapor plus particle phases) of the 12 PFASs (ΣPFASs) ranged from 8.6 to 155 pg/m3 (mean: 41 pg/m3) while fluorotelomer alcohols 8:2 (8:2 FTOH) dominated all samples accounting for 61.9% of ΣPFASs and the next most species were 10:2 FTOH (12.7%). <span class="hlt">Air</span> mass back trajectory analysis showed that atmospheric PFASs in most samples were from long range atmospheric transport processes and had higher ratios of 8:2 to 6:2 FTOH compared to the data obtained from urban/industrial sources. Small portion of particle PFASs in the atmosphere was observed and the average percent to ΣPFASs was 2.0%. The particle-associated fractions of different PFASs decreased from perfluorooctane sulfonamidoethanols (FOSEs) (15.5%) to fluorotelomer acrylates (FTAs) (7.6%) to perfluorooctane sulfonamides (FOSAs) (3.1%) and FTOHs (1.8%), indicating the functional group obviously influenced their <span class="hlt">gas</span>/particle partitioning. For neutral compounds with acid dissociation constant (pKa) > 7.0 (i.e., FTOHs, FOSEs and FOSAs), a significant log-linear relationship was observed between their <span class="hlt">gas</span>/particle partition coefficients (KSP) and vapor pressures (pºL), suggesting the <span class="hlt">gas</span>/particle partitioning of neutral PFASs agreed with the classical logKSP-logpºL relation. Due to the pKa values of 6:2 and 8:2 FTA below the typical environmental pH conditions, they mainly exist as ionic form in aerosols, and the corrected logKSP (neutral form) were considerably lower than those of FTOHs, FOSEs and FOSAs with similar vapor pressures. Considering the strong partitioning potential to aqueous phases for ionic PFASs at higher pH values, a need exists to develop a model taking account of the ad/absorption mechanism to the condensed phase of aerosols for ionizable PFASs (e</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25533373','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25533373"><span>[Determination a variety of acidic <span class="hlt">gas</span> in <span class="hlt">air</span> of workplace by Ion Chromatography].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Shiyong</p> <p>2014-10-01</p> <p>To establish a method for determination of a variety of acid <span class="hlt">gas</span> in the workplace <span class="hlt">air</span> by Ion Chromatography. (hydrofluoric acid, hydrogen chloride or hydrochloric acid, sulfur anhydride or sulfuric acid, phosphoric acid, oxalic acid). The sample in workplace <span class="hlt">air</span> was collected by the porous glass plate absorption tube containing 5 ml leacheate. (Sulfuric acid fog, phosphoric acid aerosol microporous membrane after collection, eluted with 5 ml of eluent.) To separated by AS14+AG14 chromatography column, by carbonate (2.0+1.0) mmol/L (Na(2)CO(3)-NaHCO(3)) as eluent, flow rate of 1 ml/min, then analyzed by electrical conductivity detector. The retain time was used for qualitative and the peak area was used for quantitation. The each ion of a variety of acid <span class="hlt">gas</span> in the <span class="hlt">air</span> of workplace were excellent in carbonate eluent separation. The linear range of working curve of 0∼20 mg/L. The correlation coefficient r>0.999; lower detection limit of 3.6∼115 µg/L; quantitative limit of 0.012∼0.53 mg/L; acquisition of 15L <span class="hlt">air</span> were measured, the minimum detection <span class="hlt">concentration</span> is 0.004 0∼0.13 mg/m(3). The recovery rate is 99.7%∼101.1%. In the sample without mutual interference ions. Samples stored at room temperature for 7 days. The same analysis method, the detection of various acidic gases in the <span class="hlt">air</span> of workplace, simple operation, good separation effect, high sensitivity, high detection efficiency, easy popularization and application.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MeScT..29a5901L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MeScT..29a5901L"><span>Characterization and calibration of <span class="hlt">gas</span> sensor systems at ppb level—a versatile test <span class="hlt">gas</span> generation system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leidinger, Martin; Schultealbert, Caroline; Neu, Julian; Schütze, Andreas; Sauerwald, Tilman</p> <p>2018-01-01</p> <p>This article presents a test <span class="hlt">gas</span> generation system designed to generate ppb level <span class="hlt">gas</span> <span class="hlt">concentrations</span> from <span class="hlt">gas</span> cylinders. The focus is on permanent gases and volatile organic compounds (VOCs) for applications like indoor and outdoor <span class="hlt">air</span> quality monitoring or breath analysis. In the design and the setup of the system, several issues regarding handling of trace <span class="hlt">gas</span> <span class="hlt">concentrations</span> have been considered, addressed and tested. This concerns not only the active fluidic components (flow controllers, valves), which have been chosen specifically for the task, but also the design of the fluidic tubing regarding dead volumes and delay times, which have been simulated for the chosen setup. Different tubing materials have been tested for their adsorption/desorption characteristics regarding naphthalene, a highly relevant <span class="hlt">gas</span> for indoor <span class="hlt">air</span> quality monitoring, which has generated high <span class="hlt">gas</span> exchange times in a previous <span class="hlt">gas</span> mixing system due to long time adsorption/desorption effects. Residual <span class="hlt">gas</span> contaminations of the system and the selected carrier <span class="hlt">air</span> supply have been detected and quantified using both an analytical method (GC-MS analysis according to ISO 16000-6) and a metal oxide semiconductor <span class="hlt">gas</span> sensor, which detected a maximum contamination equivalent to 28 ppb of carbon monoxide. A measurement strategy for suppressing even this contamination has been devised, which allows the system to be used for <span class="hlt">gas</span> sensor and <span class="hlt">gas</span> sensor system characterization and calibration in the low ppb <span class="hlt">concentration</span> range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14567951','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14567951"><span>A simple bubbling system for measuring radon (222Rn) <span class="hlt">gas</span> <span class="hlt">concentrations</span> in water samples based on the high solubility of radon in olive oil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Al-Azmi, D; Snopek, B; Sayed, A M; Domanski, T</p> <p>2004-01-01</p> <p>Based on the different levels of solubility of radon <span class="hlt">gas</span> in organic solvents and water, a bubbling system has been developed to transfer radon <span class="hlt">gas</span>, dissolving naturally in water samples, to an organic solvent, i.e. olive oil, which is known to be a good solvent of radon <span class="hlt">gas</span>. The system features the application of a fixed volume of bubbling <span class="hlt">air</span> by introducing a fixed volume of water into a flask mounted above the system, to displace an identical volume of <span class="hlt">air</span> from an <span class="hlt">air</span> cylinder. Thus a gravitational flow of water is provided without the need for pumping. Then, the flushing <span class="hlt">air</span> (radon-enriched <span class="hlt">air</span>) is directed through a vial containing olive oil, to achieve deposition of the radon <span class="hlt">gas</span> by another bubbling process. Following this, the vial (containing olive oil) is measured by direct use of gamma ray spectrometry, without the need of any chemical or physical processing of the samples. Using a standard solution of 226Ra/222Rn, a lowest measurable <span class="hlt">concentration</span> (LMC) of radon in water samples of 9.4 Bq L(-1) has been achieved (below the maximum contaminant level of 11 Bq L(-1)).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/918207','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/918207"><span>Biomimetic <span class="hlt">air</span> sampling for detection of low <span class="hlt">concentrations</span> of molecules and bioagents : LDRD 52744 final report.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hughes, Robert Clark</p> <p>2003-12-01</p> <p>Present methods of <span class="hlt">air</span> sampling for low <span class="hlt">concentrations</span> of chemicals like explosives and bioagents involve noisy and power hungry collectors with mechanical parts for moving large volumes of <span class="hlt">air</span>. However there are biological systems that are capable of detecting very low <span class="hlt">concentrations</span> of molecules with no mechanical moving parts. An example is the silkworm moth antenna which is a highly branched structure where each of 100 branches contains about 200 sensory 'hairs' which have dimensions of 2 microns wide by 100 microns long. The hairs contain about 3000 pores which is where the <span class="hlt">gas</span> phase molecules enter the aqueous (lymph)more » phase for detection. Simulations of diffusion of molecules indicate that this 'forest' of hairs is 'designed' to maximize the extraction of the vapor phase molecules. Since typical molecules lose about 4 decades in diffusion constant upon entering the liquid phase, it is important to allow <span class="hlt">air</span> diffusion to bring the molecule as close to the 'sensor' as possible. The moth acts on <span class="hlt">concentrations</span> as low as 1000 molecules per cubic cm. (one part in 1e16). A 3-D collection system of these dimensions could be fabricated by micromachining techniques available at Sandia. This LDRD addresses the issues involved with extracting molecules from <span class="hlt">air</span> onto micromachined structures and then delivering those molecules to microsensors for detection.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AtmEn.177..175M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AtmEn.177..175M"><span>Source characterization and exposure modeling of <span class="hlt">gas</span>-phase polycyclic aromatic hydrocarbon (PAH) <span class="hlt">concentrations</span> in Southern California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Masri, Shahir; Li, Lianfa; Dang, Andy; Chung, Judith H.; Chen, Jiu-Chiuan; Fan, Zhi-Hua (Tina); Wu, Jun</p> <p>2018-03-01</p> <p>Airborne exposures to polycyclic aromatic hydrocarbons (PAHs) are associated with adverse health outcomes. Because personal <span class="hlt">air</span> measurements of PAHs are labor intensive and costly, spatial PAH exposure models are useful for epidemiological studies. However, few studies provide adequate spatial coverage to reflect intra-urban variability of ambient PAHs. In this study, we collected 39-40 weekly <span class="hlt">gas</span>-phase PAH samples in southern California twice in summer and twice in winter, 2009, in order to characterize PAH source contributions and develop spatial models that can estimate <span class="hlt">gas</span>-phase PAH <span class="hlt">concentrations</span> at a high resolution. A spatial mixed regression model was constructed, including such variables as roadway, traffic, land-use, vegetation index, commercial cooking facilities, meteorology, and population density. Cross validation of the model resulted in an R2 of 0.66 for summer and 0.77 for winter. Results showed higher total PAH <span class="hlt">concentrations</span> in winter. Pyrogenic sources, such as fossil fuels and diesel exhaust, were the most dominant contributors to total PAHs. PAH sources varied by season, with a higher fossil fuel and wood burning contribution in winter. Spatial autocorrelation accounted for a substantial amount of the variance in total PAH <span class="hlt">concentrations</span> for both winter (56%) and summer (19%). In summer, other key variables explaining the variance included meteorological factors (9%), population density (15%), and roadway length (21%). In winter, the variance was also explained by traffic density (16%). In this study, source characterization confirmed the dominance of traffic and other fossil fuel sources to total measured <span class="hlt">gas</span>-phase PAH <span class="hlt">concentrations</span> while a spatial exposure model identified key predictors of PAH <span class="hlt">concentrations</span>. <span class="hlt">Gas</span>-phase PAH source characterization and exposure estimation is of high utility to epidemiologist and policy makers interested in understanding the health impacts of <span class="hlt">gas</span>-phase PAHs and strategies to reduce emissions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29808078','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29808078"><span>Source Characterization and Exposure Modeling of <span class="hlt">Gas</span>-Phase Polycyclic Aromatic Hydrocarbon (PAH) <span class="hlt">Concentrations</span> in Southern California.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Masri, Shahir; Li, Lianfa; Dang, Andy; Chung, Judith H; Chen, Jiu-Chiuan; Fan, Zhi-Hua Tina; Wu, Jun</p> <p>2018-03-01</p> <p>Airborne exposures to polycyclic aromatic hydrocarbons (PAHs) are associated with adverse health outcomes. Because personal <span class="hlt">air</span> measurements of PAHs are labor intensive and costly, spatial PAH exposure models are useful for epidemiological studies. However, few studies provide adequate spatial coverage to reflect intra-urban variability of ambient PAHs. In this study, we collected 39-40 weekly <span class="hlt">gas</span>-phase PAH samples in southern California twice in summer and twice in winter, 2009, in order to characterize PAH source contributions and develop spatial models that can estimate <span class="hlt">gas</span>-phase PAH <span class="hlt">concentrations</span> at a high resolution. A spatial mixed regression model was constructed, including such variables as roadway, traffic, land-use, vegetation index, commercial cooking facilities, meteorology, and population density. Cross validation of the model resulted in an R 2 of 0.66 for summer and 0.77 for winter. Results showed higher total PAH <span class="hlt">concentrations</span> in winter. Pyrogenic sources, such as fossil fuels and diesel exhaust, were the most dominant contributors to total PAHs. PAH sources varied by season, with a higher fossil fuel and wood burning contribution in winter. Spatial autocorrelation accounted for a substantial amount of the variance in total PAH <span class="hlt">concentrations</span> for both winter (56%) and summer (19%). In summer, other key variables explaining the variance included meteorological factors (9%), population density (15%), and roadway length (21%). In winter, the variance was also explained by traffic density (16%). In this study, source characterization confirmed the dominance of traffic and other fossil fuel sources to total measured <span class="hlt">gas</span>-phase PAH <span class="hlt">concentrations</span> while a spatial exposure model identified key predictors of PAH <span class="hlt">concentrations</span>. <span class="hlt">Gas</span>-phase PAH source characterization and exposure estimation is of high utility to epidemiologist and policy makers interested in understanding the health impacts of <span class="hlt">gas</span>-phase PAHs and strategies to reduce emissions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29248706','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29248706"><span><span class="hlt">Gas</span>/particle partitioning and particle size distribution of PCDD/Fs and PCBs in urban ambient <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Barbas, B; de la Torre, A; Sanz, P; Navarro, I; Artíñano, B; Martínez, M A</p> <p>2018-05-15</p> <p>Urban ambient <span class="hlt">air</span> samples, including <span class="hlt">gas</span>-phase (PUF), total suspended particulates (TSP), PM 10 , PM 2.5 and PM 1 airborne particle fractions were collected to evaluate <span class="hlt">gas</span>-particle partitioning and size particle distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs). Clausius-Clapeyron equation, regressions of logKp vs logP L and logK OA, and human respiratory risk assessment were used to evaluate local or long-distance transport sources, <span class="hlt">gas</span>-particle partitioning sorption mechanisms, and implications for health. Total ambient <span class="hlt">air</span> levels (<span class="hlt">gas</span> phase+particulate phase) of TPCBs and TPCDD/Fs, were 437 and 0.07pgm -3 (median), respectively. Levels of PCDD/F in the <span class="hlt">gas</span> phase (0.004-0.14pgm -3 , range) were significantly (p<0.05) lower than those found in the particulate phase (0.02-0.34pgm -3 ). The <span class="hlt">concentrations</span> of PCDD/Fs were higher in winter. In contrast, PCBs were mainly associated to the <span class="hlt">gas</span> phase, and displayed maximum levels in warm seasons, probably due to an increase in evaporation rates, supported by significant and strong positive dependence on temperature observed for several congeners. No significant differences in PCDD/Fs and PCBs <span class="hlt">concentrations</span> were detected between the different particle size fractions considered (TSP, PM 10 , PM 2.5 and PM 1 ), reflecting that these chemicals are mainly bounded to PM 1 . The toxic content of samples was also evaluated. Total toxicity (PUF+TSP) attributable to dl-PCBs (13.4fg-TEQ 05 m -3 , median) was higher than those reported for PCDD/Fs (6.26fg-TEQ 05 m -3 ). The inhalation risk assessment concluded that the inhalation of PCDD/Fs and dl-PCBs pose a low cancer risk in the studied area. Copyright © 2017 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24329966','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24329966"><span>Home interventions are effective at decreasing indoor nitrogen dioxide <span class="hlt">concentrations</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Paulin, L M; Diette, G B; Scott, M; McCormack, M C; Matsui, E C; Curtin-Brosnan, J; Williams, D L; Kidd-Taylor, A; Shea, M; Breysse, P N; Hansel, N N</p> <p>2014-08-01</p> <p>Nitrogen dioxide (NO2 ), a by-product of combustion produced by indoor <span class="hlt">gas</span> appliances such as cooking stoves, is associated with respiratory symptoms in those with obstructive airways disease. We conducted a three-armed randomized trial to evaluate the efficacy of interventions aimed at reducing indoor NO2 <span class="hlt">concentrations</span> in homes with unvented <span class="hlt">gas</span> stoves: (i) replacement of existing <span class="hlt">gas</span> stove with electric stove; (ii) installation of ventilation hood over existing <span class="hlt">gas</span> stove; and (iii) placement of <span class="hlt">air</span> purifiers with high-efficiency particulate <span class="hlt">air</span> (HEPA) and carbon filters. Home inspection and NO2 monitoring were conducted at 1 week pre-intervention and at 1 week and 3 months post-intervention. Stove replacement resulted in a 51% and 42% decrease in median NO2 <span class="hlt">concentration</span> at 3 months of follow-up in the kitchen and bedroom, respectively (P = 0.01, P = 0.01); <span class="hlt">air</span> purifier placement resulted in an immediate decrease in median NO2 <span class="hlt">concentration</span> in the kitchen (27%, P < 0.01) and bedroom (22%, P = 0.02), but at 3 months, a significant reduction was seen only in the kitchen (20%, P = 0.05). NO2 <span class="hlt">concentrations</span> in the kitchen and bedroom did not significantly change following ventilation hood installation. Replacing unvented <span class="hlt">gas</span> stoves with electric stoves or placement of <span class="hlt">air</span> purifiers with HEPA and carbon filters can decrease indoor NO2 <span class="hlt">concentrations</span> in urban homes. Several combustion sources unique to the residential indoor environment, including <span class="hlt">gas</span> stoves, produce nitrogen dioxide (NO2), and higher NO2 <span class="hlt">concentrations</span>, are associated with worse respiratory morbidity in people with obstructive lung disease. A handful of studies have modified the indoor environment by replacing unvented <span class="hlt">gas</span> heaters; this study, to our knowledge, is the first randomized study to target unvented <span class="hlt">gas</span> stoves. The results of this study show that simple home interventions, including replacement of an unvented <span class="hlt">gas</span> stove with an electric stove or placement of HEPA <span class="hlt">air</span> purifiers with carbon</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770021523','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770021523"><span>Three field tests of a <span class="hlt">gas</span> filter correlation radiometer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Campbell, S. A.; Casas, J. C.; Condon, E. P.</p> <p>1977-01-01</p> <p>Test flights to remotely measure nonurban carbon monoxide (CO) <span class="hlt">concentrations</span> by <span class="hlt">gas</span> filter correlation radiometry are discussed. The inferred CO <span class="hlt">concentrations</span> obtained through use of the <span class="hlt">Gas</span> Filter Correlation Radiometer (GFCR) agreed with independent measurements obtained by <span class="hlt">gas</span> chromatography <span class="hlt">air</span> sample bottle analysis to within 20 percent. The equipment flown on board the aircraft, the flight test procedure, the <span class="hlt">gas</span> chromatograph direct <span class="hlt">air</span> sampling procedure, and the GFCR data analysis procedure are reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AtmEn.119..220D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AtmEn.119..220D"><span>Seasonal variations in atmospheric <span class="hlt">concentrations</span> and <span class="hlt">gas</span>-particle partitioning of PCDD/Fs and dioxin-like PCBs around industrial sites in Shanghai, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Die, Qingqi; Nie, Zhiqiang; Liu, Feng; Tian, Yajun; Fang, Yanyan; Gao, Hefeng; Tian, Shulei; He, Jie; Huang, Qifei</p> <p>2015-10-01</p> <p><span class="hlt">Gas</span> and particle phase <span class="hlt">air</span> samples were collected in summer and winter around industrial sites in Shanghai, China, to allow the <span class="hlt">concentrations</span>, profiles, and <span class="hlt">gas</span>-particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) to be determined. The total 2,3,7,8-substituted PCDD/F and dl-PCB toxic equivalent (TEQ) <span class="hlt">concentrations</span> were 14.2-182 fg TEQ/m3 (mean 56.8 fg TEQ/m3) in summer and 21.9-479 fg TEQ/m3 (mean 145 fg TEQ/m3) in winter. The PCDD/Fs tended to be predominantly in the particulate phase, while the dl-PCBs were predominantly found in the <span class="hlt">gas</span> phase, and the proportions of all of the PCDD/F and dl-PCB congeners in the particle phase increased as the temperature decreased. The logarithms of the <span class="hlt">gas</span>-particle partition coefficients correlated well with the subcooled liquid vapor pressures of the PCDD/Fs and dl-PCBs for most of the samples. <span class="hlt">Gas</span>-particle partitioning of the PCDD/Fs deviated from equilibrium either in summer or winter close to local sources, and the Junge-Pankow model and predictions made using a model based on the octanol-<span class="hlt">air</span> partition coefficient fitted the measured particulate PCDD/F fractions well, indicating that absorption and adsorption mechanism both contributed to the partitioning process. However, <span class="hlt">gas</span>-particle equilibrium of the dl-PCBs was reached more easily in winter than in summer. The Junge-Pankow model predictions fitted the dl-PCB data better than did the predictions made using the model based on the octanol-<span class="hlt">air</span> partition coefficient, indicating that adsorption mechanism made dominated contribution to the partitioning process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26ES..104a2003N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26ES..104a2003N"><span>Turbine Inlet <span class="hlt">Air</span> Cooling for Industrial and Aero-derivative <span class="hlt">Gas</span> Turbine in Malaysia Climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nordin, A.; Salim, D. A.; Othoman, M. A.; Kamal, S. N. Omar; Tam, Danny; Yusof, M. KY</p> <p>2017-12-01</p> <p>The performance of a <span class="hlt">gas</span> turbine is dependent on the ambient temperature. A higher temperature results in a reduction of the <span class="hlt">gas</span> turbine’s power output and an increase in heat rate. The warm and humid climate in Malaysia with its high ambient <span class="hlt">air</span> temperature has an adverse effect on the performance of <span class="hlt">gas</span> turbine generators. In this paper, the expected effect of turbine inlet <span class="hlt">air</span> cooling technology on the annual performance of an aero-derivative <span class="hlt">gas</span> turbine (GE LM6000PD) is compared against that of an industrial <span class="hlt">gas</span> turbine (GEFr6B.03) using GT Pro software. This study investigated the annual net energy output and the annual net electrical efficiency of a plant with and without turbine inlet <span class="hlt">air</span> cooling technology. The results show that the aero-derivative <span class="hlt">gas</span> turbine responds more favorably to turbine inlet <span class="hlt">air</span> cooling technology, thereby yielding higher annual net energy output and higher net electrical efficiency when compared to the industrial <span class="hlt">gas</span> turbine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28664696','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28664696"><span>Human health cost of hydrogen sulfide <span class="hlt">air</span> pollution from an oil and <span class="hlt">gas</span> Field.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kenessary, Dinara; Kenessary, Almas; Kenessariyev, Ussen Ismailovich; Juszkiewicz, Konrad; Amrin, Meiram Kazievich; Erzhanova, Aya Eralovna</p> <p>2017-06-08</p> <p>Introduction and objective. The Karachaganak oil and <span class="hlt">gas</span> condensate field (KOGCF), one of the largest in the world, located in the Republic of Kazakhstan (RoK) in Central Asia, is surrounded by 10 settlements with a total population of 9,000 people. Approximately73% of this population constantly mention a specific odour of rotten eggs in the <span class="hlt">air</span>, typical for hydrogen sulfide (H<sub>2</sub>S) emissions, and the occurrence of low-level <span class="hlt">concentrations</span> of hydrogen sulfide around certain industrial installations (esp. oil refineries) is a well known fact. Therefore, this study aimed at determining the impact on human health and the economic damage to the country due to H<sub>2</sub>S emissions. Materials and method. Dose-response dependency between H<sub>2</sub>S <span class="hlt">concentrations</span> in the <span class="hlt">air</span> and cardiovascular morbidity using multiple regression analysis was applied. Economic damage from morbidity was derived with a newly-developed method, with Kazakhstani peculiarities taken into account. Results.Hydrogen sulfide <span class="hlt">air</span> pollution due to the KOGCF activity costs the state almost $60,000 per year. Moreover, this is the reason for a more than 40% rise incardiovascular morbidity in the region. Conclusion. The reduction of hydrogen sulfide emissions into the <span class="hlt">air</span> is recommended, as well as successive constant ambient <span class="hlt">air</span> monitoring in future. Economic damage evaluation should be made mandatory, on a legal basis, whenever an industrial facility operation results in associated <span class="hlt">air</span> pollution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JVGR..207..130C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JVGR..207..130C"><span>Diffuse CO 2 soil degassing and CO 2 and H 2S <span class="hlt">concentrations</span> in <span class="hlt">air</span> and related hazards at Vulcano Island (Aeolian arc, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carapezza, M. L.; Barberi, F.; Ranaldi, M.; Ricci, T.; Tarchini, L.; Barrancos, J.; Fischer, C.; Perez, N.; Weber, K.; Di Piazza, A.; Gattuso, A.</p> <p>2011-10-01</p> <p>La Fossa crater on Vulcano Island is quiescent since 1890. Periodically it undergoes "crises" characterized by marked increase of temperature (T), <span class="hlt">gas</span> output and <span class="hlt">concentration</span> of magmatic components in the crater fumaroles (T may exceed 600 °C). During these crises, which so far did not lead to any eruptive reactivation, the diffuse CO 2 soil degassing also increases and in December 2005 an anomalous CO 2 flux of 1350 tons/day was estimated by 1588 measurements over a surface of 1.66 km 2 extending from La Fossa crater to the inhabited zone of Vulcano Porto. The crater area and two other anomalously degassing sites (Levante Beach and Palizzi) have been periodically investigated from December 2004 to August 2010 for diffuse CO 2 soil flux. They show a marked variation with time of the degassing rate, with synchronous maxima in December 2005. Carbon dioxide soil flux and environmental parameters have been also continuously monitored for over one year by an automatic station at Vulcano Porto. In order to assess the hazard of the endogenous <span class="hlt">gas</span> emissions, CO 2 and H 2S <span class="hlt">air</span> <span class="hlt">concentrations</span> have been measured by Tunable Diode Laser profiles near the fumaroles of the crater rim and of the Levante Beach area, where also the viscous <span class="hlt">gas</span> flux has been estimated. In addition, CO 2 <span class="hlt">air</span> <span class="hlt">concentration</span> has been measured both indoor and outdoor in an inhabited sector of Vulcano Porto. Results show that in some sites usually frequented by tourists there is a dangerous H 2S <span class="hlt">air</span> <span class="hlt">concentration</span> and CO 2 exceeds the hazardous thresholds in some Vulcano houses. These zones should be immediately monitored for <span class="hlt">gas</span> hazard should a new crisis arise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/875029','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/875029"><span>Use of exhaust <span class="hlt">gas</span> as sweep flow to enhance <span class="hlt">air</span> separation membrane performance</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Dutart, Charles H.; Choi, Cathy Y.</p> <p>2003-01-01</p> <p>An intake <span class="hlt">air</span> separation system for an internal combustion engine is provided with purge <span class="hlt">gas</span> or sweep flow on the permeate side of separation membranes in the <span class="hlt">air</span> separation device. Exhaust <span class="hlt">gas</span> from the engine is used as a purge <span class="hlt">gas</span> flow, to increase oxygen flux in the separation device without increasing the nitrogen flux.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7073379-reduction-air-pollutant-concentrations-indoor-ice-skating-rink','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/7073379-reduction-air-pollutant-concentrations-indoor-ice-skating-rink"><span>Reduction of <span class="hlt">air</span> pollutant <span class="hlt">concentrations</span> in an indoor ice-skating rink</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lee, K.; Yanagisawa, Yukio; Spengler, J.D.</p> <p>1994-01-01</p> <p>High carbon monoxide and nitrogen dioxide <span class="hlt">concentrations</span> were measured in an indoor ice-skating rink with fuel-powered ice-resurfacing equipment. In 22% to 33% of the measurements over 90-min segments, CO <span class="hlt">concentrations</span> exceeded 20 [mu]L/L as a 90-min average in the absence of rink ventilation. Average NO[sub 2] <span class="hlt">concentrations</span> over 14 h were higher than 600 nL/L. Reduction of <span class="hlt">air</span> pollutant <span class="hlt">concentrations</span> in the ice-skating rink is necessary to prevent <span class="hlt">air</span>-pollutant-exposure-related health incidents. Various methods for reducing <span class="hlt">air</span> pollutants in an ice-skating rink were evaluated by simultaneously measuring CO and NO[sub 2] <span class="hlt">concentrations</span>. Single pollution reduction attempts, such as extension of themore » exhaust pipe, reduction in the number of resurfacer operations, or use of an <span class="hlt">air</span> recirculation system, did not significantly reduce <span class="hlt">air</span> pollutant <span class="hlt">concentrations</span> in the rink. Full operation of the mechanical ventilation system combined with reduced resurfacer operation was required to keep the <span class="hlt">air</span> pollutant levels in the skating rink below the recommended guidelines. This investigation showed that management of clean <span class="hlt">air</span> quality in an ice-skating rink is practically difficult as long as fuel-powered resurfacing equipment is used. 16 refs., 3 figs., 5 tabs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Th%26Ae..19..403K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Th%26Ae..19..403K"><span>Optimizing parameters of GTU cycle and design values of <span class="hlt">air-gas</span> channel in a <span class="hlt">gas</span> turbine with cooled nozzle and rotor blades</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kler, A. M.; Zakharov, Yu. B.</p> <p>2012-09-01</p> <p>The authors have formulated the problem of joint optimization of pressure and temperature of combustion products before <span class="hlt">gas</span> turbine, profiles of nozzle and rotor blades of <span class="hlt">gas</span> turbine, and cooling <span class="hlt">air</span> flow rates through nozzle and rotor blades. The article offers an original approach to optimization of profiles of <span class="hlt">gas</span> turbine blades where the optimized profiles are presented as linear combinations of preliminarily formed basic profiles. The given examples relate to optimization of the <span class="hlt">gas</span> turbine unit on the criterion of power efficiency at preliminary heat removal from <span class="hlt">air</span> flows supplied for the <span class="hlt">air-gas</span> channel cooling and without such removal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AtmEn.179..268P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AtmEn.179..268P"><span>Measurements of <span class="hlt">gas</span> and particle polycyclic aromatic hydrocarbons (PAHs) in <span class="hlt">air</span> at urban, rural and near-roadway sites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pratt, G. C.; Herbrandson, C.; Krause, M. J.; Schmitt, C.; Lippert, C. J.; McMahon, C. R.; Ellickson, K. M.</p> <p>2018-04-01</p> <p>We measured polycyclic aromatic hydrocarbons (PAHs) in <span class="hlt">gas</span> and particle phases over two years using high volume samplers equipped with quartz fiber filters and XAD-4 at a rural site, an urban site, and a site adjacent to a heavily trafficked roadway. Overall results were generally as expected, in that <span class="hlt">concentrations</span> increased from rural to urban to near-roadway sites, and PAHs with high vapor pressures (liquid subcooled, PoL) and low octanol-<span class="hlt">air</span> partition coefficients (Koa) were mainly in the <span class="hlt">gas</span> phase, while those with low PoL and high Koa were predominantly in the particle phase. Intermediate PAHs existed in both phases with the phase distribution following a seasonal pattern of higher <span class="hlt">gas</span> phase <span class="hlt">concentrations</span> in summer due to temperature effects. The overall pattern of phase distribution was consistent with PAH properties and ambient conditions and was similar at all three sites. The particle-bound fraction (ϕ) was well-described empirically by nonlinear regressions with log Koa and log PoL as predictors. Adsorption and absorption models underestimated the particle-bound fraction for most PAHs. The dual aerosol-<span class="hlt">air/soot-air</span> model generally represented the <span class="hlt">gas</span>-particle partitioning better than the other models across all PAHs, but there was a tendency to underestimate the range in the particle-bound fraction seen in measurements. There was a statistically insignificant tendency for higher PAHs in the particle phase at the near roadway site, and one piece of evidence that PAHs may be enriched on ultrafine particles at the near roadway site. Understanding the phase and particle size distributions of PAHs in highly polluted, high exposure microenvironments near traffic sources will help shed light on potential health effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AtmEn.147..320G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AtmEn.147..320G"><span>Determination of beryllium <span class="hlt">concentrations</span> in UK ambient <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goddard, Sharon L.; Brown, Richard J. C.; Ghatora, Baljit K.</p> <p>2016-12-01</p> <p><span class="hlt">Air</span> quality monitoring of ambient <span class="hlt">air</span> is essential to minimise the exposure of the general population to toxic substances such as heavy metals, and thus the health risks associated with them. In the UK, ambient <span class="hlt">air</span> is already monitored under the UK Heavy Metals Monitoring Network for a number of heavy metals, including nickel (Ni), arsenic (As), cadmium (Cd) and lead (Pb) to ensure compliance with legislative limits. However, the UK Expert Panel on <span class="hlt">Air</span> Quality Standards (EPAQS) has highlighted a need to limit <span class="hlt">concentrations</span> of beryllium (Be) in <span class="hlt">air</span>, which is not currently monitored, because of its toxicity. The aim of this work was to analyse airborne particulate matter (PM) sampled onto filter papers from the UK Heavy Metals Monitoring Network for quantitative, trace level beryllium determination and compare the results to the guideline <span class="hlt">concentration</span> specified by EPAQS. Samples were prepared by microwave acid digestion in a matrix of 2% sulphuric acid and 14% nitric acid, verified by the use of Certified Reference Materials (CRMs). The digested samples were then analysed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The filters from the UK Heavy Metals Monitoring Network were tested using this procedure and the average beryllium <span class="hlt">concentration</span> across the network for the duration of the study period was 7.87 pg m-3. The highest site average <span class="hlt">concentration</span> was 32.0 pg m-3 at Scunthorpe Low Santon, which is significantly lower than levels that are thought to cause harm. However the highest levels were observed at sites monitoring industrial point sources, indicating that beryllium is being used and emitted, albeit at very low levels, from these point sources. Comparison with other metals <span class="hlt">concentrations</span> and data from the UK National Atmospheric Emissions Inventory suggests that current emissions of beryllium may be significantly overestimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25606710','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25606710"><span>A multiyear assessment of <span class="hlt">air</span> quality benefits from China's emerging shale <span class="hlt">gas</span> revolution: Urumqi as a case study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Song, Wei; Chang, Yunhua; Liu, Xuejun; Li, Kaihui; Gong, Yanming; He, Guixiang; Wang, Xiaoli; Christie, Peter; Zheng, Mei; Dore, Anthony J; Tian, Changyan</p> <p>2015-02-17</p> <p>China is seeking to unlock its shale <span class="hlt">gas</span> in order to curb its notorious urban <span class="hlt">air</span> pollution, but robust assessment of the impact on PM2.5 pollution of replacing coal with natural <span class="hlt">gas</span> for winter heating is lacking. Here, using a whole-city heating energy shift opportunity offered by substantial reductions in coal combustion during the heating periods in Urumqi, northwest China, we conducted a four-year study to reveal the impact of replacing coal with natural <span class="hlt">gas</span> on the mass <span class="hlt">concentrations</span> and chemical components of PM2.5. We found a significant decline in PM2.5, major soluble ions and metal elements in PM2.5 in January of 2013 and 2014 compared with the same periods in 2012 and 2011, reflecting the positive effects on <span class="hlt">air</span> quality of using natural <span class="hlt">gas</span> as a heating fuel throughout the city. This occurred following complete replacement with natural <span class="hlt">gas</span> for heating energy in October 2012. The weather conditions during winter did not show any significant variation over the four years of the study. Our results indicate that China and other developing nations will benefit greatly from a change in energy source, that is, increasing the contribution of either natural <span class="hlt">gas</span> or shale <span class="hlt">gas</span> to total energy consumption with a concomitant reduction in coal consumption.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/4706702-survey-air-gas-cleaning-operations','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/4706702-survey-air-gas-cleaning-operations"><span>SURVEY OF <span class="hlt">AIR</span> AND <span class="hlt">GAS</span> CLEANING OPERATIONS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Morgenthaler, A.C.</p> <p>1959-09-01</p> <p>An informative summary of <span class="hlt">air</span> and <span class="hlt">gas</span> cleaning operations in the Chemicai Processing Department of the Hanfor Atomic Products Operation, Richland, Washington, is presented. Descriptlons of the fundamental components of cleaning systems, their applications, and cost information are included. (R.G.G.)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15683168','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15683168"><span><span class="hlt">Air</span>-water <span class="hlt">gas</span> exchange of chlorinated pesticides in four lakes spanning a 1,205 meter elevation range in the Canadian Rocky Mountains.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wilkinson, Andrew C; Kimpe, Lynda E; Blais, Jules M</p> <p>2005-01-01</p> <p><span class="hlt">Concentrations</span> of selected persistent organic pollutants (POPs) in <span class="hlt">air</span> and water were measured from four lakes that transect the Canadian Rocky Mountains. These data were used in combination with wind velocity and temperature-adjusted Henry's law constants to estimate the direction and magnitude of chemical exchange across the <span class="hlt">air</span>-water interface of these lakes. Bow Lake (1,975 m above sea level [masl]) was studied during the summers of 1998 through 2000; Donald (770 masl) was studied during the summer of 1999; Dixon Dam Lake (946 masl) and Kananaskis Lake (1,667 masl) were studied during the summer of 2000. Hexachlorobenzene (HCB) and dieldrin volatilized from Bow Lake in spring and summer of 1998 to 2000 at a rate of 0.92 +/-1.1 and 0.55+/-0.37 ng m(-2) d(-1), respectively. The alpha-endosulfan deposited to Bow Lake at a rate of 3.4+/-2.2 ng m(-2) d(-1). Direction of <span class="hlt">gas</span> exchange for gamma-hexachlorocyclohexane (gamma-HCH) changed from net deposition in 1998 to net volatilization in 1999, partly because of a surge in y-HCH <span class="hlt">concentrations</span> in the water at Bow Lake in 1999. Average gamma-HCH <span class="hlt">concentrations</span> in <span class="hlt">air</span> declined steadily over the three-year period, from 0.021 ng m(-3) in 1998, to 0.0023 ng m(-3) in 2000, and to volatilization in 1999 and 2000. Neither the <span class="hlt">concentrations</span> of organochlorine compounds (OCs) in <span class="hlt">air</span> and water, nor the direction and rate of <span class="hlt">air</span>-water <span class="hlt">gas</span> exchange correlate with temperature or elevation. In general, losses of pesticides by outflow were greater than the amount exchanged across the <span class="hlt">air</span>-water interface in these lakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry','PESTICIDES'); return false;" href="https://www.epa.gov/controlling-air-pollution-oil-and-natural-gas-industry"><span>Controlling <span class="hlt">Air</span> Pollution from the Oil and Natural <span class="hlt">Gas</span> Industry</span></a></p> <p><a target="_blank" href="http://www.epa.gov/pesticides/search.htm">EPA Pesticide Factsheets</a></p> <p></p> <p></p> <p>EPA regulations for the oil and natural <span class="hlt">gas</span> industry help combat climate change and reduce <span class="hlt">air</span> pollution that harms public health. EPA’s regulations apply to oil production, and the production, process, transmission and storage of natural <span class="hlt">gas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22788101','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22788101"><span>Review of Singapore's <span class="hlt">air</span> quality and greenhouse <span class="hlt">gas</span> emissions: current situation and opportunities.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Velasco, Erik; Roth, Matthias</p> <p>2012-06-01</p> <p>Singapore has many environmental accomplishments to its credit. Accessible data on <span class="hlt">air</span> quality indicates that all criteria pollutants satisfy both U.S. Environmental Protection Agency (EPA) and World Health Organization (WHO) <span class="hlt">air</span> quality standards and guidelines, respectively. The exception is PM2.5 (particles with an aerodynamic diameter < or = 2.5 microm), which is not currently considered a criteria pollutant in Singapore but may potentially be the major local <span class="hlt">air</span> pollution problem and cause for health concern. Levels of other airborne pollutants as well as their physical and chemical processes associated with local formation, transformation, dispersion, and deposition are not known. According to available emission inventories, Singapore contribution to the total atmospheric pollution and carbon budget at the regional and global scales is small. Emissions per unit gross domestic product (GDP) are low compared with other countries, although Singapore's per-capita GDP and per-capita emissions are among the highest in the world. Some information is available on health effects, but the impacts on the ecosystem and the complex interactions of <span class="hlt">air</span> pollution and climate change at a regional level are also unknown. This article reviews existing available information on atmospheric pollution and greenhouse <span class="hlt">gas</span> emissions and proposes a multipollutant approach to greenhouse <span class="hlt">gas</span> mitigation and local <span class="hlt">air</span> quality. Singapore, by reducing its per-capita emissions, increasing the availability of information (e.g., through regularly publishing hourly and/or daily PM2.5 <span class="hlt">concentrations</span>) and developing a research agenda in this area, would likely be seen to be a model of a high-density, livable, and sustainable city in Southeast Asia and other tropical regions worldwide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24661943','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24661943"><span>Brominated flame retardants in the urban atmosphere of Northeast China: <span class="hlt">concentrations</span>, temperature dependence and <span class="hlt">gas</span>-particle partitioning.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qi, Hong; Li, Wen-Long; Liu, Li-Yan; Song, Wei-Wei; Ma, Wan-Li; Li, Yi-Fan</p> <p>2014-09-01</p> <p>57 pairs of <span class="hlt">air</span> samples (<span class="hlt">gas</span> and particle phases) were collected using a high volume <span class="hlt">air</span> sampler in a typical city of Northeast China. Brominated flame retardants (BFRs) including 13 polybrominated diphenyl ethers (PBDEs, including BDEs 17, 28, 47, 49, 66, 85, 99, 100, 138, 153, 154, 183, and 209) and 9 alternative BFRs (p-TBX, PBBZ, PBT, PBEB, DPTE, HBBZ, γ-HBCD, BTBPE, and DBDPE) were analyzed. The annual average total <span class="hlt">concentrations</span> of the 13 PBDEs and the 9 alternative BFRs were 69 pg/m(3) and 180 pg/m(3), respectively. BDE 209 and γ-HBCD were the dominant congeners, according to the one-year study. The partial pressure of BFRs in the <span class="hlt">gas</span> phase was significantly correlated with the ambient temperature, except for BDE 85, γ-HBCD and DBDPE, indicating the important influence of ambient temperature on the behavior of BFRs in the atmosphere. It was found that the <span class="hlt">gas</span>-particle partitioning coefficients (logKp) for most low molecular weight BFRs were highly temperature dependent as well. <span class="hlt">Gas</span>-particle partitioning coefficients (logKp) also correlated with the sub-cooled liquid vapor pressure (logPL(o)). Our results indicated that absorption into organic matter is the main control mechanism for the <span class="hlt">gas</span>-particle partitioning of atmospheric PBDEs. Copyright © 2014 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..GECGT1142N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..GECGT1142N"><span>Open <span class="hlt">Air</span> Silicon Deposition by Atmospheric Pressure Plasma under Local Ambient <span class="hlt">Gas</span> Control</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa</p> <p>2015-09-01</p> <p>In this paper, we report open <span class="hlt">air</span> silicon (Si) deposition by combining a silane free Si deposition technology and a newly developed local ambient <span class="hlt">gas</span> control technology. Recently, material processing in open <span class="hlt">air</span> has been investigated intensively. While a variety of materials have been deposited, there were only few reports on Si deposition due to the susceptibility to contamination and the hazardous nature of source materials. Since Si deposition is one of the most important processes in device fabrication, we have developed open <span class="hlt">air</span> silicon deposition technologies in BEANS project. For a clean and safe process, a local ambient <span class="hlt">gas</span> control head was designed. Process <span class="hlt">gas</span> leakage was prevented by local evacuation, and <span class="hlt">air</span> contamination was shut out by inert curtain <span class="hlt">gas</span>. By numerical and experimental investigations, a safe and clean process condition with <span class="hlt">air</span> contamination less than 10 ppm was achieved. Si film was deposited in open <span class="hlt">air</span> by atmospheric pressure plasma enhanced chemical transport under the local ambient <span class="hlt">gas</span> control. The film was microcrystalline Si with the crystallite size of 17 nm, and the Hall mobility was 2.3 cm2/V .s. These properties were comparable to those of Si films deposited in a vacuum chamber. This research has been conducted as one of the research items of New Energy and Industrial Technology Development Organization ``BEANS'' project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4909253','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4909253"><span>Home interventions are effective at decreasing indoor nitrogen dioxide <span class="hlt">concentrations</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Paulin, L. M.; Diette, G. B.; Scott, M.; McCormack, M. C.; Matsui, E. C.; Curtin-Brosnan, J.; Williams, D. L.; Kidd-Taylor, A.; Shea, M.; Breysse, P. N.; Hansel, N. N.</p> <p>2016-01-01</p> <p>Nitrogen dioxide (NO2), a by-product of combustion produced by indoor <span class="hlt">gas</span> appliances such as cooking stoves, is associated with respiratory symptoms in those with obstructive airways disease. We conducted a three-armed randomized trial to evaluate the efficacy of interventions aimed at reducing indoor NO2 <span class="hlt">concentrations</span> in homes with unvented <span class="hlt">gas</span> stoves: (i) replacement of existing <span class="hlt">gas</span> stove with electric stove; (ii) installation of ventilation hood over existing <span class="hlt">gas</span> stove; and (iii) placement of <span class="hlt">air</span> purifiers with high-efficiency particulate <span class="hlt">air</span> (HEPA) and carbon filters. Home inspection and NO2 monitoring were conducted at 1 week pre-intervention and at 1 week and 3 months post-intervention. Stove replacement resulted in a 51% and 42% decrease in median NO2 <span class="hlt">concentration</span> at 3 months of follow-up in the kitchen and bedroom, respectively (P = 0.01, P = 0.01); <span class="hlt">air</span> purifier placement resulted in an immediate decrease in median NO2 <span class="hlt">concentration</span> in the kitchen (27%, P < 0.01) and bedroom (22%, P = 0.02), but at 3 months, a significant reduction was seen only in the kitchen (20%, P = 0.05). NO2 <span class="hlt">concentrations</span> in the kitchen and bedroom did not significantly change following ventilation hood installation. Replacing unvented <span class="hlt">gas</span> stoves with electric stoves or placement of <span class="hlt">air</span> purifiers with HEPA and carbon filters can decrease indoor NO2 <span class="hlt">concentrations</span> in urban homes. PMID:24329966</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol28/pdf/CFR-2013-title40-vol28-part266-appIV.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol28/pdf/CFR-2013-title40-vol28-part266-appIV.pdf"><span>40 CFR Appendix IV to Part 266 - Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>*</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 40 Protection of Environment 28 2013-07-01 2013-07-01 false Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>* IV Appendix IV to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES... MANAGEMENT FACILITIES Pt. 266, App. IV Appendix IV to Part 266—Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>* Constituent CAS...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol27/pdf/CFR-2014-title40-vol27-part266-appIV.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol27/pdf/CFR-2014-title40-vol27-part266-appIV.pdf"><span>40 CFR Appendix IV to Part 266 - Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>*</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 40 Protection of Environment 27 2014-07-01 2014-07-01 false Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>* IV Appendix IV to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES... MANAGEMENT FACILITIES Pt. 266, App. IV Appendix IV to Part 266—Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>* Constituent CAS...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol27/pdf/CFR-2011-title40-vol27-part266-appIV.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol27/pdf/CFR-2011-title40-vol27-part266-appIV.pdf"><span>40 CFR Appendix IV to Part 266 - Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>*</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 40 Protection of Environment 27 2011-07-01 2011-07-01 false Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>* IV Appendix IV to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES... MANAGEMENT FACILITIES Pt. 266, App. IV Appendix IV to Part 266—Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>* Constituent CAS...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol26/pdf/CFR-2010-title40-vol26-part266-appIV.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol26/pdf/CFR-2010-title40-vol26-part266-appIV.pdf"><span>40 CFR Appendix IV to Part 266 - Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>*</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>* IV Appendix IV to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES... MANAGEMENT FACILITIES Pt. 266, App. IV Appendix IV to Part 266—Reference <span class="hlt">Air</span> <span class="hlt">Concentrations</span>* Constituent CAS...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24974151','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24974151"><span>Mercury <span class="hlt">concentrations</span> and distribution in soil, water, mine waste leachates, and <span class="hlt">air</span> in and around mercury mines in the Big Bend region, Texas, USA.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gray, John E; Theodorakos, Peter M; Fey, David L; Krabbenhoft, David P</p> <p>2015-02-01</p> <p>Samples of soil, water, mine waste leachates, soil <span class="hlt">gas</span>, and <span class="hlt">air</span> were collected from areas mined for mercury (Hg) and baseline sites in the Big Bend area, Texas, to evaluate potential Hg contamination in the region. Soil samples collected within 300 m of an inactive Hg mine contained elevated Hg <span class="hlt">concentrations</span> (3.8-11 µg/g), which were considerably higher than Hg in soil collected from baseline sites (0.03-0.05 µg/g) distal (as much as 24 km) from mines. Only three soil samples collected within 300 m of the mine exceeded the probable effect <span class="hlt">concentration</span> for Hg of 1.06 µg/g, above which harmful effects are likely to be observed in sediment-dwelling organisms. <span class="hlt">Concentrations</span> of Hg in mine water runoff (7.9-14 ng/L) were generally higher than those found in springs and wells (0.05-3.1 ng/L), baseline streams (1.1-9.7 ng/L), and sources of drinking water (0.63-9.1 ng/L) collected in the Big Bend region. <span class="hlt">Concentrations</span> of Hg in all water samples collected in this study were considerably below the 2,000 ng/L drinking water Hg guideline and the 770 ng/L guideline recommended by the U.S. Environmental Protection Agency (USEPA) to protect aquatic wildlife from chronic effects of Hg. <span class="hlt">Concentrations</span> of Hg in water leachates obtained from leaching of mine wastes varied widely from <0.001 to 760 µg of Hg in leachate/g of sample leached, but only one leachate exceeded the USEPA Hg industrial soil screening level of 31 µg/g. <span class="hlt">Concentrations</span> of Hg in soil <span class="hlt">gas</span> collected at mined sites (690-82,000 ng/m(3)) were highly elevated compared to soil <span class="hlt">gas</span> collected from baseline sites (1.2-77 ng/m(3)). However, <span class="hlt">air</span> collected from mined areas at a height of 2 m above the ground surface contained <span class="hlt">concentrations</span> of Hg (4.9-64 ng/m(3)) that were considerably lower than Hg in soil <span class="hlt">gas</span> from the mined areas. Although <span class="hlt">concentrations</span> of Hg emitted from mine-contaminated soils and mine wastes were elevated, persistent wind in southwest Texas disperses Hg in the <span class="hlt">air</span> within a few meters of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870016993','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870016993"><span>The <span class="hlt">Air</span> Force <span class="hlt">concentrating</span> photovoltaic array program</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Geis, Jack W.</p> <p>1987-01-01</p> <p>A summary is given of <span class="hlt">Air</span> Force solar <span class="hlt">concentrator</span> projects beginning with the Rockwell International study program in 1977. The Satellite Materials Hardening Programs (SMATH) explored and developed techniques for hardening planar solar cell array power systems to the combined nuclear and laser radiation threat environments. A portion of program dollars was devoted to developing a preliminary design for a hardened solar <span class="hlt">concentrator</span>. The results of the Survivable <span class="hlt">Concentrating</span> Photovoltaic Array (SCOPA) program, and the design, fabrication and flight qualification of a hardened <span class="hlt">concentrator</span> panel are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29040116','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29040116"><span><span class="hlt">Air</span> Versus Sulfur Hexafluoride <span class="hlt">Gas</span> Tamponade in Descemet Membrane Endothelial Keratoplasty: A Fellow Eye Comparison.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>von Marchtaler, Philipp V; Weller, Julia M; Kruse, Friedrich E; Tourtas, Theofilos</p> <p>2018-01-01</p> <p>To perform a fellow eye comparison of outcomes and complications when using <span class="hlt">air</span> or sulfur hexafluoride (SF6) <span class="hlt">gas</span> as a tamponade in Descemet membrane endothelial keratoplasty (DMEK). One hundred thirty-six eyes of 68 consecutive patients who underwent uneventful DMEK in both eyes for Fuchs endothelial corneal dystrophy were included in this retrospective study. Inclusion criteria were <span class="hlt">air</span> tamponade (80% of the anterior chamber volume) in the first eye and 20% SF6 <span class="hlt">gas</span> tamponade (80% of the anterior chamber volume) in the second eye; and same donor tissue culture condition in both eyes. All eyes received laser iridotomy on the day before DMEK. Main outcome measures included preoperative and postoperative best-corrected visual acuity, endothelial cell density, corneal volume, rebubbling rate, and rate of postoperative pupillary block caused by the <span class="hlt">air/gas</span> bubble. Thirteen of 68 eyes (19.1%) with an <span class="hlt">air</span> tamponade needed rebubbling compared with 4 of 68 eyes (5.9%) with an SF6 <span class="hlt">gas</span> tamponade (P = 0.036). Postoperative pupillary block necessitating partial release of <span class="hlt">air/gas</span> occurred in 1 eye (1.5%) with an <span class="hlt">air</span> tamponade and 3 eyes (4.4%) with an SF6 <span class="hlt">gas</span> tamponade (P = 0.301). There were no significant differences in preoperative and postoperative best-corrected visual acuity, endothelial cell density, and corneal volume within 3-month follow-up. Our results confirm the previously reported better graft adhesion when using an SF6 <span class="hlt">gas</span> tamponade in DMEK without increased endothelial cell toxicity. The rate of pupillary block in eyes with an SF6 <span class="hlt">gas</span> tamponade was comparable to that with an <span class="hlt">air</span> tamponade. As a consequence, we recommend using SF6 <span class="hlt">gas</span> as the tamponade in DMEK.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994ATJEG.116..360D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994ATJEG.116..360D"><span>Performance and economic enhancement of cogeneration <span class="hlt">gas</span> turbines through compressor inlet <span class="hlt">air</span> cooling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Delucia, M.; Bronconi, R.; Carnevale, E.</p> <p>1994-04-01</p> <p><span class="hlt">Gas</span> turbine <span class="hlt">air</span> cooling systems serve to raise performance to peak power levels during the hot months when high atmospheric temperatures cause reductions in net power output. This work describes the technical and economic advantages of providing a compressor inlet <span class="hlt">air</span> cooling system to increase the <span class="hlt">gas</span> turbine's power rating and reduce its heat rate. The pros and cons of state-of-the-art cooling technologies, i.e., absorption and compression refrigeration, with and without thermal energy storage, were examined in order to select the most suitable cooling solution. Heavy-duty <span class="hlt">gas</span> turbine cogeneration systems with and without absorption units were modeled, as well as various industrial sectors, i.e., paper and pulp, pharmaceuticals, food processing, textiles, tanning, and building materials. The ambient temperature variations were modeled so the effects of climate could be accounted for in the simulation. The results validated the advantages of <span class="hlt">gas</span> turbine cogeneration with absorption <span class="hlt">air</span> cooling as compared to other systems without <span class="hlt">air</span> cooling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28375266','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28375266"><span>Minimum detectable <span class="hlt">gas</span> <span class="hlt">concentration</span> performance evaluation method for <span class="hlt">gas</span> leak infrared imaging detection systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Xu; Jin, Weiqi; Li, Jiakun; Wang, Xia; Li, Shuo</p> <p>2017-04-01</p> <p>Thermal imaging technology is an effective means of detecting hazardous <span class="hlt">gas</span> leaks. Much attention has been paid to evaluation of the performance of <span class="hlt">gas</span> leak infrared imaging detection systems due to several potential applications. The minimum resolvable temperature difference (MRTD) and the minimum detectable temperature difference (MDTD) are commonly used as the main indicators of thermal imaging system performance. This paper establishes a minimum detectable <span class="hlt">gas</span> <span class="hlt">concentration</span> (MDGC) performance evaluation model based on the definition and derivation of MDTD. We proposed the direct calculation and equivalent calculation method of MDGC based on the MDTD measurement system. We build an experimental MDGC measurement system, which indicates the MDGC model can describe the detection performance of a thermal imaging system to typical gases. The direct calculation, equivalent calculation, and direct measurement results are consistent. The MDGC and the minimum resolvable <span class="hlt">gas</span> <span class="hlt">concentration</span> (MRGC) model can effectively describe the performance of "detection" and "spatial detail resolution" of thermal imaging systems to <span class="hlt">gas</span> leak, respectively, and constitute the main performance indicators of <span class="hlt">gas</span> leak detection systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980Tell...32..470H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980Tell...32..470H"><span><span class="hlt">Gas</span> exchange across the <span class="hlt">air</span>-sea interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasse, L.; Liss, P. S.</p> <p>1980-10-01</p> <p>The physics of <span class="hlt">gas</span> exchange at the <span class="hlt">air</span>-sea interface are reviewed. In order to describe the transfer of gases in the liquid near the boundary, a molecular plus eddy diffusivity concept is used, which has been found useful for smooth flow over solid surfaces. From consideration of the boundary conditions, a similar dependence of eddy diffusivity on distance from the interface can be derived for the flow beneath a <span class="hlt">gas</span>/liquid interface, at least in the absence of waves. The influence of waves is then discussed. It is evident from scale considerations that the effect of gravity waves is small. It is known from wind tunnel work that capillary waves enhance <span class="hlt">gas</span> transfer considerably. The existing hypotheses are apparently not sufficient to explain the observations. Examination of field data is even more frustrating since the data do not show the expected increase of <span class="hlt">gas</span> exchange with wind speed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23684023','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23684023"><span>Effects of <span class="hlt">gas</span> composition in headspace and bicarbonate <span class="hlt">concentrations</span> in media on <span class="hlt">gas</span> and methane production, degradability, and rumen fermentation using in vitro <span class="hlt">gas</span> production techniques.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Patra, Amlan Kumar; Yu, Zhongtang</p> <p>2013-07-01</p> <p>Headspace <span class="hlt">gas</span> composition and bicarbonate <span class="hlt">concentrations</span> in media can affect methane production and other characteristics of rumen fermentation in in vitro <span class="hlt">gas</span> production systems, but these 2 important factors have not been evaluated systematically. In this study, these 2 factors were investigated with respect to <span class="hlt">gas</span> and methane production, in vitro digestibility of feed substrate, and volatile fatty acid (VFA) profile using in vitro <span class="hlt">gas</span> production techniques. Three headspace <span class="hlt">gas</span> compositions (N2+ CO2+ H2 in the ratio of 90:5:5, CO2, and N2) with 2 substrate types (alfalfa hay only, and alfalfa hay and a <span class="hlt">concentrate</span> mixture in a 50:50 ratio) in a 3×2 factorial design (experiment 1) and 3 headspace compositions (N2, N2 + CO2 in a 50:50 ratio, and CO2) with 3 bicarbonate <span class="hlt">concentrations</span> (80, 100, and 120 mM) in a 3×3 factorial design (experiment 2) were evaluated. In experiment 1, total <span class="hlt">gas</span> production (TGP) and net <span class="hlt">gas</span> production (NGP) was the lowest for CO2, followed by N2, and then the <span class="hlt">gas</span> mixture. Methane <span class="hlt">concentration</span> in headspace <span class="hlt">gas</span> after fermentation was greater for CO2 than for N2 and the <span class="hlt">gas</span> mixture, whereas total methane production (TMP) and net methane production (NMP) were the greatest for CO2, followed by the <span class="hlt">gas</span> mixture, and then N2. Headspace composition did not affect in vitro digestibility or the VFA profile, except molar percentages of propionate, which were greater for CO2 and N2 than for the <span class="hlt">gas</span> mixture. Methane <span class="hlt">concentration</span> in headspace <span class="hlt">gas</span>, TGP, and NGP were affected by the interaction of headspace <span class="hlt">gas</span> composition and substrate type. In experiment 2, increasing <span class="hlt">concentrations</span> of CO2 in the headspace decreased TGP and NGP quadratically, but increased the <span class="hlt">concentrations</span> of methane, NMP, and in vitro fiber digestibility linearly, and TMP quadratically. Fiber digestibility, TGP, and NGP increased linearly with increasing bicarbonate <span class="hlt">concentrations</span> in the medium. <span class="hlt">Concentrations</span> of methane and NMP were unaffected by bicarbonate <span class="hlt">concentration</span>, but</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..225a2134C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..225a2134C"><span>Sustainable Solution for Crude Oil and Natural <span class="hlt">Gas</span> Separation using <span class="hlt">Concentrated</span> Solar Power Technology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choudhary, Piyush; Srivastava, Rakesh K.; Nath Mahendra, Som; Motahhir, Saad</p> <p>2017-08-01</p> <p>In today’s scenario to combat with climate change effects, there are a lot of reasons why we all should use renewable energy sources instead of fossil fuels. Solar energy is one of the best options based on features like good for the environment, independent of electricity prices, underutilized land, grid security, sustainable growth, etc. This concept paper is oriented primarily focused on the use of Solar Energy for the crude oil heating purpose besides other many prospective industrial applications to reduce cost, carbon footprint and moving towards a sustainable and ecologically friendly Oil & <span class="hlt">Gas</span> Industry. <span class="hlt">Concentrated</span> Solar Power technology based prototype system is proposed to substitute the presently used system based on natural <span class="hlt">gas</span> burning method. The hybrid system which utilizes the solar energy in the oil and <span class="hlt">gas</span> industry would strengthen the overall field working conditions, safety measures and environmental ecology. 40% reduction on natural <span class="hlt">gas</span> with this hybrid system is estimated. A positive implication for an environment, working conditions and safety precautions is the additive advantage. There could also decrease <span class="hlt">air</span> venting of CO2, CH4 and N2O by an average of 30-35%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/755820-measurements-alkali-concentrations-oxygen-natural-gas-fired-soda-lime-silica-glass-furnace','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/755820-measurements-alkali-concentrations-oxygen-natural-gas-fired-soda-lime-silica-glass-furnace"><span>Measurements of alkali <span class="hlt">concentrations</span> in an oxygen-natural <span class="hlt">gas</span>-fired soda-lime-silica glass furnace</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>S. G. Buckley; P. M. Walsh; D. w. Hahn</p> <p>1999-10-18</p> <p>Sodium species vaporized from melting batch and molten glass in tank furnaces are the principal agents of corrosion of superstructure refractory and main contributors to emissions of particulate matter from glass melting. The use of oxygen in place of <span class="hlt">air</span> for combustion of natural <span class="hlt">gas</span> reduces particulate emissions, but is thought to accelerate corrosion in some melting tanks. Methods for measuring sodium are under investigation as means for identifying the volatilization, transport, and deposition mechanisms and developing strategies for control. Three separate methods were used to measure the <span class="hlt">concentrations</span> of sodium species at various locations in an oxygen-natural <span class="hlt">gas</span>-fired soda-lime-silicamore » glass melting tank. Measurements were made inside the furnace using the absorption of visible light and in the flue duct using Laser-Induced Breakdown Spectroscopy (LIBS). Measurements in both the furnace and flue were also made by withdrawing and analyzing samples of the furnace <span class="hlt">gas</span>.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACPD...1530959A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACPD...1530959A"><span>Contribution of ship emissions to the <span class="hlt">concentration</span> and deposition of <span class="hlt">air</span> pollutants in Europe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aksoyoglu, S.; Prévôt, A. S. H.; Baltensperger, U.</p> <p>2015-11-01</p> <p>Emissions from the marine transport sector are one of the least regulated anthropogenic emission sources and contribute significantly to <span class="hlt">air</span> pollution. Although strict limits were introduced recently for the maximum sulfur content in marine fuels in the SECAs (sulfur emission control areas) and in the EU ports, sulfur emissions outside the SECAs and emissions of other components in all European maritime areas have continued to increase in the last two decades. We have used the <span class="hlt">air</span> quality model CAMx with and without ship emissions for the year 2006 to determine the effects of international shipping on the annual as well as seasonal <span class="hlt">concentrations</span> of ozone, primary and secondary components of PM2.5 and the dry and wet deposition of nitrogen and sulfur compounds in Europe. Our results suggest that emissions from international shipping affect the <span class="hlt">air</span> quality in northern and southern Europe differently and their contributions to the <span class="hlt">air</span> <span class="hlt">concentrations</span> vary seasonally. The largest changes in pollutant <span class="hlt">concentrations</span> due to ship emissions were predicted for summer. Increased <span class="hlt">concentrations</span> of the primary particle mass were found only along the shipping routes whereas <span class="hlt">concentrations</span> of the secondary pollutants were affected over a larger area. <span class="hlt">Concentrations</span> of particulate sulfate increased due to ship emissions in the Mediterranean (up to 60 %), in the English Channel and the North Sea (30-35 %) while increases in particulate nitrate levels were found especially in the north, around the Benelux area (20 %) where there were high NH3 land-based emissions. Our model results showed that not only the atmospheric <span class="hlt">concentrations</span> of pollutants are affected by ship emissions, but also depositions of nitrogen and sulfur compounds increase significantly along the shipping routes. NOx emissions from the ships especially in the English Channel and the North Sea, cause a decrease in the dry deposition of reduced nitrogen at source regions by moving it from the <span class="hlt">gas</span>-phase to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8355G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8355G"><span>A new portable generator to dynamically produce SI-traceable reference <span class="hlt">gas</span> mixtures for VOCs and water vapour at atmospheric <span class="hlt">concentration</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guillevic, Myriam; Pascale, Céline; Ackermann, Andreas; Leuenberger, Daiana; Niederhauser, Bernhard</p> <p>2016-04-01</p> <p>In the framework of the KEY-VOCs and AtmoChem-ECV projects, we are currently developing new facilities to dynamically generate reference <span class="hlt">gas</span> mixtures for a variety of reactive compounds, at <span class="hlt">concentrations</span> measured in the atmosphere and in a SI-traceable way (i.e. the amount of substance fraction in mole per mole is traceable to SI-units). Here we present the realisation of such standards for water vapour in the range 1-10 μmol/mol and for volatile organic compounds (VOCs) such as limonene, alpha-pinene, MVK, MEK, in the nmol/mol range. The matrix <span class="hlt">gas</span> can be nitrogen or synthetic <span class="hlt">air</span>. Further development in <span class="hlt">gas</span> purification techniques could make possible to use purified atmospheric <span class="hlt">air</span> as carrier <span class="hlt">gas</span>. The method is based on permeation and dynamic dilution: one permeator containing a pure substance (either water, limonene, MVK, MEK or α-pinene) is kept into a permeation chamber with a constant <span class="hlt">gas</span> flow. The mass loss is precisely calibrated using a magnetic suspension balance. The carrier <span class="hlt">gas</span> is purified beforehand from the compounds of interest to the required level, using commercially available purification cartridges. This primary mixture is then diluted to reach the required amount of substance fraction. All flows are piloted by mass flow controllers which makes the production process flexible and easily adaptable to generate the required <span class="hlt">concentration</span>. All parts in contact with the <span class="hlt">gas</span> mixture are passivated using coated surfaces, to reduce adsorption/desorption processes as much as possible. Two setups are currently developed: one already built and fixed in our laboratory in Bern as well as a portable generator that is still under construction and that could be used anywhere in the field. The permeation chamber of the portable generator has multiple individual cells allowing the generation of mixtures up to 5 different components if needed. Moreover the presented technique can be adapted and applied to a large variety of molecules (e.g., NO2, BTEX, CFCs</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AtmEn.131..279U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AtmEn.131..279U"><span><span class="hlt">Gas</span>-phase naphthalene <span class="hlt">concentration</span> data recovery in ambient <span class="hlt">air</span> and its relevance as a tracer of sources of volatile organic compounds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Uria-Tellaetxe, Iratxe; Navazo, Marino; de Blas, Maite; Durana, Nieves; Alonso, Lucio; Iza, Jon</p> <p>2016-04-01</p> <p>Despite the toxicity of naphthalene and the fact that it is a precursor of atmospheric photooxidants and secondary aerosol, studies on ambient <span class="hlt">gas</span>-phase naphthalene are generally scarce. Moreover, as far as we are concerned, this is the first published one using long-term hourly ambient <span class="hlt">gas</span>-phase naphthalene <span class="hlt">concentrations</span>. In this work, it has been also demonstrated the usefulness of ambient <span class="hlt">gas</span>-phase naphthalene to identify major sources of volatile organic compounds (VOC) in complex scenarios. Initially, in order to identify main benzene emission sources, hourly ambient measurements of 60 VOC were taken during a complete year together with meteorological data in an urban/industrial area. Later, due to the observed co-linearity of some of the emissions, a procedure was developed to recover naphthalene <span class="hlt">concentration</span> data from recorded chromatograms to use it as a tracer of the combustion and distillation of petroleum products. The characteristic retention time of this compound was determined comparing previous GC-MS and GC-FID simultaneous analysis by means of relative retention times, and its <span class="hlt">concentration</span> was calculated by using relative response factors. The obtained naphthalene <span class="hlt">concentrations</span> correlated fairly well with ethene (r = 0.86) and benzene (r = 0.92). Besides, the analysis of daily time series showed that these compounds followed a similar pattern, very different from that of other VOC, with minimum <span class="hlt">concentrations</span> at day-time. This, together with the results from the assessment of the meteorological dependence pointed out a coke oven as the major naphthalene and benzene emitting sources in the study area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12608592','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12608592"><span>Leukotriene-B4 <span class="hlt">concentrations</span> in exhaled breath condensate and lung function after thirty minutes of breathing technically dried compressed <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Neubauer, Birger; Struck, Niclas; Mutzbauer, Till S; Schotte, Ulrich; Langfeldt, Norbert; Tetzlaff, Kay</p> <p>2002-01-01</p> <p>In previous studies it had been shown that leukotriene-B4 [LTB4] <span class="hlt">concentrations</span> in the exhaled breath mirror the inflammatory activity of the airways if the respiratory tract has been exposed to occupational hazards. In diving the respiratory tract is exposed to cold and dry <span class="hlt">air</span> and the nasopharynx, as the site of breathing-<span class="hlt">gas</span> warming and humidification, is bypassed. The aim of the present study was to obtain LTB4-<span class="hlt">concentrations</span> in the exhaled breath and spirometric data of 17 healthy subjects before and after thirty minutes of technically dried <span class="hlt">air</span> breathing at normobar ambient pressure. The exhaled breath was collected non-invasively, via a permanently cooled expiration tube. The condensate was measured by a standard enzyme immunoassay for LTB4. Lung function values (FVC, FEV1, MEF 25, MEF 50) were simultaneously obtained by spirometry. The measured pre- and post-exposure LTB4- <span class="hlt">concentrations</span> as well as the lung function values were in the normal range. The present data gave no evidence for any inflammatory activity in the subjects' airways after thirty minutes breathing technically dried <span class="hlt">air</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080008673','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080008673"><span>Fuel-<span class="hlt">air</span> mixing apparatus for reducing <span class="hlt">gas</span> turbine combustor exhaust emissions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zupanc, Frank J. (Inventor); Yankowich, Paul R. (Inventor)</p> <p>2006-01-01</p> <p>A fuel-<span class="hlt">air</span> mixer for use in a combustion chamber of a <span class="hlt">gas</span> turbine engine is provided. The fuel <span class="hlt">air</span> mixing apparatus comprises an annular fuel injector having a plurality of discrete plain jet orifices, a first swirler wherein the first swirler is located upstream from the fuel injector and a second swirler wherein the second swirler is located downstream from the fuel injector. The plurality of discrete plain jet orifices are situated between the highly swirling airstreams generated by the two radial swirlers. The distributed injection of the fuel between two highly swirling airstreams results in rapid and effective mixing to the desired fuel-<span class="hlt">air</span> ratio and prevents the formation of local hot spots in the combustor primary zone. A combustor and a <span class="hlt">gas</span> turbine engine comprising the fuel-<span class="hlt">air</span> mixer of the present invention are also provided as well as a method using the fuel-<span class="hlt">air</span> mixer of the present invention.