WorldWideScience

Sample records for background particle concentrations

  1. Urban background levels of particle number concentration and sources in Vilnius, Lithuania

    Science.gov (United States)

    Byčenkienė, Steigvilė; Plauškaitė, Kristina; Dudoitis, Vadimas; Ulevicius, Vidmantas

    2014-06-01

    This study presents results of research on urban aerosol particles with a focus on the aerosol particle number concentration (PNC) and the particle size distribution. The real time measurements of aerosol PNC (> 4.5 nm) and number size distributions (9-840 nm) were performed. The seasonal variations essentially comprised the minimum monthly mean in October 2010 (3400 ± 3000 cm- 3) and the maximum in April 2011 (19,000 ± 15,000 cm- 3). The mean annual PNC was 10,000 ± 8000 cm- 3 with an average mode size of 30-50 nm. The presence of strong diurnal patterns in aerosol PNC was evident as a direct effect of three sources of aerosol particles (nucleation, traffic, and residential heating). Hybrid receptor modeling potential source contribution function (PSCF) and concentration weighted trajectory (CWT) were used by incorporating 72-h backward trajectories and measurements of PNC in Vilnius. The results of trajectory clustering and the PSCF method demonstrated that possible additional source areas contributing to the elevated particle number concentration in Vilnius could be industrial areas in central Europe. Principal component analysis (PCA) revealed highest loadings for PNC, PM10, NOx, NO, NO2 and SO2 concentrations, indicating combustion processes occurring in vehicle engines and use of sulfur-containing fossil fuels for residential heating.

  2. European Marine Background Ice Nucleating Particle concentrations Measured at the Mace Head Station, Ireland.

    Science.gov (United States)

    Atkinson, James; Kanji, Zamin A.; Ovadnevaite, Jurgita; Ceburnis, Darius; O'Dowd, Colin

    2016-04-01

    Ice formation is an important process which controls cloud microphysical properties and can be critical in the creation of precipitation, therefore influencing the hydrological cycle and energy budget of the Earth. Ice Nucleating Particles (INP) can greatly increase the temperature and rate of ice formation, but the sources and geographical distributions of these particles is not well understood. Mace Head in Ireland is a coastal site on the north eastern edge of Europe with prevailing winds generally from the Atlantic Ocean with little continental influence. Observations of INP concentration from August 2015 using the Horizontal Ice Nucleation Chamber (HINC) at temperature of -30 C are presented. Correlations between the INP and meteorological conditions and aerosol compositions are made, as well as comparisons with commonly used INP concentration parameterisations. Observed INP concentrations are generally low, suggesting that oceanic sources in this region do not contribute significant numbers of INP to the global distribution.

  3. Physical properties and concentration of aerosol particles over the Amazon tropical forest during background and biomass burning conditions

    Directory of Open Access Journals (Sweden)

    P. Guyon

    2003-01-01

    Full Text Available We investigated the size distribution, scattering and absorption properties of Amazonian aerosols and the optical thickness of the aerosol layer under the pristine background conditions typical of the wet season, as well as during the biomass-burning-influenced dry season. The measurements were made during two campaigns in 1999 as part of the European contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA-EUSTACH. In moving from the wet to the dry season, median particle numbers were observed to increase from values comparable to those of the remote marine boundary layer (~400 cm-3 to values more commonly associated with urban smog (~4000 cm-3, due to a massive injection of submicron smoke particles. Aerosol optical depths at 500 nm increased from 0.05 to 0.8 on average, reaching a value of 2 during the dry season. Scattering and absorption coefficients, measured at 550 nm, showed a concomitant increase from average values of 6.8 and 0.4 Mm-1 to values of 91 and 10 Mm-1, respectively, corresponding to an estimated decrease in single-scattering albedo from ca. 0.97 to 0.91. The roughly tenfold increase in many of the measured parameters attests to the dramatic effect that extensive seasonal biomass burning (deforestation, pasture cleaning is having on the composition and properties of aerosols over Amazonia. The potential exists for these changes to impact on regional and global climate through changes to the extinction of solar radiation as well as the alteration of cloud properties.

  4. Source apportionment of fine PM and sub-micron particle number concentrations at a regional background site in the western Mediterranean: a 2.5 year study

    Science.gov (United States)

    Cusack, M.; Pérez, N.; Pey, J.; Alastuey, A.; Querol, X.

    2013-05-01

    The chemical composition and sources of ambient fine particulate matter (PM1) over a period of 2.5 years for a regional background site in the western Mediterranean are presented in this work. Furthermore, sub-micron particle number concentrations and the sources of these particles are also presented. The mean PM1 concentration for the measurement period was 8.9 μg m-3, with organic matter (OM) and sulphate comprising most of the mass (3.2 and 1.5 μg m-3 respectively). Six sources were identified in PM1 by Positive Matrix Factorisation (PMF): secondary organic aerosol, secondary nitrate, industrial, traffic + biomass burning, fuel oil combustion and secondary sulphate. Typically anthropogenic sources displayed elevated concentrations during the week with reductions at weekends. Nitrate levels were elevated in winter and negligible in summer, whereas secondary sulphate levels underwent a contrasting seasonal evolution with highest concentrations in summer, similar to the fuel oil combustion source. The SOA source was influenced by episodes of sustained pollution as a result of anticyclonic conditions occurring during winter, giving rise to thermal inversions and the accumulation of pollutants in the mixing layer. Increased levels in summer were owing to higher biogenic emissions and regional recirculation of air masses. The industrial source decreased in August due to decreased emissions during the vacation period. Increases in the traffic + biomass burning source were recorded in January, April and October, which were attributed to the occurrence of the aforementioned pollution episodes and local biomass burning emission sources, which include agriculture and domestic heating systems. Average particle number concentrations (N9-825 nm) from 5/11/2010 to 01/06/2011 and from 15/10/2011 to 18/12/2011 reached 3097 cm-3. Five emission sources of particle of sub-micron particles were determined by Principal Component Analysis (PCA); industrial + traffic + biomass

  5. Source apportionment of fine PM and sub-micron particle number concentrations at a regional background site in the western Mediterranean: a 2.5 yr study

    Science.gov (United States)

    Cusack, M.; Pérez, N.; Pey, J.; Alastuey, A.; Querol, X.

    2013-02-01

    The chemical composition and sources of ambient fine particulate matter (PM1) over a period of 2.5 yr for a regional background site in the western Mediterranean are presented in this work. Major components (such as SO12-, NO3-, NH4+, organic and elemental carbon) and trace elements were analysed and the emission sources affecting PM1 were determined using Positive Matrix Factorisation (PMF). Furthermore, sub-micron particle number concentrations and the sources of these particles are also presented. Sources of sub-micron particles were determined by Principal Component Analysis (PCA). The mean PM1 concentration for the measurement period was 8.9 μg m-3, with organic matter (OM) and sulphate comprising most of the mass (3.2 and 1.5 μg m-3). A clear seasonal variation was recorded with higher PM1 concentrations in summer (11.2 μg m-3) compared to winter (6.6 μg m-3). This summer increase was due to elevated levels of sulphate and OM. Six sources were identified by PMF: secondary organic aerosol, secondary nitrate, industrial, traffic + biomass burning, fuel oil combustion and secondary sulphate. The daily variations of these sources were also determined, whereby the typically anthropogenic sources displayed elevated concentrations during the week with reductions at weekends. Nitrate levels were elevated in winter and negligible in summer, whereas secondary sulphate levels underwent a contrasting seasonal evolution with highest concentrations in summer, similar to the fuel oil combustion source. The SOA source was influenced by episodes of sustained pollution as a result of anticyclonic conditions occurring during winter, giving rise to thermal inversions and the accumulation of pollutants in the mixing layer. Increased levels in summer were owing to higher biogenic emissions and regional recirculation of air masses. The industrial source decreased in August due to decreased emissions during the vacation period. Increases in the traffic + biomass burning source

  6. Fiber Optic Particle Concentration Sensor

    Science.gov (United States)

    Boiarski, Anthony A.

    1986-01-01

    A particle concentration sensor would be useful in many industrial process monitoring applications where in situ measurements are required. These applications include determination of butterfat content of milk, percent insolubles in engine oil, and cell concentration in a bioreactor. A fiber optic probe was designed to measure particle concentration by monitoring the scattered light from the particle-light interaction at the end of a fiber-optic-based probe tip. Linear output was obtained from the sensor over a large range of particle loading for a suspension of 1.7 μm polystyrene microspheres in water and E. coli bacteria in a fermenter.

  7. Particle production in a gravitational wave background

    CERN Document Server

    Jones, Preston; Singleton, Douglas

    2016-01-01

    We study the possibility that massless particles, such as photons, are produced by a gravitational wave. That such a process should occur is implied by tree-level, Feynman diagrams such as two gravitons turning into two photons {\\it i.e.} $g + g \\rightarrow \\gamma + \\gamma$. Here we calculate the rate at which a gravitational wave creates a massless, scalar field. This is done by placing the scalar field in the background of a plane gravitational wave and calculating the 4-current of the scalar field. Even in the vacuum limit of the scalar field it has a non-zero vacuum expectation value (similar to what occurs in the Higgs mechanism) and a non-zero current. We associate this with the production of scalar field quanta by the gravitational field. This effect has potential consequences for the attenuation of gravitational waves since the massless particles are being produced at the expense of the gravitational field. This is related to the (time-dependent) Schwinger effect but with the electric field replaced b...

  8. Tribological effects of particle concentration of an iron particle suspension

    Institute of Scientific and Technical Information of China (English)

    W.C.Leung; P.L.Wong; C.Feng; W.A.Bullough

    2001-01-01

    The general friction and wear performance of an iron particulate suspension underboundary lubrication conditions are presented. The suspension is a mixture of 1-5 micrometerdiameter carbonyl iron particles with commercial hydraulic oil, which resembles typical compositionof magneto-rheological fluids. The investigation involves changing the particle concentration of thesuspension. The optimal concentration of the suspension from a tribological view point can be ob-served from the experimental results,which provides a reference to the design of the particle load-ing of magneto-rheological fluids.

  9. The large scale microwave background anisotropy in decaying particle cosmology

    International Nuclear Information System (INIS)

    We investigate the large-scale anisotropy of the microwave background radiation in cosmological models with decaying particles. The observed value of the quadrupole moment combined with other constraints gives an upper limit on the redshift of the decay z/sub d/ < 3-5. 12 refs., 2 figs

  10. The cosmic microwave background - A probe of particle physics

    Science.gov (United States)

    Silk, Joseph

    1990-01-01

    The current status of spectral distortions and angular anisotropies in the cosmic microwave background is reviewed, with emphasis on the role played by weakly interacting particle dark matter. Theoretical predictions and recent observational results are described, and prospects for future progress are summarized.

  11. Acoustic concentration of particles in fluid flow

    Science.gov (United States)

    Ward, Michael D.; Kaduchak, Gregory

    2010-11-23

    An apparatus for acoustic concentration of particles in a fluid flow includes a substantially acoustically transparent membrane and a vibration generator that define a fluid flow path therebetween. The fluid flow path is in fluid communication with a fluid source and a fluid outlet and the vibration generator is disposed adjacent the fluid flow path and is capable of producing an acoustic field in the fluid flow path. The acoustic field produces at least one pressure minima in the fluid flow path at a predetermined location within the fluid flow path and forces predetermined particles in the fluid flow path to the at least one pressure minima.

  12. Motion of test particles in a magnetized conformastatic background

    CERN Document Server

    Gutiérrez-Piñeres, Antonio C

    2015-01-01

    A class of exact conformastatic solutions of the Einstein-Maxwell field equations is presented in which the gravitational and electromagnetic potentials are completely determined by a harmonic function only. The motion of test particles is investigated in the background of a space-time characterized by this class of solutions. We focus on the study of circular stable and unstable orbits obtained by taking account particular harmonic functions defining the gravitational potential. We show that is possible to have repulsive force generated by the charge distribution of the source. As the space-time here considered is singularity free we conclude that this phenomena is not exclusive to the case of naked singularities. Additionally, we obtain an expression for the perihelion advance of the test particles in a general magnetized conformastatic space-time.

  13. Technical note: An improved approach to determining background aerosol concentrations with PILS sampling on aircraft

    Science.gov (United States)

    Fukami, Christine S.; Sullivan, Amy P.; Ryan Fulgham, S.; Murschell, Trey; Borch, Thomas; Smith, James N.; Farmer, Delphine K.

    2016-07-01

    Particle-into-Liquid Samplers (PILS) have become a standard aerosol collection technique, and are widely used in both ground and aircraft measurements in conjunction with off-line ion chromatography (IC) measurements. Accurate and precise background samples are essential to account for gas-phase components not efficiently removed and any interference in the instrument lines, collection vials or off-line analysis procedures. For aircraft sampling with PILS, backgrounds are typically taken with in-line filters to remove particles prior to sample collection once or twice per flight with more numerous backgrounds taken on the ground. Here, we use data collected during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) to demonstrate that not only are multiple background filter samples are essential to attain a representative background, but that the chemical background signals do not follow the Gaussian statistics typically assumed. Instead, the background signals for all chemical components analyzed from 137 background samples (taken from ∼78 total sampling hours over 18 flights) follow a log-normal distribution, meaning that the typical approaches of averaging background samples and/or assuming a Gaussian distribution cause an over-estimation of background samples - and thus an underestimation of sample concentrations. Our approach of deriving backgrounds from the peak of the log-normal distribution results in detection limits of 0.25, 0.32, 3.9, 0.17, 0.75 and 0.57 μg m-3 for sub-micron aerosol nitrate (NO3-), nitrite (NO2-), ammonium (NH4+), sulfate (SO42-), potassium (K+) and calcium (Ca2+), respectively. The difference in backgrounds calculated from assuming a Gaussian distribution versus a log-normal distribution were most extreme for NH4+, resulting in a background that was 1.58× that determined from fitting a log-normal distribution.

  14. Preferential concentration of heavy particles in compressible isotropic turbulence

    Science.gov (United States)

    Zhang, Qingqing; Liu, Han; Ma, Zongqiang; Xiao, Zuoli

    2016-05-01

    Numerical simulations of particle-laden compressible isotropic turbulence with Taylor Reynolds number Reλ ˜ 100 are conducted by using a high-order turbulence solver, which is based on high-order compact finite difference method in the whole flow domain and localized artificial diffusivities for discontinuities. For simplicity, only one-way coupling (i.e., the influence of fluid on particles) between the carrier flow and particles is considered. The focus is on the study of the preferential concentration of heavy particles in dissipative scale of turbulence and the underlying mechanisms. Firstly, the effect of Stokes number (St) on the particle distribution in flow of Mach 1.01 (referred to as high-Mach-number case in this study) is investigated as a necessary supplementation for the previous studies in incompressible and weakly compressible flows. It turns out that heavy particles with Stokes number close to unity exhibit the strongest preferential concentration, which is in agreement with the observation in incompressible flow. All types of heavy particles have a tendency to accumulate in high-density regions of the background flow. While all kinds of particles dominantly collect in low-vorticity regions, intermediate and large particles (St = 1 and St = 5) are also found to collect in high-vorticity regions behind the randomly formed shocklets. Secondly, the impact of turbulent Mach number (Mt) (or the compressibility) of the carrier flow on the spatial distribution of the particles with St = 1 is discussed using the simulated compressible flows with Mt being 0.22, 0.68, and 1.01, respectively. In low-Mach-number flow, particles tend to concentrate in regions of low vorticity due to the centrifuge effect of vortices and particle concentration decreases monotonically with the increasing vorticity magnitude. As Mach number increases, the degree of particle clustering is slightly weakened in low-vorticity regions but is enhanced in high-vorticity regions, which

  15. Evaluation of Background Mercury Concentrations in the SRS Groundwater System

    International Nuclear Information System (INIS)

    Mercury analyses associated with the A-01 Outfall have highlighted the importance of developing an understanding of mercury in the Savannah River Site groundwater system and associated surface water streams. This activity is critical based upon the fact that the EPA Ambient Water Quality Criteria (AWQC) for this constituent is 0.012mg/L, a level that is well below conventional detection limits of 0.1 to 0.2 mg/L. A first step in this process is obtained by utilizing the existing investment in groundwater mercury concentrations (20,242 records) maintained in the SRS geographical information management system (GIMS) database. Careful use of these data provides a technically defensible initial estimate for total recoverable mercury in background and contaminated SRS wells

  16. Evaluation of Background Mercury Concentrations in the SRS Groundwater System

    Energy Technology Data Exchange (ETDEWEB)

    Looney, B.B.

    1999-03-03

    Mercury analyses associated with the A-01 Outfall have highlighted the importance of developing an understanding of mercury in the Savannah River Site groundwater system and associated surface water streams. This activity is critical based upon the fact that the EPA Ambient Water Quality Criteria (AWQC) for this constituent is 0.012mg/L, a level that is well below conventional detection limits of 0.1 to 0.2 mg/L. A first step in this process is obtained by utilizing the existing investment in groundwater mercury concentrations (20,242 records) maintained in the SRS geographical information management system (GIMS) database. Careful use of these data provides a technically defensible initial estimate for total recoverable mercury in background and contaminated SRS wells.

  17. Trichloromethyl compounds - natural background concentrations and fates within and

    DEFF Research Database (Denmark)

    Albers, Christian Nyrop; Hansen, Poul Erik; Jacobsen, Ole Stig

    2010-01-01

    Pollution with organochlorines has received major attention due to various environmental effects, but it is now increasingly recognized, that they also take part in biogeochemical cycles and that natural background concentrations exist for several chlorinated compounds. We here report the natural....... The atmospheric input of trichloromethyl compounds is found to be minor, with significant contributions for trichloroacetic acid (TCAA), only. In top soil, where the formation of the compounds is expected to occur, there is a clear positive relationship between chloroform and trichloroacetyl containing compounds...... occurrence and cycling of organic compounds with a trichloromethyl moiety in common. The study areas are temperate coniferous forests. Trichloromethyl compounds can be found in all compartments of the forests (groundwater, soil, vegetation and throughfall), but not all compounds in all compartments...

  18. Evaluation of regional background particulate matter concentration based on vertical distribution characteristics

    Directory of Open Access Journals (Sweden)

    S. Han

    2015-05-01

    Full Text Available Heavy regional particulate matter (PM pollution in China has resulted in an important and urgent need for joint control actions among cities. It's advisable to improve the understanding of regional background concentration of PM for the development of efficient and effective joint control policies. With the increase of vertical height the influence of source emission on local air quality is weakening, but the characteristics of regional pollution gradually become obvious. A method to estimate regional background PM concentration is proposed in this paper, based on the vertical variation periodic characteristics of the atmospheric boundary layer structure and particle mass concentration, as well as the vertical distribution of particle size, chemical composition and pollution source apportionment. According to the method, the averaged regional background PM2.5 concentration, being extracted from the original time series in Tianjin, was 40.0 ± 20.2, 63.6 ± 16.9 and 53.2 ± 11.1 μg m−3, respectively, in July, August and September.

  19. The PM2.5 Fine Particle Background Network of the German Meteorological Service-First Results

    Directory of Open Access Journals (Sweden)

    Uwe Kaminski

    2013-04-01

    Full Text Available Since 2009, the measurement of the background concentration of the fine particle fraction has been a part of the climate-monitoring program of the German Meteorological Service (DWD. These particles are of high health relevance as a critical air pollutant affecting processes like the scattering and absorption of solar radiation and influencing cloud formation and visibility. At 12 weather stations, the coarse (2.5 to 10 l m and the fine particle fractions (PM2.5 are measured by means of passive and active samplers. First results are presented for the mass concentrations of coarse and fine particles as well as for the black carbon (BC content and the concentration of certain inorganic ions of fine particles. There is not only a seasonal correlation between the fraction of fine and coarse particles, but also a correlation with the location (urban background or rural background. With the help of light microscopy, coarse particles can be differentiated for a geogenic (predominantly wind blown mineral and sea salt particles of natural origin and road abrasion and for an anthropogenic opaque component (combustion residues, e.g. fly ash and non-exhaust vehicle emissions, e.g. abrasion particles of brakes and tires. Measuring the fine fraction and the coarse fraction separately instead of PM10 allows for a better source allocation and thus is a more appropriate method for the improvement of the air quality in, e.g. low emission zones.

  20. Novel Techniques for Background / Foreground Rejection in Particle Instruments Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Particle instruments in general such as mass spectrometers and plasma analyzers face two common problems that degrade their performance: (a) penetrating radiation...

  1. System for particle concentration and detection

    Science.gov (United States)

    Morales, Alfredo M.; Whaley, Josh A.; Zimmerman, Mark D.; Renzi, Ronald F.; Tran, Huu M.; Maurer, Scott M.; Munslow, William D.

    2013-03-19

    A new microfluidic system comprising an automated prototype insulator-based dielectrophoresis (iDEP) triggering microfluidic device for pathogen monitoring that can eventually be run outside the laboratory in a real world environment has been used to demonstrate the feasibility of automated trapping and detection of particles. The system broadly comprised an aerosol collector for collecting air-borne particles, an iDEP chip within which to temporarily trap the collected particles and a laser and fluorescence detector with which to induce a fluorescence signal and detect a change in that signal as particles are trapped within the iDEP chip.

  2. Gravitational Particle Production in Oscillating Background and Its Cosmological Implications

    CERN Document Server

    Ema, Yohei; Mukaida, Kyohei; Nakayama, Kazunori

    2016-01-01

    We study production of light particles due to oscillation of the Hubble parameter or the scale factor. Any coherently oscillating scalar field, irrespective of its energy fraction in the universe, imprints such an oscillating feature on them. Not only the Einstein gravity but extended gravity models, such as models with non-minimal (derivative) coupling to gravity and $f(R)$ gravity, lead to oscillation of the scale factor. We present a convenient way to estimate the gravitational particle production rate in these circumstances. Cosmological implications of gravitational particle production, such as dark matter/radiation and moduli problem, are discussed. For example, if the theory is described solely by the standard model plus the Peccei-Quinn sector, the Starobinsky $R^2$ inflation may lead to observable amount of axion dark radiation.

  3. On the concentration properties of Interacting particle processes

    CERN Document Server

    Del Moral, Pierre; Wu, Liming

    2011-01-01

    These lecture notes present some new concentration inequalities for Feynman-Kac particle processes. We analyze different types of stochastic particle models, including particle profile occupation measures, genealogical tree based evolution models, particle free energies, as well as backward Markov chain particle models. We illustrate these results with a series of topics related to computational physics and biology, stochastic optimization, signal processing and bayesian statistics, and many other probabilistic machine learning algorithms. Special emphasis is given to the stochastic modeling and the quantitative performance analysis of a series of advanced Monte Carlo methods, including particle filters, genetic type island models, Markov bridge models, interacting particle Markov chain Monte Carlo methodologies.

  4. Spatial variability of fine particle concentrations in three European areas

    Science.gov (United States)

    Hoek, Gerard; Meliefste, Kees; Cyrys, Josef; Lewné, Marie; Bellander, Tom; Brauer, Mike; Fischer, Paul; Gehring, Ulrike; Heinrich, Joachim; van Vliet, Patricia; Brunekreef, Bert

    Epidemiological studies of long-term air pollution effects have been hampered by difficulties in characterizing the spatial variation in air pollution. We conducted a study to assess the risk of long-term exposure to traffic-related air pollution for the development of inhalant allergy and asthma in children in Stockholm county, Munich and the Netherlands. Exposure to traffic-related air pollution was assessed through a 1-year monitoring program and regression modeling using exposure indicators. This paper documents the performance of the exposure monitoring strategy and the spatial variation of ambient particle concentrations. We measured the ambient concentration of PM2.5 and the reflectance of PM2.5 filters ('soot') at 40-42 sites representative of different exposure conditions of the three study populations. Each site was measured during four 14-day average sampling periods spread over one year (spring 1999 to summer 2000). In each study area, a continuous measurement site was operated to remove potential bias due to temporal variation. The selected approach was an efficient method to characterize spatial differences in annual average concentration between a large number of sites in each study area. Adjustment with data from the continuous measurement site improved the precision of the calculated annual averages, especially for PM2.5. Annual average PM2.5 concentrations ranged from 11 to 20 μg/m 3 in Munich, from 8 to 16 μg/m 3 in Stockholm and from 14 to 26 μg/m 3 in the Netherlands. Larger spatial contrasts were found for the absorption coefficient of PM2.5. PM2.5 concentrations were on average 17-18% higher at traffic sites than at urban background sites, but PM2.5 absorption coefficients at traffic sites were between 31% and 55% increased above background. This suggests that spatial variation of traffic-related air pollution may be underestimated if PM2.5 only is measured.

  5. Brownian coagulation at high particle concentrations

    NARCIS (Netherlands)

    Trzeciak, T. M.

    2012-01-01

    The process of Brownian coagulation, whereby particles are brought together by thermal motion and grow by collisions, is one of the most fundamental processes influencing the final properties of particulate matter in a variety of technically important systems. It is of importance in colloids, emulsi

  6. Brownian coagulation at high particle concentrations

    OpenAIRE

    Trzeciak, T. M.

    2012-01-01

    The process of Brownian coagulation, whereby particles are brought together by thermal motion and grow by collisions, is one of the most fundamental processes influencing the final properties of particulate matter in a variety of technically important systems. It is of importance in colloids, emulsions, flocculation, air pollution, soot formation, materials manufacture and growth of interstellar dust, to name a few of its applications. With continuous progress in particulate matter processing...

  7. Classical and quantum particle dynamics in univariate background fields

    CERN Document Server

    Heinzl, Thomas; King, Ben

    2016-01-01

    We investigate deviations from the plane wave model in the interaction of charged particles with strong electromagnetic fields. A general result is that integrability of the dynamics is lost when going from lightlike to timelike or spacelike field dependence. For a special scenario in the classical regime we show how the radiation spectrum in the spacelike (undulator) case becomes well-approximated by the plane wave model in the high energy limit, despite the two systems being Lorentz inequivalent. In the quantum problem, there is no analogue of the WKB-exact Volkov solution. Nevertheless, WKB and uniform-WKB approaches give good approximations in all cases considered. Other approaches that reduce the underlying differential equations from second to first order are found to miss the correct physics for situations corresponding to barrier transmission and wide-angle scattering.

  8. THEORETICAL ANALYSIS ON THE VERTICAL DISTRIBUTION OF PARTICLE CONCENTRATION

    Institute of Scientific and Technical Information of China (English)

    Guangqian WANG; Xudong FU

    2001-01-01

    In steady, solid-liquid two-phase turbulent flows, there exist two typical patterns of the vertical distribution of particle concentration. The pattern I shows a maximum concentration at an elevation above the bed. The pattern II shows an increase of the particle concentration downward over the whole vertical,with the maximum at the bed. Most of the theories on particle concentration distribution have been done with the pattern II, and it is lack of a successful theory coveting both of the two patterns. This paper reviews the particle distribution theories, including the diffusion theory, the mixture theory, the energy theory, the similarity theory, the stochastic theory and the kinetic theory. The kinetic theory is also applied to describe the vertical distribution of particle concentration in both dilute and dense flows.

  9. Variation of particle number concentration and size distributions at the urban environment in Vilnius (Lithuania)

    Science.gov (United States)

    Ulevicius, Vidmantas; Byčenkienë, Steigvilë; Plauškaitë, Kristina; Dudoitis, Vadimas

    2013-05-01

    This study presents results of research on urban aerosol particles with a focus on the particle size distribution and the aerosol particle number concentration (PNC). The real time measurements of the aerosol PNC in the size range of 9-840 nm were performed at the urban background site using a Condensed Particle Counter and Scanning Mobility Particle Sizer (SMPS). Strong diurnal patterns in aerosol PNC were evident as a direct effect of three sources of the aerosol particles (nucleation, traffic, and residential heating appliances). The traffic exhaust emissions were a major contributor of the pollution observed at the roadside site that was dominated by the nucleation mode particles, while particles formed due to the residential heating appliances and secondary formation processes contributed to the accumulation mode particles and could impact the variation of PNC and its size distribution during the same day.

  10. Optical sensor technology for simultaneous measurement of particle speed and concentration of micro sized particles

    DEFF Research Database (Denmark)

    Clausen, Casper; Han, Anpan; Kristensen, Martin;

    2013-01-01

    Experimental characterization of a sensor technology that can measure particle speed and concentration simultaneously in liquids and gases is presented here. The basic sensor principle is based on an optical element that shapes a light beam into well-defined fringes. The technology can be described...... as a hybrid between Laser Doppler Velocimetry and Laser Particle Counters. The experimental characterization of a lab-scale setup has been performed with polystyrene particles in the range from 750 nm to 20 μm, with various particle speeds. It is shown that particle concentrations can be determined...... independently from particle speeds and is a key advantage compared to normal Laser Particle Counters....

  11. Intercomparison of number concentration measurements by various aerosol particle counters

    Science.gov (United States)

    Ankilov, A.; Baklanov, A.; Colhoun, M.; Enderle, K.-H.; Gras, J.; Julanov, Yu.; Kaller, D.; Lindner, A.; Lushnikov, A. A.; Mavliev, R.; McGovern, F.; Mirme, A.; O'Connor, T. C.; Podzimek, J.; Preining, O.; Reischl, G. P.; Rudolf, R.; Sem, G. J.; Szymanski, W. W.; Tamm, E.; Vrtala, A. E.; Wagner, P. E.; Winklmayr, W.; Zagaynov, V.

    Total aerosol particle number concentrations, as measured by means of 16 different measurement systems, have been quantitatively compared during an international workshop at the Institute for Experimental Physics of the University of Vienna, Austria, which was coordinated within the Committee on Nucleation and Atmospheric Aerosols (ICCP-IUGG). The range of measuring instruments includes Pollak counters (PCO) in use already for several decades, presently available commercial particle counters, as well as laboratory prototypes. The operation of the instruments considered was based on different measurement principles: (1) adiabatic expansion condensation particle counter, (2) flow diffusion condensation particle counter, (3) turbulent mixing condensation particle counter, (4) laser optical particle counter, and (5) electrostatic particle measurement system. Well-defined test aerosols with various chemical compositions were considered: DEHS, sodium chloride, silver, hydrocarbons, and tungsten oxide. The test aerosols were nearly monodispersed with mean particle diameters between 4 and 520 nm, the particle number concentrations were varied over a range from about 4×10 1 to 7×10 6 cm -3. A few measurements were performed with two-component aerosol mixtures. For simultaneous concentration measurements, the various instruments considered were operated under steady state conditions in a linear flow system. A series of at least 10 single concentration measurements was performed by each individual instrument at each set of test aerosol parameters. The average of the concentration data measured by the various instruments was defined as a common reference. The number concentrations obtained from the various instruments typically agreed within a factor of about two over the entire concentration range considered. The agreement of the measured concentrations is notable considering the various different measurement principles applied in this study, and particularly in view of the

  12. Nonrelativistic Charged Particle-Magnetic Monopole Scattering in the Global Monopole Background

    CERN Document Server

    De Oliveira, A L C

    2003-01-01

    We analyze the nonrelativistic quantum scattering problem of a charged particle by an Abelian magnetic monopole in the background of a global monopole. In addition to the magnetic and geometric effects, we consider the influence of the electrostatic self-interaction on the charged particle. Moreover, for the specific case where the electrostatic self-interaction becomes attractive, charged particle-monopole bound system can be formed and the respective energy spectrum is hydrogen-like one.

  13. CO2 background concentra-tion in the atmosphere over the Chinese mainland

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on the long-term monitoring data on CO2 concentration, variation trend and characteristics of CO2 background concentration in the atmosphere over the Chinese mainland are analyzed. Results show that the increasing trend of CO2 background concentration in the atmosphere over the Chinese mainland has appeared during the period of 1991-2000. The average annual CO2 growth increment is 1.59 μL/L, and the average annual CO2 growth rate is 0.44%. Distinct seasonal variations of CO2 background concentration are observed, and the averaged amplitude of CO2 seasonal variations is 10.35 μL/L. Regional variation characteristics of CO2 background concentration in the atmosphere and possible impact of human activities on these variations over the Chinese mainland are discussed as well.

  14. The measurement and parameterization of ice nucleating particles in different backgrounds of China

    Science.gov (United States)

    Jiang, Hui; Yin, Yan; Wang, Xu; Gao, Renjie; Yuan, Liang; Chen, Kui; Shan, Yunpeng

    2016-11-01

    Investigation of the number concentration of ice nucleating particles (INP) in the deposition nucleation mode during a dust event is reported. The results discussed in this paper are the first continuous INP measurements in Xinjiang, northwest of China, over a period with a strong dust event. The average INP concentration at - 20 °C and 22% of supersaturation with respect to ice during non-dust days is found around 11 particles per liter, but it reached several hundred per liter in a dust event. A close correlation is also found between the INP number concentration with the number concentration of aerosol particles larger than 0.5 μm in diameter measured during a dust event, which means that a higher concentration of larger particles induced higher INP number concentration. Parameterizations were developed based on measurements to represent the variations of INP concentration with temperature, supersaturation, and the number concentration of aerosol particles with size larger than 0.5 μm. It should be the first ever, as we have known so far, to measure ice nuclei and aerosol properties simultaneously in a desert area and to contrast INP concentrations in dust and dust-free days, and could advancing our understanding of the effects of dust particles on ice nucleation.

  15. Long-term study on the impact of new particle formation on CCN in an urban background location

    Science.gov (United States)

    Dameto de Espana, María del Carmen; Wonaschuetz, Anna; Demattio, Anselm; Steiner, Gerhard; Hitzenberger, Regina

    2015-04-01

    New Particles Formation (NPF) events and Cloud Condensation Nuclei (CCN) have been investigated intensively over the last years. Measurements have been performed at many different locations. Several studies suggest that NPF significantly enhance atmospheric CCN concentrations. Only few studies, however, linked nucleation measurements directly to increases in measured CCN concentrations. Most of these studies were performed in remote or background locations. There is a lack of continuous long-term measurements of CCN concentrations in the urban background. In order to provide more information about NPF acting as a source of CCN, a long term study was started in June 2014 in the urban background of Vienna and is planned to continue for the foreseeable future. The measurements are performed at the aerosol laboratory located on the rooftop (35m above ground) of the Physics building of the University of Vienna, located in central Vienna. Concentrations as well as seasonal characteristics of CCN concentrations and NPF events will be investigated. A CCNC (Cloud Condensation Nuclei Counter) designed at the University of Vienna operating on the principle of a static thermal diffusion chamber (Giebl et al., 2002), is used to measure CCN concentrations and activation ratios for low supersaturations (0,5%). NPF events are determined with a Vienna-type DMPS (Differential Mobility Particle Sizer, Winkelmayr et al., 1991) and classified using the criteria of Dal Maso et al., (2005). NPF events cannot always be identified completely clearly because of local pollution plumes. Traffic emissions could additionally increase the concentration of organic particles during a NPF event. A Multi Angle Absorption Photometer (MAAP) measuring black carbon concentration is therefore used to monitor the contribution of traffic emissions to the aerosol at the station.

  16. Contribution of ship traffic to aerosol particle concentrations downwind of a major shipping lane

    DEFF Research Database (Denmark)

    Kivekäs, N.; Massling, Andreas; Grythe, H.;

    2014-01-01

    Particles in the atmosphere are of concern due to their toxic properties and effects on climate. In coastal areas, ship emissions can be a significant anthropogenic source. In this study we investigated the contribution from ship emissions to the total particle number and mass concentrations...... at a remote location. We studied the particle number concentration (12 to 490 nm in diameter), the mass concentration (12 to 150 nm in diameter) and number and volume size distribution of aerosol particles in ship plumes for a period of 4.5 months at Hovsore, a coastal site on the western coast of Jutland...... in Denmark. During episodes of western winds, the site is about 50 km downwind of a major shipping lane and the plumes are approximately 1 hour old when they arrive at the site. We have used a sliding percentile-based method for separating the plumes from the measured background values and to calculate...

  17. Personal exposure to grass pollen: relating inhaled dose to background concentration

    DEFF Research Database (Denmark)

    Peel, Robert George; Hertel, Ole; Smith, Matt;

    2013-01-01

    . A 2003 World Health Organization report highlighted the need for an improved understanding of the relation between monitoring station data and actual exposure. Objective: To investigate the relation between grass pollen dose and background concentrations measured at a monitoring station, to assess...... the fidelity of monitoring station data as a qualitative proxy for dose, and to evaluate the ratio of dose rate to background concentration. Methods: Grass pollen dose data were collected in Aarhus, Denmark, in an area where grass pollen sources were prevalent, using Nasal Air Samplers. Sample collection...... of day when grass species likely to be present in the area are expected to flower. From 4 to 8 PM, dose rate and background concentration data were found to be strongly and significantly correlated (r(s) = 0.81). Averaged dose rate and background concentration data showed opposing temporal trends...

  18. Cosmic background radiation spectral distortion and radiative decays of relic neutral particles

    International Nuclear Information System (INIS)

    The recently observed excess of photons on a short wavelength side of the peak of a cosmic background radiation spectrum can be described by radiative decays of relic neutral particles. The lifetime and mass of a decaying particle must satisfy the following conditions: 2x109 s14 s, 0.4 eV-9-8x10-8) μb, and the interaction of new particles with the usual matter must be rather strong. The generalization of the standard SU(3)xSU(2)xU(1) model is presented which includes new particles with the desired properties. 18 refs.; 3 figs.; 2 tabs

  19. Lipoprotein particle concentrations in children and adults following kawasaki disease

    OpenAIRE

    Lin, J.; S. Jain; X. Sun; Liu, V; Sato, YZ; Jimenez-Fernandez, S; Newfield, RS; Pourfarzib, R; Tremoulet, AH; Gordon, JB; Daniels, LB; Burns, JC

    2014-01-01

    Objective: To test the hypothesis that children and adults with a history of Kawasaki disease (KD) are more likely to have abnormal lipoprotein particle profiles that could place them at increased risk for developing atherosclerosis later in life. Study design: Fasting serum samples were obtained from 192 children and 63 adults with history of KD and 90 age-similar healthy controls. Lipoprotein particle concentrations and sizes were measured by nuclear magnetic resonance spectroscopy (LipoSci...

  20. Lipoprotein Particle Concentrations in Children and Adults following Kawasaki Disease

    OpenAIRE

    J. Lin; Jain, S; X. Sun; Liu, V.; Sato, YZ; Jimenez-Fernandez, S; Newfield, RS; Pourfarzib, R; Tremoulet, AH; Gordon, JB; Daniels, LB; Burns, JC

    2014-01-01

    Objective: To test the hypothesis that children and adults with a history of Kawasaki disease (KD) are more likely to have abnormal lipoprotein particle profiles that could place them at increased risk for developing atherosclerosis later in life. Study design: Fasting serum samples were obtained from 192 children and 63 adults with history of KD and 90 age-similar healthy controls. Lipoprotein particle concentrations and sizes were measured by nuclear magnetic resonance spectroscopy (LipoSci...

  1. Lipoprotein particle concentrations in children and adults following kawasaki disease

    OpenAIRE

    J. Lin; Jain, S; X. Sun; Liu, V.; Sato, YZ; Jimenez-Fernandez, S; Newfield, RS; Pourfarzib, R; Tremoulet, AH; Gordon, JB; Daniels, LB; Burns, JC

    2014-01-01

    © 2014 Elsevier Inc. Objective To test the hypothesis that children and adults with a history of Kawasaki disease (KD) are more likely to have abnormal lipoprotein particle profiles that could place them at increased risk for developing atherosclerosis later in life. Study design Fasting serum samples were obtained from 192 children and 63 adults with history of KD and 90 age-similar healthy controls. Lipoprotein particle concentrations and sizes were measured by nuclear magnetic resonance sp...

  2. Correlation between work concentration level and background music: a pilot study.

    Science.gov (United States)

    Shih, Yi-Nuo; Huang, Rong-Hwa; Chiang, Han-Sun

    2009-01-01

    It is a common phenomenon for office workers {to listen to music} while executing daily routines at their desks. The aim of this study was to investigate the correlation between work concentration level and background music. This research would first follow examples in previous researches, and then explore the influence of background music on participants' scores on attention tests. We hope to gain a preliminary understanding of the possible influence of background music on people's focus and concentration when doing work. Thirty-two college students were separated into three controlled groups; all were given the attention test. Group [a] listened to background music while being tested for 10 minutes; group [b] had no background music at all; and group [c] listened to the music for 10 minutes prior to the attention test. The test was conducted in a "noise free" environment. The means and error rates for each group were then calculated. The findings showed that, in comparison with "no music at all", those who listened to music prior to testing obtained higher scores in attentiveness (most probably a supplemental effect of the music), whereas those who listened to music during attention test showed extremely high level of variation in attention test scoring. Background music does affect people's job-site behavior. In fact, all three test conditions - no background music at all, background music before the work shift, and background music during work - have affected worker performance on different levels. PMID:19759431

  3. Transit time of a freely-falling quantum particle in a background gravitational field

    OpenAIRE

    Davies, P.C.W.

    2004-01-01

    Using a model quantum clock, I evaluate an expression for the time of a non-relativistic quantum particle to transit a piecewise geodesic path in a background gravitational field with small spacetime curvature (gravity gradient), in the case that the apparatus is in free fall. This calculation complements and extends an earlier one (Davies 2004) in which the apparatus is fixed to the surface of the Earth. The result confirms that, for particle velocities not too low, the quantum and classical...

  4. Spatial & temporal variations of PM10 and particle number concentrations in urban air.

    Science.gov (United States)

    Johansson, Christer; Norman, Michael; Gidhagen, Lars

    2007-04-01

    The size of particles in urban air varies over four orders of magnitude (from 0.001 microm to 10 microm in diameter). In many cities only particle mass concentrations (PM10, i.e. particles sand on streets during winter; up to 90% of the locally emitted PM10 may be due to road abrasion. PM10 emissions and concentrations, but not PNC, at kerbside are controlled by road moisture. Annual mean urban background PM10 levels are relatively uniformly distributed over the city, due to the importance of long range transport. For PNC local sources often dominate the concentrations resulting in large temporal and spatial gradients in the concentrations. Despite these differences in the origin of PM10 and PNC, the spatial gradients of annual mean concentrations due to local sources are of equal magnitude due to the common source, namely traffic. Thus, people in different areas experiencing a factor of 2 different annual PM10 exposure due to local sources will also experience a factor of 2 different exposure in terms of PNC. This implies that health impact studies based solely on spatial differences in annual exposure to PM10 may not separate differences in health effects due to ultrafine and coarse particles. On the other hand, health effect assessments based on time series exposure analysis of PM10 and PNC, should be able to observe differences in health effects of ultrafine particles versus coarse particles.

  5. Pseudoclassical description of scalar particle in non-Abelian background and path-integral representations

    CERN Document Server

    Fresneda, R

    2007-01-01

    Path-integral representations for a scalar particle propagator in non-Abelian external backgrounds are derived. To this aim, we generalize the procedure proposed by Gitman and Schvartsman 1993 of path-integral construction to any representation of SU(N) given in terms of antisymmetric generators. And for arbitrary representations of SU(N), we present an alternative construction by means of fermionic coherent states. From the path-integral representations we derive pseudoclassical actions for a scalar particle placed in non-Abelian backgrounds. These actions are classically analyzed and then quantized to prove their consistency.

  6. PM10 concentration levels at an urban and background site in Cyprus: the impact of urban sources and dust storms.

    Science.gov (United States)

    Achilleos, Souzana; Evans, John S; Yiallouros, Panayiotis K; Kleanthous, Savvas; Schwartz, Joel; Koutrakis, Petros

    2014-12-01

    Air quality in Cyprus is influenced by both local and transported pollution, including desert dust storms. We examined PM10 concentration data collected in Nicosia (urban representative) from April 1, 1993, through December 11, 2008, and in Ayia Marina (rural background representative) from January 1, 1999, through December 31, 2008. Measurements were conducted using a Tapered Element Oscillating Micro-balance (TEOM). PM10 concentrations, meteorological records, and satellite data were used to identify dust storm days. We investigated long-term trends using a Generalized Additive Model (GAM) after controlling for day of week, month, temperature, wind speed, and relative humidity. In Nicosia, annual PM10 concentrations ranged from 50.4 to 63.8 μg/m3 and exceeded the EU annual standard limit enacted in 2005 of 40 μg/m3 every year A large, statistically significant impact of urban sources (defined as the difference between urban and background levels) was seen in Nicosia over the period 2000-2008, and was highest during traffic hours, weekdays, cold months, and low wind conditions. Our estimate of the mean (standard error) contribution of urban sources to the daily ambient PM10 was 24.0 (0.4) μg/m3. The study of yearly trends showed that PM10 levels in Nicosia decreased from 59.4 μg/m3 in 1993 to 49.0 μg/m3 in 2008, probably in part as a result of traffic emission control policies in Cyprus. In Ayia Marina, annual concentrations ranged from 27.3 to 35.6 μg/m3, and no obvious time trends were observed. The levels measured at the Cyprus background site are comparable to background concentrations reported in other Eastern Mediterranean countries. Average daily PM10 concentrations during desert dust storms were around 100 μg/m3 since 2000 and much higher in earlier years. Despite the large impact ofdust storms and their increasing frequency over time, dust storms were responsible for a small fraction of the exceedances of the daily PM10 limit. Implications: This

  7. Ultrasonic spectrum for particle concentration measurement in multicomponent suspensions

    Science.gov (United States)

    Zhan, Xiaobin; Jiang, Shulan; Yang, Yili; Liang, Jian; Shi, Tielin; Li, Xiwen

    2016-02-01

    This paper studies the feasibility of applying the ultrasonic spectrum technique to the measurement of particle concentrations in multicomponent suspensions. A combination of the kernel partial least squares (KPLS) model and the interval selection methods is implemented to build the relationship between the ultrasonic spectra of the first reflected pulses and the particle concentrations. First of all, the interval selection methods are used to select optimal spectral interval(s) from full spectra. Then, the KPLS models with optimal spectral interval(s) are tuned, built and evaluated to obtain the optimal model. Finally, the optimal KPLS model is employed to measure the particle concentrations in the mixing process and its online prediction ability is evaluated. In comparison with the linear partial least squares (PLS) models, the optimal KPLS model shows the best performance. The results demonstrate that particle concentrations in multicomponent suspensions can be measured online by the ultrasonic spectrum technique, and the KPLS model with optimal spectral interval(s) shows the superiority in model calibration.

  8. Modeling Lost-Particle Accelerator Backgrounds in PEP-II Using LPTURTLE

    CERN Document Server

    Fieguth, Theodore; Kozanecki, Witold

    2005-01-01

    Background studies during the design, construction, commissioning, operation and improvement of BaBar and PEP-II have been greatly influenced by results from a program referred to as LPTURTLE (Lost Particle TURTLE a modified version of Decay TURTLE) which was originally conceived for the purpose of studying gas background for SLC. This venerable program is still in use today. We describe its use, capabilities and improvements and refer to current results now being applied to BaBar.

  9. Characterisation of particle emissions from the driving car fleet and the contribution to ambient and indoor particle concentrations

    Science.gov (United States)

    Palmgren, Finn; Wåhlin, Peter; Kildesø, Jan; Afshari, Alireza; Fogh, Christian L.

    The population is mainly exposed to high air pollution concentrations in the urban environment, where motor vehicle emissions constitute the main source of fine and ultrafine particles. These particles can penetrate deep into the respiratory system, and studies indicate that the smaller the particle, the larger the health impacts. The chemical composition, surface reactivity and physical properties are also important. However, the knowledge about chemical and physical properties of particles and the temporal and spatial variability of the smallest particles is still very limited. The present study summarises the first results of a larger project with the aims to improve the knowledge. The concentration and the emissions of ultrafine particles from petrol and diesel vehicles, respectively, have been quantified using Scanning Mobility Particle Sizer of ultrafine particles in the size range 6-700 nm and routine monitoring data from urban streets and urban background in Denmark. The quantification was carried out using receptor modelling. The number size distributions of petrol and diesel emissions showed a maximum at 20-30 nm and non-traffic at ≈100 nm. The contribution of ultrafine particles from diesel vehicles is dominating in streets. The same technique has been applied on PM 10, and ≈50% contribution from non-traffic. The technique has also been introduced in relation to elemental and organic carbon, and the first data showed strong correlation between traffic pollution and elemental carbon. The outdoor air quality has a significant effect on indoor pollution levels, and we spend most of the time indoors. Knowledge about the influence of ambient air pollution on the concentrations in the indoor environment is therefore crucial for assessment of human health effects of traffic pollution. The results of our studies will be included in air quality models for calculation of human exposure. Preliminary results from our first campaign showed, that the deposition

  10. Determination of Solid Particle Concentration at coal Transshipment site

    Science.gov (United States)

    Siliņš, K.; Žandeckis, A.; Valtere, S.

    2009-01-01

    Coal handling and grinding processes are associated with significant particulate matter emissions into the atmosphere. This problem is particularly urgent when a coal-processing company is located in or nearby a densely populated city. To quantitatively evaluate concentrations generated into the atmosphere according to the standardized methodology, it is necessary to make extensive measurements using an automatic real-time, infrared dust and aerosol monitor. Before the experiments, the impact of particulate matter on human health and the environment was explored, six solid particle concentration detection methods and best available techniques for particulate matter emission prevention was described. During this study field measurements were carried out at on the territory of a coal transshipment company. Using the solid particle concentration detection system Dust Detective kit, concentration monitoring of total particulate matter (TSP), PM10 and PM2.5 was carried out. The equipment was located 6 m above ground and 120 m away from the emission source - coal crushing and handling site. TSP monitoring was carried out during four diurnal, PM10 - during 17 diunral and PM2.5 - during 12 days. After comparison of results with concentration values set in normative documents of Latvia and EU, it was found out that average 17 diurnal day concentration values of PM10 exceeded normative values for nine times. PM2.5 daily average concentrations of 12 days exceeded for four times exceeded the value of 25 μg/m3, which is mentioned in Directive 2008/50/EC of EU. After analysis of wind behaviour impact on the concentration values it is now understood that if wind comes from the dust emission source to the measurement system, the increase in wind speed increases particle concentration as all particles in the air and those raised from coal piles are driven towards the equipment. If wind comes from the opposite direction, the decrease of wind velocity results in an increase of

  11. Genesis Concentrator Target Particle Contamination Mapping and Material Identification

    Science.gov (United States)

    Calaway, Michael J.; Rodriquez, M. C.; Allton, J. H.

    2007-01-01

    The majority of surface particles were found to be Genesis science team as well as ultra-pure water megasonic cleaning by the JSC team [4]. Removal of organic contamination from target materials is also being investigated by the science team with the use of UV-ozone cleaning devices at JSC and Open University [5]. In preparation for solar wind oxygen analyses at UCLA and Open University [1, 2], surface particle contamination on three Genesis concentrator targets was closely examined to evaluate cleaning strategies. Two silicon carbide (Genesis sample # 60001 and 60003) and one chemical vapor deposited (CVD) 13C concentrator target (60002) were imaged and mosaic mapped with optical microscopes. The resulting full target mosaic images and particle feature maps were subsequently compared with non-flight, but flight-like, concentrator targets and sample return capsule (SRC) materials. Contamination found on the flown concentrator acceleration grid was further examined using a scanning electron microscope (SEM). Energy dispersive X-ray spectroscopy (EDS) for particle identification was subsequently compared with the optical images from the flown targets. Figure 1 show that all three targets imaged in this report are fully intact and do not show any signs of material fractures. However, previous ellipsometry results and overview imaging of both flown SiC targets show a solar wind irradiation gradient from the center focal point to the outer edge [3]. In addition, due to the hard landing, each target has experienced varying degrees of impacts, scratches, and particle debris from the spacecraft and Utah impact site.

  12. Monitoring atmospheric nitrous oxide background concentrations at Zhongshan Station, east Antarctica.

    Science.gov (United States)

    Ye, Wenjuan; Bian, Lingen; Wang, Can; Zhu, Renbin; Zheng, Xiangdong; Ding, Minghu

    2016-09-01

    At present, continuous observation data for atmospheric nitrous oxide (N2O) concentrations are still lacking, especially in east Antarctica. In this paper, nitrous oxide background concentrations were measured at Zhongshan Station (69°22'25″S, 76°22'14″E), east Antarctica during the period of 2008-2012, and their interannual and seasonal characteristics were analyzed and discussed. The mean N2O concentration was 321.9nL/L with the range of 320.5-324.8nL/L during the five years, and it has been increasing at a rate of 0.29% year(-1). Atmospheric N2O concentrations showed a strong seasonal fluctuation during these five years. The concentrations appeared to follow a downtrend from spring to autumn, and then increased in winter. Generally the highest concentrations occurred in spring. This trend was very similar to that observed at other global observation sites. The overall N2O concentration at the selected global sites showed an increasing annual trend, and the mean N2O concentration in the Northern Hemisphere was slightly higher than that in the Southern Hemisphere. Our result could be representative of atmospheric N2O background levels at the global scale. This study provided valuable data for atmospheric N2O concentrations in east Antarctica, which is important to study on the relationships between N2O emissions and climate change. PMID:27593286

  13. Attention Drainage Effect: How Background Music Effects Concentration in Taiwanese College Students

    Science.gov (United States)

    Chou, Peter Tze-Ming

    2010-01-01

    The purpose of this study was to see whether different types of background music affect the performance of a reading comprehension task in Taiwanese college students. There are two major research questions in this study. First, this study tries to find out whether listening to music affect the learner's concentration when they are doing a task…

  14. Background concentrations of radionuclides in soils and river sediments in northern New Mexico, 1974-1986

    Energy Technology Data Exchange (ETDEWEB)

    Purtymun, W.D.; Peters, R.J.; Buhl, T.E.; Maes, M.N.; Brown, F.H.

    1987-11-01

    This report documents the range and the upper limit for background concentrations of radionuclides and radioactivity in soils and river sediments that occur as natural rock-forming minerals and worldwide fallout from atmospheric nuclear weapons tests. Documentation is based on the collection of soil and sediment in northern New Mexico and analyzed for /sup 137/Cs, /sup 238/Pu, /sup 239,240/Pu, /sup 90/Sr, total uranium, gross gamma, and tritium. The data used to establish the statistical range and upper limit of background concentration cover a 9- or 13-year period ending in 1986. The knowledge of background levels is necessary to interpret soil and sediment data collected for the annual environmental surveillance report and other reports relating to radionuclides or radioactivity in soils and sediments. 11 refs., 1 fig., 5 tabs.

  15. Acoustic resonance scattering by a system of concentrically multilayered shells: the inherent background and resonance coefficients

    CERN Document Server

    Choi, M S; Lee, S H

    1999-01-01

    The inherent background coefficients that exactly describe the background amplitudes in the scattered field have been presented for the scattering of plane acoustic waves by a system of concentrically multilayered solid and/or fluid shells submerged in a fluid. The coefficients have been obtained by replacing the mechanical surface admittance function with the zero-frequency limit of the admittance function for the analogous fluid system, where the shear wave speeds in the solid layers are set to zero. By taking advantage of the concept of incoming and outgoing waves, we find the surface admittance function for the fluid system in such a form that the analytical generalization for any number of layers and the physical interpretation are very easy. The background coefficients obtained are independent of the bulk wave speeds in the system: they depend on the mass densities and the thickness of the shells. With increasing frequency, the inherent background undergoes a transition from the soft to the rigid backgr...

  16. A simple algorithm for measuring particle size distributions on an uneven background from TEM images

    DEFF Research Database (Denmark)

    Gontard, Lionel Cervera; Ozkaya, Dogan; Dunin-Borkowski, Rafal E.

    2011-01-01

    Nanoparticles have a wide range of applications in science and technology. Their sizes are often measured using transmission electron microscopy (TEM) or X-ray diffraction. Here, we describe a simple computer algorithm for measuring particle size distributions from TEM images in the presence of an...... uneven background. The approach is based on adaptive thresholding, making use of local threshold values that change with spatial coordinate. The algorithm allows particles to be detected and characterized with greater accuracy than using more conventional methods, in which a global threshold is used. Its...

  17. Applying alpha particle background ionization device in the development of pulsed nitrogen laser technology

    International Nuclear Information System (INIS)

    An investigation on the application of alpha particles in the induction of a bias ionized background plasma before, during and after the discharge of the N2 TE UV laser (337.1 nm), built in the LEL-IF/UFF is presented. The alpha particles are provided by Americium (241-Am) stripes placed inside the discharge channel of the laser device. The stimulated radiation output characteristics, in terms of gas pressure, charging voltage and pulse width, of a N2 TE UV laser (337.1 nm) circuit are presented. The increased laser yield is interpreted qualitatively through plasma impedance in the discharge circuit. (author)

  18. Applying alpha particle background ionization device in the development of pulsed nitrogen laser technology

    Energy Technology Data Exchange (ETDEWEB)

    Fellows, C.E.; Rodegheri, C.C.; Tauber, U. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Fisica. Lab. de Espectroscopia e Laser (LEL); Guterres, R.F. [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil). Coordenacao de Instalacoes Radiativas]. E-mail: rgutterr@cnen.gov.br

    2005-11-15

    An investigation on the application of alpha particles in the induction of a bias ionized background plasma before, during and after the discharge of the N2 TE UV laser (337.1 nm), built in the LEL-IF/UFF is presented. The alpha particles are provided by Americium (241-Am) stripes placed inside the discharge channel of the laser device. The stimulated radiation output characteristics, in terms of gas pressure, charging voltage and pulse width, of a N2 TE UV laser (337.1 nm) circuit are presented. The increased laser yield is interpreted qualitatively through plasma impedance in the discharge circuit. (author)

  19. Estimation of appropriate background concentrations for assessing mercury contamination in fish

    International Nuclear Information System (INIS)

    One goal of environmental restoration at contaminated industrial or hazardous waste sites is the prevention of any further release of contaminants. As a consequence of successful remediation, it is hoped that elevated contaminant concentrations in biota will return to levels characteristic of environments uncontaminated by point sources. To evaluate the efficacy of such an environmental cleanup, it is necessary to know what background contaminant concentrations would typify uncontaminated conditions in the systems of interest. An accurate estimate of an appropriate background mercury concentration in fish is needed to determine the extent to which industrial mercury discharges produce elevated mercury concentration in fish in receiving waters, and to determine the concentration in fish that would represent restoration to uncontaminated status. Losses of large quantities of mercury in the 1950s at the U.S. Department of Energy (DOE) facilities in Oak Ridge, Tennessee resulted in continued chronic contamination of several small streams and the downstream river/reservoir system. mercury concentrations in axial muscle of fish exceed 1 μg/g wet wt. near the source, and decline to much lower concentrations 20 km downstream in Watts Bar Reservoir. Although remedial efforts are underway, the facility remains a continuing source of mercury contamination to the downstream waters. This study measures mercury concentration in bluegill and redbreast sunfish from streams and reservoirs near Oak Ridge, TN that are presumed to be relatively unimpacted by anthropogenic point sources of mercury to determine appropriate background levels in fish to apply in evaluating local contaminated streams and reservoirs. 16 refs., 1 fig., 1 tab

  20. Outdoor ultrafine particle concentrations in front of fast food restaurants.

    Science.gov (United States)

    Vert, Cristina; Meliefste, Kees; Hoek, Gerard

    2016-01-01

    Ultrafine particles (UFPs) have been associated with negative effects on human health. Emissions from motor vehicles are the principal source of UFPs in urban air. A study in Vancouver suggested that UFP concentrations were related to density of fast food restaurants near the monitoring sites. A previous monitoring campaign could not separate the contribution of restaurants from road traffic. The main goal of this study has been the quantification of fast food restaurants' contribution to outdoor UFP concentrations. A portable particle number counter (DiscMini) has been used to carry out mobile monitoring in a largely pedestrianized area in the city center of Utrecht. A fixed route passing 17 fast food restaurants was followed on 8 days. UFP concentrations in front of the restaurants were 1.61 times higher than in a nearby square without any local sources used as control area and 1.22 times higher compared with all measurements conducted in between the restaurants. Adjustment for other sources such as passing mopeds, smokers or candles did not explain the increase. In conclusion, fast food restaurants result in significant increases in outdoor UFP concentrations in front of the restaurant. PMID:26531805

  1. Particle number concentrations over Europe in 2030: the role of emissions and new particle formation

    Directory of Open Access Journals (Sweden)

    L. Ahlm

    2013-04-01

    Full Text Available The aerosol particle number concentration is a key parameter when estimating impacts of aerosol particles on climate and human health. We use a three-dimensional chemical transport model with detailed microphysics, PMCAMx-UF, to simulate particle number concentrations over Europe in the year 2030, by applying emission scenarios for trace gases and primary aerosols. The scenarios are based on expected changes in anthropogenic emissions of sulphur dioxide, ammonia, nitrogen oxides, and primary aerosol particles with a diameter less than 2.5 μm (PM2.5 focusing on a photochemically active period. For the baseline scenario, which represents a best estimate of the evolution of anthropogenic emissions in Europe, PMCAMx-UF predicts that the total particle number concentration (Ntot will decrease by 30–70% between 2008 and 2030. The number concentration of particles larger than 100 nm (N100, a proxy for cloud condensation nuclei (CCN concentration, is predicted to decrease by 40–70% during the same period. The predicted decrease in Ntot is mainly a result of reduced new particle formation due to the expected reduction in SO2 emissions, whereas the predicted decrease in N100 is a result of both decreasing condensational growth and reduced primary aerosol emissions. For larger emission reductions, PMCAMx-UF predicts reductions of 60–80% in both Ntot and N100 over Europe. Sensitivity tests reveal that a reduction in SO2 emissions is far more efficient than any other emission reduction investigated, in reducing Ntot. For N100, emission reductions of both SO2 and PM2.5 contribute significantly to the reduced concentration, even though SO2 plays the dominant role once more. The impact of SO2 for both new particle formation and growth over Europe may be expected to be somewhat higher during the simulated period with high photochemical activity than during times of the year with less incoming solar radiation. The predicted reductions in both Ntot and N100

  2. Sources and Dynamic Processes Controlling Background and Peak Concentrations of TGM in Nanjing, China

    Directory of Open Access Journals (Sweden)

    Casey B. Hall

    2014-03-01

    Full Text Available Total gaseous mercury (TGM data from urban Nanjing, at the western edge of the Yangtze River Delta (YRD region in China, over nine months, were analyzed for peak and background mercury concentrations. The background concentration of TGM was found to be 2.2 ng∙m−3. In examining episodic influences of free tropospheric air masses on the surface TGM concentrations in Nanjing, we hypothesize heterogeneity in the global distribution of TGM concentrations in the free troposphere. The nine-month averaged diurnal cycles of TGM indicate a strong co-emission with SO2 and an underestimation of greater than 80% TGM emissions in current inventories. Regular peak concentrations of mercury were investigated and the major causes were YRD emissions, transport from rural areas, and monsoonal transport. Transport of rural emissions is hypothesized to be from illegal artisanal small-scale gold mining that are currently missing in the emission inventories. Enhancement of TGM associated with summer monsoon contributed to a maximum TGM concentration in mid-May–early June, an inverse seasonality in comparison to most other observations in China, North America, and Europe.

  3. CMS/RPC background particle simulation with the GEANT code preliminary results

    CERN Document Server

    Jamil, M

    2005-01-01

    A method to simulate the background particles of compact muon solenoid (CMS) endcap resistive plate chambers (RPCs) is described using a realistic Monte Carlo simulation based on the geometry and tracking (GEANT) code and analyzed with physics analysis workstation (PAW) interfaces. Sensitivity calculations were performed for particles such as gamma 's, e/sup -/'s and e/sup +/'s in the range 0.1 - 100 MeV for their respective spectra. For the evaluation of the response of detector in the Large Hadron Collider (LHC) background environment, the gamma , e/sup -/ and e/sup +/ energy spectra expected in the CMS muon endcap region were taken into account whereas the RPC sensitivity was evaluated as a function of the detector size.

  4. Particle Acceleration in Kerr-(anti-) de Sitter Black Hole Backgrounds

    CERN Document Server

    Li, Yang; Li, Yun-Liang; Wei, Shao-Wen; Liu, Yu-Xiao

    2010-01-01

    Recently, Ban\\~{a}dos, Silk and West (BSW) found that the center-of-mass energy of two colliding test particles in the neighborhood of an extreme Kerr black hole could be arbitrarily high when one particle has the critical angular momentum. In their paper, they considered the black holes living in a Minkowski space-time with a zero cosmological constant. In this work, we study this process of particles in the backgrounds of the Kerr black holes living in a space-time with a nonzero cosmological constant. We find that for kerr black holes living in a space-time with a negative cosmological constant (Kerr-anti-de Sitter black holes), this process of particles could happen only if the Kerr-anti-de Sitter black hole is extreme and an additional fine tuning is satisfied; while for kerr black holes living in a space-time with a positive cosmological constant (Kerr-de Sitter black holes), this process of particles could happen no matter the Kerr-de Sitter black hole is extreme or not. We also study the particle coll...

  5. The characteristics of atmospheric CO2 concentration variation of four national background stations in China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Through the non-dispersive infrared method, flask sampling of atmospheric CO2 concen- tration was measured weekly at four national background stations including Waliguan, Shangdianzi, Lin’an, and Longfengshan. Based on the data collected from September 2006 to August 2007, along with the Waliguan station’s experience on in situ observational data processing, the selection methods for sampling data through the atmospheric background CO2 concentration analysis were preliminarily discussed. On the basis of this result, the variation features of the four typical regions’ atmospheric background CO2 concentration was analyzed for the first time. The results show that the atmospheric CO2 concentration at Waliguan, Shangdianzi, Lin’an, and Longfengshan is 383.5, 385.9, 387.8, and 384.3 ppm, respectively. During the research period, CO2 concentration at the Waliguan station changed slightly. However, the CO2 concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones, and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis. The results from this study can lay the foundation for more profound studies on atmospheric CO2 concentration level of different areas in China, and could be used to improve the understanding of carbon source and sink distribution.

  6. Anomalies in Natural Background Levels Associated with Minerals with Elevated Radionuclide Concentrations

    International Nuclear Information System (INIS)

    In the paper, the results of terrestrial natural background measurements in seven Chinese provinces are discussed. They have been generated as part of a mapping system based on sampling grids of 4 and 16 km2 to provide geochemical data for uranium, thorium and potassium, and complemented by gamma dose rate measurements 1 m above the ground. Points of elevated dose rates were identified as being due to human activities involving minerals with elevated activity concentrations. The number of these instances, and thus the general level of background radiation, is increasing. The result of the analysis indicates that control of activities involving such minerals needs to be considered. (author)

  7. Influence of target concentration and background binding on in vitro selection of affinity reagents.

    Directory of Open Access Journals (Sweden)

    Jinpeng Wang

    Full Text Available Nucleic acid-based aptamers possess many useful features that make them a promising alternative to antibodies and other affinity reagents, including well-established chemical synthesis, reversible folding, thermal stability and low cost. However, the selection process typically used to generate aptamers (SELEX often requires significant resources and can fail to yield aptamers with sufficient affinity and specificity. A number of seminal theoretical models and numerical simulations have been reported in the literature offering insights into experimental factors that govern the effectiveness of the selection process. Though useful, these previous models have not considered the full spectrum of experimental factors or the potential impact of tuning these parameters at each round over the course of a multi-round selection process. We have developed an improved mathematical model to address this important question, and report that both target concentration and the degree of non-specific background binding are critical determinants of SELEX efficiency. Although smaller target concentrations should theoretically offer superior selection outcome, we show that the level of background binding dramatically affect the target concentration that will yield maximum enrichment at each round of selection. Thus, our model enables experimentalists to determine appropriate target concentrations as a means for protocol optimization. Finally, we perform a comparative analysis of two different selection methods over multiple rounds of selection, and show that methods with inherently lower background binding offer dramatic advantages in selection efficiency.

  8. Decreasing particle number concentrations in a warming atmosphere and implications

    Directory of Open Access Journals (Sweden)

    F. Yu

    2012-03-01

    Full Text Available New particle formation contributes significantly to the number concentration of condensation nuclei (CN as well as cloud CN (CCN, a key factor determining aerosol indirect radiative forcing of the climate system. Using a physics-based nucleation mechanism that is consistent with a range of field observations of aerosol formation, it is shown that projected increases in global temperatures could significantly inhibit new particle, and CCN, formation rates worldwide. An analysis of CN concentrations observed at four NOAA ESRL/GMD baseline stations since the 1970s and two other sites since 1990s reveals long-term decreasing trends that are consistent in sign with, but are larger in magnitude than, the predicted temperature effects. The possible reasons for larger observed long-term CN reductions at remote sites are discussed. The combined effects of rising temperatures on aerosol nucleation rates and other chemical and microphysical processes may imply substantial decreases in future tropospheric particle abundances associated with global warming, delineating a potentially significant feedback mechanism that increases Earth's climate sensitivity to greenhouse gas emissions. Further research is needed to quantify the magnitude of such a feedback process.

  9. Decreasing particle number concentrations in a warming atmosphere and implications

    Directory of Open Access Journals (Sweden)

    F. Yu

    2011-10-01

    Full Text Available New particle formation contributes significantly to the number concentration of condensation nuclei (CN as well as cloud CN (CCN, a key factor determining aerosol indirect radiative forcing of the climate system. Using a physics-based nucleation mechanism that is consistent with a range of field observations of aerosol formation, it is shown that projected increases in global temperatures could significantly inhibit new particle, and CCN, formation rates worldwide. An analysis of CN concentrations observed at four NOAA ESRL/GMD baseline stations since the 1970s and two other sites since 1990s reveals long-term decreasing trends consistent with these predictions. The analysis also suggests, owing to larger observed CN reductions at remote sites than can be explained by the basic nucleation mechanism, that dimethylsulphide (DMS emissions may be decreasing worldwide with increasing global temperatures, implying a positive DMS-based cloud feedback forcing of the climate ("CLAW". The combined effects of rising temperatures on aerosol nucleation rates, and possibly on DMS emissions, may imply substantial decreases in future tropospheric particle abundances associated with global warming, delineating a potentially significant feedback mechanism that increases Earth's climate sensitivity to greenhouse gas emissions. Further research is needed to quantify the magnitude of such a feedback process.

  10. Pseudoclassical description of scalar particle in non-Abelian background and path-integral representations

    OpenAIRE

    Fresneda, R.; Gitman, D.

    2007-01-01

    Path-integral representations for a scalar particle propagator in non-Abelian external backgrounds are derived. To this aim, we generalize the procedure proposed by Gitman and Schvartsman 1993 of path-integral construction to any representation of SU(N) given in terms of antisymmetric generators. And for arbitrary representations of SU(N), we present an alternative construction by means of fermionic coherent states. From the path-integral representations we derive pseudoclassical actions for ...

  11. Particle currents on a CP violating Higgs background and the spontaneous baryogenesis mechanism

    International Nuclear Information System (INIS)

    We compute the particle currents induced on a bubble wall background at finite temperature in a model with CP violation in the Higgs sector. Using a field theory approach we show that fermionic currents arise at one loop, so that a suppression factor OMIKRON (htφ/πT)2 with respect to previous computations is found. The contributions to the Higgs currents are also derived and their relevancy for the spontaneous baryogenesis mechanism is discussed. (orig.)

  12. A magnetic diverter for charged particle background rejection in the SIMBOL-X telescope

    CERN Document Server

    Spiga, D; Bulgarelli, A; Dell'Orto, E; Foschini, L; Malaguti, G; Pareschi, G; Tagliaferri, G; Tiengo, A

    2015-01-01

    Minimization of charged particle background in X-ray telescopes is a well known issue. Charged particles (chiefly protons and electrons) naturally present in the cosmic environment constitute an important background source when they collide with the X-ray detector. Even worse, a serious degradation of spectroscopic performances of the X-ray detector was observed in Chandra and Newton-XMM, caused by soft protons with kinetic energies ranging between 100 keV and some MeV being collected by the grazing-incidence mirrors and funneled to the detector. For a focusing telescope like SIMBOL-X, the exposure of the soft X-ray detector to the proton flux can increase significantly the instrumental background, with a consequent loss of sensitivity. In the worst case, it can also seriously compromise the detector duration. A well-known countermeasure that can be adopted is the implementation of a properly-designed magnetic diverter, that should prevent high-energy particles from reaching the focal plane instruments of SIM...

  13. Does a nonzero tunneling probability imply particle production in time-independent classical electromagnetic backgrounds?

    International Nuclear Information System (INIS)

    In this paper, we probe the validity of the tunneling interpretation that is usually called forth in the literature to explain the phenomenon of particle production by time-independent classical electromagnetic backgrounds. We show that the imaginary part of the effective Lagrangian is zero for a complex scalar field quantized in a time-independent, but otherwise arbitrary, magnetic field. This result implies that no pair creation takes place in such a background. But we find that when the quantum field is decomposed into its normal modes in the presence of a spatially confined and time-independent magnetic field, there exists a nonzero tunneling probability for the effective Schroedinger equation. According to the tunneling interpretation, this result would imply that spatially confined magnetic fields can produce particles, thereby contradicting the result obtained from the effective Lagrangian. This lack of consistency between these two approaches calls into question the validity of attributing a nonzero tunneling probability for the effective Schroedinger equation to the production of particles by the time-independent electromagnetic backgrounds. The implications of our analysis are discussed. copyright 1996 The American Physical Society

  14. Environmentally relevant concentrations of microplastic particles influence larval fish ecology.

    Science.gov (United States)

    Lönnstedt, Oona M; Eklöv, Peter

    2016-06-01

    The widespread occurrence and accumulation of plastic waste in the environment have become a growing global concern over the past decade. Although some marine organisms have been shown to ingest plastic, few studies have investigated the ecological effects of plastic waste on animals. Here we show that exposure to environmentally relevant concentrations of microplastic polystyrene particles (90 micrometers) inhibits hatching, decreases growth rates, and alters feeding preferences and innate behaviors of European perch (Perca fluviatilis) larvae. Furthermore, individuals exposed to microplastics do not respond to olfactory threat cues, which greatly increases predator-induced mortality rates. Our results demonstrate that microplastic particles operate both chemically and physically on larval fish performance and development. PMID:27257256

  15. Giant In-Particle Field Concentration and Fano Resonances at Light Scattering by High-Refractive Index Particles

    CERN Document Server

    Tribelsky, M I

    2015-01-01

    A detailed analytical inspection of light scattering by a particle with high refractive index m+i\\kappa and small dissipative constant \\kappa is presented. We have shown that there is a dramatic difference in the behavior of the electromagnetic field within the particle (inner problem) and the scattered field outside it (outer problem). With an increase in m at fix values of the other parameters, the field within the particle asymptotically converges to a periodic function of m. The electric and magnetic type Mie resonances of different orders overlap substantially. It may lead to a giant concentration of the electromagnetic energy within the particle. At the same time, we demonstrate that identical transformations of the solution for the outer problem allow to present each partial scattered wave as a sum of two partitions. One of them corresponds to the m-independent wave, scattered by a perfectly reflecting particle and plays the role of a background, while the other is associated with the excitation of a s...

