Science.gov

Sample records for air masses due

  1. Bias in Dobson total ozone measurements at high latitudes due to approximations in calculations of ozone absorption coefficients and air mass

    NASA Astrophysics Data System (ADS)

    Bernhard, G.; Evans, R. D.; Labow, G. J.; Oltmans, S. J.

    2005-05-01

    The Dobson spectrophotometer is the primary standard instrument for ground-based measurements of total column ozone. The accuracy of its data depends on the knowledge of ozone absorption coefficients used for data reduction. We document an error in the calculations that led to the set of absorption coefficients currently recommended by the World Meteorological Organisation (WMO). This error has little effect because an empirical adjustment was applied to the original calculations before the coefficients were adopted by WMO. We provide evidence that this adjustment was physically sound. The coefficients recommended by WMO are applied in the Dobson network without correction for the temperature dependence of the ozone absorption cross sections. On the basis of data measured by Dobson numbers 80 and 82, which were operated by the National Oceanic and Atmospheric Administration (NOAA) Climate Monitoring and Diagnostics Laboratory at the South Pole, we find that omission of temperature corrections may lead to systematic errors in Dobson ozone data of up to 4%. The standard Dobson ozone retrieval method further assumes that the ozone layer is located at a fixed height. This approximation leads to errors in air mass calculations, which are particularly relevant at high latitudes where ozone measurements are performed at large solar zenith angles (SZA). At the South Pole, systematic errors caused by this approximation may exceed 2% for SZAs larger than 80°. The bias is largest when the vertical ozone distribution is distorted by the "ozone hole" and may lead to underestimation of total ozone by 4% at SZA = 85° (air mass 9). Dobson measurements at the South Pole were compared with ozone data from a collocated SUV-100 UV spectroradiometer and Version 8 overpass data from NASA's Total Ozone Mapping Spectrometer (TOMS). Uncorrected Dobson ozone values tend to be lower than data from the two other instruments when total ozone is below 170 Dobson units or SZAs are larger than

  2. Voice Change Due to Paratracheal Air Cysts

    PubMed Central

    Rhee, Youn Ju; Han, Sung Joon; Chong, Yoo Young; Cho, Hyun Jin; Kang, Shin Kwang; Lee, Choong-Sik; Kang, Min-Woong

    2016-01-01

    Paratracheal air cysts are a rare entity in which cystic formation occurs adjacent to the trachea. Most patients with paratracheal air cysts are asymptomatic, and the cysts are detected incidentally on chest radiograph or computed tomography (CT) scan. Most symptomatic patients complain of pulmonary symptoms or repeated respiratory infection. Rarely, the air cysts can lead to paralysis of the recurrent laryngeal nerve as a result of direct compression. We report a case of a 59-year-old male patient who presented with voice change, and the cause was identified as paratracheal air cysts on a chest CT scan. Surgical resection via video-assisted mediastinoscopy was performed, and the voice recovered immediately after the operation. PMID:27525245

  3. Air Pressure Controlled Mass Measurement System

    NASA Astrophysics Data System (ADS)

    Zhong, Ruilin; Wang, Jian; Cai, Changqing; Yao, Hong; Ding, Jin'an; Zhang, Yue; Wang, Xiaolei

    Mass measurement is influenced by air pressure, temperature, humidity and other facts. In order to reduce the influence, mass laboratory of National Institute of Metrology, China has developed an air pressure controlled mass measurement system. In this system, an automatic mass comparator is installed in an airtight chamber. The Chamber is equipped with a pressure controller and associate valves, thus the air pressure can be changed and stabilized to the pre-set value, the preferred pressure range is from 200 hPa to 1100 hPa. In order to keep the environment inside the chamber stable, the display and control part of the mass comparator are moved outside the chamber, and connected to the mass comparator by feed-throughs. Also a lifting device is designed for this system which can easily lift up the upper part of the chamber, thus weights can be easily put inside the mass comparator. The whole system is put on a marble platform, and the temperature and humidity of the laboratory is very stable. The temperature, humidity, and carbon dioxide content inside the chamber are measured in real time and can be used to get air density. Mass measurement cycle from 1100 hPa to 200 hPa and back to 1100 hPa shows the effective of the system.

  4. Human health risks in megacities due to air pollution

    NASA Astrophysics Data System (ADS)

    Gurjar, B. R.; Jain, A.; Sharma, A.; Agarwal, A.; Gupta, P.; Nagpure, A. S.; Lelieveld, J.

    2010-11-01

    This study evaluates the health risks in megacities in terms of mortality and morbidity due to air pollution. A new spreadsheet model, Risk of Mortality/Morbidity due to Air Pollution (Ri-MAP), is used to estimate the excess numbers of deaths and illnesses. By adopting the World Health Organization (WHO) guideline concentrations for the air pollutants SO 2, NO 2 and total suspended particles (TSP), concentration-response relationships and a population attributable-risk proportion concept are employed. Results suggest that some megacities like Los Angeles, New York, Osaka Kobe, Sao Paulo and Tokyo have very low excess cases in total mortality from these pollutants. In contrast, the approximate numbers of cases is highest in Karachi (15,000/yr) characterized by a very high concentration of total TSP (˜670 μg m -3). Dhaka (7000/yr), Beijing (5500/yr), Karachi (5200/yr), Cairo (5000/yr) and Delhi (3500/yr) rank highest with cardiovascular mortality. The morbidity (hospital admissions) due to Chronic Obstructive Pulmonary Disease (COPD) follows the tendency of cardiovascular mortality. Dhaka and Karachi lead the rankings, having about 2100/yr excess cases, while Osaka-Kobe (˜20/yr) and Sao Paulo (˜50/yr) are at the low end of all megacities considered. Since air pollution is increasing in many megacities, and our database of measured pollutants is limited to the period up to 2000 and does not include all relevant components (e.g. O 3), these numbers should be interpreted as lower limits. South Asian megacities most urgently need improvement of air quality to prevent excess mortality and morbidity due to exceptionally high levels of air pollution. The risk estimates obtained from Ri-MAP present a realistic baseline evaluation for the consequences of ambient air pollution in comparison to simple air quality indices, and can be expanded and improved in parallel with the development of air pollution monitoring networks.

  5. Supersonic Air Flow due to Solid-Liquid Impact

    NASA Astrophysics Data System (ADS)

    Gekle, Stephan; Peters, Ivo R.; Gordillo, José Manuel; van der Meer, Devaraj; Lohse, Detlef

    2010-01-01

    A solid object impacting on liquid creates a liquid jet due to the collapse of the impact cavity. Using visualization experiments with smoke particles and multiscale simulations, we show that in addition, a high-speed air jet is pushed out of the cavity. Despite an impact velocity of only 1m/s, this air jet attains supersonic speeds already when the cavity is slightly larger than 1 mm in diameter. The structure of the air flow closely resembles that of compressible flow through a nozzle—with the key difference that here the “nozzle” is a liquid cavity shrinking rapidly in time.

  6. Warm-air advection, air mass transformation and fog causes rapid ice melt

    NASA Astrophysics Data System (ADS)

    Tjernström, Michael; Shupe, Matthew D.; Brooks, Ian M.; Persson, P. Ola G.; Prytherch, John; Salisbury, Dominic J.; Sedlar, Joseph; Achtert, Peggy; Brooks, Barbara J.; Johnston, Paul E.; Sotiropoulou, Georgia; Wolfe, Dan

    2015-07-01

    Direct observations during intense warm-air advection over the East Siberian Sea reveal a period of rapid sea-ice melt. A semistationary, high-pressure system north of the Bering Strait forced northward advection of warm, moist air from the continent. Air-mass transformation over melting sea ice formed a strong, surface-based temperature inversion in which dense fog formed. This induced a positive net longwave radiation at the surface while reducing net solar radiation only marginally; the inversion also resulted in downward turbulent heat flux. The sum of these processes enhanced the surface energy flux by an average of ~15 W m-2 for a week. Satellite images before and after the episode show sea-ice concentrations decreasing from > 90% to ~50% over a large area affected by the air-mass transformation. We argue that this rapid melt was triggered by the increased heat flux from the atmosphere due to the warm-air advection.

  7. The Effective Mass of a Ball in the Air

    ERIC Educational Resources Information Center

    Messer, J.; Pantaleone, J.

    2010-01-01

    The air surrounding a projectile affects the projectile's motion in three very different ways: the drag force, the buoyant force, and the added mass. The added mass is an increase in the projectile's inertia from the motion of the air around it. Here we experimentally measure the added mass of a spherical projectile in air. The results agree well…

  8. Air pollution effects due to deregulation of the electric industry

    NASA Astrophysics Data System (ADS)

    Davoodi, Khojasteh Riaz

    ) nuclear sources until the year 2005. Each module was analyzed separately and the result from each module was transferred into the Air Quality Impact model. The model assesses the changes in electricity generation within each module due to deregulation and these changes can then be correlated to the emission of air pollutants in the United States.

  9. Effect of load carriage on gait due to firefighting air bottle configuration.

    PubMed

    Park, Kiwon; Hur, Pilwon; Rosengren, Karl S; Horn, Gavin P; Hsiao-Wecksler, Elizabeth T

    2010-07-01

    The air bottle configuration (mass and size) used with a firefighter's self-contained breathing apparatus may affect functional gait performance and slip/trip/fall risk, contributing to one of the most common and costly fire ground injuries to this population. To examine the potential effect of bottle mass and size on firefighter gait performance, four 30-min air bottle configurations were tested. To quantify biomechanical gait performance, kinetic and kinematic gait data were collected on 24 male firefighters while walking at normal and fast speeds during three conditions (no obstacle, 10 cm or 30 cm stationary obstacle). Bottle mass, obstacle height and walking speed - but not bottle size - were found to significantly impact gait parameters. Ten subjects (42%) contacted the taller obstacle while wearing heavier bottles, suggesting greater risk for tripping. Heavier bottles also resulted in larger forces by the trailing leg in both the anterior-posterior and vertical directions, suggesting greater risk for slipping. These results suggest that increased bottle weight may result in a decrease in gait performance and an increase in fall risk. STATEMENT OF RELEVANCE: Occupations, such as firefighting, often require use of a self-contained breathing apparatus that includes a pressurised air bottle. No systematic assessment has investigated how modest changes in load carriage due to bottle configuration (mass and size) might affect gait behaviour, especially when crossing obstacles. Bottle mass, but not size, was found to decrease gait performance and increase fall risk. PMID:20582769

  10. Solar wind mass-loading due to dust

    NASA Astrophysics Data System (ADS)

    Rasca, A. P.; Horányi, M.

    2013-06-01

    Collisionless mass-loading by interplanetary dust particles is expected to cause a significant disruption in the flow of the solar wind. Dust particles near the Sun can become a source of ions and neutrals due to evaporation and sputtering. This mass-loading effect can lead to the formation of collisionless shocks, as it was first discussed in the case of solar wind interaction with comets. This effect can also be compared with a de Laval nozzle, which behaves differently between subsonic and supersonic flows. We investigate the effects of mass-loading resulting from sun-grazing comets or collisions by larger bodies in the vicinity of the Sun, where the solar wind transitions from subsonic to supersonic speeds. We look at results obtained using a simple 1D hydrodynamic model to mass-load ionized dust into the the wind near the sonic point, which are relevant for understanding the acceleration of the solar wind and possible changes in its composition due to dust.

  11. Solar Wind Mass-Loading Due to Dust

    NASA Astrophysics Data System (ADS)

    Rasca, A.; Horanyi, M.

    2011-12-01

    Collisionless mass-loading by interplanetary dust particles is expected to cause a significant disruption in the flow of the solar wind. Dust particles near the Sun can become a source of ions and neutrals due to evaporation and sputtering. This mass-loading effect can lead to the formation of collisionless shocks, as it was first discussed in the case of solar wind interaction with comets. This effect can also be compared with a de Laval nozzle, which behaves differently between subsonic and supersonic flows. We investigate the effects of mass-loading resulting from sun-grazing comets or collisions in the vicinity of the Sun, where the solar wind transitions from subsonic to supersonic speeds. We implement a hydrodynamic numerical model to generate a steady wind extending out to the inner heliosphere. Dust is introduced through a set of mass-loading source terms, and the model is evolved using a shock-capturing scheme. These results are relevant for understanding the acceleration of the solar wind and possible changes in its composition due to dust.

  12. Mass Distribution and Mass Transport in the Earth System: Recent Scientific Progress Due to Interdisciplinary Research

    NASA Astrophysics Data System (ADS)

    Kusche, Jürgen; Klemann, Volker; Sneeuw, Nico

    2014-11-01

    This Special Issue on "Mass Distribution and Mass Transport in the Earth System: Recent Scientific Progress due to Interdisciplinary Research" reports a number of findings resulting from a collaborative effort run from 2006 until 2013, in the framework of the DFG Priority Program 1257 "Mass Distribution and Mass Transport in the Earth System". Contributions have been arranged along five lines, i.e. (1) improvements in geodesy: satellite mass monitoring through gravimetry and altimetry, (2) applications in large-scale hydrology, (3) applications in solid Earth research, (4) applications in cryospheric research, (5) applications in ocean sciences.

  13. Modelling heat and mass transfer in a membrane-based air-to-air enthalpy exchanger

    NASA Astrophysics Data System (ADS)

    Dugaria, S.; Moro, L.; Del, D., Col

    2015-11-01

    The diffusion of total energy recovery systems could lead to a significant reduction in the energy demand for building air-conditioning. With these devices, sensible heat and humidity can be recovered in winter from the exhaust airstream, while, in summer, the incoming air stream can be cooled and dehumidified by transferring the excess heat and moisture to the exhaust air stream. Membrane based enthalpy exchangers are composed by different channels separated by semi-permeable membranes. The membrane allows moisture transfer under vapour pressure difference, or water concentration difference, between the two sides and, at the same time, it is ideally impermeable to air and other contaminants present in exhaust air. Heat transfer between the airstreams occurs through the membrane due to the temperature gradient. The aim of this work is to develop a detailed model of the coupled heat and mass transfer mechanisms through the membrane between the two airstreams. After a review of the most relevant models published in the scientific literature, the governing equations are presented and some simplifying assumptions are analysed and discussed. As a result, a steady-state, two-dimensional finite difference numerical model is setup. The developed model is able to predict temperature and humidity evolution inside the channels. Sensible and latent heat transfer rate, as well as moisture transfer rate, are determined. A sensitive analysis is conducted in order to determine the more influential parameters on the thermal and vapour transfer.

  14. Indoor air quality. [Health hazards due to energy conservation measures

    SciTech Connect

    Hollowell, C.D.

    1981-06-01

    Rising energy prices, among other factors, have generated an incentive to reduce ventilation rates and thereby reduce the cost of heating and cooling buildings. Reduced ventilation in buildings may significantly increase exposure to indoor air pollution and perhaps have adverse effects on occupant health and comfort. Preliminary findings suggest that reduced ventilation may adversely affect indoor air quality unless appropriate control strategies are undertaken. The strategies used to control indoor air pollution depend on the specific pollutant or class of pollutants encountered, and differ somewhat depending on whether the application is to an existing building or a new building under design and construction. Whenever possible, the first course of action is prevention or reduction of pollutant emissions at the source. In most buildings, control measures involve a combination of prevention, removal, and suppression. Common sources of indoor air pollution in buildings, the specific pollutants emitted by each source, the potential health effects, and possible control techniques are discussed.

  15. Crop loss due to air pollution in The Netherlands.

    PubMed

    van der Eerden, L J; Tonneijck, A E; Wijnands, J H

    1988-01-01

    The extent of yield reduction and economic loss caused by air pollution has been estimated for The Netherlands. Based on available data on direct effects only, each species was designated as sensitive, moderately sensitive or tolerant. On a nationwide scale, only ozone (O3), sulphur dioxide (SO2), and hydrogen fluoride (HF) exceeded effect thresholds. Effects from pollutant combinations were assumed to be additive. Yield reductions were calculated, using 10 exposure-response relationships and concentration data from the Dutch air pollution monitoring network. Changes in air pollution levels result in changes in supply. By multiplying the supply with the current price, the so-called crop volume was calculated. Subsequently, changes in crop volume were converted into economic terms, taking into account demand elasticity. On the basis of these calculations, air pollution in The Netherlands reduces total crop volume by 5%:3.4% by O3, 1.2% by SO2, and 0.4% by HF. The slope of the nonlinear relationship between crop volume reduction and exposure level increases at higher concentrations. In general, air pollution causes relatively little loss to producers, since yield reductions are largely compensated by higher prices. If air pollution in The Netherlands would be reduced to background concentrations, consumers would experience a net gain of Dfl 640 million (US 320 million dollars). Although large amounts of data were attained through literature and our own experience for this study, many assumptions still had to be made to arrive at these conclusions. With the current available knowledge, validation of our results in the field is not yet possible. PMID:15092562

  16. Infant death due to air embolism from peripheral venous infusion.

    PubMed

    Sowell, Matthew W; Lovelady, Cari L; Brogdon, B G; Wecht, Cyril H

    2007-01-01

    An otherwise healthy male infant was brought to the hospital because the mother suspected superficial infection at the operative site 5 days after an inguinal hernia repair. He was admitted to the pediatric unit overnight to be evaluated by his surgeon the next morning. When a venous infusion of maintenance fluids was started, the patient immediately went into cardio-respiratory arrest and was pronounced dead after resuscitation efforts failed. Subsequently, air collections were found in both venous and arterial circulations, including the splenoportal system. Detailed review of the clinical presentation and course, laboratory results, radiological, and pathological findings, along with a review of pertinent literature provides an explanation for the death by air embolism. Apparent inconsistent findings both radiographically and at autopsy are resolved. The mechanism of distribution of air to both systemic and splenoportal circulation is discussed. We believe this to be only the eighth case reported in English-language literature of infantile death from peripheral venous infusion. In all age groups, we find only six other cases in the English-language literature of gas found concomitantly in both the systemic and portal venous systems. PMID:17209934

  17. Charge and discharge of polar cold air mass in northern hemispheric winter

    NASA Astrophysics Data System (ADS)

    Kanno, Yuki; Abdillah, Muhammad Rais; Iwasaki, Toshiki

    2015-09-01

    This study shows the variability of polar cold air mass amount below potential temperature of 280 K, and north of 45°N can be understood with a concept of charge and discharge, where anomalously large daily discharge indicates an intermittent occurrence of cold air outbreak. The polar cold air mass amount north of 45°N gradually charges up due to diabatic cooling but dramatically discharges due to cold air outbreak with a pulse width of about 5 days. Cold air outbreaks tend to bring colder winter in East Asia and the east coast of North America, while warmer winter prevails on the northern side of these regions. The cold air mass amount south of 45°N increases just after a cold air outbreak but returns to the normal level soon because of its life time of about 3 days. Therefore, monthly mean of total cold air mass amount in the Northern Hemisphere is negatively correlated with the monthly mean discharge.

  18. Elemental composition of different air masses over Jeju Island, South Korea

    NASA Astrophysics Data System (ADS)

    Kang, Jeongwon; Choi, Man-Sik; Yi, Hi-Il; Jeong, Kap-Sik; Chae, Jung-Sun; Cheong, Chang-Sik

    2013-03-01

    We investigated the characteristics (concentrations and compositional changes) of atmospheric elements in total suspended particulates through source-receptor relationships using cluster analyses to classify air mass back-trajectories arriving at Gosan, Jeju Island, South Korea, from October 2003 to December 2008. Five trajectory clusters were chosen to explain the transport regimes. Continental outflows of natural and anthropogenic aerosols from Asian dust source regions and eastern China during the colder period could increase element concentrations at Gosan. Elemental levels at Gosan decreased in air masses that passed over marine regions (East China Sea, Pacific Ocean/southern side of Kyushu Island in Japan, and East Sea/southern side of South Korea) during the warmer rainy period due to lower source intensity and dilution by the marine air mass. Anthropogenic pollutants were often major components in air masses passing over marine regions. Air mass characterization by elemental concentration and composition revealed that enrichment by non-sea-salt sulfur in the air mass originated from eastern China, indicative of the main sulfur emitter in northeast Asia. The apportionment of V and Ni by principal component analysis as a marker of heavy oil combustion suggested different residence times and deposition rates from other anthropogenic components in the air. Regionally intermediate concentrations of pollutants were found in the atmosphere over the Korean peninsula.

  19. Air-mass origin in the tropical lower stratosphere: The influence of Asian boundary layer air

    NASA Astrophysics Data System (ADS)

    Orbe, Clara; Waugh, Darryn W.; Newman, Paul A.

    2015-05-01

    A climatology of air-mass origin in the tropical lower stratosphere is presented for the Goddard Earth Observing System Chemistry Climate Model. During late boreal summer and fall, air-mass fractions reveal that as much as 20% of the air in the tropical lower stratosphere last contacted the planetary boundary layer (PBL) over Asia; by comparison, the air-mass fractions corresponding to last PBL contact over North America and over Europe are negligible. Asian air reaches the extratropical tropopause within a few days of leaving the boundary layer and is quasi-horizontally transported into the tropical lower stratosphere, where it persists until January. The rapid injection of Asian air into the lower stratosphere—and its persistence in the deep tropics through late (boreal) winter—is important as industrial emissions over East Asia continue to increase. Hence, the Asian monsoon may play an increasingly important role in shaping stratospheric composition.

  20. Air pollution and health risks due to vehicle traffic.

    PubMed

    Zhang, Kai; Batterman, Stuart

    2013-04-15

    Traffic congestion increases vehicle emissions and degrades ambient air quality, and recent studies have shown excess morbidity and mortality for drivers, commuters and individuals living near major roadways. Presently, our understanding of the air pollution impacts from congestion on roads is very limited. This study demonstrates an approach to characterize risks of traffic for on- and near-road populations. Simulation modeling was used to estimate on- and near-road NO2 concentrations and health risks for freeway and arterial scenarios attributable to traffic for different traffic volumes during rush hour periods. The modeling used emission factors from two different models (Comprehensive Modal Emissions Model and Motor Vehicle Emissions Factor Model version 6.2), an empirical traffic speed-volume relationship, the California Line Source Dispersion Model, an empirical NO2-NOx relationship, estimated travel time changes during congestion, and concentration-response relationships from the literature, which give emergency doctor visits, hospital admissions and mortality attributed to NO2 exposure. An incremental analysis, which expresses the change in health risks for small increases in traffic volume, showed non-linear effects. For a freeway, "U" shaped trends of incremental risks were predicted for on-road populations, and incremental risks are flat at low traffic volumes for near-road populations. For an arterial road, incremental risks increased sharply for both on- and near-road populations as traffic increased. These patterns result from changes in emission factors, the NO2-NOx relationship, the travel delay for the on-road population, and the extended duration of rush hour for the near-road population. This study suggests that health risks from congestion are potentially significant, and that additional traffic can significantly increase risks, depending on the type of road and other factors. Further, evaluations of risk associated with congestion must

  1. Ions in oceanic and continental air masses

    SciTech Connect

    Tanner, D.J.; Eisele, F.L. )

    1991-01-20

    Measurements of tropospheric ions and several trace atmospheric neutral species have been performed at Cheeka Peak Research Station and at Mauna Loa Observatory. Two new positive ion species at masses 114 and 102 have been identified as protonated caprolactam and a saturated 6-carbon primary amine, respectively. In the negative ion spectrum, methane sulfonic acid (MSA) has been identified as the parent species responsible for an ion commonly observed at mass 95 during these two studies. The diurnal variations of gas phase H{sub 2}SO{sub 4} and MSA were also measured at Cheeka Peak and have typically been found to be present in the sub-ppt range. Ion assisted measurements at Mauna Loa Observatory of pyridine and ammonia indicate concentrations of 2.5 and 70 ppt, respectively, with at least a factor of 2 uncertainty. Interesting variations and potential sources of several of the observed ions are also discussed.

  2. Fundamental mass transfer models for indoor air pollution sources

    SciTech Connect

    Tichenor, B.A.; Guo, Z.; Sparks, L.E.

    1993-01-01

    The paper discusses a simple, fundamental mass transfer model, based on Fick's Law of Diffusion, for indoor air pollution wet sorbent-based sources. (Note: Models are needed to predict emissions from indoor sources. While empirical approaches based on dynamic chamber data are useful, a more fundamental approach is needed to fully elucidate the relevant mass transfer processes). In the model, the mass transfer rate is assumed to be gas-phase limited and controlled by the boundary layer mass transfer coefficient, the saturation vapor pressure of the material being emitted, and the mass of volatile material remaining. Results of static and dynamic chamber tests, as well as test house studies, are presented.

  3. Aerosol chemical components in Alaska air masses: 1. Aged pollution

    NASA Astrophysics Data System (ADS)

    Shaw, Glenn E.

    1991-12-01

    A 4-year Alaska chemical data set of aerosols or "dust" in the air clearly reveals a mixture of distinct aerosol components with different and interesting chemical composition, one or two being ascribed to pollution imported to Alaska by winds all the way from other continents. Of particular note is a strong chemical contrast between what we imagine to be highly scavenged, orographically lifted, northern Pacific air (Pacific marine air mass) and stagnant Arctic air (polar air mass), the latter containing seasonal average concentrations of between 2-4 times the concentration of the former, at least for pollution markers noncrustal vanadium, noncrustal manganese, arsenic, selenium, bromine, and antimony. The findings concur our old discovery that Arctic air is persistently polluted (Arctic haze), but Pacific air is relatively clean, in spite of the fact that Alaska is downwind of major pollution sources in the Orient. This is remarkable. In this the first of a two-part paper, we concentrate on the pollution component found primarily during incursion of Arctic polar air. Two major occurrences of visual haze with optical depths of approximately 0.2 and elevated aerosol concentration lasting about a month (spring 1985 and 1986) were affiliated with strong incoming transport of polar air, temperatures ranging from 10° to 20°C below normal (polar air) and air trajectory hindcasts leading back to industrial pollution sources in Eurasia. These long-range transport pollution events brought metal-rich aerosol of removal-resistant submicron particles. The size, chemistry, and meteorology all strongly suggest the presence of a well-aged (10-100 day) polluted air mass. An important implication is that in spring a large fraction of the Arctic polar air mass becomes charged with by-products of industrial pollution. In this multiyear chemical data set one finds a notable summer-winter contrast, changing by factors of 2 to 4 for pollution markers As, Se, Sb, and noncrustal

  4. An investigation on cracking of glasspanes due to air overpressure

    SciTech Connect

    Prakash, A.J.; Nabiullah, M.; Dhar, B.B.

    1994-12-31

    The study is an approach made in simulating air overpressures induced by surface blasting from those produced during gallery blasting in the laboratory, and experiments conducted on a portable window with a view to establish the sound pressure level (SPL) for cracking of window glasspanes. Eight different strengths of commercial explosives normally being used in blasting practices, were fired in the cannon of explosive gallery. SPL recorded on the seventh channel of a digital seismograph (SINCO-6) provided with FFT facility, are compared with those produced from surface blastings conducted in different Indian geomining conditions. They are found to be similar in frequency characteristics. A model of portable window provided with two replaceable glass panes has been designed and fabricated for the experiment in the explosive gallery. Stresses developed on the glass panes and the SPL in different stages were monitored to study the threshold level of damage. The first crack has been observed in the glass panes at the SPL of 162.3 dB ({minus}3.97 Kpa) and in the 5--20 Hz frequency band.

  5. Temporal Geophysical Signatures Due to Contaminant Mass Remediation

    EPA Science Inventory

    Geophysical surveys acquired over a ten year period are used to document changes in bulk electrical conductivity associated with the attenuation of hydrocarbon contaminants at the former fire training facility (FT-02) Wurtsmith Air Force base (WAFB), Oscoda, MI, USA. Initial inv...

  6. Moisture Risk in Unvented Attics Due to Air Leakage Paths

    SciTech Connect

    Prahl, D.; Shaffer, M.

    2014-11-01

    IBACOS completed an initial analysis of moisture damage potential in an unvented attic insulated with closed-cell spray polyurethane foam. To complete this analysis, the research team collected field data, used computational fluid dynamics to quantify the airflow rates through individual airflow (crack) paths, simulated hourly flow rates through the leakage paths with CONTAM software, correlated the CONTAM flow rates with indoor humidity ratios from Building Energy Optimization software, and used Warme und Feuchte instationar Pro two-dimensional modeling to determine the moisture content of the building materials surrounding the cracks. Given the number of simplifying assumptions and numerical models associated with this analysis, the results indicate that localized damage due to high moisture content of the roof sheathing is possible under very low airflow rates. Reducing the number of assumptions and approximations through field studies and laboratory experiments would be valuable to understand the real-world moisture damage potential in unvented attics.

  7. Moisture Risk in Unvented Attics Due to Air Leakage Paths

    SciTech Connect

    Prahl, D.; Shaffer, M.

    2014-11-01

    IBACOS completed an initial analysis of moisture damage potential in an unvented attic insulated with closed-cell spray polyurethane foam. To complete this analysis, the research team collected field data, used computational fluid dynamics to quantify the airflow rates through individual airflow (crack) paths, simulated hourly flow rates through the leakage paths with CONTAM software, correlated the CONTAM flow rates with indoor humidity ratios from Building Energy Optimization software, and used Wärme und Feuchte instationär Pro two-dimensional modeling to determine the moisture content of the building materials surrounding the cracks. Given the number of simplifying assumptions and numerical models associated with this analysis, the results indicate that localized damage due to high moisture content of the roof sheathing is possible under very low airflow rates. Reducing the number of assumptions and approximations through field studies and laboratory experiments would be valuable to understand the real-world moisture damage potential in unvented attics.

  8. IMPLICATIONS OF MASS AND ENERGY LOSS DUE TO CORONAL MASS EJECTIONS ON MAGNETICALLY ACTIVE STARS

    SciTech Connect

    Drake, Jeremy J.; Cohen, Ofer; Yashiro, Seiji; Gopalswamy, Nat

    2013-02-20

    Analysis of a database of solar coronal mass ejections (CMEs) and associated flares over the period 1996-2007 finds well-behaved power-law relationships between the 1-8 A flare X-ray fluence and CME mass and kinetic energy. We extrapolate these relationships to lower and higher flare energies to estimate the mass and energy loss due to CMEs from stellar coronae, assuming that the observed X-ray emission of the latter is dominated by flares with a frequency as a function of energy dn/dE = kE {sup -{alpha}}. For solar-like stars at saturated levels of X-ray activity, the implied losses depend fairly weakly on the assumed value of {alpha} and are very large: M-dot {approx}5 Multiplication-Sign 10{sup -10} M{sub sun} yr{sup -1} and E-dot {approx}0.1 L{sub sun}. In order to avoid such large energy requirements, either the relationships between CME mass and speed and flare energy must flatten for X-ray fluence {approx}> 10{sup 31} erg, or the flare-CME association must drop significantly below 1 for more energetic events. If active coronae are dominated by flares, then the total coronal energy budget is likely to be up to an order of magnitude larger than the canonical 10{sup -3} L {sub bol} X-ray saturation threshold. This raises the question of what is the maximum energy a magnetic dynamo can extract from a star? For an energy budget of 1% of L {sub bol}, the CME mass loss rate is about 5 Multiplication-Sign 10{sup -11} M {sub Sun} yr{sup -1}.

  9. Comment on "Improved ray tracing air mass numbers model"

    NASA Astrophysics Data System (ADS)

    van der Werf, Siebren Y.

    2008-01-01

    Air mass numbers have traditionally been obtained by techniques that use height as the integration variable. This introduces an inherent singularity at the horizon, and ad hoc solutions have been invented to cope with it. A survey of the possible options including integration by height, zenith angle, and horizontal distance or path length is presented. Ray tracing by path length is shown to avoid singularities both at the horizon and in the zenith. A fourth-order Runge-Kutta numerical integration scheme is presented, which treats refraction and air mass as path integrals. The latter may optionally be split out into separate contributions of the atmosphere's constituents.

  10. Dirty air, dirty power. Mortality and health damage due to air pollution from power plants

    SciTech Connect

    Schneider, Conrad G.; Padian, M.

    2004-06-15

    The Clean Air Task Force commissioned Abt Associates, the consulting firm relied upon by US EPA to assess the health benefits of many of the agency's air regulatory programs. The report documents the asthma attacks, hospitalisations, lost work and school days, and premature deaths linked to pollution from power plants. A first report was released in 2000. The 2004 report documents for the first time the number of heart attacks and lung cancer deaths that would be caused by power plants in 2010 and 2020. It compares the premature deaths that would result under the Bush administration's air pollution plan, the existing US Clean Air Act, and a proposal sponsored by Senator Jim Jeffords to strengthen the Clean Air Act. In general it was found that the administration's plan would produce the fewest benefits. The full study is available from the EPA, abstracted separately on the Coal Abstracts database. 65 refs., 2 apps.

  11. Damping of prominence longitudinal oscillations due to mass accretion

    NASA Astrophysics Data System (ADS)

    Ruderman, Michael S.; Luna, Manuel

    2016-06-01

    We study the damping of longitudinal oscillations of a prominence thread caused by the mass accretion. We suggested a simple model describing this phenomenon. In this model we considered a thin curved magnetic tube filled with the plasma. The prominence thread is in the central part of the tube and it consists of dense cold plasma. The parts of the tube at the two sides of the thread are filled with hot rarefied plasma. We assume that there are flows of rarefied plasma toward the thread caused by the plasma evaporation at the magnetic tube footpoints. Our main assumption is that the hot plasma is instantaneously accommodated by the thread when it arrives at the thread, and its temperature and density become equal to those of the thread. Then we derive the system of ordinary differential equations describing the thread dynamics. We solve this system of ordinary differential equations in two particular cases. In the first case we assume that the magnetic tube is composed of an arc of a circle with two straight lines attached to its ends such that the whole curve is smooth. A very important property of this model is that the equations describing the thread oscillations are linear for any oscillation amplitude. We obtain the analytical solution of the governing equations. Then we obtain the analytical expressions for the oscillation damping time and periods. We find that the damping time is inversely proportional to the accretion rate. The oscillation periods increase with time. We conclude that the oscillations can damp in a few periods if the inclination angle is sufficiently small, not larger that 10°, and the flow speed is sufficiently large, not less that 30 km s-1. In the second model we consider the tube with the shape of an arc of a circle. The thread oscillates with the pendulum frequency dependent exclusively on the radius of curvature of the arc. The damping depends on the mass accretion rate and the initial mass of the threads, that is the mass of the

  12. FUNDAMENTAL MASS TRANSFER MODELS FOR INDOOR AIR POLLUTION SOURCES

    EPA Science Inventory

    The paper discusses a simple, fundamental mass transfer model, based on Fick's Law of Diffusion, for indoor air pollution wet sorbent-based sources. (Note: Models are needed to predict emissions from indoor sources. hile empirical approaches based on dynamic chamber data are usef...

  13. Variability of local PM10 mass concentrations in connection with blocking air circulation

    NASA Astrophysics Data System (ADS)

    Ştefan, Sabina; Roman, Iuliana

    2015-06-01

    The aim of this paper is to analyze the temporal variability of Particulate Matter mass concentrations in connection with air circulation, for eight rural sites situated in the Central and Eastern parts of Europe. The stations from Poland, Hungary and Romania are rural stations without sources of pollutants. The analysis covers four winters, between December 2004 and February 2008. The pollution episodes were selected to explain air circulation influence. The results show that the causes of pollution were local, due to high mean sea level pressure and the blocking, as air circulation on large scale, was dominant in the cases of enhanced pollution in the selected area.

  14. Case of a Lung Mass due to Melioidosis in Mexico

    PubMed Central

    Truong, Kimberly K.; Moghaddam, Samer; Saghbini, Samer Al; Saatian, Bahman

    2015-01-01

    Patient: Female, 70 Final Diagnosis: Melioidosis Symptoms: Chills • fever • neck pain • night sweats Medication: — Clinical Procedure: Incision and drainage • endobronchial ultrasound guided biopsy Specialty: Infectious Diseases Objective: Rare disease Background: Melioidosis, an infection caused by the gram-negative bacterium Burkholderia pseudomallei, is an important cause of pneumonia, skin infection, sepsis, and death in Southeast Asia and Australia, but is exceedingly rare in North America. Pulmonary melioidosis typically presents as acute bacterial pneumonia or cavitary lung lesions resembling tuberculosis. Case Report: We report melioidosis in a 70-year-old active smoker from Mexico with no history of travel to disease-endemic areas. The patient presented with a left supraclavicular abscess and a non-cavitary, left lung mass encasing a pulmonary vein. Incision and drainage of the patient’s subcutaneous abscess isolated B. pseudomallei, and fine-needle aspiration of enlarged mediastinal lymph nodes revealed the presence of intracellular gram-negative bacilli with no evidence of malignancy. Biochemical tests determined that the strain the patient acquired from Mexico is identical to only 1 other isolate from Thailand. Conclusions: This report highlights the blurring epidemiological borders of this organism, its rare presentation mimicking lung malignancy, and an aggressive antimicrobial treatment that resulted in resolution of the patient’s symptoms. PMID:25943405

  15. 40 CFR 86.166-12 - Method for calculating emissions due to air conditioning leakage.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Method for calculating emissions due to air conditioning leakage. 86.166-12 Section 86.166-12 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for...

  16. 40 CFR 86.166-12 - Method for calculating emissions due to air conditioning leakage.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Method for calculating emissions due to air conditioning leakage. 86.166-12 Section 86.166-12 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for...

  17. Dusty air masses transport between Amazon Basin and Caribbean Islands

    NASA Astrophysics Data System (ADS)

    Euphrasie-Clotilde, Lovely; Molinie, Jack; Prospero, Joseph; Feuillard, Tony; Brute, Francenor; Jeannot, Alexis

    2015-04-01

    Depend on the month, African desert dust affect different parts of the North Atlantic Ocean. From December to April, Saharan dust outbreaks are often reported over the amazon basin and from May to November over the Caribbean islands and the southern regions of USA. This annual oscillation of Saharan dust presence, related to the ITCZ position, is perturbed some time, during March. Indeed, over Guadeloupe, the air quality network observed between 2007 and 2012 several dust events during March. In this paper, using HISPLIT back trajectories, we analyzed air masses trajectories for March dust events observed in Guadeloupe, from 2007 to 2012.We observed that the high pressure positions over the Atlantic Ocean allow the transport of dusty air masses from southern region of West Africa to the Caribbean Sea with a path crossing close to coastal region of French Guyana. Complementary investigations including the relationship between PM10 concentrations recorded in two sites Pointe-a-Pitre in the Caribbean, and Cayenne in French Guyana, have been done. Moreover we focus on the mean delay observed between the times arrival. All the results show a link between pathway of dusty air masses present over amazon basin and over the Caribbean region during several event of March. The next step will be the comparison of mineral dust composition for this particular month.

  18. Analytical model for contaminant mass removal by air sparging

    SciTech Connect

    Rabideau, A.J.; Blayden, J.M.

    1998-12-31

    An analytical model was developed to predict the removal of volatile organic compounds (VOCs) from ground water by air sparging (AS). The model treats the air sparging zone as a completely mixed reactor subject to the removal of dissolved contaminants by volatilization, advection, and first-order decay. Nonequilibrium desorption is approximated as a first-order mass transfer process. The model reproduces the tailing and rebound behavior often observed at AS sites, and would normally require the estimation of three site-specific parameters. Dimensional analysis demonstrates that predicting tailing can be interpreted in terms of kinetic desorption or diffusion of aqueous phase contaminants into discrete air channels. Related work is ongoing to test the model against field data.

  19. The mass and speed dependence of meteor air plasma temperatures

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Laux, Christophe O.; Wilson, Michael A.; Schaller, Emily L.

    2004-01-01

    The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

  20. Annoyance due to noise and air pollution to the residents of heavily frequented streets

    NASA Technical Reports Server (NTRS)

    Wanner, H. U.; Wehrli, B.; Nemecek, J.; Turrian, V.

    1980-01-01

    The residents of different streets with varying traffic density and building density were questioned about annoyance due to traffic noise and air pollution. Results show that annoyance felt is dependent not only on the measured noise levels and/or air pollution concentrations, but that there do exist interactions between the residential quarters and annoyance. These interactions should be considered when fixing the limits and standards.

  1. Enhanced formation of secondary air pollutants and aggravation of urban smog due to crop residue burning emissions in North India

    NASA Astrophysics Data System (ADS)

    Sarkar, Chinmoy; Kumar, Vinod; Sinha, Vinayak

    2013-04-01

    Biomass burning causes intense perturbations to regional atmospheric chemistry and air quality and is a significant global source of reactive pollutants to the atmosphere (Andreae and Merlet, 2001). In November 2012, large areas in North India including New Delhi experienced several weeks of aggravated smog and poor air quality due to the impact of crop residue burning, which is a biannual post harvest activity that occurs during Oct-Nov and April-May every year in the agricultural belts of North western India. In-situ high temporal resolution (1 measurement every minute) measurements of a suite of volatile organic compounds measured using proton transfer reaction mass spectrometry (PTR-MS) such as acetonitrile (biomass burning tracer) and aromatic hydrocarbons were performed simultaneously with carbon monoxide, nitrogen oxides, ozone and aerosol mass concentrations (PM 2.5 and PM 10) at a suburban site (30.667°N, 76.729°E and 310 m asl), impacted by air masses that had passed over the burning fields less than 72 hours ago. By using data from the same season but before the post harvest crop residue burning activity had commenced, we were able to quantify enhancements in ambient levels of the measured species due to the crop residue burning activity. When air masses influenced by the fire emissions reached the measurement site, peak values of about 8 ppbV acetonitrile, 4 ppmV CO, 100 ppbV NOx , 30 ppbV toluene and 15 ppbV benzene were observed which represented a factor of 2-5 increase over their ambient levels in the non-fire influenced period. Emission ratios of aromatic hydrocarbons/CO also showed a marked increase. Non fire event (N.F. E.) influenced and fire event (F.E.) influenced air masses had the following emission ratio enhancements: benzene/CO (N.F.E = 3; F.E. = 5), toluene/CO (N.F.E = 4; F.E. = 8.7) and sum of C8 aromatics/CO (N.F.E = 4; F.E. = 7.3) and sum of C9 aromatics/CO (N.F.E = 2.6; F.E. = 3.4). The OH reactivity of air masses which has strong

  2. Evaluation of biological air filters for livestock ventilation air by membrane inlet mass spectrometry.

    PubMed

    Feilberg, Anders; Adamsen, Anders P S; Lindholst, Sabine; Lyngbye, Merete; Schäfer, Annette

    2010-01-01

    Biological air filters have been proposed as a cost-effective technology for reducing odor emissions from intensive swine production facilities. In this work we present results from the application of membrane inlet mass spectrometry (MIMS) for continuously monitoring the removal of odorous compounds in biological air filters. The sensitivity and selectivity were tested on synthetic samples of selected odorous compounds, and linearity and detection limits in the lower ppb range were demonstrated for all compounds tested (methanethiol, dimethyl sulfide, carboxylic acids, 4-methylphenol, aldehydes, indole, and skatole) except trimethylamine. The method was applied in situ at two full-scale filters installed at swine houses. The results have been compared with analyses by thermal desorption gas chromatography-mass spectrometry (TD-GC/MS), and odor was measured by olfactometry. By comparison with TD-GC/MS, observed MIMS signals were assigned to 4-methylphenol, 4-ethylphenol, indole, skatole, the sum of volatile reduced organic sulfur compounds (ROS), and three subgroups of carboxylic acids. The removal rates were observed to be related to air-water partitioning with removal efficiencies in the range of 0 to 50% for low-soluble organic sulfur compounds and high removal efficiencies (typically 80-100%) for more soluble phenols and carboxylic acids. Based on the results and published odor threshold values, it is estimated that the low removal efficiency of ROS is the main limitation for achieving a higher odor reduction. PMID:20400604

  3. Air mass distribution and the heterogeneity of the climate change signal in the Hudson Bay/Foxe Basin region, Canada

    NASA Astrophysics Data System (ADS)

    Leung, Andrew; Gough, William

    2016-08-01

    The linkage between changes in air mass distribution and temperature trends from 1971 to 2010 is explored in the Hudson Bay/Foxe Basin region. Statistically significant temperature increases were found of varying spatial and temporal magnitude. Concurrent statistically significant changes in air mass frequency at the same locations were also detected, particularly in the declining frequency of dry polar (DP) air. These two sets of changes were found to be linked, and we thus conclude that the heterogeneity of the climatic warming signal in the region is at least partially the result of a fundamental shift in the concurrent air mass frequency in addition to global and regional changes in radiative forcing due to increases in long-lived greenhouse gases.

  4. High-Altitude Air Mass Zero Calibration of Solar Cells

    NASA Technical Reports Server (NTRS)

    Woodyard, James R.; Snyder, David B.

    2005-01-01

    Air mass zero calibration of solar cells has been carried out for several years by NASA Glenn Research Center using a Lear-25 aircraft and Langley plots. The calibration flights are carried out during early fall and late winter when the tropopause is at the lowest altitude. Measurements are made starting at about 50,000 feet and continue down to the tropopause. A joint NASA/Wayne State University program called Suntracker is underway to explore the use of weather balloon and communication technologies to characterize solar cells at elevations up to about 100 kft. The balloon flights are low-cost and can be carried out any time of the year. AMO solar cell characterization employing the mountaintop, aircraft and balloon methods are reviewed. Results of cell characterization with the Suntracker are reported and compared with the NASA Glenn Research Center aircraft method.

  5. Monitoring Trace Contaminants in Air Via Ion Trap Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Palmer, Peter T.; Karr, Dane; Pearson, Richard; Valero, Gustavo; Wong, Carla

    1995-01-01

    Recent passage of the Clean Air Act with its stricter regulation of toxic gas emissions, and the ever-growing number of applications which require faster turnaround times between sampling and analysis are two major factors which are helping to drive the development of new instrument technologies for in-situ, on-line, real-time monitoring. The ion trap, with its small size, excellent sensitivity, and tandem mass spectrometry capability is a rapidly evolving technology which is well-suited for these applications. In this paper, we describe the use of a commercial ion trap instrument for monitoring trace levels of chlorofluorocarbons (CFCs) and volatile organic compounds (VOCs) in air. A number of sample introduction devices including a direct transfer line interface, short column GC, and a cryotrapping interface are employed to achieve increasing levels of sensitivity. MS, MS/MS, and MS/MS/MS methods are compared to illustrate trade-offs between sensitivity and selectivity. Filtered Noise Field (FNF) technology is found to be an excellent means for achieving lower detection limits through selective storage of the ion(s) of interest during ionization. Figures of merit including typical sample sizes, detection limits, and response times are provided. The results indicate the potential of these techniques for atmospheric assessments, the High Speed Research Program, and advanced life support monitoring applications for NASA.

  6. Identification and Tracking of Polluted Air Masses in the South-Central Coast Air Basin.

    NASA Astrophysics Data System (ADS)

    Moore, G. E.; Douglas, S. G.; Kessler, R. C.; Killus, J. P.

    1991-05-01

    Canister samples of air taken during the South-Central Coast Cooperative Air Monitoring Program (SCCCAMP) 1985 field study program were analyzed for concentrations of over 50 hydrocarbons as well as chlorofluorocarbons (CFCs), carbon monoxide, hydrogen, and methane. Additional evidence of location and timing of airmass origin was obtained by utilizing long-lived halocarbons such as F-12 as `tracers of opportunity' in conjunction with known source profiles. Wind trajectories were developed from hourly gridded wind fields produced by a diagnostic wind model utilizing observed wind data. These wind trajectories were used to determine how pollutants from major source areas might be transported to sampling sites. Particulate lidar height-distance traverses were made from aircraft that provided a view of pollutant layering. Mixing height and vertical pollutant concentration distributions were obtained in order to determine if observed pollutant concentrations were consistent with the degree of stagnation present and hypothesized transport pathway.Analyses to track specific polluted air masses were conducted for the 13 September, 21 September, 23-24 September, and 2-3 October 1985 intensive study periods. The analyses find that elevated ozone concentrations during these periods are primarily attributed to transport and storage of ozone-enriched air from Los Angeles. During one type of episode (2-3 October) ozone and ozone precursors are stored near the surface over the Santa Barbara Channel overnight and transported into coastal areas on the following day. In another type of episode (23-24 September) ozone is transported into the study domain from the San Fernando Valley and Los Angeles via flow around the Santa Monica Hills. Transport of pollutant-enriched air takes place in a layer 200-500 m aloft, in many places overlaying cleaner marine-layer air. This advected ozone is mixed down to contribute to ground-level ozone concentrations over terrain where the marine layer

  7. Ultrafine particles pollution in urban coastal air due to ship emissions

    NASA Astrophysics Data System (ADS)

    González, Yenny; Rodríguez, Sergio; Guerra García, Juan Carlos; Trujillo, Juan Luis; García, Rosa

    2011-09-01

    Two years of experimental data (2008-2009) of particle number (≥2.5 nm diameter) and black carbon concentrations and of gaseous pollutants recorded in the ambient air of a coastal city were analysed in order to assess the impact of ship emissions on the ultrafine particles (UFPs, diameter <100 nm) concentrations in urban ambient air. The observed relationship between particle number and the other air pollutants, allowed segregating the contribution of vehicle exhaust and of ship emissions to the UFP concentrations in the urban ambient air. Vehicle exhausts resulted in high concentrations of UFP, black carbon and NO x during the early morning, when UFPs showed concentrations 15-30 × 10 3 cm -3. Pollutants linked to this source rapidly decreased when inland sea breeze started to flow. However, this airflow resulted in inland transport of ship plumes (emitted in the harbour and in the sea) into the city and in high concentrations of SO 2, NO x and UFP from mid morning to the evening. In this context, UFPs showed concentrations 35-50 × 10 3 cm -3, being the 65-70% of these linked to ship emissions mostly related to SO 2 (gas phase precursor). UFPs pollution is a matter of concern due to adverse effects on human health. Up to the date, most of studies on urban air quality and UFPs have focused on vehicle exhaust emissions. This study shows how inland transport of ship plumes due to sea breeze blowing results in UFPs pollution in coastal cities.

  8. Influence of Baseline Air Masses and Wildland Fires on Air Quality in the Western United States

    NASA Astrophysics Data System (ADS)

    Wigder, Nicole L.

    This dissertation focuses on several key uncertainties related to particulate matter (PM) and O3 concentrations in the western U.S. Each analysis conducted for this dissertation centers on data collected at the Mount Bachelor Observatory (MBO, 2.8 km a.s.l., 43.98° N, 121.69° W), a mountaintop research site in central Oregon, U.S. The first component of this dissertation is an analysis of the contribution of baseline O3 to observed O3 concentrations in two western U.S. urban areas, Enumclaw, Washington (WA) and Boise, Idaho, during 2004 -- 2010. I compared O3 data from two baseline sites (MBO and Cheeka Peak, WA) to O3 concentrations in the two urban areas on days when backward air mass trajectories showed transport between the baseline and urban sites. I found that the urban areas studied had relatively low O3 on the days with a strong influence from baseline air masses (28.3 -- 48.3 ppbv). These data suggested that there was low production of O3 from urban emissions on these days, which allowed me to quantify the impact of baseline O3 on urban O3 concentrations. A regression of the Boise and MBO O3 observations showed that free tropospheric air masses were diluted by 50% as they were entrained into the boundary layer at Boise. These air masses can contain high O3 concentrations (>70 ppbv) from Asian pollution sources or stratospheric intrusions, indicating that these sources can greatly contribute to urban surface O 3 concentrations. In addition, I found that the elevation and surface temperature of the urban areas studied impacted baseline O3 concentrations in these areas, with higher elevation and greater surface temperatures leading to greater O3 concentrations. The second and third components of this dissertation are analyses of the impact of wildland fires on PM and O3 concentrations in the western U.S. For both of these analyses, I calculated pollutant enhancement ratios for PM, O3, and other species in wildland fire plumes observed at MBO during 2004

  9. Mass transfer of VOCs in laboratory-scale air sparging tank.

    PubMed

    Chao, Keh-Ping; Ong, Say Kee; Huang, Mei-Chuan

    2008-04-15

    Volatilization of VOCs was investigated using a 55-gal laboratory-scale model in which air sparging experiments were conducted with a vertical air injection well. In addition, X-ray imaging of an air sparging sand box showed air flows were in the form of air bubbles or channels depending on the size of the porous media. Air-water mass transfer was quantified using the air-water mass transfer coefficient which was determined by fitting the experimental data to a two-zone model. The two-zone model is a one-dimensional lumped model that accounts for the effects of air flow type and diffusion of VOCs in the aqueous phase. The experimental air-water mass transfer coefficients, KGa, obtained from this study ranged from 10(-2) to 10(-3)1/min. From a correlation analysis, the air-water mass transfer coefficient was found to be directly proportional to the air flow rate and the mean particle size of soil but inversely proportional to Henry's constant. The correlation results implied that the air-water mass transfer coefficient was strongly affected by the size of porous media and the air flow rates. PMID:17804158

  10. RADIOLOGICAL RELEASES DUE TO AIR AND SILICA DUST ACTIVATION IN EMPLACEMENT DRIFTS

    SciTech Connect

    J.S. Tang

    2003-05-07

    The purpose of this calculation is to determine the quantity and significance of annual Monitored Geologic Repository (MGR) subsurface normal radiological releases due to neutron activation of air and silica dust in emplacement drifts. This calculation includes the following items: (1) Calculate activation of ventilation airflow through emplacement drifts to quantify radioactive gaseous releases; and (2) Calculate the bounding potential activated silica dust concentration and releases. The sources of silica dust may arise from air supply to emplacement drifts as well as host rock around emplacement drifts. For this calculation, the source of dust is conservatively assumed to be the host rock (Assumption 3.6), which is subject to long-term neutron exposure resulting in saturated radioactivity. The scope of this calculation is limited to releases from activated air and silica dust only, excluding natural radioactive releases such as radon or releases from defective waste packages (breached or contaminated). This work supports the repository ventilation system design and Preclosure Safety Analysis. This includes MGR items classified as Quality Level 1, for example, the Uncanistered Spent Nuclear Fuel Waste Package (CRWMS M&O [Civilian Radioactive Waste Management and Operation Contractor] 1999a, page 7). Therefore, this calculation is subject to the requirements of the ''Quality Assurance Requirements and Description'' (DOE [U.S. Department of Energy] 2003). The performance of the calculation and development of this document are carried out in accordance with AP-3.12Q, ''Design Calculation and Analyses'' and LP-3.30Q-BSC, ''Hazards Analysis System''.

  11. Impacts on ambient air quality due to flaring activities in one of Oman's oilfields.

    PubMed

    Abdul-Wahab, Sabah; Ali, Sappurd; Sardar, Sabir; Irfan, Naseem

    2012-01-01

    This work was conducted to assess the impacts on workplace and ambient air quality due to release of sulfur dioxide (SO(2)) into the atmosphere at Al-Noor production station, located in southern desert of Sultanate of Oman. The SO(2) is released because of oxidation of H(2)S to SO(2) on flaring of H(2)S rich off gas at the Al-Noor. In the first phase of the study, CALPUFF modeling system was used to predict the ground level concentrations of SO(2) emissions from the flare stacks. The evaluation of the modeling system was carried out by comparing the predicted results with that of the measured. In the second stage of the study, the estimated results were compared with the air quality standards/guidelines set by Omani regulatory authorities as well as by World Health Organization (WHO). It was concluded on the basis of current study that the sensitive individuals in the workplace of the Al-Noor could experience adverse health effects due to short-term exposure of SO(2). PMID:22315930

  12. A framework for assessing risk reduction due to DNAPL mass removal from low permeability soils

    SciTech Connect

    Freeze, R.A.; McWhorter, D.B.

    1996-08-01

    Many emerging remediation technologies are designed to remove contaminant mass from source zones at DNAPL sites in response to regulatory requirements. There is often concern in the regulated community as to whether mass removal actually reduces risk, or whether the small risk reductions achieved warrant the large costs incurred. This paper sets out a framework for quantifying the degree to which risk is reduced as mass is removed from shallow, saturated, low-permeability, dual-porosity, DNAPL source zones. Risk is defined in terms of meeting an alternate concentration level (ACL) at a compliance well in an aquifer underlying the source zone. The ACL is back-calculated from a carcinogenic health-risk characterization at a downstream water-supply well. Source-zone mass-removal efficiencies are heavily dependent on the distribution of mass between media (fractures, matrix) and phases (dissolved, sorbed, free product). Due to the uncertainties in currently-available technology performance data, the scope of the paper is limited to developing a framework for generic technologies rather than making risk-reduction calculations for specific technologies. Despite the qualitative nature of the exercise, results imply that very high mass-removal efficiencies are required to achieve significant long-term risk reduction with technology, applications of finite duration. 17 refs., 7 figs., 6 tabs.

  13. Mathematical modeling of heat exchange between mine air and rock mass during fire

    SciTech Connect

    A.E. Krasnoshtein; B.P. Kazakov; A.V. Shalimov

    2006-05-15

    Solution of problems on heat exchange between ventilating air and rock mass and on gas admixture propagation in mine workings serve as a base for considering changes in heat-gas-air state at a mine after inflammation. The presented mathematical relations allow calculation of a varied velocity and movement direction of air flows, their temperatures and smoking conditions during fire.

  14. Vertical air mass exchange driven by the local circulation on the northern slope of Mount Everest

    NASA Astrophysics Data System (ADS)

    Zhou, Libo; Zou, Han; Ma, Shupo; Li, Peng; Zhu, Jinhuan; Huo, Cuiping

    2011-01-01

    To better understand vertical air mass exchange driven by local circulation in the Himalayas, the volume flux of air mass is estimated in the Rongbuk Valley on the northern slope of Mount Everest, based on a volume closure method and wind-profiler measurements during the HEST2006 campaign in June 2006. Vertical air mass exchange was found to be dominated by a strong downward mass transfer from the late morning to late night. The average vertical air volume flux was 0.09 m s-1, which could be equivalent to a daily ventilation of 30 times the enclosed valley volume. This vertical air mass exchange process was greatly affected by the evolution of the South Asian summer monsoon (SASM), with a strong downward transfer during the SASM break stage, and a weak transfer during the SASM active stage.

  15. Occupational exposure to particulate air pollution and mortality due to ischaemic heart disease and cerebrovascular disease

    PubMed Central

    Torén, Kjell; Bergdahl, Ingvar A; Nilsson, Tohr; Järvholm, Bengt

    2007-01-01

    Objectives A growing number of epidemiological studies are showing that ambient exposure to particulate matter air pollution is a risk factor for cardiovascular disease; however, whether occupational exposure increases this risk is not clear. The aim of the present study was to examine whether occupational exposure to particulate air pollution increases the risk for ischaemic heart disease and cerebrovascular disease. Methods The study population was a cohort of 176 309 occupationally exposed Swedish male construction workers and 71 778 unexposed male construction workers. The definition of exposure to inorganic dust (asbestos, man‐made mineral fibres, dust from cement, concrete and quartz), wood dust, fumes (metal fumes, asphalt fumes and diesel exhaust) and gases and irritants (organic solvents and reactive chemicals) was based on a job‐exposure matrix with focus on exposure in the mid‐1970s. The cohort was followed from 1971 to 2002 with regard to mortality to ischaemic heart disease and cerebrovascular disease. Relative risks (RR) were obtained by the person‐years method and from Poisson regression models adjusting for baseline values of blood pressure, body mass index, age and smoking habits. Results Any occupational particulate air pollution was associated with an increased risk for ischemic heart disease (RR 1.13, 95% CI 1.07 to 1.19), but there was no increased risk for cerebrovascular disease (RR 0.97, 95% CI 0.88 to 1.07). There was an increased risk for ischaemic heart disease and exposure to inorganic dust (RR 1.07, 95% CI 1.03 to 1.12) and exposure to fumes (RR 1.05, 95% CI 1.00 to 1.10), especially diesel exhaust (RR 1.18, 95% CI 1.13 to 1.24). There was no significantly increased risk for cerebrovascular disease and exposure to inorganic dust, fumes or wood dust. Conclusions Occupational exposure to particulate air pollution, especially diesel exhaust, among construction workers increases the risk for ischaemic heart disease. PMID

  16. Risk assessment of the fatality due to explosion in land mass transport infrastructure by fast transient dynamic analysis.

    PubMed

    Giannopoulos, G; Larcher, M; Casadei, F; Solomos, G

    2010-01-15

    Terrorist attacks in New York have shocked the world community showing clearly the vulnerability of air transport in such events. However, the terrorist attacks in Madrid and London showed that land mass transport infrastructure is equally vulnerable in case of similar attacks. The fact that there has not been substantial investment in the domain of risk analysis and evaluation of the possible effects due to such events in land mass transportation infrastructure leaves large room for new developments that could eventually fill this gap. In the present work using the finite element code EUROPLEXUS there has been a large effort to perform a complete study of the land mass infrastructure in case of explosion events. This study includes a train station, a metro station and a metro carriage providing thus valuable simulation data for a variety of different situations. For the analysis of these structures it has been necessary to apply a laser scanning method for the acquisition of geometrical data, to improve the simulation capabilities of EUROPLEXUS by adding failure capabilities for specific finite elements, to implement new material models (e.g. glass), and to add new modules that achieve data post-processing for the calculation of fatal and non-fatal injuries risk. The aforementioned improvements are explained in the present work with emphasis in the newly developed risk analysis features of EUROPLEXUS. PMID:19773121

  17. A Comparison of the Red Green Blue Air Mass Imagery and Hyperspectral Infrared Retrieved Profiles

    NASA Technical Reports Server (NTRS)

    Berndt, E. B.; Folmer, Michael; Dunion, Jason

    2014-01-01

    The Red Green Blue (RGB) Air Mass imagery is derived from multiple channels or paired channel differences. Multiple channel products typically provide additional information than a single channel can provide alone. The RGB Air Mass imagery simplifies the interpretation of temperature and moisture characteristics of air masses surrounding synoptic and mesoscale features. Despite the ease of interpretation of multiple channel products, the combination of channels and channel differences means the resulting product does not represent a quantity or physical parameter such as brightness temperature in conventional single channel satellite imagery. Without a specific quantity to reference, forecasters are often confused as to what RGB products represent. Hyperspectral infrared retrieved profiles of temperature, moisture, and ozone can provide insight about the air mass represented on the RGB Air Mass product and provide confidence in the product and representation of air masses despite the lack of a quantity to reference for interpretation. This study focuses on RGB Air Mass analysis of Hurricane Sandy as it moved north along the U.S. East Coast, while transitioning to a hybrid extratropical storm. Soundings and total column ozone retrievals were analyzed using data from the Cross-track Infrared and Advanced Technology Microwave Sounder Suite (CrIMSS) on the Suomi National Polar Orbiting Partnership satellite and the Atmospheric Infrared Sounder (AIRS) on the National Aeronautics and Space Administration Aqua satellite along with dropsondes that were collected from National Oceanic and Atmospheric Administration and Air Force research aircraft. By comparing these datasets to the RGB Air Mass, it is possible to capture quantitative information that could help in analyzing the synoptic environment enough to diagnose the onset of extratropical transition. This was done by identifying any stratospheric air intrusions (SAIs) that existed in the vicinity of Sandy as the wind

  18. Air Mass Origin in the Arctic and its Response to Future Warming

    NASA Technical Reports Server (NTRS)

    Orbe, Clara; Newman, Paul A.; Waugh, Darryn W.; Holzer, Mark; Oman, Luke; Polvani, Lorenzo M.; Li, Feng

    2014-01-01

    We present the first climatology of air mass origin in the Arctic in terms of rigorously defined air mass fractions that partition air according to where it last contacted the planetary boundary layer (PBL). Results from a present-day climate integration of the GEOSCCM general circulation model reveal that the Arctic lower troposphere below 700 mb is dominated year round by air whose last PBL contact occurred poleward of 60degN, (Arctic air, or air of Arctic origin). By comparison, approx. 63% of the Arctic troposphere above 700 mb originates in the NH midlatitude PBL, (midlatitude air). Although seasonal changes in the total fraction of midlatitude air are small, there are dramatic changes in where that air last contacted the PBL, especially above 700 mb. Specifically, during winter air in the Arctic originates preferentially over the oceans, approx. 26% in the East Pacific, and approx. 20% in the Atlantic PBL. By comparison, during summer air in the Arctic last contacted the midlatitude PBL primarily over land, overwhelmingly so in Asia (approx. 40 %) and, to a lesser extent, in North America (approx. 24%). Seasonal changes in air-mass origin are interpreted in terms of seasonal variations in the large-scale ventilation of the midlatitude boundary layer and lower troposphere, namely changes in the midlatitude tropospheric jet and associated transient eddies during winter and large scale convective motions over midlatitudes during summer.

  19. Accelerator Mass Spectrometric determination of radiocarbon in stratospheric CO2, retrieved from AirCore sampling.

    NASA Astrophysics Data System (ADS)

    Paul, Dipayan; Been, Henk A.; Chen, Huilin; Kivi, Rigel; Meijer, Harro A. J.

    2015-04-01

    In this decade, understanding the impact of human activities on climate is one of the key issues of discussion globally. The continuous rise in the concentration of greenhouse gases, e.g., CO2, CH4, etc. in the atmosphere, predominantly due to human activities, is alarming and requires continuous monitoring to understand the dynamics. Radiocarbon is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases like CO2 and CH4. Measurement of 14C (or radiocarbon) in atmospheric CO2 generally requires collection of large air samples (few liters) from which CO2 is extracted and then the concentration of radiocarbon is determined. Currently, Accelerator Mass Spectrometry (AMS) is the most precise, reliable and widely used technique for atmospheric radiocarbon detection. However, the regular collection of air samples from troposphere and stratosphere, for example using aircraft, is prohibitively expensive. AirCore is an innovative atmospheric sampling system, developed by NOAA. It comprises of a long tube descending from a high altitude with one end open and the other closed, and has been demonstrated to be a reliable, cost-effective sampling system for high-altitude profile (up to ~ 30 km) measurements of CH4and CO2(Karion et al. 2010). In Europe, AirCore measurements are being performed on a regular basis near Sodankylä since September 2013. Here we describe the analysis of two such AirCore samples collected in July 2014, Finland, for determining the 14C concentration in stratospheric CO2. The two AirCore samples were collected on consecutive days. Each stratospheric AirCore sample was divided into six fractions, each containing ~ 35 μg CO2 (~9.5 μg C). Each fraction was separately trapped in 1 /4 inch coiled stainless steel tubing for radiocarbon measurements. The procedure for CO2 extraction from the stratospheric air samples; the sample preparation, with samples containing < 10

  20. Ozone Modulation/Membrane Introduction Mass Spectrometry for Analysis of Hydrocarbon Pollutants in Air

    NASA Astrophysics Data System (ADS)

    Atkinson, D. B.

    2001-12-01

    Modulation of volatile hydrocarbons in two-component mixtures is demonstrated using an ozonolysis pretreatment with membrane introduction mass spectrometry (MIMS). The MIMS technique allows selective introduction of volatile and semivolatile analytes into a mass spectrometer via processes known collectively as pervaporation [Kotiaho and Cooks, 1992]. A semipermeable polymer membrane acts as an interface between the sample (vapor or solution) and the vacuum of the mass spectrometer. This technique has been demonstrated to allow for sensitive analysis of hydrocarbons and other non-polar volatile organic compounds (VOC`s) in air samples[Cisper et al., 1995] . The methodology has the advantages of no sample pretreatment and short analysis time, which are promising for online monitoring applications but the chief disadvantage of lack of a separation step for the different analytes in a mixture. Several approaches have been investigated to overcome this problem including use of selective chemical ionization [Bier and Cooks, 1987] and multivariate calibration techniques[Ketola et al., 1999] . A new approach is reported for the quantitative measurement of VOCs in complex matrices. The method seeks to reduce the complexity of mass spectra observed in hydrocarbon mixture analysis by selective pretreatment of the analyte mixture. In the current investigation, the rapid reaction of ozone with alkenes is used, producing oxygenated compounds which are suppressed by the MIMS system. This has the effect of removing signals due to unsaturated analytes from the compound mass spectra, and comparison of the spectra before and after the ozone treatment reveals the nature of the parent compounds. In preliminary investigations, ozone reacted completely with cyclohexene from a mixture of cylohexene and cyclohexane, and with β -pinene from a mixture of toluene and β -pinene, suppressing the ion signals from the olefins. A slight attenuation of the cyclohexane and toluene in those

  1. Assessment of the impact on the air environment due to opencast coal mining — an Indian case study

    NASA Astrophysics Data System (ADS)

    Ghose, M. K.; Majee, S. R.

    The Indian reserve of coking coal is mainly located in the Jharia Coalfield (JCF) of Bharat Coking Coal Ltd. (BCCL). The reserves which are 19 339 Mt, have been exploited intensely over the last 80 yr. Resulting air pollution is increasing in the area due to large-scale opencast (O/C) mining. But no well-defined method of estimating the generation of air pollutants is used due to different mining activities. An investigation has been conducted to evaluate the air pollution due to a large O/C coal project. The mining project under study is one of the largest opencast projects (OCP) of BCCL and the details have been described. Ambient air monitoring stations were chosen considering the dominant wind directions (upwind and downwind) and covering industrial, residential and sensitive zones. The air quality survey was carried out for four seasons and the methodology adopted has been described. The data revealed a high air pollution potential and are in respect of suspended particulate matter (SPM) and respirable particulate matter (RPM) in the project area as well as in the surrounding locations. Impacts on the air quality have been assessed on the basis of upwind and downwind concentration of air pollutants.

  2. Fatal postpartum air embolism due to uterine inversion and atonic hemorrhage.

    PubMed

    Banaschak, Sibylle; Janßen, Katharina; Becker, Katrin; Friedrich, Krischan; Rothschild, Markus A

    2014-01-01

    We report a case of a 19-year-old woman who developed a persistent uterine hemorrhage after spontaneous delivery of a healthy child. Emergency laparotomy was indicated and then begun under stable circulatory conditions. Cardiac arrest occurred during the course of massive manual compression and packing of the uterus. After successful resuscitation, a supracervical hysterectomy was performed. During the suturing of the remaining cervix, a second cardiac arrest followed. The procedure was completed under constant external heart massage. Resuscitation was terminated due to the persistence of widened pupils. An autopsy was ordered by the public prosecutor as the manner of death was declared to be unascertained. An X-ray and a CT scan prior to the autopsy showed extensive gas embolism in both arterial and venous vessels extending from the pelvic region to the head. During the autopsy, gas was collected by aspirometer from the right ventricle of the heart. The autopsy showed no additional relevant findings, and gas analysis confirmed the suspicion of air embolism. The histological examination of the excised uterus especially in the corpus/fundus revealed an edema of the local smooth muscle cells and dilated vessels showing no sign of thrombogenesis. Upon evaluation of the clinical records, it became evident that, in addition to uterine atony, there had been a complete uterine inversion. This inversion was manually repositioned. After this maneuver, manual compression was performed. The air embolism, thus, was a complication of the manual repositioning of the uterine inversion. There is no evidence for other possible entries of the detected gas. In order to perform an effective exploration, the availability of all clinical records should be mandatory for medico-legal investigations of unexpected postpartum deaths. PMID:23370575

  3. Does the mass of a black hole decrease due to the accretion of phantom energy?

    SciTech Connect

    Gao Changjun; Chen Xuelei; Faraoni, Valerio; Shen Yougen

    2008-07-15

    According to Babichev et al., the accretion of a phantom test fluid onto a Schwarzschild black hole will induce the mass of the black hole to decrease, however the backreaction was ignored in their calculation. Using new exact solutions describing black holes in a background Friedmann-Robertson-Walker universe, we find that the physical black hole mass may instead increase due to the accretion of phantom energy. If this is the case, and the future universe is dominated by phantom dark energy, the black hole apparent horizon and the cosmic apparent horizon will eventually coincide and, after that, the black hole singularity will become naked in finite comoving time before the big rip occurs, violating the cosmic censorship conjecture.

  4. Changes in tropospheric composition and air quality due to stratospheric ozone depletion.

    PubMed

    Solomon, Keith R; Tang, Xiaoyan; Wilson, Stephen R; Zanis, Prodromos; Bais, Alkiviadis F

    2003-01-01

    Increased UV-B through stratospheric ozone depletion leads to an increased chemical activity in the lower atmosphere (the troposphere). The effect of stratospheric ozone depletion on tropospheric ozone is small (though significant) compared to the ozone generated anthropogenically in areas already experiencing air pollution. Modeling and experimental studies suggest that the impacts of stratospheric ozone depletion on tropospheric ozone are different at different altitudes and for different chemical regimes. As a result the increase in ozone due to stratospheric ozone depletion may be greater in polluted regions. Attributable effects on concentrations are expected only in regions where local emissions make minor contributions. The vertical distribution of NOx (NO + NO2), the emission of volatile organic compounds and the abundance of water vapor, are important influencing factors. The long-term nature of stratospheric ozone depletion means that even a small increase in tropospheric ozone concentration can have a significant impact on human health and the environment. Trifluoroacetic acid (TFA) and chlorodifluoroacetic acid (CDFA) are produced by the atmospheric degradation of hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). TFA has been measured in rain, rivers, lakes, and oceans, the ultimate sink for these and related compounds. Significant anthropogenic sources of TFA other than degradation HCFCs and HFCs have been identified. Toxicity tests under field conditions indicate that the concentrations of TFA and CDFA currently produced by the atmospheric degradation of HFCs and HCFCs do not present a risk to human health and the environment. The impact of the interaction between ozone depletion and future climate change is complex and a significant area of current research. For air quality and tropospheric composition, a range of physical parameters such as temperature, cloudiness and atmospheric transport will modify the impact of UV-B. Changes in the

  5. Disease burden due to biomass cooking-fuel-related household air pollution among women in India

    PubMed Central

    Sehgal, Meena; Rizwan, Suliankatchi Abdulkader; Krishnan, Anand

    2014-01-01

    Background Household air pollution (HAP) due to biomass cooking fuel use is an important risk factor for a range of diseases, especially among adult women who are primary cooks, in India. About 80% of rural households in India use biomass fuel for cooking. The aim of this study is to estimate the attributable cases (AC) for four major diseases/conditions associated with biomass cooking fuel use among adult Indian women. Methods We used the population attributable fraction (PAF) method to calculate the AC of chronic bronchitis, tuberculosis (TB), cataract, and stillbirths due to exposure to biomass cooking fuel. A number of data sources were accessed to obtain population totals and disease prevalence rates. A meta-analysis was conducted to obtain adjusted pooled odds ratios (ORs) for strength of association. Using this, PAF and AC were calculated using a standard formula. Results were presented as number of AC and 95% confidence intervals (CI). Results The fixed effects pooled OR obtained from the meta-analysis were 2.37 (95% CI: 1.59, 3.54) for chronic bronchitis, 2.33 (1.65, 3.28) for TB, 2.16 (1.42, 3.26) for cataract, and 1.26 (1.12, 1.43) for stillbirths. PAF varied across conditions being maximum (53%) for chronic bronchitis in rural areas and least (1%) for cataract in older age and urban areas. About 2.4 (95% CI: 1.4, 3.1) of 5.6 m cases of chronic bronchitis, 0.3 (0.2, 0.4) of 0.76 m cases of TB, 5.0 (2.8, 6.7) of 51.4 m cases of cataract among adult Indian women and 0.02 (0.01, 0.03) of 0.15 m stillbirths across India are attributable to HAP due to biomass cooking fuel. These estimates should be cautiously interpreted in the light of limitations discussed which relate to exposure assessment, exposure characterization, and age-specific prevalence of disease. Conclusions HAP due to biomass fuel has diverse and major impacts on women’s health in India. Although challenging, incorporating the agenda of universal clean fuel access or cleaner technology within

  6. Damage costs due to automotive air pollution and the influence of street canyons

    NASA Astrophysics Data System (ADS)

    Spadaro, Joseph V.; Rabl, Ari

    Using the methodology of the ExternE Project of the European Commission, we have evaluated the damage costs of automotive air pollution by way of two case studies in France: a trip across Paris, and a trip from Paris to Lyon. This methodology involves an analysis of the impact pathways, starting with the emissions (e.g., g/km of particles from tailpipe), followed by local and regional dispersion (e.g., incremental μg/m 3 of particles), calculation of the physical impacts using exposure-response functions (e.g., cases of respiratory hospital admissions), and finally multiplication by unit costs factors (e.g., ? per hospital admission). Damages are aggregated over all affected receptors in Europe. In addition to the local and regional dispersion calculations carried out so far by ExternE, we also consider the increased microscale impacts due to the trapping of pollutants in street canyons, using numerical simulations with the FLUENT software. We have evaluated impacts to human health, agricultural crops and building materials, due to particles, NO x, CO, HC and CO 2. Health impacts, especially reduced life expectancy, dominate in terms of cost. Damages for older cars (before 1997) range from 2 to 41 Euro cents/km, whereas for newer cars (since 1997), the range 1-9 Euro cents/km, and there is continuing progress in reducing the emissions further. In large cities, the particulate emissions of diesel cars lead to the highest damages, exceeding those of gasoline cars by a factor of 7. For cars before 1997 the order of magnitude of the damage costs is comparable to the price of gasoline, and the loss of life expectancy is comparable to that from traffic accidents.