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22868345','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22868345"><span>Summer-winter <span class="hlt">concentrations</span> and <span class="hlt">gas</span>-particle partitioning of short chain chlorinated paraffins in the atmosphere of an urban setting.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Thanh; Han, Shanlong; Yuan, Bo; Zeng, Lixi; Li, Yingming; Wang, Yawei; Jiang, Guibin</p> <p>2012-12-01</p> <p>Short chain chlorinated paraffins (SCCPs) are semi-volatile chemicals that are considered persistent in the environment, potential toxic and subject to long-range transport. This study investigates the <span class="hlt">concentrations</span> and <span class="hlt">gas</span>-particle partitioning of SCCPs at an urban site in Beijing during summer and wintertime. The total atmospheric SCCP levels ranged 1.9-33.0 ng/m(3) during wintertime. Significantly higher levels were found during the summer (range 112-332 ng/m(3)). The average fraction of total SCCPs in the particle phase (ϕ) was 0.67 during wintertime but decreased significantly during the summer (ϕ = 0.06). The ten and eleven carbon chain homologues with five to eight chlorine atoms were the predominant SCCP formula groups in <span class="hlt">air</span>. Significant linear correlations were found between the <span class="hlt">gas</span>-particle partition coefficients and the predicted subcooled vapor pressures and octanol-<span class="hlt">air</span> partition coefficients. The <span class="hlt">gas</span>-particle partitioning of SCCPs was further investigated and compared with both the Junge-Pankow adsorption and K(oa)-based absorption models. Copyright © 2012 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27763773','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27763773"><span>High <span class="hlt">Concentrations</span> of Ozone <span class="hlt">Air</span> Pollution on Mount Everest: Health Implications for Sherpa Communities and Mountaineers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Semple, John L; Moore, G W Kent; Koutrakis, Petros; Wolfson, Jack M; Cristofanelli, Paolo; Bonasoni, Paolo</p> <p>2016-12-01</p> <p>Semple, John L., G.W. Kent Moore, Petros Koutrakis, Jack M. Wolfson, Paolo Cristofanelli, and Paolo Bonasoni. High <span class="hlt">concentrations</span> of ozone <span class="hlt">air</span> pollution on Mount Everest: health implications for Sherpa communities and mountaineers. High Alt Med Biol. 17:365-369, 2016.-Introduction: Populations in remote mountain regions are increasingly vulnerable to multiple climate mechanisms that influence levels of <span class="hlt">air</span> pollution. Few studies have reported on climate-sensitive health outcomes unique to high altitude ecosystems. In this study, we report on the discovery of high-surface ozone <span class="hlt">concentrations</span> and the potential impact on health outcomes on Mount Everest and the high Himalaya. Surface ozone measurements were collected during ascending transects in the Mount Everest region of Nepal with passive nitrite-coated Ogawa filter samplers to obtain 8-hour personal exposures (2860-5364 m asl). In addition, the Nepal Climate Observatory-Pyramid, a GAW-WMO Global Station sited in the Khumbu Valley (5079 m asl), collected ozone mixing ratios with photometric <span class="hlt">gas</span> analyzer. Surface ozone measurements increased with altitude with <span class="hlt">concentrations</span> that exceed 100 ppb (8-hour exposure). Highest values were during the spring season and the result of diverse contributions: hemispheric background values, the descent of ozone-rich stratospheric <span class="hlt">air</span>, and the transport of tropospheric pollutants occurring at different spatial scales. Multiple climate factors, including descending stratospheric ozone and imported anthropogenic <span class="hlt">air</span> masses from the Indo-Gangetic Plain, contribute to ambient ozone exposure levels in the vicinity of Mount Everest that are similar to if not higher than those reported in industrialized cities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27..874S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27..874S"><span>Observational Studies of Parameters Influencing <span class="hlt">Air</span>-sea <span class="hlt">Gas</span> Exchange</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schimpf, U.; Frew, N. M.; Bock, E. J.; Hara, T.; Garbe, C. S.; Jaehne, B.</p> <p></p> <p>A physically-based modeling of the <span class="hlt">air</span>-sea <span class="hlt">gas</span> transfer that can be used to predict the <span class="hlt">gas</span> transfer rates with sufficient accuracy as a function of micrometeorological parameters is still lacking. State of the art are still simple <span class="hlt">gas</span> transfer rate/wind speed relationships. Previous measurements from Coastal Ocean Experiment in the Atlantic revealed positive correlations between mean square slope, near surface turbulent dis- sipation, and wind stress. It also demonstrated a strong negative correlation between mean square slope and the fluorescence of surface-enriched colored dissolved organic matter. Using heat as a proxy tracer for gases the exchange process at the <span class="hlt">air</span>/water interface and the micro turbulence at the water surface can be investigated. The anal- ysis of infrared image sequences allow the determination of the net heat flux at the ocean surface, the temperature gradient across the <span class="hlt">air</span>/sea interface and thus the heat transfer velocity and <span class="hlt">gas</span> transfer velocity respectively. Laboratory studies were carried out in the new Heidelberg wind-wave facility AELOTRON. Direct measurements of the Schmidt number exponent were done in conjunction with classical mass balance methods to estimate the transfer velocity. The laboratory results allowed to validate the basic assumptions of the so called controlled flux technique by applying differ- ent tracers for the <span class="hlt">gas</span> exchange in a large Schmidt number regime. Thus a modeling of the Schmidt number exponent is able to fill the gap between laboratory and field measurements field. Both, the results from the laboratory and the field measurements should be able to give a further understanding of the mechanisms controlling the trans- port processes across the aqueous boundary layer and to relate the forcing functions to parameters measured by remote sensing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A43G2558W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A43G2558W"><span><span class="hlt">Air</span>-sea exchange and <span class="hlt">gas</span>-particle partitioning of polycyclic aromatic hydrocarbons over the northwestern Pacific Ocean: Role of East Asian continental outflow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Z.; Guo, Z.</p> <p>2017-12-01</p> <p>We measured 15 parent polycyclic aromatic hydrocarbons (PAHs) in atmosphere and water during a research cruise from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) in the spring of 2015 to investigate the occurrence, <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange, and <span class="hlt">gas</span>-particle partitioning of PAHs with a particular focus on the influence of East Asian continental outflow. The gaseous PAH composition and identification of sources were consistent with PAHs from the upwind area, indicating that the gaseous PAHs (three- to five-ring PAHs) were influenced by upwind land pollution. In addition, <span class="hlt">air</span>-sea exchange fluxes of gaseous PAHs were estimated to be -54.2 to 107.4 ng m-2 d-1, and was indicative of variations of land-based PAH inputs. The logarithmic <span class="hlt">gas</span>-particle partition coefficient (logKp) of PAHs regressed linearly against the logarithmic subcooled liquid vapor pressure, with a slope of -0.25. This was significantly larger than the theoretical value (-1), implying disequilibrium between the gaseous and particulate PAHs over the NWP. The non-equilibrium of PAH <span class="hlt">gas</span>-particle partitioning was shielded from the volatilization of three-ring gaseous PAHs from seawater and lower soot <span class="hlt">concentrations</span> in particular when the oceanic <span class="hlt">air</span> masses prevailed. Modeling PAH absorption into organic matter and adsorption onto soot carbon revealed that the status of PAH <span class="hlt">gas</span>-particle partitioning deviated more from the modeling Kp for oceanic <span class="hlt">air</span> masses than those for continental <span class="hlt">air</span> masses, which coincided with higher volatilization of three-ring PAHs and confirmed the influence of <span class="hlt">air</span>-sea exchange. Meanwhile, significant linear regressions between logKp and logKoa (logKsa) for PAHs were observed for continental <span class="hlt">air</span> masses, suggesting the dominant effect of East Asian continental outflow on atmospheric PAHs over the NWP during the sampling campaign.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/71612','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/71612"><span>Volcanic <span class="hlt">gas</span> emissions and their impact on ambient <span class="hlt">air</span> character at Kilauea Volcano, Hawaii</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Sutton, A.J.; Elias, T.; Navarrete, R.</p> <p>1994-12-31</p> <p><span class="hlt">Gas</span> emissions from Kilauea occur from the summit caldera, along the middle East Rift Zone (ERZ), and where lava enters the ocean. We estimate that the current ERZ eruption of Kilauea releases between 400 metric tonnes of SO{sub 2} per day, during eruptive pauses, to as much as 1850 metric tonnes per day during actively erupting periods, along with lesser amounts of other chemically and radiatively active species including H{sub 2}S, HCl and HF. In order to characterize <span class="hlt">gas</span> emissions from Kilauea in a meaningful way for assessing environmental impact, we made a series of replicate grab-sample measurements of ambientmore » <span class="hlt">air</span> and precipitation at the summit of Kilauea, along its ERZ, and at coastal sites where lava enters the ocean. The grab-sampling data combined with SO{sub 2} emission rates, and continuous <span class="hlt">air</span> quality and meteorological monitoring at the summit of Kilauea show that the effects of these emissions on ambient <span class="hlt">air</span> character are a complex function of chemical reactivity, source geometry and effusivity, and local meteorology. Prevailing tradewinds typically carry the gases and aerosols released to the southwest, where they are further distributed by the regional wind regime. Episodes of kona, or low speed variable winds sometimes disrupt this pattern, however, and allow the gases and their oxidation products to collect at the summit and eastern side of the island. Summit solfatara areas of Kilauea are distinguished by moderate to high ambient SO{sub 2}, high H{sub 2}S at one location, and low H{sub 2}S at all others, and negligible HCl <span class="hlt">concentrations</span>, as measured 1 m from degassing point-sources. Summit solfatara rain water has high sulfate and low chloride ion <span class="hlt">concentrations</span>, and low pH.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29341855','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29341855"><span>Probabilistic assessment of the potential indoor <span class="hlt">air</span> impacts of vent-free <span class="hlt">gas</span> heating appliances in energy-efficient homes in the United States.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Whitmyre, Gary K; Pandian, Muhilan D</p> <p>2018-06-01</p> <p>Use of vent-free <span class="hlt">gas</span> heating appliances for supplemental heating in U.S. homes is increasing. However, there is currently a lack of information on the potential impact of these appliances on indoor <span class="hlt">air</span> quality for homes constructed according to energy-efficient and green building standards. A probabilistic analysis was conducted to estimate the impact of vent-free <span class="hlt">gas</span> heating appliances on indoor <span class="hlt">air</span> <span class="hlt">concentrations</span> of carbon monoxide (CO), nitrogen dioxide (NO 2 ), carbon dioxide (CO 2 ), water vapor, and oxygen in "tight" energy-efficient homes in the United States. A total of 20,000 simulations were conducted for each Department of Energy (DOE) heating region to capture a wide range of home sizes, appliance features, and conditions, by varying a number of parameters, e.g., room volume, house volume, outdoor humidity, <span class="hlt">air</span> exchange rates, appliance input rates (Btu/hr), and house heat loss factors. Predicted airborne levels of CO were below the U.S. Environmental Protection Agency (EPA) standard of 9 ppm for all modeled cases. The airborne <span class="hlt">concentrations</span> of NO 2 were below the U.S. Consumer Product Safety Commission (CPSC) guideline of 0.3 ppm and the Health Canada benchmark of 0.25 ppm in all cases and were below the World Health Organization (WHO) standard of 0.11 ppm in 99-100% of all cases. Predicted levels of CO 2 were below the Health Canada standard of 3500 ppm for all simulated cases. Oxygen levels in the room of vent-free heating appliance use were not significantly reduced. The great majority of cases in all DOE regions were associated with relative humidity (RH) levels from all indoor water vapor sources that were less than the EPA-recommended 70% RH maximum to avoid active mold and mildew growth. The conclusion of this investigation is that when installed in accordance with the manufacturer's instructions, vent-free <span class="hlt">gas</span> heating appliances maintain acceptable indoor <span class="hlt">air</span> quality in tight energy-efficient homes, as defined by the standards referenced in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010APS..DFD.MX008H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010APS..DFD.MX008H"><span>Coaxial twin-fluid atomization with pattern <span class="hlt">air</span> <span class="hlt">gas</span> streams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hei Ng, Chin; Aliseda, Alberto</p> <p>2010-11-01</p> <p>Coaxial twin-fluid atomization has numerous industrial applications, most notably fuel injection and spray coating. In the coating process of pharmaceutical tablets, the coaxial atomizing <span class="hlt">air</span> stream is accompanied by two diametrically opposed side jets that impinge on the liquid/<span class="hlt">gas</span> coaxial jets at an angle to produce an elliptical shape of the spray's cross section. Our study focuses on the influence of these side jets on the break up process and on the droplet velocity and diameter distribution along the cross section. The ultimate goal is to predict the size distribution and volume flux per unit area in the spray. With this predictive model, an optimal atomizing <span class="hlt">air</span>/pattern <span class="hlt">air</span> ratio can be found to achieve the desired coating result. This model is also crucial in scaling up the laboratory setup to production level. We have performed experiments with different atomized liquids, such as water and glycerine-water mixtures, that allow us to establish the effect of liquid viscosity, through the Ohnesorge number, in the spray characteristics. The <span class="hlt">gas</span> Reynolds number of our experiments ranges from 9000 to 18000 and the Weber number ranges from 400 to 1600. We will present the effect of pattern <span class="hlt">air</span> in terms of the resulting droplets size, droplet number density and velocity at various distances downstream of the nozzle where the effect of pattern <span class="hlt">air</span> is significant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24762065','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24762065"><span>Modeled occupational exposures to <span class="hlt">gas</span>-phase medical laser-generated <span class="hlt">air</span> contaminants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lippert, Julia F; Lacey, Steven E; Jones, Rachael M</p> <p>2014-01-01</p> <p>Exposure monitoring data indicate the potential for substantive exposure to laser-generated <span class="hlt">air</span> contaminants (LGAC); however the diversity of medical lasers and their applications limit generalization from direct workplace monitoring. Emission rates of seven previously reported <span class="hlt">gas</span>-phase constituents of medical laser-generated <span class="hlt">air</span> contaminants (LGAC) were determined experimentally and used in a semi-empirical two-zone model to estimate a range of plausible occupational exposures to health care staff. Single-source emission rates were generated in an emission chamber as a one-compartment mass balance model at steady-state. Clinical facility parameters such as room size and ventilation rate were based on standard ventilation and environmental conditions required for a laser surgical facility in compliance with regulatory agencies. All input variables in the model including point source emission rates were varied over an appropriate distribution in a Monte Carlo simulation to generate a range of time-weighted average (TWA) <span class="hlt">concentrations</span> in the near and far field zones of the room in a conservative approach inclusive of all contributing factors to inform future predictive models. The <span class="hlt">concentrations</span> were assessed for risk and the highest values were shown to be at least three orders of magnitude lower than the relevant occupational exposure limits (OELs). Estimated values do not appear to present a significant exposure hazard within the conditions of our emission rate estimates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23387144','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23387144"><span>[The reconstruction of two-dimensional distributions of <span class="hlt">gas</span> <span class="hlt">concentration</span> in the flat flame based on tunable laser absorption spectroscopy].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jiang, Zhi-Shen; Wang, Fei; Xing, Da-Wei; Xu, Ting; Yan, Jian-Hua; Cen, Ke-Fa</p> <p>2012-11-01</p> <p>The experimental method by using the tunable diode laser absorption spectroscopy combined with the model and algo- rithm was studied to reconstruct the two-dimensional distribution of <span class="hlt">gas</span> <span class="hlt">concentration</span> The feasibility of the reconstruction program was verified by numerical simulation A diagnostic system consisting of 24 lasers was built for the measurement of H2O in the methane/<span class="hlt">air</span> premixed flame. The two-dimensional distribution of H2O <span class="hlt">concentration</span> in the flame was reconstructed, showing that the reconstruction results reflect the real two-dimensional distribution of H2O <span class="hlt">concentration</span> in the flame. This diagnostic scheme provides a promising solution for combustion control.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A41J..05M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A41J..05M"><span>The value and limitations of global <span class="hlt">air</span>-sampling networks for improving our understanding trace <span class="hlt">gas</span> behavior</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Montzka, S. A.</p> <p>2016-12-01</p> <p>Measurements from global surface-based <span class="hlt">air</span> sampling networks provide a fundamental understanding of how and why <span class="hlt">concentrations</span> of long-lived trace gases are changing over time. Results from these networks are used to quantify trace-<span class="hlt">gas</span> <span class="hlt">concentrations</span> and their time-dependent changes on global and smaller scales, and thus provide a means to quantify emission rates, loss frequencies, and mixing processes. Substantial advances in measurement and sampling technologies and the ability of these programs to create and maintain reliable <span class="hlt">gas</span> standards mean that spatial <span class="hlt">concentration</span> gradients and time-dependent changes are often very reliably measured. The presence of multiple independent networks allows an assessment of this reliability. Furthermore, recent global `snap-shot' surveys (e.g., HIPPO and ATom) and ongoing atmospheric profiling programs help us assess the ability of surface-based data to describe <span class="hlt">concentration</span> distributions throughout most of the atmosphere ( 80% of its mass). In this overview talk, I'll explore the usefulness and limitations of existing long-term, ongoing sampling network programs and their advantages and disadvantages for characterizing <span class="hlt">concentrations</span> on global and regional scales, and how recent advances (and short-term sampling programs) help us assess the accuracy of the surface networks to provide estimates of source and sink magnitudes, and inter-annual variability in both.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PSST...23f5033M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PSST...23f5033M"><span>Post-discharge <span class="hlt">gas</span> composition of a large-gap DBD in humid <span class="hlt">air</span> by UV-Vis absorption spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moiseev, T.; Misra, N. N.; Patil, S.; Cullen, P. J.; Bourke, P.; Keener, K. M.; Mosnier, J. P.</p> <p>2014-12-01</p> <p>Large gap dielectric barrier discharges (DBD) provide non-thermal, non-equilibrium plasmas that can generate specific <span class="hlt">gas</span> chemistry with enhanced bactericidal effects when working in humid <span class="hlt">air</span>. The present study investigates the post-discharge <span class="hlt">gas</span> composition of such plasmas operated in humid <span class="hlt">air</span> using UV-Vis (200-800 nm) absorption spectroscopy. Absorbance spectra have been de-convoluted using direct deconvolution and iterative methods and results are correlated to the DBD electrical parameters. The high-voltage (56 and 70 kV rms) DBD plasma generated at 50 Hz frequency in a closed container over a 20 mm gap in <span class="hlt">air</span> with relative humidity (RH) of 5-70% has been characterized by I-V and capacitive methods. The post-discharge <span class="hlt">gas</span> composition at each RH is assessed by UV-Vis absorption spectroscopy for plasma exposure times of 15-120 s. The <span class="hlt">concentration</span> of ozone and nitrogen oxides (O3, NO2, NO3, N2O4) increases with plasma exposure time but a strong decrease in [O3] levels is obtained with increase in RH. The decrease in [O3] and an abundance of nitrogen oxides is ascribed to high specific power densities in the closed container and to increasing RH levels. The absorbance residual following deconvolution shows a strong band at 230-270 nm consistent with the presence of pernitric acid (HNO4) and other HNOx (x = 1, 3) species. Humid <span class="hlt">air</span> large gap DBD plasmas in closed containers generate along with O3, high levels of nitrogen oxides and HNOx (x = 1, 4) acids leading to increased bactericidal rates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=63911&keyword=us+AND+history&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=63911&keyword=us+AND+history&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>IMPACT OF AN OZONE GENERATOR <span class="hlt">AIR</span> CLEANER ON STYRENE <span class="hlt">CONCENTRATIONS</span> IN AN INDOOR <span class="hlt">AIR</span> QUALITY RESEARCH CHAMBER</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The paper gives results of an investigation of the impact of an ozone generator <span class="hlt">air</span> cleaner on vapor-phase styrene <span class="hlt">concentrations</span> in a full-scale indoor <span class="hlt">air</span> quality test chamber. The time history of the <span class="hlt">concentrations</span> of styrene and ozone is well predicted by a simulation model u...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol3/pdf/CFR-2010-title40-vol3-sec52-277.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol3/pdf/CFR-2010-title40-vol3-sec52-277.pdf"><span>40 CFR 52.277 - Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations. (a) The following rules are being retained...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol3/pdf/CFR-2014-title40-vol3-sec52-277.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol3/pdf/CFR-2014-title40-vol3-sec52-277.pdf"><span>40 CFR 52.277 - Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 40 Protection of Environment 3 2014-07-01 2014-07-01 false Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations. (a) The following rules are being retained...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol3/pdf/CFR-2011-title40-vol3-sec52-277.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol3/pdf/CFR-2011-title40-vol3-sec52-277.pdf"><span>40 CFR 52.277 - Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 40 Protection of Environment 3 2011-07-01 2011-07-01 false Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations. (a) The following rules are being retained...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol3/pdf/CFR-2012-title40-vol3-sec52-277.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol3/pdf/CFR-2012-title40-vol3-sec52-277.pdf"><span>40 CFR 52.277 - Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 40 Protection of Environment 3 2012-07-01 2012-07-01 false Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations. (a) The following rules are being retained...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol3/pdf/CFR-2013-title40-vol3-sec52-277.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol3/pdf/CFR-2013-title40-vol3-sec52-277.pdf"><span>40 CFR 52.277 - Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 40 Protection of Environment 3 2013-07-01 2013-07-01 false Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion <span class="hlt">gas</span> <span class="hlt">concentration</span> limitations. (a) The following rules are being retained...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70140168','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70140168"><span>Mercury <span class="hlt">concentrations</span> and distribution in soil, water, mine waste leachates, and <span class="hlt">air</span> in and around mercury mines in the Big Bend region, Texas, USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Gray, John E.; Theodorakos, Peter M.; Fey, David L.; Krabbenhoft, David P.</p> <p>2015-01-01</p> <p>Samples of soil, water, mine waste leachates, soil <span class="hlt">gas</span>, and <span class="hlt">air</span> were collected from areas mined for mercury (Hg) and baseline sites in the Big Bend area, Texas, to evaluate potential Hg contamination in the region. Soil samples collected within 300 m of an inactive Hg mine contained elevated Hg <span class="hlt">concentrations</span> (3.8–11 µg/g), which were considerably higher than Hg in soil collected from baseline sites (0.03–0.05 µg/g) distal (as much as 24 km) from mines. Only three soil samples collected within 300 m of the mine exceeded the probable effect <span class="hlt">concentration</span> for Hg of 1.06 µg/g, above which harmful effects are likely to be observed in sediment-dwelling organisms. <span class="hlt">Concentrations</span> of Hg in mine water runoff (7.9–14 ng/L) were generally higher than those found in springs and wells (0.05–3.1 ng/L), baseline streams (1.1–9.7 ng/L), and sources of drinking water (0.63–9.1 ng/L) collected in the Big Bend region. <span class="hlt">Concentrations</span> of Hg in all water samples collected in this study were considerably below the 2,000 ng/L drinking water Hg guideline and the 770 ng/L guideline recommended by the U.S. Environmental Protection Agency (USEPA) to protect aquatic wildlife from chronic effects of Hg. <span class="hlt">Concentrations</span> of Hg in water leachates obtained from leaching of mine wastes varied widely from <0.001 to 760 µg of Hg in leachate/g of sample leached, but only one leachate exceeded the USEPA Hg industrial soil screening level of 31 µg/g. <span class="hlt">Concentrations</span> of Hg in soil <span class="hlt">gas</span> collected at mined sites (690–82,000 ng/m3) were highly elevated compared to soil <span class="hlt">gas</span> collected from baseline sites (1.2–77 ng/m3). However, <span class="hlt">air</span> collected from mined areas at a height of 2 m above the ground surface contained <span class="hlt">concentrations</span> of Hg (4.9–64 ng/m3) that were considerably lower than Hg in soil <span class="hlt">gas</span> from the mined areas. Although <span class="hlt">concentrations</span> of Hg emitted from mine-contaminated soils and mine wastes were elevated, persistent wind in southwest Texas disperses Hg in the <span class="hlt">air</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000119049&hterms=water+purification&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwater%2Bpurification','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000119049&hterms=water+purification&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwater%2Bpurification"><span>Regenerable <span class="hlt">Air</span> Purification System for <span class="hlt">Gas</span>-Phase Contaminant Control</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Constantinescu, Ileana C.; Finn, John E.; LeVan, M. Douglas; Lung, Bernadette (Technical Monitor)</p> <p>2000-01-01</p> <p>Tests of a pre-prototype regenerable <span class="hlt">air</span> purification system (RAPS) that uses water vapor to displace adsorbed contaminants from an adsorbent column have been performed at NASA Ames Research Center. A unit based on this design can be used for removing trace <span class="hlt">gas</span>-phase contaminants from spacecraft cabin <span class="hlt">air</span> or from polluted process streams including incinerator exhaust. During the normal operation mode, contaminants are removed from the <span class="hlt">air</span> on the column. Regeneration of the column is performed on-line. During regeneration, contaminants are displaced and destroyed inside the closed oxidation loop. In this presentation we discuss initial experimental results for the performance of RAPS in the removal and treatment of several important spacecraft contaminant species from <span class="hlt">air</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28438993','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28438993"><span><span class="hlt">Air</span> quality, health, and climate implications of China's synthetic natural <span class="hlt">gas</span> development.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qin, Yue; Wagner, Fabian; Scovronick, Noah; Peng, Wei; Yang, Junnan; Zhu, Tong; Smith, Kirk R; Mauzerall, Denise L</p> <p>2017-05-09</p> <p>Facing severe <span class="hlt">air</span> pollution and growing dependence on natural <span class="hlt">gas</span> imports, the Chinese government plans to increase coal-based synthetic natural <span class="hlt">gas</span> (SNG) production. Although displacement of coal with SNG benefits <span class="hlt">air</span> quality, it increases CO 2 emissions. Due to variations in <span class="hlt">air</span> pollutant and CO 2 emission factors and energy efficiencies across sectors, coal replacement with SNG results in varying degrees of <span class="hlt">air</span> quality benefits and climate penalties. We estimate <span class="hlt">air</span> quality, human health, and climate impacts of SNG substitution strategies in 2020. Using all production of SNG in the residential sector results in an annual decrease of ∼32,000 (20,000 to 41,000) outdoor-<span class="hlt">air</span>-pollution-associated premature deaths, with ranges determined by the low and high estimates of the health risks. If changes in indoor/household <span class="hlt">air</span> pollution were also included, the decrease would be far larger. SNG deployment in the residential sector results in nearly 10 and 60 times greater reduction in premature mortality than if it is deployed in the industrial or power sectors, respectively. Due to inefficiencies in current household coal use, utilization of SNG in the residential sector results in only 20 to 30% of the carbon penalty compared with using it in the industrial or power sectors. Even if carbon capture and storage is used in SNG production with today's technology, SNG emits 22 to 40% more CO 2 than the same amount of conventional <span class="hlt">gas</span>. Among the SNG deployment strategies we evaluate, allocating currently planned SNG to households provides the largest <span class="hlt">air</span> quality and health benefits with the smallest carbon penalties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PNAS..114.4887Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PNAS..114.4887Q"><span><span class="hlt">Air</span> quality, health, and climate implications of China's synthetic natural <span class="hlt">gas</span> development</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qin, Yue; Wagner, Fabian; Scovronick, Noah; Peng, Wei; Yang, Junnan; Zhu, Tong; Smith, Kirk R.; Mauzerall, Denise L.</p> <p>2017-05-01</p> <p>Facing severe <span class="hlt">air</span> pollution and growing dependence on natural <span class="hlt">gas</span> imports, the Chinese government plans to increase coal-based synthetic natural <span class="hlt">gas</span> (SNG) production. Although displacement of coal with SNG benefits <span class="hlt">air</span> quality, it increases CO2 emissions. Due to variations in <span class="hlt">air</span> pollutant and CO2 emission factors and energy efficiencies across sectors, coal replacement with SNG results in varying degrees of <span class="hlt">air</span> quality benefits and climate penalties. We estimate <span class="hlt">air</span> quality, human health, and climate impacts of SNG substitution strategies in 2020. Using all production of SNG in the residential sector results in an annual decrease of ˜32,000 (20,000 to 41,000) outdoor-<span class="hlt">air</span>-pollution-associated premature deaths, with ranges determined by the low and high estimates of the health risks. If changes in indoor/household <span class="hlt">air</span> pollution were also included, the decrease would be far larger. SNG deployment in the residential sector results in nearly 10 and 60 times greater reduction in premature mortality than if it is deployed in the industrial or power sectors, respectively. Due to inefficiencies in current household coal use, utilization of SNG in the residential sector results in only 20 to 30% of the carbon penalty compared with using it in the industrial or power sectors. Even if carbon capture and storage is used in SNG production with today’s technology, SNG emits 22 to 40% more CO2 than the same amount of conventional <span class="hlt">gas</span>. Among the SNG deployment strategies we evaluate, allocating currently planned SNG to households provides the largest <span class="hlt">air</span> quality and health benefits with the smallest carbon penalties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930091836','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930091836"><span>The Measurement of Fuel-<span class="hlt">Air</span> Ratio by Analysis for the Oxidized Exhaust <span class="hlt">Gas</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gerrish, Harold C.; Meem, J. Lawrence, Jr.</p> <p>1943-01-01</p> <p>An investigation was made to determine a method of measuring fuel-<span class="hlt">air</span> ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-<span class="hlt">air</span> ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of <span class="hlt">air</span> and of fuel supplied and also by analysis of the oxidized exhaust <span class="hlt">gas</span> and of the normal exhaust <span class="hlt">gas</span>. Five fuels were used: gasoline that complied with Army-Navy fuel Specification No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene. The method of determining the fuel-<span class="hlt">air</span> ratio described in this report involves the measurement of the carbon-dioxide content of the oxidized exhaust <span class="hlt">gas</span> and the use of graphs for the presented equation. This method is considered useful in aircraft, in the field, or in the laboratory for a range of fuel-<span class="hlt">air</span> ratios from 0.047 to 0.124.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930093110','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930093110"><span>The Measurement of Fuel-<span class="hlt">air</span> Ratio by Analysis of the Oxidized Exhaust <span class="hlt">Gas</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Memm, J. Lawrence, Jr.</p> <p>1943-01-01</p> <p>An investigation was made to determine a method of measuring fuel-<span class="hlt">air</span> ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-<span class="hlt">air</span> ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of <span class="hlt">air</span> and of fuel supplied and also by analysis of the oxidized exhaust <span class="hlt">gas</span> and of the normal exhaust <span class="hlt">gas</span>. Five fuels were used: gasoline that complied with Army-Navy Fuel Specification, No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene. The method of determining the fuel-<span class="hlt">air</span> ratio described in this report involves the measurement of the carbon-dioxide content of the oxidized exhaust <span class="hlt">gas</span> and the use of graphs or the presented equation. This method is considered useful in aircraft, in the field, or in the laboratory for a range of fuel-<span class="hlt">air</span> ratios from 0.047 to 0.124</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1134313','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1134313"><span><span class="hlt">Air</span>/fuel supply system for use in a <span class="hlt">gas</span> turbine engine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Fox, Timothy A; Schilp, Reinhard; Gambacorta, Domenico</p> <p>2014-06-17</p> <p>A fuel injector for use in a <span class="hlt">gas</span> turbine engine combustor assembly. The fuel injector includes a main body and a fuel supply structure. The main body has an inlet end and an outlet end and defines a longitudinal axis extending between the outlet and inlet ends. The main body comprises a plurality of <span class="hlt">air</span>/fuel passages extending therethrough, each <span class="hlt">air</span>/fuel passage including an inlet that receives <span class="hlt">air</span> from a source of <span class="hlt">air</span> and an outlet. The fuel supply structure communicates with and supplies fuel to the <span class="hlt">air</span>/fuel passages for providing an <span class="hlt">air</span>/fuel mixture within each <span class="hlt">air</span>/fuel passage. The <span class="hlt">air</span>/fuel mixtures exit the main body through respective <span class="hlt">air</span>/fuel passage outlets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28850833','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28850833"><span>Low <span class="hlt">concentrations</span> of persistent organic pollutants (POPs) in <span class="hlt">air</span> at Cape Verde.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nøst, Therese Haugdahl; Halse, Anne Karine; Schlabach, Martin; Bäcklund, Are; Eckhardt, Sabine; Breivik, Knut</p> <p>2018-01-15</p> <p>Ambient <span class="hlt">air</span> is a core medium for monitoring of persistent organic pollutants (POPs) under the Stockholm Convention and is used in studies of global transports of POPs and their atmospheric sources and source regions. Still, data based on active <span class="hlt">air</span> sampling remain scarce in many regions. The primary objectives of this study were to (i) monitor <span class="hlt">concentrations</span> of selected POPs in <span class="hlt">air</span> outside West Africa, and (ii) to evaluate potential atmospheric processes and source regions affecting measured <span class="hlt">concentrations</span>. For this purpose, an active high-volume <span class="hlt">air</span> sampler was installed on the Cape Verde Atmospheric Observatory at Cape Verde outside the coast of West Africa. Sampling commenced in May 2012 and 43 samples (24h sampling) were collected until June 2013. The samples were analyzed for selected polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB) and chlordanes. The <span class="hlt">concentrations</span> of these POPs at Cape Verde were generally low and comparable to remote sites in the Arctic for several compounds. Seasonal trends varied between compounds and <span class="hlt">concentrations</span> exhibited strong temperature dependence for chlordanes. Our results indicate net volatilization from the Atlantic Ocean north of Cape Verde as sources of these POPs. <span class="hlt">Air</span> mass back trajectories demonstrated that <span class="hlt">air</span> masses measured at Cape Verde were generally transported from the Atlantic Ocean or the North African continent. Overall, the low <span class="hlt">concentrations</span> in <span class="hlt">air</span> at Cape Verde were likely explained by absence of major emissions in areas from which the <span class="hlt">air</span> masses originated combined with depletion during long-range atmospheric transport due to enhanced degradation under tropical conditions (high temperatures and <span class="hlt">concentrations</span> of hydroxyl radicals). Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A23B0201S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A23B0201S"><span>Impacts of Marcellus Shale Natural <span class="hlt">Gas</span> Production on Regional <span class="hlt">Air</span> Quality</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Swarthout, R.; Russo, R. S.; Zhou, Y.; Mitchell, B.; Miller, B.; Lipsky, E. M.; Sive, B. C.</p> <p>2012-12-01</p> <p>Natural <span class="hlt">gas</span> is a clean burning alternative to other fossil fuels, producing lower carbon dioxide (CO2) emissions during combustion. <span class="hlt">Gas</span> deposits located within shale rock or tight sand formations are difficult to access using conventional drilling techniques. However, horizontal drilling coupled with hydraulic fracturing is now widely used to enhance natural <span class="hlt">gas</span> extraction. Potential environmental impacts of these practices are currently being assessed because of the rapid expansion of natural <span class="hlt">gas</span> production in the U.S. Natural <span class="hlt">gas</span> production has contributed to the deterioration of <span class="hlt">air</span> quality in several regions, such as in Wyoming and Utah, that were near or downwind of natural <span class="hlt">gas</span> basins. We conducted a field campaign in southwestern Pennsylvania on 16-18 June 2012 to investigate the impact of <span class="hlt">gas</span> production operations in the Marcellus Shale on regional <span class="hlt">air</span> quality. A total of 235 whole <span class="hlt">air</span> samples were collected in 2-liter electropolished stainless- steel canisters throughout southwestern Pennsylvania in a regular grid pattern that covered an area of approximately 8500 square km. Day and night samples were collected at each grid point and additional samples were collected near active wells, flaring wells, fluid retention reservoirs, transmission pipelines, and a processing plant to assess the influence of different stages of the <span class="hlt">gas</span> production operation on emissions. The samples were analyzed at Appalachian State University for methane (CH4), CO2, C2-C10 nonmethane hydrocarbons (NMHCs), C1-C2 halocarbons, C1-C5 alkyl nitrates and selected reduced sulfur compounds. In-situ measurements of ozone (O3), CH4, CO2, nitric oxide (NO), total reactive nitrogen (NOy), formaldehyde (HCHO), and a range of volatile organic compounds (VOCs) were carried out at an upwind site and a site near active <span class="hlt">gas</span> wells using a mobile lab. Emissions associated with <span class="hlt">gas</span> production were observed throughout the study region. Elevated mixing ratios of CH4 and CO2 were observed in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title46-vol5/pdf/CFR-2013-title46-vol5-sec154-1350.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title46-vol5/pdf/CFR-2013-title46-vol5-sec154-1350.pdf"><span>46 CFR 154.1350 - Flammable <span class="hlt">gas</span> detection system.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-10-01</p> <p>... flammable <span class="hlt">gas</span> <span class="hlt">concentration</span> over the <span class="hlt">concentration</span> or volume ranges under paragraph (t) or (u) of this... a cargo <span class="hlt">concentration</span> that is 30% or less of the lower flammable limit in <span class="hlt">air</span> of the cargo carried... the space where the <span class="hlt">gas</span> detection system's readout is located and must meet § 154.1365. (h) Remote...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPS...306..329D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPS...306..329D"><span>Nitrogen-doped carbonaceous catalysts for <span class="hlt">gas</span>-diffusion cathodes for alkaline aluminum-<span class="hlt">air</span> batteries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davydova, E. S.; Atamanyuk, I. N.; Ilyukhin, A. S.; Shkolnikov, E. I.; Zhuk, A. Z.</p> <p>2016-02-01</p> <p>Cobalt tetramethoxyphenyl porphyrin and polyacrylonitrile - based catalysts for oxygen reduction reaction were synthesized and characterized by means of SEM, TEM, XPS, BET, limited evaporation method, rotating disc and rotating ring-disc electrode methods. Half-cell and Al-<span class="hlt">air</span> cell tests were carried out to determine the characteristics of <span class="hlt">gas</span>-diffusion cathodes. Effect of active layer thickness and its composition on the characteristics of the <span class="hlt">gas</span>-diffusion cathodes was investigated. Power density of 300 mW cm-2 was achieved for alkaline Al-<span class="hlt">air</span> cell with an <span class="hlt">air</span>-breathing polyacrylonitrile-based cathode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/862879','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/862879"><span>Vapor <span class="hlt">concentration</span> monitor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Bayly, John G.; Booth, Ronald J.</p> <p>1977-01-01</p> <p>An apparatus for monitoring the <span class="hlt">concentration</span> of a vapor, such as heavy water, having at least one narrow bandwidth in its absorption spectrum, in a sample <span class="hlt">gas</span> such as <span class="hlt">air</span>. The <span class="hlt">air</span> is drawn into a chamber in which the vapor content is measured by means of its radiation absorption spectrum. High sensitivity is obtained by modulating the wavelength at a relatively high frequency without changing its optical path, while high stability against zero drift is obtained by the low frequency interchange of the sample <span class="hlt">gas</span> to be monitored and of a reference sample. The variable HDO background due to natural humidity is automatically corrected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11099204','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11099204"><span>Determination of the <span class="hlt">air</span> w-value in proton beams using ionization chambers with <span class="hlt">gas</span> flow capability.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moyers, M F; Vatnitsky, S M; Miller, D W; Slater, J M</p> <p>2000-10-01</p> <p>The purpose of this work was to determine the w-value of <span class="hlt">air</span> for protons using the paired <span class="hlt">gas</span> method. Several plastic- and magnesium-walled chambers were used with <span class="hlt">air</span>, synthetic <span class="hlt">air</span>, nitrogen, and argon flowing gases. Using argon as a reference <span class="hlt">gas</span>, the w-value of <span class="hlt">air</span> was measured and ranged from 32.7 to 34.5 J/C for protons with energies encountered in radiotherapy. Using nitrogen as a reference <span class="hlt">gas</span>, the w-value of <span class="hlt">air</span> ranged from 35.2 to 35.4 J/C over the same range of proton energies. The w-value was found, at a given energy, to be independent of the ion chamber used. The uncertainty in these measurements was estimated at 5.2% at the 2sigma level. This uncertainty was dominated by the 4.4% uncertainty in the w-value of the reference <span class="hlt">gas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPA....8a5104L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPA....8a5104L"><span>Formation and coalescence of nanobubbles under controlled <span class="hlt">gas</span> <span class="hlt">concentration</span> and species</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Chenliang; Zhang, A.-Man; Wang, Shiping; Cui, Pu</p> <p>2018-01-01</p> <p>Using molecular dynamics simulations, the effects of <span class="hlt">gas</span> <span class="hlt">concentration</span> and species on the coalescence and growth of nanobubbles were systematically investigated. With increasing <span class="hlt">gas</span> <span class="hlt">concentration</span>, not only surface nanobubbles but also bulk nanobubbles are formed. The bulk nanobubble in water is less explored so far. Here, its coalescence, stability, movement trajectory and velocity are discussed. A comparison of the motion and coalescence of the bulk nanobubble to the surface nanobubble, directly demonstrates that the three-phase contact line plays a crucial role for surface nanobubble stability. Compared with the bubble size, the distance between surface nanobubbles is a more important factor to decide the merging order among three nanobubbles. The study also shows that three factors including the oversaturated <span class="hlt">gas</span> <span class="hlt">concentration</span>, the distance between surface nanobubbles, and the stronger solid-<span class="hlt">gas</span> interactions influence the formation of the <span class="hlt">gas</span>-enrichment layer at the solid-liquid interface. The result has an important significance to enhancing the boundary slip due to the presence of nanobubbles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....17.6257L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....17.6257L"><span>Nitro-polycyclic aromatic hydrocarbons - <span class="hlt">gas</span>-particle partitioning, mass size distribution, and formation along transport in marine and continental background <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lammel, Gerhard; Mulder, Marie D.; Shahpoury, Pourya; Kukučka, Petr; Lišková, Hana; Přibylová, Petra; Prokeš, Roman; Wotawa, Gerhard</p> <p>2017-05-01</p> <p>Nitro-polycyclic aromatic hydrocarbons (NPAH) are ubiquitous in polluted <span class="hlt">air</span> but little is known about their abundance in background <span class="hlt">air</span>. NPAHs were studied at one marine and one continental background site, i.e. a coastal site in the southern Aegean Sea (summer 2012) and a site in the central Great Hungarian Plain (summer 2013), together with the parent compounds, PAHs. A Lagrangian particle dispersion model was used to track <span class="hlt">air</span> mass history. Based on Lagrangian particle statistics, the urban influence on samples was quantified for the first time as a fractional dose to which the collected volume of <span class="hlt">air</span> had been exposed. At the remote marine site, the 3-4-ring NPAH (sum of 11 targeted species) <span class="hlt">concentration</span> was 23.7 pg m-3 while the <span class="hlt">concentration</span> of 4-ring PAHs (6 species) was 426 pg m-3. The most abundant NPAHs were 2-nitrofluoranthene (2NFLT) and 3-nitrophenanthrene. Urban fractional doses in the range of < 0.002-5.4 % were calculated. At the continental site, the Σ11 3-4-ring NPAH and Σ6 4-ring PAH were 58 and 663 pg m-3, respectively, with 9-nitroanthracene and 2NFLT being the most <span class="hlt">concentrated</span> amongst the targeted NPAHs. The NPAH levels observed in the marine background <span class="hlt">air</span> are the lowest ever reported and remarkably lower, by more than 1 order of magnitude, than 1 decade before. Day-night variation of NPAHs at the continental site reflected shorter lifetime during the day, possibly because of photolysis of some NPAHs. The yields of formation of 2NFLT and 2-nitropyrene (2NPYR) in marine <span class="hlt">air</span> seem to be close to the yields for OH-initiated photochemistry observed in laboratory experiments under high NOx conditions. Good agreement is found for the prediction of NPAH <span class="hlt">gas</span>-particle partitioning using a multi-phase poly-parameter linear free-energy relationship. Sorption to soot is found to be less significant for <span class="hlt">gas</span>-particle partitioning of NPAHs than for PAHs. The NPAH levels determined in the south-eastern outflow of Europe confirm intercontinental transport</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29294558','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29294558"><span>[Rapid determination of volatile organic compounds in workplace <span class="hlt">air</span> by protable <span class="hlt">gas</span> chromatography-mass spectrometer].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhu, H B; Su, C J; Tang, H F; Ruan, Z; Liu, D H; Wang, H; Qian, Y L</p> <p>2017-10-20</p> <p>Objective: To establish a method for rapid determination of 47 volatile organic compounds in the <span class="hlt">air</span> of workplace using portable <span class="hlt">gas</span> chromatography - mass spectrometer(GC - MS). Methods: The mixed standard <span class="hlt">gas</span> with different <span class="hlt">concentration</span> levels was made by using the static <span class="hlt">gas</span> distribution method with the high purity nitrogen as dilution <span class="hlt">gas</span>. The samples were injected into the GC - MS by a hand - held probe. Retention time and characteristic ion were used for qualitative analysis,and the internal standard method was usd for quantitation. Results: The 47 poisonous substances were separated and determined well. The linear range of this method was 0.2 - 16.0 mg/m(3),and the relative standard deviation of 45 volatile ovganic compounds was 3.8% - 15.8%. The average recovery was 79.3% - 119.0%. Conclusion: The method is simple,accurate,sensitive,has good separation effect,short analysis period, can be used for qualitative and quantitative analysis of volatile organic compounds in the workplace, and also supports the rapid identification and detection of occupational hazards.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ArTh...35...83C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ArTh...35...83C"><span>Thermo-economic comparative analysis of <span class="hlt">gas</span> turbine GT10 integrated with <span class="hlt">air</span> and steam bottoming cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Czaja, Daniel; Chmielnak, Tadeusz; Lepszy, Sebastian</p> <p>2014-12-01</p> <p>A thermodynamic and economic analysis of a GT10 <span class="hlt">gas</span> turbine integrated with the <span class="hlt">air</span> bottoming cycle is presented. The results are compared to commercially available combined cycle power plants based on the same <span class="hlt">gas</span> turbine. The systems under analysis have a better chance of competing with steam bottoming cycle configurations in a small range of the power output capacity. The aim of the calculations is to determine the final cost of electricity generated by the <span class="hlt">gas</span> turbine <span class="hlt">air</span> bottoming cycle based on a 25 MW GT10 <span class="hlt">gas</span> turbine with the exhaust <span class="hlt">gas</span> mass flow rate of about 80 kg/s. The article shows the results of thermodynamic optimization of the selection of the technological structure of <span class="hlt">gas</span> turbine <span class="hlt">air</span> bottoming cycle and of a comparative economic analysis. Quantities are determined that have a decisive impact on the considered units profitability and competitiveness compared to the popular technology based on the steam bottoming cycle. The ultimate quantity that can be compared in the calculations is the cost of 1 MWh of electricity. It should be noted that the systems analyzed herein are power plants where electricity is the only generated product. The performed calculations do not take account of any other (potential) revenues from the sale of energy origin certificates. Keywords: <span class="hlt">Gas</span> turbine <span class="hlt">air</span> bottoming cycle, <span class="hlt">Air</span> bottoming cycle, <span class="hlt">Gas</span> turbine, GT10</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4239943','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4239943"><span>Chemical Discrimination in Turbulent <span class="hlt">Gas</span> Mixtures with MOX Sensors Validated by <span class="hlt">Gas</span> Chromatography-Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón</p> <p>2014-01-01</p> <p>Chemical detection systems based on chemo-resistive sensors usually include a <span class="hlt">gas</span> chamber to control the sample <span class="hlt">air</span> flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the <span class="hlt">gas</span> <span class="hlt">concentration</span> fluctuations observed in natural environments and destroys the spatio-temporal information contained in <span class="hlt">gas</span> plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent <span class="hlt">gas</span> sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive <span class="hlt">gas</span> sensors are exposed to dynamic <span class="hlt">gas</span> mixtures generated with several <span class="hlt">concentration</span> levels at the sources. Moreover, the ground truth of <span class="hlt">gas</span> <span class="hlt">concentrations</span> at the sensor location was estimated by means of <span class="hlt">gas</span> chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient <span class="hlt">gas</span> <span class="hlt">concentration</span> coverage is used. We show that in open sampling systems, training the classifiers only on high <span class="hlt">concentrations</span> of gases produces less effective classification and that it is important to calibrate the classification method with data at low <span class="hlt">gas</span> <span class="hlt">concentrations</span> to achieve optimal performance. PMID:25325339</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25325339','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25325339"><span>Chemical discrimination in turbulent <span class="hlt">gas</span> mixtures with MOX sensors validated by <span class="hlt">gas</span> chromatography-mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón</p> <p>2014-10-16</p> <p>Chemical detection systems based on chemo-resistive sensors usually include a <span class="hlt">gas</span> chamber to control the sample <span class="hlt">air</span> flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the <span class="hlt">gas</span> <span class="hlt">concentration</span> fluctuations observed in natural environments and destroys the spatio-temporal information contained in <span class="hlt">gas</span> plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent <span class="hlt">gas</span> sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive <span class="hlt">gas</span> sensors are exposed to dynamic <span class="hlt">gas</span> mixtures generated with several <span class="hlt">concentration</span> levels at the sources. Moreover, the ground truth of <span class="hlt">gas</span> <span class="hlt">concentrations</span> at the sensor location was estimated by means of <span class="hlt">gas</span> chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient <span class="hlt">gas</span> <span class="hlt">concentration</span> coverage is used. We show that in open sampling systems, training the classifiers only on high <span class="hlt">concentrations</span> of gases produces less effective classification and that it is important to calibrate the classification method with data at low <span class="hlt">gas</span> <span class="hlt">concentrations</span> to achieve optimal performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26284986','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26284986"><span>Updated methods for assessing the impacts of nearby <span class="hlt">gas</span> drilling and production on neighborhood <span class="hlt">air</span> quality and human health.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Olaguer, Eduardo P; Erickson, Matthew; Wijesinghe, Asanga; Neish, Brad; Williams, Jeff; Colvin, John</p> <p>2016-02-01</p> <p>An explosive growth in natural <span class="hlt">gas</span> production within the last decade has fueled concern over the public health impacts of <span class="hlt">air</span> pollutant emissions from oil and <span class="hlt">gas</span> sites in the Barnett and Eagle Ford shale regions of Texas. Commonly acknowledged sources of uncertainty are the lack of sustained monitoring of ambient <span class="hlt">concentrations</span> of pollutants associated with <span class="hlt">gas</span> mining, poor quantification of their emissions, and inability to correlate health symptoms with specific emission events. These uncertainties are best addressed not by conventional monitoring and modeling technology, but by increasingly available advanced techniques for real-time mobile monitoring, microscale modeling and source attribution, and real-time broadcasting of <span class="hlt">air</span> quality and human health data over the World Wide Web. The combination of contemporary scientific and social media approaches can be used to develop a strategy to detect and quantify emission events from oil and <span class="hlt">gas</span> facilities, alert nearby residents of these events, and collect associated human health data, all in real time or near-real time. The various technical elements of this strategy are demonstrated based on the results of past, current, and planned future monitoring studies in the Barnett and Eagle Ford shale regions. Resources should not be invested in expanding the conventional <span class="hlt">air</span> quality monitoring network in the vicinity of oil and <span class="hlt">gas</span> exploration and production sites. Rather, more contemporary monitoring and data analysis techniques should take the place of older methods to better protect the health of nearby residents and maintain the integrity of the surrounding environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20681430','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20681430"><span><span class="hlt">Gas</span> dispersion and immobile <span class="hlt">gas</span> volume in solid and porous particle biofilter materials at low <span class="hlt">air</span> flow velocities.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sharma, Prabhakar; Poulsen, Tjalfe G</p> <p>2010-07-01</p> <p><span class="hlt">Gas</span>-phase dispersion in granular biofilter materials with a wide range of particle sizes was investigated using atmospheric <span class="hlt">air</span> and nitrogen as tracer gases. Two types of materials were used: (1) light extended clay aggregates (LECA), consisting of highly porous particles, and (2) gravel, consisting of solid particles. LECA is a commercial material that is used for insulation, as a soil conditioner, and as a carrier material in biofilters for <span class="hlt">air</span> cleaning. These two materials were selected to have approximately the same particle shape. Column <span class="hlt">gas</span> transport experiments were conducted for both materials using different mean particle diameters, different particle size ranges, and different <span class="hlt">gas</span> flow velocities. Measured breakthrough curves were modeled using the advection-dispersion equation modified for mass transfer between mobile and immobile <span class="hlt">gas</span> phases. The results showed that <span class="hlt">gas</span> dispersivity increased with increasing mean particle diameter for LECA but was independent of mean particle diameter for gravel. <span class="hlt">Gas</span> dispersivity also increased with increasing particle size range for both media. Dispersivities in LECA were generally higher than for gravel. The mobile <span class="hlt">gas</span> content in both materials increased with increasing <span class="hlt">gas</span> flow velocity but it did not show any strong dependency on mean particle diameter or particle size range. The relative fraction of mobile <span class="hlt">gas</span> compared with total porosity was highest for gravel and lowest for LECA likely because of its high internal porosity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23999382','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23999382"><span>Preliminary measurement of <span class="hlt">gas</span> <span class="hlt">concentrations</span> of perfluropropane using an analytical weighing balance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Clarkson, Douglas McG; Manna, Avinish; Hero, Mark</p> <p>2014-02-01</p> <p>We describe the use of an analytical weighing balance of measurement accuracy 0.00001g for determination of <span class="hlt">concentrations</span> of perfluropropane (C3F8) <span class="hlt">gas</span> used in ophthalmic surgical vitrectomy procedures. A range of test eyes corresponding to an eye volume of 6.1ml were constructed using 27 gauge needle exit ducts and separately 20 gauge (straight) and 23 gauge (angled) entrance ports. This method allowed determination of <span class="hlt">concentration</span> levels in the sample preparation syringe and also levels in test eyes. It was determined that a key factor influencing <span class="hlt">gas</span> <span class="hlt">concentrations</span> accuracy related to the method of <span class="hlt">gas</span> fill and the value of dead space of the <span class="hlt">gas</span> preparation/delivery system and with a significant contribution arising from the use of the particle filter. The weighing balance technique was identified as an appropriate technique for estimation of <span class="hlt">gas</span> <span class="hlt">concentrations</span>. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1875c0021I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1875c0021I"><span>The effect of environmental parameters to dust <span class="hlt">concentration</span> in <span class="hlt">air</span>-conditioned space</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ismail, A. M. M.; Manssor, N. A. S.; Nalisa, A.; Yahaya, N.</p> <p>2017-08-01</p> <p>Malaysia has a wet and hot climate, therefore most of the spaces are <span class="hlt">air</span> conditioned. The environment might affect dust <span class="hlt">concentration</span> inside a space and affect the indoor <span class="hlt">air</span> quality (IAQ). The main objective of this study is to study the dust <span class="hlt">concentration</span> collected inside enclosed <span class="hlt">air</span>-conditioned space. The measurement was done physically at four selected offices and two classrooms using a number of equipment to measure the dust <span class="hlt">concentration</span> and environmental parameters which are temperature and relative <span class="hlt">air</span> humidity. It was found that the highest dust <span class="hlt">concentration</span> produced in office (temperature of 24.7°C, relative humidity of 66.5%) is 0.075 mg/m3, as compared to classroom, the highest dust <span class="hlt">concentration</span> produced is 0.060 mg/m3 office (temperature of 25.9°C, relative humidity of 64.0%). However, both measurements show that value still within the safety level set by DOSH Malaysia (2005-2010) and ASHRAE 62.2 2016. The office contained higher dust <span class="hlt">concentration</span> compared to classroom because of frequent movement transpires daily due to the functional of the offices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70164484','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70164484"><span><span class="hlt">Gas</span> exchange rates across the sediment-water and <span class="hlt">air</span>-water interfaces in south San Francisco Bay</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hartman, Blayne; Hammond, Douglas E.</p> <p>1984-01-01</p> <p>Radon 222 <span class="hlt">concentrations</span> in the water and sedimentary columns and radon exchange rates across the sediment-water and <span class="hlt">air</span>-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainty of the determinations, about 20%. The annual average of benthic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the <span class="hlt">gas</span> transfer coefficient for radon exchange across the <span class="hlt">air</span>-water interface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. <span class="hlt">Gas</span> exchange is linearly dependent upon wind speed over a wind speed range of 3.2–6.4 m/s, but shows no dependence upon current velocity. <span class="hlt">Gas</span> transfer coefficients predicted from an empirical relationship between <span class="hlt">gas</span> exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical <span class="hlt">gas</span> exchange models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12578005','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12578005"><span>Effects of <span class="hlt">air</span> current speed on <span class="hlt">gas</span> exchange in plant leaves and plant canopies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kitaya, Y; Tsuruyama, J; Shibuya, T; Yoshida, M; Kiyota, M</p> <p>2003-01-01</p> <p>To obtain basic data on adequate <span class="hlt">air</span> circulation to enhance plant growth in a closed plant culture system in a controlled ecological life support system (CELSS), an investigation was made of the effects of the <span class="hlt">air</span> current speed ranging from 0.01 to 1.0 m s-1 on photosynthesis and transpiration in sweetpotato leaves and photosynthesis in tomato seedlings canopies. The <span class="hlt">gas</span> exchange rates in leaves and canopies were determined by using a chamber method with an infrared <span class="hlt">gas</span> analyzer. The net photosynthetic rate and the transpiration rate increased significantly as the <span class="hlt">air</span> current speeds increased from 0.01 to 0.2 m s-1. The transpiration rate increased gradually at <span class="hlt">air</span> current speeds ranging from 0.2 to 1.0 m s-1 while the net photosynthetic rate was almost constant at <span class="hlt">air</span> current speeds ranging from 0.5 to 1.0 m s-1. The increase in the net photosynthetic and transpiration rates were strongly dependent on decreased boundary-layer resistances against <span class="hlt">gas</span> diffusion. The net photosynthetic rate of the plant canopy was doubled by an increased <span class="hlt">air</span> current speed from 0.1 to 1.0 m s-1 above the plant canopy. The results demonstrate the importance of <span class="hlt">air</span> movement around plants for enhancing the <span class="hlt">gas</span> exchange in the leaf, especially in plant canopies in the CELSS. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=gas+AND+natural&pg=7&id=EJ278558','ERIC'); return false;" href="https://eric.ed.gov/?q=gas+AND+natural&pg=7&id=EJ278558"><span>The Use of an <span class="hlt">Air</span>-Natural <span class="hlt">Gas</span> Flame in Atomic Absorption.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Melucci, Robert C.</p> <p>1983-01-01</p> <p>Points out that excellent results are obtained using an <span class="hlt">air</span>-natural <span class="hlt">gas</span> flame in atomic absorption experiments rather than using an <span class="hlt">air</span>-acetylene flame. Good results are obtained for alkali metals, copper, cadmium, and zinc but not for the alkaline earths since they form refractory oxides. (Author/JN)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996AtmEn..30..929D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996AtmEn..30..929D"><span>Novel approach for tomographic reconstruction of <span class="hlt">gas</span> <span class="hlt">concentration</span> distributions in <span class="hlt">air</span>: Use of smooth basis functions and simulated annealing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drescher, A. C.; Gadgil, A. J.; Price, P. N.; Nazaroff, W. W.</p> <p></p> <p>Optical remote sensing and iterative computed tomography (CT) can be applied to measure the spatial distribution of gaseous pollutant <span class="hlt">concentrations</span>. We conducted chamber experiments to test this combination of techniques using an open path Fourier transform infrared spectrometer (OP-FTIR) and a standard algebraic reconstruction technique (ART). Although ART converged to solutions that showed excellent agreement with the measured ray-integral <span class="hlt">concentrations</span>, the solutions were inconsistent with simultaneously gathered point-sample <span class="hlt">concentration</span> measurements. A new CT method was developed that combines (1) the superposition of bivariate Gaussians to represent the <span class="hlt">concentration</span> distribution and (2) a simulated annealing minimization routine to find the parameters of the Gaussian basis functions that result in the best fit to the ray-integral <span class="hlt">concentration</span> data. This method, named smooth basis function minimization (SBFM), generated reconstructions that agreed well, both qualitatively and quantitatively, with the <span class="hlt">concentration</span> profiles generated from point sampling. We present an analysis of two sets of experimental data that compares the performance of ART and SBFM. We conclude that SBFM is a superior CT reconstruction method for practical indoor and outdoor <span class="hlt">air</span> monitoring applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850001757','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850001757"><span>Combustion <span class="hlt">Gas</span> Properties I-ASTM Jet a Fuel and Dry <span class="hlt">Air</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, R. E.; Trout, A. M.; Wear, J. D.; Mcbride, B. J.</p> <p>1984-01-01</p> <p>A series of computations was made to produce the equilibrium temperature and <span class="hlt">gas</span> composition for ASTM jet A fuel and dry <span class="hlt">air</span>. The computed tables and figures provide combustion <span class="hlt">gas</span> property data for pressures from 0.5 to 50 atmospheres and equivalence ratios from 0 to 2.0.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24076504','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24076504"><span>Evaluation of impact of shale <span class="hlt">gas</span> operations in the Barnett Shale region on volatile organic compounds in <span class="hlt">air</span> and potential human health risks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bunch, A G; Perry, C S; Abraham, L; Wikoff, D S; Tachovsky, J A; Hixon, J G; Urban, J D; Harris, M A; Haws, L C</p> <p>2014-01-15</p> <p>Shale <span class="hlt">gas</span> exploration and production (E&P) has experienced substantial growth across the U.S. over the last decade. The Barnett Shale, in north-central Texas, contains one of the largest, most active onshore <span class="hlt">gas</span> fields in North America, stretching across 5000 square miles and having an estimated 15,870 producing wells as of 2011. Given that these operations may occur in relatively close proximity to populated/urban areas, concerns have been expressed about potential impacts on human health. In response to these concerns, the Texas Commission on Environmental Quality established an extensive <span class="hlt">air</span> monitoring network in the region. This network provides a unique data set for evaluating the potential impact of shale <span class="hlt">gas</span> E&P activities on human health. As such, the objective of this study was to evaluate community-wide exposures to volatile organic compounds (VOCs) in the Barnett Shale region. In this current study, more than 4.6 million data points (representing data from seven monitors at six locations, up to 105 VOCs/monitor, and periods of record dating back to 2000) were evaluated. Measured <span class="hlt">air</span> <span class="hlt">concentrations</span> were compared to federal and state health-based <span class="hlt">air</span> comparison values (HBACVs) to assess potential acute and chronic health effects. None of the measured VOC <span class="hlt">concentrations</span> exceeded applicable acute HBACVs. Only one chemical (1,2-dibromoethane) exceeded its applicable chronic HBACV, but it is not known to be associated with shale <span class="hlt">gas</span> production activities. Annual average <span class="hlt">concentrations</span> were also evaluated in deterministic and probabilistic risk assessments and all risks/hazards were below levels of concern. The analyses demonstrate that, for the extensive number of VOCs measured, shale <span class="hlt">gas</span> production activities have not resulted in community-wide exposures to those VOCs at levels that would pose a health concern. With the high density of active wells in this region, these findings may be useful for understanding potential health risks in other shale play</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ACP....16.1895A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ACP....16.1895A"><span>Contribution of ship emissions to the <span class="hlt">concentration</span> and deposition of <span class="hlt">air</span> pollutants in Europe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aksoyoglu, Sebnem; Baltensperger, Urs; Prévôt, André S. H.</p> <p>2016-02-01</p> <p>Emissions from the marine transport sector are one of the least-regulated anthropogenic emission sources and contribute significantly to <span class="hlt">air</span> pollution. Although strict limits were introduced recently for the maximum sulfur content in marine fuels in the SECAs (sulfur emission control areas) and in EU ports, sulfur emissions outside the SECAs and emissions of other components in all European maritime areas have continued to increase in the last two decades. We have used the <span class="hlt">air</span> quality model CAMx (Comprehensive <span class="hlt">Air</span> Quality Model with Extensions) with and without ship emissions for the year 2006 to determine the effects of international shipping on the annual as well as seasonal <span class="hlt">concentrations</span> of ozone, primary and secondary components of PM2.5, and the dry and wet deposition of nitrogen and sulfur compounds in Europe. The largest changes in pollutant <span class="hlt">concentrations</span> due to ship emissions were predicted for summer. <span class="hlt">Concentrations</span> of particulate sulfate increased due to ship emissions in the Mediterranean (up to 60 %), the English Channel and the North Sea (30-35 %), while increases in particulate nitrate levels were found especially in the north, around the Benelux area (20 %), where there were high NH3 land-based emissions. Our model results showed that not only are the atmospheric <span class="hlt">concentrations</span> of pollutants affected by ship emissions, but also depositions of nitrogen and sulfur compounds increase significantly along the shipping routes. NOx emissions from the ships, especially in the English Channel and the North Sea, cause a decrease in the dry deposition of reduced nitrogen at source regions by moving it from the <span class="hlt">gas</span> phase to the particle phase which then contributes to an increase in the wet deposition at coastal areas with higher precipitation. In the western Mediterranean region, on the other hand, model results show an increase in the deposition of oxidized nitrogen (mostly HNO3) due to the ship traffic. Dry deposition of SO2 seems to be significant along</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/bul/b2190/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/bul/b2190/"><span>Joint inversion of acoustic and resistivity data for the estimation of <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lee, Myung W.</p> <p>2002-01-01</p> <p>Downhole log measurements, such as acoustic or electrical resistivity logs, are frequently used to estimate in situ <span class="hlt">gas</span> hydrate <span class="hlt">concentrations</span> in the pore space of sedimentary rocks. Usually the <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span> is estimated separately based on each log measurement. However, measurements are related to each other through the <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span>, so the <span class="hlt">gas</span> hydrate <span class="hlt">concentrations</span> can be estimated by jointly inverting available logs. Because the magnitude of slowness of acoustic and resistivity values differs by more than an order of magnitude, a least-squares method, weighted by the inverse of the observed values, is attempted. Estimating the resistivity of connate water and <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span> simultaneously is problematic, because the resistivity of connate water is independent of acoustics. In order to overcome this problem, a coupling constant is introduced in the Jacobian matrix. In the use of different logs to estimate <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span>, a joint inversion of different measurements is preferred to the averaging of each inversion result.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPS...297..202X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPS...297..202X"><span>Template-directed fabrication of porous <span class="hlt">gas</span> diffusion layer for magnesium <span class="hlt">air</span> batteries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xue, Yejian; Miao, He; Sun, Shanshan; Wang, Qin; Li, Shihua; Liu, Zhaoping</p> <p>2015-11-01</p> <p>The uniform micropore distribution in the <span class="hlt">gas</span> diffusion layers (GDLs) of the <span class="hlt">air</span>-breathing cathode is very important for the metal <span class="hlt">air</span> batteries. In this work, the super-hydrophobic GDL with the interconnected regular pores is prepared by a facile silica template method, and then the electrochemical properties of the Mg <span class="hlt">air</span> batteries containing these GDLs are investigated. The results indicate that the interconnected and uniform pore structure, the available water-breakout pressure and the high <span class="hlt">gas</span> permeability coefficient of the GDL can be obtained by the application of 30% silica template. The maximum power density of the Mg <span class="hlt">air</span> battery containing the GDL with 30% regular pores reaches 88.9 mW cm-2 which is about 1.2 times that containing the pristine GDL. Furthermore, the GDL with 30% regular pores exhibits the improved the long term hydrophobic stability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2954570','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2954570"><span>Predictors of Indoor <span class="hlt">Air</span> <span class="hlt">Concentrations</span> in Smoking and Non-Smoking Residences</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Héroux, Marie-Eve; Clark, Nina; Van Ryswyk, Keith; Mallick, Ranjeeta; Gilbert, Nicolas L.; Harrison, Ian; Rispler, Kathleen; Wang, Daniel; Anastassopoulos, Angelos; Guay, Mireille; MacNeill, Morgan; Wheeler, Amanda J.