  16. Particle/vapor concentrations and distributions of PAHs in the atmosphere of southern Chesapeake Bay

    International Nuclear Information System (INIS)

    Atmospheric PAH concentrations were measured at four sites characterized as rural (Haven Beach), semiurban (York River), urban (Hampton), and industrialized (Elizabeth River) areas as part of a study to quantify gaseous exchange fluxes across the air-water interface of southern Chesapeake Bay. Aerosol particle-associated PAH concentrations were similar at all sites; however, PAH vapor concentrations in the urban areas were as much as a factor of 50 greater than those at the rural site. Mean total PAH concentrations ranged from 7.87 ng/m3 at the rural site to 92.8 ng/m3 at the urban site. Daily total PAH concentrations ranged from 1.60 to 198 ng/m3. Exponential increases in PAH vapor concentrations with temperature were observed at the non-rural sites, suggesting volatilization from contaminated surfaces during warmer weather; whereas PAH vapor concentrations at the rural Haven Beach site exhibited little seasonal variability. Aerosol particle-associated PAH levels were similar at all sites and increased in winter due to the temperature dependence of vapor-particle partitioning, increased sources from combustion of fossil fuel and wood for home heating, and cold condensation of source vapors to background aerosols as air masses are dispersed to remote regions. Plots of log Kd vs. log Psat,SC1 indicate PAH partitioning is not at equilibrium in rural areas of Southern Chesapeake Bay. In addition, plots of log Kd vs. 1/T for individual PAHs indicate difference particle characteristics or partitioning processes influence particle/vapor distributions at the urban and rural sites

  17. Origin of background electron concentration in InxGa1-xN alloys

    Science.gov (United States)

    Pantha, B. N.; Wang, H.; Khan, N.; Lin, J. Y.; Jiang, H. X.

    2011-08-01

    The origin of high background electron concentration (n) in InxGa1-xN alloys has been investigated. A shallow donor was identified as having an energy level (ED1) that decreases with x (ED1 = 16 meV at x = 0 and ED1 = 0 eV at x ˜ 0.5) and that crossover the conduction band at x ˜ 0.5. This shallow donor is believed to be the most probable cause of high n in InGaN. This understanding is consistent with the fact that n increases sharply with an increase in x and becomes constant for x > 0.5. A continuous reduction in n was obtained by increasing the V/III ratio during the epilayer growth, suggesting that nitrogen vacancy-related impurities are a potential cause of the shallow donors and high background electron concentration in InGaN.

  18. Particle dynamics during nanoparticle synthesis by laser ablation in a background gas

    Science.gov (United States)

    Nakata, Yoshiki; Muramoto, Junichi; Okada, Tatsuo; Maeda, Mitsuo

    2002-02-01

    Particle dynamics during Si nanoparticle synthesis in a laser-ablation plume in different background gases were investigated by laser-spectroscopic imaging techniques. Two-dimensional laser induced fluorescence and ultraviolet Rayleigh scattering techniques were used to visualize the spatial distribution of the Si atoms and nanoparticles grown, respectively. We have developed a visualization technique called re-decomposition laser-induced fluorescence to observe small nanoparticles (hereafter called clusters) which are difficult to observe by the conventional imaging techniques. In this article, the whole process of nanoparticle synthesis in different background gases of He, Ne, Ar, N2 and O2 was investigated by these techniques. In He, Ne, Ar and N2 background gases at 10 Torr, the clustering of the Si atoms started 200, 250, 300 and 800 μs after ablation, respectively. The growth rate of the clusters in He background gas was much larger than that in the other gases. The spatial distributions of the Si nanoparticles were mushroom like in He, N2 and O2, and column like in Ne and Ar. It is thought that the difference in distribution was caused by differences in the flow characteristics of the background gases, which would imply that the viscosity of the background gas is one of the main governing parameters.

  19. Assessment of exposure to respirable particles (PM2.5 concentrations in public transportation

    Directory of Open Access Journals (Sweden)

    M. Mohammadian

    2006-01-01

    Full Text Available Background and purpose: High concentrations of respirable particles may cause high incidence of respiratory diseases and mortality. Epidemiological exposure assessment is based on fixed site measurements in ambient air. However, major studies reported good relationship between indoor fine particulate air concentrations and personal exposure. This study is focussed on personal exposure to PM2.5 in different transportation modes and factors that cause high indoor PM2.5 levels.Materials and Methods: In this study, a calibrated real time monitor (MicroDust Pro was used to measure PM2.5 levels in 3 mode of transportation (bus, car and train on the same route. Results were also compared with PM10 concentrations measured by fixed site monitors. A small Poly Urethane Foam (PFU filter was designed for PM2.5 size fraction monitoring and a small personal sampling pump was used to provide a continuous airflow through the gravimetric adaptor and photo detector.Results: The mean PM2.5 concentration measured in the train was lower than the mean fixed site PM10 concentration. However, the mean PM2.5 levels in car and bus were much higher than those mean PM10 concentrations measured by fixed site monitors. Boarding, picking up, dropping off, and movement of passengers inside the bus and train were significantly related to short-term increases in PM2.5 concentrations. However, stopping at the traffic light was the most important factor associated with peak PM2.5 concentrations inside the car.Conclusion: Penetration of particles that were created by road traffic and resuspension of fine particles in the vehicles were the most important factors that may increase respirable particles in transportation modes.

  20. Receptor modelling of both particle composition and size distribution from a background site in London, UK

    Directory of Open Access Journals (Sweden)

    D. C. S. Beddows

    2015-04-01

    Full Text Available Positive Matrix Factorisation (PMF analysis was applied to PM10 chemical composition and particle Number Size Distribution (NSD data measured at an urban background site (North Kensington in London, UK for the whole of 2011 and 2012. The PMF analyses revealed six and four factors respectively which described seven sources or aerosol types. These included Nucleation, Traffic, Diffuse Urban, Secondary, Fuel Oil, Marine and Non-Exhaust/Crustal sources. Diffuse Urban, Secondary and Traffic sources were identified by both the chemical composition and particle number size distribution analysis, but a Nucleation source was identified only from the particle Number Size Distribution dataset. Analysis of the PM10 chemical composition dataset revealed Fuel Oil, Marine, Non-Exhaust Traffic/Crustal sources which were not identified from the number size distribution data. The two methods appear to be complementary, as the analysis of the PM10 chemical composition data is able to distinguish components contributing largely to particle mass whereas the number particle size distribution dataset is more effective for identifying components making an appreciable contribution to particle number. Analysis was also conducted on the combined chemical composition and number size distribution dataset revealing five factors representing Diffuse Urban, Nucleation, Secondary, Aged Marine and Traffic sources. However, the combined analysis appears not to offer any additional power to discriminate sources above that of the aggregate of the two separate PMF analyses. Day-of-the-week and month-of-the-year associations of the factors proved consistent with their assignment to source categories, and bivariate polar plots which examined the wind directional and wind speed association of the different factors also proved highly consistent with their inferred sources.

  1. Transit time of a freely-falling quantum particle in a background gravitational field

    CERN Document Server

    Davies, Paul Charles William

    2004-01-01

    Using a model quantum clock, I evaluate an expression for the time of a non-relativistic quantum particle to transit a piecewise geodesic path in a background gravitational field with small spacetime curvature (gravity gradient), in the case that the apparatus is in free fall. This calculation complements and extends an earlier one (Davies 2004) in which the apparatus is fixed to the surface of the Earth. The result confirms that, for particle velocities not too low, the quantum and classical transit times coincide, in conformity with the principle of equivalence. I also calculate the quantum corrections to the transit time when the de Broglie wavelengths are long enough to probe the spacetime curvature. The results are compared with the calculation of Chaio and Speliotopoulos (2003), who propose an experiment to measure the foregoing effects.

  2. Transit time of a freely falling quantum particle in a background gravitational field

    International Nuclear Information System (INIS)

    Using a model quantum clock, I evaluate an expression for the time of a non-relativistic quantum particle to transit a piecewise geodesic path in a background gravitational field with small spacetime curvature (gravity gradient), in the case in which the apparatus is in free fall. This calculation complements and extends an earlier one (Davies 2004) in which the apparatus is fixed to the surface of the Earth. The result confirms that, for particle velocities not too low, the quantum and classical transit times coincide, in conformity with the principle of equivalence. I also calculate the quantum corrections to the transit time when the de Broglie wavelengths are long enough to probe the spacetime curvature. The results are compared with the calculation of Chiao and Speliotopoulos (2003), who propose an experiment to measure the foregoing effects

  3. Interaction of a circularly polarised gravitational wave with a charged particle in a static magnetic background

    CERN Document Server

    Gangopadhyay, Sunandan; Saha, Swarup

    2014-01-01

    Interaction of a charged particle in a static magnetic background, i.e., a Landau system with circularly polarised gravitational wave (GW) is studied quantum mechanically in the long wavelength and low velocity limit. We quantize the classical Hamiltonian following \\cite{speli}. The rotating polarization vectors of the circularly polarized GW are employed to form a unique directional triad which served as the coordinate axes. The Schrodinger equations for the system are cast in the form of a set of coupled linear differential equations. This system is solved by iterative technique. We compute the time-evolution of the position and momentum expectation values of the particle. The results show that the resonance behaviour obtained earlier\\cite{emgw_classical} by classical treatements of the system has a quantum analogue not only for the linearly polarized GW \\cite{emgw_1_lin}, but for circularly polarized GW as well.

  4. Thermodynamic properties of neutral particle in presence of Topological defects in Magnetic Cosmic String Background

    CERN Document Server

    Hassanabadi, Hassan

    2016-01-01

    In this paper, we study the covariant form of the non-relativistic Schrodinger-Pauli equation in the space-time generated by a cosmic string and discuss the solutions of this equation in present of interaction between the magnetic dipole momentum and electromagnetic field. We study the influence of the topology on this system. We obtain the solution of radial part as well as the energy levels. We consider all thermodynamic properties of neutral particle in magnetic cosmic string background by using an approach based on the partition function method.

  5. Estimation of background carrier concentration in fully depleted GaN films

    Science.gov (United States)

    Chandrasekar, Hareesh; Singh, Manikant; Raghavan, Srinivasan; Bhat, Navakanta

    2015-11-01

    Buffer leakage is an important parasitic loss mechanism in AlGaN/GaN high electron mobility transistors (HEMTs) and hence various methods are employed to grow semi-insulating buffer layers. Quantification of carrier concentration in such buffers using conventional capacitance based profiling techniques is challenging due to their fully depleted nature even at zero bias voltages. We provide a simple and effective model to extract carrier concentrations in fully depleted GaN films using capacitance-voltage (C-V) measurements. Extensive mercury probe C-V profiling has been performed on GaN films of differing thicknesses and doping levels in order to validate this model. Carrier concentrations as extracted from both the conventional C-V technique for partially depleted films having the same doping concentration, and Hall measurements show excellent agreement with those predicted by the proposed model thus establishing the utility of this technique. This model can be readily extended to estimate background carrier concentrations from the depletion region capacitances of HEMT structures and fully depleted films of any class of semiconductor materials.

  6. Subway construction activity influence on polycyclic aromatic hydrocarbons in fine particles: Comparison with a background mountainous site

    Science.gov (United States)

    Kong, Shaofei; Li, Xuxu; Li, Qi; Yin, Yan; Li, Li; Chen, Kui; Liu, Dantong; Yuan, Liang; Pang, Xiaobing

    2015-07-01

    Intensive construction activities worsened the surrounding atmospheric environment in China. Eighteen polycyclic aromatic hydrocarbons (PAHs) in fine particles (PM2.5) were collected at a subway construction site (SC) of Nanjing and compared with a regional background mountainous site (BM) to examine the influence of anthropogenic activities on concentrations, sources and health risks of PAHs. Average PAH concentrations at SC were higher than BM at a factor of about 5.9. All PAH species at SC were higher than BM, with the SC/BM ratios ranging from 1.3 (NaP) to 10.3 (BaP). PAH profiles differed for the two sites. The SC site had higher mass fractions of PAHs from coal combustion and vehicle emission, while the BM site held higher mass percentages of PAHs from long-range transported wood combustion and industrial activities. Lower temperature at BM may lead to the higher mass percentages of low ring PAHs. Coal combustion, traffic emissions and biomass burning were the common sources for PAHs at both SC and BM. Construction workers were exposed to higher BaPeq concentrations, nearly ten times of the background site and their lifetime cancer risk reached to 0.6 per 1,000,000 exposed worker, owing to the influence of coal combustion, vehicle emission and industrial activities at the surroundings of SC.

  7. Regional background aerosols over the Balearic Islands over the last 3 years: ground-based concentrations, atmospheric deposition and sources

    Science.gov (United States)

    Cerro, Jose Carlos; Pey, Jorge; Bujosa, Carles; Caballero, Sandra; Alastuey, Andres; Sicard, Michael; Artiñano, Begoña; Querol, Xavier

    2013-04-01

    In the context of the ChArMEx (The Chemistry-Aerosol Mediterranean Experiment, https://charmex.lsce.ipsl.fr) initiative, a 3-year study over a regional background environment (Can Llompart, CLP) in Mallorca has been conducted. Ground-based PM mass concentrations, gaseous pollutants and meteorological parameters were continuously registered from 2010 to 2012. Since the beginning of the campaign, PM10 daily samples for chemical determinations were obtained every 4 days, and dry and wet deposition samples were collected every week. Moreover, additional instruments (condensation particle counter, multi-angle absorption photometer, airpointer, sequential high and low volume samplers) were deployed during intensive filed campaigns in 2011 and 2012, as well as the sampling frequency was intensified. In the laboratory, PM samples were analyzed for inorganic compounds, and organic and elemental carbon following different approaches. In addition, n-alkanes, iso-alkanes, antiso-alkanes, levoglucosan, alkanoic acids and cholesterol were determined by GC-MS chromatography in a selection of 30 samples. Mean PM10, PM2.5 and PM1 concentrations in the period 2010-2012 reached 17, 11, and 8 µg/m3 respectively. Mass concentrations displayed marked seasonal trends, with much higher background levels in summer due to stagnant conditions over the western Mediterranean and increased frequency of Saharan dust events. Likewise, diverse-intensity peaks of coarse PM due to African dust inputs were observed along the year. On average, African dust in PM10 accounted for 1.0-1.5 µg/m3. Sporadic pollution events, characterized by most of the particles in the fine mode, were related to the transport of anthropogenic polluted air masses from central and eastern Europe. Wet and dry atmospheric deposition samples are being analyzed to quantify the deposition fluxes for different soluble and insoluble compounds. On average, PM10 composition is made up of organic matter (23%), mineral components (17

  8. Estimation of background CO2 concentrations at the high alpine station Schneefernerhaus by atmospheric observations and inverse modelling

    Science.gov (United States)

    Giemsa, Esther; Jacobeit, Jucundus; Ries, Ludwig; Frank, Gabriele; Hachinger, Stephan; Meyer-Arnek, Julian

    2016-04-01

    In order to estimate the influence of Central European CO2 emissions, a new method to retrieve background concentrations based on statistics of radon-222 and backward trajectories is developed and applied to the CO2 observations at the alpine high-altitude research station Schneefernerhaus (2670 m a.s.l.). The reliable identification of baseline conditions is important for perceiving changes in time as well as in the sources and sinks of greenhouse gases and thereby assessing the efficiency of existing mitigation strategies. In the particular case of Central Europe, the analysis of background concentrations could add further insights on the question why background CO2 concentrations increased in the last few decades, despite a significant decrease in the reported emissions. Ongoing effort to define the baseline conditions has led to a variety of data selection techniques. In this diversity of data filtering concepts, a relatively recent data selection method effectively appropriates observations of radon-222 to reliably and unambiguously identify baseline air masses. Owing to its relatively constant emission rate from the ice-free land surface and its half-life of 3.8 days that is solely achieved through radioactive decay, the tropospheric background concentration of the inert radioactive gas is low and temporal variations caused by changes in atmospheric transport are precisely detectable. For defining the baseline air masses reaching the high alpine research station Schneefernerhaus, an objective analysis approach is applied to the two-hourly radon records. The CO2 values of days by the radon method associated with prevailing atmospheric background conditions result in the CO2 concentrations representing the least land influenced air masses. Additionally, three-dimensional back-trajectories were retrieved using the Lagrangian Particle Dispersion Model (LPDM) FLEXPART driven by analysis fields of the Global Forecast System (GFS) produced by the National Centers

  9. Establishing policy relevant background (PRB) ozone concentrations in the United States.

    Science.gov (United States)

    McDonald-Buller, Elena C; Allen, David T; Brown, Nancy; Jacob, Daniel J; Jaffe, Daniel; Kolb, Charles E; Lefohn, Allen S; Oltmans, Samuel; Parrish, David D; Yarwood, Greg; Zhang, Lin

    2011-11-15

    Policy Relevant Background (PRB) ozone concentrations are defined by the United States (U.S.) Environmental Protection Agency (EPA) as those concentrations that would occur in the U.S. in the absence of anthropogenic emissions in continental North America (i.e., the U.S, Canada, and Mexico). Estimates of PRB ozone have had an important role historically in the EPA's human health and welfare risk analyses used in establishing National Ambient Air Quality Standards (NAAQS). The margin of safety for the protection of public health in the ozone rulemaking process has been established from human health risks calculated based on PRB ozone estimates. Sensitivity analyses conducted by the EPA have illustrated that changing estimates of PRB ozone concentrations have a progressively greater impact on estimates of mortality risk as more stringent standards are considered. As defined by the EPA, PRB ozone is a model construct, but it is informed by measurements at relatively remote monitoring sites (RRMS). This review examines the current understanding of PRB ozone, based on both model predictions and measurements at RRMS, and provides recommendations for improving the definition and determination of PRB ozone.

  10. Seasonal Variations of Number Size Distributions and Mass Concentrations of Atmospheric Particles in Beijing

    Institute of Scientific and Technical Information of China (English)

    YU Jianhua; Benjamin GUINOT; YU Tong; WANG Xin; LIU Wenqing

    2005-01-01

    Particle number and mass concentrations were measured in Beijing during the winter and summer periods in 2003, together with some other parameters including black carbon (BC) and meteorological conditions. Particle mass concentrations exhibited low seasonality, and the ratio of PM2.5/PM10 in winter was higher than that in summer. Particle number size distribution (PSD) was characterized by four modes and exhibited low seasonality. BC was well correlated with the number and mass concentrations of accumulation and coarse particles, indicating these size particles are related to anthropogenic activities.Particle mass and number concentrations (except ultra-fine and nucleation particles) followed well the trends of BC concentration for the majority of the day, indicating that most particles were associated with primary emissions. The diurnal number distributions of accumulation and coarse mode particles were characterized by two peaks.

  11. Searching for concentric low variance circles in the cosmic microwave background

    Science.gov (United States)

    DeAbreu, Adam; Contreras, Dagoberto; Scott, Douglas

    2015-12-01

    In a recent paper, Gurzadyan & Penrose claim to have found directions in the sky around which there are multiple concentric sets of annuli with anomalously low variance in the cosmic microwave background (CMB). These features are presented as evidence for a particular theory of the pre-Big Bang Universe. We are able to reproduce the analysis these authors presented for data from the WMAP satellite and we confirm the existence of these apparently special directions in the newer Planck data. However, we also find that these features are present at the same level of abundance in simulated Gaussian CMB skies, i.e., they are entirely consistent with the predictions of the standard cosmological model.

  12. Searching for concentric low variance circles in the cosmic microwave background

    CERN Document Server

    DeAbreu, Adam; Scott, Douglas

    2015-01-01

    In a recent paper, Gurzadyan & Penrose claim to have found directions in the sky around which there are multiple concentric sets of annuli with anomalously low variance in the cosmic microwave background (CMB). These features are presented as evidence for a particular theory of the pre-Big Bang Universe. We are able to reproduce the analysis these authors presented for data from the WMAP satellite and we confirm the existence of these apparently special directions in the newer Planck data. However, we also find that these features are present at the same level of abundance in simulated Gaussian CMB skies, i.e. they are entirely consistent with the predictions of the standard cosmological model.

  13. Determination of background concentrations of hydrochemical parameters and water quality assessment in the Akhuryan River Basin (Armenia)

    Science.gov (United States)

    Arpine, Hovhannisyan; Gayane, Shahnazaryan

    2016-08-01

    The determination of background values of hydrochemical parameters, to distinguish between natural concentration and anthropogenically-influenced concentrations, is highly relevant. In presented study, to estimate the background values of hydrochemical parameters in Akhuryan River Basin, log-normal probability functions on the hydrochemical parameters concentrations was applied. The study is carried out on the basis of hydrochemical data of surface water quality monitoring for the period of 2010-2013. This study highlights the usefulness of application of site-specific background concentrations for the evaluation, interpretation of surface water quality and for determination of pollution sources.

  14. Interaction of a circularly polarised gravitational wave with a charged particle in a static magnetic background

    Science.gov (United States)

    Gangopadhyay, Sunandan; Saha, Anirban; Saha, Swarup

    2015-06-01

    Interaction of a charged particle in a static magnetic background, i.e., a Landau system with circularly polarised gravitational wave (GW) is studied quantum mechanically in the long wavelength and low velocity limit. We quantize the classical Hamiltonian following (Speliotopoulos in Phys Rev D 51:1701, 1995). The rotating polarization vectors of the circularly polarized GW are employed to form a unique directional triad which served as the coordinate axes. The Schrodinger equations for the system are cast in the form of a set of coupled linear differential equations. This system is solved by iterative technique. We compute the time-evolution of the position and momentum expectation values of the particle. The results show that the resonance behaviour obtained earlier (Macedo and Nelson in Astrophys J 362:584, 1990; Papadopoulos in Astron Astrophys 396:1045, 2002) by classical treatements of the system has a quantum analogue not only for the linearly polarized GW (Gangopadhyay and Saha in Mod Phys Lett A 27:1250192, 2012), but for circularly polarized GW as well.

  15. Guarded capacitance probes for measuring particle concentration and flow

    Science.gov (United States)

    Louge, Michel Y.

    1995-01-01

    Guarded capacitance probe structures are constructed with guard electrodes surrounding one or more sensor electrodes and ground electrodes or grounded surfaces surrounding the guard electrodes. In a one sensor embodiment, the probe utilizes an apertured sensor electrode and the guard electrode both surrounds the sensor electrode and fills the aperture. This embodiment is particularly useful for measuring particle concentration in a fluid suspension contained within a vessel or pipe. The portion of the guard electrode within the aperture of the sensor electrode prevents electric field lines from emanating from the sensor electrode into the fluid suspension and toward infinity. A two sensor embodiment of the probe is useful for measuring flow velocities of fluid suspensions through cross correlation of the outputs generated by each sensor. The relative dimensions of the guard and sensor electrodes are selected to provide the most accurate measurements by confining the electric lines emanating from the sensor electrode or electrodes and terminating on the surrounding grounded surfaces to a small measurement volume of the fluid suspension near the vessel or pipe wall.

  16. Concentrations of radionuclides in cassava growing in high background radiation area and their transfer

    International Nuclear Information System (INIS)

    The concentrations of several natural radionuclides in common cassava (Manihot esculenta Crantz) growing in Yangjiang County, a high background radiation area in Guangdong Province, and their uptake from soil and distribution in the plant were investigated. The results show that the concentrations of natural uranium and thorium in cassava root are of the order of 10-6 g/kg, and those of radium-226, radium-228, lead-210 and polonium-210 are of the order of 10-11 Ci/kg. The highest level is 9.30 +- 0.30 x 10-11 Ci/kg (lead-210), and the lowest is 3.99 +- 0.20 x 10-11 Ci/kg (radium-226). The levels of natural uranium, thorium, radium-226 and polonium-210 in cassava are below the limits stipulated by the regulations for food hygiene in China, while the lead-210 level approaches the limit. It is noticeable that the highest level of radium-228 is 7.28 +- 1.03 x 10-11 Ci/kg, 10.4 times higher than the limit. The transfer of all he nuclides from soil to different parts of cassava shows a pattern contrary to that of he nuclides in the other regions where uranium-and radium-containing waste water and phosphate fertilizer are used in agriculture

  17. Characterization of Semi-volatility of Atmospheric Submicron Particles at a Regional Background Site in North China

    Science.gov (United States)

    He, L. Y.

    2015-12-01

    HE Lingyan1, HUANG Congni1, HUANG Xiaofeng11. Key Laboratory for Urban Habitat Environmental Science and Technology, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China Abstract:The coupling of a Thermal Denuder (TD) with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was used in Xianghe, which is a regional background site in North China, during June - July, 2013 to on-line measure the mass concentrations and semi-volatilities of atmospheric submicron particles, including organic matter (OM), SO42- , NO3-, NH4+, and Cl-. The total PM1 mass concentration measured was averagely (47.9±47.3) mg/m3 during the campaign, with OM accounting for 38.2% of the total PM1 mass, followed by SO42- (33.7%), NH4+ (13.8%), NO3- (12.3%), and Cl- (2.0%). It was found that NO3- and Cl- had the highest semi-volatility, with about 60% of them evaporating into the gas phase by increasing the temperature to 50 °C, while SO42- showed the lowest semi-volatility, with almost 90% of its mass remaining in the particle phase at 50 °C. The semi-volatility of OM and NH4+ was at the middle level. The semi-volatility of NO3- was affected by the pollution level of the atmospheric submicron particles since it showed an increasing trend with the increasing of PM1 at 50 °C. The oxygen-to-carbon ration of organic aerosol was 0.47 to 0.60 by increasing the temperature from 50 ℃ to 200 °C. In addition, the semi-volatility of the PM1 species with vacuum aerodynamic diameters of 60-2000 nm was little size dependent. The calculation based on the high-resolution mass spectra of OM showed that CO2+-containing organic species had lower semi-volatility, while C4H9+-containing organic species had higher semi-volatility. The semi-volatility of OM was found to be negatively related to its oxidation state. The quantitative result of atmospheric submicron particles' semi-volatility is essential to the research of the physicochemical

  18. Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma

    International Nuclear Information System (INIS)

    Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating

  19. Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kaganovich, I.D.; Davidson, R.C.; Dorf, M.A.; Startsev, E.A.; Sefkow, A.B; Friedman, A.F.; Lee, E.P.

    2009-09-03

    Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating

  20. Background concentrations and reference values for heavy metals in soils of Cuba.

    Science.gov (United States)

    Alfaro, Mirelys Rodríguez; Montero, Alfredo; Ugarte, Olegario Muñiz; do Nascimento, Clístenes Williams Araújo; de Aguiar Accioly, Adriana Maria; Biondi, Caroline Miranda; da Silva, Ygor Jacques Agra Bezerra

    2015-01-01

    The potential threat of heavy metals to human health has led to many studies on permissible levels of these elements in soils. The objective of this study was to establish quality reference values (QRVs) for Cd, Pb, Zn, Cu, Ni, Cr, Fe, Mn, As, Hg, V, Ba, Sb, Ag, Co, and Mo in soils of Cuba. Geochemical associations between trace elements and Fe were also studied, aiming to provide an index for establishing background concentrations of metals in soils. Surface samples of 33 soil profiles from areas of native forest or minimal anthropic influence were collected. Samples were digested (USEPA method 3051A), and the metals were determined by ICP-OES. The natural concentrations of metals in soils of Cuba followed the order Fe > Mn > Ni > Cr > Ba > V > Zn > Cu > Pb > Co > As > Sb > Ag > Cd > Mo > Hg. The QRVs found for Cuban soils were as follows (mg kg(-1)): Ag (1), Ba (111), Cd (0.6), Co (25), Cr (153), Cu (83), Fe (54,055), Mn (1947), Ni (170), Pb (50), Sb (6), V (137), Zn (86), Mo (0.1), As (19), and Hg (0.1). The average natural levels of heavy metals are above the global average, especially for Ni and Cr. The chemical fractionation of soil samples presenting anomalous concentrations of metals showed that Cu, Ni, Cr, Sb, and As have low bioavailability. This suggests that the risk of contamination of agricultural products via plant uptake is low. However, the final decision on the establishment of soil QRVs in Cuba depends on political, economic, and social issues and in-depth risk analyses considering all routes of exposure to these elements.

  1. Increasing surface ozone concentrations in the background atmosphere of Southern China, 1994-2007

    Science.gov (United States)

    Wang, T.; Wei, X. L.; Ding, A. J.; Poon, C. N.; Lam, K. S.; Li, Y. S.; Chan, L. Y.; Anson, M.

    2009-08-01

    Tropospheric ozone is of great importance with regard to air quality, atmospheric chemistry, and climate change. In this paper we report the first continuous record of surface ozone in the background atmosphere of South China. The data were obtained from 1994 to 2007 at a coastal site in Hong Kong, which is strongly influenced by the outflow of Asian continental air during the winter and the inflow of maritime air from the subtropics in the summer. Three methods are used to derive the rate of change in ozone. A linear fit to the 14-year record shows that the ozone concentration increased by 0.58 ppbv/yr, whereas comparing means in years 1994-2000 and 2001-2007 gives an increase of 0.87 ppbv/yr for a 7-year period. The ozone changes in air masses from various source regions are also examined. Using local wind and carbon monoxide (CO) data to filter out local influence, we find that ozone increased by 0.94 ppbv/yr from 1994-2000 to 2001-2007 in air masses from Eastern China, with similar changes in the other two continent-influenced air-mass groups, but no statistically significant change in the marine air. An examination of the nitrogen dioxide (NO2) column obtained from GOME and SCIAMACHY reveals an increase in atmospheric NO2 in China's three fastest developing coastal regions, whereas NO2 in other parts of Asia decreased during the same period, and no obvious trend over the main shipping routes in the South China Sea was indicated. Thus the observed increase in background ozone in Hong Kong is most likely due to the increased emissions of NO2 (and possibly volatile organic compounds (VOCs) as well) in the upwind coastal regions of mainland China. The CO data at Hok Tsui showed less definitive changes compared to the satellite NO2 column. The increase in background ozone likely made a strong contribution (81%) to the rate of increase in "total ozone" at an urban site in Hong Kong, suggesting the need to consider distant sources when developing long-term strategies

  2. Source appointment of fine particle number and volume concentration during severe haze pollution in Beijing in January 2013.

    Science.gov (United States)

    Liu, Zirui; Wang, Yuesi; Hu, Bo; Ji, Dongsheng; Zhang, Junke; Wu, Fangkun; Wan, Xin; Wang, Yonghong

    2016-04-01

    Extreme haze episodes repeatedly shrouded Beijing during the winter of 2012-2013, causing major environmental and health problems. To better understand these extreme events, particle number size distribution (PNSD) and particle chemical composition (PCC) data collected in an intensive winter campaign in an urban site of Beijing were used to investigate the sources of ambient fine particles. Positive matrix factorization (PMF) analysis resolved a total of eight factors: two traffic factors, combustion factors, secondary aerosol, two accumulation mode aerosol factors, road dust, and long-range transported (LRT) dust. Traffic emissions (54%) and combustion aerosol (27%) were found to be the most important sources for particle number concentration, whereas combustion aerosol (33%) and accumulation mode aerosol (37%) dominated particle volume concentrations. Chemical compositions and sources of fine particles changed dynamically in the haze episodes. An enhanced role of secondary inorganic species was observed in the formation of haze pollution. Regional transport played an important role for high particles, contribution of which was on average up to 24-49% during the haze episodes. Secondary aerosols from urban background presented the largest contributions (45%) for the rapid increase of fine particles in the severest haze episode. In addition, the invasion of LRT dust aerosols further elevated the fine particles during the extreme haze episode. Our results showed a clear impact of regional transport on the local air pollution, suggesting the importance of regional-scale emission control measures in the local air quality management of Beijing.

  3. Trichloromethyl compounds--natural background concentrations and fates within and below coniferous forests.

    Science.gov (United States)

    Albers, Christian Nyrop; Hansen, Poul Erik; Jacobsen, Ole Stig

    2010-11-15

    Pollution with organochlorines has received major attention due to various environmental effects, but it is now increasingly recognized, that they also take part in biogeochemical cycles and that natural background concentrations exist for several chlorinated compounds. We here report the natural occurrence and cycling of organic compounds with a trichloromethyl moiety in common. The study areas are temperate coniferous forests. Trichloromethyl compounds can be found in all compartments of the forests (groundwater, soil, vegetation and throughfall), but not all compounds in all compartments. The atmospheric input of trichloromethyl compounds is found to be minor, with significant contributions for trichloroacetic acid (TCAA), only. In top soil, where the formation of the compounds is expected to occur, there is a clear positive relationship between chloroform and trichloroacetyl containing compounds. Other positive relations occur, which in combination with chlorination experiments performed in the laboratory, point to the fact that all the trichloromethyl compounds may be formed concurrently in the soil, and their subsequent fates then differ due to different physical, chemical and biological properties. TCAA cannot be detected in soil and groundwater, but sorption and mineralization experiments performed in the laboratory in combination with analyses of vegetation, show that TCAA is probably formed in the top soil and then partly taken up by the vegetation and partly mineralized in the soil. Based on this and previous studies, a conceptual model for the natural cycling of trichloromethyl compounds in forests is proposed.

  4. Core-shell hydrogel particles harvest, concentrate and preserve labile low abundance biomarkers.

    Directory of Open Access Journals (Sweden)

    Caterina Longo

    Full Text Available BACKGROUND: The blood proteome is thought to represent a rich source of biomarkers for early stage disease detection. Nevertheless, three major challenges have hindered biomarker discovery: a candidate biomarkers exist at extremely low concentrations in blood; b high abundance resident proteins such as albumin mask the rare biomarkers; c biomarkers are rapidly degraded by endogenous and exogenous proteinases. METHODOLOGY AND PRINCIPAL FINDINGS: Hydrogel nanoparticles created with a N-isopropylacrylamide based core (365 nm-shell (167 nm and functionalized with a charged based bait (acrylic acid were studied as a technology for addressing all these biomarker discovery problems, in one step, in solution. These harvesting core-shell nanoparticles are designed to simultaneously conduct size exclusion and affinity chromatography in solution. Platelet derived growth factor (PDGF, a clinically relevant, highly labile, and very low abundance biomarker, was chosen as a model. PDGF, spiked in human serum, was completely sequestered from its carrier protein albumin, concentrated, and fully preserved, within minutes by the particles. Particle sequestered PDGF was fully protected from exogenously added tryptic degradation. When the nanoparticles were added to a 1 mL dilute solution of PDGF at non detectable levels (less than 20 picograms per mL the concentration of the PDGF released from the polymeric matrix of the particles increased within the detection range of ELISA and mass spectrometry. Beyond PDGF, the sequestration and protection from degradation for a series of additional very low abundance and very labile cytokines were verified. CONCLUSIONS AND SIGNIFICANCE: We envision the application of harvesting core-shell nanoparticles to whole blood for concentration and immediate preservation of low abundance and labile analytes at the time of venipuncture.

  5. The ultralow radioisotope concentration measurements in different samples with the underground low-background gamma-spectrometer

    International Nuclear Information System (INIS)

    The method is described of measurement and calculation of the ultralow radioisotope concentrations in the different samples with the low background gamma-spectrometer placed in an underground chamber at a depth of 660 m w.e.. (author)

  6. A Method for Estimating Urban Background Concentrations in Support of Hybrid Air Pollution Modeling for Environmental Health Studies

    Directory of Open Access Journals (Sweden)

    Saravanan Arunachalam

    2014-10-01

    Full Text Available Exposure studies rely on detailed characterization of air quality, either from sparsely located routine ambient monitors or from central monitoring sites that may lack spatial representativeness. Alternatively, some studies use models of various complexities to characterize local-scale air quality, but often with poor representation of background concentrations. A hybrid approach that addresses this drawback combines a regional-scale model to provide background concentrations and a local-scale model to assess impacts of local sources. However, this approach may double-count sources in the study regions. To address these limitations, we carefully define the background concentration as the concentration that would be measured if local sources were not present, and to estimate these background concentrations we developed a novel technique that combines space-time ordinary kriging (STOK of observations with outputs from a detailed chemistry-transport model with local sources zeroed out. We applied this technique to support an exposure study in Detroit, Michigan, for several pollutants (including NOx and PM2.5, and evaluated the estimated hybrid concentrations (calculated by combining the background estimates that addresses this issue of double counting with local-scale dispersion model estimates using observations. Our results demonstrate the strength of this approach specifically by eliminating the problem of double-counting reported in previous hybrid modeling approaches leading to improved estimates of background concentrations, and further highlight the relative importance of NOx vs. PM2.5 in their relative contributions to total concentrations. While a key limitation of this approach is the requirement for another detailed model simulation to avoid double-counting, STOK improves the overall characterization of background concentrations at very fine spatial scales.

  7. A Method for Estimating Urban Background Concentrations in Support of Hybrid Air Pollution Modeling for Environmental Health Studies

    Science.gov (United States)

    Arunachalam, Saravanan; Valencia, Alejandro; Akita, Yasuyuki; Serre, Marc L.; Omary, Mohammad; Garcia, Valerie; Isakov, Vlad

    2014-01-01

    Exposure studies rely on detailed characterization of air quality, either from sparsely located routine ambient monitors or from central monitoring sites that may lack spatial representativeness. Alternatively, some studies use models of various complexities to characterize local-scale air quality, but often with poor representation of background concentrations. A hybrid approach that addresses this drawback combines a regional-scale model to provide background concentrations and a local-scale model to assess impacts of local sources. However, this approach may double-count sources in the study regions. To address these limitations, we carefully define the background concentration as the concentration that would be measured if local sources were not present, and to estimate these background concentrations we developed a novel technique that combines space-time ordinary kriging (STOK) of observations with outputs from a detailed chemistry-transport model with local sources zeroed out. We applied this technique to support an exposure study in Detroit, Michigan, for several pollutants (including NOx and PM2.5), and evaluated the estimated hybrid concentrations (calculated by combining the background estimates that addresses this issue of double counting with local-scale dispersion model estimates) using observations. Our results demonstrate the strength of this approach specifically by eliminating the problem of double-counting reported in previous hybrid modeling approaches leading to improved estimates of background concentrations, and further highlight the relative importance of NOx vs. PM2.5 in their relative contributions to total concentrations. While a key limitation of this approach is the requirement for another detailed model simulation to avoid double-counting, STOK improves the overall characterization of background concentrations at very fine spatial scales. PMID:25321872

  8. The effect of dust emissions from open storage piles to particle ambient concentration and human exposure.

    Science.gov (United States)

    Chalvatzaki, E; Aleksandropoulou, V; Glytsos, T; Lazaridis, M

    2012-12-01

    The current study focus on the determination of dust emissions from piles in open storage yards of a municipal solid waste (MSW) composting site and the subsequent atmospheric dust dispersion. The ISC3-ST (Industrial Source Complex Version 3 - Short Term) model was used for the evaluation of the PM(10) ambient concentrations associated with the dispersion of MSW compost dust emissions in air. Dust emission rates were calculated using the United States Environmental Protection Agency proposed dust resuspension formulation from open storage piles using local meteorological data. The dispersion modelling results on the spatial distribution of PM(10) source depletion showed that the maximum concentrations were observed at a distance 25-75 m downwind of the piles in the prevailing wind direction. Sensitivity calculations were performed also to reveal the effect of the compost pile height, the friction velocity and the receptor height on the ambient PM(10) concentration. It was observed that PM(10) concentrations (downwind in the prevailing wind direction) increased with increasing the friction velocity, increasing the pile height (for distances greater than 125 m from the source) and decreasing the receptor height (for distances greater than 125 m from the source). Furthermore, the results of ISC3-ST were analysed with the ExDoM (Exposure Dose Model) human exposure model. The ExDoM is a model for calculating the human exposure and the deposition dose, clearance, and finally retention of aerosol particles in the human respiratory tract (RT). PM(10) concentration at the composting site was calculated as the sum of the concentration from compost pile dust resuspension and the background concentration. It was found that the exposure to PM(10) and deposited lung dose for an adult Caucasian male who is not working at the composting site is less by 20-74% and 29-84%, respectively, compared to those for a worker exposed to PM concentrations at the composting site.

  9. Micro-scale variability of urban particle number and mass concentrations in Leipzig, Germany

    Directory of Open Access Journals (Sweden)

    Wolfram Birmili

    2013-04-01

    Full Text Available We investigated the micro-scale variability of particle number and mass concentrations in the urban atmosphere of Leipzig, Germany. Particles were sampled in May and June 2011 using portable instrumentation along a fixed measurement route, representing different degrees of outdoor particle exposure that can be experienced by a pedestrian. The instrumentation comprised a Grimm NanoCheck sensor for particle number (25-300 nm and a Grimm OPC for particle mass concentrations. The mobile measurements conducted at a time resolution of 10 s revealed rich details in the spatio-temporal distribution of urban particles that were not visible in fixed-site measurements. Motor traffic proved to be a major source of particle number and mass in the area, although the corresponding concentrations declined rapidly when moving away from the traffic sources. The experiments demonstrate that traffic-free zones and green park areas are useful measures to limit outdoor exposure to traffic-related particles even if they are rather modest in size. Unexpected findings include high fine particle concentrations (PM[0.25;1] near outdoor seating areas of restaurants, and the apparent dependence of coarse particle concentrations (PM[2.5;10] on the ability of surfaces to release particles by resuspension. The study illustrates the usefulness of the spatial sensing of airborne particles in the urban roughness layer and encourages the use of such data for the validation of micro-scale dispersion models.

  10. C2-C6 background hydrocarbon concentrations monitored at a roof top and green park site, in Dublin City centre.

    Science.gov (United States)

    O'Donoghue, R T; Broderick, B M

    2007-09-01

    A 5 week monitoring campaign was carried out in Dublin City centre, to establish which site gave a more accurate background city centre estimation: a roof-top or green field site. This background represented a conservative estimate of HC exposure in Dublin City centre, useful for quantifying health effects related to this form of pollution and also for establishing a local background relative to the four surrounding main roads when the wind direction is travelling towards each road with the background receptor upwind. Over the entire monitoring campaign, the lowest concentrations and relative standard deviations were observed at the green field site, regardless of time of day or meteorological effects.

  11. Measurement of airborne particle concentrations near the Sunset Crater volcano, Arizona.

    Science.gov (United States)

    Benke, Roland R; Hooper, Donald M; Durham, James S; Bannon, Donald R; Compton, Keith L; Necsoiu, Marius; McGinnis, Ronald N

    2009-02-01

    Direct measurements of airborne particle mass concentrations or mass loads are often used to estimate health effects from the inhalation of resuspended contaminated soil. Airborne particle mass concentrations were measured using a personal sampler under a variety of surface-disturbing activities within different depositional environments at both volcanic and nonvolcanic sites near the Sunset Crater volcano in northern Arizona. Focused field investigations were performed at this analog site to improve the understanding of natural and human-induced processes at Yucca Mountain, Nevada. The level of surface-disturbing activity was found to be the most influential factor affecting the measured airborne particle concentrations, which increased over three orders of magnitude relative to ambient conditions. As the surface-disturbing activity level increased, the particle size distribution and the majority of airborne particle mass shifted from particles with aerodynamic diameters less than 10 mum (0.00039 in) to particles with aerodynamic diameters greater than 10 mum (0.00039 in). Under ambient conditions, above average wind speeds tended to increase airborne particle concentrations. In contrast, stronger winds tended to decrease airborne particle concentrations in the breathing zone during light and heavy surface-disturbing conditions. A slight increase in the average airborne particle concentration during ambient conditions was found above older nonvolcanic deposits, which tended to be finer grained than the Sunset Crater tephra deposits. An increased airborne particle concentration was realized when walking on an extremely fine-grained deposit, but the sensitivity of airborne particle concentrations to the resuspendible fraction of near-surface grain mass was not conclusive in the field setting when human activities disturbed the bulk of near-surface material. Although the limited sample size precluded detailed statistical analysis, the differences in airborne particle

  12. Factors affecting the concentration of outdoor particles indoors (COPI): Identification of data needs and existing data

    Energy Technology Data Exchange (ETDEWEB)

    Thatcher, Tracy L.; McKone, Thomas E.; Fisk, William J.; Sohn, Michael D.; Delp, Woody W.; Riley, William J.; Sextro, Richard G.

    2001-12-01

    The process of characterizing human exposure to particulate matter requires information on both particle concentrations in microenvironments and the time-specific activity budgets of individuals among these microenvironments. Because the average amount of time spent indoors by individuals in the US is estimated to be greater than 75%, accurate characterization of particle concentrations indoors is critical to exposure assessments for the US population. In addition, it is estimated that indoor particle concentrations depend strongly on outdoor concentrations. The spatial and temporal variations of indoor particle concentrations as well as the factors that affect these variations are important to health scientists. For them, knowledge of the factors that control the relationship of indoor particle concentrations to outdoor levels is particularly important. In this report, we identify and evaluate sources of data for those factors that affect the transport to and concentration of outdoor particles in the indoor environment. Concentrations of particles indoors depend upon the fraction of outdoor particles that penetrate through the building shell or are transported via the air handling (HVAC) system, the generation of particles by indoor sources, and the loss mechanisms that occur indoors, such as deposition. To address these issues, we (i) identify and assemble relevant information including the behavior of particles during air leakage, HVAC operations, and particle filtration; (ii) review and evaluate the assembled information to distinguish data that are directly relevant to specific estimates of particle transport from those that are only indirectly useful and (iii) provide a synthesis of the currently available information on building air-leakage parameters and their effect on indoor particle matter concentrations.

  13. Cadmium background concentrations to establish reference quality values for soils of São Paulo State, Brazil.

    Science.gov (United States)

    de Oliveira, Vinicius Henrique; de Abreu, Cleide Aparecida; Coelho, Ricardo Marques; Melo, Leônidas Carrijo Azevedo

    2014-03-01

    Proper assessment of soil cadmium (Cd) concentrations is essential to establish legislative limits. The present study aimed to assess background Cd concentrations in soils from the state of São Paulo, Brazil, and to correlate such concentrations with several soil attributes. The topsoil samples (n = 191) were assessed for total Cd contents and for other metals using the USEPA 3051A method. The background concentration was determined according to the third quartile (75th). Principal component analysis, Spearman correlation, and multiple regressions between Cd contents and other soil attributes (pH, cation exchange capacity (CEC), clay content, sum of bases, organic matter, and total Fe, Al, Zn, and Pb levels) were performed. The mean Cd concentration of all 191 samples was 0.4 mg kg(-1), and the background concentration was 0.5 mg kg(-1). After the samples were grouped by parent material (rock origin) and soil type, the background Cd content varied, i.e., soils from igneous, metamorphic, and sedimentary rocks harbored 1.5, 0.4, and 0.2 mg kg(-1) of Cd, respectively. The background Cd content in Oxisols (0.8 mg kg(-1)) was higher than in Ultisols (0.3 mg kg(-1)). Multiple regression demonstrated that Fe was primarily attributed to the natural Cd contents in the soils (R (2) = 0.79). Instead of a single Cd background concentration value representing all São Paulo soils, we propose that the concentrations should be specific for at least Oxisols and Ultisols, which are the primary soil types.

  14. The interaction of natural background gamma radiation with depleted uranium micro-particles in the human body.

    Science.gov (United States)

    Pattison, John E

    2013-03-01

    In this study, some characteristics of the photo-electrons produced when natural background gamma radiation interacts with micron-sized depleted uranium (DU) particles in the human body have been estimated using Monte Carlo simulations. In addition, an estimate has been made of the likelihood of radiological health effects occurring due to such an exposure. Upon exposure to naturally occurring background gamma radiation, DU particles in the body will produce an enhancement of the dose to the tissue in the immediate vicinity of the particles due to the photo-electric absorption of the radiation in the particle. In this study, the photo-electrons produced by a 10 μm-size particle embedded in tissue at the centre of the human torso have been investigated. The mean energies of the photo-electrons in the DU particle and in the two consecutive immediately surrounding 2 μm-wide tissue shells around the particle were found to be 38, 49 and 50 keV, respectively, with corresponding ranges of 1.3, 38 and 39 μm, respectively. The total photo-electron fluence-rates in the two consecutive 2 μm-wide tissue layers were found to be 14% and 7% of the fluence-rate in the DU particle, respectively. The estimated dose enhancement due to one 10 μm-sized DU particle in 1 cm(3) of tissue was less than 2 in 10 million of the dose received by the tissue without a particle being present. The increase in risk of death from cancer due to this effect is consequently insignificant. PMID:23295360

  15. Concentration levels and source apportionment of ultrafine particles in road microenvironments

    Science.gov (United States)

    Argyropoulos, G.; Samara, C.; Voutsa, D.; Kouras, A.; Manoli, E.; Voliotis, A.; Tsakis, A.; Chasapidis, L.; Konstandopoulos, A.; Eleftheriadis, K.

    2016-03-01

    A mobile laboratory unit (MOBILAB) with on-board instrumentation (Scanning Mobility Particle Sizer, SMPS; Ambient NOx analyzer) was used to measure size-resolved particle number concentrations (PNCs) of quasi-ultrafine particles (UFPs, 9-372 nm), along with NOx, in road microenvironments. On-road measurements were carried out in and around a large Greek urban agglomeration, the Thessaloniki Metropolitan Area (TMA). Two 2-week measurement campaigns were conducted during the warm period of 2011 and the cold period of 2012. During each sampling campaign, MOBILAB was driven through a 5-day inner-city route and a second 5-day external route covering in total a wide range of districts (urban, urban background, industrial and residential), and road types (major and minor urban roads, freeways, arterial and interurban roads). All routes were conducted during working days, in morning and in afternoon hours under real-world traffic conditions. Spatial classification of MOBILAB measurements involved the assignment of measurement points to location bins defined by the aspect ratio of adjacent urban street canyons (USCs). Source apportionment was further carried out, by applying Positive Matrix Factorization (PMF) to particle size distribution data. Apportioned PMF factors were interpreted, by employing a two-step methodology, which involved (a) statistical association of PMF factor contributions with 12 h air-mass back-trajectories ending at the TMA during MOBILAB measurements, and (b) Multiple Linear Regression (MLR) using PMF factor contributions as the dependent variables, while relative humidity, solar radiation flux, and vehicle speed were used as the independent variables. The applied data analysis showed that low-speed cruise and high-load engine operation modes are the two dominant sources of UFPs in most of the road microenvironments in the TMA, with significant contributions from background photochemical processes during the warm period, explaining the reversed

  16. Minimizing Concentration Effects in Water-Based, Laminar-Flow Condensation Particle Counters

    OpenAIRE

    Lewis, Gregory S.; Hering, Susanne V.

    2013-01-01

    Concentration effects in water condensation systems, such as used in the water-based condensation particle counter, are explored through numeric modeling and direct measurements. Modeling shows that the condensation heat release and vapor depletion associated with particle activation and growth lowers the peak supersaturation. At higher number concentrations, the diameter of the droplets formed is smaller, and the threshold particle size for activation is higher. This occurs in both cylindric...

  17. Long-term comparative study of columnar and surface mass concentration aerosol properties in a background environment

    Science.gov (United States)

    Bennouna, Y. S.; Cachorro, V. E.; Mateos, D.; Burgos, M. A.; Toledano, C.; Torres, B.; de Frutos, A. M.

    2016-09-01

    The relationship between columnar and surface aerosol properties is not a straightforward problem. The Aerosol Optical Depth (AOD), Ångström exponent (AE), and ground-level Particulate Matter (PMX, x = 10 or 2.5 μm) data have been studied from a climatological point of view. Despite the different meanings of AOD and PMx both are key and complementary quantities that quantify aerosol load in the atmosphere and many studies intend to find specific relationships between them. Related parameters such as AE and PM ratio (PR = PM2.5/PM10), giving information about the predominant particle size, are included in this study on the relationships between columnar and surface aerosol parameters. This study is based on long measurement records (2003-2014) obtained at two nearby background sites from the AERONET and EMEP networks in the north-central area of Spain. The climatological annual cycle of PMx shows two maxima along the year (one in late-winter/early-spring and another in summer), but this cycle is not followed by the AOD which shows only a summer maximum and a nearly bell shape. However, the annual means of both data sets show strong correlation (R = 0.89) and similar decreasing trends of 40% (PM10) and 38% (AOD) for the 12-year record. PM10 and AOD daily data are moderately correlated (R = 0.58), whereas correlation increases for monthly (R = 0.74) and yearly (R = 0.89) means. Scatter plots of AE vs. AOD and PR vs. PM10 have been used to characterize aerosols over the region. The PR vs. AE scatterplot of daily data shows no correlation due to the prevalence of intermediate-sized particles. As day-to-day correlation is low (especially for high turbidity events), a binned analysis was also carried out to establish consistent relationships between columnar and surface quantities, which is considered to be an appropriate approach for environmental and climate studies. In this way the link between surface concentrations and columnar remote sensing data is shown to

  18. Evaluation of Background Concentrations of Contaminants in an Unusual Desert Arroyo Near a Uranium Mill Tailings Disposal Cell - 12260

    Energy Technology Data Exchange (ETDEWEB)

    Bush, Richard P. [U.S. Department of Energy Office of Legacy Management (United States); Morrison, Stan J. [S.M. Stoller Corporation (United States)

    2012-07-01

    The U.S. Department of Energy (DOE) Office of Legacy Management (LM) manages 27 sites that have groundwater containing uranium concentrations above background levels. The distal portions of the plumes merge into background groundwater that can have 50 μg/L or more uranium. Distinguishing background from site-related uranium is often problematic, but it is critical to determining if remediation is warranted, establishing appropriate remediation goals, and evaluating disposal cell performance. In particular, groundwater at disposal cells located on the upper Cretaceous Mancos Shale may have relatively high background concentrations of uranium. Elevated concentrations of nitrate, selenium, and sulfate accompany the uranium. LM used geologic analogs and uranium isotopic signatures to distinguish background groundwater from groundwater contaminated by a former uranium processing site. The same suite of contaminants is present in groundwater near former uranium processing sites and in groundwater seeps emanating from the Mancos Shale over a broad area. The concentrations of these contaminants in Many Devils Wash, located near LM's Shiprock disposal cell, are similar to those in samples collected from many Mancos seeps, including two analog sites that are 8 to 11 km from the disposal cell. Samples collected from Many Devils Wash and the analog sites have high AR values (about 2.0)-in contrast, groundwater samples collected near the tailings disposal cell have AR values near 1.0. These chemical signatures raise questions about the origin of the contamination seeping into Many Devils Wash. (authors)

  19. Assessment of background concentrations of organometallic compounds (methylmercury, ethyllead and butyl- and phenyltin) in French aquatic environments.

    Science.gov (United States)

    Cavalheiro, Joana; Sola, Cristina; Baldanza, Julie; Tessier, Emmanuel; Lestremau, François; Botta, Fabrizio; Preud'homme, Hugues; Monperrus, Mathilde; Amouroux, David

    2016-05-01

    The aim of this work is to estimate background concentrations of organometallic compounds, such as tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPhT), diphenyltin (DPhT), monophenyltin (MPhT), methylmercury (MeHg), inorganic mercury (iHg) and diethyllead (Et2Pb) in the aquatic environment at the French national scale. Both water and sediment samples were collected all over the country, resulting in 152 water samples and 123 sediment samples collected at 181 sampling points. Three types of surface water bodies were investigated: rivers (140 sites), lakes (19 sites) and coastal water (42 sites), spread along the 11 French river basins. The choice of sites was made on the basis of previous investigation results and the following target criteria: reference, urban sites, agricultural and industrial areas. The analytical method was properly validated for both matrices prior to analysis, resulting in low limits of quantification (LOQ), good precision and linearity in agreement with the Water Framework Directive demands. The results were first evaluated as a function of their river basins, type of surrounding pressure and water bodies. Later, background concentrations at the French national scale were established for both water and sediment matrices, as well as their threshold, i.e., the concentration that distinguishes background from anomalies or contaminations. Background concentrations in water are ranging between MBT, DBT and TBT, respectively. For sediments, background concentrations were set as MBT, DBT, TBT and DPhT, respectively. TBT occurs in higher concentrations than the available environmental protection values in 24 and 38 sampling sites for both water and sediment samples, respectively. Other phenyltins (MPhT and TPhT) did not occur above their LOQ and therefore no background was possible to establish. Throughout this work, which is the first assessment of background concentrations for organometallic compounds at the French national

  20. Background Concentrations for Use in the Operational Street Pollution Model (OSPM)

    DEFF Research Database (Denmark)

    Jensen, S. S.

    A background model has been developed for application in the Operational Street Pollution Model (OSPM) in context of long-term exposure modelling. The back ground model is based on a semi-empirical method founded on a few monitor stations that estimates standardised one hour time-series of urban...

  1. Chemical characterization of submicron aerosol and particle growth events at a national background site (3295 m a.s.l. in the Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    W. Du

    2015-05-01

    Full Text Available Atmospheric aerosols exert highly uncertain impacts on radiative forcing and also have detrimental effects on human health. While aerosol particles are widely characterized in megacities in China, aerosol composition, sources and particle growth in rural areas in the Tibetan Plateau remain less understood. Here we present the results from an autumn study that was conducted from 5 September to 15 October 2013 at a national background monitoring station (3295 m a.s.l. in the Tibetan Plateau. The submicron aerosol composition and particle number size distributions were measured in situ with an Aerodyne Aerosol Chemical Speciation Monitor (ACSM and a Scanning Mobility Particle Sizer (SMPS. The average mass concentration of submicron aerosol (PM1 is 11.9 μg m−3 (range: 1.0–78.4 μg m−3 for the entire study, which is much lower than those observed at urban and rural sites in eastern China. Organics dominated PM1 on average accounting for 43%, followed by sulfate (28% and nitrate (1%. Positive matrix factorization analysis of ACSM organic aerosol (OA mass spectra identified an oxygenated OA (OOA and a biomass burning OA (BBOA. The OOA dominated OA composition accounting for 85% on average, 17% of which was inferred from aged BBOA. The BBOA contributed a considerable fraction of OA (15% due to the burning of cow dung and straws in September. New particle formation and growth events were frequently observed (80% of time throughout the study. The average particle growth rate is 2.0 nm h−1 (range: 0.8–3.2 nm h−1. By linking the evolution of particle number size distribution to aerosol composition, we found an elevated contribution of organics during particle growth periods and also a positive relationship between the growth rate and the fraction of OOA in OA, which potentially indicates an important role of organics in particle growth in the Tibetan Plateau.

  2. PM10 Concentration levels at an urban and background site in Cyprus: The impact of urban sources and dust storms

    OpenAIRE

    Achilleos, Souzana; Evans, John S.; Yiallouros, Panayiotis K.; Kleanthous, Savvas; Schwartz, Joel; Koutrakis, Petros

    2014-01-01

    Air quality in Cyprus is influenced by both local and transported pollution including desert dust storms. We examined PM10 concentration data collected in Nicosia (urban representative) from April 1, 1993 through December 11, 2008, and Ayia Marina (rural background representative) from January 1, 1999 through December 31, 2008. Measurements were conducted using a Tapered Element Oscillating Micro-balance (TEOM). PM10 concentrations, meteorological records and satellite data were used to ident...

  3. Concentrations of PAHs in atmospheric particles (PM-10) and roadside soil particles collected in Kuala Lumpur, Malaysia

    Science.gov (United States)

    Omar, Nasr Yousef M. J.; Abas, M. Radzi Bin; Ketuly, Kamal Aziz; Tahir, Norhayati Mohd

    The concentrations of polycyclic aromatic hydrocarbons (PAHs) in atmospheric particles and roadside soil particles were measured at eight locations in the city center and the suburb of Kuala Lumpur, Malaysia. Atmospheric particles were collected using high-volume PM-10 sampler on glass fiber filters over 24 h average sampling period. Both types of samples were extracted with dichloromethane by ultrasonic agitation. The extracts were then fractionated on an alumina-silica column and the aromatic fraction was subjected to gas chromatography-mass spectrometric (GC-MS) analysis. Total PAH concentrations in the atmospheric particles and roadside soil particles were found to be 6.28±4.35 ng m -3 and 0.22±0.11 μg g -1, respectively. Benzo[ g, h, i]perylene and coronene were found to be the most abundant PAHs in airborne particles at all locations. The most abundant PAHs in the roadside soil particles were fluoranthene, pyrene and phenanthrene.

  4. Particle concentration and flux dynamics in the atmospheric boundary layer as the indicator of formation mechanism

    Directory of Open Access Journals (Sweden)

    J. Lauros

    2010-08-01

    Full Text Available We carried out column model simulations to study particle fluxes and deposition and to evaluate different particle formation mechanisms at a boreal forest site in Finland. We show that kinetic nucleation of sulphuric acid cannot be responsible for new particle formation alone as the vertical profile of particle number distribution does not correspond to observations. Instead organic induced nucleation leads to good agreement confirming the relevance of the aerosol formation mechanism including organic compounds emitted by biosphere.

    Simulation of aerosol concentration inside the atmospheric boundary layer during nucleation days shows highly dynamical picture, where particle formation is coupled with chemistry and turbulent transport. We have demonstrated suitability of our turbulent mixing scheme in reproducing most important characteristics of particle dynamics inside the atmospheric boundary layer. Deposition and particle flux simulations show that deposition affects noticeably only the smallest particles at the lowest part of the atmospheric boundary layer.

  5. Background concentrations and fluxes of atmospheric ammonia over a deciduous forest

    DEFF Research Database (Denmark)

    Hansen, K.; Pryor, S. C.; Boegh, E.;

    2015-01-01

    . In this study, we present two months of half-hourly NH3 fluxes and concentrations measured using a Relaxed Eddy Accumulation system during late summer and fall 2013 above a remote forest site in the central Midwest in USA. Supplementary nitric acid (HNO3) flux and size-resolved aerosol-N measurements are used.......11 μg NH3-N m−2 s−1. The wetness of the forest surfaces (assessed using a proxy of time since precipitation) was found to be crucial in controlling both deposition and emission of atmospheric NH3. Size resolved aerosol concentrations (of NH4+, NO3−, Cl− and SO42−) indicated that the aerosol and gas...

  6. Radon in indoor concentrations and indoor concentrations of metal dust particles in museums and other public buildings.

    Science.gov (United States)

    Carneiro, G L; Braz, D; de Jesus, E F; Santos, S M; Cardoso, K; Hecht, A A; Dias da Cunha, Moore K

    2013-06-01

    The aim of this study was to evaluate the public and occupational exposure to radon and metal-bearing particles in museums and public buildings located in the city of Rio de Janeiro, Brazil. For this study, four buildings were selected: two historic buildings, which currently house an art gallery and an art museum; and two modern buildings, a chapel and a club. Integrated radon concentration measurements were performed using passive radon detectors with solid state nuclear track detector-type Lexan used as nuclear track detector. Air samplers with a cyclone were used to collect the airborne particle samples that were analyzed by the particle-induced X-ray emission technique. The average unattached-radon concentrations in indoor air in the buildings were above 40 Bq/m(3), with the exception of Building D as measured in 2009. The average radon concentrations in indoor air in the four buildings in 2009 were below the recommended reference level by World Health Organization (100 Bq/m(3)); however, in 2011, the average concentrations of radon in Buildings A and C were above this level, though lower than 300 Bq/m(3). The average concentrations of unattached radon were lower than 148 Bq/m(3) (4pCi/L), the USEPA level recommended to take action to reduce the concentrations of radon in indoor air. The unattached-radon average concentrations were also lower than the value recommended by the European Union for new houses. As the unattached-radon concentrations were below the international level recommended to take action to reduce the radon concentration in air, it was concluded that during the period of sampling, there was low risk to human health due to the inhalation of unattached radon in these four buildings.

  7. Shear-induced particle diffusion and its effects on the flow of concentrated suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Acrivos, A. [City College of CUNY, New York, NY (United States)

    1996-12-31

    The mechanism underlying shear-induced particle diffusion in concentrated suspensions is clarified. Examples are then presented where this diffusion process plays a crucial role in determining the manner by which such suspensions flow under laminar conditions.

  8. Tire-tread and bitumen particle concentrations in aerosol and soil samples

    DEFF Research Database (Denmark)

    Fauser, Patrik; Tjell, Jens Christian; Mosbæk, Hans;

    2002-01-01

    ire and bitumen particle concentrations are determined in aerosol and soil samples. They each constitute about 5 wt-% of the total suspended particulate matter (TSP) in inner city air, collected with a Berner low pressure impactor, 5 m from a road. The particle size distribution shows that 92% of...

  9. Potential cultivation of Hordeum vulgare L. in soils with high mercury background concentrations.

    Science.gov (United States)

    Sierra, M J; Millán, R; Cardona, A I; Schmid, T

    2011-09-01

    Experimental work was carried out under close-to-real conditions to study mercury uptake by Hordeum vulgare L. cultivated in lysimeter experiments. The soil in the lysimeter experiment was obtained from a test plot located near Almadén (Spain) and had a mean mercury content of 22.9 mg kg(-1). A sequence of four crops was sown starting in autumn 2000 and repeated on a yearly basis until 2004. The first crop was grown in the field prior to the extraction of 5 one-cubic-meter lysimeters. The succeeding crops were sown in the lysimeter experiments at the CIEMAT Research Centre (Madrid, Spain). Samples of root and shoot were obtained during the four seasons. Concentrations of mercury at plant maturity in roots vary between I and 3 mg kg(-1) and in straw and grain the concentrations range from 72 to 480 microg kg(-1) and from 5 to 257 microg kg(-1), respectively. In order to assess the potential risk for human health and animal feed, an evaluation of the mercury content in the edible part of the crop has been carried out. According to legislation, there is no human health intoxication risk with a balanced consumption; otherwise, the forage use would have to be controlled. PMID:21972517

  10. Human pulmonary responses to experimental inhalation of high concentration fine and ultrafine magnesium oxide particles.

    OpenAIRE

    Kuschner, W G; Wong, H; D'Alessandro, A; Quinlan, P; Blanc, P.D.

    1997-01-01

    Exposure to air polluted with particles less than 2.5 micron in size is associated epidemiologically with adverse cardiopulmonary health consequences in humans. The goal of this study was to characterize human pulmonary responses to controlled experimental high-dose exposure to fine and ultrafine magnesium oxide particles. We quantified bronchoalveolar lavage (BAL) cell and cytokine concentrations, pulmonary function, and peripheral blood neutrophil concentrations in six healthy volunteers 18...

  11. Real-time measurement of aerosol particle concentration at high temperatures; Hiukkaspitoisuuden reaaliaikainen mittaaminen korkeassa laempoetilassa

    Energy Technology Data Exchange (ETDEWEB)

    Keskinen, J.; Hautanen, J.; Laitinen, A. [Tampere Univ. of Technology (Finland). Physics

    1997-10-01

    The aim of this project is to develop a new method for continuous aerosol particle concentration measurement at elevated temperatures (up to 800-1000 deg C). The measured property of the aerosol particles is the so called Fuchs surface area. This quantity is relevant for diffusion limited mass transfer to particles. The principle of the method is as follows. First, aerosol particles are charged electrically by diffusion charging process. The charging takes place at high temperature. After the charging, aerosol is diluted and cooled. Finally, aerosol particles are collected and the total charge carried by the aerosol particles is measured. Particle collection and charge measurement take place at low temperature. Benefits of this measurement method are: particles are charged in-situ, charge of the particles is not affected by the temperature and pressure changes after sampling, particle collection and charge measurement are carried out outside the process conditions, and the measured quantity is well defined. The results of this study can be used when the formation of the fly ash particles is studied. Another field of applications is the study and the development of gasification processes. Possibly, the method can also be used for the monitoring the operation of the high temperature particle collection devices. (orig.)

  12. On the regional distributions of background carbon monoxide concentrations observed in East Asia during 1991-2008

    Science.gov (United States)

    Kim, H. S.; Chung, Y. S.; Tans, P. P.

    2010-02-01

    The carbon monoxide (CO) concentrations observed at Mt. Waliguan in China (WLG), Ulaan Uul in Mongolia (UUM), Tae-ahn Peninsula in Korea (TAP) and Ryori in Japan (RYO) were analysed between 1991 and 2008. The average annual concentration of CO, a toxic air pollutant, was the highest at TAP (235±44 ppb), followed by RYO (169±35 ppb), UUM (154±27 ppb) and WLG (138±24 ppb). These data obtained in East Asia were also compared with CO data from Mauna Loa, Hawaii. CO tends to be highest in spring and lowest in summer in East Asia, with the exception of WLG. TAP had the highest CO concentrations in all seasons compared with WLG, UUM and RYO, and displays a wide short-term variability in concentration. This is caused by large-scale air pollution owing to its downwind location, close to continental East Asia. CO concentrations observed at TAP were analysed as follows: according to the origin of the isentropic backward trajectory and its transport passage; as continental background airflows (CBG); regionally polluted continental airflows (RPC); oceanic background airflows (OBG); and partly perturbed oceanic airflows (PPO). The high concentrations of CO at TAP are because of the airflow originating from the East Asian continent, rather than the North Pacific. RPCs, which pass through eastern China, appear to have high CO concentrations in spring, autumn and winter. It is noteworthy that the overall trend at TAP does not show an increase despite the fact that energy use in China approximately doubled from 1991 to 2008. OBGs, however, are affected by North Pacific air masses with low CO concentrations in summer.

  13. NUMBER CONCENTRATION, SIZE DISTRIBUTION AND FINE PARTICLE FRACTION OF TROPOSPHERIC AND STRATOSPHERIC AEROSOLS

    Institute of Scientific and Technical Information of China (English)

    Li Xu; Guangyu Shi; Li Zhang; Jun Zhou; Yasunobu Iwasaka

    2003-01-01

    Aerosol observations were carried out at Xianghe Scientific Balloon Base (39.45°N, 117°E) using a stratospheric balloon. The particle number concentrations of the tropospheric and stratospheric aerosols were directly explored.The vertical distributions of the number concentration, number-size (that is, particle number versus particle size)distribution, and the fraction of fine particles (0.5 μm>r>0.15 μm/r>0.15 μm) are reported in this paper. The profiles of particle concentration present multi-peak phenomenon. The pattern of size distribution for atmospheric aerosol indicates a tri-modal (r=~0.2 μm, ~0.88 μm and ~7.0 μm) and a bi-modal (r=~0.13 μm and 2.0 μm). The number-size distribution almost fits the Junge distribution for particles with r<0.5 μm in the stratosphere of 1993 and the troposphere of 1994. But the distributions of coarse particles (r>0.5 μm) are not uniform. The number-size distribution exhibits also a wide size range in the troposphere of 1993. The results demonstrate that fine particles represent the major portion in the troposphere during the measurement period, reaching as high as 95% in 1994. Certain coarse particle peaks in the troposphere were attributed to clouds and other causes, and in the stratosphere to volcanic eruption. The stratospheric aerosol layer consists of unique fractions of fine or coarse particles depending on their sources. In summary, the process of gas-to-particles conversion was active and the coarse particles were rich over the Xianghe area. The measurements also demonstrate that the spatial and temporal atmospheric aerosol distributions are nonuniform and changeful.

  14. Wood dust particle and mass concentrations and filtration efficiency in sanding of wood materials.

    Science.gov (United States)

    Welling, Irma; Lehtimäki, Matti; Rautio, Sari; Lähde, Tero; Enbom, Seppo; Hynynen, Pasi; Hämeri, Kaarle

    2009-02-01

    The importance of fine particles has become apparent as the knowledge of their effects on health has increased. Fine particle concentrations have been published for outside air, plasma arc cutting, welding, and grinding, but little data exists for the woodworking industry. Sanding was evaluated as the producer of the woodworking industry's finest particles, and was selected as the target study. The number of dust particles in different particle size classes and the mass concentrations were measured in the following environments: workplace air during sanding in plywood production and in the inlet and return air; in the dust emission chamber; and in filter testing. The numbers of fine particles were low, less than 10(4) particles/cm(3) (10(7) particles/L). They were much lower than typical number concentrations near 10(6) particles/cm(3) measured in plasma arc cutting, grinding, and welding. Ultrafine particles in the size class less than 100 nm were found during sanding of MDF (medium density fiberboard) sheets. When the cleaned air is returned to the working areas, the dust content in extraction systems must be monitored continuously. One way to monitor the dust content in the return air is to use an after-filter and measure pressure drop across the filter to indicate leaks in the air-cleaning system. The best after-filtration materials provided a clear increase in pressure drop across the filter in the loading of the filter. The best after-filtration materials proved to be quite effective also for fine particles. The best mass removal efficiencies for fine particles around 0.3 mum were over 80% for some filter materials loaded with sanding wood dust.