  7. Prediction of health risk due to polycyclic aromatic hydrocarbons present in urban air in Rio de Janeiro, Brazil.

    PubMed

    Rainho, C R; Velho, A M A; Corrêa, S M; Mazzei, J L; Aiub, C A F; Felzenszwalb, I

    2013-01-01

    Risk assessment can provide a comprehensive estimate of potential effects of contaminants under specific, well-defined, and well-described circumstances, providing quantitative relationships between exposure and effects to identify and to define areas of concern. We investigated the mutagenic activity of particulate matter in air samples collected from three sites in Rio de Janeiro city. Samples were collected using a high-volume sampler at Avenida Brasil, at Campus of Universidade do Estado do Rio de Janeiro, and at Rebouças Tunnel. Six polycyclic aromatic hydrocarbons were quantified by gas chromatography/mass spectrometry. Salmonella typhimurium TA98 and the derivative strains TA98/1.8-DNP(6), YG1021, and YG1024, commonly used in mutagenicity assays, were treated (10-50 µg/plate), with and without exogenous metabolization. The highest values for the polycyclic aromatic hydrocarbons were detected at Rebouças Tunnel. For chrysene, as an example, the concentration was nearly 200 times higher than that established by the US Environmental Protection Agency. Frequent traffic jams can place bus drivers who go through the Rebouças Tunnel at risk of exposure to up to 0.69 ng/m(3) benzo(a) pyrene. Independent of exogenous metabolization, mutagenicity was detected in strains YG1021 and YG1024 at all the sites, suggesting nitro and amino derivatives of polycyclic aromatic hydrocarbons. Rebouças Tunnel air samples gave the highest values for rev/µg and rev/m(3). This could be due to the fact that the long, enclosed passageway through a mountain restricts ventilation. The cancer risk estimate in this study was 10(-3) for the benzo(a)pyrene, at the two sites, indicating a high risk. PMID:23479151

  8. The Analysis of PPM Levels of Gases in Air by Photoionization Mass Spectrometry

    ERIC Educational Resources Information Center

    Driscoll, John N.; Warneck, Peter

    1973-01-01

    Discusses analysis of trace gases in air by photoionization mass spectrometer. It is shown that the necessary sensitivity can be obtained by eliminating the UV monochromator and using direct ionization with a hydrogen light source. (JP)

  9. Deflection of light due to rotating mass - a comparison among the results of different approaches

    NASA Astrophysics Data System (ADS)

    Chakraborty, Sarani; Sen, Asoke Kumar

    2014-03-01

    It is known that light gets deflected due to mass. Value of deflection of light for static body is not same as it is in the case of rotating body. The deflection for a static body entirely depends on the gravitational mass where in case of a rotating body new terms will be included due to rotation. The bending angle of light is also not same in the equatorial plane and non equatorial plane for rotating Kerr body. The light bending angle is also direction of motion dependent i.e. if the motion of the light ray is in the direction of rotation, bending angle is greater than the static case and if the ray is in the opposite direction of rotation, the bending angle is smaller than the static case in equatorial plane. There are two approaches to obtain the bending angle, null geodesic of photon and change of effective refractive index. In this paper a comparison will be made among the results of different approaches.

  10. Changes in recovery due to drug product matrix ageing as a source of mass imbalances.

    PubMed

    Schulz, Katharina; Oberdieck, Ulrich; Backensfeld, Thomas; Weitschies, Werner

    2013-02-23

    An important quality feature of stability testing of drug products is mass balance. Besides several known or anticipated causes for mass imbalances, a further potential cause that has not yet been systematically assessed might be incomplete recovery due to the influence of matrix ageing. The genotoxic degradation product 4-chloroaniline (PCA) and the unstable drug substance estradiol (E2) that is known to be difficult to extract from matrices in low-dose solid formulations were chosen as examples. A marketed product containing E2 as well as two marketed products that potentially contain PCA were investigated together with experimental formulations containing E2 or PCA that were produced for this study. To accelerate drug product matrix ageing, samples were stored at different conditions for defined storage periods. PCA and E2 recovery was determined at all sampling time points, respectively. In comparison to unstressed samples, significant changes in recovery were observed in 67% of the formulations investigated. Consequently, the outlined procedure can be regarded as a promising approach to reveal potential reasons for mass imbalance. PMID:23245242

  11. Efficient modelling of gravity effects due to topographic masses using the Gauss-FFT method

    NASA Astrophysics Data System (ADS)

    Wu, Leyuan

    2016-04-01

    We present efficient Fourier-domain algorithms for modelling gravity effects due to topographic masses. The well-known Parker's formula originally based on the standard fast Fourier transform (FFT) algorithm is modified by applying the Gauss-FFT method instead. Numerical precision of the forward and inverse Fourier transforms embedded in Parker's formula and its extended forms are significantly improved by the Gauss-FFT method. The topographic model is composed of two major aspects, the geometry and the density. Versatile geometric representations, including the mass line model, the mass prism model, the polyhedron model and smoother topographic models interpolated from discrete data sets using high-order splines or pre-defined by analytical functions, in combination with density distributions that vary both laterally and vertically in rather arbitrary ways following exponential or general polynomial functions, now can be treated in a consistent framework by applying the Gauss-FFT method. The method presented has been numerically checked by space-domain analytical and hybrid analytical/numerical solutions already established in the literature. Synthetic and real model tests show that both the Gauss-FFT method and the standard FFT method run much faster than space-domain solutions, with the Gauss-FFT method being superior in numerical accuracy. When truncation errors are negligible, the Gauss-FFT method can provide forward results almost identical to space-domain analytical or semi-numerical solutions in much less time.

  12. FUNDAMENTAL MASS TRANSFER MODEL FOR INDOOR AIR EMISSION FROM SURFACE COATINGS

    EPA Science Inventory

    The paper, discusses the work of researchers at the U.S. EPA's Air and Energy Engineering Research Laboratory (Indoor Air Branch) who are evaluating mass transfer models based on fundamental principles to determine their effectiveness in predicting emissions from indoor architect...

  13. DNAPL REMOVAL MECHANISMS AND MASS TRANSFER CHARACTERISTICS DURING COSOLVENT-AIR FLOODING

    EPA Science Inventory

    The concurrent injection of cosolvent and air, a cosolvent-air (CA) flood was recently suggested for a dense nonaqueous phase liquid (DNAPL) remediation technology. The objectives of this study were to elucidate the DNAPL removal mechanisms of the CA flood and to quantify mass t...

  14. Experimental Determination of the Mass of Air Molecules from the Law of Atmospheres.

    ERIC Educational Resources Information Center

    Hayn, Carl H.; Galvin, Vincent, Jr.

    1979-01-01

    A gas pressure gauge has been constructed for use in a student experiment involving the law of atmospheres. From pressure data obtained at selected elevations the average mass of air molecules is determined and compared to that calculated from the molecular weights and percentages of constituents to the air. (Author/BB)

  15. Enhanced mass removal due to phase explosion during high irradiance nanosecond laser ablation of silicon

    SciTech Connect

    Yoo, Jong Hyun

    2000-05-20

    The morphology of craters resulting from high irradiance laser ablation of silicon was measured using a white light interferometry microscope. The craters show a dramatic increase in their depth and volume at a certain irradiance, indicating a change in the primary mechanism for mass removal. Laser shadowgraph imaging was used to characterize and differentiate the mass ejection processes for laser irradiances above and below the threshold value. Time-resolved images show distinct features of the mass ejected at irradiances above the threshold value including the presence of micron-sized particulates; this begins at approximately 300 {approx} 400 ns after the start of laser heating. The analysis of the phenomena was carried out by using two models: a thermal evaporation model and a phase explosion model. Estimation of the crater depth due to the thermally evaporated mass led to a large underestimation of the crater depth for irradiances above the threshold. Above the threshold irradiance, the possibility of phase explosion was analyzed. Two important results are the thickness of the superheated liquid layer that is close to the critical temperature and the time for vapor bubbles that are generated in the superheated liquid to achieve a critical size. After reaching the critical size, vapor bubbles can grow spontaneously resulting in a violent ejection of liquid droplets from the superheated volume. The effects of an induced transparency, i.e. of liquid silicon turning into an optically transparent liquid dielectric medium, are also introduced. The estimated time for a bubble to reach the critical size is in agreement with the delay time measured for the initiation of large mass ejection. Also, the thickness of the superheated liquid layer that is close to the critical temperature at the time of the beginning of the large mass ejection is representative of the crater depth at the threshold irradiance. These results suggest that phase explosion is a plausible thermal

  16. Permanent bilateral acoustic trauma due to air bag deployment in a young female adult.

    PubMed

    Kastanioudakis, Ioannis; Exarchakos, Georgios; Ziavra, Nausica; Skevas, Antonios

    2003-02-01

    Air bag safety systems have significantly reduced the number of occupant injuries from road traffic accidents (RTA). However air bag deployment is also associated with unavoidable risks. We report the acoustic trauma incurred by a young female driver who was a heavy smoker as a consequence of air-bag deployment in a low speed RTA and the sparing of her child seated in the rear. PMID:12625890

  17. 40 CFR 86.166-12 - Method for calculating emissions due to air conditioning leakage.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... determine a refrigerant leakage rate in grams per year from vehicle-based air conditioning units. The... using the following equation: Grams/YRTOT = Grams/YRRP + Grams/YRSP + Grams/YRFH + Grams/YRMC + Grams/YRC Where: Grams/YRTOT = Total air conditioning system emission rate in grams per year and rounded...

  18. Critical Mass Academic Planning. AIR Forum Paper 1978.

    ERIC Educational Resources Information Center

    Jones, Larry R.

    Methods of academic resource planning for research-oriented colleges and universities are explored. Focus is on resource allocation that is not strictly related to overall institutional enrollment level, but with the desirability of maintaining a minimum or "critical mass" levels of program breadth and quality. The purpose of critical mass…

  19. Energy enhancement and spectrum narrowing in terahertz electron sources due to negative mass instability

    NASA Astrophysics Data System (ADS)

    Lurie, Yu.; Bratman, V. L.; Savilov, A. V.

    2016-05-01

    Simulations of coherent spontaneous undulator radiation in a waveguide demonstrate that the use of negative mass instability (NMI) for retaining longitudinal sizes of dense electron bunches, which are formed in laser-driven photoinjectors, allows one to increase power capabilities of a terahertz radiation source by many times. The NMI is realized in an undulator with combined helical and over-resonance uniform longitudinal magnetic fields due to nonisochronous longitudinal oscillations of electrons, whose frequencies increase/decrease with increasing/decreasing particle energy. In such conditions, an effective longitudinal size of the bunches can be preserved at long distance even at an extremely high electron density. Correspondingly, an energy extraction efficiency of more than 20% is revealed at a narrow frequency radiation spectrum, suggesting realization of a compact and powerful THz source.

  20. Transfer of mass from Io to Europa and beyond due to cometary impacts

    NASA Astrophysics Data System (ADS)

    Alvarellos, José Luis; Zahnle, Kevin J.; Dobrovolskis, Anthony R.; Hamill, Patrick

    2008-04-01

    We simulate the production and orbital evolution of escaping ejecta due to cometary impacts on Io. The model includes the four Galilean satellites, Amalthea, Thebe, Jupiter's gravitational moments, Saturn and the Sun. Five scenarios are examined: an impact at the apex, the sub-jovian point, the anti-jovian point, the antapex, and at the south pole of Io. We estimate that on average a cometary impact injects thrice its mass (in the form of Io surface material) into jovicentric orbit. The majority of the escaping debris comes back to Io, but a sizeable fraction (between 5.0 and 8.7%) manages to reach Europa, and a smaller fraction Ganymede (between 1.5 and 4.6%). Smaller fractions reached Amalthea Thebe, Callisto, and Jupiter itself. For million year time scales, the mass transfer to Europa is estimated as 1.8-3.1×10 g/Myr. The median time for transfer of ejecta from Io to Europa is ˜56 years.

  1. Cardiac arrest during radical nephrectomy due to a mass in the right ventricular outflow tract.

    PubMed

    Kim, Hee Young; Baek, Seung-Hoon; Yoon, Ji Uk; Lee, Dong Hoon; Byeon, Gyeong-Jo; Ahn, Ji Hye

    2016-09-01

    We report cardiac arrest due to obstruction of the right ventricular outflow tract (RVOT) caused by an RVOT mass that was not identified preoperatively. A 62-year-old woman with renal cell carcinoma (RCC) experienced deteriorating hypotension and bradycardia during radical nephrectomy. Hemodynamic stability was maintained on extracorporeal membrane oxygenation, and after surgery, she was transferred to the intensive care unit. On postoperative day 3, transthoracic echocardiography showed an intracardiac mass obstructing the RVOT, which caused severe functional pulmonary stenosis and moderate resting pulmonary hypertension. Despite maintaining extracorporeal membrane oxygenation, the patient died of cardiac arrest. Our findings suggest that it may be necessary to perform additional tests if RCC has invaded the renal vein and inferior vena cava or if a patient with RCC has abnormal cardiovascular symptoms without definite etiology for exclusion of cardiac metastasis or tumor thrombus. In addition, intraoperative transesophageal echocardiography might be the procedure of choice for the evaluation of these conditions because other diagnostic tests are difficult to perform during surgery. In conclusion, for patients with acute hemodynamic instability for whom other possible causes have been excluded, we recommend that anesthesiologists use transesophageal echocardiography to detect outflow tract obstruction or pulmonary thromboembolism and perform anesthetic management. PMID:27555152

  2. The burden of COPD mortality due to ambient air pollution in Guangzhou, China.

    PubMed

    Li, Li; Yang, Jun; Song, Yun-Feng; Chen, Ping-Yan; Ou, Chun-Quan

    2016-01-01

    Few studies have investigated the chronic obstructive pulmonary disease (COPD) mortality fraction attributable to air pollution and modification by individual characteristics of air pollution effects. We applied distributed lag non-linear models to assess the associations between air pollution and COPD mortality in 2007-2011 in Guangzhou, China, and the total COPD mortality fraction attributable to air pollution was calculated as well. We found that an increase of 10 μg/m(3) in particulate matter with an aerodynamic diameter of 10 μm or less (PM10), sulfur dioxide (SO2) and nitrogen dioxide (NO2) was associated with a 1.58% (95% confidence interval (CI): 0.12-3.06%), 3.45% (95% CI: 1.30-5.66%) and 2.35% (95% CI: 0.42-4.32%) increase of COPD mortality over a lag of 0-15 days, respectively. Greater air pollution effects were observed in the elderly, males and residents with low educational attainment. The results showed 10.91% (95% CI: 1.02-9.58%), 12.71% (95% CI: 5.03-19.85%) and 13.38% (95% CI: 2.67-22.84%) COPD mortality was attributable to current PM10, SO2 and NO2 exposure, respectively. In conclusion, the associations between air pollution and COPD mortality differed by individual characteristics. There were remarkable COPD mortality burdens attributable to air pollution in Guangzhou. PMID:27195597

  3. The burden of COPD mortality due to ambient air pollution in Guangzhou, China

    NASA Astrophysics Data System (ADS)

    Li, Li; Yang, Jun; Song, Yun-Feng; Chen, Ping-Yan; Ou, Chun-Quan

    2016-05-01

    Few studies have investigated the chronic obstructive pulmonary disease (COPD) mortality fraction attributable to air pollution and modification by individual characteristics of air pollution effects. We applied distributed lag non-linear models to assess the associations between air pollution and COPD mortality in 2007–2011 in Guangzhou, China, and the total COPD mortality fraction attributable to air pollution was calculated as well. We found that an increase of 10 μg/m3 in particulate matter with an aerodynamic diameter of 10 μm or less (PM10), sulfur dioxide (SO2) and nitrogen dioxide (NO2) was associated with a 1.58% (95% confidence interval (CI): 0.12–3.06%), 3.45% (95% CI: 1.30–5.66%) and 2.35% (95% CI: 0.42–4.32%) increase of COPD mortality over a lag of 0–15 days, respectively. Greater air pollution effects were observed in the elderly, males and residents with low educational attainment. The results showed 10.91% (95% CI: 1.02–9.58%), 12.71% (95% CI: 5.03–19.85%) and 13.38% (95% CI: 2.67–22.84%) COPD mortality was attributable to current PM10, SO2 and NO2 exposure, respectively. In conclusion, the associations between air pollution and COPD mortality differed by individual characteristics. There were remarkable COPD mortality burdens attributable to air pollution in Guangzhou.

  4. Aerial observations of air masses transported from East Asia to the Western Pacific: Vertical structure of polluted air masses

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Shiro; Ikeda, Keisuke; Hanaoka, Sayuri; Watanabe, Izumi; Arakaki, Takemitsu; Bandow, Hiroshi; Sadanaga, Yasuhiro; Kato, Shungo; Kajii, Yoshizumi; Zhang, Daizhou; Okuyama, Kikuo; Ogi, Takashi; Fujimoto, Toshiyuki; Seto, Takafumi; Shimizu, Atsushi; Sugimoto, Nobuo; Takami, Akinori

    2014-11-01

    There has been only limited information about the vertical chemical structure of the atmosphere, so far. We conducted aerial observations on 11, 12, and 14 December 2010 over the northern part of the East China Sea to analyze the spatial distribution of atmospheric pollutants from East Asia and to elucidate transformation processes of air pollutants during the long-range transport. On 11 December, a day on which Asian dust created hazy conditions, the average PM10 concentration was 40.69 μg m-3, and we observed high concentrations of chemical components such as Ca2+, NO3-, SO42-, Al, Ca, Fe, and Zn. The height of the boundary layer was about 1200 m, and most species of pollutants (except for dust particles and SO2) had accumulated within the boundary layer. In contrast, concentrations of pollutants were low in the boundary layer (up to 1000 m) on 12 December because clean Pacific air from the southeast had diluted the haze. However, we observed natural chemical components (Na+, Cl-, Al, Ca, and Fe) at 3000 m, the indication being that dust particles, including halite, were present in the lower free troposphere. On 14 December, peak concentrations of SO2 and black carbon were measured within the boundary layer (up to 700 m) and at 2300 m. The concentrations of anthropogenic chemical components such as NO3-, NH4+, and Zn were highest at 500 m, and concentrations of both anthropogenic and natural chemical components (SO42-, Pb, Ca2+, Ca, Al, and Fe) were highest at 2000 m. Thus, it was clearly indicated that the air above the East China Sea had a well-defined, layered structure below 3000 m.

  5. The burden of COPD mortality due to ambient air pollution in Guangzhou, China

    PubMed Central

    Li, Li; Yang, Jun; Song, Yun-Feng; Chen, Ping-Yan; Ou, Chun-Quan

    2016-01-01

    Few studies have investigated the chronic obstructive pulmonary disease (COPD) mortality fraction attributable to air pollution and modification by individual characteristics of air pollution effects. We applied distributed lag non-linear models to assess the associations between air pollution and COPD mortality in 2007–2011 in Guangzhou, China, and the total COPD mortality fraction attributable to air pollution was calculated as well. We found that an increase of 10 μg/m3 in particulate matter with an aerodynamic diameter of 10 μm or less (PM10), sulfur dioxide (SO2) and nitrogen dioxide (NO2) was associated with a 1.58% (95% confidence interval (CI): 0.12–3.06%), 3.45% (95% CI: 1.30–5.66%) and 2.35% (95% CI: 0.42–4.32%) increase of COPD mortality over a lag of 0–15 days, respectively. Greater air pollution effects were observed in the elderly, males and residents with low educational attainment. The results showed 10.91% (95% CI: 1.02–9.58%), 12.71% (95% CI: 5.03–19.85%) and 13.38% (95% CI: 2.67–22.84%) COPD mortality was attributable to current PM10, SO2 and NO2 exposure, respectively. In conclusion, the associations between air pollution and COPD mortality differed by individual characteristics. There were remarkable COPD mortality burdens attributable to air pollution in Guangzhou. PMID:27195597

  6. Lamination of pharmaceutical tablets due to air entrapment: direct visualization and influence of the compact thickness.

    PubMed

    Mazel, V; Busignies, V; Diarra, H; Tchoreloff, P

    2015-01-30

    Capping and lamination are two problems that are often faced during the industrial manufacturing of pharmaceutical tablets. Several reasons have been proposed to explain these phenomena. Among them, air entrapment is supposed to play a role in some cases. Nevertheless, no direct proof were given to prove that air entrapment can promote lamination or capping and various publications have questioned this hypothesis. In this article, using a model product compacted on a compression simulator, a direct proof of the implication of air entrapment during lamination was given. In fact, at the surface of the compact, defects with a spherical shape, clearly linked with an entrapped bubble of air, began to appear on the surface of the compact just below the pressure level to which lamination was observed. Moreover it was also observed that, when the compact thickness increased, the lamination pressure decreased, meaning that the compact thickness can promote lamination. As a conclusion, contrary to what is said in some publications, air entrapment can be involved when problems of lamination occur, and, in this case, powder desaeration should be considered. PMID:25522829

  7. Paradoxical air embolism during percutaneous nephrolithotomy due to patent foramen ovale: Case report

    PubMed Central

    Chahal, Daljeet; Ruzhynsky, Vladimir; McAuley, Iain; Sweeney, Desmond; Sobkin, Paul; Kinahan, Michael; Gardiner, Rich; Kinahan, John

    2015-01-01

    Paradoxical air embolism is a very rare complication associated with percutaneous nephrolithotomy (PCNL). Incidence may be higher if patients also suffer from a septal heart defect. We report the case of a 76-year old male who presented for PCNL treatment of a right kidney lower calyceal calculus. During the procedure, the patient developed signs and symptoms consistent with that of air embolism. Intraoperative echocardiography confirmed the diagnosis. Subsequent intraoperative and postoperative medical management was carried out and the patient was discharged after recovery three days later. This case highlights the importance of a rare but potentially fatal complication of PCNL. PMID:26425235

  8. Technology Solutions Case Study: Overcoming Comfort Issues Due to Reduced Flow Room Air Mixing

    SciTech Connect

    2015-03-01

    Energy efficiency upgrades reduce heating and cooling loads on a house. With enough load reduction and if the HVAC system warrants replacement, the HVAC system is often upgraded with a more efficient, lower capacity system that meets the loads of the upgraded house. In this project, IBACOS studied when HVAC equipment is downsized and ducts are unaltered to determine conditions that could cause a supply air delivery problem and to evaluate the feasibility of modifying the duct systems using minimally invasive strategies to improve air distribution.

  9. Characteristics of tyre dust in polluted air: Studies by single particle mass spectrometry (ATOFMS)

    NASA Astrophysics Data System (ADS)

    Dall'Osto, Manuel; Beddows, David C. S.; Gietl, Johanna K.; Olatunbosun, Oluremi A.; Yang, Xiaoguang; Harrison, Roy M.

    2014-09-01

    There is a paucity of quantitative knowledge on the contributions of non-exhaust (abrasion and re-suspension) sources to traffic emissions. Abrasive emissions can be broadly categorised as tyre wear, brake wear and road dust/road surface wear. Current research often considers road dust and tyre dust as externally mixed particles, the former mainly composed of mineral matter and the latter solely composed of mainly organic matter and some trace elements. The aim of this work was to characterise tyre wear from both laboratory and field studies by using Aerosol Time-Of-Flight Mass Spectrometry (ATOFMS). Real-time single particle chemical composition was obtained from a set of rubber tyres rotating on a metal surface. Bimodal particle number size distributions peaking at 35 nm and 85 nm were obtained from SMPS/APS measurements over the range 6-20,000 nm. ATOFMS mass spectra of tyre wear in the particle size range 200-3000 nm diameter show peaks due to exo-sulphur compounds, nitrate, Zn and ions of high molecular weight (m/z > 100) attributed to organic polymers. Two large ATOFMS datasets collected from a number of outdoor studies were examined. The former was constituted of 48 road dust samples collected on the roads of London. The latter consisted of ATOFMS ambient air field studies from Europe, overall composed of more than 2,000,000 single particle mass spectra. The majority (95%) of tyre wear particles present in the road dust samples and atmospheric samples are internally mixed with metals (Li, Na, Ca, Fe, Ti), as well as phosphate. It is concluded that the interaction of tyres with the road surface creates particles internally mixed from two sources: tyre rubber and road surface materials. Measurements of the tyre rubber component alone may underestimate the contribution of tyre wear to concentrations of airborne particulate matter. The results presented are especially relevant for urban aerosol source apportionment and PM2.5 exposure assessment.

  10. Kinematically Accelerated Repulsions Due to Relative Motion between Mass Particles in an Accelerating Universe

    NASA Astrophysics Data System (ADS)

    Savickas, David

    2016-03-01

    An accelerated expansion of the universe, due only to relative particle motion, is described here in the form of a particular model that illustrates its physical cause. A simplified three particle universe is considered here by defining coordinate positions for effective mass-points because their size is extremely small compared to the distances between them. The three particles initially form a static isosceles triangular configuration. The third particle at the triangle's apex could only then determine its position relative to the triangle by measuring the apex angle subtended by the base particles. If the two base particles then exert for an instant a force between only themselves, they will move away from each other while the third particle could physically maintain its position relative to the universe only by referring to these other two existing particles. It would then be required that the apex particle would accelerate outwards and away from the base particles in order to regain the smaller size of the original apex angle and subsequently generate a Hubble expansion for the particles.

  11. Air quality and climate impacts due to CNG conversion of motor vehicles in Dhaka, Bangladesh.

    PubMed

    Wadud, Zia; Khan, Tanzila

    2013-12-17

    Dhaka had recently experienced rapid conversion of its motor vehicle fleet to run on compressed natural gas (CNG). This paper quantifies ex-post the air quality and climate benefits of the CNG conversion policy, including monetary valuations, through an impact pathway approach. Around 2045 (1665) avoided premature deaths in greater Dhaka (City Corporation) can be attributed to air quality improvements from the CNG conversion policy in 2010, resulting in a saving of around USD 400 million. Majority of these health benefits resulted from the conversion of high-emitting diesel vehicles. CNG conversion was clearly detrimental from climate change perspective using the changes in CO2 and CH4 only (CH4 emissions increased); however, after considering other global pollutants (especially black carbon), the climate impact was ambiguous. Uncertainty assessment using input distributions and Monte Carlo simulation along with a sensitivity analysis show that large uncertainties remain for climate impacts. For our most likely estimate, there were some climate costs, valued at USD 17.7 million, which is an order of magnitude smaller than the air quality benefits. This indicates that such policies can and should be undertaken on the grounds of improving local air pollution alone and that precautions should be taken to reduce the potentially unintended increases in GHG emissions or other unintended effects. PMID:24195736

  12. Thin-Film Air-Mass-Flow Sensor of Improved Design Developed

    NASA Technical Reports Server (NTRS)

    Fralick, Gustave C.; Wrbanek, John D.; Hwang, Danny P.

    2003-01-01

    Researchers at the NASA Glenn Research Center have developed a new air-mass-flow sensor to solve the problems of existing mass flow sensor designs. NASA's design consists of thin-film resistors in a Wheatstone bridge arrangement. The resistors are fabricated on a thin, constant-thickness airfoil to minimize disturbance to the airflow being measured. The following photograph shows one of NASA s prototype sensors. In comparison to other air-mass-flow sensor designs, NASA s thin-film sensor is much more robust than hot wires, causes less airflow disturbance than pitot tubes, is more accurate than vane anemometers, and is much simpler to operate than thermocouple rakes. NASA s thin-film air-mass-flow sensor works by converting the temperature difference seen at each leg of the thin-film Wheatstone bridge into a mass-flow rate. The following figure shows a schematic of this sensor with air flowing around it. The sensor operates as follows: current is applied to the bridge, which increases its temperature. If there is no flow, all the arms are heated equally, the bridge remains in balance, and there is no signal. If there is flow, the air passing over the upstream legs of the bridge reduces the temperature of the upstream legs and that leads to reduced electrical resistance for those legs. After the air has picked up heat from the upstream legs, it continues and passes over the downstream legs of the bridge. The heated air raises the temperature of these legs, increasing their electrical resistance. The resistance difference between the upstream and downstream legs unbalances the bridge, causing a voltage difference that can be amplified and calibrated to the airflow rate. Separate sensors mounted on the airfoil measure the temperature of the airflow, which is used to complete the calculation for the mass of air passing by the sensor. A current application for air-mass-flow sensors is as part of the intake system for an internal combustion engine. A mass-flow sensor is

  13. Influence of trans-boundary biomass burning impacted air masses on submicron particle number concentrations and size distributions

    NASA Astrophysics Data System (ADS)

    Betha, Raghu; Zhang, Zhe; Balasubramanian, Rajasekhar

    2014-08-01

    Submicron particle number concentration (PNC) and particle size distribution (PSD) in the size range of 5.6-560 nm were investigated in Singapore from 27 June 2009 through 6 September 2009. Slightly hazy conditions lasted in Singapore from 6 to 10 August. Backward air trajectories indicated that the haze was due to the transport of biomass burning impacted air masses originating from wild forest and peat fires in Sumatra, Indonesia. Three distinct peaks in the morning (08:00-10:00), afternoon (13:00-15:00) and evening (16:00-20:00) were observed on a typical normal day. However, during the haze period no distinct morning and afternoon peaks were observed and the PNC (39,775 ± 3741 cm-3) increased by 1.5 times when compared to that during non-haze periods (26,462 ± 6017). The morning and afternoon peaks on the normal day were associated with the local rush hour traffic while the afternoon peak was induced by new particle formation (NPF). Diurnal profiles of PNCs and PSDs showed that primary particle peak diameters were large during the haze (60 nm) period when compared to that during the non-haze period (45.3 nm). NPF events observed in the afternoon period on normal days were suppressed during the haze periods due to heavy particle loading in atmosphere caused by biomass burning impacted air masses.

  14. Interaction of mid-latitude air masses with the polar dome area during RACEPAC and NETCARE

    NASA Astrophysics Data System (ADS)

    Bozem, Heiko; Hoor, Peter; Koellner, Franziska; Kunkel, Daniel; Schneider, Johannes; Schulz, Christiane; Herber, Andreas; Borrmann, Stephan; Wendisch, Manfred; Ehrlich, Andre; Leaitch, Richard; Willis, Megan; Burkart, Julia; Thomas, Jennie; Abbatt, Jon

    2016-04-01

    We present aircraft based trace gas measurements in the Arctic during RACEPAC (2014) and NETCARE (2014 and 2015) with the Polar 6 aircraft of Alfred Wegener Institute (AWI) covering an area from 134°W to 17°W and 68°N to 83°N. We focus on cloud, aerosol and general transport processes of polluted air masses into the high Arctic. Based on CO and CO2 measurements and kinematic 10-day back trajectories as well as Flexpart particle dispersion modeling we analyze the transport regimes of mid-latitude air masses traveling to the high Arctic prevalent during spring (RACEPAC 2014, NETCARE 2015) and summer (NETCARE 2014). In general more northern parts of the high Arctic (Lat > 75°N) were relatively unaffected from mid-latitude air masses. In contrast, regions further south are influenced by air masses from Asia and Russia (eastern part of Canadian Arctic and European Arctic) as well as from North America (central and western parts of Canadian Arctic). The transition between the mostly isolated high Arctic and more southern regions indicated by tracer gradients is remarkably sharp. This allows for a chemical definition of the Polar dome based on the variability of CO and CO2 as a marker. Isentropic surfaces that slope from the surface to higher altitudes in the high Arctic form the polar dome that represents a transport barrier for mid-latitude air masses to enter the lower troposphere in the high Arctic. Synoptic-scale weather systems frequently disturb this transport barrier and foster the exchange between air masses from the mid-latitudes and polar regions. This can finally lead to enhanced pollution levels in the lower polar troposphere. Mid-latitude pollution plumes from biomass burning or flaring entering the polar dome area lead to an enhancement of 30% of the observed CO mixing ratio within the polar dome area.

  15. Numerical investigation of interfacial transport resistance due to water droplets in proton exchange membrane fuel cell air channels

    NASA Astrophysics Data System (ADS)

    Koz, Mustafa; Kandlikar, Satish G.

    2013-12-01

    Oxygen transport resistance at the air flow channel and gas diffusion layer (GDL) interface is needed in modelling the performance of a proton exchange membrane fuel cell (PEMFC). This resistance is expressed through the non-dimensional Sherwood number (Sh). The effect of the presence of a droplet on Sh is studied numerically in an isolated air flow channel using a commercially available package, COMSOL Multiphysics®. A droplet is represented as a solid obstruction placed on the GDL-channel interface and centred along the channel width. The effect of a single droplet is first studied for a range of superficial mean air velocities and droplet sizes. Secondly, the effect of droplet spacing on Sh is studied through simulations of two consecutive droplets. Lastly, multiple droplets in a row are studied as a more representative case of a PEMFC air flow channel. The results show that the droplets significantly increase Sh above the fully developed value in the wake region. This enhancement increases with the number of droplets, droplet size, and superficial mean air velocity. Moreover, the analogy between mass and heat transfer is investigated by comparing Sh to the equivalent Nusselt number.

  16. Air mass flow estimation in turbocharged diesel engines from in-cylinder pressure measurement

    SciTech Connect

    Desantes, J.M.; Galindo, J.; Guardiola, C.; Dolz, V.

    2010-01-15

    Air mass flow determination is needed for the control of current internal combustion engines. Current methods are based on specific sensors (as hot wire anemometers) or indirect estimation through manifold pressure. With the availability of cylinder pressure sensors for engine control, methods based on them can be used for replacing or complementing standard methods. Present paper uses in cylinder pressure increase during the intake stroke for inferring the trapped air mass. The method is validated on two different turbocharged diesel engines and compared with the standard methods. (author)

  17. Apparatus and method for generating large mass flow of high temperature air at hypersonic speeds

    NASA Technical Reports Server (NTRS)

    Sabol, A. P.; Stewart, R. B. (Inventor)

    1973-01-01

    High temperature, high mass air flow and a high Reynolds number test air flow in the Mach number 8-10 regime of adequate test flow duration is attained by pressurizing a ceramic-lined storage tank with air to a pressure of about 100 to 200 atmospheres. The air is heated to temperatures of 7,000 to 8,000 R prior to introduction into the tank by passing the air over an electric arc heater means. The air cools to 5,500 to 6,000 R while in the tank. A decomposable gas such as nitrous oxide or a combustible gas such as propane is injected into the tank after pressurization and the heated pressurized air in the tank is rapidly released through a Mach number 8-10 nozzle. The injected gas medium upon contact with the heated pressurized air effects an exothermic reaction which maintains the pressure and temperature of the pressurized air during the rapid release.

  18. The Use of Red Green Blue (RGB) Air Mass Imagery to Investigate the Role of Stratospheric Air in a Non-Convective Wind Event

    NASA Technical Reports Server (NTRS)

    Berndt, Emily; Zavodsky, Bradley; Molthan, Andrew; Jedlovec, Gary

    2013-01-01

    AIRS ozone and model PV analysis confirm the stratospheric air in RGB Air Mass imagery. Trajectories confirm winds south of the low were distinct from CCB driven winds. Cross sections connect the tropopause fold, downward motion, and high nearsurface winds. Comparison to conceptual models show Shapiro-Keyser features and sting jet characteristics were observed in a storm that impacted the U.S. East Coast. RGB Air Mass imagery can be used to identify stratospheric air and regions susceptible to tropopause folding and attendant non-convective winds.

  19. Fundamental mass transfer model for indoor air emissions from surface coatings

    SciTech Connect

    Tichenor, B.A.; Guo, Z.; Sparks, L.E.

    1994-01-01

    The paper discusses the work of researchers at the U.S. EPA's Air and Energy Engineering Research Laboratory (Indoor Air Branch) who are evaluating mass transfer models based on fundamental principles to determine their effectiveness in predicting emissions from indoor architectural coatings. As a first step, a simple model based on Fick's Law of Diffusion has been developed. In the model, the mass transfer rate is assumed to be controlled by the boundary layer mass transfer coefficient, the saturation vapor pressure of the material being emitted, and the mass of volatile material remaining in the source at any point in time. Both static and dynamic chamber tests were conducted to obtain model validation data. Further validation experiments were conducted in a test house. Results of these tests are presented.

  20. Air-Water Gas Exchange in Wetland Water Columns Due To Wind and Thermal Convection

    NASA Astrophysics Data System (ADS)

    Poindexter, C.; Variano, E. A.

    2011-12-01

    The goal of this work is to provide a parameterization of the air-water gas transfer rate in wetlands, and do so in terms of easily measured environmental variables. This parameterization is intended to support biogeochemical modeling in wetlands by providing an interfacial flux of key importance. Our approach uses laboratory experiments describe the oxygen transfer across an air-water interface in a model wetland. The oxygen transfer is sensitive to the externally imposed wind, vegetation characteristics, and vertical thermal convection. We vary these systematically, determining the gas transfer (or "piston") velocity that describes interfacial gas flux. We measure velocity vector fields near the air-water interface using particle image velocimetry, and use these measurements to help explain the mechanisms behind the measured trends in oxygen transfer. The explanatory power of these measurements includes the relationship between plant geometry and surface divergence. We explore the potential impact of our results on wetland modeling and management, for issues such as carbon sequestration and methane emission.

  1. Multimodel estimates of premature human mortality due to intercontinental transport of air pollution

    NASA Astrophysics Data System (ADS)

    Liang, C.; Silva, R.; West, J. J.; Sudo, K.; Lund, M. T.; Emmons, L. K.; Takemura, T.; Bian, H.

    2015-12-01

    Numerous modeling studies indicate that emissions from one continent influence air quality over others. Reducing air pollutant emissions from one continent can therefore benefit air quality and health on multiple continents. Here, we estimate the impacts of the intercontinental transport of ozone (O3) and fine particulate matter (PM2.5) on premature human mortality by using an ensemble of global chemical transport models coordinated by the Task Force on Hemispheric Transport of Air Pollution (TF HTAP). We use simulations of 20% reductions of all anthropogenic emissions from 13 regions (North America, Central America, South America, Europe, Northern Africa, Sub-Saharan Africa, Former Soviet Union, Middle East, East Asia, South Asia, South East Asia, Central Asia, and Australia) to calculate their impact on premature mortality within each region and elsewhere in the world. To better understand the impact of potential control strategies, we also analyze premature mortality for global 20% perturbations from five sectors individually: power and industry, ground transport, forest and savannah fires, residential, and others (shipping, aviation, and agriculture). Following previous studies, premature human mortality resulting from each perturbation scenario is calculated using a health impact function based on a log-linear model for O3 and an integrated exposure response model for PM2.5 to estimate relative risk. The spatial distribution of the exposed population (adults aged 25 and over) is obtained from the LandScan 2011 Global Population Dataset. Baseline mortality rates for chronic respiratory disease, ischemic heart disease, cerebrovascular disease, chronic obstructive pulmonary disease, and lung cancer are estimated from the GBD 2010 country-level mortality dataset for the exposed population. Model results are regridded from each model's original grid to a common 0.5°x0.5° grid used to estimate mortality. We perform uncertainty analysis and evaluate the sensitivity

  2. Remote mass spectrometric sampling of electrospray- and desorption electrospray-generated ions using an air ejector.

    PubMed

    Dixon, R Brent; Bereman, Michael S; Muddiman, David C; Hawkridge, Adam M

    2007-10-01

    A commercial air ejector was coupled to an electrospray ionization linear ion trap mass spectrometer (LTQ) to transport remotely generated ions from both electrospray (ESI) and desorption electrospray ionization (DESI) sources. We demonstrate the remote analysis of a series of analyte ions that range from small molecules and polymers to polypeptides using the AE-LTQ interface. The details of the ESI-AE-LTQ and DESI-AE-LTQ experimental configurations are described and preliminary mass spectrometric data are presented. PMID:17716909

  3. Remote Mass Spectrometric Sampling of Electrospray- and Desorption Electrospray-Generated Ions Using an Air Ejector

    PubMed Central

    Dixon, R. Brent; Bereman, Michael S.; Muddiman, David C.; Hawkridge, Adam M.

    2007-01-01

    A commercial air ejector was coupled to an electrospray ionization linear ion trap mass spectrometer (LTQ) to transport remotely generated ions from both electrospray (ESI) and desorption electrospray ionization (DESI) sources. We demonstrate the remote analysis of a series of analyte ions that range from small molecules and polymers to polypeptides using the AE-LTQ interface. The details of the ESI-AE-LTQ and DESI-AE-LTQ experimental configurations are described and preliminary mass spectrometric data is presented. PMID:17716909

  4. Pulseless electrical activity arrest due to air embolism during endoscopic retrograde cholangiopancreatography: a case report and review of the literature

    PubMed Central

    Mathew, Jacob; Parker, Calvin; Wang, James

    2015-01-01

    While most gastroenterologists are aware of the more common complications of endoscopy such as bleeding, infection and perforation, air embolism remains an under-recognised and difficult to diagnose problem due to its varying modes of presentation. This is the case of a 55-year-old man with right upper quadrant pain and imaging notable for cholecystitis and choledocholithiasis, who underwent endoscopic retrograde cholangiopancreatography (ERCP). During the ERCP, and shortly after a sphincterotomy was performed, he became hypotensive and hypoxic, quickly decompensating into pulseless electrical activity. While advanced cardiac life support was initiated, the patient passed away. Autopsy revealed air in the pulmonary artery suggestive of a pulmonary embolism. While air embolism remains a rare complication of upper endoscopy, increased awareness and prompt recognition of signs that may point to this diagnosis may potentially save lives by allowing for earlier possible interventions. PMID:26462286

  5. Risk assessment for cardiovascular and respiratory mortality due to air pollution and synoptic meteorology in 10 Canadian cities.

    PubMed

    Vanos, Jennifer K; Hebbern, Christopher; Cakmak, Sabit

    2014-02-01

    Synoptic weather and ambient air quality synergistically influence human health. We report the relative risk of mortality from all non-accidental, respiratory-, and cardiovascular-related causes, associated with exposure to four air pollutants, by weather type and season, in 10 major Canadian cities for 1981 through 1999. We conducted this multi-city time-series study using Poisson generalized linear models stratified by season and each of six distinctive synoptic weather types. Statistically significant relationships of mortality due to short-term exposure to carbon monoxide, nitrogen dioxide, sulphur dioxide, and ozone were found, with significant modifications of risk by weather type, season, and mortality cause. In total, 61% of the respiratory-related mortality relative risk estimates were significantly higher than for cardiovascular-related mortality. The combined effect of weather and air pollution is greatest when tropical-type weather is present in the spring or summer. PMID:24355413

  6. Is mudflow in Sidoarjo, East Java due to the pumping mechanism of hot air bubbles? : Laboratory simulations and field observations

    NASA Astrophysics Data System (ADS)

    Nurhandoko, Bagus Endar B.

    2015-09-01

    Extraordinary mudflow has happened in Sidoarjo, East Java, Indonesia since 2006. This mud comes from the giant crater that is located close to the BJP - 01. Thousands of homes have been submerged due to mudflow. Till today this giant mud crater is still has great strength despite the mud flowing over 8 years. This is a very rare phenomenon in the world. This mud flow mechanism raises big questions, because it has been going on for years, naturally the mudflow will stop by itself because the pressure should be reduced. This research evaluates all aspects of integrated observations, laboratory tests and field observations since the beginning of this ongoing mudflow. Laboratory tests were done by providing hot air bubbles into the fluid inside the inverted funnel showed that the fluid can flow with a high altitude. It is due to the mechanism of buoyant force from air bubbles to the water where the contrast density of the water and the air is quite large. Quantity of air bubbles provides direct effect to the debit of fluid flow. Direct observation in the field, in 2006 and 2007, with TIMNAS and LPPM ITB showed the large number of air bubbles on the surface of the mud craters. Temperature observation on the surface of mud crater is around 98 degree C whereas at greater depth shows the temperature is increasingly rising. This strengthens the hypothesis or proves that the mud pumping mechanism comes from buoyant force of hot air bubbles. Inversion gravity images show that the deep subsurface of main crater is close to volcanic layers or root of Arjuna mountain. Based on the simulation laboratory and field observation data, it can be concluded that the geothermal factor plays a key role in the mudflow mechanism.

  7. ANESTHETIC MANAGEMENT OF A PATIENT WITH CENTRAL AIRWAY COMPRESSION DUE TO POSTERIOR MEDIASTINAL MASS.

    PubMed

    Sulen, Nina; Petani, Barbara; Bacić, Ivan; Morović, Domagoj

    2016-03-01

    Patients with mediastinal masses present unique challenge to anesthesiologists. Patients with anterior mediastinal masses have well documented cases of respiratory or cardiovascular collapse during anesthesia and in postoperative period. Masses in the posterior mediastinum have been traditionally regarded to carry a significantly lower risk of anesthesia related complications but cases of near fatal cardiorespiratory complications have been reported. We describe anesthetic management of a patient with posterior mediastinal mass compressing the trachea and the left main bronchus presented for left thoracotomy and tumor excision. The patient experienced pain and cough, and exhibited positional dyspnea. Airway was successfully secured with awake nasotracheal intubation and placement of single lumen endobronchial tube. PMID:27276782

  8. Weak ENSO asymmetry due to weak nonlinear air-sea interaction in CMIP5 climate models

    NASA Astrophysics Data System (ADS)

    Sun, Yan; Wang, Fan; Sun, De-Zheng

    2016-03-01

    State-of-the-art climate models have long-standing intrinsic biases that limit their simulation and projection capabilities. Significantly weak ENSO asymmetry and weakly nonlinear air-sea interaction over the tropical Pacific was found in CMIP5 (Coupled Model Intercomparison Project, Phase 5) climate models compared with observation. The results suggest that a weak nonlinear air-sea interaction may play a role in the weak ENSO asymmetry. Moreover, a weak nonlinearity in air-sea interaction in the models may be associated with the biases in the mean climate—the cold biases in the equatorial central Pacific. The excessive cold tongue bias pushes the deep convection far west to the western Pacific warm pool region and suppresses its development in the central equatorial Pacific. The deep convection has difficulties in further moving to the eastern equatorial Pacific, especially during extreme El Ni˜no events, which confines the westerly wind anomaly to the western Pacific. This weakens the eastern Pacific El Ni˜no events, especially the extreme El Ni˜no events, and thus leads to the weakened ENSO asymmetry in climate models. An accurate mean state structure (especially a realistic cold tongue and deep convection) is critical to reproducing ENSO events in climate models. Our evaluation also revealed that ENSO statistics in CMIP5 climate models are slightly improved compared with those of CMIP3. The weak ENSO asymmetry in CMIP5 is closer to the observation. It is more evident in CMIP5 that strong ENSO activities are usually accompanied by strong ENSO asymmetry, and the diversity of ENSO amplitude is reduced.

  9. Model calculated global, regional and megacity premature mortality due to air pollution

    NASA Astrophysics Data System (ADS)

    Lelieveld, J.; Barlas, C.; Giannadaki, D.; Pozzer, A.

    2013-07-01

    Air pollution by fine particulate matter (PM2.5) and ozone (O3) has increased strongly with industrialization and urbanization. We estimate the premature mortality rates and the years of human life lost (YLL) caused by anthropogenic PM2.5 and O3 in 2005 for epidemiological regions defined by the World Health Organization (WHO). This is based upon high-resolution global model calculations that resolve urban and industrial regions in greater detail compared to previous work. Results indicate that 69% of the global population is exposed to an annual mean anthropogenic PM2.5 concentration of >10 μg m-3 (WHO guideline) and 33% to > 25 μg m-3 (EU directive). We applied an epidemiological health impact function and find that especially in large countries with extensive suburban and rural populations, air pollution-induced mortality rates have been underestimated given that previous studies largely focused on the urban environment. We calculate a global respiratory mortality of about 773 thousand/year (YLL ≈ 5.2 million/year), 186 thousand/year by lung cancer (YLL ≈ 1.7 million/year) and 2.0 million/year by cardiovascular disease (YLL ≈ 14.3 million/year). The global mean per capita mortality caused by air pollution is about 0.1% yr-1. The highest premature mortality rates are found in the Southeast Asia and Western Pacific regions (about 25% and 46% of the global rate, respectively) where more than a dozen of the most highly polluted megacities are located.

  10. Health impacts due to particulate air pollution in Volos City, Greece.

    PubMed

    Moustris, Konstantinos P; Proias, George T; Larissi, Ioanna K; Nastos, Panagiotis T; Koukouletsos, Konstantinos V; Paliatsos, Athanasios G

    2016-01-01

    There is great consensus among the scientific community that suspended particulate matter is considered as one of the most harmful pollutants, particularly the inhalable particulate matter with aerodynamic diameter less than 10 μm (PM10) causing respiratory health problems and heart disorders. Average daily concentrations exceeding established standard values appear, among other cases, to be the main cause of such episodes, especially during Saharan dust episodes, a natural phenomenon that degrades air quality in the urban area of Volos. In this study the AirQ2.2.3 model, developed by the World Health Organization (WHO) European Center for Environment and Health, was used to evaluate adverse health effects by PM10 pollution in the city of Volos during a 5-year period (2007-2011). Volos is a coastal medium size city in the Thessaly region. The city is located on the northern side of the Gulf of Pagassitikos, on the east coast of Central Greece. Air pollution data were obtained by a fully automated monitoring station, which was established by the Municipal Water Supply and Sewage Department in the Greater Area of Volos, located in the centre of the city. The results of the current study indicate that when the mean annual PM10 concentration exceeds the corresponding European Union (EU) threshold value, the number of hospital admissions for respiratory disease (HARD) is increased by 25% on average. There is also an estimated increase of about 2.5% in HARD compared to the expected annual HARD cases for Volos. Finally, a strong correlation was found between the number of days exceeding the EU daily threshold concentration ([PM10] ≥ 50 μg m(-3)) and the annual HARD cases. PMID:26421944

  11. Inhalation dose due to presence of 131I in air above septic tank system of an endocrinology hospital.

    PubMed

    Mietelski, J W; Grabowska, S; Nowak, T; Bogacz, J; Gaca, P; Bartyzel, M; Budzanowski, M

    2005-01-01

    We present here measurements of the 131I concentration for both: gaseous and aerosol fraction of 131I in the air above the septic tank containing wastes from medical application of this isotope. Aerosols were collected using air filters, whereas gaseous forms of iodine were trapped in KI impregnated charcoal double layer cartridge. Besides an active method (pumping of the air through system of filters) an attempt for using a passive method (charcoal traps) for monitoring of radio-iodine is described. For better characterisation of a site the external kerma was determined by means of G-M and TLD techniques as well as the activity kept in the septic tank was measured by gamma spectrometry. Results show that the activity of the aerosol fraction can be neglected compared to that of the gaseous fraction. He measured activity of air is low, on the level of 1 Bq m(-3), even during simulated failure of the ventilation system. Estimated inhalation dose for the serviceman of septic tanks is low ( approximately 10%) compared with external dose obtained by such person due to gamma radiation from the tank (on the level approximately 500 nSv h(-1)). Therefore, the concept of passive monitoring of the iodine in air was abandoned. Also estimated is the efficiency of 131I reduction by a charcoal filter of the ventilation system and 131I input to the environment by the ventilation chimney. PMID:15941814

  12. Modeling Study on Air Quality Improvement due to Mobile Source Emission control Plan in Seoul Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Kim, Y. J.; Sunwoo, Y.; Hwang, I.; Song, S.; Sin, J.; Kim, D.

    2015-12-01

    A very high population and corresponding high number of vehicles in the Seoul Metropolitan Area (SMA) are aggravating the air quality of this region. The Korean government continues to make concerted efforts to improve air quality. One of the major policies that the Ministry of Environment of Korea enforced is "The Special Act for Improvement of Air Quality in SMA" and "The 1st Air Quality Management Plan of SMA". Mobile Source emission controls are an important part of the policy. Thus, it is timely to evaluate the air quality improvement due to the controls. Therefore, we performed a quantitative analysis of the difference in air quality using the Community Multiscale Air Quality (CMAQ) model and December, 2011 was set as the target period to capture the impact of the above control plans. We considered four fuel-type vehicle emission scenarios and compared the air quality improvement differences between them. The scenarios are as follows: no-control, gasoline vehicle control only, diesel vehicle control only, and control of both; utilizing the revised mobile source emissions from the Clean Air Policy Support System (CAPSS), which is the national emission inventory reflecting current policy.In order to improve the accuracy of the modeling data, we developed new temporal allocation coefficients based on traffic volume observation data and spatially reallocated the mobile source emissions using vehicle flow survey data. Furthermore, we calculated the PM10 and PM2.5 emissions of gasoline vehicles which is omitted in CAPSS.The results of the air quality modeling shows that vehicle control plans for both gasoline and diesel lead to a decrease of 0.65ppb~8.75ppb and 0.02㎍/㎥~7.09㎍/㎥ in NO2 and PM10 monthly average concentrations, respectively. The large percentage decreases mainly appear near the center of the metropolis. However, the largest NO2 decrease percentages are found in the northeast region of Gyeonggi-do, which is the province that surrounds the

  13. Cumulative ventilation air drying potential as an indication of dry mass content in wastewater sludge in a thin-layer solar drying facility

    NASA Astrophysics Data System (ADS)

    Krawczyk, Piotr

    2013-12-01

    Controlling low-temperature drying facilities which utilise nonprepared air is quite difficult, due to very large variability of ventilation air parameters - both in daily and seasonal cycles. The paper defines the concept of cumulative drying potential of ventilation air and presents experimental evidence that there is a relation between this parameter and condition of the dried matter (sewage sludge). Knowledge on current dry mass content in the dried matter (sewage sludge) provides new possibilities for controlling such systems. Experimental data analysed in the paper was collected in early 2012 during operation of a test solar drying facility in a sewage treatment plant in Błonie near Warsaw, Poland.

  14. Measurement of Planet Masses with Transit Timing Variations Due to Synodic “Chopping” Effects

    NASA Astrophysics Data System (ADS)

    Deck, Katherine M.; Agol, Eric

    2015-04-01

    Gravitational interactions between planets in transiting exoplanetary systems lead to variations in the times of transit that are diagnostic of the planetary masses and the dynamical state of the system. Here we show that synodic “chopping” contributions to these transit timing variations (TTVs) can be used to uniquely measure the masses of planets without full dynamical analyses involving direct integration of the equations of motion. We present simple analytic formulae for the chopping signal, which are valid (generally \\lt 10% error) for modest eccentricities e≲ 0.1. Importantly, these formulae primarily depend on the mass of the perturbing planet, and therefore the chopping signal can be used to break the mass/free-eccentricity degeneracy, which can appear for systems near first-order mean motion resonances. Using a harmonic analysis, we apply these TTV formulae to a number of Kepler systems, which had been previously modeled with full dynamical analyses. We show that when chopping is measured, the masses of both planets can be determined uniquely, in agreement with previous results, but without the need for numerical orbit integrations. This demonstrates how mass measurements from TTVs may primarily arise from an observable chopping signal. The formula for chopping can also be used to predict the number of transits and timing precision required for future observations, such as those made by TESS or PLATO, in order to infer planetary masses through analysis of TTVs.

  15. Health effects of air pollution due to coal combustion in the Chestnut Ridge region of Pennsylvania

    SciTech Connect

    Batterman, S.; Golomb, D.

    1985-08-01

    This study used the seventeen monitor air quality network in the Chestnut Ridge region of Pennsylvania to evaluate the effect of pollutant trends and representations on measures of exposure. Data consisted of four and five years of SO/sub 2/ and TSP measurements, respectively, and were considered in deriving exposure models. A cross-sectional study of 4071 children aged 6 to 11 years of age was conducted in the spring of 1979. Standardized children's questionnaires were distributed to the parents and returned by the children to school, where spirometry was performed. The region was divided into low, moderate and high pollution areas on the basis of the 1974-1978, 3 h, 24 h, and annual averages for SO/sub 2/. After adjusting the respiratory symptom response outcomes and the pulmonary function levels for known predictors, no significant association was noted for level of SO/sub 2/. 65 refs., 16 figs., 19 tabs.

  16. Indoor air pollution due to tobacco smoke under real conditions. Preliminary results.

    PubMed

    Klus, H; Begutter, H; Nowak, A; Pinterits, G; Ultsch, I; Wihlidal, H

    1985-08-01

    A short review exploring the generation and composition of tobacco smoke is given. Experimental arrangements used to record sidestream smoke are critically discussed. Data from own experiments in a tobacco smoke polluted office room were presented and discussed. These data include nicotine, ammonia, formaldehyde, acetaldehyde, hydrogen cyanide, CO, NO and NO2. First results about the diameter of the particles in the smoke polluted room were also given. By the aid of the RINGOLD's equation the COHB content on basis of the CO-values of exhaled breath of active and passive smokers were determined. Data about the nitrosamine content in the air of the room during the smoke tests were also given and discussed. PMID:3836513

  17. Inert gas purgebox for Fourier transform ion cyclotron resonance mass spectrometry of air-sensitive solids

    NASA Astrophysics Data System (ADS)

    May, Michael A.; Marshall, Alan G.

    1994-03-01

    A sealed rigid ``purgebox'' makes it possible to load air- and/or moisture-sensitive solids into the solids probe inlet of a Fourier transform ion cyclotron resonance (FT/ICR) mass spectrometer. A pelletized sample is transferred (in a sealed canister) from a commercial drybox to a Lucite(R) purgebox. After the box is purged with inert gas, an attached glove manipulator is used to transfer the sample from the canister to the solids probe of the mass spectrometer. Once sealed inside the inlet, the sample is pre-evacuated and then passed into the high vacuum region of the instrument at ˜10-7 Torr. The purgebox is transparent, portable, and readily assembled/disassembled. Laser desorption FT/ICR mass spectra of the air- and moisture-sensitive solids, NbCl5. NbCl2(C5H5)2, and Zr(CH3)2(C5H5)2 are obtained without significant oxidation. The residual water vapor concentration inside the purgebox was measured as 100±20 ppm after a 90-min purge with dry nitrogen gas. High-resolution laser desorption/ionization mass spectrometry of air-sensitive solids becomes feasible with the present purgebox interface. With minor modification of the purgebox geometry, the present method could be adapted to any mass spectrometer equipped with a solid sample inlet.

  18. Study of the extensive air shower mass sensitive parameters in prototype of ALBORZ array

    NASA Astrophysics Data System (ADS)

    Rastegarzadeh, G.; Nemati, M.

    2015-03-01

    In this work we have used muon production depth distribution as well as the lateral distribution of the secondary particles of Extensive Air Showers (EAS) as two main parameters to infer the mass composition of primary cosmic rays. In order to achieve a realistic estimate of the mass composition, a sample of showers initiated by proton and iron particles as primaries have been simulated by CORSIKA code with zenith angle between 0° and 18° and discrete energies in a range between 1014 and 1016 eV for ALBORZ (1200 m a.s.l, Tehran, Iran) and KASKADE (110 m a.s.l, Karlsruhe, Germany) observation levels. Moreover lateral density distribution functions of energy for charged particles of air showers have been proposed for both proton and Iron primaries. We have indicated that among these two EAS parameters, lateral distribution of secondary particles provides better mass discrimination.

  19. Airborne mass spectrometers: four decades of atmospheric and space research at the Air Force research laboratory.

    PubMed

    Viggiano, A A; Hunton, D E

    1999-11-01

    Mass spectrometry is a versatile research tool that has proved to be extremely useful for exploring the fundamental nature of the earth's atmosphere and ionosphere and in helping to solve operational problems facing the Air Force and the Department of Defense. In the past 40 years, our research group at the Air Force Research Laboratory has flown quadrupole mass spectrometers of many designs on nearly 100 sounding rockets, nine satellites, three Space Shuttles and many missions of high-altitude research aircraft and balloons. We have also used our instruments in ground-based investigations of rocket and jet engine exhaust, combustion chemistry and microwave breakdown chemistry. This paper is a review of the instrumentation and techniques needed for space research, a summary of the results from many of the experiments, and an introduction to the broad field of atmospheric and space mass spectrometry in general. PMID:10548806

  20. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  1. Numerical prediction of rock mass damage due to accidental explosions in an underground ammunition storage chamber

    NASA Astrophysics Data System (ADS)

    Wu, Chengqing; Hao, Hong

    2006-03-01

    Accidental detonations in an underground ammunition storage chamber inside a rock mass may cause severe damage to the rock mass around the chamber, adjacent tunnels and chambers, ground surface, and in the worst case cause sympathetic detonation of explosives in adjacent storage chambers. To prevent such damage, underground ammunition storage chambers are often situated at minimum depth below the ground surface, and spaced at minimum distance from each other, so that damage, should it occur, is limited to the accidental chamber. Different codes and regulations for ammunition storage chambers specify minimum embedment depth and separation distance for underground ammunition storage chambers. They are usually given in terms of the rock mass properties and the weight of explosive stored in chambers. Some empirical formulae, usually based on the peak particle velocity of the stress wave or the maximum strain of the rock mass, are also available to estimate the damage zones in the rock mass from an explosion. All these empirical methods do not include the effects of explosion details, such as the loading density, chamber geometry and explosive distribution. In this paper, a previously calibrated numerical model is used to estimate the damage zones in a granite mass resulting from an accidental explosion in an underground ammunition storage chamber. Effects of various explosion conditions on rock mass damage are investigated. On the basis of the numerical results, some empirical formulae are derived to predict damage zones around the explosion chamber, as well as safe embedment depth of the storage chamber and safe separation distance between adjacent chambers. The numerical results are also compared with available empirical formulae and code specifications. It should be noted that the characteristics of stress wave propagation around an ammunition storage chamber has been published in a preceding paper (Int. J. Blast. Fragm. 5:57 90, 2001.

  2. Crustal uplift due to ice mass variability on Upernavik Isstrøm, west Greenland

    NASA Astrophysics Data System (ADS)

    Nielsen, Karina; Khan, Shfaqat Abbas; Korsgaard, Niels J.; Kjær, Kurt H.; Wahr, John; Bevis, Michael; Stearns, Leigh A.; Timm, Lars H.

    2012-11-01

    We estimate the mass loss rate of Upernavik Isstrøm (UI) using surface elevation changes between a SPOT 5 Digital Elevation Model (DEM) from 2008 and NASA's Airborne Topographic Mapper (ATM) data from 2010. To assess the validity of our mass loss estimate, we analyze GPS data between 2007 and 2011 from two continuous receivers, UPVK and SRMP which are established on bedrock and located ∼65 and ∼2 km from the front of UI, respectively. We construct along-track elevation changes on UI for several time intervals during 2005-2011, based on ATM, SPOT 5 and Ice, Cloud, and land Elevation Satellite (ICESat) data to assess temporal changes of UI. We estimate a mass loss rate of -6.7±4.2 Gt/yr, over an area of ∼1600 km2. The ice mass loss occurs primarily over the northern glacier of UI. This pattern is also observed ∼40 km upstream, where we observe glacier thinning at a rate of -1.6±0.3 m/yr across the northern portion of UI and -0.5±0.1 m/yr across the southern portion. GPS measurements suggest bedrock uplift rates of 7.6±0.6 mm/yr (UPVK) and 16.2±0.6 mm/yr (SRMP). The modeled ice mass loss of UI causes bedrock uplift rates of 1.3±0.6 mm/yr (UPVK) and 8.3±4.2 mm/yr (SRMP). Including additional contributions from ice mass changes outside UI and from Glacial Isostatic Adjustment (GIA), we obtain total modeled uplift rates of 4.7±0.6 mm/yr (UPVK) and 13.8±4.2 mm/yr (SRMP). The modeled uplift rates from our UI ice mass loss are substantially lower, indicating that additional mass loss is taking place outside of UI. We obtain a difference of 0.6 mm/yr between the modeled and observed relative uplift rates (SRMP relative to UPVK), suggesting that the mass loss of UI is well captured in the model. We observe elevation changes from -15 to -40 m/yr near the front during the period 2005-2011, indicating that UI undergoes large variations in thinning pattern over short time spans.

  3. Ozone-surface interactions: Investigations of mechanisms, kinetics, mass transport, and implications for indoor air quality

    SciTech Connect

    Morrison, Glenn C.

    1999-12-01

    {sup {minus}7}, 10{sup {minus}5}, and 10{sup {minus}5} respectively. To understand how internal surface area influences the equivalent reaction probability of whole carpet, a model of ozone diffusion into and reaction with internal carpet components was developed. This was then used to predict apparent reaction probabilities for carpet. He combines this with a modified model of turbulent mass transfer developed by Liu, et al. to predict deposition rates and indoor ozone concentrations. The model predicts that carpet should have an equivalent reaction probability of about 10{sup {minus}5}, matching laboratory measurements of the reaction probability. For both carpet and duct materials, surfaces become progressively quenched (aging), losing the ability to react or otherwise take up ozone. He evaluated the functional form of aging and find that the reaction probability follows a power function with respect to the cumulative uptake of ozone. To understand ozone aging of surfaces, he developed several mathematical descriptions of aging based on two different mechanisms. The observed functional form of aging is mimicked by a model which describes ozone diffusion with internal reaction in a solid. He shows that the fleecy nature of carpet materials in combination with the model of ozone diffusion below a fiber surface and internal reaction may explain the functional form and the magnitude of power function parameters observed due to ozone interactions with carpet. The ozone induced aldehyde emissions, measured from duct materials, were combined with an indoor air quality model to show that concentrations of aldehydes indoors may approach odorous levels. He shows that ducts are unlikely to be a significant sink for ozone due to the low reaction probability in combination with the short residence time of air in ducts.

  4. MHD simulations of boundary layer formation along the dayside Venus ionopause due to mass loading

    NASA Astrophysics Data System (ADS)

    McGary, J. E.; Pontius, D. H.

    1994-02-01

    A two-dimensional magnetohydrodynamic (MHD) simulation of mass-loaded solar wind flow around the dayside of Venus is presented. For conditions appropriate to a low-altitude ionopause the simulations show that mass loading from the pickup of oxygen ions produces a boundary layer of finite thickness along the ionopause. Within this layer the temperatures exhibit strong gradients normal to and away from the ionopause. Furthermore, there is a shear in the bulk flow velocity across the boundary layer, such that the (predominantly tangential) flow decreases in speed as the ionopause is approached and remains small along the ionopause, consistent with Pioneer Venus observations. The total mass density increases significantly as the flow approaches the ionopause, where the contribution of O(+) to the total number density is a few percent. Numerical simulations are carried out for various mass addition rates and demonstrate that the boundary layer develops when oxygen ion production exceeds approximately 2 x 105/cu m/s. For the upstream solar wind parameters and mass loading rates chosen for these simulations, the results are consistent with observations made on the dayside of Venus for average ionopause conditions near 300 km.

  5. Establishing Lagrangian Connections between Observations within Air Masses Crossing the Atlantic during the ICARTT Experiment

    NASA Technical Reports Server (NTRS)

    Methven, J.; Arnold, S. R.; Stohl, A.; Evans, M. J.; Avery, M.; Law, K.; Lewis, A. C.; Monks, P. S.; Parrish, D.; Reeves, C.; Schlager, H.; Atlas, E.; Blake, D.; Coe, H.; Cohen, R. C.; Crosier, J.; Flocke, F.; Holloway, J. S.; Hopkins, J. R.; Huber, G.; McQuaid, J.; Purvis, R.; Rappengluck, B.; Ryerson, T. B.; Sachse, G. W.

    2006-01-01

    The International Consortium for Atmospheric Research on Transport and Transformation (ICARTT)-Lagrangian experiment was conceived with an aim to quantify the effects of photochemistry and mixing on the transformation of air masses in the free troposphere away from emissions. To this end attempts were made to intercept and sample air masses several times during their journey across the North Atlantic using four aircraft based in New Hampshire (USA), Faial (Azores) and Creil (France). This article begins by describing forecasts using two Lagrangian models that were used to direct the aircraft into target air masses. A novel technique is then used to identify Lagrangian matches between flight segments. Two independent searches are conducted: for Lagrangian model matches and for pairs of whole air samples with matching hydrocarbon fingerprints. The information is filtered further by searching for matching hydrocarbon samples that are linked by matching trajectories. The quality of these coincident matches is assessed using temperature, humidity and tracer observations. The technique pulls out five clear Lagrangian cases covering a variety of situations and these are examined in detail. The matching trajectories and hydrocarbon fingerprints are shown and the downwind minus upwind differences in tracers are discussed.

  6. Characterising terrestrial influences on Antarctic air masses using Radon-222 measurements at King George Island

    NASA Astrophysics Data System (ADS)

    Chambers, S. D.; Hong, S.-B.; Williams, A. G.; Crawford, J.; Griffiths, A. D.; Park, S.-J.

    2014-09-01

    We report on one year of high-precision direct hourly radon observations at King Sejong Station (King George Island) beginning in February 2013. Findings are compared with historic and ongoing radon measurements from other Antarctic sites. Monthly median concentrations reduced from 72 mBq m-3 in late-summer to 44 mBq m-3 in late winter and early spring. Monthly 10th percentiles, ranging from 29 to 49 mBq m-3, were typical of oceanic baseline values. Diurnal cycles were rarely evident and local influences were minor, consistent with regional radon flux estimates one tenth of the global average for ice-free land. The predominant fetch region for terrestrially influenced air masses was South America (47-53° S), with minor influences also attributed to aged Australian air masses and local sources. Plume dilution factors of 2.8-4.0 were estimated for the most terrestrially influenced (South American) air masses, and a seasonal cycle in terrestrial influence on tropospheric air descending at the pole was identified and characterised.

  7. Characterising terrestrial influences on Antarctic air masses using radon-222 measurements at King George Island

    NASA Astrophysics Data System (ADS)

    Chambers, S. D.; Hong, S.-B.; Williams, A. G.; Crawford, J.; Griffiths, A. D.; Park, S.-J.

    2014-05-01

    We report on one year of high precision direct hourly radon observations at King Sejong Station (King George Island) beginning in February 2013. Findings are compared with historic and ongoing radon measurements from other Antarctic sites. Monthly median concentrations reduced from 72 mBq m-3 in late summer to 44 mBq m-3 in late-winter and early-spring. Monthly 10th percentiles, ranging from 29 to 49 mBq m-3, were typical of oceanic baseline values. Diurnal cycles were rarely evident and local influences were minor, consistent with regional radon flux estimates one tenth of the global average for ice-free land. The predominant fetch region for terrestrially influenced air masses was South America (47-53° S), with minor influences also attributed to aged Australian air masses and local sources. Plume dilution factors of 2.8-4.0 were estimated for the most terrestrially influenced (South American) air masses, and a seasonal cycle in terrestrial influence on tropospheric air descending at the pole was identified and characterised.

  8. Permanently reconfigured metamaterials due to terahertz induced mass transfer of gold.

    PubMed

    Strikwerda, Andrew C; Zalkovskij, Maksim; Iwaszczuk, Krzysztof; Lorenzen, Dennis Lund; Jepsen, Peter Uhd

    2015-05-01

    We present a new technique for permanent metamaterial reconfiguration via optically induced mass transfer of gold. This mass transfer, which can be explained by field-emission induced electromigration, causes a geometric change in the metamaterial sample. Since a metamaterial's electromagnetic response is dictated by its geometry, this structural change massively alters the metamaterial's behavior. We show this by optically forming a conducting pathway between two closely spaced dipole antennas, thereby changing the resonance frequency by a factor of two. After discussing the physics of the process, we conclude by presenting an optical fuse that can be used as a sacrificial element to protect sensitive components, demonstrating the applicability of optically induced mass transfer for device design. PMID:25969252

  9. Stable isotope composition of waters in the Great Basin, United States 1. Air-mass trajectories

    USGS Publications Warehouse

    Friedman, I.; Harris, J.M.; Smith, G.I.; Johnson, C.A.

    2002-01-01

    Isentropic trajectories, calculated using the NOAA/Climate Monitoring and Diagnostics Laboratory's isentropic transport model, were used to determine air-parcel origins and the influence of air mass trajectories on the isotopic composition of precipitation events that occurred between October 1991 and September 1993 at Cedar City, Utah, and Winnemucca, Nevada. Examination of trajectories that trace the position of air parcels backward in time for 10 days indicated five distinct regions of water vapor origin: (1) Gulf of Alaska and North Pacific, (2) central Pacific, (3) tropical Pacific, (4) Gulf of Mexico, and (5) continental land mass. Deuterium (??D) and oxygen-18 (??18O) analyses were made of precipitation representing 99% of all Cedar City events. Similar analyses were made on precipitation representing 66% of the precipitation falling at Winnemucca during the same period. The average isotopic composition of precipitation derived from each water vapor source was determined. More than half of the precipitation that fell at both sites during the study period originated in the tropical Pacific and traveled northeast to the Great Basin; only a small proportion traversed the Sierra Nevada. The isotopic composition of precipitation is determined by air-mass origin and its track to the collection station, mechanism of droplet formation, reequilibration within clouds, and evaporation during its passage from cloud to ground. The Rayleigh distillation model can explain the changes in isotopic composition of precipitation as an air mass is cooled pseudo-adiabatically during uplift. However, the complicated processes that take place in the rapidly convecting environment of cumulonimbus and other clouds that are common in the Great Basin, especially in summer, require modification of this model because raindrops that form in the lower portion of those clouds undergo isotopic change as they are elevated to upper levels of the clouds from where they eventually drop to the

  10. Stable isotope composition of waters in the Great Basin, United States 1. Air-mass trajectories

    NASA Astrophysics Data System (ADS)

    Friedman, Irving; Harris, Joyce M.; Smith, George I.; Johnson, Craig A.

    2002-10-01

    Isentropic trajectories, calculated using the NOAA/Climate Monitoring and Diagnostics Laboratory's isentropic transport model, were used to determine air-parcel origins and the influence of air mass trajectories on the isotopic composition of precipitation events that occurred between October 1991 and September 1993 at Cedar City, Utah, and Winnemucca, Nevada. Examination of trajectories that trace the position of air parcels backward in time for 10 days indicated five distinct regions of water vapor origin: (1) Gulf of Alaska and North Pacific, (2) central Pacific, (3) tropical Pacific, (4) Gulf of Mexico, and (5) continental land mass. Deuterium (δD) and oxygen-18 (δ18O) analyses were made of precipitation representing 99% of all Cedar City events. Similar analyses were made on precipitation representing 66% of the precipitation falling at Winnemucca during the same period. The average isotopic composition of precipitation derived from each water vapor source was determined. More than half of the precipitation that fell at both sites during the study period originated in the tropical Pacific and traveled northeast to the Great Basin; only a small proportion traversed the Sierra Nevada. The isotopic composition of precipitation is determined by air-mass origin and its track to the collection station, mechanism of droplet formation, reequilibration within clouds, and evaporation during its passage from cloud to ground. The Rayleigh distillation model can explain the changes in isotopic composition of precipitation as an air mass is cooled pseudo-adiabatically during uplift. However, the complicated processes that take place in the rapidly convecting environment of cumulonimbus and other clouds that are common in the Great Basin, especially in summer, require modification of this model because raindrops that form in the lower portion of those clouds undergo isotopic change as they are elevated to upper levels of the clouds from where they eventually drop to the

  11. DIRECT TRACE ANALYSIS OF VOLATILE ORGANIC COMPOUNDS IN AIR USING ION TRAP MASS SPECTROMETERS WITH FILTERED NOISE FIELDS

    EPA Science Inventory

    Two ion trap mass spectrometers and direct air sampling interfaces are being evaluated in the laboratory for monitoring toxic air pollutants in real time. he mass spectrometers are the large, laboratory-based Finnigan MAT ion trap (ITMS) and the compact, field-deployable Teledyne...