</p> <p>2010-01-01</p> <p>Indoor <span class="hlt">concentrations</span> of <span class="hlt">air</span> pollutants (benzene, toluene, formaldehyde, acetaldehyde, acrolein, nitrogen dioxide, particulate matter, elemental carbon and ozone) were measured in residences in Regina, Saskatchewan, Canada. Data were collected in 106 homes in winter and 111 homes in summer of 2007, with 71 homes participating in both seasons. In addition, data for relative humidity, temperature, <span class="hlt">air</span> exchange rates, housing characteristics and occupants’ activities during sampling were collected. Multiple linear regression analysis was used to construct season-specific models for the <span class="hlt">air</span> pollutants. Where smoking was a major contributor to indoor <span class="hlt">concentrations</span>, separate models were constructed for all homes and for those homes with no cigarette smoke exposure. The housing characteristics and occupants’ activities investigated in this study explained between 11% and 53% of the variability in indoor <span class="hlt">air</span> pollutant <span class="hlt">concentrations</span>, with ventilation, age of home and attached garage being important predictors for many pollutants. PMID:20948949</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25971229','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25971229"><span>[Confrontation of knowledge on alcohol <span class="hlt">concentration</span> in blood and in exhaled <span class="hlt">air</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bauer, Miroslav; Bauerová, Jiřina; Šikuta, Ján; Šidlo, Jozef</p> <p>2015-01-01</p> <p>The authors of the paper give a brief historical overview of the development of experimental alcohology in the former Czechoslovakia. Enhanced attention is paid to tests of work quality control of toxicological laboratories. Information on results of control tests of blood samples using the method of <span class="hlt">gas</span> chromatography in Slovakia and within a world-wide study "Eurotox 1990" is presented. There are pointed out the pitfalls related to objective evaluation of the analysis results interpreting alcohol <span class="hlt">concentration</span> in biological materials and the associated need to eliminate a negative influence of the human factor. The authors recommend performing analyses of alcohol in biological materials only at accredited workplaces and in the case of samples storage to secure a mandatory inhibition of phosphorylation process. There are analysed the reasons of numerical differences of analyses while taking evidence of alcohol in blood and in exhaled <span class="hlt">air</span>. The authors confirm analysis accuracy using the method of <span class="hlt">gas</span> chromatography along with breath analysers of exhaled <span class="hlt">air</span>. They highlight the need for making the analysis results more objective also through confrontation with the results of clinical examination and with examined circumstances. The authors suggest a method of elimination of the human factor, the most frequently responsible for inaccuracy, to a tolerable level (safety factor) and the need of sample analysis by two methods independent of each other or the need of analysis of two biological materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhSen...5...67W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhSen...5...67W"><span>A coal mine multi-point fiber ethylene <span class="hlt">gas</span> <span class="hlt">concentration</span> sensor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wei, Yubin; Chang, Jun; Lian, Jie; Liu, Tongyu</p> <p>2015-03-01</p> <p>Spontaneous combustion of the coal mine goaf is one of the main disasters in the coal mine. The detection technology based on symbolic <span class="hlt">gas</span> is the main means to realize the spontaneous combustion prediction of the coal mine goaf, and ethylene <span class="hlt">gas</span> is an important symbol <span class="hlt">gas</span> of spontaneous combustion in the coal accelerated oxidation stage. In order to overcome the problem of current coal ethylene detection, the paper presents a mine optical fiber multi-point ethylene <span class="hlt">concentration</span> sensor based on the tunable diode laser absorption spectroscopy. Based on the experiments and analysis of the near-infrared spectrum of ethylene, the system employed the 1.62 μm (DFB) wavelength fiber coupled distributed feedback laser as the light source. By using the wavelength scanning technique and developing a stable fiber coupled Herriot type long path <span class="hlt">gas</span> absorption cell, a ppm-level high sensitivity detecting system for the <span class="hlt">concentration</span> of ethylene <span class="hlt">gas</span> was realized, which could meet the needs of coal mine fire prevention goaf prediction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.A33D1559J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.A33D1559J"><span><span class="hlt">Gas</span> and Particulate Aircraft Emissions Measurements: Impacts on local <span class="hlt">air</span> quality.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jayne, J. T.; Onasch, T.; Northway, M.; Canagaratna, M.; Worsnop, D.; Timko, M.; Wood, E.; Miake-Lye, R.; Herndon, S.; Knighton, B.; Whitefield, P.; Hagen, D.; Lobo, P.; Anderson, B.</p> <p>2007-12-01</p> <p><span class="hlt">Air</span> travel and freight shipping by <span class="hlt">air</span> are becoming increasingly important and are expected to continue to expand. The resulting increases in the local <span class="hlt">concentrations</span> of pollutants, including particulate matter (PM), volatile organic compounds (VOCs), and nitrogen oxides (NOX), can have negative impacts on regional <span class="hlt">air</span> quality, human health and can impact climate change. In order to construct valid emission inventories, accurate measurements of aircraft emissions are needed. These measurements must be done both at the engine exit plane (certification) and downwind following the rapid cooling, dilution and initial atmospheric processing of the exhaust plume. We present here results from multiple field experiments which include the Experiment to Characterize Volatile Aerosol and Trace Species Emissions (EXCAVATE) and the four Aircraft Particle Emissions eXperiments (APEX- 1/Atlanta/2/3) which characterized <span class="hlt">gas</span> and particle emissions from both stationary or in-use aircraft. Emission indices (EIs) for NOx and VOCs and for particle number <span class="hlt">concentration</span>, refractory PM (black carbon soot) and volatile PM (primarily sulfate and organic) particles are reported. Measurements were made at the engine exit plane and at several downstream locations (10 and 30 meters) for a number of different engine types and engine thrust settings. A significant fraction of organic particle mass is composed of low volatility oil-related compounds and is not combustion related, potentially emitted by vents or heated surfaces within aircraft engines. Advected plumes measurements from in-use aircraft show that the practice of reduced thrust take-offs has a significant effect on total NOx and soot emitted in the vicinity of the airport. The measurements reported here represent a first observation of this effect and new insights have been gained with respect to the chemical processing of gases and particulates important to the urban airshed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28675854','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28675854"><span><span class="hlt">Air</span>-sea exchange and <span class="hlt">gas</span>-particle partitioning of polycyclic aromatic hydrocarbons over the northwestern Pacific Ocean: Role of East Asian continental outflow.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, Zilan; Lin, Tian; Li, Zhongxia; Jiang, Yuqing; Li, Yuanyuan; Yao, Xiaohong; Gao, Huiwang; Guo, Zhigang</p> <p>2017-11-01</p> <p>We measured 15 parent polycyclic aromatic hydrocarbons (PAHs) in atmosphere and water during a research cruise from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) in the spring of 2015 to investigate the occurrence, <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange, and <span class="hlt">gas</span>-particle partitioning of PAHs with a particular focus on the influence of East Asian continental outflow. The gaseous PAH composition and identification of sources were consistent with PAHs from the upwind area, indicating that the gaseous PAHs (three-to five-ring PAHs) were influenced by upwind land pollution. In addition, <span class="hlt">air</span>-sea exchange fluxes of gaseous PAHs were estimated to be -54.2-107.4 ng m -2 d -1 , and was indicative of variations of land-based PAH inputs. The logarithmic <span class="hlt">gas</span>-particle partition coefficient (logK p ) of PAHs regressed linearly against the logarithmic subcooled liquid vapor pressure (logP L 0 ), with a slope of -0.25. This was significantly larger than the theoretical value (-1), implying disequilibrium between the gaseous and particulate PAHs over the NWP. The non-equilibrium of PAH <span class="hlt">gas</span>-particle partitioning was shielded from the volatilization of three-ring gaseous PAHs from seawater and lower soot <span class="hlt">concentrations</span> in particular when the oceanic <span class="hlt">air</span> masses prevailed. Modeling PAH absorption into organic matter and adsorption onto soot carbon revealed that the status of PAH <span class="hlt">gas</span>-particle partitioning deviated more from the modeling K p for oceanic <span class="hlt">air</span> masses than those for continental <span class="hlt">air</span> masses, which coincided with higher volatilization of three-ring PAHs and confirmed the influence of <span class="hlt">air</span>-sea exchange. Meanwhile, significant linear regressions between logK p and logK oa (logK sa ) for PAHs were observed for continental <span class="hlt">air</span> masses, suggesting the dominant effect of East Asian continental outflow on atmospheric PAHs over the NWP during the sampling campaign. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA113484','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA113484"><span>Effect of Outside Combustion <span class="hlt">Air</span> on <span class="hlt">Gas</span> Furnace Efficiency.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1981-10-15</p> <p>Support Agency REPORT FESA-TS-2104 EFFECT OF OUTSIDE COMBUSTION <span class="hlt">AIR</span> ON <span class="hlt">GAS</span> FURNACE EFFICIENCY THOMAS E. BRISBANE Q KATHLEEN L. HANCOCK u JOHNS - MANVILLE SALES...and Dilution <span class="hlt">Air</span> With No Furnace Setback. 93 AO-A113 4~84 . JOHNS - MANVILLE SALES CORP DENVER CO RESEARCH AND OEV--ETC F/6 13/ 1 EFFECT OF OUTSIDE...NUMBER(S) Thomas E. Brisbane, Kathleen L. Hancock DAAK 70-78-D-0002 9. PERFORMING ORGANIZATION NAME AND ADDRESS 1O. PROGRAM ELEMENT. PR.;ECT, TASK Johns</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JASMS..26.1532O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JASMS..26.1532O"><span>In-Line Ozonation for Sensitive <span class="hlt">Air</span>-Monitoring of a Mustard-<span class="hlt">Gas</span> Simulant by Atmospheric Pressure Chemical Ionization Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Okumura, Akihiko</p> <p>2015-09-01</p> <p>A highly sensitive method for real-time <span class="hlt">air</span>-monitoring of mustard <span class="hlt">gas</span> (bis(2-chloroethyl) sulfide, HD), which is a lethal blister agent, is proposed. Humidified <span class="hlt">air</span> containing a HD simulant, 2-chloroethyl ethyl sulfide (2CEES), was mixed with ozone and then analyzed by using an atmospheric pressure chemical ionization ion trap tandem mass spectrometer. Mass-spectral ion peaks attributable to protonated molecules of intact, monooxygenated, and dioxygenated 2CEES (MH+, MOH+, and MO2H+, respectively) were observed. As ozone <span class="hlt">concentration</span> was increased from zero to 30 ppm, the signal intensity of MH+ sharply decreased, that of MOH+ increased once and then decreased, and that of MO2H+ sharply increased until reaching a plateau. The signal intensity of MO2H+ at the plateau was 40 times higher than that of MH+ and 100 times higher than that of MOH+ in the case without in-line ozonation. Twenty-ppm ozone <span class="hlt">gas</span> was adequate to give a linear calibration curve for 2CEES obtained by detecting the MO2H+ signal in the <span class="hlt">concentration</span> range up to 60 μg/m3, which is high enough for hygiene management. In the low <span class="hlt">concentration</span> range lower than 3 μg/m3, which is equal to the short-term exposure limit for HD, calibration plots unexpectedly fell off the linear calibration curve, but 0.6-μg/m3 vapor was actually detected with the signal-to-noise ratio of nine. Ozone was generated from instrumentation <span class="hlt">air</span> by using a simple and inexpensive home-made generator. 2CEES was ozonated in 1-m extended sampling tube in only 1 s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....4197C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....4197C"><span><span class="hlt">Gas</span> hydrate <span class="hlt">concentration</span> estimated from P- and S-wave velocities</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carcione, J. M.; Gei, D.</p> <p>2003-04-01</p> <p>We estimate the <span class="hlt">concentration</span> of <span class="hlt">gas</span> hydrate at the Mallik 2L-38 research site, Mackenzie Delta, Canada, using P- and S-wave velocities obtained from well logging and vertical seismic profiles (VSP). The theoretical velocities are obtained from a poro-viscoelastic model based on a Biot-type approach. It considers the existence of two solids (grains and <span class="hlt">gas</span> hydrate) and a fluid mixture and is based on the assumption that hydrate fills the pore space and shows interconnection. The moduli of the matrix formed by <span class="hlt">gas</span> hydrate are obtained from the percolation model described by Leclaire et al., (1994). An empirical mixing law introduced by Brie et al., (1995) provides the effective bulk modulus of the fluid phase, giving Wood's modulus at low frequency and Voigt's modulus at high frequencies. The dry-rock moduli are estimated from the VSP profile where the rock is assumed to be fully saturated with water, and the quality factors are obtained from the velocity dispersion observed between the sonic and VSP velocities. Attenuation is described by using a constant-Q model for the dry rock moduli. The amount of dissipation is estimated from the difference between the seismic velocities and the sonic-log velocities. We estimate the amount of <span class="hlt">gas</span> hydrate by fitting the sonic-log and seismic velocities to the theoretical velocities, using the <span class="hlt">concentration</span> of <span class="hlt">gas</span> hydrate as fitting parameter. We obtain hydrate <span class="hlt">concentrations</span> up to 75 %, average values of 43 and 47 % from the VSP P- and S-wave velocities, respectively, and 47 and 42 % from the sonic-log P- and S-wave velocities, respectively. These averages are computed from 897 to 1110 m, excluding the zones where there is no <span class="hlt">gas</span> hydrate. We found that modeling attenuation is important to obtain reliable results. largeReferences} begin{description} Brie, A., Pampuri, F., Marsala A.F., Meazza O., 1995, Shear Sonic Interpretation in <span class="hlt">Gas</span>-Bearing Sands, SPE Annual Technical Conference and Exhibition, Dallas, 1995. Carcione, J</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986BoLMe..35..125S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986BoLMe..35..125S"><span>Atmospheric dispersion of a heavier-than-<span class="hlt">air</span> <span class="hlt">gas</span> near a two-dimensional obstacle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sutton, S. B.; Brandt, H.; White, B. R.</p> <p>1986-04-01</p> <p>Flow over a two-dimensional obstacle and dispersion of a heavier-than-<span class="hlt">air</span> <span class="hlt">gas</span> near the obstacle were studied. Two species, one representing <span class="hlt">air</span> and the other representing the heavier-than-<span class="hlt">air</span> <span class="hlt">gas</span> were treated. Equations for mass and momentum were cast in mass-averaged form, with turbulent Reynolds stresses and mass fluxes modeled using eddy-viscosity and diffusivity hypotheses. A two-equation k-ɛ turbulence model was used to determine the effective turbulent viscosity. Streamline curvature and buoyancy corrections were added to the basic turbulence formulation. The model equations were solved using finite difference techniques. An alternating-direction-implicit (ADI) technique was used to solve the parabolic transport equations and a direct matrix solver was used to solve the elliptic pressure equation. Mesh sensitivities were investigated to determine the optimum mesh requirements for the final calculations. It was concluded that at least 10 grid spaces were required across the obstacle width and 15 across the obstacle height to obtain valid solutions. A non-uniform mesh was used to <span class="hlt">concentrate</span> the grid points at the top of the obstacle. Experimental measurements were made with <span class="hlt">air</span> flow over a 7.6 by 7.6 cm obstacle in a boundary-layer wind tunnel. Smoke visualization revealed a low-frequency oscillation of the bubble downstream of the obstacle. Hot-wire anemometer data are presented for the mean velocity and turbulent kinetic energy at the mid-plane of the obstacle and the mid-plane of the downstream recirculation bubble. A single hot-wire probe was found to be suitable for determining mean streamwise velocities with an accuracy of 11 %. The downstream recirculation bubble was unsteady and had a length range from 3 to 8 obstacle lengths. The experimental results for flow over the obstacle were compared with numerical calculations to validate the numerical solution procedure. A sensitivity study on the effect of curvature correction and variation of turbulence</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25760268','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25760268"><span>Relationship between acetaldehyde <span class="hlt">concentration</span> in mouth <span class="hlt">air</span> and tongue coating volume.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yokoi, Aya; Maruyama, Takayuki; Yamanaka, Reiko; Ekuni, Daisuke; Tomofuji, Takaaki; Kashiwazaki, Haruhiko; Yamazaki, Yutaka; Morita, Manabu</p> <p>2015-01-01</p> <p>Acetaldehyde is the first metabolite of ethanol and is produced in the epithelium by mucosal ALDH, while higher levels are derived from microbial oxidation of ethanol by oral microflora such as Candida species. However, it is uncertain whether acetaldehyde <span class="hlt">concentration</span> in human breath is related to oral condition or local production of acetaldehyde by oral microflora. The aim of this pilot study was to investigate the relationship between physiological acetaldehyde <span class="hlt">concentration</span> and oral condition in healthy volunteers. Sixty-five volunteers (51 males and 14 females, aged from 20 to 87 years old) participated in the present study. Acetaldehyde <span class="hlt">concentration</span> in mouth <span class="hlt">air</span> was measured using a portable monitor. Oral examination, detection of oral Candida species and assessment of alcohol sensitivity were performed. Acetaldehyde <span class="hlt">concentration</span> [median (25%, 75%)] in mouth <span class="hlt">air</span> was 170.7 (73.5, 306.3) ppb. Acetaldehyde <span class="hlt">concentration</span> in participants with a tongue coating status score of 3 was significantly higher than in those with a score of 1 (p<0.017). After removing tongue coating, acetaldehyde <span class="hlt">concentration</span> decreased significantly (p<0.05). Acetaldehyde <span class="hlt">concentration</span> was not correlated with other clinical parameters, presence of Candida species, smoking status or alcohol sensitivity. Physiological acetaldehyde <span class="hlt">concentration</span> in mouth <span class="hlt">air</span> was associated with tongue coating volume.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4349121','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4349121"><span>Relationship between acetaldehyde <span class="hlt">concentration</span> in mouth <span class="hlt">air</span> and tongue coating volume</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>YOKOI, Aya; MARUYAMA, Takayuki; YAMANAKA, Reiko; EKUNI, Daisuke; TOMOFUJI, Takaaki; KASHIWAZAKI, Haruhiko; YAMAZAKI, Yutaka; MORITA, Manabu</p> <p>2015-01-01</p> <p>Objective Acetaldehyde is the first metabolite of ethanol and is produced in the epithelium by mucosal ALDH, while higher levels are derived from microbial oxidation of ethanol by oral microflora such as Candida species. However, it is uncertain whether acetaldehyde <span class="hlt">concentration</span> in human breath is related to oral condition or local production of acetaldehyde by oral microflora. The aim of this pilot study was to investigate the relationship between physiological acetaldehyde <span class="hlt">concentration</span> and oral condition in healthy volunteers. Material and Methods Sixty-five volunteers (51 males and 14 females, aged from 20 to 87 years old) participated in the present study. Acetaldehyde <span class="hlt">concentration</span> in mouth <span class="hlt">air</span> was measured using a portable monitor. Oral examination, detection of oral Candida species and assessment of alcohol sensitivity were performed. Results Acetaldehyde <span class="hlt">concentration</span> [median (25%, 75%)] in mouth <span class="hlt">air</span> was 170.7 (73.5, 306.3) ppb. Acetaldehyde <span class="hlt">concentration</span> in participants with a tongue coating status score of 3 was significantly higher than in those with a score of 1 (p<0.017). After removing tongue coating, acetaldehyde <span class="hlt">concentration</span> decreased significantly (p<0.05). Acetaldehyde <span class="hlt">concentration</span> was not correlated with other clinical parameters, presence of Candida species, smoking status or alcohol sensitivity. Conclusion Physiological acetaldehyde <span class="hlt">concentration</span> in mouth <span class="hlt">air</span> was associated with tongue coating volume. PMID:25760268</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24712292','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24712292"><span>Atmospheric hydrocarbon emissions and <span class="hlt">concentrations</span> in the barnett shale natural <span class="hlt">gas</span> production region.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zavala-Araiza, Daniel; Sullivan, David W; Allen, David T</p> <p>2014-05-06</p> <p>Hourly ambient hydrocarbon <span class="hlt">concentration</span> data were collected, in the Barnett Shale Natural <span class="hlt">Gas</span> Production Region, using automated <span class="hlt">gas</span> chromatography (auto-GC), for the period from April 2010 to December 2011. Data for three sites were compared: a site in the geographical center of the natural <span class="hlt">gas</span> production region (Eagle Mountain Lake (EML)); a rural/suburban site at the periphery of the production region (Flower Mound Shiloh), and an urban site (Hinton). The dominant hydrocarbon species observed in the Barnett Shale region were light alkanes. Analyses of daily, monthly, and hourly patterns showed little variation in relative composition. Observed <span class="hlt">concentrations</span> were compared to <span class="hlt">concentrations</span> predicted using a dispersion model (AERMOD) and a spatially resolved inventory of volatile organic compounds (VOC) emissions from natural <span class="hlt">gas</span> production (Barnett Shale Special Emissions Inventory) prepared by the Texas Commission on Environmental Quality (TCEQ), and other emissions information. The predicted <span class="hlt">concentrations</span> of VOC due to natural <span class="hlt">gas</span> production were 0-40% lower than background corrected measurements, after accounting for potential under-estimation of certain emission categories. Hourly and daily variations in observed, background corrected <span class="hlt">concentrations</span> were primarily explained by variability in meteorology, suggesting that episodic emission events had little impact on hourly averaged <span class="hlt">concentrations</span>. Total emissions for VOC from natural <span class="hlt">gas</span> production sources are estimated to be approximately 25,300 tons/yr, when accounting for potential under-estimation of certain emission categories. This region produced, in 2011, approximately 5 bcf/d of natural <span class="hlt">gas</span> (100 Gg/d) for a VOC to natural <span class="hlt">gas</span> production ratio (mass basis) of 0.0006.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/circ/1969/0609/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/circ/1969/0609/report.pdf"><span>Mercury in soil <span class="hlt">gas</span> and <span class="hlt">air</span>--A potential tool in mineral exploration</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McCarthy, Joseph Howard; Vaughn, W.W.; Learned, R.E.; Meuschke, J.L.</p> <p>1969-01-01</p> <p>The mercury content in soil <span class="hlt">gas</span> and in the atmosphere was measured in several mining districts to test the possibility that the mercury content in the atmosphere is higher over ore deposits than over barren ground. At Cortez, Nev., the distribution of anorhalous amounts of mercury in the <span class="hlt">air</span> collected at ground level (soil <span class="hlt">gas</span>) correlates well with the distribution of gold-bearing rocks that are covered by as much as 100 feet of gravel. The mercury content in the atmosphere collected at an altitude of 200 feet by an aircraft was 20 times background over a mercury posit and 10 times background over two porphyry copper deposits. Measurement of mercury in soil <span class="hlt">gas</span> and <span class="hlt">air</span> may prove to be a valuable exploration tool.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11812433','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11812433"><span>Fixed dilated pupil (Urrets-Zavalia syndrome) after <span class="hlt">air/gas</span> injection after deep lamellar keratoplasty for keratoconus.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maurino, Vincenzo; Allan, Bruce D S; Stevens, Julian D; Tuft, Stephen J</p> <p>2002-02-01</p> <p>To describe three cases of fixed dilated pupil and presumed iris ischemia (Urrets-Zavalia syndrome) after anterior chamber <span class="hlt">air/gas</span> injection after deep lamellar keratoplasty for keratoconus. Interventional case series. Three eyes of three patients with keratoconus underwent deep lamellar keratoplasty and intraoperative or postoperative injection of <span class="hlt">air/gas</span> in the anterior chamber to appose the host-donor lamellar graft interface. Urrets-Zavalia syndrome was diagnosed on clinical grounds in three cases and was associated with the Descemet membrane microperforation intraoperatively and introduction of <span class="hlt">air/gas</span> into the anterior chamber intraoperatively or postoperatively. A fixed dilated pupil is an uncommon complication of penetrating keratoplasty for keratoconus that can also develop after deep lamellar keratoplasty. Leaving an <span class="hlt">air</span> or <span class="hlt">gas</span> bubble in the anterior chamber of a phakic eye after deep lamellar keratoplasty is a risk factor and should therefore be avoided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/862648','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/862648"><span>Process for hydrogen isotope <span class="hlt">concentration</span> between liquid water and hydrogen <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Stevens, William H.</p> <p>1976-09-21</p> <p>A process for hydrogen isotope exchange and <span class="hlt">concentration</span> between liquid water and hydrogen <span class="hlt">gas</span>, wherein liquid water and hydrogen <span class="hlt">gas</span> are contacted, in an exchange section, with one another and with at least one catalyst body comprising at least one metal selected from Group VIII of the Periodic Table and preferably a support therefor, the catalyst body has a liquid-water-repellent, <span class="hlt">gas</span> permeable polymer or organic resin coating, preferably a fluorinated olefin polymer or silicone coating, so that the isotope <span class="hlt">concentration</span> takes place by two simultaneously occurring steps, namely, ##EQU1## WHILE THE HYDROGEN <span class="hlt">GAS</span> FED TO THE EXCHANGE SECTION IS DERIVED IN A REACTOR VESSEL FROM LIQUID WATER THAT HAS PASSED THROUGH THE EXCHANGE SECTION.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H41B1335A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H41B1335A"><span>Multiobjective Policy Analysis to Evaluate <span class="hlt">Air</span> Quality Impacts of Oil and <span class="hlt">Gas</span> Regulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alongi, M.; Kasprzyk, J. R.; Milford, J.; Ryan, J. N.; Estep, M.</p> <p>2016-12-01</p> <p>Unconventional oil and <span class="hlt">gas</span> development (UOGD) using hydraulic fracturing and horizontal drilling has recently fostered an unprecedented acceleration in energy development. Regulations seek to protect the public health of communities in proximity to UOGD and the environmental quality of these regions, while maintaining economic benefits. One such regulation is the setback distance, which dictates the minimum distance between an oil and <span class="hlt">gas</span> well and an occupied structure, such as a residential or commercial building, or an area of special concern. This presentation discusses a new policy analysis framework for UOGD regulations, using the Borg multiobjective evolutionary algorithm (MOEA) coupled with AERMOD, a regulatory <span class="hlt">air</span> dispersion model. The initial results explore how setback distance and well density regulations could impact the number of wells that can be drilled, based on a set of performance objectives that model potential increases in benzene, a hazardous <span class="hlt">air</span> pollutant that has been linked to cancer and other detrimental health effects. The simulation calculates daily benzene averages using meteorological data from Greeley, CO. An important aspect of this work is to define representative quantitative objectives that accurately capture salient characteristics of the pollutant time series. For example, our framework will characterize the maximum <span class="hlt">concentration</span> found over the entire spatial domain and over the duration of the simulation. Frequency-based objectives will also be explored, such as the number of exceedances of the benchmark annual average benzene <span class="hlt">concentration</span> corresponding to a given level of cancer risk. The multiobjective analysis can also be expanded to integrate other objectives that represent performance-based outcomes on UOGD such as energy development profits, increases in noise pollution and decreases in property value. This research represents one application of how MOEAs can be used to inform policymaking for environmental regulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19943683','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19943683"><span>Determining <span class="hlt">air</span> quality and greenhouse <span class="hlt">gas</span> impacts of hydrogen infrastructure and fuel cell vehicles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stephens-Romero, Shane; Carreras-Sospedra, Marc; Brouwer, Jacob; Dabdub, Donald; Samuelsen, Scott</p> <p>2009-12-01</p> <p>Adoption of hydrogen infrastructure and hydrogen fuel cell vehicles (HFCVs) to replace gasoline internal combustion engine (ICE) vehicles has been proposed as a strategy to reduce criteria pollutant and greenhouse <span class="hlt">gas</span> (GHG) emissions from the transportation sector and transition to fuel independence. However, it is uncertain (1) to what degree the reduction in criteria pollutants will impact urban <span class="hlt">air</span> quality, and (2) how the reductions in pollutant emissions and concomitant urban <span class="hlt">air</span> quality impacts compare to ultralow emission gasoline-powered vehicles projected for a future year (e.g., 2060). To address these questions, the present study introduces a "spatially and temporally resolved energy and environment tool" (STREET) to characterize the pollutant and GHG emissions associated with a comprehensive hydrogen supply infrastructure and HFCVs at a high level of geographic and temporal resolution. To demonstrate the utility of STREET, two spatially and temporally resolved scenarios for hydrogen infrastructure are evaluated in a prototypical urban airshed (the South Coast <span class="hlt">Air</span> Basin of California) using geographic information systems (GIS) data. The well-to-wheels (WTW) GHG emissions are quantified and the <span class="hlt">air</span> quality is established using a detailed atmospheric chemistry and transport model followed by a comparison to a future gasoline scenario comprised of advanced ICE vehicles. One hydrogen scenario includes more renewable primary energy sources for hydrogen generation and the other includes more fossil fuel sources. The two scenarios encompass a variety of hydrogen generation, distribution, and fueling strategies. GHG emissions reductions range from 61 to 68% for both hydrogen scenarios in parallel with substantial improvements in urban <span class="hlt">air</span> quality (e.g., reductions of 10 ppb in peak 8-h-averaged ozone and 6 mug/m(3) in 24-h-averaged particulate matter <span class="hlt">concentrations</span>, particularly in regions of the airshed where <span class="hlt">concentrations</span> are highest for the gasoline scenario).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A44A..04D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A44A..04D"><span>Mobile Measurements of <span class="hlt">Gas</span> and Particle Emissions from Marcellus Shale <span class="hlt">Gas</span> Development</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>DeCarlo, P. F.; Goetz, J. D.; Floerchinger, C. R.; Fortner, E.; Wormhoudt, J.; Knighton, W. B.; Herndon, S.; Kolb, C. E.; Shaw, S. L.; Knipping, E. M.</p> <p>2013-12-01</p> <p>Production of natural <span class="hlt">gas</span> in the Marcellus shale is increasing rapidly due to the vast quantities of natural <span class="hlt">gas</span> stored in the formation. Transient and long-term activities have associated emissions to the atmosphere of methane, volatile organic compounds, NOx, particulates and other species from <span class="hlt">gas</span> production and transport infrastructure. In the summer of 2012, a team of researchers from Drexel University and Aerodyne Research deployed the Aerodyne mobile laboratory (AML) and measured in-situ <span class="hlt">concentrations</span> of <span class="hlt">gas</span>-phase and aerosol chemical components in the main <span class="hlt">gas</span> producing regions of Pennsylvania, with the overall goal of understanding the impacts to regional ozone and particulate matter (PM) <span class="hlt">concentrations</span>. State-of-the-art instruments including quantum cascade laser systems, proton transfer mass spectrometry, tunable diode lasers and a soot particle aerosol mass spectrometer, were used quantify <span class="hlt">concentrations</span> of pollutants of interest. Chemical species measured include methane, ethane, NO, NO2, CO, CO2, SO2, and many volatile organic compounds, and aerosol size and chemical composition. Tracer-release techniques were employed to link sources with emissions and to quantify emission rates from <span class="hlt">gas</span> facilities, in order to understand the regional burden of these chemical species from oil and <span class="hlt">gas</span> development in the Marcellus. Measurements were conducted in two regions of Pennsylvania: the NE region that is predominantly dry <span class="hlt">gas</span> (95% + methane), and the SW region where wet <span class="hlt">gas</span> (containing greater than 5% higher hydrocarbons) is found. Regional scale measurements of current levels of <span class="hlt">air</span> pollutants will be shown and will put into context how further development of the <span class="hlt">gas</span> resource in one of the largest natural <span class="hlt">gas</span> fields in the world impacts <span class="hlt">air</span> quality in a region upwind of the highly urbanized east coast corridor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29738920','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29738920"><span>Non-contact ultrasonic <span class="hlt">gas</span> flow metering using <span class="hlt">air</span>-coupled leaky Lamb waves.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fan, Zichuan; Jiang, Wentao; Wright, William M D</p> <p>2018-04-23</p> <p>This paper describes a completely non-contact ultrasonic method of <span class="hlt">gas</span> flow metering using <span class="hlt">air</span>-coupled leaky Lamb waves. To show proof of principle, a simplified representation of <span class="hlt">gas</span> flow in a duct, comprising two separated thin isotropic plates with a <span class="hlt">gas</span> flowing between them, has been modelled and investigated experimentally. An airborne compression wave emitted from an <span class="hlt">air</span>-coupled capacitive ultrasonic transducer excited a leaky Lamb wave in the first plate in a non-contact manner. The leakage of this Lamb wave crossed the <span class="hlt">gas</span> flow at an angle between the two plates as a compression wave, and excited a leaky Lamb wave in the second plate. An <span class="hlt">air</span>-coupled capacitive ultrasonic transducer on the opposite side of this second plate then detected the airborne compression wave leakage from the second Lamb wave. As the <span class="hlt">gas</span> flow shifted the wave field between the two plates, the point of Lamb wave excitation in the second plate was displaced in proportion to the <span class="hlt">gas</span> flow rate. Two such measurements, in opposite directions, formed a completely non-contact contra-propagating Lamb wave flow meter, allowing measurement of the flow velocity between the plates. A COMSOL Multiphysics® model was used to visualize the wave fields, and accurately predicted the time differences that were then measured experimentally. Experiments using different Lamb wave frequencies and plate materials were also similarly verified. This entirely non-contact airborne approach to Lamb wave flow metering could be applied in place of clamp-on techniques in thin-walled ducts or pipes. Copyright © 2018 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010OcSci...6..913J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010OcSci...6..913J"><span>A numerical scheme to calculate temperature and salinity dependent <span class="hlt">air</span>-water transfer velocities for any <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, M. T.</p> <p>2010-10-01</p> <p>The ocean-atmosphere flux of a <span class="hlt">gas</span> can be calculated from its measured or estimated <span class="hlt">concentration</span> gradient across the <span class="hlt">air</span>-sea interface and the transfer velocity (a term representing the conductivity of the layers either side of the interface with respect to the <span class="hlt">gas</span> of interest). Traditionally the transfer velocity has been estimated from empirical relationships with wind speed, and then scaled by the Schmidt number of the <span class="hlt">gas</span> being transferred. Complex, physically based models of transfer velocity (based on more physical forcings than wind speed alone), such as the NOAA COARE algorithm, have more recently been applied to well-studied gases such as carbon dioxide and DMS (although many studies still use the simpler approach for these gases), but there is a lack of validation of such schemes for other, more poorly studied gases. The aim of this paper is to provide a flexible numerical scheme which will allow the estimation of transfer velocity for any <span class="hlt">gas</span> as a function of wind speed, temperature and salinity, given data on the solubility and liquid molar volume of the particular <span class="hlt">gas</span>. New and existing parameterizations (including a novel empirical parameterization of the salinity-dependence of Henry's law solubility) are brought together into a scheme implemented as a modular, extensible program in the R computing environment which is available in the supplementary online material accompanying this paper; along with input files containing solubility and structural data for ~90 gases of general interest, enabling the calculation of their total transfer velocities and component parameters. Comparison of the scheme presented here with alternative schemes and methods for calculating <span class="hlt">air</span>-sea flux parameters shows good agreement in general. It is intended that the various components of this numerical scheme should be applied only in the absence of experimental data providing robust values for parameters for a particular <span class="hlt">gas</span> of interest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26726459','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26726459"><span>Preparation of Fiber Based Binder Materials to Enhance the <span class="hlt">Gas</span> Adsorption Efficiency of Carbon <span class="hlt">Air</span> Filter.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lim, Tae Hwan; Choi, Jeong Rak; Lim, Dae Young; Lee, So Hee; Yeo, Sang Young</p> <p>2015-10-01</p> <p>Fiber binder adapted carbon <span class="hlt">air</span> filter is prepared to increase <span class="hlt">gas</span> adsorption efficiency and environmental stability. The filter prevents harmful gases, as well as particle dusts in the <span class="hlt">air</span> from entering the body when a human inhales. The basic structure of carbon <span class="hlt">air</span> filter is composed of spunbond/meltblown/activated carbon/bottom substrate. Activated carbons and meltblown layer are adapted to increase <span class="hlt">gas</span> adsorption and dust filtration efficiency, respectively. Liquid type adhesive is used in the conventional carbon <span class="hlt">air</span> filter as a binder material between activated carbons and other layers. However, it is thought that the liquid binder is not an ideal material with respect to its bonding strength and liquid flow behavior that reduce <span class="hlt">gas</span> adsorption efficiency. To overcome these disadvantages, fiber type binder is introduced in our study. It is confirmed that fiber type binder adapted <span class="hlt">air</span> filter media show higher strip strength, and their <span class="hlt">gas</span> adsorption efficiencies are measured over 42% during 60 sec. These values are higher than those of conventional filter. Although the differential pressure of fiber binder adapted <span class="hlt">air</span> filter is relatively high compared to the conventional one, short fibers have a good potential as a binder materials of activated carbon based <span class="hlt">air</span> filter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title10-vol4/pdf/CFR-2010-title10-vol4-sec835-209.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title10-vol4/pdf/CFR-2010-title10-vol4-sec835-209.pdf"><span>10 CFR 835.209 - <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... Section 835.209 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External Exposure § 835.209 <span class="hlt">Concentrations</span> of radioactive material in <span class="hlt">air</span>. (a) The derived <span class="hlt">air</span>... exposures to airborne radioactive material. (b) The estimation of internal dose shall be based on bioassay...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4884879','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4884879"><span>Effect of soil moisture on seasonal variation in indoor radon <span class="hlt">concentration</span>: modelling and measurements in 326 Finnish houses</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Arvela, H.; Holmgren, O.; Hänninen, P.</p> <p>2016-01-01</p> <p>The effect of soil moisture on seasonal variation in soil <span class="hlt">air</span> and indoor radon is studied. A brief review of the theory of the effect of soil moisture on soil <span class="hlt">air</span> radon has been presented. The theoretical estimates, together with soil moisture measurements over a period of 10 y, indicate that variation in soil moisture evidently is an important factor affecting the seasonal variation in soil <span class="hlt">air</span> radon <span class="hlt">concentration</span>. Partitioning of radon <span class="hlt">gas</span> between the water and <span class="hlt">air</span> fractions of soil pores is the main factor increasing soil <span class="hlt">air</span> radon <span class="hlt">concentration</span>. On two example test sites, the relative standard deviation of the calculated monthly average soil <span class="hlt">air</span> radon <span class="hlt">concentration</span> was 17 and 26 %. Increased soil moisture in autumn and spring, after the snowmelt, increases soil <span class="hlt">gas</span> radon <span class="hlt">concentrations</span> by 10–20 %. In February and March, the soil <span class="hlt">gas</span> radon <span class="hlt">concentration</span> is in its minimum. Soil temperature is also an important factor. High soil temperature in summer increased the calculated soil <span class="hlt">gas</span> radon <span class="hlt">concentration</span> by 14 %, compared with winter values. The monthly indoor radon measurements over period of 1 y in 326 Finnish houses are presented and compared with the modelling results. The model takes into account radon entry, climate and <span class="hlt">air</span> exchange. The measured radon <span class="hlt">concentrations</span> in autumn and spring were higher than expected and it can be explained by the seasonal variation in the soil moisture. The variation in soil moisture is a potential factor affecting markedly to the high year-to-year variation in the annual or seasonal average radon <span class="hlt">concentrations</span>, observed in many radon studies. PMID:25899611</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS33A1995S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS33A1995S"><span>Tracking Dissolved Methane <span class="hlt">Concentrations</span> near Active Seeps and <span class="hlt">Gas</span> Hydrates: Sea of Japan.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Snyder, G. T.; Aoki, S.; Matsumoto, R.; Tomaru, H.; Owari, S.; Nakajima, R.; Doolittle, D. F.; Brant, B.</p> <p>2015-12-01</p> <p>A number of regions in the Sea of Japan are known for active <span class="hlt">gas</span> venting and for <span class="hlt">gas</span> hydrate exposures on the sea floor. In this investigation we employed several <span class="hlt">gas</span> sensors mounted on a ROV in order to determine the <span class="hlt">concentrations</span> of dissolved methane in the water near these sites. Methane <span class="hlt">concentrations</span> were determined during two-second intervals throughout each ROV deployment during the cruise. The methane sensor deployments were coupled with seawater sampling using Niskin bottles. Dissolved <span class="hlt">gas</span> <span class="hlt">concentrations</span> were later measured using <span class="hlt">gas</span> chromatography in order to compare with the sensor results taken at the same time. The observed maximum dissolved methane <span class="hlt">concentrations</span> were much lower than saturation values, even when the ROV manipulators were in contact with <span class="hlt">gas</span> hydrate. Nonetheless, dissolved <span class="hlt">concentrations</span> did reach several thousands of nmol/L near <span class="hlt">gas</span> hydrate exposures and <span class="hlt">gas</span> bubbles, more than two orders of magnitude over the instrumental detection limits. Most of the sensors tested were able to detect dissolved methane <span class="hlt">concentrations</span> as low as 10 nmol/L which permitted detection when the ROV approached methane plume sites, even from several tens of meters above the sea floor. Despite the low detection limits, the methane sensors showed variable response times when returning to low-background seawater (~5nM). For some of the sensors, the response time necessary to return to background values occurred in a matter of minutes, while for others it took several hours. Response time, as well as detection limit, should be an important consideration when selecting methane sensors for ROV or AUV investigations. This research was made possible, in part, through funding provided by the Japanese Ministry of Economy, Trade and Industry (METI).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A24F..04C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A24F..04C"><span>Evaluating Oil and <span class="hlt">Gas</span> Speciation Profiles with Factor Analysis of Ambient Volatile Organic Compound <span class="hlt">Concentrations</span> in the Colorado Front Range</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Capps, S.; Paranjothi, G.; Pierce, G. E.; Milford, J. B.</p> <p>2016-12-01</p> <p>Increased oil and <span class="hlt">gas</span> (O&G) development, particularly through the use of hydraulic fracturing, in the Denver-Julesburg Basin (DJB) in Colorado over the last decade has been identified as a source of emissions of <span class="hlt">air</span> pollutants, which are now included in chemical transport modeling. As one effort to evaluate its impact, ambient <span class="hlt">concentrations</span> of volatile organic compounds (VOCs) that serve as precursors to ozone formation were measured in an Ozone Precursor Study conducted by the Colorado Department of Public Health and Environment during 2013 and 2014. The study included 6 - 9 a.m. measurements of an extensive suite of ozone-precursor VOCs from a site in an area of intensive O&G development in Platteville, CO, and another site in downtown Denver, CO. To evaluate the influences of urban activity or O&G development on these ambient <span class="hlt">concentrations</span>, we used the U.S. EPA's Positive Matrix Factorization (PMF) tool. A five-factor PMF solution was selected as providing the best fit to the dataset comprised of VOC measurements for both years and both sites. One PMF factor matches the VOC emissions speciation profile for the flashing <span class="hlt">gas</span> composition for condensate tanks in the DJB that was developed by the Western Regional <span class="hlt">Air</span> Partnership for use in chemical transport modeling in the region. The contribution of this factor to individual and total VOC <span class="hlt">concentrations</span> and ozone production reactivity is evaluated for Platteville and Denver.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26448492','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26448492"><span>Treatment of reverse osmosis (RO) <span class="hlt">concentrate</span> by the combined Fe/Cu/<span class="hlt">air</span> and Fenton process (1stFe/Cu/<span class="hlt">air</span>-Fenton-2ndFe/Cu/<span class="hlt">air</span>).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ren, Yi; Yuan, Yue; Lai, Bo; Zhou, Yuexi; Wang, Juling</p> <p>2016-01-25</p> <p>To decompose or transform the toxic and refractory reverse osmosis (RO) <span class="hlt">concentrate</span> and improve the biodegradability, 1stFe/Cu/<span class="hlt">air</span>-Fenton-2ndFe/Cu/<span class="hlt">air</span> were developed to treat RO <span class="hlt">concentrate</span> obtained from an amino acid production plant in northern China. First, their operating conditions were optimized thoroughly. Furthermore, 5 control experiments were setup to confirm the superiority of 1stFe/Cu/<span class="hlt">air</span>-Fenton-2ndFe/Cu/<span class="hlt">air</span> and synergistic reaction between Fe/Cu/<span class="hlt">air</span> and Fenton. The results suggest that the developed method could obtain high COD removal (65.1%) and BOD5/COD ratio (0.26) due to the synergistic reaction between Fe/Cu/<span class="hlt">air</span> and Fenton. Under the optimal conditions, the influent and effluent of 1stFe/Cu/<span class="hlt">air</span>-Fenton-2ndFe/Cu/<span class="hlt">air</span> and 5 control experiments were analyzed by using UV, FTIR, EEM and LC, which confirm the superiority of 1stFe/Cu/<span class="hlt">air</span>-Fenton-2ndFe/Cu/<span class="hlt">air</span>. Therefore, the developed method in this study is a promising process for treatment of RO <span class="hlt">concentrate</span>. Copyright © 2015 Elsevier B.V. All rights reserved.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24643387','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24643387"><span><span class="hlt">Concentrations</span>, atmospheric partitioning, and <span class="hlt">air</span>-water/soil surface exchange of polychlorinated dibenzo-p-dioxin and dibenzofuran along the upper reaches of the Haihe River basin, North China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nie, Zhiqiang; Die, Qingqi; Yang, Yufei; Tang, Zhenwu; Wang, Qi; Huang, Qifei</p> <p>2014-01-01</p> <p>Polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/PCDF) were overall measured and compared in ambient <span class="hlt">air</span>, water, soils, and sediments along the upper reaches of the Haihe River of North China, so as to evaluate their <span class="hlt">concentrations</span>, profiles, and to understand the processes of <span class="hlt">gas</span>-particle partitioning and <span class="hlt">air</span>-water/soil exchange. The following results were obtained: (1) The average <span class="hlt">concentrations</span> (toxic equivalents, TEQs) of 2,3,7,8-PCDD/PCDF in <span class="hlt">air</span>, water, sediment, and soil samples were 4,855 fg/m(3), 9.5 pg/L, 99.2 pg/g dry weight (dw), and 56.4 pg/g (203 fg TEQ/m(3), 0.46 pg TEQ/L, 2.2 pg TEQ/g dw, and 1.3 pg TEQ/g, respectively), respectively. (2) Although OCDF, 1,2,3,4,6,7,8-HpCDF, OCDD, and 1,2,3,4,6,7,8-HpCDD were the dominant congeners among four environmental sinks, obvious discrepancies of these congener and homologue patterns of PCDD/PCDF were observed still. (3) Significant linear correlations for PCDD/PCDF were observed between the <span class="hlt">gas</span>-particle partition coefficient (K p) and the subcooled liquid vapor pressure (P L (0)) and octanol-<span class="hlt">air</span> partition coefficient (K oa). (4) Fugacity fraction values of <span class="hlt">air</span>-water exchange indicated that most of PCDD/PCDF homologues were dominated by net volatilization from water into <span class="hlt">air</span>. The low-chlorinated PCDD/PCDF (tetra- to hexa-) presented a strong net volatilization from the soil into <span class="hlt">air</span>, while high-chlorinated PCDD/PCDF (hepta- to octa-) were mainly close to equilibrium for <span class="hlt">air</span>-soil exchange.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JThSc..23..535L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JThSc..23..535L"><span>Economic analysis of using above ground <span class="hlt">gas</span> storage devices for compressed <span class="hlt">air</span> energy storage system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Jinchao; Zhang, Xinjing; Xu, Yujie; Chen, Zongyan; Chen, Haisheng; Tan, Chunqing</p> <p>2014-12-01</p> <p>Above ground <span class="hlt">gas</span> storage devices for compressed <span class="hlt">air</span> energy storage (CAES) have three types: <span class="hlt">air</span> storage tanks, <span class="hlt">gas</span> cylinders, and <span class="hlt">gas</span> storage pipelines. A cost model of these <span class="hlt">gas</span> storage devices is established on the basis of whole life cycle cost (LCC) analysis. The optimum parameters of the three types are determined by calculating the theoretical metallic raw material consumption of these three devices and considering the difficulties in manufacture and the influence of <span class="hlt">gas</span> storage device number. The LCCs of the three types are comprehensively analyzed and compared. The result reveal that the cost of the <span class="hlt">gas</span> storage pipeline type is lower than that of the other two types. This study may serve as a reference for designing large-scale CAES systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JNR.....6..241M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JNR.....6..241M"><span>Carbon Nanotubes, Nanocrystal Forms, and Complex Nanoparticle Aggregates in common fuel-<span class="hlt">gas</span> combustion sources and the ambient <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murr, L. E.; Bang, J. J.; Esquivel, E. V.; Guerrero, P. A.; Lopez, D. A.</p> <p>2004-06-01</p> <p>Aggregated multiwall carbon nanotubes (with diameters ranging from ˜3 to 30nm) and related carbon nanocrystal forms ranging in size from 0.4 to 2 μm (average diameter) have been collected in the combustion streams for methane/<span class="hlt">air</span>, natural <span class="hlt">gas/air</span>, and propane <span class="hlt">gas/air</span> flames using a thermal precipitator. Individual particle aggregates were collected on carbon/formvar-coated 3mm nickel grids and examined in a transmission electron microscope, utilizing bright-field imaging, selected-area electron diffraction analysis, and energy-dispersive X-ray spectrometry techniques. The natural <span class="hlt">gas</span> and propane <span class="hlt">gas</span> sources were domestic (kitchen) stoves, and similar particle aggregates collected in the outdoor <span class="hlt">air</span> were correspondingly identified as carbon nanocrystal aggregates and sometimes more complex aggregates of silica nanocrystals intermixed with the carbon nanotubes and other carbon nanocrystals. Finally, and in light of the potential for methane-series <span class="hlt">gas</span> burning as major sources of carbon nanocrystal aggregates in both the indoor and outdoor <span class="hlt">air</span>, data for natural <span class="hlt">gas</span> consumption and corresponding asthma deaths and incidence are examined with a degree of speculation regarding any significance in the correlations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GBioC..21.2015S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GBioC..21.2015S"><span>Constraining global <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange for CO2 with recent bomb 14C measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sweeney, Colm; Gloor, Emanuel; Jacobson, Andrew R.; Key, Robert M.; McKinley, Galen; Sarmiento, Jorge L.; Wanninkhof, Rik</p> <p>2007-06-01</p> <p>The 14CO2 released into the stratosphere during bomb testing in the early 1960s provides a global constraint on <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange of soluble atmospheric gases like CO2. Using the most complete database of dissolved inorganic radiocarbon, DI14C, available to date and a suite of ocean general circulation models in an inverse mode we recalculate the ocean inventory of bomb-produced DI14C in the global ocean and confirm that there is a 25% decrease from previous estimates using older DI14C data sets. Additionally, we find a 33% lower globally averaged <span class="hlt">gas</span> transfer velocity for CO2 compared to previous estimates (Wanninkhof, 1992) using the NCEP/NCAR Reanalysis 1 1954-2000 where the global mean winds are 6.9 m s-1. Unlike some earlier ocean radiocarbon studies, the implied <span class="hlt">gas</span> transfer velocity finally closes the gap between small-scale deliberate tracer studies and global-scale estimates. Additionally, the total inventory of bomb-produced radiocarbon in the ocean is now in agreement with global budgets based on radiocarbon measurements made in the stratosphere and troposphere. Using the implied relationship between wind speed and <span class="hlt">gas</span> transfer velocity ks = 0.27<u102>(Sc/660)-0.5 and standard partial pressure difference climatology of CO2 we obtain an net <span class="hlt">air</span>-sea flux estimate of 1.3 ± 0.5 PgCyr-1 for 1995. After accounting for the carbon transferred from rivers to the deep ocean, our estimate of oceanic uptake (1.8 ± 0.5 PgCyr-1) compares well with estimates based on ocean inventories, ocean transport inversions using ocean <span class="hlt">concentration</span> data, and model simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JPhCS.550a2040B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JPhCS.550a2040B"><span>On the use of pulsed Dielectric Barrier Discharges to control the <span class="hlt">gas</span>-phase composition of atmospheric pressure <span class="hlt">air</span> plasmas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barni, R.; Biganzoli, I.; Dell'Orto, E.; Riccardi, C.</p> <p>2014-11-01</p> <p>We presents results obtained from the numerical simulation of the <span class="hlt">gas</span>-phase chemical kinetics in atmospheric pressure <span class="hlt">air</span> non-equilibrium plasmas. In particular we have addressed the effect of pulsed operation mode of a plane dielectric barrier discharge. It was conjectured that the large difference in the time scales involved in the fast dissociation of oxygen molecules in plasma and their subsequent reactions to produce ozone and nitrogen oxides, makes the presence of a continuously repeated plasma production unnecessary and a waste of electrical power and thus efficiency. In order to test such suggestion we have performed a numerical study of the composition and the temporal evolution of the <span class="hlt">gas</span>-phase of atmospheric pressure <span class="hlt">air</span> non-equilibrium plasmas. Comparison with experimental findings in a dielectric barrier discharge with an electrode configuration symmetrical and almost ideally plane is briefly addressed too, using plasma diagnostics to extract the properties of the single micro-discharges and a sensor to measure the <span class="hlt">concentration</span> of ozone produced by the plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28413805','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28413805"><span>Release of Airborne Polychlorinated Biphenyls from New Bedford Harbor Results in Elevated <span class="hlt">Concentrations</span> in the Surrounding <span class="hlt">Air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Martinez, Andres; Hadnott, Bailey N; Awad, Andrew M; Herkert, Nicholas J; Tomsho, Kathryn; Basra, Komal; Scammell, Madeleine K; Heiger-Bernays, Wendy; Hornbuckle, Keri C</p> <p>2017-04-11</p> <p>Qualitatively and quantitatively, we have demonstrated that airborne polychlorinated biphenyl (PCB) <span class="hlt">concentrations</span> in the <span class="hlt">air</span> surrounding New Bedford Harbor (NBH) are caused by its water PCB emissions. We measured airborne PCBs at 18 homes and businesses near NBH in 2015, with values ranging from 0.4 to 38 ng m -3 , with a very strong Aroclor 1242/1016 signal that is most pronounced closest to the harbor and reproducible over three sampling rounds. Using U.S. Environmental Protection Agency (U.S. EPA) water PCB data from 2015 and local meteorology, we predicted <span class="hlt">gas</span>-phase fluxes of PCBs from 160 to 1200 μg m -2 day -1 . Fluxes were used as emissions for AERMOD, a widely applied U.S. EPA atmospheric dispersion model, to predict airborne PCB <span class="hlt">concentrations</span>. The AERMOD predictions were within a factor of 2 of the field measurements. PCB emission from NBH (110 kg year -1 , average 2015) is the largest reported source of airborne PCBs from natural waters in North America, and the source of high ambient <span class="hlt">air</span> PCB <span class="hlt">concentrations</span> in locations close to NBH. It is likely that NBH has been an important source of airborne PCBs since it was contaminated with Aroclors more than 60 years ago.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5441706','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5441706"><span><span class="hlt">Air</span> quality, health, and climate implications of China’s synthetic natural <span class="hlt">gas</span> development</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Qin, Yue; Wagner, Fabian; Scovronick, Noah; Yang, Junnan; Zhu, Tong; Mauzerall, Denise L.</p> <p>2017-01-01</p> <p>Facing severe <span class="hlt">air</span> pollution and growing dependence on natural <span class="hlt">gas</span> imports, the Chinese government plans to increase coal-based synthetic natural <span class="hlt">gas</span> (SNG) production. Although displacement of coal with SNG benefits <span class="hlt">air</span> quality, it increases CO2 emissions. Due to variations in <span class="hlt">air</span> pollutant and CO2 emission factors and energy efficiencies across sectors, coal replacement with SNG results in varying degrees of <span class="hlt">air</span> quality benefits and climate penalties. We estimate <span class="hlt">air</span> quality, human health, and climate impacts of SNG substitution strategies in 2020. Using all production of SNG in the residential sector results in an annual decrease of ∼32,000 (20,000 to 41,000) outdoor-<span class="hlt">air</span>-pollution-associated premature deaths, with ranges determined by the low and high estimates of the health risks. If changes in indoor/household <span class="hlt">air</span> pollution were also included, the decrease would be far larger. SNG deployment in the residential sector results in nearly 10 and 60 times greater reduction in premature mortality than if it is deployed in the industrial or power sectors, respectively. Due to inefficiencies in current household coal use, utilization of SNG in the residential sector results in only 20 to 30% of the carbon penalty compared with using it in the industrial or power sectors. Even if carbon capture and storage is used in SNG production with today’s technology, SNG emits 22 to 40% more CO2 than the same amount of conventional <span class="hlt">gas</span>. Among the SNG deployment strategies we evaluate, allocating currently planned SNG to households provides the largest <span class="hlt">air</span> quality and health benefits with the smallest carbon penalties. PMID:28438993</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28347612','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28347612"><span><span class="hlt">Air</span> ionization as a control technology for off-<span class="hlt">gas</span> emissions of volatile organic compounds.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Ki-Hyun; Szulejko, Jan E; Kumar, Pawan; Kwon, Eilhann E; Adelodun, Adedeji A; Reddy, Police Anil Kumar</p> <p>2017-06-01</p> <p>High energy electron-impact ionizers have found applications mainly in industry to reduce off-<span class="hlt">gas</span> emissions from waste <span class="hlt">gas</span> streams at low cost and high efficiency because of their ability to oxidize many airborne organic pollutants (e.g., volatile organic compounds (VOCs)) to CO 2 and H 2 O. Applications of <span class="hlt">air</span> ionizers in indoor <span class="hlt">air</span> quality management are limited due to poor removal efficiency and production of noxious side products, e.g., ozone (O 3 ). In this paper, we provide a critical evaluation of the pollutant removal performance of <span class="hlt">air</span> ionizing system through comprehensive review of the literature. In particular, we focus on removal of VOCs and odorants. We also discuss the generation of unwanted <span class="hlt">air</span> ionization byproducts such as O 3 , NOx, and VOC oxidation intermediates that limit the use of <span class="hlt">air</span>-ionizers in indoor <span class="hlt">air</span> quality management. Copyright © 2017. Published by Elsevier Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=65873&keyword=rate+AND+chemistry+AND+experiment&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=65873&keyword=rate+AND+chemistry+AND+experiment&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span><span class="hlt">GAS</span> CHROMATOGRAPHIC TECHNIQUES FOR THE MEASUREMENT OF ISOPRENE IN <span class="hlt">AIR</span></span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The chapter discusses <span class="hlt">gas</span> chromatographic techniques for measuring isoprene in <span class="hlt">air</span>. Such measurement basically consists of three parts: (1) collection of sufficient sample volume for representative and accurate quantitation, (2) separation (if necessary) of isoprene from interfer...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE10161E..0OJ','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE10161E..0OJ"><span>An electronic nose for quantitative determination of <span class="hlt">gas</span> <span class="hlt">concentrations</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jasinski, Grzegorz; Kalinowski, Paweł; Woźniak, Łukasz</p> <p>2016-11-01</p> <p>The practical application of human nose for fragrance recognition is severely limited by the fact that our sense of smell is subjective and gets tired easily. Consequently, there is considerable need for an instrument that can be a substitution of the human sense of smell. Electronic nose devices from the mid 1980s are used in growing number of applications. They comprise an array of several electrochemical <span class="hlt">gas</span> sensors with partial specificity and a pattern recognition algorithms. Most of such systems, however, is only used for qualitative measurements. In this article usage of such system in quantitative determination of <span class="hlt">gas</span> <span class="hlt">concentration</span> is demonstrated. Electronic nose consist of a sensor array with eight commercially available Taguchi type <span class="hlt">gas</span> sensor. Performance of three different pattern recognition algorithms is compared, namely artificial neural network, partial least squares regression and support vector machine regression. The electronic nose is used for ammonia and nitrogen dioxide <span class="hlt">concentration</span> determination.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.B22F..02P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B22F..02P"><span>Method to make accurate <span class="hlt">concentration</span> and isotopic measurements for small <span class="hlt">gas</span> samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palmer, M. R.; Wahl, E.; Cunningham, K. L.</p> <p>2013-12-01</p> <p>Carbon isotopic ratio measurements of CO2 and CH4 provide valuable insight into carbon cycle processes. However, many of these studies, like soil <span class="hlt">gas</span>, soil flux, and water head space experiments, provide very small <span class="hlt">gas</span> sample volumes, too small for direct measurement by current constant-flow Cavity Ring-Down (CRDS) isotopic analyzers. Previously, we addressed this issue by developing a sample introduction module which enabled the isotopic ratio measurement of 40ml samples or smaller. However, the system, called the Small Sample Isotope Module (SSIM), does dilute the sample during the delivery with inert carrier <span class="hlt">gas</span> which causes a ~5% reduction in <span class="hlt">concentration</span>. The isotopic ratio measurements are not affected by this small dilution, but researchers are naturally interested accurate <span class="hlt">concentration</span> measurements. We present the accuracy and precision of a new method of using this delivery module which we call 'double injection.' Two portions of the 40ml of the sample (20ml each) are introduced to the analyzer, the first injection of which flushes out the diluting <span class="hlt">gas</span> and the second injection is measured. The accuracy of this new method is demonstrated by comparing the <span class="hlt">concentration</span> and isotopic ratio measurements for a <span class="hlt">gas</span> sampled directly and that same <span class="hlt">gas</span> measured through the SSIM. The data show that the CO2 <span class="hlt">concentration</span> measurements were the same within instrument precision. The isotopic ratio precision (1σ) of repeated measurements was 0.16 permil for CO2 and 1.15 permil for CH4 at ambient <span class="hlt">concentrations</span>. This new method provides a significant enhancement in the information provided by small samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPIE10562E..5ZV','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPIE10562E..5ZV"><span>Higs-instrument: design and demonstration of a high performance <span class="hlt">gas</span> <span class="hlt">concentration</span> imager</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Verlaan, A. L.; Klop, W. A.; Visser, H.; van Brug, H.; Human, J.</p> <p>2017-09-01</p> <p>Climate change and environmental conditions are high on the political agenda of international governments. Laws and regulations are being setup all around the world to improve the <span class="hlt">air</span> quality and to reduce the impact. The growth of a number of trace gasses, including CO2, Methane and NOx are especially interesting due to their environmental impact. The regulations made are being based on both models and measurements of the trend of those trace gases over the years. Now the regulations are in place also enforcement and therewith measurements become more and more important. Instruments enabling high spectral and spatial resolution as well as high accurate measurements of trace gases are required to deliver the necessary inputs. Nowadays those measurements are usually performed by space based spectrometers. The requirement for high spectral resolution and measurement accuracy significantly increases the size of the instruments. As a result the instrument and satellite becomes very expensive to develop and to launch. Specialized instruments with a small volume and the required performance will offer significant advantages in both cost and performance. Huib's Innovative <span class="hlt">Gas</span> Sensor (HIGS, named after its inventor Huib Visser), currently being developed at TNO is an instrument that achieves exactly that. Designed to measure only a single <span class="hlt">gas</span> <span class="hlt">concentration</span>, opposed to deriving it from a spectrum, it achieves high performance within a small design volume. The instrument enables instantaneous imaging of the <span class="hlt">gas</span> distribution of the selected <span class="hlt">gas</span>. An instrument demonstrator has been developed for NO2 detection. Laboratory measurements proved the measurement technique to be successful. An on-sky measurement campaign is in preparation. This paper addresses both the instrument design as well as the demonstrated performances.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22439940','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22439940"><span>Fate of hazardous <span class="hlt">air</span> pollutants in oxygen-fired coal combustion with different flue <span class="hlt">gas</span> recycling.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhuang, Ye; Pavlish, John H</p> <p>2012-04-17</p> <p>Experiments were performed to characterize transformation and speciation of hazardous <span class="hlt">air</span> pollutants (HAPs), including SO(2)/SO(3), NO(x), HCl, particulate matter, mercury, and other trace elements in oxygen-firing bituminous coal with recirculation flue <span class="hlt">gas</span> (RFG) from 1) an electrostatic precipitator outlet or 2) a wet scrubber outlet. The experimental results showed that oxycombustion with RFG generated a flue <span class="hlt">gas</span> with less volume and containing HAPs at higher levels, while the actual emissions of HAPs per unit of energy produced were much less than that of <span class="hlt">air</span>-blown combustion. NO(x) reduction was achieved in oxycombustion because of the elimination of nitrogen and the destruction of NO in the RFG. The elevated SO(2)/SO(3) in flue <span class="hlt">gas</span> improved sulfur self-retention. SO(3) vapor could reach its dew point in the flue <span class="hlt">gas</span> with high moisture, which limits the amount of SO(3) vapor in flue <span class="hlt">gas</span> and possibly induces material corrosion. Most nonvolatile trace elements were less enriched in fly ash in oxycombustion than <span class="hlt">air</span>-firing because of lower oxycombustion temperatures occurring in the present study. Meanwhile, Hg and Se were found to be enriched on submicrometer fly ash at higher levels in oxy-firing than in <span class="hlt">air</span>-blown combustion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21240707','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21240707"><span>Effect of biomass open burning on particulate matter and polycyclic aromatic hydrocarbon <span class="hlt">concentration</span> levels and PAH dry deposition in ambient <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chiu, Jui C; Shen, Yun H; Li, Hsing W; Chang, Shun S; Wang, Lin C; Chang-Chien, Guo P</p> <p>2011-01-01</p> <p>The objectives of the present study were to investigate particulate matter (PM) and polycyclic aromatic hydrocarbon (PAH) <span class="hlt">concentrations</span> in ambient <span class="hlt">air</span> during rice straw open burning and non-open burning periods. In the ambient <span class="hlt">air</span> of a rice field, the mean PM <span class="hlt">concentration</span> during and after an open burning event were 1828 and 102 μg m⁻³, respectively, which demonstrates that during a rice field open burning event, the PM <span class="hlt">concentration</span> in the ambient <span class="hlt">air</span> of rice field is over 17 times higher than that of the non-open burning period. During an open burning event, the mean total PAH and total toxic equivalence (BaP(eq)) <span class="hlt">concentrations</span> in the ambient <span class="hlt">air</span> of a rice field were 7206 ng m⁻³ and 10.3 ng m⁻³, respectively, whereas after the open burning event, they were 376 ng m⁻³ and 1.50 ng m⁻³, respectively. Open burning thus increases total PAH and total BaP(eq) <span class="hlt">concentrations</span> by 19-fold and 6.8-fold, respectively. During a rice straw open burning event, in the ambient <span class="hlt">air</span> of a rice field, the mean dry deposition fluxes of total PAHs and total BaP(eq) were 1222 μg m⁻² day⁻¹ and 4.80 μg m⁻² day⁻¹, respectively, which are approximately 60- and 3-fold higher than those during the non-open burning period, respectively. During the non-open burning period, particle-bound PAHs contributed 79.2-84.2% of total dry deposition fluxes (<span class="hlt">gas</span> + particle) of total PAHs. However, an open burning event increases the contribution to total PAH dry deposition by particle-bound PAHs by up to 85.9-95.5%. The results show that due to the increased amount of PM in the ambient <span class="hlt">air</span> resulting from rice straw open burning, particle-bound PAHs contributed more to dry deposition fluxes of total PAHs than they do during non-open burning periods. The results show that biomass (rice straw) open burning is an important PAH emission source that significantly increases both PM and PAH <span class="hlt">concentration</span> levels and PAH dry deposition in ambient <span class="hlt">air</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GMD....10.2057M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GMD....10.2057M"><span>Historical greenhouse <span class="hlt">gas</span> <span class="hlt">concentrations</span> for climate modelling (CMIP6)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meinshausen, Malte; Vogel, Elisabeth; Nauels, Alexander; Lorbacher, Katja; Meinshausen, Nicolai; Etheridge, David M.; Fraser, Paul J.; Montzka, Stephen A.; Rayner, Peter J.; Trudinger, Cathy M.; Krummel, Paul B.; Beyerle, Urs; Canadell, Josep G.; Daniel, John S.; Enting, Ian G.; Law, Rachel M.; Lunder, Chris R.; O'Doherty, Simon; Prinn, Ron G.; Reimann, Stefan; Rubino, Mauro; Velders, Guus J. M.; Vollmer, Martin K.; Wang, Ray H. J.; Weiss, Ray</p> <p>2017-05-01</p> <p>Atmospheric greenhouse <span class="hlt">gas</span> (GHG) <span class="hlt">concentrations</span> are at unprecedented, record-high levels compared to the last 800 000 years. Those elevated GHG <span class="hlt">concentrations</span> warm the planet and - partially offset by net cooling effects by aerosols - are largely responsible for the observed warming over the past 150 years. An accurate representation of GHG <span class="hlt">concentrations</span> is hence important to understand and model recent climate change. So far, community efforts to create composite datasets of GHG <span class="hlt">concentrations</span> with seasonal and latitudinal information have focused on marine boundary layer conditions and recent trends since the 1980s. Here, we provide consolidated datasets of historical atmospheric <span class="hlt">concentrations</span> (mole fractions) of 43 GHGs to be used in the Climate Model Intercomparison Project - Phase 6 (CMIP6) experiments. The presented datasets are based on AGAGE and NOAA networks, firn and ice core data, and archived <span class="hlt">air</span> data, and a large set of published studies. In contrast to previous intercomparisons, the new datasets are latitudinally resolved and include seasonality. We focus on the period 1850-2014 for historical CMIP6 runs, but data are also provided for the last 2000 years. We provide consolidated datasets in various spatiotemporal resolutions for carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), as well as 40 other GHGs, namely 17 ozone-depleting substances, 11 hydrofluorocarbons (HFCs), 9 perfluorocarbons (PFCs), sulfur hexafluoride (SF6), nitrogen trifluoride (NF3) and sulfuryl fluoride (SO2F2). In addition, we provide three equivalence species that aggregate <span class="hlt">concentrations</span> of GHGs other than CO2, CH4 and N2O, weighted by their radiative forcing efficiencies. For the year 1850, which is used for pre-industrial control runs, we estimate annual global-mean surface <span class="hlt">concentrations</span> of CO2 at 284.3 ppm, CH4 at 808.2 ppb and N2O at 273.0 ppb. The data are available at <a href="https://esgf-node.llnl.gov/search/input4mips/" target</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4290627','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4290627"><span>Historical Occupational Trichloroethylene <span class="hlt">Air</span> <span class="hlt">Concentrations</span> Based on Inspection Measurements From Shanghai, China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Friesen, Melissa C.; Locke, Sarah J.; Chen, Yu-Cheng; Coble, Joseph B.; Stewart, Patricia A.; Ji, Bu-Tian; Bassig, Bryan; Lu, Wei; Xue, Shouzheng; Chow, Wong-Ho; Lan, Qing; Purdue, Mark P.; Rothman, Nathaniel; Vermeulen, Roel</p> <p>2015-01-01</p> <p>Purpose: Trichloroethylene (TCE) is a carcinogen that has been linked to kidney cancer and possibly other cancer sites including non-Hodgkin lymphoma. Its use in China has increased since the early 1990s with China’s growing metal, electronic, and telecommunications industries. We examined historical occupational TCE <span class="hlt">air</span> <span class="hlt">concentration</span> patterns in a database of TCE inspection measurements collected in Shanghai, China to identify temporal trends and broad contrasts among occupations and industries. Methods: Using a database of 932 short-term, area TCE <span class="hlt">air</span> inspection measurements collected in Shanghai worksites from 1968 through 2000 (median year 1986), we developed mixed-effects models to evaluate job-, industry-, and time-specific TCE <span class="hlt">air</span> <span class="hlt">concentrations</span>. Results: Models of TCE <span class="hlt">air</span> <span class="hlt">concentrations</span> from Shanghai work sites predicted that exposures decreased 5–10% per year between 1968 and 2000. Measurements collected near launderers and dry cleaners had the highest predicted geometric means (GM for 1986 = 150–190mg m−3). The majority (53%) of the measurements were collected in metal treatment jobs. In a model restricted to measurements in metal treatment jobs, predicted GMs for 1986 varied 35-fold across industries, from 11mg m−3 in ‘other metal products/repair’ industries to 390mg m–3 in ‘ships/aircrafts’ industries. Conclusions: TCE workplace <span class="hlt">air</span> <span class="hlt">concentrations</span> appeared to have dropped over time in Shanghai, China between 1968 and 2000. Understanding differences in TCE <span class="hlt">concentrations</span> across time, occupations, and industries may assist future epidemiologic studies in China. PMID:25180291</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA095572','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA095572"><span>The Effects of Scavenging on Waste Methoxyflurane <span class="hlt">Concentrations</span> in Veterinary Operating Room <span class="hlt">Air</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1981-01-01</p> <p>Afl-AO5 572 <span class="hlt">AIR</span> FORCE OCCUPATIONAL AND ENVIRONMENTAL H4EALTH LAS -ETC F/S 6120 TIE EFFECTS OF SCAVENGING ON WASTE METHOXYFLURANE CONCENTRATIOH-ETC...REPRINT The Effects of Scavenging on Waste Methoxyflurane <span class="hlt">Concentrations</span> in Veterinary Operating Room <span class="hlt">Air</span> Approved for public release; distribution...Waste Methoxyflurane Fnal y t <span class="hlt">Concentrations</span> ir Veterinary Operating Room <span class="hlt">Air</span>, 6.PROMN _6._PERFORMIN oIG. REPORT NUMBER 7. AUTOR~s)B. CONTRACT OR GRANT</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29484620','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29484620"><span><span class="hlt">Air</span> pollution from industrial waste <span class="hlt">gas</span> emissions is associated with cancer incidences in Shanghai, China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cong, Xiaowei</p> <p>2018-05-01</p> <p>Outdoor <span class="hlt">air</span> pollution may be associated with cancer risk at different sites. This study sought to investigate outdoor <span class="hlt">air</span> pollution from waste <span class="hlt">gas</span> emission effects on multiple cancer incidences in a retrospective population-based study in Shanghai, China. Trends in cancer incidence for males and females and trends in waste <span class="hlt">gas</span> emissions for the total waste <span class="hlt">gas</span>, industrial waste <span class="hlt">gas</span>, other waste <span class="hlt">gas</span>, SO 2 , and soot were investigated between 1983 and 2010 in Shanghai, China. Regression models after adjusting for confounding variables were constructed to estimate associations between waste <span class="hlt">gas</span> emissions and multiple cancer incidences in the whole group and stratified by sex, Engel coefficient, life expectancy, and number of doctors per 10,000 populations to further explore whether changes of waste <span class="hlt">gas</span> emissions were associated with multiple cancer incidences. More than 550,000 new cancer patients were enrolled and reviewed. Upward trends in multiple cancer incidences for males and females and in waste <span class="hlt">gas</span> emissions were observed from 1983 to 2010 in Shanghai, China. Waste <span class="hlt">gas</span> emissions came mainly from industrial waste <span class="hlt">gas</span>. Waste <span class="hlt">gas</span> emissions was significantly positively associated with cancer incidence of salivary gland, small intestine, colorectal, anus, gallbladder, thoracic organs, connective and soft tissue, prostate, kidney, bladder, thyroid, non-Hodgkin's lymphoma, lymphatic leukemia, myeloid leukemia, and other unspecified sites (all p < 0.05). Negative association between waste <span class="hlt">gas</span> emissions and the esophagus cancer incidence was observed (p < 0.05). The results of the whole group were basically consistent with the results of the stratified analysis. The results from this retrospective population-based study suggest ambient <span class="hlt">air</span> pollution from waste <span class="hlt">gas</span> emissions was associated with multiple cancer incidences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......178W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......178W"><span>Aqueous turbulence structure immediately adjacent to the <span class="hlt">air</span> - water interface and interfacial <span class="hlt">gas</span> exchange</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Binbin</p> <p></p> <p><span class="hlt">Air</span>-sea interaction and the interfacial exchange of <span class="hlt">gas</span> across the <span class="hlt">air</span>-water interface are of great importance in coupled atmospheric-oceanic environmental systems. Aqueous turbulence structure immediately adjacent to the <span class="hlt">air</span>-water interface is the combined result of wind, surface waves, currents and other environmental forces and plays a key role in energy budgets, <span class="hlt">gas</span> fluxes and hence the global climate system. However, the quantification of turbulence structure sufficiently close to the <span class="hlt">air</span>-water interface is extremely difficult. The physical relationship between interfacial <span class="hlt">gas</span> exchange and near surface turbulence remains insufficiently investigated. This dissertation aims to measure turbulence in situ in a complex environmental forcing system on Lake Michigan and to reveal the relationship between turbulent statistics and the CO2 flux across the <span class="hlt">air</span>-water interface. The major objective of this dissertation is to investigate the physical control of the interfacial <span class="hlt">gas</span> exchange and to provide a universal parameterization of <span class="hlt">gas</span> transfer velocity from environmental factors, as well as to propose a mechanistic model for the global CO2 flux that can be applied in three dimensional climate-ocean models. Firstly, this dissertation presents an advanced measurement instrument, an in situ free floating Particle Image Velocimetry (FPIV) system, designed and developed to investigate the small scale turbulence structure immediately below the <span class="hlt">air</span>-water interface. Description of hardware components, design of the system, measurement theory, data analysis procedure and estimation of measurement error were provided. Secondly, with the FPIV system, statistics of small scale turbulence immediately below the <span class="hlt">air</span>-water interface were investigated under a variety of environmental conditions. One dimensional wave-number spectrum and structure function sufficiently close to the water surface were examined. The vertical profiles of turbulent dissipation rate were intensively studied</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21619278','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21619278"><span>An analytical method for trifluoroacetic Acid in water and <span class="hlt">air</span> samples using headspace <span class="hlt">gas</span> chromatographic determination of the methyl ester.