  15. The Effect of Particle Concentration on the Heating Rate of Ferrofluids for Magnetic Hyperthermia

    Science.gov (United States)

    Malaescu, I.; Marin, C. N.; Bunoiu, M.; Fannin, P. C.; Stefu, N.; Iordaconiu, L.

    2015-12-01

    The complex magnetic susceptibility χ(f) = χ'(f) - i χ″(f), of a ferrofluid sample with magnetite particles dispersed in kerosene and stabilized with oleic acid, over the range 0.1 GHz to 6 GHz, was determined. The initial sample has been successively diluted with kerosene (with a dilution rate of 2/3), thus obtaining further three samples. Using the complex magnetic susceptibility measurements of each sample, the frequency field and particle concentration dependencies of the heating rate of the ferrofluid samples, were analyzed. The results show the possibility of using the heating rate of ferrofluid samples with different particle concentrations, in hyperthermia applications.

  16. Transport and Retention of Engineered Nanoporous Particles in Porous Media: Effects of Concentration and Flow Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Shang, Jianying; Liu, Chongxuan; Wang, Zheming

    2013-01-20

    Engineered nanoporous particles are an important class of nano-structured materials that can be functionalized in their internal surfaces for various applications including groundwater contaminant sequestration. This paper reported a study of transport and retention of engineered nanoporous silicate particles (ENSPs) that are designed for treatment and remediation of contaminants such as uranium in groundwater and sediments. The transport and retention of ENSPs were investigated under variable particle concentrations and dynamic flow conditions in a synthetic groundwater that mimics field groundwater chemical composition. The dynamic flow condition was achieved using a flow-interruption (stop-flow) approach with variable stop-flow durations to explore particle retention and release kinetics. The results showed that the ENSPs transport was strongly affected by the particle concentrations and dynamic flow conditions. A lower injected ENSPs concentration and longer stop-flow duration led to a more particle retention. The experimental data were used to evaluate the applicability of various kinetic models that were developed for colloidal particle retention and release in describing ENSPs transport. Model fits suggested that the transport and retention of ENSPs were subjected to a complex coupling of reversible attachment/detachment and straining/liberation processes. Both experimental and modeling results indicated that dynamic groundwater flow condition is an important parameter to be considered in exploring and modeling engineered particle transport in subsurface porous media.

  17. The Dirac particle on central backgrounds and the anti-de Sitter oscillator

    CERN Document Server

    Cotaescu, I I

    1998-01-01

    It is shown that, for spherically symmetric static backgrounds, a simple reduced Dirac equation can be obtained by using the Cartesian tetrad gauge in Cartesian holonomic coordinates. This equation is manifestly covariant under rotations so that the spherical coordinates can be separated in terms of angular spinors like in special relativity, obtaining a pair of radial equations and a specific form of the radial scalar product. As an example, we analytically solve the anti-de Sitter oscillator giving the formula of the energy levels and the form of the corresponding eigenspinors.

  18. Particle concentrations and number size distributions in the planetary boundary layer derived from airship based measurements

    Science.gov (United States)

    Tillmann, Ralf; Zhao, Defeng; Ehn, Mikael; Hofzumahaus, Andreas; Holland, Frank; Rohrer, Franz; Kiendler-Scharr, Astrid; Wahner, Andreas

    2014-05-01

    Atmospheric particles play a key role for regional and global climate due to their direct and indirect radiative forcing effects. The concentration and size of the particles are important variables to these effects. Within the continental planetary boundary layer (PBL) the particle number size distribution is influenced by meteorological parameters, local sinks and sources resulting in variable spatial distributions. However, measurements of particle number size distributions over a broad vertical range of the PBL are rare. The airship ZEPPELIN NT is an ideal platform to measure atmospheric aerosols on a regional scale within an altitude range up to 1000 m. For campaigns in the Netherlands, Northern Italy and South Finland in 2012 and 2013 the airship was deployed with a wide range of instruments, including measurements of different trace gases, short lived radicals, solar radiation, aerosols and meteorological parameters. Flights were carried out at different times of the day to investigate the influence of the diurnal evolution of the PBL on atmospheric trace gases and aerosols. During night and early morning hours the concentration and size distribution of atmospheric particles were found to be strongly influenced by the layered structure of the PBL, i.e. the nocturnal boundary layer and the residual layer. Within the residual layer particle concentrations stay relatively constant as this layer is decoupled from ground sources. The particles persist in the accumulation mode as expected for an aged aerosol. In the nocturnal boundary layer particle concentrations and size are more dynamic with higher concentrations than in the residual layer. A few hours after sunrise, the layered structure of the PBL intermixes. During daytime the PBL is well mixed and a negative concentration gradient with increasing height is observed. Several height profiles at different times of the day and at different locations in Europe were measured. The aerosol measurements will be

  19. The Hawking evaporation of dirac particles in general Kerr-Newman black hole background

    International Nuclear Information System (INIS)

    In 1974, a study proposed that there might be some quantum processes, in which the irreducible mass of a black hole is radiated away. Such a quantum vacuum polarization process is named Hawking evaporation. In 1976, a study discussed the Hawking evaporation of Klein-Gordon particles through Klein-Souter-Heisenberg-Euler formalism. Recently, a study found the solution of the Dirac equations just outside the horizon for quasi-extreme Kerr and Kerr-Newman black holes by means of the decoupled Dirac equations with non-zero mass. The corresponding Hawking thermal spectrum formula was also derived. However, it is unnecessary to impose quasi-extreme conditions on the black holes for solving the equations. In this paper, the authors discuss the general Kerr-Newman black hole directly

  20. Continuous decline of background activity concentrations of {sup 3}H, {sup 90}Sr and {sup 137}Cs in hydrosphere

    Energy Technology Data Exchange (ETDEWEB)

    Juranova, E.; Hanslik, E.; Maresova, D. [T.G. Masaryk Water Research Institute (Czech Republic)

    2014-07-01

    Main artificial radionuclides - {sup 3}H, {sup 90}Sr and {sup 137}Cs - have occurred in environment since atmospheric tests of nuclear weapons, and later in Europe, since the accident at the Chernobyl nuclear reactor. Hence, these radionuclides can still be detected in samples of surface water and other components of hydrosphere. To assess environmental impact of nuclear facilities, which represent point sources of artificial radioactivity, it is necessary to take into account a decreasing trend of the radionuclides background, observed in water, bottom sediments and biota. The paper describes development of {sup 3}H, {sup 90}Sr and {sup 137}Cs concentrations and balances through an example of vicinity of the Temelin Nuclear Power Plant in South Bohemia in pre-operational (1990-2000) and operational (2001-2012) stage. The concentrations of {sup 137}Cs and {sup 90}Sr were permanently decreasing during the monitored period and they cover up the same radionuclides released from the plant. In addition, similar decreasing trend was observed for tritium concentrations in river sites, which were not affected by the plant, too. In contrast to the other radionuclides, concentrations of tritium detected at the sites affected by the plant were substantially above its background. Document available in abstract form only. (authors)

  1. Analysis of particle-borne odorants emitted from concentrated animal feeding operations.

    Science.gov (United States)

    Yang, Xufei; Lorjaroenphon, Yaowapa; Cadwallader, Keith R; Wang, Xinlei; Zhang, Yuanhui; Lee, Jongmin

    2014-08-15

    Airborne particles are known to serve as a carrier of odors emanating from concentrated animal feeding operations (CAFOs). However, limited quantitative data about particle-borne odorants preclude an accurate assessment of the role of particles in odor transport. This study collected total suspended particulates (TSP) and PM10 (particles with aerodynamic diameter smaller than 10 μm) at the air exhaust of eight types of CAFOs (swine: farrowing, gestation, weaning, and finishing; poultry: manure-belt layer hen, tom turkey, chicken broiler, and cage-free layer hen; in total 20 animal buildings) in multiple seasons, and examined the variability in particle odorant composition with animal operation type, season, and particle size. Fifty-seven non-sulfur-containing odorants were identified and quantitated, including carbonyls, alcohols, acids, phenols, and nitrogen-containing compounds. They in total accounted for 2.19±1.52% TSP and 4.97±3.25% PM10 mass. Acetic acid and ethanol were most abundant but less odor-contributing than phenylacetic acid, indole, dodecanoic acid, and (E,E)-2,4-decadienal, as determined by odor activity value. Particle odorant composition varied significantly with animal operation type, season, and particle size. The TSP and PM10 samples from swine gestation buildings, for example, showed distinctly different odorant compositions than those from tom turkey buildings. The summer TSP and PM10 samples contained in general lower concentrations of short-chain fatty acids but higher concentrations of long-chain fatty acids, aldehydes, and short-chain alcohols than the winter samples. Compared to TSP, PM10 samples from different types of CAFOs shared a more similar odorant composition, contained higher odorant concentrations per mass of particles, and accounted for on average 53.2% of the odor strength of their corresponding TSP samples. PMID:24863138

  2. KINETIC MODELING OF CONSTITUTIVE RELATIONS FOR PARTICLE MOTION IN LOW TO MODERATELY CONCENTRATED FLOWS

    Institute of Scientific and Technical Information of China (English)

    Guangqian WANG; Xudong FU; Xingkui WANG

    2005-01-01

    Formulating underlying mechanisms of concentrated solid-liquid flows is essential for simulation of various industrial processes and natural phenomena. A generalized constitutive model for particle motion in flows with low to moderate solids concentrations is developed. This generalized model facilitates characterization of inelastic collisions, particle-fluid interactions, and shearing effects.Moderately concentrated simple shear flows of a sand-water mixture are analyzed, and comparisons of model predictions and experimental data are in good agreement. This model exhibits sound performance in characterizing particle motion for wide ranges of concentration and shear rate, and may supply a reasonable and competent alternative to previous models developed for dilute and rapid-granular flows when applied to moderately concentrated situations. The concentration approaches zero (C → 0) asymptote is observed at a relatively high shear rate in model predictions.Assumption of low collisional dissipation of the particle phase as C → 0 is more reasonable for this observation, compared to that without the interstitial fluid effect. Accurately modeling energy dissipation is important for characterizing the stability of dilute simple shear flows of solid-liquid mixtures. Incorporating friction forces will also facilitate improvement of the applicability of this generalized model to flows at extremely high concentrations.

  3. Determination of concentration of charged particles in various regions of thunderstorms

    Science.gov (United States)

    Detwiler, A. G.; Mo, Q.

    2015-12-01

    During the Severe Thunderstorm Precipitation and Electrification Study in 2000, data on hydrometeor sizes and charges were obtained in thunderstorms using an optical array probe modified by the New Mexico Institute of Mining and Technology and mounted on the South Dakota School of Mines and Technology armored T-28 research aircraft. Analysis yielded quantitative observations of hydrometeor size and charge data in selected regions of storms with relatively low concentrations of charged particles. In most regions hydrometeor concentrations were so high that there were multiple charged particles in the probe sample volume at the same time and quantitative charge analysis was not possible. While it is impossible to reliably determine individual particle charges in these high concentration regions, we can use Poisson statistics to estimate the total number concentration of charged particles based on the fraction of records with just one particle in them. We compare these number concentrations for different thunderstorm regions, including updrafts, flanking cells, core precipitation regions, and trailing stratiform regions, at approximately the -10 C level, in several thunderstorms. We will discuss the implications of these results for understanding charge-separation processes in thunderstorms.

  4. Modeling the impact of sea-spray on particle concentrations in a coastal city

    Energy Technology Data Exchange (ETDEWEB)

    Pryor, S C; Barthelmie, R J; Schoof, J T; Binkowski, F S; Monache, L D; Stull, R B

    2006-04-19

    An atmospheric chemistry-transport model is used to assess the impacts of sea-spray chemistry on the particle composition in and downwind of a coastal city--Vancouver, British Columbia. Reactions in/on sea-spray affect the entire particle ensemble and particularly the size distribution of particle nitrate. Urban air quality, and particularly airborne particles, is a major concern in terms of human health impacts. Sea-spray is known to be a major component of the particle ensemble at coastal sites yet relatively few air quality models include the interaction of gases with sea-spray and the fate of the particles produced. Sea-spray is not an inert addition to the particle ensemble because heterogeneous chemistry in/on sea-spray droplets changes the droplets composition and the particle size distribution, which impacts deposition and the ion balance in different particle size fractions. It is shown that the ISOPART model is capable of simulating gas and particle concentrations in the coastal metropolis of Vancouver and the surrounding valley. It is also demonstrated that to accurately simulate ambient concentrations of particles and reactive/soluble gases in a coastal valley it is absolutely critical to include heterogeneous chemistry in/on sea-spray. Partitioning of total particle-NO{sub 3}{sup -} between sea-spray and NH{sub 4}NO{sub 3} is highly sensitive to the amount of sea-spray present, and hence the initial vertical profile, sea-spray source functions [48] and the wind speed. When a fixed wind speed is used to initialize the sea-spray vertical profiles, as expected, the sea-spray concentration decays with distance inland, but the particle-NO{sub 3}{sup -} concentration decays more slowly because it is also a function of the uptake rate for HNO{sub 3}. The simulation results imply model analyses of air quality in coastal cities conducted without inclusion of sea-spray interactions may yield highly misleading results in terms of emission sensitivities of the PM

  5. Modelling component evaporation and composition change of traffic-induced ultrafine particles during travel from street canyon to urban background.

    Science.gov (United States)

    Nikolova, Irina; MacKenzie, A Rob; Cai, Xiaoming; Alam, Mohammed S; Harrison, Roy M

    2016-07-18

    We developed a model (CiTTy-Street-UFP) of traffic-related particle behaviour in a street canyon and in the nearby downwind urban background that accounts for aerosol dynamics and the variable vapour pressure of component organics. The model simulates the evolution and fate of traffic generated multicomponent ultrafine particles (UFP) composed of a non-volatile core and 17 Semi-Volatile Organic Compounds (SVOC, modelled as n-alkane proxies). A two-stage modelling approach is adopted: (1) a steady state simulation inside the street canyon is achieved, in which there exists a balance between traffic emissions, condensation/evaporation, deposition, coagulation and exchange with the air above roof-level; and (2) a continuing simulation of the above-roof air parcel advected to the nearby urban park during which evaporation is dominant. We evaluate the component evaporation and associated composition changes of multicomponent organic particles in realistic atmospheric conditions and compare our results with observations from London (UK) in a street canyon and an urban park. With plausible input conditions and parameter settings, the model can reproduce, with reasonable fidelity, size distributions in central London in 2007. The modelled nucleation-mode peak diameter, which is 23 nm in the steady-state street canyon, decreases to 9 nm in a travel time of just 120 s. All modelled SVOC in the sub-10 nm particle size range have evaporated leaving behind only non-volatile material, whereas modelled particle composition in the Aitken mode contains SVOC between C26H54 and C32H66. No data on particle composition are available in the study used for validation, or elsewhere. Measurements addressing in detail the size resolved composition of the traffic emitted UFP in the atmosphere are a high priority for future research. Such data would improve the representation of these particles in dispersion models and provide the data essential for model validation. Enhanced knowledge of the

  6. Modelling component evaporation and composition change of traffic-induced ultrafine particles during travel from street canyon to urban background.

    Science.gov (United States)

    Nikolova, Irina; MacKenzie, A Rob; Cai, Xiaoming; Alam, Mohammed S; Harrison, Roy M

    2016-07-18

    We developed a model (CiTTy-Street-UFP) of traffic-related particle behaviour in a street canyon and in the nearby downwind urban background that accounts for aerosol dynamics and the variable vapour pressure of component organics. The model simulates the evolution and fate of traffic generated multicomponent ultrafine particles (UFP) composed of a non-volatile core and 17 Semi-Volatile Organic Compounds (SVOC, modelled as n-alkane proxies). A two-stage modelling approach is adopted: (1) a steady state simulation inside the street canyon is achieved, in which there exists a balance between traffic emissions, condensation/evaporation, deposition, coagulation and exchange with the air above roof-level; and (2) a continuing simulation of the above-roof air parcel advected to the nearby urban park during which evaporation is dominant. We evaluate the component evaporation and associated composition changes of multicomponent organic particles in realistic atmospheric conditions and compare our results with observations from London (UK) in a street canyon and an urban park. With plausible input conditions and parameter settings, the model can reproduce, with reasonable fidelity, size distributions in central London in 2007. The modelled nucleation-mode peak diameter, which is 23 nm in the steady-state street canyon, decreases to 9 nm in a travel time of just 120 s. All modelled SVOC in the sub-10 nm particle size range have evaporated leaving behind only non-volatile material, whereas modelled particle composition in the Aitken mode contains SVOC between C26H54 and C32H66. No data on particle composition are available in the study used for validation, or elsewhere. Measurements addressing in detail the size resolved composition of the traffic emitted UFP in the atmosphere are a high priority for future research. Such data would improve the representation of these particles in dispersion models and provide the data essential for model validation. Enhanced knowledge of the

  7. Simultaneous measurement of local particle movement, solids concentrations and bubble properties in fluidized bed reactors using a novel fiber optical technique

    Energy Technology Data Exchange (ETDEWEB)

    Tayebi, Davoud

    1998-12-31

    This thesis develops a new method for simultaneous measurements of local flow properties in highly concentrated multiphase flow systems such as gas-solid fluidized bed reactors. The method is based on fiber optical technique and tracer particles. A particle present in the measuring volume in front of the probe is marked with a fluorescent dye. A light source illuminates the particles and the detecting fibres receive reflected light from uncoated particles and fluorescent light from the tracer particle. Using optical filters, the fluorescent light can be distinguished and together with a small fraction of background light from uncoated particles can be used for determination of local flow properties. Using this method, one can simultaneously measure the local movement of a single tracer particle, local bubble properties and the local solids volume fractions in different positions in the bed. The method is independent of the physical properties of the tracer particles. It is also independent of the local solids concentrations in the range of 0 to 60 vol.-%, but is mainly designed for highly concentrated flow systems. A computer programme that uses good signals from at least three sensors simultaneously to calculate the tracer particle velocity in two dimensions have been developed. It also calculates the bubble properties and local solids volume fractions from the same time series. 251 refs., 150 figs., 5 tabs.

  8. Magnetofluidic concentration and separation of non-magnetic particles using two magnet arrays.

    Science.gov (United States)

    Hejazian, Majid; Nguyen, Nam-Trung

    2016-07-01

    The present paper reports the use of diluted ferrofluid and two arrays of permanent magnets for the size-selective concentration of non-magnetic particles. The micro magnetofluidic device consists of a straight channels sandwiched between two arrays of permanent magnets. The permanent magnets create multiple capture zones with minimum magnetic field strength along the channel. The complex interaction between magnetic forces and hydrodynamic force allows the device to operate in different regimes suitable for concentration of non-magnetic particles with small difference in size. Our experimental results show that non-magnetic particles with diameters of 3.1 μm and 4.8 μm can be discriminated and separated with this method. The results from this study could be used as a guide for the design of size-sensitive separation devices for particle and cell based on negative magnetophoresis.

  9. Evaluation of number concentration quantification by single-particle inductively coupled plasma mass spectrometry: microsecond vs. millisecond dwell times.

    Science.gov (United States)

    Abad-Álvaro, Isabel; Peña-Vázquez, Elena; Bolea, Eduardo; Bermejo-Barrera, Pilar; Castillo, Juan R; Laborda, Francisco

    2016-07-01

    The quality of the quantitative information in single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) depends directly on the number concentration of the nanoparticles in the sample analyzed, which is proportional to the flux of nanoparticles through the plasma. Particle number concentrations must be selected in accordance with the data acquisition frequency, to control the precision from counting statistics and the bias, which is produced by the occurrence of multiple-particle events recorded as single-particle events. With quadrupole mass spectrometers, the frequency of data acquisition is directly controlled by the dwell time. The effect of dwell times from milli- to microseconds (10 ms, 5 ms, 100 μs, and 50 μs) on the quality of the quantitative data has been studied. Working with dwell times in the millisecond range, precision figures about 5 % were achieved, whereas using microsecond dwell times, the suitable fluxes of nanoparticles are higher and precision was reduced down to 1 %; this was independent of the dwell time selected. Moreover, due to the lower occurrence of multiple-nanoparticle events, linear ranges are wider when dwell times equal to or shorter than 100 μs are used. A calculation tool is provided to determine the optimal concentration for any instrument or experimental conditions selected. On the other hand, the use of dwell times in the microsecond range reduces significantly the contribution of the background and/or the presence of dissolved species, in comparison with the use of millisecond dwell times. Although the use of dwell times equal to or shorter than 100 μs offers improved performance working in single-particle mode, the use of conventional dwell times (3-10 ms) should not be discarded, once their limitations are known. PMID:27086011

  10. Spontaneous concentrations of solids through two-way drag forces between gas and sedimenting particles

    CERN Document Server

    Lambrechts, Michiel; Capelo, Holly L; Blum, Jürgen; Bodenschatz, Eberhard

    2016-01-01

    The behaviour of sedimenting particles depends on the dust-to-gas ratio of the fluid. Linear stability analysis shows that solids settling in the Epstein drag regime would remain homogeneously distributed in non-rotating incompressible fluids, even when dust-to-gas ratios reach unity. However, the non-linear evolution has not been probed before. Here, we present numerical calculations indicating that in a particle-dense mixture solids spontaneously mix out of the fluid and form swarms overdense in particles by at least a factor 10. The instability is caused by mass-loaded regions locally breaking the equilibrium background stratification. The driving mechanism depends on non-linear perturbations of the background flow and shares some similarity to the streaming instability in accretion discs. The resulting particle-rich swarms may stimulate particle growth by coagulation. In the context of protoplanetary discs, the instability could be relevant for aiding small particles to settle to the midplane in the outer...

  11. Spontaneous concentrations of solids through two-way drag forces between gas and sedimenting particles

    Science.gov (United States)

    Lambrechts, M.; Johansen, A.; Capelo, H. L.; Blum, J.; Bodenschatz, E.

    2016-06-01

    The behaviour of sedimenting particles depends on the dust-to-gas ratio of the fluid. Linear stability analysis shows that solids settling in the Epstein drag regime would remain homogeneously distributed in non-rotating incompressible fluids, even when dust-to-gas ratios reach unity. However, the nonlinear evolution has not been probed before. Here, we present numerical calculations indicating that, in a particle-dense mixture, solids spontaneously mix out of the fluid and form swarms that are overdense in particles by at least a factor 10. The instability is caused by mass-loaded regions locally breaking the equilibrium background stratification. The driving mechanism depends on nonlinear perturbations of the background flow and shares some similarity to the streaming instability in accretion discs. The resulting particle-rich swarms may stimulate particle growth by coagulation. In the context of protoplanetary discs, the instability could be relevant for aiding small particles to settle to the midplane in the outer disc. Inside the gas envelopes of protoplanets, enhanced settling may lead to a reduced dust opacity, which facilitates the contraction of the envelope. We show that the relevant physical set up can be recreated in a laboratory setting. This will allow our numerical calculations to be investigated experimentally in the future.

  12. EVOLUTION OF NUMBER CONCENTRATION OF NANO-PARTICLES UNDERGOING BROWNIAN COAGULATION IN THE TRANSITION REGIME

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-ming; LIN Jian-zhong

    2011-01-01

    Evolution of number concentration of nanoparticles undergoing Brownian coagulation in the transition regime is studied theoretically and numerically.The results show that the curves of particle size distribution move toward the area with large particle diameters,the curve peak becomes lower and the range that particle diameters cover becomes wider as time elapses.In the process of coagulation the particles with small diameter disappear gradually and the particle size distribution remains a log-normal distribution.The change rate of the particle size distribution is more appreciable at the initial stage than that at the final stage.The initial Knudsen number has a significant effect on the coagulation rate which increases with decreasing the initial Knudsen number.The larger the initial geometric standard deviation is,the smaller the curve peak is,and the wider the area that curves cover is.The initial geometric standard deviation has a significant effect on the particle size distribution which can remain a self-preserving state when the initial geometric standard deviation is smaller than 2.With the increase of the diversity of initial particle size,the particle size distribution does not obey the log-normal distribution any more as time elapses.

  13. Achieving secondary prevention low-density lipoprotein particle concentration goals using lipoprotein cholesterol-based data.

    Directory of Open Access Journals (Sweden)

    Simon C Mathews

    Full Text Available BACKGROUND: Epidemiologic studies suggest that LDL particle concentration (LDL-P may remain elevated at guideline recommended LDL cholesterol goals, representing a source of residual risk. We examined the following seven separate lipid parameters in achieving the LDL-P goal of <1000 nmol/L goal for very high risk secondary prevention: total cholesterol to HDL cholesterol ratio, TC/HDL, <3; a composite of ATP-III very high risk targets, LDL-C<70 mg/dL, non-HDL-C<100 mg/dL and TG<150 mg/dL; a composite of standard secondary risk targets, LDL-C<100, non-HDL-C<130, TG<150; LDL phenotype; HDL-C ≥ 40; TG<150; and TG/HDL-C<3. METHODS: We measured ApoB, ApoAI, ultracentrifugation lipoprotein cholesterol and NMR lipoprotein particle concentration in 148 unselected primary and secondary prevention patients. RESULTS: TC/HDL-C<3 effectively discriminated subjects by LDL-P goal (F = 84.1, p<10(-6. The ATP-III very high risk composite target (LDL-C<70, nonHDL-C<100, TG<150 was also effective (F = 42.8, p<10(-5. However, the standard secondary prevention composite (LDL-C<100, non-HDL-C<130, TG<150 was also effective but yielded higher LDL-P than the very high risk composite (F = 42.0, p<10(-5 with upper 95% confidence interval of LDL-P less than 1000 nmol/L. TG<150 and TG/HDL-C<3 cutpoints both significantly discriminated subjects but the LDL-P upper 95% confidence intervals fell above goal of 1000 nmol/L (F = 15.8, p = 0.0001 and F = 9.7, p = 0.002 respectively. LDL density phenotype neared significance (F = 2.85, p = 0.094 and the HDL-C cutpoint of 40 mg/dL did not discriminate (F = 0.53, p = 0.47 alone or add discriminatory power to ATP-III targets. CONCLUSIONS: A simple composite of ATP-III very high risk lipoprotein cholesterol based treatment targets or TC/HDL-C ratio <3 most effectively identified subjects meeting the secondary prevention target level of LDL-P<1000 nmol/L, providing a potential alternative to advanced lipid testing in many clinical

  14. The influence of particle clustering on the rheological properties of highly concentrated magnetic nanofluids.

    Science.gov (United States)

    Susan-Resiga, Daniela; Socoliuc, V; Boros, T; Borbáth, Tunde; Marinica, Oana; Han, Adelina; Vékás, L

    2012-05-01

    In this paper the particle volume fraction and temperature dependence of the dynamic viscosity of highly concentrated transformer oil based magnetic nanofluids was investigated in the absence of an external magnetic field. The solid particle volume fraction dependence of the relative viscosity was found to be very well fitted by the Krieger-Dougherty formula, whence the mean ellipticity of the colloidal particles and the effective surfactant layer thickness were obtained. Using the information on the particles' size and shape statistics obtained from TEM, DLS and magnetogranulometry investigations, it was concluded that the magnetite nanoparticles agglomerate in small clusters of about 1.3 particles/cluster, due to the van der Waals interactions. The effective thickness of the oleic acid surfactant layer was estimated as about 1.4 nm, in very good agreement with the value resulted from previous SANS investigations. PMID:22134213

  15. Estimation of Collection Efficiency Depended on Feed Particle Concentration for Axial Flow Cyclone Dust Collector

    Institute of Scientific and Technical Information of China (English)

    AkiraOgawa

    1999-01-01

    A cyclone dust collector is applied in many industries.Especially the axial flow cyclone is the most simple construction and if keeps high reliability for maintenance.On the other hand,the collection efficiency of the cyclone depends not only on the inlet gas velocity but also on the feed particle concentration.The collection efficiency increases with increasing feed particle concentration.However until now the problem of how to estimate the collection efficiency depended on the feed particle concentration is remained except the investigation by Muschelknautz & Brunner[6],Therefore in this paper one of the estimate method for the collection efficiency of the axial flow cyclones is proposed .The application to the geometrically similar type of cyclone of the body diameters D1=30,50,69and 99mm showed in good agreement with the experimental results of the collection efficiencies which were described in detail in the paper by ogawa & Sugiyama[8].

  16. A model for aerosol mass concentration using an optical particle counter

    Institute of Scientific and Technical Information of China (English)

    Fang Gu; Juan Yang; Baomin Bian; Anzhi He

    2008-01-01

    A model for measuring aerosol mass concentration by an optical particle counter is presented using the conception of the average mass.In this model,to understand the meaning of the pulse height distribution of particles which is used to inverse mass concentration,the relationship among intensity distribution in the optical sensing volume,particle shape,and the pulse height distribution is discussed.To solve the instability of the equivalent factor,a novel two-step calibration method is proposed.The experimental results demonstrate that mass concentrations calculated by the model are in good agreement with those measured by a norm-referenced instrument.For samples of soot and air,the slopes of fitting lines of data points are 0.9582 and 0.9220,and the correlation coefficients are 0.9991 and 0.9965,respectively.

  17. Simple Model for Gold Nano Particles Concentration Dependence of Resonance Energy Transfer Intensity

    Science.gov (United States)

    Hoa, N. M.; Ha, C. V.; Nga, D. T.; Lan, N. T.; Nhung, T. H.; Viet, N. A.

    2016-06-01

    Gold nano particles (GNPs) concentration dependence of the energy transfer occurs between the fluorophores and GNPs is investigated. In the case of theses pairs, GNPs can enhance or quench the fluorescence of fluorophores depending upon the relative magnitudes of two energy transfer mechanisms: i) the plasmonic field enhancement at the fluorophores emission frequencies (plasmon coupled fluorescence enhancement) and ii) the localized plasmon coupled Forster energy transfer from fluorescent particles to gold particles, which quenches the fluorescence. The competition of these mechanisms is depending on the spectral overlap of fluorophores and GNPs, their relative concentration, excitation wavelength. Simple two branches surface plasmon polariton model for GNPs concentration dependence of the energy transfer is proposed. The experimental data and theoretical results confirm our findings.

  18. The concentrations of radionuclides, heavy metals, and poloychlorinated biphenyls in field mice collected from regional background areas. Revision 3

    Energy Technology Data Exchange (ETDEWEB)

    Fresquez, Philip R. [Los Alamos National Laboratory

    2016-01-21

    Field mice are effective indicators of contaminant presence. This paper reports the concentrations of various radionuclides, heavy metals, polychlorinated biphenyls, high explosives, perchlorate, and dioxin/furans in field mice (mostly deer mice) collected from regional background areas in northern New Mexico. These data, represented as the regional statistical reference level (the mean plus three standard deviations = 99% confidence level), are used to compare with data from field mice collected from areas potentially impacted by Laboratory operations, as per the Environmental Surveillance Program at Los Alamos National Laboratory.

  19. Evaluation of correlating factors between {sup 238}U concentration measured in fine and course atmospheric particles

    Energy Technology Data Exchange (ETDEWEB)

    Peixoto, Claudia Marques; Jacomino, Vanusa Maria Feliciano; Barreto, Alberto Avelar; Dias, Vagner Silva, E-mail: cmp@cdtn.b, E-mail: vmfj@cdtn.b, E-mail: aab@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Dias, Fabiana Ferrari, E-mail: fdias@cnen.gov.b [Brazilian Nuclear Energy Commission (CNEN-/MG), Pocos de Caldas, MG (Brazil). Lab. de Pocos de Caldas (LAPOC)

    2009-07-01

    Air quality is ever more important in function of the enormous proportion of human actions that have affected the environment over the last two centuries. Particulate material is one among many pollutants that can cause great risk to human health and the environment. It can be classified as: Total Suspended Particles (TSP), defined simply as particles with less than 50 mum aerodynamic diameter (one group of these particles can be inhaled and may cause health problems, while others may unfavorably affect the population's quality of life, interfering in environmental conditions and impairing normal community activities); and Inhalable Particles (PM{sub 10}), defined as those particles with less than 10 mum aerodynamic diameter. These particles penetrate the respiratory system and can reach pulmonary alveoli due to their small size, causing serious health damage. The Nuclear Technology Development Center (CDTN) has monitored air quality around its installations since 2000. CDTN's Environmental Monitoring Program (EMP) includes monitoring radioactivity levels contained in atmospheric TSP. In order to optimize its program, CDTN is carrying out a study to estimate the correlation between concentrations of particulate material measured in TSP and those measured in PM{sub 10}, PI{sub 2.5} and PI{sub 1}, as well as determination of activity concentration for each controlled radionuclide in all parts. The objective of this study is to present preliminary results and report {sup 238}U activity concentration results. (author)

  20. Explaining global surface aerosol number concentrations in terms of primary emissions and particle formation

    Directory of Open Access Journals (Sweden)

    D. V. Spracklen

    2010-05-01

    Full Text Available We synthesised observations of total particle number (CN concentration from 36 sites around the world. We found that annual mean CN concentrations are typically 300–2000 cm−3 in the marine boundary layer and free troposphere (FT and 1000–10 000 cm−3 in the continental boundary layer (BL. Many sites exhibit pronounced seasonality with summer time concentrations a factor of 2–10 greater than wintertime concentrations. We used these CN observations to evaluate primary and secondary sources of particle number in a global aerosol microphysics model. We found that emissions of primary particles can reasonably reproduce the spatial pattern of observed CN concentration (R2=0.46 but fail to explain the observed seasonal cycle (R2=0.1. The modeled CN concentration in the FT was biased low (normalised mean bias, NMB=−88% unless a secondary source of particles was included, for example from binary homogeneous nucleation of sulfuric acid and water (NMB=−25%. Simulated CN concentrations in the continental BL were also biased low (NMB=−74% unless the number emission of anthropogenic primary particles was increased or a mechanism that results in particle formation in the BL was included. We ran a number of simulations where we included an empirical BL nucleation mechanism either using the activation-type mechanism (nucleation rate, J, proportional to gas-phase sulfuric acid concentration to the power one or kinetic-type mechanism (J proportional to sulfuric acid to the power two with a range of nucleation coefficients. We found that the seasonal CN cycle observed at continental BL sites was better simulated by BL particle formation (R2=0.3 than by increasing the number emission from primary anthropogenic sources (R2=0.18. The nucleation constants that resulted in best overall match between model and observed CN concentrations were

  1. Particle Size Affects Concentration-Dependent Cytotoxicity of Chitosan Nanoparticles towards Mouse Hematopoietic Stem Cells

    Directory of Open Access Journals (Sweden)

    Siti Sarah Omar Zaki

    2015-01-01

    Full Text Available Chitosan nanoparticles (CSNPs have been extensively applied in medical and pharmaceutical fields as promising drug delivery systems. Despite that, the safety of CSNPs remains inadequate and needs further investigation, particularly on hematopoietic stem cells (HSCs. CSNPs were prepared by ionic gelation method and later were characterized for their physical characteristics (particle size and zeta potential. Cytotoxicity of CSNPs was assessed by MTT assay. Particle size was highly influenced by chitosan concentration and molecular weight (medium and high molecular weight (MMW and HMW. Higher chitosan concentration and molecular weight produced larger nanoparticles. Zeta potential of CSNPs was not significantly affected by chitosan concentrations and molecular weights used in the present study. MMW had a better stability than HMW CSNPs as their particle size and zeta potential were not significantly altered after autoclaving. Cytotoxicity of CSNPs was influenced by zeta potential and particle size. On the other hand, chitosan concentration and molecular weight indirectly influenced cytotoxicity by affecting particle size and zeta potential of CSNPs. In conclusion, cytotoxicity of CSNPs was mainly attributed to their physical characteristics and this opens a strategy to ensure the safety of CSNPs applications in stem cell technology.

  2. Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density.

    Science.gov (United States)

    Cho, Jung Sang; Lee, Jeong-Cheol; Rhee, Sang-Hoon

    2016-02-01

    In the synthesis of hydroxyapatite powders by spray pyrolysis, control of the particle size was investigated by varying the initial concentration of the precursor solution and the pyrolysis temperature. Calcium phosphate solutions (Ca/P ratio of 1.67) with a range of concentrations from 0.1 to 2.0 mol/L were prepared by dissolving calcium nitrate tetrahydrate and diammonium hydrogen phosphate in deionized water and subsequently adding nitric acid. Hydroxyapatite powders were then synthesized by spray pyrolysis at 900°C and at 1500°C, using these calcium phosphate precursor solutions, under the fixed carrier gas flow rate of 10 L/min. The particle size decreased as the precursor concentration decreased and the spray pyrolysis temperature increased. Sinterability tests conducted at 1100°C for 1 h showed that the smaller and denser the particles were, the higher the relative densities were of sintered hydroxyapatite disks formed from these particles. The practical implication of these results is that highly sinterable small and dense hydroxyapatite particles can be synthesized by means of spray pyrolysis using a low-concentration precursor solution and a high pyrolysis temperature under a fixed carrier gas flow rate. PMID:25891158

  3. RELATIVE LEVELS OF INDOOR AND OUTDOOR PARTICLE NUMBER CONCENTRATIONS IN A RESIDENTIAL BUILDING IN XI'AN

    Institute of Scientific and Technical Information of China (English)

    Yanming Kang; Ke Zhong; Shun-Cheng Lee

    2006-01-01

    The time series of indoor and outdoor particle number concentrations in a naturally ventilated residential building in Xi'an were tested simultaneously for 7 days in summer. The relationships between indoor and outdoor concentrations were examined and discussed, and linear regression analysis was employed to correlate the indoor and outdoor concentrations. The diurnal cycles of indoor and outdoor particle concentrations of different particle size ranges all showed positive correlations between indoor and outdoor number concentrations. The I/O ratios of number concentrations varied with the increase of particle size in the range of 0.89 (±0.19) to 0.99 (±0.15).

  4. Concentrations of fine, ultrafine, and black carbon particles in auto-rickshaws in New Delhi, India

    Science.gov (United States)

    Apte, Joshua, S.; Kirchstetter, Thomas W.; Reich, Alexander, H.; Deshpande, Shyam J.; Kaushik, Geetanjali; Chel, Arvind; Marshall, Julian D.; Nazaroff, William W.

    2011-08-01

    Concentrations of air pollutants from vehicles are elevated along roadways, indicating that human exposure in transportation microenvironments may not be adequately characterized by centrally located monitors. We report results from ˜180 h of real-time measurements of fine particle and black carbon mass concentration (PM 2.5, BC) and ultrafine particle number concentration (PN) inside a common vehicle, the auto-rickshaw, in New Delhi, India. Measured exposure concentrations are much higher in this study (geometric mean for ˜60 trip-averaged concentrations: 190 μg m -3 PM 2.5, 42 μg m -3 BC, 280 × 10 3 particles cm -3; GSD ˜1.3 for all three pollutants) than reported for transportation microenvironments in other megacities. In-vehicle concentrations exceeded simultaneously measured ambient levels by 1.5× for PM 2.5, 3.6× for BC, and 8.4× for PN. Short-duration peak concentrations (averaging time: 10 s), attributable to exhaust plumes of nearby vehicles, were greater than 300 μg m -3 for PM 2.5, 85 μg m -3 for BC, and 650 × 10 3 particles cm -3 for PN. The incremental increase of within-vehicle concentration above ambient levels—which we attribute to in- and near-roadway emission sources—accounted for 30%, 68% and 86% of time-averaged in-vehicle PM 2.5, BC and PN concentrations, respectively. Based on these results, we estimate that one's exposure during a daily commute by auto-rickshaw in Delhi is as least as large as full-day exposures experienced by urban residents of many high-income countries. This study illuminates an environmental health concern that may be common in many populous, low-income cities.

  5. Gas-particle interactions above a Dutch heathland: II. Concentrations and surface exchange fluxes of atmospheric particles

    Directory of Open Access Journals (Sweden)

    E. Nemitz

    2004-01-01

    Full Text Available Size-dependent particle number fluxes measured by eddy-covariance (EC and continuous fluxes of ammonium (NH4+ measured with the aerodynamic gradient method (AGM are reported for a Dutch heathland. Daytime deposition velocities (Vd by EC with peak values of 5 to 10 mm s-1 increased with particle diameter (dp over the range 0.1–0.5 µm, and are faster than predicted by current models. With a mean Vd of 2.0 mm s-1 (daytime: 2.7; night-time 0.8 mm s-1 NH4+ fluxes by AGM are overall in agreement with former measurements and NH4+-N dry deposition amounts to 20% of the dry input of NH3-N over the measurement period. These surface exchange fluxes are analyzed together with simultaneous gas-phase flux measurements for indications of gas-particle interactions. On warm afternoons the apparent fluxes of acids and aerosol above the heathland showed several coinciding anomalies, all of which are consistent with NH4+ evaporation during deposition: (i canopy resistances for HNO3 and HCl of up to 100 s m-1, (ii simultaneous particle emission of small particles (DpDp>0.18 µm, (iii NH4+ deposition faster than derived from size-distributions and size-segregated EC particle fluxes. These observations coincide with the observations of (i surface concentration products of NH3 and HNO3 well below the thermodynamic equilibrium value and (ii Damköhler numbers that indicate chemical conversion to be sufficiently fast to modify exchange fluxes. The measurements imply a removal rate of volatile NH4+ of 3−30×10-6 s-1 averaged over the 1 km boundary-layer, while NH3 deposition is underestimated by typically 20 ng m-2 s-1 (28% and flux reversal may occur.

  6. Extinction of polarized light in ferrofluids with different magnetic particle concentrations

    Science.gov (United States)

    Socoliuc, V.; Popescu, L. B.

    2012-01-01

    The magnetic field intensity and nanoparticle concentration dependence of the polarized light extinction in a ferrofluid made of magnetite particles stabilized with technical grade oleic acid dispersed in transformer oil was experimentally investigated. The magnetically induced optical anisotropy, i.e. the dichroism divided by concentration, was found to decrease with increasing sample concentration from 2% to 8%. The magnetically induced change in the optical extinction of light polarized at 54.74° with respect to the magnetic field direction was found to be positive for the less concentrated sample (2%) and negative for the samples with 4% and 8% magnetic nanoparticle concentrations, the more negative the higher the concentration and field intensity. Based on the theoretically proven fact [11] that the particle orientation mechanism has no effect on the extinction of light polarized at 54.74° with respect to the field direction, we analyzed the experimental findings in the frames of the agglomeration and long-range pair correlations theories for the magnetically induced optical anisotropy in ferrofluids. We developed a theoretical model in the approximation of single scattering for the optical extinction coefficient of a ferrofluid with magnetically induced particle agglomeration. The model predicts the existence of a polarization independent component of the optical extinction coefficient that is experimentally measurable at 54.74° polarization angle. The change in the optical extinction of light polarized at 54.74° is positive if only the formation of straight n-particle chains is considered and may become negative in the hypothesis that the longer chains degenerate to more isotropic structures (polymer-like coils, globules or bundles of chains). The model for the influence on the light absorption of the long-range pair correlations, published elsewhere, predicts that the change in the optical extinction of light polarized at 54.74° is always negative, the

  7. Preferential concentration of inertial sub-kolmogorov particles. The roles of mass loading of particles, Stokes and Reynolds numbers

    CERN Document Server

    Sumbekova, Sholpan; Aliseda, Alberto; Bourgoin, Mickael

    2016-01-01

    Turbulent flows laden with inertial particles present multiple open questions and are a subject of great interest in current research. Due to their higher density compared to the carrier fluid, inertial particles tend to form high concentration regions, i.e. clusters, and low concentration regions, i.e. voids, due to the interaction with the turbulence. In this work, we present an experimental investigation of the clustering phenomenon of heavy sub-Kolmogorov particles in homogeneous isotropic turbulent flows. Three control parameters have been varied over significant ranges: $Re_{\\lambda} \\in [170 - 450]$, $St\\in [0.1 - 5]$ and volume fraction $\\phi_v\\in [2\\times 10^{-6} - 2\\times 10^{-5}]$. The scaling of clustering characteristics, such as the distribution of Vorono\\"i areas and the dimensions of cluster and void regions, with the three parameters are discussed. In particular, for the polydispersed size distributions considered here, clustering is found to be enhanced strongly (quasi-linearly) by $Re_{\\lam...

  8. A concentrated solar cavity absorber with direct heat transfer through recirculating metallic particles

    Science.gov (United States)

    Sarker, M. R. I.; Saha, Manabendra; Beg, R. A.

    2016-07-01

    A recirculating flow solar particle cavity absorber (receiver) is modeled to investigate the flow behavior and heat transfer characteristics of a novel developing concept. It features a continuous recirculating flow of non-reacting metallic particles (black silicon carbide) with air which are used as a thermal enhancement medium. The aim of the present study is to numerically investigate the thermal behavior and flow characteristics of the proposed concept. The proposed solar particle receiver is modeled using two phase discrete particle model (DPM), RNG k-flow model and discrete ordinate (DO) radiation model. Numerical analysis is carried out considering a solar receiver with only air and the mixture of non-reacting particles and air as a heat transfer as well as heat carrying medium. The parametric investigation is conducted considering the incident solar flux on the receiver aperture and changing air flow rate and recirculation rate inside the receiver. A stand-alone feature of the recirculating flow solar particle receiver concept is that the particles are directly exposed to concentrated solar radiation monotonously through recirculating flow inside the receiver and results in efficient irradiation absorption and convective heat transfer to air that help to achieve high temperature air and consequently increase in thermal efficiency. This paper presents, results from the developed concept and highlights its flow behavior and potential to enhance the heat transfer from metallic particles to air by maximizing heat carrying capacity of the heat transfer medium. The imposed milestones for the present system will be helpful to understand the radiation absorption mechanism of the particles in a recirculating flow based receiver, the thermal transport between the particles, the air and the cavity, and the fluid dynamics of the air and particle in the cavity.

  9. Extinction of polarized light in ferrofluids with different magnetic particle concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Socoliuc, V., E-mail: vsocoliuc@gmail.com [' Petru Poni' Institute of Macromolecular Chemistry, Iasi, Romania, 41A Grigore Ghica Voda Alley, 700487 Iasi (Romania); Lab. Magnetic Fluids, Center for Fundamental and Advanced Technical Research, Romanian Academy-Timisoara Branch, Bv.M. Viteazu 24, Timisoara RO-300223 (Romania); Popescu, L.B. [Institute for Space Sciences, Atomistilor 409, Magurele 077125 (Romania)

    2012-01-15

    The magnetic field intensity and nanoparticle concentration dependence of the polarized light extinction in a ferrofluid made of magnetite particles stabilized with technical grade oleic acid dispersed in transformer oil was experimentally investigated. The magnetically induced optical anisotropy, i.e. the dichroism divided by concentration, was found to decrease with increasing sample concentration from 2% to 8%. The magnetically induced change in the optical extinction of light polarized at 54.74{sup o} with respect to the magnetic field direction was found to be positive for the less concentrated sample (2%) and negative for the samples with 4% and 8% magnetic nanoparticle concentrations, the more negative the higher the concentration and field intensity. Based on the theoretically proven fact that the particle orientation mechanism has no effect on the extinction of light polarized at 54.74{sup o} with respect to the field direction, we analyzed the experimental findings in the frames of the agglomeration and long-range pair correlations theories for the magnetically induced optical anisotropy in ferrofluids. We developed a theoretical model in the approximation of single scattering for the optical extinction coefficient of a ferrofluid with magnetically induced particle agglomeration. The model predicts the existence of a polarization independent component of the optical extinction coefficient that is experimentally measurable at 54.74{sup o} polarization angle. The change in the optical extinction of light polarized at 54.74{sup o} is positive if only the formation of straight n-particle chains is considered and may become negative in the hypothesis that the longer chains degenerate to more isotropic structures (polymer-like coils, globules or bundles of chains). The model for the influence on the light absorption of the long-range pair correlations, published elsewhere, predicts that the change in the optical extinction of light polarized at 54.74{sup o} is

  10. Evaluation and modeling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki ─ Part II: Aerosol measurements within the SAPPHIRE project

    Directory of Open Access Journals (Sweden)

    A. Karppinen

    2007-08-01

    Full Text Available This study presents an evaluation and modeling exercise of the size fractionated aerosol particle number concentrations measured nearby a major road in Helsinki during 23 August–19 September 2003 and 14 January–11 February 2004. The available information also included electronic traffic counts, on-site meteorological measurements, and urban background particle number size distribution measurement. The ultrafine particle (UFP, diameter<100 nm number concentrations at the roadside site were approximately an order of magnitude higher than those at the urban background site during daytime and downwind conditions. Both the modal structure analysis of the particle number size distributions and the statistical correlation between the traffic density and the UFP number concentrations indicate that the UFP were evidently from traffic related emissions. The modeling exercise included the evolution of the particle number size distribution nearby the road during downwind conditions. The model simulation results revealed that the evaluation of the emission factors of aerosol particles might not be valid for the same site during different time.

  11. Ratios of total suspended solids to suspended sediment concentrations by particle size

    Science.gov (United States)

    Selbig, W.R.; Bannerman, R.T.

    2011-01-01

    Wet-sieving sand-sized particles from a whole storm-water sample before splitting the sample into laboratory-prepared containers can reduce bias and improve the precision of suspended-sediment concentrations (SSC). Wet-sieving, however, may alter concentrations of total suspended solids (TSS) because the analytical method used to determine TSS may not have included the sediment retained on the sieves. Measuring TSS is still commonly used by environmental managers as a regulatory metric for solids in storm water. For this reason, a new method of correlating concentrations of TSS and SSC by particle size was used to develop a series of correction factors for SSC as a means to estimate TSS. In general, differences between TSS and SSC increased with greater particle size and higher sand content. Median correction factors to SSC ranged from 0.29 for particles larger than 500m to 0.85 for particles measuring from 32 to 63m. Great variability was observed in each fraction-a result of varying amounts of organic matter in the samples. Wide variability in organic content could reduce the transferability of the correction factors. ?? 2011 American Society of Civil Engineers.

  12. Characterization study of cesium concentrated particles in the soils near the Fukushima Daiichi nuclear power plant

    Science.gov (United States)

    Satou, Yukihiko; Sueki, Keisuke; Sasa, Kimikazu; Adachi, Kouji; Igarashi, Yasuhito

    2015-04-01

    Radionuclides from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident contaminated a vast area. Two types of contamination, spread and spot types, were observed in soils with autoradiography using an imaging plate. Other samples such as dust filters, vegetation, X-ray films, and so on, also indicate the spot type contamination in the early stage of the FDNPP accident. The source of spot type contamination is well known as hot particles at the Chernobyl Nuclear Power Plant (ChNPP) accident in 1986. Hot particles were divided into two groups, fuel hot particles and fission product particles, and they were emitted directly from reactor core with phreatic explosion and fire. In contrast, the official reports of the FDNPP accident did not conforme core explosion. In addition, the emitted total amount of Uranium was very few (Yamamoto et al., 2014). Thus, the spot type contaminations were not identified as the same of hot particles yet. Therefore, the present study aimed to pick up and identify the spot contaminations in soils. Surface soil samples were collected at 20 km northwest from the FDNPP in June 2013. Soils were spread in plastic bags for autoradiography with imaging plate analysis. Then, the soil particles were collected on a sticky carbon tape and analyzed by SEM-EDS to detect radioactive particles. Finally, particles were confirmed to contain photo peaks in the γ-spectrum by a germanium semiconductor detector. Four radioactive particles were isolated from the soil samples in the present study. Detected γ-ray emission radionuclides were only Cs-134 and Cs-137. The X-ray spectra on the SEM-EDS of all particles showed a Cs peak as well as O, Fe, Zn, and Rb peaks, and these elements were distributed uniformly within the particles. In addition, uniform distribution of Si was also shown. Moreover, U was detected from one of the particles, but U concentration was very low and existed locally in the particle. These characters are very similar to previous

  13. Contribution of carbonaceous material to cloud condensation nuclei concentrations in European background (Mt. Sonnblick) and urban (Vienna) aerosols

    Science.gov (United States)

    Hitzenberger, R.; Berner, A.; Giebl, H.; Kromp, R.; Larson, S. M.; Rouc, A.; Koch, A.; Marischka, S.; Puxbaum, H.

    During four intensive measurement campaigns (two on Mt. Sonnblick, European background aerosol, and two in Vienna, urban aerosol), cloud condensation nuclei (CCN) were measured at supersaturations of 0.5%. Impactor measurements of the mass size distribution in the size range 0.1-10 μm were performed and later analyzed for Cl -, NO -3, SO 2-4, Na +, NH +4, K +, Ca 2+ and Mg 2+ by ion chromatography, for total carbon (TC) using a combustion method, and for black carbon (BC) by an optical method (integrating sphere). Organic carbon (OC) was defined as the difference between TC (minus carbonate carbon) and BC. At all sites, the mass fraction of BC in the submicron aerosol was comparable (4-5%). CCN concentrations on Mt. Sonnblick were found to be 10-30% of those measured in Vienna, although high Mt. Sonnblick concentrations were comparable to low Vienna concentrations (around 800 cm -3). The contribution of organic material was estimated from the mass concentrations of the chemical species sampled on the impactor stage with the lowest cut point (0.1-0.215 μm aerodynamic equivalent diameter). On Mt. Sonnblick, TC material contributed 11% to the total mass in fall 1995, and 67% in summer 1996, while the OC fraction was 6 and 61%. The combined electrolytes and mineral material contributed 18 and 16% in fall and summer. During the Vienna spring campaign, the contributions of OC and electrolytes to the total mass concentration in this size range were 48 and 36%, respectively.

  14. Concentrations and Sources of Airborne Particles in a Neonatal Intensive Care Unit

    Science.gov (United States)

    Licina, Dusan; Bhangar, Seema; Brooks, Brandon; Baker, Robyn; Firek, Brian; Tang, Xiaochen; Morowitz, Michael J.; Banfield, Jillian F.; Nazaroff, William W.

    2016-01-01

    Premature infants in neonatal intensive care units (NICUs) have underdeveloped immune systems, making them susceptible to adverse health consequences from air pollutant exposure. Little is known about the sources of indoor airborne particles that contribute to the exposure of premature infants in the NICU environment. In this study, we monitored the spatial and temporal variations of airborne particulate matter concentrations along with other indoor environmental parameters and human occupancy. The experiments were conducted over one year in a private-style NICU. The NICU was served by a central heating, ventilation and air-conditioning (HVAC) system equipped with an economizer and a high-efficiency particle filtration system. The following parameters were measured continuously during weekdays with 1-min resolution: particles larger than 0.3 μm resolved into 6 size groups, CO2 level, dry-bulb temperature and relative humidity, and presence or absence of occupants. Altogether, over sixteen periods of a few weeks each, measurements were conducted in rooms occupied with premature infants. In parallel, a second monitoring station was operated in a nearby hallway or at the local nurses’ station. The monitoring data suggest a strong link between indoor particle concentrations and human occupancy. Detected particle peaks from occupancy were clearly discernible among larger particles and imperceptible for submicron (0.3–1 μm) particles. The mean indoor particle mass concentrations averaged across the size range 0.3–10 μm during occupied periods was 1.9 μg/m3, approximately 2.5 times the concentration during unoccupied periods (0.8 μg/m3). Contributions of within-room emissions to total PM10 mass in the baby rooms averaged 37–81%. Near-room indoor emissions and outdoor sources contributed 18–59% and 1–5%, respectively. Airborne particle levels in the size range 1–10 μm showed strong dependence on human activities, indicating the importance of indoor

  15. Concentrations and Sources of Airborne Particles in a Neonatal Intensive Care Unit.

    Directory of Open Access Journals (Sweden)

    Dusan Licina

    Full Text Available Premature infants in neonatal intensive care units (NICUs have underdeveloped immune systems, making them susceptible to adverse health consequences from air pollutant exposure. Little is known about the sources of indoor airborne particles that contribute to the exposure of premature infants in the NICU environment. In this study, we monitored the spatial and temporal variations of airborne particulate matter concentrations along with other indoor environmental parameters and human occupancy. The experiments were conducted over one year in a private-style NICU. The NICU was served by a central heating, ventilation and air-conditioning (HVAC system equipped with an economizer and a high-efficiency particle filtration system. The following parameters were measured continuously during weekdays with 1-min resolution: particles larger than 0.3 μm resolved into 6 size groups, CO2 level, dry-bulb temperature and relative humidity, and presence or absence of occupants. Altogether, over sixteen periods of a few weeks each, measurements were conducted in rooms occupied with premature infants. In parallel, a second monitoring station was operated in a nearby hallway or at the local nurses' station. The monitoring data suggest a strong link between indoor particle concentrations and human occupancy. Detected particle peaks from occupancy were clearly discernible among larger particles and imperceptible for submicron (0.3-1 μm particles. The mean indoor particle mass concentrations averaged across the size range 0.3-10 μm during occupied periods was 1.9 μg/m3, approximately 2.5 times the concentration during unoccupied periods (0.8 μg/m3. Contributions of within-room emissions to total PM10 mass in the baby rooms averaged 37-81%. Near-room indoor emissions and outdoor sources contributed 18-59% and 1-5%, respectively. Airborne particle levels in the size range 1-10 μm showed strong dependence on human activities, indicating the importance of indoor

  16. A Cascade Model for Particle Concentration and Enstrophy in Fully Developed Turbulence with Mass Loading Feedback

    CERN Document Server

    Hogan, Robert C

    2007-01-01

    A cascade model is described based on multiplier distributions determined from 3D direct numerical simulations (DNS) of turbulent particle laden flows, which include two-way coupling between the phases at global mass loadings equal to unity. The governing Eulerian equations are solved using pseudo-spectral methods on up to 512**3 computional grid points. DNS results for particle concentration and enstrophy at Taylor microscale Reynolds numbers in the range 34 - 170 were used to directly determine multiplier distributions (PDFs) on spatial scales 3 times the Kolmogorov length scale. The width of the PDFs, which is a measure of intermittency, decreases with increasing mass loading within the local region where the multipliers are measured. The functional form of this dependence is not sensitive to Reynolds numbers in the range considered. A partition correlation probability is included in the cascade model to account for the observed spatial anticorrelation between particle concentration and enstrophy. Joint pr...

  17. Heating Characteristics of Transformer Oil-Based Magnetic Fluids of Different Magnetic Particle Concentrations

    Science.gov (United States)

    Skumiel, A.; Hornowski, T.; Józefczak, A.

    2011-04-01

    The heating ability of mineral oil-based magnetic fluids with different magnetic particle concentrations is studied. The calorimetric measurements were carried out in an alternating magnetic field of 500 A · m-1 to 2500 A · m-1 amplitude and of 1500 kHz frequency. The revealed H n law-type dependence of the temperature increase rate, (d T/d t) t=0, on the amplitude of the magnetic field indicates the presence of superparamagnetic and partially ferromagnetic particles in the tested samples since n > 2. The specific absorption rate (SAR) defined as the rate of energy absorption per unit mass increases with a decrease of the volume fraction of the dispersed phase. This can be explained by the formation of aggregates in the samples with a higher concentration of magnetic particles.

  18. The Effect of Particle Concentration on the Heating Rate of Ferrofluids for Magnetic Hyperthermia

    Directory of Open Access Journals (Sweden)

    Malaescu I.

    2015-12-01

    Full Text Available The complex magnetic susceptibility χ(f = χ′(f - i χ″(f, of a ferrofluid sample with magnetite particles dispersed in kerosene and stabilized with oleic acid, over the range 0.1 GHz to 6 GHz, was determined. The initial sample has been successively diluted with kerosene (with a dilution rate of 2/3, thus obtaining further three samples. Using the complex magnetic susceptibility measurements of each sample, the frequency field and particle concentration dependencies of the heating rate of the ferrofluid samples, were analyzed. The results show the possibility of using the heating rate of ferrofluid samples with different particle concentrations, in hyperthermia applications.

  19. Particle enhanced foam flow in porous media near the critical micelle concentration

    NARCIS (Netherlands)

    Thorat, R.R.

    2016-01-01

    This thesis was performed in the framework of ErasmusMundus EU-INDIA scholarship programme. The main goal is to elucidate particle enhanced foam flow (surfactant water and nitrogen gas) in porous media near the critical micelle concentration. The thesis is divided in four parts: in the first part th

  20. Probabilistic Preparation of N-particle Cat States via Entanglement Swapping and Entanglement Concentration

    Institute of Scientific and Technical Information of China (English)

    姚春梅; 李敏; 叶柳; 郭光灿

    2002-01-01

    We discuss two different schemes for the probabilistic preparation of N-particle cat states using pure multiparticle entangled states via entanglement swapping and entanglement concentration. At the centre of distribution A,Alice performs all of the operations required to achieve our goal.

  1. Particle size distribution and PAH concentrations of incense smoke in a combustion chamber.

    Science.gov (United States)

    Yang, Chi-Ru; Lin, Ta-Chang; Chang, Feng-Hsiang

    2007-01-01

    The particle size distribution and the concentrations of polycyclic aromatic hydrocarbons (PAHs) in incense smoke were studied using a custom-designed combustion chamber. Among the nine types of incense investigated, the particle and the total PAH emission factors varied significantly. The average mass median aerodynamic diameter (MMAD) of the smoke aerosol was 262+/-49nm, which positively correlated to particle emission factor (mg/stick, pincense smoke may pose potential health risk. Experiments show that each lowered percentage of total carbon content in the raw incense helped decrease the particle emission factor by 2.6mg/g-incense, and the reduction of S-PAH emission factor ranged from 8.7 to 26% when the carbon content was lowered from 45 to 40%.

  2. Cascade model for particle concentration and enstrophy in fully developed turbulence with mass-loading feedback.

    Science.gov (United States)

    Hogan, R C; Cuzzi, J N

    2007-05-01

    A cascade model is described based on multiplier distributions determined from three-dimensional (3D) direct numerical simulations (DNS) of turbulent particle laden flows, which include two-way coupling between the phases at global mass loadings equal to unity. The governing Eulerian equations are solved using psuedospectral methods on up to 512(3) computional grid points. DNS results for particle concentration and enstrophy at Taylor microscale Reynolds numbers in the range 34-170 were used to directly determine multiplier distributions on spatial scales three times the Kolmogorov length scale. The multiplier probability distribution functions (PDFs) are well characterized by the beta distribution function. The width of the PDFs, which is a measure of intermittency, decreases with increasing mass loading within the local region where the multipliers are measured. The functional form of this dependence is not sensitive to Reynolds numbers in the range considered. A partition correlation probability is included in the cascade model to account for the observed spatial anticorrelation between particle concentration and enstrophy. Joint probability distribution functions of concentration and enstrophy generated using the cascade model are shown to be in excellent agreement with those derived directly from our 3D simulations. Probabilities predicted by the cascade model are presented at Reynolds numbers well beyond what is achievable by direct simulation. These results clearly indicate that particle mass loading significantly reduces the probabilities of high particle concentration and enstrophy relative to those resulting from unloaded runs. Particle mass density appears to reach a limit at around 100 times the gas density. This approach has promise for significant computational savings in certain applications.

  3. Classical and quantum dynamics of a charged scalar particle in a background of two counterpropagating plane waves

    CERN Document Server

    King, B

    2016-01-01

    We consider a scalar particle in a background formed by two counter-propagating plane waves. Two cases are studied: i) dynamics at a magnetic node and ii) zero initial transverse canonical momentum. The Lorentz and Klein-Gordon equations are solved for these cases and approximations analysed. For the magnetic node solution (homogeneous, time-dependent electric field), the modified Volkov wavefunction which arises from a high-energy approximation is found to be inaccurate for all energies and the solution itself unstable when photon emission (nonlinear Compton scattering) is included. For the zero initial transverse canonical momentum case, in both quantum and classical cases, forbidden parameter regimes, absent in the plane wave model, are identified.

  4. Isotropic diffuse and extragalactic $\\gamma$-ray background: emission from extragalactic sources vs dark matter annihilating particles

    CERN Document Server

    ,

    2016-01-01

    The isotropic diffuse $\\gamma$-ray background (IGRB) has been detected by various experiments and recently the Fermi-LAT Collaboration has precisely measured its spectrum in a wide energy range. The origin of the IGRB is still unclear and we show in this paper the significative improvements that have been done, thanks to the new Fermi-LAT catalogs, to solve this mystery. We demonstrate that the $\\gamma$-ray intensity and spectrum of the IGRB is fully consistent with the unresolved emission from extragalactic point sources, namely Active Galactic Nuclei and Star Forming Galaxies. We show also that the IGRB can be employed to derive sever constraints for the $\\gamma$-ray emission from diffuse processes such as annihilation of Dark Matter (DM) particles. Our method is able to provide low bounds for the thermal annihilation cross section for a wide range of DM masses.

  5. Investigation of Aerosol Surface Area Estimation from Number and Mass Concentration Measurements: Particle Density Effect

    Science.gov (United States)

    Ku, Bon Ki; Evans, Douglas E.

    2015-01-01

    For nanoparticles with nonspherical morphologies, e.g., open agglomerates or fibrous particles, it is expected that the actual density of agglomerates may be significantly different from the bulk material density. It is further expected that using the material density may upset the relationship between surface area and mass when a method for estimating aerosol surface area from number and mass concentrations (referred to as “Maynard’s estimation method”) is used. Therefore, it is necessary to quantitatively investigate how much the Maynard’s estimation method depends on particle morphology and density. In this study, aerosol surface area estimated from number and mass concentration measurements was evaluated and compared with values from two reference methods: a method proposed by Lall and Friedlander for agglomerates and a mobility based method for compact nonspherical particles using well-defined polydisperse aerosols with known particle densities. Polydisperse silver aerosol particles were generated by an aerosol generation facility. Generated aerosols had a range of morphologies, count median diameters (CMD) between 25 and 50 nm, and geometric standard deviations (GSD) between 1.5 and 1.8. The surface area estimates from number and mass concentration measurements correlated well with the two reference values when gravimetric mass was used. The aerosol surface area estimates from the Maynard’s estimation method were comparable to the reference method for all particle morphologies within the surface area ratios of 3.31 and 0.19 for assumed GSDs 1.5 and 1.8, respectively, when the bulk material density of silver was used. The difference between the Maynard’s estimation method and surface area measured by the reference method for fractal-like agglomerates decreased from 79% to 23% when the measured effective particle density was used, while the difference for nearly spherical particles decreased from 30% to 24%. The results indicate that the use of

  6. Associations of PM2.5 and black carbon concentrations with traffic, idling, background pollution, and meteorology during school dismissals.

    Science.gov (United States)

    Richmond-Bryant, J; Saganich, C; Bukiewicz, L; Kalin, R

    2009-05-01

    An air quality study was performed outside a cluster of schools in the East Harlem neighborhood of New York City. PM(2.5) and black carbon concentrations were monitored using real-time equipment with a one-minute averaging interval. Monitoring was performed at 1:45-3:30 PM during school days over the period October 31-November 17, 2006. The designated time period was chosen to capture vehicle emissions during end-of-day dismissals from the schools. During the monitoring period, minute-by-minute volume counts of idling and passing school buses, diesel trucks, and automobiles were obtained. These data were transcribed into time series of number of diesel vehicles idling, number of gasoline automobiles idling, number of diesel vehicles passing, and number of automobiles passing along the block adjacent to the school cluster. Multivariate regression models of the log-transform of PM(2.5) and black carbon (BC) concentrations in the East Harlem street canyon were developed using the observation data and data from the New York State Department of Environmental Conservation on meteorology and background PM(2.5). Analysis of variance was used to test the contribution of each covariate to variability in the log-transformed concentrations as a means to judge the relative contribution of each covariate. The models demonstrated that variability in background PM(2.5) contributes 80.9% of the variability in log[PM(2.5)] and 81.5% of the variability in log[BC]. Local traffic sources were demonstrated to contribute 5.8% of the variability in log[BC] and only 0.43% of the variability in log[PM(2.5)]. Diesel idling and passing were both significant contributors to variability in log[BC], while diesel passing was a significant contributor to log[PM(2.5)]. Automobile idling and passing did not contribute significant levels of variability to either concentration. The remainder of variability in each model was explained by temperature, along-canyon wind, and cross-canyon wind, which were

  7. Jamming, Self-Filtration and Cake Growth in Concentrated Particle Suspensions

    Science.gov (United States)

    Guo, Youjing; Li, Shoubo; Yang, Donglei; Mi, Yongli; Wang, Xiaorong

    2015-03-01

    We study the flows of concentrated particle suspensions driven through a circular orifice. Above a critical concentration, a jammed structure (i.e., quasi-solid sphere) often forms in the flow and at the entrance of the geometrical constriction. Once occurred this jammed structure grows fast as time t passes and produces a reduction in the solid concentration downstream. Our analysis shows that a combination of the particle jamming, the self-filtration, and the cake-formation with the flow passing through the pores of the jammed solid is responsible for the occurrence of such phenomena. Based on this mechanism, we establish a mathematical model to show how the jammed structure is propagated. Our results suggest that the size D of the jammed structure in this case is proportional to a 1/3 power of the time t. Experiments also support this conclusion.

  8. Power law relation between particle concentrations and their sizes in the blood plasma

    Science.gov (United States)

    Kirichenko, M. N.; Chaikov, L. L.; Zaritskii, A. R.

    2016-08-01

    This work is devoted to the investigation of sizes and concentrations of particles in blood plasma by dynamic light scattering (DLS). Blood plasma contains many different proteins and their aggregates, microparticles and vesicles. Their sizes, concentrations and shapes can give information about donor's health. Our DLS study of blood plasma reveals unexpected dependence: with increasing of the particle sizes r (from 1 nm up to 1 μm), their concentrations decrease as r-4 (almost by 12 orders). We found also that such dependence was repeated for model solution of fibrinogen and thrombin with power coefficient is -3,6. We believe that this relation is a fundamental law of nature that shows interaction of proteins (and other substances) in biological liquids.

  9. Aerosol particle and organic vapor concentrations at industrial work sites in Malaysia.

    Science.gov (United States)

    Armstrong, R W; Rood, M J; Sani, S; Mohamed, M; Rashid, M; Jab, A T; Landsberger, S

    2001-01-01

    The objective of this study was to establish baseline data about air pollutants potentially related to nasopharyngeal carcinoma (NPC) in the Federal Territory and Selangor, Malaysia. During 1991-1993, ambient air quality was monitored at 42 work sites representing ten industrial sectors: adhesive manufacturing, foundries, latex processing, metalworking, plywood/veneer milling, ricemilling, rubber tire manufacturing, sawmilling, shoemaking, and textile related industries. At each work site, aerosol particle size distributions and concentrations of formaldehyde, benzene, toluene, isopropyl alcohol, and furfural were measured. Mean aerosol particle concentrations ranged from 61 micrograms/m3 in foundries to 5,578 micrograms/m3 in ricemills, with five industries (adhesives, metalworking, ricemilling, sawmilling, and shoemaking) exceeding the US EPA 24-hr ambient air standard for PM-10. Formaldehyde concentrations exceeded the threshold limit value (TLV) in adhesives factories. Other vapours and elements measured were well below TLVs. PMID:12109256

  10. Background concentrations of heavy metals in aquatic bryophytes used for biomonitoring in basaltic areas (a case study from central France)

    Energy Technology Data Exchange (ETDEWEB)

    Samecka-Cymerman, A. [Wroclaw Univ. (Poland). Dept. of Ecology and Nature Protection; Kempers, A.J. [Nijmegen Univ. (Netherlands). Dept. of Aquatic Ecology and Biogeology

    1999-12-01

    Studies were made of the aquatic bryophytes Fontinalis antipyretica Hedw., Plathypnidium rusciforme (Neck.)Fleisch and Chiloscyphus sp. (Hoffm.)Dum. from streams embedded in basaltic rocks (Le Puy, central France). Water from these streams possessed elevated levels of Cu, Zn, Sr, V, Ba, Ni and Co, reflecting the geochemistry of the basalts, a basic type of igneous rocks containing elevated levels of these elements. The concentration of elements in bryophytes is correlated to the chemical composition of water of their sampling sites. Contents of trace elements in plants were higher than background values. The elevated levels of these elements possibly caused disturbances in the ionic equilibrium within the bryophytes. The molar ratio between contents of Ca and Mg in water (from 0.44 to 1) was different from that typical for natural water. (orig.)

  11. Temperature-dependent accumulation mode particle and cloud nuclei concentrations from biogenic sources during WACS 2010

    Directory of Open Access Journals (Sweden)

    L. Ahlm

    2012-10-01

    Full Text Available Submicron aerosol particles collected simultaneously at the mountain peak (2182 m a.s.l. and at a forested mid-mountain site (1300 m a.s.l. on Whistler Mountain, British Columbia, Canada, during June and July 2010 were analyzed by Fourier transform infrared (FTIR spectroscopy for quantification of organic functional groups. Positive matrix factorization (PMF was applied to the FTIR spectra. Three PMF factors associated with (1 combustion, (2 biogenics, and (3 vegetative detritus, were identified at both sites. The biogenic factor was correlated with both temperature and several volatile organic compounds (VOCs. The combustion factor dominated the submicron particle mass during the beginning of the campaign when the temperature was lower and advection was from the Vancouver area, but as the temperature started to rise in early July the biogenic factor came to dominate as a result of increased emissions of biogenic VOCs and thereby increased formation of secondary organic aerosol (SOA. On average, the biogenic factor represented 69% and 49% of the submicron organic particle mass at Whistler Peak and at the mid-mountain site, respectively. The lower fraction at the mid-mountain site was a result of more vegetative detritus there, and also higher influence from local combustion sources.