  12. Changes in tropospheric composition and air quality due to stratospheric ozone depletion and climate change.

    PubMed

    Wilson, S R; Solomon, K R; Tang, X

    2007-03-01

    It is well-understood that reductions in air quality play a significant role in both environmental and human health. Interactions between ozone depletion and global climate change will significantly alter atmospheric chemistry which, in turn, will cause changes in concentrations of natural and human-made gases and aerosols. Models predict that tropospheric ozone near the surface will increase globally by up to 10 to 30 ppbv (33 to 100% increase) during the period 2000 to 2100. With the increase in the amount of the stratospheric ozone, increased transport from the stratosphere to the troposphere will result in different responses in polluted and unpolluted areas. In contrast, global changes in tropospheric hydroxyl radical (OH) are not predicted to be large, except where influenced by the presence of oxidizable organic matter, such as from large-scale forest fires. Recent measurements in a relatively clean location over 5 years showed that OH concentrations can be predicted by the intensity of solar ultraviolet radiation. If this relationship is confirmed by further observations, this approach could be used to simplify assessments of air quality. Analysis of surface-level ozone observations in Antarctica suggests that there has been a significant change in the chemistry of the boundary layer of the atmosphere in this region as a result of stratospheric ozone depletion. The oxidation potential of the Antarctic boundary layer is estimated to be greater now than before the development of the ozone hole. Recent modeling studies have suggested that iodine and iodine-containing substances from natural sources, such as the ocean, may increase stratospheric ozone depletion significantly in polar regions during spring. Given the uncertainty of the fate of iodine in the stratosphere, the results may also be relevant for stratospheric ozone depletion and measurements of the influence of these substances on ozone depletion should be considered in the future. In agreement with

  13. Loss of BMPR2 leads to high bone mass due to increased osteoblast activity

    PubMed Central

    Lowery, Jonathan W.; Intini, Giuseppe; Gamer, Laura; Lotinun, Sutada; Salazar, Valerie S.; Ote, Satoshi; Cox, Karen; Baron, Roland; Rosen, Vicki

    2015-01-01

    ABSTRACT Imbalances in the ratio of bone morphogenetic protein (BMP) versus activin and TGFβ signaling are increasingly associated with human diseases yet the mechanisms mediating this relationship remain unclear. The type 2 receptors ACVR2A and ACVR2B bind BMPs and activins but the type 2 receptor BMPR2 only binds BMPs, suggesting that type 2 receptor utilization might play a role in mediating the interaction of these pathways. We tested this hypothesis in the mouse skeleton, where bone mass is reciprocally regulated by BMP signaling and activin and TGFβ signaling. We found that deleting Bmpr2 in mouse skeletal progenitor cells (Bmpr2-cKO mice) selectively impaired activin signaling but had no effect on BMP signaling, resulting in an increased bone formation rate and high bone mass. Additionally, activin sequestration had no effect on bone mass in Bmpr2-cKO mice but increased bone mass in wild-type mice. Our findings suggest a novel model whereby BMPR2 availability alleviates receptor-level competition between BMPs and activins and where utilization of ACVR2A and ACVR2B by BMPs comes at the expense of activins. As BMP and activin pathway modulation are of current therapeutic interest, our findings provide important mechanistic insight into the relationship between these pathways in human health. PMID:25663702

  14. Measurement of HO{sub x}{center_dot} production rate due to radon decay in air

    SciTech Connect

    Ding, Huiling

    1993-08-01

    Radon in indoor air may cause the exposure of the public to excessive radioactivity. Radiolysis of water vapor in indoor air due to radon decay could produce ({center_dot}OH and HO{sub 2} {center_dot}) that may convert atmospheric constituents to compounds of lower vapor pressure. These lower vapor pressure compounds might then nucleate to form new particles in the indoor atmosphere. Chemical amplification was used to determine HO{sub x}{center_dot} production rate in indoor air caused by radon decay. Average HO{sub x}{center_dot} production rate was found to be (4.31{plus_minus}0.07) {times} 10{sup 5} HO{sub x}{center_dot} per Rn decay per second (Bq) 3.4 to 55.0% at 22C. This work provided G{sub (HO{sub x}{center_dot})}-value, 7.86{plus_minus}0.13 No./100 eV in air by directly measuring [HO{sub x}{center_dot}] formed from the radiolysis procedure. This G value implies that HO{sub x}{center_dot} produced by radon decay in air might be formed by multiple processes and may be result of positive ion-molecule reactions, primary radiolysis, and radical reactions. There is no obvious relation between HO{sub x}{center_dot} production rate and relative humidity. A laser-induced fluorescence (LIF) system has been used for {center_dot}OH production rate measurement; it consists of an excimer laser, a dye laser, a frequency doubler, a gaseous fluorescence chamber, and other optical and electronic parts. This system needs to be improved to eliminate the interferences of light scattering and artificial {center_dot}OH produced from the photolysis of O{sub 3}/H{sub 2}O.

  15. Crustal uplift due to ice mass variability on Upernavik Isstroem, west Greenland

    NASA Astrophysics Data System (ADS)

    Nielsen, K.; Khan, S. A.; Korsgaard, N.; Kjaer, K. H.; Wahr, J. M.; Bevis, M. G.; Stearns, L. A.; Timm, L. H.

    2012-12-01

    We estimate the mass loss rate of Upernavik Isstroem using surface elevation changes between a SPOT 5 Digital Elevation Model (DEM) from 2008 and NASA's Airborne Topographic Mapper (ATM) data from 2010. To assess the validity of our mass loss estimate, we analyze GPS data between 2007 and 2011 from two continuous receivers, UPVK and SRMP which are established on bedrock and located ~65 and ~2 km from the front of UI, respectively. We construct along-track elevation changes on UI for several time intervals during 2005 - 2011, based on ATM, SPOT 5 and Ice, Cloud, and land Elevation Satellite (ICESat) data to assess temporal changes of UI. We estimate a mass loss rate of -6.7 +/- 4.2 Gt/yr, over an area of ~1600 km^2. The ice mass loss occurs primarily over the northern glacier of UI. This pattern is also observed ~40 km upstream, where we observe glacier thinning at a rate of -1.6 +/- 0.3 m/yr across the northern portion of UI and -0.5 +/-0.1 m/yr across the southern portion. We obtain a difference of 0.6 mm/yr between the modeled and observed relative uplift rates at SRMP relative to UPVK, suggesting that the mass loss of UI is well captured in the model. We observe elevation changes from -15 to -40 m/yr near the front during the period 2005 - 2011, indicating that UI undergoes large variations in thinning pattern over short time spans.

  16. Dose perturbations due to contrast medium and air in MammoSite registered treatment: An experimental and Monte Carlo study

    SciTech Connect

    Cheng, C.-W.; Mitra, R.; Allen Li, X.; Das, Indra J.

    2005-07-15

    In the management of early breast cancer, a partial breast irradiation technique called MammoSite registered (Proxima Therapeutic Inc., Alpharetta, GA) has been advocated in recent years. In MammoSite, a balloon implanted at the surgical cavity during tumor excision is filled with a radio-opaque solution, and radiation is delivered via a high dose rate brachytherapy source situated at the center of the balloon. Frequently air may be introduced during placement of the balloon and/or injection of the contrast solution into the balloon. The purpose of this work is to quantify as well as to understand dose perturbations due to the presence of a high-Z contrast medium and/or an air bubble with measurements and Monte Carlo calculations. In addition, the measured dose distribution is compared with that obtained from a commercial treatment planning system (Nucletron PLATO system). For a balloon diameter of 42 mm, the dose variation as a function of distance from the balloon surface is measured for various concentrations of a radio-opaque solution (in the range 5%-25% by volume) with a small volume parallel plate ion chamber and a micro-diode detector placed perpendicular to the balloon axis. Monte Carlo simulations are performed to provide a basic understanding of the interaction mechanism and the magnitude of dose perturbation at the interface near balloon surface. Our results show that the radio-opaque concentration produces dose perturbation up to 6%. The dose perturbation occurs mostly within the distances <1 mm from the balloon surface. The Plato system that does not include heterogeneity correction may be sufficient for dose planning at distances {>=}10 mm from the balloon surface for the iodine concentrations used in the MammoSite procedures. The dose enhancement effect near the balloon surface (<1 mm) due to the higher iodine concentration is not correctly predicted by the Plato system. The dose near the balloon surface may be increased by 0.5% per cm{sup 3} of air

  17. Study of single and combined mass-sensitive observables of cosmic ray induced extensive air showers

    NASA Astrophysics Data System (ADS)

    Rastegarzadeh, G.; Nemati, M.

    2016-03-01

    In this study, combinations of the global arrival time, (Δτ_{global}), pseudorapidity, and lateral density distribution (ρ_{μ}) of muons, which are three mass-sensitive observables of cosmic ray induced extensive air showers, have been used as new parameters to study the primary mass discrimination around the knee energies (100 TeV-10 PeV). This is a simulation-based study and the simulations have been performed for the KASCADE array at Karlsruhe and the Alborz-I array at Tehran to study the effect of the altitude on the quality of the primary mass discrimination. The merit factors of the single and combined three mass-sensitive observables have been calculated to compare the discrimination power of combined and single observables. We have used the CORSIKA 7.4 code to simulate the extensive air showers (EASs) sample sets. Considering all aspects of our study, it is found that the ratio of the global time to the lateral density distribution of the muons gives better results than other ratios; also in the case of single observables, the muon density gives better results compared with the other observables. Also it is shown that below 1 PeV primary energies, the ratio of the muon global time to the muon density (Δτ_{global}/ρ_{μ}) results in a better mass discrimination relative to the muon density only.

  18. On the gravitational potential and field anomalies due to thin mass layers

    NASA Technical Reports Server (NTRS)

    Ockendon, J. R.; Turcotte, D. L.

    1977-01-01

    The gravitational potential and field anomalies for thin mass layers are derived using the technique of matched asymptotic expansions. An inner solution is obtained using an expansion in powers of the thickness and it is shown that the outer solution is given by a surface distribution of mass sources and dipoles. Coefficients are evaluated by matching the inner expansion of the outer solution with the outer expansion of the inner solution. The leading term in the inner expansion for the normal gravitational field gives the Bouguer formula. The leading term in the expansion for the gravitational potential gives an expression for the perturbation to the geoid. The predictions given by this term are compared with measurements by satellite altimetry. The second-order terms in the expansion for the gravitational field are required to predict the gravity anomaly at a continental margin. The results are compared with observations.

  19. Bias in GRACE estimates of ice mass change due to accompanying sea-level change

    NASA Astrophysics Data System (ADS)

    Sterenborg, M. G.; Morrow, E.; Mitrovica, J. X.

    2013-04-01

    Observations of spatio-temporal variations in the geopotential using the GRACE satellites have been used to estimate recent mass fluxes from polar ice sheets and glaciers. However, these estimates have not considered the potential bias associated with the migration of water that accompanies the ice melt. This migration is driven by the diminished gravitational attraction of the melting ice reservoir, and this migration, as well as the crustal loading it induces, will contribute to the observed geopotential anomaly. The extent to which this contribution contaminates the ice mass flux estimates depends on how far the smoothing filters applied to the GRACE data extend beyond the ice margins into the ocean. Using the Antarctic Peninsula as a case study, we estimate the magnitude of this bias for a range of melt areas and Gaussian smoothing filter radii. We conclude that GRACE estimates of ice mass loss over the Antarctic Peninsula are systematically overestimating the loss by up to 10 % for filter radii of less than 500 km.

  20. Enhancement of acidic gases in biomass burning impacted air masses over Canada

    NASA Technical Reports Server (NTRS)

    Lefer, B. L.; Talbot, R. W.; Harriss, R. C.; Bradshaw, J. D.; Sandholm, S. T.; Olson, J. O.; Sachse, G. W.; Collins, J.; Shipham, M. A.; Blake, D. R.

    1994-01-01

    Biomass-burning impacted air masses sampled over central and eastern Canada during the summer of 1990 as part of ABLE 3B contained enhanced mixing ratios of gaseous HNO3, HCOOH, CH3COOH, and what appears to be (COOH)2. These aircraft-based samples were collected from a variety of fresh burning plumes and more aged haze layers from different source regions. Values of the enhancement factor, delta X/delta CO, where X represents an acidic gas, for combustion-impacted air masses sampled both near and farther away from the fires, were relatively uniform. However, comparison of carboxylic acid emission ratios measured in laboratory fires to field plume enhancement factors indicates significant in-plume production of HCOOH. Biomass-burning appears to be an important source of HNO3, HCOOH, and CH3COOH to the troposphere over subarctic Canada.

  1. Influence of the ozone profile above Madrid (Spain) on Brewer estimation of ozone air mass factor

    NASA Astrophysics Data System (ADS)

    Antón, M.; López, M.; Costa, M. J.; Serrano, A.; Bortoli, D.; Bañón, M.; Vilaplana, J. M.; Silva, A. M.

    2009-08-01

    The methodology used by Brewer spectroradiometers to estimate the ozone column is based on differential absorption spectroscopy. This methodology employs the ozone air mass factor (AMF) to derive the total ozone column from the slant path ozone amount. For the calculating the ozone AMF, the Brewer algorithm assumes that the ozone layer is located at a fixed height of 22 km. However, for a real specific site the ozone presents a certain profile, which varies spatially and temporally depending on the latitude, altitude and dynamical conditions of the atmosphere above the site of measurements. In this sense, this work address the reliability of the mentioned assumption and analyses the influence of the ozone profiles measured above Madrid (Spain) in the ozone AMF calculations. The approximated ozone AMF used by the Brewer algorithm is compared with simulations obtained using the libRadtran radiative transfer model code. The results show an excellent agreement between the simulated and the approximated AMF values for solar zenith angle lower than 75°. In addition, the relative differences remain lower than 2% at 85°. These good results are mainly due to the fact that the altitude of the ozone layer assumed constant by the Brewer algorithm for all latitudes notably can be considered representative of the real profile of ozone above Madrid (average value of 21.7±1.8 km). The operational ozone AMF calculations for Brewer instruments are limited, in general, to SZA below 80°. Extending the usable SZA range is especially relevant for Brewer instruments located at high mid-latitudes.

  2. Estimation of whole lemon mass transfer parameters during hot air drying using different modelling methods

    NASA Astrophysics Data System (ADS)

    Torki-Harchegani, Mehdi; Ghanbarian, Davoud; Sadeghi, Morteza

    2015-08-01

    To design new dryers or improve existing drying equipments, accurate values of mass transfer parameters is of great importance. In this study, an experimental and theoretical investigation of drying whole lemons was carried out. The whole lemons were dried in a convective hot air dryer at different air temperatures (50, 60 and 75 °C) and a constant air velocity (1 m s-1). In theoretical consideration, three moisture transfer models including Dincer and Dost model, Bi- G correlation approach and conventional solution of Fick's second law of diffusion were used to determine moisture transfer parameters and predict dimensionless moisture content curves. The predicted results were then compared with the experimental data and the higher degree of prediction accuracy was achieved by the Dincer and Dost model.

  3. Spatial variability of hailfalls in France: an analysis of air mass retro-trajectories

    NASA Astrophysics Data System (ADS)

    Hermida, Lucía; Merino, Andrés; Sánchez, José Luis; Berthet, Claude; Dessens, Jean; López, Laura; Fernández-González, Sergio; Gascón, Estíbaliz; García-Ortega, Eduardo

    2014-05-01

    Hail is the main meteorological risk in south-west France, with the strongest hailfalls being concentrated in just a few days. Specifically, this phenomenon occurs most often and with the greatest severity in the Midi-Pyrénées area. Previous studies have revealed the high spatial variability of hailfall in this part of France, even leading to different characteristics being recorded on hailpads that were relatively close together. For this reason, an analysis of the air mass trajectories was carried out at ground level and at altitude, which subsequently led to the formation of the hail recorded by these hailpads. It is already known that in the study zone, the trajectories of the storms usually stretch for long distances and are oriented towards the east, leading to hailstones with diameters in excess of 3 cm, and without any change in direction above 3 km. We analysed different days with hail precipitation where there was at least one stone with a diameter of 3 cm or larger. Using the simulations from these days, an analysis of the backward trajectories of the air masses was carried out. We used the HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) to determine the origin of the air masses, and tracked them toward each of the hailpads that were hit during the day studied. The height of the final points was the height of the impacted hailpads. Similarly, the backward trajectories for different heights were also established. Finally, the results show how storms that affect neighbouring hailpads come from very different air masses; and provide a deeper understanding of the high variability that affects the characteristics of hailfalls. Acknowledgements The authors would like to thank the Regional Government of Castile-León for its financial support through the project LE220A11-2. This study was supported by the following grants: GRANIMETRO (CGL2010-15930); MICROMETEO (IPT-310000-2010-22).

  4. Variation of annual effective dose due to radon level in indoor air in Marwar region of Rajasthan, India

    NASA Astrophysics Data System (ADS)

    Rani, Asha; Mittal, Sudhir; Mehra, Rohit

    2015-08-01

    In the present work, indoor radon and thoron measurements have been carried out from different locations of Jodhpur and Nagaur districts of Northern Rajasthan, India using RAD7, a solid state alpha detector. The radon and thoron concentration in indoor air varies from 8.75 to 61.25 Bq m-3 and 32.7 to 147.2 Bq m-3 with the mean value of 32 and 73 Bq m-3 respectively. The observed indoor radon concentration values are well below the action level recommended by International Commission on Radiological Protection (200-300 Bq m-3) and Environmental Protection Agency (148 Bq m-3). The survey reveals that the thoron concentration values in the indoor air are well within the International Commission on Radiological Protection (2005). The calculated total annual effective dose due to radon level in indoor air varies from 0.22 to 1.54 mSv y-1 with the mean value of 0.81 mSv y-1 which is less than even the lower limit of action level 3-10 mSv y-1 recommended by International Commission on Radiological Protection (2005).

  5. Variation of annual effective dose due to radon level in indoor air in Marwar region of Rajasthan, India

    SciTech Connect

    Rani, Asha; Mittal, Sudhir; Mehra, Rohit

    2015-08-28

    In the present work, indoor radon and thoron measurements have been carried out from different locations of Jodhpur and Nagaur districts of Northern Rajasthan, India using RAD7, a solid state alpha detector. The radon and thoron concentration in indoor air varies from 8.75 to 61.25 Bq m{sup −3} and 32.7 to 147.2 Bq m{sup −3} with the mean value of 32 and 73 Bq m{sup −3} respectively. The observed indoor radon concentration values are well below the action level recommended by International Commission on Radiological Protection (200-300 Bq m{sup −3}) and Environmental Protection Agency (148 Bq m{sup −3}). The survey reveals that the thoron concentration values in the indoor air are well within the International Commission on Radiological Protection (2005). The calculated total annual effective dose due to radon level in indoor air varies from 0.22 to 1.54 mSv y{sup −1} with the mean value of 0.81 mSv y{sup −1} which is less than even the lower limit of action level 3-10 mSv y{sup −1} recommended by International Commission on Radiological Protection (2005)

  6. Mass transfer characteristics of bisporus mushroom ( Agaricus bisporus) slices during convective hot air drying

    NASA Astrophysics Data System (ADS)

    Ghanbarian, Davoud; Baraani Dastjerdi, Mojtaba; Torki-Harchegani, Mehdi

    2016-05-01

    An accurate understanding of moisture transfer parameters, including moisture diffusivity and moisture transfer coefficient, is essential for efficient mass transfer analysis and to design new dryers or improve existing drying equipments. The main objective of the present study was to carry out an experimental and theoretical investigation of mushroom slices drying and determine the mass transfer characteristics of the samples dried under different conditions. The mushroom slices with two thicknesses of 3 and 5 mm were dried at air temperatures of 40, 50 and 60 °C and air flow rates of 1 and 1.5 m s-1. The Dincer and Dost model was used to determine the moisture transfer parameters and predict the drying curves. It was observed that the entire drying process took place in the falling drying rate period. The obtained lag factor and Biot number indicated that the moisture transfer in the samples was controlled by both internal and external resistance. The effective moisture diffusivity and the moisture transfer coefficient increased with increasing air temperature, air flow rate and samples thickness and varied in the ranges of 6.5175 × 10-10 to 1.6726 × 10-9 m2 s-1 and 2.7715 × 10-7 to 3.5512 × 10-7 m s-1, respectively. The validation of the Dincer and Dost model indicated a good capability of the model to describe the drying curves of the mushroom slices.

  7. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways

    NASA Astrophysics Data System (ADS)

    Liu, D. X.; Liu, Z. C.; Chen, C.; Yang, A. J.; Li, D.; Rong, M. Z.; Chen, H. L.; Kong, M. G.

    2016-04-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H+, nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2‑ and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios.

  8. Analysis of air mass trajectories in the northern plateau of the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Pérez, Isidro A.; Sánchez, M. Luisa; García, M. Ángeles; Pardo, Nuria

    2015-11-01

    Air masses reaching the Iberian Peninsula, which is located between two continents and two seas, have been classified. 24-h backward air trajectories were calculated each hour for three years using the METEX model at a site in the centre of the northern plateau of the Iberian Peninsula where the air flow has scarcely been investigated to date. Rather than the usual Euclidean geometry, spherical trigonometry, together with the kernel regression method, was considered to calculate trajectory distances to the site. Numerical indicators allow for an accurate description of the results. Ranges surrounding the site from E to S evidenced a restriction in the movement of the arriving flow. However, the range to the N showed only a slight effect. A noticeable seasonal contrast was observed between winter, whose distances were the greatest, and summer, which displayed the shortest distances. Trajectory clusters, initially not considered in the METEX model, were obtained with different metrics to determine the air mass pathways reaching the site. Five clusters of trajectories were selected so as to easily explain the directions and distances covered. Regional and long range transport were observed in clusters from the NE, NW and SW. The NE cluster presented an orographic deviation and local processes were limited to the SE cluster. Finally, seasonal analysis revealed singular behaviour during autumn, when local processes centred on the N-S direction.

  9. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways.

    PubMed

    Liu, D X; Liu, Z C; Chen, C; Yang, A J; Li, D; Rong, M Z; Chen, H L; Kong, M G

    2016-01-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H(+), nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2(-) and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios. PMID:27033381

  10. Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocity

    NASA Technical Reports Server (NTRS)

    Bugbee, B.; Monje, O.; Tanner, B.

    1996-01-01

    Here we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature.

  11. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways

    PubMed Central

    Liu, D. X.; Liu, Z. C.; Chen, C.; Yang, A. J.; Li, D.; Rong, M. Z.; Chen, H. L.; Kong, M. G.

    2016-01-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H+, nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2− and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios. PMID:27033381

  12. Anesthetic management of superior vena cava syndrome due to anterior mediastinal mass

    PubMed Central

    Chaudhary, Kapil; Gupta, Anshu; Wadhawan, Sonia; Jain, Divya; Bhadoria, Poonam

    2012-01-01

    Anesthetic management of superior vena cava syndrome carries a possible risk of life-threatening complications such as cardiovascular collapse and complete airway obstruction during anesthesia. Superior vena cava syndrome results from the enlargement of a mediastinal mass and consequent compression of mediastinal structures resulting in impaired blood flow from superior vena cava to the right atrium and venous congestion of face and upper extremity. We report the successful anesthetic management of a 42-year-old man with superior vena cava syndrome posted for cervical lymph node biopsy. PMID:22557753

  13. Estimating How Often Mass Extinctions Due to Impacts Occur on the Earth

    NASA Technical Reports Server (NTRS)

    Buratti, Bonnie J.

    2013-01-01

    This hands-on, inquiry based activity has been taught at JPL's summer workshop "Teachers Touch the Sky" for the past two decades. Students act as mini-investigators as they gather and analyze data to estimate how often an impact large enough to cause a mass extinction occurs on the Earth. Large craters are counted on the Moon, and this number is extrapolated to the size of the Earth. Given the age of the Solar System, the students can then estimate how often large impacts occur on the Earth. This activity is based on an idea by Dr. David Morrison, NASA Ames Research Center.

  14. A Rare Case of an Early Postoperative Obstructive Ileus in a Young Female Patient due to a Residual Trichobezoar Mass

    PubMed Central

    Christopoulos, P.; Ross-Thriepland, S.; McCarthy, H.; Day, C. S.; Sasi, W.

    2016-01-01

    Trichobezoar is a rare cause of small bowel obstruction, whereby a mass forms most commonly in the stomach and duodenum of young females, from ingestion of hair, a condition known as trichophagia. We present a case of recurrent small bowel obstruction due to a residual hair mass that was removed surgically in a young female patient who had a laparotomy and gastrotomy for removal of a large gastric trichobezoar just two weeks prior to the current admission. This case illustrates the importance of a thorough inspection of the whole bowel to ensure that no residual bezoars remain after surgery. PMID:27148464

  15. Mass extinction of the marine biota at the Ordovician-Silurian transition due to environmental changes

    NASA Astrophysics Data System (ADS)

    Barash, M. S.

    2014-11-01

    The terminal Ordovician was marked by one of five great mass extinction events of the Phanerozoic (445.6-443.0 Ma ago), when up to 86% of the marine species became extinct. The rapid onset of the continental glaciation on Gondwana determined by its position in the South Pole area; the cooling; the hydrodynamic changes through the entire water column in the World Ocean; and the corresponding sea level fall, which was responsible for the reduction of shelf areas and shallow-water basins, i.e., the main ecological niche of the Ordovician marine biota, were main prerequisites of the stress conditions. Similar to other mass extinction events, these processes were accompanied by volcanism, impact events, a corresponding reduction of the photosynthesis and bioproductivity, the destruction of food chains, and anoxia. The appearance and development of terrestrial plants and microphytoplankton, which consumed atmospheric carbon dioxide, thus, diminishing the greenhouse effect and promoting the transition of the climatic system to the glacial mode, played a unique role in that period.

  16. Time-Variable Gravity Signal Due to Extratropic Pacific Water Mass Redistribution

    NASA Technical Reports Server (NTRS)

    Chao, Benjamin F.; Au, A. Y.; Cox, C. M.

    2002-01-01

    Cox and Chao [2002] reported the detection of a large anomaly in the form of a positive "jump" in the time series of Earth's lowest-degree gravity harmonic J2, or the dynamic oblateness, during 1998. This prompted us to examine the mass redistribution in the global oceans. We report here a seesaw of the sea-surface height (SSH) in the extratropic north + south Pacific basins -- the leading (nonseasonal) EOF/PC mode in SSH derived from the 10-year TOPEX/Poseidon altimetry data in the extratropic Pacific region. The mode underwent a step-like jump with time evolution that match remarkably well with the observed J2 anomaly. However, the magnitude is several times too small to explain the observed J2, even if assuming the SSH jump was all mass-induced (as opposed to any steric effect which causes no time-variable gravity signal). If one accepts the notion that this extratropic Pacific seesaw is part of the geophysical process that produced the observed 1998 J2 anomaly, then this finding suggests strong geophysical connection of the interannual-to-decadal variation of J2 with the Pacific Decadal Oscillation (PDO), as the time series of the above EOF/PC mode is actually a formally defined PDO Index series.

  17. Performance of tuned mass damper against structural collapse due to near fault earthquakes

    NASA Astrophysics Data System (ADS)

    Domizio, Martín; Ambrosini, Daniel; Curadelli, Oscar

    2015-02-01

    Tuned mass dampers (TMD) are devices capable of reducing structural vibration by means of transferring energy from the protected structure to the control device. This vibration control strategy has relatively recent use in civil structures, and was proven effective against wind and far-fault earthquakes. In this paper, the effect of near-fault seismic records on structures with TMDs is studied. This type of seismic records has a short significant duration, with few pulses of high amplitude and low frequency. These characteristics raise a question about TMD performance against this type of earthquakes because the device has a very limited time to transfer the energy from the main structure. In this paper, the efficiency of TMD in preventing the collapse of a structure subjected to a series of near-fault records is analyzed. The structure used is a 4-story steel frame on which TMDs with different values of mass are incorporated. From a series of nonlinear dynamic analyses, where the scale of seismic records is modified, the minimum amplitude of each record that produces the structural collapse is found. By comparing the results of the structure with and without the addition of the control device, conclusions about its performance and capability in the prevention of collapse are established.

  18. LOW-MASS SUPPRESSION OF THE SATELLITE LUMINOSITY FUNCTION DUE TO THE SUPERSONIC BARYON-COLD-DARK-MATTER RELATIVE VELOCITY

    SciTech Connect

    Bovy, Jo; Dvorkin, Cora

    2013-05-01

    We study the effect of the supersonic baryon-cold-dark-matter (CDM) flow, which has recently been shown to have a large effect on structure formation during the dark ages 10 {approx}< z {approx}< 1000, on the abundance of luminous, low-mass satellite galaxies around galaxies like the Milky Way. As the supersonic baryon-CDM flow significantly suppresses both the number of halos formed and the amount of baryons accreted onto such halos of masses 10{sup 6} < M{sub halo}/M{sub Sun} < 10{sup 8} at z {approx}> 10, a large effect results on the stellar luminosity function before reionization. As halos of these masses are believed to have very little star formation after reionization due to the effects of photoheating by the ultraviolet background, this effect persists to the present day. We calculate that the number of low-mass 10{sup 6} < M{sub halo}/M{sub Sun} < 5 Multiplication-Sign 10{sup 7} halos that host luminous satellite galaxies today is typically suppressed by 50%, with values ranging up to 90% in regions where the initial supersonic velocity is high. We show that this previously ignored cosmological effect resolves some of the tension between the observed and predicted number of low-mass satellites in the Milky Way, reducing the need for other mass-dependent star-formation suppression before reionization.

  19. Influence of drying air parameters on mass transfer characteristics of apple slices

    NASA Astrophysics Data System (ADS)

    Beigi, Mohsen

    2015-12-01

    To efficiently design both new drying process and equipment and/or to improve the existing systems, accurate values of mass transfer characteristics are necessary. The present study aimed to investigate the influence of drying air parameters (i.e. temperature, velocity and relative humidity) on effective diffusivity and convective mass transfer coefficient of apple slices. The Dincer and Dost model was used to determine the mass transfer characteristics. The obtained Biot number indicated that the moisture transfer in the apple slices was controlled by both internal and external resistance. The effective diffusivity and mass transfer coefficient values obtained to be in the ranges of 7.13 × 10-11-7.66 × 10-10 and 1.46 × 10-7-3.39 × 10-7 m s-1, respectively and the both of them increased with increasing drying air temperature and velocity, and decreasing relative humidity. The validation of the model showed that the model predicted the experimental drying curves of the samples with a good accuracy.

  20. Small-size mass spectrometer for determining gases and volatile compounds in air during breathing

    NASA Astrophysics Data System (ADS)

    Kogan, V. T.; Kozlenok, A. V.; Chichagov, Yu. V.; Antonov, A. S.; Lebedev, D. S.; Bogdanov, A. A.; Moroshkin, V. S.; Berezina, A. V.; Viktorova-Leclerc, O. S.; Vlasov, S. A.; Tubol'tsev, Yu. V.

    2015-10-01

    We describe an automated mass spectrometer for diagnostics of deceases from the composition of exhaled air. It includes a capillary system, which performs a rapid direct feeding of the sample to the instrument without changing substantially its composition and serves for studying the dynamics of variation of the ratio between various components of exhaled air. The membrane system for introducing the sample is intended for determining low concentrations of volatile organic compounds which are biomarkers of pathologies. It is characterized by selective transmittance and ensures the detection limits of target compounds at the parts per million-parts per billion (ppm-ppb) level. A static mass analyzer operating on permanent magnets possesses advantages important for mobile devices as compared to its dynamic analogs: it is more reliable in operation, has a larger dynamic range, and can be used for determining the concentration of components in the mixture one-by-one or simultaneously. The curvilinear output boundary of the magnetic lens of the mass analyzer makes it possible to reduce its weight and size by 2.5 times without deteriorating the mass resolution. We report on the results of testing of the instrument and consider the possibility of its application for early detection of deceases of respiratory and blood circulation system, gastrointestinal tract, and endocrine system.

  1. Uncertainty in alpine snow mass balance simulations due to snow model parameterisation and windflow representation

    NASA Astrophysics Data System (ADS)

    Musselman, K. N.; Pomeroy, J. W.; Essery, R.; Leroux, N.

    2013-12-01

    Despite advances in alpine snow modelling there remain two fundamental areas of divergent scientific thought in estimating alpine snow mass balances: i) blowing snow sublimation losses, and ii) wind flow representation. Sublimation calculations have poorly understood humidity feedbacks that vary considerably and mathematical representations of alpine windflow vary in complexity - these differences introduce uncertainty. To better estimate and restrain this uncertainty, a variety of physically based, spatially distributed snowmelt models that consider the physics of wind redistribution and sublimation of blowing snow were evaluated for their ability to simulate seasonal snow distribution and melt patterns in a windy alpine environment in the Canadian Rockies. The primary difference in the snow models was their calculation of blowing snow sublimation losses which ranged from large to small estimates. To examine the uncertainty introduced by windflow calculations on the snow model simulations, each model was forced with output from windflow models of varying computational complexity and physical realism from a terrain-based empirical interpolation of station observations to a simple turbulence model to a computational fluid dynamics model that solves for the Navier-Stokes equations. The high-resolution snow simulations were run over a 1 km2 spatial extent centred on a ridgetop meteorological station within the Marmot Creek Research basin, Alberta, Canada. The three windflow simulations all produced reasonable results compared to wind speeds measured on two opposing slopes (bias better than ×0.3 m s-1; RMSE < 1.1 m s-1), however there was great sensitivity in SWE simulated by the snow models to the driving windflow simulation used. Specifically, there were distinct differences in the magnitude and location of snow drifts from all snow models that depended on the windflow scheme. When compared to measurements from airborne LiDAR, snow surveys, and automated snow depth

  2. Measurements of CO in an aircraft experiment and their correlation with biomass burning and air mass origin in South America

    NASA Astrophysics Data System (ADS)

    Boian, C.; Kirchhoff, V. W. J. H.

    Carbon monoxide (CO) measurements are obtained in an aircraft experiment during 1-7 September 2000, conducted over Central Brazil in a special region of anticyclonic circulation. This is a typical transport regime during the dry season (July-September), when intense biomass burning occurs, and which gives origin to the transport of burning poluents from the source to distant regions. This aircraft experiment included in situ measurements of CO concentrations in three different scenarios: (1) areas of fresh biomass burning air masses, or source areas; (2) areas of aged biomass burning air masses; and (3) areas of clean air or pristine air masses. The largest CO concentrations were of the order of 450 ppbv in the source region near Conceicao do Araguaia (PA), and the smallest value near 100 ppbv, was found in pristine air masses, for example, near the northeast coastline (clean air, or background region). The observed concentrations were compared to the number of fire pixels seen by the AVHRR satellite instrument. Backward isentropic trajectories were used to determine the origin of the air masses at each sampling point. From the association of the observed CO mixing ratios, fire pixels and air mass trajectories, the previous scenarios may be subdivided as follows: (1a) source regions of biomass burning with large CO concentrations; (1b) regions with few local fire pixels and absence of contributions by transport. Areas with these characteristics include the northeast region of Brazil; (1c) regions close to the source region and strongly affected by transport (region of Para and Amazonas); (2) regions that have a consistent convergence of air masses, that have traveled over biomass burning areas during a few days (western part of the Cerrado region); (3a) Pristine air masses with origin from the ocean; (3b) regions with convergent transport that has passed over areas of no biomass burning, such as frontal weather systems in the southern regions.

  3. Design of an optical system for a 5th generation multi-spectral air-to-air missile considering the imaging performance degradation due to the aerodynamic heating

    NASA Astrophysics Data System (ADS)

    Leite, Paulo R., Jr.; da Silva, Maurício; Paoli, Eduardo T.

    2009-05-01

    An air-to-air missile is always submitted to extremes conditions of temperature, such as a hot runway in the desert dropping down to very cold conditions at high altitudes. It is evident that the optical system must be able to provide satisfactory image quality under any circumstances without causing any major degradation to the image. Under this perspective, two different designs of optical systems will be considered for this missile: one catadioptric, using a modified Cassegrain telescope and another one purely dioptric. Both optical systems must be able to focus energy in two different arrays of detectors, one for the near infrared radiation and the other one for the medium infrared. Due to the special missile flight profile, the temperature operational range will be determined and considered in order to design and athermalize the optical systems. Due to the large temperatures range, the missile optical system will experience deformation effects that will cause defocus and image degradation. A correct choice of materials, including the telescope body and dome shroud must be determined to minimize the defocus effect. Also a thermal compensator ought to be strategically placed on both designs to provide focus correction for all the temperatures range. Following that, the optical designs will be analyzed for effects of stray light and ghost image to find out what are the most suitable absorbing paint and anti-reflective coatings to be used. In the last step, both systems will be classified accordingly to their characteristics of performance, weight, size, viability and price and the best will integrate the missile optical system.

  4. On the origin and destination of atmospheric moisture and air mass over the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Xu, Xiang-De; Yang, Shuai; Zhang, Wei

    2012-12-01

    The Tibet Plateau (TP) is a key region that imposes profound impacts on the atmospheric water cycle and energy budget of Asia, even the global climate. In this work, we develop a climatology of origin (destination) of air mass and moisture transported to (from) the TP using a Lagrangian moisture diagnosis combined with the forward and backward atmospheric tracking schemes. The climatology is derived from 6-h particle positions based on 5-year (2005-2009) seasonal summer trajectory dataset from the Lagrangian particle dispersion model FLEXPART using NCEP/GFS data as input, where the regional model atmosphere was globally filled with particles. The results show that (1) the dominant origin of the moisture supplied to the TP is a narrow tropical-subtropical band in the extended Arabian Sea covering a long distance from the Indian subcontinent to the Southern Hemisphere. Two additional moisture sources are located in the northwestern part of TP and the Bay of Bengal and play a secondary role. This result indicates that the moisture transporting to the TP more depends on the Indian summer monsoon controlled by large-scale circulation. (2) The moisture departing from the TP can be transported rapidly to East Asia, including East China, Korea, Japan, and even East Pacific. The qualitative similarity between the regions of diagnosed moisture loss and the pattern of the observed precipitation highlights the robustness of the role of the TP on precipitation over East Asia. (3) In contrast to the moisture origin confined in the low level, the origin and fate of whole column air mass over the TP is largely controlled by a strong high-level Asian anticyclone. The results show that the TP is a crossroad of air mass where air enters mainly from the northwest and northeast and continues in two separate streams: one goes southwestwards over the Indian Ocean and the other southeastwards through western North Pacific. Both of them partly enter the trade wind zone, which manifests the

  5. Influence of air mass origin on aerosol properties at a remote Michigan forest site

    NASA Astrophysics Data System (ADS)

    VanReken, T. M.; Mwaniki, G. R.; Wallace, H. W.; Pressley, S. N.; Erickson, M. H.; Jobson, B. T.; Lamb, B. K.

    2015-04-01

    The northern Great Lakes region of North America is a large, relatively pristine area. To date, there has only been limited study of the atmospheric aerosol in this region. During summer 2009, a detailed characterization of the atmospheric aerosol was conducted at the University of Michigan Biological Station (UMBS) as part of the Community Atmosphere-Biosphere Interactions Experiment (CABINEX). Measurements included particle size distribution, water-soluble composition, and CCN activity. Aerosol properties were strongly dependent on the origin of the air masses reaching the site. For ∼60% of the study period, air was transported from sparsely populated regions to the northwest. During these times aerosol loadings were low, with mean number and volume concentrations of 1630 cm-3 and 1.91 μm3 cm-3, respectively. The aerosol during clean periods was dominated by organics, and exhibited low hygroscopicities (mean κ = 0.18 at s = 0.3%). When air was from more populated regions to the east and south (∼29% of the time), aerosol properties reflected a stronger anthropogenic influence, with 85% greater particle number concentrations, 2.5 times greater aerosol volume, six times more sulfate mass, and increased hygroscopicity (mean k = 0.24 at s = 0.3%). These trends are have the potential to influence forest-atmosphere interactions and should be targeted for future study.

  6. A multivariate/chemical mass balance model for air pollution in China: A hybrid methodology

    SciTech Connect

    Zelenka, M.P.

    1992-01-01

    This research explores the possibility of using a two step method of identifying and quantifying air pollution emissions in an urban environment. The procedure uses a mathematical model called Target Transformation Factor Analysis (TTFA) to estimate source profiles using ambient trace element air concentration data. A source profile is analogous to a fingerprint since it is unique to each source of air pollution. It is important to use source profiles that are measured or estimated for the specific location under study. The profiles estimated by TTFA are then employed in a Chemical Mass Balance (CMB) source apportionment analysis for the airshed. Other known sources are estimated using source signatures from the literature. Applying the TTFA and CMB models in this fashion is called receptor modeling. Generically, a receptor model is the combination of measured air pollution concentration data with a numerical technique which apportions the measured air pollution among distinct source types. The results show that TTFA can be used to provide quantitative estimates of air pollution source profiles for an urban center in China. The number of profiles for unique source types was limited for this data set since emissions from certain types of sources co-varied during each sampling day. Consequently, the CMB analyses that applied the TTFA source profiles needed to be supplemented with standard US EPA source profiles. The application of TTFA for estimating source profiles from ambient data and the subsequent use of those profiles in CMB analyses with source profiles obtained from the EPA's source library can improve the statistical quality of the source apportionment analysis. TTFA can identify source categories of airborne pollution for specific cities, as well as give quantitative data on the composition of the emissions from those source types.

  7. Time-Variable Gravity Signal due to Extratropic Pacific Water Mass Redistribution

    NASA Technical Reports Server (NTRS)

    Chao, B. F.; Boy, J. -P.; Cox, C. M.; Au, A. Y.

    2003-01-01

    Using the satellite-laser-ranging (SLR) data, Cox and Chao [2002] reported the detection of a large post-1998 anomaly (in the form of a positive jump) in the time series of Earth s lowest-degree gravity harmonic 52, or the dynamic oblateness. Among several groups now examining the mass redistribution in the global geophysical fluids in search of the cause(s), we report here a temporally coinciding anomalies found in the extratropic north + south Pacific basins. Clearly seen in the leading EOFPC mode for extratropic Pacific, these anomalies occurred in sea-surface height, sea-surface temperature, and temperature- and salinity-depth profiles. We based our analysis on two different data sources: TOPEX/Poseidon altimetry, and the ECCO ocean general circulation model output assimilating T/P data. The magnitude of these changes, when converted to equivalent J2 change, appears to be a few times too small to explain the observed J2 directly. These findings, and the fact that the anomalies occurred following the strong 1997-98 El Nino, suggest strong geophysical connection of the interannual-to-decadal variation of 52 with the Pacific Decadal Oscillation (PDO) and the ultimate global-change processes that cause PDO. More work is underway, and additional independent data sources are examined, paying close attention to the fact that the J2 anomaly has been reversing back to normal since 2001. These include: (1) cryospheric contributions (melting of glaciers and ice sheets); (2) land hydrological contributions; (3) polar sea influences ( e g , via deep flow); (4) fluid flow in Earth's core; (5) time-variable gravity signals from SLR in higher harmonic degree/order, including J3,J4, (2,1), and (2,2) coefficients, considering their lower signal-to-noise ratios; (6) Earth rotation data in terms of length-of-day and polar motion.

  8. Time-variable gravity signal due to extratropic Pacific water mass redistribution

    NASA Astrophysics Data System (ADS)

    Chao, B. F.; Boy, J.-P.; Cox, C.; Au, A.

    2003-04-01

    Using the satellite-laser-ranging (SLR) data, Cox and Chao [2002] reported the detection of a large post-1998 anomaly (in the form of a positive "jump") in the time series of Earth's lowest-degree gravity harmonic J2, or the dynamic oblateness. Among several groups now examining the mass redistribution in the global geophysical fluids in search of the cause(s), we report here a temporally coinciding anomalies found in the extratropic north + south Pacific basins. Clearly seen in the leading EOF/PC mode for extratropic Pacific, these anomalies occurred in sea-surface height, sea-surface temperature, and temperature- and salinity-depth profiles. We based our analysis on two different data sources: TOPEX/Poseidon altimetry, and the ECCO ocean general circulation model output assimilating T/P data. The magnitude of these changes, when converted to equivalent J2 change, appears to be a few times too small to explain the observed J2 directly. These findings, and the fact that the anomalies occurred following the strong 1997-98 El Nino, suggest strong geophysical connection of the interannual-to-decadal variation of J2 with the Pacific Decadal Oscillation (PDO) and the ultimate global-change processes that cause PDO. More work is underway, and additional independent data sources are examined, paying close attention to the fact that the J2 anomaly has been reversing back to "normal" since 2001. These include: (1) cryospheric contributions (melting of glaciers and ice sheets); (2) land hydrological contributions; (3) polar sea influences (e.g., via deep flow); (4) fluid flow in Earth's core; (5) time-variable gravity signals from SLR in higher harmonic degree/order, including J3, J4, (2,1), and (2,2) coefficients, considering their lower signal-to-noise ratios; (6) Earth rotation data in terms of length-of-day and polar motion.

  9. Electrochemical Surface Potential due to Classical Point Charge Models Drives Anion Adsorption to the Air-Water Interface

    SciTech Connect

    Baer, Marcel D.; Stern, Abraham C.; Levin, Yan; Tobias, Douglas J.; Mundy, Christopher J.

    2012-06-07

    Herein, we present research that suggests that the underlying physics that drive simple empirical models of anions (e.g. point charge, no polarization) to the air-water interface, with water described by SPC/E, or related partial charge models is different than when both ions and water are modeled with quantum mechanical based interactions. Specifically, we will show that the driving force of ions to the air-water interface for point charge models results from both cavitation and the negative electrochemical surface potential. We will demonstrate that we can fully characterize the role of the free energy due to the electrochemical surface potential computed from simple empirical models and its role in ionic adsorption within the context of dielectric continuum theory (DCT). Our research suggests that a significant part of the electrochemical surface potential in empirical models appears to be an artifact of the failure of point charge models in the vicinity of a broken symmetry. This work was supported by the U.S. Department of Energy‘s (DOE) Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is operated for the Department of Energy by Battelle.

  10. Astronaut Mamoru Mohri Leaves Patrick Air Base After the Scrub of STS-99 Due to Mechanical Failure

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The primary objective of the STS-99 mission was to complete high resolution mapping of large sections of the Earth's surface using the Shuttle Radar Topography Mission (SRTM), a specially modified radar system. This radar system produced unrivaled 3-D images of the Earth's Surface. The mission was launched at 12:31 on February 11, 2000 onboard the space shuttle Endeavour, and led by Commander Kevin Kregel. The crew was Pilot Dominic L. Pudwill Gorie and Mission Specialists Janet L. Kavandi, Janice E. Voss, Mamoru Mohri from the National Space Development Agency (Japanese Space Agency), and Gerhard P. J. Thiele from DARA (German Space Agency). This videotape shows Mamoru Mohri boarding a plane at Patrick Air Base after the scrub of the mission due to mechanical problems. Prior to his departure, he answers a few questions from members of the Japanese press who had gathered for his departure.

  11. Effect of the relative optical air mass and the clearness index on solar erythemal UV irradiance.

    PubMed

    Moreno, J C; Serrano, M A; Cañada, J; Gurrea, G; Utrillas, M P

    2014-09-01

    This paper analyses the effects of the clearness index (Kt) and the relative optical air mass (mr) on erythemal UV irradiance (UVER). The UVER measurements were made in Valencia (Spain) from 6:00 am to 6:00 pm between June 2003 and December 2012 and (140,000 data points). Firstly, two models were used to calculate values for the erythemal ultraviolet irradiance clearness index (KtUVER) as a function of the global irradiance clearness index (Kt). Secondly, a potential regression model to measure the KtUVER as a function of the relative optical air mass was studied. The coefficients of this regression were evaluated for clear and cloudy days, as well as for days with high and low ozone levels. Thirdly, an analysis was made of the relationship between the two effects in the experimental database, with it being found that the highest degree of agreement, or the joint highest frequencies, are located in the optical mass range mr∈[1.0, 1.2] and the clearness index range of Kt∈[0.8, 1.0]. This is useful for establishing the ranges of parameters where models are more efficient. Simple equations have been tested that can provide additional information for the engineering projects concerning thermal installations. Fourthly, a high dispersion of radiation data was observed for intermediate values of the clearness for UV and UVER. PMID:24911276

  12. Calibration of Dissolved Noble Gas Mass Spectrometric Measurements by an Air-Water Equilibration System

    NASA Astrophysics Data System (ADS)

    Hillegonds, Darren; Matsumoto, Takuya; Jaklitsch, Manfred; Han, Liang-Feng; Klaus, Philipp; Wassenaar, Leonard; Aggarwal, Pradeep

    2013-04-01

    Precise measurements by mass spectrometry of dissolved noble gases (He, Ar, Ne, Kr, Xe) in water samples require careful calibration against laboratory standards with known concentrations. Currently, air pipettes are used for day-to-day calibrations, making estimation of overall analytical uncertainties for dissolved noble gas measurements in water difficult. Air equilibrated water (AEW) is often used as a matrix-equivalent laboratory standard for dissolved gases in groundwater, because of the well-known and constant fractions of noble gases in the atmosphere. AEW standards, however, are only useful if the temperature and pressure of the gas-water equilibrium can be controlled and measured precisely (i.e., to better than 0.5%); contamination and partial sample degassing must also be prevented during sampling. Here we present the details of a new custom air-water equilibration system which consists of an insulated 600 liter tank filled with deionized water, held isothermally at a precise target temperature (<0.05 °C) through the use of a heat exchanger. The temperature and total dissolved gas of the water in the tank are monitored continually, as are atmospheric pressure and air temperature in the laboratory. Different noble gas concentration standards can be reliably produced by accurately controlling the water temperature of the equilibration system. Equilibration characteristics and reproducibility of this system for production of copper tubes containing known amounts of noble gases will be presented.

  13. Seasonal variability of tritium and ion concentrations in rain at Kumamoto, Japan and back-trajectory analysis of air mass

    SciTech Connect

    Momoshima, N.; Sugihara, S.; Toyoshima, T.; Nagao, Y.; Takahashi, M.; Nakamura, Y.

    2008-07-15

    Tritium and major ion concentrations in rain were analyzed in Kumamoto (Japan)) between 2001 and 2006 to examine present tritium concentration and seasonal variation. The average tritium concentration was 0.36 {+-} 0.19 Bq/L (n=104) and higher tritium concentrations were observed in spring than the other seasons. Among the ions, non-sea-salt (nss) SO{sub 4}{sup 2}'- showed higher concentration in winter while other ions did not show marked increase in winter. Based on the back-trajectory analyses of air masses, the increase in tritium concentrations in spring arises from downward movement of naturally produced tritium from stratosphere to troposphere, while the increase of the nss-SO{sub 4}{sup 2-} concentrations in winter is due to long range transport of pollutants from China to Japan. (authors)

  14. Community air monitoring for pesticides-part 2: multiresidue determination of pesticides in air by gas chromatography, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry.

    PubMed

    Hengel, Matt; Lee, P

    2014-03-01

    Two multiresidue methods were developed to determine pesticides in air collected in California. Pesticides were trapped using XAD-4 resin and extracted with ethyl acetate. Based on an analytical method from the University of California Davis Trace Analytical Laboratory, pesticides were detected by analyzing the extract by gas chromatography-mass spectrometry (GC-MS) to determine chlorothalonil, chlorthal-dimethyl, cycloate, dicloran, dicofol, EPTC, ethalfluralin, iprodione, mefenoxam, metolachlor, PCNB, permethrin, pronamide, simazine, trifluralin, and vinclozolin. A GC with a flame photometric detector was used to determine chlorpyrifos, chlorpyrifos oxon, diazinon, diazinon oxon, dimethoate, dimethoate oxon, fonophos, fonophos oxon, malathion, malathion oxon, naled, and oxydemeton. Trapping efficiencies ranged from 78 to 92 % for low level (0.5 μg) and 37-104 % for high level (50 and 100 μg) recoveries. Little to no degradation of compounds occurred over 31 days; recoveries ranged from 78 to 113 %. In the California Department of Food and Agriculture (CDFA) method, pesticides were detected by analyzing the extract by GC-MS to determine chlorothalonil, chlorpyrifos, cypermethrin, dichlorvos, dicofol, endosulfan 1, endosulfan sulfate, oxyfluorfen, permethrin, propargite, and trifluralin. A liquid chromatograph coupled to a MS was used to determine azinphos-methyl, chloropyrifos oxon, DEF, diazinon, diazinon oxon, dimethoate, dimethoate oxon, diuron, EPTC, malathion, malathion oxon, metolachlor, molinate, norflurazon, oryzalin, phosmet, propanil, simazine and thiobencarb. Trapping efficiencies for compounds determined by the CDFA method ranged from 10 to 113, 22 to 114, and 56 to 132 % for 10, 5, and 2 μg spikes, respectively. Storage tests yielded 70-170 % recovery for up to 28 days. These multiresidue methods represent flexible, sensitive, accurate, and cost-effective ways to determine residues of various pesticides in ambient air. PMID:24370860

  15. Intercomparison between satellite-derived aerosol optical thickness and PM2.5 mass: Implications for air quality studies

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Christopher, Sundar A.

    2003-11-01

    We explore the relationship between column aerosol optical thickness (AOT) derived from the Moderate Resolution Imaging SpectroRadiometer (MODIS) on the Terra/Aqua satellites and hourly fine particulate mass (PM2.5) measured at the surface at seven locations in Jefferson county, Alabama for 2002. Results indicate that there is a good correlation between the satellite-derived AOT and PM2.5 (linear correlation coefficient, R = 0.7) indicating that most of the aerosols are in the well-mixed lower boundary layer during the satellite overpass times. There is excellent agreement between the monthly mean PM2.5 and MODIS AOT (R > 0.9), with maximum values during the summer months due to enhanced photolysis. The PM2.5 has a distinct diurnal signature with maxima in the early morning (6:00 ~ 8:00AM) due to increased traffic flow and restricted mixing depths during these hours. Using simple empirical linear relationships derived between the MODIS AOT and 24hr mean PM2.5 we show that the MODIS AOT can be used quantitatively to estimate air quality categories as defined by the U.S. Environmental Protection Agency (EPA) with an accuracy of more than 90% in cloud-free conditions. We discuss the factors that affect the correlation between satellite-derived AOT and PM2.5 mass, and emphasize that more research is needed before applying these methods and results over other areas.

  16. Influence of dissolved humic substances on the mass transfer of organic compounds across the air-water interface.

    PubMed

    Ramus, Ksenia; Kopinke, Frank-Dieter; Georgi, Anett

    2012-01-01

    The effect of dissolved humic substances (DHS) on the rate of water-gas exchange of two volatile organic compounds was studied under various conditions of agitation intensity, solution pH and ionic strength. Mass-transfer coefficients were determined from the rate of depletion of model compounds from an apparatus containing a stirred aqueous solution with continuous purging of the headspace above the solution (dynamic system). Under these conditions, the overall transfer rate is controlled by the mass-transfer resistance on the water side of the water-gas interface. The experimental results show that the presence of DHS hinders the transport of the organic molecules from the water into the gas phase under all investigated conditions. Mass-transfer coefficients were significantly reduced even by low, environmentally relevant concentrations of DHS. The retardation effect increased with increasing DHS concentration. The magnitude of the retardation effect on water-gas exchange was compared for Suwannee River fulvic and humic acids, a commercially available leonardite humic acid and two synthetic surfactants. The observed results are in accordance with the concept of hydrodynamic effects. Surface pressure forces due to surface film formation change the hydrodynamic characteristics of water motion at the water-air interface and thus impede surface renewal. PMID:22051345

  17. [Intraepidermal mass of M. leprae in a case of seborrheic keratosis due to Hansen's disease (LLs)].

    PubMed

    Yajima, M; Suzuki, K; Wen, M; Yamada, N; Asano, G

    1995-11-01

    A 67-year-old patient has had exanthema in the lower right limb since 51 years ago (16 years old at onset), which underwent repeated remission and recurrence. At present, he has bilateral symmetrical widespread infiltrating exanthema and asymmetrical marked neuralhypertrophy, and has been diagnosed typical LLs (His father had the same disease). The exanthema recurred several years ago, and the patient is being treated for Hansen's disease. He had a dark brown flat elevation with a rough surface and the size of a small finger tip in his right abdominal skin for approximately 20 years. A biopsy was performed, and the specimen was fixed in 10% formalin and paraffin sections were prepared for histopathologic examination. A part of the specimen was processed forscanning electron microscopic examination. Seborrheic keratosis was diagnosed by H & E staining. Acid-fast (FITE) staining, immunohistochemical staining (keratin, S-100 protein, anti-PGL antibody and anti-BCG antibody) and scanning electron microscopy revealed the presence of bacteria (M. leprae) in the dermal foam cells, the matrix with a banded structure and the squamous epithelial cells which normally lack phagocytosis function. Compared to the basal cells of normal epidermis, the basal cells located adjacent to the dermis affected with seborrheic keratosis showed increased proliferation and more marked characteristics of a germinative cell. The degree of differentiation of the basal cells appeared regressed, and they probably possessed augmented phagocytic activity. The phagocytosed bacteria were probably carried by the epidermal cell cycle toward the surface layer. However, bacteria could not be found in the stratum corneum, probably due to an association with the lysosome. PMID:8582883

  18. Determination of the effect of transfer between vacuum and air on mass standards of platinum-iridium and stainless steel

    NASA Astrophysics Data System (ADS)

    Davidson, Stuart

    2010-08-01

    This paper reports work undertaken to assess the change in the mass values of stainless steel and platinum-iridium weights transferred between air and vacuum and to determine the repeatability of this change. Sets of kilogram transfer standards, manufactured from stainless steel and platinum-iridium and with different surface areas, were used to determine the effect of transfer between air and vacuum on the values of the mass standards. The SI unit of mass is the only unit of the seven base SI quantities which is still defined in terms of an artefact rather than by relation to a fundamental physical constant. Work is underway to identify a means of deriving the SI unit of mass from fundamental constants and at present the two principal approaches are the International Avogadro Coordination and the watt balance projects. Both of these approaches involve realizing a kilogram in vacuum and therefore the traceability from a kilogram realized in vacuum to mass standards in air is crucial to the effective dissemination of the mass scale. The work reported here characterizes the changes in mass values of standards on transfer between air and vacuum and thus will enable traceability to be established for an in-air mass scale based on a definition of the unit in vacuum.

  19. Crustal Rebound due to Lake Mass Changes Measured by InSAR: Constraints on Lithosphere Rheology

    NASA Astrophysics Data System (ADS)

    Doin, M. P.; Twardzik, C.; Cavalié, O.; Lasserre, C.

    2015-12-01

    SAR interferometry has proven to be a reliable method for detecting small displacements due to ground subsidence. Here, we relate ground motion around the lake Mead (Nevada, USA) and lake Siling Co (Tibet, China) measured by InSAR to water loading in order to constrain the rheology of the lithosphere.Lake Mead, an artificial reservoir, has been filled with water in 1935. We analyzed ~500 interferograms based on 62 ERS images and on 40 ENVISAT images acquired between 1992 and 2010. Interferograms are inverted to solve for the time series of ground motion in the lake Mead area. Temporal smoothing allows to reduce the turbulent atmospheric delays. Spatio-temporal series of the deformation from 1992 to 2010 show a broad subsidence pattern correlated with lake level from 1992 to 2010. We model the deformation, taking into account the water and sediment loading history of the lake since 1935. The two-layer visco-elastic model proposed by Kaufmann and Amelung (2000), with a mantle viscosity of 1018 Pa s, adjusts well the data up to 2001, but overpredicts the deformation after 2001. We will discuss the models that could explain the deformation evolution. The Siling Co lake is the largest endorheic lake in Central Tibet. In 1972-1999 its water level remained stable, while it increased by about 1.0~m/yr in the period 2000-2006. The increased rate gradually stepped down to 0.2~m/yr in 2007-2011. We analysed 107 ERS and Envisat SAR images during the period 1992-2011. The deformation amplitude closely follows the lake level temporal evolution, except that subsidence continues in 2008-2011, while the lake level stagnated. This temporal evolution suggests a non elastic relaxation process taking place at a decade time-scale. Phase delay maps are used to constrain possible layered visco-elastic rheological models. An elastic model could partly explain the observed subsidence rate if elastic moduli are about twice lower than those extracted from Vp/Vs profiles. The surface

  20. A thunderstorm cell-lightning activity analysis: The new concept of air mass catchment

    NASA Astrophysics Data System (ADS)

    Mona, Tamás; Horváth, Ákos; Ács, Ferenc

    2016-03-01

    Thunderstorm cell-lightning activity is discussed in terms of analysing a thunderstorm's lightning frequency-equipotential temperature relationship. Thunderstorms were tracked using Doppler radars in five-minute time steps. Lightning is assigned to the nearest thunderstorm cell, it is characterised by lightning frequency data using LINET. Equipotential temperature is not directly estimated, instead the notion of air mass catchment is introduced to represent it. It is shown in this paper that the thunderstorm cell with maximum lightning frequency in the current time step is almost always the so-called leading storm cell. The lightning frequency activity of the non-leading storm cells is not significant.

  1. Studies on potential emission of hazardous gases due to uncontrolled open-air burning of waste vehicle tyres and their possible impacts on the environment

    NASA Astrophysics Data System (ADS)

    Shakya, Pawan R.; Shrestha, Pratima; Tamrakar, Chirika S.; Bhattarai, Pradeep K.

    Uncontrolled open-air burning of waste vehicle tyres causing environmental pollution has become a popular practice in Nepal despite official ban considering the environment and public health hazards. In this study, an experimental model was set up in a laboratory scale in an attempt to understand the potential emission of hazardous gases such as CO, SO 2 and NO 2 due to such activities in Kathmandu Valley and their possible impacts on the environment. For this purpose, four types of tyre were collected representing two from passenger car and two from motorbike category. The emission level of CO in the tyre smoke was measured with a CO gas detector tube while SO 2 and NO 2 were determined by UV-visible spectrophotometer. Among the three types of the gases analyzed, SO 2 was emitted in significantly high levels by all the representative tyre samples. The emission levels of CO, SO 2 and NO 2 ranged from 21to 49, 102to 820 and 3to 9 μg g -1, respectively. Results revealed that the emission levels also varied with the tyre types and qualities. The potential emission of the hazardous gases per representative scrap tyre mass was also estimated. Results indicate that the gaseous pollutants due to the tyre fires could make a significant contribution for deterioration of the environmental condition of the Valley or elsewhere.

  2. Diode laser-based air mass flux sensor for subsonic aeropropulsion inlets.

    PubMed

    Miller, M F; Kessler, W J; Allen, M G

    1996-08-20

    An optical air mass flux sensor based on a compact, room-temperature diode laser in a fiber-coupled delivery system has been tested on a full-scale gas turbine engine. The sensor is based on simultaneous measurements of O(2) density and Doppler-shifted velocity along a line of sight across the inlet duct. Extensive tests spanning engine power levels from idle to full afterburner demonstrate accuracy and precision of the order of 1-2% of full scale in density, velocity, and mass flux. The precision-limited velocity at atmospheric pressure was as low as 40 cm/s. Multiple data-reduction procedures are quantitatively compared to suggest optimal strategies for flight sensor packages. PMID:21102916

  3. Diode laser-based air mass flux sensor for subsonic aeropropulsion inlets

    NASA Astrophysics Data System (ADS)

    Miller, Michael F.; Kessler, William J.; Allen, Mark G.

    1996-08-01

    An optical air mass flux sensor based on a compact, room-temperature diode laser in a fiber-coupled delivery system has been tested on a full-scale gas turbine engine. The sensor is based on simultaneous measurements of O 2 density and Doppler-shifted velocity along a line of sight across the inlet duct. Extensive tests spanning engine power levels from idle to full afterburner demonstrate accuracy and precision of the order of 1 2 of full scale in density, velocity, and mass flux. The precision-limited velocity at atmospheric pressure was as low as 40 cm s. Multiple data-reduction procedures are quantitatively compared to suggest optimal strategies for flight sensor packages.

  4. Uncertainty evaluation of mass values determined by electronic balances in analytical chemistry: a new method to correct for air buoyancy.

    PubMed

    Wunderli, S; Fortunato, G; Reichmuth, A; Richard, Ph

    2003-06-01

    A new method to correct for the largest systematic influence in mass determination-air buoyancy-is outlined. A full description of the most relevant influence parameters is given and the combined measurement uncertainty is evaluated according to the ISO-GUM approach [1]. A new correction method for air buoyancy using an artefact is presented. This method has the advantage that only a mass artefact is used to correct for air buoyancy. The classical approach demands the determination of the air density and therefore suitable equipment to measure at least the air temperature, the air pressure and the relative air humidity within the demanded uncertainties (i.e. three independent measurement tasks have to be performed simultaneously). The calculated uncertainty is lower for the classical method. However a field laboratory may not always be in possession of fully traceable measurement systems for these room climatic parameters.A comparison of three approaches applied to the calculation of the combined uncertainty of mass values is presented. Namely the classical determination of air buoyancy, the artefact method, and the neglecting of this systematic effect as proposed in the new EURACHEM/CITAC guide [2]. The artefact method is suitable for high-precision measurement in analytical chemistry and especially for the production of certified reference materials, reference values and analytical chemical reference materials. The method could also be used either for volume determination of solids or for air density measurement by an independent method. PMID:12732918

  5. VOC Composition of Air Masses Transported from Asia to the U.S. West Coast

    NASA Astrophysics Data System (ADS)

    de Gouw, J.; Warneke, C.; Kuster, B.; Parrish, D.; Holloway, J.; Huebler, G.; Fehsenfeld, F.

    2002-12-01

    Airborne measurements of volatile organic compounds (VOCs) were performed using a proton-transfer-reaction mass spectrometer (PTR-MS) operated onboard a NOAA WP-3 aircraft during the Intercontinental Transport and Chemical Transformation (ITCT) experiment in 2002. Enhancements of acetone (CH3COCH3), methanol (CH3OH), acetonitrile (CH3CN) and in some cases benzene were observed in air masses that were impacted by outflow from Asia. The enhancement ratios with respect to carbon monoxide are compared to emission factors for fossil fuel combustion and biomass burning, which gives some insight into the sources responsible for the pollution. The observed mixing ratios for acetone, methanol and in particular acetonitrile were generally reduced in the marine boundary layer, suggesting the presence of an ocean uptake sink. The ocean uptake of acetonitrile was found to be particularly efficient in a zone with upwelling water off of the U.S. west coast. Reduced mixing ratios of acetone and methanol were observed in a stratospheric intrusion. This observation gives some information about the lifetime of these VOCs in the stratosphere. Enhanced concentrations of aromatic hydrocarbons were observed in air masses that were impacted by urban sources in California. The ratio between the concentrations of benzene, toluene and higher aromatics indicated the degree of photochemical oxidation. PTR-MS only gives information about the mass of the ions produced by proton-transfer reactions between H3O+ and VOCs in the instrument. The identification of VOCs was confirmed by coupling a gas-chromatographic (GC) column to the instrument and post-flight GC-PTR-MS analyses of canister samples collected during the flights.

  6. Statistical treatment of fluctuations in the gravitational focusing of light due to stellar masses within a gravitational lens

    NASA Technical Reports Server (NTRS)

    Deguchi, Shuji; Watson, William D.

    1987-01-01

    When light from small, distant sources in the universe is gravitationally focused by an intervening galaxy, the gravitational lens can be influenced by the granularity of the matter distribution which is caused by the stellar (or other compact) masses in the galaxy. A largely analytic, statistical calculation for a gravitational lens due to a collection of compact masses - valid for sources of finite size and for large (as well as small) 'optical depths' for the lens - is developed to treat fluctuations in the light caused by such 'microfocusing' effects. Previous treatments have been either numerical simulations of the Monte Carlo type or limited to single-star (i.e., low-optical-depth) effects.

  7. Characterization of key aerosol, trace gas and meteorological properties and particle formation and growth processes dependent on air mass origins in coastal Southern Spain

    NASA Astrophysics Data System (ADS)

    Diesch, J.; Drewnick, F.; Sinha, V.; Williams, J.; Borrmann, S.

    2011-12-01

    The chemical composition and concentration of aerosols at a certain site can vary depending on season, the air mass source region and distance from sources. Regardless of the environment, new particle formation (NPF) events are one of the major sources for ultrafine particles which are potentially hazardous to human health. Grown particles are optically active and efficient CCN resulting in important implications for visibility and climate (Zhang et al., 2004). The study presented here is intended to provide information about various aspects of continental, urban and marine air masses reflected by wind patterns of the air arriving at the measurement site. Additionally we will be focusing on NPF events associated with different types of air masses affecting their emergence and temporal evolution. Measurements of the ambient aerosol, various trace gases and meteorological parameters were performed within the framework of the DOMINO (Diel Oxidant Mechanisms In relation to Nitrogen Oxides) project. The field campaign took place from mid-November to mid-December 2008 at the atmospheric research station "El Arenosillo" located at the interface between a natural park, industrial cities (Huelva, Seville) and the Atlantic Ocean. Number and mass as well as PAH and black carbon concentrations were measured in PM1 and size distribution instruments covered the size range 6 nm up to 32 μm. The chemical composition of the non-refractory submicron aerosol was measured by means of an Aerosol Mass Spectrometer (AMS). In order to evaluate the characteristics of different air masses linking local and regional sources as well as NPF processes, characteristic air mass types were classified dependent on backwards trajectory pathways and local meteorology. Large nuclei mode concentrations in the number size distribution were found within continental and urban influenced air mass types due to frequently occurring NPF events. Exploring individual production and sink variables, sulfuric

  8. Characteristics of dimethylsulfide, ozone, aerosols, and cloud condensation nuclei in air masses over the northwestern Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nagao, Ippei; Matsumoto, Kiyoshi; Tanaka, Hiroshi

    1999-05-01

    Long-term measurements of several trace gases and aerosols were carried out from December 1994 to October 1996 at Ogasawara Hahajima Island over the northwestern Pacific Ocean. The continental impact on the concentrations of sulfur compounds, ozone (O3), and cloud condensation nuclei (CCN) was estimated on the basis of the classification of air mass into seven types by isentropic trajectory analysis. From May to October, the air mass originating from the central North Pacific Ocean is predominant and regarded as the clean marine air for the concentrations of sulfur compounds and CCN. From the results of the molar ratio of methane sulfonic acid to non-sea-salt sulfate (NSS) and the positive correlation between dimethylsulfide (DMS) and CCN in this air mass it can be concluded that DMS largely contributes to the production of NSS and CCN. On the other hand, continental and anthropogenic substances are preferably transported to the northwestern Pacific Ocean by the predominant continental air mass from November to March. The enhancement of concentrations by the outflow from the Asian continent are estimated by a factor of 2.8 for O3, 3.9 for SO2, 3.5 for CCN activated at 0.5% supersaturation (0.5% CCN), 4.7 for 1.0% CCN, and 5.5 for NSS. Moreover, the CCN supersaturation spectra are also affected by the continental substances resulting in factor 2 of enhancement of cloud droplet number concentration. The diurnal variations of DMS and O3 for each air mass show a pattern of daytime minimum and nighttime maximum, which are typically found in remote ocean, even though those amplitudes are different for each air mass. Consequently, it can be concluded that the influence of nitric oxides (NOx) for the daytime O3 production and nitrate (NO3) radical for the nighttime oxidation of DMS are small even in the continental air mass.

  9. Numerical study of heat and mass transfer in an anisotropic porous enclosure due to constant heating and cooling

    SciTech Connect

    Bera, P.; Eswaran, V.; Singh, P.

    1998-12-01

    Combined heat and mass transfer in porous media occurs in many natural phenomena and engineering applications, such as the migration of moisture through air contained in insulation, the spreading of chemical pollutants in saturated soil, and the extraction of geothermal energy. Here, double-diffusive natural convective flow within a rectangular enclosure has been studied for an anisotropic porous medium using a non-Darcy extension. The principal direction of the permeability tensor has been taken oblique to the gravity vector. The spectral element method has been used to solve the problem numerically. The method has been validated using existing analytical and numerical results. Parametric studies are presented for isotropic and anisotropic cases for different fundamental parameters, e.g., buoyancy ratio, Lewis number, Rayleigh number, Darcy number. The results show that anisotropy causes significant changes in the Nusselt and Sherwood numbers. In particular, the present analysis shows that permeability orientation angle has a significant effect on the flow rate and, consequently, on the heat and mass transfer.

  10. Precipitation chemistry and corresponding transport patterns of influencing air masses at Huangshan Mountain in East China

    NASA Astrophysics Data System (ADS)

    Shi, ChunE; Deng, Xueliang; Yang, Yuanjian; Huang, Xiangrong; Wu, Biwen

    2014-09-01

    One hundred and ten samples of rainwater were collected for chemical analysis at the summit of Huangshan Mountain, a high-altitude site in East China, from July 2010 to June 2011. The volume-weighted-mean (VWM) pH for the whole sampling period was 5.03. SO{4/2-} and Ca2+ were the most abundant anion and cation, respectively. The ionic concentrations varied monthly with the highest concentrations in winter/spring and the lowest in summer. Evident inter-correlations were found among most ions, indicating the common sources for some species and fully mixing characteristics of the alpine precipitation chemistry. The VWM ratio of [SO{4/2-}]/[NO{3/-}] was 2.54, suggesting the acidity of rainwater comes from both nitric and sulfuric acids. Compared with contemporary observations at other alpine continental sites in China, the precipitation at Huangshan Mountain was the least polluted, with the lowest ionic concentrations. Trajectories to Huangshan Mountain on rainy days could be classified into six groups. The rainwater with influencing air masses originating in Mongolia was the most polluted with limited effect. The emissions of Jiangxi, Anhui, Zhejiang and Jiangsu provinces had a strong influence on the overall rain chemistry at Huangshan Mountain. The rainwater with influencing air masses from Inner Mongolia was heavily polluted by anthropogenic pollutants.

  11. Aerosol composition in a stagnant air mass impacted by dense fogs: preliminary results

    SciTech Connect

    Jacob, D.J.; Munger, J.W.; Waldman, J.M.; Hoffman, M.R.

    1984-01-01

    Over the last two winters, our research group has been investigating the chemical composition of fogwater and haze aerosol during wintertime stagnation episodes in the San Joaquin Valley of California. The valley is encompassed by mountain ranges. During the winter a strong subsidence inversion based below the natural boundaries of the valley restricts the ventilation of the air masses below the inversion. The residence time of an air parcel in the valley under these stagnation conditions is on the order of 8 days. Because the trapped air is very humid, stagnation episodes are associated with a persistent thick haze and frequent widespread nighttime fogs. During the winter 1982-1983 the authors sampled fog and haze at one site (Bakersfield); results from this preliminary study have been discussed in detail in a previous report. In the winter 1983-1984 the scale of the program was expanded in order to test hypotheses formulated as a result of first year data. The present paper first reports briefly on the 1982-1983 results and outlines the essential conclusions. They then describe the large-scale experiment conducted during the winter of 1983-1984, and discuss some preliminary fogwater data.

  12. Trends and sources vs air mass origins in a major city in South-western Europe: Implications for air quality management.