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zehavi, D; Seiber, J N</p> <p>1996-10-01</p> <p>An analytical method has been developed for the determination of trace levels of trifluoroacetic acid (TFA), an atmospheric breakdown product of several of the hydrofluorocarbon (HFC) and hydrochlorofluorocarbon (HCFC) replacements for the chlorofluorocarbon (CFC) refrigerants, in water and <span class="hlt">air</span>. TFA is derivatized to the volatile methyl trifluoroacetate (MTFA) and determined by automated headspace <span class="hlt">gas</span> chromatography (HSGC) with electron-capture detection or manual HSGC using GC/MS in the selected ion monitoring (SIM) mode. The method is based on the reaction of an aqueous sample containing TFA with dimethyl sulfate (DMS) in <span class="hlt">concentrated</span> sulfuric acid in a sealed headspace vial under conditions favoring distribution of MTFA to the vapor phase. Water samples are prepared by evaporative <span class="hlt">concentration</span>, during which TFA is retained as the anion, followed by extraction with diethyl ether of the acidified sample and then back-extraction of TFA (as the anion) in aqueous bicarbonate solution. The extraction step is required for samples with a relatively high background of other salts and organic materials. <span class="hlt">Air</span> samples are collected in sodium bicarbonate-glycerin-coated glass denuder tubes and prepared by rinsing the denuder contents with water to form an aqueous sample for derivatization and analysis. Recoveries of TFA from spiked water, with and without evaporative <span class="hlt">concentration</span>, and from spiked <span class="hlt">air</span> were quantitative, with estimated detection limits of 10 ng/mL (unconcentrated) and 25 pg/mL (<span class="hlt">concentrated</span> 250 mL:1 mL) for water and 1 ng/m(3) (72 h at 5 L/min) for <span class="hlt">air</span>. Several environmental <span class="hlt">air</span>, fogwater, rainwater, and surface water samples were successfully analyzed; many showed the presence of TFA.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1983/0589/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1983/0589/report.pdf"><span>Helium <span class="hlt">concentrations</span> in soil <span class="hlt">gas</span> of the Ely and Delta 1 degree x 2 degrees quadrangles. Basin and Range Province</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Reimer, G.M.; Bowles, C.G.</p> <p>1983-01-01</p> <p>A reconnaissance soil-<span class="hlt">gas</span> helium survey was made of the Ely, Nevada and Delta, Utah 1? x 2? quadrangles in the Basin and Range Province. Helium <span class="hlt">concentrations</span> in 510 samples ranged from -147 to 441 ppb He with respect to ambient <span class="hlt">air</span>. The median helium value for the study area was 36 ppb. <span class="hlt">Concentrations</span> of more than 100 ppb He, and less than -20 ppb He, occur more commonly in the Ely Quadrangle and are especially numerous in the western one-half of this quadrangle. The data are presented both in figures and tables, and some of the geologic factors that may affect the helium distribution are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27977141','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27977141"><span>Decabrominated Diphenyl Ethers (BDE-209) in Chinese and Global <span class="hlt">Air</span>: Levels, <span class="hlt">Gas</span>/Particle Partitioning, and Long-Range Transport: Is Long-Range Transport of BDE-209 Really Governed by the Movement of Particles?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Yi-Fan; Qiao, Li-Na; Ren, Nan-Qi; Sverko, Ed; Mackay, Donald; Macdonald, Robie W</p> <p>2017-01-17</p> <p>In this paper, we report <span class="hlt">air</span> <span class="hlt">concentrations</span> of BDE-209 in both <span class="hlt">gas</span>- and particle-phases across China. The annual mean <span class="hlt">concentrations</span> of BDE-209 were from below detection limit (BDL) to 77.0 pg·m -3 in the <span class="hlt">gas</span>-phase and 1.06-728 pg·m -3 in the particle-phase. Among the nine PBDEs measured, BDE-209 is the dominant congener in Chinese atmosphere in both <span class="hlt">gas</span> and particle phases. We predicted the partitioning behavior of BDE-209 in <span class="hlt">air</span> using our newly developed steady state equation, and the results matched the monitoring data worldwide very well. It was found that the logarithm of the partition quotient of BDE-209 is a constant, and equal to -1.53 under the global ambient temperature range (from -50 to +50 °C). The gaseous fractions of BDE-209 in <span class="hlt">air</span> depends on the <span class="hlt">concentration</span> of total suspended particle (TSP). The most important conclusion derived from this study is that, BDE-209, like other semivolatile organic compounds (SVOCs), cannot be sorbed entirely to atmospheric particles; and there is a significant amount of gaseous BDE-209 in global atmosphere, which is subject to long-range atmospheric transport (LRAT). Therefore, it is not surprising that BDE-209 can enter the Arctic through LRAT mainly by <span class="hlt">air</span> transport rather than by particle movement. This is a significant advancement in understanding the global transport process and the pathways entering the Arctic for chemicals with low volatility and high octanol-<span class="hlt">air</span> partition coefficients, such as BDE-209.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3990720','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3990720"><span>Coal-Packed Methane Biofilter for Mitigation of Green House <span class="hlt">Gas</span> Emissions from Coal Mine Ventilation <span class="hlt">Air</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Limbri, Hendy; Gunawan, Cindy; Thomas, Torsten; Smith, Andrew; Scott, Jason; Rosche, Bettina</p> <p>2014-01-01</p> <p>Methane emitted by coal mine ventilation <span class="hlt">air</span> (MVA) is a significant greenhouse <span class="hlt">gas</span>. A mitigation strategy is the oxidation of methane to carbon dioxide, which is approximately twenty-one times less effective at global warming than methane on a mass-basis. The low non-combustible methane <span class="hlt">concentrations</span> at high MVA flow rates call for a catalytic strategy of oxidation. A laboratory-scale coal-packed biofilter was designed and partially removed methane from humidified <span class="hlt">air</span> at flow rates between 0.2 and 2.4 L min−1 at 30°C with nutrient solution added every three days. Methane oxidation was catalysed by a complex community of naturally-occurring microorganisms, with the most abundant member being identified by 16S rRNA gene sequence as belonging to the methanotrophic genus Methylocystis. Additional inoculation with a laboratory-grown culture of Methylosinus sporium, as investigated in a parallel run, only enhanced methane consumption during the initial 12 weeks. The greatest level of methane removal of 27.2±0.66 g methane m−3 empty bed h−1 was attained for the non-inoculated system, which was equivalent to removing 19.7±2.9% methane from an inlet <span class="hlt">concentration</span> of 1% v/v at an inlet <span class="hlt">gas</span> flow rate of 1.6 L min−1 (2.4 min empty bed residence time). These results show that low-cost coal packing holds promising potential as a suitable growth surface and contains methanotrophic microorganisms for the catalytic oxidative removal of methane. PMID:24743729</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/871453','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/871453"><span>Method and apparatus for controlling fuel/<span class="hlt">air</span> mixture in a lean burn engine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Kubesh, John Thomas; Dodge, Lee Gene; Podnar, Daniel James</p> <p>1998-04-07</p> <p>The system for controlling the fuel/<span class="hlt">air</span> mixture supplied to a lean burn engine when operating on natural <span class="hlt">gas</span>, gasoline, hydrogen, alcohol, propane, butane, diesel or any other fuel as desired. As specific humidity of <span class="hlt">air</span> supplied to the lean burn engine increases, the oxygen <span class="hlt">concentration</span> of exhaust <span class="hlt">gas</span> discharged by the engine for a given equivalence ratio will decrease. Closed loop fuel control systems typically attempt to maintain a constant exhaust <span class="hlt">gas</span> oxygen <span class="hlt">concentration</span>. Therefore, the decrease in the exhaust <span class="hlt">gas</span> oxygen <span class="hlt">concentration</span> resulting from increased specific humidity will often be improperly attributed to an excessive supply of fuel and the control system will incorrectly reduce the amount of fuel supplied to the engine. Also, the minimum fuel/<span class="hlt">air</span> equivalence ratio for a lean burn engine to avoid misfiring will increase as specific humidity increases. A relative humidity sensor to allow the control system to provide a more enriched fuel/<span class="hlt">air</span> mixture at high specific humidity levels. The level of specific humidity may be used to compensate an output signal from a universal exhaust <span class="hlt">gas</span> oxygen sensor for changing oxygen <span class="hlt">concentrations</span> at a desired equivalence ratio due to variation in specific humidity specific humidity. As a result, the control system will maintain the desired efficiency, low exhaust emissions and power level for the associated lean burn engine regardless of the specific humidity level of intake <span class="hlt">air</span> supplied to the lean burn engine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26845179','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26845179"><span>Environmental contamination due to shale <span class="hlt">gas</span> development.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Annevelink, M P J A; Meesters, J A J; Hendriks, A J</p> <p>2016-04-15</p> <p>Shale <span class="hlt">gas</span> development potentially contaminates both <span class="hlt">air</span> and water compartments. To assist in governmental decision-making on future explorations, we reviewed scattered information on activities, emissions and <span class="hlt">concentrations</span> related to shale <span class="hlt">gas</span> development. We compared <span class="hlt">concentrations</span> from monitoring programmes to quality standards as a first indication of environmental risks. Emissions could not be estimated accurately because of incomparable and insufficient data. <span class="hlt">Air</span> and water <span class="hlt">concentrations</span> range widely. Poor wastewater treatment posed the highest risk with <span class="hlt">concentrations</span> exceeding both Natural Background Values (NBVs) by a factor 1000-10,000 and Lowest Quality Standards (LQSs) by a factor 10-100. <span class="hlt">Concentrations</span> of salts, metals, volatile organic compounds (VOCs) and hydrocarbons exceeded aquatic ecotoxicological water standards. Future research must focus on measuring aerial and aquatic emissions of toxic chemicals, generalisation of experimental setups and measurement technics and further human and ecological risk assessment. Copyright © 2016 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUSM.H33C..06B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUSM.H33C..06B"><span><span class="hlt">Air</span> Sparging Versus <span class="hlt">Gas</span> Saturated Water Injection for Remediation of Volatile LNAPL in the Borden Aquifer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barker, J.; Nelson, L.; Doughty, C.; Thomson, N.; Lambert, J.</p> <p>2009-05-01</p> <p>In the shallow, rather homogeneous, unconfined Borden sand aquifer, field trials of <span class="hlt">air</span> sparging (Tomlinson et al., 2003) and pulsed <span class="hlt">air</span> sparging (Lambert et al., 2009) have been conducted, the latter to remediate a residual gasoline source emplaced below the water table. As well, a supersaturated (with CO2) water injection (SWI) technology, using the inVentures inFusion system, has been trialed in two phases: 1. in the uncontaminated sand aquifer to evaluate the radius of influence, extent of lateral <span class="hlt">gas</span> movement and <span class="hlt">gas</span> saturation below the water table, and 2. in a sheet pile cell in the Borden aquifer to evaluate the recovery of volatile hydrocarbon components (pentane and hexane) of an LNAPL emplaced below the water table (Nelson et al., 2008). The SWI injects water supersaturated with CO2. The supersaturated injected water moves laterally away from the sparge point, releasing CO2 over a wider area than does <span class="hlt">gas</span> sparging from a single well screen. This presentation compares these two techniques in terms of their potential for remediating volatile NAPL components occurring below the water table in a rather homogeneous sand aquifer. <span class="hlt">Air</span> sparging created a significantly greater <span class="hlt">air</span> saturation in the vicinity of the sparge well than did the CO2 system (60 percent versus 16 percent) in the uncontaminated Borden aquifer. However, SWI pushed water, still supersaturated with CO2, up to about 2.5 m from the injection well. This would seem to provide a considerable advantage over <span class="hlt">air</span> sparging from a point, in that <span class="hlt">gas</span> bubbles are generated at a much larger radius from the point of injection with SWI and so should involve additional <span class="hlt">gas</span> pathways through a residual NAPL. Overall, <span class="hlt">air</span> sparging created a greater area of influence, defined by measurable <span class="hlt">air</span> saturation in the aquifer, but <span class="hlt">air</span> sparging also injected about 12 times more <span class="hlt">gas</span> than was injected in the SWI trials. The pulsed <span class="hlt">air</span> sparging at Borden (Lambert et al.) removed about 20 percent (4.6 kg) of gasoline</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70102289','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70102289"><span><span class="hlt">Air</span>-water <span class="hlt">gas</span> exchange and CO2 flux in a mangrove-dominated estuary</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ho, David T.; Ferrón, Sara; Engel, Victor C.; Larsen, Laurel G.; Barr, Jordan G.</p> <p>2014-01-01</p> <p>Mangrove forests are highly productive ecosystems, but the fate of mangrove-derived carbon remains uncertain. Part of that uncertainty stems from the fact that <span class="hlt">gas</span> transfer velocities in mangrove-surrounded waters are not well determined, leading to uncertainty in <span class="hlt">air</span>-water CO2 fluxes. Two SF6 tracer release experiments were conducted to determine <span class="hlt">gas</span> transfer velocities (k(600) = 8.3 ± 0.4 and 8.1 ± 0.6 cm h−1), along with simultaneous measurements of pCO2 to determine the <span class="hlt">air</span>-water CO2 fluxes from Shark River, Florida (232.11 ± 23.69 and 171.13 ± 20.28 mmol C m−2 d−1), an estuary within the largest contiguous mangrove forest in North America. The <span class="hlt">gas</span> transfer velocity results are consistent with turbulent kinetic energy dissipation measurements, indicating a higher rate of turbulence and <span class="hlt">gas</span> exchange than predicted by commonly used wind speed/<span class="hlt">gas</span> exchange parameterizations. The results have important implications for carbon fluxes in mangrove ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25180291','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25180291"><span>Historical occupational trichloroethylene <span class="hlt">air</span> <span class="hlt">concentrations</span> based on inspection measurements from Shanghai, China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Friesen, Melissa C; Locke, Sarah J; Chen, Yu-Cheng; Coble, Joseph B; Stewart, Patricia A; Ji, Bu-Tian; Bassig, Bryan; Lu, Wei; Xue, Shouzheng; Chow, Wong-Ho; Lan, Qing; Purdue, Mark P; Rothman, Nathaniel; Vermeulen, Roel</p> <p>2015-01-01</p> <p>Trichloroethylene (TCE) is a carcinogen that has been linked to kidney cancer and possibly other cancer sites including non-Hodgkin lymphoma. Its use in China has increased since the early 1990s with China's growing metal, electronic, and telecommunications industries. We examined historical occupational TCE <span class="hlt">air</span> <span class="hlt">concentration</span> patterns in a database of TCE inspection measurements collected in Shanghai, China to identify temporal trends and broad contrasts among occupations and industries. Using a database of 932 short-term, area TCE <span class="hlt">air</span> inspection measurements collected in Shanghai worksites from 1968 through 2000 (median year 1986), we developed mixed-effects models to evaluate job-, industry-, and time-specific TCE <span class="hlt">air</span> <span class="hlt">concentrations</span>. Models of TCE <span class="hlt">air</span> <span class="hlt">concentrations</span> from Shanghai work sites predicted that exposures decreased 5-10% per year between 1968 and 2000. Measurements collected near launderers and dry cleaners had the highest predicted geometric means (GM for 1986 = 150-190 mg m(-3)). The majority (53%) of the measurements were collected in metal treatment jobs. In a model restricted to measurements in metal treatment jobs, predicted GMs for 1986 varied 35-fold across industries, from 11 mg m(-3) in 'other metal products/repair' industries to 390 mg m(-3) in 'ships/aircrafts' industries. TCE workplace <span class="hlt">air</span> <span class="hlt">concentrations</span> appeared to have dropped over time in Shanghai, China between 1968 and 2000. Understanding differences in TCE <span class="hlt">concentrations</span> across time, occupations, and industries may assist future epidemiologic studies in China. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2014.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930092260','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930092260"><span>Some possibilities of using <span class="hlt">gas</span> mixtures other than <span class="hlt">air</span> in aerodynamic research</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chapman, Dean R</p> <p>1956-01-01</p> <p>A study is made of the advantages that can be realized in compressible-flow research by employing a substitute heavy <span class="hlt">gas</span> in place of <span class="hlt">air</span>. The present report is based on the idea that by properly mixing a heavy monatomic <span class="hlt">gas</span> with a suitable heavy polyatomic <span class="hlt">gas</span>, it is possible to obtain a heavy <span class="hlt">gas</span> mixture which has the correct ratio of specific heats and which is nontoxic, nonflammable, thermally stable, chemically inert, and comprised of commercially available components. Calculations were made of wind-tunnel characteristics for 63 <span class="hlt">gas</span> pairs comprising 21 different polyatomic gases properly mixed with each of three monatomic gases (argon, krypton, and zenon).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A31J..05Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A31J..05Q"><span><span class="hlt">Air</span> Quality, Human Health and Climate Implications of China's Synthetic Natural <span class="hlt">Gas</span> Development</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qin, Y.; Mauzerall, D. L.; Wagner, F.; Smith, K. R.; Peng, W.; Yang, J.; Zhu, T.</p> <p>2016-12-01</p> <p>Facing severe <span class="hlt">air</span> pollution and growing dependence on natural <span class="hlt">gas</span> imports, the Chinese government is planning an enormous increase in synthetic natural <span class="hlt">gas</span> (SNG) production. Although displacement of coal with SNG benefits <span class="hlt">air</span> quality, it increases carbon dioxide (CO2) emissions and thus worsens climate change. Primarily due to variation in <span class="hlt">air</span> pollutant and CO2 emission factors as well as energy efficiencies across sectors and regions, the replacement of coal with SNG results in varying degrees of <span class="hlt">air</span> quality and adverse climate impacts. Here we conduct an integrated assessment to estimate the <span class="hlt">air</span> quality, human health, and adverse climate impacts of various sectoral and regional SNG substitution strategies for coal in China in 2020. We find that using all planned production of SNG in the residential sector results in an annual decrease of approximately 43,000 (22,000 to 63,000) outdoor-<span class="hlt">air</span>-pollution-associated Chinese premature mortalities, with ranges determined by the low and high estimates of relative risks. If changes in indoor/household <span class="hlt">air</span> pollution were also included the decrease would be larger. By comparison, this is a 10 and 60 times greater reduction in premature mortalities than obtained when the SNG displaces coal in the industrial or power sectors, respectively. Deploying SNG as a coal replacement in the industrial or power sectors also has a 4-5 times higher carbon penalty than utilization in the residential sector due to inefficiencies in current household coal use. If carbon capture and storage (CCS) is used in SNG production, substituting SNG for coal can provide both <span class="hlt">air</span> quality and climate co-benefits in all scenarios. However, even with CCS, SNG emits 22-40% (depending on end-use) more CO2 than the same amount of conventional <span class="hlt">gas</span>. For existing SNG projects, we find displacing coal with SNG in the residential sector provides the largest <span class="hlt">air</span> quality and health benefits with the smallest carbon penalties of deployment in any sector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25345920','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25345920"><span>Influence of relative humidity on VOC <span class="hlt">concentrations</span> in indoor <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Markowicz, Pawel; Larsson, Lennart</p> <p>2015-04-01</p> <p>Volatile organic compounds (VOCs) may be emitted from surfaces indoors leading to compromised <span class="hlt">air</span> quality. This study scrutinized the influence of relative humidity (RH) on VOC <span class="hlt">concentrations</span> in a building that had been subjected to water damage. While <span class="hlt">air</span> samplings in a damp room at low RH (21-22%) only revealed minor amounts of 2-ethylhexanol (3 μg/m(3)) and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB, 8 μg/m(3)), measurements performed after a rapid increase of RH (to 58-75%) revealed an increase in VOC <span class="hlt">concentrations</span> which was 3-fold for 2-ethylhexanol and 2-fold for TXIB. Similar VOC emission patterns were found in laboratory analyses of moisture-affected and laboratory-contaminated building materials. This study demonstrates the importance of monitoring RH when sampling indoor <span class="hlt">air</span> for VOCs in order to avoid misleading conclusions from the analytical results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApPhB.123..149W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApPhB.123..149W"><span>Calibration-free wavelength modulation spectroscopy for <span class="hlt">gas</span> <span class="hlt">concentration</span> measurements using a quantum cascade laser</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wei, Min; Kan, RuiFeng; Chen, Bing; Xu, ZhenYu; Yang, ChenGuang; Chen, Xiang; Xia, HuiHui; Hu, Mai; He, Yabai; Liu, JianGuo; Fan, XueLi; Wang, Wei</p> <p>2017-05-01</p> <p>We report the development of an accurate calibration-free wavelength-scanned wavelength modulation spectroscopy system based on the temporal wavelength response of a current-modulated quantum cascade laser (QCL) for <span class="hlt">gas</span> <span class="hlt">concentration</span> detections. Accurate measurements and determination of the QCL output intensity and wavelength response to current modulation enabled calculations of 1f-normalized 2f signal to obtain spectroscopic information with and without <span class="hlt">gas</span> absorption in the beam path. The <span class="hlt">gas</span> <span class="hlt">concentration</span> was retrieved by fitting a simulation spectrum based on spectral line parameters to the background-subtracted 1f-normalized 2f signal based on measurements. In this paper, we demonstrate the performance of the developed system for the CH4 detection by applying an infrared QCL (at 7.84 µm or 1275 cm-1) to probe its two infrared transition lines at 1275.042 cm-1 and 1275.387 cm-1. The experimental results indicated very good agreements between measurements and modeling, for integrated absorbance ranging from 0.0057 cm-1 to 0.11 cm-1 (or absorbance ranging from 0.029 to 0.57). The extracted integrated absorbance was highly linear ( R = 0.99996) to the <span class="hlt">gas</span> sample <span class="hlt">concentration</span>. Deviations between the nominal sample <span class="hlt">gas</span> <span class="hlt">concentrations</span> and the extracted <span class="hlt">gas</span> <span class="hlt">concentrations</span> calculated based on HITRAN spectroscopic parameters were within 3.5%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-08-12/pdf/2011-20450.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-08-12/pdf/2011-20450.pdf"><span>76 FR 50164 - Protocol <span class="hlt">Gas</span> Verification Program and Minimum Competency Requirements for <span class="hlt">Air</span> Emission Testing...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2011-08-12</p> <p>...-AQ06 Protocol <span class="hlt">Gas</span> Verification Program and Minimum Competency Requirements for <span class="hlt">Air</span> Emission Testing... correct certain portions of the Protocol <span class="hlt">Gas</span> Verification Program and Minimum Competency Requirements for... final rule that amends the Agency's Protocol <span class="hlt">Gas</span> Verification Program (PGVP) and the minimum competency...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A31B2170W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A31B2170W"><span>The Impact of a Potential Shale <span class="hlt">Gas</span> Development in Germany and the United Kingdom on Local and Regional <span class="hlt">Air</span> Quality</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weger, L.; Lupascu, A.; Cremonese, L.; Butler, T. M.</p> <p>2017-12-01</p> <p>Numerous countries in Europe that possess domestic shale <span class="hlt">gas</span> reserves are considering exploiting this unconventional <span class="hlt">gas</span> resource as part of their energy transition agenda. While natural <span class="hlt">gas</span> generates less CO2 emissions upon combustion compared to coal or oil, making it attractive as a bridge in the transition from fossil fuels to renewables, production of shale <span class="hlt">gas</span> leads to emissions of CH4 and <span class="hlt">air</span> pollutants such as NOx, VOCs and PM. These gases in turn influence the climate as well as <span class="hlt">air</span> quality. In this study, we investigate the impact of a potential shale <span class="hlt">gas</span> development in Germany and the United Kingdom on local and regional <span class="hlt">air</span> quality. This work builds on our previous study in which we constructed emissions scenarios based on shale <span class="hlt">gas</span> utilization in these counties. In order to explore the influence of shale <span class="hlt">gas</span> production on <span class="hlt">air</span> quality, we investigate emissions predicted from our shale <span class="hlt">gas</span> scenarios with the Weather Research and Forecasting model with chemistry (WRF-Chem) model. In order to do this, we first design a model set-up over Europe and evaluate its performance for the meteorological and chemical parameters. Subsequently we add shale <span class="hlt">gas</span> emissions fluxes based on the scenarios over the area of the grid in which the shale <span class="hlt">gas</span> activities are predicted to occur. Finally, we model these emissions and analyze the impact on <span class="hlt">air</span> quality on both a local and regional scale. The aims of this work are to predict the range of adverse effects on <span class="hlt">air</span> quality, highlight the importance of emissions control strategies in reducing <span class="hlt">air</span> pollution, to promote further discussion, and to provide policy makers with information for decision making on a potential shale <span class="hlt">gas</span> development in the two study countries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25810398','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25810398"><span>Impact of natural <span class="hlt">gas</span> extraction on PAH levels in ambient <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Paulik, L Blair; Donald, Carey E; Smith, Brian W; Tidwell, Lane G; Hobbie, Kevin A; Kincl, Laurel; Haynes, Erin N; Anderson, Kim A</p> <p>2015-04-21</p> <p>Natural <span class="hlt">gas</span> extraction, often referred to as "fracking," has increased rapidly in the U.S. in recent years. To address potential health impacts, passive <span class="hlt">air</span> samplers were deployed in a rural community heavily affected by the natural <span class="hlt">gas</span> boom. Samplers were analyzed for 62 polycyclic aromatic hydrocarbons (PAHs). Results were grouped based on distance from each sampler to the nearest active well. PAH levels were highest when samplers were closest to active wells. Additionally, PAH levels closest to natural <span class="hlt">gas</span> activity were an order of magnitude higher than levels previously reported in rural areas. Sourcing ratios indicate that PAHs were predominantly petrogenic, suggesting that elevated PAH levels were influenced by direct releases from the earth. Quantitative human health risk assessment estimated the excess lifetime cancer risks associated with exposure to the measured PAHs. Closest to active wells, the risk estimated for maximum residential exposure was 2.9 in 10 000, which is above the U.S. EPA's acceptable risk level. Overall, risk estimates decreased 30% when comparing results from samplers closest to active wells to those farthest. This work suggests that natural <span class="hlt">gas</span> extraction may be contributing significantly to PAHs in <span class="hlt">air</span>, at levels that are relevant to human health.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27400263','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27400263"><span>Emissions of Polycyclic Aromatic Hydrocarbons from Natural <span class="hlt">Gas</span> Extraction into <span class="hlt">Air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Paulik, L Blair; Donald, Carey E; Smith, Brian W; Tidwell, Lane G; Hobbie, Kevin A; Kincl, Laurel; Haynes, Erin N; Anderson, Kim A</p> <p>2016-07-19</p> <p>Natural <span class="hlt">gas</span> extraction, often referred to as "fracking", has increased rapidly in the United States in recent years. To address potential health impacts, passive <span class="hlt">air</span> samplers were deployed in a rural community heavily affected by the natural <span class="hlt">gas</span> boom. Samplers were analyzed for 62 polycyclic aromatic hydrocarbons (PAHs). Results were grouped based on distance from each sampler to the nearest active well. Levels of benzo[a]pyrene, phenanthrene, and carcinogenic potency of PAH mixtures were highest when samplers were closest to active wells. PAH levels closest to natural <span class="hlt">gas</span> activity were comparable to levels previously reported in rural areas in winter. Sourcing ratios indicated that PAHs were predominantly petrogenic, suggesting that PAH levels were influenced by direct releases from the earth. Quantitative human health risk assessment estimated the excess lifetime cancer risks associated with exposure to the measured PAHs. At sites closest to active wells, the risk estimated for maximum residential exposure was 0.04 in a million, which is below the U.S. Environmental Protection Agency's acceptable risk level. Overall, risk estimates decreased 30% when comparing results from samplers closest to active wells to those farthest from them. This work suggests that natural <span class="hlt">gas</span> extraction is contributing PAHs to the <span class="hlt">air</span>, at levels that would not be expected to increase cancer risk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4415607','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4415607"><span>Impact of natural <span class="hlt">gas</span> extraction on Pah levels in ambient <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Paulik, L. Blair; Donald, Carey E.; Smith, Brian W.; Tidwell, Lane G.; Hobbie, Kevin A.; Kincl, Laurel; Haynes, Erin N.; Anderson, Kim A.</p> <p>2015-01-01</p> <p>Natural <span class="hlt">gas</span> extraction, often referred to as “fracking,” has increased rapidly in the U.S. in recent years. To address potential health impacts, passive <span class="hlt">air</span> samplers were deployed in a rural community heavily affected by the natural <span class="hlt">gas</span> boom. Samplers were analyzed for 62 polycyclic aromatic hydrocarbons (PAHs). Results were grouped based on distance from each sampler to the nearest active well. PAH levels were highest when samplers were closest to active wells. Additionally, PAH levels closest to natural <span class="hlt">gas</span> activity were an order of magnitude higher than levels previously reported in rural areas. Sourcing ratios indicate that PAHs were predominantly petrogenic, suggesting that elevated PAH levels were influenced by direct releases from the earth. Quantitative human health risk assessment estimated the excess lifetime cancer risks associated with exposure to the measured PAHs. Closest to active wells, the risk estimated for maximum residential exposure was 2.9 in 10,000, which is above the U.S. EPA's acceptable risk level. Overall, risk estimates decreased 30% when comparing results from samplers closest to active wells to those farthest. This work suggests that natural <span class="hlt">gas</span> extraction may be contributing significantly to PAHs in <span class="hlt">air</span>, at levels that are relevant to human health. PMID:25810398</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/868504','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/868504"><span>Cooler and particulate separator for an off-<span class="hlt">gas</span> stack</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Wright, George T.</p> <p>1992-01-01</p> <p>An off-<span class="hlt">gas</span> stack for a melter comprising an <span class="hlt">air</span> conduit leading to two sets of holes, one set injecting <span class="hlt">air</span> into the off-<span class="hlt">gas</span> stack near the melter plenum and the second set injecting <span class="hlt">air</span> downstream of the first set. The first set injects <span class="hlt">air</span> at a compound angle, having both downward and tangential components, to create a reverse vortex flow, counter to the direction of flow of <span class="hlt">gas</span> through the stack and also along the periphery of the stack interior surface. <span class="hlt">Air</span> from the first set of holes pervents recirculation zones from forming and the attendant accumulation of particulate deposits on the wall of the stack and will also return to the plenum any particulate swept up in the <span class="hlt">gas</span> entering the stack. The second set of holes injects <span class="hlt">air</span> in the same direction as the <span class="hlt">gas</span> in the stack to compensate for the pressure drop and to prevent the <span class="hlt">concentration</span> of condensate in the stack. A set of sprayers, receiving water from a second conduit, is located downstream of the second set of holes and sprays water into the <span class="hlt">gas</span> to further cool it.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/10138238','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/10138238"><span>Cooler and particulate separator for an off-<span class="hlt">gas</span> stack</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Wright, G.T.</p> <p>1991-04-08</p> <p>This report describes an off-<span class="hlt">gas</span> stack for a melter, furnace or reaction vessel comprising an <span class="hlt">air</span> conduit leading to two sets of holes, one set injecting <span class="hlt">air</span> into the off-<span class="hlt">gas</span> stack near the melter plenum and the second set injecting <span class="hlt">air</span> downstream of the first set. The first set injects <span class="hlt">air</span> at a compound angle, having both downward and tangential components, to create a reverse vortex flow, counter to the direction of flow of <span class="hlt">gas</span> through the stack and also along the periphery of the stack interior surface. <span class="hlt">Air</span> from the first set of holes prevents recirculation zones from forming and the attendant accumulation of particulate deposits on the wall of the stack and will also return to the plenum any particulate swept up in the <span class="hlt">gas</span> entering the stack. The second set of holes injects <span class="hlt">air</span> in the same direction as the <span class="hlt">gas</span> in the stack to compensate for the pressure drop and to prevent the <span class="hlt">concentration</span> of condensate in the stack. A set of sprayers, receiving water from a second conduit, is located downstream of the second set of holes and sprays water into the <span class="hlt">gas</span> to further cool it.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018EPJWC.17601019S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018EPJWC.17601019S"><span>Hydrogen <span class="hlt">gas</span> <span class="hlt">concentration</span> measurement in small area using raman lidar measurement technnology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sugimoto, Sachiyo; Asahi, Ippei; Shiina, Tatuso</p> <p>2018-04-01</p> <p>When change of hydrogen(H2) <span class="hlt">gas</span> <span class="hlt">concentration</span> in a certain point is measured, non-contact measurement technology with high temporal and spatial resolution is necessary. In this study, H2 <span class="hlt">concentration</span> in the small area of <1cm2 under the <span class="hlt">gas</span> flow was measured by using a Raman lidar. Raman scattering light at the measurement point of 750mm ahead was detected by the Raman lidar. As a result, it was proved that the H2 <span class="hlt">concentration</span> of more than 100ppm could be successfully measured.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.1674P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.1674P"><span>Effect of <span class="hlt">air</span> turbulence on <span class="hlt">gas</span> transport in soil; comparison of approaches</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pourbakhtiar, Alireza; Papadikis, Konstantinos; Poulsen, Tjalfe; Bridge, Jonathan; Wilkinson, Stephen</p> <p>2017-04-01</p> <p>Greenhouse gases are playing the key role in global warming. Soil is a source of greenhouse gases such as methane (CH4). Radon (Rn) which is a radioactive <span class="hlt">gas</span> can emit form subsurface into the atmosphere and leads to health concerns in urban areas. Temperature, humidity, <span class="hlt">air</span> pressure and vegetation of soil can affect <span class="hlt">gas</span> emissions inside soil (Oertel et al., 2016). It's shown in many cases that wind induced fluctuations is an important factor in transport of <span class="hlt">gas</span> through soil and other porous media. An example is: landfill <span class="hlt">gas</span> emissions (Poulsen et al., 2001). We applied an experimental equipment for measuring controlled <span class="hlt">air</span> turbulence on <span class="hlt">gas</span> transport in soil in relation to the depth of sample. Two approaches for measurement of effect of wind turbulence on <span class="hlt">gas</span> transport were applied and compared. Experiments were carried out with diffusion of CO2 and <span class="hlt">air</span> as tracer gases with average vertical wind speeds of 0 to 0.83 m s-1. In approach A, Six different sample thicknesses from 5 to 30 cm were selected and total of 4 different wind conditions with different speed and fluctuations were applied. In approach B, a sample with constant depth was used. Five oxygen sensors were places inside sample at different depths. Total of 111 experiments were carried out. <span class="hlt">Gas</span> transport is described by advection-dispersion equation. <span class="hlt">Gas</span> transport is quantified as a dispersion coefficient. Oxygen breakthrough curves as a function of distance to the surface of the sample exposed to wind were derived numerically with an explicit forward time, central space finite-difference based model to evaluate <span class="hlt">gas</span> transport. We showed that wind turbulence-induced fluctuations is an important factor in <span class="hlt">gas</span> transport that can increase <span class="hlt">gas</span> transport with average of 45 times more than molecular diffusion under zero wind condition. Comparison of two strategies for experiments, indicated that, constant deep samples (Approach B) are more reliable for measurement of <span class="hlt">gas</span> transport under influence of wind</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JGRB..11212306K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JGRB..11212306K"><span><span class="hlt">Gas</span> hydrate <span class="hlt">concentration</span> and characteristics within Hydrate Ridge inferred from multicomponent seismic reflection data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kumar, Dhananjay; Sen, Mrinal K.; Bangs, Nathan L.</p> <p>2007-12-01</p> <p>A seismic experiment composed of streamer and ocean bottom seismometer (OBS) surveys was conducted in the summer of 2002 at southern Hydrate Ridge, offshore Oregon, to map the <span class="hlt">gas</span> hydrate distribution within the hydrate stability zone. <span class="hlt">Gas</span> hydrate <span class="hlt">concentrations</span> within the reservoir can be estimated with P wave velocity (Vp); however, we can further constrain <span class="hlt">gas</span> hydrate <span class="hlt">concentrations</span> using S wave velocity (Vs), and use Vs through its relationship to Vp (Vp/Vs) to reveal additional details such as <span class="hlt">gas</span> hydrate form within the matrix (i.e., hydrate cements the grains, becomes part of the matrix frame or floats in pore space). Both Vp and Vs can be derived simultaneously by inverting multicomponent seismic data. In this study, we use OBS data to estimate seismic velocities where both <span class="hlt">gas</span> hydrate and free <span class="hlt">gas</span> are present in the shallow sediments. Once Vp and Vs are estimated, they are simultaneously matched with modeled velocities to estimate the <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span>. We model Vp using an equation based on a modification of Wood's equation that incorporates an appropriate rock physics model and Vs using an empirical relation. The <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span> is estimated to be up to 7% of the rock volume, or 12% of the pore space. However, Vp and Vs do not always fit the model simultaneously. Vp can vary substantially more than Vs. Thus we conclude that a model, in which higher <span class="hlt">concentrations</span> of hydrate do not affect shear stiffness, is more appropriate. Results suggest <span class="hlt">gas</span> hydrates form within the pore space of the sediments and become part of the rock framework in our survey area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/874694','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/874694"><span>Compressor discharge bleed <span class="hlt">air</span> circuit in <span class="hlt">gas</span> turbine plants and related method</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Anand, Ashok Kumar; Berrahou, Philip Fadhel; Jandrisevits, Michael</p> <p>2002-01-01</p> <p>A <span class="hlt">gas</span> turbine system that includes a compressor, a turbine component and a load, wherein fuel and compressor discharge bleed <span class="hlt">air</span> are supplied to a combustor and gaseous products of combustion are introduced into the turbine component and subsequently exhausted to atmosphere. A compressor discharge bleed <span class="hlt">air</span> circuit removes bleed <span class="hlt">air</span> from the compressor and supplies one portion of the bleed <span class="hlt">air</span> to the combustor and another portion of the compressor discharge bleed <span class="hlt">air</span> to an exhaust stack of the turbine component in a single cycle system, or to a heat recovery steam generator in a combined cycle system. In both systems, the bleed <span class="hlt">air</span> diverted from the combustor may be expanded in an <span class="hlt">air</span> expander to reduce pressure upstream of the exhaust stack or heat recovery steam generator.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/921792','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/921792"><span>Compressor discharge bleed <span class="hlt">air</span> circuit in <span class="hlt">gas</span> turbine plants and related method</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Anand, Ashok Kumar [Niskayuna, NY; Berrahou, Philip Fadhel [Latham, NY; Jandrisevits, Michael [Clifton Park, NY</p> <p>2003-04-08</p> <p>A <span class="hlt">gas</span> turbine system that includes a compressor, a turbine component and a load, wherein fuel and compressor discharge bleed <span class="hlt">air</span> are supplied to a combustor and gaseous products of combustion are introduced into the turbine component and subsequently exhausted to atmosphere. A compressor discharge bleed <span class="hlt">air</span> circuit removes bleed <span class="hlt">air</span> from the compressor and supplies one portion of the bleed <span class="hlt">air</span> to the combustor and another portion of the compressor discharge bleed <span class="hlt">air</span> to an exhaust stack of the turbine component in a single cycle system, or to a heat recovery steam generator in a combined cycle system. In both systems, the bleed <span class="hlt">air</span> diverted from the combustor may be expanded in an <span class="hlt">air</span> expander to reduce pressure upstream of the exhaust stack or heat recovery steam generator.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=317559&Lab=NERL&keyword=gas+AND+natural&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=317559&Lab=NERL&keyword=gas+AND+natural&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>Predicting <span class="hlt">Air</span> Quality Impacts Associated with Oil and <span class="hlt">Gas</span> Development in the Uinta Basin Using EPA’s Photochemical <span class="hlt">Air</span> Quality Model</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Rural areas with close proximity to oil and natural <span class="hlt">gas</span> operations in Utah have experienced winter ozone levels that exceed EPA’s National Ambient <span class="hlt">Air</span> Quality Standards (NAAQS). Through a collaborative effort, EPA Region 8 – <span class="hlt">Air</span> Program, ORD, and OAQPS used the Commun...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992teci.rept.....M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992teci.rept.....M"><span>Variable speed <span class="hlt">gas</span> engine-driven <span class="hlt">air</span> compressor system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morgan, J. R.; Ruggles, A. E.; Chen, T. N.; Gehret, J.</p> <p>1992-11-01</p> <p>Tecogen Inc. and Ingersoll-Rand Co. as a subcontractor have designed a nominal 150-hp <span class="hlt">gas</span> engine-driven <span class="hlt">air</span> compressor utilizing the TECODRIVE 8000 engine and the Ingersoll-Rand 178.5-mm twin screw compressor. Phase 1 included the system engineering and design, economic and applications studies, and a draft commercialization plan. Phase 2 included controls development, laboratory prototype construction, and performance testing. The testing conducted verified that the compressor meets all design specifications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10970675','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10970675"><span>Turbulence and wave breaking effects on <span class="hlt">air</span>-water <span class="hlt">gas</span> exchange</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Boettcher; Fineberg; Lathrop</p> <p>2000-08-28</p> <p>We present an experimental characterization of the effects of turbulence and breaking gravity waves on <span class="hlt">air</span>-water <span class="hlt">gas</span> exchange in standing waves. We identify two regimes that govern aeration rates: turbulent transport when no wave breaking occurs and bubble dominated transport when wave breaking occurs. In both regimes, we correlate the qualitative changes in the aeration rate with corresponding changes in the wave dynamics. In the latter regime, the strongly enhanced aeration rate is correlated with measured acoustic emissions, indicating that bubble creation and dynamics dominate <span class="hlt">air</span>-water exchange.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940019862','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940019862"><span>Ethylene Trace-<span class="hlt">gas</span> Techniques for High-speed Flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Davis, David O.; Reichert, Bruce A.</p> <p>1994-01-01</p> <p>Three applications of the ethylene trace-<span class="hlt">gas</span> technique to high-speed flows are described: flow-field tracking, <span class="hlt">air-to-air</span> mixing, and bleed mass-flow measurement. The technique involves injecting a non-reacting <span class="hlt">gas</span> (ethylene) into the flow field and measuring the <span class="hlt">concentration</span> distribution in a downstream plane. From the distributions, information about flow development, mixing, and mass-flow rates can be dtermined. The trace-<span class="hlt">gas</span> apparatus and special considerations for use in high-speed flow are discussed. A description of each application, including uncertainty estimates is followed by a demonstrative example.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ThEng..63...24K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ThEng..63...24K"><span>Calculation of <span class="hlt">gas</span> temperature at the outlet of the combustion chamber and in the <span class="hlt">air-gas</span> channel of a <span class="hlt">gas</span>-turbine unit by data of acceptance tests in accordance with ISO</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kostyuk, A. G.; Karpunin, A. P.</p> <p>2016-01-01</p> <p>This article describes a high accuracy method enabling performance of the calculation of real values of the initial temperature of a <span class="hlt">gas</span> turbine unit (GTU), i.e., the <span class="hlt">gas</span> temperature at the outlet of the combustion chamber, in a situation where manufacturers do not disclose this information. The features of the definition of the initial temperature of the GTU according to ISO standards were analyzed. It is noted that the true temperatures for high-temperature GTUs is significantly higher than values determined according to ISO standards. A computational procedure for the determination of <span class="hlt">gas</span> temperatures in the <span class="hlt">air-gas</span> channel of the <span class="hlt">gas</span> turbine and cooling <span class="hlt">air</span> consumptions over blade rims is proposed. As starting equations, the heat balance equation and the flow mixing equation for the combustion chamber are assumed. Results of acceptance GTU tests according to ISO standards and statistical dependencies of required cooling <span class="hlt">air</span> consumptions on the <span class="hlt">gas</span> temperature and the blade metal are also used for calculations. An example of the calculation is given for one of the units. Using a developed computer program, the temperatures in the <span class="hlt">air-gas</span> channel of certain GTUs are calculated, taking into account their design features. These calculations are performed on the previously published procedure for the detailed calculation of the cooled <span class="hlt">gas</span> turbine subject to additional losses arising because of the presence of the cooling system. The accuracy of calculations by the computer program is confirmed by conducting verification calculations for the GTU of the Mitsubishi Comp. and comparing results with published data of the company. Calculation data for temperatures were compared with the experimental data and the characteristics of the GTU, and the error of the proposed method is estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15488935','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15488935"><span>Effect of <span class="hlt">gas</span> velocity and influent <span class="hlt">concentration</span> on biofiltration of gasoline off-<span class="hlt">gas</span> from soil vapor extraction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Namkoong, Wan; Park, Joon-Seok; VanderGheynst, Jean S</p> <p>2004-11-01</p> <p>This study was conducted to evaluate the effects of <span class="hlt">gas</span> inlet <span class="hlt">concentration</span> and velocity on the biofiltration of gasoline vapor. Gasoline vapor was treated using a compost biofilter operated in an upflow mode for about 3 months. The inlet <span class="hlt">concentration</span> of gasoline total petroleum hydrocarbon (TPH) ranged from about 300 to 7000 mgm(-3) and <span class="hlt">gas</span> was injected at velocities of 6 and 15 mh(-1) (empty bed residence time (EBRT)=10 and 4 min, respectively). The maximum elimination capacities of TPH at 6 and 15 mh(-1) found in this research were over 24 and 19 gm(-3) of filling material h(-1), respectively. TPH removal data was fit using a first-order kinetic relationship. In the low <span class="hlt">concentration</span> range of 300-3000 mg m(-3), the first-order kinetic constants varied between about 0.10 and 0.29 min(-1) regardless of <span class="hlt">gas</span> velocities. At TPH <span class="hlt">concentrations</span> greater than 3000 mgm(-3), the first-order kinetic constants were about 0.09 and 0.07 min(-1) at <span class="hlt">gas</span> velocities of 6 mh(-1) and 15 mh(-1), respectively. To evaluate microbial dynamics, dehydrogenase activity, CO2 generation and microbial species diversity were analyzed. Dehydrogenase activity could be used as an indicator of microbial activity. TPH removal corresponded well with CO2 evolution. The average CO2 recovery efficiency for the entire biofilter ranged between 60% and 70%. When the <span class="hlt">gas</span> velocity was 6 mh(-1), most of the microbial activity and TPH removal occurred in the first quarter of the biofilter. However, when the <span class="hlt">gas</span> velocity was 15 mh(-1), the entire column contributed to removal. Spatial and temporal variations in the biofilter microbial population were also observed. Nearly 60% of the colonies isolated from the compost media prior to biofiltration were Bacillus. After 90 days of biofiltration, the predominant species in the lower portion (0-50 cm) of the filter were Rhodococcus, while Pseudomonas and Acinetobacter dominated the upper portion (75-100 cm). copyright 2004 Elsevier Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=160803&keyword=humans+AND+cause+AND+pollution&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=160803&keyword=humans+AND+cause+AND+pollution&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>LARGE-SCALE PREDICTIONS OF MOBILE SOURCE CONTRIBUTIONS TO <span class="hlt">CONCENTRATIONS</span> OF TOXIC <span class="hlt">AIR</span> POLLUTANTS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>This presentation shows <span class="hlt">concentrations</span> and deposition of toxic <span class="hlt">air</span> pollutants predicted by a 3-D <span class="hlt">air</span> quality model, the Community Multi Scale <span class="hlt">Air</span> Quality (CMAQ) modeling system. Contributions from both on-road and non-road mobile sources are analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712332B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712332B"><span>Ambient <span class="hlt">air</span>/near-field measurements of methane and Volatile Organic Compounds (VOCs) from a natural <span class="hlt">gas</span> facility in Northern Europe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baudic, Alexia; Gros, Valérie; Bonsang, Bernard; Baisnee, Dominique; Vogel, Félix; Yver Kwok, Camille; Ars, Sébastien; Finlayson, Andrew; Innocenti, Fabrizio; Robinson, Rod</p> <p>2015-04-01</p> <p>Since the 1970's, the natural <span class="hlt">gas</span> consumption saw a rapid growth in large urban centers, thus becoming an important energy resource to meet continuous needs of factories and inhabitants. Nevertheless, it can be a substantial source of methane (CH4) and pollutants in urban areas. For instance, we have determined that about 20% of Volatile Organic Compounds (VOCs) in downtown Paris are originating from this emission source (Baudic, Gros et al., in preparation). Within the framework of the "Fugitive Methane Emissions" (FuME) project (Climate-KIC, EIT); 2-weeks <span class="hlt">gas</span> measurements were conducted at a <span class="hlt">gas</span> compressor station in Northern Europe. Continuous ambient <span class="hlt">air</span> measurements of methane and VOCs <span class="hlt">concentrations</span> were performed using a cavity ring-down spectrometer (model G2201, Picarro Inc., Santa Clara, USA) and two portable GC-FID (Chromatotec, Saint-Antoine, France), respectively. On-site near-field samplings were also carried out at the source of two pipelines using stainless steel flasks (later analyzed with a laboratory GC-FID). The objective of this study aims to use VOCs as additional tracers in order to better characterize the fugitive methane emissions in a complex environment, which can be affected by several urban sources (road-traffic, others industries, etc.). Moreover, these measurements have allowed determining the chemical composition of this specific source. Our results revealed that the variability of methane and some VOCs was (rather) well correlated, especially for alkanes (ethane, propane, etc.). An analysis of selected events with strong <span class="hlt">concentrations</span> enhancement was performed using ambient <span class="hlt">air</span> measurements; thus allowing the preliminary identification of different emission sources. In addition, some flasks were also sampled in Paris to determine the local natural <span class="hlt">gas</span> composition. A comparison between both was then performed. Preliminary results from these experiments will be presented here.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19660000370','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19660000370"><span>Brazing retort manifold design concept may minimize <span class="hlt">air</span> contamination and enhance uniform <span class="hlt">gas</span> flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ruppe, E. P.</p> <p>1966-01-01</p> <p>Brazing retort manifold minimizes <span class="hlt">air</span> contamination, prevents <span class="hlt">gas</span> entrapment during purging, and provides uniform <span class="hlt">gas</span> flow into the retort bell. The manifold is easily cleaned and turbulence within the bell is minimized because all manifold construction lies outside the main enclosure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=gas+AND+liquid&id=EJ1037349','ERIC'); return false;" href="https://eric.ed.gov/?q=gas+AND+liquid&id=EJ1037349"><span>A "Greenhouse <span class="hlt">Gas</span>" Experiment for the Undergraduate Laboratory</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Gomez, Elaine; Paul, Melissa; Como, Charles; Barat, Robert</p> <p>2014-01-01</p> <p>This experiment and analysis offer an effective experience in greenhouse <span class="hlt">gas</span> reduction. Ammoniated water is flowed counter-current to a simulated flue <span class="hlt">gas</span> of <span class="hlt">air</span> and CO2 in a packed column. The gaseous CO2 <span class="hlt">concentrations</span> are measured with an on-line, non- dispersive, infrared analyzer. Column operating parameters include total <span class="hlt">gas</span> flux, dissolved…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860006746','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860006746"><span>Optical and probe determination of soot <span class="hlt">concentrations</span> in a model <span class="hlt">gas</span> turbine combustor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eckerle, W. A.; Rosfjord, T. J.</p> <p>1986-01-01</p> <p>An experimental program was conducted to track the variation in soot loading in a generic <span class="hlt">gas</span> turbine combustor. The burner is a 12.7-cm dia cylindrical device consisting of six sheet-metal louvers. Determination of soot loading along the burner length is achieved by measurement at the exit of the combustor and then at upstream stations by sequential removal of liner louvers to shorten burner length. Alteration of the flow field approaching and within the shortened burners is minimized by bypassing flow in order to maintain a constant linear pressure drop. The burner exhaust flow is sampled at the burner centerline to determine soot mass <span class="hlt">concentration</span> and smoke number. Characteristic particle size and number density, transmissivity of the exhaust flow, and local radiation from luminous soot particles in the exhaust are determined by optical techniques. Four test fuels are burned at three fuel-<span class="hlt">air</span> ratios to determine fuel chemical property and flow temperature influences. Particulate <span class="hlt">concentration</span> data indicate a strong oxidation mechanism in the combustor secondary zone, though the oxidation is significantly affected by flow temperature. Soot production is directly related to fuel smoke point.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28719193','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28719193"><span>Relationships between Atmospheric Transport Regimes and PCB <span class="hlt">Concentrations</span> in the <span class="hlt">Air</span> at Zeppelin, Spitsbergen.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ubl, Sandy; Scheringer, Martin; Hungerbühler, Konrad</p> <p>2017-09-05</p> <p>Polychlorinated biphenyls (PCBs) are persistent hazardous chemicals that are still detected in the atmosphere and other environmental media, although their production has been banned for several decades. At the long-term monitoring site, Zeppelin at Spitsbergen, different PCB congeners have been continuously measured for more than a decade. However, it is not clear what factors determine the seasonal and interannual variability of different (lighter versus heavier) PCB congeners. To investigate the influence of atmospheric transport patterns on PCB-28 and PCB-101 <span class="hlt">concentrations</span> at Zeppelin, we applied the Lagrangian Particle Dispersion Model FLEXPART and calculated "footprints" that indicate the potential source regions of <span class="hlt">air</span> arriving at Zeppelin. By means of a cluster analysis, we assigned groups of similar footprints to different transport regimes and analyzed the PCB <span class="hlt">concentrations</span> according to the transport regimes. The <span class="hlt">concentrations</span> of both PCB congeners are affected by the different transport regimes. For PCB-101, the origin of <span class="hlt">air</span> masses from the European continent is primarily related to high <span class="hlt">concentrations</span>; elevated PCB-101 <span class="hlt">concentrations</span> in winter can be explained by the high frequency of this transport regime in winter, whereas PCB-101 <span class="hlt">concentrations</span> are low when <span class="hlt">air</span> is arriving from the oceans. For PCB-28, in contrast, <span class="hlt">concentrations</span> are high during summer when <span class="hlt">air</span> is mainly arriving from the oceans but low when <span class="hlt">air</span> is arriving from the continents. The most likely explanation of this finding is that local emissions of PCB-28 mask the effect of long-range transport and determine the <span class="hlt">concentrations</span> measured at Zeppelin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24856640','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24856640"><span>Exposure of unsuspecting workers to deadly atmospheres in below-ground confined spaces and investigation of related whole-<span class="hlt">air</span> sample composition using adsorption <span class="hlt">gas</span> chromatography.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smith, Philip A; Lockhart, Bonnie; Besser, Brett W; Michalski, Michael A R</p> <p>2014-01-01</p> <p>Hazardous atmospheres in confined spaces may be obvious when a source of <span class="hlt">air</span> contamination or oxygen (O2) deficiency is recognized. Such is often the case in general industry settings, especially with work processes which create hazardous atmospheres that may be anticipated. Hazards present in active sewers are also well recognized; but the possibility that O2 deficiency or high airborne contaminant <span class="hlt">concentrations</span> may exist in new construction sewers or storm drains has been repeatedly ignored with deadly results. Low O2 and high carbon dioxide (CO2) <span class="hlt">concentrations</span> may exist in new construction manholes that have not yet been connected to an active sewer or drain system, and these <span class="hlt">concentrations</span> have been shown to vary over time. A recent incident is described where workers repeatedly entered such a confined space without incident, but subsequent entry resulted in a fatality and a near-miss for a co-worker rescuer. Additional cases are discussed, with an emphasis placed on elevated CO2 <span class="hlt">concentrations</span> as a causative factor. A description is provided for the adsorptive <span class="hlt">gas</span> chromatography whole-<span class="hlt">air</span> analysis methodology used to quantitatively determine atmospheric conditions present at this type of fatality site or others after an incident, and for the <span class="hlt">gas</span> chromatography-mass spectrometry method used to provide confirmation of analyte identity with high certainty. Many types of confined spaces may be encountered in addition to the underground varieties discussed, and many possible atmospheric hazards are possible. The definitive whole-<span class="hlt">air</span> analysis approach described here may be of use and should be considered to investigate many confined space fatality and near-miss cases, and to better understand the causes of dangerous atmosphere conditions that may arise in confined spaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70017596','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70017596"><span>Seasonal variability of soil-<span class="hlt">gas</span> radon <span class="hlt">concentration</span> in central California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>King, C.-Y.; Minissale, A.</p> <p>1994-01-01</p> <p>Radon <span class="hlt">concentrations</span> in soil <span class="hlt">gas</span> were measured by the track-etch method in 60 shallow holes, each 70 cm deep and supported by a capped plastic tube, along several major faults in central California during 1975-1985. This set of data was analyzed to investigate the seasonal variability of soil-<span class="hlt">gas</span> radon <span class="hlt">concentration</span> in an area which has various geological conditions but similar climate. The results show several different patterns of seasonal variations, but all of which can be largely attributed to the water-saturation and moisture-retention characteristics of the shallow part of the soil. During the rainy winter and spring seasons, radon tended to be confined underground by the water-saturated surface soil which had much reduced <span class="hlt">gas</span> permeability, while during the sunny summer and autumn seasons, it exhaled more readily as the soil became drier and more permeable. At several sites located on creeping faults, the radon-variation patterns changed with time, possibly because of disturbance of site condition by fault movement. ?? 1994.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=90035&keyword=CAPS&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=90035&keyword=CAPS&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span><span class="hlt">CONCENTRATED</span> AMBIENT <span class="hlt">AIR</span> PARTICLES INDUCE PULMONARY INFLAMMATION IN HEALTHY HUMAN VOLUNTEERS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p><br>We tested the hypothesis that exposure of healthy volunteers to <span class="hlt">concentrated</span> ambient particles (CAPS) is associated with an influx of inflammatory cells into the lower respiratory tract. Thirty-eight volunteers were exposed to either filtered <span class="hlt">air</span> or particles <span class="hlt">concentrated</span> fro...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21216057','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21216057"><span>A passive <span class="hlt">air</span> sampler for characterizing the vertical <span class="hlt">concentration</span> profile of gaseous phase polycyclic aromatic hydrocarbons in near soil surface <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yuzhong; Deng, Shuxing; Liu, Yanan; Shen, Guofeng; Li, Xiqing; Cao, Jun; Wang, Xilong; Reid, Brian; Tao, Shu</p> <p>2011-03-01</p> <p><span class="hlt">Air</span>-soil exchange is an important process governing the fate of polycyclic aromatic hydrocarbons (PAHs). A novel passive <span class="hlt">air</span> sampler was designed and tested for measuring the vertical <span class="hlt">concentration</span> profile of 4 low molecular weight PAHs in gaseous phase (PAH(LMW4)) in near soil surface <span class="hlt">air</span>. <span class="hlt">Air</span> at various heights from 5 to 520 mm above the ground was sampled by polyurethane foam disks held in down-faced cartridges. The samplers were tested at three sites: A: an extremely contaminated site, B: a site near A, and C: a background site on a university campus. Vertical <span class="hlt">concentration</span> gradients were revealed for PAH(LMW4) within a thin layer close to soil surface at the three sites. PAH <span class="hlt">concentrations</span> either decreased (Site A) or increased (Sites B and C) with height, suggesting either deposition to or evaporation from soils. The sampler is a useful tool for investigating <span class="hlt">air</span>-soil exchange of gaseous phase semi-volatile organic chemicals. Copyright © 2010 Elsevier Ltd. All rights reserved.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70195393','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70195393"><span>On factors influencing <span class="hlt">air</span>-water <span class="hlt">gas</span> exchange in emergent wetlands</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ho, David T.; Engel, Victor C.; Ferron, Sara; Hickman, Benjamin; Choi, Jay; Harvey, Judson W.</p> <p>2018-01-01</p> <p>Knowledge of <span class="hlt">gas</span> exchange in wetlands is important in order to determine fluxes of climatically and biogeochemically important trace gases and to conduct mass balances for metabolism studies. Very few studies have been conducted to quantify <span class="hlt">gas</span> transfer velocities in wetlands, and many wind speed/<span class="hlt">gas</span> exchange parameterizations used in oceanographic or limnological settings are inappropriate under conditions found in wetlands. Here six measurements of <span class="hlt">gas</span> transfer velocities are made with SF6 tracer release experiments in three different years in the Everglades, a subtropical peatland with surface water flowing through emergent vegetation. The experiments were conducted under different flow conditions and with different amounts of emergent vegetation to determine the influence of wind, rain, water flow, waterside thermal convection, and vegetation on <span class="hlt">air</span>-water <span class="hlt">gas</span> exchange in wetlands. Measured <span class="hlt">gas</span> transfer velocities under the different conditions ranged from 1.1 cm h−1 during baseline conditions to 3.2 cm h−1 when rain and water flow rates were high. Commonly used wind speed/<span class="hlt">gas</span> exchange relationships would overestimate the <span class="hlt">gas</span> transfer velocity by a factor of 1.2 to 6.8. <span class="hlt">Gas</span> exchange due to thermal convection was relatively constant and accounted for 14 to 51% of the total measured <span class="hlt">gas</span> exchange. Differences in rain and water flow among the different years were responsible for the variability in <span class="hlt">gas</span> exchange, with flow accounting for 37 to 77% of the <span class="hlt">gas</span> exchange, and rain responsible for up to 40%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19..777J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19..777J"><span>Modeling soil <span class="hlt">gas</span> dynamics in the context of noble <span class="hlt">gas</span> tracer applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jenner, Florian; Mayer, Simon; Aeschbach, Werner; Peregovich, Bernhard; Machado, Carlos</p> <p>2017-04-01</p> <p>Noble <span class="hlt">gas</span> tracer applications show a particular relevance for the investigation of <span class="hlt">gas</span> dynamics in the unsaturated zone, but also for a treatment of soil contamination as well as concerning exchange processes between soil and atmosphere. In this context, reliable conclusions require a profound understanding of underlying biogeochemical processes. With regard to noble <span class="hlt">gas</span> tracer applications, the dynamics of reactive and inert gases in the unsaturated zone is investigated. Based on long-term trends and varying climatic conditions, this is the first study providing general insights concerning the role of unsaturated zone processes. Modeling approaches are applied, in combination with an extensive set of measured soil <span class="hlt">air</span> composition data from appropriate sampling sites. On the one hand, a simple modeling approach allows to identify processes which predominantly determine inert <span class="hlt">gas</span> mixing ratios in soil <span class="hlt">air</span>. On the other hand, the well-proven and sophisticated modeling routine Min3P is applied to describe the measured data by accounting for the complex nature of subsurface <span class="hlt">gas</span> dynamics. Both measured data and model outcomes indicate a significant deviation of noble <span class="hlt">gas</span> mixing ratios in soil <span class="hlt">air</span> from the respective atmospheric values, occurring on seasonal scale. Observed enhancements of noble <span class="hlt">gas</span> mixing ratios are mainly caused by an advective balancing of depleted sum values of O2+CO2, resulting from microbial oxygen depletion in combination with a preferential dissolution of CO2. A contrary effect, meaning an enhanced sum value of O2+CO2, is shown to be induced at very dry conditions due to the different diffusivities of O2 and CO2. Soil <span class="hlt">air</span> composition data show a yearlong mass-dependent fractionation, occurring as a relative enhancement of heavier <span class="hlt">gas</span> species with respect to lighter ones. The diffusive balancing of <span class="hlt">concentration</span> gradients between soil <span class="hlt">air</span> and atmosphere is faster for lighter <span class="hlt">gas</span> species compared to heavier ones. The rather uniform fractionation is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25122950','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25122950"><span>Investigation of time-resolved atmospheric conditions and indoor/outdoor particulate matter <span class="hlt">concentrations</span> in homes with <span class="hlt">gas</span> and biomass cook stoves in Nogales, Sonora, Mexico.