    The biogenic factor was strongly correlated (r ~ 0.9 to number concentration of particles with diameter (Dp> 100 nm, whereas the combustion factor was better correlated to number concentration of particles with Dp < 100 nm (r~ 0.4. The number concentration of cloud condensation nuclei (CCN was correlated (r ~ 0.7 to the biogenic factor for supersaturations (S of 0.2% or higher, which indicates that particle condensational growth from biogenic vapors was an important factor in controlling the CCN concentration for clouds where S≥0.2%. Both the number concentration of particles with

  12. Temperature-dependent accumulation mode particle and cloud nuclei concentrations from biogenic sources during WACS 2010

    Directory of Open Access Journals (Sweden)

    L. Ahlm

    2013-03-01

    Full Text Available Submicron aerosol particles collected simultaneously at the mountain peak (2182 m a.s.l. and at a forested mid-mountain site (1300 m a.s.l. on Whistler Mountain, British Columbia, Canada, during June and July 2010 were analyzed by Fourier transform infrared (FTIR spectroscopy for quantification of organic functional groups. Positive matrix factorization (PMF was applied to the FTIR spectra. Three PMF factors associated with (1 combustion, (2 biogenics, and (3 vegetative detritus were identified at both sites. The biogenic factor was correlated with both temperature and several volatile organic compounds (VOCs. The combustion factor dominated the submicron particle mass during the beginning of the campaign, when the temperature was lower and advection was from the Vancouver area, but as the temperature started to rise in early July, the biogenic factor came to dominate as a result of increased emissions of biogenic VOCs, and thereby increased formation of secondary organic aerosol (SOA. On average, the biogenic factor represented 69% and 49% of the submicron organic particle mass at Whistler Peak and at the mid-mountain site, respectively. The lower fraction at the mid-mountain site was a result of more vegetative detritus there, and also higher influence from local combustion sources. The biogenic factor was strongly correlated (r~0.9 to number concentration of particles with diameter (Dp> 100 nm, whereas the combustion factor was better correlated to number concentration of particles with Dpr~0.4. The number concentration of cloud condensation nuclei (CCN was correlated (r~0.7 to the biogenic factor for supersaturations (S of 0.2% or higher, which indicates that particle condensational growth from biogenic vapors was an important factor in controlling the CCN concentration for clouds where S≥0.2%. Both the number concentration of particles with Dp>100 nm and numbers of CCN for S≥0.2% were correlated to temperature. Considering the biogenic

  13. Influence of particles shape on the vertical profile of blowing snow concentration

    Science.gov (United States)

    Vionnet, Vincent; Trouvilliez, Alexandre; Naaim-Bouvet, Florence; Guyomarc'h, Gilbert

    2013-04-01

    In alpine regions, blowing snow events strongly influence the temporal and spatial evolution of the snow cover throughout the winter season. In Antarctica, blowing snow is an essential surface mass balance process and plays a non-negligible role in the annual accumulation. The vertical profile of blowing snow concentration determines the quantity of snow transported in turbulent suspension. A power law is often used to represent this vertical profile. It serves as an analytical solution representing an equilibrium between vertical turbulent diffusion and gravitational settling. In this work, we study how the exponent of the power law depends on the type of transported particles. Vertical profiles of blowing snow concentration have been collected at the experimental site of Col du Lac Blanc (French Alps) in 2011 and 2012 and near the research station of Cap Prud'homme (Antarctica) in 2010 and 2011. We used mechanical gauges (butterfly nets) and optical devices (Snow Particles Counters). Profiles collected during blowing snow events with precipitation have been corrected to account for the contribution of snowfall. Results show that profiles collected during blowing snow without snowfall differ from the corrected profiles collected during snowfall. At a given wind speed, particles transported during snowfall have a lower settling velocity than particles transported without snowfall. This difference confirms earlier observations (Takahashi, 1985) and can be explained by the change of drag coefficient between dendritic and rounded particles. This difference pertains several hours after the end of the snowfall illustrating the fragmentation of snow grains during blowing snow events.

  14. Characterization of a Quadrotor Unmanned Aircraft System for Aerosol-Particle-Concentration Measurements.

    Science.gov (United States)

    Brady, James M; Stokes, M Dale; Bonnardel, Jim; Bertram, Timothy H

    2016-02-01

    High-spatial-resolution, near-surface vertical profiling of atmospheric chemical composition is currently limited by the availability of experimental platforms that can sample in constrained environments. As a result, measurements of near-surface gradients in trace gas and aerosol particle concentrations have been limited to studies conducted from fixed location towers or tethered balloons. Here, we explore the utility of a quadrotor unmanned aircraft system (UAS) as a sampling platform to measure vertical and horizontal concentration gradients of trace gases and aerosol particles at high spatial resolution (1 m) within the mixed layer (0-100 m). A 3D Robotics Iris+ autonomous quadrotor UAS was outfitted with a sensor package consisting of a two-channel aerosol optical particle counter and a CO2 sensor. The UAS demonstrated high precision in both vertical (±0.5 m) and horizontal positions (±1 m), highlighting the potential utility of quadrotor UAS drones for aerosol- and trace-gas measurements within complex terrain, such as the urban environment, forest canopies, and above difficult-to-access areas such as breaking surf. Vertical profiles of aerosol particle number concentrations, acquired from flights conducted along the California coastline, were used to constrain sea-spray aerosol-emission rates from coastal wave breaking. PMID:26730457

  15. A comparison of methods used to calculate normal background concentrations of potentially toxic elements for urban soil

    Energy Technology Data Exchange (ETDEWEB)

    Rothwell, Katherine A., E-mail: k.rothwell@ncl.ac.uk; Cooke, Martin P., E-mail: martin.cooke@ncl.ac.uk

    2015-11-01

    To meet the requirements of regulation and to provide realistic remedial targets there is a need for the background concentration of potentially toxic elements (PTEs) in soils to be considered when assessing contaminated land. In England, normal background concentrations (NBCs) have been published for several priority contaminants for a number of spatial domains however updated regulatory guidance places the responsibility on Local Authorities to set NBCs for their jurisdiction. Due to the unique geochemical nature of urban areas, Local Authorities need to define NBC values specific to their area, which the national data is unable to provide. This study aims to calculate NBC levels for Gateshead, an urban Metropolitan Borough in the North East of England, using freely available data. The ‘median + 2MAD’, boxplot upper whisker and English NBC (according to the method adopted by the British Geological Survey) methods were compared for test PTEs lead, arsenic and cadmium. Due to the lack of systematically collected data for Gateshead in the national soil chemistry database, the use of site investigation (SI) data collected during the planning process was investigated. 12,087 SI soil chemistry data points were incorporated into a database and 27 comparison samples were taken from undisturbed locations across Gateshead. The SI data gave high resolution coverage of the area and Mann–Whitney tests confirmed statistical similarity for the undisturbed comparison samples and the SI data. SI data was successfully used to calculate NBCs for Gateshead and the median + 2MAD method was selected as most appropriate by the Local Authority according to the precautionary principle as it consistently provided the most conservative NBC values. The use of this data set provides a freely available, high resolution source of data that can be used for a range of environmental applications. - Highlights: • The use of site investigation data is proposed for land contamination studies

  16. Monitoring of black carbon and size-segregated particle number concentrations at 9-m and 65-m distances from a major road in Helsinki

    Energy Technology Data Exchange (ETDEWEB)

    Pakkanen, T.A.; Maekelae, T.; Hillamo, R.E. [Finnish Meteorological Inst., Helsinki (Finland); Virtanen, A.; Roenkkoe, T.; Keskinen, J. [Tampere Univ. of Technology, Inst. of Physics, Aerosol Physics Lab. , Tampere (Finland); Pirjola, L.; Parviainen, H. [Helsinki Polytechnic, Dept. of Technology, Helsinki (Finland); Hussein, T.; Haemeri, K. [Helsinki Univ., Dept. of Physical Sciences, Helsinki (Finland)

    2006-07-01

    In February and August 2003, black carbon (BC) and size-segregated particle number concentrations were monitored simultaneously at 9-m and 65-m distances from a major road in Helsinki, Finland, using aethalometers and electrical low-pressure impactors, respectively. During weekdays in winter, the average total particle number concentrations in the diameter range 0.007-1{mu}m increased during morning rush hours from the nighttime values of 17000 and 12000 cm{sup -3} to 190000 and 130000 cm{sup -3} at the 9-m and 65-m stations, respectively. The corresponding BC concentrations increased from 730 and 430 ng m{sup -3} to 2800 and 1550 ng m{sup -3}. Compared with those in winter, the average rush-hour particle number concentrations were much lower in summer, the likely reason being enhanced nucleation in cold winter conditions. BC concentrations were slightly higher during summer than during winter. Number size distributions measured at the 9-m and 65-m distances and at a background site had similar modal characteristics with the highest peak occurring below 0.03 {mu}m. Despite the different wind conditions in winter and summer, concentrations of total particle number and BC decreased similarly between the 9-m and 65-m stations, the likely principal mechanism being mixing with background air. The strong diurnal variation in concentrations during the weekdays, together with the large concentration difference between the 9-m and 65-m distances, suggests that local traffic was the main source of the measured pollutants, especially during rush hours at the 9-m site. In winter, the decrease in the particle number concentrations from the 9-m site to the 65-m site was most pronounced for the smallest exhaust particles. During an episodic pollution event in winter there were indications of condensational growth of 0.007-0.03 {mu}m particles, which increased the number concentration of 0.03-0.06 {mu}m particles at the 65-m site. (orig.)

  17. Thermodynamic correction of particle concentrations measured by underwing probes on fast flying aircraft

    Science.gov (United States)

    Weigel, R.; Spichtinger, P.; Mahnke, C.; Klingebiel, M.; Afchine, A.; Petzold, A.; Krämer, M.; Costa, A.; Molleker, S.; Jurkat, T.; Minikin, A.; Borrmann, S.

    2015-12-01

    Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function of flight velocity. In particular for fast-flying aircraft the necessity arises to account for compression of the air sample volume. Hence, a correction procedure is needed to invert measured particle number concentrations to ambient conditions that is commonly applicable for different instruments to gain comparable results. In the compression region where the detection of particles occurs (i.e. under factual measurement conditions), pressure and temperature of the air sample are increased compared to ambient (undisturbed) conditions in certain distance away from the aircraft. Conventional procedures for scaling the measured number densities to ambient conditions presume that the particle penetration speed through the instruments' detection area equals the aircraft speed (True Air Speed, TAS). However, particle imaging instruments equipped with pitot-tubes measuring the Probe Air Speed (PAS) of each underwing probe reveal PAS values systematically below those of the TAS. We conclude that the deviation between PAS and TAS is mainly caused by the compression of the probed air sample. From measurements during two missions in 2014 with the German Gulfstream G-550 (HALO - High Altitude LOng range) research aircraft we develop a procedure to correct the measured particle concentration to ambient conditions using a thermodynamic approach. With the provided equation the corresponding concentration correction factor ξ is applicable to the high frequency measurements of each underwing probe which is equipped with its own air speed sensor (e.g. a pitot-tube). ξ-values of 1 to 0.85 are calculated for air speeds (i.e. TAS) between 60 and 260 m s-1. From HALO data it is found that ξ does not significantly vary between the different deployed instruments. Thus, for the current HALO underwing probe configuration a parameterisation of

  18. On the potential contribution of open lead particle emissions to the central Arctic aerosol concentration

    Directory of Open Access Journals (Sweden)

    A. Held

    2010-10-01

    Full Text Available During the ice-breaker borne ASCOS expedition (Arctic Summer Cloud Ocean Study direct eddy covariance measurements of aerosol number fluxes were carried out in August 2008 on the edge of an ice floe drifting in the central Arctic Ocean between 2°–10° W longitude and 87°–87.5° N latitude. The median aerosol transfer velocities over different surface types (open water leads, ice ridges, snow and ice surfaces ranged from 0.27 to 0.68 mm s−1 during deposition-dominated episodes. Emission periods were observed more frequently over the open lead, while the snow behaved primarily as a deposition surface. Directly measured aerosol fluxes were compared with particle deposition parameterizations in order to estimate the emission flux from the observed net aerosol flux. Finally, the contribution of the open lead particle source to atmospheric variations in particle number concentration was evaluated and compared with the observed temporal evolution of particle number. The direct emission of aerosol particles from the open lead can only explain 5–10% of the observed particle number variation in the mixing layer close to the surface.

  19. Particle concentration measurement of virus samples using electrospray differential mobility analysis and quantitative amino acid analysis.

    Science.gov (United States)

    Cole, Kenneth D; Pease, Leonard F; Tsai, De-Hao; Singh, Tania; Lute, Scott; Brorson, Kurt A; Wang, Lili

    2009-07-24

    Virus reference materials are needed to develop and calibrate detection devices and instruments. We used electrospray differential mobility analysis (ES-DMA) and quantitative amino acid analysis (AAA) to determine the particle concentration of three small model viruses (bacteriophages MS2, PP7, and phiX174). The biological activity, purity, and aggregation of the virus samples were measured using plaque assays, denaturing gel electrophoresis, and size-exclusion chromatography. ES-DMA was developed to count the virus particles using gold nanoparticles as internal standards. ES-DMA additionally provides quantitative measurement of the size and extent of aggregation in the virus samples. Quantitative AAA was also used to determine the mass of the viral proteins in the pure virus samples. The samples were hydrolyzed and the masses of the well-recovered amino acids were used to calculate the equivalent concentration of viral particles in the samples. The concentration of the virus samples determined by ES-DMA was in good agreement with the concentration predicted by AAA for these purified samples. The advantages and limitations of ES-DMA and AAA to characterize virus reference materials are discussed.

  20. Indoor and outdoor concentrations of fine particles, particle-bound PAHs and volatile organic compounds in Kaunas, Lithuania.

    Science.gov (United States)

    Kliucininkas, Linas; Martuzevicius, Dainius; Krugly, Edvinas; Prasauskas, Tadas; Kauneliene, Violeta; Molnar, Peter; Strandberg, Bo

    2011-01-01

    This complex study presents indoor and outdoor levels of air-borne fine particles, particle-bound PAHs and VOCs at two urban locations in the city of Kaunas, Lithuania, and considers possible sources of pollution. Two sampling campaigns were performed in January-February and March-April 2009. The mean outdoor PM(2.5) concentration at Location 1 in winter was 34.5 ± 15.2 µg m(-3) while in spring it was 24.7 ± 12.2 µg m(-3); at Location 2 the corresponding values were 36.7 ± 21.7 and 22.4 ± 19.4 µg m(-3), respectively. In general there was little difference between the PM concentrations at Locations 1 and 2. PM(2.5) concentrations were lower during the spring sampling campaign. These PM concentrations were similar to those in many other European cities; however, the levels of most PAHs analysed were notably higher. The mean sum PAH concentrations at Locations 1 and 2 in the winter campaign were 75.1 ± 32.7 and 32.7 ± 11.8 ng m(-3), respectively. These differences are greater than expected from the difference in traffic intensity at the two sites, suggesting that there is another significant source of PAH emissions at Location 1 in addition to the traffic. The low observed indoor/outdoor (I/O) ratios indicate that PAH emissions at the locations studied arise primarily from outdoor sources. The buildings at both locations have old windows with wooden frames that are fairly permissive in terms of air circulation. VOC concentrations were mostly low and comparable to those reported from Sweden. The mean outdoor concentrations of VOC's were: 0.7 ± 0.2, 3.0 ± 0.8, 0.5 ± 0.2, 3.5 ± 0.3, and 0.2 ± 0.1 µg m(-3), for benzene, toluene, ethylbenzene, sum of m-, p-, o-xylenes, and naphthalene, respectively. Higher concentrations of VOCs were observed during the winter campaign, possibly due to slower dispersion, slower chemical transformations and/or the lengthy "cold start" period required by vehicles in the wintertime. A trajectory analysis showed that air masses

  1. Evaluation and modelling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki ─ Part I: Modelling results within the LIPIKA project

    Directory of Open Access Journals (Sweden)

    M. Ketzel

    2007-08-01

    Full Text Available A field measurement campaign was conducted near a major road "Itäväylä" in an urban area in Helsinki in 17–20 February 2003. Aerosol measurements were conducted using a mobile laboratory "Sniffer" at various distances from the road, and at an urban background location. Measurements included particle size distribution in the size range of 7 nm–10 μm (aerodynamic diameter by the Electrical Low Pressure Impactor (ELPI and in the size range of 3–50 nm (mobility diameter by Scanning Mobility Particle Sizer (SMPS, total number concentration of particles larger than 3 nm detected by an ultrafine condensation particle counter (UCPC, temperature, relative humidity, wind speed and direction, driving route of the mobile laboratory, and traffic density on the studied road. In this study, we have compared measured concentration data with the predictions of the road network dispersion model CAR-FMI used in combination with an aerosol process model MONO32. For model comparison purposes, one of the cases was additionally computed using the aerosol process model UHMA, combined with the CAR-FMI model. The vehicular exhaust emissions, and atmospheric dispersion and transformation of fine and ultrafine particles was evaluated within the distance scale of 200 m (corresponding to a time scale of a couple of minutes. We computed the temporal evolution of the number concentrations, size distributions and chemical compositions of various particle size classes. The atmospheric dilution rate of particles is obtained from the roadside dispersion model CAR-FMI. Considering the evolution of total number concentration, dilution was shown to be the most important process. The influence of coagulation and condensation on the number concentrations of particle size modes was found to be negligible on this distance scale. Condensation was found to affect the evolution of particle diameter in the two smallest particle modes. The assumed value of the concentration of

  2. Motion and orientation of cylindrical and cubic particles in pipe flow with high concentration and high particle to pipe size ratio

    Institute of Scientific and Technical Information of China (English)

    Xiao-ke KU; Jian-zhong LIN

    2008-01-01

    Lattice Boltzmann method was used to numerically investigate the motion and orientation distribution of cylindrical and cubic particles in pipe flow with high concentration and high particle to pipe size ratio. The transient impulse model of 3D collisions between particles and between particle and wall is proposed. The numerical results are qualitatively in agreement with and quantitatively comparable to the experiment data. The results show that the increases of both the cylindrical particle to pipe size ratio and the particle aspect ratio decrease the rotation about all axes. All rotations of cubic particles decrease with increasing the particle concentration. The cubic particles, rotating more drastically in the flow with large Reynolds number, rotate faster than the cylindrical particles with the same size. The cylindrical particles align with the flow direction more obviously with decreasing Reynolds numbers. However, the orientations of cubic particles are spread all over the range with no significant difference in magnitude, and the Reynolds numbers have no obvious effect on the orientations of cubic particles.

  3. Evaluation of the performance of a particle concentrator for on-line instrumentation

    Directory of Open Access Journals (Sweden)

    S. Saarikoski

    2014-03-01

    Full Text Available The performance of the miniature Versatile Aerosol Concentration Enrichment System (m-VACES, Geller et al., 2005 was investigated in laboratory and field studies using on-line instruments. Laboratory tests focused on the behavior of monodisperse ammonium sulfate (AS or dioctyl sebacate (DOS particles in the m-VACES measured with the Aerodynamic Particle Sizer (APS and Scanning Mobility Particle Sizer (SMPS. The ambient measurements were conducted at an urban site in Helsinki, Finland, where the operation of the m-VACES was explored in conjunction with a Soot Particle Aerosol Mass Spectrometer (SP-AMS in addition to the SMPS. In laboratory tests, the growth of particles in water vapor produced a stable droplet size distribution independent of the original particle size. However, when the droplets were dried with the goal of measuring the original size distribution, a shift to larger particles was observed for small particle sizes (up to ~ 200 nm in mobility diameter. That growth was probably caused by water-soluble organic compounds absorbed on the water droplets from the gas phase, but not evaporated in the drying phase. In ambient measurements, similar enrichment factors (EFs were observed for nitrate, sulfate, organics and refractory black carbon. Size-dependent EFs showed a small shift in the accumulation mode peak size after the m-VACES. The presence of acidic ambient particles affected the enrichment of ammonium and chloride. Gaseous ammonia was observed to be absorbed on acidic particles in the m-VACES, neutralizing the aerosol. As a result the contribution of ammonium to particle mass increased from 6% for ambient to 9% for concentrated aerosol. The opposite trend was observed for chloride, since a fraction of chloride evaporated from acidic particles upon neutralization. Organic artifacts were quite small but a small positive artifact for hydrocarbons and nitrogen-containing organic compounds was observed. However, the oxidation state of

  4. Submicron particle mass concentrations and sources in the Amazonian wet season (AMAZE-08)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Q.; Farmer, D. K.; Rizzo, L. V.; Pauliqueivis, T.; Kuwata, Mikinori; Karl, Thomas G.; Guenther, Alex B.; Allan, James D.; Coe, H.; Andreae, M. O.; Poeschl, U.; Jiminez, J. L.; Artaxo, Paulo; Martin, Scot T.

    2015-01-01

    Real-time mass spectra of non-refractory component of submicron aerosol particles were recorded in a tropical rainforest in the central Amazon basin during the wet season of 2008, as a part of the Amazonian Aerosol Characterization Experiment (AMAZE-08). Organic components accounted on average for more than 80% of the non-refractory submicron particle mass concentrations during the period of measurements. Ammonium was present in sufficient quantities to halfway neutralize sulfate. In this acidic, isoprene-dominated, low-NOx environment the high-resolution mass spectra as well as mass closures with ion chromatography measurements did not provide evidence for significant contributions of organosulfate species, at least at concentrations above uncertainty levels. Positive-matrix factorization of the time series of particle mass spectra identified four statistical factors to account for the variance of the signal intensities of the organic constituents: a factor HOA having a hydrocarbon-like signature and identified as regional emissions of primary organic material, a factor OOA-1 associated with fresh production of secondary organic material by a mechanism of BVOC oxidation followed by gas-to-particle conversion, a factor OOA-2 consistent with reactive uptake of isoprene oxidation products, especially epoxydiols by acidic particles, and a factor OOA-3 associated with long range transport and atmospheric aging. The OOA-1, -2, and -3 factors had progressively more oxidized signatures. Diameter-resolved mass spectral markers also suggested enhanced reactive uptake of isoprene oxidation products to the accumulation mode for the OOA-2 factor, and such size partitioning can be indicative of in-cloud process. The campaign-average factor loadings were in a ratio of 1.1:1.0 for the OOA-1 compared to the OOA-2 pathway, suggesting the comparable importance of gas-phase compared to particle-phase (including cloud waters) production pathways of secondary organic material during

  5. Particle size distribution and PAH concentrations of incense smoke in a combustion chamber

    Energy Technology Data Exchange (ETDEWEB)

    Yang, C.-R. [Department of Environmental Engineering National Cheng Kung University, 1, University Road, Tainan 70101, Taiwan (China); Sustainable Environment Research Center, National Cheng Kung University, 1, University Road, Tainan 70101, Taiwan (China); Lin, T.-C. [Department of Environmental Engineering National Cheng Kung University, 1, University Road, Tainan 70101, Taiwan (China) and Sustainable Environment Research Center, National Cheng Kung University, 1, University Road, Tainan 70101, Taiwan (China)]. E-mail: tachang@mail.ncku.edu.tw; Chang, F.-H. [Department of Information Management, Tzu Hui Institute of Technology, 367 SanMing Road, Pingtung, 926 Taiwan (China)

    2007-01-15

    The particle size distribution and the concentrations of polycyclic aromatic hydrocarbons (PAHs) in incense smoke were studied using a custom-designed combustion chamber. Among the nine types of incense investigated, the particle and the total PAH emission factors varied significantly. The average mass median aerodynamic diameter (MMAD) of the smoke aerosol was 262 {+-} 49 nm, which positively correlated to particle emission factor (mg/stick, p < 0.05). Coagulation was a major mechanism that dictates the MMAD of the smoke. The total toxic equivalency (the sum of the benzo[a]pyrene equivalent concentration) of the solid-phase PAHs (S-PAHs) was over 40 times higher than that of the corresponding gas-phase PAHs, indicating that the S-PAHs in incense smoke may pose potential health risk. Experiments show that each lowered percentage of total carbon content in the raw incense helped decrease the particle emission factor by 2.6 mg/g-incense, and the reduction of S-PAH emission factor ranged from 8.7 to 26% when the carbon content was lowered from 45 to 40%. - Emission profiles of PAHs from the nine types of studied incense appeared to share a common pattern.

  6. Reynolds number influence on preferential concentration of heavy particles in turbulent flows

    Energy Technology Data Exchange (ETDEWEB)

    Obligado, Martin; Missaoui, Mahrane; Cartellier, Alain; Bourgoin, Mickaeel [Laboratoire des Ecoulements Geophysiques et Industriels, CNRS/UJF/G-INP UMR5519, BP53, 38041 Grenoble cedex 9 (France); Monchaux, Romain, E-mail: mickael.bourgoin@hmg.inpg.fr [Unite de mecanique, Ecole Nationale Superieure de Techniques Avancees, ParisTech, Chemin de la Huniere, 91761, Palaiseau Cedex (France)

    2011-12-22

    We present a study of the preferential concentration and clustering in homogeneous and isotropic turbulence. Using Voronoie diagrams, we have formerly quantified preferential concentration as a function of the Stokes number in moderate turbulence conditions up to Reynolds number based on Taylor microscale of the order of R{sub {lambda}} {approx} 120. Using an active grid recently implemented in our windtunnel, we investigate in the present study, the effect of Reynolds number on particles clustering, in the range R{sub {lambda}} {approx} 200 - 400.

  7. Development of a methodology for the quantification of particle number and gaseous concentrations in a bidirectional bus tunnel and the derivation of emission factors

    Science.gov (United States)

    Lechowicz, Stan; Jayaratne, Rohan; Morawska, Lidia; Jamriska, Milan

    Particle number, NO x and CO concentrations were measured simultaneously at the air entry portal and at the mid-point of a 511 m bidirectional road tunnel, used entirely by urban public transport buses. The aim of this study was to provide information on concentrations of these pollutants inside a unique bus tunnel, and to develop a viable methodology for determining emission factors for on-road vehicles. Measurements were made continuously over a period of five days that included a complete weekend. Traffic flow rate and air flow rate were also monitored. The mean particle number concentration at mid-tunnel was 4.1 × 10 4 cm -3, which was over four times higher than the urban background concentration. The mean concentrations of NO x and CO at mid-tunnel were 464 ppb and 802 ppb, respectively. All these values were between 2 and 4 times higher than at the air entry portal. Median concentrations during selected time segments coinciding with the morning and evening rush hours, mid-day during weekdays and full day during the weekends were determined and the corresponding bus emission factors of each of the three parameters was calculated. Mean emission factors found for particle number, NO x and CO were 7.1 × 10 14 particles km -1, 8.1 g km -1 and 15.9 g km -1, respectively. These values compared well with previous studies, showing that the methodology adopted was sound and viable.

  8. Detection limits for ferrimagnetic particle concentrations using magnetic resonance imaging based proton transverse relaxation rate measurements

    Energy Technology Data Exchange (ETDEWEB)

    Pardoe, H [School of Physics, University of Western Australia, Crawley, Perth, WA 6009 (Australia); Chua-anusorn, W [School of Physics, University of Western Australia, Crawley, Perth, WA 6009 (Australia); Pierre, T G St [School of Physics, University of Western Australia, Crawley, Perth, WA 6009 (Australia); Dobson, J [Department of Biomedical Engineering and Medical Physics, Centre for Science and Technology in Medicine, Keele University, Thornburrow Drive, Hartshill, Stoke-on-Trent, ST4 7QB (United Kingdom)

    2003-03-21

    A clinical magnetic resonance imaging (MRI) system was used to measure proton transverse relaxation rates (R{sub 2}) in agar gels with varying concentrations of ferrimagnetic iron oxide nanoparticles in a field strength of 1.5 T. The nanoparticles were prepared by coprecipitation of ferric and ferrous ions in the presence of either dextran or polyvinyl alcohol. The method of preparation resulted in loosely packed clusters (dextran) or branched chains (polyvinyl alcohol) of particles containing of the order of 600 and 400 particles, respectively. For both methods of particle preparation, concentrations of ferrimagnetic iron in agar gel less than 0.01 mg ml{sup -1} had no measurable effect on the value of R{sub 2} for the gel. The results indicate that MRI-based R{sub 2} measurements using 1.5 T clinical scanners are not quite sensitive enough to detect the very low concentrations of nanoparticulate biogenic magnetite reported in human brain tissue. (note)

  9. Concentrations, size distributions and temporal variations of fluorescent biological aerosol particles in southern tropical India

    Science.gov (United States)

    Valsan, Aswathy; Krishna R, Ravi; CV, Biju; Huffman, Alex; Poschl, Ulrich; Gunthe, Sachin

    2015-04-01

    Biological aerosols constitute a wide range of dead and alive biological materials and structures that are suspended in the atmosphere. They play an important role in the atmospheric physical, chemical and biological processes and health of living being by spread of diseases among humans, plants, and, animals. The atmospheric abundance, sources, physical properties of PBAPs as compared to non-biological aerosols, however, is poorly characterized. The Indian tropical region, where large fraction of the world's total population is residing, experiences a distinctive meteorological phenomenon by means of Indian Summer Monsoon (IMS). Thus, the properties and characteristics of biological aerosols are also expected to be very diverse over the Indian subcontinent depending upon the seasons. Here we characterize the number concentration and size distribution of Fluorescent Biological Aerosol Particles (FBAP) at a high altitude continental site, Munnar (10.09 N, 77.06 E; 1605 m asl) in South India during the South-West monsoon, which constitute around 80 percent of the annual rainfall in Munnar. Continuous three months measurements (from 01 June 2014 to 21 Aug 2104) FBAPs were carried out at Munnar using Ultra Violet Aerodynamic Particle Sizer (UVAPS) during IMS. The mean number and mass concentration of coarse FBAP averaged over the entire campaign was 1.7 x 10-2 cm-3 and 0.24 µg m-3 respectively, which corresponds to 2 percent and 6 percent of total aerosol particle number and mass concentration. In agreement to other previous measurements the number size distribution of FBAP also peaks at 3.2 micron indicating the strong presence of fungal spores. This was also supported by the Scanning Electron Microscopic analysis of bioaerosols on filter paper. They also displayed a strong diurnal cycle with maximum concentration occurring at early morning hours. During periods of heavy and continuous rain where the wind is consistently blowing from South-West direction it was

  10. Fine particles (PM2.5) at a CAWNET background site in Central China: Chemical compositions, seasonal variations and regional pollution events

    Science.gov (United States)

    Zhang, Fan; Cheng, Hai-rong; Wang, Zu-wu; Lv, Xiao-pu; Zhu, Zhong-min; Zhang, Gan; Wang, Xin-ming

    2014-04-01

    Fine particle (PM2.5) samples were collected at Jinsha (JSH), a regional background China Atmosphere Watch Network (CAWNET) site in Central China from March 2012 to March 2013. The mass concentrations of water-soluble inorganic ions (WSIIs), organic carbon (OC) and elemental carbon (EC) in PM2.5 were measured. The average PM2.5 mass concentration was 48.7 ± 26.9 μg m-3, exceeding the Chinese National Ambient Air Quality Standards (NAAQS) (35 μg m-3), implying that PM2.5 is a pollutant of regional concern in Central China. The average concentrations of total WSIIs, OC and EC were 26.1 ± 18.8, 7.5 ± 3.5 and 0.7 ± 0.5 μg m-3, accounting for 53.5%, 15.1% and 1.5% of the PM2.5 concentrations at JSH, respectively. Clear seasonal variations in PM2.5 and the levels of its main chemical species were observed in the following order: winter > autumn > spring > summer. Backward air trajectory analysis and potential source contribution function (PSCF) analysis implied that the areas north and northeast of JSH contributed significantly to the levels of SO42-, NO3-, NH4+ and OC, while sandstorms originating from Mongolia and traveling across Northwest China may have contributed significantly to the levels of Na+, Ca2+, and Mg2+ in PM2.5 at JSH. Two pollution events, related to regional biomass burning and haze, respectively, were recorded at JSH during the sampling campaign.

  11. Modeling effects of abrasive particle size and concentration on material removal at molecular scale in chemical mechanical polishing

    International Nuclear Information System (INIS)

    A novel material removal model as a function of abrasive particle size and concentration was established in chemical mechanical polishing (CMP) based on molecular scale mechanism, micro-contact mechanics and probability statistics. A close-form equation was firstly developed to calculate the number of effective particles. It found nonlinear dependences of removal rate on the particle size and concentration, being qualitatively agreement with the published experimental data. The nonlinear relation results from the couple relationship among abrasive number, slurry concentration and surface atoms' binding energy with the particle size. Finally, the system parameters such as the operational conditions and materials properties were incorporated into the model as well.

  12. Cox's particle in magnetic and electric fields against the background of euclidean and spherical geometries

    International Nuclear Information System (INIS)

    The generalized relativistic Klein-Fock-Gordon equation for Cox's non-point scalar particle with intrinsic structure is solved in the presence of external uniform magnetic and electric fields in the Minkowski space. Similar problems in the non-relativistic approximation in a closed spherical Riemann 3-space are examined. The complete separation of the variables in the system of special cylindric coordinates in a curved model is performed. In the presence of a magnetic field, the quantum problem in the radial variable is solved exactly, and the wave functions and the corresponding energy levels are found: the quantum motion in the z-direction is described by a one-dimensional Schrodinger-like equation in an effective potential, which turns out to be too di?cult for the analytical treatment. In the presence of an electric field against the background of the curved model, the situation is similar: the radial equation is solved exactly in hypergeometric functions, but the equation in the z-variable can be examined only qualitatively

  13. Comparison of sources of submicron particle number concentrations measured at two sites in Rochester, NY

    International Nuclear Information System (INIS)

    Sources contributing to the submicron particles (100-470 nm) measured between January 2002 and December 2007 at two different New York State Department of Environmental Conservation (NYS DEC) sites in Rochester, NY were identified and apportioned using a bilinear receptor model, positive matrix factorization (PMF). Measurements of aerosol size distributions and number concentrations for particles in the size range of 10-500 nm have been made since December 2001 to date in Rochester. The measurements are being made using a scanning mobility particle sizer (SMPS) consisting of a DMA and a CPC (TSI models 3071 and 3010, respectively). From December 2001 to March 2004, particle measurements were made at the NYS DEC site in downtown Rochester, but it was moved to the eastside of Rochester in May 2004. Each measurement period was divided into three seasons i.e., winter (December, January, and February), summer (June, July, and August), and the transitional periods (March, April, May, September, October, and November) so as to avoid experimental uncertainty resulting from too large season-to-season variability in ambient temperature and solar photon intensity that would lead to unstable/non-stationary size distributions. Therefore, the seasons were analyzed independently for possible sources. Ten sources were identified at both sites and these include traffic, nucleation, residential/commercial heating, industrial emissions, secondary nitrate, ozone- rich secondary aerosol, secondary sulfate, regionally transported aerosol, and a mixed source of nucleation and traffic. These results show that the measured total outdoor particle number concentrations in Rochester generally vary with similar temporal patterns, suggesting that the central monitoring site data can be used to estimate outdoor exposure in other parts of the city.

  14. Multi-step process for concentrating magnetic particles in waste sludges

    Science.gov (United States)

    Watson, John L.

    1990-01-01

    This invention involves a multi-step, multi-force process for dewatering sludges which have high concentrations of magnetic particles, such as waste sludges generated during steelmaking. This series of processing steps involves (1) mixing a chemical flocculating agent with the sludge; (2) allowing the particles to aggregate under non-turbulent conditions; (3) subjecting the mixture to a magnetic field which will pull the magnetic aggregates in a selected direction, causing them to form a compacted sludge; (4) preferably, decanting the clarified liquid from the compacted sludge; and (5) using filtration to convert the compacted sludge into a cake having a very high solids content. Steps 2 and 3 should be performed simultaneously. This reduces the treatment time and increases the extent of flocculation and the effectiveness of the process. As partially formed aggregates with active flocculating groups are pulled through the mixture by the magnetic field, they will contact other particles and form larger aggregates. This process can increase the solids concentration of steelmaking sludges in an efficient and economic manner, thereby accomplishing either of two goals: (a) it can convert hazardous wastes into economic resources for recycling as furnace feed material, or (b) it can dramatically reduce the volume of waste material which must be disposed.

  15. Understanding how roadside concentrations of NOx are influenced by the background levels, traffic density, and meteorological conditions using Boosted Regression Trees

    Science.gov (United States)

    Sayegh, Arwa; Tate, James E.; Ropkins, Karl

    2016-02-01

    Oxides of Nitrogen (NOx) is a major component of photochemical smog and its constituents are considered principal traffic-related pollutants affecting human health. This study investigates the influence of background concentrations of NOx, traffic density, and prevailing meteorological conditions on roadside concentrations of NOx at UK urban, open motorway, and motorway tunnel sites using the statistical approach Boosted Regression Trees (BRT). BRT models have been fitted using hourly concentration, traffic, and meteorological data for each site. The models predict, rank, and visualise the relationship between model variables and roadside NOx concentrations. A strong relationship between roadside NOx and monitored local background concentrations is demonstrated. Relationships between roadside NOx and other model variables have been shown to be strongly influenced by the quality and resolution of background concentrations of NOx, i.e. if it were based on monitored data or modelled prediction. The paper proposes a direct method of using site-specific fundamental diagrams for splitting traffic data into four traffic states: free-flow, busy-flow, congested, and severely congested. Using BRT models, the density of traffic (vehicles per kilometre) was observed to have a proportional influence on the concentrations of roadside NOx, with different fitted regression line slopes for the different traffic states. When other influences are conditioned out, the relationship between roadside concentrations and ambient air temperature suggests NOx concentrations reach a minimum at around 22 °C with high concentrations at low ambient air temperatures which could be associated to restricted atmospheric dispersion and/or to changes in road traffic exhaust emission characteristics at low ambient air temperatures. This paper uses BRT models to study how different critical factors, and their relative importance, influence the variation of roadside NOx concentrations. The paper

  16. Primary standard for the number concentration of liquid-borne particles in the 10 to 20 µm diameter range

    International Nuclear Information System (INIS)

    The national primary standard for the number concentration of liquid-borne particles in the 10 to 20 µm diameter range has been developed at the National Institute of Advanced Industrial Science and Technology (AIST), Japan. The standard consists of a total number counting type flow cytometer (T-FCM) and an electronic balance. The T-FCM is a commercial flow cytometer modified so that the total number of particles in an aqueous suspension sampled in a test tube can be counted, and the electronic balance is used to determine the mass of the suspension. This standard is intended to be used for calibrating commercial standard suspensions of monodisperse polystyrene latex (PSL) particles. The measurand in the calibration is the mass-based number concentration (the particle number in a unit mass of a suspension), and the calibration capability covers the concentration range from 5 × 102 to 2 × 106 particles g−1. When the concentration of the suspension is higher than 2 × 103 particles g−1, the suspension is first diluted to about 1 × 103 particles g−1 to suppress the coincidence loss in particle counting by the T-FCM. The validity of the calibration with the T-FCM was examined by comparison with an independent method in which a scanning electron microscope (SEM) was used to determine the number concentration of particles deposited on a silicon wafer. For a suspension of 10 µm PSL particles with a concentration of approximately 1 × 106 particles g−1, the concentration values determined by the T-FCM and SEM methods were 1.042 × 106 and 1.035 × 106 particles g−1, respectively: The difference was less than 0.7%. The relative expanded uncertainty of the measurement by the T-FCM method with the coverage factor k = 2 was 4.4%

  17. Observations of the aerosol particle number concentration in the marine boundary layer over the south-eastern Baltic Sea

    Directory of Open Access Journals (Sweden)

    Dalia Jasinevičiene

    2013-08-01

    Full Text Available Continuous measurements of the aerosol particle number concentration (PNCin the size range from 4.5 nm to 2 µm were performed at the Preila marine background site during 2008–2009.The concentration maxima in summer was twice the average (2650±50 cm-3. A trajectory-based approach was applied for source identification. Potential Source Contribution Function (PSCFanalysis was performed to estimate the possible contribution of long-range andlocal PNC transport to PNC concentrations recorded at the marine backgroundsite. The PSCF results showed that the marine boundary layer was not seriouslyaffected by long-range transport, but that local transport of air pollutionwas recognized as an important factor. North Atlantic and Sea-Marine typeclusters respectively represented 32.1% and 17.9% of the total PNC spectraand were characterized by the lowest PNCs (1080±1340 and 1210±1040 cm-3 respectively among all clusters.   Wavelet transformation analysis of 1-h aerosol PNC indicated that whilethe 16-h scale was a constant feature of aerosol PNC evolution in spring, the longer (∼60-h scalesappeared mainly over the whole year (except June. Principal componentanalysis (PCA revealed a strong correlation between PNC and NaCl,highlighting the influence of sea-salt aerosols. In addition, PCA also showedthat PNC depended on optical and meteorological parameters such as UVR andtemperature.

  18. Analysis of the Hydrogen Reduction Rate of Magnetite Concentrate Particles in a Drop Tube Reactor Through CFD Modeling

    Science.gov (United States)

    Fan, Deqiu; Mohassab, Yousef; Elzohiery, Mohamed; Sohn, H. Y.

    2016-06-01

    A computational fluid dynamics (CFD) approach, coupled with experimental results, was developed to accurately evaluate the kinetic parameters of iron oxide particle reduction. Hydrogen reduction of magnetite concentrate particles was used as a sample case. A detailed evaluation of the particle residence time and temperature profile inside the reactor is presented. This approach eliminates the errors associated with assumptions like constant particle temperature and velocity while the particles travel down a drop tube reactor. The gas phase was treated as a continuum in the Eulerian frame of reference, and the particles are tracked using a Lagrangian approach in which the trajectory and velocity are determined by integrating the equation of particle motion. In addition, a heat balance on the particle that relates the particle temperature to convection and radiation was also applied. An iterative algorithm that numerically solves the governing coupled ordinary differential equations was developed to determine the pre-exponential factor and activation energy that best fit the experimental data.

  19. Ventilation dependence of concentration metrics of Ultra-fine Particles in a coagulating household smoke.

    Science.gov (United States)

    Anand, S; Sreekanth, B; Mayya, Y S

    2016-01-01

    Role of Ultra-fine Particles (UFPs) in causing adverse health effects among large population across the world, attributable to household smoke, is being increasingly recognized. However, there is very little theoretical perspective available on the complex behavior of the UFP metrics with respect to controlling factors, such as ventilation rate and particle emission rate from the combustion sources. This numerical study examines through coagulation dynamics, the dependence of UFP metrics, viz., number (PN), mass (PM(0.1)) and surface area (PA(0.1)) concentrations below 0.1 μm diameter, on ventilation and the number emission rate from household smoke. For strong sources, the steady-state concentrations of these metrics are found to increase initially with increasing Air Exchange Rate (AER), reach a peak value and then decrease. Counter correlations are seen between UFP metric and PM(2.5) concentrations. The concepts of Critical Air Exchange Rate (CAER) and Half-Value Air Exchange Rate (HaVAER) have been introduced which indicate a feasibility of mitigation of PM(0.1) and PA(0.1), unlike PN, by ventilation techniques. The study clearly brings forth complex differential behavior of the three UFP metrics. The results are further discussed. PMID:26795205

  20. Background dust emission following grassland fire: a snapshot across the particle-size spectrum highlights how high-resolution measurements enhance detection

    Energy Technology Data Exchange (ETDEWEB)

    Whicker, Jeffrey J [Los Alamos National Laboratory; Martin, Luis M [UNIV OF ARIZONA; Field, Jason P [UNIV OF ARIZONA; Villegas, Juan C [UNIV OF ARIZONA; Brehsears, David D [UNIV OF ARIZONA; Law, Darin J [UNIV OF ARIZONA; Urgeghe, Anna M [UNIV OF ARIZONA

    2009-01-01

    Dust emission rates vary temporally and with particle size. Many studies of dust emission focus on a particular temporal scale and the portion of the particle-size spectrum associated with a single instrument; fewer studies have assessed dust emission across the particle-size spectrum and associated temporal scales using multiple instruments. Particularly lacking are measurements following disturbances such as fire that are high-resolution and focused on finer particles - those with direct implications for human health and potential for long-distance biogeochemical transport - during less windy but more commonly occurring background conditions. We measured dust emissions in unburned and burned semiarid grassland using four different instruments spanning different combinations of temporal resolution and particle-size spectrum: Big Springs Number Eight (BSNE) and Sensit instruments for larger saltating particles, DustTrak instruments for smaller suspended particles, and Total Suspended Particulate (TSP) samplers for measuring the entire range of particle sizes. Unburned and burned sites differed in vegetation cover and aerodynamic roughness, yet surprisingly differences in dust emission rates were only detectable for saltation using BSNE and for smaller aerosols using DustTrak. Our results, surprising in the lack of consistently detected differences, indicate that high-resolution DustTrak measurements offered the greatest promise for detecting differences in background emission rates and that BSNE samplers, which integrate across height, were effective for longer intervals. More generally, our results suggest that interplay between particle size, temporal resolution, and integration across time and height can be complex and may need to be considered more explicitly for effective sampling for background dust emissions.

  1. Field evaluation of a new particle concentrator- electrostatic precipitator system for measuring chemical and toxicological properties of particulate matter

    Directory of Open Access Journals (Sweden)

    Pakbin Payam

    2008-11-01

    Full Text Available Abstract Background A newly designed electrostatic precipitator (ESP in tandem with Versatile Aerosol Concentration Enrichment System (VACES was developed by the University of Southern California to collect ambient aerosols on substrates appropriate for chemical and toxicological analysis. The laboratory evaluation of this sampler is described in a previous paper. The main objective of this study was to evaluate the performance of the new VACES-ESP system in the field by comparing the chemical characteristics of the PM collected in the ESP to those of reference samplers operating in parallel. Results The field campaign was carried out in the period from August, 2007 to March, 2008 in a typical urban environment near downtown Los Angeles. Each sampling set was restricted to 2–3 hours to minimize possible sampling artifacts in the ESP. The results showed that particle penetration increases and ozone concentration decreases with increasing sampling flow rate, with highest particle penetration observed between 100 nm and 300 nm. A reference filter sampler was deployed in parallel to the ESP to collect concentration-enriched aerosols, and a MOUDI sampler was used to collect ambient aerosols. Chemical analysis results showed very good agreement between the ESP and MOUDI samplers in the concentrations of trace elements and inorganic ions. The overall organic compound content of PM collected by the ESP, including polycyclic aromatic hydrocarbons (PAHs, hopanes, steranes, and alkanes, was in good agreement with that of the reference sampler, with an average ESP -to -reference concentration ratio of 1.07 (± 0.38. While majority of organic compound ratios were close to 1, some of the semi-volatile organic species had slightly deviated ratios from 1, indicating the possibility of some sampling artifacts in the ESP due to reactions of PM with ozone and radicals generated from corona discharge, although positive and negative sampling artifacts in the

  2. Ultrasonic device for real-time sewage velocity and suspended particles concentration measurements.

    Science.gov (United States)

    Abda, F; Azbaid, A; Ensminger, D; Fischer, S; François, P; Schmitt, P; Pallarès, A

    2009-01-01

    In the frame of a technological research and innovation network in water and environment technologies (RITEAU, Réseau de Recherche et d'Innovation Technologique Eau et Environnement), our research group, in collaboration with industrial partners and other research institutions, has been in charge of the development of a suitable flowmeter: an ultrasonic device measuring simultaneously the water flow and the concentration of size classes of suspended particles. Working on the pulsed ultrasound principle, our multi-frequency device (1 to 14 MHz) allows flow velocity and water height measurement and estimation of suspended solids concentration. Velocity measurements rely on the coherent Doppler principle. A self developed frequency estimator, so called Spectral Identification method, was used and compared to the classical Pulse-Pair method. Several measurements campaigns on one wastewater collector of the French city of Strasbourg gave very satisfactory results and showed smaller standard deviation values for the Doppler frequency extracted by the Spectral Identification method. A specific algorithm was also developed for the water height measurements. It relies on the water surface acoustic impedance rupture and its peak localisation and behaviour in the collected backscattering data. This algorithm was positively tested on long time measurements on the same wastewater collector. A large part of the article is devoted to the measurements of the suspended solids concentrations. Our data analysis consists in the adaptation of the well described acoustic behaviour of sand to the behaviour of wastewater particles. Both acoustic attenuation and acoustic backscattering data over multiple frequencies are analyzed for the extrapolation of size classes and respective concentrations. Under dry weather conditions, the massic backscattering coefficient and the overall size distribution showed similar evolution whatever the measurement site was and were suggesting a global

  3. Variations in retention efficiency of bivalves to different concentrations and organic content of suspended particles

    Institute of Scientific and Technical Information of China (English)

    张继红; 方建光; 梁兴明

    2010-01-01

    Retention efficiencies (RE) of scallop (Chlamys farreri),oyster (Crassostrea gigas) and mussel (Mytilus edulis) in a flow-through system were measured to understand the short-term response to various particle and organic matter concentrations.By comparing the RE of C.farreri with that of C.gigas and M.edulis,we gained further knowledge on the feeding physiological characteristics of C.farreri and ascertained the possible cause of high summer mortalities of this species.The experimental feeding conditions in...

  4. Reduction of indoor particles concentration using re-circulating filtration units in Danish dwellings

    DEFF Research Database (Denmark)

    Spilak, Michal; Frederiksen, Marie; Karottki, Gabriela D.;

    2012-01-01

    . This exposure can be reduced by using re-circulating filtration units, limiting the impact of outdoor pollution penetration, indoor emissions and decomposition of dust on heated surfaces. The objective of this study was to investigate whether reducing the indoor particulate concentration, by means of specially...... designed re-circulating particle filtration unit, will have positive impact on cardiovascular and respiratory health among elderly people. Two units were placed in each of 27 apartments situated in the Greater Copenhagen area, close to highly trafficked roads. In both, filtered and placebo periods, indoor...

  5. On the peculiarities of LDA method in two-phase flows with high concentrations of particles

    Science.gov (United States)

    Poplavski, S. V.; Boiko, V. M.; Nesterov, A. U.

    2016-10-01

    Popular applications of laser Doppler anemometry (LDA) in gas dynamics are reviewed. It is shown that the most popular method cannot be used in supersonic flows and two-phase flows with high concentrations of particles. A new approach to implementation of the known LDA method based on direct spectral analysis, which offers better prospects for such problems, is presented. It is demonstrated that the method is suitable for gas-liquid jets. Owing to the progress in laser engineering, digital recording of spectra, and computer processing of data, the method is implemented at a higher technical level and provides new prospects of diagnostics of high-velocity dense two-phase flows.

  6. Ultrasonic device for real-time sewage velocity and suspended particles concentration measurements.

    Science.gov (United States)

    Abda, F; Azbaid, A; Ensminger, D; Fischer, S; François, P; Schmitt, P; Pallarès, A

    2009-01-01

    In the frame of a technological research and innovation network in water and environment technologies (RITEAU, Réseau de Recherche et d'Innovation Technologique Eau et Environnement), our research group, in collaboration with industrial partners and other research institutions, has been in charge of the development of a suitable flowmeter: an ultrasonic device measuring simultaneously the water flow and the concentration of size classes of suspended particles. Working on the pulsed ultrasound principle, our multi-frequency device (1 to 14 MHz) allows flow velocity and water height measurement and estimation of suspended solids concentration. Velocity measurements rely on the coherent Doppler principle. A self developed frequency estimator, so called Spectral Identification method, was used and compared to the classical Pulse-Pair method. Several measurements campaigns on one wastewater collector of the French city of Strasbourg gave very satisfactory results and showed smaller standard deviation values for the Doppler frequency extracted by the Spectral Identification method. A specific algorithm was also developed for the water height measurements. It relies on the water surface acoustic impedance rupture and its peak localisation and behaviour in the collected backscattering data. This algorithm was positively tested on long time measurements on the same wastewater collector. A large part of the article is devoted to the measurements of the suspended solids concentrations. Our data analysis consists in the adaptation of the well described acoustic behaviour of sand to the behaviour of wastewater particles. Both acoustic attenuation and acoustic backscattering data over multiple frequencies are analyzed for the extrapolation of size classes and respective concentrations. Under dry weather conditions, the massic backscattering coefficient and the overall size distribution showed similar evolution whatever the measurement site was and were suggesting a global

  7. The role of dust storms in total atmospheric particle concentrations at two sites in the western U.S.

    Science.gov (United States)

    Neff, Jason C.; Reynolds, Richard L.; Munson, Seth M.; Fernandez, Daniel; Belnap, Jayne

    2013-01-01

    Mineral aerosols are produced during the erosion of soils by wind and are a common source of particles (dust) in arid and semiarid regions. The size of these particles varies widely from less than 2 µm to larger particles that can exceed 50 µm in diameter. In this study, we present two continuous records of total suspended particle (TSP) concentrations at sites in Mesa Verde and Canyonlands National Parks in Colorado and Utah, USA, respectively, and compare those values to measurements of fine and coarse particle concentrations made from nearby samplers. Average annual concentrations of TSP at Mesa Verde were 90 µg m−3 in 2011 and at Canyonlands were 171 µg m−3 in 2009, 113 µg m−3 in 2010, and 134 µg m−3 in 2011. In comparison, annual concentrations of fine (diameter of 2.5 µm and below) and coarse (2.5–10 µm diameter) particles at these sites were below 10 µg m−3 in all years. The high concentrations of TSP appear to be the result of regional dust storms with elevated concentrations of particles greater than 10 µm in diameter. These conditions regularly occur from spring through fall with 2 week mean TSP periodically in excess of 200 µg m−3. Measurement of particles on filters indicates that the median particle size varies between approximately 10 µm in winter and 40 µm during the spring. These persistently elevated concentrations of large particles indicate that regional dust emission as dust storms and events are important determinants of air quality in this region.

  8. Evaluation of background concentrations of selected chemical and radiochemical constituents in water from the eastern Snake River Plain aquifer at and near the Idaho National Laboratory, Idaho

    Science.gov (United States)

    Bartholomay, Roy C.; L. Flint Hall,

    2016-05-05

    The U.S. Geological Survey and Idaho Department of Environmental Quality Idaho National Laboratory (INL) Oversight Program in cooperation with the U.S. Department of Energy determined background concentrations of selected chemical and radiochemical constituents in the eastern Snake River Plain aquifer to aid with ongoing cleanup efforts at the INL. Chemical and radiochemical constituents including calcium, magnesium, sodium, potassium, silica, chloride, sulfate, fluoride, bicarbonate, chromium, nitrate, tritium, strontium-90, chlorine-36, iodine-129, plutonium-238, plutonium-239, -240 (undivided), americium-241, technetium-99, uranium-234, uranium-235, and uranium-238 were selected for the background study because they were either not analyzed in earlier studies or new data became available to give a more recent determination of background concentrations. Samples of water collected from wells and springs at and near the INL that were not believed to be influenced by wastewater disposal were used to identify background concentrations. Groundwater in the eastern Snake River Plain aquifer at and near the INL was divided into two major water types (western tributary and eastern regional) based on concentrations of lithium less than and greater than 5 micrograms per liter (μg/L). Median concentrations for each constituent were used to define the upper limit of background.

  9. Determination of kinetic effects on particle size and concentration: instruction for scale up

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Ling; Nakamura, Hiroyuki; Lee Changi; Uehara, Masato; Maeda, Hideaki, E-mail: maeda-h@aist.go.jp [Measurement solution Research Center, Micro-Space Chemistry Solution Team, AIST, 807-1, Shuku, Tosu, Saga (Japan)

    2011-10-29

    Increasing the synthesis scale is one of the most important issues in nanocrystal synthesis. The main difference between small and large reactor is their thermal transfer rate which is reported to have great effects on particle nucleation and growth. In this paper, CdSe Quantum dots synthesis as was used as a model to investigate the heating rate effects in a microreactor system capable of precisely controlling the temperature and heating rate. Results showed that heating rate effects highly depended on the synthesis parameters. For example, in 5% Dodecanamine (DDA) case, there was no heating rate effect; while in the case of 20% DDA case, heating rate could affect both particle size distribution and morphology. Test experiments to demonstrate the up-scalability have been conducted and the results showed that products synthesized by batch reactor were comparable with microreactor products: Batch reactor gave same product when the DDA concentration was 5% but quite different product when the DDA concentration was 20%, compared with microreactor products. The data on the effects of heating rate obtained by this set up have high reliability and enable us to choose the proper method to increase the synthesis scale.

  10. Aviation Emissions Impact Ambient Ultrafine Particle Concentrations in the Greater Boston Area.

    Science.gov (United States)

    Hudda, N; Simon, M C; Zamore, W; Brugge, D; Durant, J L

    2016-08-16

    Ultrafine particles are emitted at high rates by jet aircraft. To determine the possible impacts of aviation activities on ambient ultrafine particle number concentrations (PNCs), we analyzed PNCs measured from 3 months to 3.67 years at three sites within 7.3 km of Logan International Airport (Boston, MA). At sites 4.0 and 7.3 km from the airport, average PNCs were 2- and 1.33-fold higher, respectively, when winds were from the direction of the airport compared to other directions, indicating that aviation impacts on PNC extend many kilometers downwind of Logan airport. Furthermore, PNCs were positively correlated with flight activity after taking meteorology, time of day and week, and traffic volume into account. Also, when winds were from the direction of the airport, PNCs increased with increasing wind speed, suggesting that buoyant aircraft exhaust plumes were the likely source. Concentrations of other pollutants [CO, black carbon (BC), NO, NO2, NOx, SO2, and fine particulate matter (PM2.5)] decreased with increasing wind speed when winds were from the direction of the airport, indicating a different dominant source (likely roadway traffic emissions). Except for oxides of nitrogen, other pollutants were not correlated with flight activity. Our findings point to the need for PNC exposure assessment studies to take aircraft emissions into consideration, particularly in populated areas near airports. PMID:27490267

  11. Ultrasonic Method for Concentration and Particle Size Analysis in Dense Coal-water Slurry

    Science.gov (United States)

    Xue, Minghua; Su, Mingxu; Dong, Lili; Shang, Zhitao; Cai, Xiaoshu

    2007-06-01

    The concentration and particle size distribution in particulate two-phase flow are the important parameters in a wide variety of industrial areas. For the purpose of on-line characterizing dense coal-water slurry, ultrasonic methods have many advantages, such as no-dilution, real-time and no-invasion, while light-based techniques are not capable of providing information because optical methods normally require the sample to be diluted. In this paper, the modified Urick equation including temperature modification, which can be used to determine concentration from the measurement of velocity in the coal-water slurry, is evaluated on the basis of model analysis and experiments. Combined with the optimum regulation technique inverse algorithm, the particle size distribution of the coal-water slurry is obtained according to the attenuation prediction of Coupled-phase model plus Bouguer-Lambert-Beer-Law scattering model and experimental attenuation at frequencies ranges from 3MHz to 12MHz. This technique brings the possibility of using ultrasound for on-line measurement of dense slurry.

  12. Determination of kinetic effects on particle size and concentration: instruction for scale up

    Science.gov (United States)

    Zhang, Ling; Nakamura, Hiroyuki; Lee, Changi; Uehara, Masato; Maeda, Hideaki

    2011-10-01

    Increasing the synthesis scale is one of the most important issues in nanocrystal synthesis. The main difference between small and large reactor is their thermal transfer rate which is reported to have great effects on particle nucleation and growth. In this paper, CdSe Quantum dots synthesis as was used as a model to investigate the heating rate effects in a microreactor system capable of precisely controlling the temperature and heating rate. Results showed that heating rate effects highly depended on the synthesis parameters. For example, in 5% Dodecanamine (DDA) case, there was no heating rate effect; while in the case of 20% DDA case, heating rate could affect both particle size distribution and morphology. Test experiments to demonstrate the up-scalability have been conducted and the results showed that products synthesized by batch reactor were comparable with microreactor products: Batch reactor gave same product when the DDA concentration was 5% but quite different product when the DDA concentration was 20%, compared with microreactor products. The data on the effects of heating rate obtained by this set up have high reliability and enable us to choose the proper method to increase the synthesis scale.

  13. Characterization and source apportionment of particle number concentration at a semi-urban tropical environment.

    Science.gov (United States)

    Khan, Md Firoz; Latif, Mohd Talib; Amil, Norhaniza; Juneng, Liew; Mohamad, Noorlin; Nadzir, Mohd Shahrul Mohd; Hoque, Hossain Mohammed Syedul

    2015-09-01

    Principal component analysis (PCA) and correlation have been used to study the variability of particle mass and particle number concentrations (PNC) in a tropical semi-urban environment. PNC and mass concentration (diameter in the range of 0.25->32.0 μm) have been measured from 1 February to 26 February 2013 using an in situ Grimm aerosol sampler. We found that the 24-h average total suspended particulates (TSP), particulate matter ≤10 μm (PM10), particulate matter ≤2.5 μm (PM2.5) and particulate matter ≤1 μm (PM1) were 14.37 ± 4.43, 14.11 ± 4.39, 12.53 ± 4.13 and 10.53 ± 3.98 μg m(-3), respectively. PNC in the accumulation mode (spectroradiometer (MODIS) distribution. PMID:25925145

  14. Constraints on the annihilation cross section of dark matter particles from anisotropies in the diffuse gamma-ray background measured with Fermi-LAT

    NARCIS (Netherlands)

    S. Ando; E. Komatsu

    2013-01-01

    Annihilation of dark matter particles in cosmological halos (including the halo of the Milky Way) contributes to the diffuse gamma-ray background (DGRB). As this contribution will appear anisotropic in the sky, one can use the angular power spectrum of anisotropies in the DGRB to constrain the prope

  15. Giant In-Particle Field Concentration and Fano Resonances at Light Scattering by High-Refractive Index Particles

    OpenAIRE

    Tribelsky, M. I.; Miroshnichenko, A. E.

    2015-01-01

    A detailed analytical inspection of light scattering by a particle with high refractive index m+i\\kappa and small dissipative constant \\kappa is presented. We have shown that there is a dramatic difference in the behavior of the electromagnetic field within the particle (inner problem) and the scattered field outside it (outer problem). With an increase in m at fix values of the other parameters, the field within the particle asymptotically converges to a periodic function of m. The electric ...

  16. Force acting on a dielectric particle in a concentration gradient by ionic concentration polarization under an externally applied DC electric field.

    Science.gov (United States)

    Kang, Kwan Hyoung; Li, Dongqing

    2005-06-15

    There is a concentration-polarization (CP) force acting on a particle submerged in an electrolyte solution with a concentration (conductivity) gradient under an externally applied DC electric field. This force originates from the two mechanisms: (i) gradient of electrohydrodynamic pressure around the particle developed by the Coulombic force acting on induced free charges by the concentration polarization, and (ii) dielectric force due to nonuniform electric field induced by the conductivity gradient. A perturbation analysis is performed for the electric field, the concentration field, and the hydrodynamic field, under the assumptions of creeping flow and small concentration gradient. The leading order component of this force acting on a dielectric spherical particle is obtained by integrating the Maxwell and the hydrodynamic stress tensors. The analytical results are validated by comparing the surface pressure and the skin friction to those of a numerical analysis. The CP force is proportional to square of the applied electric field, effective for electrically neutral particles, and always directs towards the region of higher ionic concentration. The magnitude of the CP force is compared to that of the electrophoretic and the conventional dielectrophoretic forces. PMID:15897097

  17. Immersion freezing in concentrated solution droplets for a variety of ice nucleating particles

    Science.gov (United States)

    Wex, Heike; Kohn, Monika; Grawe, Sarah; Hartmann, Susan; Hellner, Lisa; Herenz, Paul; Welti, Andre; Lohmann, Ulrike; Kanji, Zamin; Stratmann, Frank

    2016-04-01

    The measurement campaign LINC (Leipzig Ice Nucleation counter Comparison) was conducted in September 2015, during which ice nucleation measurements as obtained with the following instruments were compared: - LACIS (Leipzig Aerosol Cloud Interaction Simulator, see e.g. Wex et al., 2014) - PIMCA-PINC (Portable Immersion Mode Cooling Chamber together with PINC) - PINC (Portable Ice Nucleation Chamber, Chou et al., 2011) - SPIN (SPectrometer for Ice Nuclei, Droplet Measurement Technologies) While LACIS and PIMCA-PINC measured immersion freezing, PINC and SPIN varied the super-saturation during the measurements and collected data also for relative humidities below 100% RHw. A suite of different types of ice nucleating particles were examined, where particles were generated from suspensions, subsequently dried and size selected. For the following samples, data for all four instruments are available: K-feldspar, K-feldspar treated with nitric acid, Fluka-kaolinite and birch pollen. Immersion freezing measurements by LACIS and PIMCA-PINC were in excellent agreement. Respective parameterizations from these measurement were used to model the ice nucleation behavior below water vapor saturation, assuming that the process can be described as immersion freezing in concentrated solutions. This is equivalent to simply including a concentration dependent freezing point depression in the immersion freezing parameterization, as introduced for coated kaolinite particles in Wex et al. (2014). Overall, measurements performed below water vapor saturation were reproduced by the model, and it will be discussed in detail, why deviations were observed in some cases. Acknowledgement: Part of this work was funded by the DFG Research Unit FOR 1525 INUIT, grant WE 4722/1-2. Literature: Chou, C., O. Stetzer, E. Weingartner, Z. Juranyi, Z. A. Kanji, and U. Lohmann (2011), Ice nuclei properties within a Saharan dust event at the Jungfraujoch in the Swiss Alps, Atmos. Chem. Phys., 11(10), 4725

  18. Occurrence and Concentrations of Halogenated Flame Retardants in the Atmospheric Fine Particles in Chinese Cities.

    Science.gov (United States)

    Liu, Di; Lin, Tian; Shen, Kaijun; Li, Jun; Yu, Zhiqiang; Zhang, Gan

    2016-09-20

    The concentrations of halogenated flame retardants (HFRs) in PM2.5 were monitored for one year at 10 urban sites in China during 2013-2014. This study investigated four classes of HFRs: nine polybrominated diphenyl ethers (PBDEs), six nonbromodiphenyl ether (BDE) brominated flame retardants, two dechlorane plus (DP) flame retardants, and three chlorinated organophosphate flame retardants (OPFRs). Extremely high concentrations of BDE-209 and DBDPE were observed in only one city (Guangzhou), which was a consequence of the intensive e-waste recycling and disposal operations in the Pearl River Delta. This result differed from the tris(monochloropropyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP) distributions, which showed high concentrations in most cities, suggesting wide usage and large emissions in China in recent years. The highest TCPP and TCEP concentrations were observed in the summer, indicating that emission from local sources was an important factor controlling the levels in the air. This was not the case for BDE-209 and DBDPE, for which higher concentrations were found in winter. When bound to particulate matter due to low vapor pressure, these compounds may be more persistent in air, and temperature-dependent gas-particle partitioning was a key factor. Moreover, regional pollution and long-range transport had a significant influence on the seasonal distributions of BDE-209 and DBDPE, especially in cities (Guangzhou and Shanghai) close to electrical/electronic waste recycling sites. Residents in urban areas were exposed to higher levels of chlorinated OPFRs. This raises considerable concern, and an appropriate risk assessment is required. PMID:27539248

  19. Beyond phthalates: Gas phase concentrations and modeled gas/particle distribution of modern plasticizers

    Energy Technology Data Exchange (ETDEWEB)

    Schossler, Patricia [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Institute of Environmental and Sustainable Chemistry, Technische Universitaet Braunschweig, Hagenring 30, D-38106 Braunschweig (Germany); Schripp, Tobias, E-mail: tobias.schripp@wki.fraunhofer.de [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Salthammer, Tunga [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Bahadir, Muefit [Institute of Environmental and Sustainable Chemistry, Technische Universitaet Braunschweig, Hagenring 30, D-38106 Braunschweig (Germany)

    2011-09-01

    The ongoing health debate about polymer plasticizers based on the esters of phthalic acid, especially di(2-ethylhexyl) phthalate (DEHP), has caused a trend towards using phthalates of lower volatility such as diisononyl phthalate (DINP) and towards other acid esters, such as adipates, terephthalates, citrates, etc. Probably the most important of these so-called 'alternative' plasticizers is diisononyl cyclohexane-1,2-dicarboxylate (DINCH). In the indoor environment, the continuously growing market share of this compound since its launch in 2002 is inter alia apparent from the increasing concentration of DINCH in settled house dust. From the epidemiological point of view there is considerable interest in identifying how semi-volatile organic compounds (SVOCs) distribute in the indoor environment, especially in air, airborne particles and sedimented house dust. This, however, requires reliable experimental concentration data for the different media and good measurements or estimates of their physical and chemical properties. This paper reports on air concentrations for DINP, DINCH, diisobutyl phthalate (DIBP), diisobutyl adipate (DIBA), diisobutyl succinate (DIBS) and diisobutyl glutarate (DIBG) from emission studies in the Field and Laboratory Emission Cell (FLEC). For DINP and DINCH it took about 50 days to reach the steady-state value: for four months no decay in the concentration could be observed. Moreover, vapor pressures p{sub 0} and octanol-air partitioning coefficients K{sub OA} were obtained for 37 phthalate and non-phthalate plasticizers from two different algorithms: EPI Suite and SPARC. It is shown that calculated gas/particle partition coefficients K{sub p} and fractions can widely differ due to the uncertainty in the predicted p{sub 0} and K{sub OA} values. For most of the investigated compounds reliable experimental vapor pressures are not available. Rough estimates can be obtained from the measured emission rate of the pure compound in a

  20. A particle velocity sensor to measure the sound from a structure in the presence of background noise

    NARCIS (Netherlands)

    Bree, de H.E.; Druyvesteyn, W.F.

    2005-01-01

    The performance (or quality) of a product is often checked by measuring the radiated sound (noise) from the vibrating structure. Often this test has to be done in an environment with background noise, which makes the measurement difficult. When using a (pressure) microphone the background noise can

  1. A Stochastic Framework For Sediment Concentration Estimation By Accounting Random Arrival Processes Of Incoming Particles Into Receiving Waters

    Science.gov (United States)

    Tsai, C.; Hung, R. J.

    2015-12-01

    This study attempts to apply queueing theory to develop a stochastic framework that could account for the random-sized batch arrivals of incoming sediment particles into receiving waters. Sediment particles, control volume, mechanics of sediment transport (such as mechanics of suspension, deposition and resuspension) are treated as the customers, service facility and the server respectively in queueing theory. In the framework, the stochastic diffusion particle tracking model (SD-PTM) and resuspension of particles are included to simulate the random transport trajectories of suspended particles. The most distinguished characteristic of queueing theory is that customers come to the service facility in a random manner. In analogy to sediment transport, this characteristic is adopted to model the random-sized batch arrival process of sediment particles including the random occurrences and random magnitude of incoming sediment particles. The random occurrences of arrivals are simulated by Poisson process while the number of sediment particles in each arrival can be simulated by a binominal distribution. Simulations of random arrivals and random magnitude are proposed individually to compare with the random-sized batch arrival simulations. Simulation results are a probabilistic description for discrete sediment transport through ensemble statistics (i.e. ensemble means and ensemble variances) of sediment concentrations and transport rates. Results reveal the different mechanisms of incoming particles will result in differences in the ensemble variances of concentrations and transport rates under the same mean incoming rate of sediment particles.

  2. Concentrated ambient ultrafine particle exposure induces cardiac change in young healthy volunteers

    Science.gov (United States)

    Exposure to ambient ultrafine particles has been associated with cardiopulmonary toxicity and mortality. Adverse effects specifically linked to ultrafine particles include loss of sympathovagal balance and altered hemostasis. To characterize the effects of ultrafine particles in ...

  3. The effects of vehicle emissions and nucleation events on vertical particle concentration profiles around urban office buildings

    Directory of Open Access Journals (Sweden)

    T. N. Quang

    2012-01-01

    Full Text Available Despite its role in determining both indoor and outdoor human exposure to anthropogenic particles, there is limited information describing vertical profiles of particle concentrations in urban environments, especially for ultrafine particles. Furthermore, the results of the few studies performed have been inconsistent. As such this study aimed to assess the influence of vehicle emissions and nucleation formation on particle concentrations (PN and PM2.5 at different heights around three urban office buildings located next to busy roads in Brisbane, Australia, and place these results in the broader context of the existing literature. Two sets of instruments were used to simultaneously measure PN size distribution, PN and PM2.5 concentrations, respectively, for up to three weeks each at three office buildings.

    The results showed that both PN and PM2.5 concentrations around building envelope were influenced by vehicle emissions and new particle formation, and that they exhibited variability across the three different office buildings. During the nucleation event, PN concentrations increased (21–46%, while PM2.5 concentrations decreased (36–52% with height at all three buildings.

    This study has shown an underappreciated role of nucleation in producing particles that can affect large numbers of people, due to the high density and occupancy of urban office buildings and the fact that the vast majority of people's time is spent indoors. These findings highlight important new information related to the previously overlooked role of particle formation in the urban atmosphere and its potential effects on selection of air intake locations and appropriate filter types when designing or upgrading mechanical ventilation systems in urban office buildings. The results also serve to better define particle behaviour and variability around building envelopes, which has implications for studies of

  4. Seasonal variation of atmospheric particle number concentrations, new particle formation and atmospheric oxidation capacity at the high Arctic site Villum Research Station, Station Nord

    Science.gov (United States)

    Nguyen, Quynh T.; Glasius, Marianne; Sørensen, Lise L.; Jensen, Bjarne; Skov, Henrik; Birmili, Wolfram; Wiedensohler, Alfred; Kristensson, Adam; Nøjgaard, Jacob K.; Massling, Andreas

    2016-09-01

    This work presents an analysis of the physical properties of sub-micrometer aerosol particles measured at the high Arctic site Villum Research Station, Station Nord (VRS), northeast Greenland, between July 2010 and February 2013. The study focuses on particle number concentrations, particle number size distributions and the occurrence of new particle formation (NPF) events and their seasonality in the high Arctic, where observations and characterization of such aerosol particle properties and corresponding events are rare and understanding of related processes is lacking.A clear accumulation mode was observed during the darker months from October until mid-May, which became considerably more pronounced during the prominent Arctic haze months from March to mid-May. In contrast, nucleation- and Aitken-mode particles were predominantly observed during the summer months. Analysis of wind direction and wind speed indicated possible contributions of marine sources from the easterly side of the station to the observed summertime particle number concentrations, while southwesterly to westerly winds dominated during the darker months. NPF events lasting from hours to days were mostly observed from June until August, with fewer events observed during the months with less sunlight, i.e., March, April, September and October. The results tend to indicate that ozone (O3) might be weakly anti-correlated with particle number concentrations of the nucleation-mode range (10-30 nm) in almost half of the NPF events, while no positive correlation was observed. Calculations of air mass back trajectories using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for the NPF event days suggested that the onset or interruption of events could possibly be explained by changes in air mass origin. A map of event occurrence probability was computed, indicating that southerly air masses from over the Greenland Sea were more likely linked to those events.