    PubMed

    Fernández-Camacho, R; de la Rosa, J D; Sánchez de la Campa, A M

    2016-05-15

    This study presents a 17-years air quality database comprised of different parameters corresponding to the largest city in the south of Spain (Seville) where atmospheric pollution is frequently attributed to traffic emissions and is directly affected by Saharan dust outbreaks. We identify the PM10 contributions from both natural and anthropogenic sources in this area associated to different air mass origins. Hourly, daily and seasonal variation of PM10 and gaseous pollutant concentrations (CO, NO2 and SO2), all of them showing negative trends during the study period, point to the traffic as one of the main sources of air pollution in Seville. Mineral dust, secondary inorganic compounds (SIC) and trace elements showed higher concentrations under North African (NAF) air mass origins than under Atlantic. We observe a decreasing trend in all chemical components of PM10 under both types of air masses, NAF and Atlantic. Principal component analysis using more frequent air masses in the area allows the identification of five PM10 sources: crustal, regional, marine, traffic and industrial. Natural sources play a more relevant role during NAF events (20.6 μg · m(-3)) than in Atlantic episodes (13.8 μg · m(-3)). The contribution of the anthropogenic sources under NAF doubles the one under Atlantic conditions (33.6 μg · m(-3) and 15.8 μg · m(-3), respectively). During Saharan dust outbreaks the frequent accumulation of local anthropogenic pollutants in the lower atmosphere results in poor air quality and an increased risk of mortality. The results are relevant when analysing the impact of anthropogenic emissions on the exposed population in large cities. The increase in potentially toxic elements during Saharan dust outbreaks should also be taken into account when discounting the number of exceedances attributable to non-anthropogenic or natural origins. PMID:26930305

  13. The influence of air temperature inversions on snowmelt and glacier mass-balance simulations, Ammassalik island, SE Greenland

    SciTech Connect

    Mernild, Sebastian Haugard; Liston, Glen

    2009-01-01

    In many applications, a realistic description of air temperature inversions is essential for accurate snow and glacier ice melt, and glacier mass-balance simulations. A physically based snow-evolution modeling system (SnowModel) was used to simulate eight years (1998/99 to 2005/06) of snow accumulation and snow and glacier ice ablation from numerous small coastal marginal glaciers on the SW-part of Ammassalik Island in SE Greenland. These glaciers are regularly influenced by inversions and sea breezes associated with the adjacent relatively low temperature and frequently ice-choked fjords and ocean. To account for the influence of these inversions on the spatiotemporal variation of air temperature and snow and glacier melt rates, temperature inversion routines were added to MircoMet, the meteorological distribution sub-model used in SnowModel. The inversions were observed and modeled to occur during 84% of the simulation period. Modeled inversions were defined not to occur during days with strong winds and high precipitation rates due to the potential of inversion break-up. Field observations showed inversions to extend from sea level to approximately 300 m a.s.l., and this inversion level was prescribed in the model simulations. Simulations with and without the inversion routines were compared. The inversion model produced air temperature distributions with warmer lower elevation areas and cooler higher elevation areas than without inversion routines due to the use of cold sea-breeze base temperature data from underneath the inversion. This yielded an up to 2 weeks earlier snowmelt in the lower areas and up to 1 to 3 weeks later snowmelt in the higher elevation areas of the simulation domain. Averaged mean annual modeled surface mass-balance for all glaciers (mainly located above the inversion layer) was -720 {+-} 620 mm w.eq. y{sup -1} for inversion simulations, and -880 {+-} 620 mm w.eq. y{sup -1} without the inversion routines, a difference of 160 mm w.eq. y

  14. Aerosols in polluted versus nonpolluted air masses Long-range transport and effects on clouds

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Van Valin, C. C.; Castillo, R. C.; Kadlecek, J. A.; Ganor, E.

    1986-01-01

    To assess the influence of anthropogenic aerosols on the physics and chemistry of clouds in the northeastern United States, aerosol and cloud-drop size distributions, elemental composition of aerosols as a function of size, and ionic content of cloud water were measured on Whiteface Mountain, NY, during the summers of 1981 and 1982. In several case studies, the data were cross-correlated with different air mass types - background continental, polluted continental, and maritime - that were advected to the sampling site. The results are the following: (1) Anthropogenic sources hundreds of kilometers upwind cause the small-particle (accumulation) mode number to increase from hundreds of thousands per cubic centimeter and the mass loading to increase from a few to several tens of micrograms per cubic meter, mostly in the form of sulfur aerosols. (2) A significant fraction of anthropogenic sulfur appears to act as cloud condensation nuclei (CCN) to affect the cloud drop concentration. (3) Clouds in Atlantic maritime air masses have cloud drop spectra that are markedly different from those measured in continental clouds. The drop concentration is significantly lower, and the drop size spectra are heavily skewed toward large drops. (4) Effects of anthropogenic pollutants on cloud water ionic composition are an increase of nitrate by a factor of 50, an increase of sulfate by more than one order of magnitude, and an increase of ammonium ion by a factor of 7. The net effect of the changes in ionic concentrations is an increase in cloud water acidity. An anion deficit even in maritime clouds suggests an unknown, possibly biogenic, source that could be responsible for a pH below neutral, which is frequently observed in nonpolluted clouds.

  15. Fullerene Soot in Eastern China Air: Results from Soot Particle-Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Wang, J.; Ge, X.; Chen, M.; Zhang, Q.; Yu, H.; Sun, Y.; Worsnop, D. R.; Collier, S.

    2015-12-01

    In this work, we present for the first time, the observation and quantification of fullerenes in ambient airborne particulate using an Aerodyne Soot Particle - Aerosol Mass Spectrometer (SP-AMS) deployed during 2015 winter in suburban Nanjing, a megacity in eastern China. The laser desorption and electron impact ionization techniques employed by the SP-AMS allow us to differentiate various fullerenes from other aerosol components. Mass spectrum of the identified fullerene soot is consisted by a series of high molecular weight carbon clusters (up to m/z of 2000 in this study), almost identical to the spectral features of commercially available fullerene soot, both with C70 and C60 clusters as the first and second most abundant species. This type of soot was observed throughout the entire study period, with an average mass loading of 0.18 μg/m3, accounting for 6.4% of the black carbon mass, 1.2% of the total organic mass. Temporal variation and diurnal pattern of fullerene soot are overall similar to those of black carbon, but are clearly different in some periods. Combining the positive matrix factorization, back-trajectory and analyses of the meteorological parameters, we identified the petrochemical industrial plants situating upwind from the sampling site, as the major source of fullerene soot. In this regard, our findings imply the ubiquitous presence of fullerene soot in ambient air of industry-influenced area, especially the oil and gas production regions. This study also offers new insights into the characterization of fullerenes from other environmental samples via the advanced SP-AMS technique.

  16. Ageing of organic electrical insulating materials due to radiation—II. Physical properties of a cycloaliphatic epoxy resin irradiated in moisture saturated air

    NASA Astrophysics Data System (ADS)

    Spadaro, G.; Calderaro, E.; Rizzo, G.

    Physical properties of a cycloaliphatic epoxy resin irradiated in moisture saturated air have been investigated. In particular dynamic-medical, dielectric and tensile measurements have been performed. The results suggest that at low irradiation doses the degradation, due to moisture absorption, predominates, whereas at high doses the main effect is an increase of the degree of crosslinking due to irradiation.

  17. The Use of Red Green Blue Air Mass Imagery to Investigate the Role of Stratospheric Air in a Non-Convective Wind Event

    NASA Technical Reports Server (NTRS)

    Berndt, E. B.; Zavodsky, B. T.; Moltham, A. L.; Folmer, M. J.; Jedlovec, G. J.

    2014-01-01

    The investigation of non-convective winds associated with passing extratropical cyclones and the formation of the sting jet in North Atlantic cyclones that impact Europe has been gaining interest. Sting jet research has been limited to North Atlantic cyclones that impact Europe because it is known to occur in Shapiro-Keyser cyclones and theory suggests it does not occur in Norwegian type cyclones. The global distribution of sting jet cyclones is unknown and questions remain as to whether cyclones with Shapiro-Keyser characteristics that impact the United States develop features similar to the sting jet. Therefore unique National Aeronautics and Space Administration (NASA) products were used to analyze an event that impacted the Northeast United States on 09 February 2013. Moderate Resolution Imaging Spectroradiometer (MODIS) Red Green Blue (RGB) Air Mass imagery and Atmospheric Infrared Sounder (AIRS) ozone data were used in conjunction with NASA's global Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis and higher-resolution regional 13-km Rapid Refresh (RAP) data to analyze the role of stratospheric air in producing high winds. The RGB Air Mass imagery and a new AIRS ozone anomaly product were used to confirm the presence of stratospheric air. Plan view and cross sectional plots of wind, potential vorticity, relative humidity, omega, and frontogenesis were used to analyze the relationship between stratospheric air and high surface winds during the event. Additionally, the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model was used to plot trajectories to determine the role of the conveyor belts in producing the high winds. Analyses of new satellite products, such as the RGB Air Mass imagery, show the utility of future GOES-R products in forecasting non-convective wind events.

  18. Number size distribution of aerosols at Mt. Huang and Nanjing in the Yangtze River Delta, China: Effects of air masses and characteristics of new particle formation

    NASA Astrophysics Data System (ADS)

    Wang, Honglei; Zhu, Bin; Shen, Lijuan; An, Junlin; Yin, Yan; Kang, Hanqing

    2014-12-01

    Aerosol number spectra in the range of 10 nm-10 μm were observed at Mt. Huang (Aug. 15-Sep. 15) and Nanjing (Oct. 13-Nov. 15) by a wide-range particle spectrometer (WPS) in 2011. Based on the backward trajectories obtained using the HYSPLIT model, the transport pathways of observed air masses during the study periods were classified into the following four groups: maritime air mass, continental air mass, marine-continental mixed air mass and local air mass. The variations in the aerosol number spectrum and the new particle formation (NPF) events for various types of air masses were discussed, along with meteorological data. The results showed that the average number concentration was 12,540 cm- 3 at Nanjing and only 2791 cm- 3 at Mt. Huang. The aerosol number concentration in Nanjing was 3-7 times higher than that in Mt. Huang; the large discrepancy was in the range of 10-100 nm. Different types of air masses had different effects on number concentration distribution. The number concentration of aerosols was higher in marine air masses, continental air masses and continental-marine mixed air masses at 10-50 nm, 100-500 nm and 50-200 nm, respectively. Under the four types of air masses, the aerosol size spectra had bimodal distributions in Nanjing and unimodal distributions in Mt. Huang (except under continental air masses: HT1). The effects of the diverse air masses on aerosol size segments of the concentration peak in Mt. Huang were stronger than those in Nanjing. The local air masses were dominant at these two sites and accounted for 44% of the total air masses. However, the aerosol number concentration was the lowest in Mt. Huang and the highest in Nanjing when local air masses were present. The number concentrations for foreign air masses increased at Mt. Huang and decreased at Nanjing. Different types of air masses had greater effects on the aerosol spectrum distribution at Mt. Huang than at Nanjing. During the NPF events, the particle growth rates at Mt

  19. A burn mass casualty event due to boiler room explosion on a cruise ship: preparedness and outcomes.

    PubMed

    Tekin, Akin; Namias, Nicholas; O'Keeffe, Terence; Pizano, Louis; Lynn, Mauricio; Prater-Varas, Robin; Quintana, Olga Delia; Borges, Leda; Ishii, Mary; Lee, Seong; Lopez, Peter; Lessner-Eisenberg, Sharon; Alvarez, Angel; Ellison, Tom; Sapnas, Katherine; Lefton, Jennifer; Ward, Charles Gillon

    2005-03-01

    The purpose of this study was to review our experience with a mass casualty incident resulting from a boiler room steam explosion aboard a cruise ship. Experience with major, moderate, and minor burns, steam inhalation, mass casualty response systems, and psychological sequelae will be discussed. Fifteen cruise ship employees were brought to the burn center after a boiler room explosion on a cruise ship. Eleven were triaged to the trauma resuscitation area and four to the surgical emergency room. Seven patients were intubated for respiratory distress or airway protection. Six patients had >80 per cent burns with steam inhalation, and all of these died. One of the 6 patients had 99 per cent burns with steam inhalation and died after withdrawal of support within the first several hours. All patients with major burns required escharotomy on arrival to trauma resuscitation. One patient died in the operating room, despite decompression by laparotomy for abdominal compartment syndrome and pericardiotomy via thoracotomy for cardiac tamponade. Four patients required crystalloid, 20,000 mls/m2-27,000 ml/m2 body surface area (BSA) in the first 48 hours to maintain blood pressure and urine output. Three of these four patients subsequently developed abdominal compartment syndrome and died in the first few days. The fourth patient of this group died after 26 days due to sepsis. Five patients had 13-20 per cent bums and four patients had less than 10 per cent burns. Two of the patients with 20 per cent burns developed edema of the vocal cords with mild hoarseness. They improved and recovered without intubation. The facility was prepared for the mass casualty event; having just completed a mass casualty drill several days earlier. Twenty-six beds were made available in 50 minutes for anticipated casualties. Fifteen physicians reported immediately to the trauma resuscitation area to assist in initial stabilization. The event occurred at shift change; thus, adequate support

  20. An Air Mass Based Approach to the Establishment of Spring Season Synoptic Characteristics in the Northeast United States

    NASA Astrophysics Data System (ADS)

    Zander, R.; Messina, A.; Godek, M. L.

    2012-12-01

    The spring season is indicative of marked meteorological, ecological, and biological changes across the Northeast United States. The onset of spring coincides with distinct meteorological phenomena including an increase in severe weather events and snow meltwaters that can cause localized flooding and other costly damages. Increasing and variable springtime temperatures also influence Northeast tourist operations and agricultural productivity. Even with the vested interest of industry in the season and public awareness of the dynamic characteristics of spring, the definition of spring remains somewhat arbitrary. The primary goal of this research is to obtain a synoptic meteorological definition of the spring season through an assessment of air mass frequency over the past 60 years. A secondary goal examines the validity of recent speculations that the onset and termination of spring has changed in recent decades, particularly since 1975. The Spatial Synoptic Classification is utilized to define daily air masses over the region. Annual and seasonal baseline frequencies are identified and their differences are acquired to characterize the season. Seasonal frequency departures of the early and late segments of the period of record around 1975 are calculated and examined for practical and statistical significance. The daily boundaries of early and late spring are then isolated and frequencies are obtained for these periods. Boundary frequencies are assessed across the period of record to identify important changes in the season's initiation and termination through time. Results indicate that the Northeast spring season is dominated by dry air masses, mainly the Dry Moderate and Dry Polar types. Significant differences in seasonal air mass frequency are also observed through time. Prior to 1975, higher frequencies of polar air mass types are detected while after 1975 there is an increase in the frequencies of both moderate and tropical types. This finding is also

  1. Evidence of rapid production of organic acids in an urban air mass

    NASA Astrophysics Data System (ADS)

    Veres, Patrick R.; Roberts, James M.; Cochran, Anthony K.; Gilman, Jessica B.; Kuster, William C.; Holloway, John S.; Graus, Martin; Flynn, James; Lefer, Barry; Warneke, Carsten; de Gouw, Joost

    2011-09-01

    Gas-phase acids (nitric, formic, acrylic, methacrylic, propionic, and pyruvic/butryic acid) were measured using negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS) in Pasadena, CA as part of the CalNex 2010 (Research at the Nexus of Air Quality and Climate Change) study in May-June 2010. Organic acid concentrations ranged from a few parts per trillion by volume (pptv) to several parts per billion by volume (ppbv), with the largest concentrations observed for formic and propionic acids. Photochemically processed urban emissions transported from Los Angeles were frequently sampled during the day. Analysis of transported emissions demonstrates a strong correlation of organic acid concentrations with both nitric acid and odd oxygen (Ox = O3 + NO2) showing that the organic acids are photochemically and rapidly produced from urban emissions.

  2. Progress Toward a Global, EOS-Era Aerosol Air Mass Type Climatology

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.

    2012-01-01

    The MISR and MODIS instruments aboard the NASA Earth Observing System's Terra Satellite have been collecting data containing information about the state of Earth's atmosphere and surface for over eleven years. Data from these instruments have been used to develop a global, monthly climatology of aerosol amount that is widely used as a constraint on climate models, including those used for the 2007 IPCC assessment report. The next frontier in assessing aerosol radiative forcing of climate is aerosol type, and in particular, the absorption properties of major aerosol air masses. This presentation will focus on the prospects for constraining aerosol type globally, and the steps we are taking to apply a combination of satellite and suborbital data to this challenge.

  3. The influence of polarization on box air mass factors for UV/vis nadir satellite observations

    NASA Astrophysics Data System (ADS)

    Hilboll, Andreas; Richter, Andreas; Rozanov, Vladimir V.; Burrows, John P.

    2015-04-01

    Tropospheric abundances of pollutant trace gases like, e.g., NO2, are often derived by applying the differential optical absorption spectroscopy (DOAS) method to space-borne measurements of back-scattered and reflected solar radiation. The resulting quantity, the slant column density (SCD), subsequently has to be converted to more easily interpretable vertical column densities by means of the so-called box air mass factor (BAMF). The BAMF describes the ratio of SCD and VCD within one atmospheric layer and is calculated by a radiative transfer model. Current operational and scientific data products of satellite-derived trace gas VCDs do not include the effect of polarization in their radiative transfer models. However, the various scattering processes in the atmosphere do lead to a distinctive polarization pattern of the observed Earthshine spectra. This study investigates the influence of these polarization patterns on box air mass factors for satellite nadir DOAS measurements of NO2 in the UV/vis wavelength region. NO2 BAMFs have been simulated for a multitude of viewing geometries, surface albedos, and surface altitudes, using the radiative transfer model SCIATRAN. The results show a potentially large influence of polarization on the BAMF, which can reach 10% and more close to the surface. A simple correction for this effect seems not to be feasible, as it strongly depends on the specific measurement scenario and can lead to both high and low biases of the resulting NO2 VCD. We therefore conclude that all data products of NO2 VCDs derived from space-borne DOAS measurements should include polarization effects in their radiative transfer model calculations, or at least include the errors introduced by using linear models in their uncertainty estimates.

  4. Identification of aerosol types over an urban site based on air-mass trajectory classification

    NASA Astrophysics Data System (ADS)

    Pawar, G. V.; Devara, P. C. S.; Aher, G. R.

    2015-10-01

    Columnar aerosol properties retrieved from MICROTOPS II Sun Photometer measurements during 2010-2013 over Pune (18°32‧N; 73°49‧E, 559 m amsl), a tropical urban station in India, are analyzed to identify aerosol types in the atmospheric column. Identification/classification is carried out on the basis of dominant airflow patterns, and the method of discrimination of aerosol types on the basis of relation between aerosol optical depth (AOD500 nm) and Ångström exponent (AE, α). Five potential advection pathways viz., NW/N, SW/S, N, SE/E and L have been identified over the observing site by employing the NOAA-HYSPLIT air mass back trajectory analysis. Based on AE against AOD500 nm scatter plot and advection pathways followed five major aerosol types viz., continental average (CA), marine continental average (MCA), urban/industrial and biomass burning (UB), desert dust (DD) and indeterminate or mixed type (MT) have been identified. In winter, sector SE/E, a representative of air masses traversed over Bay of Bengal and Eastern continental Indian region has relatively small AOD (τpλ = 0.43 ± 0.13) and high AE (α = 1.19 ± 0.15). These values imply the presence of accumulation/sub-micron size anthropogenic aerosols. During pre-monsoon, aerosols from the NW/N sector have high AOD (τpλ = 0.61 ± 0.21), and low AE (α = 0.54 ± 0.14) indicating an increase in the loading of coarse-mode particles over Pune. Dominance of UB type in winter season for all the years (i.e. 2010-2013) may be attributed to both local/transported aerosols. During pre-monsoon seasons, MT is the dominant aerosol type followed by UB and DD, while the background aerosols are insignificant.

  5. AUTOMATED DECONVOLUTION OF COMPOSITE MASS SPECTRA OBTAINED WITH AN OPEN-AIR IONIZATIONS SOURCE BASED ON EXACT MASSES AND RELATIVE ISOTIPIC ABUNDANCES

    EPA Science Inventory

    Chemicals dispersed by accidental, deliberate, or weather-related events must be rapidly identified to assess health risks. Mass spectra from high levels of analytes obtained using rapid, open-air ionization by a Direct Analysis in Real Time (DART®) ion source often contain

  6. Bioaccumulation Potential Of Air Contaminants: Combining Biological Allometry, Chemical Equilibrium And Mass-Balances To Predict Accumulation Of Air Pollutants In Various Mammals

    SciTech Connect

    Veltman, Karin; McKone, Thomas E.; Huijbregts, Mark A.J.; Hendriks, A. Jan

    2009-03-01

    In the present study we develop and test a uniform model intended for single compartment analysis in the context of human and environmental risk assessment of airborne contaminants. The new aspects of the model are the integration of biological allometry with fugacity-based mass-balance theory to describe exchange of contaminants with air. The developed model is applicable to various mammalian species and a range of chemicals, while requiring few and typically well-known input parameters, such as the adult mass and composition of the species, and the octanol-water and air-water partition coefficient of the chemical. Accumulation of organic chemicals is typically considered to be a function of the chemical affinity forlipid components in tissues. Here, we use a generic description of chemical affinity for neutral and polar lipids and proteins to estimate blood-air partition coefficients (Kba) and tissue-air partition coefficients (Kta) for various mammals. This provides a more accurate prediction of blood-air partition coefficients, as proteins make up a large fraction of total blood components. The results show that 75percent of the modeled inhalation and exhalation rate constants are within a factor of 2 from independent empirical values for humans, rats and mice, and 87percent of the predicted blood-air partition coefficients are within a factor of 5 from empirical data. At steady-state, the bioaccumulation potential of air pollutants is shown to be mainly a function of the tissue-air partition coefficient and the biotransformation capacity of the species and depends weakly on the ventilation rate and the cardiac output of mammals.

  7. Right paracardiac mass due to organized pericardial hematoma around retained epicardial pacing wires following aortic valve replacement.

    PubMed

    Kapoor, Aditya; Syal, Sanjiv; Gupta, Nirmal; Gupta, Archana

    2011-07-01

    The use of temporary epicardial pacing wires during cardiac surgery is a routine procedure and has been associated with low morbidity. We describe a rare case of right paracardiac mass due to organized pericardial hematoma with right atrial compression around the epicardial pacing wires left in-situ, presenting three months following aortic valve replacement surgery. The case highlights the fact that such delayed complications can rarely occur around retained epicardial pacing wires following open heart surgery especially in patients on oral anticoagulants. The clinician should be alert to such an occurrence and during follow-up echocardiography always pay attention not only to the valve and ventricular function, but also to the pericardial and extra-pericardial space. PMID:21362730

  8. Enantiomeric signatures of organochlorine pesticides in Asian, trans-Pacific, and western U.S. air masses.

    PubMed

    Genualdi, Susan A; Simonich, Staci L Massey; Primbs, Toby K; Bidleman, Terry F; Jantunen, Liisa M; Ryoo, Keon-Sang; Zhu, Tong

    2009-04-15

    The enantiomeric signatures of organochlorine pesticides were measured in air masses from Okinawa, Japan and three remote locations in the Pacific Northwestern United States: Cheeka Peak Observatory (CPO), a marine boundary layer site on the Olympic Peninsula of Washington at 500 m above sea level (m.a.s.l); Mary's Peak Observatory (MPO), a site at 1250 m.a.s.l in Oregon's Coast range; and Mt. Bachelor Observatory (MBO), a site at 2763 m.a.s.l in Oregon's Cascade range. The enantiomeric signatures of composite soil samples, collected from China, South Korea, and the western U.S. were also measured. The data from chiral analysis was expressed asthe enantiomeric fraction, defined as (+) enantiomer/(sum of the (+) and (-) enantiomers), where a racemic composition has EF = 0.5. Racemic alpha-hexachlorocyclohexane (alpha-HCH) was measured in Asian air masses at Okinawa and in Chinese and South Korean soils. Nonracemic alpha-HCH (EF = 0.528 +/- 0.0048) was measured in regional air masses at CPO, and may reflect volatilization from the Pacific Ocean and regional soils. However, during trans-Pacific transport events at CPO, the alpha-HCH EFs were significantly more racemic (EF = 0.513 +/- 0.0003, p < 0.001). Racemic alpha-HCH was consistently measured at MPO and MBO in trans-Pacific air masses that had spent considerable time in the free troposphere. The alpha-HCH EFs in CPO, MPO, and MBO air masses were negatively correlated (p = 0.0017) with the amount of time the air mass spent above the boundary layer, along the 10-day back air mass trajectory, prior to being sampled. This suggests that, on the West coast of the U.S., the alpha-HCH in the free troposphere is racemic. Racemic signatures of cis- and trans-chlordane were measured in air masses at all four air sampling sites, suggesting that Asian and U.S. urban areas continue to be sources of chlordane that has not yet been biotransformed. PMID:19475954

  9. Variation in airborne 137Cs peak levels with altitude from high-altitude locations across Europe after the arrival of Fukushima-labeled air masses

    NASA Astrophysics Data System (ADS)

    Masson, Olivier; Bieringer, Jacqueline; Dalheimer, Axel; Estier, Sybille; Evrard, Olivier; Penev, Ilia; Ringer, Wolfgang; Schlosser, Clemens; Steinkopff, Thomas; Tositti, Laura; de Vismes-Ott, Anne

    2015-04-01

    During the Fukushima Daiichi nuclear power plant (FDNPP) accident, a dozen of high-altitude aerosol sampling stations, located between 850 and 3,454 m above sea level (a.s.l.), provided airborne activity levels across Europe (Fig. 1). This represents at most 5% of the total number of aerosol sampling locations that delivered airborne activity levels (at least one result) in Europe, in connection with this nuclear accident. High altitude stations are typically equipped with a high volume sampler that collects aerosols on filters. The Fukushima-labeled air mass arrival and the peak of airborne cesium-137 (137Cs) activity levels were registered in Europe at different dates depending on the location, with differences up to a factor of six on a regional scale. Besides this statement related to lowland areas, we have compared the maximum airborne levels registered at high-altitude European locations (850 m < altitudes < 3450 m) with what was observed at the closest lowland location. The vertical distribution of 137Cs peak level was not uniform even after a long travel time/distance from Japan. This being true at least in the atmospheric boundary layer and in the lower free troposphere. Moreover the relation '137Csmax vs. altitude' shows a decreasing trend (Fig. 2). Results and discussion : Comparison of 137Cs and 7Be levels shows simultaneous increases at least when the 137Cs airborne level rose for the first time (Fig. 3). Zugspitze and Jungfraujoch stations attest of a time shift between 7Be and 137Cs peak that can be due to the particular dynamic of air movements at such high altitudes. After the 137Cs peak value, the plume concentration decreased whatever the 7Be level. Due to the cosmogenic origin of 7Be, its increase in the ground-level air is usually associated with downwind air movements, i.e. stratospheric air intrusions or at least air from high-tropospheric levels, into lower atmospheric layers. This means that Fukushima-labeled air masses registered at ground

  10. Association between air pollution and daily mortality and hospital admission due to ischaemic heart diseases in Hong Kong

    NASA Astrophysics Data System (ADS)

    Tam, Wilson Wai San; Wong, Tze Wai; Wong, Andromeda H. S.

    2015-11-01

    Ischaemic heart disease (IHD) is one of the leading causes of death worldwide. The effects of air pollution on IHD mortalities have been widely reported. Fewer studies focus on IHD morbidities and PM2.5, especially in Asia. To explore the associations between short-term exposure to air pollution and morbidities and mortalities from IHD, we conducted a time series study using a generalized additive model that regressed the daily numbers of IHD mortalities and hospital admissions on daily mean concentrations of the following air pollutants: nitrogen dioxide (NO2), particulate matter with an aerodynamic diameter less than 10 μm (PM10), particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5), ozone (O3), and sulfur dioxide (SO2). The relative risks (RR) of IHD deaths and hospital admissions per 10 μg/m3 increase in the concentration of each air pollutant were derived in single pollutant models. Multipollutant models were also constructed to estimate their RRs controlling for other pollutants. Significant RRs were observed for all five air pollutants, ranging from 1.008 to 1.032 per 10 μg/m3 increase in air pollutant concentrations for IHD mortality and from 1.006 to 1.021 per 10 μg/m3 for hospital admissions for IHD. In the multipollutant model, only NO2 remained significant for IHD mortality while SO2 and PM2.5 was significantly associated with hospital admissions. This study provides additional evidence that mortalities and hospital admissions for IHD are significantly associated with air pollution. However, we cannot attribute these health effects to a specific air pollutant, owing to high collinearity between some air pollutants.

  11. Study Case of Air-Mass Modification over Poland and Romania Observed by the Means of Multiwavelength Raman Depolarization Lidars

    NASA Astrophysics Data System (ADS)

    Costa-Surós, Montserrat; Janicka, Lucja; Stachlewska, Iwona S.; Nemuc, Anca; Talianu, Camelia; Heese, Birgit; Engelmann, Ronny

    2016-06-01

    An air-mass modification, on its way from Poland to Romania, observed between 19-21 July 2014 is discussed. The air-mass was investigated using data of two multi-wavelength lidars capable of performing regular elastic, depolarization and Raman measurements in Warsaw, Poland, and in Magurele, Romania. The analysis was focused on evaluating optical properties of aerosol in order to search for similarities and differences in the vertical profiles describing the atmospheric layers above the two stations within given period.

  12. Large-scale transport of a CO-enhanced air mass from Europe to the Middle East

    NASA Technical Reports Server (NTRS)

    Connors, V. S.; Miles, T.; Reichle, H. G., Jr.

    1989-01-01

    On November 14, 1981, the shuttle-borne Measurement of Air Pollution from Satellites (MAPS) experiment observed a carbon monoxide (CO) enhanced air mass in the middle troposphere over the Middle East. The primary source of this polluted air was estimated by constructing adiabatic isentropic trajectories backwards from the MAPS measurement location over a 36 h period. The isentropic diagnostics indicate that CO-enhanced air was transported southeastward over the Mediterranean from an organized synoptic-scale weather regime, albeit of moderate intensity, influencing central Europe on November 12. Examination of the evolving synoptic scale vertical velocity and precipitation patterns during this period, in conjuction with Meteosat visible, infrared, and water vapor imagery, suggests that the presence of this disturbed weather system over Europe may have created upward transport of CO-enhanced air between the boundary-layer and midtropospheric levels, and subsequent entrainment in the large-scale northwesterly jet stream flow over Europe and the Mediterranean.

  13. Characterizing Air Masses in the Lower Troposphere (< 2 km) during the 2011 Student Airborne Program (SARP) Mission in Southern California

    NASA Astrophysics Data System (ADS)

    Lee, H.; Elder, C.; Kauffman, E. J.; Weathers, E.; Thomas, E.; Johnson, E.; Turrentine, H.; Saad, K.; Nighelli, K.; Burns, M.; Heath, N.; Shetter, R. E.; Schaller, E.; Webster, A.; Buzay, E.; Peterson, J.; Simpson, I. J.; Rowland, F. S.; Blake, D. R.

    2011-12-01

    During the NASA Student Airborne Program (SARP) mission, high frequency whole air sampling during a missed-approach to Los Angeles International airport (LAX) provided air mass signatures collected in close proximity to their urban and oceanic sources. Each whole air sample was analyzed for 80 halocarbons, hydrocarbons and organic nitrates. Unlike other airborne missions, high frequency whole air sampling of about 70 samples collected over a 20 minute period (15 second fill per sample) during a 150 km flight path at low altitude (< 2 km) provided a more detailed profile of the Los Angeles air shed than has been previously accomplished. Correlations between CH3I, CHBr3, and MeONO2 (marine tracers) versus C2Cl4 and HCFC-22 (anthropogenic tracers) were used to distinguish between purely marine air and air influenced by emissions from Los Angeles (Figure 1). Of the 80 C1-C10 volatile organic compounds that were measured, 60 were elevated in air from the Los Angeles air shed. These included C1-C10 alkanes, C6-C8 aromatics, C2-C3 alkenes, halons, HCFCs, HFCs, CH3CCl3, chlorinated solvents (e.g., C2Cl4, CHCl3, CH2Cl2), and organic nitrates. Marine species emitted in this region of the Pacific were found to include MeONO2, EtONO2, CH2Br2, CHBr3, CH3I and DMS. Note that the C3 organic nitrates were not enhanced in the marine influenced air, and instead they are attributed to urban photochemistry. Overall, high-frequency and low-altitude whole air sampling during the LAX missed-approach clearly distinguished urban and oceanic sources and allowed a detailed chemical signature for Los Angeles air to be determined.

  14. Identification of water-soluble polar organics in air and vehicular emitted particulate matter using ultrahigh resolution mass spectrometry and Capillary electrophoresis - mass spectrometry.

    NASA Astrophysics Data System (ADS)

    Schmitt-Kopplin, P.; Yassine, M.; Gebefugi, I.; Hertkorn, N.; Dabek-Zlotorzynska, E.

    2009-04-01

    The effects of aerosols on human health, atmospheric chemistry, and climate are among the central topics in current environmental health research. Detailed and accurate measurements of the chemical composition of air particulate matter (PM) represent a challenging analytical task. Minute sample amounts are usually composed of several main constituents and hundreds of minor and trace constituents. Moreover, the composition of individual particles can be fairly uniform or very different (internally or externally mixed aerosols), depending on their origin and atmospheric aging processes (coagulation, condensation / evaporation, chemical reaction). The aim of the presentation was the characterization of the organic matter (OM) fraction of environmental aerosols which is not accessible by GC-methods, either because of their high molecular weight, their polarity or due to thermal instability. We also describe the main chemical characteristics of complexe oligomeric organic fraction extracted from different aerosols collected in urban and rural area in Germany and Canada. Mass spectrometry (MS) became an essential tool used by many prominent leaders of the biological research community and the importance of MS to the future of biological research is now clearly evident as in the fields of Proteomics and Metabolomics. Especially Fourier Transform Ion Cyclotron Mass Spectrometry (ICR-FT/MS) is an ultrahigh resolution MS that allows new approach in the analysis of complex mixtures. The mass resolution (< 200 ppb) allowed assigning the elemental composition (C, H, O, N, S…) to each of the obtained mass peaks and thus already a description of the mixture in terms of molecular composition. This possibility is used by the authors together with a high resolution separation method of charged compounds: capillary electrophoresis. A CE-ESI-MS method using an ammonium acetate based background electrolyte (pH 4.7) was developed for the determination of isomeric benzoic acids in

  15. Mass flow of antibiotics in a wastewater treatment plant focusing on removal variations due to operational parameters.

    PubMed

    Marx, Conrad; Günther, Norbert; Schubert, Sara; Oertel, Reinhard; Ahnert, Markus; Krebs, Peter; Kuehn, Volker

    2015-12-15

    Wastewater treatment plants (WWTPs) are not designed to purposefully eliminate antibiotics and therefore many previous investigations have been carried out to assess their fate in biological wastewater treatment processes. In order to consolidate previous findings regarding influencing factors like the solid and hydraulic retention time an intensive monitoring was carried out in a municipal WWTP in Germany. Over a period of 12months daily samples were taken from the in- and effluent as well as diverse sludge streams. The 14 selected antibiotics and one metabolite cover the following classes: cephalosporins, diaminopyrimidines, fluoroquinolones, lincosamide, macrolides, penicillins, sulfonamides and tetracyclines. Out of the 15 investigated substances, the removal of only clindamycin and ciprofloxacin show significant correlations to SRT, temperature, HRT and nitrogen removal. The dependency of clindamycin's removal could be related to the significant negative removal (i.e. production) of clindamycin in the treatment process and was corrected using the human metabolite clindamycin-sulfoxide. The average elimination was adjusted from -225% to 3% which suggests that clindamycin can be considered as an inert substance during the wastewater treatment process. Based on the presented data, the mass flow analysis revealed that macrolides, clindamycin/clindamycin-sulfoxide and trimethoprim were mainly released with the effluent, while penicillins, cephalosporins as well as sulfamethoxazole were partly degraded in the studied WWTP. Furthermore, levofloxacin and ciprofloxacin are the only antibiotics under investigation with a significant mass fraction bound to primary, excess and digested sludge. Nevertheless, the sludge concentrations are highly inconsistent which leads to questionable results. It remains unclear whether the inconsistencies are due to insufficiencies in sampling and/or analytical determination or if the fluctuations can be considered reasonable for

  16. Long-Term Exposure to Ambient Air Pollution and Mortality Due to Cardiovascular Disease and Cerebrovascular Disease in Shenyang, China

    PubMed Central

    Sun, Baijun; Zhang, Liwen; Chen, Xi; Ma, Nannan; Yu, Fei; Guo, Huimin; Huang, Hui; Lee, Yungling Leo; Tang, Naijun; Chen, Jie

    2011-01-01

    Background The relationship between ambient air pollution exposure and mortality of cardiovascular and cerebrovascular diseases in human is controversial, and there is little information about how exposures to ambient air pollution contribution to the mortality of cardiovascular and cerebrovascular diseases among Chinese. The aim of the present study was to examine whether exposure to ambient-air pollution increases the risk for cardiovascular and cerebrovascular disease. Methodology/Principal Findings We conducted a retrospective cohort study among humans to examine the association between compound-air pollutants [particulate matter <10 µm in aerodynamic diameter (PM10), sulfur dioxide (SO2) and nitrogen dioxide (NO2)] and mortality in Shenyang, China, using 12 years of data (1998–2009). Also, stratified analysis by sex, age, education, and income was conducted for cardiovascular and cerebrovascular mortality. The results showed that an increase of 10 µg/m3 in a year average concentration of PM10 corresponds to 55% increase in the risk of a death cardiovascular disease (hazard ratio [HR], 1.55; 95% confidence interval [CI], 1.51 to 1.60) and 49% increase in cerebrovascular disease (HR, 1.49; 95% CI, 1.45 to 1.53), respectively. The corresponding figures of adjusted HR (95%CI) for a 10 µg/m3 increase in NO2 was 2.46 (2.31 to 2.63) for cardiovascular mortality and 2.44 (2.27 to 2.62) for cerebrovascular mortality, respectively. The effects of air pollution were more evident in female that in male, and nonsmokers and residents with BMI<18.5 were more vulnerable to outdoor air pollution. Conclusion/Significance Long-term exposure to ambient air pollution is associated with the death of cardiovascular and cerebrovascular diseases among Chinese populations. PMID:21695220

  17. Artificial neural networks forecasting of PM2.5 pollution using air mass trajectory based geographic model and wavelet transformation

    NASA Astrophysics Data System (ADS)

    Feng, Xiao; Li, Qi; Zhu, Yajie; Hou, Junxiong; Jin, Lingyan; Wang, Jingjie

    2015-04-01

    In the paper a novel hybrid model combining air mass trajectory analysis and wavelet transformation to improve the artificial neural network (ANN) forecast accuracy of daily average concentrations of PM2.5 two days in advance is presented. The model was developed from 13 different air pollution monitoring stations in Beijing, Tianjin, and Hebei province (Jing-Jin-Ji area). The air mass trajectory was used to recognize distinct corridors for transport of "dirty" air and "clean" air to selected stations. With each corridor, a triangular station net was constructed based on air mass trajectories and the distances between neighboring sites. Wind speed and direction were also considered as parameters in calculating this trajectory based air pollution indicator value. Moreover, the original time series of PM2.5 concentration was decomposed by wavelet transformation into a few sub-series with lower variability. The prediction strategy applied to each of them and then summed up the individual prediction results. Daily meteorological forecast variables as well as the respective pollutant predictors were used as input to a multi-layer perceptron (MLP) type of back-propagation neural network. The experimental verification of the proposed model was conducted over a period of more than one year (between September 2013 and October 2014). It is found that the trajectory based geographic model and wavelet transformation can be effective tools to improve the PM2.5 forecasting accuracy. The root mean squared error (RMSE) of the hybrid model can be reduced, on the average, by up to 40 percent. Particularly, the high PM2.5 days are almost anticipated by using wavelet decomposition and the detection rate (DR) for a given alert threshold of hybrid model can reach 90% on average. This approach shows the potential to be applied in other countries' air quality forecasting systems.

  18. Structural characterization of p53 isoforms due to the polymorphism at codon 72 by mass spectrometry and circular dichroism.

    PubMed

    Naldi, Marina; Pistolozzi, Marco; Bertucci, Carlo; De Simone, Angela; Altilia, Serena; Pierini, Michela; Franceschi, Claudio; Salvioli, Stefano; Andrisano, Vincenza

    2010-10-10

    different, thus allowing us to exclude that the observed biological differences can be due to a different conformation of the two isoforms introduced by this polymorphism. Furthermore, these studies establish a mass spectrometry method to identify the two isoforms that can be useful for future interactome studies and cancer drug discovery. PMID:20427142

  19. Dust and Pollution Aerosol Air Mass Mapping from Satellite Multi-angle Imaging

    NASA Astrophysics Data System (ADS)

    Kahn, R. A.; Nelson, D. L.; Yau, K. S.; Martonchik, J.; Diner, D. J.; Gaitley, B. J.; Russell, P.; Livingston, J.; Redemann, J.; Quinn, P. R.; Clarke, A. R.; Howell, S.; McNaughton, C.; Reid, J.; Holben, B.; Wendisch, M.; Petzold, A.

    2006-12-01

    One objective of the NASA Earth Observing System's Multi-angle Imaging SpectroRadiometer (MISR) is to map aerosol air mass types, based on retrieved column-average particle microphysical properties. Early results demonstrated the ability to distinguish three-to-five bins over the 0.1 to 2.5 micron aerosol size range, about two-to-four groupings of single-scattering albedo, and to separate spherical from randomly oriented non- spherical particles, under good but not ideal viewing conditions. These results relied heavily on the MISR Research Aerosol Retrieval algorithm, which allows flexibility in choosing retrieval patch size and location, component aerosol properties and mixtures, and mixture acceptance criteria, compared to early versions of the MISR Standard algorithm, designed to routinely process the entire global data set. Early mid-visible column aerosol optical depth results were validated against surface-based sun photometer measurements. The corresponding particle property results appeared qualitatively promising, but formal validation requires quantitative constraints on component particle properties and mixtures in a range of natural settings, available mainly from the combination of height-resolved and total column data collected by surface and airborne instruments during field campaigns. This presentation will highlight the latest detailed, multi-platform case studies, as well as MISR regional mapping, of smoke, Saharan dust, and mixtures of pollution aerosol and desert dust collected during the INTEX, SAMUM, and UAE-2 campaigns, respectively. The broader implications of these results for global, and especially regional, aerosol climate and air quality studies will also be discussed. This work is performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  20. Optimization of solar cells for air mass zero operation and a study of solar cells at high temperatures, phase 3

    NASA Technical Reports Server (NTRS)

    Blakeslee, A. E.; Hovel, H. J.; Woodall, J. M.

    1977-01-01

    The etch-back epitaxy process is described for producing thin, graded composition GaAlAs layers. The palladium-aluminum contact system is discussed along with its associated problems. Recent solar cell results under simulated air mass zero light and at elevated temperatures are reported and the growth of thin polycrystalline GaAs films on foreign substrates is developed.

  1. An objective classification system of air mass types for Szeged, Hungary, with special attention to plant pollen levels.

    PubMed

    Makra, László; Juhász, Miklós; Mika, János; Bartzokas, Aristides; Béczi, Rita; Sümeghy, Zoltán

    2006-07-01

    This paper discusses the characteristic air mass types over the Carpathian Basin in relation to plant pollen levels over annual pollination periods. Based on the European Centre for Medium-Range Weather Forecasts dataset, daily sea-level pressure fields analysed at 00 UTC were prepared for each air mass type (cluster) in order to relate sea-level pressure patterns to pollen levels in Szeged, Hungary. The database comprises daily values of 12 meteorological parameters and daily pollen concentrations of 24 species for their pollination periods from 1997 to 2001. Characteristic air mass types were objectively defined via factor analysis and cluster analysis. According to the results, nine air mass types (clusters) were detected for pollination periods of the year corresponding to pollen levels that appear with higher concentration when irradiance is moderate while wind speed is moderate or high. This is the case when an anticyclone prevails in the region west of the Carpathian Basin and when Hungary is under the influence of zonal currents (wind speed is high). The sea level pressure systems associated with low pollen concentrations are mostly similar to those connected to higher pollen concentrations, and arise when wind speed is low or moderate. Low pollen levels occur when an anticyclone prevails in the region west of the Carpathian Basin, as well as when an anticyclone covers the region with Hungary at its centre. Hence, anticyclonic or anticyclonic ridge weather situations seem to be relevant in classifying pollen levels. PMID:16575583

  2. Background NO/sub x/ mixing ratios in air masses over the North Atlantic ocean

    SciTech Connect

    Helas, G.; Warneck, P.

    1981-08-20

    A chemiluminescence analyzer was used to measure NO/sub x/ mixing ratios at the west coast of Ireland. Two measurement modes allowed the determination of NO and NO/sub x/ = NO+NO/sub 2/. In a third mode using a molybdenum converter, higher signals were observed than was in the second mode indicating that nitrogen compounds other than NO+NO/sub 2/ are registered. They are denoted 'excess NO/sub x/'. The average NO/sub 2/ mixing ratio for a week period was 101 +- 87 pptv. In pure marine air masses identified by means of trajectory calculations, the NO/sub 2/ mixing ratios were lower and exhibited in addition a diurnal variation with nighttime values of 37 +- 6 pptv and average values of 87 +- 47 pptv. Possible origins of the diurnal variation are discussed. For such conditions, the NO mixing ratio generally was unmeasurably small, certainly less than 10 pptv. The excess NO/sub x/ is also higher during the day compared with nighttime values of about 70 pptv. Further studies are required to identify the compounds involved.

  3. Variations of the glacio-marine air mass front in West Greenland through water vapor isotopes

    NASA Astrophysics Data System (ADS)

    Kopec, B. G.; Lauder, A. M.; Posmentier, E. S.; Feng, X.

    2012-12-01

    While the isotopic distribution of precipitation has been widely used for research in hydrology, paleoclimatology, and ecology for decades, intensive isotopic studies of atmospheric water vapor has only recently been made possible by spectral-based technology. New instrumentation based on this technology opens up many opportunities to investigate short-term atmospheric dynamics involving the water cycle and moisture transport. We deployed a Los Gatos Water Vapor Isotope Analyzer (WVIA) at Kangerlussuaq, Greenland from July 21 to August 15, and measured the water vapor concentration and its isotopic ratios continuously at 10s intervals. A Danish Meteorological Institute site is located about 1 km from the site of the deployment, and meteorological data is collected at 30 min intervals. During the observation period, the vapor concentration of the ambient air ranges from 5608.4 to 11189.4 ppm; dD and d18O range from -254.5 to -177.7 ‰ and -34.2 to -23.2 ‰, respectively. The vapor content (dew point) and the isotopic ratios are both strongly controlled by the wind direction. The easterly winds are associated with dry, isotopically depleted air masses formed over the glacier, while westerly winds are associated with moist and isotopically enriched air masses from the marine/fjord surface. This region typically experiences katabatic winds off of the ice sheet to the east. However, during some afternoons, the wind shifts 180 degrees, blowing off the fjord to the west. This wind switch marks the onset of a sea breeze, and significant isotopic enrichment results. Enrichment in deuterium is up to 60 ‰ with a mean of 15‰, and oxygen-18 is enriched by 3‰ on average and up to 8 ‰. Other afternoons have no change in wind, and only small changes in humidity and vapor isotopic ratios. The humidity and isotopic variations suggest the local atmosphere circulation is dominated by relatively high-pressure systems above the cold glaciers and cool sea surface, and diurnal

  4. New Directions: Questions surrounding suspended particle mass used as a surrogate for air quality and for regulatory control of ambient urban air pollution

    NASA Astrophysics Data System (ADS)

    Hoare, John L.

    2014-07-01

    The original choice of particulate matter mass (PM) as a realistic surrogate for gross air pollution has gradually evolved into routine use nowadays of epidemiologically-based estimates of the monetary and other benefits expected from regulating urban air quality. Unfortunately, the statistical associations facilitating such calculations usually are based on single indices of air pollution whereas the health effects themselves are more broadly based causally. For this and other reasons the economic benefits of control tend to be exaggerated. Primarily because of their assumed inherently inferior respirability, particles ≥10 μm are generally excluded from such considerations. Where the particles themselves are chemically heterogeneous, as in an urban context, this may be inappropriate. Clearly all air-borne particles, whether coarse or fine, are susceptible to inhalation. Hence, the possibility exists for any adhering potentially harmful semi-volatile substances to be subsequently de-sorbed in vivo thereby facilitating their transport deeper into the lungs. Consequently, this alone may be a sufficient reason for including rather than rejecting during air quality monitoring the relatively coarse 10-100 μm particle fraction, ideally in conjunction with routine estimation of the gaseous co-pollutants thereby facilitating a multi-pollutant approach apropos regulation.

  5. The impact of mass flow and masking on the pressure drop of air filter in heavy-duty diesel engine

    NASA Astrophysics Data System (ADS)

    Hoseeinzadeh, Sepideh; Gorji-Bandpy, Mofid

    2012-04-01

    This paper presents a computational fluid dynamics (CFD) calculation approach to predict and evaluate the impact of the mass-flow inlet on the pressure drop of turbocharger`s air filtfer in heavy-duty diesel engine. The numerical computations were carried out using a commercial CFD program whereas the inlet area of the air filter consisted of several holes connected to a channel. After entering through the channel, the air passes among the holes and enters the air filter. The effect of masking holes and hydraulic diameter is studied and investigated on pressure drop. The results indicate that pressure drop increase with decreasing of hydraulic diameter and masking of the holes has considerable affect on the pressure drop.

  6. Cluster Analysis of the Organic Peaks in Bulk Mass Spectra Obtained During the 2002 New England Air Quality Study with an Aerodyne Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Marcolli, C.; Canagaratna, M. R.; Worsnop, D. R.; Bahreini, R.; de Gouw, J. A.; Warneke, C.; Goldan, P. D.; Kuster, W. C.; Williams, E. J.; Lerner, B. M.; Roberts, J. M.; Meagher, J. F.; Fehsenfeld, F. C.; Marchewka, M.; Bertman, S. B.; Middlebrook, A. M.

    2006-12-01

    We applied hierarchical cluster analysis to an Aerodyne aerosol mass spectrometer (AMS) bulk mass spectral dataset collected aboard the NOAA research vessel R. H. Brown during the 2002 New England Air Quality Study off the east coast of the United States. Emphasizing the organic peaks, the cluster analysis yielded a series of categories that are distinguishable with respect to their mass spectra and their occurrence as a function of time. The differences between the categories mainly arise from relative intensity changes rather than from the presence or absence of specific peaks. The most frequent category exhibits a strong signal at m/z 44 and represents oxidized organic matter probably originating from both anthropogenic as well as biogenic sources. On the basis of spectral and trace gas correlations, the second most common category with strong signals at m/z 29, 43, and 44 contains contributions from isoprene oxidation products. The third through the fifth most common categories have peak patterns characteristic of monoterpene oxidation products and were most frequently observed when air masses from monoterpene rich regions were sampled. Taken together, the second through the fifth most common categories represent on average 17% of the total organic mass that stems likely from biogenic sources during the ship's cruise. These numbers have to be viewed as lower limits since the most common category was attributed to anthropogenic sources for this calculation. The cluster analysis was also very effective in identifying a few contaminated mass spectra that were not removed during pre-processing. This study demonstrates that hierarchical clustering is a useful tool to analyze the complex patterns of the organic peaks in bulk aerosol mass spectra from a field study.

  7. Wireless Tri-Axial Trunk Accelerometry Detects Deviations in Dynamic Center of Mass Motion Due to Running-Induced Fatigue

    PubMed Central

    2015-01-01

    Small wireless trunk accelerometers have become a popular approach to unobtrusively quantify human locomotion and provide insights into both gait rehabilitation and sports performance. However, limited evidence exists as to which trunk accelerometry measures are suitable for the purpose of detecting movement compensations while running, and specifically in response to fatigue. The aim of this study was therefore to detect deviations in the dynamic center of mass (CoM) motion due to running-induced fatigue using tri-axial trunk accelerometry. Twenty runners aged 18–25 years completed an indoor treadmill running protocol to volitional exhaustion at speeds equivalent to their 3.2 km time trial performance. The following dependent measures were extracted from tri-axial trunk accelerations of 20 running steps before and after the treadmill fatigue protocol: the tri-axial ratio of acceleration root mean square (RMS) to the resultant vector RMS, step and stride regularity (autocorrelation procedure), and sample entropy. Running-induced fatigue increased mediolateral and anteroposterior ratios of acceleration RMS (p < .05), decreased the anteroposterior step regularity (p < .05), and increased the anteroposterior sample entropy (p < .05) of trunk accelerometry patterns. Our findings indicate that treadmill running-induced fatigue might reveal itself in a greater contribution of variability in horizontal plane trunk accelerations, with anteroposterior trunk accelerations that are less regular from step-to-step and are less predictable. It appears that trunk accelerometry parameters can be used to detect deviations in dynamic CoM motion induced by treadmill running fatigue, yet it is unknown how robust or generalizable these parameters are to outdoor running environments. PMID:26517261

  8. Rare electrocution due to powerline contact in a hot-air balloon: comparison with fatalities from blunt trauma.

    PubMed

    McConnell, T S; Zumwalt, R E; Wahe, J; Haikal, N A; McFeeley, P J

    1992-09-01

    Powerline contact by hot-air balloons is one of the most frequent concurrences in balloon accidents resulting in injury or death. Injuries and deaths are usually a result of blunt trauma from falls. In this report, we describe the aircraft, the circumstances of the accidents and the autopsy data in two powerline contact accidents involving three deaths, one from electrocution and two, from blunt trauma sustained in falls. Appropriate pilot behavior is briefly discussed. PMID:1402763

  9. Chiral Signatures of Anthropogenic Semi-Volatile Organic Compounds in Asian, trans- Pacific, and Pacific Northwestern Air Masses

    NASA Astrophysics Data System (ADS)

    Genualdi, S.; Primbs, T.; Bidleman, T.; Jantunen, L.; Simonich, S.

    2006-12-01

    The goal of this research is to use the chiral signatures of Semi-Volatile Organic Compounds (SOCs) to distinguish between new and old sources in Asian, trans-Pacific, and regional air masses. During 2004, a six week air sampling campaign was conducted at a remote site in Okinawa, Japan to determine the chemical composition of Eurasian air masses. During 2003 and 2004, high volume air samples were collected at three different locations in the Pacific Northwest of the United States. These sampling locations were; Mary's Peak Observatory (MPO) located at 1250m in the Oregon Coast Range, Mt. Bachelor located at 2800m in Oregon's Cascade Range, and Cheeka Peak Observatory (CPO) located at 500m in the state of Washington. The air samples consisted of both polyurethane foam and XAD-2 resin to collect the gas phase SOCs, and glass fiber filters to collect the particulate phase SOCs. The samples were extracted using accelerated solvent extraction and enantiomer fractions were determined using GCMS-ECNI with the use of a BGB Analytik chiral column. The chiral SOCs, á-Hexachlorocyclohexane, cis and trans chlordane, heptachlor epoxide, and o'p' DDT, were measured, the enantiomer ratios were determined, and potential new and historical sources of these compounds were identified.

  10. Crustal deformation at very long baseline interferometry sites due to seasonal air-mass and ground water variations

    NASA Technical Reports Server (NTRS)

    Stolz, A.; Larden, D. R.

    1980-01-01

    The seasonal deformation normal to the Earth's surface was calculated at stations involved or interested in very long baseline interferometry (VLBI) geodesy and at hypothetical sites in Australia and Brazil using global atmospheric pressure data, values for groundwater storage, and load Love numbers deduced from current Earth models. It was found that the annual range of deformation approached the centimeter level measuring potential of the VLBI technqiue at Greenbank, Haystack, and the Brazil site.

  11. Investigation of levels in ambient air near sources of Polychlorinated Biphenyls (PCBs) in Kanpur, India, and risk assessment due to inhalation.

    PubMed

    Goel, Anubha; Upadhyay, Kritika; Chakraborty, Mrinmoy

    2016-05-01

    Polychlorinated biphenyls (PCBs) are a class of organic compounds listed as persistent organic pollutant and have been banned for use under Stockholm Convention (1972). They were used primarily in transformers and capacitors, paint, flame retardants, plasticizers, and lubricants. PCBs can be emitted through the primary and secondary sources into the atmosphere, undergo long-range atmospheric transport, and hence have been detected worldwide. Reported levels in ambient air are generally higher in urban areas. Active sampling of ambient air was conducted in Kanpur, a densely populated and industrialized city in the Indo-Gangetic Plain, for detection of 32 priority PCBs, with the aim to determine the concentration in gas/particle phase and assess exposure risk. More than 50 % of PCBs were detected in air. Occurrence in particles was dominated by heavier congeners, and levels in gas phase were below detection. Levels determined in this study are lower than the levels in Coastal areas of India but are at par with other Asian countries where majority of sites chosen for sampling were urban industrial areas. Human health risk estimates through air inhalation pathway were made in terms of lifetime average daily dose (LADD) and incremental lifetime cancer risks (ILCR). The study found lower concentrations of PCBs than guideline values and low health risk estimates through inhalation within acceptable levels, indicating a minimum risk to the adults due to exposure to PCBs present in ambient air in Kanpur. PMID:27061805

  12. Modeling study of air pollution due to the manufacture of export goods in China's Pearl River Delta

    SciTech Connect

    David G. Streets; Carolyne Yu; Michael H. Bergin; Xuemei Wang; Gregory R. Carmichael

    2006-04-01

    The Pearl River Delta is a major manufacturing region on the south coast of China that produces more than $100 billion of goods annually for export to North America, Europe, and other parts of Asia. Considerable air pollution is caused by the manufacturing industries themselves and by the power plants, trucks, and ships that support them. It is estimated that 10-40% of emissions of primary SO{sub 2}, NOx, RSP, and VOC in the region are caused by export-related activities. Using the STEM-2K1 atmospheric transport model, it is estimated that these emissions contribute 5-30% of the ambient concentrations of SO{sub 2}, NOx, NOz, and VOC in the region. (NO{sub Z}=PAN, HONO, HNO{sub 3}, N{sub 2}O{sub 5} and organic nitrates). One reason that the exported goods are cheap and therefore attractive to consumers in developed countries is that emission controls are lacking or of low performance. It is estimated that state-of-the-art controls could be installed at an annualized cost of $0.3-3 billion, representing 0.3-3% of the value of the goods produced. Mitigation measures could be adopted without seriously affecting the prices of exported goods and would achieve considerable human health and other benefits in the form of reduced air pollutant concentrations in densely populated urban areas. 22 refs., 5 figs., 5 tabs.

  13. Changes in air quality and tropospheric composition due to depletion of stratospheric ozone and interactions with climate.

    PubMed

    Tang, X; Wilson, S R; Solomon, K R; Shao, M; Madronich, S

    2011-02-01

    Air pollution will be directly influenced by future changes in emissions of pollutants, climate, and stratospheric ozone, and will have significant consequences for human health and the environment. UV radiation is one of the controlling factors for the formation of photochemical smog, which includes tropospheric ozone (O(3)) and aerosols; it also initiates the production of hydroxyl radicals (˙OH), which control the amount of many climate- and ozone-relevant gases (e.g., methane and HCFCs) in the atmosphere. Numerical models predict that future changes in UV radiation and climate will modify the trends and geographic distribution of ˙OH, thus affecting the formation of photochemical smog in many urban and regional areas. Concentrations of ˙OH are predicted to decrease globally by an average of 20% by 2100, with local concentrations varying by as much as a factor of two above and below current values. However, significant differences between modelled and measured values in a limited number of case studies show that chemistry of hydroxyl radicals in the atmosphere is not fully understood. Photochemically produced tropospheric ozone is projected to increase. If emissions of anthropogenic air pollutants from combustion of fossil fuels, burning of biomass, and agricultural activities continue to increase, concentrations of tropospheric O(3) will tend to increase over the next 20-40 years in certain regions of low and middle latitudes because of interactions of emissions, chemical processes, and climate change. Climate-driven increases in temperature and humidity will also increase production of tropospheric O(3) in polluted regions, but reduce it in more pristine regions. Higher temperatures tend to increase emissions of nitrogen oxides (NO(x)) from some soils and release of biogenic volatile organic compounds (VOCs) from vegetation, leading to greater background concentrations of ozone in the troposphere. The net effects of future changes in UV radiation

  14. Determination of respirable mass concentration using a high volume air sampler and a sedimentation method for fractionation

    SciTech Connect

    Johnson, J.

    1995-12-31

    A preliminary study of a new method for determining respirable mass concentration is described. This method uses a high volume air sampler and subsequent fractionation of the collected mass using a particle sedimentation technique. Side-by-side comparisons of this method with cyclones were made in the field and in the laboratory. There was good agreement among the samplers in the laboratory, but poor agreement in the field. The effect of wind on the samplers` capture efficiencies is the primary hypothesized source of error among the field results. The field test took place at the construction site of a hazardous waste landfill located on the Hanford Reservation.

  15. Study of the Tropospheric Aerosol Structure Under Changing of the Air Mass Type from Lidar Observations in Tomsk

    NASA Astrophysics Data System (ADS)

    Samoilova, S. V.; Balin, Yu. S.; Kokhanenko, G. P.; Penner, I. É.

    2016-04-01

    The aerosol optical characteristics in the main tropospheric layers are investigated based on joint interpretation of data of multi-frequency lidar sensing (110 sessions) and results of modeling of back air mass trajectories. Methodical problems for separating layers with different scattering properties and estimating their vertical boundaries are considered. Three optical criteria are simultaneously used to distinguish aerosol layers from cloud formations, including the gradient of the backscattering coefficient, optical depth, and the depolarization ratio. High values of the lidar ratio (66 sr) and of the Angstrom exponent (1.62) in the shortwavelength spectral range are observed in the boundary layer for Arctic transport. At the same time, low values of these optical parameters are characteristic for Asian transport: the lidar ratio is 54 sr and the Angstrom exponent is 1.1, which is explained by different relative contributions of the coarse and fine aerosol fractions to the air mass.

  16. Calculations of relative optical air masses for various aerosol types and minor gases in Arctic and Antarctic atmospheres

    NASA Astrophysics Data System (ADS)

    Tomasi, Claudio; Petkov, Boyan H.

    2014-02-01

    The dependence functions of relative optical air mass on apparent solar zenith angle θ have been calculated over the θ < 87° range for the vertical profiles of wet-air molecular number density in the Arctic and Antarctic atmospheres, extinction coefficients of different aerosol types, and molecular number density of water vapor, ozone, nitrogen dioxide, and oxygen dimer. The calculations were made using as weight functions the seasonal average vertical profiles of (i) pressure and temperature derived from multiyear sets of radiosounding measurements performed at Ny-Ålesund, Alert, Mario Zucchelli, and Neumayer stations; (ii) volume extinction coefficients of background summer aerosol, Arctic haze, and Kasatochi and Pinatubo volcanic aerosol measured with lidars or balloon-borne samplings; and (iii) molecular number concentrations of the above minor gases, derived from radiosonde, ozonesonde, and satellite-based observations. The air mass values were determined using a formula based on a realistic atmospheric air-refraction model. They were systematically checked by comparing their mutual differences with the uncertainties arising from the seasonal and daily variations in pressure and temperature conditions within the various ranges, where aerosol and gases attenuate the solar radiation most efficiently. The results provide evidence that secant-approximated and midlatitude air mass values are inappropriate for analyzing the Sun photometer measurements performed at polar sites. They indicate that the present evaluations can be reliably used to estimate the aerosol optical depth from the Arctic and Antarctic measurements of total optical depth, after appropriate corrections for the Rayleigh scattering and gaseous absorption optical depths.

  17. Screening for sarin in air and water by solid-phase microextraction-gas chromatography/mass spectrometry.

    SciTech Connect

    Schneider, J. F.; Boparai, A. S.; Reed, L. L.

    2001-10-01

    A method of screening air and water samples for the chemical-warfare agent Sarin is developed using solid-phase microextraction (SPME)-gas chromatography (GC)-mass spectrometry (MS). The SPME field kit sampler is ideal for collecting air and water samples in the field and transporting samples safely to the laboratory. The sampler also allows the sample to be introduced into the GC-MS system without further sample preparation. Results of the tests with Sarin using the SPME technique indicate that a sample collection time of 5 min is sufficient to detect 100 ng/L of Sarin in air. For water samples, Sarin is detected at a concentration of 12 {mu}g/mL or higher. This method is ideal for screening samples for quick response situations.

  18. On the relationship between Arctic ice clouds and polluted air masses over the north slope of Alaska in April 2008

    NASA Astrophysics Data System (ADS)

    Jouan, C.; Pelon, J.; Girard, E.; Ancellet, G.; Blanchet, J. P.; Delanoë, J.

    2013-02-01

    Recently, two Types of Ice Clouds (TICs) properties have been characterized using ISDAC airborne measurements (Alaska, April 2008). TIC-2B were characterized by fewer (<10 L-1) and larger (>110 μm) ice crystals, a larger ice supersaturation (>15%) and a fewer ice nuclei (IN) concentration (<2 order of magnitude) when compared to TIC-1/2A. It has been hypothesized that emissions of SO2 may reduce the ice nucleating properties of IN through acidification, resulting to a smaller concentration of larger ice crystals and leading to precipitation (e.g. cloud regime TIC-2B) because of the reduced competition for the same available moisture. Here, the origin of air masses forming the ISDAC TIC-1/2A (1 April 2008) and TIC-2B (15 April 2008) is investigated using trajectory tools and satellite data. Results show that the synoptic conditions favor air masses transport from the three potentials SO2 emission areas to Alaska: eastern China and Siberia where anthropogenic and biomass burning emission respectively are produced and the volcanic region from the Kamchatka/Aleutians. Weather conditions allow the accumulation of pollutants from eastern China/Siberia over Alaska, most probably with the contribution of acid volcanic aerosol during the TIC-2B period. OMI observations reveal that SO2 concentrations in air masses forming the TIC-2B were larger than in air masses forming the TIC-1/2A. Airborne measurements show high acidity near the TIC-2B flight where humidity was low. These results strongly support the hypothesis that acidic coating on IN are at the origin of the formation of TIC-2B.

  19. On the relationship between Arctic ice clouds and polluted air masses over the North Slope of Alaska in April 2008

    NASA Astrophysics Data System (ADS)

    Jouan, C.; Pelon, J.; Girard, E.; Ancellet, G.; Blanchet, J. P.; Delanoë, J.

    2014-02-01

    Recently, two types of ice clouds (TICs) properties have been characterized using the Indirect and Semi-Direct Aerosol Campaign (ISDAC) airborne measurements (Alaska, April 2008). TIC-2B were characterized by fewer (< 10 L-1) and larger (> 110 μm) ice crystals, and a larger ice supersaturation (> 15%) compared to TIC-1/2A. It has been hypothesized that emissions of SO2 may reduce the ice nucleating properties of ice nuclei (IN) through acidification, resulting in a smaller concentration of larger ice crystals and leading to precipitation (e.g., cloud regime TIC-2B). Here, the origin of air masses forming the ISDAC TIC-1/2A (1 April 2008) and TIC-2B (15 April 2008) is investigated using trajectory tools and satellite data. Results show that the synoptic conditions favor air masses transport from three potential SO2 emission sources into Alaska: eastern China and Siberia where anthropogenic and biomass burning emissions, respectively, are produced, and the volcanic region of the Kamchatka/Aleutians. Weather conditions allow the accumulation of pollutants from eastern China and Siberia over Alaska, most probably with the contribution of acidic volcanic aerosol during the TIC-2B period. Observation Monitoring Instrument (OMI) satellite observations reveal that SO2 concentrations in air masses forming the TIC-2B were larger than in air masses forming the TIC-1/2A. Airborne measurements show high acidity near the TIC-2B flight where humidity was low. These results support the hypothesis that acidic coating on IN could be at the origin of the formation of TIC-2B.

  20. On the Aerosol Particle Size Distribution Spectrum in Alaskan Air Mass Systems: Arctic Haze and Non-Haze Episodes.

    NASA Astrophysics Data System (ADS)

    Shaw, Glenn E.

    1983-05-01

    Aerosols in central Alaskan winter air mass system were classified according to size by diffusive separation and light-scattering spectrometry. Particles entering central Alaska from the Pacific Marine environment had number concentrations ranging from 300 to 2000 cm3 (geometric mean 685 cm3) and unimodal size spectra, with maximum in number concentration near 1 × 106 cm radius.Air masses entering Alaska from the Eurasian Arctic possessed a factor of two smaller aerosol number concentrations than Pacific Marine systems (e.g., 150-700 cm3; geometric mean 386 cm3) but contained a factor of two greater particle volume loading within the fine particle radius range 5 × 107 < r < 1 × 105 cm. The particles in Eurasian Arctic air masses were bimodally distributed, with maxima in the particle size spectra near r = 3 × 107 and 5 × 106 cm. Sulfur was the predominant element in all cases studied.A particle depleted region was present in the size spectra obtained for Eurasian Arctic air masses. The deficiency of particles in the 106 cm radius range is interpreted as being the result of thermal coagulation taking place between sulfur-rich nuclei (produced at a rate of 1020 to 1018 g cm3 s1 and in sizes r < 106 cm) and `large' (r 105 cm) imported primary particles. The primary particles are in the removal-resistant Greenfield Gap (r 105 cm) and seem to originate in the central Eurasian region.

  1. Influence of power ultrasound application on mass transport and microstructure of orange peel during hot air drying

    NASA Astrophysics Data System (ADS)

    Ortuño, Carmen; Pérez-Munuera, Isabel; Puig, Ana; Riera, Enrique; Garcia-Perez, J. V.

    2010-01-01

    Power ultrasound application on convective drying of foodstuffs may be considered an emergent technology. This work deals with the influence of power ultrasound on drying of natural materials addressing the kinetic as well as the product's microstructure. Convective drying kinetics of orange peel slabs (thickness 5.95±0.41 mm) were carried out at 40 ∘C and 1 m/s with (US) and without (AIR) power ultrasound application. A diffusion model considering external resistance to mass transfer was considered to describe drying kinetics. Fresh, US and AIR dried samples were analyzed using Cryo-SEM. Results showed that drying kinetics of orange peel were significantly improved by the application of power ultrasound. From modeling, it was observed a significant (p¡0.05) increase in both mass transfer coefficient and effective moisture diffusivity. The effects on mass transfer properties were confirmed from microestructural observations. In the cuticle surface, the pores were obstructed by wax components scattering, which evidence the ultrasonic effects on the interfaces. The cells of the flavedo were compressed and large intercellular air spaces were generated in the albedo facilitating water transfer through it.

  2. Features of air masses associated with the deposition of Pseudomonas syringae and Botrytis cinerea by rain and snowfall

    PubMed Central

    Monteil, Caroline L; Bardin, Marc; Morris, Cindy E

    2014-01-01

    Clarifying the role of precipitation in microbial dissemination is essential for elucidating the processes involved in disease emergence and spread. The ecology of Pseudomonas syringae and its presence throughout the water cycle makes it an excellent model to address this issue. In this study, 90 samples of freshly fallen rain and snow collected from 2005–2011 in France were analyzed for microbiological composition. The conditions favorable for dissemination of P. syringae by this precipitation were investigated by (i) estimating the physical properties and backward trajectories of the air masses associated with each precipitation event and by (ii) characterizing precipitation chemistry, and genetic and phenotypic structures of populations. A parallel study with the fungus Botrytis cinerea was also performed for comparison. Results showed that (i) the relationship of P. syringae to precipitation as a dissemination vector is not the same for snowfall and rainfall, whereas it is the same for B. cinerea and (ii) the occurrence of P. syringae in precipitation can be linked to electrical conductivity and pH of water, the trajectory of the air mass associated with the precipitation and certain physical conditions of the air mass (i.e. temperature, solar radiation exposure, distance traveled), whereas these predictions are different for B. cinerea. These results are pertinent to understanding microbial survival, emission sources and atmospheric processes and how they influence microbial dissemination. PMID:24722630

  3. Acute Effects of Outdoor Air Pollution on Emergency Department Visits Due to Five Clinical Subtypes of Coronary Heart Diseases in Shanghai, China

    PubMed Central

    Xie, Juan; He, Mingzhen; Zhu, Weiying

    2014-01-01

    Background Air pollution can be a contributing cause to the development and exacerbation of coronary heart disease (CHD), but there is little knowledge about the acute effects of air pollution on different clinical subtypes of CHD. Methods We conducted a time-series study to investigate the association of air pollution (particulate matter with an aerodynamic diameter < 10 µm [PM10], sulfur dioxide [SO2], and nitrogen dioxide [NO2]) on emergency department (ED) visits due to five different subtypes of CHD in Shanghai, China, from 2010 to 2012. We applied an over-dispersed Poisson generalized addictive model to analyze the associations after controlling for the seasonality, day of the week, and weather conditions. Results We identified a total of 47 523 ED visits for CHD. A 10-µg/m3 increase in the present-day concentrations of PM10, SO2, and NO2 was associated with respective increases of 1.10% (95% confidence interval [CI] 0.33%–1.87%), 0.90% (95% CI −0.14%–1.93%), and 1.44% (95% CI 0.63%–2.26%) for total ED visits for CHD. These associations varied greatly by clinical type, with strong effects on sudden cardiac death, moderate effects on acute myocardial infarction and angina, weak effects on ischemic cardiomyopathy, and no effect on occult CHD. The associations were stronger among people aged 65 years or more than in younger individuals and in the cool season versus the warm one. Conclusions Outdoor air pollution may have different effects of air pollution on 5 subtypes of CHD. Our results might be useful for the primary prevention of various subtypes of CHD exacerbated by air pollution. PMID:24998952

  4. Constraining Aerosol Optical Models Using Ground-Based, Collocated Particle Size and Mass Measurements in Variable Air Mass Regimes During the 7-SEAS/Dongsha Experiment

    NASA Technical Reports Server (NTRS)

    Bell, Shaun W.; Hansell, Richard A.; Chow, Judith C.; Tsay, Si-Chee; Wang, Sheng-Hsiang; Ji, Qiang; Li, Can; Watson, John G.; Khlystov, Andrey

    2012-01-01

    During the spring of 2010, NASA Goddard's COMMIT ground-based mobile laboratory was stationed on Dongsha Island off the southwest coast of Taiwan, in preparation for the upcoming 2012 7-SEAS field campaign. The measurement period offered a unique opportunity for conducting detailed investigations of the optical properties of aerosols associated with different air mass regimes including background maritime and those contaminated by anthropogenic air pollution and mineral dust. What appears to be the first time for this region, a shortwave optical closure experiment for both scattering and absorption was attempted over a 12-day period during which aerosols exhibited the most change. Constraints to the optical model included combined SMPS and APS number concentration data for a continuum of fine and coarse-mode particle sizes up to PM2.5. We also take advantage of an IMPROVE chemical sampler to help constrain aerosol composition and mass partitioning of key elemental species including sea-salt, particulate organic matter, soil, non sea-salt sulphate, nitrate, and elemental carbon. Our results demonstrate that the observed aerosol scattering and absorption for these diverse air masses are reasonably captured by the model, where peak aerosol events and transitions between key aerosols types are evident. Signatures of heavy polluted aerosol composed mostly of ammonium and non sea-salt sulphate mixed with some dust with transitions to background sea-salt conditions are apparent in the absorption data, which is particularly reassuring owing to the large variability in the imaginary component of the refractive indices. Extinctive features at significantly smaller time scales than the one-day sample period of IMPROVE are more difficult to reproduce, as this requires further knowledge concerning the source apportionment of major chemical components in the model. Consistency between the measured and modeled optical parameters serves as an important link for advancing remote

  5. Chemical compositions and radiative properties of dust and anthropogenic air masses study in Taipei Basin, Taiwan, during spring of 2004

    NASA Astrophysics Data System (ADS)

    Chang, Shih-Yu; Fang, Guor-Cheng; Chou, Charles C.-K.; Chen, Wei-Nai

    Asia is one of the major sources of not only mineral dust but also anthropogenic aerosols. Continental air masses associated with the East Asian winter monsoon always contain high contents of mineral dust and anthropogenic species and transported southeastward to Taiwan, which have significant influences on global atmospheric radiation transfer directly by scattering and absorbing solar radiation in each spring. However, few measurements for the long-range transported aerosol and its optical properties were announced in this area, between the Western Pacific and the southeastern coast of Mainland China. The overall objective of this work is to quantify the optical characteristics of different aerosol types in the Eastern Asian. In order to achieve this objective, meteorological parameters, concentrations of PM 10 and its soluble species, and optical property of atmospheric scattering coefficients were measured continuously with 1 h time-resolved from 11 February to 7 April 2004 in Taipei Basin (25°00'N, 121°32'E). In this work, the dramatic changes of meteorological parameters such as temperature and winds were used to determine the influenced period of each air mass. Continental, strong continental, marine, and stagnant air masses defined by the back-trajectory analysis and local meteorology were further characterized as long-range transport pollution, dust, clean marine, and local pollution aerosols, respectively, according to the diagnostic ratios. The aerosol mass scattering efficiency of continental pollution, dust, clean marine, and local pollution aerosols were ranged from 1.3 to 1.6, 0.7 to 1.0, 1.4 and 1.4 to 2.3 m 2 g -1, respectively. Overall, there are two distinct populations of aerosol mass scattering efficiencies, one for an aerosol chemical composition dominated by dust (<1.0 m 2 g -1) and the other for an aerosol chemical composition dominated by anthropogenic pollutants (1.3-2.3 m 2 g -1), which were similar to the previous measurements with

  6. Experimental Validation of a Forward Looking Interferometer for Detection of Clear Air Turbulence due to Mountain Waves

    NASA Technical Reports Server (NTRS)

    Schaffner, Philip R.; Daniels, Taumi S.; West, Leanne L.; Gimmestad, Gary G.; Lane, Sarah E.; Burdette, Edward M.; Smith, William L.; Kireev, Stanislav; Cornman, Larry; Sharman, Robert D.