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Holmes, Heather A; Pardyjak, Eric R</p> <p>2014-07-01</p> <p>This paper reports findings from a case study designed to investigate indoor and outdoor <span class="hlt">air</span> quality in homes near the United States-Mexico border During the field study, size-resolved continuous particulate matter (PM) <span class="hlt">concentrations</span> were measured in six homes, while outdoor PM was simultaneously monitored at the same location in Nogales, Sonora, Mexico, during March 14-30, 2009. The purpose of the experiment was to compare PM in homes using different fuels for cooking, <span class="hlt">gas</span> versus biomass, and to obtain a spatial distribution of outdoor PM in a region where local sources vary significantly (e.g., highway, border crossing, unpaved roads, industry). Continuous PM data were collected every 6 seconds using a valve switching system to sample indoor and outdoor <span class="hlt">air</span> at each home location. This paper presents the indoor PM data from each home, including the relationship between indoor and outdoor PM. The meteorological conditions associated with elevated ambient PM events in the region are also discussed. Results indicate that indoor <span class="hlt">air</span> pollution has a strong dependence on cooking fuel, with <span class="hlt">gas</span> stoves having hourly averaged median PM3 <span class="hlt">concentrations</span> in the range of 134 to 157 microg m(-3) and biomass stoves 163 to 504 microg m(-1). Outdoor PM also indicates a large spatial heterogeneity due to the presence of microscale sources and meteorological influences (median PM3: 130 to 770 microg m(-3)). The former is evident in the median and range of daytime PM values (median PM3: 250 microg m(-3), maximum: 9411 microg m(-3)), while the meteorological influences appear to be dominant during nighttime periods (median PM3: 251 microg m(-3), maximum: 10,846 microg m(-3)). The atmospheric stability is quantified for three nighttime temperature inversion episodes, which were associated with an order of magnitude increase in PM10 at the regulatory monitor in Nogales, AZ (maximum increase: 12 to 474 microg m(-3)). Implications: Regulatory <span class="hlt">air</span> quality standards are based on outdoor</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27228750','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27228750"><span>[Raman Characterization of Hydrate Crystal Structure Influenced by Mine <span class="hlt">Gas</span> <span class="hlt">Concentration</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Bao-yong; Zhou, Hong-ji; Wu, Qiang; Gao, Xia</p> <p>2016-01-01</p> <p>CH4 /C2H6/N2 mixed hydrate formation experiments were performed at 2 degrees C and 5 MPa for three different mine <span class="hlt">gas</span> <span class="hlt">concentrations</span> (CH4/C2H6/N2, G1 = 54 : 36 : 10, G2 = 67.5 : 22.5 : 10, G3 = 81 : 9 : 10). Raman spectra for hydration products were obtained by using Microscopic Raman Spectrometer. Hydrate structure is determined by the Raman shift of symmetric C-C stretching vibration mode of C2H6 in the hydrate phase. This work is focused on the cage occupancies and hydration numbers, calculated by the fitting methods of Raman peaks. The results show that structure I (s I) hydrate forms in the G1 and G2 <span class="hlt">gas</span> systems, while structure II (s II) hydrate forms in the G3 <span class="hlt">gas</span> system, <span class="hlt">concentration</span> variation of C2H6 in the <span class="hlt">gas</span> samples leads to a change in hydrate structure from s I to s II; the percentages of CH4 and C2H6 in s I hydrate phase are less affected by the <span class="hlt">concentration</span> of <span class="hlt">gas</span> samples, the percentages of CH4 are respectively 34.4% and 35.7%, C2H6 are respectively 64.6% and 63.9% for <span class="hlt">gas</span> systems of G1 and G2, the percentages of CH4 and 2 H6 are respectively 73.5% and 22.8% for <span class="hlt">gas</span> systems of G3, the proportions of object molecules largely depend on the hydrate structure; CH4 and C2H6 molecules occupy 98%, 98% and 92% of the large cages and CH4 molecules occupy 80%, 60% and 84% of the small cages for <span class="hlt">gas</span> systems of G1, G2 and G3, respectively; additionally, N2 molecules occupy less than 5% of the small cages is due to its weak adsorption ability and the lower partial pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMED13B0888G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMED13B0888G"><span>The <span class="hlt">AirWaterGas</span> Teacher Professional Development Program: Lessons Learned by Pairing Scientists and Teachers to Develop Curriculum on Global Climate Change and Regional Unconventional Oil and <span class="hlt">Gas</span> Development</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gardiner, L. S.; Hatheway, B.; Rogers, J. D.; Casey, J. G.; Lackey, G.; Birdsell, D.; Brown, K.; Polmear, M.; Capps, S.; Rosenblum, J.; Sitterley, K.; Hafich, K. A.; Hannigan, M.; Knight, D.</p> <p>2015-12-01</p> <p>The <span class="hlt">AirWaterGas</span> Teacher Professional Development Program, run by the UCAR Center for Science Education, brought together scientists and secondary science teachers in a yearlong program culminating in the development of curriculum related to the impacts of unconventional oil and <span class="hlt">gas</span> development. Graduate students and research scientists taught about their research area and its relationship to oil and <span class="hlt">gas</span> throughout three online courses during the 2015-16 school year, during which teachers and scientists engaged in active online discussions. Topics covered included climate change, oil and <span class="hlt">gas</span> infrastructure, <span class="hlt">air</span> quality, water quality, public health, and practices and policies relating to oil and <span class="hlt">gas</span> development. Building upon their initial online interactions and a face-to-face meeting in March, teachers were paired with appropriate <span class="hlt">AirWaterGas</span> team members as science advisors during a month-long residency in Boulder, Colorado. During the residency, graduate student scientists provided resources and feedback as teachers developed curriculum projects in collaboration with each other and UCAR science educators. Additionally, teachers and <span class="hlt">AirWaterGas</span> researchers shared experiences on an oil and <span class="hlt">gas</span> well site tour, and a short course on drilling methods with a drilling rig simulator. Here, we share lessons learned from both sides of the aisle, including initial results from program assessment conducted with the participating teachers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A33C0233S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A33C0233S"><span>Creating a Methodology for Coordinating High-resolution <span class="hlt">Air</span> Quality Improvement Map and Greenhouse <span class="hlt">Gas</span> Mitigation Strategies in Pittsburgh City</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shi, J.; Donahue, N. M.; Klima, K.; Blackhurst, M.</p> <p>2016-12-01</p> <p>In order to tradeoff global impacts of greenhouse gases with highly local impacts of conventional <span class="hlt">air</span> pollution, researchers require a method to compare global and regional impacts. Unfortunately, we are not aware of a method that allows these to be compared, "apples-to-apples". In this research we propose a three-step model to compare possible city-wide actions to reduce greenhouse gases and conventional <span class="hlt">air</span> pollutants. We focus on Pittsburgh, PA, a city with consistently poor <span class="hlt">air</span> quality that is interested in reducing both greenhouse gases and conventional <span class="hlt">air</span> pollutants. First, we use the 2013 Pittsburgh Greenhouse <span class="hlt">Gas</span> Inventory to update the Blackhurst et al. model and conduct a greenhouse <span class="hlt">gas</span> abatement potentials and implementation costs of proposed greenhouse <span class="hlt">gas</span> reduction efforts. Second, we use field tests for PM2.5, NOx, SOx, organic carbon (OC) and elemental carbon (EC) data to inform a Land-use Regression Model for local <span class="hlt">air</span> pollution at a 100m x 100m spatial level, which combined with a social cost of <span class="hlt">air</span> pollution model (EASIUR) allows us to calculate economic social damages. Third, we combine these two models into a three-dimensional greenhouse <span class="hlt">gas</span> cost abatement curve to understand the implementation costs and social benefits in terms of <span class="hlt">air</span> quality improvement and greenhouse <span class="hlt">gas</span> abatement for each potential intervention. We anticipated such results could provide policy-maker insights in green city development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25920794','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25920794"><span>Characteristics of indoor radon and its progeny in a Japanese dwelling while using <span class="hlt">air</span> appliances.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pornnumpa, C; Tokonami, S; Sorimachi, A; Kranrod, C</p> <p>2015-11-01</p> <p>Characteristics of radon and its progeny were investigated in different <span class="hlt">air</span> conditions by turning four types of indoor <span class="hlt">air</span> appliances on and off in a two-story concrete Japanese dwelling. The four appliances were <span class="hlt">air</span> conditioner, <span class="hlt">air</span> cleaner, <span class="hlt">gas</span> heater and cooker hood. The measurements were done using two devices: (1) a Si-based semiconductor detector for continuous measurement of indoor radon <span class="hlt">concentration</span> and (2) a ZnS(Ag) scintillation counting system for equilibrium-equivalent radon <span class="hlt">concentration</span>. Throughout the entire experiment, the cooker hood was the most effective in decreasing indoor radon <span class="hlt">concentration</span> over a long period of time and the less effective was the <span class="hlt">air</span> conditioner, while the <span class="hlt">air</span> cleaner and <span class="hlt">gas</span> heater did not affect the <span class="hlt">concentration</span> of radon. However, the results measured in each <span class="hlt">air</span> condition will differ according to the lifestyles and activities of the inhabitants. In this study, indoor radon and its progeny in a Japanese dwelling will be characterised by the different <span class="hlt">air</span> conditions. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H11A1162P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H11A1162P"><span>High-resolution (noble) <span class="hlt">gas</span> time series for aquatic research</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Popp, A. L.; Brennwald, M. S.; Weber, U.; Kipfer, R.</p> <p>2017-12-01</p> <p>We developed a portable mass spectrometer (miniRUEDI) for on-site quantification of <span class="hlt">gas</span> <span class="hlt">concentrations</span> (He, Ar, Kr, N2, O2, CO2, CH4, etc.) in terrestrial gases [1,2]. Using the <span class="hlt">gas</span>-equilibrium membrane-inlet technique (GE-MIMS), the miniRUEDI for the first time also allows accurate on-site and long-term dissolved-<span class="hlt">gas</span> analysis in water bodies. The miniRUEDI is designed for operation in the field and at remote locations, using battery power and ambient <span class="hlt">air</span> as a calibration <span class="hlt">gas</span>. In contrast to conventional sampling and subsequent lab analysis, the miniRUEDI provides real-time and continuous time series of <span class="hlt">gas</span> <span class="hlt">concentrations</span> with a time resolution of a few seconds.Such high-resolution time series and immediate data availability open up new opportunities for research in highly dynamic and heterogeneous environmental systems. In addition the combined analysis of inert and reactive <span class="hlt">gas</span> species provides direct information on the linkages of physical and biogoechemical processes, such as the <span class="hlt">air</span>/water <span class="hlt">gas</span> exchange, excess <span class="hlt">air</span> formation, O2 turnover, or N2 production by denitrification [1,3,4].We present the miniRUEDI instrument and discuss its use for environmental research based on recent applications of tracking <span class="hlt">gas</span> dynamics related to rapid and short-term processes in aquatic systems. [1] Brennwald, M.S., Schmidt, M., Oser, J., and Kipfer, R. (2016). Environmental Science and Technology, 50(24):13455-13463, doi: 10.1021/acs.est.6b03669[2] Gasometrix GmbH, gasometrix.com[3] Mächler, L., Peter, S., Brennwald, M.S., and Kipfer, R. (2013). Excess <span class="hlt">air</span> formation as a mechanism for delivering oxygen to groundwater. Water Resources Research, doi:10.1002/wrcr.20547[4] Mächler, L., Brennwald, M.S., and Kipfer, R. (2013). Argon <span class="hlt">Concentration</span> Time-Series As a Tool to Study <span class="hlt">Gas</span> Dynamics in the Hyporheic Zone. Environmental Science and Technology, doi: 10.1021/es305309b</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A12C..01A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A12C..01A"><span>Understanding High Wintertime Ozone Events over an Oil and Natural <span class="hlt">Gas</span> Production Region from <span class="hlt">Air</span> Quality Model Perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ahmadov, R.; McKeen, S. A.; Trainer, M.; Banta, R. M.; Brown, S. S.; Edwards, P. M.; Frost, G. J.; Gilman, J.; Helmig, D.; Johnson, B.; Karion, A.; Koss, A.; Lerner, B. M.; Oltmans, S. J.; Roberts, J. M.; Schnell, R. C.; Veres, P. R.; Warneke, C.; Williams, E. J.; Wild, R. J.; Yuan, B.; Zamora, R. J.; Petron, G.; De Gouw, J. A.; Peischl, J.</p> <p>2014-12-01</p> <p>The huge increase in production of oil and natural <span class="hlt">gas</span> has been associated with high wintertime ozone events over some parts of the western US. The Uinta Basin, UT, where oil and natural <span class="hlt">gas</span> production is abundant experienced high ozone <span class="hlt">concentrations</span> in winters of recent years, when cold stagnant weather conditions were prevalent. It has been very challenging for conventional <span class="hlt">air</span> quality models to accurately simulate such wintertime ozone pollution cases. Here, a regional <span class="hlt">air</span> quality model study was successfully conducted for the Uinta Basin by using the WRF-Chem model. For this purpose a new emission dataset for the region's oil/<span class="hlt">gas</span> sector was built based on atmospheric in-situ measurements made during 2012 and 2013 field campaigns in the Uinta Basin. The WRF-Chem model demonstrates that the major factors driving high ozone in the Uinta Basin in winter are shallow boundary layers with light winds, high emissions of volatile organic compounds (VOC) compared to nitrogen oxides emissions from the oil and natural <span class="hlt">gas</span> industry, enhancement of photolysis rates and reduction of O3 dry deposition due to snow cover. We present multiple sensitivity simulations to quantify the contribution of various factors driving high ozone over the Uinta Basin. The emission perturbation simulations show that the photochemical conditions in the Basin during winter of 2013 were VOC sensitive, which suggests that targeting VOC emissions would be most beneficial for regulatory purposes. Shortcomings of the emissions within the most recent US EPA (NEI-2011, version 1) inventory are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26493981','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26493981"><span>Measurement of volatile plant compounds in field ambient <span class="hlt">air</span> by thermal desorption-<span class="hlt">gas</span> chromatography-mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cai, Xiao-Ming; Xu, Xiu-Xiu; Bian, Lei; Luo, Zong-Xiu; Chen, Zong-Mao</p> <p>2015-12-01</p> <p>Determination of volatile plant compounds in field ambient <span class="hlt">air</span> is important to understand chemical communication between plants and insects and will aid the development of semiochemicals from plants for pest control. In this study, a thermal desorption-<span class="hlt">gas</span> chromatography-mass spectrometry (TD-GC-MS) method was developed to measure ultra-trace levels of volatile plant compounds in field ambient <span class="hlt">air</span>. The desorption parameters of TD, including sorbent tube material, tube desorption temperature, desorption time, and cold trap temperature, were selected and optimized. In GC-MS analysis, the selected ion monitoring mode was used for enhanced sensitivity and selectivity. This method was sufficiently sensitive to detect part-per-trillion levels of volatile plant compounds in field ambient <span class="hlt">air</span>. Laboratory and field evaluation revealed that the method presented high precision and accuracy. Field studies indicated that the background odor of tea plantations contained some common volatile plant compounds, such as (Z)-3-hexenol, methyl salicylate, and (E)-ocimene, at <span class="hlt">concentrations</span> ranging from 1 to 3400 ng m(-3). In addition, the background odor in summer was more abundant in quality and quantity than in autumn. Relative to previous methods, the TD-GC-MS method is more sensitive, permitting accurate qualitative and quantitative measurements of volatile plant compounds in field ambient <span class="hlt">air</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8683885','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8683885"><span>[Contamination levels to room <span class="hlt">air</span> arising from the use of 99mTc-<span class="hlt">gas</span> and prevention from the contamination].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Komatani, A; Akutsu, T; Yamaguchi, K; Onodera, Y; Manaka, Y; Takahashi, K</p> <p>1996-04-01</p> <p>99mTc-<span class="hlt">gas</span> (TECHNEGAS) is a 99mTc-labeled micro-aerosol which is considered to have different behavior from 133Xe or 81mKr <span class="hlt">gas</span>. In order to estimate contamination levels to room <span class="hlt">air</span> arising from the use of 99mTc-<span class="hlt">gas</span>, filtered expired <span class="hlt">air</span> during administration and 1, 2, 3, 5, 10 min after the administration were collected in each polyethylene bag. Radioactivities of the polyethylene bags, used filter and the lung were measured with 3-head scintillation camera. The activity of the expired <span class="hlt">air</span> diminished within 6-10 min and about 5% of whole discharged 99mTc-<span class="hlt">gas</span> was released to room <span class="hlt">air</span>. The activity of the used filter was two times of the lung. According to these results, it is recommended that the 99mTc-<span class="hlt">gas</span> may be administrated in a exclusive room. The administrated patient and used filter must be remain in the exclusive room.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6800978-statistical-study-air-pollutant-concentrations-via-generalized-gamma-distribution','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6800978-statistical-study-air-pollutant-concentrations-via-generalized-gamma-distribution"><span>Statistical study of <span class="hlt">air</span> pollutant <span class="hlt">concentrations</span> via generalized gamma distribution</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Marani, A.; Lavagnini, I.; Buttazzoni, C.</p> <p>1986-11-01</p> <p>This paper deals with modeling observed frequency distributions of <span class="hlt">air</span> quality data measured in the area of Venice, Italy. The paper discusses the application of the generalized gamma distribution (ggd) which has not been commonly applied to <span class="hlt">air</span> quality data notwithstanding the fact that it embodies most distribution models used for <span class="hlt">air</span> quality analyses. The approach yields important simplifications for statistical analyses. A comparison among the ggd and other relevant models (standard gamma, Weibull, lognormal), carried out on daily sulfur dioxide <span class="hlt">concentrations</span> in the area of Venice underlines the efficiency of ggd models in portraying experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5179930','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5179930"><span>Flue-<span class="hlt">gas</span> and direct-<span class="hlt">air</span> capture of CO2 by porous metal–organic materials</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2017-01-01</p> <p>Sequestration of CO2, either from <span class="hlt">gas</span> mixtures or directly from <span class="hlt">air</span> (direct <span class="hlt">air</span> capture), is a technological goal important to large-scale industrial processes such as <span class="hlt">gas</span> purification and the mitigation of carbon emissions. Previously, we investigated five porous materials, three porous metal–organic materials (MOMs), a benchmark inorganic material, Zeolite 13X and a chemisorbent, TEPA-SBA-15, for their ability to adsorb CO2 directly from <span class="hlt">air</span> and from simulated flue-<span class="hlt">gas</span>. In this contribution, a further 10 physisorbent materials that exhibit strong interactions with CO2 have been evaluated by temperature-programmed desorption for their potential utility in carbon capture applications: four hybrid ultramicroporous materials, SIFSIX-3-Cu, DICRO-3-Ni-i, SIFSIX-2-Cu-i and MOOFOUR-1-Ni; five microporous MOMs, DMOF-1, ZIF-8, MIL-101, UiO-66 and UiO-66-NH2; an ultramicroporous MOM, Ni-4-PyC. The performance of these MOMs was found to be negatively impacted by moisture. Overall, we demonstrate that the incorporation of strong electrostatics from inorganic moieties combined with ultramicropores offers improved CO2 capture performance from even moist <span class="hlt">gas</span> mixtures but not enough to compete with chemisorbents. This article is part of the themed issue ‘Coordination polymers and metal–organic frameworks: materials by design’. PMID:27895255</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26838336','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26838336"><span>Valorization of Flue <span class="hlt">Gas</span> by Combining Photocatalytic <span class="hlt">Gas</span> Pretreatment with Microalgae Production.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Eynde, Erik Van; Lenaerts, Britt; Tytgat, Tom; Blust, Ronny; Lenaerts, Silvia</p> <p>2016-03-01</p> <p>Utilization of flue <span class="hlt">gas</span> for algae cultivation seems to be a promising route because flue <span class="hlt">gas</span> from fossil-fuel combustion processes contains the high amounts of carbon (CO2) and nitrogen (NO) that are required for algae growth. NO is a poor nitrogen source for algae cultivation because of its low reactivity and solublilty in water and its toxicity for algae at high <span class="hlt">concentrations</span>. Here, we present a novel strategy to valorize NO from flue <span class="hlt">gas</span> as feedstock for algae production by combining a photocatalytic <span class="hlt">gas</span> pretreatment unit with a microalgal photobioreactor. The photocatalytic <span class="hlt">air</span> pretreatment transforms NO <span class="hlt">gas</span> into NO2 <span class="hlt">gas</span> and thereby enhances the absorption of NOx in the cultivation broth. The absorbed NOx will form NO2(-) and NO3(-) that can be used as a nitrogen source by algae. The effect of photocatalytic <span class="hlt">air</span> pretreatment on the growth and biomass productivity of the algae Thalassiosira weissflogii in a semicontinuous system aerated with a model flue <span class="hlt">gas</span> (1% CO2 and 50 ppm of NO) is investigated during a long-term experiment. The integrated system makes it possible to produce algae with NO from flue <span class="hlt">gas</span> as the sole nitrogen source and reduces the NOx content in the exhaust <span class="hlt">gas</span> by 84%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28873626','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28873626"><span>Effectiveness of water-<span class="hlt">air</span> and octanol-<span class="hlt">air</span> partition coefficients to predict lipophilic flavor release behavior from O/W emulsions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tamaru, Shunji; Igura, Noriyuki; Shimoda, Mitsuya</p> <p>2018-01-15</p> <p>Flavor release from food matrices depends on the partition of volatile flavor compounds between the food matrix and the vapor phase. Thus, we herein investigated the relationship between released flavor <span class="hlt">concentrations</span> and three different partition coefficients, namely octanol-water, octanol-<span class="hlt">air</span>, and water-<span class="hlt">air</span>, which represented the oil, water, and <span class="hlt">air</span> phases present in emulsions. Limonene, 2-methylpyrazine, nonanal, benzaldehyde, ethyl benzoate, α-terpineol, benzyl alcohol, and octanoic acid were employed. The released <span class="hlt">concentrations</span> of these flavor compounds from oil-in-water (O/W) emulsions were measured under equilibrium using static headspace <span class="hlt">gas</span> chromatography. The results indicated that water-<span class="hlt">air</span> and octanol-<span class="hlt">air</span> partition coefficients correlated with the logarithms of the released <span class="hlt">concentrations</span> in the headspace for highly lipophilic flavor compounds. Moreover, the same tendency was observed over various oil volume ratios in the emulsions. Our findings therefore suggest that octanol-<span class="hlt">air</span> and water-<span class="hlt">air</span> partition coefficients can be used to predict the released <span class="hlt">concentration</span> of lipophilic flavor compounds from O/W emulsions. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29493206','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29493206"><span>Toward Adequate Operation of Amorphous Oxide Thin-Film Transistors for Low-<span class="hlt">Concentration</span> <span class="hlt">Gas</span> Detection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Kyung Su; Ahn, Cheol Hyoun; Jung, Sung Hyeon; Cho, Sung Woon; Cho, Hyung Koun</p> <p>2018-03-28</p> <p>We suggest the use of a thin-film transistor (TFT) composed of amorphous InGaZnO (a-IGZO) as a channel and a sensing layer for low-<span class="hlt">concentration</span> NO 2 <span class="hlt">gas</span> detection. Although amorphous oxide layers have a restricted surface area when reacting with NO 2 <span class="hlt">gas</span>, such TFT sensors have incomparable advantages in the aspects of electrical stability, large-scale uniformity, and the possibility of miniaturization. The a-IGZO thin films do not possess typical reactive sites and grain boundaries, so that the variation in drain current of the TFTs strictly originates from oxidation reaction between channel surface and NO 2 <span class="hlt">gas</span>. Especially, the sensing data obtained from the variation rate of drain current makes it possible to monitor efficiently and quickly the variation of the NO 2 <span class="hlt">concentration</span>. Interestingly, we found that enhancement-mode TFT (EM-TFT) allows discrimination of the drain current variation rate at NO 2 <span class="hlt">concentrations</span> ≤10 ppm, whereas a depletion-mode TFT is adequate for discriminating NO 2 <span class="hlt">concentrations</span> ≥10 ppm. This discrepancy is attributed to the ratio of charge carriers contributing to <span class="hlt">gas</span> capture with respect to total carriers. This capacity for the excellent detection of low-<span class="hlt">concentration</span> NO 2 <span class="hlt">gas</span> can be realized through (i) three-terminal TFT <span class="hlt">gas</span> sensors using amorphous oxide, (ii) measurement of the drain current variation rate for high selectivity, and (iii) an EM mode driven by tuning the electrical conductivity of channel layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/816066','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/816066"><span>Predicting indoor pollutant <span class="hlt">concentrations</span>, and applications to <span class="hlt">air</span> quality management</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lorenzetti, David M.</p> <p></p> <p>Because most people spend more than 90% of their time indoors, predicting exposure to airborne pollutants requires models that incorporate the effect of buildings. Buildings affect the exposure of their occupants in a number of ways, both by design (for example, filters in ventilation systems remove particles) and incidentally (for example, sorption on walls can reduce peak <span class="hlt">concentrations</span>, but prolong exposure to semivolatile organic compounds). Furthermore, building materials and occupant activities can generate pollutants. Indoor <span class="hlt">air</span> quality depends not only on outdoor <span class="hlt">air</span> quality, but also on the design, maintenance, and use of the building. For example, ''sick building'' symptomsmore » such as respiratory problems and headaches have been related to the presence of <span class="hlt">air</span>-conditioning systems, to carpeting, to low ventilation rates, and to high occupant density (1). The physical processes of interest apply even in simple structures such as homes. Indoor <span class="hlt">air</span> quality models simulate the processes, such as ventilation and filtration, that control pollutant <span class="hlt">concentrations</span> in a building. Section 2 describes the modeling approach, and the important transport processes in buildings. Because advection usually dominates among the transport processes, Sections 3 and 4 describe methods for predicting airflows. The concluding section summarizes the application of these models.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8338613','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8338613"><span>[The effect of the ventilation rate on <span class="hlt">air</span> particle and <span class="hlt">air</span> microbe <span class="hlt">concentration</span> in operating rooms with conventional ventilation. 1. Measurement without surgical activity].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kruppa, B; Rüden, H</p> <p>1993-05-01</p> <p>The question was if a reduction of airborne particles and bacteria in conventionally (turbulently), ventilated operating theatres in comparison to Laminar-Airflow (LAF) operating theatres does occur at high <span class="hlt">air</span>-exchange-rates. Within the framework of energy consumption measures the influence of <span class="hlt">air</span>-exchange-rates on airborne particle and bacteria <span class="hlt">concentrations</span> was determined in two identical operating theatres with conventional ventilation (wall diffusor panel) at the <span class="hlt">air</span>-exchange-rates 7.5, 10, 15 and 20/h without surgical activity. This was established by means of the statistical procedure of analysis of variance. Especially for the comparison of the <span class="hlt">air</span>-exchange-rates 7.5 and 15/h statistical differences were found for airborne particle <span class="hlt">concentrations</span> in supply and ambient <span class="hlt">air</span>. Concerning airborne bacteria <span class="hlt">concentrations</span> no differences were found among the various <span class="hlt">air</span>-exchange-rates. Explanation of variance is quite high for non-viable particles (supply <span class="hlt">air</span>: 37%, ambient <span class="hlt">air</span>: 81%) but negligible for viable particles (bacteria) with values below 15%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....2722W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....2722W"><span><span class="hlt">Gas</span> geochemistry studies at the <span class="hlt">gas</span> hydrate occurrence in the permafrost environment of Mallik (NWT, Canada)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wiersberg, T.; Erzinger, J.; Zimmer, M.; Schicks, J.; Dahms, E.; Mallik Working Group</p> <p>2003-04-01</p> <p>We present real-time mud <span class="hlt">gas</span> monitoring data as well as results of noble <span class="hlt">gas</span> and isotope investigations from the Mallik 2002 Production Research Well Program, an international research project on <span class="hlt">Gas</span> Hydrates in the Northwest Territories of Canada. The program participants include 8 partners; The Geological Survey of Canada (GSC), The Japan National Oil Corporation (JNOC), GeoForschungsZentrum Potsdam (GFZ), United States Geological Survey (USGS), United States Department of the Energy (USDOE), India Ministry of Petroleum and Natural <span class="hlt">Gas</span> (MOPNG)/<span class="hlt">Gas</span> Authority of India (GAIL) and the Chevron-BP-Burlington joint venture group. Mud <span class="hlt">gas</span> monitoring (extraction of <span class="hlt">gas</span> dissolved in the drill mud followed by real-time analysis) revealed more or less complete <span class="hlt">gas</span> depth profiles of Mallik 4L-38 and Mallik 5L-38 wells for N_2, O_2, Ar, He, CO_2, H_2, CH_4, C_2H_6, C_3H_8, C_4H10, and 222Rn; both wells are approx. 1150 m deep. Based on the molecular and and isotopic composition, hydrocarbons occurring at shallow depth (down to ˜400 m) are mostly of microbial origin. Below 400 m, the <span class="hlt">gas</span> wetness parameter (CH_4/(C_2H_6 + C_3H_8)) and isotopes indicate mixing with thermogenic <span class="hlt">gas</span>. <span class="hlt">Gas</span> accumulation at the base of permafrost (˜650 m) as well as δ13C and helium isotopic data implies that the permafrost inhibits <span class="hlt">gas</span> flux from below. <span class="hlt">Gas</span> hydrate occurrence at Mallik is known in a depth between ˜890 m and 1100 m. The upper section of the hydrate bearing zone (890 m--920 m) consists predominantly of methane bearing <span class="hlt">gas</span> hydrates. Between 920 m and 1050 m, <span class="hlt">concentration</span> of C_2H_6, C_3H_8, and C_4H10 increases due to the occurrence of organic rich sediment layers. Below that interval, the <span class="hlt">gas</span> composition is similar to the upper section of the hydrate zone. At the base of the hydrate bearing zone (˜1100 m), elevated helium and methane <span class="hlt">concentrations</span> and their isotopic composition leads to the assumption that <span class="hlt">gas</span> hydrates act as a barrier for <span class="hlt">gas</span> migration from below. In mud <span class="hlt">gas</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27209375','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27209375"><span><span class="hlt">Gas</span> Exchange Models for a Flexible Insect Tracheal System.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Simelane, S M; Abelman, S; Duncan, F D</p> <p>2016-06-01</p> <p>In this paper two models for movement of respiratory gases in the insect trachea are presented. One model considers the tracheal system as a single flexible compartment while the other model considers the trachea as a single flexible compartment with <span class="hlt">gas</span> exchange. This work represents an extension of Ben-Tal's work on compartmental <span class="hlt">gas</span> exchange in human lungs and is applied to the insect tracheal system. The purpose of the work is to study nonlinear phenomena seen in the insect respiratory system. It is assumed that the flow inside the trachea is laminar, and that the <span class="hlt">air</span> inside the chamber behaves as an ideal <span class="hlt">gas</span>. Further, with the isothermal assumption, the expressions for the tracheal partial pressures of oxygen and carbon dioxide, rate of volume change, and the rates of change of oxygen <span class="hlt">concentration</span> and carbon dioxide <span class="hlt">concentration</span> are derived. The effects of some flow parameters such as diffusion capacities, reaction rates and <span class="hlt">air</span> <span class="hlt">concentrations</span> on net flow are studied. Numerical simulations of the tracheal flow characteristics are performed. The models developed provide a mathematical framework to further investigate <span class="hlt">gas</span> exchange in insects.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/867867','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/867867"><span>External combustor for <span class="hlt">gas</span> turbine engine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Santanam, Chandran B.; Thomas, William H.; DeJulio, Emil R.</p> <p>1991-01-01</p> <p>An external combustor for a <span class="hlt">gas</span> turbine engine has a cyclonic combustion chamber into which combustible <span class="hlt">gas</span> with entrained solids is introduced through an inlet port in a primary spiral swirl. A metal draft sleeve for conducting a hot <span class="hlt">gas</span> discharge stream from the cyclonic combustion chamber is mounted on a circular end wall of the latter adjacent the combustible <span class="hlt">gas</span> inlet. The draft sleeve is mounted <span class="hlt">concentrically</span> in a cylindrical passage and cooperates with the passage in defining an annulus around the draft sleeve which is open to the cyclonic combustion chamber and which is connected to a source of secondary <span class="hlt">air</span>. Secondary <span class="hlt">air</span> issues from the annulus into the cyclonic combustion chamber at a velocity of three to five times the velocity of the combustible <span class="hlt">gas</span> at the inlet port. The secondary <span class="hlt">air</span> defines a hollow cylindrical extension of the draft sleeve and persists in the cyclonic combustion chamber a distance of about three to five times the diameter of the draft sleeve. The hollow cylindrical extension shields the drive sleeve from the inlet port to prevent discharge of combustible <span class="hlt">gas</span> through the draft sleeve.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=59523&keyword=CAPS&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=59523&keyword=CAPS&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>EFFECTS OF METAL COMPONENTS IN <span class="hlt">CONCENTRATED</span> AMBIENT <span class="hlt">AIR</span> PARTICLES ON PULMONARY INJURY</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>EFFECTS OF METAL COMPONENTS IN <span class="hlt">CONCENTRATED</span> AMBIENT <span class="hlt">AIR</span> PARTICLES ON PULMONARY INJURY. Yuh-Chin Huang, Jackie Stonehuerner, Jackie Carter, Andrew J. Ghio, Robert B. Devlin. NHEERL, US EPA, RTP, NC.<br>The mechanisms for cardiopulmonary morbidity associated with exposure to <span class="hlt">air</span> po...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17674350','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17674350"><span><span class="hlt">Air</span> bells of water spiders are an extended phenotype modified in response to <span class="hlt">gas</span> composition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schütz, Dolores; Taborsky, Michael; Drapela, Thomas</p> <p>2007-10-01</p> <p>The water spider Argyroneta aquatica (Clerck) is the only spider that spends its whole life under water. Water spiders keep an <span class="hlt">air</span> bubble around their body for breathing and build under-water <span class="hlt">air</span> bells, which they use for shelter and raising offspring, digesting and consuming prey, moulting, depositing eggs and sperm, and copulating. It is unclear whether these bells are an important oxygen reservoir for breathing under water, or whether they serve mainly to create water-free space for feeding and reproduction. In this study, we manipulated the composition of the <span class="hlt">gas</span> inside the bell of female water spiders to test whether they monitor the quality of this <span class="hlt">gas</span>, and replenish oxygen if required. We exchanged the entire <span class="hlt">gas</span> in the bell either with pure O2, pure CO2, or with ambient <span class="hlt">air</span> as control, and monitored behavioural responses. The test spiders surfaced and replenished <span class="hlt">air</span> more often in the CO2 treatment than in the O2 treatment, and they increased bell building behaviour. In addition to active oxygen regulation, they monitored and adjusted the bells by adding silk. These results show that water spiders use the <span class="hlt">air</span> bell as an oxygen reservoir, and that it functions as an external lung, which renders it essential for living under water permanently. A. aquatica is the only animal that collects, transports, and stores <span class="hlt">air</span>, and monitors its property for breathing, which is an adaptive response of a terrestrial animal to the colonization of an aquatic habitat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29353429','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29353429"><span>A sensitive method using SPME pre-<span class="hlt">concentration</span> for the quantification of aromatic amines in indoor <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lucaire, Vincent; Schwartz, Jean-Jacques; Delhomme, Olivier; Ocampo-Torres, Ruben; Millet, Maurice</p> <p>2018-03-01</p> <p>Monitoring the levels of aliphatic and aromatic amines (AA) in indoor <span class="hlt">air</span> is important to protect human health because of exposure to these compounds through diet and inhalation. A sampling and analytical method using XAD-2 cartridges and <span class="hlt">gas</span> chromatography coupled to mass spectrometry used for assessing 25 AA in different smoking and non-smoking indoor environment was developed. After sampling and delivering 1 m 3 of <span class="hlt">air</span> (6-8 h sampling), an adsorbent was ultrasonically extracted with acetonitrile, <span class="hlt">concentrated</span> to 1 mL and diluted in 25 mL of water (pH = 9; 5% NaCl), and then extracted for 40 min at 80 °C using a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber and injected in a GC/MS system. With this method, 22 of the 25 AA can be analyzed with detection limits up to five times lower than that of classic liquid injection. Benzylamine, 3-aminophenol, and 4-aminophenol were not detected with the solid-phase micro-extraction (SPME) method. It can be assumed that aminophenols required a derivatization step for their analysis by GC as these molecules were not detected regardless of the injection mode used. Graphical abstract Analysis of aromatic amines in indoor <span class="hlt">air</span> by SPME-GC/MS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009nrb..book..265R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009nrb..book..265R"><span><span class="hlt">Air</span> Pollution Monitoring and Use of Nanotechnology Based Solid State <span class="hlt">Gas</span> Sensors in Greater Cairo Area, Egypt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramadan, A. B. A.</p> <p></p> <p><span class="hlt">Air</span> pollution is a serious problem in thickly populated and industrialized areas in Egypt, especially in greater Cairo area. Economic growth and industrialization are proceeding at a rapid pace, accompanied by increasing emissions of <span class="hlt">air</span> polluting sources. Furthermore, though the variety and quantities of polluting sources have increased dramatically, the development of a suitable method for monitoring the pollution causing sources has not followed at the same pace. Environmental impacts of <span class="hlt">air</span> pollutants have impact on public health, vegetation, material deterioration etc. To prevent or minimize the damage caused by atmospheric pollution, suitable monitoring systems are urgently needed that can rapidly and reliably detect and quantify polluting sources for monitoring by regulating authorities in order to prevent further deterioration of the current pollution levels. Consequently, it is important that the current real-time <span class="hlt">air</span> quality monitoring system, controlled by the Egyptian Environmental Affairs Agency (EEAA), should be adapted or extended to aid in alleviating this problem. Nanotechnology has been applied to several industrial and domestic fields, for example, applications for <span class="hlt">gas</span> monitoring systems, <span class="hlt">gas</span> leak detectors in factories, fire and toxic <span class="hlt">gas</span> detectors, ventilation control, breath alcohol detectors, and the like. Here we report an application example of studying <span class="hlt">air</span> quality monitoring based on nanotechnology `solid state <span class="hlt">gas</span> sensors'. So as to carry out <span class="hlt">air</span> pollution monitoring over an extensive area, a combination of ground measurements through inexpensive sensors and wireless GIS will be used for this purpose. This portable device, comprising solid state <span class="hlt">gas</span> sensors integrated to a Personal Digital Assistant (PDA) linked through Bluetooth communication tools and Global Positioning System (GPS), will allow rapid dissemination of information on pollution levels at multiple sites simultaneously.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70017931','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70017931"><span>Relationships between 222Rn dissolved in ground water supplies and indoor 222Rn <span class="hlt">concentrations</span> in some Colorado front range houses</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Folger, P.F.; Nyberg, P.; Wanty, R.B.; Poeter, E.</p> <p>1994-01-01</p> <p>Indoor 222Rn <span class="hlt">concentrations</span> were measured in 37 houses with alpha track detectors placed in water-use rooms near water sources (bathrooms, laundry rooms, and kitchens) and in non-water-use living rooms, dining rooms, and bedrooms away from water sources. Results show that relative contributions of 222Rn to indoor <span class="hlt">air</span> from water use are insignificant when soil-<span class="hlt">gas</span> <span class="hlt">concentrations</span> are high but become increasingly important as the ratio of 222Rn-in-water:222Rn-in-soil <span class="hlt">gas</span> increases. High soil-<span class="hlt">gas</span> 222Rn <span class="hlt">concentrations</span> may mask 222Rn contributions from water even when waterborne 222Rn <span class="hlt">concentrations</span> are as high as 750 kBq m-3. Ground water in Precambrian Pikes Peak granite averages 340 kBq m-3222Rn, vs. 170 kBq m-3 in Precambrian migmatite, but average 222Rn <span class="hlt">concentrations</span> in soil <span class="hlt">gas</span> are also lower in migmatite. Because the ratio of 222Rn-in- water:222Rn-in-soil <span class="hlt">gas</span> may be consistently higher for houses in migmatite than in Pikes Peak granite, indoor <span class="hlt">air</span> in houses built on migmatite may have a greater relative contribution from water use even though average 222Rn <span class="hlt">concentrations</span> in the water are lower. Continuous monitoring of 222Rn <span class="hlt">concentrations</span> in <span class="hlt">air</span> on 15-min intervals also indicates that additions to indoor <span class="hlt">concentrations</span> from water use are significant and measurable only when soil-<span class="hlt">gas</span> <span class="hlt">concentrations</span> are low and <span class="hlt">concentrations</span> in water are high. When soil-<span class="hlt">gas</span> <span class="hlt">concentrations</span> were mitigated to less than 150 Bq m-3 in one house, water contributes 20-40% of the annual indoor 222Rn <span class="hlt">concentration</span> in the laundry room (222Rn <span class="hlt">concentration</span> in water of 670 kBq m-3). Conversely, when the mitigation system is inactive, diurnal fluctuations and other variations in the soil-<span class="hlt">gas</span> 222Rn contribution swamp the variability due to water use in the house. Measurable variations in indoor <span class="hlt">concentrations</span> from water use were not detected in one house despite a low soil-<span class="hlt">gas</span> contribution of approximately 150 Bq m-3 because waterborne 222Rn <span class="hlt">concentrations</span> also are low (80 kBq m-3). This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12..463U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12..463U"><span>Evaluation of anthropogenic influence on thermodynamics, <span class="hlt">gas</span> and aerosol composition of city <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Uzhegova, Nina; Belan, Boris; Antokhin, Pavel; Zhidovkhin, Evgenii; Ivlev, Georgii; Kozlov, Artem; Fofonov, Aleksandr</p> <p>2010-05-01</p> <p>In the last 40-50 years there is a global tendency of urbanisation, which is a consequence of most countries' economical development. Concurrently, the issue of environment's ecological state has become critical. Urban <span class="hlt">air</span> pollution is among the most important ecological problems nowadays. World Health Organization (WHO) points out certain "classical" polluting agents: carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), sulphur dioxide (SO2), troposphere ozone (O3) (studied here), as well as lead, carbon dioxide (CO2), aldehydes, soot, benzpyrene and dredges (including dust, haze and smoke) [1]. An evaluation of antropogenic component's weight in the thermodynamical conditions and <span class="hlt">gas</span> and aerosol composition of a city's atmosphere (by the example of Tomsk) is given in this paper. Tomsk is located at the South of West Siberia and is the administrative center of Tomsk region. The city's area is equal to 294,6 km2. Its population is 512.6 thousands of people. The overall number of registered motor vehicles in the city in 2008 was 131 700. That is, every fourth city inhabitant has a personal car. From 2002 to 2008 the number of motor vehicles in Tomsk has increased by 25 thousands units [2]. This increase consists mostly of passenger cars. There is also a positive trend in fuel consumtion by the city's industries and motor vehicles - from 2004 to 2007 it has increased by 10%. Such a quick rate of transport quantity's increase in the city provides reason to suggest an unfavorable ecological situation in Tomsk. For this study we have used the AKV-2 mobile station designed by the SB RAS Institute of Atmospheric Optics. The station's equipment provides the following measurements [3]: <span class="hlt">air</span> temperature and humidity; aerosol disperse composition in 15 channels with a particle size range of 0.3-20 µm by use of the Grimm-1.108 aerosol spectrometer; NO, NO2, O3, SO2, CO, CO2 <span class="hlt">concentration</span>. This paper describes a single experiment conducted in Tomsk. Date of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C21D1148J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C21D1148J"><span>90-year-old firn <span class="hlt">air</span> from Styx glacier, East Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jang, Y.; Ahn, J.; Buizert, C.; Lee, H. G.; Hong, S.; Han, Y.; Jun, S. J.; Hur, S. D.</p> <p>2017-12-01</p> <p>Firn is the upper part of the glacier that has not yet been completely changed to the ice. In this layer, firn <span class="hlt">air</span> can move through the open pores and be pumped for sampling. We obtained firn <span class="hlt">air</span> and ice cores from Styx glacier (73°51'95″ S, 163°41'217″ E, 1623m asl.), East Antarctica during 2014-2015. The Styx glacier is located near coast, and has an accumulation rate of 0.13 Mgm-2y-1 with a mean annual temperature of -31.7 °. We found that the lock-in depth (depth where <span class="hlt">gas</span> diffusion starts to stop, "LID") is 52.4 m and bubble close-off depth (the depth to the snow-ice transition perfectly, "COD") is 65.1 m. Therefore lock-in zone (between LID and COD, "LIZ") is 52.4 - 65.1 m. <span class="hlt">Concentrations</span> of greenhouse gases (CO2, CH4, n=13) in the firn <span class="hlt">air</span> were analyzed at US National Oceanic and Atmospheric Administration (NOAA) and 15N of N2 was measured at the Scripps Institution of Oceanography (SIO). We find that the firn <span class="hlt">air</span> ages are up to about 90 years, the oldest firn <span class="hlt">air</span> ages observed among coastal glaciers. In order to better understand physical properties and chemical composition, methane <span class="hlt">concentration</span> and total <span class="hlt">air</span> content of the closed bubbles in the LIZ (3 cm resolution, n=124) were analyzed by a wet extraction method at Seoul National University. The CH4 <span class="hlt">concentration</span> and total <span class="hlt">air</span> content show large variations in cm-scale depth intervals, and they are anti-correlated with each other. The CH4 <span class="hlt">concentration</span> changes in a few cm corresponds to up to 40 years in CH4 age. We also applied Centre for Ice and Climate (CIC) 1-dimensional diffusion model and simulated greenhouse <span class="hlt">gas</span> <span class="hlt">concentration</span> profiles to quantitatively understand how the <span class="hlt">air</span> moves in the Styx firn column. We hypothesize that density variations in the firn may increase thickness of LIZ and consequently increase of firn <span class="hlt">gas</span> ages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26ES..150a2002R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26ES..150a2002R"><span>Modeling <span class="hlt">air</span> <span class="hlt">concentration</span> over macro roughness conditions by Artificial Intelligence techniques</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roshni, T.; Pagliara, S.</p> <p>2018-05-01</p> <p>Aeration is improved in rivers by the turbulence created in the flow over macro and intermediate roughness conditions. Macro and intermediate roughness flow conditions are generated by flows over block ramps or rock chutes. The measurements are taken in uniform flow region. Efficacy of soft computing methods in modeling hydraulic parameters are not common so far. In this study, modeling efficiencies of MPMR model and FFNN model are found for estimating the <span class="hlt">air</span> <span class="hlt">concentration</span> over block ramps under macro roughness conditions. The experimental data are used for training and testing phases. Potential capability of MPMR and FFNN model in estimating <span class="hlt">air</span> <span class="hlt">concentration</span> are proved through this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/874548','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/874548"><span>Cooling <span class="hlt">air</span> recycling for <span class="hlt">gas</span> turbine transition duct end frame and related method</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Cromer, Robert Harold; Bechtel, William Theodore; Sutcu, Maz</p> <p>2002-01-01</p> <p>A method of cooling a transition duct end frame in a <span class="hlt">gas</span> turbine includes the steps of a) directing cooling <span class="hlt">air</span> into the end frame from a region external of the transition duct and the impingement cooling sleeve; and b) redirecting the cooling <span class="hlt">air</span> from the end frame into the annulus between the transition duct and the impingement cooling sleeve.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020079090','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020079090"><span><span class="hlt">Air</span> Quality Monitor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1996-01-01</p> <p>The Stak-Tracker CEM (Continuous Emission Monitor) <span class="hlt">Gas</span> Analyzer is an <span class="hlt">air</span> quality monitor capable of separating the various gases in a bulk exhaust stream and determining the amounts of individual gases present within the stream. The monitor is produced by GE Reuter- Stokes, a subsidiary of GE Corporate Research & Development Center. The Stak-Tracker uses a Langley Research Center software package which measures the <span class="hlt">concentration</span> of a target <span class="hlt">gas</span> by determining the degree to which molecules of that <span class="hlt">gas</span> absorb an infrared beam. The system is environmental-friendly, fast and has relatively low installation and maintenance costs. It is applicable to <span class="hlt">gas</span> turbines and various industries including glass, paper and cement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010082932&hterms=water+purification&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwater%2Bpurification','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010082932&hterms=water+purification&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwater%2Bpurification"><span>Regenerable <span class="hlt">Air</span> Purification System for <span class="hlt">Gas</span>-Phase Contaminant Control</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Constantinescu, Ileana C.; Qi, Nan; LeVan, M. Douglas; Finn, Cory K.; Finn, John E.; Luna, Bernadette (Technical Monitor)</p> <p>2000-01-01</p> <p>A regenerable <span class="hlt">air</span> purification system (RAPS) that uses water vapor to displace adsorbed contaminants from an. adsorbent column into a closed oxidation loop is under development through cooperative R&D between Vanderbilt University and NASA Ames Research Center. A unit based on this design can be used for removing trace <span class="hlt">gas</span>-phase contaminants from spacecraft cabin <span class="hlt">air</span> or from polluted process streams including incinerator exhaust. Recent work has focused on fabrication and operation of a RAPS breadboard at NASA Ames, and on measurement of adsorption isotherm data for several important organic compounds at Vanderbilt. These activities support the use and validation of RAPS modeling software also under development at Vanderbilt, which will in turn be used to construct a prototype system later in the project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989TepVT..27..226M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989TepVT..27..226M"><span>Electron <span class="hlt">concentration</span> distribution in a glow discharge in <span class="hlt">air</span> flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mukhamedzianov, R. B.; Gaisin, F. M.; Sabitov, R. A.</p> <p>1989-04-01</p> <p>Electron <span class="hlt">concentration</span> distributions in a glow discharge in longitudinal and vortex <span class="hlt">air</span> flows are determined from the attenuation of the electromagnetic wave passing through the plasma using microwave probes. An analysis of the distribution curves obtained indicates that electron <span class="hlt">concentration</span> decreases in the direction of the anode. This can be explained by charge diffusion toward the chamber walls and electron recombination and sticking within the discharge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.2894B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.2894B"><span>Influence of the meteorological parameters on CFCs and SF6 <span class="hlt">concentration</span> in the <span class="hlt">air</span> of Krakow, Poland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bielewski, Jarosław; Najman, Joanna; Śliwka, Ireneusz; Bartyzel, Jakub; Rosiek, Janusz</p> <p>2013-04-01</p> <p>key words: <span class="hlt">gas</span> chromatography, trace gases, CFCs and SF6 measurements in urban area. Halogenated compounds (chlorofluorocarbons-CFCs), both natural and industrial, so-called freons, currently exist as trace gases in the entire human environment. The CFCs cause ozone depletion in the stratosphere. Moreover CFCs and SF6 take part in intensification of the greenhouse effect. The decisions of the Vienna Convention (1985) and of the Montreal Protocol (1987) limited the world production level of CFCs in the year 1989 at least 35% after 2004, 90% after 2015 and total reduction after year 2030. On account of international agreements, the measurements of CFCs and SF6 in <span class="hlt">air</span> were started. Measurement "clean" stations were situated at places outside of urban areas influence and gathered on world program - AGAGE (Advanced Global Atmospheric Gases Experiment). One of these stations is Mace Head (Ireland, 53o N, 10o W), which participates in AGAGE since 1987 [1] and in European InGOS (Integrated non-CO2 Greenhouse <span class="hlt">gas</span> Observing System) program since 2011. Similar research is also conducted in Central Europe, in urban area of Krakow (Poland, 50o N, 19o E) since 1997. The work discusses results from 15 years of <span class="hlt">concentration</span> measurements (in the years 1997-2012) of selected halocarbons and SF6 in Krakow. To obtain <span class="hlt">concentrations</span> of measured compounds the mathematical procedure has been used, where <span class="hlt">concentrations</span> were calculated using a five points Lagrange's interpolation method. Using temporary measurement data were determined daily arithmetic means and their standard deviations. Based on these data, efficiency of Montreal Protocol legislation, implemented in Poland (The Journal of Laws No. 52) could be assessed [2]. Additionally cut-off filtration method was used to estimate trend of the base line of individual <span class="hlt">air</span> pollutant. Rejected exceedances of base lines were corelated with meteorological characteristics of Krakow region to evaluate possible sources of pollution. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14501419','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14501419"><span>Hydrofluoric acid burn resulting from ignition of <span class="hlt">gas</span> from a compressed <span class="hlt">air</span> duster.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Foster, Kevin N; Jones, LouAnn; Caruso, Daniel M</p> <p>2003-01-01</p> <p>A young female suffered burns to her hand after the ignition of <span class="hlt">gas</span> from a compressed <span class="hlt">air</span> duster. After debridement and dressing, the patient continued to have pain out of proportion to injury that was refractory to intravenous morphine. The material safety data sheet revealed that the chemical used was 1,1-difluoroethane. High temperatures can cause decompensation to form hydrofluoric acid. Calcium gluconate gel was applied topically to the patient's burns, which caused prompt and complete relief of her pain. A review of different compressed <span class="hlt">air</span> duster products revealed that the main ingredient in each was a halogenated hydrocarbon. Although not considered flammable, all products have warnings regarding the possibility of ignition under various circumstances. Ignition of the <span class="hlt">gas</span> in compressed <span class="hlt">air</span> cleaners not only can cause flame burns, it can also cause chemical damage from exposure to hydrogen and fluoride ions. Prompt recognition and treatment is necessary to prevent severe injury.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29708730','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29708730"><span>Development of a High-Resolution Laser Absorption Spectroscopy Method with Application to the Determination of Absolute <span class="hlt">Concentration</span> of Gaseous Elemental Mercury in <span class="hlt">Air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Srivastava, Abneesh; Hodges, Joseph T</p> <p>2018-06-05</p> <p>Isotope dilution-cold-vapor-inductively coupled plasma mass spectrometry (ID-CV-ICPMS) has become the primary standard for measurement of gaseous elemental mercury (GEM) mass <span class="hlt">concentration</span>. However, quantitative mass spectrometry is challenging for several reasons including (1) the need for isotopic spiking with a standard reference material, (2) the requirement for bias-free passive sampling protocols, (3) the need for stable mass spectrometry interface design, and (4) the time and cost involved for <span class="hlt">gas</span> sampling, sample processing, and instrument calibration. Here, we introduce a high-resolution laser absorption spectroscopy method that eliminates the need for sample-specific calibration standards or detailed analysis of sample treatment losses. This technique involves a tunable, single-frequency laser absorption spectrometer that measures isotopically resolved spectra of elemental mercury (Hg) spectra of 6 1 S 0 ← 6 3 P 1 intercombination transition near λ = 253.7 nm. Measured spectra are accurately modeled from first-principles using the Beer-Lambert law and Voigt line profiles combined with literature values for line positions, line shape parameters, and the spontaneous emission Einstein coefficient to obtain GEM mass <span class="hlt">concentration</span> values. We present application of this method for the measurement of the equilibrium <span class="hlt">concentration</span> of mercury vapor near room temperature. Three closed systems are considered: two-phase mixtures of liquid Hg and its vapor and binary two-phase mixtures of Hg-<span class="hlt">air</span> and Hg-N 2 near atmospheric pressure. Within the experimental relative standard uncertainty, 0.9-1.5% congruent values of the equilibrium Hg vapor <span class="hlt">concentration</span> are obtained for the Hg-only, Hg-<span class="hlt">air</span>, Hg-N 2 systems, in confirmation with thermodynamic predictions. We also discuss detection limits and the potential of the present technique to serve as an absolute primary standard for measurements of <span class="hlt">gas</span>-phase mercury <span class="hlt">concentration</span> and isotopic composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28577146','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28577146"><span>Historical and future emission of hazardous <span class="hlt">air</span> pollutants (HAPs) from <span class="hlt">gas</span>-fired combustion in Beijing, China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xue, Yifeng; Nie, Lei; Zhou, Zhen; Tian, Hezhong; Yan, Jing; Wu, Xiaoqing; Cheng, Linglong</p> <p>2017-07-01</p> <p>The consumption of natural <span class="hlt">gas</span> in Beijing has increased in the past decade due to energy structure adjustments and <span class="hlt">air</span> pollution abatement. In this study, an integrated emission inventory of hazardous <span class="hlt">air</span> pollutants (HAPs) emitted from <span class="hlt">gas</span>-fired combustion in Beijing was developed for the period from 2000 to 2014 using a technology-based approach. Future emission trends were projected through 2030 based on current energy-related and emission control policies. We found that emissions of primary HAPs exhibited an increasing trend with the rapid increase in natural <span class="hlt">gas</span> consumption. Our estimates indicated that the total emissions of NO X , particulate matter (PM) 10 , PM 2.5 , CO, VOCs, SO 2 , black carbon, Pb, Cd, Hg, As, Cr, Cu, Ni, Zn, polychlorinated dibenzo-p-dioxins and dibenzofurans, and benzo[a]pyrene from <span class="hlt">gas</span>-fired combustion in Beijing were approximately 22,422 t, 1042 t, 781 t, 19,097 t, 653 t, 82 t, 19 t, 0.6 kg, 0.1 kg, 43 kg, 52 kg, 0.3 kg, 0.03 kg, 4.3 kg, 0.6 kg, 216 μg, and 242 g, respectively, in 2014. To mitigate the associated <span class="hlt">air</span> pollution and health risks caused by <span class="hlt">gas</span>-fired combustion, stricter emission standards must be established. Additionally, combustion optimization and flue <span class="hlt">gas</span> purification system could be used for lowering NO X emissions from <span class="hlt">gas</span>-fired combustion, and <span class="hlt">gas</span>-fired facilities should be continuously monitored based on emission limits. Graphical abstract Spatial distribution and typical live photos of <span class="hlt">gas</span>-fired boiler in Beijing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27960607','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27960607"><span>Evaluation of <span class="hlt">air</span> quality zone classification methods based on ambient <span class="hlt">air</span> <span class="hlt">concentration</span> exposure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Freeman, Brian; McBean, Ed; Gharabaghi, Bahram; Thé, Jesse</p> <p>2017-05-01</p> <p><span class="hlt">Air</span> quality zones are used by regulatory authorities to implement ambient <span class="hlt">air</span> standards in order to protect human health. <span class="hlt">Air</span> quality measurements at discrete <span class="hlt">air</span> monitoring stations are critical tools to determine whether an <span class="hlt">air</span> quality zone complies with local <span class="hlt">air</span> quality standards or is noncompliant. This study presents a novel approach for evaluation of <span class="hlt">air</span> quality zone classification methods by breaking the <span class="hlt">concentration</span> distribution of a pollutant measured at an <span class="hlt">air</span> monitoring station into compliance and exceedance probability density functions (PDFs) and then using Monte Carlo analysis with the Central Limit Theorem to estimate long-term exposure. The purpose of this paper is to compare the risk associated with selecting one ambient <span class="hlt">air</span> classification approach over another by testing the possible exposure an individual living within a zone may face. The chronic daily intake (CDI) is utilized to compare different pollutant exposures over the classification duration of 3 years between two classification methods. Historical data collected from <span class="hlt">air</span> monitoring stations in Kuwait are used to build representative models of 1-hr NO 2 and 8-hr O 3 within a zone that meets the compliance requirements of each method. The first method, the "3 Strike" method, is a conservative approach based on a winner-take-all approach common with most compliance classification methods, while the second, the 99% Rule method, allows for more robust analyses and incorporates long-term trends. A Monte Carlo analysis is used to model the CDI for each pollutant and each method with the zone at a single station and with multiple stations. The model assumes that the zone is already in compliance with <span class="hlt">air</span> quality standards over the 3 years under the different classification methodologies. The model shows that while the CDI of the two methods differs by 2.7% over the exposure period for the single station case, the large number of samples taken over the duration period impacts the sensitivity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050139794','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050139794"><span>Effects of the Deregulation on the <span class="hlt">Concentration</span> of the Brazilian <span class="hlt">Air</span> Transportation Industry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Guterres, Marcelo Xavier; Muller, Carlos</p> <p>2003-01-01</p> <p>This paper addresses the effects of the deregulation of the Brazilian <span class="hlt">air</span> transportation industry in terms of the <span class="hlt">concentration</span> of the market. We will show some metrics that are commonly used to study the <span class="hlt">concentration</span> of the industry. This paper uses the Herfindhal- Hirschman Index. This index tends to zero in the competitive scenario, with a large number of small firms, and to one in case of a monopolistic scenario. The paper analyses the dynamics of the <span class="hlt">concentration</span> of the Brazilian domestic <span class="hlt">air</span> transportation market, in order to evaluate the effects of deregulation. We conclude that the Brazilian market presents oligopoly characteristics and aspects in its current structure that maintain the market <span class="hlt">concentrated</span> in spite of the Deregulation measures adopted by the aeronautical authority. Keywords: Herfindhal-Hirschman Index, <span class="hlt">concentration</span>, Deregulation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6853185','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6853185"><span>Portable instrument and method for detecting reduced sulfur compounds in a <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Gaffney, J.S.; Kelly, T.J.; Tanner, R.L.</p> <p>1983-06-01</p> <p>A portable real time instrument for detecting <span class="hlt">concentrations</span> in the part per billion range of reduced sulfur compounds in a sample <span class="hlt">gas</span>. Ozonized <span class="hlt">air</span> or oxygen and reduced sulfur compounds in a sample <span class="hlt">gas</span> stream react to produce chemiluminescence in a reaction chamber and the emitted light is filtered and observed by a photomultiplier to detect reduced sulfur compounds. Selective response to individual sulfur compounds is achieved by varying reaction chamber temperature and ozone and sample <span class="hlt">gas</span> flows, and by the use of either <span class="hlt">air</span> or oxygen as the ozone source <span class="hlt">gas</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AtmEn.148..361H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AtmEn.148..361H"><span>The need for harmonization of methods for finding locations and magnitudes of <span class="hlt">air</span> pollution sources using observations of <span class="hlt">concentrations</span> and wind fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hanna, Steven R.; Young, George S.</p> <p>2017-01-01</p> <p>What do the terms "top-down", "inverse", "backwards", "adjoint", "sensor data fusion", "receptor", "source term estimation (STE)", to name several appearing in the current literature, have in common? These varied terms are used by different disciplines to describe the same general methodology - the use of observations of <span class="hlt">air</span> pollutant <span class="hlt">concentrations</span> and knowledge of wind fields to identify <span class="hlt">air</span> pollutant source locations and/or magnitudes. Academic journals are publishing increasing numbers of papers on this topic. Examples of scenarios related to this growing interest, ordered from small scale to large scale, are: use of real-time samplers to quickly estimate the location of a toxic <span class="hlt">gas</span> release by a terrorist at a large public gathering (e.g., Haupt et al., 2009);</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6028440-gonzaga-desulfurization-flue-gas-process','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6028440-gonzaga-desulfurization-flue-gas-process"><span>The Gonzaga desulfurization flue <span class="hlt">gas</span> process</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kelleher, R.L.; O'Leary, T.J.; Shirk, I.A.</p> <p>1984-01-01</p> <p>The Gonzaga desulfurization flue <span class="hlt">gas</span> process removes sulfur dioxide from a flue by cold water scrubbing. Sulfur dioxide is significantly more soluable in cold water (35/sup 0/F to 60/sup 0/F) than in warm water (100/sup 0/F). Sulfur dioxide reacts in water similarly as carbon dioxide reacts in water, in that both gasses are released from the water as the temperature of the water increases. The researchers at the Gonzaga University developed this process from the observations and techniques used in studying the acid and aldehyde <span class="hlt">concentrations</span> in flue gasses with varying of fuel to <span class="hlt">air</span> ratios. The apparatus was fixedmore » to a stationary engine and a <span class="hlt">gas</span>/oil fired boiler. The flue <span class="hlt">gas</span> was cooled to the dew point temperature of the <span class="hlt">air</span> entering the combustion chamber on the pre-<span class="hlt">air</span> heater. The system is described in two parts: the energies required for cooling in the scrubbing section and the energies required in the treatment section. The cold flue <span class="hlt">gas</span> is utilized in cooling the scrubber section.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70014314','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70014314"><span><span class="hlt">Gas</span> bubbles in fossil amber as possible indicators of the major <span class="hlt">gas</span> composition of ancient <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Berner, R.A.; Landis, G.P.</p> <p>1988-01-01</p> <p>Gases trapped in Miocene to Upper Cretaceous amber were released by gently crushing the amber under vacuum and were analyzed by quadrupole mass spectrometry. After discounting the possibility that the major gases N2, O2, and CO2 underwent appreciable diffusion and diagenetic exchange with their surroundings or reaction with the amber, it has been concluded that in primary bubbles (<span class="hlt">gas</span> released during initial breakage) these gases represent mainly original ancient <span class="hlt">air</span> modified by the aerobic respiration of microorganisms. Values of N2/(CO2+O2) for each time period give consistent results despite varying O2/CO2 ratios that presumably were due to varying degrees of respiration. This allows calculation of original oxygen <span class="hlt">concentrations</span>, which, on the basis of these preliminary results, appear to have changed from greater than 30 percent O2 during one part ofthe Late Cretaceous (between 75 and 95 million years ago) to 21 percent during the Eocene-Oligocene and for present-day samples, with possibly lower values during the Oligocene-Early Miocene. Variable O2 levels over time in general confirm theoretical isotope-mass balance calculations and suggest that the atmosphere has evolved over Phanerozoic time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhFl...29d5107S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhFl...29d5107S"><span>Surface velocity divergence model of <span class="hlt">air</span>/water interfacial <span class="hlt">gas</span> transfer in open-channel flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanjou, M.; Nezu, I.; Okamoto, T.</p> <p>2017-04-01</p> <p><span class="hlt">Air</span>/water interfacial <span class="hlt">gas</span> transfer through a free surface plays a significant role in preserving and restoring water quality in creeks and rivers. However, direct measurements of the <span class="hlt">gas</span> transfer velocity and reaeration coefficient are still difficult, and therefore a reliable prediction model needs to be developed. Varying systematically the bulk-mean velocity and water depth, laboratory flume experiments were conducted and we measured surface velocities and dissolved oxygen (DO) <span class="hlt">concentrations</span> in open-channel flows to reveal the relationship between DO transfer velocity and surface divergence (SD). Horizontal particle image velocimetry measurements provide the time-variations of surface velocity divergence. Positive and negative regions of surface velocity divergence are transferred downstream in time, as occurs in boil phenomenon on natural river free-surfaces. The result implies that interfacial <span class="hlt">gas</span> transfer is related to bottom-situated turbulence motion and vertical mass transfer. The original SD model focuses mainly on small-scale viscous motion, and this model strongly depends on the water depth. Therefore, we modify the SD model theoretically to accommodate the effects of the water depth on <span class="hlt">gas</span> transfer, introducing a non-dimensional parameter that includes contributions of depth-scale large-vortex motion, such as secondary currents, to surface renewal events related to DO transport. The modified SD model proved effective and reasonable without any dependence on the bulk mean velocity and water depth, and has a larger coefficient of determination than the original SD model. Furthermore, modeling of friction velocity with the Reynolds number improves the practicality of a new formula that is expected to be used in studies of natural rivers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFDL20011S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFDL20011S"><span>Boundary layers at a dynamic interface: <span class="hlt">air</span>-sea exchange of heat and mass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Szeri, Andrew</p> <p>2017-11-01</p> <p>Exchange of mass or heat across a turbulent liquid-<span class="hlt">gas</span> interface is a problem of critical interest, especially in <span class="hlt">air</span>-sea transfer of natural and man-made gases involved in climate change. The goal in this research area is to determine the <span class="hlt">gas</span> flux from <span class="hlt">air</span> to sea or vice versa. For sparingly soluble non-reactive gases, this is controlled by liquid phase turbulent velocity fluctuations that act on the thin species <span class="hlt">concentration</span> boundary layer on the liquid side of the interface. If the fluctuations in surface-normal velocity and <span class="hlt">gas</span> <span class="hlt">concentration</span> differences are known, then it is possible to determine the turbulent contribution to the <span class="hlt">gas</span> flux. However, there is no suitable fundamental direct approach in the general case where neither of these quantities can be easily measured. A new approach is presented to deduce key aspects about the near-surface turbulent motions from remote measurements, which allows one to determine the <span class="hlt">gas</span> transfer velocity, or <span class="hlt">gas</span> flux per unit area if overall <span class="hlt">concentration</span> differences are known. The approach is illustrated with conceptual examples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A23B2320W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A23B2320W"><span>Roles of Meteorology in Changes of <span class="hlt">Air</span> Pollutants <span class="hlt">Concentrations</span> in China from 2010 to 2015</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, P.; Kota, S. H.; Hu, J.; Ying, Q.; Zhang, H.