  5. Adsorption of zinc on manganite (γ-MnOOH):particle concentration effect and adsorption reversibility

    Institute of Scientific and Technical Information of China (English)

    QIN Yan-wen; PAN Gang; ZHANG Ming-ming; LI Xian-liang

    2004-01-01

    The adsorption and desorption processes of Zn(Ⅱ) on γ-MnOOH as a function of particle concentrations (Cp) were studied. An obvious Cp effect was observed in this adsorption system. The degree of adsorption hysteresis increased greatly with the increasing of Cp, indicating that the extent of the real metastable-equilibrium states deviating from the ideal equilibrium state was enhanced with the increasing of Cp. The Cp-reversibility relationship confirmed the metastable-equilibrium adsorption (MEA) inequality (Pan, 1998a), which was the core formulation of the MEA theory. Because the MEA inequality was based on the basic hypothesis of MEA theory that adsorption density Г is not a state variable, the Cp-reversibility relationship gave indirect evidence to the basic hypothesis of MEA theory.

  6. Concentration and particle size of airborne toxic algae (brevetoxin) derived from ocean red tide events.

    Science.gov (United States)

    Cheng, Yung Sung; McDonald, Jacob D; Kracko, Dean; Irvin, C Mitch; Zhou, Yue; Pierce, Richard H; Henry, Michael S; Bourdelaisa, Andrea; Naar, Jerome; Baden, Daniel G

    2005-05-15

    Red tides in the Gulf of Mexico are formed by blooms of the dinoflagellate Karenia brevis, which produces brevetoxins (PbTx). Brevetoxins can be transferred from water to air in the wind-powered whitecapped waves during red tide episodes. Inhalation exposure to marine aerosol containing PbTx causes respiratory problems. A liquid chromatograph/ tandem mass spectrometric method was developed for the detection and quantitation of several PbTxs in ambient samples collected during red tide events. This method was complemented by a previously developed antibody assay that analyzes the entire class of PbTx compounds. The method showed good linearity, accuracy, and reproducibility, allowing quantitation of PbTx compounds in the 10 pg/m3 range. Air concentrations of PbTxs and brevenal for individual samples ranged from 0.01 to 80 ng/m3. The particle size showed a single mode with a mass median diameter between 6 and 10 microm, which was consistent for all of the PbTx species that were measured. Our results imply that individual PbTxs were from the same marine aerosol or from marine aerosol that was produced from the same process. The particle size indicated the likelihood of high deposition efficiency in the respiratory tract with the majority of aerosol deposited in the upper airways and small but not insignificant deposition in the lower airways. PMID:15954221

  7. Impurity identifications, concentrations and particle fluxes from spectral measurements of the EXTRAP T2R plasma

    Science.gov (United States)

    Menmuir, S.; Kuldkepp, M.; Rachlew, E.

    2006-10-01

    An absolute intensity calibrated 0.5 m spectrometer with optical multi-channel analyser detector was used to observe the visible-UV radiation from the plasma in the EXTRAP T2R reversed field pinch experiment. Spectral lines were identified indicating the presence of oxygen, chromium, iron and molybdenum impurities in the hydrogen plasma. Certain regions of interest were examined in more detail and at different times in the plasma discharge. Impurity concentration calculations were made using the absolute intensities of lines of OIV and OV measured at 1-2 ms into the discharge generating estimates of the order of 0.2% of ne in the central region rising to 0.7% of ne at greater radii for OIV and 0.3% rising to 0.6% for OV. Edge electron temperatures of 0.5-5 eV at electron densities of 5-10×1011 cm-3 were calculated from the measured relative intensities of hydrogen Balmer lines. The absolute intensities of hydrogen lines and of multiplets of neutral chromium and molybdenum were used to determine particle fluxes (at 4-5 ms into the plasma) of the order 1×1016, 7×1013 and 3×1013 particles cm-2 s-1, respectively.

  8. Correlations between urban atmospheric light extinction coefficients and fine particle mass concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Trier, A.; Cabrini, N.; Ferrer, J. [Facultad de Ciencia, Universidad de Santiago de Chile, Santiago 2 (Chile); Olaeta, I. [SESMA, Santiago 1 (Chile)

    1997-07-01

    Total horizontal atmospheric light extinction coefficients as well as particle mass concentrations have been measured in downtown areas of Santiago de Chile, a heavily polluted city. Measurement campaigns were carried out in 1994 in 1995. Extinction measurements were made by a telephotometric technique in four wavelength bands; oscillating mass balance type instruments were used to measure PM2.5 and PM10 mass concentrations. The latter type instrument had not been available heretofore. The extensive continuous PM2.5 measurements are the first for this city. Strong and highly significant statistical correlations were found between extinction coefficients and mass concentrations, especially with the fine respirable or PM2.5 mass concentrations. Angstrom exponents and, in one case, mass extinction coefficients have been estimated. [Spanish] Se ha medido coeficientes atmosfericos totales horizontales de extincion de luz asi como concentraciones de masa de particulas atmosfericas en zonas centricas de Santiago de Chile, una ciudad altamente contaminada. Las campanas de medicion se han hecho en 1994 y en 1995. Las mediciones de extincion se han hecho por un metodo telefotometrico en cuatro bandas espectrales; las concentraciones de masa PM2.5 y PM10 se han medido con instrumentos del tipo de balanzas de masa oscilantes. Tales instrumentos no han estado disponibles durante trabajos anteriores. Las extensas mediciones continuas de concentraciones de masa PM2.5 son las primeras para Santiago de Chile. Se han encontrado fuertes correlaciones estadisticas, altamente significativas, entre coeficientes de extincion y concentraciones de masa, especialmente las concentraciones de particulas finas respirables PM2.5. Se han estimado tambien exponentes de Angstrom y, en un caso, coeficientes masicos de extincion.

  9. Concentrations and fluxes of aerosol particles during the LAPBIAT measurement campaign in Värriö field station

    Directory of Open Access Journals (Sweden)

    T. M. Ruuskanen

    2007-01-01

    Full Text Available The LAPBIAT measurement campaign took place in the SMEAR I measurement station located in Eastern Lapland in the spring of 2003 between 26 April and 11 May. In this paper we describe the measurement campaign, concentrations and fluxes of aerosol particles, air ions and trace gases, paying special attention to an aerosol particle formation event broken by a polluted air mass approaching from industrial areas of Kola Peninsula, Russia. Aerosol particle number flux measurements show strong downward fluxes during that time. Concentrations of coarse aerosol particles were high for 1–2 days before the nucleation event (i.e. 28–29 April, very low immediately before and during the observed aerosol particle formation event (30 April and increased moderately from the moment of sudden break of the event. In general particle deposition measurements based on snow samples show the same changes. Measurements of the mobility distribution of air ions showed elevated concentrations of intermediate air ions during the particle formation event. We estimated the growth rates in the nucleation mode size range. For particles <10 nm, the growth rate increases with size on 30 April. Dispersion modelling made with model SILAM support the conclusion that the nucleation event was interrupted by an outbreak of sulphate-rich air mass in the evening of 30 April that originated from the industry at Kola Peninsula, Russia. The results of this campaign highlight the need for detailed research in atmospheric transport of air constituents for understanding the aerosol dynamics.

  10. Measurement of Event Background Fluctuations for Charged Particle Jet Reconstruction in Pb-Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV

    CERN Document Server

    Abelev, Betty; Adamova, Dagmar; Adare, Andrew Marshall; Aggarwal, Madan; Aglieri Rinella, Gianluca; Agocs, Andras Gabor; Agostinelli, Andrea; Aguilar Salazar, Saul; Ahammed, Zubayer; Ahmad, Arshad; Ahmad, Nazeer; Ahn, Sang Un; Akindinov, Alexander; Aleksandrov, Dmitry; Alessandro, Bruno; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Almaraz Avina, Erick Jonathan; Alt, Torsten; Altini, Valerio; Altinpinar, Sedat; Altsybeev, Igor; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anson, Christopher Daniel; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshauser, Harald; Arbor, Nicolas; Arcelli, Silvia; Arend, Andreas; Armesto, Nestor; Arnaldi, Roberta; Aronsson, Tomas Robert; Arsene, Ionut Cristian; Arslandok, Mesut; Asryan, Andzhey; Augustinus, Andre; Averbeck, Ralf Peter; Awes, Terry; Aysto, Juha Heikki; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bailhache, Raphaelle Marie; Bala, Renu; Baldini Ferroli, Rinaldo; Baldisseri, Alberto; Baldit, Alain; Baltasar Dos Santos Pedrosa, Fernando; Ban, Jaroslav; Baral, Rama Chandra; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Barret, Valerie; Bartke, Jerzy Gustaw; Basile, Maurizio; Bastid, Nicole; Bathen, Bastian; Batigne, Guillaume; Batyunya, Boris; Baumann, Christoph Heinrich; Bearden, Ian Gardner; Beck, Hans; Belikov, Iouri; Bellini, Francesca; Bellwied, Rene; Belmont-Moreno, Ernesto; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bergmann, Cyrano; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhati, Ashok Kumar; Bianchi, Nicola; Bianchi, Livio; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Blanco, Francesco; Blanco, F; Blau, Dmitry; Blume, Christoph; Boccioli, Marco; Bock, Nicolas; Bogdanov, Alexey; Boggild, Hans; Bogolyubsky, Mikhail; Boldizsar, Laszlo; Bombara, Marek; Book, Julian; Borel, Herve; Borissov, Alexander; Bose, Suvendu Nath; Bossu, Francesco; Botje, Michiel; Bottger, Stefan; Boyer, Bruno Alexandre; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Broz, Michal; Brun, Rene; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Bugaiev, Kyrylo; Busch, Oliver; Buthelezi, Edith Zinhle; Caballero Orduna, Diego; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calvo Villar, Ernesto; Camerini, Paolo; Canoa Roman, Veronica; Cara Romeo, Giovanni; Carena, Francesco; Carena, Wisla; Carlin Filho, Nelson; Carminati, Federico; Carrillo Montoya, Camilo Andres; Casanova Diaz, Amaya Ofelia; Caselle, Michele; Castillo Castellanos, Javier Ernesto; Castillo Hernandez, Juan Francisco; Casula, Ester Anna Rita; Catanescu, Vasile; Cavicchioli, Costanza; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Charvet, Jean-Luc Fernand; Chattopadhyay, Sukalyan; Chattopadhyay, Subhasis; Cherney, Michael Gerard; Cheshkov, Cvetan; Cheynis, Brigitte; Chiavassa, Emilio; Chibante Barroso, Vasco Miguel; Chinellato, David; Chochula, Peter; Chojnacki, Marek; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Coccetti, Fabrizio; Colamaria, Fabio; Coffin, Jean-Pierre Michel; Colamaria, Fabio; Conesa Balbastre, Gustavo; Conesa del Valle, Zaida; Constantin, Paul; Contin, Giacomo; Contreras, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortese, Pietro; Cortes Maldonado, Ismael; Cosentino, Mauro Rogerio; Costa, Filippo; Cotallo, Manuel Enrique; Crescio, Elisabetta; Crochet, Philippe; Cruz Alaniz, Emilia; Cuautle, Eleazar; Cunqueiro, Leticia; Dainese, Andrea; Dalsgaard, Hans Hjersing; Danu, Andrea; Das, Indranil; Das, Kushal; Das, Debasish; Dash, Sadhana; Dash, Ajay Kumar; De, Sudipan; De Azevedo Moregula, Andrea; de Barros, Gabriel; De Caro, Annalisa; de Cataldo, Giacinto; de Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; Delagrange, Hugues; Del Castillo Sanchez, Eduardo; Deloff, Andrzej; Demanov, Vyacheslav; De Marco, Nora; Denes, Ervin; De Pasquale, Salvatore; Deppman, Airton; D'Erasmo, Ginevra; de Rooij, Raoul Stefan; Di Bari, Domenico; Dietel, Thomas; Di Giglio, Carmelo; Di Liberto, Sergio; Di Mauro, Antonio; Di Nezza, Pasquale; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Dobrowolski, Tadeusz Antoni; Dominguez, Isabel; Donigus, Benjamin; Dordic, Olja; Driga, Olga; Dubey, Anand Kumar; Ducroux, Laurent; Dupieux, Pascal; Dutta Majumdar, AK; Dutta Majumdar, Mihir Ranjan; Elia, Domenico; Emschermann, David Philip; Engel, Heiko; Erdal, Hege Austrheim; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Evans, David; Eyyubova, Gyulnara; Fabris, Daniela; Faivre, Julien; Falchieri, Davide; Fantoni, Alessandra; Fasel, Markus; Fearick, Roger Worsley; Fedunov, Anatoly; Fehlker, Dominik; Feldkamp, Linus; Felea, Daniel; Feofilov, Grigory; Fernandez Tellez, Arturo; Ferretti, Roberta; Ferretti, Alessandro; Figiel, Jan; Figueredo, Marcel; Filchagin, Sergey; Filchagin, Sergey; Fini, Rosa Ana; Fionda, Fiorella; Fiore, Enrichetta Maria; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Fragkiadakis, Michail; Frankenfeld, Ulrich Michael; Fuchs, Ulrich; Furget, Christophe; Fusco Girard, Mario; Gaardhoje, Jens Joergen; Gagliardi, Martino; Gago, Alberto; Gallio, Mauro; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Garabatos, Jose; Garcia-Solis, Edmundo; Garishvili, Irakli; Gerhard, Jochen; Germain, Marie; Geuna, Claudio; Gheata, Andrei George; Gheata, Mihaela; Ghidini, Bruno; Ghosh, Premomoy; Gianotti, Paola; Girard, Martin Robert; Giubellino, Paolo; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez, Ramon; Gonzalez Ferreiro, Elena; Gonzalez-Trueba, Laura Helena; Gonzalez-Zamora, Pedro; Gorbunov, Sergey; Goswami, Ankita; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Grajcarek, Robert; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoriev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grinyov, Boris; Grion, Nevio; Gros, Philippe; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerra Gutierrez, Cesar; Guerzoni, Barbara; Guilbaud, Maxime Rene Joseph; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Gutbrod, Hans; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Han, Byounghee; Hanratty, Luke David; Hansen, Alexander; Harmanova, Zuzana; Harris, John William; Hartig, Matthias; Hasegan, Dumitru; Hatzifotiadou, Despoina; Hayrapetyan, Arsen; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Herrmann, Norbert; Hetland, Kristin Fanebust; Hicks, Bernard; Hille, Per Thomas; Hippolyte, Boris; Horaguchi, Takuma; Hori, Yasuto; Hristov, Peter Zahariev; Hrivnacova, Ivana; Huang, Meidana; Huber, Sebastian Bernd; Humanic, Thomas; Hwang, Dae Sung; Ichou, Raphaelle; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Incani, Elisa; Innocenti, Gian Michele; Innocenti, Pier Giorgio; Ippolitov, Mikhail; Irfan, Muhammad; Ivan, Cristian George; Ivanov, Marian; Ivanov, Andrey; Ivanov, Vladimir; Ivanytskyi, Oleksii; Jacholkowski, Adam Wlodzimierz; Jacobs, Peter; Jancurova, Lucia; Jang, Haeng Jin; Jangal, Swensy Gwladys; Janik, Malgorzata Anna; Janik, Rudolf; Jayarathna, Sandun; Jena, Satyajit; Jimenez Bustamante, Raul Tonatiuh; Jirden, Lennart; Jones, Peter Graham; Jung, Hyung Taik; Jung, Won Woong; Jusko, Anton; Kaidalov, Alexei; Kakoyan, Vanik; Kalcher, Sebastian; Kalinak, Peter; Kalisky, Matus; Kalliokoski, Tuomo Esa Aukusti; Kalweit, Alexander Philipp; Kanaki, Kalliopi; Kang, Ju Hwan; Kaplin, Vladimir; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karpechev, Evgeny; Kazantsev, Andrey; Kebschull, Udo Wolfgang; Keidel, Ralf; Khan, Shuaib Ahmad; Khan, Mohisin Mohammed; Khan, Palash; Khanzadeev, Alexei; Kharlov, Yury; Kileng, Bjarte; Kim, Minwoo; Kim, Taesoo; Kim, Se Yong; Kim, Dong Jo; Kim, Jonghyun; Kim, Jin Sook; Kim, Seon Hee; Kim, Do Won; Kim, Beomkyu; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Klay, Jennifer Lynn; Klein, Jochen; Klein-Bosing, Christian; Kliemant, Michael; Kluge, Alexander; Knichel, Michael Linus; Koch, Kathrin; Kohler, Markus; Kolojvari, Anatoly; Kondratiev, Valery; Kondratyeva, Natalia; Konevskih, Artem; Korneev, Andrey; Kottachchi Kankanamge Don, Chamath; Kour, Ravjeet; Kowalski, Marek; Kox, Serge; Koyithatta Meethaleveedu, Greeshma; Kral, Jiri; Kralik, Ivan; Kramer, Frederick; Kraus, Ingrid Christine; Krawutschke, Tobias; Krelina, Michal; Kretz, Matthias; Krivda, Marian; Krizek, Filip; Krus, Miroslav; Kryshen, Evgeny; Krzewicki, Mikolaj; Kucheriaev, Yury; Kuhn, Christian Claude; Kuijer, Paul; Kurashvili, Podist; Kurepin, AB; Kurepin, A; Kuryakin, Alexey; Kushpil, Vasily; Kushpil, Svetlana; Kvaerno, Henning; Kweon, Min Jung; Kwon, Youngil; Ladron de Guevara, Pedro; Lakomov, Igor; Langoy, Rune; Lara, Camilo Ernesto; Lardeux, Antoine Xavier; La Rocca, Paola; Lazzeroni, Cristina; Lea, Ramona; Le Bornec, Yves; Lee, Ki Sang; Lee, Sung Chul; Lefevre, Frederic; Lehnert, Joerg Walter; Leistam, Lars; Lenhardt, Matthieu Laurent; Lenti, Vito; Leon, Hermes; Leon Monzon, Ildefonso; Leon Vargas, Hermes; Levai, Peter; Lien, Jorgen; Li, Xiaomei; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Liu, Lijiao; Loenne, Per-Ivar; Loggins, Vera; Loginov, Vitaly; Lohn, Stefan Bernhard; Lohner, Daniel; Loizides, Constantinos; Loo, Kai Krister; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lovhoiden, Gunnar; Lu, Xianguo; Luettig, Philipp; Lunardon, Marcello; Luo, Jiebin; Luparello, Grazia; Luquin, Lionel; Luzzi, Cinzia; Ma, Ke; Ma, Rongrong; Madagodahettige-Don, Dilan Minthaka; Maevskaya, Alla; Mager, Magnus; Mahapatra, Durga Prasad; Maire, Antonin; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Ludmila; Mal'Kevich, Dmitry; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Mangotra, Lalit Kumar; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Marin, Ana Maria; Markert, Christina; Martashvili, Irakli; Martinengo, Paolo; Martinez, Mario Ivan; Martinez Davalos, Arnulfo; Martinez Garcia, Gines; Martynov, Yevgen; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Massacrier, Laure Marie; Mastromarco, Mario; Mastroserio, Annalisa; Matthews, Zoe Louise; Matyja, Adam Tomasz; Mayani, Daniel; Mayer, Christoph; Mazer, Joel; Mazzoni, Alessandra Maria; Meddi, Franco; Menchaca-Rocha, Arturo Alejandro; Mercado Perez, Jorge; Meres, Michal; Miake, Yasuo; Michalon, Alain; Milano, Leonardo; Milosevic, Jovan; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz; Mitu, Ciprian Mihai; Mlynarz, Jocelyn; Mohanty, Bedangadas; Mohanty, Ajit Kumar; Molnar, Levente; Montano Zetina, Luis Manuel; Monteno, Marco; Montes, Esther; Moon, Taebong; Morando, Maurizio; Moreira De Godoy, Denise Aparecida; Moretto, Sandra; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhuri, Sanjib; Muller, Hans; Munhoz, Marcelo; Musa, Luciano; Musso, Alfredo; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Nattrass, Christine; Naumov, Nikolay; Navin, Sparsh; Nayak, Tapan Kumar; Nazarenko, Sergey; Nazarov, Gleb; Nedosekin, Alexander; Nicassio, Maria; Nielsen, Borge Svane; Niida, Takafumi; Nikolaev, Sergey; Nikolic, Vedran; Nikulin, Sergey; Nikulin, Vladimir; Nilsen, Bjorn Steven; Nilsson, Mads Stormo; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Novitzky, Norbert; Nyanin, Alexandre; Nyatha, Anitha; Nygaard, Casper; Nystrand, Joakim Ingemar; Ochirov, Alexander; Oeschler, Helmut Oskar; Oh, Sun Kun; Oh, Saehanseul; Oleniacz, Janusz; Oppedisano, Chiara; Ortiz Velasquez, Antonio; Ortona, Giacomo; Oskarsson, Anders Nils Erik; Ostrowski, Piotr Krystian; Otterlund, Ingvar; Otwinowski, Jacek Tomasz; Oyama, Ken; Ozawa, Kyoichiro; Pachmayer, Yvonne Chiara; Pachr, Milos; Padilla, Fatima; Pagano, Paola; Paic, Guy; Painke, Florian; Pajares, Carlos; Pal, Susanta Kumar; Pal, S; Palaha, Arvinder Singh; Palmeri, Armando; Papikyan, Vardanush; Pappalardo, Giuseppe; Park, Woo Jin; Passfeld, Annika; Pastircak, Blahoslav; Patalakha, Dmitri Ivanovich; Paticchio, Vincenzo; Pavlinov, Alexei; Pawlak, Tomasz Jan; Peitzmann, Thomas; Perales, Marianela; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitri; Perez Lara, Carlos Eugenio; Perez Lezama, Edgar; Perini, Diego; Perrino, Davide; Peryt, Wiktor Stanislaw; Pesci, Alessandro; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petran, Michal; Petris, Mariana; Petrov, Plamen Rumenov; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Piccotti, Anna; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Pitz, Nora; Piuz, Francois; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Pluta, Jan Marian; Pocheptsov, Timur; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polak, Karel; Polichtchouk, Boris; Pop, Amalia; Porteboeuf-Houssais, Sarah; Pospisil, Vladimir; Potukuchi, Baba; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puchagin, Sergey; Puddu, Giovanna; Pulvirenti, Alberto; Punin, Valery; Putis, Marian; Putschke, Jorn Henning; Quercigh, Emanuele; Qvigstad, Henrik; Rachevski, Alexandre; Rademakers, Alphonse; Radomski, Sylwester; Raiha, Tomi Samuli; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Ramirez Reyes, Abdiel; Raniwala, Sudhir; Raniwala, Rashmi; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Reichelt, Patrick; Reicher, Martijn; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riccati, Lodovico; Ricci, Renato Angelo; Richert, Tuva; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Rodriguez Cahuantzi, Mario; Roed, Ketil; Rohr, David; Rohrich, Dieter; Romita, Rosa; Ronchetti, Federico; Rosnet, Philippe; Rossegger, Stefan; Rossi, Andrea; Roukoutakis, Filimon; Roy, Pradip Kumar; Roy, Christelle Sophie; Rubio Montero, Antonio Juan; Rui, Rinaldo; Ryabinkin, Evgeny; Rybicki, Andrzej; Sadovsky, Sergey; Safarik, Karel; Sahu, Pradip Kumar; Saini, Jogender; Sakaguchi, Hiroaki; Sakai, Shingo; Sakata, Dosatsu; Salgado, Carlos Albert; Salzwedel, Jai; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sandor, Ladislav; Sandoval, Andres; Sano, Satoshi; Sano, Masato; Santo, Rainer; Santoro, Romualdo; Sarkamo, Juho Jaako; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schreiner, Steffen; Schuchmann, Simone; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; 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Steinbeck, Timm Morten; Steinpreis, Matthew; Stenlund, Evert Anders; Steyn, Gideon Francois; Stocco, Diego; Stolpovskiy, Mikhail; Strabykin, Kirill; Strmen, Peter; Suaide, Alexandre Alarcon do Passo; Subieta Vasquez, Martin Alfonso; Sugitate, Toru; Suire, Christophe Pierre; Sukhorukov, Mikhail; Sultanov, Rishat; Sumbera, Michal; Susa, Tatjana; Szanto de Toledo, Alejandro; Szarka, Imrich; Szostak, Artur Krzysztof; Tagridis, Christos; Takahashi, Jun; Tapia Takaki, Daniel Jesus; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Thader, Jochen Mathias; Thomas, Deepa; Thomas, Jim; Tieulent, Raphael Noel; Timmins, Anthony; Tlusty, David; Toia, Alberica; Torii, Hisayuki; Toscano, Luca; Tosello, Flavio; Tosello, Flavio; Traczyk, Tomasz; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ulery, Jason Glyndwr; Ullaland, Kjetil; Ulrich, Jochen; Uras, Antonio; Urban, Jozef; Urciuoli, Guido Marie; Usai, Gianluca; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; van der Kolk, Naomi; Vande Vyvre, Pierre; van Leeuwen, Marco; Vannucci, Luigi; Vargas, Aurora Diozcora; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vechernin, Vladimir; Veldhoen, Misha; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara, Sergio; Vernekohl, Don Constantin; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Vikhlyantsev, Oleg; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Viyogi, Yogendra; Vodopianov, Alexander; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; von Haller, Barthelemy; Vranic, Danilo; vrebekk, Gaute; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Vladimir; Wan, Renzhuo; Wang, Dong; Wang, Mengliang; Wang, Yifei; Wang, Yaping; Watanabe, Kengo; Wessels, Johannes; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Grzegorz Andrzej; Wilk, Alexander; Williams, Crispin; Windelband, Bernd Stefan; Xaplanteris Karampatsos, Leonidas; Yang, Hongyan; Yang, Shiming; Yasnopolsky, Stanislav; Yi, JunGyu; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-Kwon; Yoon, Jongik; Yu, Weilin; Yuan, Xianbao; Yushmanov, Igor; Zach, Cenek; Zampolli, Chiara; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zaviyalov, Nikolai; Zbroszczyk, Hanna Paulina; Zelnicek, Pierre; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Xiaoming; Zhou, You; Zhou, Daicui; Zhou, Fengchu; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zinovjev, Gennady; Zoccarato, Yannick Denis; Zynovyev, Mykhaylo

    2012-01-01

    The effect of event background fluctuations on charged particle jet reconstruction in Pb-Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV has been measured with the ALICE experiment. The main sources of non-statistical fluctuations are characterized based purely on experimental data with an unbiased method, as well as by using single high p_t particles and simulated jets embedded into real Pb-Pb events and reconstructed with the anti-kt jet finder. The influence of a low transverse momentum cut-off on particles used in the jet reconstruction is quantified by varying the minimum track p_t between 0.15 GeV/c and 2 GeV/c. For embedded jets reconstructed from charged particles with $p_t$ > 0.15 GeV/c, the uncertainty in the reconstructed jet transverse momentum due to the heavy-ion background is measured to be 11.3 GeV/c (standard deviation) for the 10% most central Pb-Pb collisions, slightly larger than the value of 11.0 GeV/c measured using the unbiased method. For a higher particle transverse momentum threshold of ...

  11. Highly Localized Acoustic Streaming and Size-Selective Submicrometer Particle Concentration Using High Frequency Microscale Focused Acoustic Fields.

    Science.gov (United States)

    Collins, David J; Ma, Zhichao; Ai, Ye

    2016-05-17

    Concentration and separation of particles and biological specimens are fundamental functions of micro/nanofluidic systems. Acoustic streaming is an effective and biocompatible way to create rapid microscale fluid motion and induce particle capture, though the >100 MHz frequencies required to directly generate acoustic body forces on the microscale have traditionally been difficult to generate and localize in a way that is amenable to efficient generation of streaming. Moreover, acoustic, hydrodynamic, and electrical forces as typically applied have difficulty manipulating specimens in the submicrometer regime. In this work, we introduce highly focused traveling surface acoustic waves (SAW) at high frequencies between 193 and 636 MHz for efficient and highly localized production of acoustic streaming vortices on microfluidic length scales. Concentration occurs via a novel mechanism, whereby the combined acoustic radiation and streaming field results in size-selective aggregation in fluid streamlines in the vicinity of a high-amplitude acoustic beam, as opposed to previous acoustic radiation induced particle concentration where objects typically migrate toward minimum pressure locations. Though the acoustic streaming is induced by a traveling wave, we are able to manipulate particles an order of magnitude smaller than possible using the traveling wave force alone. We experimentally and theoretically examine the range of particle sizes that can be captured in fluid streamlines using this technique, with rapid particle concentration demonstrated down to 300 nm diameters. We also demonstrate that locations of trapping and concentration are size-dependent, which is attributed to the combined effects of the acoustic streaming and acoustic forces.

  12. Center of Mass Energy of the Collision for two Neutral Particles in the Background of a Kerr-Newman-Taub-NUT Black Hole

    CERN Document Server

    Zakria, Ayesha

    2015-01-01

    In this paper, we investigate the center of mass energy of the collision for two neutral particles with different rest masses falling freely from rest at infinity in the background of a Kerr-Newman-Taub-NUT black hole. Further, we discuss the center of mass energy near the horizon(s) of an extremal and non-extremal Kerr-Newman-Taub-NUT black hole and show that an arbitrarily high center of mass energy is achievable under some restrictions. We will study the special case of the center of mass energy when the specific energy, specific angular momentum and Carter constant of both the particles are same.

  13. Isoprene in poplar emissions: effects on new particle formation and OH concentrations

    Directory of Open Access Journals (Sweden)

    A. Kiendler-Scharr

    2012-01-01

    Full Text Available Stress-induced volatile organic compound (VOC emissions from transgenic Grey poplar modified in isoprene emission potential were used for the investigation of photochemical secondary organic aerosol (SOA formation. In poplar, acute ozone stress induces the emission of a wide array of VOCs dominated by sesquiterpenes and aromatic VOCs. Constitutive light-dependent emission of isoprene ranged between 66 nmol m−2 s−1 in non-transgenic controls (wild type WT and nearly zero (<0.5 nmol m−2 s−1 in isoprene emission-repressed plants (line RA22, respectively. Nucleation rates of up to 3600 cm−3 s−1 were observed in our experiments. In the presence of isoprene new particle formation was suppressed compared to non-isoprene containing VOC mixtures. Compared to isoprene/monoterpene systems emitted from other plants the suppression of nucleation by isoprene was less effective for the VOC mixture emitted from stressed poplar. This is explained by the observed high efficiency of new particle formation for emissions from stressed poplar. Direct measurements of OH in the reaction chamber revealed that the steady state concentration of OH is lower in the presence of isoprene than in the absence of isoprene, supporting the hypothesis that isoprenes' suppressing effect on nucleation is related to radical chemistry. In order to test whether isoprene contributes to SOA mass formation, fully deuterated isoprene (C5D8 was added to the stress-induced emission profile of an isoprene free poplar mutant. Mass spectral analysis showed that, despite the isoprene-induced suppression of particle formation, fractions of deuterated isoprene were incorporated into the SOA. A fractional mass yield of 2.3% of isoprene was observed. Future emission changes due to land use and climate change may therefore affect both gas phase oxidation capacity and new particle number formation.

  14. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    Science.gov (United States)

    Yang, X M; Drury, C F; Reynolds, W D; Yang, J Y

    2016-01-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg(-1) soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg(-1), but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation. PMID:27251365

  15. Assessment of aerosol's mass concentrations from measured linear particle depolarization ratio (vertically resolved and simulations

    Directory of Open Access Journals (Sweden)

    A. Nemuc

    2013-06-01

    Full Text Available Multiwavelength depolarization Raman lidar measurements from Magurele, Romania are used in this study along with simulated mass-extinction efficiencies to calculate the mass concentrations profiles of different atmospheric components, due to their different depolarization contribution to the 532 nm backscatter coefficient. Linear particle depolarization ratio (δpart was computed using the relative amplification factor and the system-dependent molecular depolarization. The low depolarizing component was considered as urban/smoke, with a mean δpart of 3%, while for the high depolarizing component (mineral dust a mean δpart of 35% was assumed. For this study 11 months of lidar measurements were analyzed. Two study cases are presented in details: one for a typical Saharan dust aerosol intrusion, 10 June 2012 and one for 12 July 2012 when a lofted layer consisting of biomass burning smoke extended from 3 to 4.5 km height. Optical Properties of Aerosols and Clouds software package (OPAC classification and conversion factors were used to calculate mass concentrations. We found that calibrated depolarization measurements are critical to distinguish between smoke-reach aerosol during the winter and dust-reach aerosol during the summer, as well as between elevated aerosol layers having different origins. Good agreement was found between lidar retrievals and DREAM- Dust REgional Atmospheric Model forecasts in cases of Saharan dust. Our method was also compared against LIRIC (The Lidar/Radiometer Inversion Code and very small differences were observed.

  16. Indoor-to-outdoor particle concentration ratio model for human exposure analysis

    Science.gov (United States)

    Lee, Jae Young; Ryu, Sung Hee; Lee, Gwangjae; Bae, Gwi-Nam

    2016-02-01

    This study presents an indoor-to-outdoor particle concentration ratio (IOR) model for improved estimates of indoor exposure levels. This model is useful in epidemiological studies with large population, because sampling indoor pollutants in all participants' house is often necessary but impractical. As a part of a study examining the association between air pollutants and atopic dermatitis in children, 16 parents agreed to measure the indoor and outdoor PM10 and PM2.5 concentrations at their homes for 48 h. Correlation analysis and multi-step multivariate linear regression analysis was performed to develop the IOR model. Temperature and floor level were found to be powerful predictors of the IOR. Despite the simplicity of the model, it demonstrated high accuracy in terms of the root mean square error (RMSE). Especially for long-term IOR estimations, the RMSE was as low as 0.064 and 0.063 for PM10 and PM2.5, respectively. When using a prediction model in an epidemiological study, understanding the consequence of the modeling error and justifying the use of the model is very important. In the last section, this paper discussed the impact of the modeling error and developed a novel methodology to justify the use of the model.

  17. Suspended sediment concentration and particle size distribution, and their relationship with heavy metal content

    Indian Academy of Sciences (India)

    S H R Sadeghi; M Kiani Harchegani; H A Younesi

    2012-02-01

    This paper aims at assessing the feasibility of suspended sediment concentration (SSC) estimation by using predictor variables of heavy metal concentration (HMC, viz., iron, chromium, zinc and nickel) transported in solution and solid. The study was conducted in the Research and Educational Forest Watershed of the Tarbiat Modares University (Kojour) which comprises an area of ca. 50000 ha. For this study, suspended sediment samples were collected from the left bank of the Kojour River twice a week, as well as during runoff events from November 2007 to June 2008. The samples were then prepared through direct digestion and finally analyzed by atomic absorption spectrophotometry (AAS). The relationship between SSC and particle size distribution (PSD) were correlated with HMC by using bivariate and multivariate regression models. Proposed models were then selected based on statistical criteria. The results showed high correlation between dissolved and particulate chromium content with efficiency coefficients beyond 77% ( > 0.001). However, a lower relationship was found between SSC and nickel content. From these results, it is clearly shown that the HMC can practically be estimated by SSC in watersheds with different accuracy and vice versa. It is also understood that heavy metal pollution can be easily managed by controlling SSC.

  18. Understanding Ice Supersaturation, Particle Growth, and Number Concentration in Cirrus Clouds

    Science.gov (United States)

    Comstock, Jennifer M.; Lin, Ruei-Fong; Starr, David O'C.; Yang, Ping

    2008-01-01

    Many factors control the ice supersaturation and microphysical properties in cirrus clouds. We explore the effects of dynamic forcing, ice nucleation mechanisms, and ice crystal growth rate on the evolution and distribution of water vapor and cloud properties in nighttime cirrus clouds using a one-dimensional cloud model with bin microphysics and remote sensing measurements obtained at the Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility located near Lamont, OK. We forced the model using both large-scale vertical ascent and, for the first time, mean mesoscale velocity derived from radar Doppler velocity measurements. Both heterogeneous and homogeneous nucleation processes are explored, where a classical theory heterogeneous scheme is compared with empirical representations. We evaluated model simulations by examining both bulk cloud properties and distributions of measured radar reflectivity, lidar extinction, and water vapor profiles, as well as retrieved cloud microphysical properties. Our results suggest that mesoscale variability is the primary mechanism needed to reproduce observed quantities. Model sensitivity to the ice growth rate is also investigated. The most realistic simulations as compared with observations are forced using mesoscale waves, include fast ice crystal growth, and initiate ice by either homogeneous or heterogeneous nucleation. Simulated ice crystal number concentrations (tens to hundreds particles per liter) are typically two orders of magnitude smaller than previously published results based on aircraft measurements in cirrus clouds, although higher concentrations are possible in isolated pockets within the nucleation zone.

  19. Watershed-scale assessment of background concentrations and guidance values for heavy metals in soils from a semiarid and coastal zone of Brazil.

    Science.gov (United States)

    da Silva, Yuri Jacques Agra Bezerra; do Nascimento, Clístenes Williams Araújo; Cantalice, José Ramon Barros; da Silva, Ygor Jacques Agra Bezerra; Cruz, Cinthia Maria Cordeiro Atanázio

    2015-09-01

    Determining heavy metal background concentrations in soils is fundamental in order to support the monitoring of potentially contaminated areas. This is particularly important to areas submitted to high environmental impact where an intensive and local monitoring is required. To this end, the aim of this study was to establish background concentrations and quality reference values (QRVs) for the heavy metals Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn, As, and Hg in an environmentally impacted watershed from Brazil. Geochemical associations among Fe, Mn, and trace elements were also assessed to provide an alternative tool for establishing background concentrations. A total of one hundred and four samples comprised twenty-six composite soil samples from areas of native forest or minimal anthropic influence. Samples were digested (USEPA method 3051A), and the metals were determined by ICP-OES, except for As and Hg measured by atomic absorption spectrophotometer. Background concentrations of heavy metals in soils had the following decreasing order: Fe > Mn > Zn > Cr > Pb > Ni > Cu > As > Cd > Hg. These values were usually lower than those observed in the international and national literature. The QRVs for Ipojuca watershed followed the order (mg kg(-1)) Fe (13,020.40) > Mn (91.80) > Zn (30.12) > Cr (15.00) > Pb (13.12) > Cu (3.53) > Ni (3.30) > As (0.51) > Cd (0.08) > Hg (0.04). Significant correlation among Fe, Mn, and heavy metals shows that solubilization by the method 3051A provides a reasonable estimate for predicting background concentrations for Cd, Cr, and Cu as well as Zn, Cr, Cu, and Ni. PMID:26251062

  20. The effect of mitigation measures on size distributed mass concentrations of atmospheric particles and black carbon concentrations during the Olympic Summer Games 2008 in Beijing.

    Science.gov (United States)

    Schleicher, Nina; Norra, Stefan; Dietze, Volker; Yu, Yang; Fricker, Mathieu; Kaminski, Uwe; Chen, Yuan; Cen, Kuang

    2011-12-15

    The period of the 2008 Olympic Summer Games in Beijing can be considered as a unique opportunity to study the influences of emission reduction measures on air quality improvement. Within this study atmospheric particles of different size classes (2.5 to 80 μm) were investigated before, during, and after the Olympic Games period in order to observe and assess the success of short-term measures to mitigate extreme urban aerosol pollution and also to investigate, which particle size classes were reduced most effectively. Furthermore, black carbon (BC) concentrations in fine particles (PM(2.5)) during the source control period were compared to those of the previous years in order to investigate the decrease of combustion-derived aerosols. It is shown that besides the implemented mitigation measures precipitation decisively contributed to a considerable decrease of particulate air pollution in Beijing compared to the respective concentrations during the time directly before and after the Olympic Games, and also compared to average August concentrations during the previous years and the following year 2009. Particles of the fine fraction of the coarse mode (2.5 to 5 μm), which have a residence time in the order of several days and which, therefore, are typically transported over long distances from outside of Beijing, were less efficiently reduced than coarser particles. This indicates that long-range transport of atmospheric particles is difficult to control and that presumably the established mitigation area was not large enough to also reduce the fine fraction of the coarse mode more efficiently. Furthermore, the study showed that coarse geogenic particles, which originated to a high percentage from construction sites and resuspension processes due to traffic seemed to be reduced most efficiently during the Olympic Games period. PMID:22035559

  1. Liquid scintillators and liquefied rare gases for particle detectors. Background-determination in Double Chooz and scintillation properties of liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Martin Alexander

    2012-11-27

    Evidence for physics beyond the well-established standard model of particle physics is found in the sector of neutrino physics, in particular in neutrino oscillations, and in experimental hints requiring the presence of Dark Matter. Neutrino oscillations demand the neutrinos to be massive and at least four additional parameters, three mixing angles and one phase, are introduced. A non-vanishing value for the third mixing angle, {theta}{sub 13}, has only recently been found, amongst others by the reactor antineutrino disappearance experiment Double Chooz. This experiment detects anti {nu}{sub e}'s by means of the Inverse Beta Decay (IBD), which has a clear signature that can very effectively be discriminated from most of the background. However, some background still survives the selection cuts applied to the data, partly induced by radioactivity. In order to determine the amount of radioimpurities in the detector, germanium spectroscopy measurements and neutron activation analyses have been carried out for various parts of the Double Chooz far detector. A dedicated Monte-Carlo simulation was performed to obtain the singles event rate induced by the identified radioimpurities in the fiducial volume of Double Chooz. In the present thesis, parts from the outer detector systems, as well as components of the inner detector liquids were measured. In sum, a singles rate of less than 0.35 Hz above the antineutrino detection threshold of 0.7 MeV has been found. This is by far below the design goal of Double Chooz of {proportional_to} 20 Hz. The analysis of bismuth-polonium (BiPo) coincidences in the first Double Chooz data allows to directly determine the number of decays from the U- and the Th-decay chain in the active detector parts. Assuming radioactive equilibrium, concentrations of (1.71{+-}0.08).10{sup -14}(g)/(g) for uranium and (8.16{+-}0.49).10{sup -14}(g)/(g) for thorium have been found, which are also well below the design goal of Double Chooz (2.10{sup -13

  2. Liquid scintillators and liquefied rare gases for particle detectors. Background-determination in Double Chooz and scintillation properties of liquid argon

    International Nuclear Information System (INIS)

    Evidence for physics beyond the well-established standard model of particle physics is found in the sector of neutrino physics, in particular in neutrino oscillations, and in experimental hints requiring the presence of Dark Matter. Neutrino oscillations demand the neutrinos to be massive and at least four additional parameters, three mixing angles and one phase, are introduced. A non-vanishing value for the third mixing angle, θ13, has only recently been found, amongst others by the reactor antineutrino disappearance experiment Double Chooz. This experiment detects anti νe's by means of the Inverse Beta Decay (IBD), which has a clear signature that can very effectively be discriminated from most of the background. However, some background still survives the selection cuts applied to the data, partly induced by radioactivity. In order to determine the amount of radioimpurities in the detector, germanium spectroscopy measurements and neutron activation analyses have been carried out for various parts of the Double Chooz far detector. A dedicated Monte-Carlo simulation was performed to obtain the singles event rate induced by the identified radioimpurities in the fiducial volume of Double Chooz. In the present thesis, parts from the outer detector systems, as well as components of the inner detector liquids were measured. In sum, a singles rate of less than 0.35 Hz above the antineutrino detection threshold of 0.7 MeV has been found. This is by far below the design goal of Double Chooz of ∝ 20 Hz. The analysis of bismuth-polonium (BiPo) coincidences in the first Double Chooz data allows to directly determine the number of decays from the U- and the Th-decay chain in the active detector parts. Assuming radioactive equilibrium, concentrations of (1.71±0.08).10-14(g)/(g) for uranium and (8.16±0.49).10-14(g)/(g) for thorium have been found, which are also well below the design goal of Double Chooz (2.10-13(g)/(g)). Both gamma spectroscopy measurements and the Bi

  3. Long-term aerosol measurements in Gran Canaria, Canary Islands: Particle concentration, sources and elemental composition

    Science.gov (United States)

    Gelado-Caballero, MaríA. D.; López-GarcíA, Patricia; Prieto, Sandra; Patey, Matthew D.; Collado, Cayetano; HéRnáNdez-Brito, José J.

    2012-02-01

    There are very few sets of long-term measurements of aerosol concentrations over the North Atlantic Ocean, yet such data is invaluable in quantifying atmospheric dust inputs to this ocean region. We present an 8-year record of total suspended particles (TSP) collected at three stations on Gran Canaria Island, Spain (Taliarte at sea level, Tafira 269 m above sea level (a.s.l.) and Pico de la Gorra 1930 m a.s.l.). Using wet and dry deposition measurements, the mean dust flux was calculated at 42.3 mg m-2 d-1. Air mass back trajectories (HYSPLIT, NOAA) suggested that the Sahara desert is the major source of African dust (dominant during 32-50% of days), while the Sahel desert was the major source only 2-10% of the time (maximum in summer). Elemental composition ratios of African samples indicate that, despite the homogeneity of the dust in collected samples, some signatures of the bedrocks can still be detected. Differences were found for the Sahel, Central Sahara and North of Sahara regions in Ti/Al, Mg/Al and Ca/Al ratios, respectively. Elements often associated with pollution (Pb, Cd, Ni, Zn) appeared to share a common origin, while Cu may have a predominantly local source, as suggested by a decrease in the enrichment factor (EF) of Cu during dust events. The inter-annual variability of dust concentrations is investigated in this work. During winter, African dust concentration measurements at the Pico de la Gorra station were found to correlate with the North Atlantic Oscillation (NAO) index.

  4. Establishment of natural background concentration of some elements in soils from Zaria and environ by INAA using NIRR-1

    International Nuclear Information System (INIS)

    Source profile of chemical elements is important both for determination of natural baseline and anthropogenic input into soil characteristics. Undisturbed soils in Zaria and environ were sampled at six locations namely Bassawa, Kufena, TSibiri, Palladan, Kamphaghi and Kudingi based on the geology of the area. The soil samples were analyzed for sixteen (16) elements using Instrumental Neutron Activation Analysis (INAA) Technique. The elements determined were AI, Mn, Dy, K, Br, La, Sc, Cr, Fe, Co, Rb, Cs, Ba, Eu, Lu and Ta. Analysis of the data revealed that concentration of most of the elements determined increases with depth indicating that natural sources account for the distribution pattern. In addition, soil samples collected in areas underlain by igneous rocks contain high concentrations of AI and Dy in 0-15 cm fraction and K, La, Rb and Mn in 0-30 cm fraction when compared with soil samples collected in areas underlain by metamorphic rocks. On the other hand, soil collected from the areas underlain by metamorphic rocks are more enriched in Sc and Cr in the 0-15 cm fraction and Sc and Co in the 0-30 cm fraction compared with soil collected from areas underlain by igneous rocks. The general variations in the elemental concentration of the various soil samples is attributed to the differences in parent rock chemistry and constituent minerals, local variation in Eh-pH conditions of the environment and continued alterations by other soil forming factors.

  5. Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site

    Directory of Open Access Journals (Sweden)

    G. Calzolai

    2012-08-01

    Full Text Available Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban Environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb were obtained by time (1 h and size (PM2.5 particulate matter 2.5 fraction simultaneously measured at the UB and RS sites: (1 the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2 by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3 a unique source of Pb-Cl (associated with industrial combustion emissions is found a to be the major (82% source of Cl in the urban agglomerate; (4 PM2.5 traffic brake dust (Fe-Cu is mainly primarily emitted and not resuspended, whereas PM2.5 urban crustal dust (Ca is found mainly resuspended by both traffic vortex and sea breeze; (5 urban dust (Ca is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing dust concentrations in road sites, far more effective than street sweeping activities.

  6. On the simultaneous deployment of two single-particle mass spectrometers at an urban background and a roadside site during SAPUSS

    Science.gov (United States)

    Dall'Osto, Manuel; Beddows, David C. S.; McGillicuddy, Eoin J.; Esser-Gietl, Johanna K.; Harrison, Roy M.; Wenger, John C.

    2016-08-01

    The aerosol time-of-flight mass spectrometer (ATOFMS) provides size-resolved information on the chemical composition of single particles with high time resolution. Within SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies), continuous ATOFMS measurements of ambient particles were made simultaneously at two urban locations: urban background (UB) site and roadside (RS) site in the city of Barcelona (Spain) from 17 September to 18 October 2010. Two different instrumental configurations were used: ATOFMS (TSI 3800) with a converging nozzle inlet (high efficiency at about 800-2000 nm) at the UB site and ATOFMS (TSI 3800-100) with an aerodynamic lens inlet (high efficiency at about 300-700 nm) at the RS site. This is the first time, to our knowledge, that two ATOFMS instruments have been deployed in the same field study. The different instrument configurations had an impact on the observed particle types at the two sites. Nevertheless, 10 particle types were detected at both locations, including local and regional elemental carbon (22.7-58.9 % of total particles), fresh and aged sea salt (1.0-14.6 %), local and regional nitrate-containing aerosols (3-11.6 %), local lead-containing metallic particles (0.1-0.2 %), and transported Fe-nitrate particles (0.8-2.5 %). The ATOFMS at the UB also characterized four particle types: calcium-containing dust (0.9 %), Saharan dust (1.3 %), vanadium-containing particles (0.9 %), and vegetative debris (1.7 %). By contrast, the high statistical counts of fine particles detected at the RS allowed identification of eight particle types. Four of these contained organic nitrogen of primary and secondary origin, which highlights the complex nature of the sources and processes that contribute to this aerosol chemical component. Aminium salts were found related to coarse sulfate-rich particle types, suggesting heterogeneous reaction mechanisms for their formation. The other four particle types mainly containing organic carbon were

  7. Giant in-particle field concentration and Fano resonances at light scattering by high-refractive-index particles

    Science.gov (United States)

    Tribelsky, Michael I.; Miroshnichenko, Andrey E.

    2016-05-01

    We present the results of a detailed analytical study of light scattering by a particle with high refractive index m +i κ and low losses (m ≫1 ,0 academic interest, the obtained results may be employed to design new highly nonlinear heterogenic nanostructures and other metamaterials.

  8. ZnO film with ultra-low background electron concentration grown by plasma-assisted MBE using Mg film as the buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Mingming; Zhang, Quanlin; Su, Longxing; Su, Yuquan; Cao, Jiashi; Zhu, Yuan; Wu, Tianzhun; Gui, Xuchun [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou (China); Yang, Chunlei [Center for Photovoltaics and Solar Energy, Shen Zhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shen Zhen (China); Xiang, Rong, E-mail: xiangr2@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou (China); Tang, Zikang, E-mail: phzktang@ust.hk [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou (China); Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

    2012-09-15

    Highlights: ► High quality ZnO film with ultra-low background electron concentration is grown by plasma-assisted molecular beam epitaxy using Mg film as a buffer layer. ► High resolution X-ray diffraction and photoluminescence (PL) spectroscopy indicate a high degree of crystallization. ► Hall measurement shows a carrier concentration as low as ∼10{sup 14} cm{sup −3}. ► The mechanism of the improved crystallinity is discussed in detail. -- Abstract: High quality ZnO epilayer with background electron concentration as low as 2.6 × 10{sup 14} cm{sup −3} was obtained by plasma-assisted MBE on c-sapphire using a thin Mg film as the buffer layer. High-resolution XRD measurement shows a sharp (0 0 2) peak with full width at half maximum (FWHM) of only 0.029°. Photoluminescence spectroscopy presents a weak defect-related near-edge emission. A metal–semiconductor–metal (MSM) typed photodetector based on the material demonstrates a response of ∼43 A/W under the bias of 1 V and an ON/OFF ratio of 10{sup 4}. This un-doped ZnO with ultra-low background electron concentration could be a promising starting material for p-type doping.

  9. Particle concentration effect in adsorption/desorption of Zn(II) on anatase type nano TiO2

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Adsorption/desorption in a new Zn(II)-TiO2 adsorption system was investigated at different particle concentrations (Cp). TEM, SEM and XRD analyses revealed that the TiO2 particles were an aggregation of nano-sized (approximately 10 nm) pure anatase-type TiO2. Adsorption experiments were carried out with particle concentrations of 100, 400 and 1000 mg/L, and their adsorption isotherms were found to decline successively, showing an obvious Cp effect. Desorption experiments indicated that adsorption in this system was irreversible, and the irreversibility increased with increasing Cp. These phenomena could be explained by the MEA (metastable equilibrium adsorption) theory and the Cp effect could be modeled well with an MEA-Freundlich-type Cp effect isotherm equation. This study may help understand environmental behavior of contaminants on ultrafine natural particles.

  10. Improving the $t\\bar t+$jets background rejection in a search for supersymmetric particles in events with leptons and multiple jets at the ATLAS experiment

    CERN Document Server

    Guenther, Paul Andre

    2016-01-01

    In this report, an attempt to select $b$-quark pairs from $g\\rightarrow b\\bar b$ in the $t\\bar t+$jets background simulation of a search for supersymmetric particles in events with leptons and multiple jets is presented. $b$-tagged jets are paired and selected exploiting kinematic differences between these from gluon-splitting and mainly those from top quark decays. It is found that $(33\\pm3)\\%$ of the built pairs from the background in the signal region consist of two $b$-tagged jets from gluon-splitting. No large improvement of the signal-to-background ratio can be achieved from this. The fraction of built $b$-tagged jet pairs that originate from a gluon can be increased to above $60\\%$ with a cut on a discriminating variable.

  11. Ice crystal concentrations in wave clouds: dependencies on temperature, D0.5 μm aerosol particle concentration and duration of cloud processing

    Directory of Open Access Journals (Sweden)

    L. Peng

    2014-10-01

    Full Text Available Model equations used to either diagnose or prognose the concentration of heterogeneously nucleated ice crystals depend on combinations of cloud temperature, aerosol properties, and elapsed time of supersaturated-vapor or supercooled-liquid conditions. The validity of these equations is questioned. For example, there is concern that practical limitations on aerosol particle time-of-exposure to supercooled-liquid conditions, within ice nucleus counters, can bias model equations that have been constrained by ice nuclei (IN measurements. In response to this concern, this work analyzes airborne measurements of crystals made within the downwind glaciated portions of middle-tropospheric wave clouds. A streamline model is used to connect a measurement of aerosol concentration, made upwind of a cloud, to a downwind ice crystal (IC concentration. Four parameters were derived for 80 streamlines: (1 minimum cloud temperature along the streamline, (2 aerosol particle concentration (diameter, D>0.5 μm measured within ascending air, upwind of the cloud, (3 IC concentration measured in descending air downwind, and (4 the duration of water-saturated conditions along the streamline. The latter are between 38 to 507 s and the minimum temperatures are between −34 to −14 °C. Values of minimum temperature, D>0.5 μm aerosol concentration and IC concentration were fitted using the equation developed for IN by DeMott et al. (2010; D10. Overall, there is reasonable agreement among measured IC concentrations, IN concentrations derived using D10's fit equation, and IC concentrations derived by fitting the wave cloud measurements with the equation developed by D10.

  12. New LWR Fuel Assembly Concepts using Particle Burnable Poisons for Low Boron Concentration

    International Nuclear Information System (INIS)

    The most importance role of the soluble boron is the control of the long term reactivity to maintain the criticality of the reactor cores by reducing core excess reactivity. However, the use of soluble boron in the coolant leads to several issues. First, boron is corrosive and the presence of boron in the coolant will increase corrosion on the primary coolant loop and the corrosive nuclides will be mixed with the coolant. Furthermore, CVCS (Chemical and Volume Control System) is required to clean these corrosive elements from the coolant and to purify and control the level of boron diluted in the coolant. The presence of CVCS including the corrosive elements requires complicated maintenance and operation leading to increases of additional pipes which can add the possibilities of occurrences of LOCAs (Loss of Coolant Accident). Furthermore, the removal of soluble boron or reduction of soluble boron concentration makes the moderator temperature coefficient (MTC) more negative. In this paper, we suggest use of burnable poison rods where burnable poison particles are distributed in the SiC matrix as in the FCM (Fully Ceramic Micro-encapsulated) fuel and we performed a feasibility study on the use of the new LWR fuel assembly design concepts using this concept of new burnable poison rods to achieve low boron or boron-free cores

  13. High concentrations of biological aerosol particles and ice nuclei during and after rain

    Science.gov (United States)

    Huffman, J. A.; Prenni, A. J.; DeMott, P. J.; Pöhlker, C.; Mason, R. H.; Robinson, N. H.; Fröhlich-Nowoisky, J.; Tobo, Y.; Després, V. R.; Garcia, E.; Gochis, D. J.; Harris, E.; Müller-Germann, I.; Ruzene, C.; Schmer, B.; Sinha, B.; Day, D. A.; Andreae, M. O.; Jimenez, J. L.; Gallagher, M.; Kreidenweis, S. M.; Bertram, A. K.; Pöschl, U.

    2013-07-01

    Bioaerosols are relevant for public health and may play an important role in the climate system, but their atmospheric abundance, properties, and sources are not well understood. Here we show that the concentration of airborne biological particles in a North American forest ecosystem increases significantly during rain and that bioparticles are closely correlated with atmospheric ice nuclei (IN). The greatest increase of bioparticles and IN occurred in the size range of 2-6 μm, which is characteristic for bacterial aggregates and fungal spores. By DNA analysis we found high diversities of airborne bacteria and fungi, including groups containing human and plant pathogens (mildew, smut and rust fungi, molds, Enterobacteriaceae, Pseudomonadaceae). In addition to detecting known bacterial and fungal IN (Pseudomonas sp., Fusarium sporotrichioides), we discovered two species of IN-active fungi that were not previously known as biological ice nucleators (Isaria farinosa and Acremonium implicatum). Our findings suggest that atmospheric bioaerosols, IN, and rainfall are more tightly coupled than previously assumed.

  14. Long-term observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN

    Directory of Open Access Journals (Sweden)

    W. Birmili

    2015-11-01

    Full Text Available The German Ultrafine Aerosol Network (GUAN is a cooperative atmospheric observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both, climate and health related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at seventeen observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained (doi:10.5072/guan.

  15. Long-term observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN)

    Science.gov (United States)

    Birmili, Wolfram; Weinhold, Kay; Rasch, Fabian; Sonntag, André; Sun, Jia; Merkel, Maik; Wiedensohler, Alfred; Bastian, Susanne; Schladitz, Alexander; Löschau, Gunter; Cyrys, Josef; Pitz, Mike; Gu, Jianwei; Kusch, Thomas; Flentje, Harald; Quass, Ulrich; Kaminski, Heinz; Kuhlbusch, Thomas A. J.; Meinhardt, Frank; Schwerin, Andreas; Bath, Olaf; Ries, Ludwig; Wirtz, Klaus; Fiebig, Markus

    2016-08-01

    The German Ultrafine Aerosol Network (GUAN) is a cooperative atmospheric observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both climate- and health-related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at 17 observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance, and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained (doi:10.5072/guan).

  16. Impacts of biochar concentration and particle size on hydraulic conductivity and DOC leaching of biochar-sand mixtures

    Science.gov (United States)

    Liu, Zuolin; Dugan, Brandon; Masiello, Caroline A.; Barnes, Rebecca T.; Gallagher, Morgan E.; Gonnermann, Helge

    2016-02-01

    The amendment of soil with biochar can sequester carbon and alter hydrologic properties by changing physical and chemical characteristics of soil. To understand the effect of biochar amendment on soil hydrology, we measured the hydraulic conductivity (K) of biochar-sand mixtures as well as dissolved organic carbon (DOC) in leachate. Specifically, we assessed the effects of biochar concentration and particle size on K and amount of DOC in the soil leachate. To better understand how physical properties influenced K, we also measured the skeletal density of biochars and sand, and the bulk density, the water saturation, and the porosity of biochar-sand mixtures. Our model soil was sand (0.251-0.853 mm) with biochar rates from 2 to 10 wt% (g biochar/g total soil × 100%). As biochar (concentration increased from 0 to 10 wt%, K decreased by 72 ± 3%. When biochar particle size was equal to, greater than, and less than particle size of sand, we found that biochar in different particle sizes have different effects on K. For a 2 wt% biochar rate, K decreased by 72 ± 2% when biochar particles were finer than sand particles, and decreased by 15 ± 2% when biochar particles were coarser than sand particles. When biochar and sand particle size were comparable, we observed no significant effect on K. We propose that the decrease of K through the addition of fine biochar was because finer biochar particles filled spaces between sand particles, which increased tortuosity and reduced pore throat size of the mixture. The decrease of K associated with coarser biochar was caused by the bimodal particle size distribution, resulting in more compact packing and increased tortuosity. The loss of biochar C as DOC was related to both biochar rate and particle size. The cumulative DOC loss was 1350% higher from 10 wt% biochar compared to pure sand. This large increase reflected the very small DOC yield from pure sand. In addition, DOC in the leachate decreased as biochar particle size

  17. Concentrations and their ratio of (222)Rn decay products in rainwater measured by gamma-ray spectrometry using a low-background Ge detector.

    Science.gov (United States)

    Takeyasu, Masanori; Iida, Takao; Tsujimoto, Tadashi; Yamasaki, Keizo; Ogawa, Yoshihiro

    2006-01-01

    The concentrations and the concentration ratios of individual short-lived (222)Rn decay products ((214)Pb and (214)Bi) in rainwater were measured at Kumatori village (34.39 degrees N, 135.35 degrees E, approximately 70 m above sea level) in Osaka, Japan, by gamma-ray spectrometry using a low-background Ge detector. The dependence of the time variations of the concentrations and their ratios on rainfall rate was investigated. It was observed that the concentrations were negatively correlated with the rainfall rate in some rainfall events, and that there was no clear correlation in other rainfall events. The changes in the dependence of the concentration on the rainfall rate occurred after the passage of a cold front during a single rainfall event. The concentration ratios showed a weak negative correlation with the rainfall rate for most of the observed rainfall events. A scavenging model was designed in this study in order to explain the observation results. Based on the relationship between the concentrations of (214)Pb and (214)Bi in the rainwater and the rainfall rate for an individual rainfall event, the increase in the environmental gamma-ray dose rate from (214)Pb and (214)Bi deposited on the ground was calculated, and the calculated increase agreed well with that observed by the in situ measurement on flat ground. PMID:16530896

  18. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    Science.gov (United States)

    Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

    2016-06-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg‑1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation.

  19. Enhancing Signal Output and Avoiding BOD/Toxicity Combined Shock Interference by Operating a Microbial Fuel Cell Sensor with an Optimized Background Concentration of Organic Matter.

    Science.gov (United States)

    Jiang, Yong; Liang, Peng; Liu, Panpan; Bian, Yanhong; Miao, Bo; Sun, Xueliang; Zhang, Helan; Huang, Xia

    2016-01-01

    In the monitoring of pollutants in an aquatic environment, it is important to preserve water quality safety. Among the available analysis methods, the microbial fuel cell (MFC) sensor has recently been used as a sustainable and on-line electrochemical microbial biosensor for biochemical oxygen demand (BOD) and toxicity, respectively. However, the effect of the background organic matter concentration on toxicity monitoring when using an MFC sensor is not clear and there is no effective strategy available to avoid the signal interference by the combined shock of BOD and toxicity. Thus, the signal interference by the combined shock of BOD and toxicity was systematically studied in this experiment. The background organic matter concentration was optimized in this study and it should be fixed at a high level of oversaturation for maximizing the signal output when the current change (ΔI) is selected to correlate with the concentration of a toxic agent. When the inhibition ratio (IR) is selected, on the other hand, it should be fixed as low as possible near the detection limit for maximizing the signal output. At least two MFC sensors operated with high and low organic matter concentrations and a response chart generated from pre-experiment data were both required to make qualitative distinctions of the four types of combined shock caused by a sudden change in BOD and toxicity.

  20. Enhancing Signal Output and Avoiding BOD/Toxicity Combined Shock Interference by Operating a Microbial Fuel Cell Sensor with an Optimized Background Concentration of Organic Matter.

    Science.gov (United States)

    Jiang, Yong; Liang, Peng; Liu, Panpan; Bian, Yanhong; Miao, Bo; Sun, Xueliang; Zhang, Helan; Huang, Xia

    2016-01-01

    In the monitoring of pollutants in an aquatic environment, it is important to preserve water quality safety. Among the available analysis methods, the microbial fuel cell (MFC) sensor has recently been used as a sustainable and on-line electrochemical microbial biosensor for biochemical oxygen demand (BOD) and toxicity, respectively. However, the effect of the background organic matter concentration on toxicity monitoring when using an MFC sensor is not clear and there is no effective strategy available to avoid the signal interference by the combined shock of BOD and toxicity. Thus, the signal interference by the combined shock of BOD and toxicity was systematically studied in this experiment. The background organic matter concentration was optimized in this study and it should be fixed at a high level of oversaturation for maximizing the signal output when the current change (ΔI) is selected to correlate with the concentration of a toxic agent. When the inhibition ratio (IR) is selected, on the other hand, it should be fixed as low as possible near the detection limit for maximizing the signal output. At least two MFC sensors operated with high and low organic matter concentrations and a response chart generated from pre-experiment data were both required to make qualitative distinctions of the four types of combined shock caused by a sudden change in BOD and toxicity. PMID:27563887

  1. Enhancing Signal Output and Avoiding BOD/Toxicity Combined Shock Interference by Operating a Microbial Fuel Cell Sensor with an Optimized Background Concentration of Organic Matter

    Directory of Open Access Journals (Sweden)

    Yong Jiang

    2016-08-01

    Full Text Available In the monitoring of pollutants in an aquatic environment, it is important to preserve water quality safety. Among the available analysis methods, the microbial fuel cell (MFC sensor has recently been used as a sustainable and on-line electrochemical microbial biosensor for biochemical oxygen demand (BOD and toxicity, respectively. However, the effect of the background organic matter concentration on toxicity monitoring when using an MFC sensor is not clear and there is no effective strategy available to avoid the signal interference by the combined shock of BOD and toxicity. Thus, the signal interference by the combined shock of BOD and toxicity was systematically studied in this experiment. The background organic matter concentration was optimized in this study and it should be fixed at a high level of oversaturation for maximizing the signal output when the current change (ΔI is selected to correlate with the concentration of a toxic agent. When the inhibition ratio (IR is selected, on the other hand, it should be fixed as low as possible near the detection limit for maximizing the signal output. At least two MFC sensors operated with high and low organic matter concentrations and a response chart generated from pre-experiment data were both required to make qualitative distinctions of the four types of combined shock caused by a sudden change in BOD and toxicity.

  2. Influence of the ammonium hydroxide concentration in morphological control of meso porous silica particles

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sukbon; Jung, Chonghun; Yoon, Inho; Kim, Changki; Choi, Wangkyu; Moon, Jeikwon [Division of Decontamination and Decommissioning Technology Development, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-10-15

    The discovery of new M41S meso porous silica families in 1992 extended the applications into much wider pore ranges, bringing in a new prosperous era in porous material research. The synthesis of these meso porous silicas has been mainly accomplished through a self-assembly between surfactant molecules and inorganic species under various pH conditions. Meanwhile, many studies have been conducted on the application as catalysts, adsorbents, and packing materials for separation columns due to their unique properties such as high specific surface area, large pore volume, tuneable pore size, and narrow pore size distribution. The pore sizes of these materials can be easily controlled by changing the alkyl-chain length of the surfactant used. However, the control of the morphology and the pore structure is not so common. The morphological control of these materials in particular is one of the major challenges for their industrial application. Recently, the meso porous silica materials with various shapes such as fibers, films, polyhedral particles, and spheres have been reported. In our previous study, the core-shell nanoparticles with a silica core and a meso porous shell under basic conditions were synthesized using the silica nanoparticles as a core and tetraethyl orthosilicate (TEOS)-cetyltrimethylammonium bromide (CTABr)-NH{sub 4}OH-H{sub 2}O-C{sub 2}H{sub 5}OH system. In this work, we report the synthesis of the most well known hexagonal MCM-41 among three main mesophases in the M41S families using TEOS-CTABr-NH{sub 4}OH-H{sub 2}O system. Also, in the control of the morphology and pore structure of the meso porous silica materials, the influence of the NH{sub 4}OH concentration was investigated.

  3. Characterization of gas/particle concentrations and partitioning of polychlorinated biphenyls (PCBs) measured in an urban site of Turkey

    International Nuclear Information System (INIS)

    Air concentrations of polychlorinated biphenyls (PCBs) in both gas and particle phases were measured in an urban site (BUTAL-Merinos) of the city of Bursa, Turkey between August 2004 and May 2005. The mean of total (particle + gas) PCB concentrations was about 491.8 ± 189.4 pg/m3. The main contributors for PCBs in the sampling site were the local sources and long-range atmospheric transport supported by back trajectory analysis. Lower molecular weight PCB congeners generally dominated in the samples. The particle phase of the measured PCBs accounted for 15% of the total PCB concentrations. Gas/particle distribution was investigated using different approaches such as log K P -log P Lo, log K P -log K OA and the Junge-Pankow model. Regression analysis among log K P, log P Lo and log K OA exhibited significant correlation at p < 0.05. Correlation between PCB homologs and meteorological parameters was formed to investigate the possible relationships. - Atmospheric PCBs including particle and gas phases, homolog distribution, partitioning characteristics and relationship with air transport were investigated

  4. Characterization of the inter-annual, seasonal, and diurnal variations of condensation particle concentrations at Neumayer, Antarctica

    Directory of Open Access Journals (Sweden)

    R. Weller

    2011-07-01

    Full Text Available Continuous condensation particle (CP observations were conducted from 1984 through 2009 at Neumayer Station under stringent contamination control. During this period, the CP concentration (median 258 cm−3 showed no significant long term trend but exhibited a pronounced seasonality characterized by a stepwise increase starting in September and reaching its annual maximum of around 103 cm−3 in March. Minimum values below 102 cm−3 were observed during June/July. Dedicated time series analyses in the time and frequency domain revealed no significant correlations between inter-annual CP concentration variations and atmospheric circulation indices like Southern Annular Mode (SAM or Southern Ocean Index (SOI. The impact of the Pinatubo volcanic eruption and strong El Niño events did not affect CP concentrations. From thermodenuder experiments we deduced that the portion of volatile (at 125 °C and semi-volatile (at 250 °C particles which could be both associated with biogenic sulfur aerosol, was maximum during austral summer, while during winter non-volatile sea salt particles dominated. During September through April we could frequently detect nucleation events which occurred preferentially in the afternoon. Over the year, roughly 20 % of the particles could be assigned to the nucleation mode between 3 nm and 7 nm particle diameter.

  5. Tangential Flow Ultrafiltration Allows Purification and Concentration of Lauric Acid-/Albumin-Coated Particles for Improved Magnetic Treatment.

    Science.gov (United States)

    Zaloga, Jan; Stapf, Marcus; Nowak, Johannes; Pöttler, Marina; Friedrich, Ralf P; Tietze, Rainer; Lyer, Stefan; Lee, Geoffrey; Odenbach, Stefan; Hilger, Ingrid; Alexiou, Christoph

    2015-08-14

    Superparamagnetic iron oxide nanoparticles (SPIONs) are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEON(LA-BSA), which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEON(LA-BSA) particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v). Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEON(LA-BSA) changed only marginally. The specific absorption rate (SAR) was not greatly affected by concentration. In contrast, the maximum temperature Tmax in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment.

  6. Tangential Flow Ultrafiltration Allows Purification and Concentration of Lauric Acid-/Albumin-Coated Particles for Improved Magnetic Treatment.

    Science.gov (United States)

    Zaloga, Jan; Stapf, Marcus; Nowak, Johannes; Pöttler, Marina; Friedrich, Ralf P; Tietze, Rainer; Lyer, Stefan; Lee, Geoffrey; Odenbach, Stefan; Hilger, Ingrid; Alexiou, Christoph

    2015-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEON(LA-BSA), which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEON(LA-BSA) particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v). Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEON(LA-BSA) changed only marginally. The specific absorption rate (SAR) was not greatly affected by concentration. In contrast, the maximum temperature Tmax in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment. PMID:26287178

  7. Tangential Flow Ultrafiltration Allows Purification and Concentration of Lauric Acid-/Albumin-Coated Particles for Improved Magnetic Treatment

    Directory of Open Access Journals (Sweden)

    Jan Zaloga

    2015-08-01

    Full Text Available Superparamagnetic iron oxide nanoparticles (SPIONs are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEONLA-BSA, which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEONLA-BSA particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v. Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEONLA-BSA changed only marginally. The specific absorption rate (SAR was not greatly affected by concentration. In contrast, the maximum temperature Tmax in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment.

  8. Prediction of particle formation and number concentration over the United States with WRF-Chem + APM model

    Science.gov (United States)

    Luo, G.; Yu, F.