    2012-01-01

    The Forward-Looking Interferometer (FLI) is an airborne sensor concept for detection and estimation of potential atmospheric hazards to aircraft. The FLI concept is based on high-resolution Infrared Fourier Transform Spectrometry technologies that have been developed for satellite remote sensing. The FLI is being evaluated for its potential to address multiple hazards, during all phases of flight, including clear air turbulence, volcanic ash, wake vortices, low slant range visibility, dry wind shear, and icing. In addition, the FLI is being evaluated for its potential to detect hazardous runway conditions during landing, such as wet or icy asphalt or concrete. The validation of model-based instrument and hazard simulation results is accomplished by comparing predicted performance against empirical data. In the mountain lee wave data collected in the previous FLI project, the data showed a damped, periodic mountain wave structure. The wave data itself will be of use in forecast and nowcast turbulence products such as the Graphical Turbulence Guidance and Graphical Turbulence Guidance Nowcast products. Determining how turbulence hazard estimates can be derived from FLI measurements will require further investigation.

  7. Investigations of Pulmonary Epithelial Cell Damage due to Air-Liquid Interfacial Stresses in a Microgravity Environment

    NASA Technical Reports Server (NTRS)

    Gaver, Donald P., III; Bilek, A. M.; Kay, S.; Dee, K. C.

    2004-01-01

    Pulmonary airway closure is a potentially dangerous event that can occur in microgravity environments and may result in limited gas exchange for flight crew during long-term space flight. Repetitive airway collapse and reopening subjects the pulmonary epithelium to large, dynamic, and potentially injurious mechanical stresses. During ventilation at low lung volumes and pressures, airway instability leads to repetitive collapse and reopening. During reopening, air must progress through a collapsed airway, generating stresses on the airway walls, potentially damaging airway tissues. The normal lung can tolerate repetitive collapse and reopening. However, combined with insufficient or dysfunctional pulmonary surfactant, repetitive airway collapse and reopening produces severe lung injury. Particularly at risk is the pulmonary epithelium. As an important regulator of lung function and physiology, the degree of pulmonary epithelial damage influences the course and outcome of lung injury. In this paper we present experimental and computational studies to explore the hypothesis that the mechanical stresses associated with airway reopening inflict injury to the pulmonary epithelium.

  8. International system of units traceable results of Hg mass concentration at saturation in air from a newly developed measurement procedure.

    PubMed

    Quétel, Christophe R; Zampella, Mariavittoria; Brown, Richard J C; Ent, Hugo; Horvat, Milena; Paredes, Eduardo; Tunc, Murat

    2014-08-01

    Data most commonly used at present to calibrate measurements of mercury vapor concentrations in air come from a relationship known as the "Dumarey equation". It uses a fitting relationship to experimental results obtained nearly 30 years ago. The way these results relate to the international system of units (SI) is not known. This has caused difficulties for the specification and enforcement of limit values for mercury concentrations in air and in emissions to air as part of national or international legislation. Furthermore, there is a significant discrepancy (around 7% at room temperature) between the Dumarey data and data calculated from results of mercury vapor pressure measurements in the presence of only liquid mercury. As an attempt to solve some of these problems, a new measurement procedure is described for SI traceable results of gaseous Hg concentrations at saturation in milliliter samples of air. The aim was to propose a scheme as immune as possible to analytical biases. It was based on isotope dilution (ID) in the liquid phase with the (202)Hg enriched certified reference material ERM-AE640 and measurements of the mercury isotope ratios in ID blends, subsequent to a cold vapor generation step, by inductively coupled plasma mass spectrometry. The process developed involved a combination of interconnected valves and syringes operated by computer controlled pumps and ensured continuity under closed circuit conditions from the air sampling stage onward. Quantitative trapping of the gaseous mercury in the liquid phase was achieved with 11.5 μM KMnO4 in 2% HNO3. Mass concentrations at saturation found from five measurements under room temperature conditions were significantly higher (5.8% on average) than data calculated from the Dumarey equation, but in agreement (-1.2% lower on average) with data based on mercury vapor pressure measurement results. Relative expanded combined uncertainties were estimated following a model based approach. They ranged from 2

  9. Stability of reference masses: VII. Cleaning methods in air and vacuum applied to a platinum mass standard similar to the international and national kilogram prototypes

    NASA Astrophysics Data System (ADS)

    Cumpson, Peter J.; Sano, Naoko; Barlow, Anders J.; Portoles, Jose F.

    2013-10-01

    Mercury contamination and the build-up of carbonaceous contamination are two contributing factors to the instability observed in kilogram prototype masses. The kilogram prototypes that lie at the core of the dissemination of the SI base unit were manufactured in the late 19th century, and have polished surfaces. In papers IV and V of this series we developed a method for cleaning noble metal mass standards in air to remove carbonaceous contamination. At the core of this ‘UVOPS’ protocol is the application of UV light and ozone gas generated in situ in air. The precise nature of the carbonaceous contamination that builds up on such surfaces is difficult to mimic demonstrably or quickly on new test surfaces, yet data from such tests are needed to provide the final confidence to allow UVOPS to be applied to a real 19th century kilogram prototype. Therefore, in the present work we have applied the UVOPS method to clean a platinum avoirdupois pound mass standard, ‘RS2’, manufactured in the mid-19th century. This is thought to have been polished in a similar manner to the kilogram prototypes. To our knowledge this platinum surface has not previously been cleaned by any method. We used x-ray photoelectron spectroscopy to identify organic contamination, and weighing to quantify the mass lost at each application of the UVOPS procedure. The UVOPS procedure is shown to be very effective. It is likely that the redefinition of the kilogram will require mass comparisons in vacuum in the years to come. Therefore, in addition to UVOPS a cleaning method for use in vacuum will also be needed. We introduce and evaluate gas cluster ion-beam (GCIB) treatment as a potential method for cleaning reference masses in vacuum. Again, application of this GCIB cleaning to a real artefact, RS2, allows us to make a realistic evaluation of its performance. While it has some attractive features, we cannot recommend it for cleaning mass standards in its present form.

  10. Mass

    SciTech Connect

    Chris Quigg

    2007-12-05

    In the classical physics we inherited from Isaac Newton, mass does not arise, it simply is. The mass of a classical object is the sum of the masses of its parts. Albert Einstein showed that the mass of a body is a measure of its energy content, inviting us to consider the origins of mass. The protons we accelerate at Fermilab are prime examples of Einsteinian matter: nearly all of their mass arises from stored energy. Missing mass led to the discovery of the noble gases, and a new form of missing mass leads us to the notion of dark matter. Starting with a brief guided tour of the meanings of mass, the colloquium will explore the multiple origins of mass. We will see how far we have come toward understanding mass, and survey the issues that guide our research today.

  11. Surface analysis using a new plasma assisted desorption/ionisation source for mass spectrometry in ambient air

    NASA Astrophysics Data System (ADS)

    Bowfield, A.; Barrett, D. A.; Alexander, M. R.; Ortori, C. A.; Rutten, F. M.; Salter, T. L.; Gilmore, I. S.; Bradley, J. W.

    2012-06-01

    The authors report on a modified micro-plasma assisted desorption/ionisation (PADI) device which creates plasma through the breakdown of ambient air rather than utilising an independent noble gas flow. This new micro-PADI device is used as an ion source for ambient mass spectrometry to analyse species released from the surfaces of polytetrafluoroethylene, and generic ibuprofen and paracetamol tablets through remote activation of the surface by the plasma. The mass spectra from these surfaces compare favourably to those produced by a PADI device constructed using an earlier design and confirm that the new ion source is an effective device which can be used to achieve ambient mass spectrometry with improved spatial resolution.

  12. A Method for Incorporating Changing Structural Characteristics Due to Propellant Mass Usage in a Launch Vehicle Ascent Simulation

    NASA Technical Reports Server (NTRS)

    McGhee, D. S.

    2004-01-01

    Launch vehicles consume large quantities of propellant quickly, causing the mass properties and structural dynamics of the vehicle to change dramatically. Currently, structural load assessments account for this change with a large collection of structural models representing various propellant fill levels. This creates a large database of models complicating the delivery of reduced models and requiring extensive work for model changes. Presented here is a method to account for these mass changes in a more efficient manner. The method allows for the subtraction of propellant mass as the propellant is used in the simulation. This subtraction is done in the modal domain of the vehicle generalized model. Additional computation required is primarily for constructing the used propellant mass matrix from an initial propellant model and further matrix multiplications and subtractions. An additional eigenvalue solution is required to uncouple the new equations of motion; however, this is a much simplier calculation starting from a system that is already substantially uncoupled. The method was successfully tested in a simulation of Saturn V loads. Results from the method are compared to results from separate structural models for several propellant levels, showing excellent agreement. Further development to encompass more complicated propellant models, including slosh dynamics, is possible.

  13. STROBE-Long-Term Exposure to Ambient Fine Particulate Air Pollution and Hospitalization Due to Peptic Ulcers

    PubMed Central

    Wong, Chit-Ming; Tsang, Hilda; Lai, Hak-Kan; Thach, Thuan-Quoc; Thomas, G. Neil; Chan, King-Pan; Lee, Siu-Yin; Ayres, Jon G.; Lam, Tai-Hing; Leung, Wai K.

    2016-01-01

    Abstract Little is known about the effect of air pollution on the gastrointestinal (GI) system. We investigated the association between long-term exposures to outdoor fine particles (PM2.5) and hospitalization for peptic ulcer diseases (PUDs) in a large cohort of Hong Kong Chinese elderly. A total of 66,820 subjects aged ≥65 years who were enrolled in all 18 Government Elderly Health Service centers of Hong Kong participated in the study voluntarily between 1998 and 2001. They were prospectively followed up for more than 10 years. Annual mean exposures to PM2.5 at residence of individuals were estimated by satellite data through linkage with address details including floor level. All hospital admission records of the subjects up to December 31, 2010 were retrieved from the central database of Hospital Authority. We used Cox regression to estimate the hazard ratio (HR) for PUD hospitalization associated with PM2.5 exposure after adjustment for individual and ecological covariates. A total of 60,273 subjects had completed baseline information including medical, socio-demographic, lifestyle, and anthropometric data at recruitment. During the follow-up period, 1991 (3.3%) subjects had been hospitalized for PUD. The adjusted HR for PUD hospitalization per 10 μg/m3 of PM2.5 was 1.18 (95% confidence interval: 1.02–1.36, P = 0.02). Further analysis showed that the associations with PM2.5 were significant for gastric ulcers (HR 1.29; 1.09–1.53, P = 0.003) but not for duodenal ulcers (HR 0.98; 0.78 to 1.22, P = 0.81). Long-term exposures to PM2.5 were associated with PUD hospitalization in elder population. The mechanism underlying the PM2.5 in the development of gastric ulcers warrants further research. PMID:27149464

  14. STROBE-Long-Term Exposure to Ambient Fine Particulate Air Pollution and Hospitalization Due to Peptic Ulcers.

    PubMed

    Wong, Chit-Ming; Tsang, Hilda; Lai, Hak-Kan; Thach, Thuan-Quoc; Thomas, G Neil; Chan, King-Pan; Lee, Siu-Yin; Ayres, Jon G; Lam, Tai-Hing; Leung, Wai K

    2016-05-01

    Little is known about the effect of air pollution on the gastrointestinal (GI) system. We investigated the association between long-term exposures to outdoor fine particles (PM2.5) and hospitalization for peptic ulcer diseases (PUDs) in a large cohort of Hong Kong Chinese elderly.A total of 66,820 subjects aged ≥65 years who were enrolled in all 18 Government Elderly Health Service centers of Hong Kong participated in the study voluntarily between 1998 and 2001. They were prospectively followed up for more than 10 years. Annual mean exposures to PM2.5 at residence of individuals were estimated by satellite data through linkage with address details including floor level. All hospital admission records of the subjects up to December 31, 2010 were retrieved from the central database of Hospital Authority. We used Cox regression to estimate the hazard ratio (HR) for PUD hospitalization associated with PM2.5 exposure after adjustment for individual and ecological covariates.A total of 60,273 subjects had completed baseline information including medical, socio-demographic, lifestyle, and anthropometric data at recruitment. During the follow-up period, 1991 (3.3%) subjects had been hospitalized for PUD. The adjusted HR for PUD hospitalization per 10 μg/m of PM2.5 was 1.18 (95% confidence interval: 1.02-1.36, P = 0.02). Further analysis showed that the associations with PM2.5 were significant for gastric ulcers (HR 1.29; 1.09-1.53, P = 0.003) but not for duodenal ulcers (HR 0.98; 0.78 to 1.22, P = 0.81).Long-term exposures to PM2.5 were associated with PUD hospitalization in elder population. The mechanism underlying the PM2.5 in the development of gastric ulcers warrants further research. PMID:27149464

  15. Chemical and Trajectory Analysis of an Air Mass Plume from Asia

    NASA Astrophysics Data System (ADS)

    Guo, J. J.; Marrero, J. E.; Blake, D. R.

    2014-12-01

    Tracking the source of pollution events is important in understanding the transport of pollution plumes and impact on areas far from the source. Previous studies have shown that the rising contribution of Asian air pollution to the US has increased the number of days that pollution events exceed National Ambient Air Quality Standards (NAAQS). Whole air samples collected over the Edwards Air Force Base during a June 2014 NASA Student Airborne Research Program (SARP) flight exhibited enhancements in the concentrations of several compounds between 23-32 thousand feet. Chemical tracer analysis of these high altitude samples reveal that the air does not correspond to California emitted air. Chemical signatures in the plume, including high levels of OCS, chloroform, and methyl chloride, and low levels of methyl bromide, indicate that the plume was most heavily influence by coal combustion with contributions from biomass burning events from Asia. Low concentrations of ethene at the high altitude despite enhanced concentrations of ethane and ethyne suggest that this plume was aged. Further analysis of the plume using meteorological wind trajectories reveal that the plume had originated in China approximately 4-5 days prior. This is faster than results from previous studies that had found a Spring transport time of approximately 6 days.

  16. A Comparison of the Red Green Blue (RGB) Air Mass Imagery and Hyperspectral Infrared Retrieved Profiles and NOAA G-IV Dropsondes

    NASA Technical Reports Server (NTRS)

    Berndt, Emily; Folmer, Michael; Dunion, Jason

    2014-01-01

    RGB air mass imagery is derived from multiple channels or paired channel differences. The combination of channels and channel differences means the resulting imagery does not represent a quantity or physical parameter such as brightness temperature in conventional single channel imagery. Without a specific quantity to reference, forecasters are often confused as to what RGB products represent. Hyperspectral infrared retrieved profiles and NOAA G-IV dropsondes provide insight about the vertical structure of the air mass represented on the RGB air mass imagery and are a first step to validating the imagery.

  17. Modeling of the relationship between the environmental air pollution, clinical risk factors, and hospital mortality due to myocardial infarction in Isfahan, Iran

    PubMed Central

    Sadeghi, Mehraban; Ahmadi, Ali; Baradaran, Azar; Masoudipoor, Neda; Frouzandeh, Soleiman

    2015-01-01

    Background: This study aimed to determine the relationship between the environmental factor, clinical risk factors, and individual variables with mortality due to acute myocardial infarction (MI) in Isfahan. Materials and Methods: This cross-sectional study was performed between April 2012 and March 2013. The data on the patients’ mortality due to MI in Isfahan were obtained from the MI National Registry. The international classification system (ICD10: I21-I22) was used to diagnose MI. The air quality indicators and environmental variables were used to measure the air pollution. Multilevel logistic regression in the Stata software was used to determine the factors associated with mortality in patients and odds ratios (ORs) were calculated. Results: Six hundred eleven patients with MI were studied during 1-year. 444 (72.2%) patients were male and the rest were female. 4.7% of the patients died due to MI. The mean age at MI incidence was 62.2 ± 13 years. Of the air pollution parameters, PM10 had the maximum mean concentration (49.113 ppm), followed by NOX, NO, NO2, CO, SO2, and O3. The adjusted OR of mortality was derived 2.07 (95% CI: 1.5-2.85) for right bundle branch block, 1.5 (95% CI: 1.3-1.7) for ST-segment elevation MI, 1.84 (95% CI: 1.13-3) for age, 1.06 (95% CI: 1.01-1.20) for CO, 1.1 (95% CI: 1.03-1.30) for O3, and 1.04 (95% CI: 1.01-1.4) for SO2, all of which were considered as the risk factors of mortality. However, OR of mortality was 0.79 for precipitation (95% CI: 0.74-0.84) and 0.52 for angioplasty (95% CI: 0.4-0.68) were considered as protective factors of mortality. The individual characteristics including age, history of MI in the immediate family, hypertension, and diabetes were significantly associated with mortality from MI. The indices of air pollution including SO2, CO, O3, and environmental factors such as the precipitation and temperature were the determinants of mortality in patients with MI. Conclusion: With regards to the factors

  18. Suppressed Magnetic Circular Dichroism and Valley-Selective Magnetoabsorption due to the Effective Mass Anisotropy in Bismuth

    NASA Astrophysics Data System (ADS)

    de Visser, Pieter J.; Levallois, Julien; Tran, Michaël K.; Poumirol, Jean-Marie; Nedoliuk, Ievgeniia O.; Teyssier, Jérémie; Uher, Ctirad; van der Marel, Dirk; Kuzmenko, Alexey B.

    2016-07-01

    We measure the far-infrared reflectivity and Kerr angle spectra on a high-quality crystal of pure semimetallic bismuth as a function of magnetic field, from which we extract the conductivity for left- and right-handed circular polarizations. The high spectral resolution allows us to separate the intraband Landau level transitions for electrons and holes. The hole transition exhibits 100% magnetic circular dichroism; it appears only for one polarization as expected for a circular cyclotron orbit. However, the dichroism for electron transitions is reduced to only 13 ±1 %, which is quantitatively explained by the large effective mass anisotropy of the electron pockets of the Fermi surface. This observation is a signature of the mismatch between the metric experienced by the photons and the electrons. It allows for a contactless measurement of the effective mass anisotropy and provides a direction towards valley polarized magnetooptical pumping with elliptically polarized light.

  19. Suppressed Magnetic Circular Dichroism and Valley-Selective Magnetoabsorption due to the Effective Mass Anisotropy in Bismuth.

    PubMed

    de Visser, Pieter J; Levallois, Julien; Tran, Michaël K; Poumirol, Jean-Marie; Nedoliuk, Ievgeniia O; Teyssier, Jérémie; Uher, Ctirad; van der Marel, Dirk; Kuzmenko, Alexey B

    2016-07-01

    We measure the far-infrared reflectivity and Kerr angle spectra on a high-quality crystal of pure semimetallic bismuth as a function of magnetic field, from which we extract the conductivity for left- and right-handed circular polarizations. The high spectral resolution allows us to separate the intraband Landau level transitions for electrons and holes. The hole transition exhibits 100% magnetic circular dichroism; it appears only for one polarization as expected for a circular cyclotron orbit. However, the dichroism for electron transitions is reduced to only 13±1%, which is quantitatively explained by the large effective mass anisotropy of the electron pockets of the Fermi surface. This observation is a signature of the mismatch between the metric experienced by the photons and the electrons. It allows for a contactless measurement of the effective mass anisotropy and provides a direction towards valley polarized magnetooptical pumping with elliptically polarized light. PMID:27419590

  20. Use of Chiral Signatures of Organochlorine Pesticides in Asian, Trans-Pacific, and Western U.S. Air Masses to Identify Source Regions

    NASA Astrophysics Data System (ADS)

    Simonich, S.; Genualdi, S.; Primbs, T.; Ryoo, K.; Bidleman, T.; Jantunen, L.

    2008-12-01

    Chiral signatures of organochlorine pesticides were measured in air masses on Okinawa Japan and three remote locations in the Pacific Northwestern U.S.: Cheeka Peak Observatory (CPO), a coastal site on the Olympic Peninsula of Washington at 500 m; Mary's Peak Observatory (MPO), a site at 1250 m in Oregon's Coast range; and Mt. Bachelor Observatory (MBO), a site at 2300 m in Oregon's Cascade range. The chiral signature of composite soil samples collected from agricultural areas in China and South Korea were also measured. Racemic alpha-HCH was measured in Asian air masses and soil from China and South Korea. Non-racemic (enantiomer fraction (EF) = 0.528 ± 0.0048) alpha-HCH was measured in regional air masses at CPO, a marine boundary layer site, and may reflect volatilization from the Pacific Ocean and regional soils. However, during trans-Pacific transport events at CPO, the EFs were significantly (p-value <0.001) more racemic (EF = 0.513 ± 0.0003). Racemic alpha-HCH was consistently measured in trans- Pacific air masses at MPO and MBO. The alpha-HCH EFs in CPO, MPO, and MBO air masses were positively correlated (p-value = 0.0017) with the amount of time the air mass spent above the boundary layer along the 10-day back air mass trajectory prior to being sampled. This suggests that the alpha-HCH in the free troposphere is racemic. The racemic signatures of cis and trans chlordane in air masses at all four air sampling sites suggest that Asian and U.S. urban areas continue to be sources of chlordanes that have not yet undergone biotransformation.

  1. Thermal desorption-gas chromatography-mass spectrometry method to determine phthalate and organophosphate esters from air samples.

    PubMed

    Aragón, M; Borrull, F; Marcé, R M

    2013-08-16

    A method based on thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed to determine four organophosphate esters, seven phthalate esters, and bis(2-ethylhexyl) adipate in the gas phase from harbour and urban air samples. The method involves the sampling of 1.5L of air in a Tenax TA sorbent tube followed by thermal desorption (using a Tenax TA cryogenic trap) coupled to gas chromatography-mass spectrometry. The repeatability of the method expressed as %RSD (n=3) is less than 15% and the MQLs are between 0.007μgm(-3) (DMP, TBP, BBP, TPP and DnOP) and 6.7μgm(-3) (DEHP). The method was successfully applied in two areas (urban and harbour) testing two and three points in each one, respectively. Some of these compounds were found in both urban and harbour samples. Di-(2-ethylhexyl)phthalate was the most abundant compound found in both areas at concentration levels between 6.7μgm(-3) and 136.4μgm(-3). This study demonstrates that thermal desorption is an efficient method for the determination of these semi-volatile compounds in the gas phase fraction of air samples. PMID:23859797

  2. Retrospective screening of pesticide metabolites in ambient air using liquid chromatography coupled to high-resolution mass spectrometry.

    PubMed

    López, Antonio; Yusà, Vicent; Millet, Maurice; Coscollà, Clara

    2016-04-01

    A new methodology for the retrospective screening of pesticide metabolites in ambient air was developed, using liquid chromatography coupled to Orbitrap high-resolution mass spectrometry (UHPLC-HRMS), including two systematic workflows (i) post-run target screening (suspect screening) and (ii) non-target screening. An accurate-mass database was built and used for the post-run screening analysis. The database contained 240 pesticide metabolites found in different matrixes such as air, soil, water, plants, animals and humans. For non-target analysis, a "fragmentation-degradation" relationship strategy was selected. The proposed methodology was applied to 31 air samples (PM10) collected in the Valencian Region (Spain). In the post-target analysis 34 metabolites were identified, of which 11 (3-ketocarburan, carbofuran-7-phenol, carbendazim, desmethylisoproturon, ethiofencarb-sulfoxide, malaoxon, methiocarb-sulfoxide, N-(2-ethyl-6-methylphenyl)-L-alanine, omethoate, 2-hydroxy-terbuthylazine, and THPAM) were confirmed using analytical standards. The semiquantitative estimated concentration ranged between 6.78 and 198.31 pg m(-3). Likewise, two unknown degradation products of malaoxon and fenhexamid were elucidated in the non-target screening. PMID:26838378

  3. An automated gas chromatography time-of-flight mass spectrometry instrument for the quantitative analysis of halocarbons in air

    NASA Astrophysics Data System (ADS)

    Obersteiner, F.; Bönisch, H.; Engel, A.

    2016-01-01

    We present the characterization and application of a new gas chromatography time-of-flight mass spectrometry instrument (GC-TOFMS) for the quantitative analysis of halocarbons in air samples. The setup comprises three fundamental enhancements compared to our earlier work (Hoker et al., 2015): (1) full automation, (2) a mass resolving power R = m/Δm of the TOFMS (Tofwerk AG, Switzerland) increased up to 4000 and (3) a fully accessible data format of the mass spectrometric data. Automation in combination with the accessible data allowed an in-depth characterization of the instrument. Mass accuracy was found to be approximately 5 ppm in mean after automatic recalibration of the mass axis in each measurement. A TOFMS configuration giving R = 3500 was chosen to provide an R-to-sensitivity ratio suitable for our purpose. Calculated detection limits are as low as a few femtograms by means of the accurate mass information. The precision for substance quantification was 0.15 % at the best for an individual measurement and in general mainly determined by the signal-to-noise ratio of the chromatographic peak. Detector non-linearity was found to be insignificant up to a mixing ratio of roughly 150 ppt at 0.5 L sampled volume. At higher concentrations, non-linearities of a few percent were observed (precision level: 0.2 %) but could be attributed to a potential source within the detection system. A straightforward correction for those non-linearities was applied in data processing, again by exploiting the accurate mass information. Based on the overall characterization results, the GC-TOFMS instrument was found to be very well suited for the task of quantitative halocarbon trace gas observation and a big step forward compared to scanning, quadrupole MS with low mass resolving power and a TOFMS technique reported to be non-linear and restricted by a small dynamical range.

  4. Air mass origin and its influence on radionuclide activities ( 7Be and 210Pb) in aerosol particles at a coastal site in the western Mediterranean

    NASA Astrophysics Data System (ADS)

    Dueñas, C.; Orza, J. A. G.; Cabello, M.; Fernández, M. C.; Cañete, S.; Pérez, M.; Gordo, E.

    2011-07-01

    Studies of radionuclide activities in aerosol particles provide a means for evaluating the integrated effects of transport and meteorology on the atmospheric loadings of substances with different sources. Measurements of aerosol mass concentration and specific activities of 7Be and 210Pb in aerosols at Málaga (36° 43' 40″ N; 4° 28' 8″ W) for the period 2000-2006 were used to obtain the relationships between radionuclide activities and airflow patterns by comparing the data grouped by air mass trajectory clusters. The average concentration values of 7Be and 210Pb over the 7 year period have been found to be 4.6 and 0.58 mBq m -3, respectively, with mean aerosol mass concentration of 53.6 μg m -3. The identified air flow types arriving at Málaga reflect the transitional location of the Iberian Peninsula and show significant differences in radionuclide activities. Air concentrations of both nuclides and the aerosol mass concentration are controlled predominantly by the synoptic scenarios leading to the entrance of dust-laden continental flows from northern Africa and the arrival of polar maritime air masses, as implied by the strong correlations found between the monthly frequencies of the different air masses and the specific activities of both radionuclides. Correlations between activity concentrations and precipitation are significant though lower than with air masses.

  5. Climatological classification of five sectors in the Iberian Peninsula using columnar (AOD, α) and surface (PM10, PM2.5) aerosol data supported by air mass apportioning

    NASA Astrophysics Data System (ADS)

    Cachorro, Victoria; Mateos, David; Toledano, Carlos; Burgos, Maria A.; Bennouna, Yasmine; Torres, Benjamín; Fuertes, David; González, Ramiro; Guirado, Carmen; Román, Roberto; Velasco-Merino, Cristian; Marcos, Alberto; Calle, Abel; de Frutos, Angel M.

    2015-04-01

    The study of atmospheric aerosol over the Iberian Peninsula (IP) under a climatologic perspective is an interesting and meaningful aim due to the wide variety of conditions (geographical position, air masses, topography, among others) which cause a complex role of the distribution of aerosol properties. In the deeply investigation on the annual cycle and time evolution of the particulate matter lower than 10 µm (PM10, surface) and aerosol optical depth (AOD, columnar) in a large number of sites covering the period 2000-2013, five sectors can be distinguished in the IP. Both set of data belong to EMEP and AERONET networks respectively, as representative of aerosol air quality and climate studies, are complementary elements for a global aerosol research. The prevalence of fine-coarse particles is also analyzed over each sector. Seasonal bimodality of the PM10 annual cycle with a strong North-South gradient is observed in most sites, but this is only reported in the AOD climatology for the southern IP. The northern coast is clearly governed by the Atlantic Ocean influence, while the northeastern area is modulated by the Mediterranean Sea. The southern area, very close to the African continent, presents a large influence of desert dust intrusions. However, the southern Atlantic and Mediterranean coast present discrepancies and two sectors have been defined in this area. Finally, the center of the Peninsula is a mix of conditions, with north-south and east-west gradients of different magnitude. Overall, there is a relationship between PM10 and AOD with a proportional factor varying from 20 to 90, depending on the sector. The particular characteristic of PM10-AOD annual cycle of each geographical sector can be understood by the different climatology of the air mass origins observed at 500 and 1500 m (a.s.l.) and its apportioning to PM10 and AOD, respectively.

  6. Petroleum mass removal from low permeability sediment using air sparging/soil vapor extraction: impact of continuous or pulsed operation

    NASA Astrophysics Data System (ADS)

    Kirtland, Brian C.; Aelion, C. Marjorie

    2000-02-01

    Air sparging and soil vapor extraction (AS/SVE) are innovative remediation techniques that utilize volatilization and microbial degradation to remediate petroleum spills from soils and groundwater. This in situ study investigated the use of AS/SVE to remediate a gasoline spill from a leaking underground storage tank (UST) in the low permeability, clayey soil of the Appalachian Piedmont. The objectives of this study were to evaluate AS/SVE in low permeability soils by quantifying petroleum mass removal rates, monitoring vadose zone contaminant levels, and comparing the mass extraction rates of continuous AS/SVE to 8 and 24 h pulsed operation. The objectives were met by collecting AS/SVE exhaust gas samples and vadose zone air from multi-depth soil vapor probes. Samples were analyzed for O 2, CO 2, BTEX (benzene, toluene, ethylbenzene, xylene), and total combustible hydrocarbon (TCH) concentrations using portable hand meters and gas chromatography. Continuous AS/SVE was effective in removing 608 kg of petroleum hydrocarbons from low permeability soil in 44 days (14.3 kg day -1). Mass removal rates ranged from 2.6 times higher to 5.1 times lower than other AS/SVE studies performed in sandy sediments. BTEX levels in the vadose zone were reduced from about 5 ppm to 1 ppm. Ten pulsed AS/SVE tests removed 78 kg in 23 days and the mean mass removal rate (17.6 kg day -1) was significantly higher than the last 15 days of continuous extraction. Pulsed operation may be preferable to continuous operation because of increased mass removal and decreased energy consumption.

  7. [Determination of volatile organic compounds in ambient air by thermal desorption-gas chromatography-triple quadrupole tandem mass spectrometry].

    PubMed

    Feng, Lili; Hu, Xiaofang; Yu, Xiaojuan; Zhang, Wenying

    2016-02-01

    A method was established for the simultaneous determination of 23 volatile organic compounds (VOCs) in ambient air with combination of thermal desorption (TD) and gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS). The air samples were collected by active sampling method using Tenax-TA sorbent tubes, and desorbed by thermal desorption. The analytes were determined by GC-MS/MS in selected reaction monitoring (SRM) mode, and internal standard method was applied to quantify the VOCs. The results of all the 23 VOCs showed good linearities in low level (0. 01-1 ng) and high level (1-100 ng) with all the correlation coefficients (r2) more than 0. 99. The method quantification limits were between 0. 000 08-1 µg/m3. The method was validated by means of recovery experiments (n = 6) at three spiked levels of 2, 10 and 50 ng. The recoveries between 77% and 124% were generally obtained. The relative standard deviations (RSDs) in all cases were lower than 20%, except for chlorobenzene at the low spiked level. The developed method was applied to determine VOCs in ambient air collected at three sites in Shanghai. Several compounds, like benzene, toluene, ethylbenzene, m-xylenes, p-xylenes, styrene, 1, 2, 4-trimethylbenzene and hexachlorobutadiene were detected and confirmed in all the samples analyzed. The method is highly accurate, reliable and sensitive for monitoring the VOCs in ambient air. PMID:27382728

  8. Measurement of volatile plant compounds in field ambient air by thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Cai, Xiao-Ming; Xu, Xiu-Xiu; Bian, Lei; Luo, Zong-Xiu; Chen, Zong-Mao

    2015-12-01

    Determination of volatile plant compounds in field ambient air 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-gas chromatography-mass spectrometry (TD-GC-MS) method was developed to measure ultra-trace levels of volatile plant compounds in field ambient air. 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 air. 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 concentrations 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 air. PMID:26493981

  9. Earthquake response reduction of mid-story isolated system due to semi-active control using magnetorheological rotary inertia mass damper

    NASA Astrophysics Data System (ADS)

    Ito, Mai; Yoshida, Shohei; Fujitani, Hideo; Sato, Yusuke

    2015-04-01

    The dynamic characteristics of mid-story isolated buildings and seismic response reduction due to a semi-active control system were investigated using a three-lumped-mass model that simplified the sixteen story building with an isolation layer in the sixth story. A semi-active control method using a rotary inertia mass damper filled with magnetorheological fluid (MR fluid) was proposed. The damper shows both mass amplification effect due to rotational inertia and variable damping effect due to the MR fluid. The damping force is controlled by the strength of the magnetic field that is applied to the MR fluid. It is determined by using the electric current, which is calculated by the proposed semi-active control method based on the velocity of the isolation layer relative to the layer just underneath it. Real-time hybrid tests using an actual damper and simulations using a building model were conducted to check the damper model; the test results were in good agreement with the simulation results. The simulation results suggest that the response displacement of the structure above the isolation layer is significantly reduced, without increasing the response acceleration of the entire structure against near-fault pulse and long-period ground motions. The proposed semi-active control using an MR rotary inertia mass damper was confirmed to be effective for mid-story isolated buildings.

  10. Modeling 3D conjugate heat and mass transfer for turbulent air drying of Chilean papaya in a direct contact dryer

    NASA Astrophysics Data System (ADS)

    Lemus-Mondaca, Roberto A.; Vega-Gálvez, Antonio; Zambra, Carlos E.; Moraga, Nelson O.

    2016-03-01

    A 3D model considering heat and mass transfer for food dehydration inside a direct contact dryer is studied. The k- ɛ model is used to describe turbulent air flow. The samples thermophysical properties as density, specific heat, and thermal conductivity are assumed to vary non-linearly with temperature. FVM, SIMPLE algorithm based on a FORTRAN code are used. Results unsteady velocity, temperature, moisture, kinetic energy and dissipation rate for the air flow are presented, whilst temperature and moisture values for the food also are presented. The validation procedure includes a comparison with experimental and numerical temperature and moisture content results obtained from experimental data, reaching a deviation 7-10 %. In addition, this turbulent k- ɛ model provided a better understanding of the transport phenomenon inside the dryer and sample.

  11. Bias in the prediction of genetic gain due to mass and half-sib selection in random mating populations

    PubMed Central

    2009-01-01

    The prediction of gains from selection allows the comparison of breeding methods and selection strategies, although these estimates may be biased. The objective of this study was to investigate the extent of such bias in predicting genetic gain. For this, we simulated 10 cycles of a hypothetical breeding program that involved seven traits, three population classes, three experimental conditions and two breeding methods (mass and half-sib selection). Each combination of trait, population, heritability, method and cycle was repeated 10 times. The predicted gains were biased, even when the genetic parameters were estimated without error. Gain from selection in both genders is twice the gain from selection in a single gender only in the absence of dominance. The use of genotypic variance or broad sense heritability in the predictions represented an additional source of bias. Predictions based on additive variance and narrow sense heritability were equivalent, as were predictions based on genotypic variance and broad sense heritability. The predictions based on mass and family selection were suitable for comparing selection strategies, whereas those based on selection within progenies showed the largest bias and lower association with the realized gain. PMID:21637512

  12. Continental Land Mass Air Traffic Control (COLM ATC). [using three artificial satellite configurations

    NASA Technical Reports Server (NTRS)

    Pecar, J. A.; Henrich, J. E.

    1973-01-01

    The application of various satellite systems and techniques relative to providing air traffic control services for the continental United States was studied. Three satellite configurations were reviewed. The characteristics and capabilities of the satellites are described. The study includes consideration for the various ranging waveforms, multiple access alternatives, and the power and bandwidth required as a function of the number of users.

  13. Resonance-mode effect on microcantilever mass-sensing performance in air.

    PubMed

    Xia, Xiaoyuan; Li, Xinxin

    2008-07-01

    This research investigates the air drag damping effect of the micromachined cantilevers in different resonance modes on the quality factor, which are operated in ambient air. Based on a simplified dish-string model for air drag force acting on the resonant cantilever, the air drag damping properties of the cantilevers vibrating in different modes are analyzed with theoretic vibration mechanics, which is complemented and further confirmed with finite-element simulation. Four kinds of integrated cantilevers, which resonate in the first flexural mode, the second flexural mode, the first torsional mode, and the second torsional mode, respectively, are designed and fabricated by using micromachining techniques. Finally, biomolecular sensing experiments are carried out to verify the theoretical results obtained before. From both the modeling and experimental results, it can be seen that damping characteristics of the torsional cantilever resonators are generally better than that of the flexural ones, and quality factor of the cantilever resonator in a higher-frequency mode is always superior to that in a lower-frequency one. Among the four kinds of microcantilever resonators operated in our experiments, the one operated in the second flexural modes exhibits the highest Q factor and the best biomass sensing performance. PMID:18681721

  14. Resonance-mode effect on microcantilever mass-sensing performance in air

    SciTech Connect

    Xia Xiaoyuan; Li Xinxin

    2008-07-15

    This research investigates the air drag damping effect of the micromachined cantilevers in different resonance modes on the quality factor, which are operated in ambient air. Based on a simplified dish-string model for air drag force acting on the resonant cantilever, the air drag damping properties of the cantilevers vibrating in different modes are analyzed with theoretic vibration mechanics, which is complemented and further confirmed with finite-element simulation. Four kinds of integrated cantilevers, which resonate in the first flexural mode, the second flexural mode, the first torsional mode, and the second torsional mode, respectively, are designed and fabricated by using micromachining techniques. Finally, biomolecular sensing experiments are carried out to verify the theoretical results obtained before. From both the modeling and experimental results, it can be seen that damping characteristics of the torsional cantilever resonators are generally better than that of the flexural ones, and quality factor of the cantilever resonator in a higher-frequency mode is always superior to that in a lower-frequency one. Among the four kinds of microcantilever resonators operated in our experiments, the one operated in the second flexural modes exhibits the highest Q factor and the best biomass sensing performance.

  15. Aerosol composition and properties variation at the ground and over the column under different air masses advection in South Italy.

    PubMed

    Pavese, G; Lettino, A; Calvello, M; Esposito, F; Fiore, S

    2016-04-01

    Aerosol composition and properties variation under the advection of different air masses were investigated, as case studies, by contemporary measurements over the atmospheric column and at the ground in a semi-rural site in South Italy. The absence of local strong sources in this area allowed to characterize background aerosol and to compare particle mixing effects under various atmospheric circulation conditions. Aerosol optical depth (AOD) and Ǻngström parameters from radiometric measurements allowed the detection and identification of polluted, dust, and volcanic atmospheric conditions. AODs were the input for a suitable model to evaluate the columnar aerosol composition, according to six main atmospheric components (water-soluble, soot, sea salt accumulation, sea salt coarse, mineral dus,t and biological). Scanning electron microscope (SEM) analysis of particulate sampled with a 13-stage impactor at the ground showed not only fingerprints typical of the different air masses but also the effects of transport and aging on atmospheric particles, suggesting processes that changed their chemical and optical properties. Background columnar aerosol was characterized by 72% of water-soluble and soot, in agreement with ground-based findings that highlighted 60% of contribution from anthropogenic carbonate particles and soot. In general, a good agreement between ground-based and columnar results was observed. Under the advection of trans-boundary air masses, water-soluble and soot were always present in columnar aerosol, whereas, in variable percentages, sea salt and mineral particles characterized both dust and volcanic conditions. At the ground, sulfates characterized the amorphous matrix produced in finer stages by the evaporation of solutions of organic and inorganic aerosols. Sulfates were also one of the key players involved in heterogeneous chemical reactions, producing complex secondary aerosol, as such clay-sulfate internally mixed particle externally mixed

  16. Detection of biological particles in ambient air using bio-aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    McJimpsey, Erica L.; Steele, Paul T.; Coffee, Keith R.; Fergenson, David P.; Riot, Vincent J.; Woods, Bruce W.; Gard, Eric E.; Frank, Matthias; Tobias, Herbert J.; Lebrilla, Carlito

    2006-05-01

    The Bio-Aerosol Mass Spectrometry (BAMS) system is an instrument used for the real time detection and identification of biological aerosols. Particles are drawn from the atmosphere directly into vacuum and tracked as they scatter light from several continuous wave lasers. After tracking, the fluorescence of individual particles is excited by a pulsed 266nm or 355nm laser. Molecules from those particles with appropriate fluorescence properties are subsequently desorbed and ionized using a pulsed 266nm laser. Resulting ions are analyzed in a dual polarity mass spectrometer. During two field deployments at the San Francisco International Airport, millions of ambient particles were analyzed and a small but significant fraction were found to have fluorescent properties similar to Bacillus spores and vegetative cells. Further separation of non-biological background particles from potential biological particles was accomplished using laser desorption/ionization mass spectrometry. This has been shown to enable some level of species differentiation in specific cases, but the creation and observation of higher mass ions is needed to enable a higher level of specificity across more species. A soft ionization technique, matrix-assisted laser desorption/ionization (MALDI) is being investigated for this purpose. MALDI is particularly well suited for mass analysis of biomolecules since it allows for the generation of molecular ions from large mass compounds that would fragment under normal irradiation. Some of the initial results from a modified BAMS system utilizing this technique are described.

  17. Detection of biological particles in ambient air using Bio-Aerosol Mass Spectrometry

    SciTech Connect

    McJimpsey, E L; Steele, P T; Coffee, K R; Fergenson, D P; Riot, V J; Woods, B W; Gard, E E; Frank, M; Tobias, H J; Lebrilla, C

    2006-03-16

    The Bio-Aerosol Mass Spectrometry (BAMS) system is an instrument used for the real time detection and identification of biological aerosols. Particles are drawn from the atmosphere directly into vacuum and tracked as they scatter light from several continuous wave lasers. After tracking, the fluorescence of individual particles is excited by a pulsed 266nm or 355nm laser. Molecules from those particles with appropriate fluorescence properties are subsequently desorbed and ionized using a pulsed 266nm laser. Resulting ions are analyzed in a dual polarity mass spectrometer. During two field deployments at the San Francisco International Airport, millions of ambient particles were analyzed and a small but significant fraction were found to have fluorescent properties similar to Bacillus spores and vegetative cells. Further separation of non-biological background particles from potential biological particles was accomplished using laser desorption/ionization mass spectrometry. This has been shown to enable some level of species differentiation in specific cases, but the creation and observation of higher mass ions is needed to enable a higher level of specificity across more species. A soft ionization technique, matrix-assisted laser desorption/ionization (MALDI) is being investigated for this purpose. MALDI is particularly well suited for mass analysis of biomolecules since it allows for the generation of molecular ions from large mass compounds that would fragment under normal irradiation. Some of the initial results from a modified BAMS system utilizing this technique are described.

  18. Elemental composition and oxidative properties of PM(2.5) in Estonia in relation to origin of air masses - results from the ECRHS II in Tartu.

    PubMed

    Orru, Hans; Kimmel, Veljo; Kikas, Ulle; Soon, Argo; Künzli, Nino; Schins, Roel P F; Borm, Paul J A; Forsberg, Bertil

    2010-03-01

    Fine particulate matter (PM(2.5)) was sampled at an urban background site in Tartu, Estonia over one-year period during the ECRHS II study. The elemental composition of 71 PM(2.5) samples was analyzed for different chemical elements using energy-dispersive X-ray fluorescence spectrometry (ED-XRF). The oxidative activity of 36 samples was assessed by measuring their ability to generate hydroxyl radicals in the presence of hydrogen peroxide. The origin of air masses was determined by computing 96-hour back trajectories of air masses with the HYSPLIT Model. The trajectories of air masses were divided into four sectors according to geographical patterns: "Russia," "Eastern Europe," "Western Europe," and "Scandinavia." During the study period, approximately 30% of air masses originated from "Scandinavia." The other three sectors had slightly lower values (between 18 and 22%). In spring, summer, and winter, higher total PM levels originated from air masses from continental areas, namely "Russia" and "Eastern Europe" (18.51+/-7.33 and 19.96+/-9.23microg m(-3), respectively). In autumn, the PM levels were highest in "Western Europe". High levels of Fe, Ti, and AlCaSi (Al, Ca, and Si) were also detected in air masses from the Eurasian continent. The oxidative properties were correlated to the origin of air masses. The OH values were approximately 1.5 times higher when air masses originated from the direction of "Eastern Europe" or "Russia." The origin of measured particles was evaluated using principal component factor analysis. When comparing the PM(2.5) elemental composition with seasonal variation, factor scores, and other studies, the factors represent: (1) combustion of biomass; (2) crustal dust; (3) traffic; and (4) power plants and industrial processes associated with oil burning. The total PM(2.5) is driven mainly by biomass and industrial combustion (63%) and other unidentified sources (23%). Other sources of PM, such as crustal dust and traffic, contribute a total

  19. Generalized solution for 1-D non-Newtonian flow in a porous domain due to an instantaneous mass injection

    NASA Astrophysics Data System (ADS)

    Di Federico, V.; Ciriello, V.

    2011-12-01

    Non-Newtonian fluid flow in porous media is of considerable interest in hydrology, chemical and petroleum engineering, and biofluid mechanics. We consider an infinite porous domain of plane (d=1), cylindrical (d=2) or semi-spherical geometry (d=3), having uniform permeability k and porosity Φ, initially at uniform pressure and saturated by a weakly compressible non-Newtonian fluid, and analyze the dynamics of the pressure variation generated within the domain by an instantaneous mass injection m0 in its origin. The fluid is described by a rheological power-law model of given consistency index H and flow behavior index n; the flow law is a modified Darcy's law depending on H, Φ, n. Coupling flow law and mass balance equations yields the nonlinear partial differential equation governing the pressure field; an analytical solution is derived in space r and time t as a function of a self-similar variable η=r/tβ(n). We revisit and expand the work in previous papers by providing a dimensionless general formulation and solution to the problem for d=1,2,3. When a shear-thinning fluid (n<1) is considered, the analytical solution exhibits traveling wave characteristics, in variance with Newtonian fluids; the front velocity is proportional to t(n-2)/2 in plane geometry, t(2n-3)/(3-n) in cylindrical geometry, and t(3n-4)/(4-2n) in semi-spherical geometry. The front position is a markedly increasing function of n and is inversely dependent on d; the pressure front advances at a slower rate for larger values of compressibility, higher injected mass and lower porosity. When pressure is considered, it is seen that an increase in d from 1 to 3 brings about an order of magnitude reduction. An increase in compressibility implies a significant decrease in pressure, especially at early times. To reflect the uncertainty inherent in values of the problem parameters, we then consider selected properties of fluid (flow behavior index n) and porous domain (permeability k, porosity

  20. Natural convection flows due to the combined buoyancy of heat and mass diffusion in a thermally stratified medium

    SciTech Connect

    Angirasa, D.; Srinivasan, J. )

    1989-08-01

    This paper presents a numerical study of laminar doubly diffusive free convection flows adjacent to a vertical surface in a stable thermally stratified medium. The two buoyant mechanisms are thermal diffusion and species diffusion. The species concentration is assumed to be small. Boussinesq approximations are incorporated and the governing conservation equations of mass, momentum, energy, and species are nondimensionalized. These equations are solved using a finite-difference method. The results are explained in terms of the basic physical mechanisms that govern these flows. It is observed that the ambient thermal stratification has a profound influence on the transport characteristics. The results show many interesting aspects of the complex interaction of the two buoyant mechanisms.

  1. High-efficiency, one-sun (22. 3% at air mass 0; 23. 9% at air mass 1. 5) monolithic two-junction cascade solar cell grown by metalorganic vapor phase epitaxy

    SciTech Connect

    Chung, B.; Virshup, G.F.; Werthen, J.G.

    1988-05-30

    A high-efficiency monolithic two-junction solar cell consisting of an Al/sub 0.37/Ga/sub 0.63/As (E/sub g/ = 1.93 eV) upper cell and a GaAs lower cell has been grown by metalorganic vapor phase epitaxy. Since both component cells have the n-on-p configuration, the unwanted p-n junction has been eliminated with the use of metal-interconnect contact during post-growth processing. As a two-terminal device, an efficiency of 22.3% has been achieved under 1 sun, air mass 0 illumination conditions, whereas an efficiency of 23.9% was obtained when the cascade cell was operated as a three-terminal device under 1 sun, air mass 1.5 illumination. This result represents the highest 1 sun efficiency ever reported. The advantages of utilizing this multijunction solar cell for terrestrial and space applications are also described.

  2. Plasma flame for mass purification of contaminated air with chemical and biological warfare agents

    SciTech Connect

    Uhm, Han S.; Shin, Dong H.; Hong, Yong C.

    2006-09-18

    An elimination of airborne simulated chemical and biological warfare agents was carried out by making use of a plasma flame made of atmospheric plasma and a fuel-burning flame, which can purify the interior air of a large volume in isolated spaces such as buildings, public transportation systems, and military vehicles. The plasma flame generator consists of a microwave plasma torch connected in series to a fuel injector and a reaction chamber. For example, a reaction chamber, with the dimensions of a 22 cm diameter and 30 cm length, purifies an airflow rate of 5000 lpm contaminated with toluene (the simulated chemical agent) and soot from a diesel engine (the simulated aerosol for biological agents). Large volumes of purification by the plasma flame will free mankind from the threat of airborne warfare agents. The plasma flame may also effectively purify air that is contaminated with volatile organic compounds, in addition to eliminating soot from diesel engines as an environmental application.

  3. Plasma flame for mass purification of contaminated air with chemical and biological warfare agents

    NASA Astrophysics Data System (ADS)

    Uhm, Han S.; Shin, Dong H.; Hong, Yong C.

    2006-09-01

    An elimination of airborne simulated chemical and biological warfare agents was carried out by making use of a plasma flame made of atmospheric plasma and a fuel-burning flame, which can purify the interior air of a large volume in isolated spaces such as buildings, public transportation systems, and military vehicles. The plasma flame generator consists of a microwave plasma torch connected in series to a fuel injector and a reaction chamber. For example, a reaction chamber, with the dimensions of a 22cm diameter and 30cm length, purifies an airflow rate of 5000lpm contaminated with toluene (the simulated chemical agent) and soot from a diesel engine (the simulated aerosol for biological agents). Large volumes of purification by the plasma flame will free mankind from the threat of airborne warfare agents. The plasma flame may also effectively purify air that is contaminated with volatile organic compounds, in addition to eliminating soot from diesel engines as an environmental application.

  4. Smart tetroons for Lagrangian air-mass tracking during ACE 1

    NASA Astrophysics Data System (ADS)

    Businger, Steven; Johnson, Randy; Katzfey, Jack; Siems, Steven; Wang, Qing

    1999-05-01

    A series of "smart" tetroons was released from shipboard during the recent ACE 1 field experiment designed to monitor changes in the sulfur budget in a remote marine boundary layer (MBL) south of Tasmania, Australia. The smart tetroons were designed at NOAA Air Resources Laboratory Field Research Division to provide air parcel tracking information. The adjective smart here refers here to the fact that the buoyancy of the tetroons automatically adjusts through the action of a pump and valves when the tetroon travels vertically outside a range of pressures set prior to tetroon release. The smart tetroon design provides GPS location, barometric pressure, temperature, relative humidity, and tetroon status data via a transponder to the NCAR C-130 research aircraft flying in the vicinity of the tetroons. In this paper we will describe (1) the design and capability of the smart tetroons and their performance during the two Lagrangian experiments conducted during ACE 1, (2) the synoptic context of the Lagrangians, including the origin of the air parcels being tracked, and (3) the results of trajectory predictions derived from the National Center for Environmental Prediction (NCEP) Global Spectral Model (GSM) and Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) Division of Atmospheric Research (DAR) limited-area model.

  5. Facility monitoring of chemical warfare agent simulants in air using an automated, field-deployable, miniature mass spectrometer.

    PubMed

    Smith, Jonell N; Noll, Robert J; Cooks, R Graham

    2011-05-30

    Vapors of four chemical warfare agent (CWA) stimulants, 2-chloroethyl ethyl sulfide (CEES), diethyl malonate (DEM), dimethyl methylphosphonate (DMMP), and methyl salicylate (MeS), were detected, identified, and quantitated using a fully automated, field-deployable, miniature mass spectrometer. Samples were ionized using a glow discharge electron ionization (GDEI) source, and ions were mass analyzed with a cylindrical ion trap (CIT) mass analyzer. A dual-tube thermal desorption system was used to trap compounds on 50:50 Tenax TA/Carboxen 569 sorbent before their thermal release. The sample concentrations ranged from low parts per billion [ppb] to two parts per million [ppm]. Limits of detection (LODs) ranged from 0.26 to 5.0 ppb. Receiver operating characteristic (ROC) curves are presented for each analyte. A sample of CEES at low ppb concentration was combined separately with two interferents, bleach (saturated vapor) and diesel fuel exhaust (1%), as a way to explore the capability of detecting the simulant in an environmental matrix. Also investigated was a mixture of the four CWA simulants (at concentrations in air ranging from 270 to 380 ppb). Tandem mass (MS/MS) spectral data were used to identify and quantify the individual components. PMID:21504010

  6. A practical approach to estimate emission rates of indoor air pollutants due to the use of personal combustible products based on small-chamber studies.

    PubMed

    Szulejko, Jan E; Kim, Ki-Hyun

    2016-02-01

    As emission rates of airborne pollutants are commonly measured from combusting substances placed inside small chambers, those values need to be re-evaluated for the possible significance under practical conditions. Here, a simple numerical procedure is investigated to extrapolate the chamber-based emission rates of formaldehyde that can be released from various combustible sources including e-cigarettes, conventional cigarettes, or scented candles to their concentration levels in a small room with relatively poor ventilation. This simple procedure relies on a mass balance approach by considering the masses of pollutants emitted from source and lost through ventilation under the assumption that mixing occurs instantaneously in the room without chemical reactions or surface sorption. The results of our study provide valuable insights into re-evaluation procedure of chamber data to allow comparison between extrapolated and recommended values to judge the safe use of various combustible products in confined spaces. If two scented candles with a formaldehyde emission rate of 310 µg h(-1) each were lit for 4 h in a small 20 m(3) room with an air change rate of 0.5 h(-1), then the 4-h (candle lit) and 8-h (up to 8 h after candle lighting) TWA [FA] were determined to be 28.5 and 23.5 ppb, respectively. This is clearly above the 8-h NIOSH recommended exposure limit (REL) time weighted average of 16 ppb. PMID:26495830

  7. Dependence of air masses type on PBL vertical structure retrieved at the Mace Head station during EUCAARI campaign.

    NASA Astrophysics Data System (ADS)

    Milroy, Conor; Martucci, Giovanni; O'Dowd, Colin

    2010-05-01

    During the EUCAARI Intensive Observing Period held at the Mace Head GAW station from mid-May to mid-June, 2008, the PBL depth has been continuously measured by two ceilometers (Vaisala CL31 and Jenoptik CHM15K) and a microwave radiometer (RPG-HATPRO). The Lidar-Ceilometer, through the gradients in aerosol backscatter profiles, and the microwave profiler, through gradients in the specific humidity profiles, were used to remotely-sense the boundary layer structure. An automatic, newly developed Temporal Height-Tracking (THT) algorithm (Martucci et al., 2010) have been applied to both type of instruments data to retrieve the 2-layered structure of the local marine boundary layer. The two layers are defined as a lower, well mixed layer, i.e. the surface mixed layer, and the layer occupying the region below the free Troposphere inversion, i.e. the decoupled residual or convective layer. A categorization of the incoming air masses has been performed based on their origins and been used to asses the correlation with the PBL depths. The study confirmed the dependence of PBL vertical structure on different air masses and different type of advected aerosol.

  8. Interaction of clothing and body mass index affects validity of air displacement plethysmography in adults

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: Examine the effect of alternate clothing schemes on validity of Bod Pod to estimate percent body fat (BF) compared to dual x-ray absorptiometry (DXA), and determine if these effects differ by body mass index (BMI). Design: Cross-sectional Subjects: 132 healthy adults aged 19-81 classifi...

  9. Mass transfer coefficients developed from the air gasification of wood pellets

    SciTech Connect

    Botts, J.W.

    1998-07-01

    A convertible updraft/downdraft, fixed-bed gasifier was used in the gasification of 3/8-inch diameter wood pellets. The test data was used to develop mass transfer coefficients and describe the gasification process for each gasifier configuration. The results show that the production of the principal combustion gases, i.e., hydrogen (H{sub c}), carbon monozide (CO), and methane (CH{sub 4}), varies directly as to their mass transfer coefficient: H{sub 2}, CO, and CH{sub 4} = k h{sub DA}. Factoring the Reynolds (Re{sub d}) and Schmidt (Sc) numbers with the influence of the noncombustible gases, i.e., nitrogen (N{sub 2}), oxygen (O{sub 2}), and carbon dioxide (CO{sub 2}), is used to define the mass transfer coefficients. The general form describing this joint variation is: H{sub 2}, CO, and CH{sub 4} = kx (the effect of the noncombustible gases) x Re x Sc where Re = Reynolds number and Sc = Schmidt number. The developments of these mass transfer coefficients are shown for updraft and downdraft gasification.

  10. Development and validation of a sensitive thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method for the determination of phosgene in air samples.

    PubMed

    Juillet, Y; Dubois, C; Bintein, F; Dissard, J; Bossée, A

    2014-08-01

    A new rapid, sensitive and reliable method was developed for the determination of phosgene in air samples using thermal desorption (TD) followed by gas chromatography-mass spectrometry (GC-MS). The method is based on a fast (10 min) active sampling of only 1 L of air 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 concentration ranges (0.04 to 2.5 ppmv and 2.5 to 10 ppmv) owing to variation of derivatization recovery between low and high concentration 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. PMID:24817348

  11. Non-spectral interferences due to the presence of sulfuric acid in inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    García-Poyo, M. Carmen; Grindlay, Guillermo; Gras, Luis; de Loos-Vollebregt, Margaretha T. C.; Mora, Juan

    2015-03-01

    Results of a systematic study concerning non-spectral interferences from sulfuric acid containing matrices on a large number of elements in inductively coupled plasma-mass spectrometry (ICP-MS) are presented in this work. The signals obtained with sulfuric acid solutions of different concentrations (up to 5% w w- 1) have been compared with the corresponding signals for a 1% w w- 1- nitric acid solution at different experimental conditions (i.e., sample uptake rates, nebulizer gas flows and r.f. powers). The signals observed for 128Te+, 78Se+ and 75As+ were significantly higher when using sulfuric acid matrices (up to 2.2-fold for 128Te+ and 78Se+ and 1.8-fold for 75As+ in the presence of 5 w w-1 sulfuric acid) for the whole range of experimental conditions tested. This is in agreement with previously reported observations. The signal for 31P+ is also higher (1.1-fold) in the presence of sulfuric acid. The signal enhancements for 128Te+, 78Se+, 75As+ and 31P+ are explained in relation to an increase in the analyte ion population as a result of charge transfer reactions involving S+ species in the plasma. Theoretical data suggest that Os, Sb, Pt, Ir, Zn and Hg could also be involved in sulfur-based charge transfer reactions, but no experimental evidence has been found. The presence of sulfuric acid gives rise to lower ion signals (about 10-20% lower) for the other nuclides tested, thus indicating the negative matrix effect caused by changes in the amount of analyte loading of the plasma. The elemental composition of a certified low-density polyethylene sample (ERM-EC681K) was determined by ICP-MS after two different sample digestion procedures, one of them including sulfuric acid. Element concentrations were in agreement with the certified values, irrespective of the acids used for the digestion. These results demonstrate that the use of matrix-matched standards allows the accurate determination of the tested elements in a sulfuric acid matrix.

  12. Observation by an air-shower array in Tibet of the multi-TeV cosmic-ray anisotropy due to terrestrial orbital motion around the Sun.

    PubMed

    Amenomori, M; Ayabe, S; Cui, S W; Danzengluobu; Ding, L K; Ding, X H; Feng, C F; Feng, Z Y; Gao, X Y; Geng, Q X; Guo, H W; He, H H; He, M; Hibino, K; Hotta, N; Hu, Haibing; Hu, H B; Huang, J; Huang, Q; Jia, H Y; Kajino, F; Kasahara, K; Katayose, Y; Kato, C; Kawata, K; Labaciren; Le, G M; Li, J Y; Lu, H; Lu, S L; Meng, X R; Mizutani, K; Mori, S; Mu, J; Munakata, K; Nanjo, H; Nishizawa, M; Ohnishi, M; Ohta, I; Onuma, H; Ouchi, T; Ozawa, S; Ren, J R; Saito, T; Sakata, M; Sasaki, T; Shibata, M; Shiomi, A; Shirai, T; Sugimoto, H; Takita, M; Tan, Y H; Tateyama, N; Torii, S; Tsuchiya, H; Udo, S; Utsugi, T; Wang, B S; Wang, H; Wang, X; Wang, Y G; Wu, H R; Xue, L; Yamamoto, Y; Yan, C T; Yang, X C; Yasue, S; Ye, Z H; Yu, G C; Yuan, A F; Yuda, T; Zhang, H M; Zhang, J L; Zhang, N J; Zhang, X Y; Zhang, Y; Zhaxisangzhu; Zhou, X X

    2004-08-01

    We report on the solar diurnal variation of the galactic cosmic-ray intensity observed by the Tibet III air shower array during the period from 1999 to 2003. In the higher-energy event samples (12 and 6.2 TeV), the variations are fairly consistent with the Compton-Getting anisotropy due to the terrestrial orbital motion around the Sun, while the variation in the lower-energy event sample (4.0 TeV) is inconsistent with this anisotropy. This suggests an additional anisotropy superposed at the multi-TeV energies, e.g., the solar modulation effect. This is the highest-precision measurement of the Compton-Getting anisotropy ever made. PMID:15323615

  13. Causes, Dynamics and Impacts of Lahar Mass Flows due to the April 2015 Eruption of Calbuco Volcano, Chile

    NASA Astrophysics Data System (ADS)

    Dussaillant, Alejandro; Russell, Andy; Meier, Claudio; Rivera, Andres; Mella, Mauricio; Garrido, Natalia; Hernandez, Jorge; Napoleoni, Felipe; Gonzalez, Cristian

    2016-04-01

    provides large volumes of sediment to distal portions of fluvial systems radiating from Calbuco, continuing impact on infrastructure and settlements, including secondary lahars due to rain and melt events. The database generated by this study hopes to contribute to further studies into lahars, including its use to test lahar numerical models.

  14. Distortion of thermospheric air masses by horizontal neutral winds over Poker Flat Alaska measured using an all-sky scanning Doppler imager

    NASA Astrophysics Data System (ADS)

    Dhadly, M. S.; Conde, M.

    2016-01-01

    An air mass transported by a wind field will become distorted over time by any gradients present in the wind field. To study this effect in Earth's thermosphere, we examine the behavior of a simple parameter that we describe here as the "distortion gradient." It incorporates all of the wind field's departures from uniformity and is thus capable of representing all contributions to the distortion or mixing of air masses. The distortion gradient is defined such that it is always positive, so averaging over time and/or space does not suppress small-scale features. Conventional gradients, by contrast, are signed quantities that would often average to zero. To analyze the climatological behavior of this distortion gradient, we used three years (2010, 2011, and 2012) of thermospheric F region wind observations from a high-latitude ground-based all-sky wavelength scanning Doppler Fabry-Perot interferometer located at Poker Flat Alaska. Climatological averaging of the distortion gradient allowed us to investigate its diurnal and seasonal (annual) behaviors at our observing location. Distortion was observed to be higher before local magnetic midnight and to be seasonally dependent. While maximum distortion occurred before local magnetic midnight under all geomagnetic conditions, the peak distortion occurred earlier under moderate geomagnetic conditions as compared to the quiet geomagnetic conditions and even earlier still when geomagnetic conditions were active. Peak distortion was stronger and appeared earlier when interplanetary magnetic field (IMF) was southward compared to northward. By contrast, we could not resolve any time-shift effect due to the IMF component tangential to Earth's orbit.

  15. Air-sea fluxes and satellite-based estimation of water masses formation

    NASA Astrophysics Data System (ADS)

    Sabia, Roberto; Klockmann, Marlene; Fernandez-Prieto, Diego; Donlon, Craig

    2015-04-01

    Recent work linking satellite-based measurements of sea surface salinity (SSS) and sea surface temperature (SST) with traditional physical oceanography has demonstrated the capability of generating routinely satellite-derived surface T-S diagrams [1] and analyze the distribution/dynamics of SSS and its relative surface density with respect to in-situ measurements. Even more recently [2,3], this framework has been extended by exploiting these T-S diagrams as a diagnostic tool to derive water masses formation rates and areas. A water mass describes a water body with physical properties distinct from the surrounding water, formed at the ocean surface under specific conditions which determine its temperature and salinity. The SST and SSS (and thus also density) at the ocean surface are largely determined by fluxes of heat and freshwater. The surface density flux is a function of the latter two and describes the change of the density of seawater at the surface. To obtain observations of water mass formation is of great interest, since they serve as indirect observations of the thermo-haline circulation. The SSS data which has become available through the SMOS [4] and Aquarius [5] satellite missions will provide the possibility of studying also the effect of temporally-varying SSS fields on water mass formation. In the present study, the formation of water masses as a function of SST and SSS is derived from the surface density flux by integrating the latter over a specific area and time period in bins of SST and SSS and then taking the derivative of the total density flux with respect to density. This study presents a test case using SMOS SSS, OSTIA SST, as well as Argo ISAS SST and SSS for comparison, heat fluxes from the NOCS Surface Flux Data Set v2.0, OAFlux evaporation and CMORPH precipitation. The study area, initially referred to the North Atlantic, is extended over two additional ocean basins and the study period covers the 2011-2012 timeframe. Yearly, seasonal

  16. Determination of fragrance allergens in indoor air by active sampling followed by ultrasound-assisted solvent extraction and gas chromatography-mass spectrometry.

    PubMed

    Lamas, J Pablo; Sanchez-Prado, Lucia; Garcia-Jares, Carmen; Llompart, Maria

    2010-03-19

    Fragrances are ubiquitous pollutants in the environment, present in the most of household products, air fresheners, insecticides and cosmetics. Commercial perfumes may contain hundreds of individual fragrance chemicals. In addition to the widespread use and exposure to fragranced products, many of the raw fragrance materials have limited available health and safety data. Because of their nature as artificial fragrances, inhalation should be considered as an important exposure pathway, especially in indoor environments. In this work, a very simple, fast, and sensitive methodology for the analysis of 24 fragrance allergens in indoor air is presented. Considered compounds include those regulated by the EU Directive, excluding limonene; methyl eugenol was also included due to its toxicity. The proposed methodology is based on the use of a very low amount of adsorbent to retain the target compounds, and the rapid ultrasound-assisted solvent extraction (UAE) using a very low volume of solvent which avoids further extract concentration. Quantification was performed by gas chromatography coupled to mass spectrometry (GC-MS). The influence of main factors involved in the UAE step (type of adsorbent and solvent, solvent volume and extraction time) was studied using an experimental design approach to account for possible factor interactions. Using the optimized procedure, 0.2 m(-3) air are sampled, analytes are retained on 25 mg Florisil, from which they are extracted by UAE (5 min) with 2 mL ethyl acetate. Linearity was demonstrated in a wide concentration range. Efficiency of the total sampling-extraction process was studied at several concentration levels (1, 5 and 125 microg m(-3)), obtaining quantitative recoveries, and good precision (RSD<10%). Method detection limits were < or =0.6 microg m(-3). Finally, the proposed method was applied to real samples collected in indoor environments in which several of the target compounds were determined. PMID:20138288

  17. What is the role of wind pumping on heat and mass transfer rates at the air-snow interface?

    NASA Astrophysics Data System (ADS)

    Helgason, W.; Pomeroy, J. W.

    2010-12-01

    Accurate prediction of the turbulent exchange of sensible heat and water vapour between the atmosphere and snowpack remains a challenging task under all but the most ideal conditions. Heat and mass transfer coefficients that recognize the unique properties of the snow surface are warranted. A particular area requiring improvement concerns the role of the porous nature of snow which provides a large surface area for heat and mass exchange with the atmosphere. Wind-pumping has long been considered as a viable mechanism for incorporating aerosols into snowpacks; however these processes are not considered in parameterization schemes for heat and mass transfer near the surface. This study attempts to determine the degree to which wind pumping can increase the rates of heat and mass transfer to snow, and to ascertain which structural properties of the snowpack are needed for inclusion in heat and mass transfer coefficients that reflect wind pumping processes. Based upon a review of recent geophysical and engineering literature where porous surfaces are exploited for their ability to augment heat and mass transfer rates, a technical analysis was conducted. Numerous conceptual mechanisms of wind pumping were considered: topographically-induced flow; barometric pressure changes; high frequency pressure fluctuations at the surface; and steady flow in the interfacial region. A sensitivity analysis was performed, subjecting each conceptual model to varying thermal and hydraulic conditions at the air-snow interface, as well as variable micro-structural properties of snow. It is shown that the rate of heat and mass exchange is most sensitive to the interfacial thermal conditions and factors controlling the energy balance of the uppermost snow grains. The effect upon the thermal regime of the snowpack was found to be most significant for mechanisms of wind pumping that result in shorter flow paths near the surface, rather than those caused by low frequency pressure changes. In

  18. Primary and secondary organic aerosols in urban air masses intercepted at a rural site

    NASA Astrophysics Data System (ADS)

    Liggio, John; Li, Shao-Meng; Vlasenko, Alexander; Sjostedt, Steve; Chang, Rachel; Shantz, Nicole; Abbatt, Jonathan; Slowik, J. G.; Bottenheim, J. W.; Brickell, P. C.; Stroud, C.; Leaitch, W. Richard

    2010-11-01

    Measurements made at a rural site in central Ontario during May-June 2007 are used to investigate the composition of organic aerosol (OA) downwind of an urban region. Observations of aerosol organic carbon and oxygen containing fragments from a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) are combined with toluene to benzene ratios to estimate the relative importance of secondary organic aerosol (SOA) and primary organic aerosol (POA) to the total OA at the site during periods of significant urban influence. We estimate that SOA formed within 1-2 days of the anthropogenic source regions was 40-50% of the measured OA and that POA was 5-16% of the OA. The remaining 35-45% of the OA is assumed to have been present in the aerosol upwind of the source regions prior to entering the study domain as defined by trajectories and estimates of the potential photochemical aging time. The apportionment results were also compared to that of positive matrix factorization analysis. In addition, the measurements of the molar oxygen to carbon ratio (O/C) in the OA demonstrates that SOA becomes progressively more oxygenated with increasing photochemical age and at low total OA mass.

  19. Interactions effectives, théories de champ moyen masses et rayons nucléaires

    NASA Astrophysics Data System (ADS)

    Meyer, J.

    2003-05-01

    Effective interactions, mean field theories, masses and nuclear radii A review of effective interactions used in mean field theories for the description of properties of atomic nuclei is presented. Relativistic as well as non relativistic theories are discussed with a special attention to the cases where their results are very different. We will concentrate on the effective forces built up to investigate the nuclear medium in extreme conditions. Masses and r.m.s. radii along long chain of isotopes will be discussed. Large deformations, as observed in the fission of heavy nuclei, and exotic neutron rich nuclei will be taken as examples of these extreme conditions. Le principal propos de cet ouvrage est : (i) de passer en revue les outils théoriques utilisés sous le sigle ”théories microscopiques de champ moyen ”. Sans entrer dans le détail des formalismes (le lecteur sera systématiquement renvoyé ”pour en savoir plus ” à des cours plus complets qui ont déjà été donnés dans le passé à l'École Joliot-Curie) il s'agira surtout de préciser le contexte, les hypothèses et les approximations qui se cachent sous les sigles : Hartree-Fock (HF), Hartree-Fock-Bogoliubov (HFB), Approximation BCS (HFBCS), Champ Moyen Relativiste (RMF), Approximations Hartree (RH), Hartree-Fock (RHF) et Hartree-Bogoliubov (RHB) Relativistes, ... ; (ii) de présenter la procédure générale et les ingrédients qui entrent dans la construction d'une interaction effective, élément de base de ces théories dont l'intérêt majeur est de livrer des résultats comparables à l'expérience sans paramètre ajustable ; (iii) de discuter des effets des différentes approximations ou interactions effectives sur des résultats expérimentaux pris dans diverses zones de noyaux. Ces discussions seront surtout centrées sur les masses et les rayons des noyaux mais aussi sur certaines quantités plus significatives que l'on peut en extraire : énergies de séparation de deux neutrons

  20. Brief Communication: Upper-air relaxation in RACMO2 significantly improves modelled interannual surface mass balance variability in Antarctica

    NASA Astrophysics Data System (ADS)

    van de Berg, Willem Jan; Medley, Brooke

    2016-03-01

    The Regional Atmospheric Climate Model (RACMO2) has been a powerful tool for improving surface mass balance (SMB) estimates from GCMs or reanalyses. However, new yearly SMB observations for West Antarctica show that the modelled interannual variability in SMB is poorly simulated by RACMO2, in contrast to ERA-Interim, which resolves this variability well. In an attempt to remedy RACMO2 performance, we included additional upper-air relaxation (UAR) in RACMO2. With UAR, the correlation to observations is similar for RACMO2 and ERA-Interim. The spatial SMB patterns and ice-sheet-integrated SMB modelled using UAR remain very similar to the estimates of RACMO2 without UAR. We only observe an upstream smoothing of precipitation in regions with very steep topography like the Antarctic Peninsula. We conclude that UAR is a useful improvement for regional climate model simulations, although results in regions with steep topography should be treated with care.

  1. Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schindler, Matthias; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

    2016-05-01

    Three new methods to sample and prepare various carbonyl compounds for radiocarbon measurements were developed and tested. Two of these procedures utilized the Strecker synthetic method to form amino acids from carbonyl compounds with either sodium cyanide or trimethylsilyl cyanide. The third procedure used semicarbazide to form crystalline carbazones with the carbonyl compounds. The resulting amino acids and semicarbazones were then separated and purified using thin layer chromatography. The separated compounds were then combusted to CO2 and reduced to graphite to determine 14C content by accelerator mass spectrometry (AMS). All of these methods were also compared with the standard carbonyl compound sampling method wherein a compound is derivatized with 2,4-dinitrophenylhydrazine and then separated by high-performance liquid chromatography (HPLC).