</p> <p>2017-12-01</p> <p>Tremendous efforts have been made to control the severe <span class="hlt">air</span> pollution in China in recent years. However, no significant improvement was observed according to annual fine particulate matter (PM2.5) <span class="hlt">concentrations</span> and the <span class="hlt">concentrations</span> in severe <span class="hlt">air</span> pollution events in winter. This is partially due to the role of meteorology, which affects the emission, transport, transformation, and deposition of <span class="hlt">air</span> pollutants. In this study, simulation of <span class="hlt">air</span> pollutants over China was conducted for six years from 2010 to 2015 with constant anthropogenic emissions to verify the changes of <span class="hlt">air</span> pollutants due to meteorology changes only. Model performance was validated by comparing with meteorological observations and <span class="hlt">air</span> pollutants measures from various sources. Four different regions/cities were selected to understand the changes in wind, mixing layer height, temperature, and relative humanity at different seasons. The changes in <span class="hlt">concentrations</span> of pollutants including PM2.5 and its chemical components and ozone were analyzed and associated with meteorological changes. This study would provide information for designing effective control strategies in different areas with the consideration of meteorological and climate changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1435769','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1435769"><span>Staged fuel and <span class="hlt">air</span> injection in combustion systems of <span class="hlt">gas</span> turbines</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hughes, Michael John; Berry, Jonathan Dwight</p> <p></p> <p>A <span class="hlt">gas</span> turbine that includes a working fluid flowpath extending aftward from a forward injector in a combustor. The combustor may include an inner radial wall, an outer radial wall, and, therebetween, a flow annulus. A staged injector may intersect the flow annulus so to attain an injection point within the working fluid flowpath by which aftward and forward annulus sections are defined. <span class="hlt">Air</span> directing structure may include an aftward intake section that corresponds to the aftward annulus section and a forward intake section that corresponds to the forward annulus section. The <span class="hlt">air</span> directing structure may be configured to: directmore » <span class="hlt">air</span> entering through the aftward intake section through the aftward annulus section in a forward direction to the staged injector; and direct <span class="hlt">air</span> entering through the forward intake section through the forward annulus section in a forward direction to the forward injector.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1444109','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1444109"><span>Staged fuel and <span class="hlt">air</span> injection in combustion systems of <span class="hlt">gas</span> turbines</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hughes, Michael John; Berry, Jonathan Dwight</p> <p></p> <p>A <span class="hlt">gas</span> turbine that includes a working fluid flowpath extending aftward from a forward injector in a combustor. The combustor may include an inner radial wall, an outer radial wall, and, therebetween, a flow annulus. A staged injector may intersect the flow annulus so to attain an injection point within the working fluid flowpath by which aftward and forward annulus sections are defined. <span class="hlt">Air</span> directing structure may include an aftward intake section that corresponds to the aftward annulus section and a forward intake section that corresponds to the forward annulus section. The <span class="hlt">air</span> directing structure may be configured to: directmore » <span class="hlt">air</span> entering through the aftward intake section through the aftward annulus section in a forward direction to the staged injector; and direct <span class="hlt">air</span> entering through the forward intake section through the forward annulus section in an aftward direction to the staged injector.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770060745&hterms=methane+gas+used&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmethane%2Bgas%2Bused','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770060745&hterms=methane+gas+used&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmethane%2Bgas%2Bused"><span>Exhaust <span class="hlt">gas</span> emissions of a vortex breakdown stabilized combustor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yetter, R. A.; Gouldin, F. C.</p> <p>1976-01-01</p> <p>Exhaust <span class="hlt">gas</span> emission data are described for a swirl stabilized continuous combustor. The combustor consists of confined <span class="hlt">concentric</span> jets with premixed fuel and <span class="hlt">air</span> in the inner jet and <span class="hlt">air</span> in the outer jet. Swirl may be induced in both inner and outer jets with the sense of rotation in the same or opposite directions (co-swirl and counter-swirl). The combustor limits NO emissions by lean operation without sacrificing CO and unburned hydrocarbon emission performance, when commercial-grade methane and <span class="hlt">air</span> fired at one atmosphere without preheat are used. Relative swirl direction and magnitude are found to have significant effects on exhaust <span class="hlt">gas</span> <span class="hlt">concentrations</span>, exit temperatures, and combustor efficiencies. Counter-swirl gives a large recirculation zone, a short luminous combustion zone, and large slip velocities in the interjet shear layer. For maximum counter-swirl conditions, the efficiency is low.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/442124','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/442124"><span>Linear <span class="hlt">air</span>-fuel sensor development</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Garzon, F.; Miller, C.</p> <p>1996-12-14</p> <p>The electrochemical zirconia solid electrolyte oxygen sensor, is extensively used for monitoring oxygen <span class="hlt">concentrations</span> in various fields. They are currently utilized in automobiles to monitor the exhaust <span class="hlt">gas</span> composition and control the <span class="hlt">air</span>-to-fuel ratio, thus reducing harmful emission components and improving fuel economy. Zirconia oxygen sensors, are divided into two classes of devices: (1) potentiometric or logarithmic <span class="hlt">air</span>/fuel sensors; and (2) amperometric or linear <span class="hlt">air</span>/fuel sensors. The potentiometric sensors are ideally suited to monitor the <span class="hlt">air</span>-to-fuel ratio close to the complete combustion stoichiometry; a value of about 14.8 to 1 parts by volume. This occurs because the oxygen <span class="hlt">concentration</span> changesmore » by many orders of magnitude as the <span class="hlt">air</span>/fuel ratio is varied through the stoichiometric value. However, the potentiometric sensor is not very sensitive to changes in oxygen partial pressure away from the stoichiometric point due to the logarithmic dependence of the output voltage signal on the oxygen partial pressure. It is often advantageous to operate gasoline power piston engines with excess combustion <span class="hlt">air</span>; this improves fuel economy and reduces hydrocarbon emissions. To maintain stable combustion away from stoichiometry, and enable engines to operate in the excess oxygen (lean burn) region several limiting-current amperometric sensors have been reported. These sensors are based on the electrochemical oxygen ion pumping of a zirconia electrolyte. They typically show reproducible limiting current plateaus with an applied voltage caused by the <span class="hlt">gas</span> diffusion overpotential at the cathode.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5059628','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5059628"><span>Assessment of regional <span class="hlt">air</span> quality by a <span class="hlt">concentration</span>-dependent Pollution Permeation Index</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Liang, Chun-Sheng; Liu, Huan; He, Ke-Bin; Ma, Yong-Liang</p> <p>2016-01-01</p> <p>Although <span class="hlt">air</span> quality monitoring networks have been greatly improved, interpreting their expanding data in both simple and efficient ways remains challenging. Therefore, needed are new analytical methods. We developed such a method based on the comparison of pollutant <span class="hlt">concentrations</span> between target and circum areas (circum comparison for short), and tested its applications by assessing the <span class="hlt">air</span> pollution in Jing-Jin-Ji, Yangtze River Delta, Pearl River Delta and Cheng-Yu, China during 2015. We found the circum comparison can instantly judge whether a city is a pollution permeation donor or a pollution permeation receptor by a Pollution Permeation Index (PPI). Furthermore, a PPI-related estimated <span class="hlt">concentration</span> (original <span class="hlt">concentration</span> plus halved average <span class="hlt">concentration</span> difference) can be used to identify some overestimations and underestimations. Besides, it can help explain pollution process (e.g., Beijing’s PM2.5 maybe largely promoted by non-local SO2) though not aiming at it. Moreover, it is applicable to any region, easy-to-handle, and able to boost more new analytical methods. These advantages, despite its disadvantages in considering the whole process jointly influenced by complex physical and chemical factors, demonstrate that the PPI based circum comparison can be efficiently used in assessing <span class="hlt">air</span> pollution by yielding instructive results, without the absolute need for complex operations. PMID:27731344</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDH39005G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDH39005G"><span>Quantifying real-<span class="hlt">gas</span> effects on a laminar n-dodecane - <span class="hlt">air</span> premixed flame</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gopal, Abishek; Yellapantula, Shashank; Larsson, Johan</p> <p>2015-11-01</p> <p>With the increasing demand for higher efficiencies in aircraft <span class="hlt">gas</span>-turbine engines, there has been a progressive march towards high pressure-ratio cycles. Under these conditions, the aviation fuel, Jet A, is injected into the combustor at supercritical pressures. In this work, we study and quantify the effects of transcriticality on a 1D freely propagating laminar n-dodecane - <span class="hlt">air</span> premixed flame. The impact of the constitutive state relations arising from the Ideal <span class="hlt">Gas</span> equation of state(EOS) and Peng-Robinson EOS on flame structure and propagation is presented. The effects of real-<span class="hlt">gas</span> models of transport properties, such as viscosity on laminar flame speed, are also presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.2132J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.2132J"><span><span class="hlt">Concentrations</span> of Reactive Trace Gases In The Interstitial <span class="hlt">Air</span> of Surface Snow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jacobi, H.-W.; Honrath, R. E.; Peterson, M. C.; Lu, Y.; Dibb, J. E.; Arsenault, M. A.; Swanson, A. L.; Blake, N. J.; Bales, R. C.; Schrems, O.</p> <p></p> <p>Several measurements at Arctic and Antarctic sites have demonstrated that unexpected photochemical reactions occur in irradiated surface snow influencing the composi- tion of the boundary layer over snow-covered areas. The results of these reactions are probably most obvious in the interstitial <span class="hlt">air</span> of the surface snow since it constitutes the interface between the surface snow and the boundary layer. Therefore, measurements of <span class="hlt">concentrations</span> of nitrogen oxide and dioxide, nitrous acid, formaldehyde, hydro- gen peroxide, formic acid, acetic acid, and other organic compounds were performed in the interstitial <span class="hlt">air</span> of the surface snow of the Greenland ice sheet. <span class="hlt">Concentrations</span> were measured at variable depths between - 10 cm and - 50 cm during the summer field season in 2000 at the Summit Environmental Observatory. At shallow depths, the system NO-NO2-O3 exhibits large deviations from the calculated photostationary state. Using steady-state analyses applied to OH-HO2-CH3O2 cycling indicated the presence of high <span class="hlt">concentrations</span> of OH and peroxy radicals in the firn <span class="hlt">air</span>. Maximum <span class="hlt">concentrations</span> calculated for a depth of - 10 cm are in the order of 6 105 molecules cm-3 and 1.4 * 107 molecules cm-3 for OH and HO2, respectively, although radia- tion levels at - 10 cm are reduced by approximately 50 % compared to levels above the snow surface. By far the most important OH source is the photolysis of HONO while the photolysis of ozone contributes less than 2 % to the overall production of OH in the firn <span class="hlt">air</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AtmEn.133...60J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AtmEn.133...60J"><span>Size distribution and <span class="hlt">concentration</span> of soot generated in oil and <span class="hlt">gas</span>-fired residential boilers under different combustion conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiménez, Santiago; Barroso, Jorge; Pina, Antonio; Ballester, Javier</p> <p>2016-05-01</p> <p>In spite of the relevance of residential heating burners in the global emission of soot particles to the atmosphere, relatively little information on their properties (<span class="hlt">concentration</span>, size distribution) is available in the literature, and even less regarding the dependence of those properties on the operating conditions. Instead, the usual procedure to characterize those emissions is to measure the smoke opacity by several methods, among which the blackening of a paper after filtering a fixed amount of <span class="hlt">gas</span> (Bacharach test) is predominant. In this work, the size distributions of the particles generated in the combustion of a variety of gaseous and liquid fuels in a laboratory facility equipped with commercial burners have been measured with a size classifier coupled to a particle counter in a broad range of operating conditions (<span class="hlt">air</span> excesses), with simultaneous determination of the Bacharach index. The shape and evolution of the distribution with progressively smaller oxygen <span class="hlt">concentrations</span> depends essentially on the state of the fuel: whereas the combustion of the gases results in monomodal distributions that 'shift' towards larger diameters, in the case of the <span class="hlt">gas</span>-oils an ultrafine mode is always observed, and a secondary mode of coarse particle grows in relevance. In both cases, there is a strong, exponential correlation between the total mass <span class="hlt">concentration</span> and the Bacharach opacity index, quite similar for both groups of fuels. The empirical expressions proposed may allow other researchers to at least estimate the emissions of numerous combustion facilities routinely characterized by their smoke opacities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20526768','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20526768"><span>Highly sensitive determination of polycyclic aromatic hydrocarbons in ambient <span class="hlt">air</span> dust by <span class="hlt">gas</span> chromatography-mass spectrometry after molecularly imprinted polymer extraction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Krupadam, Reddithota J; Bhagat, Bhagyashree; Khan, Muntazir S</p> <p>2010-08-01</p> <p>A method based on solid--phase extraction with a molecularly imprinted polymer (MIP) has been developed to determine five probable human carcinogenic polycyclic aromatic hydrocarbons (PAHs) in ambient <span class="hlt">air</span> dust by <span class="hlt">gas</span> chromatography-mass spectrometry (GC-MS). Molecularly imprinted poly(vinylpyridine-co-ethylene glycol dimethacrylate) was chosen as solid-phase extraction (SPE) material for PAHs. The conditions affecting extraction efficiency, for example surface properties, <span class="hlt">concentration</span> of PAHs, and equilibration times were evaluated and optimized. Under optimum conditions, pre-<span class="hlt">concentration</span> factors for MIP-SPE ranged between 80 and 93 for 10 mL ambient <span class="hlt">air</span> dust leachate. PAHs recoveries from MIP-SPE after extraction from <span class="hlt">air</span> dust were between 85% and 97% and calibration graphs of the PAHs showed a good linearity between 10 and 1000 ng L(-1) (r = 0.99). The extraction efficiency of MIP for PAHs was compared with that of commercially available SPE materials--powdered activated carbon (PAC) and polystyrene-divinylbenzene resin (XAD)--and it was shown that the extraction capacity of the MIP was better than that of the other two SPE materials. Organic matter in <span class="hlt">air</span> dust had no effect on MIP extraction, which produced a clean extract for GC-MS analysis. The detection limit of the method proposed in this article is 0.15 ng L(-1) for benzo[a]pyrene, which is a marker molecule of <span class="hlt">air</span> pollution. The method has been applied to the determination of probable carcinogenic PAHs in <span class="hlt">air</span> dust of industrial zones and satisfactory results were obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/549561-research-acting-mechanism-behavior-gas-bubble-air-dense-medium-fluidized-bed','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/549561-research-acting-mechanism-behavior-gas-bubble-air-dense-medium-fluidized-bed"><span>Research on acting mechanism and behavior of a <span class="hlt">gas</span> bubble in the <span class="hlt">air</span> dense medium fluidized bed</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Tao, X.; Chen, Q.; Yang, Y.</p> <p>1996-12-31</p> <p>Coal dry beneficiation with <span class="hlt">air</span>-dense medium fluidized bed has now been established as a high efficiency dry separation technology, it is the application of fluidization technology to the coal preparation field. The tiny particle media forms an uniform and stable fluidized bed with a density acted by airflow, which is used to separate 80{micro}m to {approximately}6mm size coal. This technology has achieved satisfied industrialization results, and attracted the expert`s attention in the field. In fluidized bed, the interaction between <span class="hlt">gas</span> and solid was mainly decided by the existence state of heavy media particles mass (position and distance) relative velocity ofmore » <span class="hlt">gas</span>-solid two phase, as well turbulent action. A change of vertical <span class="hlt">gas</span>-solid fluidizing state essentially is the one of a energy transforming process. For a coal separating process with <span class="hlt">air</span>-dense medium fluidized bed, the <span class="hlt">gas</span> bubble, producing a turbulent and stirring action in the bed, leads to two effects. It can promote a uniform distribution of heavy media particles, and a uniform and stability of a bed density. Otherwise it will decrease effective contacts between <span class="hlt">gas</span>-solids two phases, producing a bigger <span class="hlt">gas</span> bubble. Therefore controlling a <span class="hlt">gas</span> bubble size in bed should be optimized. This paper analyzes mutual movement between <span class="hlt">gas</span>-solid, and studies the <span class="hlt">gas</span> bubble behavior in the bed. A mechanic mode and a separating process of coal in the bed is discussed. It aims to research the coal separating mechanism with <span class="hlt">air</span>-dense fluidized bed.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29671775','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29671775"><span>A Fast and Easily-Realized <span class="hlt">Concentration</span> Sensor for Binary <span class="hlt">Gas</span> Mixtures and Its Design Analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guan, Yu; Lu, Song; Zhang, Dan; Hu, Yang; Yuan, Wei</p> <p>2018-04-19</p> <p>A low-cost and easily-realized sensing device used for the detection of <span class="hlt">gas</span> mixtures at different <span class="hlt">concentrations</span> is presented. Its sensing part includes a small critical nozzle, a laminar structure, and a differential pressure sensor. When <span class="hlt">gas</span> flows through the laminar structure, there is a pressure drop between both ends of it, and for different components of <span class="hlt">gas</span>, the pressure drop is different. Based on this feature, the <span class="hlt">concentration</span> detection is achieved. <span class="hlt">Concentration</span> tests for two types of fire extinguishing agents CBrF₃ and C₃HF₇ are presented. The results show the characteristics of fast response/recovery time, high accuracy, and good repeatability. Based on the theoretical analysis, the effects of the design parameters on the sensing performance to <span class="hlt">concentration</span> detection are discussed in detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5319244','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/5319244"><span><span class="hlt">Air</span> ejector augmented compressed <span class="hlt">air</span> energy storage system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ahrens, F.W.; Kartsounes, G.T.</p> <p></p> <p>Energy is stored in slack demand periods by charging a plurality of underground reservoirs with <span class="hlt">air</span> to the same peak storage pressure, during peak demand periods throttling the <span class="hlt">air</span> from one storage reservoir into a <span class="hlt">gas</span> turbine system at a constant inlet pressure until the <span class="hlt">air</span> presure in the reservoir falls to said constant inlet pressure, thereupon permitting <span class="hlt">air</span> in a second reservoir to flow into said <span class="hlt">gas</span> turbine system while drawing <span class="hlt">air</span> from the first reservoir through a variable geometry <span class="hlt">air</span> ejector and adjusting said variable geometry <span class="hlt">air</span> ejector, said <span class="hlt">air</span> flow being essentially at the constant inlet pressure of the <span class="hlt">gas</span> turbine system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/863741','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/863741"><span><span class="hlt">Air</span> ejector augmented compressed <span class="hlt">air</span> energy storage system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ahrens, Frederick W.; Kartsounes, George T.</p> <p>1980-01-01</p> <p>Energy is stored in slack demand periods by charging a plurality of underground reservoirs with <span class="hlt">air</span> to the same peak storage pressure, during peak demand periods throttling the <span class="hlt">air</span> from one storage reservoir into a <span class="hlt">gas</span> turbine system at a constant inlet pressure until the <span class="hlt">air</span> pressure in the reservoir falls to said constant inlet pressure, thereupon permitting <span class="hlt">air</span> in a second reservoir to flow into said <span class="hlt">gas</span> turbine system while drawing <span class="hlt">air</span> from the first reservoir through a variable geometry <span class="hlt">air</span> ejector and adjusting said variable geometry <span class="hlt">air</span> ejector, said <span class="hlt">air</span> flow being essentially at the constant inlet pressure of the <span class="hlt">gas</span> turbine system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=223609&keyword=water+AND+gas+AND+exchange&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=223609&keyword=water+AND+gas+AND+exchange&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span><span class="hlt">Air</span>-water <span class="hlt">Gas</span> Exchange Rates on a Large Impounded River Measured Using Floating Domes (Poster)</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Mass balance models of dissolved gases in rivers typically serve as the basis for whole-system estimates of greenhouse <span class="hlt">gas</span> emission rates. An important component of these models is the exchange of dissolved gases between <span class="hlt">air</span> and water. Controls on <span class="hlt">gas</span> exchange rates (K) have be...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2860091','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2860091"><span>Particle-phase <span class="hlt">concentrations</span> of polycyclic aromatic hydrocarbons in ambient <span class="hlt">air</span> of rural residential areas in southern Germany</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Baumbach, Günter; Kuch, Bertram; Scheffknecht, Günter</p> <p>2010-01-01</p> <p>An important source of polycyclic aromatic hydrocarbons (PAHs) in residential areas, particularly in the winter season, is the burning process when wood is used for domestic heating. The target of this study was to investigate the particle-phase PAH composition of ambient samples in order to assess the influence of wood combustion on <span class="hlt">air</span> quality in residential areas. PM10 samples (particulate matter <10 μm) were collected during two winter seasons at two rural residential areas near Stuttgart in Germany. Samples were extracted using toluene in an ultrasonic bath and subsequently analysed by <span class="hlt">gas</span> chromatography–mass spectrometry. Twenty-one PAH compounds were detected and quantified. The PAH fingerprints of different wood combustion emissions were found in significant amounts in ambient samples and high correlations between total PAHs and other wood smoke tracers were found, indicating the dominant influence of wood combustion on <span class="hlt">air</span> quality in residential areas. Carcinogenic PAHs were detected in high <span class="hlt">concentrations</span> and contributed 49% of the total PAHs in the ambient <span class="hlt">air</span>. To assess the health risk, we investigated the exposure profile of individual PAHs. The findings suggest that attention should be focused on using the best combustion technology available to reduce emissions from wood-fired heating during the winter in residential areas. PMID:20495599</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017HMT...tmp..463D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017HMT...tmp..463D"><span>Parametric study of a <span class="hlt">concentric</span> coaxial glass tube solar <span class="hlt">air</span> collector: a theoretical approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dabra, Vishal; Yadav, Avadhesh</p> <p>2017-12-01</p> <p><span class="hlt">Concentric</span> coaxial glass tube solar <span class="hlt">air</span> collector (CCGTSAC) is a quite innovative development in the field of solar collectors. This type of collector is specially designed to produce hot <span class="hlt">air</span>. A mathematical model based on the energy conservation equations for small control volumes along the axial direction of <span class="hlt">concentric</span> coaxial glass tube (CCGT) is developed in this paper. It is applied to predict the effect of thirteen different parameters on the exit <span class="hlt">air</span> temperature rise and appeared that absorber tube size, length of CCGT, absorptivity of transparent glazing, transmissivity of transparent glazing, absorptivity of absorber coating, inlet or ambient <span class="hlt">air</span> temperature, mass flow rate, variation of thermo-physical properties of <span class="hlt">air</span>, wind speed, solar intensity and vacuum present between transparent glazing and absorber tube are significant parameters. Results of the model were analysed to predict the effect of key parameters on the thermal performance of a CCGTSAC for exit <span class="hlt">air</span> temperature rise about 43.9-58.4 °C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018HMT....54.1613D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018HMT....54.1613D"><span>Parametric study of a <span class="hlt">concentric</span> coaxial glass tube solar <span class="hlt">air</span> collector: a theoretical approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dabra, Vishal; Yadav, Avadhesh</p> <p>2018-06-01</p> <p><span class="hlt">Concentric</span> coaxial glass tube solar <span class="hlt">air</span> collector (CCGTSAC) is a quite innovative development in the field of solar collectors. This type of collector is specially designed to produce hot <span class="hlt">air</span>. A mathematical model based on the energy conservation equations for small control volumes along the axial direction of <span class="hlt">concentric</span> coaxial glass tube (CCGT) is developed in this paper. It is applied to predict the effect of thirteen different parameters on the exit <span class="hlt">air</span> temperature rise and appeared that absorber tube size, length of CCGT, absorptivity of transparent glazing, transmissivity of transparent glazing, absorptivity of absorber coating, inlet or ambient <span class="hlt">air</span> temperature, mass flow rate, variation of thermo-physical properties of <span class="hlt">air</span>, wind speed, solar intensity and vacuum present between transparent glazing and absorber tube are significant parameters. Results of the model were analysed to predict the effect of key parameters on the thermal performance of a CCGTSAC for exit <span class="hlt">air</span> temperature rise about 43.9-58.4 °C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27130121','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27130121"><span>Dopant-assisted negative photoionization Ion mobility spectrometry coupled with on-line cooling inlet for real-time monitoring H2S <span class="hlt">concentration</span> in sewer <span class="hlt">gas</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peng, Liying; Jiang, Dandan; Wang, Zhenxin; Hua, Lei; Li, Haiyang</p> <p>2016-06-01</p> <p>Malodorous hydrogen sulfide (H2S) <span class="hlt">gas</span> often exists in the sewer system and associates with the problems of releasing the dangerous odor to the atmosphere and causing sewer pipe to be corroded. A simple method is in demand for real-time measuring H2S level in the sewer <span class="hlt">gas</span>. In this paper, an innovated method based on dopant-assisted negative photoionization ion mobility spectrometry (DANP-IMS) with on-line semiconductor cooling inlet was put forward and successfully applied for the real-time measurement of H2S in sewer <span class="hlt">gas</span>. The influence of moisture was effectively reduced via an on-line cooling method and a non-equilibrium dilution with drift <span class="hlt">gas</span>. The limits of quantitation for the H2S in ≥60% relative humidity <span class="hlt">air</span> could be obtained at ≤79.0ng L(-1) with linear ranges of 129-2064ng L(-1). The H2S <span class="hlt">concentration</span> in a sewer manhole was successfully determined while its product ions were identified by an ion-mobility time-of-fight mass spectrometry. Finally, the correlation between sewer H2S <span class="hlt">concentration</span> and the daily routines and habits of residents was investigated through hourly or real-time monitoring the variation of sewer H2S in manholes, indicating the power of this DANP-IMS method in assessing the H2S <span class="hlt">concentration</span> in sewer system. Copyright © 2016 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ThEng..63..529M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ThEng..63..529M"><span>Problems in creation of modern <span class="hlt">air</span> inlet filters of power <span class="hlt">gas</span> turbine plants in Russia and methods of their solving</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mikhaylov, V. E.; Khomenok, L. A.; Sherapov, V. V.</p> <p>2016-08-01</p> <p>The main problems in creation and operation of modern <span class="hlt">air</span> inlet paths of <span class="hlt">gas</span> turbine plants installed as part of combined-cycle plants in Russia are presented. It is noted that design features of <span class="hlt">air</span> inlet filters shall be formed at the stage of the technical assignment not only considering the requirements of <span class="hlt">gas</span> turbine plant manufacturer but also climatic conditions, local atmospheric <span class="hlt">air</span> dustiness, and a number of other factors. The recommendations on completing of filtration system for <span class="hlt">air</span> inlet filter of power <span class="hlt">gas</span> turbine plants depending on the facility location are given, specific defects in design and experience in operation of imported <span class="hlt">air</span> inlet paths are analyzed, and influence of cycle <span class="hlt">air</span> preparation quality for <span class="hlt">gas</span> turbine plant on value of operating expenses and cost of repair works is noted. <span class="hlt">Air</span> treatment equipment of various manufacturers, influence of aerodynamic characteristics on operation of <span class="hlt">air</span> inlet filters, features of filtration system operation, anti-icing system, weather canopies, and other elements of <span class="hlt">air</span> inlet paths are considered. It is shown that nonuniformity of <span class="hlt">air</span> flow velocity fields in clean <span class="hlt">air</span> chamber has a negative effect on capacity and aerodynamic resistance of <span class="hlt">air</span> inlet filter. Besides, the necessity in installation of a sufficient number of differential pressure transmitters allowing controlling state of each treatment stage not being limited to one measurement of total differential pressure in the filtration system is noted in the article. According to the results of the analysis trends and methods for modernization of available equipment for <span class="hlt">air</span> inlet path, the importance of creation and implementation of new technologies for manufacturing of filtering elements on sites of Russia within the limits of import substitution are given, and measures on reliability improvement and energy efficiency for <span class="hlt">air</span> inlet filter are considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EPJWC..2405004I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EPJWC..2405004I"><span>Time lag between the tropopause height and the levels of 7Be <span class="hlt">concentration</span> in near surface <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ioannidou, A.; Vasileiadis, A.; Melas, D.</p> <p>2012-04-01</p> <p>The <span class="hlt">concentration</span> of 7Be at near surface <span class="hlt">air</span> has been determined over 2009, a year of a deep solar minimum, in the region of Thessaloniki, Greece at 40°62' N, 22°95'E. In geomagnetic latitudes over 40° N, the elevation of the tropopause during the warm summer months and the vertical exchange of <span class="hlt">air</span> masses within the troposphere cause greater mixture of the <span class="hlt">air</span> masses resulting in higher <span class="hlt">concentration</span> levels for 7Be in surface <span class="hlt">air</span>. The positive correlation between the monthly activity <span class="hlt">concentration</span> of 7Be and the tropopause height (0.94, p < 0.0001), and also between 7Be <span class="hlt">concentration</span> and the temperature T (°C) (R = 0.97, p < 0.001), confirm that the increased rate of vertical transport within the troposphere, especially during warmer summer months, has as a result the descent to surface of <span class="hlt">air</span> masses enriched in 7Be. However, the 7Be <span class="hlt">concentration</span> levels in near surface <span class="hlt">air</span> are not expected to respond immediately to the change of elevation of the tropopause. It was found that there's a time lag of ~ 3 days between the change in the daily surface <span class="hlt">concentrations</span> of 7Be the change in the elevation of the tropopause.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22616747','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22616747"><span>Microfabricated <span class="hlt">gas</span> chromatograph for on-site determinations of TCE in indoor <span class="hlt">air</span> arising from vapor intrusion. 2. Spatial/temporal monitoring.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Sun Kyu; Burris, David R; Bryant-Genevier, Jonathan; Gorder, Kyle A; Dettenmaier, Erik M; Zellers, Edward T</p> <p>2012-06-05</p> <p>We demonstrate the use of two prototype Si-microfabricated <span class="hlt">gas</span> chromatographs (μGC) for continuous, short-term measurements of indoor trichloroethylene (TCE) vapor <span class="hlt">concentrations</span> related to the investigation of TCE vapor intrusion (VI) in two houses. In the first house, with documented TCE VI, temporal variations in TCE <span class="hlt">air</span> <span class="hlt">concentrations</span> were monitored continuously for up to 48 h near the primary VI entry location under different levels of induced differential pressure (relative to the subslab). <span class="hlt">Concentrations</span> ranged from 0.23 to 27 ppb by volume (1.2-150 μg/m(3)), and <span class="hlt">concentration</span> trends agreed closely with those determined from concurrent reference samples. The sensitivity and temporal resolution of the measurements were sufficiently high to detect transient fluctuations in <span class="hlt">concentration</span> resulting from short-term changes in variables affecting the extent of VI. Spatial monitoring showed a decreasing TCE <span class="hlt">concentration</span> gradient with increasing distance from the primary VI entry location. In the second house, with no TCE VI, spatial profiles derived from the μGC prototype data revealed an intentionally hidden source of TCE within a closet, demonstrating the capability for locating non-VI sources. <span class="hlt">Concentrations</span> measured in this house ranged from 0.51 to 56 ppb (2.7-300 μg/m(3)), in good agreement with reference method values. This first field demonstration of μGC technology for automated, near-real-time, selective VOC monitoring at low- or subppb levels augurs well for its use in short- and long-term on-site analysis of indoor <span class="hlt">air</span> in support of VI assessments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5334668','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5334668"><span>Prediction of <span class="hlt">Air</span> Pollutants <span class="hlt">Concentration</span> Based on an Extreme Learning Machine: The Case of Hong Kong</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhang, Jiangshe; Ding, Weifu</p> <p>2017-01-01</p> <p>With the development of the economy and society all over the world, most metropolitan cities are experiencing elevated <span class="hlt">concentrations</span> of ground-level <span class="hlt">air</span> pollutants. It is urgent to predict and evaluate the <span class="hlt">concentration</span> of <span class="hlt">air</span> pollutants for some local environmental or health agencies. Feed-forward artificial neural networks have been widely used in the prediction of <span class="hlt">air</span> pollutants <span class="hlt">concentration</span>. However, there are some drawbacks, such as the low convergence rate and the local minimum. The extreme learning machine for single hidden layer feed-forward neural networks tends to provide good generalization performance at an extremely fast learning speed. The major sources of <span class="hlt">air</span> pollutants in Hong Kong are mobile, stationary, and from trans-boundary sources. We propose predicting the <span class="hlt">concentration</span> of <span class="hlt">air</span> pollutants by the use of trained extreme learning machines based on the data obtained from eight <span class="hlt">air</span> quality parameters in two monitoring stations, including Sham Shui Po and Tap Mun in Hong Kong for six years. The experimental results show that our proposed algorithm performs better on the Hong Kong data both quantitatively and qualitatively. Particularly, our algorithm shows better predictive ability, with R2 increased and root mean square error values decreased respectively. PMID:28125034</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.7771C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.7771C"><span>Dissolved <span class="hlt">gas</span> <span class="hlt">concentrations</span> of the geothermal fluids in Taiwan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Ai-Ti; Yang, Tsanyao Frank</p> <p>2010-05-01</p> <p>Taiwan, a geologically active island, is located on the boundary of the Philippine Sea Plate and the Eurasian Plate. High heat flow and geothermal gradient generated by the complex collision and orogeny, warm up the meteoric water and/or the ground water. The heated water becomes geothermal fluids. In previous studies, researchers tried to categorize hot springs based on the appearance, chemical compositions and lithological areas. Because of the chemical inertness, the <span class="hlt">concentrations</span> and isotopic composition of dissolved noble gases are good indicators of the mantle degassing, geothermal conditions, and so on. In this study, 55 hot springs were collected from different tectonic units. It is the first time to systematically study the hot springs in Taiwan in terms of dissolved gases. Hot spring water is sampled and stored in pre-evacuated glass bottles for analyzing <span class="hlt">gas</span> compositions. The abundances of noble gases were determined by a quadrupole mass spectrometer based on the isotope dilution technique. Samples with glass vials are introduced to RAD 7 and GC for dissolved Rn and major dissolved gases analyses. Furthermore, helium isotopic ratios and helium-neon ratios are measured on a conventional noble <span class="hlt">gas</span> mass spectrometer. For hydrochemistry analysis, water samples are analyzed by IC, ICP-MS and titration. We can classify the hot springs samples into three major groups from main anion <span class="hlt">concentration</span> data; and then, subdivide them into nine minor groups by cation <span class="hlt">concentration</span> data. Moreover, according to major dissolved gases compositions, three major <span class="hlt">gas</span> components: CH4, N2 and CO2, are identified. Dissolved noble gases provided more detailed clues about hot springs sources in Taiwan, such as the degree of mixing between meteoric water and deep-source water, which will be further discussed in this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A11M0237V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A11M0237V"><span>Regional Influences of Marcellus Shale Natural <span class="hlt">Gas</span> Activity: Back-trajectory Analysis of Baltimore/Washington Ethane <span class="hlt">Concentrations</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vinciguerra, T.; Chittams, A.; Dadzie, J.; Deskins, T.; Goncalves, V.; M'Bagui Matsanga, C.; Zakaria, R.; Ehrman, S.; Dickerson, R. R.</p> <p>2015-12-01</p> <p>Over the past several years, the combined utilization of hydraulic fracturing and horizontal drilling has led to a rapid increase in natural <span class="hlt">gas</span> production, especially from the Marcellus Shale. To explore the impact of this activity downwind on regions with no natural <span class="hlt">gas</span> production, the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) Model was used to generate 48-hour back-trajectories for summer, daytime hours from the years 2007-2014 in the Baltimore, MD and Washington, D.C. areas where hourly ethane measurements are available from Photochemical Assessment Monitoring Stations (PAMS). For each of the years investigated, unconventional well counts were obtained for counties in the surrounding states of Pennsylvania, Ohio, West Virginia, and Virginia, and counties exceeding a threshold of 0.05 wells/km2 were designated as counties with a high density of wells. The back-trajectories for each year were separated into two groups: those which passed through counties containing a high density of wells, and those which did not. Back-trajectories passing through high-density counties were further screened by applying a height criterion where trajectories beyond 10% above the mixing layer were excluded. Preliminary results indicate that <span class="hlt">air</span> parcels with back-trajectories passing within the boundary layer of counties with a high density of unconventional natural <span class="hlt">gas</span> wells correspond to significantly greater <span class="hlt">concentrations</span> of observed ethane at these downwind monitors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25622867','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25622867"><span>Effects of forage-to-<span class="hlt">concentrate</span> ratio and dietary fiber manipulation on <span class="hlt">gas</span> emissions and olfactometry from manure of Holstein heifers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lascano, G J; Heinrichs, A J; Gary, R R; Topper, P A; Brandt, R C; Adviento-Borbe, A; Fabian, E E</p> <p>2015-03-01</p> <p>The objective of this experiment was to determine the effects of differing ratios of forage to <span class="hlt">concentrate</span> (F:C) and fiber levels on odor and <span class="hlt">gas</span> emissions from manure. Eight Holstein dairy heifers (362.45±4.53 d of age and 335.6±7.41 kg of body weight) were randomly assigned to a split-plot, 4×4 Latin square design (21-d periods) with F:C as the whole plot (20 or 80% forage) and fiber level as sub-plot (0, 20, 40, or 60% inclusion of corn stover). <span class="hlt">Gas</span> <span class="hlt">concentration</span> was determined using an infrared photoacoustic analyzer over a 24-h period using a steady-state flux chamber setup. Odorous <span class="hlt">air</span> samples were collected from chamber headspace and evaluated by 6 human assessors using a forced-choice dynamic olfactometry technique. Emissions of CO2 were greater for the low than high <span class="hlt">concentrate</span> diets, and no differences were observed for NH3 and CH4 emissions between F:C. Although F:C had no effect on NH3 emissions, as dietary fiber increased, a linear interaction with opposite effects was found for high and low <span class="hlt">concentrate</span> diets. Nitrous oxide emissions were below minimum detectable levels. Neither F:C nor neutral detergent fiber level affected odor intensity. Odor emissions were successfully assessed, and manipulation of dietary fiber has the potential to influence CH4 and NH3 emissions. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ACP....16.7485M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ACP....16.7485M"><span>New particle formation in the fresh flue-<span class="hlt">gas</span> plume from a coal-fired power plant: effect of flue-<span class="hlt">gas</span> cleaning</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mylläri, Fanni; Asmi, Eija; Anttila, Tatu; Saukko, Erkka; Vakkari, Ville; Pirjola, Liisa; Hillamo, Risto; Laurila, Tuomas; Häyrinen, Anna; Rautiainen, Jani; Lihavainen, Heikki; O'Connor, Ewan; Niemelä, Ville; Keskinen, Jorma; Dal Maso, Miikka; Rönkkö, Topi</p> <p>2016-06-01</p> <p>Atmospheric emissions, including particle number and size distribution, from a 726 MWth coal-fired power plant were studied experimentally from a power plant stack and flue-<span class="hlt">gas</span> plume dispersing in the atmosphere. Experiments were conducted under two different flue-<span class="hlt">gas</span> cleaning conditions. The results were utilized in a plume dispersion and dilution model taking into account particle formation precursor (H2SO4 resulted from the oxidation of emitted SO2) and assessment related to nucleation rates. The experiments showed that the primary emissions of particles and SO2 were effectively reduced by flue-<span class="hlt">gas</span> desulfurization and fabric filters, especially the emissions of particles smaller than 200 nm in diameter. Primary pollutant <span class="hlt">concentrations</span> reached background levels in 200-300 s. However, the atmospheric measurements indicated that new particles larger than 2.5 nm are formed in the flue-<span class="hlt">gas</span> plume, even in the very early phases of atmospheric ageing. The effective number emission of nucleated particles were several orders of magnitude higher than the primary particle emission. Modelling studies indicate that regardless of continuing dilution of the flue <span class="hlt">gas</span>, nucleation precursor (H2SO4 from SO2 oxidation) <span class="hlt">concentrations</span> remain relatively constant. In addition, results indicate that flue-<span class="hlt">gas</span> nucleation is more efficient than predicted by atmospheric aerosol modelling. In particular, the observation of the new particle formation with rather low flue-<span class="hlt">gas</span> SO2 <span class="hlt">concentrations</span> changes the current understanding of the <span class="hlt">air</span> quality effects of coal combustion. The results can be used to evaluate optimal ways to achieve better <span class="hlt">air</span> quality, particularly in polluted areas like India and China.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7342802-measuring-radon-concentration-air-meting-van-de-radonconcentratie-lucht','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/7342802-measuring-radon-concentration-air-meting-van-de-radonconcentratie-lucht"><span>Measuring the radon <span class="hlt">concentration</span> in <span class="hlt">air</span> meting van de radonconcentratie in lucht</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Aten, J.B.T.; Bierhuizen, H.W.J.; Vanhoek, L.P.</p> <p>1975-01-01</p> <p>A simple transportable apparatus for measurement of the radon <span class="hlt">concentration</span> in the <span class="hlt">air</span> of a workshop was developed. An <span class="hlt">air</span> sample is sucked through a filter and the decay curve of the alpha activity is measured. The counting speed 40 min after sampling gives an indication of the radon activity. The apparatus was calibrated by analyzing an analogous decay curve obtained with a big filter and a big <span class="hlt">air</span> sample, the activity being measured with an anti-coincidence counter. (GRA)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AtmEn..44.2186L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AtmEn..44.2186L"><span><span class="hlt">Air</span> ion <span class="hlt">concentrations</span> in various urban outdoor environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ling, Xuan; Jayaratne, Rohan; Morawska, Lidia</p> <p>2010-06-01</p> <p>Atmospheric ions are produced by many natural and anthropogenic sources and their <span class="hlt">concentrations</span> vary widely between different environments. There is very little information on their <span class="hlt">concentrations</span> in different types of urban environments, how they compare across these environments and their dominant sources. In this study, we measured airborne <span class="hlt">concentrations</span> of small ions, particles and net particle charge at 32 different outdoor sites in and around a major city in Australia and identified the main ion sources. Sites were classified into seven groups as follows: park, woodland, city centre, residential, freeway, power lines and power substation. Generally, parks were situated away from ion sources and represented the urban background value of about 270 ions cm -3. Median <span class="hlt">concentrations</span> at all other groups were significantly higher than in the parks. We show that motor vehicles and power transmission systems are two major ion sources in urban areas. Power lines and substations constituted strong unipolar sources, while motor vehicle exhaust constituted strong bipolar sources. The small ion <span class="hlt">concentration</span> in urban residential areas was about 960 cm -3. At sites where ion sources were co-located with particle sources, ion <span class="hlt">concentrations</span> were inhibited due to the ion-particle attachment process. These results improved our understanding on <span class="hlt">air</span> ion distribution and its interaction with particles in the urban outdoor environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29299669','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29299669"><span><span class="hlt">Air</span>-breathing behavior, oxygen <span class="hlt">concentrations</span>, and ROS defense in the swimbladders of two erythrinid fish, the facultative <span class="hlt">air</span>-breathing jeju, and the non-<span class="hlt">air</span>-breathing traira during normoxia, hypoxia and hyperoxia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pelster, Bernd; Wood, Chris M; Jung, Ellen; Val, Adalberto L</p> <p>2018-05-01</p> <p>The jeju Hoplerythrinus unitaeniatus and the traira Hoplias malabaricus are two neighboring genera from the family of erythrinid fish, both possessing a two-chambered physostomous swimbladder. In the jeju the anterior section of the posterior bladder is highly vascularized, and the swimbladder is used for aerial respiration; the traira, in turn, is a water-breather that uses the swimbladder as a buoyancy organ and not for aerial oxygen uptake. Measurement of swimbladder oxygen partial pressure (PO 2 ) of fish kept at 26 °C in normoxic, hyperoxic (28-32 mg O 2 L - 1 ) or hypoxic (1-1.5 mg O 2 L - 1 ) water revealed constant values in traira swimbladder. Under normoxic conditions in the jeju swimbladder PO 2 was higher than in traira, and the PO 2 significantly increased under hyperoxic conditions, even in the absence of <span class="hlt">air</span> breathing. In jeju, <span class="hlt">air</span>-breathing activity increased significantly under hypoxic conditions. Hypoxic <span class="hlt">air</span>-breathing activity was negatively correlated to swimbladder PO 2 , indicating that the swimbladder was intensely used for <span class="hlt">gas</span> exchange under these conditions. In traira, the capacity of the ROS defense system, as assessed by measurement of activities of enzymes involved in ROS degradation and total glutathione (GSH + GSSG) <span class="hlt">concentration</span>, was elevated after 4 h of hyperoxic and/or hypoxic exposure, although swimbladder PO 2 was not affected. In jeju, experiencing a higher variability in swimbladder PO 2 due to the <span class="hlt">air</span>-breathing activity, only a reduced responsiveness of the ROS defense system to changing environmental PO 2 was detected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ACP....18.3523C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ACP....18.3523C"><span>Ice-nucleating particle <span class="hlt">concentrations</span> unaffected by urban <span class="hlt">air</span> pollution in Beijing, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Jie; Wu, Zhijun; Augustin-Bauditz, Stefanie; Grawe, Sarah; Hartmann, Markus; Pei, Xiangyu; Liu, Zirui; Ji, Dongsheng; Wex, Heike</p> <p>2018-03-01</p> <p>Exceedingly high levels of PM2.5 with complex chemical composition occur frequently in China. It has been speculated whether anthropogenic PM2.5 may significantly contribute to ice-nucleating particles (INP). However, few studies have focused on the ice-nucleating properties of urban particles. In this work, two ice-nucleating droplet arrays have been used to determine the atmospheric number <span class="hlt">concentration</span> of INP (NINP) in the range from -6 to -25 °C in Beijing. No correlations between NINP and either PM2.5 or black carbon mass <span class="hlt">concentrations</span> were found, although both varied by more than a factor of 30 during the sampling period. Similarly, there were no correlations between NINP and either total particle number <span class="hlt">concentration</span> or number <span class="hlt">concentrations</span> for particles with diameters > 500 nm. Furthermore, there was no clear difference between day and night samples. All these results indicate that Beijing <span class="hlt">air</span> pollution did not increase or decrease INP <span class="hlt">concentrations</span> in the examined temperature range above values observed in nonurban areas; hence, the background INP <span class="hlt">concentrations</span> might not be anthropogenically influenced as far as urban <span class="hlt">air</span> pollution is concerned, at least in the examined temperature range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26388365','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26388365"><span>Direct analysis of ultra-trace semiconductor <span class="hlt">gas</span> by inductively coupled plasma mass spectrometry coupled with <span class="hlt">gas</span> to particle conversion-<span class="hlt">gas</span> exchange technique.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ohata, Masaki; Sakurai, Hiromu; Nishiguchi, Kohei; Utani, Keisuke; Günther, Detlef</p> <p>2015-09-03</p> <p>An inductively coupled plasma mass spectrometry (ICPMS) coupled with <span class="hlt">gas</span> to particle conversion-<span class="hlt">gas</span> exchange technique was applied to the direct analysis of ultra-trace semiconductor <span class="hlt">gas</span> in ambient <span class="hlt">air</span>. The ultra-trace semiconductor gases such as arsine (AsH3) and phosphine (PH3) were converted to particles by reaction with ozone (O3) and ammonia (NH3) gases within a <span class="hlt">gas</span> to particle conversion device (GPD). The converted particles were directly introduced and measured by ICPMS through a <span class="hlt">gas</span> exchange device (GED), which could penetrate the particles as well as exchange to Ar from either non-reacted gases such as an <span class="hlt">air</span> or remaining gases of O3 and NH3. The particle size distribution of converted particles was measured by scanning mobility particle sizer (SMPS) and the results supported the elucidation of particle agglomeration between the particle converted from semiconductor <span class="hlt">gas</span> and the particle of ammonium nitrate (NH4NO3) which was produced as major particle in GPD. Stable time-resolved signals from AsH3 and PH3 in <span class="hlt">air</span> were obtained by GPD-GED-ICPMS with continuous <span class="hlt">gas</span> introduction; however, the slightly larger fluctuation, which could be due to the ionization fluctuation of particles in ICP, was observed compared to that of metal carbonyl <span class="hlt">gas</span> in Ar introduced directly into ICPMS. The linear regression lines were obtained and the limits of detection (LODs) of 1.5 pL L(-1) and 2.4 nL L(-1) for AsH3 and PH3, respectively, were estimated. Since these LODs revealed sufficiently lower values than the measurement <span class="hlt">concentrations</span> required from semiconductor industry such as 0.5 nL L(-1) and 30 nL L(-1) for AsH3 and PH3, respectively, the GPD-GED-ICPMS could be useful for direct and high sensitive analysis of ultra-trace semiconductor <span class="hlt">gas</span> in <span class="hlt">air</span>. Copyright © 2015 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApPhL.105a3505G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApPhL.105a3505G"><span>Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gulati, P.; Prakash, R.; Pal, U. N.; Kumar, M.; Vyas, V.</p> <p>2014-07-01</p> <p>A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and <span class="hlt">air</span> admixtures. The <span class="hlt">gas</span> mixture composition, chlorine <span class="hlt">gas</span> content, total <span class="hlt">gas</span> pressure, and <span class="hlt">air</span> pressure dependency of the UV intensity, has been analyzed. It is found that the larger <span class="hlt">concentration</span> of Cl2 deteriorates the performance of the developed source and around 2% Cl2 in this source produced optimum results. Furthermore, an addition of <span class="hlt">air</span> in the xenon and chlorine working <span class="hlt">gas</span> environment leads to achieve same intensity of UV-B light but at lower working <span class="hlt">gas</span> pressure where significant amount of <span class="hlt">gas</span> is <span class="hlt">air</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19245753','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19245753"><span>Isoflurane waste anesthetic <span class="hlt">gas</span> <span class="hlt">concentrations</span> associated with the open-drop method.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Taylor, Douglas K; Mook, Deborah M</p> <p>2009-01-01</p> <p>The open-drop technique is used frequently for anesthetic delivery to small rodents. Operator exposure to waste anesthetic <span class="hlt">gas</span> (WAG) is a potential occupational hazard if this method is used without WAG scavenging. This study was conducted to determine whether administration of isoflurane by the open-drop technique without exposure controls generates significant WAG <span class="hlt">concentrations</span>. We placed 0.1, 0.2, or 0.3 ml of liquid isoflurane into screw-top 500 or 1000 ml glass jars. WAG <span class="hlt">concentration</span> was measured at the opening of the container and 20 and 40 cm from the opening, a distance at which users likely would operate, at 1, 2, or 3 min WAG was measured by using a portable infrared <span class="hlt">gas</span> analyzer. Mean WAG <span class="hlt">concentrations</span> at the vessel opening were as high as 662 +/- 168 ppm with a 500 ml jar and 122 +/- 87 ppm with a 1000 ml jar. At operator levels, WAG <span class="hlt">concentrations</span> were always at or near 0 ppm. For measurements made at the vessel opening, time was the only factor that significantly affected WAG <span class="hlt">concentration</span> when using the 500 ml jar. Neither time nor liquid volume were significant factors when using 1000 ml jar. At all liquid volumes and time points, the WAG <span class="hlt">concentration</span> associated with using the 500 ml container was marginally to significantly greater than that for the 1000 ml jar.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27249104','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27249104"><span>Emissions from oil and <span class="hlt">gas</span> operations in the United States and their <span class="hlt">air</span> quality implications.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Allen, David T</p> <p>2016-06-01</p> <p>The energy supply infrastructure in the United States has been changing dramatically over the past decade. Increased production of oil and natural <span class="hlt">gas</span>, particularly from shale resources using horizontal drilling and hydraulic fracturing, made the United States the world's largest producer of oil and natural <span class="hlt">gas</span> in 2014. This review examines <span class="hlt">air</span> quality impacts, specifically, changes in greenhouse <span class="hlt">gas</span>, criteria <span class="hlt">air</span> pollutant, and <span class="hlt">air</span> toxics emissions from oil and <span class="hlt">gas</span> production activities that are a result of these changes in energy supplies and use. National emission inventories indicate that volatile organic compound (VOC) and nitrogen oxide (NOx) emissions from oil and <span class="hlt">gas</span> supply chains in the United States have been increasing significantly, whereas emission inventories for greenhouse gases have seen slight declines over the past decade. These emission inventories are based on counts of equipment and operational activities (activity factors), multiplied by average emission factors, and therefore are subject to uncertainties in these factors. Although uncertainties associated with activity data and missing emission source types can be significant, multiple recent measurement studies indicate that the greatest uncertainties are associated with emission factors. In many source categories, small groups of devices or sites, referred to as super-emitters, contribute a large fraction of emissions. When super-emitters are accounted for, multiple measurement approaches, at multiple scales, produce similar results for estimated emissions. Challenges moving forward include identifying super-emitters and reducing their emission magnitudes. Work done to date suggests that both equipment malfunction and operational practices can be important. Finally, although most of this review focuses on emissions from energy supply infrastructures, the regional <span class="hlt">air</span> quality implications of some coupled energy production and use scenarios are examined. These case studies suggest that both</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28043076','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28043076"><span>Bio-sniffer (<span class="hlt">gas</span>-phase biosensor) with secondary alcohol dehydrogenase (S-ADH) for determination of isopropanol in exhaled <span class="hlt">air</span> as a potential volatile biomarker.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chien, Po-Jen; Suzuki, Takuma; Tsujii, Masato; Ye, Ming; Toma, Koji; Arakawa, Takahiro; Iwasaki, Yasuhiko; Mitsubayashi, Kohji</p> <p>2017-05-15</p> <p>Exhaled breath analysis has attracted lots of researchers attention in the past decades due to its advantages such as its non-invasive property and the possibility of continuous monitoring. In addition, several volatile organic compounds in breath have been identified as biomarkers for some diseases. Particularly, studies have pointed out that <span class="hlt">concentration</span> of isopropanol (IPA) in exhaled <span class="hlt">air</span> might relate with certain illnesses such as liver disease, chronic obstructive pulmonary (COPD), and lung cancer. In this study, a highly sensitive and selective biochemical <span class="hlt">gas</span> sensor (bio-sniffer) for the breath IPA <span class="hlt">concentration</span> determination was constructed and optimized. This bio-sniffer measures the <span class="hlt">concentration</span> of IPA according to the fluorescence intensity of oxidized nicotinamide adenine dinucleotide (NADH), which was produced by an enzymatic reaction of secondary alcohol dehydrogenase (S-ADH). The NADH detection system employed an UV-LED as the excitation light, and a highly sensitive photomultiplier tube (PMT) as a fluorescence intensity detector. A <span class="hlt">gas</span>-sensing region was developed using an optical fiber probe equipped with a flow-cell and enzyme immobilized membrane, and connected to the NADH measurement system. The calibration range of the IPA bio-sniffer was confirmed from 1ppb to 9060ppb that was comparable to other IPA analysis methods. The results of the analysis of breath IPA <span class="hlt">concentration</span> in healthy subjects using the bio-sniffer showed a mean <span class="hlt">concentration</span> of 16.0ppb, which was similar to other studies. These results have demonstrated that this highly sensitive and selective bio-sniffer could be used to measure the IPA in exhaled <span class="hlt">air</span>, and it is expected to apply for breath IPA research and investigation of biomarkers for clinical diagnosis. Copyright © 2016 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6597272-ambient-air-concentration-sulfur-dioxide-affects-flight-activity-bees','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6597272-ambient-air-concentration-sulfur-dioxide-affects-flight-activity-bees"><span>Ambient <span class="hlt">air</span> <span class="hlt">concentration</span> of sulfur dioxide affects flight activity in bees</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Ginevan, M.E.; Lane, D.D.; Greenberg, L.</p> <p></p> <p>Three long-term (16 to 29 days) low-level (0.14 to 0.28 ppM) sulfur dioxide fumigations showed that exposure tothis <span class="hlt">gas</span> has deleterious effects on male sweat bees (Lasioglossum zephrum). Although effects on mortality were equivocal, flight activity was definitely reduced. Because flight is necessary for successful mating behavior, the results suggest that sulfur dioxide <span class="hlt">air</span> pollution could adversely affect this and doubtless other terrestrial insects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1911791L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1911791L"><span>A range of newly developed mobile generators to dynamically produce SI-traceable reference <span class="hlt">gas</span> mixtures for reactive compounds at atmospheric <span class="hlt">concentrations</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leuenberger, Daiana; Pascale, Céline; Guillevic, Myriam; Ackermann, Andreas; Niederhauser, Bernhard</p> <p>2017-04-01</p> <p>Three new mobile facilities have been developed at METAS to dynamically generate SI-traceable reference <span class="hlt">gas</span> mixtures for a variety of reactive compounds at atmospheric amount of substance fractions and at very low levels of uncertainty (Ux < 3%). We present three new portable "Reactive <span class="hlt">Gas</span> Standard ReGaS" reference <span class="hlt">gas</span> generators for the realisation of the following substances: ReGaS1: Ammonia and nitrogen dioxide in the nmol/mol (ppb) range ReGaS2: Volatile organic compounds (VOCs), e.g. limonene, alpha-pinene, MVK, MEK in the nmol/mol (ppb) range ReGaS-3: Fluorinated gases (F-gases, i.e. containing fluorine atoms) in the pmol/mol (ppt) range These three mobile generators have been designed and manufactured at METAS in the framework of the three EMRP projects MetNH3, KEY-VOCs and HIGHGAS. The method is based on permeation and subsequent dynamic dilution: A permeation tube containing the pure substance (e.g. NH3) is stored in the permeation chamber at constant temperature, pressure and matrix <span class="hlt">gas</span> flow (N2, purified <span class="hlt">air</span>, synthetic <span class="hlt">air</span>). Under such conditions the pure substance permeates at constant rate into the matrix <span class="hlt">gas</span> and can be diluted thereafter to the desired amount fractions in one or two subsequent steps. The permeation rate (mass loss over time) of the permeation tube is precisely calibrated in a fully traceable magnetic suspension balance. The carrier <span class="hlt">gas</span> is previously purified from the compounds of interest using commercially available purification cartridges. The permeation chambers of ReGaS2 and ReGaS3 have multiple individual cells allowing for the generation of mixtures containing up to 5 different components if required. ReGaS1 allows for the generation of one-component mixtures only. These primary mixtures are then diluted to the required amount of substance fractions using thermal mass flow controllers for full flexibility and adaptability of the generation process over the entire range of possible <span class="hlt">concentrations</span>. In order to considerably reduce</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23376324','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23376324"><span>Increased prandial <span class="hlt">air</span> swallowing and postprandial <span class="hlt">gas</span>-liquid reflux among patients refractory to proton pump inhibitor therapy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bravi, Ivana; Woodland, Philip; Gill, Ravinder S; Al-Zinaty, Mohannad; Bredenoord, Albert J; Sifrim, Daniel</p> <p>2013-07-01</p> <p>Many patients with gastroesophageal reflux disease (GERD) have persistent reflux despite treatment with proton pump inhibitors (PPIs). Mixed <span class="hlt">gas</span>-liquid reflux events are more likely to be perceived as symptomatic. We used esophageal impedance monitoring to investigate whether esophageal <span class="hlt">gas</span> is processed differently among patients with GERD who do and do not respond to PPI therapy. We performed a prospective study of 44 patients with typical reflux symptoms with high levels of esophageal acid exposure during a 24-hour period; 18 patients were fully responsive, and 26 did not respond to PPI therapy. Twenty-four-hour pH impedance recordings were analyzed for fasting and prandial <span class="hlt">air</span> swallows and reflux characteristics, including the presence of <span class="hlt">gas</span> in the refluxate. PPI-refractory patients had a higher number (83.1 ± 12.7 vs 47.8 ± 7.3, P < .05) and rate (10.5 ± 1.4 vs 5.9 ± 0.8/10 minutes, P < .05) of prandial <span class="hlt">air</span> swallows than patients who responded to PPI therapy; they also had a higher number (25.5 ± 4.0 vs 16.8 ± 3.3, P < .05) and proportion (70% ± 0.03% vs 54% ± 0.06%, P < .05) of postprandial, mixed <span class="hlt">gas</span>-liquid reflux. Symptoms of PPI-refractory patients were more often preceded by mixed <span class="hlt">gas</span>-liquid reflux events than those of PPI responders. Fasting <span class="hlt">air</span> swallowing and other reflux characteristics did not differ between patients who did and did not respond to PPIs. Some patients with GERD who do not respond to PPI therapy swallow more <span class="hlt">air</span> at mealtime than those who respond to PPIs and also have more reflux episodes that contain <span class="hlt">gas</span>. These factors, combined with mucosal sensitization by previous exposure to acid, could affect perception of symptoms. These patients, who can be identified on standard 24-hour pH impedance monitoring, might be given behavioral therapy to reduce mealtime <span class="hlt">air</span> swallowing. Copyright © 2013 AGA Institute. Published by Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16604407','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16604407"><span>Potential <span class="hlt">air</span> contamination during CO2 angiography using a hand-held syringe: theoretical considerations and <span class="hlt">gas</span> chromatography.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cho, David R; Cho, Kyung J; Hawkins, Irvin F</p> <p>2006-01-01</p> <p>To assess <span class="hlt">air</span> contamination in the hand-held syringes currently used for CO2 delivery and to determine whether there is an association between their position and the rate of <span class="hlt">air</span> contamination. Assessment of <span class="hlt">air</span> contamination in the syringe (20 ml) included theoretical modeling, mathematical calculation, and <span class="hlt">gas</span> chromatography (GC). The model was used with Fick's first law to calculate the diffusion of CO2 and the amount of <span class="hlt">air</span> contamination. For GC studies, the syringes were placed in the upright, horizontal, and inverted positions and <span class="hlt">gas</span> samples were obtained after 5, 10, 20, 30, and 60 min. All trials with each position for each sampling time were performed five times. The amounts of <span class="hlt">air</span> contamination with time calculated mathematically were 5-10% less than those of GC. With the diffusivity of <span class="hlt">air</span>-CO2 at 0.1599 cm2/sec (9.594 cm2/min), <span class="hlt">air</span> contamination was calculated to be 60% at 60 min. With GC <span class="hlt">air</span> contamination was 13% at 5 min, 31% at 20 min, 43% at 30 min, and 68% at 60 min. There was no difference in <span class="hlt">air</span> contamination between the different syringe positions. <span class="hlt">Air</span> contamination occurs in hand-held syringes filled with CO2 when they are open to the ambient <span class="hlt">air</span>. The amounts of <span class="hlt">air</span> contamination over time are similar among syringes placed in the upright, horizontal, and inverted positions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MsT.........20K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MsT.........20K"><span>Flammability limits of lithium-ion battery thermal runaway vent <span class="hlt">gas</span> in <span class="hlt">air</span> and the inerting effects of halon 1301</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karp, Matthew Eugene</p> <p></p> <p>Lithium-ion (rechargeable) and lithium-metal (non-rechargeable) battery cells put aircraft at risk of igniting and fueling fires. Lithium batteries can be packed in bulk and shipped in the cargo holds of freighter aircraft; currently lithium batteries are banned from bulk shipment on passenger aircraft [1]. The federally regulated Class C cargo compartment extinguishing system's utilization of a 5 %vol Halon 1301 knockdown <span class="hlt">concentration</span> and a sustained 3 %vol Halon 1301 may not be sufficient at inerting lithium-ion battery vent <span class="hlt">gas</span> and <span class="hlt">air</span> mixtures [2]. At 5 %vol Halon 1301 the flammability limits of lithium-ion premixed battery vent <span class="hlt">gas</span> (Li-Ion pBVG) in <span class="hlt">air</span> range from 13.80 %vol to 26.07 %vol Li-Ion pBVG. Testing suggests that 8.59 %vol Halon 1301 is required to render all ratios of the Li-Ion pBVG in <span class="hlt">air</span> inert. The lower flammability limit (LFL) and upper flammability limit (UFL) of hydrogen and <span class="hlt">air</span> mixtures are 4.95 %vol and 76.52 %vol hydrogen, respectively. With the addition of 10 %vol and 20 %vol Halon 1301 the LFL is 9.02 %vol and 11.55 %vol hydrogen, respectively, and the UFL is 45.70 %vol and 28.39 %vol hydrogen, respectively. The minimum inerting <span class="hlt">concentration</span> (MIC) of Halon 1301 in hydrogen and <span class="hlt">air</span> mixtures is 26.72 %vol Halon 1301 at 16.2 %vol hydrogen. The LFL and UFL of Li-Ion pBVG and <span class="hlt">air</span> mixtures are 7.88 %vol and 37.14 %vol Li-Ion pBVG, respectively. With the addition of 5 %vol, 7 %vol, and 8 %vol Halon 1301 the LFL is 13.80 %vol, 16.15 %vol, and 17.62 % vol Li-Ion pBVG, respectively, and the UFL is 26.07 %vol, 23.31 %vol, and 21.84 %vol Li- Ion pBVG, respectively. The MIC of Halon 1301 in Li-Ion pBVG and <span class="hlt">air</span> mixtures is 8.59 %vol Halon 1301 at 19.52 %vol Li-Ion pBVG. Le Chatelier's mixing rule has been shown to be an effective measure for estimating the flammability limits of Li-Ion pBVGes. The LFL has a 1.79 % difference while the UFL has a 4.53 % difference. The state of charge (SOC) affects the flammability limits in an apparent parabolic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMEP43D0770P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP43D0770P"><span>Wind driven vertical transport in a vegetated, wetland water column with <span class="hlt">air</span>-water <span class="hlt">gas</span> exchange</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poindexter, C.; Variano, E. A.</p> <p>2010-12-01</p> <p>Flow around arrays of cylinders at low and intermediate Reynolds numbers has been studied numerically, analytically and experimentally. Early results demonstrated that at flow around randomly oriented cylinders exhibits reduced turbulent length scales and reduced diffusivity when compared to similarly forced, unimpeded flows (Nepf 1999). While horizontal dispersion in flows through cylinder arrays has received considerable research attention, the case of vertical dispersion of reactive constituents has not. This case is relevant to the vertical transfer of dissolved gases in wetlands with emergent vegetation. We present results showing that the presence of vegetation can significantly enhance vertical transport, including <span class="hlt">gas</span> transfer across the <span class="hlt">air</span>-water interface. Specifically, we study a wind-sheared <span class="hlt">air</span>-water interface in which randomly arrayed cylinders represent emergent vegetation. Wind is one of several processes that may govern physical dispersion of dissolved gases in wetlands. Wind represents the dominant force for <span class="hlt">gas</span> transfer across the <span class="hlt">air</span>-water interface in the ocean. Empirical relationships between wind and the <span class="hlt">gas</span> transfer coefficient, k, have been used to estimate spatial variability of CO2 exchange across the worlds’ oceans. Because wetlands with emergent vegetation are different from oceans, different model of wind effects is needed. We investigated the vertical transport of dissolved oxygen in a scaled wetland model built inside a laboratory tank equipped with an open-ended wind tunnel. Plastic tubing immersed in water to a depth of approximately 40 cm represented emergent vegetation of cylindrical form such as hard-stem bulrush (Schoenoplectus acutus). After partially removing the oxygen from the tank water via reaction with sodium sulfite, we used an optical probe to measure dissolved oxygen at mid-depth as the tank water re-equilibrated with the <span class="hlt">air</span> above. We used dissolved oxygen time-series for a range of mean wind speeds to estimate the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23841677','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23841677"><span>Methods to reduce the CO(2) <span class="hlt">concentration</span> of educational buildings utilizing internal ventilation by transferred <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kalema, T; Viot, M</p> <p>2014-02-01</p> <p>The aim of this study is to develop internal ventilation by transferred <span class="hlt">air</span> to achieve a good indoor climate with low energy consumption in educational buildings with constant <span class="hlt">air</span> volume (CAV) ventilation. Both measurements of CO2 <span class="hlt">concentration</span> and a multi-room calculation model are presented. The study analyzes how to use more efficiently the available spaces and the capacity of CAV ventilation systems in existing buildings and the impact this has on the indoor <span class="hlt">air</span> quality and the energy consumption of the ventilation. The temperature differences can be used to create natural ventilation airflows between neighboring spaces. The behavior of temperature-driven airflows between rooms was studied and included in the calculation model. The effect of openings between neighboring spaces, such as doors or large apertures in the walls, on the CO2 <span class="hlt">concentration</span> was studied in different classrooms. The <span class="hlt">air</span> temperatures and CO2 <span class="hlt">concentrations</span> were measured using a wireless, internet-based measurement system. The multi-room calculation model predicted the CO2 <span class="hlt">concentration</span> in the rooms, which was then compared with the measured ones. Using transferred <span class="hlt">air</span> between occupied and unoccupied spaces can noticeably reduce the total mechanical ventilation rates needed to keep a low CO2 <span class="hlt">concentration</span>. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPIE10329E..2RG','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPIE10329E..2RG"><span><span class="hlt">Gas</span> monitoring onboard ISS using FTIR spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gisi, Michael; Stettner, Armin; Seurig, Roland; Honne, Atle; Witt, Johannes; Rebeyre, Pierre</p> <p>2017-06-01</p> <p>In the confined, enclosed environment of a spacecraft, the <span class="hlt">air</span> quality must be monitored continuously in order to safeguard the crew's health. For this reason, OHB builds the ANITA2 (Analysing Interferometer for Ambient <span class="hlt">Air</span>) technology demonstrator for trace <span class="hlt">gas</span> monitoring onboard the International Space Station (ISS). The measurement principle of ANITA2 is based on the Fourier Transform Infrared (FTIR) technology with dedicated <span class="hlt">gas</span> analysis software from the Norwegian partner SINTEF. This combination proved to provide high sensitivity, accuracy and precision for parallel measurements of 33 trace gases simultaneously onboard ISS by the precursor instrument ANITA1. The paper gives a technical overview about the opto-mechanical components of ANITA2, such as the interferometer, the reference Laser, the infrared source and the <span class="hlt">gas</span> cell design and a quick overview about the <span class="hlt">gas</span> analysis. ANITA2 is very well suited for measuring <span class="hlt">gas</span> <span class="hlt">concentrations</span> specifically but not limited to usage onboard spacecraft, as no consumables are required and measurements are performed autonomously. ANITA2 is a programme under the contract of the European Space Agency, and the <span class="hlt">air</span> quality monitoring system is a stepping stone into the future, as a precursor system for manned exploration missions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A31B2173S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A31B2173S"><span>Eagle Ford Shale BTEX and NOx <span class="hlt">concentrations</span> are dominated by oil and <span class="hlt">gas</span> industry emissions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schade, G. W.; Roest, G. S.