    2010-12-01

    Aerosol nucleation events have been widely observed at various locations around the world and well recognized to dominate the particle number abundance and cloud condensation nuclei concentrations in many parts of the troposphere. An advanced particle microphysics model (APM), which has been previously incorporated into a global chemistry transport model (GEOS-Chem) and validated against a large set of aerosol measurements (Yu and Luo, 2009; Yu et al., 2010), has been successfully integrated into the Weather Research and Forecast model coupled with Chemistry (WRF-Chem). The size-resolved (sectional) APM model, which distinguishes secondary and primary particles and keeps track of the amount of secondary species coated on each type of primary particles (black carbon, primary organic carbon, dust, and sea salt), is designed to capture key particle properties important for their health and climatic effects while keep the computing cost at a reasonable level. WRF-Chem has 53 tracers for CBM-Z mechanism, and it took 2.2 hours for one day simulations covering a region of 3780×2916 km2 with 27 km horizontal resolutions and 34 layers on an 8-CPU Linux workstation (2.2 Ghz Dual Quad-Core AMD Opteron Processor 2354). The coupled WRF-Chem-APM model has 138 tracers (85 additional tracers associated with APM), and it took 5.02 hours on the same machine for same day simulation with full size-resolved microphysics (nucleation, condensation, coagulation, deposition, and scavenging) and CBM-Z chemistry. The WRF-Chem + APM has been employed to study the formation and growth of particles over the United States, using relevant outputs from GEOS-Chem + APM as initial conditions and boundary conditions. We show that ion-mediated nucleation of sulfuric acid and water can lead to significant new particle formation over the United States and nucleation rates have strongly spatial and temporal variations. The simulated spatial (both horizontal and vertical) distribution of particle

  9. Effect of type and concentration of ballasting particles on sinking rate of marine snow produced by the appendicularian Oikopleura dioica.

    Directory of Open Access Journals (Sweden)

    Fabien Lombard

    Full Text Available Ballast material (organic, opal, calcite, lithogenic is suggested to affect sinking speed of aggregates in the ocean. Here, we tested this hypothesis by incubating appendicularians in suspensions of different algae or Saharan dust, and observing the sinking speed of the marine snow formed by their discarded houses. We show that calcite increases the sinking speeds of aggregates by ~100% and lithogenic material by ~150% while opal only has a minor effect. Furthermore the effect of ballast particle concentration was causing a 33 m d(-1 increase in sinking speed for a 5×10(5 µm(3 ml(-1 increase in particle concentration, near independent on ballast type. We finally compare our observations to the literature and stress the need to generate aggregates similar to those in nature in order to get realistic estimates of the impact of ballast particles on sinking speeds.

  10. Effect of type and concentration of ballasting particles on sinking rate of marine snow produced by the appendicularian Oikopleura dioica.

    Science.gov (United States)

    Lombard, Fabien; Guidi, Lionel; Kiørboe, Thomas

    2013-01-01

    Ballast material (organic, opal, calcite, lithogenic) is suggested to affect sinking speed of aggregates in the ocean. Here, we tested this hypothesis by incubating appendicularians in suspensions of different algae or Saharan dust, and observing the sinking speed of the marine snow formed by their discarded houses. We show that calcite increases the sinking speeds of aggregates by ~100% and lithogenic material by ~150% while opal only has a minor effect. Furthermore the effect of ballast particle concentration was causing a 33 m d(-1) increase in sinking speed for a 5×10(5) µm(3) ml(-1) increase in particle concentration, near independent on ballast type. We finally compare our observations to the literature and stress the need to generate aggregates similar to those in nature in order to get realistic estimates of the impact of ballast particles on sinking speeds. PMID:24086610

  11. Radial pressure in the solar nebula as affecting the motions of planetesimals. [toroidal particle concentration in planetary evolution

    Science.gov (United States)

    Whipple, F. L.

    1973-01-01

    Growing planetesimals and a range of drag laws depending on the Reynolds number and on the ratio of particle size to mean free path are considered. Particles spiral in the direction of positive gradient, thus being concentrated toward toroidal concentrations of gas. The effect increases with decreasing rates of particle growth, i.e., with increasing time scales of planet formation by accretion. In the outer regions, where evidence suggests that comets were formed and Uranus and Neptune were so accumulated, the effect of the pressure gradient is to clear the forming comets from those regions. The large mass of Neptune may have developed because of this effect, perhaps Neptune's solar distance was reduced from Bode's law, and perhaps no comet belt exists beyond Neptune. In the asteroid belt, on a slow time scale, the effect may have spiraled planetesimals toward Mars and Jupiter, thus contributing to the lack of planet formation in this region.

  12. Changes in lipids and lipoprotein particle concentrations after interruption of antiretroviral therapy

    DEFF Research Database (Denmark)

    Lampe, Fiona C; Duprez, Daniel A; Kuller, Lewis H;

    2010-01-01

    The effect of interruption of antiretroviral therapy (ART) on lipoprotein particle subclasses has not been studied. We examined short-term changes in lipids and lipoprotein particles among 332 HIV-infected individuals randomized to interrupt or continue ART in the "Strategies for Management of An...

  13. Local and seasonal variations in concentrations of chlorinated polycyclic aromatic hydrocarbons associated with particles in a Japanese megacity.

    Science.gov (United States)

    Ohura, Takeshi; Kamiya, Yuta; Ikemori, Fumikazu

    2016-07-15

    Concentrations of particle-bound polycyclic aromatic hydrocarbons (PAHs) and chlorinated PAHs (ClPAHs) were measured in different seasons at five sampling stations in Nagoya, a Japanese megacity. The annual mean total ClPAH and total PAH concentrations were 43.3-92.6pg/m(3) and 5200-8570pg/m(3), respectively. The concentrations of total ClPAHs were significantly variable than those of total PAHs, and both total concentrations through the seasons did not significantly correlate at any of the stations. Principal component analysis was used to characterize the ClPAH sources, resulted that ClPAHs were found to be associated with the sources of high-molecular-weight PAHs in the warmer seasons and of low-molecular-weight PAHs in the colder seasons. These findings suggest that principal sources of particle-bound ClPAHs are present in the local area, and change in the seasons. Toxic equivalent (TEQ) concentrations were estimated to assess the risks associated with exposure to ClPAHs in air. The TEQ concentrations in the samples were 0.05-0.32pg-TEQ/m(3). The TEQ concentrations in summer were approximately half the TEQ concentrations in the other seasons at all of the stations. PMID:27037480

  14. Continuous Measurement of Number Concentrations and Elemental Composition of Aerosol Particles for a Dust Storm Event in Beijing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A continuous measurement of number size distributions and chemical composition of aerosol particles was conducted in Beijing in a dust storm event during 21-26 March 2001. The number concentration of coarse particles (>2μm) increased more significantly than fine particles (<2μm) during the dust storm due to dust weather, while the anthropogenic aerosols collected during the non-dust-storm period tended to be associated with fine particles. Elemental compositions were analyzed by using proton-induced X-ray emission (PIXE). The results show that 20 elements in the dust storm were much higher than in the non-dust-storm period. The calculated soil dust concentration during the dust storm was, on average, 251.8μg m-3, while it was only 52.1 μg m-3 on non-dust-storm days. The enrichment factors for Mg, Al, P, K, Ca, Ti, Mn, Fe, Cl, Cu, Pb, and Zn show small variations between the dust storm and the non-dust-storm period, while those for Ca, Ni and Cr in the dust storm were much lower than those in the non-dust-storm period due to significant local emission sources. A high concentration and enrichment factor for S were observed during the dust storm, which implies that the dust particles were contaminated by aerosol particles from anthropogenic emissions during the long-range transport. A statistical analysis shows that the elemental composition of particles collected during the dust storm in Beijing were better correlated with those of desert soil colleted from desert regions in Inner Mongolia. Air mass back-trajectory analysis further confirmed that this dust storm event could be identified as streaks of dust plumes originating from Inner Mongolia.

  15. Variability of levels of PM, black carbon and particle number concentration in selected European cities

    Directory of Open Access Journals (Sweden)

    C. Reche

    2011-03-01

    Full Text Available In many large cities of Europe standard air quality limit values of particulate matter (PM are exceeded. Emissions from road traffic and biomass burning are frequently reported to be the major causes. As a consequence of these exceedances a large number of air quality plans, most of them focusing on traffic emissions reductions, have been implemented in the last decade. In spite of this implementation, a number of cities did not record a decrease of PM levels. Thus, is the efficiency of air quality plans overestimated? Or do we need a more specific metric to evaluate the impact of the above emissions on the levels of urban aerosols?

    This study shows the results of the interpretation of the 2009 variability of levels of PM, black carbon (BC, aerosol number concentration (N and a number of gaseous pollutants in seven selected urban areas covering road traffic, urban background, urban-industrial, and urban-shipping environments from southern, central and northern Europe.

    The results showed that variations of PM and N levels do not always reflect the variation of the impact of road traffic emissions on urban aerosols. However, BC levels vary proportionally with those of traffic related gaseous pollutants, such as CO, NO2 and NO. Due to this high correlation, one may suppose that monitoring the levels of these gaseous pollutants would be enough to extrapolate exposure to traffic-derived BC levels. However, the BC/CO, BC/NO2 and BC/NO ratios vary widely among the cities studied, as a function of distance to traffic emissions, vehicle fleet composition and the influence of other emission sources such as biomass burning. Thus, levels of BC should be measured at air quality monitoring sites.

    During traffic rush hours, a narrow variation in the N/BC ratio was evidenced, but a wide variation of this ratio was determined for the noon period. Although in central and northern Europe N and BC levels tend to vary

  16. Titanium Dioxide Particle Type and Concentration Influence the Inflammatory Response in Caco-2 Cells

    Directory of Open Access Journals (Sweden)

    Saeko Tada-Oikawa

    2016-04-01

    Full Text Available Titanium dioxide (TiO2 nanoparticles are widely used in cosmetics, sunscreens, biomedicine, and food products. When used as a food additive, TiO2 nanoparticles are used in significant amounts as white food-coloring agents. However, the effects of TiO2 nanoparticles on the gastrointestinal tract remain unclear. The present study was designed to determine the effects of five TiO2 particles of different crystal structures and sizes in human epithelial colorectal adenocarcinoma (Caco-2 cells and THP-1 monocyte-derived macrophages. Twenty-four-hour exposure to anatase (primary particle size: 50 and 100 nm and rutile (50 nm TiO2 particles reduced cellular viability in a dose-dependent manner in THP-1 macrophages, but in not Caco-2 cells. However, 72-h exposure of Caco-2 cells to anatase (50 nm TiO2 particles reduced cellular viability in a dose-dependent manner. The highest dose (50 µg/mL of anatase (100 nm, rutile (50 nm, and P25 TiO2 particles also reduced cellular viability in Caco-2 cells. The production of reactive oxygen species tended to increase in both types of cells, irrespective of the type of TiO2 particle. Exposure of THP-1 macrophages to 50 µg/mL of anatase (50 nm TiO2 particles increased interleukin (IL-1β expression level, and exposure of Caco-2 cells to 50 µg/mL of anatase (50 nm TiO2 particles also increased IL-8 expression. The results indicated that anatase TiO2 nanoparticles induced inflammatory responses compared with other TiO2 particles. Further studies are required to determine the in vivo relevance of these findings to avoid the hazards of ingested particles.

  17. Nature of crystalline particle assembly in ring shaped colloidal stains from concentrated dispersions

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Fenfen; Huynh, Trang [Laboratory for Optics and Applied Mechanics, Monash University, Clayton VIC 3800 (Australia); Somers, Anthony [Institute for Frontier Materials, Deakin University, 221 Burwood Highway, Burwood VIC 3125 Australia (Australia); Liu, Boyin; Fu, Jing [Department of Mechanical and Aerospace Engineering, Monash University, Clayton VIC 3800 (Australia); Muradoglu, Murat [Laboratory for Optics and Applied Mechanics, Monash University, Clayton VIC 3800 (Australia); Ng, Tuck Wah, E-mail: engngtw@gmail.com [Laboratory for Optics and Applied Mechanics, Monash University, Clayton VIC 3800 (Australia)

    2014-05-15

    The drying of colloidal droplet suspensions is important in many realms of practical application and has sustained the interest of researchers over two decades. The arrangements of polystyrene and silica beads, both of diameter 1 μm, 10% by volume of solid deposited on normal glass (hydrophilic), and silicone (hydrophobic) surfaces evaporated from a suspension volume of 3 μL, were investigated. Doughnut shape depositions were found, imputing the influence of strong central circulation flows that resulted in three general regions. In the central region which had strong particle build-up, the top most layers of particle arrangement was confirmed to be disordered using power spectrum and radial distribution function analysis. On closer examination, this appeared more like frustrated attempts to crystallize into larger grains rather than beads arranging in a disordered fashion throughout the piling process. With an adapted micro-bulldozing operation to progressively remove layers of particles from the heap, we found that the later efforts to crystallize through lateral capillary inter-particle forces were liable to be undone once the particles contacted the disorganized particles underneath, which were formed out of the jamming of fast particles arriving at the surface.

  18. Emulsion Polymerization of Etyl Acrylate: The Effect of Surfactant, Initiator Concentration and PolymerizationTechnique on Particle Size Distribution

    Directory of Open Access Journals (Sweden)

    Nitri Arinda

    2009-04-01

    Full Text Available Emulsion polymerization was conducted using ethyl acrylate monomer. Theeffect of sodium lauryl sulfate concentration, ammonium persulfate concentration, the various of polymerizationtechniques and feeding time to the conversion, particle size and its distribution were observed. The purpose of thisresearch is to obtain the optimum condition of ethyl acrylate homopolymer with particle size around 100 nm, to get theparticle size distribution monodisperse and to get solid content value of the experiment closed to its theoretical value.The optimum condition then could be applied in shell polymerization of core-shell polymers. The results of the researchshowed that semicontinuous technique obtained optimum sodium lauryl sulfate concentration at 20 CMC (criticalmicelle concentration and ammonium persulfate concentration is 3%. By using batch technique that the biggestparticle size is 123 nm with conversion 95.8% and monodisperse. The shorter of feeding time the more monomer ofethyl acrylate being polymerized, it is showed by the higher conversion up to 94.4% and the bigger particle size is107.9 nm.

  19. Zone of influence for particle number concentrations at signalised traffic intersections

    Science.gov (United States)

    Goel, Anju; Kumar, Prashant

    2015-12-01

    Estimation of zone of influences (ZoI) at signalised traffic intersections (TI) is important to accurately model particle number concentrations (PNCs) and their exposure to public at emission hotspot locations. However, estimates of ZoI for PNCs at different types of TIs are barely known. We carried out mobile measurements inside the car cabin with windows fully open for size-resolved PNCs in the 5-560 nm range on a 6 km long busy round route that had 10 TIs. These included four-way TIs without built-up area (TI4w-nb), four-way TIs with built-up area (TI4w-wb), three-way TIs without built-up area (TI3w-nb) and three-way TIs with built-up area (TI3w-wb). Mobile measurements were made with a fast response differential mobility spectrometer (DMS50). Driving speed and position of the car were recorded every second using a global positioning system (GPS). Positive matrix factorisation (PMF) modelling was applied on the data to quantify the contribution of PNCs released during deceleration, creep-idling, acceleration and cruising to total PNCs at the TIs. The objectives were to address the following questions: (i) how does ZoI vary at different types of TIs in stop- and go-driving conditions?, (ii) what is the effect of different driving conditions on ZoI of a TI?, (iii) how realistically can the PNC profiles be generalised within a ZoI of a TI?, and (iv) what is the share of emissions during different driving conditions towards the total PNCs at a TI? Average length of ZoI in longitudinal direction and along the road was found to be the highest (148 m; 89 to -59 m from the centre of a TI) at a TI3w-wb, followed by TI4w-nb (129 m; 79 to -42 m), TI3w-nb (86 m; 71 to -15 m) and TI4w-wb (79 m; 46 to -33 m) in stop- and go-driving conditions. During multiple stopping driving conditions when a vehicle stops at a TI more than once in a signal cycle due to oversaturation of vehicles, average length of ZoI increased by 55, 22 and 21% at TI4w-nb, TI3w-nb and TI3w-wb, respectively

  20. Method for relating suspended-chemical concentrations to suspended-sediment particle-size classes in storm-water runoff

    Science.gov (United States)

    Rinella, Joseph F.; McKenzie, Stuart W.

    1982-01-01

    A method has been developed to relate suspended-chemical concentrations (associated with suspended sediments) in storm-water runoff to suspended-sediment particle-size classes. These classes are based on settling velocities in quiescent native water. This method requires processing 20 liters of water having a suspended-sediment concentration greater than 500 milligrams per liter. However, samples with suspended-sediment concentrations as low as 250 milligrams per liter may be analyzed, if sample volumes are increased to 50 liters. The time required for one person to separate suspended sediments into particle-size classes ranges from 6 to 14 hours. This report outlines procedures for processing metal, nutrient, and organic samples.

  1. Influence of hydrogen concentration on Fe2O3 particle reduction in fluidized beds under constant drag force

    Institute of Scientific and Technical Information of China (English)

    Lei Guo; Han Gao; Jin-tao Yu; Zong-liang Zhang; Zhan-cheng Guo

    2015-01-01

    The fixed-gas drag force from a model calculation method that stabilizes the agitation capabilities of different gas ratios was used to explore the influence of temperature and hydrogen concentration on fluidizing duration, metallization ratio, utilization rate of reduction gas, and sticking behavior. Different hydrogen concentrations from 5vol%to 100vol%at 1073 and 1273 K were used while the drag force with the flow of N2 and H2 (N2:2 L·min−1;H2:2 L·min−1) at 1073 K was chosen as the standard drag force. The metallization ratio, mean reduc-tion rate, and utilization rate of reduction gas were observed to generally increase with increasing hydrogen concentration. Faster reduction rates and higher metallization ratios were obtained when the reduction temperature decreased from 1273 to 1073 K. A numerical relation among particle diameter, particle drag force, and fluidization state was plotted in a diagram by this model.

  2. Cardiopulmonary Toxicity Induced by Ambient Particulate Matter (BI City Concentrated Ambient Particle Study)

    Energy Technology Data Exchange (ETDEWEB)

    Annette Rohr; James Wagner Masako Morishita; Gerald Keeler; Jack Harkema

    2010-06-30

    Alterations in heart rate variability (HRV) have been reported in rodents exposed to concentrated ambient particles (CAPs) from different regions of the United States. The goal of this study was to compare alterations in cardiac function induced by CAPs in two distinct regional atmospheres. AirCARE 1, a mobile laboratory with an EPA/Harvard fine particle (particulate matter <2.5 {micro}m; PM{sub 2.5}) concentrator was located in urban Detroit, MI, where the PM mixture is heavily influenced by motor vehicles, and in Steubenville, OH, where PM is derived primarily from long-range transport and transformation of power plant emissions, as well as from local industrial operations. Each city was studied during both winter and summer months, for a total of four sampling periods. Spontaneously hypertensive rats instrumented for electrocardiogram (ECG) telemetry were exposed to CAPs 8 h/day for 13 consecutive days during each sampling period. Heart rate (HR), and indices of HRV (standard deviation of the average normal-to-normal intervals [SDNN]; square root of the mean squared difference of successive normal-to-normal intervals [rMSSD]), were calculated for 30-minute intervals during exposures. A large suite of PM components, including nitrate, sulfate, elemental and organic carbon, and trace elements, were monitored in CAPs and ambient air. In addition, a unique sampler, the Semi-Continuous Elements in Air Sampler (SEAS) was employed to obtain every-30-minute measurements of trace elements. Positive matrix factorization (PMF) methods were applied to estimate source contributions to PM{sub 2.5}. Mixed modeling techniques were employed to determine associations between pollutants/CAPs components and HR and HRV metrics. Mean CAPs concentrations in Detroit were 518 and 357 {micro}g/m{sup 3} (summer and winter, respectively) and 487 and 252 {micro}g/m{sup 3} in Steubenville. In Detroit, significant reductions in SDNN were observed in the summer in association with cement

  3. Cardiopulmonary Toxicity Induced by Ambient Particulate Matter (BI City Concentrated Ambient Particle Study)

    Energy Technology Data Exchange (ETDEWEB)

    Annette Rohr; James Wagner Masako Morishita; Gerald Keeler; Jack Harkema

    2010-06-30

    Alterations in heart rate variability (HRV) have been reported in rodents exposed to concentrated ambient particles (CAPs) from different regions of the United States. The goal of this study was to compare alterations in cardiac function induced by CAPs in two distinct regional atmospheres. AirCARE 1, a mobile laboratory with an EPA/Harvard fine particle (particulate matter <2.5 {micro}m; PM{sub 2.5}) concentrator was located in urban Detroit, MI, where the PM mixture is heavily influenced by motor vehicles, and in Steubenville, OH, where PM is derived primarily from long-range transport and transformation of power plant emissions, as well as from local industrial operations. Each city was studied during both winter and summer months, for a total of four sampling periods. Spontaneously hypertensive rats instrumented for electrocardiogram (ECG) telemetry were exposed to CAPs 8 h/day for 13 consecutive days during each sampling period. Heart rate (HR), and indices of HRV (standard deviation of the average normal-to-normal intervals [SDNN]; square root of the mean squared difference of successive normal-to-normal intervals [rMSSD]), were calculated for 30-minute intervals during exposures. A large suite of PM components, including nitrate, sulfate, elemental and organic carbon, and trace elements, were monitored in CAPs and ambient air. In addition, a unique sampler, the Semi-Continuous Elements in Air Sampler (SEAS) was employed to obtain every-30-minute measurements of trace elements. Positive matrix factorization (PMF) methods were applied to estimate source contributions to PM{sub 2.5}. Mixed modeling techniques were employed to determine associations between pollutants/CAPs components and HR and HRV metrics. Mean CAPs concentrations in Detroit were 518 and 357 {micro}g/m{sup 3} (summer and winter, respectively) and 487 and 252 {micro}g/m{sup 3} in Steubenville. In Detroit, significant reductions in SDNN were observed in the summer in association with cement

  4. Environmental geochemistry of shale-hosted Ag-Pb-Zn massive sulfide deposits in northwest Alaska: Natural background concentrations of metals in water from mineralized areas

    Science.gov (United States)

    Kelley, K.D.; Taylor, C.D.

    1997-01-01

    Red Dog, Lik and Drenchwater are shale-hosted stratiform Ag-Pb-Zn massive sulfide deposits in the northwestern Brooks Range. Natural background concentrations of metals in waters from the undisturbed (unmined) Drenchwater prospect and Lik deposit were compared to pre-mining baseline studies conducted at Red Dog. The primary factors affecting water chemistry are the extent of exposure of the deposits, the grade of mineralization, the presence of carbonate reeks in the section, and the proportion of Fe-sulfide in the ore. Surface water samples from the Drenchwater prospect, which has pyrite-dominant mineralization exposed in outcrop, have pH values as low as 2.8 and high dissolved concentrations of metals including as much as 95 mg 1-1 Al, 270 mg 1-1 Fe, 8 ??1-1 Cd, 10 ??1-1 Pb, and 2600 ??1-1 Zn, with As up to 26 ??g1-1. Surface waters from the Red Dog deposit prior to mining were also acidic and metal-rich, however, dissolved metal concentrations in Red Dog waters were many times greater. The higher metal concentrations in Red Dog waters reflect the high Zn grades and the abundant sphalerite, pyrite, and galena that were present in outcrop prior to mining. In contrast, despite significant mineralization at the Lik deposit, carbonate rocks in the section buffer the system, resulting in less acidic, mostly near-neutral pH values with low concentrations of most metals except Zn.

  5. Magnetic nanoparticle hyperthermia cancer treatment efficacy dependence on cellular and tissue level particle concentration and particle heating properties

    Science.gov (United States)

    Petryk, Alicia A.; Misra, Adwiteeya; Mazur, Courtney M.; Petryk, James D.; Hoopes, P. J.

    2015-03-01

    The use of nanotechnology for the treatment of cancer affords the possibility of highly specific tumor targeting and improved treatment efficacy. Iron oxide magnetic nanoparticles (IONPs) have demonstrated success as an ablative mono-therapy and targetable adjuvant therapy. However, the relative therapeutic value of intracellular vs. extracellular IONPs remains unclear. Our research demonstrates that both extracellular and intracellular IONPs generate cytotoxicity when excited by an alternating magnetic field (AMF). While killing individual cells via intracellular IONP heating is an attractive goal, theoretical models and experimental results suggest that this may not be possible due to limitations of cell volume, applied AMF, IONP concentration and specific absorption rate (SAR). The goal of this study was to examine the importance of tumor size (cell number) with respect to IONP concentration. Mouse mammary adenocarcinoma cells were incubated with IONPs, washed, spun into different pellet sizes (0.1, 0.5 and 2 million cells) and exposed to AMF. The level of heating and associated cytotoxicity depended primarily on the number of IONPs /amount Fe per cell pellet volume and the relative volume of the cell pellet. Specifically, larger cell pellets achieved greater relative cytotoxicity due to greater iron amounts, close association and subsequently higher temperatures.

  6. Investigations into the penetration and pressure drop of HEPA filter media during loading with submicron particle aerosols at high concentrations

    International Nuclear Information System (INIS)

    High Efficiency Particulate Air (HEPA) filters are typically employed in particle removal and retention within the air cleaning systems of clean rooms in the pharmaceutical, nuclear and semiconductor industries for dust concentrations of some μg/m3. Their extremely high removal efficiencies for submicron particles make them attractive candidates in complying with increasingly lower emission limits for industrial processes that involve dust concentrations of up to several g/m3. Cost-effective operation under such conditions requires the filter units to be recleanable. The recleanability of HEPA filter media depends not only on the operating conditions during the cleaning process but also on the filtration conditions during particle loading. The structure and location of the particles captured by the glass fiber matrix greatly affect the degree to which they can be subsequently dislodged and removed from the filter medium. Changes in filtration efficiency with service time for various particle diameters in the critical submicron size range, as well as the effects of filtration velocity on the increase in pressure drop, are important criteria with regard to recleaning HEPA filter units. Of special significance for the recleanability of HEPA filter media is knowledge of how operating conditions affect dust cake formation. (author)

  7. Protoplanetary Disk Turbulence Driven by the Streaming Instability: Non-Linear Saturation and Particle Concentration

    CERN Document Server

    Johansen, A; Johansen, Anders; Youdin, Andrew

    2007-01-01

    We present simulations of the non-linear evolution of streaming instabilities in protoplanetary disks. The two components of the disk, gas treated with grid hydrodynamics and solids treated as superparticles, are mutually coupled by drag forces. We find that the initially laminar equilibrium flow spontaneously develops into turbulence in our unstratified local model. Marginally coupled solids (that couple to the gas on a Keplerian time-scale) trigger an upward cascade to large particle clumps with peak overdensities above 100. The clumps evolve dynamically by losing material downstream to the radial drift flow while receiving recycled material from upstream. Smaller, more tightly coupled solids produce weaker turbulence with more transient overdensities on smaller length scales. The net inward radial drift is decreased for marginally coupled particles, whereas the tightly coupled particles migrate faster in the saturated turbulent state. The turbulent diffusion of solid particles, measured by their random wal...

  8. Cardiovascular Effects in Adults with Metabolic Syndrome Exposed to Concentrated Ultrafine Air Pollution Particles

    Science.gov (United States)

    RATIONALE: Epidemiologic studies report associations between ambient air pollution particulate matter (PM) and various indices of cardiopulmonary morbidity and mortality. A leading hypothesis contends that smaller ultrafine (UF) particles induce a greater physiologic response bec...

  9. Features of the gas discharge in the narrow gap micro-pattern gas detectors (MPGD) at a high level of alpha-particles background

    CERN Document Server

    Razin, V I

    2010-01-01

    In given article preliminary results of the research of the electron multiplication in MPGD are presented at a high level of alpha-particles background. This work has expanded borders of understanding of the streamer mode nature. It is seen as a complex from electrostatic and electromagnetic interactions which begin with appearance of the precursor in plasma state. In an inter-electrode gap the plasma oscillations occur, accompanied by longitudinal elastic waves of ionization, which can reach the cathode surface with induced negative charge. With the release of this charge due to previously established conducting channel there is a strong current pulse, accompanied by the emission due to recombination of positive and negative ions and a thin cord or streamer derive. In the aim of the MPGD protection from the spark breakdown at a high level of the alpha-particle background the next gas composition from a buffer, cooling and electronegative components are offered: 70% He +28% CF4 +2% SF6.

  10. Effect of Aerogel Particle Concentration on Mechanical Behavior of Impregnated RTV 655 Compound Material for Aerospace Applications

    Directory of Open Access Journals (Sweden)

    Firouzeh Sabri

    2014-01-01

    Full Text Available Aerogels are a unique class of materials with superior thermal and mechanical properties particularly suitable for insulating and cryogenic storage applications. It is possible to overcome geometrical restrictions imposed by the rigidity of monolithic polyurea cross-linked silica aerogels by encapsulating micrometer-sized particles in a chemically resistant thermally insulating elastomeric “sleeve.” The ultimate limiting factor for the compound material’s performance is the effect of aerogel particles on the mechanical behavior of the compound material which needs to be fully characterized. The effect of size and concentration of aerogel microparticles on the tensile behavior of aerogel impregnated RTV655 samples was explored both at room temperature and at 77 K. Aerogel microparticles were created using a step-pulse pulverizing technique resulting in particle diameters between 425 μm and 90 μm and subsequently embedded in an RTV 655 elastomeric matrix. Aerogel particle concentrations of 25, 50, and 75 wt% were subjected to tensile tests and behavior of the compound material was investigated. Room temperature and cryogenic temperature studies revealed a compound material with rupture load values dependent on (1 microparticle size and (2 microparticle concentration. Results presented show how the stress elongation behavior depends on each parameter.

  11. Short-term exposure with high concentrations of pristine microplastic particles leads to immobilisation of Daphnia magna.

    Science.gov (United States)

    Rehse, Saskia; Kloas, Werner; Zarfl, Christiane

    2016-06-01

    Recent studies revealed that freshwaters are not only polluted by chemicals, but also by persistent synthetic material like microplastics (plastic particles Microplastics include a diverse range of characteristics, e.g. polymer type, size or shape, but also their tendency to sorb pollutants or release additives. Although there is rising concern about the pollution of freshwaters by microplastics, knowledge about their potential effects on organisms is limited. For a better understanding of their risks, it is crucial to unravel which characteristics influence their effects on organisms. Analysing effects by the mere particles is the first step before including more complex interactions e.g. with associated chemicals. The aim of this study was to analyse potential physical effects of microplastics on one representative organism for limnic zooplankton (Daphnia magna). We investigated whether microplastics can be ingested and whether their presence causes adverse effects after short-term exposure. Daphnids were exposed for up to 96 h to 1-μm and 100-μm polyethylene particles at concentrations between 12.5 and 400 mg L(-1). Ingestion of 1-μm particles led to immobilisation increasing with dose and time with an EC50 of 57.43 mg L(-1) after 96 h. 100-μm particles that could not be ingested by the daphnids had no observable effects. These results underline that, considering high concentrations, microplastic particles can already induce adverse effects in limnic zooplankton. Although it needs to be clarified if these concentrations can be found in the environment these results are a basis for future impact analysis, especially in combination with associated chemicals. PMID:27010171

  12. Rapid calculation of hydrodynamic and transport properties in concentrated solutions of colloidal particles and macromolecules

    Science.gov (United States)

    Swan, James W.; Wang, Gang

    2016-01-01

    A new method for calculating the resistance tensors of arbitrarily shaped particles and the translational and rotational self-diffusivity in suspensions of such particles is developed. This approach can be harnessed to efficiently and accurately predict the hydrodynamic and transport properties of large macromolecules such as antibodies in solution. Particles are modeled as a rigid composite of spherical beads, and the continuum equations for low Reynolds number fluid mechanics are used to calculate the drag on the composite or its diffusivity in a solution of other composites. The hydrodynamic calculations are driven by a graphics processing unit (GPU) implementation of the particle-mesh-Ewald technique which offers log-linear scaling with respect to the complexity of the composite-bead particles modeled as well as high speed execution leveraging the hyper-parallelization of the GPU. Matrix-free expressions for the hydrodynamic resistance and translational and rotational diffusivity of composite bead particles are developed, which exhibit substantial improvements in computational complexity over existing approaches. The effectiveness of these methods is demonstrated through a series of calculations for composite-bead particles having a spherical geometry, and the results are compared to exact solutions for spheres. Included in the supplementary material is an implementation of the proposed algorithm which functions as a plug-in for the GPU molecular dynamics suite HOOMD-blue (http://codeblue.umich.edu/hoomd-blue) [J. A. Anderson, C. D. Lorenz, and A. Travesset, "General purpose molecular dynamics simulations fully implemented on graphics processing units," J. Comput. Phys. 227(10), 5342-5359 (2008) and Glaser et al., "Strong scaling of general-purpose molecular dynamics simulations on GPUs," Comput. Phys. Commun. 192, 97-107 (2015)].

  13. Diel variations of marine snow concentration in surface waters and implications for particle flux in the sea

    Science.gov (United States)

    Graham, William M.; MacIntyre, Sally; Alldredge, Alice L.

    2000-03-01

    Successive measurements of the size distribution and abundance of marine snow in the upper 100 m of the Santa Barbara Channel, California, with an in situ still camera system following 11 tagged water masses revealed a consistent pattern of nighttime decreases in the abundance of large particles. A net nocturnal reduction in particulate flux from the upper 100 m as calculated from camera profiles occurred in 75% of the day-night comparisons, and nighttime aggregate carbon losses resulted in a 38% average reduction in camera-derived aggregate flux. Intensive investigation of three stations for 24-48 h each indicated that nighttime decreases in aggregate concentrations and derived aggregate flux could be registered throughout the observed water column. Nocturnal decreases in marine snow concentration are unlikely to result from diel variations in the production of marine snow either as feeding webs of zooplankton or through variations in aggregation rates of smaller particles. Moreover, measured diel variations in the intensity of surface mixing and convective overturn during one of the 24 h deployments were not intense enough to produce aggregate fragmentation and reduced aggregate flux. Nighttime increases in large crustacean zooplankton (i.e., euphausiids and the large copepod Calanus pacificus) could explain some or all of the reduction in aggregate abundance at most stations. Fragmentation and consumption of marine snow by migrating macrozooplankton could produce our observed synchronous diel cycles in marine snow concentration. This is the first empirical evidence of a diel pattern in the concentration and calculated particulate flux of large sinking particles in near-surface waters. The data presented here are consistent with the only other existing diel study, which also reported decreases in marine snow abundance at night at 270 m depths in the oceanic north Atlantic. Diel variations in the sizes and concentrations of marine snow may impact water column

  14. Characterization of concentration, particle size distribution, and contributing factors to ambient hexavalent chromium in an area with multiple emission sources

    Science.gov (United States)

    Yu, Chang Ho; Huang, Lihui; Shin, Jin Young; Artigas, Francisco; Fan, Zhi-hua (Tina)

    2014-09-01

    Airborne hexavalent chromium (Cr(VI)) is a known pulmonary carcinogen and can be emitted from both natural and anthropogenic sources, including diesel emissions. However, there is limited knowledge about ambient Cr(VI) concentration levels and its particle size distribution. This pilot study characterized ambient Cr(VI) concentrations in the New Jersey Meadowlands (NJ ML) district, which is close to the heavily trafficked New Jersey Turnpike (NJTPK) as well as Chromium Ore Processing Residue (COPR) waste sites. Monitoring was simultaneously conducted at two sites, William site (∼50 m from NJTPK) and MERI site (∼700 m from NJTPK). The distance between the two sites is approximately 6.2 km. Ambient Cr(VI) concentrations and PM2.5 mass concentrations were concurrently measured at both sites during summer and winter. The summer concentrations (mean ± S.D. [median]), 0.13 ± 0.06 [0.12] ng/m3 at the MERI site and 0.08 ± 0.05 [0.07] ng/m3 at the William site, were all significantly higher than the winter concentrations, 0.02 ± 0.01 [0.02] ng/m3 and 0.03 ± 0.01 [0.03] ng/m3 at the MERI and William sites, respectively. The site difference (i.e., MERI > William) was observed for summer Cr(VI) concentrations; however, no differences for winter and pooled datasets. These results suggest higher Cr(VI) concentrations may be attributed from stronger atmospheric reactions such as photo-oxidation of Cr(III) to Cr(VI) in the summer. The Cr(VI) distribution as a function of particle size, ranging from 0.18 to 18 μm, was determined at the William site. It was found that Cr(VI) was enriched in the particles less than 2.5 μm in diameter (PM2.5). This finding suggested potential health concerns, because PM2.5 are easily inhaled and deposited in the alveoli. A multiple linear regression analysis confirmed ambient Cr(VI) concentrations were significantly affected by meteorological factors (i.e., temperature and humidity) and reactive gases/particles (i.e., O3, Fe and Mn).

  15. Time-Evolution of a Fractal Distribution: Particle Concentrations in Free-Surface Turbulence

    CERN Document Server

    Larkin, Jason; Bandi, M M

    2010-01-01

    Steady-state turbulence is generated in a tank of water and the trajectories of particles forming a compressible system on the surface are tracked in time. The initial uniformly distributed floating particles coagulate and form a fractal distribution, a rare manifestation of a fractal object observable in real-space. The surface pattern reaches a steady state in approximately 1 s. Measurements are made of the fractal dimensions $D_q(t)$ ($q=1$ to $6$) of the floating particles starting with the uniform distribution $D_q(0)$ = 2 for Taylor Microscale Reynolds number $Re_{\\lambda} \\simeq 160$. Focus is on the the time-evolution of the correlation dimension $D_2(t)$ as the steady state is approached. This steady state is reached in several large eddy turnover times and does so at an exponential rate.

  16. Improved concentration and separation of particles in a 3D dielectrophoretic chip integrating focusing, aligning and trapping

    KAUST Repository

    Li, Ming

    2012-10-18

    This article presents a dielectrophoresis (DEP)-based microfluidic device with the three-dimensional (3D) microelectrode configuration for concentrating and separating particles in a continuous throughflow. The 3D electrode structure, where microelectrode array are patterned on both the top and bottom surfaces of the microchannel, is composed of three units: focusing, aligning and trapping. As particles flowing through the microfluidic channel, they are firstly focused and aligned by the funnel-shaped and parallel electrode array, respectively, before being captured at the trapping unit due to negative DEP force. For a mixture of two particle populations of different sizes or dielectric properties, with a careful selection of suspending medium and applied field, the population exhibits stronger negative DEP manipulated by the microelectrode array and, therefore, separated from the other population which is easily carried away toward the outlet due to hydrodynamic force. The functionality of the proposed microdevice was verified by concentrating different-sized polystyrene (PS) microparticles and yeast cells dynamically flowing in the microchannel. Moreover, separation based on size and dielectric properties was achieved by sorting PS microparticles, and isolating 5 μm PS particles from yeast cells, respectively. The performance of the proposed micro-concentrator and separator was also studied, including the threshold voltage at which particles begin to be trapped, variation of cell-trapping efficiency with respect to the applied voltage and flow rate, and the efficiency of separation experiments. The proposed microdevice has various advantages, including multi-functionality, improved manipulation efficiency and throughput, easy fabrication and operation, etc., which shows a great potential for biological, chemical and medical applications. © 2012 Springer-Verlag Berlin Heidelberg.

  17. Dependence of the degree of antibacterial and antiphage action of ozone on cell and phage particle concentrations in nutrient media

    Energy Technology Data Exchange (ETDEWEB)

    Grits, N.V.; Fomichev, A.Iu.

    1985-05-01

    The work was aimed at studying the inactivating effect of ozone on Escherichia coli K-12 AB1157, Pseudomonas aeruginosa PA01, Erwinia herbicola EH103 and their phages T4, SM and I4. The degree of bacterial and phage inactivation was found to increase with a decrease in their initial concentration during the treatment. The effect depends on differences in the quantity of ozone per cell or per phage particle in the reaction medium. This conclusion is based on the fact that, irrespective of the suspension density, the amount of surviving bacteria and phages plotted versus O3 concentration and recalculated per one bacterial cell or phage particle is described graphically by one and the same curve typical of a strain under study. This technique for assessing the sensitivity of microbiological objects to ozone can be used in order to compare experimental data obtained in different laboratories.

  18. Effects of oxygen concentration on the characteristics of oxide particles in ODS steels

    International Nuclear Information System (INIS)

    Oxide dispersion strengthened (ODS) steel is being considered as a candidate structural material in future nuclear fission and fusion reactor systems mainly due to its excellent creep resistance and irradiation resistance at high temperatures. ODS steel normally contains an exceptionally high oxygen concentration owing to the elemental powders themselves, as well as to the contamination during mechanical alloying (MA) and consolidation. It has been reported that excess oxygen concentration affects the mechanical properties of ODS steel. However, little attention has been paid to the effect of oxygen concentration on the characteristics of oxide precipitates. This study focuses on the effects of oxygen concentration on the characteristics of oxide precipitates in ODS steel

  19. Characterization of the inter-annual, seasonal, and diurnal variations of condensation particle concentrations at Neumayer, Antarctica

    OpenAIRE

    Weller, R; A. Minikin; Wagenbach, D.; Dreiling, V.

    2011-01-01

    Continuous condensation particle (CP) observations were conducted from 1984 through 2009 at Neumayer Station under stringent contamination control. During this period, the CP concentration (median 258 cm−3) showed no significant long term trend but exhibited a pronounced seasonality characterized by a stepwise increase starting in September and reaching its annual maximum of around 103 cm−3 in March. Minimum values below 10&...

  20. Vascular Effects of a Subchronic Inhalation Exposure to Concentrated Ambient Air Particles in Atherosclerosis Susceptible Mice

    Science.gov (United States)

    Numerous studies have reported the adverse effects of particulate air pollution on cardiovascular function and disease. The causal physiochemical properties of particles and their mechanisms of action/injury remain unknown. This study examined the vascular effects in 15 wk old ma...

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

    Science.gov (United States)

    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.

  2. Influence of the Polyvinyl Pyrrolidone Concentration on Particle Size and Dispersion of ZnS Nanoparticles Synthesized by Microwave Irradiation

    Directory of Open Access Journals (Sweden)

    Nayereh Soltani

    2012-09-01

    Full Text Available Zinc sulfide semiconductor nanoparticles were synthesized in an aqueous solution of polyvinyl pyrrolidone via a simple microwave irradiation method. The effect of the polymer concentration and the type of sulfur source on the particle size and dispersion of the final ZnS nanoparticle product was carefully examined. Microwave heating generally occurs by two main mechanisms: dipolar polarization of water and ionic conduction of precursors. The introduction of the polymer affects the heating rate by restriction of the rotational motion of dipole molecules and immobilization of ions. Consequently, our results show that the presence of the polymer strongly affects the nucleation and growth rates of the ZnS nanoparticles and therefore determines the average particle size and the dispersion. Moreover, we found that PVP adsorbed on the surface of the ZnS nanoparticles by interaction of the C–N and C=O with the nanoparticle’s surface, thereby affording protection from agglomeration by steric hindrance. Generally, with increasing PVP concentration, mono-dispersed colloidal solutions were obtained and at the optimal PVP concentration (5%, sufficiently small size and narrow size distributions were obtained from both sodium sulfide and thioacetamide sulfur sources. Finally, the sulfur source directly influences the reaction mechanism and the final particle morphology, as well as the average size.

  3. Spin 1/2 particle in the field of the Dirac string on the background of de Sitter space-time

    CERN Document Server

    Red'kov, V M; Veko, O V

    2011-01-01

    The Dirac monopole string is specified for de Sitter cosmological model. Dirac equation for spin 1/2 particle in presence of this monopole has been examined on the background of de Sitter space-time in static coordinates. Instead of spinor monopole harmonics, the technique of Wigner D-functions is used. After separation of the variables, detailed analysis of the radial equations is performed; four types of solutions, singular, regular, in- and out- running waves, are constructed in terms of hypergeometric functions. The complete set of spinor wave solutions \\Psi_{\\epsilon, j,m, \\lambda}(t,r, \\theta, \\phi) has been constructed, special attention is given to treating the states of minimal values of the total angular moment j_{\\min}.

  4. Biological Effects of Osteoblast-Like Cells on Nanohydroxyapatite Particles at a Low Concentration Range

    OpenAIRE

    Xiaochen Liu; Jie Wei; Shicheng Wei

    2011-01-01

    The biological effects of osteoblast-like MG-63 cells on nanohydroxyapatite (n-HA) at the low concentration range (5–25  g/mL) for 5 days was investigated. The results showed the viability and actin cytoskeleton of the cells descended with the increase of the concentration of n-HA, and the actin cytoskeleton of cells was depolymerised and became more disordered. Apoptotic rate of cells (1.85%, 1.99%, and 2.29%) increased with the increase of n-HA concentration (5, 15, and 25  g/mL) and be...

  5. Light concentration in the near-field of dielectric spheroidal particles with mesoscopic sizes

    Science.gov (United States)

    Mendes, Manuel J.; Tobías, Ignacio; Martí, Antonio; Luque, Antonio

    2011-08-01

    This paper presents a numerical study of the light focusing properties of dielectric spheroids with sizes comparable to the illuminating wavelength. An analytical separation-of-variables method is used to determine the electric field distribution inside and in the near-field outside the particles. An optimization algorithm was implemented in the method to determine the particles' physical parameters that maximize the forward scattered light in the near-field region. It is found that such scatterers can exhibit pronounced electric intensity enhancement (above 100 times the incident intensity) in their close vicinity, or along wide focal regions extending to 10 times the wavelength. The results reveal the potential of wavelength-sized spheroids to manipulate light beyond the limitations of macroscopic geometrical optics. This can be of interest for several applications, such as light management in photovoltaics.

  6. Sample preparation for measurement of plasma mycophenolic acid concentrations using chromatographically functionalized magnetic micro-particles.

    Science.gov (United States)

    König, Katrin; Vogeser, Michael

    2012-01-01

    Utilizing chromatographically modified magnetic micro-particles is an innovative principle of sample preparation for quantitative analysis of small molecules in complex biomedical samples by liquid chromatography tandem mass spectrometry. Since no vacuum or pressure has to be applied-in contrast to cartridge based solid phase extraction protocols-the principle's main characteristics are potentially straightforward automation and a high extraction performance (in terms of µg of extraction material per µL of sample). Following first descriptions of the approach, this article reports, the validation of a magnetic particle-based, analytical method for the quantification of the immunosuppressant mycophenolic acid in plasma. This sample preparation technology has shown a good performance for this clinically relevant analyte. As a result, we conclude that further work towards the implementation of this technology in a multi- analyte approach on robotic systems, aiming towards a fully automated process, is justified. PMID:23221116

  7. High concentrations of sub-3 nm clusters and frequent new particle formation observed in the Po Valley, Italy, during the PEGASOS 2012 campaign

    Directory of Open Access Journals (Sweden)

    J. Kontkanen

    2015-11-01

    Full Text Available The concentrations of neutral and charged sub-3 nm clusters and their connection to new particle formation (NPF were investigated during the PEGASOS campaign (7 June–9 July 2012 at the San Pietro Capofiume measurement station in the Po Valley, Italy. Continuous high concentrations of sub-3 nm clusters were detected during the measurement period, although the condensation sink was relatively high (median value 1.1 × 10-2 s-1. The median cluster concentrations were 2140 and 7980 cm-3 in the size bins of 1.5–1.8 nm and 1.8–3 nm, and the majority of them were electrically neutral. NPF events were observed during the measurement period frequently, on 86 % of the days. The median growth rates of clusters during the events were 4.3, 6.0 and 7.2 nm h-1 in the size ranges of 1.5–3, 3–7 and 7–20 nm. The median formation rate of 1.6 nm clusters was high, 45 cm-3 s-1, and it exceeded the median formation rate of 2 nm clusters by one order of magnitude. The ion-induced nucleation fraction was low; the median values were 0.7 % at 1.6 nm and 3.0 % at 2 nm. On NPF event days the neutral cluster concentration had a maximum around 9 a.m. (local winter time, which was absent on a non-event day. The increase in the cluster concentrations in the morning coincided with the increase in the boundary layer height. At the same time radiation and temperature increased and RH and condensation sink decreased. The concentration of neutral clusters was observed to have apositive correlation with sulfuric acid proxy, indicating the significance of sulfuric acid for the cluster formation in San Pietro Capofiume. The condensation sink had anegative correlation with the concentration of charged clusters but no clear relation to the neutral cluster concentration. This finding, together with back-trajectory analysis, suggests that the precursor vapors of the clusters and background aerosol particles, acting as their sink, have possibly originated from the same sources

  8. Monitoring sand particle concentration in multiphase flow using acoustic emission technology

    OpenAIRE

    El-Alej, Mohamed Essid

    2014-01-01

    Multiphase flow is the simultaneous flow of two or several phases through a system such as a pipe. This common phenomenon can be found in the petroleum and chemical engineering industrial fields. Transport of sand particles in multiphase production has attracted considerable attention given sand production is a common problem especially to the oil and gas industry. The sand production causes loss of pipe wall thickness which can lead to expensive failures and loss of product...

  9. Influence of the ambient humidity on the concentration of natural deposition-mode ice-nucleating particles

    Science.gov (United States)

    López, M. L.; Ávila, E. E.

    2016-01-01

    This study reports measurements of deposition-mode ice-nucleating particle (INP) concentrations at ground level during the period July-December 2014 in Córdoba, Argentina. Ambient air was sampled into a cloud chamber where the INP concentration was measured at a temperature of -25 °C and a 15 % supersaturation over ice. Measurements were performed on days with different thermodynamic conditions, including rainy days. The effect of the relative humidity at ground level (RHamb) on the INP concentration was analyzed. The number of INPs activated varied from 1 L-1 at RHamb of 25 % to 30 L-1 at RHamb of 90 %. In general, a linear trend between the INP concentration and the RHamb was found, suggesting that this variability must be related to the effectiveness of the aerosols acting as INPs. From the backward trajectories analysis, it was found that the link between INP concentration and RHamb is independent of the origin of the air masses. The role of biological INPs and nucleation occurring in pores and cavities was discussed as a possible mechanism to explain the increase of the INP concentration during high ambient relative humidity events. This work provides valuable measurements of deposition-mode INP concentrations from the Southern Hemisphere where INP data are sparse so far.

  10. Associations Between Ultrafine Particles and Co-Pollutant Concentrations in the Tampa Bay Area.

    Science.gov (United States)

    Desai, Ushang; Watson, Alain

    2016-05-01

    Ultrafine particles (UFPs) are ubiquitous in urban air and have been recognized as a risk to human health. The aim of this study was to measure the relationships among ultrafine particles and other ambient air pollutants and meteorological factors in the Tampa Bay Area. This study measured continuous UFPs, black carbon, oxides of nitrogen (NO(x)), nitrogen dioxide (NO2), nitric oxide (NO), carbon monoxide (CO), ozone (O3), sulfur dioxide (SO2), particulate matter having an aerodynamic diameter of 10 microns or less (PM10), relative humidity, wind speed, and ambient temperature during January to March 2014. Moreover, the study compared the relationship between UFPs and various co-pollutants daily, including during morning rush hour periods. This study found a moderate correlation among UFPs and black carbon, NO(x), NO2, and NO during hourly continuous measurements and rush hour periods, and a low level of correlation among UFPs and CO, O3, SO2, PM10, relative humidity, wind speed, and ambient temperature. This study indicates that co-pollutants should not be used as a surrogate to assess the human health risk from ultrafine particles exposure. PMID:27263179

  11. Particle Concentration At Planet Induced Gap Edges and Vortices: I. Inviscid 3-D Hydro Disks

    CERN Document Server

    Zhu, Zhaohuan; Rafikov, Roman R; Bai, Xuening

    2013-01-01

    We perform a systematic study of the dynamics of dust particles in protoplanetary disks with embedded planets using global 2-D and 3-D inviscid hydrodynamic simulations. We implement Lagrangian particles into magnetohydrodynamic code Athena with cylindrical coordinates and explore the behavior of dust grains with sizes spanning more than 6 orders of magnitude --- from the well-coupled to decoupled limits. We find two distinct outcomes depending on the mass of the embedded planet, which is varied between 8 M_earth to 9 M_{J}. In the presence of a low mass planet (8 M_earth), two narrow gaps start to open in the gas on each side of the planet where the density waves shock. Although these gaps are quite shallow, they dramatically affect particle drift speed and cause significant, axisymmetric dust depletion near the planet. On the other hand, a more massive planet (>0.1 M_{J}) carves out a deeper gap with sharp edges, which are unstable to the formation of vortices that later merge into a single vortex. The vort...

  12. Biological Effects of Osteoblast-Like Cells on Nanohydroxyapatite Particles at a Low Concentration Range

    Directory of Open Access Journals (Sweden)

    Xiaochen Liu

    2011-01-01

    Full Text Available The biological effects of osteoblast-like MG-63 cells on nanohydroxyapatite (n-HA at the low concentration range (5–25 g/mL for 5 days was investigated. The results showed the viability and actin cytoskeleton of the cells descended with the increase of the concentration of n-HA, and the actin cytoskeleton of cells was depolymerised and became more disordered. Apoptotic rate of cells (1.85%, 1.99%, and 2.29% increased with the increase of n-HA concentration (5, 15, and 25 g/mL and become significantly higher than the control. Total intracellular protein content decreased with n-HA concentration increase, showing significant difference between 25 g/mL and the control, and no significant change of ALP activity was observed at the 5th day. The results revealed that the cell growth was inhibited by n-HA in a concentration-dependent manner, and the obvious biological effects of MG-63 cells on n-HA existed at the low concentration range from 5 to 25 g/mL.

  13. Dietary forage concentration and particle size affect sorting, feeding behaviour, intake and growth of Chinese Holstein male calves.

    Science.gov (United States)

    Muhammad, A U R; Xia, C Q; Cao, B H

    2016-04-01

    The objective of study was to evaluate the effect of forage concentration (F:C) and forage particle length (FPL) on sorting, feeding behaviour, intake, growth and body measurements of growing calves. Twenty-eight weaned calves of body weight 156.79 ± 33.44 (mean ± SD) were used in 2 × 2 factorial arrangements with the factors FPL of hay grass (full and short) and hay grass concentrations (low, 50% and high, 65%). The treatments were as follows: full length (FL) with low F:C (50:50), FL with high F:C(65:35), short length (SL) with low F:C (50:50) and SL with high F:C (65:35). Increasing F:C and decreasing FPL enhanced sorting for short and fine particle and sorting against long particle (p behaviour, interaction for eating time and eating time per kilogram DM was present. Increasing the F:C increased the eating time in both FL and SL (p behaviour (p behaviour.

  14. Turbulent Concentration of MM-Size Particles in the Protoplanetary Nebula: Scaled-Dependent Multiplier Functions

    Science.gov (United States)

    Cuzzi, Jeffrey N.; Hartlep, Thomas; Weston, B.; Estremera, Shariff Kareem

    2014-01-01

    The initial accretion of primitive bodies (asteroids and TNOs) from freely-floating nebula particles remains problematic. Here we focus on the asteroids where constituent particle (read "chondrule") sizes are observationally known; similar arguments will hold for TNOs, but the constituent particles in those regions will be smaller, or will be fluffy aggregates, and are unobserved. Traditional growth-bysticking models encounter a formidable "meter-size barrier" [1] (or even a mm-cm-size barrier [2]) in turbulent nebulae, while nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids [3]. Even if growth by sticking could somehow breach the meter size barrier, other obstacles are encountered through the 1-10km size range [4]. Another clue regarding planetesimal formation is an apparent 100km diameter peak in the pre-depletion, pre-erosion mass distribution of asteroids [5]; scenarios leading directly from independent nebula particulates to this size, which avoid the problematic m-km size range, could be called "leapfrog" scenarios [6-8]. The leapfrog scenario we have studied in detail involves formation of dense clumps of aerodynamically selected, typically mm-size particles in turbulence, which can under certain conditions shrink inexorably on 100-1000 orbit timescales and form 10-100km diameter sandpile planetesimals. The typical sizes of planetesimals and the rate of their formation [7,8] are determined by a statistical model with properties inferred from large numerical simulations of turbulence [9]. Nebula turbulence can be described by its Reynolds number Re = L/eta sup(4/3), where L = ETA alpha sup (1/2) the largest eddy scale, H is the nebula gas vertical scale height, and a the nebula turbulent viscosity parameter, and ? is the Kolmogorov or smallest scale in turbulence (typically about 1km), with eddy turnover time t?. In the nebula, Re is far larger than any numerical simulation can

  15. Nitrogen metabolism and route of excretion in beef feedlot cattle fed barley-based backgrounding diets varying in protein concentration and rumen degradability.

    Science.gov (United States)

    Koenig, K M; Beauchemin, K A

    2013-05-01

    The objectives of the study were to characterize the effects of CP concentration and ruminal degradability of barley-based backgrounding diets on route and chemical form of N excretion, ruminal fermentation, microbial protein synthesis, and nutrient digestion in beef cattle. Four Angus heifers (479 ± 14.6 kg average BW) with ruminal and duodenal cannulas were used in an experiment designed as a 4 × 4 Latin square. The basal diet consisted of 54% barley silage and 46% barley grain-based concentrate (DM basis). Dietary treatments included the basal diet with no added protein (12% CP) or diets formulated to contain 14% CP by supplementation with urea (UREA), urea and canola meal (UREA+CM), or urea, corn gluten meal, and xylose-treated soybean meal (UREA+CGM+xSBM). The amount of feed offered was restricted to 95% of ad libitum intake. There was no effect of the diets on DMI (P = 0.38), and therefore, N intake was less (P 0.10) on the amount of urine N output. Urine N output was 38.9 and 45.1 ± 5.50% of N intake in heifers fed the 12% CP and 14% CP diets (P < 0.05), respectively. Urea N, the form of N most susceptible to NH3-N volatilization and loss, was the major form of N in urine (75.5% in heifers fed the 12% CP diet and 81.4 ± 1.7% in heifers fed the 14% CP diets; P < 0.05). Supplemental RDP (UREA+CM) and RUP combined with urea (UREA+CGM+xSBM) to provide 14% CP increased (P < 0.05) ruminal NH3-N but had no effect on ruminal peptide N (P = 0.62) and free AA N (P = 0.18) concentration, the flow of microbial (P = 0.34) and feed (P = 0.55) N, and ruminal (starch, P = 0.11; NDF, P = 0.78) and total tract nutrient digestibility (OM, P = 0.21; starch, P = 0.16). Supplementation of barley-based backgrounding diets containing 12% CP with NPN alone or combined with ruminally degradable and undegradable true protein to attain 14% CP had no effect on fecal N output, but urine N and urea N increased irrespective of protein source. In addition, the ruminal degradability of

  16. Rapid, Long-term Monitoring of CO2 Concentration and δ13CO2 at CCUS Sites Allows Discrimination of Leakage Patterns from Natural Background Values

    Science.gov (United States)

    Galfond, B.; Riemer, D. D.; Swart, P. K.

    2014-12-01

    In order for Carbon Capture Utilization and Storage (CCUS) to gain wide acceptance as a method for mitigating atmospheric CO2 concentrations, schemes must be devised to ensure that potential leakage is detected. New regulations from the US Environmental Protection Agency require monitoring and accounting for Class VI injection wells, which will remain a barrier to wide scale CCUS deployment until effective and efficient monitoring techniques have been developed and proven. Monitoring near-surface CO2 at injection sites to ensure safety and operational success requires high temporal resolution CO2 concentration and carbon isotopic (δ13C) measurements. The only technologies currently capable of this rapid measurement of δ13C are optical techniques such as Cavity Ringdown Spectroscopy (CRDS). We have developed a comprehensive remote monitoring approach using CRDS and a custom manifold system to obtain accurate rapid measurements from a large sample area over an extended study period. Our modified Picarro G1101-i CRDS allows for automated rapid and continuous field measurement of δ13CO2 and concentrations of relevant gas species. At our field site, where preparations have been underway for Enhanced Oil Recovery (EOR) operations, we have been able to measure biogenic effects on a diurnal scale, as well as variation due to precipitation and seasonality. Taking these background trends into account, our statistical treatment of real data has been used to improve signal-to-noise ratios by an order of magnitude over published models. Our system has proven field readiness for the monitoring of sites with even modest CO2 fluxes.

  17. Efficient hyperentanglement concentration for N-particle Greenberger-Horne-Zeilinger state assisted by weak cross-Kerr nonlinearity

    Science.gov (United States)

    Liu, Huan-Juan; Xia, Yan; Song, Jie

    2016-05-01

    In this scheme, based on the weak cross-Kerr nonlinearity, an hyperconcentration protocol for the arbitrary partially hyperentangled N-particle Greenberger-Horne-Zeilinger (GHZ) state is presented. Considering the N photons initially in the nonmaximally hyperentangled GHZ state in which photons are entangled simultaneously in the polarization and the spatial-mode degrees of freedom, we can obtain the maximally hyperentangled N-particle GHZ state by the projection measurements on the additional photons. Numerical simulation demonstrates that by iterating the entanglement concentration process, we can improve the success probability of the scheme. Furthermore, we discuss the feasibility of the setups of the protocol, concluding that the present protocol is feasible with existing experimental technology. All these advantages make this scheme more efficient and more convenient in quantum communication.

  18. Concentrations and compositions of colloidal particles in groundwater near the ICPP, Idaho National Laboratory, Idaho

    International Nuclear Information System (INIS)

    The presence of colloidal material is being investigated in groundwater near the ICPP to determine whether the concentrations and chemical compositions are suitable to have an impact on the transport of Sr-90. Colloids are proposed as a viable transport mechanism, and may have an influence on the chemical trends observed in three wells near the ICPP. Ultrafiltration of groundwater samples has been performed on difFerent intervals in USGS wells 45, 46, and Site 14, has provided filtrate samples, for analyses by ICP-MS, and filters for analyses by SEM/EDS. Preliminary results indicate that concentrations of colloids are from 2.1-0.8 ppm for the >0.45 μm size fraction, and 2.3-9.8 ppm for the <0.45 μm size fractions. Compositions consist of calcite, silicic acid, ferrihydrite, clay, and possibly dolomite. Calcium was shown to have the largest contribution from both EDS and ICP-MS. Magnesium and silicon were also found to filter out in large concentrations. Iron and aluminum are minor constituents of the colloidal mass and contain concentrations of <10ppb and <1ppb, respectively. These results indicate that if colloids are going to have a major impact on contaminant migration then the coprecipitation of Sr-90 with calcite and dolomite would have to be a sorption mechanism. Sorption onto Fe and Al colloids probably does not have a major impact because of the low concentrations. Clay colloids were noted to be relatively abundant and may also have an impact on Sr-90 migration, due to the exchange of Sr with other cations in the clay structure. 14 refs., 4 figs., 2 tabs

  19. Concentration and vertical flux of Fukushima-derived radiocesium in sinking particles from two sites in the Northwestern Pacific Ocean

    Directory of Open Access Journals (Sweden)

    M. C. Honda

    2013-06-01

    Full Text Available At two stations in the western North Pacific, K2 in the subarctic gyre and S1 in the subtropical gyre, time-series sediment traps were collecting sinking particles when the Fukushima Daiichi Nuclear Power Plant (FNPP1 accident occurred on 11 March 2011. Radiocesium (134Cs and 137Cs derived from the FNPP1 accident was detected in sinking particles collected at 500 m in late March 2011 and at 4810 m in early April 2011 at both stations. The sinking velocity of 134Cs and 137Cs was estimated to be 22 to 71 m day−1 between the surface and 500 m and >180 m day−1 between 500 m and 4810 m. 137Cs concentrations varied from 0.14 to 0.25 Bq g−1 dry weight. These values are higher than those of surface seawater, suspended particles, and zooplankton collected in April 2011. Although the radiocesium may have been adsorbed onto or incorporated into clay minerals, correlations between 134Cs and lithogenic material were not always significant; therefore, the form of the cesium associated with the sinking particles is still an open question. The total 137Cs inventory by late June at K2 and by late July at S1 was 0.5 to 1.7 Bq m−2 at both depths. Compared with 137Cs input from both stations by April 2011, estimated from the surface 137Cs concentration and mixed-layer depth and by assuming that the observed 137Cs flux was constant throughout the year, the estimated removal rate of 137Cs from the upper layer (residence time in the upper layer was 0.3 to 1.5% yr−1 (68 to 312 yr. The estimated removal rates and residence times are comparable to previously reported values after the Chernobyl accident (removal rate: 0.2–1%, residence time: 130–390 yr.

  20. Applicability of a noise-based model to estimate in-traffic exposure to black carbon and particle number concentrations in different cultures.

    Science.gov (United States)

    Dekoninck, Luc; Botteldooren, Dick; Panis, Luc Int; Hankey, Steve; Jain, Grishma; S, Karthik; Marshall, Julian

    2015-01-01

    Several studies show that a significant portion of daily air pollution exposure, in particular black carbon (BC), occurs during transport. In a previous work, a model for the in-traffic exposure of bicyclists to BC was proposed based on spectral evaluation of mobile noise measurements and validated with BC measurements in Ghent, Belgium. In this paper, applicability of this model in a different cultural context with a totally different traffic and mobility situation is presented. In addition, a similar modeling approach is tested for particle number (PN) concentration. Indirectly assessing BC and PN exposure through a model based on noise measurements is advantageous because of the availability of very affordable noise monitoring devices. Our previous work showed that a model including specific spectral components of the noise that relate to engine and rolling emission and basic meteorological data, could be quite accurate. Moreover, including a background concentration adjustment improved the model considerably. To explore whether this model could also be used in a different context, with or without tuning of the model parameters, a study was conducted in Bangalore, India. Noise measurement equipment, data storage, data processing, continent, country, measurement operators, vehicle fleet, driving behavior, biking facilities, background concentration, and meteorology are all very different from the first measurement campaign in Belgium. More than 24h of combined in-traffic noise, BC, and PN measurements were collected. It was shown that the noise-based BC exposure model gives good predictions in Bangalore and that the same approach is also successful for PN. Cross validation of the model parameters was used to compare factors that impact exposure across study sites. A pooled model (combining the measurements of the two locations) results in a correlation of 0.84 when fitting the total trip exposure in Bangalore. Estimating particulate matter exposure with traffic

  1. New Small LWR Core Designs using Particle Burnable Poisons for Low Boron Concentration

    International Nuclear Information System (INIS)

    The soluble boron has two major important roles in commercial PWR operations : 1) the control of the long-term reactivity to maintain criticality under normal operation, and 2) the shutdown of the reactor under accidents. However, the removal of the soluble boron gives several advantages in SMRs (Small Modular Reactor). These advantages resulted from the elimination of soluble boron include the significant simplification of nuclear power plant through the removal of pipes, pumps, and purification systems. Also, the use of soluble boron mitigates corrosion problems on the primary coolant loop. Furthermore, the soluble boron-free operation can remove an inadvertent boron dilution accident (BDA) which can lead to a significant insertion of positive reactivity. From the viewpoint of core physics, the removal of soluble boron or reduction of soluble boron concentration makes the moderator temperature coefficient (MTC) more negative. From the core design studies using new fuel assemblies, it is shown that the cores have very low critical soluble boron concentrations less than 500ppm, low peaking factors within the design targets, strong negative MTCs over cycles, and large enough shutdown margins both at BOC and EOC. However, the present cores have relatively low average discharge burnups of ∼ 30MWD/kg leading to low fuel economy because the cores use lots of non-fuel burnable poison rods to achieve very low critical boron concentrations. So, in the future, we will perform the trade-off study between the fuel discharge burnup and the boron concentrations by changing fuel assembly design and the core loading pattern

  2. Real-time texture analysis for identifying optimum microbubble concentration in 2-D ultrasonic particle image velocimetry.

    Science.gov (United States)

    Niu, Lili; Qian, Ming; Yan, Liang; Yu, Wentao; Jiang, Bo; Jin, Qiaofeng; Wang, Yanping; Shandas, Robin; Liu, Xin; Zheng, Hairong

    2011-08-01

    Many recent studies on ultrasonic particle image velocimetry (Echo PIV) showed that the accuracy of two-dimensional (2-D) flow velocity measured depends largely on the concentration of ultrasound contrast agents (UCAs) during imaging. This article presents a texture-based method for identifying the optimum microbubble concentration for Echo PIV measurements in real-time. The texture features, standard deviation of gray level, and contrast, energy and homogeneity of gray level co-occurrence matrix were extracted from ultrasound contrast images of rotational and pulsatile flow (10 MHz) in vitro and in vivo mouse common carotid arterial flow (40 MHz) with UCAs at various concentrations. The results showed that, at concentration of 0.8∼2 × 10³ bubbles/mL in vitro and 1∼5 × 10⁵ bubbles/mL in vivo, image texture features had a peak value or trough value, and velocity vectors with high accuracy can be obtained. Otherwise, poor quality velocity vectors were obtained. When the texture features were used as a feature set, the accuracy of K-nearest neighbor classifier can reach 86.4% in vitro and 87.5% in vivo, respectively. The texture-based method is shown to be able to quickly identify the optimum microbubble concentration and improve the accuracy for Echo PIV imaging.

  3. Investigating near-road particle number concentrations along a busy urban corridor with varying built environment characteristics

    Science.gov (United States)

    Xu, Junshi; Wang, An; Hatzopoulou, Marianne

    2016-10-01

    This study aimed at capturing the determinants of near-road concentrations of ultrafine particles (UFP) using linear mixed-effects models, investigating the effects of meteorology, built environment, and traffic. In addition, the differences in the levels of UFP between both sides of the road were investigated. To reach these objectives, field measurements were conducted on 16 weekdays in the months of March and April 2015, along Papineau Avenue, a high-volume street in Montreal, Canada. Four sites were identified varying in land use, building height, and road characteristics. Air quality measurements were conducted at each location (on both sides of the road) for two consecutive hours, at four different times during the day and repeated four times, leading to a total of 16 visits per location. Traffic volume and composition was also recorded. On-site meteorological variables including wind speed, wind direction, temperature and relative humidity were collected using a portable weather station. Linear mixed-effects models with random intercept were developed for both dependent variables: the natural logarithm of the mean UFP concentration and the difference in UFP concentrations between two sides of the road. Lower temperatures and wind speeds were associated with increased UFP concentrations. Winds orthogonal to the road tended to increase UFP concentrations as well as the differences between both sides of the road. Finally, built environment variables such as the presence of open areas and buildings on both sides of the road, had a positive influence on the difference between UFP on the two sides.

  4. Pre-analysis separation and concentration of actinides in groundwater using a magnetic filtration/sorption method. I. Background and concept

    International Nuclear Information System (INIS)

    A wide variety of iron oxides has been used for the removal of radioactive and toxic metals from aqueous solutions. Natural magnetite and iron ferrite (FeO x Fe2O3) in a batch mode to remove actinides (Pu and Am) from wastewater have been utilized. Compared to the batch process, enhanced capacity for actinide removal was observed using supported magnetite in a column surrounded by an external magnetic field (0.3 tesla). The enhanced magnetite capacity in the column is primarily due to magnetic filtration of colloidal and submicron actinide particles along with some actinide complex and ion exchange sorption mechanisms. The removal of the magnetic field from around the column and use of a regenerating solution will easily remove the actinides loaded on the magnetite. The magnetic field-enhanced column process is under development for a variety of applications. Previous work on using ferrites for water treatment is reviewed and the potential for using the magnetic field-enhanced column process as a pre-analysis separation and concentration method for actinides in groundwater is discussed. (author)

  5. Investigation on particle matter concentration and bacterial bioaerosols in indoor air of prisons

    Directory of Open Access Journals (Sweden)

    Mohammad Sadegh Sekhavatjou

    2014-03-01

    Conclusion: Based on the results, the maximum contamination load and exceeded concentration was observed in public sections and bedchambers. This findings were attributed to the daily entry of new prisoners, high population density in prison, presence of ill prisoners, prisoners with hidden respiratory disease showing no symptoms yet, old building, climatic conditions of the region, low efficiency of ventilation systems, and influx of particulates. To filter and purify prison indoor air, it is crucial to take serious action plans such as reducing criminal population density, sanitary and engineering measures

  6. The effect of a concentration-dependent viscosity on particle transport in a channel flow with porous walls

    KAUST Repository

    Herterich, James G.

    2014-02-02

    The transport of a dilute suspension of particles through a channel with porous walls, accounting for the concentration dependence of the viscosity, is analyzed. In particular, we study two cases of fluid permeation through the porous channel walls: (1) at a constant flux and (2) dependent on the pressure drop across the wall. We also consider the effect of mixing the suspension first compared with point injection by considering inlet concentration distributions of different widths. We find that a pessimal inlet distribution width exists that maximizes the required hydrodynamic pressure for a constant fluid influx. The effect of an external hydrodynamic pressure, to compensate for the reduced transmembrane pressure difference due to osmotic pressure, is investigated. © 2014 American Institute of Chemical Engineers.

  7. A ring-like concentration of mm-sized particles in Sz 91

    CERN Document Server

    Canovas, H; Schreiber, M R; Hardy, A; Cieza, L; Ménard, F; Hales, A

    2016-01-01

    Models of planet formation and disc evolution predict a variety of observables in the dust structure of protoplanetary discs. Here we present Atacama Large Millimeter/submillimeter Array (ALMA) Band-6 and Band-7 observations of the transition disc Sz\\,91 showing that the continuum emission at 870$\\mu$m, which is dominated by emission from large dust grains, is localized in an optically thin narrow ring. We find that most of the emission ($\\sim95\\%$) is concentrated in a ring located at 110 au from the central star that is only about 44 au wide. In contrast, the $^{12}\\mathrm{CO}$ (2-1) emission peaks closer to the star and is detected up to $\\sim488$ au from the star. The concentration of large grains in a ring-like structure while the gas disc extends much further in and further out is in qualitative agreement with predictions of hydrodynamical models of planet-disc interactions including radial drift and gas drag.