  2. Measurement error models in chemical mass balance analysis of air quality data

    NASA Astrophysics Data System (ADS)

    Christensen, William F.; Gunst, Richard F.

    The chemical mass balance (CMB) equations have been used to apportion observed pollutant concentrations to their various pollution sources. Typical analyses incorporate estimated pollution source profiles, estimated source profile error variances, and error variances associated with the ambient measurement process. Often the CMB model is fit to the data using an iteratively re-weighted least-squares algorithm to obtain the effective variance solution. We consider the chemical mass balance model within the framework of the statistical measurement error model (e.g., Fuller, W.A., Measurement Error Models, Wiley, NewYork, 1987), and we illustrate that the models assumed by each of the approaches to the CMB equations are in fact special cases of a general measurement error model. We compare alternative source contribution estimators with the commonly used effective variance estimator when standard assumptions are valid and when such assumptions are violated. Four approaches for source contribution estimation and inference are compared using computer simulation: weighted least squares (with standard errors adjusted for source profile error), the effective variance approach of Watson et al. (Atmos, Environ., 18, 1984, 1347), the Britt and Luecke (Technometrics, 15, 1973, 233) approach, and a method of moments approach given in Fuller (1987, p. 193). For the scenarios we consider, the simplistic weighted least-squares approach performs as well as the more widely used effective variance solution in most cases, and is slightly superior to the effective variance solution when source profile variability is large. The four estimation approaches are illustrated using real PM 2.5 data from Fresno and the conclusions drawn from the computer simulation are validated.

  3. Selected Ion Flow-Drift Tube Mass Spectrometry: Quantification of Volatile Compounds in Air and Breath.

    PubMed

    Spesyvyi, Anatolii; Smith, David; Španěl, Patrik

    2015-12-15

    A selected ion flow-drift tube mass spectrometric analytical technique, SIFDT-MS, is described that extends the established selected ion flow tube mass spectrometry, SIFT-MS, by the inclusion of a static but variable E-field along the axis of the flow tube reactor in which the analytical ion-molecule chemistry occurs. The ion axial speed is increased in proportion to the reduced field strength E/N (N is the carrier gas number density), and the residence/reaction time, t, which is measured by Hadamard transform multiplexing, is correspondingly reduced. To ensure a proper understanding of the physics and ion chemistry underlying SIFDT-MS, ion diffusive loss to the walls of the flow-drift tube and the mobility of injected H3O(+) ions have been studied as a function of E/N. It is seen that the derived diffusion coefficient and mobility of H3O(+) ions are consistent with those previously reported. The rate coefficient has been determined at elevated E/N for the association reaction of the H3O(+) reagent ions with H2O molecules, which is the first step in the production of H3O(+)(H2O)1,2,3 reagent hydrate ions. The production of hydrated analyte ion was also experimentally investigated. The analytical performance of SIFDT-MS is demonstrated by the quantification of acetone and isoprene in exhaled breath. Finally, the essential features of SIFDT-MS and SIFT-MS are compared, notably pointing out that a much lower speed of the flow-drive pump is required for SIFDT-MS, which facilitates the development of smaller cost-effective analytical instruments for real time breath and fluid headspace analyses. PMID:26583448

  4. A mass balance method for non-intrusive measurements of surface-air trace gas exchange

    NASA Astrophysics Data System (ADS)

    Denmead, O. T.; Harper, L. A.; Freney, J. R.; Griffith, D. W. T.; Leuning, R.; Sharpe, R. R.

    A mass balance method is described for calculating gas production from a surface or volume source in a small test plot from measurements of differences in the horizontal fluxes of the gas across upwind and downwind boundaries. It employs a square plot, 24 m×24 m, with measurements of gas concentration at four heights (up to 3.5 m) along each of the four boundaries. Gas concentrations are multiplied by the appropriate vector winds to yield the horizontal fluxes at each height on each boundary. The difference between these fluxes integrated over downwind and upwind boundaries represents production. Illustrations of the method, which involve exchanges of methane and carbon dioxide, are drawn from experiments with landfills, pastures and grazing animals. Tests included calculation of recovery rates from known gas releases and comparisons with a conventional micrometeorological approach and a backward dispersion model. The method performed satisfactorily in all cases. Its sensitivity for measuring exchanges of CO 2, CH 4 and N 2O in various scenarios was examined. As employed by us, the mass balance method can suffer from errors arising from the large number of gas analyses required for a flux determination, and becomes unreliable when there are light winds and variable wind directions. On the other hand, it is non-disturbing, has a simple theoretical basis, is independent of atmospheric stability or the shape of the wind profile, and is appropriate for flux measurement in situations where conventional micrometeorological methods can not be used, e.g. for small plots, elevated point sources, and heterogeneous surface sources.

  5. Persistent organic contaminants in Saharan dust air masses in West Africa, Cape Verde and the eastern Caribbean

    USGS Publications Warehouse

    Garrison, Virginia H.; Majewski, Michael S.; Foreman, William T.; Genualdi, Susan A.; Mohammed, Azad; Massey Simonich, Stacy L.

    2014-01-01

    Anthropogenic semivolatile organic compounds (SOCs) that persist in the environment, bioaccumulate, are toxic at low concentrations, and undergo long-range atmospheric transport (LRT) were identified and quantified in the atmosphere of a Saharan dust source region (Mali) and during Saharan dust incursions at downwind sites in the eastern Caribbean (U.S. Virgin Islands, Trinidad and Tobago) and Cape Verde. More organochlorine and organophosphate pesticides (OCPPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyl (PCB) congeners were detected in the Saharan dust region than at downwind sites. Seven of the 13 OCPPs detected occurred at all sites: chlordanes, chlorpyrifos, dacthal, dieldrin, endosulfans, hexachlorobenzene (HCB), and trifluralin. Total SOCs ranged from 1.9–126 ng/m3 (mean = 25 ± 34) at source and 0.05–0.71 ng/m3 (mean = 0.24 ± 0.18) at downwind sites during dust conditions. Most SOC concentrations were 1–3 orders of magnitude higher in source than downwind sites. A Saharan source was confirmed for sampled air masses at downwind sites based on dust particle elemental composition and rare earth ratios, atmospheric back trajectory models, and field observations. SOC concentrations were considerably below existing occupational and/or regulatory limits; however, few regulatory limits exist for these persistent organic compounds. Long-term effects of chronic exposure to low concentrations of SOCs are unknown, as are possible additive or synergistic effects of mixtures of SOCs, biologically active trace metals, and mineral dust particles transported together in Saharan dust air masses.

  6. Development of portable mass spectrometer with electron cyclotron resonance ion source for detection of chemical warfare agents in air.

    PubMed

    Urabe, Tatsuya; Takahashi, Kazuya; Kitagawa, Michiko; Sato, Takafumi; Kondo, Tomohide; Enomoto, Shuichi; Kidera, Masanori; Seto, Yasuo

    2014-01-01

    A portable mass spectrometer with an electron cyclotron resonance ion source (miniECRIS-MS) was developed. It was used for in situ monitoring of trace amounts of chemical warfare agents (CWAs) in atmospheric air. Instrumental construction and parameters were optimized to realize a fast response, high sensitivity, and a small body size. Three types of CWAs, i.e., phosgene, mustard gas, and hydrogen cyanide were examined to check if the mass spectrometer was able to detect characteristic elements and atomic groups. From the results, it was found that CWAs were effectively ionized in the miniECRIS-MS, and their specific signals could be discerned over the background signals of air. In phosgene, the signals of the 35Cl+ and 37Cl+ ions were clearly observed with high dose-response relationships in the parts-per-billion level, which could lead to the quantitative on-site analysis of CWAs. A parts-per-million level of mustard gas, which was far lower than its lethal dosage (LCt50), was successfully detected with a high signal-stability of the plasma ion source. It was also found that the chemical forms of CWAs ionized in the plasma, i.e., monoatomic ions, fragment ions, and molecular ions, could be detected, thereby enabling the effective identification of the target CWAs. Despite the disadvantages associated with miniaturization, the overall performance (sensitivity and response time) of the miniECRIS-MS in detecting CWAs exceeded those of sector-type ECRIS-MS, showing its potential for on-site detection in the future. PMID:24211802

  7. Persistent organic contaminants in Saharan dust air masses in West Africa, Cape Verde and the eastern Caribbean.

    PubMed

    Garrison, V H; Majewski, M S; Foreman, W T; Genualdi, S A; Mohammed, A; Massey Simonich, S L

    2014-01-15

    Anthropogenic semivolatile organic compounds (SOCs) that persist in the environment, bioaccumulate, are toxic at low concentrations, and undergo long-range atmospheric transport (LRT) were identified and quantified in the atmosphere of a Saharan dust source region (Mali) and during Saharan dust incursions at downwind sites in the eastern Caribbean (U.S. Virgin Islands, Trinidad and Tobago) and Cape Verde. More organochlorine and organophosphate pesticides (OCPPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyl (PCB) congeners were detected in the Saharan dust region than at downwind sites. Seven of the 13 OCPPs detected occurred at all sites: chlordanes, chlorpyrifos, dacthal, dieldrin, endosulfans, hexachlorobenzene (HCB), and trifluralin. Total SOCs ranged from 1.9-126 ng/m(3) (mean = 25 ± 34) at source and 0.05-0.71 ng/m(3) (mean = 0.24 ± 0.18) at downwind sites during dust conditions. Most SOC concentrations were 1-3 orders of magnitude higher in source than downwind sites. A Saharan source was confirmed for sampled air masses at downwind sites based on dust particle elemental composition and rare earth ratios, atmospheric back trajectory models, and field observations. SOC concentrations were considerably below existing occupational and/or regulatory limits; however, few regulatory limits exist for these persistent organic compounds. Long-term effects of chronic exposure to low concentrations of SOCs are unknown, as are possible additive or synergistic effects of mixtures of SOCs, biologically active trace metals, and mineral dust particles transported together in Saharan dust air masses. PMID:24055669

  8. Spectral effects on latitude-tilt and vertical PV modules as affected by latitude, air mass, and climate

    NASA Astrophysics Data System (ADS)

    Gueymard, Christian A.

    2007-09-01

    Using the same SMARTS radiative code as for the development of improved reference spectra for PV rating, an analysis of the spectral sensitivity of specific PV technologies to varying air mass and other factors is presented. To the difference of previous studies, the approach taken here considers realistic atmospheric conditions, as measured at five North- American sites from widely different climatic zones. Two different PV applications (latitude-tilted flat-plates and vertical building-integrated modules) are showcased with seven possible materials, including a-Si, m-Si, and triple junctions. Considering the most frequent clear-sky conditions around the summer solstice at the selected sites, the Spectral Enhancement Factor (SEF) is calculated both for a fixed air mass (1.5) and daily-average spectral conditions. This analysis provides a preliminary assessment of how latitude, local climatic conditions, and PV geometry affect the relative merits of different technologies relatively to standard rating conditions. In particular, it is shown that, in summer, latitude-tilt PV modules experience bluer incident spectra than the reference spectrum, therefore favoring the a-Si modules (SEF > 1). For vertical-tilt PV systems, the SEF is generally lower than for latitude-tilt systems, with the notable exception of m- Si. When considering daily-average results, the effective SEF can become extremely low in the case of a-Si (down to 0.65) and moderately high for m-Si (up to 1.09). It is concluded that the effects of location, season, and PV material on the spectral effect needs to be investigated in detail, particularly for applications involving vertical building-integrated systems.

  9. Atmospheric pollutants in Chiang Mai (Thailand) over a five-year period (2005-2009), their possible sources and relation to air mass movement

    NASA Astrophysics Data System (ADS)

    Chantara, Somporn; Sillapapiromsuk, Sopittaporn; Wiriya, Wan

    2012-12-01

    Monitoring and analysis of the chemical composition of air pollutants were conducted over a five-year period (2005-2009) in the sub-urban area of Chiang Mai, Thailand. This study aims to determine the seasonal variation of atmospheric ion species and gases, examine their correlations, identify possible sources and assess major air-flow patterns to the receptor. The dominant gas and particulate pollutants were NH3 (43-58%) and SO42- (39-48%), respectively. The annual mean concentrations of NH3 (μg m-3) in descending order were 4.08 (2009) > 3.32 (2007) > 2.68 (2008) > 2.47 (2006) and 1.87 (2005), while those of SO42- (μg m-3) were 2.60 (2007) > 2.20 (2006) > 1.95 (2009) > 1.75 (2008) and 1.26 (2005). Concentrations of particulate ions were analyzed by principle component analysis to find out the possible sources of air pollutants in this area. The first component of each year had a high loading of SO42- and NH4+, which probably came from fuel combustion and agricultural activity, respectively. K+, a tracer of biomass burning, also contributed to the first or the second components of each year. Concentrations of NH4+ and SO42- were well correlated (r > 0.777, p < 0.01), which lead to the conclusion that (NH4)2SO4 was a major compound present in this area. The 3-day backward trajectories of air mass arriving at Chiang Mai from 2005 to 2009 were analyzed using the hybrid single particle langrangian integrated trajectory (HYSPLIT) model and grouped by cluster analysis. The air mass data was analyzed for the dry season (n = 18; 100%). The trajectory of air mass in 2005 mainly originated locally (67%). In 2006, the recorded data showed that 56% of air mass was emitted from the western continental region of Thailand. In 2007, the percent ratios from the western and eastern continental areas were equal (39%). In 2008, 67% originated from the western continental area. In 2009, the recorded air mass mainly came from the western continental area (72%). In conclusion, the

  10. Prospective Multicenter Study of Community-Associated Skin and Skin Structure Infections due to Methicillin-Resistant Staphylococcus aureus in Buenos Aires, Argentina

    PubMed Central

    López Furst, María José; de Vedia, Lautaro; Fernández, Silvina; Gardella, Noella; Ganaha, María Cristina; Prieto, Sergio; Carbone, Edith; Lista, Nicolás; Rotryng, Flavio; Morera, Graciana I.; Mollerach, Marta; Stryjewski, Martín E.

    2013-01-01

    Background Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is now the most common cause of skin and skin structure infections (SSSI) in several world regions. In Argentina prospective, multicenter clinical studies have only been conducted in pediatric populations. Objective Primary: describe the prevalence, clinical and demographic characteristics of adult patients with community acquired SSSI due to MRSA; secondary: molecular evaluation of CA-MRSA strains. Patients with MRSA were compared to those without MRSA. Materials and Methods Prospective, observational, multicenter, epidemiologic study, with molecular analysis, conducted at 19 sites in Argentina (18 in Buenos Aires) between March 2010 and October 2011. Patients were included if they were ≥14 years, were diagnosed with SSSI, a culture was obtained, and there had no significant healthcare contact identified. A logistic regression model was used to identify factors associated with CA-MRSA. Pulse field types, SCCmec, and PVL status were also determined. Results A total of 311 patients were included. CA-MRSA was isolated in 70% (218/311) of patients. Clinical variables independently associated with CA-MRSA were: presence of purulent lesion (OR 3.29; 95%CI 1.67, 6.49) and age <50 years (OR 2.39; 95%CI 1.22, 4.70). The vast majority of CA-MRSA strains causing SSSI carried PVL genes (95%) and were SCCmec type IV. The sequence type CA-MRSA ST30 spa t019 was the predominant clone. Conclusions CA-MRSA is now the most common cause of SSSI in our adult patients without healthcare contact. ST30, SCCmec IV, PVL+, spa t019 is the predominant clone in Buenos Aires, Argentina. PMID:24324543

  11. Combining airborne gas and aerosol measurements with HYSPLIT: a visualization tool for simultaneous evaluation of air mass history and back trajectory consistency

    NASA Astrophysics Data System (ADS)

    Freitag, S.; Clarke, A. D.; Howell, S. G.; Kapustin, V. N.; Campos, T.; Brekhovskikh, V. L.; Zhou, J.

    2014-01-01

    The history of air masses is often investigated using backward trajectories to gain knowledge about processes along the air parcel path as well as possible source regions. Here, we describe a refined approach that incorporates airborne gas, aerosol, and environmental data into back trajectories and show how this technique allows for simultaneous evaluation of air mass history and back trajectory reliability without the need to calculate trajectory errors. We use the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and add a simple semi-automated computing routine to facilitate high-frequency coverage of back trajectories initiated along free tropospheric (FT) flight tracks and profiles every 10 s. We integrate our in situ physiochemical data by color-coding each of these trajectories with its corresponding in situ tracer values measured at the back trajectory start points along the flight path. The unique color for each trajectory aids assessment of trajectory reliability through the visual clustering of air mass pathways of similar coloration. Moreover, marked changes in trajectories associated with marked changes evident in measured physiochemical or thermodynamic properties of an air mass add credence to trajectories. This is particularly true when these air mass properties are linked to trajectory features characteristic of recognized sources or processes. This visual clustering of air mass pathways is of particular value for large-scale 3-D flight tracks common to aircraft experiments where air mass features of interest are often spatially distributed and temporally separated. The cluster-visualization tool used here reveals that most FT back trajectories with pollution signatures measured in the central equatorial Pacific reach back to sources on the South American continent over 10 000 km away and 12 days back in time, e.g., the Amazonian basin. We also demonstrate the distinctions in air mass properties between these and trajectories

  12. An evaluation of the impact of urban air pollution on paint dosimeters by tracking changes in the lipid MALDI-TOF mass spectra profile.

    PubMed

    Herrera, A; Navas, N; Cardell, C

    2016-08-01

    We evaluated the impact of urban air pollution on egg yolk tempera paint dosimeters (binary mixture samples made with historic artist´s blue, red and white pigments) by tracking changes over time in their lipid matrix-assisted laser desorption ionization time-of-flight mass spectra (MALDI-TOF-MS) profiles. We studied triacylglycerols (TGs), phospholipids (PLs) and their oxidation by-products from paint dosimeters that had been exposed outdoors for six months to the polluted atmosphere in the city center of Granada (Spain). Four types of chickens' eggs were also analyzed to find out whether their lipid mass spectra (lipid fingerprints) varied significantly. The ultimate goal of this research is to provide a precise analytical protocol to show whether the changes in the egg yolk identified in paint dosimeters are due to pigment-binder interactions. The Bligh-Dyer (BD) method was optimized for the extraction of the lipids. This innovative procedure included a washing-step prior to the mass spectrometric analysis, which proved crucial for obtaining higher quality lipid fingerprints. A novel interpretation of the results is proposed by applying the BD method, which suggests that transesterification processes occurred in the lipid fractions that were catalyzed by the pigments in the paint dosimeters. In blank dosimeters specific ions produced by oxidative cleavage of PLs and/or TGs may be used as markers of the presence of egg yolk binders. The composition and structure of the specific lipid compounds are also tentatively proposed. In aged dosimeters the intact content of the TGs and PLs decreased; however, we propose that short-chain oxidative products arising from TGs and PLs are present in all the samples, except for the white lead based dosimeter. We end with a new explanation as to why this dosimeter behaves differently from the others. PMID:27216656

  13. PARTICULATE MATTER SAMPLER ERRORS DUE TO THE INTERACTION OF PARTICLE SIZE AND SAMPLER PERFORMANCE CHARACTERISTICS: PM10 AND PM2.5 AMBIENT AIR SAMPLERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural operations across the United States are encountering difficulties in complying with the current air pollution regulations for particulate matter (PM). The National Ambient Air Quality Standards (NAAQS) for PM in terms of PM10, are ambient air concentration limits set by EPA that should ...

  14. Large-Scale Air Mass Characteristics Observed Over the Remote Tropical Pacific Ocean During March-April 1999: Results from PEM-Tropics B Field Experiment

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Fenn, Marta A.; Butler, Carolyn F.; Grant, William B.; Ismail, Syed; Ferrare, Richard A.; Kooi, Susan A.; Brackett, Vincent G.; Clayton, Marian B.; Avery, Melody A.

    2001-01-01

    Eighteen long-range flights over the Pacific Ocean between 38 S to 20 N and 166 E to 90 W were made by the NASA DC-8 aircraft during the NASA Pacific Exploratory Mission (PEM) Tropics B conducted from March 6 to April 18, 1999. Two lidar systems were flown on the DC-8 to remotely measure vertical profiles of ozone (O3), water vapor (H2O), aerosols, and clouds from near the surface to the upper troposphere along their flight track. In situ measurements of a wide range of gases and aerosols were made on the DC-8 for comprehensive characterization of the air and for correlation with the lidar remote measurements. The transition from northeasterly flow of Northern Hemispheric (NH) air on the northern side of the Intertropical Convergence Zone (ITCZ) to generally easterly flow of Southern Hemispheric (SH) air south of the ITCZ was accompanied by a significant decrease in O3, carbon monoxide, hydrocarbons, and aerosols and an increase in H2O. Trajectory analyses indicate that air north of the ITCZ came from Asia and/or the United States, while the air south of the ITCZ had a long residence time over the Pacific, perhaps originating over South America several weeks earlier. Air south of the South Pacific Convergence Zone (SPCZ) came rapidly from the west originating over Australia or Africa. This air had enhanced O3 and aerosols and an associated decrease in H2O. Average latitudinal and longitudinal distributions of O3 and H2O were constructed from the remote and in situ O3 and H2O data, and these distributions are compared with results from PEM-Tropics A conducted in August-October 1996. During PEM-Tropics B, low O3 air was found in the SH across the entire Pacific Basin at low latitudes. This was in strong contrast to the photochemically enhanced O3 levels found across the central and eastern Pacific low latitudes during PEM-Tropics A. Nine air mass types were identified for PEM-Tropics B based on their O3, aerosols, clouds, and potential vorticity characteristics. The

  15. Selective Mass Spectrometer Characterization of Halogen Gases in Air at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Dahl, S.; Ivey, M. M.; Foster, K. L.

    2004-12-01

    We have developed a new interface for use with a commercial ion-trap mass spectrometer equipped with atmospheric pressure chemical ionization (APCI-MS). The new interface uses a mechanical pump to draw gaseous analyte through a glass manifold and into the corona discharge area of the APCI-MS. This new method of delivering a gaseous sample at atmospheric pressure directly to the MS has been used to obtain real-time measurements of Br2 and Cl2 over synthetic seawater ice. The ion intensity of a halogen gas measured by the MS is affected by the pumping rate and the position of the glass manifold. The MS signals for Br2 are linear in the 0.1 to 10.6 ppbv range, and the estimated 3 sigma detection limit is 20.7 pptv. The MS signals for Cl2 are linear in the 0.2 to 25 ppbv range, and the estimated 3 sigma detection limit is 1.081 ppbv. This lab-based technique is suitable to be the basis for a portable field-based design. Such a design, a miniaturized instrument, will help elucidate the role of seawater snow and ice surfaces on the photochemical production of Br2 and Cl2 in the high Arctic.

  16. Long-term measurements of particle number size distributions and the relationships with air mass history and source apportionment in the summer of Beijing

    NASA Astrophysics Data System (ADS)

    Wang, Z. B.; Hu, M.; Wu, Z. J.; Yue, D. L.; He, L. Y.; Huang, X. F.; Liu, X. G.; Wiedensohler, A.

    2013-02-01

    A series of long-term and temporary measurements were conducted to study the improvement of air quality in Beijing during Olympic Games period (8-24 August 2008). To evaluate actions taken to improve the air quality, comparisons of particle number and volume size distributions of August 2008 and 2004-2007 were performed. The total particle number and volume concentrations were 14 000 cm-3 and 37 μm3 cm-3 in August of 2008, respectively. These were reductions of 41% and 35% compared with the mean values of August 2004-2007. A cluster analysis on air mass history and source apportionment were performed, exploring reasons of the reduction of particle concentrations. Back trajectories were classified into five major clusters. Air mass from south direction are always associated with pollution events during the summertime of Beijing. In August 2008, the frequency of air mass arriving from south has been twice higher compared to the average of the previous years, these southerly air masses did however not result in elevated particle volume concentrations in Beijing. This result implied that the air mass history was not the key factor, explaining reduced particle number and volume concentrations during the Beijing 2008 Olympic Games. Four factors were found influencing particle concentrations using a Positive matrix factorization (PMF) model. They were identified to local and remote traffic emissions, combustion sources as well as secondary transformation. The reductions of the four sources were calculated to 47%, 44%, 43% and 30%, respectively. The significant reductions of particle number and volume concentrations may attribute to actions taken, focusing on primary emissions, especially related to the traffic and combustion sources.

  17. Polycyclic aromatic hydrocarbons in air on small spatial and temporal scales - II. Mass size distributions and gas-particle partitioning

    NASA Astrophysics Data System (ADS)

    Lammel, Gerhard; Klánová, Jana; Ilić, Predrag; Kohoutek, Jiří; Gasić, Bojan; Kovacić, Igor; Škrdlíková, Lenka

    2010-12-01

    Polycyclic aromatic hydrocarbons (PAHs) were measured together with inorganic air pollutants at two urban sites and one rural background site in the Banja Luka area, Bosnia and Hercegovina, during 72 h in July 2008 using a high time resolution (5 samples per day) with the aim to study gas-particle partitioning, aerosol mass size distributions and to explore the potential of a higher time resolution (4 h-sampling). In the particulate phase the mass median diameters of the PAHs were found almost exclusively in the accumulation mode (0.1-1.0 μm of size). These were larger for semivolatile PAHs than for non-volatile PAHs. Gas-particle partitioning of semivolatile PAHs was strongly influenced by temperature. The results suggest that the Junge-Pankow model is inadequate to explain the inter-species variation and another process must be significant for phase partitioning which is less temperature sensitive than adsorption. Care should be taken when interpreting slopes m of plots of the type log K p = m log p L0 + b based on 24 h means, as these are found sensitive to the time averaging, i.e. tend to be higher than when based on 12 h-mean samples.

  18. First day of an oil spill on the open sea: early mass transfers of hydrocarbons to air and water.

    PubMed

    Gros, Jonas; Nabi, Deedar; Würz, Birgit; Wick, Lukas Y; Brussaard, Corina P D; Huisman, Johannes; van der Meer, Jan R; Reddy, Christopher M; Arey, J Samuel

    2014-08-19

    During the first hours after release of petroleum at sea, crude oil hydrocarbons partition rapidly into air and water. However, limited information is available about very early evaporation and dissolution processes. We report on the composition of the oil slick during the first day after a permitted, unrestrained 4.3 m(3) oil release conducted on the North Sea. Rapid mass transfers of volatile and soluble hydrocarbons were observed, with >50% of ≤C17 hydrocarbons disappearing within 25 h from this oil slick of <10 km(2) area and <10 μm thickness. For oil sheen, >50% losses of ≤C16 hydrocarbons were observed after 1 h. We developed a mass transfer model to describe the evolution of oil slick chemical composition and water column hydrocarbon concentrations. The model was parametrized based on environmental conditions and hydrocarbon partitioning properties estimated from comprehensive two-dimensional gas chromatography (GC×GC) retention data. The model correctly predicted the observed fractionation of petroleum hydrocarbons in the oil slick resulting from evaporation and dissolution. This is the first report on the broad-spectrum compositional changes in oil during the first day of a spill at the sea surface. Expected outcomes under other environmental conditions are discussed, as well as comparisons to other models. PMID:25103722

  19. Physical and chemical processes of air masses in the Aegean Sea during Etesians: Aegean-GAME airborne campaign.

    PubMed

    Tombrou, M; Bossioli, E; Kalogiros, J; Allan, J D; Bacak, A; Biskos, G; Coe, H; Dandou, A; Kouvarakis, G; Mihalopoulos, N; Percival, C J; Protonotariou, A P; Szabó-Takács, B

    2015-02-15

    High-resolution measurements of gas and aerosols' chemical composition along with meteorological and turbulence parameters were performed over the Aegean Sea (AS) during an Etesian outbreak in the framework of the Aegean-GAME airborne campaign. This study focuses on two distinct Etesian patterns, with similarities inside the Marine Atmospheric Boundary Layer (MABL) and differences at higher levels. Under long-range transport and subsidence the pollution load is enhanced (by 17% for CO, 11% for O3, 28% for sulfate, 62% for organic mass, 47% for elemental carbon), compared to the pattern with a weaker synoptic system. Sea surface temperature (SST) was a critical parameter for the MABL structure, turbulent fluxes and pollutants' distribution at lower levels. The MABL height was below 500 m asl over the eastern AS (favoring higher accumulation), and deeper over the western AS. The most abundant components of total PM1 were sulfate (40-50%) and organics (30-45%). Higher average concentrations measured over the eastern AS (131 ± 76 ppbv for CO, 62.5 ± 4.1 ppbv for O3, 5.0 ± 1.1 μg m(-3) for sulfate, 4.7 ± 0.9 μg m(-3) for organic mass and 0.5 ± 0.2 μg m(-3) for elemental carbon). Under the weaker synoptic system, cleaner but more acidic air masses prevailed over the eastern part, while distinct aerosol layers of different signature were observed over the western part. The Aitken and accumulation modes contributed equally during the long-range transport, while the Aitken modes dominated during local or medium range transport. PMID:25460953

  20. The potential of LIRIC to validate the vertical profiles of the aerosol mass concentration estimated by an air quality model

    NASA Astrophysics Data System (ADS)

    Siomos, Nikolaos; Filoglou, Maria; Poupkou, Anastasia; Liora, Natalia; Dimopoulos, Spyros; Melas, Dimitris; Chaikovsky, Anatoli; Balis, Dimitris

    2015-04-01

    Vertical profiles of the aerosol mass concentration derived by a retrieval algorithm that uses combined sunphotometer and LIDAR data (LIRIC) were used in order to validate the mass concentration profiles estimated by the air quality model CAMx. LIDAR and CIMEL measurements of the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki were used for this validation.The aerosol mass concentration profiles of the fine and coarse mode derived by CAMx were compared with the respective profiles derived by the retrieval algorithm. For the coarse mode particles, forecasts of the Saharan dust transportation model BSC-DREAM8bV2 were also taken into account. Each of the retrieval algorithm's profiles were matched to the models' profile with the best agreement within a time window of four hours before and after the central measurement. OPAC, a software than can provide optical properties of aerosol mixtures, was also employed in order to calculate the angstrom exponent and the lidar ratio values for 355nm and 532nm for each of the model's profiles aiming in a comparison with the angstrom exponent and the lidar ratio values derived by the retrieval algorithm for each measurement. The comparisons between the fine mode aerosol concentration profiles resulted in a good agreement between CAMx and the retrieval algorithm, with the vertical mean bias error never exceeding 7 μgr/m3. Concerning the aerosol coarse mode concentration profiles both CAMx and BSC-DREAM8bV2 values are severely underestimated, although, in cases of Saharan dust transportation events there is an agreement between the profiles of BSC-DREAM8bV2 model and the retrieval algorithm.

  1. Influence of air pressure, humidity, solar radiation, temperature, and wind speed on ambulatory visits due to chronic obstructive pulmonary disease in Bavaria, Germany

    NASA Astrophysics Data System (ADS)

    Ferrari, Uta; Exner, Teresa; Wanka, Eva R.; Bergemann, Christoph; Meyer-Arnek, Julian; Hildenbrand, Beate; Tufman, Amanda; Heumann, Christian; Huber, Rudolf M.; Bittner, Michael; Fischer, Rainald

    2012-01-01

    Chronic obstructive pulmonary disease (COPD) is one of the most important causes of morbidity and mortality in the world. The disease is often aggravated by periods of increased symptoms requiring medical attention. Among the possible triggers for these exacerbations, meteorological factors are under consideration. The objective of this study was to assess the influence of various meteorological factors on the health status of patients with COPD. For this purpose, the daily number of ambulatory care visits due to COPD was analysed in Bavaria, Germany, for the years 2006 and 2007. The meteorological factors were provided by the model at the European Centre for Medium Range Weather Forecast (ECMWF). For the multivariate analysis, a generalised linear model was used. In Bavaria, an increase of 1% of daily consultations (about 103 visits per day) was found to be associated with a change of 0.72 K temperature, 209.55 of log air surface pressure in Pa, and a decrease of 1% of daily consultations with 1,453,763 Ws m2 of solar radiation. There also seem to be regional differences between north and south Bavaria; for instance, the effect of wind speed and specific humidity with a lag of 1 day were only significant in the north. This study could contribute to a tool for the prevention of exacerbations. It also serves as a model for the further evaluation of the impact of meteorological factors on health, and could easily be applied to other diseases or other regions.

  2. Influence of air pressure, humidity, solar radiation, temperature, and wind speed on ambulatory visits due to chronic obstructive pulmonary disease in Bavaria, Germany.

    PubMed

    Ferrari, Uta; Exner, Teresa; Wanka, Eva R; Bergemann, Christoph; Meyer-Arnek, Julian; Hildenbrand, Beate; Tufman, Amanda; Heumann, Christian; Huber, Rudolf M; Bittner, Michael; Fischer, Rainald

    2012-01-01

    Chronic obstructive pulmonary disease (COPD) is one of the most important causes of morbidity and mortality in the world. The disease is often aggravated by periods of increased symptoms requiring medical attention. Among the possible triggers for these exacerbations, meteorological factors are under consideration. The objective of this study was to assess the influence of various meteorological factors on the health status of patients with COPD. For this purpose, the daily number of ambulatory care visits due to COPD was analysed in Bavaria, Germany, for the years 2006 and 2007. The meteorological factors were provided by the model at the European Centre for Medium Range Weather Forecast (ECMWF). For the multivariate analysis, a generalised linear model was used. In Bavaria, an increase of 1% of daily consultations (about 103 visits per day) was found to be associated with a change of 0.72 K temperature, 209.55 of log air surface pressure in Pa, and a decrease of 1% of daily consultations with 1,453,763 Ws m(2) of solar radiation. There also seem to be regional differences between north and south Bavaria; for instance, the effect of wind speed and specific humidity with a lag of 1 day were only significant in the north. This study could contribute to a tool for the prevention of exacerbations. It also serves as a model for the further evaluation of the impact of meteorological factors on health, and could easily be applied to other diseases or other regions. PMID:21301889

  3. Design and Performance of a Triple Source Air Mass Zero Solar Simulator

    NASA Technical Reports Server (NTRS)

    Jenkins, Phillip; Scheiman, David; Snyder, David

    2005-01-01

    Simulating the sun in a laboratory for the purpose of measuring solar cells has long been a challenge for engineers and scientists. Multi-junction cells demand higher fidelity of a solar simulator than do single junction cells, due to a need for close spectral matching as well as AM0 intensity. A GaInP/GaAs/Ge solar cell for example, requires spectral matching in three distinct spectral bands (figure 1). A commercial single source high-pressure xenon arc solar simulator such as the Spectrolab X-25 at NASA Glenn Research Center, can match the top two junctions of a GaInP/GaAs/Ge cell to within 1.3% mismatch, with the GaAs cell receiving slightly more current than required. The Ge bottom cell however, is mismatched +8.8%. Multi source simulators are designed to match the current for all junctions but typically have small illuminated areas, less uniformity and less beam collimation compared to an X-25 simulator. It was our intent when designing a multi source simulator to preserve as many aspects of the X-25 while adding multi-source capability.

  4. Recent trends of persistent organic pollutants in air in central Europe - Air monitoring in combination with air mass trajectory statistics as a tool to study the effectivity of regional chemical policy

    NASA Astrophysics Data System (ADS)

    Dvorská, A.; Lammel, G.; Holoubek, I.

    We use air mass back trajectory analysis of persistent organic pollutant (POP) levels monitored at a regional background site, Košetice, Czech Republic, as a tool to study the effectiveness of emission reduction measures taken in the last decade in the region. The representativity of the chosen trajectory starting height for air sampling near ground was ensured by excluding trajectories starting at time of inversions lower than their starting height. As the relevant pollutant sources are exclusively located in the atmospheric boundary layer, trajectory segments above this layer were also excluded from the analysis. We used a linear time weight to account for the influence of dispersion and deposition on trace components abundances and to quantify the ground source loading, a continuous measure for the influence of surface emissions. Hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs), DDT, and two time periods, the years 1997-1999 and 2004-2006, were studied. The pollutant levels transported to Košetice decreased for all substances except HCB. Except for lindane seasonal emissions were insignificant. Increasing emissions of HCB were at least partly linked to the 2002 floods in the Danube basin. Major emissions of 1997-1999 which decreased significantly were in France (lindane), western Poland, Hungary and northern ex-Yugoslavia (technical HCH), and the Czech Republic (DDT). Emissions remaining in 2004-2006 include HCB and DDT in the northern Czech Republic, HCB and PCBs in Germany. Besides changes in emission strength meteorological factors influence the level of transported pollutant concentrations. The prevailing air flow pattern limits the geographic coverage of this analysis to central Europe and parts of western Europe. However, no POP monitoring stations exist in areas suitable for a possible extension of the study area.

  5. Determining air pollutant emission rates based on mass balance using airborne measurement data over the Alberta oil sands operations

    NASA Astrophysics Data System (ADS)

    Gordon, M.; Li, S.-M.; Staebler, R.; Darlington, A.; Hayden, K.; O'Brien, J.; Wolde, M.

    2015-09-01

    Top-down approaches to measure total integrated emissions provide verification of bottom-up, temporally resolved, inventory-based estimations. Aircraft-based measurements of air pollutants from sources in the Canadian oil sands were made in support of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring during a summer intensive field campaign between 13 August and 7 September 2013. The measurements contribute to knowledge needed in support of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring. This paper describes the top-down emission rate retrieval algorithm (TERRA) to determine facility emissions of pollutants, using SO2 and CH4 as examples, based on the aircraft measurements. In this algorithm, the flight path around a facility at multiple heights is mapped to a two-dimensional vertical screen surrounding the facility. The total transport of SO2 and CH4 through this screen is calculated using aircraft wind measurements, and facility emissions are then calculated based on the divergence theorem with estimations of box-top losses, horizontal and vertical turbulent fluxes, surface deposition, and apparent losses due to air densification and chemical reaction. Example calculations for two separate flights are presented. During an upset condition of SO2 emissions on one day, these calculations are within 5 % of the industry-reported, bottom-up measurements. During a return to normal operating conditions, the SO2 emissions are within 11 % of industry-reported, bottom-up measurements. CH4 emissions calculated with the algorithm are relatively constant within the range of uncertainties. Uncertainty of the emission rates is estimated as less than 30 %, which is primarily due to the unknown SO2 and CH4 mixing ratios near the surface below the lowest flight level.

  6. The Potential of The Synergy of Sunphotometer and Lidar Data to Validate Vertical Profiles of The Aerosol Mass Concentration Estimated by An Air Quality Model

    NASA Astrophysics Data System (ADS)

    Siomos, N.; Filioglou, M.; Poupkou, A.; Liora, N.; Dimopoulos, S.; Melas, D.; Chaikovsky, A.; Balis, D. S.

    2016-06-01

    Vertical profiles of the aerosol mass concentration derived by the Lidar/Radiometer Inversion Code (LIRIC), that uses combined sunphotometer and lidar data, were used in order to validate the aerosol mass concentration profiles estimated by the air quality model CAMx. Lidar and CIMEL measurements performed at the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki, Greece (40.5N, 22.9E) from the period 2013-2014 were used in this study.

  7. Analysis of heat and mass transfer between air and falling film desiccant for different flow configurations in the presence of ultrafine particles

    NASA Astrophysics Data System (ADS)

    Ali, Ahmad A.

    This work focuses on the enhancement of heat and mass transfer between air and falling desiccant film for different flow channel configurations. Cu-Ultrafine particles are added to the desiccant film to investigate the enhancement in heat and mass transfer between air and desiccant film for dehumidification and cooling processes of the air and regeneration of desiccant film. A detailed comparative study between parallel and counter flow channels is performed using a parametric study to investigate the enhancements in dehumidification, cooling, and regeneration processes in terms of the pertinent parameters. The results reveal that the parallel flow arrangement provides better dehumidification and cooling for the air than the counter flow channel for a wide range of parameters. Next, the inclined parallel and counter flow configurations are investigated using an Alternating Direction Implicit (ADI) and successive over-relaxation methods to discretize the vorticity and stream-function equations, respectively. A parametric study is employed to investigate the inclination angle effects in enhancing the heat and mass transfer in terms of the controlling parameters. It is shown that inclination angle plays a significant role in enhancing the dehumidification, cooling, and regeneration processes. Finally, the enhancements in heat and mass transfer in cross flow channel between air and desiccant film is examined based on a parametric study to investigate the dehumidification and cooling processes of the air in terms of the pertinent controlling parameters. These parameters are air and desiccant Reynolds numbers, dimensions of the channel, volume fraction of Cu-ultrafine particles, and thermal dispersion effects. It is found that an increase in the Cu-volume fraction increases dehumidification and cooling capabilities and produce more stable Cu-desiccant film.

  8. Formic and Acetic Acid Observations over Colorado by Chemical Ionization Mass Spectrometry and Organic Acids' Role in Air Quality

    NASA Astrophysics Data System (ADS)

    Treadaway, V.; O'Sullivan, D. W.; Heikes, B.; Silwal, I.; McNeill, A.

    2015-12-01

    Formic acid (HFo) and acetic acid (HAc) have both natural and anthropogenic sources and a role in the atmospheric processing of carbon. These organic acids also have an increasing importance in setting the acidity of rain and snow as precipitation nitrate and sulfate concentrations have decreased. Primary emissions for both organic acids include biomass burning, agriculture, and motor vehicle emissions. Secondary production is also a substantial source for both acids especially from biogenic precursors, secondary organic aerosols (SOAs), and photochemical production from volatile organic compounds (VOCs) and oxygenated volatile organic compounds (OVOCs). Chemical transport models underestimate organic acid concentrations and recent research has sought to develop additional production mechanisms. Here we report HFo and HAc measurements during two campaigns over Colorado using the peroxide chemical ionization mass spectrometer (PCIMS). Iodide clusters of both HFo and HAc were recorded at mass-to-charge ratios of 173 and 187, respectively. The PCIMS was flown aboard the NCAR Gulfstream-V platform during the Deep Convective Clouds and Chemistry Experiment (DC3) and aboard the NCAR C-130 during the Front Range Air Pollution and Photochemistry Experiment (FRAPPE). The DC3 observations were made in May and June 2012 extending from the surface to 13 km over the central and eastern United States. FRAPPE observations were made in July and August 2014 from the surface to 7 km over Colorado. DC3 measurements reported here are focused over the Colorado Front Range and complement the FRAPPE observations. DC3 HFo altitude profiles are characterized by a decrease up to 6 km followed by an increase either back to boundary layer mixing ratio values or higher (a "C" shape). Organic acid measurements from both campaigns are interpreted with an emphasis on emission sources (both natural and anthropogenic) over Colorado and in situ photochemical production especially ozone precursors.

  9. Combining Experiments and Simulation of Gas Absorption for Teaching Mass Transfer Fundamentals: Removing CO2 from Air Using Water and NaOH

    ERIC Educational Resources Information Center

    Clark, William M.; Jackson, Yaminah Z.; Morin, Michael T.; Ferraro, Giacomo P.

    2011-01-01

    Laboratory experiments and computer models for studying the mass transfer process of removing CO2 from air using water or dilute NaOH solution as absorbent are presented. Models tie experiment to theory and give a visual representation of concentration profiles and also illustrate the two-film theory and the relative importance of various…

  10. REAL TIME, ON-LINE CHARACTERIZATION OF DIESEL GENERATOR AIR TOXIC EMISSIONS BY RESONANCE ENHANCED MULTI-PHOTON IONIZATION TIME OF FLIGHT MASS SPECTROMETRY

    EPA Science Inventory

    The laser based resonance, enhanced multi-photon ionization time-of-flight mass spectrometry (REMPI-TOFMS) technique has been applied to the exhaust gas stream of a diesel generator to measure, in real time, concentration levels of aromatic air toxics. Volatile organic compounds ...

  11. Determination of trichloroanisole and trichlorophenol in wineries' ambient air by passive sampling and thermal desorption-gas chromatography coupled to tandem mass spectrometry.

    PubMed

    Camino-Sánchez, F J; Bermúdez-Peinado, R; Zafra-Gómez, A; Ruíz-García, J; Vílchez-Quero, J L

    2015-02-01

    The present paper describes the calibration of selected passive samplers used in the quantitation of trichlorophenol and trichloroanisole in wineries' ambient air, by calculating the corresponding sampling rates. The method is based on passive sampling with sorbent tubes and involves thermal desorption-gas chromatography-triple quadrupole mass spectrometry analysis. Three commercially available sorbents were tested using sampling cartridges with a radial design instead of axial ones. The best results were found for Tenax TA™. Sampling rates (R-values) for the selected sorbents were determined. Passive sampling was also used for accurately determining the amount of compounds present in the air. Adequate correlation coefficients between the mass of the target analytes and exposure time were obtained. The proposed validated method is a useful tool for the early detection of trichloroanisole and its precursor trichlorophenol in wineries' ambient air while avoiding contamination of wine or winery facilities. PMID:25576042

  12. A modelling study of the impact on air quality and health due to the emissions from E85 and petrol fuelled cars in Sweden

    NASA Astrophysics Data System (ADS)

    Fridell, Erik; Haeger-Eugensson, Marie; Moldanova, Jana; Forsberg, Bertil; Sjöberg, Karin

    2014-01-01

    Alternative fuels are becoming more and more important for road traffic and one fuel that has been used for several years is ethanol (E85). The main discussion points regarding the environmental performance for ethanol as a fuel are related to the production. However, there are also some notable differences in the emissions between E85 and petrol fuelled vehicles. This relates to some extent to the emissions of nitrogen oxides (NOx) and particulate matter (PM) but mainly to the composition of the emitted organic compounds. In the present study two fuel scenarios for passenger cars are investigated for the Västra Götaland Region in Sweden; one where the cars with Otto engines run on petrol and one where they run on E85. Two emission scenarios for 2020 are constructed for the whole Europe and coupled dispersion-chemistry modelling is applied to obtain the population exposure to key pollutants. The differences obtained from the modelling show decreased levels of NOx, ozone and benzene with E85 and increased levels of acetaldehyde in the Västra Götaland Region. For the latter the increase may be up to 80%, while NOx and ozone show decreases of up to a few per cent and a few tenths of per cent, respectively. Exposure to the different air pollutants is calculated as population-weighted concentrations. The health risk assessment, using the calculated exposure and published exposure-response functions for the relevant pollutants, shows decreased health risks in the E85 scenario relative the all-petrol scenario, due to the decreased NOx exposure, correlated with both preterm deaths and asthma. However, NOx (and NO2) may partly be indicators of unmeasured causal exhaust components in the epidemiological studies and thus the exposure-response functions for these may not be applicable in the present case where there is a difference in NOx exposure but not a proportional difference in exposure to other exhaust components normally associated with NOx. Smaller effects are

  13. Assimilating airborne gas and aerosol measurements into HYSPLIT: a visualization tool for simultaneous assessment of air mass history and back trajectory reliability

    NASA Astrophysics Data System (ADS)

    Freitag, S.; Clarke, A. D.; Howell, S. G.; Kapustin, V. N.; Campos, T.; Brekhovskikh, V. L.; Zhou, J.

    2013-06-01

    Backward trajectories are commonly used to gain knowledge about the history of airborne observations in terms of possible processes along their path as well as feasible source regions. Here, we describe a refined approach that incorporates airborne gas, aerosol, and environmental data into back trajectories and show how this technique allows for simultaneous assessment of air mass history and back trajectory reliability without the need of calculating trajectory errors. We use the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and add a simple semi-automated computing routine to facilitate high-frequency coverage of back trajectories initiated along the flight track every 10 s. We integrate our in-situ physiochemical data by color-coding each of these trajectories with its corresponding in-situ tracer values measured at the back trajectory start points along the flight path. The unique color for each trajectory aids assessment of trajectory reliability through the visual clustering of air mass pathways of similar coloration. Moreover, marked changes in trajectories associated with marked changes evident in measured physiochemical or thermodynamic properties of an air mass add credence to trajectories, particularly when these air mass properties are linked to trajectory features characteristic of recognized sources or processes. This visual clustering of air mass pathways is of particular value for large-scale 3-D flight tracks common to aircraft experiments where air mass features of interest are often spatially distributed and temporally separated. The cluster-visualization tool used here reveals most back trajectories with pollution signatures measured in the Central Equatorial Pacific reach back to sources on the South American continent over 10 000 km away and 12 days back in time, e.g. the Amazonian basin. We also demonstrate the distinctions in air mass properties between these and trajectories that penetrate deep convection in the

  14. Transport Regimes of Air Masses Affecting the Tropospheric Composition of the Canadian and European Arctic During RACEPAC 2014 and NETCARE 2014/2015

    NASA Astrophysics Data System (ADS)

    Bozem, H.; Hoor, P. M.; Koellner, F.; Kunkel, D.; Schneider, J.; Schulz, C.; Herber, A. B.; Borrmann, S.; Wendisch, M.; Ehrlich, A.; Leaitch, W. R.; Willis, M. D.; Burkart, J.; Thomas, J. L.; Abbatt, J.

    2015-12-01

    The Arctic is warming much faster than any other place in the world and undergoes a rapid change dominated by a changing climate in this region. The impact of polluted air masses traveling to the Arctic from various remote sources significantly contributes to the observed climate change, in contrast there are additional local emission sources contributing to the level of pollutants (trace gases and aerosol). Processes affecting the emission and transport of these pollutants are not well understood and need to be further investigated. We present aircraft based trace gas measurements in the Arctic during RACEPAC (2014) and NETCARE (2014 and 2015) with the Polar 6 aircraft of Alfred Wegener Institute (AWI) covering an area from 134°W to 17°W and 68°N to 83°N. We focus on cloud, aerosol and general transport processes of polluted air masses into the high Arctic. Based on CO and CO2 measurements and kinematic 10-day back trajectories we analyze the transport regimes prevalent during spring (RACEPAC 2014 and NETCARE 2015) and summer (NETCARE 2014) in the observed region. Whereas the eastern part of the Canadian Arctic is affected by air masses with their origin in Asia, in the central and western parts of the Canadian and European Arctic air masses from North America are predominant at the time of the measurement. In general the more northern parts of the Arctic were relatively unaffected by pollution from mid-latitudes since air masses mostly travel within the polar dome, being quite isolated. Associated mixing ratios of CO and CO2 fit into the seasonal cycle observed at NOAA ground stations throughout the Arctic, but show a more mid-latitudinal characteristic at higher altitudes. The transition is remarkably sharp and allows for a chemical definition of the polar dome. At low altitudes, synoptic disturbances transport polluted air masses from mid-latitudes into regions of the polar dome. These air masses contribute to the Arctic pollution background, but also

  15. Gas chromatographic-mass spectroscopic determination of benzene in indoor air during the use of biomass fuels in cooking time.

    PubMed

    Sinha, Sukesh Narayan; Kulkarni, P K; Desai, N M; Shah, S H; Patel, G M; Mansuri, M M; Parikh, D J; Saiyed, H N

    2005-02-18

    A gas chromatography-mass spectroscopic method in electron ionization (EI) mode with MS/MS ion preparation using helium at flow rate 1 ml min(-1) as carrier gas on DB-5 capillary column (30 m x 0.25 mm i.d. film thickness 0.25 microm) has been developed for the determination of benzene in indoor air. The detection limit for benzene was 0.002 microg ml(-1) with S/N: 4 (S: 66, N: 14). The benzene concentration for cooks during cooking time in indoor kitchen using dung fuel was 114.1 microg m(-3) while it was 6.6 microg m(-3) for open type kitchen. The benzene concentration was significantly higher (p < 0.01) in indoor kitchen with respect to open type kitchen using dung fuels. The wood fuel produces 36.5 microg m(-3) of benzene in indoor kitchen. The concentration of benzene in indoor kitchen using wood fuel was significantly (p < 0.01) lower in comparison to dung fuel. This method may be helpful for environmental analytical chemist dealing with GC-MS in confirmation and quantification of benzene in environmental samples with health risk exposure assessment. PMID:15782977

  16. Energetics and efficiency analysis of a cobaloxime-modified semiconductor under simulated air mass 1.5 illumination.

    PubMed

    Krawicz, Alexandra; Cedeno, Diana; Moore, Gary F

    2014-08-14

    We report on the energetics and efficiency of a p-type (100) gallium phosphide (GaP) semiconductor functionalized with molecular hydrogen production catalysts via polymer grafting. The catalysts belong to the cobaloxime class of compounds that have recently shown promise in electrocatalysis and solar-to-fuel applications. Attachment of the complex to a semiconductor surface allows direct photoelectrochemical (PEC) measurements of performance. Under simulated air mass 1.5 illumination, the catalyst-modified photocathode yields a 0.92 mA cm(-2) current density when operating at the equilibrium potential for the hydrogen production half reaction. The open circuit photovoltage (VOC) is 0.72 V vs. a reversible hydrogen electrode (RHE) and the fill factor (FF) is 0.33 (a 258% increase compared to polymer-modified electrodes, without cobaloxime treatment). The external quantum efficiency (EQE), measured under a reverse bias of +0.17 vs. RHE, shows a maximum of 67% under 310 nm illumination. Product analysis of the head-space gas yields a lower limit on the Faradaic efficiency of 88%. In addition, the near linear photoresponse of the current density upon increasing illumination indicates that photocarrier transport to the interface can limit performance. These results give insights into the design of improved photocatalytic constructs with additional performance gains. PMID:24619031

  17. Urban air pollution: a representative survey of PM(2.5) mass concentrations in six Brazilian cities.

    PubMed

    de Miranda, Regina Maura; de Fatima Andrade, Maria; Fornaro, Adalgiza; Astolfo, Rosana; de Andre, Paulo Afonso; Saldiva, Paulo

    2012-03-01

    In urban areas of Brazil, vehicle emissions are the principal source of fine particulate matter (PM(2.5)). The World Health Organization air quality guidelines state that the annual mean concentration of PM(2.5) should be below 10 μg m(-3). In a collaboration of Brazilian institutions, coordinated by the University of São Paulo School of Medicine and conducted from June 2007 to August 2008, PM(2.5) mass was monitored at sites with high traffic volumes in six Brazilian state capitals. We employed gravimetry to determine PM(2.5) mass concentrations, reflectance to quantify black carbon concentrations, X-ray fluorescence to characterize elemental composition, and ion chromatography to determine the composition and concentrations of anions and cations. Mean PM(2.5) concentrations and proportions of black carbon (BC) in the cities of São Paulo, Rio de Janeiro, Belo Horizonte, Curitiba, Recife, and Porto Alegre were 28.1 ± 13.6 μg m(-3) (38% BC), 17.2 ± 11.2 μg m(-3) (20% BC), 14.7 ± 7.7 μg m(-3) (31% BC), 14.4 ± 9.5 μg m(-3) (30% BC), 7.3 ± 3.1 μg m(-3) (26% BC), and 13.4 ± 9.9 μg m(-3) (26% BC), respectively. Sulfur and minerals (Al, Si, Ca, and Fe), derived from fuel combustion and soil resuspension, respectively, were the principal elements of the PM(2.5) mass. We discuss the long-term health effects for each metropolitan region in terms of excess mortality risk, which translates to greater health care expenditures. This information could prove useful to decision makers at local environmental agencies. PMID:22408694

  18. Elemental composition and radical formation potency of PM10 at an urban background station in Germany in relation to origin of air masses

    NASA Astrophysics Data System (ADS)

    Hellack, Bryan; Quass, Ulrich; Beuck, Henning; Wick, Gabriele; Kuttler, Wilhelm; Schins, Roel P. F.; Kuhlbusch, Thomas A. J.

    2015-03-01

    At an urban background station in Mülheim-Styrum, North Rhine Westphalia, Germany, a set of 75 PM10 samples was collected over a one year period, followed by analyses for mass, chemical composition and hydroxyl radical (OHrad) formation potency. Additionally, the origin of air masses for the sampling days was calculated by 48-h backward trajectories, subdivided into the four cardinal sectors. Significant lower PM10 mass concentrations were observed for summertime air masses from the west compared to the other seasons and cardinal sectors. For the OHrad formation potency higher values were detected if air masses originate from east and south, thus predominantly being of continental origin. From the elevated OHrad formation potencies in fall and winter a seasonal trend with low potencies in summers is assumed. Furthermore, source apportionment was performed by a positive matrix factor analysis, separating seven plausible factors which could be attributed to mineral dust, secondary nitrate, industry, non-exhaust traffic, fossil fuel combustion, marine aerosol and secondary aerosol factors. The intrinsic OHrad formation potency was found to be associated mainly with the fossil fuel combustion factor (45%) and industry factor (22%).

  19. Size-Segregated Aerosol Composition and Mass Loading of Atmospheric Particles as Part of the Pacific Northwest 2001(PNW2001) Air Quality Study In Puget Sound

    NASA Astrophysics Data System (ADS)

    Disselkamp, R. S.; Barrie, L. A.; Shutthanadan, S.; Cliff, S.; Cahill, T.

    2001-12-01

    In mid-August, 2001, an aircraft-based air-quality study was performed in the Puget Sound, WA, area entitled PNW2001 (http://www.pnl.gov/pnw2001). The objectives of this field campaign were the following: 1. reveal information about the 3-dimensional distribution of ozone, its gaseous precursors and fine particulate matter during weather conditions favoring air pollution; 2. derive information about the accuracy of urban and biogenic emissions inventories that are used to drive the air quality forecast models; and 3. examine the accuracy of modeled ozone concentration with that observed. In support of these efforts, we collected time-averaged ( { ~}10 minute averages), size-segregated, aerosol composition and mass-loading information using ex post facto analysis techniques of synchrotron x-ray fluorescence (s-XRF), proton induced x-ray emissions(PIXE), proton elastic scattering (PESA), and scanning transmission ion microscopy (STIM). This is the first time these analysis techniques have been used together on samples collected from aircraft using an optimized 3-stage rotating drum impactor. In our presentation, we will discuss the aerosol components in three aerosol size fractions as identified by statistical analysis of multielemental data (including total mass, H, Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Pb) and relate variations in these components to physical aerosol properties, other gaseous trace constituents and to air mass origin.

  20. Development and characterisation of a state-of-the-art GOME-2 formaldehyde air-mass factor algorithm

    NASA Astrophysics Data System (ADS)

    Hewson, W.; Barkley, M. P.; Gonzalez Abad, G.; Bösch, H.; Kurosu, T.; Spurr, R.; Tilstra, L. G.

    2015-10-01

    Space-borne observations of formaldehyde (HCHO) are frequently used to derive surface emissions of isoprene, an important biogenic volatile organic compound. The conversion of retrieved HCHO slant column concentrations from satellite line-of-sight measurements to vertical columns is determined through application of an air mass factor (AMF), accounting for instrument viewing geometry, radiative transfer, and vertical profile of the absorber in the atmosphere. This step in the trace gas retrieval is subject to large errors. This work presents the AMF algorithm in use at the University of Leicester (UoL), which introduces scene-specific variables into a per-observation full radiative transfer AMF calculation, including increasing spatial resolution of key environmental parameter databases, input variable area weighting, instrument-specific scattering weight calculation, and inclusion of an ozone vertical profile climatology. Application of these updates to HCHO slant columns from the GOME-2 instrument is shown to typically adjust the AMF by ±20 %, compared to a reference algorithm without these advanced parameterisations. On average the GOME-2 AMFs increase by 4 %, with over 70 % of locations having an AMF of 0-20 % larger than originally, largely resulting from the use of the latest GOME-2 reflectance product. Furthermore, the new UoL algorithm also incorporates a full radiative transfer error calculation for each scene to help characterise AMF uncertainties. Global median AMF errors are typically 50-60 %, and are driven by uncertainties in the HCHO profile shape and its vertical distribution relative to clouds and aerosols. If uncertainty on the a priori HCHO profile is relatively small (< 10 %) then the median AMF total error decreases to about 30-40 %.

  1. Air Mass Factor Formulation for Spectroscopic Measurements from Satellites: Application to Formaldehyde Retrievals from the Global Ozone Monitoring Experiment

    NASA Technical Reports Server (NTRS)

    Palmer, Paul I.; Jacob, Daniel J.; Chance, Kelly; Martin, Randall V.; Spurr, Robert J. D.; Kurosu, Thomas P.; Bey, Isabelle; Yantosca, Robert; Fiore, Arlene; Li, Qinbin

    2004-01-01

    We present a new formulation for the air mass factor (AMF) to convert slant column measurements of optically thin atmospheric species from space into total vertical columns. Because of atmospheric scattering, the AMF depends on the vertical distribution of the species. We formulate the AMF as the integral of the relative vertical distribution (shape factor) of the species over the depth of the atmosphere, weighted by altitude-dependent coefficients (scattering weights) computed independently from a radiative transfer model. The scattering weights are readily tabulated, and one can then obtain the AMF for any observation scene by using shape factors from a three dimensional (3-D) atmospheric chemistry model for the period of observation. This approach subsequently allows objective evaluation of the 3-D model with the observed vertical columns, since the shape factor and the vertical column in the model represent two independent pieces of information. We demonstrate the AMF method by using slant column measurements of formaldehyde at 346 nm from the Global Ozone Monitoring Experiment satellite instrument over North America during July 1996. Shape factors are cumputed with the Global Earth Observing System CHEMistry (GEOS-CHEM) global 3-D model and are checked for consistency with the few available aircraft measurements. Scattering weights increase by an order of magnitude from the surface to the upper troposphere. The AMFs are typically 20-40% less over continents than over the oceans and are approximately half the values calculated in the absence of scattering. Model-induced errors in the AMF are estimated to be approximately 10%. The GEOS-CHEM model captures 50% and 60% of the variances in the observed slant and vertical columns, respectively. Comparison of the simulated and observed vertical columns allows assessment of model bias.

  2. Measurement and analysis of aerosol and black carbon in the southwestern United States and Panama and their dependence on air mass origin

    NASA Astrophysics Data System (ADS)

    Junker, C.; Sheahan, J. N.; Jennings, S. G.; O'Brien, P.; Hinds, B. D.; Martinez-Twary, E.; Hansen, A. D. A.; White, C.; Garvey, D. M.; Pinnick, R. G.

    2004-07-01

    Total aerosol mass loading, aerosol absorption, and black carbon (BC) content were determined from aerosol collected on 598 quartz fiber filters at a remote, semiarid site near Orogrande, New Mexico from December 1989 to October 1995. Aerosol mass was determined by weighing filters before and after exposure, and aerosol absorption was determined by measuring the visible light transmitted through loaded filter samples and converting these measurements to aerosol absorption. BC content was determined by measuring visible light transmitted through filter samples before and after firing and converting the absorption to BC mass, assuming a BC absorption cross section of 19 m2/g in the fiber filter medium. Two analyses were then performed on each of the logged variables: an autoregressive integrating moving average (ARIMA) analysis and a decomposition analysis using an autoregressive model to accommodate first-order autocorrelation. The two analyses reveal that BC mass has no statistically significant seasonal dependence at the 5% level of significance but only random fluctuations varying around an average annual value that has a long-term decreasing trend (from 0.16 to 0.11 μg/m3 during 1990-1995). Aerosol absorption, which is dominated by BC, also displays random fluctuations about an average value, and decreases from 1.9 Mm-1 to 1.3 Mm-1 during the same period. Unlike BC, aerosol mass at the Orogrande site displays distinctly different character. The analyses reveal a pronounced seasonal dependence, but no long-term trend for aerosol mass. The seasonal indices resulting from the autoregression analysis have a minimum in January (-0.78) and maximum in June (+0.58). The geometric mean value over the 1990-1995 period for aerosol mass is 16.0 μg/m3. Since BC aerosol at the Orogrande site is a product of long-range atmospheric transport, a back trajectory analysis of air masses was conducted. Back trajectory analyses indicate that air masses traversing high population

  3. Effect of repeated targeted mass treatment with praziquantel on the prevalence, intensity of infection and morbidity due to Schistosoma intercalatum in an urban community in equatorial Guinea.

    PubMed

    Simarro, P P; Sima, F O; Mir, M; Ndong, P

    1991-09-01

    A longitudinal community-based study was carried out in order to evaluate the impact of repeated selective population chemotherapy with praziquantel on the epidemiology of an urban focus of Schistosoma intercalatum in the city of Bata, capital of the Continental Region of Equatorial Guinea. Three surveys were undertaken in January of 1988, 1989 and 1990, determining parasitological prevalence, intensity of infection and morbidity and applying repeated targeted mass treatment. One dose of praziquantel (40 mg/kg body weight) was given one week after treatment with mebendazole (100 mg every 12 hours for 3 days). A reduction of the overall prevalence by S. intercalatum of 69.9% and 79.3% in the first and second year respectively was found. Persons showing high parasite burden suffered a reduction of 95.7%. The cure rate (no more eggs in stool) was between 90% and 98.9%. A significant decrease of signs and symptoms was observed. No important side effects were detected. This study shows the positive action of praziquantel in reducing prevalence, intensity of infection and morbidity due to S. intercalatum, above all in the case of a high human population participation response. Cure rates obtained being similar to the ones observed using the same drug in Schistosoma mansoni and Schistosoma haematobium. PMID:1801138

  4. Internalization and cytotoxicity effects of carbon-encapsulated iron nanoparticles in murine endothelial cells: Studies on internal dosages due to loaded mass agglomerates.

    PubMed

    Cywinska, Monika A; Bystrzejewski, Michal; Poplawska, Magdalena; Kosmider, Anita; Zdanowski, Robert; Lewicki, Slawomir; Fijalek, Zbigniew; Ostrowska, Agnieszka; Bamburowicz, Magdalena; Cieszanowski, Andrzej; Grudzinski, Ireneusz P

    2016-08-01

    Carbon-encapsulated iron nanoparticles (CEINs) qualified as metal-inorganic hybrid nanomaterials offer a potential scope for an increasing number of biomedical applications. In this study, we have focused on the investigation of cellular fate and resulting cytotoxic effects of CEINs synthesized using a carbon arc route and studied in murine endothelial (HECa-10) cells. The CEIN samples were characterized as pristine (the mean diameter between 47 and 56nm) and hydrodynamic (the mean diameter between 270 and 460nm) forms and tested using a battery of methods to determine the cell internalization extent and cytotoxicity effects upon to the exposures (0.0001-100μg/ml) in HECa-10 cells. Our studies evidenced that the incubation with CEINs for 24h is accompanied with substantial changes of Zeta potential in cells which can be considered as a key factor for affecting the membrane transport, cellular distribution and cytotoxicity of these nanoparticles. The results demonstrate that CEINs have entered the endothelial cell through the endocytic pathway rather than by passive diffusion and they were mainly loaded as agglomerates on the cell membrane and throughout the cytoplasm, mitochondria and nucleus. The studies show that CEINs induce the mitochondrial and cell membrane cytotoxicities in a dose-dependent manner resulting from the internal dosages due to CEIN agglomerates. Our results highlight the importance of the physicochemical characterization of CEINs in studying the magnetic nanoparticle-endothelial cell interactions because the CEIN mass agglomerates can sediment more or less rapidly in culture models. PMID:27107485

  5. Modeling Effects of Plasma Drag on Low Earth Orbiting Satellites due to Upper Atmospheric Heating by Coronal Mass Ejections and other Solar Events

    NASA Astrophysics Data System (ADS)

    Nwankwo, Victor U. J.; Chakrabarti, Sandip Kumar

    Influence of solar storms and Earth-directed solar energy induced by coronal mass ejections and other solar events on Earth’s upper atmosphere and satellite’s orbit has been studied. It is known that energetic ultraviolet, X-ray and particles emitted from the sun during solar events collectively heat up and subsequently expand the upper atmosphere. This increases drag on LEO satellites. The extent of impact, however, depends on the phase of the solar 11-year cycle. In this study, we first perform a statistical analysis of the time distribution of space environmental parameters such as F10.7 and Ap indices and events due to solar activity during the past cycle. We compute plasma drag on a model artificial satellite during events and predict, using solar cycle forecast, how the satellite orbit would be affected around the peak of current emerging maximum. We find that depending on orbital and design parameters, a typical satellite orbital radius could experience a mean decay of up to 27.44±5.10km per year (with as much as 5.5km contribution from major solar events) during the emerging solar maximum. We also applied the model on a few isolated cases of reported major solar events. The results of the model compared well with reported results of some exiting LEO satellites.

  6. Characteristics of particle number and mass emissions during heavy-duty diesel truck parked active DPF regeneration in an ambient air dilution tunnel

    NASA Astrophysics Data System (ADS)

    Yoon, Seungju; Quiros, David C.; Dwyer, Harry A.; Collins, John F.; Burnitzki, Mark; Chernich, Donald; Herner, Jorn D.

    2015-12-01

    Diesel particle number and mass emissions were measured during parked active regeneration of diesel particulate filters (DPF) in two heavy-duty diesel trucks: one equipped with a DPF and one equipped with a DPF + SCR (selective catalytic reduction), and compliant with the 2007 and 2010 emission standards, respectively. The emission measurements were conducted using an ambient air dilution tunnel. During parked active regeneration, particulate matter (PM) mass emissions measured from a 2007 technology truck were significantly higher than the emissions from a 2010 technology truck. Particle number emissions from both trucks were dominated by nucleation mode particles having a diameter less than 50 nm; nucleation mode particles were orders of magnitude higher than accumulation mode particles having a diameter greater than 50 nm. Accumulation mode particles contributed 77.8 %-95.8 % of the 2007 truck PM mass, but only 7.3 %-28.2 % of the 2010 truck PM mass.

  7. Properties of air mass mixing and humidity in the subtropics from measurements of the D/H isotope ratio of water vapor at the Mauna Loa Observatory

    NASA Astrophysics Data System (ADS)

    Noone, David; Galewsky, Joseph; Sharp, Zachary D.; Worden, John; Barnes, John; Baer, Doug; Bailey, Adriana; Brown, Derek P.; Christensen, Lance; Crosson, Eric; Dong, Feng; Hurley, John V.; Johnson, Leah R.; Strong, Mel; Toohey, Darin; van Pelt, Aaron; Wright, Jonathon S.

    2011-11-01

    Water vapor in the subtropical troposphere plays an important role in the radiative balance, the distribution of precipitation, and the chemistry of the Earth's atmosphere. Measurements of the water vapor mixing ratio paired with stable isotope ratios provide unique information on transport processes and moisture sources that is not available with mixing ratio data alone. Measurements of the D/H isotope ratio of water vapor from Mauna Loa Observatory over 4 weeks in October-November 2008 were used to identify components of the regional hydrological cycle. A mixing model exploits the isotope information to identify water fluxes from time series data. Mixing is associated with exchange between marine boundary layer air and tropospheric air on diurnal time scales and between different tropospheric air masses with characteristics that evolve on the synoptic time scale. Diurnal variations are associated with upslope flow and the transition from nighttime air above the marine trade inversion to marine boundary layer air during daytime. During easterly trade wind conditions, growth and decay of the boundary layer are largely conservative in a regional context but contribute ˜12% of the nighttime water vapor at Mauna Loa. Tropospheric moisture is associated with convective outflow and exchange with drier air originating from higher latitude or higher altitude. During the passage of a moist filament, boundary layer exchange is enhanced. Isotopic data reflect the combination of processes that control the water balance, which highlights the utility for baseline measurements of water vapor isotopologues in monitoring the response of the hydrological cycle to climate change.

  8. sup 222 Rn, sup 222 Rn progeny and sup 220 Rn progeny as atmospheric tracers of air masses at the Mauno Loa Observatory

    SciTech Connect

    Hutter, A.R.; George, A.C.; Maiello, M.L.; Fisenne, I.M.; Larsen, R.J.; Beck, H.L.; Wilson, F.C.

    1990-03-01

    {sup 222}Rn, {sup 222}Rn progeny and {sup 220}Rn progeny concentrations in air were measured at the Mauna Loa Observatory (MLO) in Hawaii during March 1989 in order to investigate the feasibility of using them as atmospheric tracers to help determine local air mass flow patterns. Charcoal traps, cooled to dry ice temperatures, were used to collect {sup 222}Rn, which was subsequently measured in pulse ionization chambers at the Environmental Measurements Laboratory (EML). {sup 222}Rn progeny and {sup 220}Rn progeny for 37 samples were measured at the Observatory by sampling high volumes of air through filters, which were counted for up to 11 h in alpha scintillation counters. Individual progeny concentrations were calculated using both least squares and maximum likelihood techniques. In general, {sup 222}Rn progeny and {sup 220}Rn progeny concentrations were low when free tropospheric air was present (downslope and tradewind conditions), and consistently higher when surface air from the island broke through the trade wind inversion layer (upslope conditions). The data suggest that {sup 222}Rn, {sup 222}Rn progeny, or {sup 220}Rn progeny monitoring may provide new and useful information to help indicate the different air flow patterns present at MLO. 17 refs., 5 figs., 2 tabs.

  9. Temperature Independent Differential Absorption Spectroscopy (tidas) and Simplified Atmospheric Air Mass Factor (samf) Techniques For The Measurement of Ozone Vertical Content From Gome Data

    NASA Astrophysics Data System (ADS)

    Zehner, C.; Casadio, S.; di Sarra, A.; Putz, E.

    A simple technique for the fast retrieval of ozone vertical amount from GOME (Global Ozone Monitoring Experiment) spectra is described in detail. The TIDAS (Tempera- ture Independent Differential Absorption Spectroscopy) technique uses GOME's ca- pability of measuring atmospheric spectra over a broad wavelength range with high spectral resolution. The ozone slant columns are retrieved by applying the Beer- Lambert law to two spectral windows where the ozone absorption cross sections show similar temperature dependence. A simple geometric air mass factor is computed for a fixed height spherical atmosphere (SAMF: Simplified Atmospheric air Mass Factor) to retrieve ozone vertical amounts. Vertical ozone values are compared to the GDP (GOME Data Processor), and to ground based ozone measurements.

  10. Long-term measurements of particle number size distributions and the relationships with air mass history and source apportionment in the summer of Beijing

    NASA Astrophysics Data System (ADS)

    Wang, Z. B.; Hu, M.; Wu, Z. J.; Yue, D. L.; He, L. Y.; Huang, X. F.; Liu, X. G.; Wiedensohler, A.

    2013-10-01

    A series of long-term and temporary measurements were conducted to study the improvement of air quality in Beijing during the Olympic Games period (8-24 August 2008). To evaluate actions taken to improve the air quality, comparisons of particle number and volume size distributions of August 2008 and 2004-2007 were performed. The total particle number and volume concentrations were 14 000 cm-3 and 37 μm-3 cm-3 in August of 2008, respectively. These were reductions of 41% and 35% compared with mean values of August 2004-2007. A cluster analysis on air mass history and source apportionment were performed, exploring reasons for the reduction of particle concentrations. Back trajectories were classified into five major clusters. Air masses from the south direction are always associated with pollution events during the summertime in Beijing. In August 2008, the frequency of air mass arriving from the south was 1.3 times higher compared to the average of the previous years, which however did not result in elevated particle volume concentrations in Beijing. Therefore, the reduced particle number and volume concentrations during the 2008 Beijing Olympic Games cannot be only explained by meteorological conditions. Four factors were found influencing particle concentrations using a positive matrix factorization (PMF) model. They were identified as local and remote traffic emissions, combustion sources as well as secondary transformation. The reductions of the four sources were calculated to 47%, 44%, 43% and 30%, respectively. The significant reductions of particle number and volume concentrations may attribute to actions taken, focusing on primary emissions, especially related to the traffic and combustion sources.