</p> <p>2017-12-01</p> <p>US shale oil and <span class="hlt">gas</span> exploration has been identified as a major source of greenhouse gases and non-methane hydrocarbon (NMHC) emissions to the atmosphere. Here, we present a detailed analysis of 2015 <span class="hlt">air</span> quality data acquired by the Texas Commission on Environmental Quality (TCEQ) at an <span class="hlt">air</span> quality monitoring station in Karnes County, TX, central to Texas' Eagle Ford shale area. Data include time series of hourly measured NMHCs, nitrogen oxides (NOx), and hydrogen sulfide (H2S) alongside meteorological measurements. The monitor was located in Karnes City, and thus affected by various anthropogenic emissions, including traffic and oil and <span class="hlt">gas</span> exploration sources. Highest mixing ratios measured in 2015 included nearly 1 ppm ethane, 0.8 ppm propane, alongside 4 ppb benzene. A least-squares minimization non-negative matrix factorization (NMF) analysis, tested with prior data analyzed using standard PMF-2 software, showed six major emission sources: an evaporative and fugitive source, a flaring source, a traffic source, an oil field source, a diesel source, and an industrial manufacturing source, together accounting for more than 95% of data set variability, and interpreted using NMHC composition and meteorological data. Factor scores strongly suggest that NOx emissions are dominated by flaring and associated sources, such as diesel compressor engines, likely at midstream facilities, while traffic in this rural area is a minor NOx source. The results support, but exceed existing 2012 emission inventories estimating that local traffic emitted seven times fewer NOx than oil and <span class="hlt">gas</span> exploration sources in the county. Sources of <span class="hlt">air</span> toxics such as the BTEX compounds are also dominated by oil and <span class="hlt">gas</span> exploration sources, but are more equally distributed between the associated factors. Benzene abundance is only 20-40% associated with traffic sources, and may thus be 2.5-5 times higher now than prior to the shale boom in this area. Although the monitor was located relatively</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70024368','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70024368"><span>Relationship of <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span> to porosity and reflection amplitude in a research well, Mackenzie Delta, Canada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Jin, Y.K.; Lee, M.W.; Collett, T.S.</p> <p>2002-01-01</p> <p>Well logs acquired at the Mallik 2L-38 <span class="hlt">gas</span> hydrate research well. Mackenzie Delta, Canada, reveal a distinct trend showing that the resistivity of <span class="hlt">gas</span>-hydrate-bearing sediments increases with increases in density porosities. This trend, opposite to the general trend of decrease in resistivity with porosity, implies that <span class="hlt">gas</span> hydrates are more <span class="hlt">concentrated</span> in the higher porosity. Using the Mallik 2L-38 well data, a proportional <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span> (PGHC) model, which states that the <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span> in the sediment's pore space is linearly proportional to porosity, is proposed for the general habitat of <span class="hlt">gas</span> hydrate in sediments. Anomalous data (less than 6% of the total data) outside the dominant observed trend can be explained by local geological characteristics. The anomalous data analysis indicates that highly <span class="hlt">concentrated</span> <span class="hlt">gas</span>-hydrate-bearing layers would be expected where sediments have high proportions of gravel and coarse sand. Using the parameters in the PGHC model determined from resistivity-porosity logs, it is possible to qualitatively predict the degree of reflection amplitude variations in seismic profiles. Moderate-to-strong reflections are expected for the Mallik 2L-38 well. ?? 2002 Elsevier Science Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23611693','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23611693"><span>Argon <span class="hlt">concentration</span> time-series as a tool to study <span class="hlt">gas</span> dynamics in the hyporheic zone.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mächler, Lars; Brennwald, Matthias S; Kipfer, Rolf</p> <p>2013-07-02</p> <p>The oxygen dynamics in the hyporheic zone of a peri-alpine river (Thur, Switzerland), were studied through recording and analyzing the <span class="hlt">concentration</span> time-series of dissolved argon, oxygen, carbon dioxide, and temperature during low flow conditions, for a period of one week. The argon <span class="hlt">concentration</span> time-series was used to investigate the physical <span class="hlt">gas</span> dynamics in the hyporheic zone. Differences in the transport behavior of heat and <span class="hlt">gas</span> were determined by comparing the diel temperature evolution of groundwater to the measured <span class="hlt">concentration</span> of dissolved argon. These differences were most likely caused by vertical heat transport which influenced the local groundwater temperature. The argon <span class="hlt">concentration</span> time-series were also used to estimate travel times by cross correlating argon <span class="hlt">concentrations</span> in the groundwater with argon <span class="hlt">concentrations</span> in the river. The information gained from quantifying the physical <span class="hlt">gas</span> transport was used to estimate the oxygen turnover in groundwater after water recharge. The resulting oxygen turnover showed strong diel variations, which correlated with the water temperature during groundwater recharge. Hence, the variation in the consumption rate was most likely caused by the temperature dependence of microbial activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=336238&Lab=NERL&keyword=account+AND+information&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=336238&Lab=NERL&keyword=account+AND+information&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>Modeling the impact of solid noise barriers on near road <span class="hlt">air</span> quality</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Studies based on field measurements, wind tunnel experiments, and controlled tracer <span class="hlt">gas</span> releases indicate that solid, roadside noise barriers can lead to reductions in downwind near-road <span class="hlt">air</span> pollutant <span class="hlt">concentrations</span>. A tracer <span class="hlt">gas</span> study showed that a solid barrier reduced pollutan...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27089333','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27089333"><span>Changes in <span class="hlt">Air</span> CO₂ <span class="hlt">Concentration</span> Differentially Alter Transcript Levels of NtAQP1 and NtPIP2;1 Aquaporin Genes in Tobacco Leaves.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Secchi, Francesca; Schubert, Andrea; Lovisolo, Claudio</p> <p>2016-04-14</p> <p>The aquaporin specific control on water versus carbon pathways in leaves is pivotal in controlling <span class="hlt">gas</span> exchange and leaf hydraulics. We investigated whether Nicotiana tabacum aquaporin 1 (NtAQP1) and Nicotiana tabacum plasma membrane intrinsic protein 2;1 (NtPIP2;1) gene expression varies in tobacco leaves subjected to treatments with different CO₂ <span class="hlt">concentrations</span> (ranging from 0 to 800 ppm), inducing changes in photosynthesis, stomatal regulation and water evaporation from the leaf. Changes in <span class="hlt">air</span> CO₂ <span class="hlt">concentration</span> ([CO₂]) affected net photosynthesis (Pn) and leaf substomatal [CO₂] (Ci). Pn was slightly negative at 0 ppm <span class="hlt">air</span> CO₂; it was one-third that of ambient controls at 200 ppm, and not different from controls at 800 ppm. Leaves fed with 800 ppm [CO₂] showed one-third reduced stomatal conductance (gs) and transpiration (E), and their gs was in turn slightly lower than in 200 ppm- and in 0 ppm-treated leaves. The 800 ppm <span class="hlt">air</span> [CO₂] strongly impaired both NtAQP1 and NtPIP2;1 gene expression, whereas 0 ppm <span class="hlt">air</span> [CO₂], a <span class="hlt">concentration</span> below any in vivo possible conditions and specifically chosen to maximize the gene expression alteration, increased only the NtAQP1 transcript level. We propose that NtAQP1 expression, an aquaporin devoted to CO₂ transport, positively responds to CO₂ scarcity in the <span class="hlt">air</span> in the whole range 0-800 ppm. On the contrary, expression of NtPIP2;1, an aquaporin not devoted to CO₂ transport, is related to water balance in the leaf, and changes in parallel with gs. These observations fit in a model where upregulation of leaf aquaporins is activated at low Ci, while downregulation occurs when high Ci saturates photosynthesis and causes stomatal closure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/953377-comparison-mold-concentrations-quantified-msqpcr-indoor-outdoor-air-sampled-simultaneously','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/953377-comparison-mold-concentrations-quantified-msqpcr-indoor-outdoor-air-sampled-simultaneously"><span>Comparison of mold <span class="hlt">concentrations</span> quantified by MSQPCR in indoor and outdoor <span class="hlt">air</span> sampled simultaneously</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Meklin, Teija; Reponen, Tina; McKinstry, Craig A.</p> <p></p> <p>Mold specific quantitative PCR (MSQPCR) was used to measure the <span class="hlt">concentrations</span> of 36 mold species in dust and in indoor and in outdoor <span class="hlt">air</span> samples that were taken simultaneously in 17 homes in Cincinnati with no-known water damage. The total spore <span class="hlt">concentrations</span> in the indoor (I) and outdoor (O) <span class="hlt">air</span> samples were statistically significantly different and the <span class="hlt">concentrations</span> in the three sample types of many of the individual species were significantly different (p < 0.05 based on the Wilcoxon Signed Rank Test). The I/O ratios of the averages or geometric means of the individual species were generally less than 1;more » but these I/O ratios were quite variable ranging from 0.03 for A. sydowii to 1.2 for Acremonium strictum. There were no significant correlations for the 36 specific mold <span class="hlt">concentrations</span> between the dust samples and the indoor or outdoor <span class="hlt">air</span> samples (based on the Spearman’s Rho test). The indoor and outdoor <span class="hlt">air</span> <span class="hlt">concentrations</span> of 32 of the species were not correlated. Only Aspergillus penicillioides, C. cladosporioides types 1 and 2 and C. herbarum had sufficient data to estimate a correlation at rho > 0.5 with signicance (p < 0.05) In six of these homes, a previous dust sample had been collected and analyzed 2 years earlier. The ERMI© values for the dust samples taken in the same home two years apart were not significantly different (p=0.22) based on Wilcoxon Signed Rank Test.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AtmEn..42..757G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AtmEn..42..757G"><span>Impact of ventilation scenario on <span class="hlt">air</span> exchange rates and on indoor particle number <span class="hlt">concentrations</span> in an <span class="hlt">air</span>-conditioned classroom</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, H.; Morawska, L.; He, C.; Gilbert, D.</p> <p></p> <p>A 2-week intensive measurement campaign of indoor and outdoor <span class="hlt">air</span> pollution was carried out in September 2006, in a primary school to investigate indoor-outdoor correlations of particle number (PN) <span class="hlt">concentrations</span>, and the impact of <span class="hlt">air</span> exchange rate (ACH) on the indoor PN <span class="hlt">concentration</span>. The ACHs in the classroom for different conditions associated with window opening and the operational status of <span class="hlt">air</span> conditioners (A/C) and fans were tested. As expected, the lowest ACH (0.12 h -1) was found when the windows were closed and A/C and fans were off. In contrast, the highest ACH (7.92 h -1) was observed when the windows were opened and A/C and fans were all on. The analysis of the PN I/ O ratios at different ACHs in the absence of indoor sources indicates that the mean I/ O ratio was 0.621±0.007 (mean±95% confidence interval) when the windows were closed, and A/C and fans were off; 0.524±0.023 when windows were closed, fans were off and A/C was on; and 0.502±0.029 when windows were closed, A/C was off and fans were on. To further understand the relationship between indoor and outdoor PN <span class="hlt">concentrations</span>, the impact of outdoor PN <span class="hlt">concentration</span> on I/ O ratios at different ACHs was investigated. It was found that the relationship between outdoor PN <span class="hlt">concentration</span> and the I/ O ratio at different ACHs followed a power trendline with an equation of I/ O ratio= A PN out-b ( A and b are coefficients, PN out is outdoor PN <span class="hlt">concentration</span>), suggesting that the penetration efficiency decreased with increasing outdoor PN <span class="hlt">concentration</span>. It is the first time we found that when the outdoor PN <span class="hlt">concentration</span> increased there was an associated increase in the <span class="hlt">concentration</span> of nano-particles, which have been demonstrated to have higher deposition rates and lower penetration efficiencies. Based on the above equation, the study also showed a significant effect of ACH on indoor PN <span class="hlt">concentrations</span> under stable outdoor PN <span class="hlt">concentrations</span>. In general, the higher the ACH was, the lower the indoor PN</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AtmEn..45..935W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AtmEn..45..935W"><span>Landfills as sources of polyfluorinated compounds, polybrominated diphenyl ethers and musk fragrances to ambient <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weinberg, Ingo; Dreyer, Annekatrin; Ebinghaus, Ralf</p> <p>2011-02-01</p> <p>In order to investigate landfills as sources of polyfluorinated compounds (PFCs), polybrominated diphenyl ethers (PBDEs) and synthetic musk fragrances to the atmosphere, <span class="hlt">air</span> samples were simultaneously taken at two landfills (one active and one closed) and two reference sites using high volume <span class="hlt">air</span> samplers. Contaminants were accumulated on glass fiber filters (particle phase) and PUF/XAD-2/PUF cartridges (<span class="hlt">gas</span> phase), extracted by methyl-tert butyl ether/acetone (neutral PFCs), methanol (ionic PFCs) or hexane/acetone (PBDEs, musk fragrances), and detected by GC-MS (neutral PFCs, PBDEs, musk fragrances) or HPLC-MS/MS (ionic PFCs). Total <span class="hlt">concentrations</span> ranged from 84 to 706 pg m -3 (volatile PFCs, <span class="hlt">gas</span> phase), from <MQL to 42 pg m -3 (ionic PFCs, particle phase), from 204 to 1963 pg m -3 (synthetic musk fragrances, <span class="hlt">gas</span> + particle phase) and from 1 to 11 pg m -3 (PBDEs, <span class="hlt">gas</span> + particle phase). Observed sum <span class="hlt">concentrations</span> of PFCs and synthetic musk fragrances and partly PBDE <span class="hlt">concentrations</span> were elevated at landfill sites compared to corresponding reference sites. <span class="hlt">Concentrations</span> determined at the active landfill were higher than those of the inactive landfill. Overall, landfills can be regarded as a source of synthetic musk fragrances, several PFCs and potentially of PBDEs to ambient <span class="hlt">air</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1039895','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1039895"><span>Efficient <span class="hlt">gas</span>-separation process to upgrade dilute methane stream for use as fuel</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Wijmans, Johannes G [Menlo Park, CA; Merkel, Timothy C [Menlo Park, CA; Lin, Haiqing [Mountain View, CA; Thompson, Scott [Brecksville, OH; Daniels, Ramin [San Jose, CA</p> <p>2012-03-06</p> <p>A membrane-based <span class="hlt">gas</span> separation process for treating <span class="hlt">gas</span> streams that contain methane in low <span class="hlt">concentrations</span>. The invention involves flowing the stream to be treated across the feed side of a membrane and flowing a sweep <span class="hlt">gas</span> stream, usually <span class="hlt">air</span>, across the permeate side. Carbon dioxide permeates the membrane preferentially and is picked up in the sweep <span class="hlt">air</span> stream on the permeate side; oxygen permeates in the other direction and is picked up in the methane-containing stream. The resulting residue stream is enriched in methane as well as oxygen and has an EMC value enabling it to be either flared or combusted by mixing with ordinary <span class="hlt">air</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22494639','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22494639"><span>Development of analysis of volatile polyfluorinated alkyl substances in indoor <span class="hlt">air</span> using thermal desorption-<span class="hlt">gas</span> chromatography-mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, Yaoxing; Chang, Victor W-C</p> <p>2012-05-18</p> <p>The study attempts to utilize thermal desorption (TD) coupled with <span class="hlt">gas</span> chromatography-mass spectrometry (GC-MS) for determination of indoor airborne volatile polyfluorinated alkyl substances (PFASs), including four fluorinated alcohols (FTOHs), two fluorooctane sulfonamides (FOSAs), and two fluorooctane sulfonamidoethanols (FOSEs). Standard stainless steel tubes of Tenax/Carbograph 1 TD were employed for low-volume sampling and exhibited minimal breakthrough of target analytes in sample collection. The method recoveries were in the range of 88-119% for FTOHs, 86-138% for FOSAs, exhibiting significant improvement compared with other existing <span class="hlt">air</span> sampling methods. However, the widely reported high method recoveries of FOSEs were also observed (139-210%), which was probably due to the structural differences between FOSEs and internal standards. Method detection limit, repeatability, linearity, and accuracy were reported as well. The approach has been successfully applied to routine quantification of targeted PFASs in indoor environment of Singapore. The significantly shorter sampling time enabled the observation of variations of <span class="hlt">concentrations</span> of targeted PFASs within different periods of a day, with higher <span class="hlt">concentration</span> levels at night while ventilation systems were shut off. This indicated the existence of indoor sources and the importance of building ventilation and <span class="hlt">air</span> conditioning system. Copyright © 2012 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22303962-ultraviolet-radiation-enhancement-dielectric-barrier-discharge-based-xenon-chloride-exciplex-source-air','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22303962-ultraviolet-radiation-enhancement-dielectric-barrier-discharge-based-xenon-chloride-exciplex-source-air"><span>Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gulati, P., E-mail: pgulati1512@gmail.com; Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022; Prakash, R.</p> <p>2014-07-07</p> <p>A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and <span class="hlt">air</span> admixtures. The <span class="hlt">gas</span> mixture composition, chlorine <span class="hlt">gas</span> content, total <span class="hlt">gas</span> pressure, and <span class="hlt">air</span> pressure dependency of the UV intensity, has been analyzed. It is found that the larger <span class="hlt">concentration</span> of Cl{sub 2} deteriorates the performance of the developed source and around 2% Cl{sub 2} in this source produced optimum results. Furthermore, anmore » addition of <span class="hlt">air</span> in the xenon and chlorine working <span class="hlt">gas</span> environment leads to achieve same intensity of UV-B light but at lower working <span class="hlt">gas</span> pressure where significant amount of <span class="hlt">gas</span> is <span class="hlt">air</span>.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=175503&keyword=reactive+AND+program&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=175503&keyword=reactive+AND+program&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>A METHOD OF ASSESSING <span class="hlt">AIR</span> TOXICS <span class="hlt">CONCENTRATIONS</span> IN URBAN AREAS USING MOBILE PLATFORM MEASUREMENTS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The objective of this paper is to demonstrate an approach to characterize the spatial variability in ambient <span class="hlt">air</span> <span class="hlt">concentrations</span> using mobile platform measurements. This approach may be useful for <span class="hlt">air</span> toxic assessments in Environmental Justice applications, epidemiological studies...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25d3106M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25d3106M"><span>Effect of injection-<span class="hlt">gas</span> <span class="hlt">concentration</span> on the electron beam quality from a laser-plasma accelerator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mirzaie, Mohammad; Zhang, Guobo; Li, Song; Gao, Kai; Li, Guangyu; Ain, Quratul; Hafz, Nasr A. M.</p> <p>2018-04-01</p> <p>By using 25-45 TW ultra-short (30 fs) laser pulses, we report on the effect of the injection <span class="hlt">gas</span> <span class="hlt">concentration</span> on the quality of electron beams generated by a laser-driven plasma wakefield acceleration employing the ionization-injection. For a plasma formed from helium-nitrogen <span class="hlt">gas</span> mixture and depending on the <span class="hlt">concentration</span> of the nitrogen <span class="hlt">gas</span>, we could distinguish a clear trend for the quality of the generated electron beams in terms of their peak energy, energy-spread, divergence angle, and beam charge. The results clearly showed that the lower the nitrogen <span class="hlt">concentration</span>, the better the quality (higher peak energy, smaller energy spread, and smaller emittance) of the generated electron beams. The results are in reasonable agreement with two-dimensional particle-in-cell simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1367812','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1367812"><span>Performance Testing of Tracer <span class="hlt">Gas</span> and Tracer Aerosol Detectors for use in Radionuclide NESHAP Compliance Testing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Fuehne, David Patrick; Lattin, Rebecca Renee</p> <p></p> <p>The Rad-NESHAP program, part of the <span class="hlt">Air</span> Quality Compliance team of LANL’s Compliance Programs group (EPC-CP), and the Radiation Instrumentation & Calibration team, part of the Radiation Protection Services group (RP-SVS), frequently partner on issues relating to characterizing <span class="hlt">air</span> flow streams. This memo documents the most recent example of this partnership, involving performance testing of sulfur hexafluoride detectors for use in stack <span class="hlt">gas</span> mixing tests. Additionally, members of the Rad-NESHAP program performed a functional trending test on a pair of optical particle counters, comparing results from a non-calibrated instrument to a calibrated instrument. Prior to commissioning a new stack samplingmore » system, the ANSI Standard for stack sampling requires that the stack sample location must meet several criteria, including uniformity of tracer <span class="hlt">gas</span> and aerosol mixing in the <span class="hlt">air</span> stream. For these mix tests, tracer media (sulfur hexafluoride <span class="hlt">gas</span> or liquid oil aerosol particles) are injected into the stack <span class="hlt">air</span> stream and the resulting <span class="hlt">air</span> <span class="hlt">concentrations</span> are measured across the plane of the stack at the proposed sampling location. The coefficient of variation of these media <span class="hlt">concentrations</span> must be under 20% when evaluated over the central 2/3 area of the stack or duct. The instruments which measure these <span class="hlt">air</span> <span class="hlt">concentrations</span> must be tested prior to the stack tests in order to ensure their linear response to varying <span class="hlt">air</span> <span class="hlt">concentrations</span> of either tracer <span class="hlt">gas</span> or tracer aerosol. The instruments used in tracer <span class="hlt">gas</span> and aerosol mix testing cannot be calibrated by the LANL Standards and Calibration Laboratory, so they would normally be sent off-site for factory calibration by the vendor. Operational requirements can prevent formal factory calibration of some instruments after they have been used in hazardous settings, e.g., within a radiological facility with potential airborne contamination. The performance tests described in this document are intended to demonstrate the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28288421','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28288421"><span>Evaluating the impact of ambient benzene vapor <span class="hlt">concentrations</span> on product water from Condensation Water From <span class="hlt">Air</span> technology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kinder, Katherine M; Gellasch, Christopher A; Dusenbury, James S; Timmes, Thomas C; Hughes, Thomas M</p> <p>2017-07-15</p> <p>Globally, drinking water resources are diminishing in both quantity and quality. This situation has renewed interest in Condensation Water From <span class="hlt">Air</span> (CWFA) technology, which utilizes water vapor in the <span class="hlt">air</span> to produce water for both potable and non-potable purposes. However, there are currently insufficient data available to determine the relationship between <span class="hlt">air</span> contaminants and the rate at which they are transferred from the <span class="hlt">air</span> into CWFA untreated product water. This study implemented a novel experimental method utilizing an environmental test chamber to evaluate how <span class="hlt">air</span> quality and temperature affects CWFA untreated product water quality in order to collect data that will inform the type of water treatment required to protect human health. This study found that temperature and benzene <span class="hlt">air</span> <span class="hlt">concentration</span> affected the untreated product water from a CWFA system. Benzene vapor <span class="hlt">concentrations</span> representing a polluted outdoor environment resulted in benzene product water <span class="hlt">concentrations</span> between 15% and 23% of the USEPA drinking water limit of 5μg/l. In contrast, product water benzene <span class="hlt">concentrations</span> representing an indoor industrial environment were between 1.4 and 2.4 times higher than the drinking water limit. Lower condenser coil temperatures were correlated with an increased <span class="hlt">concentration</span> of benzene in the product water. Environmental health professionals and engineers can integrate the results of this assessment to predict benzene <span class="hlt">concentrations</span> in the product water and take appropriate health protective measures. Published by Elsevier B.V.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AtmEn..44.3015C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AtmEn..44.3015C"><span>An enhanced PM 2.5 <span class="hlt">air</span> quality forecast model based on nonlinear regression and back-trajectory <span class="hlt">concentrations</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cobourn, W. Geoffrey</p> <p>2010-08-01</p> <p>An enhanced PM 2.5 <span class="hlt">air</span> quality forecast model based on nonlinear regression (NLR) and back-trajectory <span class="hlt">concentrations</span> has been developed for use in the Louisville, Kentucky metropolitan area. The PM 2.5 <span class="hlt">air</span> quality forecast model is designed for use in the warm season, from May through September, when PM 2.5 <span class="hlt">air</span> quality is more likely to be critical for human health. The enhanced PM 2.5 model consists of a basic NLR model, developed for use with an automated <span class="hlt">air</span> quality forecast system, and an additional parameter based on upwind PM 2.5 <span class="hlt">concentration</span>, called PM24. The PM24 parameter is designed to be determined manually, by synthesizing backward <span class="hlt">air</span> trajectory and regional <span class="hlt">air</span> quality information to compute 24-h back-trajectory <span class="hlt">concentrations</span>. The PM24 parameter may be used by <span class="hlt">air</span> quality forecasters to adjust the forecast provided by the automated forecast system. In this study of the 2007 and 2008 forecast seasons, the enhanced model performed well using forecasted meteorological data and PM24 as input. The enhanced PM 2.5 model was compared with three alternative models, including the basic NLR model, the basic NLR model with a persistence parameter added, and the NLR model with persistence and PM24. The two models that included PM24 were of comparable accuracy. The two models incorporating back-trajectory <span class="hlt">concentrations</span> had lower mean absolute errors and higher rates of detecting unhealthy PM2.5 <span class="hlt">concentrations</span> compared to the other models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70016293','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70016293"><span>Pedologic and climatic controls on Rn-222 <span class="hlt">concentrations</span> in soil <span class="hlt">gas</span>, Denver, Colorado</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Asher-Bolinder, S.; Owen, D.E.; Schumann, R.R.</p> <p>1990-01-01</p> <p>Soil-<span class="hlt">gas</span> radon <span class="hlt">concentrations</span> are controlled seasonally by factors of climate and pedology. In a swelling soil of the semiarid Western United States, soil-<span class="hlt">gas</span> radon <span class="hlt">concentrations</span> at 100 cm depth increase in winter and spring due to increased emanation with higher soil moisture and the capping effect of surface water or ice. Radon <span class="hlt">concentrations</span> in soil drop markedly through the summer and fall. The increased insolation of spring and summer warms and dries the soil, limiting the amount of water that reaches 100 cm. Probable controls on the distribution of uranium within the soil column include its downward leaching, its precipitation or adsorption onto B-horizon clays, concretions, or cement, and the uranium content and mineralogy of the soil's granitic and gneissic precursors. -from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRD..122.7664L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRD..122.7664L"><span>Atmospheric deposition and <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange fluxes of DDT and HCH in the Yangtze River Estuary, East China Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Zhongxia; Lin, Tian; Li, Yuanyuan; Jiang, Yuqing; Guo, Zhigang</p> <p>2017-07-01</p> <p>The Yangtze River Estuary (YRE) is strongly influenced by the Yangtze River and lies on the pathway of the East Asian Monsoon. This study examined atmospheric deposition and <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange fluxes of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) to determine whether the YRE is a sink or source of selected pesticides at the <span class="hlt">air</span>-water interface under the influences of river input and atmospheric transport. The <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange of DDT was characterized by net volatilization with a marked difference in its fluxes between summer (140 ng/m2/d) and the other three seasons (12 ng/m2/d), possibly due to the high surface seawater temperatures and larger riverine input in summer. However, there was no obvious seasonal variation in the atmospheric HCH deposition, and the <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange reached equilibrium because of low HCH levels in the <span class="hlt">air</span> and seawater after the long-term banning of HCH and the degradation. The <span class="hlt">gas</span> exchange flux of HCH was comparable to the dry and wet deposition fluxes at the <span class="hlt">air</span>-water interface. This suggests that the influences from the Yangtze River input and East Asian continental outflow on the fate of HCH in the YRE were limited. The <span class="hlt">gas</span> exchange flux of DDT was about fivefold higher than the total dry and wet deposition fluxes. DDT residues in agricultural soil transported by enhanced riverine runoff were responsible for sustaining such a high net volatilization in summer. Moreover, our results indicated that there were fresh sources of DDT from the local environment to sustain net volatilization throughout the year.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..336a2021S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..336a2021S"><span>Early Leakage Protection System of LPG (Liquefied Petroleum <span class="hlt">Gas</span>) Based on ATMega 16 Microcontroller</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sriwati; Ikhsan Ilahi, Nur; Musrawati; Baco, Syarifuddin; Suyuti'Andani Achmad, Ansar; Umrianah, Ejah</p> <p>2018-04-01</p> <p>LPG (Liquefied Petroleum <span class="hlt">Gas</span>). LPG is a hydrocarbon <span class="hlt">gas</span> production from refineries and <span class="hlt">gas</span> refinery with the major components of propane <span class="hlt">gas</span> (C3H8) and butane (C4H10). Limit flame (Flammable Range) or also called <span class="hlt">gas</span> with <span class="hlt">air</span>. Value Lower Explosive Limit (LEL) is the minimum limit of the <span class="hlt">concentration</span> of fuel vapor in the <span class="hlt">air</span> which if there is no source of fire, the <span class="hlt">gas</span> will be burned. While the value of the Upper Explosive Limit (UEL), which limits the maximum <span class="hlt">concentration</span> of fuel vapor in the <span class="hlt">air</span>, which if no source of fire, the <span class="hlt">gas</span> will be burned. Protection system is a defend mechanism of human, equipment, and buildings around the protected area. Goals to be achieved in this research are to design a protection system against the consequences caused by the leakage of LPG <span class="hlt">gas</span> based on ATmega16 microcontroller. The method used in this research is to reduce the levels of leaked LPG and turned off the power source when the leakage of LPG is on the verge of explosive limit. The design of this protection system works accurately between 200 ppm up to 10000 ppm, which is still below the threshold of explosive. Thus protecting the early result of that will result in the leakage of LPG <span class="hlt">gas</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AtmEn.156...77E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AtmEn.156...77E"><span>Composition and sources of winter haze in the Bakken oil and <span class="hlt">gas</span> extraction region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Evanoski-Cole, A. R.; Gebhart, K. A.; Sive, B. C.; Zhou, Y.; Capps, S. L.; Day, D. E.; Prenni, A. J.; Schurman, M. I.; Sullivan, A. P.; Li, Y.; Hand, J. L.; Schichtel, B. A.; Collett, J. L.</p> <p>2017-05-01</p> <p>In the past decade increased use of hydraulic fracturing and horizontal drilling has dramatically expanded oil and <span class="hlt">gas</span> production in the Bakken formation region. Long term monitoring sites have indicated an increase in wintertime aerosol nitrate and sulfate in this region from particulate matter (PM2.5) measurements collected between 2000 and 2010. No previous intensive <span class="hlt">air</span> quality field campaign has been conducted in this region to assess impacts from oil and <span class="hlt">gas</span> development on regional fine particle <span class="hlt">concentrations</span>. The research presented here investigates wintertime PM2.5 <span class="hlt">concentrations</span> and composition as part of the Bakken <span class="hlt">Air</span> Quality Study (BAQS). Measurements from BAQS took place over two wintertime sampling periods at multiple sites in the United States portion of the Bakken formation and show regionally elevated episodes of PM2.5 during both study periods. Ammonium nitrate was a major contributor to haze episodes. Periods of <span class="hlt">air</span> stagnation or recirculation were associated with rapid increases in PM2.5 <span class="hlt">concentrations</span>. Volatile organic compound (VOC) signatures suggest that <span class="hlt">air</span> masses during these episodes were dominated by emissions from the Bakken region itself. Formation rates of alkyl nitrates from alkanes revealed an <span class="hlt">air</span> mass aging timescale of typically less than a day for periods with elevated PM2.5. A thermodynamic inorganic aerosol model (ISORROPIA) was used to investigate <span class="hlt">gas</span>-particle partitioning and to examine the sensitivity of PM2.5 <span class="hlt">concentrations</span> to aerosol precursor <span class="hlt">concentrations</span>. Formation of ammonium nitrate, the dominant component, was most sensitive to ammonia <span class="hlt">concentrations</span> during winter and to nitric acid <span class="hlt">concentrations</span> during early spring when ammonia availability increases. The availability of excess ammonia suggests capacity for further ammonium nitrate formation if nitrogen oxide emissions increase in the future and lead to additional secondary formation of nitric acid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1197743-using-bayesian-inference-framework-towards-identifying-gas-species-concentration-from-high-temperature-resistive-sensor-array-data','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1197743-using-bayesian-inference-framework-towards-identifying-gas-species-concentration-from-high-temperature-resistive-sensor-array-data"><span>Using Bayesian Inference Framework towards Identifying <span class="hlt">Gas</span> Species and <span class="hlt">Concentration</span> from High Temperature Resistive Sensor Array Data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Liu, Yixin; Zhou, Kai; Lei, Yu</p> <p>2015-01-01</p> <p>High temperature <span class="hlt">gas</span> sensors have been highly demanded for combustion process optimization and toxic emissions control, which usually suffer from poor selectivity. In order to solve this selectivity issue and identify unknown reducing <span class="hlt">gas</span> species (CO, CH 4 , and CH 8 ) and <span class="hlt">concentrations</span>, a high temperature resistive sensor array data set was built in this study based on 5 reported sensors. As each sensor showed specific responses towards different types of reducing <span class="hlt">gas</span> with certain <span class="hlt">concentrations</span>, based on which calibration curves were fitted, providing benchmark sensor array response database, then Bayesian inference framework was utilized to process themore » sensor array data and build a sample selection program to simultaneously identify <span class="hlt">gas</span> species and <span class="hlt">concentration</span>, by formulating proper likelihood between input measured sensor array response pattern of an unknown <span class="hlt">gas</span> and each sampled sensor array response pattern in benchmark database. This algorithm shows good robustness which can accurately identify <span class="hlt">gas</span> species and predict <span class="hlt">gas</span> <span class="hlt">concentration</span> with a small error of less than 10% based on limited amount of experiment data. These features indicate that Bayesian probabilistic approach is a simple and efficient way to process sensor array data, which can significantly reduce the required computational overhead and training data.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AtmEn..87..146W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AtmEn..87..146W"><span>Indoor phthalate <span class="hlt">concentration</span> and exposure in residential and office buildings in Xi'an, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Xinke; Tao, Wei; Xu, Ying; Feng, Jiangtao; Wang, Fenghao</p> <p>2014-04-01</p> <p>Indoor phthalate levels were investigated in 28 buildings, including 14 office and 14 residential buildings in Xi'an, China. Phthalate esters in the <span class="hlt">gas</span>-, particle-, and dust- phase were measured separately. Four phthalates including dimethyl phthalate (DMP), diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP) and di(2-ethylhexyl) phthalate (DEHP) were detected. The detection frequency of DnBP and DEHP was more than 90%. The <span class="hlt">concentrations</span> of total phthalate esters ranged from 0.20 to 8.29 μg m-3 for the <span class="hlt">gas</span>- phase, from 0.09 to 14.77 μg m-3 for the particle- phase and from 123 to 9504 μg g-1 for the dust- phase. The individual phthalate with the highest <span class="hlt">concentrations</span> of 6.17 μg m-3, 7.97 μg m-3 and 7228 μg g-1 respectively for <span class="hlt">gas</span>-, particle- and dust- phase in all investigated rooms is all DiBP. The median <span class="hlt">concentration</span> of the <span class="hlt">gas</span>- and particle-phase DiBP (0.52 and 0.72 μg m-3) and dust-phase DEHP (582 μg g-1) were the highest. It was also found that the average <span class="hlt">concentrations</span> of individual phthalates in residential buildings were often higher than in office buildings, and correlation analysis indicated that DiBP, DnBP and DEHP might come from the same sources. Based on the <span class="hlt">gas</span>- and particle-phase <span class="hlt">concentrations</span> measured, the particle-<span class="hlt">air</span> partition coefficients of phthalates were estimated, and their logarithm values were found to be linearly correlated with the logarithm values of their octanol-<span class="hlt">air</span> partition coefficients. Finally, the total daily exposure to indoor phthalates in <span class="hlt">air</span> and dust was calculated, and ranged from 2.6 μg kg-1 day-1 (for adults) to 7.4 μg kg-1 day-1 (for toddlers).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12406864','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12406864"><span>An investigation of <span class="hlt">air</span> inlet velocity in simulating the dispersion of indoor contaminants via computational fluid dynamics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Eungyoung; Feigley, Charles E; Khan, Jamil</p> <p>2002-11-01</p> <p>Computational fluid dynamics (CFD) is potentially a valuable tool for simulating the dispersion of <span class="hlt">air</span> contaminants in workrooms. However, CFD-estimated airflow and contaminant <span class="hlt">concentration</span> patterns have not always shown good agreement with experimental results. Thus, understanding the factors affecting the accuracy of such simulations is critical for their successful application in occupational hygiene. The purposes of this study were to validate CFD approaches for simulating the dispersion of gases and vapors in an enclosed space at two <span class="hlt">air</span> flow rates and to demonstrate the impact of one important determinant of simulation accuracy. The <span class="hlt">concentration</span> of a tracer <span class="hlt">gas</span>, isobutylene, was measured at 117 points in a rectangular chamber [1 (L) x 0.3 (H) x 0.7 m (W)] using a photoionization analyzer. Chamber <span class="hlt">air</span> flow rates were scaled using geometric and kinematic similarity criteria to represent a full-sized room at two Reynolds numbers (Re = 5 x 10(2) and 5 x 10(3)). Also, CFD simulations were conducted to estimate tracer <span class="hlt">gas</span> <span class="hlt">concentrations</span> throughout the chamber. The simulation results for two treatments of <span class="hlt">air</span> inlet velocity (profiled inlet velocity measured in traverses across the <span class="hlt">air</span> inlet and the assumption that <span class="hlt">air</span> velocity is uniform across the inlet) were compared with experimental observations. The CFD-simulated 3-dimensional distribution of tracer <span class="hlt">gas</span> <span class="hlt">concentration</span> using the profiled inlet velocity showed better agreement qualitatively and quantitatively with measured chamber <span class="hlt">concentration</span>, while the <span class="hlt">concentration</span> estimated using the uniform inlet velocity showed poor agreement for both comparisons. For estimating room <span class="hlt">air</span> contaminant <span class="hlt">concentrations</span> when inlet velocities can be determined, this study suggests that using the inlet velocity distribution to define inlet boundary conditions for CFD simulations can provide more reliable estimates. When the inlet velocity distribution is not known, for instance for prospective design of dilution ventilation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5636194-methane-asphyxia-coal-mine-accident-investigation-distribution-gas','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5636194-methane-asphyxia-coal-mine-accident-investigation-distribution-gas"><span>Methane asphyxia. Coal mine accident investigation of distribution of <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Terazawa, K.; Takatori, T.; Tomii, S.</p> <p>1985-09-01</p> <p>Death from asphyxia due to substitution of <span class="hlt">air</span> by methane <span class="hlt">gas</span> may occur in coal mine by <span class="hlt">gas</span> outburst. In such a case, it is required to determine methane <span class="hlt">gas</span> contents from cadaveric blood and tissues for diagnosing cause of death and estimating conditions of the accident. The methane <span class="hlt">concentration</span> in blood and tissue samples of 22 male victims by a <span class="hlt">gas</span> outburst accident was measured by <span class="hlt">gas</span> chromatography. The level of methane in the cardiac blood was in the range of 6.8-26.8 microliters/g. As a model of <span class="hlt">gas</span> outburst in coal mine, rats were exposed experimentally to various concentrationsmore » of methane. Their course of death and methane distribution in the bodies were observed. From these findings, diagnostic criteria for asphyxia from substitution of <span class="hlt">air</span> by methane are also discussed.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740011790','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740011790"><span>Temperature measurements behind reflected shock waves in <span class="hlt">air</span>. [radiometric measurement of <span class="hlt">gas</span> temperature in self-absorbing <span class="hlt">gas</span> flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bader, J. B.; Nerem, R. M.; Dann, J. B.; Culp, M. A.</p> <p>1972-01-01</p> <p>A radiometric method for the measurement of <span class="hlt">gas</span> temperature in self-absorbing gases has been applied in the study of shock tube generated flows. This method involves making two absolute intensity measurements at identical wavelengths, but for two different pathlengths in the same <span class="hlt">gas</span> sample. Experimental results are presented for reflected shock waves in <span class="hlt">air</span> at conditions corresponding to incident shock velocities from 7 to 10 km/s and an initial driven tube pressure of 1 torr. These results indicate that, with this technique, temperature measurements with an accuracy of + or - 5 percent can be carried out. The results also suggest certain facility related problems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21899099','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21899099"><span>[Hygienic evaluation of direct heating of the <span class="hlt">air</span> delivered to the shaft].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Velichkovskiĭ, B T; Malikov, Iu K; Troitskaia, N A; Belen'kaia, M A; Sergeeva, N V; Shirokova, O V; Kashanskiĭ, S V; Slyshkina, T V; Simonova, O V; Zykova, V A</p> <p>2011-01-01</p> <p>The paper gives the results of exploring a test pre-heating system for the <span class="hlt">air</span> (APHS) delivered to the shaft. The system has been first used in the Urals. The supply <span class="hlt">air</span> is heated by burning natural <span class="hlt">gas</span> in the <span class="hlt">air</span> current. The APHS system with a RG <span class="hlt">air</span> heater (000 "<span class="hlt">Gas</span>-Engineering") is equipped in addition to the existing heaters to enhance heat supply reliability in northern conditions. The data of the studies show that in all periods of the heating season (interseason, moderate frosts, the coldest month), the <span class="hlt">concentrations</span> of hazardous substances, such as nitric oxides, nitric dioxide, sulfur dioxide, carbon dioxide, benz(a)pyrene, solid aerosol in the shaft-delivered <span class="hlt">air</span>, do not exceed those given in the existing regulation provided that the design operating conditions are met. With the maximum <span class="hlt">gas</span> consumption, the coldest month only was marked by the nitric dioxide content being greater than the standard values, causing the maximum projected natural <span class="hlt">gas</span> consumption to be lower in the APHS system. The <span class="hlt">air</span> level of nitric dioxide proved to be a major hygiene indicator while using this <span class="hlt">air</span> heater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70015623','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70015623"><span>Seasonal and geothermal production variations in <span class="hlt">concentrations</span> of He and CO2 in soil gases, Roosevelt Hot Springs Known Geothermal Resource Area, Utah, U.S.A.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hinkle, M.E.</p> <p>1991-01-01</p> <p>To increase understanding of natural variations in soil <span class="hlt">gas</span> <span class="hlt">concentrations</span>, CO2, He, O2 and N2 were measured in soil gases collected regularly for several months from four sites at the Roosevelt Hot Springs Known Geothermal Resource Area, Utah. Soil temperature, <span class="hlt">air</span> temperature, per cent relative humidity, barometric pressure and amounts of rain and snowfall were also monitored to determine the effect of meteorological parameters on <span class="hlt">concentrations</span> of the measured gases. Considerable seasonal variation existed in <span class="hlt">concentrations</span> of CO2 and He. The parameters that most affected the soil-<span class="hlt">gas</span> <span class="hlt">concentrations</span> were soil and <span class="hlt">air</span> temperatures. Moisture from rain and snow probably affected the soil-<span class="hlt">gas</span> <span class="hlt">concentrations</span> also. However, annual variations in meteorological parameters did not appear to affect measurements of anomalous <span class="hlt">concentrations</span> in samples collected within a time period of a few days. Production from some of the geothermal wells probably affected the soil-<span class="hlt">gas</span> <span class="hlt">concentrations</span>. ?? 1990.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24375376','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24375376"><span><span class="hlt">Air</span> conditioning impact on the dynamics of radon and its daughters <span class="hlt">concentration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kozak, Krzysztof; Grządziel, Dominik; Połednik, Bernard; Mazur, Jadwiga; Dudzińska, Marzenna R; Mroczek, Mariusz</p> <p>2014-12-01</p> <p>Radon and its decay products are harmful pollutants present in indoor <span class="hlt">air</span> and are responsible for the majority of the effective dose due to ionising radiation that people are naturally exposed to. The paper presents the results of the series of measurements of radon and its progeny (in unattached and attached fractions) as well as indoor <span class="hlt">air</span> parameters: temperature, relative humidity, number and mass <span class="hlt">concentrations</span> of fine aerosol particles. The measurements were carried out in the auditorium (lecture hall), which is an indoor <span class="hlt">air</span> quality laboratory, in controlled conditions during two periods of time: when <span class="hlt">air</span> conditioning (AC) was switched off (unoccupied auditorium) and when it was switched on (auditorium in normal use). The significant influence of AC and of students' presence on the dynamics of radon and its progeny was confirmed. A decrease in the mean value of radon and its attached progeny was found when AC was working. The mean value of radon equilibrium factor F was also lower when AC was working (0.49) than when it was off (0.61). The linear correlations were found between attached radon progeny <span class="hlt">concentration</span> and particle number and mass <span class="hlt">concentration</span> only when the AC was switched off. This research is being conducted with the aim to study the variability of radon equilibrium factor F which is essential to determine the effective dose due to radon and its progeny inhalation. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=154805&fed_org_id=1253&subject=homeland%20security%20research&view=desc&sortby=pubdateyear&showcriteria=1&count=25&searchall=decontamination%20and%20conference','PESTICIDES'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=154805&fed_org_id=1253&subject=homeland%20security%20research&view=desc&sortby=pubdateyear&showcriteria=1&count=25&searchall=decontamination%20and%20conference"><span>OPTIMIZING SYNTHESIS <span class="hlt">GAS</span> YIELD FROM THE CROSS ...</span></a></p> <p><a target="_blank" href="http://www.epa.gov/pesticides/search.htm">EPA Pesticide Factsheets</a></p> <p></p> <p></p> <p>Symposium Paper Biomass can be gasified to yield synthesis <span class="hlt">gas</span>, tars, and ash. The process is governed by a number of parameters such as the temperature of the gasifying medium (in this case), and the moisture content of the feedstock. Synthesis <span class="hlt">gas</span> from gasifying wood pellets was collected and analyzed as a function of inlet <span class="hlt">air</span> temperature and feedstock moisture content. The <span class="hlt">air</span> was introduced at temperatures ranging from 630 to 730 °C and the moisture content of the feedstock ranged from 8 to 20%. The data collected was used to establish the relationship between the outcome of gasification and these two parameters, and then to determine optimal operating parameters for maximizing the fuel value (maximizing the <span class="hlt">concentrations</span> of flammable gases in the synthesis <span class="hlt">gas</span>) while minimizing the production of gasification tars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790023035','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790023035"><span>Investigation of <span class="hlt">air</span> stream from combustor-liner <span class="hlt">air</span> entry holes, 3</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Aiba, T.; Nakano, T.</p> <p>1979-01-01</p> <p>Jets flowing from <span class="hlt">air</span> entry holes of the combustor liner of a <span class="hlt">gas</span> turbine were investigated. Cold <span class="hlt">air</span> was supplied through the <span class="hlt">air</span> entry holes into the primary hot <span class="hlt">gas</span> flows. The mass flow of the primary hot <span class="hlt">gas</span> and issuing jets was measured, and the behavior of the <span class="hlt">air</span> jets was studied by the measurement of the temperature distribution of the <span class="hlt">gas</span> mixture. The <span class="hlt">air</span> jets flowing from three circular <span class="hlt">air</span> entry holes, single streamwise long holes, and two opposing circular holes, parallel to the primary flow were studied along with the effects of jet and <span class="hlt">gas</span> stream velocities, and of <span class="hlt">gas</span> temperature. The discharge coefficient, the maximum penetration of the jets, the jet flow path, the mixing of the jets, and temperature distribution across the jets were investigated. Empirical expressions which describe the characteristics of the jets under the conditions of the experiments were formulated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4038653','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4038653"><span>Use of dust fall filters as passive samplers for metal <span class="hlt">concentrations</span> in <span class="hlt">air</span> for communities near contaminated mine tailings</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Beamer, P.I.; Sugeng, A. J.; Kelly, M.D.; Lothrop, N.; Klimecki, W.; Wilkinson, S.T.; Loh, M.</p> <p>2014-01-01</p> <p>Mine tailings are a source of metal exposures in many rural communities. Multiple <span class="hlt">air</span> samples are necessary to assess the extent of exposures and factors contributing to these exposures. However, <span class="hlt">air</span> sampling equipment is costly and requires trained personnel to obtain measurements, limiting the number of samples that can be collected. Simple, low-cost methods are needed to allow for increased sample collection. The objective of our study was to assess if dust fall filters can serve as passive <span class="hlt">air</span> samplers and be used to characterize potential exposures in a community near contaminated mine tailings. We placed filters in cylinders, concurrently with active indoor <span class="hlt">air</span> samplers, in 10 occupied homes. We calculated an estimated flow rate by dividing the mass on each dust fall filter by the bulk <span class="hlt">air</span> <span class="hlt">concentration</span> and the sampling duration. The mean estimated flow rate for dust fall filters was significantly different during sampling periods with precipitation. The estimated flow rate was used to estimate metal <span class="hlt">concentration</span> in the <span class="hlt">air</span> of these homes, as well as in 31 additional homes in another rural community impacted by contaminated mine tailings. The estimated <span class="hlt">air</span> <span class="hlt">concentrations</span> had a significant linear association with the measured <span class="hlt">air</span> <span class="hlt">concentrations</span> for beryllium, manganese and arsenic (p<0.05), whose primary source in indoor <span class="hlt">air</span> is resuspended soil from outdoors. In the second rural community, our estimated metal <span class="hlt">concentrations</span> in <span class="hlt">air</span> were comparable to active <span class="hlt">air</span> sampling measurements taken previously. This passive <span class="hlt">air</span> sampler is a simple low-cost method to assess potential exposures near contaminated mining sites. PMID:24469149</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=143123&keyword=predicted+AND+effect+AND+concentration&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=143123&keyword=predicted+AND+effect+AND+concentration&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>A PRINCIPAL COMPONENT ANALYSIS OF THE CLEAN <span class="hlt">AIR</span> STATUS AND TRENDS NETWORK (CASTNET) <span class="hlt">AIR</span> <span class="hlt">CONCENTRATION</span> DATA</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The spatial and temporal variability of ambient <span class="hlt">air</span> <span class="hlt">concentrations</span> of SO<SUB>2</SUB>, SO<SUB>4</SUB><SUP>2-</SUP>, NO<SUB>3</SUB><SUP-</SUP>, HNO<SUB>3</SUB>, and NH<SUB>4</SUB><SUP>+</SUP> obtained from EPA's CASTNet was examined using an objective, statistically based technique...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=311336&Lab=NRMRL&keyword=wind&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=311336&Lab=NRMRL&keyword=wind&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>Analysis of Mobile Source <span class="hlt">Air</span> Toxics (MSATS)–Near-Road VOC and Carbonyl<span class="hlt">Concentrations</span></span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>This presentation examines data from a year-long study of measured near-road mobile source <span class="hlt">air</span> toxic (MSAT) <span class="hlt">concentrations</span> and compares these data with modeled 2005 National <span class="hlt">Air</span> Toxic Assessment (NATA) results. Field study measurements were collected during a field campaign in ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFMOS43A0614I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMOS43A0614I"><span>High <span class="hlt">Concentration</span> of Methane and Magnificent <span class="hlt">gas</span> Plumes Over <span class="hlt">gas</span> Hydrate Field in the Eastern Margin of Japan Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ishida, Y.; Matsumoto, R.; Hiruta, A.; Aoyama, C.; Tomaru, H.; Hiromatsu, M.</p> <p>2005-12-01</p> <p><span class="hlt">Gas</span> hydrates and prominent pockmarks have been observed on the Umitaka Spur in the eastern margin of Japan Sea, at the depth of about 900 m.Magnificent methane plumes, 550 to 600 m high, were detected by echo sounder for fish school, and massive <span class="hlt">gas</span> hydrates were recovered by piston coring during the UT04 cruise of R/V Umitaka-maru (2004). The seawater over this area was collected by CTD and the samples of interstitial waters were extracted from sediment cores by hydraulic squeezer. The ratio of methane to ethane <span class="hlt">concentration</span> (C1/C2) and the isotopic (δ 13C) composition of methane in the plume sites are less than 103 and from -40 to -50 (‰ PDB) respectively, suggesting that the origin of such gases are mostly thermogenic, whereas the gases in the sediments away from plumes are mostly microbial. The seawater samples demonstrated anomalously high <span class="hlt">concentration</span> of methane over the plume sites. Maximum <span class="hlt">concentration</span> is 160nmol/L above the methane plume site. The methane <span class="hlt">concentration</span> values of most samples ranged from 4 to 6nmol/L. When it compared with the Nankai Trough (1 to 4nmol/L), even the base level methane is quite high. Seawater samples collected at the depth of 200 m exhibit sharp anomalies of 16 to 34nmol/L. With the intension to check the possibility of the inflow from the shelf and river waters, we collected surface waters far away from the Umitaka spur. Methane <span class="hlt">concentration</span> was only 7nmol/L. Therefore, we conclude that anomalously high <span class="hlt">concentration</span> at 200 m level over the spur is not likely to be explained by inflow of shelf waters, but also by methane seeps. The temperature of waters are extremely low from 0.25°C to 1.0°C below 300 m, then abruptly increases in shallow waters to about 25°C at surface water. Thus, bottom and intermediate waters are within the stability condition of methane hydrate. Under these conditions, gases from the sea floor would form <span class="hlt">gas</span> hydrate within bottom water mass. <span class="hlt">Gas</span> hydrate crystals would float up shallow to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1172653','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1172653"><span>Experiments to Evaluate and Implement Passive Tracer <span class="hlt">Gas</span> Methods to Measure Ventilation Rates in Homes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lunden, Melissa; Faulkner, David; Heredia, Elizabeth</p> <p>2012-10-01</p> <p>This report documents experiments performed in three homes to assess the methodology used to determine <span class="hlt">air</span> exchange rates using passive tracer techniques. The experiments used four different tracer gases emitted simultaneously but implemented with different spatial coverage in the home. Two different tracer <span class="hlt">gas</span> sampling methods were used. The results characterize the factors of the execution and analysis of the passive tracer technique that affect the uncertainty in the calculated <span class="hlt">air</span> exchange rates. These factors include uncertainties in tracer <span class="hlt">gas</span> emission rates, differences in measured <span class="hlt">concentrations</span> for different tracer gases, temporal and spatial variability of the <span class="hlt">concentrations</span>, the comparison betweenmore » different <span class="hlt">gas</span> sampling methods, and the effect of different ventilation conditions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4849023','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4849023"><span>Changes in <span class="hlt">Air</span> CO2 <span class="hlt">Concentration</span> Differentially Alter Transcript Levels of NtAQP1 and NtPIP2;1 Aquaporin Genes in Tobacco Leaves</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Secchi, Francesca; Schubert, Andrea; Lovisolo, Claudio</p> <p>2016-01-01</p> <p>The aquaporin specific control on water versus carbon pathways in leaves is pivotal in controlling <span class="hlt">gas</span> exchange and leaf hydraulics. We investigated whether Nicotiana tabacum aquaporin 1 (NtAQP1) and Nicotiana tabacum plasma membrane intrinsic protein 2;1 (NtPIP2;1) gene expression varies in tobacco leaves subjected to treatments with different CO2 <span class="hlt">concentrations</span> (ranging from 0 to 800 ppm), inducing changes in photosynthesis, stomatal regulation and water evaporation from the leaf. Changes in <span class="hlt">air</span> CO2 <span class="hlt">concentration</span> ([CO2]) affected net photosynthesis (Pn) and leaf substomatal [CO2] (Ci). Pn was slightly negative at 0 ppm <span class="hlt">air</span> CO2; it was one-third that of ambient controls at 200 ppm, and not different from controls at 800 ppm. Leaves fed with 800 ppm [CO2] showed one-third reduced stomatal conductance (gs) and transpiration (E), and their gs was in turn slightly lower than in 200 ppm– and in 0 ppm–treated leaves. The 800 ppm <span class="hlt">air</span> [CO2] strongly impaired both NtAQP1 and NtPIP2;1 gene expression, whereas 0 ppm <span class="hlt">air</span> [CO2], a <span class="hlt">concentration</span> below any in vivo possible conditions and specifically chosen to maximize the gene expression alteration, increased only the NtAQP1 transcript level. We propose that NtAQP1 expression, an aquaporin devoted to CO2 transport, positively responds to CO2 scarcity in the <span class="hlt">air</span> in the whole range 0–800 ppm. On the contrary, expression of NtPIP2;1, an aquaporin not devoted to CO2 transport, is related to water balance in the leaf, and changes in parallel with gs. These observations fit in a model where upregulation of leaf aquaporins is activated at low Ci, while downregulation occurs when high Ci saturates photosynthesis and causes stomatal closure. PMID:27089333</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1420274','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1420274"><span>Pollutant <span class="hlt">Concentrations</span> and Emission Rates from Scripted Natural <span class="hlt">Gas</span> Cooking Burner Use in Nine Northern California Homes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Singer, Brett C.; Delp, William W.; Lorenzetti, David M.</p> <p></p> <p>METHODS: Combustion pollutant <span class="hlt">concentrations</span> were measured during the scripted operation of natural <span class="hlt">gas</span> cooking burners in nine homes. In addition to a base condition of closed windows, no forced <span class="hlt">air</span> unit (FAU) use, and no mechanical exhaust, additional experiments were conducted while operating an FAU and/or vented range hood. Test homes included a 26m2 two-room apartment, a 134m2 first floor flat, and seven detached homes of 117–226m2. There were four single-story, four two-story and one 1.5 story homes. Cooktop use entailed boiling and simmering activities, using water as a heat sink. Oven and broiler use also were simulated. Time-resolved concentrationsmore » of carbon dioxide (CO2), nitric oxide (NO), nitrogen oxides (NOX), nitrogen dioxide (NO2), particles with diameters of 6 nm or larger (PN), carbon monoxide (CO), and fine particulate matter (PM2.5) were measured in the kitchen (K) and bedroom area (BR) of each home. CO2, NO, NO2, and PN data from sequential experiments were analyzed to quantify the contribution of burner use to the highest 1h and 4h time-integrated <span class="hlt">concentrations</span> in each room. RESULTS: Four of the nine homes had kitchen 1h NO2 exceed the national ambient <span class="hlt">air</span> quality standard (100 ppb). Two other homes had 1h NO2 exceed 50 ppb in the kitchen, and three had 1h NO2 above 50 ppb in the bedroom, suggesting substantial exposures to anyone at home when burners are used for a single substantial event. In all homes, the highest 1h kitchen PN exceeded 2 x105 cm-3-h, and the highest 4h PN exceeded 3 x105 cm-3-hr in all homes. The lowest 1h kitchen/bedroom ratios were 1.3–2.1 for NO in the apartment and two open floor plan homes. The largest K/BR ratios of 1h NO2 were in a two-story 1990s home retrofitted for deep energy savings: ratios in this home were 3.3 to 6.6. Kitchen 1h ratios of NO, NO2 and PN to CO2 were used to calculate fuel normalized emission factors (ng J-1). Range hood use substantially reduced cooking burner pollutant</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6005815-dual-concentric-gas-lift-completion-design-thistle-field','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6005815-dual-concentric-gas-lift-completion-design-thistle-field"><span>Dual <span class="hlt">concentric</span> <span class="hlt">gas</span>-lift completion design for the Thistle field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Moore, P.C.; Adair, P.</p> <p>1991-02-01</p> <p>A unique dual <span class="hlt">concentric</span> <span class="hlt">gas</span>-lift completion was installed in two wells in the thistle field during 1987. This paper outlines the completion concept and design, including vertical-lift performance and tubing movement/stress analysis. Results of field performance after 1 year of production history are presented and compared with predicted values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRD..122.1203W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRD..122.1203W"><span>Low-CCN <span class="hlt">concentration</span> <span class="hlt">air</span> masses over the eastern North Atlantic: Seasonality, meteorology, and drivers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wood, Robert; Stemmler, Jayson D.; Rémillard, Jasmine; Jefferson, Anne</p> <p>2017-01-01</p> <p>A 20 month cloud condensation nucleus <span class="hlt">concentration</span> (NCCN) data set from Graciosa Island (39°N, 28°W) in the remote North Atlantic is used to characterize <span class="hlt">air</span> masses with low cloud condensation nuclei (CCN) <span class="hlt">concentrations</span>. Low-CCN events are defined as 6 h periods with mean NCCN<20 cm-3 (0.1% supersaturation). A total of 47 low-CCN events are identified. Surface, satellite, and reanalysis data are used to explore the meteorological and cloud context for low-CCN <span class="hlt">air</span> masses. Low-CCN events occur in all seasons, but their frequency was 3 times higher in December-May than during June-November. Composites show that many of the low-CCN events had a common meteorological basis that involves southerly low-level flow and rather low wind speeds at Graciosa. Anomalously low pressure is situated to the west of Graciosa during these events, but back trajectories and lagged SLP composites indicate that low-CCN <span class="hlt">air</span> masses often originate as cold <span class="hlt">air</span> outbreaks to the north and west of Graciosa. Low-CCN events were associated with low cloud droplet <span class="hlt">concentrations</span> (Nd) at Graciosa, but liquid water path (LWP) during low-CCN events was not systematically different from that at other times. Satellite Nd and LWP estimates from MODIS collocated with Lagrangian back trajectories show systematically lower Nd and higher LWP several days prior to arrival at Graciosa, consistent with the hypothesis that observed low-CCN <span class="hlt">air</span> masses are often formed by coalescence scavenging in thick warm clouds, often in cold <span class="hlt">air</span> outbreaks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25261866','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25261866"><span>Radon measurement of natural <span class="hlt">gas</span> using alpha scintillation cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kitto, Michael E; Torres, Miguel A; Haines, Douglas K; Semkow, Thomas M</p> <p>2014-12-01</p> <p>Due to their sensitivity and ease of use, alpha-scintillation cells are being increasingly utilized for measurements of radon ((222)Rn) in natural <span class="hlt">gas</span>. Laboratory studies showed an average increase of 7.3% in the measurement efficiency of alpha-scintillation cells when filled with less-dense natural <span class="hlt">gas</span> rather than regular <span class="hlt">air</span>. A theoretical calculation comparing the atomic weight and density of <span class="hlt">air</span> to that of natural <span class="hlt">gas</span> suggests a 6-7% increase in the detection efficiency when measuring radon in the cells. A correction is also applicable when the sampling location and measurement laboratory are at different elevations. These corrections to the measurement efficiency need to be considered in order to derive accurate <span class="hlt">concentrations</span> of radon in natural <span class="hlt">gas</span>. Copyright © 2014 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE10161E..0UW','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE10161E..0UW"><span>Determination of chlorine <span class="hlt">concentration</span> using single temperature modulated semiconductor <span class="hlt">gas</span> sensor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Woźniak, Ł.; Kalinowski, P.; Jasiński, G.; Jasiński, P.</p> <p>2016-11-01</p> <p>A periodic temperature modulation using sinusoidal heater voltage was applied to a commercial SnO2 semiconductor <span class="hlt">gas</span> sensor. Resulting resistance response of the sensor was analyzed using a feature extraction method based on Fast Fourier Transformation (FFT). The amplitudes of the higher harmonics of the FFT from the dynamic nonlinear responses of measured <span class="hlt">gas</span> were further utilized as an input for Artificial Neuron Network (ANN). Determination of the <span class="hlt">concentration</span> of chlorine was performed. Moreover, this work evaluates the sensor performance upon sinusoidal temperature modulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24817348','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24817348"><span>Development and validation of a sensitive thermal desorption-<span class="hlt">gas</span> chromatography-mass spectrometry (TD-GC-MS) method for the determination of phosgene in <span class="hlt">air</span> samples.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Juillet, Y; Dubois, C; Bintein, F; Dissard, J; Bossée, A</p> <p>2014-08-01</p> <p>A new rapid, sensitive and reliable method was developed for the determination of phosgene in <span class="hlt">air</span> samples using thermal desorption (TD) followed by <span class="hlt">gas</span> chromatography-mass spectrometry (GC-MS). The method is based on a fast (10 min) active sampling of only 1 L of <span class="hlt">air</span> onto a Tenax® GR tube doped with 0.5 mL of derivatizing mixture containing dimercaptotoluene and triethylamine in hexane solution. Validation of the TD-GC-MS method showed a low limit of detection (40 ppbv), acceptable repeatability, intermediate fidelity (relative standard deviation within 12 %) and excellent accuracy (>95%). Linearity was demonstrated for two <span class="hlt">concentration</span> ranges (0.04 to 2.5 ppmv and 2.5 to 10 ppmv) owing to variation of derivatization recovery between low and high <span class="hlt">concentration</span> levels. Due to its simple on-site implementation and its close similarity with recommended operating procedure (ROP) for chemical warfare agents vapour sampling, the method is particularly useful in the process of verification of the Chemical Weapons Convention.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AtmEn..41.1343B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AtmEn..41.1343B"><span>Estimated long-term outdoor <span class="hlt">air</span> pollution <span class="hlt">concentrations</span> in a cohort study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beelen, Rob; Hoek, Gerard; Fischer, Paul; Brandt, Piet A. van den; Brunekreef, Bert</p> <p></p> <p>Several recent studies associated long-term exposure to <span class="hlt">air</span> pollution with increased mortality. An ongoing cohort study, the Netherlands Cohort Study on Diet and Cancer (NLCS), was used to study the association between long-term exposure to traffic-related <span class="hlt">air</span> pollution and mortality. Following on a previous exposure assessment study in the NLCS, we improved the exposure assessment methods. Long-term exposure to nitrogen dioxide (NO 2), nitrogen oxide (NO), black smoke (BS), and sulphur dioxide (SO 2) was estimated. Exposure at each home address ( N=21 868) was considered as a function of a regional, an urban and a local component. The regional component was estimated using inverse distance weighed interpolation of measurement data from regional background sites in a national monitoring network. Regression models with urban <span class="hlt">concentrations</span> as dependent variables, and number of inhabitants in different buffers and land use variables, derived with a Geographic Information System (GIS), as predictor variables were used to estimate the urban component. The local component was assessed using a GIS and a digital road network with linked traffic intensities. Traffic intensity on the nearest road and on the nearest major road, and the sum of traffic intensity in a buffer of 100 m around each home address were assessed. Further, a quantitative estimate of the local component was estimated. The regression models to estimate the urban component explained 67%, 46%, 49% and 35% of the variances of NO 2, NO, BS, and SO 2 <span class="hlt">concentrations</span>, respectively. Overall regression models which incorporated the regional, urban and local component explained 84%, 44%, 59% and 56% of the variability in <span class="hlt">concentrations</span> for NO 2, NO, BS and SO 2, respectively. We were able to develop an exposure assessment model using GIS methods and traffic intensities that explained a large part of the variations in outdoor <span class="hlt">air</span> pollution <span class="hlt">concentrations</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhD...50q5202I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhD...50q5202I"><span>Comparative study on extinction process of <span class="hlt">gas</span>-blasted <span class="hlt">air</span> and CO2 arc discharge using two-dimensional electron density imaging sensor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inada, Yuki; Kumada, Akiko; Ikeda, Hisatoshi; Hidaka, Kunihiko; Nakano, Tomoyuki; Murai, Kosuke; Tanaka, Yasunori; Shinkai, Takeshi</p> <p>2017-05-01</p> <p>Shack-Hartmann type laser wavefront sensors were applied to <span class="hlt">gas</span>-blasted arc discharges under current-zero phases, generated in a 50 mm-long interelectrode gap confined by a <span class="hlt">gas</span> flow nozzle, in order to conduct a systematic comparison of electron density decaying processes for two kinds of arc-quenching <span class="hlt">gas</span> media: <span class="hlt">air</span> and \\text{C}{{\\text{O}}2} . The experimental results for the <span class="hlt">air</span> and \\text{C}{{\\text{O}}2} arc plasmas showed that the electron densities and arc diameters became thinner toward the nozzle-throat inlet due to a stronger convection loss in the arc radial direction. In addition, \\text{C}{{\\text{O}}2} had a shorter electron density decaying time constant than <span class="hlt">air</span>, which could be caused by convection loss and turbulent flow of \\text{C}{{\\text{O}}2} stronger than <span class="hlt">air</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A12A..08M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A12A..08M"><span>Tracking Oxidation During Transport of Trace Gases in <span class="hlt">Air</span> from the Northern to Southern Hemisphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Montzka, S. A.; Moore, F. L.; Atlas, E. L.; Parrish, D. D.; Miller, B. R.; Sweeney, C.; McKain, K.; Hall, B. D.; Siso, C.; Crotwell, M.; Hintsa, E. J.; Elkins, J. W.; Blake, D. R.; Barletta, B.; Meinardi, S.; Claxton, T.; Hossaini, R.</p> <p>2017-12-01</p> <p>Trace <span class="hlt">gas</span> mole fractions contain the imprint of recent influences on an <span class="hlt">air</span> mass such as sources, transport, and oxidation. Covariations among the many gases measured from flasks during ATom and HIPPO, and from the ongoing NOAA cooperative <span class="hlt">air</span> sampling program enable recent influences to be identified from a wide range of sources including industrial activity, biomass burning, emissions from wetlands, and uptake by terrestrial ecosystems. In this work we explore the evolution of trace <span class="hlt">gas</span> <span class="hlt">concentrations</span> owing to atmospheric oxidation as <span class="hlt">air</span> masses pass through the tropics, the atmospheric region with the highest <span class="hlt">concentrations</span> of the hydroxyl radical. Variations in C2-C5 hydrocarbon <span class="hlt">concentrations</span> downwind of source regions provide a measure of photochemical ageing in an <span class="hlt">air</span> mass since emission, but they become less useful when tracking photochemical ageing as <span class="hlt">air</span> is transported from the NH into the SH owing to their low mixing ratios, lifetimes that are very short relative to transport times, non-industrial sources in the tropics (e.g., biomass burning), and southern hemispheric sources. Instead, we consider a range of trace gases and trace <span class="hlt">gas</span> pairs that provide a measure of photochemical processing as <span class="hlt">air</span> transits the tropics. To be useful in this analysis, these trace gases would have lifetimes comparable to interhemispheric transport times, emissions arising from only the NH at constant relative magnitudes, and <span class="hlt">concentrations</span> sufficient to allow precise and accurate measurements in both hemispheres. Some anthropogenically-emitted chlorinated hydrocarbons meet these requirements and have been measured during ATom, HIPPO, and from NOAA's ongoing surface sampling efforts. Consideration of these results and their implications for tracking photochemical processing in <span class="hlt">air</span> as it is transported across the tropics will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25019637','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25019637"><span>Augmented switching linear dynamical system model for <span class="hlt">gas</span> <span class="hlt">concentration</span> estimation with MOX sensors in an open sampling system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Di Lello, Enrico; Trincavelli, Marco; Bruyninckx, Herman; De Laet, Tinne</p> <p>2014-07-11</p> <p>In this paper, we introduce a Bayesian time series model approach for <span class="hlt">gas</span> <span class="hlt">concentration</span> estimation using Metal Oxide (MOX) sensors in Open Sampling System (OSS). Our approach focuses on the compensation of the slow response of MOX sensors, while concurrently solving the problem of estimating the <span class="hlt">gas</span> <span class="hlt">concentration</span> in OSS. The proposed Augmented Switching Linear System model allows to include all the sources of uncertainty arising at each step of the problem in a single coherent probabilistic formulation. In particular, the problem of detecting on-line the current sensor dynamical regime and estimating the underlying <span class="hlt">gas</span> <span class="hlt">concentration</span> under environmental disturbances and noisy measurements is formulated and solved as a statistical inference problem. Our model improves, with respect to the state of the art, where system modeling approaches have been already introduced, but only provided an indirect relative measures proportional to the <span class="hlt">gas</span> <span class="hlt">concentration</span> and the problem of modeling uncertainty was ignored. Our approach is validated experimentally and the performances in terms of speed of and quality of the <span class="hlt">gas</span> <span class="hlt">concentration</span> estimation are compared with the ones obtained using a photo-ionization detector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.5784F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.5784F"><span>Short-term Rn-222 <span class="hlt">concentration</span> changes in underground spaces with limited <span class="hlt">air</span> exchange</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fijałkowska-Lichwa, Lidia; Przylibski, Tadeusz A.