  8. Emission of β+ Particles Via Internal Pair Production in the 0+ – 0+ Transition of 90Zr: Historical Background and Current Applications in Nuclear Medicine Imaging

    Directory of Open Access Journals (Sweden)

    Marco D'Arienzo

    2013-03-01

    Full Text Available 90Y is traditionally considered as a pure β– emitter. However, the decay of this radionuclide has a minor branch to the 0+ first excited state of 90Zr at 1.76 MeV, that is followed by a β+/β– emission. This internal pair production has been largely studied in the past because it is generated by a rare electric monopole transition (E0 between the states 0+/0+ of 90Zr. The positronic emission has been recently exploited for nuclear medicine applications, i.e. positron emission tomography (PET acquisitions of 90Y-labelled radiopharmaceuticals, widely used as therapeutic agents in internal radiation therapy. To date, this topic is gaining increasing interest in the radiation dosimetry community, as the possibility of detecting β+ emissions from 90Y by PET scanners may pave the way for an accurate patient-specific dosimetry. This could lead to an explosion in scientific production in this field. In the present paper the historical background behind the study of the internal pair production of the 0+/0+ transition of 90Zr is presented along with most up to date measured branch ratio values. An overview of most recent studies that exploit β+ particles emitted from 90Y for PET acquisitions is also provided.

  9. The Chrono'Geometrical Structure of Special and General Relativity: Towards a Background-Independent Description of the Gravitational Field and Elementary Particles

    CERN Document Server

    Lusanna, Luca

    2004-01-01

    Since the main open problem of contemporary physics is to find a unified description of the four interactions, we present a possible scenario which, till now only at the classical level, is able to englobe experiments ranging from experimental space gravitation to atomic and particle physics. After a reformulation of special relativistic physics in a form taking into account the non-dynamical chrono-geometrical structure of Minkowski space-time (parametrized Minkowski theories and rest-frame instant form) and in particular the conventionality of simultaneity (re-phrased as a gauge freedom), a model of canonical metric and tetrad gravity is proposed in a class of space-times where the deparametrization to Minkowski space-time is possible. In them it is possible to give a post-Minkowskian background-independent description of the gravitational field and of matter. The study of the dynamical chrono-geometrical structure of these space-times allows to face interpretational problems like the physical identificatio...

  10. Structural and optical properties of SrS nanophosphors influenced by Ce3+ ions concentrations and particle size reduction

    Science.gov (United States)

    Mishra, Shubhra; Khare, Ayush; Kshatri, D. S.; Tiwari, Sanjay

    2015-10-01

    The SrS nanophosphors doped with different concentrations of Ce3+ are synthesized by solid state diffusion method (SSDM). Various characterization and spectral studies are reported in the light of varied dopant concentrations and reduction in particle size by milling. The as-obtained phosphors are characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) including selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopic (EDX) studies. The FESEM and HRTEM results explain the surface morphology, agglomeration of particles, crystallite size, etc. The results of XRD studies confirm the cubic structure of most intense SrS: Ce3+ nanophosphors and exhibit wider diffraction peaks for 4 h milled sample. The EDX profiles are used to authenticate the occurrence of different starting materials in final products. Upon excitation with UV light (375 nm), two emission peaks are observed at around 459 nm and 551 nm due to transitions of electrons from the 2T2g(5d) → 2F5/2(4f) and 2T2g(5d) → 2F7/2(4f) energy levels. The afterglow decay behavior of different SrS: Ce3+ nanophosphors is presented and discussed systematically.

  11. Atmospheric concentration characteristics and gas-particle partitioning of PCBs in a rural area of eastern Germany

    Energy Technology Data Exchange (ETDEWEB)

    Mandalakis, Manolis [Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, P.O. Box 2208, GR-71003, Heraklion (Greece)]. E-mail: mandalakis@chemistry.uoc.gr; Stephanou, Euripides G. [Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, P.O. Box 2208, GR-71003, Heraklion (Greece)

    2007-05-15

    Atmospheric concentrations of polychlorinated biphenyls (PCBs) were measured in 14 successive daytime and nighttime air samples collected from Melpitz, a rural site in eastern Germany. The average total concentration of PCBs was 110+/-80pgm{sup -3} and they were predominately present in the gas phase ({approx}95%). Composition of individual congeners closely resembled those of Clophen A30 and Aroclor 1232. Partial vapor pressures of PCBs were well correlated with temperature and the steep slopes obtained from Clausius-Clapeyron plots (-4500 to -8000) indicated that evaporation from adjacent land surfaces still controls the atmospheric levels of these pollutants. Particle-gas partitioning coefficients (K{sub P}) of PCBs were well correlated with the respective sub-cooled vapor pressures (P{sub L}{sup o}), but the slopes obtained from logK{sub P} versus logP{sub L}{sup o} plots (-0.16 to -0.59) deviated significantly from the expected value of -1. Overall, gas-particle partitioning of PCBs was better simulated by Junge-Pankow than octanol/air partition coefficient-based model.

  12. Investigation of background concentration of phosphate in raw meat%原料肉中磷酸盐本底含量状况调查与分析

    Institute of Scientific and Technical Information of China (English)

    臧明伍; 孙焕; 史智佳; 吕玉; 乔晓玲

    2012-01-01

    运用比色法,先后对5类1353个生肉样品、5类121个副产品样品,共计1474个原料肉样品进行了磷酸盐本底含量的测定。结果表明,原料肉中磷酸盐本底含量范围为1.49~16.5g/kg,多数处于低端水平;不同种类的生肉中磷酸盐含量存在显著差异(P〈0.05),其中生猪肉中磷酸盐含量最高,其次为鸭肉,生羊肉中磷酸盐含量最低;不同种类的副产物中磷酸盐含量存在显著差异(P〈0.05),其中生猪肝中磷酸盐含量最高,其次为生牛肝,生猪肠、肺中磷酸盐含量最低。%The background concentrations of phosphate in 1474 raw meat samples,including 1353 samples of 5 species of raw meat,121 samples of 5 species of byproducts,were determined by colorimetry.The results showed that the scope of concentrations of phosphate in raw meat was 1.49~16.5g/kg,most of the samples had low concentration.While phosphate content in pork seem to be significantly higher than other raw meat species(P0.05),followed by raw duck meat,however,the content in mutton was the lowest.Phosphate content in pork liver also seem to be significantly higher than other byproducts(P0.05),followed by bovine liver.The content in pork chitterlings and lung was the lowest.

  13. Atmospheric concentration characteristics and gas/particle partitioning of PCBs from the North Pacific to the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    WANG Zhen; NA Guangshui; GAO Hui; WANG Yanjie; YAO Ziwei

    2014-01-01

    Polychlorinated biphenyls (PCBs) were measured in atmospheric samples collected from the North Pacific to the Arctic Ocean between July and September 2012 to study the atmospheric concentration characteris-tics of PCBs and their gas/particle partitioning. The mean concentration of 26 PCBs (vapor plus particulate phase) (ƩPCBs) was 19.116 pg/m3with a standard deviation of 13.833 pg/m3. Three most abundant conge-ners were CB-28, -52 and -77, accounting for 43.0% toƩPCBs. The predominance of vapor PCBs (79.0% toƩPCBs) in the atmosphere was observed.ƩPCBs were negative correlated with the latitudes and inverse of the absolute temperature (1/T). The significant correlation for most congeners was also observed between the logarithm of gas/particle partition coefficient (logKP) and 1/T. Shallower slopes (from −0.15 to −0.46, average −0.27) were measured from the regression of the logarithm of sub-cooled liquid vapor pressures (logpºL) and logKP for all samples. The difference of the slopes and intercepts among samples was insignifi-cant (p>0.1), implying adsorption and/or absorption processes and the aerosol composition did not differ significantly among different samples. By comparing three models, the J-P adsorption model, the octanol/air partition coefficient (KOA) based model and the soot-air model, the gas/particle partitioning of PCBs in the Arctic atmosphere was simulated more precisely by the soot-air model, and the adsorption onto el-emental carbon is more sensitive than the absorption into organic matters of aerosols, especially for low-chlorinated PCB congeners.

  14. Springtime carbon emission episodes at the Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

    Science.gov (United States)

    Jung, J.; Kawamura, K.

    2011-11-01

    In order to investigate the emission of carbonaceous aerosols at the Gosan background super-site (33.17° N, 126.10° E) in East Asia, total suspended particles (TSP) were collected during spring of 2007 and 2008 and analyzed for particulate organic carbon, elemental carbon, total carbon (TC), total nitrogen (TN), and stable carbon isotopic composition (δ13C) of TC. The stable carbon isotopic composition of TC (δ13CTC) was found to be lowest during pollen emission episodes (range: -26.2‰ to -23.5‰, avg. -25.2 ± 0.9‰), approaching those of the airborne pollen (-28.0‰) collected at the Gosan site. Based on a carbon isotope mass balance equation, we found that ~42% of TC in the TSP samples during the pollen episodes was attributed to airborne pollen from Japanese cedar trees planted around tangerine farms in Jeju Island. A negative correlation between the citric acid-carbon/TC ratios and δ13CTC was obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollen and then transported to the Gosan site. Thermal evolution patterns of organic carbon during the pollen episodes were characterized by high OC evolution in the OC2 temperature step (450 °C). Since thermal evolution patterns of organic aerosols are highly influenced by their molecular weight, they can be used as additional information on the formation of secondary organic aerosols and the effect of aging of organic aerosols during the long-range atmospheric transport and sources of organic aerosols.

  15. Springtime carbon emission episodes at the Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

    Directory of Open Access Journals (Sweden)

    J. Jung

    2011-11-01

    Full Text Available In order to investigate the emission of carbonaceous aerosols at the Gosan background super-site (33.17° N, 126.10° E in East Asia, total suspended particles (TSP were collected during spring of 2007 and 2008 and analyzed for particulate organic carbon, elemental carbon, total carbon (TC, total nitrogen (TN, and stable carbon isotopic composition (δ13C of TC. The stable carbon isotopic composition of TC (δ13CTC was found to be lowest during pollen emission episodes (range: −26.2‰ to −23.5‰, avg. −25.2 ± 0.9‰, approaching those of the airborne pollen (−28.0‰ collected at the Gosan site. Based on a carbon isotope mass balance equation, we found that ~42% of TC in the TSP samples during the pollen episodes was attributed to airborne pollen from Japanese cedar trees planted around tangerine farms in Jeju Island. A negative correlation between the citric acid-carbon/TC ratios and δ13CTC was obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollen and then transported to the Gosan site. Thermal evolution patterns of organic carbon during the pollen episodes were characterized by high OC evolution in the OC2 temperature step (450 °C. Since thermal evolution patterns of organic aerosols are highly influenced by their molecular weight, they can be used as additional information on the formation of secondary organic aerosols and the effect of aging of organic aerosols during the long-range atmospheric transport and sources of organic aerosols.

  16. QUANTITATIVE ASSESSMENT OF POLYMETALLIC POLLUTION OF THE DNIEPER RIVER BY A METHOD OF HEAVY METALS BACKGROUND CONCENTRATION CALCULATION IN MUSSEL ANODONTA ANATINA

    OpenAIRE

    D. V. Lukashov

    2009-01-01

    Statistically significant exceeding of a background level of the heavy metal content in Anodonta anatina (Linnaeus, 1758) soft tissues was applied for pollution measure. The method of the median absolute deviation (MAD) was used for the heavy metals’ background and threshold levels assessment. The comparison of metal contents in mussels from 23 studied area of Ukrainian part of the Dnieper with the calculated background level allowed to determine the pollution degree of some river’s sites.

  17. Nature of Atmospheric Aerosols over the Desert Areas in the Asian Continent: Chemical State and Number Concentration of Particles Measured at Dunhuang, China

    International Nuclear Information System (INIS)

    Measurements of aerosol were made in August and October 2001, and January 2002, at Dunhuang, China (40o00'N, 94o30'E), to understand the nature of atmospheric particles over the desert areas in the Asian continent. Balloon-borne measurements with an optical particle counter suggested that particle size and concentration had a noticeable peak in size range of super micron in not only the boundary mixing layer but also the free troposphere. Thickness of the boundary mixing layer, from distributions of particle concentration, was about 4 km in summer (17 August 2001), about2.5 km in fall (17 October 2001), and about 3 km in winter (11 January 2002), which suggest active mixing of particles near the boundary in summer. Number-size distribution of particle showed a noticeable peak in the super micron particles size range in the mixing boundary layer: 0.4-2 particles cm-3 at diameter>1.2 μm in summer, 0.05-4 particles cm-3 at diameter >1.2 μm in fall, and 0.1-5 particles cm-3 at diameter>1.2 μm in winter. In winter strong inversion of atmospheric temperature was found in the height range from the boundary to about 3 km and vertical distribution of particle concentration well corresponded with the temperature distribution. Chemical elements of individual aerosols, which were collected in the boundary layer atmosphere at Dunhuang (18 October 2001) were analyzed with an electron microscope equipped with EDX. Those single particle analysis suggested that most of the particles with supermicron size were soil particles, and those particles had little sulfate on its surface. This is a very important different point,comparing with the chemical state of soil particles, which were transported from the desert area of China to Japan, and showed frequently the existence of sulfate on the particle surface. Therefore, it is strongly suggested that dust particles can be chemically modified during their long-range transport from desert areas to Japan

  18. Effect of flexibility on the growth of concentration fluctuations in a suspension of sedimenting fibers: Particle simulations

    Energy Technology Data Exchange (ETDEWEB)

    Manikantan, Harishankar; Saintillan, David [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093 (United States)

    2016-01-15

    Three-dimensional numerical simulations are performed to study the stability of a sedimenting suspension of weakly flexible fibers. It is well known that a suspension of rigid rods sedimenting under gravity at low Reynolds number is unstable to concentration fluctuations owing to hydrodynamic interactions. Flexible fibers, however, reorient while settling and even weak flexibility can alter their collective dynamics. In our recent work [Manikantan et al., “The instability of a sedimenting suspension of weakly flexible fibres,” J. Fluid Mech. 756, 935–964 (2014)], we developed a mean-field theory to predict the linear stability of such a system. Here, we verify these predictions using accurate and efficient particle simulations based on a slender-body model. We also demonstrate the mechanisms by which flexibility-induced reorientation alters suspension microstructure, and through it, its stability. Specifically, we first show that the anisotropy of the base state in the case of a suspension of flexible fibers has a destabilizing effect compared to a suspension of rigid rods. Second, a conflicting effect of flexibility is also shown to suppress particle clustering and slow down the growth of the instability. The relative magnitude of filament flexibility and rotational Brownian motion dictates which effect dominates, and our simulations qualitatively follow theoretically predicted trends. The mechanism for either effects is tied to the flexibility-induced reorientation of particles, which we illustrate using velocity and orientation statistics from our simulations. Finally, we also show that, in the case of an initially homogeneous and isotropic suspension, flexibility always acts to suppress the growth of the instability.

  19. Dissipative particle dynamics simulation of flow generated by two rotating concentric cylinders: II. Lateral dissipative and random forces

    International Nuclear Information System (INIS)

    Traditional DPD methods address dissipative and random forces exerted along the line connecting neighbouring particles. Espanol (1998 Phys. Rev. E 57 2930-48) suggested adding dissipative and random force components in a direction perpendicular to this line. This paper focuses on the advantages and disadvantages of such an addition as compared with the traditional DPD method. Our benchmark system comprises fluid initially at rest occupying the space between two concentric cylinders rotating with various angular velocities. The effect of the lateral force components on the time evolution of the simulated velocity profile was also compared with that of the known analytical solution. The results show that (i) the solution accuracy at steady state has improved and the error has been reduced by at least 30% (in one case by 75%), (ii) the DPD time to reach steady state has been halved, (iii) the CPU time has increased by only 30%, and (iv) no significant differences exist in density and temperature distributions

  20. Dissipative particle dynamics simulation of flow generated by two rotating concentric cylinders: II. Lateral dissipative and random forces

    Energy Technology Data Exchange (ETDEWEB)

    Filipovic, N [Faculty of Mechanical Engineering, University of Kragujevac (Serbia); Haber, S [Technion-Israel Institute of Technology, Haifa (Israel); Kojic, M [Faculty of Mechanical Engineering, University of Kragujevac (Serbia); Tsuda, A [Harvard School of Public Health, Harvard University, Boston, MA (United States)

    2008-02-07

    Traditional DPD methods address dissipative and random forces exerted along the line connecting neighbouring particles. Espanol (1998 Phys. Rev. E 57 2930-48) suggested adding dissipative and random force components in a direction perpendicular to this line. This paper focuses on the advantages and disadvantages of such an addition as compared with the traditional DPD method. Our benchmark system comprises fluid initially at rest occupying the space between two concentric cylinders rotating with various angular velocities. The effect of the lateral force components on the time evolution of the simulated velocity profile was also compared with that of the known analytical solution. The results show that (i) the solution accuracy at steady state has improved and the error has been reduced by at least 30% (in one case by 75%), (ii) the DPD time to reach steady state has been halved, (iii) the CPU time has increased by only 30%, and (iv) no significant differences exist in density and temperature distributions.

  1. 微细粒重选技术研究%A Study of the Gravity Concentration Technology on Superfine Particles

    Institute of Scientific and Technical Information of China (English)

    魏镜弢; 杨波

    2001-01-01

    The effective method of recovering superfine heavy mineral is a new saperfine gravity equipment being developed.Recovering superfine particle in centrifugal field can strengthen the effect of separation.This paper introduces the feature of MGS,Knelson concentrator and superfine centrifugal jigger.To counter the deficiency of superfine gravity equipment available,it goes further into the train of thought of gravity concetration technology on superfine particle.%微细粒重选设备的开发,是回收微细粒重矿物的有效方法.在高心力场内回收微细粒颗粒,可强化分选效果.分别介绍了多重力分选机、Knelson选矿机、微细粒离心跳汰机的特点.针对现有细粒重选设备的不足之处,探讨了微细粒重选的发展思路.

  2. Elevated Concentrations of Lead in Particulate Matter on the Neighborhood-Scale in Delhi, India As Determined by Single Particle Analysis.

    Science.gov (United States)

    Shen, Hongru; Peters, Thomas M; Casuccio, Gary S; Lersch, Traci L; West, Roger R; Kumar, Amit; Kumar, Naresh; Ault, Andrew P

    2016-05-17

    High mass concentrations of atmospheric lead particles are frequently observed in the Delhi, India metropolitan area, although the sources of lead particles are poorly understood. In this study, particles sampled across Delhi (August - December 2008) were analyzed by computer-controlled scanning electron microscopy with energy dispersive X-ray spectroscopy (CCSEM-EDX) to improve our understanding of the spatial and physicochemical variability of lead-rich particles (>90% lead). The mean mass concentration of lead-rich particles smaller than 10 μm (PM10) was 0.7 μg/m(3) (1.5 μg/m(3) std. dev.) with high variability (range: 0-6.2 μg/m(3)). Four samples (16% of 25 samples) with PM10 lead-rich particle concentrations >1.4 μg/m(3) were defined as lead events and studied further. The temporal characteristics, heterogeneous spatial distribution, and wind patterns of events, excluded regional monsoon conditions or common anthropogenic sources from being the major causes of the lead events. Individual particle composition, size, and morphology analysis indicate informal recycling operations of used lead-acid batteries as the likely source of the lead events. This source is not typically included in emission inventories, and the observed isolated hotspots with high lead concentrations could represent an elevated exposure risk in certain neighborhoods of Delhi.

  3. Concentration and size distribution of particulate oxalate in marine and coastal atmospheres - Implication for the increased importance of oxalate in nanometer atmospheric particles

    Science.gov (United States)

    Guo, Tianfeng; Li, Kai; Zhu, Yujiao; Gao, Huiwang; Yao, Xiaohong

    2016-10-01

    In literature, particulate oxalate has been widely studied in the total suspended particles (TSP), particles 100 nm. In this article, we measured oxalate's concentrations in size-segregated atmospheric particles down to 10 nm or 56 nm during eight campaigns performed at a semi-urban coastal site, over the marginal seas of China and from the marginal seas to the northwest Pacific Ocean (NWPO) in 2012-2015. When the sum of the oxalate's concentration in particles values of 0.05-0.06 μg m-3 were observed during the two campaigns performed at NWPO. The highest average value of 0.38 μg m-3 was observed at the coastal site during a heavy pollution event. Mode analysis results of particulate oxalate and the correlation between oxalate and sulfate suggested that the elevated concentrations of oxalate in PM10 were mainly related to enhanced in-cloud formation of oxalate via anthropogenic precursors. Size distribution data in the total of 136 sets of samples also showed approximately 80% of particulate oxalate's mass existing in atmospheric particles >100 nm. Consistent with previous studies, particulate oxalate in particles >100 nm was a negligible ionic component when comparing to particulate SO42- in the same size range. However, the mole ratios of oxalate/sulfate in particles 100 nm atmospheric particles such as PM2.5, PM10, TSP, etc.

  4. Effect of Concentration and Surface Property of Silica Sol on the Determination of Particle Size and Electrophoretic Mobility by Light Scattering Method

    International Nuclear Information System (INIS)

    Colloidal silica is used in various industrial products such as chemical mechanical polishing slurry for planarization of silicon and sapphire wafer, organic-inorganic hybrid coatings, binder of investment casting, etc. An accurate determination of particle size and dispersion stability of silica sol is demanded because it has a strong influence on surface of wafer, film of coatings or bulks having mechanical, chemical and optical properties. The study herein is discussed on the effect of measurement results of average particle size, sol viscosity and electrophoretic mobility of particle according to the volume fraction of eight types of silica sol with different size and surface properties of silica particles which are presented by the manufacturer. The measured particle size and the mobility of these sol were changed by volume fraction or particle size due to highly active surface of silica particle and change of concentration of counter ion by dilution of silica sol. While in case the measured sizes of small particles less than 60 nm are increased with increasing volume fraction, the measured sizes of larger particles than 60 nm are slightly decreased. The mobility of small particle such as 12 nm are decreased with increase of viscosity. However, the mobility of 100 nm particles under 0.048 volume fraction are increased with increasing volume fraction and then decreased over higher volume fraction

  5. Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds.

    Science.gov (United States)

    Wei, Wenjuan; Mandin, Corinne; Blanchard, Olivier; Mercier, Fabien; Pelletier, Maud; Le Bot, Barbara; Glorennec, Philippe; Ramalho, Olivier

    2016-09-01

    The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25°C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R>0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6°C, while it increased by up to 750% when the indoor temperature increased from 15°C to 30°C. PMID:27152992

  6. Effects of subchronic exposures to concentrated ambient particles (CAPs) in mice. I. Introduction, objectives, and experimental plan.

    Science.gov (United States)

    Lippmann, Morton; Gordon, Terry; Chen, Lung Chi

    2005-04-01

    This subchronic (6-mo) inhalation study of the effects of concentrated ambient air fine particulate matter (PM2.5) in normal mice (C57) and a murine model of humans with an advanced level of aortic plaque (ApoE-/- or ApoE-/- LDLr-/-) was designed to determine the presence and extent of a variety of health-related responses. The animals were exposed for 6 h/day, 5 day/wk during the spring and summer of 2003 to concentrations that were elevated 10-fold in Tuxedo, NY, a regional background site that is upwind and approximately 50 km west-northwest of New York City. The average PM2.5 concentration during exposure was 110 microgram/m3, and the long-term average was 19.7 microg/m3. There were substantial daily variations in concentration, and we sought evidence both for the influence of peak exposures on acute responses and for the cumulative effects of the prolonged series of exposures. Acute responses were characterized in terms of: (1) short-term electrocardiographic (EKG), core body temperature, and physical activity differences between PM and sham-exposed mice; and (2) in vitro toxicity of a simultaneously collected PM2.5 sample to lung epithelial cells. Cumulative responses to PM2.5 were characterized in terms of changes in heart rate, heart-rate variability, heart-rate variance, aortic plaque density, genetic marker expression, and brain cell distributions. There were no significant changes in the normal mice. The nature and extent of the exposure-related responses that were seen in the ApoE-/- as well as ApoE-/- LDLr-/- mice are described in the articles that follow in this special issue of Inhalation Toxicology.

  7. A comparison of strategies for estimation of ultrafine particle number concentrations in urban air pollution monitoring networks

    International Nuclear Information System (INIS)

    We propose three estimation strategies (local, remote and mixed) for ultrafine particles (UFP) at three sites in an urban air pollution monitoring network. Estimates are obtained through Gaussian process regression based on concentrations of gaseous pollutants (NOx, O3, CO) and UFP. As local strategy, we use local measurements of gaseous pollutants (local covariates) to estimate UFP at the same site. As remote strategy, we use measurements of gaseous pollutants and UFP from two independent sites (remote covariates) to estimate UFP at a third site. As mixed strategy, we use local and remote covariates to estimate UFP. The results suggest: UFP can be estimated with good accuracy based on NOx measurements at the same location; it is possible to estimate UFP at one location based on measurements of NOx or UFP at two remote locations; the addition of remote UFP to local NOx, O3 or CO measurements improves models' performance. - Highlights: • UFP number concentrations are estimated using Gaussian process regression. • The independent variables include local and/or remote gaseous measurements. • Three modelling strategies (local, remote and mixed) used for UFP estimations. • NOx was the most important independent variable. • The best models explained >90% of the variance. - UFP can be estimated with good accuracy at one location based on NOx measurements at the same location and based on measurements of NOx or UFP at two remote locations

  8. Study of the Effect of Volume Fraction Concentration and Particle Materials on Thermal Conductivity and Thermal Diffusivity of Nanofluids

    Science.gov (United States)

    Ali, Faris Mohammed; Mat Yunus, W. Mahmood

    2011-08-01

    Nanofluids, a mixture of nanoparticles and fluids, have exceptional potential to improve their effective thermal conductivity and thermal diffusivity, aluminum and aluminum oxide nanofluids with five different volume fractions of nanoparticle suspensions in different base fluids, i.e., distilled water, ethylene glycol (EG), and ethanol were prepared by mixing nanopowder and base fluids. Sonication with high-powered pulses was used to ensure the dispersion of nanoparticles in good uniformity in the base fluids. The hot wire-laser beam displacement technique was used to measure thermal conductivity and thermal diffusivity of the prepared nanofluids. The effects of the volume fraction concentration and particle materials on the thermal conductivity and thermal diffusivity of nanofluids were determined. The results showed that the thermal conductivity and thermal diffusivity increased linearly with increasing volume fraction concentration of nanoparticles in the respective base fluids. In addition, the thermal conductivity and thermal diffusivity increased faster in the Al2O3 nanofluids than in all the three base fluids.

  9. Springtime carbon episodes at Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

    Science.gov (United States)

    Jung, J.; Kawamura, K.

    2011-05-01

    In order to investigate the carbon episodes at Gosan background super-site (33.17° N, 126.10° E) in East Asia during spring of 2007 and 2008, total suspended particles (TSP) were collected and analyzed for particulate organic carbon, elemental carbon, total carbon (TC), total nitrogen (TN), and stable carbon isotopic composition (δ13C) of TC. The carbon episodes at the Gosan site were categorized as long-range transported anthropogenic pollutant (LTP) from Asian continent, Asian dust (AD) accompanying with LTP, and local pollen episodes. The stable carbon isotopic composition of TC (δ13CTC) was found to be lowest during the pollen episodes (range: -26.2 ‰ to -23.5 ‰, avg.: -25.2 ± 0.9 ‰), followed by the LTP episodes (range: -23.5 ‰ to -23.0 ‰, avg.: -23.3 ± 0.3 ‰) and the AD episodes (range: -23.3 to -20.4 %, avg.: -21.8 ± 2.0 ‰). The δ13CTC of the airborne pollens (-28.0 ‰) collected at the Gosan site showed value similar to that of tangerine fruit (-28.1 ‰) produced from Jeju Island. Based on the carbon isotope mass balance equation and the TN and TC regression approach, we found that ∼40-45 % of TC in the TSP samples during the pollen episodes was attributed to airborne pollens from Japanese cedar trees planted around tangerine farms in Jeju Island. The δ13C of citric acid in the airborne pollens (-26.3 ‰) collected at the Gosan site was similar to that in tangerine fruit (-27.4 ‰). The negative correlation between the citric acid-carbon/TC ratios and δ13CTC were obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollens and then transported to the Gosan site. Based on the thermal evolution pattern of organic aerosols during the carbon episodes, we found that organic aerosols originated from East China are more volatile on heating and are more likely to form pyrolized organic carbon than the pollen-enriched organic aerosols and organic

  10. Concentration device

    DEFF Research Database (Denmark)

    2013-01-01

    A concentration device (2) for filter filtration concentration of particles (4) from a volume of a fluid (6). The concentration device (2) comprises a filter (8) configured to filter particles (4) of a predefined size in the volume of the fluid (6). The concentration device (2) comprises...

  11. Analysis and applications of measurements of source dominated hydrocarbon concentrations from the PUMA campaigns in June/July 1999 and January/February 2000 at an urban background site in Birmingham, UK

    Science.gov (United States)

    Hopkins, J. R.; Lewis, A. C.; Seakins, P. W.

    Approximately, hourly C 2-C 7 hydrocarbon concentrations from gas chromatographic measurements are reported for an urban background site in Birmingham, UK, from summer 1999 and winter 1999-2000. Comparison with another measurement site suggests that the observed behaviour is typical of the urban background in the whole conurbation. The lack of any correlation between seasonal variation and OH rate coefficient shows that hydrocarbon concentrations are dominated by local sources. Chemical mass balance techniques have been applied and indicate the main sources are vehicle emissions (exhaust and fugitive) and natural gas leakage. Winter concentrations of isoprene correlate well with butadiene concentrations suggesting an automotive related source. This correlation disappears during the summer when isoprene displays a high correlation with radiation. During a period of the summer campaign ethane and propane concentrations displayed a regular diurnal behaviour, which has been utilized to estimate the ratios of the day/night boundary layer height and natural gas emission rates for the West Midlands conurbation.

  12. Meteorological and trace gas factors affecting the number concentration of atmospheric Aitken (Dp=50 nm particles in the continental boundary layer: parameterization using a multivariate mixed effects model

    Directory of Open Access Journals (Sweden)

    M. C. Facchini

    2010-08-01

    Full Text Available Measurements of aerosol size-distribution and different gas and meteorological parameters, made in three polluted sites in Central- and Southern Europe: Po Valley, Italy, Melpitz and Hohenpeissenberg in Germany, were analysed for this study to examine which of the meteorological and trace gas variables affect the number concentration of Aitken (Dp=50 nm particles. The aim of our study was to predict the number concentration of 50 nm particles by a combination of in-situ meteorological and gas phase parameters. The statistical model needs to describe, amongst others, the factors affecting the growth of newly formed aerosol particles (below 10 nm to 50 nm size, but also sources of direct particle emissions in that size range. As the analysis method we used multivariate nonlinear mixed effects model. Hourly averages of gas and meteorological parameters measured at the stations were used as predictor variables; the best predictive model was attained with a combination of relative humidity, new particle formation event probability, temperature, condensation sink and concentrations of SO2, NO2 and ozone. The seasonal variation was also taken into account in the mixed model structure. Model simulations with the Global Model of Aerosol Processes (GLOMAP indicate that the parameterization can be used as a part of a larger atmospheric model to predict the concentration of climatically active particles. As an additional benefit, the introduced model framework is, in theory, applicable for any kind of measured aerosol parameter.

  13. Errors analysis in the evaluation of particle concentration by PDA on a turbulent two-phase jet: application for cross section and transit time methods

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, Esteban; Garcia, Juan A.; Garcia, Ignacio; Aisa, Luis A. [University of Zaragoza, Area de Mecanica de Fluidos, Centro Politecnico Superior, Zaragoza (Spain)

    2009-09-15

    Phase-Doppler anemometry (PDA) is a powerful tool for two-phase flow measurements and testing. Particle concentration and mass flux can also be evaluated using the raw particle data supplied by this technique. The calculation starts from each particle velocity, diameter, transit time data, and the total measurement time. There are two main evaluation strategies. The first one uses the probe volume effective cross section, and it is usually simplified assuming that particles follow quasi one-directional trajectories. In the text, it will be called the cross section method. The second one includes a set of methods which will be denoted as ''Generalized Integral Methods'' (GIM). Concentration algorithms such as the transit time method (TTM) and the integral volume method (IVM) are particular cases of the GIM. In any case, a previous calibration of the measurement volume geometry is necessary to apply the referred concentration evaluation methods. In this study, concentrations and mass fluxes both evaluated by the cross-section method and the TTM are compared. Experimental data are obtained from a particle-laden jet generated by a convergent nozzle. Errors due to trajectory dispersion, burst splitting, and multi-particle signals are discussed. (orig.)

  14. Meteorological and trace gas factors affecting the number concentration of atmospheric Aitken (Dp = 50 nm particles in the continental boundary layer: parameterization using a multivariate mixed effects model

    Directory of Open Access Journals (Sweden)

    M. C. Facchini

    2011-01-01

    Full Text Available Measurements of aerosol size distribution and different gas and meteorological parameters, made in three polluted sites in Central and Southern Europe: Po Valley, Italy, Melpitz and Hohenpeissenberg in Germany, were analysed for this study to examine which of the meteorological and trace gas variables affect the number concentration of Aitken (Dp= 50 nm particles. The aim of our study was to predict the number concentration of 50 nm particles by a combination of in-situ meteorological and gas phase parameters. The statistical model needs to describe, amongst others, the factors affecting the growth of newly formed aerosol particles (below 10 nm to 50 nm size, but also sources of direct particle emissions in that size range. As the analysis method we used multivariate nonlinear mixed effects model. Hourly averages of gas and meteorological parameters measured at the stations were used as predictor variables; the best predictive model was attained with a combination of relative humidity, new particle formation event probability, temperature, condensation sink and concentrations of SO2, NO2 and ozone. The seasonal variation was also taken into account in the mixed model structure. Model simulations with the Global Model of Aerosol Processes (GLOMAP indicate that the parameterization can be used as a part of a larger atmospheric model to predict the concentration of climatically active particles. As an additional benefit, the introduced model framework is, in theory, applicable for any kind of measured aerosol parameter.

  15. Concentrations and abundance ratios of long-chain alkenones and glycerol dialkyl glycerol tetraethers in sinking particles south of Java

    Science.gov (United States)

    Chen, Wenwen; Mohtadi, Mahyar; Schefuß, Enno; Mollenhauer, Gesine

    2016-06-01

    In this study, we obtained concentrations and abundance ratios of long-chain alkenones and glycerol dialkyl glycerol tetraethers (GDGTs) in a one-year time-series of sinking particles collected with a sediment trap moored from December 2001 to November 2002 at 2200 m water depth south of Java in the eastern Indian Ocean. We investigate the seasonality of alkenone and GDGT fluxes as well as the potential habitat depth of the Thaumarchaeota producing the GDGTs entrained in sinking particles. The alkenone flux shows a pronounced seasonality and ranges from 1 μg m-2 d-1 to 35 μg m-2 d-1. The highest alkenone flux is observed in late September during the Southeast monsoon, coincident with high total organic carbon fluxes as well as high net primary productivity. Flux-weighted mean temperature for the high flux period using the alkenone-based sea-surface temperature (SST) index U37K‧ is 26.7 °C, which is similar to satellite-derived Southeast (SE) monsoon SST (26.4 °C). The GDGT flux displays a weaker seasonality than that of the alkenones. It is elevated during the SE monsoon period compared to the Northwest (NW) monsoon and intermonsoon periods (approximately 2.5 times), which is probably related to seasonal variation of the abundance of Thaumarchaeota, or to enhanced export of GDGTs by aggregation with sinking phytoplankton detritus. Flux-weighted mean temperature inferred from the GDGT-based TEX86H index is 26.2 °C, which is 1.8 °C lower than mean annual (ma) SST but similar to SE monsoon SST. As the time series of TEX86H temperature estimates, however, does not record a strong seasonal amplitude, we infer that TEX86H reflects ma upper thermocline temperature at approximately 50 m water depth.

  16. Concentrations and solubility of trace elements in fine particles at a mountain site, southern China: regional sources and cloud processing

    Science.gov (United States)

    Li, T.; Wang, Y.; Li, W. J.; Chen, J. M.; Wang, T.; Wang, W. X.

    2015-08-01

    The concentrations and solubility of twelve trace elements in PM2.5 at Mt. Lushan, southern China, were investigated during the summer of 2011 and the spring of 2012. The average PM2.5 mass was 55.2 ± 20.1 μg m-3 during the observation period. Temporal variations of all trace elements including total and water-soluble fractions with several dust storm spikes in total fractions of Al and Fe were observed. The enrichment factor (EF) values were 1 order of magnitude higher for the water-soluble fractions versus the total fractions of trace elements. Four major emission sources, namely nonferrous metal mining and smelting (for Cr, As, Ba and parts of Zn), coal combustion (for Pb, Zn, Se, Cu and Mn), crustal materials (for Al and Fe) and municipal solid waste incineration (for Cd and Mo), were classified by principal component analysis (PCA). Trajectory cluster analysis and the potential source contribution function (PSCF) consistently identified the Yangtze River delta (YRD), the Pearl River delta (PRD), and the neighbouring provinces of Mt. Lushan as the major source regions and transport pathways for anthropogenic elements. Northern China was identified as a major source region for crustal elements. It should be noted that apart from the YRD, the area around Mt. Lushan has become the most significant contributor to the solubility of most trace elements. Element solubility can be partially determined by emission sources. However, enhanced solubility of trace elements corresponding to increased concentrations of sulfate after the occurrence of cloud events indicated significant effects of cloud processing on aerosol element dissolution. Metal particles mixed with sulfate in cloud droplet residues were further investigated through transmission electron microscopy (TEM) analysis. Irreversible alteration of particle morphology by cloud processing was confirmed to be highly responsible for the enhancement of trace element solubility. The findings from this study imply an

  17. A quasi-stationary approach to particle concentration and distribution in gear oil for wear mode estimation

    DEFF Research Database (Denmark)

    Henneberg, Morten; Eriksen, René Lynge; Jørgensen, Bent;

    2015-01-01

    that particles less than 14 μm dominate the wear. Hence, it is concluded that abrasion dominate the wear, for the gear in operation, and it is concluded to be in quasi-stationary mode. The distribution of the particles is observed in conjunction with the particle quantity to determine a basis for normal...

  18. Springtime carbon episodes at Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

    Directory of Open Access Journals (Sweden)

    J. Jung

    2011-05-01

    Full Text Available In order to investigate the carbon episodes at Gosan background super-site (33.17° N, 126.10° E in East Asia during spring of 2007 and 2008, total suspended particles (TSP were collected and analyzed for particulate organic carbon, elemental carbon, total carbon (TC, total nitrogen (TN, and stable carbon isotopic composition (δ13C of TC. The carbon episodes at the Gosan site were categorized as long-range transported anthropogenic pollutant (LTP from Asian continent, Asian dust (AD accompanying with LTP, and local pollen episodes. The stable carbon isotopic composition of TC (δ13CTC was found to be lowest during the pollen episodes (range: −26.2 ‰ to −23.5 ‰, avg.: −25.2 ± 0.9 ‰, followed by the LTP episodes (range: −23.5 ‰ to −23.0 ‰, avg.: −23.3 ± 0.3 ‰ and the AD episodes (range: −23.3 to −20.4 %, avg.: −21.8 ± 2.0 ‰. The δ13CTC of the airborne pollens (−28.0 ‰ collected at the Gosan site showed value similar to that of tangerine fruit (−28.1 ‰ produced from Jeju Island. Based on the carbon isotope mass balance equation and the TN and TC regression approach, we found that ∼40–45 % of TC in the TSP samples during the pollen episodes was attributed to airborne pollens from Japanese cedar trees planted around tangerine farms in Jeju Island. The δ13C of citric acid in the airborne pollens (−26.3 ‰ collected at the Gosan site was similar to that in tangerine fruit (−27.4 ‰. The negative correlation between the citric acid-carbon/TC ratios and δ13CTC were obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollens and then transported to the Gosan site. Based on the thermal evolution pattern of organic aerosols during the carbon episodes, we found that organic aerosols originated from East China are more volatile on

  19. Dispensing of high concentration Ag nano-particles ink for ultra-low resistivity paper-based writing electronics.

    Science.gov (United States)

    Wang, Fuliang; Mao, Peng; He, Hu

    2016-02-17

    Paper-based writing electronics has received a lot of interest recently due to its potential applications in flexible electronics. To obtain ultra-low resistivity paper-based writing electronics, we developed a kind of ink with high concentration of Ag Nano-particles (up to 80 wt%), as well as a related dispensing writing system consisting an air compressor machine and a dispenser. Additionally, we also demonstrated the writability and practical application of our proposed ink and writing system. Based on the study on the effect of sintering time and pressure, we found the optimal sintering time and pressure to obtain high quality Ag NPs wires. The electrical conductivity of nano-silver paper-based electronics has been tested using the calculated resistivity. After hot-pressure sintering at 120 °C, 25 MPa pressure for 20 minutes, the resistivity of silver NPs conductive tracks was 3.92 × 10(-8) (Ωm), only 2.45 times of bulk silver. The mechanical flexibility of nano-silver paper-based electronics also has been tested. After 1000 bending cycles, the resistivity slightly increased from the initial 4.01 × 10(-8) to 5.08 × 10(-8) (Ωm). With this proposed ink preparation and writing system, a kind of paper-based writing electronics with ultra-low resistivity and good mechanical flexibility was achieved.

  20. Impacts of biochar concentration and particle size on hydraulic conductivity and DOC leaching of biochar-sand mixtures

    Science.gov (United States)

    Liu, Zuolin; Dugan, Brandon; Masiello, Caroline A.; Barnes, Rebecca T.; Gallagher, Morgan E.; Gonnermann, Helge

    2016-02-01

    The amendment of soil with biochar can sequester carbon and alter hydrologic properties by changing physical and chemical characteristics of soil. To understand the effect of biochar amendment on soil hydrology, we measured the hydraulic conductivity (K) of biochar-sand mixtures as well as dissolved organic carbon (DOC) in leachate. Specifically, we assessed the effects of biochar concentration and particle size on K and amount of DOC in the soil leachate. To better understand how physical properties influenced K, we also measured the skeletal density of biochars and sand, and the bulk density, the water saturation, and the porosity of biochar-sand mixtures. Our model soil was sand (0.251-0.853 mm) with biochar rates from 2 to 10 wt% (g biochar/g total soil × 100%). As biochar (experiments suggest that mixing sandy soils with biochar is likely to reduce infiltration rates, holding water near the surface longer with little loss of biochar-derived carbon to groundwater and streams.

  1. Dispensing of high concentration Ag nano-particles ink for ultra-low resistivity paper-based writing electronics

    Science.gov (United States)

    Wang, Fuliang; Mao, Peng; He, Hu

    2016-02-01

    Paper-based writing electronics has received a lot of interest recently due to its potential applications in flexible electronics. To obtain ultra-low resistivity paper-based writing electronics, we developed a kind of ink with high concentration of Ag Nano-particles (up to 80 wt%), as well as a related dispensing writing system consisting an air compressor machine and a dispenser. Additionally, we also demonstrated the writability and practical application of our proposed ink and writing system. Based on the study on the effect of sintering time and pressure, we found the optimal sintering time and pressure to obtain high quality Ag NPs wires. The electrical conductivity of nano-silver paper-based electronics has been tested using the calculated resistivity. After hot-pressure sintering at 120 °C, 25 MPa pressure for 20 minutes, the resistivity of silver NPs conductive tracks was 3.92 × 10-8 (Ωm), only 2.45 times of bulk silver. The mechanical flexibility of nano-silver paper-based electronics also has been tested. After 1000 bending cycles, the resistivity slightly increased from the initial 4.01 × 10-8 to 5.08 × 10-8 (Ωm). With this proposed ink preparation and writing system, a kind of paper-based writing electronics with ultra-low resistivity and good mechanical flexibility was achieved.

  2. Concentration and composition of dust particles in surface snow at Urumqi Glacier No. 1, Eastern Tien Shan

    Science.gov (United States)

    Wu, Guangjian; Zhang, Xuelei; Zhang, Chenglong; Gao, Shaopeng; Li, Zhongqin; Wang, Feiteng; Wang, Wenbin

    2010-10-01

    Major, trace, and rare earth elements (REE) were determined by inductively coupled plasma-mass spectrometer (ICP-MS) for dust particles that were extracted from fresh surface snow samples collected weekly or biweekly between March 2006 and January 2008 at Urumqi Glacier No. 1 (UG1) in Eastern Tien Shan, Central Asia. The UG1 dust shows average Fe/Al ratios of 0.7, Ca/Al ratios of 0.35, La/Th ratios of 2.62, Th/U ratios of 3.31, an Eu anomaly of 0.63, and L/HREE ratios of 7.87. Seasonal variation is significant in dust concentration, but is not observed in dust composition, which remains rather uniform throughout the sampling period. The compositional homogeneity suggests that dust materials in UG1 are well mixed from their possible source areas. Fine materials from the Junggar Basin, and to a less extend from Tarim Basin, more closely resemble UG1 dust properties in their REE composition than do the local moraines, indicating that the dust in UG1 snow mainly comes from mid- to long-range source areas. The HYSPLIT model results suggest that the Westerlies, Arctic air masses and local winds are the main circulations for dust transport to Eastern Tien Shan.

  3. Dense suspension of solid particles as a new heat transfer fluid for concentrated solar thermal plants: on-sun proof of concept

    OpenAIRE

    Flamant, Gilles; Gauthier, Daniel; Benoit, Hadrien; Sans, Jean-Louis; Garcia, Roger; Boissière, Benjamin; Ansart, Renaud; Hemati, Mehrdji

    2013-01-01

    This paper demonstrates the capacity of dense suspensions of solid particles to transfer concentrated solar power from a tubular receiver to an energy conversion process by acting as a heat transfer fluid. Contrary to a circulating fluidized bed, the dense suspension of particles' flows operates at low gas velocity and large solid fraction. A single-tube solar receiver was tested with 64 µm mean diameter silicon carbide particles for solar flux densities in the range 200-250 kW/m2, resulting ...

  4. An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors

    Directory of Open Access Journals (Sweden)

    Jian Li

    2015-12-01

    Full Text Available The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within −3%–8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

  5. An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors.

    Science.gov (United States)

    Li, Jian; Kong, Ming; Xu, Chuanlong; Wang, Shimin; Fan, Ying

    2015-12-10

    The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within -3%-8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

  6. Transport and deposition of polymer-modified Fe0 nanoparticles in 2-D heterogeneous porous media: effects of particle concentration, Fe0 content, and coatings.

    Science.gov (United States)

    Phenrat, Tanapon; Cihan, Abdullah; Kim, Hye-Jin; Mital, Menka; Illangasekare, Tissa; Lowry, Gregory V

    2010-12-01

    Concentrated suspensions of polymer-modified Fe(0) nanoparticles (NZVI) are injected into heterogeneous porous media for groundwater remediation. This study evaluated the effect of porous media heterogeneity and the dispersion properties including particle concentration, Fe(0) content, and adsorbed polymer mass and layer thickness which are expected to affect the delivery and emplacement of NZVI in heterogeneous porous media in a two-dimensional (2-D) cell. Heterogeneity in hydraulic conductivity had a significant impact on the deposition of NZVI. Polymer modified NZVI followed preferential flow paths and deposited in the regions where fluid shear is insufficient to prevent NZVI agglomeration and deposition. NZVI transported in heterogeneous porous media better at low particle concentration (0.3 g/L) than at high particle concentrations (3 and 6 g/L) due to greater particle agglomeration at high concentration. High Fe(0) content decreased transport during injection due to agglomeration promoted by magnetic attraction. NZVI with a flat adsorbed polymeric layer (thickness ∼30 nm) could not be transported effectively due to pore clogging and deposition near the inlet, while NZVI with a more extended adsorbed layer thickness (i.e., ∼70 nm) were mobile in porous media. This study indicates the importance of characterizing porous media heterogeneity and NZVI dispersion properties as part of the design of a robust delivery strategy for NZVI in the subsurface. PMID:21058703

  7. Background Material

    DEFF Research Database (Denmark)

    Zandersen, Marianne; Hyytiäinen, Kari; Saraiva, Sofia;

    2016-01-01

    This document serves as a background material to the BONUS Pilot Scenario Workshop, which aims to develop harmonised regional storylines of socio-ecological futures in the Baltic Sea region in a collaborative effort together with other BONUS projects and stakeholders.......This document serves as a background material to the BONUS Pilot Scenario Workshop, which aims to develop harmonised regional storylines of socio-ecological futures in the Baltic Sea region in a collaborative effort together with other BONUS projects and stakeholders....

  8. A high gradient and strength bioseparator with nano-sized immunomagnetic particles for specific separation and efficient concentration of E. coli O157:H7

    International Nuclear Information System (INIS)

    Sample pretreatment is a key to rapid screening of pathogens for prevention and control of foodborne diseases. Magnetic immunoseparation is a specific method based on antibody–antigen reaction to capture the target bacteria and concentrate them in a smaller-volume buffer. The use of nano-sized magnetic particles could improve the separation efficiency of bacteria but require much higher gradient and strength magnetic field. In this study, a strong magnetic bioseparator with a mean field strength of 1.35 T and a mean gradient of 90 T/m was developed with the use of the 30 nm and 180 nm magnetic particles to specifically separate and efficiently concentrate foodborne bacterial pathogens using Escherichia coli O157:H7 as a model bacterium. The polyclonal antibodies against E. coli were evaluated using Dot ELISA analysis for their good affinity with the target bacteria and then used to modify the surface of the magnetic nanoparticles by 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) method and streptavidin-biotin binding. The magnetic particle concentrations were optimized to be 40 µg/ml and 100 µg/ml for the 30 nm and 180 nm particles, respectively, the immunoreaction time was optimized to be 45 min for both sizes of particles, and the separation times were optimized to be 60 min and 2 min for the 30 nm and 180 nm particles, respectively. The total magnetic separation time was 2 h and 1 h for the 30 nm and 180 nm particles, respectively. The experimental results demonstrated that the bioseparator with the use of either 30 nm or 180 nm immunomagnetic particles could achieve a separation efficiency of >90% for E. coli O157:H7 at the concentrations ranging from 102 to 105 cfu/ml. No obvious interferences from non-target foodborne pathogens, such as SalmonellaTyphimurium and Listeria innocua, were found. For overall consideration of the consuming time, the cost, and the separation efficiency, the 180 nm magnetic particles are practical for

  9. A high gradient and strength bioseparator with nano-sized immunomagnetic particles for specific separation and efficient concentration of E. coli O157:H7

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jianhan, E-mail: jianhan@cau.edu.cn [Ministry of Agriculture Key Laboratory of Agricultural Information Acquisition Technology (Beijing), 17 East Tsinghua Road, China Agricultural University, Mailbox 125, Beijing 100083 (China); Li, Min [College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058 (China); Li, Yanbin [College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058 (China); Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Chen, Qi [Modern Precision Agriculture System Integration Research Key Laboratory of Ministry of Education, China Agricultural University, Beijing 100083 (China)

    2015-03-15

    Sample pretreatment is a key to rapid screening of pathogens for prevention and control of foodborne diseases. Magnetic immunoseparation is a specific method based on antibody–antigen reaction to capture the target bacteria and concentrate them in a smaller-volume buffer. The use of nano-sized magnetic particles could improve the separation efficiency of bacteria but require much higher gradient and strength magnetic field. In this study, a strong magnetic bioseparator with a mean field strength of 1.35 T and a mean gradient of 90 T/m was developed with the use of the 30 nm and 180 nm magnetic particles to specifically separate and efficiently concentrate foodborne bacterial pathogens using Escherichia coli O157:H7 as a model bacterium. The polyclonal antibodies against E. coli were evaluated using Dot ELISA analysis for their good affinity with the target bacteria and then used to modify the surface of the magnetic nanoparticles by 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) method and streptavidin-biotin binding. The magnetic particle concentrations were optimized to be 40 µg/ml and 100 µg/ml for the 30 nm and 180 nm particles, respectively, the immunoreaction time was optimized to be 45 min for both sizes of particles, and the separation times were optimized to be 60 min and 2 min for the 30 nm and 180 nm particles, respectively. The total magnetic separation time was 2 h and 1 h for the 30 nm and 180 nm particles, respectively. The experimental results demonstrated that the bioseparator with the use of either 30 nm or 180 nm immunomagnetic particles could achieve a separation efficiency of >90% for E. coli O157:H7 at the concentrations ranging from 10{sup 2} to 10{sup 5} cfu/ml. No obvious interferences from non-target foodborne pathogens, such as SalmonellaTyphimurium and Listeria innocua, were found. For overall consideration of the consuming time, the cost, and the separation efficiency, the 180 nm magnetic particles are

  10. Direct observation of solid-phase adsorbate concentration profile in powdered activated carbon particle to elucidate mechanism of high adsorption capacity on super-powdered activated carbon.

    Science.gov (United States)

    Ando, Naoya; Matsui, Yoshihiko; Matsushita, Taku; Ohno, Koichi

    2011-01-01

    Decreasing the particle size of powdered activated carbon (PAC) by pulverization increases its adsorption capacities for natural organic matter (NOM) and polystyrene sulfonate (PSS, which is used as a model adsorbate). A shell adsorption mechanism in which NOM and PSS molecules do not completely penetrate the adsorbent particle and instead preferentially adsorb near the outer surface of the particle has been proposed as an explanation for this adsorption capacity increase. In this report, we present direct evidence to support the shell adsorption mechanism. PAC particles containing adsorbed PSS were sectioned with a focused ion beam, and the solid-phase PSS concentration profiles of the particle cross-sections were directly observed by means of field emission-scanning electron microscopy/energy-dispersive X-ray spectrometry (FE-SEM/EDXS). X-ray emission from sulfur, an index of PSS concentration, was higher in the shell region than in the inner region of the particles. The X-ray emission profile observed by EDXS did not agree completely with the solid-phase PSS concentration profile predicted by shell adsorption model analysis of the PSS isotherm data, but the observed and predicted profiles were not inconsistent when the analytical errors were considered. These EDXS results provide the first direct evidence that PSS is adsorbed mainly in the vicinity of the external surface of the PAC particles, and thus the results support the proposition that the increase in NOM and PSS adsorption capacity with decreasing particle size is due to the increase in external surface area on which the molecules can be adsorbed. PMID:20851447

  11. Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site during SAPUSS -diurnal variations and PMF receptor modelling

    NARCIS (Netherlands)

    Dall'Osto, M.; Querol, X.; Amato, F.; Karanasiou, A.; Lucarelli, F.; Nava, S.; Calzolai, G.; Chiari, M.

    2013-01-01

    Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb) were obtained by time

  12. A multi-site analysis of the association between black carbon concentrations and vehicular idling, traffic, background pollution, and meteorology during school dismissals.

    Science.gov (United States)

    Richmond-Bryant, J; Bukiewicz, L; Kalin, R; Galarraga, C; Mirer, F

    2011-05-01

    A study was performed to assess the relationship between black carbon (BC), passing traffic, and vehicular idling outside New York City (NYC) schools during student dismissal. Monitoring was performed at three school sites in East Harlem, the Bronx, and Brooklyn for 1month per year over a two-year period from November 2006-October 2008. Monitoring at each site was conducted before and after the Asthma Free School Zone (AFSZ) asthma reduction education program was administered. Real-time equipment with a one-minute averaging interval was used to obtain the BC data, while volume counts of idling and passing school busses, trucks, and automobiles were collected each minute by study staff. These data were matched to ambient PM(2.5) and meteorology data obtained from the New York State Department of Environmental Conservation. A generalized additive model (GAM) model was run to examine the relationship between BC concentration and each variable while accounting for site-to-site differences. F-tests were employed to assess the significance of each of the predictor variables. The model results suggested that variability in ambient PM(2.5) concentration contributed 24% of the variability in transformed BC concentration, while variability in the number of idling busses and trucks on the street during dismissal contributed 20% of the variability in transformed BC concentration. The results of this study suggest that a combination of urban scale and local traffic control approaches in combination with cessation of school bus idling will produce improved local BC concentration outside schools.

  13. A multi-site analysis of the association between black carbon concentrations and vehicular idling, traffic, background pollution, and meteorology during school dismissals.

    Science.gov (United States)

    Richmond-Bryant, J; Bukiewicz, L; Kalin, R; Galarraga, C; Mirer, F

    2011-05-01

    A study was performed to assess the relationship between black carbon (BC), passing traffic, and vehicular idling outside New York City (NYC) schools during student dismissal. Monitoring was performed at three school sites in East Harlem, the Bronx, and Brooklyn for 1month per year over a two-year period from November 2006-October 2008. Monitoring at each site was conducted before and after the Asthma Free School Zone (AFSZ) asthma reduction education program was administered. Real-time equipment with a one-minute averaging interval was used to obtain the BC data, while volume counts of idling and passing school busses, trucks, and automobiles were collected each minute by study staff. These data were matched to ambient PM(2.5) and meteorology data obtained from the New York State Department of Environmental Conservation. A generalized additive model (GAM) model was run to examine the relationship between BC concentration and each variable while accounting for site-to-site differences. F-tests were employed to assess the significance of each of the predictor variables. The model results suggested that variability in ambient PM(2.5) concentration contributed 24% of the variability in transformed BC concentration, while variability in the number of idling busses and trucks on the street during dismissal contributed 20% of the variability in transformed BC concentration. The results of this study suggest that a combination of urban scale and local traffic control approaches in combination with cessation of school bus idling will produce improved local BC concentration outside schools. PMID:21406309

  14. Concentrations and solubility of trace elements in fine particles at a mountain site, southern China: regional sources and cloud processing

    Directory of Open Access Journals (Sweden)

    T. Li

    2015-05-01

    Full Text Available The concentrations and solubility of twelve trace elements in PM2.5 at Mt. Lushan, southern China, were investigated during the summer of 2011 and the spring of 2012. The average PM2.5 mass was 55.2 ± 20.1 μg m-3 during the observation period. Temporal variations of all trace elements including total and water-soluble fractions with several dust storm spikes for total fraction Al and Fe were observed. The enrichment factor (EF values were one order of magnitude higher for the water-soluble fractions vs. the total fractions of trace elements. Four major emission sources were classified by principal component analysis (PCA, namely nonferrous metal mining and smelting (for Cr, As, Ba and parts of Zn, coal combustion (for Pb, Zn, Se, Cu and Mn, crustal materials (for Al and Fe and municipal solid waste incineration (for Cd and Mo. Trajectory cluster analysis and the potential source contribution function (PSCF consistently identified the Yangtze River Delta (YRD, the Pearl River Delta (PRD and parts of Hunan and Jiangxi as the major source regions and pathways for anthropogenic elements, while northern China was identified for crustal elements. In contrast, the local Jiangxi area has become the most significant contributor to the solubility of most trace elements, apart from the YRD with severe air pollution. In addition, the solubility alteration of trace elements in cloud events was investigated and transmission electron microscopy (TEM analysis indicated that the irreversible alteration of particle morphology by cloud processing was highly responsible for the enhancement of element solubility. Our work implies an important role of regional anthropogenic pollution and cloud processing in the evolution of trace element solubility during transport.

  15. Understanding improved dissolution of indomethacin through the use of cohesive poorly water-soluble aluminium hydroxide: effects of concentration and particle size distribution.

    Science.gov (United States)

    Tay, Tracy; Allahham, Ayman; Morton, David A V; Stewart, Peter J

    2011-10-01

    The objective of this study was to explore the effects of concentration and particle size distribution of an added poorly water-soluble inorganic salt, aluminium hydroxide, on the dissolution of a poorly water-soluble drug, indomethacin (IMC), from lactose interactive mixtures. Dissolution was studied using the United States Pharmacopeia paddle method in buffer pH 5.0 and the data most aptly fitted a bi-exponential dissolution model which represented dissolution occurring from dispersed and agglomerated particles. The dispersion of IMC mixtures was measured in dissolution media under non-sink conditions by laser diffraction. The dissolution of IMC increased as a function of the concentration of aluminium hydroxide (5-20%) added to the mixtures. Increasing the proportion of larger particles of the cohesive aluminium hydroxide increased the dissolution rate of IMC. The enhanced dissolution was attributed to increases in both the dissolution rate constant and initial concentration of dispersed particles. Mechanistically, the aluminium hydroxide was found to facilitate the detachment of IMC particles from the carrier surface, forming a complex interactive mixture that more readily deagglomerated than the cohesive drug agglomerates. The outcomes of this work would therefore allow more careful control and selection of the excipient specifications in producing solid dosage formulations with improved dissolution of poorly water-soluble drugs. PMID:21560127

  16. Model of a black hole gas submitted to background gravitational field for active galaxy nuclei with application to calculating the continuous emission spectra of massless particles (Photons: neutrinos and gravitons)

    International Nuclear Information System (INIS)

    A new theoretical model for active galaxy nuclei which describes the continuous spectrum of rest massless particles (photons, neutrinos and gravitons) in the frequency range from radiofrequency to gamma ray frequency, is presented. The model consists in a black hole gas interacting with a background gravitacional field. The previously models proposed for active galaxy nuclei are exposured. Whole theoretical fundaments based on Einstein general relativity theory for defining and studying singularity properties (black holes) are also presented. (M.C.K.)

  17. A high gradient and strength bioseparator with nano-sized immunomagnetic particles for specific separation and efficient concentration of E. coli O157:H7

    Science.gov (United States)

    Lin, Jianhan; Li, Min; Li, Yanbin; Chen, Qi

    2015-03-01

    Sample pretreatment is a key to rapid screening of pathogens for prevention and control of foodborne diseases. Magnetic immunoseparation is a specific method based on antibody-antigen reaction to capture the target bacteria and concentrate them in a smaller-volume buffer. The use of nano-sized magnetic particles could improve the separation efficiency of bacteria but require much higher gradient and strength magnetic field. In this study, a strong magnetic bioseparator with a mean field strength of 1.35 T and a mean gradient of 90 T/m was developed with the use of the 30 nm and 180 nm magnetic particles to specifically separate and efficiently concentrate foodborne bacterial pathogens using Escherichia coli O157:H7 as a model bacterium. The polyclonal antibodies against E. coli were evaluated using Dot ELISA analysis for their good affinity with the target bacteria and then used to modify the surface of the magnetic nanoparticles by 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) method and streptavidin-biotin binding. The magnetic particle concentrations were optimized to be 40 μg/ml and 100 μg/ml for the 30 nm and 180 nm particles, respectively, the immunoreaction time was optimized to be 45 min for both sizes of particles, and the separation times were optimized to be 60 min and 2 min for the 30 nm and 180 nm particles, respectively. The total magnetic separation time was 2 h and 1 h for the 30 nm and 180 nm particles, respectively. The experimental results demonstrated that the bioseparator with the use of either 30 nm or 180 nm immunomagnetic particles could achieve a separation efficiency of >90% for E. coli O157:H7 at the concentrations ranging from 102 to 105 cfu/ml. No obvious interferences from non-target foodborne pathogens, such as SalmonellaTyphimurium and Listeria innocua, were found. For overall consideration of the consuming time, the cost, and the separation efficiency, the 180 nm magnetic particles are practical for rapid

  18. Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media.

    Science.gov (United States)

    Strutz, Tessa J; Hornbruch, Götz; Dahmke, Andreas; Köber, Ralf

    2016-08-01

    Successful groundwater remediation by injecting nanoscale zero-valent iron (NZVI) particles requires efficient particle transportation and distribution in the subsurface. This study focused on the influence of injection velocity and particle concentration on the spatial NZVI particle distribution, the deposition processes and on quantifying the induced decrease in hydraulic conductivity (K) as a result of particle retention by lab tests and numerical simulations. Horizontal column tests of 2m length were performed with initial Darcy injection velocities (q0) of 0.5, 1.5, and 4.1m/h and elemental iron input concentrations (Fe(0)in) of 0.6, 10, and 17g/L. Concentrations of Fe(0) in the sand were determined by magnetic susceptibility scans, which provide detailed Fe(0) distribution profiles along the column. NZVI particles were transported farther at higher injection velocity and higher input concentrations. K decreased by one order of magnitude during injection in all experiments, with a stronger decrease after reaching Fe(0) concentrations of about 14-18g/kg(sand). To simulate the observed nanoparticle transport behavior the existing finite-element code OGS has been successfully extended and parameterized for the investigated experiments using blocking, ripening, and straining as governing deposition processes. Considering parameter relationships deduced from single simulations for each experiment (e.g. deposition rate constants as a function of flow velocity) one mean parameter set has been generated reproducing the observations in an adequate way for most cases of the investigated realistic injection conditions. An assessment of the deposition processes related to clogging effects showed that the percentage of retention due to straining and ripening increased during experimental run time resulting in an ongoing reduction of K. Clogging is mainly evoked by straining which dominates particle deposition at higher flow velocities, while blocking and ripening play a

  19. Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media

    Science.gov (United States)

    Strutz, Tessa J.; Hornbruch, Götz; Dahmke, Andreas; Köber, Ralf

    2016-08-01

    Successful groundwater remediation by injecting nanoscale zero-valent iron (NZVI) particles requires efficient particle transportation and distribution in the subsurface. This study focused on the influence of injection velocity and particle concentration on the spatial NZVI particle distribution, the deposition processes and on quantifying the induced decrease in hydraulic conductivity (K) as a result of particle retention by lab tests and numerical simulations. Horizontal column tests of 2 m length were performed with initial Darcy injection velocities (q0) of 0.5, 1.5, and 4.1 m/h and elemental iron input concentrations (Fe0in) of 0.6, 10, and 17 g/L. Concentrations of Fe0 in the sand were determined by magnetic susceptibility scans, which provide detailed Fe0 distribution profiles along the column. NZVI particles were transported farther at higher injection velocity and higher input concentrations. K decreased by one order of magnitude during injection in all experiments, with a stronger decrease after reaching Fe0 concentrations of about 14-18 g/kg(sand). To simulate the observed nanoparticle transport behavior the existing finite-element code OGS has been successfully extended and parameterized for the investigated experiments using blocking, ripening, and straining as governing deposition processes. Considering parameter relationships deduced from single simulations for each experiment (e.g. deposition rate constants as a function of flow velocity) one mean parameter set has been generated reproducing the observations in an adequate way for most cases of the investigated realistic injection conditions. An assessment of the deposition processes related to clogging effects showed that the percentage of retention due to straining and ripening increased during experimental run time resulting in an ongoing reduction of K. Clogging is mainly evoked by straining which dominates particle deposition at higher flow velocities, while blocking and ripening play a

  20. Statistical modelling of particle number concentration in Zurich at high spatio-temporal resolution utilizing data from a mobile sensor network

    Science.gov (United States)

    Mueller, M. D.; Hasenfratz, David; Saukh, Olga; Fierz, Martin; Hueglin, Christoph

    2016-02-01

    Highly resolved pollution maps are a valuable resource for many issues related to air quality including exposure modelling and urban planning. We present an approach for their generation based on data from a mobile sensor network and statistical modelling. An extensive record of particle number concentrations (PNCs) spanning more than 1.5 years was compiled by the tram-based OpenSense mobile sensor network in the City of Zurich. The sensor network consists of 10 sensor nodes installed on the roof of trams operating on different services according to their regular operation schedules. We developed a statistical modelling approach based on Generalized Additive models (GAMs) utilizing the PNC data obtained along the tram tracks as well as georeferenced information as predictor variables. Our approach includes a variable selection algorithm to ensure that individual models rely on the optimal set of predictor variables. Our models have high temporal and spatial resolutions of 30 min and 10 m by 10 m, respectively, and allow the spatial prediction of PNC in the municipal area of Zurich. We applied our approach to PNC data from two dedicated time periods: July-Sept. 2013 and Dec. 2013-Feb. 2014. The models strongly rely on traffic related predictor variables (vehicle counts) and, due to the hilly topography of Zurich, on elevation. We assessed the model performance by leave-one-out cross-validation and by comparing PNC predictions to measurements at fixed reference sites and to PNC measurements obtained by pedestrians. Model predictions reproduce well the main features of the PNC field in environment types similar to those passed by individual trams. Model performance is worse at elevated background locations probably due to the weak coverage of similar spots by the tram network. We end the paper by outlining a route finding algorithm which utilizes the highly resolved PNC maps providing the exposure minimal route for cyclists.

  1. The challenge of measuring sulfuric acid aerosols: number concentration and size evaluation using a condensation particle counter (CPC) and an electrical low pressure impactor (ELPI+)

    NARCIS (Netherlands)

    Brachert, L.; Mertens, J.; Khakharia, P.M.; Schaber, K.

    2014-01-01

    In this study, two different methods for the measurement of the sulfuric acid aerosol which is formed in wet flue gas cleaning processes have been investigated. The condensation particle counter (UFCPC, PALAS GmbH) provides information about the number concentration. With the electrical low pressure

  2. Fasting and postprandial remnant-like particle cholesterol concentrations in obese participants are associated with plasma triglycerides, insulin resistance, and body fat distribution

    DEFF Research Database (Denmark)

    van Hees, Anneke M. J.; Saris, Wim H. M.; Dallinga-Thie, Geesje M.;

    2008-01-01

    Elevated plasma concentrations of remnant-like particle cholesterol (RLP-C) are atherogenic. However, factors that determine RLP-C are not fully understood. This study evaluates which factors affect RLP-C in the fasting and postprandial state, using multiple regression analyses in a large cohort...

  3. Local microwave background radiation

    OpenAIRE

    Soares, Domingos

    2006-01-01

    An inquiry on a possible local origin for the Microwave Background Radiation is made. Thermal MBR photons are contained in a system called {\\it magnetic bottle} which is due to Earth magnetic field and solar wind particles, mostly electrons. Observational tests are anticipated.

  4. Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site during SAPUSS – diurnal variations and PMF receptor modelling

    Directory of Open Access Journals (Sweden)

    M. Dall'Osto

    2013-04-01

    Full Text Available Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb were obtained by time (1 h and size (PM2.5 particulate matter 2.5 mass fraction simultaneously measured at the UB and RS sites: (1 the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2 by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3 a unique source of Pb-Cl (associated with combustion emissions is found to be the major (82% source of fine Cl in the urban agglomerate; (4 the mean diurnal variation of PM2.5 primary traffic non-exhaust brake dust (Fe-Cu suggests that this source is mainly emitted and not resuspended, whereas PM2.5 urban dust (Ca is found mainly resuspended by both traffic vortex and sea breeze; (5 urban dust (Ca is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing urban dust concentrations.

  5. Effect of particle size and concentration on the mechanical properties of polyester/date palm seed particulate composites

    Directory of Open Access Journals (Sweden)

    Alewo Opuada AMEH

    2015-05-01

    Full Text Available The use of cellulosic materials as reinforcement in composites can greatly enhance their properties. The thrust of this study was to investigate the effect of date palm seed particle on the properties of reinforced polyester. Unsaturated polyester resin was reinforced with date palm seed particles of 0.5, 2.0 and 2.8mm particle sizes using variable particle loadings of 5, 10, 15, 20 and 25wt%. The composites obtained were subjected to various types of mechanical and physical tests in order to assess their performance. The optimum tensile strength of 16.7619N/mm2 and elastic modulus of 343.8N/mm2 were attained at 15wt% and 10wt% loading (using 0.5mm particles respectively and percent water absorption was found to be least for 0.5mm particle size. The hardness was enhanced to the maximum of 74 HRF (Rockwell Hardness Factor by 2mm particle size at 25wt% loading. Pure unsaturated polyester resin recorded tensile strength of 17.5959N/mm2, elastic modulus of 316.7N/mm2 and hardness of 33.5 HRF. The results indicated that the use of date palm seed particles as reinforcement can enhance the properties of polyester composites.

  6. Activity concentrations of 226Ra, 228Th, and 40K in different food crops from a high background radiation area in Bitsichi, Jos Plateau, Nigeria.

    Science.gov (United States)

    Jibiri, N N; Farai, I P; Alausa, S K

    2007-03-01

    One of the three goals of the United Nations for sustainable food security is to ensure that all people have access to sufficient, nutritionally adequate, and safe food. Decades of tin mining in the Bitsichi area of the Jos Plateau, Nigeria, have left a legacy of polluted water supplies, impoverished agricultural land, and soil containing abnormally high levels of naturally occurring radioactive elements. In order to ascertain the radiological food safety of the population, different crops that constitute the major food nutritive requirements were collected directly across farmlands in the area. The activity concentrations of (226)Ra, (228)Th, and (40)K were determined in the food and soil samples using gamma-ray spectrometry. Additionally, in situ gamma dose rate measurements were performed on the farms using a pre-calibrated survey meter. The corresponding activity concentrations in the food crops ranged from below detection limit (BDL) to 684.5 Bq kg(-1) for (40)K, from BDL to 83.5 Bq kg(-1) for (226)Ra, and from BDL to 89.8 Bq kg(-1) for (228)Th. Activity concentrations of these radionuclides were found to be lower in cereals than in tubers and vegetables. As for the soil samples, activity concentrations of these radionuclides varied from BDL to 166.4 Bq kg(-1), from 10.9 to 470.6 Bq kg(-1), and from 122.7 to 2,189.5 Bq kg(-1) for (40)K, (226)Ra, and (228)Th, respectively. Average external gamma dose rates were found to vary across the farms from 0.50 +/- 0.01 to 1.47 +/- 0.04 microSv h(-1). Due to past mining activities, the soil radioactivity in the area has been modified and the concentration level of the investigated natural radionuclides in the food crops has also been enhanced. However, the values obtained suggest that the dose from intake of these radionuclides by the food crops is low and that harmful health effects are not expected. PMID:17211656

  7. Occurrence of gaseous and particulate polycyclic aromatic hydrocarbons in the urban atmosphere: study of sources and ambient temperature effect on the gas/particle concentration and distribution

    Energy Technology Data Exchange (ETDEWEB)

    Tsapakis, Manolis [Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, EL-71409 Heraklion (Greece); Stephanou, Euripides G. [Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, EL-71409 Heraklion (Greece)]. E-mail: stephanou@chemistry.uoc.gr

    2005-01-01

    The presence of polycyclic aromatic hydrocarbons (PAHs) in an urban region (Heraklion, Greece) and processes that govern their atmospheric fate were studied from November 2000 until February 2002. Sixteen samples were collected, by using an artifact-free sampling device, on a monthly basis and the concentration of PAHs in gas and particulate phase was determined. The most abundant members (gas + particles) were phenanthrene (20.0 {+-} 7.0 ng m{sup -3}), fluoranthene (6.5 {+-} 1.7 ng m{sup -3}), pyrene (6.6 {+-} 2.4 ng m{sup -3}), and chrysene (3.1 {+-} 1.5 ng m{sup -3}). Total concentration (gas + particulate) of PAH ranged from 44.3 to 129.2 ng m{sup -3}, with a mean concentration of 79.3 ng m{sup -3}. Total concentration of PAHs in gas phase ranged from 31.4 to 84.7 ng m{sup -3} with non-observable seasonal variation. Conversely, maximum PAH concentrations in the particulate phase occurred during winter months. Particulate concentration varied from 11.4 to 44.9 ng m{sup -3}, with an average of 25.2 ng m{sup -3}. PAH distribution between gas and particulate phase was in agreement with the sub-cooled vapor pressure. Shift in gas/particle distribution due to difference in ambient temperature elucidated to some extent the seasonal variation of the concentration of PAHs in particles. - Capsule: Ambient PAH partitioning between gas and particle phases vary between compounds and with environmental conditions.