  11. The relationship between seasonal variations of total-nitrogen and total-phosphorus in rainfall and air mass advection paths in Matsue, Japan

    NASA Astrophysics Data System (ADS)

    Yoshioka, Katsuhiro; Kamiya, Hiroshi; Kano, Yoshihiro; Saki, Yukiko; Yamamuro, Masumi; Ishitobi, Yu

    We collected rainwater samples from every rainfall in Matsue, Japan in order to study variations of nitrogen and phosphorus concentrations over time. The seasonal average concentration by magnitude order of Total Nitrogen (here after T-N) was highest in winter, then in spring, fall, and summer and that of Total Phosphorus (here after T-P) was highest in spring, then in winter, fall, and summer. These seasonal variations were examined in relation to the transportation paths of arrived air masses by using a backward trajectory and rainfall patterns from a surface synoptic weather chart. In winter, continental air masses frequently flow from China or Siberia and the resultant winter rainfall is on many occasions of a continental type. In summer, maritime air masses frequently arrive from the Pacific Ocean and this resultant rainfall therefore was often of maritime type. Looking at average concentrations of T-N and T-P for each rainfall type, continental types were high range and maritime types were low. It was therefore concluded that the monthly average concentration of T-N was affected by continental air masses from northern China in winter and by maritime ones from the Pacific Ocean in summer. The maximum deposition of T-N was caused by this concentration in winter and rainfall depth in summer. Seasonal variation of T-P showed a different fluctuation tendency from T-N, with a maximum concentration in spring, and minimum in summer and fall. T-P was susceptible to the yellow sand phenomenon which maximised T-P deposition in spring.

  12. Development of a particle-trap preconcentration-soft ionization mass spectrometric technique for the quantification of mercury halides in air.

    PubMed

    Deeds, Daniel A; Ghoshdastidar, Avik; Raofie, Farhad; Guérette, Élise-Andrée; Tessier, Alain; Ariya, Parisa A

    2015-01-01

    Measurement of oxidized mercury, Hg(II), in the atmosphere poses a significant analytical challenge as Hg(II) is present at ultra-trace concentrations (picograms per cubic meter air). Current technologies are sufficiently sensitive to measure the total Hg present as Hg(II) but cannot determine the chemical speciation of Hg(II). We detail here the development of a soft ionization mass spectrometric technique coupled with preconcentration onto nano- or microparticle-based traps prior to analysis for the measurement of mercury halides in air. The current methodology has comparable detection limits (4-11 pg m(-3)) to previously developed techniques for the measurement of total inorganic mercury in air while allowing for the identification of HgX2 in collected samples. Both mercury chloride and mercury bromide have been sporadically detected in Montreal urban and indoor air using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). We discuss limitations and advantages of the current technique and discuss potential avenues for future research including quantitative trace measurements of a larger range of mercury compounds. PMID:25837315

  13. Who should take responsibility for decisions on internationally recommended datasets? The case of the mass concentration of mercury in air at saturation

    NASA Astrophysics Data System (ADS)

    Brown, Richard J. C.; Brewer, Paul J.; Ent, Hugo; Fisicaro, Paola; Horvat, Milena; Kim, Ki-Hyun; Quétel, Christophe R.

    2015-10-01

    This paper considers how decisions on internationally recommended datasets are made and implemented and, further, how the ownership of these decisions comes about. Examples are given of conventionally agreed data and values where the responsibility is clear and comes about through official designation or by common usage and practice over long time periods. The example of the dataset describing the mass concentration of mercury in air at saturation is discussed in detail. This is a case where there are now several competing datasets that are in disagreement with each other, some with historical authority and some more recent but, arguably, with more robust metrological traceability to the SI. Further, it is elaborated that there is no body charged with the responsibility to make a decision on an international recommendation for such a dataset. This has led to the situation where several competing datasets are in use simultaneously. Close parallels are drawn with the current debate over changes to the ozone absorption cross section, which has equal importance to the measurement of ozone amount fraction in air and to subsequent compliance with air quality legislation. It is noted that in the case of the ozone cross section there is already a committee appointed to deliberate over any change. We make the proposal that a similar committee, under the auspices of IUPAC or the CIPM’s CCQM (if it adopted a reference data function) could be formed to perform a similar role for the mass concentration of mercury in air at saturation.

  14. PM2.5 chemical composition at a rural background site in Central Europe, including correlation and air mass back trajectory analysis

    NASA Astrophysics Data System (ADS)

    Schwarz, Jaroslav; Cusack, Michael; Karban, Jindřich; Chalupníčková, Eva; Havránek, Vladimír; Smolík, Jiří; Ždímal, Vladimír

    2016-07-01

    of fresh, local aerosol and aged, long-range transport aerosol. The influences of different air masses were also investigated. The lowest concentrations of PM2.5 were recorded under the influence of marine air masses from the NW, which were also marked by increased concentrations of marine aerosol. In contrast, the highest concentrations of PM2.5 and most major chemical components were measured during periods when continental easterly air masses were dominant.

  15. Changes in air quality and tropospheric composition due to depletion of stratospheric ozone and interactions with changing climate: implications for human and environmental health.

    PubMed

    Madronich, S; Shao, M; Wilson, S R; Solomon, K R; Longstreth, J D; Tang, X Y

    2015-01-01

    UV radiation is an essential driver for the formation of photochemical smog, which includes ground-level ozone and particulate matter (PM). Recent analyses support earlier work showing that poor outdoor air quality is a major environmental hazard as well as quantifying health effects on regional and global scales more accurately. Greater exposure to these pollutants has been linked to increased risks of cardiovascular and respiratory diseases in humans and is associated globally with several million premature deaths per year. Ozone also has adverse effects on yields of crops, leading to loss of billions of US dollars each year. These detrimental effects also may alter biological diversity and affect the function of natural ecosystems. Future air quality will depend mostly on changes in emission of pollutants and their precursors, but changes in UV radiation and climate will contribute as well. Significant reductions in emissions, mainly from the energy and transportation sectors, have already led to improved air quality in many locations. Air quality will continue to improve in those cities/states that can afford controls, and worsen where the regulatory infrastructure is not available. Future changes in UV radiation and climate will alter the rates of formation of ground-level ozone and photochemically-generated particulate matter and must be considered in predictions of air quality. The decrease in UV radiation associated with recovery of stratospheric ozone will, according to recent global atmospheric model simulations, lead to increases in ground-level ozone at most locations. If correct, this will add significantly to future ground-level ozone trends. However, the spatial resolution of these global models is insufficient to inform policy at this time, especially for urban areas. UV radiation affects the atmospheric concentration of hydroxyl radicals, ˙OH, which are responsible for the self-cleaning of the atmosphere. Recent measurements confirm that, on a

  16. Intercomparison of OMI NO2 and HCHO air mass factor calculations: recommendations and best practices for retrievals

    NASA Astrophysics Data System (ADS)

    Lorente Delgado, Alba; Klaas Boersma, Folkert; Hilboll, Andreas; Richter, Andreas; Yu, Huan; van Roozendael, Michel; Dörner, Steffen; Wagner, Thomas; Barkley, Michael; Lamsal, Lok; Lin, Jintai; Liu, Mengyao

    2016-04-01

    We present a detailed comparison of the air mass factor (AMF) calculation process used by various research groups for OMI satellite retrievals of NO2 and HCHO. Although satellite retrievals have strongly improved over the last decades, there is still a need to better understand and reduce the uncertainties associated with every retrieval step of satellite data products, such as the AMF calculation. Here we compare and evaluate the different approaches used to calculate AMFs by several scientific groups (KNMI (WUR), IASB-BIRA, IUP-UNI. BREMEN, MPI-C, NASA GSFC, LEICESTER UNI. and PEKING UNI.). Each group calculated altitude dependent (box-) AMFs and clear sky and total tropospheric AMFs for several OMI orbits. First, European groups computed AMFs for one OMI orbit using common settings for the choice of surface albedo data, terrain height, cloud treatment and a priori vertical profile. Second, every group computed AMFs for two complete days in different seasons using preferred settings for the ancillary data and cloud treatment as a part of a Round Robin exercise. Box-AMFs comparison showed good consistency and underlined the importance of a correct treatment of the physical processes affecting the effective light path and the vertical discretization of the atmosphere. Using common settings, tropospheric NO2 AMFs in polluted pixels on average agreed within 4.7% whereas in remote pixels agreed within 3.5%. Using preferred settings relative differences between AMFs increase up to 15-30%. This increase is traced back to the different choices and assumptions made throughout the AMF calculation, which affect the final AMF values and thus the uncertainty in the AMF calculation. Differences between state of the art cloud treatment approaches highlight the importance of an accurate cloud correction: total and clear sky AMFs in polluted conditions differ by up to 40% depending on the retrieval scenario. Based on the comparison results, specific recommendations on best

  17. Tillandsia usneoides: a successful alternative for biomonitoring changes in air quality due to a new highway in São Paulo, Brazil.

    PubMed

    Cardoso-Gustavson, Poliana; Fernandes, Francine Faia; Alves, Edenise Segala; Victorio, Mariana Pereira; Moura, Barbara Baesso; Domingos, Marisa; Rodrigues, Caroline Albuquerque; Ribeiro, Andreza Portella; Nievola, Catarina Carvalho; Figueiredo, Ana Maria G

    2016-01-01

    Tillandsia usneoides is an aerial epiphytic bromeliad that absorbs water and nutrients directly from the atmosphere by scales covering its surface. We expanded the use of this species as a broader biomonitor based on chemical and structural markers to detect changes in air quality. The usefulness of such comprehensive approach was tested during the construction and opening of a highway (SP-21) in São Paulo State, Brazil. The biomonitoring study was performed from 2009 to 2012, thus comprising the period during construction and after the highway inauguration. Metal accumulation and structural alterations were assessed, in addition to microscopy analyses to understand the metal chelation in plant tissues and to assess the causes of alterations in the number and shape of scale cells. Altogether, our analyses support the use of this species as a wide biomonitor of air quality in urbanized areas. PMID:26396016

  18. Impact of air quality in Mexico City due to particles smaller than ten microns (PM10) by wildland fire in "Cumbres del Ajusco Park" for the year 2013

    NASA Astrophysics Data System (ADS)

    Mendoza, A.; Garcia-Reynoso, J. A.; Ruiz-Suárez, L. G.; Torres, R.; Castro, T.; Peralta, O.; Padilla Barrera, Z. V.; Mar, B.; Carbajal, J. N.

    2014-12-01

    A forest fire is a natural process of combustion in a specific geographical area, its occurrence depends on meteorological variables, topography and vegetation type, the wildland fires are potential sources of large amounts of pollutants. The main air pollutants are in a wildland fires particles (PM10 and PM2.5) Carbon Monoxide (CO), nitrogen oxides (NOx), volatile organic compounds (VOC's) and a negligible amount of sulfur dioxide (SO2) (Chow 1995), Was performed a study of the environmental impact on air quality in Mexico city for a wildland fire. The fire was presented in Cumbres del Ajusco Park on April 14 for the year 2013, with a duration of 26 hours and consuming an extension 150 ha of pasture, WRF-Chem and WRF-fire model were used to conduct the study, two modeling scenarios were made, one including emissions from wildfire and other without emission-fire, comparison is made between the two modeling scenarios in order to calculate on air quality in Mexico cityPM10 concentrations have a larger impact on the air quality of Mexico city, when fire emission were included, a plume of PM10 coming from fire increase ambient concentration up to 350ug/m3 and it was obtained by modeling similar to the concentration measured by a monitoring station (320ug/m3).The current limit is 120ug/m3 24 hours average. (Mexican standard NOM-025-SSA1-1993)This system for setting emissions from fire is working properly whoever further development is required.

  19. An abrupt reduction in end-tidal carbon-dioxide during neurosurgery is not always due to venous air embolism: a capnograph artefact.

    PubMed

    Vinay, Byrappa; Sriganesh, Kamath; Gopala Krishna, Kadarapura Nanjundaiah

    2014-04-01

    Venous air embolism (VAE) is a well recognized complication during neurosurgery. Pre-cordial doppler and trans-esophageal echocardiography are sensitive monitors for the detection of VAE. A sudden, abrupt reduction in the end-tidal carbondioxide (ETCO2) pressure with associated hypotension during neurosurgery might suggest VAE, when more sensitive monitors are not available. We describe an unusual cause for sudden reduction in ETCO2 during neurosurgery and discuss the mechanism for such presentation. PMID:23996497

  20. A shift in emission time profiles of fossil fuel combustion due to energy transitions impacts source receptor matrices for air quality.

    PubMed

    Hendriks, Carlijn; Kuenen, Jeroen; Kranenburg, Richard; Scholz, Yvonne; Schaap, Martijn

    2015-03-01

    Effective air pollution and short-lived climate forcer mitigation strategies can only be designed when the effect of emission reductions on pollutant concentrations and health and ecosystem impacts are quantified. Within integrated assessment modeling source-receptor relationships (SRRs) based on chemistry transport modeling are used to this end. Currently, these SRRs are made using invariant emission time profiles. The LOTOS-EUROS model equipped with a source attribution module was used to test this assumption for renewable energy scenarios. Renewable energy availability and thereby fossil fuel back up are strongly dependent on meteorological conditions. We have used the spatially and temporally explicit energy model REMix to derive time profiles for backup power generation. These time profiles were used in LOTOS-EUROS to investigate the effect of emission timing on air pollutant concentrations and SRRs. It is found that the effectiveness of emission reduction in the power sector is significantly lower when accounting for the shift in the way emissions are divided over the year and the correlation of emissions with synoptic situations. The source receptor relationships also changed significantly. This effect was found for both primary and secondary pollutants. Our results indicate that emission timing deserves explicit attention when assessing the impacts of system changes on air quality and climate forcing from short lived substances. PMID:25594282

  1. Effects of Thermal Mass, Window Size, and Night-Time Ventilation on Peak Indoor Air Temperature in the Warm-Humid Climate of Ghana

    PubMed Central

    Amos-Abanyie, S.; Akuffo, F. O.; Kutin-Sanwu, V.

    2013-01-01

    Most office buildings in the warm-humid sub-Saharan countries experience high cooling load because of the predominant use of sandcrete blocks which are of low thermal mass in construction and extensive use of glazing. Relatively, low night-time temperatures are not harnessed in cooling buildings because office openings remain closed after work hours. An optimization was performed through a sensitivity analysis-based simulation, using the Energy Plus (E+) simulation software to assess the effects of thermal mass, window size, and night ventilation on peak indoor air temperature (PIAT). An experimental system was designed based on the features of the most promising simulation model, constructed and monitored, and the experimental data used to validate the simulation model. The results show that an optimization of thermal mass and window size coupled with activation of night-time ventilation provides a synergistic effect to obtain reduced peak indoor air temperature. An expression that predicts, indoor maximum temperature has been derived for models of various thermal masses. PMID:23878528

  2. The effect of long-range air mass transport pathways on PM10 and NO2 concentrations at urban and rural background sites in Ireland: Quantification using clustering techniques.

    PubMed

    Donnelly, Aoife A; Broderick, Brian M; Misstear, Bruce D

    2015-01-01

    The specific aims of this paper are to: (i) quantify the effects of various long range transport pathways nitrogen dioxide (NO2) and particulate matter with diameter less than 10μm (PM10) concentrations in Ireland and identify air mass movement corridors which may lead to incidences poor air quality for application in forecasting; (ii) compare the effects of such pathways at various sites; (iii) assess pathways associated with a period of decreased air quality in Ireland. The origin of and the regions traversed by an air mass 96h prior to reaching a receptor is modelled and k-means clustering is applied to create air-mass groups. Significant differences in air pollution levels were found between air mass cluster types at urban and rural sites. It was found that easterly or recirculated air masses lead to higher NO2 and PM10 levels with average NO2 levels varying between 124% and 239% of the seasonal mean and average PM10 levels varying between 103% and 199% of the seasonal mean at urban and rural sites. Easterly air masses are more frequent during winter months leading to higher overall concentrations. The span in relative concentrations between air mass clusters is highest at the rural site indicating that regional factors are controlling concentration levels. The methods used in this paper could be applied to assist in modelling and forecasting air quality based on long range transport pathways and forecast meteorology without the requirement for detailed emissions data over a large regional domain or the use of computationally demanding modelling techniques. PMID:25901845

  3. Operational Use of the AIRS Total Column Ozone Retrievals Along with the RGB Air Mass Product as Part of the GOES-R Proving Ground

    NASA Technical Reports Server (NTRS)

    Folmer, Michael; Zavodsky, Bradley; Molthan, Andrew

    2012-01-01

    The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Prediction (NCEP) Hydrometeorological Prediction Center (HPC) and Ocean Prediction Center (OPC) provide short-term and medium-range forecast guidance of heavy precipitation, strong winds, and other features often associated with mid-latitude cyclones over both land and ocean. As a result, detection of factors that lead to rapid cyclogenesis and high wind events is key to improving forecast skill. One phenomenon that has been identified with these events is the stratospheric intrusion that occurs near tropopause folds. This allows for deep mixing near the top of the atmosphere where dry air high in ozone concentrations and potential vorticity descends (sometimes rapidly) deep into the mid-troposphere. Observations from satellites can aid in detection of these stratospheric air intrusions (SAI) regions. Specifically, multispectral composite imagery assign a variety of satellite spectral bands to the red, green, and blue (RGB) color components of imagery pixels and result in color combinations that can assist in the detection of dry stratospheric air associated with PV advection, which in turn may alert forecasters to the possibility of a rapidly strengthening storm system. Single channel or RGB satellite imagery lacks quantitative information about atmospheric moisture unless the sampled brightness temperatures or other data are converted to estimates of moisture via a retrieval process. Thus, complementary satellite observations are needed to capture a complete picture of a developing storm system. Here, total column ozone retrievals derived from a hyperspectral sounder are used to confirm the extent and magnitude of SAIs. Total ozone is a good proxy for defining locations and intensity of SAIs and has been used in studies evaluating that phenomenon (e.g. Tian et al. 2007, Knox and Schmidt 2005). Steep gradients in values of total ozone seen by satellites have been linked

  4. Model for roughening and ripple instability due to ion-induced mass redistribution [Addendum to H. Hofsäss, Appl. Phys. A 114 (2014) 401, "Surface instability and pattern formation by ion-induced erosion and mass redistribution"

    NASA Astrophysics Data System (ADS)

    Hofsäss, Hans

    2015-05-01

    Carter and Vishnyakov introduced a model (CV model) to describe roughening and ripple instability due to ion-induced mass redistribution. This model is based on the assumption that the irradiated surface layer on a static solid substrate is described by a viscous incompressible thin film bound to the substrate by a "no slip" and "no transport" kinematic boundary condition, i.e. similar to a thin film of viscous paint. However, this boundary condition is incomplete for a layer under ion irradiation. The boundary condition must allow exchange of atoms between the substrate and the irradiated film, so that the thickness of the film is always determined by the size of the collision cascade, independent of the evolution of the surface height profile. In addition, the film thickness depends on the local ion incidence angle, which leads to a time dependence of the film thickness at a given position. The equation of motion of the surface and interface profiles for these boundary conditions is introduced, and a new curvature-dependent coefficient is found which is absent in the CV model. This curvature coefficient depends on the angular derivative of the layer thickness and the atomic drift velocity at the film surface induced by recoil events. Such a stabilizing curvature coefficient was introduced in Appl. Phys. A 114 (2014) 401 and is most pronounced at intermediate angles.

  5. Health effects of air pollution due to coal combustion in the Chestnut Ridge region of Pennsylvania: cross-section survey of children

    SciTech Connect

    Schenker, M.B.; Vedal, S.; Batterman, S.; Samet, J.; Speizer, F.E.

    1986-03-01

    A cross-sectional study of 4071 children aged 6-11 yr of age from a rural region of Western Pennsylvania was conducted in spring of 1979. Standardized children's questionnaires were distributed to the parents and returned by the children to school, where spirometry was performed. The region was divided into low-, moderate-, and high-pollution areas on the basis of the 1974-1978, 3-hr, 24-hr, and annual averages for sulfur dioxide (SO/sub 2/). Seventeen monitoring stations in the region and a triangulation procedure were used to estimate centroid levels in each geographic residence area. After adjusting the respiratory symptom response outcomes and the pulmonary function levels for known predictors, no significant association was noted for level of SO/sub 2/. However, the highest exposure categories were only slightly above the present annual and 24-hr National Air Quality Standards for SO/sub 2/. We conclude that at levels of exposure to which these children were exposed, only by study of potentially sensitive subsets or measures of acute response would it be possible to detect respiratory outcomes associated with ambient air pollution.

  6. Observation of the transport of polluted air masses from the northeastern United States to Cape Sable Island, Nova Scotia, Canada, during the 1993 NARE summer intensive

    NASA Astrophysics Data System (ADS)

    Knapp, K. G.; Balsley, B. B.; Jensen, M. L.; Hanson, H. P.; Birks, J. W.

    1998-06-01

    Vertical profiles of ozone, temperature, pressure, and water vapor mass mixing ratio obtained using a parafoil kite platform during the North Atlantic Regional Experiment (NARE) 1993 summer intensive at Cape Sable Island, Nova Scotia, Canada, demonstrate the of use of kite platforms for the collection of vertically and temporally resolved data over a fixed location. During the period August 8-28, 1993, 39 profiles of the lower atmosphere were collected. Data collected as part of this field campaign illustrate the complex vertical stratification and temporal variability of pollutants transported into the Maritime Provinces of Canada. Transport phenomena resulted in pollution events in which ozone at the ground level remained in the 20-40 parts per billion by volume (ppbv) range, while mixing ratios of 90-130 ppbv were observed above ˜300 m. Back trajectories indicate that these highly elevated levels of ozone are attributable to source regions in the heavily industrialized northeastern United States. Vertical stratification of the lower atmosphere was also present during transport of Canadian air to the sampling site, with layers of both elevated and diminished ozone observed, while marine air did not exhibit layering characteristic of air masses originating from continental source regions.

  7. Development of a thermal desorption gas chromatography-mass spectrometry method for quantitative determination of haloanisoles and halophenols in wineries' ambient air.

    PubMed

    Camino-Sánchez, F J; Ruiz-García, J; Zafra-Gómez, A

    2013-08-30

    An analytical method for the detection and quantification of haloanisoles and their corresponding halophenols in wineries' ambient air was developed. The target analytes were haloanisoles and halophenols, reported by previous scientific literature as responsible for wine taint. A calibrated pump and active tubes filled with Tenax GR™ were used for sampling. These tubes were thermally desorbed and analyzed using gas chromatography-triple quadrupole mass spectrometry in the selected reaction monitoring mode. The adsorption efficiencies of five commercial sampling tubes filled with different materials were evaluated. The efficiencies of the selected adsorbent were close to 100% for all sampled compounds. Desorption, chromatographic and mass spectrometric conditions were accurately optimized allowing very low limits of quantification and wide linear ranges. The limits of quantification in ambient air ranged from 0.8pgtube(-1) for 2,4,6-trichlorophenol, to 28pgtube(-1) for pentachlorophenol. These results are of great importance because human sensory threshold for haloanisoles is very low. The chromatographic method was also validated and the instrumental precision and trueness were established, a maximum RSD of 9% and a mean recovery of 91-106% were obtained. The proposed method involves an easy and sensitive technique for the early detection of haloanisoles and their precursor halophenols in ambient air avoiding contamination of wine or winery facilities. PMID:23891369

  8. The Use of Red Green Blue Air Mass Imagery to Investigate the Role of Stratospheric Air in a Non-convective Wind Event

    NASA Technical Reports Server (NTRS)

    Berndt, E. B.; Zavodsky, B. T.; Jedlovec, G. J.; Molthan, A. L.

    2013-01-01

    Non-convective wind events commonly occur with passing extratropical cyclones and have significant societal and economic impacts. Since non-convective winds often occur in the absence of specific phenomena such as a thunderstorm, tornado, or hurricane, the public are less likely to heed high wind warnings and continue daily activities. Thus non-convective wind events result in as many fatalities as straight line thunderstorm winds. One physical explanation for non-convective winds includes tropopause folds. Improved model representation of stratospheric air and associated non-convective wind events could improve non-convective wind forecasts and associated warnings. In recent years, satellite data assimilation has improved skill in forecasting extratropical cyclones; however errors still remain in forecasting the position and strength of extratropical cyclones as well as the tropopause folding process. The goal of this study is to determine the impact of assimilating satellite temperature and moisture retrieved profiles from hyperspectral infrared (IR) sounders (i.e. Atmospheric Infrared Sounder (AIRS), Cross-track Infrared and Microwave Sounding Suite (CrIMSS), and Infrared Atmospheric Sounding Interferometer (IASI)) on the model representation of the tropopause fold and an associated high wind event that impacted the Northeast United States on 09 February 2013. Model simulations using the Advanced Research Weather Research and Forecasting Model (ARW) were conducted on a 12-km grid with cycled data assimilation mimicking the operational North American Model (NAM). The results from the satellite assimilation run are compared to a control experiment (without hyperspectral IR retrievals), Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis, and Rapid Refresh analyses.

  9. Evaluation of chemical transport model predictions of primary organic aerosol for air masses classified by particle component-based factor analysis

    NASA Astrophysics Data System (ADS)

    Stroud, C. A.; Moran, M. D.; Makar, P. A.; Gong, S.; Gong, W.; Zhang, J.; Slowik, J. G.; Abbatt, J. P. D.; Lu, G.; Brook, J. R.; Mihele, C.; Li, Q.; Sills, D.; Strawbridge, K. B.; McGuire, M. L.; Evans, G. J.

    2012-09-01

    Observations from the 2007 Border Air Quality and Meteorology Study (BAQS-Met 2007) in Southern Ontario, Canada, were used to evaluate predictions of primary organic aerosol (POA) and two other carbonaceous species, black carbon (BC) and carbon monoxide (CO), made for this summertime period by Environment Canada's AURAMS regional chemical transport model. Particle component-based factor analysis was applied to aerosol mass spectrometer measurements made at one urban site (Windsor, ON) and two rural sites (Harrow and Bear Creek, ON) to derive hydrocarbon-like organic aerosol (HOA) factors. A novel diagnostic model evaluation was performed by investigating model POA bias as a function of HOA mass concentration and indicator ratios (e.g. BC/HOA). Eight case studies were selected based on factor analysis and back trajectories to help classify model bias for certain POA source types. By considering model POA bias in relation to co-located BC and CO biases, a plausible story is developed that explains the model biases for all three species. At the rural sites, daytime mean PM1 POA mass concentrations were under-predicted compared to observed HOA concentrations. POA under-predictions were accentuated when the transport arriving at the rural sites was from the Detroit/Windsor urban complex and for short-term periods of biomass burning influence. Interestingly, the daytime CO concentrations were only slightly under-predicted at both rural sites, whereas CO was over-predicted at the urban Windsor site with a normalized mean bias of 134%, while good agreement was observed at Windsor for the comparison of daytime PM1 POA and HOA mean values, 1.1 μg m-3 and 1.2 μg m-3, respectively. Biases in model POA predictions also trended from positive to negative with increasing HOA values. Periods of POA over-prediction were most evident at the urban site on calm nights due to an overly-stable model surface layer. This model behaviour can be explained by a combination of model under

  10. Numerical investigation of interfacial mass transport resistance and two-phase flow in PEM fuel cell air channels

    NASA Astrophysics Data System (ADS)

    Koz, Mustafa

    Proton exchange membrane fuel cells (PEMFCs) are efficient and environmentally friendly electrochemical engines. The performance of a PEMFC is adversely affected by oxygen (O2) concentration loss from the air flow channel to the cathode catalyst layer (CL). Oxygen transport resistance at the gas diffusion layer (GDL) and air channel interface is a non-negligible component of the O2 concentration loss. Simplified PEMFC performance models in the available literature incorporate the O2 resistance at the GDL-channel interface as an input parameter. However, this parameter has been taken as a constant so far in the available literature and does not reflect variable PEMFC operating conditions and the effect of two-phase flow in the channels. This study numerically calculates the O2 transport resistance at the GDL-air channel interface and expresses this resistance through the non-dimensional Sherwood number (Sh). Local Sh is investigated in an air channel with multiple droplets and films inside. These water features are represented as solid obstructions and only air flow is simulated. Local variations of Sh in the flow direction are obtained as a function of superficial air velocity, water feature size, and uniform spacing between water features. These variations are expressed with mathematical expressions for the PEMFC performance models to utilize and save computational resources. The resulting mathematical correlations for Sh can be utilized in PEMFC performance models. These models can predict cell performance more accurately with the help of the results of this work. Moreover, PEMFC performance models do not need to use a look-up table since the results were expressed through correlations. Performance models can be kept simplified although their predictions will become more realistic. Since two-phase flow in channels is experienced mostly at lower temperatures, performance optimization at low temperatures can be done easier.

  11. Improved detection of low vapor pressure compounds in air by serial combination of single-sided membrane introduction with fiber introduction mass spectrometry (SS-MIMS-FIMS).

    PubMed

    Cotte-Rodríguez, Ismael; Handberg, Eric; Noll, Robert J; Kilgour, David P A; Cooks, R Graham

    2005-05-01

    The use of two methods in tandem, single-sided membrane introduction mass spectrometry (SS-MIMS) and fiber introduction mass spectrometry (FIMS), is presented as a technique for field analysis. The combined SS-MIMS-FIMS technique was employed in both a modified commercial mass spectrometer and a miniature mass spectrometer for the selective preconcentration of the explosive simulant o-nitrotoluene (ONT) and the chemical warfare agent simulant, methyl salicylate (MeS), in air. A home-built FIMS inlet was fabricated to allow introduction of the solid-phase microextraction (SPME) fiber into the mass spectrometer chamber and subsequent desorption of the trapped compounds using resistive heating. The SS-MIMS preconcentration system was also home-built from commercial vacuum parts. Optimization experiments were done separately for each preconcentration system to achieve the best extraction conditions prior to use of the two techniques in combination. Improved limits of detection, in the low ppb range, were observed for the combination compared to FIMS alone, using several SS-MIMS preconcentration cycles. The SS-MIMS-FIMS response for both instruments was found to be linear over the range 50 to 800 ppb. Other parameters studied were absorption time profiles, effects of sample flow rate, desorption temperature, fiber background, memory effects, and membrane fatigue. This simple, sensitive, accurate, robust, selective, and rapid sample preconcentration and introduction technique shows promise for field analysis of low vapor pressure compounds, where analyte concentrations will be extremely low and the compounds are difficult to extract from a matrix like air. PMID:15852137

  12. Sensitive and comprehensive detection of chemical warfare agents in air by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow introduction.

    PubMed

    Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Yamashiro, Shigeharu; Sano, Yasuhiro; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Sekiguchi, Hiroyuki; Iura, Kazumitsu; Nagashima, Hisayuki; Nagoya, Tomoki; Tsuge, Kouichiro; Ohsawa, Isaac; Okumura, Akihiko; Takada, Yasuaki; Ezawa, Naoya; Watanabe, Susumu; Hashimoto, Hiroaki

    2014-05-01

    A highly sensitive and specific real-time field-deployable detection technology, based on counterflow air introduction atmospheric pressure chemical ionization, has been developed for a wide range of chemical warfare agents (CWAs) comprising gaseous (two blood agents, three choking agents), volatile (six nerve gases and one precursor agent, five blister agents), and nonvolatile (three lachrymators, three vomiting agents) agents in air. The approach can afford effective chemical ionization, in both positive and negative ion modes, for ion trap multiple-stage mass spectrometry (MS(n)). The volatile and nonvolatile CWAs tested provided characteristic ions, which were fragmented into MS(3) product ions in positive and negative ion modes. Portions of the fragment ions were assigned by laboratory hybrid mass spectrometry (MS) composed of linear ion trap and high-resolution mass spectrometers. Gaseous agents were detected by MS or MS(2) in negative ion mode. The limits of detection for a 1 s measurement were typically at or below the microgram per cubic meter level except for chloropicrin (submilligram per cubic meter). Matrix effects by gasoline vapor resulted in minimal false-positive signals for all the CWAs and some signal suppression in the case of mustard gas. The moisture level did influence the measurement of the CWAs. PMID:24678766

  13. Seasonal, anthropogenic, air mass, and meteorological influences on the atmospheric concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs): Evidence for the importance of diffuse combustion sources

    SciTech Connect

    Lee, R.G.M.; Green, N.J.L.; Lohmann, R.; Jones, K.C.

    1999-09-01

    Sampling programs were undertaken to establish air polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) concentrations at a semirural site on the northwest coast of England in autumn and summer and to investigate factors causing their variability. Changing source inputs, meteorological parameters, air masses, and the impact of a festival when it is customary to light fireworks and bonfires were investigated. Various lines of evidence from the study point to diffuse, combustion-related sources being a major influence on ambient air concentrations. Higher PCDD/F concentrations were generally associated with air masses that had originated and moved over land, particularly during periods of low ambient temperature. Low concentrations were associated with air masses that had arrived from the Atlantic Ocean/Irish Sea to the west of the sampling site and had little or no contact with urban/industrialized areas. Concentrations in the autumn months were 2 to 10 times higher than those found in the summer.

  14. Theoretical study of the effect of liquid desiccant mass flow rate on the performance of a cross flow parallel-plate liquid desiccant-air dehumidifier

    NASA Astrophysics Data System (ADS)

    Mohammad, Abdulrahman Th.; Mat, Sohif Bin; Sulaiman, M. Y.; Sopian, K.; Al-abidi, Abduljalil A.

    2013-11-01

    A computer simulation using MATLAB is investigated to predict the distribution of air stream parameters (humidity ratio and temperature) as well as desiccant parameters (temperature and concentration) inside the parallel plate absorber. The present absorber consists of fourteen parallel plates with a surface area per unit volume ratio of 80 m2/m3. Calcium chloride as a liquid desiccant flows through the top of the plates to the bottom while the air flows through the gap between the plates making it a cross flow configuration. The model results show the effect of desiccant mass flow rate on the performance of the dehumidifier (moisture removal and dehumidifier effectiveness). Performance comparisons between present cross-flow dehumidifier and another experimental cross-flow dehumidifier in the literature are carried out. The simulation is expected to help in optimizing of a cross flow dehumidifier.

  15. Combustion of a Methane-Air Mixture in a Slot Burner with an Inert Insert in Mass Transfer to the Environment

    NASA Astrophysics Data System (ADS)

    Krainov, A. Yu.; Moiseeva, K. M.

    2016-03-01

    A problem on combustion of a methane-air mixture in a slot burner with an internal insert in mass transfer from the burner's exterior wall to the environment has been solved. A mathematical formulation of the problem takes account of the dependence of the diffusion, thermal-conductivity, and heat-transfer coefficients on temperature, and also of the heat removal from the gas to the environment by convective and radiant heat transfer. A numerical investigation has been carried out in a one-dimensional mathematical formulation of the problem in dimensional variables. The boundary of existence of a stable high-temperature regime of combustion of the methane-air mixture has been determined as a function of the rate of feed of the gas, the environmental temperature, and the width of the flow area of the burner.

  16. Determination of seven pyrethroids biocides and their synergist in indoor air by thermal-desorption gas chromatography/mass spectrometry after sampling on Tenax TA ® passive tubes.

    PubMed

    Raeppel, Caroline; Appenzeller, Brice M; Millet, Maurice

    2015-01-01

    A method coupling thermal desorption and gas chromatography/mass spectrometry (GC/MS) was developed for the simultaneous determination of 7 pyrethroids (allethrin, bifenthrin, cyphenothrin, imiprothrin, permethrin, prallethrin and tetramethrin) and piperonyl butoxide adsorbed on Tenax TA(®) passive samplers after exposure in indoor air. Thermal desorption was selected as it permits efficient and rapid extraction without solvent used together with a good sensitivity. Detection (S/N>3) and quantification (S/N>10) limits varied between 0.001 ng and 2.5 ng and between 0.005 and 10 ng respectively with a reproducibility varied between 14% (bifenthrin) and 39% (permethrin). The method was used for the comparison indoor air contamination after low-pressure spraying and fumigation application in a rubbish chute situated in the basement of a building. PMID:25281107

  17. The effects of air mass transport, seasonality, and meteorology on pollutant levels at the Iskrba regional background station (1996-2014)

    NASA Astrophysics Data System (ADS)

    Poberžnik, Matevž; Štrumbelj, Erik

    2016-06-01

    Our main goal was to estimate the effects of long-range air transport on pollutant concentrations measured at the Iskrba regional background station (Slovenia). We cluster back-trajectories into categories and simultaneously model the effects of meteorology, seasonality, trends, and air mass trajectory clusters using a Bayesian statistical approach. This simplifies the interpretation of results and allows us to better identify the effects of individual variables, which is important, because pollutant concentrations, meteorology, and trajectories are seasonal and correlated. Similar to related work from other European sites, we find that slow and faster moving trajectories from eastern Europe and the northern part of the Balkan peninsula are associated with higher pollutant levels, while fast-moving trajectories from the Atlantic are associated with lower pollutant concentration. Overall, pollutant concentrations have decreased in the studied period.

  18. Large conversion rates of NO2 to HNO2 observed in air masses from the South China Sea: Evidence of strong production at sea surface?

    NASA Astrophysics Data System (ADS)

    Zha, Qiaozhi; Xue, Likun; Wang, Tao; Xu, Zheng; Yeung, Chungpong; Louie, Peter K. K.; Luk, Connie W. Y.

    2014-11-01

    Nitrous acid (HONO) plays important roles in tropospheric chemistry, but its source(s) are not completely understood. Here we analyze measurements of HONO, nitrogen dioxide (NO2), and related parameters at a coastal site in Hong Kong during September-December 2012. The nocturnal NO2-to-HONO conversion rates were estimated in air masses passing over land and sea surfaces. The conversion rates in the "sea cases" (3.17-3.36 × 10-2 h-1) were significantly higher than those in the "land cases" in our study (1.20-1.30 × 10-2 h-1) and in previous studies by others. These results suggest that air-sea interactions may be a significant source of atmospheric HONO and need to be considered in chemical transport models.

  19. HIGH PRECISION ISOTOPE RATIO MASS SPECTROMETRY METHOD FOR MEASURING THE O2/N2 RATIO OF AIR

    EPA Science Inventory

    Studies of the distribution of O2 in air will inform us about critical problems in the global carbon cycle which are not readily accessed by other measurements, including the rate of seasonal net production in the oceans on a hemispheric scale, the rate at which the oceans are ta...

  20. Determination of Hazardous Air Pollutant Surrogates Using Resonance Enhanced Multi Photon Ionization - Time of Flight Mass Spectrometry

    EPA Science Inventory

    EPA?s preferred approach for regulatory emissions compliance is based upon real-time monitoring of individual hazardous air pollutants (HAPs). Real-time, continuous monitoring not only provides the most comprehensive assurance of emissions compliance, but also can serve as a pro...

  1. Monitoring of Hazardous Air Pollutant Surrogates Using Resonance Enhanced Multiphoton Ionization/Time of Flight Mass Spectrometry

    EPA Science Inventory

    EPA’s preferred approach for regulatory emissions compliance is based upon real-time monitoring of individual hazardous air pollutants (HAPs). Real-time, continuous monitoring not only provides the most comprehensive assurance of emissions compliance, but also can serve as...

  2. Simulation of heat and mass transfer processes in the experimental section of the air-condensing unit of Scientific Production Company "Turbocon"

    NASA Astrophysics Data System (ADS)

    Artemov, V. I.; Minko, K. B.; Yan'kov, G. G.; Kiryukhin, A. V.

    2016-05-01

    A mathematical model was developed to be used for numerical analysis of heat and mass transfer processes in the experimental section of the air condenser (ESAC) created in the Scientific Production Company (SPC) "Turbocon" and mounted on the territory of the All-Russia Thermal Engineering Institute. The simulations were performed using the author's CFD code ANES. The verification of the models was carried out involving the experimental data obtained in the tests of ESAC. The operational capability of the proposed models to calculate the processes in steam-air mixture and cooling air and algorithms to take into account the maldistribution in the various rows of tube bundle was shown. Data on the influence of temperature and flow rate of the cooling air on the pressure in the upper header of ESAC, effective heat transfer coefficient, steam flow distribution by tube rows, and the dimensions of the ineffectively operating zones of tube bundle for two schemes of steam-air mixture flow (one-pass and two-pass ones) were presented. It was shown that the pressure behind the turbine (in the upper header) increases significantly at increase of the steam flow rate and reduction of the flow rate of cooling air and its temperature rise, and the maximum value of heat transfer coefficient is fully determined by the flow rate of cooling air. Furthermore, the steam flow rate corresponding to the maximum value of heat transfer coefficient substantially depends on the ambient temperature. The analysis of the effectiveness of the considered schemes of internal coolant flow was carried out, which showed that the two-pass scheme is more effective because it provides lower pressure in the upper header, despite the fact that its hydraulic resistance at fixed flow rate of steam-air mixture is considerably higher than at using the one-pass schema. This result is a consequence of the fact that, in the two-pass scheme, the condensation process involves the larger internal surface of tubes

  3. Design and preliminary tests of a blade tip air mass injection system for vortex modification and possible noise reduction on a full-scale helicopter rotor

    NASA Technical Reports Server (NTRS)

    Pegg, R. J.; Hosier, R. N.; Balcerak, J. C.; Johnson, H. K.

    1975-01-01

    Full-scale tests were conducted on the Langley helicopter rotor test facility as part of a study to evaluate the effectiveness of a turbulent blade tip air mass injection system in alleviating the impulsive noise (blade slap) caused by blade-vortex interaction. Although blade-slap conditions could not be induced during these tests, qualitative results from flow visualization studies using smoke showed that the differential velocity between the jet velocity and the rotor tip speed was a primary parameter controlling the vortex modification.

  4. Heat and mass transfer in a dissociated laminar boundary layer of air with consideration of the finite rate of chemical reaction

    NASA Technical Reports Server (NTRS)

    Oyegbesan, A. O.; Algermissen, J.

    1986-01-01

    A numerical investigation of heat and mass transfer in a dissociated laminar boundary layer of air on an isothermal flat plate is carried out for different degrees of cooling of the wall. A finite-difference chemical model is used to study elementary reactions involving NO2 and N2O. The analysis is based on equations of continuity, momentum, energy, conservation and state for the two-dimensional viscous flow of a reacting multicomponent mixtures. Attention is given to the effects of both catalyticity and noncatalyticity of the wall.

  5. Inter-annual variability of air mass and acidified pollutants transboundary exchange in the north-eastern part of the EANET region

    NASA Astrophysics Data System (ADS)

    Gromov, Sergey A.; Trifonova-Yakovleva, Alisa; Gromov, Sergey S.

    2016-04-01

    Anthropogenic emissions, be it exhaust gases or aerosols, stem from multitude of sources and may survive long-range transport within the air masses they were emitted into. So they follow regional and global transport pathways varying under different climatological regimes. Transboundary transfer of pollutants occurs this way and has a significant impact on the ecological situation of the territories neighbouring those of emission sources, as found in a few earlier studies examining the environmental monitoring data [1]. In this study, we employ a relatively facile though robust technique for estimating the transboundary air and concomitant pollutant fluxes using actual or climatological meteorological and air pollution monitoring data. Practically, we assume pollutant transfer being proportional to the horizontal transport of air enclosed in the lower troposphere and to the concentration of the pollutant of interest. The horizontal transport, in turn, is estimated using the mean layer wind direction and strength, or their descriptive statistics at the individual transects of the boundary of interest. The domain of our interest is the segment of Russian continental border in East Asia spanning from 88° E (southern Middle Siberia) to 135° E (Far East at Pacific shore). The data on atmospheric pollutants concentration are available from the Russian monitoring sites of the region-wide Acid Deposition Monitoring Network in East Asia (EANET, http://www.eanet.asia/) Mondy (Baikal area) and Primorskaya (near Vladivostok). The data comprises multi-year continuous measurement of gas-phase and particulate species abundances in air with at least biweekly sampling rate starting from 2000. In the first phase of our study, we used climatological dataset on winds derived from the aerological soundings at Russian stations along the continental border for the 10-year period (1961-1970) by the Research Institute of Hydrometeorological Information - World Data Centre (RIHMI-WDC) [3

  6. EVIDENCE OF FEED CONTAMINATION DUE TO SAMPLE HANDLING AND PREPARATION DURING A MASS BALANCE STUDY OF DIOXINS IN LACTATING COWS IN BACKGROUND CONDITIONS

    EPA Science Inventory

    In 1997, the United States (US) Environmental Protection Agency (EPA) conducted a mass balance study of polychlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs) in lactating cows in background conditions. The field portion of the study occurred at the US Department of A...

  7. On the possibility to discriminate the mass of the primary cosmic ray using the muon arrival times from extensive air showers: Application for Pierre Auger Observatory

    SciTech Connect

    Arsene, N.; Rebel, H.; Sima, O.

    2012-11-20

    In this paper we study the possibility to discriminate the mass of the primary cosmic ray by observing the muon arrival times in ground detectors. We analyzed extensive air showers (EAS) induced by proton and iron nuclei with the same energy 8 Multiplication-Sign 10{sup 17} eV simulated with CORSIKA, and analyzed the muon arrival times at ground measured by the infill array detectors of the Pierre Auger Observatory (PAO). From the arrival times of the core and of the muons the atmospheric depth of muon generation locus is evaluated. The results suggest a potential mass discrimination on the basis of muon arrival times and of the reconstructed atmospheric depth of muon production. An analysis of a larger set of CORSIKA simulations carried out for primary energies above 10{sup 18} eV is in progress.

  8. Sensitive method for quantification of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in end-exhaled air by thermal desorption gas chromatography mass spectrometry.

    PubMed

    Biesterbos, Jacqueline W H; Beckmann, Gwendolyn; Anzion, Rob B M; Ragas, Ad M J; Russel, Frans G M; Scheepers, Paul T J

    2014-06-17

    Octamethylcyclotetrasiloxane (D4) and decamethylpentasiloxane (D5) are used as ingredients for personal care products (PCPs). Because of the use of these PCPs, consumers are exposed daily to D4 and D5. A sensitive analytical method was developed for analysis of D4 and D5 in end-exhaled air by thermal desorption gas chromatography mass spectrometry (TD-GC-MS), to determine the internal dose for consumer exposure assessment. Fifteen consumers provided end-exhaled air samples that were collected using Bio-VOC breath samplers and subsequently transferred to automatic thermal desorption (ATD) tubes. Prior to use, the ATD tubes were conditioned for a minimum of 4 h at 350 °C. The TD unit and auto sampler were coupled to a GC-MS using electron ionization. Calibration was performed using 0-10 ng/μL solutions of D4/D5 and (13)C-labeled D4/D5 as internal standards. The ions monitored were m/z 281 for D4, 355 for D5, 285 for (13)C-labeled D4, and 360 for (13)C-labeled D5. The addition of internal standard reduced the coefficient of variation from 30.8% to 9.5% for D4 and from 37.8% to 12.5% for D5. The limit of quantification was 2.1 ng/L end-exhaled air for D4 and 1.4 ng/L end-exhaled air for D5. With this method, cyclic siloxanes (D4 and D5) can be quantified in end-exhaled air at concentrations as low as background levels observed in the general population. PMID:24833048

  9. Indications of photochemical histories of Pacific air masses from measurements of atmospheric trace species at Point Arena, California

    NASA Technical Reports Server (NTRS)

    Parrish, D. D.; Hahn, C. J.; Williams, E. J.; Norton, R. B.; Fehsenfeld, F. C.; Singh, H. B.; Shetter, J. D.; Gandrud, B. W.; Ridley, B. A.

    1992-01-01

    Measurements were made of a suite of photochemically active trace species (including light hydrocarbons, ozone, peroxyacetyl nitrate, HNO3, NO3(-), NO(x), and NO(y)) in marine air collected during a 10-day period in April and May 1985 at Point Arena (California), a coastal inflow site. It was found that the mixing ratios of the alkanes, ozone, peroxyacetyl nitrate, and HNO3 correlated with variations in the origins of calculated air parcel trajectories and with variations in the ratios of the light alkanes. The highest levels of alkanes and the photochemical products were found in parcels that had been rapidly transported across the North Pacific Ocean from near the 600-mbar level above the east Asian coast. It is suggested that production over the continents, transport to the marine areas, and parallel removal processes account for much of the observed correlation.

  10. Comparative analysis of dioxins and furans in ambient air by high-resolution and electron-capture mass spectrometry

    SciTech Connect

    Koester, C.J.; Harless, R.L.; Hites, R.A.

    1992-01-01

    Known mixtures and unknown atmospheric sample extracts containing polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) were analyzed by both electron impact, high resolution, mass spectrometry (HRMS) and by electron capture, negative ion, low resolution mass spectrometry (ECNI). PCDD/F concentrations measured by the two methods were comparable, typically agreeing with + or - 33%. The major difference between the two techniques is that HRMS easily detects 2,3,7,8- tetrachlorodibenzo-p-dioxin but ECNI does not. Results suggest that ECNI can be a sensitive low cost alternative to HRMS for the determination of PCDD/F concentrations.

  11. Occupational Exposure to Cobalt and Tungsten in the Swedish Hard Metal Industry: Air Concentrations of Particle Mass, Number, and Surface Area.

    PubMed

    Klasson, Maria; Bryngelsson, Ing-Liss; Pettersson, Carin; Husby, Bente; Arvidsson, Helena; Westberg, Håkan

    2016-07-01

    Exposure to cobalt in the hard metal industry entails severe adverse health effects, including lung cancer and hard metal fibrosis. The main aim of this study was to determine exposure air concentration levels of cobalt and tungsten for risk assessment and dose-response analysis in our medical investigations in a Swedish hard metal plant. We also present mass-based, particle surface area, and particle number air concentrations from stationary sampling and investigate the possibility of using these data as proxies for exposure measures in our study. Personal exposure full-shift measurements were performed for inhalable and total dust, cobalt, and tungsten, including personal real-time continuous monitoring of dust. Stationary measurements of inhalable and total dust, PM2.5, and PM10 was also performed and cobalt and tungsten levels were determined, as were air concentration of particle number and particle surface area of fine particles. The personal exposure levels of inhalable dust were consistently low (AM 0.15mg m(-3), range <0.023-3.0mg m(-3)) and below the present Swedish occupational exposure limit (OEL) of 10mg m(-3) The cobalt levels were low as well (AM 0.0030mg m(-3), range 0.000028-0.056mg m(-3)) and only 6% of the samples exceeded the Swedish OEL of 0.02mg m(-3) For continuous personal monitoring of dust exposure, the peaks ranged from 0.001 to 83mg m(-3) by work task. Stationary measurements showed lower average levels both for inhalable and total dust and cobalt. The particle number concentration of fine particles (AM 3000 p·cm(-3)) showed the highest levels at the departments of powder production, pressing and storage, and for the particle surface area concentrations (AM 7.6 µm(2)·cm(-3)) similar results were found. Correlating cobalt mass-based exposure measurements to cobalt stationary mass-based, particle area, and particle number concentrations by rank and department showed significant correlations for all measures except for particle number

  12. Occupational Exposure to Cobalt and Tungsten in the Swedish Hard Metal Industry: Air Concentrations of Particle Mass, Number, and Surface Area

    PubMed Central

    Bryngelsson, Ing-Liss; Pettersson, Carin; Husby, Bente; Arvidsson, Helena; Westberg, Håkan

    2016-01-01

    Exposure to cobalt in the hard metal industry entails severe adverse health effects, including lung cancer and hard metal fibrosis. The main aim of this study was to determine exposure air concentration levels of cobalt and tungsten for risk assessment and dose–response analysis in our medical investigations in a Swedish hard metal plant. We also present mass-based, particle surface area, and particle number air concentrations from stationary sampling and investigate the possibility of using these data as proxies for exposure measures in our study. Personal exposure full-shift measurements were performed for inhalable and total dust, cobalt, and tungsten, including personal real-time continuous monitoring of dust. Stationary measurements of inhalable and total dust, PM2.5, and PM10 was also performed and cobalt and tungsten levels were determined, as were air concentration of particle number and particle surface area of fine particles. The personal exposure levels of inhalable dust were consistently low (AM 0.15mg m−3, range <0.023–3.0mg m−3) and below the present Swedish occupational exposure limit (OEL) of 10mg m−3. The cobalt levels were low as well (AM 0.0030mg m−3, range 0.000028–0.056mg m−3) and only 6% of the samples exceeded the Swedish OEL of 0.02mg m−3. For continuous personal monitoring of dust exposure, the peaks ranged from 0.001 to 83mg m−3 by work task. Stationary measurements showed lower average levels both for inhalable and total dust and cobalt. The particle number concentration of fine particles (AM 3000 p·cm−3) showed the highest levels at the departments of powder production, pressing and storage, and for the particle surface area concentrations (AM 7.6 µm2·cm−3) similar results were found. Correlating cobalt mass-based exposure measurements to cobalt stationary mass-based, particle area, and particle number concentrations by rank and department showed significant correlations for all measures except for particle

  13. Interleukin 13– and interleukin 17A–induced pulmonary hypertension phenotype due to inhalation of antigen and fine particles from air pollution

    PubMed Central

    Park, Sung-Hyun; Chen, Wen-Chi; Esmaeil, Nafiseh; Lucas, Benjamin; Marsh, Leigh M.; Reibman, Joan

    2014-01-01

    Abstract Pulmonary hypertension has a marked detrimental effect on quality of life and life expectancy. In a mouse model of antigen-induced pulmonary arterial remodeling, we have recently shown that coexposure to urban ambient particulate matter (PM) significantly increased the thickening of the pulmonary arteries and also resulted in significantly increased right ventricular systolic pressures. Here we interrogate the mechanism and show that combined neutralization of interleukin 13 (IL-13) and IL-17A significantly ameliorated the increase in right ventricular systolic pressure, the circumferential muscularization of pulmonary arteries, and the molecular change in the right ventricle. Surprisingly, our data revealed a protective role of IL-17A for the antigen- and PM-induced severe thickening of pulmonary arteries. This protection was due to the inhibition of the effects of IL-13, which drove this response, and the expression of metalloelastase and resistin-like molecule α. However, the latter was redundant for the arterial thickening response. Anti-IL-13 exacerbated airway neutrophilia, which was due to a resulting excess effect of IL-17A, confirming concurrent cross inhibition of IL-13- and IL-17A-dependent responses in the lungs of animals exposed to antigen and PM. Our experiments also identified IL-13/IL-17A-independent molecular reprogramming in the lungs induced by exposure to antigen and PM, which indicates a risk for arterial remodeling and protection from arterial constriction. Our study points to IL-13- and IL-17A-coinduced inflammation as a new template for biomarkers and therapeutic targeting for the management of immune response–induced pulmonary hypertension. PMID:25610601

  14. Desert Dust Air Mass Mapping in the Western Sahara, using Particle Properties Derived from Space-based Multi-angle Imaging

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Fiebig, Marcus; Schladitz, Alexander; von Hoyningen-Huene, Wolfgang

    2008-01-01

    Coincident observations made over the Moroccan desert during the SAhara Mineral dUst experiMent (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from Multi-angle Imaging SpectroRadiometer (MISR) observations, and to place the sub-orbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days for which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 to 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR's ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape, and single-scattering albedo. For the three study days, the satellite observations (a) highlight regional gradients in the mix of dust and background spherical particles, (b) identify a dust plume most likely part of a density flow, and (c) show an air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometers away.

  15. Desert Dust Aerosol Air Mass Mapping in the Western Sahara, Using Particle Properties Derived from Space-Based Multi-Angle Imaging

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Esselborn, Michael; Fiebig, Marcus; Heese, Birgit; Knippertz, Peter; Mueller, Detlef; Schladitz, Alexander; Von Hoyningen-Huene, Wolfgang

    2008-01-01

    Coincident observations made over the Moroccan desert during the Sahara mineral dust experiment (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from multi-angle imaging spectroradiometer (MISR) observations, and to place the suborbital aerosol measurements into the satellite s larger regional context. On three moderately dusty days during which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR s ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape and single-scattering albedo. For the three study days, the satellite observations (1) highlight regional gradients in the mix of dust and background spherical particles, (2) identify a dust plume most likely part of a density flow and (3) show an aerosol air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometres away.

  16. Student Understanding of the Volume, Mass, and Pressure of Air within a Sealed Syringe in Different States of Compression.

    ERIC Educational Resources Information Center

    de Berg, Kevin Charles

    1995-01-01

    Investigation of (n=101) 17- to 18-year-old students' responses to a task relating to Boyle's Law for gases found that 34% to 38% of students did not understand the concepts of volume and mass, respectively, of a gas under the given circumstances. (Author/MKR)

  17. Chemical mass balance modeling for air quality analysis near a waste-to-energy facility in a complex urban area: Program design

    SciTech Connect

    Wells, R.; Watson, J.; Woy, J. van

    1997-12-31

    This paper describes the design and implementation of an ambient monitoring and receptor modeling study to evaluate air quality impacts from a state-of-the-art municipal waste management facility in a major urban area. The Robbins Resource Recovery Facility (RRRF), located in the Chicago metropolitan area, processes municipal solid waste (MSW) to recover recyclables, process the residual waste to create refuse-derived fuel (RDF), and burns the RDF to reduce the residual waste volume and recover energy. The RRRF is cooperating with the Illinois Environmental Protection Agency (IEPA) and the Illinois Office of the Attorney General (OAG) to analyze air quality and facility impacts in the plant vicinity. An ambient monitoring program began one year before plant operation and will continue for five years after startup. Because the impacts of the RRRF are projected to be very low, and because the Chicago area includes a complex mix of existing industrial, commercial, and residential activity, the ambient data will be analyzed using Version 7.0 of the USEPA s Chemical Mass Balance (CMB) model to estimate the extent of the RRRF`s impact on air quality in the area. The first year of pre-operational ambient data is currently under analysis. This paper describes the study design considerations, ambient monitoring program, emission data acquisition, background source data needs, and data analysis procedures developed to conduct CMB modeling in a complex industrialized area.

  18. Air temperature variability over three glaciers in the Ortles-Cevedale (Italian Alps): effects of glacier fragmentation, comparison of calculation methods, and impacts on mass balance modeling

    NASA Astrophysics Data System (ADS)

    Carturan, L.; Cazorzi, F.; De Blasi, F.; Dalla Fontana, G.

    2015-05-01

    Glacier mass balance models rely on accurate spatial calculation of input data, in particular air temperature. Lower temperatures (the so-called glacier cooling effect) and lower temperature variability (the so-called glacier damping effect) generally occur over glaciers compared to ambient conditions. These effects, which depend on the geometric characteristics of glaciers and display a high spatial and temporal variability, have been mostly investigated on medium to large glaciers so far, while observations on smaller ice bodies (< 0.5 km2) are scarce. Using a data set from eight on-glacier and four off-glacier weather stations, collected in the summers of 2010 and 2011, we analyzed the air temperature variability and wind regime over three different glaciers in the Ortles-Cevedale. The magnitude of the cooling effect and the occurrence of katabatic boundary layer (KBL) processes showed remarkable differences among the three ice bodies, suggesting the likely existence of important reinforcing mechanisms during glacier decay and fragmentation. The methods proposed by Greuell and Bohm (1998) and Shea and Moore (2010) for calculating on-glacier temperature from off-glacier data did not fully reproduce our observations. Among them, the more physically based procedure of Greuell and Bohm (1998) provided the best overall results where the KBL prevails, but it was not effective elsewhere (i.e., on smaller ice bodies and close to the glacier margins). The accuracy of air temperature estimations strongly impacted the results from a mass balance model which was applied to the three investigated glaciers. Most importantly, even small temperature deviations caused distortions in parameter calibration, thus compromising the model generalizability.

  19. Air temperature variability over three glaciers in the Ortles-Cevedale (Italian Alps): effects of glacier disintegration, intercomparison of calculation methods, and impacts on mass balance modeling

    NASA Astrophysics Data System (ADS)

    Carturan, L.; Cazorzi, F.; De Blasi, F.; Dalla Fontana, G.

    2014-12-01

    Glacier mass balance models rely on accurate spatial calculation of input data, in particular air temperature. Lower temperatures (the so-called glacier cooling effect), and lower temperature variability (the so-called glacier damping effect) generally occur over glaciers, compared to ambient conditions. These effects, which depend on the geometric characteristics of glaciers and display a high spatial and temporal variability, have been mostly investigated on medium- to large-size glaciers so far, while observations on smaller ice bodies are scarce. Using a dataset from 8 on-glacier and 4 off-glacier weather stations, collected in summer 2010 and 2011, we analyzed the air temperature variability and wind regime over three different glaciers in the Ortles-Cevedale. The magnitude of the cooling effect and the occurrence of katabatic boundary layer (KBL) processes showed remarkable differences among the three ice bodies, suggesting the likely existence of important reinforcing mechanisms during glacier decay and disintegration. None of the methods proposed in the literature for calculating on-glacier temperature from off-glacier data fully reproduced our observations. Among them, the more physically-based procedure of Greuell and Böhm (1998) provided the best overall results where the KBL prevail, but it was not effective elsewhere (i.e. on smaller ice bodies and close to the glacier margins). The accuracy of air temperature estimations strongly impacted the results from a mass balance model which was applied to the three investigated glaciers. Most importantly, even small temperature deviations caused distortions in parameter calibration, thus compromising the model generalizability.

  20. Back-trajectory modelling and DNA-based species-specific detection methods allow tracking of fungal spore transport in air masses.

    PubMed

    Grinn-Gofroń, Agnieszka; Sadyś, Magdalena; Kaczmarek, Joanna; Bednarz, Aleksandra; Pawłowska, Sylwia; Jedryczka, Malgorzata

    2016-11-15

    Recent advances in molecular detection of living organisms facilitate the introduction of novel methods to studies of the transport of fungal spores over large distances. Monitoring the migration of airborne fungi using microscope based spore identification is limited when different species produce very similar spores. In our study, DNA-based monitoring with the use of species-specific probes allowed us to track the aerial movements of two important fungal pathogens of oilseed rape (Brassica napus L.), i.e., Leptosphaeria maculans and Leptosphaeria biglobosa, which have identical spore shape and size. The fungi were identified using dual-labelled fluorescent probes that were targeted to a β-tubulin gene fragment of either Leptosphaeria species. Spore identification by Real-Time PCR techniques capable of detecting minute amounts of DNA of selected fungal species was combined with back-trajectory analysis, allowing the tracking of past movements of air masses using the Hybrid Single Particle Lagrangian Integrated Trajectory model. Over a study period spanning the previous decade (2006-2015) we investigated two specific events relating to the long distance transport of Leptosphaeria spp. spores to Szczecin in North-West Poland. Based on the above mentioned methods and the results obtained with the additional spore sampler located in nearby Szczecin, and operating at the ground level in an oilseed rape field, we have demonstrated that on both occasions the L. biglobosa spores originated from the Jutland Peninsula. This is the first successful attempt to combine analysis of back-trajectories of air masses with DNA-based identification of economically important pathogens of oilseed rape in Europe. In our studies, the timing of L. biglobosa ascospore dispersal in the air was unlikely to result in the infection of winter oilseed rape grown as a crop plant. However, the fungus could infect other host plants, such as vegetable brassicas, cruciferous weeds, spring rapeseed

  1. In-Line Ozonation for Sensitive Air-Monitoring of a Mustard-Gas Simulant by Atmospheric Pressure Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Okumura, Akihiko

    2015-09-01

    A highly sensitive method for real-time air-monitoring of mustard gas (bis(2-chloroethyl) sulfide, HD), which is a lethal blister agent, is proposed. Humidified air 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 concentration 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 gas was adequate to give a linear calibration curve for 2CEES obtained by detecting the MO2H+ signal in the concentration range up to 60 μg/m3, which is high enough for hygiene management. In the low concentration 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 air by using a simple and inexpensive home-made generator. 2CEES was ozonated in 1-m extended sampling tube in only 1 s.

  2. Dynamic behavior of air lubricated pivoted-pad journal-bearing, rotor system. 2: Pivot consideration and pad mass

    NASA Technical Reports Server (NTRS)

    Nemeth, Z. N.

    1972-01-01

    Rotor bearing dynamic tests were conducted with tilting-pad journal bearings having three different pad masses and two different pivot geometries. The rotor was vertically mounted and supported by two three-pad tilting-pad gas journal bearings and a simple externally pressurized thrust bearing. The bearing pads were 5.1 cm (2.02 in.) in diameter and 2.8 cm (1.5 in.) long. The length to diameter ratio was 0.75. One pad was mounted on a flexible diaphragm. The bearing supply pressure ranged from 0 to 690 kilonewtons per square meter (0 to 100 psig), and speeds ranged to 38,500 rpm. Heavy mass pad tilting-pad assemblies produced three rotor-bearing resonances above the first two rotor critical speeds. Lower supply pressure eliminated the resonances. The resonances were oriented primarily in the direction normal to the diaphragm.

  3. Associations between Prenatal traffic-related air pollution exposure and birth weight: Modification by sex and maternal pre-pregnancy body mass index

    PubMed Central

    Coull, Brent A.; Just, Allan C.; Maxwell, Sarah L.; Schwartz, Joel; Gryparis, Alexandros; Kloog, Itai; Wright, Rosalind J.; Wright, Robert O.

    2015-01-01

    Background Prenatal traffic-related air pollution exposure is linked to adverse birth outcomes. However, modifying effects of maternal body mass index (BMI) and infant sex remain virtually unexplored. Objectives We examined whether associations between prenatal air pollution and birth weight differed by sex and maternal BMI in 670 urban ethnically mixed mother-child pairs. Methods Black carbon (BC) levels were estimated using a validated spatio-temporal land-use regression (LUR) model; fine particulate matter (PM2.5) was estimated using a hybrid LUR model incorporating satellite-derived Aerosol Optical Depth measures. Using stratified multivariable-adjusted regression analyses, we examined whether associations between prenatal air pollution and calculated birth weight for gestational age (BWGA) z-scores varied by sex and maternal pre-pregnancy BMI. Results Median birth weight was 3.3±0.6 kg; 33% of mothers were obese (BMI ≥30 kg/m3). In stratified analyses, the association between higher PM2.5 and lower birth weight was significant in males of obese mothers (−0.42 unit of BWGA z-score change per IQR increase in PM2.5, 95%CI: −0.79 to −0.06) ( PM2.5 × sex × obesity Pinteraction=0.02). Results were similar for BC models (Pinteraction=0.002). Conclusions Associations of prenatal exposure to traffic-related air pollution and reduced birth weight were most evident in males born to obese mothers. PMID:25601728

  4. Mass of chlorinated volatile organic compounds removed by Pump-and-Treat, Naval Air Warfare Center, West Trenton, New Jersey, 1996-2010

    USGS Publications Warehouse

    Lacombe, Pierre J.

    2011-01-01

    Pump and Treat (P&T) remediation is the primary technique used to contain and remove trichloroethylene (TCE) and its degradation products cis 1-2,dichloroethylene (cDCE) and vinyl chloride (VC) from groundwater at the Naval Air Warfare Center (NAWC), West Trenton, NJ. Three methods were used to determine the masses of TCE, cDCE, and VC removed from groundwater by the P&T system since it became fully operational in 1996. Method 1, is based on the flow volume and concentrations of TCE, cDCE, and VC in groundwater that entered the P&T building as influent. Method 2 is based on withdrawal volume from each active recovery well and the concentrations of TCE, cDCE, and VC in the water samples from each well. Method 3 compares the maximum monthly amount of TCE, cDCE, and VC from Method 1 and Method 2. The greater of the two values is selected to represent the masses of TCE, cDCE and VC removed from groundwater each month. Previously published P&T monthly reports used Method 1 to determine the mass of TCE, cDCE, and VC removed. The reports state that 8,666 pounds (lbs) of TCE, 13,689 lbs of cDCE, and 2,455 lbs of VC were removed by the P&T system during 1996-2010. By using Method 2, the mass removed was determined to be 8,985 lbs of TCE, 17,801 lbs of cDCE, and 3,056 lbs of VC removed, and Method 3, resulted in 10,602 lbs of TCE, 21,029 lbs of cDCE, and 3,496 lbs of VC removed. To determine the mass of original TCE removed from groundwater, the individual masses of TCE, cDCE, and VC (determined using Methods 1, 2, and 3) were converted to numbers of moles, summed, and converted to pounds of original TCE. By using the molar conversion the mass of original TCE removed from groundwater by Methods 1, 2, and 3 was 32,381 lbs, 39,535 lbs, and 46,452 lbs, respectively, during 1996-2010. P&T monthly reports state that 24,805 lbs of summed TCE, cDCE, and VC were removed from groundwater. The simple summing method underestimates the mass of original TCE removed by the P&T system.

  5. Aerodynamical sealing by air curtains

    NASA Astrophysics Data System (ADS)

    Frank, Daria; Linden, Paul

    2015-11-01

    Air curtains are artificial high-velocity plane turbulent jets which are installed in a doorway in order to reduce the heat and the mass exchange between two environments. The performance of an air curtain is assessed in terms of the sealing effectiveness E, the fraction of the exchange flow prevented by the air curtain compared to the open-door situation. The main controlling parameter for air curtain dynamics is the deflection modulus Dm representing the ratio of the momentum flux of the air curtain and the transverse forces acting on it due to the stack effect. In this talk, we examine the influence of two factors on the performance of an air curtain: the presence of an additional ventilation pathway in the room, such as a small top opening, and the effects of an opposing buoyancy force which for example arises if a downwards blowing air curtain is heated. Small-scale experiments were conducted to investigate the E (Dm) -curve of an air curtain in both situations. We present both experimental results and theoretical explanations for our observations. We also briefly illustrate how simplified models developed for air curtains can be used for more complex phenomena such as the effects of wind blowing around a model building on the ventilation rates through the openings.

  6. Mass vaccination as a complementary tool in the control of a severe outbreak of bovine brucellosis due to Brucella abortus in Extremadura, Spain.

    PubMed

    Sanz, Cristina; Sáez, José Luis; Alvarez, Julio; Cortés, María; Pereira, Gema; Reyes, Aurelia; Rubio, Félix; Martín, Javier; García, Nerea; Domínguez, Lucas; Hermoso-de-Mendoza, María; Hermoso-de-Mendoza, Javier

    2010-11-01

    We report the evolution of an outbreak of bovine brucellosis (Brucella abortus) in the region of Extremadura (Spain) involving more than 1000 herds and nearly 40,000 animals. S19 vaccination of young cattle combined with a test and slaughter strategy did not result in a rapid decrease in herd prevalence and animal incidence; these parameters showed a constant decreasing trend only when a combination of restriction of cattle movements, increased test frequency, S19 vaccination and mass RB51 vaccination (with yearly revaccinations) were applied to all susceptible populations. These measures were applied for 5 years; abortions following RB51 vaccination of pregnant cows were limited to the first inoculation and the involvement of the vaccine strain could only be demonstrated in 78 out of 897 abortions. Our results demonstrate the usefulness - and lack of significant side effects - of RB51 mass vaccination as a complementary tool to control bovine brucellosis outbreaks in areas where the disease cannot be contained using more conservative approaches. PMID:20833439

  7. Decreased Osteoclastogenesis and High Bone Mass in Mice with Impaired Insulin Clearance Due to Liver-Specific Inactivation to CEACAM1

    PubMed Central

    Huang, S.; Kaw, M.; Harris, M.T.; Ebraheim, N.; McInerney, M.F.; Najjar, S.M.; Lecka-Czernik, B.

    2010-01-01

    Type 2 diabetes is associated with normal-to-higher bone mineral density (BMD) and increased rate of fracture. Hyperinsulinemia and hyperglycemia may affect bone mass and quality in the diabetic skeleton. In order to dissect the effect of hyperinsulinemia from the hyperglycemic impact on bone homeostasis, we have analyzed L-SACC1 mice, a murine model of impaired insulin clearance in liver causing hyperinsulinemia and insulin resistance without fasting hyperglycemia. Adult L-SACC1 mice exhibit significantly higher trabecular and cortical bone mass, attenuated bone formation as measured by dynamic histomorphometry, and reduced number of osteoclasts. Serum levels of bone formation (BALP) and bone resorption markers (TRAP5b and CTX) are decreased by approximately 50%. The L-SACC1 mutation in the liver affects myeloid cell lineage allocation in the bone marrow: the (CD3−CD11b−CD45R−) population of osteoclast progenitors is decreased by 40% and the number of (CD3−CD11b−CD45R+) B-cell progenitors is increased by 60%. L-SACC1 osteoclasts express lower levels of c-fos and RANK and their differentiation is impaired. In vitro analysis corroborated a negative effect of insulin on osteoclast recruitment, maturation and the expression levels of c-fos and RANK transcripts. Although bone formation is decreased in L-SACC1 mice, the differentiation potential and expression of the osteoblast-specific gene markers in L-SACC1-derived mesenchymal stem cells (MSC) remain unchanged as compared to the WT. Interestingly, however MSC from L-SACC1 mice exhibit increased PPARγ2 and decreased IGF-1 transcript levels. These data suggest that high bone mass in L-SACC1 animals results, at least in part, from a negative regulatory effect of insulin on bone resorption and formation, which leads to decreased bone turnover. Because low bone turnover contributes to decreased bone quality and an increased incidence of fractures, studies on L-SACC1 mice may advance our understanding of altered

  8. Xmaxμ vs. Nμ from extensive air showers as estimator for the mass of primary UHECR's. Application for the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Arsene, Nicusor; Sima, Octavian

    2015-02-01

    We study the possibility of primary mass estimation for Ultra High Energy Cosmic Rays (UHECR's) using the Xmaxμ (the height where the number of muons produced on the core of Extensive Air Showers (EAS) is maximum) and the number Nμ of muons detected on ground. We use the 2D distribution - Xmaxμ against Nμ in order to find its sensitivity to the mass of the primary particle. For that, we construct a 2D Probability Function Prob(p,Fe | Xmaxμ, Nμ) which estimates the probability that a certain point from the plane (Xmaxμ, Nμ) corresponds to a shower induced by a proton, respectively an iron nucleus. To test the procedure, we analyze a set of simulated EAS induced by protons and iron nuclei at energies of 1019eV and 20° zenith angle with CORSIKA. Using the Bayesian approach and taking into account the geometry of the infill detectors from the Pierre Auger Observatory, we observe an improvement in the accuracy of the primary mass reconstruction in comparison with the results obtained using only the Xmaxμ distributions.

  9. Direct AFM force measurements between air bubbles in aqueous polydisperse sodium poly(styrene sulfonate) solutions: effect of collision speed, polyelectrolyte concentration and molar mass.

    PubMed

    Browne, Christine; Tabor, Rico F; Grieser, Franz; Dagastine, Raymond R

    2015-07-01

    Interactions between colliding air bubbles in aqueous solutions of polydisperse sodium poly(styrene sulfonate) (NaPSS) using direct force measurements were studied. The forces measured with deformable interfaces were shown to be more sensitive to the presence of the polyelectrolytes when compared to similar measurements using rigid interfaces. The experimental factors that were examined were NaPSS concentration, bubble collision velocity and polyelectrolyte molar mass. These measurements were then compared with an analytical model based on polyelectrolyte scaling theory in order to explain the effects of concentration and bubble deformation on the interaction between bubbles. Typically structural forces from the presence of monodisperse polyelectrolyte between interacting surfaces may be expected, however, it was found that the polydispersity in molar mass resulted in the structural forces to be smoothed and only a depletion interaction was able to be measured between interacting bubbles. It was found that an increase in number density of NaPSS molecules resulted in an increase in the magnitude of the depletion interaction. Conversely this interaction was overwhelmed by an increase in the fluid flow in the system at higher bubble collision velocities. Polymer molar mass dispersity plays a significant role in the interactions present between the bubbles and has implications that also affect the polyelectrolyte overlap concentration of the solution. Further understanding of these implications can be expected to play a role in the improvement in operations in such fields as water treatment and mineral processing where polyelectrolytes are used extensively. PMID:25596872

  10. Two-dimensional two-phase mass transport model for methanol and water crossover in air-breathing direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Ye, Dingding; Zhu, Xun; Liao, Qiang; Li, Jun; Fu, Qian

    A two-dimensional two-phase mass transport model has been developed to predict methanol and water crossover in a semi-passive direct methanol fuel cell with an air-breathing cathode. The mass transport in the catalyst layer and the discontinuity in liquid saturation at the interface between the diffusion layer and catalyst layer are particularly considered. The modeling results agree well with the experimental data of a home-assembled cell. Further studies on the typical two-phase flow and mass transport distributions including species, pressure and liquid saturation in the membrane electrode assembly are investigated. Finally, the methanol crossover flux, the net water transport coefficient, the water crossover flux, and the total water flux at the cathode as well as their contributors are predicted with the present model. The numerical results indicate that diffusion predominates the methanol crossover at low current densities, while electro-osmosis is the dominator at high current densities. The total water flux at the cathode is originated primarily from the water generated by the oxidation reaction of the permeated methanol at low current densities, while the water crossover flux is the main source of the total water flux at high current densities.