</p> <p>2010-05-01</p> <p>Authors conducted research on radon <span class="hlt">concentration</span> in two underground structures located in the vicinity of Kletno (Sudety Mts., SW Poland), which are accessible for visitors. One of these structures is Niedźwiedzia (Bear) Cave, and the second one is the part of former uranium mine - Fluorite Adit. Both selected underground structures are characterized by almost constant temperature, changing within the range from +5 to +7° C and also constant relative humidity, close to 100%. Both these parameters testify that <span class="hlt">air</span> exchange with the atmosphere is very limited. <span class="hlt">Air</span> exchange is limited particularly in Niedźwiedzia Cave, which microclimate is protected i.e. by applying of locks at the entrance and exit of tourist route. The measurements were conducted between 16.05.2008. and 15.11.2009., by the use of a new Polish equipment - SRDN-3 devices with semiconductor detector. SRDN-3 device records every hour radon <span class="hlt">concentration</span> as well as atmospheric parameters - relative humidity and temperature. At the same time authors conducted measurements of basic parameters in the open atmosphere close to Niedźwiedzia Cave. Obtained results of atmospheric parameters measurements may be used for both underground structures; because they are located within the distance of about 1 km. Atmospheric parameters were measured by the use of automatic weather station VantagePro2. On the base of conducted research authors corroborate, that the differences of radon <span class="hlt">concentration</span> in both underground structures reach three orders of magnitude during a year. In Niedźwiedzia Cave these values are in the range from below 88 Bq/m3 (detection limit of the SRDN-3 device) up to 12 kBq/m3. Related values in Fluorite Adit are between < 88 Bq/m3 and 35 kBq/m3. It was observed also the different course of daily radon <span class="hlt">concentration</span> changes in both structures. Additionally, authors registered that daily course of radon <span class="hlt">concentration</span> changes differs due to season of the year. Such changes are observed in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160005390','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160005390"><span>Portable Cathode-<span class="hlt">Air</span> Vapor-Feed Electrochemical Medical Oxygen <span class="hlt">Concentrator</span> (OC)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Balasubramanian, Ashwin</p> <p>2015-01-01</p> <p>Missions on the International Space Station and future space exploration will present significant challenges to crew health care capabilities, particularly in the efficient utilization of onboard oxygen resources. Exploration vehicles will require lightweight, compact, and portable oxygen <span class="hlt">concentrators</span> that can provide medical-grade oxygen from the ambient cabin <span class="hlt">air</span>. Current pressure-swing adsorption OCs are heavy and bulky, require significant start-up periods, operate in narrow temperature ranges, and require a liquid water feed. Lynntech, Inc., has developed an electrochemical OC that operates with a cathode-<span class="hlt">air</span> vapor feed, eliminating the need for a bulky onboard water supply. Lynntech's OC is smaller and lighter than conventional pressure-swing OCs, is capable of instant start-up, and operates over a temperature range of 5-80 C. Accomplished through a unique nanocomposite proton exchange membrane and catalyst technology, the unit delivers 4 standard liters per minute of humidified oxygen at 60 percent <span class="hlt">concentration</span>. The technology enables both ambient-pressure operating devices for portable applications and pressurized (up to 3,600 psi) OC devices for stationary applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.830a2060P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.830a2060P"><span>Propagation of atmospheric pressure helium plasma jet into ambient <span class="hlt">air</span> at laminar <span class="hlt">gas</span> flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pinchuk, M.; Stepanova, O.; Kurakina, N.; Spodobin, V.</p> <p>2017-05-01</p> <p>The formation of an atmospheric pressure plasma jet (APPJ) in a <span class="hlt">gas</span> flow passing through the discharge gap depends on both <span class="hlt">gas</span>-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided <span class="hlt">gas</span> passing through it, served as a plasma source. The transition of the laminar regime of <span class="hlt">gas</span> flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding <span class="hlt">gas</span> outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate <span class="hlt">gas</span> dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient <span class="hlt">air</span> in a helium flow, which is established along the direction of <span class="hlt">gas</span> flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPSJ...86l4502Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPSJ...86l4502Y"><span>Estimation of Flow Channel Parameters for Flowing <span class="hlt">Gas</span> Mixed with <span class="hlt">Air</span> in Atmospheric-pressure Plasma Jets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yambe, Kiyoyuki; Saito, Hidetoshi</p> <p>2017-12-01</p> <p>When the working <span class="hlt">gas</span> of an atmospheric-pressure non-equilibrium (cold) plasma flows into free space, the diameter of the resulting flow channel changes continuously. The shape of the channel is observed through the light emitted by the working <span class="hlt">gas</span> of the atmospheric-pressure plasma. When the plasma jet forms a conical shape, the diameter of the cylindrical shape, which approximates the conical shape, defines the diameter of the flow channel. When the working <span class="hlt">gas</span> flows into the atmosphere from the inside of a quartz tube, the <span class="hlt">gas</span> mixes with <span class="hlt">air</span>. The molar ratio of the working <span class="hlt">gas</span> and <span class="hlt">air</span> is estimated from the corresponding volume ratio through the relationship between the diameter of the cylindrical plasma channel and the inner diameter of the quartz tube. The Reynolds number is calculated from the kinematic viscosity of the mixed <span class="hlt">gas</span> and the molar ratio. The <span class="hlt">gas</span> flow rates for the upper limit of laminar flow and the lower limit of turbulent flow are determined by the corresponding Reynolds numbers estimated from the molar ratio. It is confirmed that the plasma jet length and the internal plasma length associated with strong light emission increase with the increasing <span class="hlt">gas</span> flow rate until the rate for the upper limit of laminar flow and the lower limit of turbulent flow, respectively. Thus, we are able to explain the increasing trend in the plasma lengths with the diameter of the flow channel and the molar ratio by using the cylindrical approximation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70030694','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70030694"><span>Estimates of in situ <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span> from resistivity monitoring of <span class="hlt">gas</span> hydrate bearing sediments during temperature equilibration</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Riedel, M.; Long, P.E.; Collett, T.S.</p> <p>2006-01-01</p> <p>As part of Ocean Drilling Program Leg 204 at southern Hydrate Ridge off Oregon we have monitored changes in sediment electrical resistivity during controlled <span class="hlt">gas</span> hydrate dissociation experiments. Two cores were used, each filled with <span class="hlt">gas</span> hydrate bearing sediments (predominantly mud/silty mud). One core was from Site 1249 (1249F-9H3), 42.1 m below seafloor (mbsf) and the other from Site 1248 (1248C-4X1), 28.8 mbsf. At Site 1247, a third experiment was conducted on a core without <span class="hlt">gas</span> hydrate (1247B-2H1, 3.6 mbsf). First, the cores were imaged using an infra-red (IR) camera upon recovery to map the <span class="hlt">gas</span> hydrate occurrence through dissociation cooling. Over a period of several hours, successive runs on the multi-sensor track (includes sensors for P-wave velocity, resistivity, magnetic susceptibility and gamma-ray density) were carried out complemented by X-ray imaging on core 1249F-9H3. After complete equilibration to room temperature (17-18??C) and complete <span class="hlt">gas</span> hydrate dissociation, the final measurement of electrical resistivity was used to calculate pore-water resistivity and salinities. The calculated pore-water freshening after dissociation is equivalent to a <span class="hlt">gas</span> hydrate <span class="hlt">concentration</span> in situ of 35-70% along core 1249F-9H3 and 20-35% for core 1248C-4X1 assuming seawater salinity of in situ pore fluid. Detailed analysis of the IR scan, X-ray images and split-core photographs showed the hydrate mainly occurred disseminated throughout the core. Additionally, in core 1249F-9H3, a single hydrate filled vein, approximately 10 cm long and dipping at about 65??, was identified. Analyses of the logging-while-drilling (LWD) resistivity data revealed a structural dip of 40-80?? in the interval between 40 and 44 mbsf. We further analyzed all resistivity data measured on the recovered core during Leg 204. Generally poor data quality due to <span class="hlt">gas</span> cracks allowed analyses to be carried out only at selected intervals at Sites 1244, 1245, 1246, 1247, 1248, 1249, and 1252. With a few</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28898956','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28898956"><span>Long short-term memory neural network for <span class="hlt">air</span> pollutant <span class="hlt">concentration</span> predictions: Method development and evaluation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Xiang; Peng, Ling; Yao, Xiaojing; Cui, Shaolong; Hu, Yuan; You, Chengzeng; Chi, Tianhe</p> <p>2017-12-01</p> <p><span class="hlt">Air</span> pollutant <span class="hlt">concentration</span> forecasting is an effective method of protecting public health by providing an early warning against harmful <span class="hlt">air</span> pollutants. However, existing methods of <span class="hlt">air</span> pollutant <span class="hlt">concentration</span> prediction fail to effectively model long-term dependencies, and most neglect spatial correlations. In this paper, a novel long short-term memory neural network extended (LSTME) model that inherently considers spatiotemporal correlations is proposed for <span class="hlt">air</span> pollutant <span class="hlt">concentration</span> prediction. Long short-term memory (LSTM) layers were used to automatically extract inherent useful features from historical <span class="hlt">air</span> pollutant data, and auxiliary data, including meteorological data and time stamp data, were merged into the proposed model to enhance the performance. Hourly PM 2.5 (particulate matter with an aerodynamic diameter less than or equal to 2.5 μm) <span class="hlt">concentration</span> data collected at 12 <span class="hlt">air</span> quality monitoring stations in Beijing City from Jan/01/2014 to May/28/2016 were used to validate the effectiveness of the proposed LSTME model. Experiments were performed using the spatiotemporal deep learning (STDL) model, the time delay neural network (TDNN) model, the autoregressive moving average (ARMA) model, the support vector regression (SVR) model, and the traditional LSTM NN model, and a comparison of the results demonstrated that the LSTME model is superior to the other statistics-based models. Additionally, the use of auxiliary data improved model performance. For the one-hour prediction tasks, the proposed model performed well and exhibited a mean absolute percentage error (MAPE) of 11.93%. In addition, we conducted multiscale predictions over different time spans and achieved satisfactory performance, even for 13-24 h prediction tasks (MAPE = 31.47%). Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830046452&hterms=water+gas+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dwater%2Bgas%2Bexchange','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830046452&hterms=water+gas+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dwater%2Bgas%2Bexchange"><span>Methane flux across the <span class="hlt">air</span>-water interface - <span class="hlt">Air</span> velocity effects</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sebacher, D. I.; Harriss, R. C.; Bartlett, K. B.</p> <p>1983-01-01</p> <p>Methane loss to the atmosphere from flooded wetlands is influenced by the degree of supersaturation and wind stress at the water surface. Measurements in freshwater ponds in the St. Marks Wildlife Refuge, Florida, demonstrated that for the combined variability of CH4 <span class="hlt">concentrations</span> in surface water and <span class="hlt">air</span> velocity over the water surface, CH4 flux varied from 0.01 to 1.22 g/sq m/day. The liquid exchange coefficient for a two-layer model of the <span class="hlt">gas</span>-liquid interface was calculated as 1.7 cm/h for CH4 at <span class="hlt">air</span> velocity of zero and as 1.1 + 1.2 v to the 1.96th power cm/h for <span class="hlt">air</span> velocities from 1.4 to 3.5 m/s and water temperatures of 20 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28110005','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28110005"><span><span class="hlt">Concentrations</span>, sources and human health risk of inhalation exposure to <span class="hlt">air</span> toxics in Edmonton, Canada.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bari, Md Aynul; Kindzierski, Warren B</p> <p>2017-04-01</p> <p>With concern about levels of <span class="hlt">air</span> pollutants in recent years in the Capital Region of Alberta, an investigation of ambient <span class="hlt">concentrations</span>, sources and potential human health risk of hazardous <span class="hlt">air</span> pollutants (HAPs) or <span class="hlt">air</span> toxics was undertaken in the City of Edmonton over a 5-year period (2009-2013). Mean <span class="hlt">concentrations</span> of individual HAPs in ambient <span class="hlt">air</span> including volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and trace metals ranged from 0.04 to 1.73 μg/m 3 , 0.01-0.54 ng/m 3 , and 0.05-3.58 ng/m 3 , respectively. <span class="hlt">Concentrations</span> of benzene, naphthalene, benzo(a)pyrene (BaP), arsenic, manganese and nickel were far below respective annual Alberta Ambient <span class="hlt">Air</span> Quality Objectives. Carcinogenic and non-carcinogenic risk of <span class="hlt">air</span> toxics were also compared with risk levels recommended by regulatory agencies. Positive matrix factorization identified six <span class="hlt">air</span> toxics sources with traffic as the dominant contributor to total HAPs (4.33 μg/m 3 , 42%), followed by background/secondary organic aerosol (SOA) (1.92 μg/m 3 , 25%), fossil fuel combustion (0.92 μg/m 3 , 11%). On high particulate <span class="hlt">air</span> pollution event days, local traffic was identified as the major contributor to total HAPs compared to background/SOA and fossil fuel combustion. Carcinogenic risk values of traffic, background/SOA and metals industry emissions were above the USEPA acceptable level (1 × 10 -6 ), but below a tolerable risk (1 × 10 -4 ) and Alberta benchmark (1 × 10 -5 ). These findings offer useful preliminary information about current ambient <span class="hlt">air</span> toxics levels, dominant sources and their potential risk to public health; and this information can support policy makers in the development of appropriate control strategies if required. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/875288','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/875288"><span>Electrochemical separation and <span class="hlt">concentration</span> of hydrogen sulfide from <span class="hlt">gas</span> mixtures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Winnick, Jack; Sather, Norman F.; Huang, Hann S.</p> <p>1984-10-30</p> <p>A method of removing sulfur oxides of H.sub.2 S from high temperature <span class="hlt">gas</span> mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The <span class="hlt">gas</span> mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4 -- or, in the case of H.sub.2 S, to S--. The anions migrate to the anode where they are converted to a stable gaseous form at much greater <span class="hlt">concentration</span> levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing <span class="hlt">gas</span> such as hydrogen past the anode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1176686','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1176686"><span>ELECTROCHEMICAL SEPARATION AND <span class="hlt">CONCENTRATION</span> OF HYDROGEN SULFIDE FROM <span class="hlt">GAS</span> MIXTURES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Winnick, Jack; Sather, Norman F.; Huang, Hann S.</p> <p>1984-10-30</p> <p>A method of removing sulfur oxides of H.sub.2 S from high temperature <span class="hlt">gas</span> mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The <span class="hlt">gas</span> mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4 -- or, in the case of H.sub.2 S, to S--. The anions migrate to the anode where they are converted to a stable gaseous form at much greater <span class="hlt">concentration</span> levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing <span class="hlt">gas</span> such as hydrogen past the anode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/864356','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/864356"><span>Primary zone <span class="hlt">air</span> proportioner</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Cleary, Edward N. G.</p> <p>1982-10-12</p> <p>An <span class="hlt">air</span> proportioner is provided for a liquid hydrocarbon fueled <span class="hlt">gas</span> turbine of the type which is convertible to oil <span class="hlt">gas</span> fuel and to coal <span class="hlt">gas</span> fuel. The turbine includes a shell for enclosing the turbine, an <span class="hlt">air</span> duct for venting <span class="hlt">air</span> in said shell to a gasifier, and a fuel injector for injecting gasified fuel into the turbine. The <span class="hlt">air</span> proportioner comprises a second <span class="hlt">air</span> duct for venting <span class="hlt">air</span> from the <span class="hlt">air</span> duct for mixing with fuel from the gasifier. The <span class="hlt">air</span> can be directly injected into the <span class="hlt">gas</span> combustion basket along with the fuel from the injector or premixed with fuel from the gasifier prior to injection by the fuel injector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....17.9019B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....17.9019B"><span>Estimation of bubble-mediated <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange from concurrent DMS and CO2 transfer velocities at intermediate-high wind speeds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bell, Thomas G.; Landwehr, Sebastian; Miller, Scott D.; de Bruyn, Warren J.; Callaghan, Adrian H.; Scanlon, Brian; Ward, Brian; Yang, Mingxi; Saltzman, Eric S.</p> <p>2017-07-01</p> <p>Simultaneous <span class="hlt">air</span>-sea fluxes and <span class="hlt">concentration</span> differences of dimethylsulfide (DMS) and carbon dioxide (CO2) were measured during a summertime North Atlantic cruise in 2011. This data set reveals significant differences between the <span class="hlt">gas</span> transfer velocities of these two gases (Δkw) over a range of wind speeds up to 21 m s-1. These differences occur at and above the approximate wind speed threshold when waves begin breaking. Whitecap fraction (a proxy for bubbles) was also measured and has a positive relationship with Δkw, consistent with enhanced bubble-mediated transfer of the less soluble CO2 relative to that of the more soluble DMS. However, the correlation of Δkw with whitecap fraction is no stronger than with wind speed. Models used to estimate bubble-mediated transfer from in situ whitecap fraction underpredict the observations, particularly at intermediate wind speeds. Examining the differences between <span class="hlt">gas</span> transfer velocities of gases with different solubilities is a useful way to detect the impact of bubble-mediated exchange. More simultaneous <span class="hlt">gas</span> transfer measurements of different solubility gases across a wide range of oceanic conditions are needed to understand the factors controlling the magnitude and scaling of bubble-mediated <span class="hlt">gas</span> exchange.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1434521','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1434521"><span>Staged fuel and <span class="hlt">air</span> injection in combustion systems of <span class="hlt">gas</span> turbines</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hughes, Michael John; Berry, Jonathan Dwight</p> <p></p> <p>A <span class="hlt">gas</span> turbine including a working fluid flowpath extending aftward from a forward injector in a combustor. The combustor may include an inner radial wall, an outer radial wall, and, therebetween, a flow annulus, and a third radial wall formed about the outer radial wall that forms an outer flow annulus. A staged injector may intersect the flow annulus so to attain an injection point within the working fluid flowpath by which aftward and forward annulus sections are defined. <span class="hlt">Air</span> directing structure may include an aftward intake section corresponding to the aftward annulus section and a forward intake section correspondingmore » to the forward annulus section. The <span class="hlt">air</span> directing structure may include a switchback coolant flowpath to direct <span class="hlt">air</span> from the compressor discharge cavity to the staged injector. The switchback coolant flowpath may include an upstream section through the flow annulus, and a downstream section through the outer flow annulus.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AtmEn..43.4577M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AtmEn..43.4577M"><span><span class="hlt">Concentrations</span> and elemental composition of particulate matter in the Buenos <span class="hlt">Aires</span> underground system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murruni, L. G.; Solanes, V.; Debray, M.; Kreiner, A. J.; Davidson, J.; Davidson, M.; Vázquez, M.; Ozafrán, M.</p> <p></p> <p>Total suspended particulate (TSP) samples have been collected at six stations in the C and B lines of the Buenos <span class="hlt">Aires</span> underground system and, almost simultaneously, at six ground level sites outside and nearby the corresponding underground stations, in the Oct 2005/Oct 2006 period. All these samples were analyzed for mass and elemental Fe, Cu, and Zn <span class="hlt">concentrations</span> by using the Particle Induced X-ray Emission (PIXE) technique. Mostly, TSP <span class="hlt">concentrations</span> were found to be between 152 μg m -3 (25% percentile) and 270 μg m -3 (75% percentile) in the platform of the stations, while those in outside ambient <span class="hlt">air</span> oscillated from 55 μg m -3 (25% percentile) to 137 μg m -3 (75% percentile). Moreover, experimental results indicate that TSP levels are comparable to those measured for other underground systems worldwide. Statistical results demonstrate that subway TSP levels are about 3 times larger on average than those for urban ambient <span class="hlt">air</span>. The TSP levels inside stations and outdoors are poorly correlated, indicating that TSP levels in the metro system are mainly influenced by internal sources. Regarding metal <span class="hlt">concentrations</span>, the most enriched element in TSP samples was Fe, the levels of which ranged from 36 (25% percentile) to 86 μg m -3 (75% percentile) in Line C stations, while in Line B ones they varied between 8 μg m -3 (25% percentile) and 46 μg m -3 (75% percentile). As a comparison, Fe <span class="hlt">concentrations</span> in ambient <span class="hlt">air</span> oscillated between 0.7 μg m -3 (25% percentile) and 1.2 μg m -3 (75% percentile). Other enriched elements include Cu and Zn. With regard to their sources, Fe and Cu have been related to processes taking place inside the subway system, while Zn has been associated with outdoor vehicular traffic. Additionally, concerns about possible health implications based on comparisons to various indoor <span class="hlt">air</span> quality limits and available toxicological information are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23923426','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23923426"><span>Effect of central ventilation and <span class="hlt">air</span> conditioner system on the <span class="hlt">concentration</span> and health risk from airborne polycyclic aromatic hydrocarbons.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lv, Jinze; Zhu, Lizhong</p> <p>2013-03-01</p> <p>Central ventilation and <span class="hlt">air</span> conditioner systems are widely utilized nowadays in public places for <span class="hlt">air</span> exchange and temperature control, which significantly influences the transfer of pollutants between indoors and outdoors. To study the effect of central ventilation and <span class="hlt">air</span> conditioner systems on the <span class="hlt">concentration</span> and health risk from airborne pollutants, a spatial and temporal survey was carried out using polycyclic aromatic hydrocarbons (PAHs) as agent pollutants. During the period when the central ventilation system operated without <span class="hlt">air</span> conditioning (AC-off period), <span class="hlt">concentrations</span> of 2-4 ring PAHs in the model supermarket were dominated by outdoor levels, due to the good linearity between indoor <span class="hlt">air</span> and outdoor <span class="hlt">air</span> (r(p) > 0.769, p < 0.05), and the slopes (1.2-4.54) indicated that ventilating like the model supermarket increased the potential health risks from low molecular weight PAHs. During the period when the central ventilation and <span class="hlt">air</span> conditioner systems were working simultaneously (AC-on period), although the total levels of PAHs were increased, the <span class="hlt">concentrations</span> and percentage of the particulate PAHs indoors declined significantly. The BaP equivalency (BaPeq) <span class="hlt">concentration</span> indicated that utilization of <span class="hlt">air</span> conditioning reduced the health risks from PAHs in the model supermarket.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013BGeo...10.1379C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013BGeo...10.1379C"><span>Technical Note: A simple method for <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange measurements in mesocosms and its application in carbon budgeting</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Czerny, J.; Schulz, K. G.; Ludwig, A.; Riebesell, U.</p> <p>2013-03-01</p> <p>Mesocosms as large experimental units provide the opportunity to perform elemental mass balance calculations, e.g. to derive net biological turnover rates. However, the system is in most cases not closed at the water surface and gases exchange with the atmosphere. Previous attempts to budget carbon pools in mesocosms relied on educated guesses concerning the exchange of CO2 with the atmosphere. Here, we present a simple method for precise determination of <span class="hlt">air</span>-sea <span class="hlt">gas</span> exchange in mesocosms using N2O as a deliberate tracer. Beside the application for carbon budgeting, transfer velocities can be used to calculate exchange rates of any <span class="hlt">gas</span> of known <span class="hlt">concentration</span>, e.g. to calculate aquatic production rates of climate relevant trace gases. Using an arctic KOSMOS (Kiel Off Shore Mesocosms for future Ocean Simulation) experiment as an exemplary dataset, it is shown that the presented method improves accuracy of carbon budget estimates substantially. Methodology of manipulation, measurement, data processing and conversion to CO2 fluxes are explained. A theoretical discussion of prerequisites for precise <span class="hlt">gas</span> exchange measurements provides a guideline for the applicability of the method under various experimental conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6730304-concentrations-methoxyflurane-nitrous-oxide-veterinary-operating-rooms','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6730304-concentrations-methoxyflurane-nitrous-oxide-veterinary-operating-rooms"><span><span class="hlt">Concentrations</span> of methoxyflurane and nitrous oxide in veterinary operating rooms</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Ward, G.S.; Byland, R.R.</p> <p>1982-02-01</p> <p>The surgical rooms of 14 private veterinary practices were monitored to determined methoxyflurane (MOF) <span class="hlt">concentrations</span> during surgical procedure under routine working conditions. The average room volume for these 14 rooms was 29 m3. The average MOF value for all rooms was 2.3 ppm, with a range of 0.7 to 7.4 ppm. Four of the 14 rooms exceeded the maximum recommended <span class="hlt">concentration</span> of 2 ppm. Six rooms which had 6 or more <span class="hlt">air</span> changes/hr averaged 1.1 ppm, whereas 8 rooms with less than 6 measurable <span class="hlt">air</span> changes/hr averaged 3.2 ppm. Operating rooms that had oxygen flows of more than 1,000 cm3/minmore » averaged 4.4 ppm, whereas those with flows of less than 1,000 cm3/min averaged 1.5 ppm. The average time spent during a surgical procedure using MOF, for all 14 facilities, was 2 hours. Nitrous oxide (N/sub 2/O) <span class="hlt">concentrations</span> were determined in 4 veterinary surgical rooms. The average N/sub 2/O <span class="hlt">concentration</span> for 3 rooms without waste anesthetic <span class="hlt">gas</span> scavenging was 138 ppm. <span class="hlt">Concentration</span> of N/sub 2/O in the waste anesthetic <span class="hlt">gas</span>-scavenged surgical room was 14 ppm, which was below the maximum recommended <span class="hlt">concentration</span> of 25 ppm.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18082950','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18082950"><span>Temporal variability of benzene <span class="hlt">concentration</span> in the ambient <span class="hlt">air</span> of Delhi: a comparative assessment of pre- and post-CNG periods.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Khillare, P S; Hoque, Raza Rafiqul; Shridhar, Vijay; Agarwal, Tripti; Balachandran, S</p> <p>2008-06-15</p> <p>CNG (compressed natural <span class="hlt">gas</span>) was fully implemented in public transport system in Delhi in December 2002. The study assesses the benzene <span class="hlt">concentration</span> trends at two busy traffic intersections and a background site in Delhi, India. Monitoring was done for two different time periods viz; in the year 2001-2002 (pre-CNG) and two winter months (January and February) of the year 2007 (post-CNG) to assess the impact of various policy measures adopted by the government of Delhi to improve the <span class="hlt">air</span> quality in the city. Annual average benzene <span class="hlt">concentration</span> for the pre-CNG period was found to be 86.47+/-53.24 microg m(-3). Average benzene <span class="hlt">concentrations</span> for the winter months (January-February) of pre- and post-CNG periods were 116.32+/-51.65 microg m(-3) and 187.49+/-22.50 microg m(-3), respectively. Enhanced values could be solely attributed to the increase in the vehicular population from 3.5 million in the year 2001-2002 to approximately 5.1 millions in the year 2007.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1167028','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1167028"><span>Ambient <span class="hlt">air</span> cooling arrangement having a pre-swirler for <span class="hlt">gas</span> turbine engine blade cooling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Lee, Ching-Pang; Tham, Kok-Mun; Schroeder, Eric; Meeroff, Jamie; Miller, Jr., Samuel R; Marra, John J</p> <p>2015-01-06</p> <p>A <span class="hlt">gas</span> turbine engine including: an ambient-<span class="hlt">air</span> cooling circuit (10) having a cooling channel (26) disposed in a turbine blade (22) and in fluid communication with a source (12) of ambient <span class="hlt">air</span>: and an pre-swirler (18), the pre-swirler having: an inner shroud (38); an outer shroud (56); and a plurality of guide vanes (42), each spanning from the inner shroud to the outer shroud. Circumferentially adjacent guide vanes (46, 48) define respective nozzles (44) there between. Forces created by a rotation of the turbine blade motivate ambient <span class="hlt">air</span> through the cooling circuit. The pre-swirler is configured to impart swirl to ambient <span class="hlt">air</span> drawn through the nozzles and to direct the swirled ambient <span class="hlt">air</span> toward a base of the turbine blade. The end walls (50, 54) of the pre-swirler may be contoured.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24215174','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24215174"><span>Exposure of pregnant women to cookstove-related household <span class="hlt">air</span> pollution in urban and periurban Trujillo, Peru.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>St Helen, Gideon; Aguilar-Villalobos, Manuel; Adetona, Olorunfemi; Cassidy, Brandon; Bayer, Charlene W; Hendry, Robert; Hall, Daniel B; Naeher, Luke P</p> <p>2015-01-01</p> <p>Although evidence suggests associations between maternal exposure to <span class="hlt">air</span> pollution and adverse birth outcomes, pregnant women's exposure to household <span class="hlt">air</span> pollution in developing countries is understudied. Personal exposures of pregnant women (N = 100) in Trujillo, Peru, to <span class="hlt">air</span> pollutants and their indoor <span class="hlt">concentrations</span> were measured. The effects of stove-use-related characteristics and ambient <span class="hlt">air</span> pollution on exposure were determined using mixed-effects models. Significant differences in 48-hour kitchen <span class="hlt">concentrations</span> of particulate matter (PM2.5), carbon monoxide (CO), and nitrogen dioxide (NO2) <span class="hlt">concentrations</span> were observed across fuel types (p < 0.05). Geometric mean PM2.5 <span class="hlt">concentrations</span> where 112 μg/m(3) (confidence limits [CLs]: 52, 242 μg/m(3)) and 42 μg/m(3) (21, 82 μg/m(3)) in homes where wood and <span class="hlt">gas</span> were used, respectively. PM2.5 exposure was at levels that recent exposure-response analyses suggest may not result in substantial reduction in health risks even in homes where cleaner burning <span class="hlt">gas</span> stoves were used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914393L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914393L"><span>Direct monitoring of wind-induced pressure-pumping on <span class="hlt">gas</span> transport in soil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laemmel, Thomas; Mohr, Manuel; Schindler, Dirk; Schack-Kirchner, Helmer; Maier, Martin</p> <p>2017-04-01</p> <p><span class="hlt">Gas</span> exchange between soil and atmosphere is important for the biogeochemistry of soils and is commonly assumed to be governed by molecular diffusion. Yet a few previous field studies identified other <span class="hlt">gas</span> transport processes such as wind-induced pressure-pumping to enhance soil-atmosphere fluxes significantly. However, since these wind-induced non-diffusive <span class="hlt">gas</span> transport processes in soil often occur intermittently, the quantification of their contribution to soil <span class="hlt">gas</span> emissions is challenging. To quantify the effects of wind-induced pressure-pumping on soil <span class="hlt">gas</span> transport, we developed a method for in situ monitoring of soil <span class="hlt">gas</span> transport. The method includes the use of Helium (He) as a tracer <span class="hlt">gas</span> which was continuously injected into the soil. The resulting He steady-state <span class="hlt">concentration</span> profile was monitored. <span class="hlt">Gas</span> transport parameters of the soil were inversely modelled. We used our method during a field campaign in a well-aerated forest soil over three months. During periods of low wind speed, soil <span class="hlt">gas</span> transport was modelled assuming diffusion as transport process. During periods of high wind speed, the previously steady diffusive He <span class="hlt">concentration</span> profile showed temporary <span class="hlt">concentration</span> decreases in the topsoil, indicating an increase of the effective <span class="hlt">gas</span> transport rate in the topsoil up to 30%. The enhancement of effective topsoil soil <span class="hlt">gas</span> diffusivity resulted from wind-induced <span class="hlt">air</span> pressure fluctuations which are referred to as pressure-pumping. These <span class="hlt">air</span> pressure fluctuations had frequencies between 0.1 and 0.01 Hz and amplitudes up to 10 Pa and occurred at above-canopy wind speeds greater than 5 m s-1. We could show the importance of the enhancement of the <span class="hlt">gas</span> transport rate in relation with the wind intensity and corresponding <span class="hlt">air</span> pressure fluctuations characteristics. We directly detected and quantified the pressure-pumping effect on <span class="hlt">gas</span> transport in soil in a field study for the first time, and could thus validate and underpin the importance of this non</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15796111','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15796111"><span>Effects of ceiling-mounted HEPA-UV <span class="hlt">air</span> filters on airborne bacteria <span class="hlt">concentrations</span> in an indoor therapy pool building.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kujundzic, Elmira; Zander, David A; Hernandez, Mark; Angenent, Largus T; Henderson, David E; Miller, Shelly L</p> <p>2005-02-01</p> <p>The purpose of this study was to assess the effectiveness of a new generation of high-volume, ceiling-mounted high-efficiency particulate <span class="hlt">air</span> (HEPA)-ultraviolet (UV) <span class="hlt">air</span> filters (HUVAFs) for their ability to remove or inactivate bacterial aerosol. In an environmentally controlled full-scale laboratory chamber (87 m3), and an indoor therapy pool building, the mitigation ability of <span class="hlt">air</span> filters was assessed by comparing <span class="hlt">concentrations</span> of total bacteria, culturable bacteria, and airborne endotoxin with and without the <span class="hlt">air</span> filters operating under otherwise similar conditions. Controlled chamber tests with pure cultures of aerosolized Mycobacterium parafortuitum cells showed that the HUVAF unit tested provided an equivalent <span class="hlt">air</span>-exchange rate of 11 hr(-1). Using this equivalent <span class="hlt">air</span>-exchange rate as a design basis, three HUVAFs were installed in an indoor therapy pool building for bioaerosol mitigation, and their effectiveness was studied over a 2-year period. The HUVAFs reduced <span class="hlt">concentrations</span> of culturable bacteria by 69 and 80% during monitoring periods executed in respective years. The HUVAFs reduced <span class="hlt">concentrations</span> of total bacteria by 12 and 76% during the same monitoring period, respectively. Airborne endotoxin <span class="hlt">concentrations</span> were not affected by the HUVAF operation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890005190','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890005190"><span>Trace <span class="hlt">gas</span> measurements from whole <span class="hlt">air</span> samples collected over the Antarctic continent</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Heidt, L. E.; Vedder, J. F.; Pollock, Walter H.; Henry, Bruce E.; Lueb, Richard A.</p> <p>1988-01-01</p> <p>Whole <span class="hlt">air</span> samples collected aboard the NASA DC-8 and ER-2 aircraft as part of the Airborne Antarctic Ozone Experiment (AAOE) were analyzed in a field laboratory set up at Punta Arenas, Chile, in August and September, 1987. Mixing ratios obtained from <span class="hlt">gas</span> chromatographic analyses of these samples are presented for N2O, CFCl3, CFCl2, C2F3Cl3, CH3CCl3, CH4, and CO. Variations in the mixing ratios of these gases along the individual flight paths of the aircraft are used as tracers to indicate the history of <span class="hlt">air</span> masses over and near the Antarctic continent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.epa.gov/aboutepa/petition-epa-action-protect-communities-oil-and-gas-wells-toxic-air-pollution','PESTICIDES'); return false;" href="https://www.epa.gov/aboutepa/petition-epa-action-protect-communities-oil-and-gas-wells-toxic-air-pollution"><span>Petition for EPA action to protect communities from oil and <span class="hlt">gas</span> wells toxic <span class="hlt">air</span> pollution</span></a></p> <p><a target="_blank" href="http://www.epa.gov/pesticides/search.htm">EPA Pesticide Factsheets</a></p> <p></p> <p></p> <p>Petition submitted by Earthjustice urging EPA to list oil and <span class="hlt">gas</span> wells and associated equipment as an area sourcecategory and set national <span class="hlt">air</span> toxics standards to protect public health from these sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5191180','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5191180"><span>Development and Validation of a UAV Based System for <span class="hlt">Air</span> Pollution Measurements</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Villa, Tommaso Francesco; Salimi, Farhad; Morton, Kye; Morawska, Lidia; Gonzalez, Felipe</p> <p>2016-01-01</p> <p><span class="hlt">Air</span> quality data collection near pollution sources is difficult, particularly when sites are complex, have physical barriers, or are themselves moving. Small Unmanned Aerial Vehicles (UAVs) offer new approaches to <span class="hlt">air</span> pollution and atmospheric studies. However, there are a number of critical design decisions which need to be made to enable representative data collection, in particular the location of the <span class="hlt">air</span> sampler or <span class="hlt">air</span> sensor intake. The aim of this research was to establish the best mounting point for four <span class="hlt">gas</span> sensors and a Particle Number <span class="hlt">Concentration</span> (PNC) monitor, onboard a hexacopter, so to develop a UAV system capable of measuring point source emissions. The research included two different tests: (1) evaluate the <span class="hlt">air</span> flow behavior of a hexacopter, its downwash and upwash effect, by measuring <span class="hlt">air</span> speed along three axes to determine the location where the sensors should be mounted; (2) evaluate the use of <span class="hlt">gas</span> sensors for CO2, CO, NO2 and NO, and the PNC monitor (DISCmini) to assess the efficiency and performance of the UAV based system by measuring emissions from a diesel engine. The <span class="hlt">air</span> speed behavior map produced by test 1 shows the best mounting point for the sensors to be alongside the UAV. This position is less affected by the propeller downwash effect. Test 2 results demonstrated that the UAV propellers cause a dispersion effect shown by the decrease of <span class="hlt">gas</span> and PN <span class="hlt">concentration</span> measured in real time. A Linear Regression model was used to estimate how the sensor position, relative to the UAV center, affects pollutant <span class="hlt">concentration</span> measurements when the propellers are turned on. This research establishes guidelines on how to develop a UAV system to measure point source emissions. Such research should be undertaken before any UAV system is developed for real world data collection. PMID:28009820</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28009820','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28009820"><span>Development and Validation of a UAV Based System for <span class="hlt">Air</span> Pollution Measurements.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Villa, Tommaso Francesco; Salimi, Farhad; Morton, Kye; Morawska, Lidia; Gonzalez, Felipe</p> <p>2016-12-21</p> <p><span class="hlt">Air</span> quality data collection near pollution sources is difficult, particularly when sites are complex, have physical barriers, or are themselves moving. Small Unmanned Aerial Vehicles (UAVs) offer new approaches to <span class="hlt">air</span> pollution and atmospheric studies. However, there are a number of critical design decisions which need to be made to enable representative data collection, in particular the location of the <span class="hlt">air</span> sampler or <span class="hlt">air</span> sensor intake. The aim of this research was to establish the best mounting point for four <span class="hlt">gas</span> sensors and a Particle Number <span class="hlt">Concentration</span> (PNC) monitor, onboard a hexacopter, so to develop a UAV system capable of measuring point source emissions. The research included two different tests: (1) evaluate the <span class="hlt">air</span> flow behavior of a hexacopter, its downwash and upwash effect, by measuring <span class="hlt">air</span> speed along three axes to determine the location where the sensors should be mounted; (2) evaluate the use of <span class="hlt">gas</span> sensors for CO₂, CO, NO₂ and NO, and the PNC monitor (DISCmini) to assess the efficiency and performance of the UAV based system by measuring emissions from a diesel engine. The <span class="hlt">air</span> speed behavior map produced by test 1 shows the best mounting point for the sensors to be alongside the UAV. This position is less affected by the propeller downwash effect. Test 2 results demonstrated that the UAV propellers cause a dispersion effect shown by the decrease of <span class="hlt">gas</span> and PN <span class="hlt">concentration</span> measured in real time. A Linear Regression model was used to estimate how the sensor position, relative to the UAV center, affects pollutant <span class="hlt">concentration</span> measurements when the propellers are turned on. This research establishes guidelines on how to develop a UAV system to measure point source emissions. Such research should be undertaken before any UAV system is developed for real world data collection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4168419','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4168419"><span>Augmented Switching Linear Dynamical System Model for <span class="hlt">Gas</span> <span class="hlt">Concentration</span> Estimation with MOX Sensors in an Open Sampling System</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Di Lello, Enrico; Trincavelli, Marco; Bruyninckx, Herman; De Laet, Tinne</p> <p>2014-01-01</p> <p>In this paper, we introduce a Bayesian time series model approach for <span class="hlt">gas</span> <span class="hlt">concentration</span> estimation using Metal Oxide (MOX) sensors in Open Sampling System (OSS). Our approach focuses on the compensation of the slow response of MOX sensors, while concurrently solving the problem of estimating the <span class="hlt">gas</span> <span class="hlt">concentration</span> in OSS. The proposed Augmented Switching Linear System model allows to include all the sources of uncertainty arising at each step of the problem in a single coherent probabilistic formulation. In particular, the problem of detecting on-line the current sensor dynamical regime and estimating the underlying <span class="hlt">gas</span> <span class="hlt">concentration</span> under environmental disturbances and noisy measurements is formulated and solved as a statistical inference problem. Our model improves, with respect to the state of the art, where system modeling approaches have been already introduced, but only provided an indirect relative measures proportional to the <span class="hlt">gas</span> <span class="hlt">concentration</span> and the problem of modeling uncertainty was ignored. Our approach is validated experimentally and the performances in terms of speed of and quality of the <span class="hlt">gas</span> <span class="hlt">concentration</span> estimation are compared with the ones obtained using a photo-ionization detector. PMID:25019637</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=307570&keyword=energy+AND+storage&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=307570&keyword=energy+AND+storage&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span><span class="hlt">Air</span> Pollutant Emissions from Oil and <span class="hlt">Gas</span> Production pads (Investigating Low Cost Passive Samplers)</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>To help achieve the goal of sustainable, environmentally responsible development of oil and <span class="hlt">gas</span> resources, it isnecessary to understand the potential for <span class="hlt">air</span> pollutant emissions from various extraction and production (E&P)processes at the upstream, wellpad level. Upstream oil and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/6446224','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6446224"><span>The ejector flowmeter as <span class="hlt">air</span>/oxygen mixing device. An apparatus providing <span class="hlt">gas</span> mixtures with adjustable oxygen content for high-flow humidification systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Christensen, K N; Waaben, J; Jørgensen, S</p> <p>1980-04-01</p> <p>The ejector flowmeter is constructed for continuous removal of excess <span class="hlt">gas</span> from anaesthetic circuits. This instrument can be used as an <span class="hlt">air</span>/oxygen mixing device for high-flow humidification systems in wards where compressed <span class="hlt">air</span> is not available. Pure oxygen is used as driving <span class="hlt">gas</span> through the ejector. A nomogram has been constructed to show the relationship between oxygen driving pressure, inlet of <span class="hlt">air</span> to the flowmeter, FIO2 and total outflow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16271812','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16271812"><span>Atmospheric <span class="hlt">concentrations</span> and <span class="hlt">air</span>-sea exchanges of nonylphenol, tertiary octylphenol and nonylphenol monoethoxylate in the North Sea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xie, Zhiyong; Lakaschus, Soenke; Ebinghaus, Ralf; Caba, Armando; Ruck, Wolfgang</p> <p>2006-07-01</p> <p><span class="hlt">Concentrations</span> of nonylphenol isomers (NP), tertiary octylphenol (t-OP) and nonylphenol monoethoxylate isomers (NP1EO) have been simultaneously determined in the sea water and atmosphere of the North Sea. A decreasing <span class="hlt">concentration</span> profile appeared following the distance increasing from the coast to the central part of the North Sea. <span class="hlt">Air</span>-sea exchanges of t-OP and NP were estimated using the two-film resistance model based upon relative <span class="hlt">air</span>-water <span class="hlt">concentrations</span> and experimentally derived Henry's law constant. The average of <span class="hlt">air</span>-sea exchange fluxes was -12+/-6 ng m(-2)day(-1) for t-OP and -39+/-19 ng m(-2)day(-1) for NP, which indicates a net deposition is occurring. These results suggest that the <span class="hlt">air</span>-sea vapour exchange is an important process that intervenes in the mass balance of alkylphenols in the North Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26964236','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26964236"><span>[<span class="hlt">Gas</span> <span class="hlt">Concentration</span> Measurement Based on the Integral Value of Absorptance Spectrum].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Hui-jun; Tao, Shao-hua; Yang, Bing-chu; Deng, Hong-gui</p> <p>2015-12-01</p> <p>The absorptance spectrum of a <span class="hlt">gas</span> is the basis for the qualitative and quantitative analysis of the <span class="hlt">gas</span> by the law of the Lambert-Beer. The integral value of the absorptance spectrum is an important parameter to describe the characteristics of the <span class="hlt">gas</span> absorption. Based on the measured absorptance spectrum of a <span class="hlt">gas</span>, we collected the required data from the database of HIT-RAN, and chose one of the spectral lines and calculated the integral value of the absorptance spectrum in the frequency domain, and then substituted the integral value into Lambert-Beer's law to obtain the <span class="hlt">concentration</span> of the detected <span class="hlt">gas</span>. By calculating the integral value of the absorptance spectrum we can avoid the more complicated calculation of the spectral line function and a series of standard gases for calibration, so the <span class="hlt">gas</span> <span class="hlt">concentration</span> measurement will be simpler and faster. We studied the changing trends of the integral values of the absorptance spectrums versus temperature. Since temperature variation would cause the corresponding variation in pressure, we studied the changing trends of the integral values of the absorptance spectrums versus both the pressure not changed with temperature and changed with the temperature variation. Based on the two cases, we found that the integral values of the absorptance spectrums both would firstly increase, then decrease, and finally stabilize with temperature increasing, but the ranges of specific changing trend were different in the two cases. In the experiments, we found that the relative errors of the integrated values of the absorptance spectrum were much higher than 1% and still increased with temperature when we only considered the change of temperature and completely ignored the pressure affected by the temperature variation, and the relative errors of the integrated values of the absorptance spectrum were almost constant at about only 1% when we considered that the pressure were affected by the temperature variation. As the integral value</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040088390&hterms=laser+gas+spectroscopy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dlaser%2Bgas%2Bspectroscopy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088390&hterms=laser+gas+spectroscopy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dlaser%2Bgas%2Bspectroscopy"><span>Applications of Kalman filtering to real-time trace <span class="hlt">gas</span> <span class="hlt">concentration</span> measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Leleux, D. P.; Claps, R.; Chen, W.; Tittel, F. K.; Harman, T. L.</p> <p>2002-01-01</p> <p>A Kalman filtering technique is applied to the simultaneous detection of NH3 and CO2 with a diode-laser-based sensor operating at 1.53 micrometers. This technique is developed for improving the sensitivity and precision of trace <span class="hlt">gas</span> <span class="hlt">concentration</span> levels based on direct overtone laser absorption spectroscopy in the presence of various sensor noise sources. Filter performance is demonstrated to be adaptive to real-time noise and data statistics. Additionally, filter operation is successfully performed with dynamic ranges differing by three orders of magnitude. Details of Kalman filter theory applied to the acquired spectroscopic data are discussed. The effectiveness of this technique is evaluated by performing NH3 and CO2 <span class="hlt">concentration</span> measurements and utilizing it to monitor varying ammonia and carbon dioxide levels in a bioreactor for water reprocessing, located at the NASA-Johnson Space Center. Results indicate a sensitivity enhancement of six times, in terms of improved minimum detectable absorption by the <span class="hlt">gas</span> sensor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AtmEn..79..317A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AtmEn..79..317A"><span>Local emission of primary <span class="hlt">air</span> pollutants and its contribution to wet deposition and <span class="hlt">concentrations</span> of aerosols and gases in ambient <span class="hlt">air</span> in Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aikawa, Masahide; Hiraki, Takatoshi; Tomoyose, Nobutaka; Ohizumi, Tsuyoshi; Noguchi, Izumi; Murano, Kentaro; Mukai, Hitoshi</p> <p>2013-11-01</p> <p>We studied wet deposition by precipitation and the <span class="hlt">concentrations</span> of aerosols and gases in ambient <span class="hlt">air</span> in relation to the primary <span class="hlt">air</span> pollutants discharged from domestic areas. The <span class="hlt">concentrations</span> of aerosols and gases were influenced by nearby emissions except for non-sea-salt SO, which is transported long distances. The area facing the Sea of Japan showed much larger wet deposition than other areas, although the domestic emissions of the primary <span class="hlt">air</span> pollutants there were small and showed a peak in wet deposition from October to March, as distinct from April to September in other areas. We performed the correlation analyses between wet deposition of each component and the product of the <span class="hlt">concentrations</span> of corresponding aerosols and gases in ambient <span class="hlt">air</span> and the two-thirds power of the precipitation. From the results, following scavenging processes were suggested. • Sulfate and ammonium were scavenged in precipitation as particulate matter such as (NH4)2SO4 and NH4HSO4. • Nitrate was scavenged mainly in precipitation through gaseous HNO3. • Ammonium was complementarily scavenged in precipitation through aerosols such as (NH4)2SO4 and NH4HSO4 and through gaseous NH3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22739680','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22739680"><span><span class="hlt">Air</span> <span class="hlt">concentrations</span> of PBDEs on in-flight airplanes and assessment of flight crew inhalation exposure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Allen, Joseph G; Sumner, Ann Louise; Nishioka, Marcia G; Vallarino, Jose; Turner, Douglas J; Saltman, Hannah K; Spengler, John D</p> <p>2013-07-01</p> <p>To address the knowledge gaps regarding inhalation exposure of flight crew to polybrominated diphenyl ethers (PBDEs) on airplanes, we measured PBDE <span class="hlt">concentrations</span> in <span class="hlt">air</span> samples collected in the cabin <span class="hlt">air</span> at cruising altitudes and used Bayesian Decision Analysis (BDA) to evaluate the likelihood of inhalation exposure to result in the average daily dose (ADD) of a member of the flight crew to exceed EPA Reference Doses (RfDs), accounting for all other aircraft and non-aircraft exposures. A total of 59 <span class="hlt">air</span> samples were collected from different aircraft and analyzed for four PBDE congeners-BDE 47, 99, 100 and 209 (a subset were also analyzed for BDE 183). For congeners with a published RfD, high estimates of ADD were calculated for all non-aircraft exposure pathways and non-inhalation exposure onboard aircraft; inhalation exposure limits were then derived based on the difference between the RfD and ADDs for all other exposure pathways. The 95th percentile measured <span class="hlt">concentrations</span> of PBDEs in aircraft <span class="hlt">air</span> were <1% of the derived inhalation exposure limits. Likelihood probabilities of 95th percentile exposure <span class="hlt">concentrations</span> >1% of the defined exposure limit were zero for all congeners with published RfDs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29477113','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29477113"><span>Traditional and novel halogenated flame retardants in urban ambient <span class="hlt">air</span>: <span class="hlt">Gas</span>-particle partitioning, size distribution and health implications.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de la Torre, A; Barbas, B; Sanz, P; Navarro, I; Artíñano, B; Martínez, M A</p> <p>2018-07-15</p> <p>Urban ambient <span class="hlt">air</span> samples, including <span class="hlt">gas</span>-phase (PUF), total suspended particulates (TSP), PM 10 , PM 2.5 and PM 1 airborne particle fractions were collected to evaluate <span class="hlt">gas</span>-particle partitioning and size particle distribution of traditional and novel halogenated flame retardants. Simultaneously, passive <span class="hlt">air</span> samplers (PAS) were deployed in the same location. Analytes included 33 polybrominated diphenyl ether (PBDE), 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), hexabromobenzene (HBB), pentabromoethylbenzene (PBEB), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), dechloranes (Dec 602, 603, 604, 605 or Dechorane plus (DP)) and chlordane plus (CP). Clausius-Clapeyron equation, <span class="hlt">gas</span>-particle partition coefficient (K p ), fraction partitioned onto particles (φ) and human respiratory risk assessment were used to evaluate local or long-distance transport sources, <span class="hlt">gas</span>-particle partitioning sorption mechanisms, and implications for health, respectively. PBDEs were the FR with the highest levels (13.9pgm -3 , median TSP+PUF), followed by DP (1.56pgm -3 ), mirex (0.78pgm -3 ), PBEB (0.05pgm -3 ), and BB-153 (0.04pgm -3 ). PBDE congener pattern in particulate matter was dominated by BDE-209, while the contribution of more volatile congeners, BDE-28, -47, -99, and -100 was higher in <span class="hlt">gas</span>-phase. Congener contribution increases with particle size and bromination degree, being BDE-47 mostly bounded to particles≤PM 1 , BDE-99 to > PM 1 and BDE-209 to > PM 2.5 . No significant differences were found for PBDE and DP <span class="hlt">concentrations</span> obtained with passive and active samplers, demonstrating the ability of the formers to collect particulate material. Deposition efficiencies and fluxes on inhaled PBDEs and DP in human respiratory tract were calculated. Contribution in respiratory track was dominated by head airway (2.16 and 0.26pgh -1 , for PBDE and DP), followed by tracheobronchial (0.12 and 0.02pgh -1 ) and alveoli (0.01-0.002pgh -1 ) regions. Finally, hazard</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730012964','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730012964"><span>Effect of inlet-<span class="hlt">air</span> humidity on the formation of oxides of nitrogen in a <span class="hlt">gas</span>-turbine combustor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marchionna, N. R.</p> <p>1973-01-01</p> <p>Tests were conducted to determine the effect of inlet-<span class="hlt">air</span> humidity on the formation of oxides of nitrogen from a <span class="hlt">gas</span>-turbine combustor. Combustor inlet-<span class="hlt">air</span> temperature ranged from 450 F to 1050 F. The tests were run at a constant pressure of 6 atmospheres and reference Mach number of 0.065. The NO sub x emission index was found to decrease with increasing inlet-<span class="hlt">air</span> humidity at a constant exponential rate of 19 percent per mass percent water vapor in the <span class="hlt">air</span>. This decrease of NO sub x emission index with increasing humidity was found to be independent of inlet-<span class="hlt">air</span> temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AMT....11.3197E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AMT....11.3197E"><span>Preparation and analysis of zero gases for the measurement of trace VOCs in <span class="hlt">air</span> monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Englert, Jennifer; Claude, Anja; Demichelis, Alessia; Persijn, Stefan; Baldan, Annarita; Li, Jianrong; Plass-Duelmer, Christian; Michl, Katja; Tensing, Erasmus; Wortman, Rina; Ghorafi, Yousra; Lecuna, Maricarmen; Sassi, Guido; Sassi, Maria Paola; Kubistin, Dagmar</p> <p>2018-06-01</p> <p><span class="hlt">Air</span> quality observations are performed globally to monitor the status of the atmosphere and its level of pollution and to assess mitigation strategies. Regulations of <span class="hlt">air</span> quality monitoring programmes in various countries demand high-precision measurements for harmful substances often at low trace <span class="hlt">concentrations</span>. These requirements can only be achieved by using high-quality calibration gases including high-purity zero <span class="hlt">gas</span>. For volatile organic compound (VOC) observations, zero <span class="hlt">gas</span> is defined as being hydrocarbon-free and can be, for example, purified <span class="hlt">air</span>, nitrogen or helium. It is essential for the characterisation of the measurement devices and procedures, for instrument operation as well as for calibrations. Two commercial and one self-built <span class="hlt">gas</span> purifiers were tested for their VOC removal efficiency following a standardised procedure. The tested <span class="hlt">gas</span> purifiers included one adsorption cartridge with an inorganic media and two types of metal catalysts. A large range of VOCs were investigated, including the most abundant species typically measured at <span class="hlt">air</span> monitoring stations. Both catalysts were able to remove a large range of VOCs whilst the tested adsorption cartridge was not suitable to remove light compounds up to C4. Memory effects occurred for the adsorption cartridge when exposed to higher <span class="hlt">concentration</span>. This study emphasises the importance of explicitly examining a <span class="hlt">gas</span> purifier for its intended application before applying it in the field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22590946-determination-indoor-radon-concentrations-elementary-schools-fatih-district-istanbul','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22590946-determination-indoor-radon-concentrations-elementary-schools-fatih-district-istanbul"><span>Determination of indoor radon <span class="hlt">concentrations</span> at the elementary schools of Fatih district in Istanbul</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kurt, A., E-mail: aziz.kurt@istanbul.edu.tr; Yalcin, L. Sahin, E-mail: latife.sahin@gmail.com; Oktem, Y., E-mail: sgyks@istanbul.edu.tr</p> <p></p> <p>Radon is an odorless, tasteless, colorless noble radioactive <span class="hlt">gas</span> which is produced within the radioactive decay chain of Uranium. The Radon forms in rocks, diffuses into soil and then escapes into atmosphere. When human exposure to high <span class="hlt">concentration</span> of radon <span class="hlt">gas</span> from inside, risk of developing lung cancer is increased. There are many methods to determine {sup 222}Rn <span class="hlt">concentration</span> in the <span class="hlt">air</span>. In this study, radon <span class="hlt">concentration</span> of confined <span class="hlt">air</span> spaces were measured by using LR-115 solid state nuclear track detectors. 509 LR-115 nuclear trace detectors were placed to 25 schools in Fatih District and they effective dose values weremore » calculated. The results of measurements showed that the radon <span class="hlt">concentration</span> varies between 40-395 Bq/m{sup 3}. This results compared with Turkey’s limits (400 Bq/m{sup 3}) are low, conversely higher compared with WHO’s limits (100 Bq/m{sup 3}).« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770026435','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770026435"><span>Evaluation of analytical methodology for hydrocarbons in high pressure <span class="hlt">air</span> and nitrogen systems. [evaluation of methodology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1977-01-01</p> <p>Samples of liquid oxygen, high pressure nitrogen, low pressure nitrogen, and missile grade <span class="hlt">air</span> were studied to determine the hydrocarbon <span class="hlt">concentrations</span>. <span class="hlt">Concentration</span> of the samples was achieved by adsorption on a molecular sieve and activated charcoal. The trapped hydrocarbons were then desorbed and transferred to an analytical column in a <span class="hlt">gas</span> chromatograph. The sensitivity of the method depends on the volume of <span class="hlt">gas</span> passed through the adsorbent tubes. The value of the method was verified through recoverability and reproducibility studies. The use of this method enables LOX, GN2, and missile grade <span class="hlt">air</span> systems to be routinely monitored to determine low level increases in specific hydrocarbon <span class="hlt">concentration</span> that could lead to potentially hazardous conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25460425','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25460425"><span>Monitoring and modeling wetland chloride <span class="hlt">concentrations</span> in relationship to oil and <span class="hlt">gas</span> development.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Post van der Burg, Max; Tangen, Brian A</p> <p>2015-03-01</p> <p>Extraction of oil and <span class="hlt">gas</span> via unconventional methods is becoming an important aspect of energy production worldwide. Studying the effects of this development in countries where these technologies are being widely used may provide other countries, where development may be proposed, with some insight in terms of concerns associated with development. A fairly recent expansion of unconventional oil and <span class="hlt">gas</span> development in North America provides such an opportunity. Rapid increases in energy development in North America have caught the attention of managers and scientists as a potential stressor for wildlife and their habitats. Of particular concern in the Northern Great Plains of the U.S. is the potential for chloride-rich produced water associated with unconventional oil and <span class="hlt">gas</span> development to alter the water chemistry of wetlands. We describe a landscape scale modeling approach designed to examine the relationship between potential chloride contamination in wetlands and patterns of oil and <span class="hlt">gas</span> development. We used a spatial Bayesian hierarchical modeling approach to assess multiple models explaining chloride <span class="hlt">concentrations</span> in wetlands. These models included effects related to oil and <span class="hlt">gas</span> wells (e.g. age of wells, number of wells) and surficial geology (e.g. glacial till, outwash). We found that the model containing the number of wells and the surficial geology surrounding a wetland best explained variation in chloride <span class="hlt">concentrations</span>. Our spatial predictions showed regions of localized high chloride <span class="hlt">concentrations</span>. Given the spatiotemporal variability of regional wetland water chemistry, we do not regard our results as predictions of contamination, but rather as a way to identify locations that may require more intensive sampling or further investigation. We suggest that an approach like the one outlined here could easily be extended to more of an adaptive monitoring approach to answer questions about chloride contamination risk that are of interest to managers</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70154798','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70154798"><span>Monitoring and modeling wetland chloride <span class="hlt">concentrations</span> in relationship to oil and <span class="hlt">gas</span> development</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Post van der Burg, Max; Tangen, Brian A.</p> <p>2015-01-01</p> <p>Extraction of oil and <span class="hlt">gas</span> via unconventional methods is becoming an important aspect of energy production worldwide. Studying the effects of this development in countries where these technologies are being widely used may provide other countries, where development may be proposed, with some insight in terms of concerns associated with development. A fairly recent expansion of unconventional oil and <span class="hlt">gas</span> development in North America provides such an opportunity. Rapid increases in energy development in North America have caught the attention of managers and scientists as a potential stressor for wildlife and their habitats. Of particular concern in the Northern Great Plains of the U.S. is the potential for chloride-rich produced water associated with unconventional oil and <span class="hlt">gas</span> development to alter the water chemistry of wetlands. We describe a landscape scale modeling approach designed to examine the relationship between potential chloride contamination in wetlands and patterns of oil and <span class="hlt">gas</span> development. We used a spatial Bayesian hierarchical modeling approach to assess multiple models explaining chloride <span class="hlt">concentrations</span> in wetlands. These models included effects related to oil and <span class="hlt">gas</span> wells (e.g. age of wells, number of wells) and surficial geology (e.g. glacial till, outwash). We found that the model containing the number of wells and the surficial geology surrounding a wetland best explained variation in chloride <span class="hlt">concentrations</span>. Our spatial predictions showed regions of localized high chloride <span class="hlt">concentrations</span>. Given the spatiotemporal variability of regional wetland water chemistry, we do not regard our results as predictions of contamination, but rather as a way to identify locations that may require more intensive sampling or further investigation. We suggest that an approach like the one outlined here could easily be extended to more of an adaptive monitoring approach to answer questions about chloride contamination risk that are of interest to managers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840008521','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840008521"><span>Bending fatigue of electron-beam-welded foils. Application to a hydrodynamic <span class="hlt">air</span> bearing in the Chrysler/DOE upgraded automotive <span class="hlt">gas</span> tubine engine</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Saltsman, J. F.; Halford, G. R.</p> <p>1984-01-01</p> <p>A hydrodynamic <span class="hlt">air</span> bearing with a compliment surface is used in the <span class="hlt">gas</span> generator of an upgraded automotive <span class="hlt">gas</span> turbine engine. In the prototype design, the compliant surface is a thin foil spot welded at one end to the bearing cartridge. During operation, the foil failed along the line of spot welds which acted as a series of stress <span class="hlt">concentrators</span>. Because of its higher degree of geometric uniformity, electron beam welding of the foil was selected as an alternative to spot welding. Room temperature bending fatigue tests were conducted to determine the fatigue resistance of the electron beam welded foils. Equations were determined relating cycles to crack initiation and cycles to failure to nominal total strain range. A scaling procedure is presented for estimating the reduction in cyclic life when the foil is at its normal operating temperature of 260 C (500 F).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SPIE10621E..1BB','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SPIE10621E..1BB"><span>A new method research of monitoring low <span class="hlt">concentration</span> NO and SO2 mixed <span class="hlt">gas</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bo, Peng; Gao, Chao; Guo, Yongcai; Chen, Fang</p> <p>2018-01-01</p> <p>In order to reduce the pollution of the environment, China has implemented a new ultra-low emission control regulations for polluting <span class="hlt">gas</span>, requiring new coal-fired power plant emissions SO2 less than 30ppm, NO less than 75ppm, NO2 less than 50ppm, Monitoring low <span class="hlt">concentration</span> of NO and SO2 mixed gases , DOAS technology facing new challenges, SO2 absorb significantly weaken at the original absorption peak, what more the SNR is very low, it is difficult to extract the characteristic signal, and thus cannot obtain its <span class="hlt">concentration</span>. So it cannot separate the signal of NO from the mixed <span class="hlt">gas</span> at the wavelength of 200 230nm through the law of spectral superposition, it cannot calculate the <span class="hlt">concentration</span> of NO. The classical DOAS technology cannot meet the needs of monitoring. In this paper, we found another absorption spectrum segment of SO2, the SNR is 10 times higher than before, Will not be affected by NO, can calculate the <span class="hlt">concentration</span> of SO2 accurately, A new method of segmentation and demagnetization separation technology of spectral signals is proposed, which achieves the monitoring the low <span class="hlt">concentration</span> mixed <span class="hlt">gas</span> accurately. This function cannot be achieved by the classical DOAS. Detection limit of this method is 0.1ppm per meter which is higher than before, The relative error below 5% when the <span class="hlt">concentration</span> between 0 5ppm, the <span class="hlt">concentration</span> of NO between 6 75ppm and SO2 between 6 30ppm the relative error below 1.5%, it has made a great breakthrough In the low <span class="hlt">concentration</span> of NO and SO2 monitoring. It has great scientific significance and reference value for the development of coal-fired power plant emission control, atmospheric environmental monitoring and high-precision on-line instrumentation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ACP....14.4065G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ACP....14.4065G"><span>PAH <span class="hlt">concentrations</span> simulated with the AURAMS-PAH chemical transport model over Canada and the USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galarneau, E.; Makar, P. A.; Zheng, Q.; Narayan, J.; Zhang, J.; Moran, M. D.; Bari, M. A.; Pathela, S.; Chen, A.; Chlumsky, R.</p> <p>2014-04-01</p> <p>The offline Eulerian AURAMS (A Unified Regional <span class="hlt">Air</span> quality Modelling System) chemical transport model was adapted to simulate airborne <span class="hlt">concentrations</span> of seven PAHs (polycyclic aromatic hydrocarbons): phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene + triphenylene, and benzo[a]pyrene. The model was then run for the year 2002 with hourly output on a grid covering southern Canada and the continental USA with 42 km horizontal grid spacing. Model predictions were compared to ~5000 24 h-average PAH measurements from 45 sites, most of which were located in urban or industrial areas. Eight of the measurement sites also provided data on particle/<span class="hlt">gas</span> partitioning which had been modelled using two alternative schemes. This is the first known regional modelling study for PAHs over a North American domain and the first modelling study at any scale to compare alternative particle/<span class="hlt">gas</span> partitioning schemes against paired field measurements. The goal of the study was to provide output <span class="hlt">concentration</span> maps of use to assessing human inhalation exposure to PAHs in ambient <span class="hlt">air</span>. Annual average modelled total (<span class="hlt">gas</span> + particle) <span class="hlt">concentrations</span> were statistically indistinguishable from measured values for fluoranthene, pyrene and benz[a]anthracene whereas the model underestimated <span class="hlt">concentrations</span> of phenanthrene, anthracene and chrysene + triphenylene. Significance for benzo[a]pyrene performance was close to the statistical threshold and depended on the particle/<span class="hlt">gas</span> partitioning scheme employed. On a day-to-day basis, the model simulated total PAH <span class="hlt">concentrations</span> to the correct order of magnitude the majority of the time. The model showed seasonal differences in prediction quality for volatile species which suggests that a missing emission source such as <span class="hlt">air</span>-surface exchange should be included in future versions. Model performance differed substantially between measurement locations and the limited available evidence suggests that the model's spatial resolution was too</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/792964','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/792964"><span>Effect of outside <span class="hlt">air</span> ventilation rate on VOC <span class="hlt">concentrations</span> and emissions in a call center</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hodgson, A.T.; Faulkner, D.; Sullivan, D.P.</p> <p>2002-01-01</p> <p>A study of the relationship between outside <span class="hlt">air</span> ventilation rate and <span class="hlt">concentrations</span> of VOCs generated indoors was conducted in a call center. Ventilation rates were manipulated in the building's four <span class="hlt">air</span> handling units (AHUs). <span class="hlt">Concentrations</span> of VOCs in the AHU returns were measured on 7 days during a 13-week period. Indoor minus outdoor <span class="hlt">concentrations</span> and emission factors were calculated. The emission factor data was subjected to principal component analysis to identify groups of co-varying compounds based on source type. One vector represented emissions of solvents from cleaning products. Another vector identified occupant sources. Direct relationships between ventilation rate and concentrationsmore » were not observed for most of the abundant VOCs. This result emphasizes the importance of source control measures for limiting VOC <span class="hlt">concentrations</span> in buildings.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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