  8. Effect of particle concentration on the structure and tribological properties of submicron particle SiC reinforced Ni metal matrix composite (MMC) coatings produced by electrodeposition

    Science.gov (United States)

    Gül, H.; Kılıç, F.; Uysal, M.; Aslan, S.; Alp, A.; Akbulut, H.

    2012-03-01

    In the present work, a nickel sulfate bath containing SiC submicron particles between 100 and 1000 nm was used as the plating electrolyte. The aim of this work is to obtain Ni-SiC metal matrix composites (MMCs) reinforced with submicron particles on steel surfaces with high hardness and wear resistance for using in anti-wear applications such as dies, tools and working parts for automobiles and vehicles. The influence of the SiC content in the electrolyte on particle distribution, microhardness and wear resistance of nano-composite coatings was studied. During the electroplating process, the proper stirring speed was also determined for sub-micron SiC deposition with Ni matrix. The Ni films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The depositions were controlled to obtain a specific thickness (between 50 and 200 μm) and volume fraction of the particles in the matrix (between 0.02 and 0.10). The hardness of the coatings was measured to be 280-571 HV depending on the particle volume in the Ni matrix. The tribological behaviors of the electrodeposited SiC nanocomposite coatings sliding against an M50 steel ball (Ø 10 mm) were examined on a tribometer. All the friction and wear tests were performed without lubrication at room temperature and in the ambient air (with a relative humidity of 55-65%). The results showed that the wear resistance of the nanocomposites was approximately 2-2.2 times more than those of unreinforced Ni.

  9. Magnetic particle imaging an introduction to imaging principles and scanner instrumentation

    CERN Document Server

    Knopp, Tobias

    2012-01-01

    This is an overview of recent progress in magnetic particle imaging, which uses various static and oscillating magnetic fields and tracer materials made from iron oxide nanoparticles to perform background-free measurements of the particles' local concentration.

  10. Particle size distributions, size concentration relationships, and adherence to hands of selected geologic media derived from mining, smelting, and quarrying activities

    Energy Technology Data Exchange (ETDEWEB)

    Bergstrom, Carolyn; Shirai, Jeffry; Kissel, John, E-mail: jkissel@uw.edu

    2011-09-15

    Hand-to-mouth activity, especially in children, is a potentially significant pathway of exposure to soil contaminants. Hand-mouthing behavior is of particular concern in areas impacted by mining, smelting, and quarrying activities as these activities may lead to elevated levels of heavy metals in soil. In order to estimate potential exposures to contaminated geologic media attributable to hand-to-mouth contact, it is useful to characterize adherence of those media to skin, as contaminant concentrations in adhered media may differ greatly from unfractionated, whole media concentrations. Such an investigation has been undertaken to aid estimation of exposures to arsenic, cadmium, lead, and zinc in nine different geologic media collected in the Pacific Northwest region of the United States. After establishing the particle size distribution of each medium (fractions < 63 {mu}m, 63-150 {mu}m, 150-250 {mu}m, and 250 {mu}m-2 mm were determined) and target elemental concentrations within each particle size fraction, an active handling protocol involving six volunteers was conducted. Wet media always adhered to a greater extent than dry media and adhered media generally had higher elemental concentrations than bulk media. Regression analyses suggest smaller particle fractions may have higher elemental concentrations. Results of application of a maximum likelihood estimation technique generally indicate that handling of dry media leads to preferential adherence of smaller particle sizes, while handling of wet media does not. Because adhered material can differ greatly in particle size distribution from that found in bulk material, use of bulk concentrations in exposure calculations may lead to poor estimation of actual exposures. Since lead has historically been a metal of particular concern, EPA's Integrated Exposure Uptake Biokinetic (IEUBK) Model was used to examine the potential consequences of evaluating ingestion of the selected media assuming concentrations in

  11. Near-bottom suspended matter concentration on the Continental Shelf during storms: estimates based on in situ observations of light transmission and a particle size dependent transmissometer calibration

    Science.gov (United States)

    Moody, J.A.; Butman, B.; Bothner, Michael H.

    1987-01-01

    A laboratory calibration of Sea Tech and Montedoro-Whitney beam transmissometers shows a linear relation between light attenuation coefficient (cp) and suspended matter concentration (SMC) for natural sediments and for glass beads. However the proportionality constant between cp and SMC depends on the particle diameter and particle type. Thus, to measure SMC, observations of light attenuation must be used with a time-variable calibration when suspended particle characteristics change with time. Because of this variable calibration, time series of light attenuation alone may not directly reflect SMC and must be interpreted with care. The near-bottom concentration of suspended matter during winter storms on the U.S. East Coast Continental Shelf is estimated from light transmission measurements made 2 m above the bottom and from the size distribution of suspended material collected simultaneously in sediment traps 3 m above the bottom. The average concentrations during six storms between December 1979 and February 1980 in the Middle Atlantic Bight ranged from 2 to 4 mg l1 (maximum concentration of 7 mg l1) and 8 to 12 mg l1 (maximum concentration of 22 mg l1) on the south flank of Georges Bank. ?? 1987.

  12. Study on the interrelated effects of capillary diameter, background electrolyte concentration, and flow rate in pressure assisted capillary electrophoresis with contactless conductivity detection.

    Science.gov (United States)

    Mai, Thanh Duc; Hauser, Peter C

    2013-06-01

    A detailed study on the effect of the buffer concentration and the magnitude of the superimposed hydrodynamic flow on separation performance in CZE with contactless conductivity detection was carried out with capillaries of 10, 25, and 50 μm internal diameter. It was confirmed that capillaries of narrow internal diameters require higher buffer concentrations for best sensitivities. For all diameters it was found that electrodispersion was the most pronounced band-broadening factor for relatively long residence times. For shorter times, Joule heating related band broadening appears to be the most significant factor, which means that best separation efficiencies are obtained with the narrowest capillaries. As detection limits are as good for capillaries of 10 μm internal diameters as for the other diameters when using contactless conductivity detection, these narrow capillaries are, therefore, generally of benefit when employing this detection technique. Hydrodyamic flow was found to have only a very limited effect on band broadening; an effect was only noticeable for the 50 μm capillary and relatively high flow rates. PMID:23417350

  13. Carbon-13 isotopic abundance and concentration of atmospheric methane for background air in the Southern and Northern Hemispheres from 1978 to 1989

    International Nuclear Information System (INIS)

    Atmospheric methane (CH4) may become an increasingly important contributor to global warming in future years. Its atmospheric concentration has risen, doubling over the past several hundred years, and additional methane is thought to have a much greater effect on climate, on a per molecule basis, than additional C02 at present day concentrations (Shine et al. 1990). The causes of the increase of atmospheric CH4 have been difficult to ascertain because of a lack of quantitative knowledge of the fluxes (i.e., net emissions) from the numerous anthropogenic and natural sources. The goal of CH4 isotopic studies is to provide a constraint (and so reduce the uncertainties) in estimating the relative fluxes from the various isotopically distinct sources, whose combined fluxes must result in the measured atmospheric isotopic composition, after the fractionating effect of the atmospheric removal process is considered. In addition, knowledge of the spatial and temporal changes in the isotopic composition of atmospheric CH4, along with estimates of the fluxes from some of the major sources, makes it possible to calculate growth rates for sources whose temporal emissions trends would be difficult to measure directly

  14. Carbon-13 isotopic abundance and concentration of atmospheric methane for background air in the Southern and Northern Hemispheres from 1978 to 1989

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, C.M. [Argonne National Lab., IL (United States); Sepanski; Morris, L.J. [Univ. of Tennessee, Knoxville, TN (United States). Energy, Environment, and Resources Center

    1995-03-01

    Atmospheric methane (CH{sub 4}) may become an increasingly important contributor to global warming in future years. Its atmospheric concentration has risen, doubling over the past several hundred years, and additional methane is thought to have a much greater effect on climate, on a per molecule basis, than additional C0{sub 2} at present day concentrations (Shine et al. 1990). The causes of the increase of atmospheric CH{sub 4} have been difficult to ascertain because of a lack of quantitative knowledge of the fluxes (i.e., net emissions) from the numerous anthropogenic and natural sources. The goal of CH{sub 4} isotopic studies is to provide a constraint (and so reduce the uncertainties) in estimating the relative fluxes from the various isotopically distinct sources, whose combined fluxes must result in the measured atmospheric isotopic composition, after the fractionating effect of the atmospheric removal process is considered. In addition, knowledge of the spatial and temporal changes in the isotopic composition of atmospheric CH{sub 4}, along with estimates of the fluxes from some of the major sources, makes it possible to calculate growth rates for sources whose temporal emissions trends would be difficult to measure directly.

  15. Study on contamination control in a minienvironment inside clean room for yield enhancement based on particle concentration measurement and airflow CFD simulation

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Kwang-Chul [Department of Mechanical Engineering, Yonsei University, Seoul 120-749 (Korea); Kim, Hyuk-Soon; Oh, Myung-Do [Department of Mechanical and Information Engineering, University of Seoul, Seoul 130-743 (Korea)

    2010-04-15

    A study was carried out to look for the source of contamination and examine the route of contaminant transfer in the minienvironment applied in LCD process clean room of Korea. As the minienvironment model, one of the clean room with much large space and low particle concentration was selected to investigate. Firstly, the particle concentrations were measured without any information on the source and the route of contaminants transfer. Through considering the results of particle measurements and CFD simulations simultaneously, however, it was revealed that the critical contamination source was the stocker and the contaminants were transferred by the airflow pattern in this study. As an improvement action, reducing the airflow rate of exhaust fans and installing additional fan filter units (FFUs) were carried out. As a result, the velocity distribution was improved and the particle concentration was reduced in the target minievironment. Also, the defect rate related to this minienvironment decreased. With the help of the experimental and the numerical tools, the effective method for contamination control was developed. Furthermore, this article provides recommendation for future work to improve the yield and save the energy consumption simultaneously. (author)

  16. Effects of terahertz radiation at atmospheric oxygen frequency of 129 GHz on blood nitrite concentrations under conditions of different types of stress against the background of administration of nonselective inhibitor of constitutive NO-synthases.

    Science.gov (United States)

    Kirichuk, V F; Tsymbal, A A

    2012-02-01

    We studied the effect of terahertz radiation at atmospheric oxygen frequency 129 GHz on blood nitrite concentration in different types of experimental stress against the background of administration of nonselective inhibitor of constitutive NO-synthases. Normalizing effects of radiation on blood nitrite dynamics in animals with acute stress was shown after 15-min exposure and in animals with chronic stress after 30-min exposure. No positive effect of terahertz radiation was observed on altered blood nitrite concentration in male rats after preliminary administration of nonselective constitutive NO-synthase isoform inhibitor L-NAME. PMID:22803105

  17. Metal concentration and bioaccessibility in different particle sizes of dust and aerosols to refine metal exposure assessment.

    Science.gov (United States)

    Goix, Sylvaine; Uzu, Gaëlle; Oliva, Priscia; Barraza, Fiorella; Calas, Aude; Castet, Sylvie; Point, David; Masbou, Jeremy; Duprey, Jean-Louis; Huayta, Carlos; Chincheros, Jaime; Gardon, Jacques

    2016-11-01

    Refined exposure assessments were realized for children, 7-9yrs, in the mining/smelting city of Oruro, Bolivia. Aerosols (PM>2.5, PM1-2.5, PM0.4-1 and PM0.5) and dust (separated in different particle size fractions: 2000-200μm, 200-50μm, 50-20μm, 20-2μm and assessed considering actual external exposure (i.e. exposure pathways: metals inhaled and ingested) and simulated internal exposure (i.e., complex estimation using gastric and lung bioaccessibility, deposition and clearance of particles in lungs). Significant differences between external and simulated internal exposure were attributed to dissemblances in gastric and lung bioaccessibilities, as well as metal distribution within particle size range, revealing the importance of both parameters in exposure assessment. PMID:27344256

  18. Particles fluidized bed receiver/reactor with a beam-down solar concentrating optics: 30-kWth performance test using a big sun-simulator

    Science.gov (United States)

    Kodama, Tatsuya; Gokon, Nobuyuki; Cho, Hyun Seok; Matsubara, Koji; Etori, Tetsuro; Takeuchi, Akane; Yokota, Shin-nosuke; Ito, Sumie

    2016-05-01

    A novel concept of particles fluidized bed receiver/reactor with a beam-down solar concentrating optics was performed using a 30-kWth window type receiver by a big sun-simulator. A fluidized bed of quartz sand particles was created by passing air from the bottom distributor of the receiver, and about 30 kWth of high flux visible light from 19 xenon-arc lamps of the sun-simulator was directly irradiated on the top of the fluidized bed in the receiver through a quartz window. The particle bed temperature at the center position of the fluidized bed went up to a temperature range from 1050 to 1200°C by the visible light irradiation with the average heat flux of about 950 kW/m2, depending on the air flow rate. The output air temperature from the receiver reached 1000 - 1060°C.

  19. Exact Solution of Fractional Diffusion Model with Source Term used in Study of Concentration of Fission Product in Uranium Dioxide Particle*

    Institute of Scientific and Technical Information of China (English)

    FANG Chao; CAO Jian-Zhu; SUN Li-Feng

    2011-01-01

    The exact solution of fractional diffusion model with a location-independent source term used in the study of the concentration of fission product in spherical uranium dioxide (U02) particle is built. The adsorption effect of the fission product on the surface of the U02 particle and the delayed decay effect are also considered. The solution is given in terms of Mittag-Leffler function with finite Hankel integral transformation and Laplace transformation. At last, the reduced forms of the solution under some special physical conditions, which is used in nuclear engineering, are obtained and corresponding remarks are given to provide significant exact results to the concentration analysis of nuclear fission products in nuclear reactor.

  20. Particle size distributions, PM2.5 concentrations and water- soluble inorganic ions in different public indoor environments: a case study in Jinan, China

    Institute of Scientific and Technical Information of China (English)

    Can DONG; Lingxiao YANG; Chao YAN; Qi YUAN; Yangchun YU; Wenxing WANG

    2013-01-01

    In this study, we collected particles with aerodynamic diameter≤2.5μm (PM2.5) from three different public indoor places (a supermarket, a commercial office, and a university dining hall) in Jinan, a medium-sized city located in northern China. Water- soluble inorganic ions of PM2.5 and particle size distributions were also measured. Both indoor and outdoor PM2.5 levels (102.3-143.8 μg·m- 3 and 160.2-301.3 μg·m-3, respectively) were substantially higher than the value recommended by the World Health Organization (25 I.μg·m-3), and outdoor sources were found to be the major contributors to indoor pollutants. Diurnal particle number size distributions were different, while the maximum volume concentrations all appeared to be approximately 300nm in the three indoor locations. Concentrations of indoor and outdoor PM2.5 were shown to exhibit the same variation trends for the supermarket and dining hall. For the office, PM2.5 concentrations during nighttime were observed to decrease sharply. Among others, SO42-, NH4+ and NO3- were found to be the dominant water-soluble ions of both indoor and outdoor particles. Concentrations of NO3- in the supermarket and office during the daytime were observed to decrease sharply, which might be attributed to the fact that the indoor temperature was much higher than the outdoor temperature. In addition, domestic activities such as cleaning, water usage, cooking, and smoking also played roles in degraded indoor air quality. However, the results obtained here might be negatively impacted by the small number of samples and short sampling durations.

  1. Diurnal concentrations variations, size distributions for ambient air particles and metallic pollutants (Cr, Mn, Ni, Cd, Pb) during summer season at a traffic area.

    Science.gov (United States)

    Fang, Guor-Cheng; Kuo, Yu-Chen; Zhuang, Yuan-Jie; Chen, Yu-Cheng

    2014-07-01

    This study characterized and discussed particulate ambient air particulate concentrations and seasonal variations for PM18, PM10, PM2.5, and PM1 during June 2013-July 2013 at this traffic sampling site. In addition, this study also characterized the ambient air particulates size distributions by using MOUDI-100S4 sampler to collect 1-day the ambient suspended particles (PM18, PM10, PM2.5, and PM1) at this sampling site. In addition, the study also showed that the main pollutants contributions were from traffic and residual areas. As for the pollutants seasonal concentrations variations, the results indicated that the average particle concentrations orders were all displayed as daytime > nighttime for PM18, PM10, PM2.5 and PM1 at this characteristic sampling site. The results further indicated that the mean highest of metal concentrations in this study indicated that the average metal concentration were all displayed as Mn > Cr > Ni > Pb > Cd for PM18, PM10, PM2.5 and PM1 on daytime and nighttime at this characteristic sampling site. PMID:24619364

  2. Prediction of indoor concentration of 0.5-4 µm particles of outdoor origin in an uninhabited apartment

    DEFF Research Database (Denmark)

    Schneider, T.; Jensen, K.A.; Clausen, P.A.;

    2004-01-01

    apartments. The results suggest that factors such as particle chemical composition, within building transport patterns, and occupant behaviour in other apartments should be identified and quantified in future studies, and that these factors need to be included in predictive models. (C) 2004 Elsevier Ltd. All...

  3. Electric response of a magnetic colloid to periodic external excitation for different nanoparticles concentrations: Determination of the particles' effective charge

    Science.gov (United States)

    Batalioto, F.; Barbero, G.; Sehnem, A. L.; Figueiredo Neto, A. M.

    2016-08-01

    The effective electric charge of a nanoparticle in an ionic magnetic colloidal system (an ionic ferrofluid) is determined by using the impedance spectroscopy technique. The electric response of the samples to a harmonic external electric field excitation is described by means of the Poisson-Nernst-Planck model. The model proposed for the theoretical interpretation of the impedance spectroscopy data considers that the magnetic particles are electrically charged with H+ and have in their vicinity Cl- counterions, resulting in an effective charge Qeff. In the presence of an harmonic, in time, external field (frequency bigger than 10 4 Hz ) particles are assumed to be at rest, due to inertial reason. In this framework, the response of the cell is due to the H+ and Cl- present in the solution. From the spectra of the real and imaginary components of the electric impedance of the cell, by means of a best fit procedure to our model, we derive the effective electric charge of the magnetic particles and the bulk density of ions. From an independent measurement of the ζ-potential of the suspension, it is possible to calculate the hydrodynamic radius of the particle, in good agreement with that independently measured.

  4. How Sensitive Is the Elasticity of Hydroxyapatite-Nanoparticle-Reinforced Chitosan Composite to Changes in Particle Concentration and Crystallization Temperature?

    Directory of Open Access Journals (Sweden)

    Kean Wang

    2015-10-01

    Full Text Available Hydroxyapatite (HA nanoparticle-reinforced chitosan composites are biocompatible and biodegradable structural materials that are used as biomaterials in tissue engineering. However, in order for these materials to function effectively as intended, e.g., to provide adequate structural support for repairing damaged tissues, it is necessary to analyse and optimise the material processing parameters that affect the relevant mechanical properties. Here we are concerned with the strength, stiffness and toughness of wet-spun HA-reinforced chitosan fibres. Unlike previous studies which have addressed each of these parameters as singly applied treatments, we have carried out an experiment designed using a two-factor analysis of variance to study the main effects of two key material processing parameters, namely HA concentration and crystallization temperature, and their interactions on the respective mechanical properties of the composite fibres. The analysis reveals that significant interaction occurs between the crystallization temperature and HA concentration. Starting at a low HA concentration level, the magnitude of the respective mechanical properties decreases significantly with increasing HA concentration until a critical HA concentration is reached, at around 0.20–0.30 (HA mass fraction, beyond which the magnitude of the mechanical properties increases significantly with HA concentration. The sensitivity of the mechanical properties to crystallization temperature is masked by the interaction between the two parameters—further analysis reveals that the dependence on crystallization temperature is significant in at least some levels of HA concentration. The magnitude of the mechanical properties of the chitosan composite fibre corresponding to 40 °C is higher than that at 100 °C at low HA concentration; the reverse applies at high HA concentration. In conclusion, the elasticity of the HA nanoparticle-reinforced chitosan composite fibre is

  5. Cytotoxic and mutagenic effects, particle size and concentration analysis of diesel engine emissions using biodiesel and petrol diesel as fuel

    Energy Technology Data Exchange (ETDEWEB)

    Buenger, J.; Mueller, M.M.; Westphal, G.; Ruhnau, P.; Schulz, T.G.; Hallier, E. [Inst. fuer Arbeits- und Sozialmedizin, Georg-August-Univ., Goettingen (Germany); Krahl, J.; Baum, K.; Schroeder, O. [Inst. fuer Technologie und Biosystemtechnik, Bundesforschungsanstalt fuer Landwirtschaft, Braunschweig (Germany)

    2000-10-01

    Diesel engine exhaust particles (DEP) contribute substantially to ambient air pollution. They cause acute and chronic adverse health effects in humans. Biodiesel (rapeseed oil methyl ester, RME) is used as a ''green fuel'' in several countries. For a preliminary assessment of environmental and health effects of RME, the particulate-associated emissions from the DEP of RME and common fossil diesel fuel (DF) and their in vitro cytotoxic and mutagenic effects were compared. A test tractor was fuelled with RME and DF and driven in a European standard test cycle (ECE R49) on an engine dynamometer. Particle numbers and size distributions of the exhausts were determined at the load modes ''idling'' and ''rated power''. Filter-sampled particles were extracted and their cytotoxic properties tested using the neutral red assay. Mutagenicity was tested using the Salmonella typhimurium/microsome assay. Despite higher total particle emissions, solid particulate matter (soot) in the emissions from RME was lower than in the emissions from DF. While the size distributions and the numbers of emitted particles at ''rated power'' were nearly identical for the two fuels, at ''idling'' DF emitted substantially higher numbers of smaller particles than RME. The RME extracts caused fourfold stronger toxic effects on mouse fibroblasts at ''idling'' but not at ''rated power'' than DF extracts. The extracts at both load modes were significantly mutagenic in TA98 and TA100. However, extracts of DF showed a fourfold higher mutagenic effect in TA98 (and twofold in TA100) than extracts of RME. These results indicate benefits as well as disadvantages for humans and the environment from the use of RME as a fuel for tractors. The lower mutagenic potency of DEP from RME compared to DEP from DF is probably due to lower emissions of polycyclic aromatic compounds

  6. Gas-particle concentration, distribution, and health risk assessment of polycyclic aromatic hydrocarbons at a traffic area of Giza, Egypt.

    Science.gov (United States)

    Hassan, Salwa Kamal; Khoder, M I

    2012-06-01

    Atmospheric particulate and gaseous polycyclic aromatic hydrocarbons (PAHs) samples were collected from an urban area in Dokki (Giza) during the summer of 2007 and the winter of 2007-2008. The average concentrations of PAHs were 1,429.74 ng/m(3) in the particulate phase, 2,912.56 ng/m(3) in the gaseous phase, and 4,342.30 ng/m(3) in the particulate + gaseous phases during the period of study. Dokki has high level concentrations of PAH compounds compared with many polluted cities in the world. The concentrations of PAH compounds in the particulate and gaseous phases were higher in the winter and lower in the summer. Total concentrations of PAHs in the particulate phase and gaseous phase were 22.58% and 77.42% in summer and 36.97% and 63.03% in winter of the total (particulate + gaseous) concentrations of PAHs, respectively. The gaseous/particulate ratios of PAHs concentration were 3.43 in summer and 1.71 in winter. Significant negative correlation coefficients were found between the ambient temperature and concentrations of the total PAHs in the particulate and gaseous phases. The distribution of individual PAHs and different categories of PAHs based on aromatic ring number in the particulate and gaseous phases during the summer and winter were nearly similar, indicating similar emission sources of PAHs in both two seasons. Benzo(b)fluoranthene in the particulate phase and naphthalene in the gaseous phase were the most abundant compounds. Diagnostic concentration ratios of PAH compounds indicate that these compounds are emitted mainly from pyrogenic sources, mainly local vehicular exhaust emissions. Health risks associated with the inhalation of individual PAHs in particulate and gaseous phases were assessed on the basis of its benzo(a)pyrene equivalent concentration. Dibenzo(a,h)anthracene and benzo(a)pyrene in the particulate phase and benzo(a)pyrene and benzo(a)anthracene in the gaseous phase were the greatest contributors to the total health risks. The

  7. Resonance strengths in the 17,18O(p, α)14,15N reactions and background suppression underground. Commissioning of a new setup for charged-particle detection at LUNA

    International Nuclear Information System (INIS)

    We report on measurements of resonance strengths and energies for the Ep = 151 and 193 keV resonances in the 18O(p, α)15N and 17O(p, α)14N reactions, respectively, obtained during commissioning of a new setup for alpha-particle detection studies at the LUNA underground laboratory. Our values, ωγ(151) = 164.2 ± 0.9stat-11.7+12.1syst meV and ωγ (193) = 1.68 ± 0.03stat ± 0.12syst meV, are in excellent agreement with those reported in the literature. New values of resonance energies are Ep = 151.2 ± 0.3 keV and Ep = 194.8 ± 0.3 keV, respectively, this latter with the highest precision to date. Comparative background measurements in silicon detectors overground and underground were also carried out, yielding up to a factor of 15 in background suppression at LUNA at energies around 200 keV. This clearly demonstrates the usefulness of underground measurements in charged-particles experiments, especially at low detection energies. (orig.)

  8. Resonance strengths in the {sup 17,18}O(p, α){sup 14,15}N reactions and background suppression underground. Commissioning of a new setup for charged-particle detection at LUNA

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, C.G.; Scott, D.A.; Aliotta, M.; Davinson, T.; Griffin, C.J. [University of Edinburgh, SUPA, School of Physics and Astronomy, Edinburgh (United Kingdom); Formicola, A.; Best, A.; Junker, M. [Laboratori Nazionali del Gran Sasso, INFN, Assergi (Italy); Anders, M.; Bemmerer, D.; Szuecs, T. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Broggini, C.; Menegazzo, R. [INFN, Padova (Italy); Caciolli, A.; Depalo, R. [INFN, Padova (Italy); Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); Cavanna, F.; Corvisiero, P.; Prati, P. [INFN, Genova (Italy); Dipartimento di Fisica, Universita di Genova, Genova (Italy); Di Leva, A.; Imbriani, G. [Universita di Napoli ' ' Federico II' ' , Dipartimento di Scienze Fisiche, Napoli (Italy); Elekes, Z.; Fueloep, Zs.; Gyuerky, Gy.; Somorjai, E. [MTA Atomki, Institute of Nuclear Research, Debrecen (Hungary); Gervino, G. [Universita degli Studi di Torino, Dipartimento di Fisica Sperimentale, Torino (Italy); Guglielmetti, A.; Trezzi, D. [Universita degli Studi di Milano (Italy); INFN, Milano (Italy); Gustavino, C. [INFN, Roma (Italy); Napolitani, E. [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); Straniero, O. [Laboratori Nazionali del Gran Sasso, INFN, Assergi (Italy); Osservatorio Astronomico di Collurania, Teramo (Italy); Strieder, F. [South Dakota School of Mines and Technology, Rapid City, SD (United States); Collaboration: LUNA Collaboration

    2015-08-15

    We report on measurements of resonance strengths and energies for the E{sub p} = 151 and 193 keV resonances in the {sup 18}O(p, α){sup 15}N and {sup 17}O(p, α){sup 14}N reactions, respectively, obtained during commissioning of a new setup for alpha-particle detection studies at the LUNA underground laboratory. Our values, ωγ(151) = 164.2 ± 0.9{sub stat-11.7}{sup +12.1}{sub syst} meV and ωγ (193) = 1.68 ± 0.03{sub stat} ± 0.12{sub syst} meV, are in excellent agreement with those reported in the literature. New values of resonance energies are E{sub p} = 151.2 ± 0.3 keV and E{sub p} = 194.8 ± 0.3 keV, respectively, this latter with the highest precision to date. Comparative background measurements in silicon detectors overground and underground were also carried out, yielding up to a factor of 15 in background suppression at LUNA at energies around 200 keV. This clearly demonstrates the usefulness of underground measurements in charged-particles experiments, especially at low detection energies. (orig.)

  9. Change of Primary Cosmic Radiation Nuclear Conposition in the Energy Range $10^{15} - 10^{17}$ eV as a Result of the Interaction with the Interstellar Cold Background of Light Particles

    CERN Document Server

    Barnaveli, T T; Khaldeeva, I V

    2003-01-01

    In this paper the updated arguments in favor of a simple model, explaining from the united positions all peculiarities of the Extensive Air Shower (EAS) hadron E_h(E_0) (and muon E_mu(E_0)) component energy fluxes dependence on the primary particle energy E_0 in the primary energy region 10^{15} - 10^{17} eV are represented. These peculiarities have shapes of consequent distinct deeps of a widths dE_h/E_h of the order of 0.2 and of relative amplitudes dL/L of the order of {0.1 - 1.0}, and are difficult to be explained via known astrophysical mechanisms of particle generation and acceleration. In the basis of the model lies the destruction of the Primary Cosmic Radiation (PCR) nuclei on some monochromatic background of interstellar space, consisting of the light particles of the mass in the area of 36 eV (maybe the component of a dark matter). The destruction thresholds of PCR different nuclear components correspond to the peculiarities of E_h(E_0). In this work the results of the recent treatment of large sta...

  10. The influence of particle size and AgNO{sub 3} concentration in the ionic exchange process on the fungicidal action of antimicrobial glass

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, E.; Piletti, R. [Programa de Pos-Graduacao em Engenharia Quimica Universidade Federal de Santa Catarina - UFSC, Florianopolis, Santa Catarina (Brazil); Barichello, T. [Programa de Pos-Graduacao em Ciencias da Saude, Universidade do Extremo Sul Catarinense - UNESC, Criciuma, Santa Catarina (Brazil); Oliveira, C.M. [Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, Universidade do Extremo Sul Catarinense - UNESC, Criciuma, Santa Catarina (Brazil); Kniess, C.T. [Programa de Mestrado Profissional em Administracao - Gestao de Projetos, Universidade Nove de Julho, Sao Paulo, Sao Paulo (Brazil); Angioletto, E. [Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, Universidade do Extremo Sul Catarinense - UNESC, Criciuma, Santa Catarina (Brazil); Riella, H.G. [Programa de Pos-Graduacao em Engenharia Quimica Universidade Federal de Santa Catarina - UFSC, Florianopolis, Santa Catarina (Brazil); and others

    2012-08-01

    Antimicrobial materials have long been used as an effective means of reducing the risks posed to humans by fungi, bacteria and other microorganisms. These materials are essential in environments where cleanliness, comfort and hygiene are the predominate concerns. This work presents preliminary results for the development of a fungicidal vitreous material that is produced by the incorporation of a silver ionic specimen through ionic exchange reactions. Silver ions were incorporated into powdered glass via ionic exchange in an ionic medium containing silver species with different concentrations of AgNO{sub 3}. The fungicidal efficiency of the samples was studied as a function of the AgNO{sub 3} concentration and the particle size of the glass using the agar diffusion test for the microbiological analysis of the fungus species Candida albicans. The samples were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The experimental results showed that the fungicidal effect was dependent on the AgNO{sub 3} concentration in the ionic exchange medium but was not dependent on the particle size of the glass. - Highlights: Black-Right-Pointing-Pointer The fungicidal powder glass presents high potential for application as polymeric additive and others application in the medical area. Black-Right-Pointing-Pointer The fungicidal effect was dependent on AgNO3 concentration, but was not dependent on the particle size of the glass. Black-Right-Pointing-Pointer The XRD results show that the ionic exchange process promotes the formation of silver crystalline phases with cubic cells.

  11. Vertical distribution of trace-element concentrations and occurrence of metallurgical slag particles in accumulated bed sediments of Lake Roosevelt, Washington, September 2002

    Science.gov (United States)

    Cox, S.E.; Bell, P.R.; Lowther, J.S.; Van Metre, P.C.

    2005-01-01

    observed in cores from along the pre-reservoir Columbia River. Particles of slag, which have physical and chemical characteristics of slag discharged to the Columbia River by a lead-zinc smelter upstream of the reservoir at Trail, British Columbia, were found in sediments of Lake Roosevelt. Slag particles are more common in the upstream reaches of the reservoir. The chemical composition of the interior matrix of slag collected from Lake Roosevelt closely approximated the reported elemental concentrations of fresh smelter slag, although evidence of slag weathering was observed. Exfoliation flakes were observed on the surface of weathered slag particles isolated from the core sediments. The concentrations of zinc on the exposed surface of slag grains were smaller than concentrations on interior surfaces. Weathering rinds also were observed in the cross section of weathered slag grains, indicating that the glassy slag material was undergoing hydration and chemical weathering. Trace elements observed in accumulated sediments in the middle and lower reaches of the reservoir are more likely due to the input from liquid effluent discharges compared to slag discharges from the upstream smelter.

  12. The formation and evolution of young low-mass stars within halos with high concentration of dark matter particles

    CERN Document Server

    Casanellas, Jordi

    2009-01-01

    The formation and evolution of low-mass stars within dense halos of dark matter (DM) leads to evolution scenarios quite different from the classical stellar evolution. As a result of our detailed numerical work, we describe these new scenarios for a range of DM densities on the host halo, a range of scattering cross sections of the DM particles considered, and for stellar masses from 0.7 to 3 M$_{\\odot}$. For the first time, we also computed the evolution of young low-mass stars in their Hayashi track in the pre-main sequence phase and found that, for high DM densities, these stars stop their gravitational collapse before reaching the main sequence, in agreement with similar studies on first stars. Such stars remain indefinitely in an equilibrium state with lower effective temperatures ($|\\Delta T_{eff} |>10^{3} $K for a star of one solar mass), the annihilation of captured DM particles in their core being the only source of energy. In the case of lower DM densities, these proto-stars continue their collapse ...

  13. A comparison of temporal variation of particle-bound polycyclic aromatic hydrocarbons (pPAHs) concentration in different urban environments: Tokyo, Japan, and Bangkok, Thailand

    Science.gov (United States)

    Chetwittayachan, T.; Shimazaki, D.; Yamamoto, K.

    A comparative study of the real-time ambient concentrations of particle-bound polycyclic aromatic hydrocarbons (pPAHs) in the vicinity of roads in Tokyo (Japan) and in Bangkok (Thailand) in summertime was carried out by using a photoelectric aerosol sensor (PAS), which gives continuous signal in relation to the total amount of pPAHs concentration. The PAS output gave a good correlation to the total concentration of the selected PAHs determined by gas chromatography/mass spectrometry (GC/MS). This technique was then employed to observe temporal variation of total pPAHs. The measurements at roadside and general areas in Tokyo and in Bangkok were performed for seven consecutive days in August 2000, and in March 2001, respectively. The diurnal profiles of pPAHs concentrations in both cities were generally similar; explicit peak concentrations were observed in early morning in association with the traffic growth in the morning rush hours. A significant reduction occurred during the daytime was probably due to rising in the mixing zone. At roadside areas, the average pPAHs concentrations throughout the sampling period in Bangkok were significantly higher than those of Tokyo, owing to the larger contribution of vehicular traffic, especially heavy-duty vehicles, on the roads near the sampling site. Otherwise, all average concentrations in the general area in Tokyo were slightly higher than that of Bangkok. This was probably due to the percentage of road coverage in Tokyo being higher than that in Bangkok, creating a higher possibility for pPAHs evolving from road traffic, and the transportation pattern of the pPAHs in Tokyo showed a more broadly diffused profile than that of Bangkok. This suggests the widespread dispersion of pPAHs over the entire study area in Tokyo. At this study scale especially at the roadside, however, a high pPAHs concentration observed in Tokyo and in Bangkok was predominantly located at low wind speed, roads.

  14. Low hazard refractive index and density-matched fluid for quantitative imaging of concentrated suspensions of particles

    Science.gov (United States)

    Zhu, W.; Knapp, Y.; Deplano, V.

    2016-05-01

    A novel refractive index and density-matched liquid-solid suspension system taking into account chemical hazard and health concerns was developed and characterized. The solid phase is made of PMMA spheres, the refractive index of which being adapted with a mixture of 2,2'-thiodiethanol and phosphate-buffered saline (PBS), while the density is adapted with a mixture of PBS and glycerol. The proposed chemicals present low hazard characteristics in comparison with former solutions. Data collected from density and refractive index measurements of the solid phase and of the different fluid constituents are used to define a specific ternary mixture adapted to commercial grade micron-size particles. The defined mixture is validated in a micron-sized granular flow experiment. The described method can be applied to other low-density solids.

  15. Suspended particulate matter in New York City: element concentrations as a function of particle size and elevation above street

    International Nuclear Information System (INIS)

    Aerosol samples were simultaneously collected at two street-level locations and the 16th floor, on two sides of a Manhattan city block. The results of PIXE analysis, together with CO and SO2 data, show that the concentrations of substances emitted at street level (CO, Pb, etc) are significantly less at the 16th floor whereas particulate sulfur shows little variation. Other conclusions are presented

  16. Evaluation of building characteristics in 27 dwellings in Denmark and the effect of using particle filtration units on PM2.5 concentrations

    DEFF Research Database (Denmark)

    Spilak, Michal P.; Loft, Steffen

    2014-01-01

    levels of particulate matter and building characteristics; and the use of PFU as a way to effectively reduce the levels of PM2.5 indoors.The results obtained from the study have shown that a small room area, wooden floor material, or the use of gas for cooking is strongly associated with high PM2.5 mass......Exposure to airborne particulate matter in homes is associated with the risk of cardiovascular diseases and respiratory problems. Due to the extended time people spend at home, reducing the particle concentration in homes may be a means to reduce the risk of cardiovascular diseases and respiratory...

  17. Study on the concentration variation of CO2 in the background area of Yangtze River Delta%长江三角洲背景地区CO2浓度变化特征研究

    Institute of Scientific and Technical Information of China (English)

    浦静姣; 徐宏辉; 顾骏强; 周凌晞; 方双喜

    2012-01-01

    Atmospheric CO2 concentration was continuously measured from January 2009 to December 2010 to study the effects of surface wind direction, surface wind speed and air mass transport on CO2 concentration at Lin'an regional atmospheric background station. The results revealed that the diurnal variation of atmospheric CO2 concentration showed the single-peak pattern at Lin'an regional background station. The diurnal concentration of CO2 varied from 9.5×10-6(VIV) to 44.3×10-6 (V/V), with the lowest value observed in the afternoon and the highest at dawn. The difference between maximum and minimum monthly mean CO2 concentrations was 10.1xl0-6(VIV), with the highest concentration observed in winter and spring and the lowest in summer. Study on the effects of surface wind direction, surface wind speed and air mass transport on CO2 concentration showed the dominant wind directions were NW-NNE in summer and NNE-ESE in winter, which could bring on higher CO2 concentration. The CO2 concentration turned lower with higher surface wind speed. The impact of long-range transport of air masses on CO2 concentration depended on the source strength of CO2 in the pathway.%通过分析2009年1月~2010年12月临安区域大气本底站在线观测获得的CO2浓度,研究地面风向、地面风速、气团输送等因素对长江三角洲背景地区CO2浓度的影响.结果表明,临安站CO2浓度的日变化分布表现为单峰型形态,下午低、凌晨高,浓度日变幅在9.5×10 6~44.3×10 6(V/V)之间;季节变化特征表现为冬春季高,夏季低,浓度年较差为10.1×10-6(V/V).通过分析地面风向、地面风速和气团输送等因素对临安站CO2浓度的影响表明,引起CO2浓度升高的地面风向夏季主要为NW~NNE,冬季主要为NNE-ESE;地面风速越大,CO2浓度越小;气团远距离输送的影响主要取决于气团途径区域的CO2排放情况.

  18. Concentrations and solubility of trace elements in fine particles at a mountain site, southern China: regional sources and cloud processing

    OpenAIRE

    T. Li; Y Wang; Li, W. J.; Chen, J. M.; Wang, T; Wang, W. X.

    2015-01-01

    The concentrations and solubility of twelve trace elements in PM2.5 at Mt. Lushan, southern China, were investigated during the summer of 2011 and the spring of 2012. The average PM2.5 mass was 55.2 ± 20.1 μg m-3 during the observation period. Temporal variations of all trace elements including total and water-soluble fractions with several dust storm spikes for total fraction Al and Fe were observed. The enrichment factor (EF)...

  19. Concentrations and solubility of trace elements in fine particles at a mountain site, southern China: regional sources and cloud processing

    OpenAIRE

    T. Li; Y Wang; Li, W. J.; Chen, J. M.; Wang, T; Wang, W. X.

    2015-01-01

    The concentrations and solubility of twelve trace elements in PM2.5 at Mt. Lushan, southern China, were investigated during the summer of 2011 and the spring of 2012. The average PM2.5 mass was 55.2 ± 20.1 μg m−3 during the observation period. Temporal variations of all trace elements including total and water-soluble fractions with several dust storm spikes in total fractions of Al and Fe were observed. The enrichment factor (EF) values were 1 order of magnitude higher ...

  20. Concentrations and chemical compositions of fine particles (PM2.5) during haze and non-haze days in Beijing

    Science.gov (United States)

    Zhang, Yang; Huang, Wei; Cai, Tianqi; Fang, Dongqing; Wang, Yuqin; Song, Jian; Hu, Min; Zhang, Yuanxun

    2016-06-01

    To investigate the chemical properties of PM2.5 and put forward reasonable control measures, daily samples of PM2.5 were collected at an urban site in Beijing from August 4 to September 3 of 2012 using two 2-channel samplers. Chemical analysis was conducted for eight water soluble inorganic ions (WSII, including Na+, NH4+, K+, Mg2 +, Ca2 +, Cl-, NO3-, and SO42 -), organic carbon (OC) and elementary carbon (EC). PM2.5 concentrations ranged from 8.8 to 218.6 μg m- 3, with an average concentration of 80.6 ± 57.3 μg m- 3. WSII, the most dominant PM2.5 constituents contributing 60 ± 18% of its mass, ranged from 3.1 to 172.2 μg m- 3. SO42 -, NO3-, and NH4+ dominated WSII (90 ± 28%) and their concentrations were 1.3-105.7 μg m- 3, 0.5-52.7 μg m- 3 and 0.3-33.5 μg m- 3, respectively. The concentrations of OC and EC were 3.0-28.8 μgC m- 3 and 0.8-7.4 μgC m- 3, constituting 17.6% and 4.9% of PM2.5, respectively. Three serious pollution episodes (haze days) occurred during the campaign. PM2.5 and its chemical species showed substantial increases during haze episodes. The greater enhancement factors for SO42 - (4.5), NO3- (4.0), and NH4+ (4.2) during haze days compared to non-haze days were obtained, suggesting that these secondary inorganic ions play important roles in the formation of haze. The average ratio of NO3-/SO42 - was 0.52. Ion balance calculations showed that PM2.5 samples were acidic during haze periods and close to neutral during non-haze days. Correlation analysis between the major ions was conducted and the results suggested that the main forms of NH4+ might be (NH4)2SO4. In addition, the variations between haze days and non-haze days for OC, EC, and the ratio of OC/EC were discussed.

  1. Atmospheric concentrations, sources and gas-particle partitioning of PAHs in Beijing after the 29th Olympic Games

    International Nuclear Information System (INIS)

    A comprehensive sampling campaign was carried out to study atmospheric concentration of polycyclic aromatic hydrocarbons (PAHs) in Beijing and to evaluate the effectiveness of source control strategies in reducing PAHs pollution after the 29th Olympic Games. The sub-cooled liquid vapor pressure (logPLo)-based model and octanol-air partition coefficient (Koa)-based model were applied based on each seasonal dateset. Regression analysis among log KP, logPLo and log Koa exhibited high significant correlations for four seasons. Source factors were identified by principle component analysis and contributions were further estimated by multiple linear regression. Pyrogenic sources and coke oven emission were identified as major sources for both the non-heating and heating seasons. As compared with literatures, the mean PAH concentrations before and after the 29th Olympic Games were reduced by more than 60%, indicating that the source control measures were effective for reducing PAHs pollution in Beijing. - Highlights: → This is the first comprehensive study of PAHs in atmosphere after the 29th Olympics in Beijing, China. → The air quality before and after 29th Olympics has attracted much attention worldwide. → The study was helpful for other countries to understand how the Olympics affected PAHs emissions. → The study would act as a case study to know the effects that big events can impose on the host cities. - The source control measures implemented before and during the 29th Olympic Games were effective for reducing the emissions of air pollutants in Beijing.

  2. Atmospheric concentrations, sources and gas-particle partitioning of PAHs in Beijing after the 29th Olympic Games

    Energy Technology Data Exchange (ETDEWEB)

    Ma Wanli [International Joint Research Center for Persistent Toxic Substances (IJRC-PTS), State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Sun Dezhi [International Joint Research Center for Persistent Toxic Substances (IJRC-PTS), State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083 (China); Shen Weiguo [College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083 (China); Yang Meng [IJRC-PTS, Dalian Maritime University, Dalian (China); Qi Hong; Liu Liyan; Shen Jimin [International Joint Research Center for Persistent Toxic Substances (IJRC-PTS), State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Li Yifan, E-mail: ijrc_pts_paper@yahoo.com [International Joint Research Center for Persistent Toxic Substances (IJRC-PTS), State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China); Science and Technology Branch, Environment Canada, Toronto, Ontario M3H5T4 (Canada)

    2011-07-15

    A comprehensive sampling campaign was carried out to study atmospheric concentration of polycyclic aromatic hydrocarbons (PAHs) in Beijing and to evaluate the effectiveness of source control strategies in reducing PAHs pollution after the 29th Olympic Games. The sub-cooled liquid vapor pressure (logP{sub L}{sup o})-based model and octanol-air partition coefficient (K{sub oa})-based model were applied based on each seasonal dateset. Regression analysis among log K{sub P}, logP{sub L}{sup o} and log K{sub oa} exhibited high significant correlations for four seasons. Source factors were identified by principle component analysis and contributions were further estimated by multiple linear regression. Pyrogenic sources and coke oven emission were identified as major sources for both the non-heating and heating seasons. As compared with literatures, the mean PAH concentrations before and after the 29th Olympic Games were reduced by more than 60%, indicating that the source control measures were effective for reducing PAHs pollution in Beijing. - Highlights: > This is the first comprehensive study of PAHs in atmosphere after the 29th Olympics in Beijing, China. > The air quality before and after 29th Olympics has attracted much attention worldwide. > The study was helpful for other countries to understand how the Olympics affected PAHs emissions. > The study would act as a case study to know the effects that big events can impose on the host cities. - The source control measures implemented before and during the 29th Olympic Games were effective for reducing the emissions of air pollutants in Beijing.

  3. Comparison of Spheroidal Carbonaceous Particle Data with Modelled Atmospheric Black Carbon Concentration and Deposition and Air Mass Sources in Northern Europe, 1850–2010

    Directory of Open Access Journals (Sweden)

    Meri Ruppel

    2013-01-01

    Full Text Available Spheroidal carbonaceous particles (SCP are a well-defined fraction of black carbon (BC, produced only by the incomplete combustion of fossil fuels such as coal and oil. Their past concentrations have been studied using environmental archives, but, additionally, historical trends of BC concentration and deposition can be estimated by modelling. These models are based on BC emission inventories, but actual measurements of BC concentration and deposition play an essential role in their evaluation and validation. We use the chemistry transport model OsloCTM2 to model historical time series of BC concentration and deposition from energy and industrial sources and compare these to sedimentary measurements of SCPs obtained from lake sediments in Northern Europe from 1850 to 2010. To determine the origin of SCPs we generated back trajectories of air masses to the study sites. Generally, trends of SCP deposition and modelled results agree reasonably well, showing rapidly increasing values from 1950, to a peak in 1980, and a decrease towards the present. Empirical SCP data show differences in deposition magnitude between the sites that are not captured by the model but which may be explained by different air mass transport patterns. The results highlight the need for numerous observational records to reliably validate model results.

  4. Simultaneous determination of Si, Al and Na concentrations by particle induced gamma-ray emission and applications to reference materials and ceramic archaeological artifacts

    Energy Technology Data Exchange (ETDEWEB)

    Dasari, K.B. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); GITAM Institute of Science, GITAM University, Visakhapatnam 530045 (India); Chhillar, S. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Acharya, R., E-mail: racharya@barc.gov.in [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Ray, D.K.; Behera, A. [Ion Beam Laboratory, Institute of Physics, Bhubaneswar 751005 (India); Lakshmana Das, N. [GITAM Institute of Science, GITAM University, Visakhapatnam 530045 (India); Pujari, P.K. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2014-11-15

    A particle induced gamma ray emission (PIGE) method using 4 MeV proton beam was standardized for simultaneous determination of Si, Al and Na concentrations and has been applied for non-destructive analysis of several reference materials and archaeological clay pottery samples. Current normalized count rates of gamma-rays for the three elements listed above were obtained by an in situ method using Li as internal standard. The paper presents application of the in situ current normalized PIGE method for grouping study of 39 clay potteries, obtained from Rajasthan and Andhra Pradesh states of India. Grouping of artifacts was carried out using the ratios of SiO{sub 2} to Al{sub 2}O{sub 3} concentrations, due to their non volatile nature. Powder samples and elemental standards in pellet forms (cellulose matrix) were irradiated using the 4 MeV proton beam (∼10 nA) from the 3 MV tandem accelerator at IOP Bhubaneswar, and assay of prompt gamma rays was carried out using a 60% relative efficiency HPGe detector coupled to MCA. The concentration ratio values of SiO{sub 2}/Al{sub 2}O{sub 3} indicated that pottery samples fell into two major groups, which are in good agreement with their collection areas. Reference materials from IAEA and NIST were analyzed for quantification of Si, Al and Na concentrations as a part of validation as well as application of PIGE method.

  5. Aerobyologic monitoring in urban and extra urban areas : analysis of airborne fungal particle concentration; Indagini aerobiologiche in ambiente urbano ed extraurbano componente fungina aerodiffusa

    Energy Technology Data Exchange (ETDEWEB)

    Bari, A. [ENEA, Saluggia (Italy). Centro Ricerche Energia; Caramiello, R.; Fossa, V.; Potenza, A. [Turin Univ. (Italy), Dip. di Biologia Vegetale

    1995-12-01

    In the environmental monitoring studies carried out by ENEA (Italian Agency for New Technologies, Energy and the Environment) a research about air quality of Turin and Saluggia (VC) has started in collaboration with the University of Turin. This research concerns the study of pollen and airborne fungal particle concentrations in the atmosphere. In the last few years the interest in airborne spores and hyphal fragments has increased. Indeed these particles play a very important role in allergic reactions, in several other human diseases, and in plant pathology. The incidence and the risk of infections by airborne fungal spores are correlated to the general climate and to the local micro climatic conditions; a complete aerosporological knowledge can be in many cases a useful indicator for infection risks. In this study the concentrations of airborne fungal spores in two different stations (urban station, Turin; and rural station, Saluggia (VC)) has been evaluated and compared, only for the year 1992, in order to verify the influence of climatic conditions and of floristic and vegetational aspects. In order to establish the correlations between the climate and the airborne fungal data, the results of aerosporogical analysis, relative to the Turin station, are reported. This investigation cover a six year period, three of which under standard climatic conditions and three with considerable peculiarities. A comparative evaluation of the efficiency in the collection of aerobiological particles (pollen and spores) by natural traps (mosses) has been attempted in Saluggia. The results obtained by this palinological analysis have been compared with the composition of the local flora and the data monitored by a spore-trap (volumetric pollen trap) positioned on the roof of a building in the ENEA Research Center of Saluggia.

  6. A comparison of temporal variation of particle-bound polycyclic aromatic hydrocarbons (pPAHs) concentration in different urban environments: Tokyo, Japan, and Bangkok, Thailand

    Science.gov (United States)

    Chetwittayachan, T.; Shimazaki, D.; Yamamoto, K.

    A comparative study of the real-time ambient concentrations of particle-bound polycyclic aromatic hydrocarbons (pPAHs) in the vicinity of roads in Tokyo (Japan) and in Bangkok (Thailand) in summertime was carried out by using a photoelectric aerosol sensor (PAS), which gives continuous signal in relation to the total amount of pPAHs concentration. The PAS output gave a good correlation to the total concentration of the selected PAHs determined by gas chromatography/mass spectrometry (GC/MS). This technique was then employed to observe temporal variation of total pPAHs. The measurements at roadside and general areas in Tokyo and in Bangkok were performed for seven consecutive days in August 2000, and in March 2001, respectively. The diurnal profiles of pPAHs concentrations in both cities were generally similar; explicit peak concentrations were observed in early morning in association with the traffic growth in the morning rush hours. A significant reduction occurred during the daytime was probably due to rising in the mixing zone. At roadside areas, the average pPAHs concentrations throughout the sampling period in Bangkok were significantly higher than those of Tokyo, owing to the larger contribution of vehicular traffic, especially heavy-duty vehicles, on the roads near the sampling site. Otherwise, all average concentrations in the general area in Tokyo were slightly higher than that of Bangkok. This was probably due to the percentage of road coverage in Tokyo being higher than that in Bangkok, creating a higher possibility for pPAHs evolving from road traffic, and the transportation pattern of the pPAHs in Tokyo showed a more broadly diffused profile than that of Bangkok. This suggests the widespread dispersion of pPAHs over the entire study area in Tokyo. At this study scale especially at the roadside, however, a high pPAHs concentration observed in Tokyo and in Bangkok was predominantly located at low wind speed, <1.0 and 0.4 m s -1, respectively, and along

  7. Development of particle induced gamma-ray emission methods for nondestructive determination of isotopic composition of boron and its total concentration in natural and enriched samples.

    Science.gov (United States)

    Chhillar, Sumit; Acharya, Raghunath; Sodaye, Suparna; Pujari, Pradeep K

    2014-11-18

    We report simple particle induced gamma-ray emission (PIGE) methods using a 4 MeV proton beam for simultaneous and nondestructive determination of the isotopic composition of boron ((10)B/(11)B atom ratio) and total boron concentrations in various solid samples with natural isotopic composition and enriched with (10)B. It involves measurement of prompt gamma-rays at 429, 718, and 2125 keV from (10)B(p,αγ)(7)Be, (10)B(p, p'γ)(10)B, and (11)B(p, p'γ)(11)B reactions, respectively. The isotopic composition of boron in natural and enriched samples was determined by comparing peak area ratios corresponding to (10)B and (11)B of samples to natural boric acid standard. An in situ current normalized PIGE method, using F or Al, was standardized for total B concentration determination. The methods were validated by analyzing stoichiometric boron compounds and applied to samples such as boron carbide, boric acid, carborane, and borosilicate glass. Isotopic compositions of boron in the range of 0.247-2.0 corresponding to (10)B in the range of 19.8-67.0 atom % and total B concentrations in the range of 5-78 wt % were determined. It has been demonstrated that PIGE offers a simple and alternate method for total boron as well as isotopic composition determination in boron based solid samples, including neutron absorbers that are important in nuclear technology.

  8. Surface Tension Estimates for Droplet Formation in Slurries with Low Concentrations of Hydrophobic Particles, Polymer Flocculants or Surface-Active Contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Gauglitz, Phillip A.; Mahoney, Lenna A.; Blanchard, Jeremy; Bamberger, Judith A.

    2011-06-10

    In support of the K-Basin project, Pacific Northwest National Laboratory (PNNL) was requested to evaluate the appropriate surface tension value to use in models predicting the formation of droplets from spray leaks of K-Basin slurries. The specific issue was whether it was more appropriate to use the surface tension of pure water in model predictions for all plausible spray leaks or to use a lower value. The surface tension of K-Basin slurries is potentially affected not only by particles but by low concentrations of nonionic polyacrylamide flocculant and perhaps by contaminants with surfactant properties, which could decrease the surface tension below that of water. A lower surface tension value typically results in smaller droplets being formed with a larger fraction of droplets in the respirable size range, so using the higher surface tension value of pure water is not conservative and thus needs a strong technical basis.

  9. The relationship between cloud condensation nuclei (CCN concentration and light extinction of dried particles: indications of underlying aerosol processes and implications for satellite-based CCN estimates

    Directory of Open Access Journals (Sweden)

    Y. Shinozuka

    2015-01-01

    Full Text Available We examine the relationship between the number concentration of boundary-layer cloud condensation nuclei (CCN and light extinction to investigate underlying aerosol processes and satellite-based CCN estimates. Regression applied to a variety of airborne and ground-based measurements identifies the CCN (cm−3 at 0.4 ± 0.1% supersaturation with 100.3α +1.3 σ0.75 where σ (M m−1 is the 500 nm extinction coefficient by dried particles and α is the Angstrom exponent. The deviation of one kilometer horizontal average data from this approximation is typically within a factor of 2.0. ∂ log CCN/∂ log σ is less than unity because, among other explanations, aerosol growth processes generally make particles scatter more light without increasing their number. This, barring extensive data aggregation and special meteorology-aerosol connections, associates doubling of aerosol optical depth with less than doubling of CCN, contrary to common assumptions in satellite-based analysis of aerosol-cloud interactions.

  10. Physicochemical variations in atmospheric aerosols recorded at sea onboard the Atlantic-Mediterranean 2008 Scholar Ship cruise (Part I): Particle mass concentrations, size ratios, and main chemical components

    Science.gov (United States)

    Pérez, Noemí; Moreno, Teresa; Querol, Xavier; Alastuey, Andrés; Bhatia, Ravinder; Spiro, Baruch; Hanvey, Melanie

    2010-07-01

    We report on ambient atmospheric aerosols present at sea during the Atlantic-Mediterranean voyage of Oceanic II (The Scholar Ship) in spring 2008. A record was obtained of hourly PM 10, PM 2.5, and PM 1 particle size fraction concentrations and 24-h filter samples for chemical analysis which allowed for comparison between levels of crustal particles, sea spray, total carbon, and secondary inorganic aerosols. On-board monitoring was continuous from the equatorial Atlantic to the Straits of Gibraltar, across the Mediterranean to Istanbul, and back via Lisbon to the English Channel. Initially clean air in the open Atlantic registered PM 10 levels polluted by increasingly coarse PM as the ship approached land. Away from major port cities, the main sources of atmospheric contamination identified were dust intrusions from North Africa (NAF), smoke plumes from biomass burning in sub-Saharan Africa and Russia, industrial sulphate clouds and other regional pollution sources transported from Europe, sea spray during rough seas, and plumes emanating from islands. Under dry NAF intrusions PM 10 daily mean levels averaged 40-60 μg m -3 (30-40 μg m -3 PM 2.5; c. 20 μg m -3 PM 1), peaking briefly to >120 μg m -3 (hourly mean) when the ship passed through curtains of higher dust concentrations amassed at the frontal edge of the dust cloud. PM 1/PM 10 ratios ranged from very low during desert dust intrusions (0.3-0.4) to very high during anthropogenic pollution plume events (0.8-1).

  11. Surgical smoke and ultrafine particles

    Directory of Open Access Journals (Sweden)

    Nowak Dennis

    2008-12-01

    Full Text Available Abstract Background Electrocautery, laser tissue ablation, and ultrasonic scalpel tissue dissection all generate a 'surgical smoke' containing ultrafine ( Methods To measure the amount of generated particulates in 'surgical smoke' during different surgical procedures and to quantify the particle number concentration for operation room personnel a condensation particle counter (CPC, model 3007, TSI Inc. was applied. Results Electro-cauterization and argon plasma tissue coagulation induced the production of very high number concentration (> 100000 cm-3 of particles in the diameter range of 10 nm to 1 μm. The peak concentration was confined to the immediate local surrounding of the production side. In the presence of a very efficient air conditioning system the increment and decrement of ultrafine particle occurrence was a matter of seconds, with accumulation of lower particle number concentrations in the operation room for only a few minutes. Conclusion Our investigation showed a short term very high exposure to ultrafine particles for surgeons and close assisting operating personnel – alternating with longer periods of low exposure.

  12. Pretreating lignocellulosic biomass by the concentrated phosphoric acid plus hydrogen peroxide (PHP) for enzymatic hydrolysis: evaluating the pretreatment flexibility on feedstocks and particle sizes.

    Science.gov (United States)

    Wang, Qing; Wang, Zhanghong; Shen, Fei; Hu, Jinguang; Sun, Fubao; Lin, Lili; Yang, Gang; Zhang, Yanzong; Deng, Shihuai

    2014-08-01

    In order to seek a high-efficient pretreatment path for converting lignocellulosic feedstocks to fermentable sugars by enzymatic hydrolysis, the concentrated H₃PO₄ plus H₂O₂ (PHP) was attempted to pretreat different lignocellulosic biomass for evaluating the pretreatment flexibility on feedstocks. Meanwhile, the responses of pretreatment to particle sizes were also evaluated. When the PHP-pretreatment was employed (final H₂O₂ and H₃PO₄ concentration of 1.77% and 80.0%), 71-96% lignin and more than 95% hemicellulose in various feedstocks (agricultural residues, hardwood, softwood, bamboo, and their mixture, and garden wastes mixture) can be removed. Consequently, more than 90% glucose conversion was uniformly achieved indicating PHP greatly improved the pretreatment flexibility to different feedstocks. Moreover, when wheat straw and oak chips were PHP-pretreated with different sizes, the average glucose conversion reached 94.9% and 100% with lower coefficient of variation (7.9% and 0.0%), which implied PHP-pretreatment can significantly weaken the negative effects of feedstock sizes on subsequent conversion.

  13. THE CORRELATION BETWEEN INDOOR RADON CONCENTRATIONS AND GEOLOGICAL BACKGROUNDS IN SOME TYPICAL AREAS OF BEIJING AND GUANGDONG%北京广东典型地区室内氡气浓度与地质背景关系

    Institute of Scientific and Technical Information of China (English)

    秦春艳; 王南萍; 肖磊; 储星铭

    2012-01-01

    For the purpose of studying the indoor radon level under different geological backgrounds, the authors measured indoor radon concentrations by pulse chamber radon monitor AlphaGUARD in some typical areas of Guangdong and Beijing, and also made long-term monitoring of indoor radon concentrations at a measuring site in Guangdong. The results show that surface lithology is one of the most important factors affecting indoor radon. The indoor radon in the granite area is higher than that in other lilhologic areas, and the level of indoor radon in Guangdong is apparently higher than that in Beijing. The average concentrations of indoor radon in Guangdong and Beijing are respectively 69.98 Bq/m3 and 43.97 Bq/m3 for granite area, and 43.60 Bq/m3,35.74 Bq/m3 for Quaternary area. The level of indoor radon in the residence is slightly higher than that in office buildings and restaurants. The study of the distribution and level of indoor radon in combination with geological background is of guiding significance for the selection of the indoor radon survey points and also has important practical value for regional scale indoor radon evaluation.%为了解不同地质背景条件室内氡浓度水平,采用脉冲电离室测氡仪AlphaGUARD测量了北京广东不同地质背景典型测点的室内氡浓度,同时对广东某一测点进行了长期的室内氡监测.测量和研究结果表明:地表岩性是影响室内氡浓度高低的重要因素之一.地处花岗岩地区的建筑物内氡浓度高于其他岩性地区的室内氡浓度,广东室内氡水平明显高于北京地区,广东北京花岗岩地区的平均室内氡浓度分别为69.98 Bq/m3和43.97 Bq/m3,第四系覆盖地区的平均室内氡浓度分别为43.60 Bq/m3和35.74 Bq/m3.民用住宅卧室内的室内氡浓度略高于公共建筑物办公室内的室内氡浓度.因此,结合地质背景研究室内氡的水平与分布对指导开展室内氡调查中确定抽样方案、选择测点及

  14. Concentrations and particle size effect of heavy metals in the street dust of Xuchang City%许昌市街道灰尘重金属含量及其粒径效应

    Institute of Scientific and Technical Information of China (English)

    闫慧; 肖军; 张俊丽

    2016-01-01

    Background aim and scope Street dust is an important pathway for pollution material in the urban environment. Street dust often becomes a sink for both industrial and residential pollutants, including waste incineration residues, vehicle exhaust emissions, and products of tire wear, metallic fragments, fossil fuel combustion emissions and garden soil. Among the pollutants in street dust, heavy metals are often more severe than others. Heavy metal elements are often not decomposed by microorganisms and may become enriched through the food chain, affecting human health, especially that of children and elderly people. Moreover, heavy metals have more affinity to establish metallic bonds with ferrous material, which leads to enhancement of the magnetic susceptibility of street dust. Many studies have reported excellent relationships between magnetic susceptibility and the levels of some heavy metals in street dust or industrial/urban soils, this relationship forms the basis for the use of magnetic methods in pollution studies. Therefore, magnetic susceptibility characteristics of street dust can be used to relfect a city’s heavy metal pollution. Furthermore, heavy metal enrichment regularity in street dust research has important signiifcance. Along with the remarkably fast development of the economy and urbanization of China, environmental pollution is becoming a more serious problem in many cities. Xuchang City is one core city of the Central Megalopolis of China;industrial pollution and vehicle exhaust emissions have aggravated the city’s pollution in recent years, especially the particulate matter pollution. At present particle size effect of heavy metal of Xuchang City street dust has not been reported. This present research studied the Xuchang City street dust particle size and heavy metals concentration. Our main aims are to analyze the particle size and heavy metal concentration and to identify the relationships between them. The results may provide useful

  15. The effects of the built environment, traffic patterns, and micrometeorology on street level ultrafine particle concentrations at a block scale: Results from multiple urban sites.

    Science.gov (United States)

    Choi, Wonsik; Ranasinghe, Dilhara; Bunavage, Karen; DeShazo, J R; Wu, Lisa; Seguel, Rodrigo; Winer, Arthur M; Paulson, Suzanne E

    2016-05-15

    This study attempts to explain explicitly the direct and quantitative effects of complicated urban built-environment on near-road dispersion and levels of vehicular emissions at the scale of several city blocks, based on ultrafine particle concentrations ([UFP]). On short timescales, ultrafine particles are an excellent proxy for other roadway emissions. Five measurement sites in the greater Los Angeles with different built environments but similar mesoscale meteorology were explored. After controlling for traffic, for most sampling days and sites, morning [UFP] were higher than those in the afternoon due to limited dispersion capacity combined with a relatively stable surface layer. [UFP] at the intersection corners were also higher than those over the sampling sites, implying that accelerating vehicles around the intersections contributed to [UFP] elevation. In the calm morning, the areal aspect ratio (Ararea), developed in this study for real urban configurations, showed a strong relationship with block-scale [UFP]. Ararea includes the building area-weighted building height, the amount of open space, and the building footprint. In the afternoon, however, when wind speeds were generally higher and turbulence was stronger, vertical turbulence intensity σw was the most effective factor controlling [UFP]. The surrounding built environment appears to play an indirect role in observed [UFP], by affecting surface level micrometeorology. The effects are substantial; controlling for traffic, differences in Ararea and building heterogeneity were related to differences in [UFP] of factors of two to three among our five study sites. These results have significant implications for pedestrian exposure as well as transit-oriented urban planning. PMID:26938315

  16. Comparison of fluvial suspended-sediment concentrations and particle-size distributions measured with in-stream laser diffraction and in physical samples

    Science.gov (United States)

    Czuba, Jonathan A.; Straub, Timothy D.; Curran, Christopher A.; Landers, Mark N.; Domanski, Marian M.

    2014-01-01

    Laser-diffraction technology, recently adapted for in-stream measurement of fluvial suspended-sediment concentrations (SSCs) and particle-size distributions (PSDs), was tested with a streamlined (SL), isokinetic version of the Laser In-Situ Scattering and Transmissometry (LISST) for measuring volumetric SSCs and PSDs ranging from 1.8-415 µm in 32 log-spaced size classes. Measured SSCs and PSDs from the LISST-SL were compared to a suite of 22 datasets (262 samples in all) of concurrent suspended-sediment and streamflow measurements using a physical sampler and acoustic Doppler current profiler collected during 2010-12 at 16 U.S. Geological Survey streamflow-gaging stations in Illinois and Washington (basin areas: 38 – 69,264 km2). An unrealistically low computed effective density (mass SSC / volumetric SSC) of 1.24 g/ml (95% confidence interval: 1.05-1.45 g/ml) provided the best-fit value (R2 = 0.95; RMSE = 143 mg/L) for converting volumetric SSC to mass SSC for over 2 orders of magnitude of SSC (12-2,170 mg/L; covering a substantial range of SSC that can be measured by the LISST-SL) despite being substantially lower than the sediment particle density of 2.67 g/ml (range: 2.56-2.87 g/ml, 23 samples). The PSDs measured by the LISST-SL were in good agreement with those derived from physical samples over the LISST-SL's measureable size range. Technical and operational limitations of the LISST-SL are provided to facilitate the collection of more accurate data in the future. Additionally, the spatial and temporal variability of SSC and PSD measured by the LISST-SL is briefly described to motivate its potential for advancing our understanding of suspended-sediment transport by rivers.

  17. Influence of mineral dust and sea spray supermicron particle concentrations and acidity on inorganic NO3− aerosol during the 2013 Southern Oxidant and Aerosol Study

    Directory of Open Access Journals (Sweden)

    H. M. Allen

    2015-05-01

    Full Text Available The inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high aerosol mass loading during the summer, as part of the 1 June to 15 July 2013 Southern Oxidant and Aerosol Study (SOAS campaign. Measurements using a Monitor for AeRosols and GAses (MARGA, an ion chromatograph coupled with a wet rotating denuder and a steam-jet aerosol collector for monitoring of ambient inorganic gas and aerosol species, revealed two periods of high aerosol nitrate (NO3− concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of coarse mode mineral or sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 μm diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3 and particles, reactions that are facilitated by transport of mineral dust and sea spray aerosol from a source within the United States. The observed high aerosol acidity prevents the formation of NH4NO3, the inorganic nitrogen species often dominant in fine-mode aerosol at higher pH. Calculation of the rate of the heterogeneous uptake of HNO3 on mineral aerosol supports the conclusion that aerosol NO3− is produced primarily by this process, and is likely limited by the availability of mineral dust surface area. Modeling of NO3− and HNO3 by thermodynamic equilibrium models (ISORROPIA II and E-AIM reveals the importance of including mineral cations in the southeastern United States to accurately balance ion species and predict gas/aerosol phase partitioning.

  18. Closure between ice-nucleating particle and ice crystal number concentrations in ice clouds embedded in Saharan dust: Lidar observation during the BACCHUS Cyprus 2015 campaign

    Science.gov (United States)

    Mamouri, Rodanthi-Elisavet; Ansmann, Albert; Bühl, Johannes; Engelmann, Ronny; Baars, Holger; Nisantzi, Argyro; Hadjimitsis, Diofantos; Atkinson, James; Kanji, Zamin; Vrekoussis, Michalis; Sciare, Jean; Mihalopoulos, Nikos

    2016-04-01

    For the first time, we compare ice-nucleating particle number concentration (INPC) derived from polarization lidar (Mamouri and Ansmann, 2015) with ice crystal number concentrations (ICNC) in ice cloud layers embedded in the observed Saharan dust layers (at heights above 6 km and corresponding temperatures from -20 to -40°C). ICNC is estimated from the respective cirrus extinction profiles obtained with the same polarization lidar in combination with Doppler lidar measurements of the ice crystal sedimentation speed from which the mean size of the crystals can be estimated. Good agreement between INPC and ICNC was obtained for two case studies of the BACCHUS Cyprus 2015 field campaign with focus on INPC profiling. The campaign was organized by the Cyprus Institute, Nicosia, where a lidar was deployed. Additionaly, observations of AERONET and EALINET Lidar stations during the BACCHUS Cyprus 2015 field campaign, performed by Cyprus University of Technology in Limassol. Both, INPC and ICNC were found in the range from 10-50 1/L. Lidar-derived INPC values were also compared with in-situ INPC measurements (Horizontal Ice Nucleation Chamber, HINC, ETH Zurich, deployed at Agia Marina, at 500 m a.s.l., 30 km west of the lidar site). Reasonable and partly good agreement (during dust events) was found between the two retrievals. The findings of these closure studies corroborate the applicability of available INPC parameterization schemes (DeMott et al., 2010, 2015) implemented in the lidar retrieval scheme, and more generally INPC profiling by using active remote sensing (at ground and in space with CALIPSO and EarthCARE lidars).

  19. Effects of subchronic exposures to concentrated ambient particles in mice. IX. Integral assessment and human health implications of subchronic exposures of mice to CAPs.

    Science.gov (United States)

    Lippmann,