  11. Combined deep sampling and mass-based approaches to assess soil carbon and nitrogen losses due to land-use changes in karst area of southwestern China

    NASA Astrophysics Data System (ADS)

    Hu, Yecui; Du, Zhangliu; Wang, Qibing; Li, Guichun

    2016-07-01

    The conversion of natural vegetation to human-managed ecosystems, especially the agricultural systems, may decrease soil organic carbon (SOC) and total nitrogen (TN) stocks. The objective of present study was to assess SOC and TN stocks losses by combining deep sampling with mass-based calculations upon land-use changes in a typical karst area of southwestern China. We quantified the changes from native forest to grassland, secondary shrub, eucalyptus plantation, sugarcane and corn fields (both defined as croplands), on the SOC and TN stocks down to 100 cm depth using fixed-depth (FD) and equivalent soil mass (ESM) approaches. The results showed that converting forest to cropland and other types significantly led to SOC and TN losses, but the extent depended on both sampling depths and calculation methods selected (i.e., FD or ESM). On average, the shifting from native forest to cropland led to SOC losses by 19.1, 25.1, 30.6, 36.8 and 37.9 % for the soil depths of 0-10, 0-20, 0-40, 0-60 and 0-100 cm, respectively, which highlighted that shallow sampling underestimated SOC losses. Moreover, the FD method underestimated SOC and TN losses for the upper 40 cm layer, but overestimated the losses in the deeper layers. We suggest that the ESM together with deep sampling should be encouraged to detect the differences in SOC stocks. In conclusion, the conversion of forest to managed systems, in particular croplands significantly decreased in SOC and TN stocks, although the effect magnitude to some extent depended on sampling depth and calculation approach selected.

  12. Application of high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for determination of chromium compounds in the air at the workplace.

    PubMed

    Stanislawska, Magdalena; Janasik, Beata; Wasowicz, Wojciech

    2013-12-15

    The toxicity and bioavailability of chromium species are highly dependable on the form or species, therefore determination of total chromium is insufficient for a complete toxicological evaluation and risk assessment. An analytical method for determination of soluble and insoluble Cr (III) and Cr (VI) compounds in welding fume at workplace air has been developed. The total chromium (Cr) was determined by using quadruple inductively coupled plasma mass spectrometry (ICP-MS) equipped with a dynamic reaction cell (DRC(®)). Soluble trivalent and hexavalent chromium compounds were determined by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A high-speed, reversed-phase CR C8 column (PerkinElmer, Inc., Shelton, CT, USA) was used for the speciation of soluble Cr (III) and soluble Cr (VI). The separation was accomplished by interaction of the chromium species with the different components of the mobile phase. Cr (III) formed a complex with EDTA, i.e. retained on the column, while Cr (VI) existed in the solutions as dichromate. Alkaline extraction (2% KOH and 3% Na2CO3) and anion exchange column (PRP-X100, PEEK, Hamilton) were used for the separation of the total Cr (VI). The results of the determination of Cr (VI) were confirmed by the analysis of the certified reference material BCR CRM 545 (Cr (VI) in welding dust). The results obtained for the certified material (40.2±0.6 g kg(-1)) and the values recorded in the examined samples (40.7±0.6 g kg(-1)) were highly consistent. This analytical method was applied for the determination of chromium in the samples in the workplace air collected onto glass (Whatman, Ø 37 mm) and membrane filters (Sartorius, 0.8 μm, Ø 37 mm). High performance liquid chromatography with inductively coupled plasma mass spectrometry is a remarkably powerful and versatile technique for determination of chromium species in welding fume at workplace air. PMID:24209303

  13. Internal jugular vein thrombosis presenting as a painful neck mass due to a spontaneous dislocated subclavian port catheter as long-term complication: a case report.

    PubMed

    Binnebösel, Marcel; Grommes, Jochen; Junge, Karsten; Göbner, Sonja; Schumpelick, Volker; Truong, Son

    2009-01-01

    Central venous access devices are extensively used for long-term chemotherapy and parenteral nutrition. However, there are some possible immediate, early, and late complications related to the implantation technique, care, and maintenance. We present the uncommon occurrence of a thrombosis of the internal jugular vein due to a spontaneous migration of a Port-A-Cath catheter into the ipsilateral internal jugular vein as a delayed complication of a central venous access catheter implanted for chemotherapy delivery. A review of the literature is given, and the factors responsible for this unusual complication will be discussed. PMID:19830037

  14. LIDAR technique: a central puzzle piece to build an integrated observation - modeling approach for air mass aerosols concentration evaluation

    NASA Astrophysics Data System (ADS)

    Tudose, Ovidiu-Gelu

    2013-04-01

    This paper presents a study of the temporal and vertical variation of mixed aerosol mass concentration near Bucharest during a dedicated observation campaign performed in summer 2012. To obtain the vertical mass concentrations profiles a combination of measured (mainly based on LIDAR technique) and modeled data was used. This method is based on the hypothesis that any mixture in the atmosphere can be described as a combination of low-depolarizing and high-depolarizing particles of a particular type. It uses the method proposed by Tesche et al. (2009), combined with forward simulations (i.e. OPAC). Based on supplementary information (e.g. preliminary assessment of aerosol source from forecast models and back trajectories) and several optical indicators (Angstrom exponent, LIDAR ratio, particle depolarization, AOD we built an approach to 2 cases of aerosol mixture, and validate the results using other information sources: sun photometry, forecasts, back trajectories. The first case was proved to be a smoke predominant layer, the second a Saharan dust predominant layer. Information from various data sources (DREAM, HYSPLIT, AERONET, MODIS) was consistent with our retrievals.

  15. Mass Sensor

    SciTech Connect

    Adams, B.E.

    2001-01-18

    The purpose of this CRADA was to use Honeywell's experience in low temperature cofire ceramics and traditional ceramics to assemble a relatively low-cost, mass-producible miniature mass analyzer. The specific design, given to us by Mass Sensors, LLC, was used to test for helium. The direct benefit for the participant was to have a prototype unit assembled for the purpose of proof of concept and the ability to secure venture capital investors. From that, the company would begin producing their own product for sale. The consumer/taxpayer benefits come from the wide variety of industries that can utilize this technology to improve quality of life. Medical industry can use this technology to improve diagnostic ability; manufacturing industry can use it for improved air, water, and soil monitoring to minimize pollution; and the law enforcement community can use this technology for identification of substances. These are just a few examples of the benefit of this technology. The benefits to DOE were in the area of process improvement for cofire and ceramic materials. From this project we demonstrated nonlinear thickfilm fine lines and spaces that were 5-mil wide with 5-mil spaces; determined height-to diameter-ratios for punched and filled via holes; demonstrated the ability to punch and fill 5-mil microvias; developed and demonstrated the capability to laser cut difficult geometries in 40-mil ceramic; developed and demonstrated coupling LTCC with standard alumina and achieving hermetic seals; developed and demonstrated three-dimensional electronic packaging concepts; and demonstrated printing variable resistors within 1% of the nominal value and within a tightly defined ratio. The capability of this device makes it invaluable for many industries. The device could be used to monitor air samples around manufacturing plants. It also could be used for monitoring automobile exhaust, for doing blood gas analysis, for sampling gases being emitted by volcanoes, for studying

  16. Development and Evaluation of an Externally Air-Cooled Low-Flow torch and the Attenuation of Space Charge and Matrix Effects in Inductively Coupled Plasma Mass Spectrometry

    SciTech Connect

    Praphairaksit, N.

    2000-09-12

    An externally air-cooled low-flow torch has been constructed and successfully demonstrated for applications in inductively coupled plasma mass spectrometry (ICP-MS). The torch is cooled by pressurized air flowing at {approximately}70 L/min through a quartz air jacket onto the exterior of the outer tube. The outer gas flow rate and operating RF forward power are reduced considerably. Although plasmas can be sustained at the operating power as low as 400 W with a 2 L/min of outer gas flow, somewhat higher power and outer gas flows are advisable. A stable and analytical useful plasma can be obtained at 850 W with an outer gas flow rate of {approximately}4 L/min. Under these conditions, the air-cooled plasma produces comparable sensitivities, doubly charged ion ratios, matrix effects and other analytical merits as those produced by a conventional torch while using significantly less argon and power requirements. Metal oxide ion ratios are slightly higher with the air-cooled plasma but can be mitigated by reducing the aerosol gas flow rate slightly with only minor sacrifice in analyte sensitivity. A methodology to alleviate the space charge and matrix effects in ICP-MS has been developed. A supplemental electron source adapted from a conventional electron impact ionizer is added to the base of the skimmer. Electrons supplied from this source downstream of the skimmer with suitable amount and energy can neutralize the positive ions in the beam extracted from the plasma and diminish the space charge repulsion between them. As a result, the overall ion transmission efficiency and consequent analyte ion sensitivities are significantly improved while other important analytical aspects, such as metal oxide ion ratio, doubly charged ion ratio and background ions remain relatively unchanged with the operation of this electron source. This technique not only improves the ion transmission efficiency but also minimizes the matrix effects drastically. The matrix-induced suppression

  17. Thermally-driven advections of aerosol-rich air masses to an Alpine valley: Theoretical considerations and experimental evidences

    NASA Astrophysics Data System (ADS)

    Diémoz, Henri; Magri, Tiziana; Pession, Giordano; Zublena, Manuela; Campanelli, Monica; Gobbi, Gian Paolo; Barnaba, Francesca; Di Liberto, Luca; Dionisi, Davide

    2016-04-01

    A CHM-15k laser radar (lidar) was installed in April 2015 at the solar observatory of the Environmental Protection Agency (ARPA) of the Aosta Valley (Northern Italy, 45.74N, 7.36E, 560 m a.s.l.). The instrument operates at 1064 nm, is capable of mapping the vertical profile of aerosols and clouds up to the tropopause and is part of the Alice-net ceilometers network (www.alice-net.eu). The site is in a large Alpine valley floor, in a semi-rural context. Among the most interesting cases observed in the first months of operation, several days characterised by weak synoptic circulation and well-developed, thermally-driven up-valley winds are accompanied by the appearance of a thick aerosol layer in the afternoon. The phenomenon is frequent in Spring and Summer and is likely to be related to easterly airmass advections from polluted sites (e.g., the Po basin) rather than to local emissions. To test this hypothesis, the following method was adopted. First, some case studies were selected and the respective meteorological fields were analysed based on both observations at ground and the high-resolution output of the nonhydrostatic limited-area atmospheric prediction model maintained by the COnsortium for Small-scale MOdelling (COSMO) over the complex orography of the domain. Then, to evaluate the dynamics of the aerosol diffusion in the valley, the chemical transport 2D/3D eulerian Flexible Air quality Regional Model (FARM) was run. Finally, the three-dimensional output of the model was compared to the vertically-resolved aerosol field derived from the lidar-ceilometer soundings. The effects of up-slope winds, and the resulting subsidence along the main axis of the valley, is hypothesised to break up the aerosol layer close to the ground in the middle of the day and to drag the residual layer down into the mixing layer. The measurements by a co-located sun/sky photometer operating in the framework of the EuroSkyRad (ESR) network were additionally analysed to detect any

  18. Evaluation of chemical transport model predictions of primary organic aerosol for air masses classified by particle-component-based factor analysis

    NASA Astrophysics Data System (ADS)

    Stroud, C. A.; Moran, M. D.; Makar, P. A.; Gong, S.; Gong, W.; Zhang, J.; Slowik, J. G.; Abbatt, J. P. D.; Lu, G.; Brook, J. R.; Mihele, C.; Li, Q.; Sills, D.; Strawbridge, K. B.; McGuire, M. L.; Evans, G. J.

    2012-02-01

    Observations from the 2007 Border Air Quality and Meteorology Study (BAQS-Met 2007) in southern Ontario (ON), Canada, were used to evaluate Environment Canada's regional chemical transport model predictions of primary organic aerosol (POA). Environment Canada's operational numerical weather prediction model and the 2006 Canadian and 2005 US national emissions inventories were used as input to the chemical transport model (named AURAMS). Particle-component-based factor analysis was applied to aerosol mass spectrometer measurements made at one urban site (Windsor, ON) and two rural sites (Harrow and Bear Creek, ON) to derive hydrocarbon-like organic aerosol (HOA) factors. Co-located carbon monoxide (CO), PM2.5 black carbon (BC), and PM1 SO4 measurements were also used for evaluation and interpretation, permitting a detailed diagnostic model evaluation. At the urban site, good agreement was observed for the comparison of daytime campaign PM1 POA and HOA mean values: 1.1 μg m-3 vs. 1.2 μg m-3, respectively. However, a POA overprediction was evident on calm nights due to an overly-stable model surface layer. Biases in model POA predictions trended from positive to negative with increasing HOA values. This trend has several possible explanations, including (1) underweighting of urban locations in particulate matter (PM) spatial surrogate fields, (2) overly-coarse model grid spacing for resolving urban-scale sources, and (3) lack of a model particle POA evaporation process during dilution of vehicular POA tail-pipe emissions to urban scales. Furthermore, a trend in POA bias was observed at the urban site as a function of the BC/HOA ratio, suggesting a possible association of POA underprediction for diesel combustion sources. For several time periods, POA overprediction was also observed for sulphate-rich plumes, suggesting that our model POA fractions for the PM2.5 chemical speciation profiles may be too high for these point sources. At the rural Harrow site

  19. Optimisation of sorbent trapping and thermal desorption-gas chromatography-mass spectrometric conditions for sampling and analysis of hydrogen cyanide in air.

    PubMed

    Juillet, Yannick; Le Moullec, Sophie; Bégos, Arlette; Bellier, Bruno

    2005-06-01

    Among the chemicals belonging to the schedules of the Chemical Weapons Convention (CWC), sampling and analysis of highly volatile compounds such as hydrogen cyanide (HCN) require special consideration. The latter is present in numerous old chemical weapons that are stockpiled awaiting destruction in Northeastern France: thus, sampling on stockpile area and subsequent verification of HCN levels is compulsory to ensure safety of workers on these areas. The ability of several commercial sorbents to trap hydrogen cyanide at various concentration levels and in various humidity conditions, was evaluated. Furthermore, thermal desorption of the corresponding samples, followed by analysis by gas chromatography-mass spectrometry was also optimised. Carbosieve S-III, a molecular sieve possessing a very high specific area, proved the most efficient sorbent for HCN sampling in all conditions tested. Conversely, the presented results show that Tenax, albeit generally considered as the reference sorbent for air monitoring and analysis of CWC-related chemicals, is not suitable for HCN trapping. PMID:15912249

  20. A high-fidelity multiphysics model for the new solid oxide iron-air redox battery. part I: Bridging mass transport and charge transfer with redox cycle kinetics

    NASA Astrophysics Data System (ADS)

    Jin, Xinfang; Zhao, Xuan; Huang, Kevin

    2015-04-01

    A high-fidelity two-dimensional axial symmetrical multi-physics model is described in this paper as an effort to simulate the cycle performance of a recently discovered solid oxide metal-air redox battery (SOMARB). The model collectively considers mass transport, charge transfer and chemical redox cycle kinetics occurring across the components of the battery, and is validated by experimental data obtained from independent research. In particular, the redox kinetics at the energy storage unit is well represented by Johnson-Mehl-Avrami-Kolmogorov (JMAK) and Shrinking Core models. The results explicitly show that the reduction of Fe3O4 during the charging cycle limits the overall performance. Distributions of electrode potential, overpotential, Nernst potential, and H2/H2O-concentration across various components of the battery are also systematically investigated.

  1. Dynamics of the flammable plumes resulting from the convective dispersion of a fixed mass of the buoyant gaseous fuel, methane, into air.

    PubMed

    Fardisi, S; Karim, Ghazi A

    2009-08-15

    The dynamics of the dispersion of a fixed mass of the buoyant fuel, methane, when exposed with a negligible pressure difference to overlaying air within vertical cylindrical enclosures open to the atmosphere is investigated. Features of the formation and dispersion of flammable mixtures created by the gas dissipation were examined using a 3D CFD model. For the cases considered, the lean-flammable mixture boundary appears to travel mainly at a near constant rate while the rich limit front shows a more chaotic behaviour. The corresponding simulation using an axis-symmetrical 2D model tended to under-predict the dynamics of the lean and rich boundaries, for the cases considered. PMID:19237243

  2. Simultaneous heat and mass transfer inside a vertical tube in evaporating a heated falling alcohols liquid film into a stream of dry air

    NASA Astrophysics Data System (ADS)

    Senhaji, S.; Feddaoui, M.; Mediouni, T.; Mir, A.

    2009-03-01

    A numerical study of the evaporation in mixed convection of a pure alcohol liquid film: ethanol and methanol was investigated. It is a turbulent liquid film falling on the internal face of a vertical tube. A laminar flow of dry air enters the vertical tube at constant temperature in the downward direction. The wall of the tube is subjected to a constant and uniform heat flux. The model solves the coupled parabolic governing equations in both phases including turbulent liquid film together with the boundary and interfacial conditions. The systems of equations obtained by using an implicit finite difference method are solved by TDMA method. A Van Driest model is adopted to simulate the turbulent liquid film flow. The influence of the inlet liquid flow, Reynolds number in the gas flow and the wall heat flux on the intensity of heat and mass transfers are examined. A comparison between the results obtained for studied alcohols and water in the same conditions is made.

  3. Engineering correlations of variable-property effects on laminar forced convection mass transfer for dilute vapor species and small particles in air

    NASA Technical Reports Server (NTRS)

    Gokoglu, S. A.; Rosner, D. E.

    1984-01-01

    A simple engineering correlation scheme is developed to predict the variable property effects on dilute species laminar forced convection mass transfer applicable to all vapor molecules or Brownian diffusing small particle, covering the surface to mainstream temperature ratio of 0.25 T sub W/T sub e 4. The accuracy of the correlation is checked against rigorous numerical forced convection laminar boundary layer calculations of flat plate and stagnation point flows of air containing trace species of Na, NaCl, NaOH, Na2SO4, K, KCl, KOH, or K2SO4 vapor species or their clusters. For the cases reported here the correlation had an average absolute error of only 1 percent (maximum 13 percent) as compared to an average absolute error of 18 percent (maximum 54 percent) one would have made by using the constant-property results.

  4. A high-fidelity multiphysics model for the new solid oxide iron-air redox battery part I: Bridging mass transport and charge transfer with redox cycle kinetics

    SciTech Connect

    Jin, XF; Zhao, X; Huang, K

    2015-04-15

    A high-fidelity two-dimensional axial symmetrical multi-physics model is described in this paper as an effort to simulate the cycle performance of a recently discovered solid oxide metal-air redox battery (SOMARB). The model collectively considers mass transport, charge transfer and chemical redox cycle kinetics occurring across the components of the battery, and is validated by experimental data obtained from independent research. In particular, the redox kinetics at the energy storage unit is well represented by Johnson-Mehl-Avrami-Kolmogorov (JIVIAK) and Shrinking Core models. The results explicitly show that the reduction of Fe3O4 during the charging cycle limits the overall performance. Distributions of electrode potential, overpotential, Nernst potential, and H-2/H2O-concentration across various components of the battery are also systematically investigated. (C) 2015 Elsevier B.V. All rights reserved.

  5. Design, Modeling, Fabrication, and Evaluation of the Air Amplifier for Improved Detection of Biomolecules by Electrospray Ionization Mass Spectrometry

    PubMed Central

    Robichaud, Guillaume; Dixon, R. Brent; Potturi, Amarnatha S.; Cassidy, Dan; Edwards, Jack R.; Sohn, Alex; Dow, Thomas A.; Muddiman, David C.

    2010-01-01

    Through a multi-disciplinary approach, the air amplifier is being evolved as a highly engineered device to improve detection limits of biomolecules when using electrospray ionization. Several key aspects have driven the modifications to the device through experimentation and simulations. We have developed a computer simulation that accurately portrays actual conditions and the results from these simulations are corroborated by the experimental data. These computer simulations can be used to predict outcomes from future designs resulting in a design process that is efficient in terms of financial cost and time. We have fabricated a new device with annular gap control over a range of 50 to 70 μm using piezoelectric actuators. This has enabled us to obtain better aerodynamic performance when compared to the previous design (2× more vacuum) and also more reproducible results. This is allowing us to study a broader experimental space than the previous design which is critical in guiding future directions. This work also presents and explains the principles behind a fractional factorial design of experiments methodology for testing a large number of experimental parameters in an orderly and efficient manner to understand and optimize the critical parameters that lead to obtain improved detection limits while minimizing the number of experiments performed. Preliminary results showed that several folds of improvements could be obtained for certain condition of operations (up to 34 folds). PMID:21499524

  6. Mass loading of size-segregated atmospheric aerosols in the ambient air during fireworks episodes in eastern Central India.

    PubMed

    Nirmalkar, Jayant; Deb, Manas K; Deshmukh, Dhananjay K; Verma, Santosh K

    2013-04-01

    The effects of combustion of the fire crackers on the air quality in eastern Central India were studied for the first time during Diwali festival. This case study analyzes the size distribution and temporal variation of aerosols collected in the rural area of eastern Central India during pre-diwali, Diwali and post-diwali period for the year of 2011. Fifteen aerosol samples were collected during the special case study of Diwali period using Andersen sampler. The mean concentrations of PM10 (respirable particulate matter) were found to be 212.8 ± 4.2, 555.5 ± 20.2 and 284.4 ± 5.8 during pre-diwali, Diwali and post-diwali period, respectively. During Diwali festival PM10 concentration was about 2.6 and 1.9 times higher than pre-diwali and post-diwali period, respectively. PM2.5 (fine) and PM1 (submicron) concentrations during Diwali festival were more than 2 times higher than pre-diwali and post-diwali. PMID:23287842

  7. Comparison of negative-ion proton-transfer with iodide ion chemical ionization mass spectrometry for quantification of isocyanic acid in ambient air

    NASA Astrophysics Data System (ADS)

    Woodward-Massey, Robert; Taha, Youssef M.; Moussa, Samar G.; Osthoff, Hans D.

    2014-12-01

    Isocyanic acid (HNCO) is a trace gas pollutant of potential importance to human health whose measurement has recently become possible through the development of negative-ion proton-transfer chemical ionization mass spectrometry (NI-PT-CIMS) with acetate reagent ion. In this manuscript, an alternative ionization and detection scheme, in which HNCO is quantified by iodide CIMS (iCIMS) as a cluster ion at m/z 170, is described. The sensitivity was inversely proportional to water vapor concentration but could be made independent of humidity changes in the sampled air by humidifying the ion-molecule reaction (IMR) region of the CIMS. The performance of the two ionization schemes was compared and contrasted using ambient air measurements of HNCO mixing ratios in Calgary, AB, Canada, by NI-PT-CIMS with acetate reagent ion from Dec 16 to 20, 2013, and by the same CIMS operated in iCIMS mode from Feb 3 to 7, 2014. The iCIMS exhibited a greater signal-to-noise ratio than the NI-PT-CIMS, not because of its sensitivity, which was lower (˜0.083 normalized counts per second (NCPS) per parts-per-trillion by volume (pptv) compared to ˜9.7 NCPS pptv-1), but because of a much lower and more stable background (3 ± 4 compared to a range of ˜2 × 103 to ˜6 × 103 NCPS). For the Feb 2014 data set, the HNCO mixing ratios in Calgary air ranged from <12 to 94 pptv (median 34 pptv), were marginally higher at night than during day, and correlated with nitrogen oxide (NOx = NO + NO2) mixing ratios and submicron particle volume. The ratios of HNCO to NOx observed are within the range of emission ratios reported for gasoline-powered motor vehicles.

  8. Molecular characterisation of organic material in air fine particles (PM10) using conventional and reactive pyrolysis-gas chromatography-mass spectrometry.

    PubMed

    Fabbri, Daniele; Prati, Silvia; Vassura, Ivano

    2002-04-01

    Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) was applied to study the composition of organic constituents in air particulate matter (PM10) collected inside an industrial area. A few milligrams of sampling filters containing air particles were pyrolysed at 700 degrees C directly (conventional) or after the addition of a derivatising reagent (tetramethylammonium hydroxide, TMAH, for pyrolysis-methylation; hexamethyldisilazane, HMDS, for pyrolysis-silylation). Py-GC-MS was also applied to synthetic polymers (poly(styrene-co-isoprene), polylimonene and polypinene) and vegetation samples (coniferous pollen, bark and resin) to identify markers indicative of possible precursors. Pyrolysates of PM10 showed the same suite of compounds in all the four seasons, dominated by hydrocarbons like styrene, limonene and clusters of isomeric alkenes with 14, 15 and 16 carbon atoms. Pyrolysis products of natural origin, including furaldehyde, benzeneacetonitrile, dehydroabietin and other diterpenoids were found, while no specific markers of synthetic rubbers were detected. The principal products released from reactive pyrolysis of PM10 were methyl or trimethylsilyl (TMS) derivatives of 1,6-anhydroglucose (levoglucosan), fatty acids, dehydroabietic acid and other resin acids along with hydroxy (di)carboxylic acids. Possible sources of the detected products (e.g. pine forest, biomass combustion) are discussed. PMID:11993758

  9. Results from an International Measurement Round Robin of III-V Triple Junction Solar Cells under Air Mass Zero

    NASA Technical Reports Server (NTRS)

    Jenkins, Phillip; Scheiman, Chris; Goodbody, Chris; Baur, Carsten; Sharps, Paul; Imaizumi, Mitsuru; Yoo, Henry; Sahlstrom, Ted; Walters, Robert; Lorentzen, Justin; Nocerino, John; Khan, Osman; Cravens, Robert; Valles, Juan; Toporow, Chantal; Gomez, Trinidad,; Bazan, Loreto Pazos; Bailey, Sheila

    2006-01-01

    This paper reports the results of an international measurement round robin of monolithic, triple-junction, GaInP/GaAs/Ge space solar cells. Eight laboratories representing national labs, solar cell vendors and space solar cell consumers, measured cells using in-house reference cells and compared those results to measurements made where each lab used the same set of reference cells. The results show that most of the discrepancy between laboratories is likely due to the quality of the standard cells rather than the measurement system or solar simulator used.

  10. Assessing Patterns in the Surface Electric Field Prior to First CG Flashes and After Last CG Flashes in Air-Mass Thunderstorms

    NASA Astrophysics Data System (ADS)

    Williams, D. E.; Beasley, W. H.; Hyland, P. T.

    2007-12-01

    In an effort to elicit patterns in the temporal and spatial evolution of the contours of surface electric field relevant to the occurrence of cloud-to-ground (CG) lightning, we have analyzed data from the network of 31 electric-field mills jointly operated by the John F. Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). To identify cases of interest, we used lightning ground-strike data, maps of in-cloud lightning discharges, rainfall data, and radar data. In particular, we have focused on two critical problems: 1) estimation of when and where the first CG flash in a storm might occur and 2) assessment of the likelihood of CG flashes occurring late in a storm after a long period without a CG flash. Our long-term goal is to understand the evolution of surface contours of electric field for periods of 30 minutes or more before the first flash of any kind and 30 minutes or more before and after the last flash of any kind. For practical reasons, we are reporting here on analysis of data for periods of 30 minutes before the first CG flash and 30 minutes after the last CG flash in each storm of interest. We have analyzed electric-field data from isolated air-mass convective storms that developed over KSC/CCAFS from late May through early September, 2004-2006. To identify thunderstorms that fit the air-mass, or "pop-up" criteria, we started by examining rainfall and CG lightning data, then looked at radar data. Then, for the storms selected, we performed a two-pass Barnes objective analysis on the electric-field data. Each analysis cycle resulted in one contour plot of 20-second averaged data, yielding 90 plots for each 30 minute interval, which we then animated. This resulted in 58 animations of the field contours prior to first CG flashes and 62 animations of the field contours after last CG flashes. Preliminary impressions from examinations of these cases suggest that the electric-field contours before the first flash exhibit a smooth transition

  11. Analysis of air-mass modification over Poland and Romania by means of multiwavelength lidars - a case study 19-21/07/2014

    NASA Astrophysics Data System (ADS)

    Costa-Surós, Montserrat; Stachlewska, Iwona S.; Nicolae, Doina; Nemuc, Anca; Janicka, Lucja; Markowicz, Krzysztof M.; Belegante, Livio; Talianu, Camelia; Heese, Birgit; Engelmann, Ronny

    2015-04-01

    A case study of air-mass modification over Poland and Romania, assessing the role of the Carpathian Mountains, during 19-21/07/2014 is analyzed. The study is based mainly on measurements taken by two multiwavelength Raman lidars at two different sites: the Radiative Transfer Laboratory (RT-Lab) at the Faculty of Physics of the University of Warsaw in Warsaw (Poland) and at the RADO site of the National Institute of R&D in Optoelectronics in Magurele (Romania). These data were complemented with meteorological data collected at two other sites: SolarAOT in Strzyżów (Poland) - equipped also with AERONET photometer and CHM15k ceilometer, and in Cluj (Romania). The RADO site, with its 7-wavelength aerosol-Raman-depolarization lidar (RALi) is integrated into EARLINET network. The RT-Lab site, with its 8-wavelength aerosol-Raman-depolarization (PollyXT-type) lidar, started the procedure to join in EARLINET last year. Moreover, RT-Lab and SolarAOT sites are part of the Poland AOD network. The analysis is focused on evaluating both multi-wavelength lidar data sets in order to search for similarities and differences in the vertical profiles describing the atmospheric layers above the two stations. Accordingly to GDAS Hysplit 4-days backward trajectory ending up in Magurele at 0.5, 1.5 and 3 km an air-mass from western Europe entered Poland from the north-west on 19/07/2014, descended on the following day over the Poland AOD station in Strzyżów, followed by Cluj and end up at Magurele on 21/07/2014. As the four stations are located along a north-west to south-east line the objective was to evaluate the aerosol properties of the air flow transported over Poland and further to Romania. At both sites, backscatter profiles at 355, 532 and 1064nm, extinction profiles at 355 and 532nm, and depolarization profiles at 532nm and 355nm, show distinctly layered structure in the atmosphere. Along with these we used data from stations in Strzyżów and Cluj as well as information

  12. A Longitudinal Cohort Study of Body Mass Index and Childhood Exposure to Secondhand Tobacco Smoke and Air Pollution: The Southern California Children’s Health Study

    PubMed Central

    Shen, Ernest; Gilliland, Frank D.; Jerrett, Michael; Wolch, Jennifer; Chang, Chih-Chieh; Lurmann, Frederick; Berhane, Kiros

    2014-01-01

    Background: Childhood body mass index (BMI) and obesity prevalence have been associated with exposure to secondhand smoke (SHS), maternal smoking during pregnancy, and vehicular air pollution. There has been little previous study of joint BMI effects of air pollution and tobacco smoke exposure. Methods: Information on exposure to SHS and maternal smoking during pregnancy was collected on 3,318 participants at enrollment into the Southern California Children’s Health Study. At study entry at average age of 10 years, residential near-roadway pollution exposure (NRP) was estimated based on a line source dispersion model accounting for traffic volume, proximity, and meteorology. Lifetime exposure to tobacco smoke was assessed by parent questionnaire. Associations with subsequent BMI growth trajectory based on annual measurements and attained BMI at 18 years of age were assessed using a multilevel modeling strategy. Results: Maternal smoking during pregnancy was associated with estimated BMI growth over 8-year follow-up (0.72 kg/m2 higher; 95% CI: 0.14, 1.31) and attained BMI (1.14 kg/m2 higher; 95% CI: 0.66, 1.62). SHS exposure before enrollment was positively associated with BMI growth (0.81 kg/m2 higher; 95% CI: 0.36, 1.27) and attained BMI (1.23 kg/m2 higher; 95% CI: 0.86, 1.61). Growth and attained BMI increased with more smokers in the home. Compared with children without a history of SHS and NRP below the median, attained BMI was 0.80 kg/m2 higher (95% CI: 0.27, 1.32) with exposure to high NRP without SHS; 0.85 kg/m2 higher (95% CI: 0.43, 1.28) with low NRP and a history of SHS; and 2.15 kg/m2 higher (95% CI: 1.52, 2.77) with high NRP and a history of SHS (interaction p-value 0.007). These results suggest a synergistic effect. Conclusions: Our findings strengthen emerging evidence that exposure to tobacco smoke and NRP contribute to development of childhood obesity and suggest that combined exposures may have synergistic effects. Citation: McConnell R, Shen E

  13. Determining the levels of volatile organic pollutants in urban air using a gas chromatography-mass spectrometry method.

    PubMed

    Nicoara, Simona; Tonidandel, Loris; Traldi, Pietro; Watson, Jonathan; Morgan, Geraint; Popa, Ovidiu

    2009-01-01

    The paper presents the application of a method based on coupled gas chromatography-mass spectrometry, using an isotopically labelled internal standard for the quantitative analysis of benzene (B), toluene (T), ethyl benzene (E), and o-, m-, p-xylenes (X). Their atmospheric concentrations were determined based on short-term sampling, in different sites of Cluj-Napoca, a highly populated urban centre in N-W Romania, with numerous and diversified road vehicles with internal combustion engines. The method is relatively inexpensive and simple and shows good precision and linearity in the ranges of 7-60 mug/m(3) (B), 13-90 mug/m(3) (T), 7-50 mug/m(3) (E), 10-70 mug/m(3) (X-m,p), and 20-130 mug/m(3) (X-o). The limits of quantitation/detection of the method LOQ/LOD are of 10/5 mug/m(3) (Xo), 5/3 mug/m(3) (B, E, X-m,p), and of 3/1 mug/m(3) (T), respectively. PMID:20168976

  14. 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

  15. Use of proton-transfer-reaction mass spectrometry to characterize volatile organic compound sources at the La Porte super site during the Texas Air Quality Study 2000

    NASA Astrophysics Data System (ADS)

    Karl, Thomas; Jobson, Tom; Kuster, William C.; Williams, Eric; Stutz, Jochen; Shetter, Rick; Hall, Samuel R.; Goldan, Paul; Fehsenfeld, Fred; Lindinger, Werner

    2003-08-01

    Proton-transfer-reaction mass spectrometry (PTR-MS) was deployed for continuous real-time monitoring of volatile organic compounds (VOCs) at a site near the Houston Ship Channel during the Texas Air Quality Study 2000. Overall, 28 ions dominated the PTR-MS mass spectra and were assigned as anthropogenic aromatics (e.g., benzene, toluene, xylenes) and hydrocarbons (propene, isoprene), oxygenated compounds (e.g., formaldehyde, acetaldehyde, acetone, methanol, C7 carbonyls), and three nitrogen-containing compounds (e.g., HCN, acetonitrile and acrylonitrile). Biogenic VOCs were minor components at this site. Propene was the most abundant lightweight hydrocarbon detected by this technique with concentrations up to 100+ nmol mol-1, and was highly correlated with its oxidation products, formaldehyde (up to ˜40 nmol mol-1) and acetaldehyde (up to ˜80 nmol/mol), with typical ratios close to 1 in propene-dominated plumes. In the case of aromatic species the high time resolution of the obtained data set helped in identifying different anthropogenic sources (e.g., industrial from urban emissions) and testing current emission inventories. A comparison with results from complimentary techniques (gas chromatography, differential optical absorption spectroscopy) was used to assess the selectivity of this on-line technique in a complex urban and industrial VOC matrix and give an interpretation of mass scans obtained by "soft" chemical ionization using proton-transfer via H3O+. The method was especially valuable in monitoring rapidly changing VOC plumes which passed over the site, and when coupled with meteorological data it was possible to identify likely sources.

  16. Perspective on Air Pollution: The Canadian Scene

    PubMed Central

    Shephard, R. J.

    1975-01-01

    Despite the large ratio of land mass to population, Canada has significant air pollution problems, some being due to our cold climate, the long arctic nights, and a mineral-based economy. Routes of intoxication include the respiration of polluted air and the secondary contamination of food and water. Although pollution is often measured in terms of industrial emissions, the physician must be concerned rather with the dose of pollutants to which the individual is exposed. The principal air pollutants, in terms of emitted tonnage, are carbon monoxide, sulfur dioxide, hydrocarbons, particulates, and oxides of nitrogen. Sources of these various materials are discussed. PMID:20469224

  17. Structure and Composition of Air-Plane Soots and Surrogates Analyzed by Raman Spectroscopy and Laser/Ions Desorption Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ortega, Ismael; Chazallon, Bertrand; Carpentier, Yvain; Irimiea, Cornelia; Focsa, Cristian; Ouf, François-Xavier; Salm, François; Delhaye, David; Gaffié, Daniel; Yon, Jérôme

    2015-04-01

    Aviation alters the composition of the atmosphere globally and can thus drive climate change and ozone depletion [1]. An aircraft exhaust plume contains species emitted by the engines, species formed in the plume from the emitted species and atmospheric species that become entrained into the plume. The majority of emitted species (gases and soot particles) are produced by the combustion of kerosene with ambient air in the combustion chamber of the engine. Emissions of soot particles by air-planes produce persistent contrails in the upper troposphere in ice-supersaturated air masses that contribute to cloudiness and impact the radiative properties of the atmosphere. These aerosol-cloud interactions represent one of the largest sources of uncertainty in global climate models [2]. Though the formation of atmospheric ice particles has been studied since many years [3], there are still numerous opened questions on nucleation properties of soot particles [4], as the ice nucleation experiments showed a large spread in results depending on the nucleation mode chosen and origin of the soot produced. Most likely one of the reasons behind these discrepancies resides in the different physico-chemical properties (composition, structure) of soot particles produced in different conditions, e.g. with respect to fuel or combustion techniques. In this work, we use Raman microscopy (266, 514 and 785 nm excitation) and ablation techniques (SIMS, Secondary Ions Mass Spectrometry, and Laser Desorption Mass Spectrometry) to characterize soot particles produced from air-plane at different engine regimes simulating a landing and taking-off (LTO) cycle. First, the spectral parameters of the first-order Raman band of various soot samples, collected from three different sources in the frame of the MERMOSE project (http://mermose.onera.fr/): PowerJet SaM-146 turbofan (four engine regimes), CAST generator (propane fuel, four different global equivalence ratios), and Kerosene laboratory flame

  18. Concentrations of Semivolatile Organic Compounds Associated with African Dust Air Masses in Mali, Cape Verde, Trinidad and Tobago, and the U.S. Virgin Islands, 2001-2008

    USGS Publications Warehouse

    Garrison, Virginia H.; Foreman, William T.; Genualdi, Susan A.; Majewski, Michael S.; Mohammed, Azad; Simonich, Staci Massey

    2011-01-01

    Every year, billions of tons of fine particles are eroded from the surface of the Sahara Desert and the Sahel of West Africa, lifted into the atmosphere by convective storms, and transported thousands of kilometers downwind. Most of the dust is carried west to the Americas and the Caribbean in the Saharan Air Layer (SAL). Dust air masses predominately impact northern South America during the Northern Hemisphere winter and the Caribbean and Southeastern United States in summer. Dust concentrations vary considerably temporally and spatially. In a dust source region (Mali), concentrations range from background levels of 575 micrograms per cubic meter (mu/u g per m3) to 13,000 mu/u g per m3 when visibility degrades to a few meters (Gillies and others, 1996). In the Caribbean, concentrations of 200 to 600 mu/u g per m3 in the mid-Atlantic and Barbados (Prospero and others, 1981; Talbot and others, 1986), 3 to 20 mu/u g per m3 in the Caribbean (Prospero and Nees, 1986; Perry and others, 1997); and >100 mu/u g per m3 in the Virgin Islands (this dataset) have been reported during African dust conditions. Mean dust particle size decreases as the SAL traverses from West Africa to the Caribbean and Americas as a result of gravitational settling. Mean particle size reaching the Caribbean is <1 micrometer (mu/u m) (Perry and others, 1997), and even finer particles are carried into Central America, the Southeastern United States, and maritime Canada. Particles less than 2.5 mu/u m diameter (termed PM2.5) can be inhaled deeply into human lungs. A large body of literature has shown that increased PM2.5 concentrations are linked to increased cardiovascular/respiratory morbidity and mortality (for example, Dockery and others, 1993; Penn and others, 2005).

  19. Determination of a wide range of volatile organic compounds in ambient air using multisorbent adsorption/thermal desorption and gas chromatography/mass spectrometry

    USGS Publications Warehouse

    Pankow, J.F.; Luo, W.; Isabelle, L.M.; Bender, D.A.; Baker, R.J.

    1998-01-01

    Adsorption/thermal desorption with multisorbent air-sampling cartridges was developed for the determination of 87 method analytes including halogenated alkanes, halogenated alkenes, ethers, alcohols, nitriles, esters, ketones, aromatics, a disulfide, and a furan. The volatilities of the compounds ranged from that of dichlorofluoromethane (CFC12) to that of 1,2,3- trichlorobenzene. The eight most volatile compounds were determined using a 1.5-L air sample and a sample cartridge containing 50 mg of Carbotrap B and 280 mg of Carboxen 1000; the remaining 79 compounds were determined using a 5-L air sample and a cartridge containing 180 mg of Carbotrap B and 70 mg of Carboxen 1000. Analysis and detection were by gas chromatography/mass spectrometry. The minimum detectable level (MDL) concentration values ranged from 0.01 parts per billion by volume (ppbv) for chlorobenzene to 0.4 ppbv for bromomethane; most of the MDL values were in the range 0.02-0.06 ppbv. No breakthrough was detected with the prescribed sample volumes. Analyte stability on the cartridges was very good. Excellent recoveries were obtained with independent check standards. Travel spike recoveries ranged from 90 to 110% for 72 of the 87 compounds. The recoveries were less than 70% for bromomethane and chloroethene and for a few compounds such as methyl acetate that are subject to losses by hydrolysis; the lowest travel spike recovery was obtained for bromomethane (62%). Blank values for all compounds were either below detection or very low. Ambient atmospheric sampling was conducted in New Jersey from April to December, 1997. Three sites characterized by low, moderate, and high densities of urbanization/traffic were sampled. The median detected concentrations of the compounds were either similar at all three sites (as with the chlorofluorocarbon compounds) or increased with the density of urbanization/traffic (as with dichloromethane, MTBE, benzene, and toluene). For toluene, the median detected

  20. Gamma Radiation Dose Rate in Air due to Terrestrial Radionuclides in Southern Brazil: Synthesis by Geological Units and Lithotypes Covered by the Serra do Mar Sul Aero-Geophysical Project

    SciTech Connect

    Bastos, Rodrigo O.; Appoloni, Carlos R.

    2008-08-07

    The absorbed dose rates in air due to terrestrial radionuclides were estimated from aerial gamma spectrometric data for an area of 48,600 km{sup 2} in Southern Brazil. The source data was the Serra do Mar Sul Aero-Geophysical Project back-calibrated in a cooperative work among the Geological Survey of Brazil, the Geological Survey of Canada, and Paterson, Grant and Watson Ltd. The concentrations of eU (ppm), eTh (ppm) and K (%) were converted to dose rates in air (nGy{center_dot}h{sup -1}) by accounting for the contribution of each element's concentration. Regional variation was interpreted according to lithotypes and a synthesis was performed according to the basic geological units present in the area. Higher values of total dose were estimated for felsic igneous and metamorphic rocks, with average values varying up to 119{+-}24 nGy{center_dot}h{sup -1}, obtained by Anitapolis syenite body. Sedimentary, metasedimentary and metamafic rocks presented the lower dose levels, and some beach deposits reached the lowest average total dose, 18.5{+-}8.2 nGy{center_dot}h{sup -1}. Thorium gives the main average contribution in all geological units, the highest value being reached by the nebulitic gneisses of Atuba Complex, 71{+-}23 nGy{center_dot}h{sup -1}. Potassium presents the lowest average contribution to dose rate in 53 of the 72 units analyzed, the highest contribution being obtained by intrusive alkaline bodies (28{+-}12 nGy{center_dot}h{sup -1}). The general pattern of geographic dose distribution respects well the hypotheses on geo-physicochemical behavior of radioactive elements.

  1. Present and future mass standards for the LNE watt balance and the future dissemination of the mass unit in France

    NASA Astrophysics Data System (ADS)

    Pinot, Patrick; Beaudoux, Florian; Bentouati, Djilali; Espel, Patrick; Madec, Tanguy; Thomas, Matthieu; Silvestri, Zaccari; Ziane, Djamel; Piquemal, François

    2016-08-01

    The value of the Planck constant h was determined in 2014 by means of the LNE watt balance experiment. The relative standard uncertainty was 31 parts in 108. This first determination was performed in air with a 500 g mass standard made from XSH Alacrite. The main uncertainty components in air associated with the mass involve the calibration, the mass stability, the buoyancy correction and the magnetic interaction correction. The combined relative uncertainty due to the mass is 7.2 parts in 108. The use in 2016 of a mass standard made from platinum iridium alloy significantly reduces the component of uncertainty arising from the mass standard for a Planck constant measurement either in air or under vacuum. The relative uncertainty due to this contribution is estimated to be about 3 parts in 108 in air and one part in 108 under vacuum. The future system for the dissemination of the mass unit using the LNE watt balance will be based on a primary realization with three 500 g mass standards made from platinum–iridium alloy, pure iridium and Udimet 720 respectively, coupled with a pool of kilograms made from different materials. Pure iridium and Udimet 720 are new materials to make reference mass standards proposed by CNAM and LNE respectively and have never been used by any NMI for manufacturing mass standards until now. Some new results concerning their surface behavior are given.

  2. Air leakage in residential solar heating systems

    NASA Astrophysics Data System (ADS)

    Shingleton, J. G.; Cassel, D. E.; Overton, R. L.

    1981-02-01

    A series of computer simulations was performed to evaluate the effects of component air leakage on system thermal performance for a typical residential solar heating system, located in Madison, Wisconsin. Auxiliary energy required to supplement solar energy for space heating was determined using the TRNSYS computer program, for a range of air leakage rates at the solar collector and pebble bed storage unit. The effects of heat transfer and mass transfer between the solar equipment room and the heated building were investigated. The effect of reduced air infiltration into the building due to pressurized by the solar air heating system were determined. A simple method of estimating the effect of collector array air leakage on system thermal performance was evaluated, using the f CHART method.

  3. High-Compression-Ratio; Atkinson-Cycle Engine Using Low-Pressure Direct Injection and Pneumatic-Electronic Valve Actuation Enabled by Ionization Current and Foward-Backward Mass Air Flow Sensor Feedback

    SciTech Connect

    Harold Schock; Farhad Jaberi; Ahmed Naguib; Guoming Zhu; David Hung

    2007-12-31

    This report describes the work completed over a two and one half year effort sponsored by the US Department of Energy. The goal was to demonstrate the technology needed to produce a highly efficient engine enabled by several technologies which were to be developed in the course of the work. The technologies included: (1) A low-pressure direct injection system; (2) A mass air flow sensor which would measure the net airflow into the engine on a per cycle basis; (3) A feedback control system enabled by measuring ionization current signals from the spark plug gap; and (4) An infinitely variable cam actuation system based on a pneumatic-hydraulic valve actuation These developments were supplemented by the use of advanced large eddy simulations as well as evaluations of fuel air mixing using the KIVA and WAVE models. The simulations were accompanied by experimental verification when possible. In this effort a solid base has been established for continued development of the advanced engine concepts originally proposed. Due to problems with the valve actuation system a complete demonstration of the engine concept originally proposed was not possible. Some of the highlights that were accomplished during this effort are: (1) A forward-backward mass air flow sensor has been developed and a patent application for the device has been submitted. We are optimistic that this technology will have a particular application in variable valve timing direct injection systems for IC engines. (2) The biggest effort on this project has involved the development of the pneumatic-hydraulic valve actuation system. This system was originally purchased from Cargine, a Swedish supplier and is in the development stage. To date we have not been able to use the actuators to control the exhaust valves, although the actuators have been successfully employed to control the intake valves. The reason for this is the additional complication associated with variable back pressure on the exhaust valves when

  4. The effect of air leakage and heat exchange on the decay of entrapped air pocket slamming oscillations

    NASA Astrophysics Data System (ADS)

    Abrahamsen, Bjørn C.; Faltinsen, Odd M.

    2011-10-01

    The phenomenon studied in this work is that of an air pocket entrapped by a free surface water wave inside a rectangular tank at a high filling level. The wave, which is a gravity wave, is caused by forced horizontal motion which is constructed in a particular way, in order to entrap an air pocket as it approaches the upper left corner of the tank. As the wave touches the roof, the air is compressed and starts to oscillate. The oscillations resemble, to some extent, the free oscillations of an underdamped mass-spring system, where the mass is related to the generalized added mass effect of the water pressure associated with the air pocket oscillations. The stiffness is due to the compressibility of the air. The reason for the damping or, more generally, the decay of the air pocket oscillations is less understood. Air leakage has been proposed as one possible reason for this decay. In this work, the role of air leakage is found not to be the reason for the decay of the air pocket oscillations, because it is not present during major parts of the impact. However, by drilling holes in the roof of the tank, the effect of leakage during the oscillations is proven to cause decay. To explain the physical source of the decay of the oscillations, damping due to heat transfer to and from the air pocket is investigated through an analytical one-dimensional steady-state model. The damping due to heat transfer is observed to play an important role. The obtained understanding of the mechanisms causing the decay of the air-pocket impact at the upper corner is believed to be relevant to other types of impacts, particularly the entrapment of air pockets on walls by breaking waves.

  5. Degradation characteristics of air cathode in zinc air fuel cells

    NASA Astrophysics Data System (ADS)

    Ma, Ze; Pei, Pucheng; Wang, Keliang; Wang, Xizhong; Xu, Huachi; Liu, Yongfeng; peng, Guanlin

    2015-01-01

    The zinc air fuel cell (ZAFC) is a promising candidate for electrical energy storage and electric vehicle propulsion. However, its limited durability has become a major obstacle for its successful commercialization. In this study, 2-cell stacks, 25 cm² cells and three-electrode half-cells are constructed to experimentally investigate the degradation characteristics of the air cathode. The results of electrochemical tests reveal that the peak power density for the 25 cm2 cell with a new air cathode is 454 mW cm-2, which is twice as the value of the used air cathode. The electrochemical impedance analysis shows that both the charge transfer resistance and the mass transfer resistance of the used air cathodes have increased, suggesting that the catalyst surface area and gas diffusion coefficient have decreased significantly. Additionally, the microstructure and morphology of the catalytic layer (CL) and gas diffusion layer (GDL) are characterized by scanning electron microscopes (SEM). SEM results confirm that the micropores in CL and GDL of the used air cathode are seriously clogged, and many catalyst particles are lost. Therefore, the performance degradation is mainly due to the clogging of micropores and loss of catalyst particles. Furthermore, hypotheses of degradation mechanism and mitigation strategies for GDL and CL are discussed briefly.

  6. Potential for post-closure radionuclide redistribution due to biotic intrusion: aboveground biomass, litter production rates, and the distribution of root mass with depth at material disposal area G, Los Alamos National Laboratory

    SciTech Connect

    French, Sean B; Christensen, Candace; Jennings, Terry L; Jaros, Christopher L; Wykoff, David S; Crowell, Kelly J; Shuman, Rob

    2008-01-01

    Low-level radioactive waste (LLW) generated at the Los Alamos National Laboratories (LANL) is disposed of at LANL's Technical Area (T A) 54, Material Disposal Area (MDA) G. The ability of MDA G to safely contain radioactive waste during current and post-closure operations is evaluated as part of the facility's ongoing performance assessment (PA) and composite analysis (CA). Due to the potential for uptake and incorporation of radio nuclides into aboveground plant material, the PA and CA project that plant roots penetrating into buried waste may lead to releases of radionuclides into the accessible environment. The potential amount ofcontamination deposited on the ground surface due to plant intrusion into buried waste is a function of the quantity of litter generated by plants, as well as radionuclide concentrations within the litter. Radionuclide concentrations in plant litter is dependent on the distribution of root mass with depth and the efficiency with which radionuclides are extracted from contaminated soils by the plant's roots. In order to reduce uncertainties associated with the PA and CA for MDA G, surveys are being conducted to assess aboveground biomass, plant litter production rates, and root mass with depth for the four prominent vegetation types (grasses, forbs, shrubs and trees). The collection of aboveground biomass for grasses and forbs began in 2007. Additional sampling was conducted in October 2008 to measure root mass with depth and to collect additional aboveground biomass data for the types of grasses, forbs, shrubs, and trees that may become established at MDA G after the facility undergoes final closure, Biomass data will be used to estimate the future potential mass of contaminated plant litter fall, which could act as a latent conduit for radionuclide transport from the closed disposal area. Data collected are expected to reduce uncertainties associated with the PA and CA for MDA G and ultimately aid in the assessment and subsequent

  7. Interlaboratory evaluation of a standardized inductively coupled plasma mass spectrometry method for the determination of trace beryllium in air filter samples.

    PubMed

    Ashley, Kevin; Brisson, Michael J; Howe, Alan M; Bartley, David L

    2009-12-01

    A collaborative interlaboratory evaluation of a newly standardized inductively coupled plasma mass spectrometry (ICP-MS) method for determining trace beryllium in workplace air samples was carried out toward fulfillment of method validation requirements for ASTM International voluntary consensus standard test methods. The interlaboratory study (ILS) was performed in accordance with an applicable ASTM International standard practice, ASTM E691, which describes statistical procedures for investigating interlaboratory precision. Uncertainty was also estimated in accordance with ASTM D7440, which applies the International Organization for Standardization Guide to the Expression of Uncertainty in Measurement to air quality measurements. Performance evaluation materials (PEMs) used consisted of 37 mm diameter mixed cellulose ester filters that were spiked with beryllium at levels of 0.025 (low loading), 0.5 (medium loading), and 10 (high loading) microg Be/filter; these spiked filters were prepared by a contract laboratory. Participating laboratories were recruited from a pool of over 50 invitees; ultimately, 20 laboratories from Europe, North America, and Asia submitted ILS results. Triplicates of each PEM (blanks plus the three different loading levels) were conveyed to each volunteer laboratory, along with a copy of the draft standard test method that each participant was asked to follow; spiking levels were unknown to the participants. The laboratories were requested to prepare the PEMs by one of three sample preparation procedures (hotplate or microwave digestion or hotblock extraction) that were described in the draft standard. Participants were then asked to analyze aliquots of the prepared samples by ICP-MS and to report their data in units of mu g Be/filter sample. Interlaboratory precision estimates from participating laboratories, computed in accordance with ASTM E691, were 0.165, 0.108, and 0.151 (relative standard deviation) for the PEMs spiked at 0.025, 0

  8. Sensitive monitoring of volatile chemical warfare agents in air by atmospheric pressure chemical ionization mass spectrometry with counter-flow introduction.

    PubMed

    Seto, Yasuo; Kanamori-Kataoka, Mieko; Tsuge, Koichiro; Ohsawa, Isaac; Iura, Kazumitsu; Itoi, Teruo; Sekiguchi, Hiroyuki; Matsushita, Koji; Yamashiro, Shigeharu; Sano, Yasuhiro; Sekiguchi, Hiroshi; Maruko, Hisashi; Takayama, Yasuo; Sekioka, Ryoji; Okumura, Akihiko; Takada, Yasuaki; Nagano, Hisashi; Waki, Izumi; Ezawa, Naoya; Tanimoto, Hiroyuki; Honjo, Shigeru; Fukano, Masumi; Okada, Hidehiro

    2013-03-01

    A new method for sensitively and selectively detecting chemical warfare agents (CWAs) in air was developed using counter-flow introduction atmospheric pressure chemical ionization mass spectrometry (MS). Four volatile and highly toxic CWAs were examined, including the nerve gases sarin and tabun, and the blister agents mustard gas (HD) and Lewisite 1 (L1). Soft ionization was performed using corona discharge to form reactant ions, and the ions were sent in the direction opposite to the airflow by an electric field to eliminate the interfering neutral molecules such as ozone and nitrogen oxide. This resulted in efficient ionization of the target CWAs, especially in the negative ionization mode. Quadrupole MS (QMS) and ion trap tandem MS (ITMS) instruments were developed and investigated, which were movable on the building floor. For sarin, tabun, and HD, the protonated molecular ions and their fragment ions were observed in the positive ion mode. For L1, the chloride adduct ions of L1 hydrolysis products were observed in negative ion mode. The limit of detection (LOD) values in real-time or for a 1 s measurement monitoring the characteristic ions were between 1 and 8 μg/m(3) in QMS instrument. Collision-induced fragmentation patterns for the CWAs were observed in an ITMS instrument, and optimized combinations of the parent and daughter ion pairs were selected to achieve real-time detection with LOD values of around 1 μg/m(3). This is a first demonstration of sensitive and specific real-time detection of both positively and negatively ionizable CWAs by MS instruments used for field monitoring. PMID:23339735

  9. Chemical composition of tropospheric air masses encountered during high altitude flights (>11.5 km) during the 2009 fall Operation Ice Bridge field campaign

    NASA Astrophysics Data System (ADS)

    Yang, Mei Ying Melissa; Vay, Stephanie A.; Stohl, Andreas; Choi, Yonghoon; Diskin, Glenn S.; Sachse, Glen W.; Blake, Donald R.

    2012-09-01

    As part of the 2009 Operation Ice Bridge campaign, the NASA DC-8 aircraft was used to fill the data-time gap in laser observation of the changes in ice sheets, glaciers and sea ice between ICESat-I (Ice, Cloud, and land Elevation Satellite) and ICESat-II. Complementing the cryospheric instrument payload were four in situ atmospheric sampling instruments integrated onboard to measure trace gas concentrations of CO2, CO, N2O, CH4, water vapor and various VOCs (Volatile Organic Compounds). This paper examines two plumes encountered at high altitude (12 km) during the campaign; one during a southbound transit flight (13°S) and the other at 86°S over Antarctica. The data presented are especially significant as the Southern Hemisphere is heavily under-sampled during the austral spring, with few if any high-resolution airborne observations of atmospheric gases made over Antarctica. Strong enhancements of CO, CH4, N2O, CHCl3, OCS, C2H6, C2H2 and C3H8 were observed in the two intercepted air masses that exhibited variations in VOC composition suggesting different sources. The transport model FLEXPART showed that the 13°S plume contained predominately biomass burning emissions originating from Southeast Asia and South Africa, while both anthropogenic and biomass burning emissions were observed at 86°S with South America and South Africa as indicated source regions. The data presented here show evidence that boundary layer pollution is transported from lower latitudes toward the upper troposphere above the South Pole, which may not have been observed in the past.

  10. Determination of 43 polycyclic aromatic hydrocarbons in air particulate matter by use of direct elution and isotope dilution gas chromatography/mass spectrometry.

    PubMed

    Li, Zheng; Pittman, Erin N; Trinidad, Debra A; Romanoff, Lovisa C; Mulholland, James; Sjödin, Andreas

    2010-02-01

    We are reporting a method for measuring 43 polycyclic aromatic hydrocarbons (PAH) and their methylated derivatives (Me-PAHs) in air particulate matter (PM) samples using isotope dilution gas chromatography/high-resolution mass spectrometry (GC/HRMS). In this method, PM samples were spiked with internal standards, loaded into solid phase extraction cartridges, and eluted by dichloromethane. The extracts were concentrated, spiked with a recovery standard, and analyzed by GC/HRMS at 10,000 resolution. Sixteen (13)C-labeled PAHs and two deuterated Me-PAHs were used as internal standards to account for instrument variability and losses during sample preparation. Recovery of labeled internal standards was in the range of 86-115%. The proposed method is less time-consuming than commonly used extraction methods, such as sonication and accelerated solvent extraction (ASE), and it eliminates the need for a filtration step required after the sonication extraction method. Limits of detection ranged from 41 to 332 pg/sample for the 43 analytes. This method was used to analyze reference materials from the National Institute of Standards and Technology. The results were consistent with those from ASE and sonication extraction, and these results were also in good agreement with the certified or reference concentrations. The proposed method was then used to measure PAHs on PM(2.5) samples collected at three sites (urban, suburban, and rural) in Atlanta, GA. The results showed distinct seasonal and spatial variation and were consistent with an earlier study measuring PM(2.5) samples using an ASE method, further demonstrating the compatibility of this method and the commonly used ASE method. PMID:19936717

  11. Remediation of Chlorinated Solvent Plumes Using In-Situ Air Sparging—A 2-D Laboratory Study

    PubMed Central

    Adams, Jeffrey A.; Reddy, Krishna R.; Tekola, Lue

    2011-01-01

    In-situ air sparging has evolved as an innovative technique for soil and groundwater remediation impacted with volatile organic compounds (VOCs), including chlorinated solvents. These may exist as non-aqueous phase liquid (NAPL) or dissolved in groundwater. This study assessed: (1) how air injection rate affects the mass removal of dissolved phase contamination, (2) the effect of induced groundwater flow on mass removal and air distribution during air injection, and (3) the effect of initial contaminant concentration on mass removal. Dissolved-phase chlorinated solvents can be effectively removed through the use of air sparging; however, rapid initial rates of contaminant removal are followed by a protracted period of lower removal rates, or a tailing effect. As the air flow rate increases, the rate of contaminant removal also increases, especially during the initial stages of air injection. Increased air injection rates will increase the density of air channel formation, resulting in a larger interfacial mass transfer area through which the dissolved contaminant can partition into the vapor phase. In cases of groundwater flow, increased rates of air injection lessened observed downward contaminant migration effect. The air channel network and increased air saturation reduced relative hydraulic conductivity, resulting in reduced groundwater flow and subsequent downgradient contaminant migration. Finally, when a higher initial TCE concentration was present, a slightly higher mass removal rate was observed due to higher volatilization-induced concentration gradients and subsequent diffusive flux. Once concentrations are reduced, a similar tailing effect occurs. PMID:21776228

  12. The method for on-site determination of trace concentrations of methyl mercaptan and dimethyl sulfide in air using a mobile mass spectrometer with atmospheric pressure chemical ionization, combined with a fast enrichment/separation system.

    PubMed

    Kudryavtsev, Andrey S; Makas, Alexey L; Troshkov, Mikhail L; Grachev, Mikhail А; Pod'yachev, Sergey P

    2014-06-01

    A method for fast simultaneous on-site determination of methyl mercaptan and dimethyl sulfide in air was developed. The target compounds were actively collected on silica gel, followed by direct flash thermal desorption, fast separation on a short chromatographic column and detection by means of mass spectrometer with atmospheric pressure chemical ionization. During the sampling of ambient air, water vapor was removed with a Nafion selective membrane. A compact mass spectrometer prototype, which was designed earlier at Trofimuk Institute of Petroleum Geology and Geophysics, was used. The minimization of gas load of the atmospheric pressure ion source allowed reducing the power requirements and size of the vacuum system and increasing its ruggedness. The measurement cycle is about 3 min. Detection limits in a 0.6 L sample are 1 ppb for methyl mercaptan and 0.2 ppb for dimethyl sulfide. PMID:24725876

  13. Portable Time of Flight-mass Spec and Animal Feeding Operations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agriculture air quality studies monitoring emissions of volatile organic compounds (VOCs) from animal production facilities present unique challenges due to the air matrix and concentration levels of target compounds. Recent developments in the cost and capacity of field portable mass spectrometers...

  14. Experimental Studies on High Speed Air Intakes

    NASA Astrophysics Data System (ADS)

    Panigrahy, Amit Kumar; Muruganandam, T. M.

    All high speed air breathing engines require an inlet to decelerate air from free stream velocity to a lower velocity conducive to combustion. The inlet is designed to capture and deliver the required mass flow to combustion chamber with minimum pressure loss, along with minimum flow distortion. Inlet buzz can occur due to several reasons, such as large internal area contraction ratio, serious shock-boundary layer interactions, and high back pressure. Inlet buzz is detrimental to thrust and can even cause structural damage. Thus a detailed back pressure and over contraction based study of inlet behavior is needed.

  15. Eggplant-derived microporous carbon sheets: towards mass production of efficient bifunctional oxygen electrocatalysts at low cost for rechargeable Zn-air batteries.

    PubMed

    Li, Bing; Geng, Dongsheng; Lee, Xinjing Shannon; Ge, Xiaoming; Chai, Jianwei; Wang, Zhijuan; Zhang, Jie; Liu, Zhaolin; Hor, T S Andy; Zong, Yun

    2015-05-25

    We report 2D microporous carbon sheets with high surface area, derived from eggplant via simple carbonization and KOH activation, as low cost yet efficient bifunctional catalysts for high performance rechargeable zinc-air batteries. PMID:25920952

  16. EPA method to-15 VOCs in air collected in SUMMA (trade name) canisters and analyzed by gas chromatography/mass spectrometry. Final report

    SciTech Connect

    McClenny, W.A.; Oliver, K.D.; Adams, J.R.

    1996-04-18

    Method TO-15 is an addition to the EPA Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air and consists of guidance for the sampling and analysis of volatile organic compounds (VOCs) in air. The method has undergone an initial review by the EPA and has been placed on the AMTIC bulletin board maintained by EPA`s Office of Air Quality Planning and Standards (OAQPS) for further comments before final review and formal acceptance as a new method. The method is a companion method to the previously published TO-14 method entitled, `Determination of Volatile Organic Compounds (VOCs) in Ambient Air Using SUMMA(TM) Polished Canister Sampling and Gas Chromatographic (GC) Analysis`. TO-15 differs from TO-14 in the following ways: (1) the water management system consists of the use of a small sample volume or a multisorbent/dry purge technique or both to dry the air sample; (2) the more extensive set of compounds given in Title III of the Clean Air Act Amemdments (CAAA) of 1990 constitutes the target list; (3) GC/MS techniques are recommended as the only means to identify and quantify target compounds; (4) method performance criteria are specified for acceptance of data, thereby allowing the use of alternate but equivalent sampling and analytical instrumentation; and (5) enhanced provisions for quality control are included.

  17. Vertical variation of optical properties of mixed Asian dust/pollution plumes according to pathway of air mass transport over East Asia

    NASA Astrophysics Data System (ADS)

    Shin, S.-K.; Müller, D.; Lee, C.; Lee, K. H.; Shin, D.; Kim, Y. J.; Noh, Y. M.

    2015-06-01

    We use five years (2009-2013) of multiwavelength Raman lidar measurements at Gwangju, South Korea (35.10° N, 126.53° E) for the identification of changes of optical properties of East Asian dust depending on its transport path over China. Profiles of backscatter and extinction coefficients, lidar ratios, and backscatter-related Ångström exponents (wavelength pair 355/532 nm) were measured at Gwangju. Linear particle depolarization ratios were used to identify East Asian dust layers. We used backward trajectory modeling to identify the pathway and the vertical position of dust-laden air masses over China during long-range transport. Most cases of Asian dust events can be described by the emission of dust in desert areas and subsequent transport over highly polluted regions of China. The Asian dust plumes could be categorized into two classes according to the height above ground at which these plumes were transported: (case I) the dust layers passed over China at high altitude levels (> 3 km) until arrival over Gwangju, and (case II) the Asian dust layers were transported near the surface and within the lower troposphere (< 3 km) over industrialized areas before they arrived over Gwangju. We find that the optical characteristics of these mixed Asian dust layers over Gwangju differ depending on their vertical position above ground over China and the change of height above ground during transport. The mean linear particle depolarization ratio was 0.21 ± 0.06 (at 532 nm), the mean lidar ratios were 52 ± 7 sr at 355 nm and 53 ± 8 sr at 532 nm, and the mean Ångström exponent was 0.74 ± 0.31 for case I. In contrast, plumes transported at lower altitudes (case II) showed low depolarization ratios (0.13 ± 0.04 at 532 nm), and higher lidar ratio (63 ± 9 sr at 355 nm and 62 ± 8 sr at 532 nm) and Ångström exponents (0.98 ± 0.51). These numbers show that the optical characteristics of mixed Asian plumes are more similar to optical characteristics of urban

  18. Elbow mass flow meter

    DOEpatents

    McFarland, Andrew R.; Rodgers, John C.; Ortiz, Carlos A.; Nelson, David C.

    1994-01-01

    Elbow mass flow meter. The present invention includes a combination of an elbow pressure drop generator and a shunt-type mass flow sensor for providing an output which gives the mass flow rate of a gas that is nearly independent of the density of the gas. For air, the output is also approximately independent of humidity.

  19. Monitoring Air Pollution In and Around the Premises of Industrial Parks Using Two Types of Electronic Nose and Gas Chromatography-Ion Trap Mass Spectrometry

    SciTech Connect

    Liu, Jen Yu; Ling, Yong Chien, Sr.

    2004-03-31

    Two types of electronic nose and GC-MS were used to monitor air pollution in the premises of seven industrial parks. Real-time analysis of air at the sites was performed using portable electronic noses. Air samples were analyzed from the up and down stream direction along the wind flow to investigate the effect or distribution of the pollutants on the surrounding environment. The advantage of multisensors in spatially resolved sensing for direct multicomponent analysis was explored to minimize tedious sample preparation procedure. Electronic nose could give characteristic odor fingerprints, which were correlated with the pollutants analyzed using GC-MS providing detailed diagnostic information such as the presence of hydrocarbons, halocarbons, phenols, nitrogenous benzenes, sulfur compounds, lipid-derived compounds, polysiloxanes, etc. Subsequent principal component analysis helped in identifying the source of pollutants. The applicability of the electronic nose was demonstrated confirming it to be a simple and rapid screening method for identifying the pollutant source.

  20. The lower vitamin C plasma concentrations in elderly men compared with elderly women can partly be attributed to a volumetric dilution effect due to differences in fat-free mass.

    PubMed

    Jungert, Alexandra; Neuhäuser-Berthold, Monika

    2015-03-14

    Women show higher vitamin C plasma concentrations than men, but the reasons for this observation still require elucidation. The objective of the present study was to investigate whether sex differences in vitamin C plasma concentrations are present in elderly subjects and whether these differences are due to sex-specific lifestyles, total antioxidant status (TAOS) and/or body composition. Fasting plasma concentrations of vitamin C were assessed by photometric detection in a cross-sectional study of 181 women and eighty-nine men aged 62-92 years. Body composition was determined by bioelectrical impedance analysis. Vitamin C intake was assessed with a 3 d estimated dietary record. Stepwise multiple regression analyses were performed to investigate whether sex is an independent predictor of vitamin C plasma concentrations by controlling for age, vitamin C intake, lifestyle factors, TAOS and body composition. Women showed higher vitamin C plasma concentrations than men (76 v. 62 μmol/l, P< 0·0001). In the multiple regression analysis, male sex was a negative predictor of vitamin C plasma concentrations (β = -0·214), as long as absolute fat-free mass (FFM) was not considered as a confounder. When absolute FFM was included, sex was no longer a predictor of vitamin C plasma concentrations, whereas absolute FFM (β = -0·216), physical activity level (β = 0·165), intake of vitamin C supplements (β = 0·164), age (β = 0·147) and smoking (β = -0·125) affected vitamin C plasma concentrations. The results indicate that a higher absolute FFM, and thus a higher distribution volume of vitamin C, contributes to lower vitamin C plasma concentrations in men than women. PMID:25735881

  1. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, dust, ... a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  2. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  3. SOURCE APPORTIONMENT OF AIR POLLUTION IN CHINA: EXTENDING THE USEFULNESS OF RECEPTOR MODELING BY COMBINING MULTIVARIATE AND CHEMICAL MASS BALANCE MODELS

    EPA Science Inventory

    This research explores the possibility of using a two step method of identify and quantify air pollution emissions in an urban environment. he procedure was a mathematical model called Target Transformation Factor Analysis (TTFA) to estimate source profiles using ambient trace el...

  4. Flame Propagation of Butanol Isomers/Air Mixtures

    SciTech Connect

    Veloo, Peter S.; Egolfopoulos, Fokion N.

    2011-01-01

    An experimental and computational study was conducted on the propagation of flames of saturated butanol isomers. The experiments were performed in the counterflow configuration under atmospheric pressure, unburned mixture temperature of 343 K, and for a wide range of equivalence ratios. The experiments were simulated using a recent kinetic model for the four isomers of butanol. Results indicate that n-butanol/air flames propagate somewhat faster than both sec-butanol/air and iso-butanol/air flames, and that tert-butanol/air flames propagate notably slower compared to the other three isomers. Reaction path analysis of tert-butanol/air flames revealed that iso-butene is a major intermediate, which subsequently reacts to form the resonantly stable iso-butenyl radical retarding thus the overall reactivity of tert-butanol/air flames relatively to the other three isomers. Through sensitivity analysis, it was determined that the mass burning rates of sec-butanol/air and iso-butanol/air flames are sensitive largely to hydrogen, carbon monoxide, and C{sub 1}–C{sub 2} hydrocarbon kinetics and not to fuel-specific reactions similarly to n-butanol/air flames. However, for tert-butanol/air flames notable sensitivity to fuel-specific reactions exists. While the numerical results predicted closely the experimental data for n-butanol/air and sec-butanol/air flames, they overpredicted and underpredicted the laminar flame speeds for iso-butanol/air and tert-butanol/air flames respectively. It was demonstrated further that the underprediction of the laminar flame speeds of tert-butanol/air flames by the model was most likely due to deficiencies of the C{sub 4}-alkene kinetics.

  5. Mass composition of 10{sup 17}- to 10{sup 18}-eV primary cosmic rays according to data on the lateral distribution of radio emission from extensive air showers

    SciTech Connect

    Kalmykov, N. N. Konstantinov, A. A.; Vedeneev, O. V.

    2012-12-15

    Experimental data obtained for the lateral distribution of radio emission from extensive air showers (EAS) at the array of Moscow State University (30-34 MHz) and the LOPES array (40-80 MHz) were comparedwith the results of calculations performed within amicroscopic approach based on aMonte Carlo simulation of EAS (CORSIKA code). The same experimental data were used to reconstruct the distribution of the depth of the EAS maximum at cosmic-ray energies in the range of 1017-1018 eV. The energy dependence of the depth of the EAS maximum was constructed for the case of data from the LOPES array, and the mass composition of cosmic rays was estimated for this case. From the resulting dependences, it follows that the mass composition shows a trend toward becoming lighter in the energy range being considered.

  6. Drop size distribution and air velocity measurements in air assist swirl atomizer sprays

    NASA Astrophysics Data System (ADS)

    Mao, C.-P.; Oechsle, V.; Chigier, N.

    1987-03-01

    Detailed measurements of mean drop size (SMD) and size distribution parameters have been made using a Fraunhofer diffraction particle sizing instrument in a series of sprays generated by an air assist swirl atomizer. Thirty-six different combinations of fuel and air mass flow rates were examined with liquid flow rates up to 14 lbm/hr and atomizing air flow rates up to 10 lbm/hr. Linear relationships were found between SMD and liquid to air mass flow rate ratios. SMD increased with distance downstream along the center line and also with radial distance from the axis. Increase in obscuration with distance downstream was due to an increase in number density of particles as the result of deceleration of drops and an increase in the exposed path length of the laser beam. Velocity components of the atomizing air flow field measured by a laser anemometer show swirling jet air flow fields with solid body rotation in the core and free vortex flow in the outer regions.

  7. Drop size distribution and air velocity measurements in air assist swirl atomizer sprays

    NASA Technical Reports Server (NTRS)

    Mao, C.-P.; Oechsle, V.; Chigier, N.

    1987-01-01

    Detailed measurements of mean drop size (SMD) and size distribution parameters have been made using a Fraunhofer diffraction particle sizing instrument in a series of sprays generated by an air assist swirl atomizer. Thirty-six different combinations of fuel and air mass flow rates were examined with liquid flow rates up to 14 lbm/hr and atomizing air flow rates up to 10 lbm/hr. Linear relationships were found between SMD and liquid to air mass flow rate ratios. SMD increased with distance downstream along the center line and also with radial distance from the axis. Increase in obscuration with distance downstream was due to an increase in number density of particles as the result of deceleration of drops and an increase in the exposed path length of the laser beam. Velocity components of the atomizing air flow field measured by a laser anemom